MEDICAL CHEMISTRY. PROF. E. H. BARTLEY. JUST PUBLISHED. Yeo’s Manual of Physiology. A Manual of Physiology for Students and Physicians. By GERALD F. YEO, M.D., F.R.C.S., Professor of Physiology in King's College, London. WITH OVER 300 CAREFULLY PRINTED ILLUSTRATIONS AND A GLOSSARY. SMALL OCTAVO. 750 PAGES. CLOTH, $4.00; LEATHER, $5.00. “ The work will take a high rank among the smaller text-books of Physi- ology.”—Pro/. H. P. Bowditch, Harvard Medical School. “ The brief examination I have given it was so favorable that I placed it in the list of text-books recommended in the circular of the University Medical College.”—Prof. Lewis A. Stimpson, M.D., 37 East 37th street, New York. “ After a careful examination of this manual of Physiology, I can truth- fully say that it is a most valuable addition to the list of text-books upon this subject. That it should and will receive a welcome from both students and teachers there can be no doubt; for, in addition to the familiar but well presented facts of most text-books, it contains all the more important facts of physiological science which have been established in the last few years. The author presents his subject in a manner that is clear, concise and logical. Each section has had a careful revision, and reveals the author’s familiarity with the scope and tendencies of modern physiology.”—*A. P. Brubaker, M.D., Demonstrator of Physiology in Jefferson. Medical College, Phila- delphia. P. BLAK1STON, SON & CO., Philadelphia. Absorption Spectra. EXPLANATION. Solar Spectrum. Ammonio-copper Sulphate. Prussian Blue (in oxalic acid.) Indigo (in sulphuric acid.) Potassium permanganate (in water.) Aniline red (fuchsine.) Chlorophyll (in ether.) j Tincture of Aconite leaves Carmine (in ammonia.) Oxy h aemoglobin (art. blood.) Reduced Haemoglobin. Oxyhaematin. Reduced haematin. Methaemoglobin. Blood 4- N a S in excess. Urobilin (in acid sol.) Urobilin (in alkaline sol.) A TEXT-BOOK OF MEDICAL CHEMISTRY. FOR MEDICAL AND PHARMACEUTICAL STUDENTS AND PRACTITIONERS. BY ELIAS H. BARTLEY, M.D., ADJUNCT professor of chemistry, and lecturer on diseases of children in long island COLLEGE HOSPITAL; CHIEF CHEMIST TO THE DEPARTMENT OF HEALTH, CITY OF BROOK- LYN, N. Y.; CHEMIST TO THE NEW YORK STATE DAIRY COMMISSION ; INSPECTOR NEW YORK STATE BOARD OF HEALTH; PRESIDENT OF THE AMERICAN SOCIETY OF PUBLIC ANALYSTS; MEMBER OF THE AMERICAN CHEMICAL SOCIETY; MEMBER OF THE AMERICAN SO- CIETY FOR ADVANCEMENT OF SCIENCE. WITH FORTY ILLUSTRATIONS PHILADELPHIA: P. BLAKISTON, SON & CO., 1012 Walnut Street. 1885. Copyright, 1885, by P. BLAKISTON, SON & CO PREFACE. This book is designed especially as a text-book for medical students during their attendance upon lectures. It is believed, however, that it will be found of use to the physician, as a book of ready reference. It is the result of the author’s experience as a teacher of Chemistry, during the past twelve years, and its plan, and much of the subject matter, are essentially that given by him in his lectures at the Long Island College Hospital, for the last six years. While there are numerous good text-books on Chemistry in the market, the medical student often complains that they are either too voluminous for his limited time, and contain a great deal of matter not directly bearing upon the science of medicine, or, on the other hand, are too brief to be of any service to him. It has been the aim, in preparing this book, to avoid these extremes and fill the gap now existing between them. The plan of the work required a careful selection from the mass of material at hand. The book is largely a compilation, and the author claims little originality in the subject matter it contains, but has used his own judgment in its selection and arrangement. From the large number of subjects treated, it has been neces- sary to be very brief in the descriptions of individual sub- stances, but all general principles, and the relations of the facts of the science to medicine have been more fully stated. Much pains has been taken to condense the matter as much as is consistent with clearness. In Part I are presented such fundamental facts in Chemical Physics, as seemed necessary for the proper understanding of the descriptive parts, and to explain the theory and use of thermom- eters, the spectroscope, medical batteries, etc. It has been found best, in the author’s past experience, to present the elementary theories of Chemistry before entering upon tbe natural history of the elements and their compounds; III IV PREFACE. and this has been done as clearly and concisely as possible in Part II, giving only what was considered necessary to the proper understanding of all the facts to be presented in the later parts. The subjects of Notation, Nomenclature and Chemical Reactions have been dwelt upon as of first importance to the student. In Part III, the natural history of the Elements and principal compounds are briefly presented, with their physiological and toxicological bearings. In Part IV, only those organic compounds are treated, with which the physician will be likely to meet. The space that could be given to this part necessitated very short descriptions. The appendix contains some tables and analyses which will greatly enhance its value as a reference book. The Chemistry of the tissues and secretions have been omitted, as belonging to the domain of physiological chemistry. It would be impossible to mention all the works upon which the author has drawn for his facts. Besides the credit given in the text, he wishes to acknowledge his indebtedness especially to Cooke’s Chemical Philosophy, Barker’s, Richter’s, Witthaus’, Fowne’s and Rand’s text-books ; De Watteville’s and Jenkins’ books on electricity; Prescott’s Proximate Organic Analysis; Wurtz’ Diet, de Chem. and Chemie Biologique; Charles’ Physiolog. Chem.; Schorlem- mer’s, Strieker’s and Pinner’s Organic Chemistry, and the U. S. Pharmacopoeia. I would here express my thanks to my friend and assistant, Dr. W. M. Hutchinson, for valuable assist- ance in preparing the work; also to Mr. W. H. Kent, Ph.D., for similar assistance. As this work is prepared especially for the medical student, it is to him that I shall trust for its reception, hoping that the labor I have bestowed upon it may help to lessen his. Brooklyn, N. Y., Sept. 1st, 1885. CONTENTS. PAGE Introduction—Definitions 9 Matter, Properties of..... 9 Specific Gravity 11 Metric System 14 Chemical Physics 16 Three States of Matter 16 Constitution of Gases 17 Laws of Gases 19-21 Heat, Nature of. 22 Boiling Point 24 Distillation 25 Latent Heat 26 Specific Heat 27 Thermometers. 28 Light 29 Spectrum and Spectrum Analysis 31 Electricity 36 Theory of Galvanic Cell 38 Electric Currents » 39 Forms of Cells 40 Care of Batteries 42 Ohm’s Law 44 Induced Currents 45 Induction Coils 46 Magneto-Electricity 48 Thermo-Electricity 49 Static Electricity 50 Electro-Metallurgy 52 Solution 55 Diffusion of Liquids 56 Dialysis 57 Crystallography 57 P A IIT I. PART II. Theoretical Chemistry 63 Properties of Molecules 63 Table of the Chemical Elements 64 Properties of Atoms 69 Chemical Notation 71 Compound Molecules Classified 76 Nomenclature, Rules of. 79 Nomenclature Simplified 80 Chemical Reactions and Equations 83 Stochiometry 86 V VI CONTENTS. PART III. PAGE Inorganic Chemistry 89 Classification of the Elements . 89 Hydrogen 91 Oxygen 94 Hydrogen and Oxygen—Water 97 Natural Waters 101 Water Analysis 104 Chlorine Group Ill Fluorine Ill Chlorine 112 Bromine..... 116 Iodine 117 Sulphur Group 119 Sulphur 119 Nitrogen Group ’ 128 Nitrogen 128 The Aimosphere 129 Disinfectants, Antiseptics and Germicides 132 Phosphorus 143 Arsenic 149 Arsenic Poisoning, etc 153 Antimony 158 Bismuth , ' 162 Boron 164 Silicon 165 Carbon 166 Cyanogen 176 The Alkaline Metals 180 Lithium 180 Sodium 181 Potassium 187 Rubidium and Caesium 194 Ammonium Compounds... 194 The Metals of the Alkaline Earths 197 Calcium 197 Strontium 201 Barium 202 The Magnesium Group 203 Magnesium 203 Zinc 205 Cadmium 207 The Iron Group 208 Chromium 208 Manganese 210 Iron 212 The Nickel Group 218 Nickel..... 218 Cobalt 219 The Lead Group 219 CONTENTS. VII The Copper Group.. 224 Copper.... 224 Mercury 229 Silver 235 Gold 237 The Aluminium Group 238 The Platinum Group 240 The Molybdenum Group 241 PART IV. Organic Chemistry . 243 Homologous and Isologous Series 245 The Paraffines (1st Series) , 247 The Olefines (2d Series) 248 Acetylenes (3d Series) 249 Fourth Series 249 Camphors 250 Resins, Gums and Balsams 252 Benzol Series 253 Naphthalene and Anthracene 253 Alcohols 256-259 Ethers. 256 Aldehydes 257 Ketones 258 Acids , 258 Methyl Alcohol 259 Ethyl Alcohol . 261 Alcoholic Beverages 263 Amyl Alcohol (Fusel Oil) 264 Glycerine 265 Hexatomic Alcohols 266 Carbohydrates 267 Cane Sugar 4-A'V.. V£v\.... 268 Milk Sugar (...„. 269 Glucoses (.... 270 (rtarche.) 271 Glycogen 272 Cellulose 273 Gums 274 Ethers 274 Ether, Ethyl 275 Ethers, Compound 276 Organic Acids 277 Formic Acid ... 278 Acetic Acid 278 Butyric Acid 280 Valeric Acid 281 Oleic, Palmitic and Stearic Acids ;..... 282 Oxalic Acid 283 Succinic Acid 283 VIII CONTENTS. Organic Acids—{Continued). page Malic Acid 284 Tartaric Acid 285 Citric Acid 286 Carbolic or Phenic Acid 287 Picric Acid 288 Pyrogallic Acid ” 289 Benzoic Acid 289 Salicylic Acid 290 Hippuric Acid 291 Uric Acid 291 Organic Bodies Containing Nitrogen 291 Amines, Amides, Imides and Nitriles 291 Natural Organic Bases, or Alkaloids 294 Properties of Alkaloids. Table of Solubilities 295 Description of the Principal Alkaloids 297 Ptomaines, or Cadaveric Alkaloids 300 GHucosides 301 Natural Fats and Oils 304 Proteids ; !””””’ 305 Albumins 393 Globulins 393 Haemoglobins 393 Derived Albumins ' !.... ! 309 Peptones 310 Collagens .. 311 Biliary Compounds 312 Vegetable Coloring Matters !!!!!!!!!!!!!!!".!!'!!!!!! 315 Unclassified Compounds of Animal Origin...!.!!....!........ 317 Soluble or Albuminoid Ferments !!!!!!!!!!!!!! 318 Organized Ferments 321 Poisons and their Antidotes !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 322 appendix. Analysis of Blood 329 Lymph .!.!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!! 329 Chyle 330 Saliva . 330 Gastric Juice* 330 Pancreatic Juice !!!!!!!!!!!!!! 331 Post-mortem Bile !!!!!!!!!!!!!!!!!!!! 331 Human and Cow’s Milk J....!!!!!!!!!!!!!!!!! 331 Tears 332 Sweat 332 Composition of the Urine of 24 hours, with Pathological Variations... 332 Table of Weights and Measures 334 Equivalent Measures 335 Specific Gravities named in the U. S. Pharmacopoeia, 1880... 336 Solubility of Chemicals in Glycerin 337 Solubility of Chemicals in Water and Alcohol 338 Incompatibles 343 Glossary of Unusual Names of Chemical Substances 345 MEDICAL CHEMISTRY PART I. INTRODUCTION. 1. DEFINITIONS.—Science is a systematic and orderly arrangement of knowledge. It is founded upon observation and experiment. A theory is a deduction from established facts, and occupies a prominent place in science. A hypothesis is a supposition brought forward to explain facts or phenomena. Natural science treats of the external appearance and internal structure of natural objects. Examples: Botany, zoology, and mineralogy deal with the classification and structure of plants, animals and minerals respectively, and are, therefore, natural sciences. Physical science treats of the properties and phenomena of the matter of which these bodies are composed. Matter is anything whose existence is revealed to us by our senses. The properties of a body are the peculiar qualities by which it makes itself known to us; as color, solidity, odor, taste, etc. Physics is that branch of physical science which treats of the phenomena presented to us by bodies or masses of matter as such. Chemistry is that branch of physical science which treats of the ultimate composition of bodies, and the changes which this composition may undergo. Physics teaches us that water is hot or cold ; that it may exist as steam, liquid water, or solid ice. Chemistry tells us that it is composed of two gases called hydrogen and oxygen, in the proportion of two of the former to one of the latter, by volume, and one of the former to eight of the latter, by weight. It also teaches us how we can prove this to be true. Matter exhibits certain properties which are common to all bodies, and which are hence called the general properties of matter; such as indestructibility, impenetrability, divisibility, mobilitv, gravitation, molecular attraction, chemism and inertia. Specific properties are such as are observed in certain bodies only ; such as color, hardness, fluidity, transparency, etc. 9 10 MEDICAL CHEMISTRY. 2. Matter is Indestructible.—What we generally term destruction is merely a change of form. When wood burns, it is only changed into invisible gases which go off into the air. These gases may be collected, and by analysis we may get back the ele- ments of the wood again. Whatever changes we may produce in a body or mass of matter, we can neither create nor destroy one particle of it; the same weight of matter remains after the change as before. 3. Matter is Impenetrable.—That is, two portions of matter cannot occupy the same space at the same time. Strictly speaking, this only applies to the ultimate particles of a body. In many phenomena bodies do seem to penetrate each other. For instance, the volume of a mixture of sulphuric acid and water, or of alcohol and water, is less than the sum of the volumes before they are mixed. In these cases the penetration is only ap- parent. The penetration of the water by the alcohol is due to the fact that water, like all other bodies, is porous; that is, it has spaces or interstices between the ultimate particles of which the mass is composed, which are unoccupied by matter, and into which the particles of alcohol crowd themselves. 4. Divisibility.—Three divisions of matter are recognized, viz: masses, molecules, and atoms. A mass or body is any distinct portion of matter appreciable to the senses. A molecule (a little mass) is the smallest particle of matter that can be obtained by subdividing a mass by mechanical or physical means. It may also be defined as the smallest particle of matter that can exist in the free or uncombined state. A molecule of chalk is the smallest particle of chalk that can exist. The molecules are too small to be seen by the aid of the most pow- erful microscope, nevertheless their size is approximately known.* An atom is the smallest particle into which any given kind of matter can be divided. The atom is, as yet, a hypothetical body. It is one of the component parts of a molecule, and the smallest particle that can enter into the formation of a molecule. The atom is,'therefore, supposed to be an indivisible solid body, with a definite and unchangeable weight, possessing a definite quantity of force of attraction for other atoms, which force is neutralized by the approach of the requisite number of atoms. Atoms, when left to themselves, will not, as a rule, remain uncombined, but collect together in groups by their attraction * See Art. 15. DEFINITIONS. 11 for one another. A collection of atoms forms a molecule, and a collection of molecules forms a mass. 5. Mobility.—All matter is in a state of constant motion. The motion of masses, or mechanical motion, is treated of in works on mechanics. The motions of molecules give rise to the phenomena grouped under the name of the so-called Physical forces. Light, heat, electricity, and magnetism are dif- ferent manifestations of the motions of the molecules composing the body which exhibits them. Of the motions of atoms little is known with certainty. 6. Gravitation is an attraction which exists between masses of matter. The law of gravitation states that the force of gravitation is directly proportional to the mass, and inversely proportional to the square of the distance. By mass, here, we mean the weight of matter, and not the volume. By Specific Gravity (sp. gr.) is meant the relative weight of equal volumes of bodies, assumed to be under like conditions of temperature and pressure. For the purposes of comparing the weights of equal volumes of different bodies, they are all referred to an assumed standard. The standard for liquids and solids is pure water weighed at a temperature of 4° C. (39° F.), the temperature at which it possesses the greatest density or specific gravity. Density is sometimes used as synonymous with specific gravity. Sul- phur, whose specific gravity is 2, weighs twice as much, volume for volume, as pure water; while alcohol, whose specific gravity is 0.825, weighs 0.825 times as much as pure water, volume for volume. In taking the specific gravity of gases or vapors the standard of com- parison is pure, dry air. In chemistry, however, it is more convenient to refer specific gravities of gases to hydrogen gas, and designate this as the density and not the specific gravily, which term refers to air as the standard. The density of hydrogen gas is 1. The density of pure air is 14.42, i. e., air weighs, volume for vol- ume, 14.42 times as much as hydrogen, both gases being weighed at the same temperature and under the same pressure. Density is a very important factor in the study of chemistry, and should be well understood. The sp. gr. of solids may be determined by first weighing the body in the air, and then in water at the required temperature. A body which sinks in water displaces a volume of water equal to its own, and loses a weight just equal to the weight of water displaced. The loss in the weight of the body when weighed in water, will, therefore, be 12 MEDICAL CHEMISTRY. the weight of its own volume of water. By dividing the weight of the body in air by the loss of weight in water, the sp. gr. is obtained. Thus, suppose a body weigh 6.200grms. in air, and 3.100 graas. in water. The loss of weight in water is 6.200 — £.100 = 3.100 grins., which repre- sents the weight of the water displaced by the body, or the weight of its volume of water. The specific gravity of the body will then be found by dividing its weight in air, or 6.200 grms., by the weight of an equal volume of water, or 3.100 grms., giving a specific gravity of 2. When the body in question will not sink, we may attach a sinker to it, whose weight in air and loss of weight when sus- pended in water are known. The weight of the body in air is taken, the sinker attached, and both lowered into the water and again weighed. The loss in weight will represent the loss of weight of both the solid and sinker. Deduct the loss in the sinker, and the remainder will represent the weight of a volume of water equal to that of the body in question, whence the specific gravity may be found as above. Bodies which are soluble in water may be suspended in some liquid of known specific gravity, in which they are insoluble. Thus, let it be desired to obtain the specific gravity of a lump of cane sugar. Suppose it weighs in air 100 grms., and in oil of turpentine (sp. gr. .87) 45.62 grms. Loss — 100 — 45.62 = 54.38 grms. 100 -f- 54.38 = 1.84 as the sp gr. referred to turpentine. Multiply tins result by .87, the sp. gr. of the turpentine, and we have 1.6 as the true sp. gr. of the sugar. The sp. gr. of a powder is obtained by partly filling a small flask or bottle with it, and weighing both; the weight of the flask empty, as well as the weight of water it will contain, hav- ing been previously ascertained. The flask is then filled up with pure water and again weighed. The difference between the last weight and the first will be the weight of the water in the flask. The difference between this weight and the weight of the amount of water the flask will contain when full, will give the weight of the water displaced by the powder, from which the sp. gr. may be obtained as above. The specific gravity of liquids is obtained by means of the flask above-mentioned, called a picnometer or specific gravity flask, made to contain a certain number of grammes or grains of water at a temperature of 60° F., its capacity being marked upon it. (See Fig. 1.) To take the sp. gr. of a liquid, it is only necessary to weigh the flask, filled with the liquid in Fig. 1. DEFINITIONS. 13 question brought to the requisite temperature, deduct the weight of the flask, and divide this result by the marked contents of the flask. The specific gravity of liquids is frequently deter- mined also by an instrument called a hydrometer. Hydrometers are long narrow glass or metal tubes, with a bulb near the bottom filled with air, and a smaller one below this containing enough mercury or small shot to make it float upright and to sink it to a convenient depth in water. The hydrometer (See Fig. 2) acts upon the principle of Archimedes, that a body specifically lighter than a liquid sinks in it until it displaces a bulk of liquid whose weight is equal to its own, when it becomes stationary. The long narrow stem composing the upper end of the instrument bears a scale indicating the specific gravity by the depth to which the scale sinks in the liquid. Hydrometers are of two kinds : (1) for fluids heavier than water, and (2) for fluids lighter than water. Special hydrometers are constructed for use in certain special liquids, and some with an arbitrary scale giving degrees and not specific gravity. The Twaddell hydrometer, for example, used for liquids heavier than water, is so graduated that the degrees on the scale multiplied by 5 and added to 1000 give the specific gravity compared with water. The Lactometer is a hydrometer with a scale specially constructed for the examination of milk. The Urinometer is a hydrometer whose scale is made to include the variations in specific gravity found in urine. To determine the specific gravity of liquids with the hydro- meter, it is only necessary to drop the instrument into the liquid, which must be at the temperature for which the instrument is constructed, which, in this country, is usually 60° F., and then read off the specific gravity on the scale at the surface of the liquid. (See Appendix, for table of sp. gr. of chief liquids of U. S. P.) 7. Molecular Attraction.—Molecules attract one another, as well as masses. When molecules of the same kind attract one another, they form a homogeneous mass, and the force acting between them is called cohesion ; when the molecules are unlike it is called adhesion. A body on being thrust into water comes out wet, because the water adheres to the body ; but if you attempt to pull it apart, cohesion keeps it together. 8. Chemism.—Atoms attract one another by a force called Fig. 2. 14 MEDICAL CHEMISTRY. chemism or chemical affinity. Chemism holds atoms together to form molecules. It is to the molecule what cohesion is to the mass. Like cohesion it only acts across inappreciable spaces. 9. Inertia is that property of matter by virtue of which it has no power in itself to change its condition. [This term is often incorrectly limited to the tendency of a body when in motion to remain in motion, and when at rest to remain so.] Chemical or physical changes never take place without the inter- vention of some external agency. • 10. Extension is that property of matter by virtue of which it occupies space. Its relative degree is obtained by means of weights and measures. The system of measures and weights most in use in all scientific works is that known as the metric or decimal system. In most American and English medical books, though not in all, the English system is employed, while all nations of continental Europe use the metric system ; so that it is requisite that the student should be familiar with both. The unit of the metric system is the metre. The metre is the length of a platinum bar deposited in the public archives of France, and is 39.37 inches in length. This measure was obtained by taking the 10,000,000th part of the quadrant of a meridian of the earth, or of the distance from the equator to the pole. The ratio of increase and decrease of the system is decimal, and this system is consequently sometimes known as the decimal sys- tem. The multiples in all the measures and weights are denoted by Greek numerals, used as prefixes, as will be seen by reference to the tables on page 2 of the Appendix. Thus, in measures of length we have the metre, dekametre, hectometre and kilometre. The subdivisions are denoted by the Latin numerals, thus: metre, decimetre, centimetre and millimetre. Greek. Latin. English. Deka. Decern. Ten. Hekaton. * Centum. - One Hundred. Chilios. Mille. One Thousand. Murias. Ten Thousand. The decimal subdivisions and multiples give a simplicity to the tables which enables them to be easily learned and remem- bered, and brings into use in all calculations the easiest arith- metical processes. In square measure, measures of capacity, and measures of volume, but few denominations are in common use, and these only are given in the table. DEFINITIONS. 15 The litre, or cubic decimetre, is equal to 1000 cubic centi- metres. The cu. centimetre (abbreviated c. c.) and tenths of c. c. are the only denominations in common use for quantities less than the litre. The half-litre and quarter-litre are also used. Measures of weight are derived from measures of volume, as follows:— The gramme, the unit of weight, is the weight of 1 cubic centimetre of distilled water, weighed in a vacuum, and at the temperature of 4° C. (39.2° F.), the temperature at which water has the greatest density. Theoretically, the unit of weight is derived from that of capacity, as above; but the gramme is really determined by reference to an original standard kilogramme weight adopted by the French government. The capacity of vessels is determined, not by measure, but by weighing the water they will hold at a selected temperature. A litre measure is, therefore, a vessel that will hold exactly a kilogramme (1000 grms.) of pure water at the temperature at which it is to be used. Measuring instruments are usually made of glass, and are made to hold their marked contents at a tem- perature of 60° F. (15.5° C.) The following table will be found convenient to memorize, in order to facilitate mental calculations where approximate values only are desired :— 1 Metre = 39.37 in. = 31 feet. 1 Decimetre = 1C centimetres = 4 in. 1 Litre — .88 quarts = If pints. 1 Gramme = 15J grains. 1 Kilogramme = 2 lbs. avoirdupois. 1 Grain = .065 grammes, j or fgj = 4 grms. or 4 c.c. or f%j — 30 grms. or 30 c.c. 11. The Metric System in Prescriptions.—In prescrip- tion writing it will be found convenient to adopt the following rule where the doses have been learned in grains: Make f.?j equal 30 c.c. In a two ounce mixture, when a teasjpoonful is to he given as a dose, write as many grammes as there are grains or minims required in each dose. ' Thus, suppose it be desired to write for a two ounce mixture containing 15 grains of potassium bromide in each f3j, it would be wrritten :— Grammes. R. Potass. Bromidi 151000 Aquae 60l000 or 60 c.c. M. Sig.—4 c.c. ter die. 16 MEDICAL CHEMISTRY. A f 3 iij mixture would be written with one and one-half times as many grammes as there are grains required in each dose:— Grammes. R. Potass. Bromidi 221500 Aquae 901000 or 90 c.c. M. Sig.—4 c.c. ter die. The perpendicular line is used here to occupy the position of the deci- mal point, and separate grammes from milligrammes. It is customary among some pharmacists to weigh all quanti- ties written as above, instead of measuring them. In such cases, it is well to remember that liquors are very nearly the same specific gravity as water, excepting those containing the salts of the heavy metals. The syrups and glycerita have a sp. gr. of about 1}. The tinctures have a sp. gr. of about .9. In cases of doubt about the sp. gr., direct the quantity in c.c., when it will be measured. CHEMICAL PHYSICS. 12. We have already spoken of the divisions of matter into masses, molecules and atoms. The physicist deals principally with the properties of bodies or masses of matter which depend upon behavior of the molecules, without inquiring of what ate ms they are made up. Hence, when a piece of iron is moulded into this or that form, or melted and cast, or tiled, or ground to powder, it still remains iron. It may be hot or cold, it may be charged with magnetism or electricity, but it is iron still, and nothing else. These properties of color, solidity, tenacity, malleability, fusibility, power of being magnetized, and of con- ducting electricity, all depend upon the behavior of the mole- cules of iron, and are called physical properties. 13. Three States of Matter.—The same body may exist in three states; as a solid, liquid, or gas. Most solid bodies can be changed into the liquid or gaseous state by the application of heat to them. For example, when ice is heated, it melts and assumes the liquid form ; if we apply heat to the water, it ex- pands, is converted into steam, and tends to escape from the vessel containing it. If we confine the steam, it exerts a strong pressure upon the walls of the vessel, which increases as the tem- perature increases. This and other similar facts have led to the adoption of the word force to express the nature of heat. The term heat force may often be found in works on physics. The capacity which this force possesses of performing work is known as energy. Cohesion has been defined as that force or attraction CHEMICAL PHYSICS. 17 which acts between similar molecules to hold them together to form a body or mass. From the above illustration, we see that heat, whatever it may be, acts in opposition to cohesion, and even destroys it altogether, driving the molecules apart, and finally off into space. We have in this, then, the explanation of the three states of matter. In the solid state, cohesion is greater than the opposite repellant force of heat, and the mole- cules are in very close apposition. In the liquid state, cohe- sion and the repellant force are nearly equal, the molecules being free to move in any direction, arid obey the law of gravity; i. e., they all tend to seek the lowest level. In the gaseous state, the repellant force of heat has entirely overcome the attraction of the molecules for one another, hence, they tend to fly off into space, and will do so unless confined in a vessel. If we with- draw the heat from a gas, or if we compress it sufficiently, we may reduce it to a liquid, and in many cases to a solid ; i. e., we bring cohesion into play again. It will be easy to understand from the above, that the mole- cules must be farther apart in steam than in water, and in water than in ice. What is true of water, is true of all bodies capable of existing in the three states; for heat expands all bodies, whether solid, liquid, or gaseous, although not to the same degree. Gases expand more than liquids or solids for the same change of temperature. Gases are more simple in their consti- tution than either of the other states, and hence we get a better knowledge of their structure. 14. Constitution of Gases.—Law of Avogadro or Ampere.—This law states that equal volumes of all bodies in the state of gas, and at the same temperature and pressure, contain the same number of molecules. As a necessary deduction from the law, it follows : 1st. That all gaseous molecules occupy the same space. 2d. That the weights of equal volumes of any two gases are to each other as the weights of their molecules ; or, in other words, the specific gravities of any two gases must be to each other as the weights of their molecules. This law is of vast importance to the chemist, and is considered the basis of most of the modern notions of chemistry. Although it would be out of place here to enter into such a discussion, this law is capable of mathematical proof, starting with the assump- tion that masses are composed of molecules in a state of motion. 15. Size and Weight of Molecules.—That molecules actually exist, and that they are in constant motion in straight 18 MEDICAL CHEMISTRY. lines within the gas, there seems to be at present little room for doubt. Various recent experiments, drawn from many sources, have given us proofs of these facts. Starting from certain well established facts, physicists have been able to calculate the abso- lute number of molecules in a given space, their absolute weight, size, velocity, and the spaces between two neighboring molecules. What was at first a mere hypothesis is fast becoming a demon- strated fact. According to these calculations, a cubic centimetre of air contains twenty-one trillions of molecules ; and according to the law of Avogadro, all other gases must contain the same number in the same volume. 10 trillions of air, or 144 trillions of hydrogen molecules, will weigh 1 milligramme. The mean velocity of the molecule of air at 0° C. (82° F.) is 485 metres (1591 ft.) per second ; and of a molecule of hydrogen gas is 1844 metres (6050 ft.) per second. Of course, with this inconceivable number of molecules in the small space of one cubic centimetre, and all moving at the velocity mentioned, no one molecule could move long in one direction without colliding with another molecule. The number of shocks that each molecule receives, in the case of hydrogen gas, has been calculated to be 9480 millicns per second, while the mean distance r molecule moves in its path before colliding, is about .0001855 mm., which may be taken as the distance between two molecules. The diameter of the water molecule = .00000044 mm. Free path = .0000649 mm. Al- though these numbers give us no real conception of the magnitudes they represent, they are given here to show the tendency of research, and the advances being made. These numbers apply to gases only. 16. Radiant Matter.—When the pressure is removed from gases, the molecules are allowed to go farther apart; and while the distance between the molecules of air at the ordinary atmos- pheric pressure is a little less than a ten thousandth part of a mm., it may reach several centimetres when the pressure is reduced by a vacuum pump to a millionth of an atmosphere. Such a rarefied gas has new properties, and has recently received the name of radiant matter, by Mr. Crookes. Under the influ- ence of a ray of light, or an electric discharge sent through the rarefied gas (pressure one millionth of an atmosphere), the charged molecules, in the case of electricity, seem to launch forth in a direct line from the negative pole towards the positive. If a light disc be placed in this path, it is bombarded by these mole- cules on the side presented to the negative pole, and thus it receives a sufficient impulse to render the motion visible to the eye. In this manner the movement of the radiometer is explained.* We are now in a position to understand the laws of gases. * Wurtz, Diet. Sup., p. 249. CHEMICAL PHYSICS. 19 17. Law of Mariotte.—This law is stated as follows : The volume of a confined gas is inversely proportional to the pressure brought to bear upon it; that is, the less the pressure the greater the volume, and the greater the pressure the less the volume. Stated algebraically this law is : P: P':: V': V, whence V' = in which expression P and P' stand for two different pressures, and V' and V for the corresponding volumes. The pressure exerted upon any mass of gas is usually that of the surrounding atmosphere, and is measured by a barometer. The normal pressure of the air is about 15 lbs. to the square inch, or such that it will support a column of mercury 760 mm. (30 inches) in height. In the expression of pressures, as measured by this in- strument, the height of the column of mercury is employed instead of the weight of the column. Thirty inches of mercury is used, instead of 15 lbs. pressure. Substituting this form of statement in the above expression, it becomes V : V' :: H' : II and V' = VH“, or YII = V' H' in which H and H' stand for the height of the barometric column. Example.—A certain volume of air, at a pressure of 742 mm., meas- ures 540 c. c. ; what will it measure at 760 mm ? By the above formula we will have V/ = -07*074- = 527.2 c. c. ; or 540 c. c. : x :: 760 : 742 in which x = 527.2. Since a gas undergoes such great variation in volume under varied pressures, it is necessary to state the pressure when a given volume of gas is mentioned, or as is commonly done, to have an arbitrary standard of pressure under which all gases are supposed to be measured when not otherwise stated. The pres- sure which has been adopted is 760 mm., or 30 inches of baro- metric pressure. This is called the standard pressure. 18. The Law of Charles.—Not only does the volume of a gas vary with the pressure, but it also varies with the temper- ature. The hotter the gas the greater is its volume, and the cooler the gas the smaller the volume; or, as this law is usually stated, the volume of a gas varies directly with the absolute temperature. This is known as the law of Charles. All gases expand or contract equally for the same increase or decrease of temperature. A gas expands *73- of its volume in passing from 0° to 1° C. or of its volume for one degree Fahrenheit. Now, since a gas expands of its volume at 0° C., for every degree increase of temperature above zero, we may regard a gas at 0° C. as hav- ing been warmed through 273° C. In other words, 273° below zero mus- 20 MEDICAL CHEMISTRY. be regarded as the absolute zero, at which temperature all gases should be reduced to liquids, or to the smallest possible space. If, therefore, 273 be added to the temperature of a gas, we obtain the absolute temperature, or the number of degrees it is above the absolute zero. Bearing this in mind, the law of Charles may be stated as follows: 273 + T. =■ temperature of gas when measured : 273 + T/ the altered temperature :: V. the measured volume of gas : V/ the new or required volume. Or, T° : T0/ :: V : V' when T° & T0/ stand for the absolute temperatures. Example.—A given volume of gas at 20° C. measured 55 c.c. What would it have measured at 0° C. ? Statement.—273 -f- 20 : 273 + 0 :: 55 : x, the required volume. Or, 293 : 273 :: 55 : x = 51.2. Ans. Now, since the fraction ijfj- when reduced to the decimal form becomes .003665, it is plain that 1 c.c. of any gas at 0°, becomes 1.003665 c.c. at 1° C., 1.00733 at 2° C and 1 + n times .00366 at a temperature of n° C. Whence, the formula maybe stated: V/ or the new volume, equals V, or the known volume, multiplied by 1 + (.00366 X (T/—T); in which T and T/ stand for the observed and required temperatures respectively. The statement of the, above example would be, then :— .00366) (20—0) . V' = 55 X (1 + -00366 X 20) Since V/ and V are common to this equation and the one used in the last section for correcting the volume of gases for changes of pressure, we may combine the equations, when we have V/ = V X (1 + .00366 (t'-t) Xgo which may be used for corrections for both temperature and pressure. Example.—A given volume of air at 740 mm. and 15° C. measured 452 c.c ; what will it measure at 760 mm. and 0° C. ? Substituting, we have V' = 452 X (1 — -00366 X 15 X ft# = 415.8 +.) 19. Standard Temperature and Pressure.—Variations of temperature and pressure produce such important variations in volume, that it is frequently necessary, when comparing ob- servations, to reduce them to some standard temperature and pressure. The standard temperature used by most scientific men is 0° C. But 60° F. corresponding to 15.5° C., being about the ordinary temperature of the air, is sometimes found to be more convenient, and is frequently used. By standard con- ditions of temperature and pressure are meant 0° C. and 760 mm. pressure. 20. Diffusion of Gases.—When two gases are brought together without an intervening wall of separation, and allowed to remain at rest for a time, it will be found that they pass into each other and become mechanically ‘mixed, even when differing in specific gravity or density. This gradual mixing of gases is CHEMICAL PHYSICS. 21 called diffusion. The diffusion of gases will also take place if they are separated by a por- ous wall of earthenware, stone, or parchment, by the passage of the gas through the pores. A convenient method of illustrating this phenome- non is, to take an unglazed earthenware cup, such as is used in a Bunsen’s battery cell, invert it in a funnel provided with a long stem, and fasten it in place by a paste made of plaster of Paris. The lower end of the funnel tube is passed through a perforated cork into a bottle containing water, as shown in the accompanying figure. (See Fig. 3.) On bringing a bell jar of hydrogen or illuminating gas over the porous cup, the air in the funnel will be forced out below, and may be seen to escape through the water in bubbles. 21. Graham’s Law of Diffusion.—Ac- cording to this law, the velocity of diffusion of different gases is inversely proportional to the square roots of their densities. As an illustra- tion of the truth of this law, we may compare the rates of diffusion of hydrogen and oxygen. By measurement, it has been found that hydro- gen diffuses four times faster than oxygen. Their densities are known to be 1 and 16; and the square roots of these numbers are 1 and 4. It will thus be seen that the rates of diffusion are inversely as these last num- bers. Fig. 3. The phenomena of diffusion admit of easy explanation on the assump- tion that the molecules of gases are in a state of rapid motion. More- over, it is plain, since a given volume of all gases contains the same num- ber of molecules, at the same temperature and pressure, that the moving power of all molecules under like conditions must be the same ; for the pressure brought to bear on the gas is balanced by the impact of its molecules or its elasticity. To produce the same effect against the walls of the vessel, lighter molecules must move faster than the heavier ones. In mechanics, the moving power of a body is ex- pressed or measured by one-half its mass (weight) multiplied by the square of its velocity. Applying this to moving molecules, letting M represent the weight of the molecules,' we have the expression | M V2 expressing the moving power of the molecules ; or, as we shall learn later that the density of a gas is one-half its molecular weight, 2 M = D, whence we have | M V2 =' I) V2. Now, if the law stated above be true, we shall have for any two gases D V2 = D2 V2/. Whence, Y : V/ :: 22 MEDICAL CHEMISTRY. y/D/: \/D. Or the velocities of the molecules are to each other inversely as the square roots of their densities, which corresponds to the statement of Graham’s law. The densities of hydrogen and oxygen are known to be 1 and 16 respectively, and, therefore, the velocities of their molecules must be as the square roots of these numbers or as 4 to 1; or the mole- cule of hydrogen must move 4 times as fast as that of oxygen. The com- parative velocities of other molecules may be calculated in the same way, from their densities. 22. Nature of Heat.—As nearly as we can conceive, the phenomena and sensations to which we apply the term heat, are the manifestations to our senses of the motions of the molecules of matter, which we have partially discussed in the last sections. Besides producing the sensation of heat, it acts variously on bodies; it boils water, melts iron, makes the metals give out light, electricity, etc. It was formerly supposed that heat was a form of matter— a subtle fluid which could flow from one part of a body to another, or through the air. We still retain some of the forms of expression used while that theory was held ; such as conduc- tion, convection, absorption, emission, radiation, etc., the theory itself being entirely abandoned. We now regard heat as a manifestation of one form of molecular motion. The more rapid the motion of the molecules of any given body, the higher will be the temperature. Many of the phenomena of heat may be beautifully illustrated by means of a ball attached to an elastic India rubber string, held in the hand. The ball may represent the molecule, the string the elastic co- hesive force, which acts between molecules, and the force applied by the hand to make the ball revolve about it, the force of heat. 23. The Sources of Heat are the sun, stars, interior of the earth, chemical action, and the conversion of mechanical motion or molecular motion into heat. The earth receives but about the two thousand millionths of the heat of the sun, and the fixed stars are estimated to furnish about j as much heat as the sun.* The amount of heat annually received from the sun would melt a layer of ice surrounding the earth, 101 feet thick.* The internal heat of the earth has some effect upon our temperature, but not a very important one, as the crust of the earth does not conduct heat well. Chemical action is the most important arti- ficial source of heart. When the heat thus produced is intense, and accompanied by light, the bodies are said to burn. In an ordinary fire, the heat produced is due to the chemical action * Rand, p. 34. CHEMICAL PHYSICS. 23 going on between the oxygen of the air, and the carbon of the fuel. Animal heat is largely due to a similar cause ; that is, to chemical action going on in the muscles, glands, brain, and, in fact, all the tissues ; not, as formerly taught by Liebig, by direct combustion of the food by the oxygen of the air, but by oxida- tion of the different tissues whenever they are called upon to exercise their functions. Mechanical force may be converted into heat; as when the axle of a railroad coach becomes hot; or when the brakes are applied to the wheels; or when a piece of steel strikes a piece of flint. These phenomena may be imitated with the ball and string above mentioned, by allowing some one to strike the ball while it is swinging, so as to drive it faster on its course. This is what takes place when the steel comes in contact with the flint. 24. Mechanical Equivalent of Heat.—There is an inti- mate relationship between heat and mechanical motion. They are capable of being converted, the one into the other. The friction of the match against a roughened surface produces enough heat to ignite it. Heat, on the other hand, is converted into motion by the expansion of steam, which drives the steam engine. It has been determined that a certain amount of heat has its exact equivalent of work. The unit of work is the foot- pound—the force required to raise one pound one foot high ; and the unit of heat is the heat necessary to raise one pound of water from 0° to 1° C. This amount of heat, if it could all be made to do mechanical work, would be sufficient to raise 1390 lbs. one foot high; or the thermal unit is equivalent to 1390 foot- pounds. If we adopt as the thermal unit, the heat necessary to raise one pound of water from 32° to 33° F., it is equal to 772 foot-pounds. 25. Effects of Heat.—One of the first effects of heating a body is to expand it. This is the effect of heat upon all bodies, except in a few cases of apparent exception. Silver iodide is a notable exception to this rule. To understand just what takes place when heat expands a body, let us return to our ball and string; the more force we apply to it from the arm, the more rapidly the ball will move; as it docs so, the more it stretches the string and the larger the arc it describes. If we apply enough force the string will break, and the ball will fly off into space. 26. Melting and Freezing Points.—When heat is applied to the molecules, it drives them faster through their paths and further apart from one another, until finally the cohesive force is 24 MEDICAL CHEMISTRY. stretched to its utmost, and is on the point of breaking ; then the body melts and becomes a liquid, in which state the two forces are nearly equal, with cohesion slightly predominating. The temperature at which a body, usually solid, passes into a liquid state is called its melting point. If heat is abstracted from a body that ordinarily exists in a liquid state, cohesion more and more overcomes the heat force between the molecules until the body contracts and passes into the solid state. The temperature at which this takes place we call the freezing point of the body. If more heat is now applied, the cohesive force (represented by the elastic string above) gives way, the molecules begin to fly off into space, and we say the liquid boils or passes into the gaseous state. - 27. Boiling Point of Liquids.—The temperature at which a liquid gives off vapor rapidly from the whole liquid is constant for that liquid, and is called its boiling point. In giving a description of a liquid the boiling point is usually given. The boiling point of water is i00° C. (212° F.), and is nearly constant when this occurs in an iron vessel in the open air. It is slightly higher in a glass or other vessel with polished walls, because the steam adheres to such a surface until it becomes a little above that point, or slightly superheated. The pressure exerted upon the surface of the liquid may vary the temperature of the boiling point, by resisting the .expansive force of the molecules and aiding cohesion to keep them together. When considerable pressure is brought to bear upon a boiling liquid, its temper- ature rises until the tension of the steam overcomes this pressure, and it becomes superheated. Conversely, if the pressure be re- moved, or lessened, the temperature at which the liquid will boil is lowered. This may be illustrated by the experiment known as the culinary paradox, as follows:— Take a flask of water, and after boiling it vigorously for a few minutes, so that the rising steam may expel most of the air, cork it up with a tightly- fitting cork and the boiling will cease ; remove the lamp and turn the flask bottom upward. (See Fig. 4.) By pouring cold water on the flask the steam is condensed, the pressure is removed from the water, and it boils vigorously. Now, allow the steam to fill the flask above the water, and it Fig. 4. CHEMICAL PHYSICS. 25 ceases boiling again. A dash of cold water will again make it boil. This may be repeated until the water becomes cool enough to be held in the hand with comfort. The boiling point of water varies, then, with the height of the barometer, or with the pressure of the atmosphere upon it. As the height of the barometer falls in ascending from the surface of the earth, the boiling point of water must fall also. An ascent of about 1080 feet lowers the boiling point of water 1° C. By this means the height of mountains may be determined within a few feet. When a liquid passes off into vapor, it is said to evaporate. Evaporation takes place slowly and imperceptibly from liquids at temperatures below their boiling points. In the case of water, for example, there is some evaporation even from the surface of snow and ice. The moisture of the air, from which clouds, rain, snow, dew, etc., are formed, is carried up by this imperceptible evaporation. 28. Distillation and Sublimation.—When a liquid is rapidly evaporated and condensed again by means of cold, the process is called distillation. When water containing solid matters in solution is evaporated, the solids remain in the vessel while the water only is given off. By means of this fact, we are., able to prepare perfectly pure water by distillation. When a mixture of two or more liquids is heated, that having the lowest boiling point begins to evaporate or distill first, leaving the others behind. During the rapid evaporation of a liquid, its tempera- ture remains constant at the boiling point until it is all evapor- ated. To separate a mixture of liquids having different boiling points, it is only necessary to heat the mixture until that having the lowest boiling point begins to boil, and allow it to remain at that temperature until it has all passed over and been condensed. The condenser is now removed and another attached ; the temperature is now raised until another portion of the mix- ture begins to distill over, and so on until the liquids are sepa- rated. The first process seldom effects a perfect separation, owing to some heavier liquids being carried over by the lighter ones; a second or even a third distillation is often necessary. The above process is called fractional distillation. By the term destructive distillation is meant, a distillation usually of dry substances, so as to destroy them and obtain liquids or gases; as, for example, the distillation of coal for the purpose of preparing illuminating gas, and liquids to be used for various purposes; and the distillation of wood to pre- pare vinegar, wood spirit, etc. Distillation is carried on in a 26 MEDICAL CHEMISTRY. retort or still, and the vapor is condensed in a worm or condenser. The retort, or still, is the vessel in which the liquid is heated, and is made of glass, copper, iron, or platinum. (See Fig. 5.) The heat is applied to the retort or still until the liquid boils. The vapor from the boiling liquid passes through the beak of the retort into the condenser, which is always kept cool by means of cold water. A few solid bodies when heated do not melt and form liquids, but pass directly into the state of vapor. Such bodies are said to sublime, and the process is called sublimation. Iodine, sulphur, camphor, and ammonium chloride, are ex- amples of bodies which may be sublimed, and this process is usually employed for their purification. Fig. 5. 29. Latent Heat.—It is evident that a part of the heat force applied to a body is used up in overcoming the force of cohe- sion and in expanding the body, and does not appear in the actual moving power of the molecules. In our ball and string illustration (Art. 22), a part of the force applied to the string by the hand is expended in stretching the string, or finally in break- ing it, and does not appear in the moving power of the ball. This force which is expended in overcoming cohesion and in keeping the molecules apart, does not appear in the tempera- ture of a body. When air is heated and allowed to expand, about two-sevenths of the heat force is used up in expanding it. If we apply heat to a vessel containing ice, the temperature of the water formed is the same as that of the ice, although a considerable heat has been absorbed in the melting process. CHEMICAL PHYSICS. 27 When water is boiled it does not rise above 100° C. (212° F.) however hot the fire is; it remains at 100° C. until it is all evaporated. What has become of all the heat applied to the water ? It has been used to drive the molecules farther apart, and,is locked up in the water in the first case, and in the steam in the second. The heat thus expended is called latent heat. It requires heat to convert a solid into a liquid, or a liquid into a gas. The reverse is equally true; that heat is given out when a gas becomes a liquid, or a liquid be- comes a solid. Freezing mixtures are based upon this law. A mixture of salt and ice freezes, because the salt melts the ice by its affinity for water; but heat is absorbed by a solid when it becomes a liquid, and is taken up in this case from whatever happens to be in contact with the freezing mixture or vessel containing it. Ice machines operate on the principle that when a liquid evaporates, it absorbs large quantities of heat. A very volatile liquid is made to evaporate rapidly by removing the pressure from it by pumping out the vapor as fast as formed. A very low temperature is produced in this way in and about the vessel containing the liquid. Place a few drops of ether upon your hand and allow it to evaporate, and you will have a very good illustration of the heat absorbed by an evaporating liquid. Mitchell obtained a temperature of—146° F. with ether and solid carbon dioxide. Vatterer produced a temperature of —-220° F. with liquid nitrous oxide and carbon disulphide. 30. Specific Heat.—When equal weights of two given bodies are exposed to the same source of heat, they do not both rise in temperature with the same rapidity. That is, it takes more heat to raise a pound of water from 0° to 1°C., than it does to raise one pound of mercury through the same change of temperature. The relative amount of heat required to raise equal weights of substances through equal degrees of tempera- ture, is called their specific heat. Water has the highest specific heat of any known substance except hydrogen gas. The unit of specific heat is not everywhere the same. Some use as the unit of heat the heat required to raise 1 pound of water from 32° to 33° F., others from 0° to 1° C. The latter is the one most commonly used, and is called the thermal unit. In France, the unit is the calorie, which is the heat required to raise 1 kilogramme of water from 0° to 1° C. 1 Calorie = 2.2 thermal units. 1 thermal unit = 0.45 calorie. 31. Temperature.—From the preceding article it will be seen that the temperature of a body is entirely distinct from the amount of heat it contains. Temperature may be defined as the 28 MEDICAL CHEMISTRY. tendency a body possesses of imparting heat to surrounding bodies. It is this tendency which gives to our senses the im- pression that the body is hot or cold; it is, therefore, the measure of its sensible heat, or heat that is appreciable to our senses. The heat which a body contains is made up of its sen- sible heat plus its latent heat. The temperature of a body is increased or diminished by adding to or withdrawing from it sensible heat. As the number and weight of the molecules of a given body are constant, the variations of temperature must mean a variation in the velocity of the moving molecules. In our ball and string illustration it will be indicated by the velocity of the ball in its path. 32. Thermometers.—Temperature is measured by an in- strument called a thermometer. Thermometers are usually Fig. 6. Cei tigrade. Fahrenheit. Feaumer. Mercury boils Water boils Water freezes Mercury freezes.. constructed of a closed glass tube, provided with a bulb at one end, containing a liquid whose expansion or contraction is used to indicate the temperature. It is also provided with a scale to mark the amount of contraction or expansion taking place in the liquid. Liquids are usually chosen, as solids expand too little and gases too much to be convenient. The liquids commonly used are mercury or alcohol; of these the former is most exten- sively used, because of the long range of temperature between its freezing and boiling points. Pyrometers are instruments for measuring very high temperatures, and are constructed of metal, or tire clay, whose melting point is very high. The thermometric scales in common use are the Fahrenheit, Celsius or Centigrade, and Reaumer. The differences in these scales may be seen at a glance by reference to Fig. 6. There LIGHT, 29 are two fixed points in all of them—the temperature of melting ice, and that of the steam from boiling water. These two points must be determined on every instrument by actual trial; these points are marked on the glass with a file or diamond. It then remains only to divide the space between them into a certain number of degrees, according to the scale adopted. In the Centigrade or Celsius and in the Reaumer the freezing point of water is marked 0°, while in the Fahrenheit it is marked 32°. The point at which the mercury rises in the tube when the latter is plunged into steam from boiling water, is to be marked 100° in the Celsius, 2123 in the Fahrenheit, and 80° in the Reaumer. There remains, then, simply to divide the space between these points into 100 equal parts in the first, 180 in the second, and 80 in the third. Chemists generally have adopted the Centigrade scale, although some still adhere to the Fahren- heit, which is the one in common and almost universal use among the laity in this country. The Reaumer is not much used in this country, and we shall not use it in this book. It is not difficult to change the readings from one to the other scale. It will be seen that 100° C. == 180° F., 1° C. = 1.8° F., or 1° C. = |° F. and 1° F. = f° C. We must remember, how- ever, that the 0° mark in the Fahrenheit scale is 32 degrees below that of the Celsius; hence, in converting degrees F. to degrees C. we must first take from the reading 323 and reduce only those above the freezing point of water. While in changing degrees C. to F., we must add 32° to the result, to obtain the true reading. Thus, 10° C. = 10 X f = 18 + 32 = 50: and 41° F. = 41 — 32 = 9 X f = 5° C. Or, multiply degrees C. by § and add 32 = degrees F. ; and multiply degrees F. by f after subtracting 32 = degrees C. The Centigrade and Fahrenheit degrees will both be given in this book. LIGHT. 33. The second so-called physical force which plays an im- portant part in many chemical phenomena, is light. Accord- ing to the best conception we have of light, it is the effect upon the optic nerve produced by undulations of an exceedingly sub- tile and highly elastic form of matter, called the luminiferous ether. That this ether really exists, pervading the spaces between the molecules of all bodies, so many million times more elastic than air, so light that it offers no appreciable resistance to the earth moving 1100 miles a minute through it, is a hypothe- 30 MEDICAL CHEMISTRY. sis, merely, which has been advanced to explain certain well- known facts. That light passes from the sun and stars to the earth, no one can doubt; and yet, without some such assumption, we cannot conceive how it does pass, unless we hold to a former view, which taught that light was in itself a form of matter, without weight, given off by luminous bodies, and which is able to pass through glass, water, rocks, etc. These properties are contrary to all known laws of ordinary matter, as also are those of the ether assumed in the other theory. It is believed that undulations may originate in certain motions of molecules or atoms; that these motions or undula- tions are communicated to the ether and conveyed upon it in the form of waves; and that the movement described by a given particle of ether is in the main an oscillation at right angles or perpendicular to the direction of the ray, or beam. 34. Transmission of Light.—The motion of a ray of light travels along the line of particles, very much in the same way that it passes along the line of ivory balls placed in contact on the billiard table, when another ball strikes the end one directly in line with the rest. The motion or impulse passes along the line, but the one at the opposite end is the only one seen to move. It may be illustrated by placing a ruler on the table, holding it firmly in place with a marble in contact with one end, and with a hard body striking a short quick blow at the other. The stick does not move, as a whole, but the jar will be felt to pass under the hand, and the marble will move from its place. 35. Color and Intensity.—It is evident that these oscilla- tions may differ in rapidity or in their amplitude; i. e., comparing it to the movements of a pendulum, it may vibrate rapidly or slowly, and it may swing a long distance or a short one. Upon the extent and rapidity of these oscillations depend two import- ant differences in the effects of light on the organs of vision, viz., color and brilliancy ; the brilliancy depending upon the force of the blows upon the retina, and the color upon the number in a given time. We have an analogous fact in sound. Here we can more easily demonstrate the truth of the fact that the inten- sity of the sound depends upon the amplitude of the vibrations of the molecules, while the pitch depends upon the number of waves or pulsations which reach the ear in a given time. From well established data, we are able to calculate the rapidity of the oscillations which produce the different sensations of color, and the corresponding lengths of the ether waves. Some of these results are expressed in the following table:— LIGHT, 31 Color. length of Waves in Fractions of a Millimetre. Number of Oscillations in one second Red. 650 millionths. 477,000,000,000,000 Orange. 609 “ 506,000,000,000,000 Yellow. 576 “ 535,000,000,000,000 Green. 536 “ 577,000,000,000,000 Blue. 498 “ 622.000,000,000,000 Indigo. 470 “ 658,000,000,000,000 Violet. 442 “ 699,000,000,000,000 The color of an object depends upon the character of light it reflects or transmits to the eye. A beam of white light is com- posed of a variety of different colored lights mingled together, as can be shown by passing it through a prism of glass having an angle of 60°, by which it is decomposed into its component colors. When a body looks red to us, it is because it absorbs or destroys all the oscillations of the white light except those which give us the sensation of red light. If it be blue, only the vibrations that give us the sensation of blue light are reflected. Some bodies and solutions reflect one color, and transmit another very different one. The color transmitted is usually the comple- ment of the one reflected; i. e., if the two lights are mixed to- gether they produce the sensation of white light. If a solution of nickel salt'and one of cobalt are mixed together cautiously, the color of the one mixes with that of the other so as to form a colorless solution, because the colors are complementary. Fig. 7. 36. The Spectrum.—When a beam of white light is passed through a prism, as represented in Fig. 7, it is not only refracted, 32 medical CHEMISTRY. that is, bent from its original course, but the colors of which it is composed being unequally bent, are separated one from another. If now we allow them to fall upon a white screen, S, Fig. 7, they produce a series of blending tints upon it, which are called a spectrum. The red rays, which are least bent from their course, are said to be the least refrangible, while the violet are the most refrangible. Intermediate between these colors we find the orange, yellow, green, blue, and indigo. The prism thus gives us an easy means of analyzing a beam of light, to show the character of the rays producing it. Such observations are usually con- ducted by means of an instrument called a spectroscope. 37. The Spectroscope.—Figure 8 will illustrate the coo- Fig. 8. struction of the spectroscope. The light is received from the source of light (F), through a very narrow slit, regulated by a screw; it passes through the tube (A), called the collimator, and is directed upon the prism (P) which may be made of flint glass, or it may be made hollow and filled with bisulphide of carbon. In some instruments there are several flint glass prisms so arranged that the light is made to pass through all of them, so as to secure a wider dispersion of the rays than can be obtained with one prism. LIGHT. 33 The beam of light, after traversing the prisms, is viewed with the telescope (B). For purposes of comparison, an additional tube(C) is attached, bv which another light may be thrown upon the sur- face of the prism so as to be reflected through the telescope by the side of the light from F.* Many instruments now made are so arranged that the ray of light is not bent from its course in passing through the prism, and these are called direct vision spectroscopes. 38. Bright Lines.—When we view mono-chromatic light with the spectroscope, that is, a light composed of but one color, we see only a vertical image of the slit in B, and its position will depend upon the refrangibility of that color. If, on the other hand, we illuminate the slit with a light containing several rays of different degrees of refrangibility, we shall see one image for each ray present; and they will be separated from one another by their differences of refrangibility. The same color always appears in the same position with reference to the others. If we look at a solid body, heated till it emits a pure white light, there will be so many images spread out on the field of vision, that the one overlaps the other until there are no dark spaces between them, and thus gives a continuous spectrum, as it is called. If we place a light before the slit which emits very little light of its own, such as that given by a Bunsen burner, and then put into this flame a little sodium, which gives a pure yellow light, we shall see but one image of the slit, and that in the position occupied by the yellow, in the continuous spectrum, or the D line in the solar spectrum. If we use lithium instead of sodium, we get one image in the position occupied by the red ; if thallium I>e used,-the single image is seen in the position of the green. If we mix the three, we shall see the three images as bright lines, each in its own position ; one in the yellow, one in the red, and one in the green. In the better instruments, the yellow sodium line appears as two parallel lines. If we illuminate the slit with the vapor of a metal which emits rays of several different degrees of refrangibility, we shall see several images or bright lines in different portions of the field. Any given element always emits the same rays under like conditions ; hence, by use of the spectroscope, we may determine what element is introduced into the flame of the lamp by the lines we see in the telescope. 39. Solar Spectrum—Dark Bands.—If we illuminate the * F°r an explanation of the principle of lenses the student is referred to works on Physics. 34 MEDICAL CHEMISTRY. slit with the light of the sun, wre see almost a continuous spectrum marked by a number of dark lines, known as “ Fraunhofer’s lines,” the cause of which we shall refer to again. The most prominent of these dark lines have been designated by the letters of the alphabet, as will be seen on reference to the solar spectrum in the frontispiece. These lines serve as landmarks upon the spec- trum, by which we can fix the position of other lines, or by which we can designate the position of any line. The D line, for example, is the most brilliant, and can always be seen in the solar spectium. This serves as a starting point in mapping the spectrum, or as a guide in focusing or adjusting the telescope. 40. Spectrum Analysis.—The spectroscope is an important aid to chemical analysis when used with certain precautions, and w'ith certain well-known facts, in its use, kept in mind. We shall state briefly the principles upon which spectrum analysis is founded :— 1st. All bodies, when intensely heated, become luminous, and, other things being equal, the higher the temperature the more intense the light. 2d. Solid and liquid bodies, if opaque, emit when heated, first a red light, but as the temperature rises the other colors make their appearance, and finally predominate. If the tempera- ture reaches what is called a blue heat, the blue and violet begin to predominate. 3d. The elementary substances give {heir characteristic and peculiar light only in the state of gas or vapor. Hence, when we examine the light from any given source, we may conclude from a continuous spectrum that the heated substance is a liquid or solid, while a broken spectrum is due to a luminous gas or vapor; and, from the position of the bright lines, determines the nature of the substance giving the light. There are, however, a few exceptions to this principle. Under certain conditions even a gas may give off'a light that will give a continuous spectrum. 4th. At the temperature, at which gases or vapors become luminous, compound bodies, as a rule, break up into their con- stituents, i. e., the elemental atoms seem to be dissociated. For this reason, little is known of the spectra of compound bodies. 5th. At a high temperature the metallic atoms are much more luminous than the noil-metallic ones with which they are associ- ated. Hence, when we examine the vapor of a metallic salt rendered luminous, the light emitted is so exclusively that of the dissociated metallic atoms, that, whatever salt of that metal be used, we obtain essentially the spectrum of the metal itself. LIGHT. 35 6th. If, when the slit of the spectroscope is directed towards a source of white light giving a continuous spectrum, another flame giving a mono-chromatic light from a luminous vapor be inter- posed between the white light and the slit, a dark image of the slit will appear in the position where the vapor of itself would have given a bright line. That is, when the light from a liquid or solid luminous body is made to pass through a luminous vapor, those rays of light are absorbed which the vapor, of itself, emits. Hence, when we analyze the light of a distant source of light, and observe a continuous spectrum marked by dark lines, we may conclude that it is produced by a solid or liquid luminous body shining through a luminous vapor. This explains the dark lines seen in the solar spectrum. 7th. Many substances in solution absorb certain rays from a beam of white light passed through them, and the portions of the beam absorbed are peculiar to each substance. We thus have a means of detecting the presence of a few substances which cannot be rendered luminous, by passing a white light through the solution suspected to contain them. 41. Absorption Spectra.—When we wish to observe the spectrum of a liquid we place it in a glass tube, or preferably a vessel having parallel sides, and place this before the slit of the spectroscope. We now throw a strong white light through the solution and into the slit of the instrument. Solutions of erbium and didymium examined in this wray absorb certain portions of the spectrum given by the source of light. The particular portions °f light absorbed are peculiar to each, and in these cases the dark bands across the bright spectrum occupy the same positions in which the vapors of these elements give light bands. Absorption bands differ from the dark lines of the solar spectrum in being broader and not so sharply marked. They are often only a slightly darkened portion of a bright spectrum. Even passing the light through a crystal, in some cases, gives the same result as passing it through its solution. The use of the spectroscope in medicine and toxicology is chiefly confined to the observation of absorption spectra of various solutions. Some idea of the appearance of such spectra may be obtained by reference to the frontispiece, remembering that the spaces which appear white there are, in practice, occupied by the colors of the solar spectrum in their appropriate places.* * See Rosenberg or McMunn on the use of the spectroscope in medi- cine. 36 MEDICAL CHEMISTRY. 42. Chemical Effects of Light.—If a mixture of pure hydrogen and chlorine gases be prepared in the dark, and kept there, no combination takes place ; if the mixture be brought out into a light room, a gradual combination takes place and hydro- chloric acid is the result; if the mixture be placed in the direct rays of the sun, instead of diffused light, the combination takes place with an explosion. The light in this case causes chemical action. The electric light and other intense lights produce the same action. If a piece of white paper wet with a solution of nitrate of silver be kept in a dark room no change takes place in it; but if the paper is exposed to a strong light for a few min- utes, it begins to grow dark and finally becomes black. Many chemicals kept in the light are in time sensibly changed. Silver and gold solutions in presence of organic matter deposit a part of their metal in the metallic form. Nitric acid becomes slowly yellow, from the decomposition produced by the light. A solution of the syrup of the iodide of iron on exposure to air becomes brown from decomposition; but on exposure to the direct sunlight it again recombines and returns to the normal green color. The art of photography is based upon the changes produced in silver salts, gelatine, etc., by light. Sometimes the change seems to be a true chemical reaction, and in other cases it is a molecular change only. It has been found that it is not always the luminous part of the ray of light that effects these changes, but that they are chiefly produced by certain invisible rays found most abundantly beyond the violet part of the spectrum. From this it has been concluded that the light of the sun, as well as the light from some other sources, contains certain rays having this power to produce chemical changes. This action is known as actin- ism, and the rays producing it are called actinic rays. 43. Electricity Produced by Chemical Action.—If in a vessel of water, containing a little sulphuric or hydrochloric acid (1 to 20), a strip of zinc and one of copper or platinum be immersed and prevented from coming in contact, no action is seen to take place, provided the acid and zinc be pure. If, how- ever, we connect the two strips of metal by a wire, or the upper ends of the strips are brought in contact above the liquid, chemical action immediately takes place, and the following phenomena are observed: 1st. Small bubbles of gas are seen to collect on the surface of the platinum strip, while the zinc slowly dissolves, and at the same time the acid begins to disappear. In ELECTRICITY. ELECTRICITY. 37 the case of hydrochloric acid, the chlorine combines with the zinc, and the hydrogen escapes from the opposite plate. 2d. We shall find a peculiar property manifested by the wire, which is known as electricity. If a magnetic needle be placed near the wire it is turned from its course. If the wire be broken and the tongue be placed between the two ends, a tingling, metallic taste is observed. 3d. If the plates are large, and the ends of the wires are placed near together in a solution of copper sulphate, the metallic copper begins to deposit on one of the wires. In a word, a force is developed in the wires which we call electricity. If the wires are separated from each other by air the chemical action ceases, the gas ceases to escape, and the zinc to dissolve. The same phenomena are observed when we substitute for the above metals zinc and lead, zinc and gas retort carbon, etc. It is only necessary that the plates be unequally acted upon by the fluid in which they are dipped ; and the greater this difference, within certain limits, the stronger is the force developed in the wire. In order that these phenomena shall take place, the following conditions are necessary:— The plates and connecting wires must be conductors of electricity. The liquid must contain some substance with which one of the plates can form a chemical action. 44. Electrical Induction.—By this term is meant the property an electrified body possesses, of inducing or causing an opposite condition in certain bodies near it. This is a property of electricity that we must understand before we can compre- hend the action of the galvanic cell. If a magnet is brought near any piece of iron, as a nail, the latter becomes a magnet, with the poles in the same position as those of the original magnet. So, a piece of brass held near the prime conductor of a friction electrical machine, becomes charged with the opposite kind of electricity to that of the conductor. A negatively electrified cloud passing over the earth induces the opposite condition in objects directly under it on the earth. This condition of a body is generally known as polarity; i. e., the body manifests a peculiar force at certain points known as its poles. A magnet usually has two poles. The chief characteristics of this polar force are as follows:— 1st. The energy is chiefly exhibited at opposite points of the body, called its poles. 2d. Like poles repel and unlike poles attract each other ; and 38 MEDICAL CHEMISTRY. while like poles enhance each other’s effect, unlike poles neutral- ize each other. 3d. A polarized body induces a like condition in all bodies near it susceptible of this condition, a pole of a given kind inducing a pole of the opposite kind in that part of the body nearest to itself. 4th. Induction is attended with no loss of energy in the inducing body, but on the other hand its polarity is rather in- creased by the reaction of the induction. 5th. Magnetic, electrical, and chemical polarity are some- what similar in their general features, but differ considerably in their modes of manifestation. 6th. Bodies differ not only in their susceptibility to polarity, but also in their power of retaining it. Most atoms have an inherent chemical polarity which is more or less permanent and characteristic, although it may be increased, diminished, or entirely changed in quality, by induction. Chemism or chemical affinity is the manifestation of this polar energy acting between two differently polarized atoms. Every molecule may be regarded as naturally polarized, one part being positive while the other is negative. 45. Theory of the Galvanic Cell.—In order to bring the working of the cell clearly before the mind, let us assume the plates in Fig. 9 to be platinum and zinc, and the exciting fluid to be a solution of hydrochloric acid. The space between the plates may be con- sidered to be filled with molecules of the acid, each molecule composed of one atom of negative chlorine united to one atom of positive hydrogen. The negative chlorine atoms have an inherent tendency to com- bine with the positive zinc atoms, which are capable of taking a higher positive condition than hydrogen, and by this ten- dency the zinc atoms become strongly charged with positive electricity or posi- tive polarity, which they retain as long as they are in combination with the chlo- rine. By this means the rest of the zinc plate becomes negatively polarized or charged with negative electricity. Now, it is clear that if there is no chance for the plate to com- municate with the earth or some neutralizing body, it will soon Fig. 9. ELECTRICITY. 39 reach the maximum degree of polarity that can be induced by the chlorine. The action must then cease until the equilibrium of the polarity or electricity in the plate has been established; or, in our primitive cell, until the wires connecting the plates are brought in contact, when a neutralization takes place, and the action continues. Thus far, we have considered only the negative plate. When the chlorine atom? leave the hydrogen for the more positive zinc atoms, the hydrogen seizes upon the neighboring chlorine atoms in the adjoining molecules, and thus a stream of hydrogen atoms sets toward the platinum plate and are finally liberated at its surface. At this point two atoms combine to form a molecule of hydrogen ; but in order to do so, one of the atoms must discharge a part of its positive charge of electricity upon the platinum plate, thus charging it with positive electricity. By the above process, the zinc plate is rendered negative, or its electric tension is lowered below the normal by the withdrawal of positive electricity, while the platinum plate is actually charged above the normal, and is in a positive electrical condition. It is this difference of electrical state which causes a neutralization through the wires as long as the exciting fluid and the zinc plate last, or as long as the chemical action continues. If the wires are disconnected, the platinum plate soon becomes charged to a tension equal to that of the hydrogen atom3, and the zinc plate lowers its tension until the chlorine atoms will no longer leave the hydrogen to combine with it. The action then ceases until the connection is again made. The discharge is then continuous from the platinum to the zinc plate, and it can also be shown that a current passes through the liquid. Such is the best con- ception we possess of the simple galvanic cell which we have considered. 46. The Current or Circuit.—The circuit is said to be closed when the wires are connected, and there is a constant flow or transfer of force through the wires and through the liquid. It is said to be open or broken when the wires are separated so that the transfer of force ceases. If the wires from a galvanic cell or a collection of cells be connected with the earth instead of with each other, the current flows as if the latter were really done ; and it makes no difference how far apart the wires connect with the earth. This is called grounding the battery. No current actually flows from the one point to the other in the ground, but by bringing the plates in contact with the earth their electrical equilibrium is restored 40 MEDICAL CHEMISTRY. by it. This principle is made use of in telegraphy to avoid the necessity of a return wire. One of the wires of a battery situated at one of the stations is grounded ; while the other passes to and through the other station and is then grounded at that point; so that the current must pass between and through both stations to complete the circuit. 47. Electrical Tension or Electro-motor Force.— When we speak of the noimal electrical condition, we have reference to the electrical state of the earth or bodies in contact with it. The earth is the great storehouse of electricity, as the ocean is of water. If water is taken up from the ocean, and deposited upon the mountain side, it will run back to the sea in a stream, and can be made to do work, while reaching its former level, by turning a water wheel. The water, in other words, has acquired power to do work by its change of position, which in mechanics, is called its potential. In the galvanic cell, the equilibrium of the electricity is disturbed, and it acquires power to do work in returning to its former state of electrical equilib- rium. This property in electricity is called tension or elec- tro-motive force (E. M. F.). The strength of the E. M. F. will, of course, depend upon the difference in the electrical con- dition of the two plates. It is our purpose to consider here only such . practical points as we deem essential to the physician’s knowledge in the use of galvanic batteries. 48. Forms of Cells.—We have thus far discussed only one form of cell. The term battery, strictly speaking, is applied to a collection of cells; but it is frequently applied to a certain form of cell. Various kinds of cells are in common use. One difficulty in the working of the simple cell we have already described, is in the fact that the hydrogen accumulates on the platinum plate and prevents contact with the liquid, and thus obstructs the current. In order to obviate this, various means have been used to prevent this gas from reaching the platinum. In Grove’s cell, the platinum plate is suspended in a porous earthenware cup filled with strong nitric acid, and placed in the centre of the larger cup, containing the dilute sulphuric acid (1 to 12). The nitric acid oxidizes the hydrogen, converting it into water before it reaches the platinum. Bunsen’s cell is constructed in the same way as the above, except that the platinum is replaced with the cheaper gas retort carbon. In the working of the above cells the nitrous fumes evolved are ELECTRICITY. 41 very objectionable, and to avoid this, a solution of chromic acid in sulphuric acid, made by adding to 18 parts of water 4 parts of potassium bichromate and 4 of sulphuric acid, may be used. The chromic acid serves to destroy the hydrogen in the same way as the nitric acid, and no porous cup is needed. The elements used are zinc and carbon. This cell gives a strong current for a short time, and is one of the best in use, for medical purposes. The zinc plates are always removed from the liquid when the battery is not in use. Irnsome medical batteries a solu- tion of acid sulphate of mercury in water is used as the exciting fluid, instead of the above. In this case the plates are small, and made of zinc and carbon. The zinc combines with the sulphuric acid, and mercury instead of hydrogen is set free. Another form of battery is one in which the exciting fluid is dilute sulphuric acid and the elements zinc and silver, the latter being inclosed in a layer of chloride .of silver, which is intended to prevent the hydrogen from accumulating on the silver plate, by combining it with chlorine. 2AgCl -f- H2 = Ag2 -f- ‘2HC1. These cells are usually made in the form of long, narrow cylinders, so as to occupy a small space, and are very constant and effective. In the Leclanche cells, as usually constructed, the elements are a plate of carbon and a rod of zinc. The carbon plate is surrounded by a layer of peroxide of manganese, to serve as a depolarizing agent, or in a slightly different form, ferric oxide is used for the same purpose. The exciting fluid is a strong solution of ammonium chloride in water. This battery is one in very common use where an open circuit is to be used, is very constant, requires attention only at long intervals, and is inex- pensive. Various modifications of this cell have been proposed, but in efficiency they are not superior to it. The Callaud battery is constructed as follows: The elements are zinc and copper. The former is suspended in the upper por- tion of a solution of copper sulphate contained in a glass jar. The copper plate lies at the bottom of the jar, and the wire attached to it is covered with gutta percha for the purpose of insulating it. From time to time copper sulphate crystals are dropped into the jar, to keep up the supply. This battery is useful where a closed circuit is to be used, and the battery is to be in constant use. It is very constant when kept in good order, but has a low electro-motive force, and is seldom used in the construction of medical batteries. A new form of cell, which is said to give good results, is made as fol- lows : An iron tray or pot is nearly filled with a strong solution c* 42 MEDICAL CHEMISTRY. of ammonium chloride, and a plate of zinc is supported by non- conducting posts in this solution. A thin layer of oxide of copper is sprinkled over the bottom of the tray, to act as a de- polarizer. The wires are attached to the zinc and iron tray. When the oxide of copper becomes reduced, and loses its effect, it may be again oxidized by roasting it in the air. 49. Care of Batteries.—In order that a battery may per- form its work it will need some care in its management. All metallic connections, as well as the wires through which the current is to pass, must be of good conducting material. Copper or silver wire is usually employed for conductors, and where two wires are meant to connect, their surfaces must be bright and free from oxides, which are poor conductors. As far as possible, a uniform strength of exciting fluid should be maintained. In most batteries this will require entire renewal, from time to time, in order to supply new material for chemical action, and to re- move the products of former action. 50. Local Currents.—Owing to the imperfections in the zinc used in the construction of batteries, it is unequally acted upon by the liquid. The points where the zinc is harder, or contains iron, lead, or arsenic, act as negative plates to the rest of the zinc, and thus currents are set up between them which eat away the zinc, and cause a serious loss of material, as well as of force. “Amalgamation” of the zinc obviates this action by forming over the surface of the plate a homogeneous layer of zinc amalgam. To amalgamate the zincs, first wash them in dilute sulphuric acid (1 to 6), and then pour mercury upon them while still wet and rub in the drops until the whole surface is uniformly bright and smooth. It is well to keep a little mercury in the bottom of each cell, which keeps the plates amalgamated. A hissing sound, or the evolution of hydrogen from the surface of the zinc, is a sure sign that the zincs need re-amalgamating. 51. Polarity of the Elements of Batteries.—A serious hindrance to the working of batteries is what is called the polarization of the plates. We have already referred, when speaking of the construction of cells, to the accumulation of hydrogen on the carbon or platinum plate. When the current is of considerable strength, oxygen accumulates on the zinc plate and hydrogen on the opposite one. We then have a layer or plate of hydrogen against the carbon, and a layer or plate of oxygen against the zinc. The former of these is positive and the latter negative; and they are joined together by the same ELECTRICITY. 43 wires as the primary plates, as will be seen by a glance at Fig. 10. Not only is the liquid kept from perfect contact with the plates, but, owing to the action of the liquid upon these new gaseous plates, a current is developed in the opposite direction to that of the primary current, which may become so strong that it almost entirely overcomes the original current and destroys the efficiency of the battery. Some method must, therefore, be adopted to prevent the hydrogen from accumula- ting upon the carbon or platinum plate. Nitric or chromic acids, oxides of man- ganese, copper or iron, silver chloride, and copper sulphate are all used for this purpose, as referred to in article 48. 52. Secondary or Storage Batteries.—The polarity of the plates of a battery cell is utilized in the secondary or storage batteries. The cell contains two or more plates of large size, constructed of sheet lead, or finely divided lead pressed into plates, and is filled with dilute sulphuric acid. The plates are polarized by passing a current through the battery. The hydro- gen accumulates in or upon one plate, and the oxygen in the other, rin now disconnecting the charging battery, it is found that a current may be obtained from the polarized cell for some time, but in the direction opposed to that of the charging current. W hen the plates of this battery are once charged, they will remain charged for some weeks; and the current may be obtained at any time, whenever the wires from the opposite plates are connected. 53. Resistance of Conductors.—Conductors are bodies which allow a ready transmission of the electrical impulse through them, and are contrasted with another class of bodies called non- conductors or insulators. These terms are only relative, how- ever. Some bodies conduct electricity with great ease, while others offer more resistance to the passage of the current, or entirely refuse to allow an appreciable amount to pass. Even the best conductors offer some resistance to the passage of the current, f he metals are the best conductors, and of these silver is the best conductor known. Copper is second to silver only, and when both metals are pure the difference is but slight. If we compare wires of the same material, but of different Fig. 10. 44 MEDICAL CHEMISTRY. sizes and lengths, we find that the resistance of wires in- creases with the length, and diminishes with the area of the cross section. When a cell is in action, the current not only meets with resistance in the wires, but also in the liquid of the cell through which it has to pass. This last resistance is usually much greater than that of the wires, and is an important element in determining the strength and intensity of the current. 54. Ohm’s Law.—This law states that the intensity of a cur- rent developed by a battery will be equal to the electro-motive force divided by the resistance. By electro-motive force we mean the force with which the electric current is set in motion. This law may be stated algebraically as follows : C = where R represents the internal resistance of the liquid, r the external resistance or that offered by the wire, and E the electro- motive force, which is always the same when the same metals and exciting liquid are used. In any given form of battery, variations in the strength of the current must be due to the variations in resistance, either in the external or internal part of the circuit, or to a change in the strength of the exciting liquid, polarity of the plates, or secondary currents. We have already spoken of the resistance offered to the current by the polarity current, flowing in the opposite direction, and which may sometimes become almost as great as the electro motive force can overcome. It is clear that in order to increase the value of C, in our formula, we can increase E or diminish R and r. To increase the electro-motive force we select such metals and liquids as shall give us a relatively high intensity of current. We may increase the intensity of the E. M. F. by joining several cells, so that the force of the one may be reinforced by the next, and so on. This is done by connecting the zinc of the first to the carbon of the second, the zinc of the second to the carbon of the third, etc. Each cell added to the series adds to the current its E. M. F. diminished by its internal resistance; the external resistance being too small to be regarded. The formula applied to the series would be, when n equals the number of cells : C = —Now when the external resistance in the wire, r, is very small in comparsion with R, as when flowing through an ordinary copper wire, it may be disregarded ; and the equa- tion then becomes C = . That is, the effect of a battery of several elements in this case is no greater than that of a single cell. If, however, the external resistance, r, is great, as when the electrodes are applied to a human body, which has a resistance many times ELECTRICITY. 