LIBRARY OF CONGRESS. Chap._^-„. Copyright No._ SheitZM/.:; UNITED STATES OF AMERICA. ESSENTIALS OF MEDICAL AND CLINICAL CHEMISTRY. WITH LABORATORY EXERCISES. BY SAMUEL E. WOODY, A.M., M.D. FOURTH EDITION REVISED AND ENLARGED. ILLUSTRATED. PHILADELPHIA : P. BLAKISTON'S SON & CO., 1012 Walnut Street, 1900. *> 028 TWO copita H^c&ivfio, Library 0/ Congret* Office of th* JUN8-19G0 Itffllttr of Copyright* SECOND COPY. 62525 Copyright, 1900, by P. Blakiston's Son & Co. Press of "VVickeisham P. in ting Co., Lancaster, Pa. PREFACE TO FOURTH EDITION. In this Fourth Edition the text has been largely re-written, especially the clinical portion, and much new matter added. Realizing the need of a brief text-book that would also serve as a practical laboratory guide, the author has, wherever the directions in the text are not sufficiently explicit, added, as foot-notes, a series of simple laboratory exercises embodying such experiments as he has had his students perform during his twenty years of med- ical laboratory teaching. It will be noticed that the experiments are so simple as to require only such apparatus as the general practi- tioner has, or should have, about his office. In keeping with the present pharmacopoeia, the old spelling is retained. Thanks for valuable assistance is extended to the author's col- leagues, Drs. Solomon, Rominger and Rapp, Professors of Materia Medica, Inorganic Chemistry, and Organic and Clinical Chem- istry, respectively, in the Medical Department of Kentucky University ; to Dr. Harris M. Kelty, Professor of Chemistry in the Louisville Medical College, and to Dr. fas. Lewis Howe, Professor of Chemistry in Washington and Lee University. This edition is presented with the hope that it may meet as cordial a reception as its predecessors, and that teacher and student will find the author's labor has lightened theirs. 600 West Broadway, Louisville, June, igoo. (in) TABLE OF CONTENTS. PAGE INTRODUCTION 9-17 Definition of chemistry, 9; properties of matter, 11 ; specific gravity, 10; states of matter, 14; table of elements and atomic weights, 15; atomic theory, 16; symbols, formulae, equations, 17. PART I.— INORGANIC CHEMISTRY 18-132 Classification of the Elements 19 I. Preliminary Group • I 9~3 I Hydrogen, 19; oxygen, 21; ozone, 23; water, 25; natural waters, 27; purification of water, 29; hydrogen dioxide, 30; ("Radicals, 31 : affinities, 32; valences, 34; nomen- clature, 36.) II. Chlorine Group 37~44 Fluorine, Chlorine, Bromine, Iodine, 37. (Nomenclature of acids and salts, 40.) Hydracids of chlorine group, 41 ; oxysalts of chlorine group, 43. III. Sulphur Group 44~5 1 Oxygen, 21; Sulphur, 45 : hydrogen sulphide, 46; carbon disulphide, 48; sulphur dioxide, sulphur trioxide, 49; sulphuric acid, 50; Selenium, Tellurium, 44. IV. Nitrogen Group 5 2_ 7 2 Nitrogen, 52: the atmosphere, 53: (Argon, Helium, Kryp- ton, Neon, 55); ammonia, 55; nitrogen monoxide, di- oxide, trioxide, 58; tetroxide, pentoxide, 59. Phosphorus, 60: hydride, 61; oxides and oxacids, 62. Arsenic, 63: arsine, 64; arsenous iodide, sulphide, oxide, 64; arsenic oxide, 65; toxicology of arsenic, 65. Antimony, 69: stibine, 69; oxide, sulphide, 70; tartar emetic, 70; toxi- cology of antimony, 70. Bismuth, 71 : nitrate, subnitrate, subcarbonate, 71. V. Carbon Group 72-86 Carbon, 73: monoxide, 74; dioxide, 75; ventilation, 78; cyanogen, 79; cyanides, 80. Silicon, 81 : oxide, 81; silicates, 81; (The Metals, 81). Tin, 82. Lead, 82: oxides, nitrate, acetate, 83; chloride, sulphate, carbonate, 84; sulphide, iodide, chromate, toxicology of, 85. (v) VI CONTENTS. PAGE VI. Potassium Group 86-97 Hydrogen, 19; Lithium, 86; Ammonium, 87; hydrate,87; sulphide, carbonate, etc., 88. Sodium, 89 : chloride, 89; dioxide, bicarbonate, etc., 90. Potassium: carbon- ate, acid salts, 91; bicarbonate, bitartrate, hydrate, 92; iodide, bromide, nitrate. 