Return this book on or before the Latest Date stamped below. University of Illinois Library \- Digitized by the Internet Archive in 2017 with funding from University of Illinois Urbana-Champaign Alternates https://archive.org/details/chemistrygeneral00attf_0 CHEMISTRY GENERAL, MEDICAL, AND PHARMACEUTICAL, INCLUDING THE CHEMISTRY OF THE U. S. PHARMACOPffilA. A MANUAL ON THE GENERAL PRINCIPLES OF THE SCIENCE, AND THEIR APPLICATIONS TO MEDICINE AND PHARMACY. BY JOHN ATTFIELD, PhD., F.O.S., PROFESSOR OF PRACTICAL CHEMISTRY TO THE PHARMACEUTICAL SOCIETY OF FORMERLY DEMONSTRATOR OF CHEMISTRY AT ST. BARTHOLOMEW’S HOSPITAL, LONDON; . HONORARY MEMBER OF THE AMERICAN PHARMACEUTICAL ASSOCIATION; HONORARY MEMBER OF THE COLLEGES OF PHARMACY OF PHILADELPHIA, NEW YORK, MASSACHUSETTS, AND CHICAGO ; HONORARY CORRESPONDING MEMBER OF THE SOCIETY OF PHARMACY OF PARIS ; SECRETARY OF THE BRITISH PHARMACEUTICAL CONFERENCE. FIFTH EDITION. REVISED FROM THE FOURTH (ENGLISH) EDITION BY THE AUTHOR. PHILADELPHIA: HENRY C . LEA. 18Y3. “Bat the greatest error of all is, mistaking the ultimate end of knowledge ; for some men covet knowledge out of a natural curiosity and inquisitive temper; some to entertain the mind with variety and delight ; some for ornament and reputation ; some for victory and contention ; many for lucre and a livelihood ; and but few for employing the Divine gift of reason to the use and benefit of mankind. Thus some appear to seek in knowledge a couch for a searching spirit ; others, a walk for a wandering mind ; others, a tower of state; others, a fort, or commanding ground; and others, a shop for profit or sale, instead of a storehouse for the glory of the Creator and the endowment of human life.” — Lord Bacon. Entered according to the Act of Congress, in the year 1S73, by HENRY C. LEA, in the Ofiice of the Librarian of Congress. All rights reserved. o c a £ c ar. or 03 O o> r" 0 PREFACE. The short title on the back of a book, and even the words on the title-page, are generally, and even necessarily, im- perfect descriptions of the contents, and hence not unfre- quently induce at the outset misconceptions in the minds of readers. The Author of “Chemistiy, General, Medical, and Pharmaceutical” would at once state, therefore, that his sole aim is to teach the general truths of chemistry to medical and pharmaceutical pupils. Only in a conventional sense would he speak of such subjects as Medical and Phar- maceutical Chemistry; for the truths of Chemistry are the same for all students — crystalline verities which cannot be expanded or compressed to suit any class of workers. The leading principles of the science, however, can be as easily illustrated by or deduced from those facts which have in- terest as from those which have little or no special interest to the class addressed ; and such a course is adopted in this volume. This manual is intended, then, as a systematic exponent of the general truths of Chemistry, but is written solely for the pupils, assistants, and principals engaged in medi- cine and pharmacy. It will be found equally useful as a reading-book for gentlemen having no opportunities of attending lectures or performing experiments, and as a handbook for college pupils ; while its comprehensive Index, containing six thousand references, will fit the work for after-consultation in the course of business or professional practice. From other chemical text-books it differs in three par- ticulars : first, in the exclusion of matter relating to com- pounds which at present are only of interest to the scien- tific chemist ; secondly, in containing more or less of the chemistry of every substance recognized officially, or in 281952 IV PREFACE. general practice, as a remedial agent; thirdly, in the para- graphs being so cast that the volume may be used as a guide in studying the science experimentally. The order of subjects is that which, in the author’s opinion, best meets the requirements of medical and phar- maceutical students in Great Britain and America. Intro- ductory pages are devoted to a few leading properties of the elements. A review of the facts thus unfolded affords opportunity for stating the views of philosophers respect- ing the manner in which these elements influence each other. The consideration in detail of the relations of the elementary and compound radicals follows, synthetical and analytical bearings being pointed out, and attention frequently directed to connecting or underlying truths or general principles. The chemistry of substances naturally associated in vegetables and animals is next considered. Practical toxicolog}^ and the chemical as well as microsco- pical characters of morbid urine, urinary sediments, and calculi are then given. The concluding sections form a laboratory-guide to the chemical and physical study of quantitative analysis. In the appendix is a long table of tests for impurities in medicinal preparations — also a short one of the saturating-powers of acids and alkalies, designed for use in prescribing and dispensing. In the course of the treatment outlined in the preceding paragraph, it will be observed that the whole of the ele- ments are first noticed superficially and then fully, and that the chemistry of the common metallic radicals precedes that of the rarer; while the sections on the acidulous radi- cals are similarly divided. The basylous radicals will be found to be arranged according to analytical relations, the common acidulous according to exchangeable value or quantivalence, and the rarer acidulous radicals alphabeti- cally. It will be apparent, also, that in certain cases the same classes of facts and principles are brought three or four times under consideration, the points of view, however, differing according as interest is concentrated on physical, synthetical, analytical, or quantitative properties. This PREFACE. V arrangement of matter was adopted partly from the belief that the separate and general truths of chemistry never enter the mind in the order of any scientific classification at pre- sent possible. In the current state of chemical knowledge, consistency in the methodical arrangement even of elements can only be carried out in one direction, and is necessarily accompanied by inconsistencies in other directions, a result most perplexing to learners, and hence totally subversive of the chief advantage of classification. For this reason the writer has preferred to lead up to, rather than follow, sci- entific classification — has -allowed analogies and affinities to suggest, rather than be suggested by, classification. Among the acidulous radicals, especially, any known sys- tem of classification would have given undue prominence to one set of relations and undeserved obscurity to others. Then, by separating more important from less important matter, instruction is adapted to the wants of gentlemen whose opportunities of studying chemistry vary greatly, and are unavoidably insufficient to enable them to gain a thorough knowledge of the science. One great advantage of the mode of treatment is that diffu^lties of nomen- clature, notation, chemical constitution, and even those arising from conventionality of language, are explained as they arise, instead of being massed under the head of “Introductory Chapters,’^ “Preliminary Considerations,” or “ General Remarks,” which are commonly too difficult to be understood by a beginner, too voluminous to be re- membered except by the aid of subsequent lessons, and are consequently the cause of much trouble and confusion. This plan has also admitted of greater prominence being- given to “ The General Principles of Chemical Philosophy,” the only section which the student is asked frequently to return to and employ in the interpretation of the pheno- mena obtained by experiment. An elementary knowledge of the subjects of Gravitation, Heat, Light, Sound, Elec- tricity, and Magnetism cannot be too strongly recom- mended to the student of Chemistiy. The first portion I* VI PREFACE. of this Manual would have been devoted to an exposition of these branches of Physics, so far as they bear on Che- mistry, did not the many special books on Physics render such a course unnecessary. Quantitative chemical analysis frequently involving determinations of temperature, specific gravity, and atmospheric pressure, a few paragraphs on these subjects are made introductory to the sections on quantitative operations. Dalton’s hypothesis of the atomic condition of all matter is adopted in this book, the author believing that, in the present state of knowledge and education, philosophic conceptions regarding chemistry can only be taught to medical, pharmaceutical, and the great majority of general students in some such objective manner. The chemical notation of the work is in accordance with modern theories. Equations illustrative of pharmacopceial processes have a name attached to each formula. Chemical nomenclature has been modernized to the ex- tent of defining the alkali-metal and earthy salts as those of potassium, sodium, ammonium, barium, calcium, magne- sium, and aluminium, instead of potash, soda, ammonia, baryta, lime, magnesia, and alumina. The author con- fidently believes that this change, founded on views now adopted by all prominent writers on chemistry, and used in the Pharmacopoeia of the United States, will be accepted and become popular with pharmacists ; it is a step in the direction of simplicity and consistenc}^, and involves far less hypothesis than is contained in the old system. The name nitrate of potash, for example, was based on the pure assumption that nitre contained oxide of potassium or potash and nitric anhydride, then erroneously termed acid. By the modern name nitrate of potassium, all that is in- tended to be conveyed is that nitre contains the element common to all potassium compounds, and the group of elements common to all nitrates. Under the old method, students always experienced difficulty in distinguishing salts of the metal from salts of its oxide — salts of potas- sium, for instance, from salts of potash; under tlie nevy PREFACE. vii view no such difficulty arises. Names such as potassium nitrate or potassic nitrate are also consistent with modern views, but for general adoption are too unlike the original. The contractions in Latin for names like “ nitrate of potas- sium’^ are identical with those names resembling “ nitrate of potash;” an accidental circumstance that will much facilitate the general introduction of the former among medical practitioners and pharmacists, and a practical ad- vantage that must determine the choice over the other chemically equivalent names just mentioned. The author ventures to express his extreme gratification at the adop- tion of this system of nomenclature in the recently pub- lished Pharmacopoeia of the United States (1873). The Metric System of Weights and Measures (that which, doubtless, is destined to supersede all others) is alone used in the sections on Quantitative Analysis. In other parts of the Manual avoirdupois weights and impe- rial measures are employed. It is hoped that the numerous etymological references scattered throughout the following pages will be found useful. Words in Greek have been rendered in English characters, letter for letter. The word “ official” is used throughout for things recognized officially by the compilers of the Pharmacopoeia ; officinal” in its original applica- tion to the officina or shop. Students are strongly recommended to test their pro- gress by frequent examination. To this end appropriate questions are appended to each subject. The Author’s ideal of a Manual of Chemistry for medi- cal and pharmaceutical students (one he is conscious of not having yet realized) is one in which the chemistry of every substance having interest for the followers of medi- cine and pharmacy is noticed at more or less length in proportion to its importance, and at least its position in relation to the leading principles of chemistry set forth with all attainable exactness. Such a work will doubtless in certain parts partake of the character of a dictionary ; but this is by no means a fault, especially if a good index viii PREFACE. be appended ; for the points of contact between pure and applied chemistry are thus multiplied, and abundant out- lets supplied, by which a lover of the science may pass into other chemical domains by aid of other guides, or even into the regions of original research. Among the rarer alkaloids, bitter bodies, glucosides, salts of organic radi- cals, solid fats, fixed oils, volatile oils, resins, oleo-resins, gum-resins, balsams, and coloring-matters, mentioned in this volume, will be found many such points whence the ardent student may start for the well-known obscure or untrodden paths of scientifiie chemistry. Within five years a demand has arisen for five editions of this Manual. The First was intended as a handbook of practical chemistry for medical and pharmaceutical pupils ; but the notes and remarks made respecting most of the ex- periments were found to be so useful by students that this portion of the volume was in the Second Edition suffi- ciently extended to render the book more fairly complete in itself. In response to a call from professional friends in the United States in 1870, the work was revised by the Author for the followers of medicine and pharmacy in America, the chemistry of the Preparations and Materia Medica of the United States Pharmacopoeia being intro- duced, and such other adaptations included as to form a Third Edition. A Fourth was presented to English work- ers in the autumn of 1872, and on that is now founded this Fifth Edition for American students. Each of the latter editions is entirely distinct from the other ; but both con- tain such corrections and additions (altogether about seventj^ P^-ges) as seemed necessary to present the science in its latest developments — also a rewritten chapter on the General Principles of Chemical Philosophy, and black- letter headings to all paragraphs relating to Preparations of the respective Pharmacopoeias. 17 Bloomsbury Square, London, Mar ell, 1873. APPARATUS. IX APPARATUS FOR EXPERIMENTS IN ANALYSIS. List of Apparatus suitable for a three months’ course of practical chemistry in the summer session of medical schools, or for any similar series of lessons — including the preparation of elementary gases, ana- lytical reactions of common metals and acidulous radicals, analysis of single salts, chemical toxicology, and the examination of urine, urinary sediments, and calculi : — One dozen test-tubes. Test-tube stand. Test-tube cleaning-brush. A few pieces of glass tubing, 8 to 16 in. long, with a few inches of India-rubber tubing to fit. Small flask. Two small beakers. Two small funnels. Two watch-glasses. Two or three glass rods. Wash-bottle. Small pestle and mortar. A 2-pint earthenware basin. ( This set, packed in a deal-box, apparatus maker for about seven A 2-inch and a 3-inch evap. basin. Two porcelain crucibles. Blowpipe. Crucible tongs. Bound file. Triangular file. Small retort-stand. Sand-tray. Wire triangles. Platinum wire and foil. Test-paper. Filter-paper. Towel. Two dozen corks. can be obtained of any chemical- dollars.) APPARATUS FOR EXPERIMENTS IN SYNTHESIS AND ANALYSIS. A larger set, suitable for the performance of most of the synthe- tical as well as analytical experiments described in this manual : — A set of evaporating-basins, of the following sizes : — One 8J-inch. One 4-inch. One l^-inch. Two 3-inch. One 6J-inch. One retort-stand and three rings. Two test-glasses. One half-pint fiask. One half-quire filter-paper. Two porcelain crucibles. One measure-glass, 5 oz. Blowpipe, 8-inch, Black’s. Two glass funnels. One doz. test-tubes (German glass). One test-tube brush. One pair of 8-inch brass crucible- tongs. Two soup-plates. One fiat-plate. Two spatula knives. One pair of scissors. One round file. One triangular file. One half-pound glass rod. One half-pound glass tubing. One ft. small India-rubber tubing. Three dozen corks of various sizes. Platinum wire and foil. Test-papers. A nest of three beakers. [This set, packed in a case, can be obtained of any chemical- apparatus maker for about twelve dollars.) A sponge, towels, and note-book may be included. X APPARATUS AND REAGENTS. FURNITURE OF A LABORATORY. The following apparatus should be ready to the hand of students following an extended course of practical chemistry, in a room set apart for the purpose : — A bench or table and stool. Water-supply and waste-pipe. A cupboard attached to a chim- ney with an outward draught. A furnace fed with coke ; tongs, hot-plate, or sand-bath, etc. A waste-box. Shelves for chemicals and other materials in jars or bottles. Gas-supply and lamp with flexible tube (or a spirit lamp and spirit). Test-tube rack, two dozen holes. Iron stand or cylinder for sup- porting large dishes. Iron adaptors for fitting dishes to cylinder. Pestle and mortar, 5 or 6 inches. One 6-inch funnel. Brown pan, 1 or 2-gallon. White jug, 1-gallon. Water-bottle, quart. Twenty-eight test-bottles, 6-oz. Other articles, such as flasks, retorts, receivers, condensers, large evaporating-dishes, may be obtained as wanted. In Quantitative Analysis the apparatus described in the sections on that subject will be required. REAGENTS. Certain chemicals are used so frequently in analytical processes that it is desirable to have small quantities placed in bottles in front of the operator. As these reagents or “tests’" are generally em- ployed in a state of solution, nearly all the solid salts may at once iDe dissolved (in distilled water). The bottles employed should be well stoppered, and of 5 or 6 ounces capacity. The bottles should not be more than three-quarters full ; single drops, if required, can then be poured out with ease and precision. The following list of test solutions is recommended; directions for methods of preparing those not readily purchasable will be found by referring to the Index : — Sulphuric Acid, strong. Nitric. Acid, strong. Hydrochloric Acid, strong. Acetic Acid, strong. Sol. of Potash, 5 per cent, or B.P. “ Soda, 5 to 15 per cent. “ Ammon. 10 per cent, or B.P. Lime-water, saturated. The next nine may contain about 10 per cent, of solid salt : — Carbonate of Ammonium, with a little solution of Ammonia added. Chloride of Ammonium. Phosphate or Arseniate of Am- monium. Sulphydrate of Ammonium. Chloride of Barium. Chloride of Calcium. Phosphate of Sodium. Neutral Chromate. CHEMICALS. XI The succeeding seven may have a strength of about 5 per cent. : — Ferrocyanide of Patassium. Ferridcyanide of Potassium. Iodide of Potassium. Oxalate of Ammonium. Perchloride of Iron. Nitrate of Silver. Perchloride of Platinum. LISTS OF CHEMICALS. List of chemicals necessary for the practical study of the non- metallic elements mentioned on pp. 13 to 28. The quantities are sufficient for several experiments. Chlorate of Potassium . . I oz. Black Oxide of Manganese 1 oz. Zinc 1 oz. Oil of Yitriol 2 oz. Phosphorus . . Hydrochloric Acid Sulphur .... Iodine .... 2 oz. 1 oz. i oz. i oz. List of chemicals necessary for the analytical study of the metal- lic and acidulous radicals (pages 51 to 310). The quantities will depend on the frequency with which experiments are repeated or analysis performed ; those mentioned are sufficient for one or two students. The articles are given in the order in which they will be required. The eight substances mentioned in the above list are included. The set of test solutions Bicarbonate of Potassium 1 oz. described on the pre- Acetate of Lead .... 1 oz. vious page. Cyanide of Potassium . . i oz. Carbonate of Potassium 1 OZ. Hyposulphite of Sodium 1 oz. Tartaric Acid 1 oz. A Lithium salt ... 10 grs. Litmus 1 4 oz. Nitrate of Strontium . . i oz. Sulphate of Magnesium . . 1 oz. Black Oxide of Manganese i\h. Sulphate of Zinc .... 1 oz. Chloride of Manganese . . i oz. Alum • . 1 oz. Chloride of Cobalt . . 50 grs. Sulphide of Iron .... 1 lb. Nitrate of Nickel . . . i oz. Oak-galls 1 oz. Chloride of Chromium . . i oz. Sulphocyanate of Potassium 1 4 oz. Gold leaves 2 or 3. White Arsenic .... i oz. Chloride of Cadmium . . i oz. Zinc 1 2 lb. Nitrate of Bismuth . . . i oz. Charcoal . . . . . . 1 lb. Bromide of Potassium . . i oz. Sulphate of Iron . . i . 1 oz. Starch 1 oz. Copper Foil 1 oz. Nitrate of Potassium . . 1 oz. Sulphate of Copper . . . 1 oz. Copper borings or turnings l.oz. Tartar Emetic .... 1 2 oz. Indigo i oz. Mercury 1 oz. Chlorate of Potassium . . 1 oz. Corrosive Sublimate . . . i oz. Iodine i oz. Calomel ....... X oz. Spirit of Wine .... 1 oz. Tin 1 oz. Sulphur 1 oz. xii CHEMICALS. Acid Oxalate of Potassium 1 oz. Citric Acid 1 oz. Phosphorus 1 oz. Borax 1 oz. Turmeric 1 oz. Benzoic Acid . Pluor Spar . . Tannic Acid Gallic Acid Pyrogallic Acid . . 50 grs. . . . 1 oz. . . 50 grs. . . 50 grs. . . 50 grs. The quantities of materials required for the study of chemistry synthetically will necessarily vary with the desires and tastes of the operator, or according to the number and requirements of stu- dents working together. CONTENTS. PAGE Preface iii Apparatus . . . ix Reagents x Lists of Chemicals • . . . xi Introduction 13 General Properties of the ^s' on-Metallic Elements 1 5 Symbols and Derivation of Names qf Elements . 28 The General Principles of Chemical Philosophy . 32 Common Metallic Elements, their Official Pre- parations, AND Tests : — Salts of Potassium, Sodium, Ammonium, Barium, Calcium, Magnesium, Zinc, Aluminium, Iron, Arsenicum, Antimony, Copper, Mercury, Lead, Silver 52 Analytical Charts, for Ordinary Metals . . . 197 Rarer Metallic Elements, their Official Prepara- tions, AND Tests : — Salts of Lithium, Strontium, Manganese, Cobalt, Nickel, Chromium, Tin, Gold, Platinum, Cad- mium, Bismuth . 200 Analytical Charts, for all Metals 229 Common Acidulous Radicals, Official Acids, and Tests : — Chlorides, Bromides, Iodides, Cyanides, Nitrates, Chlorates, Acetates, Sulphides, Sulphites, Sulphates, Carbonates, Oxalates, Tartrates, Citrates, Phosphates, Borates 2 235 XIV CONTENTS. PAGE Salts of Rarer Acidulous Radicals : — Benzoates, Cyanates, Formates, Hippurates, Fer- ROCYANIDES, FeRRIDCYANIDES, FlUORIDES, HyPO- PHOSPHITES, Hyposulphites, Lactates, Malates, Meconates, Metaphosphates, [N'itrites, Phos- phites, Pyrophosphates, Silicates, Sulphocy- anates, T annates, Gallates, Urates, Yaleri- ANATES 298 Analytical Chart for Acidulous Radicals . . . 326 Sy^stematic Analy'sis 328 Alkaloids, Amylaceous and Saccharine Sub- stances, Glucosides, Alcohol and Allied Bodies, Albumenoid and Gelatigenous Sub- stances, Pepsine, Fatty Bodies, Resinoid Sub- stances, Coloring-matters 338 Toxicology 418 Examination of Morbid Urine and Calculi . . . 429 Official Galenical Preparations 442 Official Chemical Preparations 444 Quantitative Analysis : — Introductory Remarks 445 Measurement of Temperature 441 Estimation of Weight 452 Weights and Measures 453 Specific Gravity 463 Correction of the Yolume of Gases for Pres- sure AND Temperature 469 Yolumetric Analysis 475 Gravimetric Analysis 497 Dialysis . 537 CONTENTS. XV PAGE Appendix: — Table of Official Tests for Impurities in Pre- parations OF THE British Pharmacopceia . . 541 Saturation Tables 549 The Elements, their Symbols and Atomic Weights 551 Index 553 CHEMISTEY: GENERAL, MEDICAL, AND PHARMACEUTICAL. INTRODUCTION.* The infinite variety of solid, liquid, and gaseous sub- stances of which our earth and atmosphere are composed, may be resolved with more or less difficulty into sixt}- three distinct forms of matter. These are appropriately termed Elements, for by no known means can they be fur- ther decomposed or subdivided. Only a few (such as gold) occur naturally in the uncombined state, but the greater number are combined in so subtle a manner as to conceal them from ordinary methods of observation. Thus none of the common properties of water indicate that it is com- posed of two elements, both gases, but differing much from each other : nor can the senses of sight, touch, and taste, or other common means of examination, detect in their concealment the three elements of which sugar is com- posed. The art by which these and all other compound substances are resolved into their elements, is termed Chemistry, derived possibly from the Arabic word kamai^ to conceal, whence al kimia^ or alchemy, an art which at the time the name alchemy was given had but little more for its object than the transmutation of the baser metals into gold. The art of chemistry also includes the construc- tion of compounds from elements, and the conversion of substances of one character into those of another. The general principles or leading truths relating to the elements, to the manner in which they severally combine, and to the properties of the compound substances formed by their union, constitute the science of chemistry.*}* * Students using this book as a guide in following chemistry prac- tically should read the first three pages, and then commence work by preparing oxygen. t Persons who practise the art and science of Chemistry are known as Chemists, though conventionally the latter name includes those 2 14 NON - METALLIC ELEMENTS. From these few words concerning the nature of the art and science of chemistr3", it will be seen that in most of the occupations that engage tlie attention of man chemistry plays an important part — in few more so than in the prac- tice of Therapeutics* and Pharmac3\f Air, water, food, drugs, and chemicals, in short all ma- terial substances, are composed of a few elements. An intimate knowledge^of the properties of these, and of the various substances the3"form by combining with each other, a knowledge of the power or force (the chemical force, or chemical affinit3^) by which the elements contained in those compounds are held together, and an application of such knowledge to Pharmac3’ and Medicine, must be the objects sought to be attained by the learner, for whom this work has been especially written. The Elements . — Of the sixt3^-three known elements thirt3^- nine are of medical or pharmaceutical interest ; of these, about two-thirds are metals, and one-third non-metals: the remainder are so seldom met with in nature as to have received no practical application either in medicine, art, or who simply deal in chemicals. Hence have risen the distinguishing appellations of Analytical, Pharmaceutical, and Manufacturing Che- mists. The compounder of medicine is by common consent a chemist only because he is constantly engaged in operations with chemical substances used as remedial agents, his moral right to the name depending on the amount oL chemical knowledge he possesses con- cerning those substances. If he keep an open shop, lie is in Great Britain known as a Chemist and Druggist^ his higher title being Phar- maceutical Chemist ; these respective designations he legally assumes on passing the Minor and Major Examinations, conducted by the Pharmaceutical Society of Great Britain in accordance with the pro- visions of the Pharmacy Acts of 1852 and 18(18. These classes are frequently spoken of collectively as Pharmaceutists, a term also used in the United States. * Therapeutics (0epa7r£uT(xo?, therapeutikos, from Bepamviu, therapeuo, to nurse, serve, or cure) is that branch of medicine which treats of the application of remedies for diseases ; it includes dietetics. The therapeutist also takes cognizance of hygiene, that department of me- dicine which respects the preservation of health. f Pharmacy (from ipap/txctKov, pharmakon, a drug) is the generic name for the operations of preparing or compounding medicines, whether performed by the Medical Practitioner or by the Chemist and Druggist. It is also sometimes applied, like the corresponding term ^Surgery,’ to the apartment in which the operations are conducted. OXYGEN. 15 manufacture. Before intimately studying the elements, it is desirable to acquire some general notions concerning them : such a Jrrocedure will also serve to introduce the practical student to his apparatus, and make him better acquainted wdtli the various methods of manipulation.* Metallic Elements . — With regard to the metallic ele- ments, it may be safely assumed thakthe reader has suffi- cient knowledge for present purposes ; but little, therefore, need now be said respecting them. He has an idea of the appearance, relative w^eight, hardness, etc., of such metals as gold, silver, copper, lead, tin, zinc, and iron. If he has not a similar knowledge of mercury, antimony, arsenicum, platinum, nickel, aluminium, magnesium, potassium, and sodium, he should commence his studies by seeing and handling specimens of each of these metals. Non-Metallic Elements .’\ — With regard to the non-me- tallic elements, it is here supposed that the student has no general knowledge. He should commence his studies therefore by a series of operations as follows, on eight out of their number. OXYGEN. Preparation . — As oxygen is the most abundant element in nature, forming, though in a combined state, about one-half of the whole weight of our globe, it may safely be assumed that this element can readily be obtained in the free condition in a state of purity. In fact, the air itself contains about one-fifth of its bulk of oxygen, though that element cannot be separated sufficiently easily and readily for experimental purposes. It is preferable to apply heat — that force which will often be noticed as antagomstic, so to speak, to chemical union.; heat generally separating particles of matter further from each other, while chemical attraction tends to bind them closer together — it is better to heat certain compounds containing oxygen ; * This allusion to apparatus need not discourage the youngest pupil. With the aid of a few phials, wine-glasses, or other similar vessels always at hand, he may, by studying the following pages, learn the chemical reactions which are constantly occurring in the course of making up medicines, understand the processes by which medicinal preparations are manufactured, and detect adulterations, impurities, or faults of manufacture. Among the substances used in medicine, will be found nearly all the chemicals required. If, in addition, a dozen test-tubes, and a few feet of glass tubing be procured, many of the experiments described may be performed. For full lists of ap- paratus and chemicals see introductory pages. t These bodies are sometimes termed metalloids (from fXEraXXoVf metallon, a metal, and eidos, likeness); but the name is not ap- propriate, for the non-metallic elements have no likeness to metals. 16 NON-?»IETALLTC ELEMENTS. the latter is then evolved in its normal, natural condition of gas. Several substances, when heated, yield oxygen ; but, for convenience and economy, the crystalline body known as chlorate of potassium is best fitted for the experiment. The size and form of the vessel in which to heat it will mainly depend on the quantity required; but for the purposes of the student the best is a test-tube, an instrument in constant requisition in studying practical chemistry. It is simply a thin tube of glass, a few inches in length, and half or three-quarters of an inch in diameter, closed by fusion at one end. It is made of thin glass, in order that it may be rapidly heated or cooled without risk of fracture. Outline of the Pi'ocess. — Heat chlorate of potassium (say, as much as will lie on a shilling) in a test-tube, by means of a spirit- or gas-flame ; gaseous oxygen is quickly evolved. Before applying heat, however, provision should be made for collecting the gas. Collection of Gases, — Procure a piece of glass tubing about the thickness of a quill pen, and a foot or eighteen inches long, and fit it accurately to the test-tube by means of a cork. (Longer tubes may be neatly cut to any size by smartly drawing the edge of a triangular file across the glass at the required point, then clasping the tube, the scratch being between the hands, and pulling the portions asunder, force being exerted in a slightly curved direction so as to open out the crack which the file has commenced.) The tube is fixed in the cork through a round hole made by the aid of a red-hot wire, or, better, a rat-tail file, or, best of all, by one of a set of cork-borers — pieces of brass tubing sharpened at one end and having a flat head at the other. Setting aside the test-tube for a few minutes, pro- ceed to bend the long piece of tubing to the most conve- nient shape for collecting the gas. To bend Glass^ Tubes, — Hold the part of the tube re- quired to be bent in any gas- or spirit-flame (a fish-tail gas- jet answers very well), constantl}' rotating it, so that about an inch of the glass becomes heated. It will soon be felt to soften, and will then, yielding to the gentle pressure of the fingers, assume an}- required angle. In the present case, the tube should be heated at about four inches from the extiemity to which the cork is attached, and bent to an angle of about 90 degrees. Source of Heat . — The source of heat for the test-tube may be the flame of an ordinary s])irit-lamp, or, still better where coal-gas is procurable, a mixture of the latter with air. The simple flame of a common argand gas-burner is preferred by some operators, especially OXYGEN. 11 when the usual gas chimney is replaced by a metal one about four or five inches long. If a piece, or cap, of wire gauze be fixed on to the top of the metal chimney, then the unlit gas which issues from the jets of the argand burner become mixed with air inside the chimney, and the mixture, when lit on the outer side of the gauze, burns with a flame as smokeless and as little colored as that of a spirit-lamp. Gas-lamps especially constructed to burn a mixture of coal-gas and air are sold by chemical-apparatus manufacturers. Collection^ etc. {continued).-— Yit the cork and bent tube into the test-tube; the apparatus will then be ready for delivering gas at a convenient distance from the heated portion of the arrangement. To collect it, have ready three or four test-tubes (or small wide-mouthed bottles) filled with water, and inverted in a basin, or other similar vessel, also containing water, taking care to keep the mouths of the tubes a little below the surface. Now apply heat to the chlorate contained in the test-tube, and so arrange the open end of the bent tube under the water that the gas which presently issues may bubble into and gradually fill the inverted test-tubes. The first tubeful may be rejected, as it probably consists of little more than the air originally in the apparatus, and w'hich has been displaced by the oxygen. That which comes afterwards will be pure oxygen. As each tube or bottle is collected, the mouth (still under the surface of the water) may be closed by a cork and set aside ; or a little cup (such as a porcelain crucible or small gallipot) may be brought under the mouth, and the cup, with the mouth of the tube in it, be lifted out of the water and placed close by till wanted, the water re- maining in the cup efiectually preventing the gas from escaping. On the large scale, oxygen may be made in the same way, larger vessels (glass flasks or iron bottles) being employed. Less heat also will be necessary if the chlorate of potassium be previously mixed with very fine sand, or, still better, with about an equal weight of common black oxide of manganese. Note on the Collection and Storage of Gases . — It may be as well to state that nearly all gases, whether for experimental or practical purposes, are collected and stored in a similar manner. Even coal-gas is generated at gas-works in iron retorts very much the shape of test-tubes, only they are as many feet long as a test- tube is inches ; and the well-known gigantic gas-holders may be viewed as inverted iron test-tubes of great diameter. : Properties . — Oxygen is a colorless gas. It cannot be f liquefied or solidified. Obviously it is not very soluble 2 * 18 NON - METAL Lie ELEMENTS. in water, or it could not be collected by the aid of that liquid. Oxygen is soluble to a certain extent, however (about 3 volumes in 100, at common temperatures), or fishes could not breathe. Other noticeable features are its want of taste and smell. ]Sext, to show the relation of ox^^gen to combustion, re- move one of the tubes from the water b}" placing the thumb over its mouth, apply for a second a lighted wood match to the orifice ; the gas will be found to be incom- bustible. Extinguish the flame of the match, and then quickly introduce the still incandescent carbonaceous ex- tremity of the wood halfway down the test-tube ; the wood will at once burst into flame, owing to the extreme vio- lence with which oxygen supports combustion. These tests of the presence of oxygen may also be applied at the extremity of the delivery-tube whilst the gas is being evolved. (It is desirable to retain two tubes of the gas for use in subsequent experiments ; also one tube in which only one-third of the water has been displaced by oxygen.) Relation of Oxygen to Animal and Vegetable Life . — Not only the carbon at the end of a piece of charred wood, but any other substance that will burn in air (which, as will be seen presently, is diluted oxygen) will burn more brilliantly in pure oxygen. The warmth of the body of animals is kept up by the continuous burning of the carbonaceous matter of the blood in the oxygen of the air drawn into the lungs. The product of this combustion- is a gaseous compound of carbon and oxygen termed carbonic acid gas, a gas which, in sunlight, is decomposed in the cells of plants with fixation of the carbon and liberation of the oxygen ; hence the atmosphere is kept constant in composition. Memorandum . — At present it is not advisable that the reader should trouble himself with the consideration of the chemical action which occurs either in the elimination of oxygen from its compounds, or in the separation of any of the following non-metallic elements from their combinations. It is to the properties of the elements themselves that he should restrict his attention. Working thus from simple to more complex facts, he will in due time find that the com- prehension of such actions as occur in the preparation of these few elements will be easier than if he attempted their full study now. HYDROGEN. Preparation and Collection , — The element of hydrogen is also a gas,* and is obtainable from its commonest com- * Graham obtained alloys of hydrogen with palladium and oth«r metals, compounds in which several hundred times its bulk of gas HYDROGEN* 19 pound, water (of which one-ninth by weight is hydrogen), i)y the agency of hot zinc or iron, but more conveniently by the action of either of these metals on cold diluted sul- phuric acid. The apparatus used for making oxygen may be employed for this experiment ; but no lamp is required. Place several pieces of thin zinc* in the generating-tube, or in any common glass bottle, and cover them with water. The collecting-tubes (these may be wide-mouthed bottles) being ready, add strong sulphuric acid (oil of vitriol) to the zinc and water, in the proportion of about 1 volume of acid to 5 of water, and fit on the delivery-tube ; the hydrogen is at once evolved. Having rejected the first portions (or having waited until the air originally in the bottle may be considered to be all expelled), collect four or five tubes of the gas in the manner described under Oxygen. In making larger quantities bottles of appropriate size may be employed. Other metals, notably potassium and sodium, liberate hydrogen the moment they come into contact with water; but the processes are not economical. Properties — Like oxygen, h^^drogen is invisible, inodor- ous, and tasteless. If made with iron it has a strong smell, but this is due to impurities contained in the metal. Apply a flame to the mouth of the delivery tube (care being taken that the gas is coming off briskl}" — a guaran- tee that no air remains in the generating vessel) ; ignition of the hydrogen ensues, showing that, unlike oxygen, it is combustible. Immerse a lighted match into a tube (or wide-mouthed bottle) containing hydrogen ; the gas is ignited, but the match becomes extinguished. This shows that hydrogen is not a supporter of combustion. is retained by tlie metal in vacuo or even at a red beat. This is physical confirmation of the opinion long held by chemists, that hydrogen is a gaseous metal. Graham termed it hydrogenium (other chemists hydrium), and considered ’ its relative weight in the solid state to be nearly three-fourths that of water. * The best form is granulated zinc {Zincum Granulatum, B. P.) made by heating scraps of common sheet zinc in a ladle over a fire, and as soon as melted pouring, in a slow stream, into a pail of water from a height of 8 or 10 feet. Each drop of zinc thus yields a thin little bell, which, for its weight, presents a large surface to the action of the acid water. If the zinc is allowed to become hotter than ne- cessary, the little bells will not be formed. 20 NON - METAL Lie ELEMENTS. Hydrogen in burning unites with the oxygen of the air and forms water, wdiich may be condensed on a cool glass or other surface. Prove this by holding a glass vessel a few inches above a hydrogen-flame. In burning the h3^dro- gen contained in one of the tubes or bottles, the flame is best seen when the tube is held mouth upwards, and water poured in so as to force out the gas gradualljL If, instead of this gradual combination of the two ele- ments oxj^gen and h^^drogen, they be mixed together in the right proportions and then ignited, the}^ will rapidly combine, in other words, explosion results. Prepare a mix- ture of this kind b^^ filling up with hj’drogen a test-tube from which one-third of the water has been expelled by oxj^gen. Remove the tube from the w^ater, placing a finger over the mouth, and, having a lighted match read}^, appl^^ the flame; a slight explosion will result, owing to the in- stantaneous combination of the two elements, and the ex- pansive force of the steam produced. If an^dhing larger than a test-tube is emplo^^ed in this experiment, it should be a soda-water bottle, or some such vessel equally strong. These two gases thus unite at a temperature considerably above that of boiling water, two volumes of hydrogen and one of oxygen yielding two volumes of gaseous water (true steam). The noise of such explosions is caused by concussion between the particles of the gaseous body and those of air. The force of the explosion, or, in other words, the expansive force of the highly-heated steam produced, is exceedingly slight, certainly very far below that necessary to break the test-tube. Some force, however, is exerted, and hence the necessity of the precaution pre- viously suggested of allowing all the air which may be in a hydro- gen-apparatus to escape before proceeding with the experiments. If a flame be applied to the delivery-tube before all the air is expelled, the probable result will be ignition of the mixture of hydrogen and oxygen (of the air) and consequent explosion. But even in this case the generating-vessel is not often fractured unless it be large and of thin glass, the ordinary effect being that the cork is blown out, and the delivery-tube broken on falling to the ground. Hydrogen is a prominent constituent of all the substances used for producing artificial light, such as tallow, oil, and coal-gas. The ex- plosive force of large quantities, such as a roomful, of coal-gas and air, though vastly below that of an equal weight of gunpowder, is well known to be sufficient at least to blow out that side of the room which offers least resistance. The composition of ivater can be proved analytically as well as synthetically, a current of electricity decomposing it into its con- stituent gases, twice as much hydrogen as oxygen, by volume, being produced. HYDROGEN. 21 Combustion (from comhuro, to burn). — The experiments with hydrogen and oxygen illustrate the true character of combustion. Whenever chemical combination is sufficiently intense to be accom- panied by heat and light, the materials are said to undergo combus- tion. Combustion only occurs at the line of contact of the combining bodies ; a jet of oxygen will burn, in an atmosphere of hydrogen quite as easily as a jet of hydrogen in oxygen. A jet of air (diluted oxygen) will burn as readily in a jar of coal-gas as a jet of coal-gas burns in air ; each is combustible, each supports the combustion of the other. Hence the terms combustible and supporter of combus- tion are purely conventional, and only applicable so long as the cir- cumstances under which they are applied remain the same. In the case of substances burning in air, the conditions are, practically, always the same; hence no confusion arises from regarding air as the great supporter of combustion, and bodies which burn in it as being combustible. Structure of Flame.- — A candle-flame or oil-flame is a jet of gas intensely heated ; the central portion is unburnt gas ; the next envelope is formed of partially burnt and very dense gaseous particles heated sufficiently high to give light, and the outer cone of completely burnt gases. Air made, by any mechanical contrivance of burner, to mix with the interior of a flame at once burns up, or perhaps prevents the formation of dense gases, giving a hotter, but non-luminous, jet. The “Bunsen” gas-burners commonly used in chemical laboratories are constructed on this principle : their flame has the additional advan- tage of not yielding a deposition of soot. In the Bunsen gas-burner a mixture of gas and air passes along a pipe. It only burns at the end, and not within the pipe, because the metal of the burner, by conducting heat aw^ay, cools the mixture below the temperature at which it can ignite. The Davy safety- lamp acts on the same principle : a wire-gauze cage surrounds an oil- flame ; an inflammable mixture of gas (fire-damp) and air can pass through the gauze and catch fire and burn inside ; but the flame cannot be communicated to the mixture outside, because the metal of the gauze and other parts cools down the gas below the tempera- ture at which it can burn. Properties (continued ). — Hydrogen is the lightest sub- stance known. It Avas formerly used for filling balloons, but was soon superseded by coal-gas. Coal gas is not so light as hydrogen, but is cheaper and more easily obtained. The lightness of hydrogen may be rendered evident by the following experiment : Fill two test-tubes with the gas, and hold one with its mouth downwards and the other with its mouth upwards. The hydrogen will have escaped from the latter in a few seconds, whereas the former will still contain the gas after the lapse of some minutes. This may be proved by applying a lighted match to the mouths of the respective tubes. 22 NON-METALLIC ELEMENTS. The relative weight or specific gravity of oxygen is sixteen times that of hydrogen. A vessel holding one grain of hydrogen will hold sixteen grains of oxygen. The relation of the weight of hydrogen to air is as 1 to 14.44 or as 0.0693 to 1.0. One grain of hydrogen by weight would measure about 27 fluidounces. Mem, — It is desirable to retain two tubes of hydrogen for use in subsequent experiments. Diffusion of Gases, — Hydrogen cannot be kept in such vessels as the inverted test-tube ; for, though much lighter than air, it diffuses downwards into the air, while the air, though much heavier, diffuses upwards into the hydrogen. This power of diffusion is character- istic of all gases, and proceeds according to a fixed law, namely, “ in inverse proportion to the square root of the specific gravity of the gas” (Graham). Thus hydrogen diffuses four times faster than oxygen. PHOSPHORUS. Appearance and Source, — Phosphorus [Phosphorus, B. P. and U. S. P.) is a solid element, in appearance and consistence resem- bling white wax ; but it gradually becomes yellow by exposure to light. It is a characteristic constituent of bones, and is always pre- pared from that source by a process which will be subsequently described. Caution, — Phosphorus, on account of its great affinity for oxygen, takes fire very readily, and should therefore be kept under water. When wanted for use it must be cut under water. It is employed in tipping lucifers, though red or amorphous phosphorus [vide Index) is least objectionable for this purpose. Properties , — Dry a piece about one-fourth the size of a pea by quickly and carefully pressing it between the folds of porous (filter or blotting) paper; place it on a plate, and ignite b}^ touching it with a piece of warm wire or wood. Observe that the product of combustion is a dense wdiite smoke, which must be confined at once by^ placing an inverted tumbler, test-glass, or other similar vessel over the phosphorus. The fumes rapidly aggregate, and fall in white flakes on the plate. When this has taken place, and the phosphorus is no longer burning, moisten the powder with a drop or two of water, and observe that some of the water is converted into steam, an effect duetto the intense affinity^ with which the two combine. The powder produced by the combustion of phosphorus is phos- phoric anhydride ; the combination of the latter with the elements of water produces a variety of phosphoric acid which dissolves in the water, forming on standing a dilute solution of ordinary phosphoric acid. The Diluted Phosphoric Acid of the British and United States Pharmacopoeias is a somewhat similar solution, made, however, in a different way, and of a definite strength. NITROGEN. 23 NITROGEN. Source . — The chief source of this gaseous element is the atmo- sphere, nearly four-fifths of which consists of nitrogen (the remaining fifth being almost entirely oxygen). Preparation . — Burn a piece of dried phosphorus, the size of a pea, in a confined portion of air. The oxygen is thus removed, and nitrogen alone remains. The readiest mode of performing this experiment is to fix a piece of eartlien- ware (the lid of a small porcelain crucible answers very well) on a thin piece of cork, so that it may float in a dish of water. Place the phosphorus on the lid, ignite hy a warm rod, and then invert a tumbler, or any glass vessel of about a half-pint capacity, over the burning phosphorus, so that the glass may dip into the water. Let the arrangement rest for a short time for the fumes of phosphoric anhydride to subside and dissolve in the water, and then decant the gas into test-tubes in the manner already indicated, using a vessel of water of sufficient depth to admit of the glass containing the nitrogen to be turned on one side without air gaining access. Larger quantities are made in the same way. Other combustibles, such as sulphur or a candle, might be used to burn out the oxygen from a given quantity of air, but none answer so quickly and com- pletely as phosphorus ; added to which, the product of their combus- tion would not always be dissolved by water, but would remain with and contaminate the nitrogen. 3Iem . — The statement concerning the composition of the air is roughly confirmed in preparing nitrogen, about one-fifth of the volume of the air originally in the glass vessel having disappeared, its place being occupied by water from the dish. Properties . — Like ox3^gen and h^^drogen, nitrogen is in- visible, tasteless, and inodorous. It is only slightly soluble in water. It is distinguished from all other gases by the absence of any characteristic or positive properties. Apply a flame to some contained in a tube ; it will be found to be incombustible. Immerse a lighted match in the gas ; the flame is extinguished, showing that nitrogen is a rion-sup- IDorter of combustion. The chief office of nitrogen in the air is to dilute the energetic oxygen, a mere mechanical mixture resulting. The chemical com- pounds of nitrogen and oxygen are numerous (;vide Index). The compound formed by the union of nitrogen with hydrogen is gaseous ammonia. 24 NON - METALLIC ELEMENTS. Nitrogen is fourteen times as heavy as hj^drogen. The air is nearly fourteen and a, half (14.44) times as heavy as hydrogen. Its average composition, including minor constituents, which will be referred to subsequently, is as follows : — Composition of the Atmosphere. In 100 volumes. Oxygen 20.61 Nitrogen 77.95 Carbonic acid gas .... .04 Aqueous vapor ...... 1.40 Nitric acid 1 Ammonia > traces. Carburetted hydrogen . . . . ] Sulphuretted hydrogen . . .1 traces in Sulphurous acid j towns. The above proportions are by volume. By weight there will be nearly 23 parts of oxygen to nearly 77 of nitrogen, oxygen being the heavier in the ratio of 16 to 14. Ozone {vide Index) is also said to be a normal constituent of air. CHLORINE. Source . — This element is a gas. Its chief source is common salt, more than half of which is chlorine. Preparation . — About a quarter of an ounce of salt and the same amount of black oxide of manganese are placed in a test-tube with sufficient water to cover them ; on add- ing a small quantity of sulphuric acid, the evolution of chlorine commences. Another Process. — As the action of the sulphuric acid on the salt in the above process is mainly to give hydrochloric acid, the latter acid (about 4 parts) and the black oxide of manganese (about 1 part) may be used in making the gas, instead of salt, sulphuric acid, and black oxide of manganese. This is the process of the British and United States Pharmacopoeias. Larger quantities may be made from hydrochloric acid and black oxide of manganese (about 4 parts to 1) in a Florence flask, fitted with a delivery-tube, the flask being supported over a flame by the ring of a retort stand or any similar mechanical contrivance. Mem. — Flasks and similar glass vessels are less liable to fracture if protected from the direct action of the flame by being placed on a piece of wire gauze 2 to 4 inches square, or on a sand-bath, that is, a saucer-shaped tray of sheet iron, on which a thin layer of sand is placed. Collection and Properties . — Chlorine is a most suflTo- cating gas. Great care must consequently be observed in CHLORINE. 25 experimenting with this element. As soon as its pene- trating odor indicates that it is escaping from the test- tube, the cork and delivery-tube should be fitted on, and the gas allowed to pass to the bottom of another test-tube half filled with water. When thirty or forty small bubbles have passed, their evolution being assisted by slightly heating the generating-tube, the latter should be removed to the cupboard usually provided in laboratories for per- forming operations with noxious gases, or dismounted, and the contents washed away. The water in the collect- ing-tube will now be found to smell of the gas, chlorine being, in fact, soluble in about half its bulk of water. Chlorine-water is official* in the British and United States Pharmacopoeias {Liquor Ghlori^ B. P., Aqua Ghlorinii^ U. S. P.). The Vapor Ghlori, B. P., or Inhalation of Chlorine, is simply moist chlorinated lime so placed that some of the chlorine given off may be inhaled. During these manipulations the operator will have noticed that chlorine is of a light green color. That tint is readily observed when the gas is collected in large vessels. As it is soluble in water (2|- vols. in 1 vol. at 60^ F.), it cannot be economically stored over that liquid. Being, however, nearly twice and a half as heavy as air, it may be collected by simply allowing the delivery-tube to pass to the bottom of the test-tube or dry bottle. The distinctive property of chlorine is its bleaching- power. Prepare some colored liquid by placing a few chips of logwood or other dyeing material in a test-tube half full of hot water. Pour off some of this red decoction into another tube, add a few drops of the chlorine-water, and note how rapidly the red color is destroyed. Chlorine readily decomposes noxious gases, and hence is one of the most powerful of the deodorizers. Used in excess it arrests and prevents putrefaction, hence it is one of the best of disinfectants. * The Pharmacopoeia and all in it are official {office, Fr. from L. officium, an office). There are many things which in pharmacy are officinal (Fr. from L. officina, a shop) but not official. To restrict the word officinal to the contents of a pharmacist’s shop, and to that portion of the contents which is Pharmacopoeial, is radically wrong, and should be avoided. ‘‘An official formula is one given under authority. An officinal formula is one made in obedience to the cus- tomary usage of the shop (officina).. To state that any preparation under the sanction of the Pharmacopoeia is officinal, is a misappre- hension of the meaning of the word.” — Brough, 3 26 NON - METALLIC ELEMENTS. Combination of Hydrogen with Chlorine^ forming Hydro- chloric Acid, — If an opportunity occurs of generating the gas in a closed chamber or in the open air, a test-tube of the same size as one of those in which hydrogen has been retained from a previous operation, is filled with the gas. The hydrogen-tube is then inverted over that containing the chlorine, the mouths being kept together by encircling them with a fin'ger. After the gases have mixed, the mouths of the tubes are quickly in succession brought near a flame, when explosion occurs, and fumes of hydrochloric acid combined with the moisture of the air are formed. The Hydrochloric Acid of pharmacy {Acidum Hydrochloricuin,^ B. P., Acidum Muriaticum,^ U. S. P.) is a solution of the gas (made in a more economical way) in water. The foregoing experiment affords evidence of the powerful affinity of chlorine and hydrogen for each other. Chlorine dissolved in water will, in sunlight, slowly remove hydrogen from some of the water and liberate oxygen. The bleaching-power of chlorine is generally re- ferred to this oxidizing effect which it produces in presence of water ; for dry chlorine does not bleach. Density . — Chlorine is thirty-five and a half times as heavy as hydrogen. SULPHUR, CARBON, IODINE. The physical properties of those elements (color, hardness, weight, etc.) are familiar. Their leading chemical characters will also be understood when a few facts concerning each are made the subject of experiment. Sulphur. — Burn a small piece of sulphur; a penetrating odor is produced, due to the formation of a colorless gas, the same as that formed on igniting a sulphur-tipped lucifer match. This product is a perfectly definite chemical compound of the oxygen of the air with the sulphur. It is termed sulphurous anhy- dride or sulphurous acid gas. Carbon is familiar in the forms of soot, coke, charcoal, graphite (plumbago, popularly termed blacklead), and dia- mond. The presence of carbon in wood, and in other vege- table and animal matter, is at once rendered evident by heat. Place a little tartaric acid on the end of a knife in a flame ; the blackening that occurs is due to the separation of carbon. The black matter at the extremity of a piece of half-burned wood is also carbon. THE ELEMENTS, THEIR SYMBOLS, ETC. 27 Carbon, like hydrogen, phosphorus, and sulphur, has a great affinity for oxygen at high temperatures. A striking evidence of that affinity is the evolution of sufficient heat to make the materials concerned red or even white-hot. When ignited in the dilute oxygen of the air, carbon simply burns with a moderate glow, as seen in an ordinary coke or charcoal fire, but when ignited in pure oxygen, the intensity of its combination is greatly exalted. The product of the combination of the two elements, if the oxygen be in excess, is an in- visible gaseous body termed carbonic acid gas ; if the carbon be in excess, another invisible gas termed carbonic oxide results. Iodine. — A prominent chemical characteristic of iodine is its great affinity for metals. Place a piece of iodine, about the size of a pea, in a test-tube with a small quantity of water, and add a few iron-filings or small nails. On gently' warming this mechanical mixture, or even shaking if longer time be allowed, the color and odor of the iodine disappear; it has chemically combined with the iron; a chemical compound has been produced. If the solution be filtered, a clear aqueous solution of the compound of the two elements is obtained. This compound is an iodide of iron. Its solution, made as above, and mixed with sugar, forms, when of a certain strength, the ordinary Syrup of Iodide of Iron of pharmacy {Syrupus Ferri lodidi, B. P. and IT. S. P.). A strong solution mixed with sugar and liquorice- root (sugar, liquorice, liquorice-root, gum Arabic, and reduced iron, U. S. P.) constitutes the corresponding Pill [Pilida Ferri lodidi^ B. P. and U. S. P.). The solid iodide [Ferri lodidiim, B. P.) is obtained on removing the water of the above solution by evaporation. Sulphur and Iron, also, when very strongly heated, chemically com- bine to form a substance which has none of the properties of a mix- ture of sulphur and iron, that is, has none of the characters of sulphur and none of iron, but new properties altogether. The product is termed Sulphide of Iron. Its manufacture and uses will be alluded to in treating of the compounds of iron : it is mentioned here as a simple but striking illustration of the difference between a chemical compound and a mechanical mixture. THE ELEMENTS, THEIR SYMBOLS, Etc. From the foregoing statements a general idea will have been obtained of the nature of several of the more frequently occurring elements. Some additional facts concerning them may be gathered from the following Table, which gives the name in full, the symbol (or short-hand character*) of the name, and its origin. * The symbol is also much more than the short-hand character, as will be presently apparent. 28 THE ELEMENTS, THEIR SYMBOLS, ETO. For the purposes of study the elements may be divided into three classes, viz., those frequently used in pharmacy, those seldom, and those never used. Name. Symbol. Derivation of Name. Oxygen 0 From ofu? (oxus) acid, and yivia-iti (gene- sis) generation, i. e., generator of acids. It was supposed to enter into the composition of all acids when first discovered. Hydrogen H From v^oop (liudor) water, and yivsa-i^ (ge- nesis) generation, in allusion to the product of its combustion in air. Nitrogen N From vhpov (nitron), and yina-i^ (genesis), generator of nitre. Carbon C From carho, coal, which is chiefly carbon. Chlorine Cl From ;s(^x«po?*(chloros) green, the color of this element. Iodine I From lov (ion) a violet, and (eidos) likeness, in reference to the color of its vapor. Sulphur s From sal a salt, and (pur) fire, indi- cating its combustible qualities. Its com- mon name, brimstone, has the same mean- ing, being the slightly altered Saxon word hrynstone, i. e., burnstone. (phos) light, and [analuo), I resolve. Hydrate of Potassium. Caustic Potash. First Synthetical Reaction . — Boil together, for a few minutes, in a test-tube, five or six grains of carbonate of potassium (K.^COg) and a like quantity of slaked lime (Ca2HO) with a small quantity of water. Set the mixture aside in the test-tube rack till all solid matter has subsided. This liquid is a solution of caustic potash, or hydrate of potassium (KHO). Made of a prescribed strength, it forms the Liquor Po- tassce, B. P. (5.84 per cent.), and U. S. P. (5.8 per cent.). The mixture is known to be boiled long enough when a little of the clear liquid, poured into another test-tube and warmed, gives no effervescence on the addition of an acid (sulphuric, hydrochloric, or acetic) — a test whose mode of action will be explained hereafter. Best method of expressing decompositions. — This will be easy of comprehension if what has already been stated concerning symbols and formula on pages 27 to 40, has been carefully and thoughtfully considered. The best means of showing on paper the action which occurs when chemical substances attack each other is by the employ- ment either of equations or diagrams. In an equation the formulae of the salts used are WTitten on one line, the sign of addition (+) intervening ; the sign of equality (=) follows, and then the formulae of the salts produced also separated by a plus sign (-|-). Thus K^COg -f- Ca2HO = 2KIPO -f CaCOg. In this reaction (the operation just performed) the metals of the two salts change places : from K.^OOg and Ca2IIO there are produced 5* 54 ‘ THE METALLIC RADICALS. CaCO.^ and KUO (two molecules); from carbonate of potassium and hydrate of calcium there result carbonate of calcium (the insoluble portion) and hydrate of potassium (in solution). In constructing a diagram, or pictorial illustration, of a chemical reaction, first the formulae of the salts used are written under each other on the left side of a leaf of a note-book; secondly, on the right are written the formulae of the salts produced ; thirdly, the paths which may be supposed to be taken by the respective elements are indicated by the use of brackets and lines, as follows : — 2 KHO CaC 03 It will be noticed that the only important data required in making either equationary or diagrammatic notes of decompositions are the symbolic formulae of the various compounds employed or produced. These formulae are, in this manual, given whenever necessary. (Chem- ists obtain them in the first instance by the help of quantitative analysis.) Note on Nomenclature. — Hydrates are bodies indirectly or directly derived from water by 'one-half of its hydrogen becoming displaced by an equivalent quantity of another radical. Thus, a piece of potassium thrown on to water (HHO) instantly liberates hydrogen, hydrate of potassium (KHO) being formed. The temperature pro- duced at the same time is sufficiently high to cause ignition of the hydrogen, which burns with a purple flame (owing to the presence of a little vapor of potassium), while the hydrate of potassium remains dissolved in the bulk of the water. Water might be termed hydrate of hydrogen. Explanation . — With regard to the groups of atoms represented by the symbols CO3 and HO, only a few words need be said here. The former (CO3) is the grouping (root or radical) found in all car- bonates; it is termed the carbonic radical, and is as characteristic of carbonates as potassium (K) is of potassium salts. HO (hydroxyl) is characteristic of all hydrates. CO3 is a bivalent root, HO univa- lent; hence CO3 is found united with two univalent atoms, as in carbonate of potassium, one bivalent atom, as in carbonate of calcium, CaCOg; and HO is found united in single proportion with univalent atoms as in hydrate of potassium, KIIO, or in double proportion with bivalent atoms as in hydrate of calcium, Oa2HO. The quantivalence of a metal has only to be learnt, and the formulm of its carbonate and hydrate are ascertained without seeing the formula of either. The formulae of all other metallic salts are constructed on the same principle. But, beyond committing to memory the formulae and quantivalence of the various groupings characteristic of carbonates, hydrates, nitrates, sulphates, acetates, etc. (see the following Table), special attention should not at present HYDRATE OP POTASSIUM. 55 be devoted to the subject of the constitution of salts, but restricted .to what may be called the metallic or basylous side of salts. The formulae and quantivalence of the chief acidulous groupings referred to and the symbols and quantivalence of allied elementary bodies are included in the following table : — Formulce and Quantivalence of Acidulous Radicals. All chlorides contain “ bromides “ “ iodides “ “ cyanides “ “ hydrates “ “ nitrates “ “ chlorates “ “ acetates “ “ oxides “ “ sulphides “ “ sulphites “ “ sulphates “ “ carbonates “ “ oxalates “ “ tartrates “ “ citrates “ “ phosphates “ “ borates “ . Cl I . Br . I . NO . HO • NO, . CIO, . 0,H,0,. • 0 ) . s ■ so, • so, 1- • CO, . c,o. • C,H,0, J • C,H,0, ) • BO, ] p a o gs p I — I O ^ • r+- •-j H Radicals . — The above elements and compounds are termed radi- cals, each being the common root [radix) in a series of salts. Why compound radicals (as NO^, SO4, PO4, etc.) differ in quantivalence cannot well be explained. Their constituent atoms doubtless always exert the same amount of attractive force, nearly but not quite all this force being exerted in retaining the atoms in one group, and the remainder probably determining the quantivalence. Some of the compound radicals are obtainable in the free state, others have yet to be proved capable of isolated existence.* Pure Solution of Potash . — Solution of potash generally contains a trace of alumina dissolved from the lime by the hot alkali, but not enough to interfere with the use of the liquid in medicine. If the solution is required for analytical purposes, it may be obtained free from alumina by avoiding the employment of heat, in the manner suggested by Kedwood. Half a gallon is made by mixing half a pound of slaked lime with about three pints of water, placing the mixture in a half-gallon bottle (Winchester quart), and adding to it, in small quantities at a time, a solution of half a pound of carbonate of potassium dissolved in the other pint of water, shaking the mixture well for several minutes after each addition. The whole is now set on one side till clear; and then, if a small quantity poured into a * A few modern authors term these roots radichs, a form of the word more usefully expressive of little roots or rootlets. 56 THE METALLIC RADICALS. test-tube and warmed does not effervesce on the addition of hydro- chloric acid, the solution is fit for use. If effervescence (carbonic acid gas) occurs, the mixture must be again well shaken. If the lime be good and recently slaked, and the bottle violently shaken once every half-hour, the decomposition will be complete in about ten or twelve hours. Liquor Potassce is officially directed to be made as follows : — Dissolve 1 pound of carbonate of potassium in one gallon of water; heat the solution to the boiling-point in a clean iron vessel, gradually mix with it 12 ounces of slaked lime, and continue the ebullition for ten minutes with constant stirring. Then remove the vessel from the fire ; and when by the subsidence of the insoluble matter the super- natant liquor has become perfectly clear, transfer it by means of a siphon or by decantation to a green-glass bottle furnished with an air-tight stopper, and add distilled water, if necessary, to make it correspond with the tests of specific gravity and neutralizing-power. The method of applying these tests will be explained in subsequent sections. Solid Potash. — Solution of potash evaporated to dryness in a silver or clean iron vessel and the residue fused and poured into moulds constitutes Potassa Caustica, B. P.; Potassa, U. S. P. It often contains chloride and sulphates, detected by nitrate of silver and a barium salt, as described subsequently in connection with hydro- chloric and sulphuric acids. Potassa cum Calce, U. S. P., is a grayish-white powder, made by rubbing together equal weights of solid potash and quicklime. Sulphurated Potash. Second Synthetical Reaction . — Into a test-tube put a few grains of carbonate of potassium previously mixed with half its weight of sulphur. Heat the mixture gradually until it ceases to effervesce. The resulting fused mass poured on a slab and quickly bottled is the Potassa Sul- phurata.^ Sulphurated Potash, of B. P.,or the Potassii Sul- phuretum^ U. S. P. 3K,CO, + 4S., = K.,SA + 2Iv,S 3 -f SCO, Carbonate of Sulphur. Hyposulphite Sulphite of Carbonic potassium. of potassium. potassium. acid gas. As met with in pharmacy this salt is not a single definite chemical compound, but a mixture of several, in short, its chemical charac- ter is well indicated by its vague name. When fresh, and if care- fully prepared with the official proportions of dry ingredients, it is of the color of liver (whence the old name “liver of sulphur”), and consists, as shown by Watts, of the salts mentioned in the fore- going equation, together with a little undecomposed carbonate of potassium, with perhaps higher sulphides of potassium (K,S^ and K.^Sj) ; but rapidly absorbing oxygen from the air it soon becomes green and yellow, sulphite (K.^SOg) and sulphate of potassium (K.,SOJ formed, and ultimately a useless mass of a dirty-white ACETATE OF POTASSIUM. 57 color results, consisting of sulphate and hyposulphite, with generally some carbonate of potassium and free sulphur. Moreover, if over- heated in manufacture the hyposulphite 4(K2S203) is decomposed into sulphate 3(K2S04) and sulphide of potassium. Recently made, “ about three-fourths of its weight are dissolved by rectified spirit.^' It is occasionally employed in the form of ointment. In preparing large quantities of sulphurated potash, the test-tube is replaced by an earthenware vessel termed a crucible (from crux, a cross, for originally a cross was impressed upon the melting-pot as used by alchemists and goldsmiths ; others derive the word from crux an instrument of torture, the sense here being symbolical). Heating Crucibles . — Crucibles of a few ounces’ capacity may be heated in an ordinary grate-fire. Larger ones require a stove with a good draught — that is, 2i furnace. Even the smaller ones are more conveniently and quickly heated in a furnace. Half-ounce or one ounce experimental porcelain crucibles may be heated in a spirit- or gas-flame ; the air gas-fiame already described being generally the most suitable. Acetate of Potassium. Third Synthetical Reaction. — Place ten or twenty grains or more of carbonate of potassium in a small disli, and saturate (satur^ full) with acetic acid ; that is, add acetic acid so long as effervescence is thereby produced ; the re- sulting liquid is a strong solution of acetate of potassium. Evaporate most of the water, stirring with a glass rod* to promote the evolution of vapor; a white salt remains which fuses on the further application of heat : this is the official Acetate of Potassium (Fotassae Acetas^ B. P., and Potassii Acetas^ U. S. P.). If fused in the open vessel the acetate is liable to become slightly charred and discolored ; this is prevented by transferring the solid residue to a test- tube or florence flask before finally fusing. It forms a wdiite deliquescent foliaceous satiny mass, neutral to test-paper, and wholly soluble in spirit. A ten per cent, solution in water forms the ‘‘Solution of Acetate of Potash, B. P. K,CO, + 2HC2H3O2 = 2KC2H3O2 + H2O + CO2 Carbonate of Acetic Acetate of Water. Carbonic potassium. acid. potassium. acid gas. Explanation of Formulce . — The formula for one molecule of ace- tic acid (the acetate of hydrogen) is HC2H3O2, and one of acetate of potassium KC2H3O2. The grouping, C2H8O2, is characteristic of all * Glass rod is usually purchased in the form of long sticks. The pieces may be cut to convenient lengths of from 6 to 12 inches {vide p. 16 ), sharp ends being rounded off by holding in a flame for a few minutes. 58 THE METALLIC RADICALS. acetates ; it is univalent, and may be shortly, though less instruc- tively, written A. Explanation of Process. — When two molecules of acetic acid (2110^11302) and one of carbonate of potassium (K2CO3) react, two molecules of acetate of potassium (2KO2H3O2) and one of carbonic acid (H2CO3) are produced, the latter at once splitting up into water (H2O) and carbonic acid gas (CO2), as already shown in the equa- tion. Diagram of the Reaction. — The nature of the above operation is indicated by an equation ; it (and all succeeding reactions) should be expressed in the student’s note-book as a diagram, similar to that just given in connection with the first synthetical reaction. In con- structing a diagram, a little reflection concerning the formulae of the bodies produced will show how the symbols in the formulae of the bodies employed are to be arranged on the right-hand side of the brackets. Evaporation of water from a liquid is best conducted in wide shallow vessels rather than in narrow deep ones, as the steam can thus quickly diffuse into the air and be rapidly conveyed away ; hence a small round-bottomed basin is far more suitable than a test- tube for such operations. On the manufacturing scale, iron, or iron lined with enamel, or semiporcelain, copper, tinned copper, or solid tin pans are used. Up to 12 or 18 inches diameter, pans, basins, or dishes, made of Wedgwood w^are or porcelain composition, may be employed. Note. — The above reaction has a general as well as a special syn- thetical interest. It represents one of the commonest methods of forming salts, namely, the saturation of an acid with a carbonate. Carbonates added to acetic acid yield acetates, to nitric acid, ni- trates, to sulphuric acid, sulphates. Many illustrations of this gene- ral process occur in pharmacy. Bicarbonate of Potassium. Fourth Synthetical Reaction, — Make a strong solution of carbonate of potassium by heating in a test-tube a mixture of several grains of the salt with rather less than an equal weight of water. Through the cooled solution pass car- bonic acid gas, slowl}' but continuously ; after a time a w^hite crystalline precipitate of Acid Carbonate or Bicar- bonate of Potassium (KHCO3), Potassii Bicay'honas.^ U. S. P., the Bicarbonate of Potash of the British Pharmacopoeia {Potassii Bicarbonas^ B. P.), will be formed. K2CO3 + H2O -f CO2 = 2KHCO3 Carbonate of Water. Carbonic Bicarbonate potassium. acid gas. of potassium. The carbonic acid gas necessary for this operation is to be pre- pared from marble, though it might be obtained from any carbonate. Thus the previous synthetical reaction could be made available for BICARBONATE OF POTASSIUM. 59 this purpose, the carbonic gas evolved on the addition of the acetic acid to the carbonate of potassium being conducted into a strong solution of more carbonate of potassium by a^lass tube bent and fitted as described when treating of oxygen ^s. But motives of economy induce the use of carbonate of calcium, the form known as marble being always employed. Economy and convenience also cause hydrochloric acid to be used in preference to acetic or any other. Generate the carbonic acid gas by adding common hydro- chloric acid, diluted with twice its bulk of water, to a few fragments of marble contained in a test-tube or small flask, and conduct the gas into the solution of carbonate of potassium by a glass tube bent to a convenient angle or angles, and fitted to the test-tube by a cork in the usual way. The tube may be replenished with marble or acid or both when the evolution of gas is becoming slow. In work- ing on any larger quantity than a few grains of the carbon- ate a wide delivery tube should- be employed, or the end of the narrow tube occasionally cleared from any bicarbonate that may have been deposited in it. The more economical official arrangements of the apparatus employed in this process will be descxfibed under the corresponding sodium salt. Deposition of the Bicarbonate explained. — Bicarbonate of potas- sium is to a certain extent soluble in water ; but as it is less so than the carbonate of potassium, and as a saturated solution of the latter has been used, the precipitation of a part of the bicarbonate inevi- tably occurs. In other words, the quantity of water present is suffi- cient to keep the carbonate, but insufficient to retain the equivalent quantity of bicarbonate in solution. Properties. — Prepared on the large scale, bicarbonate of potassium occurs in colorless, n on-deliquescent, right rhombic prisms ; it has a saline, feebly alkaline, non-corrosive taste. Effervescing Solution of Potash. — A solution of 30 grains of bi- carbonate of potassium in one pint of water, charged with 7 times its bulk (often less) of carbonic acid gas by pressure, constitutes the ordinary “ potash-water,” the so-called Liquor Potassce Effervescens, B. P. Notes on Nomenclature. — The prefix hi- in the name bicarbo- nate of potassium,” serves to recall the fact that to a given amount of potassium thi^ salt contains twice as much carbonic radical as the carbonate. The salt is really a “ carbonate of potassium and hydrogen” (KHCOg) ; it is intermediate between carbonate of potas- sium (K 2 C 0 .{) and carbonate of hydrogen, or true carbonic acid (H.^COg) ; it is “ acid carbonate of potassium” or “ hydric potassium carbonate ;” chemically, though not physically, it is an acid salt. Salts whose specific names end in the syllable a^e” (carbona?^e, sulphate, etc.) are in general conventionally so termed when they 60 THE METALLIC RADICALS. contain an acidulous radical, or the characteristic elements of an acid, whose name ends in “ «c,” and from ’which acid they have been or may be formed, ^'hus the syllable “ ate"' in the words sulpha/^e, nitrate, acetate, carl^na^e, etc., indicates that the respective salts contain a radical whose name ended in ic, the previous syllables, sulph-, nitr-, acet-, carbon-, indicating what that radical was — the sul- phuric, nitric, acetic, or carbonic. Occasionally a letter or syllable is dropped from or added to a word to render the name more eupho- nious ; thus the sulphurif; radical forms sulphates, not sulphurates. Citrate of Potassium. Fifth Synthetical Reaction, — Dissolve a few grains or more of citric acid (HgCgH.O^) in water, and add carbon- ate (bicarbonate, U. S. P.) of potassium until it no longer causes effervescence, and the solution after well stirring is neutral or faintly acid to test paper. The resulting liquid is a solution of citrate of potassium (KgOgH^O^) Liquor Fotassii Citratis,^ D. S. P.). Evaporated to dryness, in an open dish, a pulverulent or granular residue is obtained, which is the oflficial Potassii Citras^ U. S. P., a white deli- quescent powder. 3K.,COg -f -f 3H,0 -f 3CO, Carbonate of Citric acid. Citrate of Water. Carbonic potassium. potassium. acid gas. Citrates. — The citric radical or group of elements, w^hich wdth three atoms of hydrogen forms a molecule of citric acid, and with three of potassium citrate of potassium, is a trivalent grouping; hence the three atoms of potassium in a molecule of the citrate. The full chemistry of citric acid and other citrates will be subsequently described. Nitrate of 'potassium (KNO3) [Potassii Nitras, U. S. P.) and Sulphate of potassium (K 2 SO 4 ) [Potasii Sulphas, U. S. P.) could obviously also be made by saturating nitric acid (HNO3), phuric acid (H 2 SO^), respectively, by carbonate of potassium. Practically they are not made in that w^ay — the nitrate occurring, as already stated, in nature, and the sulphate as a by-product in many operations. Both salts will be hereafter alluded to in connec- tion with nitric acid. Tartrate of Potassium. Sixth Synthetical Reaction, — Place a few grains of car- bonate of potassium in a test-tube with a little water, heat to the boiling-point, and then add acid tartrate of potas- sium (KIIC\II^Og or KHT) till there is no more efferves- cence, and the solution is neutral to test-paper; a solution of neutral tartrate of potassium (K2’T') results, the Potassii POTASSIUM. Gl Tartras of the United States Pharmacopoeia. Crystals (4- or 6-sided prisms) may be obtained on concentrating the solution b}^ evaporation and setting the hot liquid aside. Larger quantities are made in the same way, 20 of acid tartrate and 9 of carbonate (with 50 of water) being about the proportions necessary for neutrality. 2KHC,H,0, + K,C03 = 2K,C,H,03 + H,0 + CO, Acid tartrate of Carbonate of Neutral tartrate Water. Carbonic potassium. potassium. of potassium. acid gas. Tartrates. — C^H^Og are the elements characteristic of all tar- trates ; they form a bivalent grouping ; hence the formula of the hydrogen tartrate, or tartaric acid, is H2C4H40g ; that of the potas- sium tartrate K204H40g; of the intermediate salt, the acid potas- sium tartrate (cream of tartar), KHC^H^Og. If the acid tartrate of one metal and the carbonate of another react, a neutral dimetallic tartrate results, as seen in Rochelle salt (KNaO^H^Og), the Soda Tartrate of the British Pharmacopoeia. [Potassii et Sodii Tartras, U. S. P.) Acid salts [e. g. KHO^H^Og), that is, salts intermediate in compo- sition between a normal or neutral salt (e. g. K204H^Og) and an acid (e. g. H2C4H40g) will frequently be met with. All acidulous radi- cals, except those which are univalent, may be concerned in the for- mation of acid salts. Iodide of Potassium. Seventh Synthetical Reaction. — To a solution of potash, heated in a test-tube, flask, or evaporating-basin, accord- ing to quantity, add a small quantity of solid iodine. The deep color of the iodine disappears entirely. This is due to the formation of the colorless salts, iodide of potassium (KI) and iodate of potassium (KIO^), which remain dis- solved in the liquid. Continue the addition of iodine so long as its color, after a few minutes^ warming and stirring, disappears. When the whole of the potash in the solution of potash has been converted into the salts mentioned, the slight excess of iodine remaining in the liquid will color it, and thus show that this stage of the operation is completed. 6KHO + 31, = 5KI + KIO, -p 3 H 2 O Hydrate of Iodine. Iodide of Iodate of Water. potassium. potassium. potassium. Separation of the Iodide from the Iodate. — Evaporate the above solution to dryness. If both salts were required, the solid mixture might be digested in spirits of wine, which dissolves the iodide, but not the iodate. But the iodide only is used in medicine. Mix the residue, therefore (re- 6 62 THE METALLIC RADICALS. serving a grain or two for a subsequent experiment), with about a twelfth of its weight of charcoal, and gently heat in a test-tube or crucible until slight deflagration ensues.* 2KIO3 + SC, = 2KI 4 - 6CO Iodide of Carbon. Iodide of Carbonic potassium. potassium. oxide. Under these circumstances the iodide remains unaffected, but the iodate loses all its oxygen, and is thus also reduced to the state of iodide. Treat the mass with a little water, and filter to separate excess of charcoal ; a solution of pure iodide of potassium results. It may be used as a reagent or evaporated to a small bulk, and set aside to crystallize. This is the process mentioned in the British and United States Pharmacopoeias [Potassii lodidum). “ Solution of Iodate of Potas- sium/’ is also official as a test-liquid. Properties. — Iodide of Potassium crystallizes in small cubical crystals, very soluble in water, less so in spirit. One part in ten of water forms “ Solution of Iodide of Potassium,” B. P. The addition of charcoal in the above process is simply to facili- tate the removal of the oxygen of the iodate of potassium. Iodate of potassium (KIO3) is analogous in constitution, and in composition, so far as the atoms of oxygen are concerned, to chlorate of potassium (KCIO3), which has already been stated to be more useful than any other salt for the actual preparation of oxygen gas itself. Hence the removal of the oxygen of the iodate might be accomplished by heat- ing the residue without charcoal. In that case the liberated oxygen would be detected on inserting the incandescent extremity of a strip of wood into the mouth of the test-tube in which the mixture of iodide and iodate had been heated. The charcoal, however, burns out the oxygen more quickly, and thus economizes heat and time. Note . — The formula of iodide of potassium (KI) shows that the salt contains potassium and iodine in atomic proportions. A refer- ence to the table of atomic weights at the end of the volume, and a rule-of-three sum, would therefore show what weight of salt is pro- ducible from any given weight of iodine. Detection of Iodate in Iodide of Potassium , — Iodate of potassium remaining as an impurity in iodide of potassium * Deflagration means violent burning, from Jlagratus^ burnt (JlagrOy I burn), and de. a prefix augmenting the sense of the word to which it may be attached. Paper thrown into a fire simply burns, nitre deflagrates. Z>^-tonate (detono) is a precisely similar word, meaning to explode with violent noise. If, in tlie operation of lieating iodate of potassium with charcoal, excess of the latter be employed, slight incandescence rather than dtdlagration occurs ; if the charcoal be largely in excess, the reduc- tion of the iodate to iodide of potassium is effected without visible deflagration or even incandescence. POTASSIUM. 63 may be detected by adding to a solution of the latter salt some tartaric acid, shaking, and then adding mucilage of starch ; blue “ iodide of starch’’ is formed if a trace of iodate be present, but not otherwise. The tartaric acid liberates iodic acid (HIO3) from the iodate of potassium and hydriodic acid (HI) from the iodide of potassium; neither acid alone attacks starch, but by reaction on each other the two give rise to free iodine which then forms the blue color. This experiment should be tried on a sample of pure iodide of potassium and on a grain or two of the im- pure iodide reserved from the previous experiment. HIO 3 + 5 HI == 3H,0 -f SJ,. Note on Nomenclature. — The syllable ide attached to the syllable iod, in the name “ iodide of potassium,” indicates that the element iodine is combined with the potassium. An locate, as already ex- plained, is a salt containing the characteristic elements of iod^c acid and all iodic compounds. Salts one of whose names ends in ide are those which are, or may be, formed from elements. The names of salts which are, or may be, formed from compounds include other syllables, ate being one (see page 59). The only other syllable is ite, which is included in the names of salts which are, or may be, formed from acids and radicals whose names end in ous : thus hypo- sulph^Ye of sodium, etc. To recapituate : A salt, whose name ends in ate contains a compound acidulous radical whose name ends in ic ; a salt whose name ends in ite contains a compound acidulous radical whose name ends in ous ; a salt whose name ends in ide con- tains an element for its acidulous radical. Thus sulph^(ic relates to sulphur, sulph^^e to the sulphurous radical, sulpha^^e to the sulphuric radical, and so on with other “ ides,” “ ites,” or ‘‘ ates.” Bromide of Potassium [Potassii Bromidum, B. P.). — This salt is identical in constitution with iodide of potassium, and may be made in exactly the same way, bromine being substituted for iodine. The formula of bromic acid is HBrOg. It will be noticed that the follow- ing equations are similar in character to those showing the prepara- tion of iodide of potassium. 6KHO + SBrg = 5KBr + KBrOg + 3H,0 Hydrate of Bromine. Bromide of Bromate of Water, potassium. potassium. potassium. 2KBr03 + 3C\ = 2KBr + 6CO Bromate of Carbon. Bromide of Carbonic potassium. potassium. oxide. Potassii Bromidum, U. S. P., is made by decomposing solution of bromide of iron (Fel2) by solution of pure carbonate of potassium (K2OO3), evaporating, and crystallizing. Manganates of Potassium. Eighth Snythetical Reaction , — Place a fragment of solid caustic potash (KHO), with about the same quantity of 64 THE METALLIC RADICALS. chlorate of potassium (KCIO3), and of black oxide of man- ganese (MnO.^), on a piece of platinum foil.* Hold the foil by a small pair of forceps or tongs in the flame of a blow- pipe for a few minutes until the fused mixture has become dark green# This color is that of manganate of potassium (K^MnOJ. GKHO + KCIO 3 + 3MnO, = SK^MiiO, + KCl + 3H,0 Hydrate of Chlorate of Black oxide of Manganate of Chloride of Water, potassium. potassium. manganese. potassium. potassium. Ninth Synthetical Reaction, — Permanganate of Potas- sium (K 2 Mn^Og) {Potassii Permanganas^ U. S. P.), which is purple, is obtained, or rather a solution of it, on placing the foil and its adherent mass in water, and boiling for a short time. SK^MnO, + 2 H 2 O = K^Mn^Og + 4KHO + MnO., Manganate of Water. Permanganate Hydrate of Black oxide potassium. of potassium. potassium, of manganese. On the large scale, the potash set free in the reaction is neutral- ized by sulphuric or carbonic acid, and the solution evaporated to the crystallizing point. Further details will be given in connection with manganese. Solutions of manganate or permanganate of potassium and of sodium so readily yield their oxygen to organic matter, that they are used on the large scale as disinfectants, under the name of “ Condy’s Disinfecting Fluids.” Synthetical Reactions bringing under consideration the remain- ing official compounds (namely, bichromate, arsenite, chlorate, cyan- ide, ferrocyanide, and ferridcyanide of j)otassium) are deferred at present. (&) Reactions having Analytical Interest [Tests). Note. — These are reactions utilized in searching for small quanti- ties of a substance (in the present instance of potassium) in a solution. They are best performed in test-tubes or other small vessels. Each should be expressed, in the form of an equation or diagram, in the student’s note-book. All previous or future equations given in this volume should he transferred to the note-hook in the form of dia- grams similar to that given on page 54. First Analytical Reaction. — To a solution of any salt of * The foil may be 1 inch broad by 2 long. No ordinary flame will melt, or common chemical substance attack platinum ; hence the same piece may be used in experiments over and over again. Metals form a fusible alloy with plaiinum, and phosphorus rapidly attacks it, hence such substances, as well as mixtures likely to yield them, should be heated in a small porcelain crucible. POTASSIUM. 65 potassium (chloride,* for example) add solution of per- chloride of platinum (PtClJ, and stir the mixture with a glass rod ; yellow double chloride of platinum and potas- sium (PtC1^2KCl) will be precipitated.f Explanation. — The precipitate is, practically, insol i!6le in water. It is for this reason that a very small quantity of any soluble potas- sium salt (or, rather, of the potassium in that salt) is thrown out of solution by perchloride of platinum. Precaution. — Only chloride of potassium forms this characteristic compound ; hence, if the potassium salt in the solution is known not to be a chloride, or if its composition is unknown, a few drops of hydrochloric acid must be added, otherwise some of the perchloride of platinum will be utilized for its chlorine only, the platinum being wasted. Thus, if nitrate of potassium (KNO3) be present, a few drops of hydrochloric acid enable the potassium to assume the form of chloride when the perchloride of platinum is added, nitric acid (HNO3) being set free. Memoranda. — Experiments with such expensive reagents as per- chloride of platinum are economically performed in watch-glasses, drops of the liquids being operated on. When the precipitate is long in forming, it is sometimes of an orange-yellow tint. If iodide of potassium happen to be the potassium salt under examination, some iodide of platinum (Ptl4) will also be formed, giving a red color to the solution, and a larger quantity of the precipitant (that is, the precipitating agent) be required. Note on Nomenclature. — When distinct molecules of salts unite and form a single crystalline compound, the product is termed a double salt. The double chloride of potassium and platinum is such a body. Acid Tartrate of Potassium. Second Analytical Reaction, — To a solution of any salt of potassium add some strong solution of tartaric acid (H^C^H^Og), and shake or well stir the mixture ; a white granular precipitate of acid tartrate of potassium (KHC^H^Og) will be formed. Limits of the Test. — Acid tartrate of potassium is soluble in about 180 parts of cold and in 6 parts of boiling water. Hence, in applying the tartaric test for potassium, the solutions must not be hot. Even if cold, no percipitate will be obtained if the solutions are very dilute. This test, therefore, is of far less value than the first mentioned. The * A few fragments of carbonate of potassium, two or three drops of hydrochloric acid, and a small quantity of water, give a solution of chloride of potassium at once, K^C03-|-2HC1=2KC1+H20-|-C02. t By precApitation (from prcecipito^ to throw down suddenly) is simply m»eant the formation of particles of solid in a liquid, no matter whether the s did, the precip'tate, subsides or floats. 6 * 66 THE METALLIC RADICALS. acid tartrate of potassium is less soluble in diluted alcohol than in water ; so that the addition of spirit of wine renders the reaction somewhat more delicate. Cream of Tartar. — The precipitate is the Bitartrate or Acid Tartrate of Potassium, though the official preparation is not formed in the above manner ; on the contrary, the acid is derived from the salt, which occurs naturally in the juice of many plants. Memorandum. — When the tartaric acid is added to the salt of potassium, and the acid tartrate formed, the acid whose chief elements were previously with the potassium is set free ; and in such acid solu- tions the acid tartrate is somewhat soluble. To prevent loss on this account, acid tartrate of sodium, a salt tolerably soluble in water, may be used as a test instead of tartaric acid (Plunkett). The sodium uniting with the acidulous radical, thus gives a neutral in- stead of an acid solution. But this advantage is of less importance from the fact that more water is introduced by the saturated solu- tion of acid tartrate of sodium than by a saturated solution of tar- taric acid. Third Analytical Reaction . — The flame-test. Dip the looped end of a platinum wire 'into a solution containing a potassium salt, and introduce the loop into a spirit-flame, the flame of a mixture of gas and air, a blow^pipe flame, or other slightly colored flame. A light violet or lavender tint will be communicated to the flame, an effect highly’- characteristic of salts of potassium. Fourth Analytical Fact . — Salts of potassium are not volatile. Place a fragment of carbonate, nitrate, or any other potassium salt, on a piece of platinum foil, and heat the latter in the flame of a lamp ; the salt may fuse to a transparent liquid and flow freely over the foil, water also if present will escape as steam, and black carbon be set free if the salt happen to be of vegetable origin ; but the potassium compound itself will not be vaporized. This is a valuable negative propertv, as will be evident when the analytical reactions of ammonium come under notice. QUESTIONS AND EXERCISES. 70. Name the sources of Potassium. 71. Give the source, formula, and characters of Carbonate of Potassium. 72. Distinguish between synthetical and analytical reactions. 73. How is the official Liquor Potassce prepared ? 74. What is the systematic name of Caustic Potash ? 75. State the chemical formula of Caustic Potash. 76. Construct an equation or diagram expressive of the reaction between carbonate of potassium and slaked lime, SODIUM. 6Y 77. Define a hydrate. 78. What group of atoms is characteristic of all carbonates ? 79. Define the term radical. 80. How is “Sulphurated Potash” made, and of what salts is it a mixture ? 81. What is the formula of the acetic radical — the radical of all acetates ? 82. Draw a diagram showing the formation of Acetate of Potas- sium. 83. Give a general process for the conversion of carbonates into other salts. 84. What is the difference between Carbonate and Bicarbonate of Potassium ? How is the latter prepared ? 85. What is the relation between salts whose specific names end in the syllable and acids ending in “ ^c” ? 86. Draw out diagrams or equations descriptive of the formation of Tartrate of Potassium from the Acid Tartrate, and Citrate from the Carbonate of Potassium. 87. Distinguish between a normal and an acid salt. 88. How is Iodide of Potassium made ? Illustrate the process by either diagrams or equations. 89. Describe the appearance and chemical properties of iodide of potassium. 90. How much Iodide of Potassium is producible from 1000 grains of Iodine ? Ans. 1307 grains. 91. Give a method for th^ detection of iodate in iodide of potas- sium. Explain the reaction. 92. Has the syllable “ idd^ any general signification in chemical nomenclature ? • 93. What is the difference between sulphides, sulphites, and sul- phates ? 94. Mention the chemical relations of Bromide to Iodide of Potas- sium. 95. Describe the formation of Permanganate of Potassium, giving equations or diagrams. 96. How do manganate and permanganate of potassium act as disinfectants ? 97. Enumerate the tests for potassium, explaining by diagrams or equations the various reactions which occur. SODIUM. Symbol Na. Atomic weight 23. Formula Na^. Probable molecular weight 46. Memoranda . — Most of the sodium salts met with in Pharmacy are directly obtained from carbonate of sodium, which is now manu- factured on an enormous scale from chloride of sodium (common salt, sea-salt or bay-salt, or rock-salt), the natural source of the sodium salts. When pure, salt [Sodii Chloridum, B. P. and U. S. P.) occurs “ in small white crystalline grains, or transparent cubic crys- 68 THE METALLIC RADICALS. tals, free from moisture the best varieties commonly contain a little chloride of magnesium and sometimes other impurities. Be- sides the direct and indirect use of carbonate of sodium, or carbonate of soda, as it is commonly called in medicine, it is largely used for household cleansing-purposes under the name of “ soda,” and in the manufacture of soap. Nitrate of sodium also occurs in nature, but is valuable for its nitric constituents rather than its sodium. Sodium is a constituent of about forty chemical or Galenical preparations of the Pharmacopoeias. Sodium is prepared by a process similar to that for potassium, but with less difficulty. Its atom is univalent, Na'. Reactions having (a) Synthetical and (6) Analytical Interest. {a) Reactions having Synthetical Interest. Hydrate of Sodium. Caustic Soda. First Synthetical Reaction — The formation of solution of hydrate of sodium or caustic soda, NaHO {Liquor Sodse^ B. P. and U. S. P.). This operation resembles that of making solution of jiotash already described. The practical student should refer to the remarks made concern- ing solution of potash, applying them to solution of soda. He may perform the corresponding experiments or omit them, as he considers he does or does not clearly comprehend all they are designed to teach. Na^COg + Ca2HO = 2NaHO + CaCOj Carbonate Hydrate of Hydrate of Carbonate of sodium. calcium. sodium. of calcium. Pure Solution of Soda, free from any trace of alumina, may be prepared by shaking in a Winchester quart, once every 20 or 30 minutes for 5 or 6 hours, 14 ozs. of crystals of carbonate of sodium and 8 ozs. of good recently slaked lime. The official Liquor Sodce is made from 28 ounces of crystals of carbonate of sodium, 12 of slaked lime, and 1 gallon of water, under precisely similar circum- stances to those detailed for Liquor Potasses (p. 56). If the solu- tion be evaporated to dryness, and the residue fused and poured into moulds, solid hydrate of sodium {Soda Caustica, B. P., Soda, U. S. P.) is obtained. Common and cheap caustic soda is now largely employed in manufactures. It is a by-product in the prepa- ration of carbonate of sodium, and, though highly useful as a chemi- cal agent, is too impure for use in medicine. Action of Sodium on Water. — Sodium, like potassium, decom- poses water with production of hydrate of sodium and hydrogen, but, unless the sodium is confined to one spot, by placing it on a small floating piece of filter-paper, the action is not sufficiently intense to cause ignition of the escaping hydrogen. When the latter does ignite, it burns with a yellow flame, due to the presence of a little vapor of sodium. SODIUM. 69 Second Synthetical Reaction. — The reaction of sulphur and carbonate of sodium at a high temperature resembles that of sulphur and carbonate of potassium ; but, as the product is not used in medicine, the experiment may be omitted. It is mentioned here to draw attention to the close resemblance of the potassium salts to those of sodium. Acetate of Sodium. Third Synthetical Reaction. — Add the powder or frag- ments of carbonate of sodium (NugCOg) to some strong acetic acid in a test-tube or evaporating-basin as long as effervescence occurs, and then evaporate some of the water.* When the solution is cold, crystals of acetate of sodium (NaC 2 H 30 ^, 3 H 20 ) (Sodii Acetas^ U. S. P.) will be depos- ited. A ten per cent, solution in distilled water forms the “ Solution of Acetate of Soda,^^ B. P. JSTa.CO^ + = 2NaC,H30, + H.,0 + CO, Carbonate Acetic Acetate of Water. Carbonic of sodium. acid. sodium. acid gas. Bicarbonate of Sodium. Fourth Synthetical Reaction. — The action of carbonic acid (H 2 CO 3 ), or carbonic acid gas (CO,) and water (H, 0 ), on carbonate of sodium (Na.,C 03 ). This resembles that of carbonic acid on carbonate of potassium, but is applied in a different manner. The result is bicarbonate of sodium (NallCOg) {Sodii Bicarbonas Veiialis^ TJ. P. S.). Na,C03 + lip + CO, = 2NaHC03 Carbonate Water. Carbonic Bicarbonate of sodium. acid gas. of sodium. Process. — Heat crystals of carbonate of sodium in a por- celain crucible until no more steam escapes. Mix the pro- duct, in a mortar, with two-thirds its weight of crystals, and place the powder in a test-tube or small bottle into which carbonic acid gas may be conveyed by a tube pass- ing through a cork and terminating at the bottom of the vessel. To generate the carbonic acid gas fill a test-tube having a small hole in the bottom (or a similar piece of glass tubing, of which one end is plugged b}^ a grooved cork) with fragments of marble, insert a cork and delivery- tube, and connect the latter with the similar tube of the * The “water” alluded to occurs in the acid, which, though com- monly termed “acetic acid,” is really a solution of that acid in water. 70 THE METALLIC RADICALS. vessel containing the carbonate of sodium by a piece of India-rubber tubing. Now plunge the tube of marble into a test-glass, or other vessel, containing a mixture of one part h 3 ^drochloric acid and two parts water, and loosen the cork of the carbonate-of-sodium tube until carbonic acid gas, generated in the marble tube, may be considered to fill the whole arrangement ; then replace the cork tightlj^ and set the apparatus aside. As the gas is absorbed by the carbonate of sodium, h^^drochloric acid rises into the marble tube, generates fresh gas, which, in its turn, drives back the acid liquid, and thus prevents the production of any more gas until further absorption has occurred. When the salt is wholl}^ converted into bicarbonate (NaHCOg), it will be found to have become damp through the libera- tion of water from the crystallized carbonate (Na.^COg, lOH^O). (It would be inconveniently moist, even semi- fluid, if a part of the carbonate had not previously been rendered anh^^drous.) The Sodu Bicarhonas^ U. S. P., is the commercial bicarbonate purified from any carbonate or traces of other salts by introducing it into a percolator and passing water through it till the washings cease to precipi- tate a solution of sulphate of magnesium, the bicarbonate of sodium is then removed from the percolator and dried on bibulous paper in a warm place. A crystal of carbonate of sodium is carbonate of sodium plus water ; on heating it, more or less of the water is evolved, and anhy- drous carbonate of sodium is partially or wholly produced [Sodii Carbonas Exsiccata, U. S. P.). Na2CO3,10H2O — lOH^O = Na^COg Crystallized carbonate Water. Dried carbonate of sodium. of sodium. Note on Nomenclature. — Anhydrous bodies (from a, a, and rScop, liudor, i. e. without water) are compounds from which water has been taken, but whose essential chemical properties are unaltered. Salts containing water are hydrous bodies ; of these the larger portion are crystalline, and their water is then termed water of crystallization. Non-crystalline hydrous compounds were formerly spoken of as hydrated substances ; hydrates are, however, a distinct class of bodies, salts derived from water by one-half of its hydrogen becoming displaced by an equivalent quantity of another radical. Anhydrides arc compounds from which the elements of water have been removed, their essential chemical (acid) properties being thereby greatly altered. (For illustrations, see Index, “Anhydrides.”) Water of Crystallization. — The water in crystallized carbonate of sodium is in the solid condition, and, like ice and other fusible substances, requires heat for its liquefaction. Many salts (freezing- SODIUM. n mixtures), when dissolved in water, give a very cold solution. This is because they and their solid water, if they have any, are then converted into liquids which absorb heat from surrounding media. Take away from water some of its heat, the result is ice. Give to ice (at 32^ F.) more heat than it contains already, the result is water (still at 32^ F.). ( Heat thus taken into a substance without increasing its temperature is said to become latent — from latens, hiding ; it is no longer discoverable by the sense of touch or the thermometer. The term latent gives a somewhat incorrect idea, however, of the process ; for our knowledge of the extent and readiness with which one form of force is convertible into another renders highly probable the assumption that heat is in these cases converted into motion, the latter enabling the particles of a solid to take up the new positions demanded by their liquid condition.) The only apparent difference between ice and the water in such crystals as carbonate of sodium is that ice is solid water in the free, and water of crystallization solid water in the combined state. The former can only exist at and below freezing, the latter at ordinary temperatures. In chemical formulae, the symbols representing water are usually separated by a comma from those representing salts. The crystals of acetate of sodium (of the third reaction) contain water in this loose state of combina- tion — water of crystallization (Na 02 H 302 , 3 H.^ 0 ). “ Soda-watery — A solution of bicarbonate of sodium in water charged with carbonic acid gas under pressure constitutes the official Liquor So dee Effervescens, B. P., and, like the “potash-water’’ of the shops, is a true medicine, an antacid. Ordinary “ soda-water,” how- ever, is in many cases simply a solution of carbonic acid gas in water, and would be more appropriately termed “ aerated water” : any medicinal effect it may possess is clue to the sedative influence of its carbonic acid gas on the coats of the stomach. At common tempera- tures water dissolves about its own volume of carbonic acid gas, both being under equal pressure. One pint of the official soda-water contains 30 grains of bicarbonate of sodium and a pint of carbonic acid gas ; but the solution is under a pressure of seven atmospheres, so that seven pints of the gas at ordinary atmospheric pressure are required for the quantity mentioned. Solubility of Gases in Water. — 'Whatever the weight and volume of a gas dissolved by a liquid at ordinary atmospheric pressure, that weight is doubled by double pressure, the two volumes of gas thereby being reduced to one, trebled at treble pressure, the three volumes of gas being reduced to one, quadrupled at quadruple pressure, the four volumes of gas being reduced to one, and so on. This is a general law regarding the solubility of gases in liquids under given temperatures. An average bottle of “ soda-water” contains about four times the weight of carbonic acid gas which can exist in it without artificial pressure, so that on removing its cork three times its bulk escape, its own bulk remaining dissolved. Bicarbonate of sodium may also be medicinally administered in the form of lozenge {Trochisci Sodii Bicarbonatis^ U. S. P.). 72 THE METALLIC RADICALS. Tartrate of Potasium and Sodium. Fifth Synthetical Reaction, — To some hot strong solu- tion of carbonate of sodium in a test-tube or larger vessel add acid tartrate of potassium till no more effervescence occurs (about three parts to four will be required) ; when the solution is cold, crystals of double tartrate of potas- sium and sodium {Soda Tartar ata,, B. P., Potassii et Sodii Tartras,^ U. S. P.), the old Rochelle Salt,, will be deposited. (KNaC4H^Og,4H^O). The crystals are usually halves of right rhombic prisms. Na,C 03 + 2KIIC,H,Oe = 2KNaC,H,Og -f H,0 + CO, Carbonate Acid tartrate Double tartrate of Water. Carbonic of sodium. of potassium. potassium and sodium. acid gas. Formula: of Tartrates. Tartaric acid HH C^H^Og Acid tartrate of potassium . . . KH C 4 H 40 g Tartrate of potassium and sodium . KNaC^H^Og Very close analogy will be noticed in the constitution of these salts. When the other tartrates come under notice it will be found they also have a similar constitution. Hypochlorite of Sodium. Sixth Synthetical Reaction. — Pass chlorine {vide page 24) into a solution of carbonate of sodium. The result is a bleaching and disinfecting liquid, which, when made of pre- scribed strength (12 ounces of carbonate in 36 of water, charged by the washed chlorine from 15 fluidounces of hydrochloric acid and 4 ounces of black oxide of manga- nese), is the Solution of Chlorinated Soda {Liquor Sodae Chloratae) of the British Pharmacopoeia. It is said to contain chloride of sodium (NaCl) and hypochlorite of sodium (NaClO), with some undecomposed bicarbonate of sodium. MnO, + 4IIC1 = MnCl, -f 2H.,0 + Cl, Blk. oxide of Hydrochloric Chloride of Water. Chlorine, manganese. acid. manganese. Na,CO, + Cl., = NaCI,NaC10 + CO, Carbonate Chlorine. Chlorinated Carbonic of sodium. soda. acid gas. Liquor Sodoc Chlorinatce, U. S. P., is made by decomposing solu- tion of carbonate of sodium by solution of chlorinated lime, sp. gr. 1.045. 2 Na,C 03 + CaCl.,.Ca2C10 = 2(NaClNaC10) -+- 2 CaC 03 Carbonate Chlorinated Chlorinated Carbonate of sodium. lime. soda. of calcium. I SODIUM. 73 other Sodium Compounds. Synthetical Reactions portraying the chemistry of the remaining official compounds (namely, nitrate, sulphate, hyposulphite, borate, arseniate, and valerianate of sodium) are deferred until the several acidulous radicals of these salts have been described. Phosphate of Sodium. — The preparation and composition of this salt will be most usefully studied after bone-ash, the source of it and other phosphates, has been described. Bone-ash is phosphate of cal- cium (see page 94). The official Citro-Tartrate {Sodce Citro-tartras Effervescens^ B. P.) is a mixture of bicarbonate of sodium (17 parts), citric acid (6), and tartaric acid (8), heated (to 200^ or 220*^) until the particles aggregate to a granular condition. When required for medicinal use, a dose of the mixture is placed in water ; escape of carbonic acid gas at once occurs, and an effervescing liquid results. Soda Powders [Pulveres Effervescent es, U. S. P.) are formed of 30 grains of bicarbonate of sodium and 25 of tartaric acid, wrapped separately in papers of different color. When mixed with water, tartrate of sodium results, a little bicarbonate also remaining. In the manufacture of Carbonate of Sodium from chloride, the latter is first converted into sulphate, the sulphate is then roasted with coal and limestone, and the resulting black-ash lixiviated [lixi~ via, from lix, lye — water impregnated with alkaline salts : hence lixiviation, the operation of washing a mixture with the view of dissolving out salts). The lye, evaporated to dryness, yields crude carbonate of sodium (soda-ash). This process will be further de- scribed in connection with Carbonates. Deliquescence and Effiorescence. — The carbonates of sodium and potassium, chemically closely allied, are readily distinguished physi- cally. Carbonate of potassium quickly absorbs moisture from tlie air and becomes damp, wet, and finally fluid — it is deliquescent [deli- quescens, melting away). Carbonate of sodium, on the other hand, yields some of its water of crystallization to the air, the crystals becoming white, opaque, and pulverulent — it is efflorescent [effio- rescens, blowing as a flower). Analogy of Sodium salts to Potassium salts. — Other synthetical reactions might be described similar to those given under potassium, and thus citrate, iodide, bromide, iodate, bromate, chlorate, manga- nate, and permanganate of sodium, and many other salts be formed. But enough has been stated to show how chemically analogous sodium is to potassium. Such analogies will constantly present themselves. In few departments of knowledge are order and method more perceptible; in few is there as 'much natural law, as much science, as in chemistry. Substitution of Potassium and Sodium salts for each other . — Sodium salts being cheaper than potassium salts, the former may sometimes be economically substituted. That one is employed rather Y4 THE METALLIC RADICALS. than the other, is often merely a result due to accident or fashion. But it must be borne in mind that in some cases a potassium salt will crystallize more readily than its sodium analogue, or that a sodium salt is stable when the corresponding potassium salt has a tendency to absorb moisture, or one may be more soluble than the other, or the two may have different medicinal effect. For these or similar reasons, a potassium salt has come to be used in medicine or trade, instead of the corresponding sodium salt, and vice versa. Whenever the acidulous portion only is to be utilized, the least expensive salt of the class would nearly always be selected. (6) Reactions liacing Analytical Interest, 1. The chie f o^naly tic al reaction for sodium is the fiame- test. When brought into contact with a flame in the manner described under potassium (page 66), an intensely yellow color is communicated to the flame by any salt of sodium. This is highly cliaracteristic — indeed, almost too delicate a test ; for if the point of the wire be touched by the fingers, enough salt (wdiich is contained in the moisture of the hand) adheres to the wire to communicate a very distinct sodium reaction. These statements should be ex- perimentally verified, the chloride, sulphate, or any other salt of sodium being emploj^ed. 2. Precipitant of Sodium . — Sodium is the only metal whose com- mon salts are all soluble in water. Hence no ordinary reagent can be added to a solution containing a sodium salt which shall give a precipitate containing the sodium. A neutral or alkaline solution of a sodium salt gives, however, a granular precipitate of antimoniate of sodium (Na-^H.^Sb^O-, 6H2O) if well stirred or shaken with a solu- tion of antimoniate of potassium (K2H2Sb207), but the reagent precipitates other metals, and is liable to decompose and become useless, and hence is seldom employed. Antimoniate of potassium is made by adding, gradually, finely powdered metallic antimony to nitrate of potassium fused in a cruci- ble so long as deflagration continues. The resulting mass is boiled with a large quantity of water, the solution filtered and preserved in a well-stoppered bottle ; for the carbonic gas in the air is rapidly absorbed by the solution, antimonic acid being deposited. 3. Sodium salts, like those of potassium, are not volatile. Prove this fact by the means described when treating of the effect of heat on potassium salts (p. 66). AMMONIUM. 75 QUESTIONS AND EXERCISES. 98. How is the official solution of soda prepared ? Give a dia- gram or equation. 99. Explain the action of sodium or potassium on water. What colors do these elements respectively communicate to flame ? 100. How much bicarbonate of sodium can be obtained from 2240 pounds of crystallized carbonate of sodium ? Ans. 1316 lbs. 101. Acetate of sodium: give formula, process, and equation. 102. Give a diagram showing the formation of bicarbonate of sodium. 103. Why is a mixture of dried and undried carbonate of sodium employed in the preparation of the bicarbonate ? 104. State the difference between anhydrous and crystallized car- bonate of sodium. 105. Define the terms anhydrous, hydrous, hydrate, anhydride. 106. What do you understand by ivater of crystallization ? 107. What is the nature of “ Soda-water ?” 108. How many volumes of gas (reckoned as at ordinary atmo- spheric pressure) are contained in any given volume of the British official “ Soda-water ?” 109. What is the general law regarding the solubility of gases in liquids under pressure ? 110. What is the systematic name of Rochelle salt, and how is the salt prepared ? 111. What is the relation of Rochelle salt to cream of tartar and tartaric acid ? 112. Give the mode of preparation and composition of solution of chlorinated soda, and express the process by a diagram. 113. How is the granular effervescing Citro-tartrate of Sodium prepared ? 114. Define Deliquescence, Efflorescence, and Lixiviation. 115. What is the general relation of potassium salts to those of sodium ? 116. How are sodium salts analytically distinguished from those of potassium ? AMMONIUM. Symbol NH^ or Am. Atomic weight 18. ✓ Memoranda . — The elements nitrogen and hydrogen, in the pro- portion of one atom to four (NH^), are those characteristics of all the compounds about to be studied, just as potassium (K) and sodium (Na) are the characteristic elements of the potassium and sodium compounds. Ammonium is a univalent nucleus, root, or radical, like potassium or sodium ; and the ammonium compounds closely resemble those of potassium or sodium. In short, if, for an instant, potassium or sodium be imagined to be compounds, the analogy between these 76 THE METALLIC RADICALS. three series of salts is complete. Yet ammonium never having been isolated, its existence remains a matter of assumption. Source. — The source of nearly all the ammoniacal salts met with in commerce is ammonia-gas (NH^) obtained in distilling coals in the manufacture of ordinary illuminating gas. It is doubtless derived from the nitrogen of the plants from which the coal has been pro- duced. Ammonia. — When this gas (NHg) comes into contact with water (H 2 O), in the process of washing and cooling coal-gas, hydrate of ammonium (NH^HO, or AmHO) is believed to be formed, the analogue of hydrate of potassium (KHO) or sodium (NaHO). The grounds for this belief are the observed analogy of the well-known ammoniacal salts to those of potassium and sodium, the similarity of action of solution of potash, soda, and ammonia on salts of most metals, and the existence of crystals of an analogous sulphur salt (NH.HS). Chloride of Ammonium. — The “ ammoniacal liquor” of the gas- works is usually neutralized by hydrochloric acid, by which chloride of ammonium (sal-ammoniac) is produced. NH,HO + HCl = NH,C1 + H^O ; and from this salt, purified, the others used in pharm’acy are directly or indirectly made. Chloride of ammonium [Ammonii Chloridum, B. P. and U. S. P.) occurs “ in colorless, inodorous, translucent fibrous masses, tough, and difficult to powder, soluble in water [1 in 10 is the ‘ Solution of Chloride of Ammonium,’ B. P.] and in rectified spirit.” Chloride of ammonium generally contains slight traces of oxychloride of iron, tarry matter, and possibly chlorides of compound ammoniums {vide “ Artificial Alkaloids” in Index). Sidphate of Ammonium (NH 4 ) 2 , SO^, results when “ammoniacal liquor” is neutralized by oil of vitriol. It is largely used as a con- stituent of artificial manure in England, and when purified by recrys- tallization is employed in pharmacy (Ammonii Sidplias, U S. P.). Volcanic Ammonia. — The purest form of ammonia is that met with in volcanic districts, and obtained as a by-product in the manufacture of borax ; the crude boracic acid as imported contains about 10 per cent, of ammonium salts, chiefly sulphate, and double sulphates of ammonium with magnesium, sodium, and manganese (Howard). Reactions haying {a) General (5) Synthetical, and (c) Analytical Interest. Ammomiuin-Amalgam. (?) (a) General Reaction , — To forty or fifty grains of dry rnerciiry in a di'y test-tube, add one or two small'pieces of sodium (freed from adhering naphtha by gentle pressure with a piece of filter-paper), and amalgamate by gently warming the tube. To this amalgam, when cold, add some fragments of chloride of ammonium and a strong solution^ AMMONIUM. 11 of the same salt. The sodium amalgam soon begins to swell and rapidly increase in bulk, probablj^ overflowing the tube. The light spongy mass produced is the so-called ammonium-amalgam, and the reaction is usually adduced as evidence of the existence of ammonium; the sodium of the amalgam unites with the chlorine of the chloride of am- monium, while the ammonium is supposed to form an amalgam with the mercury. As soon as formed the amal- gam gives off hydrogen and ammonia gases ; this decom- position is complete after some minutes, and a globule of mercury alone remains. (b) Reactions having Synthetical Interest. Hydrate of Ammonium. Ammonia. First Synthetical Reaction , — Heat a few grains of sal- ammoniac with about an equal weight of hydrate of calcium (slaked lime) damped with a little water in a test-tube; ammonia gas is given off, and may be recognized by its well-known odor. It is very soluble in water. Pass a delivery-tube, fitted to the test-tube as described for the preparation of oxygen and hydrogen, into a second test- tube, at the bottom of which is a little water; again heat; solution of ammonia will be thus formed. 2NH^C1 + Ca2HO = CaCl, -f + 2NH3 Chloride of Hydrate of Chloride of Water, Ammonia ammonium. calcium. calcium. gas. Ammonia gas is composed of one atom of nitrogen with three atoms of hydrogen; its formula is NHg; two volumes of it contain one volume of nitrogen combined with three atoms or volumes of hydrogen. Its constituents have therefore in combining suffered con- densation to one-half their normal bulk. Its conversion into hydrate of ammonium may be thus shown : — NH 3 + H,0 = NH,HO or AmHO Ammonia Water. Hydrate of ammonium gas. (ammonia). Solutions of Ammonia, prepared by this process on a large scale and in suitable apparatus, are met with in pharmacy — the one (sp. gr. 0.891) containing 32.5 per cent., the other (sp. gr. 0.959), 10 per cent., by weight, of ammonia gas, NH 3 , or 66.9 and 20.6 of ammonia, NH^HO ifLiquor Ammonioe Fortior and Liquor Ammonice, B. P. One part, by measure, of the former, and two of water form the latter). On the large scale, bottles are so arranged in a series as to condense all the ammonia evolved during the operation. Aqua Ammonioe Fortior, U. S. P., sp. gr. 0.900, contains 26 per cent, of ^ ammonia gas. Aqua Ammonioe, U. S. P., has a sp. gr. of 0.960. I* THE METALLIC RADICALS. 78 Note. — When water is mixed with strong solution of ammonia, ex- pansion occurs. Thus, calculating from the stated specific gravities of the official solutions, 3000 parts by measure of the Liquor Am- monice weigh 2877 parts (959 X 3) ; whereas 1000 parts by measure of the Liquor Ammonice Fortior (weighing 891 parts) and 2000 measures of water (weighing 2000) weigh 2891 parts. Apparently 1000 volumes of the strong solution of ammonia with 2000 volumes of water yield 3000 volumes of mixture, and 14 parts by weight, or 15 volumes to spare, total 3015 volumes — an expansion of about half of one (.5) per cent. Acetate of Ammonium. Second Synthetical Reaction . — To acetic acid and water in a test-tube add })owdered commercial carbonate (acid carbonate and carbamate) of ammonium until effervescence ceases ; the resulting* liquid, made of prescribed strength, is the official solution of Acetate of Ammonium (NH^C2H302) {Liquor Ammonii Acetatis., U. S. P.). (NH.HCO^O^NH.NII^CO^ + Acid carbonate and carbamate Acetic acid. Acetate of of ammonium. ammonium. + 2H.,0 + SCO, Water. Carbonic acid gas. Carbonates of Ammonium. Commercial carbonate of ammonium is made by heating a mix- ture of chalk and sal-ammoniac; chloride of calcium (CaC^) is pro-, duced, ammonia gas (NH3) and water (H2O) escape, and the ammo- niacal carbonate distils, or rather sublimes,* in cakes [Ammonii Carbonas, B. P. and U. S. P.). The best form of apparatus to em- ploy is a retort with a short wide neck and a cool receiver. On the large scale the retort is usually iron and the receiver earthenware or glass ; on the small scale glass vessels are employed. The salt is purified by resublimation at a low temperature ; 150^ F. is said to be sufficient. This salt, the empirical formula of which is N^H^gCgOg, is probably a mixture of two molecules of acid carbonate or bicarbonate of am- moniuih (2NH^HC03) and one of a salt termed carbamate of ammo- nium (NH^NH2C02). The latter belongs to an important class of salts known as carbamates, but it is the only one of interest to the pharmacist. Cold water extracts it from the commercial carbonate of ammonium, leaving the acid carbonate of ammonium undissolved, if the amount of liquid used be very small. In water carbamate soon changes into neutral carbonate of ammonium, Nn,NH2C02 + II 2 O = (NHj 2 C 03 or Am 2 C 03 ; * Sublimation (from suhlimis^ high). Vaporization of a solid sub- stance by heat, and its condensation on an upper and cooler part of the vessel or apparatus in which the operation is performed. AMMONIUM. 19 SO that an aqueous solution of commercial carbonate of ammonium contains both acid carbonate and neutral carbonate of ammonium. If to such a solution some ordinary solution of ammonia be added, a solution of neutral carbonate of ammonium is obtained ; and this is the common reagent always found on the shelves of the analytical laboratory. AmllCOg 4 - AmHO = Am.COg + H, 0 . Neutral carbonate of ammonium is the salt formed on adding strong solution of ammonia to the commercial carbonate in preparing a pungent mixture for toilet smelling-bottles ; but it is unstable, and on continued exposure to air is reduced to a mass of crystals of the acid carbonate or bicarbonate of ammonium. Bicarbonate of am- monium (NH4HCO3) is also produced on passing carbonic acid gas into an aqueous solution of commercial carbonate. According to Divers, the sublimed product of the first distillation of chalk and sal-ammoniac is a mixture of carbamate and carbonate of ammonium, the latter losing some ammonia gas on redistillation, and carbamate with bicarbonate forming the resulting commercial salt. Dr. Divers considers that the salt now met with in trade con- tains one molecule of acid carbonate to one of carbamate, and not two of the former to one of the latter, as was the case when the ana- lyses were made from which the foregoing formulae were deduced. Sal Volatile {Spiritus Ammonice Aromaticus, B.P. and U. S.P.) is a spirituous solution of ammonia (AmHO), neutral carbonate of ammonium (Am^COg), and the oils of nutmeg and lemon (and laven- der, U. S. P.). Fetid spirit of ammonia [Spiritus Ammonice Foeti- dus, B. P.) is an alcoholic solution of the volatile oil of assafoetida mixed with solution of ammonia. “ Solution of Carbonate of Am- monia,” B. P., is formed by dissolving half an ounce of the salt in ten ounces of water. Spiritus Ammonice, U. S. P., is an alcoholic solution of ammonia. Citrate, Phosphate, and Benzoate of Ammonium. Third Synthetical Reaction . — To solution of citric acid (HgCjjH.Oy or HgCi) add solution of ammonia (AmHO) until the liquid is neutral to test-paper ; the product is So- lution of Citrate of Animonium (AmgCi) Liquor Ammonise Citratis.^ B. P.). Phosphate of Ammonium (Am2HP04) [Ammonice, Phosphas, B. P.) and Benzoate of Ammonium (AmC7H302) [Ammonii Ben- zoas, U. S. P.) are also made by adding solution of ammonia to phosphoric acid (H3PO4) and benzoic acid (HO7H-O2) respectively, evaporating (keeping the ammonia in slight excess by adding more of its solution), and setting aside for crystals to form. The official Solution of Acetate of Ammonium could be made in the same way ; but, when prepared with Carbonate of Ammonium, the liquid re- mains charged with carbonic acid, and has a less vapid flavor. 80 THE METALLIC RADICALS. H3CAO, Citric acid. + SAmllO Ammonia. Citrate of ammonium. 3IT2O Water. H3P0, Phosphoric acid. + 2 AmHO Ammonia. = Am2HP04 Phosphate of ammonium. + 2H2O Water. H0,H50, Benzoic acid. + AmHO Ammonia. = AmC^H^O.^ Benzoate of ammonium. + H2O Water. Phospliate of ammonium occurs in transparent colorless prisms, solu- ble in water, insoluble in spirit ; benzoate in crystalline plates, solu- ble in water and in spirit. Ammonii lodidum^ U. S. P., is made by decomposing the two bodies iodide of potassium and sulphate of ammonium, which give iodide of ammonium and sulphate of potassium ; the latter salt is separated by adding alcohol to the cooled solution, when, by reason of its insolubility in alcohol, it crystallizes out, and the separated solution of iodide of ammonium is then evaporated to dryness. Bromide of Ammonium [Ammonii Bromidum, B. P. and U. S P.) will be noticed in connection with Hydrobromic Acid and Other Bromides. Oxalate of Ammonium. Fourth Synthetical Reaction . — To a nearly^ boiling solu- tion of 1 part of oxalic acid in about 8 of water add carbonate of ammonium until the liquid is neutral tt) test-paper, filter while hot, and set aside for crystals (NH^)2C20^,H20) to form. The mother-liquor is useful as a reagent in analysis : 1 of the salt in 40 of water consti- tutes “Solution of Oxalate of Ammonia,’’ B. P. 2H,C,0, + N,H,,C303 = 2(NH,),C,0, + SCO, + 2H,0 Oxalic Carbonate of Oxalate of Carbonic Water, acid. ammonium. ammonium. acid gas. Sulphydrate of Ammonium. Fifth Synthetical Reaction . — Pass sulphuretted hydro- gen gas (H 2 S) through a small quantity of solution of am- monia in a test-tube, until a portion of the liquid no longer causes a white precipitate in solution of sulphate of mag- nesium (Epsom salt) ; the product is solution of sulphy- drate (or sulphide) of ammonium (NH^HS), the “ Solution of Sulphide of Ammonium” of the British Pharmacopoeia, a most valuable chemical reagent, as will presently be a !> parent. NHJIO + n^S = Nil, IIS -f H^O. SULPHURETTED HYDROGEN. 81 Solution of Sulphide of Ammonium f B. P., is made by passing tlie gas prepared in the apparatus described below into 3 fluidounces of solution of ammonia [Liquor Ammonice) so long as the gas continues to be absorbed, then adding 2 more ounces of solution of ammonia, and preserving the solution in a well-stoppered bottle. Sulphuretted hydrogen is a compound of noxious odor ; hence the above operation, and many others, described further on, in which this gas is indispensable, can only be performed in the open air, or in a fume-cupboard, a chamber so contrived that deleterious gases and vapors shall escape into a chimney in connection with the external air. In the above experiment, the small quantity of gas required can be made in a test-tube, after the manner of hydrogen itself. To two or three fragments of sulphide of iron (FeS),add water and then sulphuric acid ; the gas is at once evolved, and may be conducted by a tube into the solution of ammonia. FeS + H,SO, = H,S + FeSO,. The iron remains dissolved in the water in the state of sulphate of iron. Crystals of sulpliy dr ate of ammonium (NH^HS) may be obtained on bringing ammonia gas (NH 3 ) and sulphuretted hydrogen (H 2 S) together at a low temperature. They are soluble in water without decomposition. Sulphuretted-hydrogen Apparatus , — As no heat is neces- sary in making sulphuretted hydrogen, the test-tube of the foregoing operation may be advantageously replaced by a bottle, especially when larger quantities of the gas are required. In anal3Tical operations, the gas should be purified by passing it through water contained in a second bottle. The most convenient arrangement for experimental use is prepared as follows: Two common wide-mouth bottles are selected, the one having a capacity of about half a pint, the other a quarter pint; the former ma}^ be called the generating-bottle, the latter the wash-bottle. Fit two corks to the bottles. Through each cork bore two holes hy a round file or other instrument, of such a size that glass tubing of about the diameter of a quill pen shall fit them tightly. Through one of the holes in the cork of the generating- bottle pass a funnel-tube, so that its extremity may nearly reach the bottom of the bottle. Such “funnel-tubes’’ may^ be purchased at the usual shops ; or, if the student has access to a table-blowpq)e, and the advantage of a tutor to 82 THE METALLIC RADICALS. direct his operations, they may be made by himself. To the other hole adapt a piece of tubing, 6 inches long, and bent in the middle to a right angle. A similar “ elbow- tube’’ is fitted to one of the holes in the cork of the wash- bottle, and another elbow-tube, one arm of which is long enough to reach to near the bottom of the wash-bottle, fitted to the other hole. Removing the corks, two or three ounces of water are now poured into each bottle, an ounce or two of sulphide of iron put into the generating- bottle, and the corks replaced. The elbow-tube of the generating-bottle is now attached hy a short piece of India-rubber tubing to the long-armed elboAv-tube of the wash-bottle, so that gas coming from the generator may pass through the water in the wash-bottle. The delivery- tube of the wash-bottle is then lengthened by attaching to it, by India-rubber tubing, a straight piece of glass tubing, three or four inches long. The apparatus is now ready for use. Strong sulphuric acid is poured down the funnel-tube in small quantities at a time, until brisk effervescence is established, and more added from time to time as the evolution of gas becomes slow. The gas passes through the tubes into the wash-bottle, where, as it bubbles up through the water, an}^ trace of sulphuric acid, or other matter mechanically carried over, is arrested, and thence flows out at the deliver 3 '-tube into any vessel or liquid that may be placed there to receive it. The generator must be occasionally dismounted, and the sulphate of iron washed out. Luting [lutum, mud). — If the corks of the above apparatus are sound, and tube-holes well made, no escape of gas Avill occur. If rough corks have been employed, or the holes are not cylindrical, linseed-meal lute may be rubbed oA^er the defective parts. The lute is prepared by mixing linseed-meal Avith Avater to the consistence of dough. A neat appearance may be given to the lute by gently rub- bing a well-wetted finger over its surface. (c) Reactions having Analytical Interest {Tests,) First Analytical Reaction . — To a solution of any salt of ammonium (the chloride, for example) in a test-tube add solution of caustic soda (or solution of potash, or a little slaked lime) ; ammonia gas is at once evolved, recognized by its well-knoAvn odor. NII^CT + NallO = NII 3 + 11,0 + NaCl. SULPHURETTED HYDROGEN. 83 Though ammonium itself cannot exist in the free state, its com- pounds are stable. Ammonia is easily expelled from those compounds by action of the stronger alkalies, caustic potash, soda, or lime. As a matter of exercise, the student should here draw out equations in which acetate {NH^C 2 H 302 ), sulphate (Am 2 S 04 ), nitrate (NH^NOj) or any other ammoniacal salt not already having the odor of am- monia, is supposed to be under examination ; also representing the use of the other hydrates, potash (KHO) or slaked lime (Ca2HO). The odor of ammonia gas is perhaps the best means of recognizing its presence ; but the following tests are also occasionally useful. Into the test-tube in which the am- monia gas is evolved insert a glass rod moistened with hydrochloric acid (that is, with the solution of hydro- chloric acid gas, conveniently termed hydrochloric acid, the Acidam Hydrochloricum of the Pharmacopseias) ; white fumes of chloride of ammonium will be produced. NH 3 -f HCl = NH,C1. Hold a piece of moistened red litmus paper in a tube in which ammonia gas is present; the red color will be changed to blue. Test-papers. — Litmus (B. P.) is a blue vegetable pigment, pre- pared from various species of Roccella lichen, exceedingly sensitive to the action of acids, which turn it red. When thus reddened, alka- lies (potash, soda, and ammonia) and other soluble hydrates readily turn it blue. The student should here test for himself the delicacy of this action by experiments with paper soaked in solutions of litmus and dipped into very dilute solutions of acids, acid salts (KHC^H^Og e.g.), alkalies, and such neutral salts as nitrate of potassium, sul- phate of sodium, or chloride of ammonium. Tincture of Litmus. — 1 ounce of litmus is macerated for two days in 10 fluidounces of proof spirit, and the solution poured off from in- soluble matter. Blue litmus paper is unsized white paper steeped in tincture of litmus and dried by exposure to the air. Red litmus paper is unsized white paper steeped in tincture of litmus which has been previously reddened by the addition of a very minute quantity of sulphuric acid, and dried by exposure to the air. Turmeric paper, similarly prepared from tincture of turmeric (1 of turmeric root or rhizome to 6 of rectified spirit, macerated for seven days), is occasionally useful as a test for alkalies, which turn its yellow to brown ; acids do not affect it. Second Analytical Reaction . — To a few drops of a solu- tion of an ammonium salt add a drop or two of hydrochloric acid and a like small quantity of solution of perchloride of platinum (PtClJ ; a yellow crystalline precipitate of the double chloride of platinum and ammonium (PtC1^2NH^Cl) 84 THE METALLIC RADICALS. will be produced, similar in appearance to the corresponding salt of potassium, the remarks concerning which (p. 65) are equally applicable to the precipitate under notice. Third Analytical Reaction , — To a moderately strong solution of an ammonium salt add a strong solution of tartaric acid, and shake or well stir the mixture ; a white granular precipitate of acid tartrate of ammonium will be formed. For data from which to draw out an equation representing this action, see the remarks and formulae under the analogous salt of potassium (p. 65). Fourth Analytical Fact , — Evaporate a few drops of a solution of an ammonium salt to dryness, or place a frag- ment of a salt in the solid state on a piece of platinum foil, and heat in a flame ; the salt is volatilized. As already noticed, the salts of potassium and sodium are fixed under these circumstances, a point of difference of which advantage wdll frequently be taken in analysis. A porcelain crucible may often be advantageously substituted for platinum foil in experiments on volatilization. A wire-triangle may be used in supporting crucibles. It is made by placing three (5 or 6 inch) pieces of wire in the form of a triangle and then twisting each pair of ends together through half the length of the wires. A piece of tobacco-pipe stem (about 2 inches) is some- times placed in the centre of each wire before twisting, the transfer- ence of any metallic matter to the sides of the crucible being thus prevented. Practical Analysis, With regard to those experiments which are useful rather as means of detecting the presence of potassium, sodium, and ammonium, than as illustrating the preparation of salts, the student should proceed to apply them to certain solutions of any of the salts of potassium, sodium, and ammonium, with the view of ascertaining which metal is present ; that is, proceed to practical analysis.* A little thought * Such solutions are prepared in educational laboratories by a tutor. They should, under other circumstances, be mixed by a friend, as it is not desirable to know previously what is contained in the substance about to be analyzed. The analysis of solutions containing only one salt serves to impress the memory with the characteristic tests for the various metals and other radicals, and familiarize the mind with chemical principles. Medical students seldom have time to go further than this. More thorough analytical and general chemical knowledge is only acquired POTASSIUM, SOUIUxM, AMMONIUM. S5 will enable him to apply these reactions in the most suitable order and to the best advantage for the contemplated purpose ; but the following arrangements are perhaps as good as can be devised: — DIRECTIONS FOR APPLYING THE FOREGOING ANALYTICAL RE- ACIONS TO THE ANALYSIS OF AN AQUEOUS SOLUTION OF A SALT OF OTsTE OF THE METALS, POTASSIUM, SODIUM, Ammonium. Add caustic soda to a small portion of the solution to be examined, and warm the mixture in a test-tube ; the odor of ammonia gas at once reveals the presence of an ammonium salt. If ammonium be not present, apply the perchloride-of- platinum test ; a yellow precipitate proves the presence of potassium. (It will be observed that potassium can only be detected in the absence of ammonium, salts of the latter radical giving similar precipitates.) The flame-test is sufficient for the recognition of sodium. DIRECTIONS FOR APPLYING THE FOREGOING ANALYTICAL RE- ACTIONS TO THE ANALYSIS OF AN AQUEOUS SOLUTION OF SALTS OF OTsTE, TWO, OH ALL THBEE OF THE ALKALI METALS. Commence by testing a small portion of the solution for an ammonium salt. If present, make a memorandum to that effect, and then proceed to get rid of the ammoniacal compound to make way for the detection of potassium: advantage is here taken of the volatility of ammonium salts and the fixity of those of potassium and sodium. Evaporate the original solution to dryness in a small basin, transfer the solid residue to a porcelain crucible, and heat the latter to a low redness, or until dense white fumes (of ammoniacal salts) cease to escape. This opera- tion should be conducted in a fume-cupboard, to avoid contamination of the air of the apartment. When the cru- by working on such mixtures of bodies as are met with in actual practice, beginning with solutions which may contain any or all the members of a group. Hence in this manual, two Tables of short directions for analyzing are given under each group. Pharmaceutical students should follow the second Table. 8 86 THE METALLIC RADICALS. cible is cold, dissolve out the solid residue with a small quantity of hot water, and test the solution for potassium by the perchloride-of-platinum test, and for sodium by the flame test. If ammonium is proved to be absent, the original solu- tion may, of course, be at once tested for potassium and sodium. Flame-test . — The violet tint imparted to flame by potassium salts may be seen when masked by the intense yellow color due to sodium, if the flame be observed through a piece of dark-blue glass, a medium which absorbs the yellow rays of light. Note on Nomenclature. — The operations of evaporation and heating to redness, or ignition, are frequently necessary in analysis, and are usually conducted in the above manner. If vegetable or animal matter be also present, carbon is set free, and ignition is ac- companied by carbonization ; the material is said to char. When all carbonaceous matter is burnt off, the crucible being slightly in- clined and its cover removed to facilitate combustion, and mineral matter, or ash, alone remains, the operation of incmeration has been effected. Note on the Classification of Elements. — The compounds of po- tassium, sodium, and ammonium have many analogies. Their car- bonates, phosphates, and most other salts are soluble in water. The atoms of the radicals themselves are univalent — that is, displace or are displaced by one atom of hydrogen. In fact, they constitute by their similarity in properties a distinct group or family. All the elements thus naturally fall into classes — a fact that should con- stantly be borne in mind, and evidence of which should always be sought. It would be impossible for the memory to retain the details of chemistry without a system of classification and leading princi- ples. Classification is also an important feature in the art as well as in the science of chemistry ; for without it practical analysis could not be undertaken. The classification adopted in this volume is founded, as far as possible, on the quantivalence of the elements, but chiefly on their analytical relations. QUESTIONS AND EXERCISES. 117. Why are ammoniacal salts classed with those of potassium and sodium ? 118. Mention the sources of the ammonium salts. 119. Describe the appearance and other characters of Chloride of Ammonium. 120. (live the formula of Sulphate of Ammonium. 121. Adduce evidence of the existence of ammonium. BARIUM. 87 122. How are the official Solutions of Ammonia prepared ? Hive diagrams. 123. How is the official Solution of Acetate of Ammonium pre pared ? 124. What is the composition of commercial Carbonate of Ammo- nium ? 125. Define suhlimation. 126. What ammoniacal salts are contained in Spmtus Ammontoe Aromaticus ? 127. Give diagrams or equations illustrating the formation of Citrate, Phosphate, and Benzoate of Ammonium. 128. Give the formula of Oxalate of Ammonium. 129. Show how hydrate of ammonium may be converted into sul- phydrate. 130. Describe the preparation of Sulphuretted Hydrogen gas. 131. Enumerate and explain the tests for ammonium. 132. How is potassium detected in a solution in which ammonium has been found ? 133. Give equations illustrating the action of hydrate of sodium on acetate of ammonium ; hydrate of potassium on sulphate of ammo- nium ; and hydrate of calcium on nitrate of ammonium. 134. What are the effects of acids and alkalies on litmus and tur- meric ? 135. Describe the analysis of an aqueous liquid containing salts of potassium, sodium, and ammonium. 136. What meanings are commonly assigned to the terms evapo- ration, ignition, carbonization, and incineration ? 137. Write a short article descriptive of the analogies of potas- sium, sodium, and ammonium, and their compounds. BARIUM, CALCIUM, MAGNESIUM. These three elements have many analogies. Their atoms are bivalent. BARIUM. Symbol Ba. Atomic weight 137. The analytical reactions only of this metal are of interest to the general student of pharmacy. The chloride (BaCl 2 ) (Chloride of Barium, B. P. and IJ. S. P., and “ Solution of Chloride of Barium,” 1 in 10 of water, B. P.) and nitrate (Ba 2 N 03 ) are the soluble salts in common use in analysis ; and these and others are made by dis- solving the native carbonate (BaCOg), Barii Carbonas, U. S. P., the mineral witherite, in acids, or by heating the other common natu- ral compound of barium, the sulphate, heavy ivhite or heavy spOrV (BaSO^), with coal — BaSO, + C 4 = 4CO + BaS, 88 THE xMETALLIC RADICALS. and dissolving the resulting snlpliide in acids. When the nitrate is strongly heated, it is decomposed, the oxide of barium or baryta (BaO) remaining. Baryta, on being moistened, assimilates the ele- ments of water with great avidity, and yields hydrate of barium, (Ba2HO). The latter is tolerably soluble, giving baryta-water; and from this solution crystals of hydrate of barium are obtained on evaporation. The operations above described may all be performed in test-tubes and small porcelain crucibles heated by the gas-flame. Quantities of 1 oz. to 1 lb. require a coke-furnace. Peroxide of barium (BaO.^) is formed on passing air over heated baryta. By the action of dilute hydrochloric acid it yields solution peroxide of hydrogen (H^, 02 ) or oxygenated water. Quantivaleyice. — The atom of barium is bivalent, Ba". Reactions having Analytical Interest (Tests). First Analytical Reaction. — To the solution of any soluble salt of barium (nitrate or chloride, for example) add dilute sulphuric acid ; a white precipitate is obtained. Set the test-tube aside for two or three minutes, and when some of the precipitate has fallen to the bottom pour away most of the supernatant liquid, add strong nitric acid, and boil ; the precipitate is insoluble. The production of a white precipitate by sulphuric acid, insoluble even in hot nitric acid, is highly characteristic of barium. The name of this precipitate is sulphate of barium ; its formula is BaSO^. Antidotes. — In cases of poisoning by soluble barium salts, any sulphates, such as those of magnesium and sodium (Epsom salt, Glauber’s salt, alum), would be obvious antidotes. Second Analytical Reaction. — To a barium solution add solution of the j^ellow chromate of potassium (KfirO^)] a pale yellow precipitate (BaCrOJ falls. Add acetic acid to a portion of the chromate of barium ; it is insoluble. Add hydrochloric or nitric acid to another portion ; it is soluble. “ Neutral Chromate.^’ — The red chromate (or bichromate) of po- tassium (K.^CrO^. CrOg) must not be used in this reaction, or the barium will be only imperfectly precipitated ; for the red salt gives rise to the formation of free acid, in which chromate of barium is to some extent soluble : — K^CrO^, Cr 03 .+ 2 BaCl 2 + II^O = 2BaCrO, + 2KC1 + 2I1C1. Yellow chromate is obtained on adding carbonate of potassium, in small quantities at a time, to a hot solution of the red chromate until eflervescence ceases ; a little more red chromate is then added to insure decomposition of any slight excess of carbonate of potas- sium. KgCrO,, CrOg + K2CO3 = 2K2CrO, 4- CO^, BARIUM. 89 For analytical purposes solution of a neutral chromate is still more readily prepared by simply adding solution of ammonia to solu- tion of red chromate of potassium, until the liquid turns yellow, and, after stirring, smells of ammonia. K^CrO,, Cr 03 + 2NH,HO = 2KNH,CrO, + H,0. Other Analytical Beactions . — To a barium solution add a soluble carbonate (carbonate of ammonium (Am^COg) will generally be rather more useful than others) ; a white precipitate of carbonate of barium (BaCOg) results. To more of the solution add an alkaline phosphate or arseni- ate (phosphate of sodium (Na^HPOJ is the most common of these chemically analogous salts, but phosphate of am- monium (Am.^HPOJ or arseniate (Am2HAsOj will subse- quently have the preference) ; white phosphate of barium (BaHPOJ, insoluble in pure water but slightly soluble in aqueous solutions of some salts, or arseniate of barium (BallAsO^), both soluble even in acetic and other weak acids, are precipitated. To another portion add oxa- late of ammonium (Am5^C20J ; white oxalate of barium (BaC20J is precipitated, soluble in strong acids, and spar- ingly so in acetic acid. The silico-fluoride of barium (BaSiPg) is insoluble, and falls readily if an equal volume of spirit of wine be added to the solution under examina- tion after the addition of hydrofluosilicic acid (H^SiFg.) Barium salts, moistened with hydrochloric acid, impart a greenish color to flame. Mem . — Good practice will be found in writing out equations de- scriptive of each of the foregoing reactions. QUESTIONS AND EXEKOISES. 138. What is the quantivalence of barium ? 139. Write down the formulae of oxide, hydrate, chloride, nitrate, carbonate, and sulphate of barium ; and state how these salts are prepared. 140. Describe the preparation of peroxide of hydrogen. 141. Which of the tests for barium are most characteristic ? Give an equation of the reactions. 142. Name the antidote in cases of poisoning by soluble barium salts, and explain its action. 8 * 90 THE METALLIC RADICALS. CALCIUM. Symbol Ca. Atomic weight 40. Calcium compounds form a large proportion of the crust of our earth. Carbonate of calcium is met with as chalk, marble, lime- stone, calc-spar, etc., the sulphate, as gypsum or plaster of Paris (“ Plaster of Paris, native sulphate of calcium — CaS 04 , 2 H 2 O — deprived of water by heat.” — B. P.), and alabaster, the silicate in many minerals, the fluoride of calcium as fluor-spar. The phosphate is also a common mineral. The element itself is only isolated with great difficulty. The atom of calcium is bivalent, Ca". Reactions having Synthetical Interest. Chloride of Calcium. First Synthetical Reaction , — To some hydrochloric acid add carbonate of calcium (chalk, or, the purer form, white marble. Mariner Album,, B. P. and IT. S. P.) (CaCOg) until effervescence ceases, filter; solution of chloride of calcium (CaCl^), the most common soluble salt of calcium, is formed. CaCOg + 2HC1 = CaCl^ + H^O + CO^ Carbonate of Hydrochloric Chloride of Water. Carbonic calcium. acid. calcium. acid gas. This solution contains carbonic acid, and will give a precipitate of carbonate of calcium on the addition of lime-water. It may be obtained quite neutral by well boiling before filtering off the excess of marble. It is a serviceable test-liquid in analytical operations. Solution of chloride of calcium evaporated to a syrupy consistence readily yields crystals. These are extremely deliquescent. The solu- tion, evaporated to dryness, and the white residue strongly heated, gives solid anhydrous chloride of calcium in a porous form. The resulting agglutinated lumps ( Calcii Chloridum, B. P. and U. S. P.) are much used for drying gases, and for freezing certain liquids from water. The salt is soluble in alcohol. One part in ten of water constitutes a useful test-liquid, “ Solution of Chloride of Calcium,” B. P. Four parts in five of water forms the “ Solution (saturated) of Chloride of Calcium,” B. P. Marble often contains ferrous carbonate (FeC02), in the above pirocess becomes converted into ferrous chloride, rendering the chloride of calcium impure : — FeCOg -f 2nCl = FeCl^ + H,0 + CO^ Ferrous Hydrochloric Ferrous Water. Carbonic carbonate. acid. chloride. acid gas. If absolutely pure chloride of calcium be required, a few drops of the solution should be poured into a test-tube or CALCIUM. 91 test-glass, diluted with water, and examined for iron (by adding sulphydrate of ammonium, which gives a black precipitate with salts of iron), and, if the latter is present, hypochlorite of calcium (in the form of chlorinated lime) and slaked lime should be added to the remaining bulk of the liquid, and the whole boiled for a few minutes, wliereby iron (as ferric hydrate) is thus precipitated ; on filtering, a pure solution of chloride of calcium is obtained: — Ferrous chloride. + Ca2C10 + 4CaH.p, + Hypochlorite Hydrate of of calcium. calcium. = 2(Fe,6HO) Fen-io hydrate. + 5CaCI, Chloride of calcium. 2H,0 Water. This is the official process, and may be imitated on the small scale after adding a minute piece of iron to a frag- ment of the marble before dissolving in acid. The names, formulae, and reactions of these compounds of iron will be best understood when that metal comes under treatment. Oxide of Calcium (Quick Lime). Second Synthetical Reaction , — Place a small piece of chalk in a strong grate-fire or furnace and heat until a trial fragment, chipped off from time to time and cooled, no longer effervesces on the addition of acid ; caustic lime, CaO {Calx,^ B. P. and XJ. S. P.), remains. CaC 03 = CaO + CO, Carbonate of Oxide of Carbonic calcium (chalk). calcium (lime). acid gas. Note . — Etymologically considered, this action is anylytical (dm- ^uco, analuo, I resolve) and not synthetical sunthesis, a putting together) ; but conventionally it is synthetical, and not analytical ; for in this, the usual sense, and the sense in which the words are used throughout this book, synthesis is the application of chemical action with the view of producing something, analysis the application of chemical action with the view of finding out the com- position of a substance. In the etymological view of the matter there is scarcely an operation performed either by the analyst or by the manufacturer but includes both analysis and synthesis. Lime-kilns . — On the large scale the above operation is carried on in what are termed lime-kilns [Kiln, Saxon, cyln, from cylene, a furnace). Hydrate of Calcium (Slaked Lime). Slaked Lime , — When cold, add to the lime about half its weight of water, and notice the evolution of steam and 92 THE METALLIC RADICALS. other evidence of strong action ; the product is slaked lime or hydrate of calcium (Ca2H0) {Galcis hydras^ B. P.), with whatever slight natural impurities the lime might contain. The slaking of hard or stony^^ lime may be accelerated by using hot water. CaO -p H^O = Ca2H0 Lime. Water. Hydrate of calcium (slaked lime). Lime-water. — Place the hydrate of calcium in about a hundred times its weight of water: in a short time a satu- rated solution, known as lime-water {Liquor Calais^ B. P. and U. S. P.), results. It contains about IG grains of hydrate of calcium (Ca2H0), equivalent to about 11 or 12 grains of lime (CaO), in one pint. Strong Solution of Lime . — Slaked lime is much more soluble in aqueous solution of sugar than in pure water. The Liquor Calcis Saccharatus, B. P., is such a solution, containing 2 ounces of sugar and 188 grains of hydrate of calcium (Ca2H0), equivalent to 142 grains of lime (CaO), in 1 pint. It is a more efficient precipitant of hydrates and carbonates than lime-water. The official process is as follows : Mix 1 ounce of lime and 2 of sugar by trituration in a mortar. Transfer the mixture to a bottle containing 1 pint of water, and, having closed this with a cork, shake it occasionally for a few hours. Finally separate the clear solution with a siphon and keep it in a stoppered bottle. Solutions of hydrate of calcium absorb carbonic acid gas on ex- posure to air, a semicrystalline precipitate of carbonate being deposited. When the saccharated solution is heated, there is preci- pitated a compound of three molecules of lime with one of sugar. Carbonate of Calcium. Third Synthetical Reaction. — To a solution of chloride of calcium add excess of carbonate of sodium, or about 5 parts of dry chloride to 13 of carbonate; a white preci- pitate of carbonate of calcium ( Galcii Garhonas Praecijpi- tata.^ U. S. P.), (CaCOg) results. If the solutions of the salts be made hot before admixture, and the whole set aside for a short time, the particles aggregate to a greater extent than when cold water is used, and the product is finely granular or slightly crystalline. The official variety is thus prepared. CaCl, + Na,C 03 = CaC 03 + 2NaCl Chloride of Carbonate of Carbonate of Chloride of calcium. sodium. calcium. sodium. Collect and purify this Precipitated Ghalk b}" pouring the mixture into a paper cone supported by a funnel, and, CALCIUM. 93 when the liquid has passed through the filter, pour water over the precipitate three or four times until the whole of the chloride of sodium is washed away. This operation is termed washing a precipitate. When dry {;mde Index, “ Drying precipitates’’) the precipitate is fit for use. Filtering-paper, or hibulous-paper (from hiho, to drink), is simply good unsized paper made from the best white rags — white blotting- paper, in fact, of unusually good quality. Students’ or analysts’ filters, on which to collect precipitates, are round pieces of this paper, from three to six inches in diameter, twice folded, and then opened out so as to form a hollow cone. Square pieces are rounded by scissors after folding. The cone is supported by a glass or earthenware funnel. Washing-bottle. — Precipitates are best washed by a fine jet of water directed on to the different parts of the filter. A common narrow-necked bottle of about half-pint capacity is fitted with a cork ; two holes are bored through the cork, the one for a glass tube reach- ing to the bottom of the bottle within, and externally bent to a slightly acute angle, the other for a tube bent to a slightly obtuse angle, the inner arm terminating just within the bottle. The outer arms may be about 3 inches in length. The extremity of the outer arm continuous with the long tube should be previously drawn out to a fine capillary opening by holding the original tube, before cut- ting, in a flame, and, when soft, gently pulling the halves away from each other fintil the heated portion is reduced to the thinness of a knitting-needle. The tube is now cut at the thin part by a file, and the sharp edges rounded off by placing in a flame for a second or two. The outer extremity of the shorter tube should also be made smooth in the flame. The apparatus being put together, and the bottle nearly filled with water, air, blown through the short tube by the lungs, forces water out in a fine stream at the capillary orifice. Decantation. — Precipitates may also be washed by allowing them to settle, pouring off the supernatant liquid, agitating with water, again allowing to settle, and so on. This is washing by decantation [de, from, canthus, an edge). If a stream of liquid flowing from a basin or other vessel exhibits any tendency to run down the outer side of the vessel, it should be guided by a glass rod placed against the point whence the stream emerges. If the vessel be too large to handle with convenience, the wash- water may be drawn off by a siphon. A siphon is a tube of glass, metal, gutta-percha, or India-rubber, bent into the form of a Y or U, filled with water, and inverted ; one end immersed in the wash-water, and the other allowed to hang over the side of the vessel ; so long as the outer orifice of the instrument is below the level of the liquid in the vessel, so long will that liquid flow from within outwards until the vessel be empty.* * The nature of the action of a syphon is simple. The column of water in the outer limb is longer, and therefore heavier, than the column of similar area in the inner limb. (The length of the inner limb must be reckoned from the surface of the liquid, the portion 94 THE METALLIC RADICALS. Prepared carbonate of calcium [Creta Prceparata, B. P. and U. S. P.) is merely washed chalk [Creta, B. P. and U. S. P.) or loliiting, only that in Pharmacy fashion demands that the chalk be in little conical lumps, about the size of thimbles, instead of in the larger rolls characteristic of “ whiting.” Wet whiting pushed, por- tion by portion, through a funnel, and each separately dried, gives the conventional Creta Prceparata. Its powder is amorphous. Testa Prceparata, U. S. P., is powdered oyster-shell, similarly treated. It is an inferor kind of prepared chalk. Phosphate of Calcium. Fourth Synthetical Reaction. — Digest bone-ash (bones burnt in an open crucible with free access of air till all animal and carbonaceous matter has been removed — im- pure phosphate of calcium {Os Ustum^ B. P.)) with nearly twice its weight of hydrochloric acid (diluted with three or four times its bulk of water) in a test-tube or larger vessel ; the phosphate is dissolved. Ca 32 PO, + 4HC1 = CaHSPO, Phosphate of calcium (impure). Hydrochloric acid. Acid phosphate of calcium. + 2CaCI, Chloride of calcium. Dilute with water, filter, boil, and w^hen cold add excess of solution of ammonia ; the phosphate of calcium, now pure (Galcis Phosphas^ B. P.; Calcii Phosphas Precipitata^ U. S. P.), is reprecipitated as a light white amorphous powder. After well washing, the precipitate should be dried over a water-bath {ride Index), or at a temperature not exceeding 512^, to prevent undue aggregation of the particles. Ca 32 PO, -f 4AmCl Phosphate Chloride of of calcium ammonium, (pure). CaH,2PO^ + Acid phosphate of calcium. 2CaCl, + 4AmHO Chloride Ammonia, of calcium. + 4II,p Water. Bone-ash or bone-earth contains small quantities of car- bonate and sulphide of calcium. These are decomposed in the above process by the acid, chloride of calcium being formed; on boiling the mixture, carbonic acid gas and sul- below the surface playing no part in the operation). Being heavier, it naturally falls by gravitation, the liquid in the shorter limb instantly following, because pressed upwards by the air. The air, be it ob- served, exerts a similar amount of pressure on the liquid in the outer limb: in short, atmospheric pressure causes the retention of liquid in the instrument, while gravitation determines the direction of the flow. CALCIUM. 95 pliuretted hydrogen gas are evolved. Any carbonaceous or siliceous matter, etc., is removed by filtration. In bones the phosphate of calcium is always accompanied by a small quantity of an allied substance, phosphate of magnesium ; a trace of fiuoride of calcium (CaF 2 ) is also present. Bone-black^ or Animal Charcoal {Garbo Animalis^ B. P. and U. S. P.), is the residue obtained on subjecting dried bones (Os, IJ. S. P.) to a red heat without access of air. The operation may be imitated by heating a few fragments of bone in a covered porcelain crucible in a fume-chamber until smoke and vapor cease to be evolved. Purified Ani- mal Charcoal {Garbo Animalis FuriJicatus^B, P. and U. S. P.) is obtained by digesting animal charcoal (16 parts) in hydrochloric acid (10 parts) and water (20 parts) in a warm place for a day or two, filtering, thoroughly washing, drying over a water-bath, and igniting the product in a closely covered crucible. The reaction is the same as that just described ; that is to say, the acid removes the phosphate of calcium from the carbon of animal charcoal by forming soluble acid phosphate and chloride of calcium. Wood Charcoal ( Garbo Ligni^ B. P. and U. S. P.) is wood similarly ignited without access of air. Decolorizing power of Animal Charcoal. — Animal char- coal, in small fragments, is the material emploj^ed in de- colorizinsf solutions of common brown su^arwith the view of producing white lump sugar. Its power and the nearly equal power of an equivalent quantity of the purified va- riety may be demonstrated on solution of litmus or log- wood. Phosphate of Sodium — Phosphate of calcium is con- verted into phosphate of sodium {Sodii Phosphas., U. S. P.) (Na 2 HP 04 , 12 H 20 ) as follows: Mix, in a mortar, 3 ounces of ground bone-earth with 1 fluidounce of sulphuric acid; set aside for twentj^-four hours to promote reaction ; mix in about 3 ounces of water, and put in a warm place for two days, a little water being added to make up for that lost by evaporation ; stir in another 3 ounces of water, warm the whole for a short time, filter, and wash the residual sulphate of calcium on the filter to remove adhering acid phosphate of calcium; concentrate the (the liquid portion), which is a solution of acid phosphate of calcium, to about 3 ounces, filter again, if necessary, add solution of (about 4^ ounces of crystals of) carbonate of sodium to the hot filtrate until a precipitate (a phosphate of calcium, 96 THE METALLIC RADICALS. CaHPO^), ceases to form, and the fluid is faintly alkaline ; Alter, evaporate, and set aside to ciystallize. Phosphate of sodium occurs ‘‘ in transparent colorless rhombic prisms, terminated b^- four converfying planes, efflorescent, tasting like common salt.’’ One part in ten of water constitutes ‘‘ Solution of Phosphate of Soda,” B. P. This is an official as well as the ordinary process. The following equations show the two decompositions which occur during the operations: — Ca 32 PO, + 2H,SO, = CaH,2PO, -f 2CaSO, Phosphate Sulphuric Acid phosphate Sulphate of of calcium acid. of calcium. calcium. CaH,2PO, + Na^CO, = Na,HPO, + H,0 Acid phosphate Carbonate Phosphate of Water, of calcium. of sodium. sodium. + CO, + CaHPO, Carbonic Phosphate acid gas. of calcium. Ordinary phosphate of sodium (Na^HPO^, 12H.^O) efflo- resces rapidly in the air until nearly half its water has escaped, when it has a permanent composition represented by the formula Na^HPO^, Hypochlorite of Calcium. Fifth Synthetical Reaction Pass chlorine, generated as already described, into damp slaked lime contained in a piece of wide tubing, open at the opposite end to that in which the deliveiy-tube is fixed. (A test-tube, the bottom of which has been accidentally broken, is very convenient for such operations.) The product is ordinaiy bleaching- powder^ said to be a mixture of hypochlorite and chloride of calcium, commonly called chloride of lime^ Calx chlo- rata^ B. P. {Calx Chlorinata^ U. S. P.). MnO^ -f 4HC1 = MnCl^ + 2H,0 + Cl, Black oxide Hydrochloric Chloride of Water. Chlorine.^, of manganese. acid. manganese. N 2CaH,0, + 2C1, := 2H,0 + CaCl,0, , CaCl, \ Hydrate of Chlorine. Water. Hypochlorite Chloride j calcium. of calcium, of calcium. Chlorinated lime, exposed to air and moisture, as in disinfecting the air of sick rooms, slowly yields hypochlorous acid (HCIO). Free hypochlorous acid soon breaks up into w’ater, chloric acid (IICIO-J, and free chlorine. Chloric acid is also unstable, decomposing into oxygen, water, chlorine, and perchloric acid (HCIO4), The small quantity of hypochlorous acid, diffused through an apartment when CALCIUM. 