45 greater than the usual value of R, the value of C increases or diminishes very nearly in the same ratio as the number of cells. For medical purposes, therefore, we usually combine the cells as above described. Elements or cells so arranged, are said to be arranged in series, or arranged for intensity. We may also increase the value of C, in the formula above, by increasing the size of the plates, provided the external resist- ance is small. By so doing, we do not increase the electro-motive force, but we reduce the resistance in the cell by virtually com- bining several plates into one and increasing the surface exposed to the liquid, without increasing the distance through which the current has to pass in the liquid. Where a small resistance is to be overcome, therefore, large plates are to be preferred; or, which ft the same thing, all the zinc plates of the battery may Fig. 11. be connected, and all the carbon plates. When the cells are arranged in this manner, they are said to be arranged in multiple arc, or for quantity. The poles or electrodes °f a battery of cells are the conducting wires; that attached to the zinc plate is the cathode or negative electrode, and that attached to the platinum, carbon, or copper plate is the anode or positive pole. In electro-therapy the term electrode is often used to desig- nate the appliance fastened to the end of the wires for application to the patient, while the wires are called rheophores. 55. Induced Currents.—If a current of electricity, from a battery, be passed through one of two parallel wires A B (Fig. 11), lying near together, no current is observed in C D as long as 46 MEDICAL CHEMISTRY. the current in A B is constant; but if this be abruptly stopped, an instantaneous current is developed in C D, which we can de- monstrate by connecting the wire to a galvanometer (G). When we make the current pass from B to A, the current in the wire C D takes the direction from C to D; but on breaking the primary current, the induced current takes the direction I) to C. If, therefore, we rapidly make and break the primary or battery current by means of the key, K, we shall have a rapid to and fro current acting in the secondary wire C D. Now, if these wires be covered with silk or insulated, and are wound together around a spool or bobbin, the conditions of the experiment will remain unchanged, and we shall have the same phenomena in the coiled wires as if they were straight. Such a coil is known as an induction or Rhumkorff coil. The strength of the current Fig. 12. in the secondary wire, or the induced current, will depend upon the length of the wire acted upon, the strength of the battery or primary current, and the distance the wires are from each other. 56. Induction Coil.—It is customary, in constructing an in- duction coil, to make the primary coil of large, thick wire,so as to allow the battery current to pass with as little resistance as pos- sible, and to make the secondary coil of a much longer and thinner wire. The former is made into a smaller coil, which slips into the latter. Into the inner coil is pushed a bundle of soft iron wires which act as magnets when the battery current is sent through the coil. A small armature or piece-of soft iron fastened to a spring, vibrates before the end of the bundle of wires. When no current is passing the spring rests against the point of the screw Sc, Fig. 12. When a current is sent through ELECTRICITY. 47 from B to A, in the inner coil of wire, an induced current is pro- duced in the outer coil, from S to S', or from C to D. At the same instant the current B A magnetizes the core of wires O, and the hammer H is drawn towards them and away from the point of the screw. This breaks the current at that point, the core de-magnetizes, and the spring brings the hammer back to the screw, when the process is repeated, as long as the current from the battery E lasts. The induced current in S S' is, therefore, a to and fro current, or a make induced in one direction and a break induced in the opposite direction. This current is known as the Secondary, Induced, Inter- rupted or Faradic Current. The two wires a and b, Fig. 13, are connected with the primary coil, by the binding posts, and Fig. 13. carry the battery current. The wires c d are the terminal wires of the outer secondary coil, and carry the induced current. The interrupter is shown at g. 57. Extra Current.—It is very evident that each turn of the wire in the primary coil lies very close to and parallel "with the adjoining turns of the same wire, and that these con- secutive turns may be considered as constituting a series of parallel wires. In fact, every variation of the current in the wire ABF ig. 12 generates electro-motive force in the con- tiguous turns. An induced current is thus produced in the wire A B, which obeys the same laws as that induced in the independent wire, C D, and in the direction opposed to the 48 MEDICAL CHEMISTRY. battery current, when the latter is made or increased, and in the same direction when it is broken. This current is known as the primary induced or extra current. During the making or increasing of the battery current this extra cur- rent, acting against the battery current, retards or resists it, and hence is not felt at the poles P and P'. At the break this current goes in the opposite direction, and, as there is nothing to resist it, may be felt with its full force at P and P\ This current is therefore interrupted, and is felt only at the break of the battery current, and always in one direction. The primary induced, or extra current is feebler than the secondary, because the length of wTire acted upon is shorter. As we have just seen, the make extra current retards the battery current, so that it takes time for this current to attain its maximum force; and the make induced current is weakened in proportion to the longer time required. The secondary current developed at the time of making the battery current is therefore weak, and its physiological and chemical effects almost inappreciable. The break, secondary as well as primary, is developed with its full electro-motive force instantaneously, so to speak; hence, they alone have an appreciable effect when a resistance such as the human body is put into the circuit. 58. Influence of the Core.—When a galvanic current is sent through a coil of wire wound about a bar of soft iron, the bar becomes a magnet as long as the current passes, and loses its magnetism as soon as the current in the wire is broken. The effect of the bundle of soft iron wires is the same as that of a single bar. Moreover, when a magnet is suddenly made or destroyed, it causes a current to flow through the wire wound about it. The effect of the magnetic core is, then, only to retard the battery current when it is first passed through the coil, and to still further weaken the induced currents developed by it. Its sudden de-magnetization reinforces the break currents and makes them stronger. The currents are further modified by means of a draw tube made to inclose more or less of the pri- mary coil. When this is completely withdrawn the current is strongest; and when the inner coil is completely enclosed by it the currents are considerably weakened. Occasionally the sec- ondary coil is made to include any desired length of the primary, and thus the current may be varied at will. Figure 13 shows an induction coil with Grenet cell ready for use. 59. Magneto-Electricity.—Besides chemical action, other methods of producing electricity may be employed. We have ELECTRICITY. 49 already referred, in the last section, to the effect of suddenly making and destroying a magnet within a coil of wire. The same effect is produced when the magnet is made to approach or recede from the coil of wire, or when the magnet is increased and de- creased in strength. The simplest magneto-electric apparatus is composed of a strong horseshoe magnet, before the poles of which two short soft iron bars, called armatures, mounted on a shaft and wTound with coils of wire, are made to revolve by a crank. As the soft iron approaches the poles it becomes a mag- net and induces a current in the wire. As it recedes from the same pole the current in the wire is reversed, but by a pole changer it is made to pass from the instrument in the same direc- tion.* By multiplying the number of magnets and armatures, by using the current developed to strengthen the magnets, and by revolving the armatures at a high rate of speed, a very large amount of electricity may be produced. The electric light is now very generally supplied with electricity by machines made upon this principle and driven by steam or water power. Such Machines are called dynamo-electric machines. Small machines are sometimes employed for medical purposes, which have been improved by Mr. GaifFesoas to give much better results than the older forms of this apparatus. In these machines the electricity is the result of the conversion of mechanical force into electrical force, the two being mutually convertible. 60. Thermo-Electric Currents.—If two bars of dissimilar a b metals be soldered together at one end, thus: \/, and the junc- C fmn c be heated while the ends a and b are cool, electricity will pass; the direction of the current will depend upon the metals composing the couple. If the metals be bismuth and silver, the current will be from the former to the latter; if German silver |Md iron, the current will be from the former to the latter, -oy arranging a large number of such pairs in a pile, thus :— so that alternate junctions can be heated, a current of considerable strength may be produced. Such a pile may be constructed by arranging the bars in the form of rays around a hollow centre, in which a lamp or fire can be kept burning, and thus furnish a constant current of electricity, -thermo-electrical currents have not been used in therapy, but it f'1 ano^ler f°rin of the machine the coil of wire is on the magnet, and the current is produced by the variations in the magnet itself, caused oy the armatures. 50 MEDICAL CHEMISTRY. seems probable that a pile properly arranged may be made to furnish a current in every way equal to a galvanic current. 61. Frictional or Static Electricity.—When a dry glass rod or tube is rubbed briskly with a piece of dry flannel, silk, chamois leather, or cat’s fur, for a few seconds, it acquires the property of attracting light objects, as feathers, dust, or bits of paper to its surface, and is said to be electrified. Sealing wax, resins, gutta percha, etc., exhibit the same property to a greater or less extent. After the feather, or other light body, has adhered to the glass or seal- ing wax for a few seconds, it falls off; if the glass is now excited anew, and presented to the feather, it repels it. Or, if the feather be first made to repel from the glass, it will be found to be attracted by the seal- ing-wax with much greater force than before. From this it will be seen that there is a parallelism between this kind of electrical excitemenq and magnetism ; the excited glass and sealing wax bearing the same relation to each other as do the north and south poles of the magnet. Fig. 14. Machines for developing statical electricity are usually made of a glass disc mounted on a horizontal axle, and turned by a crank. Friction is caused by two rubbers, covered with amalgam, one on each side of the disc, regulated by a screw, and connected by a chain with the earth. The electrical condition of the glass plate is disturbed by the friction, and the positive electricity is removed from the plate by a row of small points connected with the prime conductor, and brought near the revolving plate. In the Holtz machine, which is the one now generally used, the rubbers are dispensed with, and the electricity developed by the induction of a body previously electrified. (See Fig. 14.) For ELECTRICITY. 51 a detailed description of this machine the student is referred to works on physics. Static electricity is capable of giving all the effects of galvanic or Faradic currents, when properly managed. It may also be used instead of the electric bath. 62. Physiological Effects of Electricity.—Electric cur- rents exert a marked physiological effect upon nerves, muscles, and the circulation of the human body, when they are made a part of the circuit. A constant or galvanic current has a re- freshing effect upon a nerve through which it is passed, as well as upon a muscle,.the latter being able to perform more work under its influence than without it. Under its influence the cir- culation of the blood may be increased in any part of the body, which lasts for some time after the electrodes have been with- drawn. The physiological effect of the negative pole seems to be greater than that of the positive. The interrupted, induced, °r Faradaic current stimulates nerves most wdien passed in the direction of the natural nerve current; this seems to be its prin- cipal physiological effect. For more extended remarks upon this part of the subject the student is referred to one or more of the manuals* upon the subject. 63. Chemical Effects of Electric Currents.—When a strong galvanic current is passed through a vessel of water con- taining a little sulphuric acid, the liquid is decomposed, hydrogen gas is given off at the negative pole, and oxygen at the positive. I his process is called electrolysis. If we perform the same experiment with a solution of a salt of one of the metals, the metal appears at the negative, and the negative element or radical appears at the positive pole. If the same current be passed through an animal tissue, the following changes take place : The water in the tissue is decomposed, the hydrogen appears at the negative pole, along with the metals of the salts, while the oxygen, with the non-metals or acid radicals, appear at the positive. The nascent oxygen surrounding the positive pole attacks the neighboring tissues and converts them into a hard eschar, while the alkalies at the other pole exercise their caustic properties and form a soft, frothy mass, containing hydrogen gas ln small bubbles. When a sufficiently strong and somewhat prolonged current is applied to the skin a similar effect to the above is produced at the point of contact of the electrodes. At the positive electrode the * De Watteville, Bartholow, or Beard and Rockwell. 52 MEDICAL CHEMrSTRY. skin first becomes red, with a burning sensation, then an eschar is produced with an acid reaction of the tissues. The eschar re- sembles that produced by a strong acid. At the negative elec- trode there is a vesicle formtd with an alkaline liquid ; if the ac- tion be prolonged more extensive ulceration takes place.* From this it will be seen that strong currents should be used with care. The effects of the magneto-electric current are very similar to if not identical with those of the galvanic current. Recently the use of frictional electricity in the treatment of disease has been revived and advised as a substitute for Faradic electricity. The effects of this form of electricity have not been so well studied as those of the Faradic and galvanic, but clinical results seem to indicate that its effects are even more pronounced than those of the latter. 64. Chemical Effects of the Galvanic Current Outside of the Body.—We have seen that when a current of electricity from a battery or a magneto-electric machine is passed through a solution of the salts of the metals, they are decomposed, the metal appearing at the negative, and the negative radical at the positive pole. The salts of some of the metals—the earths and alkalies—re- quire a very strong current, while some of the other metals do not require more than the current of one or two ordinary Le- clanch6 cups. If the current used be not too strong, the metal is deposited upon the negative electrode in a compact, tenacious form, adheres very firmly to the surface, and is capable of taking a polish. For this reason, the process of depositing metals upon the surface of other metals has come into extensive use in the arts of electro-plating and electrotyping. The principal metals used to deposit upon others, in this way, are gold, silver, copper and nickel. The objects to be attained are to protect easily oxidizable metals from rust, to preserve a brilliant surface, and to coat cheaper metals with the more valuable ones. This pro- cess is known as electro-plating. Only the outlines of these operations can be described here. 65. Electro-Metallurgy or Electro-plating.—Silver and copper are more easily deposited than most other metals. The strength of current needed to deposit these metals is rather feeble, unless the surface to be coated is large. The quantity of elec- tricity should be varied according to the surface to be coated; larger surfaces requiring a stronger current than smaller ones. * De Watteville, pp. 33 and 34. ELECTRICITY. 53 The strength of the solution of the metal to be deposited, will be governed somewhat by the material composing the article to be plated and the strength of the current, and will have to be de- termined experimentally by the beginner. When the proper strength of solution, current, etc., have been found, these should be kept as nearly constant as possible. The plating solution may be kept of constant strength by suspending from the positive pole of the battery a plate of the same metal contained in the solution, the size of which should be nearly equal to the size of the article to be plated. 66. Preparation of the Surface to be Coated.—The article to be plated must be thoroughly cleansed from rust and grease, and then, without handling with the fingers, suspended }n the solution, taking care that no bubbles of air are left cling- lng to its surface. It should be suspended from the negative pole (that coming from the zinc of the battery). To insure thorough cleansing, the article is to be polished as free as pos- sible from rust, dipped in dilute sulphuric or hydrochloric acid, thoroughly washed, and dipped into a solution of caustic soda, potash, or ammonia, to remove grease, again washed, and put i»to the plating fluid without drying or handling. The current ls immediately connected and allowed to pass for a few minutes, 0r until a complete coating has been deposited. The article is then removed and burnished with a soft brush and a little wliit- lng or precipitated chalk, thoroughly cleansed, and returned to the solution, and the deposition allowed to proceed with one or two repetitions of the burnishing process. In the case of silver, the labor of burnishing may be lessened somewhat by the addi- tion of 4 or 5 drops of bisulphide of carbon to each pint of the plating solution. 67. Preparation of the Solutions. —The composition of the solutions varies somewhat, according to the kind of surface to be plated. The Copper Solution used to deposit upon copper, brass, . ute metal, and all metals which are more electro-negative than itself (See Art. 86), is a solution of copper sulphate in water. it a more electro-positive metal, like iron, lead, or zinc is to be plated, the double cyanide of copper and potassium is to be used. a strip of clean iron be plunged into a solution of copper sulphate, a brown-red non-adherent deposit immediately takes place, without the aid of the current. It is therefore necessary to employ a solvent for the copper which shall have a different 1 elative affinity for the copper and iron from that which the acids 54 MEDICAL CHEMISTRY. have. Such a solution is the one mentioned. The solution may be prepared as follows : 1. Take a solution of copper sulphate, and add to it a solution of potassium cyanide or potassium ferro- cyanide until a precipitate ceases to form. Allow the precipitate to settle, and pour off the clear liquid. Add some water, allow it to settle, and again pour off! Repeat this process three or four times. Then pour upon the precipitate a solution of potass, cyanide (2 lbs. to 1 gal. water), until the precipitate dissolves; it is then ready for use. 2. Or, we may suspend the article to be plated (from a wire of ziuc?) in a solution made acid with tar- taric acid, and then made very strongly alkaline with an excess of sodium hydrate. Oubry first covers the iron with a layer of some substance which is impervious to acids. He then renders this layer conducting by rubbing it with graphite or plumbago. Results, good. Silver Solution.—The silver solution generally used is made as follows :— R. Potass, cyanide 4 oz. Silver cyanide oz. Water 1 gal. The Potass, cyanide is dissolved in the water, filtered, if not clear, and the silver cyanide stirred into the solution until it all dissolves. This solution contains 1 oz. of silver in the gallon. Another method : Dissolve a fifty-cent piece in dilute nitric acid. Add a solution of salt until it ceases to produce a precipitate. This precipitates the silver but leaves the copper of the coin in the solution. Now filter, pour off the liquid as described above in the preparation of the copper solution. The moist residue is now to be dissolved in a pint of water in which 1} oz. of potass, cyanide has been dissolved, when the solution is ready for use. All these solutions should be used at about the temperature of 70° to 80° F. Gold Solution.—This solution may be made as follows:— R. Potass, cyanide 2 oz. Gold cyanide 55 gr. Water 1 pint. The potass, cyanide should be quite pure. The solution should be used hot—from 130° to 150° F. The solution for plating with nickel, is made by dissolving the sulphate of nickel and ammo- nium in water, in quantity sufficient to give it a grass-green color. It requires a stronger current to deposit nickel and gold than the other metals mentioned. For further instructions in the preparation and use of electro-plating solutions the student is referred to a special work upon this subject. SOLUTION, DIFFUSION AND DIALYSIS. 55 SOLUTION, DIFFUSION AND DIALYSIS. . 68. Solution.—The power of water to dissolve substances is one of the most familiar of its properties. All liquids possess the same power to a greater or less extent; but liquids vary greatly in their solvent power, which is usually limited to a certain class of bodies. Thus, mercury will dissolve a number °t the metals ; alcohol is the proper solvent for the resins, ether tor the fats and some gums, and water for the ordinary metallic salts. Water is by far the most universal solvent, and for this reason it is commonly used as the medium of chemical changes. The solvent power of water varies greatly with different solids. '' hile some bodies absorb water from the air and become lique- fied, or deliquesce, others require several hundred times their weight of water to dissolve them, and some will not dissolve in Jt at all. Asa general rule, the solvent power of water for solids mcreases with the temperature; but there are a few exceptions to this rule. By the solubility of a substance, is meant the amount of the substance which will be taken up by the solvent. The solubility °f a substance is absolutely definite at a given temperature, and the amount which 100 parts of water will take has been deter- mined with every known substance. A knowledge of the solubility of ordinary solids is very im- portant to the medical student as well as to the chemist. The Jaw of compatibles is really the law of solubilities. A table ;vjll be found in the Appendix giving the approximate solubility °f those salts most commonly met with, and which the student should refer to whenever the question of solubility is spoken of. When a liquid has dissolved all of a solid that it can take up, is said to be saturated at that temperature ; but saturation 0 a liquid with one solid does not prevent it from dissolving others, and, in some cases, the solvent power of the liquid is thereby increased. When two or more salts are dissolved in a Jiqmd, an exchange of the metals and acids may take place, ac- to the laws of Berthelet, modified by the strength of the afrmities of the radicals present. 69. Solution of Gases.—Most liquids dissolve gases as well as solids. The quantity of a gas which 1 c.c. of any liquid will issolve, when the pressure of the gas upon it is 76 cm., is called |ts coefficient of absorption. As in solids, this coefficient must e determined by experiment for each gas ; but, as a rule, this ecreases as the temperature increases, although each gas obeys 56 MEDICAL CHEMISTRY. a rule of its own, which can be determined only by experiment. The volume of gas absorbed by a liquid at any given tempera- ture is the same, whatever the pressure. The quantity of gas dissolved, therefore, increases and decreases with the pressure. AVhen a liquid is exposed to a mixture of gases, it dissolves each in the same proportion as if it alone were present and exerting its own share of the total pressure. Thus when the air, a mix- ture of oxygen and nitrogen in the proportion of 1 to 4 respect- ively, is exposed to a mass of water, we find that the gases are absorbed by the water, in the proportion of 1 to 1.87 re- spectively. 70. Nature of Solution.—The term solution embraces two entirely different processes. The one a mechanical or phys- ical, and the other a chemical process. In physical solution the identity of the solid is preserved, as well as that of the water ; and by evaporation of the water we may obtain it again un- changed. In some cases there seems to be no manifestation of chemical action between the water and the solid; as when sugar dissolves in it. In other cases, which seem at first sight to be equally simple, there is heat developed, or heat absorbed, which, with other things, leads us to suppose that in these cases there is a true but feeble chemical union of the salt with the solvent. AVhen the solid separates again in crystals it takes a part or all of the water with it as water of crystallization. Sim- ple solution in water may be regarded, in some cases, as a mere overcoming of cohesion of the solid by the adhesion of the liquid to the solid ; while in others, it is a feeble combination of the solid with the water, and then the diffusion of this compound through the remaining water. The metallic alloys are in some cases mere mixtures, and in others they seem to be veritable compounds. When a metal dissolves in a dilute acid, there is, at first, a chemical action between the acid and metal, by which a soluble compound is formed. This then dissolves in the water present, as above described. This double process is sometimes termed chemical solution. 71. Diffusion of Liquids.—AVhen one liquid dissolves in another the process is called liquid diffusion. If upon the bottom of a vessel containing pure water, we pour some water colored with a little aniline red, by delivering it through a tube so as to prevent the mingling of the two, and then allow the vessel to remain at rest for some hours, the color will be found to have diffused itself throughout the water. If instead of a colored water we use a strong solution of com- CRYSTALLOGRAPHY. 57 mon salt, having a high specific gravity, we shall find by appro- priate tests that the salt has passed throughout the entire liquid. J'he rate of diffusion in these cases increases, for all substances, with the temperature. This is because the rapidity of motion of the molecules, to which we ascribe the phenomena of heat, in- creases with the temperature. 72. Dialysis.—If, in the experiment of the last section, we should interpose a porous partition of earthenware or parchment between the salt solution and the pure water, the result would be the same ; the salt would pass through the partition into the water. If, however, we use on one side of the partition a colloidal substance like gelatine or albumen, we shall find that almost none of this body passes through it into the water. Easily crystal lizable bodies pass through the membranes with ease, while those which do not crystallize—called colloids—pass with great difficulty. This property of bodies is made use of to separate the one class from the other. The process of the passage of liquids through porous membranes is called osmosis. The dialyser is an apparatus consisting of a shallow vessel pro- yided with a bottom of parchment or some porous membrane, into which the solution to be dialysed is placed, and the vessel is then floated upon pure water in a larger vessel. (See Fig. 15.) The volume of the water should be 8 or 10 times that of the solution to be dia- lysed. In the course of two or three days the prystalline bodies in the solution will be found m the water of the outer vessel, and the colloid bodies will be in the dialyser. Dial vsis is employed to prepare a pure colloid Material by dialysing from it all crystallizable salts. A complex mixture, like the contents of a stomach, is submitted to dialysis for the pur- pose of separating from it the crystalloids which it may contain, so as to get them in a pure watery solution for analysis. Re- cently a series of “ dialysates ” of the alkaloids have found their way into the market. These are the dialysed infusions of the crude drug. Fig. 15. CRYSTALLOGRAPHY. I 51.3 51.256 64 Yttrium. Yt. (V2)vm II. 4.8 92.5 89.816 + 65 Zinc. Zn. II. / 7 \D=32.5 65 64.904 + 66 Zirconium. Zr. II, IV. 4.1 89.5 89.367 + 66 THEORETICAL CHEMISTRY. The following named elements have been omitted from the above table, their identity not being yet thoroughly established :— NAME. O PQ S DQ QUANT1VALENCE. ATOMIC WEIGHT. 67 Decipium. Dp. II. 160 68 Holmium. Ho. 162 69 Ilmenium. 11. V. 105 70 Lavorsium. Lv. ? ? 71 Mosandiium. Ms. ? ? 72 Neptunium. Np. V. 118 73 Philipium. Pp. II, 74 74 Scandium. Sc. 11. 44 75 Thulium. Tm. 170 76 Ytterbium. Yb. 11. 173? 83. Molecular Weights.—Molecules, whether elemental or compound, must have a definite size and weight. The absolute weight of molecules and atoms is of no practical value to the chemist, but the comparative weights of molecules we shall find to be of vast importance. In weighing molecules we use the lightest known atom as the unit of weight. This atom is that of hydrogen. The relative weights of molecules have all been measured, and in expressing their weights our numbers express how many times heavier the molecule is than the hydrogen atom. Thus, the molecular weight of oxygen is 32. That is, the molecule of oxygen weighs as much as 32 atoms of hydrogen. Molecular weight, then, is the weight of a molecule as com- pared with the weight of the hydrogen atom. 84. Avogadro’s or Ampere’s Law.—This law was first enunciated by Avogadro, an Italian physicist, in 1811, and tvas reproduced by Ampere, a French physicist, in 1814. The law has already been stated (see chapter on gaseous state) as follows :— Equal volumes of all true gases, when at the same tempera- ture and under the same pressure, contain the same number of molecules. That is to say, a litre of any given gas, under the same conditions of temperature and pressure, always contains the same number of molecules, whatever the nature or composition of the molecules composing the gas. As a natural conclusion from this law, we have the following : First.—Gaseous mole- cules always occupy the same space , i. e., the molecule, together with the intervening space, always occupies the same volume. THE CHEMICAL ELEMENTS. 67 Second.—Since the same volume contains the same number of Molecules, it follows that the weights of equal volumes of any two gases (under like conditions as above), will be the weights of the same number of molecules. Hence, the two weights will stand in the same proportion to each other as the weights of their molecules. Thus, suppose equal volumes of hydrogen and oxygen gases, large enough to contain 10,000 molecules each; the weights of these gases will be in the one case 10,000 times the weight of one molecule of hydrogen, and in the other 10,000 times the weight of one molecule of oxygen, and these numbers must be to each other as the weight of 1 molecule of hydrogen to 1 molecule of oxygen. This law is the basis of many of our modern chemical notions. It is to chemistry what Newton’s law of gravi- tation was to the science of astronomy. This is not the place to enter mto the discussion of the proofs of this law. Suffice it to say, that it rests on about as strong proof as any other law of physics or chemistry, pr as the law of gravitation itself. As the present science of astronomy ls the living proof of the one, so the present science of chemistry is one combined proof of the other. 85. Number of Atoms in Elemental Molecules.—We may determine the number of atoms in many elemental mole- cules by a simple application of Avogadro’s law to well known experiments. This demonstration may be illustrated by reference to the behavior of the two gases, chlorine and hydrogen. Into a glass tube inverted over mercury, put equal volumes of the two gases, and allow the apparatus to stand in diffuse light. After some hours, the greenish color of the mixture will have entirely disappeared, the gases having combined to form the colorless hydrochloric acid. The mercury stands at the same height in the tube as at the beginning of the experiment. The volume of the hydrochloric acid is therefore just equal to the volume of both constituents. -bet the following diagram represent this combination :— y- H Cl H Cl 1000 1000 A 2000 . Since the volume of the hydrogen and that of the chlorine are equal, 's clear, from the law, that the number of molecules of each will be the same ; also, the number of molecules of the hydrochloric acid gas must be equal to the sum of the molecules of the two gases used. Sup- pose, for illustration, that the volume of hydrogen taken contained 1000 molecules ; then there will be 1000 molecules of chlorine, and 2000 mole- cules ol hydrochloric acid, the volume of this gas being twice that of 68 THEORETICAL CHEMISTRY. hydrogen. Each of the 2000 molecules of .hydrochloric acid must con- tain an atom of hydrogen and one of chlorine ; hence, 2000 atoms of each of these elements have been derived from 1000 molecules of the same, and therefore each molecule must have furnished two atoms. Experiments quite as decisive have been made to show that in water, the 2 volumes of hydrogen and 1 volume of oxygen pro- duce only 2 volumes of water-vapor. Thus :— V H H 0 H2 O 1000 A 2000 By the same reasoning we may show that eacli molecule of oxygen contains two atoms; also, that each molecule of water must contain two atoms of hydrogen to one of oxygen, instead of one, as formerly taught. Most of the molecules of elementary substances contain two atoms ; or, in other words, are diatomic. Mercury, cadmium, zinc, and barium, however, contain but one atom in each mole- cule. Oxygen, as ozone, contains three atoms. Phosphorus and arsenic contain four atoms. Sulphur at lower temperatures contains six, while at higher temperatures it contains only two. Some molecules which at ordinary temperatures contain two atoms in their molecules, break up or dissociate, as it is termed, at very high temperatures. Thus chlorine, bromine, and iodine, which at a moderate heat are diatomic, at a very high temperature, 800 C., begin to dissociate, and become monatomic at the strongest furnace heat. Many compounds do the same thing, (Hg2 Cl2, N202,N204). The law of Ampere is, there- fore, true only at moderate temperatures. 86. Molecular Weight, Determined by the Law of Avogadro.—It has just been shown that the molecule of hydrogen is composed of two atoms. We have already de- fined molecular weight, as the weight of a molecule in units of hydrogen atoms. It may also be defined as the sum of the weights of its constituent atoms. The molecular weight of hydrogen is therefore 1 + 1, or 2. Suppose, for example, we weigh equal volumes of hydrogen and oxygen gases under like conditions of temperature and pressure, and find the weights to be respectively 1 and 16 grammes. It follows that the molecules of these gases are to each other as 1 to 16, for, according to the law, each contains the same number of molecules. As the mole- cular weight of hydrogen has been shown to be 2, it follows that the molecular weight of oxygen must be 32, for 32 bears the 2000 PROPERTIES OF ATOMS. 69 same ratio to 2, that 16 does to 1. 1 : 16 :: 2 : 32. From this it will be seen that the molecular weight of oxygen is twice its density, or its specific gravity as compared with hydrogen. The same reasoning applies to all other gases, whether elemental or compound, and we may state this fact as follows: The mole- cular weight of any body is twice its density in the state of gas. The converse of this statement is also true, viz.: fhe density of a gas is one-half its molecular weight. PROPERTIES OF ATOMS. 87. Definition.—An atom is the smallest conceivable portion of matter. It is the smallest portion of an element that can enter into the formation of a molecule, or take part in a chemical re- action. The student should strive to clearly comprehend the difference between a molecule and an atom. The former is a collection of the latter held together by an attraction called chemism or chem- Jcal affinity. Molecules are destructible; they may be broken pp and their properties destroyed. The atom, on the other hand, Js an indestructible solid particle, whose properties, so far as we know, are never destroyed. As to the properties of molecules, we conceive that they have size, weight, form, color, etc. 88. Atomic Weight.—Atoms differ from one another in their weight, and the quality and the quantity of their combin- mg power. Further than this we have no certain knowledge of their properties. The weight of an atom of any given element is always the same. In weighing atoms we do not take the absolute weight, but the relative weight, using the hydrogen atom as the unit. Idle atomic weight of any element expresses the number of tunes its atom is heavier than the atom of hydrogen. The atomic height of oxygen is 16; i. e., the atom weighs 16 times as much ns the atom of hydrogen. The atomic weights of the elements will be found in the table, Art. 82. 89. Quality of Combining Power.—Polarity of the Atoms.—We have seen (Art. 64) that when a current of elec- tricity is sent through a solution of a metallic salt, the metal collects about the negative electrode, while the non-metallic part °f the salt appears at the positive. Most metallic compounds are capable of decomposition by electrolysis, and the molecule seems to be divided into two parts; one of which is attracted to the positive and the other to the 70 THEORETICAL CHEMISTRY negative electrode. We have seen (Art. 44) that two bodies, similarly polarized, repel each other, while bodies oppositely polarized attract each other. We conclude, therefore, that those atoms which are attracted by the negative pole of the galvanic current are positively polarized, while the others are negatively polarized. This is what is meant by the difference in the quality of combining power. Positive and negative, as applied to the polarity of atoms, is not absolute but relative; and the polarity of an atom may be changed, by the inducing action of another atom, from positive to negative, or vice versa. As a general rule, the metallic atoms are positive, and the non-metallic negative. When several atoms are brought into contact with each other, those having similar polarity repel one another, as do other bodies that are of like polarity, while those having differing polarity attract one another ; hence, union or combination can only take place between atoms that are unlike in their electric quality. In the following table the elements are so placed that each one is electro-negative to those below, and electro-positive to those above it. Negative End —. Oxygen. Sulphur. Nitrogen. Fluorine. Chlorine. Bromine. Iodine. Selenium. Phosphorus. Arsenic. Clirt mium. Vanadium. Molybdenum. Tungsten. Boron. Carbon. Antimony. Tellurium. Tantalum. Columbium. Titanium. Negative End —. Silicon. Hydrogen. Gold. Osmium. Iridium. Platinum. Rhodium. Ruthenium. Palladium. Mercury. Silver. Copper. Uranium. Bismuth. Tin. Indium. Lead. Cadmium. Thallium. Cobalt. Nickel. ELECTRO-CHEMICAL SERIES. Negative End - Iron. Zinc. Manganese. Lanthanum. Didymium. Cerium. Thorium. Zirconium. Aluminum. Erbium. Yttrium. Glucinum. Magnesium. Calcium. Strontium. Barium. Lithium. Sodium. Potassium. Rubidium. Cassium. Positive End -f. Positive End +. Positive End +, 90. Quantity of Combining Power.—By an analysis of a large number of compounds of hydrogen with other elements, it has been found that while chlorine combines with it in the pro- CHEMICAL NOTATION. 71 portion of its atomic weight, i.e., 1 part of hydrogen to 35.5 parts of Cl, Oxygen combines with 2 parts of H to 16 of 0, Nitrogen “ “ 3 “ of H to 14 of N, Carbon “ “ 4 “ “ “ 12 “ C, and so on; so that the power of the atoms to attract and com- bine with hydrogen are not alike. This is expressed by saying that the equivalence, or quantivalence, of the atom in question is 2, 3, 4, 5, 6 or 7, according as it will attach to itself, be ex- changed for, or take the place in a molecule, of 1, 2, 3, 4, 5, 6, 7, atoms of hydrogen, or their equivalent. The chemical equivalent of an atom, is an atom which can take Jts place in a molecule. Atoms are divided into monads, dyads, triads, tetrads, pentads, hexads, or heptads, according as they can fix 1, 2, 3, 4, 5, 6 or 7 atoms of hydrogen, or their equivalent. A monad is equivalent to a monad. “ dyad “ “ to 2 monads. triad “ “ to 3 “ or 1 monad and 1 dyad, tetrad “ “ to 4 “ 2 dyads, or 1 monad and 1 triad. A pentad “ “ to 5 “ a tetrad and 1 monad, a triad and 2 monads, or 2 dyads and 1 monad. The equivalence of an atom is often indicated to the eye by dashes, thus:— Monad O— Dyad —O— Triad —O— rp I \ I / \./ \ I / Tetrad —U— Pentad O Hexad •—O— Heptad —O— I / \ / \ / \ It will be seen that the hydrogen atom is the unit of comparison 111 combining powers or equivalences, and the dashes represent the number of bonds or points of attraction, or poles of the atomic magnet. The equivalence of an atom may also be expressed by a Roman numeral placed above and to the right, thus:—-H1, O11, Cl111, CIV, etc. Univalent,bivalent, trivalent, etc., ar.e adjectives sometimes used as synonymous with monad, dyad, triad, etc. Jl- Symbols and Formulae.—In representing atoms and Molecules to the eye, we make use of a series of symbols derived rom the names of the elements themselves. This is usually the inltial letter of the English or Latin name, or in case two or CHEMICAL NOTATION. 72 THEORETICAL CHEMISTRY. more names begin with the same letter, the initial with some other characteristic letter. Thus, on reference to the table in Art. 82, we have B, Ba, Bi, Br, representing the atoms of boron, bari- um, bismuth and bromine respectively. In this book, a symbol is never used to represent the element in general, but a symbol always represents an atom, with all its properties, and nothing else. Formulae.—A formula is the sign of a molecule. It there- fore, represents a definite weight—the molecular weight; and in the case of gases, always the same volume. Formulae are made up of symbols, as a molecule is made up of atoms; and the atoms composing a molecule are all represented by symbols in the formula. Thus: HC1 is a formula representing a molecule containing one atom or 1 part of hydrogen, and one atom or 35.5 parts of chlorine. In writing formulae, we write the symbols composing the mole- cule in juxtaposition, beginning with the more electro-positive. Thus: KOC1, HBr, etc. Multiplication of Molecules and Atoms.—When we wish to represent more than one atom, we use a small numeral at the right hand lower corner; thus, 02, represents 2 atoms of oxygen, or, since the molecule of oxygen contains two atoms, this also represents the molecule. As4 represents 4 atoms of arsenic, or since the molecule of arsenic contains four atoms, it is also the formula of a molecule of arsenic. When we wish to represent more than one molecule of a substance, we use full- sized numerals placed before the formula. Thus, 2H20 represents two molecules, each of which is com- posed of two atoms of hydrogen and one of oxygen. Or, we may inclose the formula in a parenthesis, and place a small numeral at the right hand lower corner, thus : (H20)2. Ex- amples :— H2S04 represents 1 molecule, containing 2 atoms of hydrogen, 1 of sulphur, and 4 of oxygen. 5H2S04 represents 5 molecules of the same substance. 3NB4N03 represents 3 molecules, containing in each molecule two atoms of nitrogen, 4 atoms of hydrogen, and 3 atoms of oxygen; 27 atoms in all. 2K2A12(S04)4 represents two molecules, containing in each molecule 2 atoms of potassium, 2 atoms of aluminium,* 4 atoms of sulphur, and 16 atoms of oxygen; 48 atoms in all. As the symbols always represent the atomic weights, we may reduce any formula to figures, or find its molecular weight, by adding together the weights of the symbols composing it. Let it be desired to find the molecular weight of H2SG4. By refer- ence to the table in Art. 82, it will be seen that H., = 2, S = 32 CHEMICAL NOTATION. 73 and 04 = 4 X 16 = 64. By adding together these three numbers we obtain 98, the weight of the molecule. An empirical for- mula is one which merely gives the kind and number of the atoms composing a molecule. A rational or graphic formula amis to show the arrangement of the atoms in the molecule, with relation to one another. Examples of empirical formulse :— HN03, H2S04, CuS04 Na2C03. Rational formulae for the same :— H—O iv—'0 U -M=0 H—0 o =0 II-0— © =0 p — 0 q =0 Lu—0— =Q Na 0 q Na_0_c—C. Rational formulae are useful in giving us a more definite con- ception of the relations of the atoms to one another in the mole- cule. They have served as the guides in some of the most im- portant chemical discoveries of the present century; such as the discovery of the process of manufacturing artificial madder and *ndigo from coal tar products, by synthesis. 92. Variation in Quantivalence.—By graphic formulae We are able to explain a fact that is always a matter of difficulty to the student, viz.: the variation of equivalence of atoms. There are two well known series of salts of mercury and copper, in which there is no real variation ; hut, owing to the Uniting of two atoms of the metals, each loses an available bond 0r point of attraction. The following formulae will render this clear:— Hg-C1 g-Cl and Hg—Cl. I Hg—Cl. pi Cu ri ~~U and Cu—Cl. | Cu—Cl. In other cases, and under certain well known conditions which We can control in the laboratory, the atom which has previously existed as a dyad, suddenly becomes a tetrad, or a triad becomes a pentad, and so on. -These changes are always extremely puzzling to the student, and wre shall dwell a little upon them. AVhen ammonia gas 0r instance, (NH:t), is absorbed by water, it combines with a of the water and becomes NH4OH. If we represent he two molecules graphically, we have, H H—0—yr—H. H-hl and As will be seen, two new points of attraction have made their 74 THEORETICAL CHEMISTRY. appearance upon the nitrogen atom. A large number of such cases are known, and the explanation is as follows :— The full quantivalence, or atomicity of nitrogen, is pentad. In the compound H:iN, for some unknown reason, two poles of the atomic magnet neutralize each other, and so the combining power of the atom is lessened by two. This increase or diminu- tion of combining power always takes place in pairs, so that a dyad may become a tetrad, but not a triad. A monad may be- come a triad or a pentad but never a dyad or tetrad. 93. Other Signs used in Writing.—A plus sign between two formulae indicates that the substances, whose molecules they represent, are brought together. The minus sign indicates that the molecule following it is abstracted from the preceding one. The sign of equality is used to indicate that what follows, is the result of some change that has taken place. HCl+AgN03 = HNO:j -j- AgCl shows that the molecules represented by the first two formulae have been brought together, and that a change has taken place resulting in the formation of the last two. 94. Compound Radicals.—A radical or root of a series of compounds, is a characteristic atom or group running through all of them, like a root in language. Thus, the interrogative root runs through all that class of words, as who, which, when, what, etc. So, in chemical compounds we have a large number of potassium compounds, in which the atom K appears as the charac- teristic atom: As KNO:!, IvC103, K2C03, K2S04 and KC1. It is therefore called the root or radical of these compounds. A single atom, which forms a series of characteristic compounds, is called a simple radical. Sometimes, instead of being a single atom, it is a group of atoms that is found to be the characteristic of a series of com- pounds. Thus, we have: (NH4)N03, (NH4)C1, (NH4)N02, (NHt)2S, etc., in which the characteristic radical is a group of atoms, or is a compound radical. A compound radical may be regarded as a group of atoms which behaves like a simple radical, or single atom. Like the single atom it only exists in combination with another atom or group of atoms; for its bonds or points of attraction are not satisfied unless it be in combination. Compound radicals, like atoms, may be positive or negative. Each compound radical has a definite equivalence like the atoms. Some of them have re- ceived arbitrary names which do not express their composition, and in most cases end in yl. Thus, (PO)'", phosphoryl, CHEMICAL NOTATION. 75 (H-0-)' hydroxyl, (CO)" carbonyl, (CH3)' methyl, (C2H5)' ethyl, (H4N)' ammonium, (CN)' cyanogen, (NH2)' amidogen-. The last three are exceptions to the rule as to the ending. In writing the formula of these compound radicals, they may regarded for the time as atoms of a compound nature. If We wish to represent that several similar compound radicals enter into the same molecule, we inclose the formula in a paren- thesis, and use the numerals as with atoms, thus, (NH4)2C03, Fe,(OH)„ In the following table will be found the more important elements arranged according to both quality and quantity of combining power. The elements at the top of the table are negative to all below them; and those at the bottom are positive to all above. They are also divided into monad, dyad, triad, etc., some appearing in two or even three columns, because of their change quantivalence. In the second table will be found the more common compound radicals, with the names of the classes of com- pounds they form, arranged, as far as possible, in the same order as the elements. In regard to their electrical order, much less certainty exists than with the elements. QUANTIYALENCE OF THE ELEMENTS. Monads. Dyads. Triads. Tetrads. Pentads. Hexad. fluorine ... F Chlorine ... Cl Bromine ... Br iodine Oxygen 0 Sulphur S Nitrogen. N Sulphur S Nitrogen... N Sulphur.... S PliosphorusP Phosphorus P Arsenic... As Arsenic As Chromium Cr Boron B Antimony Sb Carbon c MauganeseMn Silicon Si Hydrogen.. H Gold Au Platinum Pt Bismuth. Bi Tin Sn Silver a g Mercury... Ilg Copper Cu Iron Chromium.... Fe Cr Lead Pb Cadmium .. Cd Cobalt Co Nickel Ni Iron Fe Chromium. Cr Manganese... Mn' Manganese Mn Zinc Zn Magnesium M g Calcium.... Ca Strontium.. Sr Aluminum... A1 I0?'11™ Ha 1 otassium. K Barium Ba 76 MEDICAL CHEMISTRY. Compound Radicals with Names op Compounds they form. Monad. Dyad. Triads. Tetrads. N03=Nitrates Cl 03=ChIorates N02=Nitrites Cl 0=Hypochlorites PH2Oj=Hypopliosphites CN=Cyanides S04=Sulphates Cr 04—Chromates Cr2 07=Bicliromates S03=Sulphites CO 3=Carbonates C2O4=0xalates r04=Phosphates S03=Borates As 03=Arsenites As 04=Arsenates Si 04=Silicates P„07—Pyrophosphates Fe Cy6=Ferroc}anides C0II50 7=Citrates ■ Hexads. C7H602=Ben/.oates C6 H 60=Carbolates C3H„03=Lactates NH4=Ammonium CII3=Methyl C2H3=Ethyl C4H405=Malates C7H403=Salicylates Hg2=Mercurous Salts Cu2*=Cuprous Salts Fe2Cy j 2=FerricyanideB Al2=Aluminic Salts Cr2=Chromic “ Mija=-Manganic “ Fe2=Ferric “ COMPOUND MOLECULES. 95. Compound Molecules Classified.—The system of nomenclature now in use for naming chemical compounds, is based upon the composition and properties of the bodies in question; and the name of a body is intended to express our idea of its chemical composition. Homogeneous bodies are supposed to be made up of a collection of similar molecules ; hence a formula which represents the composition of a single molecule, really represents the composition of the mass. In applying names to compounds, we apply the name to the molecule as well as to the mass. Compound bodies may be divided into two classes: 1st. Those whose molecule is composed of two kinds of atoms or radicals, called binary compounds, and 2d, those whose molecules are composed of three or more kinds of atoms or radicals, called ter- nary molecules. Examples: NaCl, KBr, MgCl2, and (NH4)C1 are examples of binary molecules. KC103, K2S04, CaC03, (NH4)N03 and Ba(N03)2 are examples of ternary molecules. Acids, Bases and Salts.—Ternary molecules are divided into acids, bases, and neutrals or salts. An acid is a substance which usually possesses a sour taste, corrodes the metals with the evolution of hydrogen and the formation of salts, changes blue vegetable colors to reds, and neutralizes the caustic properties of alkalies by forming salts with them. All acids contain hydrogen, which can be replaced, by a metal. This hydrogen is united to the remaining portion of the mole- cule, either directly, as in binary acids, or by a linking atom, usually oxygen, as represented by the following graphic formula;: COMPOUND MOLECULES. 77 H-Cl, gzg>4 H 0 N iTq. The replaceable hydrogen of an acid is called basic hy- drogen, and the number of such atoms determines the basicity °f the acid. A dibasic acid, for example, is one containing two ntoms of basic hydrogen ; a tri-basic acid three, a tetra-basic acid t°ur, and so on. When the linking atom in these ternary acids 18 oxygen', the name of ox-acids is applied to them. The term Sulpho-acids is applied to those containing linking sulphur. A base has properties which in many respects are opposed to, and neutralize the effects of acids. They restore the vegetable blue colors reddened by acids, they neutralize the sour taste, they react upon acids to form salts, with the elimination of one or ®ore molecules of water. The strong bases have a caustic ac- tion upon the tissues, decomposing the fats, with which they form soaps. A base may be defined, as a compound whose molecule is com- posed of a positive atom, or group of atoms, united by linking. °xygen to hydrogen. The positive atom is, in most cases, me- tallic. As: —0—H Ba—0—H, n —OH 0a—OH, /O—H Bi—0—H \0—H /OH Fe—OH I \OH I /OH Fe—OH \OH 9 w T o i ffl K-O-H, In the last formula we have an example of a compound radi- Cal united to H by O. The bases are named hydrates.* A salt molecule is composed of a positive radical united by inking oxygen to a negative radical. The radicals, in this case, as in acids and bases, may be either simple or compound. Thus: K—0—Cl, K—0—N02, Na2=02=C0 Ba=02=S02(NH4)—0—N()3. It is evident, also, that a salt may be formed by treating an acid uh a metal which replaces the hydrogen of the acid with Metallic atoms. Zn -f- H2 - Oa = S02=Zn = 02 = S02 + HH. It may be regarded, then, as an acid whose replaceable hy- * The above definition applies only to inorganic bases. 78 MEDICAL CHEMISTRY. drogen atoms have been replaced by positive atoms or radicals. In a dibasic acid, like H—0\q /O it is possible to replace one H—0/ \0, of the atoms of hydrogen and leave the other undisturbed. We thus have, for example, H—0\Q/0 which exhibits the prop- K—0/te\0, erties, and answers to the definition of both a salt and an acid. It has acid properties by virtue of the replaceable hydrogen, and saline properties by virtue of the other chain in which the K has replaced H. Such a body is called an acid salt, while the salts first men- tioned, in which all the II atoms have been replaced by positive atoms, are called normal salts. Double salts are formed by replacing a part of the hydrogen of the acid by one positive radical, and a part by another. KNaS04 from hhso4, Mg<0-P0 " 4—0/ from H—0\ H—0—P“0 H—0/ If a base or metallic oxide be treated with sufficient acid to neutralize it, a neutral salt is usually formed ; but if the base or oxide be much in excess of what the acid would require to expel all its hydrogen, a basic salt will in some cases be formed, according to the following formulse:— Pbco m=0 /0-fC2H,0) Pb—0-Pb-0-(C2H30) NOMENCLATURE. 79 NOMENCLATURE. 96. Naming of Chemical Compounds.—Rule.—Give the name of the positive radical first; then the name °f the leading negative atom or radical with its termi- nation changed to ide, in binaries, and to ite or ate in ternaries ; ite denoting the lower, and ate the higher quantivalence of the negative atom. EXAMPLES. Na Cl = Sodium Chloride, — binary. Na N02= “ Nitrite, — ternary. NaNOs— “ Nitrate, — “ Ba Cl2 = Barium Chloride, — binary. Ca Br2 =. Calcium Bromide,— “ Ba SO 3 = Barium Sulphite — ternary. Ba S04 = “ Sulphate,— “ As will be seen on inspection, the equivalence of the negative atom is indicated by the comparative amounts of oxygen which ]t holds. Compare BaSO;j and BaS04; also NaN02 and NaNO;!. jn compounds like the following—SnCl2, SnCl4, CuCl2, Cu2Cl2, 2, Hg2Cl2, FeCl2 and Fe2Cl6-—where more than one quantiv- alence of the positive atom is known, the endings ous and ic are used to distinguish them ; thus :— SnCl2 = Stannous Chloride, dyad tin. SnCl4 —Stannic “ tetrad tin. CuCl2 = Cupric “ Cu2Cl2 = Cuprous “ Hg2Cl 2 — Mercurous “ HgCl2 = Mercuric “ PeCl2 = Ferrous “ dyad iron. Fe2Cl6 = Ferric “ tetrad iron. Where more than two quantivalences are known, we‘employ the prefix per to denote a quantivalence higher than that denoted l)y ic or ate, and hypo to denote a lower than that denoted by °us or ite. They are affixed alike to positive and negative. N20 = Nitrous oxide. N202 = Nitric “ N204 = Nitric peroxide or tetroxide. Na2S203 = Sodium Hyposulphite. H2S03 = Hydrogen Sulphite or Sulphurous acid. H2S04 = “ Sulphate or Sulphuric acid. KCIO = Potass. Hypochlorite. HC102 = Hydrogen Chlorite or Chlorous acid. HC10S — 11 Chlorate or Chloric acid. KC104 = Potass. Perchlorate. C120 = Hypochlorous oxide. EXAMPLES. 80 MEDICAL CHEMISTRY. The class of bodies which we have called acids are more com- monly named in the following manner:— The negative atom, with the prefixes and suffixes usually attached to the positive element, is named first; this is followed by the word acid, thus:— HCl = Hydrogen Chloride or Hydrochloric acid. HBr = “ Bromide or Hydrobromic “ HI = “ Iodide or Hydroiodic “ H2S — “ Sulphide or Hydrosulphuric acid The binary compounds, above mentioned, are called hydracids to distinguish them from the oxacids or ternary acids; and in the naming of these acids the prefix hydro is used. EXAMPLES OF OXACIDS. HCIO — Hydrogen, Hypochlorite or Hypochlorous acid. HN02 = “ Nitrite “ Nitrous “ HCIO3 — “ Chlorate “ Chloric “ HN03 = “ Nitrate “ Nitric “ H2S03 = “ Sulphite “ Sulphurous “ H2S04 = “ Sulphate “ Sulphuric “ H2C03= “ Carbonate “ Carbonic “ It will be seen that each of the above acids has a characteristic negative group of atoms; thus in sulphates we may always ex- pect the group SO/'. In a sulphite we will always find the group SO/'; in a nitrate NO/ ; in a chlorate CIO/, etc. Nomenclature Simplified:—The above rules of nomen- clature may be applied much more easily by the student, by reference to the table given in Art. 94. By the use of this table, the student can easily learn to name all the more common compounds. Let it be desired, for example, to name the following formula: Cu S04. Cu is the symbol for copper. We next look among the compound radicals and find S04 to be the characteristic group of atoms found in all sulphates. The name of the formula is, therefore, copper sulphate. What is the formula of zinc carbonate? We find zinc among the dyads, as also the group CO:), opposite the word carbonates. Both these radicals are dyad, and as a dyad is equiva- lent to a dyad, they will combine directly, and we shall have Zn C03 as the desired formula. What is the formula of sodium sulphate? The symbol of sodium is Na ; it is monad, while S04 is dyad. Two monads are equivalent to one dyad. Hence Na2S04 is the formula of sodium sulphate. Let it be desired to know the formula of calcium phosphate. Here we wish to combine a triad and a dyad. To NOMENCLATURE. 81 do so, we must double the triad to get an even number of bonds; and then we must take three atoms of calcium to get six bonds. The formula will thus be Ca3(P04)2. What is the formula of Ferric Oxide ? In ferric iron two atoms always go together as a hexad. It will require three dyads to saturate the hexad, and we have Fe20:!, or for the hydrate Fe2(0-H)6, or Fe2Clfi for the chloride. Stannous chloride will have the formula SnCl2, while stannic chloride will be SnCl4. Mercuric oxide will be HgO, but mercurous oxide will be Hg20. Cuprous chloride = Cu2Cl2. Examples for Practice.—We introduce here a series of examples for practice in nomenclature, with corresponding names in columns below. The numbers opposite the formulae will be found opposite the corresponding names below. 1 Ba02H2 2 CaC201 3 BiCl, 4 Na2C03 6MgS04 - ® Fe2(S04)3 7 AgN03 8 (NH4)C1 9 HN03 10 Hg2Cl2 11 PbCr04 12 KI 13 K20 !4 As203 1" Barium Hydrate. 2 Calcium Oxalate. 3 Bismuth Chloride. - 4 Sodium Carbonate. 5 Magnesium Sulphate 6 Ferric Sulphate. 7 Silver Nitrate. 8 Ammonium Chloride 9 Hydrogen Nitrate. 1A (Nitric Acid). 10 Mercurous Chloride. 11 Lead Chromate. 12 Potassium Iodide. 13 Potassium Oxide. 14 Arsenious Oxide. 15 Cu2FeCy6 16 (NH4)2S ! 17 As2S3 ! 18 NH4MgP04 19 KHC03 i 20 SbCI3. i 21 BiON03 : 22 Fe3(Pe2Cy12) 1 23 K(CN)S 1 24 K2Cr04 i 25 Fe2(Cr04)3 S 26 Al2(OH)6 27 KCy. 28 ZnO 15 Copper Ferrocyan- ide. ! 16 Ammonium Sulphide 17 Arsenious Sulphide. 18 Ammon. Magnesium i. Phosphate. 19 Potassium Hydrogen Carbonate or Potass- Bicarbonate. 20 Antimonous Chlo- e ride. 21 Bismuth Oxy-nitrate. 22 Ferrous Ferricya- nide. 23 Potassium Sulpho- I oyanate. i 24 Potassium Chromate.' 25 Ferric Chromate. 26 Aluminic Hydrate. 27 Potassium Cyanide. ‘ 28 Zinc Oxide. 29 SrC03 30 Sr(N03)2 31 BaCl2 32 NH4N03 33 (NH4)2C03 34 KNaS04 85 NaHCOs 36 Ca3(P04)2 87 Ca(P02H2)2 38 NaCIO 39 Bi203 40 02 41 KC104 42 Pb-OCC.H.O^H 29 Strontium Carbonate 30 Strontium Nitrate. 31 Barium Chloride. 32 Ammon. Nitrate. 33 Ammon. Carbonate. 34 Potassium Sod. Sul- . phate. 35 Sodium Hydrogen Carbonate. 36 Tri-Calcium Phos- phate. 37 Calcium Hypophos- phite. 38 SodiumHypochlorite 39 Bismuth Oxide. 40 Oxygen. 41 Potassium Perchlor- ate. 42 Basic Plumbic Ace- tate. 82 THEORETICAL CHEMISTRY. 97. Irregularities in Nomenclature.—In many medical and pharmaceutical works, the old style of making the negative precede the positive, with the preposition of between them, is used. In this case per is used instead of ic or ate, and proto instead of ite or ous. EXAMPLES. NEW NAME. OLD NAME. SnCl2 = Stannous Chloride or Protochloride of tin. SnCl4 = Stannic “ or Perchloride of tin. Fe2Cl6 = Ferric “ or Perchloride of iron. Fe2(S04)3 = “ Sulphate or Persulphate of iron. Fe203 = “ Oxide, or Per-or Sesquioxide of iron. Hg2I2 = Mercurous Iodide or Protiodide of mercury. Hg2Cl2 = “ Chloride or Protochloride, mild chloride, or calomel. HgCl2 — Mercuric chloride or Bichloride, corrosive sublimate. HgO = Mercuric oxide or Bed oxide of mercury. Eg20 — Mercurous oxide or Black oxide of “ Protoxide of “ The proto-salts of iron are the ferrous salts, while the per salts are the ferric salts. The names of the oxides of the alkaline metals, the earths, and.alkaline earths are sometimes named as follows :— A1203 Alumina. MgO Magnesia. BaO Baryta. SrO Strontia. CaO Lime. K20 Potassa or Potash. Na20 Soda. Some writers name those oxides of the non-metallic elements which dissolve in water to form • acids, as though they were formed from the acids by abstracting one or more molecules of water. Thus SO 2 is named Sulphurous Anhydride. C02 “ “ Carbonic ' “ N208 “ “ Nitrous N205 “ “ Nitric “ P205 “ “ Phosphoric “ For, S02 -f- H20 = H2S03 = Sulphurous acid. CO2 -j- H20 = H2C03 = Carbonic “ N205 + H20= 2HN03 = Nitric “ • P205+3H20= 2H3P04= Phosphoric “ S03 + H20 = H2S04 = Sulphuric “ It is a common custom with some authors to use the numerals di, tri or ter, tetra and penta, to indicate the number of atojns of the element to whose name the numeral is prefixed. NOMENCLATURE 83 NEW NAME. OLD NAJtE. Thus:—FeS2 Ferric Disulphide or Bisulphide of Iron. Fe2S Diferrous Sulphide or Sulphide of Iron. Fe2S3 Ferric Sulphide or Sesquisulphide of Iron. FeS Ferrous Sulphide or Protosulphide of Iron. CO2 Carbon Dioxide or Carbonic Acid. PC13 Phosphorus Taoxide, PCI 5 Pentoxide, Hg Cl 2 Mercuric Dichloride, Bichloride of Mercury. A few compounds are known by names which do not express their composition. Thus:—H3N Ammonia. GN Cyanogen (symbol Cy). H3Sb Antimoniuretted Hydrogen or Stibine. H3As Arseniuretted ♦ “ or Arsine. H2S Sulphuretted “ or Hydrosulphuric Acid. H3P Phosphuretted “ or Phosphine. H4C Light Carburetted ‘‘ or Marsh Gas. H4C2 Heavy Carburetted “ or Olefiant Gas. A glossary of obsolete and popular names, and those of some chemical compounds occasionally met with, will be found in the Appendix. 98. Chemical Reactions and Equations.—All material bodies, under certain conditions, may undergo marked changes ln properties. As the physical properties of bodies depend upon the properties of their molecules, any great change in these properties must depend upon a corresponding change in the molecules. In a homogeneous mass of matter, all molecules are ; and any chemical, change which we are able to produce Jn one molecule of such a mass, may, with certainty, be produced jn all. Hence, by representing the changes which take place between two dissimilar molecules, we may, in reality, represent the changes taking place between the masses of which these molecules form a part. It is upon this principle that we repre- sent chemical changes to the eye. When two substances, on being brought together, act upon each other, the mutual action between them is called a reaction. A body which is added to another to cause such a change, is called a reagent. When a jet of coal gas is burned in the air, the reagents are the gas and the oxygen of the air. The results of the reaction are light and heat. The products of the reaction, are the watery vapor and carbon dioxide which are produced. I he factors entering into the reaction, are oxygen and the com- pounds which compose the gas. 84 THEORETICAL CHEMISTRY. While all material molecules are more or less liable to undergo chemical change by the action of external agencies, some do so very readily, while others resist such changes with "considerable force. Chemical reactions are favored by anything that lessens cohesion, or favors the free movement of the molecules; as solu- tion, pulverization, trituration, heat, light and electricity. Reaction between solids is always slow, and, in many cases, entirely wanting. If the solids are brought together in solution, the reaction takes place with readiness; if volatilized, still more readily. Reactions between gases usually take place almost'in- stantaneously throughout the mass, and in many cases, with an ex- plosion. Heat usually favors chemical action, and cold retards it. Light favors many kinds of chemical change, but does not affect all. Reactions, in the laboratory, are generally conducted in solutions. When the bodies are soluble in water, that liquid is generally selected; if not, some other solvent, such as ether, alcohol, chloroform, etc., may be employed. When two or more substances are brought together in solutioft, the action that will tak,e place depends largely upon the following conditions, first formulated by Berthelet, and usually known as the Laws of Berthelet:— 1st. When two or more substances are brought together in solution, if by any rearrangement of the atoms a product can be formed which is insoluble in the liquid present, that substance will form and separate as a precipitate. 2d. When two substances are brought together in solution, if a gaseous body, or one volatile at the temperature of the experi- ment, can form, it will form and escape as a gas or vapor. Illustration.—BaCl2 + Na2S04 = ? By a rearrangement of these atoms, according to the principles stated in preceding articles, there can only form BaS04 and 2NaCl. The latter of these is soluble in water, while the former is not; hence, BaS04 would always separate from this mixture. Zn + 2HC1 = ZnCl2 -j- H2. Here,' by. changing the places of the two positives, hydrogen is set free, and escapes. As matter is indestructible, it follows that there can be neither ioss nor gain in the weight of the matter taking part in a reaction. The sum of the weights of the factors entering into a reaction must, therefore, be equal to the sum of the weights of the pro- ducts coming from it. Hence, if we place the sum of the formulae of the factors equal to the sum of the formulae of the products of any reaction, it must always form a true equation. In writing out representations of chemical reactions, the student should re- member the following rules:— NOMENCLATURE. 85 1st. Positives combine with negatives and not with posi- tives. 2d. Every member of the equation must represent a whole molecule, or a number of molecules. 3d. The quantivalences of the atoms, and radicals must all be saturated according to the rules laid down in article 96. 4th. An acid and a base cannot exist in the same solution. They are incompatibles, and neutralize each other. 5th. The strongest acid generally selects the strongest base, except in cases where this is modified by Berthelet’s laws. Compound radicals, as a rule, remain as such in the products. To write chemical equations, place the formulae of the factors, connected by a plus sign, equal to the formulae of the products, also connected by a plus sign. Now take such a number of molecules as factors that only whole molecules can be produced in the products. EXAMPLES. + — 4" —7 Ag N03 + Na Cl = (?) Silver Nitrate. Sodium Chloride. We first determine which are positive and which are negative radicals. Ine metals are positive (Art. 89), and the non-metallic radicals are nega- te, as indicated by signs above the symbols. We next cause the positive radicals to exchange places, whence we have Ag Cl.and Na NOs. On referring to the table of quantivalence (Art. 94), we find all these radicals to be monad, and therefore chemical equivalents. Ihe completed equation will, therefore, be— Ag NO, + Na Cl = Ag Cl + Na N03 Silver Nitrate. Sodium Chloride. Silver Chloride. Sodium Nitrate. Complete the following-: 1. 2Ag (NOa) + H2S — ? 2. Pb (N03)2 + H2S = 3. H2 (S04) + Ca02 H2 = 4. KI + Ag N03 = 5. Fe Cl2 + 2KOH = 6. Fe2 Cl6 + 6KOH = 7. Ni N03 + Na2S = 8. Mg S04 + (NHJ OH = 9. Ba Cl2 + Na2 S04 = 10. Bi Cl, rf H20 ;= Bi OC1 + ? 11. Pb (C2H302)2 -p H2 S04 = . 12. CaCl2 + (NH4)2 Cr04 13. Na2 C03 + 2HC1 = 14. Cu S04 + NaOH = 15. Hg2 (N03)2 + NaCl =r 16. Mg S04 + H Na2P04 + NH40H 86 THEORETICAL CHEMISTRY. 99. Stochiometry.—Chemical symbols represent definite weights, or atomic'weights. Chemical formulae, therefore, enable us to calculate the percentage of any ingredient in the compounds they represent; or, from chemical equations, we may calculate the weight of any substance required by any given process, or the exact amounts evolved by it. These calculations are all based upon the atomic weights. Molecular weights are derived from the atomic weights. The molecular weight of calcium carbonate, Ca COs, is (C = 12) + (03 = 48) + (Ca = 40) = 100. (See Table, Art. 82.) On inspection, we see that x%°7 of the whole quantity are calcium, j carbon and xVtj oxygen. Let it be desired to calculate the quantity of hydrogen in one part of water; formula H20. (H2 = 2) + (O = 16) = 18 T\ = Hydrogen, ff = Oxygen. Stated in the form of a proportion, this would be 18 : 2 :: 1 : X2X = In this proportion, the fourth term must bear the same relation to the third, that the second does to the first. Stated in this way, the first problem would be as follows: Ca C03 : Ca : : 1 : x = 100 : 40 : : 1 : x = y = 40 or 40 per cent. In other words, calcium carbonate contains 40 per cent- of calcium. The same calculation may be made for oxygen, as follows: Ca C03 + 03 : : 1 x = 48 or 48 per cent. 100 -j- 48 :: 1 x = 48 or 48 per cent. If, instead of one part, we desire the amount in ten parts, we substitute 10 for one in the third term of the equatiou, thus: 100 : 48 : : 10 : 4.8 parts. The fourth term of such an equation must always be of the same de- nomination as the third. From the above, we easily deduce the following rule for the statement of such problems: As the formula of the substance given is to the formula of the substance required, so is the weight of the substance given to x the weight of the substance required. Reduce the formulae to their nu- merical equivalents,.and find the value of x. When three terms of an equation are given, the fourth may be found by multiplying the two means (second and third' terms), and dividing the product by the given extreme. In calculating the per cent, of any ingredient, by the above rule, the weight given is understood to be 100, i. e. per cent, is parts per hundred. Calculations based upon a reaction may be illustrated as follows:—• NOMENCLATURE. 87 Problem.—How much sulphate of zinc can be prepared from .10 gramrnes of zinc ? Reaction.—Zn -f- H2S04 = ZnS04 -f- H2 Statement.—Zn : ZnS04 : : 10 : x Numerical Statement.—65 : 65 32 -f- 64 — 161 : 10 : x Solution.—161 X 10 = 1610 h- 65 = 24.8 Ans. in grammes. Problem.—How much Na NO, will be required to make one pound ofHNOa? Equation.—Na NO 3 + H2S04=NaHS04 + HNOs The only terms of this equation concerned in the problem are NaNOa and HN03 ; the latter being the substance given. Statement.—H N03 : NaNOs : : 1 : x pounds. Numerical Statement.—63 h- 85 : : 1 : x Solution.— .1 X 85 = 85 -j- 63 = 1.35 pounds. PART III. INORGANIC CHEMISTRY. 100. Classification of the Elements.—For convenience of study, some system of classification of the elements is necessary. Many systems of classification have been proposed, but all are open to criticism; yet, >ve may adopt one of these with the un- derstanding that the classification is largely an arbitrary one, and serves merely for convenience. Berzelius wras the first to divide the elements into two great classes, to which he gave the names metals and metalloids. The metals are those elements which possess more or less lustre and opacity, readily conduct heat and electricity, and are electro-positive in combinations. The non-metals, or metalloids, are such as are gaseous ; or, if solid, have no lustre, ductility or malleability, are poor conductors of heat and electricity, and are electro-negative in combinations. This division, while it serves a general purpose, is not capable of exact application; for there are a number of the elements which are positive in one combination and negative in another. Iodine and arsenic, which most chemists regard as metalloids, have a decided lustre, and the latter forms alloys by fusion with the metals; indeed, there is no line of demarcation, between these two classes, which can be regarded as fixed. Some classification is necessary, which is not based upon the physical properties alone, but upon their chemical properties; a classification which brings together those elements which have similar chemical properties, and similar compounds with other elements; thus enabling the student to better associate the facts °f each in his mind. There are two important chemical characters upon which most attempts at classification of the elements into groups are based ; viz: quantivalence, and electrical polarity of the atoms. By a consideration of both of these properties, the elements may be grouped so as to bring similar elements together. The behavior of the oxides of the elements with v7ater, may be taken as an index of their polarity. Electro-negatives dissolve m water and form acids, while electro-positives form bases, and some again play a neutral or double role. I he most convenient classification of the elements is the one 90 INORGANIC CHEMISTRY. that will bring together into groups those most nearly, related in chemical properties. For this purpose the quantivalence and electro-chemical properties will be employed in this book, with the exception of the two elementary gases, oxygen and hydrogen. These two elements are taken out of their groups and studied separately, owing to their importance among the elements, and their typical character. The following division of the more important elements seems to be best adapted to the wants of the student:— THE NON-METALLIC ELEMENTS. Group I. Hydrogen and Oxygen. Group II. The Chlorine Group, or the Negative Mo- nads. Fluorine, Chlorine, Bromine, Iodine. Group III. The Sulphur Group, or Negative Dyads. Oxygen (by some authors), Sulphur, Selenium, Tellurium. Group IV. The Nitrogen Group, or the Negative Triads. . Nitrogen, Phosphorus, Arsenic, Antimony, Bismuth. Group V. Boron. Group VI. The Carbon Group, or Negative Tetrads. Carbon, Silicon. THE METALS. Group I. The Alkaline Metals. Lithium, Sodium, Potassium, Rubidium, Csesium and Ammonium. Group II. The Alkaline Earths, Calcium, Strontium, Barium. Group III. The Magnesium Group. Magnesium, Zinc, Cadmium. Group iV. The Iron Group. Chromium, Manganese, Iron. Group V. Nickel Group. Nickel, Cobalt. Group VI. Lead. Group VII. Copper, Mercury. - Group VIII. Silver, Gold. Group IX. Glucinium, Aluminium, Gallium, Indium. Group X. The Platinum Metals. Platinum, Palladium, Rhodium, Ruthenium, Iridium. Group XI. Molybdenum, Osmium, Tungsten. HYDROGEN. 91 TYPICAL ELEMENTS. HYDROGEN. Symbol, H. Atomic weight, 1. Molecular weight, 2. Density, 1. Weight ' of one litre = 1 crith = .0896 grms. Quantivalenee, Monad. 101. Occurrence.—Hydrogen occurs in a free state in the gases from volcanoes, fumeroles of Iceland and Tuscany, and in the atmosphere of the sun; in combination, it exists in water, and in most organic substances of both animal and vegetable origin. It is a necessary constituent of all acids and ammoniacal compounds. 102. Preparation.—Hydrogen may be prepared— First.—By the decomposition of water, by a strong electric current, which splits the water up into hydrogen and oxygen ; the former appearing at the negative and the latter at the positive pole. Second.—By decomposing water by certain metals. When sodium or potassium is used, the decomposition takes place in the cold; but with iron and some other metals at a red heat. Na2 + 2H20 = 2NaH0 -f H2 3Fe2 + 8H20 = 2Fe304 + 8H2 Third.—By the decomposition of the mineral acids with some metal, as zinc, iron, or magnesium. In this case, the metal takes the place of the hydrogen, which is crowded out of the molecule the acid. Zn -J- H2SO4 = ZnS04 -f- H2 Water is added to dissolve the zinc sulphate formed, and to prevent it from crystallizing on the surface of the zinc. Chemi- cally pUre zjnC) however, will not dissolve in very dilute acid, unless it be made one pole of a galvanic couple. -This method is the one usually employed for the preparation °f hydrogen in the laboratory. The gas prepared from com- mercial zinc and acid is not pure, however, as it contains other 92 INORGANIC CHEMISTRY. gases derived from impurities in the materials used. Pure hydrogen, in small quantities, may be prepared by the first method, or by decomposing water with an alloy of sodium and mercury—sodium amalgam. 103. Properties.—When pure, at ordinary temperatures and pressures, hydrogen is a colorless, transparent, odorless, tasteless gas. It is 14i times lighter than air, being the lightest gas known. One litre of it at 0°C. and 760 mm. pressure, weighs .0896 grams. = the crith. It is almost insoluble in alcohol, and at a temperature of — 140°C and under a pressure of 650 atmospheres, it has been condensed to a steel-blue liquid. It is the best con- ductor of electricity and heat among the gases. It is very diffusible, and a vessel to contain it, must be made of glass or some very compact material. Certain metals absorb large quan- tities of it. Palladium will absorb 900 times its volume of the gas: spongy platinum, sodium, potassium and iron also absorb considerable quantities of it. This action of the inetals is called occlusion. During the condensation of the gas in the pores of the metal, the latter is heated to. a considerable degree. A jet of hydrogen may be ignited by directing it upon a ball of finely divided platinum, or a ball of asbestos, which has .been dipped into a solution of platinum chloride, and heated in the flame of a lamp. Under ordinary conditions, hydrogen has little tendency to unite with the other elements, chlorine being the only one with which it combines directly, and then only under the influence of light. At higher temperatures it unites with oxygen, and is, there- fore, readily combustible in the air, burning with a bluish and very hot flame. The product of the combustion is watery vapor. A given weight of hydrogen produces more heat in burning than any other known combustible. It will not maintain animal respi- ration, but is not poisonous. A lighted taper is extinguished on being thrust into it. If hydrogen and oxygen be mixed together and a lighted taper applied to them, an explosion takes place. On examination, it will be found that the hydrogen has com- bined with one-half its volume of oxygen, and if there be present more than this quantity of the latter gas, it will remain undis- turbed. If, on the other hand, there be less than one-half as much oxygen as hydrogen, there will remain a part of the hydrogen. In other words, when these gases conibine they do so only in the one proportion. This law holds good with all chem- ical combinations, and is known as the law of definite propor- HYDROGEN. 93 tions. Hydrogen has so much of a tendency to unite with °xygen at high temperatures, that it will take it from many me- tallic oxides, and leave the metal in the free state. This process is called reduction or deoxidation. It is by this process that the reduced iron or iron by hydrogen of pharmacy is produced. Hydrogen will unite quite readily with some elements which !t ordinarily does not affect, if they be put into the flask where the hydrogen is generating. Arsenic and antimony compounds, for example, are split up, and these elements unite with the hy- drogen. Many oxides are reduced, and chlorine is removed from chlorides under these circumstances. The greater energy of the hydrogen, in these cases, is explained by the supposition that at the moment of liberation of the hydrogen atoms, and before they have combined into molecules, they are ready to take up with any atom with which they may come in contact, and are stronger m their affinities, before combining with a neighboring hydrogen atom, by just the force it will take to decompose the hydrogen molecule when once -formed. This condition of an element is known as the nascent state (from nascere, to be born). When any chemical action takes place between molecules, there ls a considerable expenditure of force required to break up the combinations already formed, before new ones can be formed; and when these combinations do not exist, the new combinations fake place with ease. Hydrogen is one of the constituents of the gases of the stomach and intestines, and is frequently found jn the gases exhaled from the lungs. Its physiological properties, u any, are slight. In its chemical properties, hydrogen resembles the metals more than the metalloids, usually playing the positive role, and forming salts in which it occupies the place of metallic atoms in similar compounds, and is easily substituted for them, or displaced by them. On this ground, the acids may be regarded as salts of hydrogen. 104. Uses.—The uses of hydrogen are limited. Owing to its dghtness, it is sometimes used to fill balloons. The ascensional power, or the lifting power, of one litre of hydrogen, is found by deducting its weight, .0896 grms., from the weight of one litre of air, 1.2932 grammes, or 1.2036. The lifting power of one cubic oot is about 525 grains, or 1 ounce and 55 grains. Hydrogen also used with oxygen in the oxy-hydrogen blowpipe. In the aboratory, it is used as a reducing agent. 94 INORGANIC CHEMISTRY. OXYGEN. Symbol, O. Atomic’weight, 16. Molecular weight, 32. Density, 10. Weight one litre, 1.4=3 grammes. 105. Occurrence.—Oxygen was discovered by Priestley, in 1774, in the air, of which it constitutes 20.6 per cent. It ex- ists in the air in the free or uncombined state, mixed with nitrogen and small quantities of other gases. It enters into the composition of a great variety of compound bodies, such as min- erals, vegetable and animal bodies. Water is eight-ninths, sand one-half, and alumina one-third oxygen, by weight. 106. Preparation.-—Oxygen may be prepared :— First.—By heating mercuric oxide in a retort or flask, when it breaks up into oxygen and black mercurous oxide; or, if the temperature be high, into oxygen and metallic mercury. 2HgO = 2Hg + 02. Second.—By heating black manganic oxide (Mn02) to redness, in an iron or clay retort, when it gives off a part of its oxygen. 3Mn02 = Mn304 + 02. Third.—By decomposing acidulated water with a current of electricity. The oxygen obtained in this way is- very pure, but it is too slow for ordinary use. Fourth.—The best method, and the one generally employed, is by heating potassium chlorate. 2KC103 =2KCl + 302- The evolution of the gas takes place more regularly and at a lower temperature, if the chlorate be mixed with ferric oxide, cupric oxide, or manganic dioxide. In practice, the last is gen- erally used in the proportion of one part of the oxide to two or three parts by weight of the chlorate. The manner in which the oxide acts is somewhat obscure, for it seems to undergo no change in composition, and is found to be unaltered in the resi- due left in the retort. The process may be conducted in a round-bottom glass flask, furnished with a large-size delivery tube, provided that the heat is carefully regulated and not allowed to become too high. One kilogramme of the chlorate ought to yield about 140 litres of oxygen. 107. Properties.—Oxygen, when pure, is a colorless, trans- parent, odorless, tasteless gas, slightly heavier than air. ’ Its sp. gr. is 1.10563. Water dissolves three per cent, of its volume, OXYGEN. 95 at ordinary temperatures. Under a pressure of 300 atmospheres, at a temperature of —140°C, it condenses to a transparent liquid whose specific gravity is 0.9787 (Pictet). It is magnetic, f he magnetism of the atmospheric oxygen is equal to that of a layer of iron covering the surface of the earth 0.1 millimetre in thickness. Oxygen forms oxides of all the known elements except fluo- rine. Its range of affinities, and its energy of combining power are its characteristic chemical properties. Most elements com- bine directly with it, especially at high temperatures. When this oxidation is accompanied by light and heat it is called combustion. A body is said to be combustible when it unites readily with oxygen, and liberates light and heat in so doing. A combustible body usually requires to be heated to a more or le'ss elevated temperature before it will be acted upon by the oxygen; but when the process has once begun it is kept up by the heat generated in burning. Some bodies, not usually regarded as combustible, will burn when heated to a red heat and plunged into an atmosphere of pure oxygen; as, for example, a steel watch spring or small iron wire, so treated, will burn with great brilliancy. 'Bodies which burn in air with difficulty, burn in pure oxygen with great read- iness. Oxygen is the great supporter of combustion, but the action of oxygen and the combustible body are mutual. A jet of air may be burned in a jar of illuminating gas or hydro- gen as readily as these last burn in the air. Oxidation often takes place slowly, and the heat produced, although the same in both cases, passes off into the air or surrounding bodies, so that the temperature does not rise much above that of the air.’ This ls sometimes termed slow combustion ; or, more commonly, oxidation. Most ordinary combustibles contain carbon and hydrogen, and in such cases the results of the process are carbonic dioxide and watery vapor. In case the combustible contains sulphur, ft becomes sulphurous oxide; if nitrogen, it becomes either ammonia or free nitrogen, according as the oxidation is complete or incomplete. The respiration of animals is very similar to combustion. 108. Uses.—The uses of oxygen are very many. The oxygen taken into the air vesicles of the lungs passes through their thin walls, by diffusion, into the blood. There it combines with the haemoglobin and circulates with it throughout the body, assist- ing in burning up the waste products of the broken down tissues. 96 INORGANIC CHEMISTRY. One hundred volumes of arterial blood from a dog contain twenty-two volumes of oxygen (Grehaut), and this quantity varies with the amount of lisemoglobin, or with the red globules. In the air, the oxygen is mixed with nitrogen to dilute it and regulate its action. Oxygen is of use as a supporter of combus- tion, to afford us artificial heat and light. With this heat we drive our steam engines, warm our houses, smelt our ores and cook our food. 109. Ozone.—If a series of electric sparks be passed, for a few minutes, through a portion of air or oxygen gas confined in a tube, it acquires a peculiar pungent odor, and exhibits properties which it did not previously possess. The same odor is usually detected in the air in the neighborhood of a frictional electrical machine while in operation; or in the gas given off by a mixture of potassium permanganate and sulphuric acid ; or when phosphorus, partially covered with water, is exposed to the air and allowed to undergo slow oxidation; or by the- electrolysis of water containing sulphuric and chromic acids. Ozone can often be detected about a galvanic battery, using as the exciting fluid a solution of sulphuric acid and potassium bichromate. Ozone has not been prepared in the pure state. The highest degree of concentration reached does not exceed one per cent. 110. Properties.—The properties of ozone are those of oxygen, intensified. It is a very powerful oxidizing agent, tarn- ishes silver and mercury, sets iodine free from potassium iodide, and is readily destroyed by contact with easily oxidizable organic matters, and by a temperature of 260°C. In this last case, it is reconverted into oxygen. It is a strong bleaching agent. It is soluble in oil of turpentine and in ether. In preparing ozone from oxygen, a contraction takes place, and it again expands on being reconverted into ordinary oxygen. This shows that it is a condensed form of oxygen. Ozone is times heavier than oxygen, and its molecule is represented by /0\ ~ O r-0 or °3- 111. Tests.—The presence of ozone may be detected by its action upon a paper saturated with a solution of potassium iodide and boiled starch paste. This paper becomes blue by its action, owing to the liberation of iodine, which gives a blue color with starch. A piece of reddened litmus paper saturated with potass, iodide is also blued. A paper moistened with an alcoholic solution of guaiaeum is also changed to a light blue by its HYDROGEN AND OXYGEN. 97 action. A piece of paper impregnated with a solution of man- ganous sulphate or lead hydrate turns dark brown or black in its presence. These reactions disappear when the air is heated to 260°C. (500°F.). Ozone is found in the air, especially after thunder storms, and when in appreciable quantities acts as a purifier of the air, destroying, by its oxidizing action, many forms of organized germs hurtful to animal and vegetable life. On this account, it has been regarded as a valuable antiseptic and disinfectant. As it is very irritating to the mucous mem- branes, and when present to any considerable extent causes distressing coryza or even haemoptysis, it is to be recommended "with caution. HYDROGEN AND OXYGEN. Two compounds of these elements are known. Hydrogen oxide, or water, H20. Hydrogen "peroxide, or oxygenated water, H202. HYDROGEN OXIDE, OR WATER. 112. Occurrence.—"Water is so widely distributed in nature, that it is almost universal. It exists in the three states of solid, liquid, and gas or vapor. It occurs in the solid form, below the temperature of 0°C. (32°F.), and as liquid between 0°C. and 100°C. (212°F.). In the form of vapor it exists in the air at ordinary temperatures. It is poured into it from combustion, in various manufacturing processes, from volcanoes, by spontaneous evaporation from the surface of the ground, bodies of water, and leaves of foli- age* Seven-eighths of the entire human body is water. Pota- toes contain 75 per cent.; water-melons, 94 per cent, and cu- cumbers 97 per cent, of water. It enters into the composition of ffiany rocks, and forms a necessary part of many crystals, where 1t is known as water of crystallization. 113. Composition.—The composition of water may be de- termined in two ways: by analysis or by synthesis. If a current of electricity be conducted through a vessel of water, slightly acidulated with sulphuric acid, the water will be de- composed into the two gases, hydrogen and oxygen, in the pro- portion of two volumes of the first to one of the second. If, now, these gases be mixed together in the same proportion, and an electric spark sent through a portion of the mixture, they recom- bine with an explosion. If equal volumes of the two gases be 98 INORGANIC CHEMISTRY. used, there will remain, after the explosion, one-fourth as much gas as was taken, which, on testing, will he found to be oxygen. These two experiments show that the proportion of the gases, by volume, must be two of hydrogen to one of oxygen. On weighing the two gases, we find that the oxygen weighs eight times as much as the hydrogen ; or, by weight, water is composed of | oxygen and i hydrogen. The recombination is conducted in the endiometer of the con- struction represented by Fig. 3l and the decomposition in the Fig. 30. Fig. 31. apparatus shown in Fig. 30. For the synthesis of the water, the mixed gases are inserted into the graduated limb through the stop-cock at the top. The wires connected with a small induction coil, are connected with the two platinum wires soldered into the glass just below this stop-cock, and which are separated within the tube by a space about tV of an inch. On connecting the coil with the wires from the battery a spark is sent across the space between the platinum wires, which ignites the gases. In Fig. 30 the wires are seen to pass through the tubes and terminate in two HYDROGEN AND OXYGEN. 99 strips of platinum foil, from which the gases escape to the top of their respective limbs. If the graduated limb in Fig. 31, con- taining the gases to be combined, be surrounded by a larger tube through which steam from a kettle is kept passing, and the gases are measured before and after the explosion, at the same tempera- ture, it will be found that the steam produced by the combination of the oxygen and hydrogen, will occupy two-thirds of the vol- ume of the mixed gases before the- explosion. That is, the two volumes of hydrogen and the one volume of oxygen have formed two volumes of steam or vapor of water. Applying the law of Avogadro, it will be seen that there-are the same number of Molecules of water produced as there were of hydrogen taken. Now, as we have seen in Part II of this book, the hydrogen Molecule contains two atoms, and hence the molecule of water must contain two atoms of hydrogen. By the same reasoning, it may be shown that the molecule contains but one atom of oxygen ; °r, the formula is H20. 114. Preparation.—Water may be prepared in several ways, by chemical means. First.—The simplest method is the direct union of the gases. 2H2 + 02 =2H20. Second.—It is always produced by burning hydrogen gas °p any combustible containing it, in the air, and may be con- densed by conducting the products of the combustion through a tube or flue kept cool by immersing it in cold water. CH4 + 20 2 = C02 + H20. Marsh Gas. Oxygen. Carbon dioxide. Water. Third- -Water is produced as one of the products of the action of an acid upon a base, or metallic oxide. Thus :— Potass, hydrate. K—0—H + HNOs = KN03 + H20. Hydric nitrate. Potass. nitrate. Water. Fourth.—The reduction of a metallic oxide by hydrogen or some organic substance containing it. C2H60 +-6CuO at red heat = 3Cu2 + 2C02 + 3H20 2CuO + 2H2 = Cu2 + 2H20. 115. Properties—Physical.