.v^^ &^?%i**' •f y?f N •i LIBRARY OF CONGRESS, ----- ®— *tw tev--_™ SBt ' :r ^ r •^Tiar.VN.* ▼ ^F- *^^ ^C9J. ft \. ^ty-** ™ 3K- ^^ ioj i-/ NtY^^g^^S gift »LVior v\i ^Wt^ ijfe /^ A' 'Aim * * Plate A. ^\ ^\ «s ,'"' s ----- '-? FIG. 9. Regular Cube. FIG. 1 1. Hexagonal Prism. FIG. 13. Quadratic Double Pyramid. FIG. 10. Regular Oetotaedron. FIG. 12. Double Hexahedral Pyramid. FIG. 14. Triclinic Prism. THE RED LINES REPRESENT THE AXES- Plate B. <; h FIG 15. FIG. 16. Axes connecting- opposite angles. Axes connecting opposite faces. / A . \ / \ \ / \ / FIG . 17. FIG. 18. Represents Figures 15 and 16 laid upon each Represents the truncation of the angles, other, c ausing intersection of faces, resulting from the intersection of and consequent truncation of faces. (Figure 17.) angles. (I "igurc 18 ) THE RED LINES REPRESENT AXES. [ONLY TWO OF THE THREE AXES ARE SHOWN.] THE PLANES OF THE FACES ARE REPRESENTED BY THE BLACK LINES. A COURSE Home Study for Pharmacists FIRST LESSONS STUDY OF PHARMACY OSCAR OLDBERG, P. D., Professor of Pharmacy and Director of the Pharmaceutical Laboratories in the Depart- ment of Pharmacy of Northwestern University (Illinois College of Phar- macy) ; Member of the Committee of Revision and Publication of the Phafmacopceia of the United States. WITH 150 ILLUSTRATIONS. 2^/3 U W CHICAGO: PUBLISHED BY THE APOTHECARIES' COMPANY. «3\ ftS Entered according to Act of Congress, in the year 1891, by OSCAR OLDBERG, In the Office of the Librarian of Congress, at Washington. ALL RIGHTS RESERVED. DONOHUE & HENNEBERRY, PRINTERS AND BINDERS, CHICAGO. PREFACE Out of at least 75,000 persons employed in the drug stores of the United States only a few thousand have enjoyed the advantages of systematic courses of special education offered by the colleges of pharmacy. But many thousands who can not, or think they can not, attend a college of pharmacy devote a por- tion of their time at home or in the store to such studies as they may think most useful to them in their professional work. Others, again, whose purpose it is to enter a college of phar- macy at the earliest opportunity, lind it highly advantageous to employ whatever time is at their disposal in suitable preliminary reading in order to so prepare themselves for the college course as to be able to derive the greatest benefit from it. The phar- macy laws, too, oblige many thousands to study at least enough to pass the State Board examinations. But whatever may be the motive that impels the prospective pharmacist to study, the measure of success he attains will depend upon what and how he studies. The book he reads must be that best adapted to his previous general and special education, and a text-book which may be unsurpassed when studied with the guidance and help of a teacher may be quite unsuitable for home study. Whether the road to the acquisition of knowledge be good, bad or indifferent, the student must travel it himself; no one else can do it for him. But the choice of a route is of scarcely less importance than the untiring pursuit of it. The best way to acquire a pharmaceutical education is to attend a good college of pharmacy No course of study at home can take the place of a good college with its experienced teachers and its invaluble laboratory practice; but home study Vi PREFACE. is of the highest importance to those who are prevented by cir- cumstances from entering college. The author has for several years past been called upon almost daily to recommend to prospective students of pharmacy some plan for systematic home study. Those who have asked such ad-vice were as a rule young men of fair common school education, but having little or no knowledge of physics, chemis- try, botany, or materia medica, or of the application of these branches of science to pharmacy. This book is the result of the author's effort to help his friends who thus call upon him. It is prepared expressly for prospective pharmacists and, therefore, adapted to their special wants It is a book of — FIRST LESSONS IN THE STUDY OF PHARMACY, and the Author has endeavored to treat the subject matter in a manner which will enable his readers to acquire a good knowl- edge of the essentials, and to utilize their opportunities of observation in the drug stores to facilitate their progress. The scope of the book is indicated in the table of contents. Throughout the book there are many cross-references to help the student. At the same time the author has not hesitated to repeat wherever repetition seemed likely to be more convenient to the reader than to refer him to other portions of the book. While Part I covers the whole field of Physics, only such portions as have a special interest to the student of pharmacy- are treated at any length. Part II covers theoretical chemistry quite sufficiently, and the experiments and examples given are such as the drug store affords. Chemical formulas, which are nearly always difficult to beginners, have been printed in two colors in the ten chap- ters devoted to the different classes of chemical compounds — the positive radical of the molecule in black, and the negative in red, so that the student can identify each at a glance. PREFACE. Vll Part III presents definitions of such general terms as medi- cines, drugs, chemicals, preparations, materia medica, pharma- cology, pharmacognosy, pharmacy, pharmacopoeia, pharmaco- dynamics, therapeutics, posology, etc. Chapter LXIII is devoted to a general review of the various classes of chemical constit- uents existing in plant drugs. In studying of the chemicals in Part II and of the crude drugs in Part III, the student should familiarize himself with their appearance as found in the store, and compare the descrip- tions given in the book with the articles described. A cabinet of such drugs as are not always found in drugstores except in a comminuted condition, will be found useful to the student. The symptoms of poisoning and customary antidotes are given under poisonous drugs. As the author believes that every drug clerk ought to have at least some idea of what is meant by such common therapeutic terms as alteratives, antipyretics, hypnotics, carminatives, dia- phoretics, etc., definitions of terms of this kind are given in Chapter LXXIV. The Dose Table which constitutes Chapter LXXV is a most extensive one, covering nearly 1,000 articles, and includes the new remedies, such as antipyrin, acetanilid, phenacetin, chloral- amid, urethan, hypnone, the rarer alkaloids, etc. The author is indebted to many of the standard text-books on physics, chemistry, materia medica and pharmacy — foreign and American — for his materials. To the student I wish to say that the mere memorization of facts and theories, however valuable these may be when prop- erly used, should by no means be your main object. It should be your constant aim to clearly imder stand what you read, to develop your faculties of observation and reasoning, and to be able to rightly use what you learn. Only by using it and adding to it can you make it your own. THE AUTHOR. Chicago, June, 1891. TABLE OF CONTENTS. PAGES. Preface v-vii PART I. ELEMENTS OF PHARMACEUTICAL PHYSICS. CHAPTER I. Matter — Definition — Properties i- 8 CHAPTER II. Forces and Phenomena — Attraction and Repulsion — Gravitation — Weight — Specific Weight — Cohesion — Adhesion — Atomic Attraction. 8- 14 CHAPTER III. Phenomena Dependent upon Cohesion — States of Aggregation — Solids — Liquids — Gases — Fluids — Vapors - 14-18 CHAPTER IV. Crystalline Bodies — Crystals — Crystallizable Substances — Amorphous Substances 18- 21 CHAPTER V. How Crystals are formed — Axes — Faces — Edges — Angles — Cleavage — Cubes — Prisms — Pyramids — How Crystals are Produced 22- 25 CHAPTER VI. Water of Crystallization— Anhydrous and Hydrous Crystals 25- 28 CHAPTER VII.' Classification of Crystals — Crystallography — The Six Systems 2S- 35 CFMPTER VIII. Adhesion — Adhesiveness — Mixtures — Miscibility 35- 37 CHAPTER IX. Capillarity and Osmosis — Capillary attraction — Diffusion of liquids — Osmosis — Dialvsis 37- 43 CHAPTER X. Solution — Solubility — Simple and Chemical Solution — Solvents 44- 47 CHAPTER XI. Motion — Laws of Motion — Momentum — Center of Gravity — Equilibrium — Stability — Velocity — Pendulum — Energy 47- 53 CHAPTER XII. Work and Machines — Units of Work — Levers — Balance — Pulleys — Inclined Plane— Wedge— Screw — Friction 54- 58 CHAPTER XIII. Hydrodynamics— Pressure upon Liquids— Hydraulic Press — Law of Archimedes — Hydrometers 58- 66 ix X CONTENTS. CHAPTER XIV. Pneumatics — Tension of Gases — Mariotte's Law — Atmospheric Pressure — Barometer — Siphon 66- 73 CHAPTER XV. Heat — Definition — Active and Latent Heat — Temperature — Sources.. 73- 76 CHAPTER XVI. Thermometry — Mercurial Thermometers — Other Thermometers 77- 79 CHAPTER XVII. Absolute and Specific Heat — Absolute Temperature — Thermal Units 80- 82 CHAPTER XVIII. Distribution of Heat — Conduction— Connection — Ventilation — Radiation — Transmission — Absorption 82- 86 CHAPTER XIX. Expansion of Bodies by Heat — Force of Expansion and Contraction — Coefficients of Expansion — Expansion of Water 86- 89 CHAPTER XX. Relation of Temperature to the three states of Aggregation — Action of Heat on Solids — Fusion — Sublimation — Fixed and Volatile Sub- stances — Evaporation — Boiling — Distillation 90- 97 CHAPTER XXI Temperature and Humidity of the Air 97- 98 CHAPTER XXII Light — Transparent, Translucent and Opaque Bodies — Luminous Rays — Sources of Light — White Light — The Prismatic Colors 98-102 CHAPTER XXIII. Electricity — Static and Galvanic Electricity — Magnetism — Induction — Currents— Chemical Effects 102-106 PART II. ELEMENTS OF CHEMISTRY. CHAPTER XXIV. Masses, Molecules and Atoms — Introductory — Mixed Matter — Single Substances — Atoms — Molecules — Masses — Elements — Compounds — — Physical and Chemical Properties — Physics and Chemistry. . . .109-118 CHAPTER XXV. Chemical Phenomena — Relative Stability of Molecules — Reactions. . .118-123 CHAPTER XXVI. Chemism — Intensity, Quality and Quantity — Factors and Products of Chemical Reactions — Synthesis and Analysis — Decomposition — Con- ditions favorable to Chemical Reaction — Relation of Heat to Chem- ism — Electricity — Status Nascendi — Dry and Wet Processes — Pre- disposing Affinity 123-131 CHAPTER XXVII. The Law of Opposites in Chemistry — Acids and Alkalies — Electrolysis and Electro-chemical Theory — Electro-Chemical Series 131-138 CONTENTS. Xi. CHAPTER XXVIII. Fixed Combining Proportions and the Atomic Theory— Atomic Weights — Dalton's Law — Law of Dulong and Petit — Specific and Atomic Heat — Molecular Heat — Gay-Lussac's Law of Simple Combining Proportions by Volume — Avogadro's Law 139-149 CHAPTER XXIX. Valence — Artiads and Perissads— Bonds — Variable Valence. . . ... .150-158 CHAPTER XXX. Chemical Notation — Symbols — Formulas — Chemical Equations 15S-163 CHAPTER XXXI. The Elements — General Review 163-170 CHAPTER XXXII. Oxygen, Hydrogen and Sulphur 171-179 CHAPTER XXXIII. The Halogens — Chlorine — Bromine — Iodine 179-1S2 :hapter xxxiv. The Nitrogen Group and Boron 182-190 CHAPTER XXXV. The Carbon Group . . 191-195 CHAPTER XXXVI. Summary of Non-Metallic Elements 195 CHAPTER XXXVII. The Light Met als and Ammonium 196-204. CHAPTER XXXVIII. The Heavy Metals 204-21 1 CHAPTER XXXIX. Summary of Metallic Elements 211-213 CHAPTER XL. Compound Radicals — Negative and Positive Radicals 213-220 CHAPTER XLI. Tables of Radicals, Simple and Compound — Positive and Negative. . . 220-223 CHAPTER XLII Compound Molecules — Atomicity of Molecules — Direct Union — Chains — Linkage — Molecular Formulas 224-234 CHAPTER XLIII. Classes of Compounds— Inorganic — Organic 234-235 CHAPTER XLIV Oxides and Sulphides 235-239 CHAPTER XLV. Haloids — Chlorites — Bromides — Iodides — Cyanides 240-247 CHAPTER XLVL Bases — Hydroxides — Base-residues 247-250 CHAPTER XLVII. Acids — Hydroxyl Acids — Hydrogen Acids — Reactions between Bases and Acids — Action of Acids on Metals 250-255 XI 1 CONTENTS. CHAPTER XLVIII. Salts — Normal and Acid Salts — Basic Salts — Oxy-salts and Haloids. .256-259 CHAPTER XLIX. Nitrates Chlorates and Hypochlorites 259-26 CHAPTER L. Sulphates and Sulphites — Thiosulphates ... 262-265 CHAPTER LI. Phosphates — Ortho-, Meta-, and Pyro-Phosphates — Hypophosphites 265-268 CHAPTER LII. Carbonates — Borates — Silicates — Arsenates — Arsenites 261-270 CHAPTER LIII. Metallic Salts with the Organic Acids — Acetates — Valerates — Lactates — Oleates — Oxalates — Tartrates — Citrates — Salicylates, etc 271-276 CHAPTER LIV. Hydrocarbons — Methane Series — Other Series — Hydrocarbon Radicals 276 280 CHAPTER LV. Other Organic Compounds — Alcohols — Aldehyds — Ketones — Acids — Ethers — Ethereal Salts — Carbohydrates — Glucosides — Alkaloids . . 2S0-289 CHAPTER LVI. Chemical Nomenclature — Rules — Terminal syllables— Prefixes 289-295 CHAPTER LVII. Laws Governing the Direction and Completeness of Chemical Reac- tions — Laws of Malaguti and Berthollet 296-300 CHAPTER LVIII. Oxidation and Reduction — Combustion — Oxidizing Agents — Reducing Agents 301-302 CHAPTER LIX. Neutralization and Saturation— Test-papers — Solution of Metals in Acids 303-306 CHAPTER LX. Precipitation — Insoluble Compounds 306-313 PART III. MATERIA MEDICA. CHAPTER LXI. Introductory — Definitions of Drugs and Preparations — Materia Medica, Pharmacology, Pharmacognosy — Official and Officinal Medicines — Pharmacopoeias — Pharmacy and Pharmacodynamics — Therapeutics and Posology 31 7-328 CHAPTER LXII. Plant Drugs — Collection, Cleaning, Garbling, Drying 328-332 CHAPTER LXIII. What Plant Drugs Contain— Proximate Principles — Cellulose — Starch — Gum— Pectin — Sugar— Albuminoids — Fixed Oils — Organic Acids — Volatile Oils— Resins — Balsams — Oleoresins — Gum-Resins — Neutral Principles — Tannin— Glucosides — Alkaloids 332-345 contexts. xiii CHAPTER LXIV. Roots, Rhizomes, Conns and Bulbs 345-354 CHAPTER LXV. Woods Barks and Nutgall 354-359 CHAPTER LXVI. Herbs, Flowers and Leaves 360-367 CHAPTER LXVII. Fruits and Seeds 367-373 CHAPTER LXVIII. Miscellaneous Crude Plant Drugs 374-377 CHAPTER LXIX. Starches, Gums and Saccharine Drugs 378-379 CHAPTER LXX. Gum-Resins, Resins and Oleo-resins . . 379-3S4 CHAPTER LXXI. Fats and Fixed Oils 3S5-386 CHAPTER LXXII. Volatile Oils and Camphors 387-391 CHAPTER LXXIII. Animal Drugs 391-392 CHAPTER LXXIV. Therapeutic Classification of Medicines — Definitions 392-39S CHAPTER LXXV. Dose Table of nearly 1,000 articles, including new medicines 399-418 PART IV. PHARMACY. CHAPTER LXXVI. Heating Apparatus — Fuel-Generation and Applications of Heat A or Phar- maceutical Purposes — Sand-bath, Water-bath, and other Baths — Dry D rocesses requiring Heat 421-430 CHAPTER LXXVII. Comminution — Apparatus and Implements — Mills — Mortars and Pestles — Contusion — Trituration — Powders — Sifting 430-437 CHAPTER LXXVIII Solution in Pharmacy — How made — Solvents — Saturated and Super- saturated Solutions — Partial Solution — Menstrua 437-443 CHAPTER LXXIX. Filtration and other Methods of Clarifying Liquids — Filters — Filter fun- nels — Colation — Decantation — Clarification — Sediments 443-450 CHAPTER LXXX. Evaporation and Distillation — Ebullition — Boiling vessels — Evaporat- ing vessels — Stills — Retorts — Condensers — Receivers — Fractional Distillation — Generation and Solution of Gases — Woulf's bottles.. 45 1-460 XIV CONTEXTS. CHAPTER LXXXI. Crystallization and Precipitation — Crystallizers — Size of Crystals — Retarded crystallization — Mother-liquor — Granulation — Precipitation — Precipitating vessels 460-466 CHAPTER LXXXII. Methods of Extraction of Soluble Matters from Plant Drugs — Extracts and Extractive — Apotheme — Maceration — Digestion — Infu- sion— Coction — Displacement — Percolation — Percolators 467-475 CHAPTER LXXXIII. Pharmaceutical Preparations — General Review — Pharmacy of Inorganic and Organic Drugs Compared 476-477 CHAPTER LXXXIV. Dry and semi-solid preparations for Internal Use not made by Extrac- tion — Species — Powders — Confections — Masses — Troches — Pills.. 477-479 CHAPTER LXXXV. Liquid Preparations not made by Extraction — Solutions — Waters — Mucilages — Glycerites — Syrups — Spirits 4S0-4S3 CHAPTER LXXXVI. Liquid Preparations made by Extraction — Infusions — Decoctions — Vinegars — Tinctures — Wines — Fluid Extracts 4S4-4S7 CHAPTER LXXXVII. Solid Preparations for Internal Use made by Extraction — Extracts — Abstracts — Oleoresins — Resins 487-490 CHAPTER LXXXVIII. Preparations for External Use— Ointments — Cerates— Plasters — Oleates — Suppositories — Gargles — Lotions — Injections — Collodions — Lini- ments 490-494 CHAPTER LXXXIX. The Latinity of Pharmaceutical Nomenclature — Latin Declensions — Nouns, Adjectives and Numerals 494-502 CHAPTER XC Weights and Measures — The Metric System — Apothecaries' Weights and Measures — Avoirdupois Weight — Equivalents 503-505 Index 507 PART I. PHYSICS. PART I. PHYSICS, CHAPTER I. MATTER. 1. Physical Bodies are the things of external Nature which consist of matter (3). Any portion of matter perceptible to our bodily senses is a body. A body is an aggregation of any number of molecules (16 and 17). We can also say that a body is any mass of matter without reference to quantity. Ex. — Any piece of wood, stone or coal, any quantity of water, air or oil, a lump of sugar, a crystal of salt, any animal or plant, the paper upon which this book is printed, the printer's ink used in it, and the book itself as a mate- rial thing — all these are bodies. [The term " body " is also often used in the same sense as the term " sub- stance " (18); thus we find carbon described as a "fixed body" (83), while iodine is referred to as a " volatile body " (83). On the other hand, the term " mass " is commonly employed to designate an aggregation of any number of molecules (16) without regard to quantity. This use of the term mass is very convenient, but conflicts with the universal use of that term as defined in para- graph 7. In this book the term body will be used only to designate any body of matter without regard to the actual qttantity (mass) of matter contained in it; and the term mass will be used in the sense fixed by its definition in par. 7.] 2. Mathematical Bodies represent form and extension, inclosing empty space, thus differing radically from physical bodies which contain or consist of matter (3). We can think of and represent mathematical bodies, such as cubes, spheres, cones, cylinders, etc., without any reference to matter, because they have definite bounds although void of matter. 2 PHYSICS. 3. Matter is that which occupies space or possesses exten- sion. By matter we also understand that which possesses weight (40) without regard to the amount of space which it occu- pies. 4. Whatever occupies space is matter, and nothing can be matter which does not occupy space. 5. No two bodies can occupy the same space at the same time, for every particle of matter occupies its own space, to the •exclusion of every other particle of matter, This property of matter is called Impenetrability (26). Ex. — An egg can not be put in a tumbler previously filled with water without causing the water to overflow, because the egg necessarily displaces its own volume of water from the space occupied by it. Air is matter. It, therefore, occupies space. When we speak of an " empty " bottle and an " empty " tumbler, and say that there is " nothing " in them, we ignore the fact that they contain air. Experimentally, you may prove this by inverting the tumbler and pressing it downward in water; if there were nothing in it, the water would fill it, but the water will not fill it because the air in the tumbler occupies the space and the water can not occupy it at the same time. 6. Since by Matter we also understand the weighable with- out regard to its extension, it follows that whatever has weight (40) is matter, and that whatever has no weight can not be mat- ter. 7. Mass. — Any amount of matter, regardless of the space it occupies, is called Mass, Since matter is that which is weighable, its mass is ordinarily measured by weight (40). [But the mass of a particular body is a positive quantity, while its weight varies with its distance from the earth's surface (38).] The Mass of a body, then, is the actual quantity of matter con- tained in that body, and mass has nothing to do with size or bulk. 8. All material bodies have volume (9) and weight, as indi- cated in paragraphs 4 and 6. 9. Volume. — The volume of a body is the space occupied by it. All bodies have extension in all directions, and the measure of this extension is called volume. PHYSICS. 3 Thus the length, breadth and thickness of a cubical crystal (130) indicate its extension and determine its volume. Space devoid of matter is called vacuum. 10. The relation of mass to volume is called Density. Density expresses the relative amount of matter contained in a given volume. It is evident that bodies having the same volume may nevertheless have different masses, and that bodies having the same mass may have different volumes. Hence the necessity of the term " density " to express the relation of the mass (7) to the volume (9). 11. Of two bodies having the same volume but not the same mass, the one containing the greater amount of matter, or hav- ing the greater mass (7), has, therefore, the greater density (10). In other words, the greater the quantity of matter contained in a given volume of a body, the greater will be the density of that body. Ex. — Brass and bees-wax are bodies. Let us compare equal volumes of these bodies. A cul5ic inch of brass contains a greater amount of matter, or has a greater mass, than a cubic inch of wax; the density of brass is, there- fore, greater than the density of wax. Since matter is that which has weight (3) and mass is accordingly meas- urable by weight (7), a cubic inch of brass must weigh more than a cubic inch of wax if the brass is denser. Verify this by placing a piece of brass on one pan of the balance, and a piece of wax of the same size on the opposite pan; you will find that the pan loaded with the brass piece goes down, and the other up. If you now add as much wax to that already placed on the pan as may be necessary to counterbalance the brass, the bulk of the wax will be several times as great as that of the brass when their weight is equal. 12. Of two bodies having the same mass, each containing an equal amount of matter, but not of the same volume, the one having the smaller volume has, therefore, of necessity the greater density. Ex. — A pound of lead and a pound of lard have the same mass, because they have the same weight (40), but the pound of lead occupies much less space (or has a less volume) than the pound of lard; therefore, the density of lead is greater than the density of lard. 13. When two or more bodies are of like density, their rela- tive masses correspond to their relative volumes. 4 PHYSICS. Ex. — Castor Oil and Copaiba have the same density; therefore, it follows that one pound of castor oil has the same volume as one pound of copaiba; it also follows, that if one bottleful of castor oil weighs three times as much as another bottleful of copaiba, the bottle containing the castor oil must have three times the capacity of the one containing the copaiba, and the volume of the oil must be three times as great as the volume of the copaiba; and six- teen pints of copaiba must weigh sixteen times as much as one pint of cas- tor oil. 14. Having now learnt what is meant by each of the terms body (1), matter (3), mass (7), volume (9), and density (10), let us next consider some of the general properties of matter (or the " universal properties of matter "). We have already seen (3) that all matter occupies space and has weight. But volume and weight are not properties of matter, for we can think of space without reference to matter, and weight is an effect produced upon matter by a cause exter- nal to and distinct from it (40). One of the "general properties of matter " # has been noted, however, namely its impenetrability (5). As we will presently find (17) there are very numerous forms or different kinds of matter, each particular kind possessing its own specific properties; but all of these different kinds of matter possess certain properties in common, and the properties which are common to all matter are called the general properties of matter. Among them are: Divisibility (15), Porosity (25), Impenetra- bility (26), Indestructibility (27), Compressibility (29), Expansi- bility (29), Elasticity (30), and Inertia (31). 15. Divisibility. — We know from experience that all larger bodies can be divided into smaller bodies. Large pieces of stone upon the public road are ground up into fine dust. It is impracticable to determine by the aid of our physical senses, the extent of this divisibility of bodies, but it is evident from the fact that matter occupies space, and is impenetrable, that, however small the individual particles may be made, mere mechanical division can effect no other change but that of reduc- ing the size of each portion. In order, however, to account for the changes and conditions PHYSICS. 5 of matter which have been observed, it is assumed that all mat- ter consists of particles of definite size called molecules (16). The possible physical divisibility of matter, therefore, extends to its molecule, but no further. 16. Molecules, then, are the smallest particles of any given kind of matter that can subsist alone, or the smallest particles into which any kind of matter can be divided without losing its identity or without being changed into some new kind or kinds ot matter. 17. Kinds of Matter. — There are numerous kinds of mat- ter. Indeed, the distinct kinds of matter already known are countless, and new kinds are daily discovered. It follows from what was stated in paragraph 16 that there are as many kinds of matter as there are different kinds of molecules, and vice versa. 18. Substance. — The word substance will be used to desig- nate a particular kind of matter. 10. From what has been said (16) you are to infer that molecules are not absolutely indivisible; for, while it is true that whenever the molecule of any substance is divided, that sub- stance ceases* to exist as to its kind, being converted into some other substance or substances, all molecules may be divided into still smaller particles called atoms (20), which are, with rare exceptions, incapable of subsisting separately or in a free state, but which unite with each other to form molecules and are capa- ble of being transferred from one molecule to another. 20. Atoms are the smallest particles of matter that can take part in the formation of molecules. They are indivisible, phys- ically and chemically (22). The reasons for supposing that matter is not divisible without limit, but that all matter consists of indivisible particles (called atoms) will be stated further on (577580). 21. Atoms unite with other atoms either of the same kind or of different kinds, forming molecules. 22. When molecules are divided, disrupted or decomposed into their con- stituent atoms, these atoms rearrange themselves immediately to form new molecules. The division of the molecule is not mere mechanical division, or a physical division, but it is chemical decomposition. 6 PHYSICS. 23. All changes which take place within the molecule, or which involve the division of molecules, belong to the domain of Chemistry. 24. The subject of the divisibility of matter is so important as to justify a recapitulation here. With regard to its division, matter may be considered in three distinct conditions; namely, its Molar condition, its Molecular condition, and its Atomic condition. 1. Molar matter, or the material bodies (" masses of mat- ter") perceptible to our senses. Bodies or masses of matter (1) are made up of molecules held together by molecular attraction. 2. Molecular matter, or molecules (16) composed of atoms held together by atomic attraction. The molecule is the small- est particle of any kind of matter that can subsist, as it can not be divided without being transformed into some other kind or kinds of matter. j. Atomic matter, or atoms (20) of matter, or particles of matter which can not be divided by any means. Atoms unite with each other chemically to form molecules, and can pass from one molecule to another, but are incapable of separate subsist- ence. 25. Porosity. — Pores are the extremely minute spaces between the molecules of bodies. All bodies are pcrous. This property is accounted for by the hypothesis that the molecules are not in actual contact. Distinction should be made between the invisible physical pores, which are above referred to, and the sensible pores, which are the actual cavities observed in porous substances like pumice stone, filter paper, unglazed earth- enware, etc. 26. We may now refer once more to the impenetrability of matter. Since the molecules of a body are not in actual contact with each other, tw T o different substances may be inti- mately mixed with each other, the molecules of one occupying a portion of the space between the molecules of the other, as in a solution of sugar in water, but the molecules can not penetrate each other (5). 27. Indestructibility. — Matter can not be annihilated. It PHYSICS. 7 can be changed as to its kind but not as to its amount. The amount of matter in the universe can neither be added to nor diminished. It is uncreatable as well as indestructible (490). 28. Contraction and Expansion of Volume.— By reason of its porosity (25) matter may be made to occupy more or less space without change of mass. Not being in actual contact with each other, the molecules may be brought nearer to each other by compression of the body or by a reduction of its tem- perature ; or they may be separated further from each other by the withdrawal of pressure or by the aid of heat. 20. By the Compressibility of matter we understand that masses of matter can be compressed or forced to occupy less space without diminution of mass. By Expansibility is meant the opposite of compressibility. Bodies can be made to occupy more space without any increase of their mass. 30. Elasticity is the property by virtue of which a body which has been compressed or expanded by some force exter- nal to itself resumes its original volume. 31. Inertia is a term used to express the recognized ina- bility of matter to move without the impulse of some force external to itself and its inability to stop of its own accord when once put in motion. Matter at rest must remain at rest until put in motion by some force, and matter in motion must continue in motion until its motion is arrested by some force. 32. Among the specific (or characteristic) properties of mat- ter are: Hardness, by which some substances more or less strongly resist superficial impression or scratching; Tenacity, by which some kinds of matter resist more strongly than others an effort to pull their bodies apart; Brittleness, or the property of being easily crushed; Malleability, or the property by virtue of which some metals may be rolled or hammered into plates or sheets, and Ductility, which renders it possible to draw certain metals into wire. The " specific properties" enumerated and defined in the 8 FHYSICS. preceding lines depend chiefly upon the various states and degrees of cohesion and adhesion. Other characteristic or specific properties of different kinds of matter are such as peculiar form, color, odor, taste, solubilities, melting point, boiling point, molecular weight, relative stabil- ity of their molecules, etc. CHAPTER II. FORCES AND PHENOMENA. 33. Phenomena. — The changes occurring in the form, condition, and properties of matter are called phenomena. They are caused by forces (34 to 36) operating in accordance with fixed laws of nature. 34. Force is whatever produces, changes, or arrests motion (59). It manifests itself under various forms. Like matter it is uncreatableand indestructible. It can neither be added to nor diminished. 35. Attraction and Repulsion. — All particles of matter pos- sess a tendency to attract and to repel other particles of matter. All motion (59) is the result of these pushes or pulls, which are caused by the attractive and repellant forces. Attraction and repul- sion co-exist, and the resultant motions and conditions of matter vary as the one or the other predominates. 36. All attraction and repulsion between different portions of matter are mutual. Thus if the body A attracts the body B to itself, A is also attracted by B, and if one particle of matter repels another the repulsion is reciprocated. 37. Attraction is called molar attraction, or "mass attrac- tion " when it operates between bodies of matter, or between masses of molecules. The attraction between molecules is called molecular attraction. The attraction between atoms is called atomic attraction, chem- ical attraction, or chemical affinity. PHYSICS. 9 GRAVITATION. 38. Molar attraction affects all bodies at all distances. Thus all bodies in the universe are mutually attracted to and by each other. The relative measure of this attractive force is in direct ratio to the masses of the bodies, and at the same time in inverse proportion to the squares of their distances from each other. The greater the mass of a body, the greater will be the result of its attracting force exerted upon other bodies, and the greater also the force with which it is itself attracted toward larger bodies. The further apart two bodies are from each other, the weaker the attraction between them. This universal attraction which operates between all bodies is called Gravitation. The laws which govern this mass attraction and its relative force, direction, and results, are called the laws of gravitation. 39. The planets and all other bodies in the universe are held in their positions by gravitation. Gravitation is operative between the earth and any one of the heavenly bodies, between the heavenly bodies respectively, between all bodies upon the earth's surface, or between any two bodies. 40. Weight. — The mass of the terrestrial globe being greater than that of any other body in its atmosphere we ordi- narily take notice only of that attraction which the earth exerts upon all bodies upon or near its surface. The ruling power by which the earth attracts toward its cen- ter other bodies of lesser mass is called weight. Thus it is the pressure which a terrestrial body exerts upon a horizontal plane which prevents it from falling. It may also be said to be the force required to neutralize the earth's attraction upon a body on or near its surface. 41. Gravity. — A body whose gravitation is exactly equal in all directions, remains in the same position though it may be sus- pended in space. Such a body, in relation to other bodies, has gravity but not weight. Sometimes " gravity " is defined as "the attraction between the earth and bodies, upon or near its surface;" thus, that which we have called IO PHYSICS. "weight" in par. 40; and when gravity is thus denned, the term weight is defined as " the measure of gravity." 42. Weight is considered in two different ways — 1. As abso- lute weight (43), which is weight without reference to volume; and 2. Specific weight (47), which is the ratio of weight to volume. 43. Absolute weight is expressed in units of fixed value which are chosen as standards of comparison. The British standard of weight is the avoirdupois pound, which is made of plat- inum and copies of which are used for weighing things; the standard of weight used in science, and in the greater part of the civilized world for all other purposes, is the Gram, which rep- resents the weight of one Cubic-centimeter of water. 44. True weight is the weight of a body in a vacuum (9). 45. Apparent weight is the weight of a body in air or in any other fluid (80). 46. When we say that one piece of iron is heavier than another piece of iron, that a pound is lighter than a kilogram, or that a cubic inch of water weighs more than a cubic-centi- meter of the same liquid, we are comparing their absolute weights, and the differences are accounted for by the fact that their volumes differ. In other words absolute weight may be determined and expressed without reference to volume. 47. Specific Weight is the relation of the weight of a body to its volume. It is nearly synonymous with density (10), for the specific weight of a body must necessarily be in direct ratio to the mass as compared with the volume, and we know that the greater the mass of a terrestrial body the greater will be the gravitating force by which it is drawn towards the center of the earth (40). Specific weight may also be said to be the relative gravitating force o one substance as compared with that of a like volume of some other substance. 48. When we speak of iron as being heavier than chalk, or say that ether is lighter than chloroform, it is always under- stood that the comparison refers to equal volumes, and the weights referred to in this connection are, therefore, the specific weights proper to these substances respectively. PHYSICS. II When equal volumes of any two or more substances are weighed, we gen- erally find that their weights differ. That is because their densities differ. And the differences in weight caused by differences in density are indicated by the specific weights. 49. In order to express the specific weights of substances some one substance must be chosen as the standard of compari- son. Thus the standard of comparison adopted for all solids and liquids is water, while the standard of comparison now used in expressing the specific weight of gases is hydrogen. [Formerly the standard unit for gases was the specific weight of air; but, for reasons which you will better appreciate as you learn chemistry, it is far more convenient as well as scientific to adopt the hydrogen unit.] 50. Thus the specific weight of water is called 1, and as the specific weights of all solids and liquids are expressed in water units it follows that any substance which is only half as heavy as water has the sp. w. 0.500 and any substance twice as heavy as water has the sp. w. 2. As a cubic inch of silver is 10^ times as heavy as a cubic inch of water, the sp. w. of silver is 10.500 (\vater=i); if a cubic foot of glass weighs three times as much as a cubic foot of water, the sp. w. of that glass is 3.000; since the weight of any given volume of mercury is 13.596 times the weight of the same volume of water, the sp. w. of mercury is 13.596 (water=i). Ice weighs only 0.930 times as much as the same volume of water; therefore, the sp. w. of ice is 0.930 (water=i.) 51. In stating the specific weights of gases, we call the sp. w. of hydrogen 1, and the specific weights of all other gases are expressed in hydrogen units. Thus Oxygen has the sp. w. 16 (H=i), for a liter of oxygen weighs sixteen times as much as a liter of hydrogen; but chlorine is heavier than oxygen, any given volume of chlorine being 35.45 times as heavy as an equal volume of hydrogen, the sp. w. of chlorine being, therefore, 35.450 (H=i). 52. Compared with each other the specific weights of the substances used as standards of comparison for other substances are aboutas follows at the temperature of 15 C. (59 F.) Water 1 (water=i), or 11,400 (H.^=i), or 815 (Air=i). Hydrogen 1 12 PHYSICS. (H.= i), or 0.0691 (Air=i), or 0.000085 (water=i). Air i(Air=i), or 14.44 (H.=i), or 0.00122 (water— 1). Fig. i. Fig. 2. Fig. 1 Represents the volume of one grain of air. Fig. 2. the volume of one grain of water. Thus water is about 11,400 times as heavy as hydrogen, and 815 times as heavy as air (see figures 1 and 2); hydrogen is 0.0691 times as heavy as air, and 0.000085 times as heavy as water; air is 14.44 times as heavy as hydrogen, and o 00122 times as heavy as water. 53. The expression " specific gravity " is generally used instead of the more correct expression specific weight. As com- monly employed both expressions mean precisely the same thing. MOLECULAR ATTRACTION. 54. Molecular attraction is of two kinds — Cohesion and Adhesion. 55. Cohesion is that molecular attraction which operates between the like molecules of a chemically homogeneous body. 56. Adhesion is the molecular attraction which holds together the unlike molecules of mixtures, or which operates between the molecules of two or more different substances. 57. Atomic Attraction governs the relative stability of different kinds of matter. It causes the change of particular kinds of matter into other kinds when the conditions are favora- ble. It renders possible the assimilation of food by plants and PHYSICS. 13 animals. Decay and decomposition, as well as the formation of new substances out of the debris, are the results of atomic attraction. It will be considered further on more fully under the head of chemistry. 58. Energy, which is the power to do work, or to overcome resistance, is the product of force (34). A force does work when it produces or arrests motion (59). 59. Motion is a change of place. We are to distinguish between molar, molecular and atomic motion. 60. Molar Motion, or " mass motion," and molar force pertain to bodies of matter. Dynamics (197) treats of the states and motions of matter in its molar con- dition, and of the relations and results of molar attraction and repulsion. Dynamics is a more comprehensive term than the expression "mechanical science " which treats of the application of dynamics to the accomplishment of useful work, the construction of machines to that end, etc. 61. Molecular Motion, or the molecules within the body or " mass," is distinct from both molar and atomic motion. The mass may be at rest while its molecules are constantly in motion. The motion of the molecule is distinct from the motion cf the atoms of which it consists. Molecular motion never ceases. 62. But while the whole body may move independently of the motions of its molecules, the several modes of molecular motion involve the whole mass, all of its molecules being affected. Molecular motion is vibratory — not progressive. 63. Among the modes of molecular motion are Sound, Heat (305), Light (412), and Electricity (430). 64. Atomic Motion, or the motion of the atoms (20), within each molecule (16), is doubtless as never-ceasing as molecular motion (61), although its existence has not been demonstrated In chemical reaction (493), the atoms must be extremely active. But we must defer the consideration of atomic attraction 14 PHYSICS. and repulsion, and the resultant atomic activity until we reach the subject of Chemistry. 65. Recapitulation. — Having now learned that the various modes of molecular motion, or manifestations of energy, are what we call sound, heat, light and electricity, we may close this chapter by the statement that these several different forms of motion are interconvertible. 66. Correlation of Energy.— Energy of any kind can be changed into energy of any other kind.. Thus, the different forces are only different forms of one universal Energy and mutually interchangeable. 67. Conservation of Energy. — Whenever any form of energy disappears, its exact equivalent in another form takes its place, so that the total sum of energy in the Universe remains unchanged. CHAPTER III. PHENOMENA DEPENDENT UPON COHESION. 68. The three states of aggregation of matter are the so/id, the liquid, and the gaseous state. 69. Solids are bodies in which the molecules are held together so firmly by cohesion (55) that they retain their form with- out support, under ordinary conditions (of pressure and tem- perature), and can be changed as to their form only by external violence, or by the influence of heat (375), or by solution (183). Ex. — All metals, except mercury, are solids. Rocks, trees, ice, butter, paper, cobweb, pieces, panicles of powder, dust — all these are solid bodies. 70. According to their consistence the solids are hard, soft, tough, brit- tle, elastic, rigid, flexible, malleable, ductile, etc. Several of these terms will be understood by reference to par. 32, while others explain themselves or may be found in any dictionary. PHYSICS. J 5 FORMS OF SOLID BODIES. 71. The greater number of solid bodies do not exhibit any- definite or regular form. Yet many organic substances (454), formed in plants or animals, show a tendency toward the forma- tion of more or less globular masses, and many inorganic sub- stances together with a large number of products of the chemist's laboratory, have well defined angular geometric forms, called cry 'stals (84). Figure 3. Figure 4. Figur j 5. [See crystalloids and colloids, par. 179.] 72. Substances occurring in crystals or crystalline masses are called crystallic, or crystalline (89) substances; all others are said to be amorphous (96), or formless. 73. Solids which are not altered by exposure are said to be permanent in the air. Those that absorb moisture from the air are hygroscopic, and if they take up so much moisture as to become quite wet, they are deliquescent. Crystallic and crystalline substances, when they give up their water of crystallization (121) on exposure to the air, thereby losing their crystalline form, are called efflorescent (123). Ex. — Gold, corrosive sublimate, cream of tartar, are " permanent in the air." Squill and gentian are "hygroscopic." Chloride of iron, potassium carbonate and zinc chloride are " deliques- Copperas, washing soda and Glauber's salt "effloresce." l6 PHYSICS. 74. Liquids have apparently no form of their own. In very small particles of liquids the cohesion overcomes gravity (provided adhesion between the liquid and other sub- stances do not interfere), so that the molecules, attracted toward the center of the mass, form spheres or spheroids, as may be seen in drops of dew, globules of mercury or drops of water rolling upon a surface dusted with lycopodium. Drops of olive oil will float about in a mixture of six cubic centimeters of alco- hol and four cubic centimeters of water, the drops of oil exhib- iting a perfectly spherical form. But when the body of liquid is larger, the force of cohesion is overcome by the force of gravity which tends to bring the molecules to the same level, and the liquid then assumes the shape of the vessel in which it is contained. When the support around the body of liquid is taken away, the liquid, impelled by gravitation, spreads outward and downward over the solids in its way. Water is a most familiar and perfect example of liquids. Alcohol, ether, chloroform, glycerin, fixed oils, syrups, tinct- ures, sulphuric acid and mercury are other examples of liquids. 75. Liquids are not easily compressed. To compress their volume requires very great force; the compression is but slight, and on removal of the pressure they immediately resume their original volume, being perfectly elastic. The enormous pressure necessary to compress water in any appreciable degree warrants the conclusion that liquids are prac- tically incompressible. 76. Liquids maybe viscid, like tar, honey, or thick mucilage, or they may be mobile, like chloroform; they may be heavy, like sulphuric acid, or light, like ether. Honey, tolu, storax, oleate of mercury and many other substances are frequently in such a condition that it is not easily determined whether they ought to be called solids or liquids. Very thick, sluggish liquids and solids approaching a liquid condition — in other words, substances partaking of the consist- ence of both solids and liquids — are called semi-solids, or semi- fluids. PHYSICS. 17 They are simply substances whose melting points or con- gealing points (376) are the common temperatures of the air or of our warehouses, shops and work-rooms. 77. Gases are aeriform bodies, or bodies like air, which, being neither solids nor liquids, do not retain a definite shape, or outline of their mass, when put in an open vessel, as the cohesion between their molecules is nullified (81). Gases, instead of being governed by cohesion (55), resist compression (29) of volume by a certain degree of force called tension (279). Their molecules, therefore, seem to be governed by repulsion instead of by attraction (35). Accordingly, they diffuse themselves in every direction through space. 78. Colorless gases are invisible, and this explains why their existence is unknown or unreal to the ignorant. Air, illu- minating gas, ''natural gas" (which is mainly marsh gas, or methane), gasolin vapor, oxygen, hydrogen, ether vapor, alco- hol vapor, are invisible. But there are also a few colored gases, as chlorine, which is greenish; iodine vapor, which is violet; nitrogen tetroxide, which is red, etc. 79. The term vapor is used to designate gases which exist as such only at temperatures above the ordinary, and which, under ordinary conditions of temperature and pressure, assume the liquid or solid state. 80. In physics (485) the word fluid is used to designate any or all bodies whose molecules easily change their relative posi- tions within the mass — in other words, to designate liquids (74), gases (77) and vapors (79). 81. The three different "states of aggregation " depend upon the relative force of molecular attraction and repulsion. When the attractive force (cohesion) exceeds the repellant force the body is solid; when molecular attraction and repulsion are equally balanced the body is a liquid; and when the repellant force predominates, the gaseous state is the result. It is, therefore, said that " cohesion is absent in gases." It is, however, not absent, but simply rendered inoperative. 1 8 PHYSICS. 82. Many substances are capable of assuming either of the three states of aggregation. • Others again only one; and others two. Carbon is known only in the solid state; lead is known as a solid, and in its fused condition as a liquid, but not as a vapor; water is solid, as ice, liquid in its ordinary condition, or gaseous as water vapor. 83. Fixed substances are such substances as can not be made to assume the gaseous state. Volatile substances are liquids and solids which are very easily converted into vapor (79). CHAPTER IV. CRYSTALLINE BODIES. 84. Crystals are regular geometric solids with smooth faces meeting in straight edges and forming perfect angles or corners bounded by three or more of the faces (Fig. 6.) Crystals are formed by a definite arrangement of the mole- cules of matter in accordance with natural laws. Figure 6. 85. That the crystalline form depends, at least in part, upon the attraction called cohesion (55) is self-evident; but it is not PHYSICS. 19 known why or how the molecules of any particular kind of mat- ter thus arrange themselves into given forms. 86. Numerous examples of crystallization are found in the mineral kingdom. Mineral crystals formed in the interior of the earth were probably produced from matter in a state of fusion at extremely high temperatures. The remarkably pure calcspar (calcium carbonate) from Iceland, the pure silicic acid known as rock crystal, and the highly prized diamond (carbon) are beautiful examples of crystals. The Iceland spar is a prism, rock crystal is a prism with pyramidal ends, and the diamond is a double pyramid (112). Galena (lead sulphide) furnishes an example of the cubical form (130). But fine specimens of crystals may also be produced in the laboratory, and even commercial chemicals frequently exhibit well formed crystals. You might find some good crystals of copper sulphate, ferrous sulphate, alum, zinc sulphate, lead acetate, quinine sulphate, and many other substances. 87. There are innumerable forms of crystals, but as a rule each particular kind of matter crystallizes in but one form; rarely the same substance crystallizes in two or even three forms. 88. As each crystallizable substance generally forms but one kind of crystals, the crystalline form is one of the means of identification of the respective species of matter. Thus, knowing that potassium iodide crystallizes in cubes and in no other form, we know also, that any substance exhibiting some other crystalline form can not be potassium iodide. 89. Crystallizable substances are those capable of assuming a crystalline form. Crystallic substances are those occurring in comparatively well defined, free or detached crystals; like copper sulphate, alum, potassium bicarbonate, sodium phosphate, lead acetate, quinine sulphate, salicin. Crystalline substances are those having an evident crystalline structure, but not consisting of well developed and detached crystals; as ferric chloride, potassium acetate, black antimony sulphide, camphor, bismuth subnitrate. 90. Dimorphism. — Substances capable of crystallizing in two different forms are said to be dimorphous . 20 PHYSICS. Calcium carbonate occurs, as calcspar, in rhombohedrons of the hexagonal system, and, as arragonite in prisms of the rhombic system. 91. Polymorphism. — Substances occurring in more than one distinct crystalline form are sometimes referred to as poly- morphous bodies. Trimorphous substances are those occurring in three different crystalline forms, of which titanic oxide is an example. 92. Changes in crystalline form often result from different proportions of water of crystallization (121) . 93. Isomorphous substances are different substances crys- tallizing in the same form. Entire groups of chemically related compounds may have similar crystal- line forms. Bromide and iodide of potassium both crystallize in cubes. But the term isomorphism is understood to involve more than similarity or sameness of crystalline form (94). 94. In 1819 Mitscherlich made the important discovery that compounds of analogous chemical structure may not only have the same crystalline form, but that the corresponding elements in their constitution may be inter- changeable in any proportion. The double salts called a/ums are examples of perfect isomorphism. They are formed from the sulphates of either potassium, sodium or ammonium, with the sulphates of either aluminium, iron or chromium, all giving crystals of the same form (Octohedrons), and the respective sulphates of potassium, sodium and ammonium are mutually inter- changeable, in whole or in part, in these several kinds of alums, as are also the aluminic, ferric and chromic sulphates. But even bodies not completely analogous as described, may have the same crystalline form. Mitscherlich concluded that all molecules containing the same number of atoms arranged in the same manner have the same crystalline form, without regard to the kinds of atoms entering into the molecules. This rule has, how- ever, been found to be subject to many exceptions. Kopp regards as iso- morphous only compounds the crystals of which can grow in each other's solutions. A crystal of common alum will increase in size when placed in a solution of iron alum; hence these alums are isomorphous. 95. Heteromorphous substances are any two or more sub- stances which crystallize in different forms. 96. Amorphous substances. — Literally translated the word amorphous means formless. In chemical physics and in the description of pharmaceutical chemicals and other substances PHYSICS. 21 the term is used to designate substances without any indications of crystalline structure. 97. It is not to be supposed, however, that the forms assumed by all amorphous solids are devoid of regularity when their molecules are permitted to range themselves in comparative freedom. On the contrary where the straight lines and the perfect angles and faces of the crystal are absent, we may expect indications of a tendency to a spherical or bead-like form. Substances which take part in the physiological processes of animal or vegetable life, belonging to what has been called "organized matter," have not the property of forming crystals, although crystallized substances are fre- quently found deposited in the tissues of both plants and animals. Amorphism is the rule and the crystalline form exceptional among nat- ural products derived from the animal and vegetable kingdoms. Cellulose, starch, gum, albumen, and many other proximate principles contained in plants, are amorphous. Examples of inorganic amorphous solids are found in clay, ferrous sul- phide, zinc oxide, ferric hydrate, basic ferric sulphate, aluminum hydrate, precipitated calcium phosphate, and yellow oxide of mercury, as prepared in accordance with the pharmocopceias. 98. Many substances occurring in amorphous conditions may, however, also exist in crystalline forms. Moreover, numerous substances, which to the unaided eye appear without the slighest evidence of crystalline form, and which occur as impalpable powders, and are, therefore, described as amorph- ous, consist in reality of minute crystals plainly visible under the micro- scope. The latter may be called micro-crystalline. 99. When liquids are divided into minute particles, each particle assumes a spherical form by virtue of the force of cohesion, and retains that form until its cohesion is overcome by some other force, as by adhesion. A drop of oil retains its spherical form when floating in a liquid of equal density in which the oil is insoluble; but it loses its form when resting upon the surface of some solid. 100. Crystals grow from without by the deposition of additional solid matter upon their surfaces. Each larger crys- tal is then an aggregation of innumerable smaller crystals of the same form. Each smallest crystal in such an aggregation may be regarded as an individual. Whether or not the crystalline form represents the form of the molecule itself is a secret of nature which may perhaps never be discovered. 101. Being solids, all crystals must of course extend in at least three directions. Sometimes their extension is in four directions. 22 PHYSICS. CHAPTER V. HOW CRYSTALS ARE FORMED. 102. Axes. — The directions of extension of crystals are called their axes. These are imaginary straight lines intersect- ing each other at one point in the center of the crystal, and ter- minating either in the centers of opposite faces, or in the apices of opposite solid angles. 103. Planes or Faces. — The smooth, plane surfaces of crystals are called faces. They are bounded by three or more straight sides, each side matching that of the contiguous face. The smooth surfaces exposed by cleavage are the faces of crystals. According to the number of their faces crystals are called " tetrahedrons " when they have four faces, "hexahedrons" when they have six, " octohe- drons" when they have eight, "dodekahedrons " when they have twelve faces, etc. 104. Edges are formed by any two contiguous faces. These edges, or angles of incidence, or the respective inclination of the faces to each other, are characteristic of the primary forms of each particular species, and thus furnish the means of deter- mining which system crystals belong to, by measuring their facial angles. This is done with the aid of an instrument called a goniometer. 105. Angles. — The angles of crystals are the solid angles formed by three or more contiguous faces meeting in a point. Thus each corner of a cube is a three-faced angle; the apex of a hexag- onal pyramid is a six-faced angle; and octohedrons have six four-faced angles According to the number of their angles crystals are called tetragons, hex- agons, octagons, etc. 106. Fundamental Forms of crystals are the simple dom- inant forms of the several systems (129). 107. Simple Forms. — Crystals bounded in all directions by similar faces are called simple forms, as shown in galena and in the diamond (Figs. 7 and 8). 108. Complex Forms, are those having dissimilar faces, as shown in the rock-crystal and the calcspar. Complex forms are always combinations of two or more simple forms. PHYSICS. 2 3 The largest faces in a complex crystal are called the dominant faces because they determine the dominant form of the combination. The smaller faces are called subordinate ox secondary faces. Figure 7. Figure 8. 109. Crystal forms in which all the possible faces are pres- ent, making the crystal complete, are called holohedral forms. When only one-half of the normal number of faces are pres- ent, the crystal being thus only one-half developed, the form is called hemihedral. Forms with only one-fourth of the normal number of faces developed are also known. 110. Cleavage.— By carefully-directed gentle blows, or with the edge or point of a knife, an irregular mass of a crystal- line body, or a single crystal, can be split in certain directions so that plane, smooth faces are produced. The body can then be split into layers parallel with the surfaces thus exposed. This is called cleavage. The crystal or mass frequently splits more readily in one direction than in others. A perfect crystal may thus be obtained by the dissection of an apparently shapeless mass in the directions indicated by the cleavage. The simple form from which a secondary form is derived, may be discov- ered with the aid of cleavage dissection. Thus a hexagonal prism of Iceland spar may be reduced by cleavage to an obtuse rhombohedron. 111. The axis of symmetry is an imaginary straight line drawn through the center of the crystal, and around which its parts are symmetrically arranged. 24 PHYSICS. 112. Three general forms of crystals are to be distinguished: the cubical form, the prism or long columnar form, and the pyra- mid or pointed form. These forms are modified and combined into numerous varieties. Thus there are prisms with pyramidal ends, double pyramids, or two pyramids placed base to base. etc. The cube is seen in potassium iodide; the prism in Rochelle salt; the pyramid in potassium sulphate. 113. Prisms are called open for ms because their lateral faces are parallel so that the length of the crystal is indeterminate. Pyramids and double pyramids are called closed forms because they terminate at the apices. 1 14. Crystalline structure in soluble bodies when not apparent on the sur- face, or when so confused that the form can not be recognized, may often be discovered by slow solution of the broken crystals on the exterior. This may be affected by means of a nearly saturated solution of the same substance, such a weak solvent being sufficient to break down the fragments of already broken crystals but not sufficient to overcome the cohesion of whole faces and angles. 115. Crystalline form as an evidence of definite chemi- cal composition. — Only bodies having a definite chemical structure are capable of assuming the crystalline form. A substance known to be crystallizable is less liable to sus- picion as to its purity when in crystals than in any other condi- tion. But a crystallic form is far from sufficient evidence of purity, for not only do isomorphous substances crystallize together, but the crystals of one salt, however distinct, may still contain small amounts of heteromorphous salts as impurities. 116. Crystallization is resorted to as a means of separating salts from each other, and thus for purposes of purification, because substances which do not crystallize in the same form do not crystallize together in the same crystals. Perfect purification or complete separation by crystallization is, however, difficult unless the several substances to be thus separated from each other dif- fer in solubility, when the less soluble substance will crystallize before the more soluble one. 117. The presence of one substance in the solution of another may have the effect of causing the latter to crystallize in the form peculiar to the other. PHYSICS. 25 Thus, if a solution contain the sulphates of copper and iron (ferrous), and there is more than one molecule of ferrous sulphate present for every eight molecules of the copper sulphate, the copper salt will crystallize in mon- oclinic prisms, which is the form of the crystals of ferrous sulphate, instead of in the triclinic form, which is the normal form of crystals of copper sul- phate (Lecoq de Boisbandran). 118. Crystallization. — Crystals are most readily and com- monly formed when substances pass from a liquid or a gaseous condition into the solid state. Crystallization may, however, also take place in a solid body without previous fusion, solution or vaporization, as for instance in arsenous oxide, which slowly changes from the colorless, glassy, transparent amorphous to an opaque, white, crystalline condition. A similar change from a glassy structure to a more or less distinctly crystalline character is also to be seen in so-called barley sugar, or melted candy, as when clear lemon drops change to an opaque condition. 119. How crystallization is effected. — Solution, fusion and sublimation are the usual means of inducing crystallization. Large, well-defined crystals are frequently obtained when crys- tallizable salts slowly deposit from solutions of suitable degree of concentration. Highly developed crystalline forms are also sometimes obtained by fusion and by sublimation. Minute crystals are often formed when new compounds are produced by precipitation. CHAPTER VI. WATER OF CRYSTALLIZATION. 120. Anhydrous crystals are those which contain no water of crystallization (121). They may, however, contain small amounts of interstitial water impris- oned between the individual crystals. In that case they often burst asunder with a slight explosion when heated. This is called decrepitation, and sodium chloride affords a familiar illustration of it. Heat a crystal of common salt and see how it bursts with a smattering noise. 26 PHYSICS. 121. Hydrous crystals contain water essential to the crys- talline form. The water entering into the composition of hydrous crystals is called water of crystallization. 122. Some salts combine with various proportions of water of crystallization, according to the temperature at which the crystals are formed, assuming different forms according to the amount of water they take up. Manganous sulphate crystallized at or below 6°. C. (42°.8 F.) contains seven molecules of water; crystallized at from j°. to 20°. C. (44°.6 to 68°. F.) it contains five molecules, and when crystallized at 20 . to 30 . C. (68°. to 86°. F.) it takes up only four molecules of water of crystallization. Sodium phosphate when crystallized from a solution saturated at about 30 . C. (86°. F.) contains twelve molecules of water; but a solution saturated at 40 . C. (104 . F.), or over, will, on cooling, deposit crystals with only seven molecules of water of crystallization. Sodium carbonate as found in commerce contains ten molecules of water; at 30 . C. (86°. F.) it may be obtained with nine molecules, at 25 . C. (77°. F.) with seven, and at 12 . C. (53. °6 F. ) with five molecules of water. Copper sulphate ordinarily crystallizes with five molecules of water. If, however, an effloresced crystal of nickel sulphate be added to a supersaturated solution of copper sulphate, crystals of the latter salt are deposited which con- tain six molecules of water; but if a crystal of ferrous sulphate be instead added, the crystals obtained contain seven molecules of water. Zinc sulphate ordinarily contains seven molecules of water of crystalliza- tion; but when crystallized from a warm (over 30 . C.) concentrated solution the crystals formed contain only five molecules of water. 123. Some hydrous salts readily part with their water of crystallization even at ordinary temperatures, losing their crys- talline form, usually falling into powder, and are then said to effloresce (73). Others lose their water of crystallization without losing their crystalline form and then become opaque, as acetate of copper. At temperatures above summer heat many hydrous salts effloresce, and when heated up to about ioo° C. (212 F.), most of them give up the greater part of their water of crystallization. In many cases it requires very high heat to expel all of the crys- tal water, as for instance is the case with the sulphates of zinc and iron. PHYSICS. 27 124. Not all of the water of crystallization is held by the substance with the same force. Magnesium sulphate (Epsom salt) gives up one of its seven molecules of water at 30 . to 52 . C. (86°. to 126 . F.); four additional molecules of water are expelled by water-bath heat; and by stronger heat the salt may be rendered anhydrous. Potassa-alum contains 45.57 per cent, of water of crystallization. When heated to 40°. C. (104 . F.) it loses about 2.7 per cent, of that water; at 47° C. (116. °6 F.) it loses 9.6 per cent.,; at 6o°. C. (140 . F.) it loses most of its water, but the crystals still retain to a great extent their form, and the product, which is not yet porous, yields a clear solution with water; at 8o°. C. (176 . F.) the alum effloresces completely, but still holds a considerable amount of water; long continued heating at ioo°. C. (212 . F.) expels all of the water and leaves a product which is entirely water-soluble; when heated at once at over 92°. C. (197 . F.) the alum undergoes aqueous fusion (538), and the liquid does not solidify again until after standing a considerable time; when very gradually raised from the ordinary temperature up to 200 . — 205 . C, so carefully that all Of the water is expelled without aqueous fusion of the salt, the residue, or dried alum, is light and porous; should the heat be too low, a glassy mass may be obtained which can not afterwards be rendered porous, and in this glassy condition the alum is said to retain fourteen of its original twenty-four mole- cules of water. Crystallized ferrous sulphate contains seven molecules of water; when moderately heated it dissolves in this water of crystallization; between 33 . C. (91. °4 F.) and 90 . C. (194°. F.) the salt loses nearly six molecules of that water, but to quite expel the sixth molecule requires continued heat at about 120 . to 150 . C. (248 . to 302°. F.), which is liable to partly decompose and dis- color the substance; the seventh or last molecule can not be expelled until the heat rises to 280 . C. (536°. F. ) which almost certainly destroys a portion of the salt itself. Sodium phosphate crystallizes with twelve molecules of water; when heated to 35°. C. (95 . F.) it begins to dissolve in its water of crystallization, but does not liquefy perfectly until the temperature is raised to about 40 . C. (104°. F.); if now allowed to cool again it solidifies into a mass of a radiated crys- talline appearance; above 40°. C. (104 . F.) it loses five molecules of the water; at ioo°. C. (212 . F.) all of the water is expelled and anhydrous sodium phos- phate remains; gradual efflorescence of crystallized sodium phosphate in dry warm air, on the other hand, leaves a residue containing seven molecules of water. 125. The water contained in crystallized salts often materi- ally affects their color. 28 PHYSICS. Thus the sulphate of copper is blue, and ferrous sulphate bluish-green when crystallized; but both are white when dried. Hydrous cobalt chloride is garnet red, but the anhydrous blue. 126. Salts which are decomposed when they come in con- tact with water may nevertheless contain water of crystalliza- tion, as is the case with normal bismuth nitrate. CHAPTER VII. CLASSIFICATION OF CRYSTALS. 127- Crystallography is the science of naming, classifying and describing crystals, and of determining their forms Theoretically it is a branch of mathematics; practically it serves as an important means of recognizing minerals, salts, and other substances occur- ring in a crystalline form. 128. The numerous distinct forms which the crystals may assume depend mainly upon three governing conditions: 1, the number of the axes; 2, the angles at which the axes several intersect each other; and 3, the lengths of the axes, respectively. 129. The Six Systems. — The known crystalline forms are classed into six principal groups or systems based upon the number, andthe relative inclinations and lengths of their axes. Five of these systems have three axes; the hexagonal system alone has four axes. Those systems in which the axes intersect each other only at right angles are called Orthometric systems. They are the Regu- lar, Quadratic, Rhombic, and Hexagonal Systems. Those systems in which a part or all of the angles formed by the intersection of the axes are oblique, are called Clinometric, and consist of the Monoclinic and Triclinic Systems. The six crystallographic systems are as follows: PHYSICS. 2 9 130. The Regular System. — (The Monometric, or Tes- sular, or Cubic System.) Axes three in number. All three axes of equal length. Axial angles all 90 . The fundamental forms of this system are the cube, the regu- lar octohedron, and the rhombic dodekahedron. All the axial and facial angles of the Cube are right angles, it has twelve edges, its six faces are perfect squares, and its eight equal solid angles are three-faced. Each of its faces is at right angles to one axis, and parallel with the two other axes. A perfect cube may be built upon its axis by simply placing a plane at right angles against each end of each axis. Gold, silver, platinum, coper, sodium chloride, potassium iodide, and many other substances crystallize in cubical forms. Fig. 9. Regular Octohedron. Fig. 11. Rhombic Dodekahedron. 131. The Regular Octohedron is formed by the trunca- tion of the solid angles of the cube, or when each end of each axis is connected by straight lines (or rather, planes) with each end of each of the two other axes. The figure thus produced is a double, square-based pyramid bounded by eight equal equilateral triangles, has twelve edges, and six four-faced equal solid angles. The angles formed by the edges which are in the same planes, meeting in the apices of the solid angles, are right angles. Diamond, alum, and magnetic iron ore crystallize in regular octohedrons. 132. By placing a plane in such position that it connects two axes but runs parallel with the third, or by replacing each of the twelve edges of the octohedron, the Rhombic Dodeka- hedron results. 3° PHYSICS. This has twelve equal rhombic faces, and fourteen solid four-faced angles. Garnet phosphorus and cuprous. oxide crystallize in dodekahedra. 133. In addition to these forms there are others, less simple. Combina- tions of the simple forms can be easily imagined. Thus we may imagine a cube and an octohedron with axes coinciding with each other in all respects except that the axes of the cube are somewhat shorter than those of the octo- hedron; the result would be an octohedron with all its solid angles slightly truncated by the faces of the cube. (See Plate B.) Galena and lead nitrate show such compound forms. For the purposes of this book, these examples of the manner in which the simple forms may be modified, are sufficient. Similar modifications occur in all the six systems. < —J- >i Fig. 12. Double Six-sided Pyramid. Fig. 13. Six-Sided Prism. Fig. 14. Quartz Crystal. 134. The Hexagonal System. (The Rhombohedral Sys- tem.) Axes four in number. Three of these axes are of equal length, and they are called the secondary axes. The fourth axis, which is called the primary axis, is either longer or shorter than the other three. The secondary axes are all in the same plane, and cut one another at angles of 6o° '. The primary axis is at right angles to the plane of the other three. The fundamental form is the double six-sided pyramid, bounded by twelve equal isoceles triangles, and having eight PHYSICS. 31 solid angles, two of which (one at the apex of each pyramid) are six-faced, the other six being four-faced. Other important forms are the regular six-sided prism and the rhombohedron. Rhombohedrons are formed by extending alternate faces of the hexagonal pyramid until they cover the others. Fig. 25. Rhombohedron. (Hemihedral.) Fig. 26. Combination of Rhombohedron and Prism. Many substances crystallize in hemihedral forms of this system. Calc spar, rock crystal, ice and sodium nitrate crystal- lize in forms belonging to the hexagonal system. 135. The Quadratic System — (The Di- metric, Square, Prismatic, Pyramidal, or Tetra- gonal System). Axes three in number. The two secondary axes are of equal length . The third or primary axis, longer or shorter than the other two. The axial angles all 90 . Pyramids of this system have square bases. Fig. 27. Scalenohedron with Inscribed Rhombo- hedron. 32 PHYSICS. Fig. 28. Square-based Double Pyramid. Fig. 29. Fig. 30. Prism of Quadratic System. Form seen in the Sulphates of Magnesium and Zinc. Fig. 31. Crystal of Potassium Ferro- cyanide. Fig. 32. Quadratic Prism with Pyramidal Ends. F ig- 33- Crystal of Stannic Oxide. The primary forms are the double four-sided, square-based pyramid and the right square prism. Potassium ferrocyanide, mercuric cyanide, magnesium sulphate and zinc sulphate crystallize in forms of this system. 136. The Rhombic System. — (The Trimetric, or Right Prismatic System.) Axes three in number. All the axes are of unequal lengths. The axial angles all 90 . PHYSICS. 33 Fig. 34- Rhombic Pyramid. Fig. 35- Rhombic Prism, with Pyramidal Ends. (Zinc Sulphate). Crystal of Potassium Sulphate. The fundamental form is the right rhombic double pyramid, or rhombic-based octo-hedron. Sulphur and potassium sulphate crystallize in forms belonging to this system. Fig. 37- Monoclinic Double Fig. 38. Crystal of Sodium Acetate. (Monoclinic Prism.) Fig. 39. Crystal of Cane Sugar. Pyramid. 137. The Monoclinic System.— (The Monosymmetric or Oblique Prismatic System.) Axes three in number. All the axes are of unequal lengths. The two secondary axes are at right angles to each other. The primary axis is at right angles to one of the secondary axes, but forms oblique angles with the other. The primary form is the monoclinic pyramid. 34 PHYSICS. Ferrous sulphate, borax, potassium chlorate, sodium acetate, sodium thisosulphate, sodium sulphate, sodium carbonate and sodium phosphate furnish examples of monoclinic crystals. Cane sugar also crystallizes in forms of this system. 138. The Triclinic System. — (The Asymmetric, or Doubly Oblique Prismatic System.) Axes three in number. All the axes are of unequal lengths. All the axial angles oblique. This is consequently the least regular of all the systems. Fig. 40. Fig. 41. Fig. 42. Crystal of Gypsum. Triclinic Prism. Calcium Truosulphate. The fundamental form is the triclinic pyramid. Copper sulphate, potassium bichromate, boric acid, manganous sulphate and bismuthous nitrate crystallize in triclinic forms. 139. Cubes belong to the Regular System. Prisms are to be found in all except the Regular System. Prisms with rectangular sides belong to the Hexagonal System if six- sided; to the Quadratic System if four-sided. Prisms with oblique angles or rhomboid sides and bases belong to the Monoclinic System, if any two of their axes are at right angles; to the Triclinic System when they have no right axial angles. Pyramids belong to all of the six systems. Those with square bases belong to the Regular System if the three axis are of equal length, the faces being then equilateral triangles; to the Quad- ratic System when one axis is longer or shorter than the other two, the faces being then isoceles triangles. Pyramids with hexagonal bases belong to the PHYSICS. 35 Hexagonal System; their faces are isoceles triangles. Pyramids with rhom- bic or rhomboid bases belong to the Rhombic System, when all the axes are at right angles; to the Monoclinic System when any two axes are at right angles; and to the Triclinic System when there are no right axial angles. 140. Among the terms used in the pharmacopoeial descriptions of crys- tallic substances, the following terms are also found, all of which explain themselves, viz.: tabular, laminar, scaly, acicular (needle-shaped), feathery, and vuarty crystals, etc. CHAPTER VIII. ADHESION. 141. Adhesion is the attraction which operates between the unlike molecules of different substances in whatever state of aggregation. It may operate between solids, solids and liquids, or solids and gases; between liquids, or liquids and gases; or between gases. Dust, soot and mud adhere to houses, furniture, clothing, and other solid bodies; the printer's ink adheres to this page by the same force — adhesion; and cements of various kinds are useful on account of their adhesive nature. 142. Adhesiveness. — Many substances are adhesive or sticky; but their stickiness is by no means sufficient evidence of their strength or utility for the purpose of holding solid bodies together. Nor does anyone adhesive substance show the same adhesion for all other substances. 143. Dry, hard solids are not adhesive in that condition; but may become so upon being moistened or dissolved, and then the strength of their adhesion is generally greatest upon again drying or hardening in contact with the surfaces to which they are applied. 144. Viscous substances like tar, honey, etc., may be very sticky and yet useless as agents for fixing solids firmly together. The strong adhesive power of cement, glue, mucilage and varnish, is familiar to you. The best grades of glue and of hydraulic cement have an adhesive strength equal to about five hundred pounds to the square inch. 36 PHYSICS. 145. But different kinds of adhesive substances are used for different materials. Cement is used to hold stones together; mortar for stone and brick; glue for wood; mucilage for paper; gum-resins for glass, etc. Glue adheres to wood but not to metals; pitch sticks to your fingers if they are dry but not to wet fingers; mucilage adheres to paper and cloth, but not to greased paper or cloth. 146. Dry gum (acacia) is not sticky, but a strong solution of gum (muci- lage) is remarkably adhesive. Dry resin (common "rosin") is not sticky, but a solution of it in either alcohol or oil of turpentine exhibits a strong adhesion, while a solution of resin in olive oil is sticky but does not consti- tute a good or strong cement because it does not dry. 147. In all the instances described in the preceding, the adhesion, although a molecular attraction, seems to operate only between whole bodies of molecules and not between the molecules themselves, but the attraction is only between the molecules which form the surfaces of respective bodies which adhere together. . There are, however, very common and important phenomena of adhesion extending to each and all of the molecules of the bodies concerned as in solu- tion (183). 148. Heterogeneous bodies, or mechanical mixtures are sometimes so coarse that we can readily recognize the several ingredients in them and thus see that they are composed of unlike masses of molecules, although the ingredients may adhere sufficiently to form one mixed body. Building mortar made of sand, lime and water, is easily seen to be a mixture. 149. Miscibility. — When dry solids are mixed with each other, as in " species " or mixed teas and in compound powders, there may be but faint signs of adhesion between the several ingredients. Liquids between which there is no adhesion are not micible without the intervention of other substances; thus water and oil, mercury and water, chloroform and water, do not mix (195 and 196). When solids and liquids are brought into contact with each other, the solid is wetted by the liquid if there is any adhesion between them, but otherwise not. Mercury does not wet the bottle containing it, while water does; but water does not wet a greased dish. PHYSICS. 37 150. Pharmaceutically homogeneous mixtures are mechanical mixtures so well prepared, or in which the ingre- dients are so intimately blended, that they appear as if perfectly uniform, although they may contain solid masses of molecules of different substances. A well-made ointment containing an insoluble powder may be made so smooth and perfect that the particles of powder can neither be seen nor felt. A compound powder may be made so uniform that the different ingre- dients can be recognized only by the aid of the microscope. In " blue mass " and " blue ointment," if properly made, no globules of mercury are visible to the unaided eye. An emulsion of a fixed oil can be so thoroughly prepared that no oil globules can be detected in it except with the aid of a good microscope. Yet, tn all of these mixtures the ingredients consist oi large bodies of molecules, each particle of each ingredient containing numerous molecules. 151. Mere mixtures may, indeed, sometimes be so intimate as not to be recognizable as mechanical mixtures, except by chemical means. The air is a mixture of oxygen and nitrogen so perfect that the compo- nent ingredients are not to be detected by physical means; but the air pos- sesses the properties of both gases, and is in reality a mere mixture of the molecules of oxygen with the molecules of nitrogen, and the completeness of the mixture is not affected by the proportions. It is to be remembered that gases diffuse between each others molecules in this intimate manner because their molecules tend to separate from each other (77). CHAPTER IX. CAPILLARITY AND OSMOSIS. 152. Capillarity. — If you place a perfectly clean glass plate in a vertical position in a vessel of water, the water will ascend on each side of the plate to a height of nearly one-sixth inch, 38 PHYSICS. being drawn up by the adhesion between the glass and the water, the force of that adhesion being greater than the cohesion between the molecules of water to that extent. But the column of water above the surface must in this case be supported not alone by adhesion between the glass and the water, but aided by the cohesion in the water itself. 153. If a second plate of glass be placed parallel with and close to the first, the water will rise between the two plates higher than it did when only one plate was used, and, within certain limits, the column of water between the plates will be higher, the nearer the plates are brought to each other. When the plates are j^ inch apart, the water will rise between them to the height of two inches. 154. If the two plates are so placed as to form an acute angle as shown in fig. 43, the water rises highest at the point where the plates touch each other. Fig. 43- 155. If a number of tubes of different diam- eters be placed together in a tumbler half filled with water, the water will rise in each tube a different height in inverse proportion to the diameter of the tube. The smaller the diameter of the tube, the higher the column of water in it. Fig. 44- Fig. In a tube of T ^ inch diameter the column of water supported by the adhesion between the glass and the water will be four inches high. 156. All of these phenomena are caused by adhesion, and the form of adhesion which causes liquids to rise upon the sur- faces of solids is called capillary attraction or capillarity, because it PHYSICS. - 39 is most strikingly evident in tubes of such small diameters as to resemble hairs. 157. Capillary attraction is most familiar to us through the action of blotting paper and of lamp wicks. The blotting paper absorbs ink, water and many other liquids by its capillarity. Lamp wicks carry the oil from the reservoir or fount of the lamp to the burner. Fig. 45. 158. If a lamp wick or a strip of toweling be placed with one end in a vessel containing a liquid, the other end hanging down into an empty vessel (Fig. 45), it acts as a siphon (297). 159. The reason why a liquid can not easily be poured out of a full tumbler, or other vessel having no lip or flaring rim, Fig. 46. Fig. 47- Illustration of the Utility of the Guiding Rod. without spilling and without running down along the outside of the vessel, is that the attraction between the liquid and the surface of the vessel draws them together. To prevent this we may grease the edge or rim of the vessel, to prevent the capillary attraction, or we may use a guiding rod to divert it (Fig. 47). Lips are formed on graduated glass measures (" graduates "), pitchers, 40 PHYSICS. pans, dishes, mortars, beakers, and other vessels in order to avoid the incon- venient results of capillary attraction — spilling, and the wetting of the outside of the vessel. Lips and guiding rods give the proper directing to the stream. 160. But capillary attraction is exhibited only when the liquid wets the surface of the vessel or tube (149). As water wets glass while mercury does not you will find that water poured into a small graduate or tube forms a concave surface being drawn upward along the edges, while mercury, on the contrary, forms a convex surface. 161. A dry lamp-wick or dry blotting paper will absorb and convey any liquid which wets it; but if the wick or paper be saturated with one liquid it will not afterwards convey another liquid immiscible with the first. Thus a lamp-wick wet with water will not draw oil, nor will a wick saturated with oil take up any water. 162. In U-shaped tubes such as shown in Figures 48 and 49, mercury not only forms convex surfaces in both branches, but is depressed in the smaller branch, while water forms concave surfaces in both branches and ascends higher in the smaller branch than in the larger. Fig. 48. Fig. 49 . 163. But not all liquids affected by capillarity rise to the same height in tubes made of the same material; nor does any one liquid rise to the same height on one solid as on another. In a glass tube we find that alcohol does not rise much over one-half as high as water, nitric acid three-fourths as high, but a solution of ammonium carbonate higher than water does. On the other hand, mercury rises on lead and zinc although it does not rise in glass tubes. 164. It has been shown that liquids do not rise on solids unless the adhe- sion between the solid and liquid exceeds one-half of the force of the cohe- sion of the liquid. 165. If you put a strong water solution of ammonium chloride, or of lead acetate, in a shallow dish, and allow it to stand sufficiently long, solid matter will deposit along the edge of the surface of the solution, portions of the solution will rise by capillary action upon the solid particles and above them and (by spontaneous evaporation) deposit more solid matter, and this may continue until a crust of solid creeps over the edge of the dish and con- tinues on the outside. 166. In the extraction of soluble matters from plant drugs, as in making tinctures, fluid and solid extracts, etc., the PHYSICS. 41 menstruum or solvent used is absorbed into the particles of the drug by capillarity. By this force the water, or diluted alcohol, or even undiluted alcohol to some extent, is made to permeate every particle of the powder used. 167. Capillarity is absolutely necessary to vegetation and animal life. In dry seasons water is drawn to the surface of the ground by capillary action; the ascent of sap in plants, and the circulation of the fluids in the tissues of plants and animals is in great measure caused by the same force. 168. Diffusion of Liquids. — Miscible liquids (149) have a tendency to mix with each other, without any stirring or shak- ing, and even in apparent opposition to the law of gravitation. This tendency is called diffusion. "\ 7" Put some water, colored with red ink or cochineal, into a tall V J bottle or in a graduate; make a solution of one ounce of washing soda in four ounces of hot water and filter it; then pour the solution slowly through a thistle tube (Fig. 50), into the same bottle keeping the end of the tube at rest near the bottom of the bottle until all of the solution has been added. If you do not have a thistle tube, put the soda solution in the bottle first and then add the colored water, pouring this cautiously and slowly down along the sides of the bottle so that the two liquids will not mix. As the soda solution is denser it will temporarily remain at the bottom under the lighter water. But the tv/o liquids become gradually mixed with each other by diffusion until in the end the mixture is perfectly uniform. You may perform the same experiment with other liquids of different densities, as alcohol and water, water and glycerin, etc., coloring one of the two liquids used so that the result may be readil:/ Fig. 50. seen. The diffusion is uniform only in dilute solutions. 169. A bladder has no visible pores, and indeed, if you nearly fill a dry bladder with water and let it stand in an open vessel, no water will escape through the membrane . Water will be absorbed into the substance of the bladder, but no drops of water will appear on the opposite side. If you tie the bladder so tightly near its opening that no water can escape at that point, and then place the filled bladder in a screw press and apply pressure grad- ually, no water passes out of it until it bursts. You would regard it, there- fore, as water-tight. Parchment paper, also, holds water, although, like a bladder, it is wetted by water and absorbs that liquid into its substance; but it has no visible pores. 170. Yet, when such a membrane is placed between two liquids both 42 PHYSICS. capable of wetting it, currents may pass through the septum in either direc- tion, according to their kind and respective densities. Cell walls act in the same way. 171. These membranes or septa must, therefore, be porous diaphragms, notwithstanding the fact that no pores can be seen in them even when exam- ined with the highest powers of the microscope. 172. Osmose. — The diffusion of liquids through membranes (as described in the preceding paragraphs), is called osmose. 173. Osmose evidently depends upon capillary action (159 to 168). 174. The osmotic currents pass through the membrane in both directions, to and fro, until the liquids in both sides have the same composition. Should the liquids on both sides of the septum be the same from the beginning no currents can be detected; but if they are different and at the same time miscible, osmose takes place and continues until the diffusion has made them perfectly uniform. 175. But denser liquids move more slowly than lighter liquids through the membrane. Hence, the current toward the denser liquid is stronger than the current in the opposite direc- tion . 176. If a bladder is filled with a saturated solution (188), of potassium carbonate (common " potash "), a piece of broom stick inserted in the open- ing, the neck tied tightly to the stick, and the bladder then immersed in a ves- sel of water, the current of water passing into the bladder may be so much more rapid than the current of the solution of potassium carbonate passing out of it that the bladder may burst. 177- Osmose may be accounted for by the assumption that organic membranes consist of a network of solid matter, the meshes or pores of which are invisible because filled with water, this water being held with such force that it can not be expelled without destroying the membrane. Liquids miscible with water may thus be passed through the pores by the intersticial water. 178. Substances held in solution in water are capable of passing through organic membranes by osmose (172 to 177). But all water soluble substances do not act alike in this respect; PHYSICS 43 some substances pass through the septum comparatively rapidly, while others only pass very slowly. It is found that the sub- stances whose solutions diffuse through the septum most rapidly are either crystallizable or somewhat resemble crystallizable sub- stances chemically, while the other water-soluble matters — those that pass through the septum with great difficult)'-, or very slowly, if at all — include all that solidify in gelatinous masses like glue, gelatin, and gum, and other substanes forming vis- cous solutions. 