93; hypochlorite, 94; tests, 96. Caesium, Rubidium, 96. ( Acidimetry and Ukalimetry, 96.) VII. Calcium Group 97-102 Calcium, 98: chloride, carbonate, oxide, 98; hydrate, hypo- chlorite, sulphate, phosphate, oxalate, 99; carbide, hard- waters, 100. Strontium, ici. Barium, 10 1. VIII. Magnesium Group 102-106 Magnesium, 102: sulphate, 102; citrate, carbonate, oxide, hydrate, phosphates, 103. Zinc, 104: sulphate, chloride, 104; carbonate, oxide, sulphide, 105. Cadmium, 106. IX. Aluminum Group 106-109 Boron, 106: boric acid, borax, 107. Aluminum, 107: oxide, hydrate, chloride, sulphate, alum, ic8; silicates, 109. Cerium, 109. Scandium, Gallium, Yttrium, Indium, Lanthanum, Neodymium, Praseodymium, Samarium, Er- bium, Ytterbium, Thallium, 106. X. Iron Group 1 10-1 18 Chromium, no: oxides, chromates, no; bichromates, in. Manganese, ill: dioxide, sulphate, ill; sulphide, man- ganates, permanganates, 112. Iron, 112: reduced, 113; chlorides, sulphates, 114; hydrates, 115; nitrate, iodide, carbonate, sulphide, scale preparations, 116. Cobalt, Nickel, Molybdemum, Tungsten, Uranium, 117. XL Copper Group ... 1 18-129 Copper, 118: sulphate, hydrates, 119; oxides, subacetate, 120. Mercury, 121 : iodides, nitrates, sulphates, 122; chlorides, 123; oxides, oleate, sulphides, tests, 124. Silver, 126: nitrate, oxide, 126; cyanide, chloride, bromide, iodide, 127. Gold, 128. (Platinum, etc., 129.) Analytical Tables: metallic radicals, 130; acidulous radicals, 131 ; solubilities, 132. PART II.— ORGANIC CHEMISTRY *33-i79 General Considerations: definition, 133; peculiarities of carbon com- pounds, 133; homologous and isologous series, 134; ultimate analysis, 135; molecular formulae, =36. CONTENTS. Vll PAGE Hydrocarbons 1 37-144 Table of classification, 137. Methane Series, 138, 139: petroleum, 138; methane, ethane, 139. Methane Series, 139: ethene, 139. Ethine Series, 139: acetylene, 139. Tritone Series, 140 : volatile oils, resins, 140; camphors, caout- chouc, gutta-percha, 141. Benzene Series: 141 : benzene, toluene, naphthalene, 142. Halogen Derivatives, 142: chloroform, 142; bromoform, 143; iodoform, 144. Alcuhols and their Derivatives 144-163 Methyl Series, 144: table, 144. Alcohols: methyl alcohol, 145; ethyl alcohol. 146; amyl alcohol, sulphur alcohols, 148. Ethers, 149: definitions, ethyl ether, 149, ethyl chloride, 150: ethyl bromide, ethyl nitrite, pentyl nitrite, 151. Aldehydes, 151 : methyl aldehyde, ethyl aldehyde, chloral, 152. Organic Acids, 153: formic, acetic, 153; butyric, valerianic, 154; palmitic, stearic, oleic, 155. Table of homologous series of fat acids, 156. Methene Series, 157: oxalic acid, 157; lactic acid, succinic acid, malic acid, tartaiic acid, citric acid, 158. Methenyl Series, 158: glycerine, 159; nitroglycerine, 159. Benzene Series, 159: Phenol, 159; resorcin, creasote, guaiacol, 160; cresol, salol, salophen, saccharin, 161. Aromatic Acids: benzoic, picric, 161; salicylic, gallic, pyrogallic, 162. Carbohydrates 163-168 Amyloses, 163: cellulose, 163; gums, starch, 164; dextrin, gly- cogen, 165. Saccharoses, 166: cane sugar, milk sugar, 166; maltose, 167. Glucoses, 167: glucose, 167; Isevulose, 168. Glucosides 1 68, 1 69 Amygdalin, salkin, 168; tannin, myronic acid, indican, etc., 169. Ammonia Substitution Compounds 169-172 " -Amines " and "-amides," aniline, 170; trimethylamine, acetan- ilide, phenacetine, antipyrine, 171. Proteids 1 72-1 75 Natural albumins, globulins, 173; derived albumins, 174; fibrins, peptones, albumoses, coagulated proteids, lardacein, 175. Alkaloids 1 75-1 79 Natural alkaloids, 175; ptomaines, 176; leucomaines, bacterial proleids, antitoxme, 178; table of alkaloids, 179. Vlll CONTENTS. PAGE PART III.— CLINICAL CHEMISTRY 180-228 I. The Urine . 