—When pure, water is a color- less, transparent, mobile liquid, without taste or odor. When viewed in large quantity, however, it has abluish color. It is a poor conductor of heat and electricity. When water is cooled down below 0°C. (32°F.) it assumes the solid state, called ice. 100 INORGANIC CHEMISTRY. When the temperature is raised to 100°C. (212°F.) in ordinary- conditions, it assumes the gaseous state, called steam. This point is called the boiling point. (See chapter on Heat.) The boiling point is higher than 100°C. under an increased pressure, or when it contains considerable solid matter in solution. Water, at a temperature of 4°C. (39.2°F.), is taken as the unit of specific gravity of liquids and solids. At this temperature it possesses its greatest density. When it is heated above or cooled below this point, it expands and becomes less dense. Water is 773 times heavier than air at 0°C., and 11,147 times heavier than hydrogen. Water expands quite rapidly and with great force, on solidifying, and hence ice is lighter than water. This expan- sion is supposed to be due to the greater space required for the molecules in arranging themselves into crystals. The form of the crystal of water, is hexagonal. It may frequently be seen in small snow flakes received upon a dark surface; the lines of the three equal axes can often be seen with great distinctness. The variations in the boiling point of water are much greater than those of the freezing point, but this last is subject to slight variations of temperature. Water may be cooled in capillary tubes to —15° C. (5°F) before it solidifies, if the tubes remain at rest; but if they are agitated, when at this low temperature, the water will instantly solidify. The agitation favors the movement of the molecules into the position to form crystals, and hence large bodies of water freeze at a higher temperature when agitated by a gentle breeze than when the air is very calm. Although water is converted into vapor most rapidly at 100°C., water (even ice and snow) undergoes evaporation at all temperatures, especially when the air is dry. Owing to its great solvent power for solids, pure water is never met with in nature. There are comparatively few substances which are totally in- soluble in water. When we wish to prepare pure water, we gen- erally resort to the process of distillation, rejecting the first 20 per cent, of that which distills over, and also the last 20 per cent. It is by no means an easy matter to prepare absolutely pure water, even by this process; but, by conducting the process care- fully, with the above precautions, we may obtain a water pure enough for all ordinary chemical purposes. Pure water is gen- erally selected as the solvent of chemical substances which are to be submitted to any chemical change, because the reactions take place more readily in solution than when in the solid state, and because water is a neutral body, which does not complicate the result by taking part in the action, itself. The HYDROGEN AND OXYGEN. 101 Vapor of water is transparent, invisible and colorless. Its den- sity is 9, and its sp. gr., referred to air, is 0.6234. One volume °f water will produce 1696 volumes of steam, or, approximately, one cubic inch of water will produce one cubic foot of steam at 300°C., (212°F.) and absorbs 536.0 units of heat. Chemical Properties.—\Ve have already referred, in speak- lng of the preparation of water, to some of its chemical properties. It unites directly with many metallic oxides to form bases or hydrates, and to some oxides of the metalloids to form acids. CaO 4~ H20 = Ca02H2 S03 -f- H20 = H2S04 co2 + h2o =h2co3 ‘It enters into a feeble union with many metallic salts in solu- tion, and separates with them when they crystallize, as water of crystallization. Certain substances exhibit a marked tendency to comhine with water, or to absorb it from the air, and are used in the laboratory as drying agents. Among these are calcium chloride, sulphuric acid and phosphoric pentoxide. 116. Natural Waters.—As already stated, natural waters are never free from dissolved impurities. They contain gaseous, liquid and solid impurities, varying according to the source from whence derived, the temperature, the nature of the soil or rocks over which it has flowed, or the state of-the air at the time. Natural waters may be divided into potable (or drinkable), mineral and saline. 117. Potable Waters.—To this class belong well and spring Waters, river water, lake water and ice water. The purest natural waters, are rain and snow water from Mountainous and country districts. The purity of rain water paries with the locality where it falls. In the neighborhood of large cities, where the air is charged with the products of large factories, etc., it will contain whatever of these can be washed out of the air. . Sulphuric acid, for example, is comparatively abundant }n the air of large cities. The rain water of London, as given oy Dr. R. Angus Smith, contains 20.5 parts per million, while that of inland places in England contains only 5.5 parts; and tkat from inland places in Scotland, only 2. parts; while from Glasgow it contained 70. parts. The source of the sulphuric acid is mostly from the combustion of coal containing sulphur. The chlorides in rain water, principally sodium chloride, vary with the distance from the sea coast. 102 INORCANIC CHEMISTRY. Ammonium nitrate and nitrite are found in small quan- tities, derived from decomposing organic matter, and from the combustion of coal. Another source of these compounds, is the oxidation of a small quantity of the nitrogen of the air by ozone generated by lightning in its passage through it. Rain water also contains more or less dust and organic matter, which it washes out of the air in falling. The gases found in rain water are carbon dioxide (C02), nitrogen, oxygen, and some- times, in cities, sulphur dioxide (S02) and hydrogen sulphide (IRS). C02 2.4 Peligot’s analyses show Oxygen 6.59 Nitrogen 14. >- c.c. per litre. It will be noticed that the proportion of oxygen in the air' of rain water, is about twice as great as that of the atmosphere. Rain water, as ordinarily collected on roofs of houses, is very much contaminated with both organic and mineral matter washed from the roof on which it falls. It is very liable to become pu- trid from the decomposition of this organic matter, and to breed the larvse of certain insects. Melted snow furnishes a water even purer than rain water, especially if we collect that which falls toward the end of a storm. Ice water varies very much in purity, according to the purity of the water from which the ice is obtained. It is always purer than the water from which it is formed, and when obtained from clear lakes or rivers, it is often the purest of natural waters, owing to the fact that in crystallization of water, or freezing, it leaves the dissolved solids and gases almost entirely in the re- maining water. The absence of the usual gases, however, renders ice-water flat to the taste. Spring and Well waters are simply rain water which has been filtered through a more or less thick layer of soil. The nature and quantity of the dissolved matters will depend upon the nature of the soil and rocks through which it percolates, or over which it flows. In large cities, where the soil is saturated.with filth, the well waters are very impure; while in well drained and mountainous country districts they are much purer. Dangerous organic matter may filter through many feet of soil and poison the water of a well or spring. Shallow wells usually contain much more organic and less mineral matter than deep wells, and are therefore more likely to contain dangerous or unwholesome matters. Wells are essentially a pit for the reception and accu- HYDROGEN AND OXYGEN. 103 mulation of the drainage from the surrounding soil. For con- venience they are usually situated near the dwelling, where the soil receives more or less household waste of various kinds, and are often placed near a cesspool or privy vault. The effect of the geological character of the soil is almost entirely obliter- ated by this local impurity. Such waters, even when dis- gustingly impure, are usually bright, sparkling and palatable. The saline matters held in solution are often much approved by those accustomed to their use. Deep wells may be regarded as those which draw their supply from a depth of 100 feet or more from the surface. In cases where the supply is drawn from below a dense bed of clay or of impervious rock, the well may be considered deep, when such supply is much less than 100 feet below the surface. Deep, wells may be regarded as artificial springs, as both are subjected to the same conditions. Artesian wells are artificial-springs formed by boring into the earth in a low-lying district surrounded by high ground, until a layer of rock or gravel is reached, situated between two im- permeable layers and containing water. The strata must be so curved that their outcrop is on a higher plane than the surface of the well. In such cases the water rises to the surface without pumping, and its character is determined by the nature of the rocks in which the water is found. Surface Waters.—These comprise river water, pond, lake and sea water. The water supply of large cities is usually taken from this class of waters, and consists of spring water, and rain water which has fallen upon a considerable surface of country. Surface waters usually contain a large propor- tion of organic and mineral matters. Surface water, draining from a cultivated district, contains more organic and mineral niatter than that from uncultivated districts, and the character °f it is considerably influenced by the application of fertilizers to the land. River waters are often contaminated by the prac- tice of discharging into them sewage and refuse from various manufactories along their banks. Characters of a Good Drinking Water.—1st. It should be clear and limpid. Cloudy and muddy waters should be avoided. 2d. It should be colorless. A greenish or yellowish color is usually due to vegetable or animal organisms. 3d. It should be odorless ; especially free from sulphuretted hydrogen er putrefactive animal matter. 4th. It should not be too cold, but should have a temperature of from8°C.(46 F.) to 15DC.(60F.). bth. It should have an agreeable taste; neither flat, salty, nor 104 INORGANIC CHEMISTRY. sweetish. A certain amount'of hardness and dissolved gases give a sparkling taste. It should contain from 25 to 50c.c. of gases per litre, of which 8 to 10 per cent, is carbonic acid, and the rest oxygen aiid nitrogen. The air of natural waters is richer in oxygen than the atmosphere above them, viz.: about 33 per cent, of oxygen and 67 per cent, of nitrogen, when the water is fully saturated, which is not always the case. Highly con- taminated waters usually contain less oxygen than the above proportion, because it is used up in oxidizing the organic matter. 6th. It should be as free as possible from dissolved organic matter, especially of animal origin. 7th. It should not contain too great an amount of hardness. A certain quantity of saline matter is necessary, however, to give it a good taste. It should not contain over 3 or 4 parts of chlorine in 100,000 parts of water. 118. Water Analysis.—We have seen that natural waters are never pure, but contaminated by various kinds of foreign matter to which they have been exposed. These impurities may be harmless to the human economy, or they may be very harm- ful. It is the object of the analyst to determine, as nearly as possible, the nature and amount of the impurities found in a water, so as to form an opinion as to its healthfulness. It has been proven, beyond doubt, that water is a fruitful dis- seminator of disease. It is believed that the disease produced in such cases is due to microscopic organisms, and that the organic matter of the water simply furnishes a suitable solution in which they may live and grow. It is also known that these organisms grow best in solutions of animal organic matter; hence, waters contaminated with animal matters are looked upon as much more dangerous than those containing vegetable matter. If the above idea be correct, it is evident that chemical an- alysis cannot detect the disease-producing element, although it can tell pure from impure water. Several methods are in use among chemists for the purpose of forming an opinion as to the character of drinking waters. The elements usually relied upon in a sanitary examination, are total residue left on evaporation, the loss in weight of this residue on ignition at a dull red heat, the chlorides, the nitrates and nitrites, ammonia, organic carbon and nitrogen, and the quantity of oxygen the water will absorb from an acid solution of potassic permanganate. Poisonous metals should, of course, be looked for where there can be any suspicions of their presence. HYDROGEN AND OXYGEN. 105 119. Total Residue.—The amount of residue left on evapo- ration serves, in a crude way, to indicate the amount of solids, but is only approximate and of no significance unless it reaches more than 30 or 40 grains per gallon. This residue will, of course, vary with the hardness, or the amount of soluble constituents in the soil. By igniting the solids (heating them over a lamp) We may expel all volatile and organic matter, including the Water held by the calcium sulphate, at the temperature of 100°C., (the temperature generally used in drying the residue), some carbon dioxide from carbonates, and oxides of nitrogen from nitrates and nitrites. The residue left after ignition gives a rough ffiea of the mineral matters present, and the loss should never reach 50 per cent, of the total residue. 120. Chlorine in potable waters is very largely derived from the sodium and potassium chlorides of urine and sewage. -The average amount of chlorine in urine is not far from 5 parts per 1000 , or 500 parts in 100,000 parts of water. The average found in sewage is about 11.5 parts per 100,000. Over 5 parts of chlorine Per 100,000 may be considered, in most cases, to be due to pollu- tion of the water by sewage or animal excretions. Proximity to the sea does not materially affect the amount of chlorine, in Well waters. Too much dependence cannot be put upon the amount of chlorine in a water, as a means of judging of its purity, for vegetable matter may exist in dangerous quantity without its presence being indicated by the chlorine present. Chlorine is estimated by a standard solution of argentic nitrate. 121. Hardness.—The hardness of water is produced princi- pally by the acid carbonates, and the sulphates of calcium and magnesium. The acid carbonates are decomposed by boiling, aQd the neutral salts precipitated :— Hardness due to these salts is called “ temporary,” while that due to the sulphates of these metals is called “ permanent.” The hardness of a water seems to have little or no influence upon the health of those who use it. Hardness is estimated by uieans of a standard solution of soap. Temporarily hard waters may be softened by adding lime in sufficient quantity to neu- tralize the excess of carbonic acid in the water, when the car- bonate (CaCo3) or (MgCo3) is formed, which settles to the bottom. The alkaline carbonates (Na2Co3 and K2C03) may be used to Precipitate permanent hardness and soften the water. Wood CaH2(C03)2 = CaC03 + H20 + C02. 106 ashes, which contain the latter of these salts, is frequently used by washerwomen to soften water for washing. 122. Nitrates and Nitrites.—These salts are usually looked upon as evidences of former contamination of a water by nitro- genous organic matter. The decomposition of organic matter of animal origin, in waters containing dissolved oxygen, yields nitrous and nitric acid, which combine with bases present to form salts of these acids. Rain water contains a small quantity of these acids, but a larger quantity indicates that the water is un- dergoing, or has undergone, a natural process of purification from animal matters. The quantity found usually indicates the amount of matter thus decomposed. This purifying process goes on more slowly in river and lake waters than in well wTaters, because the exposure to oxygen in the latter is more complete while filtering through the soil, than in a body of water. Deep wells may be allowed to contain more nitrates than shallow ones, for the organic matter may all be destroyed by the filtering pro- cess through the soil into a deep well, while in the shallow one some organic matter, germs, and spores capable of causing dis- ease, may pass undecomposed through the shorter distance. A careful estimation of nitrates gives, therefore, considerable knowledge of the past history of a water, and is regarded by chemists as of great importance. A very easy and delicate test for nitrates and nitrites in water, is the following: Make a solution of diphenylamine in pure, strong sulphuric acid, adding a little pure water to make a clear solution. To the’suspected water add some of the sulphuric acid, then a few drops of the above solution. If nitrates or nitrites are present, a deep blue solution will be formed at once. This test may be used by any one, and will give some idea of the safety of a drinking water. 123. Moist Combustion.—By this is meant the oxidation of the organic matter found in a water by adding to it a mea- sured quantity of potassium permanganate, with some sulphuric acid, and determining the oxygen absorbed from this salt by the organic matter present. This method cannot distinguish between vegetable and animal matters, neither will it measure the oxygen consumed in oxidizing nitrites to nitrates, or ferrous to ferric salts. In the presence of these salts it may give erroneous re- sults. Most chemists regard the process as of some value in giving an idea of probable pollution by organic matter, as it has been shown that dangerous organic matter is more easily oxidized than that which is harmless. INORGANIC CHEMISTRY. HYDROGEN AND OXYGEN. 107 124: Argentic Nitrate Test.—It has been proposed to estimate the amount of organic matter in water by the addition of argentic nitrate, and, after filtering out the precipitated chlo- ride and sulphide of silver, to set the filtered water in a strong light for twenty-four hours. The organic matter present in the water, reduces a portion of the silver to the metallic state, and forms a black deposit. This may be filtered out and weighed, and from the quantity, we may judge of the probable organic purity of the water. As a qualitative test, this may easily be performed and give proximate results. 125. Ammonia.—The spontaneous decomposition of organic matter in water first affords ammonia, then nitrites, and finally nitrates. This fact is so generally conceded as to make an esti- mation of the ammonia found in a water, a very important part of the sanitary examination. By distilling a measured portion of the water under exami- nation, all the ammonia is found to pass off and condense with the first portions distilled. To determine the amount of ammonia present in the distillate, it is only necessary to compare the color produced in it by a small quantity of Nessler’s reagent,* with the color produced by a known quantity of ammonia added to some pure Water in another tube.f After having freed the water from ammonia, as above, if we add to it a strongly alkaline .solution of potassium permanganate and continue the distillation, the nitrogenous organic matter present gJves up its nitrogen in the form of ammonia, which is denomi- nated “ albumenoid ammonia.” This may be determined in the same manner as the “ free ” ammonia above. This method of examining a water for nitrogenous matters, is generally looked upon as one of the best methods in use for the purpose. 126. Organic Carbon and Nitrogen.—Drs. FranklandJ and Armstrong, in 1868, proposed to burn the organic matter in the residue left on evaporating the water to dryness, and by col- lecting and weighing the nitrogen and C02 produced, to estimate the amount of nitrogenous matter present. This process is diffi- cult to conduct, and is open to serious errors; it is, therefore, little employed. 127. Living Organisms.—It has lately been proposed to * eSS^er'-S reagent is a strong solution of potass, iodide, saturated with mercuric iodide, and rendered alkaline with sodic hydrate, t See Water Analysis by Wanklyn. London, 1876, p. 32. + Water Analysis by Frankland. Philadelphia, 1880. 108 INORGANIC CHEMISTRY. test “ organic vitality ” of waters designed for drinking purposes, by adding enough gelatin solution to make the water slightly viscid, place it in a tall cylinder and allow it to stand in a light place from twelve to twenty-four hours. The gelatin prevents the free movement of the organisms in the water, and allows us to see their growth, by the opalescent spheres caused by great numbers of them congregated in a small spot, and springing from a single parent. By the number and rapidity of the growth of these spheres, we may form some idea of the organic vitality or the power of the water to grow organisms. This method may be modified by floating upon the water, contained in a tall narrow cylinder or test tube, a thick solution of gelatin, and then cov- ering the sides of the tube with paper, admitting light by a small hole in the paper opposite the layer of gelatin. On standing from 12 to 24 hours in a light place, the organisms existing in the water will be found entangled in the gelatin film, and may be removed with a pipette and placed under the microscope. This process aims to judge of the character of the water by the character of the organisms found growing in it. If large numbers of putrefactive bacteria be found, it would be evidence of putrefying organic matter. We have thus briefly outlined the methods in use for testing drinking waters, for the purpose of giving the student some knowledge of the subject, without going into tedious details, which are intended only for the chemist, and which do not come within the scope of this work. 128. Purification of Water.—Water may be separated from suspended impurities by filtration, i. e.,by passing it through any porous substance not soluble in the water, as clay, sand, charcoal, brick, unglazed earthenware, unsized paper, etc. For filtering large quantities of water for cities or manufactories, sand or brick is to be preferred. For filtering water for family use, a brick partition two or four inches thick, built in a cistern, works well. The water is delivered in one apartment and pumped from the other for use. Or, a barrel in the bottom of which several holes are bored, may be filled with alternate layers of gravel, sand and charcoal, and placed over the mouth of the cistern or reservoir, through which the water may be filtered. Such a filter, when freshly made, will remove a part of the dis- solved organic matters as well as suspended matters. The sili- cated carbon filters found in the market, made of pulverized carbon and cement, are much neater, and will also oxidize a por- tion of the dissolved organic matter in passing the water through 109 them, especially when new. Porous stone filters, made from a silicious stone, are to be found in the market, which filter rapidly and very perfectly. Spongy iron filters, made by roasting hematite with coal, are still more active in destroying organic matter and putrefactive germs. We have already referred to methods of precipitating the hardness from water. Dis- tillation, as a means of purifying water, has also been referred to. Freezing purifies water, and removes, to a considerable degree, the mineral as well as organic matters; but freezing cannot make a dangerous water perfectly safe. Numerous in- stances show that disease may be communicated as surely by ice, as by unfrozen water. 129. Mineral Waters.—Under this name are included such waters as, from some dissolved substances, have a greater or less therapeutical value. These vary so much in the character of the dissolved substances, that no exact classification of them can be made ; but they may be roughly classified as follows .— 1st. Carbonated waters, those which are charged with car- bonic dioxide or carbonic acid. 2d. Sulphuretted Waters, those which contain sulphides of hydrogen or one of the alkaline metals, in notable quanti- ties. They are used for baths as well as for drinking. 3d. Alkaline Waters, those containing considerable quantities of carbonates or bicarbonates of the alkaline metals—sodium, potassium, or lithium. 4th. Saline Waters, those containing the neutral salts, such as the chlorides, bromides, or iodides of the alkalies or alka- line earths. Chalybeate Waters, those containing some one of the compounds of iron. Closely allied with these in properties, are those containing manganese. Gth. Thermal Waters, or such as come to the surface at a temperature above that of 20°C. (68° F.). Some of these springs contain so little mineral matter as to be of no im- port ; the only value, if any, being in the temperature. They are used principally for baths. 130. Officinal Forms.—Aqua. Natural water in the purest attainable state. Aqua distillata. Take of water 80 pints. Distill two pints, reject, then distill 64 pints. (U. S. P.) The transparency or color of distilled water should not be affected by lime water, H&BaCl„ AgNOs, or (NH4)2Ca04. ihe term aqua, in the U. S. P., is used to designate a solution °f a gaseous or volatile body in water, as aqua ammoniae, HYDROGEN AND OXYGEN. 110 INORGANIC CHEMISTRY. aqua chlorinii. Liquor, a solution of a fixed or solid body, as Liquor Ferri Nitratis, Liquor Plumbi Subacetatis. A Decoction is a solution made with boiling water, usually of a vegetable product. An Infusion is a solution formed by subjecting a body for a short time to either cold or warm water. Maceration is the long continued action of water at the ordi- nary temperature. Digestion, the same with hot but not boil- ing water. Lixiviation or leaching is the process of pouring water upon a porous mass of any .body, for the purpose of dissolving out any soluble matters. 131. Physiological Use.—Water exists in all the tissues of the body, and in all foods and drink. A healthy adult takes'on an average, about 2.5 litres of water in 24 hours ; and loses by the skin, lungs, kidneys and faeces a little more than this; the excess coming from the oxidation of the hydrogen of the food and tissues. Water constitutes about from 65 to 70 per cent, of the whole body, being in slightly larger proportion in the young than in the adult body. The water in the tissues serves as a sol- vent for the various proximate principles intended for nourish- ment of the tissues, or coming from their waste, and intended for excretion. The evaporation from the skin serves to carry off the superfluous heat of the body. 132. Hydrogen Peroxide (H202).—The simplest way of preparing a diluted solution of this body is to pass a stream of C02 through water containing in suspension barium-peroxide. Ba02 + C02 + H2 O = BaC03 + H202. The insoluble barium carbonate may be separated by filtration, best through asbestos filters. This solution may then be evapo- rated in a partial vacuum. In its purest form, it is a syrupy, colorless liquid, having an odor resembling that of chlorine or ozone, and a tingling metallic taste. It is still liquid at—30° C. (—22°F.), but at temperatures above 22° C. (71.6aF.) it changes, rapidly into water and oxygen. This change takes place gradu- ally at ordinary temperatures.*. In diluted solution it is much more stable, and may be boiled without suffering decomposition. The solutions of this substance are decomposed by many fine metallic powders. In most of its reactions it acts as an oxidizing agent. Argentic oxide, however, is reduced to the metallic state by it. Tests.—To the suspected solution, add a little starch solution, then some potassium iodide, and finally a few drops of a solution of ferrous sulphate. If any hydric peroxide be present a blue color will appear. Very delicate. Uses.—Oxygenated water, or hydric peroxide, is used as a bleaching agent for the hair and skin, converting brunettes into blondes. It is often used to renovate old pictures, the whites of which have become dingy. It has been used as a disinfecting solution, to ulcers, in ozaena, diphtheritic and scarlatinal sore throats, or where the membrane has invaded the nose. Also used as a test for pus in urine, with which it causes an effer- vescence. FLUORINE. THE CHLORINE GROUP. Symbol. Atomic Weight. State. Fluorine, F. 19 ? Chlorine, Cl. 35.5 gas. Bromine, Br. 80 liquid. Iodine, I. 127 solid. 133. The elements of this group are electro-negative, fluorine being most negative, and the iodine least so. They have a characteristic, pungent odor, and act as disinfectants and bleach- ing agents. They enter into direct union with many of the metals to form binary compounds. They form compounds with hydrogen, with well marked acid properties. They have little affinity for oxygen, but form several oxacids and salts, all of which are rather unstable. They form the following com- pounds :— HC1. CloO C1203 C1204 HC10 hcio2 hcio3 hcio4. HBr. — — — HBrO — HBr03 HBr04. HI. _ — I204 HIO hio2 hio3 hio4. FLUORINE. F. = 19. 134. Little if anything is known of this element. It cannot well be prepared. The sources of fluorine compounds are the native floor spar, calcium fluoride, and cryolite—a sodium and alumi- num fluoride. 135. Hydrogen Fluoride—Hydrofluoric Acid.—This acid is obtained by the action of sulphuric acid upon powdered fluor spar, with the aid of a gentle heat. The operation is usually conducted in a lead or platinum vessel, as the acid attacks glass and most metals. The acid is a colorless, transparent gas, with a pungent odor, very irritating to the skin and mucous membranes. It is readily soluble in water, CaF2 + H2S04 = CaS04 + 2HF. 112 INORGANIC CHEMISTRY. forming a colorless, highly acid and corrosive liquid, with a pungent odor. Care must be taken, in using it, not to allow it to come in contact with the skin, as it produces a painful ulcer, which heals with difficulty, and also constitutional symptoms of considerable severity. The boiling point of the liquid is between 15° and 20°C. (59 and 68°F.), and it has a specific gravity of 1.060. The most charac- teristic property of hydrofluoric acid, is its power of dissolving glass by removing its silicon. This property is utilized for etch- ing glass. The article to be etched is first coated with a thin layer of melted wax or paraffin, and the characters are then scratched through the wax with a steel point, so as to expose the glass where the etching is to take place. If the liquid is to be used, a wall of wax is built up around the characters and the liquid is poured into the inclosure. The characters thus etched are transparent. It is more common to invert the glass, wax downward, upon a leaden dish containing the fluor spar and sul- phuric acid, and expose it to the fumes until the etching is as deep as desired. The etchings in this case are opaque, presenting the appearance of ground glass, and more easily seen. Fluorine forms no oxides. CHLORINE. Cl. = 35.5. D. = 35.5. Sp. Gr. = 2.47. Equivalence I, III, V or VII. 136. Occurrence.—Chlorine always occurs in combination, in nature. The chlorides of sodium, potassium, magnesium and ealcium occur in springs. Usual source, sodium chloride or common salt. 137. Preparation.—By the action of sulphuric acid upon sodium chloride in the presence of manganic oxide. 2H2S04 + Mn02 + 2NaCl = Na2S04 + MnS04 + 2H20 + Cla 4HC1 + Mn02 = MnCl2 4 2H20 + Cl2. Or, by acting upon manganic oxide with hydrochloric acid. For a slow continual evolution of chlorine, as for disinfecting purposes, moistened chloride of lime is exposed to the air. The calcium hypochlorite is decomposed by the carbonic dioxide of the air, and chlorine is set free. For a more rapid evolution, we may use the same salt with a dilute acid. 138. Properties—Physical.—At ordinary temperatures chlorine is a greenish-yellow, pungent, suffocating gas. It is CHLORINE. 113 causing inflammation of the air passages. It is nearly two and a half times heavier than air ; it is soluble in Water, one volume of water dissolving nearly three volumes of the gas at 10° C. (50°F.) The solution, aqua chlorinii U. S. P., is a greenish-yellow liquid, possessing the properties of the gas, but slowly changing, in the light, into hydrochloric acid. It should bleach but not redden litmus paper. Under a pressure of four atmospheres, at ordinary temperatures, or at a temperature of 40° C. (—40° F.), it is condensed to a dark yellow liquid. Chemical Properties.—The affinities of chlorine are very strong and extensive. It is characterized by its strong tendency to combine with hydrogen and the metals, to form chlorides. It combines directly with many elements (finely divided copper, antimony or arsenic), with the evolution of light and heat. Its attraction for hydrogen is so strong that a mixture of these gases combine with an explosion, when exposed to direct sunlight, the lJght of burning magnesium, or the electric light. It burns feadily in an atmosphere of hydrogen. It is capable of existing jo two allotropic states; the one active, and the other passive. I he passive or inactive form is the one obtained when the gas is prepared in the dark ; and when prepared in daylight it is very &ctive in its properties. When the same element is capable of existing in two or more forms, having different properties, these forms are called allotropic conditions; the property is called allotropism. One of the most marked chemical properties of chlorine, is its affinity for hydrogen. So great is this affinity that many organic compounds are spontaneously decomposed by it; the chlorine com- bining with the hydrogen of the compound and setting the carbon free. A paper wet with turpentine and plunged into a jar of chlorine, takes fire and deposits the carbon as a dense smoke, while fumes of HC1 fill the jar. The well known bleaching and disinfecting powers of chlorine are due to its affinity for hydrogen. Most vegetable colors, when moist, are readily discharged by chlorine. The chlorine combines with the hydrogen of the water and sets free the oxygen, which, in the nascent condition, is ? Powerful oxidizer, and decomposes the coloring agent or organ- ized germ, as the case may be. In some cases the chlorine acts directly upon the organic matters, uniting with a portion of their hydrogen to form HC1, and a portion of it entering the molecule to take the place of the hydrogen removed. Thus, with marsh gas, hydrochloric acid and methyl chloride are pro- duced. CH4 -f Cl, = CH3C1 + HC1. 114 INORGANIC CHEMISTRY. 139. Hydric Chloride.—Hydrochloric Acid.—Acidum Muriaticum—Acidum Hydrochloricum (U. S. P.).—HC1 = 1 -)- 35.5 = 36.5. Hydrochloric acid occurs very sparingly in nature. It is found in volcanic gases, and in the gastric juice of mammals. 140. Preparation.—The acid is usually prepared from sodium chloride or common salt, by treatment with commercial sulphuric acid, with the aid of a gentle heat. The process is sometimes conducted as a special process, but a large quantity of the acid is prepared, as a side product, in the Fig. 32. Preparation of HC1. preparation of sodium carbonate by Leblanc’s process. The first step in this process is to. treat the salt with sulphuric acid, and thus convert it into a sulphate. The hydrochloric acid set free by this process, is collected and sold as impure hydrochloric acid. H2S04 + 2NaCl = 2HC1 + Na2S04. The acid may be prepared in small quantity by the direct union of equal volumes of chlorine and hydrogen, under the influence of sunlight or the electric spark. (See Art. 85.) 141. Properties.—Hydrochloric acid is a colorless, trans- parent gas, having a pungent, penetrating odor, a sharp, sour CHLORINE. 115 taste, an acid reaction, and produces great irritation of any tissue with which it comes in contact. It is irrespirable and extin- guishes a flame. It is very soluble in water. One volume of this liquid dissolves 450 volumes of the gas at 15° C. (59° F.) This solution forms the ordinary muriatic acid. The specific gravity of the solution is 1.21, and contains about 40 per cent. °f HC1. The sp. gr. of the gas (air = 1) is 1.264 ; the density (hydrogen = 1) is 18.25. Under a pressure of 40 atmospheres, at 10° C. (50° F.), it condenses into a colorless, limpid liquid, having a sp. gr. of 1.27. A strong solution in water fumes strongly in the air, giving off a part of the gas. On being heated, it gives off its acid rapidly. The strongest commercial acid contains from 25 to 80 per cent, of HC1. The commercial muriatic acid is yellow in color, due to the presence of ferric chloride. It also contains other impurities, and is used only for manufacturing purposes. Acidum Muriaticum or Acidum Hydrochloricum, U. 8- P., is a colorless liquid of sp. gr. 1.16. It contains 31.9 per cent, of HCL, with traces of impurities. Acidum Muriaticum Dilutum, Acidum Hydrochlo- ricum Dilutum, U. S. P., is made by diluting the stronger acid with water. (Strong acid 3 parts, distilled water 13 parts). The sp. gr. = 1.049, and contains 10 per cent, of HC1. Pure hydro- chloric acid should be colorless, and when diluted with distilled water, should give no precipitate with H2S, NH4OH in excess, °r BaCl2, and should not dissolve gold leaf (absence of HN03). 142. Chlorine and Oxygen.—There are three oxides of chlorine known. C120, Hypochlorous Oxide or Anhydride. C1203, Chlorous Oxide or Anhydride. C1204, Chloric Tetroxide. The oxides of chlorine are all unstable compounds, very prone to decomposition, and of little importance. 143. Hypochlorous Anhydride is obtained by acting upon mercuric oxide with dry chlorine, as a blood-red mobile liquid below 20° C. (68° F.), HgO + 2C12 = HgCl2 + ClaO. Above this temperature it is a yellowish, pungent gas, resembling chlorine in many of its properties. It is a more powerful bleaching and disinfecting agent than chlorine, owing to the ease with which it decomposes. Water dissolves 200 times its volume of it, forming a colorless solution of hypochlorous acid. It sometimes decomposes with a slight jar, or even spontaneously, with the separation of chlorine and oxygen. Hypochlorous acid is un- 116 INORGANIC CHEMISTRY. important, but it forms a series of salts called hypochlorites. A solution of the sodium salt, liquor sodae chlorinatae (U. S. P.), (Labarraque’s solution), potassium hypochlorite, liquor potassii chlorinatae, and calcium hypochlorite, or chloride of lime, are the most important compounds. * 144. Chlorous Anhydride may be formed by treating po- tassium chlorate, KC10;i, with dilute nitric acid in the presence of arsenious oxide. It is a greenish-yellow explosive gas, soluble in water, with which it unites to form chlorous acid, HC102, a very unstable body which has not been isolated, but which forms chlorites. None of these salts are of importance. 145. Chloric Tetroxide may be obtained by treating potas- sium chlorate with strong sulphuric acid, as a yellow explosive gas. It is a powerful oxidizing agent. Below—20° C. (—4° F.) it is an orange-red liquid. It forms no corresponding acid. 146. Chloric Acid (HC10;!) and perchloric acid (HC104) are also known, but are very unstable, and like those before mentioned are powerful oxidizing agents. Potassium chlorate is the only salt of note, which will be described under potassiuu. BROMINE Br = 80. Specific gravity 3.187 at 0° C. (32° F.). Density of vapor 80. . 147. History and Occurrence.—Discovered by Balard, in sea salt, in 1826. It never occurs native, but is found combined with the alkaline metals and magnesium, in sea water, certain salt springs and the ashes of seaweeds. It is obtained from any of the above compounds by distilling them with manganic dioxide and sulphuric acid. MgBr2 + Mn02 + 2H2S04 = Br2 -f MgS04 + MnS04 + 2H20. 148. Properties—Physical.—Bromine is a blood-red fum- ing liquid, possessing a strong, disagreeable, pungent and irritat- ing odor somewhat like that of chlorine. It corrodes animal tissues. It boils at 63° C. (145.4° F.), but gives off fumes at all temperatures above, its freezing point, —24.5° C. (—12° F.). Water dissolves 3.2 per cent, of its volume at ordinary temper- atures. It is soluble in alcohol, ether, chloroform and carbon disulphide, imparting its color to the solutions. Chemical.—The chemical properties of bromine are similar to those of chlorine, but somewhat feebler. Bromine is poison- ous. It may be recognized by its color, odor, or by the yellow IODINE. 117 or browui color of its solution in chloroform. It forms a yellow or orange color with starch paste. A solution of argentic nitrate precipitates it from its solutions, as a yellowish-white powder, which is soluble with difficulty in ammonium hydrate. 149. Hydrogen Bromide (HBr).—This acid may be pre- pared by treating phosphorus, immersed in cold water, with bro- mine, and distilling the resulting liquid. The bromine combines with the phosphorus, forming PBr5, which is decomposed by the water into phosphoric and hydrobromic acids. It may also be prepared by the action of sulphuric acid (7 parts acid to 1 of water), upon a hot solution of potassium bromide. (Squibb.) It is a colorless gas, producing white clouds in the air, is readily soluble in water, forming a strongly acid solution, the properties of which closely resemble those of hydrochloric acid. The acid is used in medicine, and has about the same action as the other bromides, but is more active and rapid in its action. 15D. Bromine and Oxygen.—No oxides of bromine are known. There are, however, three acids known, corresponding to those of chlorine. They are hypobromous acid, HBrO, bromic acid, HBr03, and perbromic acid, HBr04. They are of little importance, and but one salt of the three acids is of interest to the physician, and that is sodic hypobromite, NaBrO, used as a reagent for the estimation of urea. It is pre- pared in solution by adding bromine to a solution of sodium hydrate, having care to keep the mixture cool by immersion in cold water. 2NaOH + Br2 = NaOBr -f- NaBr H20 IODINE. I = 127. 151. Occurrence.—Iodine occurs in the same localities with chlorine and bromine, but in more sparing quantities than the latter. It is obtained mostly from the ashes of certain seaweeds collected in Scotland and France. The ash is leached with water, the solution evaporated down until the other salts crystallize out, leaving the more soluble iodides in solution. The solution is now treated with chlorine, to set the iodine free, aided by a sufficient heat to volatilize the iodine, w'hich is condensed in suitable con- densers and purified by sublimation. 152. Properties.—Iodine is a bluish-black crystalline solid, occurring in bright scales or tablets, which emit, even at ordinary Specific gravity, 4.95. 118 INORGANIC CHEMISTRY. temperatures, a very irritating pungent vapor. When heated, they melt at 107° C. (225° F.), and boil at 175° C. (347° F.), giving a beautiful violet colored vapor, of the density of 127. This vapor condenses directly to the crystalline scales. When applied to the skin, it produces a yellowish-brown stain, which disappears after a time ; but, after repeated applications, it causes irritation, thickening and desquamation of the cuticle. It is very slightly soluble in water (1 part to 7000), but the addition of potassium iodide renders it freely soluble. It is freely soluble in alcohol, ether, chloroform, glycerine, carbon disulphide and ben- zole. When pure it should leave no fixed residue when volatilized. Cyanogen is sometimes found as an impurity. This may be de- tected by heating the iodine on a water bath, covered with a cold watch glass, upon which the white crystals will condense. Its solutions, when cold, yield a deep blue color with boiled starch, which precipitates on standing. Boiled starch is used as an an- tidote in cases of poisoning. 153. Medical Uses.—It is used externally as a counter irritant and discutient; internally, as an antizymotic and altera- tive. In large doses, it acts as an irritant poison. It is elimi- nated by the kidneys, saliva and faucial mucous membrane, but not by the skin. In administering it, silver spoons should be avoided, as it attacks them. The following preparations of free iodine are officinal: Iodum, Tinctura Iodinii, a solution in alcohol (3j to Oj). When freshly made, it is precipitated from this solution with water, but after some time it undergoes changes which prevent this. The so-called colorless tincture is made by adding ammonium hydrate to the above tincture, in sufficient quantity to decolorize it by converting the iodine into ammonium iodide. Tinctura Iodinii Composita is a solution of iodine and potassium iodide in alcohol. Liquor Iodinii Composita (Lu- gol’s solution), is a solution of iodine and potassium iodide in water. Unguentum Iodinii and Unguent. Iodinii comp., the former containing iodine and the latter iodine and potassium iodide rubbed up with lard, are also officinal. 154. Hydric Iodide, or Hydriodic Acid (HI).—A solu- tion of this acid is prepared by passing hydric sulphide through water.containing iodine in suspension, until the iodine disappears, and then filtering from the precipitated sulphur. The acid, when pure, is a colorless gas, fuming in.the air, having a penetrating odor resembling in most of its properties those of hydrochloric acid, although less stable and less active. Acidum Hydrio- SULPHUR. 119 dicum Dilutum is officinal, but is prone to decomposition, with the liberation of iodine. Iodides of sulphur, ammonium, arsenic, mercury, lead, iron, potassium and sodium are also used in medicine. 155. Iodine and Oxygen.—There are three or four unim- portant and unstable oxides of iodine known. I203,1205, and possibly I207. Two oxygen acids are known, iodic, HI03 and periodic, HI04 or H2I06H3 (Thomsen & Basarow). The first is obtained by treating iodine with nitric acid, and the second by passing chlorine through an alkaline solution of sodium iodate. The first, when pure, appears as a white crystalline solid, and the second as colorless crystals. Both are very soluble in water, are easily decomposed, and form salts. The following compounds are also known : IC1, IC13, IC13, IBr, IF15 and NI3. The last is a very explosive compound. SULPHUR GROUP. Sulphur, S = 32. Selenium, Se = 79.5. Tellurium, Te = 128. 156. Group Properties.—The elements of this group are all solid at ordinary temperatures. Their quantivalence. is usually dyad, tetrad, or hexad. They combine with hydrogen to form hydracids, containing two atoms of hydrogen. In binary com- pounds they are usually dyad. They form two series of oxides and corresponding acids, R02 and R03, H2R03 and H2R04. In the first series their quantivalence is tetrad, and in the second hexad. Sulphur is the most electro-negative, and tellurium the least so, but all are decidedly negative. SULPHUR. S = 32. Sp. gr., 2.04. Density of vapor, 32. Melts at 114° C. (237° F.) 157. Occurrence.—Sulphur was known to the ancients. It occurs in volcanic regions, and is brought mostly from Sicily and Iceland. The sulphur occurs native, mixed with clay, from which it is separated by distillation. This element also occurs as sul- phates in the minerals, gypsum, CaS04. 2Aq, Barite, BaS04, etc ; and as sulphides of iron, .copper, nickel, and, in fact, with many of the metals. 120 INORGANIC CHEMISTRY. 158. Preparation.—It is prepared from the native sulphur mixed with more or less earth, found in volcanic regions of Sicily, by distilling it from the non-volatile impurities. A second distillation is necessary to prepare the refined sulphur of the market. The second distillation is conducted in a retort, the vapor being conducted into a large chamber (Fig. 33), where, if the process is conducted slowly, it collects in the form of a crystalline powder called flowers of sulphur. If the process is conducted more rapidly, the chamber becomes hot, and the sul- Fig. 33. REFINING OF SULPHUR. phur then condenses to a liquid at the bottom, whence it is drawn off into moulds forming ordinary roll sulphur or brimstone. Sulphur is also obtained in some localities from iron pyrites, by piling it in heaps mixed with wood, to which fire is applied. The ore gives up a part of its sulphur, which melts and runs into cavities made under different parts of the heap. 159. Properties-—Physical.—Sulphur, in its ordinary form, is a lemon-yellow solid, melting at 114° C. (234° F.), and boiling at about 440° C. (824° F.), giving off* a brownish-yellow vapor, which in condensing returns directly to the solid state. Sulphur SULPHUR. 121 is brittle, tasteless, odorless, a non-conductor of heat and electri- city, and generates negative electricity when rubbed. It is in- soluble in water, and almost so in alcohol. It is slightly soluble Hi aniline, phenol, benzol, benzine and chloroform. The best solvent is carbon disulphide, 100 parts of which dissolves 37 parts ,at ordinary temperatures. Allotropic Forms.—Sulphur is capable of existing in three allotropic modifications ; two crystalline, and one amorphous and plastic. The first variety is that found native, and occurs as octahedra of the second system. (See Art. 76.) It is freely soluble in carbon disulphide, from which the crystals separate on evaporation. The second variety is produced by crystallization from sulphur melted at high temperatures. This variety occurs as yellowish-brown, transparent prisms of the monoclinic system, °f sp. gr. 1.98, insoluble in carbon disulphide, and gradu- ally changes into the first variety. Since- it crystallizes in two distinct systems, sulphur is said to be dimorphous. By heating sulphur, it melts at about 114°C. (234°F.) to a yellowish liquid; °n raising the temperature to about 150° C. (302° F.), it becomes viscid and dark colored, and cannot be poured from the vessel; at a higher temperature, approaching its boiling point, it again becomes liquid. If sulphur, in this second liquid stage, be sud- denly cooled by pouring into water, it assumes a soft, plastic, transparent mass, capable of being moulded like wax. This variety, like the preceding, gradually changes into the first va- nety, becoming opaque, yellow and crystalline. Density of vapor at 500° C. (932° F.) = 90 = S6. At 1000° O. (1832° F.) = 32 = S2. Chemical.—When heated in the air, sulphur takes fire and burns with a pale blue flame, and evolves abundant fumes of sulphurous anhydride, S02. It is generally strongly electro-nega- tive and resembles oxygen in many of its compounds. In a few compounds it is electro-positive. It unites directly with many °f the metals, especially when in the melted state, some metals taking fire and burning readily in its vapor. It forms the basis uf a large and useful class of compounds, many of which resem- ble in composition the corresponding compounds of oxygen. Thus, carbon disulphide, CS2, corresponds to carbon dioxide, C02. Corresponding to hydric oxide, H20, we have hydric sul- H2S, and to cyanic, CNOH, we have sulpho-cyanic acid, CNSH. Corresponding to carbonic acid, H2C03, we have sulplio- carbonic acid, H2CS3. 122 INORGANIC CHEMISTRY. 160. Uses.—Sulphur is used in the arts, in the manufacture of sulphuric acid, H2S04, as a bleaching agent for straw and woolen goods, and in the manufacture of matches and gun- powder. In medicine it is used as a parasiticide, and as a gentle laxative, although not as frequently as formerly. It is innocuous. 161. Officinal Forms.—1. Sulphur sublimatum, com- mercial flowers of sulphur. 2. Sulphur lotum, washed sulphur. Flowers of sulphur usually contain small quantities of sulphurous oxide, which is removed by washing with hot water. 3. Sulphur praecipitatum, lac sulphuris, milk of sulphur, is made by boiling for two hours sulphur and fresh slaked lime suspended in water. 3Ca02H2 ~1~ 2S2 — 2CaS -f- CaS203 -f- 3H20. The filtered solution of CaS and CaS203 is then diluted and treated with dilute hydrochloric acid as long as a precipitate forms. The calcium chloride, being very soluble, remains in solution. The sulphur is to be thoroughly washed with water, until free from acid. It is a fine white powder, easily suspended in water and viscid liquids. 4. Unguentum sulphuris, U. S. P., con- tains one part of sulphur to two of lard. 162. Sulphur and Hydrogen.—Two compounds of sulphur and hydrogen are well known—hydric sulphide, H2S, and hydric persulphide, H2S2. The first only is of sufficient interest to merit description here. Hydric sulphide, hydro-sulphuric acid and sulphuretted hydrogen are synonymous terms. It is found in volcanic gases, in some mineral springs, and as a re- sult of the decomposition of organic matter containing sulphur. At an elevated temperature, the two elements may be made to unite directly. 163. Preparation.—The usual method of preparing it is to act upon a sulphide, usually ferrous sulphide (FeS), with dilute sulphuric acid. 164. Properties.—H2S is a colorless, transparent gas, of an unpleasant odor resembling that of rotten eggs, soluble in water, to which it imparts acid properties. It is somewhat heavier than air, its density being 17 and its sp. gr. 1.177. At a tem- perature of —74° C. (—101.2° F.), or under a pressure of 17 atmospheres at 10° C. (50° F.), it condenses to a colorless, mobile liquid, which at —85° C. (—121° F.) becomes an ice-like solid. 2CaS + CaS203 + 6HC1 = 3CaCl2 + 3H20 +. 2S2. SULPHUR. 123 It burns with a blue flame, producing water and sulphurous oxide or anhydride, S02. If the supply of oxygen is* deficient, H20 is produced, while the sulphur is deposited free. It is decomposed by chlorine, bromine, iodine, and oxidizing agents in general. It is also de- composed by sulphurous oxide. When the gas is allowed to bubble through a solution of an alkaline hydrate, the sulphur and oxygen exchange places, with the formation of a sulphydrate. KOH + H2S = KSH + H20. When it is passed through a solution of a metallic salt, it forms, ln many instances, a sulphide of the metal. CuS04 -)- H2S = CuS -f. H2S04. It is, on this account, largely used in the labor- atory as a reagent for the separation of the metals from one another. Minute quantities of H2S may be detected by its odor, °r by the brown or black color it imparts to a paper moistened with a solution of plumbic acetate. Its principal use is as a reagent. 165. Physiological.—When inhaled, it is not an irritant, but a narcotic poison, even when largely diluted with air. According to Faraday, birds die in air containing rsW of it, and dogs in one containing According to Letheby, human beings cannot bve in an atmosphere containing more than one per cent. Its action is principally a reducing one upon the haemoglobin of the blood, and prevents this fluid from absorbing oxygen, although it probably does not combine with it. (Wurtz.) Hydrosulphuric acid is formed in the intestine, from the decomposition of albu- minous matters, especially where there is any impediment to digestion, or to the onward movement of their contents. It also sometimes occurs in abscesses, in the urine and bladder. This gas is almost a constant ingredient in the gas of sewers and privy vaults, existing free or combined with ammonium as ammonium sulphydrate. Poisoning by this gas may be acute or chronic. The latter is more common, producing a febrile state, with malaise and general debility. The injurious effects of sewer gas are partially due to this form of poisoning, although not entirely. Occasionally this gas is so concentrated in sewers that those who enter them suffer with acute poisoning, hill almost instantly, and if not rescued, die in a short time. I he treatment, in such cases, should consist in pure air, or oxygen, with brandy and water. Chlorine water, or a mixture of potassium chlorate and dilute hydrochloric acid, may be administered inter- 2H2S + 302 — 2H20 + 2S02. 124 INORGANIC CHEMISTRY. nally. Taken internally, in the form of natural mineral water, it is a favorite and popular remedy for rheumatism, gout, and certain skin diseases. 166. Sulphur and Oxygen.—The following oxides and oxacids of sulphur are known :— Hyposulphurous oxide, S 2 0 s. “ acid, H2S02. Sulphurous oxide, S02. “ acid, H2S03. Salts of Thiosulphuric acid, H2S203 Acid not isolated. Sulphuric oxide, S03. Sulphuric acid, H2S04. Sulphuric peroxide, S207 Nordhausen “ acid, H2S207. Salts of Dithionic acid, H202S02—S02. “ “ Trithionic acid, H2 = 02 = S02—S—S02. “ “ Tetrathionic acid, H202 == S02—S—S—S02. “ “ Pentathionic acid, H2=02=S02—S—S—S— S02 A few only of this large number of compounds are of sufficient importance to be described here. 167. Sulphurous Oxide or Anhydride, S02—Prepara- tion.—1. It may be prepared by burning sulphur in the air. 2. By heating sulphuric acid with copper turnings, sulphur, or carbon. According to the U. S. P., and B. P., charcoal is used. 168. Properties—Physical.—Colorless gas, having a pun- gent, suffocating odor, and a disagreeable acid taste. It is very soluble in water, with which it combines to form an unstable acid, emitting the odor of the gas, acidum sulphurosum, U. S. P. It is very soluble in alcohol. Sp. gr. 1.035. The density of the gas is 32.25; sp. gr. (Air = 1) 2.234.' Below —10° C. (14° F.), it is a colorless mobile liquid, which solidifies at —75° C. (—103° F.). Chemical.—Non-combustible, and will not support combus- tion or respiration. It combines with water to form sulphurous acid, and hence is an anhydride. Nascent hydrogen reduces it to H2S and water. It is a valuable reducing agent, easily taking up oxygen to form sulphuric anhydride or acid. It is a bleaching, disinfecting and deodorizing agent of considerable value. It bleaches many vegetable colors, although not perma- nently destroying them. The colors may be restored by an alkali, or weak chlorine water. It is used principally for straw, silk and woolen goods. It decomposes hydrogen sulphide, and, when concentrated, destroys many forms of microscopic life. SULPHUR. 125 169. Physiological and Medical Effects.—Used inter- nally, and as sulphites and thiosulphates (Hyposulphites) in zymotic diseases, gastric fermentations, sarcina, etc., also locally, in erysipelas and poisoned wounds. The sulphites and thiosul- phates of the alkaline metals are used for the same indications as the acid. Hyposulphite of sodium is prepared by digesting sul- phur with sulphite of sodiun. It is used in photography and electro-metallurgy, as a solvent for the silver salts. Dose of the acid, 4 c.c. (f3j) largely diluted. Dose of sulphite or hyposul- snlphite, 0.650 to 3.000 (gr. x to 1.) 170. Sulphuric anhydride (S03), is obtained by distilling Nordhausen acid, as white silky prisms, hissing when dropped upon water, from the energy with which they combine. Melts at 18.3° C. (65°F.), and boils at 43° C. (110° F.) Does not redden dry litmus paper. 171. Sulphuric Acid, Hydrogen Sulphate, Oil of Vitriol, H2S04 = 98.—The commercial acid is prepared in large quantities directly from sulphur or iron pyrites. The pro- cess is conducted in large chambers lined with sheet lead. Into these chambers sulphurous oxide is poured from a furnace in which sulphur is burned or pyrites roasted, along with a free supply of air. In the same furnace is placed a crucible con- taining sodium nitrate and sulphuric acid, for the purpose of Preparing and volatilizing nitric acid, which is carried into the chamber with the S02 and air. The nitric acid gives up a part °t its oxygen to oxidize a portion of the S02 to S03. 2HN03 + 3S02 = 3S03 + H20 + N202. The S03 then combines with the water thus produced, and KJore water is supplied by a jet of steam thrown constantly into the chamber. The N202 has the power of taking up oxygen from the air and becoming N204, which in turn parts with this oxygen to oxidize a new quantity N202 ~f- 02 = N204, N204 + 2S02 = N202 +2SO3. Thus the process is kept up as long as the S02, air, steam and are supplied. The acid condenses with the water on the floor °f the chambers, and when it reaches a sp. gr. of 1.55 it is drawn off into large leaden pans and evaporated to a sp. gr. of 1.746, when it begins to dissolve the lead. It is then drawn off into platinum stills and the concentration completed. 126 INORGANIC CHEMISTRY. 172. Properties.—The commercial acid is a heavy, corrosive, oily liquid, often of a brownish tinge, and has a sp. gr. of 1.830 to 1.845. It mixes with water in all proportions, combining with a certain quantity to produce H4S05, and finally ortho-sul- phuric acid, H6SOfi, with the production of considerable heat. The concentrated acid attracts moisture, and is used as a dessic- cating agent. Gases, allowed to bubble through it, are deprived of their moisture. It chars organic matter and corrodes animal tissues. Paper dipped in a cooled mixture of two parts of the acid and one of water, and then quickly washed, is con- verted into parchment paper. Starch or cellulose, when boiled with the dilute acid, is changed, by hydration, into glucose or grape sugar ; and cane sugar into glucose and levulose. In this action it behaves like the unorganized ferments, diastase, pepsin, trypsin, etc., and illustrates the so-called catalytic action of certain bodies. The dilute acid is a solution of H6S06 in water. On boiling this with the above bodies, it imparts a portion of its water to the organic body, and takes up more water from the solution to supply its place. Sulphuric acid is a powerful dibasic acid, forming a series of salts called sulphates, all con- taining the S04 group of atoms. It also forms a series of acid sulphates,—HKS04, HNaS04. Owing to the powerful affinities of this acid, it usually removes the metal or positive radical from other acids and sets them free. This should be remembered in adding it to prescriptions. It forms insoluble precipitates with solutions of barium, lead, strontium and with calcium in concen- trated solutions. The other sulphates are soluble in whter. 173. Medical Effects.—When dilute, tonic, astringent and refrigerant. Concentrated, or in large doses, it is a corrosive poison. Antidote—lime, magnesia, sodium carbonate, or other al- kaline body, best given in milk. 174. Officinal Forms.—Acidum sulphuricum, the so- called C. P. acid, of sp. gr. 1.84, used only in the making of other preparations. Acidum sulphuricum dilutum, sp. gr. 1.082, U. S. P., containing 11.9 per cent., H2S04. Sp. gr. 1.094 B. P. containing 13 per cent. H2S04. Acidum sulphuricum aromaticum, containing about the same amount of II2S04 as the dilute acid. 175. Tests and Impurities.—Commercial sulphuric acid always contains lead sulphate, producing a cloudiness when di- luted with water. Oxides of nitrogen, and sulphurous acid are also frequently found. A solution of brucia, with which they give a rose-red color, may be used as a test for the first. Or- SULPHUR. 127 ganic matter gives to the acid a dark color. Arsenic and iron are sometimes found in the commercial acid. The C. P. acid should not contain lead, iron or organic matter. It often contains oxides of nitrogen and sulphurous acid. Sul- phuric acid and soluble sulphates are easily detected by the use of barium chloride, or nitrate, with which they form a white Precipitate insoluble in hydrochloric acid. Lead, silver and mercury must first be removed with H2S, and the solution diluted. 176. Fuming Sulphuric Acid—Nordhausen Acid (H2S207), is obtained by distilling ferrous sulphate. The first portions are a white crystalline solid, fusing at 35° C. (95° F.), having the above composition. The commercial acid is a brown, oily liquid, fuming in the air, and hissing when dropped into water. Some chemists regard it as a solution of S03 in H2S04. When heated, it gives off S03 and H2S04. • It is used in manufacturing alizarine, eosin, etc., and as a sol- vent of indigo. It forms a series of salts called disulphates. 177. Sulphur with Chlorine, Bromine and Iodine— Sulphurous Chloride (S2C12).—A yellow, volatile, fuming liquid, formed by distilling sulphur in an atmosphere of chlorine gas, and having a powerful solvent power for sulphur and sul- phuric chloride. It is decomposed by water, but mixes with benzol and carbon disulphide. SC12, and several oxychlorides, are known. Bro- mine unites directly with sulphur to form a red, unstable liquid, Probably consisting mostly of S2Br2. Iodine and Sulphur combine directly when gently heated, even under water. When 127 parts of iodine and 32 parts of sulphur are heated they form a steel-gray crystalline mass, S2I2, Suiphuris iodidum (U. S. P. and B. P.), said to be a pow- erful remedy in certain skin diseases. It melts at 60° C. (140° F.), und is insoluble in water. Other iodides have been described, but are unimportant. h2s2o7 = h2so4 + so3. SELENIUM AND TELLURIUM. Se. 79.5. Te. 128. 178. These elements are rare and of no special interest to the physician. 128 INORGANIC CHEMISTRY. NITROGEN GROUP. Nitrogen, N = 14 III or V. Phosphorus, P = 31 III or Y. Arsenic, As = 75 III or V. Antimony, Sb =122 III or Y. Bismuth, Bi = 210 III or V. 179. Group Characteristics.—A well defined group with nitrogen at the negative end and bismuth at the positive. The atomic weights form a graded series from 14 to 210. The first is a gas ; the second a volatile solid ; the third a volatile, crystal- line, metallic-looking body, showing a slight tendency to alloy with metals and combine with acids; the fourth less easily volatil- ized, crystalline, possessing a brilliant lustre, alloying with metals, and showing a tendency to act the positive role with acids ; the fifth, also crystalline, having a metallic lustre, and showing more marked positive tendencies. They are all both triad and pentad, and form two series of compounds. The following will exhibit the relations of some of the most important compounds:— Hydrides. Chlorides. Oxides. Sulphides. nh3 nci3 ... n2o3, n2o5 •PH3 PCla, PC15 P203, P205 P2S3, P2S5 AsH3 AsC13, AsC15 As203, As205 As2S3, As2S5 SbH3 SbCl3, SbCl5 Sb203, Sb205 Sb2S3, Sb2S5 BiCl3, ... Bi203, Bi205 NITROGEN. Symbol, N. At. wt. 14. Equivalence, I, III or V. Density, 14. Wt. of 1 litre, 1.256 grins. Sp. gr., (Air = 1) 0.971. 180. Occurrence.—Exists free in air, mixed with oxygen. It is also found free in the gases found in the stomach, large and small intestine, the urine, etc. Combined, it occurs as nitrates of potassium, sodium and calcium, in ammonia, and in many vege- table and animal bodies of the proteid group. 181. Preparation.—From the air, by burning phosphorus in a confined space until the oxygen is removed, or by passing air over copper or iron turnings heated to redness, the nitrogen pre- pared by both these methods contains small quantities of other gases found in the air. To prepare it pure, heat ammonium nitrite (NH4N02). 182. Properties —Physical.—A colorless, transparent,odor- less, tasteless, incombustible gas, not a supporter of combustion or THE ATMOSPHERE. 129 of animal respiration. It is not poisonous ; very sparingly solu- ble in water or alcohol. One part of water dissolves, at the ordi- nary temperature and pressure .025 parts of this gas. Chemi- cally, nitrogen is characterized by its inertness. It unites directly with magnesium, boron, vanadium and titanium. Indirectly, it forms a great number and variety of compounds, many of which are unstable. Under the influence of electric discharges nitrogen can be caused to unite with hydrogen to form ammonia, NH3, and with oxygen to form nitrous and nitric oxides. From this source most of the nitrogenous products necessary to sustain plant life are primarily derived. 183. The atmosphere is composed principally of nitrogen and oxygen mixed together in the proportion of 20.93 parts of oxygen by volume to 79.07. parts of nitrogen, and, by weight, 23 parts of oxygen to 77 parts of nitrogen. Although air is a mixture and not a definite compound, it is remarkably constant in composition. Regnault found in 233 analyses of air, at different times and places, that the per cent, of pxygen by volume varied between 20.908 and 20.999. That air ls a mixture is proved by : 1st, its gases are not present in the Proportion of their atomic weights; 2d, air can be made, to answer all the properties of the atmosphere, by a mechanical mixture °f the gases; 3d, solvents for oxygen, as an alkaline solution °f pyrogallic acid, remove this gas from the air; 4th, each gas dissolves in water independently of the other, and with its own solubility; thus, by expelling the air from water, by boiling, and analyzing it, we find it to correspond to that calculated from the known solubility of the two gases. fhe analysis of the air expelled from water contains 33 per cent, of oxygen, and 67 per cent, of nitrogen; it is, therefore, *ouch richer in oxygen than the atmosphere. Owing to the rapid diffusion of the gases, the disturbances in composition due to the respiration of animals and manufacturing processes, are soon re- stored. Besides the two chief gases found in the air, there are various other ingredients found in small quantities; as water vapor, carbon dioxide, ozone, ammonia, nitric and nitrous acids, hydrocarbons, solid particles of dust, sodium chloride, vegetable germs or spores, bacteria, etc. Air in which animals are con- fined, also contains some of the organic exhalations from their bodies. In the neighborhood of large cities, various other sub- stances are poured into the air from manufacturing establishments. THE ATMOSPHERE. 130 INORGANIC CHEMISTRY. The essential ingredients are oxygen, nitrogen, carbon di- oxide, and watery vapor. The rest of those enumerated, may be regarded as accidental, and not essential to the growth of plants and animals. 184. Watery Vapor.—The proportion of watery vapor in the air varies considerably with the temperature and locality. The air is seldom saturated in the daytime, and contains less inland than near large bodies of water. The higher the temper- ature of the air the more moisture it will hold; thus, at 0°C. (32°F.), 1 cu. metre (1.3 cubic yards) is saturated by 5.4 grammes (83.3 grs.) of water, and at 25°C. (77°F.), the ordinary temper- ature, it requires 22.5 grammes (347 grs.). Or, at 77°F., one cubic yard will be saturated by 267 grains of water, and one cubic foot by about 10 grs. In reality, the air will seldom be found to contain more than 60 or 70 per cent, of this amount. When one cubic metre (1.3 cu. yds.) of an atmosphere, saturated at 25°C. (77°F.), is cooled down to 0°C. (32F.), it will deposit as dew, rain, or frost, 22.5 — 5.4 = 17.1 gins. (263.8 grs.). The temperature at which air begins to deposit its moisture, on being cooled, is called the dew point. The dew point will depend upon the amount of water actually present in the air. The amount of moisture is determined by passing a known volume of air through tubes containing calcium chloride, which absorbs the water. The increase in the weight of the tube gives the weight of water. The amount of vapor in air varies from .3 to 1.6 per cent, by volume. The dampness of the air does not depend upon the amount of water it contains, but upon the degree of saturation. A cold damp air, when heated, becomes dry; hence, the neces- sity of supplying moisture to the heated air in our rooms in winter. A very dry air irritates the air passages, produces dryness of the skin and malaise. A very moist atmosphere checks evaporation from the skin and lungs, raises the bodily temperature, and soon becomes oppressive. 185. Carbon Dioxide.—The average amount of carbon di- oxide, C02, in country air is 4 parts in 10,000, and varies from 3 to 6 parts. It is greatest near large cities and manufactories, greater during the night than the day, on land, and the reverse on the ocean. Plants remove it from the air in the daytime, and the cooler water at night, more than the warmer water during the day. (See Carbon dioxide.) 186. Ammonia.—This exists in the air, in very minute quantities, in the form of carbonate, nitrate and nitrite, the result of the decomposition of animal and vegetable organic matters. 131 It is especially evolved from urinals, privy vaults and horse stables. It is washed out of the air by falling rain, and is taken up from the soil by plants. 187. Nitric and Nitrous Acids occur in extremely minute quantities, and are produced by the direct union of oxygen and nitrogen in the presence of watery vapor, under the influence of discharges of lightning. They exist principally in combination with ammonia. Hydrocarbons, the principal of which is marsh gas, are fre- quently found in the air of cities, coal mines, wells and swampy districts. It is produced by the decomposition of vegetable matter under water, and in some industrial processes. 188. Accidental Gases in the Air.—The gases generated in certain manufactures are sometimes allowed to escape into the air from the rooms in which workmen are employed. Some of these are harmless and others hurtful. Among the first class may be mentioned carbon dioxide, when not in too large quanti- ties, and ammonia. To the second class belong hydric sul- phide, ammonium sulphydrate, sulphurous oxide in large quantities, vapors of mineral acids, carbon disul- phide, etc. Hydric Sulphide, or Sulphuretted Hydrogen, is found in certain tunnels and mines, caused by the decomposition of iron Pyrites. It is also found in the air of some marshes and sewers. The symptoms produced by breathing small quantities of this gas, are those of debility and anaemia ; in larger quantities, head- ache, vertigo, weak pulse, sweating and prostration. Sulphydrate of Ammonia produces nearly the same symp- toms as hydric sulphide. It occurs in the air of sewers and privy vaults. Both these substances are easily destroyed by chlorine or sulphurous oxide. Sulphurous Oxide, unless in considerable quantities, and in a closed room, does not seem to have any deleterious effect upon the workmen. In bleachers it sometimes produces irritation of the bronchial tubes. Hydrochloric Acid, Nitric Acid, and Chlorine in con- siderable quantities are very irritating to the lungs and conjunc- tiva. Carbon Disulphide produces unpleasant and deleterious effects upon workmen exposed to air containing it; as headache, giddiness, nervous depression and loss of appetite. 189. Suspended Matters.—A great variety of solid par- ticles, or dust, are found in the air at all times. These consist of fragments of wood, textile fabrics, metals, etc., pollen of plants, THE ATMOSPHERE. 132 INORGANIC CHEMISTRY. bacteria germs, etc. These suspended particles may be regarded as impurities, and many of them are injurious to health. Work- men in various trades are seriously affected by the dust to which they are exposed ; as miners, especially of lead and coal, grinders of metals, wool sorters, rag pickers, feather dressers, etc. The irritation of the dust of these and other trades may cause chronic bronchitis, emphysema, phthisis, or chronic poisoning. Germs of various kinds are believed to cause many of the conta- gious and malarial diseases, and may be carried some distance in the air. Some of these germs seem to be easily oxidized, while others are very persistent. The best disinfectants for their de- struction, are free ventilation and consequent dilution, chlorine, bromine, iodine and sulphurous oxide. 190. Disinfectants, Germicides,* Antiseptics, Deodor- izers.— The presence of odors and organized “ germs ” in the air, often require the use of one of the above agents. Disinfectants are a class of bodies which are supposed to destroy the germs, and thus prevent them from causing their specific action either upon the human body or in decomposable organic bodies or solutions. The most efficient of these is heat. Organized germs may be filtered from the air by passing it through cotton wool; or they may be removed by inclosing the air in an air-tight box or chamber, the insides of which are moistened with glycerine. (Tyndal.) Ozone, chlorine, bromine, iodine, sulphurous oxide, mercuric, zinc, aluminium, magnesium and calcium chlorides, potassium chlorate, potassium permanganate, carbolic, boric, cresylic and sulphuric acids, thymol, menthol, camphor, etc., are among the disinfectants most used. Antiseptics are agents which retard or entirely prevent putrefaction or growth of microscopic germs and organisms. While disinfectants destroy the cause of infection, anti- septics prevent the development of these causes. Low tem- perature retards putrefaction, and is, therefore, an antiseptic agent. These two terms are frequently used interchangeably. Asepsis is a condition of entire absence of any germs or cause of infection. Deodorizers are bodies used to destroy offensive odors. They may be either solid, liquid or gaseous. Solids— dry earth, lime, charcoal, ferrous sulphate, carbolates of calcium, sodium and magnesium. Liquids—solutions of plumbic nitrate * A germicide is an agent which has the power of killing the germs, and thus preventing their growth. A disinfectant destroys the infectious properties of a septic matter, whether this be due to germs or some other agent. THE ATMOSPHERE. 133 (Ledoyen’s fluid), zinc chloride (Burnett’s fluid), potassium or sodium permanganate (Condy’s fluid), a mixture of copper and zinc sulphates (Lanande’s disinfectant), solutions of ferric chlo- ride, of ferrous sulphate, hypochlorites, etc., are among the best known. Gases—pure air, ozone, chlorine, bromine, and sul- phurous oxide are those most effective. Fumigations with tar, kerbs, and various aromatic substances, only disguise the offen- sive odors, but do not destroy them. The ordinary offensive odors are due to hydric sulphide (H2S), ammonium sulphhydrate (NH4HS), phosphoric hyuride (PH3), and complex ammonium compounds. Chlorine, ozone, and ni- trous oxides will destroy these gases by oxidation, and thus destroy the odor. It should be remembered that these odors, in themselves, may not be in any degree injurious to health, when in small quantity, but they serve to warn us of the presence of other products of putrefaction which accom- pany them, and which are injurious. The fact that efficient disinfection of the air can prevent the spread of the contagion of disease is well known. Chlorine and sulphurous oxide are the two agents most in use, and of these the former is very much to be preferred, but the latter is used for furnished rooms, because of its less destructive action on articles exposed to it. It is doubtful whether organized germs can be destroyed in the air by any disinfectants, except in tightly closed rooms. The attempt to disinfect the air of rooms with the various so:called “disinfectants” of the market 18 worse than useless. It engenders a feeling of security where there is uone. These floating germs can certainly stand as much, and in most puses, more than man, and therefore, no room can be disinfected while !t is occupied by human beings. The author has found by experiment, that most of the ordinary antiseptics, when diffused through the air of an ordinary room, are almost without action on putrefactive bacteria, unless fue quantity be great enough to make the air irrespirable. The following table shows the amount of water it is necessary to add to one part of the substance named, which barely permits Ike development of bacteria in meat infusions, according to M. Jalan de la Croix:— Water, 1 Part. Parts. Alcohol 30 Chloroform 134 Borax 107 Eucalyptol 308 Phenol (Carbolic acid) 1,002 fhymol 2,229 Potass, permanganate 3,041 Picric acid 3,041 Borated sodium salicylate 3,377 Benzoic acid 4,020 Water, 1 Part. Parts. Oil of mustard 5,734 Sulphurous acid 7,534 Aluminium acetate 7,535 Salicylic acid 7,677 Mercuric chloride 8,358 Calcium hypochlorite 13,092 Sulphuric acid 16,782 Iodine 20,020 Bromine 20,875 Chlorine 34,509 134 INORGANIC CHEMISTRY. Devaine says of iodine, that 1 part to 12,000 destroys the con- tagion of charbon,and 1 to 10,000 of septic blood. Billroth says mercuric chloride 1 to 20,000, thymol and benzoate of sodium 1 to 2000, and benzoic acid and creasote 1 to 1000, prevent the de- velopment of bacteria. Koch says of mercuric chloride, 1 to 15,000 kills most micro-organisms, and 1 to 1000 destroys resting spores. The results of different experimenters are so widely discordant, that we make no attempt to reconcile them. The following table represents tTie results of experiments upon commercial disin- fectants. The first column gives the per cent, of the agent ne- cessary to kill anthrax and bacillus subtilis. The second gives the per cent, of the agent which failed to produce this result. NAME. Per cent, in, when active in two hours. Per cent, in, which failed in two hours. Little’s Soluble Phenyle 2 1 Labarraque’s Solution (U. S. P. 7 5 Liquor Zinci Chloridi (Squibb’s) 10 7 Feuchtwagner’s Disinfectant Labarraque’s Sol. (Frer6, Paris) 10 8 15 10 Phenol Sodique 15 10 Platt’s Chlorides 20 15 Gerondin Disinfectant 25 15 Williamson’s Sanitary Fluid 25 20 Bromo-chloralum 25 20 Blackman’s Disinfectant 80 20 Squibb’s Impure Carbolic Acid 50 Bouchardat’s Disinfectant 50 Phenol Sodique (Paris) 50 Listerine 60 Hypochlorite of Sodium or Calcium. Available Chlorine 0.25 list of commercial disinfectants (Sternberg). NITROGEN AND HYDROGEN. Ammonia. NHS = 14 + 3 = 17. Density = 8.5. Sp. gr. .59. 191. Source.—From the decomposition of animal or vegetable matter containing nitrogen, either spontaneously, or by the aid of heat. First prepared by distilling camels’ dung, in Libya, near the temple of Jupiter Ammon. When horns, clippings of hides, or coal are heated in closed retorts, ammonia is given off. The principal source, at present, is from the ammoniacal liquors of gas works. Coal contains about 2 per cent, of nitrogen, which NITROGEN AND HYDROGEN. 135 is mostly given off as ammonia. The ammonia liquor is treated with hydrochloric acid, and evaporated to dryness, when an im- pure ammonium chloride, sal-ammoniac, is obtained. This may be purified by recrystallization or sublimation. This salt, heated with lime (CaO) gives off its ammonia. This is conducted through a series of Woulfe bottles containing water, in which the gas dis- solves, forming aqua ammonia, from which the other compounds niay be prepared. 2NH4C1 + CaO = 2NH3 + H20 + CaCl2. 192. Properties.—A colorless, transparent, pungent, irre- spirable gas. Does not support combustion or burn in air, but burns with difficulty in an atmosphere of oxygen, forming water and free nitrogen. It has a strong alkaline reaction on moistened litmus paper, which, however, is not permanent, owing to the volatility of the ammonia. It is lighter than air. Liquefies at —40°C. (—40°F.); or at 10°C. (50°F.), under a pressure of 6.5 atmospheres, to a color- less liquid of specific gravity 0.76, which solidifies at —75° C. (—103°F.). It is very soluble in water; one volume of water at 15°C. (59°F.) dissolves 783 volumes of the gas with the evolution ■ of heat, forming the solution known as aqua ammonise or liquor ammoniae, which may be regarded as a solution of am- monium hydrate, NH4-0-H. This solution, on being heated, gives up most of the gas again. Aqua ammoniae fortuor (U. S. P.) contains 28 per cent., by weight, of the gas, and has a sp. gr. of 0.900 at 15°C. (59°F.). Aqua ammoniae (U. S.P.) contains 10 per cent, by weight, and bas a sp. gr. 0.959 at 15°C. (59°F.) It is a colorless, transparent liquid, with a pungent odor, and alkaline taste and reaction. It forms, by direct union with the acids, a series of salts containing the compound radical NH4, called ammonium. Ammonia is vola- tile, and hence it is sometimes known as the volatile alkali. The compounds of NH4 closely resemble those of Na and K, and will be considered with them. The strong solutions of the gas act as a caustic upon animal tissues, and are, therefore, corrosive poisons. 193. Composition.—This may be determined by decom- posing the gas by passing a series of electric sparks through a quantity of it inclosed in a eudiometer tube over mercury. The volume increases until double the original volume is reached. By introducing a quantity of oxygen equal to that of the am- 136 INORGANIC CHEMISTRY. monia used, and igniting the gases by the same spark, the hy- drogen and oxygen combine, and after condensing leave the nitrogen, which occupies one-half the original volume, or one- fourth the volume of the mixed hydrogen and nitrogen after the decomposition. It is thus shown to be composed of one-fourth nitrogen and three-fourths hydrogen. We may also arrive at the same result in the following manner:— Prepare a glass tube of about 1 c.c. Q in.) calibre, closed at one end ; through the stopper in the open end pass a funnel tube drawn to a point and provided with a stop-cock. Fill the tube with pure dry chlorine, and in- sert the cork. Fill the funnel tube with strong ammonium hydrate solu- tion, open the stop-cock, and allow a portion of the liquid to enter the tube. The chlorine decomposes the ammonia gas, combining with its own volume of hydrogen and setting free the nitrogen in combination with it. By removing the stopper under water, the water will rise to fill the tube, excepting that portion occupied by the nitrogen, which will be found to be one-third of the whole tube. Now, as the chlorine combined with its own volume of hydro- gen, or with the tube full, and left one-third of that volume of nitrogen, it is easy to see that the ammonia was composed of three parts by volume of hydrogen, and one part of nitrogen. Since gaseous molecules all occupy the same space, three mole- cules of hydrogen and one of nitrogen form two of ammonia: 3H2 + N2 = 2NH3. The compounds of ammonium with acids will be considered under the head of salts of alkaline metals. 194. Tests.—Smell. Fumes with HC1. Moistened red litmus paper is changed to blue by it. Nessler’s test, see Art. 125. 195. Hydroxyl Amine (NH30 or Nh_h).—This compound, closely related to ammonia, may be regarded as a molecule of ammonia in which one hydrogen atom has been replaced by the hydroxyl radical. Prepared by treating tin with dilute nitric acid, or a mixture of this acid and hydrochloric acid. The nascent hydrogen generated, reduces the acid and forms the above compound, which combines directly with the remaining free acid. HN03 + BH2 = H3NO + 2H20 H:tNO -f HC1 = NH20H. HC1 Hydroxyl Amine. Hydrochloride of Hydroxyl Amine. It is an unstable liquid, not obtainable in a free state, and possesses decided basic properties—blues reddened litmus paper, and combines directly with acids to form salts. NITROGEN AND HYDROGEN. 137 196. Nitrogen Chloride (NC13).—When chlorine, in ex- cess, is made to act upon ammonia, or a solution of ammonium chloride, the chlorine at first sets free nitrogen, and forms am- monium chloride; the excess of chlorine then acts upon the ammonium chloride, to form nitrogen chloride. NH4C1 + 3C12 = NC13 + 4HC1. 197. Properties.—A yellow, oily liquid, insoluble in water, possessing a disagreeable, irritating odor. Sp. gr. = 1.653. It is very explosive, and in contact with any combustible matter, explodes spontaneously. It should not be prepared in large quantity. 198. Nitrogen Iodide (NHI2 or NI;j). Preparation.— Fy lightly triturating iodine, in a mortar, with strong ammonium hydrate, or by pouring an alcoholic solution of iodine into strong ammonia water. 199. Properties.—A brownish-black solid,insoluble in water, which, when spread out on filter paper and dried, explodes with the slightest touch, or by a gentle breeze; the explosion, how- ever, is not nearly so violent as that of the chlorine compound. 200. Nitrogen and Oxygen.—Five oxides of nitrogen are known, whose names, graphic formulae and corresponding acids are as follows:— Nitrous Oxide X—0—N Hyponitrous Acid II—0—N Oxide 0=N XXO Witrous Anhydride 0_X—0—X_0 Nitrous Acid... H—0—X_0 JS=n-o-n=o oTZS&Sdt i I Nitric Acid H-0-N=g 201. Hyponitrous Oxide. Nitrous Oxide, Laughing- gas. Nitrogen Monoxide. Nitrogen Protoxide (N20).— Discovered in 1776, by Priestly. Anaesthetic effect first dis- covered by Sir Humphrey Davy. First used in dentistry by Wells, of Hartford, Ct. First came into notice as an anaesthetic in 1863. 202. Preparation.—By gently heating ammonium nitrate, when it decomposes into hyponitrous oxide and water. NH4N03 = N20'+ 2H20. For anaesthetic purposes, care should be exercised to keep the temperature of the retort between 210°C. (410°F.) and 250°C. (482°F.), as below the former the decomposition does not take place, but the salt sublimes; while above the latter, nitrogen di- oxide and trioxide are generated. As an additional safeguard, G* 138 INORGANIC CHEMISTRY. the gas should be caused to bubble through solutions of sodium hydrate and ferrous sulphate, to remove these higher oxides. 203. Properties.—A colorless, odorless, sweetish-tasting gas, slightly soluble in water, more so in alcohol. Density 22. Sp. gr. 1.527. Under a pressure of 50 atmospheres at 7CC. (45°F.) it condenses to a colorless liquid, which resumes the gaseous state as soon as the pressure is removed, the temperature sinking so low as to freeze a portion of the liquid into a white, snow-like solid. Sp. gr. of liquid 0.908. Boiling point —88°C. (—126°F.) Freezing point about —101°C. (—150°F.) It is neutral in reaction, i. e., neither acid nor alkaline. It supports the combustion of bodies, very much like oxygen; this is due to the fact that the heat of the burning bodies decomposes the gas, giving an atmosphere about them containing twice as much oxygen as ordinary air. For anaesthetic purposes, the liquefied gas is now sold in wrought-iron cylinders, provided with a stop- cock, so that the gas can be drawn from the cylinder as needed. 204. Physiological Effects.—Nitrous oxide causes, when first inhaled, an exhilaration, then anaesthesia, and finally, as- phyxia. It will not support the respiration of plants or animals. It seems to act partly by excluding air, and partly by its direct effect upon the nervous system, but does not enter into any chemi- cal combination in the blood; it simply dissolves in this fluid. When mixed with oxygen, and administered under an increased pressure, the anaesthesia may be kept up for a long time with safety. Deaths from its inhalation are rare. It does not undergo decomposition in the blood. It is much used for short operations, and especially for the extraction of teeth, opening abscesses, felons, etc. Recovery is prompt and complete within a few minutes after its withdrawal. A solution in water, containing five volumes of the gas, has been administered internally. 205. Hyponitrous Acid (HNO).—This acid may be pre- pared by the action of hydrochloric acid on the silver salt. The potassium salt (KON) is formed by the action of sodium amalgam on potassium nitrite or nitrate; preferably the former: K0N02 + 2H2 = KON + 2H20. The silver salt is a yellow, almost insoluble powder. 206. Nitric Oxide or Nitrogen Dioxide. NO or N202.— Prepared by the action of nitric acid upon copper. 3Cu -}* 8HN03 — 3Cu (N03)2 -f- N202 + 4H20. 207. Properties.—A colorless, transparent gas, very sparingly soluble in water, more soluble in alcohol. Density 15, sp. gr. 1.039. NITROGEN AND HYDROGEN. 139 The density would make the molecular weight 30, and the formula NO, which is anomalous, as in this case nitrogen must be considered as a dyad. The ordinary laws of valence would make it N202. It is probable that at lower temperatures this is the proper formula, and at the higher temperature dissociation takes place; N202 splitting up into NO, NO, as has been proven to occur in the case of N204. By cold and pressure, the gas has been reduced to a liquid. Bodies which evolve considerable heat in burning, as, for ex- ample, phosphorus, burn in this gas; first decomposing it, and then uniting with its oxygen. In contact with free oxygen, or air, it takes up this gas and is converted into N.204, or N.203, ac- cording to the amount of oxygen present. In both cases it gives a reddish-brown colored gas. A test for free oxygen. It is rap- idly absorbed by a solution of ferrous sulphate, to which it im- parts a deep brown color. Its action on the economy is not known. It forms no corresponding acid. 208. Nitrous Anhydride (N203).—Prepared by the direct union of nitric oxide (NO) and oxygen, mixed in the proportion of four of the former to one of the latter. Also, by warming nitric acid with starch, or arsenious acid, and by the action of the peroxide on cold water. 2N204 + H20 = N203 + HN03. 209. Properties.—A dark blue liquid, boiling at 0°C. (32°F.), with partial decomposition into NO and N204 which recombine on cooling. It combines directly with water, producing nitrous acid (HN02), which, on warming, decomposes into nitric acid and nitric oxide. 3HN02 = HN03 + 2N0 + H20. As will be seen from the above, this oxide is very unstable. 210. Nitrous Acids and Nitrites.—The acid is not known iu a pure state, but several of its salts are known. The nitrites are formed by heating the nitrates, when they give off a part of their oxygen. The action is rendered easier, if lead or some other oxidizable metal be added to the fusion. The nitrites are pro- duced in nature, by the oxidation of nitrogenous organic matter, accompanied by certain forms of microscopic life. Such nitrifi- cation takes place in waters polluted with organic matter, and normally in the soil. The acid then combines with bases found in the water or soil. The presence of nitrites in water, is, for this reason, looked upon as an evidence of previous contamina- tion with nitrogenous matter. Further oxidation leads to the formation of nitrates in the same circumstances. The addition 140 INORGANIC CHEMISTRY. of a dilute mineral acid to a nitrite sets free reddish-brown fumes of NO and N204. A solution of argentic nitrate forms a precipitate with cold, not too dilute, solutions of an alkaline nitrite. These two reactions distinguish these salts from the nitrates. The reddish fumes, above mentioned, are strong oxi- oxidizing agents, and set free iodine from potassium iodide. A solution of starch, with which iodine forms a deep blue color, and a solution of potassium iodide with dilute sulphuric acid, are used as a test for nitrites in solution. (Art. 122.) Nitrous acid and the nitrites act as reducing agents upon an acid solution of potassic permanganate, and decolorize this latter salt. The nitrites can be taken up by plants, and elabo- rated into their structure, and hence, are valuable fertilizers. 211. Nitrogen Peroxide, Nitrogen Tetroxide, Nitro- gen Dioxide (N204).—It may be prepared by mixing two volumes of nitric oxide with one of oxygen. 2N0 + 02 =N204. More easily, by heating dry plumbic nitrate in a retort, passing the vapors into a cooled receiver, where they condense into a liquid: Pb (N03)2 = PbO + n2o4. Composition.—N204 appears to exist in a pure state only at temperatures below 0°C. (32°F). The liquid is colorless at these temperatures, but at its boiling point is yellow in color, owing to partial dissociation into N02, which is complete at about 150°C. (302°F.) The gas is always reddish-brown in color, due to the presence of N02, while N204 is colorless. The density of the gas at 26°C. (78.8°F.) (the boiling point of the liquid), is 38, and contains 20 per cent, of N02. On raisingthe temperature, the density diminishes and finally becomes constant at 150°C (302°F.), and equals 23. This density corresponds to N02 = 46. This phenomena of dissociation is frequently noticed in determining the density of bodies at temperatures much above their boiling points. The laws of quantivalence seem to hold, in these cases, only at the lower tem- peratures at which dissociation does not take place ; hence, the confusion that exists in the formulae of such bodies as N204 or N02, N202 or NO, Hg2Cl2 or HgCl, etc. 212. Properties.—Cold water, in small quantity, decomposes it into N203 and HN03, while in larger quantities and with alkaline hydrates, it forms nitrous and nitric acids, or their salts. The tetroxide, N204, and the dioxide, N02, both act as strong oxidizing agents, setting iodine free from the iodides. 213. Nitric Anhydride and Acid.—N205 and HN03. Nitric Anhydride is a white crystalline solid, fusing at 30°C. (86°F.), and boiling at 47°C. (110.6°F.). Obtained by treating dry silver nitrate with chlorine, or by the removal of water from NITROGEN AND HYDROGEN. 141 fuming nitric acid by the action of phosphoric oxide (P205). The oxide is unstable, has a strong affinity for water, with which it forms nitric acid. It has no especial use or interest. 214. Nitric Acid — Aqua Fortis, or spirits of nitre (HNO,), is the most important of the acids of nitrogen. Does not occur free, but as nitrates widely disseminated. It is usually prepared, commercially, by the action of sulphuric acid upon Potassium or sodium nitrate, in glass or cast iron retorts. NaN03 + H2S04 — HNaS04 -f HN03. By the application of heat to the mixture, the HN03 distills over and is condensed in earthenware Woulfe bottles. It is also formed in small quantities by the passage of electric discharges through a mixture of nitrogen and oxygen. This takes place in the air by the passage of flashes of lightning, Probably by the oxidizing action of the ozone generated by these phenomena. The nitrates are formed in the soil and natural waters by the oxidation of organic matter, called nitrification, and is induced by certain microscopic organisms called the nitrifying ferment. In some localities the process is conducted artificially. (See Potassium Nitrate.) The commercial acid, prepared as above, contains sulphuric acid, traces of iron, brown nitrous oxides and chlorine. It is purified by redistillation with plumbic nitrate, which retains the impurities and allows the pure acid to distill over. 215. Properties.