rcooiiuuiua [lMI||l!j||llHf!ilM «iP!Hj»ijffi»IJH«iyM mmwi tftfTltUT iii fill. iiiiu LIBRARY OF CONGRESS. Shelf. ..Tb'^ 3 UNITED STATES OF AMERICA. AN ELEMENTAEY COURSE IN INORGAMO PHARMACEUTICAL AND MEDICAL CHEMISTRY. DESIGNED ESPECIALLY FOR STUDENTS OF PHARMACY AND MEDICINE. y FREDERICK J. WULLING, Bean, and Professor of the Practice and Theory of Pharmacy, and of Pharmor ceutical Chemistry at the College of Pharmacy of the University of Minnesota : late Professor of Inorganic Pharmaco- Diagnosis at the Brooklyn College of Pharmacy ; formerly Iiistruc- tor of Pharmacy at the College of Pharmacy of the City of New York : Author of " The Evolution of Botany,''' etc. Kevised, and reprinted prom the Pharmaceutical Record. NOV 2C1BS4 FIRST EDIT! FIRST THOUSAND. "> ^ ' ' ^ """^ 5 2/;^ NEW YORK : JOHN WILEY & SONS, 53 East Tenth Street. 1894. Copyright, 1894, BY Frederick J. Wulling. ROBERT DRUMMOND, ELECTROTYPER AND PRINTER, NEW YORK. PEEFACE. The Elementary Course in Pharmaceutical and Medical Chemistry was first published in the Pharmaceutical Record during the year 1892. Its original purpose was to direct and guide those pharmaceutical and medical students who had not the advantages of the personal direction of a teacher in their chemical studies. The course admirably carried out this purpose with its early readers, and its pub- lication in book-form is in response to requests from many of these readers, and from teachers of chemistry. It was the author's intention to thoroughly revise the course, to eliminate much and to add more; but the many duties in- cumbent on a busy life havo not permitted more than a partial revision. The method of presentation is the result of the author's experience as a teacher of pharmaceutical chemistry. The work is presented in such form that no part of it is complete without the other; it is necessary to study the book from beginning to end to follow its logical sequence. Kepetition is adopted purposely; the statements which are repeated, perhaps frequently, are those which beginners do not always grasp the first time they are made. Eepetition in an elementary course such as this is essential; it has the advantage which lies in the presentation of the same facts in so many different forms lit IV PREFACE. of language that the reader will find at least one form un- derstandable. In a few instances where it seemed well, the language of others is quoted to make clearer the point under discussion. Facts in chemical philosophy are scattered through the book and are given where they seemed to fit best and where their application is most appropriate. The course is graded in a manner which requires that it be studied page by page. Its plan is to gradually lead up to the comprehension of the chemistry of the inorganic salts official in the United States Pharma- copoeia. The explicitness and detail of the treatment of the subjects up to the metals and their salts render brevity thereafter possible, in that the study of the salts requires essentially only the application of the principles laid down in the first half of the course. Where repetition is useless it is not employed ; so it has been possible, to an extent, to study the properties of salts of the same metal collect- ively. The author is gratefully appreciative of the aid rendered by those who have favored him with valuable suggestions, and to those who have so kindly assisted in reading and correcting the proof. He desires also to express his gratitude for the favor with which the course was received during its first publica- tion, and he indulges the hope that in its present form it will be still more worthy of the confidence of pharmaceuti- cal and medical students and teachers. Minnesota State University, Minneapolis, Nov. 1894. CONTENTS. PAGE A Course in Elementary Inorganic Pharmaceutical AND Medical Chemistry 1 Introductory 2-20 Molecular Forces, Atomic Force, The Elements, Non- Metals, Metals, Physical Properties of the Elements, Chem- ical Properties of the Elements, Atomic Weights, Law of Definite Chemical Proportion, Quantivalence Table of Elements, Quantivalence, Symbols and Atomic Weights ; Chemical Notation. NON-METALS. Oxygen 21-28 History, Occurrence in Nature, Preparation, Physical Properties, Chemical Properties, Uses and Compounds in Pharmacy and Medicine, Ozone, Tests and Experiments. Hydrogen 28-34 History, Occurrence in Nature, Source, Preparation, Phys- ical Properties, Chemical Properties, Tests and Experi- ments, Uses in Pharmacy, Compounds. Watsr 34-48 Composition, General Properties, Chemical Properties, Natural Waters, Atmospheric, Terrestrial, Hard Waters, Mineral Waters, Well-Waters, Purification of Water, Per- oxide of Hydrogen. Nitrogen 48-51 History, Occurrence in Nature, Functions in Nature, Properties, Preparation, Compounds, Tests for Nitrates. V VI CON"TENTS. PAGE Oxygen and Nitrogen as the Atmosphere 51-56 Chemical Constituents of the Air. Carbon 56-66 Occurrence in Nature, Properties, Compounds of Carbon with Hydrogen, Illuminating Gas, Compounds of Carbon with Hydrogen and Oxygen, Alkaloids and Glucosides, Compounds with Oxygen, Carbon with the Halogens, Car- bon with Nitrogen, Carbon with Sulphur. The Halogens. cht.orine 66-80 History, Occurrence in Nature, Preparation, Properties, Compounds Containing Chlorine, A Lesson in Nomenclat- ure, Experiments, Diffusion of Gases, Bleaching Properties, Disinfecting and DeodorizingProperties, Affinity of Chlorine for Hydrogen, Affinity of Chlorine for Bases, Solvent Power of Chlorine, Tests of Identity of Chlorine as Chloride, Chlo- rine in Pharmacy, Calx Chlorata, Liquor Sodae Chloratse. Iodine 80-85 Occurrence in Nature, Source, Preparation, Purification, Detection of Impurities, Properties, Compounds, Pharma- ceutical Preparations, Tests for Iodine and Iodides, Bromine 85-86 Occurrence in Nature, Preparation, Properties, Com- pounds, Tests. Fluorine 86 Sulphur 87-96 Occurrence in Nature, Preparation, Properties, Official Sulphurs, The Writing of Salts. Phosphorus 96-107 Occurrence in Nature, Source, Preparation, Properties, Experiments, Uses, Phosphorus in Pharmacy and Medicine. Boron 107-114 Occurrence in Nature, Preparation, Boric Acid, Tests for Purity of Boric Acid, Uses of Boric Acid, Borax. CONTENTS. Vll INORGANIC ACIDS. PAGE The Study of Acids and Salts, Antidotes to Mineral Acids, Medical Properties of the Acids 115-125 Sulphuric Acid 125-133 Preparation, Tests for Impurities, Uses, Dilute Sulphuric Acid, Aromatic Sulphuric Acid, Solid Sulphuric Acid. Sulphurous Acid 132-133 Preparation, Properties. Nitric Acid 134-139 Preparation (Functions and Uses of Equations), Prop- erties, Impurities, Uses in Pharmacy and Medicine, Dilute Nitric Acid. Hydrochloric Acid, 139-144 Preparation, Uses, Antidote, Dilute Hydrochloric Acid. NiTROHYDROCHLORIC ACID 144-145 Dilute Nitrohydrochloric Acid. Dilute Hydrobromic Acid 145-147 Preparation, Tests, Impurities, Uses. Hydriodic Acid 148-149 Preparation, Properties, Uses. Phosphoric Acid 149-156 Preparation, Varieties, Properties, Impurities, Tests, Dilute Phosphoric Acid, Glacial Phosphoric Acid, Phos- phorous Acid. Arsenous Acid 156-158 Preparation, Poisonous Properties, Antidote, Uses. Chromic Acid 158-159 Properties, Uses. THE METALS. Physical Properties, Chemical Properties, Unions with the Halogens, Haloid Salts, Normal, Acid, and Double Salts, Basic Salts or Oxy-salts, Kinds of Formula 159-172 The Alkalies. Properties, Alums 172-177 Vlll CONTENTS. PAGE Potassium Salts and Preparations 177-190 Sources, Tests, Impurities, Carbonate, Bicarbonate, Sul- phite, Acetate, Citrate, Solution of the Citrate, Mixture of the Citrate, Effervescent Citrate, Solution of the Arsenite, Sulphurated Potassa, Hypophosphite, Potassa, Potassa by- Alcohol, Potassa with Lime, Solution of Potassa, Perman- ganate, Iodide, Bromide, Ferrocyanide, Cyanide, Bichro- mate, Chlorate, Troches of the Chlorate, Bitartrate, Tartrate, Potassium and Sodium Tartrate, Nitrate, Sulphate. Sodium Salts and Preparations 190-irS Sources, Carbonate, Dried Carbonate, Bicarbonate, Com- mercial Bicarbonate, Soda, Solution of Soda, Arsenate, Bi- sulphite, Sulphite, Bromide, Chloride, Hypophosphite, Iodide, Phosphate, Pyrophosphate, Acetate, Benzoate, Salicylate, Sulphocarbolate, Borate, Nitrate, Sulphate, ■ Chlorate, Hyposulphite, Solution of Chlorinated Soda, Solution of the Arsenate, Solution of the Silicate, Troches of the Bicarbonate, Rhubarb and Soda Mixture. Ammonium Salts and Preparation 199-205 Tests, Sources, Chloride, Ammonia-Water, Stronger Ammonia- Water, Ammonia Liniment, Ammonia Spirit, Aromatic Spirit, Carbonate, Solution of the Acetate, Benzoate, Bromide, Nitrate, Valerianate, Iodide. Lithium Salts 205-207 Carbonate, Benzoate, Bromide, Citrate, Salicylate. Metals of the Alkaline Earths. Calcium Salts and Preparations 207-213 Sources, Prepared Chalk, Precipitated Carbonate, Troches of Chalk, Chloride, Bromide, Lime, Lime Water, Syrup of Lime, Lime Liniment, Sulphurated Lime, Chlorinated Lime, Labarraque's Solution, Hypophosphite, Precipitated Phos- phate. Strontium Salts 213-216 Properties, Tests for Identity and Purity, Bromide, Iodide, Lactate. Barium 216 CONTENTS. IX Magnesium Group. PAGE Magnesium Salts and Preparations 216-320 Tests, Sulphate, Carbonate, Magnesia, Heavy Magnesia, Solution of the Citrate, Effervescent Citrate, Sulphite. Zinc Salts and Preparations 220-224 Analytical Keactions, Sulphate, Impurities, Bromide, Valerianate, Precipitated Carbonate, Oxide, Ointment of the Oxide, Acetate, Solution of the Chloride, Chloride, Phosphide. Aluminum Salts 224-226 Analytical Keactions, Alum, Dried Alum, Hydrate, Sul- phate. Cerium 226 Oxalate. Lead Salts and Preparations , 226-232 Analytical Reactions, Oxide, Acetate, Solution of Subace- tate. Liniment of the Subacetate, Cerate of the Subacetate, Lead-Plaster, Diachylon Ointment, Nitrate, Iodide, Oint- ment of the Iodide, Carbonate, Ointment of the Carbonate. Copper Group. Copper Salts „ . .232-233 Analytical Reactions, Sulphate, Acetate. Mercury and Its Salts and Preparations 233-244 Important Reactions, Mass of Mercury, Mercurial Oint- ment, Mercurial Plaster, Ammoniac Plaster with Mercury, Mercury with Chalk, Mercuric Chloride, Mercurous Chloride, Ammoniated Mercury, Red Iodide, Yellow Iodide, Yellow Oxide, Ointment of Yellow Oxide, Oxalate, Red Oxide, Oint- ment Red Oxide, Cyanide, Ointment Ammoniated Mercury, Yellow Sulphate, Red Sulphide, Solution of Nitrate, Citrine Ointment. Silver Salts 244-247 Analytical Reactions, Nitrate, Fused Nitrate, Diluted Nitrate, Cyanide, Oxide, Iodide. Iron Group. Iron Salts and Preparations 247-269 X CONTENTS. PAGE Sources, Saccharated Iodide, Syrup of Ferrous Iodide, Ferrous Lactate, Ferric Chloride, Solution Ferric Chloride, Tincture Ferric Chloride, Solution Iron and Ammonium Acetate, Ferrous Sulphate, Granulated Ferrous Sulphate, Dried Ferrous Sulphate, Pills Aloes and Iron, Saccharated Ferrous Carbonate, Mass of Ferrous Carbonate, Reduced Iron, Pills of Ferrous Iodide, Compound Iron Mixture, Pills of Carbonate, Ferric Hypophosphite, Solution of Ferric Subsulphate, Solution of Ferric Sulphate, Ferric Ammonium Sulphate, Ferric Valerianate, Ferric Hydrate with Magnesia, Ferric Hydrate, Troches of Iron, Iron-Plaster, Solution of Ferric Acetate, Tincture of Ferric Acetate, Solution of Ferric Nitrate, Scale Salts, Soluble Ferric Phosphate, Syrup of the Phosphates of Iron, Quinine and Strychnine ; Soluble Ferric Pyrophosphate, Ferric Citrate, Iron and Ammonium Citrate, Wine of Ferric Citrate, Iron and Strychnine Citrate, Soluble Iron and Quinine Citrate. Manganese Salts 269-270 Dioxide, Sulphate. Metalloides. Aksenic Salts and Peepabations 270-278 Occurrence, Preparation, Properties, Physical and Chemi- cal; Analytical Reactions, Solution Arsenous Acid, Solution Potassium Arsenite, Iodide, Solution of Arsenic and Mer- curic Iodide, Sodium Arsenate, Solution of Sodium Arsenate, Paris Green. Antimony Salts and Prepabations 278-28H Occurrence, Preparation, Properties, Reactions, Sulphide, Purified Sulphide, Sulphurated Antimony, Compound Pills of Antimony, Oxide, Antimonial Powder, Antimony and Potassium Tartrate, Wine of Antimony. Bismuth Salts 283-286 Occurrence, Reactions, Subnitrate, Subcarbonate, Citrate, Bismuth and Ammonium Citrate. A Course in Elementary Inorganic Pharmaceutical and Medical Chemistry. INTEODUOTORY. Studeii^'ts in any branch of chemistry must all begin at the same starting-point. They must necessarily first ac- quire the knowledge of the fundaments, the elements of the science^ upon which, when once their own, they can construct or build any division of the science. So the student in pharmaceutical chemistry must first acquaint himself with the principles of chemistry without reference to the application of chemistry to pharmacy. When he has accomplished that, the principles may then be applied to pharmacy. Molecular Forces. — In order to intelligently understand the subject it will be necessary to deviate a little and enter the field of physics, to get enough knowledge from that to better comprehend the meaning of chemistry. The universe, the sum of all created things, is made up of what is termed matter, which material assumes three different forms, the solid, liquid, and gaseous. All things are in one of these three conditions, and the condition in which any given portion of matter exists is dependent upon the predominance of one or more of the natural forces. A given mass of matter is made up of little parti- cles which are held together by the force called cohesion — that is, the particles of matter through the agency of thia 2 PHARMACEUTICAL AND MEDICAL CHEMISTRY. force of attraction are made to unite to form a mass. If this force of cohesion is very strong, we have bodies which are very hard; is this force less strong, the bodies are soft or liquid. When this attractive force is altogether absent, and is replaced by another force having just the contrary- tendencies — that is, to repel the particles from each other — we have gases as a result. This latter force is called repulsion. It must be remembered that these forces act only on and between the small particles mentioned, which we will henceforth call molecules. A molecule is therefore the smallest particle of any kind of matter which will retain the characteristics or nature of the mass or body of which it is a part, and on and between which particles the forces of attraction and repulsion act. The latter two forces are often spoken of as molecular forces, because they concern themselves exclusively with molecules. The science which concerns itself with the molecular forces is termed physics or natural philosophy. Physics in a limited sense studies the nature of, and the phenomena observed in, bodies in which there is no change in composition or construction. Chemistry, on the other hand, comprehends only the internal structure, as it were, of the molecules. When we subdivide a given mass or body physically until it becomes impossible to further subdivide it without affect- ing its construction or internal structure, we arrive at what we call a molecule, and at this point we have reached the limit of physics, the sharp line which separates physics from chemistry. It is not impossible to further subdivide the molecule, but when we do so we destroy its internal structure and enter thereby the realm of chemistry. The molecule may be decomposed, resolved, into still smaller PHARMACEUTICAL AND MEDICAL CHEMISTRY. 6 particles, to which we apply the term " atoms.'' Atoms, therefore, make molecules, and molecules mass, "We have learned that the molecules in forming mass by aggregating are held together by the force of attraction, and that this force is restricted to molecules. Now, the force which unites atoms to form molecules is a very different one from the molecular, and is only exerted among or between atoms. The Atomic Force. — When a molecule has been resolved into its constituent atoms the process of subdivision has been carried to its utmost extent. The resolution of mole- cules into atoms usually gives us several kinds of atoms, and, because the atoms represent the ultimate division of matter, when we have different kinds of atoms we must have different kinds of matter. Chemists have found that there are between 65 and 70 different kinds of atoms, and consequently there must be as many different ultimate kinds of matter. Such an ultimate kind of matter, which, when its molecule is resolved into atoms, yields only one kind of atoms, is termed an elemsnt, or a simple substance. These 65 or 70 simple substances unite with each other in various proportions, and form the innumerable diversity of substances and bodies in the universe. This union is in obedience to the chemical or atomic force, or chemical affinity, or chemism, and takes place only between atoms. Apparently molecules unite with each other chemically at times; the union is, however, between the atoms constitut- ing the molecules. There is as sharp a distinction between the molecular and atomic forces as there is between a mole- cule and an atom. When molecules unite to form a mass the latter has all the properties which the molecules had, or vice versa, but whcD atoms unite, the resulting molecules have no properties in common with the atoms which 4 PHARMACEUTICAL AN^D MEDICAL CHEMISTRY. formed them. In other words, when atoms unite with one another they lose their identity, their individuality, and the resulting molecules are totally different in all respects. For instance, if we unite a molecule of iron with another molecule of iron, we get a mass of iron, which still retains all the properties of the iron; but if we unite an atom of iron with an atom of iodine, we get a molecule of iodide of iron, which is totally different from either the iron or the iodine. In the latter union the chemical force exerts itself, in the former the molecular. The student will thus far remember: That atoms are the smallest particles of matter which will enter into chemical union, and That this chemical union destroys the identity of the kind of matter acted upon, forming bodies altogether dif- ferent from those entering into their composition. That the chemical force is that force which induces and governs that kind of union. That molecules are the smallest particles of matter which can retain the properties of the mass of which they are a part, and That they are held together by the molecular force. Physics relates to the study of bodies in which there is no change in composition. Chemistry studies the phenomena observed in bodies in which there is a change in structure, and the law inducing the change. The Elements. The 65 or 70 simple bodies or elements in an innumer- able variety of combinations — chemical combinations — make up the sum of matter of the earth and all upon it. PHARMACEUTICAL AKD MEDICAL CHEMISTRY. 5 In thus uniting to form this diversity of bodies, the ele- m^its behave principally in one of two ways (these ways will be alluded to later, when the student will have be- come better j&tted to understand them), which ways afford us a convenient means for subdivision into two primary groups — the metals and non-metals. Each of these is for convenience further subdivided into smaller groups, the elements of each group having some property or properties in common, which makes their classification desirable. The names of the elements are derived from the Greek and Latin, and usually indicate something of the nature of the element. For convenience and brevity symbols are employed in place of the whole names, these symbols being shorthand for the longer Greek or Latin names. Of the whole number of elements a few more than half are im- portant enough to merit mention here, the remainder being of rare occurrence. The following represents a convenient classification of the elements into groups and sub-groups : NOK-METALS. Names. Symbols. Oxygen ] Sulphur S r^ Selenium Se ^ Oxygen group. Tellurium Te J Chlorine. Cn Bromine Br tt i Iodine I ^ Halogen group. Fluorine Fl J Phosphorus , P '] Carbon , C I Silicon Si \- Boron ; .Bo | Nitrogen N J Arsenic , As Antimony (Stibium) Sb )- Metalloids. Bismuth Bi 6 PHARMACEUTICAL AKt) MEDICAL CHEMISTRY. Metals. Names. Symbols. Potassium (Kalium) K "] Sodium (Natrium) Na .,, ,. Lithium. : Li (^ Alkalies. Ammonium (NH4) Calcium Ca Barium Ba ^ Alkaline earths. Strontium Sr I Magnesium Mg Zinc Zn ^ Magnesium group. Cadmium Cd Silver (Argentum) Ag Mercury (Hydrargyrum) Hg \ Copper group. Copper (Cuprum) Cu Iron (Ferrum) Fe ") Sr!r-:;;:::;:;;;.::::::::;.v;;.v;;:^o [ '- ^-p- Nickel Ni J Chromium Cr ) r^\ Molybdenum Mo j- Chromium group. ffsmX".^'!'':r^.;;;;:;::::;:;::;;;;;;.l'^ elJd (Sumj: : : ::::::::::::::::::■.:::::: II \ p>-«-- g^-p^ Aluminum Al Lead (Plumbum) Pb Tin (Stannum) ... Sn Hydrogen H The above, it must be remembered, are not all the ele- ments known, nor are those mentioned in any one group all that may belong to that group; they are the more im- portant ones. It will be seen that antimony and bismuth are found in both primary divisions — these and the metal- loids will be considered further on. The student at this point need only remember the names and symbols of the elements and the two primary divisions. PHARMACEUTICAL AKD MEDICAL CHEMISTRY. 7 Physical Properties of the Elements. The elements, as elements, exist in three forms; some are solid, some liquid and some gaseous. Mercury and bromine are liquid. Hydrogen, oxygen, chlorine, nitrogen and fluorine are gases, all the rest solids. The condition in which an element, or for that matter any compound, ex- ists, is dependent upon the prevailing temperature. Many solids can be made to become liquid by the application of heat, and liquids to become gaseous. By the withdrawal of heat gases can be liquefied and liquids solidified. Oxygen can be liquefied by pressure and cold. Mercury will be- come solid, just as water will, if the temperature is low enough. On the other hand, mercury and water and other elements or compounds can be changed into gases by heat, in which condition they will remain as long as the temperature is not lowered. Most of the elements are insoluble, odorless and taste- less. Sodium and potassium are soluble in water, uniting chemically with the water. Chlorine and bromine have very characteristic odors. Nearly all have considerable chemical affinity, for which reason so few are found in nature in the elementary con- dition. A few exceptions are nitrogen, gold and copper. Sometimes an element occurs in more than one form, as carbon, with which we are familiar in the form of the diamond, graphite and charcoal; and oxygen, which some- times assumes a nature which makes ozone of it. These COiiditions are termed allotropic, and are probably due to the different arrangement of atoms in the molecules. Two atoms of oxygen make a molecule of oxygen, but if the molecule contains three atoms of oxygen we call it ozone. 8 PHABMACEUTICAL AKD MEDICAL CHEMISTKY. In this case the molecules contain different numbers of atoms, but when the number of atoms in the molecule is the same, the difference is in the arrangement of the atoms in the molecule. While some elements are crystal- lized — that is, assuming a definite geometrical outline — others are amorphous, just the contrary — that is, without any regular shape. The metallic elements usually have a lustre, a color from the white silver to the bluish-gray lead, excepting copper, which is red, and gold, yellow. They differ con- siderably in their relative weights, hydrogen being the lightest and platinum the heaviest. The metals are, as a rule, heavy — platinum being 21^ times as heavy as water. Lithium, sodium, and potassium are lighter than water. Chemical Properties of the Elements. Atomic Weights and the Lav^^ of Defi]!^ite Chemi- cal Peoportioi^. — In studying the chemical behavior of the elements we enter upon the field of chemistry proper, and concern ourselves almost wholly with the atomic force, the force binding together the atoms to form compounds. The atomic force, or chemical affinity, as it is frequently called, exerts itself at the point of contact of two or more atoms — that is, if the elements are capable of forming a compound; for it must be understood that chemical affinity does not exert itself upon or between any two or more atoms. This chemical union does not take place in a hap- hazard way; on the contrary, certain definite laws govern it. If we were to unite hydrogen and oxygen, we would find that the union takes place between definite quanti- ties of the elements, and that if either were in excess of PHARMACEUTICAL AKD MEDICAL CHEMISTRY. 9 its definite quantity, so much of either would remain over as either was in excess of its definite quantity. For illustration, let us observe closely the proportions in which hydrogen and oxygen will unite. Both are gases, but we may nevertheless weigh them, and in so doing, which is necessary, we find that hydrogen weighs less than oxygen does, bulk for bulk. If we are careful to take an equal volume of each gas, the hydrogen will be found to weigh just one-sixteenth as much as the oxygen does; or, on the other hand, that oxygen is 16 times heavier than hydro- gen. Let the student bear this in mind for the present. The weights of equal volumes of the two gases may have been found to have been of hydrogen 10, and of oxygen 160 grains. If these two equal volumes were made to unite chemically (by touching the mixture with a lighted match), it would be found that all of the hydrogen, but only half the oxygen, entered into chemical union; in other words, that the 10 grains of the hydrogen united with 80 grains of the oxygen, and that the other 80 grains of oxygen remained unaffected. This experiment might be repeated with any desired quantity of the two gases, but always with the result that they would unite in the pro- portion of 1 of hydrogen and 8 of oxygen ly weight, or 2 of hydrogen and 1 of oxygen by volume, and that if either be in excess of these proportions, that excess will not be affected, but will remain unchanged. The product of this combination is water. In like manner we could induce chemical union between hydrogen and chlorine, and the definite chemical proportions would be 1 and 35-1^, respectively, by weight, or 1 and 1 hy volume. This product would be hydrochloric acid. In the case of hydrogen and sulphur in the gaseous con- 10 PHARMACEUTICAL AKD MEDICAL CHEMISTRY. dition, the proportions hy weight would be, of hydrogen 1 and sulphur 16, or hy volume, 2 of hydrogen and 1 of sulphur. Chemists have assumed that all elements in the gaseous condition contain in equal volumes, under like conditions, an equal number of molecules, and that molecules of ele- ments usually consist of two atoms, and that, therefore, equal volumes of most elements in the gaseous condition contain an equal number of atoms. The weights of atoms must, according to this, differ to the extent that equal volumes of gases differ in weight. Hydrogen is the light- est gas, and if equal volumes of oxygen, chlorine and sul- phur are, respectively, 16, 35.5 and 32 times heavier than hydrogen, and if we give the hydrogen atom the value of 1, it is obvious that the weights of the atoms of oxygen, chlorine and sulphur must necessarily be 16, 35.5 and 32. These figures, therefore, represent the atomic weights of these elements. It must be understood that these weights are relative. These figures denote not only the atomic weights of the elements, but they denote also the propor- tions in which they will unite with one or more hydrogen atoms. Oxygen will unite in the proportion of 16 with 2 of hydrogen, chlorine of 35.5 with 1 of hydrogen, and sul- phur of 32 with 2 of hydrogen, for the reasons stated and others that will be stated further on. In this wise the atomic weights of all elements have been obtained, in comparing their weights to that of hydrogen, either directly or indirectly. Another method will be spoken of a little further on. Law of Multiple Proportioks.— The student must bear in mind also that the proportions in which elements unite with hydrogen are the proportions in which they will PHAEMACEUTICAL AND MEDICAL CHEMISTRY. 11 unite with one another. Oxygen will therefore unite with sulphur in the proportion of 16 to 32. The atomic weight of carbon is found to be 12, of phosphorus 31, of nitrogen 14. Carbon, phosphorus or nitrogen would therefore unite with 16 parts of oxygen in the proportions expressed by the numbers expressing their atomic weights. We find, though, that these proportions — i.e., those expressed by the atomic weights — are not the only ones in which these elements will unite. If, in the case of carbon and oxygen, 32 of oxygen, twice 16, were taken, chemical combination would ensue, with the formation of a definite compound. Nitrogen and oxygen will unite not only in the proportion of 14 and 16, but in such a way that multiple proportions of the oxygen with a constant proportion of nitrogen will form definite compounds. The known combinations of nitrogen and oxygen may serve to illustrate : Nitrogen monoxide. Nitrogen dioxide. . . Nitrogen trioxide. . . Nitrogen tetroxide . . Nitrogen pentoxide. By weight. j Nitrogen 28 parts. ( Oxygen 16 parts. ( Nitrogen 28 parts. ( Oxygen 32 parts. j Nitrogen 28 parts. (Oxygen 48 parts. j Nitrogen 28 parts. (Oxygen 64 parts. j Nitrogen 28 parts. ( Oxygen. 80 parts. The prefixes mono, di, tri, tetra, and penta (oxide) here mean, respectively, one, two, three, four and five times one oxygen. It will be seen that the proportion of nitrogen (28, twice 14) is constant, while the quantity of oxygen increases by 16 in the ratio of one, two, three, four and five times 16. 12 PHAKMACEUTICAL Ai^D MEDICAL CHEMISTRY. Carbon and oxygen unite in these proportions: Carbon 12, and oxygen 16, form carbon monoxide. Carbon 12, and oxygen 32, form carbon dioxide. This evidences the important law that some elements unite in more than one pro'portion, and that the resulting definite compoio7ids contain, to a constant proportion of one of the elements, multiple ^proportions of the other. Carbon monoxide always contains certain fixed and defi- nite proportions of carbon and oxygen; it cannot be car- bon monoxide if it does not. This is true also of the carbon dioxide. All definite compounds consist of the same elements in the same proportions, according to our first law, and according to the second law, if two elements unite in more than one proportion, they unite in multi- ples of that proportion, and never in intermediate propor- tions. Quantivalence. We have learned that hydrogen was taken as a standard in comparing the weights of atoms of the elements. This is not its only function as a standard ; it is also employed in establishing the quantivalence or value of atoms in replacing other atoms in combination. All atoms have value, and these values are constant in most atoms. We assume that all atoms have bonds with which they unite with each other, and that the number of bonds fixes the value of the atom in combining power. So hydrogen and chlorine unite atom for atom. So do hydrogen and iodine. These atoms have equal values. Hydrogen and oxygen unite in the proportion of two atoms of the former to one of the latter; three of hydrogen combine with one of arsenic; four of hydrogen combine with one of carbon. The oxy- PHAEMACEUTICAL Al^B MEDICAL CHEMISTRY. 13 gen atom has twice the value of hydrogen, arsenic thrice, and carbon four times the value. Oxygen, having twice the value of hydrogen or of any element uniting with hydrogen atom for atom, is said to have two bonds, each one of which combines with the one bond which each hydrogen atom has. Arsenic, because it requires three of hydrogen for combination, is said to have three bonds, and carbon, for similar reason, to have four bonds. The number of hydrogen atoms the atom of another element requires for combination (in case of pos- sibility of combination) determines the number of bonds that atom has : Hydrochloric Arseniuretted Methane or acid. Water. hydrogen. marsh gas. H H H— 01 H— 0— H H— As— H H— C— H i The value of an atom is not ascertained alone by study- ing the number of hydrogen atoms it requires for com- bination, but also by observing the number of other atoms it can replace in combination. In the above H — — H one of the hydrogen atoms can be re2olaced by one atom of potassium or one of sodium, hence the sodium and potas- sium atoms have the same value which the hydrogen atom has. If the oxygen were replaced by sulphur, H — S — H, the sulphur would have two bonds, because it replaced the oxygen, which needed two atoms of hydrogen for combina- tion. The two hydrogen atoms might be replaced by one of calcium, Oa=0, therefore calcium would have two bonds. Any atom that could replace the calcium would 14 PHARMACEUTICAL AKD MEDICAL CHEMISTRY. be twice the value of the hydrogen atom in combining power, for the same reason. The value of atoms might be better understood by assuming that the hydrogen atom is a quarter of a dollar, the standard, oxygen half a dollar piece, and carbon a dollar. To equal the dollar (carbon) with quarters (hydrogen), four of the latter would be re- quired; to equal the half dollar (oxygen) with quarters (hydrogen), two of the latter would be needed, and to equal the dollar (carbon) with half dollars (oxygen), two would be required. Special terms are used to designate the value of atoms. Those having the value of hydrogen are termed monads, or they are said to be monatomic {mono, one), or uni- valent (unus, one); those combining with or replacing two of hydrogen, diads (di, two) or diatomic, or bivalent {his, two); those having thrice the value of the hydro- gen atom are termed triads {tres, three), triatomic or trivalent; the next in order are quadrads or tetrads {quadra, four), quadrivalent', pentads {penta, five), or pentatomic; hexads (six); septads (seven), etc. Atomicity and equivalency are terms synonymous with quantivalence and valence, but the term quantivalence is to be preferred. The subjoined table gives the names of the elements, their symbols, quantivalence and atomic weights. The student will notice that many of the elements are classed in more than one column. Those elements have more than one value — they have as many as the table gives them. When an atom has more than one value, the values will always be expressed by even numbers or by uneven numbers, never by both. Thus nitrogen is triad, pentad and sometimes septod, but it never has two, four or six PHARMACEUTICAL AND MEDICAL CHEMISTRY. 15 bdnds. In cases where the atomic weight is expressed by fractions, the student may remember the nearest whole number. Elements — ftuantivalence, Symbols, Atomic Weights. Monads. Diads. Triads. Tetrads. a A N 1 0) 1 A Hydrogen, Oxygen, 0, 16 Nitrogen, Carbon, S c\ H. 1 Sulphur, S, 32 N, 14.01 C, 12 P Fe Br Chlorine, Calcium, Phosphorus, Silicon, CI Al I CI. 35.37 Ca, 39.91 P, 30.96 Si, 28.3 Br Cr Bromine, Magnesium, Gold. Platinum, I Co Br, 79.76 Mg, 24.3 Au, 196.7 Pt, 194.3 As Ni Iodine, Copper, Arsenic, Fe Sb Mn I, 126.53 Cu, 63.18 As, 74.9 Al Bi Fluorine, Zinc, Zn, 65.1 Antimony, Mn Fl, 19 Strontium, Sb, 119.6 Cr Sodium, Sr, 87.3 Bismuth, Co Na, 23 Cadmium, Bi, 208.9 Ni Potassium, Cd, 111.5 CI Ca K, 39.03 Mercury, Br Ba Rubidium, Hg, 199.8 I S Rb, 85.20 Tin, Sn, 118.8 Pb Silver, Barium, Ag, 107.66 Ba, 136.9 Caesium, Lead, Cs, 132.7 Pb, 206.4 Iron, Fe, 55.88 Aluminum, Al, 27.04 Manganese, Mn, 54.08 Chromium, Cr, 52 Cobalt, Co, 58.6 Nickel, Ni,58.6 16 PHARMACEUTICAL AND MEDICAL CHEMISTRY. Chemical Notation. Chemical notation is the recording, by means of symbols, the chemical changes, or the migrations of atoms or mole- cules in either the formation or the resolution of com- pounds; in short, it is the symbolizing of chemical facts. We have already employed the first capital letter of the Latin or Greek names of the elements as shorthand for the whole name. Thus, for hydrogen or oxygen, we simply write H and 0. This is not the only function of the sym- bol (to represent the name of the element); it means, furthermore, one atom of the element, and third, one volume of the element in the gaseous condition. A fourth office is to represent a constant comhining weight — i.e., the atomic weight of the element for which it stands. Figures are used to modify some of these functions. Large figures placed before a symbol multiply the atoms, and therefore also the atomic weights and the volumes in gaseous condition. Thus, 2H means two atoms of hydro- gen, two volumes, and twice the atomic weight also. A small figure written to the right of the symbol, below, has the same significance; thus H^ is the same as 2H. A figure preceding multiplies all the symbols that follow, as 3HC1 means three of hydrogen and three of chlorine, but a small figure at the lower right of a symbol multiplies only the symbol to which it is attached. It would really be incor- rect to write 2H, as we would thereby mean two atoms of hydrogen uncombined, which cannot thus exist; atoms, even of one kind, will combine to form molecules, two atoms usually forming one molecule, which molecule in the case of hydrogen or oxygen would be expressed : H^ or O^. The third function of a symbol, that of representing one PHAEMACEUTICAL AND MEDICAL CHEMISTRY. 17 volume of the element in the state of gas, will perhaps not be so easily understood by the student. By referring to the fourth function, representing the atomic weight, he may the better understand it. In learning the atomic weights, the student was informed that they were obtained by weighing equal volumes of the elements under like con- ditions of pressure, etc., after they had been caused to enter the gaseous condition, and that the number expressing the number of times the volume of any one gas was heavier than an equal volume of hydrogen, the standard, expressed the atomic weight of that element, for equal volumes of gases in the case of elementary bodies contain equal numbers of molecules; and because these, the molecules, contain two atoms the volumes must contain equal numbers of atoms. The extension or bulk of the volume is arbitrary, so long as it be equal to that with which it is compared. The position of symbols, too, has some significance. HjjO means not only two atoms of hydrogen and one of oxygen, etc., but also that the H and are united by chemical force and in the proportion expressed by the fig- ures 2 and 1, respectively. (1 is always understood, and therefore never written.) Written 211^ -(- 0,, it would in- dicate a mere mechanical mixture of two molecules of hydrogen and one molecule of oxygen, but placed closely together it is understood that they represent the compound resulting when hydrogen and oxygen unite chemically. An atom is represented by a single symbol, but a 'mole- cule, which consists of not less than two atoms, is repre- sented by as many symbols as it has kinds of atoms in its composition, and the collection of symbols representing the composition of a molecule is called its formula. The formula for a molecule of an element has only a single 18 PHARMACEUTICAL AN^D MEDICAL CHEMISTRY. symbol, representing the kind of atoms, together with the small figure at the lower right side denoting the number of atoms; thus, H^, 0^, Cl^ denote molecules of hydrogen, oxygen and chlorine, respectively. The molecules of some elements have more than two atoms; phosphorus, P, is believed to have four. The formula for the molecule of a compound must have not less than two kinds of atoms. Calcium carbonate, common chalk, contains calcium, carbon and oxygen, and its formula is CaCOg — that is, one atom of calcium, one of carbon, and three of oxygen — and these elements are united in the proportions (definite proportions) expressed by their atomic weights. The formula for the molecule of water is H^O, for hydrochloric acid, HOI. The latter may be made by inducing chemical union between the constituent ele- ments; this union may be thus recorded : H^ + Cl^ = 2H01, and such a series of formulas is called an equation. An equation is, therefore, the illustration by means of sym- bols of the chemical union or resolution of atoms or molecules. We say chemical resolution, for it is just as possible to resolve a compound into its constituent elements as it is to cause elements to unite. 2HC1 = H^ -f- Cl^ would be an equation illustrating chemical resolution. In all equations the kinds and numbers of atoms to the left of the sign of equality must always equal those to the right of it. It may be appropriately mentioned here that chemical resolution is also termed analysis, and chemical union, synthesis. Analysis and synthesis have usually given to them a broader significance. Analysis does not necessarily mean alone to break up compound substances into their elements, it means also that a complex combination may PHARMACEUTICAL AND MEDICAL CHEMISTRY. 19 be broken up into two or more simpler ones. Chemical processes and methods by which we recognize an element, or a group of elements, are termed chemical analyses, whereas chemical synthesis is the putting together, by means of chemical force, elements to form compounds, or uniting simpler compounds to form more complex ones. By heating mercuric oxide, HgO, the two elements be- come dissociated. The analysis may be thus expressed: 2HgO + heat = Hg^ + O^. This is one form of analysis; another may be illustrated by heating calcium carbonate: CaCOg + heat == CaO + COj. In the former the product of the analysis is the elements; in the latter, compounds which are simpler than the one they made up, A simple form of synthesis is illustrated by bringing iodine and iron in contact for some time — iodide of iron is formed according to this equation : Fe, + 2I3 = 2FeIj. Another form of synthesis in which simple compounds are employed may be symbolized in this equation: SO^ + H,0 = H2SO3. The sulphur dioxide unites with the hydrogen oxide, water, to form sulphurous acid. Much more, for which the student is not yet ready, will be said about chemical notation and chemical nomencla- ture as the student advances. The functions of symbols, formulas and equation may be briefly summarized : A symbol is: (1) shorthand for the name of the element which it represents; (2) it represents one atom of that element; (3) one volume of that element in the gaseous condition; (4) it means a definite chemical proportion or atomic weight. A formula gives (1) the names of the elements in the molecule; (2) the number of atoms in the molecule; (3) 20 PHARMACEUTICAL AND MEDICAL CHEMISTRY. the molecular weight or sum of the atomic weights; (4) it represents two volumes of the substance in state of gas, and (5) denotes that the atoms in the molecule are united by chemical force. The function of an equation is to express by symbols the changes that take place among atoms and molecules in analysis or synthesis. PHARMACEUTICAL AKD MEDICAL CHEMISTRY. 21 The Non-metallic Elements. Before entering upon the study of the non-metallic ele- ments it is advisable for the student to review all he has studied up to the present time, so as to insure a thorough understanding of that which is to follow. It is imperative to have a good foundation to build upon, and it will be well worth the student^s time to read over several times the principles of chemistry considered in previous pages. The physical differences between non-metals and metals are obvious. Every one knows that iron and silver are metals. We can tell by their appearance, weight and lustre. It is just as obvious that the constituents of the air, oxygen and nitrogen, are not metals, and because they are not metals we call them non-metals. There is, how- ever, no very clear line of distinction in Nature between these two subdivisions of the elements as they pass gradu- ally into each other. The metalloids^ bismuth, arsenic and antimony, may be classed in either division. They are called metalloids because they are like the metals in some respects. Oxygen. History. — It is appropriate that we begin the study of the chemical bodies with the most remarkable and impor- tant element — oxygen. It was discovered simultaneously in 1774 by Dr. Priestley, of England, and a young apothecary by the name of Scheele, in Sweden. Lavoisier, the distin- guished French chemist, proved the identity of the gas dis- covered by Priestley and Scheele, but did not discover it, as is stated by some. Priestley was one day concentrating 22 PHARMACEUTICAL AN"D MEDICAL CHEMISTRY. the sun^s rays by means of a burning glass, and directed the focus upon some red oxide of mercury, when, to his surprise, the oxide began to resolve itself into a gas and metallic mercury. The gas was afterward proven to be an element. Scheele, about the same time, heated a quantity of dioxide of manganese — a stone occurring abundantly in the locality of his home, and called hraunstein, i.e., brown- stone — with a result similar to that which Priestley had ob- tained. It is remarkable that this gas should have been discovered by two different men, independent of one another, at the same time. The discovery of oxygen marked the beginning of the development of chemical science — it was, indeed, the birth of chemistry as a science. It was the beginning of the unveiling of Nature^s most hidden secrets — the deliverance of chemistry from the bondage of the ridiculous, pretended science of alchemy. Occurrence in Nature. — Oxygen occurs everywhere in Nature. The three kingdoms are largely made up of it. It is the most widely-distributed and the most abundant element we have. The universe is computed to be made up of : Oxygen 48 per cent. Silicon 36 Aluminum 6 Calcium together 9 Magnesium Sodium Potassium Iron The rest of the elements 1 100 per cent. PHARMACEUTICAL AND MEDICAL CHEMISTRY. 23 Water is 88 per cent, oxygen; air, 20 per cent. Fifty per cent, of all the rocks is oxygen; from 60 to 80 per cent, of plants and animals is oxygen. In short, it is present almost everywhere and in everything. We know that oxygen is continually being produced by plants, these taking in the carbonic acid gas present in the air, resolving this into its constituent elements, carbon and oxygen, retaining the former and fixing it in their tissue, and liberating or setting free the oxygen. Preparation. — It may be prepared to-day as Priestley and Scheele prepared it over a century ago. By heating mercuric oxide it is readily obtained, according to this equation: Mercuric oxide. Mercury. Oxygen. 2HgO + heat = Hg, + 0, It may be heated in a test-tube with a perforated cork inserted, through which a bent glass tube passes, to afford a means of collecting the gas as it is generated. To collect the gas it is necessary to pass it into an inverted vessel, as a bottle filled with water, the mouth of the bottle being under water. The gas will pass upward and displace the water — that is, it is collected over water. Heating dioxide of manganese will produce the same result, according to this equation : Dioxide of Tetroxide of manganese. Manganese. Oxygen. 3MnO, -f heat = Mn,0, + 0, A more ready method is heating chlorate of potassium, contained in a test-tube or other suitable apparatus with 24 PHARMACEUTICAL AKD MEBICAL CHEMISTRY. the necessary fitting. This equation expresses the libera- tion of oxygen by this method : Potassic chlorate. Potassic coloride. Oxygen. 2KCIO3 + heat = 2KC1 + 30, In the latter method less heat is required than in either of the former two, but care must be exercised because of the explosiveness of the chlorate. If the chlorate is mixed with an equal weight of dioxide of manganese the evolution of oxygen occurs at a very low temperature, so that very little heat is required. In this mixture the dioxide of manganese does not yield any gas, as it decomposes at a much higher temperature; it acts by its presence only. Such substances, which take no part in a change like the above, are sometimes said to act by cataly- sis — that is, by their presence only. Their presence furnishes angles, and angles always facilitate the escape of gases. Physical Properties. — Oxygen is a colorless, invisible gas, without odor, weighing 16 times as much as hydrogen, wherefore its atomic weight or specific gravity is 16. Its molecular weight is 32 — twice its atomic weight. It has been liquefied by extreme pressure and reduction of tem- perature. It is soluble to the extent of 5 per cent, in water. This 5 per cent, sustains the life of fishes. Chemical Properties. — Oxygen has such chemical affinity that it combines with every element with the exception of fluorine. It oxidizes all the elements. The act of com- bination is called oxidation, and the products formed, oxides. If carbon, sulphur or phosphorus be burned in oxygen, the resulting oxides, 00^, SO, and PjO^, when dis- PHARMACEUTICAL AND MEDICAL CHEMISTRY. 25 solved in water form the corresponding acids, carbonic, sul- phurous and phosphoric, thus: 00, + H,0 = H,003 SO, + H,0 = H,S03 P,0, + 3H,0 = 2H3PO, This fact was noticed by the early experimenters, and be- lieving they had found the " acid generator," they gave it the name "oxygen," which means "acid generator." Later chemists learned, though, that it is not oxygen but hydrogen (which means " water generator ") which is the essential constituent of acids. Burning is a chemical process, oxidation, in which the chemical union between the burning body and oxygen is so intense that heat and flame are evolved. The more rapid and complete the oxidation the more luminous is the flame produced. Such a form of oxidation is termed combustion. Substances which burn in air burn with more brilliancy in oxygen, which fact is employed in recognizing oxygen. A glowing piece of wood is instantly relighted into a bright flame in oxygen. Oxygen is the supporter of life; taken in through the lungs it causes the slow combustion of various organic substances in the living animal. It slowly oxidizes these bodies, which are mainly refuse, changing them into gases, which are eliminated during exhalation. It is not necessary for the oxygen to be in its elementary condition to enter into combination or to oxidize bodies. Some substances contain the oxygen so loosely combined that they readily part with it when they come in contact with bodies capable of being oxidized. The symbol for oxygen is 0; atomic weight, 16; molec- ular weight, 32. 26 PHARMACEUTICAL AIS'D MEDICAL CHEMISTRY. Uses and Compounds in Pharmacy and Medicine. — There are no direct uses for oxygen in pharmacy, excepting that it is kept in some pharmacies for physicians' use. Its compounds with other elements receive attention under the mineral acids and elsewhere. Tests and Experiments. — When things burn in air they take up or unite with oxygen. Coal, when it burns, takes up or unites with the oxygen of the air, forming carbonic acid gas, thus: C^ -1- 20^ = 200^. This equation repre- sents all the usual forms of combustion, and combustion is generally defined as the union of an element (usually carbon) with oxygen, with the production of a flame. The products of such combustion are oxides. It must be remembered that one-fifth of the air is oxygen, and that if combustion takes place with such an amount of oxygen, it will be very much more intense in pure oxygen. All sub- stances which burn in air burn with very greatly increased brilliancy in the pure gas. If we should introduce a glow- ing piece of wood into oxygen, prepared as above, it would immediately relight and burn with extreme vividness. Charcoal, which ordinarily only glows, burns with a very bright fiame in oxygen, forming CO^, carbonic acid gas; sulphur gives a beautiful blue flame, forming sulphur di- oxide (gas), SO^; phosphorus burns with a blinding bright- ness in oxygen, producing phosphoric oxide, PjOj iron burns with beautiful scintillations, forming ferric oxide, Fe^Oj. Substances ordinarily incombustible in air burn with surprising brilliancy in oxygen. In all these cases the effects are due simply to the union of the burning body with the oxygen, forming oxides. This union is in obedience to the laws of chemical union already depicted, and if we would weigh the bodies and the oxygen in each case, we would PHARMACEUTICAL AND MEDICAL CHEMISTRY. 27 find these laws verified experimentally. These experiments are all oxidations, and the products formed oxides. Ozone. Ozone is a peculiar modification of oxygen. If a series of electric discharges is passed through oxygen the latter becomes modified in a manner that makes ozone of it. Ozone is an allotropic (another form) form of oxygen, a form which is sometimes designated as the active state of oxygen, while the ordinary oxygen is in the passive state. Ozone has a characteristic odor, especially noticeable after electrical discharges. Oxygen becomes diminished in volume if a number of electric discharges are passed through it, and experiments have proved that ozone is one and a half times as heavy as oxygen, three volumes of oxygen becoming two volumes of ozone. The atomic weight of ozone is correspondingly found to be 24, oxygen being 16; or the molecule of ozone may be looked upon as containing 3 atoms of oxygen 0.^ = / \ while the mole- 0—0 cule of oxygen contains only 2 atoms, 0, = — 0. Ozone has very marked oxidizing properties, exceeding those of oxygen. It occurs in the air to some extent and may be detected in it by its power to liberate iodine from potassium iodide by oxidizing the potassium. For this ex- periment white filtering-paper may be saturated with solu- tion of potassium iodide containing a little boiled starch. The dry paper when it comes in contact with ozone becomes blue, owing to the liberation of iodine from the potassium iodide, and the reaction ensuing between the iodine and starch, which produce the blue iodide of starch. Other 28 PHARMACEUTICAL AND MEDICAL CHEMISTRY. gases exercise this same oxidizing effect (e.g., the oxides of nitrogen, and hydrogen dioxide). Ozone may be distin- guished from these in that it is converted into ordinary oxygen when passed through a heated tube, which is not the case with the other oxidizing gases. Ozone is also produced when strong sulphuric acid acts upon potassium permanganate, or when phosphorus is slowly oxidized in moist air. Hydrogen. History. — Hydrogen was discovered by Cavendish in 1766, who also was first to describe it as an element and to prove that it was a constituent of water. By some it is stated that Paracelsus obtained it in the sixteenth century, but Cavendish first recognized its elementary nature. Occurrence in Nature. — Hydrogen is never found free, on account of its intense chemical affinity, but in count- less combinations it exists widely distributed in Nature. it forms one-ninth by weight of water; with nitrogen it forms ammonia, NH3, which is of considerable pharma- ceutical importance; it constitutes a large proportion of all organized bodies, and it is found in products of decom.- position, in shooting stars and in volcanic gases in the free state, but does not remain so long, usually combining with the oxygen in the air. Source. — The usual source of hydrogen is water, from which it is obtained in various ways, some of which are described in the following paragraphs. Preparation. — If an electric current is passed through water it effects a decomposition of the water according to this equation : 2B.fi -\- electricity = 2Hj -}- O^. PHARMACEUTICAL AND MEDICAL CHEMISTRY. 29 Sodium and potassium as elements also effect the decom- position of water, with liberation of hydrogen and forma- tion of hydroxides of the respective bases, thus: Na, + 3H,0 = 2NaOH + H, K, + 2H,0 - 2K0H + H, A third and the most convenient method of preparing hydrogen is by means of zinc and hydrochloric or sulphuric acid: Zn, + 2H,S0, = 2ZnS0, + 2H,. The zinc, preferably in form of granules, is introduced into a small flask into which is fitted a rubber stopper, through which passes a glass tube, bent at right angles just as it leaves the stopper. The tube should terminate in the flask just below the lower end of the stopper, and should be drawn to a point at its other end. When the sulphuric acid (diluted) comes in contact with the zinc the evolution of hydrogen begins, the gas finding its exit through the tube. It may, like oxygen, be collected over water. The zinc in the flask becomes dissolved, forming sulphate of zinc. There are many other methods for preparing hydrogen, but this is the one usually employed for experimental pur- poses. Physical Properties. — Hydrogen is a colorless, odorless, invisible gas, very inflammaMe, and slightly soluble in water. It is the lightest of all known bodies, and is there- fore employed as the standard of comparison for the atomic weights of all the elements. It is an exceedingly diffusive gas, more so than any other; it will escape through joints of apparatus which are impervious to other gases. It is well to remember that all gases are diffusive, and that they dif- fuse in inverse proportion to the square root of their 30 PHARMACEUTICAL AND MEDICAL CHEMISTRY. sity or specific gravity. Thus oxygen, having a specific gravity or density of 16, will diffuse but one-fourth as fast as hydrogen: = 16, of which the square root is 4; H = 1, of which the square root is 1 ; or^ in other words, hydrogen diffuses four times as fast as oxygen. On account of its extreme lightness it is some- times used for inflating balloons. Hydrogen is a non-sup- porter of combustion, but combustible itself. It will not, like oxygen, support life. Chemical Properties — Tests and Experiments. — If the hydrogen, prepared as above from zinc and sulphuric acid and passed through the glass tube, be brought in con- tact with an ignited match it will burn with a yellowish, nearly non-luminous, but very hot flame. (Care should be taken that all the air has been expelled from the flask to prevent explosion.) This flame is due to the chemical combination of hydrogen with the oxygen in the air, form- ing water in this wise: 2H2 -)- 0^ = 2H2O. When hydro- gen burns it always produces water. There is a very strong affinity between these two gases, and if mixed in any quantity and ignited, violent explosion taken place. In the above experiment only a small portion of hydrogen comes in contact at a time with oxygen. The oxy -hydro- gen blowpipe is an arrangement whereby two volumes of hydrogen are made to meet one volume of oxygen at a point which is the terminus of two tubes conveying the two gases in proper proportions to form water. These pro- portions are the most economical, and produce greatest heat and light; but they may vary within wide limits. The union of the two gases produces a very high tem- PHARMACEUTICAL AI^D MEDICAL CHEMISTRY. 