180-216 Definition, mechanism, 180; selection of a specimen, 181. Physical Properties. Description of normal urine, var- iability in health and in disease, quantity, 181 ; transparency, 182; fluidity, color, odor, reaction, 183; acid and alkaline fermentations, 185. Specific gravity, 186; estimation of solids in. urine, 187. Normal Constituents. Urea, 188; methods of estimation, 190-192. Kreatine, Kreatinine, Xanthine, Allantoin, Uric acid, 192; Coloring matters, 194; Phosphates, 195; Chlor- ides, 196; Sulphates, 197. Abnormal Urine. Albumin, 198; Tests: heat, nitric acid, Howe's, etc., 198; estimation, 199. Globulin, Albumose, Peptone, 200. Mucin, Sugar, 201; Tests: fermentation, 201; alkali, alkali-copper, Fehling's, Haines', 202; alkali- bismuth, picric acid, indigo-carmine, phenyl-hydrazine, 203; estimation, 204; Acetone, Diacetic Acid, Calcium, Oxalate, 205 ; Calcium Carbonate, Hippuric Acid, Bile, 206 : Test for bile coloring matters, 206; for bile salts, 207; Leucin, Tyrosin, Cystin, Blood, 208; Pus, 209; Fat, Epithelia, 210; Tube Casts, 211; Spermatozoa, Micro-organisms, 213; Ex- traneous Bodies, Calculi, 215. II. Milk 216-224 Description, 216; (Colostrum, 216;) Chemical constituents, 218. Casein, 218; Fat, Milk Sugar, 219; Salts, 220. Adulteration, 220. Milk Testing, 221 : hydrometer, lacto- scope, 221; centrifuge, Werner-Schmidt process, 222; clin- ical test, 224. Kumyss, 224. III. Saliva 224 Description, function, ptyalin, potassium sulpho-cyanate, 224. IV. Gastric Juice 225-228 Description, composition, pepsin, hydrochloric acid, 225. Test-meal, 225. Tests of stomach contents, 226 : litmus, congo-red, 226; free HC1 (Gunzburg's, Boas'), Uffelman's, rennet ferment, 227; butyric acid, acetic acid, 228; esti- mation of total acidity, of free HC1, of acid salts, 228. Ferments 229 Table of Metric Measures 230 Index 231 THE ESSENTIALS OF MEDICAL AND CLINICAL CHEMISTRY. INTRODUCTION. " Chemistry is that branch of science which treats of the com- position of substances, their changes in composition and the laws governing such changes." (Webster.) The distinctive characteristic of chemical action is change in composition} A piece of iron may undergo many and marked changes ; it may be made hard or soft, hot or cold, luminous or non-luminous, magnetized or unmagnetized ; yet, so long as there is no modification of its composition, the change is not a chemical one, and the iron is still iron. But when it combines w T ith other substances, as in rusting (combining with the oxygen of the air), the change is chemical and a new substance is formed which, though it contains iron, is not iron, but is entirely different in composition and properties. 2 NbTE. — It would be well for the professor or demonstrator at each labora- tory exercise to indicate beforehand, by means of the attached numbers, such of the experiments as he wishes performed. Each student should be required to have a note-book and make careful and full memoranda of everything he does. 1 Heat pieces of platinum and magnesium wire. Note that while the platinum is unaltered, the magnesium burns (combines with the oxygen of the air) and is converted into a white powder. 2 Suspend an ordinary hand-balance (Fig. i) from the upper ring of the retort-stand, so that the pans are about a half inch above a note-book laid on the lower and larger ring. 'Weigh out one gram of powdered iron; put it into a small dish made by bending up the edges and corners of a bit ol thin 2 (9) IO ESSENTIALS OF CHEMISTRY. Matter is that of which the sensible universe is composed. It is Indestructible. Substances may undergo many changes, assume a great variety of forms, and even become invisible and fleeting gases; yet in none of these changes and combinations can a particle of matter be created or destroyed. 