—The pure acid is a colorless, rather heavy, fuming liquid, having a sp. gr. of 1.52, boiling at 86°C. (186.8° B.), and solidifying at —40°C. (—40°F.). The sp. gr. and boiling-point of the weaker acid, vary with the proportion of acid present. When strongly heated, or on exposure to light and air, the acid is decomposed into nitric tetroxide (N204), water, and °xygen, and turns yellow. Nitric acid readily gives up a portion of its oxygen, and thus acts as a strong oxidizing agent, attacking and destroying vegetable and animal tissues and coloring matters. It is some- times used as a cauterizing agent, first producing a yellow stain, then destroying the tissue. While it oxidizes most organic bodies, it enters into the composition of others, forming substitu- tion products. Thus glycerine, cotton, sugar, etc., when treated with it form explosive substitution products. Most metals dis- solve in the acid, forming nitrates; gold and platinum are excep- tions. The non-metals or negative elements are usually oxidized by it. Metallic iron dissolves readily in the dilute, but when 142 INORGANIC CHEMISTRY. plunged into strong acid, it assumes a condition known as the passive state ; if now it be put into dilute acid, it is not attacked by it until a piece of platinum is brought in con- tact with it, or by some other means the passive condition is destroyed. Nitroso-nitric acid is a yellow, partially decom- posed acid, containing nitric peroxide (U204). Aqua regia is prepared by mixing together four parts of hydrochloric, and one of nitric acid; it soon assumes a yellowish-red color, and has the power to dissolve gold, platinum, and other metals, forming chlorides. Fuming Nitric Acid.—A reddish-brown acid. Sp. gr. 1.525. Containing N203 or N204. Used as a powerful oxidizing agent. 216. Officinal Forms.—Acidum Nitricum. Sp.gr.1.42; contains 69.4 per cent, of HN03. Acidum Nitricum Dilutum is prepared by adding six parts of distilled water to one of the above acid. Sp. gr. 1.059, and contains 10 per cent, of HN03. Used for internal adminis- tration. Dose ttl5-15. Acidum Nitro-hydrochloricum, or Nitro-muriaticum. Prepared by mixing 4 parts of acidum nitricum with 15 parts of acidum hydrochloricum. Acidum Nitro-hydrochloricum Dilutum; is made by adding 76 parts of water to the above formula for the strong acid (U. S. P. 1880). 217. Tests.—1. Add to suspected liquid some ferrous sul- phate, and pour the mixture on some strong sulphuric acid in a test tube. A black, brown, or reddish zone at the point of con- tact of the two liquids indicates nitric acid. (See Art. 207.) 2. Heat the suspected solution with some sulphuric acid faintly colored with indigo, when, if nitric acid or a nitrate be present, the blue color will disappear. 3. The strong acid imparts a deep red color to the alkaloid, brucine. 4. When heated with copper turnings, the liquid assumes a green color, and evolves reddish fumes. When the acid is in combination, a stronger acid must be added to set it free, as in test 2. 218. Physiological Effects.—In small quantities, well diluted, it is a stomachic tonic, and augments the secretion of urine. It seems to be mostly decomposed in the body, but a small quantity may pass into the urine as nitrates ; it acts, therefore, as an oxidizing agent. The strong acid is a corrosive, violent poison, first staining the tissues and vomit with which it comes in contact PHOSPHORUS. 143 a bright yellow color, and then corroding them. These stains will be found on the tongue and fauces in cases of poisoning by this acid. Antidote—milk of lime, magnesia, or other alkalies well diluted, followed by sustaining treatment. PHOSPHORUS. P = 31. Density of vapor = 62. Mol. wt. 124 = P4. 219. Occurrence.—Discovered by Brandt, in 1669, in urine ; and by Gahn, in bones, in 1769. Does not occur native, but as phosphates and in organic substances. Most common form is the calcium phosphate, (Ca3(P04)2), derived from bones of prehistoric mammals. 220. Preparation.—Phosphorus is usually prepared from the ash of burnt bones, in which it exists as tri-calcium phosphate, The ash is first converted into a soluble monocalcium phosphate, sometimes called superphosphate, by treating it with sulphuric acid. Ca3(P04)2 + 2H2S04 = CaH4(P04)2 + 2CaS04. The CaH4(P04)2 is dissolved in water, and drawn off, leaving the CaS04 in the vat. This solution is evaporated to dryness, after adding powdered charcoal, and then transferred to a retort, whose beak dips under water. The retorts are then gradually heated to a high temperature, when the CaH4(P04)2 is first de- hydrated and converted into calcic metaphosphate, Ca(P03)2, and water, and then undergoes reduction under the action of the carbon, as follows :— 4Ca(P03)2 +5C2 = P4 + 10CO + 2Ca2P207. The free phosphorus distills over and condenses under the water as an impure article, which is purified by redistillation; or by fusing it under water with sulphuric acid and potassium dichro- mate, and then casting it into sticks, in moulds. 221. Properties—Physical.—Phosphorus is met with in several distinct allotropic states. The ordinary form is a translucent, waxy-looking solid, which, at ordinary temperatures, is tenacious, and about the consistency of wax; but at 0°C. (32°F.) and below, it becomes brittle. It melts at 44°C. (111°F.) under water, and boils at 290°C. (554°F.) By the action of light, it soon becomes coated with a whitish or reddish coat, probably an oxide. The sp. gr. is 1.83 at 10°C. (50°F.) It shines in the dark, and when exposed to moist air, emits the odor of ozone. It is insoluble in water and alcohol, 144 INORGANIC CHEMISTRY. but soluble in ether, benzine, petroleum, and in the fixed 'and essential oils. The best solvent is carbon disulphide. From this solution, it separates in the form of octahedral and dodecahedral crystals. When a portion of the solution is poured upon filter paper and allowed to evaporate spontaneously, it takes fire when the evaporation is complete. Red or Amorphous Phosphorus is a reddish-brown amorphous powder, of sp. gr. 2.14, insoluble in carbon disulphide; does not alter in the air, and does not show the phosphorescence in the dark. While ordinary phosphorus is very poisonous, even to workmen handling it, this variety is entirely harmless. When heated to 260°C. (500°F.), it does not melt, but gradually sub- limes. The vapor is converted into the ordinary form, which takes fire in presence of air. The red phosphorus is prepared by heating the ordinary va- riety for about thirty-six hours, to a temperature of from 250°C. (482°F.) to 300°C. (572°F.) in an atmosphere of hydrogen, carbon dioxide, or in an exhausted iron vessel. The mass is then washed with carbon disulphide, to remove any of the ordinary variety remaining. Other varieties of phosphorus have been formed. The me- tallic form by heating .the red variety, in a sealed tube, to 530° C. (986° F.) when black, metallic-looking, microscopic needles sublime into the cooler portions of the tube. The sp. gr. of this variety is 2.34, and it is less active than the red variety. White Phosphorus is a form described by Remsen and Keiser as a snow-white, plastic mass, easily oxidized, formed by carefully distilling phosphorus in an atmosphere of hydrogen, and passing the vapor into a receiver containing ice water. Other forms of white phosphorus and black phosphorus have been described, but little is known of them. Chemical Properties.—The most characteristic property of phosphorus is its ready oxidation. If the ordinary or the white variety be heated to 60°C. (140°F.) in contact with air, it takes fire and burns with a brilliant flame, and evolves a volumi- nous white cloud of phosphoric pentoxide. It may be burned under warm water, by throwing a jet of oxygen upon it. It must be kept under water to prevent its taking fire sponta- neously. When fragments, partly covered with water, are ex- posed to the air, white fumes are seen to arise from them, which contain ozone, hydric peroxide, and possibly ammonium nitrite (NHJMCb). This ozone is the cause of the odor usually detected PHOSPHORUS. 145 when phosphorus is exposed to the air. The red variety does not oxidize in the air, and may be handled with impunity. Phos- phorus unites readily with fluorine, chlorine, bromine and iodine, forming, in each case, two compounds of the general formula PR3 and PR5, except in the case of iodine, which forms PJ2 and Pis- An oxychloride of phosphorus (POC1) is also known. It combines with most other elements except carbon, nitrogen and hydrogen. It reduces some metallic salts, as copper and silver, to the metallic state. 222. Tests.—Its phosphorescence in the dark, either as found, or after separating it with carbon disulphide and evapo- ration of the latter liquid. It imparts a green color to the hydrogen flame, when this gas is conducted through a solution containing it before being burned. 223. Physiological Action.—Owing to the ready inflamma- bility of the ordinary variety, deep burns are liable to occur from careless handling, which are more serious and difficult to heal than burns from other combustibles. When taken internally, phosphorus is a very poisonous substance. Cases of poisoning from “ ratsbane ” or “ rat poison ” containing it, are not infre- quent. The symptoms of acute poisoning are a garlicky odor and taste in the mouth, heat and burning in the stomach, vomiting of a dark-colored matter, which is phosphorescent, when shaken, in the dark. Weak pulse, low temperature, cold extremities, dilated pupils, and a clear mind are usually seen. Death in from 2 to 12 days. Average about 3 to 4 days. These symptoms may make their appearance in an hour after the poison is taken, or after 3 or 4 days. Poisonous dose varies. Gr. A to 4 has been fatal. Antidotes. There is no chemical antidote. Emetics, or the stomach pump are the best early treatment; then, mucilaginous drinks, with lime or magnesia, or oil of turpentine. The old oil ls best; but no other oils should be given, as they dissolve the phosphorus and favor absorption. Recovery is rare. Chronic poisoning of workmen in match factories frequently occurs ; the symptoms are fatigue, pains in stomach and bowels, with diarrhoea, carious teeth, swollen and inflamed gums, and finally necrosis of the jaws, usually the lower. Fatty degenera- tion of the liver, kidneys, heart and other muscles, and de- struction of the red corpuscles, are also noticed. These evils are now remedied by using red phosphorus in making matches, as it is not poisonous. 146 INORGANIC CHEMISTRY. 224. Phosphorus and Hydrogen — Phosphoretted Hydrogen. Phosphine.—There are three hydrides of phos- phorus known, which are all formed together by boiling phosphorus with strong potash or soda lye, or with milk of lime. They appear as a gaseous mixture, which takes fire spontaneously on coming to the air. When the beak of the retort in which it is prepared dips under water, a precaution always to be taken, each bubble ignites on coming to the surface, producing beauti- ful white rings of P205. This inflammable gas, composed mostly of PH3, is found, on examination, to contain also a liquid com- pound, (P2H4), which is highly inflammable on exposure to air, while the gas (PH3) is not. This yellow volatile liquid, on standing in sunlight, deposits a yellow solid (P4H2). Phosphine (PH3) is colorless, sparingly soluble in water, and has a strong alliaceous odor. The impure gas is formed during the putrefactive decomposition of organic substances containing phosphorus, especially under water, and takes fire spontaneously on rising to the surface, pro- ducing the ignis fatuus or “Will o’ the wisp” sometimes seen in marshy places. The gas is very poisonous, even in small quanti- ties. The blood after deaths caused by it, is found to be dark colored, with a violet tinge, and has lost the power of absorbing oxygen. It poisons, therefore, by its reducing action on the blood. Its density is 17, and its sp. gr. 1.134. Phosphine resembles the corresponding compound of nitrogen, (NH3),in some respects. It unites directly with HBr and HI, to form phosphonium bromide, (PH4Br), and iodide, (PHJ), corresponding with the ammonium compounds, NH4Br and NH4I. 225. Phosphorus and the Halogens.—Phosphorus forms three compounds with chlorine. Phosphorus trichloride, PC13, is a colorless fuming liquid, boiling at 70°C. (165.2°F.) sp. gr. 1.61, and prepared by direct union of the elements. It is much used as a reagent in organic chemistry. Phosphorus Pentachloride, (PC1)5, is a yellowish-white, crystalline solid, fuming in the air, and subliming without fusion when heated. Prepared by treating PC13 with excess of chlorine, and used as a reagent in organic chemistry. Phosphorus Oxychloride, (POCl3), is formed by the action of a limited quantity of water on the pentachloride. It is a colorless liquid with a pungent odor, and a sp. gr. of 1.7. Boils at 110°C. (230°F.) Phosphorus unites directly with bro- mine, giving a tribromide and pentabromide, and with iodine, giving two crystalline solid compounds, PI3 and P2I4, and with PHOSPHORUS. 147 fluorine to form PF3 and PF5. These latter compounds, as well as those of phosphorus with sulphur, of which there are six known, are of no interest to the medical student. 226. Phosphorus and Oxygen.—The following oxides and acids are known :— Hypophosphorous Acid H-O-P-H \p p2o3 = o=P-o-P=o Phosphorus Oxide N Li Phosphorous Acid j f H—0— \H—0—P~0 [ H—0— Common Phos- phoric Acid.. p2o5 = gEP-o-PEg Phosphoric Oxide Metaphosphoric Acid. H—0—P—q Pyrophosphoric Acid ( H—0\p~ O JH—0—r\0 1H—0\p— Q lH—0/r~U The sodium salt of two other unimportant acids, the hexa- basic and dodecabasic acids, are also known. Phosphorous Oxide, or Phosphorus Trioxide, a white powder formed by the slow oxidation of phosphorus in dry air, is unimportant in medical chemistry. It forms no corresponding acid. 227. Phosphoric Oxide—Phosphorus Pentoxide (P205N), is formed by the rapid burning of phosphorus in oxygen or air, and rises as a voluminous white cloud. It has a powerful affinity for water, producing a hissing noise when dropped into it, and forming a solution of metaphosphoric acid (HPOs). 228. Common Phosphoric Acid.—This is the most im- portant of these acids. Readily prepared by boiling phosphorus diluted nitric acid, and evaporating the solution to a syrupy consistency; or, by decomposing phosphates with sulphuric acid. By spontaneous evaporation over sulphuric acid under a bell jar, bard, transparent, deliquescent, prismatic crystals are obtained. Acidum Phosphoricum (U. S. P.) is a colorless, non-fuming, strongly acid liquid, of sp. gr. 1.347. It should be free from arsenic, which is often present in the commercial acid. Acidum Phosphoricum Dilutum (U. S. P.) is prepared by adding four parts of distilled water to one part of the strong acid, has a sp. gr. of 1.057 and contains 10 per cent, of H:,P04. This acid forms a series of well known salts called phosphates, of which the sodium, ammonium and calcium salts are the most 148 important. The acid being tribasic, it is capable of forming acid, double and triple phosphates, of which the following are examples:— INORGANIC CHEMISTRY. ACID SALTS Di-hydric-sodium Phosphate H2NaP04. Hydro-calcium Phosphate HCaP04. NORMAL SALTS. Potassium Phosphate K3P04. Calcium Phosphate Ca3(P04)2. DOUBLE SALTS. Ammonio-magnesium Phosphate NET4MgP04. Potassio-barium-Phosphate KBaP04. 229. Pyrophosphoric and Metaphosphoric Acids, (H4P207 and HP03).—When ordinary phosphoric acid is heated to a temperature of about 213° C. (415°F.), two molecules lose one molecule of water, and then unite to form a doubly condensed molecule, which is called pyrophosphoric acid. 2H3P04 = H4P207 + H20. If this new acid is heated to a temperature approaching red- ness, the so-called glacial or metaphosphoric acid is formed as a white, glassy, transparent, odorless solid, having a sour taste, and the formula HP03. H4P207 = 2HP03 + H20. This acid corresponds in composition to nitric acid (HNOs). It is usually prepared by heating ammonium phosphate to a red heat. It is deliquescent in the air, and very soluble in water. It has been used as a delicate test for albumin, and has the ad- vantage of being easily handled in the solid state. Meta- and Pyrophosphoric Acids and their salts, when taken internally, are said to have a decided inhibitory action upon the motor ganglia of the heart, and may even cause its cessa- tion and death. Pyrophosphoric has a more decided action than the meta- acid. 230. Hypophosphorous Acid (H3P02).—When ordinary phosphorus is boiled with a solution of sodium, potassium, barium, or calcium hydrate, phosphorus hydride escapes, and there is formed in solution a hypophosphite of the metal present. From the barium salt the acid may be prepared by treatment with enough dilute sulphuric acid to precipitate the barium as sulphate. The filtered solution is then to be concentrated under the air pump, as heat decomposes it. The acid, thus prepared, is a colorless, syrupy, strongly acid liquid ; it is unstable in the air, gradually changing into phosphorous and phosphoric acid. The acid is of little importance, but several of its salts are used in medicine. ARSENIC. 149 They are generally administered in the form of syrup. They have a strong reducing action on many metallic salts, and this should be remembered in prescribing them. Mercuric chloride is re- duced to metallic mercury by the alkaline hypophosphites, and ferric to ferrous salts. _ Hypophosphorous, as well as phosphorous acid, is peculiar in its compo- sition. While there are three atoms of hydrogen in the molecules of both acids, but one in the first and two in the second are basic; i-e., that can be replaced by a basic radical or metallic atom. In these two acids the phos- phorus is pentad, as in phosphoric acid; and in the former the two non- basie hydrogen atoms are believed to be united directly to the phosphorus, while the basic hydrogen atom is linked to it by an oxygen atom, thus— -0-H. 0 P-H _1—H In phosphorous acid we have likewise two hydroxyl groups and one non- basic hydrogen atom, thus— 0—H 0 P—0—H. H These acids illustrate the definition of an acid, given in Part I) viz., that in all acids, except the binary acids, basic hydrogen niust be tied to the kernel element by a linking third atom, usu- ally oxygen or sulphur; and any hydrogen not so united is not basic. 231.—Phosphorous Acid (H:,P03).—Best obtained by the action of water on the trichloride. PC13 + 3H20 = PO3H3 + 3HC1. The HC1 is evaporated, and the remaining solution is concen- trated over sulphuric acid. It is a colorless, syrupy, highly acid and unstable liquid, and under the air-pump may be made to crystallize. It is easily decomposed by heat. It acts as a strong agent by taking up oxygen, and forming phosphoric acid. It forms a series of unimportant salts, called phosphites. ARSENIC 232. Occurrence.—Arsenic occurs native and in the form °t arsenides, the sulphides, orpiment and realgar, and as arsenical Pyrites or mispickel. Besides occurring in these minerals in con- siderable quantities, it is contained in small quantities in a great number of other minerals and even organic substances. The sulphides, and even the element was known to the ancients. As = 75. 150 INORGANIC CHEMISTRY. 233. Preparation.—Usually obtained in the form of the oxide by calcining mispickel, and condensing the white vola- tilized AsjjOi,; this oxide is then strongly heated with charcoal to obtain the element, which distills over. Although this is the method most used, it may be obtained from other minerals con- taining it. 234. Properties.—A brittle, steel-gray, crystalline solid, possessing a metallic lustre, and a sp. gr. of 5.75. It also exists as an amorphous, lustreless, black mass, easily pulverized, and having a sp. gr. of 4,71. When heated out of contact with air, under ordinary pressures, it sublimes at 180°C. (356°F.) without previous fusion ; but under strong pressure it fuses. Its vapor has a yellow color and a density of 150; its molecular weight is, therefore, 300, and its molecular formula As*. In dry air it is permanent; but when heated, it burns with a bluish flame, emit- ting the garlic odor, and white fumes of arsenious trioxide (As203). It combines directly with many of the elements, both metallic and non-metallic, as chlorine, bromine, iodine, copper, iron, etc., yielding arsenides—the metallic arsenides resembling alloys. It combines readily with nascent hydrogen, which takes it from any of its compounds. Nitric and sulphuric acids are decomposed by it, without forming salts. It is oxidized by boiling solutions of caustic potash, while a portion of it is given off as hydride. Arsenic is used in pyrotechny, in the manufacture of fly poison (under the name of cobalt), in shot, and in certain pig- ments. 235. Arsenic and Hydrogen.—Two arsenides of hydrogen are known, AsH3, a gas, and As2H, a solid. Hydrogen Arsenide, Arseniuretted Hydrogen, or Arsine, AsH3—is of great practical interest to the toxicologist, as it enters into some of the most delicate tests for the detection of the element. It may be prepared by a number of reactions, the most common of which are the following:— 1st. By decomposing the metallic arsenides with hydrochloric acid. 2d. By the action of hot caustic potash solutions, with metallic zinc* upon reducible arsenical compounds. 3d. By the action of nascent hydrogen upon arsenical com- pounds, similar to the last mentioned. 4th. By the reducing action of moist organic matter upon compounds of arsenic. ARSENIC. 151 It is a colorless gas, with a strong garlic odor, combustible in air, burning with a bluish-white flame, and emiting white fumes °f As203 ; a cold surface pressed down upon this flame receives a black stain of arsenic. When passed through a tube heated to a dull-red heat, it is decomposed into hydrogen and arsenic, which last deposits in the cooler part of the tube as a metallic mirror. (See Marsh’s Test.) The gas is readily decomposed by oxidizing agents and the alkaline hydrates. It is exceedingly poisonous. The solid Arsenide of Hydrogen is of little interest. 236. Arsenic and the Halogen Elements.—Arsenic forms one compound with each of this group of elements, with the general formula AsR3, in which R stands for a halogen atom. The tri-fluoride and the tri-chloride are liquids, the first boiling at 63°C. (145.4°F.), and the second at 134°C. (273°F.). They are formed when a fluoride or chloride is heated with the trioxide and sulphuric acid. The tri-iodide and tri-bromide of arsenic are obtained by direct union of the elements. They are both solids. The tri-iodide is used in medicine. Both these compounds are decomposed by contact with a small quantity of water; the iodide, however, dissolves in a large quantity of water. It enters into the com- position of Donovan’s solution, as Liquor arsenii et hydrar- Syri iodidi (U. S. P.), which is composed of one part each of mercuric iodide and arsenic tri-iodide dissolved in 100 parts of Water. 237. Arsenic and Sulphur.—There are at least three well known compounds of arsenic and sulphur, As2S3, As2S5, AsSj. . Arsenic Tri-sulphide (As2S3) occurs native, as orpiment, ln the form of gold-yellow crystalline masses. It may be pre- pared by precipitating arsenious acid or its salts, with hydric sulphide, or by heating sulphur and arsenious oxide (As203)# It 18 lemon-yellow in color, soluble in ammonium hydrate and the alkaline hydrates, and in yellow ammonium sulphide, but in- soluble in water and acids. Arsenic Pentasulphide (As2S5) is also a bright yellow powder of no special interest. Arsenic Disulphide (AsS2) occurs native as realgar in the iorm of ruby red crystalline masses of sp. gr. 3.5. Realgar and orpiment are used as pigments. 152 INORGANIC CHEMISTRY. 238. Oxides and Acids of Arsenic.—Arsenic forms two oxides, with corresponding acids:— As203 H3As03 Arsenious Oxide, or Anhydride. Arsenious Acid As205 H3As04 Arsenic Oxide, or Anhydride. Arsenic Acid. Arsenious Oxide (As203) is the most important of the com- pounds of arsenic. It occurs in nature as arsenic “ bloom.” It is obtained artificially as a side product in roasting ores of other metals containing arsenic, when it volatilizes, and is condensed in large chambers as a white powder. It is purified by resubli- mation in iron retorts, and is obtained in the form of a white powder or glassy-looking solid, of a sp. gr. of 3.69. 239. Properties.—As ordinarily met with it (white arsenic) is a white, somewhat gritty powder, which, under the microscope, is seen to be made up of more or less regular octahedral crystals. When the vapor is rapidly cooled, the crystals take the form of rhombic prisms, and it is, therefore, dimorphous. When heated, it sublimes without fusing, at about 218°C. (424°F.) When heated in sealed tubes, it melts into a vitreous mass. The density of the vapor is 198, corresponding to the formula As406, which is probably the formula of the vitreous variety, while that of the octahedral variety is As203. It is soluble, with difficulty, in water, forming a sweetish, metallic, and nauseous-tasting, poi- sonous solution of arsenious acid (q. v.) It is also soluble, with decomposition, in hydrochloric acid and alkaline solutions, play- ing the basic role in the former, and the acid role in the latter. Nascent hydrogen reduces the oxide, and converts the arsenic into arsine (AsH3), while oxidizing agents convert it into arsenic acid. Antidote.—Freshly prepared ferric or magnesium hydrate, or a solution of dialyzed iron. 240. Arsenious Acid, (H3As03), is formed by dissolving As203 in water. A solution of the acid in dilute hydrochloric acid* is officinal under the name of liquor acidi arseniosi (U. S. P.), containing 1 per cent, of As203. It forms a series of salts called arsenites. Potassium arsenite is officinal as Fowler’s solution, or Liq. Potass. Arsenitis. Scheele’s green is an arsenite of copper, used as a pigment. Paris green is a mixture of acetate and arsenite of copper. . 241. Arsenic Oxide, (As205), is a white, amorphous, deli- quescent solid, dissolving in water to produce arsenic acid. -A.S205 -f- 3H20 — 2H3 As04. ARSKNIC. 153 Arsenic acid is usually prepared by warming arsenious acid with nitric acid, when the As203 is oxidized at the expense of the nitric acid. On evaporating, the solution yields needle-shaped crystals of H3As03. The aqueous solution is strongly acid. On heating the crystals of arsenic acid, both the pyro-arsenic and meta-arsenic acids are produced, corresponding to the similar acids of phosphorus. But one salt of this acid is officinal, the Liquor Sodae Arseniatis. 242. Arsenic Poisoning—Toxicology.—From the earliest history of arsenic, it has been used as a poison for criminal purposes. While every physician should not undertake the analysis in cases of suspected poisoning by this agent, a knowledge of the outlines of the chemist’s methods of analysis, etc., will teach the physician to prepare the way for the analyst. Moreover, a few preliminary tests by the physician may frequently save much unnecessary litigation and expense in some suspected cases. Other reasons might be given why every physician should have some knowledge of toxicological science, that care may be taken to punish the guilty and protect the innocent. The attending physician is responsible for the connection of the links of evi- dence. All compounds of arsenic are poisonous, and the poison usually enters the system by the mouth, although it has been absorbed by the skin, mucous membrane, or abraded surfaces, ln sufficient quantities to produce poisonous results, especially chronic poisoning. Colored wall paper, colored toys, confectionery, and certain aniline dyes used in fabrics, may give rise to accidental poisoning. 243. The Physician’s duty in cases of Poisoning may be briefly stated as follows: In case foul play is suspected, do not fail to make careful notes, at the time, as to dates, symptoms and circumstances, or facts leading to such suspicion. The physician should collect and preserve the urine, faeces, vomit, and the suspected vehicle of the poison, and place them under seal, or lock and key. He should test some one or all of these, to satisfy himself as to the truth or falsity of his suspicion. As little publicity as possible' should be given to matters of fact or opinion at the time. Be not too ready to express your opinion upon the origin of the poison in cases of this kind, lest vou jeopardize the reputation of your patient or others. VV hether a fatal termination is expected or not, it is wise to take these precautions. In case of fatal termination, notify the prosecuting officer or 154 INORGANIC CHEMISTRY. coroner of your suspicion, and request an autopsy immediately; but remember that you are not released from your responsibility in the case by so doing, nor are you at liberty to tell all you know, until you are summoned to do so on the witness stand. Before you attend the autopsy, read carefully, and refresh your memory upon the directions for making post-mortem examinations, and on post-mortem appearances in cases of poisoning, whether you are to make the examination yourself or not. If possible, see that the chemist who is to make the analysis is present at the autopsy. (See Woodman and Tidy, “ Forensic Medicine.”) The entire intestinal canal, at least one-half of the liver, the spleen, one kidney, the brain, and any urine remaining in the bladder, should be saved ; the brain and entire intestinal canal, ligatured at both ends of the stomach and left unopened, are to be preserved in separate jars, while the other organs may be placed in another jar. These jars must be new and clean, and closed with new corks or glass—not with metal caps. They are then to be closed with a seal, with some peculiar stamp upon it, so that they cannot be opened without detection. They must not be entrusted to a servant or any irresponsible person, but turned over as soon as possible to the chemist, or to the prosecuting officer or coroner. Notes, to be admitted in the witness box, must be the original; not a copy of those taken at the time to which they refer, or im- mediately after. 244. Symptoms of Arsenical Poisoning.—The symptoms are those of an intense irritant. There is usually marked “ fire- burning” pain in the epigastrium, increased by pressure. Vio- lent vomiting, tenesmus, burning pains at the anus, and painful cramps in the legs, are usually present. Intense thirst, dry hot skin, severe headache, small rapid pulse, anxious pinched coun- tenance, the eyes suffused and smarting, tongue dry and furred, photophobia, great restlessness, nervous twitehings, with a per- fectly clear mind, are symptoms usually to be expected. The urine is diminished, with frequent and painful micturition. These symptoms may end in convulsions, tetanus, collapse, or coma and death. Minimum fatal dose, from 1.5 to 2.5 grains. Chronic arsenical poisoning is usually attended by conjunctival inflammation, irritation of the skin with a vesicular, or nettle-rash eruption, similar to that of scarlet fever. Irritation of the stomach and bowels, exfoliation of the cuticle of skin and tongue, and falling of the hair, have been noticed. Local paralyses, preceded by numbness, or tingling of the toes and fingers, and marked nervous disorders, are of common occurrence. ARSENIC. 155 245. Treatment.—Remove any unabsorbed poison from the stomach by emetics or the stomach pump. The best antidote is freshly precipitated ferric hydrate, pre- pared by adding aqua ammonise, in slight excess, to a solution of ferric sulphate or ferric chloride. The solution of dialyzed iron, now found in the shops, may be used instead of the above, and may be given in teaspoonful doses at short intervals. This forms an insoluble compound with the arsenious acid, and thus pre- vents further absorption. The symptoms caused by the absorbed poison are to be treated ns they arise. 246. Tests.—There have been devised a large number of tests for the detection and identification of arsenic. Some of these are easy of application, while others will be used only by the chemist. AVe can only give the outline of these tests, and leave the student to consult special works for minutiae. The analysis, after death, in cases of suspected poisoning, should not be undertaken by the physician, nor even by a chemist, unless be has a well equipped laboratory in which he can conduct the analysis, from beginning to end, alone, and without interruption. Inuring the life of the patient, the physician should be able to test the urine, faeces, or suspected articles of diet, medicines, etc., for the presence or absence of arsenic. For this purpose he may use Reinsch’s or Marsh’s test, but it must be understood that neither of these tests alone, when performed as about to be de- scribed, is to be relied upon as positively certain. Reinsch’s test may be conducted as follows:— To a portion of the urine or other suspected liquid add about one-sixth its volume of pure hydrochloric acid and some strips °f pure copper foil, and boil the solution. If arsenic be present, a steel-gray or bluish deposit will be formed on the surface of fhe copper. This deposit is not positive proof, however, as anti- mony, bismuth and mercury may give similar deposits; it is, therefore, necessary to apply tests to this deposit, in order to determine its identity. For this purpose the copper is removed, tvashed in water, dried between folds of filter paper, and placed lu a clean, dry, wide test tube, and heated to a dull red heat, taking care to heat only that portion of the tube where the copper is. The tube may then be broken and the inner side of the fragments examined with a microscope, for octahedral crystals of arsenious oxide. The copper and the acid used must be shown to give no stain on prolonged boiling with distilled water. This blank experiment must always be performed. 156 INORGANIC CHEMISTRY. Marsh’s test may be conducted as follows:—Although the indications afforded by it are not conclusive in the pres- ence of organic matters, it should always be used to confirm Reinsch’s test. Into a flask holding about 150 c.c. (f ■§ v), introduce some pieces of zinc, free from arsenic and antimony ; •then pour over these some water acidulated with sulphuric acid; close the flask with a cork containing a funnel tube, and a delivery tube drawn to a fine point and containing a pledget of cotton in the end at th£ cork, arranged as in Fig. 35. After allowing the generation of hydrogen to go on for a considerable time, to expel the air from the upper part of the flask, say half an hour, light the gas at the open end of the de- livery tube, and press a cold porcelain surface down upon the flame. If the materials used are free from arsenic and antimony, there will be no black stain produced on the porcelain. Fig. 35. Having determined that the apparatus and materials are free from impurities, put out the flame and pour the suspected fluid through the funnel tube, so as to admit little or no air with it into the flask. Now ignite the gas again, and test the flame again with the cold porcelain surface. A brilliant black or brown stain, soluble in a solution of sodium hypochlorite, is proba- bly arsenic. Moisten one of these spots with nitric acid, when it should disappear; evaporate the acid over a lamp, moisten the spot with water, and hold the dish over a vessel containing sul- phuretted hydrogen, prepared by the action of sulphuric or hydrochloric acid upon sodium or potassium sulphide. If the stain was due to arsenic the spot will turn lemon-yellow. The anti- mony mirror is insoluble in sodium hypochlorite (Labarraque’s ARSENIC. 157 solution) and after treatment as above gives an orange stain. Now soften the glass, bend delivery tube downward and let it dip into a solution of AgNOs; after an hour pour some NH4OH upon the surface of AgN03 solution. Yellow precipitate at line of separation = arsenic. If the substance to be tested is a solid, a small portion of it may be thrown upon a glowing charcoal, when arsenic, if present, will give an odor resembling garlic. These tests will he sufficient to enable the physician to decide upon the Presence of arsenic during the life of the patient, and guide him his treatment and behavior. 247. Toxicological Analysis.—The chemist who undertakes the analysis in cases of supposed poisoning has no easy task. He must not confine his tests to any one poison. Poisons are gener- ally divided into two groups, inorganic and organic. The limits of this work will not allow us to describe the details °f procedure for the chemist, who will consult special works on toxicology. In searching for mineral poisons, the organic matters must first he destroyed or separated by dialysis. For the‘latter process see Part I, Art. 72. For the destruction of organic matter, two methods may be used. The solid matter—the stomach, and other organs—are to he cut in fine pieces and placed in a new porcelain dish, mixed Wlth hydrochloric acid, and heated over a water-bath. Small quantities of pure potassium chlorate are put in from time to time uud stirred, until the organic matter is destroyed. Or, sulphuric and nitric acids are used to thoroughly char the organic matter, and the whole diluted with water and filtered. The metals, except mad and barium, pass into the filtrate, and can be detected by either of the methods given above or by other methods. These solutions maybe treated with hydrosulphuric acid gas from 24 to 48 hours, when copper, lead, bismuth and mercury give black or brown precipitates; cadmium, sometimes tin, arsenic give a yellow, and antimony an orange precipitate. In searching for arsenic, the yellow precipitate obtained, is separated from the liquid by filtra- tion. A portion of this is to be preserved in a sealed glass tube. The remainder is oxidized with nitric acid, fused with sodium carbonate and nitrate, and the sodium arseniate thus formed may he made to yield silver and copper arseniates; the former a reddish-brown, aud the latter a green precipitate. Other portions are converted ]uto the octahedral crystals of trioxide, the metallic state, etc., the object being to present the poison in court in as many different states as possible, so as to avoid the possibility of doubt in the 158 INORGANIC CHEMISTRY. minds of the jury. If the yellow sulphide, soluble in ammonia, the black metal (so called), the octahedral crystals, the mirrors with the above mentioned properties, the coated copper obtained by Reinsch’s test, the black deposit from silver nitrate in Marsh’s test, with arseniate in the filtrate, the arsenite and arseniates of silver, and arsenite of copper, etc., etc., are obtained, with proper precautions, there is no room for doubt that the substance is really arsenic. For further directions on this subject, the student is referred to Taylor on poisons, or Woodman and Tidy on Forensic Medi- cine and Toxicology, or some other similar work. ANTIMONY. Stibium, Sb = 122, Sp gr. 6.71. MeltiDg point 450°C. (842°F.l 248. Occurrence and Preparation.—Antimony occurs native; but the principal source is the trisulphide, Sb2S3, called stibnite. It ocpurs in a number of other ores as sulphide, or oxide. The element is easily obtained by roasting the sulphide, and then fusing the oxide thus obtained, with charcoal. 249. Properties.—Antimony is a bluish-white, brittle, crys- talline solid, isomorphous with arsenic and red phosphorus, and resembling zinc in color and lustre. Tarnishes with difficulty, but takes fire at a red heat. It unites readily with chlorine, forming two chlorides, SbCl3 and SbCl5, both of which are de- composed by excess of water. In physical properties it resembles metals, and forms alloys. In chemical properties it plays both the positive and negative roles with facility. It is used as a con- stituent of type metal, Babbitt’s anti-friction metal, Britannia, etc., to give hardness, and to cause them to expand and com- pletely fill the moulds in cooling. 250. Hydrogen Antimonide, Stibine, Antimoniuretted hydrogen (SbH3).—A colorless, odorless gas, formed in the same conditions as the corresponding compound of arsenic ; i. e., by nascent hydrogen on reducible antimony compounds. It differs from that compound in being much less poisonous, and giving a different reaction with solutions of silver nitrate, as shown in the following reactions :— 6 AgN03 -f- AsH3 -)- 3H20 — 6 HN03 -f~ H3As03 -I- 3Ag2 3 AgNOg + SbHg — 3HN03 + SbAg3 Silver Antiinonide. Metallic Silver. By carefully floating a solution of ammonium hydrate over the ANTIMONY. 159 hrst solution, after passing the gas through it for some time, a yellow precipitate of arsenite of silver will be formed at the line °f separation of the two liquids, while, in the case of antimony, no such precipitate will be formed. This gas is formed in Marsh’s apparatus, and it is likely to be confounded with arsenic unless very great pains be taken to avoid it. The mirrors obtained on the porcelain or in the delivery tube, require a higher temperature to volatilize them in the case of antimony; they are difficultly soluble in hypochlorite solution, are sooty and less brilliant in appearance, there is no garlic odor, and by oxidation they do not form crystals. 251. Chlorides, Bromides and Iodides.—Two chlorides and two oxychlorides exist. Antimony Chloride, or A. Trichloride—A. Protochlo- ride—Butter of Antimony (SbCl:!), may be obtained by dissolving the trisulphide in hydrochloric acid. At low tempera- tures it is a crystalline solid, and melts at 73.2° C. (164° F.) to a yellow, oily liquid. A solution of sp. gr. 1.47 is sometimes used as an escharotic. On the addition of considerable water, this chloride is decomposed into the oxychloride (SbOCl), formerly called powder of algaroth. SbCl3 is poisonous, acting both locally and as a true poison. Antimony Pentachloride (SbCl5) is a fuming, colorless liquid, of little interest to the medical student. The iodides, bromides and fluorides, are similar to the trichloride in com- position. The iodide has been used in medicine. 252. Sulphides of Antimony.—Two sulphides are known and several oxysulphides. Antimony Trisulphide—Sul- Phuret of Antimony—Black Antimony—Antimonii Sul- phidum (U. S. P.), Sb2S:j, occurs native as a steel-gray, crystal- line solid. Artificially, it may be prepared by precipitating a soluble antimony salt with hydrogen sulphide as an orange- colored powder. When the native ore is roasted in air it is partially decomposed, and fuses into a vitreous, somewhat trans- parent mass, known as glass of antimony, or crocus. Antimonii Sulphuretum (U. S. P.) is a reddish-brown powder prepared by dissolving the native sulphide in a solution of sodium hydrate, and re-precipitating the hot solution with sul- phuric acid. It contains a little antimonious oxide (Sb203), and used mostly in pill form. Dose gr. ij to xx. Plummer’s Pills, Pil. antimonii comp, contain this sulphide with calomel. Dy treating a hot solution of the trisulphide with sodium hypo- sulphite, a fine red precipitate of oxysulphide is obtained, wliich 160 INORGANIC CHEMISTRY. is used as a pigment, under the name of antimony vermilion. Kermes’ mineral is another oxysulphide. Antimonium Sulphide (Sb2S5) is best obtained by decom- posing sulphantimoniates with a dilute acid. It is an orange-red or brown powder, readily soluble in alkalies and alkaline sulphides, forming antimoniates with the general formula M3'Sb04, in which M stands for a metallic atom. Sulphantimoniates of silver, lead, and iron, occur as minerals. 253. Oxides and Acids of Antimony.—Three oxides are known. Antimony trioxide Sb203, antimonious acid HSb02. “ pentoxide... Sb205. “ tetroxide.... Sb204, or SbO.Sb03. Antimony Trioxide (Sb203) is obtained by roasting the metal in air, or by treating it with HN03 and evaporating excess of acid. It is dimorphous and crystallizes in the same forms as As203, and is therefore isomorphous with it. It is a white powder capable of being sublimed. Antimonious Acid or Hydrate (HSb02) is obtained by adding a solution of sodium carbonate to a solution of SbCl3, as a white precipitate. 2 SbCl3 + 3 Na2C03 + H20 = 2 Sb02H + 6 NaCl + 3 C02. By boiling, this hydrate is changed into the trioxide. It re- acts with both acids and alkalies to form salts. Thus, we have NaSb02, ShO(Js03) and Sb(N03)3. We also have antimony sulphate (Sb2(S04)3—and antimonyl sulphate (Sb0)2(S04) —the former by dissolving the oxide in strong, and the latter in dilute sulphuric acid. Both are decomposed by excess of water. Antimonic Acid (HSb03)—is obtained, by treating antimony with warm concentrated HN03, as a white powder, insoluble in water and nitric acid. Pyro-antimonic Acid (H4Sb207)—is also known, and may he obtained by treating its salts with hydrochloric acid. By gently heating either of the above acids, antimony pen- toxide is obtained as a yellow, amorphous mass, and by a stronger heat, with free access of air, it is converted into the tetroxide— Sb204—which is usually regarded as an antimoniate of antimonyl (SbO Sb03). It is a white, non-volatile powder, becoming yellow when heated. 254. Potassium Antimonyl Tartrate.—Tartar Emetic —Antimonii et Potassii Tartras (KSb0C4H406.H20) is one of the most commonly employed compounds of antimony. 161 Prepared by boiling 3 parts of Sb20:i with 4 parts of cream of tartar (KH C4H406) in water, for an hour, filtering, evaporating the filtrate and allowing it to crystallize out. It occurs in small, transparent, rhombic crystals, which effloresce in air, and have a sweetish, afterward disagreeable, metallic taste and acid reaction. Soluble in 17 parts of water at 15°C. (59°F.), and 3 parts boiling Water; insoluble in alcohol. Its solutions are incompatible with alcohol, hydrochloric acid, and alkaline carbonates. Tartaric acid prevents the precipitates caused by the above reagents. On being heated to redness it chars. It is used in medicine, and enters into the composition of Syr. scillae compositus, Vinum antimonii and Unguent, anti- rnonii. The dose of tartar emetic is gr. j-ij (.065-.125 grms.), as an emetic; as an expectorant, gr. tV to gr. \ (.004-.016 grms.); of the wine, 10 to 30 drops. 255. Physiological Action.—Locally, the soluble com- pounds of antimony act as powerful irritants. Tartar emetic causes a pustular eruption resembling variola, which is accompa- nied with fever and systemic results. Cases of poisoning from antimony used in dyeing clothing have been reported. Inter- nally, tartar emetic is employed as an expectorant, sudorific, sedative, nauseant and emetic, according to the dose used. In full doses it causes vomiting, purging, griping pains, with great depression. In excessive quantity it acts as an irritant poison, and has produced death by syncope, preceded by convulsions and delirium. One and a half grains (.092 grms.) have produced death, but recovery has occurred after very large doses, because °f the rejection of the poison by vomiting. The treatment should consist in promoting free vomiting, or removal of the poison with the stomach pump. The proper an- tidote is tannic acid, which forms an insoluble compound with antimony; it may be administered in the form of infusion of tea, oak bark, nutgalls, etc., which contain it. Stimulants are then to be administered. In suspected cases, examine the urine or viscera by Marsh’s test (Art. 246). Soluble salts of antimony give an orange-colored precipitate with H2S, in acid solutions, which is soluble in yellow ammonium sulphide, and in strong hydrochloric acid (HC1). In Reinsch’s test, a bluish stain is obtained, but the sublimate obtained from it is amorphous, not crystalline. (See Art. 246.) ANTIMONY. 162 INORGANIC CHEMISTRY BISMUTH. Bi = 210. 256. Occurrence and Preparation.—Occurs native and as sulphide—bismuthinite. The element is obtained by roasting the sulphide in air, and reducing the resulting oxide with charcoal. 257. Properties. — Bismuth is a white, metallic-looking solid, with a bronze tint. Sp. gr. 9.9. Brittle, and crystallizes in rhombohedrons; fuses at 267°C. (512.5°F.), volatilizes at a white heat, and if heated in air it burns to Bi203. HN03 and hot H2S04 dissolve it, but HC1 does not. Water precipitates basic salts from the solutions of the neutral salts. It alloys with the metals, and is sometimes described as a metal. 258. Bismuth Chloride (BiCl3) may be obtained by treating the element with chlorine or aqua regia. It is a soft, white, deliquescent, volatile solid. Water added to its solutions pre- cipitates the white oxychloride. BiCl 3 + II20 = BiOCl + 2HC1. This reaction resembles that of SbCl3. BiOCl, as well as the subnitrate, is sold as pearl powder, or pearl white, and used as a cosmetic. They blacken by H2S. The compounds BiBr3 and BiB are similar to BiCl3. Bismuth does not form a hydride (BiH:i), as do the rest of the group. 259. Oxygen Compounds.—Bismuth oxide (Bi203) is a yellow powder, insoluble in water and alkalies; it may be pre- pared by roasting bismuth, or heating the nitrate or carbonate. When chlorine is passed through a solution of potassium hydrate, in which Bi203 is suspended, bismuthic acid (BiO:,H or H4Bi207) is precipitated as a red powder. On gently heating this the pentoxide, or bismuthic oxide (Bi205), is formed. Bismuth hydrate (BiO:!H3) is not known, but a metahydrate (Bi02H) is precipitated when caustic soda or potassa is added to a bismuth solution, or to the nitrate suspended in water. This oxide is the one first precipitated in testing for sugar in Boettger’s test. 260. Bismuth Nitrate (Bi(N03)3) is formed by dissolving bismuth or the basic nitrate in nitric acid and evaporating, when it crystallizes in large transparent tables (Bi(N03)35H20). It is soluble in a little water, but is decomposed by a large amount into a basic or subnitrate. BISMUTH. 163 a—N03 tv—NO 3 -NO3 + 2H20 = K -OH + 2HNOs, or —NO 3 OH TV N03 TV N03 R -N0» + H*° = nl--N°3 + HN03, or "A—oh4 Bi-(N08). + H20 =Bi-°N°3 + 2HN0S. Bismuthi Subnitras. (U. S. P., Hr. P.)—The subnitrate of bismuth is not a definite and fixed compound, but a mixture. It is a white powder, insoluble in water, but soluble in nitric acid. As arsenic and bismuth frequently occur together, the latter is apt to be contaminated by the former. Should unpleasant effects arise from its use, it should be tested with one of the tests described under arsenic (q.v.) It is used internally, and as a dressing for wounds. 261. Bismuth Carbonate — Bismuthi Subcarbonas -ry ° (U. S. P.)—Bismuthi Carbonas (B.P.)— C03, is a light, white, odorless and tasteless powder, insoluble in water, and formed by the action of alkaline carbonates upon solutions of bismuth. Heated, it is changed into Bi203 and carbon dioxide. Bismuth Sulphate (Bi2(S04)3) is formed by dissolving bis- muth in sulphuric acid. It is of no special interest to physicians. 262. Bismuth Citrate (BiC6H507) is a white, amorphous powder, odorless and tasteless, insoluble in water or alcohol, but soluble in ammonium hydrate. Prepared by boiling Bi0N03 in a solution of citric acid, and precipitating the citrate with water. % dissolving the citrate in dilute ammonia water, and cautiously evaporating to a syrup, and spreading on glass, shining, pearly, or translucent scales of Bismuth et Ammonii Citras are ob- tained, soluble in water. A solution of 2 pts. BiON03, and 4 pts. KNaC4HtOB) in a strong solution of sodium hydrate is used as a delicate test for diabetic sugar. It becomes black from reduction of bismuth. . 263. Physiological Action.—The bismuth salts in medi- cinal doses are tonic, antispasmodic, mildly astringent and anti- fermentative. They are used to allay gastro-intestinal irritation and diarrhoea. When administered in considerable quantities they form black stools, from the presence of the sulphide formed oy the ITS of the intestines. In many cases of excessive diarrhoea, with acid fermentation in the stomach and intestines, this black- 164 INORGANIC CHEMISTRY. ening does not occur, and its appearance marks an improvement in the case. Cases of poisoning by large doses of the salts of bismuth are generally, if not always, due to the presence of arsenic in them. 264. Tests.—Water precipitates, in the absence of free min- eral acids in considerable quantities. Hydrogen and ammonium sulphides give a black precipitate, insoluble in water, dilute acids and alkaline sulphides. Potassium,Sodium and Ammonium Hydrates give a white precipitate, insoluble in excess of the reagents. Infusion of nutgalls gives an orange precipitate. Potassium Iodide gives a brown precipitate, soluble in excess of reagent. A piece of paper dipped in a solution of potassium sulphocyanide and dried, forms a yellow spot when a drop of a solution containing bismuth is dropped on it. BORON. 265. Occurrence and Preparation.—An unimportant element, never occurring native, but as borates and boric acid. Borates of calcium, magnesium and sodium (borax) occur native ; the last, the most important, is found in India and California. The element may be prepared in two allotropic states; the first, by fusing its oxide with sodium or potassium, as a greenish-brown powder; the second, by fusing the oxide, chloride, or fluoride with aluminium, as a crystalline transparent solid, varying in color from colorless to a garnet red. Boron combines directly with nitrogen at elevated temperatures. 266. Boric Anhydride and Acids.—B203 is a transparent, glass-like mass, obtained by heating boric acid to redness. It is used in blow7pipe analysis. Boric or Boracic Acid (H3B03)—exists native in lagoons, in the vicinity of volcanoes in Tuscany. By evaporation and crystallization the acid is obtained. Borate of sodium or borax occurs in California and India, and from it the pure acid is prepared by precipitating it with HC1 from a hot solution. The acid separates in white, shining scales; it is soluble in 25 parts of H20 at 14° C. (57.2° F.), and in 3 parts of boiling H20. The solution has a faint acid reaction. Turmeric paper moistened with the solution assumes a reddish-brown color on drying. The acid is soluble in 6 parts of alcohol, and is also soluble in glycerine, to the flame of both of which it imparts a distinct green color; this and the action on turmeric paper are used as tests. B = 11. SILICON. 165 When boiled with glycerine, an ether is formed, known as boroglyceride, which is soluble in water, has a neutral re- action, is tasteless, and is used as a preservative for foods. Its ose, as well as that of boric acid, is attended, in considerable doses, with an increased excretion of urea with irritation of the kidneys, and should be used with some caution. Owing to its antiseptic action, it is used in surgical dressings. When heated, H:;B03 loses one molecule of water at 100° C. (212° F.), and forms metaboric acid (HB02) ; on further heat- ing it forms tetraboric acid (H2B407), and at a higher tem- perature boric anhydride is formed. SILICIUM—SILICON. Si = 28. 267. Occurrence.—In native rocks, either as silicic oxide (Si02), quartz, amethyst, carnelian, etc., or combined with vari- ous metallic oxides as silicates. Clay is principally a silicate of aluminium colored with iron and vegetable matter. This, next to oxygen, is the most abundant of the elements. Neither the element nor its compounds are of much interest to the medical student. The element never occurs native, and may be prepared in three allotropic states: amorphous silicon, graphitic sili- con, and crystallized silicon, somewhat resembling the three states of carbon. 268. Compounds.—Silicic Hydride (SiH4) is obtained as a colorless, spontaneously inflammable gas, by the electrolysis of a solution of common salt, using for the positive electrode an aluminium containing silicon. Silicic chloride (SiCh) is a color- less, volatile liquid possessing an irritating odor. The bromide, SiBr4, and fluoride, SiFl4, are also known. This latter is de- composed by water, forming hydro-fluo-silicic acid, H2F6Si. 269. Silicic Oxide, or Anhydride (Si02), is the only known oxide of this element, and exists in a pure state in quartz crystal. Artificially, it may be prepared by adding hydrochloric acid to a concentrated solution of soluble or water glass, filtering, wasti- ng and heating the residue, to expel the water. Artificially prepared it is a fine, white, tasteless powder, fusible with great difficulty, and not sensibly soluble in water or acids, with the exception of hydrofluoric acid. Its sp. gr. is 2.66. When fused with potassium or sodium carbonates or hydrates, it forms a silicate of these metals, or glass; when these alkalies are in excess, the glass is soluble in water, the degree of solubility increasing with 166 INORGANIC CHEMISTRY. the proportion of alkaline- salt used. This compound is known as soluble or water glass. 270. Silicic Acid and Silicates.—The normal silicic acid has the formula H4S204, and is only known in solution in water. It may be prepared by adding hydrochloric acid to a very dilute solution of an alkaline silicate, but it is unstable. The acid is very prone to liberate a portion of its water and form acids of the condensed types; i. itch, or heavy oils, rich in carbon. It is used principally as a pigment. Animal charcoal or bone black is obtained by the carbonization of animal matter from slaughter houses (blood, bones, etc.), and possesses in a remarkable degree the power of removing the coloring matter or putridity from organic solutions filtered through it. It is used in the refining of sugar to remove the color from the solution of raw sugar. Carbo animalis purificatus is prepared by treating the above with dilute HC1, to remove the calcium phosphate. Charcoal, carbo ligni (U. S. P.), is carbonized wood, retaining, usually, the form and grain of the wood and the ash contained in the same. In pre- paring it, the wood, cut into suitable lengths, is piled up on end into a conical heap, a trough made of boards being laid from the circumference on one side to the centre, to supply air. The w hole heap is then covered, first with straw or leaves, and finally with dirt about six or eight inches in thickness, except a hole at the centre on the top. The fire is lighted and is allowed to burn slowly, until the flame almost ceases to come from the hole at the top, or until the gaseous products have all burned off. This opening at the top, as well as the draught holes, is now covered over and the fire allowed to smoulder for a time, when the heap is torn down and the remaining fire extinguished with water. 168 INORGANIC CHEMISTRY. It is used as a fuel, in the manufacture of gunpowder, and sometimes in the construction of filters, as it possesses, in a feebler degree than animal charcoal, the power of destroying noxious odors, and filtering coloring matters from organic solutions. 1 volume of it absorbs 90 volumes of NIT,, 55 volumes of H2S and 9 volumes of oxygen at 100° C. (212° F.). It is very porous, and burns with little flame. Coke is the porous mass left in the retorts from the destructive distillation of mineral coal in the production of illuminating coal gas. Gas retort carbon is a compact, hard mass found adhering to the inside of the retorts in the above process of manufacturing coal gas. It has a metallic lustre at times, and is a good conductor of electricity, and is used for the negative plate in the construction of many forms of the galvanic battery. Mineral coals (anthracite, bituminous, brown and cannel coals, lignite, peat, or turf, etc.), are the results of a slow decay, under certain conditions, of vegetable matter. The proper conditions for its formation seem to be, enough water to cover the fallen timber or vegetation, and then a covering of clay or mud, to ex- clude the air and apply pressure to the mass. The liquid and volatile portions are gradually lost, leaving the carbon behind. The final product of this change, assisted by subterranean heat, is anthracite coal, which often contains 96 to 98 per cent, of carbon, and almost no volatile products. Petroleum oil is be- lieved to be the expelled liquid portions of the wood, separated from the anthracite coal by heat and pressure. Bituminous coal is a softer, less compact, less decayed variety. It often con- tains the structure of the wood. It burns with a smoky flame, while the anthracite furnishes very little or no flame. Brown coal, lignite, and wood coal, are names of less perfect varie- ties than those before mentioned. Peat, or turf, is a mixture of mud with partially decayed plants and roots, obtained from certain marshy districts. It is used as fuel. Cannel coal is a compact, even-textured coal, without lustre, and takes fire readily, burning with a clear, yellow flame. It has been used as candles—hence the name. 274. Properties.—Carbon is insoluble in all ordinary men- strua, but soluble to a slight extent in molten cast-iron, forming a carbide. It. is fused and volatilized only in the voltaic arc. At ordinary temperatures it is permanent in air and all chemical reagents. "At high temperatures it has a strong affinity for oxygen, and on this account it is used as a reducing agent in smelting the ores, from which it removes the oxygen. Indi- CARBON. 169 rectly, it enters into combination with a great many of the ele- ments. In combination with hydrogen, nitrogen and oxygen, it forms a large share of organic bodies. Most combustible bodies Contain carbon. 275. Coal Gas.—Illuminating gas, as it is often called, is made oijrra large scale by the dry or destructive distillation of bituminous coal. In principle, the manufacture is simple; but m practice, it requires considerable skill to prepare a good illu- minating gas. During the distillation, which is conducted in horizontal, semi-cylindrical, fire-clay or cast-iron retorts set in brickwork, a variety of products are produced besides the gas, such as tar, heavy oils, lighter oils, steam, ammonia from the nitrogen of the coal, etc. There is left in the retort a porous, friable mass, called coke. After the retorts have been used for some weeks, there is to be found lining their inner surfaces a very compact layer of carbon, usually known as gas retort carbon, and used in making the negative plates in some forms of electric batteries, and the poles of electric lights. In many of its properties it resembles graphite. The coal is distilled at a bright red heat, and the volatilized products are conducted into a large, horizontal, iron pipe, half filed with water, into which the pipes from the retorts dip. This is called the hydraulic main. A large part of the coal tar and heavy oils condense in this main. The volatile products are then made to traverse a series of upright tubes, in the form of an inverted U, called condensers. The lower end of one limb of each condenser dips under water, so as to cool the gas, and to dissolve the ammonia in it. After travelling a number of these condensers, where the remainder of the tar, steam and ammonia liquor are condensed, the gas passes to the purifiers, which are composed of a series of large boxes, in which are several perfo- rated shelves, or trays, holding fresh slaked lime, or a mixture of sawdust and iron oxide. The gas is passed slowly through these purifiers, so as to expose it to the action of the lime or iron oxide, to remove H2S, C02 and other volatile acids, if present. Ju some plants there is an additional process of washing the gas by passing it through wTeak sulphuric acid, to remove the small quantity of ammonia still remaining. The tar and ammonia bquor are sold as by-products, and the latter furnishes a very considerable portion of the ammonium compounds of the market. After passing through the purifiers, the gas is conducted in underground pipes to the gasometer, to be stored until needed. Ihe gasometer is a very large, tub-shaped vessel, made of 170 INORGANIC CHEMISTRY. boiler-iron floated bottom upward upon water, and balanced by weights attached to chains passing over pulleys at the top of iron pillars, which are erected around the gasometer for that purpose. As the gas is forced into the gasometer, the latter rises out of the water, and sinks again as the gas is used. Various other processes for the manufacture of gas have been used with varying success; such as, the distillation of the heavy petroleum oils, either alone, with coal, or with admixture of the vapors with air or steam. Gasoline, or air gas, is air saturated with the vapors of the very volatile oils from petroleum. Water Gas is very largely used in all large cities, owing to cheapness of manufacture. It is made by the action of steam upon coal heated to a red or white heat. The gas thus produced, is, in some works, mixed with vapor from naphtha, and then again strongly heated in retorts, and finally purified, as in ordinary coal gas. Composition.—The composition of coal gas varies somewhat with the composition of the coal used, and the temperature of the retorts during the distillation. The following figures represent the composition of coal gas and water gas supplied to Brooklyn in 1883 :— Coal Gas. Water Gas. Carbon dioxide 0.0 0.3 Carbon monoxide 7.9 28.25 Hydrogen 50.2 30.3 Illuminants (C2H4, C2H2, etc.) 4.3 12.85 Marsh gas (CH4) 29.8 21.45 Nitrogen 7.8 6.85 100.00 100.00 (Remsen). 276. Carbon and Oxygen.—There are four oxides of carbon known, having the formula} C803, C403, CO and C02. The first of these compounds is a light brown powder, formed by heating the suboxide (C403). Carbon Suboxide is an amorphous extractive matter formed by the action of an electric current upon carbon oxide. Carbon Monoxide (CO-) is a colorless, tasteless, almost odorless, combustible, poisonous gas. It is always produced when carbon or bodies containing it are burned with an insufficient supply of oxygen or air, or by conduct- ing carbon dioxide over or through red hot coals, C02 + C = 2CO. It may be prepared by warming oxalic acid with sulphuric acid. H2C204 + H2S04 = H4S05 (or II20, H2S04) + C02 + CO. CARBON. 171 The mixed C02 and CO are passed through a solution of sodium hydrate to absorb the C02, and the CO remains. One part of potassium ferrocyanide warmed with nine parts of H2S04 may be used to give the gas in nearly a pure, state. Its density is 14. It is almost insoluble in water, but soluble in a solution of cuprous chloride in ammonium hydrate. It burns in the air with a bluish- lavender flame, producing the higher oxide —C02. Owing to this property, it plays an important part in the reduction of ores m the blast furnace. It does not support combustion or respiration. It diffuses readily through red hot cast-iron, and frequently escapes from stoves and hot air furnaces. 277. Physiological Effects.—It has the power of combining with the haemoglobin of the blood and expelling the oxygen. It thus acts as a narcotic poison, causing dizziness, headache, nausea, incoordination of movements, convulsions, and death. If the carbon monoxide be in sufficient quantity to saturate all the haemoglobin, recovery is seldom, if ever, realized. The blood has a light red color, and does not coagulate or decompose as readily as normal blood. If the haemoglobin is only partially saturated, recovery may take place, but very slowly—debility, anorexia, etc., remaining for days. Air containing 0.5 per cent, kills birds m three minutes; 2 per cent, rendered a guinea pig insensible in two minutes. Artificial respiration is of little use.. Transfusion of blood is the most promising treatment. The sources of danger are open fires, defective draught in chimneys, escape of coal gas, and especially “ water gas,” from defective fittings or from leaks under the ground. When the ground is frozen and the gas escapes into the soil, near a cellar, the gas diffuses through the ground into the cellar, and, as it is thus deprived of its odor, persons may be poisoned and not know where it comes from. Goal gas poisoning is essentially a poisoning by the carbon mon- oxide which it contains. Suffocation by coal gas is not very different from suffocation by other gases. 278. Carbon Dioxide—Carbonic Anhydride (C02), sometimes called carbonic acid gas, is found free in the air in the proportion of about 4 parts per 10,000; and in ordinary well ventilated rooms from 5 to 6 parts per 10,000. It is found in volcanic gases, and in solution in many mineral springs. It sometimes accumulates in mines, wells and cellars, in dangerous quantities, and is then known as “ choke damp.” It may be de- tected in such places by lowering a candle. (See below.) It is produced when carbon or its compounds are burned with a free supply of air, by alcoholic and other fermentations, by the respi- 172 INORGANIC CHEMISTRY. ration of animals, and by slow oxidation of organic matter in the natural process of decay. In the laboratory it is obtained by the action of an acid upon a carbonate. CaC03 + 2HC1 = C02 + CaCl2 + H20. Carbon dioxide at ordinary temperatures and pressures is a colorless, transparent, odorless, tasteless, (by some sweetish), gas. Sp. gr. — 1.524. Density — 22. Under a pressure of 36 at- mospheres at 0°C.(32°F.), it is condensed to a colorless, mobile liquid, of sp. gr. 0.94. Above 32.5°C. it cannot be liquefied at any pressure. This is known as the critical point in temperature. When the liquid is exposed to the air it rapidly evaporates, pro- ducing a temperature so low as to freeze a portion of it to a snow- like solid; the temperature being sometimes as low as—130°C. (—202°F.). The gas extinguishes the combustion of burning bodies, and animals die very quickly in it. Death has resulted from persons entering mines, wells and fermenting vats, where the gas had accumulated. It is unsafe for a man to venture into a well or other place where a candle will not burn. C02is soluble in its own volume of water, at the ordinary temperature and pressure, forming a solution of carbonic acid (H2C03). Common soda water is a solution of the gas in water under pressure ; it con- tains no sodium salt, as its name would imply. 279. Physiological Effects.—These vary with the degree of concentration of the gas and its dilution with other gases. If the gas be pure, it causes death instantly, by apnoea from spasm of the glottis. When somewhat diluted, there is, at first, great loss of muscular power; the patient becomes livid, sinks down and dies without a struggle. When still more dilute, there is, at first, irritation of the throat, then giddiness, ringing in the ears, loss of muscular power, with rapid pulse and respiration, and occasionally vomiting and convulsions, finally ending in coma and death. The amount of the gas that can be tolerated in the air depends not only upon the quantity of it actually present, but also upon the source of it. Thus, when the source of the gas is animal respiration or combustion, the oxygen is withdrawn from the air at the same time, and a much smaller quantity will prove fatal than where the gas is simply added to the normal atmosphere. If the C02 is simply added to the air, 10 per cent, may be re- garded as poisonous, and even 8 per cent, will prove injurious. If, on the other hand, the oxygen be increased, an air containing CARBON. 173 even 20 per cent, may be breathed. A taper will burn in an air containing 8 per cent, of C02, provided the oxygen be present in normal quantity, and will burn feebly in such an air containing 10 per cent. Where the C02 is produced by combustion or respi- ration, the injurious effects are soon perceived, and are due to several causes; viz., the deficiency of oxygen, the presence of too great a quantity of C02 and moisture, the rise in temperature, and the action of the organic matter exhaled from the lungs and skin. The exposed air contains from 4 to 5 per cent., or about .78 cubic feet of C02 per hour, and there is absorbed .94 cubic feet °f oxygen. A stearin candle gives off .5 cu. ft. of C02, and uses up 1 cu. ft. of oxygen. A gas light burning 5 feet of gas per hour (12 candle power), gives off very nearly 6 cu. ft. of C02, or 3.7 times as much as one man ; as much heat as 2 men; removes more oxygen than 5 men; and gives off nearly as much watery vapor as 5 men. More than 6 parts of C02 per 10,000 of air renders it oppressive, and should not be allowed. Assuming the amount of C02 given off in an hour by an adult to be .7 cu. ft-, and normal air to contain 4 parts, it would require about 3500 cu. ft. of air per hour, in order that it should not receive uiore than two parts per 10,000 of C02, or 2 cubic feet. Dr. Parkes fixes the amount necessary at 2000 cu. ft. per hour. It is unpossible to change the air of a room oftener than 3 or 4 times per hour without causing uncomfortable draughts; and it would, therefore, require 700 to 1000 cu. ft. of room space, in order to keep the air of the room in a proper condition. If lights are used, which change the air, a corresponding calculation must be niade for them. A common oil lamp, or two sperm candles (not an argand lamp), will contaminate the air about the same as an adult man. The English Poor:Law Board’s requirements for dormitories, to prevent over-crowding, are— Cu. ft. 1200 Lying-in cases and offensive sick. 850 Sick. 700 Infirm. Same room night and day. 500 Infirm. Separate room in day. 300 Healthy. These figures are, of course, too small for general use. Parkes quotes Morin as giving the following amount of fresh air neces- sary to be furnished to each adult per hour in the following cir- cumstances :— 174 INORGANIC CHEMfSTRY Day. Night. In Barracks, 1059 cu. ft. per hour. 2118 cu. ft. per hour “ Workshops, 2118 “ “ “ Schools, 1059 “ “ “ “ “ Hospitals, 2825 “ “ “ “ In sleeping apartments, the amount of space allowed to each individual should be not less than 1000 feet, i. e., a room 10 X 10 X 10 ft.; but, as the proportion of carbonic dioxide would accumulate slowly, and as a much larger amount of the gas may be borne without serious discomfort, even one-half this capacity may be tolerated with little inconvenience beyond a feeling of fatigue or sleepiness in the morning. Dr. Tidy regards 400 cubic feet as the very smallest amount of space that should be allowed to each person in a sleeping room, to avoid serious overcrowding. The foulest air in an occupied room is at the ceiling. The heat of the body or a lamp causes an expansion of the air about them and an upward current of air, the heated C02, water vapor, etc. These gases reach the ceiling before they cool sufficiently to stop this upward current, and before there is time for perfect diffusion. The upper galleries in theatres are supplied with impure air from the main floor and lower galleries, and from the gas lights. Fresh air should always be admitted to a room near the floor, and the outlet for impure air should be at or near the ceiling. It must be remembered that the law of diffusion of gases does not allow the C02 to accumulate in one part of the room and remain there for any considerable time, but mixes them evenly. Nor is this diffusion confined within a room. It takes place through porous walls between the indoor and outdoor air, especially in winter, when there is much difference in the temperature of the two. Indeed, a very fair amount of ventilation may be effected in this way, where the walls are of brick or stone, and not painted or papered inside. Carbonic dioxide exists in the blood in solution, and does not combine with the corpuscles, the blood after death remaining dark-colored and liquid. Putrefaction after C02 poisoning is slow, while animal heat and rigidity are very persistent. 280. Tests for Carbon Dioxide.—If the quantity ex- ceeds 12 per cent., a taper is extinguished. Moistened litmus paper is first reddened, then bleached. Lime water or baryta water is rendered cloudy by it, from the precipitation of the carbonates of calcium or barium. 281. Carbonic Acid and Carbonates.—C02 is soluble in water, with which it combines to form carbonic acid (H2C03). H2O -f- C02 — H2CO3. CARBON. 175 Carbonic acid is a feeble, dibasic acid, forming a double series °f salts, the carbonates and acid or bi-carbonates. As Mentioned above, “ soda water ” is a solution of carbonic acid in water, kept under pressure. When the pressure is removed, a large portion of the acid undergoes decomposition into the anhy- dride (C02) and water. The same decomposition, with effer- vescence, takes place when we prepare the acid by treating a carbonate with a stronger acid. The carbonates of gold, arsenic, antimony and aluminum are unknown. The carbonates of the alkaline metals are soluble in water, and are not decomposed by heat; while the carbonates of all the other metals are insoluble and decomposed by heat into the oxides of the metals. The bi- carbonates are formed by passing carbonic dioxide through the solution of the carbonates. They are converted into the carbon- ates by heat. The carbonates of ammonium are volatilized by heat. Water charged with carbonic acid dissolves the carbonates of some of the metals, as calcium, magnesium, iron, copper, lead, etc., which gives rise, in the case of the first two, to hard water, hhis hardness is deposited again on boiling the solution, or even on free exposure to the air, thus forming an important element Jn certain geological formations. 282. Carbon and Sulphur—Carbon Disulphide (CS2), ls formed, like the dioxide, by the direct union of the elements. When the vapor of sulphur is passed over charcoal heated to redness, the two elements combine, producing vapors of carbon disulphide, which condense into a very volatile, colorless, mobile liquid, possessing a peculiar, disagreeable odor; it refracts light strongly, and for this reason is used to fill hollow glass prisms for the spectroscope. It is combustible, burning with a blue flame, and has been suggested as a means of furnishing sulphurous oxide tor fumigation, by burning a mixture of CS2 and alcohol in a lamp. fhe vapor mixed with air, forms an explosive mixture, and piixed with nitrous oxide, it burns with a very brilliant flame. It ls insoluble in wrater, but is miscible with alcohol and ether. It is a ready solvent for sulphur, phosphorus, caoutchouc (India rubber), tatty oils and iodine, with the last of which it forms a violet-red solution. CS2 dissolves in a solution of the alkaline sulphides form- ing sulpho-carbonates, CS2 + K2S = K2CS3. CS2 may be re- garded as the anhydride of sulpho-carbonic acid, H2CS3, obtained ny adding hydrochloric acid to a sulpho-carbonate. Carbon Monosulphide (CS)—a brown-red powder, and a sulphide hav- ing the formula C5S2, and an oxy-sulphide, COS, are also known. 176 INORGANIC CHEMISTRY. CARBON AND NITROGEN. Cyanogen (C2N2) = 52. 283. History and Preparation. — Discovered by Gay Lussac in 1815. It was the first compound radical isolated. Although carbon and nitrogen cannot be made to unite directly, yet carbon compounds containing nitrogen, when heated with potassium hydrate, yield potassium cyanide (KCN), and, in the presence of iron, form potassium ferrocyanide, or yellow prussiate of potash. From these two compounds all the long list of compounds containing the radical CN are prepared. Cyanogen is most easily prepared by heating mercuric or ar- gentic cyanide ; or, a mixture of two parts well dried potassium ferrocyanide and three parts of mercuric chloride. 284. Properties.—Cyanogen is a colorless gas, possessing a pungent odor. It is soluble in one-fourth its volume of water, and one-twentieth its volume of alcohol It is easily condensed to a liquid at — 20.7°C., or at ordinary temperatures by a pressure of 4 atmospheres. At —34°C. (—29.2°F.) it freezes to an ice- like solid. It burns in the air with a purple-red flame. The free cyanogen molecule is composed of two cyanogen radicals, CN— CN. The radical CN— is a monad negative, or acid radical, resembling the chlorine group in its chemical behavior, and forming a series of cyanides resembling the chlorides, thus :— Symbol Cy. Density = 26. Sp. gr. = 1.8. Potassium chloride KC1. Silver chloride AgCl. Mercuric chloride HgCl2. Potassium cyanide KCy. Silver cyanide AgCy. Mercuric cyanide HgCy2. 285. Hydrocyanic Acid—Prussic Acid (HCy), is most readily obtained by decomposing the metallic cyanides with sul- phuric or hydrochloric acid. KCy + H2S04 = HCy + KHS04. AgCy + HC1 = AgCl + HCy. The acid boils at 26.5°C. (79.7°F.), and is soluble in water, from which it gradually escapes. It is a colorless liquid, of a charac- teristic odor and taste, resembling those of bitter almonds, the oil of which contains from 5 to 14 per cent, of this acid. It is also a constituent of peach kernels and cherry-laurel water. Acidum Hydrocyanicum Dilutum (U. S. P. and B. P.) contains two per cent, of HCy, while the French Pharmacopoeia directs the acid to contain 10 per cent. 286. Cyanides.—Prussic acid forms a series of binary com- pounds known as cyanides, which resemble the haloid com- CYANOGEN. 177 pounds. Like the acid, they are all more or less poisonous. The cyanides of potassium, mercury and silver are best known. The first is soluble in water, the other two are insoluble. The potassium salt is used largely in photography and in electro- metallurgy. 287. Toxicology.—Hydrocyanic acid and the cyanides are very poisonous. One drop of the pure acid is enough to cause instant death. Accidents are liable to occur from the use of the cyanides, or from the acid, or vegetable substances containing nmygdalin, a body which easily undergoes decomposition into prussic acid and other products. Bitter almonds, cherry-laurel, the pits of the common cherry, plum, peach and sloe, may be mentioned as the most common of these. In England, poisoning hy cyanides ranks second in order of frequency, in all cases of poisoning. One grain of TIGy and 2.4 grains of potassium cya- nide are sufficient to cause death in man. The symptoms of poisoning by HCy and KCy are very nearly the same—first a salivation, then constriction of the throat, giddiness, insensibility; the person then falls, usually in a convulsion, respiration and pulse become irregular, and finally cease. The symptoms com- mence from ten seconds to one minute after swallowing of the poison, depending somewhat upon the dose and form of admin- istration. In some cases death is almost instantaneous; in others, 1t is prolonged to 15 minutes, or longer. Hydrocyanic acid enters the blood, forming a compound with the haemoglobin, passes to the medulla and paralyzes the respiratory centres. The post- mortem appearances are mainly those of suffocation, and every- where there is the odor of the acid, unless concealed by putrefactive odors. When potassium cyanide has been used, there ls usually inflammation of the stomach, due to its caustic action. 288. Chronic Poisoning by Cyanides may occur in photographers, gilders and electro-platers. The symptoms are headache, giddiness, noises in the ears, pain in the region of the heart, difficult respiration, loss of appetite, nausea, obstinate con- stipation, full pulse, pallor and offensive breath. . 289. Treatment.—When there is time, cold douches, ammo- uia inhalations, chloride of lime alone or moistened with vinegar und held to the nose, frictions, electricity, artificial respiration. I he best antidote is a mixture of ferrous and ferric sulphates, with sodium or potassium hydrate or carbonate. Usually, however, there.is not sufficient time to apply these remedies, except in cases °f poisoning by the vegetable substances above mentioned as containing it, and in chronic poisoning. 178 INORGANIC CHEMISTRY. 290. Tests.—1st. Silver nitrate precipitates the acid as silver cyanide—a white, curdy precipitate, insoluble in nitric acid.. A rod moistened with AgN03 and held in the vapor, is rendered milky. 2d. Add a solution of liquor potassae, or potassium hydrate, then a solution of ferrous sulphate mixed with ferric sulphate, then a small quantity of sulphuric acid, when a blue deposit of Prussian blue will appear. 3d. To a small portion of the suspected liquid, in a wide test tube or crucible, add dilute sulphuric or hydrochloric acid. Invert over this a watch glass, convex side down, with one or two drops of yellow ammonium sulphide upon the under side of it. Warm the crucible gently, and after a few minutes remove the watch glass, warm, and evaporate the ammonium sulphide by blowing upon it. Now touch the stain with a drop of ferric chloride, when a blood-red stain will make its appearance, due to the formation of sulpho- cyanate of ammonium on the glass, which, with the iron, strikes a red color. This is easy to perform, is applicable to organic mixtures, and is quite delicate. 291. Cyanic Acid (H-O-Cy).—Metallic cyanides readily take up oxygen, when fused with oxidizing agents, such as po- tassium nitrate, or even the oxides of some of the metals, and form cyanates. The acid, IiOCy, may be prepared by decomposing its salts with dilute acids, but it is unstable, and breaks up into carbon dioxide and ammonia. HOCN + H20 = NH3 + C02. Of the cyanates, the ammonium cyanate is the most interesting, as its solution in water, on being heated, forms urea, a body isomeric with it, and a well known excretory substance found in urine. NH4CN0 = CO(NH2)2. This is interesting as being the first animal substance prepared by synthesis. 292. Sulphocyanates.—The potassium salt is prepared by fusing potassium ferrocyanide and sulphur together, and ex- hausting the fused mass with alcohol. On evaporating the alcohol, a white, crystalline’ salt is obtained, soluble in water, and having the formula KSCy. Ammonium Sulphocyanate (NH4SCy) is prepared by heating hydrocyanic acid with yellow ammonium sulphide. The principal interest attached to these salts is as tests for ferric iron salts, with which they give a blood-red solution. Mercuric sulphocyanate, formed by precipitating mercuric 179 nitrate with potassium sulphocyanate, is decomposed by heat, the niass swelling up and leaving a voluminous residue. It is used in making the toy, Pharaoh’s Serpents. 293. Compound Cyanides.—Cyanogen shows a remarkable tendency to form complex compounds. Among these more complex compounds are two series of bodies in which cyanogen and iron form the radical. Of these, the ferrocyanides and ferricyanides of potassium and iron will be mentioned here. Potassium Ferrocyanide—K4(FeCy6)—Yellow Prus- siate of Potash, is an important commercial product, manu- factured on a large scale by fusing in a closed crucible nitrogenous animal matter (horns, hoofs, leather scraps, etc.), with potassium carbonate and iron filings, treating the fused mass with water, and crystallizing. The salt is thus obtained in large, yellow, tabular crystals. It is used in dyeing, in preparing certain pigments, and as a source of all the other cyanogen compounds. By simple fusion, potassium cyanide (KCy) is prepared. CYANOGEN. K4FeCy6 — 4KCy + FeC2 + N2. From a solution of the salt, various other ferrocyanides are prepared by precipitation. Of these, Prussian Blue (ferric ferrocyanide), prepared by adding to a solution of potassium ferrocyanide a solution of some ferric salt, is used as a pigment find as a medicine. With a ferrous salt the precipitate is white, but quickly becomes blue by oxidation. This test serves to distinguish ferrous from ferric salts. With cupric salts we obtain a reddish-brown precipitate, Cu2FeCy6. Ferricyanides.—By passing chlorine through a solution of K4FeCys, a compound is formed in which the iron of the radical is tetrad, and the radical itself becomes hexad. K6 (Fe2Cy12)VI. On evaporating, we obtain dark red crystals of potassium ferricyanide, or red prussiate of potash. With ferrous salts a solution of this salt gives a deep blue precipitate of ferrous ferricyanide—Fe3Fe2Cy]2—Turnbull’s Blue. Ferric salts give no precipitate or coloration, and thus we distinguish ferric from ferrous salts. Ferric Ferrous cyanide = Prussian Blue. Ferrous Ferric cyanide = Turnbull’s Blue The further consideration of carbon compounds will be con- sidered in part third. 180 INORGANIC CHEMISTRY. THE ALKALINE METALS. 1. Lithium 7 2. Sodium 23 3. Potassium 39 4. Rubidium 85.5 5. Caesium 132.6 6. (Ammonium)... 294. The metals of this group present great similarity in their chemical and physical properties. Exposed to the air, they all oxidize readily. They decompose water violently, with the forma- tion of strong basic hydrates which dissolve in the excess of water. The hydrates thus formed are called caustic alkalies (caustic potash, caustic soda); hence the name, alkaline metal. Nearly all of the salts of these metals are soluble, and most of them, when in solution, turn blue litmus red. They form but one chloride, one iodide and one bromide. LITHIUM. 295. Lithium occurs widely distributed in nature, but in small quantities. It is found in some mineral springs and in the ashes of many plants, chiefly that of tobacco and beet. It is usually obtained by separating it from its chloride by electrolysis. It is silver-white in color, and decomposes water at ordinary tempera- tures. It is the lightest of the solid elements,—sp. gr. 0.589,—and floats upon naphtha. It fuses at 180°C. (856°F.), and burns in air with an intense red light. Its salts closely resemble those of sodium. Lithium Oxide (Li20) is a white solid, formed by burning lithium in dry oxygen. It slowly dissolves in water, forming the hydrate, LiOII. Lithium Chloride (LiCl) crystallizes at ordinary tempera- tures, in regular, anhydrous octahedra; below 10°C. (50°F.), however, with two molecules of water. It is very deliquescent. 298. Lithium Bromide (LiBr) is obtained by decomposing lithium sulphate with potassium bromide; or, by neutralizing a solution of hydrobromic acid with lithium carbonate. It crys- tallizes in deliquescent needles. 297. Lithium Carbonate—Lithium Carbonas (U. S.), (LbCCV), is obtained by fusing a native silicate called lepidolite, with barium sulphate and carbonate, and potassium sulphate. It is then extracted with water, and precipitated with sodium carbonate. It is a white, odorless powder, of a strongly alkaline taste, soluble in water to the extent of 12 parts per 100. It unites readily with uric acid, forming a soluble lithium urate. It Li = 7. SODIUM. 181 is said that 250 parts of lithium carbonate at a temperature of 38°C. (100.4°F.), will dissolve almost 1000 parts of uric acid. This property renders it of value in diminishing the deposit of uric acid formed in gout, and in dissolving uric acid calculi. SODIUM—Natrium 298. Occurrence.—This metal occurs widely distributed, being found in sea-water and in rock salt as chloride, and in many native silicates. 299. Preparation.—Like potassium, it is obtained by a pro- cess which depends upon the reduction of the carbonate by coal. -The two substances are mixed in an iron retort, and heated to redness. Na = 23. Na2C03 + 2C = 2Na + 3C0. 300. Properties.—Sodium is a soft, silver-white metal, re- sembling potassium, but less easily oxidized. It becomes slowly coated with a brownish-yellow layer on exposure to the air, and should be kept under naphtha. It fuses at 95.6°C. (203.8°F.), and volatilizes at a white heat, the vapor burning with a bright yellow flame. Sp. gr. 2.078. It is characterized by its affinity for oxygen, decomposing water at ordinary temperatures, liberat- ing hydrogen, and forming sodium hydrate. 301. Oxides.—Three are described—Na20, Na40, Na202. I he first of these is a white powder, formed by the oxidation of the metal in dry air. It is very deliquescent, soon liquefying in air. The peroxide is a grayish-white mass, obtained by burning sodium in a current of oxygen. They all unite with water with great energy. 302. Sodium Hydrate—Caustic Soda—Soda (U. S., y.r-)> (NaOH), is usually obtained by boiling a solution of so- dium carbonate with calcium hydrate. lhe resulting solution, after filtering, is evaporated to dryness, dissolved in alcohol, again evaporated, fused in a silver vessel, and cast into sticks. This product is usually labeled caustic soda by alcohol. It is a white, opaque, brittle, crystalline mass, fusing below redness; sp. gr. 2.00. It dissolves readily in Water, the solution being known as soda lye in the arts, and in pharmacy, as liquor sodae (sp. gr. of latter 1.071). This solu- tion attacks glass; hence, the necks and stoppers of bottles con- taining it should be coated with paraffine. When exposed to the Na2C03 + Ca (0H)2 = CaC03 + 2NaOH. 182 INORGANIC CHEMISTRY. air, sodium hydrate attracts water and carbonic dioxide, and is converted into the carbonate. 303. Sodium Chloride—Common Salt—Sodii Chlori- dum (U. S., Br.), (NaCl), is found very abundant in nature. It is deposited in almost all parts of the globe in the solid form as rock salt; in solution, it is found in all natural waters, and to the extent of 2.7 to 3.2 per cent, in sea water; it also exists in most animal and vegetable tissues. It is formed in a great number of chemical reactions. Its most important source is the deposits of rock salt, from which it is mined; it is also obtained by the evaporation of sea or saline spring waters. It crystallizes from water in translucent cubes. Sp. gr. 2.078. It fuses at a red heat, and volatilizes at a white heat. Hot water dissolves but little more than cold; 100 parts of water at 0°C. (32°F.) dissolve 36 parts of the salt; and at 100°C. (212°F.), 39 parts. A satu- rated solution, therefore, contains 26 per cent, sodium chloride. From dilute solutions nearly pure ice is obtained by freezing. On account of a slight admixture of magnesium salts, most speci- mens of common salt will deliquesce; the perfectly pure salt, however, is not hygroscopic. 304. Sodium Bromide (Na Br) is formed by the action of bromine upon a solution of sodium hydrate. It crystallizes in anhydrous cubes, and is soluble in 1.13 parts of water at 20°C. (68°F.), and in 0.87 at 100°C. (212°F.) It contains 77.67 per cent, of bromine. 305. Sodium Iodide (Nal) also crystallizes in cubes without water; and is soluble in 0.56 parts of water at 20°C. (68°F.), and in 0.32 at 100°C. (212°F.) It contains 84.66 per cent, iodine. 306. Sodium Sulphate—Neutral Sodium Sulphate— Glauber’s Salt Sodii Sulphas (U. S.)—Sodae Sulphas (Br.)—(Na2S04), occurs native in deposits; also in solution in mineral waters. It is a by-product in the manufacture of sodium chloride from sea water and brine, and in several manufacturing industries. It is prepared by the decomposition of common salt with sulphuric acid. 2NaCl + II2S04 = Na2S04 + 2HC1 Sodium sulphate crystallizes, at ordinary temperatures, with two proportions of water (7 aq. and 10 aq.) in large, colorless, monoclinic prism3, which effloresce in the air, losing all of their water. If heated to 33°C. (91.4°F.) it fuses in its own water of crystallization, and at higher temperatures becomes anhydrous. The following curious action of the solution of Glauber’s salt may also be noticed: If the solution, saturated at 33°C. (91.4°F.), be cooled down SODIUM. 183 to the ordinary temperature, and even far below, no separation of crystals occurs, although the salt is very much more insoluble at lower temperatures than at 33°C. (91.4°P.). This formation of a supersaturated solution ls common to many salts, though not to so marked a degree as in the case °f Glauber’s salt. This supersaturated solution may be agitated, and still no crystals form. But, if it be gently touched with a glass rod or some other solid body, the entire mass will at once become crystallized. 307. Hydro-Sodium Sulphate—Acid Sodium Sulphate '—Sodium Bisulphate (NaHS04), is obtained by the action of sulphuric acid upon sodium sulphate, or sodium chloride. NaCl + H2S04 = NaHS04 + HC1. It crystallizes in long, four-sided prison. It fuses readily, and at higher temperatures loses water and is converted into the Pyrosulphate Na2S207. Very soluble in water, giving an acid solution. 308. Sodium Hyposulphite—Sodium Thiosulphate (Na2S203), is prepared by boiling the sulphite with sulphur. It forms large monoclinic prisms, which contain 5 molecules of Water, and is slightly deliquescent in the air. It is used as a reducing agent, decoloring an iodine solution with the formation °f sulphuric acid and sodium iodide. 30b. Sodium Carbonate—Soda—Neutral Carbonate of Soda—Sal Soda—Washing Soda—Sodii Carbonas (U.S.) ~~Sodae Carbonas (Br.), (Na2C03), is the most important of the sodium compounds, for industrial purposes. It occurs abund- antly in nature, in the so-called sodium seas (in Egypt, and the Caspian Sea), and is contained in the ashes of many sea plants, chiefly the algse. The principal supply is sodium chloride, from which it is manufactured according to a method devised by Leblanc, in 1808. By this method the sodium chloride is first converted into sulphate by warming with sulphuric acid. The sulphate, when dried, is mixed with charcoal and calcium car- bonate, and strongly heated. Two reactions take place during this process: First, the carbon reduces the sodium sulphate to sulphide. Na2S03 + S = Na2S203. Second, the sodium sulphide and calcium carbonate react to lorm calcium sulphide and sodium carbonate. Na2S04 + 2C = Na2S + 2C02. The high temperature also converts a portion of the calcium carbonate into calcium oxide and carbon dioxide. The products Na2S + CaC03 = CaS + Na2C03. 184 INORGANIC CHEMISTRY. of this fusion, known as black ball soda, are, therefore, sodium carbonate, calcium sulphide and calcium oxide. The black ball is broken up and lixiviated with hot water, which dissolves out the sodium carbonate ; this solution is evaporated to dryness, and crude soda ash, or soda, of commerce results. Of late years another process, known as Solvay’s, or the am- monia method, has largely replaced that of Leblanc. In this process, ammonium bicarbonate reacts upon sodium chloride, forming the sparingly soluble sodium bicarbonate, and the freely soluble ammonium chloride. The sodium bicarbonate is then converted into the carbonate by heat. At ordinary tempera- tures, sodium carbonate crystallizes in large, rhombic crystals, containing 10 molecules of water, which effloresce in dry air. It is soluble in water, most freely at 38°C. (100.4°F.) Its solutions have an alkaline reaction. When the crystals are calcined at a dull red heat, they disintegrate, give off their water of crystal- lization, and form a white powder, the sodii carbonas ex- siccata, of the U. S. P. 100 parts of H.,0 dissolve 10 parts of this anhydrous carbonate at 0°C. (32°F.), and 138 parts at 38°C. (100.4°F.). 