31 perature, one hot enough to melt iron or almost anything. This is a vivid illustration of the intensity vrith which chemical combination sometimes takes place. If soap-bubbles be blown from a bag containing a mix- ture of 2 parts hydrogen and 1 part oxygen, and touched with a match or a candle, they explode with a detonation like that of a pistol-shot. Chemical union is not always spontaneous; in this, as in some other cases, it is necessary to employ an inducing-agent, the flame in this case. If a jar be filled with hydrogen and held with the mouth downward the hydrogen will not escape very readily. A lighted candle introduced into the jar will become extin- guished, while the hydrogen will burn at the mouth of the jar. The candle may be withdrawn, when it will relight, becoming extinguished a second time if introduced into the jar again. This shows hydrogen to be inflammable hut not a supporter of combustion. A great amount of chemical energy is possessed by hydrogen; one part of it by weight will neutralize 35.5 of chlorine, 80 of bromine and 126 of iodine, or as much of any of the elements by weight as is represented by their atomic weights divided by their quantivalence. It will extinguish, therefore, 16 of sulphur — the atomic weight of sulphur being 32, this divided by its quantivalence, 2, in this case, giving 16. Hydrogen is the base in all acids, and may be replaced in them by the alkalies or metals to form salts. In hydro- chloric acid, HCl, the hydrogen may be replaced by sodium, Na, to form sodium chloride, NaCl. Potassium bromide, KBr, as a further illustration, is hydrobromic acid, HBr, in which the H is replaced by potassium, K, 32 PHARMACEUTICAL A^-D MEDICAL CHEMISTRY. Is Htdrogen^ a Metal ? — We are treating of hydrogen now as among the non-metals. It has long been a ques- tion whether it is a metal or a non-metal. Many of its chemical properties would class it with the metals, but its physical properties would place it among the non-metals. Some chemists suggest that it is a metal which exists at the prevailing temperature in the form of a gas, and that if the temperature could be reduced far enough it might be obtained in the form of a liquid or solid. In view of this and the analogy of its behavior to the other metals, many accept hydrogen as a metal. It is here studied among the non-metals for convenience. In the beginning of this course the student learned that all bodies exist in one of the three forms — gaseous, liquid or solid — and that the condition depends upon the pre- dominance of one or the other of the molecular forces, cohesion and repulsion. It is appropriate to mention here that these molecular forces are in their turn de- pendent upon the temperature, heat destroying or les- sening the cohesive and increasing the repulsive force, cold increasing the cohesive and lessening the expansive force. Different bodies are differently affected by different tem- peratures, mercury, for example, being liquid at 32° F., while water becomes solid at that temperature. Uses in Pharmacy. — There are no specific uses in phar- macy for hydrogen, excepting perhaps its employment in some chemical processes, as in the preparation of re- duced iron from ferric hydroxide, etc., or in the application of tests for the purity of some of the pharmacopoeial products. Compounds, — Of the compounds of hydrogen water PHAKMACEUTICAL AKD MEDICAL CHEMISTRY. 33 ranks first and the acids next, the carbohydrates and hydrocarbons (unions with carbon), in the organic world, following. It forms hydrides with some of the elements — PH3, AsHg, SbHg — though it is contended by some that the term is not correctly expressive of the form of combina- tion. It is preferred to call these combinations, PH3, phos- phoretted hydrogen; AsHg, arseniuretted hydrogen, etc. With oxygen it forms, besides water, another compound, H3O2, the hydrogen dioxide or peroxide of hydrogen. The prefix 'per meajis liigli, above, to the fullest extent, and hence 2i, peroxide is a combination containing more oxygen than another compound containing the same elements: H^O, water, is an oxide of hydrogen; H^O^, containing more oxygen, is the peroxide. The same applies to other ele- ments besides oxygen — there are perchlorides, persulphates, etc. Hydroxides — often called hydrates — are also compounds containing hydrogen; they are usually looked upon as water, H,0, H — — H, in which one of the hydrogen atoms is replaced by some other element or base. Potas- sium hydroxide would be K — — H, the K taking the place of one of the hydrogen atoms. Water. Water being an oxide of hydrogen, it is appropriate to treat of it under hydrogen. The importance of water in the economy of nature must be apparent to all, in that it is one of the essentials in the maintenance of all living things — without it there could be no life. It is the most abundant substance in nature 34 PHAEMACEUTICAL A1S"D MEDICAL CHEMISTRY. and in its changes of form from the solid ice to its invisi- ble vapor involves the very history and destiny of the earth. Water is concerned in the majority of chemical processes, and is as indispensable in the laboratory of the chemist as in that of Nature. The indispensability of water was apparent to the ancients, and we readily excuse them for having classified water with their elements, which we all know to have been air, fire, earth and water. The elements of the ancients were supposed to be transforma- ble one to the other; it w^as believed that water could be changed to earth, and vice versa, until a chemist dis- proved that belief by distilling and redistilling a weighed quantity of water in air-tight stills and condensers for more than 100 days, at the end of which time he found that the water had not lost weight nor volume. He em- ployed distilled water, which had not been done by others, they always having obtained a residue which was com- posed of the fixed matter present in all waters, but which they supposed to be transformed water. Composition. — Water is composed of 8 parts by weight of oxygen and 1 part of hydrogen, or, by volume, of 2 of hydrogen and 1 of oxygen; its composition is expressed by the formula H^O. That this is so may be proven in sev- eral ways, the simplest being the decomposition of water by the electric current. The water is contained in an apparatus so arranged that the two gases are set free in separate graduated tubes, which are filled with water. The volume of each gas may be read olf, after decom- position, and will be found to be twice as great for the hydrogen as for the oxygen. If the gases, in the exact proportion as given ofi, are mixed and ignited they will combine with a loud explosion, reforming pure water. PHAKMACEUTICAL AND MEDICAL CHEMISTRY. 35 We have thus two methods of proving the composition of water — the one by analysis, the other by synthesis, or " putting together/' If metallic sodium or potassium be thrown upon water the latter will decompose with such violence as to produce a flame, usually. The oxygen which is liberated seizes upon the metal and forms its oxide, the oxide uniting with water to form the hydroxide : Sodium. Water. Oxide of sodium. Hydrogen. Na, + H,0 = Na,0 + H, Na^O + H,0 = 2NaOH, Sodium hydroxide. Iron, or zinc, when heated to redness, has the same action on water. A process upon which much reliance can be placed for demonstrating the composition of water is that in which pure oxide of copper is reduced by hydrogen, and the water so formed is collected and weighed. Copper oxide. Hydrogen. Water. Copper. CuO + H. = H,0 -r Cu By noting the weight of the oxide of copper before and of the copper after the operation, weighing the hydrogen and finally the water, we can tell the composition by weight of the water formed. The elements of water are separated and reunited in numberless operations in chemistry, and the same thing is going on continually in plants and animals. Indeed, water, constituting four-fifths of the vegetable kingdom and three-fourths of the animal, is the prime .condition of all organization, and the maintenance and continuation of or- 36 PHARMACEUTICAL AND MEDICAL CHEMISTRY. ganic life are largely dependent upon its many transfor- mations and decompositions. General Properties. — Water is a colorless, transparent, tasteless, inodorous, volatile liquid, or solid if the tempera- ture is below 32° F. It is practically incompressible. It evaporates spontaneously at ordinary temperatures, boils at 212° F. (100° C), and freezes at 32° F. It does not ex- pand or contract equally, having its maximum density at 39.2° F. (4° C), and expanding 10 per cent in becoming ice. The weight of 1 c.c. at that temperature is 1 gramme, which is the standard of weight in the metric system. A cubic inch of water weighs at ordinary temperature 252.45 grains, whereas a cubic foot weighs about 1000 avoirdupois ounces. Water in small bulk is colorless, but in mass it is blue, like the atmosphere. The admixture of the slightest quantity of some substances destroys the color. Water never occurs in nature in a state of absolute purity. It always contains some dissolved matter, usually saline, sometimes organic. All natural waiers contain in solution the hicarhonates, chlorides and sulphates of sodium, potassium, calcium, magnesium, and often iron and silica. The only absolutely pure water is that obtained by distillation. Rain-water, even, evaporated from the sea and condensed in the air, descending through the atmosphere, becomes charged with the soluble impurities present in the air, such as am-, monia, carbonic acid gas, etc., and hence is not absolutely pure. Chemical Properties. — Water forms hydroxides when brought in contact with many of the oxides, the combina- tions being in some instances so intense that considerable PHARMACEUTICAL AND MEDICAL CHEMISTET. 37 heat is evolved. The hydroxides contain the hydrogen and oxygen in the proportion to form water, but they do not exist as water, the atoms suffering a change of arrange- ment during the union with the bases. Thus, caustic potassa, KOH, or potassic hydroxide, may be looked upon as being composed of K,0 + H,0 {= 2K0H). Sodium hydroxide, 2NaOH, is Na^O and H^O Calcium hydroxide, Ca(0H)2, is CaO and H^O The water is retained in these compounds with such tenacity, that a high heat is necessary to remove it. In case of calcium hydroxide it requires a red heat to expel the water and convert it into the oxide again, while in many other instances the water is held with such force that it cannot be expelled by heat at all. The term hydrate is often used for hydroxide, but it should not be, as hydrate has another specific meaning. Hydrates are bodies, salts, for example, which unite with water without causing an alteration of atomic arrange- ment. The water in such combinations is termed ivater of crystallization, and may be easily removed by compara- tively low heat. Sodium carbonate, for example, has ten molecules of water, which latter may be said to be in juxtaposition to the sodium carbonate, and which can be separated without altering the composition of carbonate proper. The formula is J^a^COg . lOH^O. Heat will re- move the lOH^O, leaving the Na^COj. Salts which do not contain any water of crystallization are anhydrous, so common salt, sodium chloride, NaCl; potassium chlorate, KCIO3, etc., are anhydrous. Cryohy- drates are hydrates which exist only at temperatures below 38 PHARMACEUTICAL AND MEDICAL CHEMISTRY. the freezing point. Sodium chloride, which at ordinary temperatures is anhydrous, becomes a cryohydrate when solidified at about 40 degrees below the freezing point, when it has this formula, 2NaCl . 2IH2O. When the water of crystallization is so feebly united with the salt that it gradually separates at the ordinary temperature, the salt is said to be efflorescent, and the change is called efflorescence. Sodium carbonate crumbles because it is efflorescent — that is, the water is instrumen- tal in the formation of crystals, which lose their shape when the water is expelled, or when it separates spontan- eously. On the other hand, some bodies take up water from the air and become liquefied; such bodies are said to be deli- quescent, and the change is called deliquescence. Calcium chloride is a good example of a deliquescent salt. Water is the very best solvent we have. As a rule, salts are more soluble in hot water than in cold ; notable excep- tions are common salt, which is equally soluble in water at any temperature, and many calcium salts, which are less soluble in hot than in cold water. Water dissolves many of the gases, and therefore also the air, to some extent, but the air dissolved in water has not the same composition as that constituting the atmosphere, which is one-fifth oxygen and four-fifths nitrogen. This is because the oxygen is much more soluble in water than the nitrogen. PHARMACEUTICAL AKD MEDICAL CHEMISTRY. 39 Natural "Waters. These may for convenience be divided into two classes, the atmospheric and the terrestrial, and these classes still further subdivided, thus: Ltmospheric. Terrestrial. Eain Ocean ) Snow Seas V Sa Hail Lakes 1 Fog Lakes Dew Rivers Watery vapor Creeks ^ Fi Brooks > J: 1 Springs Wells , Atmospheric Waters. — Of the atmospheric waters we need not say much. They are all the result of the con- densation of the water evaporated from the surface of the earth. The great specific heat of water has a powerful control- ling influence on the climate. Perhaps the student does not know what specific heat means, and a brief exposition of it may be in order. Equal weights of different bodies at the same temperature require different amounts of heat to raise them to a given degree of temperature. A certain amount of heat is required, for example, to raise 1 pound of water at 100° to 101°; that amount is not the same for all bodies, but varies for every body. The amount of heat required to raise a body one degree in temperature, com- pared to the amount of heat required to raise an equal weight of water through 1°, is that body's specific heat. There are several methods of obtaining the specific heats of bodies. If 1 pound of water having a temperature of 40 PHARMACEUTICAL AND MEDICAL CHEMISTRY. 100° be mixed with 1 pound of Avater of 40°, the 2 pounds will have a mean temperature of 70° : 100 -f 40 = 140, -f- 2 = 70. The first pound of water gives 30° to the water of 40°, making i^hat and becoming itself 70°. This is true if equal portions of any one liquid of different temper- atures are mixed, but if unlike bodies having different temperatures are mixed, a mean temperature does not result. If 1 pound of water of 100° is shaken with 1 pound of mercury at 40°, then, these being unlike bodies, instead of a mean temperate of 70°, the temperature will become 98°. The water lost 2°, an amount sufficient to raise the tem- perature of an equal weight of mercury 58°; that is, from 40° to 98°. It is evident from this that the specific heat of mercury is only -f^, if water is 1. In the first case the 30° of heat which the 100°-water lost raised the tempera- ture of water of 40° to 70°, or every 1° of heat from the water of 100° raised the water at 40° 1°, but in the second case, since the 2° which the water lost were sufficient to raise the pound of mercury through 58°, to raise mercury through 1° would require -f-^ as much heat as water re- quires. Water has the highest specific heat of any body known. The stability of Nature is dependent upon this high spe- cific heat of water. Were it not so, the rapid changes in temperature which would ensue would unfit this globe for habitation. If water could acquire heat with as much facility as mercury does, the seas and water everywhere would freeze and thaw so rapidly and often that all living things would perish from want of adaptation. Terrestrial Waters include all that are on or in the earth; they are divided into the salt and fresh waters. PHARMACEUTICAL AND MEDICAL CHEMISTRY. 41 The ocean, inland seas and some lakes are salt, while all the other divisions are fresh; that is, without salt. The fresh water is further classified into soft and liard water. Hard Waters. — As we have learned, all natural waters contain dissolved matter; this is especially true of terres- trial water, which, while traversing the surface or interior of the earth, becomes charged with the soluble portions of whatever it comes in contact with. If the water contains carbonic acid gas, CO^, its property of dissolving certain bodies is increased. All rocks are soluble to a slight ex- tent in water, but those containing lime, magnesia or iron are more soluble in water containing carbonic acid gas. A water which happens to contain carbonic acid gas freely dissolves limestone, which is calcium carbonate, by converting it into the soluUe hicarlonate : Calcium Carbonic Calcium carbonate. acid. bicarbonate. CaC03 + H,C03 = CaH,(C03), Such water would be called a lia7'd water. Water also dis- solves out of the rocks and soil the sulphate of calcium, CaSO^, and thereby becomes another variety of hard water, known as permanently hard, while the former, containing the bicarbonate of calcium, is termed temporarily hard. These terms express the nature of the water relative to the kind of calcium salt present. Because we can remove the hardness of the water containing the bicarbonate in solu- tion, it is called the temporary hardness, while if due to the sulphate it is ^erm«?^e?^^, because it cannot be remedied. The temporary hardness of water may be removed by boiling or by adding lime-water, a solution of Ca(0H)2 as shown by the following equations : 42 IPHARMACEtJllCAL AKt> MEDICAL CHEMISTRY. Calcium Calcium Carbonic bicarbonate. carbonate. Water, acid gas. CaH,(C03), + heat = CaC03 + H,0 + CQ, Calcium hydroxide. CaH,(C03), -h Ca(OH), = 20^00, + 2H,0 The soluble hicarlonate becomes the insoluble carbonate in both instances, and this precipitates, and in so doing ren- ders the water soft, for the hardness is caused only by the calcium salt being in solution. The use of soap with such water is attended with great loss of soap in the chemical change which takes place in the endeavor to form a lather. Soap with soft water gives a lather at once, but with hard water only after all the calcium salt has been converted into the insoluble calcium soap. The following equations will illustrate the change : Soluble Soap — Sodium. Insoluble Calcium Soap. Sodium palmitate, 2NaCi6H3i- ) (Calcium palmitate, CaCCieHa O2, -f- calcium bicarbonate, )■ = ■{ 02)2, + sodium bicarbonate, CaH2(C03)2 ) ( SNaHCOs. Sodium oleate, 2NaC:sH3302, ) ( Calcium oleate, Ca(Ci8H3302)2, -|- calcium bicarbonate, Ca- > = \ + sodium bicarbonate, 2]Sra- H2(C03)2 ) ( HCO3. Sodium stearate, 2NaCi8H3502, i i Calcium stearate, Ca(Ci8H35, + calcium bicarbonate, Ca- > = \ 02)2, + sodium bicarbonate- H2(C03)2 ) ( 2NaHC03. Ordinary soap is a chemical compound consisting of three definite salts — the palmitate, oleate and stearate of sodium, which, with the soluble lime salt, become con- verted into the corresponding calcium salts, which are insoluble. The greasy scum which floats on hard water which has been treated with soap, is the light and insoluble calcium soap, which gives to the touch the sensation of hardness, whence the name. PHARMACEUTICAL AKD MEDICAL CHEMISTRY. 43 Mineral Waters. — We have learned, and it is worth re- peating, that all natural waters contain dissolved matter, and that spring-water, especially, always contains the chlorides, sulphates and bicarbonates of sodium, potassium, calcium, magnesium and sometimes iron and silica. A mineral luater is one which contains one of these usual constituents in an abnormal or unusual quantity or a sub- stance which is not usually found in natural waters. All the mineral waters scattered over the earth are simply spring waters impregnated, to a greater or less extent, with soluble, substances to which medicinal virtues are attributed. Some waters hold carbonic acid gas in solution, when they are termed sparkling or effervescent, while those without that gas are termed still. When iron is present the water is known q,% ferruginous or chalybeate; others are alhaline, while some are acid. Borax waters are so called because they contain borax, while the name alu7n water is due to the presence of alum in such waters. When much sulphate of sodium (Griauber's salt) is present, or sulphate of magnesium or other salt, we term the water saline. Sulphur ivaters are so called because they contain sulphur, usually in the form of soluble sulphides. Others contain notable quantities of iodine, some bromine, others arsenic, still others lithia, etc. Most of these mineral waters must be used as they are taken from the springs, but a number of them may be evaporated to a small bulk. Well-water. — Wells, unless situated distant from habi- tations, may become dangerous. The soil in which they are dug or driven is usually pervious, so that they may become contaminated with anything with which water trickling from the surface through the soil into them may come in 44 PHARMACEUTICAL AKD MEDICAL CHEMISTRY. contact. Decaying organic matter, the refuse from stables, etc., are dissolved by the water falling upon them as rain, which in its descent through the soil will find its way into the well. This organic matter does not necessarily unfit the water for domestic purposes; the danger lies in its affording a breeding medium for disease germs, which, it is well known, develop rapidly when brought into the system. To test well water or other drinking water for its purity comes within the domain of the pharmacist, though a com- plete and exhaustive analysis should be referred to a skilled chemist. The substances to be looked for primarily are organic matter, albuminoid matter, ammonia and nitrates and nitrites. The nitrogen compounds are usually more abundant if animal matter is present; they, of all other constituents, render water the most unwholesome. The following tests are given here, but the student may omit their application until he will have advanced a little farther. 1. For Organic Matter, — Color a portion of the sample distinctly with a solution of permanganate of potassium and add two or three drops of dilute sulphuric acid. If much organic matter is present the color of the permanga- nate becomes discharged almost immediately; if less, it takes a little longer to decolorize. If the color has not changed in 20 to 30 minutes it is safe to assume that or- ganic matter is not present. This is a tolerably reliable test. 2. For Nitrites. — A little sulphuric acid added to the water containing nitrites forms nitrous acid, which is easily detected by its power to liberate iodine from a solution of iodide of potassium. A little starch paste, made by boiling starch with water, is mixed with a solution of iodide of PHARMACEUTICAL AKD MEDICAL CHEMISTRY. 45 potassium and the whole added to the suspected sample, and if nitrites are present the starch will turn blue with the liberated iodine. This indirect method is a means for detecting nitrites, if present in not too small a quantity. 3. Nitrates are detected by converting into nitric acid, which turns morphine red. A portion of the water is evaporated to dryness, the residue treated with a drop of sulphuric acid, which makes nitric acid of the nitrate, and a portion of morphine added. If nitrates are present a red color will ensue. 4. For Ammo7iia. — Nessler's reagent affords by far the best test. The solution may be made by dissolving 18 grains of iodide of potassium in a little water, adding solution of mercuric chloride until the red iodide first formed redissolves upon agitation. To this are added 50 grains of caustic potassa, and distilled water to make 8 ounces. This reagent will detect 0.00375 grain of ammonia in a pint of water by giving yellow to reddish color. Albuminoid Aimnonia requires a more elaborate process for its detection. If all the above were found it is hardly necessary to go to the trouble of looking for albuminoids; the water would be unwholesome if they were not present. If it is required to test for them, nevertheless. Chapman and Wanklyn^s test may be employed. If the water was found to contain ammonia, this must first be removed, as must also any urea that " may be present. This is best done by distilling the water until it gives no further reaction with Nessler^s solution. Then add a strong solution of caustic potassa and potassium permanganate, and examine again for ammonia. This test depends upon the fact that caustic potassa and permanganate of potassium cause animal mat- 46 PHARMACEUTICAL AND MEDICAL CHEMISTRY. ter, while still in an ambuminoid condition, to unite with hydrogen to form ammonia. These tests are easily applied, but they are only toler- ably reliable. If all respond readily, it is quite safe to assume that impurities are present. If, however, they do not respond satisfactorily, and an important issue is in question, the suspected sample should be referred to an analytical chemist. The Purification of Waters. — Of the methods for purify- ing waters we have already become acquainted with those for hard water. The best general method is that of distil- lation ; all fixed matter remains in the retort, while foreign volatile bodies may be dispelled by boiling previous to dis- tillation. To render water perfectly pure it should be re- distilled in silver vessels. Mechanically suspended organic impurities in water are noxious, rendering water unwholesome and unfit for do- mestic or culinary purposes. It should be stated, however, that when these organic impurities are present (they may be from the drainage of houses, stables, from decaying leaves and animals, from the dust in the air, etc.) they are usually attended by a more or less efficient purifying agent in the form of animalculae (or little animals), which feed upon them. These minute organisms may be viewed through a powerful microscope, when they will exhibit definite yet hideous shapes. There are about 30 species (or more) of them, all performing invaluable service in puri- fying water by consuming dead organic matter, reducing it to its ultimate harmless constituents — carbonic acid gas, ammonia and water. They themselves are harmless, yet, where they can exist, the pathogenic or disease-generating microbes may also flourish. PHAKMACEUTICAL AND MEDICAL CHEMISTRY. 47 Boiling is a simple means of purifying water; it kills animal and vegetable matter (though not all disease germs)^ and expels gases. If lime is in solution it becomes precipi- tated. Turbid or muddy water may be clarified by the addition of a little alum (ten grains to a gallon), which forms with bicarbonate of calcium, which is usually present, a hydrox- ide of aluminum, which in its descent carries the suspended matter with it mechanically. Filtering through charcoal, sand, felt or brick, or through some other porous medium, also deprives water of suspended matter. If a doubtful sample of water must he used for culinary purposes it should ie boiled for half an hour and filtered ; any contaminating matter will thereby probably become destroyed. Peroxide of Hydrogen. We leave now the monoxide of hydrogen, or water, to briefly consider the dioxide or peroxide of hydrogen, and with that will dismiss the compounds of hydrogen. Peroxide of hydrogen is, as the name indicates, a higher oxide than water, having the formula H^O^; by some it is claimed to be a hydrate of oxygen, OH^O. It is a transparent liquid, colorless, of a specific gravity of 1.006 to 1.012. It volatilizes at ordinary temperatures, and when brought in contact with some bodies decomposes with violence. It is odorless, has an acidulous taste, and possesses pronounced bleaching properties. Because it is very unstable, the commercial product has added to it a small proportion of a mineral acid, which renders it some- what more permanent. 48 PHARMACEUTICAL AN'D MEDICAL CHEMISTRY. It may be made from tlie peroxide of barium, BaO^, by- treating with hydrochloric acid: thus, BaO^ + 2H01 = BaOlj -|- HjOj. The BaOlj is precipitated with sulphate of silver, which produces the insoluble salts, silver chloride and barium sulphate, which are removed by decantation. The aqueous solutions of the market are known as the 10 volume and 15-volume products. The 10-volume article, which is official in the U. S. Pharmacopoeia, is known by that name because it contains 3 per cent by weight of the peroxide, which yields ten volumes of active oxygen. The oxygen is the active constituent doing the bleaching for which the solution is mostly used. The quantity of oxygen may be estimated by noting the quantity of acidulated per- manganate of potassium which it decolorizes. A variety known as the 0. P. solution is used in medi- cine and surgery as a powerful antiseptic. Externally it is used as an application to ulcers, and as a dressing to all kinds of wounds. Its value, of course, depends upon the oxygen which it gives off. Nitrogen. History. — Nitrogen was not discovered until 1772, when Butherford isolated a gas which he claimed to be an ele- ment, and which claim was subsequently proved to be true. At first it had two names given it, one, nitrogen, because of its source from nitre ; the other, azote, because it was sup- posed to be poisonous, that word meaning without life. Animals kept in nitrogen for only a brief time would per- ish. We know now that death was not the result of the toxic properties of the nitrogen, but the result of the ab- sence of oxygen, which latter is the life-sustaining princi- ple of the air, PHAEMACEUTICAL AND MEDICAL CHEMISTRY. 49 Occurrence in Nature. — Nitrogen is widely distributed in nature, being most abundant in a free condition in the at- mosphere, of which it constitutes about four-fifths. It plays an important part in the vegetable kingdom, enter- ing into many compounds and forming an essential con- stituent in others. Alkaloids contain it, as do ammonia and nitric acid and all cyanides. It is found, combined with potassium, as Calcutta nitre in India, as an efflores- cence on the earth^s surface. The Chili nitre, or nitrate of sodium, occurs in a like manner on the soil in Chili. Some varieties of coal also contain nitrogen. Functions in Nature. — The chief function of nirtogen in the air is to dilute the more energetic oxygen. It is also es- sential to plants, which imbibe it in the form of ammonia. Properties. — Nitrogen is a colorless, inodorous gas, with- out taste, and from a chemical point of view a very indif- ferent body — to combine it with other bodies we must em- ploy a very circuitous method. It is incombustible and does not support combustion ; a lighted match or taper in- troduced into it is immediately extinguished. It has been liquefied by Cailletet and Pictet and Dewar; its solubility in water is only very slight. It has at times 1 bond, at others 3, 5 and even 7; its atomic weight is 14; molecular weight, 28; symbol, N. Preparation. — It may be prepared in a number of ways, but most commonly it is obtained from the atmosphere by withdrawing or using up the oxygen in it, leaving the nitrogen by itself. A small piece of phosphorus floating in water on a small porcelain cup is ignited and a jar set over it immediately. The phosphorus in burning unites with the oxygen of the air, forming phosphoric oxide, ^fi^. The latter is very 50 PHAKMACEUTICAL AlsTD MEDICAL CHEMISTRY. soluble in water and is soon absorbed, leaving compara- tively pure nitrogen in the jar. Compounds. — With oxygen, nitrogen forms five com- pounds : ISr^O, nitrogen monoxide or hyponitrous oxide. NjOj , nitrogen dioxide. N2O3 , nitrogen trioxide or nitrous oxide. ^fi^ , nitrogen quadroxide or tetroxide. NjOj^ , nitrogen pentoxide or nitric oxide. Of these, three are capable of uniting with water to form acids : N,0 + H,0 == 2HN0, hyponitrous acid. N,03 + H,0 = 2HN0, , nitrous acid. N,0, + H,0 = 2HNO3 , nitric acid. The N^O, sometimes called laughing-gas (also, errone- ously nitrous oxide), is easily prepared by heating ammo- nium nitrate: NH,N03 + heat = 2H,0 + N,0. This is a gas of a sweetish taste, colorless and almost inodorous, having the characteristic property of producing anaesthetic effects upon the system, for which it is employed in dentistry. The N^O, is produced when nitric acid is heated to de- composition or when it acts upon metals, or whenever it acts as an oxidizing agent. Nitric acid is a most power- ful oxidizer; it always resolves itself into water, N^O^ and oxygen in this wise: 2HNO3 + heat = N,0, + 30 + H,0. The oxygen does the oxidizing in combining with other bodies. N^O, is colorless, but when it comes in contact with the oxygen of the air it unites with it to form the tetroxide: N^O, -{- 0^ = N^O^, which is of a reddish color. The NjO^ with water forms nitric acid, as shown above. Two molecules of N^O^ are sometimes looked upon as being PHARMACEUTICAL AND MEDICAL CHEMISTRY. 51 composed of one molecule of N^O and one of 'Nfi^ : 'Nfi -\- N2O3 = 2'Nfi^. A similar view is taken by some of the composition of the N^O^. The N^Og and N^O^ to- gether equal two molecules of N^O^. With hydrogen, nitrogen forms ammonia, NH3 , which is constantly generated in nature during the decomposition of organic matter. The ammonia is also produced by the destructive distillation of organic matter, illustrated in the manufacture of illuminating gas, which is made by the destructive distillation of coal. Ammonia and its salts, as well as the acids of nitrogen, will be considered under other headings. All alkaloids contain nitrogen, as do also cyanogen (ON) and its compounds. These will receive attention in their appropriate places. Many salts containing nitrogen are poisonous; notable exceptions are the nitrates of sodium and potassium. Test for Nitrates. — If to a portion of strong sulphuric acid contained in a test-tube a freshly prepared solution of ferrous sulphate is gradually added so that it forms a layer above the acid, and a portion of a solution of a nitrate is slowly added and the tube gently agitated, a brown zone will form between the acid and the iron solution. Oxygen and Nitrogen as the Atmosphere. The invisible elastic envelope which surrounds the globe as a mantle is the atmosphere, the gaseous matter of which it is constituted being usually distinguished by the name of air. The air possesses no color or taste, nor can it be felt or grasped with the hand, yet, notwithstanding, it is material. Every one has noticed that when a funnel fits very tightly into the neck of a bottle, water poured into 52 PHARMACEUTICAL AI^D MEDICAL CHEMISTRY. it will not run through it into the bottle, the air within the bottle finding no outlet, and being material, according to the general property of matter termed impenetrability (in virtue of which no two bodies can occupy the same space at the same time), prevents the water from entering the bottle. When the funnel is slightly raised the water rushes into the bottle, the air being displaced at the same time and rushing out of the bottle. Air has weight like all other forms of matter; a globe when weighed has a greater gravity than when the air is exhausted from it. To exhaust a vessel, a globe, e.g., of air, an instrument called an air pump is employed, which removes the air more or less thoroughly, causing a vacuum, though it is almost impossible to create an absolute vacuum. The difference in weight of the flask or globe before and after exhausting the air, the volume of its capacity taken into consideration, will show the weight of the air which the flask or globe will hold. It is thus ascertained that a cubic foot of air weighs about 538 grains; a room 40 feet square and 18 feet high contains about a ton of air. Air compared with hydrogen has a specificgravity of 14.4; water is about 825 times heavier than air. It is supposed that the air extends about 50 miles upward, although some claim only 10 miles, and others even 200 miles; more recent ex- periments favor the first-mentioned supposition. It is ob- vious that this tremendous ocean of air, at the bottom of which we live, must exert a vast pressure upon the surface of the earth. This pressure amounts to 15 pounds upon every square inch of the earth^s surface; it is not only directed down- ward, but in all directions — upward, sideward, etc. The weisfht of the air is not the same at all times, as it be- PHARMACEUTICAL AND MEDICAL CHEMISTEY. 53 comes condensed or rarified by atmospheric changes in- duced by winds, storms, etc. ; it may be conceived to be moved by tides which sweep over the earth, and with these movements the pressure or weight changes, though never very much. The variations in the pressure may be meas- ured, and the instrument by which we can record these changes is called a harometer. To make this instrument a glass tube about 33 or 34 inches in length, and closed at one end, is filled with mercury, the open end closed with one finger and inverted into a vessel containing mercury. The finger should not be released until the open end is fully under the mercury in the vessel. The mercury in the tube will sink until the column is about 30 inches from the surface of the liquid in the vessel. The weight of the air pressing upon the mercury in the vessel supports the mercury column at the given height — 30 inches. One cubic inch of mercury weighs ^-pound, and if the tube were 1 inch square the 30 inches in height would weigh 15 pounds. It is thus that it was ascertained that the pressure of the air is 15 pounds upon every square inch, for it requires a pressure of 15 pounds to support a column of mercury weighing 15 pounds. The column of mercury will rise or fall according to the pressure of the air; when the air is rare the barometer is low, when the air is condensed and heavy the barometer registers higher. This atmospheric pressure is often spoken of simply as " atmosphere ; ^^ two "atmospheres^^ would indicate a pressure of 30 pounds upon a square inch, three " atmospheres ^"^ one of 45 pounds, etc. The pressure decreases as the height increases, and increases as the distance downward from the surface of the earth increases. That is because as we ascend, the bulk of air above us becomes less, and as we descend, the bulk, and consequently also the weight, becomes greater. 54 PHARMACEUTICAL ANB MEDICAL CHEMISTBY. The Chomical Constituents of the Air. The atmosphere is a mixture of a number of gases, among which nitrogen and oxygen are the most abundant. Its composition by volume is computed to be : Oxygen 20.81 Nitrogen 77.95 Carbonic acid gas 0.04 Aqueous vapor 1.20 100.00 Nitric acid. Ammonia. Sulphuretted hydrogen. Carburetted hydrogen. Sulphurous acid. Organic vapors. Traces, The oxygen is the animal-life-sustaining principle of the air, while the nitrogen dilutes it so that animals can thrive in it — in pure oxygen we could not live. The oxy- gen oxidizes the refuse matter collected by the blood, in the lungs, converting much of it into carbonic acid gas, which is exhaled, and therefore is always present in the atmosphere. The composition of the air going into and coming out of the lungs is this : Going into the Lungs. Oxygen 20.00 Nitrogen 79.96 Carbonic acid gas 0.04 100.00 Coming out of the Lungs. Oxygen 16.00 Nitrogen 79.96 Carbonic acid gas 4.04 100.00 It will be seen that 4 per cent, of the oxygen is converted into carbonic acid gas, so that air once breathed contains 100 times more of the gas than pure air, and since the car- bonic acid gas is poisonous if inhaled in quantities of 4 per cent., it becomes apparent how essential it is to have good ventilation in our houses. Air as exhaled is wholly unfit and dangerous to breathe again. The air in houses does not contain carbonic acid gas from this source only — lamps PHARMACEUTICAL AN^D MEDICAL CHEMISTRY. 55 and gas when burning produce a considerable quantity, a gas flame, for instance, as much as five or six persons. It would seem that the quantity of this gas in the at- mosphere (0.04) would gradually and constantly increase, but Nature, in its wise economy, provides that this gas, which is noxious to animal life, should serve an important role in the sustenance of the vegetable kingdom, in that it furnishes the greater bulk of the food of all plants. Plants draw their nourishment from two sources — from the soil, by absorption of moisture and mineral matter, and from the atmosphere, by breathing the carbonic acid gas, retain- ing or -fixing the carbon in their structure and exhaling the oxygen. The refuse of one kingdom is the essential life-principle of the other — animals breathe oxygen and produce carbonic acid gas ; the plant breathes this carbonic acid gas, resolves it into carbon, which it retains, and oxygen, which it gives out again — a beautiful natural reciprocity. The other constituents in the air are of minor impor- tance, and their proportion is never constant. Small pro- portions of nitric acid and ammonia are always present, while sulphurous acid and sulphuretted hydrogen are only found in the air of crowded cities or near manufactories, etc. Ammonia may sometimes be detected in rain water, which washes it out of the air, while nitric acid is usually found after thunderstorms. The latter is thought to be formed by electricity, every flash of lightning causing the oxygen and nitrogen in the air to combine with some of the watery vapor to form the acid. Such constituents of the air as the odorous emana- tions from flowers, the various bacteria, saline particles 56 PHARMACEUTICAL AKD MEDICAL CHEMISTRT. from the spray of the ocean, dust, etc., are only found at times, and are restricted to localities. The moisture in the air varies much, sometimes being present in as small a quantity as |- per cent, or even less, while at other times as much as 2 per cent, is present, when the air is wholly satu- rated. We feel so uncomfortable on warm, close days be- cause the air is so saturated with aqueous vapor that the exhalations from our bodies (perspiration) cannot be taken up by it and consequently cling to our bodies. Carbon. Occurrence in Nature. — Carbon occurs in nature as coal, graphite, plumbago, diamond, etc. The diamond and graphite are crystallized forms, while all, or most all, other forms are amorphous. In combination it is the essential constituent of all organic matter; indeed, the chemical study of organic bodies is now termed "the chemistry of the carbon compounds,^^ while all organic bodies are in- cluded in the general term carhon compounds. Carbon is also a constituent of carbonic acid gas; all carbonates con- tain it, as well as all cyanides. AVe are familiar with car- bon also as lampblack, bone-black, charcoal, gas carbon, coke, soot, etc. AYe thus see that this element occurs in several forms, the three principal ones being the diamond, graphite and coal. This property of existing in two or more conditions or forms, which are distinct in their physical or chemical relations, is called allotropism, and the forms allotropic forms. There is no explanation for the existence of these conditions. AVhy the diamond occurs crystallized in octa- hedral (eight-sided) and other related forms in a state of extreme hardness, while blacklead occurs in hexagonal PHARMACEUTICAL AN^D MEDICAL CHEMISTRY. 57 (six-sided) forms, with very little hardness, and lampblack with no hardness at all and devoid of crystalline shape, we are at a loss to explain. Some chemists claim that these allotropic forms represent the passive and active states of carbon. (Ozone is an active state of oxygen and distinct from the ordinary oxygen, which is the element in its passive state.) Properties. — Carbon in any form is insoluble, not fu- sible nor volatile, but combustible, forming carbon mon- oxide or the dioxide usually. Chemically it combines with many of the non-metals, but principally with hydrogen, with which it forms that important class of bodies known as hydrocarbons; with oxygen to form two oxides, CO and CO2, and with nitrogen in the organic kingdom. With hydrogen alone carbon forms hydrocarbons, but with hydrogen and oxygen, and the latter two in the pro- portion to form water, it forms carbohydrates. CH^, marsh gas, is a hydrocarbon. Cj^H^jO^, cane sugar, is a carbohydrate. The product of the combustion of carbon is always carbonic acid gas, CO^, at times accompanied with carbon monoxide, CO. The diamond, the most precious of the gems, is the purest form of carbon. Its hardness and refractory power are characteristic and give it its value; it is one of the hardest substances known, and when properly cut refracts and resolves white light into the primary colors like no other body. When heated intensely it burns, producing CO 2, but resists the action of any known chemical. Plumbago, or graphite, is an almost pure carbon, though most specimens contain a small proportion of iron. We are all familiar with this form of carbon in lead pencils, the graphite being erroneously called lead at times. 58 PHARMACEUTICAL AND MEDICAL CHEMISTRY. Lampblack is the soot produced when oil or some kinds of resin burn with an insufficient quantity of oxygen. It contains unchanged oil frequently. Charcoal is produced when wood is incompletely burned, usually by a procees known as destructive distilla- tion, as in the preparation of acetic acid. It may be pre- pared also by the smothered combustion of piles of wood partially covered with earth. This kind of charcoal is called wood charcoal, to distinguish it from animal charcoal, which is the residue obtained on heating bones to a red- heat without access of air. This residue contains, besides carbon, phosphate, of calcium, which when removed with hydrochloric acid leaves the imrified animal charcoal. This is a very valuable substance, because of its property of removing coloring matter from solutions of organic matter. It plays an important part in the refining of sugar. The crude juice from the sugar-cane yields upon evaporation a very dark-brown sugar, whose color is due to natural color- ing matter. The white granular or block sugar is the same devoid of the coloring matter, which is removed by filtering the solution of brown sugar or the crude cane-juice through animal charcoal contained in large percolators. The manufacturing chemist employs animal charcoal for similar purposes, and for removing certain other bodies from solution. Nearly all varieties of charcoal possess this property, but none so much as the animal charcoal. Charcoal prepared from dense wood has the property of condensing gases and vapors; it will absorb 90 volumes of ammonia gases, while of hydrogen it takes up about twice its own volume. In thus absorbing the gas the charcoal probably causes the gases to liquefy. Compounds of Carbon with Hydrogen. — Carbon and hy- PHARMACEUTICAL AND MEDICAL CHEMISTRY. 59 drogen form compounds which are the starting points in organic chemistry. From these hydro cartons a vast number of compounds are derived, either by adding, taking away or substituting other atoms or groups of atoms; indeed, the complete study of the hydrocarbons, their com- pounds and substitution-derivatives, constitutes the entire science of organic chemistry. These bodies are obtained in nature usually by the decomposition of more complex or- ganic substances, but they may be made by direct combina- tion, in many cases, in the laboratory. Acetylene, OJS.^, for instance, may be obtained by directly combining the elements by passing a stream of hydrogen through a tube in which a current of electricity is passing between two carbon poles. Methane, or marsh gas, CH^, is another hydrocarbon of simple construction, and is produced when organic matter decays under water, as it does in marshes, hence the name. It, too, is the beginning of a long series of carbon compounds, and with the acetylene and ethylene or olefiant gas, is an important factor. Illuminating Gas. — The manufacture of coal or illuminat- ing gas is an industry of importance. The process is a simple one, yet in practice requires considerable skill. Coal is subjected to destructive distillation, which produces a variety of gases and other products, among which is a considerable quantity of ammonia, from the nitrogen which is always present in coal. The distillation of the coal goes on in large cast-iron retorts maintained at a red heat in a furnace. The gases and all the volatile products are con- ducted upward into and through a long horizontal pipe, containing water and called a hydraulic main. From there the gas passes into an apparatus which serves the 60 PHARMACEUTICAL AND MEDICAL CHEMISTRY. purpose of a refrigerator, consisting of a series of vessels filled with water and so arranged that the gas must pass through a considerable quantity of water. The pro- cedure not only cools the gas but causes the condensation of tar and ammonia. Much tar is deposited in the hy- draulic main, from where it runs into a reservoir known as the tar-ivell, but the gas being still very hot not all the tar condenses, and some passes over, to be deposited in the refrigerator with the ammonia. The process of purification is continued by causing the stream of gas to pass through a chamber called the scruhber, which is filled with loose material, or anything that gives space. Here much sus- pended matter is removed. Next the gas is washed by being made to pass through an apparatus where it comes in contact with a number of sprays of water. The gas still contains sulphuretted hydrogen, carbonic acid gas and disulphide of carbon, which are removed in the purifiers. The latter are very large tanks filled with lime. The im- purities mix chemically with the lime and are retained. The gas is finally stored in the large gas tanks, with the appearance of which we are all familiar, and from which it is supplied to the consumer. Illuminating gas varies much in its composition, judging from its illuminating powers. If properly purified it con- tains methane, CH^; ethylene, CjHj acetylene, C^H^, hydrogen, carbon monoxide, CO; free nitrogen, a little disulphide of carbon and a small quantity of volatile liquid hydrocarbons. Compounds of Carbon with Hydrogen and Oxygen. — The carlohydrates, as already observed, are a class of com- pounds containing carbon ^ united with hydrogen and oxy- gen in the proportion to form water; there are usually six PHARMACEUTICAL AND MEDICAL CHEMISTRY. 61 carbon atoms or a multiple of six present. There are three groups of these compounds : the glucoses, represented by grape sugar, fruit sugar, and all having the composi- tion OgHj^Og; the saccharoses, of which cane sugar, milk sugar and maltose are examples, having the composition OjjH^^Oj,, and finally the amyloses (starches), O^^fi^, with starch, dextrin and cellulose as representatives. It will be seen that the hydrogen and oxygen in each case are in the proportion to form water — in cane sugar, for in- stance the Hj^Og are equal to 6 H^O — i.e., six molecules of water. Cellulose, of which ordinary absorbent cotton is a good example, has a formula represented by a multiple of the six carbon atoms usually present in the carbohydrates; its formula is that of amylose or starch multiplied by three — O^gHgoOj,. The carbohydrates, like the hydrocarbons, are an exceedingly interesting and useful class of compounds, but cannot be considered here. Alkaloids and Glucosides. — Carbon united with hydro- gen and nitrogen alone, or with these and oxygen, forms the two series of compounds known as alkaloids and glu- cosides. These, too, are relegated to organic chemistry and cannot be dwelt upon here. Compounds with Oxygen. — There are two compounds of oxygen and carbon: CO, carbon monoxide, and CO,, car- bon dioxide. Carbok Monoxide is a combustible gas, producing carbon dioxide when it burns : 2C0 -|- 0, = 2CO2. I^s flame is a beautiful pale blue, which may be viewed in any coal stove when the coal has just begun to burn. The gas is without color, almost without odor, and is very poison- ous. It is produced abundantly, together with carbon dioxide, when charcoal burns. It rapidly produces in- 62 PHAEMACEUTICAL AND MEDICAL CHEMISTRY. sensibility and death when inhaled. When oxalic acid is heated with five or six times as much sulphuric acid, car- bon monoxide and dioxide are formed, from which mix- ture the dioxide may be removed by passing through a strong solution of caustic potassa. The dioxide unites with the potassa to form potassium carbonate, while the monoxide passes unchanged. Another method for the production of the monoxide is the heating of potassium ferrocyanide with ten times its weight of sulphuric acid. An abundance of the gas in a pure state is thus generated. Extreme care must be observed not to inhale this gas. Carbois' Dioxide, sometimes erroneously termed car- bonic acid, is always produced when anything containing carbon burns with a sufficient supply of oxygen. When the supply of oxygen is insufficient the monoxide is often formed. In these two gases we have a good illustration of the law of multiple proportions referred to in the para- graphs on chemical philosophy. If carbon, whose atomic weight is 12, combines chemically with oxygen, and there is only a limited supply of the latter, the combination takes place between 12 of the carbon and 16 of the oxygen, forming 28 of CO, but if the oxygen is plentiful the car- bon unites not with once the atomic weight of oxygen, 16, but with a multiple of 16 — namely, 32, producing 44 of CO^; that is, while the proportion of carbon is constant, that of oxygen increases, in the case of 00^, in a multiple proportion. Comhustion is ordinarily oxidation — that is, the union, chemically, of a body with oxygen, with the production of heat and flame. That body may be hydro- gen, sulphur or phosphorus, etc., but usually it is car- bon in some form or other. The burning of coal, wood, gas or oil is simply the union of the carbon in those bodies PHARMACEUTICAL AND MEDICAL CHEMISTRY. 63 with the oxygen in the air, producing carbon dioxide. The blood is continually purified in our lungs by the car- bon in the refuse matter collected by the 'blood uniting with the oxygen brought into the lungs as air. For experimental purposes the gas is easily prepared by decomposing any carbonate (that of sodium is cheap) with an acid. On a larger scale, as in the making of the car- bonated waters, marble, the carbonate of calcium, is de- composed with acid, hydrochloric usually, or sulphuric : Hydrochloric Calcium Carbon Marble. Acid. Chloride. Water. Dioxide. CaC03 + 2HC1 = CaOl, -f H,0 + CO, Any carbonate when treated with one of the strong acids yields free CO,. This fact is taken advantage of in test' ing for carbonates. Whenever an eilervescence (evolution of gas) takes place when a body not a metal is treated with an acid, it is safe to assume that the body was a carbonate. Carbon dioxide is a colorless gas, with an agreeable pungent taste and odor. It is poisonous to animal life, as already observed when discoursing on the atmosphere. It is incombustible and does not support combustion — a lighted match or taper plunged into the gas is immedi- ately extinguished. In this respect and in others it is not unlike nitrogen, but may be distinguished from it by its rapid absorption by solution of caustic potassa or lime- water. The latter with the gas becomes turbid, owing to the formation of insoluble carbonate of calcium. The gas can thus be detected in the breath by blowing through a tube into lime-water. Water dissolves about its own bulk of CO,, but many times its volume if under pressure. Soda-water is common water charged with carbon dioxide under pressure. The 64 PHARMACEUTICAL AND MEDICAL CHEMISTRY. soda-water can be drawn through pipes upward for a dis- tance, because the gas, owing to its expansive force and pressure, tries to get away from its confinement and carries the water with it. Effervescing wines and sparkling min- eral waters owe their effervescing qualities to carbon di- oxide. In the former it is produced during the process of fermentation, when the grape juice changes its sugar into alcohol; in the latter it is present through the absorption of the gas produced in nature, usually in the earth near springs. It is always a product oi fermentation diu.^ putre- faction. These latter terms are synonymous, in a sense — they both mean the decomposition of organic matter. When the products of the decomposition are useful the process is termed fermentation, as in the formation of alcohol by the decomposition (natural decomposition) of grain; but when the products are useless and offensive the process is called putrefaction. In many of the mineral waters carbon dioxide plays an important part, as has been mentioned in the chapter on water, to which the student is again referred. Carbonic acid gas, as the gas is often correctly termed, can be liquefied; it requires for the purpose a pressure of 577 pounds to the square inch. When liquefied it is color- less, lighter than water and, when unconfined, four times more expansive than air. Because of this and its power to extinguish fire it may be found in many places kept in strong glass flasks hermetically sealed, to be used in case of fire. The flask breaks when thrown into a burning mass; the liquid at once volatilizes, extinguishing all flame it comes in contact with. Care must be taken that no persons or animals are near. The Carbonates form a very large and important PHARMACEUTICAL AND MEDICAL CHEMISTRY. 