179. For these reasons the term crystalloids is applied to all substances, which in a state of solution readily diffuse through organic membranes, and the term colloids is applied to all water- soluble substances which pass through such membranes with, difficulty. It should be remembered, however, that crystalloids are not all crystallizable, and that colloids do not all resemble glue in their external form. 180. The separation of crystalloids from colloids by means of osmotic currents, or by the diffusion of the crystalloids through an organic membrane, is called dialysis. 181. It has been found that water will pass through an organic membrane far more rapidly than alcohol. Fig. 51, represents an apparatus used to demonstrate that fact. Insert a long tube by means of a perforated cork or rubber stopper into a squatty bottle, the bottom of which has been removed. Tie a piece of bladder tightly over the open lower end of the bottle. Fill the bottle and part of the tube with alcohol. Then place ( the bottle in a shallow dish containing water. In the course of a few hours the liquid will have risen in the tube, and, if sufficient time be allowed, the water will at last have passed through the bladder in sufficient quantity to cause the liquid in the tube to overflow at the top. 182. Dialysis is employed in chemical analysis for the separation of crystalloids from colloids, and also in the arts and man- ufactures for the purification of products, etc. Fig- 5i- 44 PHYSICS. CHAPTER X. SOLUTION. 183. Solution is a complete molecular blending of any sub- stance with a liquid, resulting in a clear, homogeneous liquid product. The product of solution is also called a solution. The liquid employed to produce the solution is called a solvent. From the definition given above it will be seen that solution extends to the molecules; thus the molecules of the substance dissolved are so far separated from each other that the mole- cules of the solvent lie between them. Solution is, therefore, the most intimate and perfect union that can be effected of any substance with a liquid. It is the result of molecular adhesion. A solution contains no visible particles of solid matter. 184. Solubility. — Not all substances can be brought to a sta:e of solution. Thus, no solvents are known for carbon, the metals, and for numerous compounds. The capacity of any substance for being dissolved in a liquid is called its solubility. But any one substance may be soluble in one or more liquids, while insoluble in others. Whenever the word " solubility " is used without specifying the solvent referred to. it is understood that solubility in water is meant. Thus, when we say that alum is soluble, we mean that it is soluble in water. A soluble substance may be either solid, liquid or gaseous. 185. Ratio of Solubility. — The extent to which any sub- stance may be dissolved in any given solvent is also usually expressed by the word "solubility." Thus we say that the solubility of potassium chlorate (in water) is about 6 per cent., or about one ounce to the pint. Experience teaches that some substances are insoluble, others very spar- ingly soluble, others readily soluble, or freely soluble. 186. Solution modifies cohesion and density. When a solid is dissolved its cohesion is diminished, and it is thus rendered liquid. When, on the other hand, a gas is dissolved, the molecules of the gas are brought together, and the gas is condensed and liquefied. physics. 45 187. The substance dissolved of course always adds to the volume and weight of the solvent. 88. A saturated solution is one in which the adhesion of the solvent for the substance acted upon by it is satisfied, or one in which the adhesion between the solvent and the dissolved sub- stance is neutralized or balanced by the cohesion or the tension which oppose it. Such a solution is not capable of dissolving anymore of the substance it contains, but may, nevertheless, act as an effective solvent for some other solvent. A saturated solution of potassium nitrate is incapable of dissolving more potassium nitrate, but it can dissolve many other substances. 189. Solution affords striking illustrations of the extreme divisibility of matter. Thus, one drop of a saturated solution of copper sulphate (" blue vitriol ") put into a gallon of water will strike a decided blue color on the addition of a little strong ammonia water. A drop of tincture of chloride of iron in a gallon of water will assume a purple color on the addition of a grain of sodium salicylate. A grain of sugar of lead will make a gallon of water cloudy and on addi- tion of a few drops of diluted sulphuric acid a decided turbidity results. 190. There are two kinds of "solution" spoken of. True solution, or Simple Solution, is a solution in which the molecules of both the solvent and the substance dissolved remain unaltered. Chemical Solution is a solution in which the molecules of both the solvent and the substance dissolved disappear or are destroyed, other (new) molecules taking their place. When a piece of sugar is dissolved in a quantity of water, simple solution takes place, because the solution formed contains the molecules of the sugar and the water, and no new kinds of matter are produced. The solution exhibits the sweetness and many other properties of the sugar, and the solu- tion also partakes of the properties of the solvent: in fact, the sugar can be recovered again as solid sugar of the same kind as before by simply evaporat- ing (390) the water. But when zinc is dissolved in diluted sulphuric acid the solution which takes place is not simple solution but chemical solution, because the resulting liquid does not contain any molecules of zinc (nor any molecules of sulphuric acid, if the acid be saturated with the zinc) but does contain molecules of a salt called zinc sulphate formed by chemical action and which has entirely 46 PHYSICS. different properties from those belonging to zinc. Upon evaporation such a solution you would not get zinc,. but the white crystalline water soluble zinc sulphate. 191. A solvent producing simple solution is called a simple solvent, or a neutral solvent, while solvents producing chemical solution are called chemical solvents. The most common simple or neutral solvents are water, alcohol, ether, chloroform, petroleum spirit, glycerin, volatile oils and fixed oils. The most common chemical solvents are acids, alkali solutions, and the solutions of acid salts. 192. Substances in solution may be thrown out of the solution or precipitated by adding liquids in which they are insoluble. Gum (acacia) is soluble in water, but insoluble in alcohol; therefore, if alcohol is added to a solution of gum (mucilage) the gum is precipitated or thrown out of its solution. Any resin, as, for instance, benzoin, is soluble in alcohol but insoluble in water; hence the benzoin contained in the tincture of benzoin is thrown out of solution on the addition of water. 193. When a water solution of a salt is exposed to such a low temperature that congelation results, the ice formed does not contain the salt. The water freezes or crystallizes (118), and in doing so must separate from the solution. As the ice forms gradually, the solution maybe concentrated by the removal of the portions of ice as soon as they are formed. Plant juices, alcoholic liquids, etc., can be concentrated in the same manner. 194. Solution is a phenomenon of all pervading importance in its uses and results. In animals and plants nutrition would be impossible were it not for the liquefaction by solution of the substances appropriated as food The universal application of solution in the arts and manufactures ren- ders it necessary that it should be carefully studied. 195. Miscible liquids may be said to be soluble, each in the other. Thus it may be said that water dissolves glycerin and that glycerin dis- solves water, because the two liquids blend perfectly with each other (149). 196. If you have two miscible liquids, A and B, and if A is miscible also with a third liquid, C, it does not follow that B, too, is miscible with C. physics. 47 Thus, alcohol and water are miscible, and alcohol is also miscible with castor oil, but water and castor oil do not mix at all. Water is miscible with alcohol, alcohol with ether, ether with olive oil, and olive oil with oil of turpentine, but water does not mix with either ether, olive oil or oil of turpentine; the alcohol does not mix with olive oil or with oil of turpentine, nor the ether with oil of turpentine. The miscibility of one liquid with another, therefore, affords no indica- tion of its miscibility with a third liquid. CHAPTER XI. MOTION. 197. We have seen (60) that " dynamics treats of the states and motions of matter in its molar condition, and of the relations and results of molar attraction and repulsion." We have also read that Energy (58) is the power to do work, to overcome resistance, to produce or arrest motion; and that motion (59) is a change of place. Again, attraction and repulsion were described (35 and 36), and gravitation and weight were defined (38 to 41 incl.) The reader is advised at this point to turn back to the paragraphs referred to, and to carefully read them over again. Remember also that matter \s anything that occupies space and is affected by gravitation (3 to 6 incl.) 198. All matter is in motion (59), and, therefore, the terms motion and rest are merely relative terms. The earth itself is in constant motion. It moves around the sun at the rate of 19 miles per second, and at the same time whirls around on its axis at the rate of 1440 feet per second. But when you look at large buildings, or any other objects on the earth's surface it does not occur to you that they are traveling nearly a thousand miles per hour in one direction, and 68,400 miles per hour in another direction, because you are travelling at the same rate your- self, together with all the objects around you. If to this motion of the globe you add the molecular motions and atomic motion, it will not be difficult to see that no material object in the Universe is ever absolutely at rest. 4S PHYSICS. 199. The Laws of Motion. — Sir Isaac Newton pro- pounded the following "laws of motion.*' which are universally accepted and are of the greatest importance: 1. A body continues in a state of rest or of uniform motion in a tra ig -". t . 7 . t u . $c its state by a force external to itself. (See Inertia, par. 31.) 2. The change of [quantity of) motion is proportional to force, place in the straight line in which the force acts, j. To every action there is always an equal and contrary reaction; or, the mutual actions of .: ; two bodies are alwa rqual and oppositely ted. 200. The first law simply declares that matter is entirely distinct from all force, and that, therefore, matter itself can do nothing. 201. The second law means that any amount of force, how- ever small or great, in whatever direction applied, will have its corresponding effect, no matter what other forces may be at work simultaneously upon the body. The second law is also stated in the following words: A given force has the same effect in ring or producing motion^ whether the body upon which it acts is in motion or at res:; whether it is acted upon by that force alone or by others at the same r 202. The third law is less easily grasped. In modern phrase- ology it is merely this: " Every action between two bodies is a stress." I: is literally true that when you strike your fist against a stone, the stone reacts with equal force. A coat hanging on a hook retains its position because the hook reacts with a force equal to the pull of the coat. When a ball is fired from a cannon, the cannon recoils with a momentum (204) equal tc that of the ball, but the backward motion is much less because of the greater weight 0: the cannon If you hold a brick on your hand, the hand must press upward against the brick with precisely the same force as that with which the brick presses down against the hand. The brick is attracted by the earth, and when you turn your hand over and let the brick fall the earth moves to meet the brick for the attraction between the two bodies is mutual, but the mass of the earth being immeasurably greater than the mass of the brick, the earth moves so slightly that its motion is imperceptible. When a flying bird beats the air with its wings, the reacting force of the air, being greater than the v.eight of the bird, causes the bird to rise. PHYSICS. 49 203. The velocity of motion refers to the space traversed in a given time. 204. The Momentum of a body is the quantity of its motion. It depends upon the mass (7) of the moving body and upon the velocity (203) of its motion. 205. A body of great weight, moving with great velocity, has a greater momentum than a body of less weight moving with the same velocity, or a body of the same weight moving with less velocity. 206. The momentum (204) of a slowly moving freight train is greater than that of a bullet shot from a rifle, and both have a great momentum — the first because of its great weight, the second because of its great velocity. 207. We apprehend danger from the approach of large masses, instinct- ively associating them with great force, and we move out of their path; but we pay no attention to small bodies moving toward us. 208. A pebble thrown against a heavy plate glass window does not break the glass, but a large stone thrown with the same force will shatter it. 209. A large pestle gently placed upon a piece of alum in. the mortar so that the whole weight of the pestle rests on it does not crush the alum, but if the pestle be elevated and then allowed to fall upon the alum, the piece is broken. 210. Centrifugal force is the tendency of a body revolving around a center to continue its motion in a straight line, and thus to move further away from that center. In other words, it is simply the result of Newton's first law of motion (199). The mud is sent flying from the revolving wheels of a rapidly moving car- riage, and when the carriage turns a corner abruptly its tendency to move on in the straight line of its original direction may cause it to be overturned. 211. The Center of Gravity of a body is the point at which the whole weight of the body may be supposed to be centered, or that point at which the entire mass of the body may be balanced. To support any body it is only necessary to support its center of gravity. 212. In a compact body the center of gravity is within the mass; but in a hollow body, like an empty box, bottle, or hoop, the center of gravity is out- side of the space occupied by the matter of which the body consists, which is also the case in the arrangement represented in Fig. 54, which you can easily construct with a tumbler or goblet, two table forks, and a match. The forks 50 PHYSICS. are locked together at about right angles by inserting their respective prongs between each other, one end of the match is also inserted between the prongs, /^^^T ==: W^\ ' n tne an gl e » an d tne other end of the match ¥r~~^^^xCj 1S supported on the edge of the tumbler at 1 dST^^nT^L t ^ le P°^ nt immediately above the center of JBrl .;|i § ^"s;-. gravity. Thus you can support two forks on ^^r\ |j J n# one end of a match, the other end of which 0r I J^.ji^m .jm rests on the edge of a tumbler, without any A^j— '-^^^ other support whatever, and if the tumbler Fig. 54- is filled with water you can raise it to your lips and drink a portion of the water with the forks still hanging on the end of the match. Fig. 54. In a solid sphere the center of gravity is, of course, the center of the sphere. 213. Equilibrium. — When a body is at rest, the forces which act upon every part of its mass are said to balance each other and are said to be in equilibrium. A body is in equilib- rium when its center of gravity is supported. 214. A body is in stable equilibrium when supported in such a manner that, when somewhat displaced from its position, it re-assumes the same position as before. A cone resting on its base is in stable equilibrium. A body is in unstable equilibrium when so supported that a slight change in its position of equilibrium causes it tc fall further from that position. A stick balanced in a vertical position on the end of the finger is in unstable equilibrium. A cone resting on its apex is in unstable equilibrium. A body is in neutral equilibrium when so supported that it remains at rest in any adjacent position after it has been dis- placed. A solid sphere is in neutral equilibrium when resting upon a horizontal plane, and a cone lying on its side is in the same state. 215. The base is the side on which a body rests. The base of support of a table is the figure formed by straight lines con- necting the points where its legs touch the floor. * 216. The line of direction is the vertical line connecting the center of gravity of a body with the center of the earth. PHYSICS. 51 217. Stability. — The broader the base is, and the lower the center of gravity, the greater will be the stability of the position of the body. Hence, a tall stand must have a broad and heavy foot. If the line of direction fall within the base the body is stable, if the centre of gravity is above and outside the base, or (which is the same thing), if the line of direction be outside the base, the body must change its position. A ball rolls about easily, especially one of a hard material, like a billiard ball, because when it rests, it rests only upon a point. A cylinder, as a round lead pencil, resting upon a line, also requires but a slight impulse to move it. No elevation of the center of gravity is necessary to start .spheres and cylin- ders moving. 218. Velocities of falling bodies. — All bodies, without regard to mass or kind of matter, fall with equal velocity through space in a vacuum. A feather will fall as rapidly as a bullet through a vacuum. But if two bodies of different densities (10), fall through air, the denser body will reach the ground first, because it meets with less resistance from the air (199 and 202), than the less dense b>ody. 219. When bodies fall through a vacuum there is no reaction (199), or resistance; but reaction and resistance are always met when bodies fall through any fluid (80). 220. If several bodies, all consisting of the same kind of matter, but of different weights, as for instance, a number of iron balls of different sizes, be dropped at precisely the same time from a great height, they will all reach the ground at precisely the same time, the smallest ball as soon as the largest. Twenty horses together can not run any faster than one horse alone. 221. The fact that a dense body, like a small glass bottle, falls to the floor more rapidly than a cork of equal bulk, makes it appear as if heavy bodies fall faster than light bodies; but a quart bottle will fall no faster than a homoeopathic vial, and in a vacuum corks and bottles will fall with equal velocity. 222. The falling of bodies to the earth is the result of grav- itation (38), which affects all matter alike. While gravity is directly proportional to mass (7), and, therefore, a lead bullet must be attracted to the earth with greater force than a feather, the greater force of gravity acting upon the bullet has more work to pefrorm, or has to move a greater load. 52 PHYSICS. For the greater force to do the greater work requires as much time as for the lesser-force to do the lesser work (58). 223. As gravitation operates continuously upon matter, being a constant force, a falling body requires accelerated velocity in the act of falling. 224. A body starting from a condition of rest to fall of its own weight travels about4. 9 meters in one second. In the start, of course, it had no velocity, but as it began to move or have velocity, that velocity increased uniformly; its velocity at the end of the first second is such as would, if uniformly con- tinued, carry the body a distance of 9.8 meters during the next second. And as gravitation continues its pull without the least change, the velocity of the falling body continues to increase, so that instead of traversing only 9.8 meters the second second, the body falls through 14.7 meters, or three times the dis- tance it traveled in the first second. For the same reason the body travels through 24.5 meters during the third second, or 5x4.9; during the fourth second it falls 7x4.9 meters, etc. 3 225. A Pendulum, Fig. 55, is a weight suspended from a fixed point so as to swing (or "oscillate") freely to and fro, alternately by momentum and gravity. The most common form of a pendulum is a flexible steel rod loaded at the bottom with a heavy piece of metal called the bob. The bar or rod of the pendulum being in a vertical position, the center of gravity is at the lowest possible point. The pendulum is then at rest. But when the bob is moved upward and to one side, and then released, the pendulum is carried back to its vertical position by gravity, and inertia (31) carries it beyond Fig. 55. A Pendulum. that position, raising the bob again on the opposite side, until gravity stops the motion and pulls the bob down again. 226. Pendulums of the same length perform an equal num- ber of oscillations at the same place in the same time. 227. The times of vibrations of different pendulums at the same place are proportional to the square roots of their lengths. Thus, if one pendulum is four times as long as another, the time of vibra- tion of the longer pendulum will be twice as great as the time of oscillation (or of vibration) of the shorter one. \d^c physics. 53 228. The times of pendulums of the same length in dif- ferent places are inversely proportional to the square root of the intensity of gravity. 229. The Seconds Pendulum. — The length of the Pendu- lum performing its oscillations in seconds of time in the latitude of London (at the Greenwich Observatory) at the level of the sea is 39.13929 inches. At the equator its length is 39 inches, and near the poles it is about 39.2 inches. 230. The pendulum illustrates well the two kinds of energy — energy of motion and energy of position. When at rest the pendulum exhibits no energy whatever. But in raising the bob to one side, or elevating its center of gravity, we impart to it the ■potential energy (ox energy of position), which remains stored up as potential energy as long as we hold up the center of gravity, but becomes changed into kinetic energy (or energy of motion) as soon as we let it fall. 231. Potential Energy, then, is stored up energy, which is not doing work, but which has the ability to do work when- ever released. A body, as a weight, lifted up from the earth, being pulled downward by gravity, has the ability to fall as soon as its support is removed, and can then do work. The body of water in a dam has the power to move a water-wheel whenever allowed to fall upon it. A spring when wound up has power to turn machinery and to do other work. A stretched rubber band, a bent bow, also possesses potential energy of position. 232. Kinetic Energy, or energy of motion, or actual energy, is energy in the act of doing work. Thus it is the energy of the up-lifted weight after its support has been removed; of the water falling on the water-wheel; of the spring, of the stretched rubber band, and the bended bow, when released. 54 PHYSICS. CHAPTER XII. WORK AND MACHINES. 233. Units of Work. — In measuring work done the unit in which the work is expressed is the work done in lifting a given weight through a given vertical height. The English unit is the foot pound, which means the work necessary to raise one pound one foot; the metric unit of work is the kilogram meter, which means the work done in raising one kilogram through one meter. 234. But in order to estimate the power of any man, ani- mal or machine to do work, it is not enough to determine the weight which can be moved by each, and the distance through which that weight can be moved; it is also necessary to deter- mine the time required to do that work. 235. The work of carrying 100 pounds 100 yards is the same as the work of carrying 10 pounds i r ooo yards; and that work is the same whether it be done by a man, ahorse, or an engine, or whether it bedone by one man or several men; it is the same amount of work, too, whether it be done in an hour, a day, a week, or a year. But the rate of work can only be estimated by taking into account the total amount of work done by any given agent in a given time. The rate of doing work is usually expressed in horse-power. 236. It is assumed that a strong Horse is able to perform 33,000 foot-pounds of work in one minute; therefore that is the meaning of the term horse-power; thus 1 horse-power equals 33,000 foot-pounds per minute, and an engine of 20 horse-power is one capable of doing 660,000 foot-pounds of work per minute. 237. As the momentum of a body is the product of its mass by its velocity (203), and as a body gains accelerated velocity when acted upon by a constant force (223), it follows that when a body falls from a greater height it has greater momentum at the end of the time of motion. A weight dropped from a height of nine yards will strike a bed of clay with three-fold velocity and penetrate to nine times the depth into the clay as compared with the work of the same weight when dropped from a height of only one yard. The work done by a moving body will vary as the mass and as the square of the velocity. PHYSICS. 55 238. A machine is a contrivance by means of which a given power may be advantageously used to perform a given amount of work. 239. A Lever is an inflexible bar capable of being freely moved about a fixed point or line called the fulcrum at which the lever is supported. The power and the weight act on this bar at different points. A lever has two arms — the power-arm, and the weight-arm, separated by the fulcrum. 2 40. There are three kinds of levers, differing from each Fig. 56. A Balance. other according to the relative positions of fulcrum, power and weight. A" lever of 'the first kind" (see Fig. 56) has the fulcrum between the power and the weight, as in the steel-yard, or in a crow-bar, a balance, scissors, etc. A lever of the second kind has the weight between the power and the fulcrum, as shown in cork-squeezers, nut-crackers, tobacco-cutters, an oar, etc. A lever of the third kind has the power between the weight and the fulcrum, as in fire-tongs, sheep-shears, and in the treadle of a lathe. 241. The statical law of the lever. The product of the power 56 PHYSICS. multiplied by its distance from the fulcrum is equal to the product of the load multiplied by its distance from the fulcrum. Fig. 57. Cork Presser. A lever of the second kind. 242. Thus in a lever of the first kind, four feet long, if the load be one foot from the fulcrum, a power of one pound will balance a load of four pounds since 3x1 equals 1x3. 243. In a lever of the second kind four feet long with the load one foot from the fulcrum, a power of one pound will balance a load of four pounds, for in this lever the power will be four feet from the fulcrum. 244. With a lever of the third kind, of the same length as before, if the power be applied one foot from the fulcrum, a power of one pound will bal- ance a load of only one-fourth pound, for in this case the load is four feet from the fulcrum, and 1 x 1 equals 4 x 3^- 245. The Balance is a lever of the first kind (240), with two equal arms. (Fig. 56). The center of gravity of this lever must be a little below the edge of the fulcrum. This brings it to such a state of stable equilibrium, that it will readily return to a horizontal position. 246. A load carried on a lever be- tween two supports will be equally di- vided between the two carriers only if it be equidistant from the two points of sup- port. If, as shown in fig. 58, the load be placed only two feet from the first sup- port and four feet from the other, the load weighing thirty pounds, the first support carries twenty pounds of the load and the other only ten. Fig. 58. PHY5ICS. 57 247- A Pulley consists of a wheel turning upon an axis and having a cord passing over its grooved circumference. A single pulley as shown in fig. 5Q does not afford any increase of power but only a change of di- rection; but when two or more pul- leys are used together as shown in figs. 6o and 6i a greater load may be lifted with less power, but also with correspondingly less velocity. In the machine represented by fig. 6o it is evident that the hook supports one-half of the load and the hand pulls the other half up, but to raise the load one foot the hand must pull up two feet of the cord, for each section of the cord Fig. « F1ff.6c Fisr. or. carrying the load must be shortened one foot to raise the load" one foot. If the hand, therefore, lifts io pounds two feet, a load of 20 pounds will be raised one foot. With a combination of several pulleys the load which can be raised will be still greater in proportion to the power applied, and the ve. b which the load is raised will be proportionately lessened. 248. The Inclined Plane. — The power required to support a load on an inclined plane is to the load as the vertical height of the plane is to its length. Thus, if the plane is twice as long as it is high, a power of 100 pounds will support a weight of 200 pounds. 249. The Wedge is a movable inclined plane, or two inclined planes united at their bases. 250. The Screw is a cylinder with a spiral groove or ridge winding about its circumference. It is, in fact, s'mply a spiral inclined plane. The spiral ridge is called the thread of the screw, and this works in a nut in which there is a corresponding groove in which the thread fits One full turn of the screw will lift a weight through the distance which separates the threads. The weight moved is to the power required to move it, as the circumfer- ence described by the power is to the distance between the threads. 58 PHYSICS. Thus, a power of thirty pounds applied at the end of a lever two feet long, acting on a screw, the threads of which are ^ inch apart, will lift a weight of 45,300 pounds. Hence the great power of the screw press. 251. Friction is the resistance which a moving body en- counters from the surface against which it moves. A perfectly smooth surface can not be made, and despite lubrication and other means to diminish the resistance, heat is developed by the friction, and the mechanical energy is thus converted into molecular motion. Adhesion is doubtless closely related to friction. 252. Hydrodynamics is the dynamics (197) of liquids. Pneumatics is the dynamics of air and other gases. CHAPTER XIII. HYDRODYNAMICS. 253. Liquids transmit pressure equally in all direc- tions. — If pressure is applied from without upon water con- tained in a closed vessel, that pressure is transmitted by the water in every direction, upward as well as downward and out- ward, with the same force as originally applied. That force is proportional to the surface to which it is applied. Thus, if a pressure of one pound be applied to the water through a tube, the opening of which measures one square inch, then there will be a pressure communicated to the sides, top and bottom of the vessel amounting to one pound to every square inch of their surface. (See also paragraph 257.) 254. The Bottom Pressure. — Every molecule at the sur- face of a body of liquid presses upon the molecule next below it, and this next molecule not only transmits the pressure exerted by the upper molecule, but adds to that pressure its own weight, and so on downward through the whole depth of the liquid. The pressure thus increases with the depth, and if PHYSICS. 59 the liquid be contained in a cylindrical vessel with perpendicu- lar sides and horizontal bottom, the pressure upon that bottom is equal to the weight of the whole body of liquid. But in ves- sels contracted at the top the bottom pressure is greater, and in a vessel with a wider top the bottom pressure is less than the weight of the whole body of liquid, because the pressure depends upon the area of the bottom and the perpendicular height of the water without reference to the shape of the vessel. " Pressure percolators " of various kinds are constructed on this principle. 255. The Lateral Pressure. — As the pressure is trans- mitted equally in all directions (253) and at the same time added to in proportion to the depth of the liquid, the pressure on the sides of the vessel is equal to that exerted on the bottom of it only at the edge of the bottom. Midway between the bottom and the surface of the liquid the average pressure is only one- half as great as at the bottom, being always proportional to the depth. At the surface there is no lateral pressure because there is no depth there. 256. Liquids seek their own level. — When placed in com- municating-vessels, as in a U-shaped tube, liquids rise to the same level in the different vessels or in the several branches or tubes of the same vessel. As popular expression puts it: "water seeks its own level." Artesian wells operate on this principle, and " water towers " furnish the pressure by which water is supplied through pipes to whole cities, to high buildings and fountains in public parks. 257. The "Hydrostatic Para- dox." — Since the transmitted pressure is proportional to the surface to which it is applied (253), it follows that in a vessel with two communicating tubes, one larger than the other, both tubes being provided with tightly-fitting pis- tons, as shown in fig. 62, a downward -s 1 t Fig. 62. Hydrostatic Paradox. 6o PHYSICS. pressure applied upon the piston of the smaller tube will produce greater upward pressure upon the piston in the large tube, the pressure being proportional to the area. If the area of a be i square inch and that of b 16 square inches, then a downward pressure of i pound on (7 will produce an upward pressure of i pound to each square inch upon b, and I pound placed on the piston at a will lift 16 pounds on the piston at b (34). Fig-. 63. A Hydraulic Press. 258. The Hydrostatic or Hydraulic Press is based upon the principle explained in paragraph 257. The "Hydrostatic Press" (Brahma's Press) consists of two cylinders communicating with each other by a tube, as shown in fig. 63. The pump piston working in the smaller cylinder produces, by the arrangement of the valves below, a downward pressure which raises the large piston in the other cylinder. The distance of the upward movement of the larger piston will bear the same relation to the distance of the downward movement of the smaller piston as the pressure on the smaller bears to the pressure on the larger piston. If the area of the water pressing upward on the large piston be one hundred times as great as that of the water pressed downward in the smaller cylinder, the large piston will be raised only T ^ foot, while the small piston is pressed down a distance of 1 foot. Thus, on one side 1 pound is moved 1 foot, and on the other side a weight of 100 pounds is moved y^ foot, the work done being, therefore, the same on both sides (34.) PHYSICS. Hydraulic presses are much employed in the arts and manufactures, and may be seen in the laboratories of many manufacturing pharmacists and chem- ists, where they are used to press out liquids contained in wet masses of solid matter, etc. 259. The Law of Archimedes. — A body immersed in any liquid or gas is buoyed up [or pushed in an upward direction) with a force equal to the weight of its own volume of the liquid or solid in which it is immersed. This principle is one of great importance and wide applica- tion. The upward pressure produced by liquid and gaseous media, upon bodies immersed in them is termed the buoyancy of fluids. 260. In Fig. 64 we represent a cubical solid immersed in water. Every portion of the surface of the cube is subjected to the pressure which the body of water exerts in every direction, and which is pro- portional to its depth. The lateral pressure is equal on all sides (255), and therefore will have no tendency to move the solid in any horizontal direction. The pressure downward exerted upon the upper surface of the cube is, however, less than the pressure upward produced upon its under surface, because the pressure of the liquid increases with its depth (254). The exact difference between the downward pressure from above, and the upward pressure from below, is, in fact, exactly equal to the weight of a column of water having the same base and the same height as the solid (254). In other words, the upward pressure is greater than the down- ward pressure, by the weight of the liquid displaced by the solid. The solid, of course, displaces its volume of liquid. 261. Hence the principle of Archimedes is also stated as fol- lows: A solid immersed in any fluid {liquid or gas) loses in weight an amount equal to the weight of the fluid displaced by it. If a cubic inch of lead be weighed in a vacuum its true weight will be obtained; if it be weighed in air its apparent weight (45) will be less than its true weight (44) by the weight of a cubic inch of air; if it be weighed in water, its apparent weight will be still less, the difference from the true weight being now the weight of a cubic inch of water, which is heavier than a cub'c inch of air. 262. If the cubic inch of lead be weighed first in air, and then success- ively suspended and immersed in olive oil, oil of turpentine, glycerin, syrup, and sulphuric acid, the weights obtained will all differ from each other, because Fig. 64. •62 PHYSICS. all these substances differ in density (10) and specific weight (47) . The lead will accordingly be found to weigh as much less in olive oil than it weighed in air, as the weight of a cubic inch of olive oil; in the other liquids, the loss of weight of the cubic inch of lead will appear to be equal to the weight of a cubic inch of oil of turpentine, glycerin, syrup, or sulphuric acid, respectively. 263. There is, of course, no actual loss of weight of the solid in the examples given in the preceding paragraph, for matter can not lose weight. The so-called "loss of weight" is simply apparent, and instead of representing a loss of weight it repre- sents the effect produced by the buoyancy in the liquid or gas in which the solid is placed. 264. The Hydrostatic Balance. — A balance so con- structed as to facilitate the weighing of solids suspended in liquids is called a hydrostatic balance. One form of it is seen in fig. 55. At least one of the stirrups is short, and to the support for the pan is attached a little hook from which the solid is suspended by means of a thread or wire. 265. As all our ordinary weighing operations are performed in the air, and not in a vacuum, it follows that the results are not true, che weight found by weighing in the air being less than the true weight by the weight of the air displaced by the body weighed. 266. Our weights are constructed so as to show the " weight in air" and not " true weight," and it accordingly follows that a pound-weight made of brass is necessarily in reality heavier than a pound-weight made of plati- num, for the metal called platinum is about three times as heavy as an equal volume of brass, and, therefore, one pound of the alloy we call brass is about three times as bulky as platinum. Hence, when used in air, the brass pound and the platinum pound balance each other perfectly, or have the same weight (apparently), but if weighed in a vacuum the brass weight would be found to be heavier than the other. Had the brass weight been so made as to represent a pound of brass weighed in a vacuum, and the platinum weight to represent a pound of platinum weighed in a vacuum, then, when placed on the opposite pans of the balance (or " pair of scales") the platinum weight would go down and the brass weight up, and it would be necessary to increase the size of the brass weight or diminish the platinum weight to restore the balance to equilibrium. The saying that " a pound of feathers is heavier than a pound of lead," is, therefore, in one sense correct. PHYSICS. OJ 267. Heavy bodies sink in lighter fluids (whether liquids or gases), and light bodies float in heavier fluids. This will be readily understood upon a little reflection, for the upward pressure upon the immersed body caused by the buoyancy of the fluid is exactly measured by the weight the fluid displaced (259 and 260), and if that weight is less than the weight of the solid itself the solid will sink by virtue of its greater weight following the law of gravitation (38), but if the solid weigh less than its own volume of the fluid it must of necessity rise, or be pushed upward, or float on the surface of the fluid in which it is placed. 268. If the solid and the fluid in which it is immersed are of equal density, equal volumes having equal weights, then the solid will neither sink nor float but will remain at rest in any position in which t may be put in the body of the fluid. 269. Camphor floats on water, but sinks in alcohol. Wax floats on water, but if alcohol be gradually added to the water, the wax will sink as soon as enough alcohol has been added to render the density of the liquid less than that of the wax. 270. A floating body displaces its own weight of the fluid. — A piece of wood floating on water is depressed into the water just far enough to occupy a space below the surface which would be filled by its own weight of water. If the wood weighs one pound it sinks down far enough to push away, or displace, or occupy the space of one pound of water, below the surface. Boats displace their own weight of water; when empty the boat displaces but little water and rides lightly, but when loaded it sinks deeper as its load increases, and may be loaded so heavily that the weight of the boat with its load is greater than a body of water of the same bulk, and then the boat founders. 271. An "empty" bottle floats on water because the bottle and the air it contains weigh less than the same volume of water; but the same bottle, filled with water, sinks. 272. Since a floating solid sinks down just far enough to displace its own weight of liquid (270), it follows that the solid must descend to a greater depth in light liquids than in heavy liquids. 273. Hydrometers. — Hydrometers are instruments con- structed on the principle of Archimedes (259) and operates in accordance with the results of that principle as described in the preceding (270, 271, 272). 64 PHYSICS. 274. Fig. 65 represents Nicholson's hydrometer, consisting of a hollow metallic cylinder with a lead basket attached below and a pan supported on an upright wire at the top. The weight of the lead basket brings the center of gravity to that end of the instrument, causing it to descend some distance below the surface when placed in water, the hollow cylinder above being also a necessary feature of the apparatus, as it is lighter than water, and when pulled down by the lead therefore assumes a verti- cal position, the whole instrument thus remaining in a stable condition of equilibrium. The wire which supports the pan has a mark, A, upon it. As the hydrometer displaces its own weight of whatever liquid it is placed in, and its own weight is known, it is used in the following manner: The sum of the weight of the instrument, and the additional weights necessary to bring the instrument down to the point A, represents the weight of the liquid displaced. 275. Assuming that the hydrometer itself weighs 100 Grams and that it requires 55 Grams more to bring it down in distilled water until the surface of the water coincides with the mark A; also that it requires 20 Grams (instead of 55) to push the instrument down to A in alcohol. Then the displaced alcohol must weigh 120 Grams, and the same volume of water 155 Grams, and a comparison of the relative weights of equal volumes of these liquids has thus been effected. See " specific weight " (47). 276. Nicholson's hydrometer can also be used to find the specific weight (47) of solids insoluble in the liquid in which the instrument may be immersed. A piece of the solid substance (not heavier than the difference in weight between the instrument itself and the weight of the water it displaces to the mark A) is put on the pan at the top, and then enough additional weights added to push the hydrometer down to A in water; the solid is then removed and weights substituted for it to bring the instrument down to A again; the sum of the weights used in addition to the solid in the first case, deducted from the total of the weights used in the second case, must give the weight of the solid itself, or the sum of the weights which were necessary to take the place of the solid in the second experiment. Now the solid is put into the lead basket, and the hydrometer replaced in the water and again weighed down to A. As the volume of the instrument below the surface of the water is now increased by the bulk of the solid, the result will be that the instru- ment is buoyed up by an additional force equal to the weight of a volume of Fig. 65. Nicholson's Hydrometer. PHYSICS. 6S water equal to the bulk of the solid, and the instrument is at the same time pulled down by the whole weight of the solid. Suppose the solid weighs 7 Grams; then it will require 148 Grams additional weights to sink the hydro- meter to A (assuming, as above, that 155 Grams will be necessary to sink it to A in water); when the solid is placed in the lead basket, the instrument will not sink down to A without additional weights on the pan unless the solid is of the same density as water, it will sink deeper if the solid is heavier than water, and not as deep if the solid is lighter. Suppose it is heavier than water, and that it will, therefore, be necessary to take off some of the weights on the pan in order to bring the hydrometer to the fixed depth. If the sum of the weights on the pan be now 147 Grams, or one Gram less than was necessary when the solid was on the pan above the surface instead of in the basket immersed in the water, then the solid weighed 7 Grams in the air, but only 6 Grams under water, and, con- sequently, its own volume of water weighed I Gram. If the solid be lighter than water it must be tied to the lead basket before submerging it, and we should then find that 155 Grams would be insufficient to send the hydrometer down to the mark. Suppose, in such a case, it requires 156 Grams on the pan; then, the solid weighing 7 Grams, its own volume of water must weigh 8 Grams. 277. The common form of hydro- meter is shown in figs. 66 and 67. It is made of glass, the small bulb at one end is loaded with mercury or shot, and the expanded part of the tube above is to keep the instrument in an upright position. The hydrometer sinks to different depths according to the density of the liquid in which it is placed (270), and the point tO Which it Figs. 66, 67. Hydrometers. sinks in distilled water at the standard temperature is marked 1; 66 PHYSICS. specific weights above and below the unit are indicated on the scale. If the instrument is constructed to show the specific weight of any liquid, whether heavier or lighter than water, the unit (or the specific weight i) would be situated at about the middle of the stem, but a hydrometer for heavy liquids only has the unit at the top, and one for light liquids at the bottom of the scale. 278. There are several kinds of hydrometers (or areometers), some show- ing the specific weight, others with scales of arbitrary "degrees" of density, some for heavy and others for light liquids, and several kinds for other special uses, or for particular liquids, as alcohol, milk, syrup, urine, etc. CHAPTER XIV. PNEUMATICS. 279. The tension of gases. — We have already seen that molecules of gases repel each other (77). They, therefore, expand indefinitely if they find space to enter. Hence a small amount of the gas formed by the burning of a sulphur match soon spreads its peculiar penetrating odor through a whole room. The force with which gases tend to expand is called their tension (77). A liquid boils whenever the tension of its vapor is sufficient to overcome the atmospheric pressure, which always happens at the same temperature if the pressure is the same. 280. Gases are easily compressed. The resistance offered by the gas against compression is its tension. 281. Mariotte's Law. — The volume of a gas is inversely a s the pressure it sustains, at any given temperature. Thus if the pressure to which the gas is subjected be doubled, its volume of the gas is reduced one half; if the pressure be trebled the volume will be reduced to one-third; if the pressure be reduced one-half the volume of the gas will be doubled, etc. PHYSICS. 67 Gases under equal pressure expand equally for equal incre- ments of temperature (Charles). A given mass of gas, measuring one liter under the ordinary barometric pressure (287), will measure but one-half liter under the pressure of two atmos- pheres (287). 282. The densities of gases are in direct proportion to the pressure to which they are subjected (281.) 283. Atmospheric air is a mixture of about 79 volumes of nitrogen and 21 volumes of oxygen. It also contains small amounts of water vapor and carbon dioxide. Among the chemical changes which substances are liable to undergo when in contact with the air are, therefore: oxidation, the absorption of moisture when the air is humid; the loss of moisture when the air is dry, and the absorption of carbon dioxide. 284. Atmospheric Pressure. — The air, obeying the law of gravitation, exerts a pressure in every direction upon all bodies in contact with the terrestrial atmosphere. This pres- sure is equal to the weight of a column of liquid which it will sustain, and is very nearly equivalent to 15 pounds to each square inch of surface, or 1033 Gm. to each square centimeter. At the level of the sea the height of the column of mercury sus- tained by the atmosphere averages 29.922 inches or 760 milli- meters. As the atmospheric pressure is measured by the height of the column of mercury in the instrument called a barometer, we find the ordinary pressure generally referred to in terms such as "760 millimeters pressure," or "barometer at 760 m. m.," or " barometer at 30 inches." 285. When it is stated that the atmospheric pressure is equal to 30 inches by the barometer, the statement means that the weight of a column of air reaching from the earth's surface, at the level of mid-tide, to the upper limit of the atmosphere, equals the weight of a column of mercury 30 inches in height, the columns of air and of mercury being of the same area at the base. Hence it will be easily understood that the atmospheric pressure on high mountains, where the column of air is of less height, must be less, or must be balanced by a shorter column of mercury. It is further to be considered that the air is of greater density nearer the surface of the earth than higher up. At a height of 4.355 meters above the level of the sea, the barometric pressure is only 380 millimeters, or one-half the average pressure at the level, or the pressure of one-half atmosphere. 68 PHYSICS. 286. The amount of moisture contained in the air also effects its density and pressure. The barometer .rises with the humidity of the air, and falls when the moisture condenses and descends as rain or snow. As the humidity depends upon the temperature and movements of the atmospheric strata, the barometer indirectly indicates changes in the weather. 287. Atmospheric pressure is also called barometric pres- sure. The ordinary atmospheric pressure, balanced by a column of mercury 760 millimeters (30 inches) in height, is " the pressure of one atmosphere;" the pressure of twice as high a column of mercury represents "the pressure of two atmospheres," etc. 288. Weight of the Atmosphere. The atmosphere must weigh about six quadrillion tons, for it equals a layer of mercury covering the entire surface of the globe to the depth of 30 inches, and the specific weight (47) of mercury is 13.6. The air in a room 12^ feet long, 10 feet wide and 10 feet high weighs nearly 100 pounds. 289. But the pressure of the air, which amounts to about 15 pounds to the square inch, is not a dow?iward pressure. As in the case of liquids it is a pressure distributed in every direction. (253 to 255.) All bodies on the earth's surface sustain this pressure. The human body, which has a surface of about 2,000 square inches, must, therefore, sustain a pressure equal to about 15 tons, but we do not feel it because it is precisely what is required for our well-being. Were this pressure to be removed the result would be destructive to us. 290. The weight of a body is in no degree added to by the pressure of the atmosphere. In fact, we have already learned that all bodies are pushed upward when surrounded by, or immersed in, the air. 291. The Barometer. — Figure 68 represents an instrument called a barometer. It is designed to indi- cate the atmospheric pressure. The tube, closed at one end, is filled with mercury and then inverted in a vessel also containing mercury. In the ordinary barometer the lower end of the inverted tube is expanded and bent upward, which renders a Fig. 68. separate vessel for the mercury superfluous. The mer- 'HYSICS. 69 cury runs out until the column remaining in the tube measures 29.922 inches, or 760 milimeters. This proves that a column of mercury of that height balances a column of air of the same diameter reaching through the whole atmosphere from the level of the sea as far up as the atmosphere reaches. 292. Height of the Atmosphere. — It was formerly sup- posed that the atmosphere was about 45 miles high ; but it is now considered probable that it is at least 100 miles. But, as the height of the mercury of the barometer is only 15 inches when the instrument is taken upon a mountain 3^ miles above the level of the sea, it follows that one-half of the whole ocean of air contained in the atmosphere must lie within a distance of 3^ miles from the earth's surface. 293. A column of water equal to the atmospheric pressure would measure 34 feet, the mercury being 13.6 times as heavy as water. 294. The pneumatic inkstand, represented by fig. 69, operates upon the principle that the atmospheric pressure sustains the ink in the inkstand. Whenever the ink in the tube of the bottle comes below the level of the curve a bubble of air enters and forces a portion of ink out into the tube. Fig. 69. 2 95- Fig. 7° a ^ so illustrates the pressure of the atmosphere. If you place a thick sheet of paper over the top, pressing down the paper tightly, and then cautiously invert the tumbler, the water will not run out because the atmospheric pressure upward keeps the paper in its place and prevents the entrance of air into the tumbler. 296. In a Pipette, which is the name of the instrument shown in figs. 71 to 75, the atmospheric upward pressure prevents the liquid in the tube from running out. fill a tumbler with water and 7 o PHYSICS. Plunge the instrument into a vessel of water, holding the long tube vertically; when the bulb is filled, close the upper end with the finger, and then withdraw the pipette out of the vessel. The water remains in the pipette. Now take the finger off the upper end of the tube so that air can enter; there will then be atmospheric pressure from above as well as from below, and, consequently, the water will run down by its own weight. 297. The Siphon. — Another very useful instrument, operat- ing by atmospheric pressure, is the familiar siphon. It consists of a bent tube, open at both ends, with one limb longer than £ * Fig. 76. Fig. 77. the other. The tube may be rigid, as when made of glass or of wood or metal ; or it may be elastic, as when consisting of rubber hose. If the short limb be immersed in a vessel of liquid and the whole tube filled with liquid by suction at the end of the longer limb, the weight of the liquid in both limbs would tend to cause a downward flow; the atmospheric upward pressure would prevent the liquid from running out if both limbs of the syphon were of the same length; but as one limb is longer the weight of the liquid in that limb is greater than that of the liquid PHYSICS. 71 in the other limb, and hence the liquid in the longer limb descends while the atmospheric pressure upon the liquid in the vessel forces the liquid up into the shorter limb, since otherwise there would be a vacuum in the siphon, which can not be. 298. To start the syphon it may be filled with the liquid, both ends being closed with the finger ends before placing it in its position, with the short limb in the vessel containing the liquid and the longer limb in the vessel into which the liquid or a portion of it is to be transferred. 299. The syphon will continue to run until the level of the liquid in the vessel in which the shorter limb is placed descends below the end of the tube, or until the level of the liquid in both vessels coincide should they be so placed as to lead to that result. The end of the limb from which the liquid flows must always be below the surface of the liquid in the vessel from which the current comes. 300. Wash bottles are made as represented by figs. 78 and 79. Air is blown into the bottle through the tube A and the pressure thus brought to bear on the surface of the water causes a stream to flow through B. Any ordinary wide-mouthed bottle, with a well-fitting stopper twice perforated for the glass tubes, may be used. The end of the glass tube B should be drawn to a point so as to contract its orifice enough to produce a small stream. Figs. 7 8 and 79. 301. Atomizers consist of two tubes placed in such a position relative to each other that a jet of air blown through one of them passes over and near the mouth of the other. One is the blast tube, the other the suction tube dip- ping into a bottle of liquid. A strong current of air blown through the blast tube carries the air along its path with it so as to cause a rarefaction in the other tube, diminishing the atmospheric pressure in it so that the atmospheric pressure in the bottle will raise the liquid to the mouth of the tube where the current of air from the other tube will blow it into fine spray. 302. Vacuum. — Space void of water is called vacuum. The space above the mercury in the barometer tube is the most per- PHYSICS. feet vacuum that can be produced- it is called the Torricellian vacuum . But a closed vessel may be deprived of nearly all the air it contains by means of an air pump, and in certain pharmaceutical processes a vacuum appa- ratus, vacuum pans, etc., are employed with the view to remove atmospheric pressure and to avoid the chemical charges liable to result from contact with the constituents of air. 303. The Air Pump. — Fig. 80 represents an apparatus for removing the air from a closed vessel,, the sections of its principal parts being shown in fig. 81. . "The receiver, R, is connected with the cylinder, C, by a long bent tube, terminating in a horizontal brass plate. The mouth of the receiver and the surface of the brass plate are carefully ground so as to bring them in contact at every point. The edge of the receiver is greased, so as to make the joint as tight as possible." "When the piston Pis raised from the bottom of the cylinder, the external air closes the upper valve; the air in the receiver ex- pands, opens the lower valve and fills the cylin- der. When the piston is depressed, the lower valve closes, and the air in the cylinder is forced through the upper valve out into the atmosphere. As the Fig. 80. Air Pump. piston again rises, the up- per valve is closed, the lower valve opens and the confined air expands into the cylinder. At every ascent and descent of the piston, a portion of air is removed from the receiver, and this process may be repeated until the ten- sion (279) of the air remaining is not sufficient to lift the lower valve. The receiver is then said to be exhausted." PHYSICS. 73 SO Ht^L^- Fig. 81. "The tension of the air in the receiver is measured by a gauge which consists of a bent tube leading from the receiver to a vessel of mercury, H. The external air forces the mercury up the gauge in proportion as the tension of the air in the tube is diminished. If the exhaustion were perfect, the mercury would rise to about 30 inches. The height of the gauge indicates the difference between the pressure of the atmosphere and the tension of the air in the receiver." "The air pump is also provided with a stop cock, S, fig. 81, to close the communication between the cylinder, and receiver when required. The stopper, A, is used to admit the external air to the receiver. A third valve, T, is usually placed in the top of the cylinder to prevent the external air from pressing on the piston." 304. The Magdeburg Hemispheres are two hollow brass hemispheres fitting together by an air tight joint, as shown in fig. 82. When joined together, the air can be exhausted from the globe by means of an air pump. The hemispheres will now be pressed together by atmospheric pressure, or with a force of 15 pounds to the square inch. With a diameter of three inches, the area of the section would be seven inches, and hence it would require a force of over 100 pounds to pull the hemispheres apart. Fig. 8s CHAPTER XV. THEORIES AND SOURCES OF HEAT. 305. Heat is that mode of molecular motion which may be measured by the expansion of bodies, or which manifests itself, under certain conditions, by the sensations of " warmth" and "cold." 306. "Heat" and "cold" are only relative terms. A room, the atmos- phere of which seems " hot" to one person, may seem chilly to another. If you hold one hand in cold water and the other in hot water, and then sud- denly transfer both hands to water which is neither hot nor cold, you will find the sensations in your hands reversed. Therefore, cold is not the oppo- site of heat, but only a lower degree of heat. 307. That heat is a mode of motion is now the universally accepted 74 PHYSICS. theory. Nevertheless, a definition or description of what heat really is, or what distinguishes it from other modes of molecular motion, is far more diffi- cult than to describe what heat does. 308. Heat expands bodies, or increases their volume, or reduces their density, or overcomes their cohesion, or increases the distances between their molecules— all of which statements mean the same thing. This effect of heat is resisted by cohesion (55), and may also be opposed by pressure. 309. When heat is applied to any substance a portion of that heat increases the temperature (313) of the suostance, while another portion increases its volume, and may, if a sufficient quantity of heat is adduced, turn solids into liquids and liquids into gases. 310. Active heat, or sensible heat is that heat which increases the temperature of bodies and has the power to cause their expansion. It produces upon men and animals the impres- sion of " heat " if the heat motion is rapid, or of " cold " if the motion be less rapid. Having the power to expand bodies it causes the mercury in the thermometer (321) to rise. It is energy in ihe kinetie form (232). 311. Latent Heat is that heat which has performed the work of expanding the volume of matter and which keeps up this expansion. It performs " interior work " in separating the molecules of the body from each other, and while performing that work can not at the same time do other work, and it, therefore, can not cause the mercury in the thermometer to rise- Latent heat is a form of potential energy (231). Heat rendered latent is, of course, not lost or destroyed (34 and 67). It can be released again, or recovered, in precisely the same amount of energy, or as active heat, by the compression of the body it expanded. 312. If a quantity of broken ice be placed in a dish and the dish placed ever the fire, the ice will melt, but a thermometer placed in the mixture of water and ice will not vary its indication of temperature; the mercury will remain at zero C. (32° F.) until all the ice has been melted. If the heat be contin- ued the temperature of the water will now, since the ice has all been melted, rise until it reaches ioo c C. (2I2 C F.), and there it will stop again: the water will now boil and the temperature will remain stationary until the water is vaporized. PHYSICS. 75 and the vapor formed will be found to have the same temperature as the boil- ing water. Why does not the fire under the vessel warm the contents above o° C. until after all the ice is melted? Why does it afterwards raise the temperature of the water rapidly up to ioo° C. and no further? Because all the heat communicated to the ice was utilized in performing the interior work referred to in the preceding paragraph and therefore could not at the same time increase the temperature of the ice (solid water); but the heat afterwards communicated to the water did not do any interior work but. raised the temperature instead until the boiling point was reached. At the boiling point the water could no longer exist in a liquid state, because the ten- sion of its vapor at that temperature is greater than the atmospheric pressure and the continued application of heat, therefore, resulted in the vaporization of the water, all the heat now communicated doing " interior work" again in overcoming cohesion (55). 313. Similar results follow the application of heat to other solids and liquids. Any given solid always melts at the same temperature if the pressure be the same. Any given liquid always boils at the same temperature, provided the pressure be the same. Hence any given fusible solid hastits own specific melting point (376); any given vaporizable liquid has its own specific boiling point (392); and any vaporizable solid, which does not melt before it vaporizes, always volatilizes at the same temperature. But different substances generally have different melting points, different congealing points (381), and different boiling points. 314. Temperature. — The intensity of heat is called tempera- ture. It is measured by the expansion it produces in the vol- umes of bodies (320). The molecules of all matter are in continual motion, and all bodies have heat. Increased intensity of heat motion means a higher temperature, and slower molecular motion means a correspondingly lower temperature. 315. The old theory of heat regarded heat as " imponder- able matter," or matter without weight. But there can be no matter without weight, for matter i( ^£^3g else but that which is weighable. It was thought that turning a solid into a liquid by the w I of heat was to add heat to the solid, the result of this union of two things I -r-ng a liquid; and that by adding more heat to the liquid a gas was produced. I.t was further said 76 PHYSICS. that the gas could be turned into a liquid again by taking away heat from it, and that liquids were turned into solids in the same way. The strongest confirmation for this theory was the fact that when bodies are reduced in volume by pressure, heat is generated. It looked as if heat could be squeezed out of the matter. But the " sensible "or " active " heat which makes its appearance when the volume of a body is diminished by pressure is pre-existing energy mani- festing its presence by new phenomena. 316. The Sun, which is the source of all the energy of the life of plants and animals, and of nearly all the energy employed in mechanics, is also the greatest source of heat. It is the first source of most of the available heat of the globe. The total heat emitted by the sun is two thousand one hundred and twenty-nine million times that which reaches our earth. The Jixed stars also send radiant heat to the earth. As our vast coal beds are formed from vegetable growths, they represent stored up potential energy derived from the sun. Heat is also stored up in the interior of the earth. 317. Friction, percussion and compression produce heat. Fire may be produced by rubbing two pieces of wood against each other; savages produce fire in that manner. The composition on the end of matches ignites by comparatively light friction. If you rub a piece of metal against a stone it gets hot. A piece of steel held against a rovolving dry grindstone not only gets hot, but sends incandescent particles of steel flying from it. A piece of wrought iron may be hammered until red hot. A single blow explodes a mixture of potassium chlorate and sulphur, and the composition in a percussion cap. A piece of tinder fastened to the end of the piston of a strong glass syringe may be ignited by suddenly driving the piston into the tube; this result is caused by the great amount of heat liberated when the air is compressed. 318. Chemism also produces heat. Whenever any two kinds of matter react upon each other chemically (319), hest is evolved. The amount of heat thus liberated is constant for any given reaction. Electricity is also generated by chemical action, and heat may be also produced by electricity. 319. Combustion is chemical action, and is one of the main direct sources of heat available to man. But heat is liberated in very large amounts, even by chemical reactions, which are not accompanied by flame or light, as when diluted sulphuric acid and water of ammonia are mixed, or when lime is slacked by pouring water upon it. But the relatioHS of heat to chemism will be referred to again further on (514). 77 PHYSICS. CHAPTER XVI. THERMOMETRY. 320. Temperature (314) is measured by instruments called thermometers. These are so constructed that the expansions and contractions caused by changes in the temperature can be easily seen and expressed. The substances most used aa indicators are mercury, alcohol, metal and air, all of which respond readily and sufficiently regularly to the changes in the velocity of heat vibration. 321. The mercurial thermometer, which is so universally employed, is constructed as follows : It consists of a glass tube of extremely fine calibre — a capillary canal — expanded at its lower extremity into a bulb (fig. 83). The bulb and part of the tube are filled with pure mercury, after which the air is carefully expelled and the upper end of the tube closed. The instrument is then inserted into pounded ice, and the point at which the top of the mercury then stands is marked. The next step is to suspend the tube in the steam rising from pure boiling water in such a way that it is completely surrounded by it. This causes the mercury to rise in the tube until it reaches a certain point at which it stops and remains fixed. This point is also marked. The interval between these two points is now graduated into 100, 180, or 80 equal spaces (or intervals, called degrees) according to whether the scale is to be that of Celsius, Fahrenheit, or Reau- mour. The scale of degrees is, therefore, based upon the melting point and boiling point of water. 322. The Centigrade Thermome- ter. — The thermometer scale devised by Celsius (Fig. 85) is deservedly esteemed the most simple, rational, and worthy of universal adoption. It is called the centi- grade thermometer because the interval be- tween the melting and boiling points of water is divided into one hundred degrees (or equal spaces). The scientific simplicity -212 -192 -172 -152 -132 -112 -92 -72 -52 ■32 Figs. 83, 84, 85. IOC' 80 60 '0 20 78 PHYSICS. of this thermometer as compared with others has led to its almost universal employment in science. Although Fahrenheit's thermometer (325) is the one in general use for ordinary purposes in the United States, the centigrade thermometer is used by our chemists and in the Pharmacopoeia. 323. On the centigrade scale the freezing point (or, rather, the melting point) of water is denominated zero (= o° ), and the boiling point consequently + ioo°. The degrees above zero are the positive (+) degrees, and those below it, which are made of equal length on the scale, are called negative ( — ) degrees. 324. On Reaumour y s scale the freezing point is also zero, or o°, but the boiling point is + 8o°. Thus four degrees R. are equal to five degrees C, and C.° : 100 :: R.° : 8o°. In order, therefore, to convert any number of degrees R. to the corres- ponding number of degrees C, multiply by \; and to convert from C. to R., multiply by f . 325. Fahrenheit's thermometer (Fig. 84), which is almost exclusively used by the people of the United States and Great Britain, has the freezing point marked + 32 , and the interval between this point and that at which water boils is divided into 180 equal spaces (instead of 100 as in the centigrade thermome- ter). Thus + 32 F. equals + o° C, and ioo° C. equals (32 4- 180 = ) + 212 F. Nine degrees on Fahrenheit's scale occupy the same distance, relatively, as five degrees on the centigrade scale. But to convert F.° into C.° it will not answer to multiply the number of degrees F. by 5-9 until after 32 has been deducted from the number, for C.°: 100: : (F.° — 32) : 180, or gC.= 5 (F — 32); and in converting C.° into F.° the number of degrees C. must first be multiplied by 9-5, and then 32 added to the product. The rule, then, for reducing thermometric degrees from C. to F. is Multiply by q 5 and add 32, and the rule for reducing Fahrenheit's degrees to Centigrade is Deduct 32 and jnultiply the remainder by j-o. 326. Mercury thermometers are made to indicate temperatures from — 30 F. to -f- 6oo° F. At very high temperatures, however, the scales are liable to vary from each other somewhat, for want of an unexceptionable natural physics. 79 ft standard by which they may be corrected. When sealed at the top a good mercury thermometer can not be made to indicate temperatures above +580 F., as the mercury may boil above that point. But the most accurate instrument indicates correctly only degrees between — 35 C. and a little over -f- 200 C. 327. As the freezing point of alcohol is much lower than the freezing point of mercury alcohol thermometers (or " spirit thermometers") are used for measuring very low temperatures. The alcohol in the tube is usually colored red so that the readings may te easier. 328. Pyrometers are metallic thermometers, or instruments by which temperature is measured by the linear expansion of bars of metals. They are of various forms, but their indications are very uncertain. 329. Air thermometers are very sensitive, and the most reliable thermometer known is Regnault's air thermometer; but it is too com- plicated to be described in such a book as this, and is used-only for special scientific determinations and comparisons. 330. Laboratory thermometers used for measuring high temperatures of liquids, in chemical and pharmaceutical work, are constructed somewhat differently from those intended for ordinary purposes. They are long and slen- der, of exceedingly fine bore, and have very small bulbs (Fig. 86). The advantages gained by these conditions are that the divisions on their scales are larger and, therefore, Fig. 86. more accurate, and the instrument readily attains the temper- ature of any liquid in which it is plunged, without materially affecting it. Small thermometers — slender tubes of small inter- nal diameter — are, as a rule, more accurate than larger ones. 80 PHYSICS. CHAPTER XVII. ABSOLUTE HEAT AND SPECIFIC HEAT. 331. Absolute Heat and Specific Heat. — It has been shown (321) that the arbitrary degrees of temperature indicated by all thermometers are based upon the constant temperatures of boiling water and melting ice under the pressure of one atmosphere. But these degrees do not tell us how much heat a body con- tains. Thus the zero point does not indicate absence of heat, nor does a tem- perature of 100 indicate that a body at that temperature contains 100 times as much heat as it contains when at i°, nor that boiling water is twice as hot as water at 50°. Bodies have been cooled to — 220° F. without reaching the absolute zero (332). 332. Absolute Temperature. — Air and other gases ex- pand uniformly with equal increments of temperature (364). Air thus expands to the extent of -^-3 of its volume for every added degree according to the centigrade scale. Therefore air of _|_ 273 C. occupies twice as much space as is occupied by the same amount (by weight) of air at o° C. Below zero the vol- ume of the air is diminished in the same ratio, so that if it be cooled to — 273 C. its volume must theoretically be reduced to nothing provided it remains in a gaseous state; but the air becomes a solid long before that temperature is reached, and it would then no longer obey the law of Charles (333). It is assumed, however, from the foregoing, and for other more conclusive reasons, that at — 273° C. all bodies become entirely devoid of heat. That point is, therefore, called absolute zero, and temperature counted upward from absolute zero is called absolute temperature. On this scale all temperatures would be positive (323.) 333. The law of Charles is that the volume of a given mass (7) of gas at constant pressure is directly proportional to its absolute temperature. PHYSICS. 8l 334. The Specific heat of a body is the ratio of its capac- ity for heat as compared with that of an equal volume of water. As water is the standard comparison the specific heat of water is of course 1, and the specific heats of the other bodies are expressed in water units, just as specific weights are also expressed in water units. 335. Thermal Units, or heat units. — The amount of heat necessary to raise the temperature of one kilogram of water one degree C. is called the unit of heat, or thermal unit. It follows that the number of thermal units necessary to raise the tem- perature of any given body one degree expresses the specific heat of that body. (Heat units are also sometimes called calorics.) 336. The temperatures of equal masses of different sub- stances are not raised equally by equal amounts of heat. If equal weights of mercury, alcohol and water are exposed to the same heat, the mercury will rise 30°, while the alcohol rises 2° and the water i°. In other words, it requires 30 times as much heat to raise the temperature of water one degree as it takes to raise the temperature of the same quantity of mercury one degree ; and it takes twice as much heat to raise the temperature of a kilogram of water from o° to i° C. as is required to raise the temperature of a kilogram of alcohol from zero to i° C. 337. But the specific heat of all solids and liquids, and of most of the gases, increases slightly with the temperature. Thus water at o J C. has the specific heat 1 ; water at 40 C, 1.0013 ; at 8o c , 1.0035. Liquids usually have a higher specific heat than solids and gases. The specific heat of water is almost double that of ice, and a little more than twice the specific heat of steam. 338. Water possesses a greater capacity for heat than any other sub- stance except hydrogen. It requires more heat to warm it, and gives out more heat in cooling through a given range of temperature. The same quantity of heat that raises the temperature of one kilogram of water from o' C. to ioo° C. heats one kilogram of iron from o° to 8oo° or 900 C, or above red heat. 339. The heat lost in cooling is precisely the same amount as is required to raise the same body through the same number of degrees. Therefore, when equal weights of different substances are heated to the same temperature and then placed on ice, the amount of ice melted will be in proportion to the number of thermal units they contain. If a given weight of 62 PHYSICS. boiling water will melt one pound of ice, an equal weight of sulphur of ioo° C. will melt ^, iron ^, and mercury ■£$ of a pound of ice. 340. If one kilogram of water at ioo° C. be mixed with the same quantity of water at o° C, the temperature of the mixture will be Aoo|>oil = 5 o° C. Thus the heat lost by the boiling water is precisely the same amount as that gained by the ice water. But this simple result does not follow when different substances are mixed. 341. The high specific heat of water explains why the vicin- ity of large bodies of water produces such a decided effect in moderating climate. Lake Michigan makes the summers of Chicago cooler, and its winters warmer. CHAPTER XVIII, DISTRIBUTION OF HEAT. 342. Distribution of Heat. — Heat may be conveyed from one body to another not only when they are in contact, but also when there is a distance between them. In the former case the heat is transmitted either by conductio?i or by convection; in the latter by radiation. 343. Conduction. — If a piece of metal be heated at one point, we may readily observe that the heat gradually spreads throughout the whole mass. The same transmission of heat takes place when two bodies of different temperatures are brought into intimate contact with each other; the temperature of the colder body increases, while that of the warmer decreases, until both have attained the same degree (382). This is called the conduction of heat, and the heat motion is communicated from molecule to molecule. 344. The rapidity with which heat is conducted from mole- PHYSICS. 8$ cule to molecule varies in different substances; but the ten- dency to an equalization of temperature is universal. Any body having a higher temperature than surrounding bodies, will sooner or later impart to them some of its heat, until all have attained the same rate of molecular vibration. 345. The power of any body to conduct heat is generally proportional to its density. Metals and stones are good con- ductors of heat; they quickly become heated, and as quickly cooled, and are commonly designated as cold bodies. Porous substances, like wood, wool, cotton, are poor conductors of heat; they are less readily made hot, retain their temperature longer than the good conductors of heat, and are called warm bodies. Liquids and gases are almost non-conductors. Feathers, fur, and wool owe their non-conducting properties largely to the air confined between their fibres and meshes. 346. The conducting power of a body may be judged of to some extent by the sense of touch. In cold weather stones and metals feel colder to the touch than glass, resin, wood, water or air, and in the summer the same stones and metals feel hotter than the other objects. Oil cloth on the floor is colder in winter and warmer in summer than a woolen carpet. 347. Cooking utensils, such as kettles, pans, etc., and the vessels used by pharmacists and chemists for heating liquids, are made of good conduc- tors of heat, such as metals, as far as practicable. Earthen ware, porcelain and glass are used for these purposes only, because many substances attack metals and are themselves affected by contact with metals. Silver has a very high thermal conductivity, and copper is also an excel- lent conductor; iron is far inferior to either. 348. Poor conductors are extremely valuable, both as a means of preventing the escape of heat, and to exclude heat. Thus, if a vessel containing a hot liquid or vegetables put in boiling water, be covered and placed in a wooden box lined with felt, and the box tightly closed, the high temperature will be retained for many hours. Shrubs and plants are wrapped in straw to prevent the escape of their heat. Snow pro- tects vegetation from the extreme cold of winter. Furnaces would be useless without the fire brick which, being made of non-conducting material, retains the heat. Clothing keeps the heat of our bodies in and keeps the cold of the air out. Animals in cold regions are protected by their fur and down. 349. Convection is the transmission of heat vibration by the motion of masses of molecules in currents. 84 PHYSICS. Convection, therefore, occurs only in liquids and gases, in which currents are possible. It depends upon gravitation. Hot or warm liquids and gases are lighter or less dense than colder liquids or gases; and lighter fluids rise to the top while the denser fluids sink to the bottom. If, therefore, heat is applied under a kettleful of water, that portion of the water, which is first heated will rise to the surface, while other portions of water take its place, and currents are thus established in the liquid, which materially aid in diffus- ing the heat through the whole mass. A fire in a grate heats the air above it and the heated air rises through the chimney, while a new supply of air takes its place creating a draft. 350. In all cases where currents are thus established in fluids by the application of heat at the bottom of the liquid or gas, the currents are in opposite directions, the heated fluids rising upward while the cooler portions flow in downward currents. The lower strata of air are warmed by the earth and then rise, the colder strata descending to take their place. Moreover, as the earth is not heated equally in all places, horizontal currents are established in opposite directions, which we call winds. 351. Ventilation is intimately connected with the convec- tion of heat and the opposite currents established by it. Venti- lation is the removal of vitiated air from rooms, shops and other, confined spaces, and the supplying of fresh air to take its place the object being to maintain the atmosphere in a state of purity. In apartments occupied by men or by animals the air becomes vitiated by respiration, the oxygen of the air being consumed, carbon dioxide taking its place. An adult man inhales about fourteen cubic feet of air per hour; but it is not enough that the amount of air in the apartment be sufficient for the inhalation of fourteen cubic feet per hour. The air inhaled must be pure at any and all times, and this requires a constant supply of fresh air and a con- stant escape of the vitiated air. The combustion of oil or gas for illumination also consumes oxygen, and thus vitiates the atmosphere of a room. When a window is opened to produce a change of air, it should be opened at the top, because the cold, fresh air entering near the ceiling diffuses through the whole room, while the foul, airbeing warm, escapes. The air in a room is warmest at the ceiling. Hence, in a drug store, sub- stances which are liable to be injured by the higher temperature in the upper strata of the atmosphere of the room should not be kept on the top shelves. 352. Radiation of heat. — The heat which is diffused through space from the sun reaches the earth by radiation. PHYSICS. 85 353. In order to be able to explain or understand how heat and light can be received by us from the sun, it is necessary to assume that the space which separates the terrestrial atmosphere from the sun can not be empty, for motion can not be communicated by nothing or through empty space. It is, therefore, assumed that there is a medium, which has received the name of ether, capable of communicating motion, and occupying all of the otherwise unoccupied space in the universe. Ether is accordingly supposed to pene" trate between all molecules of matter. Ether is not matter; it can not be weighed nor measured. It can not be seen, heard, felt, tasted nor smelled. But its existence is assumed because the phenomena occurring in nature can not be accounted for on any other supposition, while they are explainable on the hypothesis that an ethereal medium exists which is capable of transmit- ting motion. These phenomena occur in just such a manner as they must occur if all space were filled with such a medium. 354. Sound, light and heat are transmitted through the medium of ether, and are, therefore, referred to as forms of radiant energy. They are commu- nicated by a wave-like, vibratory motion, and this theory of wave-action is called the undulatory theory. All the phenomena of light and of radiant heat show a remarkable analogy. 355. Heat radiates in straight lines in all directions, and the intensity of radiant heat is inversely as the square of the dis- tance from its source and proportional to the temperature of that source. 356. Different bodies vary greatly in the power of emitting radiant heat. Lamp black has the highest radiating power known, and polished metals are the poorest radiators of heat. A bright silver tea-pot filled with hot liquid retains its temper- ature longer than one of earthenware. Steam pipes for heating buildings should be kept bright until they reach the rooms where the heat is to be diffused; there they should be coated with lamp black to increase their radiating power. 357. Heat is reflected by all substances which are good reflectors of light. Thermal rays are also refracted like rays of light, but the thermal rays are of different refrangibility and wave length (412). Transparent bodies generally transmit heat as well as light from the sun, but they do not transmit equally the heat rays from artificial sources. 86 PHYSICS. The heat from the sun warms the room through the window-glass, but the same thickness of glass intercepts the heat from the fire-place. Different substances transmit heat unequally, and absorb heat unequally. Heat rays which are absorbed increase the temper- ature of the bodies which absorb them; rays which are trans- mitted or reflected do not warm them. CHAPTER XIX. THE EXPANSION OF BODIES BY HEAT. 358. The first and universal effect of heat upon most bodies is to increase their volume (309). This expansion of a body by heat is the result of a widening of the dis- tances between the molecules of the body. Heat motion increases the iuter- molecular spaces, and thus overcomes cohesion. 359. Numerous easy experiments might be described here to prove that heat expands matter; but you can doubtless invent some yourself, and I will, therefore, only refer to a few familiar examples. The mercury or alcohol in the thermometer (320) expands with an increase of temperature, and contracts with a reduction of it. The rails of a railroad are of necessity laid in such a manner that their ends are not in actual contact even in hot summer weather; if they were laid without any space between their ends they would expand under the influence of the heat from the sun so as to bend out of shape. In cold weather there is considerable space between the ends of the rails. A metal ball or cylinder which, when cold, passes through but nearly fills a metal ring will not pass through if heated. If you fill a tin cup to the brim with cold water and set it on a hot stove the water will run over when it becomes warm. If a glass stopper has been inserted into the neck of a bottle so tightly that it can not be removed in the usual way, you can loosen it by warming the neck of the bottle, for as the neck of the bottle expands the stopper will, of course, no longer fill it so tightly. PHYSICS. 87 [In doing this remember that only the neck of the bottle is to be expanded and not the stopper, for if you heat the neck so long that the heat is trans- mitted to the stopper, too, both will expand. Moreover, take care that the heat be applied cautiously so that the glass may not break (365). The neck of the bottle may be heated by friction (317), which is easily applied by pull- ing back and forth a cord tightly wound around it. 360. Force of Expansion and Contraction. — Water expands for each degree F. with a force equal to ninety pounds to the square inch; i. e., it would require that amount of force to resist its expansion when its temperature is increased one degree. To compress boiling water back to its volume at the freezing point would require a pressure of one thousand atmospheres, or a layer of mercury almost half a mile thick. 361. The expansion of solids and liquids by heat is unequal. Gases, however, expand equally and uniformly (364); under equal pressure their volumes increase in the same ratio with equal increments of temperature, and at equal temperature their volumes are inversely as the pressure which they sustain (Boyle, Mariotte and Charles). Gases, when their temperature is raised, expand more than solids and liquids. 362. Linear expansion (or linear dilatation) is expansion in one direction only, as when a rod or an iron rail is lengthened by an increase of temperature. 363. Cubical expansion (or cubical dilatation) is expansion of volume. Solids, liquids and gases are all subject to cubical expansion and contraction as their temperature increases or decreases. 364. Co-efficients of Expansion. — By "co-efficient of expansion " is meant the number which expresses the measure of the expansion of a body when its temperature is raised one degree. The ratio of expansion for gaseous bodies is 0.003663 (or -g^-j) of their bulk for each degree C, or 0.002037 (or ^V.-g) for each degree F., above the freezing point of water. This means that the bulk of a gas is increased by 0.003663 (or -^-j) 8S PHYSICS. when its temperature is increased one degree by the centigrade thermometer, and by 0.002037 (or j^ i7 ) when it is raised one degree by Fahrenheit's scale. In the case of solids and liquids the ratio of expansion increases as the temperature rises. 365. Unequal expansion by heat often results in the fracture of brittle solids', that danger is greater the thicker the solid is, and greatest when the thickness is unequal. Cast iron and glass, when suddenly heated, are liable to crack, because the side to which the heat is applied expands more rapidly than the other side. Sudden cooling has the same effect by causing unequal contraction. Thick vessels of glass, porcelain, wedgewood ware, etc., like graduates, mor- tars and bottles, and especially vessels of unequal thickness, are frequently cracked by carelessly heating or cooling them suddenly. Do not pour hot liquids in cold glass or eathenware vessels nor cold water in the same vessels when hot, and do not put a hot dish on a cold surface nor a cold one on a hot surface. 366. Expansion of Water. — Water forms the only excep- tion to the rule that bodies expand whenever their temperature is increased, and contract whenever the temperature is lowered, for the maximum density of water is attained at 4° C, (39. 2 F.), and it expands both below and above that temperature. If you fill two strong bottles completely with ice water, cork them tightly and tie the corks securely with wire, and then let one of them be exposed to such cold that the water will freeze, and warm the other, both will burst, because the water in both bottles will expand. 367. Were it for the fact that ice is lighter than the water upon which it is formed, all those portions of the globe where the temperature in the winter season falls below the freezing point of water would be uninhabitable; for the solid water (ice) were heavier than liquid water, the ice would sink as fast as it is formed, and all the rest of the water would be gradually frozen to ice, until all the lakes and rivers were frozen solid from bottom to surface. The heat of summer would then be insufficient to melt the ice. But, as water is heavier at 4 C. than when it has any other temperature f the water at the surface of the lakes and rivers, as soon as it is cooled down to + 4 C, sinks to the bottom, and the warmer water rises to take its place and to be in turn cooled to the same temperature, until the entire body of water has a temperature of + 4 C. before any ice is formed, after which the ice formed on the.surface, being lighter than the water below, remains floating. PHYSICS. 