91 bleaching-powder is exposed thus, yields fourteen-fifteenths of its chlorine in the form of chlorine gas — one of the most efficient of known disinfectants. Bleaching-liquor,, — Digest chlorinated lime in water, in which the bleaching compound is soluble, filter from the undissolved lime, and test the bleaching-powers of the clear liquid by adding a few drops to a decoction of log- wood slightly acidulated. One pound of this bleaching- powder, shaken several times during three hours, with 1 gallon of water, forms Solution of Chlorinated Lime {Liquor Galcis Chloratse^ B. P.). Gummate of Calcium, Gummate of Calcium is the only official calcium salt that remains to be noticed. This compound is, in short, arahin^ the ordinary Gum-Acacia, or Gum-Arabic {Acacise Gummi^ B. P., and U. S. P.), a substance too well known to need description. A solution of gum-arabic in water (Mucilago Acaciw, B. P. and LT. S. P.) yields a white pre- cipitate of oxalate of calcium on the addition of solution of oxalate of ammonium. Or a piece of gum burnt to an ash in a porcelain crucible yields a calcareous residue, which, dissolved in dilute acids, affords characteristic re- actions with any of the following analytical reagents for calcium. The gummic radical may be precipitated as opaque gelatinous gummate of lead by the addition of solution of oxyacetate of lead {Liquor Flumbi Suhacetatis^ B. P.) to an aqueous solution of gum. These statements may be experimentally verified by the practical student. Tragacanth {Tragacantha, B. P. and U. S. P.) is usually consid- ered to be a mixture of soluble gum or arabin and a variety of cal- cium gum insoluble in water, termed hassorin : Guibourt thought it to be gelatinoid. With water a gelatinous mucilage is formed [Mucilago Tragacanthce, B. P. and U. S. P.). Reactions having Analytical Interest (Tests). First Analytical Reaction. — Add sulphuric acid, highly diluted, to a calcium solution contained in a test-tube or small test-glass; sulphate of calcium (CaSO^, 211^0) is formed, but is not precipitated, it being, unlike sulphate of barium, slightly soluble in water. Solution of Sulphate of Calcium. — A quarter of an ounce of that (dried) form of sulphate of calcium known as plaster of Paris (CaSO^) 9 98 THE METALLIC RADICALS. digested in one pint of water for a short time, with occasional shak- ing, and the mixture filtered, yields the official test-liquid termed “ Solution of Sulphate of Lime,” B. P. About 400 parts of the solu- tion contain 1 of sulphate of calcium. Second Analytical Reaction . — Add yellow chromate of potassium (K^CrOJ to a calcium solution slightly acidified with acetic acid ; chromate of calcium (CaCrOJ is pro- bably formed, but it is not precipitated. Barium is preci- pitated by the chromic radical. These two negative reactions are most valuable in analysis, as every precipitant of calcium is also a precipitant of barium ; but the above two reagents are precipitants of barium only. Hence calcium, which when alone can be readily detected by the following reactions, cannot by any reaction be detected in the presence of barium. But by the sulphuric or chromic test barium is easily removed, and then either of the following reagents will throw down the calcium. Other Analytical Reactions . — Add carbonate of ammo- nium, phosphate of sodium, arseniate of ammonium, and oxalate of ammonium to calcium solutions as described under the analj^tical reactions of barium, and write out descriptive equations. The precipitates correspond in ap- pearance to those of barium ; their constitution is also identical, hence their correct formulae can easily be deduced. Of these precipitants oxalate of ammonium is that most commonly used as a reagent for calcium salts, barium being absent. The oxalate of calcium is insoluble in acetic, but soluble in hydrochloric or nitric acids. Calcium compounds impart a reddish color to the flame. QUESTIONS AND EXEECISES. 143. Enumerate some of the common natural compounds of cal- cium. 144. Explain, by an equation, the action of hydrochloric acid on marble. What official compounds result ? 145. Why is chloride of calcium used as a desiccator for gases ? 146. How would you purify Chloride of Calcium which has been made from ferruginous marble ? Give diagrams. 147. Write a few lines on the chemistry of the lime-kihi. 148. In what sense is the conversion of chalk into lime an analy- tical action ? 149. What occurs when lime is slaked ? 150. To what extent is lime soluble in water ? to what in syrup ? 151. Describe the preparation of the official Precipitated Carbo- nate of Calcium ; in what does it differ from Prepared Chalk ? MAGNESIUM. 99 152. In wliat does filtering-paper differ from other kinds of paper ? 153. Explain the construction of “ a washing bottle’’ for cleansing precipitates by water. 154. Define decantation. 155. Describe the construction and manner of employment of a siphon. 156. Explain the mode of action of a siphon. 157. What is the difference between Bone, Bone-earth, and Pre- cipitated Phosphate of Calcium ? 158. How is “ Bone-earth” purified for use in medicine ? 159. Explain the action of hydrochloric acid on Animal Charcoal in the conversion of Carbo Animalis into Carho Animalis Purifi- catus. 160. What is the chemical difference between Carlo Animalis and Carbo Ligni? 161. Give equations showing the conversion of Phosphate of Cal- cium into Phosphate of Sodium. 162. Write a short article on the manufacture, composition, and uses of bleaching-powder.” 163. How may calcium be detected in Gum-Arabic? 164. State the chemical nature of Tragacanth. 165. To w^hat extent is sulphate of calcium soluble in water ? 166. Can calcium be precipitated from an aqueous solution con- taining barium ? 167. Barium being absent, what reagents may be used for the de- tection of calcium ? Which is the chief test ? MAGNESIUM. Symbol Mg. Atomic weight 24. Source. — Magnesium is abundant in nature in the form of magne- sian or mountain limestone, or dolomite, a double carbonate of mag- nesium and calcium in common use as a building-stone [e. g. the Houses of Parliament, and the School of Mines in London), and magnesite, a tolerably pure carbonate of magnesium, though too ‘•stony” for direct use in medicine, even if very finely powdered. Chloride of magnesium and sulphate of magnesium (Epsom salt) also occur in sea-water and the water of many springs. Metallic magne- sium may be obtained from the chloride by the action of sodium. It burns readily in the air, emitting a dazzling light due to the white heat to which the resulting particles of magnesia (MgO) are exposed. The chloride employed as a source of the metal is obtained by dis- solving the carbonate in hydrochloric acid, adding some chloride of ammonium, evaporating to dryness, heating the residue • in a flask (on the small scale a large test-tube or Florence flask) until the chlo- ride of ammonium is all volatilized and the chloride of magnesium remains as a clear fused liquid. The latter is pouted on to a clean earthenware slab. The chloride of ammonium prevents reaction between chloride of magnesium and water in the last stages of the 100 THE METALLIC RADICALS. operation and consequent formation of oxide (or oxychloride) of magnesium and hydrochloric acid gas. Quantivalence . — The atom of magnesium is bivalent, Mg". Reactions having Synthetical Interest. Sulphate of Magnesium. First Synthetical Beaction. — To a few drops of sulphuric acid and a little water in a test-tube (or to larger quanti- ties in larger vessels), add carbonate of magnesium (pre- ferably the native carbonate magnesite^ MgCO^) until effer- vescence ceases, subsequently boiling to aid in the expul- sion of the carbonic acid gas. The filtered liquid is a solu- tion of sulphate of magnesium (MgSOJ, crystals of which, Epsom salt (MgSO^, 7H.^O) {Magnesii Sulphas^ U. S. P.), may be obtained on evaporating most of the water, and set- ting the concentrated solution aside to cool. This is an ordi- nary manufacturing process. Instead of magnesite, dolo- mite^ the common magnesian limestone (CaCO.^, MgCOg) may be employed, any iron being removed by evaporating the solution (filtered from the sulphate of calcium produced) to dryness, gently igniting to decompose sulphate of iron, dissolving in water, filtering from oxide of iron, and crys- tallizing. MgC03 + H,SO, = MgSO, + 11,0 + CO, Carbonate of Sulphuric Sulphate of Water. Carbonic magnesium. acid. magnesium. acid gas. Sulphate of magnesium readily crystallizes in large, colorless, transparent, rhombic prisms ; but, from concentrated solutions, the crystals are deposited in short thin needles, a form more convenient for manipulation, solution, and general use in medicine. Iron may be detected in sulphate of magnesium by adding the common alkaline solution of chlorinated lime or chlorinated soda to an aqueous solution of the salt ; brown hydrate of iron (Fe26HO) being precipitated. Sulphydrate of ammonium will also give a black precipitate if iron be present. Carbonates of Magnesium. Second Synthetical Reaction. — To solution of sulphate of magnesium add solution of carbonate of sodium and boil ; the resulting precipitate is light carbonate of mag- nesium {Ma.gnesise Carhoiias Levis.^ B. P., Magnesii Car- honas., U. S. P.), a white, partly amorphous, partly minutely crystalline mixture of carbonate and h^^lrate of magnesium (SMgCO^, Mg2IIO, 411^0). A denser, slightly granular MAGNESIUM. 101 precipitate of similiar chemical composition {Magnesiw Gar- bo 7 ias, B. P.) is obtained on mixing strong solutions of the above salts, evaporating to dryness, then removing the sul- phate of sodium by digesting the residue in hot water, filter- ing, washing, and drying the precipitate. 4MgSO, Sulphate of magnesium. + + 4Na2C03 Carbonate of sodium. 4Na,SO, Sulphate of sodium. + H,0 = Water. + SMgCOg, Mg2HO Official carbonate of magnesium. CO, Carbonic acid gas. The official proportions for the light carbonate are 10 of sulphate . of magnesium and 12 of crystals of carbonate of sodium, each dis- solved in 80 of cold water, the solutions mixed, boiled for 15 minutes, the precipitate collected on a filter, well washed, drained, and dried over a water-bath. The heavier carbonate is made with the same proportions of salts, each dissolved in 20 instead of 80 of water, the mixture evaporated quite to dryness, and the residue washed by decantation or filtration until all sulphate of sodium is removed (shown by a white precipitate — sulphate of barium — ceasing to form on the addition of solution of chloride or nitrate of barium to a little of the filtrate). Third Synthetical Reaction, — Pass carbonic acid gas, generated as described on page 61, into a mixture of water and carbonate of magnesium contained in a test-tube. After some time, separate undissolved carbonate by filtra- tion ; the filtrate contains carbonate of magnesium dissolved by carbonic acid. When of a strength of about 13 grains in one ounce, the solution constitutes Fluid Maynesia^^ {Liquor Magne8iae Garhonatis,^ B. P.). Officially, 1 pint is directed to be made from freshly prepared car- bonate. The latter is obtained by adding a hot solution gf 2 ounces of sulphate of magnesium in half a pint of water to one of 2 ^ ounces of crystals of carbonate of sodium in another half pint of water, boiling the mixture for a short time (to complete decomposition), filtering, thoroughly washing the precipitate, placing the latter in 1 pint of distilled water, and transmitting carbonic acid gas through the liquid (say, at the rate of three or four bubbles per second) for an hour or two, then leaving the solution in contact with the gas under slight pressure for twenty-four hours, and, finally, filtering from undissolved carbonate, and, after passing in a little more gas, keeping in a well-corked bottle. Slight pressure is best created by placing the carbonate and water in a bottle fitted with a cork and tubes as for a wash-bottle (p. 81 or 93), conveying the gas by a tube which reaches to the bottom, and allowing excess of gas to flow out by the upper tube, the external end of which is continued to the bottom of a common phial containing about an inch of mercury. 9* 102 THE METALLIC RADICALS. The phial should be loosely plugged with cotton-wool, to prevent loss of metal by spurting during the flow of the gas through it. (Each inch in depth of mercury through which the gas escapes corre- sponds to about half-a-pound pressure on every square inch of surface within the apparatus.) Heat a portion of the solution ; true carbonate of magnesium con- taining combined water (MgC03,3H20) is precipitated. The water in this compound is probably in the state of water of crystallization, for a salt having the same composition is deposited in crystals by the spontaneous evaporation of the solution of carbonate of mag- nesium. The official “ carbonate” (3MgC03,Mg2H0,4H20) is another of these very common hydrous compounds. Exposed to cold, the solution of “fluid magnesia” sometimes affords large thick crystals (MgC03,5H20), which, in contact with the air, lose water, become opaque, and then have the composition of those deposited by evaporation (MgC03,3H20). Liquor Magnesii Citratis^ U. S. P., is a solution of carbonate of magnesium and bicarbonate of potassium in excess of citric acid and syrup of citric acid. Oxide of Magnesium (Magnesia). Fourth Synthetical Reaction, — Heat light dry carbonate of magnesium in a porcelain crucible over a lamp (or in a larger earthen crucible in a furnace) till it ceases to effer- vesce on adding, to a small portion, water and acid ; the residue is light magnesia (MgO) {Magnesia Levis^ B. P.). The same operation on the heavy carbonate yields heavy magnesia (MgO) {Magnesia,^ B. P). Both are sometimes spoken of as calcined magnesia^’ {Magnesia,^ U. S. P.) A given weight of the official light magnesia occupies three and a half times the bulk of the weight of heavy magnesia. 3MgC03,Mg2H0 = 4MgO + H 2 O + 3 CO 2 Official carbonate of Oxide of Water. Carbonic magnesium. magnesium. acid gas. A trace only of magnesia is dissolved by pure water. Moisten a grain or two of magnesia with w^ater, and place the paste on a piece of red litmus-paper; the wet, spot, after a time, becomes blue, showing that the magnesia is slightly soluble. Reactions having Analytical Interest (Tests). First Analytical Reaction. — Add solution of hydrate or carbonate of ammonium to a magnesian solution (sulphate for example) and boil the mixture in a test-tube ; the pre- cipitation of part only of the magnesium as 113 'drate (Mg 2 HO) or carbonate (MgC 03 ) occurs. Add now to a MAGNESIUM. 103 small portion of the mixture of precipitate and liquid a considerable excess of solution of chloride of ammonium ; the precipitate is dissolved. This is an important reaction, especially as regards carbonate of magnesium, the presence of chloride of ammonium enabling the analyst to throw out from a solution barium and calcium by an alka- line carbonate, magnesium being retained. The cause of this reac- tion is the tendency of magnesium to form soluble double salts with potassium, sodium, or ammonium. In analysis, the chloride of am- monium should be added before the carbonate, as it is easier to pre- vent precipitation than to redissolve a precipitate once formed. Second Analytical Reaction . — To some of the solution resulting from the last reaction, add solution of phosphate of sodium or ammonium; phosphate of magnesium and ammonium (MgNH^POJ is precipitated. 36?. To another portion add arseniate of ammonium ; arseniate of magne- sium and ammonium (MgNH^AsO^) is precipitated. Note. — Barium and calcium are also precipitated by alkaline phos- phates and arseniates. The other precipitants of magnesium are also precipitants of barium and calcium. In other words, there is no direct test for magnesium. Hence the analyst always removes any barium or calcium by an alkaline carbonate, as above indicated ; the phosphate of sodium or arseniate, or phosphate of ammonium, then become very delicate tests of the presence of magnesium. In speaking of magnesium tests, the absence of barium and calcium salts is to be understood. QUESTIONS AND EXEKCISES. 168. Name the natural sources of the various salts of magnesium. 169. Give a process for the preparation of Epsom salt. 170. Draw diagrams illustrative of the formation of sulphate of magnesium from magnesite and from dolomite. 171. Show by an equation the process for the preparation of the official Carbonate of Magnesium. 172. What circumstances determine the two different states of aggregation of the Magnesice Carbonas and Magnesice Carhonas Levis ? 173. What are the relations of Magnesia dvadi Magnesia Levis to the official Carbonates of Magnesium ? 174. How much denser is the one than the other? 175. Is magnesia soluble in water? 176. How is “Fluid Magnesia” prepared? 177. Mention the effects of heat and cold on “Fluid Magnesia.” 178. How much magnesia (MgO) can be obtained from 100 grains of Epsom Salt ? 104 THE METALLIC RADICALS. 179. Calculate the amount of official Carbonate of Magnesium which will yield 100 grains of magnesia. 180. Can magnesium be detected in presence of barium and cal- cium? 181. Describe the analysis of an aqueous liquid containing salts of barium, calcium, and magnesium. 182. How may magnesium be precipitated from solutions con- taining ammoniacal salts ? Quantivalence. On reviewing the foregoing statements regarding compounds of the three univalent radicals, potassium, sodium, and ammonium, and the three bivalent elements, barium, calcium, and magnesium, the doctrine of quantivalence will be more clearly understood, and its usefulness more apparent. Quantivalence, or the value of atoms, is, in short, in chemistry, closely allied to value in commercial barter. A number of articles, differing much in weight, appearance, and general characters, may be of equal money value ; and if these be regarded, for convenience, as having a sort of unit of value, others worth double as much might be termed bivalent, three times as much trivalent, and so on. In like manner, chemical radicals, no matter whether elementary, like potassium (K), iodine (I), or sul- phur (S), or compound, like those of nitrates (NOg), sulphates (SO^), or acetates (C2H3O.J, have a given chemical value in relation to each other, and are exchangeable for, and will unite with each other to an extent determined by that value. Most chemical salts apparently, though probably not really, have two parts, a basylous and an acidulous, the one quantivalently bal- ancing the other. The formulae of the chief of these radicals and their quantivalence are given below. Examples of formulae of salts containing univalent, bivalent, and trivalent radicals are also ap- pended. Quantivalence of Common Radicals. Univalent Radicals, or Monads. Bivalent Radicals, or Dyads. Trivalent Radicals, or Triads. Acidulous. Basylous Acidulous. Basylous. Acidulous. Basylous. H H 0 Ca PO* As Cl K so* Mg BO, Sb I Na CO, Zu CA5O, Bi HO NH, cA Cu AsO, f Fe“*(ic) NOg c*n*o, Hg(ic) AsO* J or c,ri,o, Hg(ous) s Fe(ous) 0*1130, 1 Fe''‘,(ic) Note . — The hydrogen (II) in the basylous parts of salts has en- tirely different functions to the hydrogen (H) in the acidulous part. QUANT I VALENCE. 105 The latter gives compounds commonly termed hydrides (e, g. CuH^) ; ill the former the element is the basylous radical of acids (e. g. HCl, H.^SO^). In compound radicals, e. g. O2H3O2 or NH^, the proper- ties of hydrogen are no longer apparent : the chemical force resident with the atoms of such radicals seems to be mainly exerted in binding those atoms together. Examples of Formulae containing Univalent, Bivalent, and Tri valent Radicals. The reader will find instructive practice in writing twenty or thirfy imaginary formulae of salts by placing in juxtaposition acidulous and basylous radicals, as in the following examples. Just as in a pair of scales a 2-lb. weight must be balanced by two 1-lb. weights, or a 4-lb. weight by two 2-lb. weights, or by one 3-lb. and one 1-lb. weight, so a bivalent radical unites with a bi- valent radical or with two univalent radicals, a quadrivalent radical with two bivalent radicals, or with one trivalent and one univalent radical, and so on. (R = any basylous Radical.) {R = any acidulous Radical.) General formula, WR' WR\ W"R'^ R\R'' I U'U'R" I K,R'" . . . . ) W,R'R'" .... I R"R" R"R'R'" R'"R"R R"',R'\R" R"\R", R'"R'" R tn Tit/ Examples. KI, NaCl, AgN03. CaCl^, Zn2C2H302, Pb2N03(BaN03C2H302). Bi3N03, ASH 3 , SbCl 3 . K,C03, Na^SO,, II^C.H.O,. KilC03, NaHSO^, KHO^H^O^. Am3PO„ K3C6H5O7, H3ASO3. Na^HPO,, Na.HAsO,. CaC03,Mg0, CuSO„ HgO, FeSO^. Ca32P04, Oa32C,H50,. MgAmPO,, CUHASO3. BiONO,. Bi 202 C 03 . AS2O3, Sb203. BiO.H^O^. Fe2Cl6, Fe 26 N 03 , Fe26C2H302. Fe203, Fe 23 SO,. Quadrivalent Radicals or Tetrads, Quinquivalent Radicals or Pen- tads, and Sexivalent Radicals or Hexads, are known. EXERCISE. 183. Write an exposition of the doctrine of Qnantiva- lence within the limits of a sheet of note paper. 106 THE METALLIC RADICALS. DIRECTIONS FOR APPLYING THE FOREGOING ANALYTICAL RE- ACTIONS TO THE ANALYSIS OF AN AQUEOUS SOLUTION OF A SALT OF ONE OF THE METALS, BaRIUM, CaLCIUM, MAG- NESIUM. Add yellow chromate of potassium to a portion of the solution to be examined; a precipitate indicates barium. If no barium is present, add chloride and carbonate of ammonium, and boil; a precipitate indicates calcium. If barium and calcium are proved to be absent, add chlo- ride of ammonium, ammonia, and then either phosphate of sodium or arseniate of ammonium ; a white granular pre- cipitate indicates magnesium. Ammonia is here added to yield the necessary elements to ammo- nio-magnesian phosphate or ammonio-magnesian arseniate, both of which are highly characteristic precipitates ; and chloride of ammo- nium is added to prevent a mere partial precipitate of the magnesium by the ammonia. DIRECTIONS FOR APPLYING THE FOREGOING ANALYTICAL RE- ACTIONS TO THE ANALYSIS OF AN AQUEOUS SOLUTION OF ONE, TWO. OK Aljli THREE OF THE METALS, BaRIUM, Calcium, Magnesium. Add chromate of potassium to the solution ; barium, if present, is precipitated. Filter, if necessary, and add to the filtrate (that is, the liquid which has run through the filter) chloride, hydrate, and carbonate of ammonium, and boil; calcium, if present, is precipitated. Filter, if requi- site, and add phosphate of sodium ; magnesium, if present, is precipitated. Note . — Eed chromate of potassium must not be used in these ope- rations, or a portion of the barium will remain in the liquid and be thrown down with, or in place of, the carbonate of calcium {vide p. 88). The yellow chromate must not contain carbonate of potas- sium, or calcium will be precipitated with, or in place of, barium. The absence of carbonate is proved by the non-occurrence of effer- vescence on the addition of hydrochloric acid to a little of the solu- tion of the chromate, previously made hot in a test-tube. If the yellow chromate has been prepared by adding excess of ammonia to solution of red chromate of potassium, its addition to the liquid to be analyzed must be preceded by that of solution of chloride of am- monium ; the precipitation of a portion of the magnesium (by the free ammonia in the yellow chromate) is thus prevented, for chloride of ammonium solution is a good solvent of hydrate (and carbonate) of magnesium. BARIUM, CALCIUM, MAGNESIUM. lOT TABLE OF SHORT DIRECTIONS FOR APPLYING THE FOREGOIN-G ANALYTICAL REACTIONS TO THE ANALYSIS OF AN AQUEOUS SOLUTION OF SALTS CONTAINING ATsTY OK ALL OF THE ME- TALLIC ELEMENTS HITHERTO CONSIDERED. To the solution add AmCl, AmHO, Am^COg; boil and filter. Precipitate Ba Oa. Wash, dissolve in HC2H3O2, add K2Cr04, and filter. Filtrate Mg Am Na K. Add Am2HP04, shake, filter. Precipitate Filtrate Precipitate Filtrate Ba Ca. Test by AiBjO.O^. Mg. Am Na K. Evap. to dryness, ignite, dissolve residue in water. Test for K by Pt Cl^. Test for Na by fiame. Test orig. sol. for Am. Note 1 . — The analysis of solutions containing the foregoing metals is commenced by the addition of chloride of ammonium (AmCl) and ammonia (AmHO), simply as a precautionary measure, the former compound preventing partial precipitation of magnesium, the latter neutralizing acids. The carbonate of ammonium (Am.^COg) is the important group-reagent — the precipitant of barium and calcium. Note 2. — In the above, and in subsequent charts of analytical processes, the leading precipitants will be found to be ammonium salts. These, being volatile, can be got rid of towards the end of the operations, and thus the detection of potassium and sodium be in no way prevented — an advantage which could not be had if such salts as chromate of potassium or phosphate of sodium were the group- precipitants employed. Note 3 . — Acetic, and not hydrochloric or Iiitric, acid is used in dissolving the barium and calcium carbonates, because chromate of barium, on the precipitation of which the detection of barium de- pends, is soluble in the stronger acids, and therefore could not be thrown down in their presence. Note on Classification . — The compounds of barium, calcium, and magnesium, like those of the alkali metals, have many analogies ; the carbonates, phosphates, and arseniates of each are insoluble, which sufficiently distinguishes them from the members of the class first studied. They possess, moreover, well-marked differences, so that their separation from each other is easy. The solubility of their hydrates in water marks their connection with the alkali metals ; the slightness of that solubility, diminishing as we advance further and further from the alkalies, baryta being most and magnesia least 108 THE METALLIC RADICALS. soluble in water, points to their connection with the next class of metals, the hydrates of which are insoluble in water. These con- siderations must not, however, be over-valued. Though the solu- bility of their hydrates places barium nearest and magnesium furthest from the alkali metals, the solubility of their sulphates gives them the opposite order, magnesium-sulphate being most soluble, calcium- sulphate next, strontium-sulphate third (strontium is a rarer element, which will be mentioned subsequently), and barium sulphate insoluble in water. These elements are sometimes spoken of as the metals of the alkaline earths. Note. — In connection with the bivalence of the metals Barium, Calcium, and Magnesium, it is interesting to note that just as biva- lent acidulous radicals give salts containing two atoms of univalent basylous radicals (K.^SO^, NaHSO^, H2CO3, KNaC4H^03), so biva- lent basylous radicals yield salts containing tw^o atoms of univalent acidulous radicals, as seen in acetonitrate of barium, BaC2H302^"^3» a salt w^hich is a definite compound, and not a mere mixture of ace- tate wfith nitrate of barium. A very large number of such salts is known. Distillation. The water with w^hich, in analysis, solution of a salt or dilution of a liquid is effected should be pure. Well or river-w^ater [Aqua, U. S. P.) is unfit for the purpose, because containing alkaline and earthy salts (about 20 to 60 grains per gallon), derived from the soil through w^hich the water percolates, and rain-w^ater is not unfre- quently contaminated wuth the dust and debris which fall on the roofs whence it is usually collected. Such w^ater is purified by dis- tillation, an operation in which the w^ater is by ebullition converted into steam, and the steam condensed again to w'ater in a separate vessel, the fixed earthy and other salts remaining in the vessel in w^hich the wmter is boiled. On the large scale, ebullition is effected in metal boilers having a hood or head in which is a lateral opening through which passes the steam ; on the small scale, either a common glass flask is employed, into the neck of which, by a cork, is inserted a glass tube bent to an acute angle, or a retort is used, a sort, of long-necked Florence flask, dextrously bent near the body by the glass-w'orker to an appropriate angle (hence the name retort, from retorqueo, to bend back). Condensation is effected by surrounding the lateral steam-tube wuth cold water. In large stills the steam- tube, or condensing-iuorm, is usually a metal (tin) pipe, twisted into a spiral form for the sake of compactness, and so fixed in a tub that a few' inches of one end of the pipe may pass through and closely fit a hole bored near the bottom of the tub. Cold w'ater is kept in contact w'ith the exterior of the pipe, provision being made for a continuous supply to the bottom, wdiile the w'ater heated by the con- densing steams runs off fromThe top of the column. The condenser for a flask or retort may be a simple glass tube of any size, placed within a second much w ider tube (a common long, narrow' lami>glass answers very w’ell for experimental operations), the tube being con- nected at the extremities of the w'ider by bored corks ; a stream of ZINC. 109 water passes into one end of the inclosed space (the end furthest from the retort), through a small glass tube inserted in the cork, and out at the other through a similar tube. The common (Liebig’s) form of laboratory condenser is a glass tube three-fourths of an inch wide and a yard long, surrounded by a shorter tin or zinc tube two inches in diameter, and having at each extremity a neck, through which the glass tube passes. The ends of the necks of the tin tube, and small portions of the glass tube near them, are connected by means of a strip of sheet caoutchouc carefully bound round. An aperture near the lower part of the tin tube provides for the admis- sion of a current of cold water, and a similar aperture near the top allows the escape of heated water. The inner tube may thus con- stantly be surrounded by cold water, and heated vapors passing through it be perfectly cooled and condensed. In distilling several gallons of water for analytical or medicinal purposes [Aqua Destillata, B. P. and U. S. P.), the first two or three pints should be rejected, because likely to contain ammoniacal and other volatile impurities. Rectification is the process of redistilling a distilled liquid. Rec tified s'pirit is spirit of wine thus treated. Dry or destructive distillation is distillation in which the con- densed products are directly formed by the decomposing infiuence of the heat applied to the dry or non-volatile substances in the retort or still. EXEKCISE. 184. Write from memory two or three paragraphs descriptive of distillation. ZINC. ALUMINIUM, IRON. These three elements are classed together for analytical conven ience rather than for more general analogies. ZINC. Symbol Zn. Atomic weight 65. Source. — Zinc is tolerably abundant in nature as sulphide (ZnS) or blende, and carbonate (ZnCOg) or calamine (from calamus, a reed, in allusion to the appearance of the mineral). The ores are roasted to expel sulphur, carbonic acid gas, and some impurities, and the resulting oxide distilled with charcoal, when the metal vaporizes and readily condenses. Zinc is a brittle metal, but at a temperature somewhat below 300^ F. is malleablOj and may be rolled into thin sheets. Above 400^ it is again brittle, and may then be pulverized. At 773^ F. it melts, and at a bright red heat is volatile. Uses. — Its use as a metal is familiar ; alloyed with nickel it yields german silver ; with twice its weight of copper forms common brass, and as a coating on iron (the so-called galvanized iron) greatly 10 110 THE METALLIC RADICALS. retards the formation of rust. Most of the salts of zinc are pre- pared, directly or indirectly, from the metal (Zinciim, B. P. and U. S. P.).^ Quantivalence . — The atom of zinc is bivalent, Zn". Molecular Weight , — Some remarks on this point will be made under Mercury. Reactions having (a) Sythetical and {h) Analytical Interest. (a) Synthetical Reactions. Sulphate of Zinc, Fir^t Synthetical Reaction . — Heat zinc (4 pts.) with water (20 pts.) and sulphuric acid (3 11. pts.) in a test-tube (or larger vessel) until gas ceases to be evolved ; solution of sulphate of zinc (ZnSOJ results. Filter and concentrate the solution in an evaporating dish ; on cooling, color- less, transparent, prismatic crystals of Sulphate of Zinc (ZnS 04 ,'lH 20 ) are deposited {Zinci Sulphas^ B. P. and U. S. P.). Zn^ + 2 H 2 SO, + xUfi = 2ZnSO, -f + 2 H 2 Zinc. Sulphuric Water. Sulphate of Water. Hydrogen, acid. Zinc. Zinc does not displace hydrogen from the sulphuric acid alone, nor from the water alone, yet the mixture affords hydrogen. The pro- bable explanation is that as sulphuric acid combines wuth several different quantities of w^ater to form definite hydrous compounds (H2SO4, H2O ; H2SO4, 2H2O ; etc), it is one of these that is decom- posed with elimination of hydrogen. At present we can only say that an unknowm (cc) amount of w^ater is required in the reaction. Note . — This reaction affords hydrogen and sulphate of zinc ; it also gives electricity. Of several methods of evolving hydrogen, it is the most convenient; of the two or three means of preparing sulphate of zinc it is that most commonly employed; and of the many reactions which may be utilized in the development of dynamic electricity it is at present the cheapest and most manageable. The apparatus in which the reaction is effected differs according to the requirements of the operator; if the sulphate of zinc alone is wanted, an open dish is all that is necessary, the action being, perhaps, accelerated by heat; if hydrogen, a closed vessel and delivery-tube; if electricity, square vessels called cells and certain complementary materials, forming altogether what is termed a battery. In each operation for one product the other two are commonly wasted. It would not be difficult for the operator, as a matter of amusement, to construct an apparatus in which all three products should be collected. Purification . — Impure sulphate of zinc may be purified in the same manner as impure chloride (see next reaction). ZINC. Ill Sulphate of zinc is isomorphous with sulphate of magnesium, and, like that salt, loses six-sevenths of its water of crystallization at 2120 F. Chloride of Zinc. Second Synthetical Reaction , — Dissolve zinc in hydro- chloric acid mixed with half its bulk of water ; the resulting solution contains chloride of zinc. Evaporate the liquid till no more steam escapes ; Chloride of Zinc (ZnCl2) in a* state of fusion remains, and, on cooling, is obtained as a white opaque solid {Zinci Ghloridum,, B. P. and U. S. P.). It is soluble in water, alcohol, or ether. Zn^ -f 4Hei 2ZnCl3 + 2H, Zinc. Hydrochloric Choloride Hydrogen, acid. of zinc. This reaction is analogous to that previously described. The Burnett deodorizing or disinfecting liquid is solution of chloride of zinc. Purification of Chloride or Sulphate of Zinc. — Zinc sometimes contains traces of iron or lead ; and these, like zinc, are dissolved by most acids, with formation of soluble salts ; they may be recognized in the liquids by applying the tests described hereafter to a little of the solution in a test-tube (p. 114). Should either be present in the above solution, a little chlorine water is added to the liquid till the odor of chlorine is permanent, and then the whole well shaken with some hydrate of zinc or the common official “carbonate” of zinc (really hydra to-carbonate — see next page). In this way iron is pre- cipitated as ferric hydrate, and lead as peroxide : — *2FeCl2 4- CI2 = ^Fe^Cl^ Ferrous chloride. Chlorine. Ferric chloride. + 3ZnC03 -f SH^O = Fe.fiUO + SZnCl^ + 300., Ferric Carbonate Water. Ferric hydrate. Chloride Carbonic chloride. of zinc. of zinc. acid gas. PbOL, 4- CI2 4- 2ZnC03 = PbO^ 4- 2ZnCl2 4- 200., Chloride Chlorine. Carbonate Peroxide Chloride Carbonic of lead. of zinc. of lead. of zinc. acid gas. In the British Pharmacopoeia the presence of impurities in the zinc is assumed, and the process of purification just described incor- porated with the process of preparation of Zinci Ghloridum, Liquor Zinci Chloridi, and Zinci Sulphas. In the purification of the sul- phate of zinc, the action of chlorine on any ferrous sulphate will result in the formation of ferric sulphate as well as ferric chloride : — 6FeS0, 4- Cle = 2(Fe23SOJ 4- Fe^Clg; * It will be noticed that the iron is represented, in these equations, as exerting both bivalent and trivalent activity ; this will be alluded to when iron comes under consideration. 112 THE METALLIC RADICALS. carbonate of zinc will then give chloride as well as sulphate of zinc, and thus the whole quantity of sulphate of zinc be slightly contami- nated by chloride. On evaporating and crystallizing, however, the chloride of zinc will be retained in the mother-liquor. For Liquor Zinci Chloridi, B. P., 1 pound of zinc is placed in a mixture of 44 fluidounces of hydrochloric acid and 20 of water, the mixture ultimately warmed until no more gas escapes, filtered into a bottle, chlorine water added until the liquid after shaking smells fairly of chlorine, about half an ounce or somewhat more of carbonate of zinc shaken up with the solution until a brown precipitate (of ferric hydrate or peroxide of lead, or both) appears, the whole filtered and the filtrate evaporated to 40 fluidounces. One fluidounce con- tains 366 grains of chloride of zinc. If there is reason to believe that neither iron nor lead is present in the zinc, the treatment of chlorine, water, and carbonate of zinc may be omitted. The Liquor Zinci Chloridi^ U. S. P., is prepared by a somewhat similar process, nitric acid, however, is used instead of chlorine water ; the solution con- tains 375 grains of chloride of zinc in one fluidounce. Carbonate of Zinc. Third Synthetical Beaction. — To solution of any given quantity of sulphate of zinc in twice its weight of water (in a test-tube, evaporating basin, or other large or small vessel), add about an equal quantity of carbonate of so- dium, also dissolved in twice its weight of water, and boil; the resulting white precipitate is so-called Carbonate of Zinc {Zinci Carhonas^ B. P., Zinci Carhonas Precipitata^ U, S. P.), a mixture of carbonate (ZnCO^) and h3^drate (Zn 2 HO), in the proportion of one molecule of the former and two of the latter, together with a molecule of water (HgO). It maybe washed, drained, and dried in the usual manner. It is used in the arts under the name of zinc- white^ and frequently in medicine in the form of ointment ( Geratum Zinci Carhonatis^ U. S. P.). 3 ZnSO, + 2 H ,0 + 3^XC03 = ZnC03,2ZnII.,0, -f- 2 CO., Sulphate Water. Carbonate Official carbonate Carbonic of zinc. of .sodium. of zinc. acid gas. + 3 Na.,SO, Sulphate of sodium. Acetate of Zinc. Fourth Syjithetical Beaction, — Collect in a filter the pre- cipitate obtained in the last reaction, wash with distilled water, and dissolve a portion in strong acetic acid; the resulting solution contains acetate of zinc (Zn2C.^H30.^), and, on evaporating, and setting aside for a day, 3uelds ZINC. 113 lamellar pearly crystals (Zn2C2H30^,2H^0). This is the process for Zinci Acetas, B. P. ZnC03,2ZnH202 + 6HC2H3O2 = 3(Zn2C2H302) + 5 H ,0 Official carbonate Acetic Acetate of zinc. Water, of zinc. acid. + CO, Carbonic acid gas. The U. S. P. process consists in digesting oxide of zinc in acetic acid, heating the mixture to boiling point, filter- ing while hot, and setting aside the clear solution to crys- tallize. Oxide of Zinc. Fifth Synthetical Reaction. — Dry the remainder of the precipitated carbonate (bj^ placing the open filter on a plate over a dish of water kept boiling), and then heat it in a small crucible till it ceases to effervesce on the addi- tion of water and acid to trial samples taken out of the crucible from time to time; the product is Oxide of Zinc {Zinci Oxidum., 1 ^. P. and U. S. P.), much used in the form of ointment ( Unguentum Zinci^ B. P.,and Unguentum Zinci Oxidi, U. S. P.). ZnC03, 2ZnH202 = 3ZnO + + CO^ Official carbonate Oxide of Water. Carbonic of zinc. zinc. acid gas. Note . — This oxide is yellow while hot, and of a very pale yellow or slight buff tint when cold, not actually white like the oxide pre- pared by the combustion of zinc in air. The latter variety occurs in commerce under the name of Hubbuck’s oxide of zinc. Its prepara- tion can only be practically accomplished on the large scale, but the chief features of the action may be observed by heating a piece of zinc in a small porcelain crucible till it burns ; flocks escape from the crucible, float about in the air, and slowly fall. These are the old Flores Zinci, Lana Fhilosophica, or Nihilum Album, Valerianate of Zinc. Sixth Synthetical Reaction. — Valerianate of Zinc (Zn2C5 H9O2) {Zinci Valerianas,, B. P.) is prepared by mixing strong solutions of sulphate of zinc and valerianate of sodium, cooling, separating the white pearly crystalline matter, evaporating at 200° to a low bulk, cooling, again separating the lamellar crystals, washing the whole pro- duct with a small quantity of cold distilled water, drain- ing and drying by exposure to air at ordinarj^ tempera- 114 THE METALLIC RADICALS. tures. Valerianate of zinc is soluble in ether, alcohol, or hot water. ZnSO, + 2NaC,H,0, = Na,SO, + Zn2C3H,0, Sulphate Valerianate of Sulphate of Valerianate of zinc. sodium. sodium. of zinc. jSfote . — The compounds of zinc described in the above six reac- tions are the only ones mentioned in the British Pharmacopoeia ; the processes are also those of that work. Sulphide and Hydrate of Zinc are mentioned in the following analytical paragraphs. The formula of Sulphite of Zinc is ZnS 03,31120. (h) Reactions having Analytical Interest (Tests). First Analytical Reaction. — To solution of a zinc salt (sulphate for example) in a test-tube, add solution of sul- ph^^drate of ammonium (NH^HS) ; white sulphide of zinc (Z'nS) is precipitated, insoluble in acetic, but soluble in the stronger acids. JSfote . — This is the only white sulphide that will be met with. Its formation, on the addition of the sulphydrate of ammonium, is there- fore highly characteristic of zinc. If the zinc salt contains iron or lead as impurities, the precipitate will have a dark appearance, the sulphides of those metals being black. Hydrate of aluminium, which is also white and precipitated by sulphydrate of ammonium, is the only substance sulphide of zinc is likely to be mistaken for, and vice vers i ; but, as will be seen immediately, there are good means of distinguishing these from each other. Second Analytical Reaction. — To solution of a zinc salt add solution of ammonia ; white hydrate of zinc (Zn2H0) is precipitated. Add excess of ammonia ; the preci[)itate is redissolved. This reaction at once distinguishes a zinc salt from an aluminium salt, hydrate of aluminium being insoluble in ammonia. Other Analytical Reactions. — The fixed alkali-hydrates afford a similar reaction to that just mentioned, the hydrate of zinc redissolving if the alkali is free from carbonate. Carbonate of ammonium yields a white precipitate of car- bonate and hydrate, soluble in excess. The fixed alka- line carbonates give a similar precipitate, which is not redissolved if the mixed solution and precipitate be well boiled. Ferrocyanide of potassium precipitates white ferrocyanide of zinc (Zn.^FeCyg). Sulphate of magnesium, which is isomorphous with and indistinguishable in appearance from sulphate of zinc, is not precipitated from its solutions either by ferrocyanide of potassium or sulphydrate of ammonium. ALUMINIUM. 115 Antidotes . — There are no efficient chemical means of counteract ing- the poisonous effects of zinc. Large doses, fortunately, act as . powerful emetics. If vomiting has not occurred, or apparently to ,/ an insufficient extent, solution of carbonate of sodium (common wash- ing salt) immediately followed by white of egg and demulcents may be administered. QUESTIONS AND EXERCISES. 185. Give the sources and uses of metallic zinc. 186. Explain by a diagram what occurs when zinc is dissolved in dilute sulphuric acid. 187. How may solutions of Chloride of Sulphate of Zinc be puri- fied from salts of iron ? Give equations descriptive of the reactions. 188. State the formula of Carbonate of Zinc, and illustrate by a diagram the reaction which takes place in its production. 189. Give an equation showing the formation of Acetate of Zinc. 190. In what respect does Oxide of Zinc, resulting from the igni- tion of the carbonate, differ from that produced during the combus- tion of the metal ? 191. How is Valerianate of Zinc prepared? 192. What are the properties of Valerianate of Zinc. 193. Name the more important tests for zinc. 194. How would you distinguish, chemically, between solutions of Sulphate of Zinc and Alum ? 195. Describe the treatment in cases of poisoning by salts of zinc. 196. Give reactions distinguishing Sulphate of Zinc from Sulphate of Magnesium. ALUMINIUM. Symbol Al. Atomic weight 27.5. Note . — In the formulae of aluminium salts, it will be observed that to one atom of metal there are three atoms of other univalent radi- cals ; hence, apparently, the atom of aluminium is trivalent, Al'". But possibly it is quadrivalent ; for one molecule of aluminium com- pounds includes two atoms of the metal, three-fourths only of whose power may be supposed to be exerted in retaining the other constitu- ents of the molecule, the remaining fourth enabling the aluminium atoms themselves to keep together. This is graphically shown in the following formula of chloride of aluminium (Al^Clg) from Frank- land’s “ Lecture Notes for Chemical Students," which represents each Cl Cl Cl-Al- Al-Cl I I Cl Cl aluminium atom as a body having four arms or bonds, three of which are engaged in grasping the arms of univalent chlorine atoms, while 116 THE METALLIC RADICALS. the fourth grasps the corresponding arm of its brother aluminium atom. Such graphic formulae, as they are called, are useful in facilitating the acquirement of hypotheses regarding the constitution of chemical substances, especially if the error be avoided of suppos- ing that they are pictures either of the position or absolute power of atoms in a molecule, or indeed, the true representation of a mole- cule at all ; for on this point man knows little or nothing. Source . — Aluminium is very abundant in nature, chiefly as sili- cate, in clays, slate, marl, granite, basalt, and a large number of minerals. The sapphire and ruby are almost pure oxide of aluminium. The metal is obtained from the double chloride of aluminium and sodium, by the action of metallic sodium, the source of the chloride being the miueral bauxite. Aluminium-bronze is an alloy of ten parts of aluminium with ninety of copper. Alum [Alumen, B. P. and U. S. P.), a double sulphate of alumi- nium and ammonium (Al 23 SO^, Am2S04, 24H2O), may be obtained from aluminous schist (from scliisios, divided) a sort of pyri- tous slate or shale, by exposure to air ; oxidation and chemical change produce sulphate of aluminium, sulphate of iron, and silica, from the silicate of aluminium and bisulphide of iron (iron pyrites) originally present in the shale. The sulphate of aluminium and sulphate of iron are dissolved out of the mass by water, and sulphate or chloride of ammonium added ; on concentrating the liquid, alum cyrstallizes out, while the more soluble iron salt remains in the mother-liquor. Alum is also prepared by directly decomposing the silicate of aluminium in the calcined shale of the coal-measures by hot sulphuric acid, ammonia being added from time to time until a solution strong enough to crystallize is obtained. The liquid well agitated during cooling deposits alum-flour, which is afterwards recrystallized. Alums . — There are several alums, iron or chromium replacing aluminium, and potassium or sodium taking the place of ammonium, all crystallizing in an eight-sided form, the octahedron — a sort of double pyramid. These are, apparently, alike in chemical consti- tution, and their general formula (M = either metal) is M'"2flS04, M'2S04, 24H2O. The alum of the manufacturer commonly occurs in colorless, transparent, octahedral crystals, massed in lumps, which are roughly broken up for trade purposes, but still exhibit the faces of octahedra. Sulphate of Aluminium (AI23SO4, 9H2O), or Alum Cake, pre- pared from natural silicates in the manner just described, is a com- mon article of trade, serving most of the manufacturing purposes for which alum was formerly employed. In the United States Pharma- copoeia {Aluminii Sulphas) it is directed to be made by dissolving hydrate of aluminium in diluted sulphuric acid with subsequent re- moval of water by evaporation. AI26HO + 3H2SO4 = AI23SO4 + 6H2O. The hydrate of aluminium is to be prepared by the addition of solu- tion of alum to solution of carbonate of sodium, the precipitated hydrate being collected on a filter and well washed. ALUMINIUM. in A1,3S0„ Am, SO, 4- 3Na,C03 + 3H,0 = A1,6H0 + Am,SO, + 3Na,S0, + 300,. Preparation of Alum. — Prepare alum by heating a small quan- tity of powdered pipeclay (silicate of aluminium) with about twice its weight of sulphuric acid for some time, dissolving out the result- ing sulphate of aluminium and excess of sulphuric acid by water, and adding only ammonia to the clear-filtered solution until, after well stirring, the excess of acid is neutralized. (If too much ammonia be added the hydrate of aluminium precipitated when the ammonia is first poured in will not be redissolved on well mixing the whole. Perhaps the readiest indication of neutrality in this and similar cases is the presence of a little precipitate after stirring and warming the mixture.) On evaporating the clear solution, crystals of alum are obtained. The Ammonio ferric Alum of American pharmacy [Ferri et Ammonii Sulphas, U. S. P.) is made by adding sulphate of ammo- nium to a hot solution of persulphate of iron, and setting the liquid aside to crystallize. It forms pale violet octahedral crystals, ex- pressed by the formula Fe43SO„ (NH,)2S04, 2411,0. Aluminii et Potassii Sulphas (U. S. P.) is potassium alum, the sulphate of alu- minium and potassium (Al^SSO,, K2SO4, 24H2O). Dried Alum [Alumen Exsiccatum, B. P. and U. S. P.) is alum from which the water of crystallization has been expelled by heat, the temperature not exceeding 400°. By calculation from the mole- cular weight of alum, it will be found that the salt contains between 47 and 48 per cent, of water. At temperatures above 400^ alum is decomposed, sulphate of ammonium and sulphuric anhydride escap- ing, and pure alumina (AI2O3) remaining. Dried alum rapidly reabsorbs water from the atmosphere. It is almost useless as a medicinal preparation. Roche alum, or Rode alum {roche, French, rock), is the name of an impure native variety of alum containing iron. The article sold under this name is an artificial mixture of common alum with oxide of iron. Reactions having Analytical Interest. First Analytical Reaction, — To a solution of an aluminium salt (alum, for example, which contains sulphate of alumi- nium) add sulphj'drate of ammonium (NH^HS); a gelati- nous white precipitate of hydrate of aluminium falls : — Al, 3 SO, -f 6AmHS + 6H2O = Al,6HO + 3 Am^SO, + 6H^S. Second Analytical Reaction. — To solution of alum add ammonia, NH,HO ; hydrate of aluminium falls: add excess of ammonia; the precipitate is insoluble. Principle of Dyeing by help of Mordants. — The precipi- tated hydrate of aluminium, or alumina, has great affinity for vegetable coloring-matters, and also for the fibre of 118 THE METALLIC RADICALS. cloth. Once more perform the above experiment, but be- fore adding the ammonia introduce some decoction of log- wood, solution of cochineal, or other similar colored liquid, into the test-tube. Add now the ammonia, and set the tube aside for the alumina to fall ; the latter takes down with it all the coloring principle. In dye-works the fabrics are passed through liquids holding the alumina but weakly in solution, and then through the coloring solutions ; from the first bath the fibres abstract alumina, and from the second the alumina abstracts coloring matter. Some other metallic hydrates, notably those of tin and iron, resemble alumina in this property ; the}’ are all termed mordants (from mordens^ biting) ; the substances they form with coloring-matters have the name of lakes. Third Analytical Reaction , — To the alum add solution of potash; again hydrate of aluminium falls. Add excess of potash, and agitate ; the precipitate dissolves. Alumina may be precipitated from this solution by neu- tralizing the potash with hydrochloric acid, and adding ammonia until, after shaking, the mixture has an ammoni- acal smell, or by adding solution of chloride of ammonium to the potash liquid. But the former way is the better ; for it is difficult to know when a sufficiency of the chloride of ammonium has been poured in, whereas reaction with blue and red litmus-paper at once enables the operator to know when excess of hydrochloric acid or ammonia has been added. Alkaline carbonates, phosphates, arseniates, and salts of other aci- dulous radicals also decompose solutions of aluminium salts and pro- duce insoluble compounds of that metal, with the several acidulous radicals (except the carbonic), but the resulting precipitates are of no special interest. QUESTIONS AND EXERCISES. 197. What is there remarkable about the quanti valence of alumi- nium? 198. Practically what is the quantivalence of the atom of alumi- nium ? 199. Enumerate the chief natural compounds of aluminium. 200. Write down a formula which will represent either of the Alum’s. 201. Which alum is official, and commonly employed in the arts ? 202. State the source, and explain the formation of alum. 203. What is the crystalline form of alum ? Work a sum showing IRON. 119 how much Dried Alum is theoretically producible from 100 pounds of alum ? Ans. 52 lbs. 6 ozs. 204. Show by figures how ordinary ammonium alum is capable of yielding 11.356 per cent, of alumina. 205. Why are aluminium compounds used in dyeing ? 206. How are salts of aluminium analytically distinguished from those of zinc ? IRON. Symbol Fe. Atomic weight 56. Sources . — Compounds of iron are very abundant in nature. Mag- netic Iron Ore, or Loadstone [Lodestone or Leadstone, from the Saxon Icedan, to lead, in allusion to its use, or rather of magnets made from it, in navigation), is the chief ore from which Swedish iron is made ; it is a mixture of ferrous and ferric oxide (Fe0,Fe203). Much of the Russian iron is made from Specidar Iron Ore (from speculum, a mirror, in allusion to the lustrous nature of the crystals of this mineral). This and Red Haematite (from al^a, liaima, blood, so named from the color of its streak) an ore raised in Lancashire, are composed of ferric oxide only (Fe203). Brown Haematite, an oxy- hydrate, is the source of much of the French iron. Spathic Iron Ore (from spatha, a slice, in allusion to the lamellar structure of the ore) is a ferrous carbonate (FeCOg). An impure ferrous carbonate forms the Clay Ironstone, whence most of the English iron is derived. The chief Scotch ore is also an impure carbonate, containing much bituminous matter ; it is known as Black Band. Iron Pyrites (from Ttvp, pur, fire, in allusion to the production of sparks when sharply struck) (FeS2) is a yellow lustrous mineral, of use only for its sul- phur. Ferrous carbonate (FeCOy), chloride (FeCl2,4H2^)5 phate (FeS04,7H20) sometimes occur in springs, the water of which is hence termed chalybeate [chalybs, steel). Process. — Iron is obtained from its ores by processes of roasting, and reduction of the resulting impure oxide with coal or charcoal in the presence of chalk, the latter uniting with the sand, clay, etc., to form a fusible slag. The cast iron thus produced is converted into ivrought iron [Ferrum, U. S. P) by burning out the 4 or 5 per cent, of carbon, silicon, and other impurities present, by oxidation in a furnace, an operation which is termed puddling. Steel is wrought iron impregnated with from one to two per cent, of carbon by strongly heating in charcoal. The official variety of the metal [Ferrum, B. P.), the condition in which it is most easily employed for conversion into its compounds, is “ wrought iron in the form of wire or nails free from oxide.” In the form of a fine powder (see 17 Reac.) metallic iron is employed as a medicine. Properties. — The specific gravity of pure iron is 7.844, of the best bar iron 7.7 ; its color is bluish-white or gray. Bar iron requires the highest heat of a wind-furnace for fusion, but below that temperature assumes a pasty consistence, and in that state two pieces may be joined or welded (Germ, wellen, to join) by the pressure of blows from a hammer. A little sand thrown on to the hot metal facilitates 120 THE METALLIC RADICALS. this operation by forming with the superficial oxide of iron a fusible slag, which is dispersed by the blows : the purely metallic surfaces are thus better enabled to come into thorough contact and enter into perfect union. Iron is highly ductile, and of all common metals pos- sesses the greatest amount of tenacity. At a high temperature it burns in the air, forming oxide of iron. Rust of iron is chiefly red oxide of iron, with a little ferrous oxide and carbonate ; it is pro- duced by action of the moist carbonic acid of the air and subsequent oxidation. Steam passed over scrap iron heated to redness gives hydrogen gas and black oxide of iron. Quantivalence. — Iron combines with other elements and radicals in two proportions ; those salts in which the atom of iron appears to possess inferior affinities (in which the other radicals are in the less amount) are termed ferrous, the higher being ferric salts. In the former the iron exerts bivalent (Fe"), in the latter trivalent activity (Fe'" or Fe./i). The atom of iron is also sometimes considered to be sexivalent, on account of the analogy of its compounds with those of chromium, wffiich is sexivalent, if the formula of its fluoride (CrFg) be correct, and because the composition oi ferrate of potassium (KjFeO^), a deep-purple salt obtained on passing chlorine through a concentrated solution of potash in which fresh ferric hydrate is suspended, is best explained on the assumption of the sexivalence of its iron. Why the quantivalence of the atom of iron should vary is not at present known. The Nomenclature of Iron Salts. — For educational and descrip- tive purposes the two classes of iron compounds are very conveniently spoken of as ferrous and ferric, the syllable '^ferr'" common to all indicating their allied ferruginous character, the syllable ous and ic indicating the lower and higher class respectively — functions fulfilled by these two syllables in other similar cases (sulphurous and sulphu- ric, mercurous and mercuric). Officially the iron s^lts are known by other names, thus. Sulphate of Iron (Ferri Sulphas), and Phos- phate of Iron [Ferri Phosphas), names which are chemically inex- plicit, for there are two sulphates, and two phosphates, and the terms do not define which salt is intended. Consistency and uniformity would demand that the names Ferrous Sulphate, Ferrous Phosphate, or similar terms should be employed. Practically, however, the old names cause no confusion, inasmuch as only one sulphate, phosphate, etc., are used in medicine ; moreover, the higher salts usually have the prefix per attached (as persulphate, perchloride). These names are already well known, can be easily rendered in Latin, and then admit of simple abbreviations and adaptations such as are employed ' in prescriptions, advantages not possessed by the more rational terms. While, therefore, the comprehension of the chemistry of iron is ren- dered simple and intelligible by the use of the terms ferrous and ferric, the employment of older and less definite names may very well be continued in pharmacy as being practically more convenient. IRON. 121 Reactions having (a) Synthetical and (b) Analytical Interest. (a) Synthetical Reactions. FERROUS SALTS. Green Sulphate of Iron. Ferrous Sulphate. First Synthetical Reaction, — Place iron (small tacks) in sulphuric acid diluted with eight times its bulk of water (in a test-tube, basin, or other vessel of any required size), accelerating the action by heat until effervescence ceases. Fe, + 2H,SO, = 2FeSO, -f 2H., Iron. Sulphuric Ferrous Hydrogen, acid. sulphate. The solution contains what is generally known as Sul- phate of Iron, that is. Ferrous Sulphate, the lower of the two sulphates, and will yield crystals of that substance (FeS0^,7Il20) {Ferri Sulphas,^ B. P. and U. S. P.) on cool- ing or on further evaporation; or if the hot concentrated solution be poured into alcohol, the mixture being well stirred, the sulphate is at once thrown down in minute crystals {Ferri Sulphas Granulata^ B. P.). At a tempera- ture of 400° F. ferrous sulphate loses six-sevenths of its water, and becomes the Ferri Sulphas Fxsiccata^ B. P. Other Sources of Ferrous Sulphate . — In the laboratory, ferrous sulphate is often obtained as a by-product in making sulphuretted hydrogen, FeS + H^SO, = H^S -f FeSO,. In manufactories it occurs as a by-product in the decomposition of aluminous shale, as already noticed (p. 116 ). Ten grains of granulated sulphate of iron dissolved in one ounce of water constitutes “Solution of Sulphate of Iron,’^ B. P. “ The solution should be recently prepared.” Notes. — Ferrous sulphate is sometimes termed green vitriol. Vitriol (from vitrum, glass) was originally the name of any trans- parent crystalline substance, but afterwards restricted to the sul- phates of zinc, iron, and copper, which were, and still are, occasion- ally known as white, green, and blue vitriol. Copperas (probably originally Copper-rust, a term applied to verdigris and other green incrustations of copper) is another name for this sulphate of iron, sometimes distinguished as green copperas, sulphate of copper being blue copperas. Solid sulphate of iron is a constituent of Pilula Aloes et Ferri, B. P. Ferrous sulphate, when exposed to the air, gradually turns brown 11 122 THE METALLIC RADICALS. through absorption of oxygen, ferric oxysulphate (Fe202S04) being formed. The latter is not completely dissolved by water, owing to the formation of a still lower insoluble oxysalt (Fe^O-SO^) and solu- ble ferric sulphate 5(Fe202S04) = Fe405S04 -h 3 (Fe 23 S 04 ). Iron heated with undiluted sulphuric acid gives sulphurous acid gas and ferrous sulphate : — Fe2 + 4H2SO4 = SO2 + FeSO^ + 2H2O. Carbonate of Iron. Ferrous Carbonate. Second Synthetical Reaction . — To solution of ferrous sulphate, boiling, in a test-tube, add a solution of carbonate of ammonium (Am2C03, etc.) in recently boiled water ; a white precipitate of ferrous carbonate (FeCOg) is thrown down, rapidly becoming light green, bluish-green, and, after a long time, red, through absorption of oxygen, evolution of carbonic acid gas, and formation of ferric oxyhydrate. FeSO^ + Am2C03 = FeCOg + Am2S04 Ferrous Carbonate of Ferrous Sulphate of sulphate. ammonium. carbonate. ammonium. Saccharated Carbonate of Iron. — The above precipitate, rapidly washed with hot well-boiled distilled water, and the moist powder mixed with sugar and quickly dried — in short, all possible precau- tions taken to avoid exposure to air — forms the saccharated carbo- nate of iron [Ferri Carhonas Saccharata, B. P.). The official proportions are two ounces of the sulphate and one ounce and a quarter of the carbonate, each dissolved in half a gallon of hot water ; the solutions are mixed and set aside in a deep well- covered pan, the supernatant liquid poured off when the precipitate has subsided, the pan again filled up with boiling water, the liquid once more poured away, the precipitate transferred to a calico filter, drained, gently pressed, and while still somewhat moist rubbed in a mortar with one ounce of sugar, and finally dried over a water-bath. Carbonate of Iron, mixed with a fourth its w^eight of Confection of Roses (Honey and Sugar, U. S. P.), forms the Pilula Ferri Car- honatis, B. P. and U. S. P. Notes. — The Subcarbonate of Iron [Ferri Subcarbonas, U. S. P.) is precipitated on mixing solutions of sulphate of iron and carbonate of sodium. On washing and drying it is converted into reddish- brown oxyhydrate of iron, water being absorbed and carbonic acid gas being eliminated. This oxyhydrate of iron is best made by pre- cipitating solution of persulphate of iron by solution of soda, and washing and drying the product (see page 127 ). Saccharated ferrous carbonate is said to be more easily dissolved in the stomach than any other iron preparation. It is so unstable and prone to oxidation, that it must be washed in w^atcr containing no dissolved air and mixed with the sugar (which protects it from oxidation) as quickly as possible. In making the official compound mixture of iron [Mistura Ferri Composita. B. P. and U. S. P.), IRON. 123 Griffith’s mixture,” the. various ingredients, including the carbonate of potassium, should be placed in a bottle of the required size, space being left for the crystals or solution of ferrous sulphate, which should be added last, the bottle immediately filled up with rose- water, and securely corked ; oxidation is thus prevented to the greatest possible extent. Pihdce Ferri Compositce, U. S. P., is made from myrrh, carbonate of sodium, sulphate of iron and syrup ; carbonate of iron is gradually formed. FeSO, + K,C 03 = FeC 03 + K^SO^ Ferrous Carbonate of Ferrous Sulphate of sulphate. potassium. carbonate. potassium. Arseniate of Iron. Ferrous Arseniate. Third Synthetical Reaction^ by which the lower arseniate of iron, ferrous arseniate {Ferri Arsenias, B. P.) (Fe 3 2J^ sOJ, partiall}’ oxidized, is formed. This will be noticed again under Arsenicum. Phosphate of Iron. Ferrous Phosphate. Fourth Synthetical Reaction. — To solution of ferrous sulphate in a test-tube add a little solution of acetate of sodium, then solution of phosphate of sodium ; the lower phosphate of iron, ferrous phosphate (Fe 32 PO^), is precipi- tated {Ferri Phosphas^ B. P. and U. S. P.). 3FeSO, -f 2NaJIPO, + Ferrous Phosphate of Acetate of sulphate. sodium. sodium. = Fe 32 PO, + 3Na,SO, + 2 HC,H 30 , Ferrous Sulphate of Acetic acid, phosphate. sodium. Officially, solutions of 3 ounces of sulphate of iron in a quart of water, and 2^ ounces of phosphate and 1 of acetate of sodium in another quart of water, are well mixed, filtered, the precipitate well washed, and, to prevent oxidation as much as possible, dried at a temperature not exceeding 120^ F. These proportions will be found to accord with the molecular weights of the crystalline salts, multi- plied as indicated in the foregoing equation. 3 (FeS 04 , 7H^O)=834; 2 (Na,HP 04 , 12H20)=716; 2 (Na 02 H 302 , 3H20)=272. The use of the acetate of sodium (not mentioned in the U. S. P. formula) is to insure the occurrence of acetic acid in the solution, where otherwise would be free sulphuric acid. Sulphuric acid is a solvent of ferrous phosphate ; acetic acid is not. It is impossible to prevent the separation of sulphuric acid, if only ferrous sulphate and phosphate of sodium be employed. Ferrous phosphate is white, but soon oxidizes and becomes slate-blue. The above reaction also occurs in making Syrupus Ferri Plios- phatis, B. P. The precipitate should be well washed, or red ferric acetate may be developed after a time. 124 THE METALLIC RADICALS. Sulphide of Iron. Ferrous Sulphide. Fifth Synthetical Reaction , — In a gas- or spirit-flame strongly heat about twice its weight of iron filings in a test-tute'(<^ in an earthen crucible in a furnace) ; ferrous sulphide (iTeS) is formed. When cold, add water to a small portion, and then a few drops of sulphuric acid ; sulphuretted hydrogen gas (H^S), known by its odor, is evolved. FeS + H,SO, = FeSO, + H^S. Sticks of sulphur pressed against a white-hot bar of cast iron give the purest form of ferrous sulphide. The liquid sulphide thus formed is allowed to drop into a vessel of water (Sulphide of Iron, B. P. ; Ferri Sulphuretum, U. S. P.). Green Iodide of Iron. Ferrous Iodide. . Sixth Synthetical Reaction , — Place a piece of iodine, about the size of a pea, in a test-tube with a small quantity of water, and add a few^ iron filings, small nails, or iron wire. On gently warming, or merely shaking if longer time be allow^ed, the iodine disappears, and, on filtering, a clear light green solution of iodide of iron (Fel J is obtained. The official Ferri lodidum is formed by gently warming a mix- ture of 3 parts of iodine, of fine iron wire, and 12 of distilled water in an iron vessel. When combination is nearly complete (as shown by indications of a sea-green tint), boil for a short time until the whiteness of the froth proves that the iodine has entirely disap- peared. The solution is then filtered and evaporated in a clean bright iron saucepan, ladle, or dish until a drop taken out on the end of an iron wire stirrer solidifies on cooling. The liquid is poured out on a clean smooth slab, broken up and preserved in a glass-stoppered bottle. Solid iodide of iron has a crystalline fracture, is “ green with a tinge of brown ; inodorous, deliquescent, and almost entirely soluble in water, forming a slightly green solution which gradually deposits a colored sediment and acquires a red color.” The solid iodide contains about 18 per cent, of water of crystalliza- tion, and a little oxide of iron. It is deliquescent and liable to absorb oxygen from the air with formation of insoluble ferric oxyiodide or hydrato-iodide. Iodide of iron thus spoilt may be purified by re-solu- tion in water, addition of a little more iodine and some iron, warming, filtering, and evaporating as before. Ferrous bromide (FeBr.,), occasionally used in medicine, could be made, as might be expected, in the same way as the iodide. IRON. 125 FERRIC SALTS. Anhydrous Perchloride of Iron. Ferric Chloride. Seventh Synthetical Reaction — Pass chlorine (generated as usual, from black oxide of manganese and hydrochloric acid in a flask) through sulphuric acid contained in a small bottle, and thence by the ordinary narrow glass tubing to the bottom of a test-tube containing twenty or thirty small iron tacks (or a Florence flask containing 2 or 3 ounces of iron tacks), the latter kept hot by a gas-flame ; the higher chloride of iron, ferric chloride, or the perchloride* of iron (Fe 2 Clg) is formed and condenses in the upper part of the tube or flask aa a mass of small dark iridescent crystals. When a tolerably thick crust of the salt is formed, break off the part of the glass containing it, being careful that the remaining corroded tacks are excluded, and place it in^ ten or twenty times its weight of water ; the resulting solu- tion, poured off* from any pieces of glass, is a pure neutral solution of hydrous ferric chloride, and will be serviceable in performing analytical reactions. Precaution , — The above experiment must be conducted in the open air, or in a cupboard having a draught outwards. Anhydrous Ferrous Chloride . — In breaking up the tube, small scales of a light buff color will be observed adhering to the nails ; they are crystals of ferrous chloride (FeCd.,)* Note . — Solution of ferric chloride evolves some hydrochloric acid on boiling, while a darker- colored solution of ferric oxychloride remains. Green Chloride of Iron. Hydrous ferrous Chloride. Solution of Hydrous Ferric Chloride. Eighth Synthetical Reaction, — Dissolve iron tacks, in a test-tube, in hydrochloric acid ; hydrogen escapes, and the solution on cooling, or on evaporation and cooling, de- posits cry stallized ferrous chloride (FeCl2,4H20), Through a portion of the solution of ferrous chloride pass chlorine gas ; the ferrous chloride becomes ferric chloride* The excess of chlorine dissolved by the liquid in this experiment may be removed by ebullition ; but the ferric chloride is slightly de- * The prefixes per and hyper usedi here and elsewhere are from yTrep, hyper^ over and above, and simply mean “ the highest” of several. Thus perchloride, the highest chloride, 11 * 126 THE METALLIC RADICALS. composed at the same time, for the reason just stated. The free chlorine may also be carried off* by passing a current of air through the liquid for some time. Hydrous Ferric Chloride (another process). Ninth Synthetical Reaction . — To another portion of the solution of ferrous chloride, in a test-tube, add a little more hydrochloric acid ; heat the liquid, and continue to drop in nitric acid until the black color it first produces disappears ; the resulting reddish-brown liquid is also solu- tion of ferric chloride. 6FeCT, -f 2HNO3 + eilCl = SFe.Clg + 2 NO -f mfl. Ferrous Nitric Hydrochloric Ferric Nitric Water. chloride. acid. acid. chloride. oxide. The black color is due to solution of nitric oxide gas (NO) in a portion of the ferrous salt ; it is decomposed by heat. This is the process for producing the Liquor Ferri Perchloridi Fortior, B. P., 2 ounces of iron, 12 fluidounces of hydrochloric acid, 9 fluidrachms of nitric acid, and 8 ounces of water being employed, and the product boiled down to 10 fluidounces. Practically it is impossible so to apportion the acids that a solution shall result con- taining neither excess of acid nor of metal, nor contain ferric nitrate. For most medicinal purposes, however, solution of perchloride of iron containing hydrochloric acid is said to be unobjectionable. The Liquor Ferri Chloridi, U. S. P., is a similar solution, but not quite so strong. Diluted with 3 volumes of water this strong solution gives the Liquor Ferri Perchloridi, B. P. — or with 3 volumes of rectified spirit the Tinctura Ferri Perchloi'idi, B. P. The Tinctura Ferri Chloridi, U. S. P., is a similar solution. Note. — The spirit in the tincture is unnecessary, useless, and dele- terious ; for it acts neither as a special solvent nor as a preservative, the offices usually performed by alcohol ( Tincturce et Sued, B. P. and U. S. P.) ; but, unless the liquid contain excess of acid, decom- poses the ferric chloride and causes the tbrmation of an insoluble oxychloride of iron. Even if the tincture be acid, it slowly loses color, ferrous chloride and chlorinated ethereal bodies being formed. A Liquor, of similar strength, is doubtless destined to displace the tincture altogether. Solution of ferric chloride evaporated yields a mass of yellow crys- tals [Ferri Chloridum, U. S. P:) containing Fe2Clg,121l20, or, rarely, red crystals having the formula Fe2Clg,5rf20. An old method of making solution of ferric chloride is to dissolve ferric oxide or hydrate in hydrochloric acid ; but from the varying character of trade specimens of the ingredients, the liquid is more likely to con- tain excess or deficiency of iron than the proper proportion. IRON. 12T Persulphate of Iron. Ferric Sulphate. Tenth Synthetical Reaction, — Dissolve about three-quar- ters of an ounce of ferrous sulphate and a sixth of its weight of sulphuric acid in an ounce and a half of water in an evaporating dish, heat the mixture and drop in nitric acid until the black color it first produces disappears ; the resulting liquid, when made of a certain prescribed strength, is the solution of ferric sulphate, or higher sulphate, “ So- lution of Persulphate of Iron’^ of the British Pharmaco- poeia, a heavy dark-red liquid, sp. gr. 1.441. The Liquor Ferri Tersulphatis,, TJ. S. P., is the same preparation, but slightly stronger (sp.gr. 1.320). Liquor Ferri Suhsulphatis,, U. S. P. (MonsePs solution), is a similar fluid, made with less acids, probablj^ containing, therefore, ferric oxy sul- phate and ferric oxynitrate (sp. gr. 1.552). 6FeSO, + 3H,SO, + 2HNO3 = 3(Fe,3SOJ + 2NO + 4Hp. Ferrous Sulphuric Nitric Ferric Nitric Water, sulphate. acid. acid. sulphate. oxide. The black color, as in the previous reaction, is due to a compound of ferrous salt with nitric oxide (2FeS0^4-N0). Note . — In all the reactions in which iron passes from ferrous to ferric condition the element assumes different properties, the chief being an alteration frorh bivalent to trivalent activity. Acetate of Iron. Ferric Acetate. Eleventh Synthetical Reaction, — To a strong solution of ferric sulphate (from which free nitric acid has been re- moved by evaporating to dryness and redissolving in water) add an alcoholic solution of acetate of potassium (KC^H^ O.J, and well shake the mixture ; a crystalline precipitate of sulphate of potassium (K2SO4) falls, and ferric acetate (Fe^GCgS.^Og) remains in solution, forming, when filtered, and of definite strength, the Tinctura Ferri AcetaHs.^ B. P. The preparation is unstable. Fe,3SO, + + Fe,6C2H302 Ferric Acetate of Sulphate of Ferric sulphate. potassium. potassium. acetate. The official proportions are 2^ fluidounces of “ Solution of Per- sulphate of Iron” with 8 fluidounces of rectified spirit, mixed with a solution of 2 ounces of acetate of potassium in 10 fluidounces of spirit, the whole well shaken frequently during an hour, filtered, and the precipitated sulphate of potassium washed by pouring on spirit until the filtrate measures I pint. A solution four times this strength, made from ferric hydrate and glacial acetic acid, is stable.: it is di- luted with spirit as wanted ( J. Deane and T. Jeaffreson). 128 w THE METALLIC RADICALS. Perhydrate of Iron. Ferric hydrate. Twelfth Synthetical Reaction. — Pour a portion of the solution of ferric sulphate into excess of solution of soda (ammonia, U. S. P.) ; moist ferric hydrate is precipitated {Ferri Peroxidum Hiimidum^ B. P., Ferri Oxidum Hydra- tun^ U. 8. P.). Fe^SSO, + 6NaHO = Fe.^GHO + 3Na,SO, Ferric Soda. Ferric Sulphate sulphate. hydrate. of sodium. Either of the other alkalies (potash or ammonia) will produce a similar reaction ; but soda is cheapest and most convenient. Ferric hydrate is an antidote to arsenic if administered directly the poison has been taken. It converts the soluble arsenic (As^Og) into insoluble ferrous arse- niate : — 2(Fe,6HO) + ASA = Fe32AsO,+ 5H,0 4- Fe2HO. Dried ferric hydrate (then become an oxyhydrate — Fe^O^IHO) [Ferri Peroxidum Hydratum, B. P.) has no action on arsenic. Even the moist recently prepared hydrate (Fe.^GHO) ceases to react with arsenic as soon as it has become converted into an oxyhydrate (Fe^OyGHO), a change which occurs though the hydrate be kept under water (W. Procter, Jr.). According to T. and H. Smith this decomposition occurs gradually, but in an increasing ratio ; so that after four months the power of the moist mass is reduced to one-half, and after five months to one-fourth. Now mere loss of water is not usually followed by any alteration of the essential chemical proper- ties of a compound. It would seem, therefore, that ferric hydrate (two molecules) (Fe4l2I10) probably suffers, on standing, actual decomposition into oxyhydrate (Fe^OgGHO) and water (3H^O), and does not merely lose water already existing in it as water. Ferric hydrate is also far more readily soluble in hydrochloric acid, tartaric acid, citric acid, and acid tartrate of potassium, than ferric oxyhy- drate. Any formula exhibiting ferric hydrate (Fe.^GHO) as a com- bination of ferric oxide and water (Fe^03,3II.^0) is, apparently, for these and other reasons, incorrect. Peroxyhydrate of Iron. Ferric Peroxyhydrate. Collect the precipitate on a filter, wash, and dry on a plate over hot water; ferric oxyh^’drate {Feri'i Peroxidum Hydratum.^ B. P.) (Fe^0^2H0 j remains. When rubbed to powder it is fit for use in medicine. Fe^GIIO == Fe,0.,2H0 + 211,0. This oxyhydrate further decomposes when heated to low redness, ferric oxide (Fe^Og) remaining. Fe., 0,21 10 = re,03 + 11,0. IRON. 129 Peroxide of Iron. Ferric oxide. The six univalent atoms of the HO, the characteristic elements of all hydrates, are thus, by two successive steps, split up into water and oxygen. But between the hydrate and oxide there obviously may be another oxyhydrate, in which only 2HO is displaced by 0", and such a compound is well known ; it is a variety of brown iron ore. The other oxyhydrate, Fe20.^2H0, is also native (needle iron ore), as well as being the Ferri Peroxidum Hydratiim^ B. P. “ Ferri Peroxidum Humidum” Fe'"^ 6H0 A variety of brown iron ore 0 ' 4H0 “ Ferri Peroxidum Hydratum” (needle ore) . Fe'"2 0"22H0 Ferric oxide The moist ferric hydrate, as already stated, when kept tor some months, even under water, loses the elements of water, and is con- verted into an oxyhydrate having the formula Fe^H^Og (limonite or brown haematite), which is either a compound of the above oxyhy- drates (Fe..04H0)+(Fe.0o2H0) , or is a definite intermediate oxy- hydrate (FeA^HO). By ebullition with water for seven or eight hours, ferric hydrate is decomposed into water and an oxyhydrate having the formula Fe^H207 (Saint-GMles), which is either a mixture of the official oxy- Fydrate (Fe2022H0) with ferric oxide (Fe203), or a definite inter- mediate body (Fe4052H0). The relation of these bodies to each other will be apparent from the following Table, in which, for con- venience, the formulae of ferric hydrate and oxide are doubled. Ferric hydrate (B. P.) (as stalactite) . . . Fe^ 12H0 Kilbride mineral (?) Fe^ OlOHO Brown iron ore (Huttenrode and Baschau) . Fe4 028H0 Old ferric hydrate (limonite) Fe^ O^fiHO Ferric oxyhydrate (B. P.) (gothite) . . . . Fe4 044H0 Boiled ferric hydrate (turgite) Fe^ 0^^2H0 Ferric oxide (red haematite) Fe^ Og The English official ferric oxyhydrate (Fe2022H0), termed in the British Pharmacopoeia Hydrated Peroxide of Iron, under the as- sumption that it is a compound of ferric oxide and water (Fe.^Og, H,0), was formerly made by mixing solutions of ferrous sulphate and carbonate of sodium and exposing the resulting ferrous carbonate to the air until it was nearly all converted into ferric oxyhydrate ; hence its old name, still sometimes seen on old bottles, of Ferri Carbonas and Ferri Subcarbonas. Ferric Oxide (another process.) Thirteenth Synthetical Reaction. — Roast a crystal or two of ferrous sulphate in a small crucible until fumes cease to be evolved ; the residue is a variety of ferric oxide (Fe.^Og) or peroxide of iron, known in trade as red oxide of iron^ colcothar^ crocus^ rouge (mineral), or Venetian red 130 THE METALLIC RADICALS. It has sometimes been used in pharmacy in mistake for the official oxyh3^drates {vide 12 th Sjmthet. Reac.), from which it differs not only in composition but in the important respect of being almost insoluble in acids. The Scale Compounds of Iron. Fourteenth Synthetical Reaction, — Repeat the twelfth re- action, introducing a little solution of citric or tartaric acid, or acid tartrate of potassium, before adding to the alkali (soda, potash, or ammonia), and notice that now no precipitation of ferric hydrate occurs. This experiment serves to illustrate, not the manufacture of a scale com- pound, but the chemistry of the manufacture. The effect is due to the formation of double compounds, ternied Am- monio-Citrate, Potassio-Citrate, Ammonio-Tartrate, Po- tassio-Tartrate, and similar Sodium compounds of Iron, which remain in solution along with the secondary pro- duct — sulphate of the alkali metal. Such ferric compounds, made with certain prescribed proportions of recentl}^ pre- jDared ferric h3"drate (from which all alkaline sulphate has been washed), and the respective acids (tartaric or citric) or acid salts (acid tartrate of posassium), etc., and the so- lutions evaporated to a syrupy consistence and spread on flat plates till diy, form the scale preparations known as Ferri et Ammonii Citras,, U. S. P., Ferri Citras^ U. S. P. (also Liquor Ferri Citratis,^ U. S. P.), Ferri et Ammonii Tartras,^ U. S. P., and Ferri Potassio-taidras,, or rather, Ferrum Tartaratum,^ B. P., Ferri et Fotassii Tartras^, U. S. P. A mixture of citrate of iron and ammonium with citrate of stiychnia yields, on evaporation, Ferri et Strychnine Gitras,^ IJ. S. P. A mixture of ferric citrate with citrate of ammonium and citrate of quinine yields, by similar treatment, the well-known scales of Ferri et Quinine Citras, B. P. and U. S. P. Specimens of these substances ma3^ be prepared b3^ at- tending to the following details. It is essential, first, that the ferric hydrate be thoroughly washed, or an insoluble ox3^sulphate will be formed; second, that the ferric hydrate be rapidly washed, or an insoluble ferric ox3diydrate will be produced; thirdly, that the whole operation be con- ducted quickly, or reduction to green ferrous salt will occur ; and, fourthl3’, that the solutions of the salts be not evaporated at a higher temperature than that stated, or decomposition will take place. IRON. 131 In the pharmacopoeial processes for the three scale compounds, the ferric hydrate is in each case freshly made from solution of ferric sulphate by precipitation with solution of ammonia : — Fe.^3S04 GAmHO == FcgGHO + 3Am2S04 Ferric Hydrate of Ferric Sulphateof sulphate. ammonium. hydrate. ammonium. the solution of ferric sulphate being made of a definite strength from a known weight of ferrous sulphate. The reason for adopting this course is that ferric hydrate is unstable and cannot be weighed, be- cause it cannot be dried without decomposing and becoming insoluble, as explained under the 12th reaction. This definite solution of ferric sulphate [Liquor Ferri Persulphatis, B. P., Liquor Ferri Tersul- phatis, U. S. P.) is made by adding six fluidrachms of sulphuric acid to half a pint of water, warming, dissolving eight ounces of crystals of sulphate of iron in the liquid, pouring in nitric acid (six fluidrachms or rather more) slightly diluted until the mixture turns from a black to a reddish color, and ruddy nitrous vapors cease to be produced ; the whole should measure eleven fluidounces, being diluted or further evaporated, as the case may be, to this bulk. GFeSO^ + 3H2SO4 -h 2HN03= 3(Fe23S04) + 2NO + 4H2O Ferri et Ammonii Gitras, U. S. P. — Ferric hydrate is dissolved in solution of citric acid, ammonia added, and the whole evaporated to dryness. To prepare the ferric hydrate, dilute eight fluidounces of the above solution of ferric sulphate with about a quart of water ; pour this into two or three pints of water containing excess of solution of am- monia — about 5 fluidounces of “ Strong Solution of Ammonia,” or 15 ounces of “Solution of Ammonia.” (If the opposite course were adopted, the alkaline liquid poured into the ferric solution, the pre- cipitate would contain ferric oxysulphate, or hydrato-sulphate, which interferes with the brilliancy of the scales.) Thoroughly stir the mixture (it will smell strongly of ammonia, if enough of the latter has been added), allow the precipitate to subside, pour away the super- natant liquid, add more water, and repeat the washing until a little of the liquid tested for by-product (sulphate of ammonium) by solution of chloride or nitrate of barium ceases to give a white precipitate (sulphate of barium). Collect the ferric hydrate on a filter, drain, and place, while still moist, in a solution of four ounces of citric acid in eight of water, placed in an evaporating basin, over a water-bath, stir frequently, until the whole, or nearly the whole, of the hydrate has dissolved. To the solution, when cold, add nearly two fluid- ounces of strongest (or five and a half of weak) solution of ammonia, filter, evaporate over a water-bath to the consistence of syrup, spread thinly on panes of glass, and dry (at a temperature not exceeding 100^ F.). The product scales off the glass in deep-red transparent laminae. Ferri et Quinioe Gitras, B. P. and U. S. P. — Ferric hydrate and pure quinia are dissolved in solution of citric acid, ammonia added, and the whole evaporated to dryness. The product contains citrate of iron, citrate of quinia, and citrate of ammonium. 132 THE METALLIC RADICALS. The ferric hydrate is obtained from four and a half fluidounces of the solution of ferric sulphate, with all the precautions described in the previous paragraph, a proportionate quantity of ammonia being employed. AVhile the ferric hydrate is being washed, prepare the quinia by dissolving one ounce of the ordinary sulphate of quinia in eight ounces of distilled water, acidified with sufficient sulphuric acid to dissolve the sulphate (about 12 fluidrachms of the official “ diluted sulphuric acid”), and to the clear liquid add solution of ammonia, well mixing the product by stirring, until the whole of the quinia is precipitated (that is, until the mixture, after thorough agitation, smells of ammonia). Collect the precipitate on a filter, let it drain, and wash away adhering solution of sulphate of ammonium by passing through it about a pint and a half of distilled water. (It will be observed that the principle involved in the preparation of quinia from its sulphate is identical with that which obtains in the precipitation of alumina, ferric hydrate, or hydrate of zinc, etc. A soluble sulphate — or, indeed, any common soluble salt — has its acidulous constituent removed by the superior affinity of the basylous radical in ammonia, or other alkali, an insoluble precipitate and a new soluble sulphate being formed. The latter is washed away, leaving the former pure. In such manipulations, when economy has to be practised, soda is the alkali generally employed. Ammonia, however, has the advantage of showing the moment when its work of removing an .acidulous radical is completed; for the salts which ammonium forms with such acidulous radicals as SO4, Cl, NO3, and C.JI^O.^ are inodorous, while it itself has a powerful odor; so long, therefore, as the salt to be decomposed is not wholly attacked, the addition of ammonia does not give an ammonia cal odor to the mix- ture, the ammonia, as such, being, in fact destroyed ; but when the work is accomplished, the quantity of ammonia last added remains as ammonia, and communicates its natural smell to the liquid.) The ferric hydrate and quinia being now washed and drained, dis- solve the former, and afterwards the latter, in a solution of three ounces of citric acid in five of distilled water, the acid liquid being warmed over a water-bath, and portions of the precipitates stirred in as fast as solution is effected. “ Let the solution cool, then add in small quantities at a time twelve fluidrachms of solution of ammonia diluted with two fluidounces of distilled water, stirring the solution briskly, and allowing the quinia which separates with each addition of ammonia to dissolve (in the acid) before the next addition is made. (Excess of ammonia must be avoided or the quinia will be precipitated.) Filter the solution, ejapbrate to the consistence of a thin syrup, and then dry in thin layers on flat porcelain or glass plates at a temperature of 100^. Remove the dry salt in flakes, and keep it in a stoppered bottle.” Long-continued exposure to sun- light causes opacity in the scales, and renders them difficultly soluble (Wood). Ferri et Strychnice Citras, U. S. P., is prepared by mixing a solution containing five grains of strychnia and five grains of citric acid with a solution containing five hundred grains of citrate of iron IRON. 133 and ammonium, evaporating the mixture at a temperature not ex- ceeding 140^ to a syrupy consistence, and scaling in the usual way by spreading it upon plates of glass. Ferrum Tartaratum, B. P. ; Ferri et Potassii Tartras, U. S. P. — Ferric hydrate is dissolved in solution of acid tartrate of potassium, and the whole evaporated to dryness. The ferric hydrate obtainable from five and a half fluidounces of the official solution of ferric sulphate by the action of ammonia, in the manner detailed in the previous paragraphs, is mixed (in a mortar), while still moist but well drained, with two ounces of acid tartrate of potassium. The whole is set aside for twenty-four hours, with occa- sionally rubbing to promote contact and reaction of the molecules (otherwise somewhat sluggish in attacking each other), and then heated in a dish over a water-bath to a temperature not exceeding 1400 F. • a pint of distilled water is then added, and the mixture kept warm until nothing more will dissolve. Filter, evaporate at a temperature not exceeding 140^ (greater heat causes decomposition), and when the mixture has the consistence of syrup, spread on panes of glass and dry (in any warm and light place shown by a thermome- ter to be not hotter than 140°). Pemoye the dry salt in flakes, and keep it in well-closed bottles. Ferri et Ammonii Tartras, U. S. P., is made by saturating solu- tion of acid tartrate of ammonium with ferric hydrate, evaporating, and scaling. The acid tartrate is prepared by exactly neutralizing half of any quantity of tartaric acid by carbonate of ammonium, and then adding the other half. The foregoing are the only official scale preparations of iron. Many others of similar character might be formed. The Citrate dissolves slowly in cold but readily in warm water. None crystallize or give other indications of definite chemical composition. Their properties are only constant so long as made with unvarying propor- tions of constituents. Their want of chemical compactness, the loose state in which the iron is combined, precludes their recognition as well-defined chemical compounds, yet possibly enables them to be more readily assimilated as medicines than some of the more definite ferrous and ferric salts. Wine of Iron, or “Steel” wine [Vinum Ferri, B. P.), made by digesting iron wire in sherry wine, probably contains tartrate of po- tassium and iron and other iron salts, formed by action of the metal on the acid tartrate of potassium and tartaric, citric, malic, and acetic acids present in the wine. Vinum Ferri Gitratis, B. P., is a solution of ammonio-citrate of iron in orange wine. Black Hydrate of Iron. Ferro-ferric Hydrate. Ferri Oxidum Magneticum^ B. P. Fifteenth Synthetical Reaction . — To tivo-thirds of a small quantity of a solution of ferrous sulphate add a little sul- phuric acid ; warm, and gradually add nitric acid, as de- scribed in the tenth reaction, care being taken not to allow 12 134 THE METALLIC RADICALS. one drop more nitric acid than necessary to fall into the test-tube. Add the other third of ferrous sulphate, shake, and pour the liquid into excess of an alkali ; black (at first brown) hydrate of iron, or ferroso-ferric hydrate (Fe 38 HO = re 2 HO, Fe^GHO), is produced. Fe.,3SO, + FeSO, + 8 NaHO = Fe 38 HO + 4Na^SO, Ferric Ferrous Soda. Blk. hydrate Sulphate sulphate. sulphate. of iron. of sodium. It is so readily attracted by a magnet, even when moist, as to collect round the latter when immersed in the super- natant liquid. Hence the B. P. name, Ferri Oxidum Mag- neticum. In this process the nitric acid oxidizes the hydrogen of the sul- phuric acid, the sulphuric radical uniting with the ferrous sulphate, whose iron is at the same time altered from the ferrous to the ferric condition, ferric sulphate being formed. If too much nitric acid be employed, the second portion of ferrous sulphate will also be converted into ferric salt, and the solution, on the addition of alkali, yield only red ferric hydrate. This result may be avoided by evaporating the solution of ferric sulphate nearly to dryness, thus boiling off excess of nitric acid, or by pouring first the ferric and then the ferrous liquid into the alkali and thoroughly stirring the mixture ; any nitric, acid is then neutralized and rendered incapable of oxidizing the ferrous sulphate subsequently added. Black hydrate of iron is decomposed by heat, yielding, in a closed vessel, oxyhydrates, and, finally, black oxide of iron or ferroso-ferric oxide. Heated in the air it absorbs oxygen and gives ferric oxide. The black forge-scales, which collect near the blacksmith’s anvil, have the composition of ferroso-ferric oxide ; the black magma formed on exposing a mixture of iron and water to the air is ferroso-ferric hydrate ; but these varieties are apt to contain particles of metal, and, hence, give hydrogen gas when dissolved in acids — a character which distinguishes them from the official preparation. If a dried specimen of the black hydrate of iron be required, the mixture should be well boiled and then set aside for an hour or two to favor aggregation of the particles, the mixture filtered, and the precipitate washed until the washings contain no trace of sulphate (indicated by a white precipitate with chloride of barium). Black hydrate of iron absorbs oxygen even at the temperature of the water- bath; it should consequently be dried at 120^, a temperature at which only slight oxidation occurs. Pernitrate of Iron. Ferric Nitrate. Sixteenth Synthetical Reaction , — Place a few iron tacks in dilute nitric acid and set aside ; solution of ferric nitrate, or pernitrate of iron, is formed (FeyGNOg). Fe., + SIINOg = Fe.GNOg + 411,0 + 2NO Iron. Xitric Ferric Water. Nitric acid. nitrate. oxide. IRON. 135 This solution, made with care, and of a prescribed strength, forms the Liquor Ferri Pernitratis, B. P. (sp. gr. 1.107) and U. S. P. (sp. gr. 1.065). The process is as follows : Four and a half fluidounces of nitric acid are diluted with sixteen ounces of distilled water, and one ounce of iron wire, free from rust, dissolved in the mixture, the latter being kept cool to avoid violence of action. The liquid is finally filtered and diluted to thirty fluidounces. Reduced Iron. Seventeenth Synthetical Reaction . — Pass hydrogen gas (dried by passing over pieces of chloride of calcium con- tained in a tube, or through sulphuric acid in a wash bottle) into a small quantity of ferric oxyhydrate or oxide (“ subcarbonate,’’ U. S. P.) contained in a tube arranged horizontally (a test-tube, the bottom of which has been accidentally broken, answers very well), the oxide being- kept hot by a gas-flame ; oxygen is removed from the oxide by the hydrogen, steam escapes at the open end of the tube, and after a short time, when moisture ceases to be evolved, metallic iron, in a minute state of division, remains. Fe.Og + 3H, = Fe^ + 3H,0 Ferric Hydrogen. Iron. Water, oxide. Wliile still hot throw the iron out into the air ; it takes Are and falls to the ground as oxide. If the ferric oxide is reduced in a gun-barrel heated by a strong furnace, the particles of iron aggregate to some extent, and, when cold, are only slowly oxidized in dry air. This latter form of re- duced iron is Fer r4duit, or Quevennd s Iron, the Ferri pulvis, or Ferrum Redactum, B. P. and U. S. P. — “ a fine grayish-black pow- der, strongly attracted by the magnet, and exhibiting metallic streaks when rubbed with firm pressure in a mortar.” It is often admin- istered in the form of lozenges [Trochisci Ferri Redacti, B.P.) gum and sugar protecting the iron from oxidation as well as forming a vehicle for its administration. Note. — The spontaneous ignition of the iron in the above experi- ment is an illustration of the influence of minute division on chemi- cal affinity. The action Js the same as occurs whenever iron rusts, and the heat evolved and amount of oxide formed is not greater from a given quantity of iron ; but the surface exposed to the action of the oxygen of the air is, in the case of this variety of reduced iron, so enormous compared with the weight of the iron, that heat cannot be conducted away sufficiently fast to prevent elevation of temperature to a point at which the whole becomes incandescent. In the slow rusting of iron, escape of heat occurs, but is not ob- 13G THE METALLIC RADICALS. served, because spread over a length of time ; in the spontaneous ignition of reduced iron the whole is evolved at one moment. Ferric Pyrophosphate. Eighteenth Synthetical Reaction, — To solution of pjH’o- phosphate of sodium add solution of persulphate of iron ; a 3"ellowisli-wliite precipitate of ferric p^H’ophospliate (Fe^ 3P2O-, 9H2O) separates. This precipitate, dissolved in solution of citrate of ammonium, and evaporated, 3delds apple-green scales (Fer 7 'i pyrophosphas^ U. S. P., contain- ing fort3-eight per cent, of anhydrous p3n'ophosphate). (b) Reactions Imping Analytical Interest {Tests). (The ironfcccurring as a ferrous salt.) First Analytical faction, — Pass sulphuretted hydrogen (H2S) through a ^Piition of a ferrous salt (^.g., ferrous sulphate) slightl3^^ftlulated hy hydrochloric acid; no pre- cipitate occurs. This is a valuable negative fact, as will be evident pre- sentl3^ Second Analytical Reaction. — Add sulph3^drate of am- monium (NH^HS) to solution of a ferrous salt ; a black pre- cipitate of ferrous sulphide (FeS) falls. FeSO, + 2AmHS = FeS -f Am2SO, -f H^S. Third Analytical Reaction. — Add solution of ferrocwa- nide of potassium (yellow prussiate of potash), K^Fe"C3"j;, or K^Fcy"", to solution of a ferrous salt; a precipitate (K^^Ye^^Fcy) falls, at first white, but rapidl3^ becoming blue, owing to absorption of ox3’gen. Fourth Analytical Reaction. — To solution of a ferrous salt add ferridc3^anide of potassium (red prussiate of pot- ash), K^Fe'"2C3Y,, or K^Fdcy ; a precipitate (Fe"j.Fdcy) resembling Prussian blue (Turnbull’s blue) is thrown down. Other Analytical Reactions. — The precipitates produced from ferrous solutions on the addition of alkaline carbo- nates, phosphates, and arseniates, as already described in the synthetical reactions of ferrous salts, are characteristic, and hence have a certain amount of anal3Tical interest, but are inferior in this respect to the four reactions above men- tioned. Note. — Tlie alkalies (solution of potash, soda, or ammo- nia) are incomplete precipitants of ferrous salts, and are IRON. 13t therefore almost useless as tests. To solution of a ferrous salt acid ammonia (NH^HO); on filtering and testing with sulphydrate of ammonium, iron will still be found in the solution. To another portion of the ferrous solution add a few drops of nitric acid and boil ; this converts the fer- rous into ferric salt, and now alkalies will wholly remove the iron, as already twice seen during the performance of the synthetical experiments. In actual analysis, the separation of iron as ferric hydrate is an operation of frequent performance. This is always accomplished by the addition of alkali, and, if the iron occurs as a ferrous salt, by previous ebullition with a little nitric acid. Ferrocyanide and ferrid- cyanide of potassium are the tests used in distinguishing ferrous from ferric salts. (The iron occurring as a ferric salt.) Sixth Analytical Reaction, — Through a ferric solution (ferric chloride, e, g,) pass sulphuretted hydrogen ; a white precipitate of the sulphur of the sulphuretted hydrogen falls, and the ferric is reduced to a ferrous salt, the latter remaining in solution. This reaction is of frequent occur- rence in practical analj^sis. + 2H,S = 4FeCl, + 4HC1 + S,. Seventh Analytical Reaction, — Add sulphydrate of am- monium to a ferric solution ; the latter is reduced to the ferrous state, and black ferrous sulphide (FeS) is precipi- tated as in the second analytical reaction, sulphur being set free. Eighth Analytical Reaction, — To a ferric solution add ferrocyanide of potassium (K^FeCyg, or K^Fcy"") ; a pre- cipitate of Prussian blue, the common pigment, occurs (Fe"'43Fe"Cyg, or Fe'^'^Fcy^^g). {Ferri Ferrocyanidum,^ U. S. P.) Ninth Analytical Reaction, — To a ferric solution add solution of ferridcyanide of potassium ; no precipitate occurs, but the liquid is darkened to a greenish or olive hue, according to the strength. Tenth Analytical Reaction. — This is the production of a red precipitate of ferric hydrate, on the addition of alkalies to ferric salts, and is identical with the twelfth synthetical reaction. Note . — This reaction illustrates the conventional character of the terms synthesis and analysis. It is of equal importance to the manu- 12 * 138 THE METALLIC RADICALS. facturer and the analyst, and is synthetical or analytical according to the intention with which it is performed. Other ferric reactions have occasional analytical inter- est. In neutral ferric solutions the tannic acid in aqueous infusion of galls occasions a bluish-black inky precipitate, the basis of ordinary writing ink. (The Mistura Ferri Aromatica of the British Pharmacopoeia, made by digesting metallic iron in an infusion of various vegetable substances, contains tannate, or rather tannates of iron : it is commonly known in Ireland by the name of Heberden’s Ink, after the physician by whom it was first used. It contains about 1 grain of iron in 1 pint.)- Sulphocyanide of Potassium (KCyS) causes the formation of ferric sulphocy^anate, which is of deep blood-red color.- There is no ferric car- bonate ; alkaline carbonates cause the precipitation of ferric hydrate, while carbonic acid gas escapes. Note . — Cyanogen (NC, or Cy'), ferrocyanogen (FeCgNg, or FeCy^, or simply Fey""), and ferrideyanogen (Fe.^Cyi 2 , Pdey^^), are radicals which play the part of non-metallic elements, just as am- monium in its chemical relations resembles the metallic elements. They will be again referred to. Memorandum.— reader must on no account omit to write out equations or diagrams expressive of each of the reactions of iron, analytical as well synthetical. It is pre- sumed that this has already been done immediately after each reaction has been performed. DIRECTIONS FOR APPLYING THE FOREGOING ANALYTICAL REAC- TIONS TO THE ANALYSIS OF AN AQUEOUS SOLUTION OF SALTS CONTAINING ONE OF THE METALS, ZiNC, ALUMI- NIUM, Iron. Add solution of ammonia gradually : — A dirty^-green precipitate indicates iron in the state of a ferrous salt. A red precipitate indicates iron in the state of a ferric salt. A white precipitate, insoluble in excess, indicates the presence of an aluminium salt. A white precipitate, soluble in excess, shows zinc. These results may be confirmed by the application of some of the otlier tests to fresh portions of the solutiop. ZINC, ALUMINIUM, IRON. 139 TABLE OF SHORT DIRECTIONS FOR APPLYING THE FOREGOING ANA.LYT1CAL REACTIONS TO THE ANALYSIS OF AN AQUEOUS SOLUTION OF SALTS OF OISTE, TWO, Oil ALL THREE OP THE METALS, Zinc, Aluminium, Iron. Boil about half a test-tubeful of the solution with a few drops of nitric acid. This insures the conversion of ferrous into ferric salts, and enables the next reagent (ammonia) completely to precipitate the iron. Add excess of ammonia, and shake the mixture. Filter. Precipitate Filtrate A1 Fe.* Zn. Dissolve in HCl, add excess of KHO, Test by AmHS. stir, filter. (white ppt.). Ppt. Filtrate Fe Al. (red ppt.). Neutralize by HCl, and add excess of AmHOf (white ppt.). Note I. — If iron is present, portions of the original solu- tion must be tested by ferridcyanide of potassium for ferrous, and by ferrocyanide for ferric salts ; dark-blue precipitates with both indicate both salts. Note II. — If no ferrous salt is present, ebullition with nitric acid is unnecessary. It is, perhaps, therefore advi- sable always to determine this point by previously testing a little of the original solution with ferridcyanide ; if no blue precipitate occurs, the nitric acid treatment may be omitted. Chart for all Metals hitherto considered. The following Table {vide p. 141) is perhaps the best, but not the only adaptation of the ordinary reactions to systematic analysis. It is little else than the addition of the analytical scheme for the * The aluminium precipitate (AlgCHO) is white, the iron (Fe^BHO) red. If the precipitate is red, iron must be and aluminium may be present ; if white, iron is absent, and further operation on the preci- pitate unnecessary. t Alumina, when in small quantity, is sometimes prevented from being precipitated by ammonia through the presence of organic mat- ter derived from the. filter paper by action of the potash. In cases of doubt, therefore, before adding ammonia boil the liquid with a little nitric acid, which destroys any organic matter. 140 THE METALLIC RADICALS. third group to that of the first two groups. As before, analysis is commenced by the addition of chloride of ammonium (NH^Cl) to prevent partial precipitation of magnesium, and ammonia (NH^HO) to neutralize any acid. The latter would attack the chief group- precipitant, sulphydrate of ammonium (NH^HS), preventing its useful action, and causing a precipitation of the sulphur it commonly contains. Note . — When a test gives no reaction, absence of the body sought for may be fairly inferred. If group-tests (that is, tests which pre- cipitate a group of substances) give no reaction, the analyst is saved the trouble of looking for either member of the respective groups. ZINC, ALUMINIUM, IRON. Hi hi ^ O h S ’-^ o h ^ o O .^W O C ^ ky( 't-5 NJ -r-l .-p ^ s .£^3 * ^ n- Sta s S o = scu . s' <1 pH Ph c3 O g: '■’Cp offio H (-1 _h 'O TJ CO Prt . 2 S p -1 p C tif *-P pN ^ ^ ^ oO o3 a -M P ^ O >73 <1 . "o fM a M.s "a ^ Gi W sS ... rp <1^ P a-SPS I ^cg.SP K d -h br^ as I ^ cTu ! s ^ ^ n3 P- rP m ^ S ® p^ ^ a S ^ P^ ° £*a gWy“ >% 141 Add, also, a few drops of HNO 3 if Fe be present — i. e., if the ppt. be black. {Vide notes on pp. 136 and 139.) 142 THE METALLIC RADICALS. QUESTIONS AND EXEECISES. 207. Name the chief ores of iron. 208. How is the metal obtained from the ores ? 209. What is the chemical difference between cast iron, wrought iron, and steel ? 210. Explain the process of welding. 211. What is the nature of chalybeate waters ? 212. Illustrate by formulae the difference between ferrous and fer- ric salts. 213. Under what different circumstances may the atom of iron be considered to exert bivalent, trivalent, and sexivalent activity ? 214. Write a paragraph on the nomenclature of iron salts. 215. Give a diagram of the official process for the preparation of ferrous sulphate. 216. In what respects do Sulphate of Iron, Granulated Sulphate of Iron, and dried Sulphate of Iron differ V 217. How is ferrous sulphate obtained on the large scale ? 218. Mention the chemical names of wffiite, green, and blue vitriol. 219. Why does ferrous sulphate become browm by prolonged ex- posure to air ? 220. Give a diagram showing the formation of Ferrous Carbonate 221. Describe the action of atmospheric oxygen on ferrous carbon- ate : can the effect be prevented ? 222. In what order would you mix the ingredients of Mistura \ Ferri Composita, and why ? 223. Write out an equation illustrative of the formation of the ' Phosphate of Iron. 224. Why is acetate of sodium used in the preparation of ferrous i phosphate ? I 225. Which four compounds of iron may be formed by the direct union of their elements ? • 226. Give the official .method for the preparation of Solution of j Ferric Chloride. 227. Of what use is the spirit in Tincture of Perchloride of Iron ? ! 228. How may Ferrous be converted into Ferric Sulphate ? j 229. What is the formula of Ferric Acetate? and how is it pre- pared for use in pharmacy ? j 230. Express, by formulae, the difference betw^een Ferri Peroxidum | Humidum, B. P., and Ferri Peroxidum Hydratum, B. P. I 231. How does Ferric Hydrate act as an antidote to arsenic ? | 232. What are the properties of anhydrous ferric oxide? 233. What are the general characters and mode of production of ! the medicinal scale preparations of iron? 234. In wdiat state is the iron in Vinum Ferri, B. P. ? | 235. What other form of AVine of Iron is official in Great Britain ? ; 236. Give equations illustrating the chief steps in the artificial ( production of the so-called Magnetic Oxide of Iron. 237. How is precipitated magnetic oxide of iron distinguished from the varieties made directly from the metal ? ARSENICUM, ANTIMONY. 143 238. Why is magnetic oxide of iron officially directed to be dried at a temperature not exceeding 120® Fahr. ? 239. Give a diagram showing the formation of Ferric Nitrate. 240. Work out a sum showing how much anhydrous ferric oxide will yield, theoretically, one hundred-weight of iron. Ans. 160 lbs. 241. What are the properties of anhydrous ferric oxide ? 242. Give the characteristic tests for iron, distinguishing between ferrous and ferric reactions, and illustrating each by an equation or a diagram : — a. Sulphydrate of ammonium. h. Ferrocyanide of potassium. c. Ferridcyanide of potassium, d. Caustic alkalies. e. Sulphocyanate of potassium. 243. Describe the action of ammonia on salts of iron, aluminium, and zinc respectively. 244. What precautions must be used in testing for calcium in the presence of iron ? 245. How is magnesium detected in the presence of zinc ? 246. How is aluminium detected in the presence of magnesium ? 247. Draw up a scheme for the analysis of an aqueous liquid con- taining salts of iron, barium, and potassium. 248. How may zinc, magnesium, and ammonium be consecutively removed from aqueous solution ? ARSENICUM, ANTIMONY. These two elements resemble metals in appearance and in the character of some of their compounds ; but they are still more closely allied to the non-metals, especially to phosphorus and nitrogen They are quinquivalent (As^ Sb^), as seen in arsenic anhydride (AS 2 O 5 ) and pentachloride of antimony (SbCl 5 ), but usually exert trivalent activity only ( As^'S Sb'"^), as seen in the hydrogen and other compounds (ASH 3 , ASCI 3 , AsBr 3 , Asig). A few preparations of these elements are used in medicine ; but all are more or less power- ful poisons, and hence have considerable toxicological interestf The iodide {Arsenici lodidum, U. S. P.) is made by cautiously fusing together atomic proportions of arsenicum and iodine. It is an orange- red crystalline solid soluble in water. The Ijk^uot ATscudci 6t Hydrargyri lodidi, U. S. P., is made by dissolving iodide of arseni- cum and red iodide of mercury in water, in the proportion of 1 grain of each of the solids to 104 grains of water. Arsenicum is an exception to the rule that the atomic weights (taken in grains, grammes, or other weight) of elements, under similar circumstances of temperature and pressure, give equal volumes of vapor, the equivalent weight (75) of arsenicum only occupying halt such a volume. Hence, while the molecular weights (that is, double the atomic weights) of oxygen (0^ = 32), hydrogen (H, = 2), nitrogen (N 2 28), etc., give a similar bulk of vapor at any given 144 THE METALLIC RADICALS. temperature and pressure, the double atomic weight of arsenicum, (As2 = 150), at the same temperature and pressure, only affords half this bulk. It would appear, therefore, that the molecule of arsenicum contains four atoms, and that its formula is As^. As with sulphur, however, arsenicum, in the state ordinarily known to us, may be ab- normal, and a variety yet be found in which the molecular weight is double (instead of quadruple) the atomic weight. From observed analogy between the two metals, the molecular constitution of antimony is probably similar to that of arsenicum. ARSENICUM. Symbol As. Atomic weight 75. Sources . — Arsenical ores are frequently met with in nature, the commonest being the arsenio-sulphide of iron (FeSAs). This mineral is roasted in a current of air, the oxygen of which, combining with the arsenicum, forms common white arsenic (As.^Og) {Acidum Arseni- osum, B. P. and U. S. P.) which is condensed in chambers or long flues. It commonly “ occurs as a heavy white powder, or in sublimed masses, which usually present a stratified appearance, caused by the existence of separate layers, differing from each other in degrees of opacity.” Realgar (red algar) is the red native sulphide (As.^S2), and orpiment [auripigmentum, the golden pigment) the yellow native sulphide (As^Sg) of arsenicum. Reactions having (a) Synthetical and (6) Analytical Interest. (a) Reactions having Synthetical Interest. Alkaline Solution of Arsenic. First Synthetical Reaction. — Boil a grain or two of pow- dered arsenic (AS 2 O 3 ) in water containing an equal weight of carbonate of potassium, and, if necessary, filter. The solution, colored with compound tincture of lavender, and containing 4 grains of arsenic per ounce, forms the Liquor Arsenicalis.^ B. P., or Liquor Potassii Arsenitis.^ U. S. P. (FowleFs Solution.) Note . — This official solution does not generally contain arsenite of potassium ; for the arsenic does not decompose the carbonate of potassium, or only after long boiling. From concentrated solutions carbonic acid gas is more quickly eliminated. Arsenious Acids and other Arsenites. When arsenic (AS2O3) is dissolved in excess of solutions of potash or soda, arsenides are formed having the formulae Kn2As03 and ARSENICUM. 145 NaH^AsOg. Boiled with excess of arsenic, one molecule of these salts combines with one of arsenic. The usual character of such compounds is that of oily alkaline liquids. Arsenic or arsenious anhydride (the so-called arsenious acid), when dissolved in water, yields true arsenious acid (HgAsOg), the arsenite of hydrogen. -^^2^3 + 3H2O = 2H3ASO3 Arsenious Water. Arsenious anhydride. acid. Acid Solution of Arsenic. Second Synthetical Reaction, — Boil arsenic with dilute hydrochloric acid. Such a solution made with prescribed proportions of acid and water, and containing 4 grains of arsenic (As^Og) per ounce, forms Liquor Arsenici Hydro- chlo7'icus, B. P. {Liquor Arsenici Ghloridi^ U. S. P.) (De Valangin^s Solution contained a grain and a half per ounce.) Note . — No decomposition occurs in this experiment. The liquid is simply a solution of arseftic in dilute hydrochloric acid. These two solutions may be preserved for analytical operations. Mem . — The practical student should boil arsenic in water also, and thus have an acid, alkaline, and aqueous solution for analytical comparison. Arsenicum. Third Synthetical Reaction. — Place a grain or less of arsenic at the bottom of a narrow test-tube, cover it with about half an inch or an inch of small fragments of dry charcoal, and hold the tube, nearly horizontally, in aflame, the mouth being loosely covered by the thumb. At first let the bottom of the tube project slightly beyond the flame, so that the charcoal may become nearly red-hot ; then heat the bottom of the tube. The arsenic will sublime, become deoxidized by the charcoal, carbonic oxide being formed, and arsenicum deposited in the cool part of the tube as a dark mirror-like metallic incrustation. There is a characteristic odor, resembling garlic, emitted during this operation, probably due to a partially oxidized trace of arseni- cum which escapes from the tube ; for arsenic alone does not give this odor ; moreover, arsenicum being a freely oxidizable element, its vaporous particles could scarcely exist in the air in an entirely unoxidized state. Metallic arsenicum [Arsenicum, U. S. P.) may be obtained in large quantities by the above process if the operation be conducted in vessels of commensurate size. But performed with great care, in narrow tubes, using not charcoal alone, but hlackflux (a mixture of charcoal and carbonate of potassium obtained by heating acid tar- 146 THE METALLIC RADICALS. trate of potassium in a test-tube or other closed vessel till no more fumes are evolved), the reaction has considerable analytical interest, the garlic odor and the formation of the mirror-like ring being highly characteristic of arsenicum. Compounds of mercury and antimony, however, give sublimates which may be mistaken for arsenicum. Arsenic Acid and other Arseniates. Fourth Synthetical Reaction , — Boil a grain or two of arsenic with a few drops of nitric acid until red fumes cease to be evolved ; evaporate the solution in a small dish to dryness, to remove excess of nitric acid ; dissolve the residue in water; the product is Arsen'ic acid (HgAsO^). Arsenic acid, when strongly heated, loses the elements of water, and arsenic anhydride remains (As.^05). Arsenic anhydride readily absorbs water and becomes arsenic acid (H3ASO4). Arsenic acid is readily reduced to arsenious by the action of reducing agents such as sulphurous acid, H3ASO4-I-H2SO3 =H3As03+H2S0,. Salts analogous to arsenic acid, the arseniate of hydrogen, are termed arseniates, and have the general formula R'3 AsO^. The am- monium arseniate (Am.^HAsO^) may be made by neutralizing arsenic acid with ammonia. Its solution in water forms a useful reagent. Arsenic acid is used as an oxidizing agent in the manufacture of the well-known dye, magenta. Arsenite and arseniate of sodium are used in the cleansing opera- tions of the calico-printer. Pyroarseniate and Arseniate of Sodium. Fifth Synthetical Reaction , — Fuse a minute fragment of common white arsenic (As^^Og) with nitrate of sodium (NaNOg) and dried carbonate of sodium (Na.^C 03 ) in a porcelain crucible, and dissolve the mass in water; solution of arseniate of sodium (Na^HAsOJ results. As.Og + 2NaN03 + Na.^COg = Ka^As.O^ + N^Og + CO, Arsenic. Nitrate of Carbonate Pyroarseniate Nitrous Carbonic. sodium. of sodium. of sodium. anhydride, acid gas. The official proportions (B. P) are 10 of arsenic to 8| of nitrate of sodium and 5 | of dried carbonate, each powdered, the whole well mixed, fused in a crucible at a red heat till effervescence ceases, and the liquid poured out on a slab. The product is pyroarseniate of sodium (NagAs., 0 .). Dissolved in water, crystallized, and dried, the salt has the formula Na.2HAs04, 7H2O {Sodii Arse 7 iias, U. S. P.). Na^As^O, + ISH^O = 2 (Na 2 lIAs 04 , 111 , 0 ). Heated to 300 ^ F. the crystals lose all water. A solution of 4 grains of the anhydrous salt (Na.^lIAsO^) in 1 ounce of water forms the Liquor Sodii Arseniatis, U. S. P. The anhydrous salt is used ARSENICUM. 14T in this preparation because the crystallized is of somewhat uncertain composition. The fresh crystals are represented by the formula Na.TIAsO^, I2H2O (= 53.7 per cent of water) ; these soon effloresce and yield a stable salt having the formula Na^^HAsO^, 7H2O (= 40.4 per cent, of water). To avoid the possible employment of a mixture of these bodies, the invariable anhydrous salt is officially used, constancy in the strength of a powerful preparation being thereby secured. The student will find useful practice in verifying the above numbers representing the centesimal proportion of water in the two arseniates of sodium. This will readily be accomplished if what has already been stated respecting a symbol representing a number as well as a name, and the remarks concerning molecular weight, be remembered. The shape of each of the two varieties of ars'eniate of sodium (Na2HAs04, I2H2O, and Na2HAs04, 7H2O) is identical with that of the corresponding phosphate of sodium (Na2HP04, I2H2O, and Na2HP04, 7H2O) ; the structure of the molecule of the 12-arseniate is the same as that of 12-phosphate, and the 7-arseniate as that of the 7-phosphate ; the two former are isomorphous, the two latter are isomorphous. This is only one instance of the strong analogy of arsenicum and its compounds with phosphorus and its corresponding compounds. The preparation and characters of the next substance, arseniate of iron, will remind the learner of phosphate of iron. Arseniate of Iron. Ferrous Arseniate. Sixth Synthetical Reaction . — To solution of arseniate of sodium add a little acetate of sodium and then solution of ferrous sulphate, a precipitate of ferrous arseniate occurs (Fe 32 As 04 ) {Ferri Arsenias.^ B. P.). On the large scale 4 parts of dried arseniate and 3 of acetate dissolved in 40 of water, mixed with 9 of sulphate in 60 of water, may be employ^ed. The precipitate should be collected on .a calico filter, washed, squeezed, and dried at a low tem- perature (100° F.) over a wash-bath to avoid excessive oxidation. 2Na,HAsO, + 2 NaC 2 [l 302 + 3FeSO, Arseniate of Acetate of Ferrous sodium. sodium. sulphate. 3Na,SO, + 2HC,H,0,. Sulphate of Acetic acid, sodium. The use of the acetate of sodium is to insure the occurrence of acetic acid in solution, where otherwise would be free sulphuric acid. Sulphuric acid is a solvent of ferrous arseniate ; acetic acid is not. It is impossible to prevent the separation of sulphuric acid, if only ferrous sulphate and arseniate of sodium be employed. At the instant of precipitation ferrous arseniate is white, but rapidly becomes of a green or greenish-blue color, owing to absorption of oxygen and formation of a ferroso-ferric arseniate. It is a tasteless amorphous powder, soluble in acids. = Fe 32 AsO^ + Ferrous arseniate. 148 THE METALLIC RADICALS. The Hydride and SuliMdes of Arsenicum^ and the Arsenites and Arseniates of Copper and of Silver are men- tioned in the following analytical paragraphs : — (b) Reactions having Analytical Interest ( Tests). First Analytical Reaction. — Cut or break off portions of the tube containing the sublimate of arsenicum obtained in the third synthetical reaction, put them into a test-tube and heat the bottom of the latter, holding it nearly hori- zontally, and partially covering the mouth with the finger or thumb; the arsenicum (AsJ will absorb oxygen from the air in the tube, and the resulting arsenious anhydride (AS2O3) be deposited on the cool part of the tube in char- acteristic octahedral (oxt'w, okto^ eight ; iSpa, hedra.^ side) crystals, more or less perfect. Microscopic Test. — Prove that the crystals are identical in form with those of common white arsenic, by heating a grain or less of the latter in another test-tube, examining the two sublimates by a good lens or compound microscope. Notes . — The production of arsenicum and its subsequent oxidation are test-reactions perhaps not quite so delicate as some that follow, requiring more material for their satisfactory performance ; yet the form of the crystals is charateristic, no other volatile body being likely to be mistaken for them ; and in toxicological cases it is desirable to obtain the arsenicum in a similar state to that in which probably it originally exerted its effects ; the processes alluded to are therefore of considerable importance. Moreover, arsenicum, ready for sublimation to crystalline arsenic, is easily obtained from solution by the following reaction : — Second Analytical Reaction.— Vlace a thin piece of cop- per, about a quarter inch wide and half inch long, in a solution of arsenic, acidified by hydrochloric acid, and boil (nitric acid must not be present, or the copper itself will be dissolved) ; arsenicum is deposited on the plate in a metallic condition, an equivalent portion of copper going into solution. Pour off the supernatant liquid from the copper, wash the latter once or twice with water, dry the piece of metal by holding in the fingers and passing through a flame, and finally place it at the bottom of a clean dry narrow test-tube ; sublime as described in the last reaction, again noticing the form of the resulting crystals. This is commonly known as Reinsclfs test for arsenicum. The tube may be reserved for subsequent comparison with an antimonial sublimate (p. 100). ARSENICUM. 149 Note . — Copper itself frequently contains arsenicum, a fact that may not, perhaps, much trouble an operator so long as he is perform- ing experiments in practical chemistry merely for educational pur- poses ; but when he engages in the analysis of bodies of unknown composition, he must assure himself that neither his apparatus nor materials already contain the element of which he is in search. The detection of arsenicum^ in metallic copper is best accom- plished by distilling a mixture of a few grains of the sample with five or six times its weight of ferric hydrate or chloride (free from arsenicum) and excess of hydrochloric acid. The arsenicum is thus volatilized in the form of chloride of arsenicum, and may be condensed in water and detected by sulphuretted hydrogen (5th Analytical Keaction) or Reinsch’s test. The ferric chloride solution is, if neces- sary, freed from any trace of arsenicum by evaporating once or twice to dryness with excess of hydrochloric acid (Odling). Third Analytical Reaction — MarsNs test. — Generate hydrogen in the usual way from water by zinc and sul- phuric acid, a bottle of about four or six ounces capacity being used, and a funnel-tube and short delivery-tube passing through the cork in the usual manner (described on page 81). Diy the escaping hydrogen (except in rough experiments, when it is unnecessary) by adapting to the delivery-tube, by a pierced cork, a short piece of wider tubing containing fragments of chloride of calcium. To the opposite end of the drying-tube fit a piece of narrow tubing ten or twelve inches long, made of hard German glass, and having its aperture narrowed by drawing out in the flame of the blowpipe. When the hydrogen has been escaping at such a rate and for a sufficient number of minutes as to warrant the operator in concluding that all the air originally existing in the bottle has been ex- pelled, set light to the jet, and then pour eight or ten drops of the aqueous solution of arsenic, or three or four drops of the acid or alkaline solution of arsenic, previously pre- pared, into the funnel-tube, washing the liquid into the generating-bottle with a little water. The arsenic is at once reduced to the state of arsenicum, and the latter combines wdth some of the hydrogen to form hydride of arsenicum or arseniuretted ly^drogen gas (AsHg). Imme- diately hold a piece of earthenware or porcelain (the lid of a porcelain crucible, if at hand) in the hydrogen jet at the extremity of the delivery-tube ; a brown spot of con- densed arsenicum is deposited. Collect several of these spots, and retain them for future comparison with antimo- nial spots (p. 160). 13 * 150 THE METALLIC RADICALS. The separation of arsenicum in the flame is due to the decomposi- tion of the arseniuretted hydrogen by the heat of combustion. The cool porcelain at once condenses the arsenicum, and thus prevents its oxidation to white arsenic, which would otherwise take place at the outer edge of the flame. Hold a small beaker or wide test-tube over the flame for a few minutes ; a white film of arsenic (As.^Og) will be slowly deposited, and may be further examined in contrast with a similar antimonial film (p. 160). During these experiments the effect produced by the arsenical vapors on the color of the hydrogen-flame will have been noticed ; they give it a dull livid bluish tint. This is characteristic. Apply the flame of a gas-lamp to the middle of the hard delivery-tube ; the arseniuretted hydrogen, as before, is decomposed by the heat, but the liberated arsenicum (As^) immediately condenses in the cool part of the tube beyond the flame, forming a dark metallic mirror. The tube may be removed and kept for comparison with an antimonial deposit. Note I. — Zinc, like copper, frequently itself contains arsenicum. When a specimen free from arsenicum is met with, it should be re- served for analytical experiments, or a quantity of guaranteed purity should be purchased of the chemical-apparatus maker. Sulphuric acid is more easily obtained free from arsenic. Note II. — In delicate and important applications of Marsh’s test, magnesium may be substituted for zinc with safety, as arsenicum has not yet been, nor is it likely to be, found in magnesium. Mag- nesium in rods is convenient for this purpose, and may be obtained from most dealers in chemicals. Note III. — Arseniuretted hydrogen is decomposed by strong sul- phuric acid ; hence chloride of calcium is used in drying the gas. Fou7ih Analytical Reaction — Fleitniann'^ s test. — Gene- rate hj^drogen by heating to near the boiliag-point a strong solution of caustic soda or potash and some pieces of zinc. Drop into the test-tube a little arsenical solution, and spread over the mouth of the tube a cap of filter-paper moistened with one drop of solution of nitrate of silver. Again heat the tube, taking care that the liquid itself shall not spirt up on to the cap ; the arsenic is reduced to ar- senicum, the latter uniting with the hydrogen as in Marsh’s test ; and the arseniuretted hydrogen passing up through the cap reacts on the nitrate of silver, causing the produc- tion of a purplish-black spot. AsIIg -f 311,0 -f GAgNOg = IlgAsOg + GIINOg -f 3Ag,. ARSENICUM. 151 Note . — This reaction is particularly valuable, enabling' the ana- lyst to quickly distinguish arsenicum in the presence of its sister element antimony, which, although it combines with the hydrogen evolved from dilute acid and zinc, does not combine with the hydro- gen evolved from solution of alkali and zinc, and therefore does not give the effect just described. Fifth Analytical Reaction . — To a solution of chloride of tin in strong hydrochloric acid add a very small quantity^ of any arsenical solution. Arsenicum then separates, espe- cially on the application of heat, giving the mixture a yel- lowish and then brownish hue or grayish-brown turbidity^, or even a sediment of gray-brown flocks, according to the amount present. Much water prevents the reaction ; its presence, therefore, must be avoided as much as possible ; indeed a liquid saturated by hydrochloric acid gas gives best results. Arsenic in sulphuric or hydrochloric acids or in tartar emetic, etc., may^ be detected by this method. Ni- trates, such as subnitrate of bismuth, must first be heated with sulphuric acid to remove the nitric radical before ap- plying this reduction test for arsenicum. The stannous is converted to stannic salt during the reaction. Distinction between Arsenious and Arsenic combinations . — The above tests are those of arsenicum, whether existing in the arse- nious or arsenic condition, though from the latter the element is not generally eliminated so quickly as from the former. Of the following reactions, that with nitrate of silver at once distinguishes arsenious acid and other arsenites from arsenic acid and other arseniates.' Mem . — The exact nature of all these analytical reactions will be more fully evident if traced out by diagrams or equations. Sixth Analytical Reaction . — Through an acidified solu- tion of arsenic pass sulphuretted hydrogen ; a yellow pre- cipitate of sulphide of arsenicum or arsenious sulphide (AS2S3) quickly falls. Add an alkaline hydrate or sulphy- drate to a portion of the precipitate; it readily dissolves. The precipitate consequently’’ would not be obtained on passing sulphuretted hydrogen through an alkaline solu- tion of arsenic. To another portion of the precepitate, well drained, add strong hydrochloric acid ; it is insoluble, unlike sulphide of antimony. Note I. — The only other metal which gives a yellow sulphide in an acid solution by action of sulphuretted hydrogen is cadmium ; but this sulphide is insoluble in alkaline liquids. 152 THE METALLIC RADICALS Note II. — A trace of sulphide of arsenicum is sometimes met with in sulphur (distilled from arsenical pyrites). It may be detected by digesting the sulphur in solution of ammonia, filtering, and evapo- rating to dryness ; a yellow residue of sulphide of arsenicum is ob- tained if that substance be present. Seventh Analytical Reaction, — Through an acidified solu- tion of arsenic acid, or any other arseniate, pass sulphu- retted hydrogen ; a yellow precipitate of arsenic sulphide (As.^S-) slowly falls. This also is soluble in alkaline hy- drates and sulphydrates. Chemical Analogy of Sulphur and Oxygen . — The solubility of arsenious and arsenic sulphide in alkaline solutions is good evidence of the close chemical analogy between them and the corresponding oxygen compounds of arsenicum. The potassium arsenite and sulph- arsenite, arseniate and sulph-arseniate, have the composition repre- sented by the following formulae : — K3ASO3 K3ASS3 K3ASO4 KjAsS, ; and the corresponding ammonium and sodium salts have a similar composition : — GAmllS -h As.^S 3 = 2 Am 3 AsS 3 -j- SH.^S 6AmHS -f AS 2 S- = 2Am3AsS4 4- 3H.^S. Eighth Analytical Reaction, — To an aqueous solution of arsenic add two or three drops of solution of sulphate of copper, and then cautiously add diluted solution of ammo- nia, drop by drop, until a green precipitate is obtained. The production of this precipitate is characteristic of ar- senicum. To a portion of the mixture add an acid ; the precipitate dissolves. To another portion add alkali ; the precipitate dissolves. These two experiments show the advantage of testing a suspected arsenical solution by^ lit- mus paper before applying this reaction ; if acid, cautiously adding alkali, if alkaline, adding acid, till neutrality^ is obtained. (Or a special copper reagent may^ be used ; see a note to the Eleventh Analytical Reaction, p. 153.) The precipitate is arsenite of copper (Cu"HAs 03 ) or Scheele's Green, More or less pure, or mixed with acetate or, occasionally, carbonate of copper, it is very largely used as a pigment under many names, such as Brunswick Green and Schweinfurth (jreen,by painters, paper-stainers, and others. Ninth Analytical Reaction, — Apply the test just de- scribed to a solution of arsenic acid or other arseniate; a somewhat similar precipitate of arseniate of copper is obtained. ARSENICUM. 153 Tenth Analytical Reaction, — Repeat the eighth reaction, substituting nitrate of silver for sulphate of copper : in this case yellow arsenite of silver (AggAsO^) falls, also soluble in acids and alkalies. Eleventh Analytical Reaction, — Apply the test to a solu- tion of arsenic acid or other arseniate ; a c7ioco?a^e-colored precipitate of arseniate of silver (AggAsOJ falls. Copper and Silver Reagents for Arsenicum, — The last four reac- tions may be performed with increased delicacy and certainty of result, if the copper and silver reagents be previously prepared in the following manner ; To solution of pure sulphate of copper (about 1 part in 20 of water) add ammonia until the blue precipitate at first formed is nearly, but not quite, redissolved; filter and preserve the liquid as an arsenicum reagent, labelling it solution of ammonio- sidphate of ‘copper (B. P.). Treat solution of nitrate of silver (about 1 part in 40) in the same way, and label it solution of ammonio- nitrate of silver (B. P.). The composition of these two salts will be referred to subsequently. Arsenious and Arsenic Compounds. — While many reagents may be used for the detection of arsenicum, only nitrate of silver, as already stated, will readily indicate in which state of oxidation the arsenicum exists ; for the two sulphides and the two copper precipi- tates, though differing in composition, resemble each other in appear- ance, whereas the two silver precipitates differ in color as well as in composition. Soluble arseniates also give insoluble arseniates with barium, cal- cium, zinc, and some other metallic solutions. Antidote, — In cases of poisoning by arsenic or arsenical preparations, the most effective antidote is recently pre- cipitated moist ferric hydrate {Ferri Peroxidum Humidum^ B, P., Ferri Oxidum Hydratum,, U. S. P.). It is perhaps best administered in the form of a mixture of solution of perchloride of iron {Liquor or Tinctura) with carbonate of sodium — two or three ounces of the former to about one ounce of the crystals of the latter. Instead of the carbon- ate of sodium, about a quarter of an ounce of calcined mag- nesia may be used. These quantities will render at least 10 grains of arsenic insoluble. Emetics should also be given, and the stomach-pump applied as quickly as possible. The above statements regarding the antidote for arsenic may be verified by mixing the various substances together, filtering, and proving the absence of arsenicum in the filtrate by applying some of the foregoing tests. Mode of Action of the Antidote. — The action of the carbonate of sodium or the magnesia is to precipitate ferric hydrate (Fe^hHO) — chloride of sodium (NaCl) or magnesium (MgOl 2 ) being formed, 154 THE METALLIC RADICALS. which are harmless, if not beneficial, under the circumstances. The reaction between the ferric hydrate and the arsenic results in the formation of insoluble ferrous arseniate. 2(Fe,6HO) + As,0, = Fe 32 AsO, + -H Fe2HO Ferric Arsenic. Ferrous Water. Ferrous, hydrate. arseniate. hydrate. As already stated, dried ferric hydrate (then become an oxyhy- drate, Fe^0^4H0) Ferri Peroxidum Hydratum, B. P.) has no action on arsenic. Even the moist recently prepared hydrate (Fe.^GHO) ceases to react with arsenic as soon as it has become con- verted into an oxyhydrate (Fe^ 036 H 0 ), a change which occurs though the hydrate be kept under water (Procter). According to T. and H. Smith this decomposition occurs gradually, but in an in- creasing ratio ; so that after four months the power of the moist mass is reduced to one-half, and after five months to one-fourth. QUESTIONS AND EXERCISES. 249. "What is the formula of a molecule of arsenicum? 250. In what form does arsenicum occur in nature? 251. Describe the characters of white arsenic. 252. Name the official preparations of arsenicum. 253. What proportion of arsenic (AS 2 O 3 ) is contained in Liquor Arsenicalis, B. P., and Liquor Arsenici Hydrochloricus, B. P. ? 254. By what method may arsenic be reduced to arsenicum ? 255. Give the formulae of arsenious and arsenic acids and anhy- drides. 256. Explain, by diagrams, the reactions which occur in convert- ing arsenic into Arseniate of Sodium by the process of the British Pharmacopoeia. 257. Why is anhydrous instead of crystallized arseniate of sodium employed in the preparation of Liquor Sodce Arseniatis, B. P.? 258. In the preparation of Arseniate of Iron from ferrous sulphate and arseniate of sodium, why is acetate of sodium included ? 259. Describe the manipulations necessary in distinguishing arsenic by its crystalline form. 260. How is Reinsch’s test for arsenicum applied, and under what circumstances may its indications be fallacious ? 261. Give the details of Marsh’s test for arsenicum, and the pre- cautions to be observed in its performance. Explain the reactions by diagrams. 262. What peculiar value has Fleitmann’s test for arsenicum? 263. Describe the conditions under wdiich sulphuretted hydrogen becomes a trustworthy test for arsenicum. 264. IIow may a trace of sulphide of arsenicum be detected in sulphur ? 265. How are the salts of copper and silver applied as reagents for the detection of arsenicum ? 266. How are arsenites distinguished from arseniates? ANTIMONY. 155 267. Mention the best antidote in cases of poisoning by arsenic, explain the process by which it may be most quickly prepared, and describe its action. 268. What light does the action of arsenic on ferric hydrate throw on the constitution of the latter substance ? ANTIMONY. Symbol Sb (stibium). Atomic weight 122. Source and Uses, — Antimony occurs in nature chiefly as sulphide, Sb 2 S 3 . The crude or hlack antimony of pharmacy is this native sulphide freed from earthy impurities by fusion : it has a striated, crystalline, lustrous fracture ; subsequently powdered it forms the grayish-black crystalline Antimonium nigrum, B. P., Antimonii sulphuretum, U. S. P. The metal is easily obtained from the sul- phide by roasting, and then reducing with charcoal and carbonate of sodium. Metallic antimony is an important constituent of Type- metal, Britannia metal (tea and coflee pots, spoons, etc.), and the best varieties of Pevjter. The old pocula emetica, or everlasting emetic cups, were made of antimony ; wine kept in them for a day or two acquired a variable amount of emetic quality. The metal is not used in making the antimonial preparations of the Pharmaco- poeia, the sulphide alone being, directly or indirectly, employed for this purpose. Antimony has very close chemical analogies with arsenicum. Its atom, in the official salts, exerts trivalent activity (e. g., SbClg), but sometimes it is quinquivalent (e. g., SbClg). Reactions having (a) Synthetical and (5) Analytical Interest. {a) Reactions having Synthetical Interest. Chloride of Antimony. Antimonious Chloride. First Synthetical Reaction Boil half an ounce or less of sulphide of antimony with four or live times its weight of hydrochloric acid in a dish in a fume-chamber or the open air; sulphuretted hydrogen is evolved and solution of cliloride of antimony, SbCl^, obtained. Sb.,S3 4- 6HC1 = SSbCl^ + 3H,S Sulphide of Hydrochloric Chloride of Sulphuretted antimony. acid. antimony. hydrogen. This solution, cleared by subsidence, is what is commonly known as Butter of antimony [Liquor Antimonii Chloridi, B. P.). If pure sulphide has been used in its preparation the liquid is nearly colorless ; but much of that met with in veterinary pharmacy is simply a by-product in the generation of sulphuretted hydrogen from 156 THE METALLIC RADICALS. native sulphide of antimony and hydrochloric acid, and is more or less brown from the presence of chloride of iron. It not unfrequently darkens in color on keeping ; this is due to absorption of oxygen from the air and conversion of light-colored ferrous into dark-brown ferric chloride or oxychloride. True butter of antimony (SbCl,) is obtained on evaporating the above solution to a low bulk, and distilling the residue. The butter condenses (as a white crystalline semi-transparent mass in the neck of the retort ; at the close of the operation it may be easily melted and run down in a bottle, which should be subsequently well stoppered. Pentacliloride of antimony (SbClg), or antimonic chloride, is a fuming liquid, obtained on passing chlorine over the lower chloride. Oxychloride of Antimony. Antimonious Oxychloride. Second Synthetical Reaction. — Pour the solution of chlo- ride of antimony produced in the last reaction into several ounces of water ; a white precipitate of oxychloride of an- timony ( 2 SbCl 3 , bSh^^Og) falls, some chloride of antimony remaining in the supernatant acid liquid. This is the o\^ pulvis Algarothi, pidvis angelicus, or mercurius vitae. On standing under water it gradually becomes crystalline. 12SbCl3 + 15H,0 = 2SbCl3,5Sb,03 + 30HCI Chloride of Water. Oxychloride of Hydrochloric antimony. antimony. acid. Oxide of Antimony. Antimonious Oxide. Well wash the precipitate with water, by decantation {vide p. 93), and add solution of carbonate of sodium; the ♦ chloride remaining with the oxide is thus decomposed, and oxide of antimony (Sb.^Og) alone remains. This is Anti- monii Oxidum.^ B. P. and U. S. P. It is of a light bulf or grayish-white color, or quite white if absolutely free from iron, insoluble in water, soluble in hydrochloric acid, fusi- ble at a low red heat. The moist oxide of antimony may be well washed and employed for the next reaction, or dried over a water-bath. At temperatures above 212° oxygen is absorbed, and other oxides of antimony formed. The pre- sence of the latter is detected on boiling the powder in solution of acid tartrate of potassium, in which oxide of antimony (Sb^Og) is soluble, but antimonic anhydride (Sb^O.) and the double oxide or so-called antimonious an- hydride (Sb^Og) insoluble. t 2 SbCl 3 , 5 Sb ,03 + SNa^COg = -f GNaCl + SCO, Oxychloride of Carbouate Oxide of Chloride Carbonic ^antimony. of sodium. antimony. of sodium. acid gas. ANTIMONY. 15t The higher oxide of antimony (Sb 205 ), termed antimonic oxide or anhydride, corresponding with arsenic anhydride, is obtained on decomposing the pentachloride by water, or on boiling metallic anti- mony with nitric acid. The variety obtained from the chloride differs in saturating-power from that obtained from the metal, and is termed metantimonic acid meta, beyond.) Tartar Emetic. Third Synthetical Reaction — Mix the moist oxide of antimony obtained in the previous reaction with about an equal quantity of cream of tartar (6 of the latter to 5 of the dry oxide) and sufficient water to form a paste ; set aside for a day to facilitate complete combination ; boil the product with water, and filter; the resulting liquid contains the double tartrate of antimony and potassium (KSbC^H^Oy), potassio-tartrate of antimony, tartrated an- timony, or tartar emetic (emetic, from emeo^ I vomit ; tartar from Taprapo^, tartaros^ see Index). 2KHC,H,Og + SbA = 2KSbC,H,0, + H^O Acid tartrate Oxide of Tartar emetic. Water, of potassium. antimony. On evaporation the salt is obtained in colorless trans- parent triangular-faced crystals of the above composition, with a molecule of water of crystallization, forming the Antimonium Tartaratum^ B. P. (KSbC^H^O., H 2 O) the Antimonii et Potassii Tartras^ U. S. P. The formula for tartar emetic is apparently inconsistent with the general formula for tartrates R'R'C^H^Og); this will be subsequently fully explained in connection with Tartaric Acid. The salt appears to be an oxytartrate (KSbC,H,OgO). Tartar emetic is soluble in water, and slightly so in proof spirit. Dissolved in sherry wine it forms the official Vinum Antimoniale^ B. P., and Vinum Antimonii^ U. S. P. It may be externally applied as an ointment, Unguentum An- timonii Tartarati^ B. P. ( Unguentum Antimonii^ U. S. P.). Sulphurated Antimony. Oxysulphide of Antimony. Fourth Synthetical Reaction, — Boil a few grains of sul- phide of antimony with solution of soda (potash, U. S. P.) in a test-tube (or larger quantities in larger vessels, 10 ounces of sulphide to 4^ pints of the official solution of soda for 2 hours, frequently stirring, and occasionally re- placing water lost by evaporation), and filter; into the 14 158 THE METALLIC RADICALS. filtrate, before cool, stir diluted sulphuric acid until the liquid is slightly acid to test-paper; a brownish-red pre- cipitate of oxysulphide of antimony, the Antimonmm Sul- phuratum^ B. P. and U. S. P., falls ; filter, wash, and dry over a water-bath. It is a mixture of sulphide of anti- mony (Sb^Sg) with a small and variable amount of oxide (Sb.^Og). The oxide results from the double decomposition of sulphide of antimony and soda. Antimonii Oxy sulphur etum. — The United States Phar- macopoeia in another preparation orders carbonate of sodium instead of the caustic alkali, and directs that only that precipitate be retained which separates from the alka- line liquid on cooling. If a small quantity of sulphur be boiled with the sulphide of antimony in solution of soda, the precipitate on the addition of sulphuric acid will be bright orange-red, on account of the presence of a higher sulphide having a yellow color (Sb^S^). There are some of the many varieties of mineral Tcerines, so called from their similarity in color to the insect kermes. Kermes is the name, now obsolete, of the Coccus llicis, a sort of cochineal-insect, fall of reddish juice, and used for dyeing from the earliest times. Explanation of process . — The sulphides and oxides of antimony, • like those of arsenicum, react with the sulphides and oxides of cer- tain metals to form soluble salts (Na^SbSg and Na^SbOg). 2 Sb,S 3 + 6NaHO = 2Na3SbS3 -+- Sb.O^ + 3H,0 Sulphide of Soda. Sulph-antimonite Oxide of Water. antimony. of sodium. antimony. Sb,,0, + 6NaH0 = 2 Na 3 Sb 03 + SH.^O Oxide of Soda. Antimonite Water, antimony. of sodium. In the hot solutions of these salts sulphide and oxide of antimony arc soluble, and are reprecipitated in an indefinite state of combina- tion, partially, on cooling, or wholly on the addition of acid. The acid also decomposes the oxysalt with precipitation of oxide, and the sulphur-salt with precipitation of orange sulphide of antimony. The acid is added to the liquid before much oxysulphide has deposited (that is, before the solution is cool), in order to insure uniformity of product. 2 Na 3 SbS 3 4- SH^SO^ = 3Na,SO, + Sb.Sg + 3H,S Sulph-autimonite Sulphuric Sulphate of Sulphide of Sulphuretted of sodium. acid. sodium. antimony. hydrogen. 2 Na 3 Sb 03 + 3H2SO4 = 3 NajSOi + Sb^Oj + 3H3O Antimonite Sulphuric Sulphate Oxide of Water. of sodium. acid. of sodium. antimony. The oxide and sulphide mentioned in these equations, together with excess of sulphide of antimony originally dissolved by the alkaline ANTIMONY. 159 liquid, are all precipitated when the acid is added, and form the Sul- phurated Antimony of the Pharmacopoeia, ‘‘ an orange-red powder, readily dissolved by caustic soda, also by hydrochloric acid with the evolution of sulphuretted hydrogen and the separation of a little sul- phur.” Its antimony is detected by dissolving the precipitate in hydrochloric acid, or in solution of acid tartrate of potassium, and passing sulphuretted hydrogen through the liquid, as described in the first analytical reaction. These four synthetical reactions illustrate the official processes for the respective substances. The solution of chloride of antimony is only used in the preparation of oxide ; the oxide, besides its use in the preparation of tartar emetic, is mixed with twice its weight of phosphate of calcium (purified bone-earth) to form Pulvis Anti- monialis, B. P. The sulphides and hydride of antimony are incidentally men- tioned in the following analytical paragraphs. (6) Reactions having Analytical Interest {Tests). First Analytical Reaction. — Through an acidified anti- monial solution pass sulphuretted hydrogen; an orange precipitate of amorphous sulphide of antimony falls. It has the same composition as the crystalline black sulphide (Sb.^S 3 ), into which, indeed, it is quickly converted by heat. Like sulphide of arsenicum, it is soluble in alkaline solu- tions. Collect a portion on a filter and, when well drained, add hydrochloric acid ; it dissolves — unlike sulphide of arsenicum. A higher sulphide of antimony (Sb^S^) corresponding to the higher sulphide of arsenicum, exists. It is formed on passing sulphuretted hydrogen through an acidified solution of the higher chloride (SbCL), or on boiling black sulphide of antimony and sulphur with an alkali, and decomposing the resulting filtered liquid by an acid. Note . — The arsenious and antimonious compounds only are em- ployed in medicine. The arseniates and antimoniates are sometimes useful in analysis, and the antimonic chloride in chemical research. The higher compounds of both elements are noticed here chiefly to draw attention to the close analogy existing between arsenicum and antimony, an analogy carried out in the numerous other compounds of these elements. Second Analytical Reaction. — Dilute two or three drops of the solution of chloride of antimony with water ; a pre- cipitate of oxychloride occurs, the formation of which has 160 THE METALLIC RADICALS. been explained under the similar synthetical reaction. The occurrence of this precipitate distinguishes antimony from- arsenicum, but is a reaction that cannot be fully relied upon in analysis, because requiring the presence of too much material and the observance of too many conditions. Add a sufficient quantity of hydrochloric acid to dissolve the precipitate, and boil a piece of copper in the solution as directed in the corresponding test for arsenicum {vide page 148) ; antimony is deposited on the copper. Wash, dry, and heat the copper in a test-tube as before ; the anti- moii}^, like the arsenicum, is volatilized off the copper and condenses on the side of the tube as white oxide, but the sublimate, from its low degree of volatility, condenses close to the copper, and, moreover, is destitute of crystalline character, is amorphous (a, a, without ; morphe^ shape). Shake out the copper and boil water in the tube for several minutes. Do the same with the arsenical subli- mate similarly obtained. The deposit of arsenic slowly dissolves, and may be recognized in the solution by ammonio-nitrate of silver; the antimonial sublimate is insoluble. Third Analytical Reaction , — Perform the experiments described under Marsh’s test for arsenicum (pp. 149, 150), carefully observing all the details there mentioned, but using a few drops of solution of chloride of antimony or tartar emetic instead of the arsenical solution. Anti- moniuretted hydrogen, or hydride of antimony (SbHg), is formed and decomposed in the same way as arseninretted hydrogen. To one of the arsenicum spots on the porcelain lid (p. 149) add a drop of solution of “chloride of lime” (bleach- ing-powder) ; it quickly dissolves. Do the same with an antimony spot ; it is unaffected. Heat more quickly causes the volatilization of an arsenicum than an antimony spot ; sulphydrate of ammonium more readily dissolves the antimony than the arsenicum. Boil water for several minutes in the beaker or wide * test-tube containing the arsenious sublimate (page 150) ; it slowly dissolves and may be recognized in the solution by the yellow precipitate given on the addition of solution of ammonio-nitrate of silver. The antimonial sublimate, similarly^ treated, gives no corresponding reaction. ANTIMONY. IGl Pass a slow current of sulphuretted hydrogen through ""the delivery-tube removed from the hydrogen-apparatus (page 150), and, when the air may be considered to have been ejxpelled from the tube, gently heat that portion con- taining the deposit of arsenicum ; the latter will be con- verted into a yellow sublimate of sulphide of arsenicum. Remove the tube from the sulphuretted-hj^drogen appa- ratus, and repeat the experiment with a similar antimony deposit; it is converted into orange sulphide of antimony, which, moreover, owing to inferior volatility, condenses nearer to the flame than sulphide of arsenicum. Pass dry hydrochloric acid gas through the two de- livery-tubes. This is accomplished by adapting first one tube and then the other by a cork to the test-tube contain- ing a few lumps of common salt, on which a little sulphuric acid is poured during the momentary removal of the cork. The sulphide of antimony dissolves and disappears; the sulphide of arsenicum is unaffected. Thorough perception of the chemistry of arsenicum and anti- mony will he obtained on constructing equations or diagrams descriptive of each of the foregoing reactions. Antidote — The introduction of poisonous doses of anti- monials into the stomach is fortunately quickly followed by vomiting. If vomiting has not occurred, or apparently to an insufficient extent, any form of tannic acid may be administered (infusion of tea, nutgalls, cinchona, oak-bark, or other astringent solutions or tinctures), an insoluble tannate of antimony being formed, and absorption of the poison consequently somewhat retarded. The stomach- pump must be as quickly as possible applied. Recently precipitated moist ferric hydrate is also, ac- cording to T. and H. Smith, a perfect absorbent of anti- mony from its solutions, the chemical actions being probably, they say, similar to that which takes place between ferric hydrate and arsenious anhydride. It may be given in the form of a mixture of perchloride of iron with either carbo- nate of sodium or magnesia. These statements may be verified by mixing together the various substances, filtering, and testing the filtrate for antimony in the usual manner. 14 * 162 THE METALLIC RADICALS. DIRECTIONS FOR APPLYING THE FOREGOING REACTIONS TO THE ANALYSIS OF AN AQUEOUS SOLUTION OF SALTS OF ONE OF THE ELEMENTS ArSENICUM AND ANTIMONY. Acidify the liquid with hydrochloric acid, and pass through it sulphuretted hydrogen: — A yellow precipitate indicates arsenicum. An orange precipitate indicates antimony. The result may be confirmed by the application of other tests. DIRECTIONS FOR APPLYING THE FOREGOING REACTIONS TO THE ANALYSIS OF AN AQUEOUS SOLUTION OF SALTS OF BOTH Arsenicum and Antimony. Acidify a small portion of the liquid with hydrochloric acid, and pass througli it sulphuretted hydrogen. Note I. If the precipitate by sulphuretted hydrogen is unmis- takably orange, antimony may be put down as present, and arseni- cum only further sought by the application of Fleitmann’s test to the solution of the sulphides in aqua regia* freed from sulphur by boiling, or, better, to the original solution. Note II. Sulphide of antimony is far less readily soluble than sul- * phide of arsenicum in solution of carbonate of ammonium. But this fact possesses limited analytical value ; for the color of the sulphides is already sufficient to distinguish the one from the other when they are unmixed ; and when mixed, much sulphide of antimony will pre- vent a little sulphide of arsenicum from being dissolved by the alka- line carbonate, while much sulphide of arsenicum will carry a little sulphide of antimony into the solution. When the proportions are, apparently, from the color of the precipitate, less wide, solution of carbonate of ammonium will be found useful in roughly separating the one sulphide from the other. On filtering and neutralizing the alkaline solution by an acid, the yellow sulphide of arsenicum is reprecipitated. The orange sulphide of antimony will remain on the filter. Note III. Solution of bisulphite of potassium is said by Wohler to be a good reagent for separating the sulphides of arsenicum and antimony, the former being soluble, the latter insoluble in the liquid. Note IV. Another reagent for separating the sulphides of arse- nicum and antimony is strong hydrochloric acid. As little water as possible must be present. On boiling, the sulphide of antimony dis- solves, while the sulphide of arsenicum remains insoluble. The liquid * Aqua regia is a mixture of two parts hydrochloric and one part nitric acid. It was so called, from its property of dissolving gold, the “ king” of metals. ARSENICUM AND ANTIMONY. 163 slightly diluted, filtered, more water added, and sulphuretted hydro- gen again transmitted, gives orange sulphide of antimony. The pro- cess should previously be tried on the precipitated mixed sulphides. The presence of arsenicum may be confirmed by the application of Fleitmann’s test to the original solution. Note Y. If the precipitate by sulphuretted hydrogen is unmis- takably yellow, arsenicum may be put down as present, and any antimony detected by the previous or one of the following two pro- cesses. These two processes are rather long, and require much care in their performance, but are useful, because a small quantity of antimony in much arsenicum, or vice versa, may be detected by their means. First Process , — Generate hydrogen and pass it through a small wash-bottle containing solution of acetate of lead, to free the gas from any trace of sulphuretted hydrogen it may possess, and then through a dilute solution of nitrate of silver contained in a test-tube. When the apparatus is in good working order, pour into the generating-bottle the solution to be examined, adding it gradually to prevent violent action. After the gas has been passing for five or ten minutes, examine the contents of the nitrate-of-silver tube ; arsenicum, if present, will be found in the solution in the state of arsenious acid, AsUg -|- -j- GAg^Og = IlgAsOg -h GIINOg “h 3 Ag2 5 while antimony, if present, will be found in the black precipitate that has fallen, according to the following equation : — SbHg -f 3AgN03 = SbAg 2 + 3 HNO 3 . The arsenious radical may be detected in the clear, filtered, supernatant liquid, which still contains much nitrate of silver, by cautiously neutralizing with a very dilute solution of ammonia, or by adding a few drops of solution of ammo- nio-nitrate of silver, yellow arsenite of' silver being pro- duced. The antimony may be detected by washing the black precipitate, boiling it in an open dish with solution of tartaric acid, filtering, acidulating with hydrochloric acid, and passing sulphuretted hydrogen through the solu- tion — the orange sulphide of antimony being precipitated (Hofmann). Second process , — Obtain the metallic deposit in the mid- dle of the delivery-tube as already described under Marslds test. Act on the deposit by sulphuretted hydrogen gas, and then by hydrochloric acid gas as detailed in the third ICA THE METALLIC RADICALS. analytical reaction of antimony (p. 160). If both arseni- cnm and antimony are present, the deposit, after the action of sulphuretted hydrogen, will be found to be of two colors, the yellow sulphide of arsenicum being usually further removed from the heated portion of the tube than the orange sulphide of antimony. Moreover, subsequent action of hydrochloric acid gas causes disa'ppearance of the antimonial deposit, which is converted into chloride of antimony and carried off in the stream of gas. The chief objection to this process is the liability of the operator mistaking sulphur, deposited from the sulphuretted hydrogen gas by heat, for sulphide of arsenicum. But the presence or absence of arsenicum is easily confirmed by applying Fleitmann’s test to the original solution, while the process is most useful for the detection of a small quantity t)f salt of antimony when mixed with much arse- nical compounds. The laboratory student may now proceed to the analysis of aqueous solutions of salts of any of the metallic elements hitherto considered. The method followed may be that for the separation of the previous three groups, sulphuretted hydrogen being first passed through the solution to throw out arsenicum and antimony. The whole scheme of analysis is given on the next page. Three or four solutions should be examined fcfore proceeding to the last group of metals. Learners w'ho have no opportunity of working at practical analysis will gain much knowledge by endeavoring not to remember, but to understand these methods of separating elements from each other in a solution containing several compounds. 165 AUSENICUM AND ANTIMONY. * It is not usually necessary to add NH^Cl, the HCl with some of the NH^HO commonly giving sufficient NH^Cl. t Much time may sometimes be saved by carefully remembering the color of the various hydrates and sulphides precipitated. Thus, if the AmHS precipitate is white, iron cannot be present, and AniHO, for A1 and Zn maybe at once added to the hydrochloric solution of the precipitate. The group-tests in this table are H 2 S, AmHS, and Am2C02. 16G THE METALLIC RADICALS. QUESTIONS AND EXEEGTSES. 269. What is the composition and source of the Black Antimony of pharmacy? 270. In what alloys is metallic antimony a characteristic in- gredient ? 271. What is the quantivalence of antimony as far as indicated by the formulae of the official preparations ? 272. By a diagram show how “Butter of Antimony” is prepared. 273. Write out equations or diagrams expressive of the reactions which occur in converting chloride of antimony into oxide. 274. What is the formula of Tartar Emetic? 275. Explain the official process for the preparation of Oxysul- phide of Antimony [Antimonium Sulphuratum, B. P.) by aid of diagrams. 276. Give a comparative statement of the tests forarsenicum and antimony. 277. How is antimony detected in the presence of arsenicum? 278. How may arsenicum and iron be distinguished analytically? 279. Describe a method by which antimony, magnesium, and iron may be separated from each other. 280. Draw out an analytical chart for the examination of an aqueous liquid containing salts of arsenicum, zinc, calcium, and ammonium. COPPER, MERCURY, LEAD, SILVER. These metals, like arsenicum and antimony, are precipitated from acidified solutions by sulphuretted hydrogen, in the form of sulphides ; but the sulphides, unlike those of arsenicum and antimony, are in- soluble in alkalies. The atom of copper is usually bivalent, Cu” ; mercury bivalent in the mercuric salts, Hg", and univalent in the mercurous salts, Hg'; lead sometimes quadrivalent, Pb"", but generally exerting only bivalent activity, Pb" ; and silver univalent, Ag'. COPPER. Symbol Cu. Atomic weight 63.5. Source . — The commonest ore of this metal is copper pyrites, a double sulphide of copper and iron, raised in Cornwall ; Australia and Russia supply malachite, a mixed carbonate and hydrate; much ore is also imported from South America. It is smelted in enor- mous quantities at Swansea, South Wales, a locality peculiarly fitted for the operation on account of its proximity to the coal-fields, and its position as a sea-coast town — these advantages at all times insuring cheap fuel and freightage to the different metallurgical establishments. COPPER. 16T Alchemy. — The alchemists termed this metal Venus, perhaps on account of the beauty of its lustre, and gave it her symbol a compound hieroglyphic also indicating a mixture of gold © and a certain hypothetical substance called acrimony the corrosive na- ture of which was symbolized by the points of a Maltese cross. To this day the blue show-bottle in the shop-window of the pharmacist is occasionally ornamented by such a symbol, indicative, possibly, of the fact that the blue liquid in the vessel is a preparation of copper. Coinage . — The material of British copper coinage is now a bronze mixture composed in 100 parts by weight of 95 copper, 4 tin, and 1 zinc, the same as in the copper coinage of France. The penny is coined at the rate of 48 pence in one pound avoirdupois, of 7000 grains, or 453.6 grammes ; the halfpenny at 80 in the pound avoirdu- pois, and the farthing at 160. British bronze coins are a legal tender in payments to the amount of Is. Metallic Copper ( Cuprum, B. P. and IT. S. P.) in the form of fine wire, about No. 25, is used in preparing Spiritus ^theris Nitrosi, B. P. and U. S. P. Copper Foil, B. P., is “ pure metallic copper, thin and bright.” Quantivalence . — Copper forms two classes of salts ; in one the atom is bivalent (Cu"), in the other exerts univalent activity (CU 2 "). The former are of primary importance, the latter being for the most part unstable and wanting in technical interest. Their compounds are distinguished as cupric and cuprous ; but those of the higher class only have general interest, and will be almost exclusively alluded to in the following paragraphs. Cuprous iodide (CU 2 I 2 ) will subsequently be referred to as a convenient form in which to remove iodine from solution, and the formation of cuprous oxide (CU 2 O), under given circumstances, as an indicator of the presence of sugar in a liquid. Reactions having (a) Synthetical and (b) Analytical Interest. (a) Synthetical Reactions. The processes for the following salts include the only synthetical copper-reactions having any medical or phar- maceutical interest: 1, cupric oxide, the black oxide of copper, by heating a piece of copper to low redness on a piece of earthenware 'in an open fire ; 2, cupric sulphate, the common sulphate of copper, by boiling black oxide of copper and about an equal weight of sulphuric acid in water, filtering, and setting aside the solution so that crystals may form on cooling ; and, 3, the preparation of solution of ammonio-sulphate of copper (see p. 153 ; also p. 168). 168 THE METALLIC RADICALS. Cu, + Oj = 2CuO Copper. Oxygen. Cupric oxide. CuO + H,SO, z= CuSO, + H.p Cupric Sulphuric Cupric Water. oxide. acid. sulphate. Sulphate of Copper [Cupri Sulphas, B. P. and U. S. P.) (CUSO4, 5H2O), blue vitriol, hluestone, or cupric sulphate, is the only copper salt of much importance in Pharmacy. It is a by-product in silver- refining (2Ag2S04 + Cu2 = 2CUSO4 + 2Ag2). It is also formed by roasting copper pyrites. In the latter operation the sulphide of iron and sulphide of copper are oxidized to sulphates ; but the low red heat employed decomposes the sulphate of iron, w^hile the sulphate of copper is unaffected ; it is purified by crystallization from a hot aqueous solution, though frequently much sulphate of iron remains in the crystals. Sulphate of copper results on 'dissolving in diluted sulphuric acid the black oxide (CuO) obtained in annealing copper plates ; it may also be prepared by boiling copper with three times its^weight of sulphuric acid (2H2SO4+ Ou = CUSO4+ SO2+ 2H2O), diluting, filtering, evaporating, and crystallizing. Anhydrous Sulphate of Copper (CUSO4), is a yellowish-white powder prepared by depriving the ordinary blue crystals of sulphate of copper of their water of crystallization by exposing to a tempera- ture of about 400 ^ F. It is used in testing alcohol and similar liquids for water, becoming blue if the latter be present. Verdigris (from verde-gris, Sp. green-gray) is a Subacetate ( Cu~ pri Subacetas, U. S. P.) or Oxyacetate of Copper (B. P.) (CU2O2C2 H3O2), obtained by exposing alternate layers of copper and ferment- ing refuse grape-husks to the action of air. Digested with twice its weight of acetic acid and a little water, the mixture being evaporated to dryness and the residue dissolved in water, it forms the official Solution of Acetate of Copper (CU2C2H3O2). The modes of forming cupric sulphide, hydrate, oxide, f error cyanide, and arsenite, as well as the precipitation of metallic copper, are incidentally alluded to in the following analytical paragraphs. (6) Reactions having Analytical Litere^ (Tests.) First Analytical Reaction . — Pass sulphurofeecl hydrogen through an acidified solution of a copper (sulphate, for example) ; black cupric sulphide (OuS)'fa^t Second Analytical Reaction . — Add sulpM^ftte of am- monium to an aqueous copper solution ; cut fgK^ ulphide is again precipitated, insoluble in ex(^es^. Note. — Cupric sulphide is not altogether insolublj^^fculphydratc of ammonium if free ammonia or nuich aniihoniatedlfiBbe present; it is quite insoluble in the fixed alkaline)siiiphides. Third Analytical Reaction. — Imii^’se a pi® of iron or steel, such as the point of a penlpii^mr a piewof wire, in I COPPER. 169 a few drops of a copper solution ; the copper is deposited, : of characteristic color, an equivalent quantity of iron > passing into solution. I By this reaction copper may be recovered on the larger scale from ; waste solutions, old hoop or other scrap iron being thrown into the I liquors. I Fourth Analytical Reaction. — Add ammonia to a cupric i solution; cupric hydrate (Cu2HO) of a light-blue color is I precipitated. Add excess of ammonia ; the precipitate is redissolved, forming a blue solution of ammonio-salt of I copper, so deep in color as to render ammonia an exceed- I ingly delicate test for this metal, i j An ammonio-sulphate of copper may be obtained in large crystals by adding strongest solution of ammonia to powdered sulphate of copper until the salt is dissolved, placing the liquid in a test-glass or cylinder, cautiously pouring in twice its volume of strong alcohol or methylated spirit, taking care that the liquids do not become mixed tying over the vessel with bladder, and setting aside for some weeks in a cool place. ( Wittstein.) The constitution of ammonio-sulphate I and other ammonio-salts of copper and coresponding salts of silver will be alluded to in connection with “ white precipitate,” the official “ ammoniated mercury.” Cuprum Ammoniatum, U. S. P,, is an ammonia-sulphate of cop- per prepared by rubbing together sulphate of copper and carbonate 01 ammonium until effervescence ceases, and drying the product. Fifth Analytical Reaction,— AM solution of potash or ! soda to a cupric solution ; cupric hydrate (Cu2H0) is pre- jcipitated, insoluble in excess. Boil the mixture in the 1 test-tube j the hydrate is decomposed, losing the elements ; of water, and becoming the black anhydrous oxide (CuO). ^ Sixth Analytical Reaction, — Add solution of ferrocyanide I of potassium (K^Fcy) to an aqueous cupric solution; a I reddish-brown precipitate of cupric ferrocyanide (Cu Fey) I falls. This also is a delicate test for cojDper. I Seventh Analytical Reaction, — To a cupric solution add : solution of arsenic, and cautiously neutralize with alkali • green cupric arsenite (CuHAsOg) falls. ’ Note. This precipitate has been already mentioned under arseni- cuni. An arsenicum salt is thus a test for copper, as a copper salt IS tor arsenicum— a remark that may obviously be extended to most analytical reactions ; for the body acted upon characteristically by ■a reagent ts as good a test for the reagent as the reagent is for it ; 'search I’^^gent when the other body is the object of 15 no THE METALLIC RADICALS. Antidotes . — In cases of poisoning by compounds of cop- per, iron filings should be administered, the action of which has just been explained (see third analytical reaction). Ferrocyanide of potassium may also be given (see sixth anal3^tical reaction). Albumen forms, with copper, a com- pound insoluble in water ; hence raw eggs should be swal- lowed, vomiting being induced or the stomach-pump applied as speedily as possible. QUESTIONS AND EXERCISES. 