65 series of salts, many of which occur abundantly in nature. Carbonate of calcium is found in nature in many forms, most largely as marble, limestone and chalk. The shells of all crustaceous animals, such as oysters, clams, lobsters, etc., are wholly composed of calcium carbonate. The car- bonate of magnesium also occurs very abundantly. The carbonates may be represented as containing the oxide of a metal united with CO2. Chalk, for instance, CaCOg, is CaO, oxide of calcium, and CO^ ; carbonate of magnesium, MgCOg, is the oxide, MgO, and CO,; white lead, PbCO^, is the oxide of lead, PbO, and CO,. Carbokic Acid, H^COg, may be looked upon as water, H^O, and CO,. The compound is not stable and always resolves itself into water and CO,. Attention should here be called to an error which is too often made. CO, is car- hon dioxide, or carbonic acid gas, and not carlonic acid, as it is so frequently called. There can be no acid without hydrogen, and carlonic acid is CO, with water, H,0, which furnishes the hydrogen. Carbon with the Halogens. — There are a number of compounds of carbon and chlorine known: C,C1„ C,C1^, C,Clg, etc., and a similar group with iodine and bromine. Carbon with Nitrogen forms cyanogen, CN, which is a colorless gas of a pungent, peculiar odor resembling some- what that of hydrocyanic acid. Cyanogen unites with hydrogen to form the most poisonous compound there is, hydrocyanic acid, sometimes called prussic acid. With metals it forms compounds called cyanides. Cyanogen is a good illustration of what is meant by a compound radical ; it is a group of elements, carbon and nitrogen, which com- bines with elementary bodies, and is capable of passing from one state of combination to another just as though 6Q PHAKMACEUTICAL AND MEDICAL CHEMISTRY. it were a single element. Ammonium, NH^, is analogous to cyanogen in this respect, except that it acts as a base or like the metals, while cyanogen is related to the non- metals in the same sense. Carbon with Sulphur forms, like carbon and oxygen, two compounds, the monosulphide, OS, and the disulphide, OSj. The disulphide is of some importance in that it is a good solvent for some bodies which are ordinarily insolu- ble. It has a very offensive, repulsive odor as found in the market, but when pure is almost odorless. Sulphur is easily dissolved by it, and is again deposited in crystals upon evaporation of the disulphide. Its use is mostly in the arts, though to some extent it is utilized in extracting oil from seeds. It dissolves or extracts the oil, leaving it again upon evaporation or distillation. The Halogens. The four elements known as the halogens (salt pro- ducers, so called because they exist in sea-water) are chlo- rine, bromine, iodine and fluorine. We will consider them in the order named and begin with Chlorine. Chlorine is one of the natural group of elements called halogens, which not only have a common source, but re- semble each other in a marked degree in all their chemical relations. The similarity in chemical behavior is especially noticeable between chlorine, bromine, and iodine; fluorine, because chemists have not been able to isolate it in any quantities large enough to experiment with, has not been so thoroughly studied, but its behavior in combination is very like that of the other halogens in many respects. PHARMACEUTICAL AND MEDICAL CHEMISTRY. 67 Occurrence in Nature. — The halogens occur chiefly in the sea, usually in combination with sodium, potassium, magnesium and calcium. Chlorine is the most abundant, and is found mainly as the chloride of sodium — common salt — in the ocean, as brines, and in mines as solid crystal- line masses. Some springs contain it; the St. Catherine's water contains it in combination with magnesium. As the chloride of sodium it is universally distributed in minute quantities; the tissues of plants and animals contain it as an essential constituent. History. — The Swedish chemist, Scheele, who also dis- covered oxygen, discovered chlorine. While experiment- ing with hydrochloric acid he brought it while hot in contact with hraunstein, brownstone, dioxide of manga- nese, when he noted an irritating, suffocating gas coming off, which he and others subsequently proved to be an ele- ment; this also was in 1774. It is a peculiar coincidence that oxygen should have been discovered at about the same time by two men, Priestley and Scheele, distant from one another and without knowledge of each other, but it is more so that one body — dioxide of manganese — should have served in the discovery of two elements, for Scheele not only discovered oxygen by heating the dioxide, when oxygen was evolved, but chlorine as well by treating the dioxide with hydrochloric acid. In the first instance the element, oxygen, was a constituent of that from which it came, MnO^ , but in the case of chlorine the dioxide was only an agent for the liberation of chlorine from hydro- chloric acid, and did not furnish the chlorine itself. Preparation. — The accidental method which furnished Scheele's chlorine is to-day yet employed as the simplest, though there are many others. Manganese dioxide, MnO^, 68 PHARMACEUTICAL Ai^D MEDICAL CHEMISTRY. is introduced into a flask provided with a safety-tube for pouring in the acid and a bent tube for conveying the gas to a receiver. A small portion of hydrochloric acid is poured through the safety-funnel tube into the flask and thoroughly shaken, so that all of the manganese becomes wetted; then more acid is added and gentle heat applied, when the evolution of the gas ensues at once, and may be collected as is any other gas. The equation illustrative of this reaction is: MnO, + 4HC1 = MnCl, -f 2H,0 + CI, Dioxide of Hydrochloric Chloride of Water. Chlorine, manganese. acid. manganese. Instead of using hydrochloric acid, sulphuric acid and common salt are sometimes employed — i.e., the dioxide is mixed with common salt, to which mixture the sulphuric acid is added. The common salt and sulphuric acid react upon each other, producing hydrochloric acid : 2 NaOl + H^SO, = Na.SO, + 2 HCl. The HCl thus produced in the operation is then acted upon by the manganese dioxide with the result above illustrated. Chlorine gas, thus produced and passed into water, con- stitutes the aqua chlori of the pharmacopoeia, which con- tains 0.4 per cent, of gas. It does not keep well, produc- ing hydrochloric acid through the decomposition of the water by the union of the chlorine with its hydrogen. Keeping in dark places prevents this change to an extent, but the water is never reliable if kept for any length of time. Properties. — In chemical energy chlorine surpasses many of the elements, even oxygen in some cases. It has a greenish color which is characteristic, a peculiar suffocating odor, and when inhaled produces distressing irritation of PHARMACEUTICAL Ai^D MEDICAL CHEMISTRY. 69 the mucous membranes of the throat and lungs. Some claim that if respired in very minute quantities it is bene- ficial in pulmonary troubles. A pressure of four atmo- spheres liquefies the gas to a transparent yellow liquid which it is difficult to freeze into solid condition. That chlorine maintains combustion may be shown by dropping pow- dered antimony, arsenic or phosphorus into it; the chlo- rides of these will be formed almost immediately, with the production of heat and fiame. Burning is ordinarily oxi- dation ; in this case it is clilorination. An interesting ex- periment may be made by saturating a piece of paper with oil of turpentine and plunging it carefully and dexterously into a vesssel containing chlorine. A dense black smoke is emitted which usually turns into a flame from the rapid decomposition of the turpentine. The atomic weight of chlorine is 35.4, its density the same, and its specific gravity compared to air 2.45. It has but little attraction for oxygen, but all the more for hydrogen and the metals, with which it forms chlorides. Wood or wax will burn in chlorine with a dull red flame, burning the hydrogen only, producing hydrochloric acid. The bleaching power of chlorine is its most characteristic property; organic coloring principles which resist the bleaching action of other bodies are almost instantly de- stroyed by it. Indigo, which will not change its color with strong sulphuric acid, has its color discharged by chlorine. Whenever chlorine bleaches it does so not by hiding, so to say, the color, as sulphur dioxide does, but by completely destroying it, so that it cannot be restored. Water must be present for chlorine to act as a bleach- ing agent, as the gas in a perfectly dry condition is devoid of any bleaching qualities; it will not even affect 70 PHARMACEUTICAL Ai^D MEDICAL CHEMISTRY. litmus when dry. In pharmacy and in the arts and indus- tries chlorine is used largely in the form of Ueacliing- foivder, which contains 35 per cent, of available gas. It is employed principally for bleaching cotton and linen goods. Chlorine is one of the most thorough and potent disinfect- ants, and for this purpose is usually employed to form the bleaching-powder, or chloride of lime, as it is errone- ously termed — chlorinated lime is the proper term. When chlorinated line is mixed with water in a flat vessel it decom- poses slowly through the action of the carbonic acid gas in the air, setting the chlorine free. Mixing a little hydro- chloric acid with it serves to disengage the gas more rapidly. It is not prudent to use the gas for disinfecting purposes, its use by inexperienced persons being fraught with danger. Compounds Containing Chlorine. — With oxygen chlorine cannot be united directly, all the known combinations be- ing produced indirectly. All the oxides and correspond- ing acids decompose very easily, sometimes with violent explosion, for which reason many of their compounds are employed in making explosives. The oxides and acids ob- tained from them by their union with water are the fol- lowing : Cl^O, Jit/pochlorotis oxide, + H^O = 2HC10, Jiypochlor- ous acid. CI2O3, chlorous oxide, -\- Kfi = 2IIC102,- chlorous acid. ClgO^, tetroxide. Acid not known. CljO^, chlorzc oxide, + ^fi = 2HCIO3, chloric acid. Cl^O,, ^;erchlor2c oxide, -f H„0 — 2HC10^, jjerchloric acid. In viewing the composition of these oxides it will be seen that the quantity of chlorine is constant in each, the quantity of oxygen increasing, which illustrates again the PHARMACEUTICAL AND MEDICAL CHEMISTRY. 71 law of multiple proportions. It not only illustrates this law, it teaches also A Lesson in Nomenclature^ i.e., the naming of compounds. Here we have a series of combinations, all containing the two elements, but each containing one element in different proportion from that in another. Now, it is this difference, in the quantity of oxygen in this case, that enables chemists to apply a defi- nite specific name to each combination. The terms mono, di, tri, tetra and pentoxide would be names for combina- tions containing, respectively, one, two, three, four and five atoms of oxygen. Besides these numerical terms the chemist employs others which are relative ones, the rela- tion starting from some one combination. These relative terms are the true chemical names. To the highest form of oxidation is usually given a name, to which the names of the others bear a relation. In this case the Cl^O^ was once thought to be the highest form of oxidation of chlo- rine, and was called chlor^c oxide, the ic always meaning higJiest, The Cl^Og was the next highest, or the one next below the highest, and it was termed chloro?^s oxide, the o^cs meaning loiver. There being also a Cl^O, that is, with the Cl^Oj, two chloro2^s oxides, another prefix had to be employed to show that the 01^0 was a combination of the ous kind, though lower than one already called chlorous. The prefix hypo was called into requisition, which means heneath, so that the hypoohlovous oxide 01^0 is a combina- tion lower than the chloroz^s oxide. For the CI2O, a name had to be chosen which would indicate that it was a union of chlorine and oxygen with even more oxygen in 72 PHARMACEUTICAL AND MEDICAL CHEMISTRY. it than the one termed chloric oxide. The prefix per means above, so that the word pe^^oxide means above the highest oxide. (Intrinsically the Cl^O, would be the chloric oxide, etc.) What has been said of the names of the com- binations of oxygen and chlorine is not confined to these, but the principles are qenerally ajjplicahle in chemical nomenclature. With hydrogen, and with hydrogen and oxygen, chlorine forms acids, which may be directly derived from the above oxides by adding water, except in the case of hydrochloric acid, as can be seen above. Most oxides of the non-metals form acids with water, the hydrogen in the water forming the base of the acid, and without which no acid can exist. It will be seen that with loater the various non-metallic oxides form acids which have the same names as the oxides. Knowing, therefore, the name of an oxide, we can tell the name of its corresponding acid, and vice versa. The cor- i^esponding acid of an oxide is what is obtained when water is added to that acid; for instance, the acid corres- ponding to the chlorous oxide, Cl^Og, is chlorous acid : 01,03 + H,0 = 2H010 The names of the acids furnish us names for the salts which are formed from the acids. Salts are generally derived by replacing the hydrogen in acids by a metal. Thus, if we replace the H in hydrochloric acid, HOI, with sodium, Na, we get NaOl, which is a salt; so by putting an atom of magnesium, Mg, in place of the H in sulphuric acid, H.SO,, we get MgSO,, also a salt. Let us now make salts from all of the chlorine acids. The only acid not containing oxygen in this series is hydro- PHARMACEUTICAL AND MEDICAL CHEMISTRY. 73 chloric acid, which can be made by direct union of H and 01. If in the following acids the The following-named salts will be hydrogen is replaced by produced : sodium, Hydrochloric acid, HCl. . . | ^^^M^^f '''^''''^' ""' '''^''' \ ^^^^ Hypochlorous " HCIO. j ^^g^^?!;^^^^ Chlorous - HCIO. ] ™MonYf! '^^'""':.^^^ Chloric " HClOa ] ^'^chlom?/ ^''^''''^' ""' ^''^''' \ ^^^^^' T>^««ui^«i^ (f rrmrk \ Pcrchlortt^e of sodlum, or } ^^ ^.„^ Perchloric HCIO. -j god ic perchlora^.. .......[ ^^^^^^ It will be seen from this that acids having the prefix hydro and the suffix ic make salts ending in ide : hydrochloric acid yields a chlor^V?e of any metal. The acid whose name ends in ous and has hypo for prefix yields salts called hypo- chloTites; the ous acids yield ite salts : chlorous acid gives chlor^^e of a metal, sodium, in this illustration; the ic acids yield salts whose names end in ate : chloric acid yields chlovates; acids having names with per for prefix and ic for suffix yield salts whose names begin with per and end in ate : perchloric acid yields ^erchlora^e^, it being under- stood that in each case the hydrogen of the acid is replaced by a metal. Experiments. — Before beginning the discourse upon the uses of chlorine in pharmacy, directly and indirectly, its importance warrants the giving of a little time to experi- menting, especially with a view of illustrating more fully its properties, chemical and physical. Besides those given before, the following experiments may be made by the student. He is advised to experiment whenever practica- ble, and to record his observations for future reference, and always to be careful in his experiments. t4 PHAEMACEUTICAL AND MEDICAL CHEMISTKY. 1. Illustrating Diffusion of Gases. — If chlorine gas be made, as before directed, by displacing water in a flask and the flask exposed to the atmosphere, it will take a long time for the green color of the gas to disappear; the dis- appearance of the color naturally indicates the disappear- ance of the gas. If another flask containing chlorine gas be inverted, the flasks being in both instances without stoppers, it will require only a very short time for the chlorine to mix with the atmosphere and the flask to become fllled with air. This phenomenon is due to the fact that chlorine is 2.5 times heavier than air. If it were not for a natural law, the laio of diffusion of gases, the chlorine in the first flask would remain there indefinitely, being much heavier than air, for it must be remembered that gases, like liquids, when carefully mixed, arrange themselves in layers accord- ing to their densities. The layers of liquids (in case of miscible liquids) when once arranged remain so perma- nently; for instance, a test-tube containing sulphuric acid may have a layer of water poured in without disturb- ing the sulphuric acid — i.e., the acid and water form two layers which remain permanent if not disturbed by some external force. The same is true of gases, so far as their arrangement according to their density or heaviness is concerned, at first, but the layers are not permanent. Notwithstanding the different densities of gases, they will diffuse or intermingle with each other in admixture until the mixture will have attained a mean density. Where there is no limit by a containing vessel, as in the atmo- sphere, the diffusion practically goes on indefinitely. (See physical properties of hydrogen on pages 29 and 30.) PHARMACEUTICAL AND MEDICAL CHEMISTRY. 75 2. Illustratiitg Bleaching Properties. — Make chlo- rine gas as before, and pass it through a tube or bottle con- taining chloride of calcium, and conduct it to the bottom of the bottle which is to contain it. The bottle will be- come filled with chlorine, which disi^laces the air. The object of passing the gas through the calcium salt is to remove any watery vapors with which it may be mixed, to obtain a thoroughly ^r?/.gas. The chloride of calcium has a great affinity for water, and absorb sit from its mixture with a gas. A piece of dry litmus-paper or a dry red rose plunged into this dry chlorine gas will not have its color affected. Moisten the litmus-paper or the rose, and again introduce into the chlorine. The color begins to dis- charge, and very soon the paper or rose will be perfectly white. This illustrates that chlorine will not bleach unless water is present. A little chlorine -water poured into ink or red wine or indigo solution causes each of the liquids to lose its color. All colors derived either from the animal or vegetable king- dom are lileaclied or destroyed hy chlorine. This property makes chlorine a most important agent for bleaching cotton, linen, paper and many other materials. It renders these bodies perfectly white in a few hours, while the old method of bleaching by laying the goods on the grass in sunshine required weeks, and sometimes months. 3. Illustrating Disinfecting and Deodorizing Properties. — If chlorine-water is applied to decaying and badly smelling substances (stagnant water, rotten eggs, etc.) the bad odor vanishes very quickly. It not only decomposes colors, but also the products formed during decay, and which produce nauseous odors. Morbific matter, disease germs, miasms, which, by being 76 PHARMACEUTICAL Ai^D MEDICAL CHEMISTRY. diffused in the air or attached to beds, clothes or walls may communicate disease, are acted upon in a similar manner. Chlorine is therefore a deodorizer and powerful disinfectant, purifying infected atmospheres and all kinds of morbid matter, and arresting or checking the decay of organic substances. 4. Illustrating- the Affin"ity of Chloriis^e for Htdrogek. — Fill a small flask with chlorine-water and invert into a vessel containing water, and put away into the dark; there will be no change and the chlorine water will keep for a tolerable length of time; but if the flask be ex- posed to sunlight decomposition will soon ensue, with the formation of a gas which collects in the upper part of the flask. After a few days the water will have lost all of its chlorine odor and will have acquired a sour taste, and in- stead of bleaching litmus paper will turn it red, showing acid reaction. The gas collected in the upper part of the flask will be found to inflame a glowing taper and exhibit other properties which establish its identity as oxygen; the acid reaction is due to the presence of hydrochloric acid. We began with chlorine and the elements of water, hy- drogen and oxygen. These, later on, are yet present, but not in the original condition or combination — the chlorine being now not free or uncombined, as it at first was, but in combination with the hydrogen as hydrochloric acid. In other words, chlorine has much chemical affinity, so much, in this case, that it decomposes water, under the in- fluence of sunlight, and unites with the hydrogen, setting free the oxygen, thus: 2C1, + 2H,0 = 4HC1 + 0,. When the water is decomposed the chlorine has the choice of uniting with oxygen or with hydrogen, but it selects the latter, affording an example of what is termed 8imi:)le elec- PHARMACEUTICAL AND MEDICAL CHEMISTRY. 77 tive affinity. Now, this very chemical affinity of chlorine for hydrogen explains its bleaching and disinfecting power. When chlorine bleaches it simply causes the decomposition of the coloring matter in order to unite with the hydrogen which is present in all animal and vegetable bodies. By this abstraction of the hydrogen a rearrangement of mole- cules to form other combinations is necessary, causing the coloring matter to become colorless. 5. Illustrating the Affinity of Chlorine for Bases. — Make a solution of iodide of potassium or of the iodide of any base, and add freshly-made chlorine-water; the iodine will be set free and the chlorine take its place, making a chloride of potassium. Treat a solution of any bromide with culorine-water or any form of free chlorine — the bromine becomes liberated and may be recognized by its odor and color. This shows the chlorine to have more affinity for the base than the bromine or iodine has, which it replaces in all their combinations. 6. Showing the Solvent Power, Chemically, of Chlorine. — Into chlorine-water put a leaf of pure gold; it will disappear in a short time, uniting with the chlorine to form chloride of gold. It is the only substance that will dissolve gold (nitro-hydrochloric acid dissolves gold, but it does so because it probably contains free chlorine). Chlorine combines thus with many of the metals, forming chlorides of the respective metals, as has already been re- ferred to in case of antimony and arsenic. Copper in the form of wire or sheet burns in chlorine gas, forming a solution of copper chloride. If into this latter solution a piece of bright iron or steel is placed it very soon becomes covered with a red coating of copper. In chemical reac- 78 PHARMACEUTICAL AND MEDICAL CHEMISTRY. tions the right of the strongest prevails, and the chlo- rine, possessing stronger affinity for iron than for copper, seizes the iron, forming a chloride of iron, and liberates copper, which is deposited in the metallic condition. Polished steel is, therefore, a reagent for copper and may be employed to ascertain the presence of copper very simply and quickly. Copper is sometimes detected in this way if present in pickled cucumbers or preserved fruit, to which it is sometimes added to give a fresh-green color. 7. Showixg the Test of Iden"tity of Chlorixe iif CoMBiXATiOK" AS Chloride. — To a solution of any chlo- ride add solution of silver nitrate — a heavy white precipi- tate will be formed which is insoluble in nitric acid, but quickly soluble in ammonia-water. Chlorates when heated evolve oxygen, the residue being chlorides. Chlorine in Pharmacy. — Aqua chlori, U. S. P. has been already incidentally considered. Calx Chlorata. — This is a compound resulting from the action of chlorine upon calcium hydroxide (slaked lime), and containing at least 35 per cent, of available chlorine. It is erroneously called chloride of lime — properly it should be termed clilorinated lime. Calcium hydroxide, Ca(0H)2, placed in trays in suitable chambers, is exposed to the action of chlorine, which is absorbed by the lime, forming a compound having the formula CaCl2Ca(C10)2. Its formula is sometimes written CaOCl, (the former divided by two), which gave rise to the name Ghloiide of lime, the CaO being the formula for lime and the Cl^ de- noting chloride. In correct chemical nomenclature we cannot recognize the latter name. It is proper, though, to speak of the compound as cliloY'mated lime, the hydroxide PHARMACEUTICAL A^B MEDICAL CHEMISTRY. 79 being made from lime, CaO, by adding water or slaking it: CaO + H,0 = Ca(OH), Chlorinated lime is valuable chiefly for the chlorine it contains, and which is easily available, being very loosely combined. It is used largely as a disinfectant through its power of arresting decay and putrefaction. Sometimes, though rarely, it is used internally. Its chief use in phar- macy is to make the solution of chlorinated soda of the Pharmacopoeia, or Labarraque's Solution. The manufacture and introduction into the market of chlorinated lime, or bleaching -poivder, as it is frequently, termed, was brought about by manufacturers being pro- hibited from allowing the chlorine which was a by-prod- uct in many processes of manufacture, to escape into the air. .Air containing chlorine is not fit for breathing, nor is water containing chlorine fit for fishes to live in, as the manufacturers soon learned when they tried to dispose of their waste chlorine by conducting it into the rivers. At a loss what to do with it, they began experimenting, and soon a chemist suggested passing it into lime. His sug- gestion was adopted readily, but it was not thought that this apparently useless product would soon be in such demand that more than waste chlorine would be necessary to make enough to supply the need for it. Exposed to the air it emits chlorine spontaneously; if it is desired to have the chlorine evolved rapidly, a little hydrochloric acid added will hasten the disengagement of the gas. Bleaching-powder should be preserved in well-closed vessels and kept in dry places. Liquor Sodse Chloratae. — The solution of chlorinated soda is another convenient form for the use of chlorine. 80 PHARMACEUTICAL AND MEDICAL CHEMISTEY. It is made by adding solution of common washing-soda, sodium carbonate, to solution of bleaching-powder. The calcium is replaced by sodium : Calcium Sodium Calcium Sodium ypochlorite. Carbonate. carbonate hypochlorite Oa(ClO), + Na.CO, : = CaC03 + 2]S[a010 The calcium carbonate is insoluble and settles to the bottom, when the clear soda solution can be poured off. If potassium carbonate is employed in place of the sodium salt a corresponding potassium hypochlorite will be formed, the solution of which is known as Javelle's water. The values of both these solutions are equal. Hydrochloric and other acids containing chlorine will be referred to in the chapters on acids. Iodine. Occurrence in Nature. — Like other halogens, iodine oc- curs in nature chiefly combined with sodium and potas- sium; combinations with other bases are sometimes found. It chiefly occurs in the sea-water, but certain springs furnish it in large proportion. Source. — Many marine plants have the power of absorb- ing or abstracting the combinations of iodine from sea- water and storing them in their tissues, and this source — marine plants — furnishes all of the iodine in commerce. Preparation. — To obtain the iodine from the plants, the latter are burned, and the ashes, which are known as help, are lixiviated — that is, water is passed through them, as the menstruum is passed through the drug in the process PHARMACEUTICAL AI^D MEDICAL CHEMISTRY. 81 of percolation. The solution thus obtained is filtered and concentrated by evaporation, allowing it to cool at times, to permit the other less soluble salts to crystallize. The chloride and carbonate of sodium and the chloride of potassium — all salts found besides the iodides in the ashes of sea-plants — crystallize out in the order named, leaving the iodides, because most soluble, to remain until last in solution. The dark-brown liquid which is left, called the mother' liquor (a mother-liquor is that liquid which is left, in any process of crystallization, after one or more crops of crys- tals have been separated), and which contains the iodine almost wholly as iodide of sodium, with some iodide of magnesium, is treated in a manner exactly analogous to that employed in making chlorine, viz. : it is treated with sulphuric acid and dioxide of manganese and gently heated in a retort, usually a leaden one, when the iodine distils^ or better, sublimes over, and is condensed and collected in a receiver. Theoretically the operation is similar to that for obtaining chlorine in one case. 2]SraI -f 2H,S0, -f MnO, == 2B.fi + Na,SO, + MnSO, + I,. In this and many other chemical respects iodine closely resembles chlorine and the other halogens. Of late years considerable iodine has been obtained in Chili from the mother-liquors obtained from the crystalli- zation of nitrate of sodium, which is abundant there as an efflorescence on the soil. Purification. — The iodine as thus obtained is in very impure condition, the main impurities being iodide of 83 PHARMACEUTICAL A^D MEDICAL CHEMISTRY. cyanogen, or cyanide of iodine as it is frequently termed, chloride of iodine and water. To remove these, resuUima- tion is resorted to. The crude iodine is first very gently heated in proper vessels to allow the more volatile chloride and cyanide to escape; increased heat then sublimes the iodine; water is removed by bringing in close proximity with freshly-burned lime ; the lime abstracts the water : CaO + H,0 = Ca(OH),. Detection of Impurities. — When the iodine adheres to the interior of the bottle it does so because of the presence of water. Sometimes as much as 10 or 15 per cent of water is present, but its presence is injurious only in so much that it renders preparations made from it weaker than they should be. If iodine containing water is shaken with chloroform it does not give a clear and limpid solu- tion, but a milky onC, from which the water will separate if allowed to stand for some time. Chloride of iodine, if present, gives to water shaken with the iodine a brownish color, a deep brown one if much is present. To detect the cyanide the pharmacopoeia directs : If the iodine be removed from a dilute aqueous solution by agitation with disulphide of carbon, and, after the separation of the latter, some dilute solution of ferrous sul- phate, with a trace of ferric chloride, be added, and finally solution of soda, and the v\^hole supersaturated with hydro- chloric acid, no blue precipitate should make its appear- ance. Properties. — Iodine is in form of crystalline scales of a bluish-black color and metallic lustre. It is nearly five times as heavy as water, in which it is only very sparingly soluble; soluble in alcohol, ether, chloroform and disul- phide of carbon. At ordinary temperatures it volatilizes PHARMACEUTICAL AND MEDICAL CHEMISTRY. 83 slowly; when heated it melts and rises as purple vapors, which are the heaviest aeriform vapors known. Applied to the skin iodine imparts a deep brown stain, which may be removed with ammonia-water. Iodine precipitates most of the alkaloids, forming insol- uble compounds with them. In chemical behavior iodine resembles chlorine, but its chemical behavior is weaker. Its symbol is I; its atomic weight, 126.85. Compounds. — Iodine combines with many of the non- metallic elements and with most of the metals, forming iodides and iodates. With oxygen it forms principally the I3O5 and three acids — the iodous, iodic and periodic. Of the iodides, those of potassium and sodium are most important in pharmacy, with the ammonium and iron following. The hydrogen iodide, hydriodic acid, and the iodides of mercury, too, are largely used. The iodine in these is loosely combined, wherefore the salts should be kept in well-stoppered bottles, away from sunlight and in a cool place. Pharmaceutical Preparations. — The Tincture of Iodine is probably the most largely used preparation of iodine. It is made by dissolving 70 grammes of iodine in enough alcohol to make 100 cc, and should be made frequently and in small quantity, as the iodine reacts with the alcohol, especially when exposed to sunlight. It is used mainly externally, though at times it is given internally. Water decomposes the tincture, with a separation of the iodine. Next to the tincture in importance is the Compound Solution of Iodine, or Lugors solution, which differs from the tincture in being a solution of iodine in a solution of iodide of potassium. Iodine alone is not soluble in water, but in the presence of iodide of potas- 84 PHAKMACEUTICAL AND MEDICAL CHEMISTRY. sium it becomes readily soluble, and an aqueous solution is tbus possible. Five parts of iodine and 10 parts of iodide potassium will dissolve in 85 parts of water. This solution is intended mainly for internal adminis- tration, and its medicinal value depends not upon the iodide of potassium but upon the iodine, and the dose should be regulated according to it. There is no chemical reaction between the iodine and potassium iodide, the latter acting simply as a mechanical solvent. The preparation of the Ointment of Iodine depends upon the same fact. Four parts of iodine are rubbed with one part of potassium iodide and two parts of water, and, finally, with enough benzoinated lard to make 100 parts. The object of the water and potassium iodide is to bring the iodine into a state in which it may be thor- oughly and equally incorporated with the lard. Alcohol was formerly used to effect solution of the iodine, but the present method has been found to be a better one. A little glycerin obviates the formation of crystals in the ointment, which sometimes happens. If kept for a length of time this ointment undergoes change, hence it should be prepared when wanted for use. It is used whenever iodine is indicated and the ointment is the more con- venient form of administration. Iodized Starch is obtained by triturating starch and iodine with a little water and drying. It is used inter- nally, but is not of much importance. Tests For Iodine and Iodides. — Free iodine gives a characteristic deep blue color with starch-paste. The latter is made by toiling a small quantity of starch with water. Chlorine having more affinity for bases than iodine, the PHARMACEUTICAL AND MEDICAL CHEMISTRY. 85 latter can be liberated from iodides by treating their solu- tion with chlorine-water. Strong sulphuric acid dropped on any dry iodide also causes the iodine to be set free. Any iodide gives, with a solution of silver nitrate, a yellowish-white precipitate, which is insoluble in nitric acid and but slightly soluble in ammonia-water. (Chlo- rides give a white precipitate, readily soluble in ammonia.) Mercuric chloride, or any soluble mercuric salt, gives, with an iodide, a red precipitate of mercuric iodide. Any soluble lead salt produces a yellow precipitate with an iodide. Bromine. Occurrence in Nature. — Bromine, the third of the halo- gens, occurs in the sea and saline springs principally as bromide of calcium, sodium and magnesium. Preparation. — It is chiefly obtained from bittern, the mother-liquor, obtained by evaporating hrine from salt- wells. The mother-liquor containing the bromine, chiefly as magnesium bromide, is treated with chlorine, which, how- ever, having greater chemical affinity for the bases, com- bines with magnesium, in this case, setting the bromine free. (It must be remembered that chlorine has the great- est affinity of the halogens.) The bromine is condensed and collected in cooled receivers under water. This equa- tion expresses the reaction : MgBr^ + 01^ = MgCl^ -f Br^. Properties. — Bromine is the only liquid non-metallic element. At ordinary temperatures it is a dark-brownish red, mobile liquid, giving off brown fumes of an exceed- ingly offensive and suffocating odor; it is very volatile \ 86 PHARMACEUTICAL AlTD MEDICAL CHEMISTRY. and must be kept under water, in which it is not very soluble. It is freely soluble in ether, carbon disulphide and alcohol, and has a specific gravity of 2.99. Symbol, Br; atomic weight, 80. Great care should be exercised in handling bromine. Compounds. — Of the compounds containing bromine, the bromides of potassium, sodium, ammonium and hydrogen are the most largely used. They will all be considered under the respective bases. ■Tests for Bromine and Bromides. — Chlorine-water will liberate bromine from its combinations. Its odor is very characteristic. With starch it gives a yellowish color (iodine gives blue). Bromides, like iodides, give with silver nitrate a yellowish-white precipitate, insoluble in nitric acid and sparingly in ammonia-water. Strong sulphuric acid added to any dry bromide liberates vapors of bromine. Fluorine. This element is of little or no importance in medicine and pharmacy. It occurs chiefly as fluorspar (calcium fluoride). In its elementary state fluorine is scarcely known, because it so quickly and fiercely combines with all kinds of substances that chemists have had great difficulty in obtaining it in a free condition. Hydrofluoric acid attacks glass with such force that it is largely employed in the arts for etching on glass. PHARMACEUTICAL AKD MEDICAL CHEMISTRY. 87 Sulphur. Occurrence in Nature. — In Sicily and other parts of the world sulphur is found in the free or uncombined state, while as sulphides and sulphates it is very widely diffused, In its free condition it is found in the neighborhood of volcanoes, usually in opaque, crystalline masses, but some- times in beautiful transparent yellow crystals. It is found as sulphides in combination with iron, copper, lead and mercury; as sulphates with calcium, barium, magnesium. Preparation. — The crude sidphur is simply heated until it volatilizes, and the vapors cooled — that is, it is suhlimedy which in a measure purifies it. Iron pyrites or iron sul- phides yield a large quantity of sulphur when heated or sublimed. Properties. — Sulphur when pure is a pale-yellow solid, permanent in the air, insoluble in water, soluble in disul- phide of carbon, from which it may be crystallized. When heated, sulphur melts and distils or sublimes, unaltered, if air is absent ; in presence of air it takes up oxygen and becomes sulphur dioxide gas, SOj, just as it does when it burns. There are two forms of crystals of sulphur — an octahedral (eight-sided), in which the native sulphur sometimes occurs, and the monoclinic, obtained when a mass of sulphur is melted and, after partial cooling, the crust on the surface is broken and the fluid portion poured out. The crystals adhere to the inner portion and protrude into the space left by the portion which had not yet cooled and was poured out. The former is sometimes spoken of as the octahedral variety, and the latter as the prismatic variety. The former has a specific gravity of 2.04, while the prismatic weighs only 1. 96 times as much as 88 PHARMACEUTICAL AN"D MEDICAL CHEMISTRY. water. Sulphur melts at 218° P., and boils or volatilizes at 752° F. It is interesting to notice that when sulphur is heated to the melting-point it forms a thin amber-colored liquid, which, when further heated, begins to thicken and becomes of a deeper color. At 430° or 450° F. it becomes very thick and tenacious, so much so that the vessel con- taining it may be inverted without losing its contents. If this now be poured into water and quickly cooled it be- comes a very soft and flexible solid, which gradually hardens and becomes brittle. This condition may be looked upon as an amorphous one. From the last-mentioned temperature up to its boiling- point, 752° F., sulphur again begins to become thin and limpid. Sulphur, in its chemical relation, bears some resemblance to oxygen; many of the oxides have corresponding sul- phides; for instance: HgO, Mercuric oxide. HgS, Mercuric sulphide. CaO, Calcic oxide OaS, Calcic sulphide. FeO, Ferrous oxide. FeS, Ferrous sulphide. Fe^Og, Ferric oxide. Fe^Sg, Ferric sulphide. PbO, Lead oxide. PbS, Lead sulphide. Official Sulphurs. — The pharmacopoeia recognizes the sublimed, washed and 2)'^ecipitated sulphur, the ointment and the sulphur iodide. Sublimed Sulphur.— Vapors of sulphur when con- ducted into a cooled chamber become condensed in the form of a crystalline powder, which deposits upon the bottom and walls of the chamber, constituting the variety of sulphur known as the sublimed. Flowers of Sulphur, as it is frequently called^ usually PHARMACEUTICAL AlTD MEDICAL CHEMISTRY. 89 has an acid reaction, due to the absorption of oxygen and water, forming sulphurous and sometimes even sulphuric acid. This is not a very pure product; it may contain other impurities besides the acid, sometimes even traces of arsenic, especially if made from the iron pyrites. To insure purity the sublimed sulphur is washed with am- monia-water, yielding a product official under the name Washed Sulphur. The ammonia-water serves two pur- poses — it neutralizes the acid, forming sulphite and sul- phate of ammonium : Sulphuric Ammonia Water. Ammonium acid. water. sulphate. H,SO, + 2NH,0H : = 2H,0 + (NHJ,SO., and dissolves out any arsenic that may be present. Sub- sequent washing with much pure water insures the total removal of the salts thus formed. The U. S. P. gives a test to ascertain the absence of arsenic. If the sulphur is digested with ammonia-water and filtered, the filtrate, if arsenic is present, turns cloudy when supersaturated with hydrochloric acid. This depends on the fact that arsenic is soluble in the alkali, but insoluble in the acid. The cloudiness would be due, therefore, to .the precipita- tion in the acid solution of the arsenous sulphide. Or if the above filtrate be treated with sulphuretted hydrogen, made by acting on sulphide of iron in a test-tube with sulphuric acid, FeS -f H^SO, = FeSO, + H,S, no precipi- tate should be produced, showing the absence of arsenous oxide. This form of sulphur is preferred by some for internal administration. The Precipitated Sulphur is much lighter and more easily suspended in liquids, and is therefore preferable to 90 PHARMACEUTICAL AI^D MEDICAL CHEMISTRY. the other forms of sulphur. It is made by boiling together the sublimed sulphur and lime, filtering the solution and adding hydrochloric acid: Lime. Sulphur. Bisulphide calcium. Thiosulphate of calcium. 3CaO + 3S, : = 20aS, - h CaS,0, The solution containing the above calcium salts, when treated with hydrochloric acid, separates the sulphur in a finely-divided state : Calcium chloride. 2CaS, + CaS,03 + 6HC1 = 3S, + 3CaCl, + 3H,0 The precipitate is thoroughly washed with much pure water. The test applicable to the washed sulphur may be applied to this form of sulphur. If sulphuric acid be employed in place of hydrochloric, the precipitated sulphur is contaminated with calcium sul- phate, which is formed in the operation, and which, because it is insoluble, cannot, like the chloride of calcium, be washed out: Precipitate. 2CaS, + OaS,03 + 3H,S0, = 3S, -f 3CaS0, -f 3H,0. This kind of precipitated sulphur is known as milk or lac sulphur, and should not be mistaken for the official form. Iodide of Sulphur. — By rubbing together very thor- oughly washed sulphur and iodine, and heating in a flask, carefully at first, not to dissipate the iodine ; increasing the heat, when combination has taken place, to liquefaction; allowing to cool, breaking the flask and reducing the fused mass to small pieces, the iodide of sulphur is obtained. It is in the form of a grayish-black solid, and when exposed PHARMACEUTICAL AND MEDICAL CHEMISTRY. 91 to the air gradually loses its iodine, the latter being very loosely combiaed with the sulphnr. Its use is chiefly ex- ternally, as ointment in skin diseases. Sulphur Ointmekt. — Made by rubbing sublimed sul- phur with benzoinated lard. This is a convenient form for the administration of sulphur when the small propor- tion of acid present in the sulphur is of no consequence. Alkaline Sulphur Ointment. — This was introduced into the 1880 pharmacopoeia, and is made with ivaslied sulphur potassium carbonate (the latter giving it its alkalinity, and hence its name) and benzoinated lard. With hydrogen sulphur forms a gas known as sulphur- etted hydrogen, or hydrosulphuric acid gas, which is of considerable importance in that it is one of the important reagents in pharmaceutical testing. Its composition is H^S, one of those combinations in which sulphur has only two bonds, and which are known as sidpliides, exemplified in the sulphide of iron, FeS; sulphide of lead, PbS, etc. H^S is an acid corresponding to those acids formed by the union of any of the halogens with hydrogen- — that is, it is one of those acids containing no oxygen, and which be- long to the hydrochloric-acid type, HOI. It may be ap- propriately mentioned here that in The Writing of Salts Or acids — that is, expressing their composition by means of symbols — among others, two types, the HCl type and the H^O or water type, are employed. For example, we may make, theoretically, a number of acids from hydrochloric acid by replacing its chlorine with some other one element: HCl, with the chlorine replaced by bromine, gives HBr, hydrobromic acid ; in like manner, 92 PHARMACEUTICAL A:N"D MEDICAL CHEMISTRY. HI^ hydriodic acid, HFl, hydrofluoric acid, etc., may be obtained. It will be noticed that the elements in the above acids all have one bond; an element replacing another must have an equal number of bonds in these cases. If the chlorine in the hydrochloric acid should be replaced by sulphur it would be necessary to employ at least two mole- cules of the acid, because sulphur, having two bonds, would replace two atoms of any element having only one bond; 2HC1 or H2CI2 with the Clj replaced by one atom of sul- phur would give H^S. All acids, therefore, containing only two kinds of atoms may be said to be derived, theo- retically, from one or more molecules of hydrochloric acid in which the chlorine is replaced by an equiv- alent of some other element. The hydrogen must not be replaced, because it forms the base of all acids, and when it is removed the combination is no longer an acid, as we shall see presently. The other type, the water type, differs from the former in having one of the hydrogen atoms in water replaced usually by two or more other elements, one of which must be oxygen. Water is H^O, or H — — H; the right-hand hydrogen is the one that may be replaced. Nitric acid, HNO3, may be looked upon as H — — H in which the one H is replaced by NO, thus, H — — NO^. The group of elements replacing this one hydrogen must have, together, one free bond; in this case the nitrogen has five bonds, and two atoms of oxygen together four bonds, which unite with four of the nitrogen, leaving one bond still free. NO^, therefore, is the equiva- lent in combining power of a single atom having one bond, and can replace the one atom of hydrogen in water, just as bromine can replace the chlorine in hydrochloric acid. PHARMACEUTICAL AI^D MEDICAL CHEMISTRY. 93 Sulphuric acid, H^SO^, because it has two hydrogen atoms, is derived from two molecules of water: H— 0— H H— 0— H, in which two atoms of hydrogen, one from each molecule of water, are replaced by SO 2, sulphur dioxide : iZo/SO,, or H,SO.. Phosphoric acid is derived from three molecules of water, H— 0— H H— 0— H, H— O—H, in which the three atoms of hydrogen are replaced by PO : H— 0\ H— O^PO. H— 0/ In the case of sulphuric acid the S has six bonds, four uniting with the four of the two atoms of oxygen and the other two replacing the two hydrogens. Together, there- fore, SO, has two free bonds. For a similar reason PO has three bonds, two of the five which phosphorus has uniting with the two bonds of the one oxygen, and the other three replacing the three hydrogen atoms in the three molecules of water. All acids may be thus classed in one of these two types, hydrochloric acid being the type for all acids containing no oxygen, while those containing oxygen are relegated to the water type. The student is earnestly advised to get the formulas of a number of acids — inor- ganic acids — from any text-book, and classify them into 94 PHARMACEUTICAL AND MEDICAL CHEMISTRY. the two types mentioned. There are other types to which reference may be had later on. Now a step further. Salts, in a general sense, may be said to be acids in which the hydrogen has been replaced by a metal. Sulphate of magnesium, MgSO^, is a salt de- rived from sulphuric acid, H2S0^, by replacing the hydrogen with magnesium. If the H in HNO3 ^^ replaced by sodium, Na, NaNOg, sodium nitrate, results; in a like manner, NaCl, sodium chloride, common table-salt, is HCl with the H removed and supplanted by Na, sodium or natrium. In the case of monad metals, there must be as many- atoms as there are hydrogen atoms in the acid : HOI with Na yields NaCl, Sodium chloride. HNOg with Na yields NaNOj, Sodium nitrate. H^SO^ with Na yields Na.SO^, Sodium sulphate. H3pO^ with Na yields NagPO^, Sodium phosphate. When the metal has more than one bond an equivalent of the acid must be employed: 2IIC1 with Ca yields CaCl^, Calcium chloride. 2IINO3 with Ca yields Ca(N03), Calcium nitrate. H2SO4 with Ca yields CaSO^, Calcium sulphate. 2H3PO, with 3Ca yields CagCPOJ^. Calcium phosphate. To make the salt calcium chloride we must remove the hydrogen from two molecules of hydrochloric acid, be- cause Ca is a dyad ; for the same reason we must employ two molecules of HNO3 to make calcium nitrate. To make the calcium sulphate only one H^SO^ is necessary, because that contains the necessary H^. In trying, to thus write the formula for phosphate of calcium the student may be puzzled a little at first, but he will have no trouble PHARMACEUTICAL AN^D MEDICAL CHEMISTRY. 95 if he will only remember that the base in the salt must have as many bonds as there are bonds in the base of the acid, and that he may employ more than one molecule of the acid if necessary. Ca has two bonds, but there are three hydrogens to be replaced. The easiest thing to do is to find the lowest multiple of the two numbers, in this case 2 and 3, which is 6. Six, then, is the number of hydro- gens that there must be in the acid, hence we take the acid twice, 2H3PO^. The base of the salt, then, also must con- tain six bonds; and 3Ca have six bonds, hence the formula of the salt will be Ca3(P0j2. In thus producing salts from acids there is merely an interchange of bases, of course governed by the number of bonds of the respective bases. It may be well to state here that a salt is by some looked upon as consisting of two parts, a hase and a radical, or, as some chemists prefer, of a basylous and an acidulous rad- ical. In potassium nitrate, KNO3, the K is the base or basylous radical, while the NO3 is the radical, or acidulous radical. Acids are salts, but the term acid is specific, and means a salt containing hydrogen as its base. The salts thus far spoken of are all neutral salts — that is, they are such that are derived from acids by replacing all the hydrogen of the latter by a metal. Now, it is possible to -remove only part of the hydrogen with a metal, as is the case with bicarbonate of sodium, NaHOOj, which is carbonic acid, H^COg, with half its H replaced by sodium. Cream of tartar, KHO^H^Og, is obtained by removing one H from tartaric acid, H^C^H^Og, and putting one of potas- sium in its place. Such salts are distinguished from the neutral salts by special terms; they are acid salts or Usalts. We distinguish another kind of salt, the double salt, exem- plified in Rochelle salts, the tartrate of potassium and 96 PHARMACEUTICAL AND MEDICAL CHEMISTRY. sodium. Tartaric acid, H^C^H^Og, containing two hydro- gen atoms in the base, has one replaced by potassium and the other by sodium, KNaO^H^Og. Here the base consists of two metals. The student is recommended to read again, very carefully, the chapter on Chemical Notation and Nomenclature. But to return to sulphur. As already said, in H^S we have a valuable reagent. When it comes in contact with the solutions of a great many of the metals it gives its sulphur to them, forming characteristic precipitates. Thus lead with H^S gives a very black precipitate, while zinc yields a white one and arsenic a yellow one. These pre- cipitates are sulphides — that is, the direct union of a metal with sulphur alone. H^S may be made by acting on sul- phide of iron with sulphuric acid: FeS + H^SO^ =FeSO^ + HjS. It has a very disagreeable odor, is soluble in water and in water of ammonia. The latter solution is also an official test-solution, that called ammonium sul- phide. Sulphuretted hydrogen is the chief constituent of sulphur-waters. The sediment found in these waters at times is sulphur, due to the decomposition of the gas, setting the sulphur free. The other acids of sulphur will be considered in the chapters on acids. Phosphorus. Occurrence in Nature. — Phosphorus never occurs in a free state in Nature, but is most usually found in the form of phosphates of some of the metals, principally of calcium, sodium, potassium, iron and aluminum. The soil contains PHARMACEUTICAL AI^D MEDICAL CHEMISTRY. 97 a considerable quantity, and is fertile in proportion to the amount of it present. Soil, it should be understood, is the result of the disintegration and tumbling down of the ancient unstratified rock, and of some of modern origin, and these ancient rocks having contained phosphorus as phosphates, the latter is now present in soil as a conse- quence. And that this is so is another illustration of the sublime economy of nature, for phosphorus is an essential constituent of plant food. Most plants could not exist were it not for the presence of phosphorus in the soil — this is shown on fields in which there have been many suc- cessive crops without the aid of artificial fertilizers — each successive crop becomes less abundant, because each previ- ous one has diminished the amount of phosphorus present. The phosphorus which thus passes into the organism of plants finds its way into the bodies of animals to which plants serve as food. The bones of animals are made up almost wholly of phosphate of calcium, thus indirectly de- rived from the soil through the intervention of the plant world. The salt plays an important part in the animal frame, the skeleton of man and animals being largely com- posed of it. Source. — Phosphorus is chiefly obtained from bones, which contain 60 per cent of phosphate of calcium, or tricalcic phosphate, Csi^(POJ^. Formerly it was obtained from urine. Brandt, of Hamburg, a chemist, discovered it in this excretion in 1669, and for a long time that was its only source. On account of the small yield it was very scarce and expensive at first. Preparation. — Nowadays phosphorus is prepared from bones, which are first calcined and then reduced to a fine powder. Calcination removes the fat and all other organic 98 PHARMACEUTICAL AN"D MEDICAL CHEMISTRY. matter which heat will destroy, leaving as residue a salt which is mainly calcium phosphate. The powdered cal- cined bones are then mixed with sulphuric acid diluted with water, and the mixture allowed to stand, to per- mit the insoluble sulphate of calcium which is formed to deposit. The tricalcic phosphate (having three atoms of calcium) Csi^(PO^)^, becomes converted into a monocalcic (mono = one) phosphate, which is soluble and remains in solution: Ca3(P0J, + 2H,S0, = CaH,(POJ, + 2CaS0,, After standing for several hours the supernatant liquid is poured off from the deposited calcium sulphate, filtered and evaporated to a syrupy consistency, mixed with pow- dered charcoal, and the whole thoroughly dried in a vessel exposed to a high temperature. When quite dry the resi- due is introduced into a stoneware retort and carefully heated again; vapors of phosphorus are distilled and care- fully collected under water 3CaH,(P0J, + 50 = Ca3(P0j, -f 4P + 6H,0 + SCO,. The Oa3(POj2 remains in the retort together with some charcoal; the mixture is incinerated, thereby removing the charcoal and fitting the bone phosphate for treatment with sulphuric acid, to convert it again into the soluble phos- phate. This method is the one usually employed, and by it 100 pounds of fresh bones yield from 6 to 7 pounds of phosphorus. Another method resembling the above is coming into very frequent use. Instead of mixing the soluble phosphate with charcoal alone, sand is added and the process conducted as above. (Sand is mainly oxide of silica) : 20aH4(POj2 + 2SiO, + 100 = 20aSi03 + lOOO + 4P + 4H,0. The sol- uble phosphate, CaH^(P0j3 is probably first converted PHARMACEUTICAL AITD MEDICAL CHEMISTRY. 99 during the process of heating into the metaphosphate : CslH.