89 At the moment of freezing, water suddenly increases in volume about ten per cent. 368. At its maximum density (+ 4 C. = 39°. 2 F.), water is 773 times as heavy (or dense) as air of o° C; but water at 15 C. is 819 times as heavy as air of the same temperature. Thus water and air expand very unequally with the increase of their temperatures. 369. Water freezes at o° C. (32 F.), or under certain con- ditions several degrees below that temperature. If you boil some water (to expel the air from it), put it in a bucket or other vessel and let it stand perfectly at rest, with a thermometer hanging down into it, allowing the water to cool slowly, the water may remain liquid until the thermometer indicates — 3 or — 4 C. But if you then suddenly stir the water around with the thermometer it will freeze at once, and its temperature will then at the same time rise to o°, because the latent heat which the water absorbed in its expansion below o° is liberated as it contracts to form ice at o°. 370. The expansion which takes place when water freezes to ice at zero (C), bursts porous stones, and great rocks may be split by boring holes in them, filling these with water, plugging the opening tightly and allowing the water to freeze. 371. Ice contracts more than any other solid upon being cooled. Under strong pressure ice may be rendered liquid even at — 18° C. 372. The melting point of ice is uniformly o° C. under the ordinary atmospheric pressure. In thus passing from the solid to the liquid state, water takes up an amount of heat sufficient to raise the temperature of a like quantity of water from o° C. to 79 C. 373. When heated above 4 C. water continues to expand until it reaches the boiling point, which is at ioo° C. (212 F.) at the ordinary atmospheric pressure. The boiling point is lower under less pressure, and higher under greater pressure. Under the pressure of two atmospheres the boiling point of water is at + 121 C, and under three atmospheres at +134° C. But on high mountains, where the barometric (or atmospheric) pressure is less (285), the boiling point of water is correspondingly lower, so that the altitudes of mountains may be determined by the temperature at which water boils on their summits. 374. Water evaporates (390) at all temperatures. Even ice gives off vapor. This tendency of water to form vapor is its tension (77) which increases as the temperature increases, and can be accurately measured. 90 PHYSICS. CHAPTER XX. RELATION OF TEMPERATURE TO THE THREE STATES OF AGGREGA- TION OF MATTER. 375. As the several states of aggregation of matter (68) depend greatly upon their temperature (314) we may look upon solids as matter in a frozen condition, liquids as melted matter, and gases as vaporized matter. Different kinds of matter con- geal or freeze to a solid mass at different temperatures ; they fuse or melt at different temperatures ; and they boil or vaporize at different temperatures, according to their kind. Hydrogen does not exist at ordinary temperatures except in the gaseous state ; indeed it requires great cold and pressure to condense it to a liquid, and that liquid boils at the low temperature of — 210 C. under a pressure equal to 190'' atmospheres, or at — 140 ° C. under 650 atmospheres. Alcohol is a liquid at ordinary temperatures, and does not freeze solid until at — 130° C; but it boils at about 78 C. (172°. 4 F.). Oil of Theobroma or "Cacao Butter" is at the ordinary temperature a solid; it melts to a liquid by the warmth of your hand, and is frozen solid again a little below that temperature. But gold is frozen solid at a temperature exceeding 1,000 degrees above zero, according to the centigrade thermometer (322), or over 1,800 degrees by Fahrenheit's scale. 376. Many solids can be changed into liquids by heat. Their liquefaction by heat is called fusion; solids which melt or fuse when heated are said to be fusible, and the particular degree of temperature (313) at which a solid undergoes fusion is called its i?ielting-point or fusing-point. Metals, resins, fats, and many other solids are fusible. But there are also many infusible solids, as starch, gums, wood, carbon, clay, etc. Ores which are either infusible, or melt only with extreme difficulty at extremely high temperatures, are called refractory ores. 377- Some solids when subjected to high heat " volatilize without fusion," or pass into a state of vapor without melting. Arsenous oxide, benzoic acid, gallic acid, calomel, and many other solid substances volatilize and sublime (405) without fusing. Vaporizable solids are said to be volatile. PHYSICS. 91 378. Softening by heat without fusion. — Many substances soften materially much below their melting point. Ointments, cerates and plasters, and the fatty substances and resins from which they are made, generally have that property. Other substances which do not fuse at all are, nevertheless, rendered soft, plastic, or pasty when heated, becoming hard again on cooling, as is the case with many dry solid extracts. 379. There are many solids which are both fusible and volatilizable; but there are other solids, which, although fusible, can not be converted into vapor. 380. Fixed substances are those which can not, by ordi- nary means, be made to* assume the gaseous state. If a sufficiently intense heat could be applied, it is probable that all sub- stances could be converted into vapor; but bodies which are not volatilized at the high temperatures which can be produced by the means at our command, are said to be fixed. Fixed alkalies are the non-volatile hydrates of potassium and sodium, but ammonia is a volatile alkali. Most mineral substances are fixed, as the metals, etc. 381. All liquids and gases can be turned into solids by cold or by pressure, or by both; but not all liquids can be converted into vapor; nor can all solids be turned into fluids. 382 Bodies in a state of fusion reassume the solid state after the application of heat has been discontinued and the usual equalization of temperature has taken place (343)' Certain substances, which solidify at high temperatures, liberate so much heat at the moment of solidification (or congelation) that they become glow.ng throughout their mass. The temperature at which liquids solidify is called their congealing point ox freezing point. Theoretically, this point is nearly identical with, or but slightly below the degree at which the solid became liquid; but it frequently happens that liquids retain their liquid state below that point, in which case they give off their latent heat all at once, when solidification at last takes place (369). 383. Expansion at the Moment of Solidification. — That water expands with great force at the point of freezing we have already noted (369). Water pipes burst in cold weather if the water in them is allowed to freeze. But some metals, too, expand when they solidify, as cast iron, tin, zinc, bismuth, anti- mony and some of their alloys. Such metals and alloys are used to make casts because they fill the molds so perfectly by their expansion that the casts become very sharp and perfect. 9 2 PHYSICS. Most substances, however, contract in the act of solidifying; thus coins of silver, gold and copper can not be cast in molds, but must be stamped. 384. A curious phenomenon connected with this subject is the fact that mixtures of solids produced by fusion, such as alloys of metals and fatty mix- tures, frequently have lower fusing points than either of the constituents of the mixture. Thus Rose's alloy, which consists of 4 parts of bismuth, I of lead, and I of tin, fuses at 94 C. (201 F.). A mixture of equal parts of potassium carbonate and sodium carbonate melts at a lower temperature than either salt separately. 385. That solids absorb heat (and render it latent) in passing into the liquid state is well illustrated in the solution of solids which take up so large an amount of heat as to greatly lower the temperature of the solvent. Whenever a solid is dissolved in any liquid, the solid must take up latent heat in passing into the liquid state, but some solids take up more heat than others. You may easily learn this by dissolving readily soluble salts in just enough water to accomplish their solution, and best by dissolving more than one salt in the same water; provided, of course, the salts used are such as do not decompose each other. Thus if you dissolve equal parts of ammonium chloride and potassium nitrate in barely sufficient water, you will observe that the temperature of the liquid falls rapidly, and the vessel as well as the solution becomes very cold. That is because the salts could not dissolve or become liquid without taking up heat, and they took this heat from the sur- rounding bodies — from the water in which they were dissolved, and then from the vessel in which the solution was performed, and from the contiguous air, and when you grasped the vessel in your hand heat was abstracted from your hand, producing the sensation of cold. 386. Freezing viixtures are made on this principle (385). Some mixtures of readily soluble salts with twice their weight of water depress the tempera- ture about 20 degrees centigrade. A mixture of three parts crystallized cal- cium chloride with two parts of snow will cause mercury to freeze. The freezing mixture used in ice cream freezers consists of about two parts of snow and one part of common salt: this will produce a temperature of about — 20 C. ( — 4 F.). Another effective freezing mixture consists of five parts hydrochloric acid and eight parts crystallized sodium sulphate. 387. There are some substances which change from the solid to the liquid state or vice versa at common room-temperatures, as glacial acetic acid, volatile oil of anise, oil of rose, etc. They are frozen solid in a cold room, and melt into liquids again in a warm room. 388. Numerous liquids are vaporizable by heat, and if the temperature at which they vaporize is not comparatively high the liquids are said to be volatile . PHYSICS. 93 Water, alcohol, ether, benzin, gasolin, are vaporizable, and all of them, except water, are volatile liquids. 389. Substances which are liquid only under pressure vapor- ize at once upon the removal of the pressure. Ammonia, carbonic oxide, nitrous oxide, and several other gases are now compressed into a liquid state in cylinders. 390. Evaporation. — The slow conversion of bodies into vapor may take place at any temperature. Thus, we have seen (374) that water vapor will pass off even from ice. Volatile solids evaporate at ordinary temperatures, as, for instance, camphor, iodine and chloral. Water evaporates constantly. Evaporation under the ordinary conditions of temperature and pressure is sometimes called spontaneous evaporation. 391. The Rate of Evaporation increases with the tempera- ture because heat increases the tension of vapors. It also varies inversely with the pressure to which the evaporating liquid is subject, because greater pressure involves greater resistance to the vapor tension. Evaporation is far more rapid in a vacuum than in air. The rate of evaporation also depends upon the amount of vapor of the same kind already contained in the air into which the evaporation is going on. It is greatest when the air is free from vapor, and ceases when the air becomes saturated. Hence, if the air be changed frequently or continually, so that it can not become charged with too great a proportion of vapor, the evaporation will proceed more rapidly than if the air is sta- tionary, and thus becomes saturated, or nearly so. In a breeze the evaporation of water from the surface of the earth is much more rapid than when the air is still. As evaporation can take place only at the surface of a liquid, the rate of evaporation also depends directly upon the extent of surface exposed. 392. The temperature beyond which a liquid can not con- tinue in a liquid condition without increased pressure is its boiling point. In other words, the boiling point of a liquid is the temperature at which it boils or becomes rapidly converted into vapor. A comparatively rapid 94 PHYSICS. conversion of a solid or liquid into vapor at the boiling point is called vapori- zation. Boiling is often called ebullition. 393- The boiling point of a liquid depends upon the nature of the liquid and upon the pressure of the superimposed air. Carbon dioxide boils at — 42°.44 C. ( — io8°.4 F.); stronger ether at yf C. (98°. 6 F.); alcohol at 78 C. (i72°.4 F.); water at ioo° C. (212 F.); mercury at 350° C. (662° F.); zinc at 1040° C. (1904 F.). Salts and other substances held in solution in the liquids generally raise the boiling points of the latter. Liquids of great density usually have higher boiling points than lighter liquids, but there are many notable exceptions. If you compare the densities and boiling points of alcohol and ether, you will find that the rule holds good; but if you compare alcohol and chloroform, you will observe that although chloroform is more than one and three-fourths times as heavy as alcohol, it boils at about 61 3 C, while alcohol does not boil until 78° C. 394. Saturated solutions of salts are often used to fix the degree of temperature applied to vessels and their contents in laboratory operations, for saturated solutions have fixed boiling points. Thus a saturated solution of common salt boils at io8°.4 C. (227 F.); one of potassium nitrate at 115°. 9 C. (240° F.); of calcium chloride at 179°. 5 C (354° F.). But the water vapor formed when these solutions boil does not retain the high temperature of their boiling points. 395. Boiling points vary with the pressure . — The vapor in its formation and continued existence must overcome all pressure from without which tends to condense it. As already stated the boiling point of a liquid is that temperature at which the tension of its vapor is greater than the pressure which it sus- tains. The measure of the atmospheric pressure must, therefore, be considered in the determination and expression of boiling points. When we speak of fixed boiling points, then, the boiling points under a pressure of one atmos- phere (284) are the boiling points referred to. At the level of the sea, water boils at ioo° C. (212° F.); on Mount Blanc it boils at 84 C. (i83°.2 F.); and in a " Papin's digester/' which is a strong, hermetically closed metallic vessel, the temperature of water may be raised to a very high degree without causing it to boil. In a steam boiler the water may attain a temperature of over 200 C. PHYSICS. q„ 396. The vapor formed from water boiling under normal pressure is of the same temperature as the boiling water, or ioo° C. (2 12 F.). Under pressure, as when the steam is con- fined in boilers, pipes, coils, steam jackets, etc., the temperature of the steam increases with the pressure. But steam may be heated after it has been produced; it may- be passed through pipes into a furnace and there heated to a very high temperature. It is then called superheated steam, or dry steam . 397. In a vacuum water boils at the ordinary temperatures. If a vessel of water of about 30 C. be placed in a glass bell and the bell then exhausted by means of an air pump, the liquid begins to boil after a few strokes; but the ebullition soon ceases on account of the pressure produced by the vapor which takes the place of the abstracted air. As soon as this vapor is pumped out, ebullition again sets in. If a long-necked flask of uniformly thin glass be half filled with water, the water boiled a few minutes so that the air might be expelled and replaced by water vapor, and the flask then removed from the source of heat, and promptly and tightly corked, the ebullition at once subsides; but if this flask be now immersed in cold water up to the neck, the contents will again boil briskly. This is because the vapor contained in the upper part of the flask is condensed by the cold so that a vacuum is produced, thus removing the pressure and greatly lowering the boiling point. 398. When a mixture of several liquids of different boiling points is heated, it boils at a temperature somewhat above the boiling point of the most volatile constituent of the mixture. 399. You have read that whenever a liquid passes into the gaseous state it takes up latent heat. This latent heat is called " the latent heat of vapors/' It requires 5^3 times as much time to convert a given amount of water into vapor as it takes to raise that water from o.°C. to ioo° C, the heat applied being . the same. Thus the latent heat of steam is 5^X100 = about 537 C. (967' F.). The same amount of heat that is necessary to evaporate one Gram of water is sufficient to raise the temperature of one Gram of water 537 degrees (centigrade), or to raise the temperature of 537 Grams of water one degree. The latent heat of alcohol vapor is about ic)0 .6C. (374°. 9 F.). That of ether vapor is about 72°.5 C. (i62°.8 F.). 400. Cold from Evaporation. — The heat which is neces- 96 PHYSICS. sary to convert a liquid into a vapor is taken from the surround- ing bodies. This fact is not noticed in vaporization by boiling because heat is con- stantly applied to the vessel containing the boiling liquid. But when evap- oration goes on at comparatively low temperatures the reduction of tempera- ture may be readily observed in the liquid itself, the vessel containing it, and the surrounding air. A rain shower cools the atmosphere because the water evaporates, and in doing so takes up heat from the air. If you put a small quantity of "stronger ether" in a watch crystal and let it evaporate at the temperature of the room, the ether will take up so much heat in its rapid evaporation that a drop of water on the other (convex) side of the watch crystal will be frozen to ice. When ether or alcohol evaporates from your hand a sensation of cold is produced. 401. When vapors are deprived of their latent heat they are immediately condensed, or return to the liquid state. Vapor can not pass into the liquid state without liberating heat. Steam heating is based upon this fact. The latent heat of steam, together with most of its sensible heat, is available for heating purposes, as it must give off that heat in returning to the common temperature. Water is often heated to the boiling point in wooden tanks and in other vessels by forcing steam into it. 402. Equal volumes of different liquids do not produce equal volumes of vapor. The expansion of water in passing into the state of vapor is greater than that of any other liquids. The value of steam as a source of mechanical power depends upon its expansive force. One cubic inch of water forms nearly one cubic foot of water vapor or steam. 403. Distillation consists in vaporizing liquids in suitable vessels, called stills, connected with condensers and receivers in such a manner that thevapor can be reconverted into the liquid state and thus collected, the object of the process being to sep- arate volatile liquids from less volatile or fixed substances. 404. Gases can be condensed into liquids, or even into the solid state, by cold, or pressure, or both. It was until 1878 supposed that air, oxygen, hydrogen and nitrogen were incompressible, incoercible, or permanent gases, i.e. , that these gases could not be condensed into either the liquid or the solid state. But all gases have now been liquefied and solidified. physics. 97 405. Sublimation is the vaporization of solids and the con- densation of the vapor back to the solid state. 406. Distillation and sublimation are applied to the puri- fication of substances resulting in the separation of volatile from non-volatile matters. CHAPTER XXI. TEMPERATURE AND HUMIDITY OF THE AIR. 407. Saturation of air with vapor. — The air is said to be -saturated with vapor when it contains as much of it as it can hold. The quantity it can hold varies with the temperature, and with the kind of vapor. The atmosphere is said to be dry when it contains a relatively small quantity of moisture, and moist or damp when it contains a greater quantity. But the sensation of dryness or humidity does not correspond with the relative per- centage of moisture, for the air feels dry whenever it is capable of absorbing much more moisture than it contains, and moist whenever it approaches the dew point, which depends greatly upon temperature. A warm air which feels dry may contain much more moisture than a cold air that feels moist. AtO° C. the air can take up -^Xs P art °f lts weight of water vapor; but for every increase of n° C. its capacity for moisture is nearly doubled, so that at about ii° C. (52 F. ) it may contain j\g of its weight (or twice as much as at the freezing point), and at 22.22 or (72 F.) it can absorb -£$ (or three times as much as at zero C). 408. The Dew Point. — If air that is saturated with moisture is cooled it can, of course, not retain all of that moisture; a portion of it must, therefore, be condensed ( ) and deposited as dew, and the temperature just below the saturation point, or that temperature at which the moisture contained in the air can not all remain in a state of vapor absorbed by the air, is call the dew point. Whenever the air is nearly saturated with moisture the dew point will therefore be only a little below the temperature of the atmosphere, and a slight fall of temperature will cause dew to be formed, for it contains more moisture than it would contain if saturated at the temperature of the dew point. The j8 PHYSICS. dew point is, therefore, lowei when the air contains less moisture, and higher when its humidity is greater. A vessel containing ice water will receive a deposit of dew upon the out- side as soon as its contents reach the dew point, which may be ascertained by a thermometer placed in the water. The relative humidity of air is its degree of approach to saturation. 4C9. Clouds, fog, dew, rain, frost, snow and hail are the results of the condensation of atmospheric moisture into liquid and solid water. When a mass of warm, moist air strikes a colder mass of air, a portion of the water vapor contained in the warmer air is condensed to clouds of little bubbles of water filled with air; when these gather and collapse, rain comes. Fogs are only clouds formed near the surface of the earth. Condensed below the freezing point, it becomes white frost. Dew is deposited upon objects which are cooled after sundown. 410. The temperature of the air is highest at the surface of the earth, and decreases as its height increases. At a certain altitude, then, the air is so cold that ice and snow never melt there. At the equator, the altitude of per- petual snow and ice is fifteen times as great as it is in a latitude of 75 , and two and one-half times as great as it is in a latitude of 75 ; but the differences depend not only upon latitude, but also somewhat upon local conditions. 411. The temperature and moisture of the air have a direct influence upon health. Thus cold and ?noist weather is accompanied with a high death- rate from rheumatism, heart diseases, diphtheria and measles; cold weather, with a high death-rate from bronchitis, pneumonia and other diseases of the respiratory organs; cold and dry weather is attended with suicide and small- pox; hot weather brings with it a high death-rate from bowel complaints; and warm, moist weather exhibits greater mortality from scarlet and typhoid fevers. CHAPTER XXII. LIGHT. 412. Light is that mode of motion which affects the optic nerve, or excites in us the sensation of vision. [Physically light is practically identical with radiant heat (314), the dif- ference being merely that of wave length.] PHYSIC 3. 99 413. The sources of light are : 1, mechanical action ; 2, chemical action; 3, electricity; 4, phosphorescence; and 5, the heavenly bodies. Bodies that emit light by their own vibrations, as the sun, or the flame of a burning substance, are called luminous bodies. But trees, rocks, and other bodies which merely diffuse light received by them from other bodies are non-luminous or illumin- ated bodies ; they do not originate light. 414. Transparent substances allow light to pass through their bodies so that objects can be seen through them. Water, air, glass, diamond ; clean, clear crystals of sodium carbonate, Rochelle salt, copper sulphate, ferrous sulphate, lead acetate, zinc sulphate, borax, alum, iron alum, etc., are transparent. 415. Translucent bodies transmit light, but so imperfectly that objects on the opposite side can not be clearly seen through them. Ground glass, horn, waxed paper, a sheet of gelatin, shellac, etc., are translucent. 416. Opaque bodies do not transmit light. By far the greater number of material objects are opaque. They cut off the light so that other objects can not be seen through them at all. 417. Luminous rays. — Light radiates in all directions from every luminous point, and a single line of light is called a ray. 418. Incandescence. — Any solid heated to nearly i,ooo° F., unless destroyed by such intense heat, emits, at that and higher temperatures, a dull red light, and is then said to be incandes- cent. The light of incandescent bodies varies with the degree of heat, being dull red, bright red, blue, orange, or white as the temperature rises; the light increasing in brilliancy with the intensity of the heat. 419. Phosphorescence is a pale light, emitted in the dark, without any heat, as the light flashing from fire-flies, the green- ish light sometimes seen in the wake of a ship at sea, or that exhibited by rotten wood, etc. 420. White Light is composed of seven colors. These seven IOO PHYSICS. colors are red, orange, yellow, green, blue, indigo and violet — the colors of the rainbow; If a beam of light admitted through a vertical slit be made to pass through a prism so placed that its edges are parallel with the sides of the slit, and the beam caught upon a screen, a band of the seven colors above named will appear on the screen. This band of the seven prismatic colors is called the solar spectrum, the white light being decomposed into its seven constit- uents in its passage through the prism. 421. Refraction. — When light passes obliquely into a medium of different density, the rays are deviated from their original direction. This tendency of the luminous rays to be refracted or bent in passing obliquely from one transparent medium into another is called refrangibility. The different color rays are not susceptible of refraction in the same degree; the red ray is the least refrangible or is less bent than the others, while the violet ray is the most refrangible. It is this unequal refrangibility that produces the spectrum or band of colors (420). 422. Simple or primary colors. — The seven prismatic colors can not be decomposed or made to undergo any change of color, and are, therefore, called the simple or primary colors. Recombined the primary colors produce white light. 423. Complementary colors are any two colors which will pro- duce white when combined. Red and green rays will produce white light and are, therefore, complementary; blue and orange, violet and yellowish-green, and indigo and orange-yellow are also complementary colors. 424. Color is produced by the light reflected by the various bodies. A body which absorbs all of the colors of the rainbow, reflecting none, appears black; one that reflects all the color rays, absorbing none, appears white; all other bodies appear to have the colors which they, respectively, reflect. A red substance seems red because it reflects only red rays of light, absorbing all the other rays. PHYSICS. 10 1 425. Fluorescence.- — Some substances have the power of chang- ing their refrangibility of rays of light. The result of this is a change of color apparent upon the surface of these bodies, a bluish, greenish, or even reddish glimmer being diffused by them. Fluor-spar, an acid solution of sulphate of quinine, tincture of turmeric, the fluid extracts of gelsemium and stramonium seed, and many other organic substances exhibit fluorescence. The glucoside aesculin contained in horse- chestnut bark has this property in a marked degree, one grain being sufficient to impart a distinct fluorescence to over twenty gallons of water. 426. Rays of light have three properties ; they are: 1, lumi- nous; 2, heating; and 3, producing chemical action. The luminous intensity is greatest in the yellow, and least in the violet rays. The intensity of heat is least in the violet and increases to (and beyond) the red. The spectrum contains invisible dark rays of heat, which are less refrangible than the red rays. Light has a marked influence upon chemism. 427. The chemical action of light is necessary to the healthy growth of plants. Many plants do not thrive at all in the shade. For the elaboration of their food plants need the light as well as the heat of the sun's rays, and those rays of light which favor chemical reaction are of vital importance. The bleaching power of light depends upon its chemical effect. That light has very great power in this direction is shown by many of the familiar changes occurring in medicinal chemicals, as the darkening of yellow oxide of mercury, white precipitate, pyrophosphate of iron, etc., on exposure to light. Photography is based upon the decomposition of silver compounds by light. Hydrogen and chlorine combine very slowly in diffused light, but with explosive violence in direct sun-light. 428. But the chemical effect of the different rays is not equal. It is hardly perceptible in the red and yellow rays, but increases gradually toward the opposite end of the solar spectrum, becomes decided in the blue, and reaches its maximum intensity in and beyond the violet. Thus the chemical effect of the rays increases with their refrangibility, and the spectrum contains rays beyond the violet which are more refrangible than the violet rays, but not visible. 429. The chemical effect of light renders it necessary to pro- tect medicinal substances from its action. Containers of colorless flint glass are, therefore, not suitable for holding substances affected by light ; blue or violet glass bottles, instead of affording 102 PHYSICS. protection, hasten the decompositions or changes produced by light, as they transmit the chemical rays freely, while red, yellow, or amber-colored glass affords good protection by excluding the chemical (or " actinic ") rays. The damaging effects of direct sun-light upon medicines are more far- reaching than is commonly supposed. CHAPTER XXIII. ELECTRICITY. 430. Electricity can not be defined since it is not known what it is. It manifests itself by peculiar and striking phe- nomena of attraction and repulsion and in various other ways. Electricity may be converted into all other forms of energy, and all other forms of energy can be converted into electricity (66). 431. Examples of the wonderful effects of electricity are seen in the lightning, the telegraph, electric lighting, the compass, magnets, electric motors, the telephone, etc. 432. There are two principal sources of electricity — friction and chemism. Electricity developed by friction is called frictional electricity, or static electricity, It is also sometimes called " Franklinism." Electricity developed by chemism is called galvanic electricity, or voltaic electricity, or dynamic electricity. 433. Magnetism is a manifestation of the electric force. The power of the lode-stone to attract iron is magnetism. Lode-stone is an iron ore called "magnetic oxide of iron," and is a natiaal magnet. Artificial magnets may be made by means of dynamic electricity. 434. While electric force developed by different means may exhibit differences as to some property, yet these differences are only differences as to degree and not as to kind. All the different forms of electricity are iden- tical, each having all the properties of any other. PHYSICS. 103 435. It has already been stated (430) that electricity exhibits striking phenomena of attraction and repulsion. This is because electricity has two opposite states, one called positive electricity and the other negative electricity. Both kinds of electricity are always simultaneously produced. If a lode-stone is rolled about in iron filings the iron will adhere to it, especially at the two opposite ends, which are called the poles of the magnet ; each pole attracts iron or any other magnetic substance ; but two magnets brought end to end will not attract each other regardless of which ends are thus brought together, for each end of the first magnet will attract but one end of the second magnet and will repel the other end. 436. An artificial magnet, or a steel needle which has been magnetized, poised at the center so that it will swing freely, is a compass. One of its ends always points toward the north and is called the north pole ; the opposite end is called the south pole. The north pole of one magnet attracts the south pole of the other, but if the north poles of two magnets are brought together repulsion takes place instead of attraction. Thus opposite poles attract while like poles repel each other. Electricity is, therefor called a polar force. 437. Induction. — A piece of soft iron, or a piece of steel, may be magnetized by being brought near one of the poles of a magnet. The soft iron will become a temporary magnet, with its two poles, capable of attracting iron ; but it will soon lose its magnetic power. A rod of steel, on the other hand, treated in the same manner, becomes a permanent magnet. This power of any magnet to develop magnetism in a piece of iron or steel is called Induction. The magnet thus used to make another magnet does not lose any of its force. 438. Magnetic substances are such as are attracted by a mag- net ; among them are iron, steel, nickel and cobalt, and in less degree magnetic are manganese, chromium, platinum, plumbago and oxygen. 439. Certain substances exhibit a remarkable property in reference to magnetism. If suspended between the poles of a powerful magnet in the shape of a horseshoe, they assume a position at right angles to the line join- ing the poles, as if they were repelled by both poles. Phosphorus, bismuth, 104 PHYSICS. antimony, zinc, tin, resin, and hydrogen act in this manner. Such substances are called diamagnetic. 440. Effects similar to those produced by a magnet may be produced by very simple means. A stick of sealing wax rubbed with dry flannel has the property of attract- ing to itself small pieces of paper, shreds of cotton and silk, feathers, gold leaf, sawdust, and other light bodies. The stick of sealing wax having been negatively electrified by the friction produced by the flannel attracts light bodies. But the bodies attracted to the sealing wax become in turn charged with the same negative electricity and are then no longer attracted but repelled, so that they do not fall off the wax but are really throivnoft.. A warm glass rod rubbed with a silk handkerchief, or a silk pad, also attracts and afterwards repels light bodies; but the glass is Positively elec- trified. The polarities of the wax and the glass rod are opposite, and hence the bodies repelled by the one are attracted by the other. Two bodies charged with like electricities repel each other; but two bodies of opposite electrical polarities attract each other. 441. Other phenomena of electricity which may be readily produced are these: A hard rubber comb attracts the hairs to itself in the act of being used. If you put a piece of zinc upon the tongue and a silver coin under it no peculiar sensation is perceived if the metals are not in contact; but if you let the metals touch each other at the edge while placing your tongue between them, a singular, disagreeable, tingling sensation and taste is developed. If you place a silver coin between the upper lip and the teeth instead of under the tongue, and the piece of zinc above the tongue, and then bring the two metals into contact with each other, the peculiar taste will be perceived as before, and, besides, there will be, each time, a momentary flash of light appearing to pass before the eye. Light is emitted when a cat's fur is stroked in the dark. All these are electrical phenomena. 442. Conductors of electricity are substances which readily transmit electricity from one body to another. Substances that do not transmit electricity are called non- conductors, or insulators. But these distinctions are only relative, for there are no perfect conduct- ors, nor any perfect insulators. 443. Active chemism, or a chemical reaction (522), is always attended by the development of electricity. The electricity PHYSICS. 105 thus developed js dynamical electricity; while identical with stat- ical orfrictional electricity, its discharge is continuous while the current of statical electricity is only momentary. 444. Electric currents are commonly produced by chem- ical action between metals and corrosive liquids. The voltaic current is thus produced when one strip of copper and another of zinc are placed in dilute sulphuric acid in a glass jar, the'two strips of metal being connected, above the acid, by a wire, which serves as the conductor. This apparatus is called a voltaic, or galvanic, element or cell. 445. A number of voltaic cells connected so that the cur- rent has the same direction (446) in all, constitute a voltaic bat- tery. 446. Direction of the Currejit. — The positive current of elec- tricity within the liquid is from the zinc to the copper (447), and above the liquid from the copper to the zinc, thus producing a circuit. To connect the plates by means of the metallic wires (copper wire is used), is called closing the circuit, and to separate them is to break the circuit. 447. The current starts from the zinc because that is the metal most easily acted upon by the acid, and that metal is, therefore, called the generat- ing plate, while the copper is the conducting plate. The generating plate is also called the positive plate and the conducting plate the negative plate. 448. Many different kinds of cells and batteries have been invented and several are in use, all based upon the fact that chemical reactions produce electricity. 449. Poles. — If the wires be disconnected, or the current broken, the positive electricity will tend to accumulate at the end of the wire attached to the negative plate (the copper), and the negative electricity on the wire attached to the positive plate (the zinc). The ends of the wires are called the poles, or electrodes, of the circuit. The wire attached to the negative plate is the positive pole, and that attached to the positive plate is the negative pole. 450. Chemical effects of the electric current. If a chemical compound be placed between the poles or electrodes of a bat- 106 PHYSICS. tery and thus made to form a part of the external voltaic cir- cuit, chemical decomposition will take place. This process of decomposition is called electrolysis, and any substance capable of electrolytic decomposition is called an electrolyte. Electrolysis proves a remarkably intimate analogy between electricity and chemism which will be referred to again. 451. Electroplating and electrotyping are performed on the principle of electrolysis, the metal being separated from its salt and deposited on the nega- tive electrode, which may consist of the article to be plated provided it pos- sesses a conducting surface. PART II CHEMISTRY. PART II CHEMISTRY CHAPTER XXIV.— Introductory. MASSES, MOLECULES AND ATOMS. 452. The three great divisions of the material world are the Animal Kingdom, the Vegetable Kingdom, and the Mineral Kingdom. All natural material objects around us belong to one or another of these three kingdoms. The artificial material things, which are the result of man's labor, may be made up of matter derived from two or all three kingdoms of Nature. 453. Inorganic or Mineral Substances are those belong- ing to or derived from the mineral kingdom. They include stones, earth, metals, and all chemical compounds, except the compounds of carbon and hydrogen and their derivatives. The metallic salts, as the compounds of potassium, sodium, calcium, zinc, iron, mercury, lead, etc., and the " mineral acids," as sulphuric, phosphoric, nitric, hydrochloric and hydrobromic acids, are thus all inorganic compounds. 454. Organic Substances are those belonging to or derived from the animal and vegetable kingdoms, and the numerous derivatives of the hydrocarbons and many other carbon compounds. All our plant drugs and animal drugs, together with the substances extracted from them, as alkaloids, gums, resins, etc., and all our fluid and solid extracts are among ihe organic substances. Acetic, oxalic, citric, and tartaric acids, tannin, santonin, sulphate of quinine, sugar, starch, alcohol, glycerin, ether, chloroform — all are organic substances. 109 110 CHEMISTRY. 455. By far the greater number of bodies in nature are made up of various substances in various proportions. They consist of unlike masses and unlike molecules mixed together. This is true of both organic and inorganic bodies. It is strik- ingly evident that all animal bodies consist of many different substances, some solid and some liquid, some hard and others soft, some of one color and others of another color, etc. Plant tissues, as wood, etc., also consist of many different things. These are, therefore, heterogeiieous masses, or mixed substances. 456. But there are also many bodies which appear, even upon close examination, to have a perfectly homogeneous mass throughout. Water is thus uniform. It appears to be of per- fect sameness in every minutest particle of its mass; and, in reality, it is but one substance or kind of matter. A large num- ber of minerals, ores and metals also appear to be, and really consist of but one kind of matter throughout their mass. Other bodies, again, which have the appearance of perfect sameness in their every least particle, nevertheless consist of more than one kind of matter, as is the case with air, solutions and mixtures of certain liquids. 457. If a piece of sugar be put in a tumblerful of water, the sugar dis- solves and the sugar and water form a solution, in which they are so inti- mately blended that every drop of the liquid is precisely like every other drop, and it is impossible to distinguish the particles of water from the particles of sugar in that liquid. Yet, we can separate the water from the sugar, for the water is vaporizable, while the sugar is fixed; and, hence, the water can all be evaporated, leaving as a residue the whole amount of sugar which we put into the water. Therefore, the water and sugar must have been blended or intermingled with each other without losing their respective identities, every particle of either of them remaining wholly distinct from every particle of the other, although we could not see this to be the case, the particles being too minute to be perceptible, even with the aid of the most powerful microscope. 458. If you mix together, by trituration, in a mortar, one scruple of calomel and one scruple of sugar, the result will be a mixture so perfect that it looks as if it were but one substance. But if you mix this powder with an ounce of water in a dish; pour off the water which washes out the sugar by dissolving it; repeat the washing with fresh portions of water until the water no longer acquires any sweetish taste, and then let the residue dry, and weigh CHEMISTRY. in it, you will find that residue to be the one scruple of calomel. The sugar and the calomel were neither of them lost or altered by being triturated together, but were only mixed, and their separation was easily accomplished by simple physical means. 459. If you mix an ounce of alcohol and an ounce of glycerin, the mix- ture looks quite as uniform as water; but if you heat the mixture in a dish over a water-bath a sufficient time, all the alcohol will be driven off, and the glycerin will all remain in the dish. 460. Mix 20 grains of each of magnesia, sugar, rosin and charcoal, and reduce all to a uniform fine powder. It looks as if it were but one substance. Now mix it with enough water to make a thick fluid; transfer this to a paper filter in a small glass funnel; rinse the mortar and pestle with a little more water so as to get all of the powder added to the rest on the filter. Collect the liquid which runs through the filter; evaporate it to dryness and weigh the residue. Let the filter and contents dry. Then add to the powder in the filter just enough alcohol to moisten both the filter paper and contents, and, after a few minutes, add enough alcohol to cover the whole of the black mass in the filter, and collect all of the liquid that passes through, and evaporate it to dryness and weigh the residue. Allow the filter and contents to become nearly dry again, and then treat the remainder of the mixture in the filter with a mixture of sixty minims of diluted sulphuric acid and one-half fluid ounce of water in the same manner as you before treated the contents of the filter with alcohol; collect the liquid that passes through and evaporate it to dryness. Then wash the residue on the filter with two fluid ounces of water by pouring that water into the filter on the contents and letting it run through. Collect this filtrate also and evaporate a portion of it to dryness. Now, examine your several residues. You will find, if you have done your work well, and used enough of the water in the first, and of the alcohol in the second washing, that the first residue is your sugar, and the second residue is your rosin. The third residue, however, is neither sugar, rosin, magnesia nor charcoal, but a bitter white substance, soluble in water, quite unlike magnesia; it is, in fact, Epsom salt, and weighs over seventy grains. The last wash water will leave no residue, and if you now put the filter and contents in a dish over the water-bath and dry them perfectly, you will find that when they are put on the pan of the balance their total weight is about twenty grains, in addition to the weight of a paper filter of the same size as used in your experiment; that will account for your charcoal, which all remains in the filter to the last. If you taste the sugar, burn the rosin, and also sub- ject the charcoal to such simple physical tests as you can think of, you will conclude that they are these substances and no other. , In this experiment it is shown that the original mixture of the four powders contained at least the sugar, rosin and charcoal unchanged. Indeed, 112 CHEMISTRY. the magnesia, too, was unchanged in that mixture, but the sulphuric acid turned it into Epsom salt, which is water soluble, and it was thus separated from the charcoal. This change of the magnesia to Epsom salt was a chemical change. 461. But sometimes it is very difficult to determine by physical means whether or not a body is a mixture of different substances, or but one single substance. 462. All kinds of matter consist of one or more kinds of ato??is united into molecules. 463. Atoms, as already stated (20), are the smallest par- ticles into which any kind of matter can be sub-divided. Thus they are the absolutely indivisible particles of matter, of which all molecules and masses are made up. The} r are the smallest particles of matter which can take part in chemical reactions (522) or combinations. As atoms are indivisible, they are, therefore, of course, also undecomposable. An atom can pass simply from one molecule to another, or a group of atoms liberated from one molecule may be re-arranged into other molecules; but it is held that no other atom can continue to exist singly, independently, or alone, or in a free state, or uncombined with some other atom or atoms. 464. Kinds of Atoms. — Only seventy different kinds of atoms, or seventy kinds of undecomposable matter, are so far known to exist. It seems probable that some other kinds of atoms not now known are in existence and may yet be discovered. On the other hand, it may be that all our so-called elements may be found to be but different conditions of but one or two kinds of primary matter. 465. The seventy different kinds of atoms now recognized as existing are enumerated in the following TABLE OF ELEMENTS AND THEIR SYMBOLS. Aluminum Al Caesium Cs Antimony (Antimonium Calcium Ca or Stibium) Sb Carbon (Carboneum) C Arsenic (Arsenicum) As Cerium Ce Barium Ba Chlorine (Chlorum) CI Beryllium (See Glucinum) Be Chromium Cr Bismuth (Bismuthum) Bi Cobalt (Cobaltum) Co Boron B Columbium Cb Bromine (Bromium) Br Copper (Cuprum) Cu Cadmium Cd Didymium Di CHEMISTRY. 113 Erbium Er Potassium (Kalium) K Fluorine (Fluorurrn F Rhodium Rh Gallium Ga Rubidium Rb Germanium Ge Ruthenium Ru Glucinum Gl Samarium Sm Gold (Aurum) Au Scandium Sc Hydrygen (Hydrogenium) H Selenium Se Indium In Silicon (Silicium) Si Iodine (Iodum) I Silver (Argentum) Ag Iridium Ir Sodium (Natrium) Na Iron (Ferrum) Fe Strontium Sr Lanthanum La Sulphur S Lead (Plumbum) Pb Tantalum Ta Lithium Li Tellurium Te Magnesium Mg Terbium Tb Manganese (Manganum) Mn Thallium Tl Mercury (Hydrargyrum) Hg Thorium Th Molybdenum Mo Tin (Stannum) Sn Nickel (Niccolum) Ni Titanium Ti Niobium (see Columbium) Nb Tungsten (Wolframium) W Nitrogen (Nitrogeniumj N Uranium U Osmium Os Vanadium V Oxygen (Oxygenium) O Ytterbium Yb Palladium Pd Yttrium Yt Phosphorus P Zinc (Zincum) Zn Platinum Pt Zirconium Zr The name Beryllium is now obsolete, the name Glucinum having taken its place. The name of Niobium has been changed to Columbium. Finally Didymium has been recently split up into two kinds of atoms called Neo- didymium and Praseo-didymium. Thus the different kinds of atoms in the preceding table are seventy in number. 466. Endless as is the variety of substances, all material bodies in Nature, so far as at present known, are aggregations of molecules (470), each made up of one or more of this limited number of atoms (465). 467. Atoms are endowed with chemical energy caused by a force called chemism, or chemical force. Chemism is also called combining power, chemical attraction, chemical affinity and atomic attractio?i. Atoms are united with each other by this force into mole- cules, and can not be separated from these molecules unless under such conditions that they may immediately form new molecules. 468. All atoms of the same kind have the same size and the same weight. But atoms of different kinds have different 114 CHEMISTRY. weights. The absolute weight of any atom is unknown; but its relative weight, being constant, can be determined in several different ways with great accuracy. 469. Whenever any two or more atoms unite with each other by virtue of the chemical attraction between them, and their chemical affinities are thus satisfied or neutralized, a mole- cule (470) is the result. When the atoms thus unite, their chemical affinities are spent or satisfied. Molecules, therefore, have no chemical energy or affinity, and can consequently continue in independent exist- ence. 470. Molecules, as already stated elsewhere (16), are the smallest particles of any kind of matter that are capable of continued existence as such. They are the smallest particles into which any kind of matter can be divided without losing its identity, or without being thereby converted into some other kind or kinds of matter; for when molecules are divided into their constituent atoms they cease to exist, and the atoms form new molecules. 471. Masses are made up of molecules. Molecules are either elemental or compound. Elemental molecules consist of atoms of but one kind. Compound molecules are composed of more than one kind of atoms. 472. Elements are substances consisting of elemental molecules (471). In an element, therefore, the mass, the molecule and the atom each consist of one and the same kind of matter. The elements, therefore, can not be decomposed into other kinds of matter. • There are accordingly as many elements as there are differ- ent kinds of atoms. Thus, seventy elements are at present rec- ognized (465). Upon examination of the table of elements (465) you will find in it all of the known metals. In fact, about four-fifths of the elements are metals. CHEMISTRY. 115 Of the whole seventy only five elements are gases at the com- mon temperatures, two are liquids, and all the others solids. 473. Chemical compounds are substances consisting of but one kind of compound molecules (471). Any substance containing more than one kind of molecules is not a definite chemical compound but is a mixed substance (482). We have learnt that there are but seventy different kinds of matter called elements; all other distinct kinds of matter are chemi- cal compounds, or compound matter. 474. Chemically homogeneous bodies are such as consist of but one kind of molecules, whether elemental or compound. All elements and all chemical compounds are therefore chemi- cally homogeneous. 475. As all masses of matter are made up of molecules, and the molecules are the smallest particles into which matter can be divided without being changed into some other kind or kinds of matter (470), the mass is divisible into molecules without change of kind, but the molecule can not be split up into its constituent atoms without ceasing to be the same kind of matter (15 and 17). 476. Number of kinds of matter. — There are as many dis- tinct kinds of matter as there are different kinds of molecules and vice versa. They are countless. 477. Each molecule of any one chemical compound invaria- bly contains the same total number of atoms, the same kinds of atoms, and the same number of each kind of atoms, and all its atoms are always in precisely the same positions relative to each other. 478. No two bodies or masses can both consist of one and the same kind of molecules without being the same kind of matter. 479. All molecules of the same kind have also the same size and the same weight; and all molecules whatsoever, whether of the same kind or not, have the same volume when in a state of vapor. Il6 CHEMISTRY. 480. Each chemical compound, because it has precisely the same chemical composition and structure (477) under all cir- cumstances, has also precisely the same chemical properties; and, moreover, each distinct kind of matter has uniformly the same physical properties under the same conditions. 481. Any two or more bodies having the same chemical and physical properties must consist of the same kind of matter. 482. Mixed Substances, or heterogeneous masses, are bodies consisting of more than one kind of molecules. A mixture, or mixed substance, is made up of as many different substances as there are different kinds of molecules in it. 483. Recapitulation. — Every body or mass of matter of whatever kind is an aggregation of molecules. These mole- cules are held together by cohesion if of the same kind, but by adhesion if of different kinds. Each molecule is the smallest individual particle of any kind of matter having the properties of the whole mass, and, therefore, the smallest particle of any kind of matter that is capable of subsisting. In any one distinct kind of matter every molecule is like every other molecule and like the whole mass. There are as many different kinds of matter as there are different kinds of molecules, and no more. Every molecule of any one particular kind has exactly the same weight and the same volume as every other molecule of the same kind ; and all molecules of the same kind, moreover, contain each the same number of atoms, the same kinds of atoms, the same number of each kind of atoms, and the same internal atomic structure or grouping of the atoms. All molecules of whatever kind, when in a state of vapor, have the same volume. As the kind of matter is determined by the composition and structure of its molecule, any change in the composition or structure of its molecule involves the change of that kind of matter into a new or different kind or kinds of matter. All molecules are made up of atoms united by chemism. CHEMISTRY. II- There are seventy different kinds of atoms. Atoms are absolutely indivisible particles of matter. All atoms of the same kind have the same weight and the same volume.. The different kinds of molecules or different kinds of matter are countless; yet they all consist of one or more of the seventy different kinds of atoms, so far as at present known. When atoms of but one kind form molecules, the resulting molecules are simple kinds of matter, or elements; there are, con- sequently, as many different elements as there are different kinds of atoms, and no more. But when unlike atoms, or atoms of different kinds, unite, the molecules thus formed are compound matter. A chemically homogeneous mass is a mass composed of but one kind of molecules. Such a body is called a definite chem- ical substance. If all the molecules of such a mass consist of but one kind of atoms, the mass is that of an element; if they consist of more than one kind of atoms, the mass is that of a definite chemical compound. But the greatest number of material objects or bodies in nature have masses composed of different kinds of molecules, and are not chemical compounds but only mixtures, each ingredient of which is distinct from every other ingredient in it. 484. Physical Properties. — The physical properties of matter are those which belong to their masses and molecules. They include among others the form, state of aggregation, consistence, specific weight, vapor density, specific volume, color, odor, taste, solubility, melting point, congealing point, boiling point, etc. 485. Physics is that part of physical science (486) which concerns the states and changes of matter without (outside of) the molecules, and thus the physical properties (484)- But Tl8 CHEMISTRY. physical changes can not involve the essential physical proper- ties of matter because they do not affect its identity or kind. Physics is the scientific study and knowledge of molar and molecu- lar matter. 486. Physical Science is the systematic pursuit and classi- fication of all knowledge of matter and of the forces by which matter is affected. It takes cognizance of the bodies of matter, the conditions, motions and changes to which these bodies are subject, and the laws governing the phenomena of physics and chemistry. 487. The Chemical Properties of matter are those proper- ties which depend upon its atoms alone. They include the rel- ative weights, valence (607), chemical energy (514) and electro- chemical polarity (564) of the atoms; and the relative weights, structure, and analytical and synthetical reactions (522) of the molecules. 488. Chemistry is that part of physical science which treats of the structure ancl changes of matter within the mole- cule. It is the science of the constitution and relative stability of molecules. // is the scientific study and knowledge of atomic matter. CHAPTER XXV. CHEMICAL PHENOMENA. 489. Chemical Phenomena. — We have learnt (27) that matter is indestructible, or that it can not be annihilated. By the agency of chemism one kind of matter can be transformed into some other kind or kinds of matter; but it can not be changed as to its amount. The amount of matter in the universe can CHEMISTRY. II 9 neither be added to nor diminished, for it is uncreatable as well as indestructible. 490. Any substance may undergo change, and this change may be so great as to involve loss of identity; but in every such case the matter of which that substance was composed has not been destroyed but has simply been transformed into some other substance or substances. When alcohol burns it disappears from sight, and as alcohol it no longer exists. But the matter of which the alcohol was constituted has not been destroyed. The elements of which alcohol is composed are carbon, hydrogen and oxygen ; these three elements are capable of forming numerous compounds with each other and alcohol is one of these compounds. When alcohol is ignited it is decomposed by the combustion, and its carbon, hydrogen and oxygen, together with a certain amount of oxygen from the air, pass into other combinations — carbon dioxide and water — which are invisible in the gaseous state assumed by them when formed by the combustion of the alco- hol in the air. 491. Whenever any substance is, as we say in common par- lance, totally destroyed by fire, that substance may so completely lose its identity or its properties that it can no longer be recog- nized, and indeed is no longer the same substance; but instead of being lost or annihilated it has been transformed into other kinds of matter, and if the apparent destruction of the substance be accomplished under such conditions that the new products formed out of the substance so destroyed can be collected and weighed it is found that every particle of the original substance can be accounted for as entering into these new products. 492. Any two or more chemically homogeneous bodies (474) exhibiting, respectively, different properties can not sev- erally consist of the same kind of molecules. 493. Whenever any body acquires permanently different properties by being subjected to the action of heat, light, air, moisture, or an electric current, or by contact with another body, or from any cause whatsoever, it has ceased to be the same kind of matter as before. It has been converted into some other kind of matter, or undergone a chemical change ; or chemical reac- tion, or chemical decomposition, and these changes, reactions, or decompositions are chemical phenomena. 120 CHEMISTRY. 494. No two or more different kinds of matter have pre- cisely the same physical properties in all respects. Whenever any kind of matter is changed as to its kind it is also changed as to its physical properties. Mere mixtures or heterogeneous masses may, however, be changed as to their properties without loss of identity of the several ingredients ; any admixture changes the character of the whole. 495. Among the physical properties of matter are form, color, odor, and taste. Any one kind of matter always has the same physical properties under the same (or unchanged) conditions. Lead iodide is always yellow. A yellow color does not prove that the substance having that color is lead iodide ; but the absence of the yellow color does prove that the substance is not lead iodide. Ammonia has a peculiar, strong odor. Any substance which does not possess that odor can not be ammonia. An acid liquid can not be sugar, for sugar is a solid and has a sweet taste. Salicin can not be mistaken for potassium iodide, for salicin consists of bitter, silky, slender crystals, while potassium iodide has a pungent, saline taste and crystallizes in cubes. A water soluble solid can not be calomel, nor can a crystalline precipitate be castor oil. 496. A change produced in the physical properties of bodies accompanies any chemical change which they may be made to undergo. Indeed striking changes in the color, odor, or other physical properties of a body generally denote that it has been con- verted, in whole or in part, into some other kind of matter. 497. Many chemical changes proceed quietly and unac- companied by any marked physical signs, but many other chem- ical changes are attended with striking physical phenomena, such as fire, explosion, etc. Fire is always the result of chemical reaction. Explosions of gun powder, dynamite, gun cotton and gas, are caused by chemical reactions. Other less noisy and less dangerous evidences of chemical change are exhibited in the following experiments. CHEMISTRY. 12 1 498. Put two or three little crystals of chromic acid on a piece of paper; put about fifteen drops of alcohol in a graduate or bottle, then pour that alco- hol over the crystals, and observe the commotion that instantly follows. The heat liberated by the reaction ignites the alcohol; hence, it is safer not to add the alcohol out of the shop bottle, but to put the small amount required in another vessel before adding it to the chromic acid. 499. Put a little diluted sulphuric acid in a graduate and add to it a little potassium carbonate; a lively effervescence takes place and the mixture becomes warm. 500. Place about half a teaspoonful of each of potassium carbonate and ammonium chloride in a mortar. Observe before they are mixed that neither of them has any odor. Then rub them together and note that the odor of am- monia is developed. 501. Mix four grains of corrosive sublimate in a mortar with five grains of potassium iodide; the materials are both white, but the mixture will be scarlet red. 502. Touch a little diluted sulphuric acid with the end of your tongue and observe how acid it tastes; taste also a little magnesia, and notice that it has only a faint, earthy taste. Then put two fluid-drachms of the diluted sul- phuric acid in a graduate and add one drachm of magnesia; stir well, and when the liquid no longer dissolves any more of the white powder taste the liquid. You will find that it is neither acid, nor of a faint, earthy taste; it is, instead, of a cooling, saline, bitter taste. 503. Dissolve a grain of blue vitriol, or copper sulphate, in two ounces of water; observe that the color is very pale bluish; add a few drops of ammonia water and see how the color changes to a beautiful deep blue, which does not belong to either water, copper sulphate, or ammonia, but to a new substance formed in the liquid. 504. Dissolve one-half grain of sodium salicylate in a half-pint of water; add a few drops of tincture of chloride of iron and observe the reddish or pur- plish color produced in the mixture; now add about a fluid-ounce diluted hydrochloric acid and the color disappears again. 505. Dissolve thirty grains of pure sulphate of iron (or of clear, green crystals of copperas) in half an ounce of water, and dissolve fifteen grains of oxalic acid in another half ounce of water; mix the two solutions and observe that a yellowish color first makes its appearance and afterwards a yellow pow- der is found in the liquid. 506. Mix one fluid-drachm of tincture of chloride of iron with two fluid- drachms of ammonia water and observe that a copious brown-red precipitate is formed. 507. Mix one fluid-drachm of tincture of chloride of iron with two fluid- drachms of simple syrup, and then add two fluid-drachms of ammonia water; 122 CHEMISTRY. observe that no precipitate is formed, but a deep brown red color is produced. Compare this experiment with that described in the preceding paragraph. 508. Put a fluid-drachm of syrup of iodide of iron in a graduate and add a little solution of potassa; observe the deep green color brought out. 509. Put one fluid-drachm of tincture of iodine in a one-ounce bottle; add about fifteen minims stronger water of ammonia and one drop of carbolic acid; shake; observe that the dark iodine color soon disappears, leaving a colorless liquid. 510. The experiments described in paragraphs 498 to 509, inclusive, are all examples of chemical reactions accompanied by evident physical signs, such as fulmination, effervescence, the development of odor, changes of color, change of taste, the discharge of color and the formation of insoluble substances in liquids. The results of these experiments are sufficiently striking to excite inter- est in the causes and effects. And yet how feeble they are beside the won- derfully active chemical reaction which we call fire, or the explosion of the charge in a gun! 511. There are numerous examples of slow chemical changes or reac- tions all around us which we may witness if we are observing. A bright iron nag] exposed to air and moisture will rapidly become rusty; the rust is an iron compound formed by chemical reaction, and to recover the iron again from that rust requires a chemical process. Bright copper or brass turns green when acted upon by air and grease, or by vinegar; the green compound is a product of chemical action. When limestone is heated in a kiln, it is decomposed and quick lime remains; if the quick lime is mixed with water it becomes slaked, heat is gen- erated by the chemical action, and the white liquid which results does not contain quick lime by calcium hydrate. Both changes are chemical. When copperas is exposed to the air it becomes brown on the surface ; the brown substance is not copperas but another compound formed by chemical action. Nitrate of silver and yellow oxide of mercury darken on exposure to light as a result of chemical decomposition. Fermentation, by which malt, syrup and sugar yield alcohol, and by which weak alcoholic liquids, like cider and weak wines, turn into vinegar, is a chemical process. The change by which the rich green of the foliage of our forests is changed to the beautifully varied hues of autumn leaves, is also the result of chemical reactions. The decay of wood and other organic substances, the putrefaction of animal matter, the digestion of food — all these are chemical processes, involv- ing chemical changes; produced by chemism, and resulting in the decomposi- tion of the old molecules and the formation of new ones in their places. CHEMISTRY. I 23 512. Relative Stability of Molecules.— Some substances resist chemical influences and changes to a remarkable degree. The molecules of platinum, gold, quartz, clay, carbon, and many other substances remain unaltered under ordinary conditions. On the other hand, there are also numerous substances which are easily affected by air, moisture, changes of temperature, the influence of light, or by contact with other substances. 513. Chemical Changes or Reactions or phenomena are those changes in matter which extend not only to its physical properties, but which involve the very identity of its kind. So long as the molecule is unchanged, the matter of which it consists remains of the same kind, but when the molecule is divided or decomposed, or its interior structure altered, that change is a chemical change or reaction, because it changes both the physical properties and the kind of the matter. CHAPTER XXVI. CHEMISM. ITS INTENSITY, QUALITY, AND QUANTITY. 514. Chemism is the force which manifests itself by atomic attraction and repulsion, and by which molecules are formed, altered or decomposed. It is the force by which matter is altered as to its kind. The transformation of any kind of matter into any other kind or kinds of matter is effected by chemism, and never directly by any other cause (515). 515. Matter may be altered as to its kind, or its alteration may be prevented, apparently by other agencies than chemism, but only in an indirect way. Heat, light and electricity cause chemical changes to take place; but only by aiding chemism, or by producing conditions favorable to the action of chemism. 124 CHEMISTRY. Chcmism may be aided or opposed by other forces, and may be converted into other forms of energy, or other forms of energy may be converted into chemism. But that energy which changes matter as to its kind is always and alone chemism. 516. All atoms are endowed with or subject to chemism. It is because of this irresistible force that atoms can not subsist singly or uncombined, but are compelled to seek new partners as soon as they are liberated from their previous partnership in some other molecule, and can thus only pass from one molecule to another. 517. In thus causing and directing the separation, union, or rearrangement of the atoms, the chemism of these atoms is neutralized, or saturated, or rendered latent. All molecules are, therefore, neutral. Chemism operates only between atoms; never between mole- cules. 51S. But changes of matter from one kind to another kind would be impossible were it not for the separation of atoms from each other and their re-arrangement into new molecules. It therefore follows that atoms must be made free before they can be again tied to or combined with other atoms. At the moment of their transfer from one molecule to another they are free and endowed with active, unsatisfied combining power or chemism. 519. Radicals. Atoms and groups of atoms whose chemism is wholly or partly unsatisfied are called radicals. A simple or elemental radical is a single atom in a free state, or with all its chemical combining power in full play. All atoms in a free state are simple radicals. A coj?ipoufid radical is a group of two or more atoms of differ- ent kinds, tied together by a part of their chemism, but having another part of their chemism still unsatisfied. The atoms in such a group act together as one radical, or as if the whole group were but one atom. Radicals, then, are atoms or groups of atoms liberated from molecules, and impelled by chemism to unite with other radicals to form new molecules. CHEMISTRY. 1 25 520. Radicals differ as to the intenity, quality and quantity of their chemism. By inte?isity of chemical energy is meant the relative power of the affinity of one radical as compared with that of another (521). The quality of the chemism of any radical is indicated by the character and conduct of the compounds it forms, and depends upon its electro-chemical polarity (564). The relative quantity of the chemism of a radical is expressed by the term valence (607). 521. The relative energy or intensity of chemism is in many instances very marked. Radicals unite according to their mutual attractions or affinities. The attraction between some radicals is relatively stronger or weaker than the attraction between other radicals. Thus the chemical affinity between potassium atoms is weaker than the affinity of potassium atoms for the atoms of oxygen, and phosphorus atoms have a greater affinity for hydrogen atoms than they have for nitrogen atoms. Hydrogen conducts itself as a neutral or chemically indifferent substance under ordinary conditions. Chlorine, however, attacks other substances with great energy. Sulphuric acid is far more energetic in its chemical action than boric acid; the sulphuric acid is extremely corrosive and destructive, while boric acid is a harmless, inactive substance. 522. Chemical Reactions. — Any change which takes place within a molecule is a chemical reaction. Molecules differ according to the kind, number and relative position of their atoms. Any change in either of these respects is a chemical reaction. The removal of one or more atoms; the addition of one or more atoms; the change of one or more of the atoms by substituting others of a different kind; or any inter- atomic re-arrangement within the molecule by which the rela- tive positions of the atoms is altered — either of these changes is a chemical reaction. 523. The Factors of the Reaction are the molecules decomposed in any chemical reaction. The Products of the Reaction are the new molecules formed by it. 126 CHEMISTRY. Thus when iodine and mercury are triturated together in a mortar to make iodide of mercury, the iodine and the mercury are the factors and the iodide of mercury the product of the reaction which takes place. When a solution of acetate of lead in water is mixed with a water solu- tion of sulphate of zinc, a white insoluble powder precipitates in the liquid, which is sulphate of lead, while water-soluble acetate of zinc remains in solu- tion. In this case the acetate of lead and the sulphate of zinc are the factors of the reaction, and the sulphate of lead and acetate of zinc are its products. 524. Reagents. — The factors of a reaction are also called reagents. But the term reagent is more especially applied to substances employed for the purpose of identifying compounds, radicals or elements, by means of reactions accompanied by striking results and produced by the reagents added for that purpose. Reagents are, therefore, used in analytical processes (S-'5). 525. Chemical reactions are synthetical when their object is to obtain certain products; they are analytical when their object is to identify substances, or detect their presence, or to determine their composition. 526. Synthesis is the formation of compounds by bringing together the radicals necessary to their production under such conditions as are favorable to the synthetical reaction desired. It is the opposite of analysis. Direct synthesis is the formation of but one kind of mole- cules from two or more kinds, as when iodide of mercury is pre- pared from the elemental molecules of iodine and mercury, or when hydrochloric acid and ammonia unite to form ammonium chloride. Indirect synthesis is illustrated by substitution (842) and by double decomposition (529), as in the formation of acetate of zinc from acetate of lead as described in par. 523. More than one kind of molecules are produced by indirect synthesis. 527. Analysis. — The decomposition of chemical compounds for the purpose of determining their composition is called chemi- cal analysis. The analysis is qualitative when the object is simply to iden- tify the radicals or elements of which a substance is composed CHEMISTRY. 127 without attempting at the same time to ascertain the quantities of the component elements or radicals. Quantitative chemical analysis has for its object the determi- nation of the exact quantities of the elements or radicals of which molecules are composed, or the exact quantities of each of several kinds of molecules contained in any mixture, solution, ore, or other mixed substance. 528. Chemical Decomposition is the separation of the constituent radicals or atoms of a molecule. When mercuric oxide is heated above 360 C. (63o° F.) it decomposes into mercury and oxygen, its constituent elements. When calcium carbonate is heated to redness it decomposes, or splits up, into two new compound mole- cules, one of which is calcium oxide and the other carbon dioxide. Chemical decomposition may result from the reaction of two or more substances upon each other, or a re-arrangement of the atoms within a mole- cule may be indirect^ induced bv external causes as by the influence of heat, light, or electricity. 529. Double Decomposition results when two compound molecules are brought together which mutually decompose each other, the reaction giving rise to two or more new compounds. CONDITIONS FAVORABLE TO CHEMICAL REACTION. 530. Actual contact between the particles of matter is necessary to chemical action. 531. Sometimes dry substances may be made to unite chem- ically by simply triturating them together, as when iodine and mercury, or sulphur and mercury, are combined, forming iodide or sulphide of mercury. But this is rarely sufficient. 532. When the factors of the reaction are both gaseous, the chances are usually more favorable to a complete reaction than when they are solid. But oxygen and hydrogen can be mixed and the mixture kept for a long time without any chemical reaction taking place; and a mixture of chlorine and hydrogen can also be kept without change, although the chemical attrac- tion between these gases is very strong. An electric spark, or the application of a lighted match, will quickly cause the gases to unite with violent explosion. The chlorine and hydrogen 128 CHEMISTRY. may react with explosion even by the influence of direct sun- light, but not if the mixture be kept in a shaded place. 533. The most favorable condition in which the factors of the reaction can be as to the state of aggregation is the liquid condition. At least one of them should, therefore, be liquid if possible, and it is still better to have both factors of the reaction in that state. 534. Solids can be rendered liquid either by fusion or by solution, some by one method, some by the other, and still others by either method. But, for the purpose of facilitating chemical reaction, solids are liquefied by fusion only in cases where that is the only practicable means (by reason of the insolubility of the solids or for other reasons). 535. Whenever it is possible to bring the factors of the reaction together in a state of solution, that is the method pur- sued, because in that condition they can be more intimately mixed, and react more freely, uniformly and completely. 536. Heat opposes and often overcomes chemical attraction.. It is, therefore, destructive to most kinds of matter. Compar- atively few kinds of matter can resist the action of strong fire, and numerous substances are decomposed at temperatures not exceeding those readily produced by very simple means. But even when the heat is insufficient to break up a molecule, it, nevertheless, weakens the force with which the atoms are held together, just as heat weakens the cohesion of a mass by increas- ing the distances between the molecules. 537. Thus heat causes chemical reactions in such a way that it seems to aid chemical attraction, although the opposite is true. Heat disrupts existing molecules by causing their atoms to separate from each other. But when the molecules have been decomposed by heat, the atoms of which they were constructed at once rearrange themselves into new molecules capable of resisting the high temperature. Heat indirectly facilitates certain chemical reactions by giving free play to the selective affinities of the atoms whose bonds (615) have been severed by its repellant force. CHEMISTRY. 129 538. Action of heat upon salts. — Salts containing water lose that water when heated. Water of crystallization is usually- expelled already at or even below ioo° C. ; in some cases the salts thus heated dissolve in their water of crystallization before they lose it. Thus a crystal of sodium phosphate is liquefied by heat forming a solution in its water of crystallization. Solu- tion of this kind is called aqueous fusion. Many anhydrous salts undergo fusion at high temperatures; to distinguish this from " aqueous fusion " it is called igneous fusion or dry fusion. Heat causes the decomposition of many salts, especially of those of volatile or unstable acids or bases, except in cases where a strongly positive radical is united to a strongly nega- tive one. . Thus the carbonates are generally readily decomposed by heat, except the carbonates of the alkali metals. Chlorates and nitrates are easily decom- posed by heat, but phosphates and borates resist it: sulphates of the heavy metals are decomposed, but the sulphates of potassium, sodium, barium and calcium are not. 539. Chemism generates heat. — Heat is always liberated by chemical action. More or less heat must frequently be applied to induce chemical action; but the heat afterwards gen- erated by the reaction itself is often sufficient to maintain the energy of chemism. This fact is well illustrated in our experience with the making of fires; the wood or coal must be heated up to a certain point before active combustion goes on, after which the fire continues as long as the supply of fuel and air is sufficient. 540. When heat weakens the atomic attraction within a molecule without breaking it up entirely, the contact of that molecule with another molecule of a different kind may prove to result in a reaction even if such action would not take place without the aid of the heat, both means being necessary to bring it about. 541. Electricity decomposes many chemical compounds, and, therefore, also indirectly causes the formation of other compounds to take the place of those decomposed by it, just as in the case of the decomposition of molecules by heat. 130 CHEMISTRY. 542. Status nascendi. — Chemical reactions take place far more readily when the reacting elements or radicals come into contact with each other at the instant they are liberated from other compounds. Sulphur and hydrogen do not combine directly; but when both are simul- taneously displaced from their compounds — sulphur from iron sulphide and hydrogen from sulphuric acid — they readily unite forming hydrogen sulphide- 543. Molecular hydrogen has no chemical energy ; but atomic hydrogen is energetic enough to decompose nitric acid. If hydrogen be generated in one vessel, and passed through a tube into another vessel containing nitric acid, the gas (molecular hydrogen) will have no effect whatever upon the nitric acid no matter how long continued the current of hydrogen may be. But if hydrogen be slowly generated in the nitric acid itself by dissolving metallic iron in the cold dilute acid, no evolution of gas takes place although hydrogen is set free from the nitric acid, iron taking its place in the molecule of the acid, because the nascent h:drogen — the atomic hydrogen at the moment of its liberation and before its atoms unite to form molecules — decomposes another portion of the nitric acid forming ammonia and water (HN0 3 +4H 3 ==NH S + 3H 2 0) so that the result- ing solution will finally contain not only iron nitrate but also ammonium nitrate. 544. Chemical reactions are also affected by physical forces, both as to their energy and their direction. Cohesion and adhesion exert an important influence upon the course of chemical reactions, in both dry processes and wet pro- cesses (545 to 547). 545. Dry processes or methods are those in which the fac- tors of the reaction are dry substances, either in powder, pieces, or in a state of fusion. Thus when preparations are made by trituration, fusion, exsiccation, cal- cination, sublimation, etc., they are said to be made by the " dry way." 546. Wet processes are those in which one or both factors of the reaction are in a state of solution. All precipitates are prepared by the "wet way," and also many of the water-soluble salts. 547. In wet processes involving double decomposition (529) — that is, when reactions are induced between substances in a state of solution — the direction, velocity, and completeness of CHEMISTRY. 131 the reaction depend greatly upon the relative solubilities of the products. In dry processes where heat is applied, the reaction which takes place, if any, and, indeed, the very question whether any reaction will ensue or not, depends in many cases upon the state of aggregation or cohesion of the possible products — that is, upon whether or not the products are fixed or volatile substances. 548. The predisposing affinity of a third molecule is sometimes of great importance as a means of inducing chemical reaction between two other molecules. In other words A and B may not react with each other in the absence of adventitious influences, but may do so in the presence of another body, C, which stands ready to react with one of the products of the reaction between A and B. The general tendency of all matter is to form as neutral and permanent molecules as possible under the conditions under which it is placed. A negative radical, therefore, determines or predisposes the formation of a positive one with which it may be united, and vice versa, in order that the final result may be a more firmly united and stable molecule. Strong acids and strong alkalies exert a destructive influence upon many neutral substances for this reason. In chemical reactions which are accompanied by a change of the valence of elemental radicals, the cause of such a change can hardly be looked upon as any other than this predisposing affinity which compels the formation of the strongest possible compound radicals, that can be formed out of the atoms taking part in the reaction. CHAPTER XXVII. THE LAW OF OPPOSITES IN CHEMISTRY. 149. The opposite properties of acids and alkalies are among the most striking facts of chemistry. The destructive properties of both have been known since ancient times, and are so pronounced and so important as to be familiar to most per- 132 CHEMISTRY. sons of the present time. The sour, corrosive properties of the stronger acids are opposite to the caustic properties of the alka- lies, and acids and alkalies neutralize each other, so that the properties of both are nullified. These facts were observed long before chemistry assumed the dignity of a science. 550. Acetic acid in the form of vinegar is mentioned in the books of Moses, and was used in medicine by Hippocrates and Dioscorides. Nitric acid was made by Geber in the seventh century, and "muriatic acid " was also known at a very early period. The Arabs knew how to make "aqua regia," which is a mixture of nitric and muriatic acids, and they were acquainted with the fact that gold could be dissolved in that mixture. " Oil of vit- riol," which is an old name for sulphuric acid made from "green vitriol," was made as early as the 15th century. 551. The lye of wood ashes was well known, and the solid "fixed alkali," which was obtained from it (the impure " pot- ash"). Lime, too, has attracted attention, and its effect in increasing the alkaline character of potash and soda. Sodium carbonate is referred to in the Old Testament, and the ancients applied the name nitrum to it. Ammonia was recognized as an alkali, being known as a constituent of urine after standing (and we still hear the expression "chamber-lye"). It was also made from ammonium chloride, known at least as early as in the 7th century. Later, potash was called "alkali vegetabile," soda (sodium carbonate) was named "alkali minerale," and ammonia, "alkali volatile." 552. The fact that acids and alkalies neutralized each other's corrosive properties was too striking to remain unobserved. Acid and lye saturated each other and neutral compounds resulted which had properties entirely different from those of either of the materials which were mixed. When vinegar was poured upon chalk, the chalk was dis- solved and effervescence took place. The gas which caused this effervescence as it passed off received later the name of "acid of air." CHEMISTRY. 133 553. But it was further known that some acids and some alkalies are stronger than other acids and alkalies, respectively. It was recognized that sulphuric acid ("oil of vitriol ") would decompose nitre, whereby nitric acid was obtained, and that it would also decompose common salt, whereby muriatic acid was gotten. It is true the early chemists did not know the acids, bases and salts by their present names, and did not know their chem- ical composition and formulas; but they knew their striking dif- ferences. 554. The metals potassium and sodium were separated from the fixed alkalies by means of electricity by Sir Humphrey Davy; and the discovery of oxygen and chlorine, and of the true nature of combustion, led to a classification of the elements into the metallic and non-metallic groups, which further empha- sized the opposite character of their most important compounds. 555. Acids (883) and bases (874) were carefully studied. It was discovered that both classes of compounds, as a rule, con- tained oxygen ; but that the metallic oxides (846) were basic (848), whereas the oxides of the non-metallic elements (847), con- taining a comparatively larger proportion of oxygen, produced acids. Consequently the salts were assumed to be composed of metallic oxides with the anhydrides of the non-metallic elements, and potassium sulphate, which is now written K 2 S0 4 , was then written KO. S0 3 . What was then called an acid is now called an anhydride. But the main fact is — they were of opposite chemical properties and neutralized one another. 556. Simultaneously with the introduction of the balance and the discovery of oxygen came the researches and discoveries of Volta and Galvani in the field of electricity. The intimate relations between chemism and electricity were recognized. Not only was the galvanic current produced and maintained by the aid of chemical reactions, but the current seemed to have an almost unlimited power to resolve chemical compounds into two constituents; one of which was invariably 134 CHEMISTRY. attracted to the positive electrode and the other to the negative electrode. Salts were thus-decomposed with the result that the acid collected at the positive pole, and the base at the negative pole. Other compounds have been decomposed in the same way and with similar results. 557. We have before learnt (443) that electricity is devel- oped by chemical action, and that the electricity thus developed is cal led galvanic or voltaic electricity, being so named after Gal- vani and Volta. We have also seen (435) that electricity exhibits in a striking manner phenomena of attraction and repulsion, because it has two opposite states, one called positive electricity and the other negative electricity, and that electricity is a polar force with posi- tive polarity and negative polarity (449). It has also been stated that bodies charged with like elec- tricities repel each other, while two bodies of opposite electrical polarities attract each other (440). 558. No chemical reaction takes place without the develop- ment of electricity. It is also known that chemical reactions are essential to the production of voltaic action. The energy of the electric current is proportionate to the energy of the chemical action, and the direction of the one is dependent upon the direction of the other. 559. Electrolysis. — A great number of compounds can be decomposed into their immediate constituents by means of electricity. This is called electrolysis. The various compounds which can be decomposed by electrolysis are called electrolytes. 560. Electrolytic decomposition resolves the constituents of the electrolyte into two groups, one of which is attracted to the negative pole of the battery, the other passing to the positive pole. 561. The same current of electricity, transmitted succes- sively through different electrolytes, decomposes each in the proportion of their respective chemical equivalents. The energy of the electric current is proportionate to the energy of the chemical action which produces it. CHEMISTRY. 135 562. When a chemical compound is decomposed by an elec- tric current, the matter attracted to the positive pole is said to be electro- negative, and that attracted to the negative pole is electro-positive . 563. The foregoing facts point strongly to a law of oppo- sites in chemistry analogous to the law of opposites which is so strikingly manifest in the phenomena of electricity. 564. Electro-chemical Polarity. — Radicals are of two opposite kinds as to the quality of their chemism, namely, posi- tive and negative radicals. Positive radicals unite with negative radicals, and negative radicals unite with positive radicals ; but one positive radical does not unite with another positive radi- cal ; no radical unites with another radical of the same electro- chemical polarity. 565. Positive radicals are those which are attracted to the negative pole in electrolysis They form compounds with the negative radicals. 566. Negative radicals are those which are attracted to the positive pole in electrolysis. They unite with positive radicals to form chemical com- pounds. 