8 Fig. i. Fig. 2. All matter has weight. By balances in the open air we get the apparent weight of a body ; but to obtain the ab- solute weight it must be weighed in a vacuum where there is no air to buoy it up. (For measures of weight, see table at back of book.) But of most importance to the student of chemistry is the specific weight or specific gravity, by which we mean the weight of a substance as compared with the weight of an equal volume of some other substance specified as a standard. It is not the weight of any particular body or piece of a substance, but the relative weight of that substance or material sheet iron or copper; heat it until it ignites. When combustion is complete, pour it again into the scale, and note that a new reddish-brown substance is formed, and that the weight is increased. 3 Let the instructor burn a piece of charcoal (carbon) in a jar of oxygen gas (Fig. 2). It disappears, and, so far as we can judge by the senses of sight and touch, is lost, for it has combined with the oxygen to form an invisible gas. Add lime water and shake. The gas combines with the lime and forms a white precipitate, which, if gathered and weighed, would exactly represent, besides the lime, the charcoal burned and the oxygen required to burn it. INTRODUCTION. I T wherever found. The standard for liquids and solids is water ; for gases it is hydrogen or air. To determine the specific gravity of a liquid, divide the weight of a certain volume of it by the weight of an equal volume of water, and thus obtain the ratio. 4 In practice we use : (a) The specific gravity flask (Fig. 3), made and marked to contain a certain number of grains or grams of water. Fill it up to the " scratch " on the narrow neck, with the liquid to be investigated, and weigh, deducting the weight of the flask. Divide the weight of the liquid by the marked capacity of the flask, (b) The hydrometer (Fig. 4), a hollow glass float with a graduated neck at the upper end indicat- dp^ ing the specific gravity by the depth to which it sinks in the liquid. 5 This instrument is often called by other names according to its use, as "lactometer" for milk and "urinometer" for urine. For very accurute measurements of specific gravity, the liquids must be at the standard tem- perature, which in this country is 6o° F. or i5-5 C The specific gravity of solids is determined on the principle of Archimedes : A body immersed in a liquid displaces its own volume, and loses weight equal to the weight of the liquid displaced. Therefore, the weight a body loses when weighed in water is the weight of its own volume of water, 4 Procure a light vial or a small flask of 5 or 10 Cc. (1 or 2 drams) capacity, make a scratch on the neck with a file and weigh. Fill up to the scratch with water and weigh, deducting the weight of the vial, (a) Fill again with some liquid, as alcohol, lighter than water and weigh, deducting the weight of the vial. Divide the weight of the vialful of alcohol by the weight of the vialful of water. The resulting ratio will be the specific gravity of the alcohol, (b) Repeat the experiment, using sulphuric acid (a heavy liquid) instead of alcohol. 5 Confirm the foregoing by using the hydrometer, first proving its accuracy by testing it in water and other liquids of known specific gravity. G. T/£.VAHfi-CD 12 ESSENTIALS OF CHEMISTRY. and the standard with which the weight of that body must be compared. In case the body is lighter than water, a sinker is attached and Fig. 5. the same method pursued, except that the loss of weight of the sinker is also obtained separately, and subtracted from the total loss to ascertain the loss of weight of the lighter body. 7 6 Procure a small piece of metal, as a key, or better still, an iron " jack," such as children play with, and weigh it. Next suspend it by a fine silk thread from one pan of the balance (Fig. 5) into a beaker of water, and weigh it while completely immersed. For an example we will suppose : The piece of iron weighs 150 grains. Suspended in water it weighs 130 " Loss (or weight of its volume of water) 20 " Specific gravity of the iron (150-^-20) , . . . 