281. What are the relations of copper, mercury, lead, and silver to each other and to arsenicum and antimony ? 282. Name the sources of copper. 283. What proportion of copper is contained in English and French copper” coins ? 284. Give diagrams showing how Sulphate of Copper is prepared on the small and large scales. 285. Work out a sum showing how much Crystallized Sulphate of Copper may be obtained from 100 parts of sulphide ? — Ans. 26 I 5 . 286. How may Oxide of Copper be prepared ? 287. Mention the formula of Verdigris. 288. Name a good clinical test for copper. 289. What is the analytical position of copper ? 290. Mention the chief tests for copper. 291. How may copper be separated from arsenicum ? 292. Why is finely divided iron an effective antidote in cases of poisoning by copper ? MERCURY. Symbol Hg. Atomic weight 200. Molecular weight 200 {not double the atomic weight). Source . — Mercury occurs in nature as sulphide (HgS), forming the ore cinnabar (an Indian name expressive of something red), and is obtained from Spain, California, Eastern Hungary, China, Japan, and Peru. Preparation . — The metal is separated by roasting off the sulphur and then distilling, or distilling with lime, which combines with and retains the sulphur. Properties . — Mercury {Hydrargyrum, B. P. and U. S. P.) is a silver-white lustrous metal, liquid at common temperature. It boils at 662^ F., and at — 40^ F. solidifies to a malleable mass of octahedral crystals. When quite free from other metals it does not tarnish, and MERCURY. in its globules roll freely over a sheet of white paper without leaviug any streak or losing their spherical form. Formula . — The formula of the mercury molecule is Hg and not Hg.^, because at all ordinary temperatures two volumes, which if hydrogen would weigh two parts (H 2 ) or oxygen thirty-two parts (O 2 ), in the case of mercury vapor weigh only two hundred parts (Hg) ; that is, only once the atomic weight, not twice. That 200, and not 100, is the atomic weight of mercury is shown by the fact that 200 is the minimum proportion relative to 1 of hydrogen in which mercury combines, and by its relations to heat. Still it is difficult to imagine an atom existing in the free state in nature ; and the suggestion has been made that (as is proved to be the case with sulphur) mercury, as we know it, is in abnormal condition, and that if the weight of its vapor could be taken at a low temperature or under some other condition, its molecular weight might be found to be 400. Similar remarks may be made respecting zinc, the molecular weight of which, so far as we know, is identical with its atomic weight. Medicinal Compounds. — The compounds of mercury used in medicine are all obtained from the metal. The metal itself, rubbed with chalk or with confection of roses and powdered liquorice-root, or wdth lard and suet, until globules are not visible to the unaided eye, is often used in medicine. The preparations are : the Hydrar- gyrum cum Greta, B. P. and IT. S. P., or “ Gray Powder f Pilula Hydrargyri, B. P. and U. S. P., or “ Blue Pill and Unguentum Hydrargyri, B. P. and U. S. P., or “ Blue Ointment.” There are also a Compound Ointment, a Plaster of Mercury, a Plaster of Am moniacum and Mercury, a Liniment, and a Suppository. Their therapeutic effects are probably due to the black and red oxide which occur in them through the action of the oxygen of the air on the finely-divided metal. The proportion of oxide or oxides varies according to the age of the specimen. Mercurous and Mercuric Compounds.’ — Mercury combines wdth other elements and radicals in two proportions : those compounds in which the other, acidulous, radicals are in the lesser amount are termed mercurous, the higher being mercuric. Thus, calomel (HgCl)* is mercurous chloride, while corrosive sublimate (HgCh^) is mercuric chloride. In every pair of mercury compounds the mercu- ric contains twice as much complementary radical, in proportion to the mercury, as the mercurous. Note on Nomenclature. — The remarks made concerning the two classes of iron salts, ferrous and ferric (p. 120), apply in the main to the two series of mercury salts. The latter are systematically dis- tinguished in most modern works by the terms mercurous and mer- curic. In the British and United States Pharmacopoeias, however, which include only a few in comparison with the whole number of mercury salts, older and more strongly contrasted names are em- ployed, thus : — * The specific gravity of the vapor of calomel, and the fact that the salt is not decomposed at the temperature at which its specific gravity is taken, show that the formula of calomel is HgCl, and not Hg.^CI^. 172 THE METALLIC RADICALS. Systematic names. Official names. Mercurous iodide Mercuric iodide . Mercurous nitrate Mercuric nitrate Green iodide of mercury, Eed iodide of mercury. Not mentioned in 13. F. Nitrate of mercury. Mercuric sulphate Mercurous chloride Mercuric chloride Mercurous oxide Mercuric oxide . Mercurous sulphate Not mentioned in B. P. Sulphate of mercury. Subchloride of mercury. Perchloride of mercury. Black oxide of mercury. Red oxide of mercury. Specific Gravity . — Mercury is 13.6 times as heavy as water. Amalgams . — The compound formed in fusing metals together is usually termed an alloy [ad and ligo, to bind) ; but if mercury is a constituent, an amalgam [jxdxayya malagma, from malasd, to soften, the presence of mercury lowering the melting point of such a mixture). Most metals, even hydrogen, according to Leow, form amalgams. Reaction having (a) Synthetical and (6) Analytical Interest. (a) Synthetical Reactions. The Two Iodides. First Synthetical Reaction. — Rub together a small quan- tity of mercuiy and iodine, controlling the rapidity of com- bination by adding a few drops of spirit of wine, which, by evaporation, carries off heat, and thus keeps down tempera- ture. The product is either mercuric iodide, mercurous iodide, or a mixture of the two, as well as mercury or iodine if excess of either has been emplo 3 ^ed. If the two elements have been previously weighed in single atomic proportions, 200 of mercury to 127 of iodine (about 8 to 5, or 1 ounce of mercury to 278 grains of iodine), the mercu- rous or green (grayish-green) iodide results (Hgl [Hy- drargyri lodidum Viride., B. P. and U. S. P.) ; if in the proportion of one atom of mercury to two atoms of iodine (200 to twice 127, or about 4 to 5), the mercuric or red iodide, Hglg, results, an iodide that is also official, but made in another yvsiy. (See page 174.) The green iodide should be made and dried (without heat) with as little exposure to light as possible. Mercurous iodide is decomposed slowly by light, and quickly by heat, into mercuric iodide and mercury. Mercuric iodide occurring as an impurity in mercurous iodide may be detected by digesting in MERCURY. 173 ether (in which mercurous iodide is insoluble), filtering and evapo- rating to dryness ; mercuric iodide remains. Mercuric iodide is stable, and may be sublimed in scarlet crystals without decomposi- tion. (For details of the method by which a specimen of the crystals may be obtained, and the precautions to be observed, vide “ corro- sive sublimate,’^ p. 176.) Relation of Mercuric Iodide to Light. — In condensing, mercuric iodide is at first yellow, afterwards acquiring its characteristic scar- let color. This may be shown by smearing or rubbing a sheet of white paper with the red iodide, and then holding the sheet before a fire or over a flame for a few seconds. As soon as the paper becomes hot the red instantly changes to yellow, and the salt does not quickly regain its red color, even when cold, if the paper is carefully handled. But if a mark be made across the sheet by anything at hand, or the salt be pressed or rubbed in any way, the portions touched immedi- ately return to the scarlet condition. According to Warington, this change is consequent upon rhomboidal crystals being converted into octahedra with a square base, and will serve as an excellent illustration of the influence of physical structure in causing color. The yellow modification so acts on the rays of white light shining on its particles as to absorb the violet and reflect the complementary hue, the yellow, which, entering the eye of the observer, strikes his retina, and thus conveys to the brain the impression of yellowness ; and the red modification, though actually the same chemical sub- stance, is sufficiently different in the structure of its particles to absorb the green constituent of white light and reflect the comple- mentary ray, the red. Illustration of the Chemical law of Midtiple Proportions (p. 42). — Applying the atomic theory to the above iodides, it will at once be apparent why mercury and iodine should combine in the proportion of 200 of mercury with either 127 or 254 of iodine, and not with any intermediate quantity. For it is part of that theory that masses are composed of atoms, and that atoms are indivisible ; and that the weight of the atom of mercury is to that of iodine as 200 is to 127. Mercury and iodine can only combine, therefore, in atomic propor- tions, atom to atom (which is the same as 200 to 127), or one atom to two atoms (which is the same as 200 to 254). To attempt to com- bine them in any intermediate proportion would be useless, a mere mixture of the two iodides would result. A higher proportion of mercury than 200 to 127 of iodine gives but a mixture of mercurous iodide and mercury ; a higher proportion of iodine than 254 to 200 of mercury gives but a mixture of mercuric iodide and iodine. Or, for example, 200 grains of mercury, mixed with, say, 200 of iodine, would yield 139 grains of mercurous iodide, and 261 grains of mer- curic iodide ; for the 200 grains of mercury uniting with 127 grains of the iodine gives, for the moment, 327 grains of mercurous iodide and 73 grains of iodine still free. The 73 grains of iodine will im- mediately unite with 188 grains of the mercurous iodide (for if 127 of I require 327 of Hgl to form Hgl.^, 73 will require 188), and form 261 grains of mercuric iodide, diminishing the 327 grains of mercu- rous iodide to 139 grains. 15 * n4 THE METALLIC RADICALS. Preparation of Red Iodide of Mercury by precipitation. — To a few drops of a solution of a mercuric salt (corrosive sublimate, for example), add solution of iodide of potas- sium, drop by drop ; a precipitate of mercuric iodide, Hgl.^, forms, and at first quickly redissolves, but is permanent when sufficient iodide of potassium has been added. Con- tinue the addition of iodide of potassium; the precipitate is once more redissolved. Note. — When first precipitated, mercuric iodide is yellowish-red, but soon changes to a beautiful scarlet. Its solubility either in solu- tion of the mercuric salt or in solution of iodide of potassium renders the detection of a small quantity of a mercuric salt by iodide of potassium, or a small quantity of an iodide by a mercuric solution, difficult, and hence lessens the value of the reaction as a test. But the reaction has synthetical interest, the method by precipitation being that adopted in the British and United States Pharmacopoeias [Hydrargyri lodidum Rubrum,^. P. and U. S. P.). Mercuric iodide thus made has the same composition as that prepared by direct com- bination of its elements. Equivalent proportions of the two salts must be used in making the preparation (HgCl 2 = 271 ; 2KI = 332). About 4 parts of corrosive sublimate are dissolved in 50 or 60 of water (w^armth quickens solution) and 5 of iodide of potassium in 15 or 20 of water, the solutions mixed and the precipitate collected on a filter, drained, washed twice with distilled water, and dried on a plate over a water-bath. The mercury in mercuric or mercurous iodide is set free and sublimes in globules on heating either powder with dried carbonate of sodium in a test-tube ; the iodine may be detected by digesting with solution of soda, filtering, and to the solu- tion of iodide of sodium thus formed adding starch paste and acidu- lating with nitric acid, when blue iodide of starch results. HgCl^ -f 2KI = Hgl^ + 2KC1 Mercuric Iodide of Mercuric Chloride of chloride. potassium. iodide. potassium. Mercuric iodide is insoluble in water, slightly soluble in alcohol, tolerably soluble in ether. Precipitated red iodide of mercury mixed with white wax, lard, and oil, forms the Unguentum Hydrargyri lodidi Rubric B. P. and U. S. P. Donovan's Solution contained mercuric and arsenious iodides. The Two Nitrates. Second Synthetical Reaction. — Mix a little nitric acid in a test-tube with four or five times its bulk of water, add a small globule of mercury, and set the tube aside for a few hours, in a cool place ; solution of mercurous nitrate (llgXO.^) will be formed, and nitric oxide (NO) evolved. The solution may be retained for subsequent analytical operations. Hg3 + 4IINO3 = SIIgNO^ + 2 H ,0 -f NO. MERCURY. n5 Third Synthetical Reaction. — Place mercury in strong nitric acid, and warm the mixture; mercuric nitrate is formed, and will be deposited in crystals as the solution cools. Retain the product for a subsequent experiment. The mercuric nitrates vary somewhat in composition, according to the proportion, strength, and temperature of the acid used in their formation. A mercuric nitrate may be obtained having the formula Hg2N03. Hg3 + 8HNO3 = 3(Hg2N03) + 2N0 + 4H,0 Mercury. Nitric Mercuric Nitric Water, acid. nitrate. oxide. Mercuric Oxynitrates. — From the normal mercuric nitrate several oxynitrates may be obtained. Thus on merely evaporating a solu- tion of mercuric nitrate, and cooling, crystals having the formula Hg6036N03 are deposited. The latter, by washing with cold water, yield a yellow pulverulent oxynitrate, Hgs044N03 : mixed with lard, this has sometimes been used as an ointment. Boiled in water, the yellow gives a hrick-red oxynitrate, Hgg052N03. The Pharmacopoeial preparations of mercuric nitrate are Liquor Hydrargyri Nitratis Acidus, B. P. (sp. gr. 2.246 ; U. S. P., sp. gr. 2.165), and TJnquentum Hydrargyri Nitratis, B. P. and U. S. P. The former (B. P.) is made by placing four ounces of mercury in five fiuidounces of nitric acid diluted with an ounce and a half of water, and, when the metal is dissolved, boiling gently for fifteen minutes. The Two Sulphates. Fourth Synthetical Reaction. — Boil two or three grains of mercury with a few drops of strong sulphuric acid in a test-tube ; sulphurous acid gas (SO.J is evolved, and mer- curic sulphate {Hydrargyri Sulphas^ B. P.) (HgSOJ re- sults — a white heavy crystalline powder. Hg -h 2H,SO, = HgSO, + SO, + 2HO Mercury. Sulphuric Mercuric Sulphurous Water. Hcid. sulphate. acid gas. Between two and three ounces of mercuric sulphate may be prepared from a fluidrachm of mercury and a fluidounce of sulphuric acid boiled together in a small dish. These are the official proportions. The operation is completed and any excess of acid removed by evaporating the mix- ture of metal and liquid to dryness, either in the open air or in a fume-chamber, sulphuric acid vapors being exces- sively irritating to the mucous membrane of the nose and throat; dry crystalline mercuric sulphate remains. If residual particles of mercury are observed, the mass should be damped with sulphuric acid and again heated. 1Y6 THE METALLIC RADICALS. By-Products.-. — In clieniical manufactories, secondary products, such as the sulphurous gas of the above reaction, are termed by-pro- ducts, and, if of value, are utilized. In the present case the gas has no immediate interest, and is therefore allowed to escape. When very pure sulphurous acid gas is required for experiments on the small scale, this would be the best method of making it, a delivery- tube being adapted by a cork to the mouth of a flask containing the acid and metal. The sulphate of mercury would then become the by-product. Mercuric Oxy sulphate . — Water decomposes mercuric sulphate into a soluble acid salt and an insoluble yellow oxysulphate (Hg 302 SO4). The latter is called Turpeth mineral, from its resemblance in color to the powdered root of Ipomoea turpethum, an Indian sub- stitute for jalap. The yellow sulphate of mercury [Hydrargyri Sidphas Flava, U. S. P.) was formerly official in the pharmacopoeia of Great Britain, but is now seldom used. Fifth Synthetical Reaction. — Rub a portion of the dry mercuric sulpliate of the previous reaction with as much mercury as it alreadj' contains ; the product, when the two have thoroughly blended, is mercurous sulphate (Hg^SOJ: it may be retained for a subsequent experiment. Molecular Weight. — The exact proportion of mercury to sulphate is merely a matter of calculation ; for the combining proportion of a compound (if it possess any combining-power) is the sum of the com- bining proportions of its constituents. In other loords, the combin- ing iveight of a molecule is simply the sum of the weights of its constituent atoms, or, more generally, the molecular weight of a compound is the sum of the atomic weights of its elements. In accordance with this rule (sometimes called the fourth law of chemi- cal combination, though only a deduction from the first — p. 41), 296 of mercuric sulphate and 200 of mercury (about 3 to 2) are the exact proportions necessary to the formation of mercurous sulphate. The Two Chlorides. Sixth Synthetical Reaction. — Mix thoroughly^ a few grains of dry mercuric sulphate with about four-fifths its weight of chloride of sodium, and heat the mixture slowly^ in a test-tube in a fume-chamber or in the open air to leeward of the operator; mercuric chloride (IlgCl.^), or corrosive sublimate {Hydrargyri Perchloridum^ B. P., Hydrargyri Chloridum Cori'osivum^ U. S. P.), sublimes and condenses in the upper part of the tube in heavy color- less crystals or a cry^stalline mass. Somewhat larger quan- tities (in the proportion of 20 of sulphate to 16 of salt, and, vide infra., 1 of black oxide of manganese) may be sublimed in a pair of two-ounce or three-ounce round-bottomed galli- MERCURY. 17^ pots, the one inverted over tlie other, and the joint luted by moist fireclay (the powdered clay kneaded with water to the consistence of dough). The luting having been allowed to dry (somewhat slowly, to avoid cracks), the pots are placed upright on a sand-tray (plate-shape answers very well), sand piled round the lower and a portion of the upper pot, and the whole heated over a good-sized gas fiame for an hour or more. Red Iodide of Mercury and Calomel may be sublimed in the same way. The former requires less, the latter more, heat than corrosive subli- mate. HgSO, + 2NaCl = HgCl, + Mercuric Chloride of Mercuric Sulphate of sulphate. sodium. chloride. sodium. Note . — If the mercuric sulphate contain any mercurous sulphate, some calomel may be formed. This result will be avoided if 2 or 3 per cent, of black oxide of manganese be previously mixed with the ingredients, the action of which is to eliminate chlorine from the excess of chloride of sodium used in the process, the chlorine convert- ing any calomel into corrosive sublimate. Manganate of sodium and a lower oxide of manganese are simultaneously produced. Precaution . — The operation is directed to be conducted with care in a fume-chamber or in the open air, because the vapor of corrosive sublimate, which might possibly escape, is very acrid and highly poisonous. Its vulgar name is indicative of its properties. Ten grains of perchloride of mercury and the same quantity of chloride of ammonium in one pint of water, form the Liquor Hydrar- gyri Perchloridi, B. P. A dilute aqueous solution of perchloride of mercury is liable to decomposition, calomel being precipitated, water formed, and oxygen gas evolved. The presence of excess of chloride of ammonium, with a portion of which the mercuric chloride forms a stable double salt, prevents the decomposition. Seventh Synthetical Reaction, — Mix a few grains of the mercurous sulphate of the fifth reaction with about a third of its weight of chloride of sodium, and sublime in a test- tube ; crystalline mercurous chloride (HgCl) or calomel {Hydrargyri Subchloridum^ B. P., Hydrargyri Ghloridum 3Iite^ U. S. P.) results. Larger quantities may be pre- pared in the manner directed for corrosive sublimate, a somewhat higher temperature being employed ; similar precautions must also be observed. The proportions are 10 of mercuric sulphate to 7 of mercury and 5 of dry chlo- ride of sodium. ‘‘ Moisten the sulphate of mercury with some of the water, and rub it and the mercury together until globules are no longer visible ; add the chloride of sodium, and thoroughly mix the whole by continued tritu- 178 THE METALLIC RADICALS. ration. When dry sublime by a suitable apparatus into a chamber of such a size that the calomel, instead of adhering to its sides as a crystalline crust, shall fall as a fine (dull- white) powder on its floor. Wash this powder with boiling distilled water until the washings cease to be darkened by a drop of sulphydrate of ammonium. Finally, dry at a heat not exceeding 212®, and preserve in a jar or bottle impervious to light. Hg^SO, + 2NaCl = 2HgCl + IsXSO; Mercurous Chloride of Mercurous Sulphate of sulphate. sodium. chloride. sodium The term calomel [xaXo^, Jcalos, good, and melas, black) is said to relate to the use of the salt as a good remedy for Mack bile, but probably was simply indicative of the esteem in which black sul- phide of mercury was held, the compound to which the name calomel was first applied. Test for corrosive suMimate in calomel. — If the mercurous sul- phate contains mercuric sulphate, some mercuric chloride will also be formed.' Corrosive sublimate is soluble in water, calomel insolu- ble ; the presence of the former may therefore be proved by boiling a few grains of the calomel in distilled water, filtering and testing by sulphuretted hydrogen or sulphydrate of ammonium as described hereafter. If corrosive sublimate is present, the whole bulk of the colomel must be washed with hot distilled water till the filtrate ceases to give any indications of mercury. Corrosive sublimate is more soluble in alcohol, and still more in ether, calomel insoluble. Ether in which calomel has been digested should, therefore, after filtration, yield no residue on evaporation. Calomel is converted by hydrocyanic acid into mercuric salt, with separation of metallic mercury. Note. — The above process is that of the Pharmacopoeias ; but calomel may also be made by other methods. Calomel mixed with lard forms the Unguentum Hydrargyri Suhchloridi, B. P., and with sulphurated antimony, guaiacum resin, and castor oil, the Pilula Hydrargyri Suhchloridi Composita, B. P., Pilula Antimonii Comp>osita, U. S. P., or “ Plummer’s Pills.” The two Oxides. Eighth Synthetical Reaction . — Evaporate the mercuric- nitrate of the third reaction to dryness in a small dish, in a fume-chamber, or in the open air if more than a few grains have been prepared, and heat the residue till no more fumes are evolved; mercuric oxide (HgO), ‘‘Red Precipitate,” the Red Oxide of Mercury {Hydrargyri Oxi- dum Ruhrum,^ B. P. and U. S. P.), remains. 2(Hg2N03) = 2ITgO -f 4NO, -f O., Mercuric Mercuric Nitric Oxygen, nitrate. oxide. peroxide. MERCURY. 179 The nitric constituents of the salt may be partially economized by previously thoroughly mixing with the dry mercuric nitrate as much mercury as is used in its preparation, or as much as it already contains (ascertained by calculation from the atomic weights and the weight of nitrate under operation, as in making mercurous sulphate ^ p. 176), and well heating the mixture. In this case the free mercury is also converted into mercuric oxide. This is the official process, \ the Pharmacopoeial quantities being four ounces of mercury dissolved ; in four and a half fluidounces of nitric acid diluted with two ounces ' of water, the solution evaporated to dryness, the residue thoroughly mixed with four ounces of mercury, and the whole heated until acid vapors cease to be evolved. (Mercuric oxide is tested for nitrate by heating a little of the sample in a test-tube, when orange nitrous wapors are produced and are visible in the upper part of the tube, if nitrate is present). Hg 2 N 03 + Hg = 2HgO + 2 NO 2 Mercuric Mercury. Murcuric Nitric nitrate. oxide. peroxide. Mercuric oxide is an orange-red powder, more or less crystalline according to the extent to which it may have been stirred during preparation from the nitrate, much rubbing giving the crystals a pulverulent character. Mixed with yellow wax and oil of almonds it yields the Unguentum Hydrargyri Oxidi Ruhri, B. P. (1 part in 8). A similar ointment is official in U. S. P. Mercuric oxide, in contact with oxidizable organic matter, is liable to reduction to black or mercurous oxide. Ninth Synthetical Reaction. — To solution of corrosive sublimate in a test-tube or larger vessel add solution of potash or soda, or lime-water ; yellow oxide of mercury, Hydrargyri Oxidum Flavum^ U. S. P., or mercuric oxide (HgO), is precipitated. HgCl^ + Ca2HO = HgO + CaCl^ + H.,0 Mercuric Hydrate of Mercuric Chloi-ide of Water. cMoride. calcium. oxide. calcium. Eighteen grains of corrosive sublimate to ten ounces of lime-water form the Lotio Hydrargyri FLava, B. P. The precipitate only dif- fers physically from the red mercuric oxide ; the yellow is in a more minute state of division than the red. Mercuric oxide is very slightly soluble in water, but sufficiently so to communicate a decidedly metallic taste. Tenth Synthetical Reaction. — To calomel add solution of potash or soda, or lime-water ; black oxide of mercury, or mercurous oxide (Hg^O).is produced, and may’’ be filtered off, washed, and dried. (This reaction and the formation ; of a white curdy precipitate, on the addition of solution of nitrate of silver to the filtrate from the mercurous oxide, acidified by nitric acid, form sufficient evidence of 180 THE METALLIC RADICALS. a powder being or containing calomel. The curdy precipi- tate is chloride of silver.) Thirty grains of calomel to ten ounces of lime-water form the Lotto Hydrargyri Nigra, B. P. 2HgCl + Ca2HO = Hg,0 + CaCl, + H^O Mercurous Hydrate of Mercurous Chloride of Water, chloride. calcium. oxide. calcium. (5) Analytical Reactions ( Tests), (The mercury occurring as mercuric or mercurous saltj First Analytical Reaction , — The Copper Test, Depcrsi- tion of mercury upon, and sublimation from copper. — Plaice a small piece of bright copper, about half an inch long ' a quarter of an inch broad, in a solution of any sal^ mercury, mercurous or mercuric, and heat in a test-tube , the copper becomes coated with mercury in a fine state of division. (The absence of any notable quantity of nitric acid must be insured, or the copper itself will be dissolved. See below.) Pour away the supernatant liquid from the copper, wash the latter once or twice by pouring water into, and then out of, the tube, remove the metal, take off* exc"' of water by gentle pressure in a piece of filter-pape^ the copper by passing it quickly through a flame, hQ.V it by the fingers ; finally, place the copper in a dry test-tube, and heat to redness in a flame, the tube held in a horizontal position ; the mercury sublime.^ condenses as a white sublimate of minute globules on the cool part of the tube outside the flame. The globules ag- gregate on gently pressing with a glass rod, and are espe- cially visible where flattened between the rod and the side of the test-tube. Notes on the Test . — This is a valuable test, for several reasons : It is very delicate when performed with care. It brings before the observer the element itself — one which from its metallic lustre and fluidity cannot be mistaken for any other. It separates the element both from mercurous and mercuric salts. Mercury can in this way be readily eliminated in the presence of most other substances, or- ganic or inorganic. In performing the test the presence of any quantity of nitric acid may be avoided by adding an alkali until a slight permanent preci- pitate appears, and then reacidifying with a few drops of acetic or hydrochloric acid ; or by concentrating in an evaporating-dish after adding a little sulphuric acid. MERCURY. 181 Tests continued. (The mercury occurring as mercuric salt.) Second Analytical Reaction,— To a few drops of a solu- tion of a mercuric salt (corrosive sublimate, for example) add solution of iodide of potassium, drop by drop ; a preci- pitate of mercuric iodide (HglJ forms, and at first quickly redissolves, but is permanent when sufficient iodide of potassium has been added. Continue the addition of iodide of potassium ; the precipitate is once more redissolved. Note. — When first precipitated, mercuric iodide is yellowish-red, soon changes to a beautiful scarlet. Its solubility either in solu- tion of the mercuric salt or in solution of iodide of potassium renders the detection of a small quantity of a mercuric salt by iodide of r' tassium, or a small quantity of an iodide by a mercuric solution, icult, and hence lessens the value of the reaction as a test. , Third Analytical Reaction . — Add a solution of mercuric salt to solution of ammonia, taking care that the mixture, after well stirring, still smells of ammonia ; a white pre- cipitate falls. Ammoniated Mercury. Performed in a test-tube, this reaction is a very delicate test of presence of a mercuric salt ; performed in larger vessels, the uric salt being corrosive sublimate (3 ounces dissolved in 3 pints 4iHed water, the solution poured into 4 fluidounces of Solution mmonia, and the precipitate washed and dried over a water- it is the usual process for the preparation of ‘‘ white precipi- the old “ ammonio-chloride,” or “ amido-chloride of mercury,” now i^nown as Ammoniated Mercury [Hydrargyrum Ammoniatum^ B. P., and U. S. P.). Constitution of Ammoniated Mercury. — This precipitate is con- sidered to be the chloride of mercuric ammonium (NH2Hg"Cl) — that is, chloride of ammonium (NH^Cl) in which two atoms of univa- lent hydrogen are replaced by one bivalent atom of mercury. HgClj + 2NH,HO = NH2Hg"Cl + NH,C1 + 2H2O Mercuric Ammonia. “White Chloride of Water, chloride. precipitate.” ammonium. Varieties of Ammoniated Mercury. — If the order of mixing be reversed and ammonia be added to solution of mercuric chloride, a double chloride of mercuric-ammonium and mercury results (NH2HgCl, HgCl2) : it contains 76.55 per cent, of mercury. Pre- viously to the year 1826, “ white precipitate” was officially made by adding a fixed alkali to a solution of equal parts of corrosive subli- mate and sal-ammoniac; this gave a double chloride of mercuric- ammonium and ammonium (NH2Hg01,NH401), containing 65.57 per cent, of mercury. This compound is now knowm as wffiite precipitate,” because at a temperature somewhat below redness it fuses and then volatilizes. The white precipitate” which has been 16 182 THE METALLIC RADICALS. official since 1826 contains 79.52 per cent, of mercury. The true compound may be distinguished as “ inf usihle white precipitate,” from the fact that when heated it volatilises without fusing. An oint- ment of this body is official ( Uyiguentum Hydra%gyri Ammoniati, B. P. and U. S. P.). Prolonged w^ashing with w’ater converts “white precipitate” into a yellowish compound (NH 2 HgCl, HgO) ; hence the official preparation is seldom thoroughly freed from the chloride of ammonium wffiich is formed during its manufacture, and which, if present in larger proportion than seven or eight per cent., gives to it the character of partial or complete fusibility. Note. — Chloride of mercuric ammonium is only one member of a large class of similar compounds, derivable from the various salts of ammonium by displacement of atoms of hydrogen by other atoms. The composition of ammonio-nitrate of silver and ammonio-sulphate of copper, made without excess of ammonia (p. 153), is consistent with this vie^v. r HI n] H [ci l H ] Chlpvide of ammonium. N Hg" H H Cl Chloride of mercuric ammonium. r Ag 1 [no, I ^ I Nitrate of argent-arn rnon- ammonium. N, r cu" 1 I 1 I H ih; j Sulphate of cup r-a mm on- ammonium. SO, The composition of the crystals of ammonio-sulphate of copper (p. 169) is consistent with the second of the following formulae, the first being that of sulphate of ammonium : — N, r H,i ^ i so, I -*^2 I I H^ J N, Cu" 1 Am- ! 1- so. IH, J Fourth Analytical Reaction , — Pass sulphuretted hydro- gen through a mercuric solution ; a black precipitate of mercuric sulphide (HgS) falls. Note. — Sulphuretted hydrogen also precipitates mercurous sul- phide (Hg 2 S) from mercurous solutions ; and in appearance the pre- cipitates are alike ; hence this reagent does not distinguish between mercurous and mercuric salts. But in the course of systematic analysis, mercuric salts are thrown down from solution as sulphide after mercurous salts have been otherwise removed. The sulphides are insoluble in sulphydrate of ammonium. Note. — An insufficient amount of the gas gives a wffiite or colored precipitate of ox^^sulphide. Ftliiops Mineral, the Hydrargyri Sidphuretum cum Sulphur e, is a mixture of sulphide of mercury and sulphur, obtained on tritu- rating the elements in a mortar till globules are no longer visible. Its name is probably in allusion to its similarity in color to the skin of the Ethiop. It was formerly official. Vermilion is mercuric sulphide prepared by heating together sul- phur and mercury, and subliming the mixture [Hydrargyri Sidphu- return Ruhrnm, U. S. P.). MERCURY. 183 Tests continued. (The mercury occurring as mercurous salt.) Fifth Analytical Reaction. — To a solution of a mercurous salt (the mercurous nitrate obtained in the second syn- thetical reaction, for example) add hydrochloric acid, or any soluble chloride ; a white precipitate of calomel (HgCl) occurs. This reaction was formerly official in the Dublin Phar- macopoeia as a process for the preparation of calomel. Sixth Analytical Reaction. — To solution of a mercurous salt add iodide of potassium ; green mercurous iodide (Hgl) is precipitated. Seventh Analytical Reaction. — To a mercurous salt, dis- solved or undissolved (calomel), add ammonia; black salt (chloride) of mercurous ammonium (NH^Hg^Cl) is formed. Other tests for Mercury. The elimination of mercury in the actual state of metal by the copper test, coupled with the production or non- production of a white precipitate on the addition of hydro- chloric acid to the original solution, is usually sufficient evidence of the presence of mercury and its existence as a mercurous or mercuric salt. But other tests may some- times be applied with advantage. Thus, metallic mercury is deposited on placing a drop of the solution on a plate of gold (sovereign or half sovereign), and touching the drop and the edge of the plate simultaneously with a key; an electric current passes, under these circumstances, from the gold to the key, and thence through the liquid to the gold, decomposing the salt, the mercury of which forms a white metallic spot on the gold, while the other elements go to the iron. This is called the galvanic test.^ and is useful for clinical purposes. Solution of stannous chloride (SnCl 2 ) — see Index — from the readiness with which it forms stannic salts (SnCl^, Sn02, etc.), gives a white precipitate of mercu- rous chloride in mercuric solutions, and quickly still further reduces this mercurous chloride (and other mercury-salts) to a grayish mass of finely divided mercury ; this is the old magpie test., probably so called from the white and gray appearance of the precipitate. The reaction may even be obtained from such insoluble mercury compounds as “ white precipitate.’^ Confirmatory tests for mercuric and mer- curous salts will be found in. the action of solution of pot- 184 THE METALLIC RADICALS. ash, solution of soda, lime-water, solution of ammonia, and solution of iodide of potassium. {Vide pages 180 to 183.) Xormal alkaline carbonates produce 3 ^ellowish mercu- rous carbonate, and brownish-red mercuric carbonate, both of them unstable. Alkaline bicarbonates give mercurous carbonate and white (soon becoming red) mercuric oxysalt. Yellow chromate of potassium (K 2 CrOj gives, with mercurous salts, a red precipitate of mercurous chromate (Hg^CrO^). Mercuiy and all its compounds are volatile, subliming unchanged by heat: the experiment is most con- veniently performed in a test-tube. Antidote . — Albumen gives a white precipitate with solu- tion of mercuric salts ; hence the importance of administer- ing white of egg while waiting for a stomach-pump in case of poisoning b}^ corrosive sublimate. QUESTIONS AND EXEECJSES. 293. Name the chief ore of mercury, and describe a process for the extraction of the metal. 294. Give the properties of mercury. 295. In what state does mercury exist in ‘‘ Gray Powder ?” 296. What other preparations of metallic mercury itself are em- ployed in medicine ? 297. State the relation of the mercurous to the mercuric com- pounds. 298. Distinguish between an alloy and an amalgam. 299. State the formulae of the two Iodides of Mercury. 300. Under what circumstances does mercuric iodide assume tw'o different colors ? 301. Illustrate the chemical law of Multiple Proportions as ex- plained by the atomic theory, employing for that purpose the stated composition of the two iodides of mercury. 302. Write down the formulae of Mercurous and Mercuric Nitrates and Sulphates. 303. How is Mercuric Sulphate prepared 304. What is the formula of “ Turpeth MineraW^ 305. Describe the processes necessary for the convertion of mercury into Calomel and Corrosive Sublimate, using diagrams. 306. Why is black oxide of manganese sometimes mixed wdth the other ingredients in the preparation of corrosive sublimate ? 307. Give the chemical and physical points of difference betw^een calomel and corrosive sublimate. 308. How may a small quantity of calomel in corrosive sublimate be detected ? 309. Work out a sum showing how much mercury wdll be required in the manufacture of one ton of Calomel. Ans. 17 cw4. nearly. LEAD. 185 310. Mention official preparations of the chlorides of mercury. 311. Give the formulae and mode of formation of the Red, Yellow, and Black Oxides of Mercury, employing diagrams. 312. Explain the action of the chief general test for mercury. 313. How are mercurous and mercuric salts analytically distin- guished ? 314. Give a probable view of the constitution of Hydrargyrum Ammonzatum, and an equation showing how it is made. 315. What is the best temporary antidote in cases of poisoning by mercury ? LEAD. Symbol Pb. Atomic weight 207. Source . — The ores of lead are numerous ; but the one from which the metal is chiefly obtained is the sulphide of lead (PbS), or galena (from galene, tranquillity, perhaps from its supposed effect in allaying pain). Preparation. — The ore is first roasted in a current of air ; much sulphur is thus burnt off as sulphurous acid gas, while some of the metal is converted into oxide and a portion of the sulphide oxidized to sulphate. Oxidation being stopped when the mass presents cer- tain appearances, the temperature is raised, and the oxide and sul- phate, reacting on undecomposed sulphide, yield the metal and much sulphurous acid gas : — 2PbO + PbS = Pb3 + SO, PbSO, + PbS = Pb, + 2SO,. Uses. — The uses of lead are well known. Alloyed with arsenicum it forms common shot, with antimony gives type-metal, with tin sol- der, and in smaller quantities enters into the composition of Britan- nia metal, peiuter, and other alloys. The salts of lead used in pharmacy and all other preparations of lead are obtained, directly or indirectly, from the metal itself. Heated in a current of air, lead combines with oxygen and forms oxide of lead (PbO) {Plumhi Oxidum, B. P. and U. S. P.), a yellow powder [massicot), or, if fused and solidified, a brighter reddish-yellow heavy mass of brighiscalesAermed litharge (from lithos, a stone, and apyupo^, It is from this oxide that the chief lead compoundsaW^btained. Oxide of lead, by further roasting in a current of air, yields red lead (or minium), Pb^O^, or Pb 022 Pb 0 . Both oxides are much used by painters, paper-stainers, and glass- manufacturers. White lead is a mixture of carbonate (PbCOg) and hydrate of lead (Pb2HO) (commonly 2 molecules of the former to 1 of the latter), usually ground up with about 7 per cent, of linseed oil ; it is made by exposing lead, cast in spirals or little gratings, to the action of air, acetic fumes, and carbonic acid, the latter generated from decaying vegetable matter, such as spent tan ; oxy acetate of lead slowly -but continuously forms, and is as continuously decom- posed by the carbonic acid with production of hydrate and carbonate, 16 * 186 THE METALLIC RADICALS. or dry white lead. The grating-like masses, when ground, form the heavy white pulverulent off.cial Plumhi Carhonas, B. B. and U. S. P. The latter is the active constituent of JJnguentum Plumhi Car- bonatis, B. P. and U. S. P., the old Unguentum Cerussce. Lead compounds are poisonous, producing saturnine colic, or even paralysis. These effects are termed saturnine from an old name of lead, Saturn. The alchemists called lead Saturn, first, because they thought it the oldest of the seven then known metals, and it might therefore be compared to Saturn, who was supposed to be the father of the gods ; and, secondly, because its power of dissolving other metals recalled a peculiarity of Saturn, who was said to be in the habit of devouring his own children. Quantivalence. — The atom of lead is sometimes quadrivalent (Pb"") ; but in most of the compounds used in medicine it exerts bivalent activity only (Pb"). Reactions having {a) Synthetical and (h) Analytical Interest. (a) Synthetical Reactions. Acetate of Lead. First Synthetical Reaction. — Place a few grains of oxide of lead in a test-tube, add about an equal weight of water and two and a half times its weight of acetic acid, and boil ; the oxide dissolves and forms a solution of acetate of lead (Pb2C.^H302). When cold, or on evaporation (the solu- tion being kept faintly acid), crystals of acetate of lead (Pb2C2H302, 3H2O) are deposited. Larger quantities are obtained b}^ the same method. PbO -f 2HC2H3O2 = Pb 2 C 2 H 302 + H2O Oxide of lead. Acetic acid. Acetate of lead. Water. This is the official process for Plumhi Acetas, B. B. and U. S. P. The salt is vulgarly termed Sugar of Lead, from its sweet taste. Besides its direct use in Pharmacy, it forms three-fourths of the Pihda Plumhi cum Opio, B. P., is the chief constituent of Unguen- tum Plumhi Acetatis, B. P., and an ingredient in Suppositoria Plumhi Composita, B. P., and Suppositoria Plumhi and Supposi- toria Plumhi et Opii, U. S. P. Subacetate or Oxyacetate of Lead. Second Synthetical Reaction. — Boil acetate of lead with about four times its weight of water, and rather more than two-thirds its weight of oxide of lead ; the resulting filtered liquid is solution of oxyacetate of lead, Liquor Plumhi Suhacefafis, B. P, and U. S. P, LEAD. 18 t The official (B. P.) Liquor is made by boiling 5 ounces of ace- tate and 3^ of oxide in 1 pint of distilled water for half an hour (constantly stirring), filtering, and making up for any loss by evapo- ration by diluting the filtrate to 1 pint. A similar solution was used by M. Goulard, who called it Extrac- tum Saturni, and drew attention to it in 1770. It is now frequently termed Goulard’s Extract. A more dilute solution, 1 of Liquor and 1 of spirit in 80 of distilled water, is also official in the Pharma- copoeias, under the name of Liquor Plumbi Subacetatis Dilutus. The latter is commonly known as Goulard Water. The stronger solution is the chief ingredient in Unguentum Plumbi Subacetatis Compositum, B. P., a slight modification of the old Goulard's Cerate. Similar preparations are official in the United States Phar- macopoeia. Oxyacetates of Lead. — The official subacetate of lead is not a definite chemical salt. It is probably a mixture of two subacetates of lead, which are well-known crystalline compounds, and which the author is disposed to regard as having a constitution similar to that he has already indicated for some other salts (see Iron, Antimony, and Bismuth). Exposed to air it absorbs carbonic acid gas, and hydrato-carbonate of lead is deposited. Acetate of Lead (3 molecules) . . . Pbg 6 C 2 H 3 OJ B p f Pyro-oxyacetate of lead Pb 30402 H 302 ' \ Goulard’s oxyacetate of lead .... Pb 30 22 C 2 H 302 Oxide of lead (3 molecules) Pb 303 . PbO -h Pb2C2H302 = Pb202C2H302 Oxide of Acetate of Official “subacetate.” lead. lead. or 3PbO + 3 (Pb 2 C,H, 02 ) = Pb 3040 ,H 302 + Pb, 0 , 2 C 2 Hs 0 , Oxide of Acetate of Pyro-oxyacetate, Goulard’s oxyacetate. lead. lead. Tbe official “ subacetate.” Nitrate of Lead. Eed Lead. Peroxide of Lead. Third Synthetical Beaction, — Digest a few grains of red lead in nitric acid and water ; nitrate of lead (Pb2N O3) is formed, and remains in solution, while a puce colored per- oxide of lead (PbO^) is precipitated. Nitrate of Lead {Plumbi Nitras, B. P. and U. S. P.) is more directly made by dissolving litharge (PbO) in nitric acid; but the above reaction serves to bring before the reader two other oxides of lead, namely, red lead (Pb 304 ) and peroxide of lead (Pb 02 ). In the latter oxide the quadrivalent character of lead is obvious. Nitrate of lead is used officially in preparing iodide of lead ; for this purpose the above mixture is filtered, the precipitate of peroxide of lead purified from adhering nitrate by passing hot water through the filter, the filtrate and washings evaporated to dryness to remove excess of nitric acid, the residual nitrate of lead redissolved by ebul- lition with a small quantity of hot water, and the solution set aside to crystallize, or a portion at once used for the following experiment. Nitrate of lead forms white crystals derived from octahedra. 188 THE METALLIC RADICALS. Iodide of Lead. Fourth Synthetical Reaction. — To a neutral solution of nitrate of lead add solution of iodide of potassium ; a pre- cipitate of iodide of lead (Pblj) falls {Plumhi lodidum^ B. P. and U. S. P.). Equal weights of the salts may be used in making large quantities. Pb2N03 -f 2KI = Pbl, 4 - 2 KNO 3 Nitrate of Iodide of Iodide of^ Nitrate of lead. potassium. lead. potassium. Iodide of lead is the chief ingredient in Emplastrum Plumhi lodidi, B. P., and Unguentum Plumhi lodidi, B. P. and U. S. P. Crystals of Iodide of Lead. — Heat the iodide of lead with the supernatant liquid, and, if necessary, filter ; the salt is dissolved, and again separates in golden crystalline scales as the solution cools. Oleate of Lead (Lead Plaster). Fifth Synthetical Reaction. — >Boil together in a small dish some very finely-powdered oxide of lead, with about twice its weight of olive oil, and ten or twenty times as much water, well stirring the mixture, and from time to time replacing water that lias evaporated ; the product is a white mass of oleate of lead (Pb 2 Cj 3 H 3302 ) {Emplastrum Plumhi.^ B. P. and U. S. P.), glycerine remaining in solu- tion in the water. Larger quantities are prepared in the same manner. 3PbO + 3H,0 + 2(C3H,3C,,H330,) Oxide of Water. Oleate of glyceryl lead. (olive-oil or oleine). 2(C3H33H0) Hydrate of glyceryl (glycerine). The action between the oxide of lead and olive oil is slow, requir- ing several hours for its completion. The glycerine rudiy be obtained by treating the aqueous product of tlie above reaction with sulphuretted hydrogen to remove a trace of lead, then digesting with animal charcoal, filtering and evapo- rating. But on the large scale glycerine is now usually produced as a by-product in the manufacture Of candles ; for its elements are found in all vegetable and animal fats. ( Vide Index.) ^ 3(Pb2C.3H3,,03) Oleate of lead (lead plaster). Modes of forming chloride^ stdphide, chromate, sulphate, hy- drate, and other salts of lead are incidentally described in the follow- ing analytical paragraphs. LEAD. 189 (b) Reactions having Analytical Interest {Tests). First Analytical Reaction. — To a solution of lead salt (acetate, for example) add hydrochloric acid ; a white pre- cipitate of chloride of lead (PbCl^) is obtained. Boil the precipitate with much Tvater; it dissolves, but, on the so- lution cooling, is redeposited in small acicular crystals. Filter the cold solution, and pass sulphuretted hydrogen through it; a black precipitate (sulphide of lead, PbS) shows that the chloride of lead is soluble to a slight extent in cold water. Notei^A. white precipitate on the addition of hydrochloric acid, soluble 1*0 hot water, and blackened by sulphuretted hydrogen, suffi- ciently distinguishes lead salts from those of other metals, but the non-production of such a precipitate does not prove the absence of a small quantity of l^d, chloride of lead being slightly soluble in cold water. Hydrochloric acid will be found to be a useful but not a delicate test for lead. Second Analytical Reaction. — Through a dilute solution of a lead salt joass sulphuretted hydrogen ; a black pre- cipitate of sulphide of lead (PbS) occurs. Lead in Water , — The foregoing is a very delicate test. Should a trace of lead be present in water used for drinking-purposes, sulphu- retted hydrogen will detect it. On passing the gas through a pint of such water, a brownish tint, more or less deep, is produced. If the tint is scarcely perceptible, set the liquid aside for a day ; the gas will become decomposed and a thin layer of sulphur be found at the bottom of the vessel, white if no lead be present, but more or less brown if it contain sulphide of lead. Third Analytical Reaction. — To solution of a lead salt add sulphydrate of ammonium ; a black precipitate of sul- phide of lead falls, insoluble in excess. Fourth Analytical Reaction. — To solution of a lead salt add solution of chromate of potassium (K^CrOJ ; a yellow precipitate of chromate of lead (PbCrO^) is formed, inso- luble in weak acids. Chromes . — This reaction has technical as well as analytical in- terest. The precipitate is the common pigment termed chrome yel- low, or lemon chrome. Boiled with lime and water, a portion of the chromic radical is removed as soluble chromate of calcium, and an oxychromate of lead, of a bright red or orange color [orange chrome), is produced. Fifth Analytical Reaction. — To solution of a lead salt add dilute sulphuric ac.id, or solution of a sulphate ; a white precipitate of sulphate of lead (PbSOJ falls. 190 THE METALLIC RADICALS. Sulphate of lead is slightly soluble in strong acids, and in solu- tions of alkaline salts ; it is insoluble in acetic acid. In dilute solutions this sulphuric reaction does not take place im- mediately ; the precipitate, however, falls after a time ; its appear- ance may be hastened by evaporating the solution nearly to dryness and then rediluting. The white precipitate always noticed in the vessels in which diluted sulphuric acid is kept, is sulphate of lead, derived from the leaden chambers in which the acid is made ; solubility in strong acid and insolubility in weak, explains its appearance. Antidotes . — From the insolubility of sulphate of lead in water, the best antidote in a case of poisoning by the acetate or other soluble salt of lead, is a soluble sulphate, such as Epsom salt, sulphate of sodium or alum, vomiting being also induced, or the stomach-pump applied as quickly as possible. Other tests for lead will be found in the reaction with iodide of potassium (vide p. 188) ; with alkaline carbonates.^ a white precipitate ( 2 PbC 03 -t-Pb 2 H 0 ) insoluble in excess ; with alkalies.^ a white precipitate (Pb2HO) more or less soluble in excess ; with alkaline phosphates.^ arseniates., ferrocyanides and cyanides., precipitates mostly insoluble, but of no special analytical interest. Insoluble salts of lead are decomposed by solutions of potash (KHO) or soda (NaHO). The metal is precipitated in a beautifully crystalline state by metallic zinc and some other metals ; the lead tree is thus formed. The blowpipe-flame decomposes solid lead compounds placed in a small cavity in a piece of charcoal, a soft malleable bead of metal being produced, and a yel- lowish ring of oxide deposited on the charcoal. QUESTIONS AND EXEPCISES. 316. Write down equations descriptive of the smelting of galena. 317. Mention some of the alloys of lead. 318. How is litharge produced ? 319. Give the formulm of white lead and red lead. 320. Describe the manufacture of white lead. 321. What is the quantivalence of lead ? 322. Draw a diagram expressive of the formation of Acetate of Lead. 323. Describe the preparation and composition of Liquor Plumbi Subacetatis. 324. What is the action of nitric acid on red lead, litharge, and metallic lead ? 325. How is the official Iodide of Lead prepared? SILVER. 191 326. Describe the reaction between oxide of lead, water, and olive 'oil, at the temperature of boiling water, and give chemical formulae explanatory of the constitution of the products. 327. Mention the chief tests for lead. 328. How would you search for lead in potable water ? 329. What is the composition of chrome yellow ? 330. State a method whereby lead, barium, and silver may be separated. 331. Name the best antidote in case of poisoning by salts of lead. SILVEK. Symbol Ag. Atomic weight 108. Source . — This element occurs in nature in the free slate and as ore, the common variety being sulphide of silver (Ag.^S) in combina- tion with much sulphide of lead, forming argentiferous galena. Preigaration . — The lead from galena (p. 185) is melted and slowly cooled ; crystals of lead separate and are raked out from the still fluid mass, and thus an alloy very rich in silver is finally obtained : this is roasted in a current of air, whereby the lead is oxidized and removed as litharge, pure silver remaining. Other ores undergo various preparatory treatments according to their nature, and are then shaken with mercury, which amalgamates with and dissolves the particles of silver, the mercury being subsequently removed from the amalgam by distillation. Soils and minerals containing metallic silver are also treated in this way. An important improvement in the amalgamation process, by which the mercury more readily unites with the silver, consists in the addition of a small proportion of sodium to the mercury — a recent discovery simultaneously made in England by Crookes, and in New York by Wurtz. Reactions having { a ) Synthetical and ih ) Analytical Interest. (a) Synthetical Reactions, Impure Nitrate of Silver. First Synthetical Reaction , — Dissolve a silver coin in nitric acid; nitric oxide gas (NO) and nitrous anhydride (N2O3) are evolved, and a solution of nitrates of silver and copper obtained. Silver Coinage . — Pure silver is too soft for use as coin, it is there- fore hardened by alloying with copper. The silver money of England contains 7.5, of France 10, and of Prussia 25 per cent, of copper. One pound troy of standard silver is coined into 66 shillings, of which the metal is worth from 60s. to 62s. according to the market price of silver. The standard fineness of silver is 0.925, three alloy in 40. 192 THE METALLIC RADICALS. The fineness of the French standard silver is 0.900 in the five-franc piece ; but an inferior alloy of 0.835 is used for the lower denomina- tions. The single-franc piece, composed of the latter alloy, is still made to weigh five grammes, the weight originally chosen for the franc as the unit of the monetary scale when the fineness of the coin was 0.900. It has now become a token, like the British shilling, of which the nominal value exceeds the metallic value. British silver coins are a legal tender in payments to the amount of 40s. only. Chloride of Silver. Second Synthetical Reaction — To the product of the above reaction add water and h^-drochloric acid or a solu- ble chloride ; white chloride of silver (AgCl) is precipitated, copper still remaining in solution. Collect the precipitate on a filter, and wash with water ; it is pure chloride of silver. Note . — The nitrates of silver and copper may also be separated by evaporating the solution of the metals in nitric acid to dryness, and gently heating the residue, when the nitrate of copper is decomposed, but the nitrate of silver unaffected. The latter may be dissolved from the residual oxide of copper by water. Chloride of silver may be obtained in crystals by evaporation of its solution in ammonia. Pure Silver. Third Synthetical Reaction, — Place the chloride of silver of the previous reaction in a dish, wet it with dilute sul- phuric acid, and float a piece of sheet zinc on the mixture; metallic silver is precipitated, and after about one day wholly removed from solution. Collect the precipitate on a filter and wash with water ; it is pure metallic silver, and is readily fusible into a single button. Note . — Chloride of silver may also be reduced to a lump of the metal by fusion, in a crucible, with about half its weight of carbonate of sodium. Pure Nitrate of Silver, Fourth Synthetical Reaction. — Dissolve the pure silver of the previous reaction in nitric acid (3 of silver require about 2 or 2^ of strong acid diluted wdth 5 of water), and remove excess of acid by evaporating the solution to dry- ness, slightly heating the residue; the product is pure nitrate of silver. Dissolve by heating with a small quan- tity of water; on the solution cooling, or on evaporation, colorless tabular crystals of nitrate of silver are obtained. ^ c SILVER. 193 SAg, + 8 HNO 3 = 2N0 + 6 AgN 03 + 4H,0 Silver. Nitric acid. Nitric Nitrate of Water. oxide. silver. Notes. — The solution of pure or refined silver [Argentum Purifi- caiitm, B. P., Argentum U. S. P.) in nitric acid, evaporation, and crystallization constitute the official process for the preparation of the nitrate [Argenti Nttras, B. P. and U. S. P.). The salt fused, and poured into proper moulds, yields the white cylindrical sticks or rods [Argenti Nitras Fusa, U. S. P.) commonly termed caustic (from »:aJco, kaio, I burn), or lunar caustic. (The alchemists called silver Diana or Luna, from its supposed mysterious connection with the moon.) The specimen of nitrate of silver obtained in the above reaction, dissolved in water, will be found useful as an analytical reagent. Nitrate of silver is soluble in rectified spirit; but after a time reaction and decomposition occur. Silver salts are decomposed when in contact with organic matter, especially in the presence of light or heat, the metal itself being lib- erated, or a black insoluble compound formed. Hence the value of the nitrate in the manufacture of indelible ink for marking linen ; hence, too, the reason of the practice of rendering silver solutions clear by subsidence and decantation, rather than by filtration through paper ; and hence the cause of those cases of actual combustion which have been known to occur in preparing pills containing oxide of silver and essential oil or other organic matter. Oxide of Silver. Fifth Synthetical Reaction, — To a few drops of solution of nitrate of silver add solution of potash or soda or lime- water; an olive-brown precipitate of oxide of silver (A g., 0 ) occurs. The washed and dry oxide, like most silver com- pounds, is decomposed by heat with production of metal. The Argenti Oxidum, B. P. and U. S. P., is thus made, lime- water (solution of potash U. S. P.) being the precipitant employed, soda and potash not being so readily removed by washing. Three and a half pints of lime-water will decompose half an ounce of nitrate of silver. 2 AgN 03 + Ca2HO = Ag^O + Ca 2 N 03 + H,0 Nitrate of Hydrate of Oxide of Nitrate of Water, silver. calcium. silver. calcium. Methods of forming several other salts of silver are incidentally mentioned in the following analytical paragraphs. (h) Reactions having Analytical Interest, ( Tests,) First Analytical Reaction — To a solution of a silver salt add hydrochloric acid or other soluble chloride ; a white curdy precipitate of chloride of silver falls. Add nitric acid, and boil ; the precipitate does not dissolve. Pour off n 194 THE >i*ETALLIC RADICALS. the acid and add solution of ammonia; the precipitate dis- solves. Neutralize the ammoniacal solution by an acid; the chloride of silver is re-precipitated. This is the most characteristic test for silver. The precipitated chloride is also soluble in solutions of hyposulphite of sodium or cy- anide of potassium — facts of considerable importance in photo- graphic operations. Other analytical reagents than the above are occasionally useful. ^Sulphuretted hydrogen, or sulphydrate of am- monium, gives a black precipitate, sulphide of silver ( Ag.^S), insoluble in alkalies. Solutions of potash or soda give a brown precipitate, oxide of silver (Ag.^0), converted into a fulminating compound by prolonged contact with am- monia. Phosphate of sodium gives a jiale yellow pre- cipitate, phosphate of silver (Ag.jPOj, soluble in nitric acid and in ammonia. ^Arseniate of ammonium gives a chocolate-colored precipitate, arseniate of silver (AggAsOj, already noticed in connection with arsenic acid. ^Iodide or bromide of potassium gives a yellowish-white precipitate, iodide or bromide of silver (Agl or AgBr), insoluble in acids and only slightly soluble in ammonia. -Cy^anide of potassium gives a white precipitate, cyanide of silver (AgCy), soluble in excess, sparingly soluble in ammonia, insoluble in dilute nitric acid, soluble in boiling concen- trated nitric acid. Ar genii cyanidum^ U. S. P., is made by distilling a mixture of ferrocyanide of potassium and di- luted sulphuric acid, and passing the resijjting hy^drocy’anic acid into a solution of nitrate of silver : HCy -f AgNOj = AgCy -f HNO 3 (the precipitate is well washed and dried). Yellow chromate of potassium (K 2 CrO^) gives a red precipitate, chromate of silver (Ag.^CrOJ. Red chro- mate of potassium also gives a red precipitate, acid chro- mate of silver (Ag 2 Cr 04 ,Cr 03 ). Many organic acids afford insoluble salts of silver. Several metals displace silver from solution, mercury forming in this way a ciys- talline compound known as the silver tree, or Arbor Dianee. — ^In the blowpipe flame, silver salts, placed on charcoal with a little carbonate of sodium, yield bright globules of metal accompanied by no incrustation as in the corres- ponding reaction with lead salts ; the experiment may be performed with the nitrate, which first melts and then, like all nitrates, deflagrates, yielding a white metallic coating of silver which slowly^ aggregates to a button. COPPER, MERCURY, LEAD, SILVER. 195 Antidotes . — Solution of common salt, sal-ammoniac, or any other inert chloride should obviously be administered where large doses of nitrate of silver have been swallowed. A quantity of sea-water or brine would convert the silver into insoluble chloride, and at the same time produce vomiting. QUESTIONS AND EXERCISES. 332. By what process is silver obtained from argentiferous galena ? 333. What weight of English silver coin will yield one pound of pure nitrate of silver ? 334. How may the metal be recovered from an impure mixture of silver salts ? 335. Give a diagram showing the formation of nitrate of silver from the metal. 336. Describe the reaction of lime water and nitrate of silver. 337. Mention the chief test for silver, and the precautions to be observed in order that silver salts may be distinguished from those of lead and mercury. 338. Name the antidote for silver. DIRECTIONS FOR APPLYING SOME OF THE FOREGOING REACTIONS TO THE ANALYSIS OF AN AQUEOUS SOLUTION OF SALTS OF OJSTE OF THE METALS, CoPPER, MeRCURY (EITHER AS MERCUROUS OR MERCURIC SALT), LeAD, SiLVER. Add hydrochloric acid : — Silver is indicated by a white curdy precipitate, solu- ble in ammonia. Mercurous salts also by a white precipitate, turned black by ammonia. Lead by a white precipitate, insoluble in ammonia. Confirm by boiling another portion of the hydro- chloric precipitate in water ; it dissolves. If hydrochloric acid gives no precipitate, silver and mer- curous salts are absent. Lead can only be present in very small quantity. Mercuric salts may be present. Copper may be present. Divide the liquid into three portions, and apply a direct test for each metal. Lead is best detected bj^ the sulphuric test ; the tube being set aside for a time if the precipitate does not appear at once. Mercury is best detected by the copper test. If present, it occurs as mercuric salt. 196 THE METALLIC RADICALS. Copper betrays itsel^^y the blue color of the liquid under exanpuation. Confirm by the ammonia test. ^ If the above reactions are not thoroughly conclusive, confirmatory evidence should be obtained by the applica- tion of some of the other reagents for copper, mercury, lead or silver. Table of short directions for applying ^IfE^op the ^ FOREGOING REACTIONS TO THE ANALYSIS OF AN SSl^EOUS ^ SOLUTION OF SALTS OF ANY OR ALL OF THE METALS COP- PER, Mercury (either merqurous^r mercuric salt, OR both). Lead, Silver. Add hydrochloric acid, filter, and wash the precipitate with a small quantity of cold water. Ppt. Pb Hg(ous) Ag^ Wash with boiling water. - ^ ^ Filtrate Cu Hg(ic) Pb. Divide into three portions. Test for Ppt. Hg(ous) Ag Add Am HO. Filtrate Pb. Add H,SO„ white ppt.* Cu by AmHO; blue sol. Hg (mercuric) by Cu; globules. Pb by H2S0^; white ppt* Precipitate Hg (mercurous) black. Filtrate Ag. Add HNO3, white ppt. * Liquids containing only a small quantity of lead do not readily yield sulphate of lead on the addition of sulphuric acid. Before lead can be said to be absent, therefore, the liquid should be evaporated to dryness with one drop of sulphuric acid, and the residue digested in water; any sulphate of lead then remains as a heavy white in- soluble powder. ELEMENTS HITHERTO CONSIDERED. CHART FOR ONE COMMON MET 19T Hi CQ Pi s P3 O M ^ ra bD p biO 6 w ' bD^ P .o %ai e bS ^ be ^ cB a bjoxj S US bcx> ':S ^ S.22 ‘p. ® p be . 4^ P^ G ^ Q^.S fl .P rrt • <3^ > . %-> Xi i ns PJ P-S ii o o t-'g P p,-- feSH 2 ^ -e 3 o § o g •" a fee i -g to r\ S-i hrl c3 ^ cs Ph ce W in excess. Zn, white ppt. soluble in excess. 198 THE METALLIC RADICALS. The group-tests of this Table 4^’® HCl, HjS, NH4HS, and (NH4)2C03. COMMON METALLIC RADICALS. 199 OUTLINE OF THE PRECEDING TABLES. II Cl H^S Am IIS Am.^CO.^ Am.^HAsO^ Hg Cu ' d Zn Ba Mg K (as mercurous Hg (as mer- salt) Pb ® 05 ' ^ s A1 Ca Na curic salt) Ag Pb ^ d Fe Am As d aj 05 Sb ' d a c < 05 The practical student should examine solutions containing the above metals until he is able to analyze with facility and accuracy. In this way he will best perceive the peculiarities of each element and their general relations to each other. As the rarer metals are not included here, the tables are not complete analytical schemes ; further remarks concerning them, therefore, are for the present deferred. QUESTIONS AND EXERCISES. 339. Give processes for the qualitative analysis of liquids contain- ing the following substances : — a. Antimony and Mercurous salt. h. Lead and Calcium. c. Silver and Mercurous salt. cl. Lead and Mercuric salt, e. Copper and Arsenicum. /. Arsenicum and Antimony. g. Aluminium and Zinc. li. Iron and Copper. i. Magnesium, Calcium, and Potassium. j. Silver, Antimony, Zinc, Barium, and Ammonium. 340. Enumerate the so-called group-tests. 341. Give a general sketch of the method of analyzing a solution suspected to contain two or more salts of common metals. 342. Classify the common metals according to their analytical relations. 200 RARER METALLIC RADICALS. METALS OF MINOR PHARMACEUTICAL IMPORTANCE. Thus far has been considered, somewhat in detail, the chemistry of the common metals, salts of which are frequently used in medicine or in testing medicinal substances. These are : — Potassium, Barium, Zinc, Arsenicum, Mercury, Sodium, Calcium, Aluminium, Antimony, Lead, Ammonium (?), Magnesium, Iron, Copper, Silver. There still remain eleven metals, eight of wLich are mentioned in the British Pharmacopoeia, namely : — Lithium, Chromium, Gold, Cadmium, Manganese, Tin, Platinum, Bismuth. Compounds of the remaining three are sufficiently common to occa- sionally come under notice : — Strontium, Cobalt, Nickel. These eleven metals of minor pharmaceutical interest may be shortly studied, a few only of the reactions of each (just those men- tioned in the following pages) being performed. When all have been thus treated, their respective positions in the analytical groups will be indicated and a tabular scheme by wffiich an analysis of a solution containing any metal may be effected. Thus, step by step, we may learn how to analyze almost any substance that may occur, and know to what extent the presence of a rarer wdll interfere with the ordinary tests for a common element : additional illustrations of the working of chemical laws will be acquired, and the store of chemical and pharmaceutical facts increased. The opportunity thus afforded for improvement in habits of neatness in manipulation, pre- cision, and classification is another and no mean reason why such experiments should be prosecuted, the direct value of which may not be considerable to medical and pharmaceutical learners. LITHIUM. Symbol L. Atomic weight 7. Lithium is widely distributed in nature, but usually in minute pro- portions compared with other elements. A trace of it may be found in most soils and waters, a Cornish spring containing even consider- able quantities as chloride. One salt used in medicine is the Citrate (L^Cgll 507 ) [Lithii Citras, U. S. P.), occurring in white deliquesent crystals or powder, prepared by dissolving 50 grains of the Carbonate (L^CO^) and 100 of citric acid in 1 ounce of water, evaporating to a low bulk, and LITHIUM. 201 setting aside in a dry place to crystallize, or at once evaporating to dryness and powdering the residue. 3L,C03 + = 2L3C,H,0, + m,0 + 3CO., Carbonate Citric acid. Citrate of Water. Carbonic of lithium. lithium. acid gas. The carbonate {Litliii Carhonas, U. S. P.) is a white granular powder obtained from the minerals which contain lithium ; namely, lepidolite (from lepis, a scale, and uOo^, Uthos, a stone ; it has a scaly appearance), triphane (from treis, three, and pliaind, I shine), or spodumene (from cyrtoSdw, spodod, to reduce to ashes, in allusion to its exfoliation in the blowpipe-flame), and peta- lite (from rd'ta’Kov, petalon, a leaf ; its character is leafy and lami- nated). Each contains silicate of aluminium, with fluoride of potas- sium and lithium in the case of lepidolite, and silicate of sodium and lithium in the others. Liquor Litliioe Effervescens, B. P., is a solu- tion of 10 grains of carbonate of lithium in 1 pint of water charged with 7 times its volume of carbonic acid gas and kept in ordinary aerated water-bottles. Half a pint, evaporated to dryness, yields 5 grains of a white solid residue, answering to the tests for carbonate of lithium Ten grains of the latter salt neutralized with sul- phuric acid, and afterwards heated to redness, leave 14.86 grains of dry sulphate of lithium, which, when redissolved in distilled water, yields no precipitate with oxalate of ammonium or solution of lime,” indicating absence of salts of calcium and aluminium. Citrate of lithium should yield by incineration 52.8 per cent, of white carbo- nate of lithium. Urate of Lithium^ is more soluble than urate of sodium ; hence lithium preparations are administered to gouty patients in the hope that urate of sodium, with which such systems are loaded, may be converted into urate of lithium and removed. In chemical position lithium stands between the alkaline and the alkaline-earth metals, its hydrate, carbonate, and phosphate being slightly soluble in water. The double chloride of platinum and lithium also is soluble in water. Its atom is univalent, L'. Analytical Reaction , — Moisten the end of a platinum wire with solution of a minute particle of solid lithium salt, and introduce it into the flame of a Bunsen burner or other slightly colored flame (spirit-lamp or blowpipe-flame) ; a magnificent crimson tinge is imparted. The light emitted by ignited lithium vapor is of a purer scarlet than that given by strontium, the next element. When the flames are examined by spectral analysis (physically analyzed by a prism), the red rays are, in the case of strontium, found to be associated with blue and yellow, neither of which is present in the lithium light. * Urates will be considered subsequently in connection with uric acid. 202 RARER METALLIC RADICALS. STRONTIUM. Symbol Sr. Atomic weight 87.5. ^£ource . — Strontium is not widely distributed in nature ; but the ^bonate (SrCOg), known as strontzamte, and the sulphate (SrSO^) known as celestme (from coelum, the sky, in allusion to its occasional bluish color), are by no means rare minerals. Salts of strontium are not employed in medicine. They are chiefly used by firework manufacturers in preparing red fire. The color they impart to flame is a beautiful crimson — ignited strontium vapor emitting red rays, as already explained. Nitrate of strontium (Sr 2 N 03 ) is best for pyrotechnic compositions, its oxygen enabling it to burn freely when mixed with charcoal, sulphur, etc. It, or any salts, may be obtained by dissolving the carbonate in the appropriate acid, or by igniting the cheaper sulphate with coal, whereby sulphide (SrS) is produced, and dissolving this in acid. The position of strontium among the chemical elements is between barium and calcium ; its sulphate is very sparingly soluble in water. Its atom, like those of barium and calcium, is bivalent (Sr"). Analytical Reactions (Tests). Firist Analytical Reaction^ — To a solution of a strontium salt (Sr 2 N 03 or SrCl^) add carbonate of ammonium ; a white precipitate of carbonate of strontium (SrCOJ falls. Second Analytical Reaction. — To a solution of a stron- tium salt add sulphuric acid previously so diluted that it will not precipitate calcium salts or an equally dilute solu- tion of any other sulphate ; a wdiite precipitate of sulphate of strontium (SrSO^) falls. The formation of this pre- cipitate is promoted by stirring and by" setting the liquid aside for some time. Barium is precipitated immediately under similar circumstances. Third Analytical Reaction. — To a dilute solution of a strontium salt add yellow chromate of potassium ; no pre- cipitate falls. Barium may be separated from strontium by chromate of potas- sium, that reagent at once precipitating barium from aqueous or acetic solutions. Fourth Analytical Reaction. — Insert a fragment of a strontium salt in the blowpipe-flame, or other equally colorless flame, or hold the end of a platinum wire dipped into a strontium solution in the flame ; a crimson color is imparted. Other Analytical Reactions. — Alkaline phosphates, arse- niates, and oxalates give white insoluble precipitates with MANGANESE. 203 strontium as with barium and calcium.- — —Strontium, like calcium, but unlike barium, is not precipitated by hydro- fluosilicic acid. Cerium. Ce. At. wt. 22. — This element occurs in the mineral cerite (a silicate of iron, calcium, and the three rare metals, cerium, lanthanium, and didymium) ; also occasionally as impure fluoride, carbonate, and phosphate. The oxalate of cerium, a white granular powder, is the only official salt ; it may be obtained from cerite by boiling the powdered mineral in strong hydrochloric acid for several hours, evaporating, diluting, and filtering to separate silica ; adding ammonia to precipitate hydrates of all the metals except calcium ; filtering off, washing, redissolving in hydrochloric acid, and adding oxalic acid to precipitate oxalate of cerium. The preparation will still contain oxalates of lanthanium and didymium ; it is therefore strongly calcined, the resulting oxides of lanthanium and didymium dissolved out by boiling with a concentrated solution of chloride of ammonium, the residual oxide of cerium dissolved in hydrochloric acid, and oxalate of ammonium added to precipitate pure oxalate of cerium (Ce"C.^ 04 , 3H.^O). Oxalate of cerium ( Gerii Oxalas, B. P. and U. S. P.) is decom- posed at a dull red heat, a salmon-colored mixture of oxides remain- ing ; usually a little didymium is present, giving the ignited residue a reddish-brown color ; it is then soluble in boiling hydrochloric acid (without effervescence; indicating, indirectly, absence of earthy and other carbonates or oxalates), and the solution gives, with excess of a saturated solution of sulphate of potassium, a crystalline precipitate of double sulphate of cerium and potassium. Alumina mixed with oxalate of cerium may be detected by boiling with solution of potash, filtering, and adding excess of solution of chloride of ammonium, when a white flocculent precipitate of hydrate of aluminium will be obtained. The oxalic radical is recognized by neutralizing the pot- ash solution by acetic acid and adding chloride of calcium ; white oxalate of calcium is then precipitated ; this precipitate, though in- soluble in acetic, should be wholly dissolved by hydrochloric acid. MANGANESE. Symbol Mn. Atomic weight 55. Source. — Manganese is a constituent of many minerals, and as black oxide (MnO.J (Manganesii Oxidum Nigrum, B. P. and U. S. P.), or pyrolusite (from Ttup, pur, fire, and lusts, a loosing or resolving, in allusion to the readiness with which it is split up by heat into a lower oxide and oxygen), occurs frequently in abundance in the southwest of England, Aberdeenshire, and most of the coun- tries of Europe. It is met wdth as a steel-gray mass of prismatic crystals, or in black shapeless lumps. The chemical position of manganese is close to iron and three other metals still to be considered — cobalt, nickel, and chromium. Its atom apparently has sexivalent affinities, as seen in manganate of potassium (K 2 Mn 04 ) ; but commonly it is quadrivalent (Mn^^) or bivalent (M"). 204 RARER METALLIC RAIUCALS. Uses . — Metallic manganese is only used in alloy with iron in the manufacture of some varieties of steel. The black oxide is an im- portant agent in the production of chlorine, the preparation of green and red disinfecting manganates, purple glass, and black glazes for earthenware. Reactions having either Synthetical or Analytical Interest., or both. First Reaction, — Boil a few grains of black oxide of manganese with so£pe drops of hydrochloric acid until chlorine ceases to be evolved ; add water, and filter ; the filtrate is a solution of manganous chloride (MnClJ. MnO, + 4HC1 = MnCl, + 2H,0 + Cl,. This is the reaction commonly applied in the preparation of chlo- rine gas. It is also a ready method of preparing a manganous salt for analytical experiments. Coupled with the application of reagents to the filtrate, the reaction is that by which a black powder or mine- ral would be recognized as black oxide of manganese. Black oxide of manganese dissolves in cold hydrochloric acid, forming a dark- brown solution of a higher chloride or chlorides, MnClg, Mn^Cl^, or, possibly, MnCl^. Second Reaction, — Heat a particle of a manganese com- pound with a grain or two of carbonate and hydrate of potassium and a fragment of nitrate or chlorate of potas- sium on platinum foil in the blowpipe-flame; a green mass containing many an ate of potassium (K^MnOj results. Boil the foil in a little water ; the green manganate dis- solves and soon changes to solution of the purple perman- ganate of potassium (K^Mn,Oy). This is a delicate analytical test for manganese. The reaction is similar to that by which permanganate of potas- sium [Potassii Permanganas, U. 8. P.) is directed to be prepared for use in volumetric analysis. Liquor Potassii Permanganatisy U. 8. P., is a solution of 80 grains of permanganate of potassium in 1 pint of distilled water. Equations showing the exact action which occurs in making the salt according to the process of the British Pharmacopoeia have already been given in connection with the com- pounds of potassium (vide p. 64). The proportions of ingredients and details of the operation are as follows : — lleduce 3^ parts (for experiment each “ part” may be ^th oz.) of chlorate of potassium to fine powder, and mix it with 4 of black oxide of manganese ; put the mixture into a porcelain basin, and ( add to it 5 parts of solid caustic potash, previously dissolved in 4 | parts of water. Evaporate to dryness, stirring diligently to prevent spirting. Pulverize the mass, put it into a covered Hessian or Cornish crucible, and expose it to a dull red heat (not higher) for an MANGANESE. 205 hour (20 or 30 minutes for quantities of 1 or 2 ozs.), or till it has assumed the condition of a semifused mass. Allow to cool, pulverize, and boil with about 30 parts of water. Let the insoluble matter subside, decant the fluid, boil again with about 10 parts of water, again decant, neutralize the united liquors accurately with diluted sulphuric acid (or, better, carbonic acid gas), and evaporate till a pellicle forms. Set aside to cool and crystallize. Drain the crystal- line mass, boil it in 6 parts of water, and strain through a funnel the throat of which is lightly obstructed by a little asbestos or gun-cot- ton. Let the fluid cool and crystallize, drain the dark purple slen- der prismatic crystals, and dry them by placing under a bell jar over a vessel containing sulphuric acid. Instead of converting the manganate into permanganate by ebul- lition, by which one-third of the manganate is lost, Stadelar recom- mends chlorine to be passed through the cold solution until the green color is entirely changed to purple. Solutions of the manganates of potassium and sodium are in com- mon use as disinfectants under the name of Condy’s fluid. They act by oxidizing organic matter, the manganic or permanganic radical being reduced to black manganic oxide, or even a lower oxide. The reason for using asbestos instead of paper in filtering the solutions will now be understood. The changes in color which the green mass of the above process undergoes when dropped into warm water procured for it the old name of mineral chameleon. Third Reaction . — Make a borax bead by" heating a frag- ment of the salt on the looped end of a platinum wire in the blowpipe-fllame until a clear transparent globule is ob- tained. Place on the bead a minute portion of a manga- nese compound, or touch it with a drop of solution. Again fuse the borax ; a bead of a violet or amethystine tint is produced. This is a good analytical reaction. It has also synthetical interest, illustrating the use of black oxide of manganese in producing common purple-tinted glass. Expose the bead to the reducing part of the flame, the part nearer to the blowpipe, where there are highly heated hydro-carbon gases greedy of oxygen ; the color disappears. This is owing to the reduction of the manganic compound to a manganous condition, in which it no longer possesses peculiar color- ing-power. This action also illustrates the use of black oxide of manganese in glass-manufacture. Glass when first made is usually of a green tint, owing to the presence of ferrous impurities; the addition of manganic oxide to the materials converts the ferrous into ferric compounds, which have comparatively little colorific power, it itself being thereby reduced to manganous oxide, which also gives but little color. If excess of manganic oxide be added, a purple tint is produced. 18 20 G RARER M E T A L I. I C RADICALS. Fourth Reaction , — Through a solution of a manganous salt acidified by hydrochloric acid pass sulphuretted hydro- gen ; no decomposition occurs. Add ammonia; the sul- phydrate of ammonium thus formed causes the precipitation ^f a yellowish-pink or flesh-tinted precipitate of manganous sulphide (MnS) in a hydrous state. This reaction is characteristic, sulphide of manganese being the only flesh-colored sulphide known. The salt used may be the manga- nous chloride obtained in the first reaction ; but such crude solutions usually give a black precipitate with sulphydrate of ammonium, owing to the presence of iron. The latter element may be removed, however, on boiling the manganous solution with a little carbonate of sodium, which throws the ferric salt out of solution before the manganous. Pure manganous chloride may be similarly obtained on boiling the impure solution with manganous carbonate ; the latter decomposes the ferric chloride with production of ferrric hydrate and more manganous chloride, and evolution of carbonic acid gas. To the recently precipitated manganous sulphide add acetic acid; it is dissolved. This solubility enables manganese to be separated from nickel,* cobalt, and zinc, whose sulphides are insoluble in weak acetic acid. To express the fact in another way — manganese is not precipitated by sulphuretted hydrogen from a solution containing free acetic acid only. Fifth Reaction , — To solution of manganous salt add ammonia drop by drop; a white precipitate of manganous hydrate (Mn2HO) falls. Add excess of ammonia; the precipitate is dissolved. The fixed alkalies give a similar precipitate insoluble in excess. The precipitate rapidly absorbs oxygen, becomes brown, and gradu- ally passes into a higher oxide. Sixth Reaction , — Heat a little black oxide of manganese in a test-tube with sulphuric acid ; oxygen is evolved and sul- phate of manganese formed {Mangayiesii Sulphas^ XJ. 8. P.), add water, boil, filter, evaporate, and set aside to crystallize. Larger quantities are made in a similar manner. Sulphate of manganese (MnS04,5H.,0) occurs in colorless, or pale rose-colored, transparent crystals, which, when deposited from a solu- i tion at a temperature between 68^ and 86^, have the form of right ; rhombic prisms, and contain four molecules of water. This salt is - very soluble in water. The solution is not colored by tincture of nutgall a black (a black shows iron), but affords wfith caustic alkalies a white precipitate (Mn2HO), wLich, by exposure to the air, soon absorbs oxygen, and becomes brown. Sulphydrate of ammonium throws down a flesh-colored precipitate (MnS), and ferrocyanide of potassium, a white one (Mn^Fcy). |j COBALT. 201 Many other reactions occur between manganese salts and various reagents, but are of no particular synthetical or analytical interest. A good method proposed by Crum, for detecting minute quantities of manganese, consists in adding dilute nitric acid and the puce-colored oxide or per- oxide of lead to the solution, and then boiling ; a red tint, duetto permanganic acid, is imparted to the liquid. COBALT. Symbol Co. Atomic weight 58.8. Source . — Cobalt occurs sparingly in nature as the arsenide (Co AS2), or tin-white cohalt, and occasionally as a double arsenide and sul- phide (CoASg, C0S2), or cohalt-glance (from glanz, brightness, in allusion to its lustre). Uses . — It chief use is in the manufactory of blue glass, the color of which is due to a compound of cobalt. Cobalt is also the coloring constituent of smalt (from smelt, a corruption of melt), a finely-ground sort of glass used as a blue pigment by paper-stainers and others, and employed also by laundresses to neutralize the yellowish appearance of washed linen. The salts of cohalt may be obtained from the oxide (CoO), and the oxide from zajfre, a mixture of sand and roasted ore. Quant ivalence . — Cobalt often exhibits quadrivalent affinities, but still more often exerts only bivalent powers (Co"). It has analyti- cal relations with zinc, nickel, and manganese, and may be regarded as a member of the iron group. Analytical Reactions (Tests). First Analytical Reaction. — Pass sulphuretted hydrogen through a solution of a salt of cobalt — the chloride (C0CI2) or nitrate (C02NO3) for example ; no decomposition occurs. Add ammonia; the sulphydrate of ammonium thus formed causes the precipitation of black sulphide of cobalt (CoS). The moist precipitate slowly absorbs oxygen from the air, becom- ing converted into sulphate of cobalt (C0SO4). Second Analytical Reaction. — Add ammonia gradually to a cobalt solution ; a blue precipitate of impure h}- drate of cobalt (Co2HO) falls. Add excess of ammonia; the pre- cipitate is dissolved. A similar precipitate is given by the fixed alkalies, insoluble in excess. Third Analytical Reaction. — Make a borax bead by heat- ing a fragment of the salt on the looped end of a platinum wire in a blowpipe-flame until a clear transparent globule 208 RARER METALLIC RADICALS. is obtained. Place on the bead a minute portion of cobalt compound, or touch it with a drop of solution. Again fuse the borax ; a blue bead results. This is a delicate test for cobalt. From what has previously been said, it will be seen that this experiment has also considerable syn- thetical interest. Fourth Analytical Reaction, — To a solution of a salt of cobalt add two or three drops of hydrochloric acid, then excess of solution of cyanide of potassium, and boil for ten minutes ; oxygen is absorbed, and cobalticyanide of potassium (K(.Co 2 Cyj 2 ) formed. Add hydrochloric acid, and boil the mixture (in a fume-cupboard, to avoid inhalation of any hydrocyanic acid) ; the excess of cyaiiide of potas- sium is thus decomposed, but the cobaltic 3 ^anide is un- affected. Now add excess of solution of potash; the cobalticyanide of potassium is decomposed, the hydrate of cobalt formed remaining dissolved in the alkaline liquid. Nickel under similar circumstances is precipitated, the reaction thus affording means of separating these closely allied metals from each other. Other reactions between a cobalt solution and different reagents may be performed, and various precipitates ob- tained ; but these have no special analytical interest. Invisible Ink, — The salts of cobalt containing water of ciystallization are light red, the anh^^drous more or less blue. Prove this by writing some words on paper with a solution of chloride of cobalt sufficiently dilute for the characters to be invisible when dry; hold the sheet before' a fire or over a flame ; the letters at once become visible, distinct and of a blue color. Breathe on the words, or set the sheet aside for a while ; the characters are once more invisible, owing to absorption of moisture. Hence solu- tion of chloride of cobalt forms one of the so-called sym- pathetic inks, NICKEL. Symbol Ni. Atomic weight 58.8. Nickel is, chemically, closely allied to cobalt, the ores of the two metals being commonly associated in nature. Indeed it is from speiss^ an arsenio-sulphide of nickel obtained in the manufacture of smalt, a pigment of cobalt already mentioned, that most of the nickel met with in commerce is obtained. It is much used in the preparation of the white alloy known as German or nickel silver. NICKEL. 209 Quantivalence . — Nickel exerts bivalent activity (Ni") in its ordi- nary compounds. Its salts and their solutions are usually green. They are chiefly made, directly or indirectly, from the metal itself. Analytical Beactions ( Tests), First Analytical Reaction. — Pass sulphuretted hydrogen through a solution of a salt of nickel — chloride (NiClJ, nitrate (Ni 2 N 03 ), or sulphate (NiSOJ ; no decomposition occurs. Add ammonia; the sulphydrate of ammonium thus formed causes the precipitation of black sulphide of nickel (NiS). Note . — When sulphide of nickel is precipitated by the direct addition of the common yellow solution of sulphydrate of ammonium, which always contains sulphur, there is much difficulty in filtering the mixture, owing to the slight solubility of the sulphide of nickel in the reagent and the formation of some sulphate of nickel (NiS04), oxygen being absorbed from the air by the sulphide. This may be avoided by warming the mixture and using freshly-made sulphydrate of ammonium, in which the sulphide of nickel is insoluble ; or, where practicable, the salt of nickel may be precipitated from an ammo- niacal solution by sulphuretted hydrogen. Second Analytical Reaction. — Add ammonia drop by drop to a nickel solution ; a pale-green precipitate of hydrate of nickel (Ni2HO) falls. Add excess of ammonia ; the pre- cipitate dissolves. A similar precipitate is given by the fixed alkalies, insolu- ble in excess. Third Analytical Reaction, — Nickel salts color a borax bead, when hot, a reddish-yellow tint ; the reaction is not very serviceable analytically. Fourth Analytical Reaction. — To a solution of a salt of nickel add solution of cyanide of potassium ; cyanide of nickel (NiCy 2 ) is precipitated. Add excess of solution of cyanide of potassium ; the precipitate is dissolved with formation of double cyanide of nickel and potassium (NiCy2,2KCy). Next add hydrochloric acid, and boil the mixture (in a fume-cupboard), adding a little hj^drochloric acid from time to time until all smell of hydrocyanic acid has disappeared. Lastl}^, add excess of solution of potash ; hydrate of nickel is precipitated. This reaction serves for the separation of nickel from cobalt. On adding excess of hydrochloric acid to a solution containing the two metals, together with cyanide of potassium, a precipitate of cyanide of nickel and cobalticyanide of nickel occurs. By ebullition with excess of hydrochloric acid the cyanide of nickel is decomposed, 18 =*^ 210 RARER METALLIC RADICALS. chloride of nickel going into solution. On then adding excess of potash hydrate of nickel is precipitated. The cobalticyanide of nickel is not decomposed by the acid ; but it is by the alkali, its cobalt going into solution and its nickel remaitiing insoluble as hydrate. After filtering off the nickel, cobalt is detected in the filtrate by evaporating to dryness and testing the residue with borax in the blowpipe-flame. Other reactions between a nickel solution and various reagents give, in many cases, insoluble precipitates which, from their green color, are occasionally useful in distin- o'uishing nickel from allied elements. o O CHROMIUM. Symbol Cr. Atomic weight 52 . 5 . Source. — The chief ore of chromium is chrome ironstone, a mix- ture of the oxides of the metals (FeO, Cr203), occurring chiefly in the United States and Sweden. In constitution it seems to resemble magnetic iron ore (FeO, Fe203). Preparation of Red Chromate of Potassium. — On roasting the powdered ore with carbonate of potassium and nitre, yellow chro- mate of potassium (K2Cr04) is obtained ; the mass, treated with acid, yields red or bichromate (K2Cr04, Cr03) [Potassii BichromaSy U. S. P.); from this salt other chromates are prepared, and by reduction, as presently explained, the salts of chromium itself. The yellow and orange chromates of lead are largely used as pigments. Note on Constitution. — Red chromate of potassium is a somewhat abnormal salt, containing, probably, neutral chromate associated with chromic anhydride. The value of chromates as chemical reagents is alluded to in connection with chromate of barium (p. 88 ). Heated strongly in a crucible, red chromate of potassium splits up into yellow chromate, glistening oxide of chromium, and oxygen. Quantivalence. — Chromium stands in close chemical relation to iron, aluminium, and manganese. Its atom is sexivalent if the for- mula of the fluoride (CrFg) be correct. Like iron and aluminium, it is trivalent, as seen in chromic chloride (Cr.,Clg), but sometimes exerts only bivalent activity, as in chromous chloride (CrCl2). Passage of Chromium from the Acidulous to the Basylous Side of Salts. — Through an acidified solution of red chro- mate of potassium pass sulphuretted hydrogen ; sulphur is deposited, and a green salt of chromium remains in solu- tion — chloride (Cr 2 Clg) if hydrochloric acid be used, and sulphate (Cr23SOJ if sulphuric be the acid employed. Boil the liquid to expel excess of sulphuretted hydrogen, filter, ^nd reserve the solution for subsequent experiments. Alcohol, sugar, or almost any substance which is tolerably liable to oxidation, will answer as well as sulphuretted hydrogen. CHROMIUM. 211 Sulphate of chromium (Cr23S04), like sulphate of aluminium (AI23SO4), unites with alkaline sulphates to form alums, which re- semble common alum both in crystalline form and, as far as we know, in internal structure ; they are of a purple color. Reactions. Chromium as Chromic Acid^ or other Chromate . — This is the state in which chromium will usually be met with, the most common salt Seing the red chromate or bichro- mate of potassium. Mix four volumes of a cold, saturated aqueous solution of red chromate of potassium with five of oil of vitriol ; on cooling, chromic anhydride (CrOg), Acidum Chi'omicum^ U. S. P., separates in crimson needles. After well draining, the crystals may be freed from adhering sulphuric acid by washing once or twice with nitric acid : the latter may t3e removed by passing dried and slightly warmed air through a tube containing the crystals. In contact with moisture chromic anhydride takes up water and forms solution of true chromic acid (H 2 Cr 04 ). Chro- mic anhydride is a powerfully corrosive oxidizing agent. It melts between 356° and 314°. The oxygen in chromic acid and other chromates, and in mangan- ates, permanganates, black oxide of manganese and puce colored oxide of lead is in a physically different state to that in peroxide of hydrogen, peroxide of barium, and similar compounds. On bringing chromic acid or the above acidified solution of red chromate of potas- sium into contact with solution of peroxide of hydrogen, a strong effervescence of oxygen ensues. According to Schdnbein and Brodie the oxygen of chromic acid is in the negative or ozonic state, while that of peroxide of hydrogen is in the positive or antozonic condition. Both are equally active, but neutralize each other, forming neutral or ordinary oxygen. In the analytical examination of solutions containing chromates, the chromium will always come out in the state of green chromic hydrate along with ferric hydrate and alumina, the prior treatment by sulphuretted hydrogen re- ducing the molecule to the lower state, thus : — K2Cr04, CrOg + 8HC1 -f 3H^S = Cr2Cl, + 2KC1 -b 7H2O + Sg. Chromium having been found in a solution, its condition as chromate may be ascertained by applying to the original solution' salts of barium, mercury, lead, and silver. (See the various paragraphs relating to those metals.) 212 RARER METALLIC RADICALS. Ba2N03 gives yellow BaCrO^ with chromates. Ho: 22N03 “ red Hg\^GrO^ “ AgNOg ‘‘ “ Ag 2 Cr 04 “ ‘‘ ‘‘ Ag2Cr04,Cr03 with bichromates. Pb2C2H303 ‘‘ yellow PbCrO^ Mdth both. Nitrate of barium does not completely precipitate bichromates, bichromate of barium being soluble in water; the chromate of barium is insoluble in water or acetic acid, but soluble in hydrochloric or nitric acid. Mercurous nitrate does not wholly precipitate bichro- mates : mercuric nitrate or chloride only partially precipitates chro- mates, and does not precipitate bichromates. The mercurous chro- mate is insoluble, or nearly so, in diluted nitric acid. Acetate of lead precipitates chromates and bichromates, acetic acid being set free in the latter case. The silver chromates are soluble in acids and alkalies. A delicate reaction for dry chromates will be found in the formation of chlorochromic anhydride (Cr02Cl2). A small portion of the chromate is placed in a test-tube with a fragment of dry chloride of sodium and a drop or two of oil of vitriol, and the mixture heated ; red irritating fumes of chlorochromic anhydride are evolved, and condense in dark red drops on the side of the tube. Large quantities of pure distilled chlorochromic anhydride are obtained by the same reaction, the operation being conducted in a retort, with thoroughly dry materials, for the compound is decom- posed by water. It may be regarded as chromic anhydricie in which an atom of oxygen is displaced by an equivalent quantity (two atoms) of chlorine. It is not used in medicine, but is of interest to the chemical student as being an illustration of a large class of similar bodies — chloro-acidulous or chloro-anhydro compounds. Analytical Reactions of Chromium Salts (Tests). First Analytical Reaction. — To solution of a salt of chro- mium (chloride, sulphate, or chrome alum) add sulphydrate of ammonium; a bulky green precipitate of chromic hy- drate (Cr^GHO), containing a large quantity of water (7 molecules, 7H2O), is precipitated. Cr^Cl, + GAmHS + 6H2O = Cr26HO + GAmCl + 6H2S. Second Analytical Reaction To solution of a chromium salt add ammonia; chromic hydrate is precipitated, insolu- ble in excess. Third Analytical Reaction. — To solution of a chromium salt add solution of potash or soda drop by drop ; chromic hydrate is precipitated. Add excess of the fixed alkali ; TIN. 213 the precipitate is dissolved. Well boil the solution ; the chromic hj^drate is reprecipitated. Iron, Chromium, and Aluminium Salts, chemically so alike, may be separated by this reaction. Ferric hydrate is insoluble in solu- tions of the fixed alkalies, cold or hot; chromium hydrate soluble in cold but not in hot; hydrate of aluminium in both. To a solution containing all three metals, therefore, add potash or soda, stir, and filter ; the iron is thrown out : boil the filtrate, and filter : the chro- mium is thrown out : neutralize the filtrate by acid, and then add ammonia ; the aluminium is thrown out. The three hydrates are insoluble in ammonia, and may therefore be easily separated from the hydrates of the somewhat analogous metals zinc, cobalt, nickel, and manganese. Fourth Analytical Reaction , — Add a salt of chromium (either of the above precipitates of chromic oxide or the dry residue of the evaporation of a few drops of a solu- tion of a chromium salt) to a few grains of nitre and car- bonate of sodium on platinum foil, and fuse the mixture in the blowpipe-flame ; a yellow mass of chromate of potas- sium and sodium (KNaCrOJ is formed. Dissolve the mass in water, add acetic acid to decompose excess of carbonate, and apply the reagents for chromates. This is a delicate and useful reaction if carefully per- formed. TIN. Symbol Sn. Atomic weight 118'. Source. — The chief ore of tin is stannic oxide ( 81102 ), occurring in veins under the name of tinstone, or in alluvial deposits as stream- tin. The principal mines are those of Cornwall. Preparatiooi. — The metal is obtained by reducing the roasted and washed ore by charcoal or anthracite* coal at a high temperature, and is purified by slowly heating, when the pure tin, fusing first, is •run off, a somewhat less fusible alloy of tin with small quantities of arsenicum, copper, iron, or lead remaining. The latter is known as hloclc tin ; the former heated till brittle and then hammered or let fall from a height splits into prismatic fragments resembling starch or basalt, and is named dropped or grain tin. Good tin emits a crackling noise in bending, termed the cry of tin, caused by the friction of its crystalline particles on each other. Uses. — Tin is an important constituent of such alloys as pewter, Britannia metal, solder, speculum-metal, bell-metal, gun-metal, and * Anthracite (from civOpa^, anthrax, a burning coal) or stone coal differs from the ordinary bituminous or caking coal, in containing less volatile matter, and, therefore, in burning without flame. It gives a higher temperature, and from its non-caking properties is, in furnace operations, more manageable than bituminous coal. 214 RARER METALLIC RADICALS. bronze. It is very ductile, and may be rolled into plates or leaves, known as ^m/o27, varying from to of an inch in thickness. Common tin foil, however, usually contains a large proportion of lead. The reflecting surface of most looking-glasses is an amalgam of tin and mercury, produced by carefully sliding a plate of glass over a sheet of tin foil on which mercury has been rubbed, and then excess of mercury poured. Pins are made of brass wire on which tin is deposited. Tin 'plate, of which common utensils are made, is iron alloyed with tin by dipping the cleansed sheet into melted tin. Tin tacks are in reality tinned iron tacks ; a tin nail would be too soft to drive into wood. Tin maybe granulated by melting and triturating briskly in a hot mortar, by shaking melted tin in a box on the inner sides of which chalk has been rubbed, or, in thin little bells or cor- rugated fragments (Granulated Tin, B. P.), by melting in a ladle and, as soon as fluid, pouring from the height of a few feet into water. The chemical position of tin among the metals is close to that of arsenicum and antimony. Its atom is quadrivalent and bivalent. The two classes of salts are termed stannic and stannous respectively. They are all made directly or indirectly from the metal itself. Reactions having [a) Synthetical and (5) Analytical Interest. (a) Synthetical Reactions, Chloride of Tin. Stannous Chloride. First Synthetical Reaction, — Warm a fragment of tin with hydrochloric acid ; hydrogen escapes and solution of stannous chloride (SnClJ is formed. It may be retained for future experiments. One ounce of tin dissolved in three fluidounces of hydrochloric acid and one of water, and the resulting solution diluted to five fluid- ounces, constitutes the “Solution of Chloride of Tin,” B. P. Solid stannous chloride. — By evaporation of the above solution stannous chloride is obtainable in crystals (SnCl.,2H20). It is a powerful reducing agent, even a dilute solution precipitating gold, silver, and mercury from their solutions, converting ferric and cupric into ferrous and cuprous salts, and partially deoxidizing arsenic, manganic, and chromic acids. It absorbs oxygen from the air, and is decomposed when added to a large quantity of water unless some acid be present. It is used as a mordant in dyeing and calico-printing. Perchloride of Tin. Stannic Chloride. Second Synthetical Reaction, — Through a portion of the solution of the stannous chloride of the previous reaction pass chlorine gas ; solution of stannic chloride (SnClJ is formed. Or add hydrochloric acid to the stannous solu- tion, boil, and slowly- drop in nitric acid until no more TIN. 215 fumes are evolved; again stannic chloride results. Reserve the solutions for subsequent experiments. Stannic Oxide, or Anhydride, and Stannates. Third Synthetical Beaction, — Boil a fragment of tin with nitric acid, evaporate to dryness, and strongly calcine the residue ; white stannic anhydride (SnOg) is produced. Heat the stannic anhydride with excess of solid caustic potash or soda ; stannate of the alkali metal (K2Sn03 or Na.^SnOg) results. Dissolve the stannate in water, and add hydro- chloric acid ; white, gelatinous stannic acid (H^SnOg) is precipitated. Stannic acid is also obtained on adding an alkali to solution of stannic chloride; it is soluble in excess of acid or alkali. The product of the action of nitric acid on tin is also an acid, but from its insolubility in hydrochloric and other acids, is different from ordinary stannic acid. It is termed metastannic acid (from meta, beyond), and probably has a composition expressed by the formula H^oSn50i5. It is also produced on gently heating stannic acid : — 5H2Sn03 = HjoSn^Oig stannic Metastannic acid. acid. Metastannates maybe formed; their general formula is M2H8Sn50i5. Both acids yield buff-colored stannic oxide or anhydride (Sn 02 ) when strongly heated ; it is employed in polishing plate under the name of putty poivder. Stannate of sodium (Na2Sn03,4H20) is used as a mordant by dyers and calico-printers under the name of tin prepare- liquor, (b) Beactions having Analytical Interest ( Tests), STANNOUS SALTS. First Analytical Beaction. — Through a solution of a stannous salt (stannous chloride, for example, see previous page) pass sulphuretted hydrogen; brown stannous sul- phide (SnS) is precipitated. Four off the supernatant liquid, add ammonia to the moist precipitate (to neutralize acid), and lastly yellow sulphydrate of ammonium ; the precipitate is dissolved. Aqueous solution of sulphydrate of ammonium becomes yellow when a day or two old, and then contains excess of sulphur, that element having become displaced by oxygen absorbed from the air ; hence, in the above reaction, the stannous sulphide (SnS), in dis- solving, becomes stannic sulphide (SnS2) ; for the latter is precipi- tated on decomposing the alkaline liquid by an acid. 216 RAIIER METALLIC RADICALS. Second Analytical Reaction. — To solution of a stannous salt add solution of potash or soda ; white stannous hydrate falls (Sn2HO). Add excess of the alkali ; the precipitate dissolves. Boil the solution ; some of the tin is reprecipi- tated as black stannous oxide (SnO). Ammonia gives a similar precipitate, insoluble in excess. The alkaline carbonates do the same, carbonic acid gas escaping. STANNIC SALTS. Third Analytical Reaction, — Through solution of a stan- nic salt (stannic chloride, for example, see page 214) pass sulphuretted hydrogen gas ; yellow stannic sulphide (SnS.^) is precipitated. Pour off the supernatant liquid, and to the moist precipitate add ammonia (to neutralize acid), and then sulphydrate of ammonium ; the precipitate dissolves. Note. — In precipitating stannic sulphide the presence of too much hydrochloric acid must be avoided ; the formation of the precipitate is also facilitated if the solution be warmed. Stannic sulphide, like the sulphide of arsenicum and antimony, dissolves in a solution of alkaline sulphide, with formation of definite crystallizable salts. Anhydrous stannic sulphide, prepared by sublimation, has a yellow or orange lustrous appearance, and is used by decorators as bronzing-powder. It is sometimes termed mosaic gold. Fourth Analytical Reaction. — To solution of a stannic salt add potash or soda ; white stannic acid falls (HaSnOg). Add excess of the alkali ; the precipitate dissolves. Boil the precipitate ; no reprecipitation occurs — a fact enabling stannic to be distinguished from stannous salts. Ammonia gives a similar precipitate, soluble, but not readily, in excess. The fixed-alkaline carbonates do the same, carbonic acid gas escaping ; after a time the stannic salt is again deposited, pro- bably as stannate of the alkali metal. Carbonate of ammonium and acid carbonates of alkali metals give a precipitate of stannic acid insoluble in excess. Antidotes. — In cases of poisoning by tin salts (dyer’s tin liquor e. g.), solution of carbonate of ammonium should be given. White of egg is also said to form an insoluble precipitate with compounds of tin. Vomiting should be speedily induced, and the stomach pump quickly supplied. fi GOLD. I I f; j Source . — Gold occurs in the free state in nature, occasionally in'jj nodules or nuggets, but commonly in a finer state of division termedi j gold dust. \i ii GOLD 217 ■ , Preparation. — Gold is sem^ted from tlie sand, crushed quartz, ' or other earthy maj^r it may be associated, by agitation ' with water, when tl^^old, from its relatively greater specific gravity, falls to the bottom of the vessels first, the lighter mineral matter being allowed to run off with the water. From this rich sand the gold is. dissolved out by mercury, the latter filtered, and the amalgam distilled, when the mercury volatilizes and gold remains. The amal- 1 gamation may be much facilitated by the use of a small proportion of sodium, as described under silver. Pure gold is too soft for general use as a circulating medium. Gold coin is an alloy of copper and gold, that of Great Britain containing 1 of the former to 11 of the latter, or 8^ per cent, of copper, that of France, Germany, and the United States about 10 per cent. Jewel- lers^ gold varies in quality^ every 24 parts containing 18, 15, 12, or 9 parts of gold, the alloys being technically termed 18, 15, 12, or 9 carat fine. Articles made of the better qualities are usually stamped by authority. Trinkets of inferior intrinsic worth are commonly thinly coated with pure gold by electro-deposition or otherwise. Gold leafi^ nearly pure gold passed between rollers till it is about gj-^ of an inch in thickness and then hammerecfbetween sheets of animal membrane, termed gold-beater’s skin and calf-skin vellum, till it is T6?T’(yn?y or of an inch in thickness. It may even be hammered till 280,000 leaves would be required to form a pile an inch thick. Gold Coinage. — The weight of gold is expressed in Great Britain in ounces troy and decimal parts of an ounce, and the metal is always taken to be of standard fineness (11 gold and 1 alloy) unless other- , wise described. The degree of fineness of gold, as ascertained by assay, is expressed decimally, fine pure gold gold free from metallic impurities,” B. P.), being taken as unity, or 1.000. Thus gold of British standard is said to be 0.9166 fine, of French standard 0.900 fine. The legal weight of the sovereign is 0.2568 ounce of standard gold, or 123.274 grains. The weight came from one pound of stand- ard gold (5760 grains) being coined into 44^ guineas. Gold coins are legal tender to any amount, provided that the weight of each sovereign does not fall below 122.5 grains, or in the case of a half sovereign 61.125 grains ; these are the “least current” weights of the coins. Note. — In chemical analysis gold comes out among the sulphides of the metals precipitated by sulphuretted hydrogen ; and of those sulphides, it, like the sulphides of tin, antimony, and arsenicum, is soluble in sulphydrate of ammonium. Quantivalence. — Gold is trivalent (An”'), but in some compounds univalent (Au'). Reactions. Synthetical Reaction , — Place a fragment of gold {e. gold leaf) in ten or twenty drops of aqua regia (a mixture of one part of nitric and two or three of hydrochloric acid), and set the test-tube aside in a warm place ; solution of percliloride of gold or auric chloride (AUCI3) results. 19 218 RARER METALLIC RADICALS. When the metal is dissolved, evaporate nearly to dryness to remove most of the excess of fluid, dilute with water, and retain the solution for subsequent experiments. Sixty grains of gold treated thus, and the resulting chloride dis- solved in flve ounces of distilled water, constitutes ‘‘ Solu- tion of Chloride of Gold,’’ B. P. Au, + 2 HNO 3 + 6HC1 = 2 AUCI 3 + 2X0 + 4H,0 This reaction has analytical interest also ; for in examining a sub- stance suspected to be or contain metallic gold, solution would have to be effected in the above way before reagents could be applied. Gold is insoluble in hydrochloric, nitric, and the weaker acids. Analytical Reactions {Tests), First Analytical Reaction, — Through a few drops of so- lution of an auric salt (the chloride, AuClg, is the only convenient one) pass sulphuretted hydrogen ; brown auric sulphide (Ail^S 3 ) is precipitated. Filter, wash, and add sulphydrate of ammonium ; the precipitate dissolves. Second Analytical Reaction, — To solution of a salt of gold add ferrous chloride or sulphate, and set the tube aside ; metallic gold is precipitated, a ferric salt remaining in solution. This is a convenient way of preparing pure gold, or fine gold as it is termed, or of working up the gold residues of laboratory opera- tions. The precipitate, after boiling with hydrochloric acid, washing, and drying, may be obtained in a button by mixing with an equal Aveight of borax or acid sulphate of potassium and fusing in a good furnace. Third Analytical Reaction, — Add a few drops of dilute solutions of stannous and stannic chloride to a consider- able quantity of distilled water; pour the liquid, a small! quantity at a time, into a dilute solution of auric chloride (AuCy, well stirring; the mixture assumes a purple tint,! and flocks of a precipitate, known as the Purple of Cassius,} (from the name of the discoverer, M. Cassius), are jiroduced.* The same compound is formed on immersing a piece of tin foil in ^ solution of auric chloride ; it is said to be a mixture of auric, aurous, | stannic, and stannous oxides. It is the coloring agent in the finer varieties of ruby glass. [ PLATINUM. 219 PLATINUM. Symbol Pt. Atomic weight 198. Source. — Platinum, like gold, usually occurs in nature in the free state, the chief sources of supply being Mexico, Brazil, and Siberia. It is separated from the alluvial soil by washing. Uses . — The chief use of platinum is in the construction of foil, wire, crucibles, spatulas, capsules, evaporating-dishes, and stills, for the use of the chemical analyst or manufacturer. It is tolerably hard, fusible with very great difficulty, not dissolved by hydrochloric, nitric, or sulphuric acid, and only slightly affected by alkaline substances. It is attacked by aqua regia with production of perchloride of plati- num or platinic chloride (PtCl^). It forms fusible alloys with lead and other metals, and with phosphorus a phosphide, which easily melts. Neither of these substances, therefore, nor mixtures which may yield a metal, should be heated in platinum vessels. The chemical position of platinum among the elements is close to that of gold. Its atom is quadrivalent in some compounds, in others apparently bivalent (Pt"). The higher salts are termed j)/a- tinic, the lower platinous. Reactions. Perchloride of Platinum. Platinic Chloride. Synthetical Reaction, — Place a fragment of platinum in a little aqua regia and set the vessel aside in a warm place, adding more acid from time to time if necessary; solution of perchloride of platinum (PtClJ results. Evaporate the solution to remove excess of acid, and complete the desic- cation over a water-bath. Dissolve the residue in water and retain the solution for subsequent experiments, and as a reagent for the precipitation of salts of potassium and am- monium. A quarter of an ounce of platinum treated in the above manner, and the resulting chloride dissolved in five ounces of water, consti- tutes “Solution of Perchloride of Platinum,” B. P. This reaction has analytical interest also; for in examining a sub- stance suspected to be or to contain metallic platinum, solution would have to be thus effected before reagents could be applied. Analytical Reactions ( Tests). First Analytical Reaction. — Through a few drops of a solution of a platinic salt (PtCl^ is the only convenient one) to which an equal quantity of .solution of chloride of sodium has been added, pass sulphuretted hydrogen; dark brown 220 RARER METALLIC RADICALS. platinio sulphide (PtS.^) is precipitated. Filter, wash, and add sulphj'drate of ammonium ; the precipitate dissolves. If chloride of sodium be not present in the above reaction, the pre- cipitated sulphide will contain platinous chloride, and detonate when heated. Second AnoXytical Reaction , — Add excess of solution of carbonate of sodium and some sugar to solution of per- chloride of platinum and boil ; a precipitate of metallic pla- tinum falls. Platinum Black (B. P.) is the name of this precipitate. It pos- sesses in a high degree a quality common to many substances, but largely possessed by platinum, namely, that of absorbing or occluding gases. In its ordinary state, after well washing and drying, it ab- sorbs from the air and retains many times its bulk of oxygen. A drop of ether or alcohol placed on it is rapidly oxidized, the plati- num becoming hot. This action may be prettily shown by pouring a few drops of ether into a beaker (one having portions of the top and sides broken off answers best), loosely covering the vessel with a card, and suspending within the beaker a platinum wire, one end being attached to the card by passing through its centre, the other terminating in a short coil or helix near the surface of the ether ; on now warming the helix in a flame and then rapidly introducing it into the beaker, it will become red-hot and continue to glow so long as there is ether in the vessel. In this experiment real combustion goes on between the ether vapor and the concentrated oxygen of the air, the products of the oxidation revealing themselves by their odor. Third Analytical Reaction , — To solution of perchloride of platinum add solution of chloride of ammonium ; a yel- low granular precipitate of double chloride of platinum and ammonium (PtCl^, 2AmCl) falls. When slowly formed in dilute solutions, the precipitate is obtained in minute orange prisms. Chloride of potassium (KOIJ gives a similar precipitate (PtCh 2KC1). Platinic chloride having been stated to be a test for potas- sium and ammonium salts, the reader is prepared to find that potas- sium and ammonium salts are tests for platinic salts. The double sodium compound (PtC1^2NaCl) is soluble in water. Collect tlie precipitate, dry, and heat in a small crucible ; it is decomposed, and metal, in the finely divided state of spongy platinum,^ remains. 3(PtCl,2NII^Cl) = Pt3 -f 2NII,C1 -f IGIICI -f 2'^,. Heat decomposes the potassium salt into Pt -P 2KCl-f-Cl4, the chlorine escaping and the chloride of potassium remaining with the platinum. C A D M I U xM . 221 In working up the platinum residues of laboratory operations, the mixture should be dried, burnt, boiled successively with hydro- chloric acid, water, nitric acid, water, then dissolved in aqua regia, excess of acid removed by evaporation, chloride of ammonium added, the precipitate washed with water, dried, ignited, and the resulting spongy platinum retained or converted into perchloride for use as a reagent for alkali-metals. It is by this process that the native pla- tinum is treated to free it from the rare metals palladium, rhodium, osmium, ruthenium, and iridium. The spongy platinum is converted into the massive condition by a refinement on the blacksmith’s pro- cess of welding (German wellen, to join), or by fusing in a flame of pure oxygen and hydrogen gases — the oxyhydrogen blowpipe. Occlusion by Spongy Platinum. — Spongy platinum has great power of occlusion. A small piece held in a jet of hydrogen causes ignition of the gas, owing to the close approximation of particles of oxygen (from the air) and hydrogen. Dobereiner’s lamp is con- structed on this principle — the apparatus being essentially a vessel in which hydrogen is generated by the action of diluted sulphuric acid on zinc, and a cage for holding the spongy platinum. CADMIUM. Symbol Cd. Atomic weight 112. In most of its chemical relations cadmium ( Cadmium, U. S. P.) re- sembles zinc. In nature it occurs chiefly as an occasional constituent of the ores of that metal. In distilling zinc containing cadmium, the latter, being the more volatile, passes over first. In analytical operations cadmium, unlike zinc, comes down among the metals pre- cipitated by sulphuretted hydrogen ; that is, its sulphide is insoluble in dilute hydrochloric acid, while sulphide of zinc is soluble. It is a white malleable metal nearly as volatile as mercury. Sp. gr. 8.7. Beyond the occasional employment of the sulphide as a pigment ijaune brillant). and the iodide in photography and medicine, cad- mium and its salts are but little used. The atom of cadmium is bivalent (Cd"). Reactions. Iodide of Cadmium. First Synthetical Reaction . — Digest metallic cadmium in water in which a fragment of iodine is placed, until the color of the iodine disappears ; solution of iodide of cad- mium (Gadmii lodidum^ B. P.) (Cdl 2 ) remains. Pearly micaceous crystals may be obtained on evaporating the solution. This is the process alluded to in the British Pharmacopoeia. The compound is used in medicine in the form of ointment, tfnguentum Cadmii lodidi, B. P. The salt is also employed, with other iodides, 19 * 222 RARER METALLIC R A P I C A L S . in iodizing collodion for photographic purposes. It melts when heated, and is soluble in water or spirit, the solution reddening litmus paper. Sulphate of Cadmium. Second Synthetical Reaction, — Dissolve cadmium in nitric acid; pour the resulting solution of nitrate of cadmium (Cd2N03) into a solution of carbonate of sodium ; dissolve the precipitate of carbonate of cadmium (CdCOg) in dilute sulphuric acid, separate and crystallize. Sulphate of cad- mium (CdSOj is a white crystalline salt soluble in water, (U. S. P.). First Analytical Reaction, — Through solution of a cad- mium salt (Cdl2 or CdCl,^) pass sulphuretted hydrogen; a 3^ellow precipitate of sulphide of cadmium (CdS) falls, re- sembling in appearance arsenious, arsenic, and stannic sulphides. Add sulphydrate of ammonium ; the precipitate, unlike the sulphides just mentioned, does not dissolve. Sulphides of cadmium and copper may be separated by solution of cyanide of potassium, in which sulphide of copper is soluble and sulphide of cadmium insoluble. Second Analytical Reaction, — To a cadmium solution add solution of potash; white hydrate of cadmium (Cd 2 HO) is precipitated, insoluble in excess of the potash. Hydrate of zinc (Zn2HO), precipitated under similar circum- stances, is soluble in solution of potash ; the filtrate from the hydrate of cadmium may therefore be tested for any zinc occurring as an impurity by applying the appropriate reagent — sulphydrate of am- monium. Before the blowpipe- fiame,^ on charcoal, cadmium salts give a brown deposit of oxide of cadmium (CdO). BISMUTH. Symbol Bi. Atomic weight 208. Source . — Bismuth occurs in the metallic state in nature. It is freed from adherent quartz, etc., by simply heating, when the metal melts, runs off, and is collected in appropriate vessels. It is also met with in combination with other elements. Bismuth is grayish-white, with a distinct pinkish tinge. Uses . — Beyond the employment of some of its compounds in medi- cine, bismuth is but little used. Melted bismuth expands considerably on solidifying, and hence is valuable in taking sharp impressions of dies. It is a constituent of some kinds of type-metal and of pewter- solder. BISMUTH. 223 The position of bismuth among the metals is close to that of arse- nicum and antimony. ‘ Its atom is rarely quinquivalent (Bi’^) ; but in most compounds trivalent (Bi'"). Reactions having (a) Synthetical and (6) Analytical Interest. (a) Reactions having Synthetical Interest, Nitrate of Bismuth. First Synthetical Reaction, — To a few drops of nitric acid and an equal quantity of water in a test-tube, add a little powdered bismuth, heating the mixture if necessary; nitric oxide (NO) escapes, and solution of nitrate of bismuth (BiSNOg) results. Bi, + 8HNO3 = 2(Bi3N03) + 2NO + Bis- Nitric acid. Nitrate of Nitric Water. muth. bismuth. oxide. The solution evaporated gives crystals (BiSNO^, 5H^O), any arse- nicum which the bismuth might contain remaining in the mother- liquor. Native bismuth [Bismuthum, B. P. and U. S. P.) commonly contains arsenicum, most of which is removed by roasting or by fus- ing two or three times with a tenth of its weight of nitre [Bismuthum Purificatum, B. P.), or, finally, by converting the metal into oxyni- trate, as described in the next reaction, and reducing this with char- coal at a high temperature. To make nitrate of bismuth and other salts on a larger scale, 2 ounces of the metal, in small fragments, are gradually added to a mixture of 4 fluidounces of nitric acid and 3 of water, and, when effervescence (due to escape of nitric oxide) has ceased, the mixture heated for ten minutes, poured off from any insoluble matter, eva- porated to 2 fluidounces to remove excess of acid, and then either set aside for crystals to form, poured into half a gallon of water to form the oxynitrate of bismuth, or into a solution of 6 ounces of carbonate of ammonium in a quart of water to form the oxycarhonate as de- scribed in the following reactions. The precipitates should be washed with cold water and dried at a temperature not exceeding 150° F. Exposed in the moist state to 212° for any length of time, they undergo slight decomposition. Subnitrate or Oxynitrate of Bismuth. Second Synthetical Reaction, — Pour some of the above solution into a considerable quantity of water ; decompo- sition occurs and oxynitrate of bismuth (BiONO.^) in a hydrous state (Bi0N03, H^O) {Bismuthi Suhnitras^ B. P.) is precipitated : — Bi3N03 + = Bi 0 N 03 + 2 HNO 3 Nitrate of Water. Oxynitrate of Nitric acid. bismuth. bismuth. 224 RARER METALLIC RADICALS. Filter, and test the filtrate for bismuth by adding excess of carbonate of sodium; a precipitate shows that some bismuth remains in solution. The following equation, therefore, probably more nearly represents the decompo- sition : — 5(Bi3N03) -f 8H,0 = 4(Bi0N03, H,0) + Bi3N03,8HN03 Nitrate of Water. Oxy nitrate of Nitrate of bismuth bismuth. bismuth. iu acid. Decomposition of nitrate of bismuth by water is the process of the British Pharmacopoeia for the preparation of oxynitrate or “sub- nitrate” of bismuth for use in medicine. For this purpose the original metal must contain no arsenicum. In manufacturing the compound, therefore, before pouring the solution of nitrate into water, the liquid should be tested for arsenicum by one of the hydro- gen tests ; if that element be present, the solution must be evaporated and only the deposited crystals be used in the preparation of the oxynitrate. For on pouring an arsenical solution of nitrate of bis- muth into water, the arsenicum is not wholly removed in the super- natant liquid, unless the oxynitrate be redissolved and reprecipitated several times, according to the amount of arsenicum present. In the United States Pharmacopoeia the solution of nitrate (made from washed carbonate) is directed to be poured into dilute solution of ammonia. Such a product will probably contain more oxhydrate than oxynitrate. Suhnitrate of Bismuth is sometimes administered in the form of a lozenge {Trochisci Bismuthi, B. P.). It is used as a cosmetic under the name of Fearl-ivhite {Blanc de Perle). Oxy salts of Bismuth. — It will be noticed that the formula for subnitrate of bismuth (BiNO^) does not accord with that of other nitrates, the characteristic elements of which are NO^. Analogy would seem to indicate, however, that the fourth atom of oxygen has different functions to the three in the NO3; for on pouring solution of chloride of bismuth (BiCb) into water, oxychloride is produced (BiOCl) (a white powder used as a cosmetic, also in enamels, and in some varieties of sealing-wax). The bromide (BiBrg) and iodide (Bilg) similarly yield oxybromide (BiOBr) and oxyiodide (BiOI). The subnitrate (BiN04) is, therefore, probably an analogous com- pound, an oxynitrate (BiONOg). The sulphate (Bi23S04) also de- composes when placed in water, giving what may be termed an oxysulphate (Bi202S04). It is difficult to prove whether or not the water in the “subni- trate” or hydrous oxynitrate of bismuth (BiONOg, II.^O) is an inte- gral part of the salt. If it is, the compound is simply the hydrato- nitrate (BiNOg2HO) of bismuth. Subcarbonate or Oxycarbonate of Bismuth. Thii'd Synthetical Reaction , — To solution of nitrate of bismuth add carbonate of ammonium ; ^white precipitate BISMUTH. 225 of hydrous oxycarbonate (2Bi202C03, HgO) (Bisniuihi Gar- honas^ B. P.) falls. 4(Bi3N03) + = 12 NH,N 03 + Nitrate of “ Carbonate” of Nitrate of bismuth. ammonium. ammonium. + too. Carbonic acid gas. According to the United States Pharmacopoeia the 0x3^- carbonate (Bismuthi Subcarbonas) is made by precipitating with carbonate of sodium a solution of the nitrate prepared from washed hydrate of bismuth. This compound may be regarded as similar in constitution to the oxysaltsjust described. luBi^COg one scarcely recognizes the char- acteristic elements of carbonates ; but considering the preparation to be an oxycarbonate (Bi202C03) its relations to carbonates and oxides are evident. These subsalts may all be viewed as normal bismuth salts in which an atom of oxygen replaces an equivalent proportion of other acidulous atoms or radicals : — Chloride Bi 3 Cl Oxychloride . BiOCl Bromide BiSBr Oxybromide . BiOBr Iodide Bi 3 I Oxyiodide . . BiOI Nitrate Bi3N03 Oxynitrate . BiONOg Sulphate Bi 23 SO^ Oxysulphate . Bi 202 S 0 ^ Carbonate (unknown) BigSCOg Oxycarbonate Bi202C03 They may be viewed, in short, as salts in process of conversion to oxide ; continue the substitution a little further, and each yields oxides of bismuth (Bi203). They have also been considered to be salts of a hypothetical univalent radical bismuthyl (BiO). Citrate of Bismuth. Fourth Synthetical Reaction. — To solution of nitrate of bismuth add citric acid and then solution of ammonia until the precipitate at first formed is redissolved, and the liquid after shaking has a slight ammoniacal odor. The product contains citrate of bismuth (BiCgH^O., H^O ?) dissolved in solution of citrate and nitrate of ammoniu-m. Made with definite quantities of ingredients and an amount of bismuth salt equivalent to the three grains of oxide (Bi203) in a fluidrachm, the solution forms the Liquor Bismuthi et Am- monise Citratis.^ B. P. (b) Reactions having Analytical Interest ( Tests). First AnalyticcRr-Reaction. — Through solution of a bis- muth salt (a slightly acid solution of nitrate, for example) 2Bi202C03 Oxycarbonate of bismuth. 226 RARER METALLIC RADICALS. pass siilpliu retted hydrogen ; a black precipitate of sulphide of bismuth falls. Add ammonia (to neutralize acid) and then sulphydrate of ammonium ; the precipitate, unlike As^^Sg and Sb.^Sg, is insoluble. Second Analytical Reaction . — Concentrate almost any acid solution of a bismuth salt and pour into water ; a white salt is precipitated. This reaction is characteristic of bismuth salts ; it has already been amply explained. The precipitate is distinguished from one formed by antimony under similar circumstances, by being insoluble in solution of tartaric acid. The reader is again advised to trace out the exact nature of each of the foregoing reactions, chiefly by aid of equations or diagrams. QUESTIONS AND EXERCISES. 343. Enumerate the fifteen metals, salts of which are frequently employed in pharmacy. 344. Mention the eleven rarer metals. 345. Name the sources and official compounds of lithium. 346. Give an equation explanatory of the formation of Citrate of Lithium. 347. What is the strength of Liquor Litliice Effervescens f 348. On what chemical hypothesis are lithium compoufids admi- nistered to gouty patients ? 349. Describe the relation of lithium to other metals. 350. What is the chief test for lithium ? 351. Write a paragraph on strontium, its natural compounds, chemical relations, technical applications, and tests. 352. What are the formulae and properties of oxalate of cerium ? 353. Name the commonest ore of manganese, and give an equation descriptive of its reaction with hydrochloric acid. 354. Explain the formation of permanganate of potassium, employ- ing diagrams or equations. 355. In what manner do the manganates of potassium act as dis- infectants ? 356. What are the chief tesW^r manganese ? 357. What are the chief use?^ the compounds of cobalt ? 358. IIow are salts of cobalt analytically distinguished from those of nickel ? 359. Mention an application of nickel in the arts. 360. What is the general color of nickeL^^alts ? 361. State the method of preparation of red chromate of potassium. 362. Give the formulae of red and yellow chromates of potassium. 363. How is red chromate of potassium obtained ? QUESTIONS AND EXERCISES. 227 364. Describe the action of sulphuretted hydrogen on acidified solutions of chromates. 365. What is the formula of chrome alum ? 366. Mention the chief tests for the chromic radical, and for chro- mium. 367. How would you detect iron, chromium, and aluminium in a solution ? 368. Define the terms tinstone, stream-tin, block-tin, grain-tin, tin- plate. 369. Describe the position occupied by tin in relation to other metals. 370. What is the difference between stannic acid and metastannic acid ? 371. State the applications of tin in the arts. 372. Mention the chief tests for stannous and stannic salts. 373. Name the best antidote in cases of poisoning by tin solutions. 374. How is gold dust separated from the earthy matter with which it is naturally associated? 375. How much pure gold is contained in English coin, and in jewellers’ gold ? 376. State the average thickness of gold leaf. 377. What is the weight of a sovereign ? 378. Explain the term ‘‘fineness” as applied to gold. 379. What effect is produced on gold by hydrochloric, nitric, and nitrohydrochloric acids respectively ? 380. By what reagents is metallic gold precipitated from solutions of its salts ? 381. How is Purple of Cassius prepared ? 382. Whence is platinum obtained ? 383. Why are platinum utensils peculiarly adapted for use in che- mical laboratories ? 384. How is perchloride of platinum prepared ? - 385. Name the chief tests for platinum. 386. What is “platinum black”? 387. Describe an experiment demonstrative of the large amount of attraction for gases possessed by metallic platinum. 388. How is “ spongy platinum” produced ? 389. By what process may the metal be recovered from platinum residues ? 390. What is occlusion in chemistry? 391. In what condition does cadmium occur in nature ? 392. By what process may Iodide of Cadmium be prepared ? and in what form is it used in medicine^ 393. Mention the chief test for fcil^iium. 394. Distinguish sulphide of cadmium from other sulphides of similar color. * 395. How is cadmium separated from zinc ? 396. How does bismuth ocmir in nature ? 397. What is the quantivalence of bismuth ? 398. Write down equations descriptive of the action of nitric acid on bismuth, and water on nitrate of bismuth. 228 RARE«, METALLIC RADICALS. 399. How may pure salts be prepared from bismuth containing arsenicum ? 400. Give a diagram of the process for the so-called Carbonate of Bismuth. 401. Write formulae showing the accordance of the official Subni- trate and Carbonate with the other salts of Bismuth, and with or- dinary Nitrates and Carbonates. 402. How is Liquor Bismuthi et Ammonice Citratis prepared ? 403. What are the tests for Bismuth? Practical Analysis. Bismuth is the last of the metals whose synthetical or analytical relations are of general interest. The position of the rarer among the common metals, and the influence which either has on the other during the manipulations of analysis, will now be considered. These objects will be best accomplished, and a more intimate acquaintance wdth all the metals be obtained, by analyzing, or studying the methods of analyzing, solutions containing one or more metallic salts. Of the following 4'ables, the first (1) includes directions for the analysis of an aqueous or only slightly acid solution containing but one salt of any of the metals hitherto considered. Here the color of the precipitate or precipitates afforded by a metal under given cir- cumstances must be relied on to a considerable extent in attempting the detection of the various elements. The second Table (2) is intended as a chart for the analysis of solutions containing salts of more than one of the common and rarer metals. It is simply a compilation from the foregoing reactions — an extension of the scheme for the analysis of salts of the ordinary metals. Hence it often may be altered or varied in arrangement to suit the requirements of the analyst. The third (3) is a mere outline of the preceding Tables. It gives the position of the metals in relation to,each other, and will much aid the memory in recollecting that relation. 2 ) OF SHORT DIRECTIONS FOR APPLYING SOME OF THFFOR iiydrocliloric acid. )F Precipitate Hg(bus) Pb Ag. boil with water, filter. recipilate Hg Ag. , add AmHO. 5L Filtrate Ag. AddHNOs. White ppt. See also p. 231. Filtrate Pb. Add H2SO4. White ppt. » c Cu Precipii te Cd Cu Ag Pb As Collect, wash, digest in A Precipitate Cd Cu Hg Pb Bi. Wash, boil in H^Os, filter. ■'a (idi] Ppt. Filtrate Hg. Cd Cu Pb Bi. sol. ■ Black. Add AmHO. filter. IS. Confirm Y llo\\ by Cu iSrn test in Precipitate Filtrate hS Flei original Pb Bi. Cd Cu m un’i“ solution. Wash, add a few Add KCy and 8t. drops HNO3, ILS. - dilute, filter. n Ppt. Filt. Ppt. Filt. Bi. Pb. Cd. Cu At ape ^ Dilute, Yellow Acidify add with 1 H,S04, HC3H3O3 :i set aside ; Brown X white ppt. ppt. * See also p. 232 . ^ Jr 1 J I ANALYTICAL CHART FOR METALS. 229 230 RARER METALLIC RADICALS. 3. OUTLINE OF THE PRECEDING TABLES. HCl H^S AmHS Am^COg Am JIAsO^ Hg Cd I Zn 1 d Ba Mg K (as mercurous g salt) Cu <£3 Pb (some) Hg a <£5 Mn d ® 3 d Sr Na (as mer- curic salt) d 2 Co ' 3 oc Ca Am d Ag Pb , o ra d 3 (a little) Ni Bi As A1 ' d (as arse- B nious or < L arsenic o salt) Fe Sb CO K 1 1 a Sn (as stan- nous or ® 3 Cr , 3 £ stannic d salt) 3 03 All Pt The laboratory student should practise the examination of aqueous solutions of salts of the above metals until able to analyze with facility and accuracy. Memoranda relating to the preceding Analytical Tables. General Memoranda. These charts are constructed for the analysis of salts more or less soluble in water. The student has still to laarlTlfB^^ substances insoluble in water are to be brought into a state of solution; but once 'H' dissolved, their analysis is effected by the same scheme as tlnix just ^ given. The second Table may therefore be regarded as fairly jepre- 'senting the method by which metallic constituents of chemical Vib- are separated from each other and recognized. The ANALYTICAL MEMORANDA. 231 metliods of isolation of the complementary constituent of the salt (the reactions of non-metals and acidulous radicals) will form the next object of practical study. The group-tests adopted in the Tables are, obviously, hydrochloric acid, sulphuretted hydrogen, sulphydrate of ammonium, carbonate of ammonium, and arseniate of ammonium. If a group-test produces no precipitate, it is self-evident that there can be no member of the group present. At first, therefore, add only a small quantity of a group-test, and if it produces no effect add no more ; for it is not advisable to overload a solution with useless reagents ; substances expected to come down as precipitates are not unfrequently held in the liquid by excess of acid, alkali, or strong aqueous solution of some group reagent, thoughtlessly added. Indeed, experienced mani- pulators not unfrequently make preliminary trials with group-reagents on a few drops only of the liquid under examination ; if a precipitate is produced, it is added to the bulk of the original liquid and the addition of the group-reagent continued ; if a precipitate is not pro- duced, the few drops are thrown away and the unnecessary addition of a group-reagent thus avoided altogether, an advantage fully making up for the extra trouble of making a preliminary trial. While shunning excess, however, care must be taken to avoid defi- ciency ; a substance only partially removed from solution through the addition of an insufficient amount of a reagent will appear where not expected, be consequently mistaken for something else, and cause much trouble ; this will not occur if the appearance, odor, or reaction of the liquid on test-paper be duly observed. It is also a good plan, when a group-reagent has produced a precipitate and the latter has been filtered out, to add a little more of the reagent to the clear filtrate ; if more precipitate is produced, an insufficient amount of the group-test was introduced in the first instance ; but the error is corrected by simply refiltering ; if no precipitate occurs, the mind is satisfied and the way cleared for further operations. Group-precipitates, or any precipitates still requiring examina- tion, should, as a rule, be well washed before further testing ; this is to remove the aqueous solution of other substances adhering to the precipitate (the mother-liquor as it is termed), so that subsequent reactions may take pladb fairly between the reagent used and the precipitate only. A precipitate is sometimes in so fine a state of division as to retard filtration by clogging the pores of the paper, or even to pass through the filter altogether ; in these cases the mixture may be warmed or boiled, which usually causes aggregation of the particles of a precipitate, and hence facilitates the passaged liquids. Division of Work. — It is imm^flerial whether a solution be first divided into group-precipitates or each precipitate be examined as soon as produced; if the former method be adopted, confusion will be avoided by labelling or marking the funnels or papers holding the precipitate “ the HCl ppt.,” “ the H.^S ppt.,” and so on. The colors and general appearance of the various sulphides and hydrates precipitated should be borne in mind, as the absence of other bodies, as well as the presence of those thrown down, is often at once thus indicated. For example, if a precipitate by.sulphydrate f 232 THE METALLIC RADICALS. of ammonium is white, neither cobalt, nickel, nor iron can be present, and only small quantities of manganese and chromium. Applzcatzons of confirmatory tests must be frequent. Results of analyses should be recorded neatly in a memorandum- book. The various reactions which occur in an analysis have already come before the reader in going through the tests for the individual metals or in other analytical operations, it is unnecessary, therefore, again to draw out equations or diagrams. But the reactions should be thought over, and, if not perfectly clear to the mind, be written out again and again till thoroughly understood. Special Memoranda. The hydrochloric-acid precipitate may at first include some anti- mony and bismuth as oxychlorides, readily dissolved, however, by excess of acid. If either of these elements be present the wash- ings of the precipitate will probably be milky ; in that case add a few drops of hydrochloric acid, which will clear the liquid and make way for the application of the test for lead. The sulphuretted-hydrogen precipitate maybe white, in which case it is nothing but sulphur ; for, as already indicated, ferric salts are reduced to ferrous, and chromates to the lower salts of chromium by sulphuretted hydrogen, sulphur being deposited: — 2Fe,Cl6 + 2 H 2 S = 4FeCl2 + 4HC1 + ; 4H2CrO, + 6 H 2 S + 12H01 = 2 Cr,Cl 6 + 16H,0 + SS^. The proportion of the sulphuretted-hydrogen precipitate dis- solved by sidphydrate of ammonium may include a trace of copper, sulphide of copper being not altogether insoluble in sulphydrate of ammonium. On adding hydrochloric acid to the sulphydrate-of- ammonium solution, a white precipitate of sulphur only may be pre- cipitated, the sulphydrate of ammonium nearly always containing free sulphur. Carbonate of ammonium does not readily dissolve small quantities of sulphide of arsenicum out of much sulphide of antimony ; and, on the other hand, carbonate of ammonium takes into solution a small quantity of sulphide of antimony if much sul- phide of arsenicum is present. The precipftate or the original solu- tion should therefore always be examined by the other tests for these elements if any doubt exists concerning the presence or absence of either. Tin remains in the hydrogen-bottle in the metallic state, deposited as a black powder on the zinc used in the experiment. The contents of the bottle are turned out into a dish, ebullition con- tinued until evolution of hydrogen ceases, and the zinc is taken up by the excess of sulphuric acid employed ; any tin is then filtered out, washed, dissolved in a few drops of hydrochloric acid, and the liquid tested for tin by the usual reagents. The portion of the sulphur etteddiydrogen precipitate not dis- solved by the sulphydrate of ammonium may leave a yellow scrni- fused globule of sulphur on boiliilg with nitric acid. This globule may be black, not only from presence of mercuric sulphide, but also from inclosed particles of other sulphides protected by the sulphur ANALYTICAL MEMORANDA. 233 from the action of the acid. It may also contain sulphate of lead, produced by the action of nitric acid on sulphide of lead. In cases of doubt the mass must be removed from the liquid, boiled with nitric acid till dissolved, the solution evaporated to remove excess of acid, and the residue examined ; but usually it may be disregarded. In testing for lead by sulphuric acid the liquid should be diluted and set aside for some time. Mercury may also be isolated by digesting the sulphuretted-hydro- gen precipitate in sulphydrate of sodium instead of sulphydrate of ammonium. The sulphides of arsenicum, antimony, tin, and mer- cury are thus dissolved out. The mixture is then filtered, excess of hydrochloric acid added to it, and the precipitated sulphides collected on a filter, washed, and digested in sulphydrate of ammonium ; sul- phide of mercury remains insoluble, while the sulphides of arsenicum, antimony, and tin are dissolved. By this method copper also ap- pears in its right place only, sulphide of copper being quite insoluble in sulphydrate of sodium. The other metals are then separated in the usual way. The sul])liy dr at e-of -ammonium precipitate may, if the original solution was acid, contain Phosphates, Oxalates, Silicates, and Bo- rates of Barium, Calcium, and Magnesium. These will subsequently come out with the iron, and, being white, give the iron precipitate a light-colored appearance ; their examination must be conducted sepa- rately, by a method described subsequently in connection with the treatment of substances insoluble in water. Precipitates contain- ing aluminium, iron, and chromium often carry down some manga- nese, which afterwards comes out with the iron. This manganese may be detected by w^ashing the ferric hydrate to remove all trace of chlorides, boiling with nitric acid, adding puce-colored oxide .of lead, and setting the vessel aside; permanganic acid is formed, recog- nized in the clear liquid by its purple tint. Sulphide of nickel is not easily removed by filtration (^vide p. 209) until most of the excess of sulphydrate of ammonium has been dissipated by prolonged ebul- lition. The carhonate-of -ammonium precipitate may not contain the whole of the barium, strontium, and calcium in the mixture, unless free ammonia be present; for the carbonates of those metals are solu- ble in w^ater charged with carbonic acid. If, therefore, the liquid is not distinctly ammoniacal, solution of ammonia should be added. Neither carbonate nor hydrate of ammonium wholly precipitates magnesian salts ; and as a partial precipitation is undesirable, a sol- vent, in the form of an alkaline salt (chloride of ammonium), if not already in the liquid, should be added. Lithium. — The search for lithium may usually be omitted. Should a precipitate, supposed to be due to lithium, be obtained, it must be tested in a flame ( = scarlet tint), as a little magnesium not unfre- quently shows itself under similar circumstances. Spectral Analysis. — If present only in minute proportions, the lithium may also remain with the alkalies; it can then only be de- tected by physical analysis (by a prism) of the light emitted from a tinged flame — by, in short, an instrument termed a spectroscope. 20 * 234 THE METALLIC RADICALS. Such a method of examination is called spectral analysis, a subject of much interest and of no great difficulty, but scarcely within the range of Pharmaceutical Chemistry ; it will be briefly described in connection with the methods of analyzing solid substances. QUESTIONS AND EXERCISES. 404. Describe a general method of analysis by which the metal of a single salt in a solution could be quickly detected. 405. Give illustrations of black, white, light pink, yellow, and orange sulphides. 406. Mention the group-tests generally employed in analysis. 407. Under wdiat circumstances may a hydrochlonc precipitate contain antimony or bismuth ? 408. If a sulphuretted-hydrogen precipitate is white, what sub- stances are indicated ? 409. Give processes for the qualitative analysis of liquids contain- ing the following substances : — a. Arsenicum and Cadmium. h. Bismuth and Antimony. c. Ferrous and Ferric salts. d. Aluminium, Iron, and Chromium. e. Arsenicum, Antimony, and Tin. f. Lead and Strontium. g. Iron and Phosphate of Calcium. li. Mercury, Manganese, and Magnesium. i. Zinc, Manganese, Nickel, and Cobalt. j. Barium, Strontium, and Calcium. THE ACIDULOUS RADICALS. 235 THE ACIDULOUS RADICALS. Introduction. — The twenty-six radicals which have up to this point mainly occupied attention are (admitting ammonium, NH^) metals ; and they have been almost exclusively studied not in the free state, but in the condition in which they exist in salts. Moreover these metals have been treated as if they formed the more important constituent, the stronger half, the foundation or base, of salts. At- tention has been continuously directed to the metallic or hasylous side of salts. There is, indeed, still one more basylous radical worthy of a passing notice, though it is usually supposed to play only a sub- ordinate part in reactions — Hydrogen. Unlike the salts of most metals, those of hydrogen (the so-called acids) are never, in medicine or the arts generally, professedly used for the sake of their hydrogen, but always for the other half of the salt, the acidulous side. And it is not for their basylous radical that these hydrogen salts are now commended to notice,* but in order to study, under the most favora- ble circumstances, these acidulous groupings which have continually presented themselves in operations on salts, but which were for the time of secondary importance. They may now be treated as the pri- mary object of attention ; and there is no better way of doing so than in operating on their compounds with hydrogen, the relatively infe- rior medicinal importance of which element, as compared with potas- sium, iron, and other basylous radicals, will serve to give the desired prominence to the acidulous radicals in question. Common Acids. — These salts of hydrogen are the ordinary, sharp, sour bodies termed acids (from the Latin root acies, an edge). The following Table includes the formulae and usual names of the most important ; others will be noticed subsequently. A few of those men- tioned are unstable or somewhat rare ; in such cases a common me- tallic salt containing the acidulous radical may be used for reactions. * It must not be forgotten that the commonest salt of any radical whatsoever is a salt of hydrogen, the oxide of hydrogen (H2O), or hydrate of hydrogen (HHO), water. In the reactions already per- formed, the value of this compound has been constantly recognized, both for its hydrogen and for its oxygen, but most of all as the vehicle or medium by which nearly all other atoms are enabled to come into that contact with each other without which their existence would be almost useless ; for some atoms are like some animals, out of water they are as inactive as fishes. It is true that both fishes and salts have usually to be removed from water to be utilized by man ; but before they can be assimilated, either as food or as medicine, they must ngain seek the agency of water — become dissolved. 236 THE ACIDULOUS RADICALS, HCl hydrochloric acid. HBr hydrobromic acid. HI hydriodic acid. HCN (HCy) hydrocyanic acid. HNO., nitric acid. HClOg chloric acid. acetic acid.* H^S hydrosulphuric acid.f H^SO. sulphurous acid. H^SO; sulphuric acid. H.,CO, ? carbonic acid. oxalic acid. H,C,H,0, tartaric acid. HsC.H.O, citric acid. H.,PO, phosphoric acid. H3BO3 boracic acid. The old names are here retained for these acids, but, in studying their chemistry and chemical relations to other salts, they are use- fully spoken of by such more purely chemical names as (for hydro- chloric acid) chloride of hydrogen, (for nitric acid) nitrate of hydro- gen, and so on — sulphate of hydrogen, tartrate of hydrogen, phos- phate of hydrogen. A prominent point of difference will at once be noticed between the basylous radicals met with up to the present time and the acidu- lous groupings included in the above tabular list. The former are nearly all elements, ammonium only being a compound; the latter are mostly compounds, chlorine, bromine, iodine, and sulphur being the only elements. This difference will not, however, be so apparent when the chemistry of alcohols, ethers, and such bodies has been mas- tered, for they are all salts of compound basylous radicals. Rarer Acids . — The above acids contain the only acidulous group- ings that commonly present themselves in analysis, or in pharma- ceutical operations. There are, however, several other acids (such as hypochlorous, nitrous, hypophosphorous, valerianic, benzoic, gallic, tannic, uric, hyposulphurous, hydroferrocyanic, hydroferridcyanic, and lactic) with which it is desirable to be more or less familiar ; reactions concerning these will therefore be described. Arsenious, arsenic, stannic, manganic, and chromic acids have already been * The hydrogen on the acidulous side must not be confounded with the basylous hydrogen in all these hydrogen salts or acids; the two pe^rform entirely different functions. Hydrogen in the acidulous por- tion is like the hydrogen in the basylous radical ammonium, it has combined with other atoms, to form a group wliich plays more or less the part of an elementary radical, and to which a single symbol is not unfrequently applied (Am ; Cy, A, 0, T, C, etc.). Cobalt, chromium, iron, platinum, etc., resemble hydrogen in this respect in often uniting with other atoms to form definite acidulous radicals, in which the usual basylous character of the metals has for the time disappeared. In hydrides (p. 105) hydrogen itself is an acidulous radical. f Synonyms : sulphydric acid and sulphuretted hydrogen. THE ACIDULOUS RADICALS. 237 treated of in connection with the metals they contain ; in practical analysis they always become sufficiently altered to come out among the metals. Quantivalence . — A glance at the foregoing Table is sufficient to show the quantivalence of the acidulous radicals. The first seven are clearly univalent; then follow six bivalent, leaving three tri- valent. These all combine with equivalent amounts of basylous radicals to form various salts ; hence they may be termed monobasylous, di- basylous and tribasylous radicals. The acids themselves were for- merly spoken of as monobasic, dibasic, and tribasic respectively, or monobasic and polybasic, in reference to the amount of hase (hy- drates or oxides) they could decompose ; but the terms are no longer definite, and hence but little used in mineral chemistry. Antidotes . — The antidotes in cases of poisoning by the strong acids will obviously be non-corrosive alkaline substances, as soap and water, magnesia, common washing “ soda,’’ or other carbonates. Yinegar, lemon-juice, and weak or non-corrosive acid, would be the appropriate antidotes to caustic alkalies. Analysis . — The practical study of the acidulous side of salts will occupy far less time than the basylous. Salts will then be briefly examined as a whole. One Word of Caution . — It is only for convenience in the division of chemistry for systematic study that salts maybe considered to contain basylous and acidulous radicals, or separate sides, so to speak ; for we possess no absolute knowledge of the internal arrangement of the atoms (admitting that there are such things) in the molecule of a salt. We only know that certain groups of atoms may be trans- ferred from compound to compound in mass (that is, without apparent decomposition) ; hence the assumption that these groups are radicals. A salt is probably, however, a whole, having no such ^ides as those mentioned. QUESTIONS AND EXERCISES. 410. Mention the basylous radical of acids. 411. Give illustrations of univalent, bivalent, and trivalent acidu- lous radicals, or monobasylous, dibasylous, and tribasylous radicals. 412. What is the difference between an elementary and a com- pound acidulous radical ? ^ 413. Name the grounds on which salts may be assumed to contain basylous and acidulous radicals. 238 SALTS OF ACIDULOUS RADICALS. HYDROCHLOmC ACID AND OTHER CHLORIDES. Formula of hydrochloric acid HCl. Molecular weight* 36.5. The acidulous radical of hydrochloric acid and of other chlorides is the element chlorine (Cl). It occurs in nature chiefly as chloride of sodium (NaCl), either solid, under the name of rock-salt, mines of which are not unfrequently met with, or in solution in the water of all seas. Common table-salt is more or less pure chloride of sodium in minute crystals. ' Chlorine, like hydrogen, is univalent (Cl') ; its atomic weight is 35.5. Its molecule is symbolized thus, CI 2 , chloride of chlorine. Reactions. Hydrochloric Acid. First Synthetical Reaction , — To a few fragments of chlo- ride of sodium in a test-tube or small flask add about an equal weight of sulphuric acid ; colorless and invisible gaseous h^^drochloric acid is evolved, a sulphate of sodium remaining. Adapt to the mouth of the vessel, by a per- forated cork, a piece of glass tubing bent to a right angle, heat the mixture, and convey the gas into a small bottle containing a little water; solution of hydrochloric acid results. NaCl + H,SO, HCl + NaHSO, Chloride of Sulphuric Hydrochloric Acid sulphate sodium. acid. acid. of sodium. Hydrochloric Acid. — I'he product of this operation is the nearly colorless and very sour liquor commonly termed hydrochloric acid. When of certain given strengths (estimated by volumetric analysis) it forms Acidum Hydrochloricum, B. P. and Acidum Muriaticum, U. S. P., and Acidum Hydrochloricum Dilidum, B. P. (and U.S. P., specific gr. 1.038). The former has a specific gravity of 1. 16 (1. 1578), and contains 31.8 per cent, of real acid, the latter specific gravity 1.052, with 10.58 per cent, of real acid, and is made by diluting 8 fluid parts of the strong acid with water until the mixture measures 26^ fluid parts. The above process is that of the Pharmacopoeias — larger vessels being employed, and the gas being freed from any trace of sulphuric acid by washing. Other chlorides yield hydro- chloric acid when heated with sulphuric acid; but chloride of sodium is always used because cheap and common. Common yellow hydrochloric acid is a by-product in the manufac- ture of carbonate of sodium from common salt, a process in which the chloride of sodium is first converted into sulphate, hydrochloric acid being liberated. This impure acid is liable to contain iron, arsenic, * The weight of a molecule is the sum of the weights of its atoms. CHLORIDES, 239 fixed salts, sulphuric acid, sulphurous acid, nitrous compounds, and chlorine. The official (B. P.) process as follows : — ‘‘ Take of chloride of sodium, dried, 48 ounces, sulphuric acid 44 fluidounces; water 36 fluidounces, distilled water 50 fluidounces; pour the sulphuric acid slowly into thirty-two ounces of the water, and, when the mixture has cooled, add it to the chloride of sodium pre- viously introduced into a flask having the capacity of at least one gallon. Connect the flask by corks and a bent glass tube with a three-necked wash-bottle, furnished with a safety tube, and contain- ing the remaining four ounces of the water; then, applying heat to the flask, conduct the disengaged gas through the wash-bottle into a second bottle containing the distilled water, by means of a bent tube dipping about half an inch below the surface, and let the process be continued until the product measures sixty-six ounces, or the liquid has acquired a specific gravity of 1.16. The bottle containing the distilled water must be kept cool during the whole operation.” Invisible gaseous hydrochloric acid forms visible grayish-white fumes on coming into contact with air. This is due to combination with the moisture of the air. The intense greediness of hydrochloric gas and water for each other is strikingly demonstrated on opening a test-tube full of the gas under water ; the latter rushes into and in- stantly fills the tube. If the water is tinged with blue litmus, the acid character of the gas is prettily shown at the same time. The test-tube, which should be perfectly dry, may be filled from the de- livery-tube direct; for the gas is somewhat heavier than, and there- fore readily displaces, air. The mouth may be closed by the thumb of the operator. Note . — The process, as described in the British Pharmacopoeia, includes the use of as much sulphuric acid as is theoretically neces- sary for the production of acid sulphate of sodium (NaHSO^) which remains in the generating vessel. A hot solution of' this residue carefully neutralized by carbonate of sodium, filtered and set aside, yields normal sulphate {Sodii Sulphas, U. S. P.), in the form of transparent oblique efflorescent prisms (Na^SO^, IOH 2 O). 2 NaHS 04 + Na^COg = 2Na2SO, + H^O -f CO^ Acid sulphate Carbonate of Sulphate of Water. Carbonic of sodium. sodium. sodium. acid gas. Chlorine. Second Synthetical Reaction . — To some drops of hydro- chloric acid (that is, the common aqueous solution of the gas) add a few grains of black oxide of manganese, and warm the mixture ; chlorine., the acidulous radical of all chlorides, is evolvecl, and ma}^ be recognized by its peculiar odor, or irritating effect on the nose and air-passages. 4HC1 -f MnO, = C\, -f + MnCl^ 240 SALTS OP ACIDULOUS RADICALS. Chlorine-icater. — This is the process of the Pharmacopoeias for the production of chlorine-water [Liquor Clilori, B. P., Aqua Clilorinii, U. S. P.), the gas being first washed and then passed into water. Six fluidounces of hydrochloric acid diluted with two ounces of water, and the gas passed through a wash-bottle containing about two ounces of water, yield enough chlorine to produce about a pint and a half of chlorine-water. On the small scale, less than half the acid is utilized through incomplete decomposition and incomplete absorption of the chlorine gas. Chlorine slowly decomposes water with production of hydrochloric acid and oxygen gas ; it is best preserved in a green- glass well-stoppered bottle in a cool and dark place. At common temperatures (60^ F.), if fresh and thoroughly saturated, chlorine- water contains more than twice (2.3) its bulk of chlorine, or less than 1 per cent, (about 0.75) by weight Note. — To obtain the chlorine from other chlorides, sulphuric acid, as well as black oxide of manganese, must be added. Hydrochloric acid is first formed. The action described in the above equation then goes on, except that half instead of the whole of the oxygen of the black oxide is available for the removal of the hydrogen from the chlorine of the hydrochloric acid, the other half being taken up by the hydrogen of the sulphuric acid. Thus, supposing common salt to be the chloride used, the following equations may represent the supposed steps of the process : — 2NaCl + H^SO, = Na.,SO, + 2HC1, MnO, + H^SO, = MnSO^ + H.,0 + 0 ; then the 2HC1 +0 = H^O + Cl^ or the whole may be included in one equation : — 2NaCl + MnO^ + 2H,SO, = Na,SO, + MnSO, + 2H,0 + Cl^. This reaction may have occasional analytical interest, a very small quantity of combined chlorine being recognized by its means. But the following test is nearly always applicable for the detection of this element, and leaves nothing to be desired in point of delicacy. Analytical Reaction ( Test). To a drop of h^^drocbloric acid, or to a dilute solution of any other chloride, add solution of nitrate of silver ; a white curdy precipitate falls. Pour off most of the super- natant liquid, add nitric acid and boil ; the precipitate does not dissolve. Pour off the acid, and add ammonia; the precipitate quickly dissolves. Neutralize the solution by an acid, chloride of silver is once more precipitated. The formation of this white precipitate, its appearance, insolubility in boiling nitric acid, solubility in ammonia, and reprecipitation by an acid, form abundant evidence of the presence of chlorine. Its occurrence as a chloride of a metal is determined by testing for the metal with the appropriate reagent ; its occurrence as hydrochloric acid is considered to be indicated by the odor, if strong, and the sour BROMIDES. 241 taste, if weak, of the liquid, and the action of the liquid on blue litmus paper, which, like other acids, it reddens. If hydrochloric acid be present in excessive quantity it will, in addition to the above reac- tions, give rise to strong effervescence on the addition of a carbonate, a chloride being formed. The chlorine in insoluble chlorides, such as calomel, ‘‘white precipitate,” etc., may be detected by boiling with caustic potash, filtering, acidulating the filtrate by nitric acid, and then adding the nitrate of silver. Antidotes. — In cases of poisoning by strong hydrochloric acid, solution of carbonate of sodium (common washing-soda) or a mixture of magnesia and water may be administered as an antidote. QUESTIONS AND EXERCISES. 414. A specimen of official Hydrochloric Acid contains 31.8 per cent, by weight of gas, and its specific gravity is 1.16 ; work out a sum showing what volume of it will be required, theoretically, to mix with black oxide of manganese for the production of one gallon of chlorine-water, one fluidounce of which contains 2.66 grains of chlo- rine. Ans. fluidounces, nearly. 415. Why does hydrochloric acid gas give visible fumes on coming into contact with air ? 416. How much chloride of sodium will be required to furnish one pound of chlorine ? 417. Give the analytical reactions of chlorides. 418. What antidotes may be administered in cases of poisoning by hydrochloric acid ? HYDROBROMIC ACID AND OTHER BROMIDES. Formula of Hydrobromic Acid HBr. Molecular weight 81. Bromine. Source^ Preparation, and Properties . — The acidulous radical of hydrobromic acid and other bromides is the element bro- mine, Br [Bromum, B. P., Brominium, U. S. P.). It occurs in nature chiefly as bromide of magnesium (MgBr 2 ) in sea-water and certain saline springs. It may be liberated from its compounds by the pro- cess for chlorine from chlorides — that is, by heating with black oxide of manganese and sulphuric acid (see previous page). It is a dark- red volatile liquid, emitting an odor more irritating, if possible, than chlorine — of specific gravity 2.966, boiling-point 145.40. Quantivalence. — The atom of bromine, like that of chlorine, is univalent (Br') ; its atomic weight is 80. Free bromine has the molecular formula Br^, bromide of bromine. Hydrobromic Acid. — The bromide of hydrogen, hydrobromic acid, is made by decomposing bromide of phosphorus by water — PBr.-h 4H20 = 5HBr+H3P0,. Bromide of Potassium (KBr) is occasionally employed in phar- 21 242 SALTS OF ACIDULOUS RADICALS. macy, and is the salt, therefore, which may be used in studying the reactions of this acidulous radical. The official method of making the salt has been alluded to under the salts of potassium (page 63). Other bromides are seldom used ; they may be prepared in the same way as, and closely resemble, the corresponding chlorides or iodides. Bromide of Ammonium (AmBr) [Ammonii Bromidum, B. P. and U. S. P.) is prepared by agitating iron wire with a solution of bromine until the odor of bromine can be no longer perceived, adding solution of ammonia, filtering and evaporating the filtrate to dryness. It forms a white, granular salt which becomes slightly yellow on ex- posure to air, is readily soluble in water, less so in spirit, and, when heated, sublimes. Solution of Bromine, B. P., 10 minims in 5 ounces, is an aqueous solution, bromine being slightly soluble in water. Hypohromites, Bromates, Ferhromates, analogous to hypochlo- rites, chlorates, and perchlorates, are producible. Analytical Reactions (Tests). First Analytical Reaction, — To a few drops of solution of a bromide (KBr, or NH^Br) add solution of nitrate of silver ; a yellowish-white precipitate of bromide of silver (AgBr) falls. Treat the precipitate successively with nitric acid and ammonia, as described for the chloride of silver ; it is only sparingly dissolved by the ammonia. Second Analytical Reaction, — To solution of a bromide add a drop or two of chlorine-water, or a bubble or two of chlorine gas ; then add a few drops of chloroform or ether, shake the mixture, and set the test-tube aside; the chlo- rine, from the greater strength of its affinities, liberates the bromine, which is dissolved by the chloroform or ether, the solution falling to the bottom of the tube in the case of the heavy chloroform, or rising to the top in the case of the light ether. Either solution has a distinct yellow, or red- dish-yellow or red color, according to the amount of bromine present. Notes. — This reaction serves for the isolation of bromine wheli mixed with many other substances. Excess of chlorine must be avoided, as colorless chloride of bromine is then formed. Iodides give a somewhat similar result ; the absence of iodine must therefore^ be insured by a process given in the next section. The above solu-^ tion in chloroform or ether may be removed from the tube by draw- ing up into pipette (small pipe, a narrow glass tube, usually having a bulb or expanded portion in the centre) the bromide fixed by the addition of a drop of solution of potash or soda, the chloroform or ether evaporated off, and the residue tested as described in the next reaction. IODIDES. 243 The above operation is frequently employed for synthetical pur- poses. Third Analytical Beaction. — Liberate bromine from a bromide by the cautious addition of chlorine or chlorine- water, then add a few drops of cold decoction of starch ; a yellow combination of bromine and starch, commonly termed ‘‘ bromide of starch.’^ is formed. Decoction of starch is made by rubbing down two or three grains of starch with some drops of cold water, then adding much more water and boiling the mixture. “The above reaction may he varied by liberating the bro- mine by a little black oxide of manganese and a drop of sulphuric acid, the upper part of the inside of the test-tube being smeared over with some thick decoction of starch or thin starch-paste. HYDRIODIC ACID AND OTHER IODIDES. Formula of Hydriodic Acid HI. Molecular weight 128. Source. — The acidulous radical of hydriodic acid and other iodides is the element iodine (I). It occurs in nature chiefly as iodide of sodium and of magnesium in sea- water. Seaweeds, sponges, and other marine organisms, which derive much of their nourishment from sea- water, store up iodides in their tissues, and it is from the ashes of these that supplies of iodine [lodum, B. P., lodinium, U. S. P.) are obtained. Process. — The seaweed ash or kelp is treated with water, insoluble matter thrown" away, and the decanted liquid evaporated and set aside to allow of the deposition of most of the sulphates, carbonates, and chlorides of sodium and potassium. The residual liquor is treated with excess of sulphuric acid, w^hich causes evolution of carbonic and sulphurous or sulphuretted gases, deposition of sulphur and more sulphate of sodium, and formation of hydriodic acid. To the de- canted liquid is added black oxide of manganese, and the mixture is then slowly distilled ; the iodine sublimes, and is afterwards purified by re-sublimation. 