567. Electro-chemical Theory. — The phenomena of chem- ism have been attributed to electrical attraction between atoms and between radicals. That strong grounds for such an hypothesis exist is sufficiently evident from the foregoing. There are, however, a large number of compounds which do not seem to be susceptible of electrolytic decomposition. The electro-chemical theory, and the idea of simple and compound rad- icals which is inseparable from it, do not so directly and plainly account for substitution, which results in changes within the radical, leaving the external behavior of the latter unaffected. Yet, until a better hypothesis shall have been presented, the obviously intimate relations between electricity and chemism are recognized, simple and compound radicals are referred to as relatively electro-positive or electro- negative, chemical combination is regarded as dependent upon the opposite electro-chemical properties of atoms and compound radicals, and the general chemical character and conduct of compounds are supposed to be determined by the electro-chemical characters and relations of their constituents. 136 CHEMISTRY. Berzelius assumed that atoms were endowed with electric polaiity and that when two substances combine chemically their opposite electricities neutral- ize each other. This electro-chemical relation between acid-forming and base- forming simple or compound radicals applies to both inorganic and organic chemistry. 568. Molecules formed by the union of strong electro-posi- tive radicals with strong electro-negative radicals offer greater resistance to change than other molecules. Very complex molecules, containing a large number of atoms, and composed of several different compound radicals, are more frequently unstable than those of more simple structure. 569. But the terms " positive " and " negative," as applied to radicals, are only relative terms, for any one radical may be electro-positive with reference to some and electro-negative to other radicals of other kinds. Thus when nitric anhydride, which is a compound of nitrogen and oxy- gen, is decomposed by an electric current, its nitrogen is collected at the negative pole and its oxygen at the positive pole of the battery; but when ammonia, a compound of nitrogen and hydrogen, is similarly decomposed, the nitrogen passes to the positive pole, the hydrogen going to the opposite electrode. Sulphur is found to be electro-positive in sulphuric anhydride, a compound of sulphur and oxygen, but negative in its compounds with the metals. 570. The metals are, as a rule, electro-positive. Sulphuric acid is hydrogen sulphate. The hydrogen in it is positive; but zinc is relatively a stronger positive radical and therefore takes its place when zinc is put into the acid. 571. Silver is separated from a solution of silver nitrate by metallic lead, the lead taking the place of the silver in the solution. If the separated silver be filtered out and a piece of copper put in the solution of the lead nitrate, the lead will in turn be separated out by the copper, and the copper can be displaced in a similar way by either iron or zinc. 572. The Electro-chemical Series. — Berzelius arranged the elements known in his day into a series according to their relative electro-chemical position, beginning with the strongest electro-negative element and ending with the strongest electro- positive element. Each element in the series is positive toward any element preceding it, and negative to any element below it. An abbreviation of it is given here: CHEMISTRY. Negative end — Atoi?iic weight. Oxygen II. 16. Sulphur II, IV, VI. 3 2 - Nitrogen I, III, V. 14. Fluorine I. 19. Chlorine I to VII. Bromine I to VII. ► Halogens. 35-45 80. Iodine I to VII. 126.85 Phosphorus I, III, V. 3i. Arsenic I, III, V. 75. Chromium II, IV, VI. 5 2 - Boron III. 1 1. Carbon II, IV. 12. Antimony III, V. 120. Silicon IV. 28.4 — Hydrogen I. + -1. Gold I, III. 1 197.3 Platinum II, IV. Noble Mercury II. | metals. i95- 200. Silver I, III. Copper II. 108. 63-4 Bismuth III, V. 209. Tin II, IV. 119. Lead II, IV. 207. Cobolt II, IV. 59- Nickel II, IV. 58-7 Iron II, IV, VI. 56. Zinc II. 65.3 Manganese II, IV, VI. 55- Aluminum IV. 27. Magnesium II. 24-3 Calcium II, IV. \ Alkaline 40. Strontium II, IV. > earth 87.6 Barium II, IV. ) metals. 137. Lithium I. -\ Sodium I, III. ( Alkali Potassium I. Ill, V. J metals - 7. 23- 39- Positive end 4- 137 138 CHEMISTRY. 573. Upon an inspection of the preceding table it will be found that oxygen is the strongest electro-negative element, with sulphur as second; and that potassium is the strongest electro-positive element (of the more common elements) with sodium as second. Oxygen forms with the negative elements (above hydrogen) acid forming oxides; with hydrogen it forms an absolutely neutral oxide, water; and with the positive elements (below hydrogen) it forms basic oxides. The com- pounds of the halogens with hydrogen are in several respects like the true acids. The compounds formed by sulphur with the other elements are analo- gous to those formed with them by oxygen. Oxygen and sulphur together form an oxide which produces (with water) the strongest acid known — sul- phuric acid. Oxygen and sulphur are dyads and the halogens are monads. The polyvalent negative elements, which are typically represented by nitrogen and carbon, are remarkable for the great number of compound radicals which they form with oxygen and hydrogen. Hydrogen and oxygen form water. But no less remarkable is the com- pound radical (HO) called hydroxyl, formed by one atom of each of these wonderful elements. Hydroxyl is contained in all acids, bases and alcohols. Arsenic, chromium and antimony (above hydrogen) are of a metallic character, but nevertheless form acids. Below hydrogen we find first gold and platinum which are very weak positive elements. The polyvalent elements bismuth and tin possess analo- gies with nitrogen and carbon, respectively, and form acids as well as bases. At the lower end of the series we have the strongest base-forming metals. 574. The student should study this chapter again after he has learned the remaining chapters on chemistry, that he may recognize the fact that there is a self-evident intimate connection between the electro-chemical character of the elements on the one hand and their valence and atomic weights on the other. But the student must not suppose that he can employ the electro-chem- ical series as a safe guide in pre-determining the course of chemical reactions, or the relative electro-chemical character of compound radicals. An intelli- gent advanced student may often find satisfactory explanations of estab- lished facts by studying such tables as this; but all students must bear in mind at all times that ascertained facts stand both before and after theories, however attractive and really helpful the theories may be. Facts lead to theories, and theories in turn lead to other facts; but experimental science discovers facts independently of theory, and new theories are evolved which supplement, modify, or even supplant previous theories, while the facts stand. Only the learned and experienced may make, apply, analyze, and unmake theories. Students, however, should learn to understand accepted funda- mental theories, and their relations to the facts of experience, as far as they can. CHEMISTRY. 1 39 CHAPTER XXVIIi. FIXED COMBINING PROPORTIONS AND THE ATOMIC THEORY. 575. A vast number of chemical compounds have been examined, made, and unmade. Weighed quantities have been decomposed into their constituent elements, and the respective weights of these elements also ascertained and found to account for the whole. The same elements in the same proportions have also been put together again and caused to unite, the product being not only the same compound which had before yielded these elements when it was decomposed, but the weight of the product has been found to be exactly the same as the sum of the weights of the elements. Substances have been composed and decomposed in the same manner, and the factors and products weighed, without dealing with elemental mole- cules, and the results have been as absolute and invariable. Hence, nothing is lost in any chemical reaction, whether the reaction be synthetical or analytical. 576. Water has been repeatedly decomposed. It has been invariably found to yield by its decomposition two elements, oxygen and hydrogen, and nothing else. Water has also been repeatedly made out of oxygen and hydrogen, and can be made of nothing else. Thus it has been conclusively proven that water is composed of hydrogen and oxygen. Numerous other substances have been decomposed and composed, many times over, and have been proven, analytically and synthetically, to consist invariably of the same elements. In no case has a different result been reached. Hence, any given kind of matter always contains the same elements 577. It has been further demonstrated that water con- tains its oxygen and hydrogen invariably in the proportion of 88.89 P er cent, by weight of the oxygen and ii.n per cent, by weight of the hydrogen. In other words ioo pounds of water always contains 88. 89 pounds of oxygen and n. 11 pounds of hydrogen. 140 CHEMISTRY. If 88.89 pounds of oxygen and 11. 11 pounds of hydrogen be made to unite by chemism, the product is exactly 100 pounds of water. If any more than 88.89 pounds of oxygen be used' with ri.ii pounds of hydrogen, all of the excess of oxygen above the 88.89 pounds will remain as still oxygen, but 100 pounds of water will be formed; if less oxygen is used, a corresponding quan- tity of hydrogen will be left over, and a correspondingly smaller amount of water will be obtained. Hydrochloric acid is composed of 1 pound of hydrogen and 35.45 pounds of chlorine, making 36.45 pounds of the acid ; and chlorine and hydrogen do not unite in any other proportions. If you try to combine 2 pounds of hydrogen with 35.45 pounds of chlorine you will have just I pound of hydrogen left over, etc. When calomel is decomposed and its constituent elements weighed it is found that 235.45 pounds of calomel contain 200 pounds of mercury and 35.45 pounds of chlorine. If you combine 200 pounds of mercury with 35.45 pounds of chlorine, you will get just 235.45 pounds of calomel. But if you combine 200 pounds of mercury with 70.9 pounds of chlorine, you will not get calomel at all ; you will, however, get just 270.9 pounds of corrosive sublimate. Numerous other substances have been decomposed and produced with the result that the proportions of the component elements have been found to be invariable. In no case have the results been otherwise. Therefore all chei?iical compounds con- tain fixed proportions by weight of their component elemen 578. But it happens frequently that two elements combine with each other in more than one ratio. In every such case, however, the product is a different substance whenever the pro- portions of the component elements are different; and the proportions necessary to form any particular substance are invariable. 579. The metal manganese unites with oxygen in five differ ent proportions, as follows: 55 pounds of Manganese unites with 16 pounds of oxygen. 55 " " " " 24 55 •' » <• << 32 » 5 5 « «< « « 48 « 55 " .'•' " " 56 CHEMISTRY. 141 If you now divide the pounds of oxygen in each case by the smallest number (16), you get the quotients i, i%, 2, 3, and Nitrogen unites with oxygen also in five proportions : 14 pounds of nitrogen unites with 8 pounds of oxygen 14 " " " " 16 " 14 " " " '« 24 14 " " " 32 14 " " " 40 If you again divide the number of pounds of oxygen by the smallest number (8), you will get 1, 2, 3, 4 and 5. Chlorine forms four oxides : 709 pounds of chlorine unites with 160 pounds of oxygen. 709 " " " " 480 " " 709 " " ' " 800 " " 709 " " "1,120 " " Divide the pounds of oxygen as before ■ the quotients are 1, 3, 5 and 7- Three chlorides of manganese are known: 550 pounds of manganese unites with 709 pounds of chlorine. 550 " " " " 1,063.5 550 " " ' 1,418 Divide the pounds of chlorine as before the oxygen and you get the numbers 1, 1% and 2. Compare these tables with each other and you will further find that 550 pounds of manganese unites with 160 pounds of oxygen, but with 709 pounds of chlorine; that 709 pounds of chlorine also unites with 160 pounds of oxygen. 580. The simplicity of these proportions is found to extend to all chemical compounds. How is it to be accounted for? If it be assumed that the elements are not divisible without limit, but that each element consists of indivisible particles hav- ing a fixed weight, that assumption will explain it all satisfac- torily No other theory has ever been proposed which does account for the fixed combining proportions observed in all chemical compounds. 142 CHEMISTRY. 581. It has been stated that it takes 8, 000 ,000,000 molecules of water to make a particle of water of sufficient size to be seen by the aid of one of the best modern microscopes. Sir William Thomson says: " If we conceive a sphere of water of the size of a pea to be magnified to the size of the earth, each molecule to be magnified to the same extent, the magnified structure would be coarser grained than a heap of small lead shot, but less coarse-grained than a heap of cricket-balls." It has been estimated that the mean diameter of molecules is so small that if 500,000 of them were placed in a row, the row would be only yo^ts mcn m length. It has also been said that the molecules of hydrogen are about Tnnnnnro" °f an i ncn a P art from each other. Each molecule of hydrogen con- tains two atoms. But these dimensions are beyond intelligent comprehension. Atoms are so small that their diameter and absolute weight can not be determined, and for purposes of argument we may as well assume that they weigh pounds as that they weigh an infinitesimal fraction of a milligram. The relative weights of atoms are believed to be correctly determined. 582. If we assume, then, for argument's sake, that an atom of hydrogen weighs 1 pound, an atom of oxygen 16 pounds, nitro- gen 14 pounds, chlorine 35.45 pounds, manganese 55 pounds, and mercury 200 pounds, and that these atoms are indivisible — then the definite combining proportions observed in the examples given in paragraphs 577 and 579 will not only become intelligi- ble, but they could not be otherwise than fixed. Peroxide of hydrogen will be obtained when 1 pound of hydrogen forms molecules with 16 pounds of oxygen; but 2 pounds of hydrogen forms water with 16 pounds of oxygen; 16 pounds of oxygen unites with 14 pounds of nitrogen to form nitrogen dioxide; 14 pounds of nitrogen unites with 3 pounds (3x1) of hydrogen to form ammonia; 14 pounds of nitrogen unites with 106.35 pounds (3x35.45) of chlorine forming nitrogen chloride; 3 pounds of hydrogen and 106.35 pounds of chlorine unite to form hydrochloric acid; 106.35 pounds of chlorine united with 55 pounds of manganese will form manganic chloride; 55 pounds of manganese unites with 16 pounds of oxygen forming manganous oxide; 16 pounds of oxygen unites with 200 pounds of mercury to form mer- curic oxide; and 200 pounds of mercury unites with 35.45 pounds chlorine to form calomel, or with twice that amount of chlorine to form corrosive subli- mate. 583. The Atomic Theory. — On account, then, of the fixed combining proportions (577 and 579) it is assumed that all matter is divisible into small particles called atoms which are themselves indivisible CHEMISTRY. 143 having fixe a weights (580 and 582). This theory was proposed by Dalton. 584. Atomic Weights, — The smallest weight of any ele- ment which can enter into the formation of a compound is its atomic weight. Atomic weights are expressed in hydrogen units; the relative weight of any atom as compared to the weight of the atom of hydrogen (H = 1), therefore expresses its atomic weight. Practically the smallest relative quantity by weight which has been found in the various compounds of an element is assumed to represent its atomic weight. This is the quantity by weight which unites with or can take the place of one atom of hydrogen. Whether or not the numbers called atomic weights actually represent the relative weights of atoms, they serve to express truthfully the definite and multiple proportions in accordance with which all compounds are formed. The molecular weight being known and also the number of atoms in the molecule the atomic weight is found by dividing the molecular weight by the atomicity of the molecule. 585. Dalton's Law of Multiple Proportions — When- ever any two ele?nents combine in more than one proportion, the several compou?ids formed by these elements co?itain simple multiples of the atomic weights of both constituents. Thus if A and B unite in several different proportions, their atoms unite in the numerical ratios of 1 to 1, or 1 to 2, or 1 to 3, or 1 to 4, or 1 to 5, or 1 to 6, or 2 to 2, or 2 to 3, or 2 to 4. or 2 to 5, or 2 to 6, or 2 to 7, or 3 to 4, or 3 to 5, or 3 to 7, or some other simple ratio. 586. Dulong and Petit, in 1819, proposed the law that all atoms have the same capacity for heat. • In other words, it requires exactly the same amount of heat to raise the temperature of any atom one degree, without reference to its kind. Their proposition was based upon a series of investigations by which it became evident that a simple proportion exists between the specific heats and the atomic weights of the elements. These were found to be inversely proportional. 144 CHEMISTRY. 587. Specific heat is the relative quantity of heat necessary to raise the temperature of one weight unit of any substance one thermal degree. Specific heat is expressed in units of the specific heat of water, which is taken as the thermal standard. Thus the quan- tity .of heat necessary to raise one weight unit of water one degree is the specific heat of water, and being chosen as the standard of comparison it is == 1. ■ But mercury requires only yf^ffo as much heat as water does to raise the same quantity of it one thermal degree, and, therefore, the specific heat of mercury is 0.0319. 588. Investigations by Neumann and Regnault, in 1831, proved that the specific heats of compounds are inversely propor- tional to their molecular weights. 589. Thus, the specific heat of elements is inversely as their atomic weights, and the specific heat of compounds inversely as their molecular weights. After further investigations by Regnault and others, with a great variety of compounds, it was concluded that all atoms, free or combined, have the same capacity for heat. These valuable discoveries afforded a new means of finding or verifying atomic and molecular weights. 590. Deduction of Atomic Weight from Specific Heat. — The atomic weights of elements may be verified by examining the specific heats of their solid compounds. When the specific heat of any elementary body is multiplied by its atomic weight the product is a constant number. Owing to the unavoidable liabili- ties to error in such difficult determinations, the specific heats and the atomic weights found by the best methods known are not absolutely correct, and hence the product of the atonic weight by the specific heat varies somewhat, but the mean is 6.40. Whenever, therefore, the product varies considerably from that mean, one or both factors are assumed to be wrong; and should the product be only one-half of 6.40, or should it be twice 6.40, the inference would be that the atomic weight used is double or one-half of the actual. 591. Atomic Heat. — The number obtained by multiplying the specific heat of any element by its atomic weight is called its atomic heat. CHEMISTRY. 145 As already stated, it is near 6.4. All elements are assumed to have the same atomic heat under certain conditions. [The molecular heat divided by the number of atoms contained in the molecule will also give the atomic heat.] 592. The atomic heat of any element (6.4) divided by its specific heat will give its atomic weight; and the atomic heat divided by the atomic weight will give the specific heat. The specific heat multiplied by the atomic weight gives the atomic heat. 593. Molecular Weight. — The molecular weight of any substance, or the weight of its molecule, is the sum of the weights of its constituent atoms. It is, therefore, found by- adding these together. 594. Molecular Heat. — The number obtained by multiply- ing the specific heat of any compound by its molecular weight is called its molecular heat. It is the sum of the atomic heats of the atoms it contains. The molecular heat of any compound divided by the number of atoms contained in the molecule will give as a quotient the mean of the atomic heats of the elements, which, with rare exceptions, is about 6.4 (590) 595. The number of atoms contained in any molecule may, therefore, be readily ascertained if its specific heat and molecular weight are known; for if the molecular heat is divided by 6.4 (the atomic heat) the quotient is the num- ber of atoms in the molecule. It is of course also found by dividing the molecular weight by the atomic weight. 596. The specific heat of a substance may be found by dividing the molec- ular heat by the molecular weight. 597. Combination by volume in simple proportions. Gay Lussac found that gases always combine in simple proportions by volume, and also that the volume of the product in the gas- eous state bears a simple relation to the volumes of the con- stituents. One volume of hydrogen unites with one volume of chlorine, producing two volumes of hydrochloric acid; two volumes of hydrogen unite with one volume of oxygen, producing two volumes of water-vapor; three volumes of hydrogen and one volume of nitrogen unite to form two volumes gaseous am- monia; etc. As elements combine in fixed proportions by weight, and, in the gaseous state, also in fixed proportions by volumes, it fol- lows that the weights of equal volumes of all gases bear the same relation to each other as do the combining weights of the 146 CHEMISTRY. elements, and if the atomic theory is correct the number of atoms contained in a given volume of any gas bears a simple relation to the number of atoms contained in the same volume of any other gas. 598. In paragraph 582 it was shown that the relative com- bining weights, or atomic weights, of the four most important caseous elements are as follows: Hydrogen 1 Nitrogen 14 Oxygen 16 Chlorine . 35.45 When the weights of equal volumes of these gases are com- pared it is found that the above figures, representing their atomic weights, also express the relative weights of equal vol- umes. Thus one quart of nitrogen weighs 14 times as much as a quart of hydrogen, a quart of oxygen weighs 16 times as much as a quart of hydrogen, and a quart of chlorine gas 35.45 times as much as a quart of hydrogen. As the specific weight of any kind of matter in a gaseous state, called its vapor density, is expressed in hydrogen units, the specific weight of hydrogen being taken as 1, we find that the vapor densities of hydrogen, nitrogen, oxygen and chlorine are exactly expressed by their atomic weights. 599. Avogadro's Law. — The simple relations between the atomic weights and vapor densities of the elements of course appear also when the molecular weights are compared with the vapor densities, for the molecules of the elements are made up of a small number of atoms and the molecular weight is the sum of the weights of the atoms. Thus: ELEMENT. Vapor Density. Atomic Weight. Molecular Weight. Hydrogen 1 1. 16 2 28 Oxygen 16 32 Chlorine If comparisons be made of the weights and vapor densities of compound molecules, the same simple relations are found: CHEMISTRY. 147 Compound. Molecular Weight. Water Hydrochloric Acid . Sulphur Dioxide. .. Ammonia Marsh-gas Chloroform Avogadro accordingly proposed the hypothesis: Equal vol- umes of all gases contain the same number of molecules. 600. If the molecular weight of any substance be divided by the vapor density (expressed in hydrogen units), the quotient should always be 2. The vapor density multiplied by 2 should give the molecular weight; and the molecular weight divided by 2 should give the vapor density. [But Crafts and Meyer reduced the vapor density of iodine by heating until it was but one-half of the normal, or only one-fourth of the accepted molecular weight. That makes it appear as if iodine was then in an atomic condition.] 601. It is easily shown that the molecuie of hydrogen con- tains at least two atoms, and for good reasons it is assumed that tbe number does not exceed two. Hydrogen having been chosen as the unit ot atomic weight, its molecular weight is 2, and if Avogadro's hypothesis is applied it is found that the molecular weight of any substance coincides with its vapor density multiplied by 2. It follows that the vapor density of any substance is expressed by one- half its molecular weight. 602. As it follows from the atomic hypothesis that the num- ber of atoms contained in any elemental molecule is obtained by dividing the molecular weight by the atomic weight, therefore : — The atomic weight of all elements having diatomic molecules (2 atoms in each molecule) coincides with the vapor density; if the molecule contain but one atom the atomic weight is equal to twice the vapor density; in elements with triatomic molecules (3 atoms in each molecule) the atomic weight is equal to two-thirds of the vapor density; in elements with tetratomic molecules (4 atoms in each molecule) the atomic weight is equal 148 CHEMISTRY. to one-half of the vapor density; and in elements with hexa- tomic molecules (6 atoms in each molecule) the atomic weight is equal to one-third of the vapor density. 603. If it be assumed that one measure of hydrogen contains 1,000 mole- cules of hydrogen, one measure of oxygen contains the same number (599). Two measures of hydrogen, containing 2,000 molecules, would contain 4.000 hydrogen atoms, and one measure of oxygen would contain 2,000 oxygen atoms, for the molecules of hydrogen and oxygen have both been found to be diatomic. The total number of atoms, then, contained in the two measures of hydrogen and one measure of oxygen would be 6. coo. When combined they form two measures of water vapor. According to Avogadro's law these two measures must contain the same number of molecules as the two measures of hydrogen, or 2,000. Now, as these 2.000 molecules of water were formed out of 4000 atoms of hydrogen and 2,000 atoms of oxygen, there must be 2 atoms of hydrogen and 1 atom of oxygen in each water molecule, which is exactly what the molecule of water has been shown by other means to contain. The fact that 2 measures of hydrogen and 1 measure of oxygen form only 2 measures of water vapor, is accounted for by the fact that the water molecules contain 3 atoms each while the hydrogen and oxygen contain only 2 atoms each 1 volume of Hydrogen and 1 volume of Chlorine produce 2 volumes of Hydrochloric Acid gas 2 volumes of Hydrogen and 1 volume of Oxygen produce 2 volumes of Water vapor. 3 volumes of Hydrogen and 1 volume of Nitrogen produce 2 volumes of gaseous Ammonia. Hydrochloric acid is diatomic, and, therefore, requires only two volumes of diatomic elements to produce the same number of molecules. The molecule of water is triatomic, and, therefore, requires three volumes of diatomic elements to produce the same number of molecules. Ammonia is tetratomic, and, therefore, requires four volumes of diatomic elements to produce the same number of molecules. CHEMISTRY. I49 604. Table of Atomic Weights used in this book. ( H=I -) The names of elements occurring in pharmacopceial, medicinal chemicals are printed in heavy-faced type. Name. Aluminum. . Antimony. . . Arsenic Barium Bismuth — Boron Bromine — Cadmium Caesium Calcium Carbon Cerium Chlorine Chromium. . Cobalt Columbium 1 ) Copper Didymium 2 ) . Erbium Fluorine. . . . Gallium Germanium . Glucinum 3 ). . Gold Hydrogen 4 ). . Indium Iodine Iridium Iron Lanthanum. . Lead Lithium Magnesium . Manganese. Mercury Symbol Al Sb As Ba Bi B Br Cd C s Ca C Ce CI Cr Co Cb €u Di Er F Ga Ge Gl Au H In I Ir Fe La Pb Li Mg Mn Hg Atomic Weight. 27. 120. 75. 137. 209* 11. 79.8 111.5 132,7 40. 12. 140. 35.4 52. 58.6 93.7 63.2 142. 166. 19. 70. 72.3 9. 196.7 1. 113.6 126.5 192.5 56. 137.9 206.4 7. 24.3 55. 1 200. Name. Molybdenum Nickel Nitrogen Osmium Oxygen .... Palladium. . . Phosphorus . Platinum. . . . Potassium . . Rhodium. . . . Rubidium . . . Ruthenium. . Samarium . . . Scandium . . . Selenium. . . . Silicon Silver Sodium Strontium. . . Sulphur — Tantalum . . . Tellurium . . . Terbium Thallium. . . . Thorium .... Tin Titanium. . . . Tungsten. . . . Uranium Vanadium. . . Ytterbium. . . Yttrium Zinc Zirconium. . . Symbol. Mo Ni N Os Pd P Pt K Rh Rb Ru Sm Sc Se Si Ag Na Sr S Ta Te Tb Tl Th Sn Ti W U V Yb Yt Zn Zr Atomic Weight. 96. 58.6 14. 190.3 16. 106.4 31. 194.3 39. 103.5 85. 101.4 150. 44. 79. 28.3 107.7 23. 87.3 32. 182. 125. 159. 203.7 232. 119. 48. 183.6 239. 51. 172.6 89. 65.1 90.4 1) Has priority over Niobium. 2) Now split into Neo-and Praseo-Didymium. 3) Has priority over Beryllium. 4) Standard, or basis of the system. 150 CHEMISTRY. CHAPTER XXIX. VALENCE. 605. We have said that atoms unite with each other to form molecules. All atoms of the same kind have the same chemi- cal saturating power ; that is, the quantity of the chemism of any- one atom is exactly the same as the quantity of the chemism of any other atom of the same kind. One atom has f he same com- bining value as another atom of the same kind. It is also found that one kind 'of atoms may have the same combining value or saturating power as atoms of a certain other kind. Thus, chlorine atoms and hydrogen atoms have the same combining value, so that one. atom of chlorine combines with one atom of hydrogen, both atoms being thereby saturated, so that not more than one atom of each kind can unite, and so that no other atom of any kind can unite with one atom of chlorine and one atom of hydrogen together. This equality of combin- ing power, or chemical saturating capacity, or atomic value, or combining value, is also shown by the atoms of potassium and chlorine, by calcium and oxygen, silver and iodine, zinc and sul- phur, boron and nitrogen, etc. In all these cases one atom of one kind unites with one atom of the other kind forming a molecule incapable of combining with any other atom or radi- cal. The chemism of the atoms of the molecule is, therefore, exhausted, saturated, satisfied, or neutralized. 606. But an atom of chlorine has only one-half the value of an atom of calcium, for two atoms of chlorine are always required to saturate (or form a molecule with) one atom of cal- cium. One atom of oxygen has twice as great combining power as an atom of potassium, and twice the value also of an atom of hydrogen, for one atom of oxygen will satisfy at once one atom of each of potassium and hydrogen. One atom of nitrogen demands three atoms of hydrogen — no more, and no less. If we use the letter H to represent an atom of hydrogen, O to represent an atom of oxygen, N to represent an atom of nitrogen, C to represent an atom of carbon, and append numerals CHEMISTRY. 151 to represent any number of atoms exceeding one, we shall be able to write the molecular formulas (630) of hydrochloric acid, water, ammonia, and marsh-gas. HC1 • H 2 H 3 N H 4 C Hydrochloric Acid Water Ammonia Marsh-gas These formulas show that if the combining value of the hydro- gen atom is expressed by 1, then the value of the oxygen atom is 2, that of the nitrogen atom is 3, and that of the carbon atom 4. 607. Radicals (519) unite with each otherin accordance with their relative combining or saturating power, which is called their valence. One or two atoms of one kind may, apparently, be capable of saturating one or two, three, four, five, six or seven atoms of another kind; or tw r o atoms of one kind may saturate three or five atoms of another kind. The same is true of compound radicals. Thus, one atom of hydrogen binds one other atom of hydrogen; but one atom of oxygen binds two atoms of hydrogen; one atom of nitrogen satu- rates three atoms of hydrogen; one atom of carbon satisfies four of hydrogen; and, while the atoms of chlorine and hydrogen are of equal value (as one atom of either binds one atom of the other), an atom of tantalum is of equal value with five atoms of chlorine; one atom of tungsten satisfies six atoms of chlorine; and the atomic value of chlorine in one of its compounds with oxygen appears as if it were seven times that of hydrogen. 608. Valence is also called " atomic value,'' "quantivalence," "equivalence" [and sometimes also "atomicity"*]. 609. Valence is expressed in hydrogen units. Hydrogen has been adopted as the standard of comparison for this pur- pose because the atom of hydrogen has a smaller valence than any other atom except those having the same value as itself. Therefore the valence of a radical may also be said to be rep- resented by the number of atoms of hydrogen which it satis- fies, or equals in combining power, or for which it can be exchanged. Hydrogen, being the unit, has a valence of one; any other radical uniting with, or capable of taking the place of, two atoms * The term atomicity has also been used to express the number of atoms contained in an elemental molecule (471). 152 CHEMISTRY. of hydrogen has the valence 2; a radical which takes the place of, or satisfies, three atoms of hydrogen, has a valence expressed by the number 3, etc. 610. Many elements and radicals do not unite with hydrogen; but they do unite with other radicals whose valence has been ascertained, and the valence of all radicals must be determined, not with reference to their hydro- gen compounds merely, but to their compounds generally, and especially with regard to their most important and best known compounds, whatever these may be. Thus, not only hydrogen compounds, but also oxides, chlorides and other molecules must be studied in order to correctly determine the valence of any element or compound radical. 611. Artiads and Perissads. — Radicals whose valence is expressed by an even number, as 2, 4, or 6, are called artiads; while radicals of an uneven valence, as 1, 3, 5, or 7, are called perissads. 612. The artiads are more numerous than the perissads. Hydrogen, and all other radicals having the same valence, are called monads, and are univalent; radicals which unite with or replace two hydrogen or chlorine atoms are called dyads and are bivalent; those that satisfy or replace three hydrogen or chlorine atoms are called triads and are trivalent; those equal in value to four hydrogen or chlorine atoms are tetrads and quadrivalent; radicals whose atomic value is five are called pentads, and they are quinquivalent; those whose valence is six are hexads and sexi- valent; and radicals with an atomic value of seven are heptads and septivalent. 613. The valence of chlorine is 1, because 1 atom of chlo- rine will unite with and saturate 1 atom of hydrogen, or will replace it. Chlorine is, accordingly, like hydrogen, a monad and univalent. Iodine, bromine and fluorine are also monads for the same reasons. Potassium, sodium, lithium and silver are monads, too, because 1 atom of any oneof them will take the place of 1 atom of hydrogen, and because either of them will unite with and saturate 1 atom of chlorine, iodine or bromine. Oxygen is a dyad, for 1 atom of it saturates 2 atoms of hydrogen. Negative nitrogen is a triad, because 1 atom of it will satisfy 3 atoms of hydrogen. CHEMISTRY. Carbon has the valence of a tetrad, for i atom of it saturates 4 atoms of hydrogen. For similar reasons other radicals are pentads, hexads or heptads. No radical has a highervalence than eight, and the two high- est valences (seven and eight) are comparatively rare. 614. Radicals of a higher atomic value than that of hydro- gen, or radicals having more than one free bond, are called polyvalent radicals. Thus all atoms and compound radicals except monads are polyvalent. In comparing the structures of compound radicals and of binary and ternary molecules with each other, this term is convenient. Radicals having the same valence may be called equiv- alent. Thus potassium and hydrogen are equivalent atoms, both being univalent: zinc and oxygen are equivalent, for both are dyads. 615. Bonds. — The valence units or affinities of atoms are sometimes, for convenience, called bonds. Thus, a monad or univalent atom has one bond; a dyad or bivalent atom has two bonds; a triad or trivalent atom has three bonds; a tetrad or quadrivalent atom has four bonds; a pentad or quinquivalent atom has five bonds; a hexad or sexivalent atom has six bonds; and a heptad or septivalent atom has seven bonds. Any atom which saturates or replaces j Has the following- i - ,. . number of bonds, j i:> cauea a And is 1 atom of hydrogen or chlorine. 2 atoms 1 bond. Monad, Univalent. 2 bonds. Dyad, Bivalent. 3 Triad, Trivalent. 4 " Tetrad, Quadrivalent. 5 " Pentad, Quinquivalent. 6 " Hexad. Sexivalent. • 7 M Heptad, Septivalent. 616. We might liken the atoms to coins, each having a definite value corre- sponding with the combining power. Monads may be likened to one-cent coins, dyads to two-cent coins, triads to three-cent coins, tetrads to four-cent coins, etc. As a two-cent coin is worth two one-cent coins, so a dyad atom is equal to two monad atoms; as it takes three one-cent pieces, or one two-cent and one one-cent piece to equal one three-cent piece, so does it take three 154 CHEMISTRY. monad atoms, or one dyad and one monad to equal one triad; and as three two cent pieces have the same value as two three-cent pieces, so are two triad atoms equal to three dyad atoms, etc. • 617. Variable Valence. — But the valence of elements is not always constant. Indeed very few of the elements seem to have a constant valence. Hydrogen and oxygen, which are the most remarkable and important of all elements, are assumed to have a constant valence. It was shown that (579) nitrogen and manganese have each five differ- ent oxides, or compounds formed by them with oxygen. 618. Among the examples of variable valence we find: Nitrogen appears to be trivalent in forming ammonia because in that molecule 1 atom of nitrogen is united to 3 atoms of hydrogen ; while in a molecule of ammonium chloride 1 atom of nitrogen is united to 4 atoms of hydrogen, and I atom of chlorine besides, thus appearing to have in this case a total valence of 5. Phosphorus unites with 3 atoms of hydrogen to' form phosphine, and is then apparently a triad ; but when 2 atoms of phosphorus unite with 5 of oxygen the phosphorus would seem to be a pentad, for each oxygen atom has a valence of 2. Sulphur unites with two atoms of hydrogen and is then bivalent; but one atom of sulphur also unites with two atoms of oxygen and then it seems to be a tetrad ; and in the sulphuric acid molecule it appears as if it were a hexad. 619. In some notable instances it appears as if variable valence depends upon the electro-chemical polarity. Thus sulphur \s positive toward oxygen, but negative toward all other ele- ments, and you will find that negative sulphur is always a dyad, while sul- phur united to oxygen (positive sulphur) presents the higher valences of four or six. Nitrogen is negative toward hydrogen but positive toward oxygen, so that we have negative nitrogen in ammonia but positive nitrogen in nitric anhydride (569). The negative nitrogen is a triad, but nitrogen united to oxygen may apparently have a valence of either one, three, or five. In nitric acid the nitrogen seems to be a pentad. And if a molecule of ammonia be brought in contact with a molecule of hydrochloric acid, the nitrogen of the ammonia not only changes its valence from that of a triad to that of a pentad, but it also changes its electro-chemical polarity from negative to positive. Phosphorus, like the nitrogen, is negative in its union with hydrogen, and then always trivalent, but it is positive in the formation of its oxides and compound radicals with oxygen and then may have, apparently, one, three or five valence units. CHEMISTRY. *55 Chlorine is always univalent when it acts as an electro-negative radical, as in all chlorides, but the molecular formulas of its oxides and acids indicate higher valences for the positive chlorine. [In certain cases it has been observed that the valence of an element may be changed by heat.] 620. It has been found that the valence of an atom never varies by a single valence unit, but always by two units, or by a multiple of two units. Thus an atom which exhibits a valence of 1 in one of its compounds, may in other compounds show a valence of 3, or 5, or 7, but never 2, 4, or 6; and another atom exhibiting in one case a valence of 2 may in other cases show a valence of 4 or 6, but never 1, 3, 5 or 7. 621. It has been sought to explain this fact on the assump- tion that the true valence of any atom is its highest apparent valence, and that this maximum vale?ice may be diminished by the mutual saturation of pairs of its bonds (615). To illustrate this partial self-saturation of atoms we will pict- ure a series of atoms with bonds representing their respective valences: o-okV MONAD. DYAD. TRIAD. TETRAD. PENTAD. HEXAD. HEPTAD. Or, they may be represented as follows, since the direction in which the bonds are extended is, of course, immaterial, and neither of these pictures can be likenesses of actual atoms: 0-0=00= one The mutual saturation of pairs of bonds may be represented as follows: HEPTADS CHANGED TO PENTADS. HEPTADS CHANGED TO TRIADS. #CH PENTADS CHANGED TO TRIADS. (2xo= TRIADS CHANGED TO MONADS. 15^ CHEMISTRY OCTAD CHANGED TO TETRAD, AND TETRADS CHANGED TO HEXAD TO DYAD. DYADS. Thus, if this assumption be accepted, a heptad can change to a pentad by the mutual saturation of two of its bonds, or it can become a triad by the mutual saturation of two pairs of its bonds, or it may even become a monad by the mutual saturation of six of its bonds in pairs. A hexad may become a dyad by the pairing of four bonds, or a tetrad if only two of its bonds be paired off. But an artiad can never become a perissad, nor can a perissad change to an artiad. In other words, no atom can at one time present an even number of bonds and at another time an odd number. 622. In view of the variable valence of atoms it is difficult to classify the elements according to their valence, beyond a separation of the artiads from the perissads. The following table is arranged according to the maximum valences of the respective elements. The comparatively rare and unimportant elements are omitted from this table, and in all cases where the ruling valence differs from its maximum va- lence, the ruling valence of the element, or that valence which it plainly exhibits in its most important and stable compounds, is shown by Roman numerals in brackets : — Table of Atomic Values of the Elements (according to the maximum valence): Monads (univalent, or with one bond ): Hydrogen. Negative Chlorine. " Bromine. " Iodine. Dyads ( bivalent or with 2 bonds ) Oxygen. Negative Sulphur. Magnesium. Zinc. CHEMISTRY. 157 Cadmium. Mercury. Copper. Triads ( trivalent, or with 3 bonds ): Boron. Sodium ( I ). Negative Nitrogen. Silver ( I ). Negative Phosphorus. Gold. " Arsenic. Tetrads ( quadrivalent, or with 4 bonds ): Carbon. Calcium (II). Silicon. Strontium ( II). Tin. Barium (II). Aluminum. Platinum. Lead (II). Pentads (quinquivalent, or with 5 bonds): Positive Nitrogen (also I and III). Phosphorus (III). " Arsenic ( III ). Potassium ( I). " Antimony ( III ). Bismuth (III). Hexads (sexivalent, or with 6 bonds): Positive Sulphur (also IV). Chromium ( II ). Manganese ( II ). Iron (Hand IV). 623. The complexity of molecules depends mainly upon the relative valence of their component atoms. This will be easily understood when we remember that all the valence units in the molecule must be mutually tied, combined, satisfied, or saturated. 624. Valence has no relation to the energy of chemism called chemical affinity. Chlorine, though a monad, has a powerful chemical affinity, whereas carbon which is quadrivalent is entirely inactive at ordinary temperatures. The trivalent element, phosphorus, on the other hand, is more energetic in its f ; CHEMISTRY. chemical combining power than either quadrivalent carbon, trivalent nitrogen, bivalent snlphnr, or univalent hydrogen (521). 625. A" ::~c:ur.i nAziA live ir r.vir:i: e viAn:e: a-. r; varnhA alence see-. 5 ::> occur only in what is cailed inorganic chemistry. 626 As A-z: 15 :he ziuses ::' va: :ze rerr.i r. unk-.r^r. :he . /. " • 5 : :h e ~ :i. : : ~ : : : : a : . : r. : r. us: : : r. : r.ue : : ir pear Ass 5 : ~ 7. . e : he r. : h e y ::::::;■ ire :r. r e 1 . : : y A. :h e rr. e ar. : : ~ e — e ~ 1 5 : re~ e ~A er .hi: :h e ::' many eArr.enzs :s varAzA :ha: :he mix mam vi'.er.ie ::' in a:_rr. may r.:t :e ;s zzmmzr. vaAnze r.zr ::s vaAnze in i:s m:s: imyzr.an:. :r i:s 21:5: B_: :r. ah uses ~here ~ne kn:~ :he raAzaA enzerinz: .:.:: 1 mzAzaA. arA aA: :he:r resyezzive vaAnzes ~e :ir. rea z.'.y : : r.s ::_ :: ::.: : mzAzznar ArmiAs I en A. :ises -here eAmer.zal raAzaA ire zznzemei i: is rraz::- zame :: zase :he mz AzAar zzrmiAs z: rr. :s: :: :ie rr.r :r:ir.: zzmyzurAs i::r. vaAnze and :: Aarn :; — rAe ArmiAs i:::r: nz. CHAPTER XXX. ::-::m::a: :;::a:::v 627. Chemical Notation is the system of representing at: — s an d :u Ae tales :y means ::' syrr.btls and fhrnzuAas. Atoms are represented by symbols; molecules by formulas. 628. Symbols -re ^zbreviations or signs consisting of let- ters. In many cases the symt :'. consists of but one letter, and in all such cases that letter is the initial of the Latinic name of the element. In cases where the Latinic names of two or more elements begin with the same letter, an additional letter from that name is added to make the necessary distinction. The additional letter thus used may be the second letter in the name, or some other letter. The svmbols, therefore are abbreviations of the Latinic names :: the elements, ar.d tensist ::' but :ne :r r.v; letters. In CHEMISTRY T 59 symbols consisting of two letters only the first is a capital letter. No two atoms are represented by the same symbol. Thus Boron is represented by B, Carbon by C, Hydrogen by H, Nitrogen by N, Oxygen by O, Potassium by K (the Latinic name of it is Kalium), etc. As B is used for Boron, Ba is the symbol for Barium, Bifor Bismuth, and Br for Bromine. C being the symbol for Carbon, Ca is used for Calcium, CI for Chlorine, and Cu (from Cuprum) for Copper. Having given the sym- bol N to Nitrogen, it was necessary to make the symbol for Nickel Ni, and for Sodium Na (from Natrium). 629. To represent one atom the symbol is sufficient alone. To represent an elemental molecule the symbol is accompanied by a small Arabic numeral to the right of the symbol, the num- ber expressing the number of atoms contained in the molecule, thus:— H 2 , K 2 , 2 , P 4 ,Cl 2 ,etc. 630. Formulas are combinations of symbols with numer- als to express the kinds and numbers of atoms entering into the molecules of matter. The formulas for elemental molecules, as shown in the pre- ceding paragraph, are simple because elemental molecules each contain but one kind of atoms. The formulas for compound molecules are constructed out of at least as many symbols as there are different kinds of atoms in the molecule which is to be represented, and after each sym- bol is placed the numeral expressing the numbers of atoms if more than one. The positive radical is always placed before the negative radical. As the molecule of potassium iodide contains one atom of the positive potassium and one of the negative "iodine, its molecular formula must be written KI; but the molecule of water is composed of two atoms of hydrogen and one atom of oxygen, and its formula must, therefore, be H 2 0; a mole- cule of hydrochloric acid is HC1, for it contains one atom of each of hydrogen and chlorine, and the molecular formula for hard soap (sodium oleate) is NaCi b H 33 02, because it contains one atom of sodium, eighteen atoms of car- bon, thirty-three atoms of hydrogen and two atoms of oxygen. 631. Single molecules are represented by the respective l6o CHEMISTRY. molecular formulas. Thus HC1 represents not only hydrochlo- ric acid, but also one single molecule of hydrochloric acid. When two or more molecules are to be written, a large Arabic numeral is placed in front (or to the left) of the molecule. Thus three molecules of hydrochloric acid must be written 3HG; two molecules of water must be written 2H0O; and 5KI stands for five molecules of potassium iodide; 4NH3 represents four molecules of ammonia, and 2NaC 1? H 33 2 means two molecules of sodium oleate. 632. When a group of atoms or a compound radical is to be multiplied, the symbols of the atoms or the formula of the radical must be enclosed in brackets and the numeral placed outside below and to the right. Thus, Ca(OH) 2 represents calcium hydrate, which contains one atom of calcium, two atoms of oxygen and two atoms of hydrogen; but as each hydrogen atom is united directly to one of the oxygen atoms and the com- pound thus contains two groups of the radical HO, and as this radical is united to the calcium atom by means of bonds from the oxygen, the formula is correctly written Ca(OH) 2 . The formula Pb(N0 3 ) 2 represents lead nitrate, which contains the group X0 3 twice. [Entire molecules are occasionally multiplied in the same manner — that is, by enclosing the molecular formula in brackets and placing the multipli- cator or numeral outside, below, to the right.] 633. A large numeral placed in front of any formula applies to all that follows it up to the first period; except that if that numeral is placed directly in front of brackets enclosing a form- ula the number multiplies all that is contained within those brackets. In 2K2CO3 the first figure 2 applies to all that follows it as a whole. In 2K2CO3. 3H2O the first figure 2 applies to K 2 C0 3 , and to nothing more, and the large figure 3 applies to the formula H 2 0. But in 3 (2K 2 C0 3 . 3H2O), and in (2K2CCV 3H 2 0) 3 the figure 3 outside the brackets applies to all within. In 4MgC0 3 . Mg (OH) 2 .5HoO the figure 4 applies only to MgC0 3 ; the inferior figure 2 in Mg (OH) 2 applies only to the group OH, and the figure 5 applies to H 2 0. In 3Pb(C 2 H 3 2 )2 the figure 3 in front applies to the entire formula which follows, viz., to Pb(C 2 H 3 2 ) 2 . In 6(NaC 2 H 3 2 3H2O) the figure 6 applies to all that is contained within the brackets. In 2(Fe 2 (C 6 H 5 0:)2. 6H 2 0) the large figure 2 in front applies to all that CHEMISTRY. l6l follows, while the inferior figure 2 in (C^HoOt)? applies only to the group CeHjOv, and the large figure 6 only to H ; 0. In Fe 4 (P 2 07) 3 . 4(Na 3 C 6 H 5 7 ). SH ; 0. we see that there are four atoms of iron, 3 groups of the radical PoO-, then 4 times Xa 3 C 6 Hs07, and 8 molecules of water. Thus it will be seen that in representing the formulas of some complex molecules it is necessary to use both large and inferior numerals, more than one pair of brackets, and brackets within brackets. 634. The valence of elements is indicated by Roman numerals at the top and a little to the right of the symbol, thus: — Hi means univalent hydro- gen; O'i means bivalent oxygen; N"» means trivalent nitrogen; Xv, quinquiv- alent nitrogen; C' v means quadrivalent carbon; S"» bivalent sulphur; S iv » quadrivalent sulphur; S vi i sexivalent sulphur; Ta v . quinquivalent tantalum; and \Y V >, sexivalent tungsten. 635. Chemical Equations. — Chemical decompositions and reactions are conveniently and clearly represented by the num- bers and formulas of the molecules which are decomposed in the reaction and the numbers and formulas of the molecules result- ing by it. This is done in the form of an equation. The molecules which take part in the change are placed on the left of the sign =, and the molecules of the product or products on the right. Thus: Fe 2 -}-2l 2 =2FeI 2 ; 2 Na 2 HP0 4 — H 2 0=Na 4 P 2 7 ; CaCl 2 + Na 2 C0 3 =CaC0 3 4-2NaCl; and Hg 2 (NO s ) 2 . 2H 2 0=2HgO+N 2 4 +2H 2 0. 636. The number of molecules taking part in a chemical reaction varies according to the respective valences of the rad- icals concerned, or the atomic rearrangement produced. In many cases only one molecule of each reagent is required to complete the reaction; but in other cases several molecules of each may be necessary. One molecule of silver nitrate and one molecule of potassium iodide will react upon each other to form one molecule of silver iodide and one molecule of potassium nitrate, thus: — AgN0 3 +KI=AgI+KN0 3 . In the preparation of solution of chloride of antimony, one molecule of 162 CHEMISTRY. sulphide of antimony reacts with six molecules of hydrogen chloride, thus:— Sb 2 S 3 +6HCl=2SbCl 3 + 3H 2 S. In the preparation of sodium valerate the reaction involves three mole- cules amylic alcohol, two molecules potassium bichromate and eight mole- cules sulphuric acid, thus: — 3C3H ia O + 2K 2 Cr 2 O7+8H 2 SO 4 =3C 3 H l 0O 2 + 2K 2 SO 4 + 2(Cr 2 SO4)3)-r-iiH a O. 637. Both Sides must be Equal. — Both members of the chemical equation must contain the same kind and number of atoms, and the sum of the molecular weights on one side of the equality sign must be equal to the sum of the molecular weights on the other side. 638. The student must learn the use of symbols and how to write for- mulas and equations by actual practice. This can best and most safely be accomplished with the aid of a competent teacher, who will point out any errors. All that is necessary for the present is that the student shall thor- oughly memorize the symbols employed to represent the most important ele- ments, which are as follows : Element. Symbol. Element. Symbol. Hydrogen. H. Strontium. Sr. Fluorine. F. Barium. Ba. Chlorine. CI. Magnesium. Mg. Bromine. Br. Zinc. Zn. Iodine. I. Cadmium. Cd. Oxygen. O. Aluminium. Al. Sulphur. S. Cerium. Ce Carbon. C. Chromium. Cr. Silicon. Si. Manganese. Mn. Tin. Sn. Iron. Fe. Boron. B Nickel. Ni Nitrogen. N. Cobolt. Co. Phosphorus. P. Lead. Pb. Arsenic. As. Copper Cu. Antimony. Sb. Mercury. Hg. Bismuth. Bi. Gold. ' Au. Lithium. Li. Silver. Ag. Sodium. Na. Platinum. Pt. Potassium. K. Molybdenum. Mo. Calcium. Ca. Tungsten. W. The symbols of all known elements will be found on pages 112-113, and the origin of each symbol will also be found on the same pages, as the table there given includes the Latinic titles of all the elements (465) The memorization of the symbols of important elements is absolutely necessary before the student can make much progress in the study of chemistry. 639. After the student has perused the whole number of pages devoted CHEMISTRY. i6t, to chemistry in this book he should return to a study of this chapter and learn it thoroughly. Much of what is contained in this chapter is at this stage unintelligible to the student; but after reading the next few chapters he should read this again. CHAPTER XXXI. THE ELEMENTS. 640. General Review. — Of the seventy elements about four- fifths are metals, the remainder being called non-metallic elements. It is impossible, however, to draw the line absolutely between metallic and non-metallic elements, because several elements partake more or less of the characteristics of both classes, physically as well as chemically. 641. The metals are: Molybdenum, Nickel, Osmium, Palladium, Aluminum, Erbium, Antimony, Gallium, Arsenic, Germanium, Barium, Glucinum, Bismuth, Gold, Platinum, Cadmium, Indium, Potassium, Caesium, Iridium, Rhodium, Calcium, Iron, Rubidium, Cerium, Lanthanum, Ruthenium, Chromium, Lead, Samarium, Cobalt, Lithium, Scandium, Columbium, Magnesium, Silver, Copper, Manganese, Sodium, *Didymium, Mercury, Strontium, 642. The non-metallic elements are: Boron, Hydrogen, Bromine, Iodine, Carbon, Nitrogen, Chlorine, Oxygen, Fluorine, Phosphorus, * (Split into two metals.) Tantalum, Tellurium, Terbium, Thallium, Tin, Titanium, Tungsten, Uranium, Vanadium, Ytterbium, Yttrium, Zinc, Zirconium. — 57, Selenium, Silicon, Sulphur. — 13. 164 CHEMISTRY. 643. The preceding classification is wholy artificial and based upon external appearances and physical properties, espe- cially upon metallic lustre or want of it, tenacity or want of it, etc. It is true that in some instances elements which naturally fall into characteristic groups according to their chemical proper- ties and compounds are not separated; but in other instances well defined natural groups are broken by this artificial classification. 644. Sometimes arsenic antimony, bismuth, and tellurium are classed with the non-metallic elements, the three first named because they are so closely related to nitrogen and phosphorus which are unquestionably non- metallic, and tellurium because it so much resembles sulphur in its chemistry. But if these metallic substances are to be classed with the non-metallic for chemical reasons, there are other metals, as tin, molybdenum and tungsten, which might with equal propriety be classed among the non-metals. 645. State of Aggregation. — The metals, with but one exception, are solid. The exception is mercury, which is liquid under ordinary conditions, solid below — 40 C. ( — 40 F.), and vaporizes at +350 C. (662°. F.). Of the non-metallic elements boron, carbon, iodine, phos- phorus, selenium, silicon and sulphur are solids; bromine is a liquid; and chlorine, fluorine, hydrogen, nitrogen and oxygen are gases. 646. Fusibility of the Solids. — All the metals are fusi- ble, some of them at temperatures below the boiling point of water, some only at extremely high temperatures, others between these extremes. Among the solid non-metallic elements boron, carbon and silicon are infusible. 647. Volatility. — Mercury, potassium, sodium, zinc, magne- sium, cadmium and arsenic can be distilled; tellurium and anti- mony can be distilled only with a current of hydrogen. Of the non-metallic elements iodine, phosphorus, selenium, sulphur and bromine are vaporizable. 648. Crystallization. — Many of the metals are crystalliza- CHEMISTRY. 165 ble; the greater number of these form cubes or regular octo- hedrons; tellurium, arsenic and antimony crystallize in rhombo- hedrons of the hexagonal system. Bismuth, zinc, copper, lead, tin, silver and gold all crystal- lize. All the solid non-metallic elements are crystallizable. 649. Opacity is given as one of the properties by which metals may be distinguished from the non-metallic elements. But gold in thin layers placed between two plates of glass trans- mits greenish light. Of the solid non-metallic elements boron, carbon (as char- coal, coal and graphite) iodine, selenium, silicon and sulphur are opaque; while phosphorus is translucent, and carbon as dia- mond is alone transparent. 650. Lustre. — The metals possess a peculiar lustre, espe- cially when polished. Some metals have this quality in much higher degree than others. But boron, carbon (as diamond and as graphite), silicon, iodine and sulphur also possess a lustre. 651. Color. — When in compact masses the metals have usually a white color with a more or less marked tendency toward grayish or bluish; but barium, calcium and gold have a yellowish or yellow color, and copper is reddish. In this respect the non-metallic elements vary greatly among each other and from the metals. 652. Density. — The specific weights of about two-thirds of the metals exceed 5: but of the remainder several have specific weights below two. Of some of the heavy metals (674) the specific weights exceed 10, the heaviest being Platinum 21.5 and iridium 22.4. It is commonly stated that metals, as a rule, have higher specific weights than the non-metallic elements, but more than one-half of the non-metallic elements have specific weights ranging from 1.83 to 4.95. Really we can only say in this direction that the specific weights of two-thirds of the metals are higher than those of any non-metallic elements, and the specific weights of several aon-metallic elements are lower l66 CHEMISTRY. than those of any metals, while the specific weights of the greater number of the non-metallic elements are higher than those of the alkali-metals (676) and several of the alkaline earth metals (678). In fact, several elements which resemble the non-metallic elements more than they resemble metals in their chemical properties have higher specific weights than many undoubted metals which are chemically farthest removed from the non- metallic elements. 653. Metals are relatively better conductors of heat and of electricity than non-metallic elements. But the metals exhibit these properties in a high degree only when in solid, compact masses; obtained in a state of fine division by precipi- tation they are far less effective conductors of electricity and heat. 654. Tenacity, ductility and malleability are properties belonging to many of the metals, and to none of the non-metallic elements. But there are also many metals which do not possess these properties, as bismuth, antimony, arsenic, manganese, chromium, zinc, tungsten, molybdenum and vanadium. 655. Solubility. — No metal is soluble in any simple solvent. Most metals are soluble chemically in the stronger acids, and some also in strong alkalies; others only in "aqua regia." Of the non-metallic elements boron, carbon and silicon are insoluble in all simple solvents; but iodine and bromine are soluble in alcohol and in glycerin; phosphorus, selenium and sulphur in fixed oils and carbon disulphide. 656. Occurrence in Nature. — Gold, silver, mercury, copper, lead, bismuth, arsenic and antimony occur free or uncombined. The metals of the platinum group occur together in the so-called platinum ore and osmium-iridium, in a metallic state. Iron and nickel, in the free state, occur in meteors. No other metals occur uncombined. It is a]so to be observed that silver, mer- cury, copper, lead, arsenic, antimony, iron and nickel occur only in small quantities uncombined, and in much larger amounts in their native compounds. The most common forms in which heavy metals exist in nature CHEMISTRY. jCj is in chemical combinations with oxygen and sulphur, and less frequently with other non-metallic elements and compound radicals. Of the non-metallic elements carbon (as graphite and dia- mond), nitrogen, oxygen and sulphur are found uncombined. These are also found, and in much larger quantities, combined with other elements: carbon and nitrogen chiefly with non- metallic elements in organic substances; oxygen with hydrogen in water, with silicon in silica, with nearly all the metals, and with carbon and hydrogen in organic substances; while sulphur occurs mostly combined with iron, copper, lead, zinc and other . metals. Bromine, chlorine, fluorine and iodine (the " halogens ") occur combined with sodium and other metals; and the remain- der of the non-metallic elements chiefly combined with oxygen. Of all the seventy elements oxygen is the most abundant, then probably silicon, aluminum, iron, calcium, carbon and hydrogen. 657. Alloys and Amalgams.— Some of the metals com- bine with each other, sometimes in definite proportions, forming even crystallizable compounds. The most interesting compound of this kind is one consisting of two atoms of antimony and three atoms of zinc. The chemical union of metals in definite atomic proportions, and in accordance with their valence, is attended with the evolution of heat, which is strong additional evidence that the union is a true chemical re-action. But mixtures of metals prepared by fusing them together, in proportions other than such as would be in accord with the atomic weights, are commonly employed in the mechanical arts, and they are called alloys. These alloys probably contain true chemical compounds of the metals, which, in a state of fusion, are soluble in (or miscible with) each other. That this is the case is indicated by the fact that when the molten mass is rapidly cooled a homogeneous mass in obtained; while, if the cooling be slow, the less readily fusible compounds may crys- tallize out, leaving the more fusible alloy still in a liquid state, l68 CHEMISTRY. so that, when the whole has become cold, the mass is not uni- form. A most striking property of alloys is the fact that their fus- ing points are lower than those of their constituents. Thus cadmium melts at 315 C. (599 ° F.), tin at 227°.8 C. (442° F.), lead at 325 C. (617 F.), and bismuth at 264 C. (507 F.); yet an alloy (Wood's) made of 1 to 2 parts of cadmium, 2 parts of tin, 4 parts of lead, and 7 to 8 parts of bismuth melts at from 66° to 71 C. (i5o°.8 to I59°.8 F.). Arcet's alloy is made of 8 parts of bismuth, 5 parts of lead, and 3 parts of tin, and melts at 94°-5 C. (202 F.). Brass, bronze, gun metal, bell metal, German silver, type metal, pewter, britannia metal, solder, coin metal, and several other metallic substances are alloys. The alloys formed by mercury are called amalgams. 658. But the alloys, although evidently consisting of true chemical com- pounds, retain the essential metallic characteristics of the constituents in a high degree, thus differing very greatly from other chemical compounds in which the characteristic physical properties of the component elements are generally obliterated. The alloys are the only chemical compounds formed by the metals with each other. 659. The non-metallic elements, on the other hand, form with each other numerous chemical compounds of the most varied nature, and they also severally combine with the metals. When a non-metallic element combines with another non-metallic ele- ment or with a metal the compound formed is usually radically different from either of the elements entering into that com- pound. 660. We have seen that the only compounds which metals form with each other resemble in their essential physical prop- erties the metals of which they are composed (658). They are solid, hard, opaque, lustrpus, tenacious, ductile, malleable, or brittle, according to the character of their component metals in these respects, and their color also is such as would naturally result by a mere physical mixture of the constituents. 661. But when non-metallic elements enter into chemical compounds, the state of aggregation, density, consistence, color, solubility, and other physical properties of the compounds have apparently no relation to the properties of the component ele- ments (662). CHEMISTRY. j6p 662. Oxygen and hydrogen are gases; they can be compressed to the liquid state only by the aid of tremendous pressure and extreme cold; but when they combine chemically with each other the compound formed is water. Carbon can not, by any means at present known, be converted into a liquid or a gas; it is infusible and fixed. But the compounds of carbon with oxygen, hydrogen and nitrogen, are gases, liquids and solids. Iodine is a bluish-black solid of a peculiar, penetrating odor; but its compound with hydrogen is a colorless gas having a very different odor. Carbon, in its ordinary condition, is a black solid; sulphur is a yellow solid; both are inodorous. But the compound of carbon and sulphur is a col- orless, offensively odorous liquid. Mercury is a bluish-white, shining liquid metal, and oxygen, a colorless gas: but they form two different compounds with each other, both solids, one of them either orange red, brick red or orange yellow, the other, grayish black. 663. Numerous other examples might be given to illustrate the radical change of properties which follows chemical reactions in which the non-metal- lic elements are concerned. Indeed, it would seem as if these striking differences between the metals and the non metallic elements afforded reasons stronger than any others for the classification of the elements into metallic and non-metallic. Yet these striking distinctions, as far as they extend, are not lost by the more natural classification of the elements according to their chemical behavior and the character of their compounds, but are rather brought out more clearly. 664. The fact that the properties of the elements bear some simple rela- tion to their atomic weights seems to be beyond doubt. It has been formu- lated in the conclusion that "the chemical properties of the elements are a periodic function of their atomic weights." The atomic weights in many instances differ by the number, 16, representing the atomic weight of oxygen (H=i), or by a number which is nearly a multiple of 16. It has also been shown that these simple differences are to be observed between the atomic weights of elements possessing many similarities in chemical behavior. Further, it has been found that in many natural groups of elements the atomic weight of one member is frequently one-half of the sum of two other members, etc. Many chemists have tabulated the elements in various ways to bring out these periodic co-incidences, in the hope of finding a true expla- nation of them. The most complete table of this kind is that of the Russian chemist, Mendeleeff. The properties which seem to bear such a periodic rela- tion to the atomic weights include: relative electro-chemical polarity, valence, specific weights, atomic volumes, specific heat, etc. Mendeleeff 's table is as follows: 170 CHEMISTRY. «£ ^C3 > 1 •: 1 i ; Cu 5 1 ! 2 1 < o £^ Sf 1—1 & > c . 3 "^ 6 | h? 03 r- i-IvO > u £ d . 4\ \ 6*i (/) ro C/3 t^ >' >a U o Hoo £ j fc " £s CC o >■ U n 00 ^ H ^ N g. "'? P. a 5 5- *i lU >X 00 ►4 ro 03 h P5 1 - ' I/) 00 03 ro : 1 5 ^ 4 J? ; U M : ~ < 2 be • xg : j d * | & ff M £ Si ; B H | 1 CHEMISTRY. 171 CHAPTER XXXII. OXYGEN, HYDROGEN AND SULPHUR. 665. Oxygen (O; at. w. 1 6) is a colorless, odorless, taste- less gas, which constitutes over one-fifth of the weight of the air. One liter of 2 at o° C. and 760 mm barometric pressure weighs 143 Grams. Water is composed of 8 parts of oxygen and 1 part of hydro- gen, chemically united, nearly one-half of the weight of the rocks is oxygen, and a large proportion of oxygen is also contained in the earths and soils and in plants and animals. Its great abun- dance in nature is in itself sufficient evidence of its vast impor- tance. 666. Preparation. — Certain compounds containing O are easily decomposed, giving up their O when heated, and these compounds are, therefore, utilized in making the 2 . The most common materials employed for that purpose are oxide of mer- cury, HgO, and potassium chlorate, KCIO3. Both part with all of their oxygen when heated: 2HgO=2Hg+0 2 and 2K00 3 = 2KCI4-3O2. [When the potassium chlorate is mixed with about one-fourth of its weight of manganese dioxide (" black oxide of manganese") the decomposition progresses more quietly and evenly, although the manganese dioxide does not take part in the reaction.] 667. Oxygen combines with all other elements except fluor- ine alone. Oxidation is the union of oxygen with other elements, or with compound radicals (804). Chemical combina- tion with oxygen, or oxidation, is one of the most common and important of chemical reactions. When oxidation is very rapid and accompanied by the evolution of heat and light it is called fire or combustion. Substances which take up oxygen and become chemically united with it are said to be oxidized. Oxidi- zation is necessary to the existence of plants and animals. Respiration is a process of oxidation. 668. But although oxygen plays such an important role in 172 CHEMISTRY. animal and plant life, and forms compounds with all other elements but one (667), it exhibits no great chemical energy at ordinary temperatures. 669. The compounds formed by the union of positive radi- cals with oxygen are called oxides. 670. When H is ignited the product of its combustion is water, H 2 0; the product of the combustion of S is the irritating gas S0 2 ; P, when burned, forms P 2 5 , which is a white solid; Mg when ignited burns with a brilliant flame, producing " magnesia," MgO; and three pounds of the metal will, when "consumed" by the fire, leave five pounds of ashes, consisting of the oxide; carbon, as charcoal or coal, forms C0 2 when its combustion is completed in a free supply of 2 , or CO if the supply of 2 is deficient; alcohol, oil, and other organic sub- stances, when burned, produce C0 2 and H 2 0. The most intense degree of heat obtainable by combustion is produced when a mixture of H2 and 2 in proper proportions is ignited. 671. Ozone is a molecule of three oxygen atoms: ^_y o or 3 . It has a peculiar odor, which is noticed sometimes in a place where lightning has just struck, or in a room where an electrical machine is in operation. Ozone has a powerful chemical energy, causing, at ordinary temperatures, the oxida- tion of metals which can not be oxidized by ordinary oxygen, decomposing potassium iodide, and destroying vegetable colors. 672. Oxygen is the strongest electro-negative element. It is always bivalent. It is, therefore, capable of linking together the most strongly electro-positive metals with the strongest electro-negative elements, like sulphur, nitrogen, etc., to form neutral stable compounds called salts. The oxides of strongly electro-negative elements form acids (with water),- while the oxides of strongly electro-positive elements, as potassium, sodium, calcium, etc., form bases (with water). 673. Oxygen, then, is present in all hydroxyl acids (884), bases (874), and oxy-salts (900). It may, therefore, be truly termed the principal salt-former, being the only constituent in CHEMISTRY. . £73 the true salts (oxy-salts), and performing, in the formation of the salt molecule, the important function of uniting the positive to the negative radical. Oxygen is also present in several of the most important com- pound radicals, as in HO, CO, N0 2 , etc., and compound radicals containing O, but not H, are always negative. 674. Hydrogen (H; at. w. 1) is a colorless, odorless, tasteless gas. It does not exist free. Its most abundant and wonderful compound is its oxide, called water, of which it con- stitutes one-ninth by weight. It is also present in most of the organic substances, animal or vegetable. One liter of H 2 at o° C, barometer at 760 mm, weighs 0.08958 Gram (called 1 crith). It is the lightest of all gases. 675. A mixture of H 3 and O s , when ignited, explodes with great violence, except when a current of the mixed gases issues from a tube through a small orifice, as in the oxy-hydrogen burner. The product is water. But water is decomposed by electrolytic action into its two component elements. 676. Preparation. — H 2 is produced by the action of zinc upon sulphuric acid or hydrochloric acid : Zn-f-H 2 SO±= Zn S0 4 +H 2 and Zn + 2HCl=ZnCl 2 +H 2 . Hydrogen is also formed together with CO by the decompo- sition of water resulting when steam is passed over coal heated to an intense temperature : 2H 2 0+C 2 =2CO + 2H 2 . This mixture of CO and H 2 is called fuel gas and water gas. 677. H 2 is, at a high temperature, a powerful reducing agent ; that is, it has a strong affinity for oxygen, and, there- fore, removes O from oxides and other molecules. 678. Water may be regarded either as the oxide of hydro- gen, H a O, or as hydrogen hydrate, HOH. It is colorless, odorless, tasteless and entirely neutral. At the ordinary tem- peratures it is liquid ; its boiling point is ioo° C. (212° F.), and its freezing point o° C. (32° F.). Its vapor is called steam, and congealed water is called ice. Its maximum density is attained 174 CHEMISTRY. at 4° C. (39'. 2 F.). Its vapor density is 9 ; Sp. w. at 4 C. = 1; mol. w. iS. The wonderful oxide of hydrogen — water — does not form any salt ; but it forms acids with the acid-forming oxides, and bases with the base-forming oxides. Water is the most important of all solvents. 679. Natural water — that contained in the ocean, lakes, rivers, springs, wells and clouds — is not pure. Sea wafer contains much salts. Spring water is called hard water because it generally contains calcium acid carbonate, and produces insoluble compounds with soap in washing. Well water is frequently contaminated with organic sub- stances, which are the products of decomposing animal or vege- table matter. Lake water and river water are often comparatively pure and soft, or nearly free from calcium compounds and other sub- stances. Rai?i water, collected after the air has been purified by the first part of the shower, and in such a manner that the water has not come in contact with roofs or other dusty or soiled objects, is the cleanest natural water obtainable. 680. Distilled water, carefully made, is the only perfectly pure water. Natural water contains both volatile and fixed im- purities. When it is distilled the volatile constituents accompany the first portion of the water vapor ; the first portion of the dis- tillate is, therefore, rejected. The distillation is discontinued before all of the water has been vaporized, because there may be fixed organic substances present which might be decomposed by the heat when the water remaining in the still, flask, or retort, is but a small quantity. Distilled water must be used for all chemical and pharma- ceutical purposes where calcium compounds, chlorides, sul- phates, carbon dioxide, ammonia, and other impurities common to natural water are objectionable. 681. Peroxide of hydrogen is H 2 2 , or H— O— O — H, or CHEMISTRY. 175 HO united to OH. It is a colorless syrupy liquid, which acts as a powerful bleaching and oxidizing agent, because it is easily decomposed, giving up one-half of its oxygen, and thus becom- ing reduced to water. A solution of peroxide of hydrogen is used in medicine, its value being dependent upon the oxygen which is being constantly liberated in it by the decomposition of the peroxide of hydrogen. 682. Hydrogen does not under ordinary conditions exhibit any marked affinity for other elements, except for chlorine and bromine ; but at high temperatures it has great affinity for oxygen and is, therefore, often employed as a reducing agent. 683. Hydrogen is always univalent (612). In its chemical behavior it is radically different from oxygen. It stands in the middle of the electro-chemical series (572) separating the relatively negative from the relatively positive elements. It generally acts as an electro-positive radical, but in many mole- cules containing hydrogen all or part of that hydrogen may be replaced by oxygen, chlorine, and other negative radicals. The hydrogen atom is, therefore, a frequently occurring radical. Thus in HC1 it is positive, in KOH it is regarded as negative, and in HOH as both. It shares with oxygen the dis- tinction of forming many compound radicals, especially with quadrivalent and trivalent elements ; but there is this notable difference that the compound radicals containing oxygen are generally acid radicals while those containing hydrogen are basic. 684. Although it maybe said that hydrogen occupies the neutral ground between the univalent radicals, chlorine at one extreme (strongly negative) and potassium at the other end (strongly positive), yet it has been recognized that hydrogen stands much closer to the metals than to chlorine. It has, indeed, been called the gaseous metal. An alloy of hydrogen with palladium has been made, and a medal consisting of that alloy, containing nine hun- dred volumes of hydrogen, was once produced. Later hydrogen was com- pressed by Pictet (at the close of 1877) into a steel-blue liquid; a portion of this liquid solidified, being deprived of its latent heat by the vaporization of another portion, and the solid pieces of hydrogen, striking the ground as they fell, produced a shrill metallic sound. 176 CHEMISTRY. 685. Hydrogen is contained in all acids as positive hydro- gen, and may be displaced from its position in the acid molecule by any other positive radical. It is contained in all bases as relatively negative hydrogen, and may be displaced from the molecule of a base by any other negative radical. In this respect then it acts wholly differently from oxygen, for the oxy- gen of an acid or a base is not thus displaced. Thus the hydro- gen in acids and bases is a relatively weak radical. 686. With the halogens (696) hydrogen forms binary com- pounds called hydrogen acids, which have the strongly marked corrosive and sour properties of true acids (hydroxyl acids), and which form with the bases other binary compounds resembling the salts and called haloids. Hydrogen is displaced from its position in the molecule of hydrogen-acids by other positive radicals, for the hydrogen in hydrogen-acids as well as in hydroxyl acids is positive hydrogen. 687. With nitrogen hydrogen forms a strongly alkaline body called ammonia — the very opposite of acids in its properties; while oxygen forms with nitrogen several oxides, one of which produces one of our strongest acids — nitric acid — when it reacts with water. 688. Hydrogen and oxygen are, together with carbon and nitrogen, the most important elements in organic chemistry. But they play entirely dissimilar r61es. With carbon hydrogen forms many compounds which are even more neutral, or chemically indifferent, toward other sub- stances than the oxide of hydrogen. 689. Among the compound radicals formed by hydrogen are HO, NH„ NH 2 , NH, HS, CH 3 , C 2 H 5 , CH 2 , CH^ C 3 H 5 , and numerous others. All compound radicals containing hydrogen but not oxygen exhibit electro-positive polarity. 690. Sulphur (S ; at. w. 32.) is under ordinary condi- tions a yellow solid, odorless and tasteless, insoluble in water and in alcohol, but soluble in fixed and volatile oils. Melts at 115 C; boils at 448 C. CHEMISTRY. 177 It occurs free as well as combined, its most important com- pounds being the sulphides (854) and sulphates (907). The sources of the sulphur of commerce are the native sul- phur and iron pyrites. Sulphur occurs in two forms — hard and soft. The soft plastic sulphur is obtained by heating the common sulphur at 200. ° to 250. C. In commerce we find roll sulphur (" brimstone"), sublimed sulphur (" flowers of sulphur "), washed sulphur (U. S. P.), and precipitated sulphur. 691. Like oxygen, sulphur is an artiad (611). The atomic weight of S is precisely twice that of O. At ordinary temperatures sulphur exhibits no marked chem- ical energy ; but at high temperatures it has a strong affinity for the metals, oxygen, and some other elements. The compounds formed by positive radicals with S. are called sulphides (854). 692. Many of the compounds of sulphur are analogous to the compounds of oxygen. Thus the acid-forming oxides are to some extent paralleled by analogous sulphides, the base- forming. oxides are also represented by corresponding basic sul- phides, and there are sulphur salts which resemble the oxy- salts in structure, the only difference being that one series con- tains atoms of sulphur where the other series contains the same number of atoms of oxygen in the same relative position. The following oxygen compounds and sulphur compounds will suffice to show their analogy : Carbon Dioxide CO, cs 2 Carbon Disulphide Hydrogen Oxide H g O HoS Hydrogen Sulphide Ferrous Oxide FeO FeS Ferrous Sulphide Calcium Oxide CaO CaS Calcium Sulphide Ferric Oxide Fe 2 3 Fe 8 S 8 Ferric Sulphide Arsenous Oxide AsoO s ASoSg Arsenous Sulphide Arsenic Oxide As 5 As 2 S 5 Arsenic Sulphide Sodium Carbonate Na„C0 3 Na 2 CS 3 Sodium Sulpho-carbonate In all these compounds, in which sulphur occupies a position analogous to that of the electro-negative oxygen, the sulphur acts as a dyad. But in all 178 CHEMISTRY. molecules and radicals in which sulphur is united to oxygen, the sulphur thus playing the role of a positive element, it is apparently a tetrad or a hexad. ■Selenium and Tellurium resemble sulphur in their chemistry. 693. The oxides of sulphur are sulphurous anhydride, S0 2 , and sulphuric anhydride, S0 3 . Sulphurous anhydride, or sulphur dioxide, is formed when sulphur is burned in air, and is the " sulphurous vapor " observed in igniting sulphur matches, and which is so irritating to the air passages. Dissolved in water it forms sulphurous acid. It has strong bleaching properties. The sulphuric oxide, or sulphuric anhydride, or sulphur trioxide, is not so readily prepared ; but the acid it forms when brought in contact with water is familiar to us under the name of sulphuric acid, which is chemically the strongest of all acids and terribly corrosive. 694. Sulphuric acid is prepared by first burning sulphur (or pyrites') to form S0 2 , which is conducted into a lead cham- ber, where it comes in contact with N 2 0± (generated separately), water vapor and air. The S0 2 is oxidized at the expense of the N 2 4 to S0 3 : 2 S 2 + N 2 4 =2 SO3+ N 2 2 . The N 2 2 then takes up O from the air, forming N 2 4 again : N 2 2 +0 2 =N 2 4 . The S0 3 forms sulphuric acid with the water : S0 3 +H 2 0=H 2 S0 4 . Sulphuric acid is one of the most useful of all the strong acids, because it decomposes -numerous other compounds on account of the strongly electro-negative polarity of the sul- phate radical. Other acids are thus prepared by decomposing their salts by sulphuric acid. The official sulphuric acid is nearly absolute H 2 S0 4 , being required to contain at least 96 per cent. It is an oily, colorless liquid of 1.840 sp. w. (water = 1). 695. With hydrogen, S forms the colorless gas H 2 S, known as hydrogen sulphide, or sulphuretted hydrogen, or hydrosul- CHEMISTRY. 1 79 phuric acid, or sulphydric acid. This gas has the odor of rot- ten eggs, and is poisonous when inhaled. It is soluble in water. Its principal use is as a chemical reagent for the pre- cipitation of the heavy metals from the solutions of their salts, which is possible because these sulphides are insoluble in water. It is prepared from ferrous sulphide by the action of sul- phuric acid : FeS + H 2 S0 4 =FeSO i + H 8 S. CHAPTER XXXIII. THE HALOGENS. 696. The Halogens are a characteristic group of the four elements: fluorine, chlorine, bromine, and iodine. The chem- ical energy of fluorine is so intense that it has not been possible to study its properties in the free state. Chlorine is a gas, and is endowed with very energetic chemism. Bromine is a liquid and also energetic. Iodine is a solid and has strong chemical energy, too, although relatively weaker than that of the other halogens. They form, respectively, chlorides, bromides, and iodides with the metals. But in cases where one metal forms two different series of haloids, the most stable chlorides, relatively, are the higher (or-" ic ") chlorides, while the most stable iodides are the lower (or-" ous ") iodides, and the bromides do not exhibit any marked difference as between the higher and lower. 697. The term "halogen" means salt-former. These elements are so called because they form with metals and positive compound radicals a class of compounds in many respects resembling the salts produced by the union of oxyacids with bases. They constitute a class of salt-formers very different from oxygen and sulphur. This is in some measure accounted for by the fact, that, while oxygen and sulphur are dyads, the halogens are monads. But when the dyad salt-formers are placed beside the monad salt- formers, with the atomic weights appended, the exhibit becomes intensely interesting. Here they are: l8o CHEMISTRY. Dyad Salt-Formers. Atomic Weight. Oxygen j6 Sulphur 32 Selenium 79 Tellurium I25 Monad Salt-Formers. Atomic Weight. 19 Fluorine 35.4 Chlorine 80 Bromine 127 Iodine 698. Oxygen, we -have said, is the strongest electronegative element; we may add now that fluorine is the strongest electro-negative monad. No compound of oxygen and fluorine is known. As to the remaining three members of each group, it should be observed that the atomic weights of the middle members, selenium on one side and bromine on the other, are very nearly half of the sums of the other two, a coincidence which recurs in other groups of elements. It should also be remembered that these elements stand in their groups in exactly the same order as in the electro chemical series. 699. Chlorine, and its fellow halogens, do not exhibit a strong affinity for oxygen, notwithstanding their energetic action upon metals and hydrogen compounds. This is significant. To induce chlorine to combine with oxygen it is necessary to strengthen the attraction between these elements by the presence of a strong base — or, in other words, to take advantage of the pre- disposing affinity (97) of that base for the united chlorine and oxygen. It is also to be observed that negative chlorine — the salt former — is always univa- lent, but the positive chlorine which enters into chemical union with oxygen is apparently \ as a rule, polyvalent. 700. Chlorine. — (CI; at. w. 35.4) is a yellowish green gas of suffocating odor, soluble in water to the extent of 0.6 per cent, at about io°C. At 15° C. and under the pressure of four atmos- pheres it can be rendered liquid. Chlorine does not occur free, but it exists abundantly in the combined state in the chlorides of potassium and sodium. Chlorine gas is poisonous when inhaled. One liter of chlorine weighs 3.17 Grams. 701. Preparation. — It is best prepared by the mutual decomposition of hydrochloric acid and manganese dioxide (black oxide of manganese) : Mn0 2 +4HCl=Cl 2 +MnCl 2 + 2 H 2 0. 702. Chlorine forms four different oxides, namely: Cl 2 0=hypochlorous oxide or anhydride; . Cl 2 3 =chlorous oxide or anhydride; Cl 2 5 =chloric oxide or anhydride; and Cl 2 7 =perchloric oxide or anhydride. CHEMISTRY l8l These oxides form with water, respectively, hypochlorous, chlorous, chloric and perchloric acid. These acids are unstable. 703. With hydrogen CI forms a gas called hydrochloric acid, or hydrogen chloride, the solution of which is one of the ' most important of the strong acids. This acid is prepared by decomposing sodium chloride (common salt) with sulphuric acid: NaCl+H 2 S0 4 =NaHS0 4 +HCl. Impure commercial hydrochloric acid is commonly called "muriatic acid." The hydrochloric acid of the Pharmacopoeia is a water solu- tion containing 31.9 per cent, of HC1. Other chlorides are referred to elsewhere (860). 704. The affinity of chlorine for hydrogen is remarkable. It is capable of removing hydrogen atoms from organic molecules. Each molecule of chlorine consists of two atoms; one of these atoms unites with- the atom of hydrogen while the other chlorine atom usurps the former position of that hydrogen atom in the organic compound. In numerous cases the chlorine seems, indeed, to remove the hydrogen even from its combinations with oxygen, after which the oxygen, in its nascent state, vigorously attacks other substances present. ''Bleaching powder," or "chlorinated lime" (generally misnamed "chloride of lime") contains as its only valuable constituent the unstable salt calcium hypochlorite, and the "solution of chlorinated soda" (or " Labarraque's solution ") contains sodium hypochlorite. These preparations are easily decomposed, yielding free chlorine, and their value depends upon the amount of Cl 2 they yield. 705. Bromine (Br ; at. w. 79.85) is a dark, reddish-brown, heavy, volatile liquid, having an extremely irritating odor. When inhaled it is poisonous, and its vapor attacks the eyes and air passages dangerously. It must, therefore, be kept and handled with great care, and is usually put up in glass stoppered bottles imbedded in clay enclosed in a tin box. It is insoluble in water, but soluble in alcohol, ether, chloroform and carbon disulphide, and freely soluble in solutions of iodides and bromides. It occurs in the bromides of salt springs. 1 82 CHEMISTRY. 706. Preparation. — Bromide of potassium, sodium, or mag- nesium may be used as the material for the production of Br 2 , the salt being decomposed by passing the stronger electro- negative element chlorine into a water solution of the bromide : 2KBr+Cl 2 =Br 2 + 2 KCl. 707- A solution of hydrogen bromide, containing 10 per cent, of the HBr, is official under the name of hydrobromic acid. It is a strong acid, and may be made by decomposing potassium bromide with sulphuric acid, a mixture of these two substances being subjected distillation: KBr+H 2 S0 4 =KHS0 4 +HBr. The bromides are referred to elsewhere (866). 708. Iodine (I ; at. w. 126.5) i s a crystalline, lustrous, blackish, brittle solid, having a peculiar penetrating odor. It is practically insoluble in water, but readily soluble in a solution of potassium iodide ; it is also soluble to the extent of nearly 10 per cent, in alcohol, and less freely in fixed oils and in glycerin. Ether, chloroform and carbon disulphide dissolve I 2 rather freely. It liquefies at 113 C, and boils at 200 C; but violet vapors of iodine are produced when the I 2 is heated at much lower temperatures. Iodine occurs in the iodides of salt springs and sea water. It is prepared out of the ashes of sea-weeds which contain iodides. 709. Hydrogen iodide, or hydriodic acid, is so unstable that its water solution can not be preserved from decomposition ; but the addition of a large quantity of sugar retards that decompo- sition and hence there is an official " syrup of hydriodic acid." CHAPTER XXXIV. THE NITROGEN GROUP AND BORON. 710. Nitrogen (N; at. w. 14) is a colorless, odorless, taste- less gas, which constitutes four-fifths of the weight of the air. By extreme cold and pressure it can be rendered liquid. It is neither combustible nor a supporter of combustion. CHEMISTRY. 183 Combined with other elements nitrogen is contained in albuminous substances, alkaloids, and certain other organic substances. One liter of nitrogen weighs 1.25 Grams. 711. The oxides of N are five: N 2 = nitrogen monoxide. N 2 2 = " dioxide. N 2 3 = " trioxide. N 2 4 = " tetroxide. N 2 5 = " pentoxide. The trioxide and tetroxide are liquids; the others, gases. The trioxide is blue; the tetroxide, red; the others, colorless. N 2 is often called "nitrous oxide gas," or " laughing gas/' and is used as an anaesthetic by dentists. It is prepared by heat- ing dry ammonium nitrate: NH 4 N0 3 =2H 2 0+N 2 0. 712. When nitric acid acts upon metals the acid-is usually decomposed, giving of N 2 2 ; this takes up more oxygen from the air, forming red vapors of N 2 4 . 713. Nitrogen exhibits chemical properties wholly different from those of the dyad salt-formers, the monad salt-formers, and hydrogen. The fact that nitrogen is trivalent must, of itself, distinguish its chemistry from that of either oxygen, sulphur, hydrogen, or chlorine. Nitrogen is even more indifferent in its chemical combining energy than oxygen, sulphur, and hydrogen. It does not unite directly with other elements even at high temperatures. To compel the nitrogen atoms to separate from each other and unite with other elements unusual means are necessary; the chemical affinity must be re-inforced by such favorable condi- tions as the status nascens (542), predisposing affinity (548), etc. And the compounds of nitrogen, when formed, are generally unstable, decomposing readily, and sometimes with explosive violence. Heat is often sufficient to cause their decomposition. Hence, nitrates are effective oxidizing agents, and our most powerful explosives are nitrogen compounds. The nitrogenous substances in animal matter decompose rapidly. It is clearly 184 CHEMISTRY. these very properties of nitrogen which render nitrogenous matters suitable materials. for the construction of certain animal tissues, nitrogen acting largely as a carrier of other elements and radicals. [A remarkable exception to the generally unstable character of nitrogen compounds is the peculiar compound formed of boron and nitrogen, BN.] 714. The polyvalence and indifferent chemical energy of nitrogen are its ruling characteristics. By reason of these characteristics it forms, both with oxygen and with hydrogen, powerful compound radicals, in the formation of which the nitro- gen must be regarded as a passive agent. In forming compound radicals with oxygen the nitrogen is electro-positive, with hydro- gen electro-negative. The strongest compound radicals are formed by quinquivalent nitrogen, as might be expected. Ammonium, NH 4 , and nitryl, N0 2 , are examples. But even trivalent nitrogen forms strong radicals, as, for instance, cyanogen CN. 715. The compounds formed by nitrogen with other non- metallic elements are singularly interesting. 