7.5 7 Secure a piece of a small spermaceti candle; weigh it alone, and then INTRODUCTION. 1 3 A body soluble in water may be weighed in some liquid of known specific gravity in which it is insoluble. ^ The specific gravity of a substance in fine particles or powder may be determined by comparing its weight with the weight of the water it displaces in a vessel of known capacity. 9 Matter exists in one of three states, solid, liquid, or gaseous. In the solid state the particles are held together so rigidly as to give the body a definite shape ; while in the liquid state the attrac- tion is so slight as to allow the particles to move freely upon each other and the body to take the shape of the vessel that contains it. In the gaseous state the mutual attraction of the particles is attach it to the piece of iron used in the previous experiment and weigh the combination, calculating the specific gravity as in the following example, in which we will suppose the candle weighs 85 grains: The combination (iron 150 grains and candle 85 grains) weighs 235 grains. The combination weighs in water 125 " Loss (the weight of the combination's volume of water), no " Deduct the weight of the piece of iron's " " " . 20 " The weight of the candle's volume of water . 90 " Weight of candle divided by weight of its water volume (85-^-90)= 0.95—the sp. gr. of spermaceti. 5 Make such an experiment as this: Suppose a lump of rock-candy weighs ico grains, and in turpentine 45.62 grains. Lcss=icc — 4;. 62=54.38 grains. 100—54.38— 1.84 the sp. gr. as referred to turpentine. Multiply this by .87, the sp. gr. of the turpentine, and we get 1.6 as the true sp. gr. of rock-candy or crystallized sugar. 9 Weigh out 50 grains of fine, clean, dry sand, such as is sold for canary birds, and pour it into the vial used in experiment 4. Fill with water and weigh: then calculate the specific gravity of sand as in the following example, in which the vial is supposed to hold just 96 grains of water : Weight of the sand - 50 grains. Weight of a vialf ul of water 96 u Total 146 " Weight of the vialf ul of water with the sand 124 " Weight of the water-volume of the 50 grains of sand - . . 22 " Weight of the sand divided by the weight of its water- volume (50^22-2.27) gives the specific gravity of sand ■ 2.27 14 ESSENTIALS OF CHEMISTRY. entirely overcome, and their distance from each other depends upon the pressure to which the gas is subjected. The term fluid is applied to anything capable of flowing, whether liquid o gaseous. It is highly probable that all substances, which are not decomposed by heat or cold, are capable of existing in all three states. Heat is absorbed and hence cold produced whenever the attraction between the particles is to be overcome, as in the pass- age of a substance from the solid to the liquid or from the liquid to the gaseous state. When the two solids, ice and common salt, are mixed, they form a liquid, and great cold is produced. 10 Perspiration in evaporating assumes the gaseous state, and absorbs in the change so much heat that the body is kept at its normal temperature in spite of the hottest weather. 