310. Hydrogen Sodium Carbonate—Acid Sodium Carbonate—Sodium Bicarbonate—Sodii Bicarbonas (U. S.)—Sodae Bicarbonas (Br.), (NaHC03J, is found in many mineral waters. It is produced by the ammonia process as above, and by the action of carbon dioxide upon sodium carbonate. Na2C03 + C02 +H20 = 2NaHC03. It forms small, rectangular prisms, which are anhydrous, but dissolve in ten or eleven parts of water. Its solutions are nearly neutral to test paper. By heating the solid or boiling its solu- tions, it gives off carbon dioxide and is converted into the carbonate. 313. Sodium Phosphates.—These are three in number. They are less soluble and crystallize better than the potassium salts of phosphoric acid. The tri-sodium phosphate, or basic phosphate (NasP04), is made by saturating 1 part of phosphoric acid with 3 parts of sodium hydrate. It crystallizes in six-sided prisms, and is soluble in 5.1 parts of water at 15.5°C. (59.9°F.) Its solution is alka- line to test paper. Hydrogen Disodium Phosphate—Disodium Phos- phate—Neutral Sodium Phosphate—Sodii Phosphas (U. S.)—Sodse Phosphas (Br.), (Na2HP04), is more stable SODIUM. 185 than the other phosphates, and is the one generally employed in medicine and in laboratories. It may be prepared by treating phosphoric acid with sodium hydrate to feeble alkaline reaction. Below 30°C. (86°F.) it crystallizes in large, rhombic prisms, with 12 Aq.; at 33°C. (91.4°F.) it crystallizes with 7 Aq. The salt with 12 Aq. effloresces in air, losing 5 Aq.; that with 7 Aq. does not. Both are freely soluble in water, and show a faintly alkaline reaction. Monosodium Phosphate—Acid Sodium Phosphate (NaH2P04), crystallizes in rhombic prisms with 1 molecule of water, and is acid in reaction. At 100°C. (212°F.) it loses its Water of crystallization, and at about 200°C. (392°F.) forms sodium pyrophosphate (Na2H2P207), and at 240°C. (464°F.) the metaphosphate (NaP03). Na2H2P207 = 2NaP03 + H20. 312. Sodium Nitrate—Chili Saltpetre—Sodii Nitras (U. s.), (NaNOa), is found native in extensive deposits in Peru, it crystallizes in rhombohedra, which closely resemble cubes ; lienee, it is called cubic saltpetre. It is deliquescent, and is, there- fore, not adapted for the manufacture of gunpowder; it has a cooling, saline, somewhat bitter taste. It is more readily soluble in water than potassium nitrate, which, in other respects, it quite closely resembles (which see). It is used in the manufacture of nitric acid, and as a fertilizer. . 313. Sodium Borates.—Six are known. The only one of importance is the Disodium Tetraborate—Sodium Pyro- borate—Borax—Tincal—Sodii Boras (U. S.), (Na2B407), which is found native in some of the lakes of Thibet, from which country it was formerly imported. At present it is prepared artificially by boiling boric acid with sodium carbonate. Boric acid is found in lagoons of Tuscany, and this is the present source. It crystallizes in large, hexagonal prisms, with 10 molecules of H20, or in regular octahedra with blXjO. The former variety effloresces in dry air; the latter is permanent. Both dissolve in 12 parts of cold and 2 parts of boiling water, forming a solution that has a feebly alkaline reaction. Upon heating, both salts puff up considerably, lose their water, and form a white, porous mass (burned borax), which finally fuses to a transparent glass. In the fused state, it will dissolve many metallic oxides, forming clear glasses (borax beads), which often show a characteristic color on cooling; thus, copper salts give a blue, and chromic oxide an emerald green 186 INORGANIC CHEMISTRY. glass. Borax is used in this way as a blowpipe test for certain metals. It is this property of dissolving oxides of the metals that renders borax useful in welding and soldering metals. In these operations it is used to remove the oxide, or rust, from the sur- faces of the metals. 314. Sodium Hypochlorite (NaCIO).—When in solution Liq. Sodse Chloratse (U. S.), (Br.)—Labarraque’s solution. It may be prepared by decomposing a solution of chloride of lime with sodium carbonate. It yields up its chlorine readily, thus acting as an efficient disinfecting and decolorizing agent. 315. Physiological Effects of the Sodium and Potas- sium Compounds.—The action of the halogen salts of these metals is generally that of the combined chlorine, bromine, or iodine. The hydrates of both metals, and, to a lesser degree, the carbonates, tend to disintegrate the tissues with which they come in contact; hence, they possess powerful caustic properties. If taken internally, the hydrates are highly poisonous, causing death, like the mineral acids, either immediately, by their corrosive properties, or secondarily, by exciting inflammation of the gastro- intestinal mucous membrane, with consequent thickening and constriction. In cases of poisoning by the caustic alkalies, the stomach should be evacuated, and a weak acid, such as dilute vinegar or lemon juice, given, to neutralize the alkali; or, it should be saponified by the administration of some oil or fat. The nitrate of these metals is also toxic in its influ- ence, and for it there is no direct antidote. The alkaline carbonates are, undoubtedly, of considerable importance to the carrying on of the normal functions of the animal body. In the first place, it is exceedingly probable that some, at least, of the albuminoid matters of the blood are held in solution by reason of its alkaline reaction, which is largely given it by these carbonates. Secondly, it has been shown very clearly that the alkaline reaction of the blood is of first importance to the oxidation processes, which are intimately connected with the production of animal heat and retrograde metamorphosis. It is only in the presence of a free alkali that many organic substances will unite with oxygen, and thus, their decomposition without an alkali would be impossible at the temperature of the body. In proof of this, it is known that, if the vegetable acids are given free, they will reappear, for the most part, unchanged, in the urine ; but if they are in combination with the alkalies when given, they are thoroughly burned up in the blood, and reappear as carbonates. In fact, so important are these alkaline salts—carbonates and phosphates—that without them, albuminoid bodies will not support life. The alkaline carbonates in sufficient quantity render the urine rOTASSIUM. 187 alkaline in reaction and increase the quantity. The tartrates, citrates and acetates of sodium and potassium have a very similar action upon the economy to that of the carbonates, into which they are converted either in the intestines or blood. A slightly uiore cathartic action is attributed to the tartrates than is pos- sessed by the carbonates. This action is also more or less shown by the sulphates and phosphates. POTASSIUM (Kalium). 31G. Occurrence.—This metal is found widely distributed in rocks and minerals, principally as silicates. By the action of the atmosphere and other influences, these silicates gradually decom- pose, the potassium passes into the soil and is absorbed by the plants, from the ashe3 of which it may be obtained. The chlo- ride and sulphate are also found in sea-water, and in large deposits, mixed with other chlorides. A chloride of potassium is mined in Stassfurth, Germany, as a source of potassium salts. 317. Preparation and Properties.—It is prepared by calcining an intimate mixture of the carbonate with carbon. K = 39, K2C03 + 2C = 2K -f 3C0. Such a mixture may be made by heating organic potassium salts, as crude tartar, to redness. In this way a black mass is formed, consisting of potassium carbonate and free carbon. By heating this black mass to a white heat in an iron retort, the potassium distills off', and is condensed under mineral naphtha. Potassium is a silver-white, lustrous metal, brittle at 0°C. waxy at 15°C. (59’F.), fuses at 623C. (113.6’F.), and distills at a red heat. Sp. gr. at 15°C. (59’F.) = 0.865. Its affinity for oxygen is such that, if it be exposed to the air, it tarnishes at once. It decomposes water or ice with great energy, with the formation of potassium hydrate and the liberation of hyd rogen, which is ignited by the high temperature caused by the reaction. It combines directly and energetically with the halogens, sulphur, phosphorus, arsenic, antimony and tin. 318. Potassium with Oxygen—Potassium Oxide (K20), results from the direct oxidation of potassium, by simply exposing thin strips of the metal to dry air, or by the action of potassium upon the hydrates. 2K0H + K2 = 2K20 + H2. 188 INORGANIC CHEMISTRY. It is a Avhite, deliquescent, caustic powder, uniting readily Avith water to form the hydrate, with the evolution of much heat. 319. Potassium Hydrate—Caustic Potash or Potassa (U. S.), Potassa Caustica (Br.), (KOH), is prepared by the decomposition of potassium carbonate by calcium hydrate (slacked lime). K2C03 + Ca(OH)2 = CaC03 + 2KOH. After these substances have been boiled together, the solution is allowed to settle. It is then poured off, evaporated, and the residue fused in a silver dish (which it does not attack). The fused mass is then poured into moulds. This is called potash by lime, and is not pure. To render it purer it is dissolved in alcohol, the solution evaporated to dryness, the residue again melted and east in silver moulds ; this product is potash by alcohol, and is free from the chloride and other potassium salts. It is a white, opaque, brittle solid, usually met with in the form of cylindrical sticks, but sometimes in lump. It has a specific gravity of 2.1. It fuses quite easily, and, at high temperatures, volatilizes undeeomposed. It is freely soluble in water; less so in alcohol. The solutions give a markedly alkaline reaction, saponify fats, and are strongly caustic. Exposed to the air it absorbs water and carbon dioxide, and is changed into the carbonate. In watery solution it is largely used as a reagent in chemical analysis; it dissolves chlorine, bro- mine, iodine, sulphur and phosphorus. It decomposes the am- moniacal salts, liberating ammonia; it also decomposes the salts of many of the metals, with the formation of a potassium salt and a hydrate of the metal. The haloid salts of potassium form by direct union of the haloids with the metal, or by saturating the hydrate or carbonate with one of the haloid acids. They all have a bitter, salty taste, are freely soluble in water, and crystallize in cubes. They fuse easily, and are somewhat volatile. 320. Potassium Chloride (KC1), occurs native, either pure or mixed with other chlorides. At Stassfurth it is found in large deposits, as sylvite, and carnallite (KCl.MgCb.CH./)). These deposits form the chief source of the potassium compounds. The chloride crystallizes in anhydrous cubes, of sp. gr. 1.84, clcsely resembling common salt. 100 parts of water dissolve 30 parts at 0°C. (32°F.), and 0.2738 part more for every degree elevation of temperature. 321. Potassium Bromide—Potassii Bromidum (U. S., Br.), (KBr), is generally obtained by dissolving bromine in a solution of potassium hydrate ; the bromate also produced in the POTASSIUM. 189 reaction is converted into bromide by calcining the product. It bas the properties of the other haloid salts, and is used in photography, and in medicine. 322. Potassium Iodide—Potassii Iodidum (U. S., Br.), (Kl), may be prepared like the preceding, by using iodine instead of bromine. It crystallizes in large, white, translucent cubes, permanent in air, and salty in taste. It dissolves to the extent of 100 parts in 73.5 parts water at ordinary temperatures. Its aqueous solution dissolves iodine in large quantities, forming the compound tincture of iodine. It also dissolves many metallic iodides to form double iodides. Its medicinal effects are those of iodine. In chronic poisoning by lead or mercury, it is sup- posed that it unites with the metals in the blood or tissues, to form soluble iodides, and thus pass them out by the urine. 323. Potassium Fluoride (KF1).—Its aqueous solution attacks glass. Is not of much importance to the medical student. 324. Potassium Cyanide (KCN), may be obtained either by saturating potassium hydrate with hydrocyanic acid, or by beating potassium ferrocyanide. It is a white, amorphous, deli- quescent mass, easily fusible, and smelling of prussic acid. Its solution is very poisonous. Its effects upon the economy are uncertain, but are probably those of hydrocyanic acid. In case of poisoning by it, the stomach should be evacuated and the antidotes of hydrocyanic acid given. Ferrocyanide and Ferricyanide—see page 179, Art. 293. 325. Potassium Chlorate—Potassii Chloras (U. S. P.), (KCL03).—When a hot, concentrated, solution of potassium hydrate is treated with chlorine gas, the following reaction occurs— 6K0H + 3C12 = 6KC1 + KC103 + 3H20. It is usually made hy the action of chlorine upon a mixture of calcium hydrate and potassium chloride. By this method a double reaction takes place. Calcium chlorate is first formed. 6Ca(OII)2 + 6C12 = 5CaCl2 + Ca(C103) + GH20. This then reacts with the potassium chloride. Ca(C103)2 + 2KC1 = 2KC103 + CaCl2. The hot solution is rapidly evaporated, and the residue purified hy recrystallization. It crystallizes in shining, transparent plates ot the monoclinic system. Soluble in water to the extent of G.03 parts in 100 at 15.37°C. (59.65°F.), and 24 parts at 104.7°C. (,220.5°F.); soluble with difficulty in alcohol. It is cooling and 190 INORGANIC CHEMISTRY. astringent to the taste, fuses at 400°C. (752°F.), giving up a portion of its oxygen and changing to the perchlorate (KC104), which at higher temperatures decomposes into oxygen and potassium chloride. As it gives up oxygen easily, it serves as a valuable oxidizing agent, and as a means of preparing this gas. Mixed with readily oxidizable substances, as carbon, sulphur, phosphorus, sugar, tannin, resins, etc., the mixtures explode when heated or subjected to a sudden shock. The igniting ma- terial with which parlor matches are tipped, consists of antimony sulphide and potassium chlorate; rubbed upon a surface coated with red phosphorus, they ignite. 326. Potassium Hypochlorite (KCIO), is formed by the action of chlorine upon a cold solution of potassium hydrate. It can only be obtained in aqueous solution. If the solution is evaporated, the salt splits up into chloride and chlorate. 2KH0 -f- Cl2 = KOI +KC10 + H20. When treated with acids, it yields free chlorine and bleaches strongly. The ordinarysolutions used in bleaching (Labarraque’s solution and Javelle water), are solutions of impure sodium or potassium hypochlorite. 327. Potassium Nitrate—Nitre—Saltpetre—Potassii Nitras (U.S.). (KN03), exists native,and is produced artificially whenever nitrogenous organic substances decay in the presence of potassium carbonate. Upon the so-called saltpetre planta- tions, manures and various animal refuse are arranged in layers Avith wood ashes and lime, in large heaps, and submitted to the action of the air for two or three years, whereby, from the slow oxidation of the nitrogen, nitrates of potassium and calcium are produced. The heaps are then lixiviated with water and potas- sium carbonate added to the solution, which contains potassium and calcium nitrates, to convert the last salt into potassium nitrate. 3KC10 = 2KC1 + KC103. Ca(N03)2 + K2C03 = CaC03 f 2KN03. The calcium carbonate is filtered off, and the solution evaporated. Another method, and probably the one most frequently em- ployed at present, consists in the decomposition of Chili salt- petre, sodium nitrate, by means of potassium carbonate, or chloride. NaNOs + KC1 — NaCl + KN03. It crystallizes in large, six-sided, rhombic prisms. 100 parts of POTASSIUM. 191 Water dissolve 244 parts of the salt at 100°C. (212°F.), but at 0° C. (32°F.) only 13 parts. It fuses at 350°C. (662°F.) : below a red heat it decomposes into oxygen and potassium nitrite, KN02. . The readiness with which it gives up its oxygen when heated 111 the presence of an oxidizable substance, renders it of value as an oxidizing agent. Gunpowder is a granular mixture of potassium nitrate, sulphur and charcoal, in such proportion that the nitre contains all the oxygen neces- sary for the combustion. The following equation expresses approxi- mately the decomposition caused by the burning of powder—- The effect produced, therefore, depends upon the disengagement of carbon dioxide and nitrogen, the volume of which gases is almost 100 times greater than that of the decomposed powder. The heat of the combustion further expands the gases at the time of the explosion. 328. Potassium Carbonate—Potassii Carbonas (U. S.) -Potassae Carbonas (Br.)—Salt of Tartar—Pearlash— (K2C03) ,—exists in mineral waters, in the animal economy, and as the principal ingredient of wood ashes. The plants absorb potassium salts from the earth and convert them into salts of the organic acids. When the plants are burned, the organic acids are destroyed and potassium carbonate produced, which is obtained by lixiviation of the ashes, and evaporation. This method is not much employed at present. The immense de- posits in Stassfurth and Gallicia afford an almost inexhaustible supply of potassium salts. It occurs commercially as a white, granular, deliquescent powder, freely soluble in water, the solu- tion having a caustic taste and an alkaline reaction. 329. Potassium Bicarbonate—Hydropotassic Carbon- ic—Potassii Bicarbonas (U. S.)—Potassae Bicarbonas (Br.), (KHCO:j).—When carbon dioxide is passed through a concentrated solution of potassium carbonate, it is absorbed and potassium bicarbonate produced. 2KN03 + S + 3C = K2S + 3C02 + N2. K2C03 + H,0 + C02 = 2KHC03. Fhis salt crystallizes in oblique, rhombic prisms, of the monoclinic system. It dissolves in 3 to 4 parts of water ; the solution is faintly alkaline but not caustic. The substance that is still extensively used in some parts of the country in baking, under the name saleratus, is this, or the corresponding sodium salt. It “ raises ” the bread by the action of heat in setting free the carbon dioxide, and leaving potassium (or sodium) carbonate, which, by its strongly alkaline reaction, may cause digestive disturbances. 192 INORGANIC CHEMISTRY. 330. Sulphides.—Five are known: K2S, K2S2, K2S3, K2S4, and K2S5; also a sulphydrate, KSH. The latter is prepared by the action of hydrogen sulphide upon potassium hydrate. KOH + H2S = KSH + H20. The Pentasulphide (K2 S3), Liver of Sulphur—Potassii Sulphuretum (U. S.)— Potassa Sulphurata (Br.), is ob- tained by fusing potassium carbonate with an excess of sulphur. It decomposes readily, and in contact with hydrochloric acid gives off hydrogen sulphide. 331. Potassium Sulphate—Dipotassium Sulphate— Potassii Sulphas (U. S.)—Potassse Sulphas (Br.),(K2S04), is found in the Stassfurth mines, in plant ashes, and in solution in mineral waters. It is obtained by the action of sulphuric acid upon potassium chloride, as a by-product in some chemical manufacturing processes. It crystallizes without water, in small, rhombic prisms, of a bitter, salty taste, and is soluble in 10 parts of water at ordinary temperatures. 332. Hydropotassium Sulphate—Monopotassic Sul- phate—Acid Sulphate (KHS04), is formed as a by-product in the manufacture of nitric acid from potassium nitrate; crystallizes in large, rhombic tables, and is very readily soluble in water. At about 200°C. (392°F.) it fuses, loses water, and is converted into the pyrosulphate (K2S207). 333. Sulphites.—Three are known: K2S03, KHS03 and K3S205. Potassium Sulphite—Neutral Potassium Sulphite—Potas- sium Sulphis (U. S.), (lv2S03).—This salt crystallizes in oblique rhombic octahedra, which dissolve readily in water, and have a sulphur- ous odor. When in solution, if exposed to the air, it absorbs oxygen, and is converted into the sulphate. 334. Potassium Acetate—Potassii Acetas (U. S.)—Po- tassse Acetas (Br.), (KC2H302), exists in the juices of plants. It is obtained by neutralizing acetic acid with potassium carbonate or bicar- bonate. It crystallizes in shining needles, deliquescent, and very soluble in water. 335. Oxalates.—Three are known to exist: Potassium Oxalate —Neutral Oxalate (K2C204 + Aq.), formed by saturating oxalic acid with potassium carbonate. Hydropotassium Oxalate—Mono- potassium Oxalate—Binoxalate of Potash (KHC204). Po- tassium Quadroxalate (KHC204. C204H2 + 2Aq.). A mixture of these two salts is known as salt of lemon, or salt of sorrel, and is used for bleaching straw and to remove ink stains. In appearance it closely resembles Epsom salt, and has caused many cases of oxalic acid poisoning, being taken by mistake for that salt. 336. Tartrates.—Potassium Tartrate—Soluble Tartar—Neu- tral Tartrate of Potash—Potassii Tartras (U. S.)—Potassse Tartras (Br.), (K2C4H406), is a white, crystalline powder, very soluble POTASSIUM. 193 water; soluble in 240 parts alcohol. Hydropotassium Tartrate— Creamof Tartar—Potassii Bitartras((J.S.), Potassae Bitartras (KHC4H ,Ofi).—A brown-red, crystalline crust is obtained from the bottom and sides of wine-casks after fermentation has taken place; this ls known in commerce as argol, or crude tartar, and is composed in great part of potassium bitartrate, with tartrate of lime and coloring matter. The argol is boiled with water, or heated in a closed digester by super- heated steam. The latter process renders the calcium tartrate insoluble ?nd separates it almost completely from the cream of tartar, which goes into solution. The solution thus obtained is allowed to cool and crystal- bze ; the crystals are redissolved in hot water, treated with animal charcoal, to remove coloring matters, filtered, and again crystallized. I he product of this process is almost chemically pure acid potassium tartrate. It crystallizes in hard, opaque, rhombic prisms, very sparingly soluble in still less so in alcohol. Its solution is acid to the taste, and to htmus paper. It is largely used in baking, combined with sodium bi- carbonate, the two substances reacting upon each other to form Rochelle salt, with liberation of carbon dioxide. Baking powders are exten- sively used at present, instead of yeast, for bread making. In all of them the action depends upon the decomposition of sodium bicarbonate by some salt having an acid reaction, or by a weak acid. In addition to the bicarbonate, and the starch added to preserve them, many of them contain either tartaric acid, alum, or acid phosphates of calcium, instead of cream of tartar. Some of the reactions that take place to set free the carbon dioxide are the following :— 1. KHC4H406 + NaHCOa = NaKC4H408 + H20 + C02. Potassium bitartrate. Sodium bicarbonate. Sodio-potassi u m tartrate. Wator Carbon dioxide. 2. Al2(S04).K2S04 + 6NaHC0, = K2S04 + 3Na2S04 + Aluminium potassium alum. -Sodium bicarbonate. Potassium sulphate. Sodium sulphate. A1,H60, + 6C02. Aluminium hydra to. Carbon dioxide. 3. CaII4(P04)2 + 2NaHC03 — CaHP04 + NaHP04 Calcium biphosphate. Sodium bicarbonate. 2H20 +2C02. phosphate. phosphate. Hydro-calcium Sodium Water. Carbon dioxide. An artificial powder may be made by intimately mixing two parts cream °i tartar with one of sodium bicarbonate, and adding a little flour or starch. 337. Sodium Potassium Tartrate—Rochelle Salt— Potassii et Sodi Tartras (U. S.), (NaKC4H4Ofi -f- 4Aq.), is prepared by boiling acid potassium tartrate with sodium carbon- ic. It forms large, transparent, prismatic, slightly efflorescent 194 INORGANIC CnEMISTRY crystals, soluble in 21 parts of cold water, saline, and slightly bitter to the taste, and neutral in reaction. 338. Potassium Antimonyl Tartrate — Tartarated Antimony—Tartar Emetic—Antimonii et Potassi Tar- tras (U. S.), (Sb0KC4H406), is prepared by boiling a solution of cream of tartar with antimonious oxide. Its crystals are trans- parent, right rhombic octahedra, efflorescing in the air. It is quite soluble in water, the solution having a nauseating, metallic taste. It is poisonous, and has even caused death when applied to the skin as a local irritant and vesicant. RUBIDIUM and CESIUM. lib = 85.4. Cs = 132.6. 339. These rare metals were discovered in 1860 by Bunsen and Kirchoff, by means of the spectroscope. Both elements were named from the color of their lines in the spectrum (rubidius, dark red, and csesius, sky blue). They occur in small quan- tities, widely distributed, often accompanying potassium. With platinum chloride they form double chlorides (PtCl4.2RbCl). Their compounds have found no use in medicine, as yet. AMMONIUM COMPOUNDS. 340. Ammonium (NH4).—This radical has only a hypo- thetical existence, never having been isolated. But there are many reasons to believe that it does actually exist in combination in the ammonium compounds, and that in these compounds it plays the role of a metal resembling sodium and potassium. The oxide of this radical has not been separated. 341. Ammonium Hydrate (NH4OH) is believed to exist in solution in the ordinary aqua ammonite, although, when the attempt is made to isolate it, decomposition ensues. Aqua Ammonise Fortior (U. S.) has asp. gr. of 0.900, and contains 249.5 grams NH;, per litre. Aqua Ammonise (U. S.) is of sp. gr. 0.960, and contains 93.1 grams NH, per litre. 342. Ammonium Chloride—Ammonium Muriate— Sal-Ammoniac—Ammonii Chloridum (U. S., Br.), (NHt Cl), was formerly obtained by the dry distillation of camels’ dung, and is sometimes found in volcanic regions. At present it is prepared chiefly by saturating the ammonia water from gas works with hydrochloric acid, evaporating the solution to dryness, and subliming the residue in iron vessels. Prepared in this way, it is AMMONIUM COMPOUNDS. 195 a compact, tough, fibrous mass, which dissolves in 2.7 parts cold, and one part boiling water. It crystallizes from its solution in small octahedra or cubes, of a sharp, salty taste, and neutral re- action. When heated, it volatilizes without fusing; at the same time a dissociation into NH3 and HC1 occurs, but on cooling, these products recombine into ammonium chloride. This salt exists in minute quantities in the gastric juice of various animals. The urine, saliva, and tears also contain some ammonium compound, which is said to be the chloride. 343. Ammonium Bromide — Ammonii Bromidum (U. S., Br.), (NH4) Br.), may be prepared by direct combination °f ammonia and hydrobromic acid, or by decomposing ferrous bromide with aqua ammonise. It forms a white, granular powder, or large prisms, which turn yellow on exposure to air, and possess a saline, pungent taste, and neutral reaction. It dissolves in 1.5 parts of water, and volatilizes without decomposition. 344. Ammonium Iodide—Ammonii Iodidum (U. S.), (SHOD, is prepared by the action of hydriodic acid upon ammonia, or by the double decomposition of potassium iodide and ammonium sulphate. It forms cubic crystals, which are deliquescent, and is soluble in 0.60 parts of water. It decom- poses in air, turning yellow and emitting the odor of iodine. 345. Ammonium Sulphide (NH4)S2) is a white, crys- talline solid, formed by mixing dry hydric sulphide and ammonia at a low temperature (—18°C. (about 0°F.). It is usually prepared and used as a yellow solution, by mixing the sulphydrate with ammonium hydrate. It dissolves sulphur and the sulphides of arsenic, tin and antimony, and is used in analysis for this purpose. Ammonium Sulphydrate (NH4SH) is prepared by satu- rating a solution of ammonium hydrate with hydrogen sulphide (sulphuretted hydrogen). It is colorless at first, but becomes yellow, from decomposition, on exposure. It is used in laboratories as a reagent. Acids decompose both these sulphides, setting free sulphur. 346. Ammonium Carbonates.—Three are known: Am- monium Carbonate—Neutral Ammonium Carbonate (AH4)2C03), may be prepared as a crystalline powder, by passing ammonia gas through a concentrated solution of the sesquicar- bonate. Exposed to the air it splits up into ammonia and the acid carbonate, NIIJICO,. Hydro-ammonium Carbonate—Acid Ammonium Car- bonate (NII4HC03), is obtained when a solution of ammonium 196 INORGANIC CHEMISTRY. hydrate or sesquicarbonate is saturated with carbon dioxide. It forms large, rhombic crystals, which are quite soluble in water. At 60°C. (140°F.) it is decomposed into ammonia and carbon dioxide. Ammonium Sesquicarbonate—Sal-Volatile—Ammo- nii Carbonas (U. S.)—Ammoniae Carbonas (Br.), (NH4)4H2)(C03)3, is the commercial carbonate of ammonia, and was formerly prepared by the dry distillation of bones, horns, and other animal substances. It is at present prepared by heating a mixture of ammonium chloride or sulphate with calcium carbonate, and condensing the volatilized product. So prepared, it sublimes as a white, transparent, hard mass, having an ammoniacal odor and an alkaline reaction. On exposure to the air, it gives off ammonia hnd carbon dioxide. The carbon- ates of ammonia are very unstable. 347. Ammonium Nitrate—Ammonii Nitras (U. S.), (NH4)N03), is prepared by neutralizing nitric acid with am- monium hydrate or carbonate. It crystallizes in flexible, six- sided prisms, without water ; dissolves in 0.5 parts water at 18°C. (64.4°F.), and fuses at 150CC. (302°F.). When heated to 210°C. (410°F.), it decomposes, with the formation of nitrous oxide, or laughing gas, and water. (NH4)N03 =* N20 + 2H20. 348. Ammonium Sulphate—Neutral Ammonium Sul- phate—Ammonii Sulphas (U. S.), (NH4)2S04), may be ob- tained by saturating the ammonia water from gas works with sulphuric acid. It forms rhombic crystals, soluble in two parts of cold, and one part of hot water. At 140°C. (284°F.) it fuses, and at higher temperatures it decomposes into ammonia, nitro- gen, water and ammonium sulphite. 349. Ammonium Acetate (NH4)C2H302) is formed when acetic acid is saturated with ammonia or ammonium carbonate. It is seldom seen except in solution in water. The aqueous so- lution is used in medicine, as the Liq. Ammonii Acetatis, or Spirit of Mindererus. Other salts in use are the benzoate, phosphate and valerianate, all white crystalline salts. 350. Action on the Economy.—In large quantities, or by prolonged use, ammonia and its salts are poisonous. Ammonia, if inhaled, acts as a severe irritant upon the air passages, causing dyspnoea, pain, suffocation, and even death. The treatment in cases of poisoning, consists in neutralizing the alkali by dilute CALCIUM. 197 or the vapor of acetic or dilute hydrochloric acids may be Two drachms of a strong solution of ammonium hydrate have proved fatal. METALS OF THE ALKALINE EARTHS. Calcium = 40. Strontium =■ 87.5. Barium = 137.2. 351. The members of this group are called metals of the alka- bne earths because their oxides resemble, on the one hand, the °xides of the alkalies, and, on the other, the real earths (aluminia, etc.). Like the potassium group, their properties and chemical energy increase gradually with their atomic weights. Their J>asic properties also become greater with their atomic weights, ihus, barium decomposes water more energetically, and oxidizes Ufiore readily, than strontium or calcium. Barium hydrate is hkewise the strongest base. It is quite soluble in water. It luses without decomposition upon ignition, and absorbs carbon dioxide rapidly from the air. Calcium hydrate possesses weaker basic properties, is difficultly soluble in water, and, when ignited, breaks up into water and calcium oxide. Strontium stands between barium and calcium. Thus, although these metals resemble the alkaline metals, both in their free state and as hydrates, they essentially differ from them in the insolubility of their carbonates and phosphates, and still more their sulphates. Barium sulphate is insoluble in water and acids. CALCIUM. Ca = 40. 352. Occurrence.—This metal forms one of a class of ele- ments most widely distributed in nature. Its carbonate (lime- stone, marble and chalk), its sulphate (gypsum and alabaster), aiul its phosphate, fluoride, and silicate, are common minerals. Preparation.—Calcium may be obtained from the fused chloride, by electrolysis ; or, by heating calcium iodide with sodium, or calcium chloride with sodium and zinc. Properties.—A light, shining, yellow, ductile metal. It tuses at a red heat, does not sensibly volatilize, and in the air burns with a brilliant reddish-yellow light. It does not undergo decomposition in dry air, but in moist air covers itself with a layer of hydrate. Its specific gravity is 1.984. . 353. Calcium Oxide—Lime—Calx (U. S., Br.), (CaO.), Is obtained pure by igniting the carbonate or nitrate. On a large scale, it is prepared commercially by burning the natural carbonate (limestoneor marble) in rude stone furnaces, called lime 198 INORGANIC CHEMISTRY. kilus. It is a grayish-white, amorphous solid, alkaline and caustic; sp. gr. 2. 3; it does not fuse at any temperature at our command. When the oxy-hydrogen flame is thrown upon it, it becomes incandescent, and emits an extremely intense white light. (Cal- cium, or Drummond light.) It combines energetically with water to form the hydrate, the process known as slacking, and is at- tended with the evolution of much heat. Exposed to the air it attracts moisture and becomes air-slacked. 354. Calcium Hydrate—Slacked Lime—Calcis Hydras (Br.), (Ca(OH)2, is a dry, white powder, odorless, and alkaline in reaction. It is slightly soluble in cold and less so in hot water. Exposed to the air it absorbs carbon dioxide and forms carbon- ate. Ordinary mortar is a mixture of slacked lime, water and quartz sand. The hardening of mortar depends upon three causes: 1st. The natural evaporation of the water. 2d. The absorption of carbon dioxide from the air, and the formation of calcium carbonate. 3d. The action of the hydrate upon the silicic acid of the sand, producing calcium silicate. This last reaction takes place slowly; hence the hardness of old mortars. Hydraulic mortar, or cement, contains calcium oxide, alumi- nium silicate and quartz powder; its hardening depends principally upon the formation of calcium and aluminium sili- cates. 355. Lime Water—Liquor Calcis (U. S., Br.), is a clear solution of the calcium hydrate in water. Cane-sugar increases the solubility of calcium hydrate in water, with which it forms a saccharate. The British Liquor calcis saccharatus is a solution of calcium hydrate in a strong solution of cane-sugar. When lime-water contains an excess of the hydrate, rendering it turbid, it is called milk of lime. 356. Calcium Chloride—Calcii Chloridum (U. S., Br.), (CaCl2), is prepared by the action of hydrochloric acid upon marble. It crystallizes with 6 molecules of H20, in large, six- sided prisms, which are bitter, deliquescent, and very soluble in water. _ If heated, it melts in its water of crystallization with some loss of water. Above 200°C. (392°F), it becomes anhy- drous. The dry salt is a white, porous mass, which fuses at a red heat and solidifies to a crystalline mass, which rapidly absorbs water, and is used as a drying agent for gases and liquids. Calcium iodide and bromide are very similar to the chloride. 357. Chloride of Lime—Bleaching Powder—Calx Chlorinata (U. S.), Calx Chlorata (Br.), is a mixture of calcium chloride (CaCl2), and calcium hypochlorite (Ca(C10)2), CALCIUM. 199 V’ith some water. The hypochlorite is the active principle. It is prepared by passing chlorine over slacked lime. From the analogous action of chlorine upon sodium or potassium hydrate, we may express the reaction in the case of calcium hydrate by the following equation :— According to this equation, the completely chlorinated chloride of lime »ust, contain 48.9 per cent of chlorine, which is never the case, as a Portion of the calcium hydrate always remains unchanged. rl he exact constitution of chloride of lime is in doubt; but from more recent obser- vations, it is believed by some that the active constituent of chloride of v • /0C1’ llrue i3 a basic calcium hypochlorite and the following reaction takes place when chlorine acts upon calcium hydrate:— 3Ca(OH)2 + 2C12 = 2Ca02HCl + CaCl2 + 2H20. Calculating from this equation, completely saturated chloride of lime 0n'y contains 39 per cent, chlorine, which is found to be actually the case. Chloride of Lime is a grayish-white, porous powder, hav- ing a bitter, acrid taste, and a chlorine-like odor; it is alkaline in reaction, soluble in cold and decomposed by boiling water. It slowly decomposes in the air, the carbon dioxide liberating hypo- chlorous acid ; this decomposition is hastened by sunlight and heat. Dilute mineral acids decompose it very rapidly, with libera- tion of chlorine. The application of chloride of lime for bleach- ]ng and disinfecting purposes, depends upon this production of free chlorine. The amount that will be set free by acids, is called the active chlorine, which in good chloride of lime should be at least 25 per cent. 358. Calcium Sulphate (CaS04) occurs very abundantly nature as gypsum, in right rhombic prisms, combined with two molecules of water. The anhydrous salt forms the mineral anhydrite. It is very sparingly soluble in water. One part dissolves at ordinary temperatures in 400 parts H20. Ground gypsum is used in the arts under the name of terra alba. When heated to 200°C. (392°F.), it parts with its water, becoming con- verted into an opaque white mass, which, when ground, is called Plaster-of-Paris. This powder, mixed with water, takes up two molecules and hardens into a stone-like solid. Upon this property depends the usefulness of plaster for making moulds, hgures, and immovable surgical dressings. 359. Tricalcium Phosphate—Tribasic, or Neutral, or Bone Phosphate—Calcis Phosphas Precipitata (U. S.), Calcis Phosphas (Br.), (Ca3(P04)2), is found in rocks and 2Ca(OH)2 + 2C12 = Ca(OCl)2 + CaCl2 + 2H20. 200 INORGANIC CHEMISTRY. soils, in guano, in all plants, and in every tissue and fluid of animal bodies. It may be prepared pure by dissolving bone ash in hydrochloric acid, filtering, and precipitating with ammonium hydrate; or, by a double decomposition between calcium chloride and an alka- line phosphate. It is a gelatinous mass when first precipitated; but, after drying, a white, amorphous powder. It is insoluble in water, but readily soluble in dilute acids, even acetic; also in water charged with carbon dioxide. An impure tricalcium phosphate, prepared by burning bones, is known as bone-ash. 360. Dicalcium Phosphate (Ca2HP04 -(- 2H20) separates as an amorphous insoluble precipitate, when disodium phosphate is added to a solution of calcium chloride mixed with some acetic acid. 361. Monocalcium Phosphate—Acid Calcium Phos- phate—Superphosphate of Lime (Ca(H2P04)2), is found in brain tissue and in acid animal fluids. It is produced by the action of sulphuric or hydrochloric acid upon the first two phos- phates, and is manufactured as a fertilizer, mixed with calcium sulphate, by decomposing bones with sulphuric acid. At a tem- perature of 200°C. (392°F.), it splits up into pyrophosphate, metaphosphoric acid and water. When this mixture is ignited with charcoal, the metaphosphoric acid is reduced to phosphorus. 362. Calcium Carbonate—Calcis Carbonas (U. S., Br.), (CaCO.,), is of exceedingly wide distribution in nature. It exists sometimes in enormous deposits, as limestone, marble, chalk, Iceland spar, and as the mineral basis of the corals, shells of the Crustacea, mollusks, etc. Chalk is a comparatively pure, amor- phous calcium carbonate, made up of microscopic shells. The precipitated chalk of the Pharmacopoeia is prepared by precipi- tating calcium chloride with sodium carbonate, filtering off and washing with water. Prepared chalk—creta preparata (U. S., Br.), is a native chalk, purified by elutriation, which consists in grinding the chalk in water, allowing the mixture to subside, decanting the upper portion, and collecting and drying the finer particles. Calcium carbonate is nearly insoluble in pure water, but dis- solves readily in water containing carbon dioxide ; hence, we find it dissolved in nearly all natural waters, as an acid or bicarbonate (CaH2(COj)2), giving rise to temporary hardness. Boiling, 2Ca (H2P04)2 = Ca2P207 + 2HP0S + 3H20. STRONTIUM. 201 agitation, or free exposure to the air may decompose this salt, and deposit the ordinary calcium carbonate. Upon this depends the formation of lime scales, stalactites, boiler incrustations, and similar deposits. 363. Calcium Oxalate (CaC204) is found in the juice of some plants and in the urine. It may be obtained, as a fine, white, crystalline powder, by adding any soluble oxalate to a soluble calcium salt in neutral or alkaline solution. It is insoluble in water and acetic acid, but soluble in the mineral acids. In many diseased conditions which produce deficient oxidation or ex- cessive production of acids, (lung disease and acid dyspepsia), it occurs in considerable quantities in the urine, and gives rise to oxaluria, or the oxalic acid diathesis. This salt frequently forms calculi, which present irregular projections and have received the name of mulberry calculi. Excessive saccharine diet, or ex- cessive consumption of certain vegetables, as tomatoes, rhubarb, etc., increases the production of calcium oxalate. 364. Physiological Effects and Uses.—The calcium salts play an important part in the animal economy. The phos- phates are found in every tissue and fluid of the body, but most abundant in the bones and teeth; the former containing from 55 to 59 per cent., and the latter, including the carbonate, 72 per cent. As the salts of lime are insoluble in alkaline fluids, various theories have been put forward to explain its state in the blood and other alkaline fluids. It seems certain that the calcium of blood serum does not exist as phosphate, but as some soluble salt, or albu- min compound, soluble in alkaline fluids. The calcium phosphate of the urine remains in solution as long as that fluid is acid, but separates as an amorphous or crystalline sediment as soon as it undergoes alkaline fermentation. Alkaline urine is always turbid. When taken internally, the calcium salts produce effects similar to those of sodium and potassium, but milder. They have a mild astringent effect. STRONTIUM. 365. Strontium is rather sparingly found in nature. The principal minerals are strontianite (SrCOf) and celestite (SrS04). It is a brass-yellow, lustrous metal, which resembles calcium in its properties, as also do its compounds. This element ex- hibits most of the properties of calcium and barium. Its com- pounds impart a red tinge to the flame,-and for this reason the nitrate is used as a constituent of red fires. The solubility of its Sr = 87.5. 202 INORGANIC CHEMISTRY. sulphate stands between that of the calcium and barium sulphates. It has been used in medicine as an alterative. Its salts are poi- sonous only in large quantities. BARIUM. Ba = 137.2. The element itself is not of interest to the medical student. 366. Barium Oxide—Baryta (BaO), is obtained by cal- cining the nitrate. It is a grayish-white, caustic powder, fusible in the oxyhydrogen flame. It unites with water, with the evolu- tion of much heat, to form the hydrate BaH202; this dissolved in water forms baryta water. There is a barium peroxide known (Ba02), which is decom- posed by dilute acids, with the production of hydrogen peroxide. 367. Barium Chloride—Barii Chloridum (U. S.), (BaCl2 + 2Aq.), is prepared by the action of hydrochloric acid upon the native sulphide or carbonate. It is used as a reagent for soluble sulphates, giving a white precipitate, insoluble in acids or water. It has been used in medicine as an alterative and anthelmintic. 368. Barium Nitrate (BaN03) forms anhydrous octahedra of the regular system, soluble in water, and used as a constituent of pale green theatre fires. 369. Barium Sulphate (BaS04), Heavy Spar, or Barite, occurs in nature in . rhombic prisms and amorphous; sp. gr. 4.6. It is obtained by the action of sulphuric acid upon barium salts, as a white amorphous powder, nearly insoluble in acids and water. It is used as an adulterant of white paint, Paris green, and a variety of other commercial products. 370. Barium Carbonate (BaC03) also occurs native as witherite. It precipitates from solutions of barium salts, as a white, amorphous powder, when they are acted upon by soluble carbonates. 371. Physiological Effect of Barium Salts. All the soluble compounds of barium, as well as those that are converted into soluble compounds in the stomach, are poisonous. When- ever a poisonous dose has been taken, the patient should take some soluble sulphate (as Epsom or Glauber’s salt), followed by an emetic. The symptoms of poisoning are pain in stomach, prostration, dilated pupils, loss of voice, sight or hearing, excessive micturition, and other very prominent nervous symptoms. Post- mortem, inflammation and great friability of stomach, in most cases, and invariably great inflammation of the rectum are found. MAGNESIUM. 203 METALS OF THE MAGNESIUM GROUP Magnesium = 24. Zinc = 65.2. Cadmium = 112. 372. These metals form but one oxide, with a corresponding basic hydrate, and a series of salts in which the atoms possess a quantivalence of two. According to some authorities, the rare element beryllium is included in the group. MAGNESIUM. 373. Occurrence. A metal, found abundantly in nature, usually accompanying calcium. Dolomite, an isomorphous mixture of calcium and magnesium carbonates, forms the so-called magnesium limestone. Asbestos, serpentine, meerschaum, talc or soapstone, and hornblende are native silicates. Nearly all natural waters contain some of the soluble salts of magnesium, which impart hardness to them. 374. Preparation. It may be obtained either by electro- lysis of the chloride, or by heating the same compound with sodium. In the arts it is prepared by fusing the double chloride of sodium and magnesium with metallic sodium. Mg = 24. MgCl2NaCl + 2Na = 3NaCl + Mg. It is then purified by distillation in an atmosphere of hydro- gen. 375. Properties*—Magnesium is a brilliant white metal, of a SP- gr- of 1.75; very tenacious and ductile. It fuses at a dull red heat, and at a bright red heat it distills. It oxidizes but slightly in the air, at ordinary temperatures, but when heated, it burns with an intensely brilliant bluish-white light, owing to the incan- descence of the non-volatile magnesium oxide. The flame of burning magnesium is rich in chemically active or actinic rays; hence, it is much employed for photographing in dark caves and subterraneous chambers. It combines directly with chlorine, sulphur, phosphorus, arsenic and nitrogen. Soluble in dilute acids, but not in alkalies. It is slowly oxidized by boiling water. 376. Magnesium Oxide—Calcined Magnesia—Mag- nesia (U. S., Br.), (MgO), is formed by the combustion of the metal, or by the ignition of the carbonate, hydrate, or nitrate. It is a very light, white powder, without odor or taste, and has a feeble alkaline reaction. It is soluble in dilute acids. A compact variety, prepared by heating the nitrate or chloride to bright redness, and no higher, exhibits remarkable hydraulic properties. If 204 INORGANIC CHEMISTRY. moistened with water to a paste, it quickly hardens to a compact white solid, of great hardness and durability. If it be mixed with an equal part of marble dust or chalk and moistened, it may be moulded into any desired shape, and on being placed in water, it “sets” into an extremely hard mass. It has been used as a filling for decayed teeth. 377. Magnesium Hydrate — Hydrated Magnesia Mg(HO)2, is formed from any soluble magnesium salt by precipitating with sodium or potassium hydrate. It is almost insoluble in water and alkalies, but soluble in ammonium salts with the formation of double salts. A mixture holding it in suspension in water, known as milk of magnesia, is used in medicine as a laxative and an antidote for acid poisons. 378. Magnesium Chloride (MgCl2) exists in small quanti- ties in many mineral springs. It may be obtained by dissolving the carbonate or oxide in hydrochloric acid. It forms deli- quescent crystals with 6 molecules of H20, isomorphous with calcium chloride. The anhydrous chloride is one of the most deliquescent substances known. 379. Magnesium Sulphate — Epsom Salt — Seidlitz Salt—Magnesii Sulphas (U. S.)—Magnesiae Sulphas (Br.), (MgSOJ, is found in solution in sea waters and in many mineral springs, especially those belonging to the class of bitter waters. It is prepared by the action of sulphuric acid upon magnesium carbonate. At ordinary temperatures it crystallizes with 7 mole- cules of H20, in four-sided, rhombic prisms, very readily soluble in water. When heated, it fuses and parts with its water of crys- tallization up to 150°C. (30'2°F.), when it has lost all but one molecule; this it finally parts with when heated to 200°C. (392°F.) One molecule of water, therefore, is more closely combined than the rest. This is known as the Water of Con- stitution. 380. Magnesium Phosphates.—These resemble the cal- cium phosphates, which they generally accompany in the animal body, though usually existing in smaller quantity. Magnesium also forms double phosphates, one of which, the Ammonio- magnesium phosphate, or triple-phosphate (MgNH4 P04 + 6H20), is precipitated when an excess of an alkaline phosphate and of ammonia is added to a solution containing magnesium. When the urine becomes ammoniacal from the decomposition of urea, this salt is precipitated, as urine always contains alkaline phosphates and magnesium salts. Being practi- cally insoluble, especially iri the presence of excess of phosphates ZINC. 205 and of ammonia, it is usually deposited from the urine as a sedi- ment, in the shape of modified right rhombic prisms, which, under the microscope, resemble the shape of a coffin lid. This some- times takes place in the bladder, and if some body is present that will act as a nucleus, the so-called fusible calculus may form. 381. Magnesium Carbonate — Neutral Carbonate (MgCOs), occurs in nature as magnesite, and, combined with calcium carbonate, as dolomite. On adding an alkaline car- bonate to an aqueous solution of a magnesium salt, magnesium carbonate is not produced, as most other carbonates would be under similar circumstances, but some carbon dioxide escapes, and a white precipitate falls, which is a mixture of magnesium carbonate and hydrate, or magnesia alba. 382. Tetramagnesium Carbonate—Magnesia Alba— Magnesii Carbonas (U. S.), Magnesiae Carbonas (Br.), (3(MgC03).MgH202-f 3H20), occurs in commerce in light white cubes, composed of an amorphous or partly crystalline powder. It is prepared by precipitating a solution of magnesium sulphate with one of sodium carbonate. A hot concentrated solution should be used, and the liquid boiled after precipitation. This compound varies in constitution according to the length of time that the boiling has continued, and the presence or absence of excess of sodium carbonate. It is very slightly soluble in water, but quite soluble in solutions of ammonium chloride. ZINC. Zn = 65.2. 383. Occurrence. The native compounds of the heavy metals are termed ores. The most common zinc ores are Smith- sonite (ZnC03.), Calamine, (Silicate) and Sphalerite or Blende (ZnS). These, like most ores, have a high specific gravity, and usually are found in veins in the older crystalline rocks. 384. Preparation. To obtain the metal, one of its ores, usually the carbonate or sulphide, is converted into an oxide by roasting, heating to a high temperature in the air. This oxide is then mixed with carbon and ignited in cylindrical earthenware tubes, reducing the oxide thus: ZnO + C = Zn + CO. The free zinc is then distilled off. 385. Properties. A bluish-white metal, roughly crystalline or granular; its specific gravity is 6.862, if cast; 7.215, if rolled. 206 INORGANIC CHEMISTRY. It is brittle at ordinary temperatures and can be pulverized ; at 100°C. (212°F.) to 150°C. (302°F.), it is malleable and ductile, and may be rolled into thin sheets. At 200°C. (392°F.), it again becomes brittle. It fuses at 412°C. (773°F.), and distills at 1040°C. (1872°F.). In moist air it becomes coated with a thin layer of basic carbonate. When heated in the air, it burns with a very intense bluish-white light, with the formation of oxide. It dissolves readily in dilute acids with evolution of hydrogen. Concentrated sulphuric acid does not dissolve zinc. It is soluble in sodium, potassium and ammonium hydrates. On account of the slight action of the air upon it, zinc meets with extensive application in architecture, and for galvanizing or coating iron. 386. Zinc Oxide—Zinci Oxidum (U. S., Br.), (ZnO), may be prepared by igniting the precipitated basic carbonate, or by burning the metal in a current of air. When obtained in the former way, it forms a soft, white, tasteless and odorless powder. When produced by burning the metal, it occurs as a white, voluminous, flocculent mass, formerly called flores zinci or lana philosophica. It neither fuses, volatilizes, nor decom- poses by heat, and is insoluble in neutral solvents. It is used in the arts as a white pigment, and is not darkened by hydrogen sulphide, as white lead is. 387. Zinc Hydrate (Zn(OH)2) is formed, as a white amor- phous powder, by precipitating an aqueous solution of a zinc salt, by alkalies. It is soluble in alkaline hydrates and in solutions of ammonium salts. When heated, it decomposes into zinc oxide and water. 388. Zinc Chloride—Butter of Zinc—Zinci Chloridum (U. S., Br.), (ZnCl2), is obtained by heating zinc in a stream of chlorine, by dissolving zinc in hydrochloric acid, and by the distillation of zinc sulphate with calcium chloride. It forms a soft white mass, which is very deliquescent; is fusible and volatile. It is extremely soluble in water, freely so in alcohol. The solution has a burning metallic taste, destroying animal and vegetable tissues, and possessing strong dehydrating properties. It forms a series of double salts. The double chloride of zinc and ammonium is sometimes used in soldering, to dissolve metallic oxides from the surface of metals to be soldered. 389. Zinc Sulphate—White Vitriol—Zinci Sulphas (U. S., Br.), (ZnS04), is formed by dissolving zinc, or its oxide, sulphide, or carbonate, in sulphuric acid. At temperatures below 30°C. (86°F.), it crystallizes with 7 Aq.; at 30°C, (86°F), with 6 Aq.; between 40°C. (104°F) and 50° (122°F), with 5 CADMIUM. 207 Aq. The most common salt is that with 7 Aq., which occurs in rhombic crystals resembling magnesium sulphate; and is freely soluble in water. It is used in medicine as an emetic and astringent. 390. Toxicology. The compounds of zinc that are soluble in the digestive fluids are all irritant poisons. Solutions of the chloride (used by tinsmiths, in embalming, and as a disinfectant in Burnett’s fluid,) are also very corrosive. The antidotes are alkaline carbonates, soap, albumen and mucilage. Solutions containing sodium chloride or organic acids act as solvents upon metallic zinc; consequently, symptoms of poisoning, more or less marked, are apt to follow eating of acid fruits that have been kept in vessels of galvanized iron. On this account, specimens intended for analysis in cases of supposed poisoning should never be placed in jars closed by zinc caps. 391. Tests. With alkaline hydrates and carbonates, solutions of zinc give a white precipitate, soluble in excess of the reagent; with ammonium sulphydrate or sulphydric acid in neutral or alkaline solutions, a white sulphide; with potas- sium ferrocyanide, a yellowish-white precipitate, insoluble in dilute hydrochloric acid. CADMIUM. Cd =*112. 392. Occurrence, Preparation, Properties, etc.—A comparatively rare metal, often accompanying zinc in its ores. Being more volatile than its associate, it accumulates during the first stages of the process of distilling zinc from its ores. It is a soft, white, tenacious metal, of specific gravity 8.6. It alters but little in the air at ordinary temperatures. Heated, it burns with formation of the oxide as a brown smoke. It dissolves with difficulty in sulphuric and hydrochloric acids, but readily in nitric acid. 393. Cadmium Compounds.—These are not very numer- ous or important. As the element is bivalent, they all have the general formula, CdR2. The principal ones are : cadmium hydrate (Cd(OH)2), cadmium oxide (CdO), cadmium chloride (CdCl2), cadmium iodide (Cdl2), cadmium sulphate (CdS04) and cadmium sulphide (CdS). The latter is found native in the mineral Greenockite. 208 INORGANIC CHEMISTRY. Chromium = 52.4. Manganese — 54.8. Iron = 56. IRON GROUP. 394. The elements of this group form two series of compounds, due to a peculiar variation of the quantivalence. In one series, a single atom enters into combinations as a dyad, as in Fe"Cl2; in the other, two atoms combine to form a hexad group, as in (Fe2)VIClB. In this hexad condition they form acid radicals with oxygen, and form chromates, manganates and ferrates. CHROMIUM. Cr = 52.4. 395. Occurrence, Preparation and Properties.—This metal most commonly occurs in chromite, or chrome iron ore, a ferroso-chromic oxide; also, rarely, as lead chromate. It may be isolated with difficulty from its oxide by reducing with char- coal ; or from the chloride by reducing with zinc. It is a hard, glistening, steel-gray metal, magnetic at low temperatures; sp. gr. 6.8; oxidizes only at a red heat, and is soluble in hydro- chloric acid and strong alkalies. 396. Chromic Anhydride—Chromic Trioxide —This is sometimes improperly galled chromic acid. It is prepared by adding one and one-half parts strong sulphuric acid to one part of concentrated solution of potassium dichrom- ate. When the solution cools, splendid saffron-colored needles of the trioxide crystallize out, which may be dried on a porous tile. It is a powerful oxidant, igniting alcohol if the latter be poured upon it. It is used in medicine as a caustic, forming a superficial eschar. 397. Chromic Oxide—Chromium Sesquioxide—Green Oxide (Cr2’03),is obtained by calcining a mixture of starch and potassium dichromate. Thus prepared it is a green powder, insoluble in water, acids or alkalies, and fusible with difficulty. When fused with alkaline hydrates or nitrates, it forms chromates of these metals. This oxide may play either a positive or negative role, depend- ing upon the oxide with which it unites. For example, with the strongly negative sulphuric oxide, it forms chromium sulphate (Cr2(S04)3) ; while with calcium or magnesium oxide, calcium or magnesium chromites (CaCr204 or MgCr204) are obtained. The best known of these compounds is (FeCr204) ferrous chromite, or native chrome iron. CHROMIUM. 209 398. Chromous Oxide (Cr"0).—This exists only as a hydrate, produced by precipitating chromous chloride by potas- sium hydrate. It acts as a basic oxide, yielding chromous salts. 399. Chromic Acid (H2Cr04).—This cannot be isolated, but by solution of chromium trioxide in water, an acid liquid is obtained containing chromic acid. This acid decomposes on evaporation. The best known of the salts of this acid are potassium chrom- ate and dichromate (K2Cr04 and K2Cr207). The last of these possesses the properties of the trioxide, but in a milder degree. It is sometimes used as an escharotic, but much more frequently as an oxidizing agent, mixed with sulphuric acid. None of the other preparations of chromium are used in medicine. Inter- nally, in large doses, it acts as an irritant poison. Antidotes— mild alkalies, demulcents. A form of chronic poisoning some- times affects workmen who handle it. 400. Chlorides.—Two chlorides are knowm : Chromous Chloride (CrCl2), a white, crystalline solid, dissolving in water to form a blue solution ; and chromic chloride (Cr2Cl6), occur- ring in large red crystals, insoluble in water, unless a trace of the chromous chloride be present, when it dissolves readily. If it be subjected to a prolonged boiling, it finally dissolves, forming a green solution containing a hydrate. An oxychloride is also known. 401. Chromic Sulphate (Cr2(S04)3) is obtained by dis- solving chromic oxide in sulphuric acid; upon slowly evaporat- ing, it crystallizes with twelve molecules of water. Chromium salts form two series, the one green and the other violet. The alkaline hydrates throw down a bluish-green hydrate from the green salts, and a violet from the violet. Chromium sulphate exists as a violet crystalline solid, and as a green amorphous solid. With the alkaline sulphates, chromium sulphate forms double salts—the chromium alums. (See Alums.) 402. Potassium Chromate (K2Cr04) is obtained by adding a solution of potassium hydrate to one of potassium dichromate. It forms large, yellow, rhombic crystals, isomor- phous with potassium sulphate (K2S04). 403. Potassium Dichromate (K2Cr207), commercially known as the red chromate of potash and often called the acid potassium chromate, is obtained by igniting pulverized chromite (Cr203Fe0) with potassium carbonate and nitrate, forming potassium chromate and ferric oxide. The potassium 210 INORGANIC CHEMISTRY. chromate is dissolved out with water and nitric or acetic acid added to the solution, from which potassium bichromate crystal- lizes. It forms large, red prisms, soluble at ordinary tempera- tures in ten parts of water. When it is warmed with sulphuric acid, oxygen escapes, and chromic acid and potassium chrome alum are produced. This mixture is employed in laboratories for oxidizing purposes. 404. Toxicology.—The chromates, especially potassium dichromate, are irritant poisons. They are also liable to pro- duce a form of chronic poisoning in workmen handling them, characterized by ulceration of the septum of the nose, and of the skin. The most prominent symptoms in acute poisoning are vomiting, epigastric pain, cramps, excessive thirst and collapse. The treatment consists in the use of emetics, followed by mag- nesium carbonate in milk. MANGANESE. 405. Occurrence. Manganese is found widely distributed in nature. It occurs native in meteorites. Its most common ores are pyrolusite (Mn02), hausmanite (Mns04), braunite (Mn2Os), manganite (Mn203H20), and rhodochrosite (MnCOa). 406. Preparation and Properties. It is obtained in the metallic condition by heating its oxides with charcoal, similar to the smelting of iron. A grayish-white, brittle metal, very hard, and fusing with great difficulty ; sp. gr. 7.2. Like the elements iron and chromium, it forms three series of compounds; the manganous (MnR2), manganic (Mn2R4), and the derivatives of manganic acid, called manganates. 407. Manganous Compounds. In these the metal is dia- tomic. These derivatives are the most stable and constitute the most common of the manganese salts. They resemble the ous salts of iron and chromium, with which they are isomor- phous. Manganous oxide (MnO) results from ignition of the carbonate with exclusion of air. It is a greenish, amorphous powder, readily oxidizing in the air to Mn304. Manganous hydrate (Mn(OH4)2) is formed by adding alkaline hydrates to manganous solutions, as a reddish-white precipitate, which, ex- posed to the air, oxidizes to manganic hydrate, and turns brown in color. 408. Manganous Salts.—Manganous Chloride (MnCl2) occurs in rose-colored tabular crystals, which decompose on Mn = 55. MANGANESE. 211 drying, with separation of hydrochloric acid. Manganous Sulphate (MnS04) crystallizes at ordinary temperatures with 5H20. With the alkaline sulphates it forms double salts; e. g., MnS04.K2S04 -f 5H20. Manganous Carbonate (MnC03) is precipitated from manganous solutions by alkaline carbonates as a white powder, turning brown on exposure. Manganous Sulphide (MnS) occurs in nature as alabandite, or manganese blende, and is precipitated from manganous solutions by alkaline sulphides as a flesh-colored hydrate (MnS -f- H20). In the air it also becomes brown. 409. Manganic Compounds.—These are isomorphous with, and very closely resemble the ferric, chromic and aluminic compounds. They are not so stable, however, being easily re- duced to the manganous state. In them manganese is a tetrad. 410. Manganese Dioxide — Manganic Peroxide — Black Oxide of Manganese (Mn02), occurs native as the mineral pyrolusite, the principal ore of manganese, in steel- gray or brownish, imperfectly crystallized masses. When gently heated, it yields oxygen; at a red heat, it yields more oxygen and forms manganous-manganic oxide. 3Mn02 = Mn304 + 20. It gives off oxygen when heated with sulphuric acid, and forms manganous sulphate. With hydrochloric acid, it yields mangan- ous chloride, water and chlorine. Mn02 + 4HC1 = MnCl2 + 2H20 + Cla. In cold hydrochloric acid, it dissolves without setting chlorine free, as MnCl4 is probably formed, which, upon heating, breaks up into MnCl2 and Cl2. From this it would appear that, in the dioxide, manganese is a tetrad. Manganic Oxide (Mn203) is a black powder, produced by igniting the manganese oxides in a current of oxygen. Manganic Hydrate (Mn2OH6) is precipitated from man- ganic solutions by ammonium hydrate as a flesh-colored precipi- tate, rapidly turning brown. Manganous-manganic Oxide (Mn304 = Mn0,Mn203). ~ This is formed by the ignition of all the oxides in the air ; it is isomorphous with Magnetite (Fe304). Manganic Sulphate (Mn2(S04)3) is produced by the action of sulphuric acid upon manganic hydrate. 411. Manganates and Permanganates.—The derivatives of manganic acid (H2Mn04 = Mn02(0H)2) are analogous to 212 INORGANIC CHEMISTRY. those of ferric (H2Fe04), chromic (H2Cr04), and sulphuric acid (H2S04). In these derivatives, manganese is a hexad. The manganates are of little permanency and little used. Potassium Manganate (K2Mn04) is a rare substance, isomorphous with potassium sulphate or chromate, and is very readily converted into potassium permanganate. 412. Potassium Permanganate (KMii04) is precipitated from solutions of potassium manganate by acids, in dark-red, rhombic prisms, isomorphous with potassium chlorate. This salt has active oxidizing properties, and is very largely used for oxidizing and destroying organic substances. It also converts ferrous into ferric salts, and is used for the quantitative estima- tion of ferrous salts. IRON. Fe = 56. 413. Occurrence. —This metal, which is of so great practical importance, is distributed very widely in nature. It occurs native upon the earth’s surface only as meteorites. The ores from which iron is obtained are numerous ; the most important are: magnetite (Fes04), haematite (Fe203), limo- nite (ferric hydrate) and siderite (FeCOs). These are almost the only ores used for the manufacture of iron ; the sulphur ores are not adapted for this purpose. 414. Preparation.—In some cases the ore is first roasted, to get rid of water, carbon dioxide, sulphur, etc. The next step consists in the extraction of the iron from the ores, in which it exists as oxide ; this is accomplished by reduction with carbon, at a glowing heat. This reduction is effected in a blast furnace, of which the interior has the shape of a double cone. It is about fifty or sixty feet high by fifteen feet wide at its widest part, is built of the most infusible fire brick, and inclosed in solid masonry. It is filled at the top w7ith alternate layers of coal, broken ore (either native or previously roasted), and fluxes in the form of limestone or silicates. These fluxes facilitate the melting together of the reduced iron, and furnish a liquid slag. The air necessary for combustion, usually heated to a high temperature beforehand, is forced into the bottom of the furnace, through pipes, by blowers or fans. The metal is drawn off at the bottom. In the lower part of the furnace, carbon dioxide is produced from the oxygen of the air and the coal; and higher up, carbon monoxide is produced, which acts upon the oxide of iron, reducing it to the metallic state. As the reduced IRON 213 iron sinks, it comes into contact with the coal, takes up a small quantity of carbon, and forms cast-iron, which, on further sink- ing, fuses, and is drawn off into moulds made in sand, to form pig iron. The earthy impurities of the ores remaining in the furnace unite with the fluxes, fuse in the intense heat, and are drawn off as slag. The pig iron is then subjected to the puddling process, by which it is more completely freed from carbon and slag, and wrought iron results. This process is usually carried on in reverberatory furnaces with a free supply of air, while the molten mass is being thoroughly stirred. The greater part of the carbon is in this way burned into carbon monoxide, and the silicon, sulphur and phosphorus oxidized. Steel was formerly prepared from wrought iron only, by cementation, or heating wrought iron in boxes packed in leather shavings or with charcoal. At present it is chiefly prepared directly from cast or pig iron by the method in- vented by Bessemer in 1850. This process consists in blowing air, under high pressure, into a mass of molten cast-iron, until the carbon has been consumed, when spiegeleisen, containing a known quantity of carbon, is added, to give the proper amount of carbon. Pure iron is obtained by heating ferric oxide in a current of hydrogen ; this is the ferrum redactum (U. 8., Br.). 415. Properties.—Pure iron is soft, fuses at about 1600°C. (2912°F.), and has a specific gravity of 7.25 to 7.9. Iron is not affected by dry air at ordinary temperatures; in moist air, it covers itself with a thin layer of ferric hydrate, known as rust. Heated strongly in the air, it becomes coated with a layer of ferrous-ferric oxide (Fe304), which is readily loosened, forming the blacksmith’s scales; at a red heat, it decomposes water, with the formation of ferrous-ferric oxide, and the liberation of hydrogen. In oxygen it burns with an intense, scintillating light. If brought into contact with a magnet, iron becomes magnetic. Tempered steel is the only form, however, that retains the niagnetism. Iron unites directly with chlorine, bromine, iodine, sulphur, and the members of the phosphorus group, except nitrogen. It dissolves readily in hydrochloric and sulphuric acids, with evo- lution of hydrogen. In dilute nitric acid, it dissolves with separation of nitric oxide. Concentrated nitric acid, however, renders it passive, when it is no longer attacked by the dilute 3Fe + 4H20 == Fe304 + 4H2. 214 INORGANIC CHEMISTRY. acid, until the passive condition is destroyed by contact with silver, platinum or copper, or by heating to 40° C. (104° F.). 416. Ferrous Compounds.—These are formed by dis- solving iron in an acid, or by the reduction of ferric salts. They are usually of a green color in the hydrous state ; exposed to the air, they oxidize to ferric salts. Fe2Cl -f- Zn •= (FeCl2)2 + ZnCl2. 2FeO + 0 = Fe203. 417. Ferrous Chloride (FeCl2) is formed when iron is dissolved in hydrochloric acid. It crystallizes in green, mono- clinic prisms, containing four molecules of water. Exposed to the air, they deliquesce and oxidize, forming ferric chloride and an oxychloride. The anhydrous chloride is formed by passing hydrochloric acid gas over iron that is heated to redness, as a volatile, yellowish-white, very soluble solid. 418. Ferrous Iodide—Ferri Iodidum (Br.), (Fel2), is obtained in solution by adding an excess of iron to iodine sus- pended in warm water until the solution is pale green. 419. Ferrous Oxide (FeO) is a black powder, produced by the reduction of ferric oxide by carbon. It easily oxidizes again. Ferrous Hydrate (Fe(OH)2) is precipitated from ferrous solutions by alkali hydrates as a white powder. It also oxidizes readily, becoming green, and then brown. 420. Ferrous Sulphate — Protosulphate of Iron— Green Vitriol — Copperas — Ferri Sulphas (U. S., Br.), (FeS047H20), is obtained pure by dissolving iron in dilute sulphu- ric acid. For commercial use it is obtained from pyrites (FeS2) by oxidation, arid as a by-product in other processes. It forms oblique rhombic prisms. At a red heat, it decomposes into ferric oxide, and sulphur di- and trioxides. On this property is based the production of fuming, or Nordhausen sulphuric acid. Green vitriol has an extended use in the arts. Among other uses, it is employed in the manufacture of ink, and as a mordaunt in dyeing. Ammonio-ferrous Sulphate (Fe(NH4)2.(S04)2.6H20) is also known. It is more stable than ferrous sulphate. 421. Ferrous Carbonate (FeC03) exists in the mineral, siderite. It may be obtained by adding sodium carbonate to ferrous solutions. It is readily oxidized to ferrous hydrate on exposure to the air; is insoluble in pure water, but soluble in water containing carbon dioxide, and is, therefore, present in many natural waters. IRON 215 The ferri carbonas saccharatum is ferrous carbonate to which sugar has been added to prevent decomposition, and is prepared by mixing solutions of ferrous sulphate and sodium bicarbonate and adding sugar ; the mixture is then evaporated to dryness. It is a greenish-gray powder. 422. Ferrous Phosphate—Triferrous Phosphate (Fe3 (P04)2), is a white precipitate formed by adding sodium phosphate to a solution of a ferrous salt. It turns blue on exposure to the air, a part being converted into ferric phos- phate. The ferri phosphas (U. S., Br.) is a mixture of these two salts. It is insoluble in water; slightly soluble in water containing carbonic dioxide or acetic acid. A soluble or acid phosphate exists in the shops. A phosphate of iron, that turns blue on exposure to the air, exists in the lungs, phthisis, in bones which have been buried for some time, and occasionally in pus. 423. Ferrous Sulphide—Protosulphide (FeS), may be obtained, first, by fusing a mixture of sulphur and iron filings at ordinary temperatures, although the union will often occur slowly ; second, by precipitation of a ferrous salt with alkaline sulphides. The first method forms brownish, brittle, fusible masses; the latter yields a black powder. Ferrous sulphide is not decomposed by heat, but is decomposed by sulphuric acid, with formation of ferrous sulphate and hydrogen sulphide. It occurs in the faeces of persons taking chalybeate waters and preparations of iron. 424. Ferrous Lactate—Ferri Lactas (U.S.), (Fe(C:jH50:j), is obtained by dissolving iron filings in lactic acid. It forms light yellow crystals, soluble in wrater, insoluble in cold alcohol. 425. Ferrous Oxalate—Ferri Oxalas (U. S.), (Fe(C204), is made by dissolving iron in a solution of oxalic acid. A bright yellow, crystalline powder, slightly soluble in hot water. 426. Ferrous Tartrate (FeC4H406) is formed by dissolving iron in a hot, strong solution of tartaric acid. 427. Ferric Compounds—Ferric Oxide—Sesquioxide of Iron (Fe203), exists in nature as haematite, and may be formed by heating the oxygen compounds of iron in the air. On a large scale, it is obtained by distilling ferrous sulphate, which first turns white, from loss of water; then yellow, owing to the formation of an oxyhydrate, and finally to a brick-red, ferric oxide. It is used as a polishing material, under the names of colcothar, red crocus, jewelers’ rouge, caput mor- tuum, or Venetian red. 216 INORGANIC CHEMISTRY. Ferrous-Ferric Oxide (Fe304 = Fe0Fe203) occurs native as magnetite. It may be obtained by conducting steam over ignited iron. It constitutes the natural magnets. 428. Ferric Hydrate — Ferri Oxidum Hydratum (U. S., Br.), (Fe2(OH)6), is a voluminous, reddish-brown, gela- tinous mass, precipitated by alkaline hydrates from ferric solu- tions. When dried at 100°C. (212°F.), it loses 2H20. Freshly precipitated ferric hydrate is soluble in a solution of ferric chlo- ride or acetate, and if such a solution is dialysed, the iron salt diffuses, leaving the pure ferric hydrate on the dialyser. The dialysed iron so obtained is coagulated by heat, acids or alka- lies, into a jelly-like mass. It is a good antidote in arsenic poisoning. 429. Ferric Chloride—Sesquichloride of Iron—Per- chloride of Iron—Ferri Chloridum (U.S.), (Fads'), may be obtained anhydrous in volatile, deliquescent plates by heating iron in chlorine gas. It may be formed in solution by dissolving iron in hydrochloric acid and adding a little chlorine water or nitric acid; or by dissolving the oxide or hydrate in hydrochloric acid; or by the action of chlorine on a solution of ferrous chloride. To obtain the solid, it is only necessary to evaporate and crystallize. It is prepared in pharmacy by the last method. It forms yellow, crystalline masses or rhombic plates, readily soluble in water, alcohol or ether. The Liq. ferri chloridi (U. S.), or Liq. ferri perchloridi (Br.), is an aqueous solution containing an excess of acid. The U. S. P. preparation contains 37.8 per cent, of ferric chloride. The Tinct. ferri chloridi (U. S.) is the same, diluted with alcohol, and contains also ethyl chloride and ferrous chloride. 430. Ferric Sulphate (Fe2(S04)3) is obtained by dissolving the oxide in sulphuric acid. It remains, after evaporating the solution, as a white mass, which dissolves readily in water, form- ing the Liquor ferri tersulphatis (U. S.). This solution is a dark, reddish-brown liquid, having an acid, styptic taste. Another sulphate, which is basic, is formed by treating ferrous sulphate, 77 parts, with nitric acid, and evaporating, after add- ing 7 parts sulphuric acid. This, in solution, is the Liq. ferri subsulphatis, or Mon- sel’s solution. 431. Ferric Alum—Ammonio-ferric Alum—Ferri et Ammonise Sulphas (U.S.P.), (NH4)2Fe2(S04)4.24H20), is pre- pared by adding a solution of ammonium sulphate to a solution of IRON. 217 ferric sulphate, and evaporating down and allowing it to crystal- lize. The crystals are colorless or pale amethyst, regular octahedra, soluble in 3 parts of water at 15°C. (59°F.). The solution has an acid reaction and an astringent taste, but not so astringent as ferric sulphate. It gives the reactions for ferric iron, ammonia and sulphates. It is employed in medicine as an astringent, both internally and locally. 432. Ferric Nitrate (Fe2(N03)6) is formed, together with ferrous nitrate, by dissolving iron in nitric acid. The Liq. ferri nitratis (U. S.), or Liq. ferri pernitratis (Br.), is an aqueous solution of ferric nitrate. It crystallizes in rhombic prisms with 18H20, or in cubes with 12H20. 433. Scale Compounds of Iron.—These are certain salts of iron, mostly with organic acids, which do not crystallize readily, but are put into the market in the form of thin scales. They are prepared by evaporating their solution to a thick, syrupy consistence, spreading upon glass plates, drying, and then detaching the thin scales from the glass. They are all used in medicine. Ferri Citras (U. S.)—citrate of iron—is prepared by the action of citric acid upon soluble salts of iron, usually the sul- phate. After its aqueous solution has been evaporated upon glass, it forms beautiful, thin, transparent scales, of a garnet-red color, slowly soluble in cold, but freely in hot water, and possess- ing a mild, chalybeate taste. Ferri et Ammoniae Citras (U. S., Br.)—citrate of iron and ammonia—is formed by treating a solution of citrate of iron with ammonium hydrate, and evaporating at a temperature that should not exceed 38°C. (100.4°F.). It also forms garnet-red scales, which are readily and wholly soluble in water, forming a solution that is neutral to litmus paper and slightly styptic in taste. Ferri et Ammoniae Tartras (U. S.)—tartrate of iron and ammonia—a double salt, is formed by the action of tartaric acid upon ferric and ammonic hydrates. Upon evaporation of its solution, garnet-red scales remain, which are slowly soluble in water. Their solution is neutral to test paper, and is of a sweetish, rather pleasant taste. Ferri et Potassae Tartras (U. S.)—Ferrum Tartaratum (Br.)—potassio-tartrate of iron—may be obtained by dissolving ferric hydrate in a solution of acid tartrate of potassium, and evaporating on glass. It forms ruby-red plates, having about the same properties as the ammonio-tartrate. 218 INORGANIC CHEMISTRY. Ferri et Quiniae Citras (U. S., Br.)—citrate of iron and quinine—contains citric acid, ferric hydrate and quinia citrate. It forms transparent scales of a greenish tint, slowly soluble in cold water, but freely in hot water, forming bitter, slightly styptic solutions. Ferri et Strychniae Citras closely resembles the citrate of iron and ammonia in appearance, but has a bitter taste, and gives a white precipitate with ammonium hydrate. It is prepared by adding a solution of strychnine citrate to a solution of ferric citrate, evaporating on a water bath to a syrup, and drying on glass. Ferri Phosphas (U. S., Br.), (Fe2(P04)2).—Phosphate of iron occurs as the result of a double decomposition between ferric sulphate and sodium phosphate. It forms a bright, slate- colored powder, insoluble in water, but soluble in acids. Ferri Pyrophosphas (U. S.), (Fet(P207)3).—Pyrophosphate of iron is formed by adding a solution of sodium pyrophosphate to a solution of a ferric salt. It does not crystallize, but forms scales upon evaporating its solution. These are thin, apple- green in color, turn dark on exposure to the air, and are soluble in water, but not in alcohol. Ammonium hydrate produces no precipitate in its solutions, but sodium hydrate does. The officinal salt contains 48 per cent, of anhydrous ferric pyrophosphate. NICKEL GROUP. Nickel = 59. Cobalt = 59. 434. These elements are often included with the members of the iron group, to which they bear a certain resemblance, but from which they differ in not forming, so far as is known, com- pounds similar to the ferrates, chromates or manganates. Furthermore, no compounds of nickel or cobalt analogous to the salts of chromic or manganic acids are known. NICKEL. 435. Occurrence, Preparation and Properties.—This metal is found native in meteorites. Its most common ores are Niccolite (Ni2As2)and Gersdorffite (NiS2)2As2). These ores of nickel, however, usually also contain cobalt, and the cobalt- ous ores are commonly nickel bearing also. The separation of nickel from its ores is a very complicated process, and for an account of it, the reader is referred to works on metallurgy. It may be prepared chemically pure by igniting its oxalate or car- LEAD GROUP. 219 bonate in a stream of hydrogen. This metal is silver white, tenacious and very lustrous; sp. gr. 9.1. It is attracted by the magnet. It does not alter in the air, but dissolves in the mineral acids, especially nitric. 436. Compounds.—The following are the most common of the nickel compounds ; they are all ous compounds, having the general form NiR2, and all possess a green color: nickelous hydrate (Ni(OH)2), nickelous chloride (NiCl2 + 6H20), nickelous cyanide (Ni(CN)2), nickelous sulphate (NiS04 + 7H20) and nickelous sulphide (NiS). Nickelic oxide (Ni203) and hydrate (Ni2(OH)6) exist, and are similar to the corresponding cobalt compounds. Nickel is used largely in certain alloys and for electro-plating. COBALT. 437. Occurrence,Preparation, Properties,etc.—Smalt - ite (CoAs2) and cobaltite (CoAs2. CoS2) are the most commonly occurring native ores of cobalt. It is prepared in the same manner as nickel. It is a reddish-white metal, tenacious, and fusible with great difficulty; sp. gr. 8.9. Its other properties are very similar to those of nickel. 438. Cobalt Compounds are also chiefly ous, correspond- ing to the general form CoR2. Those containing water have a reddish color ; the anhydrous compounds are blue. The cobaltous compounds are, cobaltous chloride (CoCl2), cobaltous hydrate (Co(HO)2), cobaltous sulphate (CoSO* + 7H20), cobaltous nitrate (Co(N03)2 + 6H20), and cobalt- ous sulphide (CoS). The cobaltic compounds are, cobaltic oxide (Co203), and cobaltous-cobaltic oxide (Co304 = Co203CoO). The latter corresponds to magnetite (Fe3Ot). Co = 59. LEAD GROUP. Lead, Pb = 207. 439. Occurrence.—The most abundant ore found native is Galena, or Galenite (PbS). Other ores are Cerussite (PbC03), Crocoisite (PbCr04), Wulfenite (PbMo04) and pyromasphite (Pb3(P04)2). 440. Preparation.—For this purpose galenite is almost exclusively employed. The ore is first roasted in the air, by 220 INORGANIC CHEMISTRY. which a portion of the lead sulphide is converted into oxide and another part into sulphate. and PbS + 30 = PbO + S02 PbS + 40 = PbS04. These two products are then strongly heated in a reverberatory furnace, when they react as follows:— and 2PbO + PbS = 3Pb + S02 PbS04 + PbS = 2Pb + 2S02 If the galena contain much silver, this is separated by crystal- lization and cupellation. 441. Properties.—Lead is a bluish-white metal, brilliant upon freshly cut surfaces, but soon tarnishes. It is soft and pliable, but not very malleable or ductile; specific gravity 11.37. It fuses at 334° C. ( 633° F.). If melted, it does not, on cooling, return to its original volume. It is a poor conductor of elec- tricity, but a better conductor of heat. When exposed to the air, it oxidizes slightly. It is not acted upon by pure water deprived of air, but, by the contact of air and water, it oxidizes to the hydrate (Pb(OH)2), which dissolves slightly in water. If the water contains carbon dioxide, carbon- ates or sulphates, very little lead goes into solution, but it‘ is coated with an insoluble layer of lead carbonate or sulphate. (If carbon dioxide be in excess, as in soda water, the carbonate formed is somewhat soluble in the water). The solvent action of water upon lead is increased, however, by the presence of nitrates and nitrites. These facts are of great practical importance, as lead pipes are very frequently employed for conducting water. Sulphuric and hydrochloric acids have but little effect on lead, especially if cold, owing to the insolubility of its sulphate and chloride. Nitric acid dissolves it readily. Zinc, tin and iron precipitate this metal from its solution. There are several useful alloys of lead. Alloyed with an equal part of tin, it fuses at 186° C. (366.8° F.) and is used for soldering (soft solder). Type-metal is an alloy of four or five parts of lead and one of antimony ; the proportions vary considerably. 442. Lead Oxide—Protoxide—Massicot—Litharge— Plumbi Oxidum (U. S., Br.), (PbO), is prepared by heating lead, its carbonate or nitrate, in the air. If it fuses, it consti- tutes litharge ; if not, massicot. The former is a reddish- yellow or brown mass of rhombic scales; the latter is a yellow, LEAD GROUP. 221 amorphous powder, differing from litharge in color and texture, but not in composition. Lead oxide has strong basic properties. It absorbs carbon dioxide from the air and imparts an alkaline reaction to water, in which it dissolves as hydrate. Like other strong bases, it saponifies fats and forms lead soaps, as lead plaster. It dis- solves readily in nitric or hot acetic acid, with formation of nitrate or acetate of lead. It fuses at a red heat. If fused in earthen crucibles, it forms a silicate, and thus perforates the crucible. When heated to 300° C. (572° F.) in contact with air, it is oxidized to minium, or a bright red powder (red lead). 443. Plumboso-plumbic Oxide—Minium—Red Lead (Pb304), or (2Pb0.Pb02), is prepared as already stated, by roast- ing litharge at a temperature of 300° C. (572° F.), and is used as a pigment and in the manufacture of glass. Its composition is probably expressed by the formula Pb:!04; or, as one molecule of the dioxide combined with two of the monoxide; or, as the lead salt of plumbic acid. It is a brilliant red powder, of specific gravity 8.62. When strongly heated, or subjected to the action of reducing agents, it is converted into litharge. Nitric acid dissolves the monoxide, leaving the dioxide, and changing its color to brown. As occurring in commerce, it is frequently contaminated with oxides of iron or brickdust. It should dissolve in dilute nitric acid to which a little sugar has been added. 444. Lead Dioxide—Peroxide of Lead—Puce Oxide of Lead—Binoxide of Lead—Plumbic Anhydride—may he prepared by dissolving the monoxide out of minium with dilute nitric acid, or by the action of chlorine upon lead carbon- ate suspended in water. It is a dark, reddish-brown powder, insoluble in water; specific gravity 8.903 to 9.190. Heat drives off half its oxygen, converting it into monoxide. It is a valuable oxidizing agent. 445. Plumbic Acid is formed as crystalline plates at the positive electrode when alkaline solutions of the lead salts are subjected to electrolysis. With the alkaline hydrates, lead dioxide dissolves to form well defined but unstable plumbates. Potassium plumbate may be obtained in cubic crystals by dissolving the hydrate in potassium hydrate, and cooling the solution. It is decomposed by water. 446. Lead Chloride (PbCl2) separates as a white precipitate when hydrochloric acid is,added to a solution of a lead salt. It 222 INORGANIC CHEMISTRY. is nearly insoluble in cold water, but dissolves in thirty parts of hot water, from which solution it crystallizes on cooling, in white, shining needles. At a red heat, it fuses to a horn-like •mass. 447. Lead Iodide—Plumbi Iodidum (U. S., Br.), (Pbl2), is precipitated from lead solutions by potassium iodide, as a bright yellow, crystalline powder. It is practically insoluble in cold water, but more soluble in boiling water, from which it crystallizes on cooling, in beautiful, gold-colored, glistening crystals. Exposed to light and moisture, it decomposes, with liberation of iodine. 448. Lead Nitrate—Neutral Lead Nitrate—Plumbi Nitras (U. S., Br.), (Pb(N03)2), is obtained by dissolving lead or its oxides in excess of nitric acid. It forms anhydrous, octa- hedral crystals, soluble in 1.98 parts of water at 17.5°C. (63.5°F.), and in 0.7 parts at 100°C. (212°F.). At a red heat, it melts and is decomposed into PbO,N02 and oxygen, and at a higher temperature, into PbO. 449. Lead Sulphate (PbS04) occurs in the mineral Anglesite in rhombic crystals, isomorphous with barium sul- phate. It is produced by the double decomposition between a sulphate and a soluble lead salt. It is insoluble in water, but readily soluble in concentrated sulphuric acid. The commercial acid always contains it. 450. Lead Carbonate—Plumbi Carbonas (U. S., Br.), (PbC03), occurs as Cerussite. It may be produced by double decomposition between a lead salt and a carbonate, or by passing carbon dioxide through a solution of a lead salt. White lead is usually prepared commercially by treating thin sheets of lead with acetic acid and then exposing the acetate to carbon dioxide. The lead, rolled into sheets, is placed in earthen jars containing a small quantity of vinegar at the bottom, but not in contact with the lead. Great numbers of the jars after being thus charged are buried in stable manure or spent tan bark. By the decomposition of the bark or manure, considerable carbon dioxide and heat are produced. The heat volatilizes a portion of the vinegar, which, acting upon the lead, produces the acetate (Pb(C2H302)2). The carbon dioxide acting upon the acetate converts it into acetic acid, which acts upon a fresh portion of lead, and a basic or hydro-carbonate of lead. 2PbCOs. Pb02H2 or PbO—HC03—Pb—C03—PbO—H. After the lapse of a considerable time, the pile is taken down, LEAD GROUP. 223 the sheets are taken out, and the carbonate detached from them by passing them through rollers or by pounding. The white powder is then ground with oil and sent into the market as “ White Lead.” White lead is largely used in oil painting, forming a part of all but the darkest colors. As it is poisonous and is darkened by the action of hydrogen sulphide in the atmosphere, it is at present being more and more replaced by zinc white (ZnO) and permanent white (BaSO*). 451. Lead Sulphide (PbS) occurs in the mineral galena. It is precipitated from solutions of lead salts by hydrogen sul- phide or alkaline sulphydrates as a black powder. The native sulphide is bluish-gray and has a metallic lustre ; sp. gr. 7.58. The sulphide obtained by precipitation has a sp. gr. of 6.924. It is insoluble in dilute acids. 452. Lead Acetate—Salt of Saturn—Sugar of Lead— Plumbi Acetas (U. S., Br.), (Pb(C2H302)2), is prepared by dissolving litharge in acetic acid ; or by exposing lead in contact with acetic acid to the atmosphere, evaporating and crystallizing. It forms large, oblique rhombic prisms, having a sweetish, me- tallic taste. It dissolves in 1.5 parts of water and in 8 parts of alcohol, forming solutions which react acid upon test paper. On exposure to the air, the crystals effloresce upon the surface and are partly converted into carbonate. Several subacetates, as basic acetates, are known. The only one requiring mention is that having the formula PbOH (C2H302)2PbO. This is the chief con- stituent of Liq. plumbi subacetatis (U. S., Br.), or Gou- lard’s extract, which is obtained by boiling a solution of the neutral acetate with lead monoxide in fine powder. When ex- posed to the air, this solution becomes milky from the formation of lead carbonate. 453. Lead Chromate (PbCr04) is formed by precipitating lead nitrate with potassium chromate. Under the name of chrome yellow, it is used as a pigment. Very recently, its fraudulent use as an artificial coloring agent in manufactured food products has been discovered. It is insoluble in water, but soluble in alkalies. 454. Physiological Action of Lead. All of the com- pounds of lead that are soluble, and those that are themselves insoluble but that are readily convertible into soluble compounds by the action of air, water or the digestive fluids, are poisonous. The chronic form of lead poisoning, painter’s colic, is very common, and is produced by the continuous absorption of small 224 INORGANIC CHEMISTRY. quantities of the metal or its compounds, either by the skin, lungs, or stomach. Although metallic lead is inert, its absorp- tion will cause symptoms of poisoning from its being converted within the body into poisonous compounds. Some of the methods by which it may be introduced are, the drinking of water that has been in contact with the metal; the use of food, tobacco, etc., that has been wrapped in tin-foil containing lead ; the drinking of beer or other beverages that have been kept in pewter vessels; the handling of the metal or its alloys by arti- sans. Almost all of the commoner compounds of lead may give rise to the chronic poisoning. Probably the carbonate is the cause of more cases than any other lead compound in painters, artists, manufacturers of paint, and persons sleeping in freshly painted apartments. Acute lead poisoning is comparatively rare and is not often fatal. It is generally caused by the ingestion of a single large dose of the acetate, subacetate, carbonate or red lead. When it occurs, magnesium sulphate should be given, as it forms an insoluble lead sulphate. If the metal be once absorbed, it is eliminated slowly, as it tends to become fixed by combination with the albuminoids of the body. This combination is rendered soluble by potassium iodide. It is eliminated by the urine, perspiration and bile. Great caution is necessary in drawing conclusions, in case traces of lead are found in the body after death, on account of the many ways that it may be introduced. COPPER GROUP. 455. Each of these elements forms two series of compounds. One series contains the group >J or (Hg2)" and the com- pounds are known as the cuprous and mercurous compounds, respectively ; the other contains a single dyad atom, and is des- ignated by the termination ic. Copper = 63.5. Mercury = 200. COPPER. 456. Occurrence.—This metal occurs in the free state in large masses, or crystallized in cubes and octahedra. It is found in the vicinity of Lake Superior, in China, Japan, Sweden, and in the Urals. Its most important ores are: cuprite (Cu20), Cu = 63.5. COPPER. 225 malachite and azurite (basic carbonates), chalcocite (Cu2S), and chalcopyrite, or copper pyrites (CuFe2S). 457. Preparation.—The mixed copper ores are first roasted in the air, by which process a portion of the copper sulphide is converted into oxide; this is then roasted with silica fluxes and carbon. By this process the iron sulphide is converted into silicate, and is drawn off with the slag. After several repetitions of this process, the so-called copperstone is obtained; this contains both the sulphide and oxide. By repeated roasting and heating, the copper oxide reacts upon the sulphide, and metallic copper results. Some poor ores are first treated with sulphuric acid, and the resulting sulphate is then treated with scrap iron, which precipitates the copper in the metallic state. Chemically pure copper is obtained by heating the pure oxide in a stream of hydrogen, or by electrolysis. 458. Properties.—Copper is a red metal by reflected light, while thin leaflets transmit a green light. It is soft, ductile and tenacious; a good conductor of heat and electricity ; specific gravity 8.914 to 8.952. In dry air it under- goes no change ; but in moist air it gradually becomes coated with a thin layer of green basic carbonate. When heated, it oxidizes to black cupric oxide (CuO). Hot sulphuric, nitric and hydrochloric acids dissolve it, with liberation of sulphur dioxide, nitrogen dioxide, and hydrogen, respectively. With organic acids it forms soluble salts in the presence of air and moisture; hence, acid fruits should not be kept in copper vessels. 