^(PO^)^ -\- heat = Oa(P03)2, metaphosphate of cal- cium, and 2H2O, water. Extreme care must, be exercised in manipulation in these processes; they should not be attempted by the student. Properties. — Phosphorus is a soft, flexible solid, colorless, translucent when recently prepared, and of the appearance of imperfectly bleached wax. When exposed to light and time it gradually becomes less translucent, finally opaque, white, yellow and finally red. The latter conditions are allotropic ones, which will be alluded to again. Phos- phorus has a specific gravity of 1.77 to 1.83, melts at 44° 0., and boils at 280° 0. When it is slowly cooled it sometimes crystallizes in well-formed dodecahedrons. It is insoluble in water, soluble in oils, ether, chloroform and very soluble in disulphide of carbon. In air it very quickly oxidizes and takes fire spontaneously. Its name signifies " bearer of light," and was given it on account of its prop- erty of being luminous in the dark. " If touched it took fire and burned furiously, exhaling a dense white cloud, which gathered like fleeces of snow, but, unlike snow, hiss- ing like a red-hot iron when touched with water, or, if brought into contact with the skin, blistering it like living fire." In this way did Brandt refer to its properties after he discovered it. They spoke of it at the time as " the son of Satan." It is exceedingly inflammable, taking fire from the heat of the hand or from a blow or hard rub. Sun- shine ignites it immediately. This is due to its great affin- ity for oxygen, with which it combines very energetically, and, in consequence of which property, it has to be kept under water, upon which it has no effect. A stick of 100 PHAKMACEUTICAL Ai^^D MEDICAL CHEMISTEY. phosphorus, when exposed to the air, always emits a whit- ish smoke or cloud, due to a slow combustion which the phosphorus undergoes with the oxygen of the air, and upon which one of the methods for the analysis of the air de- pends. The white fumes which it emits when burning are PjO^, phosphoric oxide, which will be referred to again. The burns caused by phosphorus are exceedingly painful and produce sores which are difficult to heal; the greatest care must be taken in handling it. Allotropic Coi^ditions. — Among the remarkable prop- erties of this singular substance is the diversity of its allo- tropic conditions, of which it assumes five. The ordinary translucent vitreous phosphorus when exposed to light under water changes to the first allotropic variety, which is white, opaque and less fusible. The second variety is the crystalline, obtained by evaporating some of its solutions; the thirdf a black, opaque variety, produced by the sudden cooling of melted phosphorus : a fourth allotropic condi- tion is obtained by suddenly cooling phosphorus when it is near its boiling-point, when is yielded a soft, elastic sub- stance, analogous to viscous sulphur, described when treating of sulphur ; the fifth, called red phosphoi^us, is obtained by exposing phosphorus to the sun under water, or by expos- ing it to the sun between plates of glass. The latter amor- phous variety may also be obtained by heating common phosphorus in carbonic acid gas, or in any atmosphere that will not act on it chemically. It may be looked Upon as the passive condition of phosphorus, as it is devoid of many of the energetic properties of the ordinary or active variety. It is red in color, heavier than the former, is not luminous, nor does it melt at the boiling-point of water. It exhales no vapors or odor, oxidizes but very little in the PHARMACEUTICAL AN^D MEDICAL CHEMISTRY. 101 a.r, does not change oxygen into ozone, is chemically indif- ferent toward other elements, may be handled with impun- ity or carried exposed in the pocket, and is not poison- ous when administered in doses a hundred times larger than would be fatal in the common form (Gr. Wilson). It is peculiar also in that it changes into the active form and bursts into flame at 500° F. Poisonous Properties of Phosphorus. — This element is relegated to the list of active poisons, and the student cannot be often enough impressed with its toxic proper- ties. Taken internally in larger than therapeutic doses it acts as a violent poison, being all the more toxic because there is no specific antidote for it. Two kinds of phos- phorus poisoning are usually distinguished — the acute form and the chronic. The former results upon ingestion of an excessive amount, while the chronic form affects especially workmen employed in the manufacture of matches, an industry which is very extensive. Oil of tur- pentine has been recommended as an antidote, but some authors oppose its use, on the ground that it dissolves the phosphorus, rendering it even more active. The stomach- pump and emetics and, later, cathartics should be em- ployed to eliminate as speedily as possible the phosphorus in a mechanical way. It must be borne in mind that this poison is soluble in oils or fats, and hence these should not be given, not even milk, since that contains considerable fat. Experiments. — The student is fully aware by this time of the danger connected with the handling of phosphorus, but yet he should have enough confidence to undertake a few experiments which will make him learn to exercise care in the manipulation of a dangerous substance. 102 PHARMACEUTICAL AN^D MEDICAL CHEMISTRY. Put into a flask, having a well-fitting cork, a small piece of phosphorus by means of small pincettes, add two or three drams of ether and allow to stand for a few days, shaking occasionally. The ether will dissolve most of the phosphorus. Several drops of this solution poured upon the hands and these quickly rubbed together will cause the ether to evaporate and the phosphorus to remain upon the hands in a state of minute division. The phosphorus soon begins to become luminous, causing the hands to shine in the dark, the luminosity becoming more intense upon rubbing the hands, as a fresh surface of phosphorus is thus continually presented to the oxygen of the air. Heat is produced, but it is too feeble to occasion ignition; it is slow combustion. The phosphorus unites chemically with the oxygen of the air, producing one of the oxides of phosphorus, which in turn combines with the water in the air to produce phosphoric acid. If a lump of sugar be moistened with the ethereal solution of phosphorus and thrown into hot water, the heat of the latter causes the ether to volatilize, and the phosphorus rises to the top and there inflames spontaneously. In this case the combustion is brisk and complete, and the phosphorus takes up a larger amount of oxygen than above, forming the phos- phoric oxide, P2O5, and this with the moisture of the air, or with water, produces phosphoric acid. In the preceding experiment the oxide produced was the phosphorous Oxide, P2O3, which is always produced when phosphorus com- bines slowly and incompletely with oxygen, while, when the oxidation is complete — that is, when it is accampanied by flame — the higher phosphoric oxide, ^fi^, is always formed. Pour some of the ethereal solution of phosphorus upon PHAEMACEUTICAL AKD MEDICAL CHEMISTRY. 103 fine blotting-paper, and as soon as the ether will have evap- orated the paper will ignite spontaneously. If a little finely-powdered charcoal or soot is sprinkled over a small piece of phosphorus the latter melts after a while and spontaneously inflames. The charcoal causes this combustion; because of its porosity it absorbs oxygen from the air, imparts it to the phosphorus, and being also a non-conductor of heat prevents the cooling of it. A piece of phosphorus in a wine-glass will melt if hot water is poured upon it, but will not ignite because of the absence of air. If air be blown very carefully through a long tube upon the phosphorus a combustion will take place which is especially visible in the dark. An oxide of phosphorus is formed, but a much lower one than in any of the experiments, the phosphorus being in excess of the oxygen, in this instance, P^O. The three oxides men- tioned thus far, the P^O, P^Og and P^O^, will receive more attention later on, under Phosphoric Acid. The P^O may also be obtained by gently heating a small piece of phosphorus placed in the middle of a glass tube about a foot or 15 inches long. When ignition commences the heat should be withdrawn. The combustion is feeble and imperfect while the tube is held horizontally, because the heavy smoke, consisting of phosphoric and phosphorous oxides, passes off slowly, allowing the admission of only a small quantity of air. As soon as the tube is inclined the combustion becomes more vivid, and when the tube is held perpendicularly it becomes perfect, because of the draught of air through the tube. In this wise phosphorus may be oxidized to any of the three degrees. Uses of Phosphorus. — In the manufacture of matches we have one of the chief uses for phosphorus. Vast quantities 104 PHARMACEUTICAL AND MEDICAL CHEMISTRY. are consumed in this way. In making the matches the wood is cut by machinery, the ends first tipped with sul- phur, which is in a molten condition for the purpose, and then with an emulsion of phosphorus in ordinary glue, to which is added a little nitrate of potassium, oxide of man- ganese or chlorate of potassium. The latter bodies are all rich in oxygen. In igniting a match, the friction-heat produced by striking it against a surface is sufficiently high to cause the phosphorus to kindle and unite with the oxygen furnished by the nitrate or chlorate of potassium. The heat and flame produced by this chemical union be- tween the phosphorus and oxygen are sufficient to cause the sulphur to burn, which in turn ignites the wood. Not only is the manufacture of matches dangerous from the explosive nature of the materials used, but also because of the corrosive phosphoric vapors, which produce at times among the laborers a distressing disease known as caries of the lower-jaw. Improvements in the methods employed have lessened the danger of this dread disease. In treating of the occurrence in nature of phosphorus, we learned how essential it was to plant and animal life, how it came to be in the soil, and how it found its way through the vegetable world into the animal, where its function is most important in that it builds up the bony structure. It is also an important constituent of the brain and nervous system. After continued brain exercise there is always an increase in the proportion of phosphoric products in the liquid excretions. Phosphorus in Pharmacy and Medicine. — Phosphorus is official in four forms : as phosphorus in its unaltered state, as a solution in the form of Phosphorated Oil, in a minutely- divided form in the Pills of Phosphorus, and in a state of PHAEMACEUTICAL AKD MEDICAL CHEMISTRY. 105 combination with oxygen and hydrogen in Phosphoric Acid. There are other compounds besides these in which phosphorus occurs, but they are not made directly from phosphorus. The Pharmacopoeia directs phosphorus to be kept under water, in a secure and moderately cool place, protected from light. When phosphorus is intended for medicinal use it should be absolutely pure. The commercial article sometimes contains a little arsenic or sulphur, or both, which render it totally unfit for the purposes of medicine, and the pres- ence of which should be strenuously guarded against. To detect arsenic, a portion of phosphorus should be dissolved in nitric acid, water added, and the solution evaporated until all superfluous nitric acid is dispelled. Before the solution (which should be somewhat diluted) has thoroughly cooled a stream of hydrosulphuric acid gas, H^S, should be passed through it for half or three quarters of an hour. If arsenic is present a lemon-yellow deposit will be formed within twenty-four hours, abundant in proportion to the quantity of arsenic. If no deposit forms within that time, it may be assumed that there was no arsenic present. The Pharmacopoeia allows a slight quantity of sulphur to be present in phosphorus. If to the above solution a few drops of test-solution of chloride of barium be added, not more than a slight opalescence should make its appearance. The opalescence is due to the presence of sulphuric acid, which is formed by the action of the nitric acid upon traces of sulphur which are present. The dose of phosphorus is from yf^- to -^ grain. In large doses it acts as a poison. The medicinal value of phosphorus as a nervous stimulant seems only to be 106 PHARMACEUTICAL AND MEDICAL CHEMISTRY. obtained by administering it in a free state. The oxide of phosphorus, or phosphoric acid, has a different action, and hence the necessity of preventing the oxidation of the phosphorus. The pills and the phosphorated oil are in- tended for the administration of phosphorus in a free state. Phosphorated Oil is prepared by heating expressed oil of almond to about 250° C, allowing to cool, filtering, adding the phosphorus, heating again in a water-bath until the phosphorus dissolves, allowing to cool and adding ether. Phosphorated oil, when fresh, should be clear and colorless, or only slightly colored, phosphorescent in the dark, and have the taste and odor of phosphorus. The oil is first heated to expel air or water, which, if present, would oxidize the phosphorus. The ether, besides serv- ing to preserve the oil, also renders its taste less dis- agreeable. A good way of administering phosphorated oil is in milk or in the official emulsion of almonds; the dose is from 1 to 5 minims, the oil containing 1 per cent phos- phorus. Phosphorus Pills contain y^ grain each, and are made by dissolving the phosphorus in chloroform, adding this chloroformic solution to a mixture of marshmallow and acacia in a mortar, and quickly making a mass with glycerin and water. To prevent the oxidizing action of the air they are directed to be coated with balsam tolu which has been dissolved in stronger ether. The pills are shaken with a sufficient quantity of the tolu-ether solution and put away on plates to dry. The balsam forms a coating which is impervious to air or moisture. The pills should be kept in small, well-stoppered bottles. In making the solution PHARMACEUTICAL AND MEDICAL CHEMISTRY. 107 care should be taTcen not to use heat, as ether is very inflammable and volatile. Phosphoric Acid also is made directly from phosphorus, but that will be referred to in the chapter on acids. Boron. Boron is of some importance in pharmacy, being the chief chemical constituent of the important and much used borax and boric acid, and of all borates. Occurrence in Nature. — Boron is never found in the free state in nature, but most abundantly in boric acid and in sodium borate. The boric acid occurs in solution in the hot lagoons of Tuscany, while borax forms a crystalline deposit in many of the lakes of California and in those of Thibet and Persia. The borax obtained from the latter is imported in a crude state under the name of tincal, which is crystallized and purified here, though the main supply of our market is obtained at present from the lakes of California. A native borate of calcium is found in Southern Peru; this and the native boric acid from Tus- cany furnish a large proportion of the borax in the market. Besides these sources, horax springs furnish considerable borax. It is a peculiar fact that borax springs always con- tain ammonia. Preparation. — Boron is obtained by heating one of its compounds, boric acid, preferably, with magnesium in a suitable tube, and by continued washing in dilute hydro- chloric acid, washing out the borate and boride of mag- nesium which are formed. Boric Acid. — There are many compounds containing boron, but we confine ourselves to the two of importance in pharmacy, namely boric acid and borax. The lagoons 108 PHARMACEUTICAL AKD MEDICAL CHEMISTRY. of Tuscany formerly furnislied the greater part of the boric acid in commerce, but at present the most of it is obtained from the borax found in the lakes of California by decomposing it with hydrochloric acid. Borax is a biborate of sodium, NajB^O^lOH^O, which when treated with either hydrochloric or sulphuric acid, while in hot solution, has its sodium displaced by the acid, the hydrogen of the acid combining with the boric radical, forming boric acid, thus : {m.Bfl^ + lOH.O) + n,SO, = Na.SO, + 4H3BO3 + 5H,0, or (Na,B,0, + lOH.O) + 2HC1 = 2NaCl + 4H3BO3 + 5H,0. In the first instance sulphate of sodium is formed as a by-product; in the second, a chloride. Both these salts are very soluble and remain in solution, while the much less soluble boric acid separates upon cooling, and is purified by redissolving in pure water and again crystal- lizing. As thus obtained, boric acid is in transparent six-sided plates or scales, soluble in 25 parts of water; much more soluble in hot water. It is a weak acid compared with the other mineral acids, and turns blue litmus paper not red, like other acids, but only a wine-red color; while turmeric paper (porous paper soaked in solution of tur- meric) becomes brown in its contact with it. Alkalies have nearly the same effect on turmeric paper, but the brown color disappears on the addition of stronger acids. Turmeric paper turned brown with boric acid does not lose its color with acids, but turns bluish-black with ammonia- water. Boric acid, added to alcohol, imparts to the flame of the latter a green color. This is a characteristic property of PHARMACEUTICAL A^T) MEDICAL CHEMISTRY. 109 boric acid. The crystallized acid contains water of crys- tallization — H3BO3 + HjO — and when heated melts in this water, which volatilizes, leaving a glassy bead of an- hydrous boric acid, which is much utilized in blowpipe analysis. A piece of platinum wire, with a loop on the end, if wetted and dipped into boric acid, affords a con- venient means of exposing boric acid to the blowpipe flame. If a stream of air is directed through the blowpipe into the flame of a spirit lamp, or Bunsen-burner, and the wire with the acid brought near to the flame, the acid will first melt and swell in its water of crystallization, and finally will be converted into a transparent glassy bead. This bead consists of the oxide of boron, probably B^Og, which, in its molten condition, has the property of dissolv- ing many metallic oxides with very marked and character- istic colors. If this glassy bead be moistened and dipped into chalk or litharge, or into almost any oxide, and again heated to melting, these substances will unite most inti- mately with the boric oxide, and be dissolved by it, and assume a glassy, or, better, vitrified appearance. Most of the combinations of boric acid with oxides or bases become vitreous on heating — that is, they melt together, forming a white or colored glass. Chromium salts thus give a green color, manganese an amethyst, and cobalt a blue, etc. The official boric acid is only one of the many acids of boron, which will receive mention under Borax. The blowpipe is a very useful instrument for melting, oxidizing, reducing or volatilizing substances in small quantities. It is made in various shapes, but consists essentially of a metal tube bent a short distance from one end and drawn to a point. The proper use of the instru- 110 PHARMACEUTICAL AN"D MEDICAL CHEMISTRY. ment requires a little practice, which can be soon acquired. The blast should be steady and continuous, and should be produced principally by the* muscles of the cheek, the respiration not to interfere much. A double combustion takes place in the blowpipe flame, a smaller interior cone of a blue color and a larger exterior cone of a yellowish appearance. The latter is called the oxidizing flame, the former, the reduci7ig. If a substance is to be reduced — that is, deprived of its oxygen — it is held at the point of the inner flame, where it meets with soot or carbon, which combines with the oxygen of the substance and escapes as carbonic acid, leaving the substance reduced, or devoid of oxygen. If, on the other hand, a body is to be oxidized — that is, united with oxygen, then it is held at the point of the outer flame, where the oxygen of the air can have free access to it. It may be good practice for the student to convert a piece of lead, placed upon charcoal, into an oxide, by exposing it to the outer flame, and then reducing it, by exposing the oxide thus formed, to its original metallic state. Tests for Purity of Boric Acid. — The Pharmacopoeia re- quires boric acid, or, as it was formerly called, boracic acid, to be free from sodium and from sulphuric and hydrochloric acids, which may be present as a result of incomplete wash- ing after the acid is separated from its solution with either the chloride or sulphate of sodium. Lead, copper and calcium should also be absent. Barium chloride solution will give a white precipitate with sulphates, insoluble in any acid. Solution of silver nitrate yields a curdy white precipitate with chlorides, soluble in ammonia-water and precipitated upon addition of nitric acid. Calcium may be detected by the addition of a solution of ammonium PHARMACEUTICAL AND MEDICAL CHEMISTRY. Ill oxalate, which produces a white precipitate with soluble calcium salts. Lead, copper and iron give a black color and precipitate, with ammonium sulphide. The above tests are all characteristic, and not only ap- plicable in these cases, but in many others where the same substances are sought. It is well, therefore, that the student commit them to memory. Uses in Pharmacy and Medicine. — Boric acid is re- quired to be in a very fine impalpable powder for most medical uses. It is a good antiseptic, and is extensively employed in antiseptic surgery. Berated cotton, lint or gauzes and bandages are much used as antiseptic dress- ings to wounds. It is an excellent means of preventing fermentation, and is for that reason added to many liquids, to which it communicates but little taste. In form of ointment or dusting-powder it is much favored for external application. Borax. Borax is a sodium salt, usually termed in chemical lan- guage the borate or biborate of sodium. Its composition is expressed by the formula Na^B^O^lOH^O, which shows it to be composed largely of water of crystallization. It con- tains four atoms of boron, and may be looked upon as a salt of one of the many boric acids before referred to. As an illustration of the many acids of boron the follow- ing may serve : Beginning with one molecule of orthoboric acid, II3BO3, we may obtain another by abstracting one molecule of water. Beginning with successively two, three and four molecules of the orthoboric acid (ortho means " straight; " tliat is, *^ the " acid) and abstracting molecules 112 PHARMACEUTICAL AND MEDICAL CHEMISTRY. of water as long as possible, we get a large variety of boron acids, viz.: 1) H3B03 -H, 2) H.B,0. -H, 3) H.B.O, -H, 4) H„B,0„ -H, HBO, H.B,0. -H, H,B,0. -H, -H, H,B,0. ) H.B,0, -H, H,B.O.. -H, H,B,0. -H. H.B.O, -H, HB,0. H.B.O. -H, (Chandler H,B.O, The last acid, H^B^O,, may be looked upon as the one furnishing borax or borate of sodium by having its hy- drogen replaced by as many sodium atoms, ISTa^B^O,. The lOH^O are taken up during crystallization. H^B^O, is called the pyrohoric acid, but the term is applicable to any of the other acids obtained by abstracting water from the ortho acid by heating, pyro meaning "fire;^' that is^ in this case, an acid obtained by heating another. Pyrophosphoric acid is another example of a pyro acid. Borax, as already mentioned, is obtained principally from the borax lakes in California, where it occurs as a crystalline deposit in the mud at the bottom of the lakes. The large crystals are washed with water, dissolved and crystallized, thereby yielding an almost absolutely pure PHAEMACEUTICAL AND MEDICAL CHEMISTRY. 113 salt, which, when powdered, constitutes the powdered borax of commerce. Borax is also made from the boric acid obtained from Tuscany by fusing it with dried sodium carbonate and crystallizing the hot solution of the residue. The official borax is in colorless, shining, monoclinic prisms, somewhat efflorescent in dry air. It has an alka- line reaction, is soluble in 16 parts of cold and very soluble in boiling water, insoluble in alcohol. It is very soluble in warm glycerin and honey. Tests for the Purity of Borax. — Some of the possible im- purities in borax are metals, alkaline earths,, carbonates, sulphates and chlorides. Sulphuretted hydrogen proves the absence of metals if it does not affect a solution of borax. The alkaline earths (Ca, Ba, Sr, etc.) are precipitated, if present, by a solution of sodium carbonate. Barium and calcium, if present, are in minute quantity and dissolved in the solution of borax. When sodium carbonate is added they are converted into the less soluble carbonates of barium and calcium, which precipitate. An acid added to a solution of borax causes an ejffer- vescence if carbonate is present. (When acids come in contact with any carbonate this happens always : Na^OOg + 2HC1 = 2Na01 + H,003. The H,C03 is carbonic acid, which always resolves itself into H^O, water, and COj, carbonic acid gas. The escape of the gas produces what is known as efervescencBy by carrying with it, in its endeavor to get away, portions of the liquid, which when inter- mingled with the gas constitute /o(2?/i.) Sulphates and chlorides are detected, as in boric acid, with barium chloride and silver nitrate, respectively. 114 PHAEMACEUTICAL AN^D MEDICAL CHEMISTRY. Borax enters into many mouth and tooth washes — the honey and borax used so extensively, and made by dissolv- ing borax in honey, is an excellent form for the use of borax as a mild antacid, especially in the sprue or thrush of children. It is frequently used to whiten ointments; the yellow color which cold cream sometimes takes may be prevented by the addition of a little borax solution during its preparation. PHARMACEUTICAL AND MEDICAL CHEMISTRY. 115 Inorganic Acids. At this stage of the course the student is earnestly ad- vised to read over again very carefully all of the foregoing chapters, especially those on chemical philosophy, as he is about to enter upon the study of the acids, in which he will find the application of the principles of chemistry of constant necessity. The non-metallic elements only have thus far attracted his attention ; these mastered, the student is ready to go deeper into the details of The Study of the Acids and Salts. When treating of oxygen, we learned that an oxide is the union of oxygen with another element. We will go further now and divide the oxides into three principal groups or classes. The first class includes all those which resemble, chemically, the oxides of sodium, potassium, barium or ammonium, and others, and are called tasic oxides or alkali oxides. The second division comprises those oxides whose properties are in opposition to those of the first, and which are represented by the oxides of sul- phur, phosphorus and carbon — these are the acid oxides. The third class is represented by a single compound — water, H^O — the oxide of hydrogen. When the first two oxides combine — i.e., the basic with the acid — a salt is produced: Oxide of calcium, OaO, uniting with the acid oxide of carbon, 00^, furnishes a salt — namely, CaOOa. In like manner, for illustration, the following basic oxides uniting with acid oxides form the salts mentioned : 116 PHAKMACEUTICAL AKD MEDICAL CHEMISTRY. Basic oxides. Acid oxides. Potassium oxwt^lK.0 + SO, = K,SO„ I Sodium oxide, Barium oxide, Potassium oxide, [ Na,0 + CO, Na2C03, Potassium sulphite. Sodium carbonate. [BaO + SO. = BaS03, { ^m. ZK fi + P,0, = 2K.P0., ] P— t? This is one way of producing a salt. When the acid oxides come in contact with water (the third division of the oxides) union takes place, with the formation of acids : ^"S"1S0. + H,0 = ^S" JCO^ + H,0 ^ """oat" i^A + 3H,0 = Nitric oxide. Nitric |n.O, + H,0 Acids. H.SO3, H2CO3 , 2H3P0., I ,,i,. 2HNO3, I ^^ Sulphurous acid. Carbonic acid. Phosphoric Acids are of two principal kinds — the Jiydracids, those containing no oxygen, and the oxyacids, those containing oxygen and represented by the above. A third division is sometimes made, including those represented by arsenious acid, ASgOj. The latter had better be termed anhydrides, because they contain no hydrogen, and hydrogen is an essential constituent of all acids. The word acid is a mis- nomer chemically for all substances that do not contain replaceable hydrogen in their base. We have learned that one way of producing salts is by uniting a basic with an acid oxide; another is by replacing PHARMACEUTICAL AITD MEDICAL CHEMISTRY. 117 the hydrogen in acids with metals, thus (Free hydrogen is not the by-product in each case, but is assumed to be to illustrate the lessen in hand) : Acid. Metal. Salt. 2HN0;, [ + S^^^^"^' ^^« ' =1 ^^^^^' ' + H^ ''''^'''"'' Hydrgjhloric, | _j_ ^^^^^ 2n,, = j ZnCl, , Chloride zinc, + And a third by replacing the hydrogen with basic oxides, thus: Acid. Basic oxide. Salt. 3HNO3 + Sodium oxide, Na^O, = SNaNOs + H^O. 2HC1 + Zinc oxide, ZnO, = ZnCU + H2O. H2SO4 + Iron oxide; FeO, = FeS04 + H2O. 2H3PO4 + Calcium oxide, 3CaO, = Ca3(P04)2 + SH^O. The three ways of making salts, then, are : 1, by uniting basic and acid oxides; 2, by uniting metals with acids; and 3, by uniting basic oxides with acids. In the last-mentioned method it will be noticed that the oxide of hydrogen — water — is liberated, and that only the acid oxides in the respective acids do the real work for the acids — i.e., oxyacids resolve themselves during the union into their acid oxides and water : 2HNO3 = -Nfi, + H,0 H,SO, = SO3 + H,0 2H3PO, = P,0, + 3H,0, etc. Acids are salts. They are a particular group, and the oxyacids always contain the elements of an acid oxide and hydrogen oxide. Many of them possess in a marked degree the properties to which the term " acid " is applied, such 118 PHARMACEUTICAL AND MEDICAL CHEMISTRY. ' as sour taste, solubility in water, corrosive action, power of reddening vegetable colors, and neutralizing alkalies or alkaline bases, basic oxides. The most characteristic prop- erty of the acids is their power of exchanging their hydro- gen for metals or basic oxides to form salts — basic oxides are often spoken of as bases — as shown above. Tbus when sulphuric acid, which contains hydrogen, sulphur and oxy- gen, comes in contact with a metal — zinc, for example — the hydrogen is replaced by the zinc, and that which was hydrogen sulphate becomes zinc sulphate, the hydrogen being liberated. The same will happen when a base comes in contact with an acid, only that the hydrogen which is set free unites with the oxygen combined with the metal, and forms water. It must be borne in mind by the student that these changes all take place according to the laws of chemical combination. The student should also refresh his memory regarding, the atomicity, number of bonds, etc., of all the elements. Salts, and therefore acids, are usually spoken of as con- taining a hase and a radical; in H^SO^, for instance, the H^ is the base and SO^ the radical; in NaNOg the Na is the base and NO3 the radical. (The term base should not be confounded with the term as used before.) It would be more correct to speak of an acichdous radical, and a hasyl- ous radical as constituting an acid — that is, it would be more rational, as an acid and a hase when united form a salt, and both may be looked upon as radicals or roots. In writing salts the base, as well as the radical, has a certain number of bonds, whether each consists of only one element or of more. In the following there is only one element in each, the base and the radical, and consequently PHARMACEUTICAL Al^D MEDICAL CHEMISTRY. 119 the base and radical haye each as many bonds as their respective elements : Radical. Chloride' Bromide' Iodide' Chloride" Base. Sodium' Hydrogen' Potassium' Calcium" NaCl HBr KI CaCL In the following there is one element in the base and more than one in the radical. The elements in the radical form a group which may be looked upon as behaving as a single element does and together having a certain number of free bonds. Base. Radical. HN03 H' (NO3)' nitric acid ) H,SO, H/' (SO.)" sulphuric acid f Inorganic. H3PO, H3"' (PO.)'" phosphoric acid ) HC.HaO, H" (0,H30,)" acetic acid ^ H.C,H,0, H/' (O.H^OJ" tartaric acid ^ Organic. HsCeH.O, H3"' (C.H,0,)"' citric acid The (NO )' has one bond, the (SOJ" two, and the (POJ'" three, etc.; these radicals interchange in the dif- ferent combinations without altering their relative propor- tion or position. The student should study the quanti- valence of the above-mentioned acid radicals and commit them to memory. In order to make salts from these or other acids it is only necessary to replace the hydrogen with an equivalent quantity of some metal, and to remem- ber that the hydrogen alone can be replaced. Bases, like radicals, may consist of more than one element : 120 PHARMACEUTICAL AND MEDICAL CHEMISTRY. Base. Radical. Sodium bicarbonate (NaH)" (CO3)" NaHCOs Potassium bitrartate (KH)" (C4H4O6)" KHC4H4O, Sodio-potassic tartrate (KNa)" (C4H4O6)" K]SraC4H408 Acid calcium phosphate (CaH)"' (PO4)'" CaHPO* These salts are known as acid or bi-salts when they con- tain some unreplaced hydrogen, and as double salts when the hydrogen of a dibasic or tribasic acid is replaced by two metals, as in Rochelle salt, KNaO^H^Og , etc. Acids having one replaceable hydrogen atom are called mono- basic, as HOI, HNO3 ; when they contain two replaceable atoms, dibasic, as H^SO^ ; when three, tribasic, etc. The same terms apply to salts. In writing the formulas for salts or acids, the base occu- pies the left and the radical the right. Thus, sulphate of sodium is written Na^SO^ , and not SO^Na^ , or O^SNa^. The atoms occupy a definite position in their arrangement in the molecule. We may express this relative and constant position of the atoms by means of Graphic Formulas. When we write H2SO4 we employ a rational formula — i.e., rational, because it shows us in a rational way at a glance how many hydrogen atoms are replaceable and how many bonds the radical has, etc. If we should write O4SH2 , that would imply that sulphuric acid contains 4 atoms of oxygen, 1 of sulphur and 2 of hydrogen, but it would tell us nothing further than that. The following graphic formulas of the principal acids should be remembered by the student: PHARMACEUTICAL Ai^D MEDICAL CHEMISTRY. 121 H,SO, = )S C HCl = H~C1 HNO3 = H-O-N ^ H3P0,= H-0->P = This shows the number of bonds of each element to be satisfied or united with the bond of some other element, and the positions of the atoms in the molecules. In H^SO^, for example, the S has six bonds distributed among the three oxygen atoms, each of which atoms has two bonds. The hydrogen always occupies the left-hand position, and in the case of oxyacids is ahuays united to oxygen. Graphic formulas of salts are written exactly as those of the acids are, except that the metals occupy the place of the hydrogen. NajSO^ would be written graphically thus : Na-O. ^ Na-O/ "=" 0a3(P0j2 from two molecules of phosphoric acid, n3P0,: H-0\ ^_ .Ov H-0 Oa< H-0-^p=0 Oa<^-^P=0 H-0 0, Calcium being a diad and phosphoric radical a triad, we must take three of the former and two of the latter to satisfy all bonds. 122 PHARMACEUTICAL AND MEDICAL CHEMISTRY. It was at one time supposed that all acids contain oxy- gen, and the element known as oxygen was so termed be- cause of that belief, the term meaning acid generator. We are acquainted at present, however, with many bodies which exhibit all the properties of acids and yet contain no oxygen. The combinations of the halogen elements with hydrogen are such bodies — hydrochloric acid, HCl; hydrobromic, HBr; hydriodic, HI, etc. These are the hydracids. The proportions of the two elements in each of these acids cannot vary as the elements do in the oxyacids. As illustrations of varying quantities of elements in some of the latter, the following may serve : II2SO3, hydrogen sulphite or sulphurous acid. H^SO^ , hydrogen sulphate or sulphuric acid. HNO2 , hydrogen nitrite or nitrous acid. HNO3 , hydrogen nitrate or nitric acid. The oxygen varies in quantity and determines the names of the acids and the salts obtained from them. The stu- dent is advised here to read over again what was said on chemical nomenclature and writing of salts elsewhere. The inorganic acids are never made by the pharmacist; their manufacture on the large scale is an important and one of the most extensive branches of the chemical in- dustry. The manufacturing chemists send the acids into the markets usually in three qualities, the common or commercial f used for all else than for medicinal or ana- lytical purposes; the medicinally 'pure, abbreviated if.P., used for internal administration, and the chemically j^ure, abbreviated C.P., intended for analytical purposes where absolute purity is essential. The latter is almost wholly l>HARMACEUTiCAL AND MEDICAL CHEMISTRY. 123 used in pharmacy for prescription use, and in making preparations containing acids, since it is nearly as cheap as the medicinally pure. One of the most difficult and expensive parts of the manufacture of the acids is the removal of impurities, and for purposes in which the im- purities are of no consequence the process of purification is wholly omitted, yielding the common or commercial acids. Very often the presence of minute traces of some kinds of impurities will not affect the value of the acids for medici- nal purposes, so that the traces are not removed, but only the greater bulk of the impurities, yielding acids which answer the purposes of medicine very well, but which are yet unfit for delicate analytical uses. For the latter pur- pose all traces of impurities must be removed, and to do that requires more skill and expense than to free the com- mon acids from the greater bulk of their impurities. In most cases it is not possible to remove all impurities at once from the crude acid, hence the amount of work is greater for the production of the medicinally pure than for the common. The same is true of the chemically pure over the medicinally pure. At one time the cost of the production of the chemically pure was much greater than that of the medicinally pure, but of late, improvements in the methods of purification have brought the price of the former so near that of the latter that pharmacists now usually purchase the C.P. The labels should not satisfy the conscientious pharma- cist as to the purity of the acid which he purchases. It is an easy matter to apply the simple tests given in the Phar- macopoeia for the detection of impurities. The mineral acids should never be kept in any other than glass-stop- pered bottles ] cork is acted upon and quickly contami- 124 PHARMACEUTICAL AKD KEDICAL CHEMISTRY. nates the acid. A special bottle, called acid-bottle, usually made of green glass and very strong, is used as acid con- tainer. The neck and stopper are usually well ground and fit very accurately^ for which reason it is often difficult to extract the glass stopper. To do this successfully, all that is usually necessary is to remove the wax or lute from around the stopper and strike the side of the stopper gently with the wooden handle of a spatula, at the same time pulling upward on the stopper. If this will not accomplish the purpose, the stopper may be wedged in between two closet-doors closing against each other, press- ing gently inward and cautiously turning the bottle. Great care should he exercised not to break the neck of the bottle, else damage to clothing and fixtures will result from the spilling of the acid. Should this means not avail, the neck of the bottle may be gently turned in the flame of a Bunsen burner for a moment. The heat expands the neck first, and the stopper may be removed before the heat is communicated to it. The utmost care must be observed in handling the strong acids; some of them — for instance, nitric — may pro- duce fire if poured or spilled upon organic bodies. They are all very corrosive and caustic, attacking and destroying everything they come in contact with. It is always best to have an alkali on hand, in case it becomes necessary to neutralize them; ammonia-water neutralizes most quickly, bicarbonate of sodium or chalk will answer well also. The solutions of soda and potassa neutralize well, but they, too, are very caustic and may do damage if used in excess. Antidotes to Mineral Acids. — The acids are all very powerful poisons and produce the most painful and dan- PHARMACEUTICAL Ai^D MEDICAL CHEMISTRY. 125 gerous effects on the mucous membrane and stomach. If they are taken at any time accidentally, large draughts of alkaline liquids that do not corrode should be given, fol- lowed with oil. Sodium bicarbonate made into a milk with water should be given slowly, if at hand, or any other chemical that will neutralize the acid without itself being injurious. The 00^ which is disengaged usually escapes through the oesophagus and mouth, and because of the dis- engagement of the gas where carbonates are given the lat- ter should not be administered too copiously, but rather in small quantities frequently. The gas may cause undue dis- tention and distress if liberated too suddenly. Soap is an excellent antidote, given in strong solution. The oil, which should follow, obtunds the action of the acid upon the delicate membranes. Medical Properties of the Inorganic Acids. — Externally applied the inorganic acids are very corrosive, and should be used with great care. For internal administration they are usually given in a diluted form for their refrigerant and tonic properties. They are apt to injure the dental struc- ture by attacking and dissolving the substance of the teeth, and for this reason should always be taken in plenty of water and through a glass tube in such a way that they do not come in contact with the teeth. Sulphuric Acid. We know by this time that an acid, aside from its char- acteristic physical properties, is a chemical compound containing hydrogen as its base, which hydrogen is replace- able by metals. In the same way that we can replace this hydrogen in the acids by metals and produce salts, we can, 126 PHAKMACEUTICAL AITD MEDICAL CHEMISTRY. reversely, replace the metals in salts by hydrogen and obtain the acids. This will become clearer, perhaps, by illustration. If we treat the salt nitrate of sodium, NaNOg, with sul- phuric acid, H2SO4, two things happen — the H, is replaced by the Na, two atoms of which are taken, and the two atoms of sodium are replaced by an equivalent of hydrogen, Hj. In other words, there will be simply an interchange of bases; the H^SO^ forms the salt Na^SO^, sulphate of sodium, and the nitrate of sodium becomes HNOg, nitric acid : H,SO, + 2]S^aN03 = 2HNO3 + Na.SO,. In this manner is nitric acid made. In fact, all of the acids may be made in this way, by bringing an acid in contact with a salt containing the corresponding acid radical. The following acids, made by acting on the correspond- ing salts with some other acid, may be cited as examples : Acids. Salts. Acids. Salts. Hydrochloric, from H,SO, + 2^01 = 2HC1 + Na.SO, Hydrocyanic, '' HCl + AgOy = HCy (or HON) + AgOl. Acetic, HNO3 + KCJIfl, = HC.HgO, + KNO3 In the above reactions the Na^SO^, AgCl and KNO3 are by-products and the acid the primary product. The question may be put by the student : Are all acids made from some other acid ? Must there not be some acid or acids (the source of all other acids) which is or are not made from some other acid? The logical answer would be that if all the acids are made from other acids, very soon there would be no acids at all, and that therefore some acid must have its source in something which is not an acid. PHARMACEUTICAL AN"D MEDICAL CHEMISTRY. 127 The latter is true of sulphuric acid, which is the most im- portant of all the inorganic acids, principally because it is the source of many other acids, and is not itself made from another acid. The student will better understand this as we go on. The method of manufacturing sulphuric acid to-day is essentially, with some modifications, the same as that experimentally employed by Lavoisier in 1774 and 1775. Preparation. — By burning sulphur in air it takes up oxygen and becomes the oxide of sulphur, SO^. The heat produced is utilized in suitable chambers to decompose sodium nitrate ; this decomposition yields oxygen, which is taken up by the SO^ to form SO3. The SO3 fumes, coming in contact with watery vapors, unite with them, producing sulphuric acid, H^SO^, in a diluted form. The following equations will serve to demonstrate this more clearly. (1.) S + 0, (Air) == SO,. (2.) 2NaN03 -f heat = Na,0 + N^O, + 30, or (2a.) 2Na]Sr03 + H,SO, = Na.SO, + 2HNO3. (26.) 2HNO3 + heat = H,0 + N,0, + 30. (3.) N,0, + 0, (Air) = N,0, (4.) 2S0, + N,0, = 2SO3 + N,0,. (5.) SO3 -f H,0 (Steam) = H,SO,. If the SO2 is brought in contact with steam HjS03, sulphurous acid, will result: SO, + H,0 = H,S03. To get the higher form of oxidation, the nitrate of so- 128 PHAEMACEUTICAL AND MEDICAL CHEMISTRY. dium is decomposed, the products of decomposition being, besides oxygen and water, an oxide of nitrogen, N^O^, which has the peculiar property of abstracting oxygen from the air to form N^O^ and of giving this up again to the SO3 to make SO3, becoming itself again N^O,, when it is again ready to abstract a fresh supply of oxygen from the air. It thus acts as a carrier of oxygen from the air to the SO2, and is generated only in the beginning of the process. Instead of using sulphur, sulphide of iron, FeS, is often employed. In this process it is not necessary that any other acid be employed ; it furnishes the acid from which nearly all others are made — it is the starting point in the acid-manufacturing industry. The fumes of SO^ are passed into large leaden chambers, where they come in contact with the N^O^, and then with steam. The acid thus produced collects at the bottom of the chamber, and is not very concentrated. It forms one of the varieties of acid found in the market, and known as chamber acid, of a specific gravity ranging from 1.40 to 1.50. When removed to pans, also of lead, and boiled down to a specific gi-avity of about 1.70, it constitutes pan acid. At that density it begins to act on the lead, the dilute acid having no effect on that metal. In order to further concentrate it, it is necessary to distil off the water in porcelain or platinum or glass retorts. The sulphate of sodium, which is the by-product, is re- crystallized and sold as Glauber's salt. Sulphuric acid thus prepared and purified is an oily liquid of a specific gravity of 1.835, colorless, without odor, of a strongly acid reaction, and is very caustic and corrosive, soluble in alcohol and water with the evolution of heat. If heated to a high PHAEMACBIJTICAL AND MEDICAL CHEMISTRY. 129 degree it volatilizes ; in contact with organic matter it becomes black, carbonizing the body by uniting with the other elements and setting the carbon free. In the crude acid there are present a number of impuri- ties, which through incomplete methods of purification are often found in smaller quantity in the medicinal and puri- fied acids. To guard against the presence of impurities the pharmacist should always examine the sulphuric acid for lead, copper, iron and arsenic, nitric, hydrochloric and sul- phurous acids. In this country the acid is usually made from sulphur, but that made abroad is from sulphides of iron, or iron pyrites, which are always associated with arsenic. The latter, because it is volatile, is usually present in the crude acid made from the iron pyrites, and is a dan- gerous contamination. Tests for Impurities in Sulphuric Acid. — The following tests should be memorized by the student, because they are for substances which are not present in sulphuric acid only, but which may be found in the acids prepared directly or indirectly from sulphuric acid. To detect lead, a portion of the acid should be poured into four volumes of alcohol — a precipitate within an hour indicates the presence of lead. For iron, when diluted with 10 volumes of water, the addition of excess of water of ammonia will give a brownish precipitate. Copper, if present, gives a blue color with excess of water of ammonia. Arsenic may be detected by mixing 1 cc. of a mixture of 1 volume H^SO^ and 2 of water, with 1 cc. test-solution stannous chloride, and adding a small piece of pure tin-foil 130 PHARMACEUTICAL AN^D MEDICAL CHEMISTRY. — if a coloration appears within one hour arsenic is present. The acid upon supersaturation with ammonia should leave no fixed residue upon evaporation and ignition; this would indicate the absence of non-volatile impurities. Nitric acid, if present, will produce a brownish or red- dish zone between a layer of sulphuric acid, in a test-tube, and one of a freshly-prepared solution of ferrous sulphate. Hydrochloric acid, if present, gives ^ precipitate with solution of sulphate of silver. Usfes and Properties of Sulphuric Acid. — The employment of this acid is more extensive than that of any other acid. It is the strongest and most powerful of the official acids, decomposing salts with a marked chemical energy. It is the source of most acids and sulphates, and, in a diluted form, is a valuable medicament. It is sometimes employed externally as an escharotic, but its use for this purpose is limited, owing to its tendency to spread on the skin and to affect the surrounding tissue. When accidentally dropped on the skin its caustic effect may be neutralized by profuse use of diluted water of ammonia, or sodium bicarbonate, or calcined magnesia. In manipulating sulphuric acid it should be particularly remembered that it evolves a great amount of heat when mixed with other liquids, and that it should ahoays he poured i7ito the other liquid, and very slowly, to prevent the vessel from breaking by the sudden expansion caused by the rapid rise of temperature. The sulphuric acid of the U. S. Pharmacopoeia is a liquid composed of 92.5 per cent of absolute H^SO^ by weight and 7.5 per cent of water. It should be kept in glass- stoppered bottles. It is colorless, of oily or syrupy consist- PHARMACEUTICAL AND MEDICAL CHEMISTRY. 131 ence, miscible with water and alcohol. It has a specific gravity of 1.835 at 15° C, and is vaporized when heated on platinum-foil Diluted Sulphuric Acid contains 10 per cent of absolute acid, and is made by pour- ing the acid into water, slowly and carefully, stirring mean- while. It has the same properties as the stronger acid, except those which depend upon the strength or concen- tration of the latter. Its use is chiefly for internal admin- istration or for dissolving quinine when quinine is desired in the liquid form. Aromatic Sulphuric Acid. This is a more grateful preparation for the internal use of sulphuric acid. It contains 20 per cent of absolute acid in alcohol, combined with the aromatics ginger and cinna- mon. Tincture of ginger and oil of cinnamon are employed by the U. S. P. of 1890. The 1870 Pharmacopoeia em- ployed the crude drugs, instead of these their preparations, and the finished product contained, as a result, a little tannic acid. The aromatic, as the dilute acid, is often employed for preparing solution of quinine ; but the presence of tan- nic acid in the 1870 Pharmacopoeia product frequently caused a turbidity, from the fact that tannic acid precipi- tates alkaloids, quinine in this case. To obviate this, the Committee of Revision of the Pharmacopoeia in 1880 sub- stituted tincture of ginger for the powdered root, and oil of cinnamon for the powdered bark, as mentioned above. Fuming Sulphuric Acid. — The sulphuric acid described above is the ordinary acid of commerce. There is another variety known as Fuming Sulphuric Acid, or Nordhausen acid, so called because it constantly emits fumes when ex- 132 PHAKMACEUTICAL AI5"D MEDICAL CHEMISTEY. posed to the air; and because it was first made at a place called Nordhausen, in Saxony, Germany. This acid is made by distilling, in large stone retorts heated to redness, the or- dinary sulphate of iron previously deprived of its water of crystallization by heat. Polishing-rouge remains in the retort, and the fuming acid distils over. It is supposed to be 11,^820, or H^SO^SOg — that is, a solution of SO3 fumes in H2SO4. The SO3 fumes are constantly given ofC. Solid Sulphuric Acid is the anhydride, SO3, now to be found in a solid condition in the market is soldered boxes of tinned sheet-iron. When moisture is wholly excluded this acid has little or no action on metals. Sulphurous Acid. The termination of the first word in this title indicates that the acid is a lower sulphur acid than sulphuric acid; it denotes that it is the next lower. If we were to take one atom of oxygen away from sulphuric acid, H^SO^, the acid H2SO3 would result, and in practice that is the precise way in which sulphurous acid is made. Preparation. — Sulphuric acid is mixed with powdered charcoal and heated in a retort or large fiask, and the gen- erated gases passed through two bottles containing water, the last of which will contain the sulphurous acid sought. The first bottle washes the gas. The charcoal or carbon acts on the sulphuric acid and takes away one atom of oxy- gen from each of two molecules of acid. The H^SOg which is left splits up into H^O and SO^; the SO^ and 00^ pass through the water in the bottles, saturating the water with PHARMACEUTICAL AKD MEDICAL CHEMISTRY. 133 SO.^, the CO2 escaping. A third bottle containing a solu- tion of carbonate of sodium is sometimes employed to retain any gas that may not be absorbed by the distilled water in the other bottles. The solution of SO^ in the second bottle constitutes the product which the process was intended to furnish, namely H^SOg. The first bottle contains the same but mixed with other bodies, and is rejected. The steps may be illustrate- by the following equations : 1. 2H,S0, + = CO, + 2H,S03. 2. H^SOg + heat = H,0 + SO,. 3. SO,, cold, + H,0 =: H,S03. The strength of the acid is 6. 4 per cent sulphurous acid gas, SO,. The solution of sodium carbonate absorbs the excess of SO, which the water will not absorb : ]sra2C03 + SO, = Na3S03 + CO,, liberating more carbonic acid gas. Properties. — This solution of sulphur dioxide is a color- less liquid of a sp. gr. not less than 1.035, strongly acid reaction, and an odor resembling burning sulphur. When heated it completely volatilizes. Its bleaching properties are pronounced, and depend upon the SO, which it contains. It is rarely used internally, its salts being preferred. Dose, from 3 to 30 minims (0.185 to 1.85 cc.) or more, with water. Its chief property is anti-parasitic, destroying microscopic organisms, for which reason it may be employed when an anti-ferment is desired. Its employment to prevent fer- mentation is manifold, that to check fermentation of cider at a certain stage being very extensive. 134 PHARMACEUTICAL AND MEDICAL CHEMISTRY. Nitric Acid. The acid next in importance to sulphuric acid is proba- bly nitric acid, HNO3, a combination of the highest oxide of nitrogen, N^O^, with water. It may be looked upon as consisting of 2HNO3 = H^O -\- N^O^. l^itrous acid con- tains in two molecules the same amount of water united with the next lower, or nitrous, oxide, li^fl^ — 2HNO2 = Preparation. — Nitric acid is made on a large scale by acting with sulphuric acid on either sodium or potassium nitrate contained in a retort, heating carefully to distilla- tion and collecting the distillate in well-cooled receivers. Equal weights of the acid, and nitrate in case of the potassium salt, are usually employed, but in some processes on a large scale more of the nitrate and less of the acid are preferably employed. These two reactions may be illustrated by equations, and are a means of illustrating The Functions and Uses of Equations. An equation tells not only what will be produced when two bodies capable of uniting chemically are brought in contact, but it tells also how much by weight of each body must be employed, or, on the other hand, how much by weight of each of the resulting compounds will be formed, or how much of each of the reacting bodies must be used to produce a certain weight of one or more of the resulting compounds. The first of these reactions is brought about when we take weights represented by one molecule of each, acid and salt, as follows: PHARMACEUTICAL AND MEDICAL CHEMISTRY. 135 KNO3 + H,SO, = KHSO, + HNO3, and the second, when twice as much of the nitrate is em- ployed: 2KNO3 + H,SO, = K,SO, + 2HNO3. In the first reaction one molecule of the nitrate is used and one molecule of nitric acid is produced, besides an acid sulphate of potassium, in which there is still some un- replaced hydrogen. In the second case two molecules of nitrate of potassium are used and two of nitric acid are produced, with the formation of a neutral sulphate of po- tassium as a by-product. The first process is employed when an exceedingly concentrated acid is not demanded; the acid sulphate, .too, is more easily removed from the retort than the neutral sulphate, which often forms a very hard cake. Now, to return to equations and their functions, we find that a symlol represents, among other things, the weight of the atom, or atomic lueight ; thus, K means, besides other things, that the potassium atom is 39 times heavier than the hydrogen atom. The formula of a compound represents, besides other things, the weight of the molecule — that is, the sum of its atomic weights; thus, KNO3 means that the weight of the molecule is 39 for K, + 14 for N, -|- 48 for O3 — 101. In the same way we find that the mo- lecular weight of sulphuric acid is 98. Now, these figures denote the proportion in which the bodies'whose molecular weights they represent will unite with each other, accord- ing to the first equation : 101 4- 98 = 136 + 63. KNO3 -f H,SO, = KHSO, + HNO3. That means if 101 of nitrate of potassium and 98 of acid 136 PHARMACEUTICAL AKD MEDICAL CHEMISTRY. be used, 136 of acid sulphate and 63 of nitric acid will be produced. The figures denote relative proportions by weight. They may mean grammes, ounces or pounds, or any other de- nomination of weight, but they must all represent one Icind of weight division. According to the second equation, different proportions of nitrate and acid would enter the reaction, as follows : 202 + 98 = 174 + 126. 