2HI -b MnO^ + H^SO, = MnSO, -f 2}I,0 + I^. 21ie analogy of chlorine^ bromine, and iodine is well indicated by the fact that each is obtained from its compounds by the same reaction. Iodine is liberated from any iodide as bromine from bro- Vjmides, or chlorine from chlorides — namely, by the action of black oxide of manganese and sulphuric acid. Properties. — Iodine is a crystalline purplish-black substance ; its vapor, readily seen on heating a fragment in a test-tube, is dark violet. Its vapors are irritating to the lungs; but a trace may be inhaled with safety ( Vapor lodi, B. P.). It melts at 239°, boils at " about 392^, and is entirely volatilized, the first portions containing 214 SALTS OF ACIDULOUS RADICALS. any cyanide of iodine that may be present. The latter body occurs in slender colorless prisms, emitting a pungent odor. Quantivalence — The atom of iodine, like those of bromine and chlorine is univalent* (!') ; its atomic weight is 127, its molecular formula I 2 . The Iodide of Hydrogen, or Hydriodic Acid, is a heavy, color- less gas. Its solution in water is made by passing sulphuretted hy- drogen through water in which iodine is suspended. 2 II 2 S + 2 I 2 = S 2 4- 4HI. Iodide of potassium (KI) is largely used in medicine, and hence is the most convenient iodide on which to experiment in studying.the reactions of this acidulous radical. Solid iodine itself might l3e taken for the purpose ; but its use and action in that* state have already been alluded to in describing the iodides of potossium, cadmium, and mercury ; its analytical reactions in the combined condition are those which may now occupy attention. Solution of Iodine. — Iodine is slightly soluble in water (iodine- water), and readily soluble in an aqueous solution of iodide of g^as- sinm. Twenty grains of iodine and 30 of iodide of potassinmT^is- solved in I ounce of distilled water, form Liquor lodi, B. P. ; Liquor lodinii Compositus, U. S. P., is of the same character and about tl^e same strength ; 32 grains of iodine and 32 of iodide of potassium, rubbed with I fluidrachm of proof spirit, and 2 ounces of lard gradu- ally mixed in, form Unguentum lodi, B. P. Unguentum lodinii Compositum, U. S. P., and Unguentum lodinii, U. S. P., are simi- lar preparations. It is more soluble in spirit ( Tinctura lodinii, U. S. P.), or in a spirituous solution of iodide of potassium [Tinctura lodi, B. P., Tinctura lodinii Gomposita, U. S. P.). It combines with sulphur, forming an unstable grayish-black solid iodide (S.^I^), having a radiated crystalline structure [Sulph uris lodidum, B. P. and U. S. P., and Unguentum Sulphuris lodi di). If 100 grains be thoroughly boiled with w^ater the iodine will pass off' in vapor, and about 20 grains of sulphur remain. — B. P. and U.S.P. Analytical Reactions ( Tests). First Analytical Reaction. — To a few drops of an aque- ous solution of an iodide {e. g. KI) add solution of nitrate of silver ; a yellowish-white precipitate of iodide of silver (Agl) falls. Pour away the supernatant liquid and treat the precipitate with nitric acid, it is not dissolved; pour aw^ay the acid and then add ammonia, it is only sparingly dissolved. * There is a compound of iodine having the formula ICI3. Iodine would therefore seem to be a trivalent element (B") ; and bromine and fluorine, from their close chemical analogy with iodine, would necessa- rily be regarded as trivalent also. From this aspect the position of chlorine would be anomalous. IODIDES. 245 This reaction is useful in separating iodine from most other acidu- lous radicals, but does not distinguish iodine from bromine. Ammonia, it will be remembered, dissolves chloride of silver readily ; hence the presence of chloride of potassium in bromide or iodide may be detected by dissolving in water, adding excess of nitrate of silver, collecting the precipitate, washing, digesting in ammonia, filtering and adding excess of nitric acid to the filtrate ; a white curdy pre- cipitate indicates a chloride (of potassium). Second Analytical Reaction , — Liberate iodine from an iodide by the cautious addition of chlorine, then add cold decoction of starch ; a deep-blue combination of iodine and starch, commonly termed “ iodide of starch,’’ is formed. Starch is highly sensitive to the action of iodine; this reaction is consequently very delicate and characteristic. Excess of chlorine must be avoided, or colorless chloride of iodine will be produced. Nitrous acid, or a nitrite acidulated wdth sulphuric acid, may be used iiistea^of chlorine. The reaction is not observed in hot liquids. In testing bromine for iodine the bromine must be if^rly all re- moved by solution of sulphurous acid before the decoction of starch is added. Ozone (O3). — Papers soaked in mucilage of starch containing iodide of potassium, form a test for free chlorine and nitrous acid, and are also employed by meteorologists to detect an allotropic and energetic form oxygen termed by Schonbein ozone (from o^a;, ozo^ to smell). Thi^ 'substance liberates iodine from iodide of potassium (with forma- tion of iodide of starch), and is supposed to occur normally in the atmosphere, the salubrity or insalubrity of which is said to be de- pendent to some extent on the presence or absence of ozone. The possible occurrence of nitrous or chlorinoid gases in the air, however, renders the test untrustworthy. Houzeau proposes to test for ozone by exposing litmus paper of a neutral tint soaked in a dilute solution of iodide of potassium ; the potash set free by action of the ozone turns the paper blue. The same paper without iodide would indicate the extent to which the effect might be due to ammonia vapor. Ozone, or rather ozonized air, is produced artificially in large quantities on passing air through a box (Beane’s Ozone-generator) highly charged with electricity. Small quantities may be obtained by exposing in a loosely closed bottle a stick of phosphorus partially covered by water. It is a powerful bleaching, disinfecting, and general oxidizing agent ; insoluble in water, soluble in oils of turpentine, cinnamon, and some other liquids. From experiments that have been made by Soret on the specific gravity of ozone, its molecular formula would seem to be O 3 , that of ordinary oxygen being O 2 , Its smell is pecu- liar.v (See p. 211, also “Blood.”) Third Analytical Reaction To a neutral aqueous solu- tion of an iodide add a solution containing one part of sulphate of copper to two parts of green sulphate of iron ; a dirtv-white precipitate of cuprous iodide (Cu^I^) falls. 21 * 246 SALTS OF ACIDULOUS RADICALS. 2KI + 2CiiSO, + 2FeSO, = CuJ, + K,SO, + F^SSO, Separation of Chlorides, Bromides, and Iodides. — Chlorides and bromides are not affected in this way ; the reaction is useful, there- fore, in removing iodine from a solution in which chlorides and bromides have to be sought. The total removal of iodine by this process is insured by supplementing the addition of the cupric and ferrous sulphate by a few drops of ammonia, any acid which might be keeping cuprous iodide in solution being thereby neutralized, ferric or ferrous hydrate, precipitated at the same time, not affecting* the reaction. (Chloride of the rare metal palladium performs a similar useful office in removing iodinCj but not bromine or chlorine, from solutions. Chlorides may be separated from bromides by taking advantage of the ready solubility of chloride of silver, and almost complete insolubility of bromide of silver in ammonia. Fourth Analytical Reaction . — Iodides have been shown to be useful in testing for mercuric salts (see the Mercuiy reactions, p. 112); a mercuric salt (corrosive sublimate, for example) may therefore be used in testing for iodides, a scarlet precipitate of mercuric iodide (Hgl 2 ) being pro- duced. This reaction may be employed where large quantities of an iodide are present ; but its usefulness in analysis is much impaired by the fact that the precipitate is soluble in excess of the dissolved iodide, or in excess of the mercuric reagent. Its color and insolubility in water distinguish it from mercuric chloride, bromide, and cyanide, which are white soluble salts. Fifth Analytical Reaction . — Iodides have also (see the Lead reactions, p. 190) been shown to be useful in testing for lead salts ; similarlj^ a lead salt (acetate, for example) maybe used in testing for iodides, a yellow precipitate of iodide of lead (Pbl 2 ) soluble in hot water and crystallizing in yellow scales on cooling, being produced. Chloride, bromide, and cyanide of lead are white; hence the above reaction may occasionally be useful in distinguishing iodine from the allied radicals. But iodide of lead is slightly soluble in cold water; hence small quantities of iodide cannot be detected by this reaction. (For lodates see p. 263.) Analogies between Chlorine, Bromine, Iodine, and their Com- ponifids. — These elements form a natural group or family, each dis- tinct from the other yet closely related. Moreover their dissimilari- ties are so curiously gradational as to irresistibly suggest the idea that some day we may find the differences between these bodies to be in degree rather than in kind. Thus chlorine is a gas and iodine a solid, while bromine occupies the intermediate condition. The atomic weight of bromine is nearly midway between those of chlorine and iodine. The same may be said of the weight of equal volumes CYANIDES. 24T of each in the gaseous state. The specific gravity of fluid chlorine is 1.33, of iodine 4.95, while bromine is nearly 3. Liquid chlorine is transparent, iodine opaque, bromine intermediate. The crystalline forms of the chloride, bromide, and iodide of a metal are commonly identical. One volume of either element in the gaseous state com- bines with an equal volume of hydrogen (at the same temperature) to form two volumes of a gaseous acid, very soluble in water (hydro- chloric acid, hydrobromic acid, hydriodic acid). Many other analo- gies. are traceable. QUESTIONS AND EXERCISES. 419. State the method by which Bromine is obtained from its natural compounds. 420. Mention the properties of bromine. 421. How may the Bromides of Potassium and Ammonium be made ? 422. By what reagents may bromides be distinguished from chlorides ? 423. Whence is iodine obtained? 424. By what process is iodine isolated ? 425. State the properties of iodine. 426. What is the nature of Iodide of Sulphur? 427. Give the analytical reactions of iodides. 428. Which three substances may be detected by a mixture of iodide of potassium and mucilage of starch ? 429. Describe a method by which iodides may be removed from a solution containing chlorides and bromides. HYDROCYANIC ACID AND OTHER CYANIDES. Formula of Hydrocyanic Acid HNO or HCy. Molecular weight 27. History of Cyanogen . — The acidulous radical of hydrocyanic acid and other cyanides is a compound body, cyanogen (Cy). It is so named from xvavo^ kuanos, blue, and ysvvdco, gennao, I generate, in allusion to its prominent chemical character of forming, with iron, the different varieties of Prussian blue. It was from Prussian blue that Scheele, in 1782, first obtained what we now, from our knowl- edge of its composition, term hydrocyanic acid, but which he called Prussic acid. Cyanogen was isolated by Gay-Lussac in 1814, and was the first compound radical distinctly proved to exist. Sources . — Cyanogen does not occur in nature, and is only formed from its elements under certain circumstances. It is found in small quantities among the gases of iron-furnaces, and is produced to a slight extent in distilling coals for gas. In the form of ferrocyanide of potassium it is obtained abundantly by heating animal refuse 248 SALTS OF ACIDULOUS RADICALS. containing nitrogen, such as the scrapings of horns, hoofs, and hides (5 parts)" with carbonate of potassium (2 parts) and waste iron (filings, etc.) in a covered iron pot. The residual mass is boiled with water, the mixture filtered, and the filtrate evaporated and set aside for crystals to form. The cyanogen, produced from the carbon and nitrogen of the animal matter, unites with the potassium and after- wards, on boiling with water, with iron to form what is known as the yellow prussiate of potash [Potassoe Prussias Flava, B. P.), or fer- rocyanide of potassium (K'4Fe"Cy'g, [Potassii Ferrocyanidum, U. S. P.), a compound occurring in four-sided tabular yellow crystals. It contains the elements of cyanogen, yet it is not a cyanide, for it is not poisonous, and is otherwise different from cyanides ; it will be further noticed subsequently. From this salt all cyanides are di- rectly or indirectly prepared. Cyanide of 'potassium (KCy) [Potassii Cyanidum^ U. S. P.), wdiich is the most common, is procured by fusing ferrocyanide of potassium in a crucible; carbonic acid gas (OO.J is evolved, iron (Fe) is set free, and cyanate of potassium (KCyO), a body that will be subsequently noticed, is formed at the same time ; — 2K,FeCy6 + 2K,CO, = lOKCy + 2KCyO + Fe2 + 2CO2. Double cyanides exist, such as the cyanide of sodium and silver (NaCy.AgCy), formed in the process (subsequently described), of quantitatively determining the amount of hydrocyanic acid in a liquid by a standard solution of nitrate of silver : these compounds have, more or less, the properties of their constituents. But other cyanogen compounds, not double cyanides, occur in which the cyano- gen is so intimately united with a metal as to form a distinct radical : such are ferrocyanides and ferridcyanides — salts which will be noticed in due course. Cyanogen, like chlorine, bromine, and iodine, is univalent (Cy'). It may be isolated by simply heating mercuric cyanide (HgCy2) or cyanide of silver ( AgCy). It is a colorless gas, burning, when ignited, with a beautiful peach-blossom-colored flame. Mercuric cyanide is produced in crystals on dissolving 1 part of ferrocyanide of potassium in 15 parts of boiling water, adding 2 parts of mercuric sulphate, keeping the whole hot for ten or fifteen minutes, and then filtering and setting aside to cool. In addition to mercuric cyanide (HgCy2), mercury (Hg), ferric sulphate (Fe23S04) and sul- phate of potassium (K2SO4), are formed. Any excess of ferrocyanide also gives Prussian blue by reaction with ferric sulphate. It [Hy- drargyri Cyanidum, U. S. P.) may also be made by dissolving red oxide of mercury in diluted hydrocyanic acid. A small flame of cyanogen may be obtained on heating a few crystals of mercuric cyanide in a short piece of glass tubing closed at one end, and apply- ing a light to the other end as soon as evolution of gas commences. CYANIDES. 249 Eeactions. Diluted Hydrocyanic Acid. Synthetical Reaction . — Dissolve 2 or 3 grains of ferrocj^a- nide of potassium in 5 or 6 times its weight of water in a test-tube, add a few drops of sulphuric acid and boil the mixture, conveying the evolved gas by a bent glass tube (adapted to the test-tube by a cork) into another test-tube containing a little water; the product is a dilute solution of h3Tlrocyanic acid. Made by this process in large quan- tities of a certain definite strength (2 per cent.), this solu- tion is the Acidum HydrocyoMicum Dilutum.^ B. P. and U. S. P. A colorless liquid of a peculiar odor. Specific gravity 0 . 997 .'' 2K,FeCye -f 6H,SO, = FeK^Fe'^Cyg + 6KHSO, -f 6HCy. The details of the official process are as follows : Dissolve 2| ounces of ferrocyanide of potassium in 10 ounces of water, add 1 fluidounce of sulphuric acid previously diluted with four ounces of water and cooled. Put the solution into a flask or other suitable apparatus of glass or earthenware, to which are attached a condenser and a receiver arranged for distillation ; and having put 8 ounces of distilled water into the receiver, and provided efficient means for keeping the condenser and receiver cold, apply heat to the flask, until, by slow distillation, the liquid in the receiver is increased to 17 fluidounces. Add to this 3 ounces of distilled water, or as much as may be sufficient to bring the acid to the required strength, so that 100 grains (or 110 minims) of itj precipitated with a solution of nitrate of silver {vide paragraphs on quantitative analysis) shall yield 10 grains of dry cyanide of silver. The residue of this reaction is acid sulphate of potassium (KHSO4), which remains in solution, and ferrocyanide of potassium and iron (Fe"K.^FeCy6), insoluble powder sometimes termed Everitt’s yel- low salt, from the name of the chemist who first made out the nature of the reaction. The latter compound becomes bluish-green during the reaction, owing to absorption of oxygen. Diluted hydrocyanic acid may also be prepared by reaction of cyanide of silver and diluted hydrochloric acid. Pure anhydrous hydrocyanic acid is a colorless, highly volatile, intensely poisonous liquid, solidifying when cooled to a low tempera- ture. It may be made by passing sulphuretted hydrogen over mer- curic cyanide. The official solution of the acid is fairly stable, but is said to be rendered more so by the presence of a minute trace of sulphuric or hydrochloric acid. Note. — A few drops of diluted hydrocyanic acid so placed that its vapor may be inhaled, forms the Vapor A cidi Hydrocyaniciy B. P., or Inhalation of Hydrocyanic Acid. Hydrocyanic acid also occurs in cherry-laurel water and bitter- almond water [vide Index). 250 SALTS OP ACIDULOUS RADICALS. The methods of determining the strength of solutions of hydrocy- anic acid will be described in connection with volumetric and gravi- metric quantitative analysis. They are based on the formation of cyanide of silver and its solubility in solution of cyanide of potassium, as described in the next reaction. The hydrocyanic acid used in pharmacy is extremely liable to vari- ation in strength. It should frequently be tested volumetrically. Analytical Reactions ( Tests), First Analytical Reaction, — To a few drops of the hydro- C3’anic acid solution produced in the above reaction, or to any solution of a cyanide, add excess of solution of nitrate of silver; a white precipitate of cyanide of silver (AgCy) falls. When the precipitate lias subsided, pour away the supernatant liquid, and place half of the residue in another test-tube : to one portion add nitric acid, and notice that the precipitate does not dissolve ; to the other add ammo- nia, and observe that the precipitate is insoluble or only sparingly soluble. (Chloride of silver, which is also white, ^ is readily soluble in ammonia.) Cj^anide of silver dissolves in solutions of cyanides of alkali-metals, soluble double cyanides being formed (c. ^., KCy, AgCy). Solubility of precipitates in strong solutions of salts. — Cyanide of silver and many other precipitates insoluble in acids (similar re- marks apply to precipitates insoluble in alkalies) are often soluble in the strong saline liquids formed by the addition of acids and alka- lies to one another. Hence the precaution of adding the latter re- agents to separate portions of a precipitate, or of not adding the one until the other has been poured away. Cyanogen in an insoluble cyanide, such as cyanide of silver itself, is readily recognized on heating the substance in a short piece of glass tubing closed at one end like a test-tube and drawn out at the other end, so as to have but a small opening ; on applying a flame, the escaping cyanogen ignites and burns with a characteristic peach-blossom tint. Antidote. Second Analytical Reaction. — To a dilute solution of hydrocyanic acid, or a soluble c^^anide, add a few drops of solution of a ferrous salt and a drop or two of solution of a ferric salt (ferrous sulphate and ferric chloride are usually at hand) ; to the mixture add potash or soda (magnesia or carbonate of sodium), and then hydrochloric acid ; a pre- cipitate of Prussian blue remains. The decompositions may be traced in the following equations: — CYANIDES. 251 HCy + KHO = KCy + H^O 2KCy + FeSO, = FeCy, + K,SO, 4KCy 4- FeCv^ = K 4 FeCy(. or K,Fcy 3K,Fcy + 2Fefi\, = 12KC1 + Fe^Fcyg. The test depends on the conversion of the cyanogen into ferro- cyanogen by the iron of a ferrous salt, and the combination of the ferrocyanogen, so produced, with the iron of a ferric salt. Hence a mixture of green sulphate of iron, solution of perchlo- ride of iron, and either magnesia or carbonate of sodium, is the recognized antidote in cases of poisoning by hydrocyanic acid or cyanide of potassium. In such an alkaline mixture the poisonous cyanide, by reaction with ferrous hydrate, is at once converted into innocuous ferrocyanide of potassium or sodium ; should the mixture become acid, the ferric salt present reacts with the soluble ferrocyanide forming insoluble Prussian blue,' which is also inert. From the rapidity of the action of these poisons, however, there is seldom time to prepare an anti- dote. Emetics, the stomach-pump, the application of a stream of cold water to the spine, and the above antidote form the usual treat- ment. Third Analytical Reaction ^ — To solution of hydrocyanic acid add ammonia, and common yellow sulphydrate of ammonium, and evaporate the liquid nearly or quite to dryness in a small dish, occasionally adding ammonia till the excess of sulphydrate of ammonium is decomposed ; acidify the liquid with hydrochloric acid, and then add a drop of solution of a ferric salt; a blood-red solution of sulphocyanide of iron will be formed. This is a very delicate reaction. Some free’ sulphur in the yellow sulphydrate of ammonium unites with the alkaline cyanide and forms sulphocyanate (2AmCy + S 2 = 2AmCyS) ; the ammonia combines with excess of free sulphur and forms, among other salts, sulphydrate of ammonium, the whole of which is removed by the ebullition. If the liquid has not been evaporated far enough, sulphydrate of ammo- nium may still be present, and give black sulphide of iron on the addition of the ferric salt. Hydrocyanic acid in the blood . — According to Buchner the blood of animals poisoned by hydrocyanic acid, instead of coagulating as usual, remains liquid and of a clear cherry-red color for several days. In one case he obtained the reactions of the acid on diluting and dis- tilling the blood fifteen days after death, and applying the usual reagents to the distillate. Aqueous solution of peroxide of hydrogen (p. 88) changes such blood to a deep brown color. Schonbein's test for hydrocyanic acid is said to be extremely deli- cate. Filtering paper is soaked in a solution of 3 parts of guaiacum resin in 100 of alcohol. A strip of this paper is dipped in a solution of 1 part of sulphate of copper in 50 of water; a little of the suspected 252 SALTS OF ACIDULOUS RADICALS. solution is placed on tins paper and exposed to the air, when it im- mediately turns blue. Or the paper may be placed over the neck of an open bottle of medicine supposed to^contain hydrocyanic acid, or otherwise exposed to the vapor of the acid. QUESTIONS AND EXERCISES. 430. Write a paragraph on the history of cyanogen. 431. Mention the source of the cyanogen of all cyanides. 432. How is Ferrocyanide of Potassium prepared? 433. What is the formula of ferrocyanide of potassium ? 434. Is ferrocyanide of potassium poisonous ? 435. Write an equation expressive of the reaction which ensues when ferrocyanide and carbonate of potassium are brought together at a high temperature. 436. What are the properties of cyanogen ? How may it be ob- tained in a pure condition ? 437. How is mercuric cyanide prepared ? 438. How much real hydrocyanic acid is contained in the official liquid ? 439. Give details of the preparation of hydrocyanic acid, and an equation of the reaction. 440. State the proportion of water that must be added to an aque- ous solution containing 15 per cent, of hydrocyanic acid to reduce the strength to 2 per cent. — Ans. 6| to 1. 441. What are the characters of pure hydrocyanic acid? How may it be obtained ? 442. Enumerate the tests for cyanogen, giving equations. 443. Explain the action of the best antidote in cases of poisoning by hydrocyanic acid or cyanide of potassium. NITRIC ACID AND OTHER NITRATES. Formula of Nitric Acid HNO3. Molecular weight 63. Introduction . — The group of elements represented by the formula NO 3 is that characteristic of nitric acid and all other nitrates ; hence it is expedient to regard these elements as forming an acidulous radical, which may be termed the nitric radical. Like the hypo- thetical basylous radical ammonium (NH^), this supposed acidulous radical (NO.J has not been isolated. Possibly it is liberated when chlorine is brought into contact with nitrate of silver ; but if so, its decomposition into white crystalline nitric anhydride (N.^ 05 ) and oxygen ( 0 ) is too rapid to admit of its identification. Sources . — The nitrogen and oxygen of the air combine and ulti- mately form nitric acid whenever a current of electricity (as in the occurrence of lightning) passes. Nitrates are commonly met with in waters, soils, and the juices of plants. In the concentrated plant juices termed medicinal “Extracts,” small prismatic crystals of ni- NITRATES. 253 trate of potassium may occasionally be observed. (The cubical crystals often met with on extracts are chloride of potassium.) Ni- tric acid and other nitrates are obtained from nitrates of potassium and sodium, and these from the surface soil of tropical countries. Nitrate of potassium ov prismatic nitre (from the form of its crys- tals) is chiefly produced in and about the villages of India. The natives simply scrape the surface of waste grounds, mud heaps, banks, and other spots where a slight incrustation indicates the presence of appreciable quantities of nitre, mix the scrapings with wood-ashes (carbonate of potassium, to decompose the nitrate of calcium always present), digest the mixture in water, and evaporate the liquor. The impure product is purified by careful recrystalliza- tions, and is sent into commerce in the form of white crystalline masses or fragments of striated six-sided prisms. Besides its use in medicine [Potassii Nitras, U. S. P.), it is employed in very large quantities in the manufacture of gunpowder. Nitrate of Sodium (Sodii Nitras, U. S. P.) occurs in more distinct incrustations on the surface of the ground in Peru, Bolivia, and Chili, more especially in the district of Atacama ; it is distinguished as Chili saltpetre or (from the form of its crystals — obtuse rhomboids) cubic nitre, and is chiefly used as a manure and as a source of nitric acid, its tendency to absorb moisture unfitting it for use in gunpowder. In many parts of Europe nitrate of potassium is made artificially by exposing heaps of animal manure, refuse, ashes, and soil to the action of the air and the heat of the sun : in the course of a year or two the nitrogen of the animal matter becomes oxidized to nitrates, and the latter are removed by washing. Note. — The word nitric is from nitre, the English equivalent of the Greek vCifpov (nitron), a name applied to certain natural deposits of natron (carbonate of sodium), for which nitrate of potassium seems at first to have been mistaken. Saltpetre is simply sal petrce, salt of the rock, in allusion to the natural origin of nitrate of potas- sium. Sal 'prunella (from sal, a salt, and pruna, a live coal) is ni- trate of potassium melted over a fire and cast into cakes or bullets. The nitric radical is univalent (NO3'). Constitution of Salts. It is here necessary again to caution the reader against regarding salts as invariably possessing a known constitution, or supposing that they always possess two or more sides, or contain definite radicals. The erroneous conception which, of all others, is most likely to be imperceptibly formed is that of considering salts binary bodies. For, first the names of salts are necessarily binary. A student hears the names “ sulphate of iron,” “ sulphate of copper,” and simultaneously receives the impression that each salt has two sides, copper or iron occupying one and something indicated by the w^ords “ sulphate of” the other. Such words “ vitriol,” green or blue, or “ nitre,” would perhaps implant unitary ideas in the mind ; but it is simply impossi- ble to give such names to all salts as will convey the impression that each salt is a whole, and therefore unitary. The name “ sulphate of potash” produces binary impressions ; and the less incorrect name, 22 254 SALTS OP ACIDULOUS RADICALS. “ sulphate of potassium,” is in this respect no better. Secondly, it is impracticable to study salts as a whole. Teachers are unanimous in the opinion that students should first master the reactions charac- teristic of the metals in salts, and then the residues which, with those metals, make up the salts, or vice versa. It is not only im- practicable, but impossible, to study salts as a whole ; binary ideas concerning them are therefore almost inevitably imbibed. We come to regard a salt as a body which splits up in one direction only, look upon nitre, for instance, and all other nitrates, as containing N 0.^ and a metal, K ; whereas KNO3 maybe split up into KNO2 and 0; or into K^O, N2’ ^5 5 contain K2O and N2O5. These are the chief disadvantages attending the employment of the binary hypothesis in studying chemical compounds : if they be borne in mind, the hypothesis may be freely used without much danger of permanent mental bias. Thus in nitre let the group of elements (NO3) which, with potassium, makes up the whole salt be called the nitric radical, the name of the latter being directly derived from its hydro- gen salt. Similarly allow the acidulous residues of other salts of metals to be termed respectively the chloric, acetic, sulphurous, sul- phuric, carbonic, oxalic, tartaric, phosphoric, citric, boracic radicals. In short, these compound radicals should be regarded as groupings common to many salts, and which may usually be transferred without any apparent breaking or splitting ; at the same time we must be prepared to find that occasionally a salt divides in other directions. In this way perhaps erroneous impressions will gain least hold on the mind, and a way be left open for the easy entrance of new truths, should the real constitution of salts be discovered. Formerly salts (such as sulphate of magnesium) were regarded as containing (a) an oxide of a metal (MgO) and an anhydride (SO3), the latter being incorrectly called an acid (sulphuric acid), or ( 5 ) as containing two simple radicals [e. g. KI, NaCl, KCy, HgS) — the former being called oxyacid salts, or oxysalts, and the latter haloid salts (from als, seasalt, and eidos, likeness). Such distinc- tion is no longer maintained, the two classes being merged. This is an important educational gain on the side of simplicity ; for, whereas under the old system much time was necessarily expended before salts of a metal and salts of the oxide of that metal could be distin- guished (e. g. KI and Mg0,S03), now, all salts being regarded as salts of the metals themselves (e. g. KI and MgS04), tinction is necessary. Reactions. Nitric Acid. Synthetical Reaction , — To a fragment of nitrate of potas- sium or nitrate of sodium in a test-tube add a drop or two of sulphuric acid, and warm ; nitric acid (UNO,) is evolved in vapor. The fumes may be condensed by a bent tube fitted to the test-tube, not by a cork as for hydrochloric acid, because the nitric vapors w^ould strongly act on it, NITRATES. 255 blit by plaster of Paris, a paste of which sets hard on being set aside for a short time, and is unaffected by the acid. On a somewhat larger scale nitric acid may be prepared by heating, in a stoppered or plain retort, a mixture of equal weights of nitrate of potassium and sulphuric acid ; the acid distils over, and acid sulphate of potassium re- mains behind : — KNO3 + H,SO, = HNO3 + KHSO, Nitrate of Sulphuric Nitric Acid sulphate potassium. acid. acid. of potassium. Half the quantity of sulphuric acid may be taken ; but in that case neutral sulphate of potassium- (K2SO4) is produced, which, from its hard, slightly soluble character, is removed with difficulty from the retort. On the manufacturing scale the less proportion is used ; but instead of retorts iron cylinders are employed, from which the residual salt is removed by chisels. Moreover the cheaper sodium salt is the nitrate, from which manufacturers usually prepare nitric acid, seven parts of nitrate of sodium and four of sulphuric being employed. Note. — The acid sulphate of potassium is readily converted into neutral sulphate [Potassii Sulphas, U. S. P.) by dissolving in water, adding carbonate of potassium until effervescence ceases to occur, filtering, and setting aside to crystallize. Pure nitric acid (HNO^) is a colorless liquid, somewhat difficult of preparation ; its specific gravity is 1.52. The strongest acid met with in commerce has a sp. gr. of 1.5, and contains 93 per cent, of real nitric acid (HNO3); it fumes disagreeably, is unstable, and, except as an escharotic, is seldom used. The British and United States Pharmacopoeias contain two acids : Acidum Nitricum, pre- pared as above, of sp. gr. 1.42 (also in U. S. P.), and containing 70 per cent, of real acid HINO3); and another, Acidum Nitricum Dilutum, sp. gr. 1.101 (tJ. S. P. 1.068), containing nearly 17^ (17.44) per cent. Either of the stronger liquids, although containing Avater, is usually simply termed “ nitric acid.” The official nitric acid, of sp. gr. 1.42, is a definite hydrous acid (2HNO3, 3H2O) ; it distils at 250^ F. without change. If a weaker acid be heated it loses water, if a stronger acid be heated it loses nitric acid, until the density of 1.42 is reached. Aqua fortis is an old name for nitric acid [Aquafortis simplex, sp. gr. 1.22 to 1.25; Aqua fortis duplex, 1.36). The strength of a specimen of nitric acid is determined by volumetric analysis. Nitric anhydride (N^Og), sometimes but erroneously called anhydrous nitric acid, is a solid crystalline substance formed on passing dry chlorine over dry nitrate of silver. Aqua Regia. — Three fluidounces of nitric acid (B. P.), four of hydrochloric acid (B. P.), (3 to 5 by weight forms the Acidum Nitromuriaticum, U. S. P.), and twenty-five of water, give the Acidum Nitrohydrochloricum Dilutum of the British Pharmaco- poeia. The acids are ordered to be mixed twenty-four hours before dilution to insure mutual decomposition and full development of the chief active product, chlorine : — 256 SALTS OF ACIDULOUS RADICALS. 2HNO, -h 6HC1 = N2O2CI, + 4H2O + CI2 Nitric acid. Hydrochloric Chlorouitric Water. Chlorine, acid. gas. In the later stages of the reaction, the decomposition expressed in the following equation also probably occurs : — HNO3 + 3HC1 = NOCl + 2H2O + Cl, Nitric acid. Hydrochloric Chloronitrous Water. Chlorine, acid. gas. The same reaction occurs if the acids are mixed after dilution, but is not complete for a week or a fortnight (Tilden). The undiluted mixture of acids is known as aqua regia, so called from its property of dissolving gold, “ the king’’ of metals. Analytical Reactions ( Tests), First Analytical Reaction, — To a solution of any nitrate (e. g, KNO3) add sulphuric acid, and then copper turnings, and warm; colorless nitric oxide gas (NO) is evolved, which at once unites with the oxygen in tlie tube, giving red fumes of nitric peroxide or peroxide of nitrogen (NO,). 2KNO3 + 5ILSO,+ Cti3= 2 NO + 3CuS0,4-4H,0 + 2KHSO, ; 2NO+ 0,= 2N0,. Performed on a larger scale, in a vessel to which a delivery-tube is attached, this reaction becomes of synthetical interest, being the process for the preparation of nitric oxide gas for the purposes of chemical experiment. Small amounts of a nitrate may be overlooked by this test, tlie color of the red fumes not being very intense. Undiluted nitric acid poured on to copper turnings gives dense red vapors of nitrous acid (HNO,), nitrous anhydride (N,03), and nitric peroxide (NO,). Second Arialytical Reaction, — To a cold solution of the nitrate, even if very dilute, add three or four crystals of sulphate of iron, shake gently for a minute in order that some of the sulpliate may become dissolved, and then pour eight or ten drops of strong sulphuric acid down the side of the test-tube, so that it may form a layer at the bottom of the vessel ; a reddish-purple or black coloration will appear betw^een the acid and the supernatant liquid. This is a very delicate test for the presence of nitrates. I'he black color is due to a solution or, perhaps, combination of nitric oxide with a portion of the ferrous salt. The nitric oxide is liberated from the nitrate by the reducing action of the hydrogen of the sulphuric acid, the sulphuric radical of which is absorbed by the ferrous sul- phate, the latter salt becoming ferric sulphate. 2nN03+ 31T.,SO,+ 6FeSO, = 4H.,0 + 3(Fe.,3SOJ + 2NO. NITRATES. 257 The process of oxidation is one frequently employed in experi- mental chemistry ; and nitrates, from their richness in oxygen, but more especially because always at hand, are the oxidizers usually selected for the purpose. In the operation they generally split up in one way, namely, into oxide of their basylous radical, nitric oxide gas, and available oxygen. Thus hydrogen nitrate (nitric acid) yields oxide of hydrogen (water) and the other bodies mentioned, as shown in the following equation : — 4NHO3 = 2H2O + 4NO + 30.,. When nitrates, other than nitric acid, are used for the purpose of oxidation, a stronger acid, generally sulphuric, is commonly added in order that nitric acid may be formed ; the hydrogen nitrate splitting up more readily than other nitrates. Nitrate of ammonium [Ammonii Nitras, U. S. P.) is readily formed on neutralizing nitric acid with carbonate of ammonium. It occurs in long prismatic crystals or in fused masses, soluble in about half its weight of water at- 70^ and in twice its weight of alcohol, and when heated, yields nitrous oxide, or laughing-gas (N2O). NH.NOg = N2O + 2H2O. Nitrous oxide is thus prepared for use as an anaesthetic. When required for inhalation, it should be washed from any possible trace of acid or nitric oxide, by being passed through solution of potash, and through solution of ferrous sulphate. Nitrous oxide is slightly soluble in warm water, more so in cold. By pressure it may be liquefied to a colorless fluid, and by simulta- neous cooling solidified. It supports combustion almost as well as oxygen. The five oxides of nitrogenfh^wOi now been mentioned, namely — Nitrous oxide N2O Nitric oxide* NO Nitrous anhydride . . N^O^ or Nitric peroxide* . . . NO2 Nitric anhydride . . . N2O5 ^ Nitrous oxide is a colorless gas not altered by exposure to air; nitric oxide is also colorless, but gives red fumes in the air ; nitrous anhydride is a red vapor condensible to a blue liquid; nitric peroxide is a red vapor condensible to an orange liquid ; nitric anhydride is a^ colorless crystalline solid. The two anhydrides by absorbing water yield respectively nitrous acid (HNO2) and nitric acid (HNO3). This series of compounds forms a good illustration of the doctrine of multiple proportions (p. 42). Third Analytical Reaction , — Direct the blov^pipe-flame on to charcoal until a spot is red-hot ; now place on the spot a fragment of nitrate ; deflagration ensues. * The specific gravities of these gases indfcate that NO and NO, are the correct formuloe, and not N2O2 and N 0^. 22 * 258 SALTS OF ACIDULOUS RADICALS. This reaction does not distinguish nitrates from chlorates. It is insufficient for the recognition of very small quantities of either class of salts, especially when they are mixed with other substances. Gunpoivder is an intimate mechanical mixture of 75 parts of nitre, 15 to 12 J parts of charcoal, and 10 to 12^ parts of sulphur. In burning it may be said to give sulphide of potassium (the white smoke, K 2 S), nitrogen (N), carbonic oxide (CO), and carbonic acid (CO 2 ) gases, though the decomposition is seldom complete. The sudden production of a large quantity of heated gas from a small quantity of a cold solid is sufficient to account for all the effects of gunpowder. Fourth Analytical Reaction . — To nitric acid or other nitrate add solution of “ sulphate" of indigo the color is discharged. Solution of Sulphate of Indigo f B. P. (Sulphindylic or Sul- phindigotic acid), is made by digesting 5 grains of dry finely pow- dered indigo in a small quantity of strong sulphuric acid in a test- tube for an hour, the mixture being kept hot by a water-bath ; the blue liquid is then poured into 10 ounces of sulphuric acid, the whole well shaken, set aside, and the clear liquid decanted. Free chlorine also destroys the color of this reagent. Indigo B. P. (CgH^NO) is a blue coloring-matter deposited wdien infusion of various species of Indigofera is exposed to air and slight warmth. Under these circumstances, indican^ a yellow transparent amorphous substance, soluble in 'water, breaks up into indigo, which is insoluble and falls as a sediment, and a sort of sugar termed indi- glucin. The indigo is collected, drained, pressed, and dried. By action of deoxidizing agents indigo is converted into soluble colorless indigogen, reduced indigo, or white indigo ; 1 part of powdered indigo, 2 of green sulphate of iron, 3 of slaked lime, and 200 of water, shaken together and set aside in a well-closed bottle, gives this colorless indigo. A piece of yarn, calico, or similar fabric, dipped into such a solution, and exposed to air, becomes dyed blue, depo- sition of insoluble indigo-blue occurring within the cells and vessels of the fibre. This operation is readily performed on the small scale, and forms a good illustration of the characteristic feature of the art of dyeing, namely, the introduction of soluble coloring-matter into a fabric by permeation of the walls of its cellular and vascular tissue, and the imprisonment of that coloring-matter by conversion into a solid and insoluble form [vide also p. 117). Pure indigo, or indigotin, may be obtained in beautiful needles by spreading a paste of indigo and plaster of paris on a tin plate, and when dry placing a lamp underneath, moving the latter from place to place as the indigo sublimes and condenses on the surface of the plaster. It may also be obtained in crystals by gently boiling finely powdered indigo with aniline, filtering while hot, and setting aside ; these crystals may be washed with alcohol. Hot paraffin may be employed instead of aniline. It is possible to obtain indigotin artificially. Distinction hetween nitric acid and other nitrates. — Presence of the qitric radical in a solution having been proved by the above reac- CHLORATES. 259 tions, its occurrence as the nitrate of a metal is demonstrated by the neutral, or nearly neutral, deportment of the liquid with test-paper and the detection of the metal — its occurrence as nitric acid by the sourness of the liquid to the taste and the effervescence produced on the addition of a carbonate. Antidote , — In cases of poisoning by strong nitric acid, solution of carbonate of sodium (common washing-soda) or a mixture of magnesia and water may be administered as antidotes. QUESTIONS AND EXERCISES. 444. Trace the origin of nitrates. 445. In what does cubic nitre differ, chemically, from prismatic nitre ? 446. Describe a process by which nitrate of potassium may be ob- tained artificially. 447. State the difference between nitrate of potassium, nitre, salt- petre, and sal prunella. 448. What group of elements is characteristic of all nitrates ? and what claim has this group to the title of radical ? 449. Mention the usual theory regarding the manner in which atoms are arranged in reference to each other in such salts as nitrate of potassium. 450. How is Nitric Acid prepared ? 45 L. Give the properties of nitric acid. 452. What reactions occur when strong nitric and hydrochloric acids are mixed? 453. How is nitric oxide prepared ? 454. Enumerate and explain the tests for nitrates. 455. Into what substances does nitric acid usually split when em- ployed as an oxidizing agent? 456. How is nitrous oxide prepared ? 457. Enumerate the five oxides of nitrogen. 458. What is the nature of gunpowder ? 459. Write a few sentences on the chemistry of indigo, one of the tests for nitric acid. 460. How is nitric acid distinguished from other nitrates? 461. What quantity of cubic nitre will be required to produce ten carboys of official nitric acid, each containing 114 pounds? — Ans. 1076| pounds. CHLORIC ACID AND OTHER CHLORATES. Formula of Chloric Acid HCIO 3 . Molecular weight 84.5. Hypochlorous Acid (HCIO), and other Hypochlorites. Place a few grains of red oxide of mercury in a test-tube, half-fill the tube with chlorine- water and well shake the mix- 260 SALTS OF ACIDULOUS RADICALS. ture ; the resulting liquid is a solution of hypochlorous acid, mercuric oxychloride remaining undissolved : — 2HgO + 201, + up = 2IIC10 + Hg.,OCl,. By tlie double decomposition of hypochlorous aoid and oxides or hj^drates, other pure hydrochlorites are formed : — HCIO + NaHO = NaClO -f H^O. The direct action of chlorine on metallic hydrates is sup- loosed to give a mixture of chloride and hypochlorite, as described in connection with the S 3 mthetical reactions of Sodium (p. Y2, Liquor Sodm Chloratae^ B. P.) and Calcium (p. 96, Calx chlorata^ B. P.). Cl, + 2NaHO = NaCl,NaC10 + 11,0; 2C1, + 2CaH.p, = CaCl,,Ca2C10 + 2H,0. But the presence of chlorides cannot be directly demon- strated in these bodies ; so that their constitution is not definitely determined. The action of acids on them results in the evolution of chlorine; hence the great value of the calcium compound (chlorinated lime, or cldoride of lime) in bleaching operations: — CaCl„ Ca2C10 + 2H^SO, = 2C1, -f 2CaSO, + 2H,0. The solubility of hypochlorites in water, their peculiar odor, greatly intensified on the addition of acid, and their bleaching-powers (see the above calcium reaction) are the characters on which to rely in searching for hypochlorites. Chlorates. The group of elementary atoms represented by the formula CIO 3 is that characteristic of chloric acid and all other chlorates ; hence it is expedient to regard it as being an acidulous radical, which may be termed the chloric radical. Like the nitric radical, it has not been isolated. Chloric anhydride also (CI 2 O 5 ) unlike nitric anhy- dride, has not yet been obtained in the free condition. Chlorates are artificial salts. They are formed by simply boiling aqueous solutions of the common bleaching salts (chlorinated lime, chlorinated soda, chlorinated potash). Heat thus converts 5 NaCl Chloride of sodium. 5KC1 Chloride of potassium. 5CaCl Chloride of calcium. 3(NaCl, NaClO) ] ^ Chlorinated Soda. r into 3(KC1, KCIO) ] Chlorinated illto potash. I 3 (CaCl2, Ca2C10) ] Chlorinated ^ into lime. I NaClOg Chlorate of sodium. KCIO3 Chlorate of potassium. Ca2C103 Chlorate of calcium. and and I and I CHLORATES. 261 One chlorate may also be made from another by double decomposi- tion. In making chlorates economically the chlorinated salt is spe- cially prepared for, and in the same vessel as, the chlorate. Chlorate of Potassium. Thus Chlorate of Potassium {Potassii Chloras^ U. S. P.) is commercially made by saturating with chlorine gas a moistened mixture of three parts of chloride of potassium and ten of slaked lime, and well boiling the product. Chlo- rinated lime is first formed ; this, on boiling with water, splits up into chloride of calcium and chlorate of calcium, and the latter reacting on the chloride of potassium yields chloride of calcium and chlorate of potassium. 6(Ca2HO) 4- 6C1, = 3(CaCl„Ca2C10) -f 3(CaCl2,Ca2C10) = Ca2C103 + bCaCl^; Ca2C103 + 2KC1 = CaCl, + 2KCIO3. The operation may be conducted on a small scale by rub- bing together in a mortar the above proportions of ingre- dients in ounces or half-ounces, adding enough water to make the whole assume the character of damp lumps, placing the porous mass in a funnel (loosely plugged with stones or pieces of glass) and passing chlorine gas (p. 24) up through the neck of the funnel. When the whole mass has become of a slight pink tint (due to a trace of perman- ganate) it should be turned into a dish, well boiled with water, filtered, the filtrate evaporated if necessary, and set aside; the chlorate of potassium crystallizes out in color- less rhomboidal plates, chloride of calcium remaining in the mother-liquor. In the official process, carbonate of potassium instead of chloride is used ; but otherwise it is similar to the method just described. Chlorinated potash and chlorinated lime are first formed — K2CO3 -f Ca2HO + Cl, = KCl, KCIO + CaCO.^ + H,0, 6(Ca2HO) -f 6C1, = 3(CaCl2,Ca2C10) -f 6H,0; these, on boiling with water, split up into chlorates and chlorides — 3(KC1, KCIO) = KCIO3 -i- 5KC1 3(CaCl2, Ca2C10) = Ca2C103 + 5CaCl„ the whole of the chloride of potassium and chlorate of calcium finally yielding chlorate of potassium and chloride of calcium, 2KC1 -h Ca2C103 = CaCl, -f 2KCIO3. Neglecting intermediate decomposition, the reactions may be repre- sented by the following equation ; — 262 SALTS OF ACIDULOUS RADICALS. 6CI2 K,C03 H- 6CaH,02 = 2KOIO3 4- CaCOg 4 - Clilorine. Carbouate of Hydrate of Chlorate of Carbonate of potassium. calcium. potassium. calcium. 5 CaCl 2 4 - 6 H, 0 . Chloride of Water, calcium. Chlorate of potassium is soluble in water to the extent of 6 or 7 parts in 100 at common temperatures. It is usually administered medicinally in aqueous solution, sometimes also in lozenges [Tro- cMsci Potassii Chloratis^ U. S. P.). Chlorate of potassium must on no account be rubbed with sulphur in a mortar or otherwise, friction of such a mixture resulting in violent explosion. Chlorate of potassium, when heated, yields chloride of potassium and oxygen, and is the salt commonly employed in the preparation of the gas for experimental purposes. But if the action be arrested when one-third of the oxygen has escaped, the residual salt is found to contain perchlorate of potassium (KCIO^) : — 2KCIO3 = KCIO, 4 - KCl 4 - 0 ,. Chloric acid (HCIO3) may be isolated, but is unstable, quickly decomposing into chlorine, oxygen, and perchloric acid ; some other chlorate [e.g. KCIO3) must therefore be used in studying the reac- tions of the chloric radical. Perchloric acid (HCIO4) may be obtained by distilling perchlorate of potassium with sulphuric acid; it is quite stable, and is occasionally administered in medicine. Table of the Chlorine Acids, Hydrochloric acid .... HCl. Hypochlorous acid .... HCIO. Chlorous acid HCIO^. Chloric acid HCIO3 Perchloric acid HCIO^. The chloric radical is univalent (CIO3). The acidulous radicals of the other chlorine acids are also univalent. Analytical Reactions ( Tests). First Analytical Reaction . — To solution of a chlorate (e. g. chlorate of potassium) add solution of nitrate of sil- ver; no precipitate falls, showing that the chlorine must be performing different functions to those it possesses in chlorides. Evaporate the solution to diyness, and place the residue in a small diy test-tube, or at once drop a fragment of a chlorate into a test-tube, and heat strongly; oxygen is evolved, and may be recognized by its power of reinflaming an incandescent match inserted in the tube. Boil the residue with water, and again add solution of nitrate of silver ; a white precipitate falls, having all the lOD ATES. 263 characters of chloride of silver, as described under hydro- chloric acid. This is a trustworthy test, and, omitting the recognition of the oxygen, may be applied in the detection of small quantities of chlorates. Second Analytical Reaction , — To a fragment of a chlorate add two or three drops of strong sulphuric acid; an explo- sive gas (CI 2 OJ is evolved, having a peculiar odor, some- what like chlorine, but deeper in color than that element. 3 KCIO 3 -f H^SO, = Glfi, + KCIO, + K,SO, -f H,0. Warm the upper part of the test-tube to 150° or 200° F., or introduce a hot wire ; a sharp explosion ensues, due to decomposition of the gas, peroxide of chlorine, into its elements. Third Analytical Reaction . — Heat a small fragment of a chlorate with hydrochloric acid ; a yellowish-green ex- plosive gas termed euclilorine,^ is evolved. Its color is deeper than that of chlorine, hence the name (from fv, eii,^ well, and ;^xcopoj, chldros^ green). In odor it resembles chlorine, and is probably a mixture of that element with one of the oxides of chlorine; Fourth Analytical Reactioni — Direct the blowpipe-flame on to charcoal until a spot is red-hot, and then place on the spot a fragment of a chlorate ; deflagration ensues as with nitrates. Bromates. Bromates are salts closely resembling chlorates and iodates. The formula of Bromic acid is HBrOg. Iodates. Iodic Acid {HIO3). — Iodine is boiled in a flask with five times its weight of the strongest nitric acid (sp. gr. 1.5), in a fume-cupboard, until all action ceases. On cooling, iodic acid separates in small pyramidal crystals. These are removed, the residual liquid evapo- rated to dryness to remove excess of nitric acid, the residue and the first crop dissolved in a small quantity of boiling water, and the solu- tion sot aside to crystallize. lodate of Potassium (KIO3). — Fowder together equal weights of iodine and chlorate of potassium ; to the mixture add twice its weight of water and about one-eighth of its weight of nitric acid ; warm the whole until iodine disappears, and evaporate quite to dryness over a water-bath. The residue dissolved in water forms “ Solution of lodate of Potash,” B. P. 264 SALTS OF ACIDULOUS RADICALS. In this reaction the small quantity of nitric acid furnishes corre- sponding amounts of nitrate of potassium and chloric acid. The chloric acid with iodine gives iodic acid and chlorine, thus : — 2HCIO3 + I2 = 2HIO3 + CI2. The iodic acid and some chlorate of potassium then yield chloric acid and iodate of potassium, HIO3 + KCIO3 = HCIO3 + KIO3 ; and the two reactions alternate until the whole of the iodine has dis- placed the whole of the chlorine. Iodate of potassium and sulphurous acid decompose each other with elimination of iodine (or with formation of a blue color, if starch be present). • Sulphurous acid occurring as an impurity in acetic and other acids may thus be detected. 2KIO3 + 5H2SO3 = I2 + SH^SO, + 2 KHSO, H2O. Ferric Iodate, or rather Oxyiodate (Fe204I03, is precipi- tated on adding solution of ferric chloride to solution of iodate of potassium. QUESTIONS AND EXEEOISES. 462. How may hypochlorous acids be formed? 463. What are the relations of hypochlorous acid to common bleaching powder? 464. By what reaction is chlorine eliminated from hypochlorites ? 465. State the general reaction by which chlorates are formed. 466. Give details of the preparation of chlorate of potassium. 467. Mention the properties of chlorate of potassium. 468. What decompositions occur when chlorate of potassium is heated? 469. Find the molecular weight of chlorate of potassium. 470. What weight of oxygen is yielded when 1 oz. of chlorate of potassium is completely decomposed, and how much chloride of potas- sium remains? 471. One hundred cubic inches of oxygen, at 60^ F. and barometer at 30 inches, weighing 34.203 grains, and 1 gallon containing 277 cubic inches, what weight of chlorate of potassium will be required to yield 10 gallons of the gas? — Ans. ounces. 472. How many cubic inches of oxygen are producible from 1 oz. of chlorate of potassium ? 473. Calculate the weight of chlorate of potassium theoretically obtainable from 100 parts of chloride. 474. How is perchloric acid prepared ? 475. Enumerate the chlorine acids. 476. How may the presence of chlorides in chlorates be demon- strated ? ^ 477. Mention the tests for chlorates. ACETATES. 265 478. Give the formula of peroxide of chlorine. 479. What is euchlorine ? 480. How may iodic acid be made ? 481. Describe the preparation ofiodate of potassium. ACETIC ACID AND OTHER ACETATES. Formula of Acetic Acid HC2H3O2, or HA. Molecular weight 60. Source. — Acetic acid is said to occur naturally in certain plant juices and animal fluids in minute proportions, but otherwiae is an artificial product. Much is furnished by the destructive distillation of wood, hence the term 'pyroligneous acid for the crude product, a hybrid word from jtv^.pur, fire, and lignum wood. This impure pro- duct, neutralized by carbonate of sodium, the whole evaporated and the residue gently heated to drive off the volatile tarry matters, gives ace- tate of sodium, which after recrystallization furnishes by distillation with oil of vitriol and water acetic acid in a fair state of purity. In Germany and France large quantities of acetic acid are made by the spontaneous oxidation of the alcohol in inferior wines, hence the 'white- and red-wine vinegar [vinegar, from the French 'vin, wine, and aigre, sour). In England also the domestic form of acetic acid (brown*vinegar) has a similar origin : infusion of malt and unmalted grain is fermented ; and the resulting oxidation of its sugar, instead of being arrested when the product is an alcoholic liquid, a sort of beer, is allowed to go on to the next stage, acetic acid ; it usually contains from 3 to 6 per cent of real acetic acid (HC2H3O2). Vinegars. — The official vinegar [Acetum, U. S. P.) contains nearly (5.4) per cent. The so-called Vinegar of Oantharides [Acetum Cantharidis, B. P.) is a solution of the active principle of cantharides in very strong acetic acid, not in vinegar. The Vine- gar of Squill [Acetum Scilloe, B. P. and U. S. P.) is also a solution of the active principle of squill in dilute acetic acid, not in true vine- gar. The same may be said of Acetum Lobelice, U. S. P., Acetum Opii, U. S. P., and Acetum Sangumarice, U. S. P. (Vinegar of Bloodroot). Distilled vinegar [Acetum Destillatum, U. S. P.) is a form of Dilute Acetic Acid not now official in Great Britain. The Acetum Opii or Black Drop of America is made from nutmeg, saf- fron, and sugar, as well as Opium and Diluted Acetic Acid. In the British Pharmacopoeia, vinegar, except its use for its own sake, is only employed in the preparation of Emplastrum Cerati Saponis. The Acetic Radical. — The group of elements represented by the formula O2H3O2 is that characteristic of acetic acid and other ace- tates, and may, for convenience of study, be assumed to be an acidu- lous univalent radical. It has not been isolated, unless indeed a compound of similar composition, resulting from the action of perox- ide of barium on acetic anhydride, is the radical in question. Acetyl. — The characteristic grouping in acetates, C2H3O2, is fre- quently considered to contain, rather than to be, a radical — C2H3O, termed acetyl. Acetates may be made to yield a body having the 23 266 SALTS OF ACIDULOUS RADICALS. composition C.^H^OCl, which is regarded as chloride of acetyl ; from this may be obtained acetic anhydride (C^HgOg), which by absorbing water becomes acetic acid. C2H3O 1 Cl I Chloride of acetyl. C2H3O C2H3O Acetic anhydride. 0 CAOjo Acetic acid. 0,H,0|o Metallic acetates. The relation of acetic acid to alcohol will be evident from the fol- lowing equation representing empirically the formation of the acid : — C.,HgO + O 2 = C^H^O, + H.,0 Alcohol. Acetic acid. Acetates in aqueous solution are liable to decomposition. In solu- tion of acetate of morphia a myceloid growth occasionally forms, ace- tic acid disappears, and morphia is deposited. Solution of acetate of ammonium is liable to a similar change, gradually becoming alka- line. Synthetical Reaction, Acetic Acid. Synthetical Reaction, — To a few grains of acetate of sodium in a test-tube add a little water and some sulphuric acid, and heat the mixture ; acetic acid is evolved, and may be condensed by a bent tube adapted to the test-tube by a cork in the usual way. Acetic Acid. — This is the process by which acetate of sodium or calcium (the neutralized products of the distillation of wood) is made to yield acetic acid on the large scale. 'As with nitric and hydro- chloric acids, the loose term “ acetic acid” is that usually applied to aqueous solutions of acetic acid. The Acidum Aceticum, B. P., contains nearly 33 per cent, of real acid — that is, of HC2H3O.2 ; for it contains only 28 per cent, of acetic anhydride (C4Hg03). Its specific gravity is 1.044, the specific gravity of Acidum Aceticum^ U. S. P., being 1.047. Acidum Aceticum Dilutum, B. P. and U. S. P., con- tains per cent, of HC2II3O.2. Glacial acetic acid (HC2H3O2) contains no water. It solidifies to a crystalline mass at tempera- tures below 63*^ F., hence the appellation glacial (from glades, ice). Good commercial glacial acetic acid [Acidum Aceticum Glaciale, B. P.) does not contain more than 1 per cent, of water, corresponding | to 84.15 per cent, of acetic anhydride ; it solidifies at 34^, and again I liquefies at 48^: its specific gravity is 1.065. Although water is i lighter than this acetic acid, yet the addition of water at first renders j the acid heavier ; evidently therefore condensation, or contraction in 1 bulk, occurs on mixing the liquids : after 10 per cent, has been added, j the addition of more water produces the usual effect of dilution of a • heavy liquid by a lighter, namely, reduction of relative weight. This matter will be better understood after the subject of specific gravity has been studied. | ACETATES. 26 Y The following equation is expressive of the above reaction : — NaC,H 302 + H,SO, = + NaHSO, Acetate of Sulphuric Acetic acid. Acid sulphate sodium. acid. of sodium. or, assuming the existence of acetyl (O^HgO) in acetic acid, and a corresponding radical sulphuryl (SO 2 ) in sulphuric acid. , S04q _ 0^01 Q so, u . Na i ^ + H J “ H I ^ + NaH J ’ or, thirdly, on the assumption that salts contain the oxide of a basy- lous radical united with the anhydride of an acid (the old view under which such names as acetate of soda were formed), Na20,0,He03 + 2H20,S03 = Na20,H20,2S03 + H20,0,H603. Note on the Constitution of Salts. Which of these three equations, or, more broadly, which of the three views of the constitution of salts illustrated by the equations, is correct, it is impossible to say. Whether it is C. 2 H 3 O. 2 , O 2 H 3 O, or C^Hg 03 , which migrates from one acetic compound to another, whether it is SO4, SO2, or SO3, which migrates from one sulphuric compound to another, and so on with other acidulous groupings, cannot at present be determined. There are strong objections to each view ; and possibly neither is right. Either the given radicals cannot be isolated, or application of the forces of heat, light, and electricity do not confirm views arrived at by the results of operations with the chemical force ; or a salt comes to be regarded as having so large a number of constituent parts that the view, however true, breaks down in practice from the sheer inability of the mind to grasp the complicated analogies involved. Yet for the purposes of description, study, and conversation some system must be adopted. Let the first, then, be generally taken, over-reliance on it being checked by the use of general instead of special names for the hypo- thetical radicals, and other systems be employed in certain cases. (See also p. 253.) Impurity . — Acetic acid often contains sulphurous acid. The methods by which this impurity is detected are described on pages 264 and 274. Analytical Reactions ( Tests). First Analytical Reaction. — To an acetate add sulphuric acid and heat the mixture ; acetic acid, recognized by its odor, is evolved. Note 1. — Iodine, sulphurous acid, and other substances of power- ful odor mask that of acetic acid ; they must be removed, therefore, usually by precipitation or oxidation, before applying this test. Note 2. — It will be noticed that this reaction is identical with the previous one ; it has synthetical or analytical interest, according to the object and method of its performance. 268 SALTS OP ACIDULOUS RADICALS. Second Analytical Beaction. — Repeat the above action, a few drops of spirit of wine being first added to the acetate ; acetic ether (acetate of ethyl, €21150311302)5 also of charac- teristic odor, is evolved. The basylous radical ethyl (C 2 H 5 ) will be referred to subsequently. Third Analytical Reaction. — Heat a fragment of a dry acetate in a test-tube, and again notice the odor of the gaseous products of the decomposition, among them is acetone (C^HgO), the smell of which is characteristic. Car- bonate of the metal remains in the test-tube. Fourth Analytical Reaction. — To a solution of an acetate, made neutral by the addition of acid or alkali, as the case may be, add a few drops of neutral solution of perchloride of iron ; a deep-red liquid results, owing to the formation of ferric acetate (Fe26C2H302). Note . — It will be noticed that the formation of characteristic pre- cipitates, the usual method of removing radicals from solution for recognition, is not carried out in the qualitative analysis of acetates. This is because all acetates are soluble. Acetate of silver ( AgC 2 H 302 ) and mercurous acetate (HgC 2 H 302 ) are only sparingly soluble in cold water, but the fact can seldom be utilized in analysis. Hence pecu- liarities of color and odor, the next best characters on which to rely, are adopted as means by which acetates may be detected. Acetates, like other organic compounds, char when heated to a high tempera- ture. QUESTIONS AND EXERCISES. 482. What is the formula of acetic acid ? 483. State the relation of acetic acid to other acetates. 484. What is the molecular weight of acetic acid V 485. Name the sources of acetic acid. 486. What is pyroligneous acid ? 487. From what compound is the acetic acid of foreign and Eng- lish vinegar immediately derived ? 488. How much real acid is contained in official vinegar ? 489. What is the nature of the “ Vinegars” of Pharmacy ? 490. How may acetic acid be obtained from acetate of sodium ? 491. How much real acid is contained in the official acetic acid ? 492. Mention Ihe strength of commercial glacial acetic acid. 493. Give three or more views of the constitution of acetates, illustrating each by formulae. 494. Enumerate the tests for acetates, SULPHIDES. 269 HYDROSULPHURIC ACID AND OTHER SULPHIDES. Formula of Hydrosulphuric Acid H 2 S. Molecular weight 34. Source mid Varieties of Sulphur. — The acidulous radical of hy- drosulphuric acid, sulphydric acid, or sulphuretted hydrogen, and other sulphides, is the element sulphur (S). It occurs in nature in combination with metals, as already stated in describing the ores of some of the metals, and also in the free state. Most of the sulphur used in medicine is imported from Sicily, where it occurs chiefly asso- ciated with blue clay. It is purified by fusion, sublimation, or distil- lation. Melted and poured into moulds, it constitutes a crystalline mass termed roll sulphur. If distilled and the vapor carried into large chambers, so that it may be rapidly condensed, the crystals are so minute as to give the sulphur a pulverulent character; this is sub- limed sidphur {Sulphur Sublimatum, B. P. and U. S. P.) or flowers of sulphur : the same washed constitutes Sulphur Lotum, U. S. P. 4'he third common form, milk of sulphur, will be noticed subse- quently. Sulphur also occurs in nature in combination as a constitu- ent of animal and vegetable tissues, as sulphurous acid gas (SQ.^) in volcanic vapors, and as sulphuretted hydrogen in some waters, as those of Harrogate. Plastic sulphur is one of the allotropic varieties of the element, obtained on heating sulphur considerably beyond its melting-point and pouring into cold water. Quantivalence. — Sulphur is sexivalent, as seen in sulphuric anhy- dride (SO3), a substance which will be noticed under sulphuric acid. It also occasionally exhibits quadrivalent (SO 2 ) and still oftener bivalent affinities (H 2 S). Molecular weight. — At very high temperatures sulphur follows the rule that, under similar circumstances of heat and pressure, atomic weights (in grammes, grains, etc.) of elements occupy equal volumes of vapor ; its formula therefore is 83 , and molecular weight 64. At lower temperatures the volume weighs three times as much as it should do if following usual laws, and then the molecule would appear to contain six atoms (S^). Acid Salts. — Sulphur (S") being the first acidulous radical of bivalent activity met with in these sections on acids, it is desirable here to draw attention to a new class of salts to which such a radical will generally give rise. These are acid salts, which are intermediate between normal salts and acids. Univalent radicals with an atom of hydrogen give an acid, and with an atom of other basylous radi- cals an ordinary or normal salt. But bivalent radicals, from the fact that they give with two atoms of hydrogen an acid, and with two atoms of univalent metals a normal salt, may obviously give inter- mediate bodies containing one atom of hydrogen and one atom of metal ; these are appropriately termed acid salts : they are neither normal acids nor normal salts, but acid salts. (Examples : — KHCO 3 , NaHSO,, KHC 4 H 4 O,, Na 2 HPO„ CuHAsO^, CaH,2PO,.) Whether or not these salts give an acid reaction with blue litmus paper depends on the strength of the respective radicals. Usually 23 * 270 SALTS OF ACIDULOUS RADICALS. they do redden the test-paper, but sometimes not; thus the acid sul phide or sulphydrate of potassium (KHS), of sodium (NallS), or am- monium (AmllS) has alkaline properties.* Synthetical Reactions. Sulphuretted Hydrogen. First Synthetical Reaction. — The preparation of sulphu- retted hydrogen This operation was described on page 81, and probably has already been studied by the reader. Precipitated Sulphur. Second Synthetical Reaction. — Prepare the variety of the radical of sulphides known as Precipitated Sulphur {Suh phur Fraecipitatum^ B. P. and XJ. S. P.) or 7nz7^ of sulphur by boiling a few grains of flowers of sulpliur (5 parts) with slaked lime (3 parts) (10 parts U. S. P.) and some water (20 parts) in a test-tube (larger quantities in an evapo- rating-basin), filtering, and (reserving a small portion of the filtrate) adding dilute hydrochloric acid until the well- stirred liquid has a faint acid reaction on test-paper; sul- phur is precipitated, and maybe collected on a filter, washed, and dried (at about 1 20°). Excess of acid must be avoided, or hydrosulphyl, the liquid persulphide of hydrogen (H^S.^) will be formed, causing the particles of sulphur to aggre- gate to a gummy mass. This is the process of the Pharmacopoeias. Polysulphide of cal- cium and hyposulphite of calcium are formed : — SCaH^O^ + 6S, = 2CaS5 -f CaS.Og 4- 3H,0 Hydrate of Sulphur. Folysulpbide Hyposulphite Water. calcium. of calcium. of calcium. On adding the acid, both salts are decomposed and sulphur sepa- rates : — 2CaS. -f- CaS^Og -f 6HC1 = SCaCl^ + 311., 0 -f 6S., Poly.*5ulphide Hyposulphite Hydrochloric Chloride of Water. Sulphur, of calcium. of calcium. acid. calcium. Polysulphide of calcium alone would yield sulphuretted hydrogen as well as sulphur on the addition of acid. Hyposulphite of calcium alone would yield sulphurous acid gas as well as sulphur. If these * Some chemists regard these siilphydrates as compounds of basy- lous radicals with liS, a univalent grouping termed hydrosulphyl (per- sulphide of hydrogen, just as hydrates are similarly viewed as compounds of the univalent radical hydroxyl (HO) (peroxide of hy- drogen, H 2 O.,) — 11,8 becoming UlIS or fills (hydrosulphylide of hydro- gen), and H.,0 becoming llHO or HHo (hydioxylide of hydrogen). SULPHIDES. 2n gases are formed in the above operation, they at once react and give sulphur and water, very little, if any, sulphuretted hydrogen escaping. + 280., = 38^ + 4H2O. Impure Precipitated Sulphur . — To a sulphur solution prepared as before (or to the reserved portion) add sul- phuric acid ; the precipitate is in this case largely mixed with sulphate of calcium : — -f CaSA + 3H,S0, = SCaSO, + 3H,0 + 68^ Polysulphide Hyposulphite Sulphuric Sulphate of Water. Sulphur, of calcium. of calcium. acid. calcium. Place a little of each of these specimens of precipitated sulphur with a drop of the supernatant liquid on a strip of glass, cover each spot with a piece of thin glass, and exa- mine the precipitates under a microscope ; the pure sulphur will be found to consist of minute grains or globules, the impure to contain comparatively large crystals (sulphate of calcium). Note . — By far the larger proportion of precipitated sulphur met with in trade still (1873) contains, to the knowledge of the Author, sulphate of calcium, most specimens affording two-thirds of their weight of that substance. Moreover, this adulteration has been so persistently practised that many persons have become sufficiently accustomed to the satiny appearance of the impure article to regard the pure article with suspicion, sometimes refusing to purchase it. To ascertain the amount of sulphate of calcium in an impure speci- men of precipitated sulphur, place a weighed quantity in a tared crucible and heat till no more vapors are evolved. The weight of the residual anhydrous sulphate of calcium (Ca804=136), with one- fourth thereof added, is the amount of crystalline sulphate of calcium (Ca804, 2H20 = 172) present in the original quantity of impure sulphur. Pharmacists should refuse all parcels of sulphur which yield a white ash when a little is burnt off on the end of a table-knife or spatula. (No more damage is done to the steel than a rub on a knife-board will remove.) Analytical Reactions ( Tests). To a sulphide add a few drops of h^^drocdiloric acid ; sulphuretted hydrogen will probably be evolved, well known by its smell. If the sulphide is not acted upon by the acid, or if free sulphur be under examination, mix a minute portion with a fragment of solid caustic potash or soda, and fuse on a silver coin or spoon. When cold, place a drop of dilute hydrochloric acid on the spot, sul- phuretted hydrogen is evolved, and a black stain, due to sulphide of silver (Ag^S), left on the coin. 272 SALTS OF ACIDULOUS RADICALS. Other sulphur reactions may be adopted as tests, but the above are sufficient for all ordinary purposes. The most convenient re- agent for detecting sulphur in solution of ammonia is ammonio-sul- phate of copper, which gives a black precipitate of sulphide of copper if sulphur be present. The Iodide of Sulphur (S.J 2 ) lias been mentioned under “ Iodine.” A chloride (S 2 CI 2 ) and bromide (S 2 Br 2 ) may also be formed from their elements. A mixture of sulphur and chloride of sulphur is sometimes met with under the name of hypochloride of sulphur. QUESTIONS AND EXEKCISES. 495. In what form does sulphur occur in nature ? 496. State the modes of preparation of the three chief commercial varieties of sulphur. 497. To what extent does the atom of sulphur vary in quantiva- lence ? 498. State the relations of acid salts to acids and to normal salts. 499. Define sulphides and sulphydrates. 500. Describe the preparation of sulphuretted hydrogen. 501. What are the characters of pure precipitated sulphur? 502. Give equations explanatory of the reactions which occur in precipitating sulphur according to the official process. 503. Describe the microscopic test for impure precipitated sulphur. 504. Mention a ready physical method of detecting the adultera- tion of precipitated sulphur by sulphate of calcium. 505. Mention the tests for sulphides, and the character by which sulphurretted h^-drogen is distinguished from other sulphides. 506. How are sulphides insoluble in acids tested for sulphur ? 507. Give a method for the detection of a trace of sulphur in solu- tion of ammonia. SULPHUROUS ACID AND OTHER SULPHITES. Formula of sulphurous acid H 2 SO 3 . Formula of sulphurous acid gas or sulphurous anhydride, commonly termed sulphurous acid, ISO 2 . Molecular weight of sulphurous acid 82 ; of the gas 64. AVhen sulphur is burned in the air it combines with oxygen and forms sulphurous acid gas (SO 2 ), more correctly termed sulphurous anh 3 xlride, or commonly, but erroneously, sulphurous acid. It is a pungent, colorless gas, readily liquefied on being passed through a tube externally cooled by a freezing-mixture composed of two parts of well-powdered ice (or, better, snow) with one part of common salt. If sulphurous acid gas becomes moist or is passed into water, heat is evolved and true sulphurous acid (II 2 SO 3 ) formed. The latter body may be obtained in crystals ; but it is very unstable, and hence the properties of the sulphurous radical must be studied under the form SULPHITES. 213 of some other sulphite; sulphite of calcium (CaSOg), or sulphite of sodium (Na2S03), may be used for the purpose. Quantivalence . — The radical of the sulphites is bivalent (SO3"), and hence forms acid sulphites, such as acid sulphite of potassium (KHSO3) and normal sulphites, such as sulphite of sodium (Na2S03)* Note on Nomenclature . — The sulphites are so named from the usual rule, that salts corresponding* with acids whose names end in ous have a name ending in ite. They are generally made by pass- ing sulphurous acid gas over moist oxides or carbonates — in the latter case carbonic acid gas escaping. Synthetical Reaction. — To a few drops of sulphuric acid in a test-tube add a piece of charcoal and apply heat; sul- phurous acid gas is evolved, and may be conveyed by a bent tube into a small quantity of cold water in another test-tube. Larger quantities may be made in a Florence flask. The product is the Aciduni Sulphurosnm^ B. P. and XJ. S. P. It is said to contain, if saturated, nearly 12 (11.79) per cent, of sulphurous acid (H^SOg) or about 9 (9.2) per cent, of the gas (SO^). The process is also that described in the Pharmacopoeia, except that the gas is purified by passing through a small wash-bottle before final collection. Specific gravity 1.04 (1.035, IT. S. P.). Sulphurous acid may also be made by boiling copper, mercury, or iron with sulphuric acid, sulphates of the metals being formed. Also by boiling sulphur with sul- phuric acid. If in this process the water were replaced by solutions of or solid metallic oxides or carbonates, sulphites of the various metals would be formed. The formula of sulphite of potassium {Potassu Sulphis, U. S. P.) is K2S03,2E[2f^ ; of sulphite of sodium (Sodu Sulphis, U. S. P.) Na2S03,7H20 ; of the bisulphite or acid sulphite NaH S03. Under the name of antichlor the former is used for removing traces of chlorine from paper pulp. Sulphite of magnesium crystallized from a strong solution of sulphurous acid in water has the formula MgS03,6H20. 4H2SO, + C2 = 2CO2 + 4H2O -f 4SO2 Sulphuric Carbon Carbonic Water. Sulphurous acid. (charcoal). acid gas. acid gas. SO2 + IT,0 = H2SO3 Sulphurous Water, Sulphurous acid gas. acid. Analytical Reactions ( Tests). First Analytical Reaction. — To a sulphite (of sodium, for instance — made by passing sulphurous acid into solution of carbonate of sodium) add a drop or two of dilute hydro- 274 SALTS OF ACIDULOUS RADICALS. chloric acid; sulphurous acid gas escapes, known by its peculiar pungent smell. This smell is the same as that evolved on burning lucifer matches that have been tipped with sulphur. It is due, probably, not to the gas (SO 2 ), but to sulphurous acid (HgSOg) formed by the union of sulphurous acid gas with either the moisture of the air or that on the surface of the mucous membrane of the nose. It is highly suffo- cating. Second Analytical Reaction . — To a sulphite add a little water, a fragment or two of zinc, and then hydrochloric acid ; sulphuretted hydrogen will be evolved, known by its putrid odor and action on a piece of paper placed like a cap on the mouth of the test-tube, and moistened with a drop of solution of acetate of lead, black sulphide of lead being formed. Sulphurous acid may be detected in acetic acid, or in hydrochloric acid, by this test. H.SOg + Hg = H^S + 3II2O. Other Analytical Reactions. To solutions of neutral sulphites add nitrate or chloride of barium, chloride of calcium, or nitrate of silver ; in each case white sulphites of the various metals are precipi- tated. The barium sulphite is soluble in weak hydrochloric acid ; but if a drop or two of chlorine-water is first added, barium sulphate is formed, which is insoluble in acids. The other precipitates are also soluble in acids. The silver sul- phite is decomposed on boiling, sulphuric acid being formed, and metallic silver set free. To recognize the three radicals in an aqueous solution of sulphides, sulphites, and sulphates, add chloride of barium, filter, and wash the precipitate. In the filtrate sulphides are detected by the sulphu- retted hydrogen involved on adding an acid. In the precipitate sulphites are detected by the odor of sulphurous acid produced on adding hydrochloric acid, and sulphates by their insolubility in the acid. QUESTIONS AND EXERCISES. 508. What are the differences between sulphurous acid and sul- phurous acid gas, sulphites and acid sulphites ? 509. State the characters of sulphurous acid gas. 510. IIow is the official Sulphurous Acid prepared ? 511. By what test may sulphurous acid be recognized in acetic acid ? 512. Give a method by which sulphites may be detected in pre- sence of sulphides and sulphates. SULPHATES. 275 SULPHURIC ACID AND OTHER SULPHATES. Formula of Sulphuric Acid H2SO4. Molecular Weight 98 . Sulphates occur in nature ; but the common and highly important hydrogen sulphate, sulphuric acid, is made artificially. Preparation of Sulphuric Acid, General Nature of the Process, — Sulphur itself, or sometimes the sulphur in iron pyrites, is first converted into sulphurous acid gas by burning in air, and this gas, by moisture and oxygen, into sulphuric acid (S02+H204-0=H2S04). Details of the process. — The oxygen necessary to oxidize the sul- phurous acid gas cannot directly be obtained from air, but indirectly, the agency of nitric oxide (NO) being employed — this gas becoming nitric peroxide (NO2) by action of the air, and the nitric peroxide again becoming nitric oxide by the action of the sulphurous acid gas, and so on. A small quantity of nitric oxide gas will in this way act as carrier of oxygen from the air to very large quantities of sulphur- ous acid. The following equations represent the successive steps : — S2 + 2O2 = 2SO2 Sulphur. Oxygen Sulphurous (of the air). acid gas. SO2 4 - H2O = H2SO3 Sulphurous Water. Sulphurous acid gas. acid. 2 NO -f O2 = 2NO2 Nitric Oxygen Nitric oxide. (of the air), peroxide. B,SO, + NO, = H,SO, + NO Sulphurous Nitric Sulphuric Nitric acid. peroxide. acid. oxide. On the large scale the sulphurous acid gas is produced by burning sulphur in furnaces; it is carried, togethev with the nitric vapors, by fiues into leaden chambers, where jets of steam supply the neces- sary moisture ; the steam also, condensing, prevents other reactions. The resulting dilute sulphuric acid is concentrated by evaporation in leaden vessels. The nitric peroxide is in the first instance obtained from nitric acid, and this from nitrate of potassium or sodium by the action of a small quantity of the sulphuric acid of a previous operation. 2NaN03 Nitrate of sodium. + H,SO, Sulphuric acid. Na^SO^ + 2HNO5 Sulphate of Nitric sodium. acid. 3H2SO3 + 2HNO3 Sulphurous Nitric acid. acid. 3ELSO4 -h H ,0 + 2 NO Sulphuric Water. Nitric acid. oxide. Other processes. — Sulphuric acid may be obtained by other pro- cesses, as by distilling the sulphate of iron resulting from the natural oxidation of iron pyrites by air ; but it is seldom so made at the present day. The sulphate of ir.on was formerly called green vitriol, and the distilled product oil of vitriol, in allusion to its consistence and origin. 276 SALTS OF ACIDULOUS RADICALS. Experiment. — For purposes of practical study, a small quantity may be made by passing, a, sulphurous acid gas (p. 272), h, nitric oxide (p. 257), c, air (forced through by aid of bellows or a gas- holder), and, occasionally, d, steam (generated in a Florence flask) through glass tubes, nearly to the bottom of a two- or three-quart •flask, . S0., + H,0 = H 2 S 03 ; I 2Nt) + 02 = 2N0,; H2SO3 -f NO2 = H^SO, -f NO. A slow current of sulphurous acid gas, air, and steam, and a small quantity of nitric oxide, will furnish, in the course of a few minutes, enough sulphuric acid for recognition by the first of the following analytical reactions. Purification. — Sulphuric acid may contain arsenic, nitrous com- pounds, and salts. Arsenic may be detected by the hydrogen-test (p. 149), nitrous compounds by powdered sulphate of iron (which ac- quires a violet tint if they are present), and salts by the residue left on boiling a little to dryness in a crucible in a fume-chamber. If only nitrous compounds are present, the acid may be purified by heating with about half per cent, of sulphate of ammonium — water and nitrogen being produced (Pelouze). If arsenic occurs, boil with a small quantity of hydrochloric acid, which converts the arsenic into chloride of arsenicum ; or heat with a little nitric acid, which con- verts arsenious (As.^Og) into arsenic anhydride (As.^05), sul- phate of ammonium, and distil in a retort containing pieces of quartz and heat by an annular-shaped burner (to prevent “ bumping”). The arsenic anhydride remains in the retort. (Arsenious anhydride would be carried over with the sulphuric-acid vapors.) By distillation the acid is also purified from salts (such as NaHSO^) which are not volatile. Quantivalence. — The sulphuric radical being bivalent (SO/'), acid as well as normal sulphates may exist. Acid sulphate of potassium (KHSO4) is an illustration of the former, sulphate of sodium (Na.^SOJ of the latter ; double sulphates may also occur, such as that of potas- sium and magnesium (K2SO4, MgSO^, 6H2O). Sulphates generally contain water of crystallization. Pure sidphuric acid (H2SO4) is of specific gravity 1.848. The best “ oil of vitriol” of commerce, a colorless liquid of oily consis- tence, is of specific gravity 1.843, and contains 96,8 per cent, of real acid (H2SO4). This is the Acidum Sulphuricum, B. P. and U. S. P. The Acidum Sulphuricum Dilutum, B. P., sp. gr. 1.094 (U. S. P. 1.082) contains about I3J- (13 64) per cent, of acid (II2SO4) ; and the Acidum Sidphuricum Aromaticum, B. P. and U. S. P., a ! dilute acid in which are dissolved the soluble aromatic parts of cinna- j; mon and ginger, also contains nearly I3J (13.36) per cent, of acid 1 (II2SO4). There are some definite compounds of sulphuric acid with || water ; the first (H2SO4, 11., 0) may be obtained in crystals. ij Sulphuric anhydride (SO2) is a wdiite silky crystalline solid, having no acid properties. It is made by distilling sulphuric acid Avith phosphoric anhydride (311.2804+ P2O5 =2Il3P04+ 3SO3). I appears to unite with sulphuric acid and some other normal sul- ) phates to form compounds (R'2S04, SO3) resembling in constitution i SULPHATES. 277 red chromate of potassium or borax. The fuming sulphuric acid SO3), made at Nordhausen in Saxony, seems to be such a body. Note . — Sulphuric acid is a most valuable compound to all chemists and manufacturers of chemical substances. It is the key by which hundreds of chemical salts are unlocked, and their contents utilized. To describe its uses would be to write a work on chemistry. Analytical Reactions (Tests). Fii^st Analytical Reaction. — To solution of a sulphate add solution of a barium salt ; a white precipitate of sul- phate of barium (BaSOJ falls. Add nitric acid and boil the mixture, the precipitate does not dissolve. This reaction is as highly characteristic of sulphates as it has been stated to be of barium salts [vide page 88). The only error likely to be made in its application is that of overlooking the fact that nitrate and chloride of barium are less soluble in strong acid than in water. On adding the barium salt to the acid liquid, therefore, a white precipitate may be obtained, which is simply the nitrate or chloride of barium. The appearance of such a precipitate differs con- siderably from that of the barium sulphate ; hence a careful operator will not be misled. Should any doubt remain, water should be added, which will dissolve the nitrate or chloride, but not affect the sulphate. Second Analytical Reaction. — Mix a fragment of an in- soluble sulphate (BaSO^ e. g.) with carbonate of potassium or of sodium ; or, better, with both carbonates, and fuse the mixture in a small crucible. Digest the residue when cold, in water, and filter ; the filtrate may be tested for the sulphuric radical. This is a convenient method of qualitatively analyzing insoluble sulphates, such as those of barium and lead. Third Analytical Reaction. — Mix a fragment of an in- soluble sulphate with a little alkaline carbonate on a piece of charcoal, taking care that some of the charcoal-dust is included in the mixture. Heat the little heap in the blow- pipe*flame until it fuses, and, when cold, add a drop of acid ; sulphuretted hydrogen is evolved, recognized by its odor. This is another process for the recognition of insoluble sulphates. Other preparations of sulphur, and sulphur itself, give a similar re- sult. It is therefore rather a test for sulphur and its compounds than sulphates only ; but the absence of other salts can generally, if neces- sary, be previously determined. 24 278 SALTS OF ACIDULOUS RA^DICALS. Note . — The presence of the sulphuric radical in a solution having been proved by the above reactions, its occurrence as the normal sul- phate of a metal is demonstrated by the neutral, or nearly neutral, deportment of the liquid with test-paper, and the detection of the metal — its occurrence as sulphuric acid or an acid sulphate by the sourness of the liquid to the taste, and the effervescence produced on the addition of a carbonate. Antidote . — In cases of poisoning by strong sulphuric acid, solution of carbonate of sodium (common washing-soda), magnesia and water, etc., may be administered as antidotes. QUESTIONS AND EXEECISES. 513. What is the formula of sulphuric acid, and what its molecular weight ? 514. How is it related to other sulphates ? 515. Write a short article on the manufacture ’ of sulphuric acid, giving diagrams. 516. How may nitrous compounds be detected in, and eliminated from, sulphuric acid ? 517. State the method by which the presence of arsenic is detected in sulphuric acid, and explain the process by which it may be re- moved. 518. Define sulphates, acid sulphates, and double sulphates. 519. What percentage of real acid is contained in commercial oil of vitriol? 520. State the strength of the official “diluted” and “aromatic” sulphuric acid. 521. By what process is sulphuric anhydride obtained from Nord- hausen sulphuric acid ? 522. Explain the reactions which occur in testing for sulphates. 523. Ascertain by calculation the weight of oil of vitriol (of 96.8 per cent.) necessary for the production of one ton of dry sulphate of ammonium. — Ans. 1718 pounds. 524. Name the antidotes in cases of poisoning by strong sulphuric acid. CARBONIC ACID AND OTHER CARBONATES. Formula of carbonic acid H.^CO.^. Molecular weight 62. Formula . of carbonic acid gas, or carbonic anhydride, commonly termed car- bonic acid, CO 2 . Sources . — Carbonates (compounds containing the grouping CO 3 ) are very common in nature, the calcium carbonate (CaCOg) being widely distributed as chalk, limestone, or marble. The hydrogen carbonate, true carbonic acid, is not known, unless, indeed, carbonic acid gas assumes that condition on dissolving in water (Aqua Acidi Carhonici, U. S. P.). Such a solution (see page 71) changes the CARBONATES. 2‘r9 color of blue litmus-paper, and the gas does not ; this may be because only the true acid (Pl.^COg) affects the litmus, or because the gas (CO 2 ) cannot come into real contact with the litmus without a me- dium. From the commonest natural carbonate, carbonate of calcium, are derived the carbonic constituents of the one most frequently used in medicine, carbonate of sodium. Carbonate of sodium is prepared from the chief natural salt, the chloride. After the chloride has been converted into sulphate (salt- cake) by sulphuric acid, 2NaCl + H 2 SO, = Na^SO, + 2HC1, the sulphate is roasted with limestone and small coal, by which car- bonate of sodium and sulphide of calcium are formed : — Na^SO, + C, + CaC 03 = CaS + Na^COg + 4CO. Carbonic oxide gas and a little carbonic acid gas from the excess of chalk escape ; the residual mass (black ash) is digested in water, in which the carbonate of sodium dissolves, the sulphide of calcium with a little oxide remaining insoluble. The solution is evaporated to dryness, and yields crude carbonate of sodium. This is roasted with a small quantity of sawdust, to convert any caustic soda resulting from the action of the lime on the carbonate, into normal carbonate. The product is soda-ash. Dissolved in water and crystallized, it constitutes the ordinary “ soda” used for washing purposes : recrys- tallized and sometimes ground, it forms the official carbonate of sodium {Sodii Carbonas, U. S. P.) (Na.^COg, lOH^O). The reac- tion is rendered more intelligible by regarding it as occurring in two stages : 1st, the reduction of the sulphate of sodium to sulphide by the carbon of the coal, Na^SO, + 0, = Na^S + 4C0 ; 2d, the reaction of the sulphide of sodium and carbonate of calcium, giving soluble carbonate of sodium, thus — Na^S + CaCO., = Na^COg + CaS. The sulphur in the residual sulphide of calcium may be recovered by exposure to air, and the subsequent action of hydrochloric acid. Some hyposulphite of 'calcium (CaS 203 ) is first formed and the action of the acid on this and undecomposed sulphide gives chloride of cal- cium, water, and sulphur. Carbonic acid gas (CO 2 ) is a product of the combustion of all carbonaceous matters. It is constantly exhaled by animals and inhaled by plants, its intermediate storehouse being the atmosphere, throughout which it is equally distributed by diffusion [vide p. 22) to the extent of about 4 parts in 10,000. A larger proportion than that just mentioned gives to confined air depressing effects, 4 or 5 per cent, rendering the atmosphere poisonous when taken into the blood from the lungs. Carbonic acid, however, may be taken into the stomach with beneficial sedative effects ; hence, probably, much of the value of such effervescing liquids as. soda-water, lemonade, and solutions of the various granulated preparations and effervescing 280 SALTS OF ACIDULOUS RADICALS. powders {vide p. 73). The gas liquefies on being compressed, and the liquid solidifies on being cooled. Carbonic acid gas is twenty-two times as heavy as hydrogen, and about half as heavy again as air. Reactions. Synthetical and Analytical Reactions, — 1. To a fragment of marble in a test-tube add water and then hydrochloric acid ; carbonic acid gas (COJ is evolved, and may be con- veyed into water or solutions of salts by the usual delivery- tube. This is the process of the British Pharmacopoeia, and the one usually adopted for experimental purposes. Passed into carbonate of sodium, the gas gives Sodii Bicarbonas (p. 69), and into carbonate of potassium, Potassii Bicarbonas (p. 58). On the large scale the gas is prepared from chalk or marble and sulphuric acid, frequent stirring promoting its escape. 2. Pass the gas into lime-water; a wdiite precipitate of carbonate of calcium (CaCOg) falls. Solution of subacetate of lead may be used instead of, and is perhaps even a more delicate test than, lime-water. The evolution of a gas on adding an acid to a salt, warming the mixture if necessary, the gas being inodorous and giving a wdiite precipitate with lime-water, is sufficient evidence of the presence of a carbonate. Carbonates in solution of ammonia, potash, or soda, may be detected by the direct addition of solution of lime. 3. Blow air from the lungs through a glass tube into lime-water; the presence of carbonic acid gas is at once indicated. The passage of a considerable quantity of normal air through lime-water produces a similar effect. A bottle containing lime-water soon becomes coated with carbonate of calcium from absorption of carbonic acid gas. 4. Fill a dry test-tube with the gas, by passing the delivery-tube of the above apparatus to the bottom of the test-tube. Being rather more than once and a half as heavy as the air (1.529), it will displace the latter. Prove the presence of the gas by pouring it slowly, as if a visible liquid, into another test-tube containing lime-water; the characteristic cloudiness and precipitate are obtained on gently shaking the lime-water. In testing for carbonates by bringing evolved gas into contact with lime-water, the preparation and adaptation of a delivery-tube may often be avoided by pouring the gas from the generating-tube into that containing the lime-water in the manner just indicated. CARBONATES. 281 5. Pass carbonic acid ^as through lime-water until the precipitate at first formed is dissolved. The resulting liquid is a solution of carbonate of calcium in carbonic acid water. Boil the solution ; carbonic acid gas escapes, and the carbonate is again precipitated. This experiment will serve to show how chalk is kept in solution in ordinary well-waters, giving the property of ‘‘ hardness,” and how the/wr or stone-like deposit in tea-kettles and boilers is formed. It should be here stated that sulphate of calcium produces similar hard- ness, and that these, with small quantities of the sulphate and car- bonate of magnesium, constitute the hardening constituents of w^ell- waters, a curd (oleate of calcium or magnesium) being formed when- ever soap is used with such waters. An enormous amount of soap is w^asted through the employment of hard water for washing-purposes. The hardness produced by the earthy carbonates is termed “ tempo- rary hardness,” because removable by ebullition ; that by the earthy sulphates ‘‘permanent hardness” because unaffected by ebullition. The addition of lime-water or a mixture of lime and water removes temporary hardness (reac. 2, page 280), and carbonate of sodium, “ washing soda,” both temporary and permanent hardness, in the latter case sulphate of sodium remaining in solution. Carbonate of barium (ground witherite) also decomposes sulphates of calcium and magnesium, sulphate of barium being precipitated and carbonates of calcium or magnesium formed ; the latter and the carbonates originally in the water may then be precipitated by ebullition or by the action of lime-water. But the injurious effects of barium salts on man and the lower animals prevents the carbonate being used for purifying water for drinking purposes, as by accident or an unfore- seen reaction a portion might become dissolved. QUESTIONS AND EXERCISES. 525. Name the chief natural carbonates. 526. What are the formulae of carbonic acid and carbonic acid gas? 527. Adduce evidence of the existence of true carbonic acid. Trace the steps by which the carbonic constituents of chalk are^Klgs^ryed to sodium by the process usually adopted in alkali- works— the^anufacture of “ soda.” 529. Carbonic acid gas is constantly exhaled from the lungs of animals ; why does it not accumulate in the atmosphere ? 530. What is the effect of pressure on carbonic acid gas ? 531. State the specific gravity of carbonic acid gas. 532. By what processes may carbonic acid gas be obtained for ex- perimental and manufacturing-purposes ? 533. Describe the action of carbonic acid gas on the carbonates of potassium or sodium. 534. How may carbonic acid be detected in expired air ? 24* 282 SALTS OF ACIDULOUS RADICALS. 535. To what extent is carbonic acid gas heavier than air ? 536. What quantity of chalk (90 per cent, pure) will be required to furnish the carbonic acid ^necessary to convert one ton .of car- bonate of potassium (containing 83 per cent, of K2CO3) into acid carbonate, supposing no gas to be wasted ? — Ans. 1500 lbs. 537. Define “ hardness” in water. 538. How may the presence of carbonates be demonstrated ? OXALIC ACID AND OTHER OXALATES. Formula of Oxalic Acid 2H2O. Molecular weight 126. Sources. — Oxalates occur in nature in the juices of some plants, as wood-sorrel, rhubard, the common dock, and certain lichens ; but the hydrogen oxalate (oxalic acid) and other oxalates are all made artificially. Many organic substances yield oxalic acid w^hen boiled with nitric acid, and an alkaline oxalate when roasted with a mixture of the hydrates of potassium and sodium. Experimental Process . — On the small scale, a mixture of nitric acid and loaf sugar yields the acid in the purest form, the two being boiled together for some time. Manufacturing Process. — On the large scale, sawdust is roasted with alkalies, resulting oxalate of sodium decomposed by lime with formation of oxalate of calcium, the latter digested with sulphuric acid, and the liberated oxalic acid (Oxalic Acid of Commerce, B. P.) purified by recrystallization (Oxalic Acid, Purified, B. P., Acidum Oxalicum, U. S. P.). ^ Quantivalence. — The elements represented by the formula CaO^ are those characteristic of oxalates. They form a bivalent group- ing; hence normal oxalates (R'2C204), and acid oxalates (R'HC20J exist. Salt of sorrel is a crystalline compound of oxalic acid with acid potassium oxalate, the crystals containing two molecules of water of crystallization (KHC2O4, H2C2O4, 2FI2O). Oxalate of iron [Ferri Oxalas, U. S. P.) is a crystalline powder made by precipitating a solution of sulphate of iron with oxalic acid. When heated in contact with air it decomposes with a faint combus- tion, and leaves a residue of not less than forty-eight per cent, of red oxide of iron. Ayialytical Reactions {Tests). First Analytical Reaction . — To solution of an oxalate (oxalate of ammonium e. g.) add solution of chloride of calcium ; a white precipitate falls. Add to the precipitate excess of acetic acid ; it is insoluble. Add hydrochloric acid ; the precipitate is dissolved. The formation of a w^hite precipitate on adding a calcium or barium salt, insoluble in acetic but soluble in hjnlroQhloric or nitric acid, is OXALATES. 283 usually sufficient proof of the presence of an oxalate. The action of the liquid on litmus paper, effervescence with carbonate of sodium, and absence of metals, would indicate that the oxalate is that of hydrogen, oxalic acid. Antidote . — In cases of poisoning by oxalic acid or salt of sorrel, chalk and water may be administered as a chemical antidote (with the view of producing the insoluble oxalate of calcium), emetics and the stomach-pump being used as soon as possible. Second Analytical Reaction . — Heat a fragment of a fixed metallic oxalate (an oxalate of potassium for example) in a test-tube ; decomposition occurs, carbonic oxide (CO) (a gas that will be noticed subsequently) is liberated, and a carbonate of the metal remains. Add water and then an acid to the residue ; effervescence occurs. This is a ready test for insoluble oxalates, and is trustworthy if, on heating the substance, no charring occurs. Organic salts of metals decompose when heated, and leave a residue of carbonate, but except in the case of oxalate, the residue is always accompanied by much charcoal. Other Analytical Reactions . — Nitrate of silver gives, with oxalates, white oxalate of silver (Ag2C20J. Dry oxalates are decomposed w^hen heated with strong sul- phuric acid, carbonic oxide and carbonic acid gases escap- ing. If much of the substance be operated on, the gas may be crashed with an alkali, the carbonic acid be thus removed, and the carbonic oxide be ignited ; it will be found to burn with a characteristic bluish flame. Oxa- lates, when mixed with water, black oxide of manganese (free from carbonates), and sulphuric acid, 3 deld carbonic acid gas, which may be tested by lime-water in the usual manner. Insoluble oxalates, such as those of calcium and magnesium, may be decomposed hy ebullition with solution of carbonate of sodium ; after filtration the oxalic radical will be found in the clear liquid as soluble oxalate of sodium. Test of Purity . — “ Purified oxalic acid .... is entirely dissi- pated by a heat below 350^ F.” (B. P.) QUESTIONS AND EXERCISES. 539. Explain the constitution of oxalates. 540. State how oxalates are obtained. 541. What is the quantivalence of the oxalic radical ? 542. Give the formula of “ salt of sorrel.” 284 SALTS OF ACIDULOUS RADICALS. 543 . Mention the chief test for oxalic acid and other soluble oxa- lates. 544 . Name the antidote for oxalic acid, and describe its action. 545 . By what reactions are insoluble oxalates recognized ? TARTARIC ACID AND OTHER TARTRATES. Formula of Tartaric Acid H2C4H^Og, or H2T. Molecular weight 150 . Sources. — Tartrates exist in the juice of many fruits ; but it is from that of the grape that our supplies are usually obtained. Grape-juice contains much acid tartrate of potassium, which is gradu- ally deposited when the juice is fermented, as in making wine ; for acid tartrate of potassium, not very soluble in aqueous liquids, is still less so in spirituous, and hence crystallizes out as the sugar of the grape-juice is gradually converted into alcohol. It is found with tartrate of calcium lining the vessels in which wine is kept ; and it is from this crude tartar* (argal or argol), as well as from what tartar may be remaining in the marc left after the juice has been pressed from the grapes, that tartaric acid and other tartrates are prepared. Cream of Tartar, purified by crystallization [Potassce Tartras Adda, B. P., Potassii Bitaftras, U. S. P.), occurs as a “gritty white powder, or fragments of cakes crystallized on one surface of a pleasant acid taste, soluble in 180 parts of cold and 6 of boiling water, insoluble in spirit. Quantivalence. — The elements represented by the formula C^H^Og are those characteristic of tartrates. They form a bivalent grouping ; hence normal tartrates tartrates (R'HT) exist. Tartrate of potassium, the Potassii Tartras of the U. S. Pharma- copoeia (K2C4H40g) and Rochelle Salt, or tartrate of potassium and sodium (KNa04H40g, 4H2O); the official Potassii et Sodii Tartras (Soda Tartarata, B. P.), are illustrations of normal tartrates, while Cream of Tartar is an example of acid tartrates. The only official tartrate not apparently included in these general formulae is tartar- emetic (Antimonium Tartaratum, B. P., Antimonii et Potassii Tartras, U. S. P.), which is sometimes regarded as the double tar- trate of potassium and a hypothetical radical, antimonyl (SbO), thus, KSb0C4H40g. Possibly, however, it is but an oxytartrate of anti- mony (Sb202T) with normal tartrate of potassium (KjT) ; for there are several oxycompoundsof antimony analogous to the oxycompounds * “It is called tartar^ says Paracelsus, “because it produces oil, water, tincture, and salt, which burn the patient as tartarus does.” Tartarus is Latin (Taprapof Tartaros, Greek) for hetl. The products of its destructive distillation are certainly somewhat irritating in taste and smell ; and the “ salt” (carbonate of potassium) that is left is diuretic, and, in larger quantities, powerfully corrosive. A boiling solution of tartar yields a floating crust of minute cry.stals on cooling, hence the term cream of tartar. TARTRATES. 285 of bismuth that have been described (p. 225 ), normal salts partially decomposed by water into oxides, and many of these oxycompounds readily unite with normal salts of other basylous radicals. Tartar emetic would thus be oxytartrate of antimony with tartrate of potas- sium (Sb202T, K2T, or Sb202C4H406, K20^H^Og). Tartaric Acid. Tartaric Acid [Acidum Tartaricum, B. P. and U. S. P.) is obtained, according to the British Pharmacopoeia, by boiling cream of tartar [Potassce Tartras Adda, B. P., Pbtassii Bitartras, U. S. P.) with water, adding chalk till effervescence ceases, and then chlo- ride of calcium so long as a precipitate falls ; the two portions of tar- trate of calcium thus consecutively formed are thoroughly washed, treated with sulphuric acid, the mixture boiled for a short time, re- sulting sulphate of calcium mostly separated by filtration, the filtrate concentrated by evaporation, any sulphate of calcium that may have deposited removed as before, and concentration continued until the solution is strong enough to crystallize. Tartrate of calcium from 9 ounces of cream of tartar requires 5 ounces by weight of sulphuric acid for complete decomposition. 2 KHT + CaCOg = CaT + K2T + H^O + OO2 Acid tartrate Carbonate of Tartrate of Tartrate of Water. Carbonic of potassium. calcium. calcium. potassium. acid gas. K 2 T + CaCl2 Tartrate of Chloride of potassium. calcium. CaT + 2 KC 1 Tartrate of Chloride of calcium. potassium. 2 CaT + 2H2SO, Tartrate of Sulphuric calcium. acid. 20 aS 0 , 4 - 2H2T Sulphate of Tartaric calcium. acid. Tartaric acid occurs in colorless crystals, or the same powdered. It is strongly acid and readily soluble in water or spirit. One part in 8 of water and 2 of spirit of wine forms “ Solution of Tartaric Acid,” B. P. Its aqueous solution is not stable. Parcels of tartaric acid often contain crystals of an allotropic or physically isomeric modification [vide “ Allotropy” and “ Isomerism” in Index). It is termed Paratartaric acid (rtapa, para, beside) or Racemic acid (racemus, a bunch of grapes), and is a combination of ordinary tartaric acid, whose solution twists a ray of polarized light to the right hand (dextrotartaric or dextroracemic acid) and of laevo- tartaric or laGvoracemic acid, whose solution twists a polarized ray to the left. Racemic acid is inactive in this respect, the opposite pro- perties of its constituents neutralizing each other. Racemic acid is less soluble in alcohol than tartaric acid. Reactions. Tartrate of Potassium. Synthetical Reactions , — To a small quantity of a strong solution of carbonate of potassium add acid tartrate of potassium so long as effervescence occurs ; the resulting 236 SALTS OF ACIDULOUS RADICALS. liquid is solution of normal tartrate of potassium {Potassii Tarlras^ U. S. P.) (K/f), crystals of which may be obtained on evaporation. Note. — This is a common method of converting an acid salt of a bivalent acidulous radical into a normal salt. The carbonate added need not be a carbonate of the same, but ma}^ be of a different metal; compounds like Rochelle salt (KNaT) are then obtained. Thus : — Tartrate of Potassium and Sodium. To a strong hot solution of carbonate of sodium add acid tartrate of potassium until effervescence ceases ; the resulting liquid is solution of tartrate of potassium and sodium; on cooling, it yields cr 3 ^stals. This is the official process {Soda Tartar ata^ B. P., Fotassii et Sodii Tartras^ ; U. S. P.) (KNaC,H,0„4H,0). | Nsi.CO, + 2KHC,H,Oe = 2KNaC,n,Og + H^O + CO^ Carbonate Acid tartrate Tartrate of potas- Water. Carbonic of sodium. of potassium. sium and sodium, acid gas. Crystals of Rochelle salt are usually halves of colorless, trans- parent, right rhombic prisms, slightly efflorescent in dry air, soluble in five parts of boiling water. Tartrate of potassium is slightly deliquescent, soluble in about four parts of boiling water. Equivalent Weights of Tartaric Acid, Carbonate of Potassium, Bicarbonate of Potassium, Carbonate of Sodium, Bicarbonate of Sodium, and Carbonates of Ammonium and Magnesium ; repeated for 2Q parts of each (and, incidentally, for other propor- tions.) Ta rt,. Acid H 3 C 4 H 4 O 6 — 150 20 18i! |l5 lOi 175 25i 3 I 5 Carb. Potas K 3 CO 3 (of 8 t per cent.). . . = 164 22 20 16i lU 19i 28 3U T?ica,rb. Pot, .... 2 (KHC 03 ) — 200 9R4 24i 20 14 235 34 42 Carb Soda (cryst.) Na,CO 3 , 10 HaO — 286 T 38 34f 28h 20 34 48i 60 Ricarb Sod 2 (NaHC 03 ) — 168 225 20 i 16| 115 20 28.} 351 Carb. Ammon.... (N 4 H,,C 303)--2 =118 15J Hi m 8i 14 20 245 Carb. Magnes (MgC03)3Mg2H0,4Ha0.... =95.5 12i m 95 65 ni 16 20 Thus 20 parts (grains or other weights) of tartaric acid neutralize 22 of carbonate of potassium, 26| of bicarbonate of potassium, 38 of carbonate of sodium, 22^ of bicarbonate of sodium, 15J of car- bonate of ammonium, or 12| of carbonate of magnesium. Other quantities of tartaric acid (18^, 15, 10^, 17J, 25^, 31^) saturate the amounts of salts mentioned in the other columns and vice versa. A similar Table for Citric Acid will be found at page 290, and for both acids in the Appendix. These Tables afford good illustrations TARTRATES. 28 T of the laws of chemical combination (page 40). The reader should verify a few of the numbers by calculation from the atomic weights of the elements concerned in the reactions, remembering that the salts formed are considered to be neutral in constitution. In medical practice effervescing saline draughts are often designedly prescribed to contain an amount of acid or alkali considerably in excess of the proportions required for perfect neutrality. A common form of Seidlitz Powder consists of 3 parts of Rochelle salt (120 grains) with 1 (40 grains) of acid carbonate of sodium (the mixture usually wrapped in blue paper), and 1 (40 grains) of tartaric acid (wrapped in white paper). When administered, the latter is dissolved in a tumbler rather more than half full of water, the former added, and the mixture drunk during effervescence. It will be seen that the salts swallowed are tartrate of potassium and sodium (KNaT^IH^O), tartrate of sodium (Na2T,2H20), and acid tartrate of sodium or potassium. The last-mentioned salt results because 11^ per cent. (4^ grains) of the tartaric acid is in excess of the quantity necessary for the formation of neutral tartrate of sodium. This amount of acid salt gives agreeable acidity to the draught. The United States formula (Palveres Effervescentes Aperientes, U. S. P.) includes rather less tartaric acid, so that only neutral salts are formed. Analytical Reactions (Tests), Fii'st Analytical Reaction, — To solution of any normal tartrate, or tartaric acid made neutral by solution of soda, add solution of chloride of calcium; a white precipitate, [tartrate of calcium, falls. Collect the precipitate on a filter, wash, place a small quantit}^ in a test-tube, and add I solution of potash; on stirring the mixture the precipitate dissolves. Heat the solution; the tartrate of calcium is again precipitated. The solubility of tartrate of calcium in cold potash solution enables the analyst to distinguish between tartrates and citrates, otherwise a difficult matter. Citrate of calcium is not soluble in the alkali. [The absence of much ammonical salt must be insured in both cases, .the precipitates being soluble in such liquids. I Second Analytical Reaction. — Acidulate a solution of a [tartrate with acetic acid, add acetate of potassium, and [well stir the mixture; a crystalline precipitate of acid tar- itrate of potassium slowly separates. Tlie precipitate being insoluble in alcohol, the addition of a little spirit of wine renders the test more delicate. This reaction is not applicable in testing for very small quantities of tartrates, the acid tartrate of potassium being not altogether insoluble. 288 SALTS OF ACIDULOUS RADICALS. Third Analytical Reaction . — To a neutral solution of a tartrate add solution of nitrate of silver ; a white precipi-, tate of tartrate of silver, Ag.^C4H^Og, falls. Boil the mix- ture ; it blackens, owing to the reduction of the salt to metallic silver. Other Reactions . — Tartrates heated with strong sulphu- ric acid char immediately. Tartaric acid and the soluble tartrates prevent the precipitation of ferric and other hy- drates by alkalies, soluble double tartrates being formed (which on evaporation yield liquids that do not crystallize, but, spread on sheets of glass, dry up to thin transparent plates or scales). The ferri et potassii tartras, U. S. P. {Ferruni Tartaratum.^ B. P.),is a preparation of this kind. Tartrates decompose when heated, carbonates being formed and carbon set free, the gaseous products having a peculiar, more or less characteristic smell, resembling that of burnt sugar. QUESTIONS AND EXERCISES. 546. State the origin of tartaric acid and other tartrates, and ex- plain the deposition of argol, crude acid tartrate of potassium, during the manufacture of wine. 547. What are the chemical formula and characters of “ cream of tartar ?” 548. Mention the formula and quantivalence of the tartaric radical. 549. Write formulae of normal, acid, and double tartrates, tartar- emetic being treated as an oxytartrate of antimony with tartrate of, potassium. 550. Give equations or diagrams illustrative of the production ofl tartaric acid from cream of tartar. 551. By what general process may normal or double tartrates be obtained from acid tartrate of potassium ? 552. Work out sums proving the correctness of some of the figures! given on p. 286 as showing the saturating power of tartaric acid for various quantities of different carbonates, and give diagrams or equa-: tions of the reactions. f 553. State the names and quantities of the salts resulting from the! admixture of 120 grains of tartrate of potassium and sodium, 40 grains of acid carbonate of sodium, and 40 grains of tartaric acid, (^Seidlitz powder). j 554. Enumerate the tests for tartrates, and explain the effects oil heat on tartrates of the metals. I I CITRATES. 289 CITRIC ACID AND OTHER CITRATES. Formula of Citric Acid HgCgH^O^, H 2 O or HgCiAq. Molecular weight 210. Source. — Citric acid [Acidum Citricum, B. P. and U. S. P.) ex- ists in the juice of many of our common garden fruits; thus the pulp of the fruit of Tamarindus indica ( Tamarindus, B. P. and U. S. P.) contains nearly 10 per cent, (in addition to 1.5 of tartaric acid, .5 of malic acid, and 3 per cent, of acid tartrate of potassium). But it is from the lemon or lime that the acid of commerce is usually ob- tained. Process. — The British Pharmacopoeia directs that the hot lemon- juice (4 pints) be saturated by powdered chalk (4^ ounces), the resulting citrate of calcium collected on a filter, washed with hot water till the liquor passes from it colorless (by which not only the coloring matter but the mucilage, sugar, and other constituents of the juice are got rid of), then mixed with cold water (1 pint), decom- posed by sulphuric acid (2^ fluidounces in IJpint of water), the mix- ture boiled for half an hour, filtered, the solution evaporated to a density of 1.21, set aside for 24 hours, then poured off from any de- posit of crystalline sulphate of calcium, further concentrated, and set aside to crystallize. 2H3CgH,0, + SCaCOg == Ca32CgH,07 + SH^O + 3CO., Citric acid Carbonate of Citrate of Water. Carbonic (impure). calcium. calcium. acid gas. 02^,20,11,0, + 3H,SO, = + 30aS0, Citrate of Sulphuric Citric acid Sulphate of calcium. acid. (pure). calcium. Quantivalence. — The elements represented by the formula CgHgO^ are those characteristic of citrates. They form a trivalent grouping ; hence three classes of salts may exist — one, two, or three atoms of the basylous hydrogen in the acid, HgCgH-O^, being displaced by equivalent proportions of other basylous radicals. Citric acid itself is the only citric compound of much direct im- portance to the pharmacist. It usually occurs in colorless crystals soluble in half their weight of boiling and three-fourths of cold water, less soluble in spirit, and insoluble in ether. A solution of about 34 grains in 1 ounce of water forms a sort of artificial lemon-juice. Citrates heated with strong sulphuric acid to about 212^ F. evolve carbonic oxide gas, and at higher temperatures acetone and carbonic acid gas. Action of heat on citric acid. — Citric acid slowly heated first loses its water of crystallization ; afterwards (347'^ F.) the elements of another molecule of water are evolved and a residue obtained from which ether extracts aconitic acid (HgCgHgOg), identical with the aconitic acid (and the acid first termed equisetic) in various species of A conitum and Equisetum. “ Effervescing Citrate of Magnesia f so-called, is generally a mixture of bicarbonate of sodium, citric acid, tartaric acid, sugar, either carbonate or sulphate of magnesium (sometimes neither) and 25 290 SALTS OF ACIDULOUS RADICALS. occasionally essence of lemon. True citrate of magnesium is easily made by heating together calcined magnesia and citric acid ; it is frequently prescribed in France in doses of two ounces. Liquor Magnesii Gitratis, U. S. P., is a bottled mixture of magnesia, citric acid, and syrup, with bicarbonate of potassium, and sufficient water to nearly fill the bottle, which is closed by a cork secured with twipe. The official Lemon Juice [Succus Limonum, B. P., Limonis Succus, U. S. P.) is to be freshly expressed from the ripe fruit, and contain an average of 32.5 grains of citric acid in 1 fluidounce. The acidity may be ascertained by adding solution of potash or soda (the strength of which has been previously determined with pure crystals of citric acid) till red litmus paper is fairly turned blue. Before ap- plying this test to commercial specimens, the absence of notable quantities of sulphuric, hydrochloric, acetic, tartaric, or other acid must be insured by application of appropriate reagents. Mistura Potassii Citratis, U. S. P., is lemon juice completely neutralized by bicarbonate of potassium. It is a slightly impure but flavored solution of citrate of potassium. Equivalent Weights of Citric Acid, Carbonate of Potassium^ Bicarbonate of Potassium, Carbonate of Sodium, Bicarbonate j of Sodium, and Carbonates of Ammonium, and Magnesium ; \ repeated for 20 parts of each (and, incidentally, for other propor- tions). Citric Acid H^CgHftO^HaO — 210 20 17 14 I 231 291 Carb. Potas (K 2 CO 3 ; of 81p.ct.)-^2X3 = 216i 23k 20 16^ lU ' 19f 28 341 Bicarb Pot 3(KHC03) — 300 28k 24i 20 14 24 34 411 Carb. Sod.(cryst.) (Na3CO3,10H2O)-^2X3.... = 429 40 34| 28h 20 134^ 48| 60 Bicarb. Sod 3(NaHC03) = 252 24 20 ^ 16J 113 90 2Sk 35 Carb. Ammon (N4H.,C30,)h-4X3 = 177 16 J llj 14 20 241 Carb. Magnes. . . . (MgC 03 ) 3 Mg 2 H 0 , 4 H 3 O -f-SX3 = 143i 13^ 9^ 6 | 1 4U 16i 20 Thus 20 parts (grains, or other weights) of citric acid neutralize 23|^ of carbonate of potassium, 28J- of bicarbonate of potassium, 40 of carbonate of sodium, 24 of bicarbonate of sodium, 16| of carbon- ate of ammonium, or 13|^ of carb. of magnesium. Other quantities of acid (17, 14, 9J, 16|, 23J, 29i) saturate the amounts of salts men- tioned in the other columns, and vice versa. This Table, the similar one for tartaric acid (p. 286), and that for both acids [vide Appendix) afford good illustrations of some of the laws of chemical combination (p. 40). The reader should verify a few of the numbers by calculation from the atomic weights ' of the elements concerned in the reactions, remembering that the 1 salts formed are considered to be neutral in constitution. In medical J practice, effervescing saline draughts are often designedly prescribed I to contain an amount of acid or alkali considerably in excess of the | proportions required for perfect neutrality. : CITRATES. 291 Analytical Reactions ( Tests), First Analytical Reaction. — To a dilute solution of any neutral citrate, or citric acid carefully neutralized by alkali, add solution of chloride of calcium and boil ; a white pre- cipitate, citrate of calcium (Ca 3 CiJ, falls. Treat the pre- cipitate as for tartrate of calcium (p. 281) ; it is not dissolved by the potash. A mixture of citrates and tartrates can be separated by this reac- tion. They are precipitated as calcium salts, and the washed pre- cipitate mixed with solution of potash, diluted, and filtered ; the fil- trate contains the tartrate, which is shown to be present by reprecip- itation on boiling. The precipitate still on the filter is washed, dis- solved in solution of chloride of ammonium, and the solution boiled ; the citrate of calcium is reprecipitated. The presence of much sugar interferes with this reaction. A dilute solution of a citrate is not precipitated by chloride of calcium until the liquid is heated : precipitation from a strong solution, also, is not thoroughly complete without ebullition of the mixture. Second Analytical Reaction. — To a neutral solution of a citrate add solution of nitrate of silver ; a white precipi- tate of citrate of silver (AggCi) falls. Boil the mixture ; the precipitate does not turn black as a tartrate of silver does. Other Analytical Reactions. — Citric acid forms no pre- cipitate corresponding with the acid tartrate of potassium. ■ Lime-water, in excess, gives no precipitate with citric acid or citrates, unless the solution is boiled, citrate of calcium being slightly soluble in cold but not in hot w^ater ; it usually precipitates tartrates in the cold. Citrates, when heated with strong sulphuric acid, do not char imme- diately. Citric acid and citrates prevent the precipita- tion of oxide of iron by alkalies, soluble double compounds being formed. The Ferri et Ammonii Gitras^ U. S. P., is a preparation of this kind. Metallic citrates decompose when heated, carbonates being formed and carbon set free : the odor of the gaseous products is not so characteristic as that of tartrates. QUESTIONS AND EXERCISES. 555. What is the source of citric acid ? 556. Describe the method by which citric acid is prepared, giving diagrams. 292 SALTS OF ACIDULOUS RADICALS. 557. Illustrate by formulae the various classes of tartrates and citrates. 558. State the average- proportion of citric acid in lemon-juice. 559. Work out the sums proving the correctness of some of the figures given on page 290 as showing the saturating-powcr of citric acid for various carbonates. 560. What are the tests for citrates? 561. How are the tartrates separated from citrates? PHOSPHORIC ACID AND OTHER PHOSPHATES. Formula of Phosphoric Acid HgPO^. Molecular weight 98. Source. — The source of the ordinary normal phosphates and of phosphorus itself [Plios'pliorus, B. P. and U. S. P.) is the normal phosphate of calcium (Ca^2P04). It is the chief constituent of the bones of animals, being derived from the plants on which they feed, plants again obtaining it from the soil. Compounds of phosphorus are also met with in the brain, nerves, muscles, blood, saliva, and, according to Kirkes, even in tissues so simple that one must assume tfiem to be necessary constituents of the substance of the primary cel]. They escape from the system both in the urine and faeces. Process. — Phosphorus (P = 31) is obtained from bones by the fol- lowing processes : The bones are burnt to remove all traces of animal matter. The resulting hone-earth is treated with sulphuric acid and water, by which an acid phosphate (CaH42P04), often called superphosphate of lime, is produced : — Ca32PO, + 2H,SO, = CaH,2PO, + 2CaSO,. The acid phosphate (strained from the sulphate)* is mixed with charcoal and sand, and heated to dull redness in an iron pot. At this stage water escapes and metaphosphate of calcium (Ca.^PO.^, see Index) remains : — OaH,2PO, = Ca2P03 + 2II2O. The mixture is then transferred to a retort and distilled at a strong red heat; silicate of calcium (CaSiOg) is formed and remains in the retort, phosphorus vapor is evolved and condensed under water, and carbonic oxide gas escapes : — 2(Ca2P03) + 2SiO, + C^o = 2CaSi03 + lOCO + P^. It is purified by melting under water containing sulphuric acid and red chromate of potassium. Properties. — Phosphorus is “a semitransparent, colorless, wax- like solid (in sticks or cakes), which emits white vapors when ex- posed to the air. Specific gravity 1.77. It is soft and flexible at common temperatures, melts at 110^, ignites in the air at a tempera- ture a little above its melting-point, burning wuth a luminous flame and producing dense Avhite fumes. Insoluble in water, but soluble in ether and in boiling oil of turpentine,” also in bisulphide of car- bon. It is,very poisonous. PHOSPHATES. 298 Granulated or pulverulent phosphorus is obtained by placing under equal parts of spirit and water in a bottle, standing the bottle in warm water till the phosphorus melts, then inserting the stopper (glass, not cork) and shaking the whole till cold. Red or Amorphous Phosphorus . — Ordinary phosphorus kept at a temperature of about 450® Fahr., in an atmosphere from which air is excluded, becomes red, opaque, insoluble in liquids in which ordi- nary phosphorus is soluble, oxidizes extremely slowly, and only ignites when heated to near 500° Fahr. It is used in the manufac- ture of several varieties of lucifer-matches, not emitting the poison- ous jaw-destroying fumes given by ordinary phosphorus. Quantivalence . — The atom of phosphorus is quinquivalent, as seen in the pentachloride (PCI5) and oxychloride (PCI3O) ; but it often exhibits tri valent activity, as seen in the trichloride {PCI3) and trihydride (PH3). Molecular Weight . — Phosphorus is an exception to the rule that the atomic weights (in grains, grammes, etc.) of elements occupy similar volumes of vapor at similar temperatures, the equivalent weight of phosphorus (31) only giving half such a volume. Hence while the molecular weights, that is, double the atomic weights, of oxygen (O 2 = 32), hydrogen (H 2 = 2), nitrogen (N 2 = 28), etc. give a similar bulk of vapor at any given temperature ; the double atomic weight of phosphorus (P 2 = G2) only gives half this bulk ; that is, four times the atomic weight of phosphorus must be taken to obtain the whole bulk. It would appear therefore that the molecule of phosphorus contains four atoms (P^ = 124). As with sulphur, however, phosphorus in the state ordinarily known to us may be abnormal, and a variety yet be found in which the molecular weight is double the atomic weight. Phosphoric Acid. The chief use of phosphorus in pharmacj^ is in the for- mation of Diluted Phosphoric Acid. Phosphorus is boiled with nitric acid and water until dissolved. The solution, evaporated to a low bulk to remove nitrous compounds, and rediluted so as to contain nearly^ 14 (13.8) per cent, of acid (H3POJ, equivalent to 10 per cent, of phosphoric an- hydride (P.2O5), constitutes the Acidum Phosphoricunt 'Di- lutum.^ B. P. and U. S. P., a colorless sour liquid of specific gravity 1.08 (1.05G U. S. P.). If the necessaiy appliances are at hand, four or five ounces of this acid may be pre- pared as follows : A quarter of a pint is made by boiling together, in a retort attached to a Liebig^s condenser, 103 grains of phosphorus, fluidounce of the official nitric acid, and 2 ounces of water. When about 1 oz. of water has distilled over, it should be returned to the retort, and the operation repeated until the phosphorus has disap- peared. 25 * 294 SALTS OF ACIDULOUS RADICALS. 3P4 + 20HNO3 + 8 H ,0 = I2H3PO, + 20 NO Phos- Nitric acid. Water. Phosphoric Nitric phorus. acid. oxide. The liquid remaining in the retort is then transferred to a dish (preferably of platinum), evaporated down to about half an ounce, and, lastly, diluted with distilled water to 5 fluidouncesJ The use of the water in this process is to moderate the reaction. Strong hot nitric acid oxidizes phosphorus with almost explosive rapidity, hence must not only be diluted in the first instance, but be rediluted, from time to time, to prevent its becoming too strong by loss of water. Deficiency of nitric acid must also be avoided, or^ some phosphorous acid (H.^PHOg) will be formed. A flask, in the neck of which a funnel is inserted, and a second funnel inverted, so i that its mouth rests within the mouth of the first, is an efficient and convenient arrangement of apparatus for this process, especially if the ope^i'ation be conducted slowly. Solution of phosphoric acid evaporated leaves a residue which melts at a low red heat, yielding pyrophosphorzc aczd, and, finally, metaphosphoric acid ( facial Phosphoric Acid). Quanhvalence. — The elements represented by the formula PO^ are those characteristic of phosphates. The grouping is trivalent ; hence there may exist trimetallic or normal phosphate (M'gPOJ, dimetallic acid phosphates (M'.^HPO^), monometallic acid phos- phates (M'H2P04), and, lastly, trihydric phosphate (HgPO^), or common phosphoric acid. These are the ordinary phosphates met with in nature or used in pharmacy ; the rarer pyrophosphates, metaphosphates, phosphites, and hypophosphites will be mentioned subsequently. Analytical Reactions ( Tests), First Analytical Reaction. — To an aqueous solution of a phosphate (e.g. add solution of sulphate of mag- nesium with which chloride of ammonium and ammonia have been mixed ; a white crystalline precipitate of ammo- nio-magnesium phosphate falls (MgAmPOJ. Chloride of ammonium is added to prevent the precipitation of hydrate of magnesium. Arseniates, from their close analogy to phosphates, give a similar precipitate with the magnesium reagent. Second Analytical Reaction To a neutral aqueous solu- tion of a phosphate add solution of nitrate of silver; light- yellow phosphate of silver (AggPOJ is precipitated. To a portion of the precipitate add ammonia ; it dissolves. To another portion add nitric acid ; it dissolves. By this reaction phosphates may be distinguished from their close allies the arseniates, arseniate of silver being of a chocolate color. PHOSPHATES. 295 Third Analytical Reaction. — a solution (in a few drops of acid) of a phosphate insoluble in water {e.g. Ca32POJ add an alkaline acetate (that is, a mixture of soda or ammonia with excess of acetic acid), and then a drop or two of solution of perchloride of iron ; yellowish-white ferric phosphate (Fe2POJ is precipitated. Too much of the ferric chloride must not be added, or ferric acetate will be produced, in which ferric phosphate is to some extent soluble. To remove the whole of the phosphoric radical from the solution, add ferric chloride so long as a precipitate is pro- duced, and then boil the mixture ; ferric phosphate and ferric oxyacetate are precipitated. To obtain confirmatory evidence of the presence of phos- phate in this precipitate, and to separate the phosphoric radical as a pure un mixed phosphate, collect the precipitate on a filter, wash, drop some solution of ammonia on it, then sulphydrate of ammonium, and finally wash with water; black ferrous sulphide remains on the filter, while phosphate of ammonium occurs in the filtrate. To the filtrate add a mixture of solutions of sulphate of magnesium and chlo- ride of ammonium, and well stir; ammonio-magnesian phosphate is precipitated. The above reaction is useful in the analysis of bone-earth, other earthy phosphates, phosphate of iron, and all phosphates insoluble in water. Only arseniates give similar appearance ; but the acid solu- tion of these may be decomposed by sulphuretted hydrogen (H^S), especially after agitation with sulphurous acid and subsequent ebul- lition. Other Analytical Reactions. — Solutions of barium and calcium salts give, with aqueous solutions of phosphates, white precipitates of the respective phosphates BaHPO^, or Bas^PO^, and CaHPO^, or Ca32PO^, all of which are soluble in acetic and the stronger acids. QUESTIONS AND EXERCISES. 562. State the source of phosphorus. 563. Give equations or diagrams explanatory of the isolation of phosphorus from its natural compounds. 564. What is the composition of farmers’ “ superphosphate,” and how prepared ? 565. Enuijierate the properties of ghqsphorus. 296 SALTS OF ACIDULOUS RADICALS. 566. Mention some solvents of phosphorus. 567. How is the official Diluted Phosphoric Acid made ? 568. Describe the precautions necessary to be observed in making this acid. 569. What is the strength of the official acid ? 570. AVrite formulae illustrative of all classes of orthophosphates. 571. Mention the chief tests for soluble and insoluble phosphates. 572. By what reactions may phosphates be distinguished from arseniates ? Vanadium^ Y, 51.3, is a very rare element, and is here mentioned only because of its exceedingly interesting rela- tionship to nitrogen, phosphorus, and arsenicuin. Discovered but not isolated by Sefstroin, and its compounds investi- gated by Berzelius, it has only recently been obtained in the free state and fully studied by Hoscoe. Oxides of Nitrogen. Orthophosphates Hg'PO^ Pyrophosphates H/P.p^ Metaphosphates K'POg Oxides of Vanadium vaaA.A03,va,VO Orthovanadates R/VO^ Pyrovanadates R/A^^O^ Metavanadates R'A^O, Isomorphous Minerals. Ajmtite 3 (Ca 32 POJ,CaFl 2 Pyromorphite 3 (Pb 32 POj,PbCl 2 Mimetesite 3 (Pb 32 AsOj,PbCl 2 Yanadinite 3 (Pb 32 YO^^,PbCl 2 BORACIC ACID AND OTHER BORATES. Formula of Boracic Acid H3BO3. Molecular weight 62. The composition of artificial boracic acid is expressed by the for- mula H3BO3 ; but at a temperature of 212^ F. this body loses the ele- ments of water and yields metaboracic acid, HBO2. ^J'he latter acid exists in the jets of steam (fumerolles or suffioni) that issue from the earth in some districts of Tuscany, and collects in the water of the lagoni (lagoons or little lakes) formed at the orifice of the steam- channel. This acid liquid evaporated by aid of the waste natural steam and neutralized by carbonateof sodium gives common borax (2NaB02, 2HB02,9H20), possibly an acid metaborate of sodium, with water of crystallization. It occurs ‘‘ in transparent colorless crystals, sometimes slightly effloresced, with a weak alkaline reaction ; in- soluble in rectified spirit, soluble in water.” Borax is also found native, particularly in Thibet. Fused borax readily dissolves metallic oxides, as will have been already noticed in testing for cobalt and BORATES. 297 manganese. Hence, besides its use in medicine [Sodii Boras, U. S. P. ; Borax ; Mel Boracis, B. P., or Mel Sodii Boratis, U. S. P., and Glycerinum Boracis, B. P.) , it is employed as a flux in refining and other metallurgic and ceramic operations. Qaantivalence. — The boracic radical is trivalent (BO3'"), the metaboracic, univalent (BO^') ; they have not been isolated. The element boron, like carbon, occurs in the amorphous, graphitoidal, and crystalline conditions. It is a trivalent element (B'"), yielding definite salts, such as the chloride (BCI3) and fluoride (BF3). Its atomic weight is 11. Heactions. First Synthetical Reaction, — To a hot solution of a crys- tal of borax add a few drops of sulphuric acid and set aside; on cooling, cr^’stalline scales of boracic acid (H 3 BO 3 ) are deposited. They may be purified by collecting on a filter, slightly washing, drying, digesting in hot alcohol, filtering, and setting aside ; pure boracic acid (B. P.) is deposited. The acid may also be recrystallized from w.ater. Fifty^ grains dissolved in one ounce of rectified spirit con- stitutes “ Solution of Boracic Acid,’^ B. P. When heated, these crystals lose water and yield, first, metaboracic acid (HBO2), and, subsequently, when fused, boracic anhydride (B2O3). Boracic acid is very weak. It only slowly decomposes carbonates, and resembles alkaline compounds in coloring turmeric brown. In- deed the alkalinity of borax is as great as if it contained no acidu- lous radical whatever. Second Synthetical Reaction, — Mix together 1 part of boracic acid, 4 of acid tartrate of potassium, and 10 or 20 of water; evaporate to a syrupy consistence, spread on plates, and set aside for dry scales to form. The resulting substance is, in water, far more readily soluble than either of its constituents, and is known as horo-tartrate of potas- sium,^ soluble tartar,^ or soluble cream o f tartar. The Prus- sian tartarus boraxatis dififers from the foregoing French variety in containing 1 part of borax to 3 of acid tartrate of potassium. Analytical Reactions ( Tests). First Anahjtical Reaction, — Dip a piece of turmeric paper (paper soaked in tincture of turmeric tubers and dried) into a solution of boracic acid ; it is colored brown-red, as by alkalies. The usual way of applying this test is as follows: Add to any borate a few drops of hydrochloric acid, immerse half of a slip of 298 SALTS OF ACIDULOUS RADICALS. turmeric paper in the liquid, then remove the hydrochloric acid by drying the paper over a flame. Concentrated hydrochloric acid and ferric chloride produce a somewhat similar effect. Second Analytical Reaction, — To a fragment of a borate or metaborate (borax, for example) in a small dish or watch- glass add a drop of sulphuric acid and then a little alcohol, warm the mixture and set light to the spirit; the resulting flame will be tinged of a greenish color at its edges by the volatilized boracic acid or boracic anhydride. The liquid should be well stirred while burning. Salts of copper and some metallic chlorides produce a somewhat similar color. Other Analytical Reactions. — In solutions of borax, barium salts give a white precipitate of barium metaborate (Ba2B02) s^^lwble in acids and alkaline salts. Nitrate of silver gives metaborate of silver (AgBO.^) soluble in nitric acid and in ammonia. Chloride of calcium, if the solution is not too dilute, gives white borate of calcium. QUESTIONS AND EXERCISES. 573. Illustrate the relation of vanadium to nitrogen by formulae of compounds of each element. 574. Describe the preparation of borax. 575. Give the formulae of boracic acid, metaboracic acid, and borax. 576. Mention the tests for borates or metaborates. The foregoing acids and other salts contain the only acidulous radicals that are commonly met with in analysis or in ordinary pharmaceutical operations. There are, hoioever, many others which occasionally present themselves. The chief of these will now he shortly noticed ; they are arranged in alphabetical order to facilitate reference. SALTS OF RARER ACIDULOUS RADICALS. Benzoic Acid (HC^H^O^) and other Benzoates. — Slowdy heat a fragment of benzoin (Beiizoinuni, B. P. and U. S. P.) in a test-tube; benzoic acid {Acidum Benzoicum^ B. P. and U. S. P.) rises in vapor and condenses in small, wdiite, feathery plates and needles, on the cool sides of the tube. If the benzoin is first mixed with twice its weight of sand or roughly powdered pumice-stone, and the heat very BENZOATES. 299 cautiously applied, the product will be less likely to be burnt, and a larger quantity be obtained. A more economical process is to boil the benzoin with one-fourth its weight of lime, filter, concentrate, decompose the solution of benzoate of calcium by hydrochloric acid, collect the precipitated benzoic acid, press between paper, dry, and sublime in a tube or other vessel. 2HC,H,0, + Ca2HO Ca2C,H,0, + 2H,0 Benzoic acid Hydrate of Benzoate of Water. (impure). calcium. calcium, Ca2C,II,0, + 2HC1 = CaCl, + 2 HC,H 503 Benzoate of Hydrochloric Chloride of Benzoic acid calcium. acid. calcium, (pure). Benzoic acid is also prepared on a large scale artificially from naphthalin, one of the crystalline by-products in the distillation of coal for gas. The naphthalin is oxidized by nitric acid to naphthalic or phthalic acid : — O.oHi, + 40, = Naphthalin. Oxygen. Phthalic acid. Oxalic acid. The phthalic acid is neutralized by lime and the phthalate of cal- cium heated with hydrate of calcium in a covered vessel at a tem- perature of about 640^ for several hours. Benzoate and carbonate of calcium are formed, and from the powder benzoic acid set free by action of hydrochloric acid. 2Ca08H,0, 4- Ca2HO = Ca2C,H,02 -f 2CaCO., Phthalate of Hydrate of Benzoate of Carbonate of calcium. calcium. calcium. calcium. The crystalline deposit formed when essential oil of almonds (hydride of benzoyl or benzoic aldehyd) is exposed to the air is ben- zoic acid. 2 C,H 50 H + 0, = 20 ,H 50 HO or 2HC,H,0, Hydride of Oxygen. Hydrate of Benzoic benzoyl. benzoyl. acid. There' is always associated with the product a minute quantity of a volatile oil of agreeable odor, suggesting that of hay. Benzoate of Ammonium . — To a little benzoic acid add a few drops of solution of ammonia ; it readily dissolves, forming benzoate of ammonium {Ammonii Benzoas^ U. S. P.) (NH,C,H,0,). HC.H^O, + NIT,HO = NH^C,H,0, + H,0 Benzoic acid. Ammonia. Benzoate of Water. ammonium. On evaporation, acid crystals or, ammonia being added, neutral crystals of benzoate of ammonium are deposited. Propertiei ^. — Benzoic acid is also soluble in other alkaline liquids, forming benzoates. It is slightly soluble in cold 300 SALTS OF ACIDULOUS RADICALS. water, more so in hot, and readily soluble in rectified spirit. It melts at 248° F., and boils at 462°, evaporating with only a slight residue. Tests , — The following are the tests for benzoic acid : To a portion of the above solution of benzoate of ammonium add a drop or two of sulphuric or hydrochloric acid ; a white crystalline precipitate of benzoic acid separates. To another portion, carefully made neutral, add a dro[) or two of neutral solution of perchloride of iron ; reddish ferric benzoate is precipitated. Benzoic acid is distinguished from an allied body, cinnamic acid (occurring in Balsams of Peru, Tolu, and Storax), bj" not yielding hydride of benzoyl (C^H^OH) (oil of bitter almonds) when distilled with chromic acid — that is, with a mixture of red chromate of potassium and sulphuric acid. Carminic Acid — This is the coloring principle of cochi- neal [Coccus, B. P. and U. S. P.). The carmine oi trade, when unadulterated [vide Pharmaceutical Journal, 1859-60, p. 546), is carminic acid united with about five per cent, of alumina, or occa- sionally, of oxide of tin or albumen. It should be wholly soluble in solution of ammonia. Carmine, with French chalk, or starch, con- stitutes face-rouge or animal rouge. Merrick tests the relative value of several samples of cochineal or carmine by observing how much solution of permanganate of potas- sium is required to change the color of a decoction to faint pink. Oetraric Acid (H^C^^H^oCig) is the bitter principle of Iceland moss [Cetraria, B. jP. and U. S. P.). In the lichen it is associated) with much starch. j Chrysophanic Acid (CjoHj^Og?). — This acid is the chief coloring- i matter of various species of rhubarb root [Rhei Radix, B. P., Rheum, v U. S. P.) and parmelia. It may be obtained in crystals of a golden- f yellow color, hence the name (from chrusos, gold, and |i phaind, I shine). Its synonyms are Rhaponticin, Rheic acid,\} Rhein, Rheumin, Rheuharharic acid, Rheuharharin, R^imicin.i^ Chrysophanic acid, black, red-brown, and red resins [Aporetine,'^ Phceoretine, and Erythroretine), a bitter principle, and tannic acid ' are considered to be the conjoint source of the therapeutic properties i of rhubarb. i Cyanic Acid (IlCyO) and other Cyanates. — The vain- i able reducing-power of cyanide of potassium (KCy) (or i ferrocyanide, K^Fcy) on metallic compounds is due to the I avidity with which cyanate (KCyO) is formed. Process . — Fuse a few grains of cyanide of potassium in a small jiorcelain crucible, and add powdered oxide of lead ; i a globule of metallic lead is at once set free, excess of the oxide converting the whole of the cyanide of potassium into cyanate of potassium. HIPPUR AXES. 301 Urea . — Cyanate of potassium (KCNO), or, better, cyanate of lead (Pb2CNO), treated with sulphate of ammonium, yields cyanate of ammonium (NH^ONO) ; and solution of cyanate of ammonium, when simply heated, changes to artificial urea (CH^N 20 ), the most important constituent of urine, and the chief form in which the nitro- gen of food is eliminated from the animal system. The process will be more fully described subsequently in connection with urea. Formic Acid (HCHO 2 ). — The red ant [Formica rufa) and several other insects, when irritated, eject a strongly acid, acrid liquid, hav- ing a composition expressed by the above formula, and which has appropriately received the name of formic acid ; it is also contained in the leaves of the stinging-nettle. Process , — It may be artificially prepared by heating equal weights of oxalic acid and gl^^cerine to a temperature of from 212*^ to 220^ for fifteen hours. The glycerine has, apparently, no chemical action, but, for some unknown reason, induces decomposition of the oxalic acid at a lower temperature than would otherwise be necessary ; at a higher temperature the formic acid itself is decomposed. On dis- tilling the mixture with water, the formic acid slowly passes over. The dilute acid may be concentrated by neutralizing with carbonate of lead, filtering, evaporating to a small bulk, collecting the deposited crystalline formate of lead, drying, decomposing in a current of sulphuretted hydro- gen, and separating the resulting syrupy acid, or distilling the formate of lead with strong sulphuric acid. = HCHO2 + CO, Oxalic Formic Carbonic acid. acid. acid gas. Formic acid may be instructively though not economically pre- pared by the oxidation of methylic alcohol (wood-spirit), just as acetic acid and valerianic acid are obtained from ethylic alcohol and amylic alcohol respectively. CH3HO 4 - O2 = HCHO2 + H2O Wood Oxygen. Formic Water, spirit. acid. Tests . — Formic acid does not char when heated alone or with sul- phuric acid, but splits up into carbonic oxide gas and water. It is recognized by this property and by its reducing-action on salts of gold, platinum, mercury, and silver. It is solid below 32^. Gallic Acid. — See Tannic Acid, Hemidesmic Acid. — The supposed active principle of hemidesmus root {Hemidesmi Radix^ B. P.). Hippuric Acid (HCgHgNOg) is a constituent of human urine (much increased on taking benzoic acid), but is best prepared from the urine of the horse (hence the name, from hippos, a horse), or, better, from that of the cow. To such urine add a little milk of 26 302 SALTS OF RARER ACIDULOUS RADICALS. lime, boil for a few minutes, remove precipitated phosphates by filtra- tion, drop in hydrochloric acid until the liquid, after well stirring, is exactly neutral to test-paper, concentrate to about one-eighth the original bulk, and add excess of strong hydrochloric acid ; impure hippuric acid is deposited. From a solution of the impure acid in hot water chlorine gas removes the color, and the liquid deposits crystals of pure hippuric acid on cooling. Its constitution is that of henzoic glycocine, C.^H 2 (C 7 H 50 ) (NH 2 ) 02 . Tests. — To a solution of hippurate add neutral solution of ferric chloride; a brown precipitate (ferric hippurate) results. Salts of silver and mercury give white precipitates. Heat hippuric acid in a test-tube ; it chars, benzoic acid sublimes, and vapors of characteristic odor are evolved; they contain, amongst other bodies, hydrocyanic acid and a substance smelling somewhat like Tonka bean. The crystalline form of hippuric acid is characteristic ; it will be described in connection with the subject of urine. QUESTIONS AND EXERCISES. 577. Give the preparation, composition, properties, and tests of benzoic acid, employing equations or diagrams. 578. What is the nature of carmine ? 579. Name the bitter principle of Iceland moss. 580. Mention the coloring principle of rhubarb. 581. To what is rhubarb considered to owe its medicinal activity ? 582. How is cyanate of potassium prepared, how converted into an ammonium salt, and what the relations of the latter to urea ? 583. Give the formulae of cyanic acid, cyanate of ammonium, and urea. 584. What is the chemical formula of formic acid ? 585. Describe the artificial production of formic acid. 586. Describe the relation of formic acid to wood-spirit. 587. State the sources, characters, and tests of hippuric acid. Hydroferrocyanic Acid (H^Fe"Cy6, H^Fcy"") and other Ferrocyanides. — The ferrocyanide of most interest is that of potas- sium [Potassii Ferrocyanidum, U. S. P.), the yellow prussiate of potash [Potassce Prussias Flava, B. P.) (K^FeCgNg, SH.^O), the formation of which was alluded to in connection with hydrocyanic acid (see page 248). It cannot be regarded as simply a double salt of cyanide of potassium with cyanide of iron (FeCy 2 , 4KCy), its chemical properties being entirely different from either of those sub- stances; moreover, unlike cyanide of potassium, it is not poisonous. Most of its reactions point to the conclusion that its iron and cyano- gen are intimately united to form a definite quadrivalent radical ap- propriately termed ferrocyanogen (FeCyg, or Fey). One part of ferrocyanide of potassium in 20 of water forms the official “Solution of Yellow Prussiate of Potash,” B. P. | FERRIDCYANIDES. 303 Tests. — Many of the ferrocj^anides are insoluble, and are therefore precipitated when solution of ferrocyanide of potassium is added to the various salts. Those of iron and copper, being of characteristic color, are adopted as tests of the presence of the metals or of the ferrocyanogen, as the case may be. 3K,Fcy -f 2(Fe,3SOJ = Fe.Fcyg + 6K,SO,. To solution of ferroG3'anide of potassium add a ferric salt; ferrocyanide of iron (Fe^Fcy3) (Fi’ussian Blue) {Ferri ferro- cyanidum.^ U. S. P.) is precipitated. To another portion add solution of a copper salt ; red- dish-brown ferrocyanide of copper (Cu^Fcy) is precipitated. Note. — The ferrocyanogen in ferrocyanide of potassium is broken up when the salt is heated with sulphuric acid, carbonic oxide being evolved if the acid is strong, and hydrocyanic acid if weak : — K^FeCfiNs + m,0 + GH^SO, = 2K,SO^ + FeSO, -f 3(NHJ,SO, -f 6CO. 2K,FeCy6 + hH^SO, + xH,0 = FeK.FeCyg + 6KHSO, -f 6HCy X xHaO. Hydrocyanic Acid has already been described. ( Vide p. 249.) Carbonic oxide (CO). — Heat two or three fragments of ferrocya- nide of potassium with eight or ten times their weight of sulphuric acid, and, as soon as the gas begins to be evolved, remove the test- tube from the flame ; for the action, when once set up, proceeds some- what tumultuously. Ignite the carbonic oxide at the mouth of the tube ; it burns with a pale blue flame, the product of combustion being carbonic acid gas (CO^). Carbonic oxide is a direct poison. It is generated whenever coke, charcoal, or coal burns with an insufficient supply of air. Hence the danger of open fires in the more or less closed apartments of ordinary dwellings. Carbonic oxide may also be obtained from oxalic acid. ( Vide p. 283.) Hydroferridcyanic Acid (ngFe"'2C^y^29 H^gFdcy^^) AND OTHER Ferridcyanides — Pass clilorinc gas slowly through solution of ferroc^'anide of potassium until the liquid, after frequent shaking, ceases to give a blue precipi- tate, when a minute portion is taken out on the end of a glass rod and brought into contact with a drop of a dilute solution of a ferric salt ; it now contains ferridcyanide of potassium (K6Fe'"2^yj,2, or K^gFdcy^^), red prussiate of potash (B. P.), as it is termed from the color of its crystals. Excess of chlorine must be carefully avoided, as chloride of cyanogen and other compounds are then formed. 2K',Fe"Cy'g + Cl'^ = 2K'CP + K'gFe'^^Cy'.a- 304 SALTS OF RARER ACIDULOUS RADICALS. Note. — The removal of two atoms of potassium from theferrocya- nide is the only change of composition that occurs ; but the ferrocya- nogen is altered in quality, its iron passing from the ferrous to the ferric condition, from bivalent to trivalent activity, a condition in which it no longer precipitates ferric salts, but, on the other hand, gives a dark-blue precipitate with ferrous salts. The radical is dis- tinguished as ferridcyanogen. Ferridcyanide of potassium may also be prepared by a modifica- tion of the foregoing method in which nascent instead of free chlorine is employed (Wenzell). Take of Bichromate of Potash 1 part, Fer- rocyanide of Potassium Cryst. 5.72 parts. Hydrochloric Acid, of spec. grav. 1.16, 3 parts, by weight. Water 60 parts. Dissolve the two salts in hot water, add the acid, heat to boiling, continuing the ebullition, replacing the water evaporated during *the process until a portion of the filtered liquid is not precipitated on the addition of sesquichloride of iron. When reaction is completed, filter the liquid, and wash the hydrate of chromium, unite the liquids, and concentrate to crystallization. If the evaporated liquid possess an acid reaction, the addition of caustic potash, in sufficient quantity to cause a weak alkaline reaction, will greatly facilitate the subsequent crystalli- zation. 6(K,FeCye) + K,Cr,0, + 8HC1 = 3(K,Fe,Cy,,) . + 8KC1 + H,0 + Cr,6HO. Test, — To a portion of the solution add solution of ferrous sulphate ; a precipitate falls. This precipitate is ferridcyanide of iron (TurnbulPs blue), Fe^sFe^'^Cy^^? or re''3Fdcy^h KgFdcy + 3FeSO^ = FegPdcy 4- 3K^SO^. It will be noticed that the change in the condition of the iron keeps up the balance of the atomic values of the various parts of the radicals or of the salts ; the quantivalential equilibrium is maintained. A solution of 1 of ferridcyanide of potassium in 20 of water con- stitutes the “Solution of Ked Prussiate of Potash,’’ B. P. Hydrofluoric Acid (HF) and Other Fluorides. — Molecular weight of HF, 20. The chief use of hydrofluoric acid is in the etching on glass. The operation, pertormed on the small scale, also constitutes the best test for fluorine, the elementary radical of all fluorides. Process and Test, — Warm any odd piece of window- glass, having an inch or two of surface, until a piece of beeswax rubbed on one side yields a thin oilj^ film. Wlien cool make a cross, letter, or other mark on the glass by pressing a pointed piece of wood, a‘ penknife, or file, through the wax. Place a few grains of powdered fluor spar, the commonest natural fluoride, in a porcelain crucible (or a lead cup), add a drop or two of sulphuric acid, cover HYPOPHOSPHOROUS ACID. 305 the crucible with the prepared glass, waxed side down- wards, and gently warm the bottom of the crucible in a fume-chamber or in the open air, in such a way as not to melt the wax. After a few minutes remove the glass, wash the waxed side by pouring water over it, scrape off most of the wax, then warm the glass^ and wipe off the remainder ; the marks made through the wax will be found to be per- manently etched on the glass; the acid has eaten into or etched (ft’om the German dtzen^ to corrode) the glass. In the above operation the fluoride of calcium and sulphuric acid yield hydrofluoric acid, thus : — -CaF 2 + H^SO, = CaSO, + 2HF. The hydrofluoric acid gas and the silica of the glass then yield gaseous fluoride of silicon (SiF^), which escapes, and water, thus : — 4HF + SiO^ = 2 H 2 O -F SiF^. The silica being removed from the glass, leaves furrows or etched portions. Note. — In the experiment just described, the liberated hydrofluoric acid also attacks the siliceous glazing of the porcelain crucible ; so that in important cases, where search is made for very small quanti- ties of fluorine, vessels of platinum or lead must be employed. Uses. — The aqueous solution of hydrofluoric acid used by etchers, and commonly termed simply hydrofluoric acid, or fluoric acid, is prepared in leaden stills and receivers, and kept in leaden or gutta- percha bottles. Except these materials, as well as platinum and fluor spar, hydrofluoric acid rapidly attacks any substance of which bottles and basins are usually made. It quickly cauterizes the skin, producing a painful slow-healing sore. Quantivalence. — The atom of fluorine, like that of chlorine, bro- mine, or iodine, is univalent (F'). The great analogy existing be- tween these radicals extends to their compounds. Fluorine is said to be a colorless gas ; but, from the avidity with which it combines with all elements (except oxygen), it is so difficult of isolation as hitherto to preclude satisfactory study of its physical properties. Hypophosphorous Acid (HaPO.^, or HPH2O2) and other Hypophosphites. — Boil together, in a fume-chamber, a grain or two of phosphorus, a few grains of slaked lime, and about a quarter of an ounce of water until phospho- retted hydrogen, a spontaneously inflammable, badly smell- ing gas, ceases to be evolved. The mixture. Altered, yields solution of hypophosphite of calcium (Ca2PHaO Pg _F 6 H ,0 + SCaH^Oa = 3(Ca2PH20,) + 2 PH 3 . The solution, when concentrated by evaporation, has been known to explode, probably from formation of phosphoretted hydrogen. 2G* 306 SALTS OF RARER ACIDULOUS RADICALS. This may be prevented, it is said, by evaporating at a low tempera- ture, especially towards the close of the operation ; or by adding alcohol, which decomposes any traces of liquid phosphoretted hydro- gen (PH,) or solid phosphoretted hydrogen (P 2 H) which possibly may be present, and to which it is conceivable explosion may be due. Phosphoretted hydrogen (PH3). — The above reaction is also that by which phosphoretted hydrogen, the third hydride of phosphorus, may be prepared. If the gas is to be collected, the phosphorus and water may first be boiled in a flask until spontaneously a jet of phos- phorus vapor escapes, with steam, from the end of the attached de- livery-tube. Strong solution of caustic potash or soda is next very gradually poured into the flask through a funnel tube previously fitted into the cork, the liquid being kept boiling. Phosphoretted hydro- gen is then evolved, and if the delivery-tube dip under water may be collected, or allowed to slowly pass up through the water bubble by bubble so as to form the peculiar rings of smoke (phosphoric anhy- dride) characteristic of the experiment. Hypoyhosphite of calcium may be obtained in crystals [Calcii Hypophosphis, U. S. P.) ; but the solution is usually at once evapo- rated to dryness, a white pulverulent salt being obtained. The hypophosphites of Potassium and Sodium [Potassii Hypophosphis^ U. S. P., and Sodii Hypophosphis, U. S. P.) may be obtained in the same way from their hydrates, and many other hypophosphites simi- larly from other hydrates, or by double decomposition of the calcium salt and carbonates. Hypophosphorous acid, the hydrogen hypo- ; phosphite, may be prepared by decomposing the barium salt with I sulphuric acid or the calcium salt by oxalic acid ; hypophosphite of quinine by dissolving the alkaloid in hypophosphorous acid, or by decomposing sulphate of quinine by hypophosphite of barium. Hypo- phosphite of Iron [Ferri Hypophosphis, U. S. P.) may be obtained by dissolving ferric hydrate in cold aqueous hypophosphorous acid and evaporating the solution. The hypophosphites are often used in j medicine in the form of syrups. The term hypophosphite is in allu- ■ sion to the smaller amount [vrco, hupo, under or deficiency) of oxygen i in these compounds (R'3P02) than in the phosphites (R3PO3), a class I of salts having again less oxygen in their molecules than exists in ! those of the phosphates (R3POJ. The prefix has similar signi- j ficance in such words as hyposulphite and hypochlorite. I Tests. — To a portion of the above solution af hy^poplios- I pliite of calcium add solution of chloride of barium, clilo- i ride of calcium, or acetate of lead ; in neither case is a i precipitate obtained, whereas soluble phosphates and phos- phites yield white precipitates of phosphate or phosphite • of barium, calcium, or lead. To other portions add solu- : tions of nitrate of silver and mercuric chloride ; the resi)ec- tive metals are precipitated as by phosphites. To another small j^ortion add zinc and dilute sulphuric acid ; hydrogen and phosphoretted hydrogen are evolved as from phosphites. ; To another portion add sufficient oxalic acid to remove the calcium; filter; to the solution of hypophosphorous acid HYPOSULPHUROUS ACID. SOY add solution of sulphate of copper and slowly warm the mixture ; solid brown hydrate of copper is precipitated : increase the heat to the boiling-point; hydrogen is evolved and metallic copper set free. Heat a small quantity of a solid hypophosphite on the end of a spatula in a flame ; it splits up into pyrophosphate, phosphoretted hydrogen, and water, burning with a phosphorescent light. 2(Ca2PH,0,) = Ca,P,0, -f 2 PH 3 +H,0. Hyposulphurous Acid (H^S^Og) and other Hyposul- phites. — The only hyposulphite of much interest in phar- macy is the sodium salt (Hyposulphite of Soda, B. P., Sodii Eyposulphis, H. S. P.) (Na^S.Pg, bUfi). Process. — Heat together gentljq or set aside in a warm place, a mixture of solution of sulphite of sodium (Na.^SOg), and a little powdered sulphur; combination slowly takes place, and hyposulphite of sodium is formed. The solu- tion, Altered from excess of sulphur, readily yields crystals. [The solution.of sulphite of sodium may be made by satu- rating a solution of soda with sulphurous acid gas.] Use of hyposulphite of sodium in quantitative analysis . — In the British Pharmacopoeia hyposuli)hite of sodium is given as a reagent for the quantitative estimation of free iodine in volumetric analysis. To a few drops of iodine- water add cold mucilage of starch; a deep-blue color (starch iodide) is produced. To the product add solution of hyposulphite of sodium until the blue color just disap- pears. This absorption of iodine is sufliciently deflnite and delicate to admit of application for quantitative purposes. II depends on the combination of the iodine with half of the sodium in two molecules of the hyposulphite, the hy^osul- phurous radicals of the two molecules apparently coalescing to form a new radical, the tetrathionic (from rirpa?, tetras^ four, and theion.^ sulphur), tetrathionate (Na^S^O,.) and iodide of sodium being formed. Sulphur Oxyacids . — It will be as well here to give the formulae of other oxyacids of sulphur, forming with the four already mentioned a series that is as useful as the series of compounds of nitrogen and oxygen in illustrating the soundness of Dalton’s atomic theory (p. 43). Hydrosulphurous Acid . . . . . . H,SO, Sulphurous Acid . . . H.SOg Sulphuric Acid . . . H,SO, Hyposulphurous Acid . . . . . . H.S^O, Dithionic Acid . . . TI.,S,Og Trithionic Acid Tetrathionic Acid Pentathionic Acid ■ . . 308 SALTS OF RARER ACIDULOUS RADICALS. Use of Hypo'^^ in Photography , — The sodium hyposul- phite is largelj" used in photography to dissolve chloride, bromide, or iodide of silver off plates which have been ex- posed in the camera. Prepare a little chloride of silver by adding a chloride (chloride of sodium) to a few drops of solution of nitrate of silver. Collect the precipitated chlo- ride on a filter, wash, and add a few drops of solution of hyposulphite of sodium; the silver salt is dissolved, solu- tion of double hyposulphite of sodium and silver being formed. The solution of this double hyposulphite has a remarkabl}^ sweet taste, sweeter than syrup. The double hyposulphite of sodium and gold is employed for giving a pleasant tint to photographic prints. Test , — To solution of a hyposulphite add a few drops of dilute sulphuric or other acid ; hyposulphurous acid is set free, but at once begins to decompose into sulphurous acid, recognized by its odor, and free sulphur ( 2 H.^S^ 03 = 2 H 2 SO 3 + S 2 ). This reaction constitutes the best test for hyposulphites. Another good test of a soluble simple hyposulphite is its power of dissolving chloride of silver with production of a sweet solution. QUESTIONS AND EXERCISES. 588. Give the formula of ferrocyanide of potassium. 589. What is the supposed constitution of ferrocyanide of potas- sium ? 590. Enumerate the tests for ferrocyanogen. 591. What are the respective reactions of ferrocyanide of potas- sium with strong and weak sulphuric acid ? 592. Mention and explain a common source of carbonic oxide in households ? 593. Write equations or diagrams illustrative of the changes effected on ferrocyanide of potassium during its conversion into fer- ridcyanide. 594. By what reactions may the presence of a ferridcyanide in a solution be demonstrated ? 595. State the difference between Prussian blue and Turnbull’s blue. 596. Describe the source, mode of preparation, chief use of, and test for hydrofluoric acid. 597. Illustrate by a diagram the preparation and composition of hyposulphite of sodium. 598. Mention the uses and characteristic reactions of hyposulphite of sodium. 599. Give the names and formuhe of eight acids, each containing hydrogen, sulphur, and oxygen. LACTATES. 309 Lactic Acid (HgCaH^Og) and other Lactates. — When milk turns sour its sugar has become converted into an acid appropriately termed lactic (Zac, lactis). Other saccharine and amylaceous sub- stances also by fermentation yield lactic acid. Neither the hydrogen lactate (lactic acid) nor other lactates are much used in England, but the former is official in America [Acidum Lacticum, U. S. P.). Process, — Lactate of calcium and lactic acid may be pre- pared as follows : Mix together eight parts of sugar, one of common cheese, three of chalk, and fifty of water, and set aside in a warm place (about 80° F.) for two or three weeks ; a mass of small crystals of lactate of calcium re- sults. Kemove these, recrystallize from hot water, decom- pose by sulphuric acid, avoiding excess, digest in alcohol, filter off the sulphate of calcium, evaporate the clear solu- tion to a syrup ; this residue is lactic acid ; sp. gr. 1.2 12. Lactate of Iron {Ferri Lactas,^ U. S. P.) is made by di- gesting iron filings in warm diluted lactic acid (1 acid to 16 water) till effervescence of hydrogen ceases, filtering and setting aside to cool and crystallize. The crystals are col- lected, washed with alcohol, and dried. This ferrous lac- tate occurs in greenish-white crystalline crusts or grains, of a mild, sweetish, ferruginous taste, soluble in forty-eight parts of cold, and twelve of boiling water, but insoluble in alcohol. Exposed to heat it froths up, gives out thick, white, acid fumes, and becomes black ; sesquioxide of iron being left. If it be boiled for fifteen minutes with nitric acid of the specific gravity 1.20, a white, granular deposit of mucic acid will occur on the cooling of the liquid. Test. — No single reaction of lactic acid is sufficiently distinctive to form a test. The crystalline form of the lactate of calcium, as seen by the microscope, is charac- teristic. The production of this salt, and the isolation of the syrupy acid itself, are the only means, short of quanti- tative analysis, on which reliance can be placed. A variety of lactic acid has been obtained from the juice of fish ; it is termed sarcolactic acid (from od/jl, gen. aapxoj, flesh). Malic Acid (1130^11305) and other Malates (from malum^ an apple). — The juice of unripe apples, goose- berries, currants, rhubarb stalks, etc., contains malic acid and malate of potassium. When isolated it occurs in deliquescent prismatic crystals. Tests. — Malate of calcium (CaHC^H305) is soluble in water ; hence the aqueous solution of malic acid or other malate is not precipitated by lime-water or chloride of cal- 310 SALTS OF RARER ACIDULOUS RADICALS. cium ; but on adding spirit of wine a white precipitate falls, owing to the insolubility of the calcium malate in alcohol. Malates are precipitated by lead-salts; on warming the malate of lead with acetic acid it dissolves, separating out in acicular crystals on cooling. If the mixture be heated without acid the malate of lead agglutinates and fuses. Hot strong sulphuric acid chars malic acid far less readily than it does nearly all other organic acids. Malic acid is one of the chief products of the action of nitrous acid on asparagin ( 04118^.^03, ^ crystalline body extracted from asparagus and marshmallow [Althea, XJ. S. P.). Meconic Acid (H3C-HO7). Opium contains meconic acid (from mekon^ a poppy) partially combined with morphia. To concentrated infusion of opium, nearly neu- tralized by ammonia, add solution of chloride of calcium, meconate of calcium is precipitated. Wash the precipitate, place it in a small quantity of hot water, and add a little hydrochloric acid ; the clear liquid (filtered, if necessary) deposits scales of meconic acid on cooling. Test — To solution of meconic acid or other meconate, or to infusion of opium, add a neutral solution of ferric chloride ; a red solution of meconate of iron is produced. | To a portion of the mixture add solution of corrosive sub- limate; the color is not destroyed; to another portion add hydrochloric acid; the color is discharged. (These reagents act on sulphocyanate of iron, which is of similar tint, in exactly the opposite manner.) The normal mecoiiates of potassium, sodium, and ammonium are soluble in water, the acid meconates very slightly soluble, the meco- nates of barium, calcium, lead, copper, and silver insoluble in water but soluble in acetic acid. Metaphosphoric Acid (HPO3) and other Metaphos- phates. — Prepare phosphoric anhydride (P2O5) by burning a small piece of phosphorus in a porcelain crucible placed on a plate and covered by an inverted test-glass, tumbler, half-pint measure-glass, or some such vessel. After wait- ! ing a few minutes for the phosphoric anhydride to fall, i pour a little water on the plate and filter the liquid ; the product is solution of metaphosphoric acid (from ^tra, 1 meta^ a preposition denoting change). P, 0 , -f H ,0 = 2HPO3. Tests , — To solution of metaphosphoric acid add ammo- nio-nitrate of silver, or to a neutral raetaphosphate add NITRITES. 