11 On the other hand, when a substance passes from a rarer to a denser state it gives out again the heat absorbed in its passage in the opposite direction. If we examine the infinite variety of substances upon our earth we find most of them are compounds, i. e., they can be decom- posed into two or more other substances, distinct in their proper- ties from the substance from which they were derived and from each other. There are some substances which have never been de- composed. These are called elements. Only about seventy elements are at present known ; but, as our methods of investigation im- prove, this number may be increased by the discovery of other elements, or decreased by decomposing some of those now con- sidered elements. About one-half of these enter into the materia medica, and will be noticed in this work. 10 Fold tin-foil into the shape of a little dish; add powdered ice and salt. Spill a few drops of water on the table and set the dish in it. Note how quickly it is frozen fast to the table. 11 Pour a few drops of ether into the hand and note the cold produced by its rapid evaporation. Or let the instructor put a little water in such a dish as the one just mentioned, and throw a spray of ether against the sides;, the water is quickly frozen. INTRODUCTION. 15 TABLE OF ELEMENTARY BODIES, WITH THEIR SYMBOLS AND ATOMIC WEIGHTS. {The more imPorta?it are pri7ited in capitals.) Name. Aluminum, Antimony (Stibium), Argon, Arsenic, Barium, Bismuth, Boron, Bromine, Cadmium, Qesium, Calcium, Carbon, Cerium, Chlorine, Chromium, Cobalt, ... Columbium (Niobi- um) Copper (Cuprum), Erbium, Fluorine, Gadalinium, Gallium, Germanium, Glucinum (Ben- Ilium, Be) Gold (Aurum),. Helium, Hydrogen Indium, Iodine, Iridium, Iron (Ferrum), . Lanthanum, .... Lead (Plumbum, Lithium, Magnesium, . . . Manganese, Symbol. Atomic Weight. '■ Al 27 Sb 120 A 40 As 75 Ba 137 Bi 208 B 11 Br 80 Cd 112 Cs *33 Ca 40 C 12 Ce 132 CI 35- Cr 52 5 Co 59 Cb 93 Cu 634 E 166 F 19 Gd 157 Ga 70 Ge 72 Gl 9 Au 197 He 4.26, H 1 In 114 I 127 Ir 193 Fe 56 La « 39 Pb 207 Li 7 Mg 24 Mn 55 Name. Mercury (Hydrargy- rum) , Molybdenum. Neodymium, Nickel, Nitrogen, Osmium, Oxygen, Palladium, Phosphorus, Platinum, Potassium (Kalium), Praseodymium, Rhodium, — Rubidium, Ruthenium, Samarium, Scandium, Selenium, Silicon, Silyer (Argentum),. Sodium (Natrium),.. Strontium, Sulphur, Tantalum, Tellurium, Terbium, Thallium, Thorium, Tin (Stannum), Titanium, Tungsten, or Wolfram Uranium, c Vanadium, Ytterbium, Yttrium, Zinc, Zirconium, q tt „ v 1 Atomic Symbol. Weight> Hg Mo Nd Ni N Os O Pd P Pt K Pr Rh Rb Ru Sm Sc Se Si Ag Na Sr S Ta Te Tb Tl Th Sn Ti W U V Yb Y Zn Zr 200 96 141 59 14 191 16 106 3i J95 39-i 144 104 85 101 l S° 44 79 28 108 23 87.5 32 182 125 160 204 233 118 5° 184 240 5 J -2 *73 90 65 90 To explain the laws governing chemical phenomena, modern chemistry has adopted and greatly amplified the old atomic theory — a theory advanced certainly as far back as the ancient Greeks, for Democritus, 460 B. C, said : "The atoms are invisible 1 6 ESSENTIALS OF CHEMISTRY. by reason of their smallness ; indivisible by reason of their solid- ity; impenetrable and unalterable." We will take up the theories and laws, not in the order of their enunciation, but of their natural sequence. It is assumed that matter is composed ultimately of infinitely small particles called atoms ; that each element is composed of atoms, all of a certain size, weight, etc. Atoms rarely exist alone, but in groups called molecules. In an element the molecule is generally composed of a pair of atoms of the same kind ; in com- pounds, of two or more atoms of different kinds. It has been de- termined that equal volumes of all substances in the gaseous state, and under like conditions, contain the same number of molecules. So a gallon of hydrogen gas and one of oxygen gas contain the same number of molecules, and those molecules consisting of pairs of atoms, each gallon must contain the same number of atoms. Furthermore, it is found that the gallon of oxygen is sixteen times as heavy as the gallon of hydrogen. So each oxygen atom must be sixteen times as