2KNO3 + H,SO, = K,SO, + 2HNO3. In the chapter on chemical philosophy we learned that elements united with each other in definite chemical pro- portions, and that sometimes the proportion of one ele- ment is fixed, while the other increases in definite multiple proportions. Thus in CO and CO^ the C is fixed or con- stant, while the increased in the case of 00, in multiple proportion of 16 — namely, twice 16, etc. This is not true of elements alone, but of compounds as well. In the above two reactions the acid is constant, but the KNO3 may be used in more than one proportion, subject to the law that it must be exactly a multiple proportion, and no more nor less than such multiple proportion expresses, the proportion being always understood to be taken by weight. So far we have learned that if we express the reactions between two or more bodies by equations, we can find out by employing the molecular weights of the bodies entering the change how much of each of those bodies must be em- ployed without causing a loss of either. We may now proceed a step further in our chemical mathematics. Writing an equation as we did above, we can tell from it how much of the bodies entering the reac- PHARMACEUTICAL AITD MEDICAL CHEMISTRY. 137 tion must be used to produce a desired amount of the l^roduct. Thus, supposing it was our intention to make 100 pounds of nitric acid. From the above equation we know that in order to produce 63 pounds we must employ 101 pounds of the potassium salt and 98 pounds of sulphuric acid, pro- viding both were absolute — that is, 100 per cent. The proportions necessary for a given quantity may be calcu- lated by the rule of three thus: If 63 pounds metric acid require 101 pounds of nitrate, then 100 pounds would re- quire X quantity; or, as 63 is to 100, so must 101 be to the unknown quantity: 63 : 100 :: 101 \ x. 63)10100(160.31+ = number of pounds of the nitrate necessary to produce 100 pounds nitric acid. 63 : 100 :: 98 : a;. 63)9800(155.55+ = number of pounds of sulphuric acid necessary to make 100 pounds of nitric acid. When we say that, according to the equation, 98 pounds of sulphuric acid must be employed, we mean 100 per cent acid. If the acid were only 96 per cent absolute acid, we would need to employ of it more than 98 pounds. The weight of the 96 per cent acid to be employed would be ascertained in this wise, simply : 96 per cent : 100 per cent :: 98 pounds : 102.2 pounds. Ansiver. — 102.2 pounds of the 96 per cent, sulphuric acid, therefore, contains the necessary 98 pounds of abso- lute acid. Properties of Nitric Acid. — This acid is, next to nitro 138 PHAKMACEUTICAL AKD MEDICAL CHEMISTRY. hydrochloric, the most caustic of all acids. It is extremely corrosive, and has, a powerful oxidizing capacity, greater than any other body. It was made as early as the thir- teenth century, and was called aqua fortis by the ancients. It is now called nitric acid because made from nitrey the common name for potassium nitrate. Nitric acid is known also by the name azotic acid. By heat it is wholly volatilized; a residue would indicate presence of fixed impurities. It usually has a straw-yellow color, due to the presence of a lower acid of nitrogen, but when perfectly pure it is wholly colorless. Its action upon living tissue is that of a strong caustic ; it stains the skin an indelible yellow color, producing what some call xantho- proteic acid. The most characteristic property of nitric acid is its oxidizing powers; it oxidizes phosphorus, sul- phur, etc., and dissolves most of the metals; with salifiable bases it forms nitrates. It enters into the preparation of nitrohydrochloric acid, the only acid that will dissolve gold. In its action on many organic bodies its chemical affinity exerts itself with such violence as to produce very often enough heat to ignite the surrounding bodies. Its oxidizing properties depend on the evolution of nascent oxygen in its decomposition: 2HNO3 decomposes into H,0 + N,0, + 30. The specific gravity of the official acid is 1.414, corresponding to a strength of 68 per cent absolute acid; but the acid usually furnished by the manu- facturing chemist is seldom of that strength, being more often of a specific gravity of 1.35. Stress should always be laid on the importance of employing the 1.414 specific gravity acid in making the U. S. P. preparations, as that was used in the calculations for the preparations into which nitric acid enters. PHARMACEUTICAL AND MEDICAL CHEMISTRY. 139 Impurities in Nitric Acid. — All the impurities that may- be found in sulphuric acid may be looked for with the ap- propriate tests given under sulphuric acid. In addition, bromic and iodic acids may be present, which may have been in the nitrate as iodate and bromate. If the acid be diluted and shaken with a few drops of chloroform, the latter should not become colored — this would indicate the absence of iodine or bromine. The introduction of a small piece of pure zinc produces no color in the absence of iodic or bromic acids. Uses in Pharmacy and Medicine. — Nitric acid largely- diluted is the official dilute acid, which is given in doses of 5 to 15 minims (0.30 to 0.90 cc.) as a tonic and astringent. In its undiluted form it is used as an escharotic for navus, warts, etc. Dilute Nitric Acid Has the same properties and uses as the strong, excepting those dependmg on greater concentration. It contains 10 per cent of absolute acid. Hydrochloric Acid. In pharmaceutical nomenclature there is a certain spe- cific meaning implied by the titles occurring in the Phar- macopoeia, distinct altogether from the ordinary or usual meaning attached to those words. Thus the title " Acidum Hydrochloricum" or its English equivalent, ^^ Hydrochloric Acid," means the particular body described in the U. S. P. under this head, and no other. There are other kinds of hydrochloric acids, differing not in the essential of contain- ing the elements hydrogen and chlorine, but in strength, in the presence of impurities and contaminations, etc. 140 PHARMACEUTICAL AN"D MEDICAL CHEMISTEY. The hydrochloric acid, therefore, that we are to consider is " a liquid composed of 31.9 per cent of absolute acid and 68.1 per cent of water,'' as described in the Pharmacopoeia. It is at times called "muriatic acid," "'spirit of salt," "marine spirit," "marine acid," the latter terms referring to its source, common salt from the sea. Properties. — The pure acid is colorless; has a penetrat- ing, suffocating odor and extremely caustic taste, miscible with water and alcohol in all proportions. It has a specific gravity of 1.16, but may be concentrated to increase its density up to 1.22. Heat will completely volatilize it, and even at ordinary temperatures it slov/ly vaporizes, forming white fumes of ammonium chloride by combining with the ammonia in the air. This is a reliable test for either hydrochloric acid or ammonia; if a glass rod be dipped into ammonia water and held near the acid, the white fumes immediately appear. Ammonia, NH3 + HOI = am- monium chloride, NH^Cl. When very concentrated the acid blackens organic matter, as does sulphuric acid. The acid is not a liquid, but a gas, HCl, the only known combination of hydrogen and chlorine. When dissolved in water to the extent of 31.9 per cent, it constitutes the official acid. The acid and any of its salts form with solution of silver nitrate a characteristic white precipitate of chloride of silver, which is readily soluble in ammonia, but reprecipi- tated if the ammonia is again neutralized with an acid. Hydrochloric acid has strong chemical properties, com- bines with the alkalies and alkaloids to form salts, chlorides, and dissolves a number of the metals. Preparation. — If common salt, chloride of sodium, be mixed with sulphuric acid and the mixture distilled, hydro- PHARMACEUTICAL AKD MEDICAL CHEMISTRY. 141 chloric acid or the chloride of hydrogen will result. Un- less the salt and acid are pure the product will be con- taminated. On a large scale a very impure acid is obtained by the employment of common sulphuric acid and distilling from iron retorts. By far the greater part of the hydrochloric acid of the market is not made directly, but is a by-product in the manufacture of sodium sulphate in the process of convert- ing the chloride of sodium into carbonate and hydroxide, or into "soda-ash," as the mixture is called. Chloride of sodium is the source of most of the other sodium salts, which latter, however, cannot be made directly from the chloride. The chloride is first changed into the carbonate, from which most of the other sodium salts are then made with facility. To convert the chloride into the carbonate, Leblanc^s process is one means, and in the first stage of the process hydrochloric acid is a by-product : 2]^aCl 4- H^SO, = 2HC1 + Na.SO,. Na.SO, + CaC03 + 30, = Na,003 + CaS -f 400. The salt NaOl reacts with the sulphuric acid and produces hydrochloric acid, which is in a gaseous condition, and is made to pass through towers, down which water trickles to dissolve the gas, and the acid then passes out as a relatively concentrated product. To produce a pure acid, pure fused chloride of sodium and pure sulphuric acid are employed, and the gas passed into distilled water contained in a series of bottles. The following reactions illustrate the chemistry of the process. Here, as in nitric acid, two proportions may be employed : 58.5 98 120 36.5. NaOl 4- H,SO, = NaHSO, + HOI 142 PHARMACEUTICAL AND MEDICAL CHEMISTRY. or, 117 98 142 73 2NaCl + H,SO, = Na,SO, + 2HC1; The figures denote the molecular proportions of NaCl and H2SO4 to be employed, as fully explained under sul- phuric acid. The first process yields acid sulphate of sodium, which is more easily removed from the retort than the neutral sulphate obtained in the first reaction. The acid sulphate may be further employed with more NaCl to yield HCl: NaHSO, + NaOl = Na.SO, + HCl. Converting the sulphuric acid first into the acid sulphate, and that into the normal or neutral, amounts to the same thing as does the second reaction above. Impurities. — As in nitric acid, so in hydrochloric acid may be present such impurities as are in the sulphuric acid from which it is made. The tests given under sulphuric acid may be here applied for these impurities. Additional impurities or contaminations may be chlorine and sulphuric acid. Chlorine will be recognized by liberating the iodine in a solution of iodide of potassium, the acid having pre- viously been diluted with five or six volumes of water. The iodine will be recognized by the familiar starch-test — that is, turning blue with starch-paste. If chloride of barium solution produces a precipitate when added to the dilute acid, the presence of sulphuric acid would be indi- cated. The following reactions illustrate the two tests just given: 1. (a) 3KI + 01, = 2KC1 + I,; (b) I, + 10C.H„0. (starch) = 3(C,H,„0,),I, blue iodide of starch. PHARMACEUTICAL AKD MEDICAL CHEMISTRY. 143 2. BaCl, + H,SO, = 2H01 -f BaSO,, heavy white insolu- ble sulphate of barium. (It is doubted by many that iodide of starch is a definite chemical compound. The Pharmacopoeia of 1880 evidently did not recognize it as such, to judge from the name it gave to it — iodized starch.) The commercial acid is full of many kinds of impurities, the most injurious being" sulphurous acid, which is present sometimes to the extent of 10 per cent. The pharmacist should never sell it except for use in the arts. Uses of Hydrochloric Acid. — This acid is used primarily for the preparation of the dilute acid and the nitrohydro- chloric acid, but also largely as a medicine for its tonic, refrigerant and antiseptic properties. The dose is about five minims, largely diluted. In concentrated form it is a caustic, though not so powerful as nitric acid. It is fre- quently employed to dissolve alkaloids, iron and zinc in making the respective solutions of the Pharmacopoeia, and also aids in dissolving the arsenic in the ofiicial solu- tion of arsenous acid. With black oxide of manganese it yields the official chlorine-water, and by dissolving out the phosphate of calcium from animal charcoal it produces the purified animal charcoal. With cyanide of silver it gives diluted hydrocyanic acid. Antidote. — Hydrochloric acid is an irritant poison, pro- ducing a characteristic fiery redness of the tongue, black- ness of the lips and violent gastric pains. The best anti- dote is calcined magnesia made into a milk with water, given in copious draughts. Other mildly alkaline solutions, as soap, etc., are also efficient. Demulcent and bland drinks should follow. 144 PHARMACEUTICAL AlS^D MEDICAL CHEMISTRY. Dilute Hydrochloric Acid. This acid has the same properties as the strong acid, from which it is made, excepting those depending on greater concentration. It contains 10 per cent of absolute acid, and has a specific gravity of 1.050. Nitrohydrochloric Acid. This acid, sometimes called '^nitromuriatic acid," "chlo- ronitric acid," " chloroazotic acid," ^' aqua regia,'' iitc, is made by mixing 18 parts of nitric acid with 82 parts of hydrochloric acid, in a capacious vessel, and allowing to stand until effervescence ceases. It is then directed to be poured into glass-stoppered bottles, which should not be more than half filled, and kept in a cool place. This acid was called aqua regia by the early chemists because of its property of dissolving gold, the king of the metals {regia from rex, which means king). There are various opinions regarding the nature of the reaction between strong nitric and hydrochloric acids, but the uitrosyl chloride theory seems to be shared by most authorities at present: HNOg + 3HC1 = 2H,0 + NOCl + CI,. The presence of free chlorine gives, very probably, to the acid its power to dis- solve gold and other metals which have little affinity for oxygen. The nitrosyl chloride, ISTOCl, remains entirely in- active and unchanged during the solution of gold. Nitrohydrochloric acid is a golden-yellow, fuming, cor- rosive liquid, having a strong odor of chlorine; it liberates iodine from solutions of iodides. If kept exposed to sun- light it decomposes into hydrochloric acid, principally, and loses its chlorine. The pharmacist should never keep it in large quantity because of its proneness to decomposition PHARMACEUTICAL AI^D MEDICAL CHEMISTRY. 145 and deterioration. Especial care should be observed not to transfer it to bottles before effervescence has entirely ceased, lest the pressure burst the bottles. Uses in Medicine. — Nitro-hydrochloric acid is employed in diseases of the liver, stimulating especially the flow of bile. It is used externally in very dilute solution as bath. The dose of the fresh acid is 3 to 5 drops, largely diluted. Dilute Nitro-hydrochloric Acid. Made as the above, with the addition of water when effer- vescence has entirely ceased ; the dilute nitric and hydro- chloric acids do not react, hence the employment of the strong acids and subsequent dilution with water. It is claimed by good authority that the water in the dilute acid causes a decomposition of the products formed by the reac- tion of nitric and hydrochloric, and a re-formation of the original acids, with a little nitrous acid as well. Clinical experience confirms the claim that dilute nitro- hydrochloric acid is not an eligible preparation. The strong acid is employed preferably, well diluted just before administration. Dilute Hydrobromic Acid. Properties. — Hydrobromic acid is a colorless, clear liquid, of a specific gravity of about 1.077, wholly volatile upon application of heat, odorless and of strongly acid taste and reaction. It contains 10 per cent by weight of absolute acid, corresponding in strength to most of the other dilute acids. There is no stronger acid official, but the market affords several that are more concentrated. Preparation. — The Pharmacopoeia does not give a process 146 PHARMACEUTICAL AN"D MEDICAL CHEMISTRY. for the preparation of this acid, hut there are numerous methods in vogue for its production. The following yields a pure product: Sulphuric acid is made to react on an equal quantity of bromide of potassium in solution, and allowed to stand, to permit the sulphate of potassium, which is formed, to crystallize. The liquid is then poured off into a retort and distilled. The rationale of the process is this: 2KBr + H,SO, = K,SO, + 3HBr, which, it will be seen, is the identical process employed in making hydrochloric acid, excepting that, in making the latter, distillation is resorted to at once. Another method, known as the " precipitation process,^' consists in reacting with tartaric acid upon potassium bromide, and allow- ing the acid tartrate of potassium, or cream of tartar, to crystallize : KBr + H,0,H,0, = KHC,H,0, + HBr. If the mixture is put away for several weeks in a place removed from dust and jarring, nearly all the cream of tartar will crystallize out, leaving the HBr in the liquid. The addition of a little alcohol facilitates the separation of the acid tartrate. This is known as Wade's Buchanan's method. FothergilVs acid is made after Wade's method, but it is somewhat weaker in strength. The acids made by these methods are open to the objection of containing small quantities of cream of tartar in solution. Among the many other methods only one more need be mentioned here, that of GoebeFs Glover's process, which consists in treating barium bromide, BaBr,, with sulphuric I I PHAEMACEUTICAL AND MEDICAL CHEMISTRY. 147 acid, producing HBr and the insoluble barium sulphate as precipitate : BaBr, + H,SO, = BaSO, + 2HBr. The first of these methods, known as Squibb's process, has the advantage over the others of producing a product of greater purity and more definite strength. Tests of Identity. — Solution of silver nitrate produces a yellowish-white precipitate, which is insoluble in nitric acid and very sparingly soluble in ammonia. If chlorine or nitric acid be added to the acid, bromine will be liberated, which is soluble in chloroform or disul- phide of carbon, giving to these liquids a yellow color. The chlorine has a greater affinity than the bromine has for the hydrogen in the HBr, and it therefore removes the bromine to take its place: 2HBr + 01, = 2HC1 + Br,. Nitric acid, when it liberates the bromine, probably does so in this wise : 2HNO3 + 6HBr = 4H,0 + N,0, + 3Br,. Impurities. — Upon keeping for any length of time the acid sometimes becomes yellow; this is due to the libera- tion of bromine. It should not be used unless wholly colorless. Sulphuric acid may be present; if so, it may be detected by BaClj, which gives an insoluble white precipitate. Uses. — Dilute hydrobromic acid is employed medicinally for the same purposes that bromide of potassium and bromide of sodium are used. It is claimed to have advan- tages over the alkali bromides, as potassium and sodium are said to exert a depressing influence upon the system. The dose is up to 2 fluid drams (7.39 cc.) given in syrup or water. 148 PHARMACEUTICAL Ai^D MEDICAL CHEMISTRY. Hydriodic Acid. The third of the halogen acids, hydriodic acid, is official in the form of a syrup of 1 per cent strength by weight. This preparation was introduced in the U. S. P. of 1880, and its introduction grew out of the difficulty of keeping hydriodic acid in aqueous solution, the iodine always be- coming liberated, in a short time rendering the preparation unfit for administration. Experiments have shown that syrup will efficiently preserve the acid. There is about 1.30 gramme acid in 100 cc. syrup. Preparation. — Several methods may be employed in the preparation of syrup of hydriodic acid, and each involves a chemical process. One method is as follows: Ten parts of iodine are dissolved with gentle heat (extreme heat would produce loss of alcohol by evaporation and of iodine by vaporization) in 80 parts of alcohol. When dissolved the solution is added to 150 parts syrup and 150 parts of water, and a current of hydrosulphuric acid gas is passed through the mixture until it acquires a yellowish color and ceases to assume a brown tinge on shaking. The liquid is then fil- tered and evaporated during constant stirring at a temper- ature not exceeding 131° F., until all odor of hydrosul- phuric acid gas has disappeared. When cold it is flavored with spirit of orange 5 parts, and 500 parts of sugar added and enough water to make 1000 parts (all "parts by weight "). It is preserved in small, well-stoppered bottles and kept in a cool and dark place. The chemistry of the process is: I, + H,S = 2HI + S. The H,S may be gen- erated from iron sulphide and sulphuric acid : FeS -|- H^SO, = FeSO, + H,S. The FeS is contained in a flask with a double-perforated cork, through which pass a PHARMACEUTICAL AN"D MEDICAL CHEMISTRY. 149 funnel to the bottom, to convey the acid, and a delivery tube, to carry away the gas. The gas is usually washed by being passed through water before it is conducted into the iodine solution. The sulphur which precipitates dur- ing the process remains behind on the filter. H^S is soluble to a certain extent in water, from which it can be expelled again by heat, hence that direction in the process. Properties. — Syrup of hydriodic acid is a transparent liquid, sometimes colorless, but usually of a pale-straw color, of a specific gravity of 1,313 and containing 1 per cent of absolute acid. If the substances used in its preparation are pure, as they should be, it will contain no impurities, but the U. S. P. gives tests for free iodine, chloride and sulphate. Free iodine will be recognized by the blue color with starch-paste. Chlorides or hydrochloric acid, with silver nitrate give precipitates which are soluble in ammonia. The precipitate with a bromide and silver nitrate is spar- ingly soluble in ammonia. Sulphuric acid is detected by BaCl^. Uses. — This preparation is possessed of the chemical properties peculiar to iodides in general. Its dose is from 15 to 40 minims, considerably diluted. Phosphoric Acids. Preparation. — Phosphoric acid, as the official phos- phoric acid is termed by chemists, is never made by the pharmacist. By the manufacturing chemist it is made by carefully dissolving phosphorus in dilute nitric acid on a water bath. Dilute nitric acid exerts no action upon phos- phorus in the cold, but at an elevated temperature it changes it into phosphorous or phosphoric acid, according to its 150 PHARMACEUTICAL AN"D MEDICAL CHEMISTEY. strength, which must be regulated accordingly. The stronger the nitric acid the more rapidly will it oxidize the phosphorus into phosphoric acid, but with the strong acid the reaction is so violent that the acid is always diluted with water for the operation. Serious accidents have happened from explosions resulting from the use of strong acid. The following equations will serve to demon- strate the reactions of nitric acid with phosphorus : First, when the nitric acid is well diluted : 2P + 2HNO3 + 2H,0 = 2H3PO3 + N,0,; phosphorous acid is produced. This reaction may be resolved thus: The HNO3, when it oxidizes, as has been mentioned, resolves itself into: 2HNO3 = H,0 + 1^,0, + 30; the oxygen attacks the phosphorus, 2P + 30 = P2O3, forming the phosphoroti,9 oxide, which with water produces the phosphorous acid : P,0, + 3H,0 = 2H,P0,. Second, when the nitric acid is less dilute: 6P + IOHNO3 + 4H,0 = 5N,0, + 6H3PO,, forming phosphoric acid. The several steps in this reaction are as in the preceding, excepting that more nitric acid, relatively, is employed, and consequently more oxygen is set free to produce the higher form of oxidation. IOHNO3 = 5H,0 + 5N,0, + 150; the oxygen again at- tacks the phosphorus: 6P + 150 = SP^O^, producing phos- phoric oxide, which with water gives phosphor^c acid. 3P,0, + 9H,0=6H3PO,. The acid last described is official in the U. S. Pharma- copoeia. PHARMACEUTICAL AND MEDICAL CHEMISTRY. 151 Varieties of Phosphoric Acids. — Orthophosphoric anhy- dride, or anhydrous phosphoric acid, P^O^. Metaphosphoric acid, or glacial phosphoric acid, HPO3. Orthophosphoric acid, HgPO^. Diphosphoric acid or pyrophosphoric acid, H^P^O,. Besides these there are, among others of less importance, the following : Anhydrous phosphorous acid, P2O3. Phosphorous acid, H3PO3. Hypophosphorous acid, HgPO^. The PjOg is formed when phosphorus is burned in ex- cess of oxygen, and is in form of a white flocculent powder. With one molecule of water it gives met a-i^hosi^horic acid, and with 3 molecules of water or^/^ophosphoric acid. P.O. P,0, + H,0 + 3H,0 2HP0, .2H,P0 By adding one molecule of water to one of metaphos- phoric acid the orthophosphoric will be formed : HPO3 -f- H^O = H3PO4. This may be made practically by boiling HPO3 with water. If, on the other hand, orthophosphoric acid be heated to drive off one molecule of water, the metaphosphoric will be produced : H3PO, -H,0 HPO, The ortho-acid may be looked upon as a trihydrate, P,0, + 3H,0 (2H3POJ, while the meta-acid is a mono- hydrate P,0, + H,0 (2HPO3). 152 PHARMACEUTICAL AN"D MEDICAL CHEMISTRY. Intermediate between the ortho and meta acids is an- other, the pyrophosphoric acid, H^P^O,. Theoretically this may be looked upon as consisting of one molecule of orthophosphoric and one of metaphosphoric acids : H3PO, + HPO, HPO or, as being derived from two molecules of orthophosphoric acid by the abstraction of one molecule of water : H.P,0, (2H,P0.) -H,0 The meta- is easily distinguished from the orthoacid by its property of coagulating albumen and precipitating with soluble salts of silver and barium, which properties are not possessed by the orthophosphoric acid. The latter gives a precipitate with silver nitrate in an excess of an alkaline solution only, which precipitate is yelloiu, and different from the precipitate formed by jo^/rophosphoric acid under like conditions, which is white. The pyro- phosphoric acid will not coagulate albumen, wherein it also differs from metaphosphoric acid. Meta means beyond, ortho straight, and -pyro fire. The pyro-acid is so termed because it is usually made by heat- ing the orthophosphoric acid. Heated to a much higher temperature, the pyrophosphoric acid is converted into the meta-acid, and the latter, by boiling in water, is recon- verted into the orthophosphoric. According to the foregoing explanation these three acids t PHARMACEUTICAL AND MEDICAL CHEMISTRY. 153 are convertible into each other by the addition or abstrac- tion of water. The salts which these acids produce through the replacement of their hydrogen by metals have the corresponding names: Metaphosphoric acid, HPO3, gives metaphosphates: NaPOg, sodium metaphosphate. Orthophosphoric acid, H3PO4, gives phosphates: NagPO^, sodium phosphate. Pyrophosphoric acid, H^P^O,, gives pyrophosphates: Na^PjO^, sodium pyrophosphate. The Pharmacopoeia recognizes orthophosphoric acid under phosphoric acid and dilute phosphoric, while the pyrophosphoric acid is represented by pyrophosphate of sodium, Na^P^O^, and by pyrophosphate of iron,Fe4(P20,)3. (The latter is insoluble, but the U. S. P. salt is in form of soluble scales, made so by the addition of citrate of sodium.) These acids are all derivatives of the phosphoric oxide, P^Og, and have respectively one, three and four replaceable hydrogen atoms. Varieties of Phosphorous Acids. — The phosphoro?^5 oxide, P^Og, yields, as above stated, phosphorous acid, by the addition of water : + 3H,0 2H,P0, This acid forms phosph^Ye5 with bases. It has only two replaceable hydrogen atoms, and is sometimes written H^HPOg, to show that there are only two replaceable hydrogen atoms. Sodium phosphite would be written Na.HPOg. 154 PHARMACEUTICAL AKD MEDICAL CHEMISTRY. The oxide corresponding to %;oophosphorous acid, H3PO2, is not known ; it would be P^O. Hypophosphoroiis acid has only one replaceable hydrogen atom, and should be written HPH^Oj. It is represented in the Pharmacopoeia by sodium, po- tassium, calcium and iron hypophosphites. Their respective formula are NaPH,0„ KPH,0„ Oa(PH,OJ, and Fe^ (PH,OJ, (The student is advised to become thoroughly ac- quainted with the chemistry of phosphorus and its acids; as set forth in the foregoing chapter. He will find it neces- sary to have frequent recourse to it in his practice and studies.) Properties of Phosphoric Acid. — Phosphoric acid is a clear, colorless, syrupy liquid of strongly acid taste and re- action, containing 85 per cent of absolute acid and 15 per cent water. It is odorless, is miscible with water, and has a specific gravity of 1.710 at 15° 0. Impurities and Tests. — Occasionally small quantities of metaphosphoric acid, phosphates of calcium and mag- nesium, arsenic, sodium, potassium; hydrochloric, nitric, phosphorous and sulphuric acids, and more than 15 per cent of water are found. Phosphate of sodium has at times been detected in large quantities. To detect calcium and magnesium, the acid is super- saturated with ammonia- water; a precipitate indicates presence of the bases. Arsenic, lead and other metals are precipitated by pass- ing sulphuretted hydrogen through the acid for half an hour. A yellow precipitate indicates arsenic. Sodium or potassium may be detected by precipitating with acetate of lead (producing insoluble phosphate of \ PHARMACEUTICAL AND MEDICAL CHEMISTRY. 155' lead and soluble acetate of sodium and potassium), filter- ing and evaporating the solution to dryness. The residue will impart a yellow color to the colorless flame of a Bunsen-burner (sodium), and a purple flame if viewed through blue glass (potassium). Hydrochloric, nitric and sulphuric acids may Be looked for by the tests given before. Phosphorous acid, if present, decolorizes solution of permanganate of potassium. The Physiological Action^ of Phosphoric Acid is that of a powerful stimulant to the brain and nerves. Au- thorities differ as to its medicinal value. There is prob- ably some truth in the assertion of J. A. Thompson, that the complete oxidation of phosphorus impairs, or even de- stroys, its therapeutic properties. Dilute Phosphoric Acid. This contains 10 per cent of orthophosphoric acid, and all that has been said concerning phosphoric acid is ap- plicable to the dilute form. Glacial Phosphoric Acid. This acid is not made directly from phosphorus, but from calcined bones, by digesting them with suphuric acid. The insoluble sulphate of calcium which is produced is removed by filtration, the filtrate neutralized with am- monia, separated from the precipitated phosphates and evaporated to dryness. The residue, composed of phos- phate of ammonium, is then heated until all ammonia is driven off: (NH.),PO, — 3NH. H3PO, 156 PHARMACEUTICAL AKD MEDICAL CHEMISTRY. The orthophosphoric acid, HgPO^, upon continued ap- plication of heat parts with 1 molecule of water to form the dry fused glacial acid, which is the metaphosphoric acid : H3PO, — H„0 HPO, Properties. — Griacial phosphoric acid is in transparent, colorless, glass-like masses, or in the form of sticks, obtained by fusing and pouring into moulds. It deliquesces on exposure to the air, dissolves in water and alcohol; the solutions having a strongly acid taste and reaction. It is never chemically pure, always containing sodium or other bases, which latter, however, are neces- sary to the formation of a solid acid. The chemically pure acid is a soft, gum-like mass. Impurities. — The impurities likely to occur in glacial phosphoric acid are those occurring in phosphoric acid. For the detection of these the same tests may be employed. Arsenous Acid. The substance described in the Pharmacopoeia under this title is not an acid, all acids, as before stated, requiring hydrogen in the base. The term is a conventional one: it ought to be arsenous oxide, which better expresses its chemical composition. This oxide becomes an acid (like SO3, CO,, P2O5, etc.) when combined with water: ASjOg + SH^O = 2H3AsOg, arsenous acid. There is another oxide of arsenic, a higher one, As^Og, which with water produces arsenic acid : AsO, + 3H,0 = 2H3ASO,. PHARMACEUTICAL AN^D MEDICAL CHEMISTRY. 157 Arsenic acid is usually made by oxidizing arsenous oxide with nitric acid: 3As,03 + 7H,0 + 4HNO3 = 6H3ASO, + 2N,0,. Preparation. — The arsenous acid is the only one of im- portance to the pharmacist. It is obtained in nature from arsenical ores by roasting in furnaces and conducting the hot vapors to surfaces on which they may cool and con- dense, usually cast-iron vessels with conical heads. Ar- senic is easily volatilized, taking up oxygen from the air as soon as it enters the gaseous condition, forming As^Og, which condenses into a sublimate. Properties. — It is a heavy crystalline or amorphous pow- der, or crystalline masses, semi-transparent, with streaked appearance. Soluble in from 30 to 80 or 90 parts of water, its solubility varying probably with the nature of its structure. In alcohol it is very little soluble, but hydro- chloric acid facilitates its solution, as do also the alkalies. Arsenous acid is permanent at ordinary temperatures, but when heated it volatilizes unchanged, emitting a garlicky odor, especially when reduced on ignited charcoal. Chem- ically, arsenous acid responds to all the tests for arsenic. The latter will be given in the chapter on Arsenic Salts. Poisonous Properties of Arsenous Acid. — See Arsenic Salts. Antidotes to Arsenous Acid. — There are two antidotes recognized by the U.S. Pharmacopoeia: (1) the freshly pre-, cipitated hydroxide of iron, obtained by adding water of ammonia to solution of tersulphate of iron, pouring pre- cipitate upon muslin strainer, draining and washing with water to remove any excess of ammonia or iron; (2) hydrated oxide of iron with magnesia, prepared by mixing calcined 158 PHARMACEUTICAL AND MEDICAL CHEMISTRY. magnesia with solution of tersulphate of iron. (See chapter on Arsenic Salts for equations.) Until the antidote can be obtained, the poison should be removed as far as possible by inducing vomiting by means of the finger or a feather, or by administering a prompt emetic of mustard, salt and warm water, or 20 grains of powdered ipecac. Demulcent drinks, such as milk, flour and water, or white of egg and water, envelop the poison and retard its solution. Uses of Arsenous Acid. — It is employed usually as an al- terative in doses of -^q- to gV grain. Chromic Acid. This is really an oxide of chromium, and resembles in point of faulty nomenclature the acid previously de- scribed. Crystals of the acid readily separate from a mix- ture of a concentrated solution of potassium bichromate and strong sulphuric acid. The acid should be added to the bichromate solution slowly and with constant stirring, to prevent undue heating. The crystals, after removal of the mother-liquor, are washed with nitric acid, allowed to drain, and preserved in small well-stoppered bottles. This equation illustrates the reaction : K,Cr,0, -h 2H,S0, = 2Cr03 + 2KHS0, -f H,0. The acid sulphate of potassium remains in solution. Properties. — Chromic acid is in form of small crimson needles or columnar crystals, very deliquescent, and hence easily soluble in water. It attacks the skin, producing a caustic effect, wherefore it should always be handled with caution. It is best to use a glass spatula in manipulating it. Owing to the fact that it contains a large proportion PHARMACEUTICAL AN'D MEDICAL CHEMISTRY. 159 of oxygen it readily attacks and oxidizes a good many bodies, causing combustion or explosion. Glycerin, sweet spirit of nitre and strong alcohol are among the easily oxid- izable bodies to which chromic oxide should not be added. Uses. — Chromic acid is never used internally. It is val- uable as an antiseptic and powerful caustic, and is used largely to remove warts and callous growths. 160 PHAEMACEUTICAL AND MEDICAL CHEMISTKY. The Metals. Physical Properties. — There is a wide range in the densi- ties of the metals — lithium^ sodium and potassium being the three which are ligliter than water, while osmium is the heaviest, with iridium, platinum and gold following. The metals have all, more or less, a metallic lustre, their sur- faces admitting of being highly polished. In color they range from the white of silver to the red of copper and yellow of gold. Bismuth is white, but has a faint pinkish hue. Certain of the metals are malleable, a property which permits of their being extended by hammering or rolling. Gold is the most malleable of all the metals. Gold leaf is one of its attenuated forms. Ductility is a property involving the principle of tenacity, or power of resisting tension, possessed by metals which admit of being drawn out into wire. Volatility is probably possessed by all metals, but suffi- ciently high temperatures cannot be obtained to volatilize all. Mercury easily volatilizes at low temperature, but the highest degree of heat that we can to-day obtain only fuses or melts many of the metals. Chemical Properties. — Besides the combinations before referred to, into which metals enter — i.e., with the non- metals, forming oxides and salts — they combine with other metals. The compounds formed by the union of metals among themselves are called alloys, excepting that when one of the metals is mercury, the union is called an amal- gam. It is not positively known whether the metals in alloys combine chemically or not. One of tlie chief char- PHARMACEUTICAL AND MEDICAL CHEMISTRY. 161 acteristics of the chemical force is its property of totally changing the physical appearances and properties of the bodies acted upon. This is not observed in case of alloys : the physical properties are still those of metals, and there is no such obliteration of the identity of the constituents as ensues when a metal combines with, e.g., oxygen or sul- phur, but on the other hand, the evolution of much heat in the formation of some alloys, notably those of potassium and sodium, would indicate that there is chemical action. The alterations of character are usually in hardness, melt- ing-point, color, tenacity and specific gravity. The com- bination, if it is such, takes place when the metals are melted together. While some chemists prefer to look upon alloys as chemical combinations, yet admitting that the chemical force exerted is very feeble, others consider them mere mechanical mixtures or solutions of one metal in the other in the liquid state. Some of the commoner alloys are: Brass, consisting of copper and zinc; Gun-metal, consisting of copper and tin; Bronze, consisting of copper, zinc and tin; German silver, consisting of copper, zinc and nickel; Pewter or Britannia, consisting of copper, tin and antimony; Shot, consisting of lead, with antimony or arsenic; Gold coin, consisting of gold, copper and sometimes silver. Cavities in teeth are usually filled with alloys specially prepared. The process of amalgamation is often resorted to in the extraction of some of the metals. Gold, which principally occurs in the metallic state as gold dust, is obtained from auriferous sand by treatment with mercury. The amalgam formed is heated in a retort, whereby the mercury is re- 162 PHARMACEUTICAL AKD MEDICAL CHEMISTRY. covered by distillation, the gold remaining as a residue in tlie retort. Silver is obtained from its poorer ores Dy tne same method. Unions of the Metals with the Halogens — Haloid Salts. — Chlorides. — Chlorine combines with metals to form chlo- rides. The combinations take place in proportions deter- mined by the atomicity of the metal, and the compounds formed may be looked upon as being derived from as many molecules of hydrochloric acid as the metal has bonds, by the replacement of the equivalent of hydrogen by a metal. This may be more easily comprehended by assuming hydro- chloric acid to be the type of all chlorides. HCl with potassium yields KCl, K replacing H; 2HC1 with calcium yields CaCl^, Ca replacing 2H; 3HC1 with gold yields AuClg, Au replacing 3H; Chlorides may be made in any of the following ways: 1. By acting on metals (antimony, copper, etc.) with element- ary chlorine; or, 2, with hydrochloric acid (zinc, iron, etc.) 3. By acting on oxides (silver) with free chlorine ; or, 4, with hydrochloric acid; and, 5, by dissolving carbon- ates or hydroxides in hydrochloric acid. Oxychlorides and Sulphochlorides are unions of chlorides with oxides and sulphides, respectively. Bismuth oxychloride may be viewed as being the chloride, BiClg, with two of the chlorine atoms replaced by oxygen, BiOCl. Metallic chlorides combine in definite proportions with ammonia and organic bases. Diammonium-platinous chloride, 2NH3.PtCl2, is such a compound, and is used occasionally in testing. Nearly all the chlorides are solu- ble. Notable exceptions are those of silver, lead " and mercurous mercury. PHARMACEUTICAL AND MEDICAL CHEMISTRY. 163 Bromides. — Bromine combines with most of the metals, and produces compounds analogous in composition to the chlorides, which they resemble in most of their properties. Chlorine having stronger affinity for metals than bromine^ replaces the latter in salts, setting it free. Strong sul- phuric acid also liberates bromine from any bromide. Iodides. — Unions of iodine with the metals are called iodides. They are analogous in properties to the chlorides and bromides. Chlorine and strong sulphuric acid will liberate the iodine, which turns blue with starch paste. Cyanides are combinations closely related to the haloid salts, excepting that the radical is composed of two ele- ments, carbon and nitrogen, together called cyanogen and written CN or Cy. Some cyanides are made by heating the metal in cyanogen gas or vaporized hydrocyanic acid. Cyanogen has its source chiefly in nitrogenous organic compounds, and a number of cyanides are made by heating the fixed alkalies with such bodies. A number of the cyanides unite with each other, producing the double cycmides. Ferricyanide and ferrocyanide of potassium are such double salts. K^FeCyg is the union of FeCy^ and 4KCy — ferrocyanide potassium. These double cyanides are important in analysis. Oxygen Salts. — With oxygen the haloid salts produce a different class of salts, better known as belonging- to the oxygen salts; the haloid salts, it should be noticed, contain no oxygen. The oxygen salts may be derived from the corresponding acid by replacing the hydrogen with a metal — potassium in this case: (Potassium chloride, KCl, from HCl, hydrochloric acid.) Potassium chlorite, KCIO^, from HCIO^, chlorous acid. Potassium chlorate, KClOg, from HCIO3, chloric acid, 164 PHARMACEUTICAL AND MEDICAL CHEMISTRY. Iodine and bromine have corresponding salts, also obtained by replacing the hydrogen in corresponding acids. The names of the salts end as above. In a previous chapter it was explained that oxides are conveniently divided into three classes, — viz., acid, neutral and basic, — and that the first and third are capable of unit- ing to form salts, but that in the majority of cases, ^netallic salts are obtained from acids by replacing their hydrogen by a metal, basic or neutral oxide or hydro oxide. It was also explained that acids are unions of acid oxides with water, the oxide of hydrogen, and hence are intermediate compounds between oxides and oxygen salts. Another method of making salts is the interchange of the bases contained in soluble salts; sodium carbonate and barium nitrate will produce the insoluble carbonate of barium, which is precipitated, and soluble sodium nitrate, which remains in solution : Ba(N03), + Na,003 = BaC03 + 2NaN03. Insoluble salts containing halogen elements may also be made by this interchange method : HgCl, + 2KI = Hgl, + 2KC1. The mercuric chloride is decomposed, with the formation of insoluble mercuric iodide and soluble potassium chloride. All haloid salts and acids may therefore be looked upon as constructed after one type, hydrochloric acid being usually taken for the type, H — CI. By replacing the chlorine with any of the other halogen elements the remaining halogen acids may be obtained, and by replacing the hydrogen in these all the various haloid salts are produced. The hy- drogen of the acid or the metal in the salt is the base and the halogen element the radical. Now, oxygen salts may PHARMACEUTICAL AN"D MEDICAL CHEMISTRY. 165 be regarded, as above stated, as compounds of acid oxides with basic oxides, or as analogous in composition to hydro- chloric acid; that is, as being constructed after the hydro- chloric acid type, containing a base and a radical, without reference to oxides. Thus the oxygen salts, sodium nitrate, NaNOg, and calcium carbonate, OaCOg, may be looked upon as constructed from HCl, the Na and Ca taking the place of hydrogen, and the g7'0ups of elements NO3 and OO3 the place of the chlorine. The NO3 and CO3 together as one radical discharge functions similar to those of chlo- rine, and like that element are capable of migrating un- changed and together from one compound to another. It is a subject of discussion among chemists which of these views is the correct one. The former is a rational view and the latter a more convenient one. The latter is also known as the binary theory of salts. Chemists agree that it is impossible to construct formulas capable of representing the exact arrangement of atoms in molecules; it is sufficient to be able to exhibit the combin- ing power of the atoms of the several elements in compounds and the manner in which any group of atoms splits up into smaller subordinate groups under the influence of other compounds. To illustrate this sulphuric acid is a good example, as it splits up or decomposes in four ways, accord- ing to the reagent used: 1. With zinc it splits up into H^ and SO4, the H^ becoming liberated and the SO^ combining with zinc to form its sulphate: Zn -f H^SO^ = ZnSO^ + H^. 2. If lime, CaO, is added to sulphuric acid, it decomposes the latter into H2O and SO3, the H^O becoming free and the SO3 uniting with the OaO to form calcium sulphate: CaO + H,SO, = H,0 + CaSO,. 3. Sulphuretted hydrogen is formed when sulphide of iron, FeS, is added to sulphuric 166 PHARMACEUTICAL AKD MEDICAL CHEMISTRY. acid; H^SO^ in this case decomposes into H^S and 0^. H^SO, + FeS = H,S + FeSO,. 4. With barium dioxide, BaO^, sulphuric acid splits up into H^O^ and SO^; H^SO^ + BaO, = H,0, + BaSO,. Normal, Acid and Double Salts. — Monobasic acids pro- duce oiormal salts, by the replacement of their hydrogen by a metal. The metal may take the place of the hydrogen in one, two or three molecules of hydrochloric acid, for instance: HCl + K =.KC1 + H; 2HC1 + Zn = ZnCl, + 2H; 3HC1 + As =. ASCI3 + 3H. A normal salt is therefore one derived from an acid by replacing all the hydrogen in it by a metal: OaCOg, BaSO^. Acids which are hihasic or dibasic — that is, which have two replaceable hydrogen atoms — may produce two kinds of salts, normal and acid salts. The normal, as in case of salts derived from monobasic acids, have an equivalent of the metal in place of all the hydrogen, while the acid salt still contains some hydrogen, only part of it having been replaced in the acid by a metal: H^SO, + Na =: NaHSO,, acid sulphate of sodium, + H; H2SO4 -\- Na^ = Na^SO^, normal sulphate of sodium, + H^. An acid salt, therefore, is a salt containing a metal and hydrogen in its base (NaH)(003), (KH)(C,H,OJ. If the hydrogen in a dibasic or tribasic acid be replaced loy two metals a double salt results: Eochelle salt, double tartrate of sodium and potassium, KNaO^H^Og, is derived from tartaric acid, H^C^H^Og, by replacing one of its hy- drogen atoms with potassium, the other with sodium. Bibasic acids may therefore produce normal or neutral PHARMACEtJTICAL AKD MEDICAL CHEMISTRY. 167 salts, as they are sometimes called, acid or Msalls, and double salts. Tribasic acids may produce as many kinds of salts as the bi basic, and in addition tertiary salts, having three metals in the base. Basic Salts or Oxysalts. — Normal salts give rise to two other classes of salts, the basic salts or oxysalts, and anhydro salts. The composition of these will be better understood by looking upon salts again as compounds of acid oxides with basic oxides, as stated above. (The terms basic oxide and basic salt should not be confounded by the student.) Normal sodium sulphate, ISTa^SO^, equals Na^O and SO3; Normal bismuth carbonate, 613(003)3, equals Bi^Og and 300,; Normal ferric sulphate, Fe2(S0j3, equals Fe^Og and SSOg. In these it will be seen that there are as many acid oxide molecules as there are oxygen atoms in the basic oxide. When the proportion of the acid oxide is less, the salt is termed a basic salt : Basic bismuth carbonate, Bifi{QO^^, is Bi^Og and 200^; Basic bismuth carbonate, Bi^O^OOg, is Bi203 and 00^; Basic ferric sulphate, Fe^O^SO^, is Fe203 and SO3; Basic ferric sulphate, Fe20(SOj2^ is Fe203 and 2SO3. It will be noticed that the acid oxides are less in number than the number of atoms of oxygen in the basic oxide. There is an analogy of these basic oxysalts with the oxy- chlorides, oxybromides, etc.: thus the basic bismuth chlo- ride has the formula BiOOl or Bi^O^Ol^, the group of ele- ments CO3 in the basic carbonate acting as the single ele- ment does in the basic chloride. Some normal salts absorb moisture from the air; the moisture being water, H^O, there 168 PHARMACEUTICAL AND MEDICAL CHEMISTRY. is consequently a greater proportion of base present than of acid, and a basic salt results: dFeSO^ + 0^ — Fe2(SOj3, normal ferric sulphate, and Fe^O^SO^, basic ferric sulphate. The FeSO^ is a ferrous salt and by the absorption of oxygen becomes oxidized to the ferric salt. The second class of salts of the normal kind are those which contain an excess, not of the basic oxide, as in the above, but of the acid oxide. Thus: Sodium anhydrosulphate, Na^S^O,, is Na^O and 2SO3; Potassium anhydrochromate, K^Or^O,, is K^O and 20r03. There are two acid oxides to one basic oxide in each of these salts. They are sometimes called acid salts because of the excess of acid oxide, and sometimes hi salts for the same reason, and because in the above cases they have two mole- cules of the acid oxides to designate. The prefix anhydro should designate, when added to the name of a normal salt, an addition to the latter of a molecule of the anhydrous acid. By anhydrous acid is meant that which is left after all the hydrogen and enough oxygen to form water have been re- moved from an acid; the anhydride of sulphuric acid is SO3: H,SO, = H,0 + SO3. SO3 added to Na.SO, gives Na,S0,S03, or Na,S,0,. So Cr03, added to K,CrO„ gives the so-called bichromate of potassium, K^Cr^O^. Kinds of Formulas. — Formulas are usually collections of symbols employed to express the compositio7i of compounds. The simplest is the empirical formula, which expresses merely the proportiofis of elements in compounds. Ben- zene, CgHg, contains six molecules of hydrogen and as many of carbon; hence its empirical formula is CH. A Molecular Formula expresses, in addition to this numerical relation, the actual number of atoms in a mole- PHARMACEUTICAL AND MEDICAL CHEMISTRY. 169 cule. CgHg is the molecular formula of benzene, NaCl for common salt, chloride of sodium, etc. A Ratioi^al Formula shows at a glance the disposition of the compound toward reagents or other compounds hav- ing chemical afl&nity. The rational formula for sulphuric acid is H^SO^, which is to show that the H^ or the SO^ may be replaced; of hypophosphorous acid H(PH302), meaning that only one hydrogen atom may be replaced, and that the (PH^OJ together form a group which behaves chemically as a single element would. H3PO2 would not be a rational formula for hypophosphorous acid. A Graphic Formula indicates the equivalent or com- bining values of atoms, and the manner in which these are satisfied by combination. This is done by arranging the symbols in diagrams in such a way that each atom is con- nected with others by a number of lines or bonds cor- responding to its atomicity or degree of equivalence, a monad having one bond; a diad, two; a triad, three, etc. For example : Sulphurous acid, H^SOg. Sulphuric acid, H^SO^ Here the S has four bonds, In this the S has six H one and two. bonds. Calcium carbonate, Calcium phosphate, CaCOg. Oa3(POJ,. Ca<^\p_^ Ca<; ^C = Ca<5 Ca< 0-7P = ■0/ Ca has two, carbon four Ca has two, two, and oxygen two bonds. and P five bonds. 170 PHARMACEUTICAL AKD MEDICAL CHEMISTRY. Graphic formulae are also called structural or constitu- tional. They do not represent the actual arrangement of the atoms in the molecule; chemists are ignorant of how atoms are arranged, and if they knew they could not rep- resent the arrangement on a plane surface. It will be seen from the above diagrams that each atom has its bonds satis- fied by union with a bond belonging to some other atom. The radical of a salt or acid is often spoken of as an unsat- urated group of elements. The SO^ is the sulphuric radical and has two free bonds, whose places in sulphuric acid are occupied by hydrogen : The two free bonds may be saturated with two atoms of a monad metal, or with one atom of diad metal. The (SO J acts as an element with two bonds would. In the same way the nitric radical (NO3) performs all the functions of a single atom with one bond: ^0 In writing graphic formulas for salt containing oxygen, the water type is usually employed. H^O = H — — H, the left hydrogen in case of salts being replaced by metals, and the right by a single element or a group of elements. The number of bonds which the base has determines the num- ber of molecules of water to be taken. Sulphuric acid has two bonds in the base, H^, hence the graphic formula must be constructed after two molecules of water: ► PHAEMACEUTICAL AND MEDICAL CHEMISTRY. 171 H— 0— H H— 0— Q^O H— 0— H H— 0—10=0 It will be seen that the two right-hand hydrogen atoms are replaced by SO^. Written after the hydrochloric-acid type, water is derived from HCl by replacing the CI with OH, and, vice versa, the HOI from H,0 by replacing the OH with 01. The student is urged to read again the opening lessons under the Mineral Acids, to which the above is supple- mental. 172 PHARMACEUTICAL AND MEDICAL CHEMISTRY. The Alkalies. IisT the beginning of the course the student learned that the elements are divided, for convenience of study, into divisions and subdivisions, and that the two primary divi- sions represent metals and non-metals respectively. All of the important non-metals have now been studied indi- vidually and in their important combinations with each other. The acids, the last subject of study, may be looked upon as belonging to the latter — i.e., to combina- tions containing only non-metals, if hydrogen is con- sidered a non-metal, which is disputed by some on the seemingly valid ground that in its chemical behavior it resembles the metals more closely than the non-metals. The student will now go furthur and confine his attention to the metals and their combinations with the non-metals, which combinations are termed salts. Salts are usually unions of metals with some combination of non-metals, the combination usually, 7iot always, being an acid. An acid may be viewed, therefore, in the additional sense of being a prepared condition of one or more non-metals for combining with a metal or metals. (See introductory chapter to the study of the Inorganic Acids.) The first convenient subdivision of the metals is the alkalies, or alkali metals — sodium, potassium, lithium, caesium and rubidium. The latter two are of no importance to the pharmacist. The hypothetical ammonium is usually included in this division. They are called alkalies because they were formerly, and still are, to an extent, obtained from the ashes of a plant called glassivort (which ashes yielded not only soda PHARMACEUTICAL AND MEDICAL CHEMISTRY. 173 and potassa, but which were also employed in the manufac- ture of glass). The name of the ashes in Arabic is gali; in French and Spanish, call. The Arabic prefix al is equiv- alent to our English article the. The Arabic word galaj signifies " to roast in a pan/^ and originated probably from the manner in which the ashes were collected. Soda and potassa were obtained by a process of lixiviation — i.e., by treating the ashes with water, which dissolved out both sub- stances and yielded them up again upon evaporation. This was the original method of obtaining soda and potassa. Properties. — The alkali metals resemble each other in many of their physical properties. There is one dissimi- larity, however, that is marked. Sodium, potassium and lithium and their salts are fixed, whereas ammonium and its salts are volatile. This distinction is brought to mind by the terms " fixed alkalies " for the former and " volatile alkali " for the latter. Fixed means remaining permanent upon the application of heat, and volatile, dissipating or entering the gaseous state in contact with heat. In com- position there is also a difference between the fixed alkalies and the volatile alkali; each of the former consist of a single element, K, ISTa, and Li, while the latter is compound, consisting of the two elements hydrogen and nitrogen, NH^, but the NH^ is purely hypothetical, and used for con- venience — NH3 is the base. This may not be a distinction; that which is termed ammonium we have succeeded in decomposing into the two elements hydrogen and nitrogen, while sodium, potassium and lithium have resisted up to the present all attempts at further subdivision, and hence are called elements. The bodies which we now call elements may be com- pounds whose constituents have more chemism or chemi- 174 PHARMACEUTICAL AND MEDICAL CHEMISTRY. cal affinity for each other than for other bodies. It may be that there are bodies which, if our elements or some of them are compounds, have greater affinity for one or the other of the constituents, but if there are, they have never been brought in contact or condition to exert their greater power of chemical affinity. Whenever the latter happens a new element or elements will be discovered. The annals of chemical history verify this^ as now and then a body which had been supposed to be simple is found to be com- pound. The alkaline hydroxides resemble each other in the fol- lowing common properties: .They (1) turn red litmus- paper blue, and (2) colorless phenol-phthalein solution to a fuchsine red, (3) neutralize acids, (4) form salts with acids, which are neutral or acid according to the propor- tion of the acid, and sometimes alkaline; (5) saponify fats — that is, form soap with fatty bodies, and (6) cauterize the skin. The metals of the alkalies are all soft (easily cut with a knife), all lighter than water, fuse very readily at low temperatures and volatilize* at high temperatures, decompose water with the evolution of hydrogen, combine with great energy with oxygen, forming strongly basic oxides, which dissolve easily in water, producing alkaline hydroxides, which are powerfully caustic : K, or Na, -f 2H,0 = 2K0H or 2NaOH + H,. Sodium Hydroxide. 