811 solution of nitrate of silver ; a white precipitate (AgPOg) is obtained. This reaction sufficiently distinguishes meta- phosphates from the ordinary phosphates or orthophos- phates (from 6 p 06 ? orthos^ straight), as the common phos- phates may, for distinction, be termed (which give, it will be remembered, a yellow precipitate with nitrate of silver). Another variety of phosphates shortly to be considered, the pyrophosphates, also give a white precipitate with nitrate of silver. To the solution of metaphosphoric acid obtained as above or by the action of acetic acid on a metaphosphate, add an aqueous solution of white of egg ; coagulation of the albumen ensues. Neither orthophos- phoric nor pyrophosphoric acid coagulates albumen. Boil the aqueous solution of metaphosphoric acid for some time ; on testing the solution the acid will be found to have been converted into orthophosphoric acid : HPO3 -f H,0 = H3PO,. The ordinary medicinal phosphoric acid is made from phosphorus and nitric acid, the liquid being evaporated to a syrupy consistence to remove the last traces of nitric acid. It may contain pyrophosphoric and metaphosphoric acids, if the heat employed be high enough to remove the elements of water: — JE^O, — H ,0 = HPO3. On redilution the metaphosphoric acid only slowly reab- sorbs water. If, therefore, on testing, metaphosphoric be found to be present, the solution should be boiled until conversion to orthophosphoric acid has occurred. Nitrous Acid (HNOJ and other Nitrites — Strongly heat a fragment of nitrate of potassium or of sodium on a piece of platinum foil ; oxygen is evolved and nitrite of potassium remains. Test, — Dissolve the residue in water, add a few drops of dilute sulphuric acid, then a little weak solution of iodide of potassium, and, lastly, some mucilage of starch ; the deep-blue compound of iodine and starch is at once pro- duced. Repeat this experiment, using nitrate of potassium instead of nitrite ; no blue color is produced. 2 HI + 2HNO3 = 2 H ,0 + 2 NO + I,. Test for Nitrites in Water. — This liberation of iodine by nitrites and not by nitrates is a reaction of considerable value in searching for nitrites in ordinary drinking-waters, the occurrence of such salts 312 SALTS OF RARER ACIDULOUS RADICALS. being held to indicate the presence of nitrogenous organic matter in a state of oxidation or decay. The sulphuric acid used in the ope- ration must be pure, and the iodide of potassium free from iodate. Commercial Nitrous Acid. — The liquid commonly termed in pharmacy nitrous acid is simply nitric acid impure from the presence of nitrous acid. The only nitrite used in medicine is a nitrite of an organic basy- lous radical, ethyl; nitrite of ethyl (C2H5NO2), or nitrous ether, is the chief constituent of “ sioeet spirit of nitre'' [S'piritus JStheris Nitrosi, B. P. and U. S. P. : vide Index). Phosphorous Acid (H3PO3, or H2PIIO3). — It is necessary to notice this compound in order that the reader may have brought before him the three acids of phosphorus, namely, phosphoric acid (H3PO4), phosphorous acid (H2PIIO3), and hypophosphorous acid (IIPH2O2) : it will be noticed that in composition they differ from each other simply in the proportion of oxygen, the molecules con- taining four, three, and two atoms respectively. In constitution they differ by the hypothetical phosphoric radical or grouping being 1 trivalent, the phosphorous bivalent, and the hypophosphorous univa- lent. These three acids and corresponding salts must not be con- j founded with pyrophosphoric and metaphosphoric acids and salts ; the . I former are acids of phosphorus ; the latter, varieties of phosphoric I acid: the former, in composition, differ from each other in the propor- tion of oxygen they contain ; the latter, by the elements of water : — Acids of Phosphorus. Varieties of Phosphoric Acid. H3PO4 phosphoric acid. H3PO4 (ortho) phosphoric acid. H2PHO3 phosphorous acid. H^P207 pyrophosphoric acid. IIPII2O2 hypophosphorous acid. IIPO3 metaphosphoric acid. When hypophosphorous acid is exposed to the air, oxygen is absorbed and phosphorous acid results ; by prolonged exposure more oxygen is absorbed and phosphoric acid is obtained. When phosphoric acid, or rather, for distinction, orthophosphoric acid is heated, every two molecules yield the elements of a molecule of water, and pyrophos- phoric acid results ; by prolonged exposure to heat more water is evolved, and metaphosphoric acid is obtained. These differences will be further evident if the formulae be written empirically, nearly all being doubled, thus : — hypophosphorous acid. IIgP206 phosphorous acid. TT P O I phosphoric acid, or ® 2 8 1 orthophosphoric acid. H4P2O7 pyrophosphoric acid. rotJtaphosphoric acid. Or thus : — phosphoric acid H«P,0«. 6^ 2^8* pyrophosphoric acid u.PA- metaphosphoric acid HgPA. gL H.P.Og. PYROPHOSPHORIC ACID. 313 From the central compound, phosphoric acid, the acids of phosphorus differ by regularly diminishing proportions of the element oxygen (see previous page), the varieties of phosphoric acid by regularly diminishing proportions of the elements of water. Pi'epare phosphorous acid by exposing a moist stick of phosphorus to the air ; a thin stream of heavy white vapor falls, which is the acid in question. The best method of collection is to place the stick in an old test-tube having a hole in the bottom, to support this tube by a funnel or otherwise, the neck of the funnel being supported in a bottle, test-glass, or tube, at the bottom of wdiich is a little water. Having collected some phosphorous acid in this wa\q apply the various tests already alluded to under Hypo- phosphorous Acid^ first carefully neutralizing the phospho- rous acid b}^ an alkali. The means by which the A^arieties of phosphoric acid are distinguished have been given under Metaphosphoric Acid. Other soluble phosphites are prepared by neutralizing phosphorous acid with alkalies, and the insoluble phosphites by double decomposition. Pyrogallig Acid. — See Tannic Acid. Pyrophosphoric Acid (H^P20.) and other Pyrophos- phates. — Heat ordinary phosphate of sodium (Na^HPO^, I2H2O) in a crucible ; water of crystallization is first evolved, and diy phosphate (Na2HPOJ remains. Continue the heat to redness ; two molecules of the salt yield one molecule of water, and a salt having new properties is obtained : — 2Na2HPO, — H 2 O = Na,P20,. It is termed pyrophosphate of sodium, in allusion to its origin (nit’p, pur, fire). Other pyrophosphates are produced in a similar way, or by double decomposition and precipitation, or by neutraliz- ing pyrophosphoric acid by an oxide, hydrate, or carbonate. Possi- bly the pyrophosphates are only compounds or orthophosphates with metaphosphates : — Na^P207 = Na3PO^, NaPOg. Tests. — To solution of a pyrophosphate add solution of nitrate of silver ; white pyrophosphate of silver (Ag^P207) falls as a dense white powder, differing much in appearance from the white gelatinous metaphosphate of silver or the yellow orthophosphate. To pyrophosphoric acid, or to a pyrophosphate mixed with acetic acid, add an aqueous solution of albumen (white of egg) ; no precipitate occurs. Metaphosphoric acid, it will be remembered, gives a white precipitate with albumen. 27 314 SALTS OF RARER ACIDULOUS RADICALS. QUESTIONS AND EXERCISES. 600. What are the sources of lactic acid ? 601. How is lactic acid usually prepared ? 602. Name some of the plants in which malic acid is found. 603. AVhence is meconic acid derived ? 604. By what process may meconic acid be isolated ? 605. Which is the best test for the meconic radical ? 606. Distinguish meconates from sulphocyanates. 607. Give the mode of manufacture of hypophosphites. 608. How is phosphoretted hydrogen prepared ? 609. By what ready method may metaphosphoric acid be obtained for experimental purposes ? 610. Name the tests for metaphosphates. 611. How may meta- or pyro-phosphoric acid be converted into orthophosphoric acid ? 612. Describe the preparation of phosphorous acid. 613. State the relations which the acids of phosphorus bear to each other. 614. How are pyrophosphates prepared ? 615. Offer two views of the constitution of pyrophosphates. 616. Define, by formulae, metaphosphates, pyrophosphates, ortho- phosphates, phosphites, and hypophosphites. 617. Mention the tests by wdiich meta-, pyro-, and orthophosphates are analytically distinguished. 618. Name the reactions by which hyposulphites and phosphites are detected. Silicic Acid (H^SiOJ and other Silicates. — Silicates of various kinds are among the commonest of minerals. The various days are aluminium silicates ; meerschaum is an acid silicate of magnesium ; the ordinary sandstones are chiefly silica; sand, flint, quartz, agate, chalcedony, and opal are silicic anhydride or silica (SiO.J. Asbestos or amianth is a fibrous silicate of calcium and magnesium. Artifi- cial silicates are familiar under the forms of glass and earthenware. Common English wdndow-glass is usually silicate of calcium, sodium, and aluminium ; French glass, silicate of calcium and sodium ; Bohemian, chiefly silicate of potassium and calcium ; English flint- or crystal-glass for ornamental, table, and optical purposes, is mainly silicate of potassium and lead. Earthenware is mostly silicate of aluminium, (clay), with more or less of silicate of calcium, sodium, and potassium, and, in the commoner forms, iron. The various kinds of porcelain (China, Sevres, Meissen, Berlin, English), Wedgwood- ware, and stoneware are varieties of earthenware. Crucibles, bricks, and tiles are clay-silicates. Mortar is essentially silicate of calcium. Portland, Roman, and other hydraulic cements are silicates of cal- cium with more or less silicate of aluminium. Alix together a few grains of powdered flint or sand with ^ about live or six times its rveight of carbonate of sodium i SUCCINIC ACID. 315 and an equal quantity of carbonate of potassium, and fuse a little of the mixture on platinum-foil in the blowpipe- flame; the-product is a kind of soluble glass. Boil the foil in water for a few minutes, filter ; to a portion add excess of hjTlrochloric acid, evaporate the solution to dryness, and again boil the residue in water and acid; oxide of silicon, or silica,^ (Si 02 ) remains as a light, flaky, insoluble powder. The soluble glass or glass liquor of trade commonly contains 10 or 12 per cent, of soda (NallO) to 20 or 25 per cent, of silica (SiOg). The foregoing operation constitutes the test for silicates. By fusion with alkali the silicate is decomposed, and a soluble alkaline silicate formed. On addition of acid, silicic acid (H^SiO^) is set free, but remains in solution if sufficient water is present. The heat subse- quently applied eliminates water and reduces the silicic acid to silica (SiO.,), which is insoluble in water or acid. By the addition of hydro- chloric acid to soluble glass, and removal of the resulting alkaline chloride and excess of hydrochloric acid by dialysis (a process to be subsequently described), a pure aqueous solution of silicic acid may be obtained ; it readily changes into a gelatinous mass of silicic acid. Possibly some of the natural crystallized varieties of silica may have been obtained from the silica contained in such an aqueous solution, nearly all waters yielding a small quantity of silica when treated as above described. A variety of silicic acid (H 2 Si 03 ) sometimes termed dibasic, to distinguish it from the normal or tetrabasic acid (H^SiO^), results when the aqueous solution of the latter is evaporated in vacuo, Siliciuretted hydrogen, or hydride of silicon (SiH^), is a sponta- neously inflammable gas formed on treating silicide of magnesium with hydrochloric acid. It is the analogue of light carburetted hydro- gen (CH^). A liquid chloride of silicon (SiCl^) and a gaseous fluoride (SiF^) also exist. Succinic Acid (H2C4H4O4). — Amber [Succinum) is a peculiar resin usually occurring in association with coal and lignite. From the fact that fragments of coniferous fruit are frequently found in amber, and impressions of bark on its surface, it is considered to have been an exudation from a species of Pinus now probably extinct. Heated in a retort, amber yields, first, a sour aqueous liquid contain- ing acetic acid and another characteristic body appropriately termed succinic acid; second, a volatile liquid known as oil of amber (Oleum Succini Rectificatum, U. S. P.) resembling the oil yielded by most resinous substances under similar circumstances ; and, third, a pitchy residue allied ^o asphalt. The succinic acid is a normal constituent of the amber, the acetic acid is produced during distilla- tion. Succinic acid has also been found in wormwood, in several pine-resins, and in certain animal fluids, such as those of hydatid cysts and hydrocele. It may be obtained artificially from butyric, stearic, or margaric acid by oxidation. Tartaric, malic, and succinic acids are also convertible the one into the other. 316 SALTS OF RARER ACIDULOUS RADICALS. The succinates are normal (^'2^411404) and acid (E'HC^H^O J; a double succinate of potassium and hydrogen (KHC4H404,H2C4H404, H2O), analogous to the superacid oxalate, salt of sorrel^ also exists. Soluble succinates give a bulky brown precipitate with neutral ferric chloride, only" less voluminous than ferric benzoate ; a white precipitate with acetate of lead, soluble in excess of either reagent ; with nitrate of silver a white precipitate after a time ; with chloride of barium no preci- pitate at first, but a white one of succinate of barium on the addition of ammonia and alcohol. Succinates are dis- tinguished from benzoates by the last-named reaction, and by not yielding a precipitate on the addition of acids {mde p. 300). SULPHOCYANIC AciD (HCyS) AND OTHER SULPHOCYAN- ATES. — Boil together sulphur and solution of pure cyanide of potassium ; solution of sulphocyanate of potassium (KCyS) is formed. Tests, — Filter, and to a small portion of the solution add a ferric salt (Fe.^Clg) ; a deep-blood-red solution of ferric sulphocy^anate is formed. To a portion of the red liquid add hydrochloric acid ; the color is not discharged (meco- nate of iron, a salt of similar tint, is decomposed by hydro- chloric acid). In the acid liquid place a fragment or two of zinc, sulphuretted hydrogen is evolved, and the red color disappears. To another portion of the ferric sulphocyanate add solution of corrosive sublimate; the color is at once discharged. (Ferric meconate is unaffected by corrosive sublimate.) The ferric is the best test of the presence of a sulphocyanate; indirectly^ it is a good test of the pre- sence of hydrocyanic acid or cy^anogen. To solution of a sulphocy’anate add solution of mercuric nitrate; mercuric sulphocy^anate is precipitated as a wdiite l)Owder. PharaolVs Serpents . — Mercuric sulphocyanate, thoroughly washed and made up into little cones, forms the toy called Pharaoh’s ser- pent. It readily burns when ignited, the chief product being a light solid matter (mellon, C^Nj,, and the melam, which issues from the cone in a snake-like coil of extraordinary length. The other products are mercuric sulphide (of which part remains in the snake and part is volatilized), nitrogen, sulphurous, and carbonic acid gases, and vapor of metallic mercury. (For details concerning the economical manufacture of sulphocyanates see Pharmaceutical Jour- nal, second series, vol. vii. p. ,581, and p. 152.) The sulphocyanic radical (CyS) is often termed sulphocyanogcn (Scy), and its compounds regarded as sulphocyanides. Tannic Acid or Tannin is a common astrin- TANNIC ACID. 3n gent constituent of plants, but is contained in largest quantity in galls (excrescences on the oak formed by the puncture and deposited ova of an insect). English galls contain from 14 to 28 per cent, of tannic acid ; Aleppo galls {Galla, B. P. and U. S. P.) from 25 to 65 per cent. [Acidum Tannicum, B. P. and U. S. P.) Process , — Expose powdered galls (about an ounce is sufficient for the purpose of study) to a damp atmosphere for two or three days, and afterwards add sufficient ether to form a soft paste. Let this stand in a well-closed vessel for twenty-four hours, then, having quickly enveloped it in a linen cloth, submit it to strong pressure so as to separate the liquid portion, which contains the bulk of the tannin in solution. Reduce the pressed cake to powder, mix it with sufficient ether, to which one-sixteenth of its bulk of water has been added, to form again a soft paste, and press this as before. Mix the expressed liquids, and expose the mix- ture to spontaneous evaporation until, by the aid subse- quently of a little heat, it has acquired tlie consistence of a soft extract ; then place it on eartlien plates or dishes, and dry it in a hot-air chamber at a temperature not ex- ceeding 212°.^^ The resulting tannic acid occurs in “ pale yellow vesicu- lar masses or thin glistening scales, withn, strongly astrin- gent taste, and an acid reaction, readily soluble in water and rectified spirit, very sparingly soluble in pure ether, though soluble in common ether (which contains alcohol) when the ether is saturated with water. Medicinal Uses , — Tannic acid is very soluble in water, and in this form is usually administered in medicine. Its official preparations are Glyceritum Acidi Tannici^ Suppositoria Acidi Tannici, and Trochisci Acidi Tannici. Tests . — To an aqueous solution of tannic acid add aque- ous solution of gelatine, a yellowish-white flocculent com- pound of the two substances is precipitated. This is a good test of the presence of tannic acid. Tanning . — The above reaction also serves to explain the chemi- cal principle involved in tanning — the operation of converting skin into leather. In that process the skin is soaked in infusion of oak- bark [Quercus Cortex), the tannic acid of which uniting with the gelatinous tissues of the skin yields a compound very well represented by the above precipitate. The outer bark of the oak contains little or no tannic acid, and is commonly shaved off from the pieces of bark which are large enough to handle ; useless coloring matter is thus also rejected. Other infusions and extracts besides that of oak-bark (chiefly catechu, sumach, and valonia) are largely used by tanners ; 27 ^ 318 SALTS OF RARER ACIDULOUS RADICALS. if used alone these act too quickly, and give a harsh, hard, less durable leather. The tannic acid of these preparations is probably slightly different from that of oak-bark. To an aqueous solution of tannic acid add a neutral solu- tion of a ferric salt ; dark bluish-black tannate of iron is slowly^ precipitated. This is an excellent test for the pre- sence of tannic acid in vegetable infusions. The precipi- tate is the basis of nearly all black writing-ink. Ferrous salts give at first only a slight reaction with tannic acid ; but the liquid gradually darkens. Characters written with this liquid become quite black in a few hours, and are very permanent. To an aqueous solution of tannic acid add solution of tartar-emetic; tannate of antimony is precipitated. This reaction and that with gelatine are useful in the quantita- tive estimation of the amount of tannic acid in various substances. Tannic acid is a glucoside; that is, like several other substances, it yields glucose (grape-sugar) when boiled with dilute sulphuric or hydrochloric acid, the other product being gallic acid : — -f 4H,0 = 0^11, ,0^ + 3H3C,H30,. Catechu [Catechu, U. S. P., Catechu 'pallidum, B. P.), Gamhir, or Terra Japonica, Kino [Kino, B. P. and U. S. P.), Elm Bark [Ulmi Cortex, B. P.), and Slippery Elm Bark [Ulmus fulva, U. S. P.), and some other vegetable products contain a variety of tannic acid [mimo-tannic acid), which gives a greenish precipitate with neutral solutions of ferric salts. Bael fruit [Belce fr actus, B. P.), from the jEgle Marmelos, is said to owe its astringency to a variety of tannic acid. In India a jelly and preserve have long been made from the Marmelos — whence the word marmalade for similar preserves. The astringency of Pome- granate-root Bark [Granati Radicis Cortex, B. P. and U. S. P.) and Fruit [Granati Fomctus Cortex, U. S. P.) is due to tannic acid (its anthelmintic properties probably to a resinoid matter) ; and the same may be said of logwood [Hoematoxyli Lignum, B. P. and U. S. P., the color which is due to oxidized hcematoxylin). Rhatany- root [Kramerice Radix, B. P. and U. S. P.) contains about 40 per cent, of tannic acid, its active astringent principle ; rhubarb-root about 9 per cent, ^earfterry-leaves (. IJvce Ursi Folia, B. P. and U. S. P.) owe most of their therapeutic power to about 35 per cent, of tannic acid. (The cause of their influence on the kidneys is not yet traced.) They also contain arhutin, a crystalline glucoside. Gallic MczcZ(H 3 C,n 30 ^,U 20 ) {Acidum Gallicum^ B. P. and U. S. P.) occurs in small quantity in oak-galls and other vegetable substances, but is always prepared from tannic acid. Powdered galls are moistened with water and set GALLIC ACID. 319 aside in a warm place for five or six weeks, occasionally being remoistened ; fermentation occurs, and impure gallic acid is formed. The product is treated with about three times its weight of water, boiled to dissolve the gallic acid, filtered, the solution set aside to. cool, deposited gallic acid collected, drained, pressed between folds of paper to remove all mother-liquor, and, if necessary, purified by recrystal- lization from water, or by solution in hot water with animal charcoal, which absorbs coloring matter. On filtering and cooling, most of the acid separates in the form of fawn- colored slender acicular crystals. Gallic acid is soluble in about 100 times its weight of cold or 3 of boiling water, freely in spirit, sparingly in ether, also in glycerine {Gly- ceritum Acidi Gallici^ U. S. P.). The nature of the action by which gallic acid is thus produced is probably similar to that of the action of dilute acids on tannic acid. During the process oxygen is absorbed and carbonic acid gas evolved, the sugar being thus broken up or perhaps prevented from being formed. Test . — To an aqueous solution of gallic acid add a neu- tral solution of ferric salt; a bluish-black precipitate of gallate of iron falls, similar in appearance to tannate of iron. Ferrous salts are also blackened by gallic acid. To more of the solution add an aqueous solution of gelatine; no precipitate occurs. By the latter test gallic is distin- guished from tannic acid. Pyrogallic Acid (CgH^jOg). — This substance sublimes in light feathery crystals when gallic acid is heated. To an aqueous solu- tion add a neutral solution of a ferric salt, a red color is produced. To another portion add a ferrous salt; a deep-blue color results. Test for the three acids. — To three separate small quantities of milk of lime in test-tubes add, respectively, tannic, gallic, and pyro- gallic acids ; the first slowly turns brown, the second more rapidly, while the pyrogallic mixture at once assumes a beautiful purplish- red color changing to brown. These reactions are highly character- istic. They are accompanied by absorption of oxygen from the air. Use of Pyrogallic Acid in Gas-analysis. — A mixture of pyro- gallic acid and solution of potash absorbs oxygen with such rapidity and completeness that a strong solution of each, passed up succes- sively by a pipette into a graduated tube containing air or other gas, forms an excellent means of estimating free oxygen. The value of this method may be roughly proved by pouring a small quantity of each solution into a phial, immediately and firmly closing its mouth with a cork, thoroughly shaking the mixture and then removing the cork under water ; the water rushes in and occupies about one-fifth ol* the previous volume of air, indicating that the atmosphere con- tains one-fifth of its bulk of oxygen. The small amount of carbonic 320 SALTS OP RARER ACIDULOUS RADICALS. acid gas present in the air is also absorbed by the alkaline licpird'y^ in delicate experiments this thould be removed by the alkali before the addition of pyrogallic acid. Uric Acid (H.^C5H.^N^03) and other Urates. — Acidulate a few ounces of human urine with h3^drochloric acid, and set aside for twenty-four hours ; a few minute crystals of uric acid will be found adhering to the sides and bottom of the vessel and floating on the surface of the liquid. Microscopical Test . — Remove some of the floating parti- cles by a slip of glass, and examine by a powerful lens or microscope ; the chief portion will be found to be in yel- lowish semitransparent crystals, more or less square, two of the sides of which are even, and two very jagged ; but other forms are common {oide Frontispiece). Chemical Test , — Collect more of the deposit, place in a watch-glass or small white evaporating-dish, remove adhe- rent moisture by a piece of blotting or filter-paper, add a drop or two of strong nitric acid, and evaporate to dryness ; the residue will be red. When the dish is cold, add a drop of solution of ammonia ; a purplish-crimson color results. The color is deepened on the addition of a drop of solution of potash. Notes , — Uric acid (or lithic acid) and urates (or litliates) of so- dium, potassium, calcium, and ammonium are common constituents of animal excretions. Human urine contains about one part of urate (usually urate of sodium) in 1000. When more than this is present the urate is often deposited as a sediment in the excreted urine, either at once, or after standing a short time. Uric acid or other urate is also occasionally deposited before leaving the bladder, and, slowly accumulating there, forms a common variety of urinary calculus. Some urates are not definitely crystalline ; but, when treated with dilute nitric acid or a drop of solution of potash and then a drop or two of acetic acid, jagged microscopic crystals of uric acid are usually formed. — All urates yield the crimson color when treated as above described. — This color is due to a definite substance, murexid (CgHgNgOg) (from the murex, a shell-fish of similar tint) ; and the test is known as the murexid test. The formation of mu- rexid is due to the action of ammonia on alloxan (C4H.^N.^0^,4H20) and other white crj'Stalline products of the oxidation of uric acid by nitric acid. Murexid is a good dye ; it may be prepared from guano (the excrement of sea-fowl), which contains a large quantity of urate of ammonium. The excrement of the serpent is almost pure ammo- nium urate. Uric acid and the urates will be again alluded to in connection with the subject of morbid urine. I Valerianic Acid or Valeric Acid (HCJIyOg) and OTHER Valerianates. — In a test-tube place a few drops of VALERIANATES. 321 amylic alcohol (fousel oil) with a little dilute sulphuric acid and a grain or two of red chromate of potassium, cork the tube, set aside for a few hours, and then heat the mixture ; valerianic acid, of characteristic valerian-like odor, is evolved. Valerianic acid occurs naturally in valerian-root in association with the essential oil from which it is derived [vide Index), but is usually prepared artificially, by the foregoing process, from amylic alcohol, to which it bears the same relation as acetic acid does to common alcohol : — O.H.HO + O2 = HC.^H302 + H.,0 C,H,,HO + 0, == HC,H,0, + H;0. Valerianate of Sodium (NaC^H^O^) (Sodas Valerianas^ B. P.) is prepared from the valerianic acid and valerianate of amyl obtained on distilling the mixture of amylic alcohol (4 fl. ozs.), sulphuric acid (6|- fl. ozs. with 10 of water), and red chromate of potassium (9 ozs. in 10 of water). The mixture should stand for several hours before heat is ap- plied. 2(K,Cr0,,Cr03) + 8H,SO,= 2(K,S0„Cr,3S0,+8H,0 -f 30, Red chromate of Sulphuric Sulphate of potassium Water. Oxygen, potassium. acid. and chromium. (Chrome alum.) C,H,HO + 0, = HC,H,0, + H.,0 Amylic Oxygen. Valerianic Water, alcohol. acid. 2C,H„HO + 0, = + 2H,0 Amylic Oxygen. Valerianate Water. alcohol. of amyl. The distillate (70 or 80 ozs.) is saturated with soda, which not only yields valerianate of sodium with the free valerianic acid, but de- composes the valerianate of amyl produced at the same time, more valerianate of sodium being formed and some amylic alcohol set free, according to the following equations : — HC5H9O2 4- NallO = NaC^H.O^ -f H^O Valerianic Soda. Valerianate Water, acid. of sodium. + NaHO = NaCsH.O^ + HO Valerianate Soda. Valerianate Amylic of amyl. of sodium. alcohol. Prom the solution of valerianate of sodium (which should be made neutral to test-paper by careful addition of soda solution) the solid white salt is obtained by evap- oration to dryness and cautious fusion of the residue. The mass obtained on cooling should be broken up and kept in a well-closed bottle. It is entirely soluble in spirit. Other Valerianates^ as valerianate of zinc (Zinci Vale- rianus^ B. P. and U. S. P.), and ferric valerianate, may be made by double decomposition of valerianate of sodium 322 SALTS OF RARER ACIDULOUS RADICALS. witli the sulphate or other salt of the metal the valerianate of which is desired, the new valerianate precipitating or crystallizing out. A hot solution of sulphate of zinc (5| parts) and valerianate of sodium (5 parts) in water (40 parts) gives a crop of crystals of valerianate of zinc on cooling. Tests , — Heated with diluted sulphuric acid, valerianates of the metals give valerianic acid, which has a highly characteristic smell. Valerianate of sodium thus treated, and the resulting oily acid liquid purified by agitation with sulphuric acid and distillation, furnishes the Acidum Valerianicum of the United States Pharmacopoeia. Sp. gr. 933. Dry ammonia gas passed into valerianic acid gives white lamellar crystals of valerianate of ammonium (Ammonii Valerianas^ U. S. P.). The amylic alcohol (C 5 HJJHO) from which valerianates are pre- pared may contain the next lower homologue, hutylic alcohol fC^HjjHO). This, during oxidation, will be converted miohutyric acid \ (HC 4 H 7 O 2 ), the next lower homologue of valerianic acid (HCjHyOj), | and hence the various valerianates be contaminated by some buty- rates. These are detected by distillation with diluted sulphuric i acid and addition of solution of acetate of copper to the distillate, which at once becomes turbid if butyric acid be present. In this reaction valerianic and butyric acids are produced by double de- composition of the valerianate and butyrate by the sulphuric acid, and distil over on the application of heat. On the addition of acetate of copper (CU 2 O 2 H 3 O 2 ) butyrate of copper (Cu 2 C 4 H 702 ,H 20 ) is formed, and, being almost insoluble in water, is at once precipitated, or remains suspended, giving a bluish-white opalescent liquid. Valerianate of copper (CU 2 C 5 H 9 O 2 ) is also formed after some time, but is far more soluble than the butyrate, and only slowly collects in the form of geenish oily drops, which gradually pass into green- ish-blue hydrous crystalline valerianate of copper (Larocque and Huralt). . QUESTIONS AND EXERCISES. | 619. What is the constitution of nitrites? [ 620. Mention a test for nitrites in potable waters. ! 621. Which nitrite is official? 622. Give the names of some natural and artificial silicates. 623. What is “ soluble glass ?” ' 624. Distinguish between silica and silicic acid. ' 625. How are silicates detected ? 626. What is the quantivalence of silicon ? 627. Mention the sources, formulae, and analytical reactions of i succinates. 628. State the mode of manufacture and tests of sulphocyanates. 629. What proportion of tannic acid is contained in galls ? DETECTION OF ACIDULOUS RADICALS. 323 630. Describe the official process for the preparation of Tannic Acid. 631. Explain the chemistry of ‘‘ tanning.” 632. Enumerate the tests for tannic acid ? 633. What is the assumed constitution of tannic acid ? 634. Mention other official substances whose astringency is due to tannic acid. 635. How is gallic acid prepared ? 636. By what reaction is gallic distinguished from tannic acid ? 637. Mention the characteristic properties of pyrogallic acid. 638. Explain the murexid test for uric acid. 639. Describe the artificial preparation of valerianic acid and other valerianates, giving diagrams or equations. 640. What is the formula of valerianic acid ? 641. How are butyrates detected in presence of valerianates ? DETECTION OF THE ACIDULOUS RADICALS OF SALTS SOLUBLE IN WATER. Analytical operations may now be resumed, the detection of acid- ulous radicals being practised for two or three days, and then full analyses made, both for basylous and acidulous radicals. To this end a few compounds of stated metals (potassium, sodium, or ammo- nium) should be placed in the hands of the practical student for examination according to the following paragraphs and Tables. Mixtures in which both basylous and acidulous radicals may be sought should then be analyzed. In examining salts soluble in water, and concerning which no gene- ral information is obtainable, search must first be made for any basy- lous radicals by the appropriate methods [vide pages 196 or 229). Certain metals having been thus detected, a little reflection on the character of their salts will at once indicate what acidulous radicals may be, and what cannot be, present. Thus, for instance, if the sub- stance under examination is freely soluble in water, and lead is found, only the nitric and acetic radicals need be sought, none other of the lead salts than nitrate or acetate being freely soluble in water. Moreover, the salt is more likely to be acetate than nitrate of lead, for two reasons : the former is more soluble than the latter, and is by far the commoner salt of the two. Medical and pharmaceutical students have probably, in dispensing, already learned much concern- ing the solubility of salts, and whether a salt is rarely employed or in common use. And although but little dependence can be placed on the chances of a salt being present or absent according to its rarity, still the point may have its proper weight. If, in a mixture of salts, ammonium, potassium, and magnesium have been found associated with the sulphuric, nitric, and hydrochloric radicals, and we are asked how we suppose these bodies may exist in the mixture, it is far more in accordance with common sense to suggest that sal- ammoniac, nitre, and Epsom salt were originally mixed together than to suppose any other possible combination. Such appeals to expe- rience regarding the solubility or rarity of salts cannot be made by 324 DETECTION OP ACIDULOUS RADICALS. any one not previously acquainted, or insufficiently acquainted, with the characters of salts ; in such , cases the relation of a salt to water and acids can be ascertained by referring to the following Table (p. 325) of the solubility or insolubility of about five hundred of the common or rarer salts met with in chemical operations. The opposite course to the above (namely, to acertain what acidu- lous radicals are present in a mixture, and then to appeal to expe- rience to tell what basylous radicals n^y be and what cannot be present) is impracticable ; for acidulous radicals cannot be separated out, one after the other, from one and the same quantity of substance by a similar treatment to that already given for basylous radicals. Indeed such a sifting of acidulous radicals could scarcely be accom- plished at all, or only by a vast deal of labor. The basylous radicals must, therefore, be first detected. Even when the basylous radicals have been found, the acidulous radicals which may be present must be sought for singly, the only additional aid which can be brought in being the action of sulphuric acid, a barium salt, a calcium salt, nitrate of silver, and ferric chlo- ride on separate small portions of the solution under examination, as detailed in the second of the following Tables. Commence the analysis of an aqueous solution of a salt or salts, the bas 3 Tous radicals in which are known, by writing out a list of the acidulous radicals which may be, i or, if more convenient, of those which cannot be present. To this end consult the following Table (p. 325) of the solubility of salts in water. Look for the name of the metal of the salt in the vertical column; the letters S and I indicate which salts are soluble and which insoluble in water, an asterisk attached to the S meaning that the salt is slightly soluble. The acidulous part of the name is given in the top line of the Table. All the names are in alphabetical order, for facility of reference. Some of the salts marked as insoluble in Tvater are soluble in aqueous solutions of soluble salts, a few forming soluble double salts. To characterize salts as soluble, slightly soluble, or insoluble, only roughly indicates their relation to water : on the one hand, very few salts are absolutely insoluble in water ; on the other, there is a limit to the solubility of every salt. I If only one^ two^ or perhaps three given acidulous radi-'\ cals can be in the liquid^ test directly for it or them accord- j ing to the reactions gicen in the previous pages. If seceral \ may he present,^ pour small portions of the solutions^ ren- \ dered neutral if necessary by ammonia^ into five test-tubes A and add respectively sulphui'ic acid^ nitrate or chloride of .\ barium,^ chloride of calcium,, nitrate of silver,, and ferric\ chloride; then consult the Table on page 326, in order to: correctly interpret the effects these reagents may have pro- duced. DETECTION OF ACIDULOUS RADICALS. 325 •ejp.na'ex MkhXo-. •8?tqclitis -. ^-xC/^&e-. <>-. S^iXlCCh-iCQe-. 1 — i»-hM •epiqding •ej'Bqdxng mm maim •9}^qdsoqti •0pTXO I-hCQi-H*— lCC»-HI— *CQ hHH-(C/2hH t— iC/JOJhhi— tt— 11— HHHHI— CCt-HCCCQ|-HHH»-l maics-mmmmmmmmmc^.mmaimmmmmmmmmmm •0pTpOI o^. m ^ m ^ m m m ai >~A m m >--i%i m m ^ mmm m ai m m m •0]^.ipiCH |l--.. HHI-hCCo-. CQi-Hi-hCQcw. 'OpUCBiCQ e>-. ai 0-. m o— o- ai hh i— i hh i-h »-• t-H m o— h-i o-. ai i— i ai «>— »-. ai >— i *0)^uio.iii3 ^ m h-^ m ^ e^. m m <>.. 0-. i-> m mm ^ ^ e^. m ^ m ^ ^ ^ m •0;'bj;tO "m m o^.mmmm ai m m m m a^.m m ^ ^ m ».. m ^ m <>.. o^. ^m •0pi.ioiqo '0}'Baoq.ii?3 I— iCOtV. t— !►— (t— 1(— ll-Ht— II— •©-. HHO-I— (HHI— II— IK-IHHe-. CQl— (CCo-. 0-. t-HI— I *0)iu0Sjy •— 'CZ2l— II— («>-. Ow. HHO-h- <1— IH- I-HI— («V. 1— II— II— IO-. CCl— iCChHI— II— (0-. •aj'Bta0sJv •0i‘B}0Dy ai m m m m m m m m m m m o^. m m m mm m mm m m m m m 28 326 DETECTION OF ACIDULOUS RADICALS. REMARKS ON THE PRECEDING TABLE. The first point of value to be noticed in connection with this Table is one of a negative character; namely, if either of the reagents gives no reaction it is self-evident that the salts which it decomposes with production of a precipitate must be absent. Then, again, if the action of one of the reagents indicates the absence of certain acidulous radicals, those radicals cannot be precipitated by the other reagents ; thus, if the action of sulphuric acid points to the absence of sulphides, sulphites, carbonates,, cyanides, and acetates, these salts may be struck out of the other lists, and the examination of subse- quent precipitates be so far simplified. Or, if the barium precipitate is soluble in hydrochloric acid and the calcium precipitate in acetic acid, neither sulphates nor oxalates can be present. Observing these and other points of difference, which will be seen on careful and thoughtful reflection, and remembering the facts suggested by a knowledge of what basylous radicals are present, one acidulous radi- cal after the other may be struck off as absent or present, leaving only one or two as the objects of special experiment. Among the chief difficulties to be encountered will be the separation from each other of chlorides, bromides, iodides, and cyanides, or of tartrates from citrates, and confirmatory tests of the presence of certain com- pounds. These may all be surmounted on referring back to the reactions of the various radicals, as described under their hydrogen salts, the acids. The rarer acidulous radicals will very seldom be met with. Ben- zoates, hippurates (which give benzoic acid), hypochlorites, hyposul- phites, nitrites, and valerianates show themselves under the sulphuric treatment. Ferrocyanides, ferridcyanides, meconates, succinates, sulphocyanates, t annates, and gallates appear among the salts whose presence is indicated by ferric chloride ; formiates, hypophosphites, malates, and others by nitrate of silver. Urates char when heated, giving an odor resembling that of burnt feathers. In actual practice the analyst nearly always has some clue to the nature of rarer substances placed in his hands. If chromium and arsenicum have been detected among the basy- lous radicals, those elements may be present in the form of chromates, arseniates, and arsenites, yielding with chloride of barium yellow chromate of barium and white arseniate and arsenite of barium, and with nitrate of silver red chromate, brown arseniate, and yellow arsenite of silver. QUESTIONS AND EXERCISES. 642. In analyzing an aqueous solution of salts, for which radicals would you first search, the basylous or the acidulous ? and why ? 643. In an aqueous solution there have been found magnesium (Mg) and potassium (K), with the sulphuric radical (SO 4 ), and iodine (I) ; state the nature of the salts which were originally dis- 328 GENERAL QUALITATIVE ANALYSIS. solved in the water, and mention the principles which guide you in the conclusions. 644. Give a sketch of the method by which to analyze a neutral ■ or only faintly acid aqueous liquid for the acidulous radical of salts. In what stage of the process would the following sstlts be detected ? a. Carbonates and Sulphates. h. Oxalates. c. Tartrates and Nitrates. d. Acetates and Sulphites. e. Bromides and Cyanides. /. Borates. g. Iodides and Phosphates. li. Chlorates, Oxalates, and Acetates. i. Chlorides and Iodides. j. Sulphites. i k. Sulphides, Carbonates, and Nitrates. | l. Citrates and Sulphates. ' 645. Nitrate of silver gives no precipitate in an aqueous solution ; | what salts may be present ? | 646. Chloride of barium gives no precipitates in a neutral solu- i tion, but nitrate of silver a white ; what acidulous radicals are indi- [ cated ? j 647. Ferric chloride produces a deep red color in a solution, chlo- i ride of calcium yielding no precipitate ; what salts may be present, ; and how might they be distinguished from each other ? ] 648. Ferric chloride gives a black precipitate in a solution in i which sulphuric acid develops no odor ; to what is the effect due ? AI^ALYSIS OF SALTS, SINGLE OR MIXED, SOLUBLE OR INSOLUBLE. I Thus far all material ’^substances, especially those of pharmaceu- | tical interest, have been regarded as being definite compounds, and j as having certain well-defined parts, termed, for convenience, basy- lous and acidulous respectively : moreover attention has been de- : signedly restricted to those definite compounds which are soluble in water. ^^But there are many substances having no definite or known composition ; and of those having definite composition there are many having no definite or ascertained parts. Again, of those having definite composition, and whose constitution admits of the ^ entertainment of theory, there are many insoluble in water. Chemical substances of whose composition or constitution little or f nothing is at present known, are chiefly of animal and vegetable origin, and figure in tables of analysis under the convenient collec- tive title of “ extractive matter;” they are not of immediate impor- tance, and may be omitted. PRELIMINARY EXAMINATIONS. 329 Of substances which are definite in composition, but whose parts or radicals, if they have any, are unknown or imperfectly known, there are only a few (such as the alkaloids, amylaceous and saccha- rine matters, the glucosides, alcoholic bodies, albuminoid, fatty, resinoid, and colorific substances) which have any considerable amount of pharmaceutical interest ; these will be noticed subsequently. Definite compounds most frequently present themselves ; and of these by far the larger proportion (namely, the salts soluble in water) have already been fully studied. There remain, however, many salts which are insoluble in water, but which must be brought into a state of solution before they can be effectively studied from an analytical, pharmaceutical, or a physiological point of view. The next subject of laboratory work is therefore the analysis of substances which may or may not be soluble in water. This will involve no other analyti- cal schemes than those which have been given, will in only one or two cases increase the difficulty of the analysis of the precipitate pro- duced by a group-reagent, but will give roundness, completeness, and^ a practical bearing to the reader’s analytical knowledge. Such a procedure will at the same time bring into notice the methods by which substances insoluble in water are manipulated for pharmaceu- tical purposes, or made available for use as food by plants, or as food and medicine by man and animals generally. Preliminary Examination of Solid [chiefly mineral) Salts. Before attempting to dissolve a salt for analysis, its appearance and other physical properties should be noted, and the influence of heat and strong sulphuric acid be ascertained. If the operator knows how to interpret what is thus observed, and to what extent to place confidence in the observations, he may more certainly obtain a high degree of precision in analysis, and will always gain some valuable negative information. But if he has only slight experience of the appearance and general properties of bodies, or has the habit of turn- ing what should be inferences from tentative processes into foregone conclusions, he should omit the preliminary examination altogether, or only follow it out under the guidance of a judicious tutor ; for it is impracticable here to do more than hint at the results which may be obtained by such an examination, or to so adapt description as to prevent a student from allowing unnecessary weight to precon- ceived ideas. Whatever be the course pursued, short memoranda describing re- sults should invariably be entered in the note book. 1. Examine thephy^sical characters of the salt in various ways, but never, or only rarely, by the palate, on account of the clanger to be apprehended. If the salt is white, colored substances cannot be present ; if co- lored, the tint may indicate the nature of the substance or of one of its constituents, supposing that the learner is already acquainted with the colors of salts. Closer observation, aided perhaps by a lens, may reveal the occurrence, in a pulverulent mixture, of small 28 * 330 GENERAL QUALITATIVE ANALYSIS. crystals or pieces of a single substance ; these should be picked out by a needle and examined separately. In a powder or roughly di- vided mixture of substances, the process of sifting (through such sieves as muslin of different degrees of fineness) often mechanically separates substances, and thus greatly facilitates analysis. The body may present an undoubted metallic appearance, in which case only the metals existing under ordinary atmospheric conditions need be sought. Peculiarity in smell reveals the presence of ammonia, hydrocyanic acid, hydrosulphuric acid, etc. Between the fingers a substance is, perhaps, hard, soft, or gritty ; consequent inferences follow. Or the matter may be heavy, like the salts of barium or lead ; or light, like the carbonates and hydrates of magnesium. 2. Place a grain or two of the salt in a small dry test- tube or in a piece of ordinary tubing, closed at one end, and heat it, at first gently, then more strongly, and finally, if necessary, by the blowpipe. Gases or vapors of characteristic appearance or odor may be evolved ; such as iodine, nitrous fumes, sulphurous, hydrocyanic, or ammoniacal gases. Much steam given by a dry substance indicates either hydrates or salts containing w^ater of crystallization. (A small quantity of interstitial moisture often causes heated crystalline substance to decrepitate — from decrepo, to crackle — that is, break up with slight explosive violence, owing to the expansive force of the steam suddenly generated.) A sublimate may be obtained, due to salts of mercury or arsenicum, to oxalic or benzoic acid, or to sul- phur free or as a sulphide — a salt wholly volatile containing such substances only. The compound may blacken, pointing to the pre- sence of organic matter-^which, in common definite salts, wdll pro- bably be in the form of acetates, tartrates, and citrates, or as common salts of the alkaloids morphia, quinia, strychnia, or as starch, sugar, salicin, or in other definite or indefinite forms common in pharmacy and for which tests wull be given in subsequent pages. If no char- ring occurs, the important fact that no organic matter is present is established. The residue may change color from presence or devel- opment of oxide of zinc, oxide of iron, etc., or melt from the presence of a fusible salt and absence of any large proportion of infusible salt, or be unaltered, showing the absence of any large amount of such substances. 3. Place a grain or two of the salt in a test-tube, add a drop or two of strong sulphuric acid, cautiously smelling any gas that may be evolved ; afterward slowly heat the mixture, noticing the effect, and stopping the experiment when any sulphuric fumes begin to escape. Iodine, bromine, and nitrous or chlorinoid fumes will reveal them- selves by their color, indicating the presence of iodides, bromides, iodates, bromates, nitrates, and chlorates. The evolution of a color- le.ss gas fuming on coming into contact with air, and liaving an irri- tating odor, points to chlorides, fluorides, or nitrates. Gaseous METHODS OF EFFECTING SOLUTION. 331 products having a greenish color and odor of chlorine indicate chlo- rates, hypochlorites, or chlorides mixed with other substances. Slight sharp explosions betoken chlorates. Evolution of colorless gas may proceed from cyanides, acetates, sulphides, sulphites, carbo- nates, or oxalates. Charring will be due to citrates, tartrates, or other organic matter. If none of these effects are produced, most of the bodies are absent or only present in minute quantity. The sub- stances apparently unaffected by the treatment are metallic oxides, borates, sulphates, and phosphates. 4. Exposure of the substance to the blowpipe-flarae, on platinum vrire with or without a bead of borax or of micro- cosmic salt (phosphate of sodium, ammonium, and hydro- gen, NaAinHPOJ — on platinum foil, in a porcelain crucible, or on a crucible lid with or without carbonate of sodium — on charcoal, alone or in conjunction with carbonate of sodium, cyanide of potassium, or nitrate of cobalt, will sometimes yield important information, especially to one who has devoted much attention to reactions producible by the blowpipe-flame. The interior portions of the flame con- sist of hydrocarbon gases heated to a temperature at which they combine with oxygen with great avidity, abstracting that element from metallic oxides or other oxidized sub- stance which maybe brought within their influence; the exterior portions, on the other hand, contain' excess of heated oxygen ; the former is the reducing^ the latter the oxidizing part of the flame. The medical or pharmaceutical student, however, will seldom have time to work out this subject to an extent sufficient to make it a trustworthy guide in analysis. (See Plattner and Muspratt On the Use of the Blowq^ipe,’^ and a chapter in Galloway’s ‘‘Manual of Qualitative Analysis.”) Methods of dissolving and analyzing single or mixed solid substances. Having submitted the substance to 'preliminary examination, proceed to dissolve and analyze by the following methods. These operations consist in treating a substance well powdered, consecu- tively with cold or hot water, hydrochloric acid, nitric acid, nitro- hydrochloric acid, or fusion with alkaline carbonates and solu- tion of the product in water and acid. Resulting liquids are analyzed in the manner already described, or by slightly modified processes as detailed in the following paragraphs. Solution in Water. — Boil about a grain of the salt pre- sented for analysis in about a third of a test-tubeful of w ater. If it dissolves prepare a solution of about 20 or 30 332 GENERAL QUALITATIVE ANALYSIS. grains in half an ounce or more of water, and proceed with the analysis in the usual way^ testing first for the basy- lous radical or radicals by the proper group reagents (HCl, H^S, AmllS, Ani.^CO,, Am.^HPOJ, pp. 199 or 230, and then for the acidulous radical or radicals, directly or by aid of the prescribed reagents (H^SO^, BaCl^, CaCl^, AgNO.„ Fe,Cl„), p. 326. If the salt is not wholly dissolved by the water, ascer- tain whether or not any has entered into solution, by filtering, if necessary, and evaporating a drop or two of the clear liquid to dryness on platinum foil ; the presence or absence of a residue gives the information sought. If anything is dissolved, prepare a sufficient quantity of solu- tion for analysis ancl proceed as usual, reserving the in- soluble portion of the mixture, after thoroughly exhausting with water for subsequent treatment by acids. Solution in Hydrochloric Acid. — If the salt is insoluble in water, digest about a grain of it (or of the insoluble portion of a mixed salt) in a few drops of hydrochloric acid, adding water, and boiling if necessary. If the salt w'holly dissolves, prepare a sufficient quantity of the liquid, noticing whether or not any effervescence (due to the presence of sulphides, sulphites, carbonates, or cyanides) occurs, and proceed with the analysis as before, except that the first step, the addition of hydrochloric acid, may be omitted. llie analysis of this solution will in most repects he simpler than that of an aqueous solution, inasmuch as the majority of salts (all those soluble in water) will be absent. This acid solution will, in short, only contain : chlorides produced by the action of the hydrochloric acid on sulphides, sulphites, carbonates, cyanides, oxides, and hy- drates ; and certain borates, oxalates, phosphates, tartrates, and citrates (possibly silicates and fluorides) which are insoluble in water but soluble in acids without apparent decomposition. The first four — sulphides, sulphites, carbonates, and cyanides — will have revealed themselves by the occurrence of effervescence during solu- tion ; and the presence of oxides and hydrates may often be inferred by the absence of compatible acidulous radicals. The borates, oxa- lates, phosphates, tartrates, and citrates alluded to will be reprecipi- tated in the general analj^sis as soon as the acid of the solution is neutralized ; that is, will come down in their original state when ammonia and sulphydrate of ammonium are added in the usual course. Of these precipitates, only the oxalate of calcium and the phosphates of calcium and magnesium need occupy attention now ; for oxalate and phosphate of barium seldom or never occur, and the borates, tartrates, and citrates met with in medicine or in general analysis are all soluble in water. These phosphates and oxalates, METHODS OF EFFECTING SOLUTION. 333 then, will be precipitated in the course of analysis along with iron, their presence not interfering with the detection of any other metal. If, from the unusual light color of the ferric precipitate, phosphates and oxalates are suspected, the precipitate is treated according to the following Table (reference to which should be inserted in the Table for metals, under Fe, pp. 199 and 230). PRECIPITATE OP PHOSPHATES, OXALATES, AND FERRIC HYDRATE. Dissolve in HCl, add citric acid, then NH^HO, and filter. Filtrate Fe Add HCl and K,Pcy Precipitate. Ca32PO„ CaC,04, Mg,2PO,. Boil in acetic acid and filter. Blue ppt. Insoluble Filtrate CaCA- Ca 32 P 04 , Mg 32 P 04 . White. Add Am 2 C 204 , stir, filter. Precipitate white, indicating Ca 32 PO,. Filtrate, Add AmHO. White ppt. MgNH.PO,. In analyzing phosphates and oxalates advantage is also frequently taken of the facts that the phosphoric radical is wholly removed from solution of phosphates in acid by the addition of an alkaline acetate, ferric chloride, and subsequent ebullition, as described under “ Phosphoric Acid” (p. 293), and that dry oxalates are converted into carbonates by heat, as mentioned under “ Oxalic Acid” (p. 282). Certain arseniates and arsenites, insoluble in water but soluble in hydrochloric acid, may accompany the above phosphates and oxalates if from-any cause hydrosulphuric acid gas has not been previously passed through the solution, or passed for an insufficient length of time. If the substance insoluble in water does not wholly dis- solve in hydrochloric acid, ascertain if any has entered into solution, by" filtering, if necessary, and evaporating a drop of the clear liquid to dryness on platinum foil ; the pre- sence or absence of a residue gives the information sought. If anything is dissolved, prepare a sufficient quantity of solution for analysis, and proceed as usual, reserving the insoluble portion of the mixture, after thoroughly exhaust- ing with hydrochloric acid and well washing with water, for the following treatment by nitric acid. 334 GENERAL QUALITATIVE ANALYSIS. Solution in Nitric Acid. — If the salt is insoluble in M^ater and hydrochloric acid, boil it (or that part of it which is insoluble in those menstrua) in a few drops of nitric acid. If it wholly dissolves, remove excess of acid by evaporation, dilute with water, and proceed with the analysis. This nitric solution can contain only very few substances ; for nearly all salts soluble in nitric acid are also soluble in hydrochloric acid, and therefore will have been previously removed. Some of the metals, however (Ag, Cu, Hg, Pb, Bi), as well as amalgams and alloys, un- affected or scarcely affected by hydrochloric acid, are readily attacked and dissolved by nitric acid. Many of the sulphides, also insoluble in hydrochloric acid, are dissolved by nitric acid, usually with sepa- ration of sulphur. Calomel is converted, by long boiling with nitric acid, into mercuric chloride and nitrate. The nitrates here produced are soluble in water. 'Jliis nitric solution, as well as the hydrochloric and aqueous solu- tions, should be examined separately. Apparently time would be saved by mixing the three solutions together and making one analysis. But the object of the analyst is to separate every radical from every other ; and when this has been partially accomplished by solvents, it would be unwise to again mix and separate a second time. More- over, solvents often do what the chemical reagents cannot — namely, separate salts from each other. This is important, inasmuch as the end to be obtained in analysis is not only an enumeration of the radicals present, but a statement of the actual condition in which they are present ; the analyst must, if possible, state of what salts a given mixture was originally formed — how the basylous and acidulous radicals were originally distributed. In attempting this, much must be left to theoretical considerations ; but a process by which the salts themselves are separated is of trustworthy practical assistance ; hence the chief advantage of analyzing separately the solutions re- sulting from the action of water and acids on a solid substance. Solution in Nitro- Hydrochloric Acid. — If the salt or any part of a mixture of salts is insoluble in water, hydro- chloric acid, and nitric acid, digest it in nitro-hydrochloric acid, boiling, if necessary ; evaporate to remove excess of acid, dilute, and proceed as before. 1 ! Sulphide of mercury and substances only slowly attacked by hydro- j chloric or nitric acid, as, for example, calomel and ignited ferric v oxide, are sufficiently altered by the free chlorine of aqua regia to ji become soluble. If the substance is insoluble in water and acids^ it is one I or more of the following substances: Sand and certain |l silicates, such as pipeclay and other cla 3 's ; fluor s^iar ; ;; cryolite (3NaF,AlF3); sulphates of barium, strontium, and •! possibl}" calcium; tinstone; glass; felspar (double silicate : ANALYSIS OF SUBSTANCES. 335 of aluminium and other metals) ; chloride of silver ; sul- phate of lead. It may also be or contain carbon or car- bonaceous matter, in which case it is black and combustible, burning entirely or partially away when heated in the air— or be or contain sulphur, in which case sulphurous gas is evolved, detected by its odor, when the substance is exposed to heat. For the other substances proceed accord- ing to the following (Bloxam’s) method : — Four or five grains of the substance are intimately mixed with twice the quantity of dried carbonate of sodium, and this mixture well rubbed in a mortar with five times its weight of dejiagratmg Jiux (1 of finely powdered charcoal to 6 of nitre). The resulting powder is placed in a thin porcelain dish, or crucible, or clean iron tray, and a lighted match applied to the centre of the heap. Deflagration ensues, and decomposition of the various substances occurs, the acidulous radicals going to the alkali-metals to form salts soluble in water, the basylous radicals being simultaneously converted into carbonates or oxides. The mass is boiled in water for a few minutes, the mixture fil- tered, and the residue well washed. The filtrate may then be examined for acidulous radicals and aluminium, and the residue dissolved in dilute hydrochloric acid and analyzed by the ordinary method. The only substance which resists this treatment is chrome-iron-ore. To detect alkali in felspar, glass, or cryolite, Bloxam recommends deflagration of the powdered mineral with one part of sulphur and six of nitrate of barium. The mass is boiled in water, the mixture filtered, hydrate and carbonate of ammonium added to remove barium, the mixture again filtered, and the filtrate evaporated and examined for alkalies by the usual process. QUALITATIVE ANALYSIS OF SUBSTANCES HAVING UNKNOWN PEOPERTIES. Substances are presented to the analyst in one of the three forms in which all matter exists — namely, solid, liquid, or gaseous. The method of analysis in the case of solid bodies has just been described (pp. 329-35). In the case of liquids^ the solvents as well as the dis- solved matters claim attention. A few drops are evapo- rated to dryness on platinum foil to ascertain if solid mat- 33f> GENERAL QUALITATIVE ANALYSTS. ter of any kind is present ; the liquid is tested by red and blue litmus paper to ascertain if free alkalies, free acids, or neither are present ; a few drops are heated in a test-tube and the odor of any vapor noticed, a piece of glass tubing bent to a right angle being, if necessary, adapted to the test-tube by a cork, and some of the distilled liquid collected and examined ; finally, the usual group-reagents for the several basylous and acidulous radicals are consecutively applied. Proceeding in this way, the student, who has already had some experience in pharmacy, will not be likely to overlook such solvents as water, acids, alcohol, ether, fixed oils, and essential oils, or to miss the substances which these menstrua may hold in solution. He must not, however, suppose that he will always be able to qualitatively analyze, say, a bottle of medicine ; for the various infusions, decoc- tions, tinctures, wines, syrups, liniments, confections, extracts, pill- masses, and powders contain vegetable matters, most of which at present are quite beyond the reach of the analyst. Neither the highest skill in analysis nor the largest amount of experience con- cerning the odor, appearance, taste, and uses of drugs is sufficient for the detection of all these vegetable matters. Skill and expe- rience combined, however, will do much, and in most cases even so difficult a task as the one just mentioned be accomplished with reasonable success. Qualitative analysis alone will not enable the experimenter to produce a mixture of substances similar to that analyzed ; to this end recourse must be had to quantitative analysis, a subject reserved for subsequent consideration. Gas-analysis, or Eudiometry (from svhia, eudia, calm air, and fietpov, metron, a measure, in allusion to the eudiometer, an instru- ment used in measuring the proportion and, as the early chemists thought, the salubrity of the gases of the air), is a branch of experi-tj mental investigation, chiefly of a quantitative character, concerning which information must be sought in other treatises. The analysis of atmospheric air from various localities, coal-gas, and gases obtained in chemical researches, involves operations which are scarcely within the sphere of Chemistry applied to Medicine. Beyond the recogni- 1 tion, therefore, of oxygen, hydrogen, nitrogen, carbonic, sulphurous,! and hydrosulphuric acid gases, the experimental consideration of the chemistry of gaseous bodies may be omitted. Their study, however, should not be neglected, as existing conceptions of the constitution of chemical substances are largely dependent on the observed rela- 1 tions of the volumes of gaseous compounds to their elements. Tlie l best work on this subject is a small book by Hofmann, ‘ Introduction I to Modern Chemistry.’ ■ Spectral Analysis . — It may be as well to state here that the pre- ' liminary and final examinations of minute quantities of solid matter may, in certain cases, profitably include their exposure to a tempera- : ture at which they emit light, the flame being physically analyzed ; by a spectroscope. A spectroscope consists^ssentially of a prism to i decompose a ray of light into its constituent colors, with tubes and ? SPECTRAL ANALYSIS. 337 lenses to collect and transmit the ray or rays to the eye of an observer. The material to be examined is placed on the end of a platinum wire, which is then brought within the edge of a spirit-lamp or other smokeless flame ; volatilization, attended usually in the case of a compound by decomposition, at once occurs, and the whole flame is tinged with a characteristic hue. A flat ribbon of rays is next cut off by bringing near to the flame a brass tube, the cap of which is pierced by a narrow slit. At the other end of the tube, at focal dis- tance for parallel rays, is a lens, through which the ribbon of light passes to a prism ; the prism decomposes the ribbon, spreading out its constituent colors like a partially opened fan, and the colored beam or spectrum thus produced is then examined by help of a tele- scope attached by a movable joint to the stand which carries the prism and object-tube. Sodium compounds, under these circum- stances, give yellow light only, indicated by a double band of light in a position corresponding to the yellow part of an ordinary solar spectrum. The potassium spectrum is mainly composed of a red and violet band ; lithium a crimson, and at very high temperatures a blue band. Most of the other elements give equally characteristic spectra. QUESTIONS AND EXERCISES. 649. Describe the preliminary treatment to which a salt may be subjected prior to systematic analysis. 650. Mention substances which might be recognized by smell. 651. Which classes of salts are heavy, and which light ? 652. Name some bodies detectable by their color. 653. What inference may be drawn from the appearance of steam when dry substances are heated ? 654. Why do certain crystals decrepitate ? 655. If a powder sublimes on being heated, to what classes of compounds may it belong ? 656. When heat causes charring, what conclusion is drawn ? 657. No change occurring by heat, which substances cannot be present ? 658. Give examples of salts which are identified by their reaction with strong sulphuric acid ; by their comportment in the blowpipe- flame, with or without borax or microcosmic salt. 659. What are the solvents usually employed in endeavoring to obtain a substance in a state of solution, and what is the order of their application ? 660. Name a few salts which may be present in an aqueous solu- tion. 661. Mention some common compounds insoluble in water, but soluble in hydrochloric acid. 662. What substances are attacked only by nitric acid or nitro- hydrochloric acid ? i 663. Sketch out a method for the complete analysis of a liquid sus- I pected to be an aqueous solution of neutral salts. ! 29 338 THE ALKALOIDS. 664. How can earthy phosphates and oxalates with ferric oxide be separated from each other ? 665. By what process may substances insoluble in water or acids be analyzed ? 666. How are different solvents recognized? 667. By what methods would you attempt the analysis of a bottle of medicine ? 668. Give a short sketch of spectral analysis. CHEMISTRY OF CERTAIN SUBSTANCES OF VEGETABLE AND ANIMAL ORIGIN. Except alcohol and a few acids, the compounds which have hitherto engaged notice have been of mineral origin. But the two other , kingdoms of nature, the animal and vegetable, furnish a large num- ber of medicinal substances. These, indeed, when discovered, were producible only by highly organized living structures, and were hence termed organic compounds.* A few of these compounds, of common occurrence in pharmacy and possessing prominent characteristics, may now occupy attention ; reactions of the alkaloids and some other principles may be per- formed, and the methods of examining morbid urine be experimentally studied. There will then remain to be studied certain galenical, as distinguished from chemical, substances, solid and liquid, which can only be fairly regarded from a pharmacist’s point of view, and a still larger number, doubtless, not yet brought within the grasp of the chemist, and of which, therefore, we must at present be content to remain in ignorance. An opportunity, however, will be afforded of i noticing the effect of a mixture of definite and indefinite organic mat- ter, such as a vomit or the contents of a stomach, in masking or pre- venting the reaction by which mineral and vegetable poisons are i detected. ALKALOIDS. j' Constitution of Alkaloids or Organic Bases. | The alkaloids, or alkali-like (ftSoj, eidos, likeness) bodies have ii many analogies with ammonia. Their constitution is not yet knoMii ; ji * Organic^ from opyavov^ organon^ an organ. A large numV»er of or-|j gallic compounds can now be obtained artificially — without the aid i i of a living organism: hence the distinction fuimerly drawn between ;• organic and inorganic compounds, organic and inorganic chemistry, 'i is fast breaking down. NOMENCLATURE. 339 but they are probably derivative of a single molecule of ammonia (NH3), or of double, triple, or quadruple molecules (N2H(., N3H9, N4H12). A large number of artificial alkaloids or organic bases having such a constitution have already been formed. Those are termed amines, and are primary, secondary, and tertiary according as one, two, or three atoms of hydrogen in ammonia (the tri-hydro- gen amine) have been displaced by radicals; as seen in the following general formulae (R = any univalent radical. Vide Index, “ Alcohol radicals’’) — R) R H In R h] H R) R \ N; R ) or the following examples — H H Etliylamine or ethylia. N N C,H H Diethylamine or diethylia. N 0,H, 0 , 11 , Triethylaiaine or tryethylia. The three classes have also been termed amidogen-, imidogen-, and nitrile-bases. Propylamine or trytylia (C3H7HHN) is a volatile oil, one of the products resulting from the destructive distillation of bones and other animal matters. The displacing radicals may be similar or different ; and, while the radical displacing one atom of hydrogen is keeping its place, any of the many known radicals may occupy the position of one or both of the other atoms of hydrogen. Thus, for example, we have methyl- etliyl-amyl-amine (CH3C2H5C5H11N, or MeEtAyN), a colorless, oily body, of agreeable aromatic odor. The organic bases derived from one molecule of ammonia are termed monamines ; from two molecules, diamines ; from three, tria- mines ; and from four, tetramines : — R] R2) R,) R In R^N, R3IN3 rJ Rj Ra) Raf In these amines any bivalent, trivalent, or quadrivalent radical may occupy the place of two, three, or four univalent radicals. Attempts to form artificially the natural organic bases have hitherto failed ; but the primary, secondary, or tertiary character of some of them has been indicated by the introduction or elimination of methyl, ethyl, and other radicals for hydrogen. Note on Nomenclature . — The first syllables of the names of the natural alkaloids recall the name of the plant whence they were ob- tained, or some characteristic property. It is to be regretted that the last syllable is not either ine or ia, instead of sometimes one and sometimes the other: general usage seems to be in favor of the lat- ter, a plan that distinguishes the alkaloids from some other sub- stances the names of which end in ine, as chlorine, bromine, iodine, fluorine, glycerine, gelatine, etc. The names of the salts of the alka- loids are given on the assumption that the acid unites with the alka- 340 THE ALKALOIDS. loid without decomposition. Thus hydrochlorate of morphia is re- garded as morphia with hydrochloric acid just as we might assume sal-ammoniac to be ammonia (NHg) with hydrochloric acid (HCl), and name it hydrochlorate of ammonia (NH3HCI) instead of chloride of ammonium (NH^Cl). Antidotes. — In cases of poisoning by alkaloids, emetics and the stomach-pump must be relied on rather than chemical agents. Astringent liquids may be administered, as tannic acid precipitates many of the alkaloids from their aqueous solution, absorption of the poison being thus possibly retarded. MORPHIA, OR MORPHINE. Formula Ci^HjgNOg, H2O. Molecular weight 303. Occurrence. — Morphia occurs in opium (the inspissated juice of the fruit, Papaveris capsulce, of the White Poppy, Papaver somni- ferum) as meconate of morphia. Morphia, U. S. P., is made by adding to infusion of opium an equal bulk of alcohol, then slight excess of ammonia, and setting aside for crystalline morphia to separate. It is purified by recrystallization. Process for Hydro chlorate . — The hydrochlorate Cj7Hj9N03,HCl, SH^O {Morphias Hydrochloras, B. P.), occurs in slender white acicular crystals ; it is prepared by simply decomposing an aqueous infusion of opium with chloride of calcium, meconate of calcium and hydrochlorate of morphia being produced. (If the infusion, which is always acid, be first nearly neutralized by the cautious addition of small quantities of very dilute solution of ammonia, the chloride of calcium then at once causes a precipitate of meconate of calcium, which'^an be filtered off, leaving a colored solution of hydrochlorate of morphia. On the large scale — vide B. P. — the details are some- what different.) The salt is partially purified by crystallization from the evaporated liquid, then by treatment of the solution of the impure hydrochlorate by animal charcoal, and lastly by pre- cipitation of the morphia from the still colored liquid by ammonia and resolution of the morphia in hot dilute hydrochloric acid; hydro- chlorate of morphia separates out on cooling. The process of U. S. P. consists in neutralizing morphia by hydrochloric acid. (Morphice Murias, U. S. P.) Morphias Sulphas, U. S. P., by neutralizing morphia with sulphu- ric acid. Process for Acetate. — Acetate of morphia (Cj^HjgN 030.211^02) [Morphias Acetas, B. P. and U. S. P.) is a white pulverulent salt prepared by dissolving pure morphia in acetic acid, the morphia being prepared (B. P.) from a solution of the hydrochlorate by precipita- tion with ammonia. Eight parts of hydrochlorate yield about seven of acetate. Both the hydrochlorate and acetate of morphia are soluble in water, but the solution is not stable unless acidulated and containing alco- hol; hence the official solutions, 4 grains in one ounce — 1 in 110 MORPHIA. 341 [Liquor Morphice Hydrochloratis, B. P., and Liquor Morphice Acetatis, B. P.), consist of three parts water and i part rectified spirit, a few minims per ounce of hydrochloric or acetic acid being added. Liquor Morphice Sulphatis, U. S. P., is a solution in water. 1 in 456 . The other official preparations are Suppositoria Morphice, Trochisci Morphice, and Trochisci Morphice et Ipecacuanhce. When a simple but strong solution of acetate of morphia in water is required (for hypodermic injection) one part of the salt, if recently made, may be dissolved in six parts of water. If the acetate of morphia is old, it either will not dissolve, or, if dissolved by aid of warmth and a little acetic acid, will soon be re-deposited. The aqueous solution, however well made, cannot be kept in its normal condition for any great length of time. Other alkaloids exist in opium. In the above process a consider- able quantity of narcotine (C22lI.^sN07) remains in the exhausted opium, and may be extracted by digesting in acetic acid, filtering, precipitating by ammonia, and crystallizing from alcohol. Codeia (^18^21^^3)^20) is soluble in the slight excess of ammonia em- ployed in precipitating the morphia. From the mother-liquors there have also been obtained thehaia (C19H21NO3), papaverine (C2oIl2,N04), opianine narceia (C23H29N09), cryp- topia (C21H23NO5), meconine laudanine (C2oH2f^N04), codamine ^), pseudomorphia (‘1), protopine (O20H19NO5), laudanosine (C21II27NO4), hydrocotarnine (O12IIJ5NO3). Analytical Reactions. First Analytical Reaction, — To a minute fragment of a salt of morphia add one drop of water, and warm the mix- ture until the salt dissolves, then stir the liquid with a glass rod moistened by a strong neutral solution of per- chloride of iron ; a dirty blue color is produced. This effect is not observed in dilute solhtions. Second Analytical Reaction, — To a drop or two of a strong solution of a morphia salt in a test-tube add a minute frag- ment of iodic acid (HIO3, page 263) ; iodine is set free. Into the upper part of the tube insert a glass rod covered with mucilage of starch, and warm the solution ; dark-blue stareh|iodide is produced. If the mixture of morphia and iodic acid be shaken up with chloroform or bisulphide of carbon, a violet solution is obtained. This reaction is only confirmatory of others, as albuminous matters also reduce iodic acid. Third Analytical Reaction, — To a few drops of an aque- ous infusion of opium add a drop of neutral solution of perchloride of iron ; a red solution of meconate of iron is produced. Add solution of corrosive sublimate ; the color 29* 342 THE ALKAJ.OIDS. is not destro3^ed (as it is in the case of snlphocyanide of iron, a salt of similar tint). In cases of poisoning by a preparation of opium, this test is almost as conclusive as a direct reaction of morphia (the poison itself), meconic acid being obtainable from opium only. Other Reactions , — Add carbonate of sodium to a solu- tion of a salt of morphia; a white precipitate of morphia falls, slowly and of a crj-stalline character if the solution is dilute. Collect this precipitate and moisten it with neutral solution of perchloride of iron ; the bluisli tint above referred to is produced. Add an alkali to a solu- tion of hydrochlorate or acetate of the alkaloid ; morphia is precipitated, soluble in excess of the fixed alkali, far less readily^ so in ammonia. Moisten a particle of a morphia salt with nitric acid ; an orange-red coloration is produced. Heat morphia on platinum foil ; it burns entirely away. Apomorphia (C17HJ7NO2). Apomorphia {artb, apo, from, and morphia) is an alkaloid recently obtained from morphia by Matthiessen and Wright. It possesses remarkable physiological effects ; of a grain (in aqueous solution) injected under the skin, or | of a grain taken into the stomach, is said to produce vomiting in from four to ten minutes. Process . — Hydrochlorate of morphia is hermetically sealed in a thick tube with considerable excess of hydrochloric acid, and heated to nearly 300 ^ F. for two or three hours. The product is purified by diluting the contents of the tube with water, precipitating with bicarbonate of sodium, and treating the precipitate with ether or ^ chloroform. On shaking up the ethereal or chloroform solution (j with a very small quantity of strong hydrochloric acid, the sides of i the vessel become covered with crystals of the hydrochlorate of the { new base. These may be drained from the mother-liquor, washedj with a little cold water, in which the salt is sparingly soluble, recrys- , tallized from hot water, and dried on bibulous paper or over sul4 phuric acid. The formula (Cj^Hj^NO.^JdCl) indicates that the newl alkaloid is derived from morphia by alDstrnctipn of the elements of 1 water. Codeia, also, according to the same chemists, yields apomorphia ^ by similar treatment, a reaction that would seem to indicate that ' codeia is methyl-morphia : — C,,H^7CH3HN03 + HCl = CH3CI -f -f Codeia. Chi. of methyl. Apomorphia.J Dr. C. R. A. Wright has recently obtained several new deiHva-^ fives of codeia, r.v Q U I N I A . 343 QUESTIONS AND EXERCISES. 669. Write some general formulae of artificial alkaloids. 670. Name the substances represented by the following formulae : — 671. What is the assumed constitution of the salts of the alkaloids ? 672. Describe the treatment in cases of poisoning by alkaloids. 673. Give the process for the preparation of Hydrochlorate of Morphia. In what form does morphia occur in opium ? 674. How is Acetate of Morphia prepared ? 675. What plan is adopted for preventing the decomposition of the official solutions of morphia ? 676. Mention the analytical reactions of morphia. 677. In addition to the reaction of morphia, what test may be employed in searching for opium in a liquid or semifluid material ? 678. How is apomorphia prepared, and what are its properties ? 679. Describe the relation of morphia to codeia. QUINIA, OR QUININE. Formula C2oH24N202,3H20. Molecular weight 378. Source . — Quinia and other similar alkaloids exist in cinchona- bark as kinates. In the yellow bark ( Cinchonoe Flavce Cortex, B. P. and U. S. P.) quinia is almost exclusively present ; in the pale bark [Cinclionce Pallidoe Cortex, B. P. and U. S. P.) cinchonia is equally characteristic ; while in the red bark ( Cinclionce Euhrce Cortex, B. P. and U. S. P.) these alkaloids occur in more nearly equal pro- portions. Process for Sulphate. — Sulphate of quinia ( Quinice Sulphas, B. P.) is prepared according to the British Pharmacopoeia by treating the yellow bark wi^h dilute hydrochloric acid, precipitating the re- sulting solution of hydrochlorate of quinia by soda, and redissolving the precipitated quinia in the proper proportion of hot dilute sulphu- ric acid. The sulphate crystallizes out on cooling in silky acicular crystals containing two atoms of quinia ( 2 O 20 H 24 N 2 O 2 ), one of sul- phuric acid (H 2 SO 4 ), and seven of water of crystallization ( 7 H 2 O). In the process of the United States Pharmacopoeia lime is used instead of soda and the precipitated quinia is dis- solved in boiling alcohol, the latter recovered by distilla- tion, the residual quinia neutralized by diluted sulphuric acid, the solution treated with animal charcoal, filtered 344 THE ALKALOIDS. while hot, set aside to crystallize, and recrystallized if necessaiy. Sulphate of quinia, or, more correctly, disulphate, is only slightly soluble in water ; on the addition of dilute sulphuric acid a neutral sulphate is formed which is freely soluble. The latter salt may be obtained in large rectangular prisms, having a composition expressed by the formula The ordinary disulphate of quinia is more soluble in alcohol or alcoholic liquids than in water; hence the Tinctura Quinice, B. P., which, is a sokition (saturated at 550 or 60^ F.) of the salt in tincture of orange-peel (eight grains in the ounce). Quinia wine ( Vinum Quinice, B. P.) is a solution of neutral sulphate and citrate of quinia in orange-wine, made by dis- solving the disulphate (one grain in the ounce) in orange-wine by the help of citric acid. The only official preparation of the pure disul- phate is Pilula Quinice, containing three parts salt to one of con- fection of hips (gum arabic and honey, U. S. P.). The remaining Pharmacopoeial preparation of quinia is the mixed citrates of iron, ammonium, and quinia [Ferriet Quinice Citras, B. P. and U. S. P.), the well-known scale compound. It is made by dissolving ferric hydrate, prepared from ferric sulphate, and quinia, prepared from the sulphate, in solution of citric acid, ammonia also being added : the liquid, evaporated to a syrupy consistence and dried in thin layers on glass plates, yields the usual greenish-yellow scales {vide p. 130). Qmmce Valerianas, U. S. P., is made by dissolving precipitated quinia in warm aqueous solution of valerianic acid and setting aside to crystallize. Citrate of Quinia has the formula (C2oH24N202)2,H3C6H507, Reactions. First Analytical Reaction . — To a soli(t^n of quinia or its salts in faintly acid water add fresh chlorine-water and then solution of ammonia; a green coloration (thalleiochin) is produced. According to Fliickiger, in very dilute solu- | tions of quinine bromine-vapor is more useful than chlorine [, for this reaction. j Second Analytical Reaction . — Repeat the foregoing re- action. but precede the addition of ammonia by solution of I ferrocyanide of potassium ; an evanescent red coloration is i ^produced (Livonius and Vogel). Third Analytical Reaction. — Quinia may be impure from the piesence of the other alkaloids (chiefly quinidia, cinchoiiia) of cinchona-bark ; the following tests will determine the point. The ' first is Stoddart’s modification of Liebig’s process. nto a glass tube or bottle put ten grains of the suspected I It, dissolve in 10 minims of dilute sulphuric acid and 60 QU I NI A. 345 minims of distilled water ; to this add 150 minims of pure ether, 3 minims of spirits of wine, and 40 minims of a solu- tion of soda (1 part of solid hydrate to 12 of water). Agitate well and set aside for twelve hours, when, if the slightest trace of quinidia and cinchonia be present, they will be seen at the line of separation between the ether and solution of sulphate of sodium. If only a small percentage of quinidia be present, it will appear as an oily substratum, appearing under a lens as dust, from the minuteness of its particles. Cinchonia will appear more decidedlj" crystalline. With a little practice the eye will easily distinguish which of the alkaloids is de- posited. Fourth Analytical Beaction . — This is StoddarCs chemico- microscopic test. Into an ounce of distilled water drop 10 drops of dilute sulphuric acid (British Pharmacopoeia strength). To this add 14 grains (or as much as will satu- rate the acid) of the suspected salt. Filter through paper, and to a little of the filtered solution add a few drops of solution of sulphocyanide of potassium (180 grains in 1^ ounce of water). An immediate precipitate of the several alkaloids takes place, each of which is distinct and charac- teristic. If quinia, quinidia, and cinchonia be present, they will all be seen on the slide, becoming more and more distinct during the first hour. A good plan is to place on a glass slip a drop of the solution to be tested, and to put another of tlie sulphocyanide by its side — the drops not being larger than good-sized pin-heads. Over both place a piece of thin glass, which will cause the drops to touch. Examine the line of junction under a half-inch object-glass, when the crystals are readily seen and recognized. By this method xo^oo ^ grain of quinidia or cinchonia may be easily detected. The particles arrange themselves into the respective groups — the long slender needles of the quinia salt, the round crystalline masses of the quinidia, and the large well-formed prisms of the cinchonia salts. This re- action is sufficiently constant to enable an observer who has accustomed himself to the microscopic appearance of the three pure sulphocyanides to at once distinguish the respective salts from each other. The sulphoc 3 ’anide-of-potassium solution should be of the strength indicated. If not at hand it may quickly" be made, sufficiently pure for this reaction, by the following process : C^^anide of potassium (fused), sublimed sulphur, of each 120 grains; distilled water an ounce and a half. Boil in a 346 THE ALKALOIDS. glass flask for fifteen minutes, filter, and make up the quantity to 1^ ounce with sufficient distilled water. A small quantity of quinia in much cinchonia or quinidia cannot be recognized by the above reaction. Therefore, before concluding that no quinia is present in a specimen of those alkaloids, the sample should be treated with ether, filtered, the solution evaporated to dryness, and the residue, if any, examined for quinia. Other Characters, — Concentrated sulphuric acid dis- solves quinia with production of only a faint yellow color; salicin, with which quinia may possibly be adulterated, slowly gives, under the same circumstances, a deep red. ^ Concentrated nitric acid dissolves quinia, yielding a | colorless solution ; on heating, the solution becomes yel- lowish. Quinia and its salts, heated on platinum foil, burn en- tirely away. Salicin in quinia may be detected by several other tests {cide “ Salicine^' in Index). Cinchonia or Cinchonine (C.^qH.^^N.^O) and quinia are distin- guished from morphia by non-solubility of the alkaloid precipitated by a fixed alkali in excess of the alkaline solution. They are dis- tinguished from each other by the solubility of the precipitated quinia and insolubility of cinchonia when ether is added to the alkaline mixture. Cinchonia, moreover, does not give the green coloration with chlorine-water and ammonia. Strychnia is also pre- cipitated by fixed alkalies and insoluble in excess, but this alkaloid has such strongly marked reaction of its own as to preclude confusion. Sulphate of Cinchonia ( Cinchonioe Sulphas, U. S. P.) occurs in the mother-liquors of sulphate of quinia, and is directly prepared from several kinds of bark. It forms white, shining crystals, having the form of short, oblique prisms, with dihedral summits. Like sul- phate of quinia, when heated, it fuses to a resinoid mass of a rich red color. It dissolves in fifty-four parts of cold water, in much less boiling water, in seven parts of alcohol, and very sparingly in ether. Its aqueous solution gives with terchloride of gold a yellow precipi- tate, and with chloride of calcium a white one. Ammonia, added to its solution in chlorine water, causes a white precipitate. If the salt be rubbed with water of ammonia, and then treated with ether, the cinchonia, separated by the former, will not be dissolved by the latter. Quinidia or Quinidine is an isomer of quinia, and Cinchonidia i or Cinchonidine an isomer of cinchonia. Cinchovatia or Cincho- ! vatine occurs in a particular variety of cinchona-bark. Quinicia or * Qainicine and Cinchonicia or Cinchonicine are the products of the action of heat on quinia and cinchonia. STRYCHNIA, 34t STRYCHNIA, OR STRYCHNINE. Formula O21H22N2O2. Molecular weight 334. Source . — This alkaloid exists in Nux Yomica [Strychnos Nux Vomica, B. P. and U. S. P.) and in St. Ignatius’s bean {Strychnos Ignatia) (Ignatia, U. S. P.) chiefly in combination with lactic acid. Process. — According to the British official process for its prepara- tion [Strychnia, B. P.) the nuts, disintegrated by subjection to steam and, after drying, grinding in a coffee-mill, are exhausted with spirit, the latter removed by distillation, the extract dissolved in water, coloring and acid matters precipitated by acetate of lead, the filtered liquid evaporated to a small bulk, the strychnia precipitated by am- monia, the precipitate washed, dried, and exhausted with spirit, the spirit recovered by distillation, and the residual liquid set aside to crystallize. Crystals of strychnia having formed, the mother-liquor (which contains the brucia of the seeds) is poured away, and the crystals of strychnia washed with spirit (to remove any brucia) and recrystallized. In the U. S. P. process the rasped Nux Yomica is exhausted by very dilute hydrochloric acid, milk of lime added to the evaporated decoction to decompose the hydrochlorate of strychnia, the precipi- tated and dried mixture of strychnia and lime treated with diluted alcohol to remove brucia, and then with strong hot alcohol to dis- solve out strychnia : the alcohol having been recovered by distillation, the residual impure strychnia is dissolved in very dilute sulphuric acid, the solution decolorized by animal charcoal, evaporated, and set aside to crystallize, the crystals of sulphate of strychnia [Strychnice Sulphas, U. S. P.) redissolved in water, ammonia added to precipi- tate pure strychnia, and the latter dried. Properties. — Strychnia occurs ‘‘ in right square octahedrons or prisms, colorless and inodorous ; sparingly soluble in water, but com- municating to it its intensely bitter taste ; soluble in boiling rectified spirit and in chloroform, but not in absolute alcohol or in ether.” Reactions. First Analytical Beaction . — Place a minute particle of strj’chnia on a white plate, and near to it a small fragment of red chromate of potassium ; to each add one drop of concentrated sulphuric acid : after waiting a minute or so for the chromate to fairly tinge the acid, draw the latter, by a glass rod, over tlie strychnia spot ; a beautiful purple color is produced, quickly fading into a yellowish-red. The following oxidizing agents may be used in the place of the chromate : puce-colored oxide of lead, fragments of black oxide of manganese, ferridcyanide of potassium, or permanganate of potassium. 348 THE ALKALOIDS. This reaction is highly characteristic ; a minute fragment dissolved in much dilute alcohol, or, better, chloroform, and one drop of the liquid evaporated to dryness on a porcelain crucible-lid or other white surface, yields a residue which immediately gives the purple color on being oxidized in the manner directed. Other Reactions. — Strong sulphuric acid does not act on strychnia, even at the temperature of boiling water, a fact of which advantage is taken in separating strychnia from other organic matter/for pur- poses of toxicological analysis. Sulphocyanide of potassium pro- duces, even in dilute solutions of strychnia, a w^hite precipitate, which, under the microscope, is seen to consist of tufts of acicular crystals. Strong nitric acid does not color strychnia in the cold, and on heating only turns it yellow. The Physiological Test. — A small frog placed in an ounce of water to which of a grain of a salt (acetate) of strychnia is added, is, in two or three hours, seized with tetanic spasms on the slightest touch, and dies shortly afterwards. Strychnia has an intensely bitter taste. Cold water dissolves only part; yet this solution, even when largely diluted, is dis- tinctly bitter. Alcohol is a somewhat better solvent. The salts of the alkaloid are more soluble. The official solution [Liquor Strych- nice, B. P.) contains four grains of strychnia to the ounce, the sol- vent being three parts water, one part spirit, and a few minims (6 per ounce) of hydrochloric acid (rather more than sufficient to form hydrochlorate of strychnia). Brucia, or Brucine (C.^ 3 H 2 gN 204 , 4 H 20 ), is an alkaloid accompany- ing strychnia in Nux Vomica. It is readily distinguished by the intense red color produced when nitric acid is added to it. Igasuria is another alkaloid of Nux Vomica. This alkaloid is said to occur in no less than nine varieties, each slightly differing from the other in chemical composition. They resemble strychnia in physical properties. Distinction of Brucia from Morphia. — The red coloration pro- duced by the action of nitric acid on brucia is distinguished from that yielded by morphia by the action of reducing agents (such as stannous chloride, hyposulphite of sodium, sulphydrate of sodium), which decolorize the morphia-red, but change that of the brucia to violet and green (Cotton). Distinction of Free Alkaloids or their Salts from each Other . — This is accomplished by remembering the appearance and other phy- sical characters of the substances as met with in pharmacy, the effect of heat, the action of such solvents as water, alcohol, and ether, the influence of strong and diluted acids, strong and weak alkalies, oxi- dizing agents, chlorine-w^ater and ammonia, and other reagents. QUESTIONS AND EXERCISES. 680. What alkaloids are more or less characteristic of the different varieties of cinchona-bark ? In wdiat form do they occur ? 681. By wffiat method is Disulphate of Quinia obtained? I: ACONITI A. 349 682. Give the characters of disulphate of quinia. 683. Describe the tests for quinia. 684. How is the adulteration of disulphate of quinia by salicin detected? 685. Show how the sulphates of quinidia or cinchonia maybe proved to be present in commercial quinia. 686. How are cinchonia and quinia distinguished from morphia ? 687. Whence is strychnia obtained ? 688. Describe the official process for the isolation of strychnia. 689. Give the characters of strychnia. 690. Enumerate the tests for strychnia, and describe their mode of application. 6^. By what reagent is brucia distinguished from strychnia? 692. Distinguish between brucia and morphia. 693. By what general methods would you distinguish common alkaloids from each other ? ALKALOIDS OF LESS FREQUENT OCCURRENCE. Aconitia, Aconitina, or Aconitine (G^qH^^NO^) is an alkaloid obtained from aconite [Aconitum Napellus) leaves (.Aconiti Folia^ B. P. and U. S. P.) and root [Aconiti Radix, B. P. and U. S. P.). The alkaloid itself is only slightly sqluble in water ; it occurs in the plant in combination with a vegetable acid, forming a soluble salt. P/ 'ocess, — The official process for its preparation [Aconitia, B. P. and U. S. P.) consists in dissolving out the natural salt of the alka- loid from the root by rectified spirit, recovering the latter by distilla- tion, mixing the residue with water, filtering, precipitating the aco- nitia by ammonia, drying the precipitate and digesting it in ether (in which some of the accompanying impurities are insoluble), recover- ing the ether by distillation, dissolving the dry residue in the retort in water acidulated by sulphuric acid, again precipitating the alka- loid by ammonia, and finally washing and drying. Properties. — Aconitia usually occurs as a white powder, but has been obtained and studied in the crystalline state by Groves and by Duquesnel. It is soluble in 150 parts of cold water, 50 of hot, and much more soluble in alcohol and in ether. It is one of the most vio- lent poisons known. “ When rubbed on the skin it causes a tingling sensation, followed by prolonged numbness.” The thousandth part of a grain on the tip of the tongue produces, after a minute or so, a characteristic tingling sensation and numb- nOvSs ; larger quantities rubbed into the skin cause numbness and loss of feeling. To a strong solution of phosphoric acid (the ordinary acid concentrated over a water-bath to a syrupy consistence) a mere trace imparts a lasting violet tint (Fluckiger). Oil of vitriol turns it of a yellowish, and afterwards, dirty violet color. Several alkaloids have been obtained from different species and varieties of aconite. They are under research by chemists. Unguentum Aconitice, B. P., contains eight grains of the alkaloid to one ounce of prepared lard. 30 350 THE ALKALOIDS. Atropia, or Atropine (Cj^Hg^NOg), exists in the Belladonna, or Deadly Nightshade [Atropa Belladonna: Belladonnce Folia et RadiXy B. P. and U. S. P.), as soluble acid malate of atropia. Process . — It is obtained in the pure state by exhausting the root with spirit, precipitating the acid and some coloring-matter by lime, filtering, adding sulphuric acid to form sulphate of atropia (which is somewhat less liable to decomposition during subsequent operations than the alkaloid itself), recovering most of the spirit by distillation, adding water to the residue, and evaporating till the remaining spirit is removed ; solution of carbonate of potassium is then poured in till the liquid is nearly but not quite neutral, by which resinous matter is precipitated; the latter is filtered away, excess of carbonate of potassium then added, and the liberated atropia dissolved out by shaking the liquid with chloroform. The latter solution, having sub- sided, is removed, the chloroform recovered by distillation, the residual atropia dissolved in warm spirit, coloring matter separated by digest- ing the liquid with animal charcoal, the solution filtered, evaporated, and set aside to deposit crystals. Soliihility . — Atropia is sparingly soluble in water, the liquid giving an alkaline reaction — more soluble in alcohol and ether. Tests. — Atropia-solutions give with perch loride of gold a yellow precipitate. One drop of a dilute aqueous solution (two grains to the ounce) powerfully dilates the pupil of the eye. It is applied on a piece of thin tissue paper or spall disk placed between the eyelid and the eye. Preparations . — The alkaloid itself {Atropia), its sulphate {Atro- pice Sulphas, a colorless powder soluble in water, made by neutral- izing atropia with sulphuric acid), their solutions (Liquor Atropice, four grains per ounce, and Liquor Atropice Sulphatis, four grains per ounce),, and an ointment ( Unguenturri Atropice, eight grains per ounce) are the preparations official in the British Pharmacopoeia. The alkaloid and its sulphate are official in the United States Phar- macopoeia. Datxirjia or Daturine, an alkaloid in Datura Stramonium or Thorn-apple (Stramonii Folia et Semina, B. P. and U. S. P.), appears to be identical with atropia. Beberia, or Beberine (C^yH^^NOg), is an alkaloid existing in the bark of Bebeeru (Nectandra Rodicei). Process . — According to the British Pharmacopoeia, it, or rather its sulphate, CggH^.^N.^Og, H 2 SO 4 (Beherice Sulp)has, B. P.), may be prepared by exhausting the bark (Nectandrce Cortex, B. P. and U. S. P.) with water acidulated by sulphuric acid, concentrating, remov- ing most of the acid by lime, filtering, precipitating the alkaloid by ammonia, filtering, drying, dissolving in spirit (in which some accom- panying matters are insoluble), recovering most of the spirit by distillation, neutralizing by dilute sulphuric acid, evaporating to dry- ness, dissolving the residual sulphate in water, evaporating to the consistence of a syrup, and spreading on glass plates, drying the pro- duct at 140^. Thus obtained, it occurs in thin dark-brown translu- cent scales, yellow when powdered, strongly bitter, soluble in water and in alcohol. BERBERIA — CONIA. 351 Tests. — Alkalies give a pale yellow precipitate of beberia when added to an aqueous solution of a salt of the alkaloid ; the precipi- tate is soluble in ether. With red chromate of potassium and sul- phuric acid beberia gives a black resin, and with nitric acid a yellow resin. Nectandria (C20H23NO4). — Drs. Maclagan and Gamgee have re- cently discovered this second alkaloid in Bebeeru bark. It differs from beberia in fusing when placed in boiling water, in being much less soluble in ether, in giving with strong sulphuric acid and black oxide of manganese a beautiful green and then violet coloration, and in having a distinct molecular weight. They are of opinion that two other alkaloids exist in Bebeeru bark. Berberia, or Berberine (C 2 oHi 7 N 04 ), is an alkaloid existing in several plants of the natural order Berberidece, in Calumba-root ( Calumbce Radix, B. P. and U. S. P.), Goldthread ( Coptis trifolia, U. S. P.) according to Mayer, and in many yellow woods. The color of the tissues of these vegetables is apparently due to berberia; for the alkaloid itself is remarkable for its beautiful yellow color. Tests. — When a dilute solution of iodine in iodide of potassium is added to solution of any salt of berberia in hot spirit, excess of iodine being carefully avoided, brilliant green spangles are deposited. The reaction is sufficiently delicate to form, according to Perrins, an excellent test of the presence of berberia. This iodo-compound polarizes light, and has other analogies with a similar quinine-salt termed herapathite. Berberia is not an official alkaloid ; but the plants in which it occurs are used as medicinal agents in all parts of the world. Process. — Berberia is readily extracted by boiling the raw material with water, evaporating the strained liquid to a soft extract, digest- ing the residue in alcohol, recovering the alcohol by distillation, boiling the residue with diluted sulphuric acid, filtering and setting aside ; the sulphate of berberia separates out, and may be purified by recrystallization from hot water. The alkaloid itself is obtained by shaking hydrate of lead with a hot aqueous solution of the sul- phate of berberia (Procter). Podophyllum-voot [Podopliylli Radix, B. P., Podophyllum, U. S. P.), contains berberia. In preparing the resin of podophyllum or May-apple [PodopjJiylli Resina, B. P. and U. S. P.) an alcoholic extract of the root is poured into water acidulated by hydrochloric acid, whereby the whole of the hydrochlorate of berberia, which is almost insoluble in dilute mineral acids, is precipitated with the resin (Maisch). No acid is ordered in U. S. P. Capsicia, or Capsicine, is an alkaloid occurring in Cayenne pep- per or Capsicum-fruit [Capsid Fructus, B. P. and U. S. P.), asso- ciated with resin and volatile oil. It is crystalline, and forms crys- tallizable salts with acids. CiSSAMPELIA, CiSSAMPELINE, PeLOSIA, Or PeLOSINE (CjgH.^jNOg), is an alkaloid occurring in the root [Pareirce Radix, B. P. and U. S. P.) of Cissampdos Pareira. It is the tonic and diuretic principle of the drug. Conia, Conylia, Conine, Conicine, or Cicutine. — Formula 352 THE ALKALOIDS. CgH^^N, or (CgHj4)"HN. This alkaloid is a volatile liquid, occur- ring in hemlock ( Conium maculcvtum). It is not official. Process. — It may be obtained by distilling hemlock-fruit ( Conii Fructtis, B. P.) with water rendered slightly alkaline by caustic soda or potash, or by similarly treating the fresh juice of the leaves. The alkaloid is a yellow oily liquid, floating on the water that distils over ; by redistillation it is obtained colorless and transparent. The salts of conia have no odor, but when moistened wdth solu- tion of an alkali yield the alkaloid, the strong smell of wffiich, at once recalling hemlock, is characteristic. Extract of hemlock leaves ( Conii Folia, B. P. and U. S. P.), to which solution of potash and boiling water have been added, forms the official Inhalation of Conia (Vapor Conice, B. P.). Tests. — Sulphuric acid turns conia purplish-red, changing to olive- green, nitric acid a blood-red ; perchloride of gold produces a yel- lowish-white preeipitate, perchloride of platinum no precipitate, in aqueous solutions. Hemlock also contains methyl-conia (CgHiJ^CngN (Kekule and Yan Planta). According to SchifF, conia, isomeric, at least, wdth the natural alka- loid, may be produced artificially by action of ammonia on butyric aldehyd and destructive distillation of the resulting compound. Daturia, or Daturine, vide Atropia. Emetia, or Emetine (C3oH44N20g). — This alkaloid is the active emetic principle of Cephcelis ipecacuanha (Ipecacuanha. B. P. and U. S. P.). It occurs in combination with ipecacuanhic acid. The nitrate is peculiarly slightly soluble in water (Lefort). In the Pul- vis Ipecacuanhce, B. P. and U. S. P., or ‘‘Dover’s Powder” (Pow- dered Ipecacuanha, 1 part : Powdered Opium, 1 part ; and Sulphate of Potassium, 8 parts), minute division of the active ingredients is promoted by prolonged trituration with sulphate of potassium, which is a very hard salt. Hyosciamia, or Hyosyamine (CigH2g,N203; other authors, CJ5H23NO3), a volatile alkaloid, is said to occur in the leaves (Hyos- cyami Folia, B. P. and U. S. P., Hyoscyami Semen, V . S. P.),and other parts of Henbane. Its effect on the eye is similar to that of atropia. Lobelia, or Lobeline, — A volatile alkaloid first isolated from the dried flowering herb Lobelia inflata (Lobelia, B. P. and U. S. P.) by Bastick. In the pure state it smells slightly of the plant, but mixed with ammonia it emits a strong and characteristic smell of the herb. Nectandria, vide Beberia. Nicotia, Nicotina, Nicotylia, or Nicotine. — Formula CjoHj^Nk^, or (L5H7)'”2N2. This is also a volatile liquid alkaloid, forming the active principle of tobacco (Nicotiana tabacum), malate and ci- trate of nicotina being the forms in which it occurs in the leaf ( Tabaci Folia, B. P. and U. S. P.). Its odor is characteristic ; like conia, it yields a precipitate with perchloride of gold ; but, unlike that alkaloid, its aqueous solutions are precipitated yellowish-white by perchloride of platinum. It is not official. PHYSOSTTGMIA — THEIA. 353 Physostigmia, or Physostigmine. — An alkaloid contained in the Calabar Bean [Physostigmatis Faba), the seed of Pliysostigma venenosum (Jobst and Hesse). A trace of it powerfully contracts the pupil of the eye ; a small quantity is highly poisonous. Fraser also isolated this principle, and termed it Eseria, from Esere, the name of this ordeal-poison at Calabar. PiPERiA, or PiPERiNE (Ct7Hj9N03), is a feeble alkaloid occurring in white, black [Piper Nigrum, B. P. and U. S. P.), long, and cu- beb pepper (Cubeba, B. P. and U. S. P.), associated with volatile oil and resin ; to these three substances the odor, flavor, and acridity belong. Piperia is obtained on boiling white pepper with alcohol, and evaporating the liquid with solution of potash, which retains re- sin. Eecrystallized from alcohol, piperia forms colorless prisms fusi- ble at 2120. With acids it forms salts, and distilled with strong alkali yields piperidia or piperidine, an alkaloid of strong chemical properties. Sanguinarina, or Sanguinarine (C 37 Hj,^N 40 g), is a colorless alka- loid obtained from the rhizome of Sanguinaria Canadensis (U. S. P.) or Blood-root. Its salts have a red, crimson, or scarlet color. SoLANiA, or SoLANiNE (C^gH^oNOig). — An alkaloid said to exist in the Woody Nightshade or Bitter-sweet [Solanum dulcamara). The dried young branches of the plant are official [Dulcamara, B. P. and U. S. P.). The alkaloid is only slightly soluble in water, alco- hol, or ether; nitric acid colors it yellow; sulphuric acid produces at first a yellow, then a violet, and finally a brown coloration. Sparteia, or Si»arteine (C|5H26N), is a poisonous volatile alka- loid occurring in Broom-tops [Scoparii Cacumina, B. P. and U. S. P.). Its discoverer, Stenhouse, considers that the diuretic principle of broom is Scoparin, a n on-poisonous body. Theia, Theine, or Caffeine (CgHjoN^02-hH20). — This alkaloid occurs in tea, coffee [Caffea, U. S. P.), Paraguay tea, guarana, and the kola-nut. Infusions and preparations of these vegetable pro- ducts ai*e used chiefly as beverages by three-fourths of the human race. It is remarkable that the instinct of man, even in his savage state, should have led him to select, as the bases of common bever- ages, just the four or five plants which out of many thousands are the only ones, so far as we know, containing theia. Theia is volatile. Large quantities may be collected by condensing the vapors evolved during the roasting of coffee on the large scale. The infusion of tea, from which astringent and coloring-matters have been precipitated by solution of subacetate of lead, and which has been evaporated to a small bulk, yields a precipitate of theia on the addition of a strong solution of carbonate of potassium. It may be crystallized from alcohol or by sublimation. Test. — Concentrated nitric acid, or a mixture of chlorate of potas- sium and hydrochloric acid, rapidly oxidizes theia, forming com- pounds which with ammonia yield a beautiful purple-red color, re- sembling the murexid obtained under similar circumstances from uric acid ; the oxidation must not be carried too far. Theine boiled with caustic potash yields methylamine*(CH 3 HHN), the vapor of which has a peculiar, characteristic odor. 30 * 354 THE ALKALOIDS. The chemical action of theia on the system is not yet made out. Liebig thinks it may aid in the production of a substance a normal amount of which is so necessary, an abnormal so unpleasant — namely, bile. Most chemists agree that it arrests the rapid consumption of tissue and consequent feeling of fatigue which is especially experi- enced after hard work with mind or body. Yeratria, or Yeratrine (C32H5.^N208). — This alkaloid, as gallate of veratria, is stated to occur in various species of Veratrum (Hel- lebore) (as Veratri Viridis Radix, B. P.), in Cevadilla {Sahadilla, B. P.), and in Colchicum autumnale [Colchici Cormus ; Colchici Semina, B. P.) ; but, according to C. Bullock, Veratrum viride contains an alkaloid soluble in ether and one insoluble in that men- struum, neither answering in chemical reactions to veratria. White Hellebore is also said to contain three other alkaloids, sahadillia or sahadilline, colchicia or colchicine, andyeri;m or jervine. A mere trace of veratria brought into contact with the mucous membrane of the nose causes violent fits of sneezing. Fuming sulphuric acid colors it yellow, red, and violet in succession. Colchicia is colored of a brownish-yellow by sulphuric acid, and of a reddish-blue turning to greenish-yellow by nitric acid. The official process for the preparation of the alkaloid ( Veratria, B. P.) consists in exhausting the disintegrated cevadilla seeds by alcohol, recovering most of the spirit by distillation, pouring the residue into w^ater, by which much resin is precipitated, filtering, and precipitating the veratria from the aqueous solution by ammonia. It is purified by washing with w^ater, solution in dilute hydrochloric acid, decolorization of the liquid by animal charcoal, reprecipitation by ammonia, w^ashing, and drying. The U. S. P. process is similar, but includes treatment of the first crude veratria by diluted sulphu- ric acid and precipitation of alkaloid by magnesia. Unguentum Veratrice, B. P., contains eight grains of the slightly impure alkaloid obtained as just described, rubbed down with half a drachm of olive oil and diffused through one ounce of prepared lard. QUESTIONS AND EXERCISES. 694. How is Aconitia prepared ? 695. Give the strengths of the official preparations of Atropia. 696. Describe the properties of atropia. 697. What is the active principle of stramonium ? 698. Mention pharmacopoeial substances containing beberia and berberia respectively. 699. Give the characters of beberia. 700. In what does nectandria differ from beberia ? 701 . Mention the characteristics of conia. 702 . What is the active principle of Ipecacuanha ? 703. Name the alkaloid of Tobacco. 704. Give the p£i,me and properties of the active principle of Cala- bar Bean. STARCH. 355 705. What are the sources of piperia ? 706. Whence is theia obtained ? 707. Describe the preparations of Yeratria. 708. State the properties of veratria. BITTEE (TONIC) SUBSTANCES. The following official articles, commonly employed medicinally in such forms as Decoction, Extract, Infusion, Tincture, contain active principles which have not yet been thoroughly examined. Some of these principles have been isolated, and a few have been obtained in the crystalline condition ; but their constitution has not been sufficiently well made out to admit of the classification of the bodies either among alkaloids, glucosides, acids, or other well-marked principles. Absinthium (Absinthin). Anth emidis flares. Aurantii cortex. Buchu folia. Canellce alhce cortex. Cascarillce cortex. Chirata. Chimaphila (Arbutin). Cusparice coHex, or Angustura. U. S. P., contains Cusparin or Angusturin. Gentiance radix. Lactuca (Lactucin). Lupidus. Maticce folia. Marruhium. Quassice lignum (Quassin, C,, Serpent an ce radix. Spigelia marilandica. Taraxaci radix (Taraxacin). AMYLACEOUS AND SACCHARINE SUBSTANCES. STARCH. Formula CgHj^O,. Processes . — Rasp or grate, or, wuth a knife, scrape a por- tion of a clean raw potato, letting the pulp fall on to a piece of muslin placed over a small dish or test-glass, and then pour a slow stream of water over the pulp ; minute par- ticles or granules of starch pass through the muslin and sink to the bottom of the vessel, fibrous matter remaining on the seive. This is potato-starch. Even diseased pota- toes furnish good starch by this method. Wheat-starch {Amyhim^ B. P. and U. S. P.) may be obtained by tying up some flour in a piece of calico and kneading the bag in a slow stream of water flowing from a tap, the washings run- ning into a deep vessel, at the bottom of which the white starch collects : the sticky matter remaining in the bag is 356 AMYLACEOUS AND SACCHARINE SUBSTANCES. gluten. Tli^ blue starch of the shops is artificially colored with smalt or indigo, to neutralize the yellow tint of recently washed linen ; it should not be used for medicinal purposes. Starch dried in mass splits up into curious columnar masses, resembling the basaltic pillars of Fingal’s Cave in Staffa, or those of the Giant ^s Causeway in the North of Ireland. The cause of the phenomenon, which may also be seen in grain-tin, is not conclusively known. Gluten is the body which gives tenacity to dough and bread. It seems to be a mixture of vegetable fibrin, vegetable casein, and an albuminous matter termed glutin. These substances and gluten itself are closely allied; each contains about 16 per cent, of nitrogen. Wheaten Flour [Farina Tritici, B. P.) contains about 72 per cent, of starch and 11 of gluten, as well as sugar, gum, fine bran, water, and ash. The compactness of barley, well seen in Husked or Pearl Barley [Hordeum Decorticatum, B. P. and U. S. P ), is said to be due to the large amount of vegetable fibrin present. During ger- mination the fibrin is destroyed, hence, probably, the cretaceous character of malt. Oatmeal [Avence Farina, U. S. P.) is very rich in albuminoid or flesh-forming constituents, containing nearly 16 per cent. Sago, U. S. P., is granulated starch from the Sago Palm. Tapioca, D. S. P., is granulated starch from the Bitter Cassava. Mucilage of Starch . — Mix two or three grains of starch with first a little and then more water, and heat to the boiling-point; mucilage of starch {Mucilago Amyli.^ B. P.) results. This mucilage or paste is not a true solution ; by long boiling, however, a portion of the starch becomes dissolved. In the latter case the starch probably becomes somewhat altered. Chemical Test . — To some of the mucilage add a little free iodine ; a deep-blue color is produced. This reaction is a very delicate test of the presence of either iodine or starch. The starch must be in the state of mucilage ; hence in testing for starch the substance supposed to contain it must be first boiled in water. The solutions used in the reactions should also be cold, or nearly so, as the blue color disappears on heating, though it is partially restored on cooling. The iodine reagent may be iodine-water or tincture of iodine. In testing for iodine its occur- rence in the free state must be insured by the addition of a drop, or even less, of chlorine-water. Excess of chlorine must be avoided, or chloride of iodine will be formed, which does not color starch. 3'he so-called iodide of starch scarcely merits the name of a chemical compound, the state of union of its constituents being feeble. Substances that attack free iodine remove that element from iodide of starch. The alkalies, hydrosulphuric acid, sulphurous acid, and other reducing agents destroy the blue color. Microscopical Test, — All kinds of starch yield the blue color DEXTRIN. 35t with iodine, showing their chemical similarity. But physically the granules of starch from different sources differ much in size and appearance when examined by the microscope with or without the aid of polarized light. The granules of potato-starch are large, of rice-starch very small, arrowroot [Maranta, U. S. P.), and wheat- starch being intermediate. By polarized light the granules of potato- starch appear as if traversed by a black cross, the wheat-starch granules, as seen in common flour, similarly influence polarized light, but oat-starch yields no such effect. (See the frontispiece plates of the original edition of Pereira’s “ Materia Medica.”) The granules of Tons les Mots [Canna^ U. S. P.) are very large. Dextrin. — Mix a grain or two of starch with about half a test-tubeful of cold water and a drop or two of sulphuric acid, and boil the mixture for a few minutes ; no mucilage is formed, and the liquid, if sufficiently boiled, yields no blue color with iodine ; the starch has become converted into dextrin. The same effect is produced if the starch is maintained at a temperature of about 320° F. for a short time. Dextrin is now largely manufactured in this way, and a paste of it used by calico-printers as a vehicle for colors ; it is termed British gum. The change ma}^ also be effected by diastase., a peculiar ferment existing in malt. Mix two equal quantities of starch with equal amounts of water, adding to one a little ground malt, then heat both slowly to the boiling-point ; the mixture without malt thickens to a paste or pudding, that with malt remains thin, its starch having become converted into dextrin. Diastase is probably the vegetable fibrin of gluten in a state of decomposition ; it is so named from [diastasis), separation, in allusion to the separation, or rather alteration, it effects among the constituent atoms of starch. Malt (the word malt is said to be derived from the Welsh mall, soft or “rotten”) is simply barley which has been softened by steeping in water, allowed to germinate slightly, and further change then arrested by the application of heat in a kiln. During germination the gluten breaks up and yields a glutinous substance termed vegetable gela- tine, diastase, and other matters. To the vegetable gelatine is due much of the “ body” of well-malted and slightly-hopped beer ; it is precipitated by tannic acid, hence the thinness of ale (pale or bitter) brewed with a large proportion of hop or other materials containing tannic acid. A portion of the diastase reacting on the starch of the barley converts it into dextrin, and, indeed, carries conversion to the further si age of grape-sugar, as will be explained immediately. The temperature to which the malt is heated is made to vary, so that the sugar of the malt may or may not be partially altered to a dark- brown coloring material ; if great, the malt is said to be high-dried, and is used in porter-brewing; if low, the product is of lighter color, and is used for ale. The diastase remaining in malt is still capable 358 AMYLACEOUS AND SACCHARINE SUBSTANCES. of converting a large quantity of starch into dextrin and sugar ; hence the makers op distillers of the various spirits operate on a mixture of malted and unmalted grain in preparing liquors for fermentation. Gum is a frequent constituent of vegetable juices, existing in large quantity in several species of acacia. According to Fremy gum is a calcium salt, sometimes partially a potassium salt of the gummic or arahic radical. The formula of gummic acid is said to be H2C,2 G um differs from dextrin in yielding oxalic acid but no mucic acid when oxidized by nitric acid. Cerasm or cherry-tree gum is an insoluble modification of acacia gum. (C,2H2oOjo) is a form of gum which is insoluble in water, but absorbs a large quantity of that liquid and forms a gelatinoid mass. It occurs largely in Tragacanth, combined, like arabin, with calcium. Pectin or vegetable jelly (032H^o028, 4H2O) is the body which gives to ex- pressed vegetable juices the property of gelatinizing. It forms the chief portion of Irish or Carrageen moss ( Chondrus crispus, U. S. P.). Isomerism. Allotropy. Polymorphism. The composition of dextrin is represented by the same formula as that of starch, namely CgH^pO^; for it has the same percentage com- position as starch. Cellulose (see next page) has also a similar for- mula. There are many other bodies similar in centesimal composition, but dissimilar in properties; such substances are termed isomeric isos, equal, and^utpo^, meros, part) ; and their condition is spoken of as one of isomerism. There is sometimes good reason for doubling or otherwise multiplying the formula of one of two isomeric bodies. Thus olefiant gas (ethylene), the chief illuminating constituent of coal- gas, is represented by the formula C2H4, while amylene, an anaesthetic liquid hydrocarbon, obtained from amylic alcohol, though having the same percentage composition as olefiant gas, is represented by the for- mula for the latter, when gaseous, is about twice and a half as heavy as the former, and must contain, therefore, in equal volumes, twice and a half as many atoms ; its formula is, consequently, for this and other reasons, constructed to represent those proportions. This variety of isomerism is termed (from Tto'kvi^. polus, many or much, and ^uspo^, part). Metastannic acid [vide p. 21 . 5 ) is a poly- meric variety of stannic acid. An illustration of a second variety of isomerism is seen in the case of cyanate of ammonium and urea, bodies already alluded to in connection with cyanic acid. These and several other pairs of chemical substances have dissimilar properties, yet are similar not only in elementary composition and in the centesimal j proportion of the elements, but also in the fact that each molecule 1 possesses the same number of atoms. But the reactions of these bodies indicate the probable nature of their construction ; and this is shown in their formula by the disposition of the symbols. Thus cyanate of ammonium is represented by the formula NII^CNO, urea • by C11^N20. Such bodies are termed metameric (from^ttfra, meta, a ; preposition denoting change, and /U£poj), and their condition spoken I of as one of metamerism. 'J'he isomerism of starch and dextrin 1 may be of a polymeric or of a metameric character ; but we do not i CELLULTN. 359 yet know which, and must therefore at present give them identical formulae. Substances similar in composition and constitution, yet differing in properties, are termed allotropic {aXKo^, alios, another, 'T'porto^, tr op os, condition). Thus ordinary phosphorus, kept at a tem- perature of about 450^ Fahr., in an atmosphere from which air is excluded, becomes red, opaque, insoluble in liquids in which ordi- nary phosphorus is soluble, oxidizes extremely slowly, and only ignites when heated to near 500^ Fahr. (red or amorphous phospho- rus). Other allotropic varieties of phosphorus are known. Another illustration of allotropy is seen in the varieties of tartaric acid, which have different optical properties, but otherwise are identical ; they are in neither of the above-mentioned states of isomerism, but are allotropic modifications of the same substance. Occasionally one and the same substance crystallizes in two distinct forms, its state is then described as one oi polymorphism [Tto’kv^.polus, many, morplie, form). Sulphur is polymorphous. It crystallizes by slow cooling in (1) prismatic crystals of sp. gr. 1.98, while in nature it occurs in (2) octahedra of sp. gr. 2.07. Melted and poured into water, sulphur takes up the form of (3) caoutchouc of sp. gr. 1.96. These differences warrant the statement that sulphur occurs in three distinct allotropic conditions. Cellulin or cellulose, the woody fibre of plants, familiar in the nearly pure state, under the forms of “ cotton-wool” ( Gossypium, B. P. and U. S. P., “ hairs of the seed of various species of Gossy- pium”), paper, linen, and pith, is another substance isomeric, probably polymeric, with starch. Lignin is a closely allied body, lining the interior of woody cells and vessels. By the action of nitric acid of various strengths on cellulin, peroxide of nitrogen {NO 2 ) is substi- tuted for one, two, or three atoms of hydrogen — mono-, di-, or tri- nitrocellulin being formed : — + HNO3 = + ‘*•0 Cellulin. Nitric acid. Mononitrocellulin. Water. CeH.oOs + 2HNO3 = «-{2n6,[o. + “.o Cellulin. Nitric acid. Dinitrocellulin. Water. CeH.oO, + 3HNO3 = c.l3Sb,}o>+ Cellulin. Nitric acid. Trinitrocellulin. Water. Trinitrocellulin is highly explosive gun-cotton ; dinitrocellulin is not sufficiently explosive for use instead of gunpowder ; mononitroceb lulin is scarcely at all explosive. 1'he three movable atoms of hy- drogen in cellulin may be displaced by bodies other than peroxide of nitrogen. Dinitrocellulin (Pyroxylin^ B. P.) may be prepared by the following process: Mix 5 fliiidounces of sulphuric acid and 5 of nitric in an earthenware mortar, immerse 1 ounce of cotton wool in the mixture, and stir it for three minutes with a glass rod so that it is thoroughly and uniformly 360 AMYLACEOUS AND SACCHARINE SUBSTANCES. wetted by the acids. Transfer the cotton to a vessel con- taining a considerable voliinie of water, stir it rapidly and well with a glass rod, decant the liquid, pour more water upon the mass, agitate again, and repeat the affusion, agita- tion, and decantation until the washing ceases to give a precipitate with chloride of barium. Drain the product on filtering paper, and dry in a water-bath. The Pyroxylin, U. S. P., is made by macerating half a troy ounce of cotton for fifteen hours in a mixture of four troy ounces of sulphu- ric acid and three and a half troy ounces of nitric, and washing as above. . Pyroxylin may also be made by soaking 7 parts of white faltering paper, which has been washed in hydrochloric acid and dried, in a mixture of 140 parts of sulphuric acid (sp. gr. 1.82) and 70 of nitric acid (1.37) for three hours, and well washing the product (Guichard). MononitTOcellidin and trinitrocellulin are insoluble in a mixture of alcohol and ether ; dinitrocelluUn or pyroxylin is soluble, the solution forming ordinary collodion [Collodium, B. P. and U. S. P.). The official proportions are 1 ounce of pyroxylin dissolved in a mix- ture of 36 fiuidounces of ether and 12 of rectified spirit. After digesting for a few days, the liquid is decanted from any insoluble matter and preserved in a well-corked bottle. It is “ a colorless, highly inflammable liquid with ethereal odor, which dries rapidly upon exposure to the air, and leaves a thin transparent film, insoluble in water or rectified spirit.” Flexible collodion ( Collodium Flexile, B. P., and U. S. P.) is a mixture of collodion (6 fiuidounces), Canada Balsam (120 grains), and castor oil (1 fluidrachm). QUESTIONS AND EXERCISES. ji i 709. How is wheat-starch or potato-starch isolated ? j 710. Define gluten and glutin, ! 711. Enumerate the proximate principles of wheaten flour. | 712. Is starch soluble in water ? ! 713. Which is the best chemical test for starch? j 714. Distinguish ph 3 ^sically between the varieties of starch. j 715. Into what compound is starch converted by heat ? j 716. AVhat occurs when a mixture of starch and water is allowed | to flow into hot diluted sulphuric acid ? j 717. If equal amounts of starch and water be heated, one contain- ing a small quantity of ground malt, what effects ensue ? ; 718. Write a short article on the chemistry of “ malting.” ! 719. What is the nature of gum arabic and how is it distinguished; from “ British Gum” ? 720. Explain isomerism, as illustrated by starch and dextrin. 721. Give examples of polymeric bodies. 722. State the formula of a body metameric with urea. 723. Define allotropy and polymorphism, giving illustrations. | SUGARS. 361 724. What form of cellulin is official ? 725. Mention the properties of the products of the action of nitric acid of various strengths on cellulin. 726. How is pyroxylin prepared. SUGARS. Cane-sugar, Ci,H220ii. Inverted-sugar, Grape-sugar, CgHi206,H20. Milk-sugar, Cj2H220ii,H20. Artificial formation of Grape-sugar from Cane-sugar . — Tests for Sugar . — Dissolve a grain or two of common cane-sugar in water. To a portion of this solution placed in a test-tube add more water, two or three drops of solu- tion of sulphate of copper, a considerable quantity of solu- tion of potash or soda (enough to turn the color of the liquid from a light to a dark-blue), and heat the mixture to the boiling-point; no obvious change occurs. To another portion of the syrup add a drop of sulphuric acid, and boil for ten or twenty minutes, then add the copper solution and alkali, and heat as before ; a yellowish-red precipitate of cuprous oxide (CU 2 O) falls. This test is exceedingly delicate. The above reaction is due to the conversion of the cane-sugar (C12H22O1J) into inverted-sugar, or Icevulose, CgHi20g (so-called be- cause its solution causes left-handed rotation of a ray of polarized light, cane-sugar having an opposite effect), and grape-sugar 0gHi20g, H2O, by the influence of the sulphuric acid, and to the reducing action of the inverted-sugar and the grape-sugar on the cupric solu- tion. The formation of a precipitate immediately, without the action of acid, shows the presence of the latter sugars — its formation only after ebullition with acid indicating, in the absence of starch or dextrin, cane-sugar. In this reduction process the sugar is oxi- dized and broken up into several substances ; the exact nature of the reaction has not been ascertained. Cane-sugar or sucrose [Saccharum Furificatum, B. P. and U. S. P.) is a frequent constituent of vegetable juices. Thus it forms the chief portion of cassia-pulp [Cassice Pulpa, B. P.), is contained in the carrot and turnip, but is most plentiful in the sugar-cane ; much, however, is now obtained from the sugar-maple and beetroot. On the evaporation of the juice, common brown or moist sugar crystal- lizes out ; this, by resolution, filtration through animal charcoal, evaporation to a strong syrup, and crystallization in moulds, yields the compact crystalline conical loaves known in trade as lump-sugar. From a slightly less strong syrup, slowly cooled, the crystals termed sugar-candy are deposited, white or colored according to the color of the syrup. 31 362 AMYLACEOUS AND SACCHARINE SUBSTANCES. Inverted Suyar or Lcevidose is uncrystallizable. It is found in the grape, fig [Ficus, B. P. and U. S. P.), cherry, and gooseberry; both grape-sugar and inverted sugar in the strawberry, peach, plum, etc. Grape-sugar or glucose (from ykvxv<;, glucus, sweet) is often seen in the crystallized state, in dried grapes or raisins and other fruits ; it is also the variety of sugar met with in diabetic urine. Its crys- talline character is quite distinct from that of cane-sugar, the latter forming large four or six-sided rhomboidal prisms, while grape-sugar occurs in masses of small cubes or square plates. Grape-sugar is also less soluble in water but more soluble in alcohol than cane-sugar. Laevulose is laBvogyrate, while Sucrose and Glucose possess right- handed rotation ; the latter twist a ray of polarized light from left to right, to an extent dependent on the amount of sugar present — a fact easy of application in estimating the amount of sugar in syrups or in diabetic urine. Both cane-sugar and grape-sugar yield alcohol and carbonic acid gas by fermentation, the cane-sugar probably always passing into grape-sugar before the production of alcohol commences. = 2C,H,HO + 2CO, ^ Grape-sugar, Alcohol. Carbonic acid gas. In bread-making, some of the starch is converted into dextrin, and this into sugar by the ferment. The above action then goes oq, the liberation of gas producing the rising or swelling of the mixture of flour, water, and yeast (dough) — the temperature to which the mass is subjected in the oven causing escape of alcohol, and further expansion of the bubbles of carbonic acid gas in every part of the now spongy loaf. The carbonic acid gas gradually evolved when flour is worked up for bread with a mixture of dry bicarbonate of sodium and tartaric acid (best preserved by previous admixture with dried flour and a little carbonate of magnesium) — haking-poivder — exerts similar influence. The least objectionable method of intro- f ducing carbonic acid gas, however, is that of Dauglish, whose patent Aerated Bread is made from flour by mere admixture with carbonic- acid water under pressure. On removal from the cylinder, the result- ing dough expands by the natural elasticity of the imprisoned car- bonic acid, and the bake-oven completes the process. The crumb of bread is official [Mica Fanis, B. P.). Milk-sugar or lactose (Gi.,H2^0i2) (Saccharum Lactis, B. P. and U. S. P), the sweet principle of the milk of various animals, is not susceptible of alcoholic or vinous fermentation; but it resembles j grape-sugar in reducing an alkaline solution of copper with precipi- | tation of suboxide. It is readily obtained from milk by adding a • few drops of acid, stirring, setting aside for the curds to separate, j filtering, evaporating the ivliey to a small bulk, filtering again if , necessary, and allowing to cool and crystallize. It usually occurs in i trade “ in cylindrical masses, two inches in diameter, with a cord or : stick in the axis, or in fragments of cakes — grayish-white, crystalline i on the surface and in its texture, translucent, hard, scentless, faintly | sweet, gritty when chewed.” It is soluble in 6 parts of cold and 3 • VARIETIES OF SUGAR. 363 of boiling water ; slightly soluble in alcohol ; insoluble in ether. Powdered milk-sugar is used in pharmacy as a vehicle for potent solid medicines. Action of Alkali on Sugar . — To a little solution of grape- sugar add solution of potash or soda, or solution of car- bonate of potassium, and warm the mixture; the liquid is darkened in color from amber to brown, according to the amount of sugar present. Tests. — The copper-reaction, the fermentation process, and the effect of alkalies form three good tests of the presence of grape- sugar, and, indirectly, of cane-sugar. A piece of merino or other woollen material, previously dipped in a solution of stannic chloride and dried, becomes of a brown or black color when dipped in a solu- tion of glucose and heated to about 300^ F. by holding before a fire. Sugar from Starch . — Boil the starch with a little water and a drop of sulphuric acid as for dextrin, but continue the ebullition for several minutes ; on testing a portion of the cooled liquid with iodine and another portion with the heated alkaline solution of a copper salt as described on page 361, it will be found that the starch has nearly all become converted into grape-sugar, or starch-sugar as it is sometimes termed. When made on a large scale, a warm (131 ° F.) mixture of starch and water of the consistence of cream is slowly poured into a boiling solution of one part of sulphuric acid in one hundred of water, the whole boiled for some time, the acid neutralized by chalk, the mixture filtered, the liquid evaporated to a thick S 3 U’up and set aside ; in a few da 3 ^s it crystallizes to a granular mass resembling honey. In this operation a small quantity of dextrin re- mains with the glucose; but if the process be conducted under pressure, conversion, according to Manbre, is com- plete. The sugar in fresh fruits is mainly cane-sugar ; but by the action of the acid, or possibly of a ferment in the juice, it is gradually con- verted into inverted sugar, a variety differing from cane-sugar in being uncrystallizable, and in having an inverted or opposite influ- ence on polarized light, twisting the ray from right to left (laevogy- rate, having laevo-rotation — hence sometimes termed levulose). Ripe Hips [Rosce Canince Fructus, B. P.) contain 30 per cent, of such sugar. Fruit-sugar, as gathered in the form of syrup by bees, is probably a mixture of these two varieties. It is gradually altered to a crystalline or granular mass of grape-sugar, as seen in dried fruits, such as Raisins {Uvce, B. P., Uva Fassa, tl. S. P.), and the Prune (Prunum, B. P, and U. S. P.) and in solidified honey [Mel, B. P. and U. S. P.). This, the common form of grape-sugar, is dex- trogyrate, and hence is sometimes termed dextrose, to distinguish it 364 AMYLACEOUS AND S A C 0 H A R I N E S U B S T A N C E S . from levulose. Honey often contains flocculent matters which cause it to ferment and yield mannite (Stoddart), alcohol, and acetic acid; hence for use in medicine it is directed [Mel Depuratum, B. P. and U. S. P.) to be clarified by melting and straining, while hot, through flannel previously moistened with warm water. A mixture of clari- fied honey 80 per cent., acetic acid 10 per cent., and water 10 per cent, is official under the name of Oxymel (from oxus, acid, and meli, honey). A similar mixture of honey with acetic acid containing the soluble portions of squill-bulbs (Scilla, B. P. and U. S. P.) is known as Oxymel of Squill [Oxymel Scilicet B. P.). Honey or sugar-cane are the bases of the official Confections. “ Honey Dew^' is a viscid saccharine matter occasionally met with on the leaves of the lime, maple, black alder, rose, and other trees. Sometimes it is sufficiently abundant to dry and fall on the ground, forming a veritable “ shower of manna.” It is a mixture of cane- sugar, inverted sugar, and dextrin. Barley sugar is made by simply heating cane-sugar till it fuses, a change from the crystalline to the uncrystallizable condition occur- ring. T reach ( Theriaca, B. P.), Molasses, [Syrupus Fuscus, U. S. P.), or Melasses (from Mel, honey), chiefly results from the applica- tion of too much heat in evaporating the syrups of the sugar cane ; it is a mixture of cane-sugar with uncrystallizable sugar and color- ing-matter. Liquorice-root [Glycyrrhizce Radix, B. P.) contains a considerable quantity of uncrystallizable sugar [Glycyrrhizin). Caramel . — Carefully heat a grain or two of sugar in a test-tube until it blackens ; the product is car'amel or burnt sugar (the Saccharum Ustum of pharmacy X. It is used as a coloring agent for gravies, confectioneries, spirits, and similar materials. Mannite (CgHj^Og). — Boil manna with alcohol, filter, and set aside ; mannite separates in colorless shining crystals or acicular masses, to the extent of from 60 to 80 per cent, of the manna. Manna, B. P. and U. S. P., is “ a concrete saccharine exudation from the stem of Fraxinus Ornus and F. rotundifolia ; it is ob- tained by making incisions in the stem of the trees.” It occurs in “ stalactiform pieces from one to six inches in length, and one or two inches in width, uneven, porous, and friable, curved on one side, of a yellowish-white color, with a faintly nauseous odor, and a sweetish taste.” It is also met with in celery, onions, asparagus, certain fungi and sea-weeds, occurs in the exudations of apple and pear trees, and is produced during the viscous fermentation of sugar. Mannite is an alcohol, the radical of which is sexivalent (CeUs)’'* 6110 (Wanklyn). It is closely related to the sugars, glucose becom- ing mannite by action of nascent hydrogen : — Glucose. -I- n, = Hydrogen. CbH„0, Maunite. Indeed, glucose itself is probably an alcohol of another radical | I THE G LUCOSIDES. 365 (C6Hg)'''6HO. Mannite does not undergo vinous fermentation in contact with yeast. It is soluble in 5 times its weight of cold water. Mticic Acid (H 2 C 6 HgOg) and Saccharic Acid (H 2 CgHgOg) are two isomeric bodies formed by the action of dilute nitric acid on gum, sugar, and mannite. QUESTIONS AND EXEKOISES. 727. How are cane-sugar and grape-sugar analytically distin- guished ? 728. Describe the methods of extracting and purifying cane-sugar. 729. Mention the chief sources of cane-sugar. 730. Give chemical explanations of the different processes of bread-making. 731. How is milk-sugar obtained, and in what respects does it differ from other sugar ? 732. By what process may starch be entirely converted into sugar ? 733. What is the difference between fruit-sugar and honey ? 734. What is Oxymel ? 735. Describe the effect of heat on cane-sugar. 736. Describe the source and character of manna. 737. Give the latest view of the constitution of mannite. 738. Whence are mucic and saccharic acids obtained ? THE GLUCOSIDES. Source . — The Glucosides are certain proximate vegetable princi- ples which, by ebullition with dilute acid, or other method of decom- position, take up the elements of water and yield glucose, accompa- nied by a second substance, which differs in each case according to the body operated on. Twelve of the glucosides are of pharmaceu- tical interest, namely : Amygdalin, Cathartic acid, Colocynthin, Convolvulin, Digitalin, Elaterin, Guaiacin, Jalapin, Salicin, San- tonin, Scammonin. Tannin, or tannic acid, is also a glucoside; it has been described among the acids. ^ Note on Nomenclature . — The first syllable of the names of gluco- sides and neutral principles generally are commonly given in allusion to origin ; the last syllable is m, which sufficiently distinguishes them as a class. Amygdalin (CyoH^^NO,^, 3H2O). — This is a white crystal- line substance, existing in the bitter {Amygdala Amara^ B. P. and U. S. P.), but not in the sweet almond {Amygdala Dulcis^ B. P. and U. S. P.). It is readil}^ extracted by alco- hol from the cake left when the fixed oil has been expressed 31 * 366 AMYLACEOUS AND SACCHARINE SUBSTANCES. from bitter almonds. From the concentrated alcoholic so- lution ether precipitates the amygdalin. Make an emulsion of two or three sweet almonds by bruising and rubbing them with water, and notice that it has no odor of essential oil of bitter almonds ; add a grain or two of amj^gdalin, an odor of essential oil of bitter al- monds is at once developed. Bruise two or three bitter almonds and rub with water ; the volatile oil is again de- veloped {Oleum Amy gdalse Amur se^ U. S. P.). Bitter Almond-water {Aqua Amygdalae Amarse^ U. S. P.) is made by filtering a mixture of 16 minims of the oil with 60 grains of carbonate of magnesium and 2 wine-pints of distilled water. The source of the hydride of benzoyl, or essential oil of bitter al- monds, in these reactions is the amygdalin, which, under the influ- ence of synaptase or emulsin, a ferment existing in both bitter and sweet almonds, splits up into the essential oil, hydrocyanic acid, and glucose : — -h = C,H,OH + HCN + Amygdalin. Water. Hydride of Hydrocy- Glucose. benzoyl. auic acid. As each molecule of amygdalin yields one of hydrocyanic acid, a simple calculation shows that 17 grains (mixed with emulsion of sweet almonds) will be required to form one grain of real hydro- cyanic acid, a quantity equivalent to 50 minims of the dilute hydro- cyanic acid of the British Pharmacopoeia. Test. — The reaction between synaptase and amygdalin is applica- ble as a test of the presence of one by the addition of the other, even when mixed with much organic matter. Cherry-Laurel-water (Aqua Laicrocerasi, B. P., by distillation with water from Laurocerasi Folia, B. P.) contains hydrocyanic acid derived from a reaction similar to, if not identical with, that just described. But the proportion of amygadalin or analogous body in cherry-laurel-leaves is most variable; hence the strength of the water is highly uncertain. The preparation is worse than useless. Caution. — Essential oil of almonds is highly poisonous. The purified oil or hydrate of benzoyl is almost innocuous ; it is obtained on distilling the crude oil with milk of lime and ferrous chloride. Artificial oil of bitter almonds or nitrobenzol (CgH5(N02)) when taken in quantity has been known to produce death. The presence of nitrobenzol in oil of bitter almonds is detected by adding a little of the oil to a mixture of zinc and diluted sulphuric acid, shaking well, setting aside for an hour or two, filtering off the clear liquid and adding a little chlorate of potassium; a violet color (actual mauve) is produced. Arbutin (OioHjgO,) is contained in the leaves of Arctostayliylos | uva ursi and Chimaphila umhellata. | Cathartic Acid. — “ The glucoside acid that now is known to I confer on the Senna of Alexandria (Seima Alexandidana, B. P.), I THE GLUCOSIDES. 367 Tinnevely [Senna Indica, B. P., Senna, U. S. P.), and probably on American Senna [Cassia Marilandica, U. S. P.), its purgative property, has been named by its discoverers (Dragendorf and Kubly) Cathartic acid. Its formula has been stated as Oj8oHj92N4SOg2, which, if true, accounts for its extreme stability. It is insoluble in water, strong alcohol, and ether, but enters readily into watery solu- tion when combined with alkaline and earthy bases, in which state it exists in senna. Its ammonium salts give brownish flocculent pre- cipitates with salts of silver, tin, mercury, copper, and lead. Anti- monial salts, tannin, yellow and red prussiates have no effect upon it. Alkalies, aided by heat, act destructively upon it. Boiled with a mineral acid it splits into a peculiar kind of glucose and an acid that has been named Cathartogenic ; its formula is said to be Ci32Hh 6^4S^44* ^he uatural cathartate occurring in senna is pre- pared by partially precipitating by strong spirit a water infusion of senna, concentrated to a syrupy state by evaporation in vacuo. The filtrate is now treated with a much larger bulk of absolute alcohol, and the precipitate thus obtained is purified by repeated solution in water and precipitation by alcohol. To obtain the pure acid, ad- vantage is taken of its colloidal properties ; the crude cathartate is dissolved in moderately strong hydrochloric acid, and subjected to dialysis on a diaphragm of parchment paper. The minimum dose of this pure acid was found to be about 1 ^ grain, which caused several stools with decided griping. “ The carthartic combinations that I have made are, the cathar- tate of ammonium, prepared from cathartate of lead by my original process, and the mixed cathartates, prepared according to Dragen- dorf’s method as modified by myself. Of the former nearly pure salt, I have found 3 J grains to purge fairly as to amount, but slowly as to time, and with considerable griping. Of the latter grains purged violently with much griping and sickness, which continued through the greater part of the day. It obviously would be improper to combine senna with any of its metallic precipitants, should such be desired, which is not likely. It is here satisfactory to observe that the cathartate of magnesium is soluble, and that the old-fashioned black draught agrees with new-fashioned science.” (Groves.) Buckthorn juice [Rhamni Succus, B. P.) owes its cathartic pro- perties to a substance apparently identical with cathartic acid. Chtratin. — The active principle of Chiretta ( Chirata, B. P. and U. S. P.) is said by Fluckiger and Hohn to be due to chiratin, a pale-yellow neutral substance allied to the glucosides. CoLOCYNTiiiN (C 5 gH 84023 ?). — Tliis substance is the active bitter and purgative principle of colocynth-fruit [Colocynthidis Ptdpa, B. P., Colocyntkis, U. S. P.) : it is soluble in water and alcohol, but not in ether. By ebullition with acids it furnishes glucose and a resinoid body. OoNvoLvuLiN. — See Jalapin. Digitalin (C27H45OJJ. — This is an active principle of the Foxglove [Digitalis.^ B. P.). Boil a grain of digitalin {Digitalimim^ B. P. and U. S. P.) with sulphuric acid for 368 AMYLACEOUS AND SACCHARINE SUBSTANCES. some time ; flocks of digitaliretin separate, and glucose may be detected in the liquid. + 2H,0 = + 2C,H„0, Digitalin. Water. Digitaliretin. Glucose. Properties. — Digitalin occurs “ in porous mammillated masses or small scales, white, inodorous, and intensely bitter, readily soluble in spirit, but almost insoluble in water and in pure ether, dissolves in acids, but does not form with them neutral compounds ; its solu- tion in hydrochloric acid is of a faint yellow color, but rapidly be- comes green. It leaves no residue when burned with free access of air. It powerfully irritates the nostrils, and is an active poison.” Process. — The official process for the preparation of digitalin con- sists in dissolving the glucoside out of the digitalis leaf [Digitalis Folia, B. P. and U. S. P.) by alcohol, removing the alcohol by distil- lation, dissolving the residue in water by the help of a small quantity of acetic acid, removing much of the color from the solution by ani- mal charcoal, neutralizing most of the acetic acid by ammonia, precipitating the digitalin by tannic acid (with which it forms an insoluble compound), washing the precipitate, rubbing and heating it with spirit and oxide of lead (which removes the acid in the form of insoluble tannate of lead), again decolorizing by animal charcoal, evaporating to dryness, washing out impurities still remaining by ether, and drying the residual digitalin. In this form digitalin is uncrystallizable. Pure Digitalin. — On treating commercial digitalin with chloro- form only an inert substance remains undissolved. The solution yields pure digitalin on evaporation ; it may be crystallized from spirit in radiating needles. (Nativelle.) The therapeutic effect of the pure substance is identical with the preparations of digitalis, but, as might be expected, more constant in its action and of course intensely powerful. Elatertn (C 2 oH 2 g 05 ). — Boil elateriiim (Elaterium^ B. P. and U. S. P.), the dried sediment from the juice of the squirting cucumber fruit {Echalii Fractus^ B. P.), in a small quantity of spirit of wine, and filter; fibrous and amyla- ceous matter remain insoluble, while elaterin and resin are dissolved. The filtrate, concentrated and poured into a warm solution of potash, yields, on cooling, crystals of elaterin, resin being retained by the alkali. It is purified l by recrystallization from spirit. Boil elaterium in dilute j sulphuric acid for an hour or two, filter, and test the clear i liquid for glucose; a reddish precipitate of cuprous oxide j falls. This reaction is readily obtained with elaterium, but not always with elaterin; hence probably^ the latter is | not a true glucoside. | Elaterin is the active principle of the so-called elaterium. Elate- \ rium occurs “ in light friable slightly incurved cakes, about one line ! THE GLUCOSIDES. 369 ( incli) thick, greenish-gray, acrid and bitter ; fracture finely granu- lar.” Good specimens of this drug should yield, according to the British Pharmacopoeia, not less than 20 per cent, of elaterin by the above process. Elaterium is sometimes adulterated with chalk and other substances. Guaiacin. — Resin of guaiaciim {Guaiaci Resina^ B. P. and U. S. P.), an exudation from the wood {Guaiaci Lig- num^ B. P. and IJ. S. P.) of Guaiacum officinale^ is probably a mixture of several substances, among ^vhich are Guaia- retinic acid (C2nH2604) (Hlasiwetz) and Guaiacin,^ a gluco- side. On boiling guaiacum-resin with dilute sulphuric acid for some time, glucose is found in the liquid, a green resinous substance {guaiaretin) remaining insoluble (Kos- niann). Most oxidizing agents, and even atmospheric air, especially under the influence of certain organic sub- stances, produce a blue, then green, and finally a brown color, when brought into contact with an alcoholic solution of guaiacum-resin. These effects are said to be due to three stages of oxida- tion (Jonas). They may be observed on adding the solu- tion to the inner surface of a paring of raw potato. Jalapin AND CoNVOLVULiN (Cg^H^gO^g). — Ac- cording to Keyser and Meyer, jalap-resin contains two distinct substances — convolvulin, chiefly obtained from Mexican male jalap, and jalapin, most largel}^ contained in the true jalap ; the former is soluble in ether, the latter insoluble. Boil jalap-resin with dilute sulphuric acid for some time and filter ; a substance, which is probably a tnre of jalapinol (€^3112403) and convolculinol (C^gHgoOg), separates ; and glucose may be detected in the clear liquid. (It is to be regretted that the authors transpose the above names, terming the old well-known jalapin convolvulin.) C,,H„0,, + 5H,0 ^ C,3H,,03 + 3C,H.A Jalapin. Water. Jalapinol. Glucose. Jolapic Acid, — This is contained in the portion of jalap- resin soluble in ether. It may also be obtained from jalapin by ebullition with alkalies : — 2C,„Hs„Oj5 + 3H,0 = Jalapin. Water. Jalapic acid. Jalap-resin {Jalapde Resina^ B. P. and IT. S. P.) is ob- tained by digesting and percolating jalap tubercles {Jalapa^ B. P. and U. S. P.) with spirit of wine, adding a little water, distilling off the spirit, pouring awaj^ the aqueous portion which contains much saccharine matter, and wash- 3t0 AMYLACEOUS AND SACCHARINE SUBSTANCES. ing and drying the residual resin. The tincture is some- times decolorized by animal charcoal, and the evaporated product sold as jalapin. Jalap-resin is insoluble in oil of turpentine ; common resin, or rosin, soluble. If the presence of the latter is suspected, the speci- men should be powdered, digested in turpentine, the mixture filtered, and the filtrate evaporated ; no residue, or not more than yielded by the turpentine itself, should be obtained. Saltcin (CigHjgO^). — This substance is contained in and easily^ extracted from willow-bark. Tests, — 1. To a small portion of salicin placed on a white plate or dish add a drop of strong sulphuric acid; a deep- red color is produced. 2. Boil salicin with dilute sulphuric acid for some time ; it is converted into saligenin (C 7 Hg 02 ) and glucose. + H,0 = C,H,0, + Salicin. Water. Saligenin. Glucose. Examine a portion of the solution for grape-sugar by the copper test. 3. To another portion of the liquid, carefully^ neutralized, add a persalt of iron ; a purplish-blue color is produced, due to the reaction of the saligenin and the ferric salt. 4. Heat a mixture of about 1 part of salicin, 1 of red chromate of potassium, of sulphuric acid, and 20 of water in a test-tube ; a fragrant characteristic odor is evolved, due to the formation of hydride of salicyl (C^H^O^H), an essen- tial oil identical with that existing in meadow-sweet {Spirse ulmaria) and in heliotrope. 2C,H,0, + O, = 2C,H,02H -f 2 H 2 O Saligenin. Oxygen. Hydride of Water. salicyl. Santonin ( 0 , 5 H,g 03 ). — This substance is a weak acid, insoluble in ammonia, but forming a soluble calcium salt. From a solution of santonate of calcium the santonin is precipitated by acids. Boiled for some time with dilute sulphuric acid it yields 87 per cent, of an insoluble resinous substance [santoniretin) and'glucose (Kosmann). Santonin [Santoninum, B. P. and U. S. P., and Trochiscz Santo- ninz, U. S. P.) is official. It is soluble in an aqueous solution of twice its weight of carbonate of sodium. Process. — The process for its preparation consists in boiling san- tomca, B. P. and U. S. P. (the unexpanded flower-heads of an undetermined species of Artemisia — A. cizia, U. S. P.), with milk of lime (whereby santonate of calcium is formed), straining, precipita- ting the santonin or santonic acid by hydrochloric acid (acetic acid, U. 8. P.), washing with ammonia to remove resin, dissolving in spirit and digesting with animal charcoal to get rid of coloring-matter, THE GLUCOSIDES. 371 setting the spirituous solution aside to deposit crystals of santonin, and purifying by recrystallization from spirit. (Mialhe). Saponin (Oi2H.,o07?) is a peculiar glucoside occurring in Soap- wort, the root of the common Pink, and many other plants : its solu- tion in water, even though very dilute, froths like a solution of soap. Pereira considered smilacin, one of the principles of the supposed activity of Sarsaparilla {Sarzce Radix, B. P., Sarsaparilla, U. S. P.), to be closely allied to, if not identical with, saponin. Saponin is also met with in the root of Polygala Senega {Senegce Radix, B. P., Senega, U. S. P.), though the active principle of senega is said to reside in polygalic acid, probably a glucoside de- rivative of saponin. ScAMMONiN — Boil resin of scaminony {Scam- monise Resina^ B. P. and U. S. P.) with dilute sulphuric acid for some time; glucose may then be detected in the liquid, a resinous acid termed scammoniol ?) being produced at the same time. Natural scammony (Scammonium, B. P. and U. S. P.) is an exu- dation from incisions in the living root [Scammonice Radix, B. P.) of Convolvulus Scammonia, It contains from 10 to 20 per cent, of gum. The British official resin of scammony contains no gum, and is made by digesting the root in spirit, adding water, distilling off the alcohol, and washing the residual resin with hot water till free from gum. The U. S. P. process consists in exhausting scammony in alcohol, recovering the latter by distillation, treating the residue with water, and drying the separated resin. Resin of scammony is soluble in all proportions in ether. Sul- phuric acid slowly reddens it. It is said to be liable to adulteration with resin of jalap, guaiacum-resin, and common rosin. Resin of jalap is insoluble in ether, guaiacum-resin is distinguished by the color tests mentioned under Gfuaiacin, and rosin by the action of sulphuric acid. QUESTIONS AND EXERCISES. 739. Define glucosides, ahd mention those of pharmaceutical in- terest. 740. Draw out an equation illustrative of the development of Oil of Bitter Almonds. 741. How much pure amygdalin will yield one grain of real hydro- cyanic acid ? 742. 'fo what does Cherry-Laurel-water owe activity ? Is the pre- paration trustworthy ? 743. Mention the active principle of Senna. 744. By what process is the glucoside of the purple foxglove pre- pared ? 372 ALCOHOL AND ALLIED BODIES. 745. State the circumstances under which Guaiacum-Eesin and Jalap-Eesin yield glucose. 746. Mention a test for guaiacum-resin. 747. How may the adulteration of jalap-resin by rosin be detected ? 748. Enumerate the tests for Salicin. 749. How^ is santonin officially prepared ? 750. Name sources of saponin. 751. What is the difference between Scammony and Eesin of Scammony ? 752. How would you detect resins of turpentine, guaiacum, or jalap, in resin of scammony ? ALCOHOL AND ALLIED BODIES. ALCOHOL. Formation of Alcohol. — Ferment two or three grains of sugar by dissolving in a test-tube full of water, adding a little yeast [Cere- visice Fermentiim, B. P., Fermeyitum, U. S. P.), or a piece of the so-called German or dried yeast, and setting the whole aside for j several hours in a warm place at a temperature of 70^ or 75^; car-j bonic acid gas is evolved, and, if the tube be inverted in a small dish } containing w^ater, may be collected in the upper part of the tube and ii subsequently tested : the solution contains alcohol. If the experi- 1 ment be made on larger quantities (four ounces of sugar, one of yeast, | and a pint of water) the fermented liquid should be distilled, one-half i being collected, shaken with a little lime, soda, or potash, to neutral- 1 ize any acetic acid, and decompose ethereal salts, and again distilled I till one-half has passed over ; the product is dilute spirit of wine. It may be still further concentrated or rectified by repeating this pro- j cess of f ractional distillation. ! Both cane-sugar and grape-sugar yield alcohol by fermentation, ! the cane-sugar probably always passing into grape-sugar before the I production of alcohol commences. | = 2C,H5H0 + 2CO, ! Grape-sugar. Alcohol. Carbonic acid gas. [ Traces of several other substances are simultaneously produced i [vide '' Kousel Oil” in Index). By this reaction are formed the spirit j of the v^ious kinds of wine, beer, and liqueurs, such as Orange AVine | { Vinvim Aiirantii, B. P.), made ‘‘ by the fermentation of a saccharine solution, to which the fresh peel of the bitter orange has been : added;” Sherry Wine [Vinum Xericum, B. P. and U. S. P.),the! fermented juice of the grape; Port Wine [Vinum Portense, U. S. P.), AVhiskey [8'piritus Frumenti, U. S. P.), containing from 48 to 56 - per cent, of pure alcohol; Spirit of My rci a or Bay Rum [Spiritus\ Myrcice, U. S. P.), prepared by distilling rum with leaves of Myrcia ' acris ; and others. Varieties of Alcohol. — The weak spirit concentrated by distilla-i tion till it contains 84 per cent, by weight of pure alcohol is an ALCOHOL. 673 ordinary article of commerce ; its specific gravity at 60^ is 0.8382. This is common Spirit of Wine, the Spiritus RectificaUis of the British Pharmacopoeia. Alcohol, U. S. P., has sp. gr. 0.835 ; Alco- hol Fortius, U. 8. P., sp. gr. 0.817. The official Proof SpiriP [Spiritus Tenuior, B. P.) contains 49 per cent, by weight of alcohol, and is made by diluting 100 volumes of Rectified Spirit with water until the well-stirred product measures 156 volumes. Sixty volumes of water will be required for this purpose, the liquids occupying less bulk after than before admixture. In the language of the Excise authorities the rectified spirit of the Pharmacopoeia would be de- scribed as “56 per cent, over proof” (56 per cent. 0. P.); that is 100 volumes contain as much alcohol as is present in 156 volumes of proof spirit. Obviously, proof spirit may be made by diluting with water rectified spirit of any other strength than that mentioned above. Thus 100 fluidounces of a spirit of “ seventy over proof” may be diluted to 170, or the same quantity of a spirit of “fifty over proof” may be diluted to 150, and so on. The specific gravity of proof spirit at 60^ is 0.920. [Alcohol Dilutum, U. S. P., has sp. gr. 0.941.) Empirical Formulce . — Compositiom, of Alcohol — Alcohol, by quantitative analysis, is found to contain the elements carbon, hydro- gen, and oxygen in the following proportions: — Composition of Alcohol. Carbon . . . 52.174 or -r- 12 = 4.348 or 2. Hydrogen . . . 13.043 or-;- 1= 13.043 or 6. Oxygen . . . 34.783 or 16 = 2.174 or 1. 100.000 From centesimal numbers a formula is obtained in the usual way. Thus, on dividing these figures by the atomic weights of the respec- tive elements (C = 12, II = 1, 0 = 16), and reducing the products to the simplest whole numbers, alcohol will be found to contain two atoms of carbon to every six of hydrogen and to every one of oxygen, and its possible or empirical formula to be C 2 HgO. Constitution of Alcohol. — There is good reason to believe that alcohol is the hydrate of a basylous radical ethyl (C^H^ or Et) ; hence we derive the rational formula O 2 H.HO or EtHO. Rational Formuloe. — Rational formulae are deduced by (1) ascer- taining how much of the substance will continue with, displace or play the part of, the atomic weight of a well-known elemenl^r radi- cal. When this method cannot be applied, or in confirmation of it, processes of (2) reduction, (3) oxidation, (4) substitution, etc., are employed. * Proof spirit is so termed from the fact that in olden times a proof of its strength was supposed to be afforded by moistening a small jfck. ^ quantity of gunpowder and setting light to the spirit: if it fired the powder it was said to be “ over proof if not, “ under proof.” The weakest spirit that would stand this test was what we should now describe as of sp. gr. 0.920. 32 374 ALCOHOL AND ALLIED BODIES. Salts of Ethyl . — Alcohol is, then, a body analogous in constitu- tion to hydrate of potassium (KHO) ; and there are other compounds of ethyl analogous in constitution to ordinary inorganic salts, such as those of potassium. The oxide of ethyl (Et^O) is common ether; the nitrite of ethyl (EtN 02 ) is the body which, dissolved in spirit of wine, constitutes “ sweet spirit of nitre the acid sulphate of ethyl (EtHS 04 ), or sulphethylic or sulphovinic acid, is a liquid met wdth in the preparation of ether. The iodide (EtI), hydride (EtH), ace- tate (EtA) and other salts are of considerable chemical interest, but not used in medicine. Absolute or Real Alcohol (C.^H^HO) may be prepared from spirit of wine by removing the water which the latter contains. This is accomplished, partially, by the agency of carbonate of potas- sium, and finally and entirely by recently burned quicklime. In operating on, say, one pint, 1 ^ ounce of dried carbonate of potas- sium is placed in a bottle that can be w^ell closed, and frequently shaken during two days with the spirit. Meanwhile, about half a pound of good quicklime, if not already at hand, is made from 10 or 11 ounces of slaked lime by heating to redness in a covered crucible for half an hour. The spirit having been decanted from the denser aqueous solution of carbonate of potassium and placed in a quart flask, retort, or tin can, the lime, as soon as cold, is added, and the whole occasionally shaken during a day. The vessel is now' placed in a saucepan or other bath containing w'ater, quickly connected with a condenser (in the case of the flask or can by a bent tube and cork previously prepared; for absolute alcohol must not be exposed to air, or w'ater in the form of moisture will be rapidly reabsorbed) and heat applied to the bath. Eejecting the first ounce or ounce and a half, as likely to contain traces of moisture absorbed from the air or apparatus, continue distillation until nothing more passes over, the W'ater in the bath being kept just below the boiling-point (about 200° F.). These details are those of the British Pharmacopoeia. Specific gravity 0.7938. Boiling-point 173.6. Tests . — There are no specific tests for alcohol w'hen mixed w'ith complex matters. It is, however, easily isolated and concentrated by fractional distillation, and is then recognizable by conjoint physi- cal and chemical characters. Thus its odor and taste are character- istic ; it is lighter than w'ater, volatile, colorless, and, when tolerably strong, inflammable, burning with an almost non-luminous flame ; it readily yields aldehyd (see below) and acetic ether [vide p. 268), each of w'hich has a characteristic odor ; lastly, in presence of hot acid, alcohol reduces red chromate of potassium to a green salt of chromium. According to Lieben 1 of alcohol in 2000 of w'ater can be detected by adding to some of the w'arme)i.diquid a little iodine, a few drops of solution of soda, again w'arming gently, and setting aside for a 1 time ; a yellow'ish crystalline deposit of iodoform (Clllg) is obtained, i Under the microscope the latter presents the appearance of hexago- j nal plates or six-rayed and other varieties of stellar crystals. i + 41^ + 6 NaIIO = CIII 3 + NaCHO.^ + 5NaI + 5U,0. j A L D E H Y D . 375 Otlier alcohols, aldehyds, gum, turpentine, sugar, and several other substances give a similar reaction. Tests of purity. — Oil of resin is precipitated on diluting spirit of wine with distilled water, giving an opalescent appearance to the mixture. The specific gravity should be 0.838. Fusel oil, aldehyd, and aldehydic acid are detected by nitrate of silver {vide Index, Alcohol,” test for purity of). Water in absolute alcohol maybe detected by adding to a small quantity a little highly dried sulphate of copper, which becomes blue (CuSO^.fiH.^O) if water is present, but retains its yellowish- white anhydrous character (CuSOJ if water be absent. Aldehyd (C2H^0). — Place together, in a capacious test- tube, or a flask, spirit of wine, black oxide of manganese, sulphuric acid, and water, and gently warm the mixture; aldeh3^d (aZcohol cZc/iy^Zrogenatus), a highly volatile liquid, is immediately formed, and its vapor evolved, recognized by its peculiar, somewhat fragrant odor. Adapt a cork and rather long bent tube to the, test-tube, and let some of the aldehyd slowly distil over into another test-tube, tlie condensing-tube being kept as cool as possible. Set the distillate aside for a day or two ; the aldehyd will have nearly all disappeared, and acetic acid be found in the tube. Test the exposed liquid by litmus paper; it will be found to have an acid reaction : make it slightly alkaline by a drop or two of solution of carbonate of sodium, then boil to remove an}’ alcohol and aldehyd present, add sul- phuric acid, and notice the characteristic odor of the acetic acid evolved. These experiments will enable the process of acetification described in connection with acetic acid to be more fully understood. Pure diluted alcohol is not oxidized by exposure to air ; but in presence of fermentive matter, or vegetable matter undergoing decay or change, it is oxidized first to aldehyd and then to acetic acid. In the above process the black oxide of manganese and sulphuric acid furnish nascent oxygen : — MnO^ + H 2 SO 4 = MnSO, + 0 -f B,0 Black oxide Sulphuric Sulphate of Oxygen Water, of manganese, acid, manganese. (atom). The nascent oxygen then acts on the alcohol, just as the oxygen of the air acts on the alcohol in fermented infusion of malt, beer, or wine, giving aldehyd : — C^H.O + 0 = C^H^O + H.O Alcohol. Oxygen Aldehyd. Water. (atom). The aldehyd rapidly, even when pure (more rapidly when impure), absorbs oxygen and yields acetic acid : — 2C2H,0 + O 2 = 2C.JI,0.2 Aldehyd. Oxygen. Acetic acid." 376 ALCOHOL AND ALLIED BODIES. Tests . — Aldeliyd heated with solution of potash gives a brownish-* yellow resinous mass of peculiar odor. Its aqueous solution reduces salts of silver, giving a mirror-like coating to the sides of a test-tube. Spirit of French Wine {Spiritus Vini Gallici, B. P. and U.S. P.) or Brandy is a colored and flavored variety of alcohol distilled from French wine. Its color is that of light sherry, and is derived from the cask in which it has been kept, but is commonly deepened by the addition of burnt sugar. Its taste is due to the volatile flavoring constituent of the wine, often increased by the addition of artificial essences. It should contain from 48 to 56 per cent, of alcohol. QUESTIONS AND EXERCISES. 753. Write a few sentences on the formation, purification, and concentration of alcohol, and explain the difference between Recti- fied Spirit, Proof Spirit, and Absolute Alcohol. 754. AYhat quantity of water must be added to one gallon of spirit of wine, 56 degrees over proof, to convert it into proof spirit. 755. To what volume must 5 pints of spirit of wine of 53 degrees be diluted before it becomes proof spirit ? — Ans. 7 pints, 13 ounces. 756. State the specific gravity of proof spirit. 757. Show how the formula of alcohol is obtained from its centesi- mal composition : — Carbon ' 52.174 Hydrogen 13.043 Oxygen 34.783 100.000 758. Give the formulae of some of the salts of ethyl. 759. By Avhat processes may pure hydrate of ethyl be obtained ? 760. Enumerate the characters of alcohol. 761. Mention a chemical test to distinguish rectified spirit from absolute alcohol. 762. From the formula of aldehyd calculate back its composition in 100 parts. 763. What is the relation of aldehyd to alcohol and to acetic acid? 764. AVhence is brandy obtained, and to what are due its color and flavor ? ETHER. Formula or (C.