heavy as the hydrogen atom. Hydrogen being the lightest substance known, its atomic weight is taken as i, and con- sequently the atomic weight of oxygen is 1 6. The atomic weights of other elements are determined in a similar way. By " atomic weight" is not meant the absolute weight of atoms (for that is not known), but the weight of the atom compared with the hydrogen atom. The atomic weight of carbon is 12. If carbon combines with oxygen, atom for atom, the new substance (CO) resulting from that action will consist of molecules, in each of which the carbon will weigh 12 and the oxygen 16, and, as the whole mass is composed of these molecules, the same proportion obtains throughout the new compound. So 12 is found to be the com- bining weight of carbon, and 16 of oxygen. If, however, the combination should occur in the proportion of one atom of carbon to two atoms of oxygen, then each molecule must consist of 12 by weight of carbon to 32 of oxygen, and that must be the proportion throughout the entire substance. Between these two compounds of a carbon atom with oxygen INTRODUCTION. 1 7 no intermediate one can occur, for the carbon atom must take one or two, or more, oxygen atoms. It cannot take a fraction of one, for atoms are indivisible. Hence, we deduce the following Law : Substances combine in certain fixed proportions (atomic weights) or in multiples of these proportions. Symbols are abbreviations of the names of the elements. They consist of the initial letter of the Latin name ; but if the names of several elements begin with the same letter, the single-letter sym- bol generally is reserved for the most common element, and for the others another letter is added. Thus, we have nine elements whose names begin with C ; the most common is carbon, whose symbol is C ; the others add other letters, as chlorine, CI ; cobalt, Co j copper (cuprum), Cu, etc. The symbol indicates just one atom. When more than one atom is to be represented, the num- ber is written just after and below the symbol, thus, C 4 . Formuloz are to molecules what symbols are to elements. They indicate the kind and number of atoms composing the molecule. When more than one molecule is to be indicated, the number is placed in front of the formula, thus, 5H9O. A parenthesis in- closing several symbols or formulae should be treated as a single symbol, thus, 2(NH 4 ) 2 C0 3 = N,H 16 C 2 6 . An equation is a combination of formulae and algebraic signs to indicate a chemical reaction and its results. As no matter is ever lost or created in a reaction, the number of each kind of atom before the equality sign must be the same as after it. PART I.— INORGANIC CHEMISTRY. Classification of the Elements. — The elements are usually divided into two great classes : (a) Metals, about fifty-five in number, possessing a peculiar lustre, good conductors of heat and electricity, and whose oxides when combined with water, form bases; (b) Non-metals, about fifteen in number, possessing but little lustre, relatively poor conductors of heat and electricity, and whose oxides combined with water form acids. The following classification is somewhat arbitrary, but convenient, and based mainly on chemical analogies, especially in valences and atomic weights. I. Preliminary Group : Hydrogen and Oxygen. II. Chlorine Group: Fluorine, Chlorine, Bromine, and Iodine. III. Sulphur Group: (Oxygen) Sulphur, Selenium and Tel- lurium. IV. Nitrogen Group: Nitrogen, Phosphorus, Arsenic, Anti- mony and Bismuth. V. Carbon Group: Carbon, Silicon, Tin, Lead, Platinum, Iridium, Osmium, Palladium, Ruthenium and Rhodium. VI. Potassium Group: Lithium, Ammonium, Sodium, Potas- sium, Rubidium and Caesium. VII. Calcium Group: Calcium, Strontium and Barium. VIII. Magnesium Group:. Magnesium, Zinc and Cadmium. IX. Aluminum