2K, + 0, = 2K,0. K,0 + H,0 = 2K0H. Potassium oxide. (Basic.) They all form alums and produce basic oxides with oxygen — that is, they will unite with acids to make salts in which they will act as hase. Acid oxides, such as SO,, PHARMACEUTICAL AND MEDICAL CHEMISTRY. 175 P^Oj, OO2, etc., constitute the acid portion of a salt; thus, sulphite of sodium, Na^SO,, is composed of: The base K^O, and The radical or acid. SO2 Making the salt K^SOg Attention is again directed to the synonomy of the terms base and basylous radical, and radical and acidulous radical. In the above salt the K^O may be termed sim- ply the base or the basylous radical, and the SO^ the radical or the acidulous radical. The latter form of nomenclature assumes that a salt is composed of two radicals or roots, one a base and the other an acid. The former mode is preferable for its brevity — i.e., base and radical. The metals of the alkalies form only one chloride each, their salts are all colorless and soluble; and all but ammonium give characteristic colors to colorless flames. Sodium colors the Bunsen-burner flame intensely yellow, potassium gives it a distinct purple hue if viewed through blue glass, and lithium produces a bright crimson color. Caesium means blue, and rubidium, red. Alums. It is a peculiar fact that all the metals of the alkalies form alums, double salts of great interest. An alum may be defined to be a double salt formed by the union of the sulphate of an alkali metal with the sulphate of a pseudo-triad, and having 24 molecules of water of crystallization. For illustration: Potassa-alum has the formula K^Al^- (SOJ424H2O, which shows that theoretically it is com- posed of : 176 PHARMACEUTICAL AND MEDICAL CHEMISTRY. Potassium sulphate KjSO^ Aluminum sulphate (pseudo-triad) K2A12(S0J3 K,A1,(S0,). In crystallizing it takes up 24 molecules of water. The following alums may be resolved as the potassa alum: Iron alum, K2re2(S0j424H20, containing potassium. Iron alum, (NHj2Fe2(SO^)424H20, containing ammo- nium. Chrome alum, {NHJ,Cr,(S0J,2.'^{VO^^, is formed, which is re- moved by filtration. The solution is evaporated and the salt granulated or allowed to crystallize. In evaporating ex- treme care should be taken not to permit the temperature to rise above 180° F. for fear of explosion. The salt should never be kept in warm places, as it is very liable to explode and disengage the powerfully-poisonous PH3. This is a salt which the pharmacist is wise to buy from a reliable house. It enters into the Syrup of HypopJiospMtes, and is usually employed to make the other hypophosphites of the IT. S. P. and of the market. Precipitated Calcium Phosphate. Calcii Phosphas PrcBcipitatus. Ca3(P0j2- — Calcined bones are dissolved in hydrochloric acid and the solution precipitated with ammonia-water, the precipitate thoroughly washed or strained and dried. Bones contain the phosphate of calcium, and in order to obtain this in a finely-divided state it is caused to enter solution, from which it is precipitated as a fine powder. It is a permanent powder, insoluble, and used for distributing the oils in making the aromatic waters. It is better adapted for this purpose than magnesium carbonate, because of its greater insolubility. Its principal use was in preparing the PHARMACEUTICAL AND MEDICAL CHEMISTRY. 213 8yrup of Lactophosphate of Calcium, U. S. P. 1880, which was made by dissolving the freshly-prepared phosphate in lactic acid and mailing into syrup with sugar and flavoring with orange-flower water. The 1890 U. S. P. directs the precipitated carbonate in place of the phosphate in making the syrup of lactophosphate of calcium. Strontium Salts. The strontium salts have lately been introduced into therapeutics, and they seem designed to occupy a very prominent place in the modern materia medica. Their use in medicine was so long deferred because of the belief that they were poisonous. The Prench physiologist. Dr. La- borde, however, lately proved that the toxic properties of salts of strontium were due to the presence of the poison- ous barium, and that when the latter is removed the pure strontium salts are therapeutic agents of such value as to likely replace, it is predicted by some, the alkali and alkaline-earth salts in medicine. The first to prepare chemically pure strontium salts was the French chemist Paraf-Javal. All the natural compounds of strontium: strontianite, a carbonate; celestine, a sulphate, and others, contain barium, which is removed with difficulty in the process of purification. Every pharmacist should there- fore examine his strontium salts for barium. This is easily accomplished by adding a few drops of dichromate of potassium test-solution (a ten per cent solution) to a solution of one part salt in 20 of distilled water — a tur- bidity would indicate the presence of barium and the need to reject the salt. Properties and Tests for Identity and Purity.— The 214 PHARMACEUTICAL AND MEDICAL CHEMISTRY. Pharmacopoeia recognizes three strontium salts, the bro- mide, the iodide and the lactate. They are all hydrous, the lactate containing three molecules of water and the bromide and iodide six each. The application of heat at first melts the salts, then fuses them causing the loss of their water of crystallization; a higher heat decomposes them. They impart an intense red color to a non-luminous flame. They are easily soluble in water; the lactate is permanent in the air, while the bromide and iodide are very deli- quescent and prone to decomposition, for which reason they should be kept in well-stoppered bottles. Each of the salts in solution is precipitated as sulphate with the solution of any soluble sulphate. Calcium sul- phate is very sparingly soluble in water, but yet its solu- tion will precipitate strontium, showing that the strontium sulphate is less soluble than the calcium sulphate. Potassium chromate solution forms a yellow precipitate of strontium chromate in solutions of strontium salts. Soluble carbonates also precipitate soluble strontium salts. A l-in-20 aqueous solution should not be affected by hy- drogen sulphide, either before or after acidulation with a drop of hydrochloric acid — this would indicate the absence of arsenic, lead, copper. Ammonium sulphide test-solu- tion (H^S passed into ammonia-water to saturation) should not alter the aqueous solution, which would indicate the absence of iron, aluminum and other metals. Strontium Bromide. strontH Bromidum. SrBr^ + GH^O. — This salt may be obtained by treating hydrobromic acid with strontium carbonate, filtering, evaporating and crys- tallizing : SrC03 + 2HBr = SrBr, + H,0 + CO,. The carbonate should be pure. The bromide also results if strontium is burned in bromine vapor. The salt is odor- \ PHAEMACEUTICAL Ai^D MEDICAL CHEMISTRY. 215 less, has a bitter alkaline taste, and occurs in forms of colorless, transparent, six-sided crystals. Properties are given above. Medicinally the bromide is recommended as a substitute for the bromides of other bases in the treatment of epilepsy and allied conditions. Strontium Iodide. Strontii lodidum. Srl^ + 6H„0. — If a solution of hydriodic acid is saturated with strontium hy- droxide, the strontium iodide results, which may then be obtained by evaporation: 2HI + Sr(OH), = Sri, + 2H,0. The iodide is in transparant, colorless plates, odorless, bitterish taste, deliquescent. It turns yellow if exposed to air and light, due to the liberation of iodine, and hence should be kept well preserved in small dark, amber-colored glass-stoppered bottles. See properties above. Medicinally the iodide is claimed to have the alterative action of iodides, but without depressing the general nutri- tion, or irritating the intestinal canal. Strontium Lactate. Strontii Lactas. Sr(03H,03)2 + SH^O. — Strictly pure strontium carbonate is dissolved by means of gentle heat in absolute lactic acid diluted with water : SrOO, + 2HC,H.O, = SrCC.H.O,), + H.O + CO,. The salt is obtained from the solution by evaporating and granu- lating. The salt occurs in form of a white granular powder or crystalline nodules, odorless, permanent in the air. For other properties and tests see above. The lactate is claimed to be a successful remedy in the treatment of nephritis and chronic albuminuria. Dose, 0.65 to 1.95 Gm. 216 PHARMACEUTICAL AN"D MEDICAL CHEMISTRY. Barium. The salts of this metal are not of sufficient interest to the pharmacist to merit more than mention. The chloride of barium is a very useful reagent in solution for sulphates, the sulphate of barium being wholly insoluble: BaCl^ -f Na^SO, = BaSO, + 2NaCl. The dioxide, BaO^, is employed in the preparation of per- oxide of hydrogen, and the nitrate and hydroxide dissolved in water are used as test solutions. Magnesium Salts. Magnesium occurs in a great variety of combinations and is widely distributed throughout nature, but pharmacy derives its supply at present chiefly from the silicious hy- drate found in the serpentine rocks of New Jersey, Penn- sylvania and Ohio. The principal source formerly was the sulphate obtained from the Epsom Springs, in England. The word ^'^ magnesia ^Ms derived from the nauie of a town in Asia Minor in the neighborhood of which two minerals were found in abundance, one of a white color named magnesia alba, and the other of a blackish color termed magnesia nigra. The former was that which we now know as magnesium carbonate, while the latter is the manganese dioxide, called manganese to distinguish it from magnesium. Tests for Magnesium Salts. — Sodium phosphate solution produces, in presence of ammonia-water, a white crystalline precipitate of NH^MgPO^, ammonio-magnesium phosphate. The caustic alkalies produce white gelatinous magma- like precipitates. The presence of ammonium chloride prevents the formation of these precipitates. PHARMACEUTICAL ANB MEDICAL CHEMISTKY. 217 Any soluble carbonate gives with soluble magnesium salts a copious white precipitate. Magnesium Sulphate. MagnesH Sulphas. M-g^O^.l^fi. — The sulphate is made from the mineral serpentine by di- gesting the latter with sulphuric acid, dissolving out the sulphate produced and crystallizing. Some years ago it was almost exclusively obtained by evaporating the water from Epsom Spring, in England, which contained a large proportion of the salt in solution. All other salts are made from the sulphate. It is in small colorless prisms, or acicular needles, efflorescent in dry air, very soluble in water, insoluble in alcohol. The impurities likely to be present, and consequently likely to be present in all of the salts made from it, are chlorides, metals, alkaline earths and alkalies; the U. S. P. permits the presence of 1 per cent of the sulphates of the alkalies. Epsom salt is purga- tive in 1 or 2-ounce doses. Oxalic acid is sometimes mis- taken for it, although there is a great dissimilarity between the crystals. Magnesium Carbonate. MagnesH Carbonas. (Approximately Mg003)4.Mg(OH)2.5H20. — The composition of magnesium carbonate varies somewhat. It always contains hydroxides, and the salt recognized by the IT. S. P. probably contains one molecule of the hydroxide and four of the carbonate, as the formula indicates. There are two carbonates, a light and a heavy one, both made by the same process, the differ- ence being merely in the employment of dilute or concen- trated solutions of sodium carbonate and magnesium sul- phate: 5MgS0, + 5Na,C03 + H,0 = (MgC03),.Mg(0H), + SNa^SO^ -\- CO^. The carbonate precipitates and, when thoroughly washed on a muslin or calico strainer, is dried. Concentrated solutions produce the heavy carbonate. 218 PHARMACEUTICAL AKD MEDICAL CHEMISTRY. which is that recognized by the Pharmacopoeia, and which occurs as a light white powder or in friable blocks or masses, insoluble, odorless, tasteless. It is employed in making the heavy magnesia, solution of magnesium citrate, mixture of magnesia and asafa3tida of the 1880 U. S. P., etc. It is sometimes employed to diffuse the oils in making the medicated waters. Medicinally it is an antacid. Magnesia. Magnesia. MgO. — This is the light magnesia or calcined magnesia, made from liglit carbonate by ex- pelling the CO,: MgC03 + heat = MgO + 00,. I* is a very light, white, insoluble powder, very bulky, odorless, earthy taste, and alkaline when moistened with water. Magnesia is laxative, and is usually combined with powdered rhubarb. Heavy Magnesia. Magnesia Ponderosa. MgO. — This corres- ponds in composition and all properties to the above, differing from it only in being heavier. It is made by ex- pelling the CO, from the heavy carbonate. Solution of Magnesium Citrate. Liquor Magnesii Citratis. — This very popular refrigerant laxative is a freshly prepared solution of magnesium citrate flavored with lemon and sugar, and made refrigerant and sparkling by confining the CO, disengaged from potassium bicarbonate: SMgCOg -f- 2H.C.H.0, = Mg,(C.H.O,)., + 3H,0 + 3C0,. Sometimes the calcined magnesia is employed in place of the carbonate; the disengagement of the CO, is thereby obviated. The solution is kept in strong 12-ounce bottles, with the cork tied tightly over the neck of the bottle to prevent its being forced out by the CO, from the potassium bicarbonate. The latter coming in contact with the citric acid, which is always in excess, loses its CO, by double composition accord- PHARMACEUTICAL Ai^D MEDICAL CHEMISTRY. 219 ing to this reaction: 3KHCO3 + H30,H,0, = K30,H,0, (potassium citrate) -|- SH^O -J- SOO^. Effervescent Magnesium Citrate. Magnesii Citras Efferves- cens. — This effervescent salt is made by mixing intimately magnesium carbonate, sodium bicarbonate, powdered citric acid and sugar, and rubbing to a paste with alcohol. This paste is then passed through a coarse sieve and dried. When brought into contact with water, solution of the acid and bicarbonate takes place, and they react upon each other and upon the carbonate and produce effervescence through the liberation of CO,. It is essential to keep this prepara- tion in well-closed bottles. Magnesium Sulphite. MgS036H20. — Prepared by passing pure sulphurous acid gas into magnesia suspended in water : MgO + SO^ = MgSOg. The sulphite is less soluble than the sulphate. It is employed very much as the sodium and potassium sulphites are. It is a white crys- talline powder which oxidizes by exposure to air. It is no longer official. Zinc Salts. The metal zinc is official in form of irregular granulated pieces or in thin sheets, or moulded into thin pencils, or in a state of fine powder. It is obtained from calamine, the chief source of the zinc salts, by roasting with charcoal and collecting the zinc vapors in water. It is a dyad metal with an atomic weight of 65, combining with numerous acids to form salts. The principal use to which the metal is put is to form the sulphate, from which most of the other salts are made. It is also employed in considerable quantity for the preparation of hydrogen from sulphuric acid: HjSO^ -\- Zn = ZnSO^ -\- H^. The metal is often contami- 220 PHAEMACEUTICAL AND MEDICAL CHEMISTEY. nated with arsenic and in delicate analytical work it is necessary to ^orovide for its freedom from this contamina- tion. The official zinc salts are colorless. Analytical Ee actions. — The alkaline hydroxides give white precipitates in neutral solutions of zinc salts, which precipitates are soluble in excess of the hydroxides. Soluble carbonates produce white precipitates of zinc carbonate in solutions of zinc salts. Sulphuretted hydrogen in alkaline solution or ammonium sulphide yields white precipitate of zinc sulphide. Zinc Sulphate. Zinci Sulphas. ZnSO^.TH^O. — White vitriol, as this salt is often termed, is the product of the reaction of dilute sulphuric acid upon zinc, as shown above. The solution is evaporated and allowed to crystallize, and is puri- fied by recrystallization. The salt is in colorless prisms or acicular needles, efflorescent in dry air, odorless, nauseous taste, and very soluble in water. The impurities likely to be present in this and the salts made from it are chloride, iron, copper, lead, alkaline earths and alkalies. Medicinally it is used externally as an astringent anti- septic, and internally as a very prompt emetic, in doses of from 0.50 to 2.00 Gms. In large doses it is poisonous, and care should be exercised not to mistake it for other harm- less salts, such as epsom salts, etc. Zinc Bromide. Zinci Bromidum. ZnBr^. — Potassium brom- ide in solution with zinc sulphate produces double decom- position, yielding zinc bromide and potassium sulphate, which both remain in solution, and from which the sulphate is precipitated by the addition of alcohol. The remaining solution of the bromide is evaporated to dryness or the salt PHARMACEUTICAL Al^D MEDICAL CHEMISTRY. 221 is granulated. Among a number of methods that just described is regarded as the best. The salt thus obtained is very deliquescent, odorless, of sharp taste, very soluble, and may contain all of the im- purities mentioned under sulphate. The medicinal value of the salt is due to the bromine present. It is occasionally prescribed for the relief of insomnia. Zinc Valerianate. Zinci Valerianas. 7iYi{G^B.fi^)^2llfi. — The zinc sulphate is precipitated by sodium valerianate, and zinc valerianate rises to the surface in the solution, contrary to the usual phenomenon that precipitates deposit: 2Na- C,H,0,+ ZnSO,= Zn(0,H,0,),+ N"a,SO,. The salt occurs in white pearly scales, is permanent, slightly soluble in water, and has a faint odor of valerianic acid. It is a form for the administration of valerianic acid and possesses the same medicinal properties, being used as an antispasmodic and nerve tonic in doses of 0.03 to 0.18 Gm. Precipitated Zinc Carbonate. Zinci Carbonas Prcecipitatus. (ZnC03)23Zn(OII)2. — Zinc sulphate is precipitated by sodium carbonate and the resulting insoluble carbonate thoroughly washed with hot water : SZnSO^ -|- SNa^OOg + 3H3O = (Zn003),3Zn(OH), + 5Na,S0, + 300,. The for- mula will show that the " carbonate," so called, is really a mixture of carbonate and hydroxide. It is an impalpable powder, insoluble except in acids, odorless and tasteless. This carbonate is much finer and purer than the native carbonate, calamine, could conveniently be made. Its prin- cipal use is for external application, either as powder or in form of ointment. Zinc Oxide. Zinci Oxidum. ZnO. — The carbonate, made as above, when calcined, loses its 00,, becoming ZnO — e.g., ZnCOg + heat = 00^ + ZnO. Much of the commercial 222 PHAEMACEUTICAL AI^D MEDICAL CHEMISTEY. oxide is made from calamine^ but for medicinal purposes only the very finest, made from the precipitated carbonate, should be employed. The oxide is a soft, whitish powder, permanent in the air, insoluble and without odor or taste. Zinc Oxide Ointment. — An ointment made by incorpo- rating 20 per cent of the finest quality of zinc oxide with benzoinated lard. Zinc Acetate. Zinci Acetas. Zn{CJtLfi^)^.2B.fi.—Bsisily prepared by adding excess of zinc carbonate to acetic acid, filtering and evaporating the solution or setting it aside to crystallize. (ZnC03),3Zn(OH), + 10HO,H3O, = 5Zn(C,H30J, + 2C0, + 8H,0. Zinc acetate is in soft, pearly scales or tablets, efflorescent in dry air; it is soluble in alcohol and water, has a faint odor of acetic acid, and sharp, metallic taste. Zinc Iodide. Zinci lodidum. Znl. — Zinc and iodine are al- lowed to remain in contact in water until solution takes place: Zn -[- I^ = Znl^. The solution is evaporated and the salt obtained in granular form usually. It is a white, gran- ular powder, very deliquescent, without odor. Its use in similar to that of potassium iodide. Solution of Zinc Chloride. Liquor Zinci Chloridi. ZnOl,. — Zinc is dissolved in hydrochloric acid; the solution, to which some nitric acid has been added to oxidize any iron present, is then evaporated to dryness and the residue dis- solved in water. The second solution is clarified by shaking with zinc carbonate, which precipitates any iron that may be still present, as a carbonate: Zn -f 2HC1 = ZnCl^-f Ha- lf iron is present it becomes FeCl,, thus: Fe + 2H01 == FeOl^ -{- Hj. The FeCl^, ferrous chloride, is oxidized to the ferric chloride with the nitric acid and more HCl, thus: 6Fe01, + 6HC1 + 2HNO3 = 3Fe,Cl, + 4H,0 + N,0,. I PHARMACEUTICAL AND MEDICAL CHEMISTRY. 223 The Fe^Cl, when heated probably decomposes into the insoluble ferric oxide and HCl, the latter volatilizing : Fe^Ol, + heat + 3H,0 = Fe,03 + 6HC1. Any Fe^Cl, re- maining unoxidized is removed by the addition of the zinc carbonate, which produces the insoluble ferric hydroxide and carbonate : Fe.Ol, + 3Zn003 = Fe,(003)3 + SZnCl,. The Fe2(C03)3 together with some hydroxide precipi- tates and the ZnOl^ remains in solution with the rest of the ZnClj. The Fe2(003)3 usually decomposes with some rapidity into Fe,03 thus: Fe,(C03)3 = Fe,03 + SCO,. The solution is a clear, colorless liquid, odorless, and is used as a disinfecting and antiseptic solution. Zinc Chloride. Zinc/' Chloridum. ZnCl^. — A very deliques- cent salt, rarely used, made by evaporating the solution of zinc chloride. It is used externally as an escharotic, and is often mixed with flour and water to mitigate or regulate its effect. Zinc Phosphide. Zinci Phosphidum. ZUgP^. — Made by con- ducting vapors of phosphorus in current of hydrogen over heated zinc — a dangerous operation. It occurs in crystal- line, brittle fragments, or as grayish powder, insoluble, per- manent in air. Zinc phosphide is preferred by many to phosphorus for internal administration. Dose, .003 to .006 Gm. Aluminum Salts. Aluminiim is one of the most abundant of the metals, and occurs very extensively in rocks and clays. Some com- pounds are made from cryolite, the fluoride of sodium and aluminum, GNaF.Al^Fg, found abundantly in Greenland. Many of the precious stones are aluminum compounds, the metal itself being of considerable value, owing to the diffi- 224 PHARMACEUTICAL AND MEDICAL CHEMISTRY. culty associated with its separation from its compounds. It is only a little more than 2^ times heavier than water^ but yet has all the valuable qualities of iron, with none of its negative properties; it does not tarnish or oxidize in the air, and is only about one-fourth as heavy as iron. Advantage is taken of its lightness in the manufacture of small weights, particularly the grain and smaller divisions of the gramme, and delicate apparatus and articles of ornament. Among the usual methods for isolating it is the reduction of its compounds with metallic sodium or potassium. It is a trivalent or pseudo-triad (AIJ""^ metal; atomic weight, 27; symbol Al. Analytical Reactions. — The alkaline hydroxides pro- duce gelatinous white precipitates, Al2(0H)g, which are sol- uble in excess, excepting in ammonia. The alkali carbon- ates yield a similar precipitate, the OO^ escaping: Al2(S0j3 + 3Na,C03-f 3H,0 = A1,(0H),+ 3^,80, + 3C0,. Am- monium sulphide also precipitates the hydroxides with the evolution of hydrogen sulphide: A1,(S0 J3 + 3(NHJ,S + 6H,0 = A1,(0H), + 3(NHJ,S0, + 3H,S. Alum. Alumen. K,A1,(S0 J,24H,0.— This salt is the type of all the alums, explained in a previous chapter. It is made chiefly from the aluminum silicate in alum-clay by appropriate treatment with sulphuric acid, the addition of potassium sulphate, and allowing the two sulphates to crystallize together with 24 molecules of water. If in place of potassium sulphate the ammonium sulphate is em- ployed, amm 071111711 alum, (NIL^)^A]^{SOJ^24Rfl, is formed. Alum occurs in large octahedral crystals or as white pow- der, is odorless, has sweetish, astringent taste, soluble in water, and effloresces slightly in dry air. Iron, zinc or lead rHARMACEUTICAL AND MEDICAL CHEMISTRY. 225 may be present as impurities in any of the aluminum com- pounds, and may be looked for by the usual tests. Alum is one of the best styptics and astringents we haye. Dried Alum. Alumen Exsiccafum. K,A12(S0J4.— The crys- tallized alum when heated loses its water of crystallization and becomes the official Alumen Exsiccatum. Exsiccated means dried. Alum loses about 45 per cent of its weight in the process of drying, and dried alum is more powerful than tlie hydrous alum in consequence. The loss in weight which a crystallized salt sustains upon drying is easily found from the .molecular weights before and after drying, f.i. alum before drying is K^Al^- (SOJ^24H20, its molecular weight is the sum of the weights of the atoms : 2A1 = 2 X 27 = 54 2K = 2 X 39 = 78 4(S0 J, = 4 X (S = 32 + 40 = 64 =)96 = 384 24H,0 = 24 X (H, = 2 + = 16 =)18 = 432 Molecular weight of alum = 948 Upon drying the 24H2O are expelled; hence there is a loss of 432; then 948 — 432 = 516, the molecular weight of K,A1,(S0.),. To express the loss in percentage it is only necessary to use the rule of three: 948 : 432 : : 100 : x = 45.57 per cent loss. 100 grains of alum would therefore become dried or hurnt alum when the weight would have become reduced to 55 grains. Aluminum Hydrate. Alumini Hydras. K\^{011)^. — Hydrox- 226 PHARMACEUTICAL AND MEDICAL CHEMISTRY. ide would be a better term than hydrate to apply to this drying or absorbing and antacid powder. It is made by precipitating sodium carbonate by alum and thoroughly washing the precipitate with hot water and drying. (See reaction above.) The light white powder thus obtained is permanent in air, odorless and insoluble. It is used but little. Aluminum Sulphate. Alumini Sulphas. K\{^OX.l^B.fi. — The freshly prepared hydroxide is dissolved in dilute sul- phuric acid and the solution allowed to crystallize or granulate. It is antiseptic, and seldom or rarely used in- ternally. Cerium. There is only one cerium salt official, the oxalate, and that is made by a very circumstantial process, necessitated by the association of cerium with the two rare metals lan- thanum and didymium. The cerium compounds when sufficiently purified are precipitated by oxalic acid. Cerium Oxalate. Cerii Oxa/as. 062(0^0^391120. — Is a whitish powder, slightly granular, permanent in the air, odorless, tasteless, insoluble, soluble in hydrochloric acid. Sodium hypochlorite gives a red precipitate in the latter solution, soluble in warm HOI, evolving chlorine. Oxalate of cerium is regarded as almost a specific for checking nausea. Dose, 0.06 to 0.30 Om. Lead Salts. Of the several combinations in which lead is found in nature, the sulphide, or galena, is the one usually chosen as the source of the metal and its salts. Galena occurs very PHARMACEUTICAL AND MEDICAL CHEMISTRY. 227 abundantly in this country and is usually associated with silver, though often found in the free state. The metal is extracted from the ore by roasting first in contact with and in the latter part of the process without, access of air, or by melting with charcoal. Lead is a bluish -white, soft, malleable metal, with a per- ceptible taste, and an odor when rubbed, little acted upon by air, but soluble to a slight extent in very pure water, becoming a hydroxide. Water thus impregnated is very poisonous, and increases in its toxic qualities if the hydrox- ide becomes changed, through the presence of carbon diox- ide, into the more soluble bicarbonate. A knowledge of this fact should prompt the utmost carefulness in the use of lead pipe or leaden vessels of any kind for purposes where presence of lead might entail disastrous results. There are numerous cases on record where poisoning was traced to lead in drinking-water or in mineral-waters drawn through leaden pipes. Magnesium sulphate or sodium, or highly diluted sulphuric acid, are chemical antidotes. Lead is a dyad ; atomic weight, 206.4 ; sp. gr.. 11.45; symbol, Pb. AiyfALYTiCAL Keactions. — 1. Sulphuretted hydrogen produces a black precipitate of the sulphide, PbS. Very minute quantities may be detected by this test. 2. Any soluble iodide gives a characteristic yellow preci- pitate of lead iodide, Pbl^. 3. Soluble sulphates precipitate the insoluble lead sul- phate, PbSO,. 4. Soluble carbonates precipitate the insoluble lead car- bonate, PbCOg. Lead Oxide. Plumbi Oxidum. PbO.— Litharge is one of the five oxides of lead, and is made by roasting the lead ores 238 PHARMACEUTICAL A:N"D MEDICAL CHEMISTRY. in a reverberatory furnace. It is often obtained as a by- product in the extraction of silver from argentiferous ga- lena. Litharge is a heavy yellowish or reddish powder^ in- soluble, colorless, tasteless, remaining unchanged in the air. It may contain as impurities traces of alkalies and al- kaline earths, zinc and carbonate. From it most of the other salts of lead are prepared. . Lead Acetate. Plumbi Acetas. Pb(C,H30J,.3H,0.— This is the most important of the lead salts used in pharmacy; it is easily made by heating together a mixture of lead oxide and acetic acid: PbO -h SHC.HgO,^ Pb(0,H30J, + 3H,0. If the acetic acid is not pure the salt usually has a smoky odor which does not disappear rapidly upon recrys- tallization. The commercial salt should not be used in pharmacy, but only that made from the purest acetic acid. Sugar of lead, as the salt is most frequently called, occurs in colorless, shining, prismatic crystals or scales, is soluble in alcohol and water, has faintly acetous odor and astringent taste, and absorbs carbonic acid from the air. The latter is the cause of the turbidity noticed in solutions of the salt. This turbidity may be removed by the addition of a little acetic acid. Acetate of lead is astringent, and is used ex- ternally in solution as a sedative wash, often combined with laudanum. Solution of Lead Subacetate. Liquor Plumbi Subacetatis. — This aqueous liquid, containing about 25 per cent of lead subacetate, approximately Fhfi{CJi^O^)^, is obtained by boiling together lead oxide and lead acetate in water pre- viously boiled to expel all its dissolved air. In the opera- tion air should be excluded as much as possible to prevent the formation of carbonate. The salt in solution is not a definite compound, but consists of several oxyacetates in PHARMACEUTICAL AKD MEDICAL CHEMISTRY. 229 variable proportions. The reaction between the oxide and acetate is sometimes expressed in this wise: 3Fh{CJlfi^)^ + 3PbO = Pb,0{C,H,OJ..Pb30,(C,H30J, GpULARD^s Extract is a term often applied to the solu- tion. It is a clear, colorless liquid of alkaline reaction, usually depositing a sediment after contact with air, which consists of carbonate. The solution is never used inter- nally; but externally it is preferred to a solution of the acetate. Diluted Solution of Lead Subacetate. Liquor Plumbi Sub- acetafis Dilutus. — Lead- WATER. — A solution of 3 parts Gon- ial d's extract in 97 of boiled water which has been cooled. The formation of opalescence in the solution is due to the carbonic acid gas in the water. It may be dispelled with a few drops of acetic acid. Lead-water has at times been mistaken for lime-water , and serious results have attended the mistakes. It has been suggested that the opalescence in lead water be allowed to remain, as a mark of distinc- tion from lime water, which should always be dispensed as a clear and transparent solution. Lead-water is used ex- ternally as a cooling and soothing application. Liniment of Lead Subacetate. — This sedative and cool- ing application to burns, which is a mixture of 40 parts of solution subacetate lead and 60 parts cottonseed oil, has been dismissed from the 1890 U. S. P. Cerate of Lead Subacetate. Ceratum Plumbi Subacetatis. — GouLARD^s Cerate. — Twenty parts of solution subacetate lead are incorporated with 80 parts of camphor cerate; the resulting preparation has the qualities of the solation in ointment form. The addition of a few drops of acetic acid prevents the cerate from becoming yellow. Lead-Plaster. Emplastrum Plumbi. — Diachylon or lead-plas- 230 PHAEMACEUTICAL AND MEDICAL CHEMISTRY. ter is a chemical compound, an oleate of lead, prepared by boiling together lead oxide and olive oil. Olive oil contains, among other fatty bodies, the oleate of propenyl, 03H^(Cja- HasOJg, which reacts upon the PbO thus: 2C3H,(0,,H330,) + 3PbO + 3H,0 = 3Pb(C,3H330J, (oleate of lead or lead- plaster) -|- 2C3H^(OH)3 (glycerin). The lead-plaster is a by-product in the manufacture of glycerin. Lead-plaster is chiefly valuable as a base for many of the medicinal plasters. Diachylon Ointment. — Lead-plaster reduced to the consistency of an ointment with olive oil constitutes the diachylon ointment. It is perfumed with oil of lavender. Lead Nitrate. Plumbi Nitras. Pb(N03)2.— Lead nitrate is readily obtained by dissolving lad oxide in nitric acid by means of heat, filtering, evaporating and crystallizing: PbO + 2HNO3 = Pb(]Sr03), + H,0. It is in form of trans- parent or whitish, nearly opaque crystals, permanent in air, soluble in water, odorless, astringent taste. It is used mainly in making the lead iodide, though at times it is used externally. Lead Iodide. Plumbi lodidum. Pbl,. — A solution of lead nitrate is precipitated by a solution of a soluble iodide, potassium iodide usually, and the precipitate washed and dried. Pb(N03), + 2KI = Pbl, + 2KNO3. Lead iodide is a heavy, bright-yellowish powder, unchanged in air, odorless, tasteless, and practically insoluble in alcohol and water, but soluble in solution of ammonium chloride and in solution of the acetates of the alkalies. The iodide is sometimes given internally in doses of 0.03 to 0.10 Gm., but it is chiefly used in form of oint- ment. Ointment of Lead Iodide. Unguentum Plumbi /odidi.—Ten PHARMACEUTICAL AND MEDICAL CHEMISTRY. 23l parts of lead iodide are incorporated with 90 parts of ben- zoinated lard to obtain the ointment of lead iodide. Lead Carbonate. Plumbi Carbonas. (PbC03),Pb(0H),.— White-Lead. — The carbonate is made on a very extensiv9 scale for use as a pigment by exposing metallic lead to the action of the air, acetic acid vapors and decaying matter which yields carbonic acid gas. It may be made by preci- pitating a solution of lead nitrate with sodium carbonate, washing and drying the precipitate: Pb(N03)2 + Na^OOg = PbCOg + SNaXOg. It is not a true carbonate, but con- tains, as its formula indicates, a certain quantity of hydrox- ide. Its chief use is in the arts as a base for paints. In pharmacy it is used externally in form of ointment, and very often injudiciously in cosmetics and hair-restorers. Ointment of Lead Carbonate consists of 10 parts of lead carbonate and 90 of benzoinated lard thoroughly incorpo- rated ; it is used externally to reduce inflammation. Copper Salts. Copper is found in a native state, but it also occurs as oxide, sulphide, arsenate, carbonate, sulphate, etc. It is of a red color; specific gravity, 8.95 to 9, and is more valu- able in the arts and manufactures than in pharmacy. It is a dyad; atomic weight, 63.18; and it forms two official salts, the sulphate and acetate; symbol, Cu. Analytical Reactions. — 1. H^S produces a black pre- cipitate of the sulphide, CuS. 2. Red cupric ferrocyanide is precipitated from copper solutions by ferrocyanide of potassium. 3. Ammonia-water gives deep-blue color with dilute so- lutions of copper salts and a blue precipitate in strong solutions. 232 PHARMACEUTICAL AKD MEDICAL CHEMISTRY. 4. Metallic zinc or iron is coated with copper in solutions of copper, an equivalent quantity of the zinc or iron going into solution. Copper Sulphate. Cupri Sulphas. CuSO^SH^O. — Blue Vit- riol PR Blue-stoi^e. — This salt is made on a large scale by dissolving waste copper in warm dilute sulphuric acid, evaporating, crystallizing and purifying by recrystalliza- tion. It is in form of large, translucent, deep-blue crys- tals, efflorescent, odorless, nauseous taste, soluble in water, insoluble in alcohol. Internally in doses of 0.30 G-m. it is emetic, in 0.03 Gm. doses tonic; externally its solution is a good stimulating wash. It is largely used as a disinfectant together with sulphate of iron. The impurities sometimes present are iron, alkalies and alkaline earths, lead, zinc and arsenic. Copper Acetate, Cu(C2H30„)2HoO. — Of several methods of preparing this salt, that in which lead acetate is em- ployed in solution with copper sulphate is the most conven- ient one: CuSO, + Pb(C,H,0,), = PbSO, + Cu(C,H30J,. The lead solution should be concentrated. The solu- tion of the acetate is filtered and allowed to crystallize, when it yields deep-green prismatic crystals which are odorless, efflorescent, soluble in water, and only slightly soluble in alcohol. The salt is sometimes, though errone- ously, called verdigris. It is used in much the same manner as the sulphate is, but is not any longer official. Mercury and Its Salts. Mercury, or quicksilver, is one of the only two liquid elements, bromine being the other, known to chemists. The sulphide, or cinnabar, HgS, is its most abundant natural compound, and from it usually by heating it in fur- PHARMACEUTICAL AN^D MEDICAL CHEMISTET. 233 naces with access of air, the metal itself is obtained. The metal is volatile, and, becoming disengaged from the sul- phur, which burns and escapes as SO2 in the process, its vapors are conducted into suitable chambers and there condensed : HgS -j- 0^ = Hg -f SO,. There are other processes of extraction, but they are more complicated and little used. The extensive mines of California yield at present more than enough to supply the markets of this country, and considerable quantities are exported. There are very rich mines in Spain also which have been worked from pre-Christian times, and are still pro- ductive. The mercury salts are a very important class of com- pounds, pharmaceutically and chemically, but the chief and most extended use of the metal is found in the arts — in the manufacture of thermometers, barometers, mirrors, in mining gold and silver by amalgamation, and in mak- ing the pigment vermilion, etc. For pharmaceutical pur- poses the crude mercury is purified, preferably by distilla- tion, or by squeezing through chamois leather. The latter method removes only suspended matter or mechani- cal impurities, as traces of oxide or water. Mercury is a silver-white, bright, liquid metal, odorless, tasteless, in- soluble except in some acids; it is slightly volatile at ordin- ary temperatures; its volatility increases with the tempera- ture, being greatest at its boiling-point, 662° F., and least at its freezing-point, — 40° F. Mercury sometimes contains tin or other metals as impurities, and when it does, globules dropped upon white paper do not retain their globular form nor roll about freely, and frequently leave traces or streaks on the paper. The metal should have a bright surface and should be dry. 234 PHARMACEUTICAL AND MEDICAL CHEMISTRY. Mercury has an atomic weight of 200 (exactly, 199.80) and forms two series of compounds, the mercuwus and the mercuric. It is a dyad, and in the mercuric salts a single atom has bivalent value, while in the mercurous salts two atoms together have a combining value of two. The two chlorides will illustrate this by their graphic formulas : Mercuric Chloride, HgCla. .01 H < 01 Mercurous Chloride, HgaCla. Hg-01 Hg-01 The base in the mercuric salts is always a single atom of mercury, Hg, while the base in the mercurows salts always consists of tvw atoms — Hg^. In the mercurous com- pounds one bond from 'each of two atoms of mercury neu- tralizes or combines with each other, leaving the one other bond from each atom to unite with a radical equivalent to two bonds. Important Reactions of Compounds of Mercury. Hydrochloric acid gives : Ammonia -water gives : Hydrogen sulpliide gives : Petassium iodide gives : Potassium hydrox- ide gives : With Mercuric Salts in Solution. No precipitate, HgClg soluble (corrosive sublimate). White precipitate (call- ed " white precipi- tate ") NHsHgCl. Black precipitate, HgS (sulphide). Red precipitate, Hglg (red mercuric iodide). Yellow precipitate, HgO (yellow oxide). With Mercurous Salts. White precipitate, in- soluble, Hg2Cl2 (cal- omel). Black precipitate, NH^Hg^Cl. Black precipitate, HgaS (sulphide). Green or yellow pre- cipitate, Hgala. Nearly black precip- itate, HgaO. PHARMACEUTICAL AND MEDICAL CHEMISTRY. 335 All the salts of mercury are poisonous, but the mercuric are far more so than the mercuro?^.^. There is no specific antidote for salts of mercury, but white of egg and other albuminous substances have proved of some value by coagu- lating the soluble salts of mercury when administered in time. Free use should be made of emetics or the stomach- pump, and eggs and milk given freely. A piece of bright copper or a bright penny (made so by dipping into nitric acid) becomes coated with mercury in solutions of mercury salts, an equivalent quantity of copper going into solution. Mercury dissolved in hot and concentrated nitric acid yields the mercuric nitrate, but if the nitric acid is diluted and cold, the oxidation is incomplete and the mercurous nitrate is formed. Preparations Containing Metallic Mercury. No other element is used so largely in the metallic state in medicine and pharmacy as mercury, and the United States Pharmacopoeia recognizes five such preparations. Mass of Mercury. Massa Hydrargyri. — Blue Pill or Blue Mass. — Mercury is rubbed or triturated with honey of rose and glycerin until globules are no longer visible under a magnifying glass of ten-diameter power — that is, until the metal is thoroughly subdivided and incorporated with the excipients. This work is laborious and tedious when executed with pestle and mortar, and resort is profitably had to machinery, especially when manufacturing it on the large scale, as is done at present. "When thorough subdivi- sion has been accomplished, powdered licorice and marsh- mallow are added to make a mass of a pilular consistence. This preparation contains 33 per cent of metallic mer- 236 PHARMACEUTICAL AKD MEDICAL CHEMISTRY. cury, and is usually given in doses up to 0.66 to 1.00 gm. as a purgative in bilious affections, its administration to be followed by a mild saline cathartic. Mercurial Ointment. Unguentum Hydrargyria — Blue Oint- MEKT. — Mercury is extinguished or killed, as the process of subdividing mercury by trituration is often called, with previously prepared mercurial ointment, or, as the 1890 U. S. P. directs, with oleate of mercury, and incorporating with it melted lard and suet. This ointment is a conven- ient form for the external administration of mercury, and is largely used. It contains 50 per cent of mercury. Mercurial Plaster. Emp/astrum Hydrargyri. — This plaster is employed in medicine when it is not convenient to use the ointment. It contains 30 per cent of mercury extin- guished with oleate of mercury and incorporated with lead-plaster. Ammoniac Plaster with Mercury. Emplastrum Ammoniac cum Hydrargyro. — This plaster is somewhat milder than the above, containing only 18 per cent of mercury extin- guished with oleate of mercury, besides lead-plaster. The ammoniac is previously emulsified witli dilute acetic acid. Mercury with Chalk. Hydrargyrum cum Creta. Is a prepara- tion of metallic mercury in powder form, and serves the same purpose as the mass does. Mercury, clarified honey and chalk are triturated until the mercury is no longer visible under a ten-diameter lens, the trituration being facilitated by the addition of a small quantity of water. Lastly enough chalk is added to make the preparation con- tain 38 per cent strength of mercury, and the whole thor- oughly dried. The preparation should be kept in well- stoppered bottles protected from light to prevent the formation of traces of oxide of mercury. I PHARMACEUTICAL Al^r> MEDICAL CHEMISTRY. 237 Salts of Mercury. The salts of mercury should be kept in dark, amber- colored, well-stoppered bottles, protected from light. When handling them it should be borne in mind that nearly all them are very poisonous. Corrosive Mercuric Chloride. Hydrargyri Chloridum Corrosivum. HgOl^.— Corrosive Sublimate, Corrosive Chloride of Mercury. — This, one of the most poisonous and valuable of the salts of mercury, is made from mercuric sulphate by subliming it with common salt — e.g., HgSO^ + 2E'a01 = HgOl, + N%SO,. The HgSO^ is obtained from metallic mercury by boil- ing with strong sulphuric acid : 2H2SO4 + Hg = HgSO^ + SO, + 2H,0. The corrosive chloride occurs in crystalline masses (to distinguish it from calomel, which is in powder form), is odorless, has persistent metallic taste, is permanent in air, soluble in water, alcohol and ether, and volatilizes when heated to a high degree, yielding vapors which are ex- tremely poisonous. Arsenic is sometimes detected as a contamination. Cor- rosive sublimate is one of the most powerful and exten- sively employed antiseptics. It has come into wide use of late in antiseptic surgery, proving the most valuable and powerful antiseptic and disinfectant in use. Its other medicinal applications are numerous. Internally it is very valuable as an alterative; its dose ranges from 0.001 to 0.005 Gm. The serious consequences which may attend carelessness in the handling of this salt should prompt extreme caution in its use. Mild Mercurous Chloride. Hydrargyri Chloridum Mite. — SuB- 238 PHARMACEUTICAL AND MEDICAL CHEMISTRY. CHLORIDE OF MeRCURY, MiLD ChLORIDE OF MeRCURY, Calomel. — Merciirous sulphate, Hg^SO^, mixed with com- mon salt and heated, produces a sublimate of the mercu- rous chloride: Hg.SO, + 2NaCl = Hg.Cl, + Na.SO,. The mercuric sulphate when rubbed with another atom of mercury becomes the mercurous sulphate: HgSO^ -f Hg = Hg,SO, ^ The sublimate of calomel is obtained in powder form by rapid and sudden cooling of the vapors; slower cooling yields the sublimate in mass form. Calomel, the Hydrar- gyri Chloriclum Mite of the Pharmacopoeia, is in form of a white, heavy, impalpable powder [Hydrargyri Chloridum Cor?^osivum is kept in form of crystalline masses), and is odorless, tasteless, wholly insoluble in ordinary solvents, and quickly blackened by ammonia- water. It is ^^er- manent in the air, but volatilizes at high temperatures; it may be reduced to metallic mercury by heating with dried sodium carbonate in a long test-tube. On account of the similarity in the processes for making both the mild and corrosive chloride, the former may con- tain traces of the latter, a possibility which must be strenuously guarded against. Mercuric chloride may be detected in calomel by washing the latter with alcohol or ether, which dissolves out any corrosive chloride that might be present, and testing the filtrate for chloride with solution silver nitrate, and for mercury with H^S. Calo- mel is totally insoluble in ordinary solvents, and water or alcohol, after having been agitated with it, should remain unaffected by any reagent. Ammoniated Mercury, which resembles calomel in appearance, is soluble in acetic acid, from which solution it may be precipitated as the black sulphide with H^S gas. PHARMACEUTICAL AN"D MEDICAL CHEMISTRY. 239 The last three tests should be applied before putting the calomel upon the dispensing-counter. Owing to its insolubility in the system its action is largely mechanical, and its dose comparatively large, ranging from .030 to 1.00 Gm. In small doses, from .006 to .030 Gm., it is alterative and stimulating to the liver; in large doses purgative. It was at one time believed that sodium chloride converted calomel partly into corrosive sublimate, but ex- tensive investigation and trials have failed to verify this. The pharmacist should nevertheless be vigilant to prevent its being dispensed with salts concerning whose chemical action toward it there may be a doubt. Calomel entei's into the Compound Antimony Pills, and into the Compound Cathartic Pills. Red Mercuric Iodide. Hydrargyri lodidum Rubrum. Hgl^. — Ebd Mercuric Iodide, Bin'iodide of Mercury. — Obtained by adding potassium iodide to mercuric chloride in solu- tion, and thoroughly washing and drying the precipitate at a low temperature. The decomposition is represented by the following equation : HgCl, + 2KI = Hgl, + 2KC1. As the red iodide is soluble in excess of potassium iodide solution, care should be taken to avoid an excess. It is a scarlet-red crystalline powder, odorless, tasteless, almost in- soluble in water, slightly soluble in alcohol and permanent in the air. Water shaken with the salt should not be affected by solution of nitrate of silver — test for the absence of soluble iodide or chloride. Mercuric iodide in medicine is given internally chiefly as an alterative in syphilis; dose, .002 to .015 Gm. Yellow Mercurous Iodide. Hydrargyn lodidum Flavum. Hg J^- Green Mercurous Iodide, Protoiodide of Mercury. — Iodine and mercury are rubbed together in equivalent 240 PHARMACEUTICAL AND MEDICAL CHEMISTRY. quantities in presence of alcohol, and when combination is completed washed with alcohol. The alcohol prevents by its evaporation the elevation of temperature which the chemical union induces ; alcoliol is employed to wash the finished salt because it dissolves out the traces of mer- curic iodide which are usually formed, and which are much more poisonous than the mercurous iodide : Hg^ + 1^ = Hgjj- '-The JJ. S. P. directs the salt to be made by precipitating mercurous nitrate solution by potassium iodide solution: Hg,(N03), + 2KI = HgJ, -f 2KNO3. The green or yellow iodide is so called because it has a greenish-yellow color; it becomes quite yellow when ex- posed to air, wherefore it is termed yellow iodide in the 17. S. P. It is practically insoluble in water, insoluble in alcohol, odorless, tasteless, and becomes darker in color if exposed to light for a long time. The medical properties of the yellow iodide are the same as those of the red, but because of its milder action it is sometimes preferred to the latter salt. The dose is some- what larger, being often given in doses of .065 Gm. Yellow Mercuric Oxide. Hydrargyri Oxidum Flavum. HgO. — Made by adding solution of mercuric chloride to solution of soda and setting aside for several hours, when the pre- cipitate formed is thoroughlj'' washed with distilled water and dried between blotting-paper: HgCl^ -j- 2NaOH = HgO + 2Na01 + H,0. Yellow mercuric oxide is a light, orange-yellow powder, becoming darker when exposed to light, insoluble in water, tasteless and odorless. It has the same composition as the red oxide. It is chiefly used for the ointment and for the oleate of mercury. Ointment of Yellow Mercuric Oxide. Unguentum Hydrargyri PHARMACEUTICAL AKD MEDICAL CHEMISTRY. 241 Oxidi Flavi. — Contains 10 parts of the yellow oxide thor- oughly incorporated with 90 of simple ointment. It and the ointment of red oxide mercury are used medicinally in similar indications. Oleate of Mercury. 0/eatum Hydrargyri. — Made by dissolving 20 parts of yellow mercuric oxide in 80 of oleic acid. Chem- ical combination takes place as follows: HgO-l-2HCjaHg302 (oleic acid) = ^g{Q^Jl^fi^^ (oleate mercury) -\- H^O. Heat should not be employed. The oleate is employed when it is not convenient to use the ointment. When kept for some time metallic mercury separates, hence the preparation should never be kept long. Red Mercuric Oxide. Hydrargyri Oxidum Rub rum. HgO. — Mercuric Oxide, Red Precipitate. — This oxide differs from the yellow probably only in color ; chemically it is the same. It may be made by decomposing mercuric nitrate with heat, e.g. : 2H,(N03) 2 + heat = 2HgO + 4^0, + 0,. The salt is usually in heavy, orange-red crystalline pow- der, sometimes in scales, odorless, tasteless, insoluble in alco- hol and water, soluble in nitric or hydrochloric acid. It differs from the yellow oxide in not forming a mercuric oxalate of a white color, as that does, when digested on water bath with solution of oxalic acid. Ointment of Red Mercuric Oxide. Unguentum Hydrargyri Oxidi Rubri. — This ointment is the principal form in which the red oxide is used. It contains 10 per cent red oxide rubbed smooth with castor oil and incorporated with simple oint- ment; it is much employed by ophthalmologists and derma- tologists, and is popularly known as red precipitate ointment. It should not be dispensed except upon a physician's order. Mercuric Cyanide. Hydrargyri Cyanidum. HgCy^ or Hg(CN3). —This salt of mercury is prepared by passing hydrocyanic 242 PHARMACEUTICAL AND MEDJCAL CHEMISTRY. acid gas into mercuric oxide: HgO + ^HCN = Hg(CN)2 -j- H^O. The hydrocyanic acid is made in the process by the action of sulphuric acid upon ferrocyanide of potassium. The cyanide occurs as colorless or white prismatic crys- tals darkening on exposure to light; it is odorless, of a bitter taste, soluble in alcohol and water, and exceedingly poisonous. It should be tested for mercuric chloride with iodide of potassium. It is alterative; dose, .003 to .005 Gm. Ammoniated Mercury. Hydrargyrum Ammoniatum. Hg^H^Ol. — White Precipitate, Mercur-ammonium Chloride. — Obtained by adding solution of mercuric chloride to am- monia-water and washing and drying the precipitate: 2NH,H0 + HgOl, = NH^Ol + HgNH.Cl + 2H,0. There are numerous mercur-ammonium compounds, but the official one probably is as above. White precipitate occurs in form of white powder, odorless, tasteless, insoluble in alcohol or water, and permanent in air. It is very poisonous, and care should be taken not to mistake it for calomel, which resembles it in appearance and physical properties. Ointment of Ammoniated Mercury. Unguentum Hydrargyri Am- moniati. — Ammoniated mercury is never used internally, and only seldom externally in form of ointment. The oint- ment contains 10 parts ammoniated mercury and 90 of benzoinated lard, and is employed in various skin-diseases. Yellow Mercuric Sulphate. Hydrargyri Subsulphas Flavus. Hg(HgO),SO, or HgSO,2HgO.— Turpeth Mineral, Ba- sic Sulphate Mercury. — Mercuric sulphate prepared as above shown is added to boiling water, when the yellow basic sulphate separates as a precipitate, while some acid mercuric sulphate which is formed remains in solution. Turpeth mineral is a heavy, lemon-yellow powder, odor- less, tasteless, insoluble in water and permanent in air. It PHARMACEUTICAL AN"D MEDICAL CHEMISTRY. 243 should be free from mercurons salt. If this is absent the salt is soluble in 20 parts of hydrochloric acid. The salt is rarely used — occasionally it is given as an emetic, in doses of .065 to .195 Gm., to children suffering from croup. Red Mercuric Sulphide. HydrargyH Sulphidum Rubrum. HgS. — Mercuric Sulphide, CiiTNABAr., Vermilion^. — Mer- cury and sulphur are fused and the mass powdered and sublimed. Much of the finest vermilion in commerce comes from China, though some is made in this country. It is a brilliant, dark-red or scarlet powder, odorless, insoluble, and permanent in the air. It is used most extensively in the arts as a pigment; in medicine it is used but little, and is not any longer oflficial. Solution of Mercuric Nitrate. Liquor H yd rargyri Nitraiis. — A liquid containing 60 per cent of mercuric nitrate, Hg(N03)2, together with about 11 per cent of free nitric acid. It is made by dissolving red oxide of mercury in diluted nitric acid. It is a clear, colorless liquid of a specific gravity of 2.10, miscible with alcohol or water. The solution is very corrosive and poisonous, and is employed principally in the treatment of ulcers and malignant growths as a cau- terant. Citrine Ointment of Mercuric Nitrate. Unguentum H yd rargyri Nitratis. — CiTRiNE OiNTMENT. — Made by thoroughly incor- porating solution of mercuric nitrate with a mixture of lard oil and nitric acid. It is employed externally in skin diseases and in some diseases of the eyes. 244 PHARMACEUTICAL AKD MEDICAL CHEMISTRY. The Silver Salts. Silver occurs chiefly in the metallic state in nature, but its sulphide is also found abundantly either alone or asso- ciated with sulphide of lead. The chloride, horn-silver, is also found in large enough quantities to make it profitable to extract the silver. Silver is of a brilliant whiteness, very malleable and ductile, and used in pharmacy principally in making the nitrate, from which, in turn, all the other official salts are prepared. It has a specific gravity of 10.5, and is applied to a great variety of purposes in the arts. Coin-silver contains copper to give it greater hardness. Silver is a monad and has an atomic weight of 107.66; sym- bol, Ag {arge7itu7n). Metallic silver in form of silver-leaf is used by pharmacists for coating pills. The silver salts should be kept in well-stoppered bottles protected from light. Analytical Eeactioks. — 1. Silver is soluble in nitric acid, forming the nitrate, with the evolution of '^fi^ vapors. 2. Chlorides in solution produce a curdy white precipi- tate of silver chlorine, which is insoluble in nitric acid, but readily soluble in excess of ammonia-water. 3. The alkalies give a brownish precipitate of silver oxide. This precipitate should be handled carefully, as it easily explodes when rubbed in contact with readily oxidizable substances. 4. Metallic silver is blackened by hydrogen or ammonium sulphide, and solutions of silver salts give black precipitates with the same reagents. 5. Solutions of silver salts in contact with the skin turn the latter black, owing to the reduction of silver to the metallic state. I PHARMACEUTICAL AND MEDICAL CHEMISTRY. 