716. It does not unite directly with any metal. We have seen that with oxygen it forms no less than five different oxides; but the radical N0 2 which combines with itself to form N 2 4 , and with OH to form nitric acid, and which enters into numerous organic molecules possessing striking properties, is the most remarkable oxide. 717. With hydrogen it forms the extraordinary substance which is so familiar to us under the name of ammonia. In this compound the nitrogen is the electro-negative radical, as we have stated. Ammonia unites directly with the acids, forming ammonium salts, the valence of the nitrogen rising at the same time from 3 to 5. A saturated compound of hydrogen with quinquivalent nitrogen (NH 5 ) does not exist. But NH 4 , NH 2 and NH exist as powerful radicals. Ammonia should be written H 3 N instead of NH 3 , the hydrogen being the positive radical of the molecule. It is not nitrogen hydride, but hydrogen nitride. The alkaloids, which in small quantities are such valuable medicines and in larger quantities frequently so deadly in their effects upon plants and animals, are derivatives (843) of ammonia, retaining the nitrogen. # CHEMISTRY. ^5 718. With sulphur nitrogen forms no stable compound, but only a violently explosive substance (N 2 S 2 ). With the halogens, also, nitrogen produces only extremely unstable molecules. 719. With carbon nitrogen forms a very remarkable com- pound radical called cyanogen, which is capable of combining with itself as well as with other radicals. In its chemical rela- tions this compound radical conducts itself like the halogens, forming cyanides with the metals and other positive radicals. Cynanogen is extremely poisonous, the acid it forms with hydro- gen (HCN), called hydrocyanic acid (formerly called prussic acid), is also a terrible poison, and so are several of the other cyanides. 720. Ammonia is prepared by double decomposition between calcium oxide ("quick-lime") and ammonium chloride: 2NH 4 Cl+CaO=CaCl 2 + H 2 0-f 2 NH 3 . NH 3 is a colorless gas having an extremely pungent odor, highly caustic and poisonous when inhaled, and affecting the eyes and air passages so strongly that solutions of ammonia (called " water of ammonia") must be handled with caution. One liter of the gas weighs 0.762 Grams. The Pharmacopoeia contains one solution of ammonia containing 28 per cent, of NH 3 , and another containing 10 per cent. When N 1 ^ is dissolved in water, the solution may be properly regarded as containing ammonium hydrate: NH 3 + H 2 0=NH 4 OH. Ammonia water is largely employed in pharmaceutical chemistry as a convenient and effective alkali hydrate (874) for the precipitation of metallic hydrates, the neutralization of acids, etc. 721. Nitric Acid is prepared from potassium or sodium nitrate by the action of sulphuric acid: NaN0 3 -+-H 2 S0 4 = HN0 3 + NaHS0 4 . It is a highly corrosive acid and extremely poisonous because of its destructive chemical action. The official nitric acid is a solution containing 69.4 per cent, of HNO s and having the sp. w. 1.42 (water=i.). This acid is used to dissolve metals (890) and as an oxidizing agent. 1 86 CHEMISTRY 722. Phosphorus and other polyvalent perissads.— Nitro- gen, phosphorus, vanadium, 'arsenic, antimony and bismuth are generally placed together in one group, called the nitrogen group, because these elements all exhibit the same valence and many parallel compounds. More than this, it is found that the members of this group disclose the same mutual relationship in their respective atomic weights as the members of the group of dyad salt-formers, the group of monad salt formers, and cer- tain other natural groups of elements. 723. The nitrogen group (which is also sometimes called the "antimony group") is as follows : Elements. Atomic Weight. Nitrogen, 14. Phosphorus, 31. Vanadium, 51. Arsenic, 75. Antimony, 120. Bismuth, 209. All are preferably triads and pentads ; but the closest relationship exists between phosphorus arsenic and antimony, which from a sub group corre- sponding to the sulphur group (sulphur, selenium and tellurium) and -the chlorine group (chlorine, bromine and iodine). The atomic weight of arsenic is very nearly one-half of the sum of the atomic weights of phosphorus and antimony. 724. Phosphorus is widely and generally distributed throughout the material world, but only in small quantities. The waxy or ordinary phos- phorus has an extra-ordinary affinity for oxygen, with which it unites even at common temperatures, igniting when exposed to the air, and burning vio- lently. It also burns in chlorine and bromine. [Red or amorphous phos- phorus, however, is comparatively indifferent as to combining energy.] The acid-radicals of phosphorus are the most important; but it may also form basic compound radicals. 725. Arsenic and antimony stand in their relations to nitrogen and phos- phorus, as selenium and tellurium to oxygen and sulphur. But arsenic, anti- mony and bismuth have marked metallic properties, and bismuth has a num- ber of salts in which it acts as a positive radical, while arsenic and antimony have not. 726. The gradual changes of the members of the nitrogen group from nitrogen to bismuth are interesting. To show their similarities and divergen- cies, the following table will suffice: CHEMISTRY. N. P. As. Sb. Bi. NH 3 PH 3 AsH 3 SbH 3 NC1 3 PCI3 PCU AsCl 3 SbCl 3 SbCl 5 BiCl 3 N 2 3 p 2 o 3 As 2 3 Sb 2 S 3 Bi 2 3 N 2 5 p 2 o 5 As 2 O s Sb 2 S 5 Bi 2 5 NH 4 Br PH 4 Br HNO3 HPO3 H3PO3 H 3 Asb 3 HSb0 3 HBi0 3 H3PO4 H 3 As0 4 HsSbO* As 2 S 3 As 2 05 Sb 2 S3 Sb 2 S 5 Bi 2 S 3 187 Vanadium is a rare metal. 727. Phosphorus (P; at. w. 31) is a soft, waxy, semi- translucent, nearly colorless or slightly yellowish solid, of peculiar odor and taste. It is of crystalline structure, luminous in the dark, poisonous. It melts at 44. ° C, and boils at 290/ C. Insoluble in water and sparingly soluble in alcohol; but soluble in chloroform and carbon disulphide; in fixed oil it is.solubleto the extent of 1 per cent. It has such strong affinity for oxygen that if allowed to come in contact with air it ignites and burns fiercely, forming phos- phorus pentoxide, which is a snowy white solid and which forms phosphoric acid when brought in contact with water. Phos- phorus must, therefore, be. kept under water, and be handled with great caution. Phosphorus occurs combined with calcium through oxygen in the calcium phosphate of bones. 728. Preparation. — The normal, ordinary, or yellow phos- phorus is made from calcined bone, which is heated with charcoal in retorts, the P 4 distilling over: 3Ca(P0 3 ) 2 +5C 2 =P 4 -i- Ca 3 (P0 4 ) 2 +ioCO. 729. Red phosphorus is formed when the ordinary phos- phorus is heated to 300 C, excluded from the air, as in C0 2 . It is called amorphous phosphorus, does not oxidize in the air, is not luminous in the dark, is insoluble in carbon disulphide, is infusible and non-poisonous. 730. P forms two oxides: trioxide, P 2 3 , and pentoxide, P 2 5 . The acids of P are: 165 CHEMISTRY. Hypophosphorous acid=H 3 P0 2 . Phosphorous acid=H 3 PG 3 . Phosphoric acid=H 3 PO i . Metaphosphoric acid=HP0 3 . Pyrophosphoric acid=H 4 P 2 7 . Their salts are called hypophosphites (918), phosphites, orthophosphates (914), metaphosphates (916), and pyrophos- phates (917). 731. Phosphoric Acid. — The ordinary phosphoric acid, H 3 P0 4 , is orthophosphoric acid, and the Pharmacopoeia con- tains a 50 per cent, solution called " Phosphoric Acid," and a 10 per cent, solution called "Diluted Phosphoric Acid." It is most frequently prepared by oxidizing phosphorus by means of nitric acid. The phosphorus is placed in nitric acid of suitable strength; when the reaction is completed the prod- uct is freed from arsenic (derived from the usually impure phos- phorus), and from other impurities, and diluted to the required strength. The reaction is: P 4 +4HN0 3 + 2H 2 0==4H 3 P0 3 +2N 2 2 ; and finally 3H 3 P0 3 +2HN0 3 =3H 3 P0 4 +N 2 2 h-H 2 0. 732. Phosphine, PH 3 , or " phosphoretted hydrogen," or hydrogen phosphide, is made by heating P 4 in a solution of KOH or NaOH. It is an inflammable, poisonous gas, of a dis- agreeable garlicky odor. 733. Arsenic (As; at. w. 75) is a dark steel-gray crystal- line, heavy solid of a dull metallic lustre. It is volatile, distill- ing without first melting, the vapors having a yellowish brown color and garlicky odor. But in the solid state arsenic is odor- less and tasteless. Insoluble in all neutral solvents. It occurs mostly in combination with S. Compounds of As are white, yellow or red. They are made from the metal or its oxide. 734. Arsenic has two oxides, namely a trioxide or arsenous anhydride, As 2 3 , and a pentoxide, or arsenic anhydride, As 2 5 . The ordinary " white arsenic," which the Pharmacopoeia calls " arsenious acid," is arsenous oxide. As is well known, it is poisonous. CHEMISTRY. 1 89 735. With H arsenic forms a gaseous compound called " arseniuretted hydrogen; " it is hydrogen arsenide, or H 3 As, and is also called arsine. Hydrogen arsenide has a garlicky odor, and is very poisonous. 736. Sulphides and chlorides of arsenic also exist, and an iodide of arsenic is contained in the Pharmacopoeia. Among the official preparations of As are solutions of potassium arsen- ite, sodium arsenate and arsenous acid; the solution of sodium arsenate is made of i part of the anhydrous salt to 99 parts of water, and the others of one per cent, arsenous anhydride. 737. Antimony (Sb; at. w. 120) is a heavy, bluish -white, crystalline solid of decidedly metallic lustre. Melts at 425 C, and vaporizes at white heat. It occurs as " black sulphide of antimony," or antimonous sulphide, Sb 2 S 3 . Nitric acid does not dissolve antimony but oxidizes it, the oxide of antimony thus formed being insoluble in nitric acid. Compounds of antimony are white, black, yellow or red. They are prepared from the sulphide or the oxide. 738. The oxides of antimony correspond to those of arsenic. The pharmacopceial oxide of antimony is the antimonous oxide Sb 2 3 , which is a white powder, insoluble in water. Antimonic anhydride is Sb 2 5 . There is also an antimonate of antimonyl, SbOSb0 3 . 739. With S, antimony forms antimonous sulphide, which is black when in crystalline form, or orange red when precipi- tated ; and antimonic sulphide, Sb 2 S 5 , which is also orange red Sulphur salts of antimony exist, as, for example, the sulphanti- monate of sodium, Na 3 SbS 4 , and sulphantimonite of sodium, Na 3 SbS 3 . 740. With CI antimony forms SbCl 3 and SbCl 5 . The tri- chloride is official in some pharmacopoeias in the form of a solution ; that "solution of chloride of antimony " must neces- sarily contain a considerable quantity of hydrochloric acid, for the SbCl 3 is not soluble in water but instead decomposed by it, while it is soluble in a mixture of water and HC1. 190 CHEMISTRY. 741. Potassium-antimonyl tartrate (KSbOC^HiOg) is com- monly called tartar emetic, and its official title is " tartrate of antimony and potassium." It is the only water-soluble anti- mony preparation in the pharmacopoeias. 742. Bismuth (Bi: at. w. 208.9) is a heavy crystalline solid of reddish-white color ; melts at 267" C, and vaporizes at white heat. It occurs in nature uncombined. Nitric acid dissolves bismuth to form the normal nitrate, Bi(N0 3 ) 3 , which is soluble in a mixture of nitric acid and water, but decomposed by water alone. The compounds of bismuth are white, black, red or colorless. They are made from the metal. 743. The oxides of Bismuth are Bi. 2 3 and Bi 2 5 . Chlorides and sulphides also exist. The normal bismuth nitrate, Bi(X0 3 ) 3 being soluble in glyc- erin, is sometimes used as the material out of which other bismuth compounds are made. " Citrate of bismuth and ammonium " is the only water-soluble preparation of bismuth known to pharmacy. The so-called ''subnitrate of bismuth" and " subcarbonate of bismuth " of the Pharmacopoeia are not bismuth salts but bismuthyl salts (BiON0 3 and (BiO) 2 C0 3 ). When a solution of normal bismuth nitrate in water and nitric acid is poured into water, the salt is decomposed and bismuthyl nitrate produced. 744. Boron (B; at. w. 11) is an altogether unique element. It is, in the free state, a solid. Its most familiar compounds are borax and boric acid (formerly called " boracic acid"). Borax is sodium pyroborate, Xa 2 B 4 7 . ioH,0: boric acid is H 3 B0 3 . Although B is a trivalent element, it possesses some analo- gies to silicon. CHEMISTRY. 191 CHAPTER XXXV. THE CARBON GROUP. 745. This group embraces carbon, silicon, titanium and tin, all of which are quadrivalent. 746. Carbon (C; at. w. 12) occurs in nature in the free state as diamond, graphite and coal. It exists only as a solid, and can be neither fused nor vaporized. Diamond is the hardest substance known, and possesses unsurpassed lustre and brilliancy. It crystallizes in various forms of the Regular System. Graphite is the so-called " plumbago," or the "black lead" of lead pencils, stove polish, etc. Coal — hard and soft — consists mainly of carbon, and charcoal is also carbon; soot, lamp-black, "bone-black" and coke are also different forms of more or less impure carbon. The specific weight varies according to the form, or allotropic modication as distinctly different forms of any one element are called. Carbon is one of the most commonly occurring and abundant of the elements. It is the most important element in organic chemistry. 747. At common temperatures carbon exhibits no chemical affinity whatever for other substances. At a very high heat it readily unites with oxygen, forming two different oxides, one of which is an acid-forming oxide, C0 2 ; carbonic acid is, however, a very weak acid. But its lower oxide, CO, figures as a most important compound radical, called carbonyl, and may also be said to form carbonic acid by uniting with (HO) 3 . Carbon combines with hydrogen in numerous compounds, and forms with that element many compound radicals. Its compounds with sulphur are analogous to those it forms with oxygen. Carbon disulphide, CS 2 , is an ill-smelling liquid. It also combines with the halogens. With nitrogen it forms the important radical cyanogen which lias already been referred to (719). 192 CHEMISTRY. 748. Carbon has apparently a variable valence as indicated by its oxides CO and C0 2 . But its other compounds show- that its ruling valence is that of a tetrad. The most striking function of carbon is its passive agency in the formation of com- pound radicals. In this respect it occupies among the artiads a position analogous to that of nitrogen among the perissads. 749. Organic Chemistry is defined sometimes as " the chem- istry of the carbon compounds." It is also defined as "the chemistry of the hydrocarbons and their derivatives." If the molecular formulas of inorganic compounds be placed beside the molecular formulas of organic compounds, and the two series compared, the organic molecules seem very complex and the inorganic molecules compara- tively simple. The differences in structure are, indeed, in numerous cases so great that the student might easily draw the erroneous conclusion that organic chemistry must be governed by laws wholly different from the laws of inor- ganic chemistry. But the chemistry of the rose and ruby, the air and the bird, gold and the apple, calomel and quinine, stone and bread, must be subject to the same laws. Inorganic chemistry and organic chemistry are not merely near relatives, of whom we might know one intimately, while having barely a speaking acquaintance .vith the other ; they are not as two persons, but as the different parts of one man. 750. The apparent complexity of organic chemistry is the natural result of the high valence of carbon, the power of the carbon atoms to combine with each other, the stability of the carbon bonds, the ability of carbon to combine with other ele- ments of the most dissimilar nature, the behavior of carbon toward hydrogen and oxygen with which it forms many com- pound radicals, etc. 751. The position of carbon in the first series of elements arranged according to their atomic weights (664) is not only the central position, but the elements on both sides of it are the first members of important natural groups, thus : I II III IV III II I Li (;), Be (9), B(n), C(i2), N (14), O (16), F (19). The valence of these elements, beginning with lithium, increases regularly from one to four (C), and then decreases as regularly toward the other end of the series. 752. Carbon, being quadrivalent, has four bonds. Each of its four valence units mav be satisfied bv a different radical. CHEMISTRY. 1 93 Carbon atoms may combine with each other in three possible different ways, as follows : II II — C— C — , C=C, or — C — C — II II Thus two carbon atoms united to each other may present together either two, four or six free bonds. A greater number of carbon atoms must produce still greater variety. 753. Other polyvalent elements may, in a similar manner, though not to the same extent, be capable of forming different chains, etc. (831}, and as both nitrogen, oxygen and sulphur combine with carbon, directly and indirectly, the possible combinations would appear to be without limit. Two nitrogen atoms may give us — N=N — or =N — N=, and three nitrogen atoms =N — N — N=, or — N=N — N=, etc. But oxygen atoms combining with each other can only form simple chains with two free bonds, and sulphur atoms likewise. 754. Add to these possible combinations the further fact that not only univalent atoms, as those of hydrogen or of chlorine, may unite with the free bonds presented by the chains or clusters of carbon atoms, but that compound radicals may be united to these free bonds, and, finally, polyvalent radicals, elemental or compound, may link the carbon chain or cluster to still other radicals, as, for example, in : CHo CHo I I HC O CH \ / O \ / HC CH 8 Paraldehyde . 755. The Oxides of Carbon. — When carbon undergoes com- bustion in a limited supply of 2 or of air, the product of the reaction is CO, or carbon monoxide, or carbonous oxide. This is a colorless, odorless, tasteless gas, which burns with a blue flame to C0 2 . Carbon monoxide is poisonous when inhaled. The higher oxide is formed carbon is burned in a free sup- ply of 2 , and is easily produced by the decomposition of carbon- ates by the stronger acids, because carbonic acid, H 2 C0 3 , at once splits up into CO2 and H.,0. Carbon dioxide is also called 194 CHEMISTRY, carbonic oxide and " carbonic acid gas." It is colorless, slightly pungent, of a refreshing, faintly acidulous taste, soluble in water. At ordinary temperatures and pressure it dissolves in an equal volume of water; but with the aid of cold and strong pressure much larger quantities of C0 2 can be forced into a state of solution in water, and such a solution is called " carbonic acid water." When inhaled the C0 2 acts as a poison, and a comparative small proportion of C0 2 in the atmosphere of a room is sufficient to render it unhealthy. 756. Silicon (Si; at. w. 28.3), which is so abundant in the silicates of the earth's crust, as in quartz rock and sand, is analo- gous to carbon in the structure of its compounds. It is of the greatest importance in its geological relations. Glass is composed of silicates of sodium, potassium, calcium and lead; glass containing the silicates of K and Ca is hard and not easily fused, while flint glass made of the silicates of K and Pb is more readily fusible and brilliant, and soft glass made of the silicates of Na and Ca fuses very readily. 757. Tin (Sn; at. w. 119) is also industrially important, although not very abundant. Notwithstanding its decidedly metallic physical properties it presents many points of resem- blance to carbon in its chemical compounds. It is a silver-white metal, soft, ductile, of crystalline structure, melting point 228°C, vaporizable at white heat. It does not oxidize on exposure to air, and is, therefore, used to coat iron ware. Tin also enters into several very useful alloys. This metal occurs in nature as stannic oxide, called " tin- stone," or'" tin ore." Compounds of tin are mostly white or colorless, and are made from the metal or its chloride. 758. "Tin salt" is chloride of tin, SnCl 2 , and is used as a mordant in dyeing. It is soluble in water containing hydro- cloric acid. 759. Titanium is also chemically a relative of carbon, but it is so rare an element that it will not be described here. 760. The carbon group and the nitrogen group, side by side, show some interesting parallels: CHEMISTRY. *95 Negative Tetrad; Negative Polyvalent Perissads. Carbon . . Silicon Titanium. Tin Atomic Weight. \ Atomic Weight. 12 14 Nitrogen 28.3 j 31 Phosphorus 48 51 ■ Vanadium 75 Arsenic 120 Antimony 205 Bismuth CHAPTER XXXVI. SUMMARY. 761. The electro- negative monads and dyads are salt- formers. They are active agents in producing compound radicals, which they do by saturating only a portion of the valence units of the trivalent and quadrivalent electro-negative elements. Oxygen and hydrogen are of the greatest importance in the relations between other elements and their most numerous com- pounds. While these two elements are the principal active agents in forming compound radicals, they are opposite to each other, in this respect: Oxygen characterizes the negative com- pound radicals, while hydrogen characterizes the positive com- pound radicals. The electro-negative, trivalent and quadrivalent elements are not salt-formers; they are passive agents in the formation of compound radicals, and act as links, centers, and skeletons, by which radicals are united into molecules. 196 CHEMISTRY. CHAPTER XXXVII. THE LIGHT METALS. 762. The uniformly electro-positive elements are all metals. These have been classified in various ways. Thus they have been divided into two groups: light metals y whose specific weights are less than 5, and lower than the specific weights of their oxides; and heavy metals, whose specific weights are over 5, and higher than the specific weights of their oxides. They have also been classified into: alkali metals; alkaline earth metals; earth metals, proper; etc. The several methods of classification adopted by different chemists must necessarily coincide in many places as they are all based upon natural rela- tionships. 763. We may first place the five strongest electro-positive metallic radicals together, in the order of their atomic weights: Atomic Weights. Lithium 7. Sodium 23. Potassium 39. Rubidium 85.2 Caesium 132.7 All these metals are monads. It will be observed that the atomic weight of sodium is exactly one-half of the sum of the atomic weights of lithium and potassium, and that of rubidium is almost exactly one-half of the sum of the atomic weights of potassium and caesium, a pretty regular gradation is apparent in the atomic weights of the whole group, and these five metals are the strongest electro-positive radicals known, from caesium to lithium, in just the order in which their atomic weights place them; caesium being the strongest alkali metal, and lithium the least pronounced alkali metal. 764. As this group includes all of the alkali metals, the table becomes all the more significant. Still greater emphasis will be given to this exhibit if we place opposite the alkali metals all dyad metals having nearly coincident atomic weights: CHEMISTRY. I 97 Dyads. Atomic Weights. Glucinum g. Magnesium 24. Calcium 40. Strontium 87.3 Barium 137. Monads. Atomic Weights. 7 Lithium 23 Sodium 30- Potassium 85-2 Rubidium 132.7 Caesium These five dyad metals stand next after the alkali metals in the electro-chemical series in precisely the order in which they stand in the preceding table, beginning with barium and ending with glucinum. All of the ten metals included in the table are light metals, and all the " light metals" (762) are included except Aluminum (with the atomic weight 27) and the rare metals Yttrium (At. wt. 89), Zirconium (At. wt. 90.4), Lanth- anum (At. wt. 138), Cerium (At. wt. 140), Didymium(At. wt. 142 now split up into two elements), Erbium (At. wt. 166) and Thorium (At. wt. 232), which are not so well known. 765. The alkali metals, then, are all monads, and have low specific weights; their hydrates, or compounds with HO, are the true alkalies, which are very readily water soluble (with the exception of lithium hydrate which is not readily soluble); their normal carbonates and phosphates are also freely water soluble (except those of lithium, which are rather sparingly soluble). Their carbonates and hydrates are not decomposed by heat. Their normal salts have either an alkaline or a neutral reaction on test paper. 766. The alkali metals have such intense chemical affinity for oxygen that they must be kept immersed in naphtha. They even decompose water, appropriating the oxygen so that the hydrogen is liberated. Caesium decomposes water with great violence; lithium more quietly. These metals also have an intense affinity for the halogens and sulphur. Observe that the alkali metals decompose water by taking to themselves its oxy- gen, while chlorine decomposes water by uniting with the chlorine. I98 CHEMISTRY. Potassium oxide is K 2 0. It reacts with water so violently that flame results. The oxides of the alkali metals form hydrates when they come in contact with water. 767. Potassium (K; at. w. 39) exists in nature only in compounds. In minerals as silicate; in the salt deposits at Stassfurth, Germany, it is contained in the form of chloride; and the ashes of plants contain potassium carbonate. The juice of grapes contains acid tartrate of potassium, which deposits on the bottom and sides of wine vats and casks in the form called argots or crude tartar, which, when freed from color- ing matter and other impurities, furnishes cream of tartar, 768. Potassium is a soft bluish white metal which oxidizes rapidly when exposed to the air, and decomposes water, from which it appropriates the oxygen. It is produced by strongly heating K 2 C0 3 with C 2 , the reduced metal being distilled over. To protect the metallic potassium from oxidation it is kept in some liquid hydrocarbon, as in petroleum. 769. The potassium compounds are, as a rule, colorless or white. They are either alkaline or salty to the taste. They are frequently anhydrous, generally water-soluble, and the hydrate, carbonate and acetate are deliquescent. Of the common potas- sium compounds of the drug store the least soluble are the acid tartrate or cream of tartar, the sulphate, chlorate, and perman- ganate. 770. The materials employed for making potassium prepa- rations are first the crude chloride from Stassfurth, then the carbonate made from that chloride, and the bicarbonate. The pharmacopoeias prefer the bicarbonate as the material from which to prepare the other potassium compounds, because the bicarbonate is crystallized and generally sufficiently pure as well as cheap. The most common potassium compounds are the hydrate, carbonate, bicarbonate, bromide, iodide, nitrate, chlorate, per- manganate, acetate, citrate, tartrate and bitartrate, all of which are described in the Pharmacopoeia. A solution of potassium hydrate, called " liquor potassse " is also official. CHEMISTRY. 1 99 Potassium hydrate, KOH ("potassa '*'),- is extremely caustic and corrosive, and, therefore, poisonous. Even the carbonate ("potash," or " pearl-ash," or " salt of tartar") is destructive and poisonous when introduced into the body without sufficient previous dilution or in too large quantities. The best antidotes are vinegar, lemon juice, citric acid, olive oil, cotton seed oil, milk, etc. " Saltpetre " is potassium nitrate. 771. Sodium (Na; at. w. 23) occurs most commonly as chloride of sodium, which constitutes " salt." From this the carbonate ("sal sodae ") is manufactured on a large scale. It is a soft, silver-white metal which, like potassium, must be kept in hydrocarbons to keep it from oxidizing, and it is pro- duced from sodium carbonate by a process analogous to that by which K 2 is made. 772. Compounds of sodium are, as a rule, white or color- less, and water-soluble. Their taste is either alkaline or purely salty, or bitterish. Water of crystallization occurs more com- monly in sodium salts than in the salts of potassium, and many of the crystallized sodium salts effloresce when exposed. 773- Sodium preparations are made from the carbonate which is both cheap and generally sufficiently pure, being crys- tallized. The most commonly used sodium compounds are the hydrate, carbonate, bicarbonate, chloride, bromide, nitrate, sulphate, phos- phate, acetate, salicylate, and the tartrate of potassium and sodium. There is also an official solution of the hydrate, Na - '- 1. Sodium hydrate is called " soda " by the Pharmacopoeia; "washing soda" is the crystallized sodium carbonate; and *' baking soda" is the bicarbonate. The sulphate is sometimes called "Glauber's salt," and the tartrate of potassium and sodium is"Rochelle salt." 774. Lithium (Li; at. w. 7) is a comparatively rare metal, and its compounds, therefore, expensive. The most compounds are the carbonate, bromide, chloride, citrate and salicylate. They are all white, and prepared from the carbonate derived from the mineral lepidolite. 200 CHEMISTRY. 775. Ammonium is XH,, a positive compound radical which forms salts in many respects closely resembling those of K, Xa, and Li. It indeed behaves as if it were a compound alkali metal. Ammonia, or hydrogen nitride, H 3 X, is contained in the gas liquor obtained in the manufacture of illuminating gas, and, when purified, this ammonia is now the chief material used for the production of the ammonium compounds. Ammonium compounds are white or colorless, and water- soluble. All are odorless except the hydrate and the carbon- ate, which have the strong odor of ammonia; all ammonium compounds develop the odor of ammonia on the addition of potassium hydrate or sodium hydrate. Their taste is alkaline, or salty ; sometimes bitterish. The most common ammonium compounds are the hydrate, carbonate, chloride, bromide, nitrate and acetate. Ammonium hydrate is contained in the "water of ammonia'' of the pharma- copoeias ; it is sometimes called "caustic ammonia," and also u spirit of hartshorn. " The "carbonate of ammonium " of the Pharmacopoeia is a complex substance containing carbamate as well as carbonate ; this mixed salt is sometimes called "salt of hartshorn," and also " sal volatile." Ammonium chloride is often called '"'muriate of ammonia," and also "sal ammoniac." 776. The alkaline earth metals are calcium, strontium and barium. They are dyads, and have low specific weights. Like the alkali metals they have such an intense affinity for oxygen that they decompose water. Their oxides, however, can be kept and do not react with water so violently as do the oxides of the alkali metals. Their hydrates are only sparingly soluble in water, and their normal carbonates as well as their phosphates are insoluble, while their acid carbonates are water-soluble to a small extent. Their normal salts, as far as water-soluble, have a neutral reaction on test paper. The sulphides are water-soluble. The sulphates and oxalates are insoluble. CHEMISTRY. 20 1 By reference to the comparative exhibit on page 197 it will be seen that the atomic weight of strontium is very nearly one- half of the sum of the atomic weights of calcium and barium. Barium is the strongest electro-positive dyad, strontium the second; and calcium, the third 777. Calcium (Ca; at. w. 40) occurs abundantly in the form of lime-stone and other calcium compounds. The metal is light-yellowish. " Chalk " and " marble " are calcium carbonate, and " lime " (" quick-lime ") is calcium oxide, while "slaked lime " is cal- cium hydrate. The most abundant and convenient materials for preparing calcium compounds are the carbonate and the chloride. The chloride, which is freely soluble in water, is made by saturat- ing hydrochloric acid with calcium carbonate, the many insol- uble calcium compounds are made by precipitation - from the chloride. The oxide (" lime ") has the name " calx " in Latin and the words calcium and calcination are derived from it. When common lime-stone (impure calcium carbonate) is strongly heated in the "lime-kiln," it is said to be calci?ied, the carbon- ate being decomposed into oxide and C0 2 : CaC0 3 =CaO-r-C0 3 . When the lime or calcium oxide is put into water, or when water is added to the lime, calcium hydrate is formed: CaO+H 2 = Ca(OH) 2 . The lime water of the drug stores, then, is solution of cal- cium hydrate. The most common calcium compounds not already named are the precipitated calcium carbonate, prepared chalk, dried sulphate of calcium, and the phosphate of calcium. " Plaster of paris " is the dried sulphate of calcium, which when mixed with water unites with it chemically to form a hard crystalline solid. " Bone-ash " is calcium phosphate from " calcined bones." Z02 CHEMIST] Preparations of calcium are white or colorless. The insolu- ble are tasteless: others have a disagreeable caustic or bitterish taste. 778. Strontium (Sr; at. w. 87.3) is of comparatively little importance to pharmacists; and even Barium (Ba; at. w. 157) is of minor interest. The hydrates of Ca, Sr, and Ba are sparingly soluble in water their carbonates, phosphates, sulphates and oxalates insoluble. 779. The next group, naturally following those of the alkali metals and the alkaline earth metals, is the zinc group. Glucinum (At. wt. 9) is often classed in this group, but as it is a rare metal we shall omit further mention c: it. The zinc group, then, consists of: Atomic Weight. Magnesium 24 Zinc 65 C^-mium 112 It will be seen that in this group, again, the atomic weight of the middle member is about one-half of the sum of the atomic weights of the other two; but in this case the metal having the lowest atomic weight is the strongest positive element and the metal having the largest atomic weight is the weakest. But all are strongly electro-positive radicals. They are dyads. These metals do not exhibit so strong an affinity for oxygen as those before considered: they may even be freely exposed to the air without becoming oxidized. Their hydrates are not water-soluble; but zinc hydrate is soluble in solution of potassi- um hydrate or of ammonium hydrate. Their carbonates, phos- phates and sulphides are insoluble; but the sulphates, soluble. The carbonates of these metals, precipitated from the solu- tions of their water-soluble salts by alkali carbonates are not normal but basic (containing hydrate as well as carbonate); but normal magnesium carbonate can be prepared in other ways. 780. But we will take up zinc later and treat for the pres- ent of magnesium and aluminum, only, because zinc is decid- ed".;.- one of the heavy metals. The medicinal effects of the compounds of the light metals CHEMISTRY. 203 are alkaline, antacid, laxative and cathartic, except so far only as other medicinal properties are imparted to them by the negative radicals they contain. They are poisonous only when corrosive or chemically destructive. In this they differ from the compounds of the heavy metals, which, with the exception of the iron compounds, are poisonous, and all of which have more decided medicinal properties deter- mined by their positive radicals. 781. Magnesium (Mg; at. w. 24.3) occurs as carbonate and silicate, and in spring waters as sulphate and chloride. Talcum and asbestos are magnesium silicate with carbonate. The principal material used for the production of other magnesium compounds is the native carbonate. From this the sulphate may be made, and the sulphate is used for the pro- duction of purer carbonate and other compounds. The metal is silver-white, can be ignited, and burns with a most intense light to magnesium oxide. 782. The compounds of magnesium are white or colorless, tasteless when insoluble, bitter when soluble, except the citrate. The most commonly used insoluble magnesium compounds are the oxide and carbonate; the soluble are the sulphate and citrate; chloride is much used in the manufacture of mineral waters. Magnesium oxide is called (t magnesia " by the Pharma- copoeia, and is also frequently called "calcined magnesia," because it is made by heating the carbonate. The magnesium carbonate of the pharmacopoeias is not the normal carbonate, but a compound of carbonate and hydrate. Sulphate of mag- nesium is commonly called " Epsom salt," because it is contained in the water of the Epsom Springs, England. 783. Aluminum (Al), a tetrad metal with the atomic weight 27, stands alone. It is destined to be one of the most important of all metals in the near future, for it does not oxidize in air at any tempera- ture, and dilute acids have scarcely any effect upon it, except hydrochloric acid. 204 CHEMISTRY. Aluminic salts contain two atoms of aluminum tied together so that but six of the eight bonds are free to combine with other radicals (786). The most common salt is "alum." All water-soluble alumi- num compounds are astringents. Sulphate, chloride, nitrate and acetate are water-soluble ; hydrate and phosphate, insoluble ; carbonate does not exist. CHAPTER XXXVIII. THE HEAVY METALS. 784. Zinc (Zn; at. w. 65.1) is a bluish-white metal of crys- talline structure ; sp. w. 7.2 ; melting point, 412° C; volatilizes at about i,ooo° C. It occurs as calamine, which consists of carbonate and silicate, and as zinc blende, which is sulphide. The metal is obtained by reducing the ore with carbon at a high heat. 785. Zinc compounds are white or colorless, and when •soluble they have a disagreeable, bitter, astringent, metallic taste, and are poisonous. The materials used for the preparation of officinal zinc com- pounds are the metal, oxide, carbonate and sulphate. The sul- phate is made by dissolving the metal in dilute sulphuric acid, the carbonate from the sulphate by precipitation with sodium carbonate, the oxide by calcining the carbonate, and the acetate as well as other soluble salts by saturating the proper acid with the oxide or carbonate. 786. The Iron Group. — This group is a peculiar one. Its members are : Atomic Weight. Chromium, 52. Manganese, 55. Iron, 56. Nickel, 58.6 Cobalt, . 5S.6 CHEMISTRY. 205 The atomic weights of all, it will be observed, are nearly the same. Like aluminum, these metals are pseudo-triads — that is, they form series of compounds in which two atoms of the metal are tied to each other and act together as one radical with six free bonds, thus : II II -Al— Al— — Fe— Fe— II II But while aluminum never acts as a dyad or a hexad, the metals of the iron group seem to have three separate valences, although nickel and cobalt do not exhibit decided evidences of sexivalence. The metals of the iron group have two principal series of compounds — the -ous compounds, in which they act as dyads, and the -ic compounds, in which they act as tetrads, two atoms, tied together, acting each as a pseudo-triad. For convenience, the metals themselves are distinguished by their own derived adjectives with the terminations -ous and -ic to specify their respective valence. Thus ferrous iron is a bivalent iron atom ; ferric iron is two tetrad atoms tied together, and together acting as a pseudo-triad. In the same manner we speak of chromous chromium and chromic chromium; man- ganous manganese and manganic manganese; nickelous nickel and nickelic nickel; cobaltous cobalt and cobaltic cobalt. These metals are slowly oxidized in air, and do not exhibit great chemical energy ; and their compounds are not as stable as those of the metals before described. Their oxides, hydrates, phosphates and sulphides are insoluble. Their carbonates are so unstable as to begin to decompose rather rapidly as soon as they have been formed. Their nitrates, sulphates and haloids are readily water-soluble. 787. Iron (Fe ; at. w. 56) is one of the most common and familiar of the metals. The best iron ore is the magnetic oxide of iron, or ferroso-ferric oxide. The metal is obtained from the ore by reduction with charcoal at high heat. There are three distinct forms of commercial iron — steel, cast iron, and wrought iron, differing in properties according to the amount of carbon they contain. 206 CHEMISTRY. 788. There are two classes of iron co m pound s— ferrous compounds, which contain ferrous iron (Fe) ; and ferric compounds containing ferric iron (Fe 2 ). The ferrous compounds are generally green or greenish blue when they contain water, white or nearly white when dry. The ferric compounds are reddish-brown, or yellowish-red when containing water, white or pale yellow when dry. But some iron compounds have a lively blue color (as " Prus- sian Blue"), others a pure yellow color (as the oxalate), and other colors are represented by them. Ferrous compounds are produced from metallic iron or from ferrous sulphate. Ferric compounds are made from ferric sul- phate or chloride, or from ferric hydrate, or by changing the ferrous compounds to ferric by means of nitric acid or chlorine. As iron dissolves readily in either hydrochloric or sulphuric acid, the ferrous chlorides and sulphates are easily made by sat- urating these acids with the metal. The iron compounds used in medicine are numerous. When water-soluble they usually have a peculiar inky or styptic astrin- gent taste, except the " scale salts " which are comparatively free from the disagreeably inky taste. " Green vitriol " is ferrous sulphate. "Tincture of Iron " contains ferric chloride. 789. Lead (Pb ; at. w. 206.4) is also a common metal, com- paratively soft, and of great density, melting at 325 C. It occurs most commonly as galena, which is lead sulphide. The metal is obtained from this ore. It is preferably a tetrad, but sometimes also acts as a dyad. Besides these variations in its valence it also has the oxide Pb 2 0, in which it must be assumed that the two lead atoms are tied together. See Silver (797). Lead does not oxidize except superficially in the air. It has greater affinity for sulphur than for oxygen. The carbonate of lead is a basic carbonate similar in composition to the carbonates of the metals of the zinc group. CHEMISTRY. 207 Lead compounds are of various colors, some white, others colorless, others red, yellow or black. The nitrate and the acetate are the only water-soluble lead salts. They are poison- ous, and even the insoluble lead compounds are poisonous because they slowly yield sufficient quantities of soluble lead compounds to produce the poisonous effects. The nitrate and acetate serve as materials for the production of most of the other lead compounds. 791. Copper and Mercury. — These two metals are uni- formly bivalent in their compounds. Their atomic weights are: Atomic V/ eight. Copper 63.2 Mercury 200 They have been grouped in several different ways with other metals (793). Notwithstanding their uniform valence, they have two series of compounds — the -ous compounds containing mercurous mer- cury ( — Hg — Hg — ) or cuprous copper ( — Cu — Cu — ), and the -ic compounds formed by mercuric mercury ( — Hg — ) and cupric copper ( — Cu — ). The metals are not readily oxidized in air without the aid of heat. The oxides of copper are stable compounds; those of mercury readily decomposed by heat. The hydrates, phosphates and sulphides are insoluble. Normal carbonates do not exist; the basic carbonates are insoluble. Sulphate, nitrate and chloride of cupric copper are water-soluble. Cuprous salts are rare and unstable. The only water-soluble mercury compounds are the mer- curic chloride and mercuric cyanide. Nitrates of mercurous and mercuric mercury and mercuric sulphate are decomposed by water. 792. Copper (Cu; at. w. 63.2) is a reddish metal, harder than lead, but softer than iron; it does not become tarnished in dry air. It occurs in the free state in large quantities. The only common copper compounds used in pharmaceu- tical work and in medicine is the sulphate, which is a blue, crys- 208 CHEMISTRY. tallized, water-soluble salt, often called blue vitriol. Other cop- per compounds are blue, green, brown, or black. All are poi- sonous. 793. Mercury (Hg; at. w. 200) is the only liquid metal. It is silver white, and is also called quicksilver. Sp. w. 13.6. Boils at 360 C. It occurs in the form of sulphide, or cinnabar. All mercury compounds are more or less poisonous, and their poisonous character is as usual in the ratio of their solu- bility, the mercuric compounds being more dangerous than the mercurous. The metal itself, however, does not have a poison- ous effect. Mercury compounds are white, colorless, red, yellow, or black. Only mercuric chloride and mercuric cyanide are water- soluble. Mercury nitrates decompose on contact with water. 794. The materials used for making compounds of mer- cury are the metal itself and the mercuric chloride. The solution of nitrate of mercury in water containing nitric acid is also used. Sulphate of mercury is prepared by heating the metal with sulphuric acid, and the sulphate is then used for prepar- ing calomel and corrosive sublimate, by double decomposition with sodium chloride, the mixture being subjected to sublima- tion. 795. Among the most important preparations of mercury are blue mass, blue ointment and mercury with chalk, all of which contain finely divided metallic mercury, and the official compounds of mercury include the red and yellow oxide, the chlorides and iodides, the mercuric sulphate and subsulphate and white precipitate. "Calomel," or "mild chloride of mercury," is the mercurous chloride, Hg 2 Cl 2 . " Corrosive sublimate," or" corrosive chloride of mercury," is mercuric chloride, HgCl 2 . "Red precipitate," or "red oxide of mercury/' is mercuric oxide prepared by decomposing the nitrate by heat; it is not a precipitate. The "yellow oxide of mercury" is also mercuric CHEMISTRY . 2O0 oxide made by precipitation resulting from double decompo- sition between mercuric chloride and potassium hydrate. " Green Iodide of mercury " is mercurous iodide; " red iodide of mercury" is mercuric iodide. "White precipitate" is mercur-ammonium chloride, NHgHgCI. 796. Silver (Ag; at. w. 107.7) * s a beautiful white metal, capable of receiving a high polish; soft, ductile, not tarnished in pure, dry air. It occurs free as well as in the form of sulphide. The only silver compound much used is the nitrate which is obtained by dissolving the metal in nitric acid, and the product is either crystallized or fused and moulded into sticks or pencils. Silver nitrate, when cast into cylindrical sticks, is often called "lunar caustic." Silver oxide is seldom used. It is a dark brown, insoluble powder. 797. Silver is a metal which has been placed by many chemists in the same group with potassium, sodium and lithium. Others class it with lead and copper. By reason of its specific heat and for other reasons it has been recog- nized as a monad, and on that account assigned a place beside the alkali metals. Its atomic weight is 107.7, which would place it between rubidium and caesium. Although silver exhibits but slight affinity for oxygen, it forms one of the most powerful bases. Nevertheless, it is a metal of high specific weight ; not affected by air, oxygen, or water ; and its compounds do not resemble those of the alkali metals to such an extent as to justify its assignment to the group of potassium, sodium and lithium. Its oxides correspond perfectly with those of lead, and its only readily water-soluble salt is the nitrate, while the acetate is slightly soluble ; these are the only water-soluble salts of lead, too. 798. It is interesting to note that the only other perissad metal which has some compounds reminding us of the alkali metals is thallium, which also exhibits some relationship to lead, has very nearly the same atomic weight as lead, and is often placed together with lead in what is then called the lead group, containing only these two metals. The properties of thallium and its compounds have been described as intermediate between those of lead and the alkali metals, and their compounds. The hydrate, carbonate and sulphate of thallium are water-soluble. 2IO CHEMISTRY. 799- Many chemists put gold, silver and the platinum group together ; others put silver, copper and mercury together ; others, again, place lead and platinum in the same group, gold and thallium in another, and copper and mercury in a third group. All these facts prove that it is still extremely difficult to effect a classifica- tion so natural as to receive general acceptance. The following exhibit of the atomic weights of artiad metals with their parallel perissads is suggestive : ARTIAD5. Atomic Weight. Palladium 107. Platinum 195 . Lead 207. PERISSADS. Atomic Weight. 108 m . . Silver 197 Gold 204 Thallium In Mendeleeff's table (664), upon which most of this chapter is based, we find copper, silver and mercury together in one column, beside the alkali metals, where they naturally fall by reason of their atomic weights, and it is a remark- able fact that all of them have corresponding oxides, Ag 3 0, Cu s O and Hg 3 0, like those of the alkali metals, K 3 0, Na 3 and Li 3 0. But gold, lead and thallium also have analogous oxides, Au s O, Pb 3 and T1 3 0. 800. Gold appears to be generally a triad, but also some- times a monad, having such compounds as AuCl 3 and AuCl, Au 2 3 and Au 2 0, etc. Its atomic weight is 196.7. It is one of the weakest of the metallic radicals, nearly all its compounds being very unstable. The metal itself is not affected by oxy- gen, sulphur or acids. The only reagent which will attack and dissolve gold is "aqua regia " or some other solution of free chlorine. Occurs in nature in the free state only. (See also preceding paragraph.) 801. The Platinum Group. — The metals of this group occur in nature only in the free metallic state. They are: Atomic Weight. Ruthenium 101.4 Rhodium 103. Palladium 106.4 Osmium I 9°-3 Iridium *9 2 -5 Platinum J 94-3 By their atomic weights, therefore, they fall into two groups, three of CHEMISTRY. 211 them having atomic weights of from 101.4 to 106.4, the others from 190.7 to 194 3. The specific weights correspond in the same ratio, the first three having the sp. w. 12 and the others 21. Relatively the greatest similarity exists between: Platinum and palladium. Iridium and rhodium. Ruthenium and osmium. Pt and Pd exhibit bivalence and quadri valence; the others also sexi va- lence. But the ruling valence of Pt and Pd is 2, and that of Ru and Os, 6; while Ir and Rh occupy the middle ground. No acids attack any of these metals; they are not directly affected by oxygen or sulphur, but free chlorine (in "aqua regia ") attacks them. Their alloys, however, dissolve in the stronger acids. Soluble double salts are the least unstable com- pounds of the platinum metals; all their other compounds are extremely unstable. CHAPTER XXXIX. SUMMARY OF METALS. 802. The electro-positive elements, or metals, omitting very rare elements, may now be reviewed in a general way, with the following conclusions: The alkali metals possess such energetic affinity for oxygen that they oxidize completely and even violently in either air or water. The alkaline earth metals do not oxidize in air as rapidly as the alkali metals, but still completely; and they decompose water, though with less violence than the alkali metals. No other metals oxidize perfectly in either air or water, at ordinary temperatures, and the direct affinity for oxygen is entirely absent in aluminum, silver, gold and the platinum metals. 212 CHEMISTRY. The oxides of alkali metals react with water to form hydrates with such energy that they are instantly changed, and with evo- lution of great heat, if permitted to come in contact with moisture. The oxides of the alkaline earth metals may be kept in dry air, but are hydrated by water, though with far less rapidity and heat than the alkali oxides. The oxides of other metals are not readily or completely hydrated when brought in contact with water. The hydrates of alkali metals are freely water-soluble, except the lithium hydrate. Lithium stands midway between the other alkali metals and the alkaline earth metals, the hydrates of which are very sparingly water-soluble. The oxides and hydrates of all other metals are insoluble in water. The only normal carbonates are those of the alkali metals, thallium and the alkaline earth metals ; but the carbonates of potassium and sodium are very freely soluble, those of lithium and thallium comparatively sparingly, and those of the alkaline earth metals insoluble in water. The carbonates of the metals of the zinc group and of lead are basic, and insoluble in water. All metallic carbonates, except those of the alkali metals, are decomposed by heat. Of many of the heavy metals, no car- bonates exist. The only water-soluble phosphates are those of potassium, sodium and ammonium — the same positive salt radicals which have soluble carbonates. The only water-soluble metallic sulphides are those of the alkali metals and the alkaline earth metals. Soluble sulphates are formed by the alkali metals, thallium, the zinc, aluminum and iron groups, and copper ; the sulphates of the alkaline earth metals and lead are insoluble, and that of mercury is decomposed by water. All metallic chlorides are water-soluble, except those of silver, lead, thallium and mercurous mercury. Chloride of antimony is decomposed by water. CHEMISTRY. 213 The metallic nitrates are all water-soiuble, except those of mercury and bismuth, which are decomposed by water. The compounds of the alkali metals are the most numerous and generally very stable or permanent ; they are also either neutral or of alkaline reaction to test paper. The salts of the alkaline earth metals are also comparatively stable, and usually of neutral reaction; and next in order those of the metals of the zinc group. The salts of other metals are less permanent and frequently of acid reaction, and the compounds of mer- cury, silver, gold and platinum generally unstable and compara- tively few. CHAPTER XL. COMPOUND RADICALS. 803. Atoms unite with other atoms either singly or in groups. When a chlorine atom unites with another chlorine atom to form a molecule of chlorine, or with a hydrogen atom to form a molecule of hydrogen chloride, commonly called hydrochloric acid, each of these atoms exercises active chemical energy or affinity in the creation of the molecule; and when zinc is dissolved in the solution of the hydrogen chloride the reaction which sets in produces mole- cules of zinc chloride and hydrogen, each chlorine atom passing from the molecule of hydrochloric acid to the new molecule of zinc chloride; from this molecule of zinc chloride the chlorine atoms can be transferred to still another molecule — that of silver chloride — by mixing a solution of the zinc chloride with a solution of silver nitrate. At the same time the silver which unites with the chlorine to form the silver chloride must part from the group of atoms with which it was combined in the silver nitrate and that group unites with the zinc which was robbed of its chlorine by the silver. In this last re- action, then, we have both single atoms and groups of atoms passing from one molecule to another. Atoms of different kinds very commonly travel together in certain definite groups, the several atoms in such a group being united to each other while 214 CHEMISTRY. some one of the atoms in the group still has one or more unsatisfied valence units or free bonds, by which the whole group may thus be united to some other atom or group of atoms. Thus, all nitrates contain the group N0 3 , consisting of one nitrogen atom and three oxygen atoms, and in that group one of the oxygen atoms must have one unsatisfied bond or valence unit left, for nitrogen acts here as a pen- tad and oxygen is always a dyad, so that three oxygen atoms have six valence units together. The group N0 3 is called the nitrate group or the nitrate radical, because all nitrates contain this characteristic group; every com- pound containing this group is a nitrate, and no compound is a nitrate that does not contain it. The nitrate group or nitrate radical united to a hydro- gen atom makes nitric acid= HNO a . If we place a piece of silver in the solu- tion of nitric acid a reaction ensues, and that product of the reaction which remains in the liquid is the salt called silver nitrate = AgN0 3 . The molecule of nitric acid, HN0 3 , has, then, become transformed into the new molecule AgN0 3 by the exchange of an atom of hydrogen for one of silver; but the nitrate group has passed into the new molecule unaltered. Lead put in the solu- tion of silver nitrate will take the nitrate radical away from the silver and cause the liberated silver atoms to form molecules of silver which separate from the liquid in the solid state as a blackish powder. The lead nitrate is Pb(N0 3 ) 2 because lead is a dyad or has two bonds or valence units, while, as we have seen, the nitrate radical has only one, and we must accordingly have two nitrate groups to satisfy one atom of lead. Copper placed in the solution of lead nitrate usurps the place of the lead producing copper nitrate = Cu(N0 3 ) 2 , while lead is precipitated. From the copper nitrate the nitrate radical can in turn be transferred to iron nitrate by putting iron in the solution of the copper nitrate; the iron nitrate is Fe(N0 3 ) 2 . Now we might mix the solution of iron nitrate with a solution of sodium carbonate, which would result in double decomposition (529), the products being iron carbonate and sodium nitrate = NaNO s . Thus, we have transferred the nitrate radical, N0 3 , from molecule to molecule, uniting it successively to several different positive radicals. There are many other compound radicals besides N0 3 , and all can be transferred from one molecule to another. 804. Compound radicals are groups of atoms united to each other but having one or more unsatisfied valence units or free bonds. They, therefore, act in the same manner as free atoms, being united by their free bonds toother radicals of opposite electro- chemical polarity. Compound radicals have an invariable valence. CHEMISTRY. 215 805. All oxysalts (900) contain compound radicals. The sulphates all contain the characteristic sulphate radical S0 4 ;all compounds containing the radical CO s are carbonates ; no com- pound can be a phosphate unless it contain the radical P0 4 ; all chlorates contain the group C10 3 : and the group CgO^ distin- guishes the oxalates. 806. The compound radicals as well as the elemental radi- cals may be divided into two great classes — -positive and negative radicals. Compound radicals containing oxygen but no hydro- gen are as a rule electro-negative ; those containing hydrogen but no oxygen are as a rule electro-positive. But there are many negative compound radicals containing both oxygen and hydrogen together with carbon, and also many positive radicals containing the same elements. 807. Hydrogen and oxygen together form the very impor- tant compound radical HO, or OH, called hydroxyl.. This radi- cal combines with itself to form the so-called peroxide of hydro- gen = H 2 2 . It unites with many of the metals to form hydrates or hydroxides, and with many different negative radicals to form acids; with one hydrogen atom and any number of groups of CH 2 the hydroxyl forms alcohols, and all alcohols contain HO. It is, of course, univalent since the hydrogen atom has but one bond which ties only one of the two bonds of the oxygen atom, leaving one oxygen bond free. 808. Nomenclature of the compound radicals. They have been given names with the termination -yl, as, for instance, hydroxyl, carbonyl, carboxyl, nitryl, nitrosyl, sulphuryl, phos- phoryl, methyl, ethyl, amyl, glyceryl, phenyl, acetyl, bismuthyl, antimonyl, etc. But many compound radicals have names which are not in accordance with this system. 2l6 CHEMISTRY. 809. Acid-forming radicals are those which form acids when united to the radical hydroxyl, HO. The principal acid- forming radicals of inorganic chemistry are : Radical. Acid Formed. CI CIO cio 2 CIO3 HO.C1 HO.CIO HO.CIO, HO.C10 3 Hypochlorous Chlorous Chloric Perchloric SO so 2 s 2 o (HO) 2 .SO (HO) 2 .S0 2 (HO) 2 .S 2 Sulphurous Sulphuric Thiosulphuric NO N0 2 HO. NO HO.N0 2 Nitrous Nitric H 2 PO HPO PO p 2 o 3 po 2 HAsO AsO As 2 3 HO.H 2 PO (HO) 2 .HPO (HO) 3 .PO (HO),P 2 3 HO.P0 2 (HO) 2 HAsO (HO) 3 .AsO (HO) 4 .As 2 3 Hypophosphorous Phosphorous Orthophosphoric Pyrophosphoric Metaphosphoric Arsenous Arsenic Pyroarsenic HSbO Sb0 2 (HO) 2 .HSbO HO.SbO, Antimonous Metantimonic B B 4 5 (HO),.B (HO),BA Boric Pyroboric CO CO CN SiO (HO) 2 CO (HO),. (CO), HO.CN (HO) 2 .SiO Carbonic Oxalic Cyanic Silicic SnO (HO) 2 .SnO Stannic Cr0 2 Cr 2 5 Mn 2 6 (HO) 2 .Cr0 2 (HO) 2 .Cr 2 5 (HO),Mn 2 Q 6 Chromic Dichromic Permanganic CHEMISTRY. 217 810. The principal positive compound radicals of inor- ganic chemistry are : Ammonium, NH 4 . Antimonyl, SbO. Bismuthyl, BiO. Mercur-amraonium, NH 3 Hg. Ammonium is the radical contained in all ammonium salts and other ammonium compounds. Antimonyl occurs in the so-called " tartrate of antimony and potassium;" bismuthyl, in so-called "subnitrate of bismuth;" and mercur-ammonium, in so-called " ammoniated mercury." 811. In organic chemistry the most important compound radi- cals of common occurrence or of special interest to pharmacists are the following: Positive compound radicals: NH t Ammonium CH 3 Methyl CH 2 Methene CH Methenyl C 2 H 5 Ethyl C 5 H n Amyl C 6 H 5 Phenyl C 3 H 5 Glyceryl C 2 H 3 Acetyl (CH3.CO.) Negative compound radicals: HO Hydroxyl CO Carbonyl NO Nitrosyl N0 2 Nitryl CN Cyanogen CNS Sulphocyanogen 8l2. In paragraph 809 the radicals which form acids with the radical HO are enumerated, and the formulas and names of the acids are placed opposite the corresponding radicals, respect- ively. Thus you find that the radical which forms sulphuric acid by 2lS CHEMISTRY uniting with hydroxy] HO. is SO.> (sulphuryl), and the formula for sulphuric acid is given as (HO)..SOo. This is a very explicit formula, showing that sulphuric acid consists of one group of atoms represented by SO., and two groups such as are called hydroxyl. HO. But for the sake of convenience the formula for sulphuric acid is not written as above (HO) 2 S0 2 . but instead it is written HgSO*. We will now explain this. 813. That SOo is a bivalent radical you can readily ascer- tain for yourself when you know that in sulphuric acid and all other sulphates the sulphur atom is a hexad. There must accordinglybe six sulphur bonds and four oxygen bonds in SO- 2 . leaving two sulphur bonds free. These are each united to one group of hydroxyl. thus: O— H I o=s=o O— H which may also be more briefly written: SOo/OH \OH or still more briefly : S0 8 .(OH) a or (OH)2.S0 8l or final! v: H 8 S0 4 . 814. Whenever sulphuric acid forms a sulphate by com- bining with any base, it is only the hydrogen of the groups of hydroxyl that is exchanged, and one or both of the hydrogen atoms may be replaced by another positive radical, as you will see clearly by the following formulas: H 8 S0 4 Sulphuric Acid. KHS0 4 Acid Potassium Sulphate. K 5 S0 4 Normal Potassium " Na 2 S0 4 Sodium Sulphate. CaS0 4 Calcium FeS0 4 .XH,i 2 S0 4 Ferrous Ammonium Sulphate. CHEMISTRY. 2IQ In other words, when sulphuric acid forms a sulphate with any base or metal, the hydrogen of the hydroxyl being replaced,, the change would be most correctly represented as follows: S0 2 /0— H S0 2 /0— K \0— H NO— K Sulphuric Acid. Potassium Sulphate. But for the sake of convenience, and since the linking oxy- gen atoms of the hydroxyl remain in their position, the general practice is to write the formula for every acid not by represent- ing the radicals of which it is composed, but the replaceable hydrogen is separated from and placed in front of the rest of the formula. The remainder, after removing the hydrogen, is called an acid residue. Thus in H 2 S0 4 the H 2 is all that is replaced by another base in the formation of other sulphates, and S0 4 is the residue, and, in fact, may well be treated as a radical, because the oxygen of the hydroxyl is still united to the S0 2 , which makes it SO A . 815. This is done, then, in writing the formulas of all acids. Although all acids contain hydroxyl, only the hydrogen of the hydroxyl can be displaced or replaced in the formation of salts, and that hydrogen is written first in the formula, the residue being placed after it and considered as the characteristic acid radical. 816. Acetic acid is composed of the three radicals, CH 3 , CO and OH, and the structural formula (838) for the acetic acid molecule is therefore CH 3 .CO.OH, but it is for convenience written HC 2 H 3 2 , and sometimes it is written C 2 H 4 2 . To write formulas in such a way that the number of replaceable hydrogen atoms can at once be seen is a very valuable point, however, and, therefore, we should always write the molecule of acetic acid as HC 2 H 3 2 . As it has only one hydroxyl group it can have only one atom of basic hydrogen which can be replaced by any other positive radical ; if the other hydrogen atoms or anyone of them should be removed, exchanged or replaced, the compound would no longer be an acetate. 220 CHEMISTRY. 817. It follows from what has been stated in the preceding paragraph that we have for. every acid, inorganic or organic, an acid-radical which is shown in its molecular formula, and in the molecular formula of every salt (905). You can at once recognize any acid or a salt of any particular acid by its radical, if you learnwhat that radical is, and if you will learn not only the for- mula but also the valence of every such radical, together with the formula and valence of every positive radical of common occurrence, you will possess the knowledge necessary to con- struct the molecular formulas of all the normal compounds formed by these radicals respectively. CHAPTER LXI. TABLES OF RADICALS. 818, Tables are here given (819 and 820) of all the important and commonly occurring simple and compound radicals, positive as well as negative, grouped according to their valence, together with the generic name of the class of compounds formed by each when united to a radical of opposite electro-chemical polarity. [In the next chapter we will explain how these tables can be used, and how formulas are constructed from the radicals according to their polarity and valence.] 819. Valence of Positive Radicals. (Basylous Radicals.) Univalent. Compounds formed. H Acids K Potassium Na Sodium Li . Lithium Ag Argentic NH 4 Ammonium CH 3 Methyl C 2 H 5 Ethyl CHEMISTRY. [Basylous-Radicals.- C5H11 QH5 NH 2 Hg BiO SbO Bivalent. Ca Ba Sr Mg Zn Cd Pb Cu Cu 2 Hg Hg 2 Sn Mn Fe Co Ni Trivalent. Sb Bi C3H5 Quadrivalent . Sn Pt Sexivalent. Ce 2 Al 2 Continued. \ Amyl Phenyl Mercurammonium Bismuthyl Antimonyl Calcium Barium Strontium Magnesium Zinc Cadmium Plumbic Cupric Cuprous Mercuric Mercurous Stannous Manganous Ferrous Cobaltous Nickelous Antimonous Bismuthous Glyceryl Stannic Platinic Cerium Aluminic 222 CHEMISTRY. Mn 2 Manganic Fe 2 Ferric Cr 2 Chromic Ni 2 Nickelic Co 2 Cobaltic 820. Valence of Negative Radicals. (A cidulous Radicals.) Univalent. Forming, H Hydrides CI Chlorides Br Bromides I Iodides Fl Fluorides Cy or (CN) Cyanides HO Hydroxides (Hydrates) CIO Hypochlorites CvO or (CNO) Cyanates HS Hydrosulphides CyS or (CNS) Sulphocyanides NO" Nitrites N0 3 Nitrates H 2 P0 2 Hypophosphites CH0 2 Formiates C 2 H 3 2 Acetates C 5 H 9 2 Valerates CigH 31 2 Palmitates Ci S Ho 5 2 Stearates Ci S H 33 Oo Oleates C 3 H 5 O s Lactates C,H B S0 4 Sulphocarbolates C 6 H 2 (N0 2 ) 3 Picrates C 7 H 5 O s Salicylates C 7 H 5 2 Benzoates C 9 H 8 3 Cinnamates Bivalent. O S so 3 s 2 o 3 so, co 3 QO, HAs0 3 HSb0 3 QH 4 0, C 4 H 4 5 QH 4 6 CrQ 4 Cr 2 7 Mn0 4 Mn 2 O g B,0 7 Trivalent. P0 4 AsO* Sb0 4 B0 3 C 6 H 5 7 C 7 HO ? Quadrivalent, SiO, p 2 o 7 As 2 7 Sb 2 7 FeCy 6 B,0 7 Sexivalent. Fe 2 Cyu$ CHEMISTRY. [Acidulous-Radicals. — Continued.] 223 Oxides Sulphides Sulphites Thiosulphates Sulphates Carbonates Oxalates Arsenites Antimonites Succinates Malates Tartrates Chromates Dichromates Manganates Permanganates Pyroborates. Phosphates Arsenates Antimonates Borates Citrates Meconates Silicates Pyrophosphates Pyroarsenates Pyroantimonates Ferrocyanides Pyrobarates Ferricyanides, 224 CHEMISTRY. CHAPTER XLII. COMPOUND MOLECULES. 821. We have learnt that all molecules are made up of atoms ; that elemental molecules are made up of atoms of but one kind; and the compound molecules are made up of two or more atoms of two or more different kinds. 822. Atomicity. — The number of atoms any molecule con- tains is expressed by the term atomicity. A molecule consisting of but one atom is monatomic, a mole- cule containing two atoms (not two kinds of atoms, but two atoms, only, whether of the same kind or not) is diatomic, a molecule made up of three atoms is triatomic, one of four atoms is tetratotnic, and one of five atoms is pejitatomic, and a molecule containing six atoms is hexatomic. Molecules containing more than two atoms are polyatomic. 823. The number of atoms which may unite to form one molecule is indefinite and subject to extreme differences. Most of the elemental molecules are assumed to contain each two atoms. There are, however, elemental molecules supposed to contain one (mercury, zinc, cadmium and barium), three (oxygen as ozone), four (phosphorus and arsenic), and six (sulphur under certain conditions) atoms, respectively. Of the compound molecules all binary compounds contain but two kinds of atoms, and many of them only one of each kind. Thus the chlorides, iodides and bromides of all univalent (612) metals, and the oxides and sulphides of the bivalent (612) metals, contain but two atoms in each molecule. But molecules composed of compound radicals may contain a large number of atoms. A molecule of potassium iodide or calcium oxide contains two atoms; a molecule of water, three; ammonia, four; lead nitrate, five; copper sulphate, six; sodium sulphate, seven; phosphoric acid, eight; phenolphthalein, thirty-eight; olive oil (glyceryl oleate), one hundred and sixty-seven atoms, and the mole- cules of many organic compounds contain even a greater number of atoms. Inorganic substances have, as a rule, a far more simple molecular struc- ture than organic substances, if the present formulas of inorganic chemistry are the true ones. CHEMISTRY, 225 824. Compound molecules are formed in various ways. 1. By direct union of the component elements, as: X+Y=XY. This reaction is, however, in most cases less simple than the equation indicates. It is really not a mere addition followed by chemical union, for the elemental molecules must first be decomposed into their constituent atoms, and in many cases the direct union of atoms depends upon a change of val- ence in the factors of the reaction under the influence of energetic chemical agents, as the elevation of bivalent C to quadrivalent C, or of Civ to Cvi, or of Niii to Nv, etc. 2. Chemical reactions may also consist of apparently simple subtraction: YXZ— X=YZ+X. This is often the result of a reduction of valence of an element under the influence of high heat, as the reduction of Svi to Siv, or Nv to Niii. Exam- ples of this splitting up of one molecule into several may be found in the products of the destructive distillation of organic substances. Heat has a tendency to lower the valence of elements. But molecules may be divided by the influence of heat without any change in the valence of the atoms involved in the reaction, as when CaC0 3 is split up into CaO and C0 2 , or when phosphate of sodium is converted into sodium pyrophosphate, by heat. 3. Molecules are formed by single selective affinity when substi- tution takes place, as when zinc is dissolved in hydrochloric acid — Zn 2 +4HCl=2ZnCl 2 +2H 2 , or when chlorine is introduced into the molecule of a hydro- carbon taking the place of its hydrogen, atom for atom. 4. Double decomposition is, however, the most frequently occurring form of chemical reactions; it is much more common than the three other kinds together. In double decomposition the products of the reaction generally have the same general struct- ure as the factors, and there is simply a mutual interchange of radicals brought about by the chemical attraction working simul- taneously in two directions but toward the same result. 825. All molecules, then, are composed of radicals, and all chemical reactions take place between radicals. When two different molecules are in contact with each other there may be a mutual interchange of radicals between them ; or there may be a 226 CHEMISTRY. transfer of a radical from one molecule to another; or new radi- cals may be formed by the splitting up of existing compound radicals; or by the removal of an atom or group of atoms; or by the substitution of one atom or group of atoms *or some other atom or group of atoms; or additional radicals may be inserted between those already contained in a molecule. 826. Compound molecules are formed in accordance with the valences of the atoms or radicals of which they are consti- tuted. Equivalent (614) atoms or radicals unite directly in equal numbers, or in the ratio of one to one. Whenever any two atoms or radicals are united directly to each other, each must present the same number of free bonds. In other words, when two opposite radicals unite, there must be an equal number of bonds on each side. 827. There can be no molecule with any free bond or bonds. Every bond or valence unit presented by the atoms or radicals present in the molecule is tied or saturated. It follows from the preceding statement that the whole num- ber of bonds in any molecule must be even. Again, if there are any perissads in the molecule, their number must be even, as otherwise the total number of bonds would not be even. If there were an odd number of bonds or valence units, not all could be paired and there would then of necessity be one or more free bonds, which is impossible in a molecule. 828. Both simple and compound radicals may unite with each other directly, or they may be joined together, like links, in chains, or groups, or circles. It is evident that two equivalent atoms can only form a pair, directly united. But one dyad unites with two monads, two dyads with four monads, or with one triad and one monad, or with one tetrad; three dyads with six monads, or two triads, or with one monad, one dyad and one triad together ; etc. When more than two atoms or radicals are contained in one molecule they can not all be directly united ; but of three, four, or five radicals, one may be in the center of the whole group directly united with each of the others (713). CHEMISTRY. 227 829. Direct union of atoms. — The simplest possible com- pound molecules are those formed by two equivalent atoms. Two monads, or two dyads, or two triads, or two tetrads mutually saturate each other. Thus: H and CI, both monads, form Kand I Ag and Br, Ca and O, Zn and S, B and N, dyads, triads H— CI, or HC1 K— 1 or KI Ag — Br, or AgBr Ca=0, or CaO Zn=S, or ZnS. B=N, or BN. 830. But when the atoms or radicals are not equivalent the molecule is not so simple, for the number of free bonds on each side must then be the smallest common multiple of the numbers of their respective valence units. Thus, if the valence of one radical is 1 and that of the other 3, it follows that each radical must present three bonds ; and if one has a valence of 2 and the other of 3, each radical must present 6 bonds, or such a number of atoms or groups as will have that total number of bonds. Thus : H 1 H 1 H 1 Cu 11 Cu 2 IX Ca" S*v C*v N rn As 111 A1 2 VI K 1 (BIO)* Ba 11 Fe 11 Hg 2 " Hg" Sn'v Fe 2 VI Sbv Pb 11 and O 11 form H 2 S n SoO CU HCL n CuO On Cu 2 Cli CaCl 2 n SOo On co 2 n N 2 3 n As 2 3 CI 1 A1 2 C1 6 (OH)' KOH (OH)' BiO.OH (OH)' Ba(OH) 2 S» FeS CI 1 Hg 2 Cl 2 CI 1 HgCl a CI 1 SnCl 4 (FeCy e )'v << Fe 4 (FeCy 6 ) 3 S» SboS 5 (N0 3 )* Pb(N0 3 ) 2 2 25 CHEMISTRY. Ca 11 and (OCA) 1 form Ca(OCl) 2 (NH*) 1 " (S0 4 )« *' (NH 4 ) 2 S0 4 Fe 2 vi " (S0 4 )« " Fe 2 (S0 4 ) 3 Ca 11 " (CO3) 11 " CaC0 3 K* " (CeHaOv) 111 ^ a» Basicity. Hypochlorous Acid HCIO Monobasic Chloric Acid HCIO3 << Iodic Acid HI0 3 « Nitrous Acid HN0 2 « Nitric Acid HNO3 u Hypophosphorous Acid HH 2 PO., a Metaphosphoric Acid HPO3 u Acetic Acid HQH 3 2 C( Valeric Acid HC 5 H 9 2 u Lactic Acid HC 3 H 5 3 u Oleic Acid HQsHggO., a Phenyl-Sulphonic Acid HQH 5 SOj 7 H 2 287 Ferrous, anhydrous FeSO, *5 2 dried FeSO,.H 2 170 " cryst. FeS0 4 . 7 H 2 278 Manganous MnSO. I 5 1 cryst. MnS0 4 . 7 H 2 223 Cupric CuSO, 159.2 " cryst. CuS0 4 . 5 H a O 249.2 Mercuric HgS0 4 296 Aluminum ai;(soj 3 342 " with water Al 2 (SO i ) 3 .i8H 2 666 Potassa alum K 2 Al 2 (SO i ) 4 . 24 H 2 948 Dried alum K^A^SO,), 5i6 Ammonia alum ( NH 4 ) 2 Al 2 (SO i ) i . 24 H 2 906 Ammonio-ferric alum (NHJ 2 A1 2 (S0 4 ) 4 . 24 H 2 Fe 2 (SD 4 ) 3 964 Ferric Sulphate 400 Ferric sulphate, basic Fe 4 6(S0 4 ) 3 73o Mercuric, ba_sic (HgO) 2 .HgSO, 728 911. Thiosulphates. — The only thiosulphate of interest to pharmacists is the so-called " hyposulphite of sodium," which has the formula Na 2 S20 3# ^H 2 and the molecular weight 248. 912. Sulphites are characterized by containing the radical •5^3* which is bivalent. Sulphites are reducing agents, being con- verted into sulphates by taking up more oxygen. They are not freely soluble in water, and are generally prepared by the action of S0 2 upon hydrates, or carbonates. The solution obtained by passing the gas S0 2 into water is properly regarded as contain- ing sulphurous acid, and is so named in the Pharmacopoeia. CHEMISTRY. 265 913. The common sulphites with their molecular formulas and weights are: Names. Formulas. Molecular Weights. Hydrogen (su Iphurous H 2 S0 3 82 acid) Potassium K 2 S0 3 .2H 2 194 2 Sodium Na 2 S0 3 .7H 2 252 Calcium CaS0 3 .2H 2 156 Magnesium MgSO .6H2O 212.3 CHAPTER LI PHOSPHATES, ETC 914. Phosphates (ortho-phosphates). — The acid radical which forms the ortho-phosphates is the group P0 4 , which acts as a triad, so that ortho-phosphoric acid is tribasic. The phos- phates are very stable compounds, for the phosphate radical is a powerful negative radical. The phosphates of potassium, sodium and ammonium are water-soluble ; all other phosphates are insoluble in water. Ferric phosphate is soluble in solutions of citrates of potassium, sodium or ammonium, and the "phosphate of iron " of the Pharmacopoeia is a compound consisting of the water-soluble scaled residue obtained from a solution of ferric phosphate in solution of sodium citrate. The soluble phosphates may be produced by the action of phosphoric acid upon hydrates or carbonates, but all phosphates >66 CHEMISTRY. are generally prepared by double decomposition. Phosphates of calcium, iron and some other phosphates which are insoluble in water, dissolve in ortho-phosphoric acid. Hence phosphate of iron can be made by the action of phosphoric acid upon iron. The phosphoric acid of the Pharmacopoeia is ortho-phos- phoric acid. 915. The officinal phosphates are all contained in the follow- ing Table of Common Phosphates with their. Molecular Formulas and Molecular Weights: Names. Phosphates. Hydrogen (ortho-phos- phoric acid) Potassium Sodium " crvst. Microcosmic salt Ammonium Calcium Acid Manganous Ferrous Manganic Ferric Ferroso-ferric Formulas. H 3 P0 4 K 2 HPO ± Na 2 HPO, N^HPO^HjjO NH 4 NaHP0 4 . 4 H a O (NH 4 ) 2 HPO, Ca s (P0 4 ) 2 CaH 4 (PO,) a MnslPCg^H-jO Fe 3 (P0 4 ) 2 .8H 2 Mn 2 (P0 4 ) 2 . 4 H 2 Fe 2 (PO i ) 24 H 2 2Fe 3 (PO i ) 3 .Fe 2 (P0 4 ) 2 . 24 H 2 i Molecular i Weights. 98 174.2 1 4 2 358.1 4 i8 132 310 234 481 502 425.9 374 i45°- 2 CHEMISTRY. 267 916. Metaphosphates. — The so-called "glacial phosphoric acid " is meta-phosphoric acid more or less contaminated with pyrophosphoric acid and with phosphates, as found in com- merce. The relations of meta-phosphoric, ortho-phosphoric and pyro-phosphoric acid to each other are shown by these equations: 2HPO3 + H 2 = H 4 P 2 7 Meta-phosphoric acid Water Pyrophosphoric acid; and- H 4 P 2 7 + H 2 G = 2H 3 FO, Pyrophosphoric acid Water Orthophosphoric acid Metaphosphoric acid is changed to orthophosphoric acid by being boiled in water. Ferric metaphosphate and ferric pyrophosphate are insoluble in ortho-phosphoric acid, but soluble in metaphosphoric acid. Metaphosphoric acid is HPO s = 80. 917. Pyrophosphates contain the radical P 2 7 ,- which acts as a tetrad. Pyrophosphate of sodium is formed when phos- phate of sodium is heated strongly; but the pyrophosphate is not decomposed even at extremely high temperatures. Insoluble pyrophosphates are made by double decomposition from pyrophosphate of sodium. Crystallized sodium pyrophosphate is Na 4 P:0 7 ,ioH 2 = 446.1; dried sodium pyrophosphate is Na 4 P 3 : = 266; ferric pyrophos- phate is Fe 4 (P 2 7 ) 3 = 746. Ferric pyrophosphate is insoluble in water, but soluble in diluted metaphosphoric acid; it is also soluble in solutions of alkali citrates, and the pharmacopoeial "pyrophosphate of iron " is the water-soluble scaled residue obtained from a solution of ferric phosphate in solution of sodium citrate. 918. Hypophosphites contain the group HoPO^ which acts as a monad. The hypophosphites of potassium, sodium, cal- cium and iron are used as medicines; they are all water-soluble, except that the iron hypophosphites are so sparingly soluble as to be practically nearly insoluble. 268 CHEMISTRY. Calcium hypophosphite is produced by boiling phosphorus with calcium hydrate; the others are prepared from the calcium hypophosphite or from the sodium salt. The formulas and molecular weights of the officinal hypo- phosphites are: Hypophosphorous Acid = H H 2 P0 2 = 66. Potassium Hypophosphite = K H 2 P0 2 = 104. Sodium " = Na H. 2 PO.> = 106. Calcium " = Ca (H 2 P0 2 ) 2 = 170. Ferrous " = Fe (H 3 P0 2 ), = 186. Ferric " = Fe 2 (H 2 P0 2 ) 6 = 502. CHAPTER LII. CARBONATES, ETC. 919. Carbonates are the salts containing the group CO? which is bivalent. They are easily decomposed by acids, the gas C0 2 being given off with effervescence. The carbonates of the alkali metals are the only carbonates not decomposed by heat. Sodium carbonate and potassium carbonate are pro- duced in immense quantities by heating the sulphate with chalk and coal. Insoluble carbonates are prepared from the soluble carbonates by double decomposition. Acid carbonates are commonly called " bicarbonates." Mag- nesium, zinc and lead form "basic carbonates." CHEMISTRY. 269 O20. Table of Common Carbonates with their Molecular Formulas and Molecular Weights: Names. Formulas. Molecular Weights. Hydrogen (carbonic acid) H 2 CO s 62 Potassium, anhydrous K 2 CO s 138 " ordinary 2K 2 C0 3 . 3H 2 330 " acid KHCO3 100 Sodium, anhydous Na 2 C0 3 106 " dried Na 2 C0 3 .2H 2 142 " cryst. Na 2 COo ioH 2 286 11 acid NaHC0 3 84 Lithium Li 2 C0 3 74 Ammonium, normal (NH,),C0 3 96 " acid NH 4 HCO s 79 " officinal NH 4 HC0 3 . XH 4 XH 3 CO s (BiO) 2 C0 3 . H 2 0. CaC0 3 157 Bismuthyl 528 Calcium 100 Barium BaC0 3 197 Manganous MnCO s "5 Ferrous FeC0 3 . H 2 J 34 Magnesium 4 MgCO,. Mg(OH). • 5H 2 487-5 Zinc 2ZnCO s . 3Zn(OH). 548.5 Lead 2 PbCO-.Pb(OH)- 774-9 921. Borates. — Boric acid is H3BO3 = 62. No normal borates are used. Borax or " borate of sodium " is a pyro- borate^agBiOr.ioHaO = 382.1. Both boric acid and borax are water-soluble. 922. Silicates contain the radical 5i0 3 , which is analogous to C0 3 and of the same exchangeable value. The silicates of potassium and sodium are water-soluble; all others insoluble CITOnSTRY. dium silicate is called " water-glass.' Fir.: glass is silicates of lead of potassium; crown glass consists of silicates of sodium and calcium, and Bohemian glass chiefly >f silicates )f potassium and calcium . The formulas and molec- uiar -"'r:^:5 ::' :;.: z r;n:ic ?.'. siii:a:es are: ?::_ss:a~ Siliz^e = K ; = if-.; Sriiurn Silicate =Na*S.. = :::; Cai::a~ 5ili:a:e = CaSiO a =116.3 Lead Silicate = PbSiO, = 282.7 223. Arsenates have a structure analogous to that of the z b : s z hat es. Ort : - a r 5 e r. a : es contain the radical As G # which, like PO^ is trivaier.:. Sodium arsenate is an official prepara- ■.::n ir. : is v.-=:er-s: luizie : :::e :rys:a".l:iri. sziiarr. irser.^:e :s NaaHAsO^H^O = 312; the effloresced salt is \a : H I i .:H:G = :::: and the dried Xa>HAs0 4 = 186. Iron arsenate is sometimes used as a medicine; it is usually of the composition 2Fe 3 (As0 4 ) 2 .Fe 2 (As0 4 ) a .24H 2 = 1714-2. 924. Arsenites. — When arsenous oxide is dissolved in water the solution may be regarded as containing arsenous acid, H a AsQ,= 126. Arsenite of potassium is contained in "Fowler's Solution," the salt being K H A s 3 = 202. 2. 925 Pyro-arsenare A sodium is formed when sodium :r:a: -arsenate is s:r: zzz'.y heated: i: :s -viter-s : .-die ?.z.i it^s the formula (dried X^ = 368. 026. Permanganate ::' z :>tassium, which is so valuable as an oxidizing agent, has the formula Kji - =316 and is solu- ble in about 16 times its weight of water at ordinary room tem- r eratures :~~ Normal rzt^ssium chromate is X : ■'.__= 194 and the so-called " bichromate of potassium "is K ; = 294. CHEMISTRY. 271 CHAPTER LIII. METALLIC SALTS OF THE ORGANIC ACIDS. 928. Acetates are the salts formed by the acetate radical, I 1 which is univalent. All acetates are water-soluble, and • hey are generally made from acetic acid and the oxides, hydrates or carbonates of metals. Other _:±:-;e5 are made by double decomposition. 929. The Common Acetates with their Molecular Formulas and Moleculir Weights are: Na / rmulas ■S '.: : Acetates . Hydrogen Potassium Sodium " cryst Ammonium HC na KC H Na Na . ;H,0 NH 4 60 9 8 :: I3 6 Magnesium Zinc " cryst Mg(C H 1 Zn Zn .5H.O I 4 2 -3 183 : - Lead " basic Copper Pb . ;HX> Pb .PbiOH Cu(QH s O s ,K_ 578.4 199.2 Aluminum Ferric AU(OH 466 930. Valerates, or "valerianates," contain the radical . which is a monad. Those used in medicine and phar- macy are water-soluble. Valeric acid is = H Sodium Valerate is = Na Ammonium Valerate is = XH : 102 124 119 Zinc Valerate is = Zn .H : = 2S5 ; HIMISTRY Lactates contain the radical They are little 90 1 12 218 297 931- d sed. Lactic Acid = H; ; Sodium Lactate = XaC H Calcium Lactate = Ca Zinc Lactate = Zn ; ;H : Ferrous Lactate = Fe -sFFO 932. Oleates. — The oleate radical is .which is a monad. Fats, soaps, and lead plaster are the most familiar cieates. All oleates except the soaps are insoluble in water. Soft soap consists entirely or chiefly of potassium oleate: hard soaps contain almost exclusively sodium oleate; the oleates of lead, zinc, iron, copper, and other heavy metals are plasters. The liquid fats or fixed oils are mainly oleate of glyceryl. Oleic acid is made from fats, and all other oleates from either oleic acid or fats. 933. The Common Oleates are: A 2 ma Z.7.: Mercuric Cupric Lr£.l Bismuth Aluminum Ferric /.">■":-.'-.". Hydrogen (oleic acid) Potassium S Hum Silver Mercurous HC H k; h NaJ H A g ; h Zn Hg ; Cu P: O a ) 3 a: : : -o,)« Fe ; ; Molecular Weights. 282 3S9 962 627 762 625 769 «>5 174 179 CHEMISTRY. 273 934. Oxalates are salts of the oxalate radical . Oxalic acid is bibasic. The oxalates of potassium sodium and ammonium are water- soluble, and made by neutralizing oxalic acid with the alkal hydrates or carbonates; all other oxalates are insoluble and made by precipitation. Oxalic acid is probably the " strongest" of the organic acids. No oxalates, except the cerium and ferrous, are official, but several are officinal. Oxalic acid = H 2 . = 90 " with water = H, 2H0O = 126 Potassium oxalate, normal = K, 2H.O == 202 " acid = KH 2H 2 = 162 Ammonium (NHJgC ,H,0 = 142 Cerium ii Ce 2 , 9 H 8 0— 706 Ferrous .. Fe .H,0 = 162 935- Tartrates. — The tartrate radical is , and it acts as a dyad. Acid tartrate of potassium is contained in the juice of grapes and other fruits. In the crude, impure state the potassium acid tartrate is called "argols," or " crude tartar;" and the pure is called ''cream of tartar," or "bitartrate of potassium." All other tartrates are made from the acid tartrate of potassium, directly or indirectly. Acid tartrate of potassium is only sparingly soluble in water, requiring about 200 times its own weight of water at ordinary room temperatures; the acid tartrates of sodium and ammonium are also sparingly soluble. The acid tartrates form soluble compounds with iron, of which the official tartrate of iron and potassium and tartrate of iron and ammonium are examples. 2 74 CHEMISTRY, 936. The common tartrates are: Names. Formulas. Molecular Weights. Hydrogen (tartaric acid) Potassium, normal " acid H 8 QH 4 6 k 2 c :■ KH C 4 H,O 150 226 188 (cream of tartar) .Rochelle salt Sodium, normal " acid Ammonium, normal acid KNaC .HxO 4H 2 Na 2 C,H.G 2H 2 NaHC ; H.u H 2 (NH^QH.Oe NH 4 H C 4 H 4 O 282 230 190 184 16, Potassium Antimonyl ("Tartar Emetic ") 2X850 0^0,^0 664 Magnesium MgQH 4 6 172 937. Citrates are the salts formed by the radical C 6 H 5 0^ which is trivalent. There are, therefore, three kinds of citrates {897). Citric acid is contained in various fruit juices, espe- cially those of lemons, limes and currants. Other citrates are prepared from citric acid. The citrates are generally water- soluble. The water solutions of alkali citrates dissolve ferric phosphate, pyrophosphate and hypophosphite, all of which are insoluble in water. Bismuth citrate is soluble in ammonia water. 938. The most common citrates are: Names . Formulas. Moleculat Weights. Hydrogen (Citric Acid) Potassium, normal Di-Potassium Hydrogen Potassium Di-Hydrogen Sodium, normal h 3 : : .HoO K 3 GH,O 7 H 2 K 8 H C 6 H 5 7 KH a C 6 H 5 7 Na 3 CH 5 7 210 3 2 4 286 248 258 CHEMISTRY. 2 75 Names. Formulas. Molecular Weights. Di-Sodium Hydrogen Na 2 H QH 5 7 236 Sodium Di-Hydrogen NaH 2 QH 5 7 214 Ammonium, normal (NH 4 ) S C 6 H 5 7 243 Di-Ammonium Hydrogen (NH 4 ) 2 H C 6 H 6 7 226 Ammonium Di-Hydrogen NH 4 H 2 C 6 H 5 7 209 Lithium, normal Li 3 C 6 H 5 7 210 Magnesium, normal Mg 3 < C 6 H B 7 ) 2 450-9 " acid MgH C«H 6 7 214.3 Ferric Fe 2 (C c H 6 7 )*6H 2 598.1 " anhydrous Fe 8 (QH 5 7 ) 2 490 Bismuth Bi C 6 H 5 7 398 939. Phenolsulphonates are salts containing the complex radical C 6 H 5 SO, [Ortho-sulphonic acid is C 6 H 4 .OH.HS0 3 .] The phenolsulphonates used in medicine and pharmacy are com- monly called " sulphocarbolates." We have phenolsulphonates of— Sodium = NaC 6 H 5 SO t 2H 2 = 232 Calcium = Ca (C 6 H 5 S0 4 ) s = 386 Barium = Ba (C 6 H 5 SC) 4 ) 3 = 483 Zinc = Zn (QHsSOO^^O = 555 940. Salicylates contain the acid radical C7H 5 3 The salicylates used in medicine are all made from salicylic acid or from salicylate of sodium. Salicylic acid is made from phenol (commonly called "carbolic acid""). The volatile oil of winter- green contains 90 per cent, of methyl salicylate. The alkali salicylates are readily water-soluble, and salicylate of zinc moderately soluble, while salicylic acid is nearly insoluble. The common salicylates are: Salicylic Acid — H =138 Sodium Salicylate = 2Na 0»H 2 = 338 Lithium " = 2 LiC 7 H,0 3 H 2 = 306 Zinc " = Zn H 5 3 ), 3 H 2 = 393 Bismuth " = Bi(C 7 H 5 3 ) 3 = 620 276 CHEMISTRY. 941. Benzoates. — The acid-radical of the benzoates is C 7 H 5 2 . Benzoic acid occurs in benzoin, and is also produced synthetically from tolnol", etc. The benzoates of sodium, lithium and ammonium are used medicinally; they are all water- soluble and prepared from benzoic acid and the respective alkali carbonates. The formulas are : Benzoic acid HC 7 H 5 C = 122. Potassium Benzoate KC 7 H 5 2 = 160. Sodium " NaQH 5 ? H 2 = 162. Lithium " LiC 7 H 5 3 = 128. Ammonium " NH 4 C 7 H 6 2 = 139. Calcium " Ca(C 7 H 5 2 ) 2 = 282. Ferric " Fe 2 (C 7 H 5 2 ) 6 = 838. CHAPTER LIV HYDROCARBONS. 942. Hydrocarbons. — The hydrocarbons are compounds of only the two elements, carbon and hydrogen. Hundreds of them are already known, and numerous others are possible. The hydrocarbon molecules may contain any number of carbon atoms, from one up to at least thirty-five. In all hydrocarbons containing more than one carbon atom, all the carbon atoms present are, of course, united by a portion of their bonds into a continuous chain or ring, or cluster, while all of the hydrogen atoms are united to the remaining carbon bonds. 943. As carbon is a tetrad it follows that the highest propor- tion of hydrogen that can unite with carbon is present in the compound CH 4 , called methane (commonly called " marsh- gas"). 944. All hydrocarbons may be arranged into several differ- ent series, each series represented by one general formula, and CHEMISTRY. 277 the several members of each series differing from each other by the group CH 2 or a multiple of it. Such series are called homologous series. 945. The first series, or methane series, of hydrocarbons begins with the following members: H I 1 . H— C— H k H H I I 2. H— C — C— H I I H H H H H I I I 3. H— C — C — C— H . I I i H H H H H H H I I I I 4. H— C— C — C — C— H I I I I H H H H H H H H H I I I I I 5. H— C— C— C— C — C— H I I I I I H H H H H H H H H H H I I I .1 I I 6. H-C— C — C— C— C— C— H I I I I I I H H H H H H It will be seen that for every additional carbon atom there must be two additional hydrogen atoms. This explains why it is that each member of the series differs from the preceding member by CH 2 . 946. If you examine the formulas just presented you will find that this whole series may well be represented by the general formula: H(CH 2 )«H, for 278 CHEMISTRY. every member of the series consists of any number of groups of CH 2 linked together by their carbon bonds and the chain united to a hydrogen atom at each end. As commonly written the formulas are: CH 4 C 2 H 6 C 3 H 8 C 4 H 10 and so on. In another series the first number is: II H H I = C I H the second member H — C — C=C I I I H H H H H H I I I and the third member H — C — C — C=C I I I I H H H H For this the general formkila (CH 2 )« might be assigned. 947. But the general formulas for the homologous series of hydrocar- bons are usually expressed as follows: Series 1. CnW 2 n + 2 Lowest member known, CH 4 C 2 H 4 Co Ho C 8 H 8 C 8 H 6 C 10 H 8 C 14 H 12 Cl4"l0 Ci 7 H 14 Cl6H\ C22H14 ^26"20 In these general formulas the italic letter n means any number. Thus the general formula for Series I, written CnH 2 n + 2 means: any number of car- bon atoms united with twice the same number plus two of hydrogen atoms; 2. CnH 2 n 3. CnH 2 n- -2 4. CnH 2 n- "4 5. CnH 2 n- -6 6. C«H 8 «- -8 7- C«H 8 «- -10 8. CnH 2 n- -12 9- CnH 2 n- -14 10. C«H 2 ;z- -16 11. CnH. 2 n- -18 12. CnH 2 n- -20 13- CnH 2 n- -22 14. CnH 2 n- -24 15- CnH 2 n- -26 16. CnH 2 n- -28 17. C«H 2 «- -30 18. CnH 2 n- -32 CHEMISTRY. 