459. Cuprous Compounds.—These are very unstable, absorb oxygen, and are converted into cupric compounds. If the formulae CuCl, Cul, Cu20 and Cu2S are correct, copper in the cuprous compounds would appear, like silver, to be univalent. It has never been determined, however, whether these formulae really express the true molecules. Copper compounds are not volatile, and we have no means of ascertaining the size of the molecule. As has already been stated, most chemists believe that in the cuprous compounds copper is bivalent, and that they contain the group Cu,//, whose valence is always two. . 460. Cuprous Oxide — Suboxide, or Black Oxide (Cu20), occurs in nature as cuprite. It is obtained artificially by boiling an alkaline solution of grape sugar and copper sul- phate. It precipitates as a bright red powder. (Fehling s and Trommer’s tests.) The hydrate (Cu2(OH)2) is precipitated by the alkalies, from hydrochloric acid solutions of Cu2Cl2, as a yellow powder. 226 INORGANIC CHEMISTRY. 461. Cuprous Chloride—Subchloride, or Protochloride (CuCl or Cu2Cl2), is produced, together with cupric chloride, by igniting metallic copper in chlorine gas; by dissolving cuprous oxide in hydrochloric acid without contact of air; or by the action of many reducing agents upon solutions of cupric chloride. It is a heavy white powder, rapidly becoming green in the air, owing to the absorption of oxygen, and formation of cupric chloride (Cn/gy. It dissolves in concentrated hydrochloric acid, but not in water. With carbon monoxide it forms a crystal- lizable compound. Its hydrochloric acid solution is used in gas analysis to absorb this gas. 462. Cuprous Iodide (Cu2I2) is precipitated, together with iodine, from soluble cupric salts, by potassium iodide. 2CuS04 + 4KI = 2K2S04 + Cu2I2 + I2. On dissolving out the iodine with ether, the iodide is left as a gray insoluble powder. 463. Cuprous Sulphide — Subsulphide, or Protosul- phide (Cu2S), occurs in nature as chalcocite, as soft, fusible, gray crystals ; also in many double sulphides, among which the most important is the double sulphide of copper and iron, or copper pyrites. 464. Cupric Compounds—Cupric Oxide—Binoxide — Black Oxide (CuO), is prepared by heating copper turnings to redness in the air, or by calcining the nitrate. It forms a black amorphous powder, readily reduced by heated charcoal, hydrogen, or the alkaline metals, to the metallic state. If heated in the presence of organic substances, it oxidizes them completely, and is thereby reduced to metal. It is used in organic analysis for this purpose. 465. Cupric Hydrate (Cu(OH)2) is formed as a volumin- ous bluish-white precipitate, when sodium or potassium hydrate is added to a solution of a copper salt. When heated, even under water, it becomes dehydrated and changed to black cupric oxide. Copper oxide and hydrate dissolve in ammonium hydrate, forming a dark-blue solution. This solution is often used as a solvent for cellulose, from which solution acids precipitate it again. (See Celluloid.) ' . 466. Cupric Chloride (CuCl2) is formed by dissolving cupric oxide or carbonate in hydrochloric acid. From aqueous solutions it crystallizes in bright green, rhombic needles with COPPER. 227 12H20. It is readily soluble in water and alcohol. When heated, it parts with its water, and forms anhydrous cupric chloride, which at a red heat gives off chlorine. 2CuC12 + heat = Cu2Cl2 + Cl2. Cupric bromide resembles the chloride. The iodide is not known. 467. Cupric Sulphate — Blue Vitriol — Blue Stone — Cupric Sulphas (U. S., Br.), (CuS045II20), may be prepared, first, by roasting chalcocite; second, from the water of copper mines ; third, by exposing copper moistened with dilute sulphuric acid, to the air; fourth, by dissolving copper in hot, concentrated sulphuric acid. It forms large, blue triclinic crystals, which dis- solve in 2.71 parts of water at 19°C. (66.2°F.), and in 0.55 parts of water at 100°C. (212°F.). It loses four molecules of water at 100°C. (212°F), while the fifth separates above 200°C. (392°F.), leaving a white amorphous powder, which readily takes up water, and in so doing, resumes its blue color. Solutions of copper salts have a blue color, acid reaction and metallic, styptic taste. Ammonium hydrate added to a solution of copper sulphate precipitates a bluish-white cupric hydrate, which dissolves in an excess of the alkali, forming a deep blue solution. Alcohol floated on this solution causes to separate long, right rhombic prisms having the composition CuS044NH3H20, which are very soluble in water. Their solution constitutes cuprammonium sulphate, and they exist mixed with other substances in the cuprum ammoniatum (U. S.). 468. Copper Carbonates.—The neutral carbonate (CuC03) is not known. When alkaline carbonates are added to solutions of copper salts, the basic carbonate separates as a green precipi- tate, having the formula CuC03.2Cu(0H2). This occurs in nature, especially in Siberia, as malachite. Another basic salt, tricupric carbonate, or sesquicarbonate of copper, is the beautiful blue azurite. 469. Copper Arsenite—Scheele’s green, is prepared by adding a solution of sodium or potassium arsenite to a solution of a copper salt. It is a green powder, composed of copper arsenite and hydrate. It is insoluble in water, but soluble in ammonium hydrate or the mineral acids. It is exceedingly poisonous, but is often used as a pigment to color wall papers, toys, and even confectionery. . Schweinfurt Green — Mitis Green, or Paris Green (Cu (C2H302) + 3(As2Cu04), is the commonest and most danger- 228 INORGANIC CHEMISTRY. ous of the cupro-arsenical pigments. It is prepared by adding a concentrated solution of cupric acetate to a boiling solution of arsenious acid. It is an insoluble, green, crystalline powder, decomposed by prolonged boiling in water, by aqueous solutions of the alkalies, and by the mineral acids. It is also soluble in ammonium hydrate. 470. Copper Acetates. The diacetate (Cu(C2H302)2) is formed by the decomposition of a solution of copper sulphate by lead acetate. It separates in large, bluish-green, prismatic crystals, with one molecule of H20, which it loses at 140°C. (284°F.) The dry salt when heated to 250°C. (482°F.), decom- poses with liberation of glacial acetic acid. Basic Acetates—Verdigris—Cupric Subacetas (U. S.), is a complex mixture of copper acetate and hydrate. It is pre- pared by exposing to the air piles composed of alternate layers of grape skins and copper plates, and after some time removing the bluish-green coating from the copper plates.* 471. Copper Pigments.—The most important are : Brigh- ton Green, a mixture of copper acetate and chalk. Bruns- wick Green, orginally an impure chloride, but now generally a mixture of carbonate and chalk. Mountain Green, or Mineral Green, is a native green carbonate of copper, some- times containing orpiment. Neuwieder Green, another name for mineral green or Schweinfurt green, mixed with gypsum or barium sulphate. Green Verditer is a mixture of the basic carbonate, oxide, and chalk. 472. Physiological.Action of Copper.—Until recently, toxicologists were universally of the opinion that all the copper salts are poisonous. Of late, however, this has been considerably modified. Most of the copper compounds have an irritant, local action if brought into contact with the gastric or intestinal mucous membrane, causing vomiting of greenish matter, cramps, etc. On the other hand, there are numerous instances in which severe illness, characterized by nervous and other constitutional symp- toms, has followed the use of food that has been in contact with imperfectly tinned copper vessels. Some such cases have proven fatal. It has been conclusively shown, however, that pure and non-irritating copper compounds may be taken in considerable quantity without any bad results, excepting vomiting. Copper sulphate is frequently used as an astringent in medi- * The term verdigris is now often popularly applied to the green carbonates, hydrates, or salts of organic acids, which accumulate on the surface of copper. MERCURY. 229 cine, and has been recommended in cholera and dysenteric troubles. This salt may be taken in considerable doses, with only an emetic effect. Cases of acute poisoning are not common, but many are recorded. Chronic poisoning is occasionally seen in those who work in copper, characterized by colicky pains, emaciation, impaired digestion, diarrhoea, and often a catarrhal cough. In most cases, there is a green line on the margin of the gums. Copper is very likely to become contaminated with arsenic; and it is possible that some of the cases of reported copper poisoning ought to be attributed to arsenic. The organic salts of copper seem to be more poisonous than the inorganic. Canned peas, pickles, and other fruits are often contaminated with copper, and the manufacturers have frequently been pun- ished by fines ; but there exists a difference of opinion as to the dangers of copper in such goods. As long, however, as there is a chance for doubt, sanitary authorities should prohibit its use.* The chemist must remember that most articles of food contain traces of copper. The treatment of cases of irritant copper poisoning should con- sist in the exhibition of milk, white of egg, and other albuminoid substances, with which the copper salt may form an inert com- pound. Emesis should be induced if it has not taken place spontaneously. MERCURY. 473. Occurrence.—Mercury occurs in nature principally as cinnabar, or, rarely, in the form of small particles scattered through rocks. It is found in Spain, Peru, China, Japan, Cali- fornia and Mexico. 474. Preparation.—The native sulphide, or cinnabar, is roasted in reverberatory furnaces, thus burning out the sulphur, and distilling off the mercury and condensing it. Or, it is some- times simply heated with iron, which removes the sulphur and sets free the mercury, which distills over. Commercial mercury usually contains small quantities of qther metals, owing to its great tendency to amalgamate with them. To remove these it is re-distilled, or treated with very dilute acids by pouring it in a thin stream into them. When pure, mercury pours from a glass surface without leaving a streak, and the single droplets retain their globular form, and do not form a tail or adhere to the glass. Hg = 200. * This has been done in Brooklyn, N. Y., where one case of fatal poisoning has occurred from a pickle containing copper. 230 INORGANIC CHEMISTRY. 475. Properties.—Mercury is the only liquid metal at ordinary temperatures. Its specific gravity is 13.596. At 40° C. it solidifies, and crystallizes in octahedra. It is somewhat volatile at ordinary temperatures, and boils at 360° C. (680° F.). Its vapor has a density of 100; specific gravity 6.97 (Air = 1). Its molecular weight, therefore, is 200 ; and as its atomic weight is also 200, its molecule, like that of cadmium, is composed of orte atom. If pure and at ordinary temperatures, it is not altered in the air; at a temperature near the boiling point, it is coated with a thin film of mercuric oxide. Hot sulphuric acid converts it into mercuric sulphate, with evolution of sulphur dioxide. It dissolves readily in dilute nitric, but not in hydro- chloric acid. Mercury dissolves all metals but iron, to form amalgams. Tin amalgam is used for coating mirrors. 476. Mercurous Compounds.—Mercurous Chloride— Protochloride — Mild Chloride—Calomel — Hydrargyri Chloridum (U.S.)—Hydrargyri Subchloridum (Br.),(HgCl or Hg2Cl2), is usually prepared by the mutual decomposition of sodium chloride, mercuric sulphate and mercury. After mix- ing thoroughly in a mortar, the mixture is heated, when the calomel sublimes. HgS04 + 2NaCl + Hg = Na2S04 + Hg2Cl2. By this method, mercuric chloride is also formed in varying quantities, and should be removed by washing the product with boiling distilled water, until the washings no longer form a pre- cipitate with ammonium hydrate. Mercuric chloride may be detected in calomel by its forming a black stain upon a bright iron surface dipped in a mixture of calomel and alcohol; or, by the production of a black stain by hydrogen sulphide in water that has been filtered through calo- mel so contaminated. Calomel crystallizes when sublimed, in radiating quadratic prisms ; but if precipitated from solutions of mercurous salts by hydrochloric acid, it forms a heavy, white, amorphous powder. Heated to about 500° C. (932° F.), it sub- limes without fusing, is insoluble in cold water and alcohol, and dissolves in boiling water to the extent of 1 part in 12,000. If boiled for a long time with water, it partly decomposes, mercury being deposited, and mercuric chloride passing into solution. Strong acids convert it into mercuric salts and free mercury. With ammonium hydrate it blackens, with formation of mercur-amidogen chloride. Hg2Cl2 + 2NH4OH = NH4C1 + NH2Hg2Cl + 2H20. MERCURY. 231 Hydrochloric acid and alkaline chlorides convert it into mercuric chloride ; this may occur in the stomachs of persons who use large quantities of salted food, as on board ship. Alkaline iodides convert it first into mercurous iodide, which is then decomposed by an excess of the alkaline iodides into mercuric iodide and mercury. 477. Mercurous Iodide—Protoiodide, or Yellow Io- dide— Hydrargyri Iodidum Viride (U. S., Br.), (Hgl or Hg2I2), is prepared by triturating 200 parts of mercury with 127 parts iodine and a little alcohol, until a green paste is formed. It may also be prepared by precipitation from a solution of Hg2(N03)2 with KI. It is a greenish-yellow, amorphous pow- der, insoluble in water and alcohol. It turns brown and vola- tilizes when heated. Light decomposes it into mercuric iodide and mercury. 478. Mercurous Oxide—Protoxide, or Black Oxide (Hg20), is formed by the action of sodium hydrate up >n mercurous salts. It is a brownish-black, tasteless powder, which sunlight decomposes into mercuric oxide and mercury. Mineral acids convert it into the corresponding mercurous salts. It exists in the lotio hydrargyri nigri (Br.), or black wash. 479. Mercurous Nitrate (HgN03 or Hg,(NOjV) is formed by digesting an excess of mercury with somewhat diluted nitric acid, until short prismatic crystals separate. The crystals effloresce in the air. Water decomposes this salt into the acid salt, which goes into solution, and basic mercuric nitrate (*<°*)f separates as a yellow powder. Water acidu- lated with nitric acid dissolves it, but it soon oxidizes and becomes mercuric nitrate. By adding metallic mercury to the solution, this oxidation is prevented to a great degree, or after oxidation reduces it back to the ous state. Hg(N03)2 + Hg = Hg2(N03)2. 480. Mercurous Sulphate (HgS04) is formed by gently warming an excess‘of mercury with sulphuric acid. It separates as a yellow crystalline precipitate when sulphuric acid is added to mercurous nitrate solution. 481. Mercuric Compounds.—In these, mercury is biva- lent ; they are represented by the formula HgR2- _ The mercuric compounds are always formed when mercury is dissolved in excess of acid; when the opposite is the case, the ous compoun Is 232 INORGANIC CHEMISTRY. form. The addition of metallic mercury to the mercuric com- pounds converts them into mercurous compounds, while oxidizing agents produce the opposite effect. 482. Mercuric Chloride—Bichloride—Corrosive Sub- limate—Hydrargyri Chloridum Corrosivum (U. S.), Hy- drargyri Perchloridum (Br.), (HgCl2), may be produced by dissolving mercuric oxide in hydrochloric acid. On a large scale, it is prepared by subliming a dried mixture of mercuric sulphate and sodium chloride. HgS04 + 2NaCl = HgCl3 + Na2S04. It crystallizes by sublimation in rectangular octahedra; from solution in fine, right rhombic, needle-like prisms. At ordinary temperatures, it dissolves in 15 parts of water, and at 100° C. (212° F.), in 3 parts ; it is still more soluble in alcohol. It dis- solves freely in hot hydrochloric acid, which solution gelatinizes on cooling. Its specific gravity is 5.4. In aqueous solution, it tends to reduce into metallic mercury and calomel. Sodium or ammonium chloride prevents this change. Zinc, cadmium, nickel, iron, lead, copper and bismuth, remove most of its chlorine, reducing it either to metallic mercury or calomel. Sulphuric, nitric and hydrochloric acids all dissolve it without decompo- sition-. With albumen, it forms a white precipitate, insoluble in water, but soluble in excess of albumen solution, or in solutions of alkaline chlorides. 483. Mercur-Ammonium Chloride—White Precipi- tate—Ammoniated Mercury—Hydrargyrum Ammoni- atum (U. S., Br.), (NH.2HgCl), is thrown down as a heavy white precipitate, by adding a slight excess of ammonium hydrate to a solution of mercuric chloride. It is insoluble in alcohol, ether, and cold water. Hot water decomposes it, with the separation of a heavy yellow powder. It sublimes without fusing. 484. Mercuric Iodide—Biniodide, or Red Iodide— Hydrargyri Iodidum Rubrum (U. S., Br.), (Hgl2), is formed by the direct union of mercury and iodine, when the two are triturated in a mortar. When solutions of mercuric chloride and potassium iodide are mixed, a double decomposition takes place, and the mercuric iodide separates as a yellow pre- cipitate, which immediately turns bright red. It is sparingly soluble in water, but freely soluble in solutions of KI and alcohol, forming clear solutions. It also dissolves in many dilute acids, and in solutions of ammonium salts, alkaline chlorides and mercuric salts. From its alcoholic solution it crystallizes MERCURY. 233 in bright red, rhombohedral crystals. When heated, it becomes yellow, fuses, and sublimes in yellow, shining, rhombic needles. These again become red upon touching them with some solid, and are changed into a mass of octahedra. Mercuric iodide is, therefore, dimorphous. 485. Mercuric Oxide—Red, or Binoxide—Hydrargyri Oxidum Flavum (U. S., Br.)—Hydrargyri Oxidum Ru- brum (U. S., Br.), (HgO), is obtained by igniting mercurous or mercuric nitrate as long as fumes are given off; or, by adding sodium hydrate to a solution of a mercuric salt. The product ob- tained by the first method is red and crystalline, of sp. gr. 11.2; that obtained by precipitation is yellow and amorphous, furnish- ing Hydrarg. oxid. flavum (U. S. P.). The latter is the more active form. Both modifications turn black when exposed to light and air. At 400° C. (752° F.) it breaks up into mercury and oxygen. Mercuric oxide is very sparingly soluble in water. It is the chief ingredient of the Lotio hydrargyri flava (Br.), or yellow wash, prepared by adding lime water to a solution of mercuric chloride. 486. Mercuric Nitrate (Hg(N03)2 may be obtained by dissolving mercury or mercuric oxide in hot nitric acid. This should be carefully conducted as it is inclined to form basic salts. It dissolves in water, and exists in the Liq. hydrargyri nitratis (U. S.), or Liq. hydrargyri nitratis acidus (Br.). It is used in the volumetric estimation of urea by Liebig’s method. The standard solution used for this purpose contains 71.48 grms. of metallic mercury to the litre, and 1 c.c. corresponds to 10 mgrms. of urea. 487. Mercuric Sulphate (HgS04) is prepared by warm- ing mercury or its oxide with an excess of sulphuric acid. With an excess of water, it decomposes into sulphuric acid and the yellow, insoluble, basic salt, Turpeth mineral, HgS04.2Hg0. It is a white, crystalline salt, used in some forms of galvanic bat- teries as the exciting agent. 488. Mercuric Sulphide—Red Sulphide—Cinnabar— Vermilion—Hydrargyri Sulphuretum Rubrum (U. S.), (HgS), occurs native in radiating or amorphous masses. It may be prepared by rubbing sulphur and mercury together, or by the precipitation of a mercuric salt by hydrogen sulphide, as a black amorphous mass, which is the i*Ethiops mineralis of the older pharmacists. 489. Medical Action of Mercury.—If introduced into the animal economy, metallic mercury is not poisonous. By 234 INORGANIC CHEMISTRY. contact with alkaline chlorides, however, it is converted into mercuric chloride; the more finely divided the particles of mercury are, the more readily does this take place. Mercuric chloride has a decidedly toxic action, both locally and constitutionally. Its local irritant action is due to its tendency to unite with albuminoid bodies. The constitutional symptoms are somewhat similar to those produced by arsenic, but appear sooner. The vomit frequently contains blood, and there is an intense burning, metallic taste in the mouth. The symp- toms that are referable to the gastro-intestinal mucous membrane are more intense. The size of the minimum fatal dose of the corrosive chloride is about three grains; of white precipitate, thirty to forty grains; and of Turpeth mineral, about forty grains. Children tolerate mercury much better, in proportion to their age, than adults. The treatment should consist in the administration of milk or white of egg, and the induction of prompt emesis. Absorbed mercury probably exists in the blood as an albuminate, and is eliminated by the faeces, urine and saliva; chiefly by the former. Chronic mercurial poisoning, known as mercurial tremors, shaking palsy, etc., is met with in those who work in mercury compounds. The symptoms usually begin with debility, nausea, vomiting, colicky pains, and a constant metallic taste in the mouth. Sooner or later salivation will become a prominent symptom, the tongue and gums becoming swollen, red and ulcerated, and the breath will emit a peculiar fetid odor. Sali- vation may, however, be produced by bromine, antimony, lead, prussic acid, etc. Chronic and even acute poisoning may occur from the free ex- ternal use of mercuric salts. Post-mortem the mucous mem- brane of the stomach is usually found of a grayish color, as also that of parts of the mouth and oesophagus. The surface of the mem- brane is sometimes covered with a slate-colored deposit of finely divided mercury. Tests.—One of the simplest tests for mercury in solution is a piece of bright copper, which, in the presence of a small quan- tity of free hydrochloric acid, becomes coated with a silver white layer of copper amalgam. All salts of mercury are volatile. When heated in a tube with sodium carbonate, globules of metallic mercury distill off from all salts. Mercury salts give a black precipitate with H2S, which is insoluble in nitric acid, but soluble in aqua regia. SILVER. 235 SILVER. Argentum, Ag — 108. 490. Occurrence.—This metal occurs in nature in combi- nation with chlorine, bromine, iodine, sulphur, arsenic, copper, antimony, etc. The principal localities in which it is found are the western United States, Mexico, Hungary and Saxony. 491. Preparation.—For an elaborate description of the pro- cess by which silver is extracted from its ores, the student is referred to works on metallurgy. As usually obtained by these processes the metal is not pure, but is contaminated to a greater or less extent by copper and other metals. To obtain it chemically pure, the ordinarily occurring silver is dissolved in nitric acid, and from this solution of the nitrates, silver is pre- cipitated as chloride by hydrochloric acid or common salt. The silver chloride thus obtained may be reduced by fusion with sodium carbonate, or by the action of zinc or iron in the presence of water. 2AgCl + Zn = ZnCl2 + 2Ag. 492. Properties.—A brilliant white metal; sp. gr. 10.47 to 10.54. It is tolerably malleable, soft, very ductile, and is the best conductor of heat and electricity known. It does not oxidize in the air, but frequently tarnishes in ordinary atmos- pheres, from the presence of minute quantities of hydrogen sulphide, which blackens it. With the members of the halogen group it unites directly. It dissolves in hot, strong sulphuric acid, to form the sulphate, but is more easily attacked by nitric acid, which dissolves it with great readiness, even when largely diluted. In order to give it the necessary hardness for use in the arts, it is usually alloyed with copper. Coin silver contains 10 per cent, of copper. 493. Silver Oxide—Silver Monoxide—Silver Protox- ide—Argenti Oxidum (U. S., Br.), (Ag20), is precipitated from solutions of soluble silver salts by sodium or potassium hydrate, as a dark brown, faintly alkaline powder, slightly soluble in water. It has strong basic properties. It readily gives up its oxygen when heated. When it is dissolved in ammonium hydrate there separate, on evaporating, black crystals of an explosive compound (Ag20.2NH3), which, when dry, explode on the slightest disturbance. Silver Suboxide (Ag40) and Silver Peroxide (AgO, or Ag202) are also known. 236 INORGANIC CHEMISTRY. 494. Silver Chloride (AgCl) forms whenever hydrochloric acid or a soluble chloride is added to aqueous solutions of silver salts, as a curdy white precipitate. It is insoluble in acids, soluble in solutions of alkaline chlorides, hyposulphites and cyanides, and freely so in ammonium hydrate. It may be crystallized from ammoriiacal solutions in large regular octahedra. 495. Silver Bromide (AgBr) precipitates from solutions of silver salts on the addition of hydrobromic acid or a soluble bromide. With the exception of not being quite so soluble in ammonium hydrate, it very closely resembles silver chloride. 496. Silver Iodide (Agl) differs from the chloride and bro- mide in its yellow color and insolubility in ammonia. Actinic rays of light change the color of silver chloride, bromide and iodide, first to violet, then brown, and finally black. The bro- mides and iodides are more sensitive to light than the chloride. 497. Silver Nitrate—Argenti Nitras (U. S., Br.), (AgN03), is prepared by dissolving pure silver in somewhat dilute nitric acid, evaporating, re-crystallizing, and washing with strong nitric acid. It separates in large anhydrous plates, soluble at ordinary temperatures in one part of water or four parts of alcohol and forming colorless solutions. In the presence of organic matter its solutions turn black, and deposit metallic silver on exposure to light.' It has been proposed to use this salt as a test for organic matters in potable waters. When fused and cast into cylindrical moulds, it forms the Argenti nitras fusa(U. S. P.), lapis infernalis, or lunar caustic of pharmacy. Chlorine and iodine decompose it with liberation of anhydrous nitric acid, and the formation of a chloride or iodide. This salt is also used in photography, in the manufacture of hair-dyes, marking ink, and in the silvering of glass. 498. Silver Cyanide—Argenti Cyanidum (U. S. P.), (Ag CN), precipitates from silver nitrate solutions as a white, curdy mass, by the addition of potassium or sodium cyanide. It is freely soluble in an excess of the reagent. It is also soluble in ammonium hydrate and sodium hyposulphite, but is not affected by light. A solution of this compound in potassium cyanide is used as the plating bath in electro-plating. 499. Silver Salts in Photography.—The property of undergoing reduction to the metallic state by the action of light and organic matter, makes the silver salts useful in photography. In taking a photograph, a negative is first prepared, as follows: A plate of glass, previously well cleaned, is evenly covered by GOLD. 237 floating over it a solution of collodion (a solution of pyroxyline in ether and alcohol) containing a small quantity of iodide or bromide of potassium, and then dried. On dipping the plate into a solution of silver nitrate, it becomes coated with a layer of silver iodide or bromide. After exposure in the camera it is taken to the dark room and “ developed ” by pouring upon it a solution of pyrogallic acid, or ferrous sulphate, which reduces the silver salts to the metallic state on that portion of the plate that has been acted upon by light, and makes it opaque. In printing from this, a paper previously wetted by floating it upon a solution of silver nitrate, is placed behind the negative and exposed to a strong light. The same action takes place upon the paper; the lights upon the negative becoming dark upon the paper. The image is fixed by dissolving off the undecomposed silver with a solution of sodium hyposulphite. GOLD. Au = 197. 500. This is the only member of the group. It is sometimes classified as one of the precious metals. 501. Occurrence.—Gold occurs native in wide distribution, though in small quantities. Generally found in veins of quartz, from which it is extracted, after pulverization, by dissolving it out with mercury. The amalgam thus formed is subjected to heavy pressure, which squeezes out the excess of mercury, the rest being separated by distillation. 502. Properties.—Gold is orange yellow by reflected light, and green by transmitted light; very ductile and exceedingly malleable. It fuses at 1200° C. (2192° F.); has a specific gravity of 19.36, and is a good conductor of heat and electricity. It retains its lustre even at high temperatures. It is not affected by any single acid or alkaline hydrate. A mixture of nitric and hydrochloric acids readily dissolves it, forming a solution of the chloride. It combines directly with the halogens, phospho- rus, antimony, arsenic and mercury. In handling bromine, care should be taken that its vapor, or the bromine itself, does not come in contact with rings or other gold jewelry, lest they be attacked. 503. Uses.—Neither gold nor its preparations are much used in medicine. It is extensively employed, however, in the manu- facture of jewelry and for coinage. For either of these purposes it is too soft to be used alone, but is always alloyed with either copper or silver. In estimating the fineness of gold in jewelry, 238 INORGANIC CHEMISTRY. it is divided into twenty-four equal parts, called carats. The alloy is said to be of so many carats fineness, according to the number of twenty-fourths of pure metal that it contains. Eighteen-carat gold is, then, If gold, and six carats base metal. 504. Aurous Oxide (Au20) is a dark violet powder, formed by the action of potassium hydrate upon aurous chloride. Hydro- chloric acid changes it to auric chloride and gold. 505. Auric Oxide (Au203) is prepared by digesting magnesia in a solution of auric chloride, decomposing the magnesium aurate by nitric acid, and drying the residue at 100° C. (212° F.). It is a dark brown powder, which decomposes easily, and unites readily with positive oxides to form aurates having the gen- eral formula RAu02. It will thus be seen, from its behavior with oxygen, that gold in its valence is either monad or triad. 506. Aurous Chloride (AuCl) is a pale yellow, insoluble powder, formed by heating auric chloride to 200° C. (392° F.). Auri et Sodii Chloridum (AuCl3NaCl) is used in medicine. It is a yellow, deliquescent solid, having a saline, metallic taste and acid reaction. It is soluble in water and alcohol 507. Auric Chloride—Gold Trichloride—(AuC13), occurs in deliquescent prisms, soluble in water, alcohol and ether. With phosphorus or reducing agents it is readily decomposed, with separation of gold. When in solution, it gives, with stannous chloride, a beautiful purple, flocculent precipitate—purple of Cassius—which is used to ornament glass and porcelain. ALUMINIUM GROUP. Glucinium, Gl —13.8 Aluminium, Al = 27.5 Gallium, Ga = 69.9 Indium, In = 113.4 Aluminium is the only member of this group that is of importance. ALUMINIUM. A1 = 27.5. 508. This metal is found very widely distributed. It exists as oxide in ruby, sapphire and corundum, and, less pure, as emery. Most commonly it occurs as the silicate (clay, kaolin), and with other silicates, as feldspar, mica, and in most crys- talline rocks. 509. Preparation and Properties.—Aluminium may be obtained in the metallic condition by igniting the chloride, or, ALUMINIUM. 239 better, the double chloride of sodium and aluminium with sodium. Al2Cl6.2NaCl -f 3Na = Al2 + 8NaCl. It is a silver-white metal, very malleable and ductile, a good conductor of electricity ; sp. gr. 2.56. At ordinary temperatures it is not affected by air or oxygen, but burns if heated in oxygen. It is insoluble in nitric acid, soluble in boiling sulphuric and cold hydrochloric acids. It dissolves in alkaline hydrates to form aluminates, with liberation of hydrogen. It forms a very hard and durable alloy with copper, known as aluminium bronze. 510. Aluminium Oxide—Aluminia (A1203), is found crystallized in prisms, and colored by other admixtures, in ruby, sapphire, corundum and topaz. These minerals are all exceedingly hard, ranking next to the diamond in this respect. Aluminia may be obtained artificially by igniting the hydrate, as a light, white, insoluble, odorless and tasteless powder. Acids attack it with great difficulty when prepared as above. It may be decomposed by fusing with caustic alkalies or acid po- tassium sulphate. 511. Aluminium Hydrate (Al2(OH)6) is formed by pre- cipitating a solution of an aluminium salt with ammonium hydrate or carbonate. When freshly precipitated it is insoluble in water, but soluble in solutions of the fixed alkalies. By pro- longed drying, or after standing under water, it is rendered almost insoluble in acids, although it undergoes no change in composition or appearance. 512. Aluminium Chloride (A12C16) is obtained by the action of chlorine upon heated aluminium. It forms color- less hexagonal prisms; fusible, volatile, and very soluble in water and alcohol. It crystallizes from a hot concentrated solu- tion with 12H20. 513. Aluminium Sulphate (A12(S04)3) is prepared arti- ficially by the action of sulphuric acid upon kaolin or clay. Also, by dissolving aluminium hydrate in the same acid (alumi- nii sulphas, U. S.). It crystallizes in thin plates with 18H20 ; soluble in water, and sparingly so in alcohol. When heated, it fuses and becomes anhydrous. 514. Alums.—These are double salts formed by the combina- tion of aluminium sulphate with the alkaline sulphates. The salt originally known as alum is the double sulphate of alumin- ium and potassium, (K2A12(S04)4.24H20). It is obtained from clays free from iron, and from aluminite, a basic sulphate of 240 INORGANIC CHEMISTRY. aluminium. The potassium in this alum can be replaced by sodium, ammonium, rubidium, caesium and thallium. Potas- sium alum forms large, regular, transparent, octahedral crys- tals, soluble in water. Heated to about redness, it loses 45 per cent, of its weight of water, forming the product known as burnt alum. Aluminium and ammonium sulphate, or ammonia alum, A12(S04)3,(NH4)2S04.24H20, is rapidly taking the place of the potassium alum, from which it differs in being more soluble in water between 20°C. (68°F.) and 90°C. (194°F.), and less soluble in water colder or warmer than this. At about the temperature at which potash alum loses its water, ammonia alum decomposes and loses its ammonia. Ferric iron, manganese and chromium may replace the aluminium in alum, and form a series of alums known as ferric alum (see Art. 438), manganese alum and chrome alum. THE PLATINUM METALS Platinum, Pt = 198. Rhodium, Rh = 104. Palladium, Pd = 106.5 Ruthinium, Ru = 104. Iridium, Ir = 197.2 515. These five elements are usually classed as “ metals of the platinum ores,” or the platinum group of metals. The platinum ore, or crude alloy, occurs in small metallic grains in sands of a few regions, chiefly in the Ural mountains, Brazil and Ceylon. These metals all form hydrates (or salts represent- ing them) having acid properties, and therefore play both the positive and negative role. Platinum is the only one used to any extent in the metallic condition. PLATINUM. 516. Occurrence, Properties, etc.—It exists in nature associated with the other members of the group; also, in ores con- taining gold, lead, silver and iron. It is a lustrous, white metal; sp. gr. 21.5. It is very tenacious, malleable, ductile, and is capable of being drawn out into very fine wire. At high temperatures it softens without melting; it fuses at about 1770°C. (3218°F.). Upon heating the double chloride of platinum and ammonium, a grayish-black, spongy mass forms, called platinum sponge. This latter has the property of absorbing great quantities of certain gases. A jet of hydrogen projected upon it readily inflames by the oxidation Pt = 198. MOLYBDENUM GROUP. 241 of the hydrogen in the pores of the sponge, the heat developed being sufficient to inflame the hydrogen. Platinum is not affected by the air or oxygen. It unites with chlorine, arsenic, silicon, sulphur and phosphorus. It does not dissolve in acids, and is only soluble in liquids generating free chlorine, as aqua regia. With many heavy metals it forms easily fusible alloys. Therefore, easily reducible metallic oxides, as of arsenic, lead, etc., ought never to be ignited in platinum vessels. Platinum is valuable for its high fusing point and its power to withstand oxidation ; and is expensive, because of its scarcity. 517. Platinum Compounds.—These are of two series, platinous, PtR2, and platinic, PtR4. In the first, the metal is more basic, and in the latter, more acid in nature. Platinic Tetrachloride (PtCl4) is obtained by dissolving platinum in aqua regia and evaporating off the nitric acid. On evaporating, it crystallizes in soluble, reddish-yellow needles. With ammonium or potassium chloride and the alkaloids, it forms characteristic double chlorides. This salt is largely used to precipitate potassium, ammonium, or the alkaloids, for quanti- tative estimation. Molybdenum, Mo=96. Tungsten (Wolfram), W=-184. Osmium, Os = 198. MOLYBDENUM GROUP. 518. These elements are of little importance themselves; their oxides, however, and some of their compounds are some- times used. 519. Molybdic Trioxide or Anhydride (MoOs).—This oxide is obtained by roasting the native sulphide in an open vessel, at a red heat. The principal interest attached to it is its use in preparing ammonium molybdate, a reagent used to detect and estimate phosphoric acid. The impure oxide obtained by roasting the mineral molyb- denite, MoS2, is dissolved in ammonium hydrate, evaporated to dryness, re-dissolved in water, concentrated by evaporation, and allowed to crystallize. The soluble molybdates give a precipitate of Mo03 on the addition of acid ; but it is soluble in excess of acid. The molybdates give a white precipitate with the earthy metals. With phosphoric acid or the phosphates, a solution of ammonium molybdate containing an excess of nitric or hydrochloric acid first turns yellow, then deposits a yellow pre- cipitate of molybdic trioxide, phosphoric acid and ammonia, 242 INORGANIC CHEMISTRY. which is very soluble in ammonia water. This is a very delicate test for phosphoric acid; pyrophosphates and metaphosphates do not give the reaction. Arsenic acid gives a similar pre- cipitate. 520. Tungstic Acid (EL\V04) is a yellowish-white powder thrown down from boiling alkaline solutions of tungstic oxide by mineral acids. It forms with bases numerous salts, called tungstates, the most important of which is sodium tungstate (Na2W04.2H20). This has recently attained considerable im- portance as a test for albumen in urine, and from its property of rendering fabrics dipped in solutions of it non-inflammable. OSMIUM. 521. This unusual metal, occurring with some of the other platinum metals, is mentioned here for the sake of its oxide (0s04), which has received considerable attention as a staining agent. The metal resembles platinum. The tetroxide (0s04) (so-called osmic acid), may be pre- pared by glowing the metal in air, or by the action of chlorine and moisture upon osmium. This oxide has a very irritating, piercing odor, and is intensely poisonous. It has been used to arrest the motions or to kill the organisms in water, for micro- scopical examination. Many kinds of organic substances reduce this oxide and pre- cipitate the metal, and it is due to this property that it has found use as a staining agent in histology, to bring out delicate structures. Os = 198. PART IV. ORGANIC CHEMISTRY. 522. Carbon and Hydrogen.—The substances derived from the animal and vegetable kingdoms are composed principally of four elements: carbon, hydrogen, oxygen and nitrogen, with occasionally sulphur and phosphorus. Few as are the chem- ical elements concerned, the number of different compounds of these elements is almost endless. Formerly only those sub- stances directly or indirectly derived from bodies possessing vegetable or animal life were considered as organic; but as our knowledge increased, a large number of compounds were pre- pared in the laboratory from these bodies, which were identical with others prepared from the elements themselves. It was thus demonstrated that by pure chemical agencies many of the pro- ducts of living organisms could be prepared, and that a vital principle was not necessary to form these compounds; and, also, that by the same chemical action a great many compounds could be formed which could not be found in either animal or vege- table organisms. Some artificial bodies were afterwards found to exist in either animal or vegetable organisms. This greatly enlarged the field of investigation, and a new meaning was attached to the term organic chemistry; it was found neces- sary to extend the science to include all bodies in any way resembling organic compounds, either in composition or proper- ties ; i. e., all compounds containing carbon and hydrogen. Car- bon and hydrogen are the indispensable elements to the formation of organic bodies; without these we can have no substance capable of vegetable or animal life. In the great majority of organic compounds we also have oxygen or nitrogen, or both. 523. Organic Chemistry may be defined as that branch of the science of chemistry which treats of the carbon compounds containing hydrogen, either alone, or with oxygen, nitrogen, sul- phur, phosphorus, etc. While inorganic compounds, as a rule, contain but a few atoms, organic compounds frequently contain a large number; and the diversity in organic chemistry is obtained not by varying the 243 244 ORGANIC CHEMISTRY. kind of atoms, but by varying the arrangement of a few kinds. There exist, however, certain organized bodies which possess a structure entirely different from that of any known inorganic body or artificial organic substance. These organized structures are the sole product of vital action, and cannot be produced in the laboratory. Such bodies are seen in the cell of living organ- isms ; and although we may be able at some time to construct molecules identical with those composing them, we shall never be able to impart that function of growth, reproduction, and other vital processes which we call life. The complexity of organic compounds may readily be attributed to the inherent properties of carbon, the leading or most characteristic element of which they are composed. The atoms of carbon exhibit, in a remark- able degree, a tendency to combine themselves into groups or chains, around which the other atoms or groups of atoms are arranged. In other words, the carbon atoms are the skeleton in and upon which a very complex structure may be built. The underlying principle of organic chemistry is the grouping of the carbon atoms, and upon these groups the whole superstructure is based. 524. Carbon Nuclei.—Carbon is a tetrad and can com- bine with four monads. As has been said, it can also unite with another carbon atom, and the two atoms thus united will com- bine with six monad or hydrogen atoms: H\ /B. H—C — C—H H/ \H Three, four, five, or any number (n) atoms of carbon may thus unite, theoretically at least, and give rise to a chain of atoms, which has been called an open chain. Again, the same atoms II /c\ =c c= I I =c c= \ .hence for cleiin' A NaPbtha 148'8° C- (300° *> J L SoStd ‘‘safety oil.” Benzene 148° to 160° C. (298° to 320° F.) For varnishes and paints. Kerosene, or Refined Petroleum 176° C. (349° F.) For ordinary lamps. Mineral Sperm Oil... 218° C. (424° F.) Lubricating Oil 301° C. (574° F.) Lubricating machinery . Paraffine Solid. For candles. The vapors of all the lighter products when combined with air form explosive mixtures, and hence, laws exist in most countries prescribing the lowest temperature at which kerosene shall give an inflammable vapor, or at which it shall “ flash.” The law of the State of New York declares that oils used for illuminating purposes shall not give a vapor that will “ flash ” below 100° F., and shall not themselves ignite below a temperature of 300° F. Fossil resins, bitumen, ozocerite (animal wax), all belong to this group of hydrocarbons. 528. The Olefines, or CuH2n Series.—The olefines differ from the paraffines in being unsaturated compounds. The first member of the series, ethylene, C2H*, combines directly with chlorine, forming a thick, oily liquid, from which the discoverers named it olefiant (oil making) gas. The iodide and bromide may also be formed by direct union. The olefines combine with the hydracids. CaH4 + HC1 = C2H6C1. Ethylene (olefiant gas), C2H4, is found in illuminating gas, the CARBON AND HYDROGEN. 249 illuminating power of which depends largely upon its presence. It is a colorless gas, of a peculiar, pungent odor, and is soluble in strong H2S04, with which it combines. It burns in the air with a bright, luminous flame. Its sp. gr. is .9785 ; density, 14. The higher members are unimportant; of these butylene, c4h8, is liquid or solid at ordinary temperatures. 529. Acetylenes, CnH2n_2 Series.—This series of hydro- carbons fall short of saturation by four monad atoms, and can, therefore, act as dyad or tetrad radicals. Acetylene, C2H2, com- bines directly with either two or four atoms of chlorine, bromine or iodine. Nascent hydrogen converts it into ethylene, C2H4, and oxidizing agents (potassium permanganate, etc.) into oxalic acid. Acetylene is formed whenever kerosene or coal gas is incompletely burned, and gives the disagreeable odor detected in a room when the lamp is turned low. It exists in coal gas, and possesses a high illuminating power. 530. Fourth Series.—General Formula, CQH2a_4. This series of hydrocarbons includes turpentine and a large number of other so-called essential, or volatile oils. These oils are mostly isomers or polymers, having the formula C10H16, or a multiple of this. Turpentine is extracted from several varieties of the conifera family, notably the pine. When turpentine is distilled, the hydrocarbons volatilize, while resin remains behind. Oil of tur- pentine is a mobile, colorless liquid, with a sp. gr. of 0.89, and boils at 160° C. (320° F.). It is almost insoluble in water, but dissolves in alcohol, ether, and glacial acetic acid. It dissolves sulphur, resin and phosphorus. It absorbs oxygen from the air and becomes oxidized, forming a resinous body. The absorbed oxygen is converted into ozone, and this explains its oxidizing, disinfectant and antiseptic action. As the oxidation of turpentine takes place more rapidly when mixed with lead oxide, this oxide is often intermixed with the turpentine in paints, to increase the rapidity of drying. It attacks lead rapidly, but not tin. A paper dipped in turpentine and introduced into a jar of chlorine gas inflames spontaneously, forming substitution pro- ducts. Iodine and bromine have a similar action upon it. It unites directly with HC1, producing several hydrochlorides. Oil of Lemon, obtained from the peel of the common lemon, Citrus Limonum, oil of orange peel, cloves, juniper, pepper, elemi, lavender and bergamot, belong to the same class, having the formula C1(,Hlfi. All the essential oils, hoAvever, do not belong to this series of hydrocarbons. Oils of copaiva and 250 ORGANIC CHEMISTRY. cubebs have the formula C20H32, while caoutchouc and gutta- percha are higher polymers of the above. The principal characteristics of these essential oils are their odors, variations in the rapidity of oxidation, reaction with hydrochloric acid, and physical properties. They are soluble in alcohol, ether, benzole, petroleum, naphtha, chloroform, carbon pisulphide, paraffine, and other volatile oils, and in the fixed oils. They may be separated from their alcoholic solution by adding water, or a solution of sodium sulphate. They are not saponified by alkalies. 531. Caoutchouc, or India Rubber, is the dried milky juice of several tropical trees. The fresh juice is acid. It is a mixture of several hydrocarbons which are insoluble in alcohol and water, but soluble in sulphuric ether, benzole, chloroform, carbon disulphide and turpentine. When cold, it is hard and tough, but on heating, it becomes soft, elastic, and finally melts, and on cooling, remains soft and viscid. It is much used in making elastic, water-proof fabrics, elastic tubing, etc., and is acted upon by but few reagents. The black color of the com- mercial article is due to smoke and partial decomposition. Caoutchouc combines with sulphur. Vulcanized India- rubber is obtained by mixing it intimately with sulphur, by the aid of carbon disulphide, to the extent of two or three per cent., and afterward heating. Common white rubber goods, as rubber tubing, etc., are also mixed with oxide of zinc and other impuri- ties to a very large extent, in some cases but a few per cent, of rubber being used. When mixed with about half its weight of sulphur, a hard, horny mass, called Vulcanite, or Ebonite, is produced, which is used in the manufacture of combs, cheap jewelry, etc. When heated, caoutchouc decomposes, but does not volatilize. Gutta-percha is the hardened, milky juice of Isonandra Gutta, a tree growing in some parts of India. It resembles caoutchouc, but is harder and less elastic. In hot water, it becomes quite soft and can be moulded into any shape, which it retains on cooling. With solvents and high temperatures, it behaves like caoutchouc. 532. Common Camphor, Ci0H1BO, is obtained in China and Japan by distilling the branches and leaves of Laurus Camphora with water. It is a white, translucent, crystalline mass, having a powerful, peculiar, pungent odor and taste. It is readily CAMPHORS. CAMPHORS. 251 purified by sublimation at 205° C. (401° F.). It melts at 175° C. (347° F.) and burns with a smoky flame. Camphor is very slightly soluble in water, but readily soluble in alcohol, ether, acetic acid, benzole, chloroform, carbon disulphide, fixed and essential oils. Aqua Camphorae and Tinctura Camphorae are officinal, and it enters into the composition of Linimen- tum Camphorae, Liniment. Saponis, Tinctura Opii Camphorata. Camphor forms a large number of decomposition products and derivatives under the action of reagents, but we shall notice but one of these. Monobromo-camphor—Camphora Monobromata (U. S. P.), C10H15BrO, is prepared by adding bromine to a solution of camphor in chloroform, by which camphor dibromide is obtained. This compound is unstable, and on standing, sets free hydro- bromic acid and forms monobromated camphor, which crystal- lizes in colorless, prismatic needles or scales, permanent in the air, having a mild camphoraceous odor and taste, and neutral reaction. Its solvents are essentially the same as those of camphor. It melts at 65° C. (149° F.), boils at 274° C. (525° F.), and is volatilized with partial decomposition. In medicine it is used as a sedative. Eucalyptol, Ci2H20O, is a colorless liquid, boiling at 175° C. (347° F.), and possessing an aromatic odor. It is contained in the leaves of the Eucalyptus Globulus, a tree growing in Tasmania. On account of its supposed effect upon miasmatic atmospheres, it has been cultivated in southern Europe, the United States and northern Africa. By distilling it with phosphorus pentachloride, PC15, eucalyptine, C12H18 (by some C10HI8), is obtained. Eucalyptol is slightly soluble in water, but soluble in alcohol. The oil has feeble antiseptic properties and has been used in bronchitis, cystitis, and in intermittent fevers. Menthol,* or Menthyl Alcohol, Ci0H2oO, is a white, solid, crystalline body occurring in oil of peppermint, and possessing a strong odor of this plant. It melts at 36° C. (96.8° F.) and boils at 210° C. (410° F.) Menthol is soluble in alcohol and the essential oils. * Although really an alcohol, it is classed here with the camphors, owing to physical properties. 252 ORGANIC CHEMISTRY. RESINS, OLEO-RESINS, GUMS, BALSAMS. 533. Many of the bodies of the turpentine and essential oil series above mentioned, when exposed to the air, undergo a process of oxidation or hardening, become viscid or solid, and exhibit an acid reaction. Such bodies, when brittle and solid, are called resins ; when composed of unoxidized oils mixed with resins, they are called balsams ; when the resins exist in the juices of plants mixed with gum, sugar, etc., they are called gum-resins. Each one of these bodies is generally a mixture of several bodies, and, therefore, no definite chemical formula can be given. They are insoluble in water, but soluble in strong alcohol, turpentine and glycerine ; many are soluble in ether and benzole (separa- tion from gums) ; many are weak acids, whose alkaline salts form the resin soaps of the market. Many resins are used in medicine, in the manufacture of varnishes, sealing wax and salves. The resins soften when heated, but do not vaporize. The separation of resins from volatile oils and acids, is effected by distillation with water; from gums, by fusion and straining at 100°C. (2h2°F.) ; and from each other, as well as from foreign substances, by properly selected solvents. Only the most important resins can be described. Common resin, or colophony, is the residue left by distilling the balsam of the pine with water. Turpentine passes over, and leaves a brown, brittle, shining mass, which, when melted, forms common resin. It is soluble in alcohol, ether and oils. Copal is a yellowish or brown resin, obtained from various trees of the East and West Indies and Africa, and is used in preparing varnishes. Amber is a yellowish, hard, brittle, more or less transparent solid, found on the shores of the Baltic, and called fossil resin. Ammoniacum contains 72 per cent, resin, 22 percent, gum, and a little volatile oil. Benzoin contains 75 per cent, resin, 10 to 15 per cent, of benzoic acid, a little gum and volatile oil. Balsam Copaibse consists of several resins and a volatile oil. Guaiacum is a brittle, pulverizable solid, of a reddish-brown color. The gum dissolves in alcohol. It readily undergoes oxidation, producing bright colors. A mixture of the officinal tincture and oil of turpentine is frequently employed as a reagent for detecting blood in urine, with which it strikes a blue color NAPHTHALENE AND ANTHRACENE. 253 Gum Lac, or Shell Lac, is an exudate from several East Indian trees, caused by punctures of insects. It contains about 90 per cent resin, and a coloring matter soluble in water. It is soluble in alcohol, this solution being used as a varnish. Among the balsams, storax, tolu, and balsam of Peru may be mentioned. Among the gum resins, the following are most important: Ammoniac (see above), galbanum, gamboge, myrrh and asafoetida. BENZOL OR AROMATIC SERIES. 534. One member of this series is of considerable importance: viz., Benzol, or benzene. This compound, C6HB, must not be confounded with benzene, which is a trade name, and is used to designate a mixture of hydrocarbons having a variable com- position and boiling point. Benzol was formerly prepared by distilling benzoic acid with lime. At present it is obtained in large quantities by the distillation of coal tar from gas works. Benzol is a colorless, limpid, highly refractive liquid, with a pe- culiar odor and burning taste. It burns with a smoky flame, and is insoluble in water, but soluble in alcohol, ether and naphtha. It dissolves sulphur, phosphorus, iodine, resins and fats. Benzol, with its homologue, Toluene C7H8, is very interesting to the chemist, because they serve as the starting point in the synthesis of a large number of coloring matters known as aniline colors. CnH*2n—6. NAPHTHALENE AND ANTHRACENE. 535. Naphthalene, Ci0H8, is obtained from coal tar by distil- lation between 180°C. and 220°C. It comes over with heavy oils, but crystallizes from them in white, glistening, leafy crystals, of a peculiar, aromatic odor and burning taste; it melts at 79.2°C. (174.5°F.), is insoluble in water, but soluble in hot alcohol, ether or benzene. The principal interest of naphthalene to the physician is its value as an antiseptic dressing for wounds. For this purpose it must be thoroughly purified by recrystallization from alcohol, or by distillation with steam. Anthracene, CUH10, is a white, crystalline body obtained from coal tar, distilling above 360°C. (680°F.). It is of great interest to the chemist, being the starting point in the manufacture of alizarine, or artificial madder. Its solu- 254 ORGANIC CHEMISTRY. tions possess a beautiful blue fluorescence, a property observed in many of the heavier hydrocarbons derived from coal tar and petroleum; i. e., their solutions are colorless or yellowish by transmitted light, but when viewed by reflected light, appear bluish. The phenomenon is well seen in solutions of quinine sulphate. 536. Addition Products are readily formed from unsatu- rated hydrocarbons like the olefines or acetylenes. One mole- cule of the hydrocarbon always unites with two or four atoms or radicals added. It is especially the atoms of the chlorine group, or their hydracids, which are thus added; but hydrogen, as well as other hydrocarbon radicals, may also be added. C2H4 + Cl2 = C2H4Cl2. Ethylene. Ethylene chloride. C2H4 + HC1 = C2H5C1. Ethyl chloride. C2H4 + H0C1 = C2H4 | Ethylene chlorohydrine. 537. Substitution Products.—One or more of the hydro- gen atoms of the various hydrocarbons may be made to exchange places with either simple or compound radicals. Indeed, we might regard all the complex organic bodies as made up in this way. Thus, ethane, C2H6, may be regarded as a molecule of methane, CH4, in which one hydrogen atom has been replaced with the radical CH3. Thus : /H /CH3 C—H + CH3 = C—H + H2. X>h \\H \h \h The limits of this work will not permit qs to enter into the various reactions by which all these substitutions are brought about; the student is referred to special works on organic chem- istry for these reactions. 538. Organic Radicals.—In organic chemistry, as in inor- ganic, although to a greater extent, we are constantly dealing with certain well defined groups of atoms, which retain their identity through a large series of compounds and behave in chemical reactions like simple radicals or atoms. It is evident that by removing one or more atoms of hydrogen from any saturated hydrocarbon, the remaining group of atoms may act as a compound radical; while the unsaturated hydro- NAPHTHALENE AND ANTHRACENE. 255 carbons of the acetylene or olefine series may act as radicals without the removal of any hydrogen atoms. These hydrocarbon radicals are usually designated by the ter- mination yl. Thus: CH:j is known as methyl; C2H5, as ethyl; C6Hr„ as phenyl. These radicals are called, collectively, hydro- carbon or alcohol radicals, and the quality of their combining power is feebly electro-positive. 539. Synthesis of Organic Compounds.—The principal interest of chemists in recent years in the department of organic chemistry, is centred upon the synthesis of organic compounds. By these synthetical methods the chemist imitates, to a limited extent, the processes of animal and vegetable organisms. The natural tendency of all organic compounds is to break up com- plex molecules and form simpler ones, while it is the aim of synthetical methods to reverse this process and build up complex molecules from simpler radicals, adding little by little until the structure is complete. It is principally from synthetical reactions that we can arrive at a knowledge of the structure of complex organic bodies. With these synthetic methods, chemists have achieved great success in the artificial production of alizarine (the coloring matter of madder), indigo, salicylic acid and the great variety of aniline colors, which stand among the greatest achievements of modern science. Although we have not space to dwell upon the subject here, we introduce a few reactions from Cook's Chemical Philosophy, which will give the student an idea of the succession of steps by which these ends are attained. From the elements, by passing the vapors of sulphur over heated carbon, we obtain CS2. From H2S -J- CS2 passed over heated copper, we obtain CuS -f- CH4. The electric arc passed between carbon poles in an atmos- phere of hydrogen yields acetylene, C2 -f- H2 = C2H2. C2H2 -f nascent hydrogen = C2H4. C2H4 -f HBr = C2H5Br. Ethylene. Hydrobromic Acid. Ethyl bromide C2H5Br -f- nascent hydrogen = C2H6 + HBr. Ethane. 2C2H,I + (CH3)2Zn =- 2C2H5CH3 + Znl2. Ethyl Iodide. C3H7I + KOH = C3H6 + KI + H30. Zinc Methyl. Propane. Zinc Iodide. Propyl Iodide. Potassium Hydrate. Propene. C,H4Br2 + 2KOH = C2H2 + 2KBr + 2H20. Ethylene Bromide. Acetylene. 256 ORGANIC CHEMISTRY. These reactions will suffice to show the methods of converting the hydrocarbons from one homologous series to another, or from a lower to a higher member in the same series. 540. Alcohols. As shown in Article 319, the hydroxyl group (—OH) may be substituted for one atom of hydrogen in any satu- rated hydrocarbon. The resulting compound is called an alcohol. An alcohol may also be looked upon as one or more molecules of water in which one of the two atoms of hydrogen has been replaced by a hydrocarbon radical, and they are all referable to the water type. H—0—H, CH,—0-H, C2H5—0—H, C4H9—0—H. Water. Methyl Alcohol. Ethyl Alcohol. Butyl Alcohol. If we replace two atoms of hydrogen which are not united to the same carbon atoms, by the radical HO, we form what is known as a diatomic alcohol, or glycol. Thus, If three atoms of hydrogen united to three different carbon atoms be replaced by HO, a triatomic alcohol, or glycerine is produced. Thus— CH3—CH3 gives HO—CH2—CH2—OH. CH3—CH2—CH3 !?ives HO—CH2—CH—CH2—0—H. O I II Tetratomic, pcntatomic and hexatomic alcohols are known. 541. Ethers.—If, in a molecule of water, both the atoms of hydrogen be replaced by hydrocarbon radicals, an ether is pro- duced. When the two radicals are alike, the compound is a simple ether; when unlike, it is said to be a mixed ether. Examples of simple ethers— CII3—0-CH3. Methylic ether or methylic oxide. c2hs-o—c2h5. Etliylic ether or ethylic oxide. Examples of mixed ether— CH3-0-C2H5. Methyl-ethylic ether. Haloid ethers, so-called, are the addition or substitution products containing one of the halogen elements; as,— Compound ethers are formed by replacing one of the hydrogen atoms in a molecule of water by a hydrocarbon radical, and the other by an acid radical; as, C2H5Br or CH3C1. C2H5—0—C2H30. NAPHTHALENE AND ANTHRACENE. 257 542. Aldehydes.—This class of bodies are formed in the first stage of the oxidation of alcohols, and are intermediate be- tween alcohols and acids. They differ from the corresponding alcohols by having two atoms of hydrogen removed ; thus, ethyl alcohol, C2H5—O—H forms C2H3—O—H, ethyl, or acetic alde- hyde. Aldehydes by oxidation yield the corresponding acid. It will be observed that, as two atoms of hydrogen have been re- moved without putting any atoms in their places, aldehydes are unsaturated bodies. On this account, they are very liable to undergo changes with reagents. Hydrochloric and sulphuric acids and some other bodies convert acetic aldehyde, on stand- ing, into two isomeric bodies called paraldehyde and metalde- hyde. Ordinary aldehyde may be easily prepared by the slow or incomplete combustion of ether vapor. Heat a glass or iron rod and plunge it into a jar containing a little ether vapor, and the peculiar, pungent odor of aldehyde will be detected. Ordi- nary aldehyde is of little importance to the physician. Paraldehyde, C6H1203, or (C2H3OH)3, lias been introduced lately as a substitute for morphia. It is a liquid at ordinary temperatures, but forms a white, crystalline solid at 10° C. (50° F.); it is but slightly soluble in water. 543. Chloral is an aldehyde in which the three hydrogen atoms of the radical are replaced by chlorine atoms; thus: C2H3—O—H and C2C13—0—H. Chloral is prepared by passing dry chlorine into absolute alco- hol until saturated, and then adding sulphuric acid and distilling off the chloral. It is thus obtained as a colorless liquid, having a pungent irritating odor, and boiling at 94.5° C. (202° F.) It is a true aldehyde, which, by oxidation with nitric acid, gives trichlor-acetic acid, C2C1302H, a colorless, crystalline solid, which is soluble in water. This acid has been recommended as a test for albumen in urine. Chloral is converted into chloroform and a formate by the alkaline hydrates. C2C130H + NaOH = NaCH02 + CHC13. Chloral. Sodium Hydrate. Sodium Formate. Chloroform. It unites with water to form chloral hydrate, C2C130H.H20, a colorless, transparent, crystalline solid, having an aromatic, pungent odor and taste, and a neutral action on litmus paper. It is freely soluble in water, alcohol, ether, glycerine, benzine, fixed and volatile oils. When mixed with carbolic acid or camphor, it liquifies. It melts at about 58° C. (136.4° F.) and boils at about 95° C. (203° F.). It should be kept in glass 258 ORGANIC CHEMISTRY. stoppered bottles. Chloral hydrate is used in medicine under the name of chloral, to produce sleep. Its long continued use induces a chloral habit very difficult to cure. Bromal, C2Br3OH, is also known. 544. Ketones. These bodies are the result of the first action of oxidizing agents upon secondary alcohols; i. e., upon an alcohol which contains the group of atoms CHOH, instead of CH2OH, as in ordinary alcohol. By oxidation of these alcohols, the first result is to remove one atom of hydrogen, instead of two, as in the aldehydes. Acetone, (CH3)—CO—(CH:1), is the best known ketone. The corresponding secondary alcohol would have the formula CH3—CHOH—CH3. Secondary alcohols, when oxidized, yield ketones, while primary alcohols yield aldehydes. Ketones, by further oxidation, break up and yield two acids, while aldehydes yield one acid with the same number of carbon atoms. Acetone sometimes appears in the urine of diabetic patients, and is detected by the addition of ferric chloride, with which it gives a deep brown-red color. 545. Organic Acids.—The characteristic feature of an organic acid molecule, is that it must contain the group —COOH (car- boxyl), and the basicity of the acid will depend upon the number of these groups contained in its molecule. The organic acids partake of the general properties of the mineral acids. They may be referred to the water type and considered as one or more molecules of water, in which one atom of hydrogen has been replaced by an organic compound radical containing oxygen—a negative radical—while the other atom remains as replaceable, or basic hydrogen. As in inorganic acids, only those atoms of hydrogen which are linked to the carbon or negative group by oxygen are replaceable by a basic or metallic radical. Acids may be formed by the oxidation of an alcohol, an alde- hyde or a ketone. The presence of an alkali favors the forma- tion of acids. Acids maybe monobasic, dibasic, tribasic, etc., according as their molecules contain one, two, three, etc., carboxyl groups* (—COOH). Acids may also contain one or more hydroxyl groups, (OH), which are not basic, because not immediately attached to or associated with CO, to form the carboxyl group. The hydrogen of these hydroxyl groups is called alcoholic hydrogen to distinguish it from the other replaceable hydrogen, designated as basic. The number of hydroxyl groups in a molecule of either an alcohol or an acid is said to be its ALCOHOLS. 259 atomicity. It is evident that the atomicity of an acid may be greater than its basicity, when it is said to be an al cohol acid. Lactic acid, (H-O—COCH(OH)CH3 = (C3H40 j is a good example of a diatomic and monobasic acid. ALCOHOLS. 546. Having given a brief outline of the several groups of bodies which may be considered as derived from the hydrocar- bons, viz., alcohols, ethers, aldehydes, ketones and acids, we shall now proceed to notice briefly those members which may be considered of most importance to the student of medicine; and we shall omit many of the compounds which are of chemical interest only. Table of Monatomic Alcohols of the First Series, with corresponding Acids. Methyl Alcohol (Wood Spirit), CH3-0-H 66° C. Formic Acid, HCH02 100° C. + Ethyl “ (Spirit of Wine), C2H5—O-H 78.4° C. Acetic Acid, HC2H302 118° 0. Propyl “ C3H7-0-H 97 ° 0. Propionic Acid, HC3H502 141° C. Butyl “ C4H9-0-H 116 0 C. Butyric Acid, HC4H702 163° 0. Valerianic, or Amyl, or Pentyl Alcohol, CsHjj-O-H 137 ° C. Pentylic Acid, HC5H902 185° 0. Caproic, or Hexyl Alcohol, C6H13-0-H 157 0 C. Hexylic Acid, HC.jlIjjOj 205° 0. Heptyl “ C7H16-0-H 176 ° C. (Enanthic, or lleptylic Acid, HC7H1302 224° C. Cap rylie, or Octyl “ C8H17-0-H 195 ° C. Octylic Acid, HC8H1502 233 ° 0. Melting Melting Point. Point. Cetyl Alcohol, C16H33-0-H 50° C. Palmytic Acid, HCl6H3102 62° C. Stearic Acid, 1IC18H3502 69.2°C. Ceryl “ C27H65-0-H 79° C. Cerotic Acid, HC27H5302 78° C. Melissyl “ C30H61-0-H 85° C. Melyssic Acid, HC39H5902 88° C. ALCOHOLS. Formula. Boiling Point. FATTY ACIDS. Formula. + Boiling Point. METHYL ALCOHOL (Wood Spirit). CH3-0-H. Boils at 66° C. (150.8° F.) 547. Methyl Alcohol occurs among the products of the destructive distillation of wood, forming about one per cent, of the distillate. The alcohol is separated from the other products by careful fractional distillation. It is then redistilled after adding lime. This is then treated with dry calcium chloride, with which the alcohol combines to form a solid, crystalline body, from w’hich other impurities may easily be separated; the alcohol is recovered from this solid by distilling with water. The water is finally removed by treating with quicklime, and distilling at 260 ORGANIC CHEMISTRY. a low temperature. Oil of wintergreen consists chiefly of methyl ether of salicylic acid. On distilling this oil with potassium hydrate, pure methyl alcohol is obtained. Methyl alcohol is a transparent, colorless, mobile liquid, having a spirituous odor and a sp. gr. of 0.8142. It burns with a bluish flame. It is miscible with water in all propor- tions. By oxidation, it yields formic acid. ch3oh + o2 = cho2h + h2o. With acids, it produces ethers. With acetic acid, it gives methyl acetic ether, or methyl acetate, CH:i—0—C2H30. With hydrochloric acid, it gives methyl chloride, CH;,C1. Many other ethers and substitution products are known. The physiological action of methyl alcohol is similar to that of common ethyl alcohol, but more transient. Methylated spirit is a mixture of 90 parts of common alcohol and 10 parts of methyl alcohol. 548. Chloroform, CHC13.—Methyl chloride is acted upon by chlorine to produce a series of successive substitution pro- ducts, one of which, trichlor methane, is known under the name of chloroform. It was discovered in 1831 by Sou- beiran and Liebig. On a manufacturing scale, it is usually pre- pared from common alcohol, as follows: In 24 parts of water, dissolve 6 parts of chloride of lime, strain into a retort, heat to 40° C. (104° F.), and add one part of strong alcohol. A reac- tion soon sets in, developing sufficient heat to distill over the chloroform. This distillate forms commercial chloroform. Chloroform is a colorless, mobile liquid, possessing a peculiar, sweetish, ethereal odor and taste. It boils at 61° C. (142° F.) and has a sp. gr. of 1.525 at 0° C. (-f-32°F.). It is not miscible with water, is uninflammable in air, and dissolves fats, resins, caout- chouc, sulphur, phosphorus and iodine,—the last with a violet colored solution. Commercial chloroform is apt to be contaminated with alcohol, aldehyde and lower substitution products, and thus readily becomes useless on keeping. Purified chloroform, U. S. P., is prepared from the above by mixing it with sulphuric acid, agitating, drawing off the chloroform, neutralizing with a solution of sodium carbonate, again drawing off, adding lime and alcohol, and finally distilling the chloroform in a water bath. Pure chloroform must not affect litmus, must not color a mixture of H2S04 and chromic acids green, must not turn brown with H2S04, or KOH, and must not suddenly evolve inflammable gases when heated with alcoholic solution of potassium hydrate. It should not give a precipitate with silver nitrate, nor a yellow ALCOHOLS. 261 color with solution of potassium iodide. No foreign odor should be observed on allowing a few drops to evaporate on the hand. Chloroform prevents putrefactive decomposition and fermentation. Physiological Action.—When applied to the skin, chloro- form acts as an irritant, and, if evaporation be retarded, as a vesicant. The vapor, when inhaled, produces anaesthesia. When used for this purpose, it should be quite pure, and some air should be admitted with the vapor when adminis- tered. The fatal accidents that have occurred in its use as an anaesthetic, are due to a paralysis of the heart, and, in some cases, at least, may be attributed to the exclusion of air from the lungs. It is safer with children, and with women in parturition, than with ordinary adults. It is eliminated slowly, and when injected hypodermically, the effect is slow in making its appear- ance and lasts for several hours. It should not be administered to persons who are subjects of organic heart or renal disease. 549. Iodoform, CHI3.—This compound is prepared by acting upon common alcohol, aldehyde and many other com- pounds with iodine, and potassium hydrate or carbonate. It crystallizes in yellow scales which, under the microscope, resemble the beautiful forms of snow-flakes. It has a penetrating, saffron-like odor, melts at 120° C. (248° F.), and volatilizes slowly at ordinary temperatures. It is insoluble in water but soluble in alcohol, ether, chloroform, bisulphide of carbon and fixed and volatile oils. It is neutral in reaction and volatilizes completely on strongly heating. Physiological Effects.—Iodoform is a stimulant and an- esthetic when applied to wounds, and is much prized by many surgeons as an antiseptic dressing for wounds after operation. It prevents putrefactive decompositions and acts as a deodorizer, but its own odor is disagreeable to many persons. Bromoform, CHBr;i, nitroform, CH(N02)3, and a number of similar compounds are also known, but are not used in medi- cine. 550. Ethyl Alcohol, Common Alcohol, C2H5OH.—It is prepared from saccharine liquids by the growth of a micro- scopic plant called yeast, or ferment. The process is called fer- mentation. Cane sugar, starch and cellulose can be fermented only after conversion into glucose or levulose, which can be ac- complished slowly by the yeast itself. H H20 — C6H1206 + C6H1206. Glucose. Levulose. C6H1206 = 2C2H60 + 2C02. 262 ORGANIC CHEMISTRY. This reaction accounts for only 94 to 96 per cent, of the sugar employed, the remaining part being transformed into other pro- ducts, such as succinic acid, glycerine, “ fusel oil,” etc. The yeast plant, under whose influence this change takes place, is known as Torula, or Micoderma cerevisise. The sugar to be fermented may be from the juices of fruit or sugar-cane, or it may be previously prepared from starch of the cereals by the aid of malt or sulphuric acid. The secondary, or side products in the fermentation vary somewhat with sugar from these various sources, and thus give rise to the different flavors of the fermented liquors. The alcohol may be separated from the water and other products after the fermentation by careful frac- tional distillation. If it be desired to prepare an alcohol con- taining more than 90 per cent., some substance must be added which will combine with and hold back the water, as quicklime, anhydrous copper sulphate, potassium carbonate, or barium hydrate, after which it is again distilled. Absolute alcohol is a colorless, limpid liquid, of an agreeable odor and burning taste. It attracts water and mixes slowly with this liquid in all proportions, with the production of heat and contraction in volume. It boils at 78.4° C. (173° F.) and has never been solidified. It is neutral to test paper and burns readily with a non-luminous flame. It dissolves resins, essential oils, alkaline hydrates, calcium chloride and a large number of organic bodies. Oxidizing agents convert it into aldehyde and, finally, into acetic acid. Nitric acid (fuming) decomposes it very rapidly, giving a number of acids and ethers. If 90 per cent, alcohol is added to a solution of mercury or silver in nitric acid, a rapid ebullition takes place, with a crystalline deposit of ful- minate of silver or mercury, which explodes by percussion, and is used in filling percussion caps. The formula are CN.C(NH2) Ag2 and CN.C(NH2)Hg. The alkaline metals attack alcohol and give ethylates of the metals. 2C2H5OH -f K2 = 2C2H5OK + Ha. Acids form with it compound ethers. Physiological Action.—Alcohol is, when concentrated, a poison. Even when taken in large doses well diluted, it has frequently caused death, probably by paralysis of the muscles of respiration or of the heart. In full doses, it causes a feeling of warmth in the stomach, followed by congestion of this organ. After absorption, there is at first a feeling of exhilaration with ex- alted animal functions, quickened pulse and increased circulation, ALCOHOLS. 263 with dilatation of superficial blood vessels. This is often accom- panied and always followed by incoherence of ideas and muscu- lar actions, and finally, a general weakness of all the voluntary actions. The temperature is lowered, both in health and in most diseased conditions. The prolonged use of alcoholic beverages is characterized by general degenerative changes, either fatty or fibroid. There are no conclusive arguments to prove the bene- fit to be derived from the use of alcohol in health, but in certain diseased conditions it is of undoubted value. Commercial Forms.—Commercial alcohol varies in strength from 85 to 95 per cent. The U. S. P. strength is 91 per cent, by weight, and 94 per cent, by volume. Alcohol Dilutum contains 45.5 per cent, by weight, or 53 per cent, by volume. Tinctures are solutions of medicinal substances in alcohol. 551. Alcoholic Beverages are usually of three classes; viz., distilled, fermented and malt liquors. To the first class belong spirits, distilled from fermented liquors ; brandy, from wine; whisky, from a mash of corn or rye; rum, from mo- lasses; gin, from corn spirit flavored with juniper berries. To the second class belong the various wines. To the third class belongs beer, prepared from malted barley and hops.* Ale, porter and stout differ from beer only in the selection and pro- portion of the malt, hops and flavoring materials. We introduce here some results of the analyses of various dis- tilled liquors, as found in the American market, for the purpose of comparison as to the ordinary strength of alcohol (N. Y. State Board of Health Report, 1882). Brandy. Whiskey. Bum. Specific Gravity, 0.9297 to 0.9615 0.9018 to 0.9646 0.9126 to 0.9684 Per cent. Per cent. Per cent. Alcohol ' By Volume, 30.80 to 50.40 28.90 to 60.30 26.40 to 50.30 . By Weight, 25.39 to 42.96 23.75 to 52.58 21.66 to 42.87 It seems, therefore, that there is a great variation in the strength of these liquors as ordinarily sold ; and while they are supposed to contain from 40 to 50 per cent, of alcohol by volume, in reality, they usually contain from 35 to 45 per cent. It is, therefore, a very uncertain way of prescribing alcohol, to pre- scribe any one of these beverages. A much more certain method * Glucose is now very generally used to take the place of part of the malt. 264 ORGANIC CHEMISTRY. is to prescribe alcohol of known strength, flavored with ethereal essences, and softened with glycerine or syrup. Wines contain from 6 to 25 per cent, of alcohol. Port Wine 16.62 to 23.2 per cent. Sherry “ 16.00 to 25.0 “ Bordeaux, Red 6.85 to 13.0 “ “ White 11.00 to 18.0 “ Champagne 6.80 to 13.0 “ Beers and porters contain from 1 to 10 per cent., average about 4 to 5 per cent, by volume. The average of extractive matters (dextrin, cellulose, sugar, lupulin and hop resin) is 4 to 15 in ale, 4 to 9 in porter, and about 5 per cent, in beer. All alcoholic beverages are subject to gross adulterations. Artificial beverages are frequently sold in all markets. 552. Amyl Alcohol—Fusel Oil,* Potato Spirit, C5HuOH. This alcohol is formed in small quantities at the same time with ethyl alcohol, during the fermentation of barley, corn, and especially potato mash. It is prepared from the residue left in the still, after the common alcohol is distilled off, by fractional distillation. The product coming over at 132° C. (269° F.) is that collected. It is a colorless, oily liquid, possessing a peculiar, irritating odor which excites coughing, and a burning taste. It is not miscible with water, but mixes in all proportions with alcohol and ether. It is a good solvent of certain alkaloids. Taken internally it acts as a poison, both in the form of vapor and when taken by the stomach, producing dizziness, headache and intoxication. Much of the unwholesomeness of imperfectly rectified spirituous liquors arises from their contamination with fusel oil. The principal use of fusel oil is as a source of amyl ethers, which are used extensively to prepare artificial flavoring extracts. Thus, the acetate has the odor of pears, and is used by confectioners under the name of “ pear oil,” while the vale- rianate is used to give the flavor of apples, and called “ apple oil.” The special description of the remainder of the mon- atomic and the diatomic alcohols, or glycols, will be omitted, as they are comparatively unimportant. * Fusel oil, properly speaking, is a mixture of several alcohols of which amyl alcohol is one- TRIATOMIC ALCOHOLS. 265 TRIATOMIC ALCOHOLS, OR GLYCERINES. 553. Ordinary Glycerine, C3H5(OH)3, was discovered by Scheele in 1779, and was called by him the sweet principle of oils. It is prepared on a large scale from the neutral fats, as a side product in the manufacture of soap and candles. These fatty bodies are composed of fatty acids in combination with glyceryl, the radical of glycerine; i.e., they are compound ethers of the fatty acids and glyceryl. On treating these ethers with alkalies a salt of the alkali and acid is formed, termed a soap; the glycerine is set free by the reaction and remains dis- solved in the water present. This process of decomposing a compound ether into an alcohol and acid or salt of the acid is called saponification. Neutral fats can also be saponified by treating them with superheated steam, which is the process now usually employed, in candle factories, at least. The glycerine is freed from the water by evaporation, and finally, by distillation with the aid of superheated steam. Glycerine is also formed during alcoholic fermentation, and is found in wines, etc. It is a colorless, syrupy liquid, possessing a sweetish taste and no odor ; density 1.28 at 15.5° C. (60° F.). The officinal glycerinum has a density of 1.25. It is soluble in all proportions in water and alcohol, but not in ether. It absorbs water readily (hygroscopic) until it has absorbed twice its own volume. Its range of solu- bility is large, as will be seen by the table in the appendix. When heated in air, it boils at 290° C. (554° F.), and distills with partial decomposition. At low temperatures, it forms, under certain circumstances, a crystalline mass. When heated in the air to a high temperature, it takes fire and burns, leaving no residue. Boracic acid imparts a green color to its flame, or to a flame directed upon a platinum wire moistened with it. (This is one of the most convenient tests for boracic acid.) Chemically, glycerine is, as above stated, a triatomic alcohol; i. e., it contains three hydroxyl groups. When oxidized, it yields glyceric acid. It is capable of undergoing some kinds of fermentation, as butyric fermentation. It unites with the alkalies and alkaline earths soluble in water, and thus prevents the precipitation of some of the metals by reagents which ordinarily precipitate them. It. prevents the precipitation of copper hydrate by sodium or potassium hydrate, and has been recommended for this purpose in the preparation of Fehling’s test solution for glucose. Glycerine is sometimes adulterated with glucose, cane sugar syrup and water. The first and second of these will usually be easily detected by adding a solution of sodium hydrate (caustic 266 ORGANIC CHEMISTRY, soda) and enough copper sulphate to impart a blue color, and boiling for a few minutes, when the red cuprous oxide will be pre- cipitated if these be present. The presence of water may be detected by taking the specific gravity, which should not be below 1.25. Glycerine is the basis of the manufacture of nitro-glycerine used in various forms of blasting agents, such as “ dualine,” “ dyna- mite,” “ giant powder,” “ rend rock,” etc., which are usually com- posed of nitro-glycerine and some porous substance in powder form. Sulphuric acid combines with glycerine to form glycero- sulphuric acid. Glacial, or metaphosphoric acid forms glycero-phosphoric acid. C3H5(0H)2-P02=0=H2. This acid is one of the decomposition products of lecithin and protagon, two complex bodies found in nerve substance, especially of the brain. The acid itself has been found in the brain, nerves, muscles, yolk of egg, bile and pus. The phosphorus present in nerve matters probably exists in the form of either lecithin or protagon, both of which contain glycero-phosphoric acid. The salts of glycerine and organic acids will be referred to later. (See Neutral Fats.) (N03 554. Nitro-glycerine, or Glyceryl Trinitrate, C3H5 -j N03. (NO, —When glycerine is allowed to flow in a slow stream into a mixture of strong nitric and sulphuric acids kept cold by a freezing mixture, and the mixture afterward thrown into a large quantity of cold water, there separates out a heavy, colorless, poisonous oil—nitro-glycerine. It crystallizes at —20° C. (4° F.); sp. gr. 1.6. When inflamed in air, it burns quietly and rapidly; but when ignited by percussion or quick heating, especially in a confined space, it explodes with terrific violence, and hence is much used in blasting. 555. Tetratomic Alcohols.—None of this class of alcohols are of sufficient importance to be discussed here. HEXATOMIC ALCOHOLS. Formula, CnH2n—4(OH)6. 556. In the hexatomic alcohols the six hydroxyl radicals are united to six different carbon atoms, so that there must be six carbon atoms in the nucleus. This class of alcohols include— Mannite, C6Hg(OH)6. Dulcite, C6H8(OH)6. CARBOHYDRATES. 267 557. Mannite.—This is the sweet principle of manna, and is found widely distributed in the vegetable kingdom. It occurs in celery, fungi and sea weeds, in the sap of the larch, the exuded sap of the apple, cherry, lime, etc., and the exuded sap of Fraxinus Ornus, which in the dry state forms commercial manna. It may be prepared artificially by acting upon grape sugar with sodium amalgam (nascent hydrogen), or by the so- called mucous and butyric fermentations of sugar. To obtain it from manna, dissolve in half its weight of boiling water, add some albumen, to clarify, and filter through cloth. On cooling, the manna separates out. It may also be obtained pure by extracting manna with hot alcohol, and crystallizing. It forms fine, silky needles when crystallized from alcohol, but large, transparent, rhombic prisms from the aqueous solution. Mannite is intensely sweet, sparingly soluble in cold, readily soluble in hot water and alcohol, and insoluble in ether. It can readily undergo lactic and butyric fermentations, but not alcoholic. It unites with many metallic oxides, and also forms a large num- ber of compound ethers. Mild oxidation produces mannitose, CsH70(0H)5. By further oxidation, it forms mannitic acid, C5H6(OH)5CO.OH, and saccharic acid, C4H4(OH)4 j qq OH- 558. Dulcite. This isomeride of mannite is found in dul- cose, or dulcite manna, a crystalline substance from Madagas- car, and in several plants. It has been prepared from milk sugar by treatment with sodium amalgam. The properties of dulcite resemble those of mannite. Sorbite is a third isomeride of manna, found in the mountain ash. 559. Closely allied to the alcohols, and by some classed as alcohols, is the class of bodies known as carbohydrates. They contain six, or a multiple of six carbon atoms, and twice as many atoms of hydrogen as oxygen. They may be divided into three groups:— CARBOHYDRATES. (1) SACCHAROSES. (2) GLUCOSES. (3) AMYLOSES. C12 (C6Hlo06)n. +Caue Sugar. -|-Dextrose, -|-Starch. +Milk Sugar. (Grape Sugar). -{-Glycogen. + Melitose. —Levulose. -{-Dextrin. -{-Melizitose. -1-Galactose. —Inulin. -fMycose. —Sorbin. Gums. Synanthrose. Eucalin. Cellulose. Inosite. Tunicin. 268 ORGANIC CHEMISTRY. All these compounds occur ready formed, either in plant or animal organisms. The three groups are connected by a close relationship; indeed, those of 1 and 3 are easily converted into the glucoses by ferments or by boiling with dilute acids, by which water is added to them. The saccharoses and amyloses may be regarded as anhydrides of the glucoses. The chemical constitution of only a few of these bodies is known, and the molecular weight, with certainty, of none. They all have the properties of polyatomic alcohols, and a few behave also like the aldehydes. The members of groups 1 and 2 dissolve in water, have a sweet taste and are called sugars. Most of them are optically active, or possess the power of rotating the plane of polarized light to the right (dextrogyrate) or to the left hand (lievogyrate). The right-handed substances are marked and the left-handed —. (1) SACCHAROSES 560. Cane Sugar.—Cane sugar occurs in the juices of many plants, in most sweet fruits, in the nectar of flowers and in honey. It is found in large quantity in the juice of the sugar cane (Sac- charum Officinarum), in sorghum (Sorgho Saccharatum), in beet-root, sugar-maple and in several species of palm. Sugar is obtained principally from sugar cane, beet-root, sor- ghum and the maple, while some attempts have been made to obtain it from the common maize. The juice of the sugar cane is expressed by passing the stalks between steel rollers; this is then mixed with milk of lime and heated to boiling to precipitate the coagulable materials, phos- phates, etc.; these are removed, and the clear liquid evaporated, either in open pans or in vacuum pans under a reduced pressure, to a thick syrup, and then left to crystallize. The “raw sugar ” is drained from the “mother-liquor,” which is further evaporated and again left to crystallize. There is finally left a thick, brown liquid, called molasses, or treacle, containing uncrystallizable sugar. The raw sugar is refined by dissolving in water, adding lime, and filtering through thick layers of bone charcoal to remove the color. It is then evaporated in vacuum pans and allowed to crystallize. Pure cane sugar crystallizes in large, transparent, monoclinic prisms, such as are seen in rock candy. It is soluble in one-third Ci2H220ii. MILK SUGAR. 269 its weight of cold, and in all proportions in hot water. It is slightly soluble in weak, but almost insoluble in absolute alco- hol. It melts at 160° C. (820° F.), and solidifies, on cooling, to an amorphous mass, called “ barley sugar.” The rotary power of sugar, in solution, is taken advantage of for its quantitative determination. The saccharometer is the instrument in common use for this purpose; its use depends upon the principle, that, in a solution of definite thickness, the rotary power of the solution is dependent upon the per cent, of sugar present, and by measuring the amount of rotation of the light, the amount of sugar in the solution can easily be determined. When cane sugar is boiled with dilute sulphuric acid, it takes up water and is converted into a mixture of dextrose and levu- lose, called inverted sugar. H + H20 — CH1206 + C6H1206. The same change takes place under the influence of yeast, probably from some soluble ferment contained in it. When heated above its melting point, it gives off water, turns dark, and forms a bitter, brown, amorphous substance, called caramel. At a higher temperature it continues to lose water, decomposes, and gives off inflammable gases, consisting of marsh gas, and carbon monoxide and dioxide; at a higher temperature a distillate is obtained containing aldehyde, acetic acid, acetone, etc. Strong sulphuric acid chars sugar, leaving a black, voluminous mass. Dilute nitric acid oxidizes cane sugar to saccharic acid, then into tartaric, and, finally, oxalic acid. Concentrated nitric and sul- phuric acids form with sugar a nitrate, C12H1807(N03)4, which is amorphous and very explosive. On heating with sulphuric acid and manganic oxide, a large quantity of formic acid is formed. Cane sugar forms a series of metallic compounds called sucrates, or saccharates. An aqueous solution of sugar will dissolve calcium, barium, magnesium and lead oxides, and, with an alkali, copper and ferric oxides also. The barium salt crystallizes well. MILK SUGAR. 561. This is an important ingredient of the milk of mammals, and is prepared principally from cows’ milk by evaporating the whey after removing the cheese. Cows’ milk contains from 4 to 5 per cent, of sugar, while woman’s milk contains from 6 to 7 per cent. It crystallizes in large, hard prisms, has a feebly sweet taste, and is soluble in 6 parts of cold water. Yeast ferments Ci2H22 On 4" H20. 270 ORGANIC CHEMTSTRY. it with difficulty. Lactic and butyric fermentations take place readily. Oxidizing agents yield mucic and saccharic acids. It forms compounds, like cane sugar, with metallic oxides, and re- duces alkaline copper solutions. The remaining members of this group are unimportant. (2) GLUCOSES. 562. Dextrose, or Grape Sugar.—This sugar is widely- diffused through the vegetable kingdom, occurring in grapes, honey, in most sweet fruits, sprouting grains (Malt) etc., usually mixed with an equal weight of levulose. It occurs in small quan- tities in the blood, yolk of eggs, and urine, and in larger quantity, in diabetic urine. It is manufactured on a large scale from corn starch by boiling with dilute sulphuric acid, neutralizing with lime, drawing off the clear syrup after settling, and evaporating it down to a thick syrup and allowing it to crystallize. Dextrose is less sweet than cane sugar, 2k parts of the former giving the sweetening power of 1 part of the latter. It is frequently used to adulterate the light-brown varieties of cane sugar. When present in considerable quantities (5 per cent.) it may often be detected by its property of mashing between the teeth instead of crush- ing like cane sugar. Dextrose crystallizes with some difficulty, and, as usually met with in the market, it does not present to the naked eye a distinct crystalline appearance. It easily under- goes oxidation, especially in alkaline solutions, and thus acts as a reducing agent. It readily reduces silver, copper, bismuth and mercury salts in alkaline solutions. Silver, if ammonia be pres- ent, is reduced to the metallic state and deposits as a brilliant mirror on the surface of the vessel in which it is heated. The ordinary methods of detection and estimation of dextrose depend upon its reducing power. Fehling’s solution, which is in common use as both a qualitative and quantitative test for dex- trose, is a solution of 34.64 grins, of pure crystallized copper sul- phate, 173 grms. of Rochelle salt, and 80 grins, of sodium hydrate in a litre of distilled water. 1 c.c. of this solution is exactly re- duced and decolorized by 5 milligrams of dextrose. For quali- tative detection, alkaline solutions of copper, bismuth, indigo- carmine, picric acid or silver may be used. Dextrose undergoes alcoholic fermentation with great ease and is used in large quantities in making beer. 563. Levulose.—This sugar occurs mixed with dextrose in the natural sources of that sugar, mentioned above. It is obtained AMYLOSES. 271 with dextrose in inverted sugar, prepared by heating cane sugar with dilute mineral acids. It differs from dextrose in its rotary power, which is left-handed instead of right-handed ; the other differences are of minor importance, except sweetening power, which is greater in this sugar than in grape sugar. 564. Galactose is obtained from milk sugar by inverting it with dilute sulphuric or hydrochloric acid. It is very ferment- able, and reduces alkaline copper solutions. Sorbin occurs in the berries of the mountain ash, and is not fermentable. Inosite has been found in the muscular substance of the heart, in the lungs, liver, kidneys, etc., and in some plants. It is very sweet, and crystallizes in large, rhombic prisms, soluble in water. It does not ferment with yeast, reduce the alkaline copper solutions, or invert with acids or alkalies; it is optically inactive. (3) AMYLOSES. 565. Starch, or Amylum.