245 Silver Nitrate. Argenti Nitras. AgNOg. — This, the most valuable of the silver salts^ is made by dissolving pure silver (not coin-silver, which contains copper) in nitric acid, evaporating to dryness, and increasing the heat until the mass melts to expel all nitric vapors. When cooled the mass is dissolved in water and crystals allowed to form in the filtered solution. Any copper which may have been present is thus oxidized and remains on the fil- ter. 3Ag, + 8HNO3 = 6AgN03 + N,0, + 4H,0. The nitrate is in form of heavy tubular, transparent, colorless fusible crystals, soluble in Avater, odorless, of metallic taste, and becoming gray or black upon exposure to light in contact with organic matter. Metallic im^nirities are detected by removing all the silver with hydrochloric acid and evaporating the filtrate to dryness — a fixed residue would indicate the presence of other metals. Sodium nitrate is sometimes thus detected, and if present is usually an adulteration. Copper, if present, gives blue solution with ammonia- water. Silver nitrate is used externally as a caustic and escharotic. Great care should attend its internal administration, as it is very poisonous. Antidote. — Common salt produces the insoluble silver chloride : AgNO, + NaCl = AgCl + NaNOg. Emetics should follow. Fused Silver Nitrate. Argent/' Nifras Fusus. AgNO^ + AgCl. Lunar Caustic. — Made by melting silver nitrate crystals at as low a temperature as possible and adding 4 per cent of hydrochloric acid, heating until the nitric vapors are dis- pelled, and casting into moulds. The HCl produces AgCl, which, though insoluble, renders the nitrate much less brittle and more tenacious. The fused or moulded silver nitrate is in form of hard, white, solid pencils, having the same proper- 246 PHAKMACEUTICAL AND MEDICAL CHEMISTRY. ties tliat the crystals have, excepting that it is not wholly soluble in water, the chloride, amounting to about 5 per cent., remaining undissolved. Diluted Silver Nitrate. Argent/ Nitras Dilutus. AgNO^ -f KNO3. — Diluted or mitigated silver nitrate is made by melting together equal parts of silver and potassium nitrates in a porcelain crucible and pouring into moulds. This preparation is used whenever a milder caustic than the pure silver nitrate is desired. Its properties are the same as those of the undiluted nitrate, only less power- ful. Silver Cyanide. Argenti Cyanidum. AgCN. — Obtained by adding solution of potassium cyanide to solution of nitrate of silver : KgSO, + KCN = AgCN + KNO3. The potas- sium nitrate formed is removed by filtration and the wash- ing of the precipitate. The salt is a white, insoluble powder, permanent in dry air, and becoming brown or black by exposure to light and organic matter. It may also be made by passing hydro- cyanic gas into solution of silver nitrate. Its sole use is in the extemporaneous preparation of hy- drocyanic acid, which is made by bringing together pre- scribed quantities of silver cyanide, hydrochloric acid and water, allowing the precipitated silver chloride to sub- side, when the solution of the acid is poured off. The latter constitutes the official hydrocyanic acid, which con- tains 2 per cent. HON. This acid is classed among the organic acids. Silver Oxide. Argenti Oxidum. Ag^O. — A solution of silver nitrate is treated with caustic potassa solution, and the precipitate thoroughly washed and dried : 2AgN03 + 2K0H - Ag^O + 2KNO3 4- H,0. Silver oxide is a heavy. PHARMACEUTICAL AND MEDICAL CHEMISTRY. 247 nearly black, and almost insoluble powder. When tritu- rated with organic or easily oxidizable bodies it is liable to cause explosion, owing to the readiness with which it parts with its oxygen. It should not be brought in contact with ammonia. Pills of the oxide frequently explode. Silver Iodide. Argent! lodidum. Agl. — Potassium iodide and silver nitrate produce silver iodide and potassium nitrate. AgNOg -f KI = Agl + KNO3. The iodide is a light, yellow powder, insoluble, odorless and tasteless. If pure it is not changed by light, but it generally turns greenish-yellow in time. Iron and its Salts. Iron furnishes a greater number of official salts and preparations than any other metal, and its salts are among the most important in pharmacy and medicine. It is hard, tenacious, ductile, malleable, grayish white, specific gravity 7.76, and oxidizes in moist air. Iron can be made to burn in oxygen. It unites with most of the metals and non-metals, forming two classes of compounds, the ferrous and the ferric. In the former it has two bonds and in the latter four but only three are capable of unit- ing with bonds of other elements. For illustration : /Ol Ferrous chloride, FeCL or Fe^ ^01 The iron has two bonds. Fe^Cl Ferric chloride, Fe.Cl, or ! q} Fe^Ol \oi 248 PHAEMACEUTICAL Ai^D MEDICAL CHEMISTRY. Here one atom of iron has four bonds, but one from eacli of two atoms combines with or neutralizes each other, so that huo atoms together have six bonds which will unite with the bonds of other elements. Atomic weight, 56. Symbol, Fe {ferrum). Sources. — Iron occurs very abundantly and is widely distributed in nature. Native iron is only found in me- teors or shooting stars. The chief sources of iron are fer- ric oxide, Fe^Og , and magnetic oxide, Fe304(or FeO-Fe^Og), both of which occur in a variety of forms; the carbonate, FeCOg , and the sulphides, of which there are also a great variety, from the FeS to the Fe,Sg. The sulphate and phosphate are also found. Important Analytical Reactions of Iron Salts. Reagent. Ferrocyanide potassium, K4FeCy6. Ferricyanide potassium, KsFeCye, o r KeFe^Cyia. Ammonia-water, NH4OH. Ammonium sul- phide, (NH4)2S. Sulphocyanide potassium, KCyS. Tannic acid. With Ferrous Salts. Potassium feirous-ferrocya- nide, KsFeFeCye. Nearly white, turning blue in air. Everitt's salt. Ferrous ferricyanide, Fe3(FeCy6)2. Dark blue. Turnbull's blue. (This is a very valuable test for detecting ferrous in ferric salts.) Ferrous hydroxide, Fe(0H)2. White, turning through green, etc., to brown, be- coming ferric. Ferrous sulphide, FeS. Black precipitate. No change. No change at once. With Ferric Salts. Ferric ferrocyanide precipitate, F e 4 - (FeCye)^. Deep blue color, Prus- sian blue. No precipitate, but greenish color. Fe2(FeCy6)2. Ferric hydroxide, Fe2(OH)6, brown magma. Ferrous sulphide, FeS, black precipi- tate. The ferric becomes reduced to ferrous salt. Intensely red solution of ferric sulphocy- anide, Fe,(CyS)6. Blue-black precipi- tate of ferric tan- nate. I PHARMACEUTICAL AND MEDICAL CHEMISTRY. 249 In the study of the long list of iron salts it is again con- venient to follow the order of derivation, as given below : First Series. Iron, metallic. Iodide, saccharated. Iodide, syrup. Lactate, salt. Chloride, salt. Chloride, solution. Chloride, tincture. Acetate iron and ammonium. Sulphate, crystals. Second Series. Sulphate, precipitated. Sulphate, dried. Pills aloes and iron. Carbonate, saccharated. Carbonate, mass. Carbonate, pills. Keduced iron. Iodide pills. Compound iron mixture. Hypophosphite, salt. Subsulphate, solution. Tersulphate, solution. Third Series. Sulphate iron and ammonium, double salt. Valerianate, salt. Hydrated oxide of iron and magnesia. Hydrated oxide, magma. 250 PHABMACEUTICAL AI^D MEDICAL CHEMISTRY. Fourth Series. Hydrated oxide, dried, troches. Hydrated oxide, dried, plaster. Acetate, solution. Nitrate, solution. Tartrate iron and ammonium, scales. Tartrate iron and potassium, scales. Citrate, solution. Citrate, scales. Phosphate, soluble, scales. Phosphate iron, quinine and strychnine, syrup. Pyrophosphate, soluble, salts. Citrate iron and quinine, scales. Citrate iron and quiDine, scales, soluble. Citrate iron and ammonium, scales. Citrate, wine. Citrate iron and quinine, wine. Citrate iron and strychnine, scales. By reference to the above arrangement it will be seen that metallic iron furnishes directly or indirectly by deri- vation all the salts and preparations of iron mentioned in the U. S. P. The salts or preparations, or both, in each series are made directly from the salt or preparation lowest in the column above. Thus, for illustration, the solution of the nitrate is made from the hydrated oxide, which is prepared from the solution of the tersulphate; the latter in turn is derived from the crystals of the sulphate, and the sulphate from metallic iron. Or, in other words, among the series made directly from iron, the sulphate is the starting-point for a second series, of which the PHARMACEUTICAL AND MEDICAL CHEMISTRY. 251 solution of the tersulphate yields a third series, among which is the hydrated oxide, from which the fourth series of salts and preparations, including all the scale salts, is made. Iron. — The United States Pharmacopoeia directs that metallic iron should be in the form of fine, bright and non- elastic wire, that form being usually very pure. Saccharated Ferrous Iodide. Ferri lodidum Saccharafum. Fel^. — Iron and iodine are made to react upon each other in presence of water : Fe2 + 21^ = 2Fel2. The green solution of the ferrous iodide is filtered into sugar of milk, and the mixture evaporated to dryness, triturated with more sugar of milk and a little reduced iron, and afterward preserved in small well-stoppered bottles in a dark and cool place. The object of adding the sugar of milk is to preserve the iodide, which is ordinarily very unstable, decomposing easily and becoming colored by the free iodine. The re- duced iron aids in preventing the separation of iodine. Sugar is employed for its preservative properties in a num- ber of other iron preparations, as will presently be seen. The saccharated iodide of iron is a yellowish-white, some- times grayish- white powder, dissolving to a clear solution in water. A brown color would indicate the presence of free iodine and preclude its employment for dispensing pur- poses. Free iodine when present may easily be detected by adding a few drops of gelatinized starch to the aqueous solution — a blue color would indicate its presence. Medicinally the saccharated iodide is used as an alterative and tonic. Dose, 0. 30 gm. It contains 20 per cent Fel,. Syrup of Ferrous Iodide. Syrupus Ferri hdidi. Fel^. — The syrup is made as the above, excepting that instead of add- ing to the solution of ferrous iodide sugar of milk and 252 PHARMACEUTICAL AND MEDICAL CHEMISTRY. evaporating to dryness, simple syrup is added, yielding a preparation having all the properties of the dry saccha- rated iodide in a liquid state. The syrup should be kept exposed to daylight to aid the sugar in preventing the separation of iodine. If iodine does separate, it combines with the water in presence of daylight to form the colorless hydriodic acid, thereby avoiding the formation of a brown color. Syrup of ferrous iodide has a greenish color, and should not be dispensed if of a brownish color. Its dose is 10 to 15 drops, largely diluted with water, to prevent its action upon the enamel of the teeth, which it invariably destroys when in contact for even a short time. The syrup contains 10 per cent, ferrous iodide; specific gravity about 1.353. Ferrous Lactate. Ferri Lactas. Fe(C3H,03),.3H,0.— This ferrous, salt results when iron is dissolved in lactic acid: Ee,+4HC3H,03 = 2Fe(03H,03),+ 2H,. Whenever metallic iron is dissolved in an acid hydrogen is evolved. The solu- tion of the lactate is evaporated and allowed to crystallize, when the salt is obtained as a pale greenish-white crystal- line mass, or, if granulated, in grains. It is soluble in about 40 parts of water, is odorless and has a mild ferru- ginous taste. Medicinally it is used by some in preference to the other forms of iron, as it is believed to be more readily assimilated. Dose, 0.06 to 0.180 Gm. Ferric Chloride. Ferri Chloridum. Fe^Cl,.12H,0.— Obtained by dissolving iron in hydrochloric acid and oxidizing the ferrous chloride so produced to the ferric state with nitric acid, evaporating to dryness, expelling all acid vapors and crystallizing. When iron is acted upon by HCl, the ferrous chloride is produced: Fe, + 4HC1 = FeCl, + 2H,. The latter is oxi- PHARMACEUTICAL Al^D MEDICAL CHEMISTRY. 253 dized to ferric chloride with nitric acid in the presence of more hydrochloric acid. The oxidation may be thus ex- pressed : 6Fe01, + 2HNO3 + 6HC1 = 3Fe,Cl, + N^O, + 4H2O. Here again it will be well to remember that when nitric acid acts as an oxidizing agent, two molecules of it split up into H^O, ^fi^ and 30, and that the oxygen re- moves in this case the hydrogen from hydrochloric acid, leaving the chlorine free to unite with the ferrous chloride. The three atoms of oxygen require six of hydrogen to form water, hence the necessity of taking six molecules of HOI ; the six free hydrogen atoms require six molecules of FeOl, to convert them into Fe^Olg, because one molecule of Fe^Ol^ requires two more atoms of 01 than two molecules of FeOl^ or Fe^Ol^. If two atoms of chlorine oxidize two molecules of FeOl, into Fe^Olg, the six free hydrogen atoms will re- quire three times two FeOl^, or six FeOl^. The '^fi^ escapes in form of reddish fumes, and the one molecule of water from the 2HNO3 added to the three obtained from the six hydrogen atoms from six HOI and the three oxygen atoms from two HNO3 give the four molecules of water, balancing the equation. Ferric chloride is in yellow crystalline pieces, very deli- quescent and hence very soluble in water, also in alcohol and ether. It has an acid reaction, owing to presence of hydrochloric and sometimes nitric acid. Zinc and copper and the fixed alkalies are sometimes present as impurities, together with ferrous salt and oxychloride. Test solution of ferricyanide of potassium does not give a blue color in absence of ferrous chloride. This salt is rarely used inter- nally, the tincture being preferred. Externally it is used as a styptic. Solution of Ferric Chloride. Liquor Ferri Chloridi. Fe^Olg. — 254 PHARMACEUTICAL AND MEDICAL CHEMISTRY. If in making the precedinpj the solution of Fe^Olg is not evaporated, but so adjusted by the addition of water that it contain 37.8 per cent of the anhydrous ferric chloride, the solution of ferric chloride will be the result. It is a reddish-brown liquid, of strongly acid reaction, styptic taste, specific gravity 1.387, miscible with water, alcohol and ether in all proportions. It is used principally to prepare the extensively used tincture chloride iron. Tincture of Ferric Chloride. Tinctura Ferri ChloHdi. Fe^Olg. — This preparation is made by diluting solution of ferric chloride with alcohol and allowing to stand for at least three months before using. It is made so long before using to permit the formation by the action of the free acid present upon the alcohol of certain compound ethers, among which the ethyl chloride predominates. These ethers are believed to have diuretic properties and a peculiar influ- ence upon the urinary passages. Sometimes a brownish precipitate of ferric oxychloride forms upon standing or upon dilution. This is due to not employing enough hy- drochloric acid in the preparation of the solution. The tincture is a clear, brownish liquid of an ethereal odor, styptic taste and acid reaction, and contains about 13.6 per cent of the anhydrous salt. It is the most important liquid preparation of iron. Dose, from 5 to 30 drops, largely diluted with water. Solution of Iron and Ammonium Acetate. Liquor Ferri et Ammonii Acetatis. Fe2(02ll30 Jg.NH^Cl.— Basham's MIXTURE. — Tincture of chloride of iron is added to solution of ammonium acetate containing excess of acetic acid ; mutual decomposition takes place according to the reac- tion, Fe.Ol, + 6NH,C,H30, - Fe,(0,H30,)3 + 6NH,C1. The solution is flavored with aromatic elixir and glycerin PHARMACEUTICAL AND MEDICAL CHEMISTKT. 255 and water added. This solution should be freshly prepared when needed. The not unpleasant taste and its agreeable appearance, as well as its acceptability to the stomach, recommend it to a wider employment. Its dose is from 15 to 30 cc. Ferrous Sulphate. Ferri Sulphas. 'EQ^O^.lIifi. — Greei^ Vitriol. — This is the last in the series of salts made di- rectly from iron; it is obtained on the large scale by dissolving old scrap-iron in waste sulphuric acid, and puri- fying as far as possible by repeated crystallization. This form is usually employed for disinfecting and for other purposes which are not pharmaceutical. For pharma- ceutical purposes it should be made from the purest acid and iron wire. The following equation expresses the reac- tion: 2Fe, -f 2H,S0, = 2FeS0, + 2H,. Ferrous sulphate remains in solution, from which it is obtained by evapora- tion and crystallization. The salt occurs as large pale-green monoclinic prisms, efflorescing and becoming oxidized on exposure to air. It is odorless, has acid reaction, and is soluble in water but insoluble in alcohol. The crystals when heated melt in their water of crystallization. The impure salt, known in commerce as copperas, though it contains no copper, is used for disinfecting purposes. Granulated Ferrous Sulphate. Ferri Sulphas Granulatus. FeSO^.TH^O.— The crystals of sulphate of iron are dis- solved in water containing a little sulphuric acid and the solution poured into alcohol. The sulphate is insoluble in even dilute alcohol and precipitates in form of a granular powder; some of the impurities present in the crystals are soluble in alcohol, hence this method of precipitation yields conveniently not only a granular salt, but also a 256 PHARMACEUTICAL AND MEDICAL CHEMISTRY. very pure one. It is a pale-green powder less liable to oxidize in the air than the crystals and better adapted for dispensing purposes than the latter. Otherwise it is iden- tical with the crystals. Dried Ferrous Sulphate. Ferri Sulphas Exsiccatus. FeSO^.- H,0. — A convenient quantity of the powdered crystals of sulphate of iron is exposed to heat until it ceases to lose weight, ascertained by weighing at intervals of 30 to 40 minutes. This process yields a form of sulphate of iron containing only 1 molecule of water of crystallization, 6 being dispelled by the heat. It is a grayish-white powder and is used for making pills, or whenever the crystals are unfit for use on account of either their bulk or water of crystallization. The dried sulphate represents nearly twice as much anhydrous salts as the crystals do. Pills Aloes and Iron. Pi/ufcB Aloes et Ferri. — These pills contain each 1 grain of dried sulphate of iron and 1 grain of purified aloes, besides the excipients, aromatic powder and confection rose. Saccharated Ferrous Carbonate. Ferri Carbonas Saccharatus. FeOOg. — Sulphate of iron crystals are made to react upon sodium bicarbonate and the precipitate of ferrous car- bonate thoroughly washed. The drained precipitate is mixed with finely powdered sugar and the whole dried on a water-bath: FeSO, + 2NaHC03 = FeCOg + ]Sra,SO,+ CO, -|- HjO. Here again the sugar acts as a preserving agent, preventing the decomposition and oxidation of the car- bonate, which ordinarily is not stable. It is a grayish powder, odorless, partially soluble in water, and wholly soluble in hydrochloric acid with copious evolution of 00^ gas. If the precipitate is not thoroughly washed, traces of sulphate will remain. These can be detected by test solu- \ PHARMACEUTICAL AND MEDICAL CHEMISTRY. 257 tion of chloride of barium, which gives white precipitate in presence of sulphates. The carbonate is a ferruginous tonic; dose, 0.180 to 1.33 Gm. Mass of Ferrous Carbonate. Massa Ferri Carbonatis. FeCOg. — This preparation was formerly known as Pilula Ferri Carbonatis because it is usually employed in making pills, its consistence fitting it especially for that purpose. Sul- phate of iron and sodium carbonate react upon each other, thus: FeSO, + Na.COg = Na^SO, + FeCOg. The pre- cipitate is thoroughly washed and incorporated with sugar and honey to form a mass of a pilular consistence. Mass of carbonate of iron is popularly known as Vallefs Mass. Dose, 0.33 Gm. Reduced Iron. Ferrum Reductum. Fe^. — Subcarbonate or hydroxide of iron is heated or calcined until it is reduced to the oxide Fe^Og and this is then reduced to the metallic condition by passing hydrogen gas over it. The reactions Fe,(0H)3 + heat = Fe.Og + 3H,0, Fe.Og + 3H, = Fe, + 3H2O explain the process. It is a very fine black powder, wholly soluble in sul- phuric acid, and should contain not less than 80 per cent of metallic iron. It will burn in air, becoming the ferric oxide : 2Fe2 + 3O2 = 2Fe203, the chemical process being the same as rusting, only much more rapid and illustrative of the chemical affinity between the iron and the oxygen of the air. The finely divided iron exhibits a greater surface to the action of the oxygen, and the chemical action is conse- quently so intense as to produce heat and flame. Keduced iron is one of the most valued of the chalybeate tonics; it is given in doses of 0.120 to 0.330 Gm. in pill form. 258 PHARMACEUTICAL AND MEDICAL CHEMISTRY. Pills of Ferrous Iodide. PHuIcb Ferri lodidi. Fel^. — These pills are made by acting upon reduced iron with iodine, and adding to the filtered solution of the resulting iodide of iron, powdered sugar, licorice root, licorice extract and acacia, and evaporating the mixture until it attains a pilular consistence, when it is divided into pills. To prevent the iodine from becoming liberated and the iron from oxidizing, the Pharmacopaeia directs that the pills should be coated with tolu balsam, which is dissolved for the purpose in stronger ether. The pills are rolled in this solution and allowed to dry. The ether evaporates very quickly, leaving a thin, impervious and air-tight coating of balsam upon the pills. Compound Iron Mixture. Mistura Fern Composita. FeOO, + K^SO^. — Potassium carbonate is mixed with powdered myrrh, sugar, spirit of lavender to flavor, and rose- water, to which mixture, contained in a bottle in which the preparation is intended to be kept, coarsely powdered sulphate of iron is added, and the whole well shaken: FeSO, + K.COg = FeOOg + K^SO,. The mixture should be freshly prepared when wanted. It contains the sul- phate of potassium, which is formed, in addition to the carbonate, wherein it differs from the mass of carbonate of iron and the pills of iodide of iron, in each of which the formed sulphate is washed out and does not remain in the preparation. The mixture is similar in this respect to the compound pills of iron. It is also known as Griffith's Mixture. Pills of Carbonate of Iron. Pi/u/oe Ferri Carbonatis. FeOOg -|- K^SO^. — Potassium carbonate is rubbed with powdered myrrh and then with sulphate of iron, and when the reaction has ceased the mass is made into pills with PHARMACEUTICAL AND MEDICAL CHEMISTRY. 259 tragacanth, althaea, glycerin and water: FeSO^ -f Na^SO^ = FeCOg + Na^SO^. The reaction sometimes does not set in until the pills become softened in the stomach. Ferric Hypophosphite. Ferri Hypophosphis. Fq^{R^O^^. — Made by double decomposition between calcium hypo- phosphite and ferrous sulphate : FeSO^ + Ca(H2POj2 = Fe(H,POJ, (ferrous hypophosphite) + CaSO,. The calcium sulphate precipitates, while the ferrous hypophos- phite is held in solution. The application of heat during the evaporating of the solution changes the ferrous salt to the ferric condition. The ferric salt is a white or grayish powder, permanent in the air, odorless, nearly tasteless, and only slightly soluble in water. Ferric phosphate should be absent; if it is not, the salt is not completely soluble in acetic acid. Hypophosphite of iron was at one time highly recom- mended in the treatment of consumption, but its elBBciency was probably overestimated. It is now given as a blood and nerve tonic in pill or syrup form. Dose up to 0.66 Gm. Solution of Ferric Subsulphate. Liquor Ferri Subsulphatis. Fe,0(SO,),. — Solution" of Basic Ferric Sulphate, Mor- sel's Solutio:n'. — Sulphate of iron is added to a boiling mixture of sulphuric and nitric acids until effervescence ceases. The following equation approximately expresses the reaction: 12FeS0, + 3H,S0, + 4HNO3 = 3Fe,0(S0J, -f 5H2O + 2N2O2. The effervescence is due to the dis- engagement of the ^fi^ vapors, which, as soon as they are generated, unite with two atoms of oxygen, N^O^ + 0^ = ISTjO^, becoming the tetroxide of nitrogen, whose fumes, and not those of ^'2^2 ^ ^^^^ ^ reddish color. Enough dis- tilled water is added to adjust the percentage of metallic iron to 13.6. 260 PHARMACEUTICAL AN^D MEDICAL CHEMISTRY. MonseFs solution is a dark, reddish-brown, heavy liquid of a specific gravity of 1.55. It is nearly odorless, has a veiy astringent taste, and is miscible in all proportions with water and alcohol. Ferrous salt, which is sometimes present, is detected with test-solution of ferricyanide of potassium, with which it gives a deep blue color. This solution when diluted is the most valuable preparation for stopping bleed- ing or external hemorrhages. It is employed internally in doses of from 1 to 5 minims, well diluted. In some medical works, and among some physicians, the solution of suhsul- phate of iron is known as solution of persulphate of iron. Whenever the latter is prescribed the former should be dis- pensed, according to the U. S. Pharmacopoeia. Solution of Ferric Sulphate. Liquor Ferri Tersulphatis. Fe2(SOj3. — SoLUTioi^ OF Normal Ferric Sulphate. — The method for making this sokition is identical with that for the preparation of the preceding, except that the quan- tity of HjSO^ is increased sufficiently to convert all of the ferrous sulphate employed into the ferric condition: 12FeS0,+ 6H,S0,+ 4H]Sr03=:6Fe,(SOj3+ 8H,0+2N,0,. In comparing the equation expressing the reaction in the preparation of the solution of subsulphate of iron with that for the solution of tersulphate of iron, it will be seen that in the former 3 molecules of H^SO^ are employed, and in the latter 6, or just twice as many. This excess of H5SO4 in the latter over the former is just sufficient to convert the basic ferric sulphate into the normal ferric sulphate: 3Fe,0(S0,), -}- 3H.,S0, = 6Fe,(SOj3 + 3H,0. The strength of the solution in ferric sulphate is adjusted with distilled water to 28.7 per cent. Solution of tersul- phate of iron has nearly the same properties as the solu- tion of the subsulphate has, differing only in containing PHARMACEUTICAL AND MEDICAL CHEMISTRY. 261 more sulphuric acid and having a lower specific gravity — 1 .32. The solution of the subsulphate, when two volumes of it are slowly mixed with one volume of H^SO^ , deposits a white solid mass on standing, while the tersulphate solu- tion does not. This solution is used principally in the preparation of the third series of the iron preparations. Ferric Ammonium Sulphate. Ferri et Ammonii Sulphas. Fe2(NHj2(SOJ,.24H,0. — Ammonio Ferric Sulphate, Ammokia Ferric Alum, Iron Alum. — Made simply by dis- solving crystals of ammonium sulphate in solution tersul- phate of iron and allowing the double salt to crystallize. The salt is in form of pale, violet, eight-sided crystals, ef- florescent on exposure to air, sometimes melting in warm weather in its water of crystallization. It is odorless, styptic and soluble in water, insoluble in alcohol. In form of saturated or strong solution it is employed as a styptic. It is one of the alums. (See Alums.) Ferric Valerianate. FerH Valerianas. ^ejfj^^fi^^. — Solu- tion of tersulphate of iron is precipitated with a solution of sodium valerianate, the precipitated valerianate of iron collected, thoroughly washed and dried. It is a dark, tile-red, amorphous powder, having a faint odor of valerianic acid ; insoluble in water, soluble in alco- hol, and decomposed by boiling water, the valerianic acid being set free and ferric hydroxide remaining. The salt is very little used in pharmacy. Ferric Hydrate with Magnesia. Ferri Oxidum Hydratum cum Magnesia. Yq^{OH)^ -\- MgSO^. — Calcined magnesia is rubbed to a smooth and thin mixture with water and added to tersulphate of iron solution and the whole well shaken together. The preparation is official because it is antidotal to arsenous acid. It should be freshly prepared 262 PHAEMACEUTICAL AN^D MEDICAL CHEMISTRY. when wanted; the magnesia should be kept ready sus- pended in water, next to a bottle containing the prescribed amount of the diluted iron solution, so that the prepara- tion can be made at a moment's notice. When the two are mixed, the magnesia beiug in excess, ferric hydroxide and magnesium sulphate are produced: Fe2(SOj3 + 3MgO + 3H,0 = Fe,(OH), + MgSO,. The ferric hydroxide be- comes in a short time converted into the oxyhydrate, re,0,(OH),, by losing water, thus: Fe,(OH), - 2H,0 = 'Fefi^{0'K)^; a long exposure converts it finally into the ferric oxide, Fe^Og, by losing another molecule of water : Yefl^iOK)^ — H,0 = Fe^Og. In the proportion in which the ferric hydroxide loses water, it becomes worth- less as an antidote to arsenic, hence the great importance of making the antidote when needed. The ferric hydrox- ide becomes deoxidized by the arsenic and becomes the insoluble ferrous arsenate and ferrous hydroxide, according to this equation: 2Fe2(OH)g -|- ^s^Og (arsenous acid) = Fe3(As20 J2 (ferrous arsenate) + Fe(0H)2 (ferrous hydrox- ide) + SH^O. The sulphate of magnesium formed aids, through its cathartic action, to remove the insoluble arsenate of iron, but it is better to employ prompt emetics shortly after the administration of the antidote. Ferric Hydrate. Ferri Oxidum Hydratum. Yq^{0^)^. — Instead of using, as in the preceding, the oxide of magnesium, the hydroxide of ammonium is used as the precipitant in this preparation. It is, however, better to pour the solution of tersulphate of iron into the ammonia-water, which has been previously diluted: Fe,(S0j3 + e^^H^OH = Fe,(OH), + 3(XHJ2S0^. The whole is poured upon a wet muslin strainer and thoroughly washed with water. The product is the same as in the preceding, but without the presence PHAEMACEUTICAL AKD MEDICAL CHEMISTRY. 263 of any other salt, since the ammonium sulphate is washed out. The ferric hydroxide thus prepared is as efficient an antidote to arsenic as the above, the latter having the ad- vantage, though, of not being over-acid nor over-alkaline, the magnesia being very slightly alkaline and always in ex- cess. The XJ. S. P. directs that the ingredients for making ferric hydroxide should always be kept on hand, ready for immediate use. The hydroxide freshly prepared is a brownish-red magma gradually turning into the oxide Fe^Og upon exposure or upon drying. It is not used medicinally otherwise than stated; pharmaceutically it is of importance, inasmuch as from it the fourth series of iron preparations including the important scale salts are made. Troches of Iron. Trochisci Fern. Fe^O,. — These troches are made by massing dried hydroxide of iron with sugar, vanilla and mucilage of tragacanth, and cutting into con- venient forms, so that each troche contains 0.33 Gm. of the dried hydroxide of iron. Iron-Plaster. Emplastrum Ferri. — The ordinary strengthen- ing plaster contains dried hydroxide of iron incorporated with olive oil, Burgundy pitch and lead-plaster by means of gentle heat. Solution of Ferric Acetate. Liquor Ferri Acetatis. YQ^{(j^fi^^. — Ferric hydroxide, freshly prepared from solution tersul- phate of iron and ammonia-water and thoroughly washed, is dissolved in glacial acetic acid and enough water added to the solution to make it contain 31 pel* cent, of an hydroferric acetate: Fe,(0H)3 + 6HC,H30,=: Fe,(C,H30J, + 6H2O. The solution is a dark reddish-brown clear liquid with a pleasant acetous odor and sweetish taste ; specific gravity, 1.16. Ferrous salt may be present and may be found as usual with test-solution ferricyanide of potas- 264 PHAKMACEUTICAL AKD MEDICAL CHEMISTRY. sium. This preparation is used principally in the prep- aration of the official tincture. Tincture Acetate of Iron. Tin ctura Fern Acetatis. Fe^{CJIfi^)^ + O^H^OjHgOj. — Made from the solution of acetate of iron by diluting with alcohol and adding acetic ether, CjH^OjHgOj. This tincture is preferred by some physi- cians, especially by the German, to the tincture of chloride of iron. It decomposes in time, light and heat causing it to deposit a brown precipitate of probably an oxide. It should therefore be kept in a cool and dark place. Solution of Ferric Nitrate. Liquor Ferri Nitratis. ^^^{1^0^^. — Solution of ferric nitrate is obtained by dissolving freshly- prepared ferric hydroxide in nitric acid and adding enough water to make the solution contain six per cent of normal ferric nitrate. Thus prepared, solution of ferric nitrate is a transparent, reddish liquid having a strongly styptic taste and acid reaction; specific gravity, 1.05. Medicinally the preparation U an astringent tonic, and is given in doses up to 10 minims, 0.66 cc. Scale Salts. The class of compounds known as the Scale Salts of Iron is a series of iron preparations made by dissolving freshly precipitated ferric hydroxide in tartaric or citric acid or in their acid salts, and evaporating the solutions at a low heat until of a syrupy consistency, then spreading on plates of glass or porcelain, and allowing to dry thereon until the compounds separate in scales. The secondary products re- main and form part of the compounds, which become, according to the acid or acid salt used, potass io-citrate of iron or potassio-tartrate of iron, or similar ammonium or sodium compounds of iron. They are of varying chemical PHARMACEUTICAL AND MEDICAL CHEMISTRY. 265 constitution^ and the formulas and equations following are probably only approximate, yet they aid to illustrate the composition of the compounds. The separate processes of the official scale salts are described below. Iron and Potassium Tartrate. Ferri et Potassii Tartras, — Potassio-Ferric Tartrate. — Probably Fe2Ke(C,H40 J^. To some fresh ferric hydroxide a quantity of acid potassium tartrate is added, and after solution has been effected by means of a water bath, in which the temperature does not rise above 140° F. (or 60° C), the whole is filtered and evapo- rated to a syrupy consistency, and poured on glass plates to dry and scale. The addition of a little ammonia during evaporation prevents the formation of a precipitate after solution. The reaction may be according to the equation Pe,(OH). + 6KHC,H.O. = Fe,K,(C.H.O.). + 6H,0. This and the succeeding compound have a chemical similarity to Eochelle salt, the double tartrate of sodium and potas- sium — KNaO^H^Og. In the former the hydrogen of the acid tartrate of potassium has been replaced by ferric iron, Fe^, and in the latter by sodium. The normal tartrate of iron is only very slightly soluble. This compound is in transparent garnet-red scales, odor- less, sweetish, soluble in water but not in alcohol, and is used as a mild iron tonic in doses up to 1.00 G-m. Iron and Ammonium Tartrate. Ferri et Ammonii Tartras. — Am- monio-Ferric Tartrate. — Probably Fe2(NHJg(04H40e)„. Prepared as the above, substituting acid tartrate of ammonium for the potassium salt. It possesses the same properties as the preceding salt does, only being sometimes of a yellowish-brown color. The acid ammonium salt is made as part of the process by adding carbonate of ammo- 266 PHAEMACEUTICAL AKD MEDICAL CHEMISTRY. nium to tartaric acid in molecular proportions: (NHJ^COg + 2H,C,H,0, = 2NH,HC,H,0, + CO, + H,0. Solution of Ferric Citrate. Liquor Ferri Cifrat/s. ¥e^{C^'Kfl^)^. — Ferric hydroxide is dissolved in citric acid and the solution adjusted to a strength of 35.5 per cent with water. Pe,(OH), + 2H,C.HA = Fe,(C.H.O,), + 6H,0. It is a dark-brown liquid, odorless, and has a ferruginous taste; specific gravity, 1.25. Owing to the fact that it is just half the strength of the scales, the pharmacist will find it very convenient to use when the citrate is prescribed in aqueous solution. Soluble Ferric Phosphate. Ferri Phosphas So/ubHis, — Phos- phate of sodium is dissolved in a solution of ferric citrate and the solution scaled. 1'he scales are a sodio-ferric-citro- phosphate. This, like the other scale salts, is not a definite compound, and its formula can only be given approximately. This scale compound contains Na^HPO^ and re2(C6H50,)2 in a state of combination. It is in bright-green scales, odor- less, very soluble in water and insoluble in alcohol. Its advantage over the normal phosphate is in its solubility. Dose up to 0.66 Gm. Syrup of the Phosphates of Iron, Quinine and Strych- nine. Syrupus Ferri, Quininas et Strychninae Phosphatum. — Quinine sulphate and strychnine are dissolved in solution of phos- phate of iron containing an excess of phosphoric acid, and sugar and distilled water added to make a syrup. The ex- cess of phosphoric acid dissolves the alkaloids, converting them into phosphates. The syrup contains .02 per cent. of strychnine alkaloid and 3.00 per cent of quinine sulphate. Soluble Ferric Pyrophosphate. Ferri Pyrophosphas Solubilis. — Ferric Pyrophosphate. Made as the preceding, employ- PHARMACEUTICAL AI^D MEDICAL CHEMISTRY. 267 ing the pyrophosphate in place of the phosphate of sodium. It occurs in thin green, transparent scales, and is very freely soluble in water, on account of which it is frequently em- ployed in solution. Dose up to 5 grains, 0.33 gm. Ferric Citrate. Ferri Citras. Fe^{C^'Efi^)^.—The scales of citrate of iron are obtained by simply evaporating the solu- tion of citrate of iron. They are of a garnet-red color, are odorless, and slowly but wholly soluble in water and insolu- ble in alcohol. Because the salt is very slowly soluble it is not so frequently used as the succeeding one. Dose up to 1.33 Gm. Iron and Ammonium Citrate. Ferri et Ammonii Citras. — Am- MOifio-FERRic Citrate. Made, as the above, by the addition of a little water of ammonia to the solution of citrate of iron before evaporating. The addition of ammonia fur- nishes a salt which is more soluble than the above but otherwise identical with it. Wine of Ferric Citrate, l^inum Ferri Cifratis. — An agreeable chalybeate tonic prepared by dissolving citrate of iron and ammonium in white wine and adding syrup and tinc- ture sweet orange-peel to flavor. It contains 4 per cent of citrate of iron and ammonium. Dose, up to 4 cc. Some- times called sweet iviiie of iron. Bitter Wine of Iron. Vinum Ferri Amarum. — Made by dis- solving soluble iron and quinine citrate in white wine and adding tincture of sweet orange-peel and syrup. It con- tains 5 per cent, of the scale salt. Iron and Strychnine Citrate. Ferri et Strychnince Citras. — Strychnine is dissolved in a solution of citrate of iron and ammonium containing citric acid, and the solution evapo- rated and scaled. Thus obtained the. compound is in form of transparent garnet-red scales, deliquescent on exposure 268 PHAEMACBUTICAL AN^D MEDICAL CHEMISTRY. to air, odorless, bitter taste, wholly soluble in water and only slightly soluble in alcohol. It contains one per cent of strychnine. Dose up to 0.20 Gm. Soluble Iron and duinine Citrate. Ferri et QuinincB Citras Solubilis. — Quinine and citric acid are dissolved in solution of citrate of iron, and the whole evaporated and scaled. It forms thin, transparent scales of a greenish, golden-yellow color. Slowly deliquescent upon exposure to the air, odor- less, bitter taste, very soluble in water and but slightly solu- ble in alcohol. It should contain 12 per cent, of quinine, but very often it is found in the market with a deficiency of quinine. The Manganese Salts. The salts of manganese are not of much importance in pharmacy and medicine; there are only two official, the dioxide and the sulphate. Manganese is found in nature mainly as the dioxide, MnOj , called pyrolusite or braun- stein ; the Mn^Og and MngO^ and the carbonate also occur in nature. Manganese is present in the radical of potassium per- manganate. Manganese Dioxide. Mangani Dioxidum. MnO,. — Black Oxide of Manganese. — The U. S. Pharmacopoeia recognizes the native crude product, which contains at least QQ per cent of the pure dioxide. It is a heavy, grayish-black gritty powder, odorless, tasteless, and permanent in the air, insoluble. Its chief use is in the preparation of oxygen; when heated it gives off oxygen, becoming the Mn30, - 3MnO, + heat = Mn30, + 0,. Manganese Sulphate. Mangani Sulphas. MnSO^ + ^^fl. — When the dioxide is digested with concentrated sulphuric PHARMACEUTICAL AN^D MEDICAL CHEMISTRY. 269 acid the sulphate is formed with the liberation of oxygen : 2MnO, + 2H,S0, = 2MnS0, + 2H,0 + 0,. This salt occurs in colorless or pale rose-colored transparent prisms which are somewhat efflorescent in dry air, very soluble and of a bitter and astringent taste. The aqueous solution of the salt yields with ammonium- sulphide test-solution a flesh-colored precipitate, soluble in dilute acids. If a little of the dry salt is mixed with a little sodium hydroxide and the mixture fused, it will yield a dark green mass which dissolves in water with a green color. The Arsenic Salts. Occurrence. — The element arsenic is sometimes found in a native state, but the largest proportion is derived from the sulphides, realgar, As^S^, and orpiment, As^Sg, and from the arsenical iron ores, the latter consisting chiefly of FeASg, NiASj and CoAs^. Mispickel, Fc^S^As, is also a source, and arsenous acid, As^Og , is found in nature as the mineral arsenolite. There are many other forms of occur- rence, but they are not utilized much as sources of the element. Preparation. — The ores, preferably the arsenical iron ores, are roasted in a reverberatory furnace and the volatile product, crude arsenous oxide, As^Og , condensed in long and nearly horizontal chimneys, or in a series of chambers made of brick. The arsenic volatilizes and unites with oxygen, becoming the arsenous oxide, As^ + 30, = 2AS2O3 , which condenses and forms the crude oxide which is puri- fied by resublimation. The purified As^Og is then heated in retorts with charcoal, which unites with the oxygen. 270 PHARMACEUTICAL AN^D MEDICAL CHEMISTRY. leaving the arsenic in the elementary state as a sublimate : 2As,03 + 3C, = As, + 600 (or 3C0J. Properties, Physical and Chemical. — Arsenic is a steel- gray, crystalline solid, having a lustre, and a specific gravity ranging from 5.70 to 5.95. It is brittle, tarnishes in air but not in pure water, for which reason it is often kept in distilled water. When heated it volatilizes, but heated in air it becomes oxidized and sublimes as As^Og. It is both triad and pentad, more often the former ; its atomic weight is 75 (exactly 74.9) and its vapor density (compared to hydrogen) 149.8, which is twice its atomic weight, so that its molecule in the gaseous state occupies only half as much space as the molecule of hydrogen does. Arsenic is therefore, like phosphorus, an exception to the rule that the atomic weights of elements under similar conditions give equal volumes of vapor, or, in other words, that the vapor density of an element is half its molecular weight, a molecule being supposed to consist of two atoms. It appears from this that the molecule of arsenic consists of four atoms. As,. Arsenic also, like iron, mercury and some of the other metals, forms two series of compounds the ShYsenous and the arsenic, exemplified in the oxides ASjOg , arsenous, and As^O^ , arsenic. In the former it has 3 bonds, in the latter 5 : a4 As,0, = >0 As^ \0 As,0, - / As=0 ^0 Arsenic is considered by some chemists as being a non- PHARMACEUTICAL AND MEDICAL CHEMISTRY. 271 metal, but the majority class it as a metalloid {oid means like) because its chemical behavior is similar to that of the metals in many respects. It behaves in the dual capacity, chemically, of a non-metal and of a metal. In the former it resembles phosphorus, uniting, e.g., with oxygen to form oxides, which oxides with water produce the corresponding acids, from which corresponding salts may be prepared. The following will illustrate : Oxides As,03 + 3H2O ArsenoMS Oxide. Water. AS2O5 + 3H2O Arsenic Oxide. Acids 2H3ASO5 3H2 + 3Ks 2K3ASO: Arsenotts Acid. Replacing H by K. Arsenate of Potassium. 2H3ASO4 -3H2 + 3K2 Arsenic Acid. Replacing H by K. Salts 2K3ASO4 Arsenafe of Potass Oxides P2O3 + 3H2O PhosphoroMS Oxide. P2O5 + 3H2O Phosphoric Oxide. Acids 2H3PO3 Phosphorows Acid. 2H3PO4 Phosphoric Acid. - 3H2 + 3K2 Replacing H by K. -SHa + 3K2 Replacing H by K. Salts 2K3PO3 Phosphide of Potassium, 2K3PO4 Phosphate of Potassium. The above are all normal or ortho-compounds. A further similarity between phosphorus and arsenic will be seen in the following comparison of their meta- and pyro-com- pounds : Oxides AS2O3 ASjOg + HaO_ +H.,0 Acids 2HASO2 Metarsenous Acid. 2HASO3 Metaarsenic Acid. — H2 -r K2 — Hg -|- K2 Salts 2KASO2 Metarsenite of Potas- KAsOs Metarsenate of Potas- sium, (Fowler's Solution.) sium. Oxides P2O3 P2O5 + H2O +H2O Acids 2HPO2 Metaphosphorous Acid. 2HPO3 Metaphosphoric Acid. — H2 -\- K2 — H2 -j- K2 Salts 2KPO2 Metaphosphite of Potas- KPO3 Metaphosphate of Potas- sium, sium. 272 PHABMACEUTICAL AKD MEDICAL CHEMISTEY. In a like manner the pyroacids and pyrosalts may be obtained by adding two molecules of water to each of the oxides of arsenic and phosphorus. Any other metal may be employed to replace the potassium, if in equivalent proportions. As^Og As^O, + 2H,0 +2H,0 H^ASjOj, Pyroarsenous acid. H^As^O^, Pyroarsenic acid. The salts ortho-, pyro-, and meta-arsenites and arsenates are therefore obtained, in theory, by replacing the hydro- gen in the acids as above shown — the arsenic in them behaves as a non-metal, resembling phosphorus. In the other capacity arsenic acts as a metal; that is, it occupies the base in a number of salts, in such as AsClg, AsBrg, As^Sg, etc. (See Antimony.) Important Analytical Reactions. — 1. Hydrogen Sul- phide produces in acid solutions precipitate of the yellow sulphide, As.Og + 3H,0 + 3H,S = As.Sg + 6 H,0. 2. Arsenic Salts are soluble in ammonium sulphide: As,S3 -f 3(]SrHJ,S - 2(NHj3As,S3. 3. Marsh's Test consists in reducing arsenic com- pounds to metallic arsenic by means of nascent hydrogen. With the latter arsenic enters into combination to form arsenous hydride or arsenuretted hydrogen, which is iden- tified by numerous reactions, but usually by its behavior when passed into silver nitrate solution, or when ignited and its flame directed upon cold porcelain. The hydrogen is usually generated from H^SO^ by means of zinc: 2H2SO4 -|- Zn2= 2ZnS0^+ 2^^. The H in contact with arseuic becomes ASH3 thus : As.Og -f 6H, = 2H3AS + 3H,0. The HgAs is a very poisonous gas, and care should be had not to inhale PHARMACEUTICAL AI^D MEDICAL CHEMISTRY. 273 it. It burns with a yellow flame, producing As^Og thus: 2H3AS + 30, = 3H,0 + As fi^. If the flame be directed against cold porcelain or glass, the reduction of temperature prevents the oxidation of the arsenic, and it deposits in black or steel-gray spots: 4H3AS -f- 30^ = QB.fi + As^. Anti- monure'tted hydrogen produces similar spots under simi- lar conditions. (See Antimony), The arsenic spots are dissolved by a solution of hypo- chlorite of sodium: As, + lONaOlO + 6B.fi = 4H3ASO, + lONaCl. (Difference from antimony spots, which remain unaffected.) If the HjAs is passed into solution of silver nitrate, the silver is reduced to metallic condition and precipitates: H3AS + 6AgN03 + 3H,0 = 3Ag, + H3ASO3 + 6HNO3. This test is usually employed to distinguish arsenic from antimony — the antimony precipitates, the arsenic does not. 4. Fleitman^s Test consists in generating hydrogen from metallic zinc or aluminum and strong solution of soda or potassa by heating. The addition of the solution of an arsenic salt will produce arsenuretted hydrogen, which may be tested as above: 2k\ + 4K0H + As.Og + H,0 = 2H3AS + 2K,A1,04. The value of this method is that it does not produce antimonuretted hydrogen, affording a ready means of distinguishing between arsenic and anti- mony salts. 5. Reinsch's Test is applied by adding a piece of bright copper to an (HOI) acidulated solution of an arsenic salt and boiling. If arsenic is present, the copper will become coated with a deposition of metallic arsenic. It is essential that the copper be chemically pure. 6. Berzelius' Test. When the arsenic oxides are heated in a long test-tube with charcoal, the arsenic becomes re- 274 PHARMACEUTICAL AKD MEDICAL CHEMISTEY. duced to the metallic condition and deposits on the inside of the tube as an iron-gray mirror. Arsenic in state of vapor has a garlicky odor, which may be noticed in the carrying out of this test. The vapor is poisonous. 4AS2O3 + 30, = 2As,+ 600,. 7. Ammoniacal Solutions' of Oopper Sulphate gives a grass-green precipitate in solutions of arsenic. The preci- pitate dissolves in XH^OH. It consists of OUgASgOg-SH^O (or 3OuO.AS2O3.2H2O) and is known as Scheele's green. 8. Ammonio-Nitrate of Silver Solution produces a lemon-yellow precipitate of arsenite of silver in solutions of arsenic, which dissolves in an excess of ammonia. (Am- monio-nitrate of silver solution is prepared by adding NH^OH to AgNOg until the precipitate at first produced is nearly all dissolved.) 6NH,0H + BAgNOg + 2As,03 = 2Ag3As03 + 6NH,N03 + 3H,0. Arsenous Oxide. Acidum Arsenosum. As^Og. — White Arse- nic. — This compound is popularly known as arsenic and as arsenous acid. Both terms are incorrect, but they have been so thoroughly established by usage that the Pharmaco- poeia has not -discarded their use. Arsenous acid consists, as shown above, of H3ASO3; all acids contain hydrogen. The As^Oa is obtained, as above shown, in the preparation of metallic arsenic. From it all other pharmacopoeial compounds are made. It is a heavy, white, opaque powder or semi-transparent mass, perma- nent in the air, volatile when heated, odorless, tasteless, slowly soluble in water, freely in HCl and in the alkaline hydroxides and carbonates. Its strength of purity should be at least 98.80 per cent. Arsenous acid is very poisonous and is often bought with suicidal intention; the careful pharmacist will only dispense PHARMACEUTICAL AND MEDICAL CHEMISTEY. 275 it upon physicians^ orders. Its antidote, as for all arsenic compounds, is freshly precipitated ferric hydroxide (see Ferric Hydroxide), which forms an insoluble, and hence harmless, salt with it: 2Fe,(0H), + As,03 = Fe3(AsOJ, (ferrous arsenate) + Fe(0H)5 (ferrous hydroxide) + SH^O. The oxide is given in doses up to 0.003 Gm. Medici- nally it is an alterative. Solution of Arsenous Acid. Liquor Acidi Arsenosi. H3ASO3. — This preparation is a solution of the oxide As^Og in water, the solution being aided by heat and the addition of a small quantity of hydrochloric acid. The latter does not enter into combination with the oxide; it merely facilitates solution. The solution is a convenient means for the administra- tion of arsenic in liquid form, but it is less popular with physicians than the following. Dose is up to 5 minims, 0.33 cc. It contains 1 per cent of As^Og. Solution of Potassium Arsenite. Liquor PotassH Arsenitis. KAsOj. — This solution, popularly known as Fowler's Soke- Hon, is prepared by boiling together arsenous acid and potassium bicarbonate until solution ensues, flavoring with compound tincture of lavender, and filtering after a week: As,03 + 2KHOO3 = 2KAsO, + 2C0, + H,0. Chemists are not certain whether the two salts react upon each other, and if they do, whether the orthoarsenite, K3ASO3 (or KH^AsOg), or the metarsenite, KAsO^, is formed. It is probable, though, that the latter is formed. The solution contains 1 per cent. As^Og. It is an agreeable preparation and is used more extensively than any other form of arsenic. Dose is up to 5 minims, diluted. It should never be kept longer than a year, as after that time and often before, it begins to deposit the arsenous oxide. 276 PHAEMACEUTICAL AND MEDICAL CHEMISTRY. becoming proportionately weaker, and creating the possi- bility of poisoning by the careless administration of the deposit. The solution should never be dispensed unless it is perfectly clear and transparent. Arsenic Iodide. Arseni lodidum. Aslg. — The iodide is made by directly combining iodine with arsenic, the union being facilitated by dissolving the iodine in disulphide of cai-bon and adding the arsenic in powder until the purple color of the iodine disappears, carefully evaporating and crystalliz- ing: As^ -|- 6I2 = 4ASI3. The arsenic iodide thus pre- pared is in shining, orange-red crystalline scales losing iodine upon exposure to air; volatile, soluble in water and alcohol, gradually decomposing in solution. This com- pound is rarely used by itself, but is usually combined with iodide of mercury in the preparation of Donovan's Solution. Solution of Arsenic and Mercuric Iodide. Liquor Arseni ef Hydrargyri lodidi. AsIg.Hglg. — One per cent of each of the iodides of arsenic (arsenic) and mercury (mercuric) are dissolved in water and the solution filtered. Probably no chemical reaction takes place. The solution should be of a light straw-color; any deeper color is due to the pres- ence of disengaged iodine, and may be removed by the addition of a globule of mercury, or of a few grains of metallic arsenic, and filtering. This solution, like the other arsenic and mercury preparations, is an alterative. Dose, up to 5 minims, diluted. Sodium Arsenate. Sodii Arsenas. ]Sra2HAsO,.7H20.— See Sodium Salts. Solution of Sodium Arsenate. Liquor Sodii Arsenatis.—A preparation containing one per cent of sodium arsenate dissolved in distilled water. Paris Green. — This unofficial arsenic compound is an PHAEMACEUTICAL AND MEDICAL CHEMISTRY. 277 ciceto-arsenite of copper prepared by boiling solution of arsenous acid with solution of acetate of copper. It is of variable composition and may be any of the following: 3(CuO.As,03).Cu(0,H30,),; 3(CuO.As,03).2Cu(C,H30J,; 5(CuO.As,03).2Cu(0,H30,), + 2H,0; 5(CuO.As;03).20u(0,H30J, + 5H,0. The last is considered to be the best. It is often termed Vienna or Imperial Green. It should be sold with caution, being exceedingly poisonous. Antimony Salts. Occurrence. — Antimony occurs with arsenic chiefly as a sulphide, SbgSg, and also native. The former when freed from earthy impurities by fusion constitutes the crude or hlack antimony of the market. Preparation. — The metal may be obtained from its ores by heating them with carbonates of potassium or so- dium, or with metallic iron, which retains the sulphur, or by roasting and heating with charcoal. The latter is the method usually employed. 2Sb2S3 -|- heat -}- QO^ = 2Sb,03 + 6S0„ 2Sb,03 + 20, = 2Sb, + 200, + 200 (00, + 00 in variable proportions). The metal is not used in pharmacy; the purified sul- phide furnishes directly or indirectly all of the preparations of the Pharmacopoeia. Metallic antimony has numerous ap- plications in the arts; type-metal, pewter, etc., are alloys containing it. Properties. — Antimony is a bluish-white metal, lustrous, very brittle, and hence easily pulverized; specific gravity, 6.8; volatile at high heat. 278 PHARMACEUTICAL AKD MEDICAL CHEMISTRY. It does not oxidize in the air at ordinary temperatures, but when strongly heated it burns, producing the oxide SbjOg. Dissolved in nitric acid it is oxidized to antimonic acid ; hydrochloric acid dissolves it, forming a chloride, SbClg, and free hydrogen. Antimony has chemical proper- ties very similar to those of arsenic ; it forms two classes of compounds — the antimonous and antimonic. In the former it is trivalent, SbClg, Sb^Sg, Sb^Og, in the latter quinquivalent, Sb^O^, SbCl^, Sb^S^. Graphically, antimonous compounds may be thus ex- pressed : SbCl3: S\0,: /CI ^h^O \oi Vo Antimonic thus, SbCl,: Sb^O,: /Cl ^0 y>Cl Sb=0 Sb^— CI >0 \>C1 Sb=0 \C1 ^0 The atomic weight of antimony is 120; its molecule con- sists of two atoms, Sb^. Nearly all that has been said of the chemical behavior of arsenic is also true of antimony. Antimony forms the base in some compounds, SbClg, and the radical in others, NaSbO^ sodium antimonite. The trioxide Sb^Og unites with watfer to form antimon- ons acid, Sb,03 + H,0 = 2HSbO, , which forms salts called antimonzYes by having its hydrogen replaced by a metal, e.g. KSb^O, antimonite of potassium. PHARMACEUTICAL A^D MEDICAL CHEMISTRY. 279 The pentoxide produces the antimouic acid with water, SbjOg + HjO = 2HSb03 , from which antimona^e^ are ob- tained. Both tliese acids are monobasic. The Sb^O^ yields also a dibasic acid with H^O, thus: Sb^O^ + 2B.^0i = H.Sb,0,. Important Reactions (see also Arsenic). — 1. H^Sin acidi- fied solutions of antimony salts gives orange-red precipitate. 2. Ai^TiMON"Y Salts dissolve in (NHJ^jS^: 2Sb2S3 + 6(NHJ,S, = 4(NHj3SbS, + S,. 3. Marshes Test, employed as for arsenic, yields anti- monuretted hydrogen, H3Sb: Sb,03 + 6H, == 2H3Sb + SH^O. The HgSb ignited and its flame directed upon cold porcelain produces black spots by the deposition of metallic antimony. These spots remain unaffected with solu- tions of hypochlorites (arsenic spots dissolve and disappear). If HgSb is passed into silver nitrate solution, the anti- mony is precipitated (Arsenic remains in solution) : HgSb + 3AgN03 = Ag3Sb + 3HNO3. 4. Aktimoi^y is precipitated from its solution as black powder by iron or zinc; copper removes it from solution in form of metallic film. 5. A CON'CEKTRATED SOLUTIOlSr OF THE OhLORIDE poured into water produces a precipitate of the oxychlo- ride: SbCl3 + H,0 = SbOCl + 2HC1. Antimony Sulphide. Antimonii Sulphidum. Sb^Sg. — The crude ores are fused in such a way that most of the earthy im- purities are removed. When cold the sulphide is in steel- gray masses of metallic lustre, or in black lustreless pow- der, odorless, insoluble, tasteless. The TJ. S. P. directs it to be "as free from arsenic as possible." It is used mainly to prepare the purified sulphide in pharmacy, and as an alterative in veterinary practice. 