^H5)^0, or Et^O. Experimental Process . — Into a capacious test-tube put a small quantity of spirit of wine and about half its bulk of sulphuric acid, mix, and gently warm ; the vapor of ether, recognized by its odor, is evolved. Adapt a cork ET HYLIC ETHER. 377 and long bent tube to the test-tube aud slowly distil over the ether into another test-tube. Half the original quantity of alcohol now placed in the generating-tube will again give ether; and this operation ma}" be re])eated many times. On the lar'ge scale, and according to the following official process (jEther, B. P. and U. S. P.), the addition of alcohol, instead of being intermitting, is continuous, a tube conveying alcohol from a reservoir into the generating-vessel. Mix 10 fluidounces of sulphuric acid with 12 fluidounces of rectified spirit in a glass flask capable of con- taining at least two pints, and, not allowing the mixture to cool, connect the flask by means of a bent glass tube with a Liebig’s con- denser, and distil with a heat sufficient to maintain the liquid in brisk ebullition. If a thermometer be used the temperature maybe still more carefully regulated — between 284^ and 290° F. As soon as the ethereal fluid begins to pass over, supply fresh spirit in a continuous stream, and in such quantity as to about equal the volume of the fluid which distils. For this purpose use a tube furnished with a stopcock to regulate the supply, connecting one end of the tube with a vessel containing the spirit supported above the level of the flask, and passing the other end through the cork of the flask into the liquid. When a total of 50 fluidounces of spirit has been added, and 42 fluidounces of ether have distilled over, the process may be stopped. To partially purify the liquid, dissolve 10 ounces of chloride of calcium in 13 ounces of water, add half an ounce of lime, and agitate the mixture in a bottle with the impure ether. Leave the mixture at rest for ten minutes, pour off the light supernatant fluid, and dis- til it with a gentle heat until a glass bead of specific gravity 0.735 placed in the receiver begins to float. The ether and spirit retained by the chloride of calcium and by the residue of each rectification may be recovered by distillation and used in a subsequent operation. Explanation of Process .^ — On the addition of sulphuric acid to alcohol in equal volumes, one molecule of each react and give a molecule of sulphethylic acid and one of water : — EtHO -f = EtHSO, + H,0 Alcohol. Sulphuric Sulphethylic Water, acid. acid. More alcohol then gives ether and sulphuric acid by the reaction of one molecule of the alcohol on one of sulphethylic acid : — EtHO -f EtHSO, = Et20 + ^,^0, Alcohol. Sulphethylic Ether. Sulphuric acid. acid. The water of the first reaction and the ether of the second distil over, while the sulphuric acid, as fast as liberated, is attacked by alcohol and reconverted into sulphethylic acid : — EtHO -f H,SO, = EtHSO, = B,0 Alcohol, Sulphuric Sulphethylic Water, acid. acid. 32 * 378 ALCOHOL AND ALLIED BODIES. SO that the sulphuric acid originally employed finally remains in the retort in the form of sulphethylic acid. The effect, however, of a small quantity of sulphuric acid in thus converting a large quantity of alcohol into ether is limited, secondary reactions occurring to some extent after a time. Pro'perties . — Pure ether is gaseous at temperatures above 95^ F. ; hence the condensing-tubes employed in its distillation must be kept as cool as possible. At all ordinary temperatures it rapidly evapo- rates, absorbing much heat from the surface on which it is placed. A few drops evaporated consecutively from the back of the hand produce great cold ; if blowm in the form of spray, the cooling effect is so rapid and intense as to produce local anaesthesia. Its vapor is very heavy, more than twdce and one-half that of air and nearly forty times that of hydrogen ; 0^1110= 74; or as one to 37). In a still atmosphere therefore it will flow a considerable distance along a table or floor before complete diffusion occurs ; the vapor is also highly inflammable ; hence the importance of keeping candle and other flames at a distance during manipulations wdth ether. Purification, — To imitate the process of partial purifica- tion above described, add to the small quantity of ether obtained in the foregoing operation a strong solution of chloride of calcium and a little slaked lime ; the latter absorbs any sulphurous acid that may have been produced by secondaiy decompositions, while the former absorbs water ; on shaking the mixture and then setting aside for a minute or two, the ether will be found floating on the surface of the solution of chloride of calcium. This ether, redistilled until the distillate has a sp. gr. not higher than 0.735 (0.750, U. S. P.) and boiling-point not higher than 105*^ F., is the ether of ihe British Pharmacopoeia. It still contains about 8 per cent, of alcohol. I’he latter may be removed by W'ell shaking the ether with half of its bulk of water, setting aside, separating the floating ether and again shaking it with w^ater ; alcohol is thus washed out. This w^ashed ether containing w^ater (for w’ater and ether are to some extent soluble the one in the other; 50 measures agitated with an equal volume of water are reduced to 45 by an | absorption of 10 per cent.) is next placed in a retort wdth solid chlo- | ride of calcium and a little caustic lime, and once more distilled; | pure dry ether [jEtlier Purus, B. P., JEther Fortior, U. S. P.) ! results. Sp. gr. not exceeding 0.720 (0.728, U. S. P.). | Spiritus jFtheris, B. P., is a mixture of common ether {jFther, \ B. P.) with twice its bulk of rectified spirit. | NITROUS ETHER, OR NITRITE OF ETHYL. Formula EtNOg. j Process , — To a third of a test-tubeful of rectified spirit i add about a tenth of its bulk of sulphuric acid, rather more : I NITROUS ETHER. 379 of nitric acid, and some copper-wire or turnings, and warm tlie mixture as soon as ebullition commences, the vapor of nitrous ether is evolved, recognized by its odor. A long bent tube, kept cool, may be adapted by a perforated cork to the test-tube, and thus a few drops of impure nitrous ether be condensed and collected. The above process conducted on a larger scale, with definite quantities of materials, temperature regulated by a thermometer, and a well-cooled condenser, is the official (Redwood’s) process for the preparation of a concentrated solution of nitrous ether in spirit ; di- luted with nearly three times its bulk of rectified spirit it forms the “ sw^eet spirit of nitre” [Spiritus ^Jtheris Nitrosi, B. F. and U. S. P.) of pharmacy. “ Take of Nitric Acid 3 fluidounces, Sulphuric Acid 2 fluidounces, Copper, in fine wire (about No, 25) 2 ounces, Rectified Spirit a sufficiency. “To one pint of the spirit add gradually the sulphuric acid, stir- ring them together ; then add, in the same way, two and a half ounces of the nitric acid. Put the mixture into a retort or other suitable apparatus, into which the copper has been introduced, and to which a thermometer is fitted. Attach now an efficient condenser, and, ap- plying a gentle heat, let the spirit distil at a temperature commenc- ing at 170^ and rising to 175^, but not exceeding 180^, until 12 fluidounces have passed over and been collected in a bottle kept cool, if necessary, with ice-cold water ; then withdraw the heat, and, having- allowed the contents of the retort to cool, introduce the remaining half ounce of nitric acid, and resume the distillation as before, until the distilled product has been increased to 15 fluidounces. Mix this with tw^o pints of the rectified spirit, or as much as will make the product correspond to the tests of specific gravity and percentage of liquid separated by chloride of calcium (vide infra). Preserve it in well-closed vessels. Disregarding secondary products (including much aldehyd), the following equation probably represents decompositions that occur in the operation. The main point in the reaction is the reduction of the nitric to the nitrous radical by the indirect a^gency of the copper. EtHO 4- HNO3 + + Cu = EtNO^-P + CuSO^ Alcohol. Nitric Sulphuric Copper. Nitrous Water. Sulphate of acid. acid. ether. copper. Properties. — Spirit of Nitrous Ether “is transparent and nearly colorless, with a very slight tinge of yellow, mobile, inflammable, of a peculiar penetrating apple-like odor, and sweetish, cooling, sharp taste. Specific gravity, 0.845. It effervesces feebly, or not at all, wdien shaken with a little bicarbonate of soda” (showing absence of appreciable quantities of free nitrous, acetic, or other acids). The aldehyd in it may be detected by the potash test (see page 376). Test, — The nitrous radical may be detected by adding sulphate of 380 ALCOHOL AND ALLIED BODIES. iron and sulphuric acid to some of the spirit of nitrous ether, a brown or black compound being produced, already explained in connection with nitric acid (p. 256). Test of Strength. — To some of the official Spirit of Nitrou« Ether add twice its bulk of a saturated solution of chloride of calcium and mix the liquids ; on setting aside, nitrous ether will rise to the surface. If the spirit of nitrous ether be of official strength, not less than 2 per cent, of its vol- ume will thus separate, indicating the presence of 10 per cent, of the ether, 8 per cent, being said to be still in solu- tion. A graduated tube is obviously most convenient for this purpose. Spiritiis jTJtheris Nitrosi^ U. S. P., has the specific gravity 0.837, and contains five per cent, of nitrous ether. Iodide of Ethyl (EtI) may be prepared by mixing amorphous phosphorus with absolute alcohol and then add- ing iodine. 5EtHO + PI3 = 5EtI + H,PO, + H^O Alcohol. Iodide of Iodide of Phosphoric Water, phosphorus, ethyl. acid. The reaction at first proceeds rapidly, and is complete after the mixture has been set aside for a few hours. The iodide of ethyl may then be isolated by careful distillation, freed from any excess of iodine by washing with a very small quantity of solution of potash or soda, washed with water, dried over chloride of calcium, and again distilled. It should be kept in a dark place, as light favors decompo- sition and liberation of iodine. Ethyl. — This gaseous radical, (0.^115)2 or Et^, is obtained ! on digesting together at about 250° F., in a strong sealed tube, dry freshly granulated zinc with iodide of eth}’! (Frankland). Zn + 2EtI = Znl, + Et, Zinc. Iodide of Iodide of Ethyl, ethyl. zinc. On cautiousl}' opening the tube the ethyl escapes, and may be ignited or collected over water. There remains with the iodide of zinc a body termed by Frankland zinc-ethyl | (ZnEtJ ; it is a spontaneously inflammable liquid, but may j easily be distilled and otherwise manipulated if a few sini- i |)le precautions be observed. If water be allowed to flow > down the tube, the solid compound of iodide of zinc and i zinc-ethyl will be decomposed, a gas, hydride of ethyl 1 OTHER ALCOHOL RADICALS. 381 (Etll), resulting, which also may be inflamed or collected over water ; — ZnEt^ + = Zn2HO + 2EtH. QUESTIONS AND EXERCISES. 765. Describe the official process for the preparation of Ether, giving equations. 766. Offer a physical explanation of the mode of producing local anaesthesia. 767. How is commercial ether purified ? 768. Explain Redwood’s process for the preparation of “sweet spirit of nitre.” 769. Give the properties of spirit of nitrous ether. 770. By what method is the strength of “sweet spirit of nitre” estimated ? 771. How is iodide of ethyl made ? 772. Adduce evidence of the existence of ethyl. OTHER ALCOHOL RADICALS AND THEIR SALTS. What has been stated concerning the chemistry of ethyl and its compounds may be applied to other radicals known to exist, some of the compounds of each of which are of common occurrence. These basylous radicals are closely related to each other, to hydrogen, and to the metals. Starting from hydrogen, their formulae may be built up by successive additions of OH 2 , thus : — Hydrogen . . . H Methyl . . . CH„ or Me Ethyl . . . or Et Propyl (or Trityl) . . . . . . O 3 H,, or Pr Butyl (or Tetryl) . . . . . . C,H„ or Bu Amyl . . . C,H„, or Ay Caproyl (or Hexyl) . . . or Cp The above list is an illustration of an homologous series (from o/x 6 j, homos, the same, and T^oyo^, logos, description) of compounds. It will be observed that the relation of the number of hydrogen atoms to carbon is twice as many with one added ; hence the series is often termed the C,,H 2 „+i series {n = any number). The oxides of these radicals are known as ethers, their hydrates alcohols, their compounds with the acetic and similar acidulous radicals ethereal salts. Every alcohol furnishes a body corresponding to the aldehyd of spirit of wine, the class being termed aldehyds ; each also yields an acid cor- 382 ALCOHOL AND ALLIED BODIES. responding with acetic acid. Any one of these classes constitutes an homologous series. Or, taking the hydride, oxide, hydrate, acid, of any single radical, we get a heterologous (EVfpo^, heteros, another) ' series of compounds. Hydride of methyl (MeH or CHgH) is ordi- nary marsh-gas, fire-damp, or light carhuretted hydrogen ; it is a diluent or non-luminiferous constituent of ordinary coal-gas to the extent of 30 to 40 per cent. ;* formic acid, the acid of the methyl series ; butyric acid, the acid of the butyl series ; sulphocyanate of butyl, the essential oil of horseradish ; valerianic acid, the acid of the amyl series. Homologous and Heterologous Series of the Radicals, Radicals. Hydrides. Oxides (or ethers). Hydrates (or alco- hols). Aldehyds. Acids. (C H3 ), (CA ), (C 3 H, ), (C.H, ), etc. C H, H O 3 H 5 H C 3 H, H cah OaHnH etc. (C H3 ),0 (CA (C 3 H, )30 (O.H, )30 (C 5 H „)30 etc. C H 3 HO C2H5 HO CgH, HO C.IIg HO C 5 H,,H 0 etc. 0 H, 0 ? C 3 H; 0 0,H3 0 c;h3 0 O5H30O etc. 0 H.3 0.3 C3H, 0.3 C3H3 0.3 C3H3 0.3 C5H.0O3 etc. QUESTIONS AND EXERCISES. 773. Mention several radicals homologous with ethyl, and give their formulae. 774. Define ethers, hydrides, alcohols, ethereal salts, aldehyds. 775. What is the difiPerence between homologous and heterologous series ? 776. Give the systematic name of fire-damp. 777. Enumerate the chief constituents of coal-gas. 778. State the formulae of formic, butyric, and valerianic acids. 779. Write the formulae of butyl, its hydride, ether, alcohol, alde- hyd, and acid. * Coal-gas . — The other diluents, or vehicles for the illuminating constituents, of coal-gas are hydrogen (40 to 50 per cent.) and carbonic oxide (6 to 7 per cent). The illuminating constituents are olefiant gas (p. 394) and its liornologues, existing to the extent of from 5 to 7 per cent. The impurities are nitrogen, air, carbonic acid, bisulphide of carbon CSg (a volatile liquid easily made from its elements), and other badly smelling sulphur compounds. Upwards of fifty distinct 1 cliemical substances have been obtained from the solid, liquid, and | gaseous products of the destructive distillation of coal. ! MET HYLIC ALCOHOL. 383 MYTHYLIC ALCOHOL. Methylic Alcohol (CH^HO, or MeHO), Wood-Spirit, or Py- ROXYLic Spirit, or Wood-Naphtha, is a product of the destructive distillation of wood. Spirit of wine containing 10 per cent, of wood- spirit constitutes ordinary methylated spirit, a spirit issued duty free, for the use of manufacturers, the methylic alcohol not interfering with technical applications. From its nauseous taste and odor, how- ever, it cannot take the place of gin, brandy, or other spirit ; hence, while industry is benefited, intemperance is discouraged and the revenue not injured. Detection of Methylic Alcohol in presence of Ethylic Alcohol . — Three or four methods have been proposed for the detection of methylated spirit in various liquids ; that open to least objection is by J. T. Miller. For the applica- tion of the test to tinctures and similar spirituous mix- tures, some of the spirit is first separated by distilling off a drachm or so from about half an ounce of the liquid placed in a small flask or test-tube having a long bent tube attached. Into a similar apparatus put 30 grains of pow- dered red chromate of potassium, half an ounce of water, 25 minims of strong sulphuric acid, and 30 or 40 minims of the spirit to be tested. Set the mixture aside for a quarter of an hour, and then distil nearly half a fiuidounce. Place the distillate in a small dish, add a very slight excess of carbonate of sodium, boil down to about a quarter of an ounce, add enough acetic acid to impart a distinct but feeble acid reaction, pour the liquid into a test-tube, add a grain of nitrate of silver dissolved in about 30 drops of water, and heat gently for a couple of minutes. If the liquid then merely darkens a little, but continues quite translucent, the spirit is free from methylic alcohol ; but if a copious precipitate of dark-brown or black metallic silver separates, and the tube, after being rinsed out and filled with clean water, has a distinct film of silver, which appears brown by transmitted light (best seen by holding it against white paper), the spirit is methylated. Explanation .— test depends for its action on the reducing- powers of formic acid. In the above operation the ethylic alcohol becomes oxidized to acetic acid (the natural acid of the ethyl series), which does not reduce silver salts, a minute quantity only of formic acid being produced, while the methylic alcohol yields formic acid (the natural acid of the methyl series) in a comparatively large quantity. Aldehyd, which is also a reducing agent, is simultaneously produced, but removed in the subsequent ebullition with carbonate of sodium. 884 ALCOHOL AND ALLIED BODIES. Methylated Sweet Spirit of Nitre . — The preparation of spirit of nitrous ether from methylated spirit is illegal in Great Britain, but, nevertheless, occasionally practised. For the detection of methylic alcohol in this liquid, Mr. Miller suggests the following modification of the above process. Shake about an ounce of the sample with 20 or 30 grains of anhydrous carbonate of potassium, and, if needful, add fresh portions of the salt until it ceases to be dissolved, then pour off the supernatant spirit. This serves to neutra- lize acid and to remove water, in which some samples are remarkably rich. Introduce half a fluidounce of the spirit into a small flask; add 150 grains of anh 3 xlrous chloride of calcium in powder, and stir well together; then, having connected the flask with a condenser, place it in a bath of boiling water, and distil a fluidrachm and a half, or con- tinue the distillation until scarcely" an^^thing more comes " over. The operation is rather slow, but needs little atten- \ tion, and should be done thoroughl>^ The distillate con- | tains nearly the whole of the nitrous ether and other i interfering substances. Now add to the contents of the I flask a fluidrachm of water, and draw over the half drachm | of spirit required for testing. Add to it the usual oxidiz- j: ing solution composed of 30 grains of red chromate of ji potassium, 25 minims of strong sulphuric acid, and half 1 an ounce of water; let the mixture stand a quarter of an i hour, then distil half a fluidounce. Treat the distillate with j a slight excess of carbonate of sodium, boil rapidl}^ down to two fluidrachms, and drop in, cautiousl>^, enough acetic acid to impart a faint acid reaction; pour the liquid into a test-tube about three-quarters of an inch in diameter; add two droi)S of diluted acetic acid, and one grain of nitrate of silver in half a drachm of pure water; applj^ heat, and boil gentl^y for two minutes. If the spirit is free from methylic alcohol the solution darkens and often assumes ; transiently a purplish tinge, but continues quite translu- i cent, and the test-tube, after being rinsed out and filled I with water, appears clean or nearly so. But if the spirit j contains only 1 per cent, of methvlic alcohol the liquid ! turns first brown, then almost black and o[)aque, and a film i of silver, which is brown bj" transmitted light, is deposited on the tube. When the sample is methylated to the extent of 3 or 4 per cent., the film is sufficient!}^ thick to form a brilliant mirror. To insure accuracy, the experiments | should be performed b}^ davlight. I CHLOROFORM. 385 CHLOROFORM. Formula CHCI3. Process. — Should the necessary appliances be at hand, a small quantit 3 ^ of this liquid may easily be prepared by the official process. One fluidounce and a half of spirit and 24 of water are placed in a retort or flask of at least a quart capacity ; 8 oz. of chlorinated lime and 4 of slaked lime are added, the vessel connected with a condenser, and the mixture heated until distillation commences, the source of heat then being withdrawn. The condensed liquid should fall into a small flask containing water, at the bot- tom of which about a drachm of chloroform will slowly collect. Explanation of Process. — The hypochlorite of calcium (Ca2C10) believed to be present in the chlorinated lime (see remarks in con- nection with hypochlorous acid) readily yields up oxygen and chlo- rine to organic substances, the calcium being liberated as hydrate, 4(Ca2C10) + 4H,0 = 4(Ca2H0) + 20,4-4Ck. The alcohol used in making chloroform is thus reduced first to aldehyd : — 2G,E,0 + 02 = 2C2H,0 + 2 H 2 O Alcohol. Oxygen. Aldehyd. Water. The action of chlorine on aldehyd then probably gives chloral (chlor-aldehjd ) : — C^H.O + 3CI2 = C2HCI3O + 3HC1 Aldehyd. Chlorine. Chloral. Hydrochl. acid. The hydrochloric acid being at once neutralized by some of the liberated hydrate of calcium to form chloride of calcium and water, more freed hydrate of calcium and chloral give formate of calcium and chloroform. 2C._,HCl30 + Ca2H0 == Ca2CH02 + 2CHCI3 Chloral. Hydrate of Foimate of Chloroform, calcium. calcium. Or, neglecting the probable steps in the process, and regarding only the materials and the products, 4 molecules of alcohol and 8 of hypochlorite of calcium give 2 of chloroform, 3 of formate of cal- cium, 5 of chloride of calcium, and 8 of water, thus : — 4C.2H,0 + 8CaCl20.2 = 2CHCl3+ 3(Ca2CH02) + 5CaCl2+ SH^O Alcohol. Hypochlorite Chloroform. Formate of Chloiide of Water, of calcium. calcium. calcium. The hydrate of calcium placed in the generating-vessels is not es- sential, but is useful in preventing secondary decompositions, the hydrate of calcium obtainable from the reaction being insufficient for this purpose. Constitution. — Chloroform is sometimes considered to be the chlo- 33 38 G ALCOHOL AND ALLIED B 0 Jl ES. ride of a trivalent radical methenyl (CH), the first member of a series Glycerine is the hydrate of another member— ceryl or propenyl, O3H5 (p. 394 ). Chloroform may also be regarded as the chloride of dichlor-methyl ; it may be formed from methylic compounds, thus : — 2 CH ,0 + 2(CaCl2,Ca01,02 = 2CHCI3 + CaCl, 3 CaO + 3H3O Methylic Chlorinated Chloroform. pxychloride of Water. alcohol. lime. calcium. Chlorine converts it into tetrachloride of carbon, completing a series of substitution products of chloride of methyl. C H H H Cl Chloride of methyl. c H H Cl Cl Chloride of mono-chlor- methyl. c H Cl Cl Cl Chloride of di-chlor- methyl. .1 cn 01 y 01 or 001, 01 Chloride of Tetrachloride tri-chlor- or of methyl carbon. The chloride of mono-chlor-methyl, under the name of dichloride of methylene, has been used as an anaesthetic. It may be obtained by the action of nascent hydrogen on chloroform. Chloroform is purified by shaking it with pure sulphuric acid containing no trace of nitric acid, which chars and removes hydro- carbons, but does not affect chloroform. It is freed from any trace of acid by agitation with carbonate of sodium and from moisture by distillation with lime. Properties. — The sp. gr. of purified chloroform is 1.497 ( 1.480 U. S. P.). It readily and entirely volatilizes with characteristic odor at common temperatures. It has a sweetish taste, is limpid, color- less, soluble in alcohol and ether, and slightly in water, but burns with a sluggish green smoky flame. Iodoform [lodoformum, U. S. P.) analogous in constitution to chloroform, the iodine taking the place of the .chlorine (CHI3), is prepared by mixing in a retort 2 parts of carbonate of potassium, 2 parts of iodine, 1 part of alcohol, and 5 of water, heating till color- less, and then pouring into a beaker and allowing to settle. The Iodoform is deposited in yellow scales, which are collected on a filter, washed thoroughly with water and dried between filtering paper. Iodoform appears in the shape of yellow, shining six-sided scales with a saffron-like odor ; is volatile at ordinary temperatures, and at a temperature above 250 ^ is decomposed, giving off violet vapors. Almost insoluble in water, but more so in alcohol, ether, and the fixed and volatile oils. CHLORAL AND CHLORAL HYDRATE. Process. — Pass a rapid stream of dry chlorine "into pure absolute alcohol so long as absorption occurs. During the first hour or two the alcohol must be kept cool, afterwards gradually warmed till ulti- mately the boiling-point is reached. The preparation of a consider- able f|uantity occupies several days. The crude product is mixed 1 Avith three times its volume of oil of vitriol and distilled, again mixed . CHLORAL. 38T / with a similar quantity of oil of vitriol and again distilled, and finally rectified from quicklime. The formation of chloral would at first sight seem to be due to the production from the alcohol (C.2HgO) of aldehyd (OgH^O), through the removal of hydrogen by the chlorine, and the substitution of chlorine for hydrogen in the aldehyd (02H^O) with formation of chlor-aldehyd or chloral (O^HCl^O). But the reactions are far more complicated, being somewhat as follows. Aldehyd and hydrochloric acid are first formed ; these with some of the alcohol give monochlo- rinated ether, j- 0 , which with more chlorine yields tetra- 0 H 1 chlorinated ether, GMCl ( Og, and this in presence of water fur- nishes chloral, some alcohol, and some hydrochloric acid (Wurtz and Vogt). Properties , — The formula of chloral is C^HClgO. It is a colorless liquid, of oily consistence. Sp. gr. 1.502. Boiling- point 201.2. Its vapor has a penetrating smell, and is somewhat irritating to the eyes. Mixed with water heat is disengaged, and solid white, crystallizable, hydrous clilo- ral {Chloral,^ U. S. P.), or what is more generally, though somewhat irregularly, termed chloral hydrate (C^HCl.^O, H2O) results. The latter fuses at 110.8 and boils at 293° F. It sublimes as a white crystalline powder. Both chloral and chloral hydrate are soluble in water, alcohol, ether, and oils. The aqueous solution should be neutral, and give no reaction with nitrate of silver. Chloral is said sometimes to undergo a spontaneous change into an opaque white isomeric modification, insoluble in water, alcohol, or ether, but convertible by prolonged contact with water or by distillation into the ordinary condition. By action of weak alkalies chloral first yields formiate of the alkali-metal and chloroform: — C2HCI3O + KHO = KCHO2 + CHCI3. Chloral, or rather strong aqueous solution of chloral hy- drate (3 in 4), injected beneath the skin ^fields nascent chloroform by action of the alkali of the blood, and pro- duces narcotic effects (Liebreich, Person ne). Chloroform itself admits of similar hypodermic use (Richardson). If administered by the stomach, thirty to eighty grains of solid hydrate are required. The final products of the re- action of the chloroform and blood are formiate and chloride of sodium. A spirituous solution of potash effects the same transformation. CHCI3 + 4KHO = KCHO2 + 3KC1 -f 2H2O 388 ALCOHOL AND ALLIED BODIES. Solution of ammonia and moist hydrate of calcium, as well as weak solutions of fixed alkalies, convert hydrate of chloral into formiate of the metal and chloroform. The reaction with the slaked lime being especially definite and complete (Wood), it may be employed in ascertaining the richness of a sample of commercial chloral hydrate in chemically pure chloral hydrate. 2( C,HCl30, 11,0) + Ca2H0 = 2CHCI3 + Ca2CH0, + 2H,0. From the foregoing equation and molecular weights it is obvious that 100 grains of hydrate of chloral, if quite dry, will yield by distillation with lime and a little water (in a small flask and long bent tube kept cool by moistened paper) t2.2 grains of chloroform, by weight, or (the sp. gr. of chlo- roform being taken at 1.497) 47.56 grains by measure, or about 52 minims. Pure Chloral Hydrate. — Liebreich, who first proposed the use of chloral hydrate, gives the following as the char- acteristics of a pure article: Colorless, transparent. Does not decompose by the action of the atmosphere, does not leave oily spots when pressed between blotting-paper, affects neither cork nor paper. Smells agreeably aromatic, but a little pungent when heated. Taste bitter astringent, slightly caustic. Seems to melt on rubbing between the fingers. Dissolves in water like candy without first form- ing oily drops. Dissolves in bisulphide of carbon, petro- leum, ether, water, alcohol, oil of turpentine, etc. Boiling- point 203° to 205° F. Distilled with sulphuric acid, the chloral should pass over at 205° to 207° F. Melting-point 133° to 136° F. Gives no chlorine reaction on treating the solution in water (acidulated b3’' nitric acid) with nitrate of silver. Impure Chloral Hydrate. — Yellowish, cloud3^ Decom- poses ; leaves spots by pressing between blotting-paper; decomposes corks and paper of the packing. Smells pun- gent and irritating ; on opening the bottles sticky and often emits fumes. Taste strongly caustic. With water forms oily drops or is partially insoluble. Boils at a higher tem- perature. On treating it with sulphuric acid turns brown, with formation of hydrochloric acid. Gives chlorine reac- tion on treating the solution in water (acidulated by nitric acid) with nitrate of silver. AMY Lie ALCOHOL. 389 Alcoholates of chloral are obtained on combining alcohols with chloral. Bromal (C2HBr30), hydrate of bromal (C2HBr30, H^O), alcoholates of bromal produced when bromine in- stead of chlorine attacks alcohol. AMYLIC ALCOHOL. Amylic Alcohol [Alcohol Amylicum^'B. P. and U. S. P.) (C5HH HO, or AyHO) is a constant accompaniment of ethylic or common alcohol (O2H5HO, or EtHO) when the latter is prepared from sugar which has been derived from starch ; hence the name, from amylum starch. The sugar of potato-starch yields a considerable quantity ; hence the alcohol is often called potato-oi'L It is also termed f ousel- oil, or fusel-oil (from ^vco, phuo, to produce), in allusion to the cir- cumstance that the supposed oil is not simply educed from a sub- stance already containing it, as is usually the case with oils, but is actually produced during the operation. It was described as oil pro- bably because it resembled oil in not readily mixing with water ; but it is soluble to some extent in water, and is a true spirit, homologous with spirit of wine. It often contains variable proportions of pro- pylic, butylic, and caproylic alcohols. See also Valerianic Acid. Amylic alcohol is “ a colorless liquid with a penetrating and op- pressive odor, and a burning taste. When pure its specific gravity is 0.818 ; boiling-point 279 ^. Sparingly soluble in water, but soluble in all proportions in alcohol, ether, and essential oils. Exposed to the air in contact with platinum-black, it is slowly oxidized, yielding valerianic acid.” Two allotropic varieties of amylic alcohol exist, one dextro-rotating a polarized ray. Acetate of Amyl (C5HJ1C2H3O2, or AyA). To a small quantity of amylic alcohol in a test-tube add some acetate of potassium and a little sulphuric acid, and warm the mixture; the vapor of acetate of amyl is evolved, recog- nized by its odor, which is that of the jargonelle pear. If a conden sing-tube be attached, the essence may be distilled over, washed by agitation with water to free it from alcohol, and separated by a pipette. KA -f AyHO + H2SO, == AyA + KHSO, -+- H2O Acetate of Amylic Sulphuric Acetate of Acid sulphate Water. potassium. alcohol. acid. amyl. of potassium. Fruit- Essen ces. Acetate of amyl, prepared with the proper equivalent proportions of constituents as indicated by the above equation, is largely manu- factured for use as a flavoring agent by confectioners. Valerianate of amyl (Cj^Hi^C5H902) is similarly used under the name of apple-oil. Butyrate of ethyl (O2M5C4H7O2) closely resembles the odor and 390 ALCOHOL AND ALLIED BODIES. flavor of the pine-apple ; oenanthylate of ethyl (C2H5C7Hj302) re- calls green-gage; pelargonate of ethyl (^211509117702) quince; sube- rate of ethyl (Et2C8Hi204) mulberry ; sebacate of ethyl (Et2C7oHig04) melon. Hydride of salicyl (C7H5O2H), or salicylous acid, is the essential oil of meadow-sweet {Spiroea ulmaria), and maybe prepared artificially by the oxidation of salicin [vide p. 370 ). Salicylate of methyl (CH3C7H5O3), or gaultheric acid [Oleum gaultherice, U. S. P.), is the essential oil of winter-green [Gaultheria procumhens)^ and may also be prepared artificially from salicin. By mixing these ethereal salts with each other and with essential oils in various pro- portions, the odor and flavor of nearly every fruit may be fairly imitated. Nitrite of Amyl (C5H77N02). — For the preparation of this sub- stance Maisch recommends a modification of Balard’s process. Amy- lic alcohol is first rectified until pure ; that is until its boiling-point is about 270 ^ F. This alcohol, with about an equal bulk of nitric acid, is introduced into a capacious glass retort, and a moderate heat is ap- plied and very gradually increased. As soon as the mixture ap- proaches boiling, the fire is removed, and the reaction allowed to continue. If the application of the heat has been too rapid or too long continued, considerable frothing occurs, and the contents of the retort are apt to foam over. With a moderate and slowly increased heat, the reaction is less violent and the temperature rises gradually after the removal of the fire and the beginning of boiling. As soon as the thermometer, inserted in the tubulus, rises above 212 ^ F., the i receiver is changed, the distillate now becoming more and more mixed i wfith ethyl-amylic ether and nitrate of amyl, readily perceived by the j change in odor. The distillate obtained below 212^ F. is agitated with an aqueous solution of caustic or carbonate of potassium to remove free acids, and, after separation, the oily liquid is introduced into a clean retort and again slowly heated. The first portion coming over contains amylic aldehyd. When the very slowly increased heat has risen to 205 ^ F., the receiver is again changed and the distillate now collected as nitrite of amyl, until the thermometer reaches 212 ^ F., when the distillation is stopped. I QUESTIONS AND EXERCISES. j 780 . Name the source of methylic alcohol. 781 . What is “methylated spirit?” j 782 . Describe the method by which methylated spirit is detected 1 in a tincture. 783 . In what relation does formic acid stand to methylic alcohol? i 784 . How would you proceed to ascertain whether or not a speci- ; men of sweet spirit of nitre had been made from methylated spirit ? ' 785 . Give details of the production of chloroform from alcohol, i tracing the various steps by equations. PHENYL, CARBOLIC ACID, ETC. 391 786. Is chloroform an ethylic compound ? What is its probable constitution ? 787. How is chloroform purified ? 788. State the character of pure chloroform. 789. Describe the reactions that occur in the manufacture of chloral and chloral hydrate. 790. What is the nature of the action of alkalies on chloral hydrate ? 791. Mention the characters of pure and impure chloral hydrate. 792. Whence is amylic alcohol obtained ? 793. Has valerianic acid any chemical relation to amylic alcohol ? 794. Mention the systematic names of several artificial fruit- essences. 795. What is the formula of nitrite of amyl, and how is it pre- pared ? SALTS AND DERIVATIVES OF RADICALS OF OTHER SERIES THAN THE What has been stated regarding radicals having the general for- mula C^H 2 «-j-i and their salts, may be applied to the radicals of other series. The series C^H 2„_7 includes 'phenyl (CgH.), the hydride of which (CgHgH, or PhH) is common benzol (B. P.), a colorless volatile liquid obtained from coal-tar. Toluol (C^Hg), or methyl-benzol, is one of the products of the distillation of balsam of Peru. The next homologue, xylol (CgH^g), or dimethyl-benzol, is contained in crude wood-spirit and in coal-naphtha : it is a colorless fiuid, having an odor faintly resembling that of benzol ; boiling-point 282^ F. ; sp. gr. .866. Benzol is a powerful solvent of grease, and under the name of Benzine Collas was introduced by M. Collas, in 1848, for cleansing stuffs. By the action of strong nitric acid, benzol yields nitrohenzol (CgH 5 (N 02 )), a liquid termed, from its odor, artificial oil of hitter almonds, or essence of mirhane. Its specific gravity is 1.20 to 1.29. The odor of this essence, however, is not exactly that of essential oil of almonds, and its composition is very different ; so that it is not truly an artificial volatile oil. The natural oil has a sp. gr. of 1.04 to 1.07, and is a hydride of the negative radical ben- zoyl (C^HgOH), a radical derived from the next higher homologue of phenyl by displacement of hydrogen by oxygen. Nitrobenzol yields aniline [vide infra), oil of bitter almonds does not (page 366). The hydrate of phenyl (CgH^HO), or phenic alcohol, or phenol, is the phenic acid or carbolic acid of commerce (Acidum Carbolicum, U. S. P.), a colorless crystalline substance, obtained from coal-tar oil by fractional distillation and subsequent purification. At tempera- tures above 95^ F. it is not an oily liquid. It is only slightly soluble in water. Aqua Acidi Carbolici, U. S. P., but readily dissolved by alcohol, ether, and glycerine [Glyceritum Acidi Carbolici, U. S. E^.). In odor, taste, and solubility (and in appearance when lique- fied by heat or by the addition of 5 per cent, of water) it resembles 392 ALCOHOL AND ALLIED BODIES. creasote, a wood-tar product for which carbolic acid is often substi- tuted. Beside hydrate of phenyl (CgHgHO) coal-tar oil contains cresol, hydrate of cresyl, or cresylic acid (C^H^HO); while wood-tar oil furnishes guaiacol (C7Hg02) — also a product of the destructive distillation of guaiacum-resin — and crtasol (CgHjQ02), or creasote. Certain coloring-matters may be obtained by the oxidation of car- bolic acid ; ammonia mixed with it, and then a small quantity of solution of a hypochlorite gives a blue liquid ; a similar effect is pro- duced on dipping a chip of deal into carbolic acid (or into creasote), then into hydrochloric acid, and afterwards exposing it to the air. By the following tests carbolic acid may be distinguished from crea- sote. The former boils only at 370 '^, while the latter readily dries up at 212 ^. Carbolic acid does not affect a ray of polarized light; creasote twists it to the right. Carbolic acid is either solid or may be solidified by cooling ; creasote is not solidified by the cold produced by a mixture of hydrochloric acid and sulphate of sodium. Creasote from coal (impure or crude carbolic acid) gives a jelly when shaken with collodion ; creasote from viooiL {Creasotum, B. P. and U. S. P.) is unaffected by collodion (Rust). Coal-creasote is soluble in solution of potash, w^ooicreasote insoluble. The coal product is soluble in a large volume of water, and a neutral solution of ferric chloride strikes a blue color with the liquid; wood-creasote is less soluble {Aq2ia Creasotz, U. S. P., is said to contain 1 in 129 ) and not altered by ferric chloride. An alcoholic solution of the coal-oil is colored brown by ferric chloride, a similar solution of true creasote green. Accord- ing to Mr. Thomas Morson pure creasote is unaffected when mixed with an equal volume of commercial glycerine (it is soluble in pure anhydrous glycerine — Fluckiger), while carbolic acid is miscible in all proportions, and will carry into solution even a considerable quantity of creasote. Carbolic acid is a pow^erful antiseptic (avrif anti, against, and sepo, to putrefy). In large doses it is poison- ous, the best antidote being olive oil and castor oil, freely adminis- tered. Acidum Carholicum Impurum, U. S. P., is the impure carbolic acid obtained from coal-tar oil by treating it first wfith an alkali, and then wfith an acid, and finally distilling. It is of a browm shade, and if at first colorless it becomes reddish-brown on exposure. It consists of carbolic and cresylic acids in variable proportion together with impurities derived from coal-tar. 100 measures of w^arm water on being agitated with one measure of the liquid will dissolve out the two acids and should not leave more than 30 per cent, by measure of impurity. Carbolic acid is soluble in oil of vitriol, sulpho-carbolic acid (IICgH5S04) or sulphophenic acid being formed. On diluting and mixing with oxides, hydrates, or carbonates, sulpliocarholates are formed. The formula of sulpho- carholate of sodium is NaC6H5S04; sulphocarholate of zincZw (C(jH 5S04)2H20. Trinitro-carbolic acid (C6ll3(N02)30) is formed on slowly dropping carbolic acid into fuming nitric acid ; it is the yellow dye known as carhazotic acid or picric acid ; most of the picrates are explosive by percussion. Both carbolic acid and benzol are secondary products, obtained in the manufacture of coal-gas ; hence, indeed, the w^ord phenic, and thence phenyl (from phainb, I light, in allusion to the use of coal-gas). Aniline, or AL0IN8. 393 plienylamine, is a product of the action of nascent hydrogen on nitrobenzol. Nitrobenzol. Hydrogen. the substance whence, by oxidation, &c., aniline-red (magenta), -orange, -yellow, -green, -blue, -violet (mauve), and -black are pro- duced. Aloins. — The aloes of pharmacy {Aloe Barbadensts, B. P., and Aloe Socotrma, B. P.) is an evaporated juice, doubtless much altered by the temperature to which it is subjected. Barhaloin, C;^4H3g0j4H20. — This substance, first obtained by T. and H. Smith, occurs in minute crystals in Barbadoes and Soco- trine aloes. It is readily procured from the former by dissolving in boiling water acidified with a little hydrochloric acid, after some hours, pouring off the precipitated resin and evaporating the liquid to a syrup. The aloin* crystallizes out in a day or two. Barbaloin yields by the action of bromine and chlorine substitu- tion compounds, C34H3gBigOi^ and Cg^HggClgOi^GH^O. Nitric acid dropped upon it produces a red color, which soon fades. Boiled for some time with strong nitric acid barbaloin gives, together with oxalic and picric acids, a yellow substance, chrysammic acid, Ci 4H4(N02)404, which furnishes beautiful red salts. Nataloin, C)25H280ii. — This body was discovered by Pluckiger in Natal aloes. It crystallizes readily in rectangular plates, either from spirit or from water. No bromine or chlorine substitution derivatives have yet been formed, but an acetyl compound O. 2511.2.2(021130 ) 60 ii (Tilden) has been analyzed. The existence of this compound serves to corroborate the formula given above. Nataloin moistened with nitric acid gives a red coloration which does not fade. When boiled with nitric acid it yields no chrysammic, but only oxalic and picric acids. The reactions of these two bodies seem to indicate that they are complex phenols. Phenol being the phenyl hydrate, CgH5,IIO, and cresol being the methyl-phenol, CgH^,CH3,HO, the aloins may possi- bly have a similar constitution, that is, they may be the hydrates of radicals in which part of the hydrogen is replaced by groups of atoms. Anthracen, has been obtained by deoxidation of barbaloin. In the series we have the univalent radical allyl (C3H5), whose sulphide ((03115)28) is essential oil of garlic {Allium, U. S. P. ) and sulphocyanate (C3ll5Cy8) the essential oil of mustard. Mustard {sinapis, B. P. and U. 8. P.) is a powdered mixture of black and white mustard-seeds. The white mustard-seed contains sinalbin (C3oH^4N2820ig), a glucoside which, in contact with the aqueous extract of mustard, yields some acrid oil. The black con- tains a ferment resembling the emulsin of almonds (p. 366 ) and my- ronate of potassium. The latter is the body which, under the influ- ence of the former, yields the chief part of the oil. 394 ALCOHOL AND ALLIED BODIES. K,C,oH33NAO,9 x= 2(KHS03) + 2C3H,CNS + 2C«H,,0, + H,0 Myronate of Acid sulphate Oil of Glucose. Water. potassium. of potassium. Mustard. Allyl compounds are also met with in several other cruciferous and liliaceous plants. In the series occurs ethylene or olefiant gas (C 2 H^), the chief illuminating constituent of coal-gas (readily made on heating alcohol with twice its volume of strong sulphuric acid), a bivalent radical, the alcohol of which is glycol (O 2 H 42 HO). Etlierol, or Ethereal Oil [Oleum Ethereum, U. S. P.), or light oil of wine ( CJ 3 H 32 ?), a hydrocarbon polymeric with olefiant gas, is one of the products of the action of excess of sulphuric acid on alcohol : its sp. gr. is 0.917. In the the trivalent hypothetical radical glyceryl (C 3 II 5 ) is found, the hydrate of which (OgH^SHO) is glycerine. The homologues of glycol are termed glycols, the homologues of glycerine glycerines. It will be noticed that the chemical composi- tion of the radicals glyceryl and allyl is identical (C 3 H 5 ), but the former is trivalent and the latte;' univalent ; hence they probably differ in physical constitution ; they are isomeric, possibly polymeric, with each other. From a glyceryl compound (glycerine), however, an allyl salt (iodide) can be produced. By distilling a mixture of glycerine and diniodide of phosphorus, iodide of allyl (C 3 H 5 I) is ob- tained, and on digesting this with sulphocyauate of potassium, the sulphocyanate of allyl, or artificial oil of mustard, results ; identical with the natural oil. Glycerine. Glycerine, or Glyceric Alcohol (O 3 II. 3 HO). — Glycerine is the hydrate 'of glyceryl, glycyl, or propenyl — the basylous radical of most oils and fats. These latter are mainly oleates, palmitates, and stearates of glyceryl ; and when heated with metallic hydrates (even with water — hydrate of hydrogen, HHO — at a temp, of 500^ or 600^ F.) yield oleate, palmitate or stearate of the metal, and hydrate of glyceryl or glycerine. Hence glycerine is a by-product in the manufacture of soap, hard candles, and lead-plaster [vide Index). Properties. — Glycerine is viscid when pure, specific gravity 1.28 (not below 1.25, B. P.) has a sweet taste, is soluble in water or alcohol in all proportions. It has remarable powers as a solvent, is a valuable antiseptic even when diluted with 10 parts of water, and useful as an emollient. In vacuo it may be distilled unchanged but under ordinary atmospheric pressure is decomposed by heat. Test — Heat one or two drops of glycerine in a test-tube, alone or with strong sulphuric acid, acid sulphate of potas- sium, or other salt powerfully absorbent in water; vapors of acrolein (from acer^ sharp, and oleum., oil) are evolved, recognized by their powerfully irritating effects on the eyes and respiratoiy passages. If the glycerine be in solution in water, it must be evaporated as low as possible before applying this test. Besides glycerine itself {Glycerinum^ a ALBUMENOID SUBSTANCES. 395 B. P., Glycerina^ U. S. P.), there are several official prepa- rations of glycerine — solutions of carbolic, gallic, and tan- nic acids and borax in glycerine, and a sort of mucilage of starch in glycerine (Glyceritum Acidi Carbolici^ Gly~ ceritum Acidi Gallici^ Glyceritum Acidi Tannici^ Glyceri- tum Fids Liquidse^ and Glyceritum Sodii Boratis), QUESTIONS AND EXERCISES. <796. Give the names and formulae of compounds of radicals having the general formula C„H 2 n-/", and — e. g., benzol, essential oil of mustard, glycerine, and glycol. 797. State the difference in composition of natural and artificial oil of bitter almonds. 798. How is the so-called artificial oil of bitter almonds prepared? 799. What are the uses, composition, source, and properties of Carbolic Acid ? 800. State the characters by which carbolic acid is distinguished from Creasote. 801. In what relation does carbolic acid stand to cresylic acid ? 802. What is the general formula of sulphocarbolates ? 803. Draw out an equation explanatory of the production of aniline. 804. Mention the chief properties of Glycerine. 805. What is the specific gravity of glycerine ? 806. By what test is glycerine recognized ? 807. Enumerate some official preparations in which glycerine is employed as a solvent. ALBUMENOID SUBSTANCES. Albumen, — Agitate thoroughly, white of egg {Albumen Ovi^ B. P.) with water, and strain or pour off the liquid from the flocculent membranous insoluble matter. One white to 4 ozs. of water forms the ‘‘ Solution of Albumen,” B. P. Test, — Heat a portion of this solution of albumen to the boiling-point ; the albumen becomes insoluble, separating in clots or coagula of characteristic appearance. Other Reactions, — Add to small quantities of aqueous solution of albumen solutions of corrosive sublimate, nitrate of silver, sulphate of copper, acetate of lead, alum, perchloride of tin; the various salts* not only coagulate but form insoluble compounds with albumen. Hence the 396 ALBUxMENOlD SUBSTANCES. value of an egg as a temporary antidote in cases of poi- soning by many metallic salts, its administration retarding the absorption of the poison until the stomach-pump or other measures can be applied. Sulphuric, nitric, and hydrochloric acids precipitate albumen ; the coagulum is slowly redissolved by aid of heat, a brown, yellow, or pur- plish-red color being produced. Neither acetic, tartaric, nor organic acids, generall}^, except gallo-tannic, coagulate albumen. Alkalies prevent the precipitation of albumen. Y^olk or FeZA; of Egg {Ovi Vitellus, B. P.) contains only 3 per cent, of albumen — the white 12^. The yolk also contains only 30 per cent, of yellow fat and 14 of casein. The whole egg ( Ovum, U. S. P.) is also official. Albumen is met wnth in large quantities in the serum of blood, in smaller quantity in chyle and lymph, and in the brain, kidneys, liver, muscles, and pancreas. It is not a normal constituent of saliva, gastric juice, bile, or mucus, but occurs in those secretions during inflammation. It is found in the urine and feces only under certain diseased states of the system. The cause of the coagulation of albumen by heat has not yet been discovered. Albumen has never been obtained sufficiently pure to admit of its composition being expressed by a trustworthy formula ; Gerhardt regarded it as a sodium compound (HNaC 72 HiioNigS 022 ,H 20 }. Fibrin, Casein, Legumin. Fibrin is the chief constituent of the muscular tissue of animals. It occurs in solution in the blood ; and its spontaneous solidification or coagulation is the cause of the clotting of blood shortly after being drawn from the body — a phenomenon which cannot at present be explained satisfactorily. Fibrin may be obtained by whip])ing fresh blood with a bundle of twigs, separating the adherent fibres, and washing in water till colorless. ^ s Average Composition of Blood (in 1000 parts). (Compiled by Kirkes.) Water Albumen Fibrin Bed Corpuscles : Globulin Haematin ' Cholesterin '^O.OS ' Cerebrin 0.40 Serolin 0.02 Oleic and margaric acids Volatile and odorous fatty acid . . . Fat containing Phosphorus 784 70 2.2 123.5 7.5 1.3 CASEIN. 39t Chloride of sodium Chloride of potassium g ^ Phosphate of sodium (Na.^POJ Carbonate of sodium Sulphate of sodium Phosphates of calcium and magnesium . . . Oxide and phosphate of iron Extractive matters, biliary-coloring-matter, gases, and accidental substances . , 3.6 .36 .2 .84 .28 .25 .50 5.47 1000. Percentage proportion of the chief constituents of Blood. Water 78.4 Red corpuscles 13.1 Albumen of serum 7.0 Inorganic salts .603 Extractive, fatty, and other matters . . . .677 Fibrin 22 100 . Casein occurs in Cow’s Milk (Lac, B. P.) to the extent of 3 per cent., dissolved by a trace of alkaline salt. Its solution does not spontaneously coagulate like that of fibrin, nor by heat like albumen ; but acids cause its precipitation from milk in the form of a curd (cheese) containing the fat (butter)-globules previously suspended in the milk, a clear yellow liquid (or whey) remaining. Curds and whey are also produced on adding to milk a piece, or an infusion, of rennet, the salted and dried inner membrane of the fourth stomach of the calf. The exact action of rennet is not known. Average composition of 1000 parts of Millc. Solid Casein Specific gravity. W ater. consti- tuents. and ex- tractive. Sugar. Butter. Salts. Woman . . . 1.033 889 Ill 40 44 27 2 Cow 1.034 864 136 55 38 36 7 Specific gravity alone, as taken by the form of hydrometer termed a lactometer, or even by more delicate means, is of little value as an indication of the richness of milk, the butter and the other solids exerting an influence in opposite directions. Good cow’s milk affords from 11 to 13 per cent, by volume of cream, and 3 to 3^ per cent, of butter. The water of milk seldom or never varies more than from 86^ to 87|^ per cent., and the solid constituents from 13^ to 124. Town milk is commonly 3 and sometimes 2 parts milk and 1 part water. Under the microscope milk is seen to consist of minute cor- 34 398 ALBUMENOID SUBSTANCES. puscles floating in a transparent medium. These corpuscles consist of fatty matter (butter) contained in a filmy albumenoid envelope. Legumin or vegetable casein is found in most leguminous seeds, such as sweet and bitter almonds. Peas contain about 25 per cent, of legumin. Vegetable albumen is contained in many plant-juices, and is depo- sited in flocculi on heating such liquids. Vegetable fibrin is the name given by Liebig and Dumas to that portion of the gluten of wheat which is insoluble in alcohol and ether [vide p. 356). Albumenoid substances are nearly identical in percentage compo- sition. Albumen (and fibrin) contains 53.5 of carbon, 7 of hydrogen, 15.5 of nitrogen, 22 of oxygen, 1.6 of sulphur, and .4 of phosphorus. Casein contains no phosphorus. These three bodies are often termed the plastic elements of nutrition, under the assumption that animals directly assimilate them in forming muscles, nerves, and other tissues, — starch, sugar, and similar matter forming the resp^Va^ort/ materials of food, because more immediately concerned in keeping up the temperature of the body by the combustion going on between them, and their products, and the oxygen of the air in the blood. Musk (i^osc/l^fc5, B. P. and U. S. P.), “the inspissated and dried secretion from the preputial follicles of Mosclius moschiferus'' (the Musk-Deer), is a mixture of albumenoid, fatty, and other animal matters with a volatile odorous substance of unknown composition. GELATIGENOUS SUBSTANCES. This group of nitrogenous bodies differs from true albumenoid in containing less carbon and sulphur and more nitrogen. They are contained in certain animal tissues, and on boiling with water yield a solution which has the remarkable property of solidifying to a jelly on cooling. The tendons, ligaments, bones, skin, and serous membranes afford gelatine proper ; the cartilages give chondrine, which differs from gelatine in composition and in being precipitated by vegetable acids, alum, and the acetates of lead. The purest variety of gelatine isinglass, B. P. (Icthyocolla, U. S. P.), “the swimming-bladder or sound of various species of Acipenser, Linn., prepared and cut in fine shreds.’^ h>mall quantities are more easily disintegrated by a file than a knife. Fifty grains dissolved in 5 ounces of distilled water forms the official “ Solution of Gelatine,” B. P. i Glue is an impure variety of gelatine, made from the trimmings of hides ; size is glue of inferior tenacity, prepared from the parings of , parchment and thin skins. “ Among the varieties of gelatine derived ^ from different tissues and from the same sources at different ages, i much diversity exists as to the firmness and other characters of the , solid formed on the cooling of the solutions. The differences between ' isinglass, size, and glue, in these respects, are familiarly known, and . afford good examples of the varieties called weak and strong, or low : and high, gelatines. The differences are sometimes ascribed to the i quantities of water combined in eu.ch case with the j)ure or anhy- i PEPSINE. 399 drous gelatine, part of which water seems to be chemically combined with the gelatine ; for no artificial addition of water to glue would give it the character of size, nor would any abstraction of water from isinglass or size convert it into the hard dry substance of glue. But such a change is effected in the gradual process of nutrition of the tissues ; for, as a general rule, the tissues of an old animal yield a much firmer or stronger jelly than the corresponding parts of a young animal of the same species.” (Kirke’s Physiology.) Gelatine ap- pears to unite chemically with a portion of the water in which it is ^soaked when used for culinary and manufacturing purposes, for a solution of glue in hot anhydrous glycerine does not yield an ordinary jelly on cooling. PEPSINE. Pepsine (from pe'ptd, to digest) is a nitrogenous substance existing in the gastric juice, and as a viscid matter in the peptic glands and on the walls of the stomachs of animals. The mucous membrane of the stomach (of the hog, sheep, or calf, killed fasting) is scraped, and macerated in cold water for twelve hours ; the pep- sine in the strained liquid is then precipitated by acetate of lead, the deposit washed once or twice by decantation, sulphuretted hydro- gen passed through the mixture of the deposit with a little water to remove the whole of the lead, and the filtered liquid evaporated to dryness at a temperature not exceeding 105^ F. Pepsine is a power- fill promoter of digestion ; its solution is hence frequently termed artificial gastric juice. As met with in pharmacy its strength varies greatly. It is often prepared by simply mixing with starch the thick liquid obtained on macerating the scraped stomach with w^ater, and evaporating to dryness. ( Vide Pharmaceutical Journal. 1865-66, p. 112, and 1871-72, pp. 785 and 843.) QUESTIONS AND EXERCISES. 808. In what form is albumen familiar ? 809. Name the chief test for albumen. 810. Why is the administration of albumen useful in cases of poisoning ? 811. Mention the points of difference between yolk and white of egg. 812. From what sources other than egg may albumen be obtained? 813. In what respects does fibrin differ from albumen ? 814. Enumerate the chief constituents of blood. 815. How may fibrin be obtained from blood ? 816. State the difference between casein, fibrin, and albumen. 817. AVhat are the relations of cream, butter, curds and whey, and cheese, to milk ? 400 PATTY BODIES. 818 . Describe the microscopic appearances of blood and of milk. 819 IIow much cream should be obtained from good milk ? 820 . What is the percentage of .water in genuine milk ? 821 . Name sources of vegetable casein and vegetable albumen. 822 . Give the percentage of nitrogen in albumenoid substances. 823 . Describe the chemical nature of musk. 824 . In what lie the peculiarities of gelatine ? 825 . To what extent do isinglass, glue, and size differ ? 826 . Whence is pepsine obtained ? 827 . How is pepsine prepared ? FATTY BODIES. SOAPS, SOLID FATS, FIXED OILS, VOLATILE OILS, CAMPHORS. General relations . — Oils and fats are, apparently, almost as sim- ple in constitution as ordinary inorganic salts. Just as acetate of potassium (KC2H3O2) is regarded as a compound of potassium (K) with the characteristic elements of all acetates (C2H3O2), so soft soap is considered to be a compound of potassium (K) with the ele- ments characteristic of all oleates (CigH3302), and hence is chemically termed oleate of potassium (KC18H33O2). Olive oil, from which soap is commonly prepared, is mainly oleate of the trivalent radical gly- ceryl (C3H5), the formula of pure fluid oil being C3H.3G18H33O2, and its name oleine. The formation of a soap, therefore, on bringing together oil and a moist oxide or hydrate, is a simple case of double decomposition, as seen already in connection with lead plaster (p. 188 ), or in the following equation relating to the formation of common hard soap : — i SNaHO 4 - C3H,3C,8H3302 = 3NaC,8H3302 + C3H53HO I Hydrate of sodium Oieate of glyceryl Oleate of sodium Hydrate of glyceryl i (caustic soda) (vegetable oil). (hard soap). (glycerine). Berthelot has succeeded in preparing oil artificially from oleic acid and glycerine ; and it is said to be identical with the pure oleine of , olive and of other fixed oils. Hard fats chiefly consist of stearine — thiit | is, of tristearate of glyceryl (C3H53C]8H3302). Mr. Wilson, of Price’s | Candle Company, obtains stearic and oleic acids and glycerine by j simply passing steam, heated to 500 ^ or 600 ^ F., through melted fat. ' Both the glycerine and fat acids distil over in the current of steam, i the glycerine dissolving in the condensed water, the fat-acids floating 1 on the aqueous liquid. The author finds that oleic acid readily combines with alka- loids and most of the metallic oxides or hydrates, forming oleates » which are soluble in fats. In this way active medicines may be ! administered internally in conjunction with oils, or externally in , the form of ointments. Soaps. — Olive oil boiled with solution of potash yields potassium soap, or soft soap {Sapo Mollis^ B. P.) ; with! soda, sodium soap, or hard soap {Sapo Durns^ B. P. and U. ^ SOAPS 401 S. P.) ; mixed with ammonia, an ammonium soap {Lini- mentum Ammoniae^ B. P. and U. S. P.) ; and with lime- water, calcium soap {Linimentum Calcis^ B. P. and — flax- seed oil — U. S. P.), — all oleates, chiefly of the respective basylous radicals. Their mode of formation is indicated in the foregoing equation. The alkali soaps are soluble in alcohol, the others insoluble. The official characters of Hard Soap are : “ grayish-white, dry, inodorous ; horny and pulverizable when kept in dry warm air ; easily moulded when heated ; soluble in rectified spirit ; not imparting an oily stain to paper ; incinerated it jdelds an ash which does not deliquesce.’^ And of Soft Soap: “yellowish-green, inodorous, of a gelatinous consistence ; soluble in rectified spirit; not imparting an oily stain to paper: incinerated it yields an ash which is very deliquescent.” The hard soap met with in trade is made from all varieties of oil, the commoner kinds being simply the product of the evapo- rated mixture of oil and alkali ; while the better sorts have been separated from alkaline impurities and the glycerine by the addi- tion of common salt to the liquors, which causes the precipitation of the pure soap as a curd. Potash soap is not precipitable by salt. Bile, the gall of the ox [Bos taurus, Linn.), freed from mucus by agitating with twice its bulk of rectified spirit (in vrhich mucus is insoluble), filtering, and evaporating, yields the official Purified Ox- Bile [Fel Bovinum Purificatum, B. P.) : the latter has a resinous appearance, but is chiefiy composed of two crystalline substances having the constitution of a soap ; the one is glycocliolate, or simply cliolate, of sodium (Na026H4.^N0g), the other is termed tauro- cholate of sodium (NaC26H^4N07S). Both taurocholates and gly- cocholates are conjugated bodies readily yielding, the former cho- lalic acid (H2C14H39O5) and taurine (C2H7NO3S), the latter cholalic acid and glycocine or glycocoll (O2H.NO2), a body having interest- ing physiological relations, inasmuch as it is obtainable from gelatine (hence the name glycocoll, from y%vxv^, glucus, sweet, and holla, glue) and hippuric acid. The presence of bile in a liquid such as urine, is detected by Pettenkofer’s test. The fluid is gradually mixed with half its bulk of strong sulphuric acid in a test-tube, rise of temperature being prevented by partial immersion of the tube in water. A small quantity of powdered white sugar is then introduced and well mixed with the acid liquid, and more sulphuric acid then poured in ; as the temperature rises a reddish or violet coloration is produced. The cholalic acid liberated in the reaction furnishes the color. Solid Fats. — 1. Lard [Adejys Prceparatus, B. P. and U. S. P.) is the purified internal fat of the abdomen of the hog — the perfectly fresh omentum or flare, washed, melted, strained, and dried. 2. Benzoated Lard [Adeps Benzoatus, B. P.) is prepared lard heated over a water-bath with benzoin (10 grains per ounce), which commu- nicates an agreeable odor and prevents or retards rancidity. Purified 402 FATTY BODIES. lard is a mixture of oleine and stearine ; margarine, the margarate of glyceryl, was formerly supposed to be a constituent of lard and other soft fats, but is now regarded as a mere mixture of palmitine (the chief fat of palm oil) and stearine. 3. Yellow Wax ( Cera Flava, B. P. and U. S. P.), the prepared honeycomb of the Hive-Bee, and the same bleached by exposure to sunlight. 4. White Wax ( Cera Alba, B. P. and U. S. P.), according to Brodie, is chiefly a mixture of Cerotic Acid (HO27H53O.J, Palmitate of Melissyl (C3oH6i^]6H3i02), and about 5 per cent, of Ceroleine, the body to which the color, odor, and tenacity of wax are due. 5. Spermaceti ( Cetacenm, B. P. and U. S. P.) is W^palmitate of cetyl (Ci6H330^gH3^02), or cetine; when sapo- nified it yields not glycerine, the hydrate of glyceryl (CgH^SHO), but etlial, the hydrate of cetyl (CigH33EIO) ; it is the solid crystalline fat accompanying sperm oil in the head of the spermaceti-whale. 6. Suet, the internal fat of the abdomen of the sheep, purified by melting and straining, forms the official Prepared Suet (Sevum Prceparatum, B. P. and XJ. S. P.) ; it is almost exclusively composed of stearin (C3H53Cj8H3g02). 7. Expressed oil of nutmeg [Oleum Myristicce Expressum, B. P.) is a mixture of a little volatile oil with much yel- low and white fat, the latter a myristate of glyceryl (C3H53C14H27O2). 8. Oil of tlieobroma, or Cacao-butter ( Oleum Theobromce, B. P. and U. S. P.), is a solid product of the ground seeds or cocoa nibs of the Tlieobroma cacao, which also furnish cocoa and chocolate. 9. Cocoa- nut oil, a soft fat largely contained in the edible portion of the nut of Cocos nucifera, or common cocoa-nut of the shops, a body con- taining glyceryl united with no less than six different univalent acid- ulous radicals, namely, the caproic (C6Hji02), caprylic (C8H15O2), rutic (C16H19O2), lauric (C12H23O2), myristic (O14H27O2), and palmitic (CigH3i02) — radicals which, like some from common resin, when united with sodium, form a soap differing from ordinary hard soap (oleate of sodium) by being tolerably soluble in a solution of chloride of . sodium ; hence the use of cocoa-nut oil and resin in making marine soap, a soap which, for the reason just indicated, readily yields a lather in sea-water. I Fixed Oils. — Fixed and Volatile oils are naturally distinguished ^ by their behavior when heated ; they also differ in chemical constitu- tion, a fixed oil being, apparently, a combination of a basylous with an acidulous radical, while a volatile oil is commonly a neutral hy- drocarbon. Drying and Non-drying Oils. — Among fixed oils, most of which are oleate with a little palmitate and stearate of glyceryl, a few, such as, 1, linseed [Oleum Lini, B. P. and U. S. P., contained in Lini Semina, B. P., Linum, U. S. P., or Flaxseed, the ground residue of 1 which, after removal of some of the oil, is linseed meal, Lini Farina, \ U. S. P.), and, 2, cod-liver [Oleum Morrhuce, B. P. and U. S. P.), j and, to some extent, castor and croton, are known as drying oils, j from the readiness with which they absorb oxygen and become hard- i ened to a resin. Linseed commonly contains 37 or 38 per cent, of j oil ; 25 to 27 per cent, is obtained by submitting the ground seeds to I hydraulic pressure, 10 or 12 per cent, remaining in the residue oil- i cake. Among the non-drying oils arc the following: 3, Almovd ; FIXED OILS. 403 oil, indifferently yielded by the bitter [Amygdala Amara, B. P. and U. S. P.) or sweet seed [Amygdala Dulcis, B. P. and U. S. P.) ; 4 , Croton oil [Oleum Crotonis, B. P., Oleum Tiglii, U. S. P.), which seems to contain crotonate of glyceryl (C3H5304H502)- Geuther, however, states that no such acid as crotonic is obtainable from croton oil, but acetic, butyric, valerianic, and higher members of the oleic series, together with tiglic acid, 5 , Olive oil ( Oleum Olivoe, B. P. and U. S. P.), already noticed ; 6, Castor oil [Oleum Ricini, B. P. and U. S. P.), a ricinoleate of glyceryl (C3H53C18H33O3) or ricinoleine, a slightly oxidized oleine, soluble, unlike most fixed oils, in alcohol; 7 , Oil oi male fern [Filix Mas, B. P. and U. S. P.) , a vermifuge obtained by exhausting the rhizome with ether and removing the ether by evaporation — a dark-colored oil containing a little volatile oil and resin, and officially termed an ex- tract [Extractum Filicis Liquidum, B. P.) ; 8, Fixed oil of mustard, a bland, inodorous, yellow or amber oil, yielding, by saponification and action of sulphuric acid, glycerine, oleic acid, and erucic acid, HO22H41O2 (Darby) ; 9 , Lycopodium Oil from the sporules of Club- moss. Their physical qualities and the formulae of their acidulous radicals show that the fatty bodies are closely related, and indicate that the natural processes by which they are formed are probably as closely related. The following Table, from Miller’s “ Elements of Chemis- try,” well shows the homology of the fat-acids, and gives their names, formulae, melting-points, boiling-points, and natural and artificial sources. For further information respecting the more commonly occurring of these acids, the reader is referred to the Index, and for others to larger chemical works, or Watts’s “Dictionary of Chemistry.” Acids. Formulae. Melting point. Boiling point. Whence obtained. Molec. Vol. = 2. op. ^C. °F. °G. f Red ants; distillati Formic HC H O 2 21 —6 221 105.3 J oxalic acid ; and ( [ tion of amylaceou f other organic bodi( ( Distillation of wood; Acetic HC, H 3 O, 63 17 243 117 -J oxidation of alco- ( hoi, etc. Propionic .... HCsH^O, ... ... 284 140 ( Fermentation of gly- \ cerin, etc. r Butter ; fermenta- Butyric HC 4 H, 0, below —20 314 157 -j tion of lactic acid, 0 I etc. r Valerian-root ; oxi- Valerianic... HCj H, 0 , (( u 347 175 \ dation of fousel f oil. Batter. Caproic HCe H„0, 392 200 (Enanthylic. HC, H 13 O, u a 298? 148? f Castor oil by distil- 1 lation, etc. Caprylic HC, H,,0, 59 15 457 236 Butter; cocoa-nut oil. Pelargonic... hc,h„o, ... 500 260 i Leaves of the gera- \ nium. Rutic HCioHjg 02 86 30 ... ... ( Batter; oil of rue b \ dation. Laurie HC^HggOg 110 43 ... ... 1 Cocoa-nut oil ; berries ( bay tree. Myristic HCi,H 2,02 129 54 ... (Nutmeg-butter; cocc \ oil, etc. Palmitic HC,eH 3,02 143.6 62 ... ... j Palm oil ; butter ; bee \ etc. Stearic HC 18 H 35 O 2 159 70.5 Most solid animal fat Arachidic.... HC2(|H3y02 167 75 ... Butter; oil of grounc Cerotic HC 2 ,H ,302 174 79 Beeswax. Melissic HCaoH^gO^ 192 89 ... ... Beeswax. QUESTIONS AND EXERCISES. 828. Give a sketch of the general chemistry of fixed oils, fats and soaps. 829. What is the difference between Hard and Soft Soap ? | 830. Which soaps are official ? J 831. Name the source of lard, and state how “ Prepared Lard" is i obtained. « 832. State the composition of Beeswax. | 833. In what does Spermaceti differ from other solid fats ? 834. ISfention the chief constituent of Suet. 835. Whence is Cacao-Butter obtained ? ; 836. Why is marine soap so called, and from what fatty matter * is it exclusively prepared ? ! VOLATILE OILS. 405 837. What do you understand by drying and non-drying oils ? 838. In what respect does Castor Oil differ from other oils? 839. How is oil of male fern {Ex. Fili.cis Liquidum) prepared ? 840. Mention the sources and formulaB of the following fat-acids : formic, acetic, propionic, butyric, valerianic, caproic, oenanthylic, caprylic, pelargonic, and rutic. Volatile Oils. — The Volatile or Essential Oils exist in various parts of plants probably as mere combinations of carbon and hydro- gen ; but such hydrocarbons are prone to change when in contact with oxygen or moisture ; hence these liquids as they occur in phar- macy are usually mixtures of liquid hydrocarbons or elceoptens with oxidized hydrocarbons, ’which are commonly solid or camphor-like bodies termed stearoptens. On cooling a volatile oil, a stearopten (from gtiap, stear, suet) often crystallizes out ; or on distilling an oil, it remains in the retort, being less volatile than an elaeopten (from tXotcov, elaion, oil, and oTtroyav, optornai, to see). Volatile oils should be preserved in well-closed bottles. The process by which volatile oils are usually obtained from herbs, flowers, fruits, or seeds, maybe imitated on the small scale by placing the material (bruised cloves or cara- ways for instance) in a tubulated retort, adapting the retort to a Liebig’s condenser, and passing steam, generated in a Florence flask, through a glass tube to the bottom of the retort. The steam in its passage upward through the sub- stance will carry the oil over the neck of the retort into the condenser, and thence, liquefied and cooled, into the receiv- ing vessel, where the oil will be found floating on the water. It may be collected by running off the distillate through a glass funnel having a stopcock in the neck, or by letting the water from the condenser drop into an old test-tube which has a small hole in the bottom, or any similar tube placed in a larger vessel, the water and oil being subsequently run off separately from the tube as from a pipette. The water will in most cases be the ordinary official medicated water of the material operated on (Aqua Aurantii Floris^ Anethi^ Carui^ Cinnamomi^ Fceniculi^ Mentlise Piperitse.^ Menthse Viridis.^ Pimentse^ Posse — from Posse Gentifolise Petala^ B. P. and U. S. P. — Sambuci). Volatile oils, like fixed oils, stain paper, but the stain of the former is not permanent like that of the latter. Oils of lemon and orange are some- times obtained by mere pressure of the rind of the fruit. A large number of volatile oils are employed in medicine, either in the pure state, in the form of saturated aqueous solution (medicated waters), solution in spirit of wine, 1 in 5 {Essentm Anisi and Essen tia Mentlice Piperitce, B. P.) and 1 in 50 {Spiritus Cajuputi, Juni^ peri, LavandidcCj Menthce Piperitce, Myristicce, Posmarini), or 406 PATTY BODIES. as leading* constituents in various barks, roots, leaves, etc. The strength of Spzritus Amsi, U. S. P. ; Sp. Cznnamomi, U. S. P. ; Sp. Menthce Pzperztce, U. S. P. and SiJ. Menth. Vzrzdzs, [J. S. P., is 1 of oil to 15 of spirit of wine. Perf umes (“ scents” or “ essences,” including “Lavender-Water” and “ Eau de Cologne”) are for the most part solutions of essential oils in spirit of wine, or spirituous infusions of materials containing essential oils. The following oils are, directly or indirectly, official in the British Pharmacopoeia. 1. Volatile oil of Bitter Almond (p. 366). 2. Oil of Dill [Oleum Anethi, B. P.), a pale yellow, pungent, acrid liquid distilled from dill-fruit. It contains a hydrocarbon anethene (OioHj^.) and an oxidized oil (CioH^^O) identical with the carvol of oil of caraway (Gladstone). 3. Oil of Aniseed ( Oleum Anisi, B. P.), a colorless or pale yellow liquid, of sweetish warm flavor, distilled in Europe from the Anise-fruit [Pimpinella anisum), and in China from the fruit of Star-Anis [lllicium anisatum ) ; it is a mixture of a hydrocarbon isomeric with oil of turpentine and a stearopten (CJ0H12O), which crystallizes out at low temperatures. 4. Oil of Chamomile ( Oleum Anthemidis, B. P.), a bluish or, when old, yellow oil, of character- istic odor and taste, distilled from chamomile flowers [Anthemidis flares, B. P.) : the official variety [Anthemis nohilis) yields an oil composed of a hydrocarbon (CioHj^.) and an oxidized portion (CjoHj (,02 or OjHj^O), which, heated with potash, gives angelate of potassium (KC5H-O2), whence is obtained angelic acid (HC5H7O2) ; while the flowers of another variety [Matricaria Chamomilla, U. S. P.) contain a stearopten (CioH^pO) having the composition of laurel- camphor. 5. Oil of Horseradish-root [Armoracice Radix, B. P.) is, according to Hofmann, the sulphocyanate of butyl or tetryl (C^HyCNS); it is the chief ingredient of Spiritus Armoracice Compositus, B. P. 6. Oil of Sweet-Orange Peel [Aurantii Dulcis Cortex, U. S. P.) and Oil of Bitter-Orange rind [Aurantii Amari Cortex, B. P. and U. S. P.), the flavoring constituent of the official syrup of the peel [Syrupus Aurantii, B. P.), and the oils of, 7, lemon [Oleum Limonis, B. P. and U. S. P.), from Lemon Peel [Limonis Coz'tex, U. S. P.) ; 8, lime; 9, bergamot ( Oleum Bergamii, U. S. P.) ; 10, citron and a variety of citron termed cedm, resemble each other in composition, containing hespez'idine, a hydrocarbon and a small quantity of oxidized hydrocarbons OisHjoOg, and (Wright and Piesse) C20H30O3). 11. Oil of Neroli or Orange- Flower^ the aqueous solution of which is official in the forms of water [Aqua Aurantii Floris, B. P. and U. S. P.) and syrup [Syrupus Aurantii Floris, B. P. and U. S. P.), contains a fragrant hydrocarbon (CioHjg), colorless when fresh, but becoming red on exposure to light, and an inodorous oxidized hydrocarbon. 12. Oil of Buchu-leaves [Bucliu Folia, B. P. and U. S. P.) consists of a hydrocarbon holding in solution a crystalline stearopten. 13. Oil of Cardamoms, from the seeds of the capsules ( Cardamomum, B. P. and U. S. P.), is chiefly a hydrocarbon (Cjglljg) isomeric with oil of turpentine. 14. Oil of Cajuput ( Oleum Cajuputi, B. P. and U. S. P.) is a mobile bluish liquid the composition of which (C,oHigO) seems to be that of the common hydrocarbon associated with the elements of water. The green coloring matter of most samples of cajuput oil VOLATILE OILS. 407 is organic. Guibourt, and, more recently, Histed, have found copper in many specimens of cajuput oil. 15. Oil of Cara^vay4vmi ( Carum, U. S. P.) [Oleum Carui, B. P., Oleum Cart, U. S. P.) is a mixture of carvene and carvol (CjoHj^O). 16. Oil of Cloves [Oleum Ca- ry ophylli, B. P. and U. S. P.) and of Pimento [ Oleum Pimentae, B. P. and U. S. P.), both heavier than water, contain a liquid hydrocarbon (O.oH.e), eugenic acid a solid body, eugenin, isomeric with eugenic acid, and a second crystalline substance, caryophyllin (CioHjgO), isomeric with common camphor. 17. Oil of Cascarilla- bark [Cascarillce Cortex, B. P. and U. S. P.) has not been fully ex- amined. 18. Oil of Cinnamon-'hi\,Y\i [ Cinnamomi Cortex, B. P. and U. S. P.) and of Gassm-bark is mostly hydride of cinnamyl (CgH^OH). Boiled with nitric acid it furnishes hydride of benzoyl (C7H5OH) and benzoic acid (HO7H5O2). with chloride of lime yields benzoate of cal- cium(Ca2C7H502), and with caustic potash gives cinnamate of potas- sium (KC9H-O2). The specific gravity of oil of cinnamon ( Oleum Cinnamomi, B. P. and U. S. P.) varies from 1.025 to 1.050. 19. Oil of Citronella is chiefiy composed of citronellol (OjoHigO), proba- bly isomeric with the ahsintliol of wormwood (Gladstone). 20. Oil of Copavia [Oleum Copaibce, B. P. and U. S. P.) and, 21, of Cubebs [Oleum Cubebce, B. P. and U. S. P.) are hydrocarbons having the formula C15H24. 22. Oil of Coriander [ Coriandri fructrus, B. P., Coriandrum, U. S. P., Oleum Coriandri, B. P.) seems to have the composition of hydrous oil of turpentine (CjgH^gH20). 23. Euca- lyptus globulus furnishes an oil the more volatile and chief portion of which is eucalyptol (C12H20O). 24. Oil oi Juniper [Oleum Juni- peri, B. P. and U. S. P.), the active constituent of Juniper Tops and Berries [Jimiperus, U. S. P.), is a hydrocarbon (CigHjg) which by contact with water yields a wdiite crystalline hydrous compound (CioHjgH20). 25. Oil of Eennel-iruit [Oleum Foeniculi, U. S. P.) [Foeniculi Fructus, B. P. and U. S. P.) differs in odor, but contains the same proximate constituents as oil of anise. 26. Oil of Lavender [Oleum Lavandulae, B. P. and U. S. P.) contains a hydrocarbon which by oxidation yields common camphor. 27. Oil or Butter of Orris [Iris Florentina) is a soft camphor (08H^g02), lighter than water. 28. Oil of Peppermint [Oleum Menthae Piperitce, B. P. and U. S. P.) consists of a hydrocarbon, mentliene (OjgHjg), which differs from that of most volatile oils, and hydrous menthene (CioH^8H20), a crystalline stearopten. 29. Oil of Spearmint [Oleum Menthae Viri- dis, B. P. and U. S. P.) contains a liquid expressed by the formula C10H20O ; also, according to Gladstone, menthol (C10H44O) isomeric with carvol. 30. Oil of Nutmeg [ Oleum Myristicae, B. P. and U. S. P.) and of the arillus of the nutmeg or mace [Mads, U. S. P.) is composed of a hydrocarbon myristicene (OjgHig), and myris- ticol (OigHj^O) — Gladstone. 30a. Oil of Origanum [Oleum or igani, U. S. P.) from Origanum vulgare, U. S. P., is of a bright-yellow color, having an odor somewhat like peppermint ; it is a mixture of a liquid hydrocarbon and a camphor which is deposited after long standing. 31. Oil or Otto or Attar of Cabbage-rose petals [Rosae Centifoliae Petals, B. P. and U. S. P., Oleum Rosae, U. S. P.) gives the fragrance to Bose water [Aqua Rosae, B P.). It resembles most 408 FATTY BODIES. other volatile oils in being composed of a hydrocarbon and an oxi- dized portion, but differs from all in this respect, that the hydro- carbon is solid and is destitute of odor, while the oxygenated constituent is liquid and the source of the perfume. According to Fluckiger the solid hydrocarbon (CgH^g) yields succinic acid as the chief product of its oxidation by nitric acid, and in other respects affords evidence of belonging to the paraffin series of fats. 32. Oil of Rosemary-tops [Oleum Rosmarini, B. P. and U. S. P.) is a mixture of hydrocarbon, oxygenized oil, and stearopten in variable proportions. 33. Oil of Rue [Oleum Rutce, B. P. and U. S. P.) contains a small quantity of hydrocarbon (CjgH^g) with some rutic aldehyd (CioH 2 o^)> according to Greville Williams is chiefly euodic aldehyd (O 11 H 22 O), some lauric aldehyd (Ci^Hj^O) also being present. Gorup-Besanez and Grimm have obtained oil of rue (C 11 H 22 O) artificially as one of the products of the destructive dis- tillation of acetate and caprate of calcium. 34. Oil of Savin [Oleum Sdbince^ B. P. and U. S. P.) is isomeric with oil of turpentine CioHig). 35. Oil of Elder-flowers [Sam, bud Flores, B. P. and U. S. P.) occurs in very small quantity ; it has a butyraceous consistence. It contains a hydrocarbon, samhucene (OjgHjg), and probably a cam- phor. 36. Oil of Sassafras-root [Oleum Sassafras, U. S. P.), specific gravity 1.094 [Sassafras Radix, B. P. andU. S. P.), yields safren (CjgHjg) and large quantities of a stearopten, sassafrol (CioHig02). 37. Oil of Mustard [Oleum Sinapis, B. P.) is the sulphocyanate of allyl (p. 393). If adulterated with alcohol, its specific gravity is below 1.015. 38. Oil of Turpentine [Oleum Tere- binthinoe, B. P. and U. S. P.). Turpentine itself is really an oleo- resin of about the consistence of fresh honey. It flows naturally or by incision from the wood of most coniferous trees, larch [Larix, Europcea) yielding Venice Turpentine, Abies balsamea furnishing Canadian Turpentine, Balsam of Fir or Canada Balsam ( Tere- bintliina Canadensis, B. P. and U. S. P.), Pistachia terebinthus, the variety termed Chian Turpentine, and the Pinus palustris, Pinus abies, and Pinus pinaster affording American Turpentine ( Terebinthus, U. S. P.). Pinus maritima gives the French or Bor- deaux Turpentine. By distillation turpentine is separated into rosin or resin (which remains in the still), and essential oil of turpentine, often termed simply turpentine, spirit of turpentine, or ''turps” (which distils over). Mixed with alkali to saturate resinous acids, and redistilled, oil of turpentine furnishes rectified oil of turpentine. Under the influence of heat, chemical agents, or both, oil of turpen- tine (CjgHjg) yields many derivatives of considerable chemical in- terest. 39. Oil of Valerian-root ( Valerianae Radix, B. P. and U. S. P.) [Oleum Valerianae, U. S. P.) is a mixture of a hydrocar- bon (CigHig) and valerol (CgHjgO). Yalerol slowly oxidizes to valerianic acid, known by its smell. A similar change occurs at once if the oil of valerian be allowed to fall, drop by drop, on heated caustic potash: CgHig0-p3KH0-+-Il20 =K 2 C 03 +KC 5 H 902 -h 3 n 2 . i By the action of sulphuric acid on the valerianate of potassium thus I produced, valerianic acid is obtained. 40. Oil of Ginger [Zingiber, | B. P. and U. S. P.) has the composition of hydrous oil of turpentine. | 41. Woi'mseed [Chenopodium, U. S. P.) contains a volatile oil. CAMPHORS. 409 42. Oil of Thyme [Oleum Thymi, U. S. P.) is a mixture of thymene (CjoHjg) and thymol a solid white crystalline body. Thymol is also contained in, 43, Oil of Horsemint [Monarda, U. S. P.). Camphors. — In addition to the stearoptens or camphors already mentioned as being contained in or formed from volatile oils, there is one that is a common article, of trade. It is obtained from the wood of Cam'phora officinarum, or Camphor-Laurel, in Japan (termed in Europe, Dutch camphor, because imported by the Dutch) and in China (known as Formosa camphor), by a rough process of distillation with w'ater, and is resublimed in this country [Cam- phora, B. P. and U. S. P.). The formula of laurel-camphor is CigHjgO. The essential oil [Oleum Camphorce, U. S. P.), from which doubtless camphor is derived by oxidation, is easily obtained from the wood, and is occasionally met with in commerce under the name of liquid camphor or camphor oil; its formula is C 20 II 32 O; by exposure to air it becomes oxidized and deposits common cam- phor, C2oH320“hO = 2CioH^gO. There is another kind of camphor in European markets less common than laurel-camphor, but highly esteemed by the Chinese ; it is obtained from the Dryobalanops aromatica, and denominated Sumatra or Borneo camphor. It differs slightly from laurel-camphor in containing more hydrogen, its for- mula being CigHjgO. It is accompanied in the tree by a volatile oil (CioHjg) isomeric with oil of turpentine. This oil hornehne, is also occasionally met with in trade under the name of liquid camphor or camphor oil, but differs from laurel-camphor oil in not depositing crystals on exposure to air. Camphor is soluble to a slight extent in water (40 grains per gallon, Pooley). The official Camphor- w^ater [Aqua Camphorce, B. P. and U. S. P.), or Camphor mixture, is such a solution. Cantharidin (C 5 llg 02 ?), the active blistering principle of can- tharides [Cantharides, B. P., Cantharis, U. S. P.) and other vesi- cating insects, has most of the properties of a camphor or stearopten. It slowly crystallizes, from an alcoholic tincture of the beetles, in fusible, volatile, micaceous plates. The following process for the extraction of cantharidin is by Fumouze : Powdered cantharides are macerated with chloroform for twenty-four hours; and this treatment is repeated twice with fresh quantities of solvent, the residue having been well squeezed each time. The collected solutions are then distilled, and the dark-green residue treated with bisulphide of car- bon, which dissolves fatty, resinous, and other matters, and precipi- tates the cantharidin. The precipitate is thrown on a filter, washed with bisulphide of carbon, and recrystallized from chloroform. The same process, omitting the final recrystallization, may be used for the quantitative estimation of cantharidin in cantharides. The aver- age quantity found is from four to five parts in one thousand. Can- tharidin is readily soluble in warm glacial acetic acid (Tichborne) and in acetic ether. Massing and Draggendorf consider cantharidin to be an anhydride (OgHgOg), and that with the elements of water it forms cantharidic acid (Il 2 C 5 Hg 02 ). A cantharidate of potassium has the composition KHCdllgO.^. 35 410 RESINOID SUBSTANCES. QUESTIONS AND EXERCISES. 841. How do volatile oils differ chemically from fixed oils ? 842. What are the general chemical characters of volatile oils ? 843. Describe the usual process by which volatile oils are obtained. 844. Mention the differences in composition between the volatile oils of Antliemis nohilis and Matricaria chamomilla, 845. Give the systematic name of oil of horseradish. 846. State the general composition of the oil of lemon, lime, ber- i gamot, citron, and cedra. j 847. Name the constituents of oil of cloves. 848. In what respect does oil (or otto) of roses differ from other i volatile oils ? ! 849. To what class of substances do the constituents of oil of rue belong ? 850. How does natural turpentine differ from the turpentine of trade ? 851. With what object is commercial turpentine rectified? 852. How is camphor oil related to camphor ? >•53. In what respects do Borneo or Sumatra camphor and cam- phor oil differ from the corresponding products of Japan and China ? 854. What is the nature of cantharidin ? RESINOID SUBSTANCES. | RESINS, OLEO-RESINS, GUM-RESINS, BALSAMS. 1 Resins occur in plants generally in association with volatile oils. ( They closely resemble camphors or stearoptens, but are not volatile, ( and differ from oils and fats mainly in being solid and brittle. Oleo- I resins are mixtures of a resin and a volatile oil. Gum-resins are i mixtures of a resin or oleo-resins and gum. Balsams are commonly described as resins or oleo-resins which yield benzoic or cinnaniic acid ; but oleo-resins containing neither of these acids are often termed balsams, e. g., balsam of copaiva and Canada balsam. Resins. — 1. Resin, rosin, or colophony [Resina, B. P. and U. S. I P.) is the type of this class. Its source is the oleo-resin or true tur- | pentine of the conifers, a body which by distillation yields spirit of | turpentine and a residuum of rosin. “ Brown” and “ White” rosin I are met with in trade. 'Hie former is the residue of American, the ! latter of Bordeaux turpentine (from Pinus Abies, etc., and Pinus ,j Maritima) respectively, llie chief constituents of brown resin are i pinic acid (HC 2 oH.^ 0 . 2 ) and sylvic acid, identical in composition, ; but differing in properties [vide Isomerism), the former being soluble j and the latter insoluble in cold spirit of wine. White resin or ; “ galipot” is chiefly pimaric acid, also isomeric with pinic acid. Piiiic acid heated yields colophonic or colopholic acid. Among the , products of the destructive distillation of resin, Tichborne has re- : cently found “ colophonic hydrate'" (CjoH 2203 ,H 20 ), a white inodor- : OLEO-RESINS. 411 ous crystalline substance, and by depriving this of water obtained white crystalline colopliomne Resin is soluble in oil of turpentine. Contact with sulphuric acid immediately colors it strongly red. It is a constituent of eight of the fourteen Plasters (Emplastra) of the British Pharmacopoeia. 2. Armcm, the chief acrid if not the only active principle of Arnica {Arnicce Radix, B. P., Arnicce Flores, U. S. P.), is a resin. 3. Cannahin, said to be the active principle of Indian Hemp ( Cannabis Indica, B. P., Ex~ tractum Cannabis, U. S. P.), is usually described as a resin. 4. Capsicum-fruit contains resin (p. 351). 5. Castorin, a resinous matter, is the name given to the chief constituent of Castor ( Cas- toreum), B. P. and U. S. P.), the dried preputial follicles and in- cluded secretion of the Beaver ( Castor Fiber). 6. Ergotin is a very active resinoid constituent of Ergot [Ergota, B. P. and U. S. P.), or “the sclerotium (compact mycelium or spawn) of Claviceps pur- purea, produced within the paleae of the common rye, Secale cerealei^ 7. Guaiacum-resin is a mixture of several substances (p. 369). 8. Jalap-resin (p. 369). 9. Kousso [Cusso, B. P.) is said to owe its anthelmintic property to a neutral bitter acrid resin. 10. Mastic [Mastiche, B. P. and U. S. P.) is a resinous exudation obtained by incision from the stem of the Mastic or Lentisk tree. Nine- tenths of Mastic i^mastichic acid ( 020 ^ 81 ^ 2 )? ^ resin soluble in alcohol ; the remaining tenth, masticin (0.,oH3^0) a tenacious elastic resin. 11. Mezereon, the dried bark [Mezerei Cortex, B. P. and U. S. P.) of Daphne mezereum, Mezereon, and Daphne laureola. Spurge Laurel, owes its acridity to a resin. 12. Pepper contains a resin (p. 353). 13. Burgundy Pitch [Pix Burgundica, B. P. and U. S. P.) is the melted and strained exudation from the stem of the Spruce Fir, Abies Excelsa. The term Burgundy is a misnomer, the resin never having been collected at or near Burgundy ; Finland, and to a smaller extent Baden, and Austria being the countries whence it is derived. Its constituents closely resemble those of common Kesin. It is often adulterated and imitated by a mixture of resin with palm-oil, water, etc., from which it may be readily distinguished by its duller yellow color, highly aromatic odor, greater solubility in alcohol, and almost complete solubility in twice its weight of glacial acetic acid (Han- bury). 14. Podophyllum-resin (p. 351). 15. Pyrethrin\^\\\^ name of the acrid resinous active principle of Pellitory-root [Pyrethri Radix, B. P.). 16. The resins of Rhubarb have already been alluded to in connection with Chrysophanic acid (p. 300). 17. Rott- lerin is the name given by Anderson to a crystalline resin from Kamala (Kamala, B. P.), the minute glands that cover the capsules of Rottlera iinctoria : to this, and, apparently, allied resins, Kamala owes its activity as an anthelmintic. Oleo-resins. — 1 . Copaiva {Copaiba, B. P. and U. S. P.) is a mixture of about 40 per cent, of essential oil ( 0 ^ 51124 ), with two or more per cent, of brown soft resin, and 50 or more of a yellow dark resin termed Copaivic acid ( 020 ^ 30 ^ 2 )* Copaiva heated with a fourth of its weight of the official carbonate of magnesium yields a transparent fluid, owing to the formation of copaivate of magnesium and solution of this soap in the essential oil. With an equal weight of the car- 412 RESINOID SUBSTANCES. bonate enongli soap is produced to take up the whole of the essential oil, and form a mass capable of being rolled into pills. A much smaller quantity of calcined magnesia, as might be expected, effects the same result ; but more time, often several days, is required before complete reaction is effected. Quicklime has a similar effect. Per- haps carbonate reacts more quickly because of its fine state of divi- sion and admixture of hydrate — in which case hydrates of calcium and magnesium may be expected to act better than the calcined pre- parations, and in much smaller quantity than carbonate of magnesium. Copaiva is soluble in its own bulk of benzol, and, unlike, 2, Wood- oil, a similar oleo-resin from the Dipterocarpus turbinatus, does not become gelatinous when heated to 270^ F. Copaiva, also, is not fluorescent. 3. Elemi [Elemi, B. P.) is an exudation from an un- known tree (probably Canartum commune). It consists of volatile oil with 80 or more per cent, of two resins, the one (C20H32O2) solu- ble in cold alcohol, the other (C20H33O) almost insoluble. 4. Wood- Tar [Ptx Liquida, B. P. and U. S. P.) is a mixture of several resi- noid and oily bodies (amongst others Creasote, p. 392) obtained by destructive distillation from the wood of Pinus sylvestris and other pines. When heated it yields a terebinthinate oil and a residue of pitch. 5. Turpentines. These oleo-resins have been mentioned in connection with oil of turpentine, their volatile, and resin, their fixed constituent. 6 . Common Frankincense ( Thus Americanum^ B. P.) is the concrete turpentine of Pinus tceda. 7. Canada Balsam [Terehinthina Canadensis, B. P.) is the turpentine or oleo-resin of the Balm of Gilead Fir [Abies bahamea). 8. Sumbul-root (Sum- but Radix, B. P.) seems to owe its stimulating property to two oleo-resins, one soluble in ether, the other in alcohol. 9. Oleo-resin of Lupuliii (U. S. P.) is an ethereal extract of the yellow powder [Lupulina, U. S. P.) attached to the small nuts at the base of the scales which form the aggregate fruit of the Hop [Humidus Lupu- lus). It contains essential oil of hop and oxidized oil or resin. Oleoresince Capsid, CubebcB, Piperis, and Zingiberis are also offi- cial in the United States Pharmacopoeia. 10. Pix Canadensis, U. | S. P., is the concrete juice of Abies Canadensis. i Gum-resins. — 1. Ammoniacum [Ammoniacum, B. P. and U. S. P.) is an exudation from the Dorema Ammoniacum. It contains | nearly 20 per cent, of gum and about 70 of resin (C^oH^QOy — John- 1 ston). 2. Assafotiida [Assafoetida, B. P.) is a gum-resin obtained, [ by incision, from the living root of Narthex assafoetida. It contains t from 50 to 70 per cent, of resin, 25 to 30 per cent, of gum (about two- \ thirds arabin, one-third bassorin, p. 97), and 3 to 5 per cent, of vola- tile oil. 3. Gamboge [Cambogia, B. P. and U. S. P.) is obtained from the Garcinia morella. AVhen of best quality it contains from 1 ) 20 to 25 per cent, of gum, and 80 to 75 per cent, of a resin termed jl gambogic acid (C20H23O4). 4. Galbanum [Galbanum, B. P. and ;! U. S. P.) contains from 20 to 25 per cent, of gum, and about 65 per !• cent, of resin (G^yH^^O^), and 3 or 4 per cent, of volatile oil. 5. | Myrrh [Myrrha, B. P. and U. S. P.), an exudation from the stem |i of Balsamodendron myrrha, contains about half its weight of solu- |t ble gum (probably arabin), 10 per cent, of insoluble gum (probably |; BALSAMS. 413 bassorin), of volatile oil, and about 25 per cent, of resin (rayrrhic acid). 6. Scammony (p. 371). Gum-resins need only be finely powdered and rubbed in a mortar with water to yield a medicial emulsion, in which the fine particles of resin are held in suspension by the aqueous solution of gum. Balsams. — 1. Benzoin [Benzoinum, B. P. and U. S. P.) is ob- tained from incisions of the bark of Styrax benzoin. It contains 12 to 15 per cent, of benzoic acid (p. 298), about 50 per cent, of a resin (a) soluble in ether, 25 to 30 per cent, of a resin (d) soluble in alcohol only, and 3 to 4 per cent, of a resin (y) soluble in solution of carbonate of sodium. The a resin is considered to be a compound of the 3 (C^qH^^Oc,) and the y (C30H4QO5). The balsams of Peru, Tolu, and Storax differ from benzoin in containing cinnamic (p. 407) in place of benzoic acid ; hence they yield, by oxidation, hydride of benzoyl (oil of bitter almonds). 2. Balsam of Peru [Balsamum Peruvianum, B. P. and U. S. P.), from the Myroxylon Pereiras, is a mixture of 70 per cent, of oily with about 23 of resinous matter, and 6 per cent, of cinnamic acid. The oil, by fractional distillation in an atmosphere of carbonic acid gas and under diminished pres- sure, furnishes benzylic alcohol (C-H^HO), benzoate of benzyl (C7H-C7H.O.J, and cinnamate of benzyl . (Kraut). By action of alcoholic solution of potash it yields benzoate and cin- namate of potassium, and benzylic alcohol; also cinnamic alcohol (C9H9HO), otherwise known as 'peruvine ov sty rone ; it also often holds in solution metacirtnamSin or styracin (C,3Hjg02), isomeric with hydride of cinnamyl (CgH^OH). The resin of balsam of Peru seems to result from the action of moisture on the oil. The constitu- ents of Vanilla, U. S. P., the prepared unripe pods of a plant, some- what resemble those of Balsam of Peru. The crystals often found on vanilla are a weak acid substance having the formula (Carles). 3. Balsam of Tolu [Balsamum Tolutanum, B. P. and U. S. P.) is an exudation from incisions in the bark of Myroxylon toluifera ; it closely resembles balsam of Peru, but is more suscepti- ble of resinification. Old hard balsam of tolu is a convenient source of cinnamic acid, which is extracted by the same process as that by which benzoic acid is obtained from benzoin, namely, ebullition with alkali, filtration, and precipitation by hydrochloric acid. 4. Storax is an oleo-resin obtained from the Liquidambar orientale. It con- tains a volatile oil term styrol (C^Hg), cinnamic acid, styracin, and a soft and a hard resin. Styrol differs from similar hydrocarbons in being converted into a polymeric solid termed metastyrol or draconyl on the mere application of a temperature of about 400^ F. For medicinal use, storax [Styrax Prceparatus, B. P. and U. S. P.) is purified by solution in alcohol, filtration, and removal of the alcohol by distillation. Caoutchouc or India-rubber, and Gutta Percha. Caoutchouc is the hardened juice of Hevea [Siphonia] Brazili- ensis, Castilloa elastica, Urceola elastica. Ficus elastica, and other plants (Collins). Heated moderately with sulphur it takes up 2 or 3 per cent., and forms vulcanized India-rubber ; at a higher tem- 35 * 414 COLORING - MATTERS. perature a hard horny product, termed ebonite or vulcanite, results. Gutta Percha (U. S. P.) is the concrete drop or juice of the percba (Malay) tree, the Isonandra gutta,. smd of other Sapotaceous plants, j It is soluble in chloroform (Liquor Gutta-percha, U. S. P.), benzoyl, and essential oils. White gutta percha is obtained by precipitating a solution of the ordinary gutta percha in chloroform by alcohol, washing the precipitate with alcohol, and finally boiling in water and moulding into desired form while still hot. These two elastic substances, in the pure state, are hydrocarbons (xCgH^), usually slightly oxidized. QUESTIONS AND EXERCISES. 855. Distinguish between resins and camphors. Mention the points of difference of resins, oleo-resins, gum-resins, and balsams. 856. Name the constituents of common Resin. 857. Enumerate some official articles of which the active constitu- ents are resins. 858. Give the chief distinguishing characters of Burgundy Pitch. 859. What is the average proportion of oil in Copaiva ? 860. Explain the effect of magnesia or lime on copaiva. 861. State the nature of Wood-tar. 862. Why do Ammoniacum, Assafoetida, Gamboge, Galbanum, and Myrrh give an emulsion by mere trituration with water ? 863. In what respect does Benzoin differ from the Balsams of Peru, Tolu, and Storax ? 864. What is the chemical nature of India-rubber and Gutta Percha ? 865. How is India-rubber vulcanized and converted into ebonite or vidcanite ? COLORING-MATTERS. The animal, vegetable, and mineral kingdoms abound in sub- Ij stances or pigments which powerfully decompose light, absorbing |j certain of its constituent colors, and reflecting some others. Thus, j] for example, most leaves contain a body termed chlorophyll, which j| has the property of absorbing red light and reflecting green ; these [. reflected rays entering the eye of an observer, and striking on the fi retina (the expanded extremity of the optic nerve), always commu- n nicate the same impression to the brain ; in popular language the n leaf is said to be green. Art has added largely to the number of ; natural coloring-matters. , Yellow. — I. Chrome-yellow occurs in more than a dozen shades (see Lead, chromate of). 2. Fustic or yellow wood is the wood of '• the Phus cotinus. 3. Gamboge (see Gamboge). 4. Ochre is met ! with of many tints, under the names of yellow ochre, gold yellow, ’ gold earth or ochre, yellow sienna, Chinese yellow. It is chiefly ; COLORING-MATTERS. 415 a mixture of oxyhydrates of iron with alumina and lime. 5. Orpt- ment is a sulphide of arsenicum ( As.^Sg). 6 . Persian berries or Avig- non grains contain a principle termed chrysorhamnin They are the product of the Rliamnus infectorius. 1. Purree or Indian yellow is said by Stenhouse to owe its color to purrate or euxanthate of magnesium (MgG\ 2 H 34022 ). 8 . Quercitron is the bark of Quercus tinctoria^ U. S. F., or Black Oak. It contains the yellow glucoside, quercitrin (Oj^H,gOio,H20). 9. Rhubarb (see Chrysophanic acid, p. 300). 10 Saffron [Crocus, B. P. and U.S. P.), the dried stigma and part of the style of Crocus sativus, yields saffranin or polychroite, a yellow principle whose chemistry is but little known. 11 . Turmeric, the rhizome of Curcuma longa, owes its yellow color to curcumin, a resinous matter, the formula of which is said by Daube to be OioHio^s? and by Iwanof C^H^O. Possibly two yellow pigments are present. 12 . Weld [Reseda luteola) con- tains a durable yellow matter termed luteolin 13. Picric or carbazotic acid (p. 392) is a very powerful yellow dye. 14. Dried and powdered carrots yield to bisulphide of carbon a yellow coloring- matter, “ carrotin,” which is obtained on evaporating the solvent. It is said to be used in coloring butter. Red. — 1. Alkanet, the root of Alkanna tinctoria, Tausch, An- cliusa tinctoria, yields anchusin (C 35 II 40 O 8 ), a resinoid matter soluble in oils and fats. 2. Annato, Arnatto, or Arnotto, a paste prepared from the seeds of Bixa orellana, contains bixin, an orange- red, and orellin, a yellow principle. 3. Brazil-wood [ Ccesalpinia brasiliensis) furnishes brezilin, the basis of several lakes. Sapan- wood and Cam-ivood probably contain the same substance. 4. Cin- nabar, Chinese red. Vermilion, or Paris red is mercuric sulphide. 5. Chrome-red is an oxychromate of lead. 6. Cochineal (p. 300). 7. Madder, the root of Rubia tinctorum, powdered and treated with sulphuric acid and acidulated water to effect the removal of earthy and other inert matters, furnishes a residual powder termed garancin. Garancin yields to pure water alizarin (Cj^Hj^O^, 3 H 2 O), the red, neutral, crystallizable coloring-matter of madder. Alizarin does not exist ready formed in the plant, but is derived, by fermen- tation, from rubian, a yellowish resinoid substance. Alizarin is now produced artificially from anthracene, one of the solid constituents of coal-tar. 8. Mulberry-juice [Mori Succus, B. P.) contains a violet-red coloring-matter which has not been chemically examined. 9. Red lead (p. 187). 10. Red oxide of iron, of shades varying from light to brown red, is found native. The common names of it are Armenian bole, Berlin-red, colcothar, English red, red ochre, burnt ochre, red earth, terra di sienna, mineral purple, stone red, and Indian red. 11. Red Sandal-wood [Pterocarpi Lignum, B. P. and U. S. P.), the billets and chips of Pterocarpus santalinus, owes its color to santalin (CigHjg 03 ), a resinoid matter. 12 . Red-Poppy Petals [Rhcedos Petula, B. P.), from the papaver rhceas, contain a red coloring principle which has not yet been isolated. 13. Red- Rose Petals [Rosce Gallicce Petala, B. P. and U. S. P.) also yield a red substance which has not been analyzed. 14. Safflotver, Dyer's Saffron or Bastard Saffron, the florets of Carthamus tine- 416 COLORING-MATTERS. torius, contains an unimportant yellow dye, and 5 per cent, cartha- min an uncrystallizable red dye, the pigment of the old ])ink saucers. Carthamin seems to possess acid characters, and (like silicic acid and other substances) to be soluble in water for a certain time after liberation from its alkaline solution ; for fabrics are dyed with safflower by immersion in a bath made of an infusion in dilute alkali neutralized by citric acid immediately before use, the cartha- niin probably penetrating the cells and vessels of the fibres in a solu- ble form, there becoming insoluble and imprisoned and thus giving permanent color to the wool, silk, or other material. Mixed with French chalk, carthamin is used as a cosmetic under the name of vegetable rouge — carmine being animal rouge, and red oxide of iron mineral rouge. 15. Lac-dye a cheap form of cochineal, and is also yielded by a species of Coccus. 16. Logwood [HcBmatoxyli Lignum, B. P.) contains a yellow substance, licematoxylin OgH.^O or SH^O), which, under the influence of air and alkali, assumes an intense red color. 17. Red enamel colors, for glass- staining and ceremic operations, are produced either by cuprous sili- cate or purple of Cassius (p. 218). Blue. — 1. Cobalt oxide precipitated in combination or admixture with alumina or phosphate of calcium forms Thenar d's blue, cobalt- blue, Hoffne fs blue, and cobaltic ultramarine. 2. Smalt, Saxony blue, or King's blue, is rough cobalt glass in fine powder (p. 207). 3. Copper-blue, mountainMue, and English or Hambro' blue are carbonates or oxycarbonates of copper. 4. Indigo (p. 258). 5. Lit- mus, lichen-blue, turnsole, orchil or archil, and cudbear products of the action of air and alkalies on certain colorless principles, as orcin (0711^02), derived from different species of lichen — Roccella, Variolaria, and Lecanora. 6. Prussian blue (p. 303) and Turn- bidVs blue [\). 304), the ferro- and ferridcyanides of iron, are met with under the names of Erlangen, Louisa, Saxon, Paris, or Berlin blue. 7. Ultramarine is made on a large scale by roasting a mix- •ture of fine white clay, carbonate of sodium, sulphur, and charcoal. Its constitution is not well made out. Acids decompose it, sulphu- | retted hydrogen escaping. j Green. — 1. Cupro-arsenical green pigments (p. 152). 2. Chlo- j rophyll. Leaf-green, or Chromule. A method of extracting chlo- j rophyll is given under “ Extracts,*' vide Index. It is resinoid, soluble j in alcohol and ether, insoluble in water, and, according to Fremy, r consists of a blue substance, phyllocyanin (Og^IIfigN^Oj^ ?), and a j jeWovf, phylloxanthin ; the yellow tints in fading autumnal leaves, | he says, are due to the latter principle, the former being the first to j fade. 3. Sap-green, buckthorn-, vegetable-, or bladder-green is ob- j tained by evaporating to dryness a mixture of lime and the juice j [Rliamm Succus, B. P.) of the berries of the Buckthorn [Rhamnus j catharhcus). It is soluble in water, slightly in alcohol, and insolu- 1 ble in ether and oils. 4. Green ultramarine is made by a process ! similar to that for blue ultramarine. 5. Mixtures of blue and yellow ( pigments and dyes are common sources of green colors. 6. Glass ■ and earthenware are colored green by oxide of chromium and black | oxide of copper. 1 COLORING-MATTERS. 417 Brown. — 1. Umber, Sienna, or Chestniit-hrown is found native. By heat it is darkened in tint, and is then known as burnt umber. It is a mixture of oxide of iron, silica, and alumina. 2. Sepia is a dried fluid from the ink-bag of cuttlefishes {Sepiadce) ; by its ejection into adjacent water the animal obtains opportunity of escape from enemies. 3. Catechu (p. 318) furnishes a brown coloring-matter. Black. — 1. Blacklead (p. 26), bone-black (p. 95), or ivory-black, and lampblack, the latter a deposited soot from incomplete com- bustion of resin and tar, are varieties of carbon. 2. Burnt sugar or caramel (p. 364). 3. Indian ink is usually a dried mixture of fine lampblack and size, or thin glue. 4. Black ink is essentially tannates and gallates of iron suspended in water containing a little gum in solution. 5. Printer's ink is well boiled linseed or other oil, mixed with good lampblack, vermilion, or other pigment. 6. Black dyes are of the same nature as ink. White Pigments. — 1. Chalk or Whiting (p. 94). 2. French chalk, steatite, or soapstone, a silicate of magnesium. 3. Heavy white (p. 87). 4. Pearl-vdiite (p. 224). 5. Plaster of Paris (p. 90). 6. Starch (p. 355). 7. White-lead (p. 185). 8. /Anc-white (p. 113). 9. Oxides of tin and zinc and phosphate of calcium are employed for giving a white opacity to glass. Aniline Colors. Coal-tar colors. — Within the last ten years nearly every shade of color seen in the animal or vegetable kingdoms has been successfully imitated by certain dyes and pigments primarily derived from a mineral, coal. Coal distilled for gas furnishes tar or gas-tar. Coal-tar contains some aniline ; but especially it contains a liquid convertible into aniline, namely benzol (C^-H^H), first discovered by Faraday in compressed oil-gas. From aniline, by oxidation, Bunge obtained the violet color-reaction, the body producing which Perkin afterwards studied and isolated, and manufactured under the name of mauve. Aniline-red [fuchsine, magenta, or rosaniline), aniline-yellow, aniline-green, aniline-blue, and, in short, aniline-dyes, lakes, and pigments of every hue of the rainbow, are now common articles of trade. Their application has revolutionized the arts of the dyer and color printer. QUESTIONS AND EXERCISES. 866. Explain the production of color. 867. Mention the chief yellow coloring-matters. 868. What is annatto ? 869. Name the colorific constituent of madder. 870. State the source of Litmus. 871. Distinguish between Prussian blue and Turnbulhs blue. 872. How is blue ultramarine obtained ? 873. Describe the coloring principle of green leaves. 874. By what agents is glass colored green ? 875. Whence is sepia obtained? 876. Describe the chemistry of black ink. 877. Write a few sentences on aniline colors. 418 CHEMICAL TOXICOLOGY. CHEMICAL TOXICOLOGY. In cases of criminal and accidental poisoning, the substances pre- sented to the chemical analyst for examination are usually articles of food, medicines, vomited matters, or the liver, kidney, intestines, stomach and contents, removed in course of post-mortem examina- tion. In these cases some special operations are necessary before the poison can be isolated in a state of sufficient purity for the applica- tion of the usual tests; for in most instances the large quantity of animal or vegetable, or, in one word, organic matter present pre- vents or masks the characteristic reactions on which the tests are founded. These operations will now be described ;* they form the chemical part of the subject of toxicology {ro^vxov, toxicon, poison, and ^6yo^, logos, discourse). Substances occurring in the form of an apparently definite salt or unmixed with organic matter need no special treatment, they are analyzed by the ordinary methods already given, attention being restricted to poisonous compounds only. Examination of an organic mixture suspected to con- tain: Mercury, ArsenicuxM, Antimony, Lead, Copper, OR Zinc; Sulphuric Acid, Nitric Acid, Hydrochloric Acid, Oxalic Acid, or Hydrocyanic Acid; Caustic Alkalies; Strychnia or Phosphorus; Morphia or OTHER Poisonous Alkaloids. Preliminary Examination. Odor.^ Appearance.^ Tante . — Smell the mixture, with the view of ascertaining the presence or absence of any nota- ble quantity of free hydrocyanic acid. Look carefully for any small solid particles, such as arsenic, corrosive subli- mate, or verdigris, and for any appearance which may be regarded as abnormal, any character unusual to the coffee, tea, beer, medicine, vomit, coats of stomach, kidney, liver, or other organ, tissue, or solid matter under examination. If liquid or semifluid, taste the mixture, or add to a small portion some solution of carbonate of sodium, with the view of ascertaining by excessive sourness or strong effer- vescence the presence of any large, poisonous quantity of sulphuric, nitric, or h 3 'drochloric acid. If so excessively alkaline as to require the addition of a veiy large quantity * Materials for these experiments are readily obtained for educa- tional purposes by dissolving the poison in infusions of tea, coffee, porter, or in water to which some mucilage of starch or linseed-meal, pieces of bread, potato, and fat have been added. MERCURY, ARSENICUM, ANTIMONY, ETC. 419 of acid before neutralization is effected, a noxious quantity of a corrosive or caustic alkali is present. Special insti'uctions may induce the operator to suspect the presence of one particular poison. Direct examina- tion for the latter may then be made, either at once, if the substance has an aqueous character, or when filtration or treatment with warm hydrochloric or acetic acid has afforded a more or less colorless liquid. Fluids. — A vomit or the contents of a stomach, if set aside in a long narrow vessel (test-glass or ale-glass), or, better, exposed on a filter during a night, will often yield a more or less clear limpid portion at the bottom or top of the solid matter. This fluid (separated by a pipette or otherwise) will sometimes respond to tests without further preparation, and always requires less preparatory treatment than a semisolid mixture. If none passes through a filter, a portion often collects in the upper part. General procedure . — If the preliminary examination does not indicate the method to be pursued, proceed as follows, treating a portion (not more than one-fourth) of the mixture for the poisonous metals, another for the acids, and a third for alkaloids, reserving the remainder for any special experiments which may suggest themselves in the course of analysis. Examination for Mercury.^ Arsenicum.^ Antimony^ Lead^ Copper^ Zinc. If a liquid, acidulate with hydrochloric acid and boil for a short time. If solid or semisolid, cut up the matter into small pieces, add enough water to form a fluid mixture, stir in ten or twenty per cent, of ordinary liquid hydrochloric acid, and boil until, from partial aggregation and solution of tlie solid matter, filtration can be easily effected. Heat a portion of the clear liquid with a thin piece of bright copper or copper gauze, about an inch long and a quarter of an inch broad, for about ten or twenty minutes ; metallic mercury.^ arsenicum^ or antimony will be deposited on the copper, darkening it considerably in color. Pour off the liquid from the copper, carefully rinse the latter with a little cold water, dry the piece of metal by holding it over or near a flame (using fingers, not tongs, or it may become sufficiently hot for loss of mercury or arsenicum to occur by A^olatilizatioii), introduce it into a narrow test- tube or piece of glass tubing closed at one end, and heat 420 CHEMICAL TOXICOLOGY. the bottom of the tube in a flame, holding it horizontally that the upper part of the tube may be kept cool, and par- tially closing the mouth with the finger to prevent escape of vapor. Under these circumstances an}’’ Mercury will volatilize from the copper and condense on the cool part of the tube in a ring or patch of white sublimate, readily aggregating into visible globules on being pressed b}" the side of a thin glass rod inserted into the tube ; Arsenicum will volatilize from the copper, and, absorbing oxygen from the air in the tube, condense on the cool part of the glass in a ring or patch of white sublimate of arsenic (gray or even darker if much arsenicum as well as arsenic be pre- sent), not running into globules when rubbed, but occur- ring in small crystals, the characteristic octahedral form of which is readily seen by aid of a good hand lens, or the lower part of a microscope ; Antimony volatilizes from the copper, if strongly heated, and, absorbing ox 3 'gen, immedi- ately condenses as a slight white deposit close to the metal. Confirmatory Tests. — 1. Nothing short of the production of globules should be accepted as evidence of the presence of mercury. It will usually have existed as corrosive sublimate. 2. To confirm indications of the presence of arsenicum, a portion of the acid liquid may be subjected to the hydrogen tests (pp. 149, 151) ; or the tube containing the white crystalline arsenic may be broken, and the part on which the sublimate occurs boiled for some time in water, and the hydrosulphuric-acid, ammonio-nitrate-of-silver, and ammonio-sulphate-of-copper tests (pp. 151, 153) applied to the aqueous solution. 3. For antimony, a portion of the acid liquid must always be intro- duced into the hydrogen-apparatus with the usual precautions. ( Vide I p. 160.) •: For Lead and Copper^ pass hj^drosulphuric acid gas through the clear acid liquid for some time, warming the liquid if no precipitate is produced, or diluting and par- j tially neutralizing the acid by ammonia if much acid has been added. Collect on a filter any black precipitate that |i may have formed ; wash, dissolve in a few drops of aqua ! regia, dilute, and apply the tests, such as ammonia for copper, sulphuric acid for lead, and any other of the or- r dinary reagents (pp. 168, 189). Copper may often be at once detected in a small quantity of j acidulated liquid by immersing the point of a penknife or a piece of j bright iron wire — a deposit of copper, in its characteristic color, i, quickly or slowly appearing, according to the amount present (p. ji 168). l! MINERAL ACIDS, OXALIC ACID, ETC. 421 Zinc, — To the acid liquid through which sulphuretted hydrogen has been passed, add excess of ammonia (or to the original acid fluid add excess of ammonia, and then sulphydrate of ammonium) ; a precipitate falls which may contain alumina, phosphates, and zinc ; it is usually black- ish from the presence of sulphide of iron. Collect the precipitate on a filter, wash, dissolve in a little hydro- chloric acid, add a few drops of nitric acid, boil, pour in excess of ammonia, filter, and test the filtrate with sulphy- drate of ammonia — a white precipitate indicates zinc. Examination for Mineral Acids,^ Oxalic Acid^ or Hydrocyanic Acid. To detect Hydrochloric.^ Nitric.^ or Sulphuric Acid in any liquid containing organic matter, dilute with water and apply to small portions the usual tests for each acid, disregarding indications of small quantities. (Vide pp. 240, 256, m.) Excessive sourness, copious evolution of carbonic acid gas on the addition of carbonate of sodium, and abundant evidence of acid on applying the various tests to small portions of the fluid presented for analysis, collectively form sufficient evidence of the occurrence of a poisonous amount of either of the three common mineral acids. Small quantities of the hydrochloric, nitric, and sulphuric radicals occurring as metallic salts or acids, are common normal constituents of food, hence the direction to disregard insignificant indications. If the fluid under examination is a vomit or the contents of a stomach, and an antidote has been administered, free acid will not be found, but, instead, a large amount of corresponding salt. For Oxalic Acid., filter or strain a portion of the liquid, if not already clear, and add solution of acetate of lead so long as a precipitate occurs ; collect the precipitate, which is partly oxalate of lead, on a filter, wash, transfer it to a test-tube or test-glass, add a little water, and pass hydro- sulphuric gas through the mixture for a short time ; the lead is thus converted into the insoluble form of sulphide, while oxalic acid is set free in the solution. Filter, boil to get rid of hydrosulphuric gas, and apply the usual tests for oxalic acid (see p. 282) to the clear filtrate. The contents of a stomach containing oxalic acid are often of a dark-brown color with a tinge of green (altered blood and mucus), and the viscid mixture generally, though slowly, affords some clear, limpid, almost colorless liquid by filtration on standing. For Hydrocyanic Acid.^ the three chief tests may be ap- 36 422 CHEMICAL TOXICOLOGY. plied at once to the liquid or semiliquid organic mixture, whether it has an odor of hydrocyanic acid or not. First: half fill a small porcelain crucible with the material, add eight or ten drops of strong sulphuric acid, stir gently with a glass rod, and invert ever the mouth of the crucible a watch-glass moistened with a small drop of solution of nitrate of silver; a white film on the silver solution is probably cyanide of silver, formed by the action of the gaseous hydrocy^anic acid on the nitrate of silver. Second : prepare a small quantit}^ of the organic mixture as before, slightly moistening the centre of the watch-glass with solution of potash; here again the heat generated by the action of the strong acid is sufficient to volatilize some of the hydroc^^anic acid, which, reacting on the potash, forms cyanide of potassium. On removing the watch-glass and stirring into it successively solution of a ferrous salt, a ferric salt, and hydrochloric acid, flocks of prussian blue are produced if hydrocyanic acid is present. Third: pro- ceed as before, moistening the watch-glass with sulphydrate of ammonium ; after exposure to the hydrocyanic gas for five or ten minutes, add a drop of solution of ammonia, evaporate to dryness at a low temperature, and add a drop of hydrochloric acid and of solution of perchloride of iron ; a blood-red color, due to sulphocj^anate of iron, is pro- duced if cyanogen is present. If the above reactions are not well marked, the organic mixture may be carefully and slowly distilled in a small retort, the neck of which passes into a bottle .and dips beneath the surface of a little w^ater at the bottom of the bottle, and the reagents then applied to separate portions of the distillate. The examination of organic mixtures for hydrocyanic acid must be made without delay, as the poison soon begins to decompose, and in a day or two is usually destroyed. Examination for Phosphorus. A paste containing phosphorus is commonly employed for destroy- ing vermin. In cases of poisoning the phosphorus is commonly in suf- ficient quantity to be recognized by its characteristic unpleasant smell. A stomach in which it occurs not unfrequently exhibits slight luminosity if opened in a dark room. When the phosphorus is too small in quantity or too much diffused to afford this appearance, a portion of the material is placed in a flask, water acidulated by sulphuric acid added, a long wide glass tube fitted to the neck of the flask by a cork, and the mixture gently boiled. If phosphorus is prcvsent (even I part in 2,000,000, according to De Try) the top of the column of steam as it condenses in the tube will appear distinctly STRYCHNIA AND MORPHIA. 423 phosphorescent when viewed in a dark room. From its liability to oxidation phosphorus cannot be detected after much exposure of an organic mixture to air. Examination for Strychnia and Morphia. Strychnia . — If solid or semisolid, digest the matter with water and about 10 per cent, of hydrochloric acid till fluid, filter, evaporate to dryness over a water-bath. If the or- ganic mixture is already liquid, it is simply acidulated with hydrochloric acid and evaporated to dryness. The acid residue is next treated with spirit of wine as long as any- thing is dissolved, the filtered tincture evaporated to dry- ness over the water-bath, and the residue digested in water and filtered. This slightly acid aqueous solution must now be rendered alkaline by ammonia, and well shaken in a bottle or long tube with about half an ounce of chloroform, and set by till the chloroform has subsided. The chloro- form (which contains the strychnia) is then removed by a pipette, the presence of any aqueous liquid being carefully avoided, and evaporated to diyness in a small basin over a water-bath, the residue moistened with concentrated sul- phuric acid, and the basin kept over the water-bath for sev^eral hours. (It is highly important that the sulphuric acid used in this operation should be free from nitrous compounds. Test the acid, therefore, by adding powdered sulphate of iron, which becomes pink if nitrous bodies are present. If these are found, the acid should be purified by strongly heating with sulphate of ammonium, seventy or eighty grains to a pint.) The charred material is ex- hausted with water, filtered, excess of ammonia added, the filtrate shaken with about a quarter of an ounce of chloroform, the mixture set aside for the chloroform to separate, and the chloroform again removed. If, on evapo- rating a small portion of this chloroform solution to dry- ness, adding a drop of sulphuric acid to the residue, and warming, any darkening in color or charring takes place, the strychnia is not sufficiently pure for chemical detection; in that case the rest of the chloroform must be removed by evaporation, and the residue redigested in warm sul- phuric acid for two or three hours. Dilution, neutraliza- tion of acid by ammonia, and agitation witli chloroform are again practised, and the residue of a small portion of the chloroform solution once more tested with sulphuric acid. If charring still occurs, the treatment must be repeated a 424 CHEMICAL TOXICOLOGY. third time. Finally a part of the chloroform solution is taken up by a pipette, and drop after drop evaporated on one spot of a porcelain crucible-lid until a fairly distinct dry residue is obtained. A drop of sulphuric acid is placed on the spot, another drop placed near, a minute fragment of red chromate of potassium placed in the second drop, and when the acid has become tinged with the chromate, one drop drawn across the other ; the char- acteristic evanescent purple color is then seen, if strychnia is present. Other tests {vide p. 248) may be applied to similar spots. This is Girdwood and Kogers’s method for the detection of strych- nia when mixed wnth organic matter. It is tedious but trustworthy, and, though apparently complicated, very simple in principle ; thus: strychnia is soluble in acidulated water or alcohol, or in chloroform, readily removed from an alkaline liquid by agitation with chloroform, and not charred or otherwise attacked when heated to 212^ F. with sulphuric acid : much of the organic matter of the food is insoluble in water ; of that soluble in w^ater, much is insoluble in alcohol ; and of that soluble in both menstrua, all is charred and destroyed by warm sulphuric acid in a shorter or longer time. Morphia^ and the Meconic Acid with which it is associ- ated in Opium, — To the liquid or the semifluid mixture warmed for some time with a small quantity of acetic acid, filtered, and concentrated if necessary, add solution of acetate of lead until no further precipitate is produced. Filter and examine the precipitate for meconic acid, reserv- ing t\\Q filtrate for the detection of morphia. The Precipitate, — Wash the precipitate (meconate of lead, etc.) with water, place it in a test-tube or test-glass with a small quantity of water, pass hydrosulphuric acid gas through the mixture for a short time, filter, slightly warm in a small basin, well stirring to promote removal of excess of the gas, and add a drop of neutral solution of perchloride of iron ; a red color, due to the formation of meconate of iron, is produced if meconic acid is present. This color is not destroyed on boiling the liquid, as is the case with ferric acetate, nor is it bleached by solution of corrosive sublimate, thus distinguishing it from the ferric sulphocyanate. It is discharged by hydrochloric acid. The Filtrate, — The solution from which meconic acid has been removed by acetate of lead is evaporated to a small bulk over a water-bath, excess of carbonate of potas- sium added, and evaporation continued to dryness. Tlie residue is then treated with alcoiiol, which dissolves the CHEMICAL TOXICOLOGY. 425 morphia. The alcoholic solution evaporated similarly may leave the morphia sufficiently pure for the application of the usual tests {vide page 341) to small portions of the residue. If no reaction is obtained, add a drop of sul- phuric acid and a little water to the residue and shake with ether, in which the salt of morphia is insoluble. The treat- ment with ether may be repeated until nothing more is removed, the acid aqueous liquid saturated with carbonate of potassium, the mixture evaporated to drjmess, the resi- due digested in alcohol, filtered, and portions of the alco- holic liquid evaporated to obtain spots of morphia for the application of the ordinary tests. if much organic matter is believed to remain in the fil- trate after the acetate of lead treatment, or if a considerable excess of acetate of lead has been employed, the filtered liquid should be subjected to a current of sulphuretted h 3 alrogen until no more sulphide of lead is precipitated, the mixture filtered, and the filtrate, with the washings from the sulphide of lead, evaporated to a small bulk, excess of carbonate of potassium added, the whole well mixed and agitated with twice or thrice its bulk of a mixture of ether and acetic ether (ether alone might not dissolve the mor- phia). On standing the ethereal liquid rises to the surface ; it is carefully removed, evaporated to dryness, and the residue tested or further purified in the manner described in the preceding paragraph. The examination for morphia must be conducted with great care, and with as large a quantity of material as can be spared ; for its isolation from other organic matter is an operation of considerable difficulty, especially when only a minute proportion of alkaloid is present. Fortunately the detection of meconic acid does not include similar difficulties ; and, as its reactions are quite characteristic, its presence is held to be strong evidence of the existence of opium in an organic mixture. Examination for Other Poisonous Alkaloids* Stasis Process . — Minutely subdivide any solid matter; to this and the liquid portion of the vomit, etc., add about twice their weight of the strongest spirit of wine contain- ing sufficient tartaric acid to fairly acidify the mixture. Di- gest the whole in a fiask at a temperature of 150° or 160° F. ; set aside to cool; filter. The solution, which will contain the whole of the alkaloid, should then be evaporated nearly to dryness in vacuo., or at all events at a temperature not 36* 426 CHEMICAL TOXICOLOGY. exceeding 100° F., lest volatile alkaloids should be dissi- pated. The residue is next exhausted with cold anhydrous alcohol ; filtered ; and the filtrate evaporated to dryness with the precautions already stated. The extract is dis- solved in a very small quantity of water, treated with excess of powdered bicarbonate of sodium or potassium, and w’ell shaken with five or six times its volume of pure ether (with perhaps a little acetic ether). This ethereal liquid contains the alkaloid. Small portions should be evaporated in watch-glasses and tasted, or tested physically and chemi- cally, according as the knowledge of collateral circum- stances by the operator, or his experience, or the reactions recorded on pp. 349-354, may suggest. If a volatile alkaloid (conia, nicotia, hyosc^^amia, lobe- lina) is indicated, the ethereal solution, which may still contain animal matter, is removed, agitated with aqueous solution of potash, decanted, and shaken with pure diluted ! sulphuric acid. On standing, the aqueous portion, contain- | ing the alkaloid as acid sulphate, subsides ; the upper j ethereal portion containing the animal matter is rejected ; ! the acid aqueous liquid is made alkaline with caustic potash ! or soda; ether added; well shaken; the ethereal liquid j decanted, evaporated to dryness in vacuo ^ or at a low tern- I perature ; and (to get rid of all traces of ammonia) again | moistened with ether and dried. The residue is now tested j for the suspected alkaloid b 3 " taste, smell, and the applica- i tion of appropriate reagents (pp. 349-354). If a non-volatile alkaloid (aconitia, atropia, brucia, col- f chicia, emetia, physostigmia, solania, veratria, as well as morphia, codeia, and strychnia) is indicated, further purifi- cation is effected by decanting the ethereal liquid from the lower aqueous solution of bicarbonate of sodium, removing the ether by evaporation, digesting the residue in alcohol, filtering, evaporating the alcohol, treating the residue with dilute sulphuric acid, setting aside for a few hours, filtering, , concentrating, adding powdered carbonate of potassium, and finall 3 ^ anhydrous alcohol. The alcoholic liquid, on evaporation, ^fields the alkaloid in a fit state for testing in the manner alread}^ stated. Sonnenschien^s Process. — Digest with diluted hydro- chloric acid, evaporate to the consistence of s^’nip, dilute, set aside for some hours, filter. Add solution of phospho- mol 3 ^bdic acid so long as any precipitate falls or cloudiness occurs; collect the precipitate on a small filter; wash it with water containing phosphomolybdic and nitric acid, and, CHEMICAL TOXICOLOGY. 421 while still moist, place it in a flask. Decompose this com- pound of phosphomolybdic acid and alkaloid by adding caustic baryta until the stirred mixture is distinctly alka- line. Distil off volatile alkaloids, condensing and collect- ing by help of a long tube, so bent that the apparatus shall act as a retort, the end of the tube being attached to a bulb or a series of bulbs containing dilute hydrochloric acid. The acid liquid evaporated gives a residue of hydrochlorates of alkaloids. The latter will afford characteristic reactions with the tests for the suspected alkaloid, and, on being moistened with baiyta-water and warmed, will afford fumes of volatile alkaloids whose odor is usually characteristic. The residue in the flask will contain non-volatile alkaloids. It is treated with carbonic acid gas to neutralize and pre- cipitate the excess of baryta as insoluble carbonate of barium ; the mixture is evaporated to dryness over a water- bath ; and the residue digested in alcohol. The alcoholic solution evaporated generally yields the alkaloids in a fit state for testing. Phosphomolybdic acid forms with ammonia, in acid solutions, a remarkably insoluble compound, and it comports itself in a similar manner with those compounds which are analogous to ammonia — the nitrogenized organic bases — consequently forming an excellent re- agent for their detection. It may be prepared in the following manner : Molybdate of ammonium is precipitated by phosphate of sodium; the yellow precipitate, having been washed, is diffused through water, and heated with sufficient carbonate of sodium to dis- solve it. The solution is then evaporated to dryness, and calcined to drive off the ammonia. In case any of the molybdic compound be reduced by this operation, the residue must be moistened with nitric acid and again calcined. The dry mass is then dissolved in cold water, the solution strongly acidulated with nitric acid, and water added until ten parts of the solution contain one of the dry salt. The liquid, which is of a golden-yellow color, must be pre- served from ammoniacal fumes. It precipitates all the alkaloids (with the exception of urea) when a mere trace only is present. The precipitates are yellow, generally flocculent, insoluble in water, alcohol, ether, and the dilute mineral acids, with the exception of phosphoric acid. Nitric, acetic, and oxalic acids, concentrated and boiling, dissolve them. These compounds are decomposed by the alkalies, certain metallic oxides, and the alkaline salts, which sepa- rate the alkaloid. To give an idea of the sensibility of this reagent, it may be stated that the 0.000071 gramme of strychnia gives an ap- preciable precipitate with one cubic centimetre of the solution of phosphomolybdic acid. 428 CHEMICAL TOXICOLOGY. ANTIDOTES. Vide “Antidote” in the Index. QUESTIONS AND EXERCISES. 878. In examining food and similar matter for poison, why must not the ordinary tests for the poison be at once applied ? 879. What preliminary operations should be performed on a vomit in a case of suspected poisoning ? 880. How would you proceed in searching for corrosive sublimate in wine ? 881. By what series of operations ’would you satisfy yourself of the presence or absence of arsenic in the contents of a stomach ? 882. Describe the treatment to which decoction of coffee should be subjected in testing it for tartar-emetic. 883. State the method by which the occurrence of lead in water is demonstrated. 884. Give a process- for the detection of copper in jam. 885. How would you detect zinc in a vomit ? 88G. How may the presence o| a poisonous quantity of sulphuric acid in gin be proved ? 887. In examining ale for free nitric acid what reactions would be selected ? 888. Show how you would conclude that a dangerous quantity of hydrochloric acid had been added to cider. 889. Describe the manipulations necessary in testing for hydro- cyanic'4ci'd in the contents of a stomach. 890. By what method is oxalic acid discovered in infusion of coffee ? 891. How is the phosphorus detected in organic mixtures ? 892. Give the process by which strychnia is isolated from partially digested food. 893. Mention the experiments by which the presence of laudanum in porter is demonstrated. 894. Name the appropriate antidotes in cases of poisoning by : a, alkaloids; antimonials ; c, arsenic; d, barium salts; e, copper compounds; /, hydrochloric acid; g, hydrocyanic acid; /i, prepara- tions of lead ; i, corrosive sublimate ; nitric acid ; k, oxalic acid ; /, salts of silver ; m, oil of vitriol ; n, tin liquors ; o, zinc solutions ; p, carbolic a^id. MORBID URINE — ALBUMEN. 429 EXAMINATION OF MORBID URINE AND CALCULI. The various products of the natural and continuous decay of animal tissue and the refuse matter of food are eliminated from the system chiefly as faeces, urine, and expired air. Air exhaled from the lungs carries off from the blood much carbon (about 8 ounces in 24 hours), in the form of carbonic acid gas, and some aqueous vapor — the latter, together with a small amount of oily matter, also escaping by the skin. Directing the breath to a cold surface renders moisture evident ; and breathing through a tube into lime-water demonstrates the presence of a considerable quantity of carbonic acid gas. The faeces consist mainly of the insoluble debris of the system, the solu- ble matters and water forming the urine. These excretions vary con- siderably, according to the food and general habits of the individual and external temperature. But in disease the variations become excessive ; their detection by the medical practitioner, or by the pharmacist for the medical practitioner, is therefore a matter of im- portance. A complete analysis of faeces, urine, or expelled air cannot be per- formed in the present state of our knowledge. Nor can any analysis of faeces or air be made with sufficient ease and rapidity to be prac- tically available in medical diagnosis. But with regard to urine, certain abnormal substances and abnormal quantities of normal con- stituents may be chemically detected in the course of a few minutes by any one having already some knowledge of chemical manipulation. Healthy human urine contains, in 1000 parts, 957 of water, 14 of urea, 1 of uric acid, 15 of other organic matter, and 13 of inorganic salts. The acidity of urine Thudichum considers to be due to cryj)- tophanic acid, H2O5H7NO5. Examination of Morbid Urine for Albumen, Sugar, Bile, and Excess of Urea ; and Urinary Sediment FOR Urates (or Lithates), Phosphates, Oxalate of Calcium, and Uric Acid. Albumen — To detect albumen-, acidulate a portion of the clear urine in a test-tube with a few drops of acid (to keep phosphates in solution — nitric is best, acetic not so good) and boil; flocks or coagula will separate if albu nen be present. This experiment should first be made on normal urine c( ntaining a drop or two of solution of white of egg. A coagulum of pure albumen is white, greenish if bile pigment is present, and brownish- red if the urine contains blood. The influence of acids and alkalies on the precipitation of albumen is noticed on page 39G. 430 MORBID URINE The occurrence of albumen in the urine may be temporary and of but little importance ; or it may indicate the existence of a serious affection, known as Bright’s disease. Sugar . — To a portion of the clear urine in a test-tube add five or ten drops of solution of sulphate of copper ; pour in solution of potash or soda until the precipitate first formed is redissolved ; slowly heat the solution to near the boiling-point ; a yellow, yellowish-red, or red precipitate (cuprous oxide) is formed if sugar is present. This experiment should first be made on urine containing a drop or two of solution of grape-sugar (page 361). The hydrate of cop per precipitated by the alkali is insoluble in excess of pure potash or soda, but readily dissolves if organic matter, especially sugar, is present. The copper salt may not contain iron. Other tests may be applied if necessary (vide page 361). A minute amount of sugar is said to occur in normal urine and a disfinct trace is occasionally present. In larger quantities it is a characteristic constituent of the urine of diabetic patients, greatly increasing the specific gravity of the excretion. Small hydrometers (termed urinometers) are commonly employed for quickly and readily ascertaining the specific gravity of urine ; they range from 1000 to 1050, the interval of 1015 to 1025 being marked as “ H. S.,” or healthy state. (Vide “Specific Gravity’^f and “Hydrometers” in Index.) Bile . — This is best detected by the general test (Pettenkofer’s) described on pa^giiAfif • ^ little of the urine may be placed on a white plate an® sti^ong citric acid dropped on it ; a peculiar play of colors — green, yello^w, violet, etc. — occurs if (the coloring matter of) bile is present. Excels of Urea . — Nearly one-half of the solid matter in the urine is urea. Its proportion varies considerably; but per cent, may be regarded as an average amount. Con- centrate urine slightly by evaporation in a small dish, pour the liquid into the test-tube, set the tube aside till cold, or cool it by letting cold water run over the outside, add an equal bulk of strong nitric acid and again set aside; scaly crystals of nitrate of urea are deposited more or less quickly. With regard to the amount of urea in urine, it is impossible to sharply define excess or deficiency. If nitric acid gives crystals' without concentration, excess is certainly present. A rough estimate may be formed by mixing a few drops of the urine and acid on a piece of glass and setting aside ; the time which elapses before crys- tals form is an indication of the quantity in the specimen. The time will vary according to the temperature and state of moisture of the atmosphere; but with care some useful comparative results may iip this way be obtained. UREA. 431 Tests . — Urea in solution in water may be detected by the above reaction with nitric acid, and by the readiness with which it yields ammonia on being boiled with alkalies. In putrid urine its conver- sion into an ammoniacal salt has already been effected. CH.N^O + = (NHJ2CO3. Urea. Water. Garb, of ammon. Formula of Urea . — The empirical formula of urea is CH^N20. (CO)"] Its rational formula may be thus written: — H 2 VNg; that is, II J it may fie regarded as one of the organic bases already referred to, a primary diamine, in which the bivalent radical CO occupies the place of H 2 . The other atoms of hydrogen may be displaced by various radicals, and many compound ureas be thus obtained. Artificial Urea . — Urea may be prepared artificially by Williams’s modification of Wohler’s method. Cyanide of potassium, of the best commercial quality (containing about 90 per cent, of real cyanide), is fused at a very low red heat in a shallow iron vessel ; red lead is added in small quantities at a time, the temperature being kept down by constant stirring. When the red lead ceases to cause fur- ther action the mixture (cyanate of potassium and lead) is allowed to cool, the product finely powdered, exhausted with cold water, nitrate of barium added till no more precipitate (carbonate of ba- rium) falls, the mixture filtered, and the filtrate treated with nitrate of lead so long as cyanate of lead is thrown down. The latter is thoroughly washed, and dried at a low temperature. Equivalent quantities of cyanate of lead and sulphate of ammonium, digested in a small quantity of water at a gentle heat and filtered, yield a solu- tion from which urea crystallizes on cooling. Another Process . — Basaroff has found that urea is produced when ordinary carbonate ^ ammonium is heated in hermetically sealed tubes to aboul^fo^ F. for a few hours. The same chemist had pre- viously obtained urea by similarly heating pure carbamate of ammo- nium, so that fKe'source of the urea in the former case is probably the carbamate of ammonium believed to occur in the carbonate (see page 78). NH,NH2C02 ~ H 2 O = CH,N20. Urinary Sediments. Warm the sediment with the supernatant urine and filter. Insoluble. Soluble. Phosphates, oxalate of calcium, and uric acid. Warm with acetic acid, and filter. Urates — of ammoni- um, calcium, or so- dium, chiefly the latter. Insoluble. Oxalate of calcium and uric acid. Warm with hydrochloric acid, filter. Soluble. Phosphates. Add ammo- nia, white ppt. = phosphate of calcium, or They are redeposit- ed as the liquid cools, and if sufficient in quantity may be fur- ther examined for am- monium, calcium, so- dium, and the uric Insoluble. Uric acid. Apply mu- rexid test (p. 320). Soluble. Oxalate of cal- cium. May be re- precipitated by ammonia. ammonio-mag- nesium phos- phate, or both. radical by the appro- priate tests. Notes. — Urinary deposits are seldom of a complex character; the action of heat and acetic and hydrochloric acids generally at once indicates the character of the deposit, rendering filtration and pre- cipitation unnecessary. The urates are often of a pink or red color, owing ;to the presence of a pigment termed purpurme; hence the common name of red gravel for such deposits. Purpurine is soluble in alcohol, and may be removed by digesting a red deposit in that solvent. It is seldom necessary to determine whether the urate be that of ammonium, cal- cium, or sodium (see also Uric Acid, page 320). The phosphate of calcium and the ammonio-magnesium phos- phate are usually both present in a phosphatic deposit, the magne- sium salt forming the larger proportion. They may, if necessary, and if sufficient in quantity, be separated by collecting on a filter, w^ashing, and boiling with solution of carbonate of sodium. The carbonates of calcium and magnesium thus formed are collected on a filter, washed, dissolved in a drop or two of hydrochloric acid — chlo- ride of ammonium, ammonia, and carbonate of ammonium added, the mixture boiled and filtered ; any calcium originally present will then remain insoluble as carbonate of calcium, w'hile any magnesium will be reprecipitated from the filtrate as ammonio-magnesium phos- phate on the addition of phosphate of sodium, the mixture being also well stirred. The chief portion of excreted phosphates is car- ried off by the faeces, that remaining in the urine being kept in solu- URINARY SEDIMENTS. 433 tion by the influence of acid phosphate of sodium, and, frequently, lactic acid. -Occasionally, an hour or two after a hearty meal, the urine becomes sufficiently alkaline for the phosphates to be deposited, and the urine when passed is turbid from their presence. The am- moniacal constituent of the magnesium salt does not occur normally, but is produced from urea as soon as urine becomes alkaline. Oxalate of calcium is seldom met with in excessive amounts, but very often in small quantities mixed with phosphates. Free uric acid is in most cases distinctly crystalline, and nearly always of a yellow, red, or brown color. Artificial Sediments. — For educational practice, artificial deposits may be obtained as follows: 1. Eub up in a mortar a few^ grains of serpent’s excrement (chiefly urate of ammonium) with an ounce or two of urine ; this represents a sediment of urates. 2. Add a few drops of solution of chloride of calcium and of phosphate of sodium to urine ; the deposit may be regarded as one of phosphates. 3. To an ounce or two of urine add very small quantities of chloride of calcium and oxalate of ammonium ; the precipitate is oxalate of cal- cium. 4. To urine acidulated by hydrochloric acid add a little ser- pent’s excrement ; the sediment is uric acid. Other deposits than the foregoing are occasionally observed. Thus liippuric acid (HCgHgNO^), a normal constituent of human urine, and largely contained in the urine of herbivorous animals, is some- times found associated with uric acid in urinary sediment, especially in that of patients whose medicine contains benzoic acid (p. 301). Its appearance, as observed by the aid of the microscope, is characteristic — namely, slender, four-sided prisms, having pointed ends. Cystin (C3H7HSO2) (from xvguk;, kustis, a bladder, in allusion to its origin) rarely occurs as a deposit in urine. It is not soluble in warmed urine or dilute acetic acid, and scarcely in dilute hydrochloric acid, hence would be met with in testing for free uric acid. It is very soluble in ammonia, recrystallizing from a drop of the solution placed on a piece of glass in characteristic microscopic six-sided plates. Organ- ized sediments may be due to the corpuscles of pus, mucus, or blood, fat-globules, spermatozoa, cylindrical casts of the tubes of the kid- neys, epithelial cells from the walls of the bladder, or foreign matters, such as fibres of wool, cotton, small feathers, dust; these are best recognized by the microscope, as will be seen by the following para- graphs and figures on the microscopic appearances of both crystalline and organized urinary sediments. Microscopic Examination of Urinary Sediments. Urine containing insoluble matter is usually more or less opaque. For microscopical examination a few ounces should be set aside in a conical test-glass for an hour or two, the clear supernatent urine poured off from the sediment as far as possible, a small drop of the residue placed on a slip of glass and covered with a piece of thin glass and examined under the microscope with different magnifying- powers. SI ^ 434 MORBID URINE. The respective appearances of the various crystalline and organized matteVs are given in the following figures, which were drawn by mv friend K B. Brady, F.L.S., from natural specimens (as seen wfth a two-third inchob ective and No. 1 eye-piece, z. e., magnified 60 diaLters) in the collections of St. Bartholomew's Hospital, Dr. Sedgwick, W. W. Stoddart, F.C.S., Mr. M addington, and the Uric Acid occurs in many forms, most of which are given in the first two figures. Flat, more or less oval crystals, sometimes attached to each other, their outline then resembling an 8, a cross, or a star, are common. Single and grouped quadratic prising rJm urTe cula and crystals recalling dumb-bells are met with. From urine acidulated by hydrochloric acid, square crystals, two opposite sides smooth and two jagged, are generally deposited : acidulated by acetic smootnanuuvoj = acid more typical forms are ob- ) tained. A drop of solution of potash or soda placed on a glass slip will dissolve a deposit of uric acid, a drop of any acid re- precipitating it in minute but characteristic crystals. Cystin is very rarely met with as a urinary deposit ; that from which the figure was taken was found in the urine of a patient in St. Bartholomew’s Hospital. Lamellm of cystin always as- sume an hexagonal character ; but the angles are sometimes ill defined and the plates super- posed : in the latter case, a drop of solution of ammonia placed on the glass at once dissolves the deposit, well-marked six-sided crys- tals appearing as the drop dries up. URINARY SEDIMENTS. 435 Triple Phosphate (phosphate of magnesium and ammonium) is deposited as soon as urine becomes alkaline, the ammoniacal constitu- ent being furnished by the de- composition of urea. It occurs in large prismatic crystals, form- ing a beautiful object when viewed by polarized light — sometimes also in ragged stel- late or arborescent crystals, re- sembling those of snow. Both forms may be artificially pre- pared by adding a small lump of carbonate of ammonium to a few ounces of urine set aside in a test-glass. Amorphous deposits are either earthy phosphates (a mixture of phosphates of mag- nesium and calcium) or urates (of calcium, magnesium, ammo- nium, potassium, or sodium — chiefly the latter). They may be dis- tinguished by the action of a drop of acetic acid placed near the sediment on the glass slip, the effect being watched under the micro- scope ; phosphates dissolve, while urates gradually assume character- istic forms of uric acid. Urates redissolve when warmed with the supernatant urine. Urates of Sodium and Magnesium., though generally amorphous, occasionally take a crystalline form — bundles or tufts of small needles — as shown in the cut. Oxalate of UaZcmm commonly occurs in octahedra requiring high magnifying power for their detection. The crystals are easily over- looked if other matters are pre- sent, but are more distinctly seen after phosphates have been re- moved by acetic acid. In certain aspects the smaller crystals look like square plates traversed by a cross. A dumb-bell form of this deposit is also sometimes seen, resembling certain forms of uric acid and the coalescing spherules of a much rarer sedi- ment — carbonate of calcium. Oxalate of calcium is insoluble in acetic but soluble in hydro- chloric acid. The octahedra are frequently met with in the urine of persons who have partaken of garden rhubarb ; the crystals may often be deposited artificially (according to Waddington,) by dropping a fragment of oxalic acid into several ounces of urine and setting aside for several hours. Urates, a, of Sodium, b, of Magnesium. Oxalate of Calcium. 436 MORBID URINE. Carbonate of Calcium is rarely found in the urine of man, but frequently in that of the horse and other herbivorous animals. Human urine containing carbonate of calcium often reddens litmus paper; and it is only after the removal, on standing, of the excess of carbonic acid that the salt is deposited. It consists of minute sphe- rules, varying in size, the smaller ones often in process of coalescence. The dumb-bell form thus produced is easily distinguished from similar groups of uric acid or oxalate of calcium by showing a black cross in each spherule when viewed by polarized light. Acetic acid dis- solves carbonate of calcium, libe- rating carbonic acid gas, with visible effervescence (under the microscope) if the slide has been previously warmed and a group of crystals be attacked. Hippuric Acid . — The pointed rhombic prisms and acicular crys- tals are characteristic, and easily recognized. The broader crj'stals may possibly be mistaken for triple phosphate, and the nar- rower for certain forms of uric acid ; but insolubility in acetic acid distinguishes them from the former, and solubility in alcohol from the latter. These tests may be applied while the deposit is under microscopic observation. An alcoholic solution of hippuric acid evaporated to dryness, and the residue treated with water, gives a solution from which characteristic crystalline forms of hippuric acid may be obtained on allowing a drop to dry upon a slip of glass. The organized deposits in urine entail greater care in their determi- nation, and usually require a higher magnifying power for their proper examination, than those of crystalline form. The figures are drawn to 230 diameters. The following notes will assist the observer. Casts of uriniferous tubuli are fibrinous masses of various forms, and often of considerable length — sometimes delicate and transparent, occasionally granu- lar, and often beset with fat- globules. Epithelial debris are frequently present in urine in the form of nucleated cells, regu- lar and oval when full, but angu- lar and unsymmetrical when ])ar- tially emptied of their contents — sometimes perfect, but more frequently a good deal broken up. URINARY SEDIMENTS. 437 Blood is easily recognized. Urine containing it is high-colored, and the corpuscles appear under the microscope as reddish circular disks, either single or laid to- gether in strings resembling piles of coin. Their color and somewhat smaller size serve to distinguish them from pus-cor- puscles. In doubtful cases a drop of blood from the finger should be diluted with water and used for comparison. After urine containing blood has stood for some time, the corpuscles lose their regular outline and become angular. (See a in the figure.) Day, of Geelong, tests for blood in urine, or in stains on clothing, by adding a few drops of a recently prepared alcoholic solution of the inner unoxidized portions of guaiacum resin and then a small quantity of Robbins’s aqueous or ethereal solution of peroxide of hydrogen, when a blue color results. If the stain is on a dark-colored fabric, the moistened parts may be pressed with white blotting paper, when blue impressions will be obtained. Contact with many substances causes the blue reaction or oxidation of guaiacum ; the peculiarity of blood is that it does not produce this effect unless peroxide of hydro- gen or a similar antozonic liquid is present. Bodies such as per- manganate of potassium, whose oxygen is, apparently, in the form of ozone, also gives rise to a blue color with guaiacum ; peroxide of hydrogen and other compounds whose oxygen is in the opposite, positive, or, according to Schdnbein, antagonistic condition, produce no such effect. It would seem as if blood or some other constituent of blood has the power of converting positive into negative oxygen, and thus cause an effect which negative oxygen alone is able to pro- duce ; for of all substances which, like blood, do not alone cause guai- acum to become blue, blood is the only one that so affects antozo- nides (themselves inactive) as to enable them to act as ozonides, that is to oxidize the guaiacum. Both the venous and arterial fluid from any red-blooded animal will produce this blue reaction. Fruit stains are darkened by ammonia, which does not alter the color of blood. Iron stains or iron-mould yield no color to w^ater, whereas the red coloring-matter of blood is soluble in water. The peroxide of hydro- gen should be free from more than a trace of acid. Pus and Mucus . — Purulent urine deposits, on standing, a light- colored layer, easily diffused through the liquid by shaking. Acetic acid does not dissolve the sediment; and solution of potash, of official strength, converts it into a gelatinous mass. Under the micro- scope, pus-corpuscles appear rounded and colorless, rather larger than blood-disks, and somewhat granular on the surface. They generally show minute nuclei, which are more distinctly seen after 37 * 438 MORBID URINE. treatment with acetic acid. (See the portion of the figure marked a.) Mucus possesses no definite microscopic characters, but commonly has imbedded in it pus, epithe- lium, and air-bubbles. Mucus is coagulated in a peculiar and characteristic manner by acetic acid : and this reaction, together with the ropy appearance it imparts to urine, prevents its being confounded with pus. Day’s test for pus consists in adding a drop or two of oxidized tincture of guaiacum, to the urine or other liquid, when a clear blue color is produced. It is necessary to moisten dry pus with water before apply- ing the test. The test liquid is made by exposing a saturated alcoholic solution of guaiacum to the air until it has absorbed a sufficient quantity of oxygen to give it the property of turning green when placed in contact with iodide of potassium. Day’s test for mucus consists in the application, first, of oxidized tincture of guaiacum, which by itself undergoes no change in the presence of mucus, and then in the addition of carbolic acid or creasote, which quickly changes the color of the guaiacum to a bright blue. Neither carbolic acid nor creasote alone will render guaiacum blue. In testing for mucus on cloths, or when it is mixed with blood, it is necessary to use the carbolic acid pure, but when the mucus is in a liquid state it is better to use carbolic acid diluted with alcohol. Saliva . — Saliva is an aqueous fluid containing less than I per cent, of solid matter, of which one- third is an albuminoid substance, termed pt^alm (from rttvsKov, spittle), a body that has power of con- verting starch into dextrin and grape-sugar. Alkaline salts, in- cluding a trace of sulphocyanide of potassium, and calcareous compounds, are also present. Day’s test for saliva in urine, etc., is similar to that for mucus, with the exception that the bine reaction produced by the oxi- dized tincture of guaiacum and alcoholic solution of carbolic acid is highly intensified by the addition of Eobbins’s aqueous or ethereal solution of peroxide of hydrogen. Fatty matter occurs either as minute globules partially dif- URINARY CALCULI. 439 fused through the urine (as shown at a) or in more intimate emulsion (as at h in the figure). When present in larger quantity, it collects as a sort of skim on the surface after standing. Spermatozoa are liable to escape notice, on account of their small size and extreme transparency. Suspected urine should be allowed to settle some hours in a conical test-glass, and the drop at the bot- tom examined under a high power. The drawing shows their tad- pole-like appearance. Sarcina ventriculi is an alga of very rare occurrence in urine, though not unfrequent in the matters vomited during certain diseases of the stomach. The upper figures (a) are copied from Dr. Thudi- chum’s drawing (from urine) ; the larger fronds (&) are from vomited matter. Extraneous bodies, such as hair, wool, or fragments of feathers, are often found in urinary deposits ; and ludicrous mistakes have been made by observers not on their guard in respect to such casual admixtures. Examination of Ueinary Calculi. The term calculus is the diminutive of calx, a lime- or chalk-stone. Knowledge of the composition of a calculus or urinary deposit affords valuable diagnostic aid to the physician ; hence the import- ance of a correct analysis of these substances. Nature of Calculi. — Urinary calculi have the same composition as unorganized urinary sediments. They consist, in short, of sedi- ments that have been deposited slowly within the bladder, particle on particle, layer on layer, the several substances becoming so com- pact as to be less easily acted on by reagents than when deposited after the urine has been passed — the urates less readily soluble in warm water, the calcic phosphate insoluble in acetic acid until it has been dissolved in hydrochloric acid and reprecipitated by an alkali. Preliminary Treatment. — If the calculus is whole, saw it in two through the centre, and notice whether it is built up of distinct layers or apparently consists of one substance. If the latter, use about a grain of the sawdust for the analysis ; if the former, carefully 440 MORBID URINE. scrape off portions of each layer, and examine them separately. If the calculus is in fragments, select fair specimens of about half a grain or a grain each, and reduce to a fine powder by placing on a hard surface and crushing under the blade of a knife. Analysis , — Comnaence the analysis by* heating a portion about the size of a pin’s head, on platinum foil, in order to ascertain whether organic matter, inorganic matter, or both, are present. If both, the ash is examined for inorganic sub- stances, and a fresh portion of the calculus for uric acid by the murexid test. (In the absence of uric acid an}" slight charring may be considered to be due to indefinite animal matter.) If composed of organic matter only, the calculus will in nearly all cases be uric acid, the indication being confirmed by applying the murexid test in a watch- glass to another fragment, half the size of a small pin’s head. If organic only, the ash on the platinum foil may be examined for phosphates, and a separate portion of the calculus for oxalates. Even a single drop of liquid ob- tained in any of these experiments maybe filtered by placing it on a filter not larger than a sixpence and previously moist- ened with water, and adding three or four drops of water one after the other as each passes through the paper. If the calculus is suspected to contain more than one sub- stance, boil about half a grain of the powder in half a test- tubeful of distilled water for a few minutes and pour it on a small filter; then proceed according to the following Table Insoluble. Phosphates, oxalates of calcium, and free uric acid. Boil with two or three drops of hydrochloric acid and filter. Soluble. Urates. These will pro- , bably be redepos- ited as the solu- tion cools. Small Insoluble. Uric acid. Apply the murexid test (p. 320). Soluble. Phosphates and oxalate of calcium. Add excess of ammonia, and then excess of acetic acid ; filter. quantities may be detected by eva- porating the solu- tion to dryness. They are tested for ammonium, so- dium, calcium, and Insoluble. Soluble. the uric radical by the appropriate re- Oxalate of Phosphates. agents. calcium. They may be repre- cipitated by ammonia. / QUESTIONS AND EXERCISES. 441 Varieties of Calculi. — Calculi composed entirely of uric acid are common ; a minute portion heated on platinum foil chars, burns, and leaves scarcely a trace of ash. The phosphates frequently occur together, forming what is known as the fusible calculus, from the readiness with which a fragment aggregates, and even fuses to a bead, when heated on a loop of platinum wire in the blowpipe-flame. The phosphates may, if necessary, be further examined by the method described in connection with urinary deposits. Oxalate of calcium often occurs alone, forming a dark-colored calculus having a very rough surface, hence termed the mulberry calculus. Smaller calculi of the same substance are called, from their appearance, hempseed calculi. Calculi of cystin are rarely met with. Xaviliin (from xanthos, yellow, in allusion to the color it yields with nitric acid) still less often occurs as a calculus. The earthy concretions, or chalk-stones, which frequently form in the joints of gouty persons, are composed chiefly of urates, the sodium salt being that most com- monly met with. Gall-stones or biliary calcidi, occasionally form in the gall-bladder: they contain cholesterin (from chole, bile, and (jrfpfoj, stereos, solid), a fatty substance of alcoholoid constitution, soluble in rectifled spirit or ether, and crystallizing from such solu- tions in well-defined, square, scaly crystals. Phosphatic and other calculi of many pounds weight are often found in the stomach and larger intestines of animals. QUESTIONS AND EXERCISES. 895. In breathing, how much carbon (in the form of carbonic acid gas) is exhaled from the lungs every 24 hours ? 896. How may the presence of carbonic acid gas in expired air be demonstrated ? 897. Mention an experiment showing the escape of moisture from the lungs during breathing. 898. State the method of testing for albumen in urine. 899. Give the tests for sugar in urine. 900. What is the average composition of healthy urine ? 901. Give the tests for urea. 902. Write the rational formulae of some compound ureas in which methyl or ethyl displace hydrogen. 903. Describe an artificial process for the production of urea, giving equations. 904. Sketch out a plan for the chemical examination of urinary sediments. 905. A deposit is insoluble in the supernatant urine or in acetic acid ; of what substances may it consist ? . 906. Which compounds are indicated when a deposit redissolves on warming it with the supernatant urine ? 907. Name the salts insoluble in warmed urine but dissolved on the addition of acetic acid. 442 OFFICINAL GALENICAL PREPARATIONS. 908. Mention the chemical characters of cystin. At what stage of analysis would it be recognized? 909. Describe the microscopical appearance of the following urin- ary deposits : — ^ Uric Acid. Cystin. Triple phosphate. Earthy phosphates. Urates. Oxalate of Calcium. Carbonate of Calcium. Hippuric Acid. Tube-casts. Epithelial debris. Blood. Pus. Mucus. Fat. Spermatozoa. Sarcina. Extraneous Bodies. 910. How are Day’s tests for blood, pus, and saliva applied ? 911. What is the general, physical, and chemical nature of urinary calculi ? 912. How are urinary calculi prepared for chemical examination ? 913. Draw out a chart for the chemical examination of urinary calculi. 914. Why is the fusible calculus” so called, and what is its com- position ? 915. State the characters of “ mulberry” and “ hempseed” calculi. 916. What are the “ chalk-stones” of gout and “ gall-stones” or biliary calculi ?” THE GALENICAL PREPARATIONS OF THE BRITISH PHARMACOPCEIA. The preparation of Confections, Decoctions, Enemas, j Extracts, Glycerines, Infusions, Inhalations, Juices, Lini- [ ments. Lozenges, Mixtures, Ointments, Pills, Plasters, i Poultices, Powders, Spirits, Suppositories, Syrups, Tine- | tures, and Wines, includes a number of mechanical rather | than chemical operations, and belongs to the domain of | pure Pharmacy. The medical or pharmaceutical pupil will ! have had ample opportunity of practicall}^ studying these i compounds before working at experimental chemistry, and , will^pr^ably have prepared many of them according to tlre'^directions of the Pharmacopoeia; if not, he is referred : to the pages of the last edition of that work for details. i Among the extracts of the British Pharmacopoeia, how- | ever, there are five (namely, those of Aconite, Belladonna, Hemlock, Henbane, and Lettuce) which are not simply i evaporated infusions, decoctions, or tinctures, like most : OFFICINAL GALENICAL PREPARATIONS. 443 others, but are evaporated juices from which vegetable albumen, the supposed source of fermentation and decay, has been removed, and chlorophyll (the green coloring- matter of plant-juice) retained practically unimpaired in tint. In order that attention may be concentrated on the process by which these are prepared, rather than on the extracts themselves, it is advisable to make an extract of some ordinary green vegetable, such as cabbage or turnip- tops. Bruise the green leaves of a good-sized cabbage in a mortar, and press out the juice; heat it gradually to 130°, and remove the green flocks of chlorophyll which separate, by filtration through calico. When the liquor has all passed through the filter, set the chlorophyll aside for a time, heat the strained liquor to 200° to coagulate albumen ; remove the latter by filtration and throw away ; evaporate the filtrate by a water-bath to the consistence of thin syrup ; then add to it the chlorophyll, and, stirring the whole together assiduously, continue the evaporation at a temperature not exceeding 140°, until the extract is of a suitable consistence for forming pills. A higher tem- perature than that indicated would cause the alteration of the chlorophyll to a dark-brown substance, the extraet no longer having the green tint which custom and the British Pharmacopoeia demand. QUESTIONS AND EXEKCISES. 