—This body is found in nearly all plants. It is most abundant in the cereals, rice, potatoes and the seeds of plants. Starch occurs in the form of microscopical granules inclosed in the cells of the plant where they occur, very much as fat occurs in adipose tissue. The granules, examined under the microscope, are seen to be possessed of a distinct organized structure, which is different in each different kind of starch. They show, under the microscope, several concentric markings, arranged around a nucleus, or hilum, which is situated nearer one edge. The sizes and markings of the starches from the various sources vary sufficiently to admit of identification, an important fact in the detection of adulterations in foods. Starch is prepared by grinding the grain or vegetable, and then suspending it in water, or spreading it on a sieve and running water upon it. By this means the starch granules are washed out of the cells and remain suspended in the water. This milky- looking liquid is allowed to settle, when the starch falls to the bottom; this sediment is taken out, dried, and sent into the market. Wheat starch is often prepared by suspending the flour in water and allowing it to stand until the gluten is dissolved by putrefactive fermentation, when the starch may be washed and dried. Starch is insoluble in cold water, alcohol and ether. Heated with water to a little above 60° C. (140° F.), the contents of the (C12H20Oxo)n. 272 ORGANIC CHEMISTRY. granules swell up, burst the envelopes and escape into the water. It appears at first as a very fine powder, but afterward disappears and forms an apparent solution, which, if concentrated, forms, on cooling, a jelly-like mass, called starch paste. On long boiling, starch enters into, a soluble form. The same change is produced by a dry heat of 100° C. (212° F.), by diastase, or dilute sul- phuric acid. With diastase it soon passes into the form of maltose and dextrin, and finally into dextrose. It forms me- tallic compounds with lead, lime and barium oxides. Soluble starch is precipitated by alcohol and solutions of subacetate of lead. Starch dissolves in cold concentrated nitric acid; on the addi- tion of water, xyloidin, a white powder, separates. The most characteristic reaction of starch is the dark blue color it forms with free iodine. This blue iodide of starch is easily decomposed, and disassociates when the solution is heated, but re-forms on cooling. 566. Dextrin, or British Gum, is an amorphous, yellow- ish-white, gum-like body, readily soluble in water. It is formed by heating starch above 150° C. (3023 F.), or by the first action of malt diastase, or hot dilute sulphuric acid upon starch. This change is a progressive one. When diastase or pancreatic fer- ment is added to gelatinous starch (starch paste), it is liquefied in a few moments and becomes soluble starch, which is represented by the formula, 10(C12H2o010). This is gradually hydrated under the action of the ferment, giving rise to eight different steps in the process, and eight different dextrins:— Soluble Starch, 10(C12H2OOlo) + H20 = 9(Cl2H20O + C12H22011 Maltose, Erythro-dextrin, A, 9(C12H20Oj0) + H20 = 8(Ct2H20Olo) + CI2H„0u “ Erythro-dextrin, B, 8(C12H20O10) + H20 = 7(C12H20Oio) + C12H22011 “ Acroo-dextrin, C, 7(C12H20010) + H20 = 6(C12H20010) + C12H220n “ and so on until the final result obtained is— Acroo-dextrin, F, 2(C12H20Oio) + H20 = 2(C12H20010) + no Maltose; that is, the final result always leaves a portion of dextrin un- changed into maltose. The final result is about 20 per cent, of acroo-dextrin to 80 per cent, of maltose. Pancreatic diastase, however, has the power of slowly changing maltose to dextrose, and the lowest acroo-dextrin to maltose. Iodine gives a reddish color with dextrin. 567. Glycogen.—This substance resembles starch, and occurs in the liver of man and several animals, in the embryo, yolk of egg and some mollusks. It dissolves in cold water to an opales- cent solution, but is insoluble in alcohol and ether. In mauy of AMYLOSES. 273 its properties it resembles dextrin. Its solutions are dextro- gyrate. A diet of starches, sugars, inulin, glycerin, albumin of egg, fibrin and casein causes an increase of glycogen in the liver; while inosite, quercite, mannite, gums and fats fail to do so. Violent exercise, prolonged starvation, or fevers, exhaust the liver of sugar. Glycogen of the liver is readily changed to acroo- dextrin, maltose and dextrose by a peculiar diastatic ferment found in the liver itself. Iodine gives a reddish-brown color with both dextrins and glycogen ; but the color returns with the latter after discharging it with heat. 568. Cellulose, or Lignin.—This forms the principal part of the solid framework of plants. The pure substance may be prepared by treating raw cotton or linen fibre with potassium hydrate, acids, and ether, to remove foreign matters. It is a white solid, exhibiting the structure of the fibre from which it is ob- tained. It is soluble in a solution of cupric hydrate in ammo- nium hydrate. On the addition of an acid to this solution, it is precipitated as a white, amorphous mass, which, mixed with cam- phor and compressed into various articles, is sold under the name of celluloid. Cellulose is insoluble in water, alcohol, ether and all ordinary solvents. Strong sulphuric acid dissolves it, and on diluting with water, white flakes separate. When boiled with dilute sulphuric acid, it is converted into dextrine and dextrose. When cotton-wool is steeped in a cold mixture of 1 part of strong nitric and 3 parts sulphuric acid for a few minutes, squeezed as dry as possible, placed in fresh acid for 48 hours, then pressed dry, and finally washed thoroughly in water, then in a weak solution of sodium carbonate, it possesses, when dry, great explosive properties, and is called gun cotton.' The appearance and physical properties of the cotton remain un- changed, but it becomes a nitro-cellulose, the composition varying with the mode of preparation. Pyroxylin is used as a source of collodion; it is a nitro- cellulose, containing less N03 groups than gun cotton. It is pre- pared by dipping cotton into a mixture of 10 parts HNO:, and 12 parts of H2S04, allowing it to steep for 10 hours or until it is soluble in a mixture of alcohol and ether (1 to 3), then remov- ing and washing it in cold water. Collodion is prepared by dissolving 4 parts of pyroxylin in a mixture of 70 parts ether and 26 parts alcohol. Flexible collodion is a mixture of 92 parts of the above, 5 parts tur- pentine, and 3 of castor oil. Styptic collodion owes this property to 20 per cent, of tannic acid. 274 ORGANIC CHEMISTRY. If dry unsized paper be dipped into a cold mixture of 2 parts of sulphuric acid and 1 of water for a few seconds, and then washed quickly in cold water containing a little ammonia, it is rendered very tough and strong, and is called parchment paper. GUMS. 569. Although these bodies cannot be regarded as belonging to the polyatomic alcohols, they seem to be closely associated with them. The gums are amorphous bodies, more or less soluble in water, but insoluble in alcohol, and are converted into one of the glucoses by dilute sulphuric acid. 570. Gum Arabic and gum-senegal are derived from dif- ferent kinds of acacia. They occur in rounded, irregular masses, which dissolve in water to form a thick, viscid solution. These gums are composed of the compounds of potassium and calcium with arabin. Arabin treated with dilute H2S04 yields arabinose, C6H1206, a non-fermentable glucose. Cerasin is the insoluble part of the plum and cherry tree gums, which also contain arabin. Gum-tragacanth is the hardened juice of some kinds of astragalus. Gum bassorin is obtained from a species of cactus; it is insoluble in water, but swells up therein to a jelly-like mass. Many other plants furnish mucilages or gum-like bodies. 571. Ethers are of three kinds; simple, mixed and com- pound,- which have already been defined. (See Art. 541.) The simple ethers are usually prepared by the action of acids upon the corresponding alcohols. They bear the same relation to alcohols that oxides of the metals do to their hydrates. Potassium hydrate, KOH. Potassium oxide, K20. Ethyl alcohol, C2H5OH. Ethyl ether (C2H5)20. The simple ethers are mostly liquids, slightly soluble in water, soluble in alcohol, possess a peculiar odor, and when acted upon by alkalies, regenerate the alcohols. ETHERS. ETHYL ETHER. 275 ETHYL ETHER or ETHYL OXIDE. Synonyms: Yinic ether, sulphuric ether, common ether. 8:5: \o 572. Common Ether is prepared by heating a mixture of ethyl alcohol and sulphuric acid, and distilling over the result- ing ether. About 6 or 7 parts of commercial alcohol and 1 part of strong sulphuric acid are introduced into the retort, which is provided with two openings. Into one of these a thermome- ter is placed, while into the other is inserted a funnel tube. The retort is heated until the thermometer marks 130°C. (266°F.). Alcohol is now allowed to run in slowly through the funnel tube, while the temperature is kept between 130° and 140°C. (266° to 284°F.). The ether distils off with the water produced, and a small quantity of alcohol and sulphurous oxide. The crude ether floats upon the water as a distinct layer. To obtain it in a pure state, it is washed with dilute soda solution, dried over quicklime and calcium chloride, and redistilled by the heat of a water bath. By the above process, a small quan- tity of sulphuric acid may be made to etherize a very large quantity of alcohol. The action takes place in two stages, as follows: Sp. gr. 0.736. Boils at 35.5°C. (96°F.) C2H5OH + H2S04 = (C2H5)HS04 + h2o, Alcohol. Ethylsulphuric acid. C2H5HS04 + C2H5OH = C2H5-0-C2H5 + H2S04. Ether. Properties.—Pure ether is a very volatile, mobile liquid, possessing a characteristic odor and burning taste. It is soluble in ten volumes of water and in all proportions in alcohol. It is highly inflammable, burning with a luminous flame; in hand- ling it, therefore, care should be taken not to come near a flame. It dissolves resins, oils and many other organic bodies. It dis- solves iodine, bromine, corrosive sublimate, sulphur and phos- phorus. For anaesthetic purposes, it should not affect blue litmus; it should leave no residue when a quantity is evaporated on a watch glass, nor should it leave a foreign odor; it should boil in a test tube when the latter is held in the hand, and it should not impart a blue color to ignited copper sulphate (absence of water). A small quantity of alcohol, less than 6 per cent., is not a serious objection. 276 ORGANIC CHEMISTRY. COMPOUND ETHERS. 573. There are a large number of these compounds known, but a few only are met with in medicine. Acetic Ether (C2H5—O—C2H30) is prepared by distilling a mixture of strong sulphuric acid, alcohol and sodium acetate. The distillate is washed with a solution of calcium chloride and milk of lime, decanted, dried over calcium chloride, and finally redistilled. Acetic ether is a colorless, limpid liquid, boiling at 74°C. (165°F.) and possessing a pleasant, fruity odor. It dis- solves in about 10 parts of water, the water becoming acid from decomposition of the ether into acetic acid and alcohol. The refreshing smell of hock-vinegar and some old wines, is due to the presence of acetic ether. The ether is inflammable, burning with a bluish-yellow flame and acetous odor. 574. Amyl Acetate (C5HU—O—C2H30) is prepared by distilling a mixture of amyl alcohol, sulphuric acid and sodium acetate. It has a pleasant, ethereal odor. Ethyl benzoate, valerianate, butyrate, nitrite, nitrate, etc., are prepared very much in the same way as the above, substituting the salts of the acids here indicated for the sodium acetate. 575. Ethyl Nitrite, or Nitrous Ether (C2H5—O—NO) is a mobile liquid, boiling at 16.5°C. (61°F.), It has a sp. gr. of 0.947, and is insoluble in water, but freely soluble in alcohol. It is prepared by distilling a mixture of alcohol, potassium nitrite and sulphuric acid, or by gradually heating a mixture of equal parts of alcohol and strong nitric acid until it begins to boil; then remove the heat and allow it to distill slowly. It is purified as described above for the other ethers. Sweet Spirit of Nitre is a mixture of ethyl nitrite, ethyl alcohol, aldehyde and acetic ether. It is prepared by adding together sulphuric acid, alcohol and nitric acid, and heating gradually to 80°C. (176°F.), when it is kept near this tempera- ture while the ether distills over. This ether is now added to 19 times its weight of alcohol. 576. Amyl Nitrite (C5H„—O—NO) is prepared by passing nitrogen trioxide, N203, into amyl alcohol. It is a colorless or slightly yellow liquid, boiling at 99°C. (210.2°F.), and possesses the choking smell of amyl compounds generally. It boils at 96° G. (205° F.), specific gravity .872 to .874. Its vapor when in- haled, produces at first a sense of fullness and dizziness in the head; then flushing of the face, increased heart action, and lowering of the blood pressure and temperature. It may con- 277 tain, as impurities, nitric acid, amyl nitrate, amyl valerate, and hydrocyanic acid. 577. Artificial Fruit Flavors.—These flavoring extracts have come into use extensively in recent years, and are manu- factured largely from various mixtures of compound ethers, organic acids and glycerin. The following formulae will give some idea of the character of these mixtures: Pine Apple consists of chloroform, one part; aldehyde, one part; ethyl butyrate, five parts; amyl butyrate, ten parts, and glycerin, three parts. Strawberry, of ethyl nitrate, one part; ethyl acetate, five parts; ethyl formate, one part; ethyl butyrate, five parts; methyl salicylate, one part; amyl acetate, three parts ; amyl butyrate, two .parts; glycerin, two parts. Pear, of ethyl acetate, five parts; amyl acetate, ten parts; benzoic acid, one part, and glycerin, ten parts. The ethers are to be dissolved in pure alcohol (specific gravity .83), and the numbers given indicate the quantity to be added to 100 parts of alcohol by measure. These mixtures, when taken in large quantities, produce deleterious effects ; but, as the quantities actually used are very small, they probably have no such action. Besides the above mentioned and many other “ fruit essences,” these ethers are also extensively employed to improve the flavor of poor wines, and to fraudulently imitate wines, brandy, rum, whiskey, etc. ORGANIC ACIDS. 578. An organic acid is built upon the water-type, and may be regarded as one or more molecules of water in which one-half the hydrogen is replaced by a compound organic radical containing oxygen; asH—O—H,H—O—C2HsO, q j C4H404 (com- pare Art. 545). The number of organic acids known is very large; only a few of the most prominent ones can, therefore, be mentioned here. Of the many series of acids, the most numerous and important are those of the acetic or fatty acid series, corresponding to the marsh gas series of hydrocarbons. The acids of this series are obtained by the oxidation of the corresponding alcohols or aldehydes. ORGANIC ACIDS. C2H5—0—H + 02 = C2H30—0—H + H20. Alcohol. Acetic Acid. 2C2H3—0—H + 02 = 2C2H30—0—H. Aldehyde. Acetic Acid. 278 ORGANIC CHEMISTRY. They may also be obtained by the action of the alkaline hydrates upon the cyanides of the radical of the next lower alcohol. A few have been obtained by synthesis from carbon monoxide. CH3Cy + KOH + H20 = NH3 + KC2H302. CO + KOH = CHO—0—K. Formic Acid. THE FATTY ACID SERIES. MONATOMIC ACIDS. CnH-2a02 = Cu H2q -iO—0—H. Of the large number of acids in this group, we shall notice formic, acetic, butyric, valeric, palmitic, margaric and stearic. FORMIC ACID 579. Formic Acid is a colorless liquid, of a very acid reac- tion and sharp, pungent odor. It boils at about 100° C. (212° F.) and solidifies at about 0° C. (32° F.). It exists ready formed in the red ant, stinging nettle and pine needles. It acts as a reduc- ing agent, reducing silver and mercury salts and depositing the metals. It is used in silvering glass to reduce the silver, which deposits upon the walls of the containing vessel.' The best method of obtaining it is by heating to about 100° to 110° C. (212° to 230° F.) pure anhydrous glycerin and dry oxalic acid, adding more oxalic acid from time to time, and continuing the distilla- tion. Carbon monoxide dissolved in potassium hydrate, yields some potassium formate. cho—o—H. ACETIC ACID C2H30—0—H. 580. Acetic Acid occurs frequently in the form of acetates in some vegetable and animal fluids. It is usually obtained by the fermentation of saccharine fluids after they have undergone the alcoholic fermentation, or by the dry distillation of wood, starch, etc. In distilling wood, gases, methyl alcohol (wood spirit), acetic acid, water, creasote and tar are obtained. The liquid portion is distilled at a gentle heat, when the alcohol is separated. The remaining liquid, containing the acetic acid, is saturated with sodium carbonate, evaporated to dryness, and heated to 250° or ACETIC ACID. 279 350° C. (482° to 662° F.) to char the tarry matters. The residue containing sodium acetate is dissolved in water, filtered, and allowed to crystallize out. If the free acid is desired, the residue, after carbonizing, is distilled with a slight excess of sulphuric acid. This gives a colorless, strongly acid, sour- smelling liquid, which crystallizes at about 17° C. (63° F.) and is known as glacial acetic acid. Acetic acid applied to the skin blisters, and causes considerable pain. It acts as a styptic when not too strong. It is soluble in water, alcohol and ether in all proportions. It dissolves resins, camphor, fibrin and coagulated albumin. It precipitates mucin, and is used to separate this body from its solutions. It is also used, with the aid of heat, as a test for albumin ; but care is taken not to add too much, as it dissolves the albumin. Under the action of chlorine, acetic acid furnishes a series of chlorine substitution compounds, in which the chlorine is substituted for the hydrogen of the radical; thus, we have monochlor, dichlor and trichlor-acetic acids. and C2CI3O2H. The last of these is mentioned elsewhere as a test for albumin in urine. 581. Vinegar.—This name is given to the mixture obtained by the fermentation of wine, cider, whiskey, molasses, infusion of malt, etc., under the influence of the growth of mycoderma aceti, and should contain at least four per cent, of acetic acid. Alcoholic fermentation always precedes the acetous. As vinegar always contains more or less of this ferment, called mother of vinegar, it is customary to add some of this fluid to start the process. The fermentation takes place slowly, in vats or casks, because of the small amount of surface presented to the air. The process is rendered very much more rapid' by allowing the fluid to trickle over beech-wood shavings or chips placed upon trays or in perforated barrels, so as to expose a large surface to the air. After having passed over the shavings four times, it will be found to be pretty thoroughly acetified. The temperature should be kept at about 25° C. (77° F.). The vinegar of the market is frequently adulterated with 1, water; 2, mineral acids, especially sulphuric; 3, metallic impurities, as arsenic, lead, zinc, copper and tin ; 4, wood vine- gar ; 5, organic substances, such as coloring matters, capsicum, etc. The addition of water can only be detected by the estima- tion of the per cent, of acetic acid. 280 ORGANIC CHEMISTRY. The most objectionable adulterant is sulphuric acid. The simplest method of detecting free mineral acids is to evaporate a portion of the vinegar to dryness ; then heat the residue to dull redness for some time, to convert the acetates of the alkaline metals into carbonates, which can easily be detected by their effervescence with hydrochloric acid. If any free mineral acid existed in the vinegar, it would expel the acetic acid from the alkalies and convert them into sulphates, which remain un- changed on ignition. Another test for mineral acids is methyl violet. Two or three drops of a solution of this compound (0.1 to 100) added to 25 c. c. of vinegar, remains unchanged if pure. If .2 per cent, of any mineral acid be present, the color is blue ; if .5 per cent., blue-green ; if 1 per cent., green. A simple test for sulphuric acid is to evaporate a portion to dryness in a white porcelain dish, with a little cane sugar. At the end of the process, the residue becomes black by the charring of the sugar by the acid. A small quantity of sulphuric acid is sometimes added to make the vinegar keep. The poisonous metals likely to be found are mercury (corrosive sublimate), copper, arsenic and lead. These metals may be detected by saturating the vinegar with hydric sulphide, or by separate tests for each. Burnt sugar, capsicum, etc., may be detected by taste or odor in the residue left on evaporation. The acetates are eliminated from the body as carbonates. BUTYRIC ACID. 582. This acid is found with other fatty acids in butter, human perspiration, faeces, in flesh juice, and in some beetles. It exists in butter as a glyceride or glyceric ether. Pathologically, it appears in a free state in urine, blood, and ovarian cysts, and in the sputa of gangrene of the lung and bronchiectasis. It also appears in the intestinal contents as the result of secondary fermentation of saccharine articles of food. It is best prepared by maintaining at a temperature of 35 to 40°C (95° to 104°F.) a solution of sugar containing lime or chalk, and sour milk or rotten cheese. A mixture of 10 parts of sugar, 1 part of cheese, and 10 parts of chalk answers very well. Lactate of calcium is first produced, which afterward changes, under the influence of the ferment of cheese, into butyrate of calcium. The solution should remain alkaline or neutral. Carbon dioxide and hydrogen are set free. When the fermentation is finished, C4II70.0—H. VALERIC. 281 30 or 40 parts of crystallized sodium carbonate is added, and the mixture is warmed and filtered. The filtrate is evaporated nearly to dryness, and hydrochloric or sulphuric acid added, which sets free the butyric acid as an oily layer, which may be purified by distillation. It boils at 162°C. (323°F.). It is a colorless liquid with the characteristic penetrating odor of rancid butter. It is soluble in pure water, but separates if soluble salts are added to the solution. It is soluble in alcohol, oils and ether. The buty- rates are all soluble in water. Isobutyric acid, an isomer of the foregoing, is obtained by oxidation of secondary or isobutylic alcohol. The following graphic formulae show the constitution of these bodies:— H H H H H H H I I I I I I I _0 H-C-C—C—C—0—H H—C-C—C—C“X TT llll III H H H H H H H Butylic Alcohol. Butyric Acid. H H H H H H III III H—C—C—C—H H—C—C—C—H III III H H H | H H —C ® n=0 11 0—H — 0—H Isobutyl Alcohol. Isobutyric Acid. VALERIC, or VALERIANIC ACID. 583. Occurs in valerian root, and is obtained by distilling tlie powdered root with water. It is best prepared by the oxida- tion of amylic alcohol. A mixture of one part of amyl alcohol and four parts of concentrated sulphuric acid is run slowly into a retort containing four parts of water and five of potassium dichromate. The first product is valeraldehyde, which distills over. By ele- vating the beak of the retort so as to run the aldehyde back into the oxidizing mixture, it is changed into valerianic acid. The mixture is finally distilled, the distillate neutralized with sodium carbonate, evaporated and decomposed with sulphuric acid. Valerianic acid is a thin, oily liquid, boiling at 175°C. (347°F.), and possessing a sour, old cheese odor. The most of the valeri- anates are soluble in water, and, when moist,‘smell like the acid. Valerianates of ammonium, bismuth, caffeine, quinine, iron and zinc are used in medicine. cbh9o.oh. 282 ORGANIC CHEMISTRY. OLEIC (C18H3402), PALMITIC (CI8H3fi02), AND STEARIC (C16H3202) ACIDS. 584. These three acids exist as glycerides in most fats and oils. Palmitic acid melts at 62°C. (143.6°F.), stearic at 69°C. (156°F.), and oleic is liquid at temperatures above 4°C. (39°F.). When once solidified, this last acid melts at 14°C. (57°F.). Neither of these acids distills without decomposition. The acids are separated from the glycerin by saponifica- tion ; i. e., by treatment with caustic alkalies, or, still better, by superheated steam (see Glycerin). Stearin candles are com- posed of a mixture of stearic and palmitic acids. The salts of these three acids with metals, are called soaps. The only solu- ble soaps are those containing potassium (soft soap) or sodium (hard soap). On adding a solution of one of these soaps to a solution containing one of the heavy metals, an insoluble soap is precipitated. All are familiar with the calcium and magnesium soaps, which form as a curdy precipitate on adding ordinary soap to hard water. Lead Plaster (diachylon plaster) is a lead soap, prepared by saponifying olive oil with litharge, PbO. 585. Monobasic Acids containing Alcoholic Hydroxyl. —But two acids of this group are worthy of special mention ; viz., glycollic and lactic acids. CH —O—H Glycollic Acid, I is found in unripe grapes, and CO—0—H in the green leaves of Virginia creeper. When pure, it forms large, regular crystals, which deliquesce in moist air, and melt at 79° C. (174° F.). ch3 . . I . Lactic Acid, CH.—0—H = C3H(i03 is the acid of sour I CO.O—H milk and sour cabbage, and is produced by a special ferment, called lactic ferment. It is found in small quantity in the gastric juice, urine and intestinal juices. It is produced on a large scale by lactic fermentation of cane sugar and glucose. Flour is first treated with dilute sulphuric acid, to convert the starch into glucose ; the free acid is then neutralized with milk of lime. To this is then added sour milk, and it is allowed to ferment; care being taken to stop the process DIBASIC ACIDS. 283 before butyric acid fermentation sets in, by heating the mixture to boiling. The hot solution of calcium lactate is separated by filtration, evaporated down, and allowed to crystallize. From this salt, the acid may be obtained by saturation with sulphuric acid. A solution containing 75 per cent, of the acid is officinal in the U. S. P. It is a colorless, syrupy, odorless, very acid liquid, freely miscible with water, alcohol and ether. It is used in the preparation of syrup of the lactophosphates, U. S. P. Ferrous Lactate is used in medicine. It occurs in pale, greenish-white, odorless, crystalline crusts or grains, permanent in air, and soluble in water. DIBASIC ACIDS. OXALIC ACID CO.O—H I = HaCaO* CO.O—H 586. This important acid exists in many plants (Oxalis,. Rumex, Rhei) as calcium or potassium oxalates. Calcium oxalate is also found in the urine. Oxalic acid is easily obtained by acting upon many organic substances with oxidizing agents. Glycol, glycollic or acetic acids may be made to yield it. It is best prepared from the carbo-hydrates (sugar, starch, etc.) by treating them with strong nitric acid or by fusing with caustic potash. Commercial oxalic acid is prepared by fusing sawdust with a mixture of caustic soda and potash. The acid crystallizes in colorless prisms with two molecules of water, which they lose at 100° C. (212° F.). It is soluble in eight parts of cold water, and in alcohol. It is very sour and poisonous. Antidotes are chalk, lime, or magnesia. On heating the acid it is resolved into carbon monoxide, dioxide, water and formic acid. Strong oxidizing agents convert it into carbon dioxide and water. It is a strong dibasic acid, and forms both acid and neutral salts with most of the metals. 587. Succinic Acid—Acidum Succinicum. COOH I ch2 I = C4H804. ch2 (loon This acid is found ready formed in amber and some other resins, in several plants, and in the animal organism. It is one of the products of alcoholic fermentation of sugar, and may be 284 ORGANIC CHEMISTRY. prepared by the action of reducing agents on malic and tartaric acids. It may be obtained in quantity by the dry distillation of amber ; the aqueous portion of the distillate is heated to boiling, and filtered; on cooling, crude succinic acid crystallizes out. Succinic acid crystallizes in monoclinic prisms, melting at 180° C. (356° F.), and decomposing into water and succinic anhy- dride at 235° C. (455° F.) It is soluble in 23 parts of cold water, and very freely soluble in hot water. By adding neutral solution of ferric chloride to a soluble succinate, a brown, gelatinous, ferric succinate is produced ; this is a reaction used as a qualitative test for the acid. The succinates of the alkaline metals are soluble ; those of the other metals are either slightly soluble or insoluble. DIBASIC ACIDS CONTAINING ALCOHOLIC HYDROXYL. MALIC ACID. CO.O—II I ch2 I = c4h606. CH.O—H I CO.O—H 588. Malic Acid occurs in many acid fruits, as cherries, apples, raspberries, gooseberries, rhubarb (stalks and leaves), unripe mountain ash berries, unripe grapes and quinces. It is best prepared by nearly saturating the boiled and filtered juice of the berries of the mountain ash with milk of lime. On con- tinued boiling, calcium malate, CaC4H3(H0)04.H20, separates as a crystalline powder, from which the acid may be obtained by treatment with dilute nitric acid. Malic acid crystallizes in groups of small, colorless, deliquescent crystals. It melts at 100° C. (212° F.),and decomposes at 150° C. (802° F.). Putrefactive ferments convert malic into acetic, succinic, butyric and carbonic acids. There are three isomeric malic acids possible, of which two are known. The alkaline malates are soluble ; other malates are slightly soluble or insoluble; all are crystalline. TARTARIC ACID. 285 TARTARIC ACID. CO.O—H I CH.OH I = c4h606. CH.OH I CO.O—H 589. Tartaric Acid is a dibasic, tetratomic acid. (Compare the formulae of succinic, malic, and tartaric acids.) Four isomeric, tartaric acids are known ; two of which—dextro and laevo-tartaric acids—are optically active, and two—racemic and mesotartaric acids—are optically inactive.* Ordinary, or dextro-tartaric acid is found in man'y fruits, particularly in ripe grapes, as acid potassic tartrate (cream of tartar), which, during the fermentation of the must, is deposited, mixed with yeast, coloring matter, calcium tartrate, etc., as a brown crust, or deposit, known as crude argol. Tartaric acid is prepared from argol by first treating with hot water, filtering, decolorizing with animal charcoal, converting the acid potassium tartrate into calcium tartrate by the addition of milk of lime, then decomposing this with sulphuric acid. Tar- taric acid is thus obtained in solution, and may easily be separated by crystallization. Tartaric acid is usually made in the same factories where cream of tartar is prepared in large quantities. It usually occurs in beautiful, oblique prisms, permanent in the air, soluble in one-half their weight of water, or in 2.5 parts of alcohol, and insoluble in ether. When heated, it melts at 180° C. (356° F.), and forms metatartaric and pyrotar- taric acids, and tartaric anhydride (C4H405). At higher tem- peratures it decomposes with a burnt-sugar odor. Tartaric acid has a strong, acid taste. It precipitates calcium in neutral or alkaline solution, but not in strong acid solutions. Ammonium salts prevent this precipitation. Heated with hydriodic acid and phosphorus, tartaric is first changed into malic, and then succinic acids. The principal tartrates are the neutral and acid potassium tar- trates, sodio-potassium tartrate (Rochelle Salt) and tartar emetic, or antimonyl potassium tartrate, all of which are men- tioned in another place. Ferro-potassium tartrate and ferro- ammonium tartrate are also used in medicine. They both belong to the class of substances known as scale compounds; i. e., compounds which do not crystallize readily and are prepared by spreading the material, evaporated to a syrup, upon plates of glass to dry, and then scraping off the thin scales. The above 286 ORGANIC CHEMISTRY. mentioned compounds occur in the form of garnet-red scales, slightly deliquescent, very soluble in water, but insoluble in alcohol. Tartaric acid is used in making effervescing drinks, in calico printing, and by confectioners, to prevent the crystallization of the sugar. When taken in too large quantities, it acts as an irritant poison. One ounce has caused death. TRIBASIC ACIDS. CITRIC ACID. CHj.CO.OH CH.CO.OH = C6H604(0H)3. I * CH.(OH)CO.OH 590. This acid occurs in the juice of lemons, currants, goose- berries, beet roots and other plants. It is manufactured on a large scale from lemon juice, which is clarified by boiling it with albumin, and then saturated, while hot, with powdered chalk or milk of lime. The precipitated calcium citrate is decom- posed by an equivalent quantity of sulphuric acid, and filtered from the resulting gypsum. On evaporating the filtrate, the acid crystallizes out in large, transparent, rhombic prisms, having an agreeable, sour taste, and containing one molecule of water of crystallization. The acid melts at 100° C. (212° F.), and is readily soluble in water and alcohol. At 175° C. (347° F.), the acid loses water, and is converted into aconitic acid, C6H303 (OH)3. Solutions of citric acid soon develop mould, and are thereby decomposed. Citric acid forms three, classes of well defined salts with the metals; citrates of the alkaline metals are soluble in water. The citrates are decomposed into carbonates in the body, and, in the case of the citrates of the alkalies, are eliminated by the kidneys as carbonates ; hence, these citrates are frequently prescribed in acid conditions of the urine. Citric acid is not known to exert any injurious action upon the economy, even in considerable quantities. Citrates of bismuth, iron, iron and ammonium, iron and quinine, iron and strychnine, lithium, potassium, bismuth and ammonium, and syrup of citric acid are officinal in the U. S. P. When boiled with excess of lime water, citric acid precipitates basic calcium citrate. This distinguishes it from oxalic and tartaric acids. ACIDS OF THE BENZOL SERIES. 287 ACIDS OF THE BENZOL SERIES. CH 591. Phenic, or Carbolic Acid, HCX C—Q—H XHC=CH/ = C6H5OH, which is, in reality, phenyl alcohol, also called phenol, is met with in the products of the destructive distillation of coal and wood, and is found in small quantities in human urine, and in castoreum. In the arts, it is prepared from that portion of the coal tar oil, distilling between 150° C. (302° F.) and 190° C. (374° F.). This is agitated with a concentrated solution of caustic soda, when a crystalline carbolate of sodium is formed, while the neutral oils are left unacted upon. After the latter have been separated, the carbolate is decomposed by hydrochloric acid, and the impure carbolic acid thus obtained again treated with sodium hydrate. On exposing this solution to the air, the greater portion of the impurities become oxidized, and separate as a tarry mass. The clear solution of sodium phenate (or carbolate) is again decomposed by hydrochloric acid, and the resulting carbolic acid separated and submitted to distil- lation. From the portion passing over below 190° C. (374° F.) phenol separates out as colorless needles on cooling, which melt at 42° C. (108°F.) and boil at 184° C. (364° F.). Pure phenol is a crystalline solid, having a characteristic odor and pungent, caustic taste, producing a white eschar with animal tissues. The crystals are liquefied by the addition of about 5 per cent, of water. This liquid is made turbid by the addition of more water, until 2000 parts are added, when the acid dissolves to a clear solution. It is soluble in twenty parts of water at the ordinary temperature. The addition of glycerin increases its solubility. It is readily soluble in alcohol, ether, benzol, carbon disulphide, glycerin, and fixed and volatile oils. Carbolic acid coagulates albumin, and its aqueous solution gives a permanent violet-blue color with ferric chloride, while that produced by creasote changes to green and then brown. It forms a white precipitate with bromine water. When quite pure, car- bolic acid is permanent in the air ; but the commercial acid frequently changes to a pink or red color. Ammonia and chlo- rinated soda solution produce a blue color with carbolic acid. Carbolic acid is very much used as an antiseptic in medicine and in the arts. Some of the carbolates have also been used for the same purpose. Carbolic acid is very poisonous when taken into the body, and cases of fatal poisoning by it are not uncommon. 288 ORGANIC CHEMISTRY. Dangerous symptoms have been produced by six or seven drops, and fatal poisoning has occurred from its use as a dressing of wounds. The urine in such cases is dark-colored and smoky, and its appearance should be watched while using the acid, either internally or locally. 592. Sulpho-carbolates.—If one part of crystallized car- bolic acid is mixed with one part, by weight, of strong sulphuric acid, phenyl-sulphuric or sulpho-carbolic acid is formed. If this solution is diluted with water and barium carbonate added in excess, a solution of barium sulphocarbolate is pro- duced. From this, other sulphocarbolates are obtained by double decomposition. The sulphocarbolates are all soluble in water, glycerin, and alcohol. The following salts have been used in medicine:—Potassium Sulpho-carbolate, KCsH5S04.H20, crystallizing in shining needles; Calcium Sulpho-carbolate, Ca(C(iH5SO,02-6H.2O, which forms scaly crystals; Magnesium Sulpho-carbolate and Zinc Sulpho- carbolate, crystallizing in rhombic prisms. These salts may be taken internally in doses of 10 to 30 grains. They prevent fer- mentation in organic solutions. PICRIC, OR CARBAZOTIC ACID. 593. When phenol and a number of other bodies containing the benzol nucleus, such as salicin, indigo, balsam of Peru, silk, wool, etc., are treated with strong nitric acid, a yellow, very bitter, crystalline, trinitro-phenol is obtained, which is known as picric acid. It is used as a yellow dye for silk and wool, and as a test for albumen in urine. When quickly heated, it deton- ates. It is soluble in alcohol, and slightly so in water. ( OTT 594. Dihydro-phenol, or Hydroquinone, CeH4 j is of little importance to the physician. Resorcin, C6H4 j Qjq, has come into prominence recently in the treatment of certain maladies. It forms colorless crystals, melting at 99°C. (210°F.), and boiling at 271°C. (519°F.). It is very soluble in water, and possesses a sweetish, harsh taste. It is prepared by fusing certain gum resins (galbanum), extract- of sapin-wood, or Brazil-wood, with caustic potash. It is a strong anti-fermentative. C6H3(N03)3—0—H. BENZOIC ACID. 289 PYROGALLIC ACID. I 0—H C6H3$0-H. (0—H 595. This acid is a triphenol, and is prepared by heating gallic acid, CGH2(0H)3C02H, to 300°C. (572°F.). It crystallizes in white, shining needles, and gives a dark-blue color with ferrous, and red with ferric salts. An alkaline solution, when exposed to the air, rapidly absorbs oxygen and assumes a dark color. Silver and gold salts are reduced, in the light, to the metallic state by it; hence it is used as a developer in photography. BENZOIC ACID. H TT C — CH \j—CO—O—H=C7H602H \ / Hc = c 11 H 596. This acid occurs in gum Benzoin and in the leaves of the aspen ; also found in the urine of herbivorous animals. Benzoic acid is prepared from gum benzoin by sublimation. The powdered resin is gently heated in an iron pan covered with a perforated paper cover ; over this is placed a paper or felt cone ; the benzoic acid is sublimed and collects on the inner surface of the cone. It is also prepared by boiling the resin with milk of lime, filtering, concentrating the filtrate by evapora- tion, and precipitating the acid with hydrochloric acid. It is also prepared from naphthalene, Ci0H8, occurring in coal tar, and from hippuric acid found in the urine of cows. Properties.—Benzoic acid occurs in large, thin, brilliant plates, or needles ; it melts at 120°C. (248°F.) and boils at 250°C. (482°F.), but sublimes at a lower temperature. It is soluble in hot water and alcohol, but sparingly soluble in cold water. It has a peculiar, aromatic, irritating odor. The benzoates are generally soluble in water. The benzoates of ammonium, lithium and sodium are officinal. The one most used is ammonium benzoate. This salt occurs in colorless, transparent, prismatic crystals, or in white and granular crystals, becoming yellow on long exposure to the air. It has a slight odor of the acid, a saline, afterward bitter taste; soluble in 5 parts of water. The sodium salt is soluble in 1.8 parts of water, has a sweetly astringent taste, is free from bitterness, and has a neutral reaction. 290 The acid and its salts have an antifermentative and antiseptic action. Solutions of benzoates give a flesh-colored or reddish precipi- tate with ferric chloride. ORGANIC CHEMISTRY. SALICYLIC, OR OXYBENZOIC ACID. HC = C-°-H / \ HC C—CO—0—H = C6II4(0H)C02H = C7Ha03. \ S C —0 H H 597. This acid occurs in the flowers of several species of C QJJ spircea, and its methyl ether, C6H4 j (j()OCH orms a arSe part of oil of wintergreen, from which it was formerly prepared. It is now prepared on a large scale by passing C02 into a heated retort containing sodium carbolate. C6H5O.Na + C02 = C6H4(0H)C0.0Na, When pure, salicylic acid occurs as fine, white, prismatic, needle- shaped crystals, permanent in air, having a sweetish, slightly acrid taste and acid reaction; soluble in 450 parts of cold water, and in 2.5 parts of alcohol. Its solutions give an in- tense violet color with ferric salts. This is used as a test. The salicylates of lithium, sodium and some of the alkaloids are used in medicine. The salicylic ethers are very numerous. 598. Closely related to salicylic acid is a glucoside of oxyben- zoic alcohol, called salicin. p rr f OH L6ilHCH2OH. Oxybenzoic Alcohol. p rr / OH °«±1nCH20(C6H1105). Salicin. Salicin is found in the bark of different kinds of willow and poplar, and in castoreum. It is prepared by boiling the bark with water and lead oxide, filtering, precipitating the lead with hydric sulphide, and evaporating down. The salicin separates from the solution in fine, colorless, needle-like prisms, having a very bitter taste and neutral reaction; soluble in 28 parts of water, and in 30 parts of alcohol; insoluble in ether or chloroform; very soluble in hot water. It is used in medicine. ORGANIC BODIES CONTAINING NITROGEN. 291 HIPPURIC ACID. 599. This acid is found in the urine of herbivorous animals, and in small quantity in human urine. When benzoic acid or oil of bitter almonds is taken internally, hippuric acid appears in the urine. It is generally prepared by evaporating the urine of the cow or horse to one-tenth its volume, and precipitating with hydrochloric acid. It forms large, rhombic prisms, soluble in hot but sparingly in cold water. cbh9no3. URIC ACID. 600. Uric acid is found in the urine of all animals, and in the excrement of birds, as ammonium urate. Human urine in the healthy state contains but a small quantity of the acid, but it is increased in most febrile disorders, in acid dyspepsia, and in diseases of the lungs. As uric acid is very sparingly soluble in water, it often crys- tallizes out as a sediment, and in some gouty subjects, the acid sodium salt crystallizes out in certain regions in the vicinity of the joints. Uric acid is a white, crystalline powder, without odor or taste. It is very sparingly soluble in cold and hot water. It is a dibasic acid. The urates of the alkaline metals are more soluble than the acid. Lithium urate is more soluble than the potas- sium salt, and potassium more soluble than the sodium salt. The acid salts are less soluble than the normal, and the acid sodium salt frequently separates from the urine on cooling, or during acid fermentation, as a reddish-colored deposit—“brick- dust” or “ lateritious ” deposit. Uric acid may be detected by evaporating the solution nearly to dryness, with nitric acid, when, on the addition of ammonia to the yellow residue, a deep reddish-violet color is produced (murexid). Under the microscope, uric acid from urine appears as yellow crystals, and is notable for the variety of forms it assumes. c5h4n4o3 ORGANIC BODIES CONTAINING NITROGEN. AMINES, AMIDES, IMIDES, NITRILES. 601. Thus far we have said nothing of the ammonia type CH of compounds. Ammonia, N \ H, is a type of a large number of (H compounds, most of which belong to organic chemistry. 292 ORGANIC CHEMISTRY. An amine may be regarded as formed by replacing one or more atoms, in ammonia molecules, by positive or hydrocarbon radicals. When formed from one molecule of NH3, they are monamines; when from two or three, they are called diamines or triamines. Primary, secondary and tertiary.amines are formed by replacing one, two, and three atoms of hydrogen respectively. We may represent these different classes of amines as follows :— Primary. (C2h5 Ns H . (H Ethylamine. MONAMINES. Secondary. (CH8 N -I CH3. (h Dimethylamine. Tertiary. fCH3 n] c6h5. ( C6H5 Methyl-diplienyl-amine, fH N S H. (H Ammonia. f H2 nJh2. (h2 Condensed Ammonia. f C2H4 n2 -< h2. 1h2 Ethylene-damine. DIAMINES. f C6H4 n2 c6h4. (h2 Diphenylene-diamine. f c2h4 nJ c2h4. ( ( C 2 H 5 ) 2 Diethylene-dietliyl- diamine. Amines all have basic properties and combine directly with acids, like NH3, to form salts. 602. Amides.—These compounds may be regarded as formed by replacing the hydrogen atoms in ammonia with negative or acid radicals, as:— HI H IN. c2h3oj Acetamide. These bodies are classified and named like the amines. Second- ary and tertiary amides, with very few exceptions, are unknown. They differ from the corresponding acids in containing amidogen, NH2, in place of hydroxyl, OH. Thus :— hoc2h,o. Acetic Acid. H2N-C2H30. Acetamide. h2o2co. Carbonic Acid. (H2N)2CO. Carbamide (urea). Acid Amides are formed by replacing a part of the hydro- gen in a polybasic acid by amidogen, NH2, thus:— NH2.HO.CO. Carbamic Acid. nh2hoc2o2. Oxamic Acid. The hydrogen of the amidogen in these compounds may be further replaced by hydrocarbon radicals, thus :— w ji | JN2±l31 CfiH5. Phenyl Oxamid. nit I C2H20 0—H \ CvH50. Hippuric Acid. AMINES. 293 603. Imides.—An imide differs from an amide in containing the radical NH, where the latter has NH2, thus— nh2co.oh—h2o = nhco. Acid Carbamide Carbimide. The carbamides are converted by heat into isomeric bodies, which may be regarded as compounds of nitrogen with a triad radical, and known as nitriles, thus:— f (C H ) N2 j H, gives N { C,H6i H20 and CN.C2H5. (.CO L Diethyl Carbamide. Propionitrile. • Ethyl Cyanide. 604. Of the large number of possible compounds which belong to this class of bodies, we can only mention one or two in detail. As before mentioned, the amines are bases, or organic alkalies. They unite directly with acids to form salts, and, with platinic and auric chlorides, to form double salts similar to those of am- monia. When heated, amines expel ammonia from its salts. The lower members of the group are gases, while the higher members are liquid or solid. The natural alkaloids seem to belong in this group, and will be mentioned in this connection. As perhaps the most important artificial amine, we 'may c c6h5 mention aniline (phenyl amine), N -j H. 605. Aniline is obtained from benzol, by first converting this into nitrobenzol by the action of concentrated nitric acid.— AMINES. c6h6 + hno3 = c6h5no2 + h2o. Nitrobenzol is generally a brown or pale yellow, strongly re- fractive liquid, boiling at 220° C. (428° F.) ; has a burning, sweet taste; an odor resembling that of bitter almonds and cinnamon. It is used in perfumery under the name of essence of mir- bane. Taken internally, it is a violent poison. When treated with nascent hydrogen, generated by zinc and sulphuric or hydrochloric acid, aniline is produced.— C6H5N02 + 3H2 = C6H5NH2 + 2H20. Nitrobenzole Aniline. The aniline combines with the acid present, forming crystallizable 294 ORGANIC CHEMISTRY. salts. Like all the amines, it acts as a base, uniting directly with acids. Aniline is, when pure, a colorless, oily, refractive liquid, boiling at 182° C. (359° F.), and is insoluble in water. It is the basis of a large number of beautiful coloring matters very much employed in dyeing and calico printing. In 1858 Perkins obtained a purple dye by acting upon aniline oil with potassium dichromate and sulphuric acid. Other colors were soon obtained ; greens, yellows, reds, blues, violets and black have all been obtained from aniline. These dyes are soluble in alcohol and glycerine, and are used for a variety of purposes; they are not very permanent dyes. Aniline is easily detected by the addition of a solution of sodium hypochlorite (chlorinated soda), with which it gives a purple-colored solution. NATURAL ORGANIC BASES, OR ALKALOIDS. 606. Many plants, and especially those having medicinal and poisonous properties, contain basic principles, or compounds con- taining nitrogen, which are called alkaloids. Some are vola- tile, while others decompose when heated. Most of them re- semble the amines or compound ammonias in properties, while some correspond more nearly to the ammonium compounds. Most alkaloids are sparingly soluble in water, more freely in alcohol, the solutions having an alkaline reaction and bitter taste. They combine directly with acids, like NH3, forming crystalline salts, which are generally soluble in water. Their hydrochlorides form crystalline double salts with the chlorides of gold, platinum, mercury, etc. Most of them are precipitated by solutions of tannin, the double iodide of potassium and mercury, double iodide of cadmium and bismuth, by phosphomolybdic, phosphoan- timonic, phosphotungstic, and picric acids, and by a solution of iodine in potassium iodide, or in hydriodic acid. These reagents are, therefore, used to separate the alkaloids from other sub- stances found with them. By treating these precipitates with an alkaline hydrate, the bases are-separated. PROPERTIES OF NATURAL ALKALOIDS. 607. The following tables give the formulae and solubility in water, benzol, ether and chloroform ; also source, appearance and leading properties. The limits of this work will not allow us to go further into this subject. PROPERTIES OF NATURAL ALKALOIDS. 295 Name. Formula. Soluble in Water. Ammonia Water. Benzol. Ether. Chloro- form. Source. C17H23NO3 C21H18N065Aq c4h6n2o 2^ c20h24n2o c18h21no3 c17h19no5 c8h15n C2 4 H 3 8 NO 2 c17h21no4 c30h44N2o4 C22H23N06 c16h23no3 c17h19no3h2o C23h29no9 C22H23N07 csh7n c20h21no4 S. in 150 pts. S. in 60 pts. S. S. In 500 pts. boiling. In 90 pts. In 2500 pts. boiling. In 2000 pts. In 75 pts. Soluble. In 100 pts. Insol. S. in 704 pts. S. S. s. Insol. S. in hot. S. in 500 pts. boiling. S. in 200 pts. boiling. S. in 7000 boiling. S. Insol. S. S. s. s. s. s. s. Insol. In 75 pts. S. S. S. s. s. s.s. S. in hot. s. s. s. s. Insol. S. Insol. S. S. in 50 pts. S. in 60 pts. S. S. S. in 12 pts. S. S. s. s. s. s. Insol. S. S. S. in 25 pts. S. S. in 40 pts. S. in 2 pts. S. in 30 pts. Insol. Insol. S. in 500 pts. S. in 400 pts. S. in 150 pts. S. s. S. in 6 pts. S. s. Nearly insol. Insol. S. S. s. Insol. In sol, S. in 120 pts. S. s. s. S. in 234 pts. S. in 4 pts. S. S. S. in 4 pts. S. in 5 pts. S. in 60 pts. S. S. s. s. s. Insol. S. s. S. in 90 pts. S.S. S. in 3 pts. S. S. S. Aconitum Napellus. Atropa Belladonna, i Berberis Vulgaris. ( Calumba root. Nux Vomica. Coffee and Tea. Cinchona bark. Cinchona bark. Opium. Colchicum Autumnale. S Water Hemlock. \ Conium Maculatum. Delphinum Staphisagria. Erythroxylon Coca. Ipecacuanha. Ergot of Bye. Hydrastis Canadensis. Hyoscyamus Niger. Opium. Opium. Opium. Tobacco (Tabacum), Opium. NATURAL ALKALOIDS. 296 ORGANIC CHEMISTRY. Name. Formula. Soluble in Water. Ammonia Water Benzol. Ether. Chloro- form. Source. Physostigmine (Eserine). C15H21N3O2 S. S. S. S. S. S. s. Calabar bean. Pilocarpine (Hydrochlor- ide) C11HI6N202HC1 S. del. s. s. Insol. In sol. Jaborandi. Piperine Pseudomorphine 04 Nearly insol. Insol. Insol. S. S. in 90 pts. Insol. S. Insol. Cayenne pepper. Opium. Quinine S. in 1800 pts. S. s. S. S. in 50 pts. Cinchona bark. Quinidine c20ii24n2o2 S. in 750 pts. S. S. in 30 pts. S. Cinchona bark. Bhceadine 2lN06 Insol. Insol. S. S. S. in 1300 pts. S. S. Opium. Strychnine C22H24N 2O2 S. in 6500 pts. S. S. S. in 160 pts. Insol. S. in 7 pts. Nux vomica. Thebaine C19H21NO3 Insol. (cold). Insol. S. in 18 pts. S. S.S. Opium. Theobromine C7H8N402 S. in 750 pts. S. s. s. Nearly insol. s.s. Cocoa Nuts. Yeratrine S. in 1000 pts. hot. s. s. s. S. in 12 pts. S. in 2 pts. Yeratrum Alba. Urea CH4N20 S. s. S. S. Urine. Daphnin C3lH38019 s. s. s. Nearly insol. Several Bpecies of Daphne. Digitalin CioH1804 s. s. S. s. S. S. S. S. Foxglove. Digitalis. Picrotoxin c12h1405 S. in 50 pts. s. S. S. in 250 pts. S. Cocculus Indicus. Salicin 8^7 S. Nearly insol. Insol. Willow leaves. Solanin S. in 8000 hot. Insol. S. S. S. in 4000 pts. Insol. Bittersweet. Saponin 54018 S. S. Insol. Saponaria officinalis. * Largely from Prescott’s “Prox. Organic Anal.” Explanation—S., soluble; S. 8., slightly soluble. The numbers indicate the quantity of water required to dissolve one part of alkaloid. NATUKAL ALKALOIDS. GLUCOSIDE ALKALOIDS. PROPERTIES OF NATURAL ALKALOIDS. 297 608. Separation and Detection.—The alkaloids are sepa- rated from other substances and from each other by the use of various solvents, the principal ones being indicated in the pre- ceding table. As most of the alkaloids or their salts are soluble in alcohol, this reagent is generally employed to extract them from plants or from other solid matters. After acidifying with acetic acid, digesting and filtering, the alcohol may be evaporated off, and the residue exhausted with ether, benzol, naphtha, chloro- form, etc. Or, after acidifying, we may digest for some time with water, filter, and treat the filtrate with ammonium or sodium hydrate, or milk of lime. The alkaloids are thus precipitated, and may be separated by filtration, redissolved, converted into salts and purified by recrystallization. The limits of this work will not permit us to enter into this subject fully, and the student is referred to works on chemical analysis for further particulars. 609. Properties of Principal Alkaloids.—Aconitine.— Glacial mass, or white powder, crystallizes with difficulty, in rhombic plates. It possesses a sharp, pungent taste, and in general, the physiological properties of the plant. With phospho- molybdic acid, it gives a yellow precipitate. Aniline.—A colorless, oily liquid, turning dark on exposure; characteristic odor; boils at 1823 C. (359° F.); gives red or violet color with NaOCl solution. (See Art. 605.) Antipyrine, Dimethyl Oxichinine ? (Alkaloid).—The hydrochloride is the salt used. It is a grayish-white, crystalline powder, with a weak, tarry odor, and bitter, somewhat acrid taste. It is readily soluble in alcohol and lukewarm water, from which it does not readily separate on cooling. Alkalies precipi- tate it, ferric chloride colors it reddish-brown, and nitrous acid colors it green, even in very dilute solutions (1 to 10,000). It is used, in doses of 15 to 30 grains, as an antipyretic. Atropine.—Prisms ; stellated tufts, white and fusible; bitter taste ; dilates the pupil either when free or as salts. The alka- loid and its sulphate are officinal in the U. S. P. Brucine.—Crystallizes in plates or prisms; lievogyrate ; less poisonous than strychnine. With strong nitric acid gives a red, then yellow color ; SnCl2 gives deep violet. Caffeine.—White, silky needles; fuses and sublimes; has a faint, bitter taste; poisonous in large doses; 0.4 to 0.5 grains produce death in cats and rabbits. Cinchonine.—Four-sided needles, fusible. Its solutions are dextrogyrate; chlorine and ammonia give yellow precipitate; 298 ORGANIC CHEMISTRY. separated from quinine by insolubility in ether ; very bitter, and has less tonic properties than quinine. Sulphate officinal. Cinchonidine.—Hard, rhombic prisms, with striated faces ; differs from above in being lsevogyrate. The sulphate is offici- nal. Cocaine.—Monoclinic, glistening prisms, with bitter taste, leaving a benumbing effect on the tongue. Heated with strong HC1, it decomposes. The hydrochloride has powerful local antes- thetic properties. Coca leaves are used as a stimulant in Peru. Codeine.—Rectangular prisms, isomorphous with morphine. Forms soluble crystalline salts, from which caustic soda precipi- tates the alkaloid. Colchicine.—Yellow-white powder or colorless needles. Conine.-—Liquid ; boils at 168° C. (335° F.) ; highly poison- ous ; odor of hemlock, and sharp, nauseous taste ; decomposes on exposure to air. Hyoscyamine.—Silky needles in groups, or amorphous and pasty; when impure, has a nauseous smell; dilates the pupil like atropine. It has sedative properties. The sulphate is offi- cinal. Morphine.—Short, transparent, trimetric prisms. When heated, loses water and melts to a colorless liquid; salts soluble in water; bitter taste ; gives blue color with Fe2Cl6; decomposes iodic acid, giving free iodine. Noted for its anodyne properties ; less exciting, and gives less after effects than opium. Officinal salts, sulphate, hydrochloride and acetate. When heated with large excess of HCl,it gives apomorphine, which is precipitated as a white powder by sodium carbonate, and turns green on ex- posure. Speedy emetic; said to be formed spontaneously in old morphine solutions. OTHER -OPIUM ALKALOIDS. Oxymorphine (Pseudomorphine). Codeine. Thebaine. Codamine. Laudanine. Protopine. Papaverine. Meconidine. Laudanosine. Rheadine. Cryptopine. Narcotine. Lanthopine. Narceine. Physostigmine (Eserine). — Crystalline or amorphous brown-yellow powder; solutions red to blue, of strong alkaline reaction; violent poison; strongly contracts the pupil. The salicylate is officinal. OTHER OPIUM ALKALOIDS. 299 Picrotoxine.—Colorless tufts of needles; reduces alkaline copper solutions ; has an intensely bitter taste. Piperine.—Colorless, tasteless, inodorous prisms, melting at 100° C. (212° F.). Alcoholic solution has sharp, peppery taste and neutral reaction. Soluble in alcohol. Pilocarpine.—Uncrystallizable, but salts crystallize from alcohol. With H2S04, it forms a colorless solution. The nitrate and hydrochloride are much used in medicine. Given internally, they produce rapid and profuse diaphoresis and salivation, quick- ened pulse and lowered temperature. With large doses, the heart stops in diastole. The hydrochloride is officinal. Quinine.—Fine needles. Alkaloid seldom used. Sulphates, salicylate, tannate, hydrochloride and numerous salts in use. Forms basic, neutral and acid salts. Basic Quinine Sulphate, (C20H24N2O2)2H2SO4.8H2O, is manufactured on a large scale, and is found as long, brilliant needles, which effloresce and form white powder. This salt is not very soluble (1 in 780 parts water ; more readily in alcohol). All salts have an intensely bitter taste. Normal Quinine Sulphate, C20H24N2O2.(H2SO4)2.7H2O, forms transparent four-sided prisms. Made from the basic salt by adding H2S04. Soluble in eleven parts of cold water. Acid Quinine Sulphate (Bisulphate), C20H24N2O2(H2SO4)2. 7H20, forms soft, white prisms, freely soluble in water, exhibiting beautiful blue fluorescence. Solution of iodine precipitates from the acetic acid solution of basic sulphate, a tourmaline-like, crystalline body, of a green reflection. The solutions of quinine and its salts have a left-handed rotary power on light. When dissolved in chlorine water, ammonium hydrate produces a deep emerald-green solution. If K4FeCyG be first added, NH4OH gives a deep red color. Quinine and its salts have a tonic and antiperiodic action on the economy. The sulphate, bisulphate, hydrobromide, hydrochloride and valerian- ate are officinal. Quinidine.—Large prisms, soluble, with difficulty, in water, but soluble in alcohol. Gives quinine reaction with chlorine and ammonia; bitter taste and tonic effects, similar to quinine. Right-handed rotary power. Salts resemble those of quinine. The sulphate is officinal. Salicin.—Tabular or scaly crystals. A glucoside. (See Art. 598.) 300 ORGANIC CHEMISTRY. Strychnine.—Four-sided trimetric prisms, white and fusible. Bitter taste can be detected in a solution containing one part in one million parts of water. Forms soluble crystalline salts. Sulphate and phosphate are used largely in medicine. Violent poison, producing tetanic convulsions. The antidotes are mor- phine, atropine, and chloral hydrate. A delicate test is to dissolve in sulphuric acid and add a fragment of potassium dichromate, when a deep purple color is produced. The sulphate is officinal; but other salts are used in medicine. Theobromine.—Small, trimetric crystals, in club-shaped groups. It has a slightly bitter taste. Salts are unstable, and decompose in contact with water. Veratrine.—White prisms or powder, melting at 115° C. (239° F.) and solidifying, on cooling, to a resinous mass. Its dust causes violent sneezing; it is a violent poison. H2S04 con- centrated, forms a yellow solution, which gradually becomes red. It forms crystalline salts. The oleate is officinal. PTOMAINES. 610. Putrefactive, or Cadaveric Alkaloids.—These alka- loids are produced during the putrid decomposition of animal and vegetable matter, and probably in certain pathological con- ditions in the human body during life. A distinct alkaloid has been separated from pysemic fluid, and named septicine. Some of these bases are very poisonous, producing symptoms re- sembling those caused by strychnine, atropine, conine, etc. Selmi obtained poisonous bases containing arsenic, from the body of a subject who had died of arsenical poisoning, and was exhumed fourteen days after death. It is probable that some of the symp- toms of poisoning by preserved food, such as preserved fish, meat, etc., that are occasionally seen, are due to the presence of some one of these alkaloids. Tainted meat, fish, etc., should not be eaten. The author has known of a number of cases of poison- ing from this cause. Some of these alkaloids decompose with great ease, giving a cadaveric odor, while others remain permanent. Although they are most likely to be found in putrefying animal matters, they have been produced by the putrefaction of maize, leguminous substances, flour, etc. Many of the ptomaines are volatile and amorphous, but form crystalline salts with the acids. They answer to nearly all the ordinary reactions of the vegetable GLUCOSIDES. 301 alkaloids. They seem to possess less stability, and have a greater tendency to undergo oxidation than the vegetable bases, and hence frequently act as reducing agents. The number of the ptomaines seems to be large; and no one of them has been completely studied. The best test for the general detection of these bases, depends upon their power of reducing potassium ferricyanide to the ferrocyanide. The base is converted into the sulphate and brought into contact with a drop of potassium ferricyanide in a watch glass. A solution of ferric salt added to the watch glass will give a Prussian blue color if the ferricyanide has been reduced to the ferrocyanide, otherwise not. The reduction takes place rapidly. Unfortunately, a few of the vegetable alkaloids give this reaction as well as the ptomaines. No certain distinctive test has yet been devised. GLUCOSIDES. 611. The glucosides are a large class of compounds widely dis- tributed throughout the vegetable kingdom, which have the property of being resolved into a sugar and another compound, by acids, alkalies, or ferments. They are ethers of glucose. Some of them occur in the animal economy. We can mention here but a few of the more important of these bodies. Amygdalin, C20H27NOU, occurs in bitter almonds, in kernels of cherries, plums, apricots, and in leaves of laurel. Extracted from almonds by boiling alcohol, and precipitated by adding ether, it is obtained as pearly scales. Crystallizes in prisms. When emulsin (the ferment of bitter almonds) is added, it splits up into prussic acid, HCN, benzaldehyde, C6H5COH, and glucose. Arbutin, Ci;iHi607.—Extracted from leaves of Uva-Ursi. Soluble in water, has a bitter taste, and is crystalline. Emulsin and dilute acids yield glucose and hydroquinone. Antiarin.—The active principle of the arrow-poison of Java; crystalline, soluble in water and alcohol. Obtained from the milky juice of Antiaris toxicaria. Coniferin, C,6H2208, occurs in cambial layer of theconiferse, and crystallizes in stellate groups of prisms. Emulsin yields glucose and coniferyl alcohol. This latter, when treated with sulphuric acid and potassium dichromate, yields artificial vanil- lin, a body identical with that obtained from the vanilla bean. It is now manufactured on a considerable scale. Convolvulin, C31H50Oi6. Active principle of jalap; a resin- ous mass soluble in alcohol and alkalies. Jalapin exists with the above in jalap. 302 ORGANIC CHEMISTRY. Digitalin.—A poisonous substance existing in common fox- glove ; forms an amorphous powder having an intensely bitter taste. Composition not known. Esculin, C21H24013, and Esculetin, C9H604, occur in the bark of the horse chestnut tree ; sparingly soluble in cold, more freely in hot water, are crystalline and have a bitter taste. Fraxin, C32H3602, is found in the bark of the ash and horse chestnut tree, and forms colorless needle-like crystals, soluble in water, furnishing a bitter, fluorescent solution. Glycerrhicin, or Liquorice-Sugar, C24H3609, is the sweet principle of liquorice. It is a yellow, amorphous powder, having a sweet, acrid taste. It is soluble in water and alcohol. Helleborin, C36H4206, is found together with helleborein in the root of green hellebore. It is insoluble in water, and forms glistening needles. A powerful poison. Indican occurs in all plants yielding indigo, and sometimes in urine, and forms a pale-brown, syrupy liquid, having a bitter taste. The liver is probably the seat of its production in the body, and indol, taken up from the alimentary canal, the ma- terial from which it is produced. When allowed to ferment, or when treated with dilute acids, it forms indigo blue and indi- glucin, a form of sugar. Indican is found in dogs’ urine in greater quantity than in human urine. It also sometimes ap- pears in the sweat. (See Indigotin, Art 625.) Populin, C20H22O8, occurs with salicin, in the bark and leaves of the aspen. It forms small prisms, having a sweet taste. Boiled with barium hydrate, it yields salicin and benzoic acid. Phlorizin, C21H24Oi0 + 2H20, occurs in the root bark of the apple, plum, pear and cherry tree, and is soluble in alcohol. It is soluble in hot water, from which it crystallizes in silky needles having a bitter taste. Boiled with dilute acids, it yields glucose and phloretin. Polychroite, is the coloring matter of saffron, and forms an amorphous, deliquescent, ruby-red mass. Quercitin, or Flavin, C27H28012, occurs in tea, quercitron, sumac, grape vine, catechu, etc. It is slightly soluble in water, soluble in alcohol, and forms small, yellow crystals, which may be partially sublimed in beautiful, yellow needles. It is colored green by Fe2Cl6. Saponin, C32H54018, occurs in quillaia, or soap-tree bark, and other plants. Soluble in water and alcohol. Its solutions behave like soap solutions. It is poisonous, but is sometimes added to soda water to produce a permanent froth. Its dust causes sneezing. GLUCOSIDES. 303 Solanin, C4,H87N016, occurs in sprouted potatoes. It is a glucose alkaloid ; soluble in alcohol, nearly insoluble in water, and forms gurn-like salts. Tannin, or more properly, tannic acids, form a group of bodies found in plants widely distributed. These bodies are sol- uble in water, have an acid reaction, an astringent taste, and form an insoluble compound with gelatin and albumen. They unite with animal skin, forming leather. With ferric salts, they form blue-black or green precipitates. They are used in the prepa- ration of inks, in dyeing and tanning. Tannic, or Gallotannic Acid occurs in oak bark, nutgalls, sumac and some other plants, in considerable quantities. It may be exhausted with a mixture of ether and alcohol. It is an amorphous, shining mass. Ferric salts give with it a bluish- black precipitate (ink), tartar emetic a white one. It precipi- tates starch, gelatin, albumin, and most alkaloids. Its watery solutions decompose when exposed to the air for some time, yielding gallic and ellagic acids. Dilute mineral acids, when boiled with it, give gallic acid and glucose. Gallic Acid, C7H605 (trioxybenzoic acid), occurs in the leaves of the wild vine, mangoes, and in small quantity in gall nuts, from which it can be exhausted with hot water. It may be obtained from tannic acid by boiling with dilute acids or alkalies, or by spontaneous fermentation. Gallic acid crystallizes from water as fine, silky needles, readily soluble in three parts of boiling water, in ether and alcohol. It gives a blue-black precipitate with ferric salts, and reduces the salts of silver, mercury and gold. Its normal salts are perma- nent, but their solutions readily decompose. It has a strong astringent taste, and is used in medicine, in common with tannic, as a haemostatic and astringent. Quinic, or Quinotannic Acid, C7H1206, occurs chiefly in cinchona barks as a salt of quinine, but is also found in the bilberry and coffee bean. It occurs as oblique, rhombic prisms. It is soluble in water. On dry distillation it yields, among other products, benzoic acid and phenol. Other tannins are known, as caffeetannic, of coffee ; quer- cotannic, of oak ; catechutannic, of catechu ; kinotannic, of kino, etc., which vary in properties slightly, according to source. 304 ORGANIC CHEMISTRY. NATURAL FATS AND FIXED OILS. 612. Almost all the fats and fixed oils are compound ethers of glyceryl, C3H5'". They are found in both the animal and vege- table kingdoms. Some are liquid, while others are solid. Some oils remain permanent in the air, like olive oil, while others oxidize and thicken, like linseed and poppy oil. These latter are called siccative, or drying oils. The fats are insoluble in water, difficultly soluble in alcohol, but soluble in ether, petro- leum naphtha, and carbon disulphide. The composition of natural oils has been partially considered while speaking of the fatty acids. So far as known, no fat consists purely of one substance, but of a mixture of oleate, palmitate and stearate of the triad radical, glyceryl. These fats are decomposed by heat; acrolein being one of the products. Stearine, or Stearin, C3H5(C18H3502)3, is found in the more solid fats. It may be separated from the other principles, by melting tallow with turpentine, when the stearin remains in solu- tion, while the olein and palmitin are precipitated. By adding water to the liquid, the stearin may be separated. It fuses at 71° C. (160° F.), and solidifies again at 50° C. (122° F.). Palmitin, C3H5(C1(;H3102)3, is the chief constituent of mutton fat, lard and human fat. It is more soluble in alcohol and ether than stearin. It crystallizes in fine needles, and its melting point is variously stated at 46° C. (115° F.) and 61° to 62° C. (142° to 144° F.). Olein, C3H5(C18H3302)3, is the fluid constituent of most fats and oils. When pure, it is a colorless fluid, becoming' yellow on exposure to the air. It may be obtained from olive oil by treating it with cold alcohol, cooling the solution to 0° C. (32° F.) to separate the palmitin, and adding water to the alcoholic solution to precipitate the olein. Olein is more abundant in vegetable than in animal oils. When treated with hot alkalies or superheated steam, the fats are saponified (see Art. 553). Most fats decompose slowly in contact with air, and become rancid. In the process of digestion they are partially saponified and then emulsified; i. e., broken up into minute drops. The active agents in this change are the bile and pancreatic secretion. The emulsification and absorption of partially saponified fats takes place with greater ease than with pure fat; hence, a slightly rancid oil is more easily assimilated than a fresh one. PROTEIDS. 305 The sources of fat in the human body are, 1st, the fat taken as food ; 2d, the decomposition of proteids; 3d, the carbohydrates, a portion of which is converted into fat in the butyric fermenta- tion in the intestines. 613. Butter consists of a mixture of stearin, palmitin and olein, not soluble in water, and the glycerides of butyric, caproic, caprylic and capric acids. These last acids are soluble and volatile. Oleomargarin, butterine, suine, etc., are artificial mix- tures of butter with foreign fats, made to imitate butter. The principal foreign fats employed are lard, beef oil, cotton seed, sesame and similar oils. The usual method of manu- facture is to melt the foreign fats, deodorize them, when necessary, with nitric acid, then either to mix them with genuine butter, or churn them with milk. The mixture usually has a melting point above or below that of genuine butter. Melting points of various fats :— Butterine, 31.3° C. Cocoa butter, 34.9° C. Butter (average), 35.8° C. Beef dripping, 43.8° C. Veal dripping, 47.7° C. Lard, 42° C. to 45° C. Mutton fat, 50° C. to 51° C. Tallow, 53° C. A low melting point generally indicates butterine, or vegetable oils, while a high one indicates the presence of animal fats. PROTEIDS. 614. This important class of bodies forms the chief part of the solid constituents of blood, muscle, lymph, glands and other organs of animals, and is also found in plants, principally in the seeds. They are the principal substances taking part in the physiological changes in the organism. They are colloid (not crystalline), do not diffuse through animal membranes, and are very prone to putrefaction. No accurate formulae have been found for them. They all contain carbon, hydrogen, nitrogen and oxygen, while most of them contain sulphur in addition, and all contain some ash, mostly in the form of calcium phosphate. Independent of the ash, they have the following composition:— ALBUMINOUS COMPOUNDS. Carbon, 52 to 54 per cent. Hydrogen, 7 to 7.3 “ Nitrogen, 13 to 16 “ Oxygen, 21 to 26 “ Sulphur, 1 to 1.6 “ 306 ORGANIC CHEMISTRY. Theproteids are decomposed by heating with aqueous solutions of acids and alkalies, and with oxidizing agents. When heated dry, they decompose, furnishing ammonia and compound ammonias. They all dissolve in strong acetic, hydro- chloric and phosphoric acids, and in alkalies. When boiled with hydrochloric acid, in contact with air, the solution assumes a blue color, changing to brown. On heating with a solution of mercurous nitrate containing nitrous acid, they assume a fine red color, and the same color is produced by the joint action of a solution of sugar and sulphuric acid. When exposed to the air in a moist state, they rapidly putrefy, producing ammonia, ammonium sulphide, carbon dioxide, lactic, butyric, and other fatty acids, amines, leucin, tyrosin, etc. ALBUMINS. 615. Serum Albumin exists in blood, chyle, lymph, and in small quantity in milk. In certain renal diseases, it appears in the urine. When its solutions are heated to about 72° C. (161.6° F.), it coagulates to a flocculent precipitate, which, when dried, forms a compact mass. Its solutions have a specific rotary power of —56°. Strong min- eral acids first precipitate it, then dissolve the coagulum. It is not precipitated by acetic acid alone, but when acidified with this acid, potassium ferrocyanide and ferricyanide coagulate it. The following reagents may be used to detect its presence in solution ; citric or acetic acid with potassium ferrocyanide, potas- sio-mereuric iodide, mercuric chloride, picric acid, concentrated nitric acid, or trichloracetic acid. Egg Albumin is found in the white of eggs, and differs from the above in being almost insoluble in nitric and hydrochloric acids, and is precipitated by ether. Its specific rotary power is less than that of serum albumin, being —35.5°. Vegetable Albumin occurs in small quantity in most vege- table juices. It shows the same general properties as the other albumins. THE GLOBULINS. 616. The globulins differ from the albumins in being insolu- ble in water, but soluble in sodium chloride solution (1 per cent.). Except vitellin, they are precipitated by saturated solutions of the same salt. Soluble in very dilute HC1 (1 part in 1000 being sufficient), with production of syntonin. THE GLOBULINS. 307 Vitellin occurs in yolk of egg. A white, granular body, sol- uble in dilute NaCl solutions, and not precipitated by a saturated solution of the same. It coagulates at about 70° C. (158° F.). Dissolves readily in dilute acid (TV per cent.) and in alkalies; it is precipitated by alcohol. Globulin or Crystallin, occurs in blood, chyle, lymph, serous fluids, and the crystalline lens. In many of these fluids it exists in’ large quantity, and these coagulate spontaneously when removed from the living body, forming fibrin—probably by the combination of two modified forms of globulin called fibrinogen and fibrinoplastin. Globulin is not precipitated by a saturated solution of NaCI, but is precipitated by alco- hol, or by carbonic anhydride allowed to bubble through the liquid. Closely allied to globulin are two substances found in animal fluids; viz. fibrinogen and fibrinoplastin or paraglobulin. Fibrinogen is found in blood, chyle, lymph, and in serous fluids, but especially in hydrocele and pericardial effusions. Fibrinoplastin is met with in the serum of blood after coagu- lation, in white corpuscles, lymph, chyle, pus, connective tissue and the cornea. These bodies are soluble in acetic acid, dilute alkalies, alkaline carbonates, and neutral saline solutions; but are precipitated from solutions by a current of carbon dioxide and very dilute acetic acid (TV per cent.) The neutral solutions of these bodies, when mixed in presence of a special ferment, form fibrin. This is supposed to explain the coagulation of blood, etc. Some authors claim that fibrinogen alone, with a soluble ferment, is concerned in the production of fibrin. These generators of fibrin are prob- ably all derived from the white corpuscles. Myosin, or muscle fibrin, is intermediate between globulin and fibrin. It is the name given to the solid which separates in the coagulation of muscle plasma, and forms an elastic gelatinous mass. Muscle juice, free from blood, is a yellowish, opalescent, syrupy, faintly alkaline liquid, coagulating at ordinary temper- atures. The clot is called myosin. Syntonin is easily prepared by treating myosin with a very small quantity of HC1. Fibrin is a white, elastic, more or less fibrillated solid, insolu- ble in water or dilute salt solution. Soluble in acids (1 to 5 per cent.) with difficulty. With strong hydrochloric acid, it forms a violet solution. When boiled with caustic alkaline solutions, it forms ammonia and alkaline sulphides. It forms a blue color 308 ORGANIC CHEMISTRY. with hydric peroxide, or partially oxidized oil of turpentine, and freshly prepared tincture of guaiacum. Fibrin may be prepared by whipping blood with a bundle of twigs, and wash- ing the coagulum with water and then with alcohol and ether. HEMOGLOBINS. 617. The haemoglobins, or blood pigments, form the chief constituent of red blood corpuscles in vertebrates, and occur in the muscle of mammals, and in the blood of a few of the inverte- brates. They all crystallize, but not with equal facility. All haemoglobins are of a blood-red or brick-red color when in pow- der. They contain from .4 to .6 per cent, of iron, and differ slightly in composition. The crystalline forms of haemoglobins differ in different ani- mals. The crystalline blood pigments are oxyhsemoglobins. Haemoglobin forms a feeble compound with oxygen, which it releases by heating its solutions in a vacuum or in presence of ferrous sulphate, ammonium sulphide, stannous chloride, etc. Reduced haemoglobin and oxyhaemoglobin are distinguished by their absorption spectra, the latter showing two such bands sepa- rated by a green band, while the former shows but one broad band occupying nearly the position occupied by the greenish- yellow band between the dark bands above mentioned. (See Figs. 10 and 11, Frontispiece). Haemoglobin unites with nitric oxide, carbon monoxide, hydrochloric acid, etc. Some of these compounds give peculiar spectra; they are not easily expelled by oxygen, and hence are deadly poisons when inhaled. Haematin, C34H34N4Fe05, is obtained in the form of a salt, by the decomposition of oxyhaemoglobin with an acid. It is an amorphous, blue-black mass, with a metallic lustre, insoluble in water or alcohol, but soluble in alkalies. It yields two different spectra; one with oxygen, and another with carbon dioxide. Haematin Hydrochloride, or haemin crystals, may be obtained by heating haemoglobin or dried blood with common salt and glacial acetic acid. It forms thin, rhombic plates, having a brown-red color. The formation of these blood crystals is used to detect blood stains in criminal cases. The drop of dried blood is placed upon a microscopic slide, together with some pul- verized common salt, and then treated with glacial acetic acid, and a cover glass placed upon it. Heat the slide until bubbles appear in the acid, cool, and examine with a Finch objective. The presence of blood is indicated by the presence of the crystals. ALBUMINATES. 309 ALBUMINATES (Derived Albumins). 618. There are two forms of these compounds, the acid albu- minate and alkali albuminate. They are obtained by dis- solving albumin in acids or alkalies. Some of the acid albumins contain sulphur, while the alkali albumins do not. When freshly prepared, they are soluble in dilute acids, alkalies, and alkaline carbonates, and their solutions are precipitated by careful neu- tralization, but not by boiling, and with difficulty by alcohol. Alkali albumin occurs in blood cells and blood serum, chyle, pancreatic, nervous and corneal tissues, and in the crystalline lens. It closely resembles casein. Acid Albumin, Syntonin, or Albumose.—Some authors limit the term acid albumin to the acetic acid compound, and syntonin to the hydrochloric acid compound, the first result of the action of gastric juice upon albumin. This distinction seems likely to confuse, and is, at least, unnecessary. Acid albumin, when pure, is a white, gelatinous mass, insoluble in water or salt solutions, but soluble in very dilute hydrochloric acid or caustic alkalies, and its solutions are not precipitated by boiling wTith water alone, but are coagulated by boiling with solutions of magnesium sulphate, strong salt solutions, alum, and many other metallic salts. Pure nitric acid gives a precipitate with its solu- tions. Casein is a natural alkali albuminate found in milk of mam- mals, and differs only in some slight particulars from that found in blood, muscle, etc. Casein exists in milk in the soluble form or in a state of semi- solubility. Under a high magnifying power the casein can usu- ally be seen as a very finely granular solid, and therefore a portion of it, at least, must be in suspension, instead of in actual solution. There is a slight difference in the composition and properties of casein of cow’s and of human milk, which explains a part of the difference in digestibility of the two. The former is more soluble in water and alcohol than the latter. Casein is somewhat richer in nitrogen than alkali albumin ; it yields sul- phur to heated potassium hydrate, which alkali albumin does not. It is coagulated by rennet, which is not the case with alkali albumin. Its solutions do not coagulate on boiling, are precipi- tated by most acids, but not by simple neutralization in presence of an alkaline phosphate. Potassium ferro-and ferri-cyanides, and dilute sulphuric acid precipitate casein in presence of free acetic acid. Rennet contains a special curdling ferment, as also 310 ORGANIC CHEMISTRY. do gastric and pancreatic juices, which can precipitate casein in alkaline solutions at slightly elevated temperatures. Vegetable Caseins.—Legumin occurs in the leguminous plants, as an alkali albuminate. It may be obtained from softened peas, beans, etc. It resembles casein in its properties. It dissolves in dilute alkalies and acids, and when the albuminate solution is boiled, it forms a pellicle like milk. Conglutin resembles legumin, and is found in almonds, kernels of most stone fruits and lupins. Gluten fibrin occurs with other pro- teids in most of the cereal grains. Gluten, so called, is a mixture of several proteid substances. Gluten fibrin is insoluble in water and strong alcohol, but soluble in alcohol containing acetic or tartaric acid. Soluble in dilute acids and alkalies. Boiling water and salts coagulate it. Mucedin, and gliadin, are the gluten constituents soluble in alcohol. PEPTONES. 619. The gastric, pancreatic, and probably the intestinal juices convert albuminous bodies into a more soluble and dif- fusible form, called peptones. Several different peptones have been described, but some of them are probably mixtures of par- tially peptonized albuminoids and true peptone; since the con- version is a gradual process of hydration, it is but natural to ex- pect such a mixture. Dehydrating agents or simple heat can reverse the process, and convert peptone into albumin. It seems certain that the first action of gastric juice is to produce two bodies closely resembling, if not identical with syntonine (acid albumin). These are further changed into two kinds of peptone, named by Kiihne hemipeptone and antipeptone. The reactions of peptones are mostly negative. Solutions of pep- tone do not exhibit a viscid character, are not coagulated by heat, nitric acid, or acetic acid and potassium ferrocyanide. Alcohol precipitates it, but the precipitate is soluble in water. Tannin, mercuric chloride, picric acid, and potassio-mercuric iodide and acetic acid precipitate it. The most marked property is its extreme solubility in water, and its ready diffusibility through animal membranes. Amyloid matter is not converted into peptone by pepsin or trypsin. Lardacein, or Amyloid Matter is an amorphous, friable mass, occurring in certain regions of the body as a pathological product. It seems to be a derivative of fibrin. It is generally found as little transparent grains, or corpuscles, somewhat resem- THE COLLAGENS. 311 bling starch granules. The most usual locations are the liver, spleen and kidneys. It gives many of the proteid reactions. It is stained a reddish-brown color with iodine, which is changed to a violet or blue tint by dilute sulphuric acid. Aniline violet stains it rose-red or violet instead of blue. Eosin stains it a bright red color. 620. Collagen is the name given to the substance composing white, elastic tissue of the skin, tendons, etc. When boiled for some hours with water, it forms gelatin. Collagen and ossein seem to be closely allied in both composition and properties. Embryonic tissues when boiled, yield mucin and chondrin instead of gelatin. Ossein is the proteid basis of bones, and is converted into gelatin by boiling with water. Gelatin in the pure state is a colorless or slightly yellowish, transparent, vitreous, tasteless mass. It swells in cold water, and readily dissolves in hot water or glycerine, forming a thick, viscid" solution, which sets or gelatinizes on cooling. Heating to 140° C. (284° F.) or long continued boiling destroys this power of gelatinizing. It is soluble in dilute acetic and other acids, but insoluble in alcohol, ether and oils. Solutions of gelatin dissolve copper oxide with a blue color, which, on boil- ing, is reduced, but without separation of red oxide ; it therefore interferes with the copper test for glucose. An impure gelatin or glutin prepared from animal refuse (bones, hides, etc.), when in the dry state, forms glue. Liquid glue is a solution of glue in acetic acid. Solutions of gelatin are precipitated by tannic acid, mercuric chloride, alcohol, and chlorine water, but not with acetic acid and potassium ferrocyanide, alum, or acetate of lead. Gelatin is lsevogyratory. Chondrin exists in permanent cartilages, and forms gelatin on boiling with water. The gelatin from this source differs slightly from that obtained from collagen, or ossein. Mucin occurs in the cement substance of connective and epithelial tissues. It is also present in bile, and secretions of mucous membranes. To prepare it from bile, precipitate with alcohol, dissolve in lime water, precipitate again with acetic acid, filter, and wash with alcohol or ether. It swells up in a little water, and dis- solves in a large quantity. Its solutions do not coagulate on heating, and it contains no sulphur. It is insoluble in alcohol, ether, chloroform, or gastric juice. THE COLLAGENS. 312 ORGANIC CHEMISTRY. Its solutions are precipitated by acetic acid, alum, basic acetate (sub-acetate) of lead, and very dilute mineral acids. Its solu- tions dissolve oxide of copper, and thus hinder the copper test for sugar. BILIARY COMPOUNDS. 621. Bile contains a number of peculiar compounds, some of which occur in other animal secretions. The three important classes of constituents are the acids, the biliary pigments, and cholesterin. In addition, we find lecithin, cholin, fats, soaps, mucus, a diastatic ferment, and inorganic salts. For analysis of human bile, see Appendix. The bile of other animals contain some other ingredients not mentioned there, as hyoglycocholic acid, found in the bile of the pig, lithofellic acid, found in the bile of antelopes, kya- nuric acid, found in the urine of dogs, and lithuric acid, found in calculi sometimes voided by oxen. Glycocholic acid, C26H43N06, occurs in bile as a sodium salt. The acid occurs in two forms, the one as fine crystalline needles, and the other as an amorphous resinous solid. It is monobasic. It is soluble in hydro- chloric, sulphuric and acetic acids without decomposition. Sol- uble in glycerine, slightly soluble in cold and readily in hot water. Very soluble in alcohol and insoluble in ether. When boiled with alkalies or mineral acids, it splits up into cholic acid and glycocin. Taurocholic acid, C26H45NS07, occurs in small quantity in human bile, but in larger quantity in that of the carnivora. It is soluble in water and alcohol. With boiling alkaline or acid solutions it forms cholic acid and taurin. The spontaneous decomposition of bile causes the same change. Tests for Biliary Acids.—To a solution of the biliary acids add a few drops of a solution of cane sugar (1 to 10), and then strong sulphuric acid. A cherry red, followed by a deep purple violet color is produced. This test, known as Pettenkofer’s, can- not be applied to organic mixtures, as urine, because numerous other bodies give the same color. To apply it to such mixtures, evaporate to dryness, exhaust with absolute alcohol, decolorize with animal charcoal, evaporate to dryness, treat with water, and then test as above. 621. Cholesterin, G26H440, may be obtained from the hot alcoholic solution of bile solids. It forms characteristic, glisten- ing, rhombic plates, with notched edges or corners. It may be regarded as an alcohol, and forms a series of ethereal salts with BILIARY COMPOUNDS. 313 acids. It is soluble in benzol, chloroform, hot water, ether, and hot alcohol. Insoluble in cold water. Heated with nitric acid, it gives off yellow acid fumes and forms cholesteric acid, C8H10O5. Cholesterin forms the chief portion of biliary calculi; it is also found in blood, nervous tissue, the brain, yolk of eggs, and in the seeds of some plants. Tests.—Cholesterin may be recognized : 1st, by the crystal- line form under the microscope; 2d, when moistened with strong nitric acid, and evaporated to dryness, a yellow residue remains, which turns to a brick red on adding ammonia; 3d, on warming with dilute sulphuric acid, and then adding a drop of strong sul- phuric acid it turns deep red in color. The solution in chloroform, when shaken with an equal volume of strong sulphuric acid, forms a blood-red solution. 623. Biliary Coloring Matters.—There are at least four pigments obtainable from bile and biliary calculi, viz.: biliru- bin, biliverdin, bilifuscin and biliprasin. Bilihumin and hydrobilirubin have also been described. The principal one of these, and probably the only one contained in bile when first secreted, is bilirubin, from which the others are derivatives. Bilirubin, C16H18N203, is met, in the free state, in the bile of man and the carnivora, and ox bile; also, in combination with calcium, in biliary calculi. It is probably identical Avith the red crystalline matter of old hemorrhagic clots, called hematoidin, and with biliphaein, bilifulvin and cholepyrrhin. It may be prepared by treating the powdered biliary calculus first with ether, then with boiling water slightly acidified with hydrochloric acid. The residue is washed with pure water, and dissolved in hot chloroform and filtered; from the filtrate the chloroform is distilled off and the residue treated with absolute alcohol and ether, by which the bilifuscin is removed and bili- rubin left. By dissolving in chloroform and setting aside, a part of it may be obtained as a dark red crystalline powder. It also exists as an orange red, amorphous powder. It acts the part of a weak acid, combining with sodium, cal- cium, barium, lead, etc. Formula of the calcium salt, (C16HI7N2 03).2Ca. Bilirubin is closely related to hsematin, a derivative of haemo- globin. This is its probable source. 3C32H36N4Fe06 + 30 = 6C16H18N203 + 3Fe0 (?) Moderately strong nitric acid, added to an aramoniacal solution 314 ORGANIC CHEMISTRY. of bilirubin, first colors it green, then blue (bilicyanin), violet red and finally yellow. (Gmelin’s test for bile.) Nearly the same series of colors are produced by adding bromine to the chloroform solution, with the exception that it finally becomes colorless. Nascent hydrogen converts it into hydrobilirubin, C32H44N407, (urobilin of urine, stercobilin of faeces.) Hydro- bilirubin is a dark brown amorphous powder, soluble in alkalies, sulphuric and acetic acids, alcohol, ether and chloroform. It does not give the play of colors with nitric acid. It is probably formed in the feces by the action of the nascent hydrogen, set free by the butyric and putrefactive fermentations, upon bili- rubin. Biliverdin, C16H20N2O5 (or C16H18N204), is an oxidation pro- duct of bilirubin, and is readily formed by exposing alkaline solutions of this pigment to the air, or by similar treatment of fresh bile. It forms a green, amorphous powder, insoluble in water, ether and chloroform. It is soluble in alcohol, acetic acid and alkaline solutions, and reacts with nitric acid as does bili- rubin. Hydrobilirubin may be prepared from it. Biliprasin, C16H22N206, is found in human gall stones, and bilifuscin, C1BH20N2O4, occurs in small quantities in old bile, and in gall stones. According to Stadeler, biliverdin is bilirubin -j- 0 and H20. Biliprasin is biliverdin + H20% Bilifuscin is bilirubin -f- H20. Viewed in this light these various pigments would appear to be formed in the following order : Haemoglobin, hsema- tin or hsemotoidin, bilirubin, hydrobilirubin (urobilin or uroch- rome and stercobilin), bilifuscin, biliverdin, biliprasin. 624. Urinary Pigments.