280 . PHARMACEUTICAL AND MEDICAL CHEMISTRY. Purified Antimony Sulpliide. Antjmonii Sulphidum Purifhatum. SbjSg. — The above-described sulphide, finely powdered, is macerated for several days witli ammonia- water, thor- oughly washed and dried. The ammonia-water dissolves the sulphide of arsenic, which is associated with the anti- mony in the ores, leaving the antimony sulphide as residue (see Second Eeaction of Arsenic Salts). The sulphide thus purified is a dark-gray powder, odor- less, tasteless, insoluble in water, soluble in hot hydro- chloric acid with the evolution of H^S gas. It should not contain more than mere traces of arsenic. The orange-red precipitate obtained by passing H^S gas into solutions of antimony has the same composition, Sb^Sg. It is changed to the black variety by heating. It is not used internally, but enters into the preparation of the Sulphurated Antimony. Sulphurated Antimony. Antimonium Sulphuratum. Sb^Sg.- Sb^Og. — This preparation, sometimes called Kermes Min- eral, is obtained by boiling the purified antimony sulphide with soda solution and adding sulphuric acid : GNaOH + Sb^Sg = NagSbOg (sodium antimonite) + NagSbSg (so- dium sulph-antimonite) -{- SH^O. To the hot solution of the latter two compounds H^SO^ is added which precipi- tates the sulphide and oxide : 2]^a3Sb03 + SlSTagSbSg + 6H,S0, = 6Na,S0, + Sb.Sg + ^\0, + 3H,S + 3H,0. The precipitate, consisting almost wholly of the Sb^Sj , is thoroughly washed to remove the sodium sulphate which remained in solution and dried. It is a reddish- brown amorphous powder, odorless, tasteless, insoluble. It should be free from sulphate, ascertained with Bad,. (There are many varieties of sulphurated antimony ; the above is the official one.) PHARMACEUTICAL AND MEDICAL CHEMISTRY. 281 It is emetic and alterative in doses up to 0.330 Gm. Usually given in pill form. Compound Pills of Antimony. PHulae Antimonii Compositae, Plummer's Pills. — Pills containing each 0.040 Gm. of sul- phurated antimony, 0.040 Gm. of calomel and 0.080 Gm. of guaiac made into mass with mucilage of tragacanth. No chemical reaction takes place between the ingredients. Given in skin diseases. Antimony Oxide. Antimonii Oxidum. Sb^Og. — Obtained by dissolving ^^^^^ in hydrochloric acid, pouring the solution into much water and treating the resulting precipitate with ammonia-water : Sb^Sg -f 6HC1 — 2SbCl3 (antimonous chloride) + 3H,S. 10SbOl3 + 15H,0 = 5Sb,03 (antimon- ous oxide) + 30 HCl. Not all of the SbOlg is converted into the oxide, but some becomes the oxychloride, SbClO : 2SbOl3 + 2H,0 = 2Sb010 + 4HC1. The SbClO is con- verted into the oxide by having its chlorine removed with NH^H : 2SbC10 + 2NH3 + H.^0 = ^\0, + 2NH,C1. Oxide of antimony is a whitish powder, permanent in the air, odorless, tasteless, almost insoluble in water, insoluble in alcohol, soluble in hydrochloric or nitric or tartaric acids. It should be free from arsenic, chloride and sulphate. It enters into the preparation of antimonial powder and tartar emetic. Antimonial Powder. Pulvis Antimonia/is. Sb^Og + 0a3(P0j2. — A powder consisting of 33 per cent oxide of antimony and 67 per cent precipitated phosphate of calcium, and given as a diaphoretic in doses of 0.20 to 0.330 Gm. Antimony and Potassium Tartrate. Antimonii et Potassii Tartras, 2KSbOC,H,0,.H,0, Tartar Emetic— Made by boiling together antimony oxide and potassium bitartrate and allowing the solution to crystallize : 2^.110 Jlfl^ -\- 282 PHARMACEUTICAL AND MEDICAL CHEMISTRY. Shfl, = 2KSbOC,H,0, + H,0. The hydrogen in the base of the acid tartrate of potassium is replaced by SbO. Tartar emetic is in form of granular powder or as small transparent crystals, of a sweetish taste, soluble in water, in- soluble in alcohol. It should be free from arsenic. This is the most important of the antimony compounds, being used extensiyely, as its name indicates, as an emetic. All the antimonial preparations have more or less emetic properties, a fact which accounts for the absence of cases of poisoning by antimony. The antidote would be tannin, w^hich produces the insoluble tanuate of antimony. Wine of Antimony. I^inum Antimonii. KSbOO^H^Oe. — A preparation made by dissolving 4 parts of tartar emetic in 1000 parts white wiue containing 150 parts of alcohol. It is usually added to expectorant mixtures. Dose, 5 to 10 minims. Bismuth Salts. Occurrence. — Bismuth occurs in the metallic state, and often as sulphide associated with traces or more of arsenic. Properties. — Bismuth is a grayish-white metal with a pinkish tint; it is crystalline, brittle, brilliant; specific gravity 9.8, and has some resemblance to metallic anti- mony. Chemically it is closely allied to antimony. It is usually trivalent, sometimes quinquivalent; atomic weight 208.9. There are only four of its compounds ofl&cial, and beyond the employment in medicine it is little used. Analytical Reactions. — 1. Water precipitates from acidu- lated bismuth solution white basic salts which contain more or less of the acid radical in proportion as little or much water is used: BiClg + H,0 = BiOCl + 2HC1 (see Antimony). PHARMACEUTICAL AKD MEDICAL CHEMISTRY. 283 2. Alkaline Hydroxides precipitate bismuth hy- droxide: BiClg + 3K0H = Bi(0H)3 + 3KC1. 3. Hydrosulphuric Acid aj^td Sulphides produce black precipitate of Bi^Sg which is insoluble in alkali sul- phides, affording a means of separating bismuth from ar- senic and antimony: 2BiCl3 + 3H,S = Bi.Sg + 6HC1. Bismuth Subnitrate. Bismuthi Subnitras. BiONOg.H^O. — Prepared in a necessarily circumstantial way by dissolving bismuth in diluted nitric acid, diluting the resulting solu- tion with a prescribed quantity of water, and allowing to stand for a day, then filtering. The filtered solution is then poured into a solution of sodium carbonate during constant stirring, the precipitate drained and washed and dissolved in nitric acid. The nitric-acid solution is again allowed to stand for a day, then again diluted with a pre- scribed quantity of water, and some water of ammonia added, and the precipitate thoroughly washed and dried. Metallic bismuth as a rule contains arsenic, and in the above process provision is made for its separation. The rationale of the process is as follows : The bismuth dis- solves to bismuth nitrate in nitric acid, and some of the arsenic becomes arsenic acid: Bi^ + 8HNO3 = 2Bi(N03)3 bismuth nitrate (normal), + N,0,+4H,0, 3As,+20HNO3 + 8H,0 = I2H3ASO,, arsenic acid, + lON^O,. The bismuth nitrate and the arsenic acid react upon each other, producing bismuth arsenate, Bi(N03)3 + H3ASO4 = BiAsO^ + 3HNO3. Both of these salts when their solu- tion is diluted with water begin to separate and deposit, but the arsenate needs less water to cause it to separate than the nitrate does, and hence just enough water is added to the solution to cause the arsenate, but not the nitrate, to deposit. "When the arsenate has deposited, after a day^s 284 PHARMACEUTICAL A^D MEDICAL CHEMISTRY. standing, it is removed by filtration. Any arsenate which may not have deposited when the sodium carbonate is added becomes the very soluble arsenate of sodium, which remains in solution while the bismuth is precipitated as the insoluble subcarbonate : Na^COg + HgAsO^ = Na^HAsO^, arsenate of sodium, + H,0 + CO,. SNa.COg + 261(^03)3 = Bi,0,003, subcarbonate bismuth, -f GNaNOg + 2C0,. The subcarbonate is washed and the arsenate of sodium removed in the washings. As a further precaution to in- sure the entire absence of arsenic, the subcarbonate is again dissolved in nitric acid, and the solution again diluted to a point at which any arsenic still present will precipitate according to above equation. After some time the normal nitrate is converted into the subnitrate or oxynitrate by further dilution with water and the neutralization of the nitric acid present with ammonia water: Bi(N03)3 + H,0 = BiON03 + 2HNO3, HNO3 + NH.OH = NH,N03 + H,0. The subnitrate of bismuth thus prepared is a heavy white powder permanent in the air, odorless, almost tasteless and insoluble. It should be free from carbonate : effervescence with acids would indi- cate its presence. Subnitrate of bismuth is largely used in stomach troubles as sedative and tonic. Dose up to 0.66 Gm. Bismuth Subcarbonate. Bismuth/' Subcarbonas. Bi202C03.- H2O. — The subcarbonate is made as above shown in the making of the subnitrate. (See the preceding for equa- tions and rationale.) It is a pale yellowish-white powder, permanent in the air, odorless, tasteless and insoluble. It may contain more impurities than the subnitrate because in the latter the process of purification is further carried on, especially in PHARMACEUTICAL AND MEDICAL CHEMISTRY. 285 the elimination of arsenic. The impurities which may be present are insoluble foreign salts, alkalies and alkaline earths, lead, copper, chloride and sulphate, and traces of arsenic and antimony. Its use is similar to that of the subnitrate, and the dose the same. Bismuth Citrate. Bismuth! Citras. BiCgH^O,. — This salt is prepared by boiling bismuth subnitrate with citric acid and water for 15 or 20 minutes, or until a drop of the mixture dissolves in ammonia-water. Then the suspended matter is allowed to subside, the solution decanted and the deposit washed with water on a filter until the washings are tasteless. Thus obtained it is usually an amorphous powder without taste or odor and insoluble in water, but soluble in ammonia-water and in solutions of the citrates of the alkalies. It is official mainly for its employment in the bismuth and ammonium citrate. Incomplete wash- ing in its preparation usually results in the presence of nitrate in the salt. The usual test for nitrates should be applied. Bismuth and Ammonium Citrate. Bismuth! et Ammoni! Citras. — The introduction of this salt into medicine was mainly to obtain a soluble salt of bismuth. It is not a definite compound, but it is soluble. Its preparation consists in dissolving bismuth citrate in ammonia-water, evaporating (which also dispels all excess of ammonia) to a syrupy con- sistency, and spreading on plates of glass or porcelain, so that when dry the salt may be obtained in scales. The product should be kept in small well-stoppered bottles protected from light. The small shining, pearly scales are odorless and have a slightly metallic taste. They become 386 PHARMACEUTICAL AND MEDICAL CHEMISTRY. opaque and less soluble if exposed to the air, hence the Qecessity of keeping them in well-closed vessels. The presence of ammonia in the compound can easily be detected by boiling with soda or potassa solution, which liberates the ammonia, which may be detected by its odor. INDEX A Acetate of ammonium, solution, 204 — of iron and ammonium, solu- tion, 355 — of lead, 228 potassium, 181, 196 sodium, 196 zinc, 222 Acetic ether, 265 Acetylene, 59. 60 Acid, acetic, 58 — arsenic, 156 — arsenous, 156 — benzoic, 196 — boric, 107, 108, 109, 110, 113, 197 — bottle, 124 — chamber, 128 — chlorazotic, 144 — chloronitric, 144 — chromic, 158 — generator, 123 — hydj-iodic, 91, 148 — hydrobromic, 91 dilute, 145 — hydrobromic, Fothergill's, 146 — hydrochloric, 93, 139, 140 dilute, 144 — hydrocyanic, 65, 143, 247 — hydrofluoric, 86, 91 — hydrosulphuric, 91 — hyponitrous, 50 — hypophosphorous, 151 — iodic, 83 — iodous, 83 — metaphosphoric, 151 — nitric, 50, 134 dilute. 139 Acid, nitrohydrochloric, 144 dilute, 145 — nitromuriatic, 144 — nitrous, 50 — oleic, 241 — orthoboiic, 111 — orthophosphoric, 151 — oxalic, 217 — oxides, 115 — pan, 128 — periodic, 83 — phosphoric, 93, 102, 149 anhydrous, 151 glacial, 151 ortho, 151 varieties of, 151 — phosphorous, 149, 151 varieties of, 153 — pyroboric, 112 — pyrophosphoric, 112, 151 — prussic, 65 — sulphuric, 93, 125 aromatic, 131 dilute, 131 — tartaric, 96 — valerianic, 204, 322 — valeric, 204 Acids, 72 — chemically pure, 123 — dibasic, 130 — inorganic, 115 [125 — medicinal properties of the, — medicinally pure, 122 — monobasic, 120 — tribasic, 120 — antidotes to, 135 Acidulous radical, 95, 118 Air, 51 — chemical constituents of, 53, 54 387 288 IKDEX. Air, composition of air going into the lungs, 54 — composition of air coming out of the kings, 54 — pressure of the, 52 — pump, 52 — weight of, 52 Alchemy, 22 Aflfinity, simple elective, 77 Alkali, fixed, 173 — volatile, 173 — hypothetical, 173 Alkalies, 6, 172 — properties of the, 173 Alkaline earths, 6 — earth metals, 207 oxides, 115 Alkaloids, 49, 51, 61, 83 Allotropic forms of some ele- ments, 7, 56, 99, 100 Alloys, 160, 278 Aloes and iron pills, 257 Alum, 225 — ammonia, 225 — ammonio-ferric, 176, 262 — burnt, 225 — caesium, 176 — chrome, 176 — clay, 225 — dried, 225 — exsiccated, 225 — hydrous, 225 — iron, 176 (iron) — potassa, 225 — potassium, 225 Alumen, 225 Alumini hydras, 226 — sulphas, 226 Aluminum, 224 — hydrate, 226 — hydroxide, 225 — isolation of, 224 — properties of, 224 — salts, 224 impurities in, 225 — sulphate, 236 Alums, 175 Amalgamation, 234 Amalgams, 160 Ammonia, 199 — albuminoid in well-water, 45 — aromatic spirit of, 202 Ammonia aromatic precipitate in, 202 — generation of, in nature, 50 — in illuminating gas, 60 — in rain-water, 45 — in well-water, 45 — liniment, 202 — process for sodium bicarbon- ate, 191 — spirit, 202 — water, 201 stronger, 201 Ammoniacal gas-liquor, 200 — solution copper sulphate, 274 Ammoniated mercury, 239, 242 ointment of, 243 Ammonii Benzoas, 204 — bromidum, 204 — carbon as, 203 — chloridum, 201 — iodidum, 205 — nitras, 204 — valerianas, 204 Ammonio-ferric alum, 176, 262 citrate, 268 sulphate, 262 tartrate, 266 magnesium phosphate, 217 nitrate of silver solution, 275 — -sulphate of copper solution 274 Ammonium, 65, 177, 199 — acetate, solution of, 204 — benzoate, 204 — bicarbonate, 202, 203 — bromide, 204 — carbamate, 203 * — carbonate, 203 — chloride, 201 crude, 201 granular, 201 — iodide, 205 — nitrate, 204 granular, 204 — phosphate, 217 — salts, 199 impurities in, 201 — ' — properties of, 199 sources of, 200 tests for, 200 — ' valerianate, 204 Ammonia valerianate elixir, 205 INDEX. 289 Ammonia valerianate, commer- cial, 205 Amorphous, meaning of, 8, 56 Amyloses, 61 Analysis, 8, 35 — volumetric, 198 "Analytical reactions aluminum salts, 324 — ammonium salts, 200 — antimony salts, 278 — arsenic salts, 273 barium salts, 216 bismuth salts, 283 copper salts, 232 iron salts, 249 lead salts, 228 lithium salts, 206 magnesium salts, 217 mercury salts, 235 potassium salts, 178 silver salts, 245 — ' sodium salts, 190 strontium salts, 214 zinc salts, 220 Animal charcoal, 58 purified, 58, 143 — kingdom, 55 Animalculse, 46 Anhydrides, 116 Anhydrous salts, 38 Antacids, 114, 184, 218 — mild, 198 Antidotes to acids, 125 antimony salts, 283 arsenic salts, 157 lead salts, 228 mercury salts, 234 silver salts, 246 Antiferment, 194, 197 Antimonial powder, 282 Antimouiates, 278 Antimonii et potassii tartras, 282 — oxidum, 281 — sulphidum, 280 puriflcatum, 280 Antimonic compounds, 278 Antimonites, 278 Antimonium sulphuratum, 281 Antimoniuretted hydrogen, 273 Antimonous compounds, 278 — oxide, 282 Antimony, 278 — and potassium tartrate 282 — black, 278 — chloride, 282 — crude, 278 — oxide, 281 — oxychloride, 278, 282 — pills, compound, 281 — salts, 278 antidotes to, 283 occurrence of, 278 preparation of, 278 properties of, 278 — sulphide, 280 purified, 280 — sulphurated, 281 varieties of, 281 — tartarated, 282 — trioxide, 278 — wine of, 283 Antiferments, 111 Antiseptics, 194, 221, 226, 238 ] — dressings. 111 Antispasmodics, 222 Aputite, 208 Aqua-ammoniae, 201 fortior, 201 — chlori, 68, 78 Aquafortis, 138 Aqua-regia, 144 Arabic words gali and galaj, 173 Argeutum, 244 Argols, 178 Aromatic spirit of ammonia, 202 precipitate in, 202 — waters, 213 Arsenate of copper, 232 sodium, 194, 198, 277 solution, 198, 277 Arseni iodidum, 276 Arsenic, 270 — analytical reactions, 273 — antidote, 263 — and mercuric iodide solution, 277 — compounds, 271 similarity to phosphorus compounds, 271 — iodide, 276 — oxide, 270 — salts, 157, 270 290 IN^DEX. Arsenic, salts, occurrence of, 270 preparation of, 270 properties of, 270 — sulphides, 270 — test, Berzelius', 274 Fleitmann's, 274 Marsh's, 273, 279 Reinsch's, 274 — White, 275 Arsenical iron ores, 270 Arseuolite, 270 Arsenous acid, 275 solution, 276 — compounds, 270 — oxide, 156, 270, 275 antidote to, 157 preparation of, 157 properties of, 157 Arsenurelted hydrogen, 273 Atmosphere, 51 Atmospheres, 53 Atomic force, 3, 8 — weights of elements, 8, 10 standard, 12 Atomicity, 14 Atoms, 2 — definition of, 2 — kinds of, 3 Avogadro's law (lines 3-10), 10 Azote, 48 B Balsam tolu for coating pills, 259 Bandages, borated, 111 Barii dioxidum, 216 Barium, 216 — carbonate, 216 — chloride, 316 — dioxide, 216 — hydroxide, 216 — nitrate, 216 — salts, 216 — sulphocarbolate, 197 Barometer, 53, 234 Base for paints, 231 Bases, 95, 118, 119. 120, 164 — affinity of chlorine for, 77 Basham's mixture, 255 Basic bismuth carbonate, 167 chloride, 167 — ferric sulphate, 167 Basic ferric sulphate, solution of, 260 — mercuric sulphate, 243 — oxides, 115 — salts, 166, 283 Basylous radical, 95, 118 Bearer of light, 99 Beet-root sugar, 178 Benzoate of ammonium, 204 lithium, 206 sodium, 196 Benzoic acid, 196 Berzelius' test for arsenic, 274 Biborate sodium, 108 Bicarbonate of ammonium, 203 calcium, 41 lead, 229 potassium, 180 sodium, 193 commercial, 193 purified, 193 troches, 198 Binary theory of salts, 165 Biniodide of mercury, 239 By-products, 126 Birth of chemical science, 23 Bisalts, 95, 120 Bismuth, 283 — and ammonium citrate, 286 — citrate, 285 — group of metals, 6 — hydroxide, 283 — salts, 283 impurities in, 285 occurrence of, 283 properties of, 283 reactions of, 283 separation of arsenic in — preparation of, 284 — subcarbonate, 283 impurities, 285 — subnitrate, 283 preparation of, 284 — sulphide, 283 Bismuthi citras, 285 — et ammonii citras, 286 — subcarbonas, 283 — subnitras, 283 Bisulphite of sodium, 194 Bittern, 85 Bitter waters, 192 Bivalent atoms, 14 IJS^DEX. 291 Black antimony, 278 Bleaching agents, 198 — powder, 70, 79 Blowpipe, 109 — oxyhydrogen, 30 Blue mass, 336 — ointment, 236 — pill, 236 — stone, 232 — vitriol, 232 Bonds, 12, 13, 92, 93, 94, 95 Boneblack, 56 Bones, 97 Boracic acid, 110 Borated bandages. 111 — cotton, 111 — gauzes, 111 Borate of sodium, 107, 197 Borax, 107, 111, 112, 113 — and honey, 114 — bead, 109 — lakes, 112 — springs, 107, 108 — test for purity of, 113 Boric acid, 107, 108, 197 dusting-powder, 111 ointment, 111 tests for purity, 110 uses in pharmacy. 111 Boron, 107 — occurrence, 107 Brandt, chemist, 97, 99 Brass, 161 Braunatein, 22, 67, 269 Brines, 67, 85 Britannia, 161 Bromide of ammonium, 204 — calcium, 85, 209 — lithium, 206 — magnesium, 85 — potassium, 185 — sodium, 194 — strontium, 215 -^ zinc, 221 Bromides, 162 — test for, 86 Bromine, 85 — compounds of, 86 — occurrence of, 85 — preparation of, 85 — properties of, 86 — test for, 86 Bronze, 161 Brownstone, 22, 67 Burnt alum, 226 Caesium alum, 176 Cailletet, 49 Calamine, 220, 222 Calcination, 97 Calcined magnesia, 218 Calcite, 208 Calcii bromidum, 209 — carbonas prgecipitatum, 209 — chloridum, 209 — hypophosphis, 195, 212 — phosphas prsecipitatus, 213 Calcium, 207 — acid phosphate, 196 — bicarbonate, 41, 42 — bromide, 85, 209 — carbonate, 85, 209 precipitated, 209 — chloride, 94, 209 — fluoride, 86, 192 — hydrate, 78, 210, 212 solution, 210, 230 syrup, 211 — hydroxide, 78, 210, 212 — hypochlorite, 211 — hypophosphite, 195, 212 granular, 212 — lactophosphate, syrup of, 213 — metaphosphate, 99 — monosulphide, 211 — nitrate, 94 — phosphate, 94, 97, 98 precipitated, 213 — salts, 207 impurities in, 209 sources of, 208 Calcium sulphate, 94, 208, 211 — sulphide crude, 211 — tartrate, 178 Calcutta nitre, 188 Cali, 173 California cinnabar mines, 233 Calomel, 237, 238, 243 Calx, 210 — chlorata, 78, 179, 211 — sulphurata, 211 Cane-sugar, 57 Carbonate of ammonium. 203 292 INDEX. Carbohydrates, 33, 57, 60, 61 Carbon, 56 — active state in, 57 — compounds of, 56 — dioxide. 57, 61, 62 — disulphide, 60, 66 — monosulphide, 66 — monoxide, 60, 61 — occurrence of, 55 — properties of, 57 — with halogens, 65 — with hydrogen, 58 and oxygen, 60 nitrogen, 65 oxygen, 61 sulphur, 66 Carbonate of ammonium, 203 barium, 197 calcium, 18, 65 precipitated, 209 — ferrous, mass "of, 257 saccharated, 257 — of iron, 248 pills, 259 lead. 65, 231 ointment, 232 lithium, 206 magnesium, 65, 217 potassium, 179 sodium, 193 anhydrous, 193 crystalline, 193 . dried, 193 exsiccated, 193 zinc, 220 precipitated, 222 Carbonates, 56, 64 Carbonic acid, 62 how prepared, 63 properties of, 63 liquid, 64 gas, 56 Carron oil, 211 Catalysis, 24 Caustic, 210 — lunar, 245 — mild, 246 — potassa, 183, 194 antidote to, 183 solution, 194 — soda, 194 solution, 194 Cavendish, chemist, 28 Celestine, 214 Cellulose, 61 Cerate of subacetate of lead, 230 Ceratum plumbi subacetatis, 230 Cerium, 237 — compounds of, 227 — oxalate, 227 Chalk, 65, 208 — comp. powder of, 258 — drop, 208 — impurities in, 209 — mixture, 209 — prepared, 208 — troches, 209 Chalybeate tonic, 258 Chamber acid, 128 Charcoal, 7, 56, 58 — animal, 58 purified, 58, 143 — wood, 58 Charta potassii nitratis, 189 Chemical affinity, 3, 8 — constituents of the air, 53, 54 — force, 3 — nomenclature, 19 — notation, 15 — philosophy, 20 — union, 3 Chemism, 3 Chemistry, definition of, 3 — inorganic, 1 — organic, 56 Chili nitre, 79, 82 Chinese vermilion, 243 Chlorate of potassium, 187, 197 troches, 188 sodium, 197 Chlorates, 78 Chlorazotic acid, 144 Chloride of ammonium, 201 barium, 216 calcium, 209 — ferric, 253 solution, 254 tincture, 255 — of iron, 753 lime, 78, 79, 212 — mercuric, 234, 237 corrosive, 234, 237 — mercurous, 234, 237 IN'DEX. 293 Chloride, mercuric ammonium, 236 — of mercury, corrosive, 237 mild, 238 silver, 245 sodium, 195 zinc, 223 zinc solution, 223 Chlorides, 69, 78 — test for, 78 Chlorinated lime, 78, 211 Chlorination, 69 Chlorine, 66 — compounds, 70 — experiments with, 73 illustrating affinity for bases, 77 — experiments with, illustrating bleaching properties, 75 — experiments with, illustrating diffusion of gases, 74 — experiments with, illustrating disinfecting and deodorizing properties, 76 — experiments with, illustrating solvent power of chlorine, 77 — history of, 67 — in pharmacy, 78 — liquid, 69 — occurrence of, 6Y — oxides, 70 — preparation of, 67 — properties of, 68 — test of identity, 78 — with hydrogen and oxygen, 72 — water, 143 Chloronitric acid, 144 Chrom-alum, 176 Chromate of potassium, 190 strontium, 215 Chromic acid, 158 — oxide, 158 properties of, 158 uses of, 159 Chromium group of metals, 6 Cinnabar, 233 — from California mines, 233 Spain. 233, 243 Citrate ammonio-ferric, 268 — of bismuth, 285 and ammonium, 286 — ferric, 267 Citrate, ferric, solution, 266 wine, 268 — of iron, 267 and ammonium, 268 potassium, 261 quinine, soluble, 268 strychnine, 268 lithium, 207 magnesium, effervescent, 219 — of magnesium, solution of, potassium, 181, 219 effervescent, 182 mixture of, 182 solution of , 181 Citrine ointment, 244 Clarifying turbid water, 47 Clay-alum, 225 Coal, 56 — gas, 59 Cohesion, 1 Coin gold, 161 Coin silver, 244, 245 Coke, 56 Combustion, 62, 100, 102 Commercial bicarbonate of so- dium, 193 Compound antimony pills. 239, 281 — cathartic pills, 239 — chalk powder, 208 — iodine solution, 84 — iron mixture, 259 — radical, 65 — solution of iodine, 84 — iron mixture, 259 Compounds of carbon with hy- drogen, 58 — of carbon with hydrogen and oxygen, 60 — of carbon with oxygen, 61. cerium, 227 — ferric, 247 — ferrous, 247 Constant combining weight, 16 Constitutional formulae, 170 Contaminations in mercuric chloride, 237 Copper, 232 — acetate, 233 — and ammonium sulphate, so- lution of, 274 294 IliTDEX. Copper, arsenate, 233 — carbonate, 233 — group of metals, 6 — oxide, 35, 333 — salts, 333 impurities in, 333 reactions of, 78, 233 — sulphate, 232 — sulphide, 333 Copperas, 333 Corrosive chloride, 337 of mercury, 337 — sublimate, 337 Cotton, borated. 111 Creta prseparata, 308 Crude ammonium chloride, 201 — antimony, 378 — calcium sulphide, 311 Cryolite, 193, 193, 234 Crystals, dodecahedron, 99 — hexagon, 56 — monoclinic, 87 — octahedra, 56, 87 Cupri sulphas, 232 Cupric ferrocyanide — red, 333 — sulphate, 333 Cyanogen, 51, 65, 163 — iodide, 83 Cyanide of mercury, 343 potassium, 187, 190 silver, 346 Cyanides, 56, 65, 163 — double, 163 Decomposition of grain, 64 Definite quantities, 8 Deliquescence, 38 Density of metals, 160 Dentistry, anesthetic in, 50 Deodorizer, 76 Depilatory, 311 Destructive distillation, 51, 58, 59, 200 Dewar, physicist and chemist, 49 Dextrin, 61 Diachylon ointment, 230 — plaster, 230 Diads. 14 Diamond, 7, 56, 57 Diatomic, 14 Didymium, 227 Diffusion of gases, law of, 29 Dilute hydrobromic acid, 145 — hydrochloric acid, 144 — hydrocyanic acid, 65 — nitric acid, 139 — nitrohydrochloric acid, 145 — nitromuriatic acid, 145 — phosphoric acid, 155 — silver nitrate, 246 — solution lead subacetate, 229 — sulphuric acid, 131 Dioxide of barium, 216 manganese, 167, 269 Diphospboric acid, 151 Disease germs, 76 Disinfectant, 76, 79, 197, 232, 338 Dissociation, 19 Distillation, destructive, 51, 58, 59, 300 Disulphide of carbon, 66 Diuretic, 196 Donovan's solution, 377 Double salts, 95, 115, 130 Dried alum, 325 — ferrous sulphate, 256 — sodium carbonate, 193 E Effects of heat upon the molecu- lar forces, 32 Effervescence, 63, 113 Effervescent magnesium citrate, 219 — potassium citrate, 183 Efliorescence, 38 Elective affinity, 77 Elements, 34 — atomic weights of, 15 — chemical properties of, 8 — classification of, 5, 6 — definition of, 3, 4 — derivation of names of, 5 — forms of occurrence of, 7 — gaseous, 7 — groups and sub-groups, 5, 6 — halogen group of, 5 — liquid, 7, 233 — metallic, 6 — molecules of, 17 — names of, 5, 6 — uou -metallic, 21 INDEX. 295 Elements, oxygen group of, 5 — physical properties of, 7 — quantivalence of, 15 — symbols of, 5, 6, 15 — table of symbols, quantiva- lence, and atomic weights, 15 Elixir ammonium valerianate, 205 Elutriation, 208 Empirical formulas, 168 Emplastrum ammoniaci cum hy- drargyro, 237 — f erri, 264 — hydrargyri, 236 — plumbi, 23a Empyreumatic matter in ammo- nium carbonate, 203 Epsom salts, 217, 221 — springs, 216. 217 Equations, definition of, 18 — functions of, 19, 234 Equivalency, 14 Escharotic, 130, 210, 224, 246 Ether, acetic, 265 Ethylene. 59, 60 Experiments v^ith chlorine, 74 — illustrating its affinity for bases, 77 — illustrating its affinity for hy- drogen, 76 — illustrating its bleaching properties, 75 — illustrating diffusion of gases, 74 — illustrating disinfecting and deodorizing properties, 76 — with hydrogen, 30 Explosion, 70, 212 Explosives, 197 Exsiccated alum, 225 — ferrous sulphate, 256 — sodium bicarbonate, 193 Extract, Goulard's, 229 Fermentation, 64, 178 Ferri carbon as saccharatus, 257 — chloridum, 253 — citras, 267 — et ammonii citras, 268 sulphas, 262 tiirtras, 266 Ferri et potassii tartras, 261 quininge citras, 268 solubilis, 268 strychninse citras, 268 — hypophosphis, 259 — iodum saccharatum, 251 — lactas, 253 — oxidum hydratum, 263 cum magnesia, 262 — phosphas solubilis, 267 — pyrophosphas solubilis, 267 — sulphas, 256 exsiccatus, 256 granulatus, 256 — valerian as, 262 Ferric acetate solution, 264 tincture, 264 — alum, 262 — ammonium sulphate, 176, 263 — arsenate, 263 — chloride, 253 impurities in, 254 solution, 254 tincture, 255 — citrate, 267 solution, 266 wine, 268 — ferricyanide, 249 — ferrocyanide, 249 — hydrate 249, 263 — hydroxide, 263 antidote to arsenic salts, 263 — hydroxide with magnesia, 263 — hypophosphite, 154, 259 — nitrate, solution of, 265 — oxide, 248, 263 — oxyhydrate, 263 — phosphate, normal, 260, 267 soluble, 267 — pyrophosphate, 196, 267 soluble, 267 — subsulphate, solution of, 196, 260 — sulphate, basic, 260 solution, 261 — sulphocyanide, 249 — tannate, 249 — valerianate, 262 Feriicyanide of potassium, 249 Ferrocyanide of copper, red, 232 — of potassium, 186, 190, 249 296 INDEX. Ferrous arsenate, 263 — bromide, 195 — carbonate, mass of, 257 mixture of, 259 pills, 259 saccharated, 257 — compounds, 248 — hydrate. 263 — hydroxide, 263 — hypophosphite, 260 — iodide, pills of, 258 saccharated, 251 syrup of, 252 — lactate, 253 — sulphate, 256 dried, 256 exsiccated, 256 granulated, 256 — sulphide, 249 Ferrum, 248, 251 — reductum, 258 Flame, oxidizing, 109 — reducing, 110 Fleitmann's test for arsenic, 274 Flowers of sulphur, 88 Fluoride of calcium, 86 sodium and aluminum, 224 Fluorine, 86 Fluorspar, 86 Foam, 113 Forces, atomic, 3, 8 — of attraction, 2 — molecular, 1 — repulsive, 2 Forms of matter, 1 Formulas, constitutional, 170 Formulas, empirical, 168 — functions of, 19 — graphic, 20, 169, 176 — kinds of, 168 — molecular, 168 — of molecule of compounds, 18 elements, 17 — rational, 120, 169 — structural, 170 Fothergill's hydrobromic acid, 146 Fowler's solution, 182 Fiuit sugar, 61 Fuming sulphuric acid, 131 Functions of equations, formu- las and symbols, 19, 134 Fused silver nitrate, 246 G Galena, 227 Gali, 173 Gas carbon, 56 — illuminating, 51, 59, 200 — laughing, 50, 204 — liquor, ammoniacal, 200 — olefiant, 59 Gases, 2 — densities of, 74 — diffusion, law of, 29, 74 — equal volumes of, 9, 17 — proportion of, by weight, 9 volume, 9 Gauzes, borated. 111 German silver, 161 Germs, disease, 76 Glacial acetic acid, 264 — phosphoric acid, 151 Glass, soluble, 198 Glasswort, 172 Glauber's salt, 128 Glycerin, 230 Glucoses, 60 Glucosides, 61 Goebel's- Glover's method for hy- drobromic acid, 146 Gold coin, 161 — leaf, 77 Goulard's cerate, 230 — extract, 229 Granular ammonium chloride, 201 — ammonium nitrate, 204 — ferrous sulphate, 256 — zinc, 220 chloride, 221 Grain, decomposition of, 64 Grape-juice, 188 — sugar, 61 Graphic formulas, 120, 169, 170 Graphite , 56 Greeu iodide of mercury, 240 Griffith's mixture, 259 Gypsum, 208 H Hgemostatic, 261 Hair restorer, 231 INDEX. 297 Halogens, 66 Haloid salts, 162 Heat, effect upon molecular forces, 32 — specific, 39 Heavy carbonate of magnesium, 218 — magnesia, 218 Hexads, 14 Hexagons, 56 Honey and borax, 114 Horn silver, 244 Hydracids, 116, 122 Hydrargyri chloridum corro- sivum, 234 mite, 234 — cyanidum, 242 — iodidum flavum, 240 rubrum, 239 viride, 240 — oxidum flavum, 241 rubrum, 241 — subsulphas flavus, 243 Hydrargyrum, 233 — ammoniatum, 239 — cum creta, 237 Hydrate of barium, 216 bismuth, 283 calcium, 78, 210, 212 solution, 210, 230 — ferric, 157, 249, 263 — ferrous, 263 — of iron, 157, 249, 263 with, magnesia, 157, 263 lead, 227 magnesium, 217 potassium, 183, 190 solution , 183 — silicious, of magnesium, 216 — of sodium, 193 solution, 194 zinc, 222 Hydrated alumina, 225, 226 — oxide of iron, 263 Hydrates, 33, 37 Hydrides, 33 Hydriodic acid, 148 properties of, 148 syrup of, 148 uses of, 149 Hydrobromic acid, dilute, 145 Hydrobromic acid, Fothergill's, 146 Goebel's- Glover's method for preparation of, 146 impurities in , 147 preparation of, 145 properties of, 145 Squibb's, 147 test of identity, 147 Wade's Buchanan's, 146 uses of, 147 Hydrochloric acid, 139 antidote, 143 dilute, 144 impurities in, 143 preparation of, 140 properties of, 140 test for, 140 type, for salt, 93 uses of, 143 Hydrocyanic acid, dilute, 65, 143, 147 Hydrocarbons, 33, 57, 58, 61 — substitution derivatives, 59 — volatile liquid, 60 Hydrofluoric acid, 86, 91 Hydrogen, 28 — antimonuretted, 273 — arsenuretted, 273 — chemical energy of, 31 properties of, 30 — compounds, 33 — etymology of word, 25 — experiments with, 30 — history of, 28 — is it a metal ? 31 — neutralizing qualities, chemi- cally, 31 — occurrence in nature, 28 — peroxide of, 47 — physical properties, 29 — preparation of, 28 — phosphoretted, 195, 212 — sulphide of, 91, 96 — sources, 28 — tests and experiments with, 30 — uses in pharmacy, 32 Hydrosulphuric acid, 91, 96 Hydrous alum, 225 Hydroxide of aluminum, 225, 226 — of barium, 216 298 IKDEX. Hydroxide of bismuth, 283 calcium, 78, 210, 212 solution, 210, 230 — ferric, 159, 249, 263 — ferrous, 263 — of iron, 249, 263 with magnesia, 157, 262 lead, 227 magnesium, 217 potassium, 183, 190 solution, 184 sodium, 193 solution, 194 zinc, 222 Hydroxides, 33, 37 Hypnotics, 207, 210 Hypo, photographers', 198 Hypochlorite of calcium, 211 Hyponitrous acid, 50 Hypophosphite of calcium, 154, 195, 212 — ferric, 154, 259 — of potassium, 154, 183 sodium, 154, 195, 197 Hypophosphites, syrup of, 195, 213 Hypophosphorous acid, 151, 154 Iceland spar, 208 Illuminating gas, 51 composition of, 59 purification of, 60 Impenetrability, 51 Imperial green, 278 Impurities in aluminium salts, 225 — in ammonium salts, 201 bismuth salts, 285 subcarbonate, 285 subnitrate, 285 calcium salts, 209 copper salts, 233 ferric chloride, 254 hydrobromic acid, 147 hydrochloric acid, 142, 143 iodine, 82 lead salts, 228 lithium salts, 205 magnesium salts, 217 mercury salts, 234 potassium salts, 179 Impurities in silver salts, 245 sodium salts, 190 strontium salts, 213 zinc salts, 220 Incompatibility, 185 Indigo, 69 Inorganic acids, 115 handling of, 124 medical properties of, 125 — chemistry, 1 Introduction, 1 lodate of potassium, 185 sodium, 195 lodates, 84 Iodic acid, 83 Iodide of ammonium, 205 arsenic, 276 and mercury, solution of, 277 cyanogen, 82 — , ferrous, pills, 258 saccharated, 257 syrup, 252 — of lead, 231 ointment, 231 — mercuric, red, 239 — mercurous, yellow, 240 — of mercury, green, 240 red, 239 yellow, 240 potassium, 185 silver, 247 sodium, 195 starch, 142 strontium, 215 sulphur, 190 zinc, 221 Iodides, 83, 163 — test for, 85 Iodine, 80 — chloride of, 82 — compounds, 83 — compound solution of, 84 — impurities in, 82 — ointment, 84 — pharmaceutical preparations of, 83 — preparation of, 81 — properties of, 83 — purification of, 82 — sources of, 80 — test for, 85 INDEX. 299 Iodine, tincture of, 83 Iodized starch, 84 lodous acid, 83 Iron, 248, 251 — acetate , solution of, 264 tincture of, 264 — and aloes, pills, 207 — alum, 176, 262 — and ammonium acetate solu- tion, 255 — and ammonium citrate, 268 tartrate, 266 — arsenate, 263 — bitter wine of, 268 — bromide, 195 — carbonate, mass of, 257 mixture of, 259 pills of, 259 saccbarated, 257 — chloride, 253 impurities in, 254 solution, 254 tincture, 255 — citrate, 267 solution, 266 wine, 268 — compounds of, 248 analytical reactions of, 249 — ferricyanide, 249 — ferrocyanide, 249 — group of metals, 6 — hydrate, 249, 263 — hydroxide, 263 antidote to arsenic salts, 263 — hydroxide, with magnesia, 263 — hypophospbite, 154, 259, 260 — iodide, pills of, 258 ■ saccbarated, 251 syrup, 252 — lactate, 253 — metallic, 248, 251 — nitrate, solution, 265 — oxide, 248, 263 — oxybydrate, 267 . — persulphate, solution, 261 — pbosphate, normal, 260, 267 soluble, 267 — pills, 259 — plaster, 264 — and potassium tartrate, 266 — pyrophosphate, 146, 267 soluble, 267 Iron and quinine citrate, soluble, 268 — quinine and strychnine phos- phate, syrup, 267 — and strychnine citrate, 268 — reduced, 251 — salts, 247 order of derivation, 249 properties of, 248 sources, 247 — scale salts, 265 — subsulpbate solution, 196, 260 — sulphate, 256 basic, 260 dried, 256 exsiccated, 256 granular, 256 — sulphides, 249 — sulphocyanide, 249 — tannate, 264 — tersulphate solution, 261 — troches, 264 — valerianate, 262 — wire, 251 Is hydrogen a metal? 81 Javelle water, 80 Juice, grape, 188 K. Kalium, 6 Kelp, 81 Kermes' mineral, 281 Kinds of atoms, 3 formulas, 168 L. Labarraque's solution, 79, 112 Laborde, French physiologist, 218 Lactate of iron, 253 strontium, 216 Lac sulphur, 90 Lactophosphate of calcium syrup, 213 Lampblack, 56, 57 Lanthanum, 227 Laughing-gas, 50, 204 Lavoisier, chemist, 21 Law of definite chemical propor- tion, 8 — of diffusion of gases, 29 300 IlfDEX. Law of multiple chemical propor- tion, 10, 62 Lead, 57, 327 — acetate, 228 commercial, 229 — bicarbonate, 227 — carbonate, 231 ointment, 232 — hydrate, 227 — hydroxide, 227 — in water, 227 — iodide, 231 ointment, 231 — nitrate, 230 — oleate, 230 — oxide, 228 — oxyacetates, 229 — plaster, 230 — properties of metal, 227 — salts, 227 antidotes to, 228 sources, 229 — subacetate, cerate, 230 liniment, 230 solution, 229 solution, dilute, 229 — sugar of, 229 — water, 229, 230 — white, 231 Le Blanc's process for sodium bicarbonate, 141, 191, 192 Lepidolite, 206 Lesson in nomenclature, 71 Light magnesia, 218 — magnesium carbonate, 218 Lime, 210 — chloride of 78, 213 — chlorinated, 211 — liniment, 211 — slaked, 78, 212 Limestone, 65, 208 Lime, sulphurated, 311 — syrup, 210 — water, 210, 230 Liniment, ammonia, 202 — lime, 211 — of subacetate of lead, 230 — volatile, 202 Linimentum ammoniae, 202 — calcis, 211 Liquid elements, 233 — volatile hydrocarbons, 60 Liquor acidi arsenosi, 276 — Ammonii acetatis, 204 — arseni et hydrargyri iodidi, 277 — calcis, 230 — ferri acetatis, 264 chloridi, 254 citratis, 266 et ammonii acetatis, 255 subsulphatis, 260 tersulphatis, 361 — hydrargyri nitratis, 244 — iodi compositus, 84 — magnesii citratis, 318 — plumbi subacetatis, 229 dilutus, 229 — potassae, 184 — potassii arsenitis, 182 citratis, 181 — sodae, 194 chloratse, 198 — sodii arsenatis, 198 silicatis, 198 — zinci chloridi, 223 Litharge, 228 Lithii benzoas, 306 — bromidum, 306 — carbonas, 306 — citras, 307 — salicylas, 307 Lithium, 305 — benzoate, 306 uses of, 306 — bromide, 206 — carbonate, 206 — citrate, 207 — properties of, 205 — salicylate, 207 Lithium salts, 205 impurities in, 205 sources, 206 tests, 206 Litmus, 70, 76 Liver of sulphur, 183 Lixivia tiou, 81 Lugol's solution, 84 Lunar caustic, 245 M. Magnesia, 216 — alba, 217 — calcined, 218 IKDEX. 301 Magnesia, heavy, 317 — light, 217 — nigra, 217 — ponderosa, 218 Magnesii carbonas, 217 — citras effervescens, 219 — sulphas, 217 Magnesium, 216 — bromide, 85 — carbonate, 65, 217 heavy, 218 light, 218 — citrate, effervescent, 219 solution, 218 — group of metals, 6 — hydrate, silicious, 216 — hydroxide, 218 — silicious hydrate, 216 — sulphate, 94, 217 impurities in, 217 — sulphite, 219 Magnetic oxide of iron, 248 Manganese, black oxide, 22, 67, 217, 269 — carbonate, 269 — dioxide, 22, 67, 217, 269 — sulphate, 269 Mangani, dioxidum, 269 — sulphas, 269 Marble, 65, 208 Marine plants, 80 Marsh gas, 59, 60 Marsh's test for arsenic, 273, 279 Mass, blue, 276 — ferrous carbonate, 258 — mercury, 236 — vallets, 258 Massa ferri carbon atis, 258 — hydrargyri, 236 Matches, manufacture of, 103 Matter, ultimate kinds of, 3 Mercur- ammonium chloride, 242 Mercurial ointment, 236 — plaster, 236 Mercuric ammonium chloride, 239 — chloride, corrosive, 237 in calomel, 239 — cyanide, 232 — iodide, red, 239 — nitrate ointment, 244 solution, 244 Mercuric oxalate, 342 — oxide, red, 241 ointment, 242 yellow, 241 ointment, 241 — subsulphate, yellow, 243 — sulphate, basic, 243 — sulphide, 243 Mercurous chloride, mild, 338 — iodide, yellow, 240 — nitrate, 240 — sulphate, 238 Mercury, ammoniated, 239, 342 ointment, 243 — biniodide, 239 — chloride, corrosive, 237 mild, 238 — compounds of, 233 mercuric, 234 mercurous, 234 reactions of, 235 — cyanide, 242 — iodide, green, 240 red, 239 yellow, 240 — metallic, 233 — impurities in, 234 — preparations of, 233 — properties of, 234 [ing, 236 — metallic, preparations contain- — nitrate, 235 ointment, 244 solution, 244 — oleate, 236, 241 — oxide, red, 341 ointment, 343 yellow, 341 ointment, 341 — protiodide, 240 — salts of, 233, 237 antidote to, 234 reduction of, 239 — sulphate, basic, 243 yellow, 243 — sulphide, 233 red, 243 — with chalk, 237 Meta, 152 Meta-arsenate of potassium, 373 — arsenates, 373 arsenic acid, 372 arsenite of potassium, 272 302 INDEX. Meta-arsenites, 273 — -arsenous acid, 272 phosphate of potassium, 272 phosphates, 153 phosphite of potassium, 272 phosphoric acid, 272 phosphorous acid, 272 Metal, hypothetical, 199 Metalloids, 5, 21, 271 Metals, 5, 6, 160 — alkali group, 6 — alkaline earth group, 6 — bismuth group, 6 — chromium group, 6 — copper group, 6 — chemical properties of, 160 — densities of, 160 — difference from non-metals, 21 — ductility of, 160 — iron group, 6 — magnesium group, 6 — monad, 94 — platinum group, 6 — physical properties of, 160 — unions with the halogens, 162 — volatility of, 160 Methane, 59, 60 Miasms, 76 Mild chloride of mercur}'', 238 Milk sugar, 61 — of sulphur, 90 Mindererus' spirit, 204 Mineral acids, 15 antidotes to, 125 — turpeth, 243 Mispickel, 270 Mistura cretae, 209 — ferri composita, 259 — potassii citratis, 182 — rhei et sodse, 199 Mitigated silver nitrate, 246 Mixture, Basham's 255 — chalk, 209 — compound iron, 259 — Griffith's, 259 — rhubarb and soda, 199 Molecular forces, 1, 2 ejffect of cold and heat upon, 32 Molecules, 2, 17 — definition of, 2 — internal structure of, 3 Molecules, resolution of, 3 Monad metals, 94 Monads, 14, 94 Monatomic, 14 Mouocalcic phosphate, 98 Monoclinic crystals, 87 Monosulphide of calcium, 211 Mousel's solution, 260 Multiple chemical proportions, law of, 10 Muriatic acid, 139 dilute, 144 N. Names, chemical, 71 Natrium, 6 Natural forces, 1 — philosophy, 2 — reciprocity, 55 Nessler's reagent, 45, 200 Neutral mixture, 182 — salts, 95, 164 Nitrate of ammonium, 204 barium, 216 — ferric, solution, 265 — of lead, 230 — mercuric, ointment, 244 solution, 244 — of potassium, 189 paper, 189 silver, 245 impurities in, 245 dilute, 246 fused, 246 mitigated, 246 sodium, 94, 192, 197 Nitrates and nitrites in w^ll- water. 44, 45 — test for, 51 Nitre, 138, 189 — Calcutta, 178, 189 — Chili. 49 Nitric acid, 50, 134 dilute, 189 impurities in, 138 preparation of, 134 properties of, 137 Nitrites in well-water, 44, 45 Nitrogen, 48 — compounds of, 49 — function in nature, 49 — history of, 48 INDEX. 303 Nitrogen, liquid, 49 — occurrence, 48 — oxides, 50 — preparation of, 49 — properties of, 49 Nitrohydrochloric acid, 144 dilute, 145 Nitromuriatic acid, 144 dilute, 145 Nitrosylchloride, 144 Nitrous acid, 50, 134 — oxide, 50, 204 Nomenclature, chemical, 19, 71 Non-metallic elements, 21 Non-metals, 5, 6, 21 diii'erence from metals, 21 halogen group, 5 oxygen group, 5 Nordhausen sulphuric acid, 131 Normal bismuth carbonate, 167 — ferric nitrate, 265 phosphate, 267 sulphate, 167 tartrate, 266 — sodium sulphate, 167 Notation, chemical, 15 O. Octahedra, 56, 87 Official sulphurs, 88 Oil, carron, 21 Ointment, blue, 236 — citrine, 244 — diachylon, 230 — iodine, 84 — lead carbonate, 232 iodide, 231 — mercurial, 236 — mercuric nitrate, 243 — mercuric oxide, red, 242 yellow, 241 — mercury ammoniated, 243 — red precipitate, 242 — sulphur, 91 — zinc oxide, 222 Oleate of lead, 230 mercury, 236, 241 propenyl, 230 Oleatum hydrargyri, 241 Oleic acid, 241 Order of derivation of iron salts, 249 Ores, arsenical iron, 270 Organic chemistry, 58 — matter in water, 44 Orpiment, 270 Ortho, 152 Ortho -arsenates, 273 Ortho-arsenites, 273 — -boric acid, 111 — compounds, 272 phosphoric anhydride, 151 acid, 149, 151 Oxalate of cerium, 227 mercury, 242 Oxalic acid, 217 Oxidation, 24, 26, 50, 62, 69 Oxide of antimony, 281 arsenic, 270, 275 copper, 232 — ferric, 248 — of iron, 248 lead, 228 magnesium, 248 manganese, black, 22, 67, 217, 269 — mercuric, red, 241 yellow, 241 — of phosphorus, 100, 153 silica, 98 silver, 245, 247 pills, 247 zinc, 222 Oxides, 26, 115 — acid, 115 — alkaline, 115 — basic, 115 — of chlorine, 70 nitrogen, 50 non-metals, 72 — of phosphorus, 100, 102, 103, 153. — similarity to sulphides, 88 Oxidizing flame, 110 Oxyacetate of lead, 229 Oxyacids, 116 Oxvchlorides, 162 Oxysalts, 163, 167 Oxygen, 21 — and nitrogen as the atmos- phere, 51 — chemical properties of, 24 — discovery of, 21 — etymology, 25 304 IKDEX. Oxygen, experiments with, 24 — group of elements, 5 — history of, 21 — occurrence in nature, 22 — acids, 116 — physical properties of, 23 — preparation of, 23 — relation to plant and animal kingdom, 23 — tests, 26 — uses in pharmacy of, 26 Oxyhydrogen blowpipe, 30 Oyster shells, 208 Ozone, 7, 27, 57 — test for in atmosphere, 27, 101 Paints, base for, 231 Pan acid, 128 Paracelsus, 28 Paraf-javal, chemist, 214 Paraphenolsulphonate of sodi- um, 196 Paris green, 277 Pentads, 14 Penatomic atoms, 14 Per-iodic acid, 83 Permanganate of potassium, 184 Peroxide of barium, 216 hydrogen, 47 Persalts, 33 Persulphate of iron solution, 261 Pewter, 278 Philosophy, chemical, 20 — natural, 2 Phosphate of aluminum, 96 calcium, 96, 97 precipitated, 213 iron, 96, 248, 260 soluble, 267 — monocalcic, 98 — of potassium, 96 sodium, 94, 153, 196 — tricalcic, 97, 98 Phosphates, 96 — of iron, quinine, and strj-^ch- nine syrup, 267 Phosphide of zinc, 224 Phosphites, 153 Phosphorated oil, 105 Phosphoretted hydrogen, 195, 212 Phosphoric acid, 93, 102, 107, 149 Phosphoric acid, anhydrous, 151 dilute, 155 glacial, 151 ortho-, 149,151 varieties of, 151 — oxide, 100, 102, 103, 153 Phosphorous acid, 149, 151 varieties of, 153 Phosphorus, 96 — active state of, 100 — allotropic forms of, 100 — amorphous, 100 — antidote to, 101 — black, 100 — crystalline, 100 — experiments with, 101 — medical properties of, 106 — occurrence in nat\ire, 96 — passive state of, 100 — pills, 106 — poisonous properties of, 101 — preparation of, 97 — properties of, 99 — red, 100 — sources of, 97 — white, 100 — uses of, 103 in medicine and phar- macy, 104 Photographers' " hypo," 198 Physical properties of elements, 7 metals, 166 Physics, 1, 2 Pictet, physicist, 49 Pills, aloes, and iron, 257 — antimony, compound, 281 — Bland's, 259 — cathartic compound, 239 — ferrous iodide, 258 — of iron carbonate, 259 phosphorus, 106 — Plummer's, 281 — of silver oxide, 247 Pilulse ferri carbonatis, 258 Plant-food, 97 Plaster, diachylon, 230 — iron, 64 — lead, 230, 237 — mercury, 236 and ammoniac, 237 Platinum group of metals, 6 INDEX. 305 Plumbi acetas, 228 — carbonas, 231 — iodidiim, 231 — nitras, 230 — oxidum, 228 Plummer's pills, 281 Polishing rouge, 132 Potash, caustic, 183 Potassa, 183 — by alcohol, 183 — caustic, 183 antidote, 183 — cum calce, 184 — solution, 184 — sulphurata, 182 — sulphurated, 182 — liquor, 184 — with lime, 184 Potassi acetas, 181, 196 — bicarbonas, 180 — bichromas, 187 — bitartras, 178, 188 — bromidum, 185 — carbonas, 179, 180 — chloras, 187 — citras, 181 effervescens, 182 — cyanidum, 187, 190 — et sodii tartras, 188 — ferrocyanidum, 186, 190 — hypophosphis, 183 — iodidum, 185, 190 — nitras, 189 — permanganas, 184 Potassio-citrate of iron, 265 — ferric tartrate, 266 Potassium, 177 — acetate, 181, 196 — alum, 225 — and sodium tartrate, 188 — anhydrochromate, 168 — arsenite, solution, 182, 276 — bicarbonate, 180 — bichromate, 187 antidote, 187 — bitartrate, 178, 188 — bromide, 185 — carbonate, 179, 190 — chlorate, 187 troches, 188 — chromate, 190 — citrate. 181. 219 Potassium citrate effervescent, 182 mixture, 182 solution, 181 — chloride, 179 — cyanide, 187, 190 — dichromate, 190 — f errocyan ide, 249 — ferricyanide, 186, 190, 249 — hydrate, 190 solution, 184 — hydroxide, 190 solution, 1 84 — hypophosphite, 154, 183 syrup of, 183 impurities in, 179 — iodide, 185, 190 — meta-arsenate. 272 arsenite, 272 — metaphosphate, 272 — metaphosphite, 272 — nitrate, 189 paper, 189 — permanganate, 184 — prussiate, yellow, 186 — salts, 177 impurities in, 179 sources of, 177 tests for, 178 — sulphate, 190 — sulphite, 180 — sulphocyanide, 190 — tartrate, 188 Powder, bleaching, 70, 79 — chalk compound, 208 — tooth, 209 — zinc, 220 Precious stones, 224 Precipitate, red, 242 ointment, 242 — white, 243 ointment, 243 Precipitated calcium carbonate, 209 — calcium phosphate, 213 — sulphur, 88, 89 — zinc carbonate. 222 Prefixes, 11, 14, 33, 71, 73 Prepared chalk, 208 Preparations containing metallic mercury, 236 Primary products, 125 306 INDEX. Propenyl oleate, 230 Proportion, definite chemical, 8 — multiple, law of, 10 Protiodide of mercury, 240 Piusslate of potash, yellow, 186 Prusslc acid, 65 Pseudotriad, 176, 224 Pump, air, 52 Purified animal charcoal, 143 — sodium bicarbonate, 193 — sulphide of antimony, 280 Putrefaction, 64, 79 Pyrites, iron, 87, 129 Pyro, 112 Pyroboric acid, 112 Pyroacids, 272 Pyroarsenic acid, 273 Pyroarsenous acid, 273 Pyrolusite, 269 Pyrophosphate of iron, 196 soluble, 267 sodium, 196 Pyrophosphates, 153 Pyrophosphites, 153 Pyrophosphoric acid, 112, 152 Pyrophosphorous acid, 151 — oxide, 153 Pyrosalts, 272 Quadrads, 14 Quadrivalent atoms, 14 Quantivalence, 12 R. Radical, 95, 118, 164 — acid, 95, 118 — basylous, 95, 118 Rational formulas, 120, 169 Reactions, analytical, of alumi- num salts, 224 ammmonium salts, 200 antimony salts, 278 arsenic salts, 273 barium salts, 216 bismuth salts, 283 bromides, 86 bromine, 86 carbonates. 63 chlorides, 78 copper salts, 232 ferric salts, 248, 249 Reactions, analytical, of ferrous salts, 248, 249 hydrochloric acid, 140 iodides, 85 iodine, 85 iron salts, 249 lead salts, 228 lithium salts, 206 magnesium salts, 217 mercuric salts, 235 mercurous salts, 235 metaphosphates, 152 nitrates, 51 phosphates, 152 potassium salts, 178 pyrophosphates, 152 silver salts, 245 sodium salts, 190 starch, 85, 142 strontium salts, 214 sulphates, 257 tannic acid, 249 zinc salts, 220 Reagent, Nessler's, 45, 200 Realgar, 270 Red cupric ferrocyanide, 232 — mercuric iodide, 239 oxide, 241 ointment, 241 — phosphorus, 100 — precipitate, 241 ointment, 242 Reduced iron, 258 Reducing flame, 110 Reinsch's test for arsenic, 274 Regia, 144 Repulsion, 2 Resolution, chemical, 18 — of molecules, 3 Resublimation, 82 Rex, 144 Rhubarb and soda mixture, 199 Rochelle salt, 95, 166, 188 Rouge, polishing, 132 Rule of three, 226 S. Saccharated carbonate of iron, 257 — iodide of iron, 251 Saccharoses, 61 Sal ammoniac, 201 INDEX. 307 Salicylate of lithium, 207 sodium, 196 Sand, 98 Salt, common, 94, 195 — Rochelle, 95, 166, 188 Saltpetre, 189 Salts, 73, 94, 115 — acid, 95, 164, 166 — aluminum, 224 — ammonium, 199 — anhydrous, 38 — antimony, 278 — arsenic, 270 — barium, 216 — basic, 164, 167 — binary theory, 165 — bismuth, 283 — copper, 232 — deliquescent, 38 — double, 95, 115, 120, 166 — efflorescent, 38 — haloid, 162 — iron, 247 scale, 265 — magnesium, 216 — mercury, 233, 237 — metallic, 164 — neutral, 95, 164 — normal, 166 — oxygen, 163 — potassium, 177 — silver, 244 — sodium, 190 — strontium, 213 — types, 91 — writing of, 91 — zinc, 220 Scale salts of iron, 265 Scheele, Carl, 21, 67 Scheele's green, 275 Scrubber, 60 Septads, 14 Serpentine, 217 — rocks, 216 Sheep's wool, 178 Shells of cretaceous animals, 65 Shot, 161 Silicate sodium, 198 solution, 189 Silicious hydrate of magnesium, 216 Silver. 244 Silver, analytical reactions of, 245 — chloride, 245 — coin, 244, 245 — cyanide, 246 — iodide, 247 — leaf, 244 — nitrate, 245 dilute, 246 fused, 246 impurities in, 245 mitigated, 246 — occurrence, 244 — oxide, 245, 247 pills, 247 — properties of, 244 — salts, 244 antidote to, 246 Simple elective affinity, 77 — substances, 3 Slaked lime, 78, 212 Soap, action of, upon hard waters, 42 Soda, 194 — ash, 141 — caustic, 193 solution, 194 stick, 193 — chlorinated, solution, 198 — liquor, 194 — and rhubarb mixture, 199 — water, 63 Sodii, acetas, 196 — arsenas, 194 — benzoas, 196 — bicarbonas, 193 — bisulphis, 194 — boras, 197 — bromidum, 194 — carbonas, 192 exsiccatus 193 — chloras, 197 — chloridum, 195 — hypophosphis, 195 — hyposulphis, 197 — iodidum, 195 — nitras, 197 — phosphas, 196 — pyrophosphas, 153 — salicylas, 1 96 — sulphas, 197 — sulphis, 194 308 INDEX. Sodii sulphocarbolas 196 Sodium, 190 — acetate, 196 — aluminate, 192 — and aluminum fluoride, 224 — anhydrosulphate, 168 — antimonite, 279 — arsenate, 194, 198 solution, 198, 227 — benzoate, 196 — biborate, 108 — bicarbonate, 95, 192, 193 commercial, 193 purified, 193 troches, 198 — bisulphite, 194 — borate, 108, 192, 197 — bromide, 194 — carbonate, 192 anhydrous, 193 crystalline, 193 dried, 193 exsiccated, 193 — chlorate, 192, 197 — chloride, 94, 195 — hydrate, 193 solution, 194 — hydroxide, 193 solution, 194 — hypophosphite, 195 — hyposulphite, 192, 197 — iodate, 196 — iodide, 195 — metaphosphate, 153 — nitrate, 94, 192. 197 — paraphenolsulphonate, 196 — phosphate, 94, 153, 196 — phosphite, 153 — pyrophosphate, 153 — salicylate, 196 — salts, 190 — silicate, 198 — sulphate, 94, 128, 192 — sulphite, 194 — sulphocarbolate, 196 — thiosulphate, 197 Soil, 97 Solid sulphuric acid, 132 Soluble glass, 198 — iron and quinine citrate, 268 — ferric phosphate, 267 — ferric pyropliosphate, 267 Solution Ammonium Acetate, 204 and iron acetate, 255 — arsenate sodium, 198 — arsenic and mercuric iodides, 277 — arsenite potassium, 182, 276 — arsenous acid, 276 — basic ferric sulphate, 260 — calcium hydrate 210, 230 — chlorinated soda, 80, 198 — Donovan's, 277 — ferric acetate, 264 chloride, 254 citrate, 266 nitrate, 265 subsulphate, 260 sulphate, 261 — Fowler's, 182, 276 — iodine compound, 84 — iron citrate, 266 — Labarraque's, 79, 212 — lead subacetate, 229 dilute, 229 — lime, 210, 230 — Lugol's, 84 — magnesum citrate, 218 — mercuric nitrate, 243 — Monsel's, 260 — potassa, 184 — potassium arsenite, 182, 276 citrate, 181 hydrate, 184 — soda, 194 — sodium arsenate, 198, 277 hydrate, 194 silicate, 198 — zinc chloride, 233 Solvay process, 191, 193 Soot, 56, 57 Spain, cinnabar mines in, 233 Specific heat, 39, 40 Spirit of ammonia. 202 aromatic, 202 Mindererus, 204 Spodumene, 206 Spontaneous inflammation, 103 Squibb 's process for hydrobro- mic acid, 147 Stalagmites, 208 Standard of atomic "weights, 12 Starch-test, 142 INDEX. 309 Starch, iodized, 84 Starches, 61 Steel as reagent, 78 Strassfurt mines, 178, 180 Stronger water of ammonia, 201 Strontianite, 214 Strontii bromidum, 215 — iodidum, 215 — lactas, 216 Strontium, 213 — bromide, 214, 215 — chromate, 215 — iodide, 214, 215 — lactate, 214. 216 — salts, 213 properties and tests of, 214 Structural formulas, 170 Study of acids and salts, 115 Styptic, 262 Subacetate lead cerate, 230 liniment, 230 solution, 229 dilute, 229 Sublimate, corrosive, 237, 238 Sublimed sulphur, 88, 89 Subchloride of mercury, 238 Subcarbonate of bismuth, 283 Subuitrate of bismuth, 283 Substitution derivatives of hy- drocarbons, 59 Subsulphate of iron solution, 260 mercury, 243 Suffixes, 73 Sugar, beet-root 178 — block. 58 — cane, 57, 58 — fruit, 61 — grape, 61 — granulated, 58 — of lead, 229 milk, 61 Sulphate of aluminum, 326 barium, 87 calcium, 87 copper, 232 — ferric, basic solution, 260 solution, 261 ammonium, 262 — ferrous, 256 dried, 256 granulated, 256 Sulphate of magnesium. 94, 217 manganese, 269 mercury, basic, 237 potassium, 190 sodium, 94, 128, 192 zinc, 220 Sulphide of antimony, 280 purified, 280 arsenic, 270 copper, 87, 232 hydrogen, 91, 96 iron, 87, 248 lead, 87 mercury, 87 red, 243 zinc, 220 Sulphides, 87, 91, 96 — similarity to oxides, 88 Sulphocarbolate of barium, 197 sodium, 196 Sulphocyanide of iron, 249 Sulphur. 87, 96 — alkaline ointment, 91 — crude, 87 — flowers of, 88 — iodide, 90 — milk of, 90 — occurrence of, 87 — precipitated, 88, 89 — preparation of, 87 — properties of, 87 — sublimatum, 88 — sublimed, 88, 89 — washed, 88, 89 — with hydrogen, 91 Sulphurated antimony, 281 • — lime, 211 — potassa, 182 Sulphuric acid, 125 — aromatic, 131 — dilute, 131 — solid, 132 Sulphurous acid, 133 Sulphurs, official, 88 Supporter of combustion, 31 Symbolizing chemical facts, 16 Symbols, 15, 16 — functions of, 16, 19 Synthesis, 18, 35 Syrup of calcium lactophos- phate, 213 ferrous iodide, 252 310 INDEX. Syrup of hydriodic acid, 148 hypopbosphites, 183, 195, 213 lime, 210 the phosphates of iron, quinine and strychnine, 267 Tannate of antimony, 283 iron, 249 Tannic acid reagent, 249 Tar, 60 Tar-well, 60 Tartar emetic, 282 Tartaric acid. 96, 188 Tartrate, ammonio-ferric, 266 .— antimony and potassium, 282 — iron and ammonium, 266 potassium, 266 — potassium, 266 — potassium and sodium, 188 Tartrates, 188 Tests (see Analytical Reaction s). Thermometer, 234 Thiosulpbate of calcium, 198 sodium, 197 Tincture ferric acetate, 264 chloride, 255 — iodine, 83 Tooth-powder, 209 Triatomic, meaning of, 14 Tricalcic phosphate, 97, 98 Troches, chalk, 209 — iron, 264 — potassium chlorate, 188 — sodium bicarbonate, 198 Turpeth mineral, 243 Type-metal, 278 U. Ungueutum diachylon, 230 — hydrargyri, 236 ammoniati, 243 nitratis, 244 oxidi flavi, 241 rubri, 242 — iodi, 84 — plumbi carbonas, 232 iodidi, 231 — sulphuris, 91 — ziuci oxidi, 222 Univalent atoms, 14 Universe, estimated composition of, 22 V. Vacuum, 52 Valence, 14 Valerianate of ammonium, 204 — iron, 262 — sodium, 262 — zinc, 221 Valerianic acid, 204, 223 Valeric acid, 204, 222 Vallet's mass, 258 Vegetable kingdom, 55 Verdigris, 233 Vermilion, 234, 243 — Chinese, 243 Vertebrates, 208 Vienna green, 278 Vinum antimonii, 288 — ferri am arum, 268 citratis, 268 Vitriol, blue, 232 — green, 256 — oil of, 125 — white, 220 Volatile liniment, 202 — liquid hydrocarbons. 60 Volatility of metals, 160 Volumetric analysis, 198 W. Wade's Buchanan's method for hydrobromic acid, 246 Washed sulphur, 88, 89 detection of arsenic in, 89 Water, 34, 72 — ammonia, 201 stronger, 201 — atmospheric, 39, 40 — chemical properties of, 37 — clarification of turbid, 47 — composition of, 34 — contamination in, 44 — fresh, 40 — general properties of, 36 — hard, 41 action of, upon soap, 42 permanent, 41 temporary, 41 — impregnated with lead, 227 — Javelle's, 80 INDEX. 311 Water lead, 229 — lime, 210 — occurrence of, 36 — of crystallization, 38 — rain, 55 — relation to animal and vegeta- ble kingdom, 36 — salt, 40 — soda, 63 — transformations of, 34 Waters, aromatic, 213 — bitter, 192 — mineral, 43 acid, 43 alkaline, 43 borax, 43 chalybeate, 43 ferruginous, 43 lithia, 43 saline, 43 sparkling, 43 still, 43 sul phur, 43 — natural, constituents present in all, 36 — terrestrial, 39, 40 — well, contaminations in, 44, 45 detection of, 44, 45 purification of, 46, 47 White arsenic, 275 — lead, 231 — vitriol, 220 Wine of antimony, 283 ferric citrate, 268 iron, bitter, 268 Wines, effervescent, 64 Wood ashes, 177 — charcoal, 58 Wool fat, 178, 180 Writing of salts, 93 Y. Yellow iodide of mercury, 240 — mercuric oxide, 241 ointment, 241 subsulphate, 243 — prussiate of potash, 186 Z. Zinc acetate, 222 — bromide, 221 — carbonate, precipitated, 222 — chloride, 223 solution. 223 — granular, 220 — hydroxide, 222 — iodide, 223 — oxide, 222 ointment, 222 — phosphide, 223 — powdered, 220 — salts, 220 analytical reactions of, 220 impurities in, 221 — sulphate, 220 — sulphide, 220 — valerianate, 221 Zinci acetas, 222 — bromidum, 221 — carbonas precipitatus, 222 — chloridum, 223 — iodidum, 223 — oxidum, 222 — phosphidum, 223 — sulphas, 220 — valerianas, 321 ^ LIBRARY OF CONGRESS DDDE5a4fl37fl : .,>-:- ^:,li#Ul«M%>M»%H»^ WPfMn",'" 11