279 the general formula for Series 2, written C«H 2 « means: any number of car- bon atoms united to twice the same number of hydrogen atoms; the general formula for Series 3, written C«H 2 « — 2 means: any number of carbon atoms united to twice the same number less 2 of hydrogen atoms; etc. 948. Knowing the number of carbon atoms in any member of any one of these series we can write its molecular formula in accordance with the gen- eral formula for its series; thus the member of Series 1 having 12 carbon atoms must be C 18 H 26 ; of Series 2 it would be C 12 H 24 ; of Series 3, C 12 H 22 ; of Series 4, C 12 H 20 ; of Series 5, 'C 12 H l8 ; of Series 9, C 12 H 10 ; of Series 14 there could be no member with but twelve carbon atoms, and of Series 10 to 13 none are known having twelve atoms of carbon. 949. Hydrocarbons are generally gaseous when containing less than four atoms of carbon; liquid if containing more than four but less than twelve carbon atoms; solid 'if they contain a higher number of atoms of carbon. 950. According to the properties of their derivatives, the hydrocarbons are divided into two series — the fatty series and the aromatic series. Fats or fixed oils belong to the derivatives of the fatty series of hydrocarbons, and the aromatic acids and other aromatic or odorous compounds are derivatives of the aromatic series. 951. Marsh gas, CH 4 , is a colorless and tasteless gas, which is generated in swamps by the decay of organic matter ; it is the principal constituent of the so-called " natural gas," and in coal mines it exists as " fire-damp." 952. Hydrocarbons occur in coal oils, paraffines, petrolatum, paraffin oil, illuminating gas, natural gas oil of turpentine, oil of lemon and many other volatile oils, etc. Among the common hydro-carbons are: Paraffin = C6H34. Benzin = C 5 Hi 2 and C 6 Hi 4 . Turpenes= (Ci Hifi)«. Benzene ■*- C 6 H 6 . 953. Among the derivatives or substitution products of hydro-carbons are: Chloroform, CHC1 3 , which is tri-chlor-methane. Iodoform, CHI 3 , which is tri-iodo-methane. The haloids of the hydro-carbon radicals correspond to the chlorides, bromides, iodides and cyanides of the metals. Thus, trichlormethane may be regarded as formyl chloride, or the chloride of the radical CH. Haloids of methyl (CH 2 ), ethyl (C 3 H 5 ) and other positive organic compound radicals (263) are well-known. 954. Hydrocarbon Radicals are groups of carbon and hydrogen atoms having free carbon bonds. 280 CHEMISTRY. When a hydrogen atom is removed from a hydro-carbon molecule, the remainder constitutes a positive radical with one valence unit; for every addi- tional hydrogen atom removed another valence unit is added to the radical. Thus, if we take one hydrogen atom from CH 4 , we have the radical CH 3 left, which is univalent; the removal of two hydrogen atoms would leave the rad- ical CH 2 with two free bonds: and if still another hydrogen atom be removed, we get the trivalent radical CH. 955. The hydrocarbons (942) may be regarded as the hydrides of the hydrocarbon radicals. Thus Methane, CH 4 , can be looked upon as the hydride of methyl. CH 3 H; ethane, C\H 6 . as ethyl hydride. C 2 H 5 H, etc. 956. Hydrocarbon radicals, in fact, form the same classes of compounds as are formed by metals, namely, oxides, sulphides, chlorides, bromides, iodides, cyanides, bases and salts. Their oxides are called ethers, their hydrates are alcohols, and the salts they form with the acids are called ethe real salts. CHAPTER LV. OTHER IMPORTANT CLASSES OF ORGANIC COMPOUNDS. 957. Alcohols. — The alcohols of organic chemistry cor- respond to the metallic hydrates of inorganic chemistry. They all contain hydroxyl, HO. which is united to the hydrocarbon radical just as the hydroxyl in a metallic hydrate or base is united to the metal. There are three classes of alcohols, namely, primary^ secondary and tertiary alcohols. 958. Primary alcohols all have the general formula H(CH 2 )n OH: that is. they ail contain the two groups, CH 2 and OH. When oxidized the primary alcohols yield first aldehydes, and then acids, containing the same number of carbon atoms. 959. Secondary alcohols all contain the two groups, CH and OH. When subjected to the action of oxidizing agents they form acetones: and, upon further oxidation, acids containing a smaller number of carbon atoms. CHEMISTRY. 281 960. Tertiary alcohols all contain C.OH. When oxidized they form neither aldehydes nor acetones, but are directly converted into acids having a smaller number of carbon atoms. 961. Any organic compound containing hydroxyl of which the hydrogen can be replaced by an acid-radical, is an alcohol. If this alcohol yields alde- hyde when oxidized, and then an acid, it is a primary alcohol; if its oxidation results in acetone and subsequently acid, it is a secondary alcohol; and if upon oxidation it splits up, yielding an acid without first forming an aldehyde or an acetone, it is a tertiary alcohol. 962. The simplest primary alcohol is methyl alcohol, CH 3 OH (commonly called wood alcohol, or wood spirit). If two of the hydrogen atoms of the group CH 3 in that alcohol be replaced by hydrocarbon radicals, the resulting products are secondary alcohols; if all three of the hydrogen atoms of the methyl group are replaced by hydrocarbon radicals, tertiary alcohols result. 963. It will be seen that the characteristic alcohol groups differ from each other by one or two hydrogen atoms, since Primary alconols contain CH. 2 OH Secondary " " CH.OH Tertiary " il C.OH 964. Alcohols containing but one hydroxyl group are sometimes called monatomic alcohols, while those containing two hydroxyl groups are called diatomic alcohols, and alcohols with three hydroxyl groups are called triatomic alcohols. A monatomic alcohol is, of course, the hydrate of a univalent hydro- carbon radical ; a diatomic alcohol is the hydrate of a bivalent hydrocarbon radical ; and trivalent hydrocarbon radicals must furnish triatomic alcohols 965. Among the alcohols the following are familiar: Methyl alcohol, or wood spirit = CH 3 OH. Ethyl alcohol, or ordinary alcohol = C 2 H :) OH. Amyl alcohol, or fusel oil = CJI^OH. Phenyl alcohol, or "carbolic acid " = C H 5 OH. Glyceryl alcohol, or "glycerin" = QH 5 (OH) 3 . Ethyl alcohol is formed by the fermentation of glucose ( 1 102) : C 6 H 12 O c = 2C 2 H 5 OH + 2 C0 2 Glucose Alcohol Carbon dioxide 282 CHEMISTRY. 966 Mercaptans are compounds analogous to the alcohols in general structure, but containing HS instead of HO. They are, then, hydrosulphides of hydrocarbon radicals. 967. Aldehydes. — When primary alcohols are oxidized in a limited supply of oxygen they are transformed into aldehydes by the removal of hydrogen. The name is coined out of the words 3 = Propyl H(CH 2 ) 4 = Butyl H(CH 2 ) 5 = Amyl H(CH 2 ) 6 = Hexyl etc. Hydrocarbons: — Ethers. Alcohols: — Aldehydes. HCH 2 H = Methane H(CH 2 ) 2 H = Ethane H(CH 2 ) 3 H = Propane H(CH 2 ) 4 H = Butane H(CH 2 ) 5 H = Pentane H(CH 3 ) 6 H = Hexane etc. HCE = Methyl Oxide HCH 2 / H(8HU0°= PrOpylOxide ]^H 2 ) 4 \ 0== Butyl Oxide SinS 3 wO= Pentyl Oxide etc. HCH 2 OH = Methyl alcohol H(CH 2 ) 2 OH = Ethyl alcohol H(CH 2 ) 3 OH = Propyl alcohol H(CH 2 ) 4 OH = Butyl alcohol H(CH 2 ) 5 OH = Amyl alcohol etc. H.CO.H = Formic aldehyde H.CH 2 .CO.H = Common aldehyde CHEMISTRY. 287 Acetones:^ Acids: — H.(CH 2 ) 2 .CO.H = Propyl aldehyde H.(CH 2 ) 3 .CO.H. = Butyl aldehyde H.(CH 2 ) 4 .CO.H. = Amyl aldehyde etc. H.CO.CH 2 .H H.CH 2 .CO.CH 2 H. H.(CH 2 ) 2 .CO.CH 2 .H. H.(CH 2 ) 3 .CO.CH 2 .H. or — HCH 2 HCH/ H(CH 2 ) 2 - H(CH a ) r H(CH 2 ) 3 \ rn H(CH 2 ) 3 / LU ' CO CO H.CO.OH. = Formic acid H.CH 2 .CO.OH = Acetic acid H(CH 2 ) 2 .CO.OH = Propionic acid H(CH 2 ),CO.OH = Butyric acid H^CH^.CO.OH = Valeric acid etc. 976. Carbohydrates are compounds containing carbon, hydrogen and oxygen, and no other elements, the carbon atoms being six in number or a multiple of six, while the hydrogen atoms present are twice as many as the oxygen atoms present. The word "carbohydrate" is based upon the general constitution just described, which suggested to the originator of the term carbohydrate that these substances might be likened to hydrates of carbon. The formula C 6 Hi O 5 looks like six atoms of carbon and five molecules of water, C^H^On looks like twelve carbon atoms and eleven molecules of water, and hydrates were formerly considered as compounds containing water. But the hydro- gen and oxygen in carbohydrates are not combined into water molecules, nor can carbon combine with water, so that the name is confusing. 28S CHEMISTRY The principal classes of carbohydrates are as follows : Cellulose Group Saccharose Group Glucose Group (C 6 H 10 O 5 ) n Ci.3H2.2On C 6 H 12 6 Cellulose Cane Sugar Grape Sugar Starch Milk Sugar Fruit Sugar Dextrin Maltose Gums Melitose 977- Glucosides are complex bodies, sometimes having weak acid properties, sometimes neutral, which are split up under the influence of dilute acids, ferments, etc., especially with the aid of heat, yielding, as one of the decomposition products, sugar of the glucose group. Many of the neutral principles of plants are glucosides. Salicin, santonin, and amygdalin are examples of glucosides. 978. Alkaloids are organic compounds resembling am- monia in that they contain nitrogen, have an alkaline reaction on test-paper, and are capable of neutralizing acids with which they combine to form salts. The chemical structure of alkaloids is not yet clearly understood. Alkaloids occur in many plants of decided medicinal potency. Most of them are so powerful in their effects upon the animal organism as to be poisonous, but some of the alkaloids appear to be simply bitter tonics. Among the common alkaloids are quinine, morphine, strychnine, veratrine, atropine, eodeine, caffeine, cocaine. By far the greater number of the alkaloids are solids, inodor- ous, bitter or acrid, non-volatile, and contain in their molecule carbon, hydrogen and oxygen as well as nitrogen. These are called amides, or quaternary alkaloids. Other alkaloids contain only carbon, nydrogen and nitrogen, these are called amines, or ternary alkaloids, and are liquid, vola- tile, and strongly odorous. The only common volatile alkaloids are nicotine, which is contained in tobacco; coniine, in conium ; and lobeline, in lobelia. When alkaloids combine with acids to form salts they behave exactly as ammonia does in that they unite with the whole acid- molecule, including its hydrogen, thus : CHEMISTRY. 289 NH 3 + HNO3 = NH 4 N0 3 Ammonia, Nitric Acid, Ammonium Nitrate, NH 3 + HC1 = NH 4 C1 Ammonia, Hydrochloric Acid, Ammonium Chloride, NH 2 CH 3 + " HNO3 = NH 2 CH 3 HN0 3 Methylamine, Nitric Acid, Methylamine Nitrate, 2 C 21 H 22 N 2 2 4- H 2 SO, = (C 21 H 22 N 2 2 ) 2 H 2 S0 4 Strychnine, Sulphuric Acid, Strychnine Sulphate, C 20 H 24 N 2 O 2 + HC1 = C 20 H 24 N 2 O 2 HCl Quinine, Hydrochloric Acid, Quinine Hydrochlorate. CHAPTER LVI. CHEMICAL NOMENCLATURE. 979. The names of chemical compounds are generally con- structed out of the names of the constituent radicals so far as practicable. When, however, the molecule is complex and sev- eral different molecules contain the same elements that plan is impracticable, and the technical names given to such com- pounds are based upon their internal structure, source, or prop- erties, or upon other facts or conditions. Some names in com- mon use are entirely arbitrary and unscientific, and have mostly been transmitted from early times. The technical names of chemicals usually consist of two parts. 980. Whenever the name of a chemical compound is derived from the radicals which enter into it, then the first part of the name is derived from or consists of the name of the posi- tive radical, while the second part is derived from the negative radical. * Thus we say silver oxide, potassium chloride, mercuric iodide, sulphur dioxide, calcium sulphide, copper nitrate, ethyl nitrite, magnesium sulphate, magnesium sulphite, etc. 290 CHEMISTRY. 981. Binary compounds (844) and many other compounds consisting of two radicals directly united have generic names ending with -ide and derived from their respective negative radicals. Thus compounds consisting of positive radicals (elemental or compound) directly united to oxygen are called oxides; when the positive radical is united to sulphur the compound is called a sulphide, etc. If we designate the posi- tive radical by the letter -t- R, then + 4- RO=oxide. RH^hydride. + + RS=sulphide. RP=phosphide. + + RCl=chloride. RSe=selenide. RI=iodide. RCH 3 =methylide. + + RBr=bromide. RN=nitride, etc. RCN=cyanide. 982. But it often happens that two or more different com- pounds are formed by the same two radicals. There are five different oxides of nitrogen ; five oxides of manganese ; four oxides of chlorine ; three sulphides of arsenic ; two chlorides of iron or of mercury, etc. [The fact that any two radicals may form more than one compound by combining in more than one proportion is explained on the assumption that many of the elements have a variable valence, as explained elsewhere. Some- times this assumption seems unnecessary, as in the case of the oxides of nitrogen and chlorine, which may be represented by chains : N — O — N, N— O— O— N, CI— O— CI, CI— O—O— O— CI. etc.; but in other cases no explanation seems possible except that afforded by the assumption of variable valence (617 to 619).] 983. Different names must, of course, be given to these different compounds in order to distinguish them from each other. The simplest method, and, therefore, the best, is to pre- fix the Greek numerals to the second part of the name, to indi- cate the number of times the negative radical is multiplied. CHEMISTRY. 291 The oxides of nitrogen all contain two atoms of nitrogen and 1, 2, 3, 4 or 5 atoms of oxygen. They are, accordingly, represented by the following names and formulas : Nitrogen monoxide, N 2 0. Nitrogen dioxide, N 2 2 . Nitrogen trioxide, N 2 3 . Nitrogen tetroxide, N^O^. Nitrogen pentoxide, N 2 5 . This system is very explicit, and might advantageously be employed to a greater extent than it is. 984. In some cases, however, this method of numeral pre- fixes (983) in connection with the negative radicals is not appli- cable as, for instance, in compounds of mercury which contain the same number of atoms of the negative element but differ- ent numbers of atoms of the positive element. 985. A still more explicit method is to prefix numerals to both of the radicals. Thus we might say di-nitrogen mon- oxide, di-nitrogen di-oxide, di-nitrogen tri-oxide, etc. But this would seem to be superfluous in the naming of the nitrogen oxides, because all of them contain two nitrogen atoms. 986. In naming certain compounds of polyvalent radicals the use of numerals as prefixes is the most convenient as well as explicit method. Thus we would distinguish normal sodium phosphate Xa 3 P0 4 , from Na 2 HP0 4 and NaH 2 P0 4 as follows: r\a 3 PO i = tri-sodium phosphate, or normal sodium phosphate. r\ T a 2 HPO i = di-sodium hydrogen phosphate. NaHoPOi = sodium di-hydrogen phosphate. In a similar manner we might call water di-hydrogen monoxide, and the so-called peroxide of hydrogen. H 2 2 , might be called di-hydrogen dioxide. NH 2 CH 3 is mono-methyl amine; NH(CH 3 ) 2 is di-methyl amine; and N(CH 3 )3 is tri-methyl amine. In organic chemistry the use of numeral prefixes is invaluable, as may be seen in the following: Ethylene diamine = C 3 H 4 (NH 2 ) 3 Diethylene diamine = X 3 (C 2 H 4 ) 2 H 3 Triethylene diamine = N 2 (C 2 H 4 ) 3 Diethylene triamine = N 3 (C 2 H 4 ) 3 H5 Triethylene triamine = N 3 (C 2 H 4 ) 3 H 3 Triethylene tetramine == N*(C 3 H 4 ) 3 H 8 292 CHEMISTRY. 987. The numeral prefixes of Greek origin are: mono-, or mon-, meaning one or single. di- or dis-, " two or twice. tri- or tris-, " three or thrice. tetra-, " four. penta-, " five. hex a-, " six. hepta-, " seven. octo-y " eight. ennea-, " nine. deka-, " ten » 988. The numeral prefixes of latin origin are: ten-, or uni- = one or single duo-, or £z'-, or bis-, = two or twice ter-, or /n, = three or thrice quadri-, or quadra- = four quinque-, or quinqui = five sexa— or sexi— = six hepta-, = seven tfffo- = eight non-, or nona-, or noni- = nine dec a— or deci— = ten 989. The oxides of chlorine might well be named in the same manner as the oxides of nitrogen, but they are usually- named as follows: Hyp ochlor ous oxide C1 2 Chlon?&.? Oxide C1 2 3 ChlonV Oxide C1 2 5 Perchloric Oxide O2O7 These names show the use of two terminal syllables, -ous and -ic, which are very frequently employed, and nearly always used when only two compounds containing the same elements are to be distinguished from each other. There are also two prefixes, hypo- and per-, in the foregoing names of the oxides of chlorine. These and some other prefixes commonly employed in chemical nomenclature will now be explained together with the meaning of the terminations -ic and -ous. 990. The endings, -ic and -ous, give an adjective form to the nouns to which they are affixed. Thus the noun argentum, CHEMISTRY. 293 meaning silver, is turned into the adjectives argentic and argen- tous; the noun ferrum, meaning iron, is transformed into the adjectives ferric and ferrous; the word mercury into mercuric and mercurous; antimony into antimonic and antimonous; arsenic (or arsenum) into arsenic and arsenous; sulphur into sulphuric and sulphurous, etc. Lexicographically the adjectives argentous and argentic both mean sil- vern, mercuric and mercurous both mean mercurial, antimonic and antimon- ous both mean antimonial, arsenous and arsenic mean arsenical, and ferrous and ferric are adjectives which stand for and mean the same as the word iron in the expression iron mortar. But a Latin adjective with the termina- tion -ous differs in degree from one with the ending -ic. Thus argentous means more silvern than argentic; a ferrouscompound means one containing a greater proportion of iron than is contained in a ferric compound; mercur- ous chloride contains relatively more mercury than mercuric chloride does; arsenous oxide contains a greater percentage of arsenic, or, which is the same, a smaller percentage of oxygen, than the arsenic oxide contains; etc. Therefore, when any two compounds, both consisting of the same two radicals, are to be distinguished by different titles the one containing the greater proportion of the positive radical or lesser proportion of the negative radical is called an -ous com- pound; and the other, which contains the greater proportion of the negative radical, or the lesser proportion of the positive radi- cal, receives the name of an -ic compound. Of the two chlor- ides of iron the higher chloride, containing proportionately more chlorine, is called ferric chloride, while the lower chloride, con- taining less chlorine in proportion to iron than the other, is ferrous chloride. A higher oxide is an -ic oxide, and a lower oxide is an -ous oxide. 991. The endings -ic and -ous are sufficient to distinguish two different compounds of the same two radicals, provided there are not more than two such compounds. As there are only two chlorides of iron, it is sufficient to call one the ferrous chlor- ide, and the other the ferric chloride. But when more than two different compounds are formed by the same two radicals, the terminations -ic and -ous are not only insufficient, but often mis- applied, or even confusing. 294 CHEMISTRY. 992. The additional prefixes, other than numerals, which have been employed in chemical nomenclature, are: Super- and hyper-, meaning above, over, in excess. per-, meaning thorough, to the full extent, through. sesqui-, half-as-much more, or one and one-half. sub- and hypo-, under or below. proto-, first or lower. multi-, ox poly-, many. ortho-, straight, regular, normal, original. meta-, beyond, after, derived from, deviating, altered, different. pyro-, as produced by fire or high heat. para-, beside, beyond, different, changed. Thus, super-oxide means a higher oxide; hyper-manganic acid or per- manganic acid means that acid of manganese which contains the greater pro- portion of oxygen; per-chloride of iron means the chloride of iron which con- tains the greatest possible proportion of chlorine with which iron can combine; sesqui-chloride of iron (which is the same as the per-chloride and ferric chloride) means a chloride of iron containing one and one-half times as much chlorine as the lower chloride contains; sub-chloride of mercury is the lower chloride of mercury, or calomel, or mercurous chloride, while per-chloride of mercury is the higher or mercuric chloride; hypochlorous oxide is a lower oxide than the chlorous oxide, and perchloric oxide is a higher oxide of chlorine than the chloric oxide, while chloric oxide is a higher oxide than chlorous oxide; ortho- phosphoric acid means the ordinary phosphoric acid, but meta-phosphoric acid is a different phosphoric acid derived from the ortho-phosphoric acid by the subtraction of one molecule of water (H3PO4 — H 2 0=HP0 3 ), and pyro- phosphates are formed when either meta-phosphates or orthophosphates are strongly heated; arabin is the acacia gum, but metarabin is a modified gum formed when acacia is subjected to heat; aldehyde has the formula C 2 H 4 0, and paraldehyde which has different properties is (C 2 H 4 0) 3 , but the difference between them arises from the internal structure. 993. Nomenclature of Acids. — Whenever any element forms more than one acid-forming oxide, and accordingly has more than one acid, the different acids are distinguished from ach other by names analogous to those given to the respective oxides. Thus, the acid formed by an -ous oxide is called an -ous acid; the acid formed by an -ic oxide is called an -ic acid; a hypo— ous oxide forms a hypo-ous acid, a per-ic oxide forms a per-ic acid, etc. CHEMISTRY ; 95 Hypochlorous oxide forms hypochlorous acid, chlorous oxide forms chlorous acid, chloric oxide forms chloric acid, perchloric oxide forms per- chloric acid, sulphurous oxide forms sulphurous acid, and sulphuric oxide forms sulphuric acid. 994. Nomenclature of Salts. — The salts formed by -ic acids are named after the acid by changing the terminal sylla- ble of the adjective to -ate, which at the same time converts the adjective into a substantive noun. Thus nitric acid gives nitrates, sulphates are the salts of sulphur/V acid, carbonates are formed by carbomV acid, etc. Salts formed by -ous acids have names ending with -ite instead of -ate. Thus hypophosphor^/j- acid forms hypophos- phitcs, nitn^i- acid forms nitrites, sulphur^.*- acid sulphites, and hypochlorous acid Aypochlorites. 995. Other characteristic terminal syllables.— The names given to compound radicals generally end in -yl, as methyl ethyl, butyl, amyl, bis- muthyl, nitrosyl, carbonyl, hydroxyl, phenyl, etc. Names of alcohols sometimes end with -ol, as in carbinol, phenol, cresol, thymol, etc. ; but the same ending is unfortunately also used in the names of other compounds, as in benzol, toluol, etc. Aldehydes and their derivatives are sometimes given names ending with -al, as in chloral. The terminal -ane appears in the names of hydrocarbons of the methane series, as in methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, etc. In the names of other hydrocarbons and their derivatives the terminal -ate is often used, as in benzene, toluene, xylene, naphthalene., anthracene, etc. In the names of alkaloids the ending -ine is used, as in strychnine, aconitine, belladonnine, hyoscyamine, emetine, etc. Simple derivatives of ammonia, not containing oxygen, have names ending with the word amine, as methyl-amine, ethyl-amine, propyl-amine, phenyl-amine, etc. Glucosides and other neutral principles have names ending with -in, as in salicin, populin, aloin, saponin, etc. Sugars receive technical names ending in -ose, as in sucrose or saccha- rose, glucose, laevulose, maltose, melitose, mannitose, etc. But other carbo- hydrates also have received similarly constructed names, as, for instance, cellulose, which is not a sugar, but is the matter of which cotton, linen, and the walls of vegetable cells consist. 296 CHEMISTRY CHAPTER LVII. LAWS GOVERNING THE DIRECTION AND COMPLETENESS OF CHEMICAL REACTIONS. 996. The course or direction which a chemical reaction may take is governed by various forces, among which the most important are electro-chemical polarity, and the solubility or non-solubility and state of aggregation of one or more of the products. 997. Malaguti's Law. — In double decompositions between substances in a state of solution ''the most energetic acid tends to combine with the most powerful base." We may put this law more comprehensively and correctly in the following form: All che?nical reactions tend to the utiion of the strongest positive with the strongest negative radical present. To illustrate its application we will enumerate a few of the most important positive and negative radicals, respectively, in the order of their electro-chemical energy or position, and use the compounds produced by these radicals to show r how the law operates. Positive radicals. Potassium Sodium Calcium Magnesium Iron Copper Mercury Hydrogen Negative radicals. K Sulphate radical so 4 Na Nitrate X0 3 Ca Chloride " CI Mg Bromide " Br Fe Iodide I Cu Tartrate C 4 H 4 € Hg Acetate C0H3O2 H Carbonate " C0 3 In the preceding table potassium is the most powerful of all the positive radicals enumerated, then sodium, next calcium, etc., dowm to hydrogen, which is a weaker electro-positive radical than any of the others. Of the negative radicals the sulphate radical is the strongest, and of the others included in this table, CHEMISTRY. 297 the nitrate radical stands next to the sulphate radical, the chlo- rine, bromine, iodine, etc., down to the carbonate radical, which is the weakest of them all. Now, according to Malaguti's law, sulphuric acid (which is hydrogen sulphate, HaSOJ must decompose all nitrates, chlo- rides, bromides, iodides, tartrates, acetates, and carbonates. Nitric acid (which is hydrogen nitrate, HXO s ) must decompose all chlorides, bromides, iodides, tartrates, acetates, and carbon- ates. Hydrochloric acid (which is hydrogen chloride, HC1) must decompose all bromides, iodides, tartrates, acetates and carbonates, etc. Potassium must displace sodium, calcium, magnesium, iron, copper, mercury and hydrogen from their compounds. Iron must take the place of copper, and copper in turn can usurp the place of mercury. Potassium being a stronger positive radical than copper, and the acetate radical being a weaker negative radical than the nitrate radical, if we mix a solution of potassium acetate with a solution of copper nitrate, there must be a reaction, resulting in the formation of potassium nitrate and copper acetate, for the reaction tends to the union of the strongest positive radical (potassium) with the strongest negative radical (the nitrate radical). In the same way and for the same reason we would get the following reactions: 2KNO s +MgS0 4 =4K 8 S0 4 +Mg(NO s ) a 6KC 2 H 3 2 +Fe 2 Cl 6 = 6KCl+Fe 2 (C 2 H 3 2 ) c Ca(C 2 H 3 2 ) 2 +MgBr 2 = CaBr 2 +Mg(C 2 H 3 2 ) 2 2KBr+FeS0 1 = K 2 SO.+ FeBr, Mg(C 2 H 3 2 ) 2 +Pb(N0 3 ) 2 = Pb(C 2 H 3 2 ) 2 +Mg(X0 3 ) 3 Na 2 C0 3 +2HCl = 2NaCl+C0 2 + H 2 Malaguti's law, as stated and illustrated above, holds good at ordinary temperatures if the products of the reaction are both soluble salts; but the reactions are not complete (998). 998. Berthollet's investigations prove that the operation of Malaguti's law (997) is greatly modified by the relative masses of the factors of the reaction, and by the relative solubilities 298 CHEMISTRY. of the possible products, and it has been observed that a reaction in accordance with Malaguti's law is never quite com- plete unless one of the products of the reaction is either a volatile or an insoluble compound (999). Thus, while, in obedi- ence to Malaguti's law, a solution of potassium chloride mixed with a solution of copper sulphate should produce potassium sulphate and copper chloride — CuSO,+ 2KCl = K 2 S0 4 +CuCl 2 the resulting liquid will in reality contain all of the four salts named; a mixture made of sulphuric acid with a solution of sodium nitrate will contain sodium sulphate, sodium nitrate, sul- phuric acid, and nitric acid; and a mixture made of a solution of magnesium sulphate with a solution of potassium tartrate will contain potassium sulphate, magnesium sulphate, potassium tartrate and magnesium tartrate. These are the results obtained when the proportions of the compounds mixed are the proportions required by theory for complete double decomposition according to the equations representing the reactions which should ensue according to Malaguti's law. But although the reactions which take place in accordance with this law do not progress to completion, the tendency of the reaction is unmistakable, and it is simply obstructed by physical conditions. Reactions, incomplete though they be, may thus take place between salts in a state of solution without any outward sign if the factors and products of the reaction are colorless as well as soluble. 999. Berthollet's Law of the Formation of Insoluble Compounds. — If any two of the radicals taking part in a chemical reactio?i between salts in solution would produce an insoluble compound if united to each other, then these radicals will unite. In other words, "when we cause two salts to react by means of a solvent, if, in the course of double decomposition, a new salt can be produced which is less soluble than those we have mixed, then that new and less soluble salt will be formed." CHEMISTRY. 299 Or, whenever, in any double decomposition between compounds in solution, an insoluble product is possible, theti that insoluble product will inevitably be formed. This law is general in its operation ; it produces complete reactions in the direction which it indicates, and it nullifies Malaguti's law in all cases where the two laws are in opposition to each other. A knowledge of the relative solubilities of chemical com- pounds, therefore, enables us to predict with certainty the direc- tion of the reaction in all cases where the factors of the reaction furnish the radicals required for the formation of insoluble products, and it also enables us to devise methods for the prep- aration of numerous substances. Knowing that lead iodide is insoluble, we also know that it must be formed whenever a solution of any soluble lead salt is mixed with the solu- tion of any soluble iodide. Knowing that lead iodide is a yellow insoluble solid, we know that we can not mix a solution of lead acetate or lead nitrate with a solution of potassium iodide, sodium iodide, or of the iodide of either ammonium, calcium, magnesium, zinc, or iron, without getting a yellow pre- cipitate. A solution of any one of the soluble salts of any of the heavy metals can not be mixed with a solution of any soluble hydrate, or carbonate, or phos- phate, without producing a precipitate, for, as we know, the hydrates, carbon- ates and phosphates of the heavy metals are all insoluble. Salicylate of quinine being insoluble in water we know that it would be impossible to mix an aqueous solution of hydrochlorate of quinine with a solution of sodium salicylate without getting a precipitate of quinine salicylate; but if enough alcohol is present, in which the quinine salicylate is soluble, no precipitate of that compound will be obtained, although quinine salicylate is of course formed in accordance with Malaguti's law, but we might expect instead (if enough alcohol is present) a precipitate of sodium chloride, which, although soluble in water, is not soluble in a liquid containing a considerable amount of alcohol. Most of the chemical incompatibilities met with in making extempora- neous liquid preparations arise from the formation of insoluble compounds. Hence the great importance of knowing the relative solubilities of chemicals. Common water, containing carbonates, chlorides, and sulphates, will not make clear solutions of the water-soluble salts of silver, lead, mercury, etc., because the carbonates, chlorides or sulphates of these and some other metals and bases are insoluble. 300 CHEMISTRY. iooo. Berthollet's law of the formation of volatile products. — When dry heat is applied to a mixture of two compounds, if any volatile product can be formed by double decomposition, then that volatile product will be formed. Thus when ammonium chloride and calcium oxide are heated together, the products calcium chloride, ammonia and water are formed; when a mix- ture of mercuric sulphate and sodium chloride is heated, mercuric chloride sublimes and sodium sulphate remains. It may be said in addition that compounds which may be split up into two or more other compounds, of which one is volatile, are comparatively unstable and may be decomposed either by heat alone, or by double decomposition aided by heat, or even by double decomposition without the aid of heat. In -other words, simple decomposition or double decomposition takes place, as a rule, more readily when one or more of the products of the reaction are volatile than when no volatile products are formed. Thus carbonates are comparatively unstable; they are easily decomposed by even weak acids, find are split up by high heat. The student should here refer again to the action of heat upon salts (533). 1001. Whenever a chemical reaction ensues in accordance w T ith the law of Malaguti (997), it progresses to completion pro- vided one of the two products is gaseous, as in the decomposi- tion of carbonates, sulphites, etc., by stronger acids. 1002. It will now be readily understood by the student that the synthetical and analytical reactions applied in the produc- tion of chemical compounds and in analytical work are based chiefly upon the laws of Malaguti and Berthollet which have just been presented and to which indirect reference has been made also in the preceding pages. CHEMISTRY. 3OI CHAPTER LVIII. OXIDATION AND REDUCTION. 1003. Oxidation. — To induce any metal or other element, or any compound, to take up or unite with oxygen is to oxidize that element or compound. Zinc oxide may be made by heating the metal strongly in free access of air. Combustion in oxygen or air, whether slow or rapid, is oxidation. To cause a lower oxide to take up more oxygen so as to form a higher oxide and to con- vert an -oics acid into an -ic acid, or an -ous salt into an -ic salt must also be called oxidation. Thus when an arsenite is con- verted into an arsenate, a sulphite into a sulphate, or phosphorous acid into phosphoric acid, or nitrogen dioxide into nitrogen tetroxide, oxidation takes place. 1004. But the direct union of oxygen with an element, or the addition of oxygen to any compound, or the introduction of oxygen into a molecule, is not the only methods of oxidation possible. The proportion of oxygen in a molecule may be indirectly increased by removing some other element. When alcohol, C 2 H 5 OH, is changed to alde- hyde, C2H4O, this change is really effected by oxidation because two atoms of the hydrogen of the alcohol are oxidized to water and thereby removed from the C 2 H 5 OH, leaving C 2 H 4 0, which at the same time contains a greater proportion of oxygen than is contained in the alcohol, for alcohol contains 16 parts of oxygen in 30, while the aldehyde contains 16 parts in 28. 1005. When the ferrous sulphate is converted into ferric- sulphate by means of nitric acid, it is the hydrogen of the sul- phuric and nitric acids used that is oxidized to water at the expense of the nitrate radical, thus: 6FeS0 4 +3H 2 S0 4 +2HN0 3 = 3Fe 2 (S0 4 ) 3 +N 2 2 + 4 H 2 0, and when ferrous chloride is converted into ferric chloride with hydrochloric and nitric acids the hydrogen of the acids is oxidized to water, while the chlorine from the hydrochloric acid raises the ferrous chloride to ferric: 6FeCl 8 +6HCl.+.2HN0 3 — 3Fe 2 Cl 6 +N 2 2 + 4 H 2 0. Both reactions are instances of oxidation. The following reaction is also an example of oxidation: As 2 3 -+-2NaN0 3 H-Na 2 C0 3 =Na,As 2 7 +N 2 3 +C0 2 . 302 CHEMISTRY. Nitric acid is also decomposed by organic substances, the molecule oi nitric acid being split up into the two radicals, N0 2 and HO, of which it is composed, and the group NO a is thus made to en:er into the organic molecule, where it replaces one atom of hydrogen, this hydrogen uniting with the hydroxyl to form water, as when cotton is converted into gun-cotton: C 12 H 2 o0 10 +6HN0 3 — C 12 H 14 4 (O.N0 2 ) 6 +6H 2 0. 1006. The oxidizing agents are either oxygen itself or some oxygen compound which readily gives up all or a portion of its oxygen, such as nitric acid and other nitrates, chromic anhydride, potassium permanganate, potassium chlorate, man- ganese dioxide, etc. 1007. Chlorine and the other halogens may act as indirect oxidizing agents in organic chemistry by removing hydrogen from the organic com- pounds; or, still more indirectly, by first introducing chlorine in the place of the hydrogen of the molecule, and subsequent introduction of hydroxyl to take the place of the chlorine, which can be effected with some metallic hydrate. 1008. Reduction is the opposite of oxidation. It is the removal of oxygen from a molecule, or the diminution of its proportion by the introduction of other elements into the same molecule, or the replacement of a portion or all of the oxygen by some other radical. The reduction of oxides to metals is sometimes easily accomplished by heat alone, as in the case of the oxides of silver, mercury and gold. 1009. Reducing Agents are substances having a strong affinity for oxygen, either at ordinary temperatures or when ■strongly heated with the oxygen compound. Carbon and hydrogen are often employed as reducing agents. Thus, iron ore is reduced to metallic iron by smelting it down in a furnace with charcoal, and " reduced iron " of the Pharmacopoeia is made by passing a current of hydrogen over oxide of iron heated to redness. Sulphurous acid and other sulphites are also sometimes used as effective reducing agents. Less effective reducing agents are glycerin, alcohol, sugar, tannin, and many other organic substances. CHEMISTRY. 303 CHAPTER LIX. NEUTRALIZATION. 1010. Soluble normal salts are most frequently prepared by- neutralizing the proper acids by the proper bases, or by metals, oxides, or carbonates. Thus any soluble sulphate may be pro- duced by neutralizing sulphuric acid, any acetate by neutralizing acetic acid, etc., by the requisite metal, oxide, base or carbonate. 1011. Test papers. — Litmus is a blue coloring matter made from certain lichens. Acids turn it red. Alkalies restore the blue color. When suitable unsized paper, like thin, white filter paper, is dipped in a weak solution of litmus and then dried it forms what is called "test paper." The solution of litmus used for this purpose is made with weak alcohol, and when used without the addition of acid it forms blue litmus paper, which is turned red by acids, by certain acid salts, and by some normal salts in which the acid radical is a powerful one while the positive radical is "comparatively weak. If the litmus tincture is treated with a little diluted hydrochloric acid so that its blue color is just changed to red, then paper dipped in this liquid and dried constitutes red litmus paper, which is turned blue by soluble bases and by some salts of strong bases with weak acids. The litmus solution or tincture may be made of one ounce powdered litmus to ten fluidounces diluted alcohol; macerate for a day, shaking occa- sionally, and then filter. 1012. Whenever it is stated in the Parmacopceia or in any other book that any certain substance has "an acid reaction on test paper," or that it exhibits an acid reaction, the statement means that the substance turns blue litmus red; whenever a substance is said to give a?i alkaline reaction, this means that it turns red litmus blue; and when a liquid or substance has a neutral reaction it does not change either the blue or the red litmus paper. Remember that acids turn blue litmus red, that alkalies turn red litmus blue, and that neutral salts do not effect litmus paper at all. Certain other blue vegetable colors are affected by acids and alkalies in precisely the same way as litmus. 1013. When a strong acid and a strong base neutralize each other the normal salt formed has a neutral reaction on test paper. 304 CHEMISTRY. Thus, if you put 200 grains of diluted acetic acid in a beaker, or in a graduate, and then add ammonia water, a little at a time, until the liquid no longer turns blue litmus paper red, but not so long that the liquid will turn red litmus blue — in other words, until the reaction is neutral — you will find that you have used just 34 grains of water of ammonia ; the diluted acetic acid turns blue litmus paper red, and the ammonia water turns red litmus paper blue ; but if you mix exactly 200 grains of strictly pharma- copceial diluted acetic acid with exactly 34 grains of water of ammonia of precisely the strength prescribed by the Pharmacoposia, you will find that the resulting liquid has a neutral reaction. If, however, the acetic acid is too weak the reaction will be alkaline, and if the ammonia is too weak the reac- tion will be acid. In making the solution of acetate of ammonium according to the Phar- macopoeia, diluted acetic acid is neutralized with ammonium carbonate; that is, carbonate of ammonium is added, a little at a time, to the diluted acetic acid until the reaction of the solution is neutral to test paper, or litmus paper. 1014. In testing liquids with litmus paper to ascertain their reaction, it is necessary that the coloring matter of the paper (the litmus) be soluble in or wetted by the liquid, for otherwise the color is not affected. Thus, to test strong ether, for instance, it is necessary to moisten the litmus paper with water before applying the ether to it. In testing solutions obtained by neu- tralizing acids with carbonates, it may be the case that the solution is charged with carbon dioxide (" carbonic acid") and will, therefore, give an acid reac- tion on test paper, even if the acid has been neutralized by the carbonate; if the liquid be heated sufficiently to expel the "carbonic acid gas," or car- bon dioxide, the reaction obtained will, however, be true and may be found to be neutral notwithstanding the fact that it was acid before the liquid was heated. 1015. Some salts are always alkaline in reaction, although they are normal salts, and even salts of an acid constitution — that is, salts still containing replaceable positive hydrogen — may have a decidedly alkaline reaction, as, for instance, potas- sium bicarbonate (acid carbonate of potassium), which at once turns red litmus paper blue. But this is because the carbonate radical is a very weak negative radical, while potassium is the strongest positive radical. Several normal salts of iron, zinc, etc., with the stronger acids, have an acid reaction, and even the basic ferric sulphate gives an acid reaction. This is because the sulphate radical is a CHEMISTRY. 305 very powerful negative radical, which the iron is not sufficiently strongly positive to neutralize it as to its effect on vegetable colors. It is, therefore, to be always borne in mind that a normal salt, which is often called a neutral salt, does not mean a salt with a neutral reaction on test paper, and that a salt having such a reaction is not necessarily a normal or neutral salt chemically. In other words neutrality to test paper and neutrality as to chemical structure or composition are two wholly different things. 1016. Soluble salts can not advantageously be prepared by double decomposition except when the bye-product is insoluble, so that the reaction is complete. But they can be made from acids by neutralization or saturation. Sulphate of zinc can be made by dissolving zinc in diluted sulphuric acid all that is necessary in this case is to add enough zinc — a little more than the- acid can dissolve — and to let the acid act upon the metal until it will not dis solve any more of it. The zinc will continue to dissolve just as long as there is any acid left ; but when all the acid has been saturated, or turned into zinc sulphate, no more zinc can be dissolved, for zinc is insoluble in a solution of its own sulphate. Similar results are obtained in many other cases when metals are dissolved in acids ; but not in all, for sometimes basic salts are formed if the metal is used in excess. If, instead of zinc, we should add the oxide of zinc, or zinc hydrate, or zinc carbonate, to the diluted sulphuric acid, the final result would be the same — zinc sulphate is obtained in either case. If the proportions of acid and metal, oxide, hydrate, or carbonate are exactly those required by theory, according to the chemical reaction, a nor- mal salt will generally be obtained; or, if the metal, oxide, hydrate or car- bonate is insoluble in a solution of the normal salt formed with the acid used, an excess of either of them may be added to the acid with the assurance that a normal salt is formed, and the bye-products in these reactions are either gases which pass off or water which is unobjectionable. When one of the prod- ucts of a reaction is either a gas or water the reaction also progresses to com- pletion. When carbonates are dissolved in acids the gas CO s together with water are the bye-products (1026). 1017. The proportions required by theory to an even neu- tralization or double decomposition are shown by the chemical equations which represent the reactions: Zn + H 2 SO, = ZnS0 4 + H 2 65 98 161 2 306 CHEMISTRY. Thus it requires 65 pounds of zinc and 98 pounds of sulphuric acid to make 161 pounds of zinc sulphate, and 2 pounds of hydrogen will be formed at the same time. As the hydrogen is a light gas insoluble in solution of sulphate of zinc, it easily passes off. But these proportions are theoretically right only in case the sulphuric acid is absolute (or a P/ ua/d Pf xaKov y "medicine," and yvwou?, "knowledge") is that branch of the study of medicines which treats of the natural origin, appearance, structure and other means of identification of organic drugs. The study of pharmacognosy necessarily demands a fair knowledge of the organs, tissues, and microscopical structure of plants, and also a sufficient general knowledge of systematic botany. Botanical drugs are sometimes so nearly alike that it is necessary to resort to the microscope to remove doubt. 1052. Identification of Medicinal Substances. — The ability to identify or recognize individual drugs, chemicals and ABOUT DRUGS. 32I pharmaceutical preparations is extremely valuable, since it is the means of detecting and preventing mistakes. Many of these substances may easily be recognized with the aid of the physical senses — sight, smell and taste. Familiarity with the more important drags, chemicals and pharmaceuticals that possess striking physical characteristics should, therefore, be cultivated. Crude drugs, especially, may often and with cer- tainty be recognized by the form, color, odor and taste. In other cases we may not be able to positively identify a drug by these physical properties, and yet when .a mistake has been made we may detect it by our ability to at least see that the article before us is not what it should be. But, although the external appear- ance and other physical properties of medicines should be famil- iar to us, and are the most valuable aids in detecting or avoiding errors, yet we must also make use of such other aids as we can render available for this purpose. A good knowledge of plant structure and plant organs, and ability to use the microscope, are necessary to proficiency in pharmacognosy. A knowledge of chemistry is requisite to identify chemical substances by appropriate qualitative tests ; and chemistry frequently aids us in identifying even Galenical preparations which are the most difficult of medicines to identify. Notwithstanding the difficulties, every good pharmacist should be able to identify such common preparations as the tinctures of opium, rhubarb, aloes or arnica; he should immedi- ately recognize the odors of jalap, ipecac, aloes or any other drugs which are equally characteristic in this respect. 1053. Varieties of Drugs. — Of many crude drugs there are several varieties. Thus we have several varieties cf ginger, cinnamon, sarsaparilla, catechu, cinchona, senna, etc. It is important that in each such case the particular variety or varie- ties intended should be plainly specified or described. When- ever any two varieties of the same drug differ greatly from each other they are in fact to be distinguished from each other as if they were different drugs, which, in effect, they really are. 322 ABOUT DRUGS. 1054. Grades. — Each drug should be in good condition. If it consists of a plant part it should be gathered at the proper season and the right stage of development, it should be properl; cleaned and garbled; and carefully dried and preserved so as t< be perfectly sound. But climate, soil and season, together with various othei influences affect the quality of drugs to so great an extent that there are nearly always different grades of each drug. The elevation at which the plant grows may increase or diminish its medicinal value. Wild growing plants frequently differ from the cultivated as to their virtues. If to these causes of varia- tion be now added the ignorance, or carelessness, or accidents by which the drugs are gathered too early or two late, in unsuitable weather, from plants that are too young or too old, or from unsound plants, or are badly cleaned and dried, and il preserved, it is not a matter of surprise that there are widely differing grades of drugs. When several grades of the same drug are simultaneous!] found in the market the competent, conscientious and prudent pharmacist will, of course, select the best. Sometimes the differences are so great as to be self-evident. Thus no one can fail to observe the difference between dry, sound, well-preserved, bright flowers, and mouldy, discolored ones; between lean ergot grains scarcely half an inch long and plump ergot over an inch in length; between green, healthy-looking leaves and brown or 3 r ellow, faded ones: between a sample having the proper strong characteristic odor of the drug, and one either having no odor at all or an odor not belonging to the sound drug; or between a drug full of inert stems, wood, sticks and stones, and another quite clean and free from all impurities or admixtures. But it happens most frequently that it requires special knowledge and training, such as only well educated and experi- enced pharmacists possess, to distinguish between good, bad and indifferent grades of the same drug. 1055. As the vegetable drugs are not only the most numer- 1 it ABOUT DRUGS. 323 ous, but also the most important of the materia medica, a good knowledge of pharmaceutical botany is necessary to every intel- ligent pharmacist. Morphology (from m<>pH "form," and A6yo?, " discourse") treats of the organs of plants and their forms, transformations, and relations. The study of the conspicuous organs of plants (as root, leaf, flower, seed) as to their external conformation is also called organography. Ability to distinguish between roots and stems, leaves and flowers, fruits and seeds, etc., is acquired by the study of organ- ography, and is a necessary preparation for the systematic study of pharmacognosy (105 1). A fair knowledge of the minute details of plant structure, or of the tissues of plants and the cells of which these tissues are composed, is also necessary to the intelligent study and identi- Acation of drugs. - This is called vegetable histology, and some- times micro-botany. Finally, the acquisition of a sufficient knowledge of botany and pharmacognosy absolutely requires the use of scientific ter- minology and nomenclature. Technical ter?ninology is, indeed, necessary to satisfactory progress in any scientific study. By technical terminology is meant a system of precise words or terms, suitable for constructing brief accurate descriptions and for exact expressions and descriptions of facts, conditions and ideas. A good technical term or word expresses a great deal, and expresses it accurately. Some valuable technical terms are so expressive that in their absence it would require a great num- ber of words to express their meaning without ambiguity. A right study of science serves to teach the student to use his five senses with fidelity, and to report with accuracy what they perceive. He learns to see all that is to be seen, not with his imagination, but with his eyes ; and he learns also to state just what he sees — no more, and no less. But quickness and truthfulness of observation and reasoning must be followed by accurate expression, and hence science has formed for itself a 324 ABOUT DRUGS. language by which knowledge maybe faithfully preserved, com- municated and increased. That language embraces technical terminology and nomenclature in its glossary. The term nomenclature is frequently used in the same sense as terminology, but nomenclature is a system of titles or names, only, whereas terminology embraces all other technical words as well as names. 1056. Officinal drugs, chemicals, and pharmaceutical prep- arations are those commonly found in the "officine." By " officine 5 ' is meant the apothecary's shoD. Any medicinal substance or preparation usually kept in drug stores is, therefore, " officinal." Any drug or preparation maybe officinal whether official (1059) or not. 1057. Magistral formulas and preparations are unofficial recipes and remedies prescribed by widely recognized high- medical authorities. 1058. Extemporaneous preparations are those not kept in stock or " ready made " but always prepared for the occasion whenever required. They are, of course, such preparations as would deteriorate if kept on hand. 1059. Official drugs, preparations and processes are those included in the national pharmacopoeias. But an official medi- cine is not necessarily an officinal one (1056). 1060. Pharmacopoeias (from , "medicine," and B-ocew, I "make") are books, compiled by governmental authority, or by authoritative national conventions, containing titles, definitions, descriptions, tests, formulas, and other informa- tion, directions and standards of quality, purity and strength for the medicines in common use. 1061. The Pharmacopoeia of the United States is pre- pared and published by authority of the National Pharmacopoeia! Convention. This Convention consists of delegates appointed by the several incorporated medical and pharmaceutical colleges and societies of the United States, the American Medical Asso- ciation, the American Pharmaceutical Association, and by the ABOUT DRUGS. 325 Surgeon Generals of the Army, the Navy and the Marine Hos- pital Service. The meetings of the Pharmacopceial conventions are held in Washington on or about the first day of May once in ten years. Pharmacopceial Conventions were thus held in 1820, 1830, 1840, 1850, i860, 1870, 1880 and 1890. 1062. The Authority of the Pharmacopoeia of the United States has been repeatedly sustained and enforced by Courts of Justice, by Congress in certain legislation, and by the Execu- tive Departments in official orders and regulations. 1063. The Objects of the Pharmacopoeia are to estab- lish the identity of medicines, and to prescribe standards by which we may insure uniformity in the quality, strength and methods of *preparation of the officially recognized drugs, chem- icals and pharmaceuticals. Uniformity in the materia medica and pharmacy is of the highest importance, for without it there can be no science in therapeutics. The Pharmacopoeia provides titles, definitions, descriptions, identity tests, purity tests, working formulas, standards of strength, etc., for medicines commonly employed. 1064. The Pharmacopoeia is the only national authority by which the quality, purity and strength of official medicines are governed. The several " dispensatories " and other compilations and commentaries are valuable according to their respective merits; but they are subordinate to the Pharmacopoeia in all matters touching the official standards. No physician and no pharmacist who has proper respect for his profession and its responsibilities can do without a copy of the Pharmacopoeia of the United States. Every physician should be acquainted with it; and every pharmacist should be familiar with all its details. 1065. Pharmacy is the art of selecting and preparing medicines. Its importance is manifest and great. Without medicines the physician is powerless ; without the co-operation 5-6 ABOUT DRUGS. of a competent pharmacist his course must be either the narrow- beaten path of mere routine, or doomed to disappointment and even dangers. An accomplished physician who has had time enough to become at the same time an accomplished pharmacist must be an extraordinary person, or must have very few patients and little else to attend to. An active physician finds it in every way disadvantageous to be his own dispenser. A good pharmacist must be able to identify medicines, must be a good judge of the quality of drugs and preparations, know how to test medicinal substances as to their purity and strength, to prepare them properly, and to combine and dispense them accurately, safely, and well. He must know enough about the drugs and their preparations to avoid incompatibilities., over- doses and all other dangers. The word si pharmacy'" is derived from the Greek word ^p^toxo;-, which means medicine. 1066. Pharmaco-Technology (from £a PM a*ov, "medicine," 7c- v -, "art," and Ao'70?, "discourse,'') is a treatise on the art of pharmacy, or the principles, processes, and manipulations applicable in preparing, examining and dispensing medicines. 1067. Dispensing Pharmacy is the art of combining and dispensing medicines. I: is the most important of all the responsible work which the pharmacist has to do. To be an ideal dispenser of physicians' prescriptions demands many qualifications. He must be familiar with the substances to be combined or dispensed and with their properties, their behavior toward each other, and their general effects upon man. He must be generally well informed, clear headed, wide awake, and careful. He must at all times be calm, courteous, and exhibit unfailing tact. He must be scrupulously neat, prompt, deft, accurate, and conscientious. 1068. Pharmacodynamics (from >:-,:... "medicine," ABOUT DRUGS. 327 and av'poptv, "power,") is that branch of pharmacology which treats of the quality, quantity and direction of the action or effects of medicines. 1069. Therapeutics (from t^pa™™, to "cure") is that branch of the study of Medicine which treats of the effects and modes of action of medicinal agents, and their applications for the relief or cure of pain or disease. 1070. Posology (from nwos, "how much," and Ad V o S "dis- course") is the consideration of the proper quantities or doses of medicines to be administered. A "posological table" is a tabular statement of doses. Doses are, of course, to a certain extent arbitrary. But they vary according to the age, sex, and condition of the patient and according to the effect it is intended to produce. A " medicinal dose " is a proper and safe dose; a " maximum single dose" is the largest dose of any particular medicine which it is considered proper and safe to administer; the " max- imum daily dose " is the largest total quantity of any medicine which it is proper or safe to administer in the course of a day or of twenty-four hours. A "toxic dose" is the quantity which when given at a single dose is liable to produce dangerous or injurious effects, or death. An "adult dose" is the full dose usually administered to a man of about 21 to 30 years. The "dose for children " is found by dividing the age (in years) of the child at its next birthday by 24 ; the fraction thus obtained is the proper fractional part of the adult dose that may properly be administered to the child. Thus, if the child's age at next birthday is 6 years, divide 6 by 24, which will give ft" or T At tne proper dose being, therefore, % of the dose for an adult (Dr. Cowling). 1071. Human Physiology is the study of the functions of the organs of the human body. Anatomy is the study of the structure, organs and parts of the body. Every intelligent pharmacist should know what a stomach 328 ABOUT DRUGS. is, or the liver, the heart, the blood vessels, muscles, bones, joints, etc. He should also have a fair knowledge of the ele- ments of human physiology, as of digestion, the blood, circula- tion, respiration, animal heat, the nervous system, etc. He should know something of hygiene, .food, ventilation, etc. He should certainly know what is meant b) r a tonic, cathar- tic, astringent, emetic, stimulant, sedative, diuretic and other common therapeutic terms. Finally, he should know what drugs are narcotic, the safe as well as toxic doses of poisonous substances ; what are the symptoms of poisoning by the common poisons, and the appro- priate antidotes that should be used in such cases in the absence of a physician. All of these things are taught in any good college of phar- macy. 1072. Toxicology is the study of poisons and their effects and proper antidotes. Poisons are substances producing fatal or dangerous effects upon the organs of the body or their functions. CHAPTER LXII. THE COLLECTION OF PLANT DRUGS. 1073. The medicinal value of plant drugs depends upon various conditions, as season, climate, soil, age, and develop- ment, whether the plant is wild-growing or cultivated, the part used, manner of collection, cleaning, pruning and garbling, cur- ing or drying, and preservation. 1074. Plant drugs are generally sensitive to exposure, and by far the greater number deteriorate so rapidly, even when carefully kept, that a fre*sh supply must be procured annually. The new annual supply of each drug should, of course, be pro- cured at the season when it is in its best condition. There is a ABOUT DRUGS. 329 proper annual season for gathering each plant drug, and it soon afterwards reaches the market through the drug brokers, and the new crop can then be obtained by the pharmacists, who ought to renew their stock of perishable drugs at that time. Some plant drugs can scarcely be preserved through one season without material deterioration; others are difficult to procure, of good quality, at any time, owing to the carelessness with which they are gathered, cured and shipped. Among the many perishable drugs are such important ones as ergot, dig- italis, erythroxylon, belladonna, pilocarpus, besides all herbs and flowers. 1075. The time for gathering any plant drug is that season at which it contains the greatest proportion of its active prin- ciples. The plant part which constitutes the drug should be well developed and perfectly sound; it should neither be so young, immature and poorly developed as to be deficient in active con- stituents on that account, nor should it be so overgrown or old as to have begun to degenerate. In most cases it is safe to assume that a drug which has the fresh natural color belonging to it well preserved, and which possesses in a high degree and unaltered the peculiar odor and taste which characterize it, will prove to be of satisfactory medicinal quality. It is always true that when the drug is dis- colored, or its odor or taste impaired, it can not be of good quality. 1076. In many plant drugs every part of the tissues is equally active ; in others again the softer, more friable portions are more active than the tougher tissues. Whenever the Pharmacopoeia defines a drug as consisting of any given plant organ or plant part, then no other portions of the plant must accompany the drug. Thus, when the bark of a root constitutes the drug, the whole root must not be used ; when the inner bark is the drug, it would not do to use both inner and outer bark together, nor to use the bark with pieces or shavings 3$0 ABOUT DRUGS. of wood attached; when the leaves constitute the drug, the stems do not belong to it, too ; and when the drug consists of the seeds, only, the whole fruit must not be used. Again, when the drug is defined to be leaves of the second year's growth, this definition clearly excludes the leaves of the first year's growth as unequivocally as it excludes the root, or the leaves of an entirely different plant. I077. To illustrate the care with which the Pharmacopoeia defines plant drugs, we may quote a few official definitions : Anthemis consists of " the flower-heads of Anthemis nobilis collected from cultivated plants/' Conium is defined as " the full grown fruit of Coniujn macu- latum, gathered while yet green." Calendula is defined as "the fresh flowering herb of Calen- dula officinalis.''' Digitalis is "the leaves of Digitalis purpurea, collected from plants of the second year's growth." Eucalyptus is "the leaves of Eucalyptus globulus, collected from rather old trees." Frangllla is "the bark of Rhamnus Frangula, collected at least one year before being used." Juglans consists of " the inner bark of the root of Juglans cinerea, collected in autumn." We also find in the Pharmacopoeia such directions as the following : Belladonna Root, — " Roots which are tough and woody, breaking with a splintery fracture, should be rejected." Colchicum Root " which is very dark colored internally, or breaks with a horny fracture, should be rejected." Cubeb " should not be mixed with the nearly inodorous rachis or stalks." Ergot "should be preserved in a dry place, and should not be kept longer than a year." Galla. — " Light, spongy and whitish-colored Nutgalls should be rejected." ABOUT DRUGS. 331 Prunus Virginia. — " The bark of the small branches is to be rejected." Senna. — "It should be freed from stalks, etc." 1078. Roots and rhizomes are generally gathered in the autumn, from plants of two or three years' growth, when the plant has withered or the leaves fallen; or they are sometimes gathered in the spring before tne leaf buds expand. They must be freed from earth; best by washing them with water. If thick and succulent, they are cut or sliced, either trans- versely or longitudinally, before being dried. Thick, juicy roots must be rapidly dried at a sufficiently high temperature to prevent discoloration, mould or fermentation. Spongy, decayed, discolored or otherwise unsound portions must be rejected. Some roots of biennials are to be rejected if woody; but the roots of trees and shrubs are always woody. 1079. Bulbs are sometimes preserved whole, as garlic and onions; but other bulbs are sliced and dried, as squill. Whole bulbs may be kept in nets or in dry sand. 1080. Barks and woods are taken in the spring before the leaf buds expand. The bark from branches of two to four years' growth is generally better than younger or older bark. Sometimes the whole bark is used, because a separation is impracticable; but whenever a separation can be effected, the inner bark alone is used. The old, dry, dead, outer corky layer is always worthless. Barks are easily dried when well spread out over enough sur- face in an airy, shaded place at ordinary summer heat. 1081. Herbs, leaves and flowers should be gathered in clear weather when the plants are dry and free from dew. Herbs must be fully grown, but gathered before flowering, or, if aromatic, immediately after the expansion of the flowers. Biennial herbs may generally be gathered at the end of the first summer, but sometimes (when narcotic) not until the second season. 332 ABOUT DRUGS. The herbs are dried in bundles hung up on strings, or spread out in thin layers on paper or muslin in an airy, shaded place. Leaves are treated much like the herbs. If of narcotic plants those of the second year's growth are used. Flowers are extremely sensitive, and require to be dried with great care to preserve their natural colors. They are gath- ered as soon as expanded, spread out well on paper, and dried in an airy, shaded place at ordinary summer heat, being stirred or turned frequently until quite dry. 1082. Fruits are gathered when fully ripe, except when succulent. Hard, dry fruits are easily sufficiently cured to insure their preservation. 1083. Seeds must be fully developed when gathered, and are easily dried. Sometimes they are best preserved in their capsules. 1084. When sufficiently dried the plant drugs should be put into suitable receptacles, such as tin cans, or tightly closed bot- tles, or well made drawers with snugly fitting covers. They must be protected against light, exposure to the air or to moisture, and against too high temperature. In other words, plant drugs must be kept in well closed receptacles in a moder- ately warm, shaded place. CHAPTER LXIII. THE CHEMICAL CONSTITUENTS OF PLANT DRUGS. 1085. The proximate principles of plant drugs are the several kinds of chemical constituents naturally formed and contained in plants and separable from the plant parts as well as from each other by the aid of different solvents. ABOUT DRUGS. 333 1086. The Classification of Plant Constituents.— The proximate principles of plant drugs may be grouped into a limited number of classes, as follows : 1. Cellulin (or cellulose) and its modifications, as lignin etc. (1090). 2. Starches, or amylaceous substances (1092). 3. Gums, or vegetable mucilages (1093). 4. Pectinous substances (1099). 5. Sugars, or saccharine substances (1100). 6. Albuminous substances, or vegetable albumin (1104). 7. Fixed oils, or fats (1105). 8. Organic acids (mi). 9. Volatile oils (1112). 10. Resins (1118). 11. Neutral principles not belonging to any of these other classes (1125). 12. Alkaloids (1128). 1087. Of these twelve classes of proximate principles only cellulin (or cellulose) in its various forms is entirely insoluble in all the ordinary simple solvents, such as water, alcohol, ether,, benzin and chloroform. All the other classes of proximate principles are soluble in one or more of the solvents named, and can, therefore, be extracted from the drugs in which they are contained. 1088. The Inert Constituents of Plants.— The sub- stances belonging to either of the first eight classes enumerated (1086) exhibit no decided medicinal action ; they are either absolutely inactive or have but a very mild effect. 1089. The Active Principles of plants are either volatile oils, resins, neutral principles belonging to class n (1086), or alkaloids. Many plant drugs contain but one " active principle "; others two, or three, or more. In a drug containing several active constituents, all of them may belong to the same class of proxi- mate principles, or each may belong to a di# erent class. 334 ABOUT DRUGS. 1090. Cellulin and lignin. — The substance of which cell walls, cell membranes, and fibres are constructed is called cellu- lin or cellulose, and it occurs in various modifications and forms. Lignin is the altered cellulin which constitutes wood and woody Jibre. Plant drugs containing large quantities of woody fibre are called fibrous, and their powders are fibrous powders. Woody roots are tough because of the large proportion of lignin they contain. 1091. As the other proximate constituents of plants are contained in the little closed sacs' or cells, which are made up of cellulose, or in the little spaces between those cells, or in canals, cavities or vessels bounded by cell walls or cellular tissues, it follows that whenever the extractable substances are to be removed from any drug consisting of plant organs, or when, its soluble matters are to be extracted, the solvent used must either be capable of passing through the vegetable membranes into the closed cells and other cavities, dissolving the substances contained within them, and then passing out again carrying with it the dissolved matters, or, if the solvent can not thus pass through the membranes, the drug must be disintegrated so that the solvent can come in direct contact with the proximate principles when the cells and intercellular spaces shall have been broken open. 1092. Starches or amylaceous substances are contained in numerous plant drugs. You are acquainted with corn starch, laundry starch, arrow root, and perhaps other kinds of starch. Similar starches are found in drugs. Starch consists of little granules so small that they can be well seen only w T ith the aid of a good microscope. The size, form and markings of the starch granules differ according to the plant in which the starch is contained. Hence many drugs may be identified by their peculiar starch granules. Starch in its normal condition is insoluble in water, alcohol, ether and other simple solvents. But when starch is heated it is altered in properties and becomes soluble. With hot water ABOUT DRUGS. 335 it forms a translucent mucilaginous solution or paste, according to the proportions of the two ingredients. When boiled with water to w r hich a little sulphuric acid has been added, the starch is converted into glucose (hot"). When dry starch is subjected to high heat it is converted into a gummy, water-soluble substance called dextrin. 1093. Gums. — Two gums are contained in the Pharmaco- poeia. They are acacia and tragacanth. But there are several so-called inucilaginous drugs in the official materia medica. "Mucilaginous drugs" are drugs containing considerable quan- tities of gum and from which mucilages or mucilaginous infu- sions can be made. Thus the Pharmacopoeia contains mucilages made of quince seed, sassafras pith and slippery elm bark, as well as mucilages of acacia and tragacanth. There are also other drugs containing large quantities of gum or vegetable mucilage, as, for instance, althaea, flaxseed, senna, buchu, etc. 1094. Gum, or vegetable mucilage, is a substance which either dissolves or swells in water, forming, if the quantity of gum is sufficient, a thickish, viscous, sticky solution, or a jelly- like paste, called a mucilage. The various kinds of gums, dif- fering according to their source, are grouped into two classes: 1, those which, like acacia, are entirely soluble in water, form- ing perfect or homogeneous solutions; 2, those which, like trag- acanth, simply absorb a large quantity of water, swelling in it so as to form translucent gelatinous masses or pastes, but do not form perfect or homogeneous solutions. 1095. Nearly all plants and plant drugs contain more or less gum or vegetable mucilage, which is formed by the meta- morphosis of plant tissues, as, for instance, of seed coats, on the inner surface of inner barks, etc.; or, in large accumulations, by the breaking down of plant tissue. 1096. Gum is hard when dry; does not soften, but, on the contrary, hardens when heated, and if the temperature is raised higher the gum becomes decomposed charred or carbonized, but does not ignite and burn with a flame. Gums in solution readily ferment or become sour. 336 ABOUT DRUGS. Gum is insoluble in alcohol, ether, chloroform, volatile oils and fixed oils. 1097. The term " gum " is very generally misapplied. Thus we hear camphor, aloes, opium, guaiac, copal, kino, catechu, asafcetida, and many other substances called gums. But noth- ing that is soluble in alcohol or diluted alcohol can be a gum. 1098. Gums and mucilaginous drugs are used for preparing demulcent drinks and injections, to hold insoluble substances in suspension in mixtures, as binding excipients in pill masses and troches, etc. 1099. Pectinous substances are contained in very many fruits, and often also in other plant parts. The most striking property of pectin is that it forms jelly. Jellies can be made of fruits because they contain so much pectin. Pectin is, like gum, water-soluble, but not soluble in alcohol, and it readily under- goes fermentation. 1100. Sugars of various kinds exist in plants, and also in animal substances, as in milk and honey. They are more or less sweet to the taste, cane sugar being the sweetest, and milk sugar the least sweet. Sugars are always water-soluble, but milk sugar is not freely soluble in water, while other sugars dissolve in such large pro- portion as to form very thick syrups. Sugar is also alcohol soluble to a limited extent. A satu- rated water solution of sugar can be mixed with alcohol without separation of the sugar from its solution. 1101. Ordinary white sugar is "cane sugar," saccharose, or sucrose. Beet-root sugar, sorghum sugar and maple sugar are precisely the same kind of sugar as that obtained from the sugar cane; but maple sugar is mixed with other substances derived from the maple sap which give it its peculiar agreeable flavor; when purified it can not be distinguished from cane sugar, nor can pure sorghum sugar and pure beet root sugar be recognized as in any manner differing from the refined sugar of the sugar cane. ABOUT DRUGS. 337 Rock candy is crystallized cane sugar or saccharose. Milk sugar is also crystallizable. Grape sugar is the non-crystallizable sugar contained in grapes and many other fruits. It is also frequently called glucose. But the term " glucose " is now generally applied to the sugar manufactured from starch (1092). The saccharine substances used in pharmacy include: cane sugar, milk sugar, honey and manna. 1102. Sugars belonging to the class known as "glucoses" have the composition C 6 H 12 6 , and readily undergo fermenta- tion. Sugars belonging to the class called "saccharoses" have the composition C^H^On, and do not ferment unless first changed into glucose sugar. The products of the fermentation of sugar are alcohol and carbon dioxide. But fermentable sugar does not undergo fermentation when in the form of very dense syrup, while even cane sugar rapidly passes through the glucose stage and ferments if in the form of a weak water-solution. In fact a syrup of sugar, or simple syrup made of pure white sugar, will keep in warm weather only if so strong as to contain nearly two-thirds sugar. The official " syrup " is a solution of 65 pounds of sugar in 35 pounds of water, and is not too concentrated, for it would ferment in the summer season if weaker. Contact with air is a necessary condition to the fermentation of sugars. A weak solution of sugar ferments because it dis- solves air; but a dense syrup can not contain air and, therefore, does not ferment. 1103. Sugar is used in pharmacy and medicine for three pur- poses: 1, as a diluent; 2, to sweeten medicinal preparations; 3^ to preserve organic medicinal substances from fermentation and other chemical changes. Both ordinary sugar (cane sugar and beet sugar) and milk sugar are used as diluents of powders. Sugar is much used to sweeten medicinal preparations, as in lozenges, confections, syrups, mixtures, etc. 3$& ABOUT DRUGS. It preserves moist drugs and preparations by taking up the moisture forming a thick syrup or a coating of sugar by which the moist organic matter is enveloped and air excluded. 1104. Albuminous matters are nitrogenous substances soluble in water when in their normal condition but coagulating when heated. A typical example of albumin is furnished by the white of egg; as taken from a fresh egg it is transparent, liquid, and water-soluble; but when boiled it becomes white, opaque, solid, insoluble, and this change is called coagulation. There are similar substances contained in plant drugs and called vegetable albumi?z, or albuminoids. The white fleshy portion of the almond is a vegetable albumin which has received the name emulsin, and sometimes the name synaptase. Albuminous substances do not ferment, but they undergo putrefaction. Their presence in certain pharmaceutical prepara- tions is, therefore, to be avoided, and they may be coagulated and removed by heat, or by the use of alcohol in which albumin is insoluble. 1 105. Fixed oils or fats. — There are many different kinds of fixed oils or fats employed in pharmacy and medicine, espe- cially in the preparation of ointments, cerates, liniments, sup- positories, etc. Fats are also used in the manufacture of soaps. Among the most familiar examples of fixed oils or fats are: lard, butter, suet, tallow, wax, spermaceti, lanoleum, cacao but- ter, lard oil, cotton seed oil, mustard seed oil, olive oil, castor oil, cod liver oil, flaxseed oil, etc. 1106. Fixed oils are all absolutely insoluble in water; with rare exceptions (castor oil and croton oil) they are but slightly soluble in alcohol, readily soluble in ether, disulphide of carbon, benzol and benzin; and they form true soaps with the alkalies. Nearly all the common fixed oils or fats consist chiefly of the oleate, stearate and palmitate of glyceryl. Glyceryl is a tri- valent hydrocarbon radical C 3 H 5 . Its hydrate is familiar to us under the name oi glycerin, C 3 H 5 (OH) 3 . The oleate of glyceryl is often called olein, and olive oil is nearly all oleate of glyceryl, or olein. Chemically considered the oleate of glyceryl is a ABOUT DRUGS. 339 salt. It is a very fluid fat, and all liquid fats or fixed oils con- tain it, their fluidity being proportional to the percentage of olein, while the solid fats contain greater proportions of the stearateof glyceryl (stearin) and palmitate of glyceryl (palmitin). Oleic acid, stearic acid and palmitic acid, are always made from fats; their glyceryl salts are the true fats; their salts with potassium and sodium are soft or hard soaps; and their salts with the heavy metals are the true plasters. When perfectly pure the fats are usually colorless or white, odorless, tasteless, perfectly bland, without any medicinal effect. They always have a greasy or unctuous feel, are lighter than water so that they always float upon it, and they are non-volatile or fixed so that they can not be distilled, and when dropped upon clean white paper, leave a permanent stain. 1 107. The liquid fixed oils or fats are classified into drying oils, and non-drying oils. The drying oils harden or dry upon exposure to the air in thin layers, as is the case with flaxseed oil; the non-drying oils like oil of almond never dry or harden. 1108. Castor oil is a remarkable fixed oil because unlike all other fixed oils it is entirely soluble in or miscible with strong alcohol in all proportions forming perfectly clear mixtures. Croton oil, when old, is also soluble in alcohol to a considerable extent but forms turbid solutions or mixtures with it. 1109. Under the combined influence of moisture, air, and warmth most of the oils become rancid, especially the animal fats. When oleic acid, lard, and other fatty substances become rancid they contain oxyoleic acid, have an offensive odor, and are irrita?it instead of bland. They are then unfit for any medicinal uses. 1110. Fixed oil is always contained in seeds. Hence drugs consisting of seeds sometimes require special treatment in mak- ing solid extracts and other pharmaceutical preparations of them, for if their active constituents are such as require a strongly alcoholic menstruum for their extraction a considerable quantity of fixed oil or grease will also be simultaneously dissolved by the menstruum, and the product rendered greasy. Weak alco- hol does not extract the fixed oil. But the fat may often be 34° ABOUT DRUGS. removed from the seed with ether, before extracting the medi- cinal constituents; or if the fixed oil is extracted by the alcohol together with the active constituents, it can be separated from the product afterwards. 1111. Organic acids are contained in all plants. In some fruits there are large quantities of fruit acid, as tartaric, citric, malic, succinic and oxalic acids. But these acids do not possess any decided medicinal action, except that their salts are laxative or cathartic, or are used as cooling drinks or fever-mixtures, or as mild diuretics. Other organic acids occurring in comparatively small quan- tities are numerous in the plant world, but there is no import- ant plant drug possessing decided physiological effect that has been shown to owe its medicinal action to any organic acid. 1112. Volatile Oils are a numerous and mixed class of sub- stances widely distributed among the plants. They seem to occur in nearly all plants, although generally in extremely small amounts, and although they are more common and abundant in certain fruits and flowers, they occur also in leaves and all other plant parts. The volatile oils contained in the Pharmacopoeia are many and include such typical representatives of the whole class as the oils of: turpentine, lemon, orange, anise, peppermint, cinna- mon, sassafras, cloves, wintergreen and camphor. There are also many drugs containing volatile oils as their most important constituents, as, for instance: cloves, carda r mom, buchu, eucalyptus, etc. 1113. Volatile oils are generally liquid at ordinary tempera- tures, have an aromatic odor, are very slightly soluble in water but generally readily soluble in alcohol and ether, they have a pungent taste, and are volatile so that they can be easily dis- tilled and do not leave a permanent stain when dropped on paper. Volatile oils are also called "essential oils," and "ethereal oils," and the terms u otto" and " attar " have recently been proposed to distinguish volatile oils from fixed oils. There ABOUT DRUGS. 341 is no similarity between fixed oils and volatile oils except that both have an "oily appearance " and are immiscible with water. Volatile oils are not salts; they contain neither glyceryl nor fat acids. But a large number of the volatile oils are saturated hydrocarbons of the series called terpenes, having the formula (C 10 H 16 ) n ; other volatile oils are oxidized hydrocarbons, and some volatile oils contain sulphur, cyanogen, and other radicals. Most of the volatile oils are lighter than water; but some of them, as the oils of cloves and wintergreen, are heavier. 1114. Many of the volatile oils consist of a liquid portion called the elceopten, and another portion called the stearopten, which is solid when separated from the elseopten. The stear- optens of volatile oils are often called camphors, and ordinary camphor is a stearopten. As a rule a volatile oil is not a single definite substance, but a mixture of several different kinds of substances. 1115. Most of the volatile oils of the terpene series, if not all of them, deteriorate rapidly unless kept in small, filled, tightly stoppered bottles in a dark, cool place. If exposed to air, light and warmth they resinify — that is, they take up oxygen, and as they are oxidized resinous products are formed by which the volatile oils are changed in composition, color, density and odor. 1116. Volatile oils are obtained from the plants and plant parts either by distillation (with the aid of water), or by expres- sion, or by extraction with alcohol or with fixed oils. 1 1 17. Nearly all flowers, fruits, herbs, leaves, and other plant parts possessing an aromatic odor contain one or more volatile oils, to which their odor is due. All volatile oils, and plant drugs containing them, are aromatic stimulants, and some of them are anthelmintics, while nearly all act upon the kidneys. 1118. Resins are solids or semi-solids, they soften and then liquefy when heated; they are non-volatile, readily combus- tible, being easily ignited, burning with a sooty, smoky flame; insoluble in water, alwavs alcohol-soluble, and often also soluble 342 ABOUT DRUGS. in ether, benzin, volatile oils, fixed oils, and chloroform. They are generally weak acids, and formed by the oxidation of volatile oils. They do not contain nitrogen. Resins may be classified into dry, hard resins, which are gen- erally amorphous and of a glassy fracture, though sometimes crystalline, and as a rule not acrid or irritating when applied to the skin; and soft resins, which are usually acrid, non-drying. Some of the acrid resins are hard, however. There are sev- eral resins so acrid as to vesicate the skin. Other resins are cathartics. 1119. Resins are used in the preparation of some plasters,, cerates and even ointments. Solutions of resins in oil of tur- pentine, benzin, or alcohol are varnishes. Resins, being weak acids, form soap-like compounds called resin-soaps with the alkalies. 1120. Among the common resins are ordinary "rosin," copal, dammar, mastic, sandarac, guaiac resin, scammony, amber, benzoin, shellac, so-called " spruce-gum," burgundy pitch, etc. 1121. As the resins are formed by the oxidation of volatile oils, and as the volatile oils are mixtures, the resins thus pro- duced are also mixtures. Moreover, resins and volatile oils are commonly associated together. Oleoresitis are mixtures of vola- tile oil and resin; thick turpentine, Canada turpentine, copaiba, etc., are oleoresins. Balsamic resins are such resins as contain either benzoic or cinnamic acid, or both, as benzoin and tolu; and balsams are fluid balsamic resins, as " balsam of Peru and storax." 1122. Spices are drugs containing agreeable pungent oleo- resins, or pungent resins, or pungent volatile oils. They are mostly oleoresinous drugs. But there are also several oleo- resinous drugs which are used solely for medicinal purposes and are not spices or condiments. Capsicum, pepper, cubeb, asarum, aspidium, cypripedium, iris versicolor, ginger, lupulin, are oleoresinous drugs. 1123. Gum-resins are mixtures of gum and resin, and they usually also contain small quantities of volatile oil, which is fre- ABOUT DRUGS. 343 quently the only constituent of any medicinal value. The gum. resins of the Pharmacopoeia are ammoniac, asafcetida, gal- banum, gamboge and myrrh. 1 124. Coloring matters are very generally of a resinous nature. Thus the green coloring matter of leaves, called chlorophyll, is resinous, alcohol soluble, insoluble in water. Other coloring matters — red, yellow, and brown — are more frequently alcohol soluble than water soluble. Hence alcoholic tinctures and extracts are as a rule more highly colored than aqueous prepa- rations. 1125. Neutral principles, not belonging to any of the dif- ferent classes of proximate principles enumerated in this chap- ter, are of a very miscellaneous chemical character. They are often of the class known as glucosides (977), sometimes weak acids, sometimes other compounds. As to their physical properties many neutral principles are crystallizable while others are amorphous ; many are water- soluble and a still greater number soluble in diluted alcohol or in undiluted alcohol, but others may be insoluble in one of these liquids. A large number of the neutral principles are purely bitter stomachic tonics ; others are acrid, or even narcotic ; and others, again, seem to be wholly inert, as, for instance, asparagin. The Glucosides possess medicinal activity more frequently and more decidedly than other neutral principles contained in plant drugs. Among the most common neutral principles of plant drugs are salicin, populin, phlorizin, amygdalin, saponin, coumarin, aloin, cathartin, and elaterin; and among the important drugs whose active principles belong, to this class are rhubarb, senna, senega, squill, digitalis, brayera, aloes, and colocyrith. 1126. Many of the acrid drugs, such as squill, digitalis, senega, etc., are drugs containing glucosides. But there are also acrid drugs which owe their acridity to acrid soft resin or some acrid volatile oil, or to some acrid alkaloid. 344 ABOUT DRUGS. 1127. Astringent Drugs contain tannin. Tannin, or tannic acid, is a peculiar neutral principle or a weak acid, having a powerfully astringent effect. Tannin darkens iron salts, and forms insoluble compounds with all metallic salts. Ink is made by mixing decoction or infusion of nutgall or madder (contain- ing tannin) with solutions of sulphates of iron. Tannin also has the property of tanning hides, forming a tough substance called leather when it acts upon the tissues of the fresh rawhide. Insoluble compounds are formed by tannin also with a number of other organic substances, as gelatin, alkaloids, etc. Among the most important of our astringent drugs are tannin itself, nutgall, oak bark, logwood, catechu, kino, krameria, geranium, rubus, rhus glabra, and uva ursi. 1128. Alkaloids are the most powerful of all the active principles of plant drugs. Alkaloids are organic bases having an alkaline reaction on test paper and capable of combining with and neutralizing the acids to form salts. They are called alkaloids because they resemble the alkalies in the before-mentioned properties. 1129. Many alkaloids are formed and contained in growing plants; others are not found in the living plants but formed by certain reactions in the contents of plant juices after death, as when morphine and the other opium alkaloids are formed during the process of drying the juice of the poppy capsule. Among the most important of our alkaloids are quinine, mor- phine, strychnine, atropine, cocaine, physostigmine, and aconi- tine. Among the most important drugs whose medicinal value depends upon alkaloids we have aconite, belladonna, coffee, cinchona, colchicum, conium, erythroxylon, gelsemium, hydrastis, hyoscyamus, ipecacuanha, lobelia, nux vomica, opium, physo- stigma, pilocarpus, sanguinaria, stramonium, tobacco, and vera- trum viride. Over two-thirds of all known plant drugs containing alka- loids are poisonous. 1130. Alkaloids in the free state are generally alcohol- soluble, rarely water-soluble; but their salts with the stronger ABOUT DRUGS. 345 acids are generally water-soluble, not generally alcohol- soluble. Alkaloids and their salts are bitter or acrid to the taste. They may be classified according to their chemical composi- tion into two groups ; 1, the amines', and 2, the amides. The amines consist of carbon, hydrogen and nitrogen, and are called ternary alkaloids for that reason. They are liquid, vola- tile, odorous. Nicotine (the alkaloid of tobacco), coniine (the alkaloid of conium), and lobeline (the alkaloid of lobelia), are amines. The amides contain oxygen as well as carbon, hydrogen, and nitrogen. They are accordingly called oxygenated or quaternary alkaloids. They are solids, not volatile, odorless. By far the greater number of alkaloids belong to this class. CHAPTER LXIV. ROOTS, RHIZOMES, CORMS AND BULBS. 1131. Aconitum. Aconite. From Aconitum Napellus {Ranunculacecz). Mountain districts of Europe and America. Tuberous, tapering, about 2 in. long, x / z to ^ in. thick at the top; very •dark grayish-brown exteriorly, whitish interiorly; odorless; taste first insipid, afterwards acrid; produces tingling and numbness in the throat. Active principle — The alkaloid aconitine. A cardiac sedative. Dose of the drug 1 to 2 grs.; Abstract, ^to 1 gr. ; Extract, }£ to l / z gr. ; Fluid Extract, ^ to 2 min.; Tincture, 1 to 5 min. Poisonous effects. — The action of an overdose is rapid. Weakness, stupor, and paralysis are the successive symptoms. Death results from paralysis of the muscles of respiration and of the heart. Antidotes. — The patient should lie down, the stomach be emptied, and alcohol, ether, or spirit of ammonia administered. 