917. Enumerate the different classes of official galenical prepara- tions. 918. Describe the general process for the preparation of green extracts : — Aconite. Hemlock. Belladonna. Henbane. Lettuce. 919. Why is vegetable albumen excluded in the preparation of green extracts ? 920. How may chlorophyll be removed from vegetable Mces^;attd again be introduced into their evaporated residues, withouvde^tro^^ ing its color. 921. For what reason is exposure of chlorophyll to heat avoided in the manufacture of green extracts ? 444 OFFICINAL CHEMICAL PREPARATIONS. THE CHEMICAL PREPARATIONS OF THE PHARMACOPCEIAS. The process by which every official chemical substance is prepared has already been described, and the strict chemical character of the processes illustrated by experi- ments and explained by aid of equations. Should the reader, in addition, desire an intimate acquaintance with those details of manipulation on which the successful and economic manufacture of chemical substances depends, he is advised to prepare, if he has not done so already, a few ounces of each of the salts mentioned in the Pharmacopoeias or commonly used in Pharmacy. An additional guide in these operations will be the Pharmacopoeia itself. The production of many chemical and galenical sub- stances on a commerical scale can only be successfully car- ried on in manufacturing-laboratories and with some knowl- edge of the circumstances of supply and demand, value of raw material, and of by-products. Commercial Chem- istry and Pharmacy, however, can best hope for success when founded on the working out of abstract principles. The problem of manufacturing-success is solved with cer- tainty by wisely applied science. Memorandum , — The next subjects of experimental study will be determined by the nature of the student’s future pursuits. In most cases the operations of quantitative analysis will engage attention. These should be of a volu- metric and gravimetric character ; for details concerning them see the following pages. QUANTITATIVE ANALYSIS. 445 QUANTITATIVE ANALYSIS. INTEODUCTORY REMARKS. General Principles . — The proportions in which chemical substances unite with each other in forming compounds are definite and invari- able (p. 41). Quantitative analysis is based on this law. When, for example, aqueous solutions of a salt of silver and a chloride are mixed, a white curdy precipitate is produced containing chlorine and silver in atomic proportions, that is, 35.5 parts of chlorine to 108 of silver. No matter what the chloride or what the salt of silver, the resulting chloride of silver is invariable in composition. The formula AgOi is a convenient picture of this compound in these proportions. The weight of a definite compound being given, therefore, the pro- portional amounts of its constituents can be ascertained by simple calculation. Thus, for instance, 8.53 parts of chloride of silver con- tain 2.11 parts of chlorine and 6.42 of silver : for if 143.5 (the molec- ular weight) of chloride of silver contain 35.5 (the atomic weight) of chlorine, 8.53 of chloride of silver will be found to contain 2.11 of chlorine : — 143.5 : 35.5 : : 8.53 : ic 8.53 1.065 17.75 284.0 143.5)302.815(2.11 287.0 15.81 14.35 1.465 1.435 x = 2.ll. And if 143.5 of chloride of silver contain 108 of silver, 8.53 of chlo- ride of silver will contain 6.42 of silver. To ascertain, for example, the amount of silver in a substance, containing, say, nitrate of silver, all that is necessary is to take a weighed quantity of the substance, dissolve it, precipitate the whole of the silver by adding hydrochloric acid or other chloride till no more chloride of silver falls, collect the precipitate on a filter, wash, dry, and weigh. The amount of silver in the dried chloride, ascertained by calculation, is the amount of silver in the quantity of substance on which the operation was con- ducted ; a rule-of-three sum gives the quantity per cent. — the form in which the results of quantitative analysis are usually staled. 38 446 QUANTITATIVE ANALYSIS. Occasionally a constituent of a substance admits of being isolated and weighed in the uncombined state. Thus the amount of mercury in a substance may be determined by separating and weighing the mercury in the metallic condition ; if occurring as calomel (HgCl) or corrosive sublimate (HgCl.^), the proportion of chlorine may then be ascertained by calculation (Hg = 200; Cl = 35.5). Nature of Gravimetric Quantitative Analysis. — As above stated, a body may be isolated and iveighed and its quantity thus ascertained ; or it may be separated and weighed in combination with another body whose combining proportion is well known ; this is quantitative analysis by the gravimetric method. Nature of Volumetric Quantitative Analysis. — Quantitative an- alysis by the volumetric method consists in noting the volume of a liquid required to be added to the substance under examination before a given effect is produced. Thus, for instance, a solution of nitrate of silver of known strength may be used in experimentally ascertain- ing an unknown amount of chlorine in any substance. The silver solution is added to a solution of a definite quantity of the substance until flocks of chloride of silver cease to be precipitated : every 108 | parts of silver added (or 170 of nitrate of silver: Ag=108, N=14 03=48 ; total 170) indicates the presence of 35.5 of chlorine, or an equivalent quantity of any chloride. The preparation of standard solutions, such as that of nitrate of silver, to which allusion is here \ made, requires considerable care ; but when made, certain analyses | can be executed with far more rapidity and ease than by gravimetric | processes. ; Note. — The quantitative analysis of solids and liquids often in- i volves determinations of temperature and specific gravity. These i processes will now be explained, after which an outline of volumetric | and gravimetric quantitative analysis will be given. The scope of : this work precludes any attempt to describe all the little mechanical ! details observed by quantitative analysts ; essential operations, how- 1 ever, are so fully treated that expert manipulators will meet with i little difficulty. I Measurement of Atmospheric Pressure. I The Barometer. — The analysis of gases and vapors involves, also, determinations of the varying pressure of the atmosphere as indi- ! cated by the barometer (from jSapoj, bar os, weight, and me- > tron, measure). The ordinary mercurial barometer is a glass tube 33 or 34 inches long, closed at one end, filled with mercury, and in- verted in a small cistern or cup of mercury. The mercury remains in the tube owing to the weight or pressure of the atmosphere on the i exposed surface of the liquid, the average height of the column being nearly 30 inches. In the popular form of the instrument, the i wheel-barometer, the cistern is formed by a recurvature of the tube ; \ on the exposed surface of the mercury a float is placed, from which ; • a thread passes over a pulley and moves an index whenever the i column of mercury ilses or falls. As supplied to the public these i barometers are usually inclosed in ornamental frames with thermo- ; MEASUREMENT OF TEMPERATURE. U1 meters attached. In the wheel-barometer the glass tube and con- tained column of mercury are altogether inclosed, the index alone being visible. In the other variety the upper end of the glass tube and mercurial column are exposed and the height of the mercury is ascertained by direct observation. The aneroid barometer (from a, a, ivithout, and neros, fluid) consists of a small, shallow, vacuous metal-drum, the sides of which approach each other when an increase of atmospheric pressure occurs, their elasticity enabling them to recede toward their former position on a decrease of pressure. This motion is so multiplied and altered in direction by levers, etc., as to act on a hand traversing a plate on which is marked numbers corresponding with those showing the height of the mercurial column of the ordinary barometer by which the aneroid was adjusted. The Bourdon barometer (from the name of the inventor) is a modified aneroid, containing, in the place of the round metal box, a flattened vacuous tube of metal, bent nearly to a circle. These barometers are also useful for measuring the pres- sure in steam-boilers, etc. Under the name of 'pressure-gauges they are sold to indicate pressures of 500 pounds and upwards per square inch. From their portability (they can be made of 1 to 2 inches in diameter and I inch thick) they are excellent companions for trav- ellers wishing to know the heights of hills, mountains, and other elevations. For further information concerning the influence of pressure on the volume of a gas or vapor see page 469 ; and for descriptions of the methods of analyzing gases, refer to Ganot^s Physics” (trans- lated by Atkinson), Miller’s “Chemical Physics,” and “Analysis of Gases” in Watts’s “ Dictionary of Chemistry.” MEASUREMENT OF TEMPERATURE. General Principles . — As a rule, all bodies expand on the addi- tion, and contract on the abstraction of heat, the alteration in volume being constant and regular for equal increments or decre- ments of temperature. The extent of this alteration in a given sub- stance, expressed in parts or degrees, constitutes the usual method of intelligibly stating, with accuracy, precision, and minuteness, a particular condition of warmth or temperature, that is, of sensible heat. The substance commonly employed for this purpose is mer- cury, the chief advantages of which are that it will bear a high tem- perature without boiling, a low temperature without freezing, does not adhere to glass to a sufficient extent to “ wet” the sides of any tube in which it may be inclosed, and, from its good conducting- power for heat, responds rapidly to changes of ^temperature. Plati- num, earthenware, alcohol, and air are also occasionally used for thermometric purposes. The Thermometer . — The construction of an accurate thermometer is a matter of great difficulty ; but the follow- ing are the leading steps in the operation. Select a piece 448 QUANTITATIVE ANALYSIS. of glass tubing having a fine capillary (capillus^ a hair) bore, and about a foot long.; heat one extremity in the blowjiip e-flame until the orifice closes, and the glass is sufii- cientl}^ soft to admit of a bulb being blown ; heat the bulb to expel air, immediately plunging the open extremity of the tube into mercury ; the bulb having cooled, and some mercury having entered and taken the place of expelled air, again heat the bulb and tube until the mercury boils and its vapor escapes through the bore of the tube ; again plunge the extremity under mercury, which will probably now completely fill the bulb and tube. When cold the bulb is placed in melting ice. The top of the column of mercury in the capillary tube should then be within an inch or two of the bulb ; if higher, some of the mercury must be expelled by heat ; if lower, more metal must be intro- duced as before. The tube is now heated near the open end and a portion drawn out, until the diameter is reduced to about one-tenth. The bulb is next warmed until the mer- curial column rises above the constricted part of the tube^ which is then rapidly fused in the blowpipe-flame, and the extremity of the tube removed. The instrument is now ready for graduation. The bulb is placed in boiling-water (a medium having, caeteris paid- bu8^ an invariable temperature), and, when the position of the top of the mercurial column is constant, a mark is made on the tube by a scratching diamond or a file. This operation is repeated with melting ice (also a medium having an invariable temperature). The space between these two marks is divided into a certain number of inter- vals termed degrees. Unfortunately this number is not uniform in all countries : in England it is 180, as proposed by Fahrenheit; in France 100, as proposed by Celsius (the Centigrade scale), a number generally adopted by sci- entific men ; in some parts of the Continent the divisions ai*e 80 for the same interval, as suggested by Ecaumur. Whichever be the number selected, similar markings should be continued beyond tlie boiling- and freezing-points as far as the length of the stem admits. Thermometric Scales . — On tlie Centigrade and Iteaumur scales the freezing point of water is made zero, and the boiling point 100 and 80 respectively ; on the Fahrenheit scale the zero is placed 32 degrees below the congealing-point of water, the boiling-point of which becomes, consequently, 212. Even on the Fahrenheit system temperatures below the freezing-point of water are often spoken of as “ degrees of frost ;” thus 1 0 degrees as marked on the thermom- THERMO METRIC SCALES. 449 eter would be regarded as “ 13 degrees of frost.’* It is to be regret- ted that the freezing-point of water is not universally regarded as the zero-point, and the number of intervals between that and the boiling-point everywhere the same. The degrees of one scale are easily converted into those of another, if their relations be remembered, namely: 180 (F.), 100 (C.), 80 (R.) ; or 18, 10, and 8 ; or, best, 9, 5, and 4. Formulae for the conversion of degrees of one thermometric scale into those of another, F=Fahrenheit. C—Centigrade. R=Reaumur. D=The observed degree. If above the freezing-point of water (32^ F ; 0^ C ; 0^ R), FintoC (D— 32)-4-9 x5. F “ R 32)-^9x4. C F R-t- 5 X 94-32. R “ F D-4- 4 X94-32. If below freezing, but above 0^ F ( — 17^.77 C; — 14^.22 R), F into 0 — (32 — D)-^9x5. F “ R -_(32— D)-^9x4. 0 ‘‘ F 32— (D~.5x9). R F 32— (D-~4x9). If below OO F (—170.77 C ; —140.22 R). F into 0 _(D-t-32)-^9 x5. F “ R _(D-l-32)-f-9 X4. C “ F ._(D-^ 5 x9)— 32. R F -_(D-i- 4 x9)— 22. For all degrees : — C into R D-f-5x4. R C D-4-4X5. In ascertaining the temperature of a liquid,^ the bulb of a thermometer is simply inserted and the degree noted. In determining the boiling-point, also, the bulb is inserted ill the liquid, if a pure substance. In taking the boiling- point of a. liquid which is being distilled from a mixture, the bulb of the thermometer should be near to but not beneath the surface. The following are the boiling points of a few substances met with in pharmacy : — Centigrade. Fahrenheit. Alcohol, absolute 78.3 173 “ 84 per cent 79.5 175 “ 49 per cent, (proof spirit) . . 81.4 178.5 amylic 132.2 270 Benzol 80.6 177 Bromine 63.0 145.4 Benzoic acid 239.0 462 ( -arbolic acid 187.8 370 38 * 450 QUANTITATIVE ANALYSIS. Centigrade. Fahrenheit. C 111 or 0 form 61 142 Ether (B. P.) (below) 40.5 105 “ pure 35 95 Mercury in vacuo (as in a thermometer) 304 580 “ in air (barom. at 30 inches) . . 350 662 Water (barom. at 29.92 inches) . . . 100 212 “ ( “ 29.33 “ ) ... 99.5 211 ‘‘ ( “ 28.74 “ ) . . . 99 210 Saturated solutions of — Cream of tartar 101 214 Common salt 106.6 224 Sal ammoniac 113.3 236 Nitrate of sodium 119 246 Acetate of sodium 124.4 256 Chloride of calcium 179.4 355 By ‘‘ gentle heat,” U. S. P., is meant any temperature between 900 and lOOO F. To Determine Melting-points of Fat, — Heat a fragment of the substance (spermaceti or wax for example) till it liquefies, and then draw up a small portion into a thin glass tube, about the size of a knitting-needle. Immerse the tube in cold water contained in a beaker, and slowly heat the vessel till the thin opaque cylinder of solid fat melts and becomes transparent : a delicate thermometer placed in the water indicates the point of change to the fifth of a degree. Remove the source of heat, and note | the congealing-point of the substance ; it will be identical | with or close to the melting-point. f Pyrometers, — Temperatures above the boiling-point of » mercuiy are determined by ascertaining to what extent a bar of platinum or porcelain has elongated. The bar is f inclosed in a cavity of a suitable case, a plug of platinum ii or porcelain placed at one end of the bar, and the whole exposed in the region whose temperature is to be found. After cooling, the distance to which the bar has forced the , plug along the cavity is accurately measured and the cor- ;! responding degree of temperature noted. The value of the distanc e is fixed for low temperatures by comparison with a mercurial thermometer, and the scale carried up- : wards through intervals of equivalent length. Such ther- .v mometers are conventionally distinguished from ordinary j instruments by the name pyrometer (from rtvp, piir,^ fire, Ji and ^trpoj/, metron^ measure). ! The following mellwg-j^oints of olTicial substances are |- given in the British Pharmacopnpia : — • i QUESTIONS AND EXERCISES. 451 In degrees Tn degrees Centigrade. Fahrenheit. Acetic acid, glacial 8.9 48 a a congeals at I.I 34 Benzoic acid . . 120 248 Carbolic acid . . 35 95 Oil of theobroma . 50 122 Phosphorus . . 43.3 no Prepared lard . . . (about) 38 100 “ suet . . 39.5 103 Spermaceti . . 38 100 White wax . . (not under) 65.5 150 Yellow wax . . 60 140 The order of fusibility of a few of the metals is as fol- lows : — Mercury . . . . , In degrees Centigrade. In degrees Fahrenheit. ~ 39 Potassium . . . . . . . 4- 62.5 + 144.5 Sodium . . . . , . . . . 97.6 207.7 Tin . . . . 227.8 442 Bismuth . . . . 264 507 Lead . . . . 325 617 Zinc . . . . 411.6 773 Antimony ... . . . . G21 1150 Silver . . . . , . . . . 1023 1873 Copper . . . . , . . . . 1091 1996 Gold .....' . . . . 1102 2016 Cast iron . . . . . . . 1530 2786 QUESTIONS AND EXERCISES. 922. On what fundamental laws are the operations of quantitative analysis based ? 923. What is the general nature of gravimetric quantitative analysis ? 924. Describe the general principle of volumetric quantitative analysis. 925. flow are variations in atmospheric pressure quantitatively determined ? 926. Explain the construction and mode of action of a mercurial barometer. 927. In what respect does a wheel-barometer differ from an instru- ment in which the readings are taken from the top of the column of mercury ? 928. Describe the principle of action of an aneroid barometer. 929. On what general principles are thermometers constructed ? 930. What material is employed in making thermometers ? 452 QUANTITATIVE ANALYSIS. 931. AYhy is mercury selected as a thermometric indicator ? 232. Describe the manufacture of a mercurial thermometer. 933. How are thermometers graduated ? 934. Give formulae for the conversion of the degrees of one ther- mometric scale into those of another, [a) when the temperature is above the freezing-point of water, (5) below 32^ F. but above 0° F., and (c) below 0° F. 935. Name the degree C. equivalent to 60^ F. 936. What degree C. is represented by — 4^ F. ? 937. Mention the degree F. indicated by 20^ C. 938. Convert 100^ R. into degrees C. and F. 939. State the boiling-points of alcohol, chloroform, ether, mer- cury, and water on either thermometric scale. 940. Describe the details of manipulation in estimating the melt- ing-point of fats. 941. In what respect do pyrometers differ from thermometers ? 942. Mention the melting-points of glacial acetic acid, oil of theo- broma, lard, suet, and wax. 943. Give the fusing-pomts of tin, lead, zinc, copper, and cast-iron. ESTIMATION OF WEIGHT. DEFINITIONS. All bodies, celestial and terrestrial, attract each other, the amount of attraction being in direct proportion to the quantity of matter of which they consist, and in inverse proportion to the squares of their distances. This is gravitation. When gravitation in certain direc- tions is exactly counterbalanced by gravitation in opposite directions, a body (e. g. the earth) remains suspended in space. Such a body, in relation to other bodies, has gravity but not weight. Weight is the effect of gravity, being the excess of gravitation in one direction over and above that exerted in the opposite direction. Weight, truly, in any terrestrial substance, is the excess of attraction which it and the earth have for each other over and above the attraction of each in opposite directions by the various heavenly bodies. But. practically, the weight of any terrestrial substance is the effect of the attraction of the earth only. Specific weight is the definite or precise weight of a body in relation to its bulk ; it is more usually but not quite correctly termed specific gravity — gravity belonging to the earth, not to the substance. QUESTIONS. 944. What is understood by gravitation ? 945. State the difference between weight and gravity. 946. Mention a case in which a body has gravity but no apparent w^eight. 947. Practically, what causes the weight of terrestrial substances ? WEIGHTS AND MEASURES. 453 Weights and Measures. The Balance . — The balance used in the quantitative operations of analytical chemistry must be accurate and sensitive. The points of suspension of the beam and pans should be polished steel or agate knife-edges, working on agate planes. It should turn easily and quickly, without too much oscillation, to or of a grain, or of a milligramme, when 1000 grains, or 50 or 60 grammes, are placed in each scale. (Grammes are weights of the metric system, a description of which is given on the next two or three pages.) The beam should be light and strong, capable of supporting a load of 1500 grains or 100 grammes ; its oscillations are observed by help of a long index attached to its centre, and continued downward for some distance in front of the supporting pillar of the balance. The instrument should be provided with screws for purposes of adjust- ment, a mechanical contrivance for supporting the beam above its bearing when not in use or during the removal or addition of weights, spirit levels to enable the operator to give it a horizontal position, and be inclosed in a glass case to protect from dust. It should be placed in a room the atmosphere of which is not liable to be con- taminated by acid fumes, in a situation free from vibration ; and a vessel containing lumps of quicklime should be placed in the case to keep the inclosed air dry and prevent the formation of rust on the steel knife-edges or other parts. During weighing, the doors of the balance should be shut, in order that currents of air may not un- equally influence the pans. The Weights . — These should be preserved in a box having a sepa- rate compartment for each. They must not be lifted directly with the Angers, but by a small pair of forceps. If grain-weights, they should range from 1000 grs. to gr., a weight being fashioned of gold wire to act as a ‘‘ rider” on the divided beam, and thus indicate by its position lOOths and lOOOths of a grain. From to 10 grs. the weights may be of platinum ; thence upward to 1000 grs. of brass. The relation of the weights to each other should be decimal. Metric decimal weights may range from 100 grammes to 1 gramme, of brass, and thence downward to 1 centigramme, of platinum, a gold centigramme rider being employed to indicate milligrammes and tenths of a milligramme. Weights and Measures of the TJ. S. Pharmacopoeia— The weights and measures used by physicians and apothecaries in the United States, when prescribing and preparing medicines, are the following — as stated in the U. S. Pharmacopoeia. Wei^its . — These are derived from the troy 'pound, and are exhi- bited in the following table, with their signs annexed : — One pound, K = 12 One ounce, § = 8 One drachm, ^ = 3 One scruple, 9 . . One grain gr. . . ounces = 5760 grains, drachms = 480 grains, scruples = 60 grains. . . . = 20 grains. . . . = 1 grain. In order to avoid the danger of mistakes from confounding the troy and avoirdupois pounds, the term pound is disused in the for- 454 QUANTITATIVE ANALYSIS. TTiiilae of the U. S. Pharmacopoeia, and the desired weight is expressed in ounces, each containing four hundred and eighty grains. This ounce is always printed troyounce, to guard against the error of sub- stituting for it the avoirdupois ounce, consisting of four hundred and thirty-seven and a half grains. The drachm and scruple are also disused, and replaced by their equivalents in grains. It is highly important that persons engaged in preparing medi- cines should be provided with troy weights. But those who are not so provided can make their avoirdupois weights available as substi- tutes for troy weights, by bearing in mind that 42.5 grains, added to the avoirdupois ounce, will make it equal to the troy ounce ; and that 1240 grains, deducted from the avoirdupois pound, will reduce it to the troy pound. Measures . — These are derived from the wine gallon, and are given in the following table, with their signs annexed : — One gallon, 0 = 8 pints = 61,440 minims. One pint, 0 = 16 fluidounces = 7,680 minims. One fluidounce, fg = 8 fluidrachms = 480 minims. One fluidrachm, f^ = 60 minims. One minim, tt^ = 1 minim. In this work the term gallon is not used, that measure being j always expressed in pints. i At the temperature of 60^, a pint of distilled water weighs 7291.2 I grains, a fluidounce 455.7 grains. The Metric System of weights (the word metric is from the Greek j metron, measure) is greatly to be preferred to all others, the i relation of the metric weights of all denominations to measures of ! length, capacity, and surface being so simple as to be within the per- i feet comprehension of a child ; while under the British and American ; plans the weights have no such relation, either with each other or with | the various measures. Moreover the metric system is in perfect har- i mony with the universal method of counting; it is a decimal sy-stem. i [It is perhaps impossible to realize, much more express, the ad- i vantages we enjoy from the fact that in every country of the world i the system of numeration is identical. That system is the decimal. ! Whatever language a man speaks, his method of numbering is deci- | mal ; his talk concerning number is decimal ; his written or printed I signs signifying number are decimal. With the figures 1, 2, 3, 4, 5, ' 6, 7, 8, 9, 0 he represents all possible variation in number, the posi- i tion of a figure in reference to its companions alone determining its value, a figure on the left hand of any other figure in an allocation of numeral symbols (for example, 1871) having ten times the value of that figure, while the figure on the right hand of any other has a ; tenth of the value of that other. When the youngest pupil is asked ' how many units there are in 1871, he smiles at the simplicity of the i question, and says 1871. How many tens? 187, and 1 over. How , many hundreds? 18, and 71 over. How many thousands ? 1, and > 871 over. But if he is asked how many scruples there are in 1871 : grains, how many drachms, how many ounces — he first inquires which ' drachms or which ounces are meant, avoirdupois ounces, troy ounces, ! WEIGHTS AND MEASURES. 455 w wine ounces, and then brings out his slate and pencil. And so with the pints or gallons in 1871 fluidounces, or the feet and yards in 1871 inches, or the pence, shillings, and pounds in 1871 farthings ; to say nothing of cross questions, such as the value of 1871 articles at 2 dollars *and 20 cents per dozen, or of the perplexity caused by the varying values of several individual weights or of measures of length, capacity, and surface in different parts of the country. What is desired is, that there should be an equally simple decimal relation among weights and measures and coins as already universally exists among numbers. This condition of things having already been in- troduced into most other countries, there is no good reason why it should not be accomplished in the United States and Great Britain.] The Metric System of weights and measures is founded on the metre. The engraving represents a pocket folding measure, the tenth part of a metre in length, divided into 10 centimetres, and each centimetre into 10 millimetres. iinp'in TTll|llll iD'iiaj! lUillLIJ. — 12 3 ± Cr^ 6 7 8 9 The Decimetre. The units of the system with their multiples and submultiples are as follows : — Units. Length. — The Unit of Length is the Metre, derived from the measurement of the Quadrant of a Meridian of the Earth. (Prac- tically it is the length of certain carefully preserved bars of metal, from which copies have been taken.) Surface. — The Unity of Surface is the Are, which is the Square of Ten Metres. Capacity. — The Unity of Capacity is the Litre, which is the Cube of a Tenth Part of a Metre. Weight. — The Unit of Weight is the Gram, which is the Weight of that quantity of distilled water, at its maximum density (4^ 0.), which fills a Cube of the One-hundredth part of the Metre. Table. Note . — Multiples are denoted by the Greek words Deka,” Ten, “ Hecto,” Hundred, “ Kilo,” Thousand. Subdivisions, by the Latin words, “ Deci,” One-tenth, ‘ Centi,” One-hundredth, Milli,’’ One-thousandth. Quantities. Length. Surface. Capacity. Weight. 1000 Kilo-metre . . . Kilo-litre Kilo-gram 100 Hecto-metre Hectare Hecto-litre Hecto-gram 10 Deka-metre I)eka-litre l)eka-gram 1 (Units) METRE ARE LITRE GRAM .1 l)eci-metre . . . Deci-litre Deci-gram .01 Centi-metre Centiare Centi-litre Centi-gram .001 Milli-metre Milli-litre Milli-gram 456 QUANTITATIVE ANALYSIS. When the metric method is exclusively adopted these Units and Table, comprising the entire System of AVeights and Measures, re- present all that will be essential to be learned in lieu of the numerous and complicated Tables hitherto in use. Adopting the style of ele- mentary books on Arithmetic, the Table may be expanded in the following manner : — 10 Milligrams 10 Centigrams 10 Decigrams 10 Grams 10 Dekagrams 10 Hectograms make 1 centigram. “ 1 decigram. “ 1 gram. ‘‘ 1 dekagram. “ 1 hectogram, 1 kilogram. 10 Millilitres make 1 centilitre, etc. 10 Millimetres make 1 centimetre, etc. The following approximate equivalents of metrical units should be committed to memory ; — 1 Metre = 3 feet 3 inches and 3 eighths. 1 Are = a square whose side is 11 yards. 1 Litre = If pint. 1 Gramme = ih^ grains. The Metric Ton of 1000 Kilo-grammes = 19 cwt. 2 qrs. 20 lbs. 10 ozs. The Kilo-gramme = 2 lbs. 3f ozs. nearly. The Hect-are = 2^ acres nearly. For exact equivalents, in many forms, see pages 461 and 462. (The word gramme is, in English, usually written gram.) Decimal Coinage . — In most countries where the metric system of weights and measures is employed, a decimal division of coins is also adopted. This course, conjoined with the ordinary decimal method of enumerating, which fortunately is in universal use, renders calcu- lations of all kinds most simple — easy to an extent which cannot be conceived in countries like England, where the operations of weigh- ing, measuring, paying, and counting have only the most absurdly intricate relations to each other. i The General Council under whose authority the British Pharma- j copoeia is issued encourages medical practitioners and pharmacists in j the adoption of the metric sj^stem, and gives the annexed statement j of metric weights and measures. j WEIGHTS AND MEASURES. 457 WEIGHTS AND MEASUEES OF THE METEICAL SYSTEM. (From the British Pharmacopoeia, of 1867.) WEIGHTS. Milligramme = the thousandth part of one grm. or 0.001 grin. Centigramme = the hundredth “ 0.01 “ Decigramme = the tenth “ 0.1 “ Gramme = weight of a cubic centimetre of water at 4^ C. 1.0 ‘‘ Decagramme == ten grammes 10.0 “ Hectogramme = one hundred grammes 100.0 “ Kilogramme = one thousand grammes 1000.0 (1 kilo.) MEASURES OF CAPACITY. 1 Millilitre = 1 cub. centim. or the mea. of 1 gram, of water. 1 Centilitre = 10 “ 10 “ “ 1 Decilitre = 100 “ “ 100 “ “ 1 Litre = 1000 “ 1000 “ (1 kilo.). MEASURES OF LENGTH. 1 Millimetre = the thousandth part of one metre or 0.001 metre. 1 Centimetre = the hundredth “ 0.01 “ 1 Decimetre = the tenth “ 0.1 “ 1 Metre = the ten-millionth part of a quarter of the meridian of the earth. The National Convention for revising the Pharmacopoeia of the United States also recognizes the claims of the metric system of weights and measures by giving, in the recent (fifth) edition of the Pharmacopoeia, Tables of the units of the metrical system with their multiples and submultiples, similar to the foregoing, and the follow- ing Tables showing the relation to each other of the metrical and official or Troy systems. 39 458 QUANTITATIVE ANALYSTS RELATION OF WEIGHTS OF THE U. S. PHARMACOPCEIA TO METRICAL WEIGHTS. Fraction of a grain in Grains in equivalent Drachms, Ounces, and Pounds in equivalent Milligrammes. Metrical weights. metrical weights. Grain. Milligramme. Grains. Centigrammes. Drachms. Grammes. = 1.012 1 = 6.479 1 = 3.887 eV = 1.079 Decigrammes. 2 = 7.775 -50 =3 1.295 2 = 1.295 Decagrammes. 48 = 1.349 3 = 1.943 3 = 1.166 1 ?0 = 1.619 4 = 2.591 4 = 1.555 ih = 1.799 5 = 3.239 5 == 1.943 TU = 2.159 6 = 3.887 6 = 2.332 1 2o = 2.591 7 = 4.535 7 = 2.721 1 2¥ = 2.699 8 = 5.183 Ounces. 1 2 0 = 3.239 9 = 5.831 1 = 3.1103 1 T6 = 4.049 10 = 6.479 2 = 6.2206 1 T3 = 4.319 12 = 7.775 3 = 9.3309 T2 = 5.399 15 = 9.718 Hectogrammes. To = 6.479 Grammes. 4 = 1.2441 i = 8.098 16 = 1.036 5 = 1.5551 i = 10.798 20 = 1.295 6 = 1.8661 T = 12 958 24 = 1.555 7 = 2.1772 i = 16.197 25 = 1.619 8 = 2.4882 k = 21.597 30 = 1.943 9 = 2.7992 1 2 = 32.395 40 = 2.591 10 = 3.1103 50 60 = 3.239 = -3.887 11 = 3.4213 Pounds. 1 = 3.7324 2 = 7.4648 Kilogrammes. 3 = 1.1197 WEIGHTS AND MEASURES. 459 RELATION OP METRICAL WEIGHTS TO WEIGHTS OF THE U. S. PflARMACOPCEIA. Metrical Weights. Exact Approximate Metrical Approximate equivalents in grains. equivalents in grains. Weights, equivalents ® in grains. equivalents in Troy Weight. Milligrammes. Grammes. 1 = .0154 1 ■e? 1 = 15.434 gr. XV. 2 = .0308 1 3 2 2 = 30.868 :^ss. 3 == .0463 2V 3 = 46.302 *9ij- 4 = .0617 tV 4 = 61.736 Si- 5 = .0771 1 T3 5 = 77.170 9iv. 6 = .0926 1 IT 6 = 92.604 5iss. 7 = .1080 1 ■9 7 = 108.038 9vs3. 8 = .1234 1 8 8 = 123.472 5ij* 9 = .1389 1 y 9 = 138.906 9vij. Centigrammes. Decagrammes. 1 = .1543 1 6 1 = 154.340 %iiss. 2 = .3086 i 2 = 308.680 5^- 3 = .4630 A 3 = 463.020 5viiss. 4 = .6173 A 4 = 617.360 5x. 5 = .7717 i 5 = 771.701 Sxiij. 6 =r .9260 To 6 = 926.041 5xv. 7 = 1.0803 1 7 = 1,080.381 Sxviij- 8 = 1.2347 n 8 = 1,234.721 5xx. 9 = 1.3890 u 9 = 1,389.062 3xxiij. Decigrammes. Hectogrammes. 1 = 1.543 n 1 = 1,543.402 .?iiJ 9^. 2 = 3.086 3 2 = 3,086.804 3 = 4.630 3 == 4,630.206 .^ix 3v. 4 = 6.173 6 4 = 6,173.609 Ibi ^vij. 5 = 7.717 5 = 7,717.011 Ibi |iv. 6 = 9.260 9 6 = 9,260.413 Ibi |vij. 7 = 10.803 11 7 = 10,803.816 Ibi gx 3iv. 8 = 12.347 12,1 8 = 12,347.218 ^i.i §i 5^- 9 = 13.890 14 9 = 13,890.620 Ibij gv. Kilogramme. 1 = 15,434.023 J^ij gviij. Myriogramme. 1 = 154,340.23 1 ffixxvi gix. 3 iv. The following Tables, from the British Pharmacopoeia, the United States Pharmacopoeia, and the Diary of Messrs. De La Rue, will be found useful for reference : — WEIGHTS AND MEASURES OF THE BRITISH PHAR- MACOPCEIA OF 1867. WEIGHTS. I Grain gr. I Ounce oz. = 437.5 grains. 1 Pound lb. == 16 ounces = 7000 “ 4G0 QUANTITATIVE ANALYSIS. MEASURES OF CAPACITY. 1 Minim min. 1 Fluidrachm fl. dr. = 60 minims. 1 Fluidounce fi. oz. = 8 fluidrachms. 1 Pint 0. = 20 fluidounces. 1 Gallon c. = 8 pints. MEASURES OF LENGTH. 1 line = L inch. 1 inch = 39 ^^ seconds-pendulum. 12 = 1 foot. 36 “ = 3 feet = 1 yard. Length of pendulum vibrating seconds of mean ] time in the latitude of London, in a vacuum at >39.1393 inches. the level of the sea j (1 cubic inch of distilled water at 62^ F. and 30 inch Barom. = 252.458 grains.) RELATION OF MEASURES TO WEIGHTS. 1 Minim is the measure of 1 Fluidrachm “ 1 Fluidoiince ‘‘ 1 ounce or 1 Pint 1.25 pound or 1 Grallon 10 pounds or 0.91 grain of water, j 54.68 grains of water. | 437.5 “ I 8750.0 ) 70,000.0 RRLATION OF WEIGHTS AND MEASURES OF THE U. S. PH ARMACOPCEIA TO j EACH OTHER. | la distilled water at a temperature of 60^. j One Pound = 0.7900031 Pint = 6067.2238 Minims. One Ounce = 1.0533376 Fluidounce = 505.6013 Minims. One Drachm = 1.0533376 Fluidrachm = 63.2002 Minims. One Scruple = 21.0667 Minims. | One Grain = 1.0533 Minim, j One Gallon = 10.1265427 Pounds = 58328.8862 Grains, i One Pint = 1.2658178 Pound = 7291.1107 Grains. I One Fluidounce = 0.9493633 Ounce = 455,6944 Grains, i One Fluidrachm = 0.9493633 Drachm = 56.9618 Grains, i One Minim = 0.9493 Grain. » RELATION OF MEASURES OF THE U. One Gallon = One Pint = One Fluidounce = One Fluidrachm = One Minim = . PHARMACOPCEIA TO CUBIC MEASURE. 31. Cubic Inches. 28.875 Cubic Inches. 1.80468 Cubic Inch. 0.22558 Cubic Inch. 0.00375 Cubic Inch. I Metrical Measures of Length. WEIGHTS AND MEASURES. 461 T— I ^ CO O CD (M rH CO 00 O O CO (M t— I CO O O O CO (M rH O O O O CO O O O O O CO o o o o o o o o o o o o GO cq CO CO CO oq O CO bJO'O p§ II rC rO CO t> c bo"^ c cq CO cq CO 00 ^ CO in o in o o o o o o CO m lo I— I CO lO 00 I-H CO CO 00 rH ^ CO 00 to -rti CO O to O O to o o o to o o to to o CO to to !— I CO to 00 T i CO CO 00 I _ TjH CO 00 to ^ CO to to CO CO CO CO Oi CO o Cb r— t O O nH O O o o CO rH O O O O CO CO rH O O O CO CO CO T— I O O CO CO CO CO 1— I o 05 CO CO CO CO rH O 05 CO CO CO CO rH O 05 CO CO CO O rH O Oi CO cd rH O 05 CO r-H O 05 rH O rH 05 O 05 (rq O GO O 05 C5 05 (M oq GO O CO 05 05 CO cq CO o GO 05 O CO cq CO O GO o o CO cq CO o o o o o cq o 05 05 05 00 05 ) o cd I GO O 5 cq GO CO cq t-rHOOCDOOOO C0 1'-0t^05000 05 CO t'- I'- o- o o coo5coj:ioi'^o5o O CO^ 05 o 05 o o' cd ^ cd o Oj 05 CO o 00 CO 05 CO 1^- CO 05 CO CO 05 ^ 'H l o C t- c C (?q -fH l!l o 3 s ^S.s eo !C^t^lO (ML'-iOi— l(^qOOO'^ O (M »-0 1— I O OO oocMt'-m,-H(rqo OOOcMl-^iOrHC^ oooocMt^ir:),— I o ^ (rq o CS| O CS| o. o o o r— t- Oi O O 05 o o (rq o (M O O'! o o o o 00 1-^ t" »o o 1'- O 1^- o CO L— o 05 o CO t- o 05 to CO O o 05 to C<1 O O 05 oi o o Ol o O? C<1 CO.— It- CO O !>• I'- CO I I t'- CO o O ^ CO ^ ^ o O t-H ^ to O -C^ O00_ji:^«oor^ rH CO O I— I CO rH I'- iOCOC jO ^ • N ^ 3 o ■5 O 5^ §3 2-2 O ^ ^ ^ .. o o d; a» .T5 (D o o ^ S . 2.2 ° § -f-J o o o ;i; d^ £_ O dJ T3 0^ T3 fc- to ^ O j_ O - O - ^ CJ O •2 3 2 'o g o ^ QJ O -r-H o o o o o o o o o o o o o o .— I O 00 ^ rH O rH 05 CO (Cq O O O 05 GO 'th O O O O 05 CO O O O O O 05 o o o o o o O O O O 0*0 03 OO d d d d d d 0. 0. £3 CO S ‘O H ^ ii S *§ o (cq o i-- CO r^ (cq o o (^q 05 CO GO rH r-* 6X3 o o O i-H 05 CO 00 HH II § o o o O rH 05 CO 00 o o o o O T— H 05 to rA O o o o o O O rH 05 o o o o o O O rH gS d d d d d d d d c II M " m OO m .S oq o UO CO (M rH CO to o 0^ (oq (^q o CD ^^q 1-H ^^q <-: . Si o loq (M o 'cf CO oq rH 3^ to o o (cq (M O CO (cq n3 o o o o (^q C<1 o to o o o o (cq (cq O ‘3 ^ o o o o o - CO ir- O C CO oq rH lO O L'- oq CO S *3 o CO T— ( lO o ir- (oq a ^ o o CO (^q rH uO o 1— ® Ul o o o CO (cq rH lO o o o o o CO (M rH lO O 00 d d d d d CO (M* — j u CO (Oq ^ II CO h-i CQ s CO (Tq CO 05 00 o o ‘3 CO (^q co^ 00 00 o lO CO CQ 00 00 bO .—H KO 00 (M CC 00 rO o rH KO CO (rq CO d d rH rH CO (H CO 'Sd c lO rH lO CO ri^ <^q CO rH lO rH o S=! rH »— ( s = a a p a :: a c rt 2 fc,g s 2 & .“•C S %^S ^ c o ce o o, ^ O G-> >-i • o a s s a c3 2 §D bO.O 1 c:rain = 0.064799 pram. 1 troy =31.103496 prams. 1 lb. av(l.= 0.453593 kilpr. 1 cwt. = 50.802377 kilogrs. SPECIFIC GRAVITY. 463 QUESTIONS AND EXERCISES. 948. Mention some advantages of a decimal system of weights and measures. 949. What is the name of the chief unit of the metric decimal system of weights and measures ? 950. Mention the names of the metric units of surface, capacity, and weight, and state how they are derived from the unit of length. 951. How are multiples of metric units indicated ? 952. State the designations of submultiples of metric units. 953. How many metres are there in a kilometre ? 954. How many millimetres in a metre ? 955. How many grams in 5 kilograms ? 956. How many milligrams in 13j grams ? 957. In 1869 centigrams how many grams ? 958. In a metre measure 5 centimetres wide and 1 centimetre thick how many cubic centimetres ? 959. How many litres are contained in a cubic metre of any liquid? 960. State the British equivalent of the metre. 961. How many square yards in an are ? 962. How many fluidounces in a litre ? 963. How many ounces in a kilogram ? 964. Give the relation of a metric ton (1000 kilos.) to a British ton. 965. How many grains are there in 1 ton ? 966. How many ounces in 1 ton ? 967. How many grains of water in 1 fluidrachm ? 968. How many minims in 1 pint ? 969. How many grains in 1 pint of water ? 970. Whence is the British unit of length derived. Specific Weight or Specific Gravity. The specific weight of a substance is its weight in comparison with weights of similar bulks of other substances. This compara- tive heaviness of solids, and liquids is conventionally expressed in relation to water : they are considered as being lighter or heavier than water. Thus, water being regarded as unity = 1, the relative weight, or specific w^eight, of ether is represented by the figures .720 (it is nearly three-fourths, .750, the weight of water), oil of vitriol by 1.843 (it is nearly twice, 2.000, as heavy as water). The specific weight of substances is, moreover, the weight of similar volumes at sixty degrees (60*^ F.) ; for the weight of a definite volume of any substance will vary according to temperature, becoming heavier when cooled, and lighter when heated, different bodies (gases excepted) differing in their rate of contraction and expansion. While, then, specific weight, or conventionally specific gravity^ is truly the comparative weight of equal bulks, the numbers which in America and Great Britain commonly represent specific gravities are the 4G4 QUANTITATIVE ANALYSIS. comparative weights of equal bulks at 60^ F., water being taken as unity.* The standard of comparison for gases was formerly air, but is now usually hydrogen. « Specific Gravity of Liquids. Procure any small bottle bolding from 100 to 1000 grains, and having a narrow neck ; counterpoise it in a delicate balance ; fill it to about halfway up the neck with pure distilled water having a temperature of 60° F. ; ascertain the weight of the water, and, for convenience, add or subtract a drop or two, so that the weight shall be a round number of grains ; mark the neck by a diamond or file-point at the part cut by the lower edge of the curved surface of the water. Consecutively fill up the bottle to the neck-mark with several other liquids, cooled or warmed to G0° F., first rinsing out the bottle once or twice with a small quantity of each liquid, and note the weights; the respective figures will represent the relative weights of equal bulks of the liquids. If the capacit}" of the bottle is 10, 100, or 1000 grains, the resulting weights will, with- out calculation, show the specific gravities of the liquids ; if any other number, a rule-of-three sum must be w^orked out to ascertain the w^eight of the liquids as compared wdth 1 (or 1.000) of w^ater. Bottles conveniently adjusted to contain 250, 500, or 1000 grains, or 100 or 50 grammes of water, when filled to the top of their perforated stopper, and other forms of the instrument, are sold by all chemical apparatus makers. The following are the stated specific gravities of official liquids : — Acid, acetic, B, P 1.044 “ U. S. P 1.047 diluted, B. B. and U. S. P 1.006 “ “ glacial 1.065 to 1.066 “ carbolic 1.065 hydriodic, diluted 1.112 * The true weight of the body is its weight in air plus the weight of an equal bulk of air and minus the weight of a bulk of air equal to tlie bulk of brass or other weights employed ; or, in other words, its weight in vacuo uninfluenced by the buoyancy of the air ; but such a correction of the weight of a body is seldom necessary or, indeed, desirable. Density is sometimes improperly regarded as synonymous with specific yravity. It is true that the density of a body is in exact proportion to its specific gravity ; but tlie former is more correctly the comparative bulk of equal weights, while specific gravity is the com- parative weight of equal bulks. SPECIFIC GRAVITY. 465 Acid, liydrocliloric, B. P. and U. S. P 1.160 “ “ diluted, B. P 1.052 “ “ U. S. P 1.038 “ hydrocyanic, B. P. and U. S. P 0.997 ‘‘ lactic, U. S. P 1.212 Nitric, B. P. and U. S. P. 1.420 “ ‘‘ diluted, B. P 1.101 “ U. S. P 1.068 “ nitro-hydrochloric 1.074 “ phosphoric diluted, B. P . . 1.080 “ U. S. P 1.056 sulphuric, B. P. and U. S. P 1.843 “ “ aromatic 0.927 “ “ diluted, B. P 1.094 “ “ U. S. P 1.082 “ sulphurous, solution of, B. P 1.040 “ ‘‘ “ U. S. P 1.035 Alcohol, U. S. P 0.835 absolute 0.795 “ (rectified spirit, 84 per cent.) 0.838 “ (proof spirit, 49 per cent.) 0.920 “ dilutum, U. S. P 0.941 “ fortius, U. S. P 0.817 ‘‘ amylic, B. P. and U. S. P 0.818 Ammonia, aromatic spirit of, B. P 0.870 “ stronger water of, U. S. P 0.900 solution of, B. P 0.959 “ strong solution of, B. P 0.891 Antimony, solution of chloride of, B. P 1.470 Arsenic, hydrochloric solution of, B. P 1.009 Arsenical solution [Liquor Arsenicdlis), B. B. . . 1.009 Benzol, B. P 0.850 Bismuth and ammonia, solution of citrate of, B. P. 1.122 Bromine . 2.966 Chlorine solution of, B. P 1.003 Chloroform, B. P. and U. S. P 1.490 “ spirit of, B. P 0.871 Cinchona, liquid extract of yellow, B. P. (about) . 1.100 Creasote, U. S. P 1.046 ‘‘ 1.071 Ether, B. P 0.735 “ U. S. P 0.750 “ pure, B. P 0.720 “ fortior, U. S. P 0.728 Glycerine, B. P. and U. S. P 1.250 Iron, solution of pernitrate of, B. P 1.107 “ “ U. S. P 1.065 “ “ “ persulpate of, B. P 1.441 “ “ U. S. P. .... 1.320 “ strong solution of perchloride of, B. P. . . . 1.338 “ tincture of perchloride of, B. P. and U. S. P. 0.992 466 QUANTITATIVE ANALYSTS. liead, solution of subacetate of, B. P 1.260 “ “ “ ‘‘ “ U. S. P 1.267 Lime, saccharated solution of, B, P 1.052 “ solution of chlorinated, B. P * . . 1.035 Mercury (at 0^ C.= 320 F.) 13.596 “ (at 150.55 C.=:60O F.) 13.560 “ acid solution of nitrate of 2.246 “ “ “ “ “ U. S. P. . . . 2.165 Nitre, sweet spirit of 0.845 “ “ U. S. P 0.837 Oil of mustard, B. P 1.015 Potash, solution of, B. P 1.058 “ ‘‘ “ U. S. P 1.065 Soda, “ B. P 1.047 “ U. S. P 1.071 “ “ chlorinated, B. P 1.103 “ “ ‘‘ “ U. S. P 1.045 Squill, oxymel of, B. P 1.320 Syrup, B. P 1.330 “ U. S. P 1.317 “ of buckthorn, B. P 1.320 “ of ginger “ of hemidesmus, B. P 1.335 “ of iodide of iron, B. P 1.385 ‘‘ of lemons, B. P 1.340 “ of mulberries, B. P 1.330 “ of orange-flower, B. P 1.330 “ of “ peel, B. P “ of phosphate of iron, B. P “ of poppies, B. P 1.320 ‘‘ of red poppy, B. P 1.330 “ of “ roses, B. P 1.335 “ of rhubarb, B. P “ of senna, B. P 1.310 “ of squill, B. P “ of tolu, B. P 1.330 Treacle, B. P (about) 1.400 Hydrometers . — The specific gravity of liquids may be ascertained, without scales and weights, by means of an hydrometer — an instru- ment usually of glass, having a graduated stem and a bulb or bulbs at the lower part. The specific gravity of a liquid is indicated by the depth to which the hydrometer sinks in the liquid, the zero of the scale marking the depth to which it sinks in pure water. Hydro- meters constructed for special purposes are known under the names of saccharometer, galactometer, elmometer, urinometer, alcoliometer. Hydrometers require a considerable quantity of liquid to fairly float them, and specific .gravities observed with them are less delicate and trustworthy than those obtained by the balance, nevertheless they are exceedingly useful for many practical purposes where the employ- ment of a delicate balance would be inadmissible. SPECIFIC GRAVITY. 467 Specific Gravity of Solids in Mass. Weigh a piece (50 to 250 grains) of any solid substance heavier than water in the usual manner. Then weigh it in water, by suspending it from a shortened balance pan by a fine thread or hair and immersing in a vessel of water. The buoyant properties of the water will cause the solid to apparently lose weight ; this loss in weight is the exact weight of an equal hulk of water. The weight of the sub- stance and the weight of an equal bulk of water being thus ascertained, a rule-of-three sum shows the proportional weight of the substance to 1.000 of water. To express the same thing by rule, divide the weight in air by the loss of weight in water, the resulting number is the specific gravity in relation to 1 part of water, the conventional standard of comparison. Verify some of the following specific gravities: — Aluminium 2.56 Antimony 6.71 Bismuth 9.83 Coins, English, gold 17.69 “ ‘‘ silver 10.30 “ bronze 8.70 Copper 8.95 Gold 19.34 Iron 7.84 Lead 11.36 Magnesium 1.74 Marble 2.70 Phosphorus 1.77 Platinum 21.53 Silver 10.53 ■ Sulphur 2.05 Tin 7.29 Zinc 7.14 Specific gravities of solid substances should be taken in water having a temperature of about 60^ F. The body should be im- mersed about half an inch below the surface of the water ; adhering air-bubbles must be carefully removed ; the body must be quite in- soluble in water. Specific Gravity of Solids in Powder or Small Fragments. Weigh the particles; place them in a counterpoised specific-gravity bottle of known capacity, and fill up with water, taking care that the substance is thoroughly wetted ; 468 QUANTITATIVE ANALYSIS. again weigh. From the combined weights of water and substance subtract the amount due to the substance ; the residue is the weight of the water. Subtract this weight of water from the quantity which the bottle normally con- tains ; the residue is the amount of water displaced by the substance. Having thus obtained the weights of equal bulks of water and substance, a rule-of-three sum shows the relation of the weight of the substance to 1 part of water, the specific gravity. Or, suspend a cup, short glass tube, or bucket from a shortened balance-pan; immerse in water; counterpoise; place the weighed powder in the cup, and proceed as di- rected for taking the specific gravity of a solid in mass. This operation may be conducted on fragments of any of the sub- stances the specific gravities of which are given in the foregoing Table, or on the powdered piece of marble the specific gravity of which has been taken in mass. The specific gravity of one piece of glass, first in mass then in powder, may be ascertained ; the result should be identical. The specific gravity of shot is about 11.350; sand, 2.600; mercury, 13.56. , Specific Gravity of Solids Soluble in Water. Weigh a piece of sugar or other substance soluble in i water; suspend it from a balance in the usual manner, and ■ weigh it in turpentine, benzol, or petroleum, the specific gravity of which is known or has been previously deter- mined ; the loss in weight is the weight of an equal bulk of the turpentine. Ascertain the weight of an equal bulk of water by calculation. Sp. gr. of , sp. gr. of ^ ^ observed ^ equal bulk turpentine ' water * ’ bulk of turp. ’ of water. The exact weights of equal bulks of sugar and water being obtained, the weight of a bulk of sugar corresponding to one of water is shown by a rule-of-three sum ; in other words, divide the weight of sugar hy that of the equal bulk of water, the quotient is the specific gravity of sugar. The specific gravity of sugar ranges from 1.06Y to 1.090. Specific Gravity of Solids Lighter than Water. This is obtained in a manner similar to that for solids heavier than water; but the light body^ is sunk by help of a piece of heavy metal, the bulk of water which the hitter displaces being deducted from the bulk displaced by both;. SPECIFIC GRAVITY. 409 the remainder is the weight of a bulk of water equal to the bulk of the light body. For instance, a piece of wood weighing 12 grammes (or grains) is tied to a piece of metal weighing 22 grammes, the loss of weight of the metal in water having been previously found to b^e 3 grammes. The two, weighing 34 grammes, are now immersed, and the loss in weight found to be 26 grammes. But of this loss 3 grammes have been proved to be due to the buoyant action of the water on the lead; the remaining 23, therefore, re- present the same effect on the wood; 23 and 12, therefore, represent the weights of equal bulks of water and wood. As 23 are to 12 so is 1 to .5211. Or, shortly, as before, divide the weight in air by the weight of an equal bulk of water; .5217 is the specific gravity of the wood. Another specimen of w^ood may be found to be three-fourths (.750) the weight of water, and others heavier. Cork varies from .100 to .300. Specific Gravity of Gases. This operation is similar to that for liquids. A globe exhausted of air and holding from 1 to 4 litres (or quarts) is suspended from the arm of a balance, and counterpoised by a similar flask. ^Gases are introduced in succession and their weights noted. A rule-ot-three sum shows their specific gravity in relation to air or hydrogen, which- ever be taken as a standard. Correction of the Volume of Gases for Pressure. — The height of the barometer at the time of manipulation is noted. Remembering the fact that “ the bulk of a gas is inversely as the pressure to which it is subjected” (Boyle and Mariotte), a simple calculation shows the volume which the gas would occupy at 760 millimetres (or 29.922 inches), the standard pressure. (30 inches is sometimes adopted as the standard in England."^) Thus, 40 volumes of a gas at 740 milli- metres pressure are reduced to 39 when the pressure becomes 760 millimetres (or 90 vols. at 29 ins. barom. become 87 vols. at 30 inches) . Correction of the Volume of Gases for Temperature. — This is done in order to ascertain what volume the gas would occupy at 0^ C. (32° F!) or 15^.5 C. (60° F.), according to the standard taken. * In France the conventional standard height of the barometer is 760 millimetres at OO C. (32P F.) ; in England it is 30 inches, the temperature of the mercurial column being 60P F. 760 millims. is equivalent to 29.922 inches ; but the expansion of th-e metal between 320 F. and 60° F. increases the length of the column to 30.005 inches. The standards are, therefore, almost identical, difference in true length being counterbalanced by the temperature at which the length is observed. 40 470 QUANTITATIVE ANALYSIS. Gases expand about 0.3665* per cent, of their volume at the freezing-point of water for every C. degree (0.2036, or ^ for every F. degree) (Kegnault). Thus 8 volumes of gas at 0^ C. will become 8.293 at 10^ C. ; for if 100 become 103.665 on being increased in i temperature 10^ C., 8 will become 8.293 (or if 100 become 102.036 i on being increased 10^ F., 8 will become 8.1629). | Vapor-density. — Vapors are those gases which condense to liquids' at common temperatures. By the density of a vapor is meant its specific gravity. The density of a vapor is the ratio of any given volume to a similar volume of air or hydrogen at the same tempera- ture and pressure. But, for convenience of comparison, this experi- mental specific gravity is referred, by calculation as just described for permanent gases, to a temperature of 0^ C., and 760 millimetres j barom. A teaspoonful or so of liquid is placed in a weighed flask of | about the capacity of a common tumbler and having a capillary i neck ; the flask is heated in an oil-bath to a temperature considerably j above the boiling-point of the liquid ; at the moment vapor ceases | to escape, the neck is sealed by a blowpipe-flame, and the tempera- ture of the bath noted ; the flask is then removed, cooled, cleaned, and weighed ; the height of the barometer is also taken. The neck of the flask is next broken off beneath the surface of w^ater or mer- cury (which rush in and fill it), and again weighed, by which its capa- city in cub. centims. is found. From these data the volume of vapor yielded by a given weight of liquid is ascertained by a fcAv obvious calculations. The capacity of the globe having been ascertained, the Tveight of an equal bulk of airf is obtained by a rule-of-three sum. This weight of air is deducted from the original w^eight of the flash, which gives the true weight of the glass. The weight of the glass is next subtracted from the weight of the flask and contained vapor (now condensed), which gives the weight of material used in the experiment. The volume which this weight of material occupied at the time of experiment is next corrected for temperature (to 0*^0.) and pressure (760 millimetres) in the manner just described. The weight of a similar volume of hydrogen is nextfound.t The weights ^ of equal volumes of hydrogen and vapor being thus determined, the I amount of vapor corresponding to 1 of hydrogen (the specific gravity j * Corrected for the difference between the mercurial and air ther- ( mometers the coefficient of expansion of air is 0.003656 (Miller), f Gases vary slightly. | f 1 cub. centim. of air at 0° C. and 760 millims. weighs 0.001293 * gramme. I t 1 litre (1000 cub. centims.) of hydrogen at 0° C. and 760 milli- f metres (the barometer being at OOC.) weighs 0.0896 gramme — a vol- ^ ume sometimes termed a crith (from krithe^ a barley-corn— figu- i; ratively, a small weight) ; thus a litre of oxygen weighs 16 criths, \i chlorine 35 5 criths, etc. 100 cubic inches of hydrogen at 320 p, j| weigh 2.265 grains; at 600 p. 2.143 grains (the barometer being 30 j‘ ins. at 600 p. in both cases). 100 cubic inches of air at 320 F. weigh 32.698 grains ; at 600 p , 30 935 (barom. 30 ins at 600 p ). i cubic ( inch of water weighs 252.5 (252.458 at 620 F , and 30 in bar.) grains. 1 gallon of water contains 2771 (277,274 at 620 p ) cubic inches. : SPECIFIC GRAVITY. ill or vapor-density) is shown by a short calculation. This process of finding the weight of a given volume of vapor is by Dumas. Gay- Lussac's consists in determining the volume of a given weight. Experiment shows that the specific gravities of many gases and vapors on the hydrogen scale and the proportions in which they com- bine by weight are identical. Thus, chlorine is 35.5 times as heavy as hydrogen, and 35.5 parts unite with 1 of hydrogen to form hydro- chloric acid gas. Hence, if the specific gravity of a gas or vapor is known, its combining proportion may be predicated with reasonable certainty, and vice versa. In applying this rule to gaseous or vapor- ous compounds, attention must be paid to the extent to which their constituent gases contract *at the moment of combination or expand at the moment of decomposition. Thus, steam is found to be com- posed of two volumes of hydrogen and one of oxygen, the three vo- lumes of constituents condensing to two at the moment of combina- tion. Hence, steam may be expected to be nine times as heavy as hydrogen, which experiment confirms. These relations may be so expressed as to include both elementary and compound gases and vapors, thus : molecular weights and spe~ cific weights are identical. Molecular weights represent two vo- lumes of a gas ; specific gravity conventionally represents the relative weight of a gas compared with one volume of hydrogen or air ; hence the specific gravity of a gas or vapor on the H scale is found by cal- culation on simply dividing the molecular weight by 2 ; on the air- scale by dividing the hydrogen numbers by 14.44. For example, — Molecular Name. formula. Hydrogen, H^ Chlorine, Cl.^ Oxygen, O.^ Nitrogen, Steam, H.^0 Ammonia gas, NHg Carbonic acid gas, CO.^ Alcohol (vapor), _ C.^H^O Air, Molecular weight. H=2. 2 2 71 71 32 32 28 28 18 18 17 17 44 44 46 46 28.88 Specific gravity. H = 1. Air = 1. 1 .069 35.5 2.460 16 1.108 14 .970 9 .624 8.5 .589 22 1.524 23 1.593 14.44 1.000 These specific gravities closely correspond with those obtained by actual experiment. The specific gravity of any gas or vapor may therefore be calculated if the following data are at hand : [a) for- mula, (&) atomic weight of constituent elements ; these give the molecular weight, and the molecular weight divided hy 2 is the specific gravity on the hydrogen-scale. Specific gravity on the air- scale is then deducible, if (c) the specific gravity of air (14.44) in relation to hydrogen be remembered. The absolute weight of any volume of a gas or vapor on the metric system is then obtainable if [d] the weight of a litre of hydrogen (0.0896 gramme) be known, or on the English plan by remembering (e) that 100 cubic inches of hydrogen at 60^ F. weigh 2.143 grains (100 cubic inches of air at 60^ F. weigh 30.935 grains). In confirmation of these statements regarding the mutual relation 472 QUANTITATIVE ANALYSIS. of specific gravity and atomic weight, a remarkable fact may be mentioned. Eegnault several years ago found the weights of 1 litre of hydrogen and oxygen to be respectively .089578 and 1.429802 gramme. The latter number divided by the former gives 15.96 as the specific gravity of oxygen. Stas, in recent experimental researches on combining-proportion, finds the atomic weight of oxygen to be not 16, but 15.96. Exceptions to the law occur in a few compounds and in arsenicum and phosphorus, whose vapor-densities are twice that indicated by i the rule. | Relation of the Specific Heat of Elements to their Atomic j Weights . — Eeference may here appropriately be made to a physical i fact of great importance as regards molecular and atomic weights. I In the earlier pages of this manual it was stated that elements do not j combine chemically in haphazard proportions, but in fixed weights ; ^ and abundant evidence of the truth of the statement has already been ! afforded, and will also be found in this section on quantitative analysis. : Secondly, it has been shown that elements do not combine in hap- ■ hazard proportions by volume, but in certain constant bulks ; and ' the weights of these bulks have been found to be identical with the ; combining weights themselves. Thirdly (and this is the point to ; which attention is drawn), if equal amounts of heat be given to ele- ments in the solid state (that is, to solid elements or solid compounds i of volatile elements), and the quantity of the element be increased or diminished until each is thus heated through an equal number of de- | grees, it will be found that the different weights of elements required i are (in relation to a common standard) identical with the combining ; weights of the elements, and with the weights of the combining vol- umes of the elements. Thus, where 108 parts of silver would be em- ; ployed, 207 of lead would be necessary. Hence, in the determination ' of (a) combining-proportion, (b) specific gravity in gaseous state, and (c) specific heat, three distinct methods of ascertaining atomic weight are available. In cases where one method is inapplicable recourse is had to either or, if practicable, both of the others, and thus the trust- worthiness of observations and generalizations placed more or less ^ beyond question. The specific heat of a solid dementis the same in > the free as in the combined condition ; therefore the specific heat of \ a molecule is the sum of the specific heats of its constituent atoms. } From the specific heat of a solid compound of a volatile element (chlo- t rine, for example) can thus be calculated the specific heat of an ele- ! ment in the solid state, even though the free element cannot itself be | solidified. For the processes by which experimentally to determine j specific heat the reader is referred to books on physics. QUESTIONS AND EXEECISES. 971. Define specific weight, or as it is commonly termed, specific | gravity. ! 972. In speaking of light and heavy bodies especially, what stand- ' ard of comparison is conventionally employed ? QUESTIONS AND EXERCISES. 473 973. How are specific gravities expressed in figures ? 974. Why should specific gravities be taken at one constant tem- perature ? 975. How does the buoyancy of air affect the real weight of any material ? 976. Describe the difference between density and specific gravity. 977. Give a direct method for the determination of the specific gravity of liquids. 978. A certain bottle holds 150 parts, by weight, of water, or 135.7 of spirit of wine; what is the specific gravity of the latter? Ans. 0.9046. 979. Equal volumes of benzol and glycerine weigh 34 and 49 parts respectively, and the sp. gr. of the benzol is 0.850 ; what is the spe- cific gravity of the glycerine ? Ans. 1.225. 980. Explain the process employed in taking the specific gravity of solid substances in mass and in powder. 981. State the method by which the specific gravity of a light body, such as cork, is obtained. 982. What modifications of the usual method are necessary in ascertaining the specific gravity of substances soluble in water? 983. How is the specific gravity of gases determined ? 984. By what law can the volume of a gas, at any required pres- sure, be deduced from its observed volume at another pressure ? 985. To what extent will 78 volumes of a gas at 29.3 inches ba- rometer alter in bulk when the pressure, as indicated by the barometer, is 30.2 inches ? 986. Write a short account of the means by which the volumes of gases are corrected for temperature. 987. At the temperature of 15^ C. 40 volumes (litres, pints, ounces, cubic feet, or other quantity) of a gas are measured. To what ex- tent will this amount of gas contract on being cooled to the freezing- point of water (0^ C.) ? Ansiver. As 1 vol. of any gas at zero expands or contracts .003665 of a vol. for each rise or fall of 1^ C., 1 vol. at 0° C. if heated to 15^ C. will become increased by .054975 (that is .003665 multiplied by 15), 1 vol. will expand to 1.054975. Conversely, 1.054975 vol. will contract to 1 vol. if cooled from 15^ C. to 0*^ 0. And if 1.054975 becomes 1 in cooling through 15^ C., 40 vols. will (as found by rule- of-three) contract to 37.916. (The following five problems and solutions are from Williamson’s “ Chemistry.”) 988. 10 litres of oxygen are measured off* at 14^ F. Kequired the volume of the gas at 15^ C. Answer. The first operation must be to reduce the temperature quoted in Fahrenheit’s degrees to an equivalent value on the Centi- grade scale. 14^ F. is 18^ below 32° F., the freezing-point of water ; and a range of 9° on khe Fahrenheit’s scale is equal to a range of 5^ on the Centigrade scale, so that the temperature at which the oxygen is measured off is — 10^ C. The rise of temperature up to 0^ expands the gas in such proportion that its volume at 0^ is to its volume at —10'^ as 1 is to 1 — 0.03665, ^. e. as 1 to 0.96335. The further rise 40 * 414: QUANTITATIVE ANALYSIS. of temperature from 0^ C. to 15^ expands the gas in the proportion of 1 to 1-1-15x0.003665; t, e. 1 to 1.054975. 4’he total rise of tem- perature therefore expands the gas in the proportion of 0.96335 to 1.054975. 0.96335 : 1.054975 : : 10 : x; 10 X 1.054975 ^ ~ 0.96335 ~ 989. 230 cubic centimetres of oxygen are measured off at 14^ C. and 740 millimetres mercurial pressure. Eequired the volume of the gas at the normal temperature and pressure (0*^0. and 760 millime- tres). Ansiuer. Let the reduction for change of temperature be made first. The proportion gives 1 -L 14 X 0.003665 : 1 :: 230 230 1.05131 218.774 To reduce this volume at 740 millimetres pressure to the volume i corresponding to the pressure of 760 millimetres, we have the pro- j portion 38 :37 :: 218.77 :x; whence X = 37 X 218.77 38 213.02. 990. A litre of oxygen is confined in a glass flask at 10^ 0. by the ; atmospheric pressure, added to that of a column of mercury 60 milli- • metres high. The flask must be heated to 300^ C. without any in- * crease of volume taking place in the oxygen. How high must the * column of mercury then be which presses on the gas, supposing the ' atmospheric pressure to remain constant at 760 millimetres ? Anstver. The oxygen is given at 10^ 0. and 820 millimetres , pressure. If the pressure remained constant, the rise of temperature i from 10^^ 0. to 300*^ G. would expand the gas in such proportion that : 1.03665 volume would expand to 2.0995 volumes. In order to pre- vent any expansion the pressure must be increased in the same pro- portion, whence 1.03665 : 2.0995 : : 820 : x; 820 X 2.0995 1.03665 ~ 1660.6. From this total pressure the atmospheric pressure of 760 millimetres has to be deducted, leaving 900.6 millimetres as the height of the required mercurial column. ! 991. A litre of oxygen is required of the density of 100 at 0^ C. ‘ What weight of potassic chlorate must be used for its preparation, and what total pressure must be applied to it ? Ansxoer. The pressure required to compress oxygen froin the den- ; sity of 16 to that of 100 is found by the proportion VOLUMETRIC ANALYSIS. 475 16 : 100 : : 760 :x; 76000 X = ~T7r- = 4750. Id At the pressure of 4750 millimetres of mercury the weight of a litre of oxygen (16 grammes measure 11.2 litres at 0^ 0. and 760 millims. pressure) is found by the proportion 760 :4750 : : : x ; 11.2 ' whence — X 4<50 _ g grammes. ^■“ 11.2 x 760 ^ The weight of chlorate required for the evolution of 8.93 grammes of oxygen is found from the proportion 48 : 122.5 : : 8.93 :x; .\x=22.S grammes. 992. What is the volume of 12 grammes of hydrogen at 15^ C. ? Answer. One gramme of hydrogen measures 11.2 litres at 0^ C., therefore 12 grammes measure 12 X 11.2 = 134.4 litres at 0^. To find their volume at 1.5^ C. we have the proportion 1 : 1 + 15 X 0.003665 : : 134.4 : x; whence ir=134.4 X 1.054975 = 141.788 litres. 993. What interest for chemists have the specific heats of sub- stances ? • VOLUMETRIC ANALYSIS. {See the Introductory Remarlcs to Quantitative Analysis.) APPARATUS. The only special vessels necessary in volumetric quantitative ope- rations are \ 1. A litre flask, which, when filled to a mark on the neck, contains one litre (1000 cubic centimetres, i. e., 1000 grammes of water*) ; it serves for preparing solutions in quantities of one litre. 2. A tall, cylindrical graduated litre jar divided into 100 equal parts ; it serves for the measurement and admixture of deci- mal or centesimal parts of a litre. 3. A graduated tube or burette, which, when filled to 0, holds 100 cubic centimetres (a decilitre), and * A cubic centimetre is, strictly speaking, the volume occupied by one gramme of distilled water at its point of greatest density, namely, 40 C. ; metrical measurements, however, are uniformly taken at 150.55 C. (600 F.). 476 QUANTITATIVE ANALYSIS. is divided into 100 equal parts ; it is used for accurately measuring small volumes of liquids. The best form of a burette is Mohr’s. It consists of a glass tube about the width of a little finger and the length of an arm from the elbow, contracted at the lower extremity and graduated. To the contracted portion is fitted a small piece of vulcanized caoutchouc tubing, into the other end of which a small spout made of narrow glass tube is tightly inserted. A strong wire clamp effectually pre- vents any liquid from passing out of the burette unless the knobs of the clamp are pressed by the finger and thumb of the operator, when a stream or drop flows at will. The accurate reading of the height of a solution in the burette is a matter of great importance ; it should be taken from the bottom of the curved surface of the liquid. It may be still more exactly measured in operations of special delicacy by the employment of a hollow glass float or bulb (Erdmann’s float), of such a width that it can move freely in the tube without undue friction, and so adjusted in weight that it shall sink to more than half its length in any ordinary liquid. A fine line is scratched round the centre of the float ; this line must be always regarded as marking the height of the fluid in the burette. In charging the burette, a solution is poured in, not until its surface is coincident with 0, but until the mark on the float is coincident with 0. ESTIMATION OE ALKALIES, ETC. An equation represents much more than the formation of certain substances from others. Thus 2NH,HO + H^C^O,, 2H,0 = (NHJ^O^O^, H,0 + SH^O Amraouia. Crystallized Oxalate of Water, oxalic acid. ammonium. not only shows that oxalate of ammonium is produced when ammo- nia and crystallized oxalic acid are mixed together, but among other facts, that 70 parts of ammonia and 126 of oxalic acid yield 142 of crystallized oxalate of ammonium and 54 of water. For formulae represent molecules ; the weight of a molecule is the sum of the weights of atoms ; and atomic weights are represented by definite in- variable numbers (see the Table of atomic weights in the Appendix). As 126 parts (= I molecule) of oxalic acid combine with 70 parts (= 2 molecules) of ammonia, 63 (half of 126) of oxalic acid will unite with 35 (= ] molecule) of ammonia (NH^HO); 63 parts of oxalic acid will also unite with 56 of caustic potash (KHO = 56), 40 of caustic soda (NaHO=40), 100 of acid carbonate of potassium (KIIC0.5== IOO), 69 of anhydrous carbonate of potassium (K 2 C 03 = 138), 84 of acid carbonate of sodium (NaHC 03 = 84), 53 of anhy- drous carbonate of sodium (Na 2 C 03 = 106), or 143 of crystallized carbonate of sodium (Na^OO-p lOH.^O == 286). And if 63 parts of oxalic acid be dissolved in 100 volumes of water, the stated weights of these various salts should be exactly neutralized by such a solu- tion. 143 parts of crystallized carbonate of sodium, for instance, VOLUMETRIC ESTIMATION OF ALKALIES. 477 should, if pure, be exactly neutralized by the 100 volumes of the oxalic acid solution ; and if a less number of volumes is required, the salt is so much per cent, impure. 143 parts by weight of a commer- cial sample of carbonate of sodium (common washing “soda”) re- quiring only 97 of the standard oxalic acid solution is thus shown to contain 97 per cent, of pure carbonate of sodium, the remainder being impurities. Further, the strength of solutions of ammonia, soda, potash, and lime may be accurately determined by adding to any definite quantity of them gradually, from a burette, a solution containing oxalic acid in known quantity, until exact neutralization is effected. If the quantity of oxalic acid required be 63 parts by weight (or 100 volumes of solution of oxalic acid containing 63 parts, by weight, of the crystals), then the quantities of alkaline so- lutions employed contain, of potash (KHO) 56 parts by weight, of soda (NaliO) 40, of ammonia (NH^IIO) 35 parts, of slaked lime (Ca2HO) 37, anhydrous lime (CaO) 28, etc. The strength of an alkaline solution, or, in other words, the proportion required to effect neutralization of 100 volumes of the oxalic acid solution, having once been determined and decided by authority (B. P. e, g.), that quantity may always be expected to take 100 volumes of the oxalic acid liquid ; if less is required, the alkaline liquid is so much per cent. weak. The exact point of neutralization of acid or alkaline liquids is ex- perimentally ascertained by litmus paper, or, more generally, infusion of litmus, which is turned red by the slightest amount of free acid, and blue by alkali. Standard Solution op Oxalic Acid. (Crystallized Oxalic Acid, H^C.^O^, 2H20=126.) On account of the bivalent character of the oxalic radi- cal and the univalent character of most of the metals contained in the salts which are estimated by oxalic acid, it is convenient to take half the molecular weight of the acid for experiments, with the whole of the molecular weights of salts of univalent basylous radicals. Tlie oxalic acid must be pure, leaving no ash when' a gramme or so is heated to redness in a porcelain or platinum cruci- ble; it must also be quite dry, but not effloresced. Place 63 grammes of the crystals in a litre flask, add distilled water and shake till dissolved, diluting until the solution, at about 60° F., has an exact volume of 1 litre. Preserve in a stoppered bottle. 100 cubic centimetres of this solution contain of the molecular weight of oxalic acid in grammes, and will neutrallize of the molecular weight in grammes, of a salt containing one atom of certain bivalent metals (as Ca2lIO), or a salt (Na^CO^ e. g.) containing two atoms of univalent metals, or of the molecular weight in grammes 478 QUANTITATIVE ANALYSIS. of salts containing one atom of univalent radicals (such as KHCO3). The following official substances are tested with this solution. In those which are fluid there is commonly a slight variation in strength according as they are made by formulae of the British or U. S. Pharmacopoeia. Grammes of C. c. of substance. vol. sol. * Ammonia, solution of 17.00 = “ strong solution of 5.23 = Ammonium, carbonate of, B. P. and U. S. P. 5.90 — Borax, B. P. and U. S. P 19.10 = Lead, acetate of, B. P. and U. S. P. . . 9.50 = “ sol. of subacetate of, B. P. and U. S. P. 51.02 = Lime, aqueous solution of, B. P. and U. S. P. 438.00 = “ saccharated sol. of, 45.30 = Potash, caustic, B. P. and U. S. P. . . . -5.60 = “ solution of 48.02 = “ water, effervescing 292.00 = Potassium, bicarbonate of, B. P. and U. S. P. 5.00 = “ acid tart, of, B. P. and U. S. P. 18.80 = “ carbonate of, B. P. and U. S. P. 8.30 = “ citrate of, B. P. and U. S. P. . 10.20 = “ tartrate of, B. P. and U. S. P. . 11.30 = Soda, caustic, B. P. and U. S. P 4.00 = “ solution of 48.72 = “ water, effervescing 246.07 = Sodium, bicarbonate of, B. P. and U. S. P. 8.40 = “ and potassium, tart, of, B.P. and lT.S.P.14.10 = “ carbonate of, B. P. and U. S. P. . 14.30 = 100.0 100.0 100.0 100.0 50.0 100.0 20.0 25.0 90.0 to 100.0 50.0 10.0 50.0 100.0 98.0 to 100.0 100.0 100.0 90.0 to 100.0 50.0 10.0 100.0 100.0 96.0 to 100.0 Note 1. — The several substances diluted or dissolved, as described in the following paragraphs, are conveniently placed in a beaker, and the solution of acid run in cautiously from the brunette. Note 2. — A smaller number of c. c. of volumetric solution than 100, and a corresponding amount of substance to be tested, may be employed in any case. But to ascertain percentage of impurity in the substance, the amount corresponding to 100 c. c. of the vol. sol. must be considered to have been used, the number of c. c. then wanting to make up 100 is the percentage of impurity. The solutions of ammonia require only the addition of solution of litmus, and the acid cautiously^ added until the last drop turns the liquid red. The amount of acid used previously to the addition to the portion that reddened the litmus indicates the proportional purity of the alkaline liquid. Thus, if only 50 c. c. are requirecT, the solution is * The reading of the Table maybe amplified thus: 17 grammes of the official Solution of Ammonia ( AwV/uor B. P.), carefully weighed, will require, for complete neutralization, if of full strength, 100 cubic cemtimetres of the official volumetric solution of oxalic acid. VOLUMETRIC ESTIMATION OF ALKALIES. 479 only half as strong as it ought to he ; if 93 c. c. are needed, the sol. of ammonia is 7 per cent, too weak, and so on. The actual quantity of ammonia (NH^HO) or ammoniacal gas (NH3) in the solutions is readily ascertained by calcu- lations, thus: 100 c. c. of the acid solution have been em- ployed ; these contain 2V molecular weight of oxalic acid in grammes=6.3, and have neutralized of the mo- lecular weight of ammonia in grammes = 3.5 (or 1.7 of NH3) ; 5.23 parts, by weight, of strong solution of ammonia (the amount employed in the experiment) contain, therefore, 3.5 of ammonia, NH^HO, or 1.7 of ammoniacal gas NH.^; now if 5.23 parts of a solution contain 3.5 of real ammonia (NH4HO), 100 parts will contain (by riile-of-three calcula- tion) 67, and if the 5.23 contain 1.7 part of ammonia gas (NH3), 100 will contain 32.5 ; hence the Strong Solution of Ammonia, supposed to have been under examination, con- tains 67 per cent, of the hydrate or 32.5 per cent, of the gas. The formulae and molecular weights representing this process are as follows : — 2NH,HO (or 2NH3) H,C^O,,2H,0 70 34 126 The carhonate of ammonium should be dissolved in 30 or 40 c. c. of distilled water, infusion of litmus added, the standard oxalic acid solution allowed to flow in until the well-stirred liquid assumes a purple hue (due to the in- fluence of carbonic acid on the litmus), the whole gently warmed to promote evolution of carbonic acid gas, more standard acid then dropped in until the liquid again be- comes purple, heat once more applied, and the operation continued until the last drop of acid turns the solution red; the height of the column of liquid in the burette before the last drop escapes represents the true amount of standard solution used, and hence the percentage of real carbonate of ammonium (of ofiicial quality) in the specimen on which the experiment was performed. The solution must be heated with care, or ammonia will escape. (Prac- tised analysts usually add excess of the standard acid and thus flx every trace of ammonia ; then gently boil to get rid of carbonic acid gas ; bring back the liquid to neutrality by an observed volume of standard alkaline solution, and deduct an equivalent volume of acid from the quantity first added.) The formulae and molecular weights representing the process are as follows : — 480 QUANTITATIVE ANALYSIS. N,H.„C 30 , + 2 (II,C 30 „ 2 H, 0 ) V ^ s ^ 236 252 {vide p. 78) (2 molecules) As 252 parts of oxalic acid neutralize 236 of the so-called carbonate of ammonium, 6.3 of acid (or 100 vols. of its solution) will neutralize 5.9 of carbonate. If 5.9 grammes of carbonate be the quantity emplo 3 ^ed, and it does not require 100 c.c. of the volumetric solution, it is so much per cent. weak. Thus, if say 94 c. c. neutralize the salt, the latter is 6 per cent. Tveak (some ammonia gas has escaped, and, consequently, an abnormal amount of acid carbonate NH^HCO.., is present). Any smaller quantity of salt than 5.9 grammes may be used ; in that case a rule- | of-three sum must be worked to show how many c.c. of i vol. sol. would have been employed if 5.9 grammes had i actually been the amount under experiment. The borax should be dissolved in several ounces of dis- tilled water. The formulae and molecular weights repre- senting the process are as follows : — 2NaBO„BA,10H,O + 382 126 The solutions of the acetates of lead in distilled water i may be rendered clear by the addition of a few drops of acetic acid. They must be well stirred after each addition i of the solution of oxalic acid. The action is complete when the last drojj of acid produces no more precipitate (oxalate of lead). Pb2C,H,0„ 3H.p + 2H,0 Pb.p2C,H30., + 2(H,C,0,, 2H,0) 548 252 The solutions of lime require similar treatment. Ca2HO (or CaO) -f 2H.,0 Solid caustic 2^otash or soda is never met with in a state of chemical purity, but should contain not less than 90 per cent, of the hydrate of potassium or sodium. The stand- ard acid is added to an aqueous solution of the hydrate, VOLUMETRIC ESTIMATION OF ALKALIES. 481 tlie termination of the action between the alkali and acid being observed by aid of litmus. If carbonic acid be present, the mixture must be gently boiled before a final reading of the amount of acid added is taken. 2 KHO or 2 ]S'aHO + 2H,0 112 80 126 The alkaline carbonates are often moist, and include traces of sulphates, chlorides, and silicates, but are suffi- ciently pure if containing, in the case of carbonate potas- sium 98 per cent., and carbonate of sodium 96 per cent., of the respective crystalline salts. The volumetric manipula- tions with these salts are similar to those for carbonate of ammonium. The strength of soda-ash is often reported in terms of “soda,’’ that is, oxide of sodium (Na 20 = 62). The old molecular weight of carbonate of sodium, 54 (it should have been 53), derived from that of “ soda,” 32 (it should have been 31), is still employed in Great Britain in reporting the strength of soda-ash. The true amount of soda equivalent to 54 parts of carbonate is 31.41 parts. A modern analyst having found the true amount of soda in a sample of soda-ash is expected by some manufacturers to report 31.41 parts for every 31, and 54 of carbonate instead of 53, and other quantities in proportion to these figures. 2 KHCO 3 -f 2H,0 2NaHC03 + II,C,0„ 2H,0 200 126 K,C 03 + II,CA,2H,0 138 126 168 126 Na,^3 + 106 126 K,C 03 of 84 % 4 -HA 04 , 2H,0 16Tr285 126 Nu.CO,, 1QH,0 +H,OA,2H,0 286 126 One molecule of tartrate of potassium^ or two of the acid tartrate^ yields one of carbonate when burnt, two molecules of citrate yielding three of carbonate under the same cir- cumstances. Two molecules of tartrate of potassium and sodium yield one of potassium carbonate and one of sodium carbonate. A volumetric estimation of the amount of carbonate thus produced aifords indirect means of quan- titatively determining the purity of the original salts. 41 482 QUANTITATIVE ANALYSIS. eq. to 2H,0 V > V > 226 126 2KHC,H,0, eq. to 11,0,0,, 2H,0 ' y ' ' y ' 376 126 2K3C,H,0, eq. to 3H,C,0„ 2H,0 612 378 NaKC,H,0„ 4H,0 eq. to H,C,0„ 2H,0 ' Y ' *■ V ^ 282 126 Alkalimetry, — The foregoing processes are often spoken of as those of alkalimetry (the measurement of alkalies). Notes. Neutral solution of litmus is prepared by digesting the commercial fragments in about fifteen or twenty times their weight of water for a few hours, decanting, dividing into two equal portions, adding acid to one till it is faintly red, then pouring in the other, and mixing. The solution may be kept in a stoppered bottle, but occasionally exposed to the air. It should never be filtered, but gradually allowed to deposit. Standard sulphuric acid may be used in the place of oxalic acid if the latter cannot readily be obtained in a state of purity, 100 c. c. of the liquid containing Aq of the molecular weight of the pure acid in grammes. It is pre- pared by diluting oil of vitriol with from three to four times * its bulk of distilled water, ascertaining how much of the acid liquid is required to exactly neutralize of the mo- lecular weight of pure carbonate of sodium, taken in grammes (5.3), and adding water until the observed volume - of acid is increased to 100 c. c. Pure anhydrous carbon- ate of sodium (Na.^CO.J is obtained by heating the pure bicarbonate to dull redness in a platinum or porcelain cru- cible for about a quarter of an hour. The commercial ] bicarbonate should be tested for chlorides and sulphates,, which are usually present in small quantities. Two or three hundred grammes ma}" be purified by washing first with a , saturated solution of bicarbonate of sodium and then coldi distilled water until all trace of impurity has disappeared,, drjdng over a water-bath, and then igniting to convert into . carbonate. VOLUMETRIC ESTIMATION OF ACIDS. 483 Other quantities of salts than those stated in the foregoing and following Tables may be employed in volumetric determinations, cal- culation giving any desired form to the experimental results, an expert analyst thus saving much time and material. In the case of substances which are liable to alter by exposure to air, it is important that a selected quantity should be quickly weighed, rather than selected weights be accurately balanced by material, the former operation occupying much the shorter time. Salts other than the official may be quantitatively analyzed by the volumetric solutions, slight modifications of manipulation even enabling the processes to be adapted to fresh classes of salts. Ample instructions for extending operations in this manner will be found in Sutton’s “Handbook of Volumetric Analysis.” QUESTIONS AND EXERCISES. 994. Describe the various pieces of apparatus used in volumetric deternrinations. 995. One hundred cubic centimetres of solution of oxalic acid con- tain 6.3 grammes of the crystallized salt; what weights of bicar- bonate of potassium and anhydrous carbonate of sodium will that volume saturate ? — Ans. 10 grammes and 5.3 grammes. 996. What weight of hydrate of potassium is contained in solution of potash 48.02 grammes of which are saturated by 50 c. c. of the standard solution of oxalic acid? — A7is. 5.83 per cent. 997. State the percentage of hydrate of calcium in lime-water 438 grammes of which are neutralized by 20 c. c. of the volumetric solution of oxalic acid. — Ans. .1689. 998. Eight grammes of a sample of Rochelle salt, after appropriate treatment, require 54.3 c. c. of the oxalic acid solution for complete saturation ; what is the centesimal proportion of real salt present ? — Ans. 95.7. ESTIMATION OF ACIDS. In the previous experiments a known amount of an acid has been used in determining unknown amounts of alkalies. In those about to be described a known amount of an alkali is employed in estimat- ing unknown amounts of acids. The alkaline salt selected may be a hydrate or a carbonate ; but the former is to be preferred ; for the carbonic acid, set free when a strong acid is added to a carbonate, interferes to some extent with the indications of alkalinity, acidity, or neutrality afforded by litmus. The alkali most convenient for use is soda, a solution of which has probably already been made the sub- ject of experiment in operations with the standard solution of oxalic acid. It should be kept in a stoppered bottle and exposed to air as little as possible. Standard Solution of Soda. (Hydrate of Sodium, NaHO = 40.) 100 c. c. of the standard solution of oxalic acid are placed in a beaker with a little litmus, the tube or burette 484 QUANTITATIVE ANALYSIS. in which the acid was measured rinsed out, and the wash- ings poured into the beaker. A little strong solution of caustic soda is poured through the burette to rinse out water adhering to the tube and float (these rinsings thrown away), and the tube then filled to 0 with more of the alka- line liquid. The solution of soda is cautiously allowed to flow into the beaker until exact neutrality is obtained, the quantity noted, and, to every similar quantity of the whole bulk of the solution of soda, water added until the liquid measures 100 parts. If, for example, 93 c. c. of solution of soda have neutralized the 100 c. c. of acid, then 7 c. c. of distilled water must be added to 93 c. c. of the soda solu- tion, or 70 to 930 to make a litre. A sum of simple pro- portion will show to what extent any other quantity is to be diluted. Thus, if the bulk of soda solution remaining measures, say, 900 c. c., its volume must be augmented to 967.7 c. c. ; for if 93 are to be diluted to 100, 900 must be diluted to 967.7. 100 c. c. of the soda solution contain of the molecular weight (= 4), taken in grammes, of pure hydrate of sodium, and will neutralize an equivalent quantity of any acid. That is, 100 c. c. will neutralize of the molecular weight in grammes of an acid containing one atom of any univ- alent acidulous radical, of the molecular weight in grammes of an acid containing one atom of an}^ bivalent acidulous radical, or of the molecular weight in grammes of an acid containing one atom of any trivalent acidulous radical. The following official acids are tested with this solution : — Grammes C. c. of of substance. vol. sol. Acid, acetic 18.20 = 100.0 “ “ diluted, B. P. and U. S. P. 70.29 = 50.0 “ glacial 6.00 = 99.0 “ citric, B. P. and U. S. P. . . . 7.00 = 100.0 “ hydrochloric, B. P. and U. S. P. 11.48 = 100.0 ‘‘ diluted .... 34.50 = 100.0 ‘‘ nitric, B. P. and U. S. P. . . . 9.00 = 100.0 “ “ diluted 36.13 = 100.0 “ nitro-hydrochloric, diluted . . . 38.30 = 100.0 “ sulphuric, B. P. and U. S. P. . 5.06 = 100.0 “ “ aromatic 36.65 = 100.0 “ “ diluted 35.90 == 100.0 “ tartaric, B. P. and U. S. P. . . 7.50 = 100.0 Notes, — 1. In volumetricall}^ estimating the strength of acids by an alkali, the indicator of neutrality is the same as that used in testing alkalies by an acid, namel}^ litmus. VOLUMETRIC ESTIMATION OP ACIDS. 485 2. Pure acetates, citrates, tartrates, and some other or- ganic salts have an alkaline action on litmus, but not to an important extent. If the soda solution be added to acetic, citric, or tartaric acids, containing litmus, until the liquid is fairly blue, the operator will obtain trustworthy results. In delicate experiments turmeric may be used instead of litmus. 3. Six grammes of pure glacial acetic acid are neutra- lized by 100 c. c. of the standard solution of soda. But acid of this degree of purity is extremely difficult to pre- pare. The commercial acid contains only 1 per cent, of water, and is sufficiently pure for use in medicine. Acidimetry . — The operations for the quantitative analysis or measurement of acids are often collectively spoken of under the name of acidimetry. They admit of considerable extension. (See the work previously cited.) Percentage strength of Acids . — The percentage strength of the several acids and their official solutions is readily ascertained by calculation in a manner similar to that given for alkalies. Thus the volumetric operation with the liquid commonly termed acetic acid is based on the reaction expressed in the following equation : — HC,H302 + NaHO = NaC,H302 + H^O. Acetic acid. Soda. Acetate of sodium. Water. This equation, translated into parts by weight, means that 60 parts (the molecular weight) of true acetic acid are exactly neutralized by 40 parts (the molec. wt.) of soda. Supposing the quantity of “ acetic acid” employed in the experiment to have been that recommended in the Table (18.2 grammes), and that to neutralize it 100 c. c. of the soda solution have been used, and remembering that 100 c. c. of the soda solution contain 4 grammes of soda, it follows that the 18.2 grammes of the liquid called acetic acid contain 6 grammes of real acetic acid; for if 40 (the molec. wt.) of soda neutralize 60 (the molec. wt.) of real acetic acid, 4 will neutralize 6. Lastly, if 18.2 contain 6, 100 will contain 33 ; the so-called acetic acid (really an aqueous solution) contains 33 per cent, of true acetic acid (HC2H3 If the 18.2 grammes have taken, say, 93 instead of 100 c. c., the acid liquid is 7 per cent, weak; in other words, it contains only 30.7 per cent, of real acid ; for (by rule-of-three) if 100 c. c. added to 18.2 grammes indicate 33 per cent., 93 c. c. added to 18.2 grammes indicate 30.7 per cent. The remaining acids react with the alkaline salts in the manner and to the extent indicated by the following formula3 and molecular weights : — H2O -+• 3NaHO 41 '^ 210 120 486 QUANTITATIVE ANALYSIS. HCl + NaHO 36.5 40 H,SO, + 2NaHO 98 80 HNO, NaHO 63 40 H.C.H.Og + 2NaHO 150 80 QUESTIONS AND EXERCISES. 999. What percentage of real acid is present in diluted sulphuric acid 30 grammes of which are neutralized by 84 c. c. of the official volumetric solution of soda ? — Ans. 13.72. 1000. How much real nitric acid is contained in a solution 36 grammes of which are saturated by 94 c. c. of the standard solution of soda ? — Ans. 16.45 per cent. ESTIMATION OF ACIDULOUS RADICALS PRECIPI- TATED BY NITRATE OF SILVER. The purity of many salts, and the strength of their solutions, may be determined by this process ; but at present only three official substances (namely, diluted hydrocyanic acid, bromide of potassium, and arseniate of sodium) are quantitatively analyzed by standard solution of nitrate of silver. The reactions on which the success of the process depends are expressed in the following equations : — f AgNO^-f 2Na0y=NaCyAgCy+NaN03, I NaCyAgCy-4-AgN03=2AgCy+NaN03; KBr+ AgN03=AgBr+KN03 ; Na,HAs0,+3AgN03=Ag3As0,4-2NaN03+HN03. Standard Solution of Nitrate of Silver. (Nitrate of Silver, AgN 03 = 170.) Dissolve 17 grammes of crj^stals of pure nitrate of silver in 1 litre of water. 100 c. c. of this solution contain of the molecular weight in grammes of nitrate of silver, and will decompose an equivalent quantity of a salt of any acidulous radical yielding silver compounds insoluble in water. Grammes C. c. of of substance, vol. sol. Acid, hydrocyanic, diluted, B. P. and U. S. P. 27.00 = 100.0 Potassium, bromide of, B. P. and U. S. P. . 1.19 = 100.0 Sodium, arseniate of (dry) 62 = 100.0 VOLUMETRIC ESTIMATION OF ACIDS. 487 Diluted hydrocijanic acid is converted into cyanide of sodium by adding caustic soda until, after stirring, litmus shows that the liquid has an alkaline reaction. The nitrate- of-silver solution is then allowed to flow in gradually, until, after thorough agitation, a slight permanent turbidity re- mains. When this occurs, the quantity of nitrate of silver added represents exactly half the amount of real hydrocy- anic acid present in the diluted preparation. Thus the 100 c. c. of standard solution contains molecular weight, in grammes, of nitrate of silver (= 1.7) ; this would ordinarilj^ correspond, in a case of complete decomposition, to of the molecular weight in grammes of hydrocyanic acid (= .27) ; 27 grammes of the diluted acid, the quantity employed in the experiment, apparently contain therefore .27 grammes of real acid, equal to 1 per cent. A glance at the equation shows that at the moment cyanide of silver begins to be precipitated, only half of the cyanogen has been converted into cyanide of silver ; the quantity of acid indicated by the amount of nitrate added must therefore be doubled for the correct percentage (= 2). 2HNC eq. to AgNOg 54 170 Bromide of potassium is dissolved in distilled water in a beaker, and the standard solution added until, after agita- tion of the liquid and subsidence of the bromide of silver, a drop of the solution of nitrate of silver gives no more precipitate. KBr + AgNOg 119 170 Arseniate of sodium (Na2HAsO^,7H^O) must be dried at 300° F. before weighing. It is thus reduced to a definite anhydrous salt (Na 2 HAsOj, losing, if pure, 40.38 per cent, of water. Of the weighed residue .62 gramme is dissolved in distilled water, 3.3 c. c. of the vol. sol. of soda added, and the whole treated as described in the previous paragraph. Na2HAs0,-fNaH0-f3AgN03=Ag3As0, + 3NaN03 4-H.p Spirit of Wine {Spiritus Rectificatus, B. P.) may contain traces of ainylic alcohol and aldehyd ; these may be detected by nitrate of silver, which is reduced by them to the metallic state. Any quantity beyond a mere trace of such bodies renders spirit of wine too impure 488 QUANTITATIVE ANALYSIS. for use in medicine. ‘‘ Four fluidounces with thirty grain-measures (about two cub. cent.) of the volumetric solution of nitrate of silver exposed for twenty-four hours to bright light, and then decanted from the black powder which has formed, undergoes no further change when again exposed to light with more of the test.” QUESTIONS AND EXERCISES. 1001. Explain the volumetric method of estimating the strength of aqueous solutions of hydrocyanic acid. 1002. How much nitrate of silver will indicate, by the official volumetric process, the presence of I part of real hydrocyanic acid ? — Ans. 3.148 parts. ESTIMATION OE SUBSTANCES READILY OXIDIZED. Any deoxidizer, that is, any substance which quickly absorbs a definite amount of oxygen or is susceptible of any equivalent action, may be quantitatively tested by ascertaining how much of an oxi- dizing agent of known power must be added to a given quantity ; before complete oxidation is effected. The oxidizing agents employed for this purpose in the British Pharmacopoeia are iodine and the red chromate of potassium ; permanganate of potassium is often used for the same purpose. Iodine acts indirectly, by taking hydrogen from water and liberating oxygen ; the red chromate of potassium i directly, by the facility with which it yields three-sevenths of its oxy- i gen — as indicated by the equations and statements given on page j 491 ; permanganate of potassium by affording five-eighths of its I oxygen in presence of acid, 2 K^Mn ^08 + GH^SO^ = 2 K 2 SO 4 -h 4MnS04 + 6H20+502. Standard Solution of Iodine. (Iodine, I = I2Y.) Prepare pure iodine by mixing the commercial article ; with about a fourth of its weight of iodide of potassium and subliming. Sublimation may be effected by gently warming the mixture in a beaker, the mouth of which is closed by a funnel ; the iodine vapor condenses on the funnel; wdiile fixed impurities are left behind, and any chlorine which the iodine may contain is absorbed by the ( iodide of potassium, an equivalent quantity of iodine being | liberated. Small quantities may be similarly treated be- t^veen two watch-glasses, placed edge to edge. Any trace of moisture in the resublimed iodine is removed b}^ ex- I VOLUMETRIC ESTIMATION OF DEOXIDIZERS. 489 posure for a few hours under a glass shade near a vessel containing oil of vitriol. Place 12.Y grammes of pure iodine and about 18 grammes of pure iodide of potassium (an aqueous solution of which is the best solvent of iodine ; the salt plays no other part in these operations) in a litre flask, add a small quantity of water, and agitate until the iodine is dissolved, dilute to 1 litre. 100 c. c. of this solution contain of the molecular weight of free iodine in grammes, and, water being present, will cause the oxidation of of the molecular weight of sulphurous acid (H2SO3) in grammes ( = .41), or (=.32) of sulphurous acid gas (SO2), sulphuric acid being formed. 100 c. c. will also oxidize of the molec- ular weight of arsenious acid (HgAsOg) in grammes, or of the molecular weight of common white arsenic (AS2O3) in grammes (=.495), arsenic acid (HgAsOJ being produced. The reactions are expressed in the following equations: — I2+ + + S02::=.2HI+H^S0,. 1^4. H2 O + H3As 03= 2HI + H^AsO,. 2 X 3 - 4 - 5 H 2 O + As 203=4HI 4- SHgAsO^. l2H-2(Na2S2O3,5H2O)=2NaI-fNa2S,Og-fl0H^O. The following official substances are tested with the standard solution of iodine : — Grammes of C c. of sabstance. vol. sol. Acid, solution of sulphurous . . . 3.47 = 100 Arsenic, in mass, B. P. and U. S. P. . . 0.495 = 100 ‘‘ in alkaline sol. {Liq. Arsenicalis) 54.64 == 100 ‘‘ in acid sol. {Liq, Arsen. Hydrochl.) 54.64 = 100 Sodium, hyposulphite of . 2.48 = 100 The solution of sulphurous acid is diluted with three- fourths of a litre of cold water, and the iodine solution added until a slight permanent brown tint is produced, showing the presence of free iodine. A better indication of the termination of the action is afforded by mucilage of starch, which gives a blue color with the slightest trace of iodine. As already stated, 100 c. c. of this volumetric solution contain an amount of free iodine sufficient to cause the oxidation of 2^^ of the molecular weight of either sulphurous acid or sulphurous acid gas. Now 2^0 of the molecular weight of sulphurous acid (II3SO3) in grammes is 0.41 ; if 3.4T grammes of the solution contain 490 QUANTITATIVE ANALYSIS. 0.41 of the acid, 100 of the solution will be found to con- tain 11.8. By a similar calculation the official solution may be shown to contain, or, rather, yield 9.22 per cent, of sulphurous acid gas (SO^). If the sulphurous acid be diluted to a less degree than .04 or .05 per cent., there will be some risk of the sulphuric acid formed being again reduced to sulphurous acid, with liberation of iodine. In delicate experiments the distilled water used for dilution should previously be freed from air by boiling, to prevent the small amount of oxidizing action which dissolved air would exert. H2SO3 eq. to I2 82 254 SO2 eq. to I2 64 254 The solid arsenic is dissolved in boiling water by help of about two grammes of bicarbonate of sodium. When the liquid is quite cold, mucilage of starch is added, and the iodine solution allowed to flow in until, after well stir- ring, a permanent blue color is produced. II^AsOg eq. to I3 126 254 As ,03 eq. to 21^ 198 508 The arsenical solution already containing some carbonate of potassium requires only about one and a half gramme of bicarbonate of sodium for neutralization of the arsenious acid. After boiling and cooling, starch and the iodine solution are added as before. The solution of arsenic in dilute hydrochloric acid requires about three grammes of acid carbonate of sodium, if 54 or 55 grammes of solution is the quantity employed. After boiling for a few minutes and cooling, the starch and iodine are added. These arsenical solutions contain .9 per cent, of arsenic. The Hyposulphate of sodium is dissolved in water, starch mucilage added, and the iodine solution slowly run in, the whole being frequently stirred, until a permanent blue color is produced. In the previous reactions iodine has acted as an indirect oxidizing agent by uniting with the hydrogen and thus liberating the oxygen of water. In the present case it unites with an analogue of hydrogen, namely, sodium. VOLUMETRIC ESTIMATION OF DEOXIDIZERS. 491 QUESTIONS AND EXERCISES. 1003. Give equations illustrative of the reactions on which the use of a standard volumetric solution of iodine is based. 1004. From what point of view may iodine be regarded as an oxi- dizing agent ? 1005. What reagent indicates the termination of the reaction be- tween deoxidizing substances and moist iodine ? 1006. How much sulphurous acid gas will cause the absorption of 2.54 parts of iodine in the volumetric reaction ? Ans. .64. 1007. What quantity of iodine will be required, under appropriate conditions, to oxidize 5 parts of arsenic? Ans. 12.828. 1008. Find by calculation the amount of hyposulphite of sodium equivalent to 13 parts of iodine in volumetric analysis. Ans. 25.389. Standard Solution of Red Chromate of Potassium. (Red Chromate of Potassium, K^CrO^, CrO^ = 295.) One molecule of red chromate of potassium in presence of an acid, under favorable circumstances, yields four atoms of oxygen to the hydrogen of the acid, leaving three available either for direct oxida- tion or for combination with the hydrogen of more acid, an equiva- lent proportion of acidulous radical being liberated for any required purpose. When used as a volumetric agent, the red chromate always yields the whole of its oxygen to the hydrogen of the accompanying acid, a corresponding quantity of acidulous radical being set free — four- sevenths of this radical immediately combining with the potassium and chromium of the red chromate, three-sevenths becoming avail- able. Ferrous may thus be converted inta ferric salts with sufficient rapidity and exactitude to admit of the estimation of an unknown quantity of iron by a known quantity of the red chromate. As one atom of the liberated acidulous radical will convert two molecules of ferrous into one of ferric salt, one molecule of red chromate causes six of ferrous to become three of ferric, as shown in either of the fol- lowing equations : — K^CrO,, Cr03+7H2S0,+ 6FeS0,=K2S0,, +3(Fe,3SO,); K.CrO^, Cr03+14HC14- 6FeCl2=2KCH-0r2Cl6+7H,O+3Fe,0l6. These equations indicate that, in presence of excess of acid, 295 parts (the molecular weight) of red chromate of potassium will con- vert 1668 parts of crystallized ferrous sulphate, 6(FeS04,7H20= 278), or an equivalent quantity of ferrous chloride (6FeOl2=762), ferrous carbonate (6FeC03=696), ferrous arseniate (2Fe3As20g= 892), ferrous phosphate (2Fe3P208=716), or iron itself (3Fe2=336), into ferric salt. If these parts be taken in grammes, ^ J ^ or less of the stated amounts will be found to be convenient quantities for experiment. 492 QUANTITATIVE ANALYSIS. Dissolve 1 4. Y 5 grammes of red chromate of potassium in one litre of distilled water. 100 c. c. of this solution con- tain 2^77 of the molecular weight of the salt in grammes, and will cause the conversion of of the weight of 6 atoms of iron in grammes, or an equivalent quantity of the lower salts of iron, from the ferrous to the ferric state. The solution is used in determining the strength of the following official ferrous preparations. It is known that the whole of the ferrous has been converted to ferric salt when a small drop of the liquid- placed in contact with a drop of a very dilute solution of ferridcyanide of potas- sium, on a white plate, ceases to strike a blue color. Grammes of C. c. of substance. v*ol. sol. Iron, , arseniate of . . 2.94 - 25 u magnetic oxide of ... . . . 2.41 = 10 phosphate of, B. P. and U. ^ :;.P . 2.00 = 25 u saccharated carbonate of . . . 4.70 = 50 The several compounds are dissolved in excess of hydro- chloric acid diluted with water, and the standard solution then dropped in. The ferrous liquid must not be exposed to the air for more than a few seconds after solution has been effected, or oxygen will be absorbed and a corres- ponding amount of ferric salt formed before the volumetric oxidizing agent is added: in most cases diluted sulphuric acid may be used as a solvent of the ferrous salt, ferrous sulphate absorbing oxygen from the air far less rapidly than ferrous chloride. It will be found that the propor- tion of carbonate of iron in the saccharated compound, as indicated by the above numbers, is, 3Y in 100. Trade samples yield from 20 to 30, and sometimes 35 per cent., according to the care with which oxidation has been pre- vented. The theoretical percentage obtainable from the ingredients is 45.5, the quantit}^ that would be present if the compound were anhydrous and unox 3 "dized, conditions never obtained in practice. The 2 grammes of phosphate of iron should contain .895 of real ferrous phosphate or nearly 45 per cent. The use of these two volumetric solutions in quantita- tive analj'sis admits of great extension. VOLUMETRIC ESTIMATION OF OXIDIZERS. 493 QUESTIONS AND EXERCISES. 1009. Write equations explanatory of the oxidizing power of red chromate of potassium. 1010. One hundred cubic centimetres of an aqueous solution of red chromate of potassium contain of the molecular weight of the salt in grammes ; what weight of metallic iron, dissolved in hydro- chloric acid, will this volume oxidize ? — Ans. 1.68 gramme. 1011. If 8.34 grammes of a specimen of crystallized ferrous sul- phate require 93 c. c. of the standard solution of chromate for com- plete oxidation, what percentage of real salt is present ? — Ans. 93. 1012. How much red chromate of potassium is required for the conversion of 10 parts of ferrous sulphate into ferric salt? — Ans. 1.768. 1013. What quantity of pure ferrous carbonate is indicated by 1.475 part of red chromate as applied in volumetric analysis ? — Ans. 3.48. 1014. State the amount of official saccharated carbonate of iron equivalent to .7375 part of red chromate in the volumetric reaction. — Alts. 4.7. ESTIMATION OF SUBSTANCES READILY DEOXIDIZED. Any substance which quickly yields a definite amount of oxygen may be quantitatively tested by ascertaining how much of a deoxi- dizing agent of known power must be added to a given quantity be- fore complete deoxidation is effected. The chief compounds which may be used as absorbers of oxygen (deoxidizers oi* reducing agents, as they are commonly termed) are hyposulphite.of sodium, sulphurous acid, ferrous sulphate,* oxalic acid, arsenious acid. The first-named is officially employed ; it is only used in the estimation of free iodine, and, indirectly, of chlorine and chlorinated compounds. Iodine and chlorine are regarded as oxidizing agents, because their great affinity for hydrogen enables them to become powerful indirect oxidizers in presence of water. Standard Solution of Hyposulphite of Sodium. (Crystallized Hyposulpliiteof Sodium, Na 2 S 203 , 5 H 20 = 248.) Dissolve about 30 grammes of h^^posulpliite of sodium in a litre or less of water. Fill a burette with this solu- tion, and allow it to flow into a beaker containing exactly 100 c. c. of the volumetric solution of iodine until the brown color of the iodine is just discharged — or, starch * “Five grains of Permanganate of Potassium dissolved in water require for decoloration a solution of forty-four grains of granulated sulphate of iron acidulated with two fluidrachms of diluted sulphuric acid.” — B. P. 42 494 QUANTITATIVE ANALYSIS. being added, until the blue iodide of starch is decolorized. Note the number of c. c. of hyposulphite solution required, and to the bulk of the solution add water, so that 2.48 grammes of hyposulphite of sodium shall be contained in every 100 c. c. When iodine and hyposulphite of sodium react, two atoms of iodine remove two of sodium from two molecules of the hyposulphite, tetrathionate of sodium being formed, as indicated in the following equation : — 1 , 4- 2 Na 2 S ,03 = 2NaI + Na.S.Og. As, therefore, 100 c. c. of the iodine solution contain of the atomic weight of iodine in grammes, 100 c. c. of the standard solution of hyposulphite of sodium will contain yiiy of the molecular weight of the salt in grammes, and will show the existence of of the atomic weight of iodine in grammes in any quantity of a liquid nor- mally containing free iodine, or iodine liberated by an equivalent quantity of free chlorine. This solution is employed for quantitatively testing the following substances : — Chlorine, solution of ... . Grammes of substance. . . 29.26 = C. c. of vol. sol. 50 Iodine, B. P. and U. S. P. . . . . 1.27 = 100 Lime, chlorinated . . 1.17 - 100 solution of chlorinated . . . 6.00 = 50 Soda, solution of chlorinated ,. . . 7.00 = 50 2^ote . — Owing to the volatility of chlorine and iodine, and the readiness with w^hich they attack the metals of which balances are made, it is not desirable to experiment on stated weights of substances containing these elements. A small stoppered bottle or tube containing the material may be counterpoised, and a convenient quantity removed for analysis, the precise amount taken being ascertained by again weighing the bottle. The iodine may be dissolved in water containing about a gramme and a half of iodide of potassium, a salt giving no reaction with hyposulphite of sodium. I2 eq. to 2(Na2S203,6H20) 254 496 It is assumed in this operation that the iodine has been | shown by qualitative analysis to be free from chlorine and | bromine. These elements resemble iodine in reacting with I VOLUMETRIC ESTIMATION OF OXIDIZERS. 495 hyposulphite of sodium, hence would reckon as iodine in a volumetric assay. The solution of chlorine is added to water containing ex- cess of iodide of potassium (about a gramme and a third); a quantity of iodine, equivalent to the amount of chlorine present, is thus liberated. The hyposulphite solution is then dropped in. Cl, eq. to 2 (Na,S, 03 , 5H,0) ' — ' V ' n 496 The chlorinated lime (“chloride of lime” or “bleaching- pow^der”) is mixed with about a fifth of a litre of water containing excess of iodide of potassium (3.5 grms.) and acidulated with hydrochloric acid. The available oxygen of the chlorinated lime liberates chlorine from an equivalent quantity of hydrochloric acid ; and this, with the available chlorine of the chlorinated lime, sets free an equivalent amount of iodine from the iodide of potassium. The hypo- sulphite and iodine reacting show the direct and indirect oxidizing power of the chlorinated lime; it should corre- spond to 30 per cent, of chlorine. For example, as 248 (1 molecule) of hyposulphite indicate the presence of 35.5 (1 atom) of chlorine, 2.48 of h3q30sulphite (the quantity in 100 c. c.) indicate the presence of .355 of chlorine. If 100 c. c. have been used, therefore, .355 of chlorine is obtainable from the quantity of bleaching-powder employed (1.1 T). And if 1.1 'Z of bleaching-powder yield .355 of chlorine, 100 will yield about 30 (30|- nearly). The solution of chlorinated lime is mixed with about a fifth of a litre of water containing a couple of grammes of iodide of potassium, and ten or twelve c. c. of hydrochloric acid. The hyposulphite solution is then added from a burette until the color of the liberated iodine is just dis- charged. The solution of chlorinated soda is similarly treated. Note. — 1. In these experiments the blue color formed on the addition of mucilage of starch to the liquids will be found to be a more delicate indicator of the termination of i reactions than the brown tint of the iodine. Note. — 2. Standard solutions used in volumetric analysis are often described as normal, decinormal, and centinormal. A normal solu- tion (N) contains in every litre the molecular weight of the salt, talcenin grammes; a decinormal solution is one-tenth (/j), and a I centinormal (1^5) one-hundredth the strength of such a normal solu- ' tion. 496 QUANTITATIVE ANALYSIS. QUESTIONS AND EXERCISES. 1015. For what purposes is the official volumetric solution of hypo- sulphite of sodium used ? 1016. On what reaction is based the quantitative employment of hyposulphite of sodium? 1017. How much hyposulphite of sodium is required to show the presence of 10 parts of iodine ? — Ans. 19.527. 1018. To what amount of chlorine is 4.96 parts of hyposulphite of sodium equivalent in volumetric analysis? — Ans. 0.71. 1019. Describe the operations included in the estimation of the strength of bleaching-powder. 1020. By what reagent is the complete absorption of free iodine by hyposulphite of sodium indicated? MISCELLANEOUS PROBLEMS. 1021. How much bicarbonate of potassium is contained in an eight-ounce bottle of medicine, seven fluidrachms of which are satu- rated by two and a half grains of crystallized oxalic acid ? — Ans. 18.1 grains. 1022. A sample of soda-ash is said to contain 78 per cent, of pure anhydrous carbonate of sodium ; if the statement is true, how much of the official volumetric solution of oxalic acid will saturate 5 grammes of the specimen ? — Ans. 73.6. 1023. 2.69 grammes of common brown sulphuric acid are saturated by 43.5 cubic centimetres of the official volumetric solution of soda ; how much acid of 96.8 per cent, is present? — Ans. The 2.69 con- tain 2.2. 1024. Four grammes of a litre and a half of concentrated hydro- cyanic acid are neutralized by 89 cubic centimetres of volumetric solution of nitrate of silver of official strength ; to what volume must the bulk of the acid be diluted for the production of acid of pharma- copoeia! strength ? — Ans. 9 litres. 1025. 3.18 grammes of a pow’der containing arsenic require for complete reaction 84 cubic centimetres of a volumetric solution of iodine, which is 1.43 weaker than the standard solution of the British Pharmacopoeia ; what percentage of pure arsenic is contained in the pow'der ? — Ans. 12.86. 1026. Ho\v much pure metal is present in a sample of iron 1.68 gramme of which dissolved in dilute sulphuric acid, is exactly attacked by 95.7 cubic centimetres of a semi-decinornial volumetric solution of red chromate of potassium which is 6 per cent, too strong ? GRAVIMETRIC ESTIMATION OF POTASSIUM, 497 GRAVIMETRIC ANALYSIS. ESTIMATION OF METALS. POTASSIUM. Outline of the Process . — This element is usually estimated in the form of double chloride of potassium and platinum. Qualitative analysis having proved the presence of potassium and other ele- ments in a substance, a small quantity of the material is accurately weighed, dissolved, and the other elements removed by appropriate reagents ; the precipitates are well washed, in order that no trace of the potassium salt shall be lost, the resulting liquid concentrated over a water-bath (to avoid loss that would occur mechanically during ebullition), hydrochloric acid added if necessary, solution of perchloride of platinum poured in, and evaporation continued to dryness ; excess of the perchloride is then dissolved by adding spirit of wine containing half its bulk of ether (a liquid in which the double chloride is insoluble), the mixture carefully poured on to a tared and dried filter, washed with the spirit till every trace of free per- chloride of platinum is removed, the whole dried and weighed ; from the resulting amount the proportion of potassium, or equivalent quantity of a salt of potassium, is ascertained by calculation. Note . — From this short description it will be seen, first, that the chemistry of quantitative is the same as that of qualitative analysis ; the second, that the principle of gravimetric is the same as that of volumetric quantitative analysis — the combining- proportions being known, unknown quantities of elements may be ascertained by calculation from known quantities of their compounds. Apjpo^ratus . — In addition to a delicate balance and weights and the common utensils, a few special instru- ments are used in quantitative manipulation ; some of these may be prepared before proceeding with the estima- tion of potassium. Filtering-paper may be of the kind known as ‘‘ Swedish,’^ the texture of which is of the requisite degree of closeness, and its ash small in amount. A large number of circular pieces of one size, six to eight centimetres in diameter, should be cut ready for use. In delicate experiments, where a precipitate on a filter has to be heated and the paper consequently burnt, the weight of the ash of the filter must be deducted from the weight of the residue. The ash is estimated by burning ten or twenty of the cut filters. These are folded into a small compass, a portion 42 * 498 QUANTITATIVE ANALYSIS. of a piece of platinum wire twisted a few times round the packet, so as to form a cage, the whole held by the free end of the wire over a w eighed porcelain crucible placed in the centre of a sheet of glazed paper, the bundle ignited by a spirit-lamp or smokeless gas-flame, the flame allowed to impinge against the charged mass till it falls into the crucible below, any stray fragments on the sheet carefully shaken into the crucible, the latter placed over a flame till carbon has all burnt off and nothing but ash remains, the whole cooled, weighed, and the weight of the crucible de- ducted; the weight of the residue divided by the number of pieces used gives the average amount of ash in each filter. A pair of Weighing-tubes^ for holding dried filters during operations at the balance,ma 3 " be made from two test-tubes, one fitting closely' within the other. About five centimetres of the closed end of the outer and seven of the inner are cut off, hy leading a crack round the tube with a pencil of incandescent charcoal, and the sharp edges fused in the blowpipe-flame. A filter, after drying, is quicklj^ folded and placed in the narrower tube, the mouth of which is then closed by the wider tube. This prevents reabsorption of moisture from the air. The Washing-bottle the spirit of wine and ether ^ is a common bottle, through the cork of which a short straight tube passes. The outer end of the tube should be sufficiently narrowed to enable it to deliver a ver}" fine stream of the liquid. The bottle being inverted, the w^armth of the hand expands the air and vapor to a sufficient ex- tent to force out the liquid. The Ordinary Washing-bottle for quantitative operations should be formed of a flask in which water may be boiled, fitted up as usual {vide p. 93). A Water-oven is the best form of drying-apparatus. It is a small square copper vessel, jacketed on five sides and having a door on the sixth ; water is poured into the space between the inner and outer casing, and the whole placed over a gas-lamp or source of heat, moist air and steam escaping by appropriate apertures. Desiccation at higher temperatures than the boiling-point of water may be prac- tised by using oil or paraffin instead of water, inserting a thermome- ter in the fat. The apparatus may be purchased of any maker of chemical instruments. Pure distilled water must be used in all quantitative determina- tions. Note. — In practising the operations of quantitative analysis, experiments should at first be conducted on definite salts of known composition, for the accuracy of results may then be tested by calculation. GRAVIMETRIC ESTIMATION OF POTASSIUM. 499 Estimation of Potassium in the form of double chloride of potassium and platimim, — Select two or three crystals of pure nitrate of potassium, powder them in a clean mortar, dry the powder by gently heating in a porcelain crucible over a flame for a few seconds, place about a couple of decigrammes (0.2 grm.) of the powder in a counterpoised watch-glass, accurately weigh the selected quantity, trans- fer to a small dish, letting water from a wash-bottle flow over the watch-glass and run into the dish, warm the dish till the nitrate is dissolved, acidulate with hydrochloric acid, add excess of .aqueous solution of perchloride of pla- tinum (a quantity containing about 0.4 of solid salt), evaporate to dryness over a water-bath. While evapora- tion is going on, place a filter and the weighing-tubes in the water-oven, exposing them to a temperature of 212° F. for about half an hour ; fold the filter and insert it in the tubes, place them on a plate under a glass shade, and when cold accurately note their weight. Arrange the weighed filter in a funnel over a beaker. Transfer the dried and cooled platinum salt from the dish to the filter by moistening the residue with the mixture of alcohol and ether, and, when the salt is loosened, pouring the contents of the dish into the paper cone. Any salt still adhering may be freed by the finger, which, together with the dish, should be washed in the stream of spirit, the rinsings at once flowing into the filter. The filtrate should have a yellowish-brown color, due to the excess of perchloride of platinum. If it is colorless, an insufficient amount of perchloride has been added, and the whole operation must be repeated. The washed precipitate and filter are finally dried in the water- oven, folded and placed in the v^eighing-tubes, the drying continued until the whole, after repeated weighing when cold, ceases to alter; the final weight is noted. Note . — If filters are not freed from all trace of acid by thorough washing, the paper will be brittle when dry, falling to pieces on being folded. Analytical memoranda in the note book may have the following form: — Watch-glass and substance .... Watch-glass Substance . . Weighing-tubes, filter, and Pt salt . . Weighing-tubes and filter PtCI,,2KCl. . . 500 QUANTITATIVE ANALYSIS. The calculations are simple: — |I tW,^2KCl| equivalent to i the weight of ^ double chloride >• is equivalent to x. x will be the obtained ) amount of pure nitrate of potassium in the quantity of sub- stance operated on. x should, in the present instance, be identical with the weight of substance taken, because, for educational purposes, pure nitre is undei-examination. Only after analyses of pure substances have yielded the operator results identical with those by calculation, can analyses of substances of unknown degree of purity be undertaken with confidence. A table of atomic weights, from which to find molecular weights, is given in the Appendix. A Water-bath for the evaporation of liquids or for drying moist solids at temperatures below 212^ F. is an iron, tin, or earthenware pan, the mouth of w^hich can be narrowed by iron or tin diaphragms of various sizes and having orifices adapted to the diameters of evaporating-dishes or plates. In the British Pharmacopoeia, “ when a loater-bath is directed to be used, it is to be understood that this term refers to an apparatus by means of which water or its vapor, at a temperature not exceeding 2120. jg applied to the outer surface of a vessel containing the substance to be heated, which substance may thus be subjected to a heat near to, but necessarily below, that of 2120. In the steam-bath the vapor of water at a temperature above 2120, i^at not exceeding 230O, is similarly applied.” Evaporation in vacuo is performed by simply placing the vessel of liquid over or by the side of a small reservoir of strong sulphuric acid or other absorbent of moisture, on the plate of an air-pump, covering with a capacious receiver, and exhausting. Platinum residues should be preserved, and the metal recovered from them from time to time [vide p. 221). Hot alcohol sometimes reduces perchloride of platinum, the metal being thrown out of solution in a finely divided form, known plati- num black ; only aqueous solutions, therefore, of the salt should be used where heat is employed. Hence, also, in washing out excess of perchloride of platinum from the double chloride of platinum and potassium by spirit, the application of heat should be avoided. Effervescing Potasli-ivater [Liquor Potassce Effervescens, B.P.) is most easily estimated volumetrically (p. 481). Any adulteration by an equivalent amount of bicarbonate of sodium would, however, by that process be undetected ; hence the Pharmacopoeia directs that “ five fluidounces, evaporated to one-fifth, and r2 grains of tar- taric acid added, yield a crystalline precipitate, which, when dried, weighs not less than 12 grains.” Five fluidounces of this prepara- tion should contain 7.5 grains of bicarbonate, convertible into 14.1 GRAVIMETRIC ESTIMATION OP SODIUM. 501 grains of acid tartrate of potassium by 11.25 grains of tartaric acid. The method is somewhat rough, but quite efficient for “ potash-water” containing nothing but bicarbonate of potassium. Proportional weights of equivalent quantities of potassium and its salts. Metal K, . 78 Oxide (“ potash’^) . . . . K ,0 .... . 94 Hydrate (“caustic potash’’) 2 KHO .... . 112 Carbonate (anhydrous) . K^CO,. . . . . 138 Carbonate (crystalline) . . K,CO,+16% aq. . 164.285 Bicarbonate 2 KHC 63 . . . . 200 Nitrate 2 KNO 3 .... . 202 Platinum salt PtCl,, 2KCI . . . 489 SODIUM. Sodium is usually estimated as sulphate. Accurately weigh a porcelain crucible and lid, place within about .3 of pure rock-salt, and again weigh, making a memorandum of the weights in a note-book. Add rather more strong sulphuric acid than may be considered sufficient to convert the chloride into acid sulphate of sodium. Heat the cru- cible graduall}^, the flame being first directed against the side of the crucible to avoid violent ebullition, until fumes of acid cease to be evolved, towards the end of the operation dropping in one or two fragments of carbonate of ammonium to facilitate complete expulsion of all excess of acid. When cold, weigh the crucible and contents. The weight of the crucible having been deducted, the amount of sulphate obtained should be the exact equivalent of the quantity of chloride of sodium employed. 2 NaCl + H,SO, = Na^SO, -f 2HC1. Ill 142 Proportional weights of equivalent quantities of sodium and its salts. Metal . Na, 46 Oxide (“ soda”) , Na,0 .... 62 Hydrate (“ caustic soda”) . . , . 2 NaHO . . . 80 Carbonate (anh 3 ^drous) . . . , . Na 3 C 03 . . . 106 Carbonate (cr^-stals) . . . . , . Na,CO„ 10 H^O . 286 Bicarbonate . 2 NaHC 03 . . 168 Chloride . 2NaCl .... in Sulphate (anh 3 ^drous) .... . Na^SO, . . . 142 Sulphate (crystals) . Na^SO^lOH^O . 322 502 QUANTITATIVE ANALYSIS. AMMONIUM. Salts of ammonium are, for purposes of quantitative analysis, generally converted into the double chloride of ammonium and platinum (PtCl 42 NH^Cl), the details of manipulation being the same as those observed in the case of potassium. About 0.15 grm. of pure, white, dry chlo- ride of ammonium may be taken for experiment. COMPOSITION OF THE PLATINUM SALT. In 1 molecule. In 100 parts. Ft . . . 198 . . 198 . . . 44.30 Cls . . . 35.5 X 6 . . . 213 . . . 47.64 N, . . . 14.0 X 2 . . . 28 . . . 6.27 Hs . . 1.0 X 8 . 8 . . . 1.79 447 100.00 PtCl, . , . 340 . . 340 . . . 76.06 2NH,C1 . 53.5 X 2 . . . 107 . . . 23.94 447 100.00 The proportion of nitrogen, ammonium, or chloride of ammonium in the double chloride may also be ascertained from the Tveight of platinum left on igniting the double chloride; for this purpose heat must be applied slowly, or platinum will be mechanically carried otf with the gas- eous products of decomposition Proportional weights of equivalent quantities of ammoniac al compounds. Ammonia (gas) . 2NH, .... . 34 Ammonium . (NHJ,? . . . . 36 Chloride of ammonium . . . 2NH,C1 . . . . 107 Platinum salt . PtCl,,2NH,Cl . . 447 Carbonate of ammonium^^ . (NJI.,C,OJ - 2 . 118 Sulphate of ammonium . . . (NH,),SO, . . . 132 BARIUM. Barium is estimated in the form of anhydrous sulphate of barium (BaSOJ. Process . — Dissolve 0.3 or 0.4 of pure crystallized and dried chloride or nitrate of barium in about half a litre of water in a beaker, heating to incipient ebullition, and slightly acidulating with hydrochloric or nitric acid. Add GRAVIMETRIC ESTIMATION OF BARIUM. 503 diluted sulphuric acid (prepared some days previously, so that sulphate of lead may have deposited) so long as a precipitate forms, keep the mixture hot for some time, set aside for half an hour, pass the supernatant liquid through a filter, gently boil the residue two or three times with more water; finally collect the precipitate on the filter, removing adherent particles from the beaker by the finger, and cleansing by a stream of hot water from the wash- bottle. The precipitate must be washed with hot water until the filtrate ceases to turn litmus paper red, or give any cloudiness when tested with chloride of barium. The filter and sulphate of barium, having thoroughly drained, is dried in a warm place, commonly by supporting the funnel in an inverted bottomless beaker over a sand-bath or hot plate. The sulphate of barium is now removed from the filter, heated to drive off* every trace of moisture, and weighed. This is accomplished by placing a weighed porcelain cru- cible (and cover) on a sheet of glazed paper, holding the filter over it, and carefully transferring the precipitate ; the sides of the filter are then gently rubbed together and detached powder dropped into the crucible, the paper folded, encased in two or three coils of one end of a plati- num wire and burnt over the crucible, ash and any particles in the sheet of paper dropped into the sulphate of barium, the open crucible exposed over a fiame till its contents are quite white, covered, cooled, and weighed. Formulae. Molecular weights. Chloride of barium . . BaCl, . . . 208 Nitrate of barium . • . • . Ba 2 N 03 . 261 Sulphate of barium . . . . . BaSO, . . 233 Composition of Sulphate of Barium. In one In 100 molecule. parts. Ba 131 . . . . 131 . . 68.80 S 32 . . . . 32 . . 13.73 0. 16x4. . . 64 . . 27.47 233 100.00 In these experiments it is unnecessary to take filter-ash into account. Faults of manipulation cause far greater errors. 504 QUANTITATIVE ANALYSIS. CALCIUM. Calcium is usually thrown out of solution in the form of oxalate, the precipitate ignited, and the resulting carbonate w^eighed. Process, — Dissolve 0.3 or 0.4 of dried colorless crystals of calc-spar in about a third of a litre of water acidulated with h^uirochloric acid, heat the solution to near the boil- ing-point, add excess of solution of oxalate of ammonia, then ammonia until, after stirring, the liquid smells strongly ammoniacal; set aside in a warm place for twelve hours. Carefully pour off the supernatant liquid, passing it through a filter ; add hot water to the precipitate, set aside for half an hour, again decant, and, after once more washing, trans- fer the precipitate to the filter, allowing all contained fluid to pass through before a fresh portion is added. Wash the precipitate with hot water, avoiding a rapid stream, or the precipitate may be driven through the pores of the I paper. Diy, transfer to a weighed crucible, and incinerate, | as described for sulphate of barium, and slowlj^ heat the i precipitate till the bottom of the crucible is just visibly red when seen in the dark. As soon as the residue is white, | or only faintly gray, remove the lamp, cool, and weigh. The resulting carbonate of calcium should have the same weight as the calc-spar from which it was obtained. If loss has occurred, carbonic acid gas has probably escaped. . In that case moisten the residue with water, and after a 1 few minutes test the liquid with red litmus or turmeric paper; if an alkaline reaction is noticed, it is due to the presence of caustic lime. Add a small lump of carbonate of ammonium, evaporate to diyness over a water-bath, and again ignite, this time being careful not to go beyond the prescribed temperature. The treatment may, if necessary, ^ be repeated. Proportional weights of equivalent quantities of calcium salts. Oxide (quicklime) CaO 56 Hydrate (slaked) lime . . . . . Ca2HO .... 74 ' Carbonate CaCOg . . . . 100 Sulphate (anlij^drous) CaSO^ . . . . 136 il Sulphate (crystalline or precipCd) . CaSO., 2 H 2 O . .172 ^ Chloride CaCl^ .... Ill ' Phosphate (of bone) (Cag2POJ310 -r 3 103.3 •: Superphosphate CaH^2PO^ . . . 234 N GRAVIMETRIC ESTIMATION OF MAGNESIUM. 505 MAGNESIUM. Process 1. — The light or heavy carbonate of magnesium of pliaraiacj^ may be estimated by heating a weighed quan- tity to redness in a porcelain crucible. If it has the com- position indicated by the formula given in the British Pharmacopoeia (SMgCO.^, Mg2HO,4H.^O), it will 3deld 42 per cent, of magnesia (MgO). According to that work, the purity of even sulphate of magnesium (MgSO^, may be determined by boiling a weighed quantity with excess of carbonate of sodium, collecting the precipitate, washing, dr^dng, igniting, and weighing the resulting mag- nesia (MgO). The crystallized sulphate should afford 16.26 per cent, of oxide. The official solution of carbonate of magnesium in carbonic acid water {Liquor Magnesise Garhonatis^ B. P.) should yield five grains of pure oxide of magnesium per fluidounce. Process 2. — The general form in which magnesium is precipitated is as phosphate of ammonium and magnesium (MgNH^PO^, 6H2O) ; this, by heat, is converted into pyro- phosphate of magnesium (Mg2P20-). Accurately weigh a small quantity (0.4 to 0.5) of pure dry crystals of sulphate of magnesium, dissolve in two or three hundred cubic centimetres of cold water in a beaker, add chloride of am- monium, ammonia, and phosphate of sodium or ammo- nium, agitate with a glass rod (without touching the sides of the vessel, or crystals will firmly adhere to the rubbed portions), and set aside for twelve hours. Collect on a filter, wash the precipitate with water containing a tenth of its volume of the strongest solution of ammonia, until the filtrate ceases to give a precipitate with an acidulated solution of nitrate silver. Dry, transfer to a crucible, burn the filter in the usual way, heat slowly to redness, cool, and weigh. Proportional weights of equivalent quantities of magnesium salts. Pyrophosphate . . Mg^P^O^ 222 Sulphate .... 2(MgS04, TH^O) 492 Oxide 2(MgO) 80 Official carbonate . (3MgCO ., Mg2HO, 41T,.0) 2 . 191 43 506 QUANTITATIVE ANALYSIS. ZINC. Zinc is usually estimated as oxide (ZnO), occasionallj^ as sulphide (ZnS). Process . — Dissolve a weighed quantity (0.5 to 0.6) of sulphate of zinc in about half a litre of water in a beaker, heat to near the boiling-point, add carbonate of sodium in slight excess, boil, set aside for a short time ; pass the supernatant liquid through a filter, gently boil the precipi- tate with more water, again decant ; repeat these opera- tions two or three times ; collect the precipitate on the filter, wash, dry, transfer to a crucible, incinerate, ignite, cool, and weigh. 281 (=molec. weight) of sulphate should yield 81 (=molec. weight) of oxide. MANGANESE. To ascertain its value for evolving chlorine from hydro- chloric acid a weighed quantity of finely powdered black oxide of manganese is heated in a small flask with pure hy- drochloric acid, and the resulting chlorine conveyed into a U-tube containing solution of iodide of potassium. The amount of iodine thus freed is estimated by the volumetric solution of hyposulphite of sodium. 127 of iodine indi- cate 35.5 of chlorine. ALUMINIUM. Aluminium is always precipitated as hydrate (AlgfiHO) and weighed as oxide (AI 2 O 3 ). Process . — Dissolve about two grammes of pure dry am- monium-alum in half a litre of water, heat the solution, add chloride of ammonium and a slight excess of ammonia, boil gently till the odor of ammonia has nearly disap- peared, set aside for the hydrate to deposit, pass the super- natant liquid through a Alter, wash the precipitate three or four times by decantation, transfer to the filter, finish the washing, dry, burn the filter, ignite in a covered cruci- ble, and weigh. Al,3SO„ (NHJ,SO„ 24H^O 907 AI 2 O 3 103 Per cent, of Al^Og yielded by ammonium-alum . 11.356 GRAVIMETRIC ESTIMATION OP IRON. 50t QUESTIONS AND EXERCISES. ' 1027. Give details of the manipulations observed in gravimetrically estimating salts of potassium or ammonium. 1028. What quantity of chloride of sodium is contained in a sample of rock-salt 0.351 gramme of which yields 0.44 of sulphate of sodium ? — Ans. 100 per cent. (It is absolutely pure.) 1029. To what amount of the official alum is 0.894 of a gramme of the double chloride of platinum and ammonium equivalent? — A^is. 1.814 gramme. 1030. Find the weight of sulphate of barium obtainable from 0.522 of nitrate. — Ans. 0.466. 1031. Describe the usual method by which salts of calcium are estimated. 1032. By what quantitative processes may the official salts of magnesium be analyzed ? 1033. Calculate the proportion of pure sulphate of zinc in a sample of crystals 0.574 of which yield 0 161 of oxide — Ans. 99.3 per cent. 1034. Ascertain the weight of alumina (AI^Ojj) which should be obtained from 1.814 gramme of ammonium-alum. IRON. Iron and its salts are gravimetrically estimated in the form of ferric oxide (Fe.^Og). Compounds containing organic acidulous radicals are simply incinerated, and the resulting oxide weighed. Thus 1 gramme of the official citrate of iron and ammonium {Ferri et Ammonise Oitras.^ B. P.) incinerated, with expo- sure to air, leaves not less than .27 of ferric oxide. A small quantity of the salt is weighed in a tared covered porcelain crucible, flame cautiously applied until vapors cease to be evolved, the lid then removed, the crucible slightly inclined and exposed to a red heat until all carbonaceous matter has disappeared. The residual ferric oxide is then weighed. The tartrate of potassium and iron {{Ferrum Tartaratum^ B. P.) is treated in the same manner, except that the ash must be washed and again heated before weighing, in order to remove carbonate of potassium produced during incine- ration ; 5 grammes should 3 deld 1.5 gramme of ferric oxide. From other compounds of iron, soluble in water or acid, the metal is precipitated in the form of hydrate (Fe.^6HO) by solution of ammonia, and converted into oxide (Fe.^Og) by ignition. Dissolve a piece (about 0.2) of the purest iron obtainable (piano wire), accurately weighed, in water 508 QUANTITATIVE ANALYSIS. acidulated with hydrochloric acid ; add a few drops of nitric acid and gently boil ; pour in excess of ammonia, stir, set aside till the ferric hydrate has deposited, pass the supernatant liquid through a filter, treat the precipitate three or four times wdth boiling water ; transfer to the filter, wasli till the filtrate yields no trace of chlorine (for chloride of ammonium will decompose ignited ferric oxide, with volatilization of ferric chloride), dry and ignite as usual, and weigh. Iron in the official solutions {Liquor Ferri Fercliloridi Fortior^ Liquor Ferri Pernitratis^ and Liquor Ferri Persulphatis) may be estimated by this general process. The proportion of metallic iron in a mixture of iron and oxides of iron may be determined by digestion in a strong solution of iodine in iodide of potassium, which attacks the metal only. The reduced iron of pharmacy {Ferrum Bedactum) is in good condition so long as it contains, as show^n by this method, half its weight of free metal. Pi'oportional weights of equivalent quantities of iron and its salts. Metal .Fe, . 112 Ferric oxide . . . • Fe,0, . 160 Ferric hydrate . . . Fe,6HO . . . . . 214 Ferric chloride . . . Fe,Cl, . 325 Ferric sulphate . . . Fe„3SO, . . . . . 400 Ferrous sulphate . . 2(FeSO,, TH,0) . . 556 ARSENICUM. Arsenic (ASy 03 ) is usually estimated volumetrically (vide p. 489). With certain precautions arsenic um ma}^ also be precipitated and weighed as sulphide (As^Sg). Process . — The pure, white, massive arsenic (about 0.2) is dissolved in a flask in a small quantit}^ of water contain- ing bicarbonate of sodium or potassium, the liquid being heated. A slight excess of h^^drochloric acid is then added, and sulphuretted hydrogen gas passed through the solu- tion so long as a precipitate falls, the mouth of the flask being stopped by a plug of cotton-wool (to prevent undue access of air and consequent decomposition of the gas, resulting in precipitation of sulphur). The mixture is warmed in the flask and carbonic acid gas passed through it until the odor of sulphuretted hydrogen has nearly dis- appeared ; the precipitate collected on a tared filter, washed ANTIMONY — COPPER. 509 as qniekl}^ as possible with hot water containing a little sulphuretted hydrogen, dried in a water-oven and weighed. 198 parts of arsenic should yield 246 of sulphide of arseni- cum. ANTIMONY. The metal is precipitated in the form of sulpliide (Sb^S.J, with the precautions observed in estimating arsenicum — a small quantity of tartaric acid, as well as hj^drochloric, being added, to prevent the precipitation of an oxj^salt. If the sulphuretted hydrogen be passed through a hot so- lution, the particles of precipitate aggregate better, and the latter may be more quickly filtered out and washed. The experiment may be performed on about half a gramme of pure tartar-emetic : the salt should yield nearly half its weight (49.56 per cent.) of sulphide. According to Fre- senius, the sulphide dried at lOO'^ C. still contains 2 per cent, of water, and must be heated, in a current of carbonic acid gas, until it turns from an orange to a black color, before all moisture is expelled. In the British Pharmaco- peeia the purity of tartar-emetic {Antimonium Tartaratum)^ and the strength of solution of chloride of antimony {Li- quor Antimonii Ghloridi)^ are determined by the above process. COPPER. Copper is precipitated from its solutions and weighed either (I) as metal (Ciq), or (2) as oxide (CuO). Process I. — Dissolve about half a gramme of dry crystal- lized sulphate of copper in a small quantity of water, in a tared porcelain crucible or beaker, acidulate with hydro- chloric acid, introduce a fragment or two of pure zinc, cover the vessel with a watch-glass, and set aside till evo- lution of hydrogen has ceased and the still acid liquid is colorless. The copper is then washed with hot water by decantation until no trace of acid remains, the precipitate drained, rinsed with strong spirit of wine, dried in the water-oven, and weighed. Process 2. — About three-fourths of a gramme of sulphate of copper is accurately weighed, dissolved in half a litre of water, the liquid boiled ; dilute solution of potash or soda is then added till no more precipitate falls, ebullition con- tinued for a short time, and the beaker set aside ; the super- natant liquid is decanted, the precipitate boiled with water 43* 510 QUANTITATIVE ANALYSIS. twice or thrice, collected on a filter, washed, dried, trans- ferred to a crucible, the filter incinerated, and its ash moist- ened with a drop of nitric acid ; the whole is finally heated strongly, cooled, and weighed. 249.5 parts of sulphate of copper ^deld ^9.5 of oxide, or 63.5 of metal. BISMUTH. Dissolve 0.3 or 0.4 of pure oxycarbonate of bismuth (26402003,1120) (Bismuthi Garbonas^ B. P.) in a small quantity of h^^drochloric acid, dilute with water slightly acidulated b^^ hydrochloric acid, pass excess of sulphuretted hydrogen through the liquid, collect the precipitate on a tared filter, wash, dry at 100*^ C., and weigh. The sul- phide must not be exposed too long in the water-oven, or it will increase in w^eight owing to absorption of oxygen ; hence it should be tested in the balance every half-hour during desiccation. 5n of oxycarbonate should yield 512 of sulphide (Bi 2 S 3 ). The strength of the official solution of citrate of bismuth and ammonium {Liquor Bismuthi et Ammonise Gitratis^ B. P.) is determined by this process. “Three fluidrachms of the solution, mixed with an ounce of distilled water, and treated with sulphuretted hydrogen in excess, yield a black precipitate, which, collected, washed, and dried, weighs 9.92 grains. One fluidrachm yields three grains of oxide of bismuth.’’ The atomic weight of bismuth is 208. MERCURY. This element may be (1) isolated and estimated in the form of metal, or precipitated and weighed as (2) mercu- rous chloride, or (3) mercuric sulphide. Process 1. — The process by which the metal itself is separated is one of distillation, into a bulb surrounded by water. About half a metre of the difficultly fusible Ger- man glass known as combustion-tubing is sealed at one end after the manner of a test-tube ; a mixture of bicarbonate of sodium and dry chalk is then dropped into the tube to the height of two or three centimetres, and, next, several small fragments of quicklime so as to occupy another centi- metre ; a mixture of about a gramme of pure calomel or corrosive sublimate with enough powdered quicklime to occupy 10 or 12 centimetres of the tube is added, then the lime-rinsings of the mixing-mortar, a la^^er of a few centi- GRAVIMETRIC ESTIMATION OF MERCURY. 511 metres of powdered quicklime, and finally a plug of asbestos (a fibrous mineral unaffected by beat). The whole powder should occupy two-thirds of the length of the tube. The part of the tube just above the asbestos is now softened in the blowpipe-flame and drawn out about a decimetre to the diameter of a narrow quill ; it is again drawn out to the same extent at a point about two or three centimetres nearer the mouth, and any excess of tubing cut off. The bulb thus formed may be enlarged by softening and blow- ing. The tube is next softened at a point close to but an- terior to the asbestos, and bent nearly to a right angle ; the tube is then softened close to the bulb and slightly bent so that the bulb may be parallel with the large tube ; then softened on the other side of the bulb, and the narrow ter- minal tube bent to a right angle, so that, the tube being held in a horizontal position, the bulb may be sunk in water, and the terminal tube point upwards. The long tube is now laid in the gas-furnance found in most laboratories, a basin so placed that the bulb of the apparatus may be cooled by being surrounded by w'ater, the part of the tube occupied by asbestos heated to redness, and the flame slowly length- ened until the whole tube is red-hot. Under these circum- stances the mercurial compound volatilizes, is decomposed by the lime, and its acidulous radical fixed, the mercury carried in vapor to and condensed in the bulb, the carbonic acid gas evolved from the bicarbonate of sodium and chalk washing out the last portions of mercuiy -vapor from the tube. When the distillation is considered to be complete, the dish of water is removed, the bulb dried, and then de- tached by help of a file at a point beyond any sublimate of mercury. The bulb is lastly weighed, the mercury shaken, or dissolved out, and the tube again dried and weighed. Process 2. — The process by which mercury is separated in the form of calomel consists in adding hydrochloric and phosphorous acids {vide p. 312) to an aqueous or even acid solution of a weighed quantity of the mercurial com- pound, setting the mixture aside for twelve hours, collecting the precipitate on a tared filter, washing, drying at 100"^ C., and weighing (Rose). The experiment may be tried on half a gramme to a gramme of corrosive sublimate. Process 3. — Two or three decigrammes of corrosive subli- mate are dissolved in water, the solution acidulated with hydrochloric acid, excess of sulphuretted hydrogen passed, the precipitate collected on a tared filter, washed with cold water, dried at 100^ C., and weighed. 512 QUANTITATIVE ANALYSIS. Proportional weights of equivalent quantities of mercury and its salts. Metal . Hg . . . . 200 Mercurous chloride . HgCl . . . 235.5 Mercuric chloride . . . HgCl . . . 271 Mercuric sulphide . . . HgS . . . . 232 LEAD. Lead is generally estimated either as (1) oxide, (2) sul- phate, or (3) chromate. Process 1. — Weigh out one or two grammes of pure acetate of lead in a covered crucible, previously tared, and heat slowly until no more vapors are evolved. Remove the lid, stir down the carbonaceous mass with a clean iron wire, and keep the crucible in the flame so long as any car- bon remains unconsumed. Introduce some fragments of fused nitrate of ammonium, and again ignite until no metallic lead remains, and all excess of the nitrate has been decomposed. Cool and weigh the resulting oxide (PbO). Process 2. — Dissolve 0.4 or 0.5 of a gramme of acetate of lead in a small quantity of water, drop in diluted sulphuric acid, add to the mixture twice its bulk of methylated spirit of wine, and set aside. Decant the supernatant liquid, col- lect the sulphate on a filter, wash with spirit, dry, transfer to a porcelain crucible, removing as much of the sulphate as possible from the paper, incinerate on the crucible-lid (not in a platinum coil, for the particles of reduced lead would unite with the platinum by fusion), ignite, cool, and weigh. Process 3. — About half a gramme of acetate of lead is dissolved in two or three hundred c. c. of water, acetic acid added, and then solution of red chromate of potassium. Collect the precipitate on a tared filter, wash, dry at 100° C., and weigh. Molecular weights of salts of lead. Metal . . . . Pb 207 Acetate . . . Pb2C,H30,,3H,0 . 379 Oxide . . . PbO . ‘ . 223 Sulphate . , , PbSO, 303 Chromate . , , PbCrO, .... 323.5 CUPEL LATION. 513 SILVER. Compounds of silver which are readily decomposed by heat are estimated in the form of (1) metal, others usually as (2) chloride (AgCl),but sometimes as (3) cyanide (AgNC). Process 1. — Heat about a gramme of oxide of silver (Ag^O) in a tared crucible, cool, and weigh. 232 of oxide yield 216 of metal. “ 29 grains heated to redness yield 27 grains of metallic silver.’^ — Brit. Pharm. Process 2. — Dissolve 0.4 or 0.5 of pure dry crystals of nitrate of silver in water, acidulate with two or three drops of nitric acid, slowly add hydrochloric acid, stirring rap- idly, until no more precipitate falls. Pour off the super- natant liquid through a filter, wash the chloride of silver once or twice with hot water, transfer to the filter, com- plete the washing, and dry. After removing as much as possible of the precipitate from the paper to the crucible, burn the filter, letting its ash fall on the inverted lid of the crucible, moisten with a drop of nitric acid, warm, add a drop of hydrochloric acid, evaporate to dryness, replace the lid on the crucible, ignite the whole, until the edges of the mass of chloride begin to fuse ; cool and weigh. 170 of nitrate yield 143.5 of chloride. According to the British Pharmacopoeia, 10 parts of nitrate should thus yield 8.44 of chloride, and the filtrate from the chloride evaporated to dryness should leave no residue, indicating absence of nitrates of potassium or sodium and other simi- lar adulterants. Pi'ocess 3 Cyanide of silver may be collected on a tared filter and dried at 100° C. 170 of nitrate yield 134 of cyanide. Silver and its salts may be volumetrically estimated by a standard solution of chloride of sodium. Cupellatwn . — The amount of silver in an alloy may be also deter- mined by a dry method. The metal is folded in a piece of thin sheet lead, placed on a cupel (cupella, little cup, made of compressed bone- earth) and heated in a furnace, the cupel being protected from the direct action of flame by a muff-shaped, or, rather, oven-shaped case termed a mufile. The metals melt, the baser become oxidized, the oxide of lead fusing and dissolving the other oxides ; the fluid oxides are absorbed by the porous cupel, a button of pure silver remaining. An alloy suspected to contain 95 per cent, of silver requires about 3 times its weight of lead for successful cupellation ; if 92^ per cent. (English silver coin), between 5 and 6 times as much lead is necessary. 514 QUANTITATIVE ANALYSIS. QUESTIONS AND EXERCISES. 1035. Explain the gravimetric process by which the strength of the oflBcial solutions of ferric chloride, nitrate, and sulphate are de- termined. 1036. Mention the various amounts of ferrous and ferric salts equivalent to 100 parts of metal. 1037. State the precautions necessary to be observed in estimating arsenicum or antimony in the form of sulphide. 1038. In what form are the official compounds of bismuth weighed for quantitative purposes ? 1039. Give an outline of the process by which mercury may be isolated from its official preparations and weighed in the metallic condition. 1040. Describe three methods for the quantitative analysis of salts of lead ; and the weights of the respective precipitates, supposing 0.56 of crystallized acetate to have been operated on in each case. 1041. Describe the process by which silver is estimated in the forms of metal, chloride, and cyanide. 1042. What proportions of nitrate of silver are indicated, respec- tively, by 15 of metal, 9.8 of chloride, and 8.1 of cyanide ? 1043. Define cupellation. ESTIMATION OF THE ACIDULOUS EADICALS OF SALTS. CHLORIDES. Free chlorine (chlorine-water) and compounds which by action of acids 3 deld free chlorine (Chlorinated Lime, Chlo- rinated Soda, and their official Solutions) are estimated volumetrically hy a standard solution of hyposulphite of sodium ( vide p. 493). The amount of combined chlorine in pure chlorides (HCl,NaCl) ma}^ also be determined b}^ A'Olumetric analy^sis with a standard solution of nitrate of silver (p. 486). Combined chlorine is gravimetrically estimated in the form of chloride of silver, the operations being identical with that just described for silver salts ; 58.5 parts of pure, !. colorless, crystallized chloride of sodium (rock-salt) ^deld ! 143.5 of chloride of silver. j I IODIDES. 1 Free iodine is estimated volumetrically by solution of j hyposulphite of sodium {vide p. 493).. ' Combined iodine is determined gravimetrically in the j form of iodide of silver, the operations being conducted as j' BROMIDES — CYANIDES — NITRATES. 515 with chloride of silver. Iodide of potassium may be used for an experimental determination : KI = 166 should ^deld Agl = 235. Of the official iodide of cadmium (Gadmii lodidiim^ B. P.) it is stated that “ ten grains dissolved in water, and nitrate of silver added in excess, give a pre- cipitate which, when washed wdth water and afterwards with half an ounce of solution of ammonia, and dried, weighs 12.5 grains.’’ In presence of chlorides and bromides the iodine in iodides may be precipitated and weighed as iodide of palladium. BROMIDES. Free bromine may be estimated by shaking with excess of solution of iodide of potassium, and then determining the equivalent quantity of liberated iodine by a standard solution of hyposulphite of sodium (p. 493). The bromine inbromides maybe precipitated and weighed as bromide of silver, the manipulations being the same as those for chloride of silver : 0.2 to 0.3 of pure bromide of potassium may be used for an experimental analysis. CYANIDES. The hydrogen cyanide (h 3 'drocyanic acid) is usually estimated volumetrically {ride p. 48T). From all soluble cyanides, cyanogen may be precipitated by nitrate of silver, after acidulating with nitric acid, the cyanide of silver collected on a tared filter, dried at 100° C., and weighed. Of the official Diluted Hydrocyanic Acid, it is stated that one hundred grains (or 110 minims) precipitated by solution of nitrate of silver yield ten grains of dry cyanide of silver. Cyanide of Silver. Silver ■ Ag . In 1 molecule. . 107.93 . In ICO parts. . 80.59 Cj^anogen . ON . . 26.00 . . 19.41 133.93 100.00 NITRATES. Nitrates cannot be estimated by direct gravimetric ana- Ij^sis, none of the baysylous radicals yielding a definite nitrate insoluble in water. With some difficulty they may be determined by indirect volumetric methods. 516 QUANTITATIVE ANALYSIS. Process . — The best method is that by Crum, as modified by Frankland and Armstrong. It consists in agitating with mercury a concentrated solution of the nitrate with a large excess of concentrated sulphuric acid — the whole of the nitrogen being then involved as nitric oxide. From the volume of the latter the weight of nitrate wdience obtained is easily calculated. No chlorides must be present. For educational purposes the experiment may be conducted on 3 or 4 c. c. of a solution of one gramme of pure nitrate of potassium in 100 c. c. of distilled water. From 1 to 10 c. c. of such a solution will very well represent the nitrates in half a litre of well-water. The following is the mode in which this process is ap- plied to the estimation of nitrogen existing as nitrates and nitrites in potable waters. The solid residue from half a litre of water used for determination of total solid constituents* is treated with a small quantity of distilled water, a very slight excess of sulphate of silver is added to convert the chlorides present into sulphates, and the filtered liquid is then con- centrated by evaporation in a small beaker until it is reduced in bulk to two or three cubic centime- tres. The liquid must now be transferred to a glass tube (about as long as the hand) (see fig.) pre- viously filled with mercury at the mercurial trough, and furnished at its upper extremity with a cup and stopcock, the beaker being rinsed out once or twice with a very small volume of recently boiled distilled water, and finally with pure and concen- trated sulphuric acid in somewhat greater volume than that of the concentrated solution and rinsings. (For a method of purifying the acid vide p. 276.) By a little dexterity it is easy to introduce suc- cessively the concentrated liquid, rinsings, and sulphuric acid by means of the cup and stopcock, without the admission of any trace of air. Should, however, air inadvertently gain admittance, it is * If the water contains nitrites, a separate half litre should be taken for this determination, otherwise there is a risk of loss of nitro- gen during evaporation. The nitrites in this half litre of water must be transformed into nitrates by the cautious addition of potassic permanganate to the slightly acidified water before the evaporation is commenced. Immediately after the action of the permanganate the water must be again rendered slightly alkaline. SULPHIDES. 517 readily removed by depressing the tube in the mercury trough, and then momentarily opening the stopcock. If this be done within a minute or two after the introduction of the sulphuric acid, no fear need be entertained of the loss of nitric oxide, as the evolution of this gas does not begin until a minute or so after the violent agitation of the contents of the tube. The acid mixture being thus introduced, the lower ex- tremity of the tube is to be firml 3 ^ closed by the thumb, and the contents violently agitated b}^ a simultaneous vertical and lateral movement, in such a manner that there is always an unbroken column of mercuiy, at least an inch long, at the bottom part of the glass tube. From the description, this manipulation ma}^ appear difficult ; but in practice it is extremely" simple, the acid liquid never coming in contact with the flesh. In about a minute from the commencement of the agitation a strong pressure begins to be felt against the thumb of the operator, and mereuiy spurts out in mi- nute streams, as nitric oxide gas is evolved. The escape of the metal should be gently" resisted, so as to maintain a considerable excess of pressure inside the tube, and thus prevent the possibility of air gaining access to the interior during the shaking. In from three to five minutes the reaction is completed, and the nitric oxide ma^" then be transferred to a suitable measuring-apparatus, where its volume is to be determined over mercury. As half a litre of water is used for the determination, and as nitric oxide occupies exactlj" double the volume of the nitrogen which it contains^ the volume of nitric oxide read off expresses the volume of .nitrogen existing as nitrates and nitrites in one litre of the water. From the number so obtained, the weight of nitrogen in these forms in 100,000 parts of water is easil}^ calculated. (1 litre of H weighs .0896, and N. is 14 times as heaAy as H : 101 of KNO 3 contains 14 of N.) SULPHIDES. Process 1 . — Soluble sulphides (H.,S, NaHS, e.g,) ma}^ be determined volumetrically by adding to the aqueous liquid a measured excess of an alkaline solution of arsenic of known strength, neutralizing by hydrochloric acid, diluting to an\" given volume, filtering off the sulphide of arsenicum precipitated, taking a portion of the filtrate equal to half or a third of the original volume, and, after neutralizing by acid carbonate of sodium, estimating the residual arse- 44 518 QUANTITATIVE ANALYSIS. iiic by the standard iodine solution {vide p. 488). The process may be tried on a measured volume of sulphuretted hydrogen (the weight of which is easily calculated ; 1 litre ' of hydrogen = 0.0896 gramme) absorbed by a strong solu- tion of soda or potash. Process 2. — Sulphur and sulphides may also be quanti- tativel}^ analyzed by oxidizing to sulphuric acid and pre- cipitating in the form of sulphate of barium. A couple of decigrammes of a pure metallic sulphide may be decom- posed by careful deflagration with a mixture of chlorate i of potassium and carbonate of sodium, the product dis- i solved in water, acidulated with hydrochloric acid, solution of chloride of barium added, and the precipitated sulphate of barium purified and collected as described in connection wdth the estimation of barium (p. 502). Many sulphides may be oxidized in a flask by chlorate of potassium and hj^drochloric acid, and then precipitated by chloride of barium. Experimental determinations may also be made on a weighed fragment of sulphur, about 0.1, cautiously fused with a solid caustic alkali, and the product oxidized while hot by the slow addition of powdered nitrate or chlorate of ])otassium, or, when cold, b}" treatment with chlorate of potassium and hydrochloric acid, and subse- quent precipitation by chloride of barium. Note . — Fusions performed by help of a gas-lamp must be care- fully conducted; for any alkali that may creep over the side of a crucible will certainly absorb sulphurous acid from the products of combustion of the gas, and error result. Process 3. — Soluble sulphides may" also be treated with excess of an alkaline arseniate, arsenious sulphide be then precipitated by the addition of hy^drochloric acid, and the precipitate collected and weighed with the usual precau- tions {cide p, 508). Weights of equivalent quantities of sulphur and its compounds. Sulphur . s . 32 Sulphuretted hydrogen . . II, s .... . 34 Sulphate of barium . . . . BaSO, . . . . 233 Arsenious sulphide . . . . (As,S3)-^3 . . . 82 Ilisulphide of iron . . . (FeS,)-r-2 . . . GO Sulphide of lead . . . . PbS .... . 239 SULPHITES — SULPHATES — CARBONATES. 519 SULPHITES. Sulphites are usually estimated volumetrically by a standard solution of iodine {mde p. 488). Sulphites insolu- ble in water are diffused in that menstruum, hydrochloric acid added, and the iodine solution then dropped in. If necessary, sulphites may be estimated gravimetri- eally by oxidation and precipitation in the form of sulphate of barium. SULPHATES. These salts are always precipitated and weighed as sul- phate of barium, the manipulations being identical with those performed in the determination of barium by means of sulphates {mde p. 502). The purity of Sulphate of Sodium (Sodae Sulphas^ B. P.), and the presence of not more than a given amount of sulphuric acid in Vinegar {Acetum^ B. P.), are directed, in the British Pharmacopoeia, to be ascertained by this process. Ten grains of sulphate of sodium yield 7.236 of sulphate of barium. Five ounces of vinegar should yield not more than about one-third of a gramme of sulphate of barium. Proportional weights of equivalent quantities of sulphates. The sulphuric radical . . . SO^ 96 Sulphuric acid H^SO^ .... 98 Sulphate of barium .... BaSO^ .... 233 CAHBONATES. Carbonates are usually estimated by the loss in weight they undergo on the addition of a strong acid. Process 1. — A small light flask is selected — of such a size that it can be conveniently weighed in a delicate balance. Two narrow glass tubes are fitted to the flask by a cork ; the one straight, extending from about two or three centimetres above the cork to the bottom of the flask ; the other cut off close to the cork on the inside and curved outwards so as to carry a thin drying-tube horizontally above the flask. The diying-tube may be a short narrow test-tube, the bottom of which is constricted so as to form a narrow tube open at the end ; it is nearly filled with small pieces of chloride of calcium, a plug of cotton-wool preventing escape of any fragments at either end, and is attached by a pierced cork to the free extremity of the curved tube of the flask. A weighed quantity of an 3 ^ pure 520 QUANTITATIVE ANALYSIS. soluble carbonate is placed in the flask, a little water added, a miniature test-tube containing sulphuric acid lowered into the flask by a thread and supported so that the acid may not flow out^ the cork inserted, the outer end of the piece of the straight glass tubing closed by a frag- ment of cork or wax, and the whole weighed. The appa- ratus is then inclined so that the oil of vitriol and carbon- ate may slowly react ; carbonic acid gas is evolved and escapes through the horizontal tube, any moisture being retained by the chloride of calcium. When effervescence has ceased, the gas still remaining in the vessel is sucked out; this is accomplished by adapting a piece of India- rubber tubing to the end of the drying-tube, removing the small plug from the straight tube, and aspirating slowly with the mouth for a few minutes. If the heat pro- duced by the action of the oil of vitriol and solution is considered insufficient to expel all the carbonic acid from the liquid, the plug is again inserted in the tube and the con- tents of the flask gently boiled for some seconds. When the apparatus is cold, more air is again drawn through it, and the whole finally weighed. The loss is due to carbonic acid gas (CO 2 ), from the weight of which that of any car- bonate is ascertained by calculation. Carbonates insoluble in water may be attacked by hj^drochloric instead of sul- phuric acid; granulated mixtures of carbonates and pow- dered tartaric or citric acids by inclosing the preparation in the inner tube and placing water in the flask, or vice versa. The apparatus also may be modified in many ways to suit the requirements, convenience, or taste of the ope- rator. \ Process 2. — Carbonates from which carbonic acid gas is evolved by heat may be estimated by the loss they expe- rience on ignition. Process 3. — Free carbonic acid gas may be absorbed by a solid stick of potash or a strong alkaline solution, the loss in volume of the gas or mixture of gases indicating the amount originally present. ; Weights of eguivalent quantities of carhonic acid gas and } certain carbonates. j Carbonic acid gas CO.^ . . . 44 | Carbonic acid H^CO, . . 62 ji Anh^ulrous carbonate of sodium . . Na^COy . . 106 fi Anhydrous carbonate of potassium . . . 138 Carbonate of calcium CaCOa . . 100 ji OXALATES PHOSPHATES. 521 OXALATES. Process 1. — The oxalic radical is usually precipitated in the form of oxalate of calcium, and weighed as carbonate, the manipulations being identical with those observed in the estimation of calcium {vide p. 504). The experiment may be performed on 0.3 or 0.4 of pure crystallized oxalic acid, 126 parts of which should yield 100 of carbonate of calcium. Process 2. — Oxalates may also be determined byconver- sion of their acidulous radical into carbonic acid gas, and observation of the weight of the latter. The oxalate, water, and excess of black oxide of manganese are placed in the carbonic acid apparatus, a tube full of oil of vitriol lowered into the flask, the whole weighed, and the opera- tion completed as for carbonates. From the following equation it will be seen that every 88 parts of carbonic acid gas evolved indicate the presence of 126 parts of crystallized oxalic acid or an equivalent quantity of other oxalate : — + MnO., + 2H,SO, = MnSO, + JSFa.SO, -f 2H,0 + 2CO^. The black oxide of manganese used in this experiment must be free from carbonates. The amount of materials employed is regulated by the size of the vessels. PHOSPHATES. Process 1. — From phosphates dissolved in water ^ the phosphoric radical may be precipitated and weighed in the form of pyrophosphate of magnesium, the details of ma- nipulation being similar to those observed in estimating magnesium {vide p. 505). Half a gramme or rather more of pure dry crystallized phosphate of sodium may be emplo^'ed in experimental determinations. The official phosphate of ammonium {Ammonise Phosphas^ B. P.) is quantitatively analyzed by this method. If twenty grains of this salt be dissolved in water, and solution of ammonio-sulphate of magnesia added, a crystalline pre- cipitate falls, which, when well washed upon a filter with solution of ammonia diluted with an equal volume of water, dried, and heated to redness, leaves 16.8 grains.’’ Half a gramme or less is a more convenient quantity, if the operations be conducted with care. Solution of am- 44* 522 QUANTITATIVE ANALYSIS. monio-sulpliate of magnesium (B. P.) is prepared by dis- solving 2 parts of sulphate of magnesium, 1 of chloride of ammonium, and 1 of solution of ammonia ( 20.6 per cent. KH^HO) in 18 or 20 of distilled water ; such a solution is of considerable use if several phosphoric determinations are about to be made. Process 2. — Free phosphoric acid is most readily deter- mined as phosphate of lead (Pb 32 POJ. Of the official solution of phosphoric acid it is stated that 355 grains by weight poured upon 180 grains of oxide of lead in fine powder leave, by evaporation, a residue (principally phos- phate of lead) which, after it has been heated to dull red- ness, weighs 215.5 grains.” One-tenth of these quantities may be used for experimental purposes; one to two grammes will give good results. The oxide of lead must be quite pure ; it should be prepared by digesting red lead in warm dilute nitric acid, washing, drying, and heating the result- ing puce-colored plumbic oxide in a covered porcelain crucible. The increase in weight obtained on evaporating a given amount of solution of phosphoric acid with a known weight of perfectly pure oxide of lead (PbO) may be regarded as entirely due to phosphoric anh^^dride (PA), 3PbO + P,0, = Pb,2PO„ the actual reaction being. 