—Besides urobilin, the urine con- tains at least one, and possibly more, coloring matters. Uroxan- thin or indigogen, is a normal constituent of urine, but is much increased in the first stage of cholera, and in carcinoma of the liver. According to some authors, this coloring matter is iden- tical with indican. Uroxanthin maybe detected in urine by adding to the urine its own volume of hydrochloric acid and a few drops of a solution of chloride of lime ; the solution is colored red, violet, green, or blue, according to the amount of uroxanthin present. In some cases this test succeeds with hydrochloric acid alone. In some cases the urine containing uroxanthin becomes blue, on standing for some days, from the spontaneous putrefaction. Urobilin maybe detected in fever urines by making them alkaline with ammonia, filtering, and adding a few drops of zinc chloride solution, when it will show a green fluorescence. This 315 urobilin reaction may be obtained more distinctly by shaking the urine with ether, separating the ethereal solution, and, after evaporating the ether, dissolving the pigment in absolute alcohol. This solution will usually show the green fluorescence. Uro- chrome (Thudichum) uromelanin (Thudichum) uroerythrin and other pigments have been described, but the whole subject is enveloped in much uncertainty and confusion. Black urine is occasionally seen after breathing arseniuretted hydrogen, in carbolic acid poisoning, and after inunctions of tar. Melanin (Melanogen), is the black pigment of the choroid, melanotic tumors, and skin of the negro. Pathologically, it is found in the urine of persons suffering with melanotic cancer, and sometimes with malaria. It is sometimes deposited in the lungs. Urine containing melanin turns dark on exposure to the air, or, more rapidly, with oxidizing agents, as nitric or chromic acids. Its detection is useful to the physician, as an aid to the diagnosis of melanotic cancer of liver, etc. IMPORTANT VEGETABLE COLORING MATTERS. IMPORTANT VEGETABLE COLORING MAT- TERS. 625. Indigo is a blue coloring matter derived from several species of Iadigofera, and other plants growing in India, Africa and South America. It exists as a glucoside, called indican, which is extracted with water ; the liquid allowed to ferment in the air deposits the indigo as a blue powder. Com- mercial indigo is a mixture of several bodies, containing about 50 per cent, of indigo-blue or indigotin, C16H10N2O2. Indigotin has a deep blue color, with a purple tinge; it is insoluble in water, alcohol, dilute acids and alkalies, but soluble in boiling aniline, and in Nordhausen sulphuric acid, forming indigotinsulphonic or sulphopurpuric acid, C16H9N202 SO:jH. On neutralizing this solution with potassium or sodium carbonate, a blue precipitate of the potassium or sodium salt is obtained. These salts are insoluble in common salt solutions but soluble in pure water, and are met with in commerce under the name of “ indigo carmine” or “indigo extract.” The aqueous solution of these salts, is used as a test for glucose in urine. In- digotin sublimes when heated, the vapor condensing into blue crystals. Reducing agents convert indigo-blue to indigo-white, or hydro-indigotin, Ci6H12N202, which in the moist state oxidizes to indigo-blue. In dyeing with indigo, the goods are steeped in 316 ORGANIC CHEMISTRY. indigo-white, and then exposed to the air, when indigo blue is deposited in the cloth. Indigotin has been prepared synthe- tically. Litmus is a purplish-blue coloring matter obtained from lichens; generally from Lecanora tartarea, by steeping in urine, adding lime and potassium carbonate. The mixture is exposed to the air for a few weeks, with frequent stirring, when a thick, blue solution is obtained. This solution is thickened up with plaster-of-Paris or chalk, formed into cakes, and cut into little cubes. The coloring matter of litmus is a weak acid, forming salts having a blue color, the commercial product being the potassium salt. With acids it becomes red, from the liberation of the acid. Turmeric is the root of Cucurma longa ; it yields a yellow tincture, which turns brown with alkalies. It is used to a large extent to give a yellow color to various articles of food, as mustard, chow-chow, vermicelli, etc Saffron is the stigmas of the flower of Crocus sativa. It yields to dilute alcohol a yellow coloring matter called polychroit or crocin. Tinctura croci is officinal (U. S. P.). Saffron is used to color certain articles of food, as butter, cheese, etc. Annatto is a yellow color, obtained from the seeds of Bixa orellana. It is used in coloring butter, milk, cheese, etc. Logwood, the wood of Hematoxylon, contains a purple dye, hematoxylin, used for purple and black dyes. It is officinal, and is used as a tonic and astringent. Brazil wood furnishes red dyes and lakes. Cochineal, the female of the insect Coccus cacti yields to boiling water and alcohol, a beautiful, red color- ing matter, which, precipitated with alum and an alkaline carbo- nate, yields carmine. Chlorophyll is the name given to the green coloring matters of the leaves of plants. It occurs as microscopic granules distributed through the cell protoplasm in all the green portions of the plant. It may be extracted with alcohol, ether and benzol. Very little is known of this body, but it seems to be composed of two coloring matters, a blue and a green. It contains iron, and is supposed to possess the power, under the influence of sunlight, of decomposing C02 and uniting the carbon to the ele- ments of water. The yellow color of autumn leaves, is due to xanthophyll, an oxidation product of chlorophyll. COMPOUNDS OF ANIMAL ORIGIN. 317 COMPOUNDS OF ANIMAL ORIGIN NOT OTHERWISE CLASSIFIED. 626. Leucin, C6H10(NH4)2Oa (Amido-caproic acid) is found in various organs, intestinal contents, and sometimes in the urine, especially in yellow atrophy of the liver. It may be obtained by pancreatic digestion of albuminous matters, or by treating horn shavings with dilute sulphuric acid. It is a white, crystalline solid, forming shining plates, soluble in water. It unites with both acids and bases. Tyrosin, C9HnN03, is formed at the same time with leucin, and the two usually occur together. It crystallizes in fine needles, which aggregate into sheaf-like bundles or radiating spherical masses. It is but slightly soluble in cold water, and unites with both acids and bases. Lecithin, C44H90NPO9, is an amorphous, waxy substance, very hygroscopic, soluble in alcohol and ether. It is found in nerve tissue, especially the gray variety, in yolk of egg, semen, blood, milk, bile, etc. It plays the part of a fatty body. It is unstable, and is decomposed by boiling alkalies into glycerin- phosphoric, oleic, palmitic and stearic acids, neurin, etc. Protagon, or Cerebrote, C16oH308N5P035 (Gamgee), forms the principal part of the white substance of Schwann. It is a glucoside, and lecithin is one of its decomposition products. It is insoluble, but swells up in water, and is soluble in warm alcohol, from which it crystallizes in fine needles. Thudichum has recently described a number of other phos- phorized substances obtainable from brain tissue, which he classi- fies under two heads as kephalins and myelins. Also a large number of other products, of which little is known. Kreatin, C4H9N3O2, is a weak base, forming crystalline salts with several acids. It forms colorless, transparent prisms, spar- ingly soluble in cold and moderately soluble in hot water. It is found in muscles, Liebig’s extract of meat, and in urine. It is undoubtedly an antecedent of urea. Kreatinin is formed from kreatin by dehydration, and is usually found with the latter. • It is a strong base. Xanthin, C5H4N4O2, is met with in the spleen, muscles, pan- creas, liver and urine. It seems to be an antecedent of uric acid. It forms white scales, sometimes depositing from urine as minute lemon-shaped plates. It is nearly insoluble in water, but soluble in dilute acids and alkalies. It is sometimes found in urinary calculi. 318 ORGANIC CHEMISTRY. Hypoxanthin, C5H4N40 (sarkin), is a white crystalline powder, found in the spleen, thymus, muscular tissue, medulla of bones, urine, etc. Allantoin, Carnin and Guanin are allied to the last two bodies, all being compound ureas. 627. The soluble or unorganized ferments, or enzymes, are a class of albuminoid bodies which have the power, under favorable circumstances, of causing certain chemical changes in other bodies with which they are brought in contact, without themselves undergoing any change. They are called ferments because of the similarity of their action to that of yeast and other well-known ferments. Some of these bodies are of vege- table, while others are of animal origin. Those of vegetable origin are diastase, emulsin and myrosin; while those of animal origin are ptyalin (salivary diastase), pepsin, curdling ferment, pancreatic diastase, trypsin, invertin, emulsin ferment, histozym, and probably others. The exact chemical composition of these bodies is unknown, except that they are proteids. They are all soluble in water, are precipitated by alcohol and by lead acetate. They are very diffusible, lose their activity by being boiled with water, but are not precipitated. They have not yet been obtained in a state of absolute purity. Their action seems to be purely physiological, and not chemical. They impart nothing to or take nothing from the bodies they act upon. Diastase, or Maltin, is the ferment formed from the glu- ten in the cereal grains at the time of sprouting Its chief object is the conversion of starch into dextrin and maltose. Ptyalin of saliva, and pancreatic diastase, if not identical with vegetable diastase, act in exactly the same way. They all act upon cooked starch with great rapidity, but have a very slow action upon unchanged starch. The process is one of hydration, and the action is similar to that which takes place when dilute sulphuric acid is boiled with starch or cellulose. When water is added to H2S04 it probably forms H606S, (H2S04.2H20) or orthosul- phuric acid. This acid, when boiled, tends to part with a por- tion of its water, and if starch or other easily hydrated compound be present, it imparts this water to that body, in the nascent state, so to speak. Diastase acts upon the starch in the cold in the same way that H6S06 does at a higher temperature. The first effect is to thoroughly liquefy the starch, then convert it into dextrin, and finally the dextrin into maltose. ALBUMINOID OR SOLUBLE FERMENTS. ALBUMINOID OR SOLUBLE FERMENTS. 319 The amount of starch that a given weight of diastase can thus transform is variously stated at from 2000 to 100,000 times its own weight, which, however, seems to be a fixed quantity with any given specimen of diastase. The rapidity of its action seems to depend upon the relative proportions of starch and ferment present. When the ferment is present in large quantity, the action is very rapid, almost instantaneous; while if it is small in proportion to the starch, it is slower in action. Diastatic ferment does not exist in the saliva and pancreatic juice of in- fants, previous to the sixth or seventh month, in sufficient quantity to digest much starch. Emulsin or Synaptase occurs in sweet and bitter almonds. It may be extracted by digesting the almonds, freed from fat by pressure, for several hours Avith water. The filtered liquid is acidified with acetic acid, to precipitate conglutin, and the emulsin is then thrown down with alcohol, filtered off, washed with alcohol and dried. It is a white, friable mass, soluble in water, and capable of converting large quantities of amygdalin into sugar, prussic acid and benzoic aldehyde; it also converts salicin into sugar and saligenin. Its aqueous solution readily decomposes, yielding lactic acid. Myrosin is the ferment of mustard. Pepsin contained in gastric juice, is secreted by the glands of the stomach. It may be separated from the other constituents of filtered gastric juice by dialysis, as it does not diffuse through membranes. It is readily prepared by digesting the mucous membrane of the pyloric end of the stomach of the pig, first with strong alcohol, and after twenty-four hours expelling the alcohol by pressure, and digesting for some days Avith glycerin, slightly acidified with hydrochloric acid. Filter through muslin, then through paper, precipitate the pepsin Avith absolute alcohol, col- lect on a filter and dry. Other methods are in use. Pepsin is a yellowish or grayish-white poAvder, soluble in Avater and glycerin, but insoluble in water. It gives none of the albumin reactions, and is precipitated by the acetates of lead. When dry, it may be heated to 110° C. (230° F.) Avithout losing its activity, but its solutions lose it at a much loAver temperature. Its activity is greatest at about 37° C. (98.6° F.), and requires hydrochloric, phosphoric, lactic or other dilute acid to develop its peculiar action. The presence of 0.1 per cent, of NaCl favors its action, but more than 0.5 per cent, hinders its action. Ad- mixture of bile, carbolic acid, or excess of alcohol retard or entirely prevent its action. The acid of gastric juice is mostly 320 ORGANIC CHEMISTRY. hydrochloric daring the intervals of digestion, but during diges- tion several organic acids are set free by the hydrochloric acid from the acetates, malates, tartrates, etc., taken with the food, so that the real work of the digestion is accomplished with the aid of various organic acids instead of hydrochloric alone. The specific action of pepsin is the change of proteids, whether coagu- lated or not, into syntonins and, finally, peptones. Pepsin is scarcely altered by putrefaction. Trypsin occurs in the pancreatic juice, and may be extracted from the pancreas by the process described above for pepsin. Thus prepared, pancreatin is a yellowish-white amorphous pow- der, soluble in water and glycerin, but precipitated by alcohol. It possesses the property of acting upon the proteids in a way somewhat similar to pepsin, but is active only in alkaline solu- tions. It also converts starch into sugar, emulsifies and partially saponifies the fats, and curdles casein. A part of the peptone at first formed by the pancreatic juice, is afterward converted into tyrosin and leucin. The digestion of the proteids is thus begun in the stomach, in an acid medium, and finished in the small intestine, in an alkaline medium. There is this difference, in the two processes, that while acid pepsin readily liquefies the proteid bodies, it does not completely- convert them into peptones; this completion of the process is more quickly and completely done by the trypsin. Invertin is a ferment existing in the intestinal juices, which has the power of inverting cane sugar; i. e., it converts it into dextrose and Isevulose. Of its composition and other properties little is known. Invertin, or a substance possessing the same property, as well as a diastatic ferment, is found in the liquid portion of bakers’ or brewers’ yeast. Histozym is a soluble ferment, supposed to exist in the blood, liver and kidneys, and which has the power of causing a variety of reactions within the body, such as the conversion of benzoic acid into hippuric acid, etc. Some authors have described certain other ferments under the name of microzimas, which act as active chemical and physio- logical agents in the body during life, and cause its decomposition after death. They appear as minute molecular granulations, and are regarded as a part of the living organism by some, and as distinct organized ferments by others. ORGANIZED FERMENTS. 321 ORGANIZED FERMENTS. 628.. Somewhat similar in action to the preceding group of ferments are certain forms of low vegetable organisms, which are known as organized ferments. These organisms vegetate most readily at temperatures of from 20° C. (68° F.) to about 40° C. (104° F.). Temperatures above or below these limits retard their growth, while a temperature near the boiling point entirely destroys their activity. A very minute quantity of any of these ferments can grow and exert its peculiar action as long as its peculiar nourishment lasts. Organized ferments excite chemical changes as the direct physiological result of their growth. They are all killed by hydrogen peroxide, and the chemical change is stopped by it. Borax stops the action of soluble or albuminoid ferments. All physiological fermentations in the organism are caused by the soluble ferments, while patho- logical fermentations are caused by the organized ferments. The most important of the ferments of this class are yeast, or alcoholic ferment, acetic acid ferment, lactic, butyric and putre- factive ferments. With the exception of the first of these organ- isms, they all belong to the bacteria family. Yeast (Torula, or Saccharomyces cerevisise) consists of one-celled, globular or oval-shaped plants, multiplying by budding. There are several varieties of this fungus. The prin- cipal action caused by yeast in saccharine fluids is, first, to convert the saccharose into grape sugar, and then change this into alcohol, carbon dioxide, and a trace of succinic acid and glycerin. The spores of yeast are always to be found either in the air or upon the surface of fruit, whence they find their way into the solutions made from their juices, which explains the apparent spontaneous fermentation. Acetic acid ferment (mycoderma aceti) occurs usually in the form of chains of very small globular bodies, formed by multiplication of the cells by divisions, at right angles to the line of growth. It belongs to the bacteria family. It grows in alco- holic solutions containing a small amount of albuminous matter or ammoniacal salts, and alkaline and earthy phosphates. A little acetic acid favors its growth, as well as a free supply of air. It acts by causing an oxidation of the alcohol to acetic acid; when this change is complete, the ferment dies for want of nourishment. Saccharomycetes Albicans (Oidium Albicans) is the ferment which is found growing upon the mucous membrane of 322 ORGANIC CHEMISTRY. the mouth of infants, producing the disease known as “thrush” or “sprue.” The fungus appears as white patches upon the tongue and other parts of the mouth. The cells are globular, oval, or cylindrical, and occur in colonies or rows. It excites alcoholic fermentation, but feebly. Lactic and butyric fermentations go hand in hand, the first usually, if not always, preceding the latter. They require a neutral or alkaline medium for their development, and.grow best without oxygen, at a temperature of 85° C. to 40° C. (95° F. to 104° F.). These conditions exist in the intestines, and they are always found there. The subtances most prone to these ferment- ations are sugars, organic acids, soluble proteids, and especially mucus. The products of the fermentation are-lactic, acetic and butyric acids, carbon dioxide and free hydrogen. These gases distend the bowel and often produce colic. Any excessive pro- duction of mucus in the bowel greatly favors these fermentations. Putrefactive fermentation is caused by the growth of various forms of bacteria. The proteids are most liable to putrid fermentation, splitting up into fats, tyrosin, leucin, ammonia, sulphuretted hydrogen, carbon dioxide, hydrogen and nitrogen. This fermentation takes place in all organic infusions containing proteid matters, when exposed to the air; it also occurs in the small intestine in cases of constipation, or in some forms of indigestion, and to a slight extent in the normal condition. POISONS AND THEIR ANTIDOTES. 629. Of the emergencies which arise in every-day life, or even in the practice of the young physician, none are more embar- rassing than acute poisoning. The word poison, to many people, carries with it an idea of horror and panic. Even the physician is liable to something akin to alarm, when he comes into the presence of a victim of a violent poison. It is for this reason that we introduce a few of the most common poisons, with their anti- dotes. We do not intend to give a guide to the treatment of cases of poisoning, but merely a few simple rules to be remembered, as first aids to those suffering with acute poisoning. 630. The first thing to be considered is, the symptoms of poisoning. . Not unfrequently persons claim to have taken poison, when such is not the case. Or, suspicious friends fear that poison has been taken. The author has often met with cases of this kind, where a knowledge of the symptoms of poisoning has saved the patient a very disagreeable experience, and the POISONS AND THEIR ANTIDOTES. 323 physician a great deal of trouble and future chagrin. The medi- cal jurist should be familiar with the nature and actions of poisons, the symptoms which they produce, the circumstances which re- tard or otherwise modify their action their chemical and physio- logical antidotes, the pathological changes they induce, and the methods of combating these results. It is our purpose, here, to name a few of the symptoms of poisoning, and then to offer a few hints as to antidotal treatment. The chief characteristics of poisoning are, more or less severe symptoms coming on suddenly, or within a few hours after taking some substance or fluid into the stomach, the individual being previously in a state of health. These symptoms usually increase steadily and uniformly, and tend to prove rapidly fatal. The symptoms may be greatly varied as to time and severity, by the quantity or form in which administered, the state of the stomach—whether full or empty—the condition of the person— whether asleep or awake—and a certain idiosyncracy of the individual. The symptoms which should arouse suspicion of acute poisoning are, the sudden onset of pain in the region of the stomach of a healthy person, especially of a “ burning pain,” accompanied by dryness of or a metallic taste in the throat, more or less vomiting, great prostration of the vital powers, a deathly or cadaveric aspect, or an expression of great fear or concern, the rapid intervention of coma, and speedy death. If all, or the greater number of the above symptoms are .present in any case, there is reason for suspicion, and the physician should govern himself accordingly. (See remarks under Arsenic, Art. 244.) Poisons may, for convenience, be divided into the following five classes, based upon their effects upon the human subject: 1st, Corrosives ; 2d, Irritants ; 3d, Neurotics ; 4th, Septic Poisons; 5th, Gaseous Poisons. 631. Corrosive Poisons.—To this class belong those poisons which exert, principally, a local action upon the tissues with which they come in contact. The most important of this class are cor- rosive sublimate (HgCl2), the concentrated mineral acids (sul- phuric, hydrochloric, nitric), and oxalic acid ; the alkalies and their carbonates (potassium, sodium, and ammonium hydrates and carbonates) ; corrosive salts, as bisulphates of the alkaline metals, alum, nitrate of silver, chloride of zinc, butter of anti- mony (SbCI3). Carbolic acid is a violent corrosive, when con- centrated, and also has a remote effect upon the system after being absorbed. The symptoms of corrosive poisoning follow immediately after taking the poison, and are a sense of acid, alka- 324 ORGANIC CHEMISTRY. line, or metallic, burning pain in the mouth, throat, gullet and stomach, usually inducing vomiting, which, however, does not relieve the distress. The pain soon extends over the en- tire abdomen, and is accompanied with symptoms of shock, or collapse. 632. Irritant Poisons.—Irritant poisons give rise to pain in the stomach, of a burning character, usually coming on some minutes or hours after taking the poison. In this respect, they differ in their action from the corrosives. The pain is accom- panied, or followed, by vomiting, faintness, purging and tenesmus ; the evacuations being often tinged with blood. The pulse is weak or irregular, and there is frequently severe headache. Death is usually caused by collapse, convulsions, or by inducing severe inflammations, which wear the patient out, after a variable period of time. Some have, also, a specific physiological action, besides their irritant action. The following are the more com- mon irritants : Dilute mineral acids, concentrated organic acids, lime, zinc, copper, barium, silver and mercuric salts; all coin- pounds of arsenic and antimony ; phosphorus, iodine, bromine, etc. Many kinds of food may, under certain imperfectly under- stood conditions, become irritant poisons. Meat, fish, lobsters, tomatoes, etc., especially after having been canned and then ex- posed to the air. 633. Neurotic Poisons.—The neurotics exercise their ac- tion through the nervous system, and, therefore, only after absorption into the circulation. They rarely exert any local action. The neurotics are sometimes subdivided as follows:— Examples. Narcotics, or those producing sleep Opium. Anaesthetics, or those producing insensibility Chloroform. Inebriants, or those producing intoxication Alcohol. Deliriants, or those producing delirium Hyoscyamus. Convulsives, or those producing spasms Strychnine. Hyposthenisants, or those producing death by syncope Prussic acid. Depressants, or those producing marked depression Nicotine. 634. Septic Poisons.—To this class belong certain poisons introduced into the body through abrasions of the skin, open wounds, or by the fangs or sting of venomous animals or insects. In many respects these poisons resemble, in their action, the de- pressing narcotics. 635. Poisonous Gases.—To this class belong carbon mon- oxide (charcoal fumes), carbon dioxide (choke damp), marsh gas (fire damp), illuminating gas, hydrocarbon vapors, sewer gas, TREATMENT OF ACUTE POISONING. 325 confined air of living apartments* and noxious gases and vapors from manufacturing establishments. TREATMENT OF ACUTE POISONING. 636. In every case of acute poisoning, or where the symptoms and circumstances indicate that a poison has been taken, the first thing to do is to produce vomiting (emesis), or to empty the stomach with the stomach pump. Then combat the local and constitutional effects of the poison by appropriate means. THE PRINCIPAL EMETICS. Zinc Sulphate.—Give 20 grains at once, or, dissolve in two ounces of water, and give tablespoonful every 15 minutes. Copper Sulphate.—5 grains every 15 minutes, or, still better, 10 grains at once, followed by tepid water. Alum.—A tablespoonful, given in syrup or honey. Mustard (ground).—A dessertspoonful, stirred in tepid water and quickly swallowed. Very efficient, and is somewhat stimulating. Apomorphine.—Give grain hypodermically. Syr. Ipecacuanhae.—Used mostly for children. Is depressant, every 15 minutes to a child two years old, until emesis is produced. Tepid Water.—Drink copiously. It may be assisted by tickling the throat with a feather or the extended finger. 637'. Strong Mineral Acids.—Chalk, lime, whitewash, mag- nesia, alkaline carbonates, baking soda, soap. Then give oil freely, and mucilaginous drinks. Oxalic and Tartaric Acids.—Chalk, lime-water, whitewash. After Treatment.—Mucilaginous drinks given freely, stimu- lants well diluted. Alkalies, Caustic and Carbonated.—Vegetable acids, such as vinegar, lemon juice, tartaric or citric acids ; fixed oils, such as castor, linseed, olive or cod-liver oil. Mucilaginous drinks may be given freely. Antimony—Tartar Emetic—Wine of Antimony, or Oxide of Antimony.—Assist the vomiting by draughts of warm water, or mucilaginous drinks, such as flaxseed tea. Then give a cup of strong tea, or an infusion of oak bark, or a solu- tion of tannin. This may be followed by opiates. SPECIAL POISONS AND THEIR ANTIDOTES. 326 ORGANIC CHEMISTRY. Chloride of Antimony.—Magnesia and baking soda. Arsenic—White Arsenic—Arsenious Acid.—Expel the poison by thorough emesis. Promote the sickness by free use of albuminous or mucilaginous drinks. As an antidote, give raw eggs, beaten up in milk, freshly prepared ferric hydrate, solution of dialysed iron, or calcined magnesia, followed by stimulants well diluted. Metallic Salts—Alum.—Alkaline carbonates, baking soda. Soluble Barium Salts.—Soluble sulphates, Epsom or Glau- ber’s salt. Soluble Copper Salts.—Albumin, white of egg and milk, baking soda. Iron—Green Vitriol—Persulphate of Iron.—Baking soda and emetics. Lead—Sugar of Lead, White Lead.—Solution of Epsom or Glauber’s salt, dilute solution .of H2S04. Mercury—Corrosive Sublimate.—Albumin, w'hite of egg and milk, followed by emetics. Silver Nitrate—Lunar Caustic.—Common salt. Zinc Chloride—Soldering Fluid, Burnett’s Fluid.— Baking soda, milk, white of egg, tea, decoction of bark. Give opium to relieve the pain. Tin, Chloride of.—Baking soda, magnesia, milk and white of egg. Iodine—Most common form the tincture.—Give boiled starch paste, made thin enough to drink. In urgent cases, use starch or flour, with cold water. Phosphorus—Rat Poison.—Has no true ‘chemical anti- dote. Magnesia, milk of magnesia, chalk, or lime suspended in gruel, turpentine. Give no fixed oils. Poisonous Meat, Fish, Lobsters, Etc.—Encourage vomiting by copious draughts of water ; counteract depression with diluted brandy or whiskey; relieve pain with opium or one of its preparations. Apply hot fomentations to abdomen. When vomiting ceases, give castor oil or other laxative. Narcotics—Opium, Morphine, Laudanum, Paregoric, Soothing Syrups, Quieting Cordials, Etc.—First empty the stomach of any poison still remaining unabsorbed, by emetics. The patient is to be kept awake by forced walking, by the cold douche, or flagellations with wet towels. Faradaic electricity may be applied to the spine. Give strong coffee in abundance. NEUROTICS. TREATMENT OF ACUTE POISONING. 327 Anaesthetics—Vapors of Chloroform or Ether,Chloral, Methylene Dichloride, Nitrous Oxide, Etc.—Pure air, cold douches, artificial respiration, hypodermic injections of brandy, aquae ammonia (diluted), or nitrite of amyl. Galvanism or Faradism may be employed, if the instruments are at hand. Inebriants—Alcohol, Cocculus Indicus, Nitrobenzol (Essence of Mirbane), Aniline, Etc.—Emetics, when there is reason to believe that any poison remains unabsorbed, then am- monium carbonate, hydrate or acetate. Treat the narcosis as under opium. Prussic Acid (hydrocyanic acid), Potassium Cyanide, Laurel Water, Peach, Cherry, Plum Pits, Etc.—No chemical antidote. Emetics, where there is time. Cold affusions to face and neck, inhalations of ammonia; spirits of ammo- nia should be given internally, with brandy. Aconite.—See Prussic Acid. Digitalis (Foxglove), Calabar Bean (Physostigma), Tobacco (Nicotine), Hemlock (Conium), Lobelia Inflata (Indian tobacco), Emetics, stimulants, .• , • , ’ purgatives; stimulate 1 -.P _ ’ • , , , with ammonia, alcohol or i , • .. ’ e ec ricl Bites.—First wash thoroughly, then paint with carbolic acid (I strength), or tincture of iodine. Tie a handkerchief tightly above wound, until the doctor comes. Give alcohol freely in bites of snake, scorpion, tarantula, etc. Stings.—Extract “stinger,” if left behind. Apply mud, or a paste made of baking soda, or wash with ammonia. Poisoned Wounds, Dissecting Wounds, Infectious Diseases. Apply carbolic acid (i strength), or, paint with tincture of iodine. Give stimulants internally. Poisonous Gases.—See special gases in text. Treatment: Fresh air, rest, and mild stimulation. APPENDIX. We introduce here the following analyses of the various fluids of the body. Subjoined is the mean composition of the Blood, as given by Becquerel and Rodier:— Per cent. Water 78.16 Dry corpuscles 13.50 Albuminoids 7.00 Fibrin 0.25 Fats 0.17 Extractives 0.84 Earthy phosphates 0.C3 Iron 0.05 The ash of human blood is thus given by Jarisch in the 100 parts:— Per cent. Chlorine 30.74 Potash 26.55 Soda 24.11 Phosphoric acid 8.82 Sulphuric acid 7.11 Oxide of Iron 8.16 Lime and magnesia 1.83 Human Lymph, etc. (Schmidt.) Per cent. (Gubler and Que venue.) Per cent. (Hensen and biilinhardt.) Per cent. Water 96.39 93.48 98.52 Solids 3.6 6.52 1.48 Fibrin 0.6 Globulin substances and serum albumin. Fats, cholesterin, lecithin. Extractives. Sugar. 4.28 0.91 0.43 0.05 2.9 0.68 Salts .• 0.82 0.79 Sodic chloride 0.54 ' Soda 0.15 329 330 APPENDIX. Ash of Human Lymph (Dahnhardt, in 100 parts of Ash). Per cent. Sodic chloride....; 74.84 Soda 10.35 Potash 3.22 Lime 0.93 Magnesia ,.. 0.26 Phosphoric acid 1.09 Carbonic acid 8.21 Sulphuric acid 1.27 Ferric chloride 0.06 Human Chyle (0. Rees). Per cent. Water 90.48 Solids 9.52 Fibrin , a trace Albumin 7.08 Fats, lecithin, cholesterin, etc 0.92 Extractives 1.0 Salts 0.44 In the ether extract of chyle obtained from a human fistula, the following bodies were present in the 100 parts:— Per cent. Per cent. Cholesterin 11.3 to 14.1 Lecithin 7.5 “ 8.8 Olein 38.1 \ „ » . Palmitin and Stearin 43.0 j Mixed Saliva—Human. (Jacuboivitsch.) Per cent. • (Hammerbacher.) Per cent. Water 99.51 92.42 ' Solids 0.48 0.58 Soluble organic bodies (ptyalin, etc.) 0.13 0.14 Epithelium 0.16 0.22 Inorganic salts 0.182 0.22 Potassic sulphocyanate 0.006 0.004 Potassic and sodic chlorides 0.084 Analysis of Gastric Juice (Human) mixed with some saliya. (After C. Schmidt, etc.) Per cent. Water. 99.44 Solids. 0.56 Organic substances (pepsin and peptones).. 0.32 Free hydrochloric acid : 0.25 Sodic chloride 0.14 Potassic chloride 0.05 Calcic chloride 0.006 Phosphates of lime, magnesia, and iron 0.015 APPENDIX. 331 Analysis of Pancreatic Juice—Dog. (C. Schmidt.) From a freshly opened pancreatic duct. Per cent. Water 90.07 Solids 9.93 Organic substances as albumin, alkali albumin 9.04 Inorganic salts 0.89 Soda combined with albumin, and traces of lime and magnesia similarly combined 0.09 Sodium chloride 0.73 Potassium chloride 0.02 Phosphates of lime, magnesia, and soda 0.05 In post-mortem Bile, Hoppe Seyler obtained :— Per cent. Glycocholate of soda 3.03 Taurocholate of soda 0.87 “ “ “ (containing sulphurl 0.05 Soaps 1-39 Mucin.... 1.29 Lecithin 0.53 Cholesterin 0.35 Other organic substances insoluble in alcohol 0.14 Iron, probably as phosphate 0.006 In 100 parts, dry solids of bile obtained from a fistula, having a specific gravity of 1010, and 2.24 to 2.28 per cent, of solids, Jackson obtained:— Per cent. Glycocholate of soda 44.8 Sodic chloride 24.5 Palmitate and stearate of soda 6.4 Phosphate of soda 5.9 Carbonate “ “ 4.2 Cholesterin 2.5 Phosphate of lime 1.6 Potassic chloride 1.2 Lecithin 0.2 Fats * 0.4 Residue insoluble in alcohol and ether 8.1 Analysis of Human Milk and Cow’s Milk (Konig) Woman's Milk. Mean. Minimum. Maximum. Water 87.09 83.69 90.90 Total solids... 12.91 9.10 16.31 Fat 3.90 1.71 7.60 Milk sugar.... 6.04 4.11 7.80 Casein 0.63 0.18 1.90 Albumin 1.31 0.39 2.35 Albuminoids. 1.94 0.57 4.25 Ash 0.49 0.14 ? Cow's Milk. Mean. Minimum. Maximum. 87.41 80.32 91.50 11.59 8.50 19.68 3.66 1.15 7.09 4.92 3.20 5.67 3.01 1.17 7.40 0.75 0.21 5.04 3.76 1.38 12.44 0.70 0.50 0.78 332 APPENDIX. Analysis of Human Tears (Lerch). This fluid has the following simple composition :— Per cent. Water 98.00 Albumin, with traces of mucus 0.50 . Sodium chloride 1.40 Other salts, as alkaline and earthy phosphates 0.02 Sweat. The following is the composition of human sweat, according to Picard :— Per cent. Water 98.88 Solids. 1.12 Salts 0.57 Sodium chloride 0.22 to 0.33 Alkaline sulphates, phosphates, lactates, and potassium chloride 0.18 Fats, fatty acids and cholesterine 0.41 Epithelium 0.17 Urea 0.08 Normal Urine of the Twenty-Four Hours. (After Liebermann, as quoted by Charles). Constituents. Amt. in grains. Alterations Under Pathological Conditions. Water. 50 oz. Increased in diabetes, after absorption of effusions, in contracted kidney, etc. Diminished in acute fevers, cholera, drop- sies, etc. Sp. gravity. 1.020 Raised in diabetes mellitus, and occasion- ally in diabetes insipidus. Lowered in polyuria and certain cachectic conditions, depending on want of food etc. Total solids. 900 to 1100 Fluid ounces X by last two figs, of sp. gr. = total solids. Urea. 400 to 600 Increased in fevers to the crisis, in inter- mittent fever before the cold stage, in.dia- . betes, and after absorption of dropsical effusions. Diminished in dropsies, in chronic liver diseases, in Bright’s disease, after fevers, and in all conditions in which tissue change is hindered. Uric acid. 5 to 12 Increased in acute fevers, in diseases of the lungs interfering with respiration (as tubercular deposit, etc.), acute rheuma- tism, leukaemia. Diminished in diabetes, chronic gout, Addison's disease. APPENDIX. 333 Normal Urine of the Twenty-Four Hours. (Continued.) Constituents. Amt. in grains. Alterations Under Pathological Conditions. Kreatinin. 10 to 18 Increased in acute fevers, pneumonia, etc. Diminished in diabetes mellitus, debility, kidney disease, etc. Hippuric acid 6 to 15 Increased in fevers, diabetes mellitus, and chorea. Sulphuric acid 23 to 38 Having more or less the same source as urea, it will increase or diminish there- with. Phosphoric acid 48 to 54 Increased in fevers, in most acute nerve affections, and in tubercle of the lung. Diminished in many mental diseases, especially mania, and in chlorosis. Oxalic acid 0.3 Increased in catarrhal jaundice, and in oxalic acid diathesis. Carbolic acid. 0.015 Increased in certain diseases of the intes- tines, causing constipation (ileus, etc.), but has been observed to be increased also in certain cases of diarrhoea. Phosphate of lime. Phosphate of magnesium. 4 to 5 7 to 11 f 150 to 200 Increased in osteomalacia, rickets, scrofula, carcinoma, long continued sup- puration. Diminished in fevers. Increased in fevers at the outset, and with Chloride of sodium. Cl = 90 to the re-absorption of dropsical fluids. 120 Diminished during apyrexia, dropsies, Ha=60to 80 cholera, typhus, inflammations generally, and especially pneumonia. Free acid (calculated as o x a 1 i c acid). 30 to 60 Increased during the acme of acute febrile affections (on account, probably, of the diminished proportion of water present). Diminished in most diseases affecting the nutrition and leading to a deficiency therein. Indican. Total inor- ganic salts. Potassium. • Sodium. 0.07 to 0.05 200 to 380 38 to 48 140 to 180 Increased with diseases attended by con- stipation, and occasionally, also, in cases of diarrhoea. Calcium. Magnesium. 4 to 5 2 to 3 TABLE OF WEIGHTS AND MEASURES. ENGLISH WEIGHTS.- TROY WEIGHT. Pound. Ounces. Pennyweights. Grains. French Grammes. 1 12 240 5760 = 373.2419 1 20 480 — 31.1035 1 24 = 1.5552 APOTHECARIES’ WEIGHT. lb. 3 5 9 gr. Pound. Ounces. Drachms. Scruples. Grains. French Grammes. 1 12 96 288 5760 = 373.2419 1 8 24 480 = 31.1035 1 3 60 = 3.8879 1 20 = 1.2959 1 = .0648 AVOIRDUPOIS WEIGHT. Pound. Ounces. Drachms. Grains. • French Grammes 1 16 256 7000 = 453.5926 1 16 437.5 - 28 3495 1 27.343 = 1.7718 METRIC MEASURES. MEASURES OF LENGTH. 1 Millimetre = 0.001 of a metre. 1 Centimetre -= 0.010 of a metre. 1 Decimetre = 0.100 of a metre = about 4 inches. 1 Metre = 1.000 Metre - 30.37 Indies. 1 Decametre = 10.000 metres. 1 Hectometre = 100.000 metres. 1 Kilometre = 1000 000 metres = about § of a mile. 1 Myriametre — 10,000.000 metres = about 6J miles. MEASURES OF SURFACE. 1 Centiare = 1 Square metre = about 1J square yards. 1 Are = 100 Square metres. 1 Hectare = 10,000 Square metres = about 2% acres. 334 APPENDIX. 335 MEASURES OF VOLUME. 1 Cubic centimetre = 0.001 of a litre. 1 Litre (cubic decimetre) = 1000. cubic centimetres. 1 Cubic metre = 1000. cubic decimetres. 1 Cubic metre = 1000. litres, or 1 kilolitre. 1 Cubic metre = 1 stere. MEASURES OF WEIGHT. 1 Milligramme = 0.001 of a gramme = about jj1- of a grain. 1 Centigramme = 0.010 of a gramme. 1 Decigramme = 0.1(K>of a gramme. 1 Gramme* = 1.000 Gramme = about grains. 1 Decagramme = 10.000 grammes. 1 Hectogramme = 100.000 grammes. 1 Kilo(gramme) = 1000.000 grammes =* about 2} lbs. 1 Tonneau = 1000. Kilo’s = about 1 ton. 1 Are = 100 Sq. metres, • „ . 119.6 Sq. yards. 1 Centimetre = metre, • .3937 inches. 1 Cubic centimetre (of dist. water weighs 1 gramme) .061 cub. in. 1 Cubic decimetre (1 litre), = Imperial measure, 1.133 qts. 1 Cubic decimetre, = Wine measure, 0.8806 qts. 1 Cubic decimetre of water weighs 2.2046 lbs. Av. = 1000 grammes. 1 Cubic foot = 1728 cu. in. = 28315.31 c.c. 1 Cubic foot of water weighs at 62° F. (16.6° C.), 62.32 lbs. Av. 1 Cubic inch, 16.386 c.c. 1 Cubic inch of water weighs at 16.6° C. (62° F.), 252.46 grains. 1 Cubic inch of water weighs at 16.6° C. (62° F.), 16.372 grammes. 1 Cubic metre (1 stere) = 1000 litres = 35.30 cu. ft. 1 Drachm, troy, = 3.888 grammes = 5j. 1 Fluid ounce, imperial, = 28.4 c.c. = 1.7329 cu. in. 1 Fluid ounce, wine measure, (fSj) = 29.57 c.c. = 1.8047 cu. in. 1 Fluid ounce water, at 16.6° C. (62° F.), wine measure, weighs 456. grains. 1 Fluid ounce water, at 15.6° C. (60° F.), wine measure, weighs 29.57 grms. 1 Fluid drachm (f3jj = 3.697 c.c. 1 Foot, 12 in., 30.48 centimetres. 1 Gallon, imperial, = 277.27 cu. in. _ = 4.543 litres. 1 Gallon, wine, = 231 cu. in. = 3.785 litres. 1 Grain, troy, = 0.06479895 grams 1 Gramme (weight of 1 c.c. of water) at 4° C. (39.2° F.) = 15.4323487 grains. 1 Inch = 2.54 centimetres. 1 Kilogramme (1000 grms.) = 2.2046 lbs. Av. 1 Litre (see cubic decimetre), . 61.027 cu. in. 1 Metre (one-forty millionth of earth’s meridian), 39.3708 inches. 1 Minim = 0.0616 c.c. of water weighs 0.0616 grammes, = 0.95 gr. 1 Ounce, troy, = 480 grs. = 31.1 grammes. 1 Ounce, Avoirdupois, = 437.5 grs. = ' 28.35 grammes. 1 Pint, imperial, = 567.93 cu. in., wine measure, = 473.15 cu. in. 1 Pound, troy, = 5760 grs. = 373.24 grammes. 1 Pound, Avoirdupois, = 7000 grs. = 453.59 grammes. 1 Ton, Avoirdupois, = 2000 tbs. 907.2 kilo’s- 1 Tonneau, 1,000,000 grammes. 1000 kilo’s. ALPHABETICAL TABLE OF EQUIVALENT MEASURES. * Sometimes spelled gram in English and American books. 336 APPENDIX. Table of Specific Gravities Named in the U. S. Pharmacopeia, 1880. (Compiled by Prof. P. W. Bedford.) Acid Acetic 1.048 “ “ dil 1.0083 “ “ Glacial 1.056-1.058 “ Hydrobromic dil 1.077 “ Hydrochloric 1.160 “ • “ dil 1.049 “ Lactic 1.212 “ Nitric 1.420 “ “ dil 1.059 “ Oleic 800-.810 “ Phosphoric 1.347 “ “ dil 1.057 “ Sulphuric 1.840 “ “ Aromat 955 “ “ dil 1.067 “ Sulphurous 1.022-1.023 Hither - 750 “ Acetic 889-. 897 “ Fortior 725 Alcohol 820 “ dil 928 Amyl Nitras 872-.874 Aq. Ammon 959 “ “ Fort 900 Bals. Peru 1.135-1.150 Benzinum .670-.675 Bromum 2.990 Camphora 990-.995 Carbonei Bisulphidum 1.272 Cera Alba 0.965-0.975 Cera Flava 955-.967 Cetaceum 0.945 Chloroform Puris 1.485-1.490 “ Venale. 1.470 Copaiba 940-.993 Creasote 1.035-1.085 Fel Bovis 1.018-1.028 Glycerinum 1.250 Hydrargyrum 13.5 Iodoformum 2.00 Liq. Ammon. Acet 1.022 “ Calcis .’ 1.0015 “ Ferri Acetatis 1.160 “ “ Chloridi 1.405 “ “ Citratis 1.260 “ “ Nitratis 1.050 “ “ Subsulph 1.555 “ “ Tersulph 1.320 Liq. Hydrarg. Nit 2.100 “ Plumbi Subacetatis 1.228 “ Potassae , 1.036 “ Potassii Citratis 1.059 “ Sodas. 1.059 “ “ Chloratas 1.044 “ Sodii Silicatis 1.300-1.400 “ Zinci Chlor 1.555 Mel 1.101-1.105 Oleum Adipis 0.900-0.920 “ iEtherum 0.910 U \ A * /1.060-1.070 Amygd.Amar.jj 043_104J) “ “ Express... .914-.920 “ Anisi 976-. 990 “ Aurantii Cort 890 “ “ Flor 850-.890 “ Bergamii 860-.890 “ Cajuputi 920 “ Cari .920 “ Caryoph 1.050 “ Chenapodii 920 “ Cinnamomi {Ceylon).. 1.040 “ “ (Chinese) 1.060 “ Copaiba 890 “ Coriandri .'. 870 “ Cubebae 920 “ Erigerontis 850 “ Eucalypti 900 “ Fceniculi .' 960 “ Gaultheriae 1.180 “ Gossypii Sem 920-.930 “ Hedeomae 940 “ Juniperi 870 “ Lavendulae 890 “ “ Flor 890 “ Limonis 850 “ Lini 936 “ Menth. Pip 900 “ “ Yirid 900 “ Morrhuae 920-.925 “ Myrciae 1.040 “ Myristicae 930 “ Olivae 915-.918 •“ PicisLiquida 970 “ Pimentae 1.040 “ Ricini 950-.970 “ Rosas 860 APPENDIX. 337 Table of Specific Gravities. (Continued.) Oleum Rosmarini 900 “ Rutse 880 “ Sabin ae : 910 “ Santali 945 “ Sassafras 1.090 “ Sesami 914-.923 “ Sinapis Volatile.. 1.017-1.021 “ Succini 920 “ Terebinthinias 855-. 870 “ Thymi 880 “ Tiglii 940-.955 “ Valerianae 950 Petrolatum 835-. 860 Phosphorus (at 50° F.) 1.83 Resina 1.070-1.080 Sp. HUtheris Nitrosi 823-.82S “ Ammonias 810 “ Ammoniae Aromat 885 Frumenti 930-.917 “ Vini Gallici 941-.925 Syrupus 1.310 Syr. Acidi Hydriodici 1.300 Thymol 1.028 Tinct. Ferri Acetas 0.950 “ “ Chloridi 0.980 Yinum Album 990-1.010 “ Rubrum 989-1.010 Zincum 6.9 See List of Tests by Hans Wilder, Appendix. Table showing the Solubility of some Chemicals in Glycerine. One Hundred parts of Glycerine Dissolve the Annexed Quanti- ties of the Salts.—(Klever). Parts Arsenious oxide 20.00 Arsenic oxide 20.00 Acid, benzoic 10.00 “ oxalic 15.00 11 tannic 50 00 Alum ;. 40.00 Ammonium carbonate 20.00 “ chloride 20.00 Antimony and potassium tar- trate 5.50 Atropia 3.00 “ sulphate 33.00 Barium chloride 10.00 Brucia 2.25 Cinchonine 0.50 “ sulphate 6.70 Copper acetate 10.00 “ sulphate : 30.00 Iron and potassium tartrate... 8.00 lactate 16.00 “ sulphate 25.00 Mercuric chloride 7.50 Mercurous chloride 27.00 Iodine 1.90 Morphine 0.45 Parts Morphine acetate 20.00 “ chlorhydrate 20.00 Phosphorus 0.20 Plumbic Acetate 20.00 Potassium arseniate 50.00 “ chlorate 3.50 “ bromide 25.00 “ cyanide 32.00 “ iodide 40.00 Quinine 0.50 “ tannate 0.25 Sodium arseniate 50.00 “ bicarbonate 8.00 “ borate 60.00 “ carbonate 98.00 “ chlorate 20.00 Sulphur 0.10 Strychnine 0.25 “ nitrate 4.00 “ sulphate 22.50 Urea 50.00 Veratrine 1.00 Zinc chloride 50.00 “ iodide 40.00 “ sulphate 35.00 338 APPENDIX, Solubility of the most important Chemicals used in Medicine, in Water and Alcohol. (Columns 1 and 3 taken from U. S. Pharmacopoeia), Explanation of Signs. s. = soluble ; ins. = insoluble ; sp. = sparingly soluble ; v. s. = very soluble ; aim. = almost; dec. = decomposed. Name or Chemical. Water. Alcohol. At 15° C. (59° F.) At 15° C. grs. pr fSj. At 15° C. (59° F.) At 15° C. grs. pr fSj. One part is soluble in :— Acid Arsenious Parts. 30-80 15.2-5.7 Parts. sp. “ Benzoic 500 0.9 3 124.6 “ Boracic 25 18.2 15 24.9 “ Carbolic 20 22.8 v. s. “ Chromic v. s. dec. “ Citric 0.75 608 1 374 “ Gallic 100 4.5 4.5 83.1 ‘‘ Salicylic 450 1.01 2.5 149.6 “ Tannic 6 76 0.6 623 “ Tartaric 0.7 651 2.5 149.6 Alum 10.5 43.4 ins. “ Dry, (Exsiccatum) 20 22.8 ins. Aluminium Hydrate ins. ins. “ Sulphate 1.2 380 aim. ins. Ammonium Benzoate 5 91.1 28 13.3 “ Bromide 1.5 300.4 150 2 4 “ Carbonate 4 114 dec. “ Chloride 3 152 1.37 273 “ Iodide 1 456 9 41.5 “ Nitrate 0.5 910 20 18 7 “ Phosphate 4 114 0.5 748 Sulphate 1.3 350.7 sp. Valerianate v. s. V. s. Antimony and Potass. Tartrate “ Oxide 17 26.8 ins. ilm. ins. ins. “ Sulphide ins. ins. Apomorphine Hydrochloride 6.8 67 50 7.4 Silver Cyanide ins. ins. “ Iodide ins. ins. “ Nitrate 0.8 570 26 14.3 “ Nitrat.e (fused) ' 0.6 760 25 14.9 . “ Oxide v. sp. ins. Arsenic Iodide 3.5 130.2 10 37.4 Atropine “ Sulphate 600 0.4 0.7 1152 v. s. 6.5 57.5 APPENDIX. 339 Solubility of the most important Chemicals used in Medicine, in Water and Alcohol. (Continued.) Name of Chemical. Water. Alcohol. At 15° C. (59° F.) At 15® C. grs.pr.fSj. At 15° C. (59° F.) At 15° 0. grs.pr.fSj. Bismuth Citrate ins. ins. “ and Ammon. Citrate v. s. sp. “ Subcarbooate ins. ins. “ Subnitrate ins. ins. Bromine 38 13.8 dec. Caffeine 75 6.08 35 10.6 Calcium Bromide 0.7 651 1 374 “ Carbonate ins. ins. “ Chloride 1.5 300.4 8 46.7 “ Hypophosphite 6.8 67 ins. Phosphate (precipitated)... ins. ins. Lime (Calx) 750 6.6 ins. Camphor, Monobromated Cerium Oxalate aim. ins. v. s. ins. ins. Chloral v s. V. s. Cinchonidine Sulphate 100 4.5 71 5.2 Cinchonine aim. ins. 110 3.4 “ Sulphate 70 6.5 6 62.3 Codeine 80 5.7 V. s. ... Chalk (Creta) ins. ins. Copper Acetate ‘ Sulphate 15 30.2 135 2.7 2.6 173.1 ins. Elaterium ins. 125 2.9 Ferric Chloride v. s. v. s. “ Citrate s. ... ins. “ and Ammon. Citrate V. s. ins. “ “ “ Sulphate 3 152 ics. “ “ “ Tartrate V. s. ins. “ “ Potass. Tartrate V. s. ins. “ “ Quinine Citrate s. ins. “ “ Strychnine Citrate V. s. ins. “ Hypophosphite sp. ins. “ Lactate 40 11.4 aim. ins. “ Oxalate sp. ins. ‘ ‘ Hydrate ins. ins. “ Phosphate V. s. ins. “ Pyrophosphate V. s. ins. “ Sulphate 1.8 253.3 ins. “ Valerianate ins. v. s. Hyoscyamine Sulphate v. s. V. s. Iodoform ins. 80 4.6 340 APPENDIX, Solubility of the most important Chemicals used in Medicine, in Water and Alcohol. (Continued.) Name of Chemical. Wateb. Alcohol. At 15° C. (59° F.) At 15° C. grs. pr fSj. At 15° C. (59° F.) At 15° C. grs. pr fSj Iodine sp. 11 34 Lithium Benzoate 4 114 12 31.1 “ Bromide V. s. v. s. “ Carbonate 130 3.5 ins. “ -Citrate 5.5 83.7 sp. “ Salicylate v. s. V. s.. Magnesium Oxide aim. ins. ins. “ Carbonate aim. ins. ins. “ Sulphate • 0.8 570 ins. “ Sulphite 20 22.8 ins. Manganesium Dioxide (Black Oxide). ins. ins. Manganesium Sulphate 0.7 651 ins. Mercuric Chloride 16 285 3 124 Mercurous Chloride ins. ins. Mercuric Cyanide 12.8 3.5 15 24.9 “ Iodide (Bed) aim. ins. 130 2.8 Mercurous Iodide (Green) aim. ins. ins. Mefcuric Oxide ins. ins. “ Subsulphate ins. ins. “ Sulphide (Bed) ins. ins. Morphine “ Acetate : v. sp. 100 3.7 12 38 68 5.5 “ Hydrochloride .' 24 19 63 5.9 “ Sulphate 24 19 702 0.5 Phosphorus ins. v. sp. Physostigmine Salicylate 130 3.5 12 31.i Picrotoxine. 150 3.4 10 37.4 Pilocarpine Hydrochloride v. s. v. s. Piperine aim. ins. 30 12.4 Plumbic Acetate 1.8 253.3 8 46.7 “ Carbonate ins. ins. “ Iodide 2000 6.2 v. sp. aim. ins. “ Nitrate 2 228 “ Oxide ins. ins. Potassium Hydrate 0,5 910 2 187 “ Acetate 0.4 112.5 2.5 149.6 “ Bicarbonate 3.2 142.5 aim. ins. “ Bichromate 10 45.6 ins. ‘ ‘ Bitartrate 210 2.1 v. sp. “ Bromide 1.6 285 200 1.8 APPENDIX. 341 Solubility of the most important Chemicals used in Medicine, in Water and Alcohol. (Continued.) Name of Chemical. Water. Alcohol. At 15° C. (59° F.) At 15° C. grs. pr fSj. At 15° C. (59° F.) At 15° C. grs. pr fgj. Potassium Carbonate 1 456 ins. “ Chlorate 16.5 27.6 v. sp. “ Citrate 0.6 760 v. sp. “ Cyanide 2 . 228 sp. “ and Sodium Tartrate 2.5 182.4 aim. ins. “ Ferrocyanide 4 114 ins. “ Hvpophosphite 0.6 760 7.3 51 “ Iodide 0.8 570 18 20.7 Nitrate 4 114 aim. ins. Permanganate 20 22.8 dec. Sulphate 9 50.6 ins. Sulphite 4 114 sp. Tartrate 0.7 651 aim. ins. Quinidine Sulphate 100 4.5 8 46.7 Quinine 1600 0.2 6 62.3 “ Bisulphate 10 45.6 32 11.6 “ Hydrobromate 16 28.5 3 124.6 “ Hydrochloride 34 13.4 3 124.6 “ Sulphate 740 0.6 65 5.7 “ Valerianate 100 4.5 5 74.8 Sugar, Cane 0.5 910 175 2.1 “ Milk 7 65.1 ins. Salicin 28 16.2 30 12.4 Santonin aim. ins. 40 9.3 Sodium Hydrate 1.7 268.2 V. s. “ Acetate 3 152 30 12.4 “ Arseniate 4 - 114 v. sp. “ Benzoate 1.8 253.3 45 8.3 “ Bicarbonate 12 38 ins. “ Bisulphite 4 114 72 5.2 “ Borate (Borax) 16 28.5 ins. “ Bromide 1.2 380 13 28.7 “ Carbonate 1.6 285 ins. “ Chlorate 1.1 44.5 40 9.3 “ Chloride 2.8 162.8 aim. ins. “ Hypophosphite 1 456 30 12.4 “ Hyposulphite 1.5 300.4 ins. “ Iodide 0.6 .760 1.8 207 “ Nitrate 1.3 350.7 sp. “ Phosphate 6 76 ins. “ Pyrophosphate 12 38 ins. ... 342 APPENDIX. Solubility of the most important Chemicals used in Medicine, in Water and Alcohol. (Continued.) Name of Chemical. Water. Alcohol. At 15° C. (59° F.) At 15° C. grs. pr fSj. At 15° C. (59° F.) At 15° C. grs. pr fSj. Sodium Salicylate 1.5 300.4 6 62.3 “ Santoninate 3 152 12 31.1 “ Sulphate 2.8 162.8 ins. “ Sulphite 4 114 sp. “ Sulphocarbolate 5 91.2 132 2.8 Strychnine 6700 0.06 110 3.4 “ Sulphate 10 45.6 60 6.2 Sulphur ins. ins. Thymol 1200 6.3 1 374 Veratrine v. sp. 3 124.6 Zinc Acetate O 152 30 12.4 “ Bromide V. s. v. s. “ Carbonate ins. ins. “ Chloride v. s. v. s. “ Iodide v. s. V. s. “ Oxide ins. ins. “ Phosphide ins. ins. “ Sulphate 0.6 760 ins. “ Valerianate 100 4.5 40 9.3 APPENDIX. 343 INCOMPATIBLES. Substances are said to be chemically incompatible when, on being mixed together, they react upon each other so as to cause an entire change in the properties of the substances so mixed. They may cause the evolution of a gas, an explosive mixture or compound, a poisonous or very active substance formed from comparatively inert ones, or, a pre- cipitation of one or the other of the ingredients in the new compounds formed.- Sometimes two or more substances are brought together with the intent of producing a new substance different from either; as, 2KI + HgCl2 = Hgl2 -f- 2KC1. This can hardly be regarded as an incompatible mixture. Of physiological or therapeutical incompatibility we shall have nothing to say here. The student will find the following rules of value to him in the beginning. 1. A free acid is incompatible with the alkaloids and the metallic hydrates and carbonates. The three mineral acids displace the organic acids from their salts. The converse of these statements is also true; i- e., metallic hydrates and carbonates are incompatible with the acids. 2. If two substances, when mixed, can form an insoluble third body, or can react so as to generate a gas, they are incompatible. A knowledge of the solubility of the ordinary salts is, therefore, of great importance to the physician. For example, lead or barium cannot exist in a solution with a sulphate; silver, lead, or mercurous mercury cannot exist in a solution with a chloride. Substances are, therefore, incompatible with their tests and antidotes. 3. The alkaline hydrates and carbonates are incompatible with the salts of the alkaloids and most salts of the heavy metals. 4. Iodides and bromides precipitate most of the heavy metals, and are therefore incompatible with them. 5. The vegetable astringents and bitters owe these properties largely to their gallic and tannic acids. Tannic acid and most vegetable astringents precipitate the heavy metals from their salts, and are therefore incom- patible with them. 6. Powerful oxidizing agents (strong nitric acid, potassium permanga- nate, hydrogen peroxide, chlorine, the hypochlorites, potassium chlorate, etc.), should not be mixed with easily oxidizable organic substances for fear of forming explosive compounds. 7. The two principal solvents of the IT. S. P. are alcohol and water. Each of these has its own class of easily soluble bodies. These bodies are often precipitated from their solutions in either of these solvents by the addition of the other. Thus the tinctures of iodine, camphor, essential oils, the gums and gum-resins, aloes, etc., are precipitated or rendered unsightly by the addition of water or watery solutions of drugs or chemi- cals. 8. There are some solutions which should always be prescribed alone, °r in a plain watery solution, as they readily decompose. Among these uiay be mentioned the compound syrup of the Hypophosphites, Fowler’s, Donovan’s, and Lugol’s solutions. These few rules will serve to call the student’s attention to the subject, and to the general range of incompatibles. GLOSSARY OF UNUSUAL CHEMICAL TERMS. [ The figures in parentheses refer to the pages of this book where a fuller explanation may be found.] J\ CTINISM. The chemical effects of light. Verdigris. Impure subacetate of copper. iEthiops. Black sulphide of mercury. Hg2S. Aerometer. Hydrometer. (13.) Alabaster. A light-colored, compact gypsum. CaS04. (197.) Alchemy. The Arabic name for chemistry, which formerly arose out of the search for the philosopher’s stone and elixir of life. Alembic. A form of still or retort, used in sublimation. Alkarsin. Oxide of cakodyl, or cacodylic acid. As(CH3)202H. Alloy. A mixture or compound formed by fusing two or more metals together. Amidon. Starch. (271.) Amorphous. Without a definite crystalline form. Anhydride. An oxide which can combine with the elements of water to produce an acid. Hence, an acid deprived of one or more molecules of water. Anode. The -f pole of a voltaic circuit. Apple Oil. Valerianate of amyl. Aqua Fontana. Aqua, U. S. P. Aqua Fortis. Crude nitric acid. (141.) Aqua Phagedsenica. Yellow wash. Mercuric hydrate. Aqua Regia. Nitro-muriatic acid. (142.) Aqua Vitae. Brandy. Argols. Crude cream of Tartar. (193.) Auripigmentum. Orpiment. Arsenious sulphide. Arrack. A spirituous drink made from the juice of the cocoanut tree. Austral. The south pole of a magnet. Azote. (Fr.) Nitrogen. Azotic Acid. Nitric acid. (141.) 345 346 GLOSSAKY J3ALDWIN’S Phosphorus. Fused calcium nitrate,possibly luminous calcium sulphide. Balsam of Sulphur. A solution of S. in 01. olivse. Barilla. The ashes of sea plants, and of Salsola Soda. Basyl. A term applied to an electro-positive radical. Battery. An apparatus for the production of electricity by chemical action. (40.) Baume. The name of the inventor of a hydrometer bearing this name. Bell Metal. An alloy of 6 parts copper and 2 parts tin. Bestuchuf’s Tincture. An ethereal solution of Fe2Cl6. Bibron’s Antidote. A solution of HgCl2,KI, bromine, alco- hol and water. Bittern. The mother liquor remaining after extracting NaCl from sea water, by evaporation and crystallization. Black Ash. Impure Na2C03, mixed with carbon. Black Flux. Made by igniting cream of tartar with one-half its weight of nitre; KISK)3. It contains carbon and K2C03. Black Drop. Acetum opii. Vinegar of opium. Black Lead. Plumbago, a native variety of carbon, used for making lead pencils, crucibles, and stove polish. (166.) Black Salts. The ley of wood-ashes evaporated nearly to dry- ness. Black Wash. Contains suboxide of mercury, Hg20. (231.) Bleaching Powder. Chloride of lime. A mixture of chloride and hypochlorite of calcium. (199.) Blende. Fative sulphide of zinc. ZnS. (205.) Blue Mass. Pilulae Hydrargyri. Blue Ointment. Unguentum Hydrargyri. Blue Vitriol, or Bluestone. Sulphate of copper. (227.) Bole. An argillaceous earth. Bone Ash. Bone black, or charred bones. (200.) Borax. Biborate of sodium. Tetraborate of sodium, Na2B407. (185.) Boreal. The north pole of a magnetic needle. Brass. An alloy of copper and zinc. Brimstone. Roll sulphur. (120.) British Barilla. Black Ash. British Gum. Dextrin. (272.) Bronze. An alloy of copper and tin. (239.) Brunswick Green. Oxychloride of copper. Bunsen Burner. A gas burner used for production of heat. It mixes the gas and air before burning them. GLOSSARY. 347 Burnett’s Disinfecting Fluid. Solution of ZnCl2. (133.) Butter of Zinc, Antimony, and Bismuth. Their chlorides. Impure, native carbonate of zinc. (205.) Calcareous Spar. Calcite. CaC03. (200.) Calcedony. A native form of Si02. Calcining. Igniting a substance in the air, so as to burn off any oxidizable material, or expel volatile products. Calcined Mercury. Mercuric oxide. HgO. Calomel. Mercurous chloride. Mild chloride of mercury. Hg2Cl2. (230.) Caloric. Old term for heat. Calorie. The unit of heat used in determining the heat of combination of chemical compounds. (27.) Camphene. Oil of turpentine. Camphene burning fluid is a solution of turpentine in alcohol. Canton’s Phosphorus. Luminous CaS, or luminous paint. Caput Mortuum. The residue left after ignition of FeS04 or iron pyrites. Impure Fe203. (215.) Caramel. Burned sugar. (269.) Carbolic Acid. Phenic acid. Phenyl alcohol. (287.) Carburet. Carbide. Catalysis. The action of a body in promoting combination or decomposition by its presence, the body itself remaining un- changed. Cathode. The negative pole of a galvanic circuit. Chalk. An amorphous carbonate of lime. (200.) Chameleon Mineral. Permanganate of potassium. Choke Damp. Carbonic anhydride. C02. (171.) Chrome Green. A mixture of chrome yellow and Prussian blue; or sesquioxide of chromium. Cr203. (208.) Chrome Vermilion. Dichromate of lead. PbCr207. Chrome Yellow. Chromate of lead. PbCr04. (223.) Cinnabar. Native red sulphide of mercury. HgS. (229.) Citrine Ointment. Nitrate of mercury ointment. Clay. Impure silicate of alumina. Clay Ironstone. A variety of hematite iron ore. Fe203. Colcothar. Ferric oxide. Fe203. Rouge, crocus. Collodion. Solution of gun cotton in alcohol and ether. (273.) Colloids. Jelly-like or non-crystallizable bodies. (57.) Colophony. Common resin, or rosin. (252.) Condy’s Solution. Contains permanganate of potassium. K2Mn208. (133.) 348 GLOSSARY. Common Salt. Sodium chloride. NaCl. Copperas. Green vitriol. Crystallized ferrous sulphate. FeS04.7Aq. (214.) Corrosive Sublimate. Mercuric chloride. Bichloride of mercury. (326.) Cream of Tartar. Acid potassium tartrate. HKC4H406. (193.) Crocus of Antimony, or Crocus Metallorum. Oxysul- phide of antimony. (159.) Crocus Martis. Colcothar. Fe203. Crystals of Venus. Copper acetate. Cu(C2H302)2.H20. Crystalloids. Crystallizable bodies, as distinguished from col- loids. (58.) Cubic Nitre. Sodium nitrate. NaN03. Cupellation. The process of purifying silver or gold in a cupel or cup made of bone ash. When the alloy is strongly heated in air, the other metals oxidize and the cupel absorbs the oxide, leaving the silver or gold pure. TAECANTATION. The process of pouring off the clear liquid above a sediment. Decoction. An extract of an organic substance, made with boiling water. Displacement. Expelling a fluid from a vessel by another of different density. Decrepitation. The crackling of certain salts when suddenly heated. Deflagration. A rapid and scintillating combustion. It takes place in certain mixtures containing the nitrates or chlorates. Deliquescent. An adjective applied to those substances which attract moisture from the air and liquefy. (55, 59.) Destructive Distillation. Dry distillation, conducted with the object of destroying the substance and producing new ones. (25.) Detonation. Rapid chemical action, accompanied by flame and noise. An explosion. De Valangin’s Arsenical Solution. A solution of the chloride. AsC13. Liq. Arsen. Hydrochlor. Dew-point. The temperature at which the moisture of the air begins to deposit. Dialysis. The process of the diffusion of liquids and solutions through membranes. (57.) Dimorphous. Crystallizing in two distinct systems. (58.) GLOSSARY. 349 Donovan’s Solution. Contains the iodides of arsenic and mercury. Dolomite. Magnesium limestone. (203.) Dover’s Powder. Compound ipecac, powder; contains opium. (1 gr. in 10). Drummond Light. Calcium light. Dry Distillation. The process of subjecting solid or organic bodies to heat, in a closed retort. Ductile. Capable of being drawn into wire, or rolled out into sheets. Dutch Gold. A species of brass, usually sold in very thin leaves or sheets. Dutch Liquid. Ethene dichloride. C2H4C12. Dutch White. Impure white lead. EAU. de Javelle. A solution of chlorinated potassa, or potass, hypochlorite. KOC1. Educts. The proximate principles of which bodies are sup- posed to be formed. Effervescence. The rapid escape of gas from a liquid. Efflorescence. The escape of water of crystallization and the consequent crumbling down of the crystal. (59.) Electrode. The pole or wire forming a part of a voltaic cir- cuit. (45.) Electrolysis. Decomposition by means of a strong electric current. (51.) Element. A substance which has never been decomposed. Elixir of Vitriol. Aromatic sulphuric acid. Elutriation. The process of separating the finer and lighter particles of a powder from the coarser, by suspending them in W'ater and pouring off the lighter floating particles with the water. Emerald Green. Schweinfurth green, or aceto-arsenite of copper. See Paris green.- Emery. An impure corundum. A1203. (238.) Eosine. Tetrabromo-fluorescine. A beautiful, red, artificial coloring matter. Epsom Salt. MgS04.7Aq. (204.) E remacausis. The slow decay of organic substances in the air. Essence of Mirbane. Nitro-benzol. (293.) Essential Oils. Volatile oils. (277.) Eudiometer. A graduated glass tube, closed at one end, used for measuring gases. 350 GLOSSARY. pERMENTATION. (321.) Filter. A porous substance used to separate a solid and liquid by allowing the latter to pass through, while the former is retained. Fire Damp. Light carbureted hydrogen (Marsh gas), mixed with air. (247.) Fixed Air. Choke damp. C02. (171.) Flint. An impure variety of silica. Si02. Flowers of Antimony. Oxide of antimony. Flowers of Benzoin. Benzoic acid. (289.) Flowers of Sulphur. Sulphur sublimatum. U. S. P. (120.) Flowers of Zinc. Oxide of zinc. ZnO. (206.) Fluorescence. The property possessed by certain bodies, as quinine salts, of rendering visible the ultra-violet or chemical rays of the solar spectrum. Fluor Spar. Native calcium fluoride. CaF2. (111.) Flux. A material added to ores in smelting, to form an easily fusible slag. Foliated Earth of Tartar. KC2H302. Potassium acetate. Fool’s Gold. Iron pyrites. Fowler’s Solution. Solution of the arsenite of potassium. (152.) French Chalk. Silicate of magnesia. Soapstone; talc. Fructose. Fruit sugar. Fuchsine. Aniline red. Magenta. C20H19N3. Fuming Liquor of Libarius. Solution of stannic chloride. Fusel Oil. Amylic alcohol. (264.) Fusible Calculus. One composed of a mixture of phosphate of lime, and ammonio-magnesium phosphate. Fusible Metal. Bismuth 2 parts, lead 1 part, and tin 1 part. Melts at about 200°F. PALENA. Native lead sulphide. (219.) Galvano-Cautery. A surgical knife heated by a gal- vanic current. German Silver. An alloy of copper, nickel and zinc. Glass. An artificial silicate of calcium, sodium, iron, lead, etc. Glass of Antimony. Fused trisulphide of antimony. Sb2S3. Glass of Borax. Fused borax. Glauber’s Salt. Sodium sulphate. (182.) Glucose. Grape sugar. Now made on large scale, from corn starch. (267.) GLOSSARY. 351 Glucoside. (See p. 297.) Glyceroles and Glycerita. Simple glycerine solutions. Goniometer. An instrument for measuring the angles of crystals. Goulard’s Extract, and Cerate. Contain subacetate of lead. Graphine. Carbon deposited in gas retorts. Graphite. Plumbago. Black lead. (166.) Green Vitriol. Copperas. FeS04.7Aq. (214.) Guano. A deposit of excrement of sea fowl. Gypsum. Calcium sulphate. Plaster of Paris. (199.) U ALOGEN Elements. Haloid Salt. The elements of the chlorine group and their binary compounds. (111.) Harle’s Solution. Solution of arsenite of sodium. Haschisch. Indian hemp. Hartshorn. Ammonia. (134.) Hepar Sulphuris. Liver of sulphur. Potassium sulphide. Hive Syrup. Compound syrup of squills. Hoffmann’s Anodyne. Spirit. Aether. Co. Ether, 1 pint; alcohol, 1 pint; ethereal oil, f3vj. Homberg’s Pyrophyrus. Is made by igniting potassium, alum and charcoal. H omologues. (245.) Homologous Series. (245.) Huxham’s Tincture. Compound tincture of cinchona. Hydracid. A binary acid. Contains no oxygen. Hydrate. A compound containing hydroxyl, HO, combined to a positive radical. (77.) Hydrochloride. A compound of HC1, formed by union of the whole molecule by synthesis; as compounds with the alkaloids. Hygrometer. An instrument for the determination of the relative amount of moisture in the air. JCE Vinegar. Glacial acetic acid. (279.) Incandescence. The glow of a highly heated body. Incineration. The reduction of a substance to ashes by burning. Incompatible. Incapable of being mixed without chemical change. (343.) Infusion. An extract of an organic substance, made by pour- ing hot water upon it and allowing it to stand for some hours. 352 GLOSSARY. Inosite. Muscle sugar. (271.) Ion. A body going to the positive (anode) or negative (cathode) pole of a galvanic battery during electrolysis. Iron Pyrites. Native sulphide of iron. Fools’ gold. Isinglass. A variety of gelatin, or fish glue. Sometimes erroneously applied to mica. Ivory Black. Animal charcoal, made by distilling ivory scraps; is now generally applied to bone black. JAMES’ Powder. Antimonial powder. Japan Black. A varnish composed of asphaltum, turpen- tine, linseed oil and umber. Jesuits’ Powder. Powdered cinchona bark. TU AO LIN. A pure white clay. Kelp. A shes of sea weeds; used as a source of iodine and carbonate of sodium. Kermes’ Mineral. Sb2S3. (160.) King’s Yellow. Orpiment. As2S3. Kyan’s Disinfectant. Solution of HgCl2. TABARRAQUE’S Disinfecting Liquid. Solution of hypochlorite of sodium or chlorinated soda. (186.) Lac Sulphuris. Precipitated sulphur. (122.) Lactin—Lactose. Sugar of milk. (269.) Lacquer. A varnish used for brass, etc. Lady Webster Pill. Pill of aloes. Lake. An organic coloring matter precipitated with alumin- ium hydrate. Used as pigments. Lampblack. The soot of burning turpentine. (167.) Lapis Infernalis. Lunar caustic. AgN03. Laughing Gas. Nitrous oxide. N20. Dentists’ gas. (137.) Lead Water. Diluted Goulard’s Extract, containing sub- acetate of lead. (223.) Ledoyen’s Disinfecting Liquid. Solution of nitrate of lead. Levigation. The reduction of a substance to an impalpable powder, by rubbing on a slab, with sufficient water to form a paste, with a flat pestle called a muller. Lime. CaO. (197.) Limestone. A native carbonate of lime. (197.) Litharge. PbO. Semi-vitrified oxide of lead. (220.) Lithic Acid. Uric Acid. (291.) GLOSSARY. 353 Liver of Sulphur. Potass, sulphuret. K2S. (192.) Lixiviation. The separation of the soluble portions of a sub- stance by causing water to filter through it. (110.) Loadstone. The native magnetic oxide of iron, or magnetite. A magnet. (205.) • Lugol’s Solution. Compound solution of iodine. Iodine held in solution by KI. (118.) Lunar Caustic. Nitrate of silver. AgN03. (236.) Lute. An adhesive mixture for closing the joints of apparatus, to prevent the escape of vapors, etc. TVT ACERATION. The long continued soaking of a sub- stance in water at common temperatures. (110.) Macquer’s Salt. Potassium arseniate. Magendie’s Solution. Morph, sulphate, gr. xvj, water, fsj. Magistery of Bismuth. Subnitrate. Magma. A pasty mass. Magnesia Alba. Magnesium carbonate. (205.) Malleable. Capable of being worked under the hammer. Marble. Nearly pure native carbonate of lime. (197.) M arine Acid. Muriatic acid. HC1. (114.) Martial ./Ethops. Fe304. Magnetic oxide of iron. Massicot. Amorphous oxide of lead. PbO. Powdered lith- arge. (220.) Matrass. A glass vessel with a long neck, or a tube sealed at one end. Used for heating dry substances. Mercaptan. An alcohol in which O is replaced by sulphur. Metalloid. Non-metal. (89.) Menstruum. A solvent, or medium of chemical reaction. Metameric Bodies. The same as isomeric. (246.) Microcosmic Salt. NaNH4HP04. Milk of Sulphur. Precipitated sulphur. Milk of Lime. Whitewash. (198.) Mineral Water. Water charged with carbonic .acid ; also natural water holding medicinal substances in solution. (109.) Mineral Yellow. Oxychloride of lead. Minium. Bed oxide of lead. 2Pb0.Pb02. (221.) Molecule. (See page 63.) Monsel’s Salt. Subsulphate of iron. (216.) Mosaic Gold. Brass. Mordant. A substance used to fix colors on fabrics. Mountain Blue. Azurite. Native basic carbonate of copper. 354 GLOSSARY, Mountain Green. Malachite. A native basic carbonate of copper. (228.) Mulberry Calculus. Calcium oxalate. CaC204. Muriatic Acid. Hydrochloric acid. (114.) Muriate. A chloride. 1\J APHTHA. A light hydrocarbon obtained from petroleum, and boiling at about 80° to 105°C. (248.) Natron. Native carbonate of sodium. (183.) Neutral. Without action on test paper. Neither acid nor alkaline. Neutral Mixture. Solution of citrate of potassium. Nitre. Saltpetre. KN03. (190.) Normal Salt. Neither acid nor basic. CVBSIDIAN. Volcanic glass. w Ochre. A native mixture of clay and ferric oxide, used as a paint. Oil of Vitriol. H2S04. Sulphuric acid. (125.) Oil of Wine. Ethyl sulphate. (C2H5)2S04. Oreide. A species of brass resembling gold, and used for jewelry. Orpiment. Arsenious sulphide. As2S3. (151.) Ortho-acid. An acid in which each bond of the kernel is united to hydroxyl. (OH.) Osmosis. The diffusion of liquids through porous septa. See Dialysis. (57.) Ox-acid. A ternary acid containing oxygen. TDACKFONG. A variety of German silver. Particle. A minute portion of matter. Paris Green. Impure Schweinfurth green. Aceto-arsenite of copper. (152.) Pearl Ash. Impure carbonate of potassium. (191.) Pearl Powder. Subnitrate, or oxychloride of bismuth. (BiO NO-, or BiOCl.) Pearl White. BiONO,, or BiOCl. Pearson’s Salt. Arseni ate of sodium. Na.-,As04. Pewter. An alloy of variable composition. Usually composed ot tin, lead, copper and antimony, or zinc. Pinchbeck Gold. A species of brass. Plaster of Paris. Calcium sulphate. Calcined gypsum. (199.) GLOSSARY. 355 Platinum Black and Sponge. Finely divided platinum. (240.) Plumbago. Native carbon. Graphite. (166.) Potash. Impure carbonate of potassium. (191.) Potassa. Oxide or hydrate of potassium. Powder of Algaroth. Oxychloride of antimony. (159.) Precipitate. An insoluble substance, formed on bringing two or more substances together in solution. Precipitatum Per Se. Mercuric oxide. HgO. Made by heating mercury to near its boiling point until it oxidizes. Preston Salts. Carbonate of ammonia, flavored with some essential oil. Prussic Acid. Hydrocyanic Acid. (176.) Prussian Blue. Ferric ferrocyanide. (179.) Pseudomorph. A mineral crystallized in the form that be- longs to another mineral. Puce-oxide of Lead. Lead peroxide, or brown oxide. Purgative Mineral Water. Liq. magnes. citrat. • Purple of Cassius. A pigment produced by treating chloride of gold with a solution of stannous chloride. (238.) Putty. Composed of whiting and linseed oil. Putty Powder. Stannic oxide. Pyrites. Native sulphide of iron. Pyroxilic Spirit. Wood alcohol. Methyl alcohol. (259.) Pyroxylin. Gun cotton. Trinitro-cellulose. (273.) QUANTIVALENCE. Quantity of combining power; applied to atoms. (71.) Quartz. Si02. (165.) Quevenne’s Iron. Ferrum redactum. (213.) Quicklime. Caustic lime. CaO. (197.) Quicksilver. Mercury. (229.) An atom, or group of atoms, forming the basis of a series of compounds. (74.) Radical Vinegar. Glacial acetic acid. Realgar. Red sulphide of arsenic. (151.) Red Precipitate. Red oxide of mercury. HgO. Red Prussiate of Potash. Ferricyanide of potassium. (179.) Red Tartar. Argol. (193.) Regulus of Antimony. Metallic antimony. Rochelle Salt. Tartrate of potassium and sodium. (193.) 356 GLOSSARY Roche and Roman Alums. Are varieties of potassium alum. Rock Crystal. Quartz. Si02. (165.) Roman Vitriol. Sulphate of copper. CuS04. Rouge. Ferric oxide in fine powder. Fe203. Ruby. Native A1203, of a beautiful red color. (238.) Rust. Ferric oxide; generally containing some ferric hydrate. (213.) C ACCHARUM Saturni. Acetate of lead. (223.) Safety Lamp. A lamp inclosed in wire gauze, to prevent explosions in explosive gases in mines, cellars, etc. Sal /Eratus. Potassium bicarbonate. (191.) Sal Alembroth. Double chloride of mercury and ammonium. Sal Ammoniac. Ammonium chloride. (135.) Sal Diureticus. Potassium acetate. Sal Enixum. Potassium bisulphate. Sal Mirabile. Sodium sulphate. Sal Perlatum. Sodium phosphate. Sal Prunelle. Fused nitre. KN03. Sal Volatile. Ammonium carbonate.. Salt of Lemon and Salt of Sorrell. Potassium binoxalate. (192.) Salt of Phosphorus. Microcosmic salt. Salt of Tartar. Pure potassium carbonate. (191.) Saltpetre. Potassium nitrate. (190.) Sapphire. A native form of A1203. Scheele’s Green. Arsenite of copper. (152.) Schlippe’s Salt. Sodium sulphantimoniate. Na3SbS4. Schweinfurth Green. Copper aceto-arsenite. (227.) Seidlitz Powder. A mixture of sodium bicarbonate and Rochelle salt in one paper and tartaric acid in another. Seignette’s Salt. Rochelle salt. KNaC4H406. (193.) Sizing. A gelatinous mixture put into paper or cloth, to fill up the pores. Slag. The fused impurities from smelting of ores. (217.) Smalt. Glass colored blue by oxide of cobalt and powdered. Smelting. The process of recovering the metals from their ores. Soda Ash. Crude sodium carbonate. (184.) Soda Saltpetre. Sodium nitrate. NaN03. (185.) Soluble Tartar. Neutral potassium tartrate. (192.) Speculum Metal. An alloy of copper and tin. GLOSSARY. 357 Speiss. Impure, fused nickel arsenide. Spelter. Commercial zinc. Spermaceti. A fat obtained from the sperm whale. Spirit of Hartshorn. Spirit of ammonia. Solution of am- monia in alcohol. Spirit of Mindererus. Solution of ammonium acetate. (196.) Spirit of Nitre. Spirit of nitrous ether. (141.) Spirit of Salt. Muriatic acid. (114.) Soapstone. Talc. (203.) Soda Water. Water artificially charged with C02 under pressure. Solder. An alloy of tin and lead. Soluble Glass. See Water Glass. (165.) Spirit of Wine. Alcohol. Steinbuhl Yellow. Barium chromate. BaCr04. Substitution. The displacement of an atom in a molecule by another atom of a different kind. (254.) Sugar of Lead. Lead actetate. (223.) Sulphuret. Sulphide. Sulphuric ./Ether. Ethylic ether. C4H10O. (275.) Sulphur Vinum. Impure sulphur. Horse brimstone. T'ALMI Gold. An alloy of copper and aluminium (90 to 1 10). Tartar Emetic. Antimony and potassium tartrate. (160.) Tasteless Purging Salt. Sodium phosphate. Thenard’s Blue. A compound of the oxides of aluminium and cobalt. Tincal. Native borax. Na2B407. (185.) Tincture. A solution in alcohol. When in ether, it is called an ethereal tincture. Tombac. A kind of brass. Tournesol. Litmus. Trituration. Rubbing in a mortar. Trona. Native sodium carbonate. (183.) Turnbull’s Blue. Ferrous ferricyanide. (179.) Turner’s Cerate. Calamine cerate. * Turner’s Yellow. Lead oxychloride. Turpeth Mineral. Yellow sulphate of mercury. (233.) Tutty. I mpure zinc oxide. Type Metal. An alloy of lead and antimony. (1 to 3.) 358 GLOSSARY. TIMBER. A native silicate of aluminium, with oxides of iron and manganese. Used as a brown paint. Ultramarine. Lapis lazuli. A compound of aluminium so- dium silicate with sodium sulphides. A beautiful blue pig- ment. It is now prepared artificially, as well as a green, red and violet variety. / "XIALENCE of Atoms. Quantity of combining power. Vallet’s Mass. FeC03 made into a pill mass. Varec. Kelp. Ash of sea weeds. Verd Antique. Precious serpentine. Verdigris. Impure copper subacetate. (228.) Verditer. Basic copper carbonate. Vermilion. Artificial mercuric sulphide. HgS. (233.) Vitriolic Acid. Sulphuric acid. (125.) YWATER Glass. Soluble glass. Sodium silicate. (166.) White Arsenic. Arsenious oxide. White Lead. A basic lead carbonate. (223.) White Precipitate. Ammoniated mercury. Mercur-amido- gen chloride. NH2HgCl. (232.) White Vitriol. Zinc sulphate. (206.) Whiting. Prepared chalk. CaCO:). White clay, often sold for whiting. Wood Naphtha and Wood Spirit. Methyl alcohol. (278.) Wood Vinegar. Pyroligneous acid. Impure acetic acid. (278.) VELLOW Prussiate of Potash. Potassium ferrocyan- 1 ide. (179.) Yellow Wash. Made by adding corrosive sublimate to lime water. It forms mercuric oxide. (233.) 7AFFRE. Impure cobalt oxide. Zinc White. Zinc oxide. Used as a paint. (223.) Zymosis. The peculiar action caused by a ferment. INDEX. Absorption spectra, 35 Acetamide, 292 Acetone, 258 Acetylenes, 247, 249 Acid, acetic, 278 “ acetic, glacial, 279 “ aconitic, 286 “ amido-caproic, 317 “ antimomc, 160 “ antimonious, 160 “ arsenic, 153 “ arsenious, 152 “ benzoic, 289 “ bismuthic, 162 “ boracic, 164 “ bromic, 117 “ butyric, 280 catt'eetannic, 303 “ capric, 305 “ caproic, 259, 305 “ caprylic, 259, 305 “ carbazotic, 288 “ carbolic, 287 “ carbonic, 174 “ catechu tannic, 303 “ chloric, 116 “ chlorous, 116 “ cholesteric, 313 “ cholic, 312 “ chromic, 209 “ citric, 286 “ cyanic, 178 ‘ ‘ dextrotartaric, 285 “ dichloracetic, 279 “ ethylsulphuric, 275 “ formic, 278 “ gallic, 303 hydrate, 131 “ sulphocyanate, 178 Ammonias, compound, 291 Ammonio-ferrous, sulphate 214 Ammonio magnesium phosphate, 204 Ampere’s law, 17, 66 Amygdalin, 301-319 Amyl acetate, 276 Amyl alcohol, 264 Amyl nitrate, 276 Amyloses, 271 Amylum, 271 Analysis, toxicological, 157 Anaesthetics, 326, 327 Anglesite, 222 Anhydride, boric, 164 molybdic, 241 nitric, 140 “ nitrous, 139 INDEX. Anhydride, silicic, 165 “ sulphuric, 125 “ sulphurous, 124 Anhydrite, 199 Anilin, 293, 297 “ colors, 294. Annatto, 316 Anthracene, 253 Antiarin, 301 Antimony, 158 Antimony and potass., tartrate of, 160,194 Antimony, butter of, 159 “ chloride, 159 “ crocus of, 159 “ glass of, 159 “ hydride, 158 oxide, 160 “ oxychloride, 159 “ protochloride, 159 “ pentachloride, 159 “ physiological action, 161. “ sulphate, 160 “ sulphide, 159 “ trioxide, 160 “ trichloride, 159 vermilion, 160 Antipyrine, 297 Antiseptics, 132 Apomorphine, 298 Appendix, 329 Aqua, 109 “ ammonise, 135, 194 “ “ fort., 135, 194 “ chlorina, 113 “ fortis, 147 “ regia, 142 Arabin, 274 Arabinose, 274 Arbutin, 301 Argentum, 235 Argol, 193, 285 Arsenic, 149 “ disulphide, 151 “ fluoride, 151 “ iodide, 151 “ oxides, 152 “ pentasulphide, 151 “ poisoning, 153 “ tribromide, 151 362 INDEX. Arsenic, trichloride, 151 “ trisulphide, 151 Arsine, 150 Asbestos, 203 Asepsis, 132 Asafoetida, 253 Atmosphere, 129 Atoms, definition of, 69 “ equivalent of, 71 Atomic weight, 69 Atropine, 297 Aurates, 238 Auric, chloride, 238 “ oxide, 238 Aurous oxide, 238 Avogadro’s law, 17, 66 Azurite, 227 Baking powders, 193 Balsam copaibse, 252 Balsam Peru, 253 Balsams, 252 Barium, 197, 202 “ carbonate, 202 “ chloride, 202 “ nitrate, 202 “ oxide, 202 “ physiological, effects of, 202 “ sulphate, 202 Baryta, 202 Barite, 202 Base, 77 Bases, organic, 294 Basicity of acids, 77 Batteries, care of, 42 “ polarity of, 42 “ storage, 43 Battery, Bunsen, 40 “ Callaud, 41 “ Grove, 40 “ Leclanch6, 41 Benzine, 248, 253 Benzoin, gum, 252 Benzol, 253 Berthelet’s laws, 84 Beryllium, 203 Bessemer steel, 213 Bile, 312 “ composition of, 331 Biliary coloring matters, 313 Biliary compounds, 312 Bilicyanin, 314 Bilifulvin, 313 Bilifuscin, 313 Bilihuinin, 313 Biliphaein, 313 Biliprasin, 313 Bilirubin, 313 Biliverdin, 313 Bismuth, 162 “ carbonate, 163 “ chloride, 162 “ citrate, 163 “ nitrate, 162 “ oxide, 162 “ subcarbonate, 163 “ subnitrate, 163 “ physiological action of, 163 Bites, 327 Bitumen, 248 Black wash, 231 Blast furnace, 212 Bleaching powders, 198 Blende, 205 Blood, composition of, 329 “ appearance in C02 poisoning, 171 Blue stone, 227 “ vitriol, 227 Body, definition, 10 Boiling point 24 Bone ash,200 “ black, 167 “ phosphate, 199 Borax, 164, 185 Boroglyceride, 165 Boron, 164 “ chloride, 164 “ fluoride, 164 “ nitrate, 164 Braunite, 210 Brazil wood, 316 Brimstone, 120 Brighton green, 228 British gum, 272 Bromal, 258 Bromine, 116 Bromoform, 261 Brucine, 297 Bunsen’s battery, 40 INDEX. 363 Burnett’s fluid, 133, 326 Butter, 305 “ of antimony, 159 Butterine, 305 Butylen, 249 Butyric acid, 280 “ fermentation, 322 CADMIUM, 203, 207. “ chloride, 207 “ compounds of, 207 “ hydrate, 207 “ iodide, 207 “ oxide, 207 “ sulphate, 207 “ sulphide, 207 Caesium, 194 Caffeine, 297 Calabar bean, 327 Calamine, 205 Calcium, 197 bromide, 198 “ carbonate, 200 “ chloride, 198 “ hydrate, 198 “ iodide, 198 “ hopochlorite, 198 “ light, 198 “ oxalate, 201 “ oxide, 197 “ salts, 198 sulphate, 199 sulphocarbolate, 288 physiological effects, 201 Calculus, fusible, 205 CaUaud’s battery, 41 Calomel, 230 Caloric, 27 Calorie, 27 Calx, 197 Camphor, 250 ‘ dibromide, 251 “ monobromated, 251 Camphors, 250 Cane sugar, 268 Caoutchouc, 250 Caramel. 269 Carat, 238 Carbohydrates, 267 Carbon,' 166 “ amorphous, 167 Carbon and hydrogen, 243 “ and oxygen, 170 “ and sulphur, 175 “ dioxide, 171 “ “ in air, 130 “ disulphide, 131, 175 “ gas retort, 168 “ monoxide, 170 “ monosulphide, 175 “ nuclei, 244 “ suboxide, 170 Carbonates, 174 Carmine, 316 Carnallite, 188 Carnin, 318 Casein, 309 Caseins, vegetable, 310 Caustic alkalies, 180 “ “ poisoning by, 186 “ potash, 188 “ soda, 181 “ lunar, 236 Cell, Bunsen’s, 40 “ galvanic, theory of, 38 ‘‘ Groves’, 40 “ Leclanch6, 41 Cellulose, 273 Cement, 198 Cerasin, 274 Cerebrote, 317 Cerussite, 219, 222 Chal cocite, 225 Chalcopyrite, 225 Chalk, 200 “ prepared, 200 Charcoal, 167 “ animal, 167 “ wood, 167 Charles, law of, 19 Chemical affinity, 14, 38 “ elements, definition of, 63 “ elements, table of, 64 “ equations, 85 “ notation, 71 “ physics, 16 “ reactions, 83 “ “ rules for, 85 “ symbols, 71 Chemicals, solubility of, 337 Chemism, 13, 38 364 INDEX Chemistry, definition of, 9 “ inorganic, 89 “ organic, 243 “ theoretical, 63 Chloral, 257, 327 “ hydrate, 257 Chloride of lime, 198 Chlorine, 112, 131 “ oxides, 115 “ hydride, 114 Chloroform, 260 “ physiological effects, 261 ‘‘ vapors, 327 Chlorophyll, 316 Cholepyrrhin, 313 Cholesterin, 312 Chondrin, 311 Chromates, 209 “ toxicology, 210 Chrome, alum, 209, 240 “ iron, 208 “ yellow, 223 Chromic anhydride, 208 “ cnlorides, 209 “ oxide, 208 “ trioxide, 208 Chromium, 208 “ alums, 209 “ oxides, 208 “ sulphates, 209 Chrdmous chlorides, 209 Chyle, composition of, 330 Cinehonidine, 298 Cinchonine, 297 Cinnabar. 229, 233 Citrates, 286 Classification of elements, 89 Coal, 168 “ anthracite, 168 “ bituminous, 168 “ gas, 169 Cobalt, 218 “ compounds of, 219 Cobaltic compounds, 219 Cobalt ite, 219 Cobaltous compounds, 219 Cocaine, 298 Cochineal, 316 Cocculus Indicus, 327 Codeine, 298 Cohesion, 18 Coil, induction, 46 Coke, 168 Colchicine, 298 Colcothar, 215 Colic, painters’, 223 Collagen, 311 Collodion, 273 “ flexible, 273 “ styptic, 273 Colloids, 57 Colophony, 252 Coloring matters, vegetable, 315 Combustion, 95 “ moist, 106 Compound body, 63 Compounds, 76, 317 “ scale, 285 Conductors, resistance of, 43 Conglutin, 310 Coniferin, 301 Conine, 298 Convolvulin, 301 Convulsives, 324 Copal, 252 Copperas, 214 Copper, 224 acetates, 228 “ arsenite, 227 “ carbonates, 227 “ physiological action, 228 “ pigments, 228 “ pyrites, 225 “ sulphate, 227, 325 “ stone, 225 Corrosive sublimate, 326 Corundum, 238 Cotton, gun, 273 Cream of tat tar, 193 Crocin, 316 Crocoisite, 219 Crystallin, 307 Crystallizations, 57 “ water of, 59 Crystals , system of, 59 “ forms of, 57, 59 Crystalloids, 58 Crystallography, 57 Culinary paradox, 24 Cupric compounds, 226 Cuprite, 225 INDEX. 365 Cuprous compounds, 225 Currents, extra, 47 “ Faradic, 47 “ induced, 45-47 “ interrupted, 47 “ secondary, 47 “ thermo-electric, 49 Cyanides, 176 “ compound, 179 “ toxicology, 177 Cyanogen, 176 Cynogene, 248 DAPHNIN, 296 Decimal system, 14 Definite proportion, law of, 92 Deliquescence, 55-59 Deliriants, 324 Density, 11 Deodorizers, 132 Deoxidation, 93 Deposit, lateritious, 291 Depressants, 324 Dew point, 130 Dextrin, 272 Dextrogyrate, 268 Dextrose, 270 Dialysates, 57 Dialyser, 57 Dialysis. 57 Diamond, 166 Diastase, 318 “ pancreatic, 318 Dicalcium phosphate, 200 Diffusion, 21, 55 “ of gases, 20 “ of liquids, 56 “ Graham’s law of, 21 Digestion, 110 Digitalin, 302 Digitalis, 327 Dihydro phenol, 288 Dimethyl oxichinine, 297 Dimorphism, 59 Dipotassium sulphate, 192 Disinfectant, Lanande’s, 133 Disinfectants, 132 “ commercial, 134 Disodium phosphate, 184 “ tetraborate, 185 Distillation, 25 Distillation, destructive, 25 “ fractional, 25 Dolomite, 203, 205 Drummond light, 193 Dualine, 266 Dulcite, 266, 267 Dulcose, 267 Dynamite, 266 Ebonite, 250 Efflorescence, 59 Electrical induction, 37 “ tension, 40 “ current or circuit, 39 Electricity, 36 effects of, 51 extra current, 47 frictional or static, 50 “ magneto-, 48 “ resistance of conduc- tors of, 43 secondary or induced currents, of, 45-47 Electro-negative, 89 Electro-metallurgy or plating, 52 Electro-motor force, 40 Electro-positive, 89 Electrodes, 45 Electrolysis, 51 Elements, chemical, definition, 63 “ classification of, 89 “ non-metallic, 90 “ typical, 91 Elutriation, 200 Emery, 238 Emetics, 325 Emulsin, 318, 319 “ ferment, 318 Enzymes, 318 Epsom salt, 204 Equations, 85 Equivalence, 71 Esculin, 302 Esculetin, 302 Eserine, 298 Essence of mirbane, 293 Ether, 327 “ acetic, 276 “ ethyl, 275 “ luminiferous, 29 “ methyl acetic, 260 366 INDEX. Ether, nitrous, 276 “ sulphuric, 275 Ethers, 256-274. “ compound, 256 “ haloid, 256 “ mixed, 256 “ simple, 256-274 “ vinic, 275 “ of glyceryl, 304 Ethyl alcohol, 261 “ benzoate, 276 “ butyrate, 276 “ nitrate, 276 “ nitrite, 276 “ oxide, 274 “ valerianate, 274 Ethylene, 248. Eucalyptine, 251 Eucalyptol, 251 Evaporation, 25 Extension, 14 Extract, Goulard’s, 223 “ pear, 277 “ pineapple, 277 “ strawberry, 277 Fats, 304 Fehling’s solution, 270 Fermentation, alcoholic, 261, 321. “ butyric, 322 “ lactic, 322 “ putrefactive, 322 Ferment, acetic acid, 321 “ albuminoid, soluble, or unorganized, 318 “ alcoholic, 321 “ curdling, 318 emulsion, 318 “ lactic, 282 “ organized, 321 Ferric alum, 216 “ chloride, 216 “ compounds, 215 “ hydrate, 216 “ nitrate, 217 “ oxide, 215 “ phosphate, 218 tl pyrophosphate, 218 “ sulphates, 216 Ferricyanides, 179 Ferrocyanides, 179 Ferrous carbonate, 214 “ chloride, 214 “ compounds, 214 “ hydrate, 214 “ iodide, 214 “ lactate, 215, 283 “ oxalate, 215 “ oxide, 214 “ phosphate, 215 “ sulphate, 214 “ sulphides, 215 “ tartrate, 215 Fibrin, 307 “ muscle, 307 Fibrinogen, 307 Fibrinoplastin, 307. Fire damp, 247 Flavin, 302 Fluid, Burnett’s, 133, 326 “ Condy’s, 133 “ soldering, 326 Fluor spar, 111 Fluorine, 111 Force, 16 “ electro motor, 40 “ heat, 16 Forces, physical, 11 “ polar, 37 Formulas, empirical, 73 graphic, 73 “ rational, 73 Fowler’s solution, 152 Frauenhofer’s lines, 34 Fraxin, 302 Freezing point, 23 Fruit flavors, artificial, 277 Fusel oil, 264 Galactose, 271 Galbanum, 253 Galena, or galenite, 219 Galvanic cell, theory of, 38 “ current, 52 Gamboge, 253 Gas, air, 170 “ coal, 169 “ “ composition of, 170 “ marsh, 247 “ olefiant, 248 “ water, 170 Gasoline, 170, 248 INDEX. 367 Gasometer, 169 Gases, constitution of, 17 “ diffusion of, 20 “ poisonous, 327 Gastric juice, analysis of, 330 Gelatin, 311 Germicides, 132 Gersdorffite, 218 Giant powder, 266 Glass, 166 “ soluble or water, 166 Glauber’s salt, 182 Globulin, 307 Globulins, 306 Glucoses, 267 Glucosides, 301 Glue, 311 Gluten, 310 Glycerine, 256 “ nitro, 266 Glycerines, 265 Glycerrhicin, 302 Glyceryl trinitrate, 266 Glycocin, 310 Glycogen, 272 Glycol, 256 Gmelin’s test, 314 Gold, 237 “ trichloride, 238 Goulard’s extract, 223 Graham’s law of diffusion, 21 Gramme, definition, 15 Grape sugar, 270 Graphite, 166 Gravitation, definition of, 11 “ law of, 11 Gravities, specific, table of, 336 Gravity, specific, 11 “ “ flask, 12 Greenockite, 207 Green, Brighton, 229 “ Brunswick, 228 “ mineral, 228 “ mountain, 228 “ Neuwieder, 228 “ Paris. 227 “ verditer, 228 Guaiacum, 252 Guanin, 318 Gum Arabic, 274 “ bassorin, 274 Gum, British, 272 “ lac, 253 “ resins, 252 “ Senegal, 274 “ tragacanth, 274 Gums, 252, 274 Gun cotton, 273 “ powder, 191 Gutta percha, 250 Gypsum, 199. HiEMATIN, 308 hydrochloride, 308 Haemin, crystals, 308 Haemoglobins, 308 Haematite, 212, 215 Halogen elements, 111 Hausmanite, 210 Heat, 22 11 latent, 26 “ sensible, 28 “ specific, 27 Hematoidin, 313 Hematoxylon, 316 Heavy spar, 202 Helleborein, 302 Helleborin, 302 Hemipeptone, 310 Hemlock, 327 Histozym, 318, 320 Homologous series, 245 Hornblende, 203 Hydrates, 77 Hydric chloride, 114 “ sulphate, 122 Hydrobilin, 314 Hydrobilirubin, 314 Hydrocarbons in air, 131 “ radicals, 255 “ homologous, no- menclature of, 247 “ homologous series of, 245 “ isologous series of 245 Hydrogen, 91 “ alcoholic, 258 “ and nitrogen, 134 “ and oxygen, 97 “ antimoniuretted, 158 “ arsenides, 150 368 INDEX. Hydrogen, arseniuretted, 150 “ basic, 77 chloride, 114 disodium phosphate, 184 “ fluoride, 111 “ light carburetted, 247 “ oxide, 97 “ peroxide, 110 “ phosphoretted, 146 “ sodium carbonate, 184 “ phosphate, 183 “ sulphate, 125 sulphuretted, 122 ammonium carbonate, 195 Hydrometer, 13 “ Twaddell, 13 Hydropotassium, carbonate, 191 “ oxalate, 192 “ sulphate, 192 tartrate, 193 Hydroquinone, 288 Hydrosodium sulphate, 183 Hydroxylamine, 136 Hygroscopic, 59 Hyoscyamine, 298 Hyponitrous oxide, 137 Hypothesis, definition of, 9 Hypoxanthine, 318 Hyposthenisants, 324 ICE, 99 _ Illuminating gas, 169 India rubber, 250 Indican, 302, 315 Imides, 291 Indigo, 315 “ carmine, 315 Indigotin, 315 Indium, 238 Induction, electrical, 37 “ coil, 46 Inebriants, 324, 327 Inertia, 14 Infectious diseases, 327 Infusion, 110 Inosite, 271 Invertin, 318-320 Iodine, 117, 326 “ compound tincture, 189 Iodine, oxides, 119 Iodoform, 261 Iridium, 240 Iron. 212, 326 “ cast, 213 “ chlorides. 216 “ chrome, 208 “ citrates, 217, 218 “ oxides, 214, 215 “ phosphates, 218 “ pig, 213 “ scale compounds of, 217 “ sulphates, 214 “ tartrates, 217 “ wrought. 213 Isomeric bodies, 246 Isomerism, 245 JALAPIN, 301 Jeweler’s rouge, 215 KALIUM, 187 Kephalins, 317 Kermes’ mineral, 160 Kerosene, 248 Ketones, 258 Kreatin, 317 Kreatinin, 317 LABAREAQIJE’S solution, 186 Lac sulphuris, 122 Lactometer, 13 Lsevogyrate, 268 Lampblack, 167 Lana philosophica, 206 Lanthopine, 298 Lapis infernalis, 236 Lardacein, 310 Laudanine, 298 Laudanosine, 298 Laudanum, 326 Laughing gas, 137 Law of Ampfere, 17, 66 Avogadro, 17, 66 “ Berthelet, 84 “ Charles, 19 “ definite proportions, 92 “ Graham’s, 21 11 19 “ Ohm’s, 44 Leaching, 110 INDEX. 369 Lead, 219,326 “ acetates, 223 “ binoxide, 221 “ carbonate, 222 “ chlorides, 221 “ chromate, 223 “ dioxide, 221 “ iodide, 222 “ 'nitrate, 222 “ oxides, 220 “ peroxide, 221 “ plaster, 221,282 “ puce oxide, 221 “ red, 221 • “ sugar of, 223, 326 “ sulphate, 222 “ sulphide, 223 white, 222, 326 Lecithin, 317 Legumin, 310 Lfepidolite, 180 Leucin, 317 Levulose, 270 Light, 29 “ chemical effects of, 36 • “ table of calculation of color and intensity of, 31 “ transmission of, 30 Lignin, 273 Lime, 197 “ chloride of, 198 “ milk of, 198 “ slacked, 198 “ stone, 197 “ water, 198 Limonite, 212 Liniment, saponis, 251 Liquorice sugar, 302 Liquor, 110 “ acidi arseniosi, 152 “ ammoniae, 135 “ ammon. acetatis, 196 “ arsenii et hydrarg. iodidi, 151 “ calcis, 198 “ ferri chloridi, 216 “ “ nitratis, 217 “ “ perchloridi, 216 “ subsulphatis, 216 “ hydrargyri nitratis, 233 “ mother, 58 Liquor plumbi subacetatis, 223 “ potass, arsenitis, 152 “ sod® arsenatis, 153 “ “ chloratae, 186 Liquors, distilled, 263 u fermented, 263 re expressed each day, for a manual as complete, yet more con- densed and therefore easier for reference, than a Dispensatorv, more exhaustive than the Pharma- copoeia, and containing in a limited space the elements of a text-book on materia medica and phar- macy, at once useful to the druggist and physician. “In clearness of style, simplicity of classification, and preciseness of directions, the treatise is indeed a model, and will be found alike instructive and useful for the physician and druggist.”— American Chemical Review. “ It is really the most modern of works; its terseness is commendable; its synoptical and directness of arrangement lends worth to the practitioner, dispensing pharmacist and the reviewer.”—St. Louis Medical Journal. 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THE MICROSCOPE. “ The author very carefully brings out every necessary fact and principle relating to the use of the microscope, and now that this instrument has become an essential part of every practitioner’s arma- mentarium, a practical guide and reference hook is also a necessity, and we are fully warranted in reiterating the statement that this is one of the most valuable text-books ever offered to students and practitioners of medicine.”—The Cincinnati Lancet and Clinic. GENEliAL AND SCIENTIFIC BOOKS. MARTIN’S MANUAL OF MICROSCOPIC MOUNTING. With Notes on the Collection and Examination of Objects, an upwards of 150 Illustrations. By John II. Martin. Second Ed] tion, Enlarged. 8vo. Cloth, $2.7 INDIGESTION, HEALTH, HEADACHES, ETC. BEALE OK SLIGHT AILMENTS. New Edition. Just Ready. Slight Ailments, Their Nature and Treatment. By Lionel S Beale, m.d., f.r.s., Professor of Practice, King’s Medical College London. Second Edition. Enlarged anel Illustrated. Cloth, |1.25 ; Paper Covers, .7 Better Edition, Heavy Paper. Extra Cloth, $1.7 OUTLINE OF CONTENTS. Introductory. The Tongue in Health and Slight Ailments. Appetite. Nausea. Thirst. Hunge, Indigestion, its Nature and Treatment. Constipation, its Treatment. Diarrhoea. Vertigo. Gidd ness. Biliousness. Sick Headache. Neuralgia. Rheumatism. The Feverish and Inflammatoij State. Of the Actual Changes in Fever and Inflammation. Slight Inflammations, etc., etc. “A valuable work for the family library.”—Bos/on Transcript. “ Clear, practical and a valuable instructor.”—Baltimore Gazette. : “An admirable treatise upon the minor ills which flesh is heir to.”—Springfield Republican. GILL. ON INDIGESTION. Third Edition. Indigestion : What It Is ; What It Leads To ; and a new Metlioi of Treating it. By John Beadnell Gill, m.d. Third Edition! 12mo. Cloth, $1.2 DAY ON HEADACHES. Fourth Edition. The Nature, Causes, and Treatment of Headaches. Fourth Edi tion. Illustrated. By Wm. Henry Day, m.d. Octavo. 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IEALTHY SKIN. Eighth Edition. A Practical Treatise on the Skin and Hair ; their Preservation and Management. By Eras- mus Wilson, m.d., f.r.s. Eighth Edition. 12mo. Paper. Price, $1.00 IUFELAND, LONG LIFE. The Art of Prolonging Life. By C. W. Hufeland. Edited by Erasmus Wilson, m d. 12mo. Cloth, $1.00 “ We wish all doctors and all their intelligent clients would read it, for surely its perusal would be ttended with pleasure and benefit.”—American Practitioner. MISCELLANEOUS. \ EM AT AGE’S VETERINARIANS’ POCKET REMEMBRANCER. Containing concise directions for the Treatment of Urgent or Rare Cases, embrac ng Semeiology, Diagnosis, Prognosis, Surgery, Therapeutics, Detection of Poisons, Hygiene, etc., of the Horse. New Revised Edition. 18mo. Cloth, $1.25 \NSTIE, STIMULANTS AND NARCOTICS. With special researches on the Action of Alcohol, Ether and Chloroform on the Vital Organism. Bv Francis E. Anstie, m.d. Svo. Cloth, $3.00 GENERAL AND SCIENTIFIC BOOKS. YEO’S MANUAL OF PHYSIOLOGY. 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The Opium, Morphine, Chloral, Hashisc and Similar Habits. By H. H. Kane, m.d., of New York. Wit Illustrations. Paper, .75 ; Cloth, $1.2 MILLER, ON ALCOHOL. Alcohol. Its Place and Power. By James Miller. Cloth, .£ LIZARS, ON TOBACCO. The Use and Abuse of Tobacco. By John Lizars, m.d. Cl., .1 The above Two Volumes bound in One. Cloth, $1.0 PARRISH. ALCOHOLIC INEBRIETY. Alcoholic Inebriety from a Medical Standpoint, with Ulustrativ Cases from the Clinical Records of the Author. By Joseph Pai rish, m.d., President of the American Association for the Cure < Inebriates. 12mo. Paper Covers, .75 ; Cloth, $1.2 ACTON. THE REPRODUCTIVE ORGANS. The Functions and Disorders of the Reproductive Organs i Childhood, Youth, Adult Age and Advanced Life, considered i their Physiological, Social and Moral Relations. By Willia Acton, m.d., m.r.c.s. Sixth Edition. 8vo. Cloth, $2.C “In the work now before us, all essential detail upon its subject matter is clearly and scientificai given. 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Sixth Edition. A Manual of Practical Hygiene. By Edward A. Parkes, m.d. The Sixth Revised and Enlarged Edition. With Many Illustra- tions. 8vo. Cloth, S3.00 1 It is the most complete work on Hygiene which we have seen.”—New York Medical Record. ‘ It never fails to throw light on any hygienic question which may be proposed.”—Bosion Medical <1 Surgical Journal. ‘ We commend the book heartily to all needing Instruction in Hygiene.”—Chicago Medical Journal. GENERAL AND SCIENTIFIC BOOKS. 15 WILSON’S TEXT-BOOK OF DOMESTIC HYGIENE AND SANI- TARY INFORMATION. A Guide to Personal and Domestic Hygiene. By George Wil- son, :>?.d., Medical Officer of Health, etc. Edited by Jos. G. Rich- ardson, m.d., Professor of Hygiene at the University of Pennsyl- vania. 314 pages. 12mo. Cloth, $1.00 Chapter i.—Introductory, page 17. n. The Human Body, 33. in. Causes of Disease, 66. iv. Food and Diet, 119. v. Cleanliness and Clothing, 169. vi. Exercise, Recreation and Training, 187. vii. Home and Its Surroundings, Drainage, Warming, etc., 221. vm. Infectious Diseases and their Pre- vention, 269. “A most useful, and in every way, acceptable book.”—New York Herald. “Marked throughout by a sound, scientific spirit, and an absence of all hasty generalizations, sweeping assertions, and abuse of statistics in support of the writer’s particular views. . . . We can- not speak too highly of a work which we have read with entire satisfaction.”—Medical Times and Gazette. BIBLE HYGIENE ; Or, Health Hints. By a Physician. This book has been written, first, to impart in a popular and condensed form the elements of Hygiene ; second, to show liow varied and important are the Health Hints contained in the Bible, and third, to prove that the secondary tendency of modern Philosophy runs in a parallel direction with the primary light of the Bible. 12mo. 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