1132. Allium. Garlic. The fresh bulb of Alliwn sativum (Liliacece). 346 ABOUT DRUGS. The garlic consists of about 8 wedge-shaped bulblets. Strong, offensive odor and a disagreeable, acrid taste. Contains acrid volatile oil. . 1133. Althaea. Marshmallow. From Althaa officinalis (Malvacece). Continental Europe. Cylindrical, or nearly so, 3 to 6 in. long, ]/ z in. in diameter, deep- wrinkled; decorticated, white, fibrous, starchy; odor faint; taste sweetish, mucilaginous. Demulcent. 1 134. Aspidium. Male Fern. The rhizome of Aspidium Filix-mas and A. marginale (Filices). All temperate countries. Pieces about 3 to 6 in. long, about % to 3^ in. thick; either peeled or covered with the remnants of the stipes; should be pale green, all brown portions to be removed ; odor disagreeable though faint ; taste slightly astringent, bitterish, acrid, disagreeable. Contains volatile oil, resin, fixed oil and filicic acid. It is a tcenicide. The Oleo-resin is the only official preparation; dose, 10 to 30 min. 1135. Belladonnas Radix. Belladonna Root. F r o m A tropa Bella donna ( Sola nacece) . Central and Southern Europe. Long, generally tapering pieces, y 2 in. or more thick, wrinkled length- wise; grayish exteriorly, whitish interiorly; odor faintly narcotic; taste bit- terish, finally acrid; should break with a nearly smooth fracture; tough, woody, splintery roots are to be rejected. Active principles. — The alkaloids atropine, belladonnine and hyscyamine.. Mydriatic, anodyne, antispasmodic, cardiac and vaso-motor stimulant. Dose. — Fluid extract, 1 to 3 min. Poisonous effects. — Headache, vertigo, greatly disturbed vision, delir- ium, motor paralysis, stupor, convulsions Antidotes. — Evacuation of the stomach, followed by the administration of opium, morphine or physostigma. 1 136. Calamus. Sweet Flag. The unpeeled rhizome of Acorus Calamus (Aracece). The United States. Europe. Long pieces, about % in. thick, wrinkled lengthwise; exteriorly brown- ish, interiorly whitish- spongy, fracture short; odor aromatic; taste sweetish,, bitterish, pungent. ABOUT DRUGS. 347 Contains volatile oil, resin and the bitter principle acorin. Aromatic stimulant and tonic. Dose of the Fluid Extract, 15 to 60 minims. 1 137. Calumba. Columbo. The root of Jateorrhiza Calumba (Menispermacece). Eastern Africa. Circular slices, 1 to 2 in. diameter, about \ \.o\ in. thick; cut surfaces con- cave; outer edge brownish-gray, broad surface yellowish-gray and often bright yellow near the epidermis; fracture short; odor faint; taste bitter, mucilaginous. Constituents. — The bitter principles calumbin, calumbic acid and berberine,. Also starch and mucilage. A bitter stomachic tonic. Doses. — Fl. Extr. 15 to 75 min.; Tinct. , 1 to i\ fi. dr. 1138. Cimicifuga. Black Snakeroot. Rhizome and rootlets of Cimicifuga racemosa (Ranunculacece) . The United States. Rhizome short, thick, branched, covered with many long rootlets, brownish-black, nearly odorless, bitter, acrid. Contains a very acrid neutral principle and resin. Dose. Fl. Extr., 10 to 30 minims; Tinct., 30 to 75 minims. 1139. Colchici Radix. Colchicum Root. The corm of Colchicum autumiiale (Melanthacece). Middle and Southern Europe. Ovoid, flattish, with a groove on one side. Generally sliced. Exteriorly brownish, somewhat wrinkled; interiorly white, starchy, odorless, sweetish, bitter, acrid. Active principle. — The acrid alkaloid colchicine. Alterative and diuretic. Dose. — Extract, % to i\ grains; Fluid Extract, 2 to 5 minims; Wine, 10 to 30 minims. Poisonous effects. — Pain in the stomach and bowels; watery stools; collapse. Antidotes. — Emetics, purgatives, and afterwards opium and alcoholic stimulants. 1 140. Gelsemium. Yellow Jasmine. Rhizome and rootlets of Gelse??iiu??i scmpervirens {Loganiacea), Southern United States. Branched rhizomes about \ to 1 inch or more thick; rootlets longer and much thinner; brownish-yellow; tough, woody fracture; heavy odor, bitter taste. 348 ABOUT DRUGS. Active principle. — The poisonous alkaloid Gelsemine. A motor and sensor depressant and cardiac sedative. Poisonous effects. — Depres-sion, respiration and heart action becoming labored; cerebral disturbance; general paralysis. Antidotes.— After evacuation of the stomach, alcoholic stimulants, spirit of ammonia; artificial warmth and respiration; digitalis and belladonna. 1141. Gentiana. Gentian. From Gentiana lutea (Gentianacece) . Central and Southern Europe. Pieces about 2 to 3 inches long, % inch thick; thicker pieces usually split; •deeply wrinkled lengthwise, more or less distinctly marked by transverse rings; exteriorly dark yellowish-brown, interiorly lighter. Brittle when dry, flexible when damp; odor characteristic, somewhat aromatic; intensified by moisture; taste bitter. Contains the bitter principle gentio-picrin. Also genti sic acid which darkens iron salts. Gentian is a bitter stomachic tonic. 1 142. Glycyrrhiza. Licorice Root. From Glycyrrhiza glabra (Leguminosce). Southern Europe. Long, cylindrical pieces, from 34 to 1 inch in diameter, wrinkled length- wise, exteriorly (the bark) grayish-brown, interiorly yellow; fracture woody, coarsely fibrous; inodorous; taste sweet, leaving a somewhat acrid after- taste. Contains the sweet substance called glycyrrhizin; also starch, gum, and some acrid resin. Preparations. — Extract, Fluid Extract, Ammoniated Glycyrrhizin. Com- pound Powder. 1143. Hydrastis. Golden Seal. The rhizome and rootlets of Hydrastis canadensis {Ranuncu- lacece) . The United States. About 1% inches long, rhizomes, 34 inch thick, wrinkled, yellowish-gray; fracture short, orange-yellow; rootlets thin, brittle; odor faint; taste bitter. Active Principles. — A white alkaloid, hydrastine, and the yellow, alka- loid berberine, both bitter. Tonic, diuretic, etc. Preparations. — Fluid Extract and Tincture. ABOUT DRUGS. 349 1144. Ipecacuanha. Ipecac. From Cephae'lis Ipecacuanha {Rubiacea:). Brazil. Crooked pieces, about 3 to 5 inches long, yk inch thick; dull grayish-brown, finely wrinkled, marked by numerous rings, close together, bark thick, often broken transversely; easily separated from the thin, tough, ligneous cord; odor not strong, but quite characteristic, nauseous; taste bitterish, acrid, sickening. Active principle. — The alkaloid emetine. The drug is emetic; in small doses expectorant and diaphoretic. Doses — Emetic: Powder, 15 to 30 grs.; Fluid Extract, 15 to 30 minims; Syrup, 4 to 6 fluidrachms; Wine, 3 to 5 fluidrachms. Expectorant: Fluid extract, 1 to 4 minims; Syrup, 1 to 2 fluidrachms; Wine, 10 to 30 minims. 1145. Iris Versicolor. Blue Flag. The rhizome of Iris versicolor (Iridacecs). Middle and Southern United States. Long, jointed pieces, cylindrical or flattish. marked by scars, wrinkled, annulated, grayish-brown; taste acrid, nauseous. Contains volatile oil and acrid resin. Purgative and diuretic. Dose. — Extract, % to 1 gr. ; Fluid Extract, 30 to 60 minims. 1 146. Jalapa. Jalap. The tuber of Exogonium purga (Convolvulacea). Mexico. Turnip-shaped, or oblong, varying in size, larger roots split, wrinkled, with short transverse ridges, dark brown, hard, heavy, interiorly pale grayish- brown; fracture smooth, resinous; odor slight sweetish, but quite peculiar, smoky; taste sweetish, acrid. Each 100 grains of Jalap must yield at least 12 grains of resin; and not more than 1.2 grains of that resin should be soluble in ether. Contains the cathartic resin called Convolvulin. Purgative Dose. — Powder 10 to 20 grs.; Abstract. 5 to 10 grs.; Alcoholic Extract 2 to 8 grs.: Fluid Extract, 10 to 20 minims; Compound Powder, 10 to 30 grs.; Resin, 2 to 6 grs. 1 147. Krameria. Rhatany. From Krameria triandra and K. tomentosa (Polygalacece). Northern parts of South America. Knotty, irregularly shaped, branched roots, sometimes about one inch or mere thick: rust-brown; but the better Krameria consists of long, cylin- ^ZO ABOUT DRUGS. drical roots not over }$ to j£ inch thick, dark purplish-brown : bark thick, and should constitute about one-third of the drug; wood tough, light brownish. Contains k> anuria-tannic acid (about 20 per cent.). Astringent. Dose. — Extract, ^to 15 grs.: Fluid Extract, 30 to 60 minims; Syrup, % to 4 fluidrachms; Tincture % to 3 fluid drachms. 1148. Leptandra. Culver's Root. From Leptandra virgitdca \Scrophulariacca?). The United States. Rhizome from 4 to 6 inches long, and about % inch thick, somewhat irregular in shape, blackish-brown, with cup-shaped scars above ; hard, with a woody fracture, wood yellow; rootlets thin, wrinkled, brittle; inodorous, bitter, acrid. Contains the acrid principle called :z ?;>::>: t:c;e:her with acrid rer.r Dose. — Extract 1 to 2 grs.; Fluid Extract 30 to 60 minims. 1 149. Pareira. Pareira Brava. From Chondodendron tomentosum (3femsper?nacece). Brazil and Peru. Round, crooked pieces, about 4 to 10 inches long, from % to 3 inches thick ; exteriorly brownish-gray ; furrowed lengthwise, with transverse ridges and fissures ; interiorly paler brown, marked by two or more irregular, con- centric circles of distinct rays. Contains the bitter alkaloid buxinc, also called " cissampeline. " or ""pelosine ." Tonic and diuretic. Dose of Fluid Extract, 30 to 60 minims. 1150. Phytolacca^ Radix. Poke Root. From Phytolacca decandfj (Phytclaccacccc). The United States. Large, usually sliced, fleshy, wrinkled, light grayish ; hard : fracture fibrous, the wood bundles in concentric circles; taste sweetish, acrid. Active principle possibly an alkaloid, (domains acrid resin. It is nar- cotic. Dose c: Fluid Extract. 1: to y: minims. 1151. Podophyllum. Mandrake. Rhizome and rootlets oi P c dophyllum peltatum (Berberidacca). The United States. Long jointed cieces. each joint about i 1 , to 2 inches long, about % inch or mere thick : a circular stir : ~. the upper side at each joint, rootlets on the ABOUT DRUGS. 351 ■under surface, or small white scars left after them ; smooth or slightly wrinkled; exteriorly light orange brown, interiorly nearly whitish; odor slight, but peculiar; taste sweetish, bitter, acrid. Contains from 4 to 5 per cent, of resin, called " resin of podophyllum," or " podophyllin," and consisting of various substances. It is purgative. Dose. — Powder, 8 to 30 grains; Abstract, 3 to 10 grains; Extract, I to 4 grains; Fluid Extract, 8 to 20 minims; Resin, 1-6 to ]/ 2 grain. 1152. Rheum. Rhubarb. From Rheum officinale (Polygonacetz) . Thibet and China. Large, thick pieces of various shapes and sizes, deprived of the outer layer, exteriorly smooth, reddish-brown, covered with a light yellowish- brown powder; interiorly of an irregularly marbled appearance, orange- yellow and white veins, striae, or rays alternating; odor peculiar, taste bitterish, somewhat astringent; when chewed, rhubarb is g.'itty from crystals of calcium oxalate. Active principles. — Several resinous cathartic principles are contained in rhubarb. Among these are: Chrysophan, chrysophanic acid, cathartin, tmodin. Has a cathartic effect, followed by an astringent action due to rheo-tannic acid. Preparations and dosee. — Powder, 10 to 30 grs.; Extract, 5 to 15 grs.; Fluid Extract, % to 1% fluidrachms; Compound Powder, 15 to 60 grs.; Syrup, 1 to 4 fluidrachms; Aromatic Syrup, 1 to 2 fluidrachms; Tincture, Aromatic Tincture and Sweet Tincture, each 1 to 6 fluidrachms; Wine, 1 to 4 fluidrachms. 1153. Sanguinaria. Bloodroot. The rhizome of Sanguinaria canadensis (Papaveracece). The United States. About two inches long, cylindrical, tapering somewhat at the ends, about Y^ inch or more thick, somewhat wrinkled; brown-red; fracture short; taste bitter, extremely acrid. Contains the acrid, narcotic alkaloid sanguinarine. Used as an expectorant. Dose. — Vinegar, 10 to 30 minims; Fluid Extract, 5 to 15 minims; Tinct- ure, 10 to 60 minims. 1154. Sarsaparilla. Sarsaparilla. From Smilax officinalis, S. medica, and other species of Smilax (Smilacece). Mexico, and Central and South America. 35 2 ABOUT DRUGS. About y z inch thick, very long, cylindrical, deeply wrinkled lengthwise, grayish-brown or orange-brown ; interiorly starchy, somewhat horny ; odor very faint ; taste mucilaginous, bitterish, acrid. The knotty rhizome or "chump," if present, should be removed. Contains the acrid principle saponin, also called "parillin," or " sarsa- parillin." Alterative. Preparations. — Fluid Extract, Compound Fluid Extract, Compound Syrup and Compound Decoction. 1155. Scilla. Squill. The bulb of Urginea Scilla (Li Hoc e a). Mediterranean coasts. Slices about 2 inches long, % inch thick, yellowish-white, or reddish- white, slightly translucent, brittle when dry, tough and flexible when damp; inodorous ; taste mucilaginous, bitter, acrid. Contains several acrid substances of which the most important are scillitoxin, scillipicrin, and scillin. Squill also contains much mucilage. Diuretic and expectorant. Dose. — Vinegar, 10 to 30 minim ; Fluid Extract, 3 to 15 minutes ; Syrup and Compound Syrup, 30 to 60 minims ; Tincture, 8 to 30 minims. 1 156. Senega. Seneka Snakeroot. From Poly gala Senega (Polygalacece). Middle and Southern United States. About 4 inches long, with a knotty crown, branched, spindle-shaped, somewhat tortuous, with a keel running spirally from crown to apex;' Exteriorly wrinkled lengthwise, slight yellowish-brown or yellowish-gray; bark thick; odor slight, but peculiar, disagreeable; taste first insipid, sweetish, afterwards acrid. Contains the acrid principle saponin, which is also called " senegin," "polygalic acid," etc. Expectorant and diuretic. Dose. — Abstract, 3 to 12 grains ; Fluid Extract, 8 to 20 minims ; Syrup, 1 to 2 fluid drachms. 1 157. Serpentaria. Virginia Snakeroot. From Aristolochia Serpentaria (Aristolochiacece). The Middle and Southern United States. Rhizome about one inch long, with remnants of stems on the upper and rootlets on the under side; rootlets long, slender, brittle; dull brown, interiorly lighter; odor aromatic, camphoraceous, terebinthinate; taste warm, bitterish, resinous. ABOUT DRUGS. 353 Contains volatile oil and resin. Aromatic stimulant tonic. Dose. — Fluid Extract, 30 to 60 minims; Tincture, ^ to 2 fluidrachms. 1158. Spigelia. Pinkroot. From Spigelia marylandica (Loganiacece). The United States. Rhizome about 2 inches long and ]/% inch thick; scars above, and numerous thin, brittle rootlets below; dark brown; slightly aromatic, bitter. Contains a bitter principle, volatile oil and resin. Anthelmintic. Dose of Fluid Extract, 30 to 60 minims. 1159. Stillingia. Queen's Root. From Stillingia sylvatica {Euphorbiacea). Southern United States. Long pieces, about 2 inches thick, wrinkled, tough, grayish-brown; bark thick with numerous resin cells; odor disagreeable; taste bitter, acrid. Contains a soft, pungent, acrid resin. Alterative. Dose of Fluid Extract, 1 to 2 fluidrachms. 1 160. Taraxacum. Dandelion. From Taraxacum De?is-leonis (Cotnpositce). Europe and America. About 3 to 6 inches long, x / 2 to 1 inch thick, branched head, wrinkled lengthwise, exteriorly dark brown when old, lighter when recently dried, interiorly yellowish, bark thick and white, with milk-vessels in concentric rings; inodorous, bitter. Contains the bitter principle iaraxacin and acrid taraxacain. Tonic, diuretic. Dose. — Extract, 15 to 40 grs.; Fluid Extract, 1 to 3 fluidrachms. 1161. Valeriana. — Valerian. From Valeriana officinalis (Valerianacece). Europe. Vermont. Rhizome about ^to 1^ inches long, brown, interiorly lighter; rootlets numerous, slender, brittle, brown, with thick bark; odor strong, peculiar, disagreeable; taste bitter, aromatic, nauseous. Contains valeric acid, volatile oil and resin. When fresh it contains much volatile oil and little valeric acid: as the drug becomes older the proportion of acid increases and the volatile oil diminishes. Antispasmodic. 354 ABOUT DRUGS. Dose. — Abstract, 8 to 30 grains; Extract, 10 to 40 grs.; Fluid Extract, % to 2% fluidrachms; Tincture, and Ammoniated Tincture, 1 to 4 fluidrachms. 1162. Veratrum Viride. American Hellebore. From Veratrum viride. (Melanthacece). Northern United States. Rhizome about 2 to 3 inches long, 1 to 2 inches thick, exteriorly blackish- gray, interiorly grayish-white; numerous light brown rootlets, from 4 to 6 inches long and about ^ inch thick; inodorous; powder extremely irritating, sternutatory; taste bitter, very acrid. Active principles. — The acrid alkaloids jervine, veratroidine ; rubijei-vine, and pseudojervine. Cardiac sedative. Dose. — Fluid Extract, 2 to 5 minims; Tincture, 3 to 10 minims. 1163. Zingiber. Ginger. From Zingiber officinale {Zingiberacece). Tropical Asia (Cochin) and the West Indies (Jamaica). Rhizomes about x / 2 inch or more broad, flattish, lobed or branched; deprived of the epidermis; pale buff -colored; fracture fibrous, starchy, show- ing scattered resin cells; odor peculiar, aromatic, pungent; taste hot, spicy. Contains volatile oil and resin. Carminative. Dose. — Fluid Extract, 4 to 30 minims; Oleoresin, 1 to 3 drops; Syrup, 1 to 2 fluidrachms; Tincture, 30 to 60 minims. CHAPTER LXV. WOODS, BARKS, ETC. 1164. Guaiaci Lignum. Guaiac wood. The heart wood of Guaiacum officinale (Zygophyllacece) . West Indies and South America. Heavy, hard, dark greenish-brown, resinous; when heated it emits a resinous odor; taste somewhat acrid. Contains about 25 per cent, resin. Alterative. Used in the preparations called Compound Decoction and Compound Syrup of Sarsaparilla. ABOUT DRUGS. 355 1 165. Haematoxylon. Logwood. The heartwood of Hcematoxylon campechianum^Legumijiosoz). Tropical America. Heavy, hard, brown-red; odor faint, peculiar; taste sweetish, astringent; colors the saliva dark reddish-pink. Contains tannin, and a crystallizable, sweet substance called hcemotoxylin. The tannin is the valuable constituent. Astringent. Dose of the Extract, about 10 grains. 1 166. Quassia. Quassia. The wood of Picrcena excelsa (Simarubacece). West Indies. Yellowish-white chips or raspings; inodorous; intensely bitter. Contains the bitter neutral principle quassiin. No tannin is contained in it. Bitter stomachic tonic. Dose. — Extract, 1 to 2 grs.; Fluid Extract, 30 to 60 minims; Tincture, 1 to 2 fiuidrachms. 1167. Aspidosperma. Quebracho Bark. From Aspidosperma Quebracho (Apocynaceoz). Brazil. Large pieces, about j{ inch thick, more or less curved, the rough corky layer and the inner bark being of about equal thickness; outer bark fissured, gray; inner bark fawn-colored; fracture fibrous; inodorous; inner bark (active portion) very bitter. Active principles: — Several alkaloids, the most important of which are mpidospertnine and quebrachine. Dose of Fluid Extract, 15 to 45 minims. 1168. Aurantii Amari Cortex. Bitter Orange Peel. The rind of the fruit of Citrus vulgaris ^Aurantiacece). Southern Europe. Thin, spiral bands or oval, curved pieces, greenish-gray and reddish on the outer surface, white on the inner side. Odor agreeable, aromatic; taste aromatic, bitter. Constituents. — The bitter principle kesperidin and a little volatile oil. (This volatile oil is known in commerce as "essence de bigarade.") Used as an aromatic, bitter, stomachic tonic. Dose. — Fluid extract, 30 to 60 minims; tincture, 1 to 2 fluid drachms. H69. Cinchona. Cinchona Bark. The bark of any species of Cinchona (Rubiacece), containing at least three per cent, of total alkaloids. 356 ABOUT DRUGS. Cinchona Flava. Yellow Cinchona; Calisaya Bark; Yellow Peruvian Bark. The trunk bark of Cinchona Calisaya. Peru an (^Bolivia. Cultivated in India. Cinchona Rubra. Red Cinchona; Red Peruvian Bark. From Ci?ichona Succirubra. Ecuador. Cultivated in Java, Ceylon, etc. The Pharmacopoeia recognizes under the general title of "Cinchona" any cinchona bark containing at least 3 per cent. of the total cinchona alkaloids; it requires the "yellow cin- chona " and "red cinchona" to contain at least 2 percent, of the alkaloid quinine, without reference to the other cinchona alkaloids. Yellow Cinchona occurs in flat pieces or quills of various sizes, of a light yellowish-brown color; inodorous; taste bitter. Dose. — Extract, 10 to 30 grains; Fluid extract, 15 to 50 minims; Infusion, 6 to 24 fluidrachms; Tincture, y z to 2 fluidrachms. Red Cinchona occurs in quills, irregular nieces, or in shavings; dark brown red; odor faint; taste bitter, astringent. Dose. — Fluid Extract, 15 to 60 minims; Comp. Tincture, ^ to 2 fluid drachms. Constituents. — Both yellow and red cinchona contain the alkaloids quinine, quinidine, cinchonine and cinchonidine; but yellow bark contains a greater proportion of quinine than the red bark, while red cinchona contains a greater proportion of cinchonidine and cinchonine. Both barks contain a peculiar tannin called cinchotannic acid. The red bark contains also a resin- ous coloring matter called cinchona red. Uses. — Cinchona is a valuable bitter tonic and antiperiodic, it is also astringent. 1170. Cinnamomum. Cinnamon. — Saigon Cinnamon. The inner bark of the shoots of some species of Cinnamomum (Lauracece). Grown in China. Saigon cinna?non occurs in regular quills, from \ to nearly 1 inch in diameter, exteriorly rough, brownish-gray, light brown on the inner side; odor very fragrant, taste sweetish, aromatic, quite pungent, but agreeable. Ceylon cinnamon is in long, slender multiple quills, consisting of the thin, smooth inner bark; of a light yellowish-brown color. It is of very fine flavor. ABOUT DRUGS. 357 Chinese cassia cinnamon is thicker than Ceylon cinnamon, occurs in single quills of much thicker bark, darker brown, and of inferior flavor. Contains volatile oil. Used as an aromatic stimulant and as flavoring ingredient. 1171. Frangula. Buckthorn Bark. From Rhamnus Frangula {Rhamnacece). Must have been col- lected at least one year before being used. Throughout Europe. Quills or troughs about i to f inch in diameter, the bark about 1-24 in. thick, brittle. Outer surface smoothish, grayish or brown; inner surface smooth, orange or brownish-yellow. Odor faint but peculiar; taste sweetish, bitter, disagreeable. Colors the saliva yellow. Constituents. — Frangulin, or rhamnoxanthin, which is cathartic; also several other laxative and cathartic principles of a resinous character. Old bark contains emodin, which is also found in rhubarb. Purgative. Dose of the Fluid Extract, 1 to 3 fluidrachms. 1172. Gossypii Radicis Cortex. Cotton Root Bark. The bark of the root of the cotton plants, Gossypium herbaceum and other species of Gossypium (ATalvacece). Southern United States. Long, thin, flexible strips, brownish-yellow exteriorly, inner surface whitish; tough, fibrous; inodorous; taste somewhat acrid. Contains resin, tannin, and red coloring matter. Its medicinal properties and uses are similar to those of ergot. Dose of the Fluid Extract, 30 to 60 minims. 1173. Granatum. Pomegranate Root Bark. The bark of the root of Punica Granatum (Granatacetz.) Cultivated in subtropical countries as on the Mediterranean borders. Troughs, quills, or fragments of various sizes, mostly in pieces about two to four inches long, bark about 1-24 inch thick; outer surface yellowish-gray or brownish-gray; inner surface lighter grayish-yellow; inodorous; taste astringent, somewhat bitter. Colors the saliva yellow. Contains the alkaloid pelletierine, and other alkaloids have also been reported as found in this drug. It is anthelmintic or taenicide. Dose of the Fluid Extract, 30 to 80 minims. 1174. Mezereum. Mezereum. From Daphne Mezereum and other species of Daphne (Thymel- acece) . 358 ABOUT DRUGS. Mountain regions of Northern Europe and Asia. Long, thin, tough bands, exteriorly brownish-yellow and light greenish, on the inner side whitish, shining. Inodorous: extremely acrid. Contains soft, acrid resin, and an acrid volatile oil, besides the bitter prin- ciple daphnin. Preparations. — Extract, Fluid Extract and Ointment: used external stimulants and rubefacients. 1175. Prunus Virginiana. Wild Cherry. From Prunus scroti na {Rosacea). The United States. Wild Cherry Bark is collected in the autumn from medium large branches of sound, not too old, trees. The bark from small branches as well as cork- covered old bark, must not be used. Curved or fiat, irregularly-shaped pieces at least 1-12 inch thick, exte- riorly greenish-brown or yellowish-brown, more or less glossy, with trans- verse scars; inner surface light brown, sometimes striate or fissured. When dry it has a faint tan bark odor; when moistened it develops a decided odor of bitter almond. Taste astringent, bitter-almond like, and bitter. Contains tannin, amygdalitis emulsin, some resin, and the bitter principle prunin. When macerated with water the amygdalin decomposes and yields hydrocyanic acid and a volatile oil similar to that produced from bitter almond. It is a bitter tonic and slightly sedative. Mostly used for its agreeable flavor. Dose. — Fluid Ex:ract. 30 to 60 minims: Infusion. 1 to 3 fluid ounces; Syrup, about y z fl. oz. 1 176. Quercus Alba. White Oak Bark. From Quercus alba (Cufiulifenz). The United States. Flattish pieces, about }{ inch thick, with corky layer removed; pale brown; with short ridges lengthwise on the inner surface: coarse fibrous fracture. A faint tan bark odor: taste very astringent. Usually coarsely ground. Contains tannin, called quercitannic acid, from 6 to 15 per cent. Used as an astringent. 1177. Rhamnus Purshiana. Cascara Sagrada. The bark of Rhamnus Purshiana [Rhamnaceee). Rocky mountains and the Pacific slope. Thin, brittle troughs or quills of various lengths, externally brownish-gray- in younger bark, the brown is mettled with nearly black alternating with ABOUT DRUGS. 359 whitish or ash-colored spots; yellowish-brown or orange-yellow on the inner side. Odor faint; taste bitter, disagreeable. Constituents similar to those of Frangula (1171). Purgative. Dose of Fluid Extract, 15 to 60 minims. 1178. Rubus. Blackberry Root Bark. The bark of the root of Rubus villosus and Rubus trivialis (Ros- acea). The United States. Quills, troughs, or flexible bands, externally blackish-gray, inner surface light-brownish; inodorous, astringent, bitter. Contains tannin and is used as an Astringent. Dose of Fluid Extract, 1 to 2 fl. drs. 1 179. Sassafras. Sassafras Bark. The root bark of Sassafras officinalis (Lauraceae). The United States and Canada. Irregular pieces deprived of the corky layer, bright rust brown, soft, brit- tle, with short fracture. Odor strongly aromatic; taste sweetish, aromatic, somewhat astringent. Contains about 3 per cent, volatile oil, some resin, and a little tannin. Used mainly as a flavoring constituent. 1180. Ulmus. Slippery Elm Bark. The inner bark of Ulmus fulva (Urticacece.) The United States. Flat pieces, about }i inch thick, tough, pale brownish-white, fracture fibrous; odor faint, peculiar; taste insipid, mucilaginous. Contains mucilage. Demulcent. 1181. Galla. Nutgall. Excrescent growths upon the bark of Quercus lusitanica, var. infectoria (Cupuliferce) caused by the punctures and deposits of ova made by the insect Cyuips Galla tinctorial. The Levant. Subglobular, about 1+ inch in diameter, tuberculated above; heavy, hard, dark olive-green or blackish-gray; fracture granular, grayish; nearly inodor- ous; taste, strongly astringent. Contains from 40 to 70 per cent, tannin, and 2 to 3 per cent, gallic acid. Powerfully astringent. 360 ABOUT DRUGS. CHAPTER LXVI. HERBS, FLOWERS, AND LEAVES. 1 182. Cannabis Indica. Indian Cannabis or Indian Hemp. Flowering tops of the female plant of Cannabis sativa ( Urti- cacece), grown in the East Indies. Branching, brittle, with small linear lanceolate leaflets, small pistillate flowers, and occasionally some hemp seed, the whole top resinous and sticky when warmed in the hand. Color greenish-brown; odor peculiar aromatic, narcotic; taste slightly acrid. Contains resin and volatile oil. Intoxicant. Hypnotic. Dose. — Extract, 3.6 to y 2 gr.; Fluid Extract, 2 to 5 minims; Tincture, 8 to 30 minims. 1183. Eupatorium. Boneset. The leaves and flowering tops of Eupatorium perfoliatu?n (Composite?). North America. Leaves opposite, united at the base, lanceolate, 4 to 6 inches long, rough on the upper side, downy beneath; flowers numerous, in corymbs, florets white; odor aromatic; taste bitter, astringent. Contains volatile oil, the bitter eupatorin. and a little tannin. Emetic, diaphoretic. Dose of Fluid Extract, 15 to 60 minims. 1184. Grindelia. Grindelia Robusta. Flowering tops and leaves of Grindelia robusta (Compositce). West of the Rocky Mountains, especially in California. Leaves about two inches long, narrow, pale green, brittle; heads many- flowered, about one-half to three-fourth inches in diameter; flowers yellow, the whole top resinous; odor aromatic: taste pungent, aromatic, bitter. Contains volatile, oil and resin. Stimulant, diuretic. Dose of Fluid Extract, 30 to 60 minims. 1185. Lobelia. Indian Tobacco. Leaves and tops of Lobelia inflata (Lobeliacece), collected after a portion of the capsules have become inflated. The United States. ABOUT DRUGS. 361 Leaves alternate, oblong, about two inches long, pale green; flowers pale "blue; odor slight; taste acrid, nauseating. Active principle, the volatile alkaloid lobeline. Emetic, powerfully depressant, narcotic. Dose. — Vinegar of Lobelia, 15 to 60 minims; Fluid Extract, 3 to 30 minims; Tincture, 10 to 45 minims. Much smaller doses are given when the drug is used as an expectorant. 1186. Marrubium. Hoarhound. The leaves and tops of Marrubium vulgare (Labiatce). Europe and America. Leaves about one inch long, opposite, ovate, obtuse, downy above, hairy beneath, flowers white in whorls; odor slight, herbaceous; taste bitter, aromatic. 1187. Mentha Piperita. Peppermint. The leaves and tops of Mentha piperita (Labiatce). Cultivated in North America and Europe. Leaves about 2 inches long, pointed, stems quadrangular, flowers small, purplish; odor peculiar, aromatic; taste pungent and cooling. Contains volatile oil. Stimulant. 1188. Anthemis. Chamomile. The flower-heads of Anthemis nobilis (Composites), from culti- vated plants. Cultivated in Europe. Subglobular, about ^ inch broad, florets white; odor aromatic, peculiar. taste aromatic, bitter. Contains volatile oil. Stimulant. 1189. Arnicae Flores. Arnica Flowers. The flower-heads of Arnica montana (Composite). Europe and North America. About i| inches broad, florets yellow, pappus hairy; odor feeble, aro- matic; taste bitter, acrid. Contains volatile oil. Used only externally. 1190. Brayera. Koosso. The female inflorescence of Brayera anthelmintica (Rosacea). Abyssinia . Clusters of panicles of reddish flowers; odor feeble, tea-like, reminding of elder flowers; taste bitter, disagreeable, acrid. 362 ABOUT DRUGS. Contains the bitter resinous principle Koossin. Anthelmintic. Dose. — Powder, 2 to 4 drachms; Fluid Extract, 1 to 4 fluid drachms; Infu- sion, one pint. 1191. Caryophyllus. Cloves. The unexpanded flowers of Eugenia caryophyllata (Myrtacece) Africa. A little over y z inch long, consisting of a calyx mounted by four spread- ing sepals, surrounding the four petals which overlap each other forming a globular bud about A inch in diameter; color, rich brown; odor, strongly aromatic; taste, aromatic, pungent. Volatile oil exudes when the clove is scratched or indented by the nail. Contains from 15 to 20 per cent, volatile oil, which is the most valuable constituent. Aromatic and stimulant. 1 192. Crocus. Saffron. The stigmas of Crocus sativus (Iridacea). Austria, Spain, France, Italy, etc. Separate, or three together attached to a portion of the style; the stigmas are thread-like, about 1% inch long, flattened and notched at the top, soft, flexible, of a rich orange brown color; odor, decided, peculiar, agreeable, aro- matic; taste, aromatic, bitterish. Colors the saliva a deep golden-yellow. Contains volatile oil as its most important constituent. Used as a flavoring ingredient and a coloring agent, but is stimulant and diuretic. Dose of the Tincture, 1 to 2 fluid drachms. 1 193. Lavandula. Lavender. The flowers of Lavandula vera (Labiatce). Cultivated in Europe. Small, with tubular blue-gray calyx, violet-blue corolla; odor fragrant: taste bitterish, aromatic. Contains volatile oil. Stimulant, used mainly as an aromatizing ingredient. 1 195. Rosa Gallica. Red Rose. The petals of Rosa gallica (Rosacea), collected just before the expansion of the roses. Cultivated in France. Roundish, deep purplish red petals of a rose-like fragrance; taste, bitter- ish, slightly acidulous, somewhat astringent. Contains a very small amount of volatile oil and a little tannin. Used as a mild astringent for children. ABOUT DRUGS. 365 1104. Matricaria. German Ckamcvili. The never r.e^is ::' .*/ .".: _".- r.::.-..? 1. Eurcpe. Ar:_: - :r. :r. :r:a: rar--;re:s — i::e. f.~ — er= yell;-*-: :i;r arena::: taste, bitter, strongly aromatic Contains volatile oil. Used as a diaphoretic and stomachic. 1 196. Sambucus. E:~ir Floti?.;. The f. :■ '.vers ::' i".:";h'. .":. : .-.: ?.:-": ■::.■: T.:r *•;'-".'. ';'.:. v..? . North America. 5~a... :rea~-::' irei :: pale ye..:- :ie: ,.;;_'.. a: ar:~at:: :as:e erish arena::: 5:rr.e r.^.: ::::e: Contains -volatile oil and a little acrid resin 5::rr.U-ar: ar. e ::apr.:re:::. 1197. Santonica. Levantic Wormseed, or Germ an Worm- The unexpanded flower-heads of Artemisia maritima {Com- positce). Turkestan. arly -fV inch long, ovoid, grayish-green: odor strong, peculiar; taste aromatic, bitter. Con"a:r.£ the pe: itt'z'.y a::i pr:r:::ple .-'.-:.>;:».- are. s:~e r:'.a::'.e ::'. ar 1 res r Anthelmintic. 1198. Belladonnas Folia. Eiiiai::;na Liavis.— Frcm A:-\ r.z -?:■.".".:-'."'."■'.•■- • o.. ".::.:.:.: . Central and southern Europe. Four to 6 inches long, broadly ovate, tapering, smooth, thin, brownish- rreer a"::ve gray:;r. greer. zer.ea;.r. :i:r :a:r: r7::a:e:_s :as:e "e:::er;si ■_:.: easar: Active principles.— T'-^ - ar.d rial : anodyne.:: 35 Dose. — Extract, \ to \ grain Fluid Extract .: 5 rr.:r.:rr.= Tinctnie 15 to 30 minims. Poisonous Effects :r.r. Antidotes.— See 1:5 = 1109. Buchu. Buchu Leaves. — From Barosma betulina.B, crcnulata, and B. serntifolia {Rut inch long, flattened, wrinkled, hard, brownish-black, interiorly whitish, oily; inodorous when whole, but emitting a disagreeable odor when bruised; taste bitter. Contains the alkaloids atropine and hyoscy amine; also fixed oils. Mydriatic anodyne. Dose. — Extract, about \ grain; Fluid Extract, 1 to 3 minims; Tincture, 8 to 30 minims. It is also used externally in the form of ointment. 374 ABOUT DRUGS. CHAPTER LXVIII. MISCELLANEOUS CRUDE PLANT DRUGS. Chondrus and Ergot. 1237. Chondrus. Irish Moss; Carrageen. Consists of Chondrus crispus and C. mamillosus (A/gce). Tough, translucent, pale yellowish-white, branched; soft, slippery, carti- laginous-looking when put in water; boiled with from 20 to 30 parts of water r it forms, on cooling, a jelly of a mucilaginous taste and a distinct sea-weed odor. Contains pectin Demulcent. 1238. Ergota. Ergot; Secale Cornutum. The sclerotium (compact spawn) or middle (second) stage of development of the fungus Claviceps purpurea {Fungi), which grows within the flower of the common rye, taking the place of the grain. Southern Europe, especially Spain and Southern Russia. Grain-like bodies about 1 to 2 inches long, | to \ inch thick, nearly trian- gular, somewhat curved, marked lengthwise by three grooves, that on the inner side of the curve being most distinct; thickest about the middle, taper- ing gradually toward both ends, which are blunt; externally dark purplish, with a slight cloudy, bluish bloom; plump, firm, somewhat elastic but easily- broken; fracture even, whitish toward the center but pinkish toward the cir- cumference; fissured when old; odor peculiar, heavy, disagreeable; taste, greasy, mawkish, nauseous. When ergot is triturated with solution of potassium hydrate, a strong odor resembling that of herring brine (from trimethylamine) is developed. Contains, according to Dragendorff and Podwissotzky, scleretic acid, scleromucin and sclererythrin , all of which are brown amorphous powders hav- ing the medicinal properties of the ergot. Kobert produced the alkaloid comutine from ergot; this, also, has the active properties of the drug in a high degree. Ergot also contains 30 per cent, of fixed oil. Uses. — Ergot is a motor excitant and causes contraction of the unstriped or involuntary muscular fibres, as of the uterus, sphincters and arterioles. Dose. — Powder, 15 grains to 1 ounce; Extract, 5 to 10 grains; Fluid Extract, 1 to 16 fluid drachms. ABOUT DRUGS. 375 Extract-like Drugs. 1239. Aloe. Aloes; Socotrine Aloes. The inspissated juice of the leaves of Aloe socotrina (Liliacece). Eastern Africa and islands in the Indian Ocean. Reddish-brown or orange-brown mosses, with a somewhat resinous, dull, opaque, conchoidal fracture; in quite thin fragments it is translucent, with a garnet-red or brownish-red color; the powder is yellowish-brown. Soluble in four times its weight of boiling water. It exhibits numerous crystals of aloin when mixed with alcohol and then examined under the microscope. Odor, saffron-like, fragrant, intensified when the aloes is breathed upon. Taste, extremely bitter. Contains the bitter, purgative, resinous, neutral principle aloin and also a minute amount of volatile oil. Properties. — Purgative; in smaller doses, laxative; in minute doses, a bitter, stomachic tonic. Preparations and Doses. — Purified Aloes, in powder, as a tonic, 1 to 2 grs.; laxative, 2 to 5 grs.; purgative, 5 to 15 grs. Extract, ]/ 2 to 5 grs.; Tinc- ture, 1 to 4 fluid drachms; Wine, about 4 fl. drs. 1240. Catechu. Catechu; Cutch. An extract prepared from the wood of Acacia Catechu (Legu- minosce). Pegu, and most parts of India and Burmah. Dark-brown, brittle, irregular masses, somewhat glossy when freshly broken; soluble in water and in diluted alcohol; nearly inodorous; of strongly astringent, sweetish taste. Contains catechu-tannic acid and catechin. Astringent. Dose. — Powder, 1 to 30 grains; Compound Tincture, 10 to 60 minims. 1241. Guarana. Guarana. A dried paste prepared from the seeds of Paullinia sorbilis (SapindacecE). Brazil. Cylindrical sticks, sometimes flattened, about 6 inches long and 1 inch in diameter, hard, externally dark-red brown, usually comparatively smooth, fracture uneven, coarsely granular, yet somewhat glossy, much lighter than the exterior. Odor, feeble, but peculiar, somewhat chocolate-like; taste, bit- ter, astringent. Guarana is partially soluble in alcohol, and also in water, the solutions being brown. 37^ ABOUT DRUGS. Constituents. — The alkaloid gnaranine (probably identical with theine), and a large percentage of tannin. Properties. — Guarana resembles tea and coffee in its action, being a car- diac stimulant. Dose. — Powder, 10 to 60 grains; Fluid Extract, 10 to 60 minims. 1242. Kino. Kino. The inspissated juice of Pterocarpus Marsupium (Leguminosee). India. Small, irregular, brittle, shining, dark, brown-red fragments, ruby-red and transparent in thin splinters. Colors the saliva deep-red; scarcely at all soluble in cold water, but almost entirely soluble in diluted alcohol; nearly insoluble in ether. Inodorous; very astringent, sweetish. Contains kino-tannic acid. Astringent. Dose. — Powder, 10 to 20 grains; Tincture, x / z to 2 fluid drachms. 1243. Lactucarium. Lactucarium. The hardened milk-juice of Lactuca virosa (Composites). Europe In pieces showing the form of the vessel in which the juice was collected to harden. Often broken into irregular fragments. Exteriorly grayish-brown or dull reddish-brown, interiorly whitish or yellowish, waxy. Odor heavy, reminding somewhat of opium; taste, strongly bitter. Partially soluble in alcohol and ether; yields a turbid mixture when tritu- rated with water. Contains bitter lactucin, which is its only important constituent. Anodyne, soporific, hypnotic. Dose. — 8 to 30 grains; Fluid Extract, 5 to 30 minims; syrup, 2 to 3 fluid drachms. 1244. Opium. Opium. The concreted, milky exudation obtained in Asia Minor by- wounding the unripe capsules of Papaver som?iiferum (Papaver- aeeee) y and yielding in its normal soft condition not less than 9 per cent, of the alkaloid morphine when assayed by the official process. Powdered Opium, which is opium dried at not over 85. ° C. (185. ° F.) and reduced to No. 50 powder, is required to yield not less than 12, nor more than 16, per cent, of morphine. Crude opium, or whole opium, occurs in irregular sub-globular or flattened masses, with remains of poppy leaves and rumex seeds adhering to the sur- ABOUT DRUGS. 377 face; moist enough to be soft or plastic, or so dry as not to flatten out when lying on a flat support. It is dark-brown, somewhat glossy when dry. The odor is peculiar, narcotic, nauseous; taste, bitter, disagreeable. When dried the normal opium, or "lump opium," as imported, loses from ten to twenty per cent, of moisture. When opium is dried at about 105 C. ( 221° F.) and then weighed and afterwards exhausted with cold water, the liquid water extracts being evapo- rated to dryness, the dry extract obtained should amount to from 55 to 60 per cent, of the weight of the dried opium taken. Whole opium is used for making powdered opium and extract of opium, but all other opium preparations must be made from dry " powdered opium." Active Principles. — The alkaloids morphine and codeine are the most valuable. Properties. — Opium is a hypnotic. It is a powerful narcotic, often employed to relieve pain as well as to produce sleep, etc. Dose. — Powders, about 1 grain; Extract, about ]/ 2 grain; Tinctures, about 10 minims; Vinegar, 5 to 10 minims; Wine, about 10 minims. Compound Preparations. — Troches of Glycyrrhiza and Opium; Powder of Ipecac and Opium, or Dover's Powder, of which the adult dose is about 10 grains; Tincture of Ipecac and Opium, about 10 minims; Camphorated Tinc- ture of Opium, of which the dose is about 2 to 4 fluid drachms. A Plaster of Opium is also official. Denarcotized Opium and Deodorized Tincture of Opium are contained in the Pharmacopoeia. They are comparatively free from the alkaloid narco- tine, which is considered an objectionable constituent, and from the nauseous odor. Pills of Opium are also official. All opium preparations of the United States Pharmacopoeia, for internal use, are of 10 per cent, strength, w'ith the sole exception of the Camphorated Tincture of Opium (" Paregoric "). Poisonous Effects. — Drowsiness, profound lethargy, breathing labored, slow and stertorous; face dusky and swollen; pupils contracted; heart's action slow and feeble; total relaxation, coma, death from paralysis of the respiratory muscles. Antidotes. — Prompt evacuation of the stomach by emetics or the stom- ach pump; then the patient should be compelled, if possible, to walk about, and the enforced exercise kept up; external stimulation, by rubbing, etc.; alcoholic stimulants, strong coffee; artificial respiration, if possible; and the administration of belladonna or atropine, or subcutaneous injections of atro- pine. • 378 ABOUT DRUGS. CHAPTER LXIX. STARCHES. GUMS AND SUGARS. 1245. Amylum. Starch. Wheat Starch. The fecula or starch of the seed of Triticui?i vulgar e (Gramin- acea),or wheat. Manufactured in all countries from cultivated wheat. Irregular, angular, soft, friable, white masses; inodorous and tasteless. Insoluble in cold water, alcohol and ether. 1246. Maranta. Arrow-root. The fecula separated from the rhizome of Maranta arundina- cea (Cannacem). Bermudas, West Indies, Central and South America. Used for preparing foods for infants and invalids. 1247. Acacia. Gum Arabic The dried gummy exudation from Acacia Verek and other species of Acacia (Leguminosce). Africa. Irregularly-shaped fragments or tears, opaque from numerous tissues, glass-like in the fracture, transparent in thin pieces; nearly inodorous; taste mucilaginous, insipid. Entirely soluble in water; insoluble in alcohol. Used in powder as an emulsifying agent and as an excipient; also in the form of mucilage for the same and other similar purposes, and as a demulcent. 1248. Tragacantha. Tragacanth. The dried gummy exudation from Astragalus gummifer and other species of Astragalus (Leguminosce), Western Asia. Irregular, contorted bands, whitish, translucent, horn-like, tough, swell- ing in water to a gelatinous, sticky mass. Used as an excipient either in powder or in the form of mucilage of traga- canth. 1249. Saccharum. Sugar. The refined sugar (C^H^Ou) of Saccharum offici?iaru?n (Grami- nacece). The Pharmacopoeia defines sugar as cane-sugar, only; but most of the white sugar now consists of beet-root sugar. Sugar is soluble in about half its weight of water at 15° C; it is also- soluble in 175 parts of alcohol at 15° C, but insoluble in ether. ABOUT DRUGS. 379 1250. Saccharum Lactis. Milk Sugar. This variety of sugar (Cx2H2.2Ou.H2O) is obtained from the whey of cow's milk. Hard, crystalline, white, inodorous, sweetish, soluble in 7 times its weight of water at I5 C C. Used as a diluent in powders, triturations, and in various tablets, gran- ules, etc. 1251. Manna. Manna. The concreted saccharine exudation from Fraxinus Or?ius^ {Oh ace a). Southern Europe. Flattish, trough-shaped or three-edged pieces, friable, yellowish-white, porous crystalline; odor peculiar, sweetish; taste sweet, leaving a slightly bitter, acrid after-taste. Water-soluble, and soluble also in 15 parts of boiling alcohol. Consists mainly of mannit and glucose. Used as a mild laxative. 1252. Mel. Honey. A saccharine secretion deposited by the bee. Apis mellifica {Insccta). Syrupy, or semi-fluid and granular, pale-yellow or brownish-yellow, of a peculiar sweetish odor; very sweet, afterwards faintly acrid taste. When heated, skimmed and strained, it is called clarified honey, which is used in the prepara- tion of confection of rose, honev of rose, and in mass of carbonate of iron. CHAPTER LXX. GUM-RESINS, RESINS, AND BALSAMS. 1253. Ammoniacum. Ammoniac. A gum-resin (1123) obtained from Dorema Apimoniacinn (Um- belliferce). Persia, Turkestan. Roundish tears of various sizes rarely exceeding an inch in diameter, pale brownish-yellow exteriorly, white interiorly, brittle only when cold, fracture 5i3 ABOUT DRUGS. waxy and conchoidal; odor peculiar; taste bitter, acrid, disagreeable. Yields a milk-white emulsion when triturated with water. Contains volatile oil, resin and gum. Antispasmodic and blennorhetic. Externally a stimulant and rubefa Preparations. — Mixture of Ammoniac, and for external use the Ammoniac Plaster with or without mercury 1254. Asafoetida. Asafetida. A gum-resin obtained from the root of Ferula Narthex and F. Scorodosma \UmbdliferiE). Persia, and other countries on the Arabian Sea. Tears, exteriorly brown, interiorly white, or masses composed of such tears imbedded in a yellowish-brown soft or hard mass. When hard the tears break with a conchoidal wax} T fracture, the milk-white color of the surface of the fracture changes gradually on exposure to the air to pink and brown. O::: string garlicky, ozer.sive: taste bitter, acrid, garlicky. Wit en triturated with water it yields a nearly milk-white emulsion. At least 60 per cent, of the asafetida should be dissolved by alcohol. Contains volatile oil, resin and gum. Used as a nervine and antispasmodic, and also externally as a stimulant application in the form of plaster. Preparations. — Mixture (dose, 4 fluid drachms), Tincture lose, 30 to 60 minims), Pills of Asafetida, Pills of Aloes and Asafetida, Compound Pills :: Galbanum. Asafetida Plaster. 1255. Galbanum. Galbanum. The gum-resinous exudation from Ferula galbaniflua, and probably from other related plants ( Umbelliferce). Persia. Masses consisting of small agglutinated tears, exteriorly yellowish-brown, interitrly whitish, fracture waxy; tier ceculiar, disagreeable; taste bitter, acrid. Contains volatile :il, resin and gum. Stimulant, blennorrhetic, externally stimulant. Preparations. — Galbanum Plaster, Compound Pills of Galbanum, and in Asafetida Plaster, 1256. Cambogia. Gamboge. A gum-resin from Garcima Hanburii | Guttife^a). Siam. Cylindrical pieces, from ?+ to 2 inches in diameter, brownish orange- yellow; fracture smooth, waxy; powder bright yellow; inodorous; acrid. Triturated with water it yields a yellow emulsion. ABOUT DRUGS. $8l Contains resinous gambogic acid and gum. It is a powerful hydrago^ue cathartic (dose, 1 to 5 grains) and is contained in Compound Cathartic Pills. 1257. Myrrha. Myrrh. A gum-resin from Balscujiodendron Myrrha {Burseracece). Eastern Africa and southwestern Arabia. Irregular pieces, brownish yellow or reddish-brown, wax-like fracture, translucent with a wine-red color when in thin splinters or pieces; yields a light brownish-yellow powder; odor balsamic, peculiar; taste bitter, acrid. Triturated with water it forms a brownish-yellow emulsion. Contains volatile oil, resin and gum. It is tonic, stimulant, blennorrhetic. Slightly astringent. Dose. — Powder, S to 30 grains; Tincture, 15 to 60 minims. It is contained in Compound Iron Mixture, Pills of Aloes and Myrrh. Com. Iron Pills, Com. Pills of Galbanum, Tinct. of Aloes and Myrrh. 1258. Resina. Resix, Colophony. The resin left after distilling off the volatile oil from turpen- tine (1267). The United States. Large quantities are produced in North Carolina. Transparent, amber-colored, hard, brittle, with a glossy fracture, odor feeble terebinthinate, taste resinous. Melts at about I35 C C. (275 C F.) Soluble in alcohol, ether, volatile oils, and fixed oils; insoluble in water. Consists of abietic anhydride. Used as an ingredient in plasters, cerates, and ointments. 1259. Guaiaci Resina. Guaiac Resix. The resin of the heart wood of Guaiacum officinale (Zygop/iy/- lacecE) . West Indies and South America. Dark, greenish-brown, in large masses, nearly black, in thin splinters, translucent, brittle, fracture glassy; fusible, emitting an aromatic odor when melted; somewhat acrid to the taste. The powder is light-grayish, but becomes green on exposure to the air. Properties. — Diaphoretic, diuretic, alterative, stimulant. Dose. — Powder, S to 15 grains; Tincture and Ammoniated Tincture, 30 to 60 minims. .382 ABOUT DRUGS. 1260. Mastiche. Mastic. The hardened resinous exudation from Pistacia Lentiscus {Terebinthacece). Mediterranean countries. Globular tears, smaller than a pea, pale yellow, transparent, brittle, yielding a white powder; odor and taste resinous. Soluble in absolute ■alcohol. Used in pills of aloes and Mastic. 1261. Pix Burgundica. Burgundy Pitch. Prepared resinous exudation from Abies excelsa (Coniferce). Southern Europe. Hard at ordinary temperature, but very soft, running, when warmer, •opaque or translucent. Brittle when cold, fracture glossy; yellowish brown, somewhat aromatic. Used as an ingredient in Burgundy pitch plaster and in pitch plaster with •cantharides. 1262. Scammonium. Scammony. A hardened, resinous exudation, from the root of Convolvulus Scammonia (Convolvulacecz) . Minor Asia. Smyrna. Irregular pieces, or circular cakes, greenish-gray, porous, fracture angu- lar ; odor peculiar, somewhat cheese-like; taste slightly acrid. Consists mainly of the resin called scam?nonin. Cathartic. Dose. — Powder, 5 to 15 grains ; the official Resin of Scammony is purified Scammony; dose, 3 to 10 grains. 1263. Benzoinum. Benzoin. balsamic resin from Styrax Benzoin (Styracece). Siam, Sumatra. Resinous masses of a grayish-brown color, the exterior being darker when longer exposed, interiorly mottled, large tears or " almonds" of pure, •opaque resin being imbedded in a mass of translucent, yellowish-brown resin, the tears being milk-white in the fracture; odor agreeable, balsamic; taste faintly but gratefully aromatic. Benzoin is almost entirely solution in solution of potassa, and also in 5 parts of warm alcohol. It emits vapors of benzoic acid when heated. Contains from 15 to 20 per cent, of benzoic acid and a minute quantity of volatile oil. ABOUT DRUGS. 383 Used in external applications as a cosmetic, as a preservative of fats, and as an aromatizer. Preparations. — Benzoinated Lard, Tincture of Benzoin and Compound Tincture of Benzoin. 1264. Balsamum Peruvianum. Balsam of Peru. A thick liquid balsam obtained from Myroxylon Pereiroz {Leguminosoz). Central America. Brownish-black, lighter or reddish-brown and transparent in thin layers. Odor agreeable, balsamic, reminding of a combination of vanilla and benzoin. Taste warm, bitterish, finally acrid. Wholly soluble in 5 parts of alcohol. Contains about 6 per cent, cinnamic acid. About 30 per cent, consists of xesins; and 60 per cent, of benzyl cinnamate (cinnamein), which is an oily liquid. Uses. — Externally it is used as a cure for the itch, and it is added to ointments as a preservative. Internally it is expectorant and blennorrhetic. 1265. Balsamum Tolutanum. Balsam of Tolu. A semi-solid or solid balsamic resin obtained from Myroxylon toluifera (Legu?ninosce) . Venezuela and New Granada. Yellowish-brown, or brownish-yellow, transparent in thin layers, brittle when cold; soft at ordinary room temperatures, running when warmed; odor agreeable, balsamic; taste feeble but pleasantly aromatic. Entirely soluble in alcohol. Contains cinnamic acid, volatile oil and minute amounts of other aromatic bodies. Used as a blennorrhetic, but mainly as a pleasant addition to cough mix- tures, etc. Preparations. — Tincture and Syrup. 1266. Styrax. Storax. A balsam prepared from the inner bark of Liquidambar orientalis (Hamamelacece). Asia Minor. Tenacious, semi fluid, sticky, gray, opaque, transparent in thin layers. Odor agreeable, balsamic; taste balsamic. Entirely soluble in an equal weight of warm alcohol. Contains styrol, cinnamic acid, styracin, and other cinnamic ethers, resin, etc. Used in Compound Tincture of Benzoin. 3^4 ABOUT DRUGS. 1267 Terebinthina. Turpentine. The concreted oleoresin-from Pinus australis and other species : P h Co Kifcrez). N : rth Carolina and other southeastern portions of the United S:a:es. I e iowish, tough masses, brittle in the cold, granular interiorly; odor and :as:e :t:t'::r.\:.:r. a:e Consists of volatile oil and resin. Used as a sumaian: :r.cre tr :n some ointments and plasters. 1268. Terebinthina Canadensis. Canada Turpentine* [Balsam c f Fir.] A thick liquid oleoresin from Abies balsamea (Coniferea:). Pa.e yellowish, :r faintly greenish, transparent; odor terebinthinate; :as:e z;::er: = h. 5ligh:iv acrii. En::re".y sciu'zie in ether. :hi:r::rrm :enz:i. 1269. Pix Liquida. Tar. destructive iistillatic r c: the v-rcc ci ::' P:*:u: f.:.'u:?>-:s and :• t'other species of Pinus (Conifer a). North Carolina. Produced also in many other localities in Europe and America. Thick, viscid, blackish-brown, transparent in thin layers, granular and opaque when old; heavier than water; reaction acid; odor empyreumatic terebi d : b i : a I e taste sharp, and smoky . Soluble in alcohol. Contains oil of turpentine, acetic acid, creasote, phenol, pyrocatechin, resin, etc. The granular appearance of old tar is due to crystals of pyro- ca:e:hin. ~h::h 5 sziur'.e in water as well as alcohol, and pungent. Uses — 5 : i m a '. a n : . ': '. e n norrhetic. Also used externally in skin affections. Preparations. — Syrup ana C;n:men:. 1270. Copaiba. " Balsam of Copaiba." T;;e oleoresin "n :: a " balsam ".] ::' C:r. ::/■:>-.: Z.: •;_-.-.:'. •;-"; and other species of Copaifera (Lcguminosa). £j'.'c.Z A. A pale yellowish or brownish-yellow transparent or translucent, syrupy liquid: odor peculiar, aromatic, nauseous: taste nauseous, persistently bitter, a:: a Reaiiiy s:iu:ie in a its: hate ai:ch:i Contains : : latile oil and resin. Properties. — Expectorant, blennorrhetic, diuretic diaphoretic. Dose. — : : :•: minims ABOUT DRUGS. 385 CHAPTER LXXI. FATS AND FIXED OILS. 1271. Adeps. Lard. Hog's lard, recently rendered and refined. A soft, white, free from rancidity, of bland taste. Melts at 35° C. (95' F.) Used in preparing ointments and cerates. 1272. Cera. Wax. A peculiar solid fat deposited by the bee. Cera Flava is the natural, or yellow, wax. Cera Alba is white wax prepared by bleaching the yellow wax. Wax melts at about 64° C. (147 F.); is soluble in ether and chloroform. Used in cerates, ointments and plasters. 1273. Cetaceum. Spermaceti. A peculiar fat from Physeter marrocephalus, the sperm whale. Perfectly white, somewhat translucent in thin layers, unctuous, scaly, crystalline, inodorous, of a bland taste. Melts near 50' C. (122° P.), and con- geals at about 45 C. (113° F.) Used in cerates and ointments. 1274. Sevum. Suet. Recently rendered mutton-suet, free from rancidity. White, nearly inodorous, bland. Melts between 45^ and 50° C. (113 and 122° F.). Used in mercurial ointment. 1275. Oleum Adipis. Lard Oil. The fixed oil expressed from lard at a low temperature. Colorless or pale yellowish, nearly inodorous, bland, free from rancidity. 1276. Oleum Amygdalae Expressum. Expressed oil of Almoxd. Sweet oil of Almond. The fixed oil expressed from the Bitter and Sweet Almond. Nearly colorless, or of a pale straw color, ct a mild nutty odor and taste. Used in " cold cream" and phosphorated oil. 1277. Oleum Gossypii Seminis. Cotton Seed Oil. From the seed of Gossypium herbaceum (Malvaceae), and other species of Gossypium . Pale yellow, inodorous, bland. 1278. Oleum Lini, Flaxseed Oil. Linseed Oil. Expressed from flaxseed without the aid of heat (1231). 386 ABOUT DRUGS. A yellowish or light yellowish-brown drying oil of a mild peculiar odor and bland taste. 1279. Oleum Morrhuae. Cod Liver Oil. From the fresh livers of Gadus Morrhua and other species of Gadus (Pisces). Northeastern coasts of the United States, Newfoundland, Norway. Colorless or pale yellow, thin, of fishy odor and a bland, slightly fishy taste. 1280. Oleum Olivae. Olive Oil. Sweet Oil. From the ripe fruit of the Olive, Oka euroficza (Oleacece). France, Italy, Spain. Pale yellow; of a faint agreeable nutty odor and taste, bland. 1281. Oleum Ricini. Castor Oil. From the seed of Ricinus communis (Euphorbiacece). The United States. Italy. Colorless, or nearly so, with a pale yellowish tint, viscid, odor feeble but nauseating; taste bland but nauseating, finally slightly acrid. Soluble in an equal weight of alcohol and miscible with absolute alcohol in all proportions 1282. Oleum Sesami. Sesamum Oil. Benne Oil. From the seed of Sesamum indicum (Pedaliacece). Light yellow, inodorous or nearly so, bland. 1283. Oleum Theobromae. Oil of Theobroma. Butter of Cacao. A solid fat from the seed of Theobratna Cacao {Sterculiacea) . Mexico. Yellowish-white; odor faint but rather agreeable; taste bland, reminding somewhat of chocolate. Melts at 30° to 35 C. (86° to 95 s F.). Used for making suppositories. 1284. Oleum Tiglii. Croton Oil. From the seed of Croton Tigliutn {Euphorbiacecz). India. Yellow or brownish-yellow, slightly fluorescent; odor feeble, fatty; taste first mild, oily, then acrid, burning. Applied to the skin it vesicates. Incom- pletely soluble in alcohol, quite soluble in ether and chloroform. Used sometimes internally as a drastic cathartic. Externally as an irri- tant and suppurant. Dose one-fourth to two drops, in olive oil, or otherwise well diluted or distributed. ABOUT DRUGS. 387 CHAPTER LXXII. VOLATILE OILS AND CAMPHORS. 1285. Oleum Amygdalae Amarae. Oil of Bitter Al- mond. A volatile oil produced in bitter almond by maceration with water and obtained by subsequent distillation. Colorless or pale yellow; odor peculiar, hydrocyanic acid-like; taste bit- ter, burning. Scarcely soluble in alcohol. 1286. Oleum Anisi. Oil of Anise. From Anise (1212). Colorless or pale yellow, having the peculiar odor of anise, and a sweetish, aromatic, burning taste. Soluble in an equal weight of alcohol. Solidifies at from io° to 15 C. (50 to 59° F.). Used as a stimulant carminative, and as a flavoring agent. Oil of Star Anise resembles the true Oil of Anise but does not congeal until at about 2° C. (35. °6 F.). 1287. Oleum Aurantii Corticis. Oil of Orange Peel. Expressed from the peel of fresh sweet orange. Pale yellowish, of the characteristic odor of sweet orange; an aromatic, burning; somewhat bitter taste. Used for flavoring. 1288. Oleum Aurantii Florum. Oil of Orange Flowers. Oil of Neroli, Yellowish or brownish-yellow, of the fragrant odor of orange flowers; taste aromatic, bitterish, burning. Used in perfumery. 1289. Oleum Bergamii. Oil of Bergamot. Expressed from the rind of the fruit of Citrus Berga?nia {Aurantiacece). Pale greenish; odor very fragrant. Used in perfumery. 1290. Oleum Cari. Oil of Caraway. Distilled from Caraway (1215). Colorles-s or pale yellowish, of the peculiar odor of caraway, and a charac- teristic spicy taste. Used as a stimulant carminative and for flavoring. 388 ABOUT DRUGS. 1291. Oleum Caryophylli. Oil of Cloves. Distilled from Cloves (1.191) Light brown, or brownish-yellow, of a strong spicy odor of cloves, and burning taste. Very soluble in alcohol. 1292. Oleum Cinnamomi. Oil of Cinnamon. Pale yellowish-brown, of the strong characteristic aromatic odor of cin- namon, and a spicy, burning taste (1170). Used for flavoring. 1293. Oleum Copaibae. Oil of Copaiba. The volatile oil distilled from Copaiba. Pale yellowish, or nearly colorless, of the odor of copaiba, and a pungent, bitterish taste. Used for the same purposes as copaiba (1270). Dose. — 5 to 15 minims.' 1294. Oleum Coriandri. Oil of Coriander. Distilled from Coriander (1219). Colorless or pale yellowish, aromatic, spicy. Used for flavoring. 1295. Oleum Cubebae. Oil of Cubeb. Distilled from Cubeb (1220). Pale greenish, or greenish-yellow, of the odor of cubeb, and a hot, cam- phoraceous taste. Used for the same purposes as Cubeb (1220). Dose.— 5 to 15 minims. 1296. Oleum Eucalypti. Oil of Eucalyptus. Distilled from fresh Eucalyptus leaves (1202). Colorless or pale yellowish, of the strong, peculiar, camphoraceous odor of Eucalyptus, and a pungent, cooling taste. Used as an antiseptic. 1297. Oleum Fceniculi. Oil or Fennel. Distilled from Fennel (1221). Colorless or pale yellow, sweetish, aromatic, spicy. Used as a carminative and flavoring agent. 1298. Oleum Gaultheriae. Oil of Wintergreen. Distilled from Gaultheria. Colorless or pale yellow, or reddish-yellow, of a peculiar strong odor, and a sweetish, warm, aromatic taste. Consists mainly of methyl salicylate. Used as an antiseptic and for flavoring. ABOUT DRUGS. 389 1299. Oleum Juniperi. Oil of Juniper. Distilled from Juniper berries (1223). Colorless, or pale yellowish, of the characteristic odor of Juniper, and a warm, aromatic, sweetish, terebinthinate taste. A constituent of gin. 1300. Oleum Lavandulae. Oil of Lavender. Distilled from the flowering tops or herb of Lavender (1193). [Called in the trade "Oil of Garden Lavender."] Colorless or pale yellowish, of strong but coarse Javender odor, and a pungent, bitterish taste. Used in liniments. 1301. Oleum Lavandulae Florum. Oil of Lavender Flowers. Distilled from fresh Lavender flowers (1193). Colorless or pale yellowish, of a superior fragrant lavender odor, and a pungent, bitterish taste. Used for flavoring and in perfumery. 1302. Oleum Limonis. Oil of Lemon. Expressed from fresh lemon peel. Pale yellow, of the aromatic fragrance of lemon, and an agreeable, aromatic, pungent taste. Used for flavoring. 1303. Oleum Menthae Piperitae. Oil of Peppermint. Distilled from Peppermint (1187). Colorless or pale yellowish, having a strong odor of peppermint, and a burning, aromatic taste, producing in the mouth a cooling sensation, when air is inhaled. Its most important constituent is menthol. Used as a carminative, and for flavoring. 1304. Oleum Pimentae. Oil of Allspice. Distilled from Pimenta. Pale brownish-yellow, of the strong spicy odor, and taste of allspice. Used for flavoring. 1305. Oleum Rosae. Oil of Rose. Distilled from the fresh flowers of Rosa damascena {Rosacea). France and other Mediterranean countries. Very pale yellowish, of a powerful rose odor, and a sweetish aromatic taste. Solidifies at about io° C. (50 F ) Used for flavoring, and in perfumery. 39° ABOUT DRUGS. 1306. Oleum Rosmarini. Oil of Rosemary. Distilled from Rosemary leaves (1206). Colorless or pale yellowish, agreeably aromatic, pungent, camphoraceous. Used in liniments, and for flavoring, and is an important constituent of Cologne water. 1307. Oleum Sabinae. Oil of Savin. Distilled from Juniperus Sabina (Conifer a). Colorless, or pale yellowish, of the peculiar strong, somewhat terebinthi- nate, odor of Savin, and a burning, bitterish, camphoraceous taste. Stimulant, irritant. Dose. — About 5 drops. 1308. Oleum Sassafras. Oil of Sassafras. Distilled from Sassafras (11 79). Colorless, or pale yellowish, of the characteristic odor of Sassafras, and a warm aromatic taste. Used as a carminative and for flavoring. 1309. Oleum Sinapis Volatile. Volatile Oil of Mus- tard. A volatile oil produced by the maceration of black mustard with water, and obtained by subsequent distillation (1235). Colorless, or pale yellowish, extremely offensive, pungent, acrid. Used as a rubefacient in liniments. 1310. Oleum Terebinthinae. Oil of Turpentine. The volatile oil distilled from Turpentine (1267). Colorless, thin, of a characteristic odor, and burning taste. Used in liniments. It is also stimulant, diuretic, anthelmintic and pur- gative. Dose. — As a stimulant, 5 to 15 minims. 131 1. Camphora. Camphor. A stearopten (C 10 H 16 O) derived from Cinnamomum Ca?nphora (Lauracece). China, Japan, Formosa. White, translucent, in thin fragments perfectly transparent, tough, crys- talline, readily pulverizable when moistened with alcohol, ether or chloroform. Odor characteristic, penetrating; taste pungent. Melts at 175 C. (347° F.), .boils at 205 C. (401° F.), and sublimes without residue. Is readily ignited, ABOUT DRUGS. 391 and burns with a smoky flame. Entirely and readily soluble in alcohol, ether, chloroform, volatile oils, fixed oils. Properties. — Stimulant of brain and circulation. Prophylactic and anti- septic. Diaphoretic. Dose. — 1 to 5 grains. Preparations. — Camphor Water, Spirit of Camphor, Cerate and Lini- ment. 1312. Menthol. Menthol. The stearopten from oil of peppermint. In small white or transparent slender, prismatic crystals having the com- position CioH 20 0. Odor of peppermint; taste pungent, afterwards cooling. Readily soluble in alcohol and ether. Properties. — Stimulant, antiseptic, anti-neuralgic. CHAPTER LXXIII. ANIMAL DRUGS. (NOT ELSEWHERE MENTIONED.) 1 3 1 3- Cantharis. Cantharides. Spanish Flies. The entire insect Cantharis vesicatoria {Coleoptera), Spain, Southern Russia, and other localities in southern Europe. About an inch long, %. inch broad; hard shell, shining copper green; odor 'peculiar, nauseous; taste nauseous, burning. The powder is grayish-brown, with green, shining particles. Applied to the skin, it vesicates. Contains the vesicant principle, cantharidin. Uses. — Stimulant, diuretic ; externally rubefacient, vesicant Dose of the Tincture, 5 to 15 minims. The preparations for external use are two Cerates, Collodion, Liniment, and Pitch Plaster with Cantharides. 1314. Fel Bovis. Ox-Gall. The fresh gall of beef cattle. Bos Taurus {Mammalia). Brownish green or dark green, of a oeculiar nauseous odor and an intensely bitter taste. 392 ABOUT DRUGS. In a purified state, evaporated down to an extract-like soft solid, it is still sometimes used as a purgative. Dose, 5 to 3 grains. 1315. Moschus. Musk. The dried secretion from the preputial follicles of Moschus Moschiferus (Mammalia) . Dark reddish-brown masses, or a crummy granular coarse powder, of a peculiar and very strong, penetrating, persistent odor, and bitterish taste. Contains resinous matter, etc Uses. — Stimulant, antispasmodic. Also used in perfumery. Dose of musk, 5 to 10 grains ; Tincture, 15 to So minims. 1316. Pepsinum. Pepsin. Pepsin is the digestive principle of the gastric juice, obtained from the mucous membrane of the stomach of the hog. The Saccharated Pepsin of the Pharmacopoeia is pepsin mixed with powdered milk sugar. It is white, and of slight, but not disagreeable odor and taste. Pepsin digests albumin, and the Pharmacopoeia requires that 1 part of Saccharated Pepsin shall digest at least 50 times its weight of hard white of egg within six hours, at 39 3 C. (i02°F.), when mixed with 500 parts of water acidulated with 7.5 parts of hydrochloric acid. Used in dyspepsia and apepsia. CHAPTER LXXIV. THERAPEUTIC CLASSIFICATION OF MEDICINES. 1317. Medicines are classified according to their therapeutic effects and mode of use. Thus they may first be divided into two great groups: 1, Sys- temic Medicines, which act on the whole body through their effect upon its organs and their functions; and 2, Topical Medicines, having local or limited effects. 1318. The systemic medicines may be divided into three classes: 1, Those acting upon the digestion, nutrition and the ABOUT DRUGS. 393 temperature of the body; 2, Those acting upon the several organs, as upon the nervous system, the circulatory organs, sexual organs and the alimentary canal; and 3, Those affecting the secretions. 1319. Systemic Medicines of the first class are: digestants, tonics, alteratives and antipyretics. Those of the second class are: A, hypnotics, mydriatics, ano- dynes, anaesthetics, antispasmodics, motor-excitants and motor- depressants; B, stimulants and sedatives influencing the circula- tion; C, aphrodisiacs, anaphrodisiacs, oxytocics, uterine seda- tives, and emmenagogues; D, emetics, gastric sedatives, carmina- tives, cathartics and anthelmintics. Systemic Medicines of the third class are: Diuretics, dia- phoretics, expectorants, astringents and antacids. 1320. Topical Medicines are divided into: antiseptics, irri- tants, demulcents, emollients and protectives. 1321. Digestants are medicines which aid digestion. Ex. Pepsin, pancreatin, papain, malt extract. 1322. Tonics are remedies which restore strength and energy to the body or its parts, or increase its vigor. The tonics are divided into vegetable tonics, or bitters, and mineral tonics. Bitter Tonics are numerous. Among them are gentian quassia, calumba, serpentaria, anthemis, bitter orange peel, absinthium, cinchona, salix, Hydrastis, etc. Mineral Tonics include the preparations of iron and phos- phorus, and the mineral acids. 1323. Alteratives do not act upon particular organs, but establish conditions favorable to the re-establishment of the healthy functions of the system. Among the most commonly employed alteratives are the preparations of mercury and gold, iodi?ie and iodides; arsenic j phosphates and hypophosphites; cod-liver oil; sarsaparilla, guaiac, stillingia and colchicum. 394 ABOUT DRUGS. 1324. Antipyretics reduce the temperature of the body when abnormally high, as in fevers. Ex. — Antipyrin, acetanilid, quinine, salicin, salicylates, salol, acet- phenetidin, resorcin, hydroquinone, chinoline, thalline and kairine. 1325. Hypnotics are remedies inducing sleep. They may be narcotics, which stupefy, or anodynes, which lessen excitement and relieve pain. The principal hypnotics are opium, morphine and codeine, hyoscy- amus, cannabis indica, bromides, chloral, paraldehyd, hypnone, ttrethan. 1326. Mydriatic Anodynes are used to relieve pain (as analgesics and antispasmodics); they dilate the pupil, and in large dose produce restless delirium instead of sleep. Belladonna, hyoscyamus, stramonium, erythroxylon and antipyrin are mydriatic anodynes . 1327. Anaesthetics are substances which, when f heir vapor is inhaled, produce insensibility to pain or to touch, and uncon- sciousness. The principal anaesthetics are ether, chloroform, nitroge?i mo?i- oxide, methylene bichloride and ethyl bromide. 1328. Antispasmodics are medicines which relieve or pre- vent spasmodic pain or the spasmodic action of the muscles. Among them are camphor, valerian, asafetida, musk, cypripedium, ether. 1329. Motor-Excitants are medicines which excite muscu- lar action by their stimulant effect upon the reflex centers of the spinal cord. The most important are nux vomica, strychnine and ignatia. 1330. Motor-Depressants are medicines producing effects the opposite of those of the motor-excitants (1329). They depress the functions of the spinal cord and lessen muscular activity. Hydrocyanc acid, chloral, bromides, physostigma, gelsemium, con- turn, lobelia and tobacco are motor-depressants. ABOUT DRUGS. 395 1331. Cardiac and Arterial Stimulants are medicines which increase the action of the heart and the force of the circu- lation of blood. Among the stimulants of the organs of circulation are: Alcohol, ether, ammonia, atropine, digitalis, strophanthus, strychnine y caffeine. 1332 . Cardiac and Arterial Sedativesare medicines which diminish the force and frequency of the heart contractions, and depress circulation. They are the opposite of the cardiac and arterial stimulants (1331). Aconite, veratrum viride, gelsemium, veratrine, and antimony prep- arations are sedatives of this kind. *333- Aphrodisiacs are remedies which excite the func- tions of the genital organs when morbidly depressed. Anaphrodisiacs are the opposite of aphrodisiacs, depressing the sexual functions when excited. 1334' Oxytocics are medicines which increase the contrac- tile power of the uterus. Ergot and cotton root bark are oxytocics. Uterine Sedatives are medicines which diminish or depress uterine contractions. Emmenagogues increase or re-establish the menstrual flow when suppressed from causes other than pregnancy or age. 1335. Emetics are medicines which induce vomiting. The most important emetics are ipecac, apomo?-phine and mus- tard, copious draughts of warm water, tartar e?netic, zinc sulphate, copper sulphate, alum and subsulphate of 7nercury. 1336- Carminatives are medicines which aid the expulsion of gases from the stomach and intestines. Drugs containing volatile oils, and the volatile oils them- selves, are used for this purpose, as anise, caraway, fennel, asafet- ida, oil of turpentine, eucalyptus, etc. 1337. Cathartics are medicines which cause the evacua- tion of the bowels, either by increasing the peristaltic motion of the intestines, or by augmenting the intestinal secretions. 39^ AEOUT DRUGS. Powerful cathartics are called drastic purgatives, and irritant cathartics producing watery stools by causing a copious increase of the secretions are called hydragogue cathartics, while medicines which relieve the bowels of their contents without irritation or purgation are called laxatives. Saline cathartics produce liquid stools not only by increasing peristalsis, but also by causing exosmosis of water from the blood vessels. Among the laxatives are castor oil, tamarinds, manna, frangula, rhamnus, purshiana and sulphur. Among the simple purgatives are rhubarb, aloes, senna, calomel and blue mass. The saline catliartics include the magnesium salts and rochelle salt. The drastic purgatives include jalap, scammony, gamboge, elaterin and elaterium, croton oil, podophyllum, etc. 1338. Anthelmintics are medecines employed to kill or expel intestinal worms. Those that kill the worms are called vermicides; medicines which expel the worms are caled vermifuges. Among the anthelmintics are aspidium, brayera, chenopodium, granatum, kamala, pepo, santonica and santonin, spigelia, and oil of turpentine. ' I 339« Diuretics are medicines which increase the flow of urine. They may be grouped into alkaline, hydragogue and alterative diuretics. Acetate, nitrate and bicarbonate of potassium, lithium citrate and ■chloride, and sodium acetate are alkaline diuretics. Squill, digitalis, caffeine, scoparius, and spirit of nitrous ether are hydrogogue diuretics. Buchu, pareira, uva ursi, chimaphila, juniqer, oil of turpentine, oil of santal, copaiba, cubeb, and matico are alterative diuretics. 1340. Diaphoretics are medicines which increase or cause perspiration. They are grouped into nauseating, sedative, saline and special diaphoretics. When they are so powerful as to bring on profuse sweating they are called sudorifics. ABOUT DRUGS. 397 Nauseant diaphoretics are represented by ipecac and Dover's powder. Sedative diaphoretics by antimony preparations, aconite and veratrum vivide, salicylic acid and other antipyretics. Among the saline diaphoretics are solution of ammonium acetate, spirit of nitrous ether, potassium citrate. Pilocarpus is a powerful sudorific or special diaphoretic. 1341. Expectorants are medicines employed to aid or modify the secretions of the air passages and promote the expul- sion of mucus and other fluids from the lungs and trachea. Among the sedative expectorants are ipecac (an emetic), tartar emetic (a sedative), pilocarpus (a diaphoretic) and lobelia (a motor- depressant). Grindelia is also a sedative expectorant. Among the stimulant expectorants (sometimes called blennor- rhetic) are senega, quillaia, squill, sanguinaria, ammoniac, benzoin, balsam of Peru, balsam of Tolu, eucalyptus, oil of turpentine, copaiba, tar, terebene, and ammonium chloride. 1342. Astringents are medicines usea to diminish secre- tion, which they do by causing the contraction of the tissues with which they come in contact. Among the vegetable astringents are tannic and gallic acids and drugs containing tannins, such as nutgall, oak bark, catechu, kino, krameria, hamatoxylon, geranium, and rhus glabra. Inorganic astringents include the soluble salts of aluminum, silver, lead, zinc and copper, and certain iron salts. 1343. Antacids are medicines which neutralize acids. The hydrates and carbonates of potassium, sodium, lithium and ammonium and the oxides, hydrates, and carbonates of calcium and magnesium are antacids. 1344. Antiseptics are substances which prevent or arrest the decomposition of organic matter. They do this by prevent- ing or arresting the development of the germs by which such decomposition is caused. Disinfectants also arrest putrefaction and the formation of unwholesome or offensive products of decomposition; but while antiseptics simply prevent or arrest the development of the germs which cause the fermentation, putrefaction or other 3q3 about drugs. organic changes, without destroying the products of decomposi- tion that may have been already formed, and without injury to healthy animal tissues, disinfectants always destroy the noxious products of decomposition, and frequently have an injurious or even destructive effect upon organic substances generally. Among the most commonly employed antiseptics are alcohol, boric acid, salicylic acid, carbolic acid, benzoic acid, thymol, volatile oils, as oil of eucalyptus and oil of cloves, quinine, populin, corrosive sub- limate, etc. Among the most powerful disinfectants are chlorine, bromine, iodine, potassium permanganate, sulphurous acid and the sulphites. 1345. Irritants are medicines applied locally to produce counter-irritation, inflammation, vesication, suppuration, and destruction of tissue. Rubefacients are irritants producing powerful but tempor- ary congestion of the surface to which they are applied. All vola- tile oils are counter-irritants and rubefacients, but among the most common rubefacients are mustard, capsicum, and ammonia liniment. Vesicants are remedies which raise blisters when applied to the skin, such as cantharis, crotonoil, etc. Escharotics destroy the tissues with which they come in con- tact, and therefore cause sloughing and eschar. Among the esoharotics are the caustic alkalies, strong acids, bromine, zinc chlo- ride, solution of nitrate of mercury, etc. 1346. Demulcents are remedies administered internally for their soothing effect upon irritated or inflamed surfaces. Among them are water, gums, and mucilages, decoctions of starch, barley, rice, althaia, etc. 1347 Emollients are bland fatty substances, fomentations or poultices, glycerin, etc., applied externally to soften the skin. ABOUT DRUGS. 399 CHAPTER LXXV. 1348. Dose Table of medicines in frequent use, includ- ing new remedies, in metric as well as apothecaries' weights and measures. Remedies. Absinthium , extr fluid extr Abstracts, see each drug. Acetanilid ' Acetphenetidin ... Achillea, fl. ext extr Acid, acet. dil arsenos liquor benzoic boric carbolic gallic " in albuminuria. hydriod., sir hydrobrom. dil. ... . hydrochlor. dil hydrocyan. dil lactic nitric, dil nitrohydrochlor dil... phosph. dil , salicyl sulph. arom «' dil tannic , Aconiti fol " extr " fl. extr Single Adult Dose. Metric Weights and Measure^ 100 to 600 mGm 1 to 2 C. c. 300 300 200 500 300 250 to 500 mGm 4 to 200 to 500 mGm 3 to 1 to 4 C. c. 15 to 2C0 to 600 mGm 3 to 4 to 6 C. c. 1 to 1 to 5 mGm i\ to 0.10 toO on C. c. 2 to mGm to 1 Gm 5 to' mGm to 1 Gm 5 to 60 to 200 mGm 1 to mGm to 1 Gm 3 to mGm to 4 Gm 8 to 1 to 5 C c. 15 to 1 to 3 C. c. 15 to 0.50 to 2 C. c. 8 to 0.10 to 0.30 C. c. 2 to 1 to 4 Gm 15 to 0.50 to 2 C. c. 8 to 200 to 600 mGm 3 to 0.30 to 1.30 C. c. 5 to 0.50 to 4 C. c. 8 to mGm to 1 Gm 5 to 0.20 to 1 C. c. 3 to 0.30 to 2 C. c 5 to 100 to 600 mGm 1 to 50 to 250 mGm 1 to 15 to 30 mGm ito 0.05 to 0.20 C. c. 1 to Oid Apothecaries' \ Weights and Measures. 2 to 10 gr . 15 to 30 min. 8 gr. 8 gr. 60 min. 10 gr. \\ fl. dr. tV gr. « min. 15 gr. 15 gr. 3 gr. 15 gr. 60 gr. 80 min. 50 min. 30 min. 5 min. 60 gr. 31) min. 10 gr. 20 min. 60 min. 15 gr. 15 min 30 min. 10 gr. 4gr. igr. 3 min. Note. — The dose for a child is found by dividing the age in years at next birthday by 24 and multiplying the adult dose by the quotient. The dose to # be administered hypodermatically \s one-half of the dose given by mouth. The dose to be administered by rectum is 25 per cent, larger than that administered by mouth. 400 ABOUT DRUGS. Remedies. Aconiti fol. tinct rad " abstr " extr " fl. extr " tinct " " Fleming. . Aconitina (pure, cryst.) Adonidin Aether spir •' comp. Agaricin Allii syr Aloe, purgtive decoct, comp extr. pil tinct et asaf. pil , " ferri pil . , " mast, pil , " myrrh, pil " " tinct. . . . Aloin Alstonia, fl. extr , Alumen ustum Ammoniacum mist Ammoniae spir. " arom Ammonii benzoas bromid carb chlorid iodid phosph picras , sulph , valer Amyl nitris Amylen. hydrat Amylum iodat Angustura, fl. extr Anthemis, extr. ...... , fl. extr , Antifebrin Single Adult Dose. Metric Weights and Measures. Old Apothecaries' 1 Weights and Measures. 0.50 to 1 C. c. 8 to 15 min. 30 to 100 mGm . 1 to 1^ gr. 15 to 50 mGm i to 1 gr. 5 to i5 mGm TS to i S r - 0.05 to 0.15 C. c. 1 to 2 min. 0.10 to 0.25 C. c. 2 to 4 min. 0.05 to 0.20 C. c. 1 to 3 min. 0.15 to 0.30 mGm ■gfo-to-zfa; S r - 8 to 30 mGm i to i gr. 2 to 4 C.'c. % to 1 fl. dr. 2 to 5 C. c. 30 to 80 min. 2 to 4 C. c. | to i fl. dr. 10 to 100 mGm 5 to 15 C. c. 200 mGm to 1 Gm 15 to 60 C. c. 30 to 200 mGm 3 to 6 pills 1 to 5 C. c. 2 to 5 pills 2 to 4 pills 1 to 2 pills 3 to G pills 5 to 10 C c. 8 to 60 mGm 5 to 15 C. c. 300 mGm to 1 Gm 100 to 500 mGm 0.500 to 2 Gm 15 to 30 C. c. 1 to 2 C. c. 3 to 10 C. c. 0.300 to 1.300 Gm 0.300 to 2 Gm 200 to 500 mGm 0.300 to 2.200 Gm 50 to 500 mGm 0.500 to 1.500 Gm 15 to 30 mGm 200 mGm to 1 Gm 100 to 500 mGm 2 to 5 drops 1 to 4 Gm 0.20 to 2 Gm 1 to 2.50 C. c. 100 to 650 mGm 2 to 4 C. c. 250 to 500 mGm i to 1-*- gr. 1 to 4 fl. dr. 3 to 15 gr. | to 2 fl. ozs. & to 3 gr. 3 to 6 pills 15 to 80 min. 2 to 5 pills 2 to 4 pills 1 to 2 pills 3 to 6 pills 1 to 2 fl dr. i to 1 gr. 1 to 4 fl. dr. 5 to 15 gr. 2 to 8 gr. 8 to 30 gr. | to 1 fl oz. 15 to 30 min. i to 21 fl. dr. 5 to 20 gr. 5 to 30 gr. 3 to 8 gr. 5 to 40 gr. 1 to 8 gr. 8 to 24 gr. i to i gr. 3 to 15 gr. ' 2 to 8 gr. 2 to 5 drops 15 to 60 gr. 3 to 30 gr. 15 to 40 min. 2 to 10 gr. 30 to 60 min. 4 to 8 gr. ABOUT DRUGS. 401 Single Adult Dose. Remedies. Metric Weights and Measures. . . . \ antipyretic. . . Antipynn j ana £ ?sic Ant. et pot. tart ,diaphor. . . emetic . . . Antim. oxid Antim. oxysulph pil. comp sulphid sulphurat { expect vinum < r . I emet Apiol Apocyn, fl. extr Apomorphine Aqua amygd. amar. . . .... camph chlori creasoti laurocerasi Areca, fl. extr Argenti iodid nitras oxid Arnicae flor. . fl. extr " tinct rad., extr " fl. extr " tinct Arsenic — arsenous acid iodid sod. arsenate liqu. acid, arsen " arsen. et hydr. iod " pot. arsenitis. . . " sol. arsenatis. . . . Asafoetida mist Pil tinct Asarum, fl. extr Asclepias, fl. extr Aspidium fl. extr oleoresin Aspidosperma. abstr extr 500 mGm 4 30 50 30 1 30 30 0.06 2 200 0.20 2 5 10 5 5 0.50 5 60 15 30 0.25 1 60 0.30 2 1 1 1 0.10 10 0.10 0.10 300 mGm 15 2 2 1 1 4 4 1 1 0.500 200 o 2 Gm o 1 Gm o 10 mGm o 120 mGm o 250 mGm o 100 mGm o 3 pills o 100 mGm o 100 mGm o 0.50 C. c. o 5 C. c. o 300 mGm o2C. c. o 4 mGm o 15 C. c. o 60 C. c. o 15 C. c. o 15 C. c. o2 C. c. o 15 C. c. o 125 mGm o 30 mGm o 125 mGm o 1.50 C. c. o 3 C. c. o 200 mGm ol.50C. c. o 6 C. c. o 3 mGm o 3 mGm o 3 mGm oO.SO C. c. o 0.50 C. c. 0.50 C. c. 0.50 C. c. 1 Gm 30 C. c. 6 pills 4C. c. o2C. c. o2C. c. o 15 Gm o 15 C. c. o 4 Gm o 3 Gm o 1 Gm o 500 mGm Old Apothecaries'* Weights and Measures. 13 30 gr. 15 gr. igr. 2gr. 4gr. 2gr. 3 pills. 2gr. 2gr. 8 min. 80 min, 5 gr. 30 min. tV gr. 4 fl. dr. 2 fl. ozs. 4fl. dr. 4 fl. dr. 30 min. 4 fl. dr. 2gr. igr. 2gr. 20 min. 45 min. 3gr. 20 min. 90 min. ■h gr. in g r - inr g r - 8 min. 8 min. 8 min. 8 min. 15 gr. 1 fl. oz. 6 pills 60 min. 30 min. 30 min. 4 dr. 4 fl. dr. 60 gr. 40 gr. 15 gr. 8gr. 4-02 ABOUT DRUGS. Remedies. Aspidosperma, fl. extr tinct Aspidospermine Atropine, and salts . . . Aurant, amar., fl. extr tinct Auri et Sodii chlorid. . Azedarach, fl. extr.. . . Bebeerine, and salts . Bellad. fol " abstr " extr " fl. extr " tinct rad " abstr *' extr " fl. extr " tinct Berberine, and salts. . Berberis, fl. extr Betol Bismuthi citras. et ammon. citr. . . oxid salicyl subcarb . , subnitr tannas valer Boldus, fl. extr Brayera fl. extr inf Bromum , Brucine, and salts Bryonia, fl. extr tinct Buchu, fl. extr. ...... Caffeine, and salts Calamus, fl. extr Calcii brom carb hypophosph iodid lactophosph. syr. . phosphas sulphid Calcis syrupus Single Adult Dose. Metric Weights and Measures. Old Apothecaries" Weights and Measures. 1 to 3 C. c. 15 to 45 min. 5 to 15 C. c. 1 to4fl. dr. 60 to 300 mGm 1 to 3 gr. 0.50 to 2 mGm Tib- to h g r - 1 to IOC. c. 15 to 160 min. 5 to 30 C. c. 1 to 4 fl. dr. 2 to 4 mGm A to tV g r - 1 to 5 C. c. 15 to 80 min. 200 to 600 mGm 3 to 10 gr. 200 to 500 mGm 3 to 8 gr. 60 to 200 mGm 1 to 3 gr. 6 to 20 mGm T* to \ gr. 0.15 to 0.30 C. c. 1 to 4 min. 0.40 to 1 C. c. 8 to 15 min. 60 to 200 mGm 1 to 3 gr. 30 to 100 mGm i to H Sr. 5 to 10 mGm ■h to £ gr. 0.10 to 0.20 C. c. 1 to 3 min. 0.20 to 0.60 C. c. 3 to 10 min. 0.200 to 1 Gm 3 to 15 gr. 1 to 2 C. c. 15 to 30 min. 1 to 2 Gm 15 to 30 gr. 0.200 to 1 Gm 3 to 15 gr. 0.100 to 1 Gm 1 to 15 gr. 0.200 to 1 Gm 3 to 15 gr. 0.200 to 1 Gm 3 to 15 gr. 0.200 to 2 Gm 3 to 30 gr. 0.200 to 2 Gm 3 to 3D gr. 0.200 to 2 Gm 3 to 30 gr. 0.100 to 1 Gm 1 to 15 gr. 0.20 to 1 C. c. 3 to 15 min. 8 to 15 Gm 2 to 4 dr. 8 to 15 C. c. 2 to 1 fl. dr. 60 to 250 C. c. 2 to 8 fl. ozs. 30 to 100 mGm \ to \\ gr. 1 to 4 mGm ■fa to & gr. 1 to 2 C. c. 15 to 30 min. 2 to 5 C. c. 30 to 80 min. 2 to 10 C. c. 30 to 160 min. 60 to 300 mGm 1 to 4 gr. 1 to 4 C. c. 15 to 60 min. 0.300 to 2 Gm 5 to 30 gr. 1 to 4 Gm 15 to 60 gr. 0.200 to 1 Gm 3 to 15 gr. 60 to 200 mGm 1 to 3 gr. 5 to IOC. c. 1 to 2 fl. dr. 1 to 2 Gm 15 to 30 gr. 15 to 60 mGm i to 1 gr. 1 to 2 C. c. 15 to 30 min. ABOUT DRUGS. 4°3 Remedies. Calend. fl. extr ct Calomel Calumba, extr fl. extr tinct Calx. Sulphurata Cambogia .. Camphora aqua spir monobrom Canella, fl. extr Cannabin, tannat Cannabis indica " abstr.. " extr... " fl. extr " tinct... Cantharis fl. extr tinct Capsicum fl. extr oleores tinct Cascarilla, fl. extr Castanea, fl. extr Castoreum tinct Catechu tinct Caulophyll, fl. extr Chimaphila. fl. extr Chinoidinum Chinolina, and salts Chirata, fl. extr.. tinct Chloral croton Chloralamid Chloroform mist spir Chrysarobin Cimicif., extr. fl extr. tinct Single Adult Dose. Metric Weights and Measures. Old Apothecaries'* Weights and Measurts. 1 to 4 C. c. 15 to 60 min. 4 to 15 C. c. 1 to 4 fl. dr. 10 to 500 mGm i to 8 gr. 200 to 600 mGm 3 to 10 gr. 1 to 4 C. c. 15 to 60 min. 5 to 15 C. c. 1 to 4 fl. dr. 15 to 60 mGm i to 1 gr. 60 to 250 mGm 1 to 4 gr. 100 to 600 mGm H to 10 gr. 15 to 60 C. c. \ to 2 fl. ozs. 0.50 to 2 C. c. 8 to 30 min. 100 to 300 mGm 2 to 5 gr. 1 to 4 C. c. 15 to 60 min. 1 to 15 mGm fa to i gr. 200 to 400 mGm 3 to 6 gr. 100 to 200 mGm H to 3 gr. 10 to 60 mGm \ to 1 gr. 0.20 to 0.40 C. c. 3 to 6 min. 1 to 2 C. c. 15 to" 30 min. 30 to 60 mGm i to 1 gr. 0.03 to 0.06 C. c. \ to 1 min. 0.50 to 1 C. c. 8 to 15 min. 60 to 200 mGm 1 to 3 gr. 0.06 to 0.20 C. c. 1 to 3 min. 10 to 30 mGm i to \ gr. 0.50 to 1 C. c. 8 to 15 min. 3 to IOC. c. 40 to 150 min. 3 to lOC.c. 40 to 150 min. 0.400 to 1 Gm 6 to 15 gr. 1 to4C. c. 15 to 60 min. 1 to 2 Gm 15 to 30 gr. 2 to 8 C. c. \ to 2 fl. dr. 1 to 2 C. c. 15 to 30 min. 2to4C. c. 30to60C.c. 0.200 to 2 Gm 3 to 30 gr. 0.200 to 1 Gm 3 to 15 gr. 1 to 2 C. c. 15 to 30 C. c. 2 to 8 C. c. 30 to 120 C. c. 0.200 to 1 Gm 3 to 15 gr. 50 to 600 mGm 1 to 10 gr. 1 to 2 Gm 15 to 30 gr. 0.05 to 0.30 C. c. 1 to 5 min. 5 to 15 C. c. 1 to 4 fl. dr. 1 to 4 C. c. 15 to 60 min. 0.200 to 1 Gm 3 to 15 gr. 0.100 to 0.500 Gm 2 to S gr. 0.50 to 2 C. c. 8 to 30 min. 2to4C. c. 30 to 60 min. 4 o4 ABOUT DRUGS. Remedies. Cinchona abstr . . . ... extr inf fl. extr tinct " comp Cinchonidina, and salts Cinchonina, and salts.,. Cinnamomum fl. extr tinct Cocaina and salts Cocculus, fl. extr Codeina Colch. rad " extr " fl. extr " tinct " vin " sem. fl. extr. '• tinct " vin Colocynthis extr extr. comp fl. extr Comptonia, fl. extr Condurango, fl. extr.... Conhydrine, and salts.. Conii fruct " abstr " extr " fl. extr " tinct herb " abstr " extr " fl. extr " tinct.. Coniina, and salts Convallaria, fl. extr Copaiba massa oleum. c resina Cornus. fl. extr Corydalis, fl. extr Single Adult Dose. Metric Weights and Measures. 1 to 4 Gm 0.500 to 2 Gm 0.200 to 1 Gm 15 to 60 C. c. 2 to 4 C. c. 4 to 12 C. c. 4 to 12 C. c. 0.060 to 2 Gm 0.060 to 2 Gm 0.400 to 2 Gm 0.50 to 1 C. c. 1 to 5 C. c. 10 to 60 mGm 0.05 to 0.50 C. c. 30 to 100 mGm 100 to 500 mGm 30 to 100 mGm 0.10 to 0.50 C.c. 0.50 to 2C. c. 0.50 to 2 C. c. 0.20 to 0.50 C. c. 0.50 to 2 C. c. 0.50 to 2 C. c. 0.500 to 1 Gm 100 to 300 mGm 100 to 300 mGm 0.50 to 2 C. c. 2 to 8 C. c. 0.50 to 2 C. c. 1 to 3 mGm 100 to 400 mGm 60 to *00 mGm 20 to 60 mGm 0.06 to 0.30 C. c. 0.30 to 2 C. c. 0.300 to 1 Gm 100 to 500 mGm 50 to 150 mGm 0.20 to 1 C. c. 0.50 to 4 C. c. 1 to 2 mGm 1 to 2 C. c. 1 to4C. c. 1 to 4 Gm 0.50 to 1 C. c. 0.200 to 1 Gm 2 to 4 C. c. l'to 2 C. c. Old Apothecaries' Weights and Measures. 15 to 60 gr. 8 to 30 gr. 3 to 15 gr. \ to 2 fl. ozs. 30 to 60 min. 1 to 3 fl. dr. 1 to 3 fl. dr. 1 to 30 gr. 1 to 30 gi . 6 to 30 gr. 8 to 15 min. 15 to 80 min. i to 1 gr. 1 to 8 min. | to 2 gr. 2 to 8 gr. 1 to 2 gr. 2 to 8 min. 8 to i min. 8 to SO min. 3 to 8 min. 8 to 80 min. 8 to 30 min. 8 to 1 5 gr. 2 to h gr. 2 to 5 gr. 8 to 30 min. | to 2 fl. dr. 8 to 30 min. it to ¥o gr. 2 to (J gr. 1 to 3 gr. i to 1 gr. 1 to 5 min. 5 to 30 min. 4 to 15 gr. 2 to 8 gr. f to 2 gr. 3 to 15 min. 8 to 60 min. ■h to -h gr. 15 to 30 min. 15 to 60 min. 15 to 60 gr. 8 to 15 min. 3 to 15 gr. 30 to 60 min. 15 to 30 min. ABOUT DRUGS. 405 Remedies. Coto abstr extr . . . fl.extr tinct Cotoinum Creasotum aqua Creta mist. i pulv. comp Crocus tinct Croton-chloral Cubeba fl. extr oleum oleores tinct Cupri acet sulph Cuprum ammon Curare Curarina Cypriped, fl. extr Damiana, fl. extr Daturina Delphin. , fl. extr Digitalinum Digitalis abstr extr fl. extr infus tinct Dioscorea, fl. extr Dracont. , fl. extr Drosera, fl. extr Duboisina, and salts Dulcamara, extr fl extr Elaterin (U. S. P., 1880).. . tritur Elaterium (U. S. P., 1870)... Emetina, and salts, diaphor. " " emet . . . Ergota extr Single Adult Dose. \Tetric Weights and Measures 0.200 100 50 0.20 1 10 0.05 4 1 30 0.500 0.300 4 0.200 1 1 50 0.50 4 30 30 10 2 1 1 2 0.50 0.06 1 50 30 10 0.20 10 0.30 1 2 0.50 0.50 0.300 4 1 10 4 0.50 8 1 0.200 o 1 Gm o 500 mGm o 200 mGm o 1 C. c. o 4 C. c. o 30 mGm o 0.20C. c. o 15 C. c. o 5 Gm o 60 C. c. o 2 Gm o 2 Gm o 8 C. c. o 1 Gm o 4 Gm o2 C.c o 1 C. c. o 2 C. c. 08C. c. o 200 mGm o 500 mGm o 60 mGm o 10 mGm o 3 mGm o4C. c olOC. c. o 1 mGm o0.20C. c. o 2 mGm o 200 mGm o 100 mGm o 30 mGm o2C. c. o 20 C. c. o 4 C. c. o2C. c. o4C. c. o 1 C. c. b 1 mGm o 1 Gm 08 C. c. o 4 mGm o 40 mGm o 30 mGm o 2 mGm o 15 mGm o 4 Gm o 1 Gm Otd Apothecaries' 1 Weights and Measures. 33 1 6T 15 30 lis 1 5 1 1 6 tV T"2~8 o 15 gr. o 8 gr. o 3_gr. o 15 min. o 60 min. j gr. o 3 min. o 4 fl. dr. o 80 gr. o 1 fl. dr. o 30 gr. o 30 gr. o 2 fl. dr. o 15 gr. o 60 gr. o 30 min. o 15 min. o-30 min. o 2 fl. dr. o3gr. o 8 gr. o 1 gr. oigr. °-fa g r - o 60 min. o 150 min. o ei g r - o 8 min. o sV gr. o 3 gr. o 2 gr. o£gr- o 30 min. o 5 fl. dr. o 60 min. o 30 min. o 60 min. o 15 min. o A g r - o 15 gr. o 2 fl. dr. o tV g r - ofgr. °igr- o 3V gr. o Jrgr. o 60 gr. o 15 gr. 4c6 AEOUT DRUGS. Single Adult Dose. Remedies. Metric \Veighis and Measures. Old Apothecaries' 1 Weights and Measures. Ergota fl. extr tinct vin Ergotinum Erigeron, fl. extr oleum Eriodictyon, fl. extr Ervthroxylon, fl extr Eserina, and salts Eucalyptus, fl. extr oleum Euonymus, extr fl'. extr Exalgin Extracts, see each drug. Fel bovis purif Ferri acet. tinct arsen benzoas brom " syr carb. sacch , " massa chlorid chlorid. liqu , tinct citr " liqu " vin et ammon. citr , et " sulph.... et " tartr et cinch, citr et pot. tart , et quin. citr , et strych. citr extr. pom ferrocyanid , h}-pophosphis syr.... iodid " Pil " sacch " syr lactas liquor dialys mist, comp nitr. liqu oxalas 1 to 4 to 4 to 0.200 to 4 to 0.30 to 1 to 2 to 1 to 1 to 0.60 to 200 to 1 to 250 to 8 C. c. 15 C. c. 15 C. c. 1 Gm u. c. C. c. C. c. C. c. mGm C. c. C. c. 500 mGm 4C. c. 500 mGm 200 1 6 60 60 0.50 250 0.250 50 0.10 1 300 0.60 300 300 0.500 100 0.500 100 60 250 200 250 30 1 120 1 100 0.50 200 to 400 mGm to 2 C. c. to 60 mGm to 300 mGm to 300 mGm to 3 C. c. to 1 Gm to 1 Gm to 200 mGm to 0.60 C. c. to 2 C. c. to 600 mGm to 1 C. c. 4C. c. to 600 mGm to 600 mGm to 2 Gm to 500 mGm to 2 Gm to 500 mGm to 200 mGm to 500 mGm to 400 mGm to 500 mGm 4C. c. to 150 mGm to 5 pills to 500 mGm to 4 C. c. to 500 mGm to 2 C. c. to 30 C. c. 0.50 C. c. to 300 mGm 15 min. 1 1 3 1 . 5 15 30 15 10 3 15 4 8 15 i 10 1 1 8 4 4 1 2 15 5 10 5 5 8 2 8 2 1 4 2 fl. dr. o 4 fl. dr. o4fl. dr. o 15 gr. o 2 fl. dr. o 15 min. o 30 min. o 60 min. o ^o gr. - o 60 min. o 30 min. o 8gr. o 60 min. o 8 gr. 3 to 6 gr. 30 min. Igr- 5 gr. 5 gr. 45 min. 15 gr. 15 gr. 3 gr. 10 min. 30 min. 10 gr. 15 min. 1 fl. dr. 10 gr. 10 gr. 30 gr. 8gr. 30 gr. 8gr. 3gr. 8gr. 6 gr. 8gr. 1 fl. dr. 2gr. 5 pills 8gr. 60 min. 8gr. 30 min. 8 fl. dr. 8 min. 5 gr. Remedies. -,z:v: z?.v :- ; . Ferri oxid. hydra: magnet '* sacch " " syi pil. comp phosphas, 1870 phosphas, 1880 pom. tinct pyrophosphas subcarb sulph :xsicc valer vin. amar " dulc Ferrum dialysat reductum Fr-mcma. :■::: fl. ex:r Fluid extrs. , see each drug. . Fuchsin Galbanum pil. comp Galla tinct Gelsemium abstr extr fl. extr tinct Gentiana extr - t:::: inf. comp tinct " comp Geranium, fl. extr Glonoin. 1 per cent. sol. .. Glycyrrhiza. pulv. comp. . . s s pium, fl. ex:r Granatum decoct \: f. -.-- Grindelia. fl. extr Guaiari Hgn fl. ex:r resina •' tinct " " a mm or. ! : X I : lto 20v :-- 2i0 :: 1 to 2.>. :: ?■■:>.<■-. I'!"' :: "■0 :: SOU : r tc BO tc 2 ; i 2 to 60 to 0.5:': :: a 2 to 10 :: 60 to 2'. : ~ I a 15 to 2 tc 2tc : i 2 :: 2 tt 2 I 60 to o.o •: -.