3PbO + 2 H 3 PO, = Pb 32 PO, -f 3H,0. From these equations, and the table of atomic weights {vide Appendix), the percentage of phosphoric acid (H 3 PO 4 ) in any specimen of its solution may be easily calculated. Process 3. — The strength of pure solution of phosphor'ic acid may be ascertained by specific gravity and reference to Tables. Process 4. — Bone-earth, “ superphospate,” the Calcis Phosphas of pharmacy, and other forms of phosphate of calcium known to be tolerably free from iron or alumi- nium, may be estimated by treating about half a gramme with hydrochloric acid somewhat diluted, filtering if necessary, warming, precipitating with excess of ammonia, collecting the precipitate (Ca.j 2 POJ washing, drying, igni-* ting, and weighing. ‘‘ Calcis phosphas f if pure, wdll, in this process, lose no weight. Process 5. — Insoluble phosphates in ashes, manures, etc.. i QUESTIONS AND EXERCISES, 523 are treated as follows : a weighed quantity of the material (1.0 to 10.0) is digested in hydrochloric acid diluted with three or four times its bulk of water ; filtered (insoluble matter and filter being thoroughly exhausted by water) ; ammonia added to the filtrate and washings until, after stirring, a faint cloudy precipitate is perceptible ; solution of oxalic acid dropped in until, after agitation for a few minutes, the opalescence is removed ; oxalate of ammonium next added, the whole warmed, oxalate of calcium removed by filtration, and the filtrate concentrated if very dilute ; the liquid treated with citric acid in such quantity that ammonia when added in excess gives a clear lemon-yellow solution (Warington), magnesian mixture poured in (as in Process 1), and the precipitate of ammonio-magnesian phosphate collected, washed, dried, and weighed as already described in connection with the estimation of magnesium. Relative weights of equivalent quantities of phosphoiHc compounds. Phosphoric acid H 3 PO^ 98 Pyrophosphate of magnesium (Mg 3 P.^O^ = 222)-i-2= 111 Phosphate of lead .... (Pb 32 PO^ = 811) -^2= 405.5 Phosphoric anhydride . . . (P205=142) —2= H Phosphate of calcium . . . (Caj2PO^=310) ~ 2= 155 Superphosphate of calcium (CaH^2PO^=234) -r- 2= lit QUESTIONS AND EXERCISES. 1044. What quantity of pure rock-salt is equivalent to 4.2 parts of chloride of silver? — Ans. 1.712. 1045. State the percentage of real iodide of potassium contained in a sample of which 8 parts yield 10.9 of iodide of silver. — Ayis. 96.25. 1046. What is the strength of a solution of hydrocyanic acid 10 parts of which, by weight, yield .9 of cyanide of silver ? — Ans. 1.81 per cent. 1047. How are nitrates quantitatively estimated ? 1048. By what processes may the strength of sulphides be deter- mined ? . 1049. How much real sulphate of sodium is contained in a speci- men 10 parts of which yield 14.2 of sulphate of barium ? — Ans. 86.34 per cent. 1050. Give details of the operations performed in the quantitative analysis of carbonates. 524 QUANTITATIVE ANALYSIS. 1051. What amount of carbonic acid gas should be obtained from 10 parts of acid carbonate (or bicarbonate) of potassium ? — Ans. 4.4 parts. 1052. To what operation and what quantities of materials does the following equation refer ? Na,OA + MnO,+ 2H,SO,= MnSO,+ Na^SO, + 2H,0 + 2CO,. 1053. Explain the lead process for the estimation of phosphoric acid in the official solution. 1054. State the amount of superphosphate of calcium equivalent to 7.6 parts of pyrophosphate of magnesium. — Ans. 8.01 parts. SILICATES. j Silica (SiOg) may be separated from alkaline silicates, or j from silicates decomposable by hydrochloric acid, by digest- i ing the substance in hydrochloric acid at a temperature of | 70^ or 80° C., until completely disintegrated, evaporating to dryness, heating in an air-bath, again moistening with acid, diluting with hot water, filtering, washing, drying, igniting, and weighing. ESTIMATION OF WATER. W^ater, being readily volatilized, is most usually estimated by the loss in w^eight which a substance undergoes on being heated to a proper temperature. Thus, in the British Pharmacopoeia, crystalline gallic acid (HgC^HgO., H^O) is stated to lose 9.5 per cent, of its weight at a temperature of 100° C., oxalate of cerium (CeC.^O^, BH^O) 52 per cent, on incineration, carbonate of potassium about 16 per cent, on exposure to a red heat, sulphate of quinine ( 2 C 2 oH,,_jN,, 02 , IT^SO^, 7H.^O) 14.4 per cent, at 100° C., arseniate of sodium (Na.^HAsO^, iH20) 40.38 per cent, at 149° C., carbonate of sodium (Na^COg, lOH^O) 63 per cent., phosphate of sodium (Na 2 HPO^, I 2 H 2 O) 63 per cent., and sulphate of sodium (Na.^SO^, IOH 2 O) 55.9 per cent, at a low red heat. Process . — One or two grammes of substance is sufficient in experiments on desiccation, the material being placed in a watch-glass, covered or uncovered porcelain crucible, or other vessel, according to the temperature to which it is to be exposed. Rapid desiccation at an exact temperature may be effected by introducing the substance into a tube’ liaving somewhat the shape of the letter U, sinking the lower part of the tube into a liquid kept at a definite tem- perature by aid of a tliermoineter, and drawing or forcing CARBON, HYDROGEN, OXYGEN, NITROGEN. 525 a current of dry air slowly through the apparatus. Sub- stances liable to oxidation may be desiccated in a current of dried carbonic acid gas. The weights of the U-tube before and after the introduction of the salt, and after desiccation, give the amount of water souglit. In all cases the material must be heated until it ceases to lose weight. Occasionally it is desirable to estimate water directly by conveying its vapor in a current of air through a weighed tube containing chloride of calcium and re-weighing the tube at the close of the operation ; the increase shows the amount of water. Note. — Highly dried substances rapidly absorb moisture from the air ; they must therefore be weighed quickly, inclosed, if possible, in tubes (p. 498), a pair of clamped watch-glasses, or a crucible having a tightly fitting lid. CARBON. HYDROGEN, OXYGEN, NITROGEN. The quantitative analysis of animal and vegetable substances is either pi'oximate or ultimate. Proximate analysis includes the estimation of water, oil, albumen, starch, cellulose, gum, resin, alka- loids, acids, glucosides, ash. It requires the application of much theoretical knowledge and manipulative skill, and cannot well be studied except under the guidance of a tutor. The best published work on the subject is by Rochleder, a translation of whose mono- graph will be found in the Pharmaceutical Journab vol. i. 2d ser. pp. 562, 610 ; vol. ii. 2d ser. pp. 24, 129, 160, 215, 274, 420, 478. Ultimate orga^iic analysis can only be successfully accomplished with the appliances of a well-appointed laboratory — a good balance, a gas-furnace giving a smokeless flame (7 or 8 centimetres wide and 70 or 80 centimetres long), special forms of glass apparatus, etc. The theory of the operation is simple : a weighed quantity of a sub- stance is burnt to carbonic acid gas (002 = 44) and water (H20=18), and these products collected and weighed ; 12 parts in every 44 of carbonic acid gas (=/y) are carbon, 2 in every 18 of water (=^) are hydrogen ; nitrogen if present escapes as gas. If nitrogen be a constituent, more of the substance is strongly heated with a mixture of the hydrates of sodium and calcium ; these bodies then split up into oxides, oxygen, and hydrogen ; the oxygen burns the carbon of the substance to carbonic acid gas, its hydrogen and nitrogen appearing as water and ammonia respectively ; the carbonic acid and water are disregarded, the ammonia collected and weighed in the form of a double chloride of platinum and ammonium (PtCb2NH^Cl =447), of which 28 parts in every 447 are nitrogen. The ‘difference between the sum of the weights of hydrogen and carbon, and the weight of substance taken, is the proportion of oxygen in the body, supposing nitrogen to be absent. If nitrogen is present, the difference between the sum of the percentages of carbon, hydrogen, and nitrogen, and 100, is the percentage of oxygen. Shortly, carbon 526 QUANTITATIVE ANALYSIS. is estimated in the form of carbonic acid gas, hydrogen as water, nitrogen as ammonia, and oxygen by loss. The folloiDingis the outline of the necessary manipulations. The source of the oxygen for the combustion of carbon and hydrogen is black oxide of copper in coarse powder. 200 or 300 grammes of this material are heated in a crucible to low redness for a short time to expel every trace of mois- ture ; then transferred to tubes (store-tubes) resembling test-tubes, half a metre long, and having a slightly narrowed mouth, the tube being held in a cloth to protect the hand while the hot oxide is being directly introduced into the mouth of the tube by a scooping motion. As soon as the well-corked tube is cool, the oxide is poured, portion by portion, into a similar tube (the combustion tube), some- what longer, drawn out to a quill (bent upwards nearly to a right-angle) at one end, not constricted at the mouth, and containing a few decigrammes of fused chlorate of potas- sium. After ten or fifteen centimetres of oxide have been l)Oured in, about a decigramme of the substance to be analyzed is dropped down the tube, then a few grammes of oxide, then another decigramme of substance, then more oxide, until three or four decigrammes of the body under examination have been added. The fifteen or twenty centimetres of alternate layers are next thoroughly mixed by a long copper wire having a short helix, more oxide is introduced, the wire cleansed by twisting the helix about in the pure oxide, and a plug of asbestos finally placed on the top of the oxide at about five centimetres from the mouth of the tube; the tube is then securely corked and set aside. The substance operated on may be pure white sugar, powdered and dried ; the tube in which it is contained is weighed before and after the removal of a portion for combustion, the loss is the quantity employed in the experi- ment. If the combustion-furnace is powerful, or the com- bustion-tube not of the hardest glass, the tube should be inclosed in wire gauze the elasticity of which has been destroyed by heating to redness. In the combustion of substances containing nitrogen, the plug of asbestos must be displaced by one of copper turnings, which serve to reduce any oxides of nitrogen, and thus insure the escape of nitrogen itself. The water produced when the prepared tube is heated, is collected in a small U-tube containing pieces of chloride of calcium, or pumice-stone moistened with sulphuric acid ; the carbonic acid gas in a series of CARBON, HYDROGEN, OXYGEN, NITROGEN. 521 bulbs containing solution of potash (sp. gr. about 1.2T). These bulbs may be purchased at any apparatus-shop. The chloricle-of-calcium tube is fitted by a good cork to the combustion-tube, the potash-bulbs by a short piece of India- rubber tubing to the chloride-of-calcium tube. The potash- bulbs may carry a short light tube containing a rod of caustic potash three or four centimetres long; this serves to arrest any moisture that might be carried away from the solution of potash by the dried expanded air which escapes during the operation. The combustion-tube having been placed in the furnace, and the drying-tube and potash- bulbs weighed and attached, the gas is lit under the asbes- tos, and, when the tube is red-hot, the flame slowly extended until nearly the whole tube is at the same temperature, the operation being conducted at such a rate that bubbles of gas escape through the bulbs at about the rate of one per second. When no more gas passes, the extremity of the tube containing the chlorate of potassium is gently heated until ox 3 ^gen ceases to be evolved; the quilled extremity of the combustion-tube is then broken, and air drawn slowly through the apparatus by suction through an India-rubber tube fixed on the free end of the potash- bulbs, perfect combustion of carbon and removal of all carbonic acid gas is thus insured. The drying-tube and bulbs are disconnected and weighed ; the increase in weight due to carbonic acid gas and water respectively noted, and the percentages of carbon, h^^drogen, and (by loss) oxygen calculated. This method is that of Liebig, with modifica- tions by Bunsen ; good combustion-furnaces are those known as Hofmann’s and Griffin’s. The general mojiipulations for substances containing nitrogen resemble the foregoing so far as the use of a com- bustion-tube and furnace and collection of the ammoniacal gas are concerned. The combustion-tube must be quilled at one end, and about a third of a metre long. The soda- lime is made by slaking quicklime with a solution of soda, of such a strength that about two parts of quicklime shall be mixed with one of hydrate of sodium, drying the pro- duct, heating to bright redness, and finely powdering ; it should be preserved in a well-closed bottle. Some of the soda-lime is introduced into the tube, then layers of sub- stance and soda-lime, mixture effected by a wire, more soda- lime added, and lastly a plug of abestos. Bulbs, known as those of Will and Yarrentrapp (the originators of the method), containing hydrochloric acid of about 25 per cent.. 528 QUANTITATIVE ANALYSIS. are then fitted by a cork, and the tube Ideated in the fur- nace. When gas ceases to pass, the quill is broken, and aspiration continued slowly until ammoniacal gas may be considered to have been all removed. The bulbs are dis- connected, their contents and rinsings poured into a small dish, solution of perchloride of platinum added, and the operation completed as in the estimation of ammonium and potassium salts {vide pages 502 and 499). Liquids are analyzed by a similar method to that adopted for solids, volatile liquids being inclosed in small bulbs having a long quill. These are weighed previously to and after the introduction of the liquid; just before being dropped into the combustion tube the quill is broken. Formulse, — From the percentage composition of an or- ganic substance an empirical formula may be deduced by dividing the weight of each constituent by its atomic weight, j and converting the product into the simplest whole num- bers ; a rational formula by ascertaining the proportion in which the substance unites with a radical or body having a knoTvn combining proportion, etc. { vide p. 873). Chlorine^ bromine^ or iodine contained in an organic substance is usually estimated by heating to redness a given weight of the material with ten times as much pure lime in a combustion-tube. Chloride, bromide, or iodide of calcium is thus produced. While still hot the tube is plunged into water, the mixture of broken glass and pow- der treated with pure diluted nitric acid in slight excess; the filtered liquid precipitated by nitrate of sil- ver, and the chloride, bromide, or iodide of silver collected, washed, dried, and weighed. Sulphur^ phosphorus^ and arsenicum in organic salts may be estimated by gradually heating in a combustion- tube 1 part of the substance with a mixture of 10 parts nitre, 2 dried carbonate of sodium, and 30 chloride of sodium (in order to moderate deflagration). The product is dissolved in water acidulated by nitric acid, the sulphu- ric radical precipitated and estimated as sulphate of barium, the phosphoric and arsenic radicals as ammonio-magnesiaii phosphate or arseniate. QUINIA OR QUININE. A quantitative determination of the purity of commer- cial sulphate of quinia may be made b}’ De Try’s process. 2 grammes of the salt are dissolved in 12 c. c. of distilled QUINIA OR QUININE. 529 water and 1.6 c. c. of diluted sulphuric acid (B. P.). 8 c. c. of solution of hydrate of sodium (1 to 12) and 30 c. c. of pure dry ether are added, the whole well shaken and laid aside for twelve hours. The ethereal solution decanted and evaporated gives the quinia. The aqueous solution, carefully neutralized by acetic acid and strong solution of iodide of potassium (1 in 4) added, gives a white precipi- tate of hydriodate of quinidia,the mother-liquor containing any cinchonia and cinchonidia that may be present. The precipitate is collected on a tared filter, washed, dried^ and weighed ; it contains T1.68 per cent, of pure qiiinidia. The filtrate and washings are rendered alkaline by solution of soda; cinchonia and cinchonidia are precipitated, and ma}" be collected, washed, dried, and weighed. Note, — If the quinia in drying assumes a resinoid cha- racter it should be redissolved in ether, and the solution, when concentrated, allowed to evaporate very slowly or spontaneously. Be Vri/^s method for the separation and quantitative de- termination of all the different cinchona alkaloids. This is based upon the following facts (nomenclature after De Vry) 1. The great solubility of quinine and amorphous alka- loid in ether, and the relative insolubility of qiiinidine, cin- chonidine, and cinchonine in this liquid. 2. The great solubility of the iodo-sulphate of the amor- phous alkaloid in alcohol, and the very small solubility of the iodo-sulphate of quinine (herapathite) in this liquid. 3. The great difference in solubility between the tartrate of cinchonidine and the tartrates of cinchonine and quini- dine — the first being soluble in 1265 parts of water at 10^ C., the second in 35.6 parts of water at 16^ C., and the third in 38.8 parts of water at 15^ C. 4. The great difference in solubility between the hydrio- date of quinidine and the hydriodates of cinchonidine and cinchonine in water and alcohol. 1 part of hydriodate of quinidine requires 1250 parts of water at 15^ C., or 110 parts of alcohol. 1 part of hj'driodate of cinchonidine requires 110 parts of water, or 3 parts of alcohol. 1 part of hydriodate of cinchonine requires 128 parts of water, or 3 parts of alcohol. These facts are applied to the separation and determina- tion of the different cinchona alkaloids in the following manner : — 45 530 QUANTITATIVE ANALYSIS. Five to ten grammes of the pulverized mixed alkaloids are mixed with 50 grammes of ether, and the mixture, after well shaking, left at rest till the next day. By this opera- tion the alkaloids are separated into two parts, viz., one (A) soluble in ether, and another (B) insoluble in that liquid. The part soluble in ether contains the quinine and the amorphous alkaloid, together with traces of quinidine or cinchonidine, whilst the insoluble part contains the cin- chonidine, cinchonine, and quinidine. These two parts are separated by a filter, the insoluble part washed with some ether, and the ethereal solution either evaporated or dis- tilled. A. Part soluble in Ether . — The residue left by the evapo- ration of the ether is dissolved in 10 parts of proof spirit acidulated by one-twentieth of sulphuric acid. To this solu- tion is carefully added an alcoholic solution of iodine till a precipitate is no longer formed. This part of the process is the most difficult, and requires some experience. If the mixed alkaloids contain a large amount of quinine, there appears immediatel}^ a black precipitate of quinine-herapa- thite, wdiereby the addition of the solution of iodine is regu- lated ; but if the amount of quinine is only very small, it may happen that the precipitate of herapathite does not ap- pear immediately. In such a case onl}" a small quantity of iodine must be added, and the liquid, after having been stirred b}^ a glass rod, left till the next day. If quinine is really present, it will then be precipitated in the form of herapathite. The chief desideratum of tliis part of the pro- cess is to add enough and not too much iodine. The hera- pathite is collected upon a filter, washed with strong alcohol, dried upon blotting-paper, and heated in a water-bath. One part of the herapathite, thus dried, represents 0.565 part of pure quinine. The liquid separated from the herapathite is mixed with an alcoholic solution of sulphurous acid, whereby the iodo- sulphate of amorphous alkaloid is converted into hydrio- date, and the red-brown color disappears. The solution is then carefully neutralized by caustic soda, and heated on a water-bath to expel the alcohol, after which it is precipi- | tated by a slight excess of soda. The precipitate consists | of the amorphous alkaloid, containing traces of quinidine | or cinchonidine, if these alkaloids were contained in the ( mixed alkaloids. B. Part Insoluble in Ether . — This part is mixed with 40 parts of hot water, and converted into neutral sulphate by QUINTA OR QUININE. 531 careful addition of diluted sulphuric acid, so that a solution is obtained having a slight alkaline reaction upon red litmus paper. To this solution a solution of tartrate of potash and soda is added in sufficient quantity to convert the sul- phates into tartrates, and, after stirring with a glass rod, it is left till the next day. If cinchonidine be present in ap- preciable quantity, its tartrate will be found separated in crystalline form, whilst the other tartrates remain dissolved ; if only traces of cinchonidine be present striae will be ob- served on every spot of the glass which has been rubbed by the glass rod. The tartrate of cinchonidine is collected upon a filter, washed with a little water, and dried on a water-])atli. One part of this tartrate represents 0.804 part of cinchonidine. The liquor separated from this tartrate is mixed witli a solution of iodide of potassium, and well stirred by a glass rod. If quinidine is present in appreciable quantity, a sandy crystalline powder of hydriodate of quinidine will be precipitated, which is collected upon a filter, washed with a little water, and dried on a water-bath. One part of this hydriodate represents 0.718 part of anhydrous quinidine. If only a trace of quinidine be present, no precipitate will appear, but only strim on every spot of the glass which has been rubbed by the glass rod. The liquor separated from the hydriodate of quinidine is precipitated by caustic soda, whereby the cinchonine is obtained. It is collected upon a filter, washed with water, and dried on a water-bath. Dr. de Try states that he is aware that this process is far from perfect. For instance, the tartrate of cinchonidine and the hydriodate of quinidine, although difficultly soluble in cold water, are not insoluble ; and therefore the quanti- ties of the alkaloids determined by this process are too small, whilst, consequently, that of the cinchonine found is too large. The best part of the process is the accurate determination of the real quinine contained in a bark, and the impossibility of overlooking one of the mentioned five alkaloids which may be contained in a bark. Carles^s Proces^i for the Valuation of Cinch on a-harks . — An average sample of the bark is reduced to fine powder and passed through a sieve without residue. Twenty grammes are then taken and intimately mixed in a mortar with 8 grammes of slaked lime previously mixed with 35 grammes of water. This mixture, spread on a plate, is dried in the air in summer, or on a water-bath at other times. 532 QUANTITATIVE ANALYSIS. When all the moisture has evaporated, the lumps are broken up, and the powder packed in a percolator with a piece of lint at the bottom. Chloroform is then passed tli rough in ' successive portions till thp mass is exhausted. This is ascertained by receiving the last drops in a watch-glass, evaporating to dryness, and pouring on the residue water acidulated with sulphuric acid, then solution of chlorine, and lastly ammonia. When a green color is no longer pro- duced, it is known that all the quinine has been removed. When the operation is well conducted, about 150 grammes of chloroform suffice for this purpose. The menstruum re- tained by the mass is displaced by water, and the whole of the chloroform solution is either distilled or evaporated to -dryness. To separate the alkaloids from the residue, it is treated several times in the cold with diluted sulphuric acid (1 to 10). 10 to 12 cubic centimetres are sufficient. This i solution thrown upon a moistened filter passes through color- | less, and free from resinous matter ; it is raised to the boil- | ing-point, and ammonia cautiously added, so as to leave I the liquid with a slightly acid reaction. The sulphate of j ammonia thus formed appears to prevent the mother-liquors from retaining sulphate of quinine in solution. All the quinine crystallizes out in the state of sulphate. After some time it is collected on a double filter, the mother- liquors displaced b}^ a little water, and the crystals dried and weighed. It is preferable to dry completely at 100° I C., and after weighing in this state to add the 12 per cent, j of water which is lost by this treatment. The other alka- j loids retained in the mother-liquors are separated by pre- i cipitation. | Of the Citrate of Iron and Quinia (Fend et Quinise j Citras^ B. P. and U. S. P.) it is officially stated that ‘‘ fifty grains dissolved in a fiuidounce of water and treated wdth j a slight excess of ammonia give a white precipitate which, | when collected on a filter, washed, and dried (at 260 F.) t weighs eight grains. The precipitate is almost entirelj'' ' soluble in two or three fluidrachms of pure ether,’’ and the ethereal solution set aside for twelve hours in a small well- corked bottle yields no crystalline deposit (of quinidia). MORPHIA. The official process for the estimation of this alkaloid in opium is conducted in the following manner: — Take of opium 100 grains, slaked lime 100 grains, dis- MORPHIA. 533 tilled water 4 ounces. Break down the opium, and steep it in an ounce of the water for twenty-four hours, stirring the mixture frequently. Transfer it to a displacement- apparatus, and pour on the remainder of the water in suc- cessive portions, so as to exhaust the opium by percolation. To the infusion thus obtained, placed in a flask, add the lime, boil for ten minutes, place the undissolved matter on a filter, and wash it with an ounce of boiling water. Acid- ulate the Altered fluid slightly with diluted hydrochloric acid, evaporate it to the bulk of half an ounce, and let it cool. Neutralize cautiously with solution of ammonia, carefully avoiding an excess ; remove by filtration the brown matter which separates, wash it with an ounce of hot water, mix the washings with the filtrate, concentrate the whole to the bulk of half an ounce, and add now solu- tion of ammonia in slight excess. After twenty-four hours collect the precipitated morjfliia on a weighed filter, wash it with cold water, and dry it at 212° F. It ought to weigh at least from six to eight grains. Of Hydrochlorate of Morphia it is stated that “ twenty grains of the salt dissolved in half an ounce of warm water, with ammonia added in the slightest possible excess, give on cooling a crystalline precipitate which, when washed with a little cold water and dried by exposure to the air, weighs 15.18 grains.’^ Testing Opium , — Professor Schneider has proposed, in the 6th revised edition of the Pharmacopoeia Austriaca, the following method for testing the quality of opium. Ten grammes of previously dried and powdered opium are treated with a mixture of 150 grammes of distilled water, to which 20 grammes of pure hydrochloric acid, sp. gr. 1.12, are added ; the residue, after extraction, should not exceed 4.5 grammes w^eight ; to tlie acid fluid 20 grammes of com- mon salt are added, and the precipitate thereby caused is collected, after tw'enty-four hours, on a filter, and the lat- ter washed with a solution of common salt; to the filtrate ammonia is added, and the. fluid left standing again for twentj’-four hours ; the crj^stals which have separated are collected, redissolvQd in acetic acid, and precipitated with ammonia; the precipitate so obtained is washed, dried, and weighed; its weight should not be less than 1 gramme. 45 * 534 QUANTITATIVE ANALYSIS. SUGAR. The qualitative test of sugar, hy means of an alkaline copper solution (vide p. 347), may be applied in the esti- mation of sugar in sacchariferous substances. Process, — 34.64 grammes of pure dry crystals of ordi- nary sulphate of copper are dissolved in about 250 c. c. of distilled water, 173 grammes of pure crystals of the double tartrate of potassium and sodium are dissolved in 480 c. c. of solution of caustic soda of sp. gr. 1.14. The solutions are mixed and water added to one litre. 100 c. c. of this solution represent 3.464 grammes of sulphate of copper, and correspond to 0.5 of a gramme of pure anhydrous grape-sugar, 0.475 of cane-sugar, or 0.45 of starch. It must be preserved in a well-stoppered bottle to prevent absorp- tion of carbonic acid, and be kept in a dark place. If it give a precipitate on boiling, a little solution of soda may be added in making experiments. Dissolve 0.475 of pure dry powdered cane-sugar in about 50 c. c. of water, convert into grape-sugar by acidulating with sulphuric acid, and boiling for an hour or two, neu- tralize with carbonate of sodium, and dilute to 100 c. c. Place 10 c. c. of the copper solution in a small flask, dilute with three or four times its bulk of water, and gently boil. Into the boiling liquid drop the solution of sugar from a | burette, one cubic centimetre, or less, at a time, until, after standing for the precipitate to subside, the supernatant liquid has just lost its blue color; 10 c. c. of the solution of the sugar should be required to produce this effect, = 0.475 of cane-sugar or 0.5 of grape-sugar. Experiments on pure cane-sugar must be practised until accuracy is at- tained ; syrups, diabetic urine, and saccliarated substances containing unknown quantities of sugar may then be ana- l3^zed. Starch is converted into grape-sugar by gentle ebullition with dilute acid for eight or ten hours, the solution being finall}^ diluted so that one part of starch, or rather sugar, ! shall be contained in about 150 of water. ! Saccharimetry . — A generic term for certain volumetric i operations undertaken with the view of ascertaining the j quantity of sugar present in any matter in which it may j be contained. j Sacchariinetiy is frequently performed upon common j syrup (Syrupiis,^ B. P.) and solutions which are known to ! SUGAR. 535 contain nothing but cane- (ordinary) sugar, the object being merely to ascertain the amount present. In such a case it is only necessary to take the specific gravity of the liquid at 60° F., and then refer to a previously prepared Table of densities and percentages. Specific Sugar Specific gravity. per cent. gravity. 1.007 . . 1.8 1.100 1.014 . . 3.5 1.108 1.022 . . 5.2 1.116 1.029 . . 7.0 1.125 1.036 . . 8.7 1.134 1.044 . . 10.4 1.143 1.052 . . 12.4 1.152 1.060 . . 14.4 1.161 1.067 . . 16.3 1.171 1.075 . . 18.2 1.180 1.083 . . 20.0 1.190 1.091 . . 21.8 1.199 Sugar Specific Sugar per cent. gravity. per cent. 23.7 1.210 . . 46.2 25.6 1.221 . . 48.1 27.6 1.231 . . 50.0 29.4 1.242 . . 52.1 31.5 1.252 . . 54.1 33.4 1.261 . . 56.0 35.2 1.275 . . 58.0 37.0 1.286 . . 60.1 38.8 1.298 . . 62.2 40.6 1.309 . . 64.4 42.4 1.321 . . 66.6? 44.3 1.330 (B.p.) 66.6? The sp. gr. may be taken by an hydrometer, technically termed a mccliarometer, (The above spec, gravs. = 1° to 35° Baume.) If a liquid contains other substances besides cane-sugar, the test of specific gravity is of little or no value. Advan- tage may then be taken of the fact that syrup causes right- handed twisting of a ray of plane polarized light to an extent exactly proportionate to the amount of sugar in solu- tion. The saccharine fiuid is placed in a long tube having opaque sides and transparent ends ; and a ray of homoge- neous light, polarized by refiection from a black-glass mir- ror or otherwise, is sent through the liquid and optically examined by a plate of tourmaline, NicoPs prism, or other polarizing eyepiece. Attached to the eyepiece is a short arm which traverses a circle divided into degrees. The eyepiece and arm are previously so adjusted that when the ray is no longer visible the arm points to the zero of the scale of degrees. The saccharine solution, however, so twists the ray as to again render it visible ; and the num- ber of degrees which the eyepiece has to be rotated before the ray is once more invisible is exactly proportionate to the strength of the solution. The value of the degrees having been ascertained by direct experiment and the results tabulated, a reference to the Table at once indicates the percentage of sugar in the liquid under examination. 536 QUANTITATIVE ANALYSIS. Grape-sugar also possesses the property of dextro-rotation, but less powerfully than cane-sugar ; moreover the former variety does not, like cane-sugar, suffer inversion of the direction of rotation on the addition of hydrochloric acid to its solution — an operation that furnishes data for ascer- taining the amounts of cane- and of grape-sugar, or of crys- tallizable and non-ciwstallizable sugar, present in a mixture. In using the polariscope-saccharometer, it is convenient to employ tubes of uniform size, and always to operate at the same temperature. ALCOHOL. Mulder^s process for the determination of the amount of alcohol in wines, beer, tinctures, and other alcoholic liquids containing vegetable matter is as follows : Take the spe- cific gravity and temperature of the liquid, and measure off a certain quantity (100 cubic centimetres); evaporate to one-half or less, avoiding ebullition in order that parti- cles of the material may not be carried away by the steam. Dilute with water to the original bulk, and take the specific gravity at the same temperature as before. Of the figures representing this latter specific gravity, all over 1.000 show to what extent dissolved solid matter aflfected the original specific gravity of the liquid. Thus, the specific gravity of a sample of wine at 15°. 5 C. is 0.9951 ; evaporated till all alcohol is removed and diluted with water to the original bulk, the specific gravity at 15°.5 C. is 1.0081: 0.0081 re- presents the gravitating effect of dissolved solid matter in 0.9951 parts of original wine. 0.0081 subtracted from 0.9951 leaves 0.987, which is the specific gravity of the water and alcohol of the wine. On referring to a Table of the strengths of diluted alcohol of different specific gravi- ties (p. 550), 0.987 at 15°.5 C. is found to indicate a spirit containing 8 per cent, of real alcohol. If the foregoing operation be conducted in a retort, the liquid being boiled and the steam carefully condensed, the distillate, diluted with water to the original bulk of wine operated on, will still more accurately represent the amount of water and alcohol in the wine — its specific gravity showing the per- centage of real alcohol present. DIALYSIS. 537 DIALYSIS. Dialysis (from 6ta, dia^ through, and lusis^ a loosing or resolving) is a term applied by Graham to a process of analysis by diffusion through a septum. The apparatus used in the process is called a dialyzer^ and is constructed and employed in the following manner. The most conve- nient septum is the commercial article known as parchment paper^ made by immersing unsized paper for a short time in sulphuric acid ; it is sold by most dealers in chemical apparatus. A piece of this material is stretched over a gutta-percha hoop, and secured by a second external hoop. Dialyzers of useful size are one or two inches deep and five to ten inches wide. Liquids to be dialyzed are poured into the dialyzer, which is then fioated in a flat dish containing distilled water. The practical value of dialysis depends upon the fact that certain substances will diffuse through a given septum far more rapidly than others. Uncry stallizable bodies diffuse very slowly. Of such matters as starch, gum, albumen, and gelatine, the last named is perhaps least diffusive ; hence substances of this class are termed colloids^ or bodies like collin^ which is the soluble form of gelatine. Substances which diffuse rapidly are mostly crystalline ; hence bodies of this class are termed crystalloids. Solutions of two parts of the following named substances in 100 parts of distilled water were dialyzed b}^ Graham for twenty-four hours. The amounts of each substance which passed through the septum bore the following relations to one another ; — Chloride of sodium 1000 Ammonium 847 Theine 703 Salicin 503 Cane-sugar 472 Amygdalin 311 Extract of logwood 168 Catechu 159 Extract of cochineal 51 Gallo-tannic acid 30 Extract of litmus 19 Purified caramel 5 538 DIALYSIS. Ten-per-cent, solutions, under similar circumstances, the following results : — Gum Arabic 4 Starch -sugar 266 Cane-sugar 214 Glycerine 440 Alcohol 476 Chloride of sodium 1000 The phenomena of dialysis show that ciystalloids are superior to colloids in affinity for water. If a solution of chloride of sodium be placed at the bottom of a jar, and covered by a hot solution of gelatine of sufficient strength to solidify on cooling, the chloride of sodium will diffuse up into the solid jell}^, because the water of the solid jelly has a greater affinity for the salt than it has for the gelatine. The solid jelly may obviously be reduced in thickness, and saline liquids placed above it ; indeed the conditions would then be still more favorable for diffusion. Replace the stratum of jelly hy a permanent colloid, suCh as parchment paper ; the result is the same, but the permanent character of the septum admits of its practical application. Further researches on dialysis will probably throw much light on several important points in connection with phy- siological chemistry; for there is little doubt that alimentary matter passes through the cell-walls of animals and plants hy this process. QUESTIONS AND EXERCISES. 1055. Carbonate of potassium is said to lose 16 per cent, of water ! on exposure to a red heat ; give the details of manipulation observed ' in verifying this statement. | 1056. Write a few paragraphs descriptive of the process of ulti- mate organic analysis. 1057. In what forms are carbon, hydrogen, and nitrogen weighed in quantitative analysis ? 1058. In the combustion of .41 of a gramme of sugar, what weights of products will be obtained ? — Ans. .632 of carbonic acid gas tCO J and .237 of water (II. 2 O). 1059. Describe De Vry’s process for the assay of commercial quinia. 1060. Give the official method for the estimation of morphia in opium. CONCLUSION. 539 1061. Mention the operations necessary for the estimation of the proportion of sugar in saccharated carbonate of iron, or in a speci- men of diabetic urine. 1062. What is understood by saccharimetry ? 1063. Give two processes for the estimation of the percentage of alcohol in tinctures, wines, or beer. 1064. Define dialysis. Conclusion. Detailed instructions for the quantitative analysis of potable water, articles of food, general technical products, special minerals, soils, manures, air, illuminating agents (including solid fats, oils, spirits, petroleum, and gas), dyes, and tanning-materials, would scarcely be in place in this volume. The course through which the reader has been conducted wdll, it is hoped, have taught the principles of the science of chemistry, and given special knowledge concerning the applications of that science to medicine and pharmacy, as well as have imparted sufficient manipulative skill to meet the requirements of manufacture or analysis. The author would venture to suggest that this knowledge be utilized, not only in the way of personal advantage, but in experi- mental researches on chemical subjects connected with therapeutics and pharmacy. The discovery and publica- tion of a new truth, great or small, is the best means whereby to aid in advancing the calling in which we may be engaged, benefit our fellow creatures, and unveil the laws of the Creator of all things. APPENDIX TABLE OF OFFICIAL TESTS FOE IMPURITIES IN PHAEMACOPCEIAL PREPARATIONS * Name of Preparation. Impurities. Tests. Acacise Gummi . . . Acelum r I Acidum Aceticum . I L Acid. Acetic. Glaciate . Acidum Boracicum. . Acidum Carbolicum | r Acidum Citricum . ^ I Acidum Gallicum . . r Acidum Hydrochlo- J ricum . \ Acidum Hydrocya- f nicum Bilutum . ) r I Acidum Nitricum. . Acidum Oxalicum . . r Acidum Phosphor!- ^ cum Dilutum . Starch More than one thousandth of Sulphuric acid . Traces of Lead or Copper Sulphuric acid . . . . Hydrochloric acid . . . Sulphurous acid . . . . Sulphurous acid . . . . Alkaliue salts Creasote Traces of Copper or Lead Tartaric acid Tartaric acid Sulphuric acid . . . . Mineral matter . . . . Tannic acid Sulphuric acid .... Arsenic Sulphurous acid . . * . Sulphuric acid .... Hydrochloric acid . . . Mineral matter .... Sulphuric acid . . . . Hydrochloric acid . . . Mineral matter .... Lead or Platinum . . . Sulphuric acid .... Hydrochloric acid . . . Metaphosphoric acid . . Nitric acid Phosphorous acid . . . Iodine Quantitative analysis . . Sulphuretted Hydrogen . Chloride or Nitrate of Ba- rium Niirate of Silver . . . Nascent Hydrogen . . . Nascent Hydrogen . . . Insolubility in Alcohol . Oxidation, etc. See Crea- sotum Sulphuretted Hydrogen . Acetate of Potassium . . Excess of Lime-water . . Chloride or Nitrate of Ba- rium Incineration (Isinglass) Gelatine . . . Chloride or Nitrate of Ba- rium Sulphuretted Hydrogen, Copper Nascent Hydrogen . . , Chloride or Nitrate of Ba- rium Ppt. by Nitr. silver, insol. in nitric acid .... Evaporation and ignition. Chloride or Nitrate of Ba- rium Nitrate of Silver . . . . Incineration Sulphuretted Hydrogen . Chiwide or Nitrate of Ba- rium Nitrate of Silver and Nitric acid Albumen Ferrous Sulphate and Sul- phuric acid Corrosive sublimate . . Page. 245 519 197 277 240 274 274 29(5 392 197 28 291 277 86 317 277 148 274 277 240 86 277 240 86 229 277 240 311 256 313 * The manipulations necessary to be observed in testing for impurities will be found described in the paragraphs treating of those substances. The Table also in- cludes references to processes for ascertaining deticiency in strength of official articles. The other “characters and tests” of pharmacopoeial compounds have been given in connection with the respective synthetical and analytical reactions. 46 542 APPENDIX Name of Preparation. Impurities. Test. Page. r Mineral matter . . . . Evaporation and ignition. 86 Acidiim Sulphuri- J Nitric acid Ferrous Sulphate . . . 256 Arsenic or Lead . . . . Sulphuretted Hydrogen . 197 Acidum Sulpharosam. Sulphuric acid . . . . Chloride or Nitrate of Ba- rium 277 Acidum Tannicum . . Mineral matter . . . . Incineration 86 r Metallic matter, as Lead . Sulphuretted Hydrogen . 197 1 Oxalic acid Sulphate of Calcium . . 282 Acidum Tartaricum 1 Calcium (tartrate or sul- Oxalate of Ammonium . 98 phate). L Mineral matter . . . . Incineration 86 Aconitia Mineral matter . . . . Incineration 86 Adeps prfeparatus . | Chloride (of sodium) . . Starch (flour) Nitrate of Silver . . . . Iodine 240 24.5 JEther Alcohol Boiling point, sp. gravity. 378 JEther Purus . . . Alcohol, Water . . . . Specific gravity . . . . 378 Alcohol .... 1 Resin or oil Opalescence on dilution . 375 Water Anhydrous Sulphate of Copper 168 Alcohol Amylicum . . Other spirituous matter . Boiling point, sp. gravity. 389 Alum Iron (sulphate) . . . . Yellow or red prussiate . 136 Ammonii Benzoas . . Fixed salts Non-volatility . . . . 85 r Free Bromine Odour 241 Ammonii Bromidum-^ Iodide (of Ammonium). . Chlorine water and starch 245 1 General Quantitative analy8is(446) 493 f Fixed salts Sulphate (of Ammonium). Non-volatility . . . . Chloride or Nitrate of Ba- 85 Ammonii Carbonas rium 277 Ammonii Chloridum . Chloride (of Ammonium). Nitrate of Silver .... 240 Fixed salts Non- volatility . . . . 85 Ammonii Nitras . | Sulphate (of Ammonium). Chloride of Barium . . . 277 Chloride (of Ammonium). Nitrate of Silver .... 240 Amylum . . . . | Alkaline matter . . . . Red Litmus 83 Acid matter Blue Litmus 83 Antimonium Nigrum . Silica Insolubility in HCl . . . 315 Antimonii Oxidum Higher oxides of antimony Insolubility in sol. of acid tartrate of potassium 156 Antimonium Tartara- General Quantitative analysis . . 509 tum. Sn) Aqua Aurantii Floris . Metallic matter (Pb, Cu, Sulphuretted Hydrogen . 229 r Fixed salts Evaporation and ignition. 86 Tin, Lead, or Copper . . Sulphuretted Hydrogen . 229 Calcium salts Oxalate of Ammonium . 98 Aqua Destillata . . Chlorides Nitrate of Silver . . . . 240 Sulphates Chloride of Nitrate of Ba- rium 297 Carbonates Lime-water 280 Argenti Nitras . . . r Other nitrates, etc. . . . Metallic silver .... Quantitative analysis, etc. Effervescence with Nitric 513 Argenti Oxidum . acid 191 L General Quantitative analysis . . 513 Argentum Purificatum Copper Ammonia to the Nitric so- lution 169 Atropia Mineral matter .... Incineration 86 Atropiae Sulphas . , Mineral matter .... Incineration 86 Balsamum Peruvi- < .Fixed oil Immiscibility with Alcohol 402 anum ^ Alcohol Non-diminution of volume when mixed with water 374 Beberia3 Sulphas . . Mineral matter .... Incineration 86 Nitrates (of Bismuth or Sulphate of Indigo . . . 258 Bismuth! Carbonas Ammonium). Lead (carbonate) . . . Diluted Sulphuric acid . 189 1 Chloride (oxychloride of Nitrate of Silver . . . . 240 1 Bismuth! Subnitras | bismuth). Lead (oxynitrate) . . . Diluted Sulphuric acid . 179 Chlorides (oxychloride of Nitrate of Silver . . . . 240 bismuth). APPENDIX 543 Name of Preparation. Impurities. Tests. Page. Bismuthum Piirifica- Copper Ammonia to Nitric solut’n 169 turn. r General Specific gravity (465) and Bromum boiling point 449 L f Iodine Zinc (iodide) Starch Potash in excess, then 24.5 Cadraii lodidum . Sulphydrate of Ammo- nium ....... 222 1 General Quantitative analysis . . 514 Calcii Carbonas Prse- f Alumina, Oxide of Iron, Sacc. solution of lime to and Phosphates. sol. in nitric acid . . . 92 cipitata . . • Chlorides Nitrate of Silver . . . . 240 Hypochlorite of Calcium Hydrochloric acid . . . 260 Calcii Chloridum . | Carbonic acid Lime-water 280 r Carbonates (of Calcium) . Effervescence with acids . 280 Calcii Phospbas. . Alumina Solution of potash . , . 118 Sand Insolubility in acid . . . .815 Calx 1 Carbonate of Calcium . . Effervescence with acids . 286 Alumina, Oxide of Iron, Sacc. sol. of lime, to sol. etc. in acids 92 Calx Chlorata . . General Quantitative analysis . . 495 Cambogia Starch Iodine (Green) . . . . 245 Campliora Fixed salts Non-volatility . . . . S3 Carbo Aniraalis Purifi- Earthy salts Incineration (by help of 86 catus. red ox. of mercury) . . Carbo Ligni . . . . More than 2 per ct. of ash Incineration 86 . Catechu Pallidum . . Starch Iodine 24.5 Cera Alba Soft Fats Melting-point 451 r Soft Fats Melting-point 451 Cera Flava . . . ^ Resin Solubility in Alcohol . . 410 L Flour tine. Iodine 245 r Carbonates and other oxa- Ash sol. in acids with ef- 1 Cerii Oxalas . . . lates. fervescence 280 Alumina Insolubility of Hydrate in Ammonia 203 L General More or less than 48 per cent, of ash 203 Cetaceum Soft Fats Melting-point 451 Chloral | Chlorine Nitrate of silver .... 388 General Quantitative analysis . . 388 r General Specific gravity .... 450 Chloroform . . . ^ Hydrocarbons . . Sulphuric acid .... 386 L Non-volatile matter . . Residue on evaporation . 86 Copaiba o o Gelatinization at 270° F. . Incomplete solubility in 412 Benzol 412 ( Oxidation 1 Non-volatility at 212° F. 392 Creasotum .... Carbolic acid ....-<( Dextro-rotation of polar- 1 ized ray 392 Cupri Sulphas . . . L Crystallization on cooling 392 Iron (ferrous sulphate) . Nitric acid and ammonia 137 Elaterium . . . . | Carbonates (chalk) . . . Effervescence with acids . 280 General Quantitative analysis . . 368 Pel Bovinum Purifica- Mucus, crude bile . . . Incomplete solubility in tura. spirit . 411 Sulphate of (sodium) . . Chloride or Nitrate of Ba- Fern Arsenias . . rium 297 1 General Quantitative analysis . . 492 Ferri Carbonas Sac- f Sulphate (of ammonium) . Chloride or Nitrate of Ba- 297 charata . , . . rium General ... ... Quantitative analysis . . 492 f Tartrate (of iron and am- Ebullition with potash and Ferri et Ammonii J Citras . . . . j monium) saturation with Acetic acid (=KHC 4 H^ 06 ) . . 287 General Quantitative analysis . . 507 L Potassium or Sodium, salts Alkalinity of ash . . . 83 544 APPENDIX Name of Preparation, Impurities, Test. Page. Ferri et Quinife Ci- f Potassium or Sodium, salts Alkalinity of ash . . . 83 General Quantitative analysis . . 507 1 1 ith ^ Alkaloids other than Qui- Insolubility of ppid. alka- nia. loid in ether 344 Ferri Oxidum Mag- ^ Metallic iron Effervescence with acids . 134 neticam . ( General Quantitative analysis . . 492 Ferri Peroxidum ( Humidum . . . J Ferrous hydrate .... Ferric oxyhydrate . . . Red prussiate to acid so- lution Insolubility in cold dil. 136 Hydrochloric acid . . 129 Arsenicum (ferri arsenias) Slip of Copper in acid so- Ferri Phosphas . . < lution 148 General Quantitative analysis . . 492 Ferri Sulphas . . f Ferric oxysulphate . . Insolubility in Water . . 122 Ferri Sulphas Gra- ! Ferric compounds . . . Ppt. ofSiu aqueous sol. nulata . . . . [ by HgS L Copper, etc Sulphuretted Hydrogen . 229 Ferrum Kedactum . . Less than 50 per cent. . Quantitative analysis . . 508 Ferrous compounds . . Red prussiate to acid so- Ferrum Tartaratum Ammoniacal salts . . . lution Soda 136 82 L General Quantitative analysis . . 507 Glycerina General . Specific gravity . . . . 394 Hydrargyri lodidum Fixed salts Non-volatility . . . . 184 Rubrum. Hydrargyri lodidum Red Iodide Insolubility in ether . . 172 Viride. Hydrargyri Oxidum ) Flavum . . . . ^ Fixed Salts Non-volatility . . . . 184 Hydrargyri Oxidum ^ Fixed Salts Non-volatility . . . . 184 Rubrum . ... ( Nitrates (of mercury) . . Orange vapor on heating in a tube 179 Hydrargyri Subchlo- ^ Corrosive Sublimate . . Treatment with ether . . 178 ridum ( Fixed salts Non-volatility . . . . 184 Hydrargyri Sulphas Fixed salts Non-volatility . . . . 184 Hydrargyrum . . . Fixed meials (Pb, Sn, Zn, Non-volatility . . . . 184 Bi, Cu). Hydrargyrum Ammo- Fixed salts Non-volatility . . . . 184 niatum. Hydrargyrum cum Mercuric oxide .... Stannous chloride to sol. Greta. in HCl 183 r Fixed salts Non-volatility . . . . 243 lodum ^ Cyanide of Iodine . . . Physical characters . . 243 1 General Quantitative analysis . . 494 Jalapse Resina . . , Resin Solubility in Turpentine . 369 Limonis Succus . . . Deficiency of Citric acid . Quantitative analysis . . 290 Liquor AmmOnise . . General . . . . . | Specific gravity • . . . Quantitative analysis . 465 476 General impurity or defi- Specific gravity (449) and ciency. Quantitative analysis . 476 Carbonate of Ammonium. Lime-water Calcium .salts(chloride etc. ) Oxalate of Ammonium . 98 Liquor Ammonise ^ Fortior . . . . ^ Iron salts (ferrous hy- drate). Sulphydrate of Ammo- nium Sulphur salts (AmHS) . . Ammonio-sulphate of Cop- per 272 Chloride of Ammonium . Sulphate of Ammonium . Nitrate of Silver to acidi- fied sol Chloride of Barium to aci- 240 dified sol Liq. Antimonii Chlo-' ridi 489 Liq. Arsenicalis . . Li(i. Arseuici Hy- General impurity or de- ^ 1 Specific gravity . . . j Quantitative analysis . | 1 509 drochloricus . . I Liq. Bisinuthi et Am- | flciency ^ 489 1 mouii Cit. . . . J 1 1 510 1 APPENDIX 645 Name of Preparation. Impurities. Test. Page. Liq. Calcis . . . Deficiency iu strength . . Quantitative analysis . . 478 Liq. Calcis Chloratfe' Liq. Calcis Saccha- ratus General impurity or de- ^ Specific gravity .... 466 r ficiency ( Quantitative analysis(o07) 478 r General quality . . . . Specific gravity .... 465 Liquor Chlori . . Fixed matter . . . . Kesidue on evaporation . SO Deficiency in strength . . Quantitative analysis . . 495 Liq. Ferri Perchlo-'^ ridi Fort. . . r Ferrous salts Red Prussiate 1.37 Liq. Ferri Perni- ! tratis . . . . j General impuritv or de- ^ Specific gravity . . . . 465 ficiency ( Quantitative analysis . . 507 Liq. Ferri Persul- { t. phaiis . . . J Liq. Hydrargyri Nit. Deficiency in strength Specific gravity .... 466 Acid Mercurous salts (nitrate) . Hydrochloric acid . . . 183 Liq. Litliii Efferves- General impurity or defi- Quantitative analysis, etc. 201 cens ciency. Liq. Magnesii Car- ^ bonatis . . . . ( Other magnesian salts Bitter taste (MgClaMgSO^). 101 General impurity or defi- Quantitative analysis . . 505 ciency. Specific gravity . . . . Liq. Plumbi Subace- General impurity or de- < 466 latis ficiency ^ Quantitative analysis . . 478 ' General impurity or de- J Specific gravity . . . . 466 ficiency ( Quantitative analysis . . 478 Carbonate(ofpotassium) | Effervescence with acids . Lime-water 277 280 Calcium salts Oxalate of Ammonium 98 Liquor Potassse . . - f Silica. . . Insol.iu acid after evap. etc. 315 1 Sulphates . Chloride of Barium to acid More than < traces of | Chlorides . sol Nitrate of silver to acid 276 1 sol 210 I^Alumina. . Ammonia to acid sol. . . 117 Liq. Potassse Effer- \ Deficiency in strength . . Quantitative analysis . . 478 vesceus . . . . i i Bicarbonate of sodium . . Tartaric acid, etc, . . . 500 r General impurity or de- ^ Specific gravity . . . . 466 ficiency ( Quantitative analy.sis . , 478 Calcium salts Oxalate of Ammonium 98 Liquor Sodse . . . - Carbonate (of sodium) . | Effervescence with acids . Lime-water 280 280 f Silica. . . Insol. in acids after evap 315 More than J Sulphates . traces of , Chlorides . BaClg to acid sol. . . . 276 AgN 03 fo acid sol. . . . 210 1 L [^Alumina. . Ammonia to acid sol. . . 117 1 r Salts of Potassium or Am- Perchloride of Platinum 1 Liquor Soda3 Chlo-J ratse j 1 1 monium General impurity or defi- to acid sol Quantitative analysis (65) 83 491 i ciency. Calcium salts Oxalate of Ammonium . 98 Liq Sodse EfFeryescens Deficiency in strength . . Quantitative analysis . 478 1 r General impurity or defi- Quantitative analysis . . 201 Lithii Carbonas . . ^ 1 ciency. Calcium salts Oxalate of Ammonium, etc. 201 1 L Alumina Lime-water, etc 201 Litbii Citras . . . Deficiency in strength . . Quantitative analysis . . 201 Carbonate (of magnesium) Effervescence with acids . 102 Magnesia . . . . ^ Magnesia Levis . . Calcium (hydrate or car- bonate). Sulphates (of magnesium Oxalate of Ammonium to acet sol Chloride of Barium to acid 98 or sodium). sol 276 Alumina Ammonia to acid sol. . . 117 Sulphates (of magne.sium Chloride of Barium to acid or sodium). solution 276 Magnesii Carbonas Calcium (carbonate) . . Oxalic acid to Ammonia- Magnesii Carb. Le-^ cal solution 98 VIS Iron, Lead, etc Sulph. hydrogen to sol. in »• acid excess of Ammon. 229 General impurity or defi- Quantitative analysis . . 505 ciency. 40 * 546 APPENDIX Name of Preparation. Impurities. Test. Page. r Calcium (sulphate) . . . Oxalate of Ammonium . 98 Magnesii Sulphas . ^ Iron (sulphate) .... Chlorinated Lime or Soda 100 L Geueral impurities . . . Quantitative analysis . . 505 Manna Deficiency of mannite . . Quantitative analysis . . 361 Mel Starch (flour) Iodine 245 Morphise Hydrochloras r General impurities . . . Quantitative analysis . . 533 Fixed oil Permanent greasy stain 1 Olea Destillata . . Alcohol on paper Loss in volume on shak- 1 ing with water . . . . Opium Deficiency in morphia Quantitative analysis . . 532 Plumbi Acetas . . . General Quantitative analysis . . 478 r Sulphate of Lead or Ba- Insolubility in Acetic acid Plumbi Carbonas . ^ L rium or Silicates . . . Calcium (chalk) .... (190, 88, 172) Oxal. Ammonium after re- 215 moving Lead .... 98 Plumbi Oxidum . | Carbonates Effervescence with acids . 280 Copper (oxide) . . . . Ammonia to acid solution 169 r Potassa Caustica . More than fCtloride. . traces of | Sulphates . Nitrate of silver to acid solution Chloride of Barium to acid 216 1 solution 276 L General impurities (water Quantitative analysis . . 478 Potassa Sulphurata . etc.). Excess of Carbonate or More than 25 per cent, in- Sulphate sol. in spirit 57 r Iron and other metallic Sulphydrate of Ammo- Potassii Acetas . . 4 impurities nium 229 1 Carbonate of Potassium . Effervescence with acids ; 280 alkalinity; insolubility in spirit 57 Potassii Bicarbonas . General Quantitativeanalysis . . 478 r Free bromine Odor 211 Potassii Bromidum { Iodide (of potassium) . . Chlorine-water and starch 216 L General Quantitative analysis (487) 515 r fSilicate . . Insol. in acid after evap. 1 Potassii Carbonas . More than ! c i i * traces of ^ Sulphal, . elc Chloride of Barium to acid solution 276 1 (.Chloride Nitr. of Silver to acid sol. 210 L General • Quantitative analysis . . 478 Potassii Chloras . | Chloride (of potassium) . Nitrate of Silver . . . . 240 Calcium (chloride) . . . Oxalate of Ammonium 98 Potassii Citras . . . General Quantitativeanalysis . . 481 Potassii Ferridcyani-. Ferrocyanide (of potas- Ferric salt dum sium). r lodaie (of potassium) . . Tartaric acid and starch . 62 Potassii lodidum . ■{ Chloride (of potassium) . Nitrate of Silver, etc. . . 210 L Carbonate (of potassium). Sacc. solution of Lime . . 92 Potassii Nitras . . | Sulphate (of potas^ium) . Chloride of Barium . . 276 Chloride (of potassium) . Nitrate of Silver . . . 240 Potassii Permanganas Geueral Quantitativeanalysis. 493 Potassii Sulphas . | Acid Sulph. of Potassium Test-paper 83 Calcium (sulphate). . . Oxalate of Ammonium .i 98 Potassii Sulphis . . Hyposulphite (of potas- sium). Sulphuric acid . . . . 308 Potassii Tartras . ^ Potassii Tartr, Acida ] General Quantitative analysis . . 481 Quinife Sulphas . . j Salicin General Sulphuric acid .... Quantitative analysis . . 370 529 Rhei Radix . . . . Turmeric Boracic acid 297 Santoninum . . . | Mineral matter . . . . Incineration 86 Earthy soaps, etc. . . . Insolubility in spirit . . 401 Sapo Durus . . . | Oil Oily stain to paper . . . 401 Potassium compounds Deliquescence of ash . . 401 Sapo Mollis ... 1 Earthy soaps, etc. . . . Insolubility in spirit . 1(11 Oil Oily stain to paper . . . 401- APPENDIX 54t Name of Preparation Impurities. Test. Page. Resin of guaiacum . . . Inner surface of Potato- Scammonise Kesina ■< paring .369 1 Resin of Jalap . . . . Insolubility in ether . . 369 Carbonate (of calcium and EfiTervescence with acids . 280 Scammonium . . magnesium). Starch (flouij Solution of Iodine . . . 245 Sinapis Starch (flour) Solution of Iodine . . . 245 [ More than ^ Chloride . . Nitr. of Silver to acid sol. 210 Soda Caustica . . traces of ^ Sulphate . . Chloride of Barium to acid sol 276 1 General impurities (water Quantitative analysis . . 478 etc ). Soda Tartarata . . General Quantitative analysis . . 481 r Acid or alkaline matter . Test-paper 83 Soda Acetas . . . Sulphates (sodium or cal- cium). Chloride of Barium to acid sol 276 1 Chlorides (sodium or cal- Nitrate of Silver to acid cium). sol 240 r Excess or deficiency of Quantitative analysis . . 487 Sodii Arsenias . . ^ water of crystallization . L General Quantitative analysis . . 487 r Neutral Carbonate (of so- Mercuric chloride . . . 184 1 dium). Sodii Bicarbonas . •! More than < Chloride . . traces of ^ Sulphate . . Nitr. of Silver to acid sol. Chloride of Barium to acid •240 1 sol 276 L General Quantitative analysis . . 478 Sodii Boras . . . . General Quantitative analysis . . 478 r Excess or deficiency of Quantitative analysis . . 525 Sodii Carbouas . . ^ 1 water of cryst. etc. More than ^ Chlorides . . traces of ^Sulphates. . Nitr. of Silver to acid sol. Chloride of Barium to acid 240 sol 276 Sodii Hyposulphis General Quantitative analysis . . 489 Sodii Nitras . . . | Chloride (of sodium) . . Nitrate of Silver . . . . 240 Sulphate (of sodium) . . Chloride or Nitrate of Ba- rium 276 r More than trace of Sul- Chloride or Nitrate of Ba- Sodii Phosphas . . phate. rium to acid sol. . . . 276 L Deficiency or excess of Quantitative analysis . . 525 water of cryst. Sodii Sulphas . . Ammonium salts . . ) Ferric salts . . . . ^ General Solut’n of potash heated | Quantitative analysis . . 81 137 519 L Excess or deficiency of Quantitative analysis . . 525 water of cryst. Test-papers Insolubility in spirit . . Sodii Valerianas . . Free soda or carbonate | 83 321 r General Specific gravity . . .. . 466 More than trace of acid . EfiTervescence with bicar- Spiritus iEtheris Ni-J irosi j Free acid bonate of sodium . . . More than “feeble” effer- vescence with bicarbo- 280 1 nate of sodium .... 280 1 Deficiency of nitrite of Quantitative analysis . . 380 Spiritus Aramouio- 1 [ethyl. Arornat Spiritus Chloroformi j General Specific gravity .... 465 , r General (excess of water) Specific gravity .... 465 Spiritus Rectificatus-^ Resin or oil Opalescence on dilution . 375 1 More than traces of fusil Nitrate of Silver . . . . 487 oil, etc. Spiritus Tenuior . . General (excess of water). Specific gravity .... 373 Strychuia . , . . | Brucia 248 Mineral matter .... Incineration 86 Sulphur Prsecipita - ) turn ^ Sulphate of calcium . Appearance under micro- scope 271 L Residue on ignition . .| 271 548 APPENDIX Name of Preparation Impurities. Test. Page. r Earthy matter .... Incineration 86 Sulphur Sublima- . Trace of Acid (H 2 SO 4 or Litmus-paper 83 turn H 3 SO 3 ). Sulphide of Arsenicum Ammonia Sulphuris lodidum Deficiency of Iodine . . Quantitative analysis . . 244 Syrupi Deficiency of Sugar . . . Specific gravity .... 466 Tamarind us . . . . Traces of Copper .... Iron 168 Veratria .... r Mineral matter .... Sulphates Incineration Chloride or Nitrate of Ba- 86 rium 276 Zinci Acetas . . . - Chlorides Nitrate of Silver . . . . 240 Metals (As, Cd, Cu, Pb) . Iron (acetate) Sulphuretted Hydrogen . 229 Nitric Acid : Ammonia . 139 L Copper (acetate) .... Ammonia 169 1 r Sulphates Chloride or Nitrate of Ba- 1 Zinci Carbonas . . -| 1 Chlorides rium to acid sol. . . . Nitr. of Silver to acid sol. 276 240 L Copper (carbonate) . . . Ammonia to acid solution 169 1 r Metals (As, Cd, Cu, Pb) . Sulphuretted Hydrogen . 229 Sulphates Chloride or Nitrate of Ba- I Zinci Chloridum . ^ 1 1 1 Calcium (chloride) . . . rium Oxalate of Ammonium . 276 98 1 1 Ferrous salts (chloride) . Ferridcyanide of Potass’m 137 1 1 Ferric salts (chloride) . . Ferrocyanide of Potass’m 137 Carbonate (of zinc) , . . Sulphates (sodium or zinc) Effervescence with acids . Chloride or Nitrate of Ba- 280 Zinci Oxidum . . rium to acid sol. . . • 276 1 1 Clilorides Nitr. of Silver to acid sol. 240 1 Copper (oxide) . . . . Ammonia to acid solution 169 f Metal (As, Cd, Cu, Pb) . Iron (sulphate) . . . . Sulphuretted hydrogen . 229 Zinci Sulphas . . -< 1 Tincture of galls .... Nitric acid: Ammonia 318 139 L Copper (sulphate) . . . Ammonia 169 r Sulphate (of zinc) . . . Chloride or Nitrate of Ba- Zinci Valerianas . ^ I rium 276 1 Butyrate (of zinc) . . . Acetate of Copper, etc. 322 APPENDIX 549 o ^ c; c o o c5 ^T-^OOOOOOrnS ^ 05 I— ^ O CSr-i'^r-josiO'-rHO C:^GOQO'^'^.rH O.S'^®^^t^'^coo60?o Oi «a 5 (rO'^ 0 'r^r-l ^ rH r-( (Tq CO C^ r— I f-l O « 4 -- ^ 'r^ ^ ooSoo CO uo CO g O ^ 05 '-' t- (M «0> a>.2 % <5i0^coO^G6co c3 g ^ ° §"1 Og«§ooo.n ^ OO'rfH-tocnnn.r; . 'o -( c3 -»-^>-r^ -.cocqcq.q 73 " X CO . 2^0 (M ^ • ''Co •+ 3 S 9 SS I X ^ ^ p lO c g L. ^ C S C P o o O O rH O 'O -S X II ^ O W ^ S , O O TO o a tH. S P G HH SO P 03 05 ".--“a 1:1 SO «i ^.o^-'I'i? s|fc 3 C3 'o? .2 cT C § T'-^ -^-H P' ' '-' O ^ Q_hh P Ph o ^ ^ HH rrt «*- o C*_ 03 ■g <5 _g g ® ® g o O £"0 o ^ ^ .^02^ 2^^'^_o^^_q & 5 S S .a S .2 g S w or-iomowoo GO ^ cIh P ® II CO g c3 O CQ lO (M o rp »o 2 52 " oT COOOco^cocO(MC a o a a. « .a 3 o o "g 2 2 -5 • CW ^ r-* tr ^ . 2 'oii '3 OOo ^ PPPt ^ P^ o .a .a * 2 . o '2 *p VT S-. H 03 H PQ be be > bo a 03 550 APPENDIX THE PROPORTION BY WEIGHT OF ABSOLUTE OR PLAIN ALCOHOL (C2H5HO) IN 100 PARTS OF REAL SPIRITS OF DIFFERENT SPECIFIC GRAVITIES (fOWNES). Sp, gr. at 60° Per- centage Sp. gr. at 60° Per- centage Sp. gf. at 60° Per- centage 05° 5 C.). of real (15° 5 C.). of real (15° 5 C ). of real 0.9991 . alcohol. ... 0.5 0.9511 . alcohol. . . . 34 0.8769 . . . alcohol. . 68 0.9981 . ... 1 0.9490 . . . . 35 0.8745 . . . . 69 0.9965 . ... 2 0.9470 . . . . 36 0.8721 . . . . 70 0.994T . . . . 3 0.9452 . . . . 37 0.8696 . . . . 71 0.9930 . ... 4 0.9434 . . . . 38 0.8672 . . . . 72 0.9914 . ... 5 0.9416 . 0.8649 . . . . 73 0.9898 . . . . 6 0.9396 . . . . 40 0.8625 . . . . 74 0.9884 . . . . 7 0.9376 . . . . 41 0.8603 . . . . 75 0.9869 . . . . 8 0.9356 . . . . 42 0.8581 . . . . 76 0.9855 . . . . 9 0.9335 . . . . 43 - 0.8557 . . . . 77 0.9841 . . . . 10 0.9314 . . . . 44 0.8533 . . . . 78 0.9828 . . . . 11 0.9292 . . . . 45 0.8508 . . . . 79 0.9815 . . . . 12 0.9270 . . . . 46 0.8483 . . . . 80 0.9802 . . . . 13 0.9249 . . . . 47 0.8459 . . . . 81 0.9Y89 . ... 14 0.9228 . . . . 48 0.8434 . . . . 82 0.9718 . . . . 15 0.9206 . . . . 49 0.8408 . . . . 83 0.9766 . . . . 16 0.9184 . . . . 50 0.8382 . . . . 84 0.9753 . . . . 17 0.9160 . . . . 51 0.8357 . . . . 85 0.9741 . . . . 18 0.9135 . . . . 52 0.8331 . . . . 86 0.9728 . . . . 19 0.9113 . . . . 53 0.8305 . . . . 87 0.9716 . . 20 0.9090 . . . . 54 0.8279 . . . . 88 0.9704 . . . . 21 0.9069 . . . . 55 0.8254 . . . . 89 0.9691". ... 22 0.9047 . . . . 56 0.8228 . . . . 90 0.9678 . . . . 23 0.9025 . . . . 57 0.8199 . . . . 91 0.9665 . . . . 24 0.9001 . 0.8172 . . . . 92 0.9652 . . . . 25 0.8979 . . . . 59 0.8145 . . . . 93 0.9638 . . . . 26 0.8956 . . . . 60 0.8118 . . . . 94 0.9623 . ...27 0.8932 . . . . 61 0.8089 . . . . 95 0.9609 . . . . 28 0.8908 . . . . 62 0.8061 . . . . 96 0.9593 . . . . 29 0.8886 . . . . 63 0-8031 . . . . 97 0.9578 . . . . 30 0.8863 . . . . 64 0.8001 . . . . 98 0.9560 . . . . 31 0.8840 . . . . 65 0.7969 . . . . 99 0.9544 . . . . 32 0.8816 . . . . 66 0.7938 . . . . 100 0.9528 . . . . 33 0.8793 . . . . 67 APPENDIX. 551 THE ELEMENTS. Aluminium (Al/^) . Antimony Arsenicum (As^^^) . Barium . . . . . Beryllium (Glucinum) Bismuth (Bi^”) Boron Bromine (79.75, stas) . Cadmium .... Caesium Calcium ..... Carbon (C”) . . . Cerium (Ce^^) .... Chlorine (35.368, stas) . Chromium (Cr/^) . Cobalt (Co”) .... Copper Didymium .... Erbium?. . . . . Fluorine ..... Glucinum. See Beryllium. Gold (AuO .... Hydrogen .... Indium .... Iodine (126 533, stas) . Iridium ..... Iron (Fe” & FeJ') . Lanthanium .... Lead (”Pb”) .... Lithium (7.004, stas) . Magnesium .... Manganese (Mn” & Mn^^) Mercury Molybdenum .... Nickel (Ni”) .... Niobium ..... Nitrogen (N^ & N”^) (14.009, stas) Osmium ..... Oxygen (15.96, stas) Palladium . . . . Phosphorus (P”^) . Symbols and atomic Atomic value. weight. . 2T.5 . Sb^ 122 . As^ 15 . Ba” 13T . Be" 9.5 . Br 210 . B'" 11 . Bi" 80 . Ccl" 112 . Cs' 183 . Ca" 40 . 12 . Ce^' 92 . OF 35.5 . Cr^' 52.5 . Co^' 58.8 . Cu" 63.5 . D" 96 . Eb" 112.6 . F' 19 . All"' 196.1 .. H' 1 t5.6 . r 127 . 10^ 197 . Fe^* 56 . L" 92 . Pb'^ 207 . LF 7 . Mg" 24 . 55 • Hg" 200 . Mo^' 96 . Npi 58.8 . Nb^ 97.6 . N'^ 14 . 199 . 0" 16 . 106.5 . P'^ 31 552 APPENDIX Platinum (197.88, Andrews) Symbols and atomic value. . Pt*’' Atomic weight. 198 Potassium (39.04, stas) . K' 39 Phodium . 104.3 Kubidium . Rb' 85.3 Piithenium . Ru'^ 104.2 Selenium . t9.5 Silicon . 28 Silver (107.66, stas) • Ag' 108 Sodium (22.98, Stas) . . Na' 23 Strontium . Sr" 8Y.5 Sulphur (S^^ & S^^) . 32 Tantalum . Ta’^ 182 Tellurium . 129 Thallium (203. Cropkes) Tliorinum or Thorium . TP” 204 . Th" 238 Tin (Sn'O . 118 Titanium Tiiv 50 Tungsten 184 Uranium. . 120 Yanadium . V'^ 51.3 Yttrium . . Y" 61.7 Zinc . Zn” 65 Zirconium . ZP^ 89.5 Total . 63 The quantivalence or atomic value of some elements is, apparentlj, variable ; in the above Table the full coefficients are given in the column of symbols, other common values in brackets. Atomic weights are sometimes obscurely termed equivalents. INDEX Abies halsamea^ 411 excelsa, 411 canadensis^ 412 Absinthin, 355 Absinthium, 355 Absinthol, 407 Absolute alcohol, 374, 449 Acacice gummi, 97 gummi, impurities in, 541 Acetate of ammonium, solution of, 78 amyl, 389 ethyl, 268 copper, 168 iron, 117 lead, 186 morphia, 340 potassium, 57 sodium, 69 zinc, 112 Acetates, 265 analytical reactions of, 265 decomposition of aqueous so- lution of, 266 volumetric estimation of, 484 Acetic acid, 265, 266, 404 ether, 268 glacial, 266, 451 volumetric estimation of fn 484 Acetone, 268 Acetonitrate of barium, 108 Acetum, 265 cantharidis, 265 colchici, 265 destillatum, 265 impurities in, 267, 541 lobelice, 265 opii, 265 sanguinarice, 265 scillcc,, 265 Acetyl, 266 47 Acid, acetic, 265, 266, 404 acetic, glacial, 266, 451 aconitic, 289 arable, 358 angelic, 406 arachidic, 404 arsenic, 146 arsenious, 144 benzoic, 298, 413, 451 boracic, 295 bromic, 263 butyric, 322, 404 cantharidic, 409 caproic, 404 caprylic, 404 carbazotic, 394 carbolic, 391, 451 carbolic, impure, 394 carbonic, 27, 278 carminic, 300 cathartic, 366 cathartogenic, 366 cerotic, 404 cetraric, 300 chloric, 259, 261 cholalic, 401 chromic, 211 chrysophanic, 300 chrysammic, 393 cinnamic, 413 citric, 289 colopholic, 410 colophonic, 410 copaivic, 411 cresylic, 392 cryptophanic, 429 cyanic, 300 dextroracemic, 285 dextrotartaric, 285 dithionic, 307 erucic, 403 eugenic, 407 554 INDEX. Acid — equisetic, 289 fluoric, 304 formic, 300, 404 gallic, 301, 318 gambogic, 412 gaultheric, 390 glacial acetic, 266, 451 guaiaretinic, 369 gnmmic, 258 liemidesmic, 301 hippuric, 301, 433, 436 hydriodic, 243 hydrobromic, 241 • hydrochloric, 26, 238 common, 238 dilute, 238 hydrocyanic, 247, 249 dilute, 249 hydroferridcyanic, 303 hydroferrocyanic, 302 hydrofluoric, 304 hydrosulpliuric, 269 hypochlorous, 260 hypopliosphorous, 304 hyposulphurous, 307 iodic, 263 jalapic, 369 lactic, 309 lauric, 404 litliic, 320 Isevoracemic, 285 laevotartaric, 285 malic, 309 mastichic, 411 meconic, 310, 424 melissic, 404 inetaboracic, 295 metagummic, 258 metantimonic, 157 nietapliospboric, 310 inetastannic, 215 mimotannic, 318 mucic, 365 muriatic, 238 myristic, 402 myrrliic, 412 naphthalic, 298 nitric, 252, 254 dilute, 255 nitrobydrocbloric, 162, 255 dilute, 162, 255 nitromuriatic, 255 nitrous, 311 Acid — oenanthylic, 404 oleic, 400 orthophosphoric, 312 oxalic, 282 palmitic, 404 paratartaric, 285 pelargonic, 404 pentathionic, 307 perchloric, 262 plienic, 391 phospliomolybdic, 426, 427 phosphoric, 22, 293, 312 dilute, 293 glacial, 294 phosphorous, 312 phthalic, 299 picric, 394 pimaric, 410 pinic, 410 polygallic, 371 propionic, 404 prussic, 247 pyrogallic, 319 pyroligneous, 365 pyrophosphoric, 311, 312, 313 racemic, 285 rlieic, 300 rhubarbaric, 300 rutic, 404 saccharic, 365 salicylous, 390 sarcolactic, 309 silicic, 314 stannic, 215 stearic, 400, 404 < succinic, 315, 407 sulphetbylic, 374 sulpliindigotic, 258 sulphindylic, 258 sulpliocarbolic, 392 sulphocyanic, 316 sulphoplienic, 392 sulpbovinic, 374 sulphuric, 275 sulphuric, aromatic, 276 dilute, 276 sulphurous, 272 sulphydric, 269 sylvic, 410 tannic, 316 tartaric, 284, 315 tetrathionic, 307 tiglic, 402 INDEX. 555 Acid — trinitrocarbolic, 392 tritliionic, 307 uric, 320 valerianic, 320, 404 Acid carbonate of potassium, 58, 408 carbonate of sodium, 69 salts, 61, 269 solution of arsenic, 145 tartrate of potassium, 52, 65 tartrate of sodium, 66 Acidimetry, 265 Acids, analytical detection of, 336 antidotes to, 237 definition of, 235 of chlorine, 262 quanti tati ve estimation of, 443 volumetric, estimation of offi- cial, 445 Acidulous radicals, formulae and quantivalence of, 55, 104, 236, 237 radicals, qualitative detec- tion of, 323 radicals, quantitative estima- tion of salts of, 514 radicals, tables to aid in the detection of, 325, 326 Acidum^ aceticum, 266 aceticum^ impurities in, 541 aceticum dilutum, 266 aceticum glaciate^ 266 aceticum glaciale, impurities in, 541 arseniosum, 144 henzoicum, 298 horacicum, impurities in, 541 ' caj'holicum, 392 carbolicum impurum, 392 chrornicum^ 211 citricum, 289 citricuin, impurities in, 541 gallicum, 318 gallicum, impurities in, 541 hgdrochloricum, 26, 239 hydrochloricunij impurities in, 541 hydro chloricum dilutum, 239 hydrocyanicum dilutum, 239 hydrocyanicum dilutum, im- purities in, 541 lacticum, 309 nitricum, 255 Acidum — nitricum, impurities in, 541 nitricum dilutum, 255 nitro-h ydrochloricum dilutum, 255 nitro-muriaticum, 255 oxalicum, 282 oxalicum, impurities in, 541 phosphoricum dilutum, 293 ptiosphoricum dilutum, impuri- ties in, 541 sulphuricum, 276 sulphuricum, impurities in, 542 sulphuricuin aromnticum, 276 sulphuricum dilutum, 276 sulphur osum, 273 sulphurosum, impurities in 542 tannicum, 317 tannicum, impurities in, 542 iartaricum, 285 tartaricum, impurities in, 542 valerianicum, 322 Aconiti folia, 349 radix, 349 Aconitia, 349 impurities in, 542 Aconitic acid, 289 Aconitina, 349 Aconitine, 349 Aconitum napellus, 349 Acrolein, 394 Adeps benzoatus, 401 prceparatus, 401 prceparatus, impurities in, 542 u^gle marmelos, 318 Aerated brq.ad, 362 water, 71 jEther, 376 fortior, 378 impurities in, 542 purus, 378 purus, impurities in, 542 Affinity, chemical, 34 Agate, 314 Air, composition, 24 infiueiice of animals and plants on, 18 nitrogen in the, 23 oxygen in the, 15 relative weight of the, 24 weight of 1 cubic cent., 470 weight of 100 cub. inch, 470 Alabaster, 90 556 INDEX. Albumen, 395 detection of in urine, 429 vegetable, 398 Albumen ovi, 395 Albumenoid substances, 395 Alchemy, 13 Alcohol^ 372 absolute, 374, 449 amylic, 389, 449 and allied bodies, 372 et seq. benzylic, 413 butylic, 322 cinnamic, 413 dilutum, 373 ethylic, 373 fortius, 373 from sugar, 362 gl^^ceric, 394 in 100 parts of spirits of dif- ferent densities,Table show- ing the proportion of, 550 methylic, 383 phenic, 391 quantitative estimation of, 536 radicals, 382 real, 374 test for impurities in, 542 test for purity of, 375, 487 Alcohol amylicum, 389 amylicum, impurities in, 542 Alcoholates of chloral, 389 Alcohols, 381 Alcohometer, 466 Aldehyd, 375 benzoic, 299 euodic, 408 lauric, 408 rutic, 408 Aldehyds, 382 Ale, 357 Alexandrian senna, 366 Algarotli’s powder, 156 Alizarin, 415 Alkalies, analytical separation of the, 85 antidotes to, 237 quantitative estimation of the, 478 Alkalimetry, 482 Alkaline carbonates, volumetric estimation of the, 478 earths, 108 solution of arsenic, 144 1 Alkaloids, 338 antidotes to the, 340 distinguished, 339 nomenclature of, 339 poisonous, examination . for, 423 et seq. Alkanet, 415 Alkanna tinctoria, 415 Allium, 393 Allotropic bodies, 258 Allotropy, 258 _ Alloxan, 320 Alloy, 172 Alloys, analysis of, 334 Allyl, 393 sulphide of, 393 sulphocyanate of, 394 Almond-oil, 402, 403 Almonds, oil of bitter, 366, 391 oil of bitter, test fornitroben- zol in, 299 Aloe harbadensis, 393 socotrina, 393 Aloins, 393 Althcea, 310 Alum cake, 116 Alum, 116 chrome-, 116 dried, 117 1 -flour, 116 iron-, 117 potash-, 116 roche or rock, 117 soda-, 116 Alumen, 116 impurities in, 542 exsiccatum, 117 I Alumina, 117 j Aluminium, 115, 506 ! analytical reactions of, 117 and ammonium, sulphate of, 106 and sodium, double chloride of, 116 bronze, 116 derivation of word, 29 detection of in presence of iron and zinc, 139 hydrate of, 117 oxide of, 117 quantitative estimation of, 501 separation of from chromium and iron, 213 INDEX. 55t Aluminium — silicate of, 116 sulphate of, 116 Amalgam, 172 ammonium, 76 Amber, 315 oil of, 315 American senna, 367 turpentine, 408 Amianth, 314 Amido-chloride of mercury, 181 Amines, 339 Ammonia, 76 fetid spirit of, 79 gas, composition of, 77 preparation of, 77 solution of, 77 volcanic, 76 volumetric estimation of solu- tions of, 478 Ammoniacal liquor, 76 salts, sources of, 76 Ammoniacum, 412 Ammoniated mercury, 181 varieties of, 181 Ammonice (vide Ammonii) Ammonii acetatis liquor ^ 78 aromaticus, spiritiis, 79 benzoas, 79, 299 henzoas, impurities in, 498 bromidum, 80 carbonas^ 78 carbonaSj impurities in, 542 chloridunif 76 chloridum, impurities in, 542 citratis, liquor^ 79 foetidus, spiritus, 79 fortior, liquor^ 77 iodidum, 80 liquor, 77 nitras, 257 nitras, impurities in, 542 phosphas, 79 sulphas, 76 Ammonio-cliloride of mercury, 181 -citrate of iron, 130 -ferric sulphate, 117 -magnesian phosphate, 103, 294 -nitrate of silver, 153, 182 -sulphate of copper, 153, 182 -sulphate of magnesium, 481 -tartrate of iron, 130 Ammonium, 75 acetate of, 78 -amalgam, 76 analytical reactions of, 82 and magnesium, phosphate of, 103 and magnesium, arseniate of, 103 and platinum, double chloride of, 88, 220 arseniate, 146 bicarbonate, 78 benzoate of, 79, 299 bromide of, 80 carbamate, 78 carbonate of, 78 carbonate, solution of, 79 chloride of, 76 citrate of, 79 cyan ate of, 301 derivation of word, 28 derivatives, 182 hydrate of, 77 nitrate, 257 oxalate of, 80 phosphate of, 79 potassium, and sodium, sepa- ration of, 85 quantitative estimation of, 502 salts, source of, 75 salts, volatility of, 84 sulphate, 76 sulphide of, 81 sulphydrate of, 80 tartrate of, 84 volumetric estimation of car- bonate of, 478 Amorphous, meaning of, 160 phosphorus, 293 Amygdala amara, 365, 403 dulcis, 365, 403 Amygdalin, 365 Amyl, 381 acetate of, 389 valerianate of, 389 Amylaceous substances, 355 Amylamine, 339 Amylic alcohol, 289, 449 Amylum, 355 impurities in, 542 Analogies between chlorine, bro- mine, and iodine, 244 of sodium and potassium salts, 73 47 * 558 INDEX. Analogy (/f salts, 73 Analysis, 84 aided by sifting, 330 blowpipe, 331 gas-, 319, 336 gravimetric, 446, 497 meaning of word, 53 organic, 525 practical, 84 proximate, 525 qualitative, 84 quantitative, 445 spectrum-, 336 and synthesis, 53 systematic, for the detection and separation of the me- tals, 85, 106, 139, 162, 165, 195, 333 ultimate, 525 volumetric, 446, 475 of gases and vapors, 336 of insoluble salts, 334 et seq. of medicines, 336 of salts, 323 of substances having un- known properties, 335 Analytical chemists, 14, note. detection of the acidulous radicals of salts soluble in water. 323 memoranda, 230, 237 Analytical reactions of acetates, 267 albumen, 395 alcohol, 374 aldehyd, 376 aluminium, 117 ammonium, 82 ainygdalin, 366 antimony, 159, 419 arsenicum, 148, 419 atropia, 350 barium, 88 beberia, 350 benzoates, 300 berberia, 351 bile, 401 bismuth, 225 borates, 297 bromides, 242 brucine, 348 cadmium, 222 cafl'eia,353 calcium, 97 Analytical reactions of — carbonates, 280 chloral hydrate, 387 chlorates, 262 chlorides, 240, 421 chromates, 211 chromium, 212 citrates, 291 cobalt, 207 conia, 352 copper, 168, 419 cyanides, 250 ferric salts, 137 ferridcyanides, 304 ferrocyanides, 303 ferrous salts, 136 fluorides, 304 formates, 301 gallic acid, 319 glucosides, 365 i^lvcerine, 394 gold, 218 guaiacin, 369 hippurates, 302 hydrocyanic acid, 250, 421 hypochlorites, 260 hypophosphites, 306 hyposulphites, 308 iodides, 245 iron, 136 lactates, 309 lead, 189, 419 lithates, 320 lithium, 201 magnesium, 102 malates, 309 manganese, 204 meconates, 310, 424 mercuric salts, 180,410 mercurous salts, 180, 183 metaphosphates, 310 morphia, 341, 424 nickel, 209 nicotia, 352 nitrates, 256 nitrites, 311 nitrous ether, 379 oxalates, 282, 421 phosphates, 294 phosphites, 313 * platinum, 219 potassium, 64 pyrogallic acid, 319 pyrophosphates. 313 INDEX. 559 Analytical reactions of — qiiinia, 344 salicin, 320 silicates, 315 silver, 193 sodium, 74 starch, 356 strontium, 202 strychnia, 347, 423 succinates, 316 sugar, 361 sulphates, 277 sulphides, 271 sulphites, 273 sulphocyanates, 316 sulphuric acid, 411 tannic acid, 317 tartrates, 287 theia, 353 tin, 215, 216 urates, 320 veratria, 254 zinc, 114 Anchusa tinctoria^ 415 Anchusin, 415 Aneroid barometer, 447 Anethene, 406 Angelic acid, 406 Angelic powder, 156 Angustura, 355 Angusturin, 355 Anhydride, acetic, 266 antimonic, 156 antimonious, 156 boracic, 297 carbonic, 278 chlorochromic, 212 chromic, 211 nitric, 252, 255 nitrous, 257 phosphoric, 22, 310 silicic, 315 sulphuric, 276 sulphurous, 272 Anhydrides, 70 Anhydrous bodies, 70 nitric acid, 255 perchloride of iron, 125 sulphate of copper, 168 Aniline, 392, 417 colors, 417 Animal charcoal, 95 decolorizing power of, 95 Animal — rouge, 416 Animals and plants, complement- ary action of air, 18 Anise, 406 Anise-fruit, 406 Aniseed-oil, 406 Annatto, 415 Anthemidis Jiores, 355, 406 Anthemis nohilis^ 406 Anthracen, 393 Anthracite, 213 Antichlor, 273 Antidotes to acids, 237 alkalies, 237 alkaloids, 340 antimony, 161 arsenic, 153 barium, 88 carbolic acid, 392 copper, 170 cyanides, 250 hydrochloric acid, 241 hydrocyanic acid, 251 lead, 190 mercury, 184 nitric acid, 259 oxalic acid, 283 silver, 195 sulphuric acid, 278 tin, 216 zinc, 115 Antimonial wine, 157 Antimoniate of sodium, 74 potassium, 74 Antimonic anhydride, 157 chloride, 156 oxide, 157 Antimonii chloridi, liquor^ 155, 509 oxidum, 156 oxidiirn, impurities in, 542 et potassoe tartras, 157 oxysulphuretum, 158 sulphur etum^ 158 Antimonious anhydride, 156 chloride, 155 oxide, 156 oxychloride, 156 Antimonium nigrum^ 155 nigrum, impurities in, 542 sulphur a turn., 157 tartaratum, 157, 284 tartaratum, quantitative esti- mation of antimony in, 509 560 INDEX Antimoniuretted hydrogen, 160 Antimony, 143, 155, 284, 451, 509 analytical reactions of, 159 and arsenic, analytical sepa- ration of, 162 from arsenic, to distinguish, 151 and potassium, tartrate of, 157, 284 antidote to, 161 black, 1 55 butter of, 155 chloride of, 155 crude, 155 derivation of word, 29 hydride of, 160 in organic mixtures, detection of, 419 oxide of, 156 oxychloride of, 156 oxysulphide of, 157 pentachloride of, 157 potassio-tartrate of, 157 quantitative estimation of, 509 solution of chloride of, 155, 509 sulphide of, 155, 159 sulphur salts of, 158 sulphurated, 157 tartarated, 157 Antiseptic, 302 AutoZone, 211, 245, 437 Apatite, 295 Apomorphia, 342 Aporetine, 300 Apparatus, ix. for experiments, ix. for volumetric analysis, 475 list of, ix. Apple, essence of, 390 oil, o90 Aqua, 108 Aqua acidi carholici, 391 acidi carhonici, 278 ammonice, 77 ammonicB fortior, 77 amygdalce amaroe, 366 aneihi, 405 • aurantii Jioris, 405, 406 aurautri Jloris, impurities in, 542 camphorce, 400 clilorinii, 25, 240 creasoti, 392 Aqua — desiillata, 109 destillata, impurities in, 542 fortis, 255 laurocerasi, 366 menthi^ piperitca, 405 viridis, 405 regia, 162, 255 roscB, 405, 407 Arabin, 97 Arachidic acid, 404 Arhor Dianoe, 194 Arbutin, 318, 366 Arctostaphglos uva ursi, 366 Archil, 416 Are, 456 Argal, 284 Argent-ammon-ammonium, ni- trate of, 182 Argenti cyanidum, 194 nitras, 193 nitras, impurities in, 542 oxldum, 193 oxidum, impurities in, 542 Argentic chloride, sulphide, etc., vide salts of silver. Argentiferous galena, 191 Argentum, 20, 192 r Argentum purijicatum, 102 purijicatum, impurities in, 542 Argol, 284 Armenian bole, 415 Armoracioe radix, 406 Arnatto, 415 Arnica, 411 Arnicse radix, 411 Arnicin, 411 Arnotto, 450 Arrowroot, 357 Arseniates, 146 Arseniate of ammonium, 146 barium, 89, 153 calcium, 153 copper, 153 iron, 147, 492 magnesium and ammonium, 103 silver, 153 sodium, 146 volumetric estimation of, 489 zinc, 153 Arsenic acid, 146 INDEX. 561 Arsenic — and arsenical solutions, volu- metric estimation of official, 489 anhydride, 146 odor of, 146 in carbonate of potassium, solution of, 144 in hydrochloric acid, solution of, 145 white, 144 Arsenical ores, 144 sulphur, 152 Arsenici iodidum^ 143 Arsenicum, 143 analytical reactions of, 148 antidotes to, 153 and antimony, analytical se- paration of, 162 bromide, 143 chloride, 143 derivation of word, 29 detection of in metallic cop- per, 149 detection of, in organic mix- tures, 419 Fleitmann’s test for, 150 from antimony, to distin- guish, 151 hydride of, 149 iodide of, 143 Marsh’s test for, 149 red native sulphide of, 144 quantitative estimation of, 489, 508 Reinsch’s test for, 148 sources of, 144 sulphide of, 144, 151 yellow native sulphide of, 144 Arsenide of cobalt, 207 Arsenio-sulphide of iron, 144 of nickel, 208 Arsenious acid, 144 anhydride, 144 Arsenites, 144 Arsenite of copper, 153 potassium, 144 silver, 153 sodium, 144 Arsenuretted hydrogen, 149 Artemisia, 370 Art of chemistry, 13 Artificial alkaloids, 339 gastric juice, 399 Asbestos, 314 Ash, 86 black-, 73 bone-, 94 soda-, 73 Ashes, analysis of (mixed solids), 331 Asparegin, 310 Assafoetida, 412 -ate, meaning of, 60 Atmosphere, carbonic acid in, 279 composition of, 24 nitrogen in, 23 oxygen in, 15, 24 Atmospheric pressure, measure- ment of, 446 Atom, definition of, 50 weights, definition of, 45 Atomic proportions, 173, 176 theory, 43 weights, 43 Atomicity, 45 Atoms, 43, 44 quantivalence of, 47 definition of, 48 Atropa belladonna, 350 Atropia, 350 impurities in, 542 Atropice, sulphas, 350 sulphas, impurities in, 542 Atropine, 350 Attar of rose, 407 Aurantii cortex, 355, 406 amari cortex, 406 dulcis cortex, 406 flores, 406 Auric chloride, 217 sulphide, 217 Aurum, 31 Avence farina, 356 Avignon grains, 414 Avogadro’s and Ampere’s law, 44, 46 Bael fruit, 318 Baking-powder, 362 Balance, 453 Balloons, coal-gas for, 21 hydrogen for, 21 Balm-of-Gilead fir, 412 Balsam, Canada, 412 copaiva, 411 fir, 408 Peru, 413 562 INDEX Balsam — Storax, 413 Tolu, 413 Bahamodendron myrrha, 412 Balsamum Peruvianum, 413 Peruvianum, impurities in, 642 Tolutanwnij 413 Balsams, 413 Barbaloin, 393 Baric chloride, nitrate, etc., vide salts of barium. Barii carhonas, 87 Barium, 87 acetonitrate of, 108 analytical reactions of, 88 and calcium, separation of, from magnesium, 106 antidotes to, 88 arseniate of, 89 carbonate, 89 native, 87 cnrbonate of, 87 chloride of, 87 chromate of, 88 derivation of word, 28 detection of, in presence of calcium and magnesium, 85, 106 hydrate of, 88 nitrate of, 87 peroxide of, 88 phosphate of, 89, 295 oxalate of, 89, 282 quantitative estimation, 502 salts, antidote to, 88 silico-fluoride of, 89 sulphate of, 88 sulphide of, 88 sulphite, 274 Barley-sugar, 364 Baronieter, 446 Baryta, 88 -water, 88 Basalt, 116 Base, meaning of, 237 organic, 338 Bassorin, 97, 358 Bastard satfron, 415 Bauxite, 116 Basylous radicals, 104 Bay rum, 372 Bay-salt, 67 Bearberry, 318 Beaver, 411 Beherice sulphas, 350 sulphas, impurities in, 542 Beberia or beberine, 350 Beer, 257 Beetroot, 361 Belm fructus, 318 Belladonnce folia j 350 radix, 350 Bell-metal, 213 Bend glass tubes, to, 16 Benzine-collis, 391 Benzoate of ammonium, 79, 299 Benzoated lard, 401 Benzoates, 298 Benzoic acid, 298, 449, 451 aldehyde, 299 glycocine, 302 Benzoin, 298, 413 Benzoinum, 298, 413 Benzol, 391, 449 Benzoyl, hydrate of, 299 hydride of, 366, 413 Benzyl, benzoate of, 413 cinnamate of, 413 Benzylic alcohol, 413 Berberia or berberine, 351 Bergamot oil, 406 Berlin blue, 416 red, 415 Berryllium, 507 Bi-, the prefix, 59 Bibasic, vide Dibasic. Bibulous paper, 93 Bicarbonate of ammonium, 78 of potassium, 58, 286, 290, 478 of sodium, 69, 286, 290, 478 Bichromate of potassium, 210 Bile, 401 detection of, in urine, 430 test for presence of, 401 Biliary calculi, 441 Bismuth, 222. 451, 467, 510 and ammonium, solution of citrate of, 225 analytical reactions of, 225 carbonate of,^24 citrate of, 225 derivation of word, 31 -lozenge, 224 nitrate of, 223 quantitative estimation of, 510 -salts, composition of, 225 INDEX 563 Bismuth— subcarconate or oxycarbon- ate, 224 subnitrate or oxynitrate of, 223 subnitrate of, 223 sulphate of, 225 sulphide of, 226 Bismuthi carbonas, 224 carbonas, estimation of bis- muth in, 510 carbonas^ impurities in, 542 subcarbonas^ 224 subnilras, 223 Bismuthum^ 223 purijicatum^ 223 purijicaturriy impurities in, 543 Bisulphide of carbon, 382 Bitter almonds, oil of, 366, 391 cassava, 356 principles, 355 sweet, 353 Bituminous coal, 213 Bivalence, 47 Bivalent radicals, 47, 105, 108 Bixa 07'ellanaj 415 Bixin, 415 Black antimony, 155 -ash, 73 -band, 119 bone-, 94 coloring-matters, 414 dyes, 417 flux, 145 hydrate of iron, 133 ink, 318 -lead, 26 oxide of copper, 169 oxide of iron, 134 oxide of manganese, 203 oxide of mercury, 179 pepper, 353 Black oak, 415 Bladder-green, 416 Blanc de Perle, 224 Bleaching by chlorine, 25 -liquor, 97 -powder, 96 Blende, 109 Block tin, 213 Blood, 396,437 detection of in organic matter, 437 Blood — hydrocyanic acid in the, 251 Blood-root, 353 Bloodroot vinegar, 265 Blood-stains, 437 Blowpipe-analysis, 331 -flame, 331 Blue coloring-matters, 416 copperas, 121 indigo, 258 ointment, 171 pill, 171 Prussian, 137, 303 stone, 168 Turnbull’s, 304 vitriol, 121, 168 Boiling-points of various sub- stances, 449, 450 “Bonds” (Frankland), 114 Bone-ash, 94 -black, 94 -earth, 292 Bones, composition of, 292 Boracic acid, 296 anhydride, 296 Borates, 296 analytical reactions of, 297 Borax, 297 volumetric estimation of, 480 Borax bead, 205 Bordeaux turpentine, 408 Borneeiie, 409 Borneo camphor, 409 Boron, 297 chloride of, 297 derivation of word, 30 flame, 298 fluoride of, 297 Borotartrate of potassium, 297 Bos taunts, 401 Bourdon barometer, 447 Brandy, 376 Brass, 109 Brazil wood, 415 Bread, 356, 362 aerated, 362 making, 362 Brezilin, 415 Bright’s disease, 430 Britannia metal, 155, 185, 214 British gum, 357 Bromal, 389 alcoholates of, 389 564 INDEX. Bromal — * hydrate of, 389 Bromate of potassiuiii, 63 Bromates, 263 Bromic acid, 63, 263 Bromide of ammonium, 242 arsenicum, 143 iron, 124 potassium, 63, 241 potassium, volumetrical esti- mation of, 487 of silver, 194 of sulphur, 272 Bromides, 241 analytical reactions of, 242 quantitative analysis of, 487, 515 separation of, from chlorides and iodides, 246 Bromine, 241 analytical separation of, 242 derivation of word, 39 its analogy to chlorine and iodine, 243 solution of, 242 volumetric estimation of free, 515 Brominium, 241 Bromum, 241 impurities in, 543 Bronze, 214 aluminium, 116 coinage, 167 Bronzing-powder, 216 Broom-tops, 353 Brown coloring-matters, 417 haematite, 119 rosin, 410 sugar, 361 Brucia, 248 Brucine, 248 Brunswick green, 152 Buchu folia, 355 Buchu, oil of, 406 Bucktliorn-green, 416 -juice, 367 Bunsen gas-burners, 21 Burette, Mohr’s, 476 Burgundy pitch, 411 Burners, gas-, 17, 21 Burnett’s disinfecting fluid. 111 Burnt sugar, 361 ochre, 415 umber, 417 Butter, 398 of antimony, 155 of orris, 407 Butyl, 322 sulphocyanate, 382 Butylic alcohol, 322 Butyrates, 322 I Butyric acid, 322, 404 By-products, 176 Cacao oil, 402 Cadmii iodidum, 221 ' iodidum, impurities in, 543 I Cadmium, 221 analytical reactions of, 222 carbonate, 222 derivation of word, 31 hydrate of, 222 iodide of, 221 nitrate, 222 sulphate, 222 sulphide of, 222 Ccesalpinia hraziliensis, 415 Caesium, 551 Caffeia, 353 Cajuput oil, 406 Caking coal, 213 Calabar bean, 353 Calamine, 109 Calcic, sulphate, phosphate, etc., vide salts of calcium. Calcii carbonas prcecipitata, 92 carhonas prcecipitata, impuri- ties in, 543 chloratce, liquor, 97 chloridnm, 90 chloridum, impurities in, 543 hydras, 92 phosphas, 94 phosphas, impurities in, 543 saccharatus, liquor, 92 Calcined magnesia, 102 Calcium, 90 analytical reactions of, 97 and barium, separation from magnesium, 106 carbonate of, 92 prepared, 94 chloride of, 90 chromate of, 98 citrate of, 291 derivation of word, 29 -flame, 98 fluoride of, 90 INDEX. 665 Calcium — fluoride of, in bones, 95 gummate of, 97 hydrate of, 91 hypochlorite of, 96 hypophosphite of, 305 hyposulphite of, 270 in presence of barium and magnesium, detection of, 106 oxalate of, 98, 282 oxide of, 91 phosphate of, 90, 94 polysulphide of, 270 quantitative estimation of, 504 silicate of, 90, 314 . sulphate of, 90, 97, 271 sulphite of, 274 superphosphate of, 292 tartrate of, 287 Calc-spar, 90 Calculi, urinary, 439 urinary, examination of, 439 Calomel, 171, 176 test for corrosive sublimate in, 178 tests for constituents of, 178 Calumhcc radix, 351 Calx, 91 impurities in, 543 chlorinata, 96 chlorata, 96 chloraia, impurities in, 543 Cambogia, 412 impurities in, 543 Camphor-laurel, 409 mixture, 409 oil, 409 water, 409 Camphora, 409 impurities in, 543 officinarum, 409 ^ Camphors, 409 Camwood, 415 Canada balsam, 412 Canadian turpentine, 408 Canarium commune, 412 Candle-flame, composition of, 21 Canellce albce cortex, 355 Cane-sugar, 361 Canna, 357 Cannabin, 411 Cannabis indica, 41 Cantharides, 409 48 Cantharidic acid, 409 * Cantharidin, 409 Cantharis, 409 Caoutchouc, 413 Capacity unit, 455 Capillary, 448 Caproate of glyceryl, 402 Caproic acid, 402, 404 Caproyl, 381 Caprylate of glyceryl, 402 Caprylic acid, 402, 404 Capsid fructus, 351 Capsicia, 351 Capsicine, 351 Capsicum, 351 fruit, resin of, 349 oil of, 351 Caramel, 364 Caraway oil, 407 Carbamate of ammonium, 78 Carbazotic acid, 392 Carbolic acid, 391, 449, 451 acid, antidote to, 392 Carbon, 26 bisulphite of, 382 combustion of, 26 derivation of word, 28 quantitative estimation of, in organic compounds, 525 et seq. Carbo animalis, 95 animalis purificatus, 95 animalis pur ifitatus, impurities in, 543 ligni, 95 ligni, impurities in, 499 Carbonate of ammonium, 78 ammonium, solution of, 78 barium, 89 bismuth, 225 cadmium, 222 calcium, 90, 92 prepared, 94 iron, 122, 492 iron, saccharated, 123, 492 lead, 185 lithium, 201 magnesium, 100 potassium, 52, 478 potassium acid, 58, 478 sodium, 68, 73, 279, 478 sodium, acid, 69, 478 sodium, manufacture of, 86, 279 566 INDEX. Carbonate — strontium, 202 zinc, 109, 112 Carbonates, 278 acidulous radical in, 278 analytical reactions of, 280 gravimetric estimation of, 519 volumetric estimation of alka- line, 478 Carbonic acid, 27, 279 anhydride, 279 generation of, 59 Carbonic acid gas, solubility of, in water, 71 oxide, 283, 303 Carbonization, 86 Cardamom oil, 406 Cardamomum^ 406 Carmine, 300 Carminic acid, 300 Carnallite, 54 Carrageen moss, 358 Carrotin, 415 Carthamin, 416 Carthamus tinctorius, 415 Carvene, 407 Carum, 407 Carvol, 407 Caryophyllin, 407 Cascarilla oil, 407 Cascarilla cortex, 407 Casein, 397 vegetable, 398 Cassia marilandica, 367 Cassia oil, 407 Cassice pulpa, 361 Castilloa elastica, 413 Cast-iron, 119, 451 Castor, 411 Castor fiber, 411 Castor oil, 403 Castoreum, 411 Castorin, 411 Catechu, 318 Catechu pallidum, 318 pallidum, impurities in, 543 Cathartic acid, 366 Cathartogenic acid, 367 Caustic, 193 lime, 91 lunar, 191 potash, 53 soda, 68 Cayenne pepper, 351 Cedra oil, 406 Celestine, 202 Cellulin, 359 Cellulose, 359 Celsiuses thermometer, 448 Cements, 314 Centiare, 455 Centigrade thermometer, 448 Cephalis ipecacuanha, 352 Cerasin, 358 Ceratum plumhi suhacetatis, vide Unguentum, zinci carbonatis, 112 Cera alba, 402 alba, impurities in, 543 fiava , 402 fiava', impurities in, 543 Cerebrin, 396 Cerite, 203 Cervisice fermentum, 372 Cerii oxalas, 203 oxalas, impurities in, 543 Cerium, 203 derivation of word, 30 oxalate of, 203 Ceroleine, 402 Cerotic acid, 402 Cetaceum, 402 impurities in, 543 Cetene, 402 Cetraria, 300 Cetraric acid, 300 Cetyl, hydrate of, 402 palmitate of, 402 Cevadilla, 354 Chalcedony, 314 Chalk, 94 precipitated, 92 prepared, 94 -stones, 441 Chalybeate water, 119 Chameleon, mineral, 205 Chamomile oil, 406 Char, 86 Charcoal, 26 animal, 94 animal, decolorizing power of, 94 wood, 95 Cheese, 397 Chemical action, definition of, 34 Chemical action by symbols, illus- tration of, 37, 40 affinity, 34 INDEX. 5G7 Chemical — combination, 34 combination by weight, laws of, 40 et seq. combination by volume, laws of, 44 et seq. combination different from mechanical, 33, 35 combination, laws of, 40, 171, 257, 445, 497 compound, definition of, 48 compound, 27 diagram, 49, 54 equation, 49, 54 force, 36 force, conditions for the mani- festation of, 36 formula, definition of, 49 formulae, 37, 38, 39 notation, 37, 38, 39 preparations of the Pharma- copoeias, 444 philosophy, principles of, 33 et seq. symbol, definition of, 49 symbols, 37, 38, 39 toxicology, 418 Chemist and Druggist, 14 Chemicals, 14 list of, xi. Chemism, 34 Chemistry, art of, 13 and physics, differences be- tween, 43 definition of, 48 derivation of the word, 13 inorganic, 338 object of, 14, 43 organic, 338 science of, 13 Chemists, analytical, 14 manufacturing, 14 pharmaceutical, 14 Chenopodlum^ 408 Cherry-laurel water, 366 Cherry-tree gum, 358 Chestnut-brown, 417 Chian turpentine, 408 Chili saltpetre, 252 Chimaphila, 355, 366 Chimaphila umbellatciy 366 Chinese red, 415 yellow, 414 Chirata^ 355, 366 Chiratin, 367 Chloral^ 386 Chloral hydrate, 386 alcoholates of, 389 Chlorate of potassium, 261 potassium, preparation of oxy- gen from, 16 Chlorates, 261 analytical reactions of, 262 Chloric acid, 260 Chloride of ammonium, 76 antimony, 155 arsenicum, 143 barium, 87 boron, 297 calcium, 90 calcium, removal of iron from, 90 chromium, 210 gold, 218 iron, 125 lead, 189 lime, 96 magnesium, 99 manganese, 204 mercuric ammonium, 182 mercurous ammonium, 182 mercury, 176 platinum, 219 platinum and ammonium, 83, 503 platinum and lithium, 201 platinum and potassium, 65 silicon, 315 silver, 192 sulphur, 272 tin, 214 solution of, 214 zinc. 111 Chlorides, 238 separation of, from bromides and iodides, 246 tests for, 240 estimation of, 514 Chlorinated lime, 96 volumetric estimation of, 495 soda, solution of, 72 volumetric estimation of, 495 Chlorine, 24, 239, 514 acids, 262 as a disinfectant, 25 bleaching by, 25 collection of, 24 568 INDEX Chlorine — derivation of word, 28 its analogy to bromine and iodine, 243, 246 preparation of, 24 properties of, 24 relative weight of, 25 solubility in water, 25 the active agent in bleaching- powder, 96 volumetric estimation of, 495 water, 24, 240 Chlorochromic anhydride, 212 Chloroform, 385, 450 impurities in, 543 Chlorophyll, 416, 443 Chocolate, 402 Cholalic acid, 401 Cholate of sodium, 401 Cholesterin, 396, 441 Chondrin, 398 ChonUrus crispus, 358 Chromate of barium, 88 calcium, 98 lead, 189 mercury, 212 potassium and ammonium, 89 potassium, standard solution of red, 491 silver, 187 Chromates, 211 analytical reactions of, 211 of potassium, 88, 106, 210 Chrome-alum, 117 -ironstone, 210 -red, 189 -yellow, 189 Chromic acid, 211 anhydride, 211 hydrate, 212 salts, 210 Chromium, 210 analytical reactions of, 212 chloride of, 211 derivation of word, 30 separation of, from aluminium and iron, 213 sulphate of, 211 Chromous salts, 210 Chromule, 416 Chrysophanic acid, 300 Chrysammic acid, 393 Chrysorhamnin, 415 Cicutine, 351 CincJioim Jlavce cortex^ 343 pallidce cortex^ 343 rubrce cortex^ 343 Cinchonia, 346 CinchonicB sulphas^ 346 Cinclionicia, 346 Cinchonicine, 346 Cinchonidia, 346 Cinchonidine, 346 £!inchonine, 346 Cinnabar, 170 Cinnamein, 413 Cinnamic acid, 413 alcohol, 413 Cinnamomi cortex, 407 Cinnamon oil, 407 Cinnamyl, hydride of, 413 Cissampelia, 351 Cissampeline, 351 Cissarnpelos pareira, 351 Citrate of ammonium, 79 calcium, 291 iron, 130 iron and strychnia, 130 iron and quinine, 131, 344, 582 lithium, 200 magnesium, 289 nicotia, 352 potassium, 60 volumetric estimation of, 481 quinine, 344 silver, 291 Citrates, 60, 289 analytical reactions of, 290 volumetric estimation of, 478, 481 Citric acid, 289 action of heat on, 291 saturating power of, 290, 549 Citronella oil, 407 Citronellol, 407 Citro-tartarate of sodium, 73 Classification of elements, 86, 105, 107, 230 Claviceps purpurea, 411 Clay, 116, 214 ironstone, 119 Cloves, oil of, 407 Club-moss, 403 Coal, 213 products of, 382 -gas, 382 INDEX 569 Coal-gas — for balloons, 21 -tar colors, 417 Cobalt, 207 analytical reactions of, 207 arsenide of, 207 blue, 416 derivation of word, 30 -glance, 207 hydrate of, 207 separation of, from nickel 209 sulphate of, 207 sulphide of, 207 Cobaltic ultramarine, 416 Cobalticyanide of potasium, 208 of nickel, 209 Cobalticyanides, 208 Coccus^ 300 Ilicis, 158 Cochineal, 300 Cocoa, 402 Cocoa-butter, 402 Cocoa nibs, 402 Cocoa-nut, 402 Cocoa-nut oil, 402 Cocos nucifera, 402 Codamine, 341 Codeia, 342 Cod-liver oil, 402 Coinage, copper, 167, 467 gold, 217, 467 silver, 191, 467 Coke, 26 Colchici cormuSf 354 semina, 354 Colchicia, 354 Colchicine, 354 Colchicum vinegar, 265 Colcothar, 415 Collection of gases, 16, 17 Collin, 537 Collodion, 360 Collodium, 360 flexile, 360 Colloid bodies, 537 Colocynthidis pulpa, 367 Colocynthin, 367 Colopholic acid, 410 Colophonic acid, 410 hydrate, 410 Colophonine, 411 Colophony, 410 Coloring-matters, 414 Combination, chemical, 38, ^0 by volume, 44 Combining proportions, 42, 173, 257, 445, 497 Combustible, 21 Combustion, 21 analysis for carbon and hy- drogen, 525 et seq. for nitrogen, 525, 527 definition of, 48 supporters of, 21 Composition of atmosphere, 24 bismuth salts, 225 oils and fats, 400 Compound, chemical, 27 difi’erent from mechani- cal, 32 definition of, 50 Compounds, 13, 32 of the elements, 51 Condensation, 108 Condenser, 108 Condensing tub, 108 worm, 108 Condy’s disinfecting fluids, 64, 205 Confections, 442 Conia, conine, or oonicine, 351 Conii folia, 352 fructus, 352 Conium maculatum, 352 Constant proportions, law of, 42 Construction of formulae, 36, 47, 54, 360 Constitution of alkaloids, 338 of salts, 44. 104, 235, 253, 267 of visible matter, 33 Convolvulin, 369 Convolvulinol, 369 Convolvulus scammonia, 371 Conylia, 352 Copaiba, 411 impurities in, 411, 543 Copaiva, 411 oil, 411 Copaivic acid, 411 Copper, 166 acetate of, 168 ammonio-sulphate of, 153, 169, 182 analytical reactions of, 168, 420 antidotes to, 170 arseniate of, 153 48 * 570 INDEX. Copper — arsenical, 149 arsenite of, 153 black oxide of, 167 blue, 416 coinage, 167, 467 derivation of word, 29 detection of arsenicum in, 149 foil, 167 hydrate of, 169 iodide of, 245 in organic mixtures, detection of, 420 melting-point of, 416 metallic, 167 oxide of, 167 oxyacetate of, 168 pyrites, 166, quantitative estimation of, 509 quantivalence of, 167 subacetate of, 168 sulphate of, 168 sulphate of anhydrous, 168 sulphide of, 168 Copperas, blue, 121 green, 121 Coptis trifolia, 351 Coriander oil, 407 Coriandri fructiis, 407 Coriandrum, 407 Cork-borers, 16 Correction of the volume of a gas for pressure, 469 for temperature, 469 Corrosive sublimate, 172, 176 test for in calomel, 178 Cotton-wool, 359 Cows’ milk, 397 Cream, 397 Cream of tartar, 285 Creasol, 392 Creasote, 392 Creasotum, 392 impurities in, 543 Cresol, 392 Ciesylic acid, 392 Creta, 94 prceparata, 94 Crocus (mineral), 129 (vegetable), 415 Crocus salivas, 415 Croton oil, 403 Crotonate of glyceryl, 403 Crucibles, 57 Crude antimony, 155 potashes, 54 Crum’s test for manganese, 207 Cryolite, 334 Cryptophanic acid, 429 Cryptopia, 341 Crystallization, water of, 70 Crystalloid bodies, 537 Cubeba, 353 Cubeb pepper, 353 Cubebs, oil of, 407 Cubic inches in 1 gallon, 431 Cubic nitre, 252 Cudbear, 416 Cupel, 513 Cupellation, estimation of silver by, 513 Cupr-diammon-diammonium, sul- phate of, 182 Capri subacetas, 168 sulphas, 168 sulphas, impurities in, 543 Cupric arsenite, 153, 169 compounds, 168 ferrocyanide, 169 hydrate, 169 oxide, 167 sulphate, 168 sulphide, 168 Cuprous iodide, 168, 246 oxide, 168, 361 Cuprum, 29, 156 ammonialurn, 169 Curcuma longa, 415 Curcumin, 415 Curds, 362, 397 and whey, 362, 397 Caspar ice cortex, 355 Cusparin, 355 Casso, 411 Cyanates, 300 Cyanic acid, 300 Cyanide of mercury, 248 nickel, 209 potassium, 248 silver, 194 Cyanides, 247 analytical reactions of metal- lic, 250 antidote to, 251 double, 248 quantitative estimation of, 486 INDEX. 5n Cyanogen, 247, 515 Cyanurets, vide Cyanides Cy still, 433 Dalton’s atomic theory, 43 Daphne laureola, 411 mezereuin, 411, Daturia or datiirine, 350 Dauglisli’s bread, 362 Davy’s safety-lamp, 21 Deadly nightshade, 350 Decantation, 93 Decimal coinage, 455 weights, 454, 457 Decoctions, 442 Decrepitation, 330 Decolorizing power of animal charcoal, 95 Definition of chemical action, 32 a chemical compound, 48 a chemical equation or dia- gram, 49 a chemical symbol, 49 a gas, 49 a liquid, 49 a mixture, 48 an atom, 48 an element, 48 a solid, 49 atomic weights, 50 chemical force, 48 chemistry, 48 combustion, 48 law of dififusion, 49 molecular weights, 50 quantivalence of atoms, 50 Deflagrating flux, 335 Deflagration, 62 Deliquescence, 73 Density, 464 of vapors, 470 Deodorizers, 25 Deodorizing liquid. 111 Deposits, urinary, 432 Derivation of names of elements, 27 et seq. Derivatives of ammonium, 182 Desiccation, 498, 500, 519 Destructive distillation, 109 Detonation, 62 De Valangin’s solution, 145 De Vry’s process for estimating the purity of commercial qui- nine, 529 Dextrine, 357 Dextroracemic acid, 285 Dextrose, 363 Dextrotartaric acid, 285 Diabetic urine, 362, 430, 534 Diagram, chemical, definition of, 49 Diagrams, chemical, 38, 54 Dialysis, 537 Diamines, 339 Diamond, 26 Dibasic acids, 337 Dibasylous radicals, 337 Didymium, 551 Diethylamine, 339 Diethylia, 339 Diffusion, 22 law of, definition of, 49 Digitalin, 367 Digitalinum, 367 Digitaliretin, 368 Digitalis folia^ 368 Dill oil, 406 Dinitrocellulin, 359 Dipterocarpus tnrhinatus, 412 Disinfectant, chlorine as a, 25 Disinfectants, 25 Disinfecting fluid, Burnett’s, 111 carbolic acid, 391 Condy’s, 64, 205 powder, 96 Distillation, 108 destructive, 109 dry, 109 fractional, 372 Distilled vinegar, 2i35 Dithionic acid, 307 Dolomite, 99 Donovan’s solution, 174 Dorema ainmoniacMin, 412 Double chloride of aluminium and sodium, 116 cyanides, 248 salts, 65 Dover’s powder, 352 Drachm, 460 Draconyl, 413 Dried alum, 117 Drugs, 15 Dry distillation, 109 Drying apparatus, 498, 500, 519 oils, 402 precipitates, 498, 500, 503, 519 572 INDEX. Dryobalanops aromatlca^ 409 Dulcamara, 353 Dyads, 104 Dyers’ saffron, 415 Dyeing, 117, 258 by mordants, 117 Dynamic electricity, production of, 110 Dynamicity, 47 Earth, bone-, 94 Earthenware, 314 Earths, alkaline, 108 Eau de Cologne, 406 Ebonite, 414 Echallii fructus, 349 “Effervescing citrate of magne- sia,” 289 citro-tartrate of sodium, 73 potash-water, 59, 500 soda-water, 71 Efflorescence, 73 Egg, white of, 396 yolk of, 396 Elseometer, 466 Elseoptens, 405 Elaterin, 859 Elateriuin, 359 impurities in, 543 Elder-flower oih 408 Electricity, production of dyna- mic, 110 Elementary particles, 33 Element, definition of, 48 Elements, 13, 14, 27 and their compounds, 51 classification of, 86, 104, 107, 230 classification of according to analogy, 86 classification of according to quantivalence, 104 etymology of names of, 27 of medical or pharmaceutical interest, 14 metallic, 15 non-metallic, 15 of pharmaceutical interest, 14 symbols of, 27, 37 symbols, atomic values, and weights of the, 551 symbols of, and derivation of names of, 27 et scq. Elemi, 412 Elm bark, 318 Emetia, 352 Emetine, 382 Empirical formulae, 373 Emplastra, 411 Emplastrum ceraii saponis, 265 plumhi, 188 plumbi iodidi, 188 Emulsin, 366, 393 Emulsion, 413 Enemas, 442 English red, 415 blue, 416 Epsom salt, 100 Equation, chemical, definition of, 49 Equations, 40 Equivalence, 44 Equivalents, 551 Equisetic acid, 295 Ergot, 411 Ergota, 411 Ergotin, 411 Erlangen blue, 416 Erythroretine, 300 Erucic acid, 404 Eseria, 353 Essence of aniseed, 405 apple, 389 greengage, 390 melon, 390 mirbane, 391 mulberry, 390 pineapple, 390 quince, 390 peppermint, 406 Essences, 405 Essentia anisi, 405 menthce piperitce, 406 Essential oils, vide Oils. Estimation of weight, 452 Etching, 304 Ethal, 402 Ether, 376 nitrous, 378 Ethereal salts, 381 oil, 394 Etherol, 394 Ethers, 381 Ethiops mineral, 182 Ethyl, 374, 380 acetate of, 374 butyrate of, 389 hydrate of, 374 INDEX. 573 Ethyl- hydride of, 380 iodide of, 380 nitrite of, 278 oenanthylate of, 390 oxide of, 374 pelargonate of, 390 sebacate of, 390 suberate of, 390 sulphate of, 374 zinc, 380 Ethylamine, 339 Ethylene, 394 Ethylia, 339 Ethylic alcohol, 374 Etymology of names of elements, 28 Eucalyptol, 407 Eucalyptus globulus^ 407 Euchlorine, 263 Eudiometry, 336 Eugenic acid, 407 Engeiiin, 407 Euodic aldehyd, 408 Euxanthate of magnesium, 415 Evaporation, 58, 86, 498, 500 in vacuo ^ 500 Everitt’s yellow salt, 249 Examinations of the Pharmaceuti- cal Society of Great Britain, 41 {vide Prefatory matter). Expansion on diluting solution of ammonia, 77 Explosions of gases, 20 Extracts, 442 Extr actum cannabis^ 411 filicis liquidum^ 403 Saturnij 187 Face-rouge, 300, 416 Faeces, 429 Fahrenheit's thermometer, 448 Farina tritici, 356 Fat-acids, 404 Fats and oils, composition of, 400 Fats, etc., to determine the melt- ing-point of, 450 analysis of, 539 Fatty bodies, 400 Eel bovinum purijicatum, 401 purijicatum, impurities in, 543 Felspar, 335 Fennel oil, 407 Fermentation, 362 Fermentum, 372 Fer reduit^ 135 Ferrate of potassium, 120 Ferri acetis tinctura, 127 arsenias, 123 arsenias, impurities in, 543 carbonas, 122 carbonas saccharata^ 122 carbonas saccharata, impuri- ties in, 543 citras, 130 et ammonice citras, 131 et ammonice citras, impurities in, 543 et ammonice citras^ quantita- tive estimation of iron in, 507 et ammonice sulphas^ 117 et ammonice tartras, 133 et potassce tartras, 133, 288 et quince citras, 131 et quinice citras, impurities in, 543 et strychnice citras, 133 ferrocyanidum, 303 hypophosphis, 306 iodidum, 27, 184 lactus, 309 oxalas, 282 oxidum magneticum, 133 oxidum maqneticum, impurities in, 544 perchloridi, liquor, 126 pernitratis, liquor, 135 per oxidum liumidum, 129 peroxidum hydratum, 128 peroxidum hydratum, impuri- ties in, 544 persulphatis, liquor, 127 phosphas, 120 phosphas, impurities in, 544 potassio- tartras, 130 j)ulvis, 135 pyropliosplios, 136 subcarbonas, 122 sulphas, 121 sulphas, impurities in, 544 sulphas exsiccata, 121 sulphas granulata, 121 sulphas granulata, impurities in, 544 sulphur etum, 124 Ferric acetate, 127 chloride, 125 574 INDEX. Ferric — hydrate, 128 hypophosphite, 306 iodate, 264 nitrate, 134 oxide, 129 oxide, from phosphates and oxalates, separation of, 333 oxyiodate, 264 oxysulphate, 122 peroxyhydrate, 128 pyrophosphate, 136 salts, 125 salts, analytical reactions of, - 136 sulphate, 127 sulphocyanate, 138 Ferridcyanide of potassium, 137., 303 Ferridcyanides, 303 Ferridcyanogen, 138, 303 Ferrocyanide of potassium, 248 802 of zinc, 114 Ferrocyanides, 303 Ferrocyanogen, 138, 302 Ferro-ferric hydrate, 133 oxide, 133 Ferrous arseniate, 123, 492 bromide, 124 carbonate, 1 22, 492 chloride, 126 iodide, 124 phosphate, 123 salts, 121 salts, analytical reactions of, 136 sulphate, 121 sulphide, 124, 136, 137 Ferriim, 29, 119 redacturn, 135 taj'taratum, 133, 288 tartaratum, estimation of iron in, 507 tartaratum, impurities in, 544 Fibrin, 396 vegetable, 398 FicuSj 362 elasiica, 413 Fig, 362 Filix mas, 403 Filter, to dry, 498 Filtering-paper, 93, 497 Filters, 93, 497 Filtrate, 106 Fine gold, 218 Fire-clay, 177 Fire-damp, 382 Fixed and volatile oils, difference between, 405 oils, 400 Flame, oxidizing, 331 reducing, 331 structure of, 21 Flare, 401 Flaxseed, 402 Fleitmann’s test for arsenicum, 150 Flexible collodion. 360 Flint, 314 Flores zinci, 113 Flour, 355 Flowers of sulphur, 269 Fluid magnesia, 101 Fluoric acid, 304 Fluoride of boron, 297 calcium, 90 calcium, in bones, 94, 304 silicon, 305 Fluorides, 304 Fluorine, 305 derivation of word, 30 Fluor-spar, 304 Foeniculi fructus, 407 Foil, copper, 167 Food, analysis of, 539 elements of, 398 how disposed of in the bodies of animals, 429 Force, chemical, 34 Forge-scales, 134 Formates, 301 Formic acid, 301, 401 Formica rufa, 301 Formula, chemical, definition of, 49 ofllcial, 25 officinal, 25 Formulae, 39, 40, 528 construction of, 47, 53 empirical, 373, 528 graphic, 115 rational, 373, 528 Fousel oil, 3S9 Fowler’s solution, 144 Foxglove, 367 Fraxinus orniis, 361 Fractional distillation, 371 INDEX. 575 Frankincense, 412 Frankland’s graphic formulae, 115 Freezing-mixture, 272 French chalk, 417 turpentine, 407 Fruit essences, 389 Fuchsine, 417 Fume-cupboard, 81 Fuming sulphuric acid, 277 Funnel-tubes, 81 “Fur” in water vessels, 281 Furniture of a laboratoiy, xii. Fusel oil, 389 Fusibility of metals, table of the, 451 Fusible white precipitate, 181 Fusing-points of fats, 451 Fustic, 414 Galactometer, 466 Galhanum, 412 Galena, 185 argentiferous, 191 Galenical preparations of the Bri- tish Pharmacopoeia, 442 Galipot, 410 Galla, 317 Gallic acid, 318 Gall of the ox, 401 Gallon, 460 Galls, Aleppo, 317 English, 317 Gall-stones, 441 Galvanic test for mercury, 183 Galvanized iron, 109 Gambir, 318 Gamboge, 412, 414 Gambogic acid, 412 Garancin, 415 Garcinia morella, 412 Garlic, essential oil of, 393 Gas-analysis, 319, 336 a, definition of, 49 -burners, 16, 17, 21 for balloons, coal-, 21 illuminating, 368 -lamp, 17, 21 Gases and vapors, density of, 447, 469 collection of, 16, 17 correction of the volume of, 469 for pressure, 469 for temperature, 469 Gases and vapors — diffusion of, 22 law of solubility of, in liquids, 71 relation of, to liquids and solids, 38 specific gravity of, 469 Gastric juice, 399 artificial, 399 Gaultheria procumbensy 390 Gaultheric acid, 390 Gelatine, 398 vegetable, 358 Gelatinous substances, 398 Gentiance radix, 355 German silver, 208 Ginger oil, 408 Girdwood and Rogers’s method for detecting strychnia, 424 Glacial acetic acid, 266, .451 phosphoric acid, 294 Glass, 314 liquor, 315 rods, 93 soluble, 315 tubes, to bend, 16 to cut, 16 to draw out, 93 Globulin, 396 Glucinum, 551 Glucose, 362 Glucosides, 365 Glue, 398 Gluten and glutin, 356 Glyceric alcohol, 394 Glycerine, 394, 188 Glycerines, 394 Glycerina, 394 impurities in, 544 Glyceritum acidi carholici, 395 acidi gallici, 395 acidi tannici, 317, 395 picis liquidce, 395 sodii horatis, 395 Glyceryl, 394, 400 caproate of, 402 caprylate of, 402 crotonate of, 403 hydrate of, 394, 400 laurate of, 402 margarate of, 402 myristate of, 402 oleate of, 400 palmitate of, 402 676 INDEX Glyceryl — ricinoleate of, 403 rutate of, 402 tristearate of, 400 Glycholates, 401 Glycocine, 401 Glycocoll, 401 Glycol, 394 Glycols, 394 Glycyl, 394 Glycyrrhizce radix, 364 Glycyrrhizin, 364 Gold, 216 analytical reactions of, 218 coin, 217, 467 derivation of word, 31 earth, 216 fine, 218 jewellers’, 217 leaf, 217 mosaic, 216 ochre, 414 perchloride of, 217 sulphide of, 218 yellow, 414 Goldthread, 351 Gossypium, 359 Gothite, 129 Goulard’s cerate, 187 extract, 187 water, 1S7 Graham’s dialytic process, 537 law of diffusion, 22 Grain, 453 Grains, 453 Gramme, 455 relation of, to grains, 457,4 Granati fructus cortex, 318 radicis cortex, 318 Granite, 116 Granulated tin, 214 phosphorus, 293 zinc, 19 Grape-sugar, 361 Graphic formulae, 115 Graphite, 26 Gravel, 432 Gravimetric analysis, 446, 497 Gravitation, 452 Gravity, 452 Gray powder, 171 Green copperas, 121 chloride of iron, 125 iodide of iron, 124 Green — iodide of mercury, 173 pigments, 416 sulphate of iron, 121 vitriol, 1 21 Greengage essence, 390 Griffitli’s mixture, 123 Group tests, 231 Guaiaci lignum, 369 resina, 369 Guaiacin, 369 Guaiacol, 392 Guaiacum, resin of, 369 Guaiaretin, 369 Guaiaretinic acid, 369 Guano, 320 Guarana, 353 Gum, 358 -acacia, 97, 357 -arable, 97, 357 British, 357 cherry-tree, 358 -resins, 412 tragacanth, 358 Gummate of calcium, 97, 357 lead, 97 Gummic acid, 357 Gun-cotton, 359 Gun metal, 213 Gunpowder, 258 Gutta percha, 413 Gypsum, 90 Hgematin, 396 Haematite, brown, 119 red, 119 Hcematoxyli lignum, 318, 416 Haematoxylin, 318, 416 Half-sovereign, weight of the, 217 Haloid salts, 254 Hambro’ blue, 416 Hardness of water, 281 Hard soap, 400 Heat, latent, 71 source of, 16 Heavy carbonate of magnesium, lor magnesia, 102 spar, 87 white, 87, 417 Heberden’s ink, 138 Hectare, 455 Hellebore, 354 Hemidesmi radix, 301 INDEX. 5n Hemidesmic acid, 301 Hemlock, 352 Hempseed calculi, 441 Henbane, 352 Hesperidene, 406 Hevea siphonia Braziliensis^ 413 Heterologous series, 382 Hexyl, 381 Hippuric acid, 301, 433, 436 Hips, 363 Hoflfner’s blue, 416 Homologous series, 382, 404 Honey, 363 dew, 364 Hop, 412 essential oil of, 412 Ilordeum decor tic alum ^ 356 Horeliound, vide Marrubium Horsemint, 409 Horseradish oil, 382, 406 Hubbuck’s oxide of zinc, 113 Humulus lupulus, 412 Hydrargyri chloridum corrosivinn, 176 chloridum mite^ 177 cyanidum^ 248 iodidum ruhrum, 174 iodidum ruhrum^ impurities in, 544 iodidum viride, 172 iodidum viride, impurities in, 544 nitrati acidus liquor, 175 nitratis liquor, 175 oxidum Jlavum, 179 oxidum ruhrum, 178 oxidum ruhrum, impurities in, 544 perchloridum, 176 suhchloridum, 177 suhchloridum, impurities in, 544 sulphas, 175 sulphas Jiava, 176 sulphas, impurities in, 544 sulphuretum cum sulphure, 182 sulphuretum cum sulphure, im- purities in, 544 sulphuretum ruhrum, 182 unguentum, 171 Hydrargyrum, 29, 170 impurities in, 544 ammoniatum, 181 ammoniatum, impurities in,544 49 Hydrargyrum — cum creta, 171 cum creta, impurities in, 544 Hydrated peroxide of iron, 129 substances, 70 Hydrate of aluminium, 117 ammonium, 76 benzoyl, 299 cadmium, 222 calcium, 92 cetyl, 402 chromium, 212 cobalt, 207 glyceryl, 402 manganese, 206 nickel, 209 potassium, 53 sodium, 68 zinc, 114 Hydrates, composition of, 54, 70 Hydraulic cement, 314 Hydric acetate, chloride, nitrate, sulphate, etc., vide the respec- tive acids — acetic, hydrochloric, etc. Hydride of antimony, 160 arsenicum, 149 benzoyl, 366, 413 cinnamyl, 413 copper, 307 ethyl, 382 methyl, 382 phosphorus, 306 silicon, 315 Hydrides, 105, 382 Hydriodic acid, 243 Hydrium, 19 Hydrobromic acid, 241 Hydrocarbons, 405 Hydrochlorate of morphia, 340 Hydrochloric acid, 26, 238 acid, analytical reactions of, 240 acid, antidote to, 241 acid, common, 238 dilute, 238 acid in organic mixtures, de- tection of, 418, 421 acid, volumetric estimation of, 484 Hydrocotarnine, 341 Hydrocyanic acid, 247 acid, analytical reactions of, 250, 421 578 INDEX. Hydrocyanic— - acid, antidotes to, 251 acid, dilute 249 acid from bitter almond and cherry -laurel, 366 acid in organic mixtures, de- tection of, 421 acid in the blood, 251 acid, Schonbein’s test for, 252 acid, volumetric estimation of, 486 Hydroferridcyanic acid, 303 Hydroferrocyanic acid, 302 Hydrofluoric acid, 304 Hydrogen, 18 antimoniiiretted, 160 arseniuretted, 149 benzoate, borate, etc., vide the respective acids, benzoic, boracic, etc. combustion of, 19 derivation of word, 28 explosion of, 20 functions of, 104 in artificial light-producers, 21 lightness of, 21 peroxide of, 88 persulphide of, 271 phosphoretted, 305 preparation of, 19 properties of, 19 quantitative estimation of, in organic compounds, 525 et seq. salts of, 235 siliciuretted, 316 sulphuVetted, 81, 270 used for balloons, 21 weight compared with air, 22 weight of 1 litre, 470 weight of 100 cubic inches, 470 Ifydrogenium, 19 Hydrometers, 466 Hydrosulphuric acid, 270 Hydrosulphyl, 270 Hydrous chloral, 387 Hydrous compounds, 70, 102 Hydroxyl, 270 Hygiene, 14 Hyoscyamia, 352 II goscy ami folia ^ 352 semen^ 352 I Hyoscyamine, 352 Hyper-, meaning of, 125 Hypo-, meaning of, 308 Hypobromites, 242 Hypochloride of sulphur, 272 Hypochlorite of calcium, 96 sodium, 72 Hypochlorites, 260 Hypochlorous acid, 260 Hypophosphite of iron, 306 of potassium, 306 Hypophosphites, 305 Hypophosphorous acid, 305 Hyposulphite of calcium, 305 ' sodium, 307 sodium, standard solution of, 493 Hyposulphites, 307 Hyposulphurous acid, 307 -ic, meaning of, 63, 120 Iceland moss, 300 Icthyocolla^ 398 -ide, meaning of, 63 Igasuria,"348 Ignatia, 347 Ignition, 86 Illicium anisatum^ 406 Illuminating agents, analysis of, Inch, 460 Incineration, 86 of filters in quantitative ana- lysis, 497, 503 Indelible ink, 193 Indian hemp, 411 ink, 417 red, 415 rubber, 413 rubber, vulcanized, 414 yellow, 415 Indican, 258 Indiglucin, 258 Indigo, 258 sulphate of, 258 -blue, 258 -white, 258 Indigogen, 258 Indigotin, 258 Indium, 551 Infusible white precipitate, 182 Infusions, 442 Inhalation of chlorine, 25 coniue, 352 INDEX. 579 Inhalation of — hydrocyanic acid, 249 Inhalations, 442 Ink, black, 138, 318 Heherden’s, 138 indelible, 193 Indian, 417 invisible, 208 marking, 193 printer’s, 417 sympathetic, 208 Inorganic chemistry, 338 compounds, 338 Introduction, 13 Inverted sugar, 363 lodate of potassium, 61, 263 lodates, 263 Iodic acid, 263 Iodide of arsenicum, 143 cadmium, 221 ethyl, 380 hydrogen, 243 iron, 27, 124 lead, 188 potassium, 61 silver, 194 sulphur, 244 Iodides, 243 analytical reactions of, 244 of mercury, 172, 181 quantitative estimation of, 514 separation of, from bromides and chlorides, 246 Iodine, 27, 243 chloride of, 244 derivation of word, 28 its analogy to chlorine and bromine, 243 solution of, 244 standard solution of, 488 tincture of, 244 volumetric estimation of, 493 -water, 244 Iodoform, 374, 386 lodum, 243 impurities in, 544 lodinium, 243 Ipecacuanha, 352 Ipomoea turpethum, 176 Iridium, 221, 551 Iris Jlorenlina, 407 Irish moss, 358 Iron, 119 Iron — acetate of, 127 alum, 117 ammonio-citrate of, 131 amrnonio-tartrate of, 133 analytical reactions of, 136 arseniate, 123, 147 arseniate of, volumetric esti- mation of, 492 black hydrate of, 133 black oxide of, 134 bromide of, 124 carbonate of, 122, 492 cast, 119 chlorides of, 125 compounds, nomenclature of, 120 derivation of word, 29 detection of, in presence of aluminium and zinc, 138 galvanized, 109 hydrated peroxide of, 128 hypophosphite of, 306 in official compounds, estima- tion of, 492, 507 iodate of, 264 iodide of, 27, 124 lactate of, 309 magnetic oxide of, 133 magnetic oxide of, estimation of iron in, 492 nitrate of, 134 ore, magnetic, 119 ore, needle, 129 ore, spathic, 119 ore, specular, 119 oxide of, 134 oxy hydrates of, 129 oxysulphate of, 122 perchloride of, 125 perhydrate of, 128 pernitrate of, 135 peroxide of, 129 peroxyhydrate of, 129 persulphate, of 127 phosphate of, 123 phosphate of, volumetric esti- mation of, 492 from phosphates and oxa- lates, separation of per- oxide of, 332 potassio-citrate of, 130 potassio-tartrate of, 133 pyrites, 119 580 INDEX. Iron- pyrophosphate, 136 quantitative estimation of, 492, 507 and quinine, citrate of, 131, 344, 532 red oxide of, 129 reduced, 135 rust of, 119 saccharated carbonate of, 122 saccharated carbonate of, vo- lumetric estimation of, 492 salts, nomenclature of, 120 scale compounds of, 130 separation of, from alumin- ium and chromium, 213 sodio-citrate of, 130 sodio-tartrate of, 130 -stone, clay, 119 suhcarbonate, 122 subsulphate, 127 sulphate of, 121 sulphide of, 124 sulphocyanateof, 130,138,251 tersulphate of, 127 wrought, 119 Isinglass, 398 Isomerism, 358 Isomorphism, the doctrine of, 46 Isoraorphous bodies, 46, 295 Isonandra gutta^ 414 -ite, meaning of, 60 Ivory-black, 417 Jalap resin, 369 Jalapa^ 369 Jalapce resina, 369 resina, impurities in, 544 Jalapic acid, 369 Jalapin, 369 Jalapinol, 369 Jaune hrillant, 222 Jelly, 398 vegetable, 358 Jervia, 354 Jervine, 354 Juices, 442 Juniper-oil, 407 Juniperus, 407 Kalium, 28 Kamala^ 411 Kelp, 243 Kermes, mineral, 158 Kilbride mineral, 129 Kiln, 91 Kilogram, 456, 457 Kilolitre, 462 Kilometre, 456 Kinate of quinia, 343 King’s blue, 416 Kino, 318 Kola-nut, 353 Kousso, 411 Kramer ice radix ^ 318 Laboratory furniture, x. Lac, 397 Lac-dye, 416 Lactates, 309 Lactic acid, 309 Lactometer, 397 Lactose, 362 Latuca, 355 Lactucin, 355 Lsevogyrate, 363 Lsevoracemic acid, 285 Lsevorotation, 363 Laevotartaric acid, 285 Lsevulose, 363 Lakes, 118 Lampblack, 417 Lamps, gas-, 16, 21 Lana philosophica, 114 Lanthanium, 551 Lard, 401 benzoated, 401 prepared, 401 Larix europcea, 408 Latent heat, 71 Laudanine, 341 Laudanosine, 341 Laughing-gas, 257 Laurate of glyceryl, 402 Laurel-camphor, 409 Laurie aldehyd, 408 Laurie acid, 404 Laurocerasi folia, 366 Lavender-oil, 407 -water, 406 Lavender, oil of, 407 Law, Avogadro’s and Ampere’s, 44, 45 of chemical combination by weight, 40 et seq., 49 by volume, 44 et seq., 49 concerning molecular weight, 46, 237, 471 INDEX. 581 Law — of constant proportions, 41, 445, 497 of diffusion, definition of, 49 multiple proportions, 42, 176, 257 reciprocal proportions, 41 solubility of gases in liquids, 71 Laws of chemical combination, 40, 44, 49 Lead, 185 acetate of, 186 analytical reactions of, 189, 420 antidotes to, 190 carbonate of, 185 chloride of, 189 chromate of, 189 derivation of word, 29 gummate of, 97 hydrato-carbonate of, 185 in organic mixtures, detection of, 420 iodide of, 188 nitrate of, 187 oleate of, 188 oxide of, 185 oxyacetate of, 187 oxychromate of, 189 plaster, 188 puce-colored or peroxide of, 187 quantitative estimation of, 478, 512 red, 187, 415 shot, 185 subacetate of, 186 sugar of, 186 sulphate of, 190 sulphide of, 189 native, 185 test for, in water, 189 -tree, 190 volumetric estimation of solu- tions of acetate of, 478 white, 185 Loadstone, 119 Leaf-green, 416 Lecanora, 416 Legumin, 398 Lemon- chrome, 189 -juice, 290 -oil, 406 Length unit, 455 Lentish tree, 411 Lepidolite, 201 Levulose, 363 Lichen blue, 416 Light carbonate of magnesium, 100 carburetted hydrogen, 382 magnesia, 102 Lignin, 359 Lime, caustic, 91 chloride of, 96 -kiln, 91 -oil, 406 quick, 91 slaked, 91 superphosphate of, 292 -water, 92 Limestone, 90 magnesian, 100 mountain, 100 Limonis cortex, 406 succus, impurities in, 544 Limonite, 129 Line, 460 Lini farina, 402 semina, 402 Liniment of mercury, 171 Liniments, 442 Linimentum amrnonice, 401 colds, 401 Linum, 402 Linseed, 402 -cake, 402 oil, 402 Liqueurs, 372 Liqiiidambar orientale, 413 Liquid camphor, 409 definition of, 49 Liquids, specific gravity of, 464 official, specific gravity of, 464 Liquor amrnonice, 77 amrnonice, impurities in, 544 ammonioe citratis, 79 amrnonice fortior, 77 amrnonice fortior, impurities in, 544 ammonii acetatis, 78 antimonii chloridi, 155 aniimonii cJdoridi, impurities in, 544 antimonii chloridi, estimation of antimony in, 509 arsenicCtlis, 144 49 * 582 INDEX. Liquor — arsenicaU&, impurities in, 544 arsenici chloridi, 145 arsenici et hydrargyri iodidi^ 143 arsenici hydrochloricus, 145 arsenici hydrochloricus, impu- rities ill, 544 atropioi, 350 atropice sul})hatis, 350 bismuthi et ammonice citratisj estimation of bismuth in, 225 bismuthi et ammonice citratis, impurities in, 544 calcis, 92 calcis, impurities in, 544 calcis chloratce^ 96 calcis chloratce^ impurities in, 545 calcis saccharatuSj 92 calcis saccharatusj impurities in, 545 chi or i^ 240 chlori, impurities in, 545 fei'ri citratis^ 130 ferri perchloridi, 126 ferri perchloridi fortior^ 126 ferri perchloridi fortior^ impu- rities in, 545 ferri perchloridi fortior, esti- mation of iron in, 508 ferri pernitratis, 135 ferri pernitratis, impurities in, 545 ferri pernitratis^ estimation of iron in, 508 ferri persulphatis, 137 ferri persulphatis, impurities in, 545 ferri persulphatis, estimation of iron in, 508 ferri subsulphatis, 127 ferri tersulphatis, 127 gut ta-per dice, 414 hydrargyri nitratis acidus, 175 hydrargyri nitratis acidus, im- purities in, 545 hydrargyri perchloridi, 177 iodi, 244 iodinii compositus, 244 lithice effervescens, 201 hihice effervescens, impurities in, 545 Liquor — magnesicB carbonatis, 101 magnesice carbonatis, impuri- ties in, 545 magnesii citratis, 102 morphice acetatis, 341 morphice hydrochloratis, 341 morphice, sulphatis, 341 plumbi subacetatis, 187 plumbi subacetatis, impurities in, 545 jdumbi subacetatis dilutus, 187 potasses, 53, 56 potasses, impurities in, 545 potasses effervescens, 59 potasses effervescens, impuri- ties in, 545 potasses, neutralizing power of, 478 potasses, specific gravity of, 466 potasses, to prepare pure, 56 potassii arsenitis, 144 potassii citratis, 60 potassii permanganatis, 204 sodes, 68 sades, impurities in, 545 sodes chlorates, 72 sodes chlorates, impurities in, 545 sodes chlorinates, 72 sodes effervescens, 71 sodes effervescens, impurities in, 545 sodii arseniatis, 146 strychnies, 248 zinci chloridi, 112 Liquorice-sugar, 364 List of apparatus, ix. of chemicals, xi. of reagents, x. Litharge, 185 Lithates, 320 Lithii carbonas, 201 carbonas, impurities in, 545 citras, 200 citras, impurities in, 545 Lithic acid, 320 Lithium, 200 analytical reactions of, 201 carbonate of, 201 citrate of, 200 derivation of word, 30 flame, 201 INDEX. 683 Lithium — fluoride of, 201 silicate of, 201 sulphate of, 201 urate of, 201 Litmus, 83, 416 paper, 83 solution of, 83 tincture of, 83 Litre, relation of, to pints, 456 Liver of sulphur, 56 Lixiviation, 73 Loadstone or lodestone, 119 Lobelia^ 352 Lobelia vinegar, 265 Lobelina, 352 Lobeline, 352 Logwood, 25, 415 solution of bleached, by chlo- rine, 25 Long pepper, 351 Looking-glasses, 214 Lotio hydrargyri Jlava, 179 hydrargyri 179 Louisa-blue, 416 Lozenges, 442 Lucifers, 22 Lump-sugar, 361 Lunar caustic, 193 Lupuliu, 412 oleo-resin of, 41 2 LupuliiSj 412 Luteolin, 415 Luting, 82 fire-clay, 177 linseed meal, 82 Lycopodium, 403 Mace, 407 oil of, 407 Mads, 407 Madder, 415 Magenta, 417 Magnesia, 102 effervescing citrate of, 289 impurities in, 545 calcined, 102 fluid, 101 hydrous carbonate of, 102 Magnesia levis, 102 levis, impurities in, 545 Magnesian limestone, 100 Magnesii carbonas, 100 carbonas, impurities in, 545 Magnesii — carbonas levis, 100 carbonas levis, impurities in, 545 carbonatis, liquor, 101 sulphas, 100 sulphas, impurities in, 545 Magnesite, 100 Magnesium, 99 analytical reactions of, 102 and ammonium, arseniate of, 103 and ammonium, phosphate of, 102 carbonate of, 100 chloride of, 99 citrate of, 290 derivation of word, 29 detection of, in presence of barium and calcium, 106 euxanthate of, 415 for analytical purposes, 150 limestone, 99 oxide of, 102 phosphate of, in bones, 94 purrate of, 415 quantitative estimation of, 505 separation from barium and calcium, 106 silicate of, 314 sulphate of, 100, 505 sulphite of, 273 Magnetic iron ore, 119 oxide of iron, 133 Magpie test for mercury, 183 Malachite, 166 Malate of atropine, 350 nicotine, 352 Malates, 309 M^le fern oil, 403 Malic acid, 309 Malt, 357 Manganate of potassium, 63, 204 Manganese, 203 analytical reactions of, 204 black oxide of, 203 Crum’s test for, 207 derivation of word, 30 quantitative analysis of black oxide of, 506 sulphate of, 206 Manganesii oxiduin nigrum, 203 sulphas, 206 584 INDEX Manganous chloride, 204 hydrate, 206 sulphide, 206 Maniitty 364 impurities in, 545 Mannite, 364 Manufacturing chemists, 14 Manures, analysis of, 539 31aranta, 357 Marble, 90 Margarine, 402 Marine soap, 402 Marking-ink, 193 Marl, 116 Marmalade, 318 Marmor album, 90 Marsh-gas, 382 Marsh’s test of arsenicum, 149 Marruhium, 355 Maryland senna, 367 Massicot, 185 Mastic, 411 Mastiche, 411 Mastichic acid, 411 Masticin, 411 Maticce folia, 355 Matricaria chamomilla, 406 Mauve, 417 May-apple, 351 Meadow-sweet, oil of, 390 Measurement of temperature, 447 Measures, 453 et seq. Mechanical and chemical com- bination, diflference between, 27, 32 Meconate of morphine, 340 Meconic acid, 310, 424 Meconine, 341 Medicines, analysis of, 336 Meerschaum, 314 Mel, 363 impurities in, 545 horacis, 297 depuratum, 364 sodce boratis, 297 Melam, 316 Melasses, 364 Melissic acid, 404 Melting-points, Table of, 451 of fats, etc., to determine, 450 of metals, 451 Melissyl, palmitate of, 402 Melon-essence, 390 Memoranda, analytical, 230,327 Mentha piperita, 407 viridis, 407 Menthene, 407 Menthol, 407 Mercuric ammonium, chloride of, 171 .chloride, 172, 176 cyanide, 248 iodide, 172, 174 oxide, 178 oxynitrates, 175 oxysulphate, 178 , nitrate, 174 salts, 171 salts, analytical reactions of, 180, 418 sulphate, 175 sulphide, 182 Mercurius vitce, 156 Mercurous ammonium, chloride of, 181 chloride, 172, 177 chromate, 292 iodide, 172 nitrate, 174 oxide, 179 salts, 171 salts, analytical reactions of. 183 sulphate, 175 sulphide, 182 Mercury, 170 amido-chloride of, 181 ammoniated, 181 ammonio-chloride of, 181 analytical reactions of, 180 antidotes to, 184 basic sulphate of, 176 black oxide of, 179 carbonates of, 184 cyanide of, 248 chlorides of, 176 derivation of word, 29 iodides of, 172, 181 galvanic test for, 183 magpie test for, 183 native sulphide of, 170 nitrates of, 174 nomenclature of salts of, 171 of life, 156 in organic mixtures, detection of, 419 oxides of, 178 oxynitrates of 175 INDEX. 585 Mercury — oxysulpliate of, 176 oxysiilpliide of, 182 quantitative estimation of, 510 subchloride of, 177 sulphates of, 175 sulphide of, 170, 182 yellow oxide of, 179 Meta, meaning of, 215 Metaboracic acid, 297 Metacinnamein, 413 Metagummic acid, 358 Metallic elements, 15 Metalloids, 15 Metals, 15 of minor pharmaceutical im- portance, 200 quantitative estimation of, 497 Table of the fusibility of, 451 Metamerism, 358 Metantimonic acid, 157 Metaphosphates, 310 Metaphosphoric acid, 310 Metastannates, 215 Metastannic acid, 215, 258 Metastyrol, 413 Metavanadates, 295 Methenyl, 386 IVlpthyl, 381 conia, 352 hydride of, 382 salicylate, 390 Methylamine, 339 Methylated spirit, 383 sweet spirit of nitre, 384 Methylene, dichloride of, 386 Methylic alcohol, 383 detected in presence of ethy- lic alcohol, 383 Metre, 456 relation of, to inches, 456, 461 Metric system, 454 et seq, of weights and measures, its relation to the English, 456 et seq. system, weights and measures of, 455 et seq. Mezerei cortex, 411 Mezereon, 411 Mica Panis, 362 Microcosmic salt, 332 Microscopic examinations of uri- nary sediments, 433 Milk, 397 sugar, 362 sulphur, 270 Mimetesite, 295 Mimotannic acid, 318 Mineral acids, detection of in organic mixtures, 421 chameleon, 205 kermes, 158 kilbride, 129 purple, 415 rouge, 415 Minerals, general analysis of, 329 et seq. special analysis of, 549 Minim, 460 Minium, 185 Mirbane, essence of, 391 Mistura ferri aromatica, 138 ferri composita, 122 poiassi citratis, 290 Mixture, different from chemical combination, 27 definition of, 48 Mixtures, 442 Mohr’s burette, 476 Moist sugar, 361 Molasses, 364 Molecular volume, 46 weight, 46, 237, 471 weights, definition of, 50 Molecule, definition of, 48 Molecules, 36, 48 Molybdenum, 551 Molybdic acid, 427 Monads, 104 Monamines, 339 Monarda, 409 Monobasic acids, 237 Monobasylous radicals, 237 Mononitrocellulin, 360 Monsel’s solution, 127 Mordants, 117 Mori succus, 415 Morphia, or Morphine, 340 acetate of, 340 analytical reactions of, 341, 424 hydrochlorate of, 340 in organic mixtures, detection of, 424 quantitative estimation of, 533 Morphice acetas, 340 586 INDEX Morphice — hydrochloras, 340 hydroclilorasy impurities in, 546 murias^ 340 sulphas^ 340 Mosaic gold, 216 Moschusy 398 moschiferus, 298 Motion from heat, 71 Mountain-blue, 416 limestone, 99 Mucic acid, 365 Mucilage of gum acacia, 97 starch, 356 tragacanth, 97 Mucilago acacice^ 97 cunylij 356 tragacanthcB, 97 Mucus in urine, 420 Mulberry calculus, 424 -essence, 390 -juice, 415 Mulder’s process for estimating alcohol, 536 Multiple proportions, law of, 42, 173, 257 Murexid, 320 Musk, 398 deer, 298 Mustard, 393 artificial oil of, 393 essential oil of, 393 fixed oil of, 403 Myrcia acr/s, 372 Myristate of glyceryl, 402 Myristic acid, 404 Myristica^ 407 Myristicene, 407 Myristicol, 407 Myronate of potass iumV>'3; 3 Myroxylon PereircE^ 413 Toluiferaj 413 Myrrh, 412 412 Myrrhic acid, 412 Naphthalic acid, 299 Naphthalin, 299 Narceia, 341 Narcotine, 341 Narthex assafoetida, 412 ' Nataloin, 393 ' Natrium j 28 Nectandra Rodicei, 350 Nectandrce cortex, 350 Nectaudria, 351 Needle iron ore, 129 Neroli oil, 406 Neutral chromate, 89 Nickel, 208 analytical reactions of, 209 arsenio-sulphide of, 208 cobalticyanide, 210 cyanide, 209 derivation of word, 30 hydrate of, 209 separation of, from cobalt, 209 sulphide of, 209 Nicotia, nicotine, nicotina, or ni- cotylia, 352 Nicotiana tahacum, 352 Nihilum album, 113 Niobium, 507 Nitrate of ammonium, 257 argent - ammon - ammonium, 182 barium, 87 bismuth, 223 cadmium, 222 iron, 134 lead, 188 mercury, 174 potassium, 52, 253 silver, 192 silver, standard solution of, 486 sodium, 68, 253 strontium, 202 ^ Nitrates, 252 analytical reactions of, 252 quantitative estimation of,5 15 ■ " Nitre, 253 < cubic, 253 sweet spirit of, 312, 379 Nitric acid, 252 acid, antidotes to, 259 ! acid in organic mixtures, de- j tection of, 421 i acid, volumetric estimation ] of, 484 anhydride, 255, 257 oxide, preparation of, 256 peroxide, 256 i Nitrite of ethyl, 312 potassium, 311 ^ Nitrites, 311 analytical reactions of, 311 INDEX 58T Nitrobenzol, 391 in oil of bitter almonds, test for, 363 Mtrocellulin, 360 Nitrogen, 23 derivation of word, 28 in the atmosphere, 23 oxides of, 256 peroxide of, 256 preparation of, 23 properties of, 23 quantitative estimation of, in organic compounds, 527 et seq. relative weight of, 24 Nitrohydrochloric acid, 162, 255 Nitromuriatic acid, 255 Nitrous acid, 257 anhydride, 257 ether, 312 oxide, 257 Nomenclature of salts : — alkaloids, 339 anhydrides, 70 anhydrous bodies, 70 -ate, 60 bi,59 carbonization, evaporation, ignition, incineration, 86 double salts, 65 hydrates, 53 hydrous bodies, 70 hyper, 125 -ic, -ous, 59, 63, 120 -ide, -ite, 63, 120 iron salts, 120 mercury compounds, 171 per, 125 Non-drying oils, 402 Non-metallic elements, 15 Non-metals, 14 Nordhausen sulphuric acid, 277 Notation, 37 et seq. Notes, analytical, 230, 327 Nutmeg, expressed oil of, 407 oil of, 407 Nutrition, plastic elements of, 398 Nux vomica, 347 Oak-bark, 317 black, 415 Oatmeal, 356 Occlusion, 220, 221 Ochre, 414 Octohedral, 148 (Enanthylic acid, 404 Official liquids, specific gravity of, 464 substances, volumetric esti- mation of, 478, 484, 486, 489, 492, 494 Official formula, 25 Officinal formula, 25 Oil, almond, 402 amber, 315 aniseed, 406 apple, 389 bergamot, 406 bitter almond, 366 bitter almond, artificial, 391 buchu, 406 cacao, 402 cajuput, 406 cake, 402 camphor, 409 capsicum, 351 caraway, 407 cardamoms, 406 cascarilla, 407 cassia, 407 castor, 402, 403 cedra, 406 chamomile, 406 cinnamon, 407 citron, 406 citronella, 407 cloves, 407 cocoa-nut, 402 cod-liver, 402 copaiva, 407 coriander, 407 croton, 402, 403 cubeb, 407 dill, 406 elder-fiower, 408 eucalyptus, 407 fennel, 407 garlic, 393 ginger, 408 hop, 412 horsemint, 409 horseradish, 393, 406 juniper, 407 lavender, 407 lemon, 406 lime, 406 linseed, 402 lycopodium, 403 688 INDEX. Oil— male-fern, 403 meadow-sweet, 390 mustard, artificial, 393 mustard, fixed, 403 mustard, volatile, 408 neroli, 406 nutmeg, 402, 407 olive, 403 orange-flower, 406 orange-rind, 406 origanum, 407 orris, 407 pepper, 353 peppermint, 407 pimento, 407 rose, 407 rosemary, 408 rue, 408 sassafras, 408 savin, 408 spearmint, 407 sperm, 402 star-anise, 406 tlieobroma, 402 thyme, 409 turpentine, 408 valerian, 408 of vitriol, 276 wine, 394 winter-green, 390 wormseed, 408 Oils and fats, composition of, 400 Oils, analysis of, 539 drying, 402 essential, 405 fixed, 402 non-drying, 403 volatile, 405 volatile, process for, 405 Ointments, 442 Olea destillata, impurities in, 546 Oleate of glyceryl, 400 ead, 188 , 400 . gas, 394 Oleic acid, 400 Oleine, 400 Oleo-resins, 411 Oleoresina capsid^ 412 cuhehcE, 412 lupulintey 412 piper is, 412 zingiber is j 412 Oleum amygdalcB amarm, 366 arnygdaloe dulcis, 402 anethi, 406 anisi, 406 anthemidis, 406 hergamii, 406 cajuputi, 406 camphorm, 409 carui, 407 caryophylli, 407 cinnamomi, 407 copaibcE, 407 coriandri, 407 crotonis, 403 cubebcB, 407 ethereum, 394 J'ceniculi, 407 gaultherim, 390 juniperi, 407 lavendulce, 407 limonis, 406 Imi, 402 menthce piperitce, 407 menthoe viridis, 407 morrhucB, 402 myristicce, 407 myristicce expressum, 402 olivoe, 403 origani, 407 pimentoe, 407 ricini, 403 rosce, 407 rosrnarini, 408 rutce, 408 sabince, 408 sassafras, 408 sinapis, 408 succini, 315 succini rectijicatum, 315 terebinthince, 408 theobromce, 402 thy mi, 409 tiglii, 403 valeriance, 408 Olive-oil, 403 Omentum, 40^ Opal, 315 Opianine, 341 Opium, 340 Opium, detection of in organic mixtures, 424 estimation of morphia in, 532 impurities in, 546 vinegar, 265 INDEX. 689 Orange-chrome, 189 Orange-flower, 406 -flower oil, 406 -rind oil, 406 -wine, 372 Orchil, 416 Orcin, 416 Ordeal-poison, 353 Orellin, 415 Organic analysis, 525 bases, 338 chemistry, 338 compounds, 338 Orpiment, 415 Orris, butter of, 407 oil of, 407 Ortho, meaning of, 311 Orthophosphates, 312 Orthophosphoric acid, 312 Orthovanadates, 296 Os, 95 Os ustuMf 95 Osmium, 221, 551 Otto of rose, 407 Ounce, 453 -ous, meaning of, 63, 120 Ovi vitelluSj 396 Ovu77i, 396 Ox-bile, 401 -gall, 401 Oxalate of ammonium, 80 barium, 282 calcium, 282 cerium, 203 iron, 2^2 silver, 283 sodium, 283 strontium, 202 Oxalates, 282 analytical reactions of, 282, 421 from phosphates and ferric oxide, separation of, 333 quantitative estimation of,521 Oxalic acid, 282 acid, antidotes"to, 283 acid, in organic mixtures, de- tection of, 421 acid, standard solution- of, 477 Oxide of aluminium, 117 antimony, 156 calcium, 91 chromium, 210 copper, 167 50 Oxide of — iron, black, 133 lead, 185 magnesium, 102 manganese, 203 mercury, 178 silicon, 315 silver, 193 tin, 213 zinc, 113 Hubbuck’s, 113 Oxides of nitrogen, 257 Oxidizing flame, 331 Oxyacetate of, copper, 168 of lead, 186 Oxyacid salts, 252 Oxyacids of sulphur, 307 Oxycarbonate of bismuth, 224 Oxychloride of antimony, 156 Oxychromate of lead, 189 Oxygen, 15 derivation of word, 28 from ozone and antozone, 245 in the air, 15, 24 its relation to animal and vegetable life, 18 preparation of, 15 properties of, 17 quantitative estimation of, in organic compounds, 525 et seq, solubility in water, 18 specific gravity of, 22 weight of 100 cubic inches, 470 Oxygenated water, 88 Oxy hydrates of iron, 129 Oxyiodate of iron, 264 Oxymel, 364 of squill, 364 Oxynitrates of mercury, 175 bismuth, 224, 225 Oxysalts, 254 Oxysulphate of iron, 122 mercury, 176 Oxysulphide of antimony, 157 mercury, 182 Ozone, 211, 245 Palladium, 221, 551 Palm-oil, 402 Palm'ftate of cetyl, 402 4 glyceryl, 402 melissyl, 402 590 IxNDEX. Palmitic acid, 404 Palmitine, 402 Papaver rhceas^ 415 somniferurn, 340 Papaveris capsulce, 340 Papaxerine, 341 Paper, bibulous, 93 for filtering, 93, 497 Papers, test-, 83 Para, meaning of, 285 Paratartaric acid, 285 Paraguay tea, 353 Pareirce radix^ 351 Paris blue, 416 red, 415 Particles, elementary, B9 Pearlash, 53 Pearl-barley, 356 -white, 224, 417 Peas, 398 Pectin, 358 Pelargonic acid, 404 Pellitory root, 411 Pelosia, 351 Pelosine, 351 Pentacliloride of antimony, 156 Pentatliionic acid, 307 Pepper, black, 353 cayenne, 351 cubeb, 353 long, 353 white, 353 oil of, 353 resin of, 411 Peppermint oil, 407 Pepsin, 399 Per-, meaning of, 125 Perbromates, 242 Percha tree, 414 Perchlorate of potassium, 262 Perchloric acid, 261 Perchloride of gold, 217 iron, 125 platinum, 219 tin, 214 Perfumes, 406 Perhydrate of iron, 128 Permanganate of potassium, 64, 204 its use in volumetric analysis, 488 Pernitrate of iron, 134 Peroxide of barium, 88 hydrogen, 88 Peroxide of — iron, 129 iron, hydrated, 128 lead, 187 nitrogen, 256 Peroxy hydrate of iron, 128 Persian berries, 415 Persulphate of iron, 127 Persulphide of hydrogen, 271 Peru, balsam of, 413 Pervuine, 413 Petalite, 201 1 Pettenkofer’s test for presence of bile, 401 Pewter, 155, 185, 214 Phaeoretine, 300 Pharaoh’s serpent, 316 Pharmaceutical chemists, 14 Pharmaceutical Society of Great Britain, examinations of, 14 Pharmacists, 14 Pharmacy, 14 Phenic acid, 391 alcohol, 391 Phenol, 391 Phenyl, 391 Phenylamine, 393 Phosphate of ammonium, 79 barium, 295 calcium, 90, 94, 295 iron, 123, 295 magnesium and ammonium, 103 magnesium and ammonium from oxalates and ferric oxide, separation of, 333 magnesium, in bones, 94 silver, 194 sodium, 95 sodium, how prepared from phosphate of calcium, 95 Phosphates, 292 analytical reactions of, 294 quantitative estimation of, 521 Phosphites, *^12 test for, 313 Phosphomolybdic acid, 427 Phosphoretted hydrogen, 306 Phosphoric acid, 22, 293, 312 acid, diluted, 293 acid, quantitative estimation of free, 521 anhydride, 22, 310 INDEX. 591 Phosphorous acid, 312 Phosphorus, 22 coiribustion of, 22' derivation of word, 28 detection of, in organic mix- tures, 422 granulated, 293 properties of, 22 red or amorphous, 359 trihydride, 306 Phthalic acid, 299 Phyllocyanin, 416 Phylloxanthin, 416 Physostigmatis faha^ 353 Physostigma, 353 Physostigmine, 353 Picric acid, 392 Pigments, 414 Pills, 440 Pilula ferri carhonatis, 122 fen'i iodidi, 27 hydrargyria 171 hydrargyri subchloridi compo- sita, i78 plumbi cum opio^ 187 quinice, 344 Pilulce antimonii compositce, 178 ferri compositce, 123 Pimaric acid, 410 Pimento, 407 oil, 407 Pimpinella anisum, 406 Pine-apple, essence of, 390 Pinic acid, 410 Pink saucers, 416 the common, 371 Pins, 214 Pint, 460 Pinus, 408, 412 Piper nigrum, 353 Piperia, 353 Piperidia, 353 Piperidine, 353 Piperine, 353 Pistachia terebinthus, 408 Pitch, 412 burgundy, 411 Pix burgundica, 411 canadensis, 412 liquida, 412 Plants and animals, complemen- tary action on air, 18 Plaster of ammoniacum and mer- cury, 171 Plastej* of — mercury^ 171 Paris; 90, 417 Plasters, 188, 440 Plastic elements of nutrition, 398 Platiiiic salts, 219 Platinous salts, 219 Platinum, 219 analytical reactions of, 219 and ammonium, chloride of, 83, 499 and potassium, chloride of, 65 black, 220 derivation of word, 31 foil, 64, 219 perchloride of, 219 residues, to recover, 221 spongy, 221 sulphide of, 220 Plumbago, 26 Plumbi acetas, 1 86 acetas, impurities in, 546 carbonas, 186 carbonas, impurities in, 546 emplastrum, 18 iodidum, 188 nitras, 187 oxidum, 185 oxidum, impurities in, 546 subacetatis, liquor, 187 Plummer’s pills,” 178 Plumbic peroxide, 187 acetate, sulphate, etc., vide salts of lead. Plumbum , 29 Pocula emetica, 155 Podophylli radix, 351 resina, 351 Poisonous alkaloids, 423, 425 Poisons, antidotes to, vide Anti- dotes, detection of, in organic mixtures, 418 et seq» Polybasic acids, 237 Polybasylous radicals, 237 Polychroite, 415 Poiygala senega, 371 Polygalic acid, 371 Polymerism, 358 Polymorphism, 358 Polymorphous bodies, 359 Polysulphide of calcium, 270 Pomegranate root* bark, 318 Porcelain, 314 Portland cement, 314 592 INDEX Potash alum, 116 solution of caustic, 55 solution of caustic, to prepare pure, 55 sulphurated, 56 vol. estim. of sol. of, 478 -water, 56 Potashes, 52 Potassa, 56 Poiassa caustica, 56 caustica, impurities in, 546 sulphur at a,, 56 sulphurata, impurities in, 546 Potassce, vide Potassii, effervescence, liquor, 59 liquor, 53, 56 liquor, to prepare pure, 55 prussias Jiava, 248, 302 Potassic, hydrate, etc., vide salts of potassium. Potassii acetas, 57 acetas, impurities in, 546 bicarbonas, 58 bicarbonas, impurities in, 546 bichromas, 210 bitartras, 66, 284 bromidum, 63 bromidiun, impurities in, 546 carbonas, 52 carhonas pura, 53 carbonas impura, 52 carbonas, impurities in, .546 chloras, 261 chloras, impurities in, 546 citras, 60 citras, impurities in, 546 cyanidum, 248 et sodii tartras, 61, 72 ferridcyanidum, impurities in, 546 ferro cyanidum, 248 hypophosphis, 306 iodidum, 61 iodidum, impurities in, 546 nitras, 60, 252 nitras, impurities in, 546 permanganas, 64, 204 permanganas, impurities in, 546 sulphas, 60, 255. sulphas, impurities in, 546 sulphis, 270 sulphuretam, 56 tartras, 61, 62 Potassii — tartras, impurities in, 546 tartras acida, 284 tartras acida, impurities in, 546 Potassio-citrate of iron, 130 -tartrate of antimony, 157, 284 -tartrate of iron, 130 Potassium, 52 acetate of, 57 acid carbonate of, vide bicar- bonate. acid tartrate of, 65 analytical reactions of, 64 antimoniate of, 74 bicarbonate of, 58, 478 bichromate of, 210 bitartrate of, 65, 284 borotartrate of, 297 bromate of, 63 bromide of, 63, 415 carbonate of, 53, 478 chlorate of, 16, 261 chloride of, 65 chromate of, 60 and platinum, chloride of, 64 citrate of, 60 cobalticyanide of, 207 cyanate of, 300 cyanide of, 248 derivation of word, 28 ferrate of, 120 ferriclcyanide,of, 303 ferrocyanide of, 248, 301 -flame-test, 66 hydrate of, 54 hydrate, to prepare pure so- lution, 55 hypophosphite of, 306 iodate of, 62, 263 iodide of, 61 manganate of, 64, 186 myronate of, 393 nitrate of, 52, 60, 252 oleate of, 400 perchlorate of, 262 permanganate of, 64, 204 preparation of, 53 properties of, 53 quantitative estimation of, 476, 497 quantivalence of, 53 INDEX. 593 Potassium — red chromate of, 88, 210 red prussiate of, 303 and sodium, tartrate of, 72 salts, analogy of to sodium salts, 73 sodium, and ammonium, sepa- ration of, 85 sources of, 52 sulphate of, 60, 255 sulphides of, 56 sulphite of, 270 sulphocyanate of, 316 sulphurated, 56 tartrate of, 60 tartrate of, acid, 52, 65, 284 yellow chromate of, 60, 210 yellow prussiate of, 247, 301 Potato-oil, 389 Poultices, 442 Pound, 459 Powder, bleaching-, 96 Powders, 442 soda-, 73 specific gravity of, 467 Practical analysis, 84 Precipitant,* 65 Precipitate, 65 Precipitated chalk, 92 sulphur, 270 Precipitates, soluble, in solutions of salts, 231, 250 to wash, 92, 93, 490, 508 to weigh, 499, 501,503 Precipitation, 65 Preparations of the British Phar- macopoeia, chemical, 444 galenical, 44^ Prepared carbonate of calcium, 94 chalk, 94 lard, 402 suet, 402 Pressure, correction of vol. of gas for, 469 gauges, 447 Principles of Chemical Philoso- phy, 32 Printer’s ink, 417 Prismatic nitre, 252 Proportions, atomic, 41, 173 constant, 41, 49 multiple, 42, 49 reciprocal, 41, 50 Proof spirit, 373 Propenyl, 394 Propionic acid, 404 Propyl, 381, Propylamine, 339 Protopine, 341 Proximate analysis, 525 Prune, 363 Prunum, 363 Prussian blue, 303, 416 Prussiate of potash, red, 303 of potash, yellow, 248, 302 Prussic acid, 247 Pseudomorphia, 341 Pterocarpi lignum., 415 Pterocarpus santilinus, 415 Ptyalin, 438 Puce-colored oxide of lead, 187 Puddling, iron, 119 Pulvis algarothi, 156 angelicus, 156 antimonialis, 159 ipecacuanhoi compositus, 352 Pulveres efferoescentes^ 73 aperientes, 287 Purified ox-bile, 401 Purple of Cassius, 218 foxglove, active principle in, 367 Purpurine, 432 Purrate of magnesium, 415 Purree, 415 Pus, in urine, 437 Putty-powder, 215 Pyrethrin, 411 Pyrethri radix, 411 Pyrites, copper, 166 iron, 119 Pyroarseniate of sodium, 146 Pyroarseniates, 146 Pyrogallic acid, 319 acid, use of in gas analysis, 319 Pyroligneous acid, 265 Pyrolusite, 20 Pyrometers, 450 Pyromorphite, 295 Pyrophosphates, 296, 311 Pyrophosphoric acid, 312, 313 Pyrovanadates, 295 Pyroxylic spirit, 383 Pyroxylin, 360 Pyroxylon, 360 Quadrivalence, 47 594 INDEX Qualitative analysis, 84 Quantitative analysis, 404 et seq, Quantivalence, 47, 104 of atoms, definition of, 52 of acidulous radicals, 50 Quartz, 314 Quassice lignum, 343 Quassin, 343 Quercitrin, 415 Quercitron, 415 Quercus cortex, 317 tinctoria, 415 Queveiine’s iron, 135 Quicklime, 91 Qiiinice sulphas, 343 sulphas, impurities in, 546 valerianas, 344 Quinia, or quinine, 343 analytical reactions of, 344 citrate of iron and, 131 De Vry’s process for estimat- ing, 529 disulphate of, 344 kinate of, 343 quantitative estimation of, 528 sulphate of, 344 Quinia wine, 344 Quinicia, 346 Quinicine, 346 Quinidia, 346 Quinidine, 346 Quinine, citrate of, 344 Quinquivalence, 47 Radicals, acidulous, 55, 235 acidulous, formulae of, 55 alcohol-, 382 basylous, 104 definition of, 54 Racemic acid, 285 Raisins, 363 Rational formulae, 373 Reactions, analytical, 53 synthetical, 53 Reagents, list of, x. Real alcohol, 374 Realgar, 144 Reaumur’s thermometer, 448 Reciprocal proportions, law of, 42 Rectification, 109 Rectified oil of turpentine, 408 spirit, lOi), 373 Red chromate of potassium, 210 Red— coloring-matters, 415 corpuscles in blood, 437 earth, 415 enamel colors, 416 gravel, 432 haematite, 119 iodide of mercury, 173 litmus-paper, 83 lead, 187, 415 ochre, 415 oxide of iron, 129, 415 phosphorus, 259 -poppy petals, 415 precipitate, 178 prussiate of potash, 303 -rose petals, 415 sandal-wood, 415 Venetian, 129 Reduced indigo, 258 iron, 135 Reducing flame, 331 Reinsch’s test for arsenicum, 148 Relative weight of hydrogen and oxygen, 22 Rennet, 397 Reseda luteola, 415 Resin, 410 of arnica, 411 of cannabis, 411 of capsicum, 411 of castor, 411 of ergot, 411 of guaiacum, 369 of Indian hemp, 411 of jalap, 369 of kamala, 411 of kousso, 411 of mastic, 411 of mezereon, 411 of pepper, 353 of podophyllum, 351 of pyrethrum, 411 of rottlera, 411 of scammouy, 371 Resina, 410 jalapce, 369 podopliylli, 351 scammonice, 371 Resinoid substances, 410 Resins, 410 Respiratory materials of food, 398 Retort, 108 INDEX 595 Rhceados petala^ 415 Rhamni succusj 367, 416 Rhamnus catharticus^ 416 infectorius, 416 Rhaponticin, 300 Rbatanj root, 318 Rhei radix, 300 radix, impurities in* 300 Rlieic acid, 300 Rhein, 300 Rheumin, 300 Rhodium, 221 Rhubarb, oxalate of calcium from, 435 Rhubarbic acid, 300 Rhubarbarin, 300 Rhus cotinus, 414 Ricinoleate of glyceryl, 403 Ricinoleine, 403 Roccella, 416 Rochelle salt, 72, 286 Rock-salt, 67 Roll sulphur, 269 Roman cement, 314 Rosce canince fructus, 363 centifolice petala, 407 gallicce petala, 415 Roscoe’s vanadium, 295 Rosaniline, 417 Rose-oil, 407 -water, 405 Rosemary-oil, 408 Rosin, 410 Rottlera tinctorial 411 Rottlerin, 411 Rouge, animal, 300, 415 mineral, 129, 415 vegetable, 416 Rubia tinctorum^ 415 Rubian, 384 Rubidium, 552 Ruby, 116 Rue-oil, 408 Rumicin, 300 Rust of iron, 120 Rutate of glyceryl, 402 Ruthenium, 221, 552 Rutic acid, 402 aldehyd, 408 Sahadilla or sabadilline, 354 Sabince oleum, 408 • Saccharated carbonate of iron, 122 Saccharated^ carbonate of iron, volumetric estimation of, 492 Saccharic acid, 365 Saccharimetry, 534 Saccharine substances, 355, 361 Saccharometer, 535 Saccharum lactis, 362 purificatuin, 361 ustuin, 364 Safety-lamp, 21 Safflower, 415 Saffranin, 415 Saffron, 415 bastard, 415 dyer’s, 415 Safren, 408 Sago, 356 Sal-ammoniac, 76 Salicin, 370 Salicyl, hydride of, 370, 390 Salicylate of methyl, 390 Salicylous acid, 390 Saligenin, 370 Saliva, 438 Sal prunella, 253 Salt, common, 67 definition of a, 52 of sorrel, 282 Saltpetre, 253 Chili, 250 Salts, acid, 269 action of the blowpipe on, 331 action of heat on, 330 action of sulphuric acid on, 330 of ammonium, volatility of, 84 analogies, of, 73 analysis of insoluble, 328 constitution of, 54, 107, 235, 253, 267 formation of, 58 nomenclature of, 59, 63 of iron, nomenclature of, 120 physical properties of, 329 substitution of for each other, 73 table of the solubility or fn- solubility of, in water, 325 Sal volatile, 79 Sambucene, 408 Sambuci Jiores, 408 Sand, 314 -bath, 24 596 INDEX Sand — -tray, 24, 177 Sandstone, 314 Sanguinaria, 353 vinegar, 2(55 Santalin, 415 San ton lea, 370 Santonin, 370 Santoninum, 370 impurities in, 546 Santoniretin, 370 Sapan-wood, 415 Sap-green, 416 Sapo durus, 400 darns, impurities in, 546 mollis, 400 mollis, impurities in, 546 Saponin, 371 Sapphire, 116 Sarcince ventriculi, in urine, 439 Sarcolactic acid, 309 Sarsaparilla, 371 Sarzee radix, 371 Sassafras-oil, 408 Sassafras radix, 408 Sassafrol, 408 Saturated solutions, boiliug-points of, 450 Saturating power of citric acid, 290, 549 power of tartaric acid, 286, 549 Saturation, 57 tables, 286, 290, 549 Saturn, 186 Saturnine colic, 186 Savin-oil, 408 Saxon blue, 416 Saxony blue, 416 Scale compounds of iron, 186 Scammonice radix, 371 resina, 371 resina, impurities in, 547 Scammonin, 371 Scammoniol, 371 Scammonium, 371 Scammouy, resin of, 371 Scents, 406 Scheele’s green, 152 Schist, 116 Schonbein’s test for hydrocyanic acid, 251 Schweinfurth green, 152 Science of chemistry, 14 Scilla, 364 Scoparii cacumina, 353 Scoparin, 333 Sea-salt, 67 Sediments, urinary, 432 urinary, microscopic exami- nations of, 433 Seidlitz powder, 287 Selenium, 552 Senegee radix, 371 Senna alexandrina, 366 indica, 367 Sepia, 417 Serolin, 396 SerpentaricB radix, 355 Serpent’s excrement, 309 Sevum preeparatum, 402 Sexivalence, 47 Shale, 116 Sherry-wine, 372 Sienna, 417 Sifting, an aid to analysis, 330 Silica, 314 Silicate of aluminium, 116 calcium, 90, 314 magnesium, 314 Silicates, 314 quantitative estimation of, 524 tests for, 315 Silicic acid, 314 anhydride, 315 Siliciuretted hydrogen, 315 Silico-fluoride of barium, 89 Silicon, chloride of, 315 derivation of word, 30 fluoride of, 315 hydride of, 315 oxide of, 315 Silver, 191 amraonio-nitrate of, 153, 182 analytical reactions of, 193 antidojtes to nitrate of, 195 arseniate of, 153 arsenite of, 153 bromide of, 194 chloride of, 192 chromate of, 194 citrate of, 291 coinage, 191, 467 cyanide of, 194 by cupellation, estimation of, 513 derivation of word, 29 INDEX 59t Silver — extraction of, 191 German, 109 iodide of, 194 nitrate of, 191, 192 oxalate of, 283 oxide of, 193 phosphate of, 194 pure, 192 quantitative estimation of, 513 standard solution of nitrate of, 486 sulphide of, 191 sulphite of, 274 tartrate of, 288 tree, 194 volumetric estimation of, 513 Sinalbin, 393 Sinapis, 393 impurities in, 547 Siphon, vide Syphon. Size, 398 Slaked lime, 91 Slate, 116 Smalt, 207, 416 Smilacin, 371 Soap, ammonium, calcium, hard, potassium, sodium, soft, 400 Soap-stone, 417 -wort, 341 “Soda,” 279,482 Soda-alum, 116 -ash, 73, 482 caustic, 68 Soda, 68 caustica, 68 caustica, impurities in, 547 tartarata, 72 tartarata, impurities in, 547 Soda-lime, 527 powders, 73 solution of chlorinated, 72, 495 standard solution of, 483 valerianate of, 321 volumetric estimation of, 478 water, 71 Sodse, vide Sodii. Sodii acetas, 69 acetas, impurities in, 547 arsenias, 146 arsenias, impurities in, 547 hicarbonas, 69, 70 Sodii — bicarhonas, impurities in, 547 boras, 296 carbonas, 270 carbonas, impurities in, 547 carbonas, exsiccata, 70 chloratce, liquor, 72, 495 cliloridum, 67 citro-tartras effervescens, 73 hypophospkis, 306 hyposulphis, impurities in, 547 liquor, 68 nitras, 225 nitras, impurities in, 547 phosphas, 95 phosphas, impurities in, 547 sulphas, 239 sulphas, impurities in, 547 sulphis, 273 valerianas, 321 valerianas, impurities in, 547 Sodic carbonate, etc., vida salts of sodium. Sodio-citrate of iron, 130 -tartrate of iron, 130 Sodium, 67 acetate of, 69 acid carbonate of, 69, 478 acid sulphate of, 239 acid tartrate of, 66 analytical reactions of, 74 and aluminium, double chlo- ride of, 115 antimoniate of, 74 arseniate of, 146 arsenite of, 144 bicarbonate of, 69 bisulphite of, 270 bromate of, 73 bromide of, 73 carbonate of, 68, 73, 279,478 carbonate of, manufacture of, 73, 279 chlorate of, 73 chloride of, 67 citrate of, 73 derivation of word, 28 -flame, 74 hydrate of, 68 hypochlorite of, 72 hypophosphite of, 306 hyposulphite of, 306 iodate of, 73 iodide of, 73 598 INDEX. Sodium— maiiganate of, 73 nitrate of, 68, 252 other compounds of, 73 oxalate of, 282 permanganate of, 73 phosphate of, 95 phosphate of, how prepared from phosphate of calcium, 95 potassium and ammonium, separation of, 85 p^^roarseniate of, 146 quantitative estimation of, 478, 501 salts, analogy of, to potassium salts, 73 salts, sources of, 67 sulphate of, 239 sulphite of, 273 valerianate of, 321 Soft soap, 400 Soils, analysis of, 539 Solania, 353 Solanine, 353 Solarium dulcamara^ 353 Solder, 185,213 Solid, definition of, 49 fats, 400 potash, 56 Solids lighter than water, to take the specific gravity of, 468 to take the specific gravity of, 467 et seq. Solubility of carbonic acid gas in water, 71 of gases in liquids, 71 of precipitates in strong solu- tions of salts, 231, 250 or insolubility of salts in water. Table of, 325 Soluble cream of tartar, 297 glass, 315 substances, to take the spe- cific gravity of, 468 tartar, 297 Solution of acetate of ammo- nium, 78 acetate of potassium, 57 acetate of sodium, 69 albumen, 395 ammonia, 77 ammonio-nitrate of silver, 153, 182 Solution of — ammonio-sulphate of copper, 153, 182 ammonio-sulphate of magne- sium, 103, 522 arsenic in acid, 145 arsenic in alkali, 144 boracic acid, 296 bromine, 242 carbonate of ammonium, 79 chloride of ammonium, 76 chloride of antimony, 155 chloride of barium, 87 ’chloride of calcium, 90 chloride of calcium, saturat- ed, 90 chloride of gold, 217 chloride of tin, 214 chloride of zinc, 112 chlorinated lime, 97, 495 chlorinated soda, 72, 495 chlorine, 24, 25 citrate of ammonium, 79 citrate of magnesium, 101 ferridcyanide of potassi urn, 304 ferrocyanide of potassium, 302 gelatine, 398 iodate of potassium, 62, 263 iodide of potassium, 62 iodine, 244 lime, 92 litmus, 83 nitrate of mercury, 174 oxalate of ammonium, 80 perchloride of iron, 126, 127 perchloride of mercury, 177 perchloride of platinum, 219 pernitrate of iron, 135 persulphate of iron, 127 phosphate of sodium, 96 phosphoric acid, 293 potash, 53, 55 red prussiate of potash, 304 soda, 68 strychnia, 348 subacetate of lead, 186 sulphate of calcium, 97 sulphate of indigo, 258 sulphate of iron, 121 sulphide of ammonium, 80 sulphydrate of ammonium, 80 tartaric acid, 285 INDEX. 599 Solution of — yellow prussiate of potash, 302 Sonnenschien’s process for poison- ous alkaloids, 426 Soot, 26 Source of heat, 16 Sovereign, weight of the, 217 Spar, fluor-, 304 heavy, 87 Sparteiaor sparteine, 35 3 Spathic iron-ore, 119 Spearmint oil, 407 Specific gravity, 463 gravity of gases, 469 gravity of liquids, 464 gravity of official liquids, 464 gravity of oxygen, 22 gravity of powders, 467 gravity of solids, 467 gravity of solids lighter than water, 468 gravity of soluble substances, 468 weight, 463 Spectrum analysis, 336 Specular iron-ore, 119 Speculum metal, 213 Speiss, 208 Spermaceti, 402,451 Spermatozoa, in urine, 439 Sperm-oil, 402 Spircea ulmaria, 370 Spirit of French wine, 376 methylated, 383 myrcia, 372 of nitrous ether, 312, 379 of nitrous ether, adulterated, 384 proof, 373 pyroxylic, 383 rectified, 373 of turpentine, 408 of wine, 373 of wine, impurities in, 487 wood-, 383 Spirits, 442 analysis of, 536 Spiritus cBtheris, 378 cetheris nltrosi, 379 cetheris nitrosi^ impurities in, 547 ammonice, 79 ammonice aromaticuSy 79 Spiritus — ammonice, aromaticuSy impuri- ties in, 547 ammonice fcetiduSy 79 anisiy 406 cajuputi, 405 cinnamomiy 406 chloroj'ormi, impurities in, 547 frumentiy 372 juniperiy 405 lavandulcCy 405 menthce piperitce, 406 myrciccy 372 myristiccBy 405 rectiJicatuSy 448, 473 rectificatuSy impurities in, 547 rosmariniy 405 tenutoVy 373 tenuior, impurities in, 547 vini gallici, 376 Spodumene, 201 Spongy platinum, 221 Spruce fir, 411 Spurge laurel, 411 i'Squill, 364 Standard gold, 217 Standard solution of hyposul- phite of sodium, 493 solution of iodine, 488 solution of nitrate of silver, 486 solution of oxalic acid, 477 solution of red chromate of potassium, 491 solution of soda, 483 solution of sulphuric acid, 482 Stannate of sodium, 215 Stannates, 215 Stannic acid, 215 anhydride, 215 chloride, 214 oxide, 215 sulphide, 216 anhydrous, 21 6 Stannous chloride, solid, 214 hydrate, 216 oxide, 21 6 sulphide, 215 Stannumy 30 Star-anise oil, 406 Starch, 355 blue, 356 quantitative estimation of, 534 -sugar, 363 • 600 INDEX Stas’s process for poisonous alka- loids, 425 Steam-bath, 500 Stearic acid, 400, 404 Steariiie, 400 Stearoptens, 405 Steatite, 417 Steel, 119 wine, 133 Stibium^ 29 Still, 108 Stoddart’s test for quinine, 345 Stone-coal, 213 red, 415 Storax, 413 Strarnonii folia^ 350 sfmina^ 350 Stream-tin, 213 Strontianite, 202 Strontium, 202 analytical reations of, 202 carbonate of, 202 derivation of word, 30 flame, 202 nitrate of, 202 sulphate of, 202 Structure of flame, 21 Strychnia^ 347 Strychnice sulphas, 347 Strychnia or strychnine, 347 or strychnine, impurities in, 547 analytical reactions of,347,423 in organic mixtures, detection of, 423 Strychnos Ignatius, 347 Strychnos nux vomica, 347 Styracin, 413 Styrax benzoin, 413 prceparalus, 413 Styrol, 413 Styrone, 413 Subacetate of copper, 168 of lead, 186 Subcarbonate of iron, 122 Subchloride of mercury, 177 Sublimation, 78, 176 Sublimed sulphur, 269 Subnitrate of bismuth, 223 Substances readily deoxidized, quantitative estimation of, 493 readily oxidized, quantitative estimation of, 488 Substitution-products, 386 Succi, 442 Succinic acid, 315 Succinum, 315 Succus limonum, 290 Sucrose, 361 Suet, 402 prepared, 402 Sugar, 361 brown, 361 -candy, 361 cane-, 361 detection of in urine, 430 grape-, 362 inverted, 361, 362 lump, 361 -maple, 361 milk-, 363 moist, 362 of lead, 186 quantitative estimation of, 534 tests for, 361 Sulphate of aluminium, 116 aluminium and ammonium, 116 ammonium, 76 ammonium and iron, 117 barium, 88 bismuth, 225 cadmium, 222 calcium, 90, 97 chromium, 211 cinchonia, 346 cobalt, 207 copper, 168 copper, anhydrous, 168 cupr-diammon-diammonium, 182 indigo, 258 iron, 121 iron, solution of, 121 lead, 89 magnesium, 100, 505 manganese, 206 mercury, 175 potassium, 60, 255 quinine, 343 sodium, 239 strontium, 202 zinc, 110 Sulphates, 275 analytical reactions of, 277 quantitative estimation oC 519 INDEX. 601 Sulpliethylic acid, 377 Sulphide of ammonium, 80 antimony, 155, 157 arsenicum, 151 arsenicum, native, 144 barium, 88 bismuth, 266 cadmium, 222 calcium, 279 cobalt, 207 copper, 168 iron, 121 lead, 189 lead, native, 185 manganese, 206 mercury, 182 mercury, native, 170 nickel, 209 potassium, 56 silver, 194 silver, native, 191 tin, 215 zinc, 114 zinc, native, 110 Sulphides, 269 analytical reactions of, 271 arsenicum, native, 144 quantitative estimation of, 517 Sulphindigotic acid, 258 Sulphindylic acid, 258 Sulphite of barium, 274 calcium, 274 magnesium, 273 potassium, 273 silver, 274 zinc, 109 Sulphites, 272 analytical reactions of, 274 quantitative estimation of, 519 Sulphocarbolates, 392 Sulphocarbolic acid, 392 Sulphocyanate of allyl, 393 butyl, 382 iron, 138 Sulphocyanates, 316 Sulphocyanic acid, 316 Sulphocyanides, 816 Sulphocyanogen, 316 Sulphophenates, 392 Sulphophenic acid, 392 Sulphovinic acid, 377 Sulphur, 26 51 Sulphur — adulteration of, 271 allotropy of, 359 analytical reactions of, 271 arsenic in, 152 bromide of, 272 chloride of, 272 derivation of word, 28 estimation of, 517 flowers of, 269 hypochloride of, 272 iodide of, 244 liver of, 58 milk of, 270 oxyacids, 307 plastic, 269 precipitated, 270 roll, 269 sublimed, 269 Sulphur loturriy 269 prcecipitatum, 270 prcecipitaturrij impurities in, 547 subliinatum, 269 sublimatum, impurities in, 547 Sulphurated antimony, 159 potash, 56 Sulpliurets, vide Sulphides. Sulphuretted hydrogen, 269 Sulphuric acid, 275 acid, antidotes to, 278 acid, aromatic, 276 acid, dilute, 276 acid, fuming, 277 acid, Nordhausen, 277 acid in organic mixtures, de- tection of, 421 acid, purification of, 277 acid, standard solution of, 482 acid, volumetric estimation of, 484 anhydride, 276 Sulphuris iodidum, 214 iodidum, impurities in, 548 Sulphurous acid, 26, 272 acid, volumetric estimation of, 489 anhydride, 272 Sulphydrate of ammonium, solu- tion of, 81 Sulphydric acid, 81, 269 Sumatra camphor, 409 Sumbul, 412 1 Superphosphate of lime, 292 602 INDEX Supporters of combustion, 21 Suppositoria acidi tanici^ 317 morphice^ 341 pUiinhi compositaj 186 Suppositories, 442 Surface unit, 455 Surgery, 14 Sweet spirit of nitre, 312, 379 spirit of nitre, adulterated, 384 Sylvie acid, 410 S.vmbol, function of, 37 Symbols of elements, 27, 37 illustrative of chemical action by, 40 Sympathetic inks, 208 Synaptase, 366 Synthesis, 52 Syphon, 94 Syrup of iodide of iron, 27 Syrups, 442 Syrupi, impurities in, 548 Syrupus aurantii, 406 aurantii Jloris, 406 ferri iodidi, 27 ferri phosphatisj 123 fuscus, 364 Tahaci folia, 352 Tamarindus, 289 impurities in, 543 Tannic acid, 317 Tanning, 318 Tantalum, 552 Tapioca, 356 Taraxaci radix, 343 Taraxacin, 243 Tartar, meaning of, 284 Tartar, cream of, 53, 66, 284, 478 emetic, 157, 284 emetic, estimation of anti- mony in, 509 Tartarated antimony, 157 Tartaric acid, 284, 315 saturating power of, 286, 549 solution of, 385 Tartarus boraxatus, 397 Tartrate of ammonium, 84 antimony and potassium, 157, 284 calcium, 287 potassium, acid, 53, 66 potassium, neutral, 66 potassium and sodium, 72 Tartrate of — silver, 288 sodium, 66 Tartrates, 61, 284 analytical reactions of, 287 volumetric estimation of, 485 Taurine, 401 Taurocholates, 401 Tellurium, 552 Temperature, correction of vol. of gas for, 469 measurement of, 447 Terehinthina, 408 canadensis, 408 Terra di sienna, 417 Terra jap onica, 318 Testa preeparata, 94 Test-papers, 83 -tube, 16 Tetramines, 339 Tetrathionic acid, 307 Tetryl, 381 Thalleiochin, 344 Thallium, 552 Thebaia, 341 Theia, 353 Theine, 353 Thenard’s blue, 416 Theobroraa oil, 402 Therapeutics, definition and deri- vation of, 14 Theriaca, 364 Thermometer, 447 Celsius’s, 448 Centigrade, 448 Fahrenheit’s, 448 Reaumur’s, 448 Thermometric scales, conversion of degrees of, 449 Thionic acids, 307 Thorinum, 552 Thorium, 552 Thorn-apple, 350 Thus americanum, 412 Thyme, oil of, 409 Thymene, 409 Thymol, 409 Tiglic acid, 403 Tin, 213 amalgam, 214 analytical reactions of, 215 antidotes to, 216 block, 213 chloride of, 214 INDEX. 603 Tin- derivation of word, 30 dropped or grain, 213 foil, 214 granulated, 214 oxide of, 215 perchloride of, 214 plate, 214 prepare-liquor, 215 -stone, 213 tacks, 214 -white cobalt, 207 Tinctura ferri acetatis, 127 ferri perchloridi^ 126 iodi, 244 iodinii^ 244 iodinii composita^ 244 quinioe^ 344 Tincturm, 126 Tinctures, 126, 442 Tinnevelly senna, 367 Titanium, 552 Tobacco, 353 Tolu, balsam of, 413 Toluol, 391 Tons les mois, 357 Toxicology, 418 Tragacantb, 97 Tragacantha, 97 Treacle, 366 Triads, 165 Triamines, 339 Triangle, wire, 84 Tribasic acids, 237 Trybasylous radicals, 237 Triethylamine, 339 Triethylia, 339 Trinitro-carbolic acid, 392 Trinitrocellulin, 359 Tripbane, 201 Trithionic acid, 307 Trityl, 381 Tritylia, 339 Trivalence, 47 Trivalent radicals, 47, 55, 104 Trochisci acidi tannici^ 317 bismuthi, 224 fei’ri redacti, 135 morphicB, 341 morpliicB et ipecacuanhce, 341 potassce chloraiis, 262 sodce bicarbonatiSf 71 Tube-funnels, 81 Tubes for collecting gases, 61 Tubes — glass, Glass tubes. Tungsten, 552 Turgite, 129 Turmeric, 415 Turmeric paper, 83, 297 Turnbull’s blue, 304, 416 Turpentine, 408 American, 408 Bordeaux, 408 Canadian, 408 Chian, 408 French, 408 rectified oil of, 408 spirit of, 408 Venice, 408 Turpetb mineral, 176 Turps, 408 Type-metal, 155, 185 Ulmi cortex^ 318 Uhnus fulva, 318 Ultimate analysis, 525 Ultramarine blue, 416 green, 416 Umber, 417 Unguentum aconitice, 349 antimonii tartarati^ 157 atropice^ 350 cadmii iodidi^ 221 cerusscBf 186 hydrargyria 171 hydrargyri ammoniati, 182 hydrargyri iodidi rubric 174 hydrargyri nitratis, 175 hydrargyri oxidi rubri, 179 hydrargyri subchloridi, 178 iodi, 244 iodinii compositum^ 244 pJumbi acefatis, 187 plumbi carbonatis, 186 plumbi iodidi, 188 plumbi subacetatis compositum^ 187 sulphuris iodidi, 244 veratrice, 354 zinci, 112 Units of capacity, 455 surface, 455 weight, 455 Univalence, 47 Univalent radicals, 47, 55, 104 Uranium, 552 Urate of lithium, 201 604 INDEX. Urates, 320 UrceoJa elastica^ 493 Urea, 301, 430 artificial, 301,431 Uric acid, 320, 434 Urinary calculi, 439 calculi, examination of, 439 deposits or sediments, plates of, vide 434 et seq, sediments, 432 sediments, microscopical ex- amination of, 433 Urine, 429 diabetic, 362, 430, 534 morbid, examination of, 429 Urinometer, 466 Uvce, 363 ursi folia, 310 Valerian oil, 408 Valeriance radix, 408 Valerianate of amyl, 389 of quinia, 344 sodium, 321 zinc, 113, 321 Valerianates, 320 Valerianic acid, 320, 404 Valerol, 408 Vanadates, 296 Vanadinite, 296 Vanadium, 296, 552 relationship to nitrogen, phos- phorus, and arsenicum, 296 Vanilla, 413 Vapor acidi hydrocyanici, 249 chlori, 25 conice, 352 iodi, 243 Vapor-density, 470 Variolaria, 416 Vegetable albumen, 298 and animal life, relation of, 7 casein, 356, 398 crocus, 415 fibrin, 356, 398 gelatine, 358 green, 416 jelly, 358 oil, 400 rouge, 416 substances, 338 et seq, Venetian red, 129 Venice turpentine, 408 } 'eratri viridis radix, 354 Veratria, 354 impurities in, 548 Veratria or Veratrine, 354 Veratrum album, 354 Verdigris, 168 Vermilion, 182 Vinegar, 265 of cantharides, 265 squill, 265 Vinuin antimonale, 157 aurantii, 372 ferri, 133 ferri citratU, 133 poi'tense, 372 quinice, 344 xericum, 372 Vitriol, blue, 121 green, 121 oil of, 276 white, 121 Volatile oils, vide Oils. Volatility of salts of ammonium, 84 Volatilization, 84 Volcanic ammonia, 76 Volume, combination by, 44 of gas, corrections of, 469 molecular, 46 Volumetric analysis, 475 estimation of acetate of lead, 480 estimation of acetic acid, 484 estimation of acids, 483 estimation of alkalies, 476 estimation of alkaline carbo- nates, 481 estimation of ammonia solu- tions, 478 estimation of arseniate of iron, 492 estimation of arseniate of so- dium, 487 estimation of arsenic and arsenical solutions, 489 estimation of borax, 480 estimation of bromides, 487 estimation of bromide of po- tassium, 487 estimation of chlorides, 515 estimation lime, 495 of chlorinated estimation soda, 494 of chlorinated estimation of chlorine, 495 INDEX. 605 Volumetric — estimation of citrate of potas- sium, 481 estimation of citrates, 481 estimation of cyanides, 487 estimation of hydrochloric acid, 484 estimation of hydrocyanic acid, 487 estimation of hyposulphite of sodium, 489 estimation of iodides, 487 estimation of magnetic oxide of iron, 492 estimation of nitric acid, 484 estimation of official com- pounds, 478, 484, 486, 489, 492, 494 estimation of phosphate of iron, 492 estimation of potash, 478 estimation of saccharated car- bonate of iron, 492 estimation of soda, 478 estimation of sugar, 534 estimation of sulphides, 517 estimation of sulphites, 519 estimation of sulphuric acid, 484 estimation of sulphurous acid, 489 estimation of tartrates, 481 solutions, 477, 482, 4b3, 486, 488, 491,493 Vulcanite, 414 Vulcanized India-rubber, 414 Washing-bottles, 93, 498 precipitates, 93, 499 Warmth of animals, how kept up, 18 Water, 108 aerated, 71 -bath, 500 boiling-point of, 450 chalybeate, 119 composition of, 20 crystallization, 70 quantitative estimation of, 524 cubic inches of, in a gallon, 469 distilled, 109 evaporation of, 58 Water — formation of, expressed by symbols, 39 hardness of, 281 lime-, 92 of crystallization, 70, 71 -oven, 498 oxygenated, 88 purification of, 108, 281 softness of, 281 weight of 1 cubic inch of, 470 weight of minim, drachm, ounce, pint, and gallon, 460 Wax, 402 Weighing-tubes, 498 Weight, 452 estimation of, 452 molecular, 46 of air, 470 of hydrogen, 470 of water, 470 specific, 463 Weights, atomic, 43 and measures of the British Pharmacopoeia of 1867, 459 and measures of the metric decimal system, 454 et seq, balance, 453 relation of metrical to the weights of the U. S. Phar- macopoeia, 458, 459 relative, 44 Weld, 415 Welding, 221 Wheaten fiour, 355 Whey, 362, 397 Whiskey, 372 White arsenic, 144 indigo, 258 lead, 186 pepper, 353 pigments, 417 precipitate, fusible, 181 infusible, 182 resin, 410 vitriol, 121 wax, 402, 457 Whiting, 94 Willow bark, 370 Wine, 372, 493 antimonial, 157 iron, 133 orange, 372 quinine, 341 606 INDEX. Wine — sherry, 372 steel, 133 Winter-green, oil of, 390 Wire-gauze tray, 24 triangle, 84 Witherite, 87 Wood-charcoal, 95 creasote, 391 naphtha, 383 oil, 412 spirit, 383 tar, 412 Woody nightshade, 353 Wormseed, 408 Wrought iron, 120 Xanthin, 441 Xylol, 391 Yard, 460 Yeast, 372 Yelk of egg, 396 Yellow chromate of potassium, 210 coloring-matters, 414 ochre, 414 oxide of mercury, 179 prussiate of potassium, 248, 302 sienna, 414 wax, 402, 457 wood, 414 Yolk of egg, 396 Yttrium, 552 Zaflfre, 207 Zinc, 109 acetate of, 112 analytical reactions of, 114 Zinc — antidotes to, 115 carbonate of, 109, 112 chloride of. 111 derivation of word, 29 detection of in presence of aluminium and iron, 139 -ethyl, 380 ferrocyanide of, 114 granulated, 19 hydrate of, 114 in organic mixtures, detection of, 421 oxide of, 113 oxide of, Hubbuck’s, 113 quantitative estimation of, 506 sulphate of, 110 sulphide of, 114 sulphide of, native, 109 sulphite of, 114 valerianate of, 113 wliite, 113 Zinci acetaSy 113 acetas, impurities in, 548 carbonas, 109, 112 carbonasy impurities in, 548 chloridiy liquor y 112 chloridurriy 111 chloriduMy impurities in, 548 oxiduniy 113 oxiduMy impurities in, 548 sulphasy 110 sulphasy impurities in, 548 unguentuMy 112 valerianasy 113, 321 valerianasy impurities in, 548 Zincuiriy 110 granulaturRy 19 Zingiber y 408 ^ Zirconium, 552 I Call Number Overdue books are subject to a fine of 2 cents a day. N am Univ. of 111. Lib. Call Slip