- a i 2 to 2 to 0.500 to 2 to O -- 1 r ::. 4C. c. ~ ~: .5 £'": m.Gm • ■: : mGm 2 C. c. : : : m :-~ '■':■'.■ m --:. '-' m G " : ~ :,r.-. 2 : ~j- 4 C. c. 4C. c. 2 C. c. i : mGm 6C. c. 900 mGm 1 Gm 3 cms 1 Gm 4 C :. 3 2: : - 60 mGm KS C. c. a C. : 1 Gm 4C. c. : c 5 C c. - C. :. 4C. c. C. c. 4 Gm 4C. c. 5 Gm : X C. c. 1 Gm 4C. c. ~ C. c. 5 Gm 4C. c. 1 Gm 4C. c. 4C. : to 5 to 5 to lto 3 to 3 to 3:o 4 to 2 :: 1 to 1 to 5 :: lto 3 to - ?r :: - 1 i ir. 4 pills 5gr. gr . mm. : ir 8gr. 4gr. 2 gi 3 ST. 1 ~. ir. 1 fl. dr. c : -ir.. 5gr. 8gr. 2 f ir. 1 to £ gi 6 to 16 gr. . - : - = S :o 16 gr. :-:: :: •; . mm. 2 : c S ; r 1 to 4 gr. i to 1 gr. 2 to 8 min. M : c : ; 3 to 15 gr. ?■'_> :: ■?. mm. | to 1 fl. oz. i to 2 fl. dr. £ to 2 fl. dr. 15 to 60 min. ^ min.— 30 to 60 gr. \ o : : ■:' ' mm. 30 :: r ~. 2 to 4 fl. ozs. 8 to 15 gr. 30 to 60 min. SO :: Ov mm 10 to 80 gi m :: •: ' mm. 8 to 16 gr. 30 to 60 rain. : : : mm 40 8 ABOUT DRUGS. Remedies. Metric. Weights and Measures, Guaiacol Guarana fl. extr Hsematoxylon, decoct extr fl. extr Hamamelis, fl. extr Helleb nig., extr fl. extr tinct Homatropina, hydrobrom Humulus, extr fl. extr tinct Hydrangea, fl. extr Hydrarg. chlorid. corros. " mite... cyanid iodid flav "*' rubr " vir massa oxid. flav . . . " nigr " rubr. Pil subsulph. flav c. creta salicylas ungu Hydrastis extr fl. extr tinct Hydroquinone Hyoscina, and salts Hyoscyamina, and salts.. Hyoscyamus abstr extr fl. extr tinct Hypnone Hypophosphitum syr. . . . Ichtyol Ignatia abstr extr Single Adult Dose. 0.06 C. c. 1 to 4 Gm 2 to 4C. c. 30 to 60 C. c. 250 to 600 mGm 2 to 4 C. c. 4 to 8 C. c. 50 to 200 mGm 0.20 to 1 C. c. 1 to 4 C. c. 0.30 to 1 mGm 60 to 300 mGm 2 to 4 C. c. 4 to 8C. c. 2 to 4C. c. 4 to 6 mGm 0.005 to 1 Gm 4 to 15 mGm 4 to 50 mGm 3 to 8 mGm 4 to 50 mGm 0.120 to 1 Gm 3 to 5 mGm 3 to 5 mGm 3 to 5 mGm 0.250 to 1 Gm 60 to 120 mGm 30 to 750 mGm 60 m Gm 0.250 to 1 Gm 0.500 to 2Gm 100 to 300 mGm 0.50 to 2C. c. 2 to 8C. c. 100 to 600 mGm 0.10 to 0.50 mGm 0.30 to 1 mGm 200 to 500 mGm 60 to 300 mGm 30 to 200 mGm 050 to 2 C. c. 2 to 8 C. c. 0.06 C c. 4C c. 025 to 1.30 C. c. 50 to 200 mGm 30 to 120 mGm 15 to 30 mGm Old Apothecaries'* Weights and Measures. 1 min. 15 to 60 gr. 30 to 60 min. 1 to 2 fl. ozs. 4 to 10 gr. 30 to 60 min. 1 to 2 fl. dr. 1 to 3 gr. 3 to 15 min. 15 to 60 min. irio to 100 to 300 mGm 2 to 5 gr. 0.300 to 2 Gm 5 to 30 gr. 2 to 4 C. c. 30 to 60 min. 200 to 500 mGm 3 to 8 gr. 2 to 8 C. c. 30 to 120 min. 0.500 to 2 Gm 8 to 30 gr. 0.300 to 1 Gm 5 to 15 gr. 2 to 8 C. c. ito 2 fl. dr. 4 to 30 C. c. 1 to 8 fl. dr. 1 to 5 pills 1 to 5 pills 1 to 3 pills 1 to 3 pills 1 to 4 Gm 15 to 60 gr. 4C. c. 1 fl. dr. 4C. c. 1 fl. dr. 4 to 15 C. c. 1 io 4 fl. dr. 4 to 15 C. c. 1 to 4 fl. dr. 4 to 15 C. c. 1 to 4 fl. dr. 4 to 15 C. c. 1 to 4fl. dr. 2 to 4 C. c. 30 to 60 min. 2 to 4 C. c. 30 to 60 min. 4 to 8 C. c. 1 to 2 fl. dr. 8 to 15 C. c. 2 to 4 fl. dr. 2 to 4 C. c. 30 to 60 min. ABOUT DRUGS. 415 Remedies. Sabina, fl. extr oleum Salicin Saloi Sanguinaria abstr acet fl. extr Sanguinarina, and salts. Santonica fl. extr Santonin album Sapo Sarsap. dec. comp fl. ext " comp syr. " Scammonium resina Scilla acet fl. extr syr " comp tinct Scoparius, fl. extr ...... Scutellaria, fl. extr Senega abstr fl. extr syr Senna conf fl. extr. inf. comp syr Serpentaria , fl. extr tinct Sodae liquor Sodii acet arsenas benzoas bicarb. bisulphis boras bromid Single Adult Dose. Metric Weights and Measures. 0.30 2 1 0.300 0.100 50 1 0.50 1 1 1 50 100 0.300 90 4 2 4 0.500 100 0.060 0.60 0.20 2 2 0.50 2 4 0.500 200 0.50 4 2 4 4 30 4 2 2 4 0.50 1 1 1 1 1 1 1 to 1.50 C. c. to 5 drops to 2 Gm to 4 Gm to 1 Gm to 400 mGm to 2 C c. to 1 C. c. to 3 mGm to 4 Gm to 2 C. c. to 250 mGm to 500 mGm to 1 Gm to 150 C. c. to 8 C. c. to 8 C. c. to 15 C. c. to 1 Gm to 300 mGm to 1 Gm to 2 C. c. to 1 C. c. to 4 C. c. to 4 C. c. to 2 C. c. to 4 C. c. to 8 C. c. to 1 Gm to 500 mGm to 1 C. c. to 8 C. c. to 8 Gm to 8 Gm to 15 C. c. to 60 C. c. to 15 C. c. to 4 Gm to 4 C. c. to 8 C. c. to 2 C. c to 4 Gm to 3 mGm to 2 Gm to 2 Gm to 2 Gm to 2 Gm to 4 Gm Old Apothecaries' 1 Weight and Measures. 5 to 20 min. 2 to 5 drops. 15 to 30 gr. 5 to 60 gr. 2 to 15 gr. 1 to 6 gr. 15 to 30 min. 8 to 15 min. is to h S v - 15 to (5U gr. 15 to 30 min. 1 to 4 gr. 2 to 8 gr. 5 to 15 gr. 3 to 5 fl. ozs. 1 to 2 fl. dr. I to 2 fl. dr. 1 to 4 fl. dr. 8 to 15 gr. 2 to 5 gr. 1 to 15 gr. 10 to 30 min. 3 to 15 min. 30 to 60 min. 30 to 60 min. 8 to 30 min. 15 to 60 min. 1 to 2 fl. dr. 8 to 15 gr. 3 to 8 gr. 8 to 15 min. 1 to 2 fl. dr. 30 to 120 gr. 1 to 2 dr. 1 to 4 fl. dr. 1 to 2 fl. ozs. 1 to 4 fl. dr. 30 to 60 gr. 30 to 60 min. 1 to 2 fl. dr. 8 to 30 min. 15 to 60 gr. eV to io S r - 15 to 30 gr. 15 to 30 gr. 15 to 30 gr. 15 to 30 gr. 15 to 60 gr. 416 ABOUT DRUGS. Remedies. Sodii carb " exsicc chloras hypophosphis. . . . hyposulphis iodid nitris phosph salicylas santoninas sulphas sulphis valeras Sparteina Spigelia fl. ext et senna, fl. extr. Spir. setheris " comp. . . " nitros. . ammonias arom. . . camphorae chloroformi lavand. comp. . menthas pip Stillinsda, fl. extr Single Adult Dose. Metric Weights and Measures. comp Stramon. syr. fol., extr fl. extr sem. abstr " extr fl. extr tinct Strophantin Strophantus, tinct. (10 fc). Strychnina, and salts Sulfonal Sulphur Sumbul, fl. extr tinct Svrup. acidi hydriod allii , calcii lactophosph calcis ferri brom " iod 1 to 2 Gm 0.500 to 1 Gm 0.500 to 1 Gm 0.500 to 1 Gm 0.500 to 1 Gm 1 to 2 Gm 100 to 200 mGm 0.500 to 4 Gm 0.300 to 2 Gm 100 to 500 mGm 8 to 30 Gm 1 to 4 Gm 100 to 500 mGm 15 to 100 mGm 2 to 4 Gm 2 to 4 C. c. 4 to 8 C. c. 2 to 4 C. c. 2 to 4 C. c. 2 to 8 C. c. 0.50 to 2 C. c. 1 to 4 C. c. 0.50 to 2 C. c. 1 to 4 C. c. 2 to 4 C. c. 2 to 4 C. c. 4to8C. c. 4 to 8 C. c. 4 to 15 C. c. 30 to 60 mGm 0.10 to 0.50 C. c. 20 to 60 mGm 10 to 40 mGm 0.05 to 0.30 C. c. 0.50 to 2 C. c. 0.40 tol mGm 0.03 to 0.50 C. 0.40 to 3 mGm 1 to 3 Gm 4 to 15 Gm 1 to 2 C. c. 2 to 8 C. c. 1 to 5 C. c. 4 to 15 C. c. 4 to 8 C. c. 1 to 2 C. c. 1 to4C. c. 1 to 4 C. c. c. Old Apothecaries'' Weights and Measures. 15 to 30 gr. 8 to 15 gr. 8 to 15 gr. 8 to 15 gr. 8 to 15 gr. 15 to 30 gr. 2 to 3 gr. 8 to 60 gr. 5 to 30 gr. 2 to 8 gr. 2 to 8 gr. 15 to 60 gr. 2 to 8 gr. i to 2 gr. 30 to 60 gr. 30 to 60 min. 1 to 2 fl. dr. 30 to 60 min. 30 to 60 min. 30 to 120 min. 8 to 30 min. 15 to 60 min. 8 to 30 min. 15 to 60 min. 30 to 60 min. 30 to 60 min. 1 to 2 fl. dr. 1 to 2 fl. dr. 1 to 4 fl. dr. | to 1 gr. 2 to 8 min. i to 1 gr. \ to f gr. 1 to 5 min. 8 to 30 min. t£o to eV gr- \ to 8 min. ih to £> & r - 15 to 45 gr. 1 to 4 dr. 15 to 30 min. 30 to 120 min. 15 to 80 min. 1 to 4 fl. dr. 1 to 2 fl. dr. 15 to 30 min. 15 to 60 min. 15 to 60 min. ABOUT DRUGS. 417 Remedies. Syrup ferri oxi'di sacch. " hypophosph hypophosphitum. . . c ferro ipecac krameriae lactucarii rhei " arom rosae rubi sarsap. comp scillae " comp.. ...... senegas sennas Taraxacum, extr fl. extr Terebene Terebinthina oleum Terpine Terpinol , Thalline Theina, and salts , Tiglii oleum Tincturae, see drugs .... Toxicodendron, fl. extr. Trit repens, fl. extr. . . Tritur. elaterini Urethan. Ustilago, fl. extr Uva Ursi, fl. extr , Valeriana abstr extr , fl. extr tinct " ammon Veratrina Veratrum Vir., abstr. . . extr fl. extr tinct , Viburnum, fl. extr Vina, see drugs , Xanthoxylum, fl. extr. . , Zingiber , Single Adult Dose. Metric Weights and Measures. 2 2 4 4 4 4 4 4 2 1 4 4 0.300 2 0.30 0.500 0.30 200 0.100 60 10 0.06 4 8 0.120 1 2 2 1 0.300 2 4 4 1 50 20 0.10 0.20 4 1 0.500 4 C. c. 4C. c. 4C. c. 4C. c. o 15 C. c o 15 C. c. 08C. c. o 15 C. c. o 15 C. c. 08 C. c. 08 C. c. o 15 C. c. o 4 C. c. o4C c. 08C. c. o 15 C. c. o 1 Gm o 8 C. c. o 1.30 G. c. o 2 Gm. olC.c. o 600 mGm 120 mGm o 1 Gm o 300 mGm o 100 mGm o0.30 C. c. o 15 C. c. o 30 mGm. o 2 Gm. o 4 C. c. o 4 C. c. o 4 Gm o 2 Gm o 1 Gm o 4 C. c. o 8 C. c. 08 C. c. o 6 mGm o 250 mGm o 60 mGm o 0.50 C. c. o lC.c. 08C. c. o 2C. c. o 2 Gm Old Apothecaries' 1 Weights ind Measures. 1 fl. dr. 1 fl. dr. lfl. dr. 1 fl. dr. *to 4 fl. dr. h to 4 fl. dr. 1 to 2 fl. dr. 1 to 4fl. dr. 1 to 4 fl. dr. 1 to 2 fl. dr. 1 to 2 fl. dr. 1 to 4 fl. dr. 30 to 60 min. 15 to 60 min. 1 to 2fl dr. 1 to 4 fl. dr. 5 to 15 gr. 30 to 120 min. 5 to 20 min. 8 to 30 gr. 5 to 15 min. 3 to 10 gr. 2 to 1 to ito 2gr. 15 gr. 5 gr. *gr- 1 to 5 min. 1 to 4 fl. dr. \ to \ gr. 2 to 30 gr. 15 to 60 min. 30 to CO gr. 30 to 60 gr. 15 to 30 gr. 5 to 15 gr. 80 to 60 min. 1 to 2 fl. dr. 1 to 2 fl. dr. tht to T \ gr. 1 to 4 gr. 1 to 1 gr. 1 to 8 min. 3 to 15 min. 1 to 2 fl. dr. 15 to 30 min. 8 to 30 gr. 418 ABOUT DRUGS. Single Adult Dose. Remedies. Metric Weights and Measures. Old Apothecaries' 1 Weights and Measures. Zingiber, fl. extr 0.50 to 2 C. c. 60 to 200 mGm 1 to 4 C c. 50 to 100 mGm 30 to 100 mGm 30 to 100 mGm 60 to 600 mGm 5 to 10 mGm 1 to 2 Gm 60 to 400 mGm 8 to 30 min. oleores 1 to 3 gr. tinct Zinci acet brom 1 to 2 gr. \ to 2 gr. i to 2 gr. 1 to 10 gr. tV to \ gr. 15 to 30 gr. 1 to 6 gr. iodid oxid phosphid v sulphas, emetic valer PART IV. PHARMACY, PART IV. PHARMACY. CHAPTER LXXVI. THE GENERATION AND APPLICATIONS OF HEAT FOR PHARMACEU- TICAL PURPOSES. 1349. The nature and sources of heat have been discusse.d in Chapter XV of Part I. Thermometry, the distribution of heat, the expansion of bod- ies under the influence of heat, and the relation of heat to the three states of aggregation of matter were sufficiently treated of in Chapters XV to XX, inclusive. The student is advised to again refer to those chapters at this stage of his progress. 1350. Among the useful effects and applications of heat in pharmaceutical operations are these: 1, to dry drugs, chem- icals and pharmaceutical preparations; 2, to aid the solution of solids; 3, to facilitate the extraction of the soluble constituents of drugs by digestion or decoction; 4, to remove albumin from solutions of extractive by coagulation; 5, to destroy ferments; 6, to hasten evaporation; 7, to vaporize substances in distillation and sublimation; 8, to accomplish fusion; 9, to effect calcination; 10, to induce chemical reaction. 1351. Damaging effects of heat. — Heat is liable to pro- duce damaging effects upon drugs, chemicals and pharmaceuti- cal preparations under certain conditions. In the presence of moisture, heat may induce discoloration, mould, fermentation or putrefaction, in organic drugs or preparations containing gum, pectin, starch, sugar, albumin and various other constituents. Heat causes chemical changes in many organic compounds, 431 422 PHARMACY. such as alkaloids and glucosides, and may even entirely destroy sensitive constituents of organic drugs. Valuable volatile con- stituents are dissipated by exposure to heat. In the extraction of drugs with watery menstrua, by the aid of heat, starchy matter, which is wholly inert and therefore objectionable, may be dissolved out. Heat expels water of crystallization, causing certain salts to effloresce. Various other unfavorable effects are produced by temperatures not much above moderate heat. Higher temperatures are of course correspondingly destructive. 1352. Fuel. — Substances of organic origin which are comparativelv readily ignited, burn rapidly and produce a large amount and high degree of heat, are used as fuel. These substances may be either solid, liquid or gas- eous. Their principal constituent elements are C and H. To be available as fuel, they must of course be obtainable in sufficient quantities at moderate cost. The products of the combustion (667) of fuel must be gaseous, little, if any, solid residue remaining. I 353« The amount of heat produced by the combustion of any particular kind of fuel is constant without reference to the method of combustion (or oxi- dation)— whether the fuel be burnt with oxygen, air, or a metallic oxide. 1354. The intensity of heat, or the temperature (314) produced by the combustion of any given kind of fuel, depends upon the rapidity with which the fuel is oxidized. I 355- Among the solid fuels are wood, charcoal, anthracite, coke, and soft coal. Among the liquid fuels are coal oil and its products (particularly gaso- line), fixed oils and alcohol. Among gaseous fuels are the gaseous hydro carbons, of which the com- mon coal gas is most familiar; "natural gas," which is also composed of hydrocarbons (mainly marsh gas), affords more intense heat than the artificial gas. Fuel gas, which is hydrogen mixed with carbon monoxide (produced by the decomposition of water by passing steam over coal heated to an tntense temperature) (676), is even better than natural gas; and hydrogen, as already stated elsewhere (670), produces in its decomposition the highest temperature obtainable. PHARMACY. 423 1356. The quantity of heat obtainable from the perfect combustion of any particular kind of fuel is expressed in " heat units " or thermal units (335). The following table gives the heat units obtainable from the most import- ant fuels: Hydrogen. Carbon.. . . Marsh gas Olefiant gas Crude petroleum. . Wax Tallow .. Alcohol Carbon monoxide. Burnt to water " to carbon dioxide. .. . " carbon monoxide. . . to carbon dioxide and water " carbon dioxide, Heat Units. 34 462 8,080 2,474 I4-675 11,849 10,190 10,496 9,000 7,i83 2,403 Water E7>aporatcd. 62.66 14 69 4-50 26.68 21 55 18 53 19.04 16.37 13.06 4-37 It will be observed from the foregoing table that the greatest amount of heat is produced by fuels containing the greatest proportion of hydrogen; but the maximum amount of heat which might theoretically be obtained is never attained practically, because the combustion is never complete when solid fuel is used; seldom when liquid fuel is employed; and not always even when the fuel is gaseous. 1357. The intensity of heat produced may be promoted by a full supply of oxygen or air, as by a good draft or the use of the bellows. The heat may also be intensified to some extent when solid fuel is used, by reducing the fuel to smaller pieces. Thus a pound of wood in the solid block and a pound of shavings of the same wood, produces the same amount of heat; but the shav- ings a more intense heat. For many operations a steady, well-sustained heat is neces- sary. Hard coal is the best fuel to this end. 1358. Various kinds of heating apparatus employed for pharmaceutical purposes must of course depend upon two things — the kind of fuel employed and the uses to which the apparatus is to be put. It is not the purpose of this elementary- work to describe such apparatus. We will only mention that in chemical manufacturing establishments and in operating upon large quantities of material, open furnace fires are often used; stoves of various patterns are also extensively used for pharma- ceutical purposes; and that for most of the ordinary purposes of the pharmacist, gas stoves and burners are the most serviceable 424 PHARMACY. wherever gas can be had, whilst, where gas is not obtainable, gasoline stoves and burners, and spirit lamps are the best. 1359. Steam heat, which is extensively employed in manufacturing establishments, is so effective because of the large amount of latent heat of steam and further, because of the fact that the temperature of steam does not exceed ioo° C. (212 F.), except when under pressure. The steam is applied either by means of coil submerged in the liquids to be heated, or by means of steam-jackets. By a steam-jacket is meant the space between the double shell of a kettle or pan, there being a larger shell rivited to the bottom of the vessel, so that steam can be introduced between the two shells. Hot water coil is also sometimes the best'means of keeping vessels and their contents warm in certain special operations, as, for instance: in coating pills, etc. 1360. Among the gas burners, of which there is an almost infinite variety, some afford a large flame which may be applied to a considerable surface, and are, at the same time, furnished with supports for the vessels to be heated; while others give a narrow or pointed flame. Of the lat- ter kind the Bunsen burner is the most effective. It simply consists of two tubes, the larger of which is about four inches long and carries the mix- ture of gas and air which is ignited at the top of this tube, the gas being supplied near the foot of and inside the larger tube by a very small tube with a pin-hole orifice. An adjust- able valve is placed at the foot of and around the larger tube, but below the top of the small, narrow tube, and through this valve the air enters. If the amount of air supplied through this valve is sufficient for the complete combustion of the gas which issues into the tube, the flame produced at the top is bluish and affords intense heat, whereas if the valve is partly or entirely closed, so that the supply of air is insufficient, the flame will be yellow, smoky and luminous, and will not afford as high a temperature. Fig. 87. PHARMACY. 425 The heat is most intense a little distance above the top of the tube or just below the middle of the flame. To prevent the dissipation of a part of the heat produced, jackets or chimneys may be placed over or around the burner. Sometimes two or more burners are combined for the pur- pose of producing a greater quantity of heat. Several varieties of gas burners are shown in figures 88 to 94. Bunsen burners. Figs. 88 to 94. 1361. Coal-oil and gasoline stoves are of various sizes, from the kitchen range down to a small lamp are now manufactured, which are smokeless, nearly odorless, and afford very high tem- peratures. 1362. The spirit lamp is by far the most cleanly and gen- erally useful small heating apparatus for the 'laboratory or the dispensing counter. It affords high temperatures without smoke, soot, or any disagreeable odor; and if the wick of the spirit lamp consist of loosely twisted cotton yarn, it can be spread so as to afford a flame of large diameter if desirable. 1363. For the control and distribution of the heat, various devices are employed. One of these consists simply of wire gauze through which flame does not pass, so that when a gas burner is used the gas may be lighted either above or below the wire cloth, while at the same time the gas and its flame is 426 PHARMACY. spread over a greater surface. This wire gauze may at the same time serve for a support for flasks, beakers and other ves- sels. (See Fig. 95). 1364. The sand-bath con- sists simply of an iron dish con- taining sand, and is also used for the purpose of distributing heat more evenly. It may be deep, so that flasks and retorts, when placed in it, may be entirely surrounded by the hot sand; or it may be shallow, so that flasks, beakers or dishes placed in the sand are heated only over the bottom and can at the same time be raised, the sand being allowed to run down under them for the purpose of immediately checking too great intensity of heat. Fig. 96 and 97. Water-baths in use. 1365. The water-bath (Figs. 96 and 97) is a round vessel of copper or other suitable material in which water may be PHARMACY. 427 heated to any required temperature up to its boiling point. Vessels to be heated by means of the water-bath are placed on top and serve as covers. The water-bath should be only about two-thirds full, and the dishes placed over it should not fit so closely as not to permit the escape of the steam generated when the water is boiling. As the boiling-point of the water is con- stant, it follows that the dish and contents placed over the water- bath can not be heated any higher than just below that temper- ature. 1366. Glycerin-baths, oil-baths and solution-baths are also useful, each affording high temperatures. The advantage in using these several kinds of baths, except the sand-bath, is not merely to distribute the heat, but also to limit its intensity. Thus, while the water-bath affords a temper- ature not exceeding 90° to 96 C, the glycerin and oil baths impart a heat not exceeding about 2oo°C, and the saturated solutions of salt afford various maximum temperatures, accord- ing to their character (394). 1366. The following table of the effects of certain temper- atures will be found convenient for reference: Effects of Certain Temperatures. Freezing point of water Maximum density of water Standard temperature for sp.gr Common room temperature, about Fermentation active at about " Gentle heat," U. S. P Blood heat Boiling point of stronger ether Starch forms paste with water at about Albumen coagulates at about Boiling point of alcohol Water-bath heat, about Boiling point of water Oil-bath heat, about Glycerin-bath heat, about F. o.° + 32. ° +4-° 39- °2 15. 59 ° 20.° to 22.° 68 to 71. °6 25-° 77-° 32. ° to 38. ° qo to 100. ° 37-° 98.* 37-° 98 °6 60. ° 140. ° 60. ° 140.° 78.° 172 °4 9 o.° 194. ° 100. ° 212.° 200. ° 392° 200. c 392-° 4-2S PHARMACY. Dry Processes Requiring Heat. 1367- Desiccation means simply the drying of drugs and chemicals not involving their decomposition nor the loss of water of crystallization. 1368. Fusion (376) is simply the liquefaction of solids by the aid of heat, which is frequently accomplished either for the purpose of inducing chemical reaction, as in the preparation of the iodides of arsenic and sulphur, or to render an intimate inter- mixture of several substances possible, as in making ointments, plasters, etc. 1369. Exsiccation means the expulsion of water of crystal- lization (120 to 124) from crystallized salts by the aid of heat. Among the pharmacopceial preparations which are exsiccated or dried, are sulphate of iron. alum, carbonate of sodium, and others. I 37°- Ignition is a term used to designate the heating of any solid or mixture of solids to a very high temperature in contact with the air for the purpose of causing chemical changes, the product sought being a fixed residue. When the ignition includes rapid oxidation (1003) with the aid of some oxidizing agent (1006) as with a nitrate, but without explosion, the process is sometimes called deflagration. This is illustrated in the preparation of sodium arsenate (1005). The ignition is called incineratio7i when organic substances are burnt to ashes, the product sought being one or more of the constituents of the ash. When organic substances are strongly heated with a very limited supply of oxygen or air, so that a charred residue remains, consisting largely or entirely of carbon, the ignition is called carbonization. The term torrefaction has been used to designate the partial decomposi- tion of certain organic drugs by dry heat for the purpose of destroying some of their constituents without injuring others. Torrefied rhubarb retains the astringent effect, but does not have the cathartic properties of rhubarb. The author has never seen torrefied rhubarb, and is not aware that it is ever used. 1371. Oxidation and reduction by means of dry heat have been referred to in Chapter LVIII of Part II. The term roasting is sometimes applied to the ignition of metallic sulphides and certain other inorganic compounds in free access of air for the purpose of causing their oxidation. Thus antimony sulphide may be roasted until both the antimony and the sulphur are oxidized, the sulphur forming the gas S0 2 , PHARMACY. 429 which passes into the air, and the antimony forming Sb 2 3 , which is the product sought. 1372. The definition of the process of calcination as usually given would seem to include many different chemical decompositions by dry heat, includ- ing oxidation by roasting, the conversion of sulphate or oxalate of iron into ferric oxide, the incineration of bone to make bone ash, the conversion of sodium phosphate into pyro-phosphate, mercury nitrate to mercuric oxide, etc. The usual definition is: "the process of separating volatile substances from fixed inorganic matter by the application of heat without fusion." Others again say that it is "strongly heating inorganic crystalline substances with a view to the removal of water, C0 2 , or other volatile constituent." But the term calcination is derived from the word calx, which means lime, and has reference to the process by which lime-stone is converted into lime (777). The use of the term calcination should, therefore, be limited accord- ingly, and the true definition of Calcination is the conversion of metallic carbonates into metallic oxides by the influence of strong heat. The product is always the fixed residue, which is an oxide, while the bye-product is either C0 2 alone, or C0 2 and water. The most familiar examples of calcination are furnished by the preparation of lime, magnesia, and zinc oxide. *373- Destructive distillation or dry distillation is the decomposition of solid substances by heat, the solids being con- tained in retorts or cylinders connected with receivers in such a manner that the volatile products of the decomposition can be collected. Thus, in the manufacture of acetic acid, billets of oak wood are enclosed in large iron cylinders and there heated, air being excluded so that the wood, instead of undergoing com- bustion, is decomposed by the high temperature with the for- mation of acetic acid besides very many other products. The acetic acid thus produced vaporizes, distills over, and is col- lected in the receiver as pyroligneous acid, which is simply impure acetic acid. 1374. Sublimation (377 and 406) as a pharmaceutical proc- ess is the vaporization of solids by heat under such conditions that the vapor is collected and condensed back to the solid state. The object of sublimation is to separate volatile from fixed sub- 43° PHARMACY. stances, and it may either be one of the steps in the process of production of a volatile solid, as in the preparation of calomel and corrosive sublimate (794), and in the separation of benzoic acid from benzoin, in which that acid is contained naturally; or the sublimation may be a method of freeing a volatile substance from fixed impurities, as in the resublimation of camphor and iodine. CHAPTER LXXVIL COMMINUTION. 1375. The disintegration or comminution of solids is a necessary preparatory step in many pharmaceutical operations. For the preparation of mixed species (1536) most of the crude drugs which enter into them are required to be cut or crushed, and cut or crushed drugs are also frequently employed for mak- ing infusions, decoctions, solid extracts, certain tinctures, wines, vinegars an'd syrups, etc. Solids occurring in large masses or pieces, or in large crys- tals, must be reduced to smaller particles for purposes of extrac- tion or to hasten solution. 1376. Among the various kinds of comminution or mechan- ical division are cutting, slicing, chopping, rasping, grating, con- tusion, grinding, trituration, levigation, elutriation, granulation, etc. Nearly all of these terms are self-explanatory. 1377. For cutting, slicing and chopping plant drugs it is necessary to employ sharp edge-tools to avoid tearing or crushing and the consequent formation of powder. In many cases it is desirable to produce clean-cut, uniform pieces free from powder. Starchy roots and drugs of friable texture, as, for instance, althaea and rhubarb, when required for extraction PHARMACY. 431 by maceration or digestion for the preparation of infusions or syrups, should not be cut with dull knives producing ragged fragments or shreds mixed with loosened starch granules, which render the product unclear. Pruning knives and shears, the ordinary tobacco cutter and good hash knives are, when well-sharpened, useful instruments for cutting-plant drugs. 1373. Rasping and grating are applicable in a few cases, and are accomplished by means of large, coarse, half-round rasp and the ordinary graters used for culinary purposes. 1379. Crushing and grinding, producing very coarse pow- der, is effected by means of iron hand-mills. These drug mills are constructed upon the same general principles as the large coffee mills of the grocery stores, and are capable of reducing a great variety of drugs to a moderate degree of disintegration. The drug to be passed through the iron drug-mill must first be broken or chopped if in pieces too large to pass between the grinding plates without difficulty, and it is frequently necessary to pass the same lot of drug through the mill several times in succession, setting the mill finer each time, before the powder is of the required degree of fineness. But fine powders can not be made by the use of the hand-mill alone (1382). 1380. Drug mills driven by steam-power, such as Mead's disintegrator, grinding mills of iron, roller mills, burr mills, chasers, pot mills, etc., which are used only by drug millers and manufacturers, will not be described here. 1381. The iron mortar and pestle are extremely useful to the pharmacist who desires to prepare his own powdered drugs as far as practicable, for percolation and for other purposes. The iron mortar, in order to be of great practical use, should be of at least six gallons' capacity. It must have a solid, heavy, iron pestle of perfect form and size to match the mortar (1384), and the grinding surfaces must be polished by powdering emery or sand until perfectly clean and lustrous. The top of the 43 2 PHARMACY. mortar should be flaring. It is much deeper than mortars intended for any other use, except that commonly employed for pre- paring mixture of almond. (Fig. 9 8.) As the iron mortar is very heavy, and great force is expended in contusion (1383), it must stand firmly upon a block or pillar, rest- ing not upjon the floor but on the Fig. 98. ground. 1382. With an iron mortar of from six to eight gallons capacit) it is not difficult to make quite five powders of nearly all kinds of drugs, if the quan- tity put into the mortar at one time be not greater than just enough to cover the bottom. When a plant drug is to be reduced to fine powder it is gener- ally best to run it through the iron mill first, and then to powder it in the iron mortar. %3%3- To break, bruise, crush or powder a substance in a mortar by means of blows with the pestle is called contusion. The directions in which the force is applied must depend upon the nature of the substance operated upon, but when pulverization is the object the blows must be accompanied by a grinding and sliding motion. 1384. Any mortar must have a perfect, smooth, regular, spherically concave bottom. It must be of a sufficiently hard material of uniform and compact texture, neither porous, slip- pery, nor brittle. The convex surface of the head of the pestle should be of perfect form — neither flattened, pointed, nor irregular — and of a somewhat smaller radius than the curve of the grinding surface of the mortar, so that, while there can be but one point of contact, the divergence of the surrounding interval between mortar and pestle will be quite gradual. Fig. 99 shows a proper relation between the grinding A small powder mortar. sur f aces of mortar and pestle. In mortars used specially for triturating (1385 and 1386) powders, the head of the pestle may be somewhat more flattened. Fig. 99. PHARMACY. 433 1385. Trituration is the grinding produced in the mortar by a rotary motion of the pestle accompanied by pressure. The pestle is grasped firmly, the whole hand being used for the purpose. Small amounts of brittle solids can be reduced to fine powder by tritura- tion, and some substances which are not brittle can be powdered in the same manner, provided their disintegration is aided by the addition of a small quan- tity of some unobjectionable volatile solvent, as when camphor is powdered by trituration with the aid of a little alcohol or ether, or when lactucarium is powdered with the aid of chloroform, or iodoform with the addition of ether. Certain soft or tough solids may be powdered by trituration with hard substances, as when vanilla or fresh orange peel is rubbed to powder with sugar, or when abstracts and triturations are made with milk sugar. 1386. Trituration is also employed for mixing powders, or to powder and mix substances at the same time. For these purposes the trituration is best performed by moving the pestle in circles, beginning near the center of the mortar, enlarging the circles toward the circumference, and returning toward the center again by gradually diminishing the diameter of the circles described. 1387. When dry substances only, already in fine powder, are to be mixed by trituration, pressure is unnecessary, and when the substances triturated are liable to adhere to the mortar and pestle, as in the case with resins, gumresins, camphor, alkaloids, and several other kinds of dry solids, no pressure should be applied. 1388. Mortars and pestles are also used for massing the ingredients in the prepara- tion of masses, troches, and pills, for preparing small quantities of solu- tions, making liquid mix- tures and emulsions, in the preparation of certain oint- Figs. lootoioa. Pill mortars, ments, cerates, and suppositories, and for many other purposes. Various kinds of mortars are employed. Shallow mortars of large diameter are the best for mixing powders and ointments; 434 PHARMACY. small, rather deep strong mortars are used for making pill masses; larger and still deeper lipped mortars for making liquid mixtures and emulsions, etc." Mortars and pestles are made of wedgevvood composition, porcelain, glass, and various other materials. Porcelain mortars are either glaz - ed or unglazed, each kind being useful for its Figs. 103 ana 104. Mixture mortar and pestle. Own Special purposes. Pill mortars of iron are not uncommon. Fig. 98 to 104 represent different kinds of mortars. 1389. The spatula is as indispensable in pharmacy as the mortar and pestle. They are made of steel, platinum, silver and horn. Steel spatulas are the most useful because flexible and elastic; but the other materials are preferred in operating with substances which attack steel, as is the case with many chemicals. Spatulas are used not only to transfer substances from the shop bottle to the balance pan, or from one vessel to another, but to scrape off or scrape together substances adhering to mortar or pestle for the purpose of rendering possible the uni- formly intimate intermixture of the ingredients. In the preparation of some ointments, and even some com- pound powders, the spatula and slab may be preferable to the mortar and pestle. 1390. Levigation is the trituration of substances to a fine state of divis- ion by means of a slab and muller, as paints are sometimes mixed, a liquid of some kind being added to the solid matter which is to be thus rubbed fine, so as to produce a soft paste. Water, alcohol and oil are used for this pur- pose. Sometimes the lexigation also involves purification, as when an insol- uble solid is triturated with water not only to reduce it to a finer powder but also to wash out any water-soluble impurities. 1391. Elutriation is a process sometimes employed to separate fine PHARMACY. 435 powder from coarse particles. It is applicable only to inorganic substances heavier than water and insoluble in that liquid. It consists in agitating the powder with a large volume of water, desisting while the coarser particles subside, and decanting into another vessel, the liquid holding the finer pow- der in suspension, after which this powder is allowed to deposit on the bottom and is then collected. Levigation usually precedes elutriation, and the substance which is to be thus powdered and sifted is subjected to these two processes alternately until the requisite amount of fine powder has been obtained. The product may be made extremely fine. Prepared chalk and purified antimony sulphide are elutriated. 1392. The granulation of salts is effected by several different methods, which will be described later (1489). J 393* The powders produced by all of these several meth- ods are far from uniform. The greatest attainable uniformity of division is probably attained by trituration and by leviga- tion, whilst powders obtained by contusion and by grinding consist of particles of various sizes, some of them several times as large as others. To regulate this w r ant of uniformity as far as practicable the coarser particles are separated by means of sieves, the meshes of which are small enough not to admit of their passage through the sieve cloth with the finer particles. But this method can not, in the nature of things, produce a uniform degree of fine- ness in the powder obtained, for every particle of the drug can not be subjected to precisely the same treatment, and plant drugs are not of exactly the same texture throughout, so that the more friable tissues are not only powdered first but also reduced to a finer state of division than the tougher tissues. Thus a powder made to pass through a sieve of 40 meshes to the linear inch may consist of about equal proportions of mod- erately coarse, moderately fine, fine, and very fine powder. 1394. This inequality of size of the particles of pow T der can not be remedied by sifting off the finest, as by passing the powder first through a sieve of 40 meshes to the inch and then through another of 50 meshes to the inch, for the obvious reason that it is altogether impracticable to reject the bulk of the drug, 436 PHARMACY. and also for the still more potent reason that it frequently hap- pens that the finer powder consists of the most active portions of the drug, the tougher portions, which are last reduced to powder and form coarser particles, containing a greater propor- tion of woody fibre or other inert matter. 1395. From what has been stated in the preceding para- graph it will be readily understood that whenever a drug is powdered two conditions must be fulfilled in order to obtain a proper product, viz.: 1. The entire quantity put in the mill or mortar must be reduced to powder, and 2, the powder obtained must be well mixed before any portion of the product is taken away. 1396. Comparatively coarse powders are employed for mak- ing extracts, such as infusions, tinctures, fluid extracts, solid extracts, abstracts, etc., while very fine powders are necessary for the preparation of compound powders, pills, troches, etc. Powders administered as such, or entering into medicines as such, can not be too fine. 1397. The relative fineness of powders is indicated in the Pharmacopoeia by means of numbers referring to the meshes in the sieve cloth. Thus a powder which passes through a sieve cloth having 80 meshes to each linear inch is called a No. 80 powder ; one that passes through a sieve cloth of 40 meshes to the linear inch is a No. 40 powder, etc. No. 80 powder is called "very fine"; No. 60 powder is referred to as "fine"; No. 50 is ''moderately fine"; No. 40 "moderately coarse"; and No. 20 is "coarse" powder. 1398. The sieves used by pharmacists for ordinary pow- ders are usually made of brass wire cloth if coarse, or of silk if fine. The sieve frames are generally circular. Sometimes they are provided with covers above and beneath to prevent the dust from rising, and they are then called " drum sieves." 1399. Dusted powders are produced by chaser mills, and are so called because they are so fine as to rise like dust with the currents of air created by the revolutions of the mill stones, and are deposited on the floor outside of the tall iron cylinder surrounding the stones, or on shelves in the mill box. PHARMACY. 437 1400. Very friable masses, such as magnesium carbonate and bismuth subnitrate, are powdered by simply rubbing them gently against the cloth in a- sieve. 1401. Colored substances become lighter in color when powdered, and their color grows lighter as the powder gets finer. CHAPTER LXXVIII. SOLUTION IN PHARMACY. 1402. In Part I, Chap. X, a brief account was given of the nature of solution, the difference between simple and chemical solution, the miscibility of liquids, solvents and solubility, etc. The student should here refer again to that chapter. 1403. To dissolve solids most expeditiously they are first crushed or powdered, so that the surface exposed to the action of the solvent may be increased. Another effective means of facilitating solution is agitation. Stirring or shaking the solvent together with the substance which is to be dissolved insures more rapid solution because it brings each portion of the one in contact with fresh portions of the other. If a solid substance resting on the bottom of a vessel be covered with a sufficient amount of the proper solvent, and the solution allowed to proceed at perfect rest, the solid would soon be enveloped in or covered up by the solution first formed at the surface of contact, and this solution, interposing between the solid and the remaining portion of the liquid, would retard the process, but agitation would at once distribute the dissolved matter throughout the whole body of liquid. 1404. To bring the solid in contact with new portions of solvent successively the solid may be placed in a perforated dish or basket, or in a loose bag, or on a colander or perforated diaphragm, just below the surface of the solvent, so that the solution may descend to the bottom of the vessel as fast as it is 438 PHARMACY. formed, other portions of liquid at once occupying its place in contact with the solid. This is called circulatory displace- ment. 1405. That the application of heat generally hastens the solution of solids will be easily understood from the fact that the solid must take up latent heat (311) in order to become liquefied (385). A warm or hot solvent generally dissolves a larger quantity of solid matter, and dissolves it more rapidly than a cold solvent. Thus 200 ounces of boiling- water will hold 100 ounces of potassium chlorate in solution; but when this solution is allowed to cool to the ordinary room temperature, only about 12 ounces of the salt will remain in the liquid, 88 ounces having crystallized out as the temperature gradually decreased. 1406. But heat does not invariably aid the solution of solids, for common salt (sodium chloride) does not dissolve better in hot water than in cold, and the same is true of calcium hydrate, acacia, and a limited number of other water-soluble solids. Nor is the difference between the solubility of a solid in a hot solvent and its solubility in the same solvent at a lower temperature generally as great as in the case of potassium chlorate in water as described in the foregoing lines. 1407. Maximum solubility. — Experimental results with numerous bod- ies would seem to indicate that each substance is soluble in the greatest pro- portion in any given solvent at some fixed temperature being soluble in less amount either above or below that temperature. A most striking example is furnished by sodium sulphate, which reaches its maximum solubility at i5. c 6C. (6o r F.), the solubility decreasing on either side of that point so that at ioo c C. (212 F.) the solubility is nearly the same as at o. c C. (32 F.) 1408. A solution of one substance may be an effective solv- ent for another substance (188). Thus, aloes is entirely soluble in four times its weight of boiling water, because some of the constituents of the aloes which are insoluble in pure water are nevertheless soluble in a strong water solution of the other con- stituents of the drug; but this strong solution of the whole of the aloes in four times its weight of boiling water can not be diluted by the addition of more water, hot or cold, without PHARMACY. 439 becoming turbid, and if a sufficient quantity of water be added the greater part of the dissolved matter will separate. 1409. Compound solution is a term often employed. It is synonymous with the expression chemical solution (190). At the same time the title compound solution is also used to designate pharmaceutical solutions containing more than one ingredient aside from the solvent, as for instance the ''compound solution of iodine" containing iodine and potassium iodide. 1410. In paragraph 188 a definition was given of a sat- urated solution. We will now add that a solution of a solid, saturated at a given temperature, is not saturated at a higher temperature, and a solution of gas saturated at a given tempera- ture is no longer saturated when the temperature is lowered. 141 1. But we may have a super-saturated solution in many cases, when the solution of a solid is made saturated at any temperature and then slowly cooled a few degrees lower, no separation resulting. The solution thus formed may contain or retain a larger quantity of dissolved matter than it would have been possible to dissolve in the solvent except at a higher temperature than the solution now has. A super-saturated solution of sodium sulphate may be made which will remain free from deposited salt for an indefinite period if kept at abso- lute rest, but which contains so large an amount of the salt in solution that when it is suddenly agitated, or when a crystal is dropped into it, the entire solution solidifies into a crystalline salt mass. But tnis is an exceptional case. 1412. Partial solution is of very frequent occurrence in pharmaceutical operations. Mixtures of solid substances, or drugs of a heterogeneous structure or composition, such as the plant drugs, are generally only partially soluble in any one solvent. Thus a gum-resin yields its resin to alcohol but not its gum, whereas it yields to water its gum but not its resin. Roots, barks, leaves and other plant parts yield different substances to different solvents, so that both the composition and the amount of the extract obtained differ according to the menstruum employed. 44° PHARMACY. 1413. When mixtures of soluble and insoluble inorganic substances are separated from each other by the solution of the soluble contents, this process is called lixiviation. The most familiar illustration of lixiviation is the extrac- tion of the potassium carbonate from wood ashes by treating the ashes with water. 1414. Fractional solution. — The application of different solvents, one after the other, for the purpose of separating substances of different solu- bilities, is sometimes called fractional solution. The two or more solvents used may differ only in temperature, or in strength. 1415. To facilitate the solution of gases in water, cold and pressure are applied. Cold water dissolves more chlorine than warm water; to charge " carbonic acid water" with as large a quantity of the gas C0 2 as practicable, the water must be chilled and the gas must be forced into a strong " fountain " where it is agitated with the water, the amount of gas dissolved being in direct ratio to the pressure imposed. When the pressure is removed by opening the " fount- ain," C0 2 rushes out of the solution. If the carbonic acid water be heated all of the " carbonic acid gas " will be expelled. 1416. The solution of liquids in other liquids is a common phenom- enon. Many liquids are miscible with each other. A mixture of glycerin and water is as truly a solution as the not more homogeneous liquid obtained by dissolving sugar in water. Again, some liquids are soluble in their proper solvents only to a limited extent, as is the case with the volatile oils in reference to alcohol. Finally, we can dissolve a limited quantity of ether in water, and per contra a limited quantity of water in ether, and these two different solutions do not mix with each other. A saturated solution of carbolic acid in water is not miscible with a satu- rated solution of water in carbolic acid. 1417. The most important solvents used in pharmaceutical operations are: water, alcohol, ether, chloroform, glycerin, volatile oils, carbon disulphide, fixed oils, and solutions of the acids and alkalies. 1418. Water ao a Solvent. — Water is the most valuable of the simple solvents. Its solvent powers are great, it is itself entirely neutral, and it is universally present and easily obtain- able in a state of purity. 1419. Water-soluble Substances. — Of the numerous sub- stances which are more or less soluble in water, many are neces- sary to the existence of plants and animals, and others are of the utmost importance in the arts and manufactures. PHARMACY. 441 Among the water-soluble organic substances are: Sugar, gum, the normal albuminoids, and many organic acids. In addition to these groups, an infinite variety of complex organic bodies, as the tannins, a great number of glucosides and other neutral principles, and most of the alkaloidal salts, are also water- soluble. Among the water-soluble inorganic substances are: the alkalies, the stronger acids, and most of the salts. Thus the compounds of potassium and sodium are with but few exceptions readily soluble in water; the nitrates are soluble, except the normal nitrates of mercury and bismuth, which are decomposed by water, and the basic nitrates of the same metals which are insol- uble; the normal acetates are all soluble; the chlorides are sol- uble, except calomel and the chloride of silver; and many iodides, bromides, cyanides, sulphates, etc. 1420. Substances insoluble in water. — Among the organic substances insoluble in water are: Cellulose, normal starch, coagu- lated albuminoids, resins and fixed oils; the volatile oils are sparingly soluble; and free alkaloids are generally very spar- ingly soluble. The morganic substances insoluble in water include all the solid, non-metallic elements, the metals, the oxides, sulphides, carbonates, phosphates and oleates of the heavy metals, and a number of other compounds. 1421. Liquores. — The "liquores" or " solutions" of the Pharmacopoeias of the United States, Great Britain and Germany, are aqueous solutions of non-volatile substances, mostly inor- ganic chemicals. 1422. Alcohol as a Solvent. — Alcohol ranks next to water as a simple solvent. It is indispensable in the arts and manu- factures. Instead of being absolutely inactive, however, as water is, alcohol, when introduced into the body of man or animal, produces marked effects which greatly limit its usefulness. 442 PHARMACY. 1423. Alcohol-soluble Substances. — Alcohol dissolves resins, volatile oils, most of the free alkaloids, and many of the neutral proximate principles of plants. It also dissolves the alkali-hydrates, some chlorides, iodine and a few other inorganic substances. 1424. Substances insoluble in alcohol. — Cellulose, gums, starch and albuminoids are insoluble in alcohol. All the fixed oils are insoluble in that liquid, except castor oil and croton oil. Alkaloidal salts are generally far less soluble in alcohol than in water. Inorganic salts are mostly insoluble in alcohol. 1425. Ether as a Solvent. — Ether is an effective solvent for fixed oils and fats, which, as has already been stated, are insoluble in water, alcohol and glycerin. Ether also dissolves certain resins, volatile oils, alkaloids, and various other organic compounds. Inorganic substances are generally insoluble in ether, as are also cellulose, starch, gum, sugar, and albu- minoids. 1426. Chloroform dissolves a great number of the alka- loids, and is also an effective solvent of fats and fixed oils, resins, and many other substances. 1427. Glycerin as a Solvent. — Glycerin dissolves a great variety of substances, both organic and inorganic. It is a specially effective solvent for tannin and organic tannin com- pounds. 1428. Menstrua. — A liquid used chiefly as a solvent, but also in part as a vehicle for medicinal substances is called a menstruum. The most common pharmaceutical menstrua are ; water, alcohol and syrup. 1429. Among the pharmaceutical solutions are: the liquores, waters, mucilages, syrups, infusions, decoctions, spirits, tinc- tures, fluid extracts, wines and vinegars. PHARMACY. 443 1430. Solutions are made in mortars, dishes, beakers, flasks, and various other vessels. When solids in a state of powder, Figs. 105 to 107. Nests of beakers. coarse or fine, are to be dissolved, beakers and flasks are prob- ably the most convenient vessels for the purpose, especially the beakers (Figs. 105 to 107). CHAPTER LXXIX. FILTRATION AND OTHER METHODS OF CLARIFYING LIQUIDS. 1431. When solutions of solids are prepared it often happens that the product is unclear from the presence of particles of dust and other insoluble solids. Many liquid extracts, as infu- sions, tinctures, etc., and other liquids, may be turbid from suspended particles of solid matter. To separate these solid particles so as to render the liquid perfectly clear, the latter is passed through some porous filtering medium, such as unsized porous paper, or paper pulp, or glass wool, asbestos, powdered glass, magnesium carbonate, calcium phosphate, charcoal, etc. This process is called filtration, and the clear liquid thus obtained by it is called a filtrate, and the paper or other medium through which the filtration is effected is called a filter. 444 PHARMACY. 1432. Filter paper is the most convenient and effective filtering medium for almost all liquids not too viscous to be filtered. There are several grades of filter paper, differing in color, purity, thick- ness, and porosity. Gray filter paper is sufficiently free from iron to be useful for the filtration of many pharmaceutical liquids, as tinctures, waters, and oils, but not suitable for the filtration of solutions of chemicals, such as acids, alkalies, and salts. White filter paper 'is always purer and sometimes absolutely free from iron and other impurities liable to be found in the gray paper. Chemical filter paper is manufactured at Grycksbo, in Sweden, which is in every way all that can be desired, leaving the least possible amount of ash when burnt. Solutions of chemicals, unless so corrosive as to attack the paper itself, can be freely filtered through good white filter paper without discoloration or con- tamination of the filtrate. But for pharmaceutical purposes, coarse, thick, very porous, white filter paper, which can be safely used for all non-corrosive liquids, and which will at the same time admit of rather rapid filtration, is the best kind. It may be had either in whole square sheets, or cut into round filters of various sizes ready for use. The latter kind is the most convenient, and at the same time the most economical, as its use involves no waste. x 433- Paper filters are either plain or plaited. A plain or simple filter is made by first folding the round paper across the center once, and then folding the double half- circle thus formed, also in the center, this second fold being opened out again; then one flap or end of the half-circle is folded in the middle so that its edge coincides with the crease which divides the half-circle in two equal parts, and the other end or flap is folded on the opposite dde also with its edge against the center crease. The paper as now folded is a quarter seg- ment of the circle. The filter is now opened out, and will be found to be of three thicknesses of paper on two opposite sides, but of only one thickness of paper on the two other opposite sides, while the perfect cone formed by the open filter fits per- fectly in a funnel of 6o° angle. Plain filters are used for collecting and washing precipi- tates, and often also for simple filtrations; bat the filtration of large quantities of liquids through plain filters is too slow, PHARMACY. 445; because this filter, when properly fitted into the funnel, lies close Figs. 108 to no. Making a plaited filter. to its sides all around so that the liquid can not pass through the paper except at the apex. Plaited filters are made as shown in Figs. 108 to 113, and are preferred to the plain filter when rapid filtration is desirable, as Figs, in to 113. Plaited filters, the plaited filter leaves a number of chan- nels between the paper and the funnel, per- mitting the liquid to run off more freely. 1434. Glass funnels fit for all pur- poses must have an angle of 60 degrees. Such funnels are the only kind in which a plain filter can be fitted snugly, and, there- fore, no other funnels can be used for col- lecting and washing precipitates, while they are as good as any other funnels for 446 PHARMACY. all other purposes. Funnels of other angles can be used for filtration with plaited filters. (See Figs. 118 and 119.) A perfect funnel should also have a regular and well formed throat, and its stem should have a beveled end so that the liquid passing out of it will form one undivided stream. (See Figs. 114, 115 and 116). H35- Figs. 115 to 119. Funnels and filter stand. The paper filter and funnel must fit each other; the upper edge of the filter should be about % to }4 inch below the top of the funnel. 1436. Filter stands are shown in Figs. 116 and 120. The stand repre- sented in Fig. 120 is also a lamp stand, but is commonly, although very improp- erly, called a u retort stand." In filtration the funnel must be so placed that its stem is within the top of the vessel in which the filtrate is collected, and the end of the stem should touch one side of the receiving vessel so that the stream of liquid may run down that side to avoid spattering. Fig. 120 also shows an inverted flask placed over the funnel to furnish a con- tinuous flow of the liquid to be filtered, and the receiving vessel is a beaker. Fig. 120. Lamp stand and continuous filtration PHARMACY 447 1437. Ribbed funnels are sometimes used to render plaited filters unnecessary. Filter- baskets are also employed for the same purpose — to provide a passage for the liquid between the filter and the fun- nel. The filter basket is a funnel-shaped frame of wood, whale- bone, or wire; it is placed in the funnel, and the filter in the basket. Or glass rods, little strips of wood, etc., may be placed between the filter and the funnel. 1438. Viscous liquids do not easily pass through filter paper, and some thick liquids can not be filtered at all. But many viscous liquids which pass through the filter only with great difficulty when of the ordinary temperature can be readily fil- tered if warmed sufficiently. Corrosive liquids must be filtered through glass, wool, coarsely powdered glass, asbestos, or sand, instead of paper. I 439- Colation or straining is the separation of solid par- ticles from liquids by means of flannel, muslin, felt and other fabrics, cotton, tow, sponge, etc. It differs from filtration only in regard to the filtering media used, which do not always produce Figs. 121 to 123. Colation; straining cloths and frames. as perfect results as filtration through paper. The liquid which passes through the strainer is called the colature. A colature is rarely as clear as a filtrate, and the clarification begun by eola- tion is often finished by filtration. PHARMACY. A tenaculum is a square wooden frame for supporting strain- ing cloths. Several such frames are shown in Figs. 121 to 125. Figs. 124 and 125. Colation. A Hippocrates* sleeve is a pointed straining bag. Such bags are made of cotton cloth or of flannel. 1440. Decantation. — In many cases the most convenient and effective method of clarifying liquids, especially when large quantities are operated upon, is to allow the liquid to stand at perfect rest a sufficient time to insure the subsidence of all the particles of solid matter which are suspended in it and make it unclear, and then to remove the supernatant clear liquid by decantation. Decantation is the process of carefully pouring off a liquid from a precipitate, a sediment, a mass of crystals, or any other substances from which it is desired to separate that liquid perfectly. 31, 354 Barometer 68 Barometric pressure 67-73 Base, physical 50 Base residues 249 Bases 133, 247, 250, 253 reactions of, with acids 253 Basicity of acids 251 Ba-ic oxides 2b5 BasylODs radicals 220, 221, 2^2 Baths 426, 427 Beakers 443 Beet-root sugar 336 Belladonna leaves 363 root 346 Belladonnine 346, 363 Benne oil 386 Benzoates276 Benzoic acid 382 Benzoin 382 Berberine 348 Berthollet's laws 297-300 Berzelius' hypothesis 136 "Bi-"292 Bibasic acids 251 Bicarbonates 268 Bichromate of potassium 270 Binary compounds 234. 291 Biniodide of mercury 245 " Bis" ^92 p ismuth and compounds 186, 190 B;smuthj'1217 [NDEX. 509 Bitter orange peel 355 tonics 393 Bivalent radicals 152, 153 Black color 100 Blackberry root bark 359 Bleaching powder 181, 262 Blennorrheas 396 Bloodroot 351 Blue flag 349 Body, definition of 1 Boiling 451 Boiling points 75, 90, 93, 94, 95, 451 Boli 478 Bonds 128, 153, 155, 227, 234 self -saturation 155 Bone Ash 201 Bones, calcined 201 Boneset 360 Borates 269 Borax 190 Boric acid 190 Boron 190 Botany 323 Brahma s press 60 Brayera 361 Brimstone 177 Britileness7 Bromides 243, 244 Bromine 181 Brucinc 272 Buchu 363, 364 Buckthorn bark 357 Ru lbs 331 Bunsen burners 424, 425 Buoyancy of fluids 61 Burners 424, 425 Butter of cacao 386 Buxine350 Bye-product 309 Cacao butter 386, 493 Calabar bean 372 Calabarine 373 Calamine 20t Calamus 346 Calcination 201, 429 Calcium and compounds 201, 202 Calcspar 19 Calisaya bark 356 Calomel 140, 2i8, 240 Calories HI Calumba 347 Calx 201 Cambogia 380 Camphor 390 Canada turpentine 384 Cane sugar 3 6 Cannabis indica 360 Cantharis 391 Capillarity 33-41, 470 Capsaicin 368 Capsicum 367 Caraway H68 Carbohydrates 287, 288 Carbolic acid 281 Carbon 138, 191 compounds 191-193 Carbon disulphide 238 group 194, 195 Carbonate^ 212, 268, 269 ) Carbonization 428 Caroonyl217^8-5 Carboxyl 2S2 Cardamom 368 Cardiac sedatives 395 stimulants 395 Cardinals 502, 503 Carminatives 395 Carrageen 374 Carum 368 Caryophyllus 362 Cascara sagrada 358 Cassia cinnamon 356 Castor oil 339. 386 Cataplasms 491 Cathartics 395 Cathartin351,366 Catechin 375 Catechu 3*5 Caustic, lunar 209 Cayenne pepper 367 Cells, electric 105 Cellulin,333 334 Cellulose 333, 534 group 288 Cement, 35 36 Center of gravity 49 Centigrade thermometer 77 Centigram 504 Centimeter, 504 506 Centrifugal force 49 Cera 385 Cerates 492 Cetaceum 385 Chains 228, 229, 277 Chalk 01 Chamomile 361 German 363 Chartse 49 Chemical affinity 8, 12, 113, 123-125 attraction 113, 123-125 changes 112, 119-123 compounds 115, 116, 139 constituents of drugs 332 decomposition 119, 127, 134 energy 113, 123-125 equations 161, 162 experiments 121. 122 force 113, 123-125 formulas 159 nomenclature 289 notation 158 phenomena 118, 119-123 polarity 125, 135 properties 118 rays of light 102 reactions 119-123, 125-131, 225 solution 439 symbols 158 Chemicals 318 Chemism 76, 113, 123, 124, 125, 128, 129, 150 Chemistry 6, 118, 133,134 organic 192 pharmaceutical 318 Chenopodium 368 Chinese cassia 357 Chlorates 261, 262 " Chloride of lime" 181, 262 Chlorides 212, 240, 241-243 of manganese 141 5 IQ INDEX. Chlorine 155, 180, 181 negative loo, 180 oxides of 141, 180 positive 155, 180 valence 177, 178 Chlorinated lime 181, 262 Chloroform 279, 442 Chlorophyll 343 Chondrus 374 Chopping 430 Chromates 270 Chrysophan 351, 366 Chrysophanic acid 351 Cirn cifuga 347 Cinchona 355, 356 Cinchonidine 356 Cinchonine 356 Cinnabar 208 Cinnamic acid 383 Cinnamon 356 Circulatory displacement 438 Cissampeline 350 Citrates 274, 275 Citric acid, 284 Clarification of liquids 450 Classes of compounds 234 Cleavage 23 Clouds 98 Cloves 362 Clusters of atoms 228 Coagulation 338 Coal 191 Coca 364 Cocaine 364 Coction 470 Codeine 377 Cod liver oil 386 Co-efficients of expansion 87 Cohesion 12, 14, 17, 130 Cohosh, black 347 Colation 447 Colature448 Colchicine 347, 371 Colchicum root 347 seed 371 Cold 73 Collection of plant drugs 328 Collunaria 494 Collyria 494 Colocynth 368 Colocynth in 369 Collodions 494 Colloids 42, 43 Colophony 3S1 Colloxylin 494 Color 100 Coloring matters 343 Colors, complementary 100 of elements 165 prismati 100 Columbo347 Combination by volume 148 Combining power 1 3, 123-125 proportions 139-143 value 150, 223 volumes 145. 146 Combustion 76, 171,301 Comminution 430 Compass 103 •Complementary colors 100 Compound matter 115. 116 molecules lio, lid, 224, 226 radicals 124, 125, 213, 214, 215 solution 439 Compounds 115,116, 139, 234 binary 234 chemicals 115, 116 classes 234 inorganic 234 insoluble 298, 299, 307, 308 organic 235 physical properties of, 168, 169 quaternary 234 ternary 234 v -latile 300 Compressibility 7 Condensers 96, '455, 456 Confections 478 Conductivity of elements 166 Conductors of electricity 104 heH 83 Congealing points 75, 90, 91 Confine 369 Conium 369 Conservation of energy 14 Conserves 478 Conspergatives 479 Constituents of drugs 332, 333 Constitutional formulas 231 Contraction bv coid 87 Convolvulin349 Copaiba 384 emulsion 483 Copper and compounds 207, 208 Coriander 369 Cornutine 374 Correlation of energv 14 Corrosive sublimate 140, 2C8, 241 Cotton-root bark 357 Cottonseed oil 385 Cream of tartar 198, 273 Crocus 362 Croton oil 339, 386 Crushing drugs 431 Crystal, quartz 30 Crystallic bodies 15, 19 Crystalline bodies 15, 19 form 15, 19, 24, 25, 28, 462 Crystallizable substances 19, 165 Crystallization 24, 25, 460, 461, 463, 464 water of , 15 Crystallizers 46 1 Crystallography 28-34 Crystalloids 42, 43 Crystals 15, 18. 28 angles of 18, 22 anhvdrous 25 axes 22, 23, 28 classification of 28 cleavage 23 development of 463 directions for extension of, 21, 22 drying of, 464 faces 18, 22, 23 forms of 22-24, 28 growth of 21, 25, 461, 462 hemihedral 23 holohedral 23 hydrous 26 nursing of 462, 463 INDEX. I I Crystals production of 25, 461 463 size of 4b i, 462 systems of 28-34 Assymraetric 34 Clinometric 28 Cubic 29 Dimetric 31 Doubly oblique prismatic 34 Monoclinic 33 Monometric 29 Monosymmetric 33 Oblique prismatic 33 Orttaometric 28 Prismatic 31 Pyramidal 31 Quadratic 31 Regular 29 Khombic 32 Rhombohedral 30 Right prismatic 32 Square 31 Tessular 29 Tetragonal 31 Triclinic 34 Trimetric 32 Cube 24, 29, 34 Cubeb 369 Cubebin 369 Cubes 34 Cubical crystals 24 expansion 87 Cub-c-centimeter 504, 505, 506 Culvers' root 350 Cupric copper 207 Cuprous copper 207 Cutch 375 Cutting drugs 430 Current electricity 105 Cyanides 246 247 Cyanogen 1S5, 217 Cydonium 372 Dalton's at©mic theory 142, 143 law of multiple proportions 143 Dandelion 353 Daphnin 358 Decantation 39, 312, 448, 449 *'Deci-"292 Decigram 5C4 Declensions, Latin 496-503 Decoction 470 vessel 469 Decoctions 486 Decolorization 45 Decomposition 5, 119, 127, 128 double 127, 307-340 Decrepitation 325 Deflagration 428 "Deka-" 29; Deliquescence 15 Demulcents 397 Density 3, 10, 11, 12 of elements 165 of water 88, 89 vapor 146 Deodorization 450 Derivatives 234 Desiccation 428 Destructive distillation 429 Dew 98 Dew point 97 Dextrin 335 •'Di-' 1 292 Diamagnetic bodies 1C4 Diamond 19, 191 Dialyser 43 Dialysis 43, 470 Diaphoretics c"96 Diatomic molecules 147, 224 Diffusion of liquids 41, 471 Dige.-tants 393 Digestion 469, 473 Digitalis 364 Digitoxin 364 Dimorphous bodies 19 Direct union of atoms 227 Dishes 451, 452 Disinfectants 397 Disintegration 430 Dispensatories 325 Dispensing 326 Displacement 471 circulatory 438 Distillate 453. 460 Distillation 96, 453-457 chemical 457 dry 429 fractional 454. 457 Distilling apparatus 453, 454 Divisibility of matter 4, 45, 141, 142 Dodekahedron 29 Dome condensers 456 Dose table c99-418 Doses 327, 39 i Double decomposition 127, 225, 297—300, 307— 310 Double sallte 258 Draft 84 Drastic purgatives 396 Drug mills 84 structure 334 Drugs 317, 320, 322 acrid 343 animal 318, 391 annual supplies of 328, 329 collection of 328 constituents of 332 crude 317, 320-32^ definitions 330 desiccation 331, 332 fibrous 334 grades 321 identification 320 inorganic 317 organic 317 preservation of 328, 332 tissues of 334 varieties 321 Drum seives 436 Dry distillation 429 Drv processes 130, 131 Dry way 130, 11 Ductilitv 7, 163 Dulong and Petit, law of 143, 144 Duo 292 Dyads 152, 153 Dynamic electricity 102, 105 Dynamics 13, 47 Ebullition 94, 451 5 12 INDEX. Edges of crystals 18 Efflorescence 15, 26 Elasopten 341 Elasticity 7, 16 Elder flowers 363 Electric batteries 105 cells 105 circuit 105 currents 105 phenomena 104 plates 105 polarity 103, 105, 134, 136 Electricity 13, 102, 129 conductors of 104 dynamic 102, i05 frictional 10. galvanic 102, 134 negative 103, 134 positive 103, 134 static 102 voltaic 102, 134 Electricity, relation to chemistry 125, 133, 134, 2i4 Electro-chemical polarity 125, 135, 214 series 136-138 theory 135 Electrodes 105 Electrolysis 106, 134, 135 Electrolytes 106, 134 Electro-negative radicals 135 Electro-plating 106 Electro-positive radicals 135 Electro-typing 106 Electuaries 478 Elements 112, 113, 14 electro-negative 136 electro-positive ]38 metallic 16 <, 211-213 non-metallic 163, 164, 195 chemical behavior 168, 169 occurrence in nature 166 physical properties 164-169 polyvalent 138 proportions of, in compounds 139-143 review of 163 symbols of 162 table of 112-113 Elutriation 434 Emetics 395 Emetine 349 Emmenagogues 395 Emodin 351, 357 Emollients 397 Empirical formulas 2S0 Emplastra492 Emulsification 482,483 Emulsifying agents 482, 483 Emulsion 338, 358, 482 Emulsion mortar 432 of turpentine, 433 Emulsions 482, 483 Endings 496-503 Enemata 494 Energy i3 chemical 113, 123-125 conservation of, 14 correlation of, 14 electrical 102 kiaetic 74 of motion 53, 74 Energy of position 53, 74 potential 74 radiant 85 Ennea 292 Epsom salt 203 Equations, chemical 161, 162 Equilibrium 50 Equivalence 151 Equivalent radicals 153 Ergot 374 Ericolin 367 Erythroxylon 364 Escharotics 397 Eserine 373 Essential oils 340 Esthers 285 Ether as a solvent 442 Etherial oils 340 salts 285 Ethers 284, 286 compound 285 simple 284 Ethyl 217 Eucalyptus 365 Eupatorium 360 Evaporating dishes 452 Evaporation 93, 95, 451, 452, 453 cold from 95 rate of 93 spontaneous 93 Excess of one factor in 310 Excipients 479 Expansibility 7 Expansion, co-efficients of 87 cubical 87 force of 87 linear 87 in solidification 91 of bodies by heat 86 of water 88, 89 unequal 88 Expectorants 396 Exsiccation 428 Extract 467, 488 Extraction 467 forces concerned in, 470 methods 468 Extractive 467, 468 Extracts 488 Fats 333, 338, 339, 385 animal 339 Fatty series 279 Faces of crystals 18 Factors of reactions 125, 126, 305, 310 Fahrenheit's thermometer 78 Fel bovis 391 Fennel 370 Fermentation 122, 337, 450 Ferric compounds 206 iron 205 Ferrous compounds 206 iron 205 Fibrous drugs 334 Filter baskets 447 funnels. 445 446 paper 444 stands 446 INDEX. 513 Filters 443-445 plain 144 paired 445 Fi trate 443 Filtration 443-447 Fineness of powders 436 Fire 129 Fixed alkalies 91. 131 substances 18, 91 oils c 33, 3o8, 339, 385 Flasr. blue 349 Flasks 454. 4^9 F. ax seed 372 oil 385 Flowers 331. 332 of sulphur 177 Fluids j 7 Fluid-extracts 487 Fluorescence 101 Foeniculum 370 Fog 98 Foot-pound 54 Force 8 centrifugal 49 chemical 113, 153, 124 constant 52 electric 102 of expansion and contraction 87 repellant 12^ attractive 8-12 Forces 8 Formic acid 282 Formulas, chemical 159, 160, 219, 230,231, 276, 27^. 285 constitutional 231 empirical 230 for acids 219 general 276, 277, 278. 285 molecular 159, 160, 230 rational 231 structural 231 symbolic 159, 160 Foxglove 364 Fractional distillation 454, 457 Frangula 357 Frangulin 357 Franklinism 102 Freezing by evaporation 96 mixtures 92 points 9('. 91 solutions to concentrate them, 46 Friction 58 Frictional electricity 102 Frost 98 Fruit acids 340 Fruit flavors, artificial 285 Fruits 332 Fuel! 73, 422,423 Fulcrum o5 Funnels 445, 446. 447 Fusel oil 281 Fusibility of elements 164 Fusing points 75, 90 Fusion 90, 428 aqueous 129 igneous 129 Calbanum 380 Galen 319 Galenical preparations 319 Galena 19, 206 Galla 359 Gallic acid 359 Galvani 133. 134 Galvanic electricity 102, 134 Gamboge 380 Gargles 494 Garlic 345 Gas burners 424, 455 liquor 2U0 Gases 17, 6ti, 87. 90, 96 atoms of in equal volumes 145 expansion of 87 generation and solution of 458 tension of 66 Gelsemine 348 Gelsemium bi~ Genitives. Latin 496-5C0 Gentian 348 •'Gentle heat" 457 Ginger 354 Glass 194, 270 Glass tuhinff. cutting of 459 Glauber's salt 199 Glucose 288, 335. 337, 379 Glucosides *88, i95. 343 Glycerin 28-. 338, 442 bath 427 Glvcerites48i Glyceryl 217, r38 saits 338, • 39 Glycogelatin 494 Glycvrrhiza348 Glycyrrhizin 34S Gold 210 Golden seal 348 Gossypii radicis cortex 357 Guaiac resin SSL wood 354 Guarana 375 Guaranine 376 Gum arabic 335. 378 properties of 335 Gums 333, 335, 3: 6 Gum-resins 342. £43 emulsions of 4^2 Gun-cotton 404 Gram 501. 505, 0C6 Granatum 357 Granulation 464 Granules 478. 479 Grape sugar L37 Graphite 191 Grating of drugs 431 Gravity 9 Gravitation 9 Grindelia 360 Grinding drugs 431 Ha?matoxvlon 355 Hail 98 Halogens 179. 240 Haloids 176, 240-252, 253, 258 Hardness 7 Hartshorn salt 200 Hellebore, American 354 Hemlock 369 Hepta 292 Heptads 152, 153 Herbs 331 5i4 INDEX. Hesperidin 355 Heterogeneous bodies 36, 11^, 116, 120 Heteromorphous bodies 20 Hexa 292 Hexads 152, 153 Hexatomic molecules 148, 224 Heat 13, 73, 74, 75 absolute 80 absorption 86 active 74 action of upon salts 129 amount from fuel 422 and chemism 128, 129 a repellant force 128 atomic 144 conduction 82, 83 conductors 83 control of 425 convection 82-84 distribution 82, 425 effects of 421 expansion 86 intensity 101, 422 in pharmacy 421 latent 74, 92, 95, 96 of vapors 95 molecular 145 non-conductors of 83 radiant 85. 98 radiation 82, 84, 8j reflection 85 refraction 85 sensible 74 softening by. 91 sources of, 76 specific 80, 81, 82 theories of, 73, 75, 85 transmission of, 85, 86 unduiatory theory of 85 units 81 waves 85 Heating apparatus 423 Hippocrates' sleeve 448 Hoarhound c61 Homogeneous masses 37, 110, 115 Homologous series 234, 277, 278 Honey, 337, 379 Honeys 481 Hops 370 Horse-pQwer 54 Hot- water coil 424 Humulus 370 Hydracids ;53 H ydragogue cathartics 396 Hydrastine 348 Hydrastis 348 Hydrates 2 12, 215, 248, 249 Hydraulic press 60 Hydriodic acid 182 Hydrobromic acid 182 Hydrocarbons 276-280 of methane series 286 nomenclature of 295 Hydrocarbon radicals 279, 180 Hydrochloric acid 140, 181,254 Hydrocyanic acid 185 Hydrodynamics 58 Hydrogen 173 acids 176. 253 alloys 175 Hydrogen arsenide 189 as a reducing agent 173 bromide 182 chloride 18L nascent 130 negative 176 peroxide 174, 215 polarity of 138, 175 positive 176 radicals 176 replaceable 175, 176, 219 Hydrogen solidified, 175 sulphide 179 valence 151 variable polarity 175 Hydromel 481 Hydrometers 63-66 Hydrostatic balance 55, 63 paradox 59 press 60 Hydrosulphuric acid 178 Hydrous crystals 26 Hydroxides 215, 247-2j;0 Hydroxyl 138, 174, 175, 215-217, 247, 282 acids 172, 2:51, 252 table 25 i Hygroscopic bodies 15 Hyoscine 365 Hyoscyamine346, 363, 365, 366, 373 Hyoscvamus 365 Hyper- 294 Hypnotics 395 Hypo- 294 Hypochlorites 181, 262 Hypophosphites267, 268 Hyposulphites 264 Iceland spar 19 "ic" 292-295 Identification of drugs 320 Igneous fusion 129 Ignition 428 Impenetrability 2, 6 Imperial weights and measures £04, CC5 Incandescence 99 Incineration 428 Inclined plane 57 Incompatibilities 299 Indeclinable nouns 498 Indestructibility 6, 118, 119 Indian cannabis 360 hemp 360 tobacco 360 Induction 103 Inertia 7, 48 Infusion 469, 470 Infusions 484 Ingredients 36 Injections 494 Inorganic chemistry 168 compounds 234 drugs 317 substances 109 Insoluble compounds 29S, 299, 307, 3CS, 44i Insulators 104 Iodides 244, 245, 246 Iodine 182 Iodoform 279 Ipecac 349 Iris versicolor 349 INDEX. 5*5 Irish moss 374 Iron 205, 206 group 204 Irritants 397 Isomorphous bodies 20 J aborandi 365 Jalap 349 Jasmine, yellow 347 Javelle water 262 Jervine 354 Jimpson weed 366 Juniper 370 Kamala 370 Kermes mineral 238 Ketones 282 Kilogram 502, , r 03. 504 Kilogram meter 54 Kilometer 504 Kinetic energy 53 Kino 376 Koosso 361 Krameria 349 Labarraque's solution 181, 263 Laboratory thermometers 79 Lactates 272 Lactic acid 283 Lactucarium 376 Lamp stand 446 Lard 385 Lard oil 385 Latent heat 92, 95, 96 Latin declensions 495-502 names 495, 496 Laughing gas 183 Lavender 362 Law of Archimedes 61-66 Avogadro 146, 147 Boyle 87 Charles 67, 80, 87 combining proportions 140-143 Dalton 140-14'% Dulong and Petit 143, 144 gravitation 9 Mariotte 66, 87 opposites in chemistry 131-136 Laws of motion 48 Laxatives 396 Lead and compounds 206, 207 plaster 493 Leaves 331, 332 Leptandra3 Levers 55, 56 I.evigation 434 Licorice root 348 Liehig's c ndenser 455 Light, 13, 98 absorption of, 100 chemical effects of, 101 rays of, 101 effects of, upon drugs, 101, 102 heat rays of, 101 luminous, rays of, 101 radiation of, 99 ravs 99, 100, 101 reflected 100 refraction of, 100 sources of, 99 Light, white. 99 Liguin 333, 334 Lime 20 L water 201, 248 Line of direction 50 Linear expansion 87 Liniments 494 Linkage 229 Linseed Oil 385 Linum 372 Liquids 16, 90 decantation of 39 diffusion of 41, 471 form of 21 miscible 36, 4R, 47 pressure of 58, 59 viscous 447 volatile 92. 93 Liquores 441, 480 Liquorice root 348 Liter 1 03, 504. £05 Lithium 199 Litmus paper 303 Liver of sulphur 238 Lobelia 360 Lode stone 102, 103 Logwood 355 Lotions 494 Lozenges 478 Luminous bodies 99 rays 99 Lupuiin 370 Lustre of elements 165 Macera+ion 468, 473 Machine o5 Magdeburg spheres 73 Magma 312 Magnesia 203 Magnesium and compounds 203 Magistral formulas 324 Magnetic substances 103 Magnetism 102 Magnets 102, 103 Malaguti's law %96-298 Male fern 346 Malic acid 284 Malleability 7, 166 Mandrake 350 Manganese chlorides 141 dioxide 171 oxides 140, 142 Manna 337, 379 Man nit 379 Maple sugar 336 Maranta 378 Marble 201 Marc 475 Mariotte's law 66 Marrubium 361 Marsh gas 276, 279 Marshmallow 3i6 Mastic 382 Mass 2, 6 attraction 8-12 motion 13 Masses 114, 478 heterogeneous 10 homogeneous 110 molecules and atoms L16, 117 5i6 INDEX. Massing 479 mortars 433 Materia medica 319 pharmaceutica 320 Matico 365 Matricaria 363 Matter 2 atomic 6 divisibility of 141, 142 frozen 90 kiods of 5, 115 melted 90 molar 6 molecular 6 properties 4-8 states of aggregation of 14 vaporized 9U Maximum density of water 8?, 89 solubility 438 Measures 503-505 Mechanical science 13 Medicines 317 systemic 392 topical 392 Mel 379 Mellita 481 Melting points 75, 90 Mendeleef 's periodic law 169, 170, 210 table 170 Menstrua 442 Mentha piperita 361 Menthol 389, 391 Mercaptans 282 Mercur-ammonium 217 Mercurial thermometer 77 Mercuric mercury 207 Mercurous mercury 207 Mercury and compounds 207, 208, 209 "Meta"294 Metallic compounds 213 Metals 163 action of acids on, 254, 255 alkali 196, 197 alkaline earth 200 chemical behavior of, 168 heavy 196, 204 light 196 noble 210 polarity 136 relative power as positive radicals 136, 138 review of, summary 211-213 Metaphosphates 267 Meter 503, 504 Methane *76, 279 Methene 217 Methenyl 217 Methyl 217 salicylate 388 Metric system 503 units, equivalents of 504 Mezereum 357 Microcrystalline bodies 21 Milk sugar 337 379 Milligram 503,504 Mineral kingdom, 109 substances 109 tonics 393 Miscibility 36, 46, 47 Mitscberlisch's condenser 456 definition of isomorphism Mixed substances 36, 37, 1 10, 1.6 Mixtures 36, 37, 111), 116, 482 Mixture mortars 433, 431 Mobile liquids 16 Molar attraction 8, 12 force 13 matter 6 motion 13 Momentum 49 Mon-acid bases 249 Monads 152, 153 Monatomic molecules 224 " Mono-" 292 Monobasic acids 251 Morphine 376, 377 Morphology 323 Mortar, iron 431 Mortars 431-434 Moschus 392 Mother liquor 309. 464 Motion 13, 47 laws of 48 Motor depressants 394 excitants 394 Molecular attra- tion 8, 12 formulas 159, 160, 230, 233 heat 145 matter 6 motion 13 weight 145-148 Molecules 5, 6, 114, 116, 117 atomicity of 147, 2-4 complex 157 compound 114, 224, 2^6 diameter of 142 diatomic 147 elemental 114 formation of 225, 2^6 hexatomic 148 number of in volumes cf gases 147 atoms in 147 sta.bl6 129 stability of, relative, 123, 129, 131, 136 tetratomic 147 triatomic 147 unstable 129 Mucilages 333, 335, 336, 481 Mucilaginous drugs 3.5 " Multi -" 294 Multiple proportions 140-143 Muriate of ammonia 200 Muriatic acid 181, 132, 133 Musk 392 Mustard 373 Mydriatic anodynes 394 Myristica 372 Myrrh 381 Names of compounds 289-295 Nascent state 130 Natural gas *79 Negative pole 134 radicals 135, 136, 215, 217, 222, 223 Neumann's investigations 1 44 Neutral principles 288, 295, 3_3, 343 Neutralization 132, 303 Nicholson's hydrometer 61 Nicotine 367 INDEX 517 Nitrates 213, 259-261 Nitre 260 Nitric acid 133, 183, 185, 254, 301 anhydride 235 radical 259 Nitrogen 183 group 182, 186 compounds of 187, 195 indifferent energy 184 negative 154 oxides 141, 183, 184 poly valence of 184 positive 154 radicals 184 valence of 154 Nitrosyl 217 Nitrum 132 Nitryl 217 Nomenclature 289, 295, 324, 495 chemical 289, 295 Latinic 495 Nona 292 Numerals, use of, 159, 292, 500 Nutgall 359 Nutmeg 372 Nux vomica 372 Oak bark 358 Octo 292 Octohedron 29 Official 324 Officinal 324 Officine 324 Oil bath 4*7 castor 339 croton 339 emulsions 483 of allspice 389 almond 385 anise 387 bergamot 387 bitter almond 387 caraway 387 cinnamon 388 cloves 388 copaiba 388 coriander 388 cubeb 388 eucalyptus 388 fennel 388 juniper 389 lavendeo- 389 flowers 389 lemon 389 mustard, volatile 390 neroli 387 orange flowers 387 orange peel 387 peppermint 389 pimenta 390 rose 390 rosemary 390 sassafras 390 savin 390 star anise 387 theobroma 386, 493 turpentine 390 vitriol 132, 133 wintergreen 388 Oil, olive 338, 386 Oils, drying 339 esseutial &33, 340, 341, 387 ethereal 340, 387 fixed 333, 338, 339, 385 non-drying 339 volatile 333, 340, 341, 387 Ointments 491 Oldberg's percolator 471 uleates, 272, 338, 493 Oleoresins 342, 490 Oleum adipis 385 amygd. amar. 387 express. 385 anisi 387 aurantii cort. 387 flor. 387 bergamii 387 cari 387 caryophylli 388 cinnamomi 388 copaibas 388 coriandri 388 cubebas 388 eucalypti 388 fceniculi388 gaultheriae 388 gossypii 385 juniperi 389 lavand. 389 flor. 38 limonis 389 lini 385 mentha? pip. 389 morrhuae 386 olivge 386 pimenta? 389 ricmi386 rosse 389 rosmarini 390 sabinae 390 sa saf ras 390 sesami 386 sinapis vol. 390 terebinth. 390 tiglii 386 theobromae 386, 493 Oleic acid 339 Olein 338 Olive oil 338, 386 Opacity of elements 165 Opaque bodies 99, 165 Opium 376 Opposites in chemistry 131-136 Orange peel 355 Ordinals 501, 502 Organic acids 282-284, 333, 340 bodies, forms of 21 chemistry 192 compounds 235 drugs 317, 320-322 oxides 284 substances 109 Organized matter 21 Organography 323 "Ortho— " 294 Orthometric forms of crystals 28 Orthophosphates 265—266 Orthosulphuric acid 275 Osmose 42, 470 Otto 340 5i« INDEX. "-ous' 1 29?-295 Ox-gall 391 Oxalates 273 Oxalic acid 283 Oxidation 171. 259, 3 1, 302, 428 Oxides 133. 172, 212, 235-237 table of 236-237 acid-forming 138, 235 basic 138, 235 higher and lower 293 indifferent 235 neutral 235 nomenclature of 291-293 organic 284 of chlorine 141, 180 hydrocarbon radicals 284 manganese 140 nitrogeDl41,183, 184 sulphur 178 Oxidizing agents 259, 3C2 Oxygen 171, 2il compounds 177 electro- chemical polarity of 138 radicals 173 Oxy-chlorides 240 Oxv-hydrogen burner 173 Oxy-oleic acid 339 Oxv-salts 172,215.258 Oxy-sulpburet of antimony 2, 33 Oxymel 481 Oxytocics 395 Ozone 172 Palmitin 339 Palmitic acid S39 Paper filters 444 Papers, medicated 491 Papin's digester 94 Para- 294 Paraffin 279 Paregoric 377 Pareira 350 Pearl ssh 199 Pectin 333, 336 Pelletierin 3 7 Pendulum 52, 53 Penta- 292 Pentads 152, 153 Pentatomic molecules 224 Pepper, African 367 black 371 Cayenne 367 red 367 Peppermint 361 Pepsin 392 Per- 294 Percolate 471, 474 weak 474 Percolation 471-475 simple 474 Percolators 471, 472 Periodic function of atomic weights law 169 Perissads 152 Permanganate 270 Peruvian bark 356 Peroxide of hydrogen 174 Pharmaca praeparanda 320 simplicia 320 Pharmaceutical chemistry 318 preparations 319 Pharmaco-dynamics 326 . Pharmacognosy 320 Pharmacology 320 Pharmacopoeia 324, 325 Pharmdco-technologv 326 Pharmacy 325, 326, 4=h Phenolsulphonates 275 Phenomena 8 chemical 118-123 Phenyl 217 Phosphates 212, 265, 266 Phosphine 188 Phosphorescence 99 Phosphorus 186, 187 acids of, 188 compounds 187, 188 negative 154 oxides 187 positive 154 red 187 valence 154 Phosphoric acid 1S8 anhydride 235 Physical properties of matter 117, 120 science 1)8 Phvsics 117. 118 Physiology 327, 328 Physostigma 372 Phytolacca 350 Pill mortars 433 Pills 4T8, 479 Pilocarpine 365 Pilocarpus 365 Pinkroot 353 Piper 371 Piperine 371 Pipettes 69 Pix burgundica 382 liquida 384 Plant constituents 332 drugs 328 Plaster of paris 2^1 Plasters 272, 339, 492 Platinum group 210 Pneumatic inkstand 69 Pneumatics 58, 66 Podophyllin 351 Podophyllum 350 Poisons 3.8 Poke root 350 Polar force 103 Polarity and valence, 154, 155 electro-chemical 125, 135, 154, 155, 214 relation of to atomic weight 13i valence 138 Poles of the magnet 103 opposite 103 Poly- 294 Polyatomic molecules 224 Polygalic acid 352 Polymorphous bodies 20 Polyvalent elements 138, 182, 186, 192, 193 nerissads 182, 186 radicals 15 J Pomegranate root bark 357 Porosity 6 Positive pole 134 radicals 135, 215, 217, 220-222 INDEX. 519 Posology 327 Potential energy 53 Potassium and compounds 198, 199 position of in electro-chemical se- ries 138 Potassa 248 Poultices 491 Powder mixing 433 mortars 432 Powders 43ft, 436, 437, 477 Precipitate 306 Precipitates 311 drying 313 properties 466 washing 311, 312 Precipitating vessels 308, 466 Precipitation 46, 298, 299, 306, 307, 465, 466 chemical 307 physical 46, 307 Precipitand 308 Precipitant 308 Predisposing affinity 131, 183 Prefixes in nomenclature 290-294 Preparations 3i9, 476, 477 class fication 476, 477 extemporaneous 324 galenical 219 Press, Brahmas 60 hydraulic 60 hydrostatic 60 Pressure, relation of to boiling points 94 Primary colors 100 Principles, active 333 inert 333 neutral 333, 343 proximate 332 Prism, rhombic 33 Prismatic colors 100 Prisms 24, 30-34 hexagonal, 30 monoclinic33 quadratic 32 six-sided, 30 tn-clinic30 Processes, dry, 130, 131 wet. 130, 131 Products of reactions 309, 125, 126 principal 309 secondary 309 Properties chemical 118 physical 170, J 20 Propo' tions combining 139-143 multiple 140-1 3 of factors in reactions 309, 310 volume 145, 148 Protiodide of mercury 245 Proto 294 Proximate principles of drugs 332 Prunin 358 Prunus virginiana 358 Prussian blue 26, 246 Prussic acid 185, 246 Pulley 57 Purgatives 396 Putrefaction IJ38 Pyramid, hexagonal 30 monoclinic 33 rhombic 33 square-based 32 triclinic 34 Pyramids 24, 30, 32, 33, 34, 35 Pyrites 177 Pyro .94 Pyroarsenates 270 Pyrocatechin 384 Pyroleum 384 Pyromerers 79 Pyrophosphates 2 Pyroxylin 494 Quadri 294 Quadrivalent radicals 152, 153 Quantity of chemism 150 Quativalence 151 Quartz cr} stal 30 Quassia 355 Quaternary compounds 234 Quebracho 355 Queen's root 353 Quercitaunic acid 358 Quercus alba 358 Quince seed 372 Quinidine356 Q -inine356 Quinque 292 Quinquivalent radicals 152, 153 Radiation of light 99 Radicals 124, 125 acid 251, 253 acid -forming 216, 253 acidulous 222, 223 basylous 220, 221,223 compound 124, 125, 213, 214, 215 elemental 124, 125 how united 226 hydrocarbon 286 negative 135, 215, 217, 22?, 223 nomenclature of 215 of the methyl series 283 organic 285 positive 135, 136, 176, 215, 217, 220, 221, 21 12 relative energy of 296 salt 256 simple, 124, 125 tables of 220-223 valence of 151, 220-223 Rain 70 Kancidity 339 Rasping of drugs 431 Rational formulas 231 Rays of light 99 Reaction on test paper 303-305 Reactions, 119-123, 12,-131, 225, 253, 255, 296-300,305,3,6,309, 310 analytical, 126 between dry substances 127, 128 gases 127 liquids, 128 direction and completeness of 296- 300 factors of 125, 1 6 proportions of 309, 310 laws governing, 296-300 of acids and bases 253 with metals, oxides, etc. 255 on litmus paper 303-305 products of 125, 126 5 Reactions, synthetical 126 Reagents 126 Reaumour's thermometer 78 Receivers 96, 456 Red pepper 203 Red precipitate 367 Reducing asrents 173, 264, 302 Reduction 302. 428 Reflection of heat 85 light 100 Refractory bodies 90 Ret -angibilirv of beat rays 85 light i00. 10 L Regnault's investigations 144 Re-maceration 468 Repeilant force 81, i:8 Repercolation 474 Replacement 333 Repulsion 8 Residue 219, 249, 251 acid 251 base 249 Resin s aps 343 Resina 381 Resinification 341 Resins 333, 341,342 acrid 342^ balsamic 342 hard 342 precipitated 490 soft 342 Resistance 51 Retorts 454 " Retort stands " 446 Rhamnus purshiana 358 Rhatany 349 Rheum 351 Rhizomes 331 Rhombohedron 31 Rhubarb 351 Rings 229 Roasting 428 Rochelle salt 199 Rock candy 337 crystal 19 Roman numerals 500 Roots 331 Rose 362 Rosemary 366 Rosmarinus 366 Rottlerin 370 Rubefacients 397 Rubus 359 Rust 122 Saccharose 288, 336, 378 group 288 Saccharum 378 lactis379 Saffron 362 Sa*e3d6 Sal ammoniac 200 soda? 199 volatile 200 Salicylates 275 Saline cathartics 396 Salt 240 Salt formers 172, 179. 180 of tartar 199 radicals 256 INDEX. Saltpetre 199. 260 Salts 172, 256-258 acid 256 action upon, by heat 129 alkaloidal 289 basic 257 classes of 256, 257 double 25^ nomenclature 291, 295 normal 256 of alkaloids 289 reactions of, on litmus paper 303- 305 Salvia 366 Sambucus 363 Sand bath 42b Sanguinaria 351 Santonica 363 Santonin 363 Saponin 352 Sarsaparilla 351 Sassafras 359 Saturating power of atoms 150 Saturation 132, 305 Scale salts 206 Scalenohedron 31 Scammony 382 Scilla 352 Sclererythrin 374 Scleromucin 374 Sclerotic acid 374 Screw 57 Secale cornutum 274 Seconds pendulum 53 Sedatives 395 Sediment 450, 465 Seed emulsions 482 Seeds 332 Selenium 178 Semi-fluids 16 Semi-sol ; ds 16 Senega 352 Seneka— «nakeroot 352 Senna 366 Septivalent radicals 152. 153 Sexivalent radicals 152, 153 Serpen taria 352 Sesamum oil 386 Sesqui- 294 Sevum 3^5 Sexi- 292 Sieves 43 \ 436 Silicates 269, 270 Silicon 194 Silver and compounds 219 Simple solvents 440, 441 Sinapis 373 Siphons 70, 71,449 Skeletons 228 Slicing drugs 430 Slippery elm bark 359 Snake-root 347, 352 Snow 98 Soaps 272. 338, 339, 342 resin 342 Soda 199, 248 Sodium and compounds 199 Solar spectrum 100 Solids 14, 15, 90 form of 15 INDEX. 521 Solubility 44, 440-442 maximum 438 of elements 166 Solution 44, 437-443 baths 94, 427 chemical 45, 439 compound 45, 439 fractional 440 of gases 440, 460 liquids 440 soJids 437 partial 439 saturated 45, 439 simple 45 super-saturated 439 Solutions 441, 480 boiliDg points of 94, 427 concentrated by freezing 46 of gases 460 SolveDts, 44, 46, 440, 441, 442 chemical 46 neutral 46 simple 40 pharmaceutical 440-442 Sorghum sugar 336 Sound 13 Spanish flies 391 Spatula 434 Species 430, 477 Specific gravity 10, 12, 146 heat 143, 144 weiarht 10, 1-', 146 Spectrum 100 Spermaceti 385 Spices 342 Spigelia353 Spiral condensers 456 Spirit lamp 424, 4i5 of hartshorn 200 Spirits 484 Spritz bottles 71 Squill 352 Stability 51 Stable molecules 129 Stands 446 Starch 333, 334, 378 States of aggregation 14, 17, Statistical electricity 1U2 Status nascens 130, 183 Steam 95, 424 Stearic acid 339 Stearin 339 Stearopten 341 Sticking plaster 492 Stillintna 353 Stills 96, 453 Stimulants 395 Stinkweed 366 Storax 383 Straining 447 Stramonium 366 seed 373 Stress 48 Strontium and compounds 202 Structural formulas 231 Strychnine 372 Styracin 383 Styrax 383 Styrol 383 Sub 294 Sublimation 90, 97, 429 Subsidence 448 Substances 5 mixed 110 Substitution 135, 225, 233, 234 products 234 Succinic acid 284 Sucrose 336 Sudorifics 396 Suet 385 Sugar 378 beet 336 grape 337 maple 336 milk 379 names of, 293 sorghum 336 white 336 Sugars, 333, 336-338 Sulphates 212, 262-264 Sulphides 212, 238, 239 Sulphites 2-54, 265 Sulphocarbolates 275 Sulpho-cyanogen 217 Sulphur 138, 176 compounds 177 dioxide 178 negative 154, 177 oxides 178 positive 154 trioxide 178- valence of 154, 177, 178 Sulphurated antimony 238 lime £38 potassa 238 Sulphuretted hydrogen 178 Sulphuric acid 138, 178, 254, 262 anhydride 178, 235 Sulphurous acid 178 anhydride 178 Sulphuryl 218 Sulphydric acid 178 Super 294 Supernatant liquid 448 Suppositories 493 Symbolic formulas l',9, 160 Symbols 112, 113, 158, 162 Synaptase 338 Synthesis 126 Systemic medicines 393 Syrups 336, 481 Sweet flag 346 Tabacum 367 Tablets 478 Tannic acid 344, 359 Tannin 344, 359 Tar 384 Taraxacum 353 Tartar 198, 273 emetic 274 Tartaric acid 283 Tartrates 2W, 274 Technical terminology 495, 496 terms 323 Technology 326 Tellurium 178 Temperature 75, 77 absolute 80 effects of 427 equalization of 82, 91 5 22 INDEX. Temperature of vapors 93 Tenacity 7, 160 Tension 17, £6, 89 Tenaculum 448 Ter- 292 Terebmthina 384 canadensis 384 Terminology 323, 495, 4 96 Ternary compounds 23' Terpenes 341 Test papers 303 Tetra 292 Tetra ba^ic acids 251 Tetrads 152, 153 Tetratomic molecules 147, 224 Theine 376 Therapeutic classification of medicines 392 Therapeutics 3?7 Thermal rays 85 units 81 Thermometer, Celsius' 77 centigrade 77 Fahrenheit's 78 Reaumour's 78 Thermometers 77—79 air 79 laboratory 79 spirit 79 Thermometric degrees 78 scales 78 Thermometry 77 Thiosulphates 264 Thistle tube 41, 455 Tin and compounds 194 Tincture of iron 206 Tinctures 486, 487 Titles 496 Tobacco 367 Indian 3H0 Tolu 383 Tonics 393 Topical medicines 392 Torrefaction 428 Torricellian vacuum 72 Toxicology 328 Tragacanth 335, 378 Translucent bodies 99 Transparent bodies 99 Tri- 292 Triads 152, 153 Triatomic molecules 147, 224 Tri basic acids 251 Trimorphous bodies 20 Trituration 433 Triturations 477 Trivalent radicals 152, 153 Troches 478 Turpenes 341 Turpentine 384 Canada 384 emulsion 483 Tvpe theory 231, 232 Types, chemical 232 Ulmus359 Cni- 292 Units of heat work 54 Univalent radicals 152, lo3 Unstable molecules 129 Ursone 3b7 Uterine sedatives 395 Uva Crsi 367 J, 95 Vacuum 3, 71, 7 pans 7 A 453 Valence 12\ 150-158, 233 and polarity 154, 155 the formation of molecules 226, 2 7 how indicated 161 maximum 155, 156 of chlorine 180 nitrogen 154 phosphorus 154 sulphur 177, 178 radicals 2.'0-223 reduction of 155, 156 relation of to polarity 138 ruling 156 true J 55 variable 154-158, 290 Valentine 3i9 Valerates 271 V alerian 353 Valeric acid 353 Vanilla 371 Vanillin 371 Vapor 17, 97 density 146 Vapors 96 latent heat of 95,96 specific weight of 146 tension of 66 Vaporizable solids 90, 91 Vaporization 94, 45 L Variable valence 154-lc8 Varnishes 342 Vegetable kingdom 109 Velocity 49 accelerated 52 of falling bodies 51, 52 Ventilation 84 Veratrum yiride 354 Vesicants r97 Vinegars 486 Viscid liquids 16 Viscous bodies 16, 35 liquids 16, 35, 447 Vitriol, blue 208 green J.06 Volta 133. 134 Voltaic electricity 102, 134 Volatile bodies 18, 90, 92, 93, 164 elements 164 liquids, 92, 93 oils 333, 340, 341, 387 products of reactions 300 solids 90 substances 18 Volatilization without fusion £0 Volume 2 combination by 145, 148 expansion of, by heat £6 Volume proportions in chemical com- bination 145 Volume relation of to weierht 10-12, 88„ 89, 503, 504, 505 INDEX. 523 Warmth 73 Wash bottles 71, 458, 459 water 312 Washing of precipitates 311, 312 Washings 312 Water 13», 139, 140, 171, 173, 174 as a solvent 440 bath 426 boiling point of 89, 84 expansion of 88, 89 density of 88. 89 interstitial, of crystals 25 maximum density of, 88, 89 of ammonia 200 crystallization 15, 20, 26-28 specific weight of, 88, 89 vapor 95 volume of, 88, 89, 503, 504, 504 one grain of, 12 weight of, 88, 89, 503, 504, 505 Water-gas 173 Water-glass 270 Water-soluble substances 440 Waters 480 Waves of heat and light 85, 98 Wax 385 Weather and health 98 Wedge 57 Weighty 10, 61,62 absolute 10, 61, 62 apparent 10, 61, 62 Weight, molecular 145-148 specific 10-12 true 10, 61, 62 relation to volume 503, 504, 506 Weights and measures 503-505 apothecaries' 504 British 504, 505 metric 503 Imperial 505 Wet processes 130, 131 way j 30, 131 White light 100 precipitate 209, 241 Wild cherry bark 357 Wind 81 Wines 487 Wood spirit 281 Woods 331 Woody fibre 3 '4 Work, rate of, 54 Worm 455 Wormseed American 368 german 363 levantic 363 Woulf 's bottles 458 Yellow jasmine 347 Zero absolute 80 thermometric 78 Zinc and compounds 204 group 202 Zinziber 354 xm^*M ^* ill : 4^ •# ^ #»'■.:>/; ■ LIBRARY OF CONGRESS ODOEbbSbbEA ■i 1 mm