Group: Boron, Aluminum, Scandium, Gal- lium, Yttrium, Indium, Lanthanum, Cerium, Neodymium, Praseo- dymium, Samarium, Erbium, Ytterbium and Thallium. X. Iron Group: Chromium, Manganese, Iron, Cobalt, Nickel, Molybdenum, Tungsten and Uranium. XL Copper Group: Copper, Mercury, Silver and Gold. (,8) PART I. INORGANIC CHEMISTRY. T 9 I. The Preliminary Group : Hydrogen. Oxygen. The elements of this group have but little in common. Oxygen belongs to the sulphur group, while Hydrogen, the " type-element," is a group to itself; but because of their intimate, extensive and important relations with the other elements, as well as the familiar character of their combinations with each other, we group them together as a fit beginning of the study of Chemistry. Fig. 6. HYDROGEN (H — i). — It occurs in nature occasionally un- combined, as in gas-wells and volcanoes ; but in the combined state it forms one-ninth of the water on the globe, and is the base of all acids as w T ell as a constituent of nearly all organic matter. Prepared in various ways from its compounds, e. g. 9 (a) by de- composing water with the electric current (see Fig. 14) ; (b) by displacing the hydrogen from water by means of metallic sodium " l3 12 Into a tumbler half filled with water (Fig. 6) drop a piece of sodium the size of a pea. The metal melts and dances around with a hissing noise, get- ting smaller and smaller until it disappears with a sudden snap, the spattering from which should be anticipated by covering it with a piece of card-board. 13 Repeat the above, except that the sodium is caught in a gauze spoon and 20 ESSENTIALS OF CHEMISTRY. or potassium (H 2 OH-Na^NaHO+H), or by means of other metals with the aid of heat, or (c) by displacing hydrogen from acids by means of a metal, as zinc 14 (H 2 S0 4 -f Zn=ZnS0 4 +H 2 ). Physical Properties, — A gas, transparent and colorless, and when pure, odorless and tasteless ; the lightest substance known, fourteen and a half times as light as air ; hence used for bal- loons. 15 Very diffusible ; hence hard to keep from leaking. Acts in many respects like a metal, displacing metals in chemical com- pounds, seeming to form alloys with certain metals, and a con- ductor of electricity. Hydrogen was condensed to a liquid in 1898, by Dewar. It is by far the lightest liquid known, having a specific gravity of 0.07 ; boils at — 238 C. ( — 396 F.), at ordinary atmospheric pressure, and at — 250 C. ( — 418 F.), in vacuo. Chemical Properties. — Hydrogen does not support ordinary combustion or animal respiration, but is not poisonous. It burns in air with a pale but very hot flame. With pure oxygen it forms the oxyhydrogen flame. This is the hottest flame known, and a stick of lime held in it glows with dazzling brilliancy, forming the calcium or Drummond light. Mixed with air or oxygen, it ex- plodes violently on contact with a spark. 16 pushed down beneath the mouth of a filled and inverted test-tube, allowing the gas to bubble up in the tube and displace the water. Tubefuls may then be studied, e. g., (a) Show its lightness and combustibility by turning up a tubef ul a few inches beneath a flame ; the gas rising and coming in contact with the flame, ignites with a slight explosion, (b) To show that it is com- bustible, but not a supporter of combustion, bring a lighted match to the mouth of the tube; the gas ignites and burns quietly at the open end, but the match is extinguished when passed farther up into the gas, and is relighted again as it is withdrawn. 14 Fill a side-neck test-tube one-third full of dilute (10 per cent.) sulphuric acid; add several bits of zinc; close its mouth with a cork, and attach a delivery-tube as in Fig. 7. Wait until the air is expelled, and then ignite the gas as it issues, or collect it over water, and test it as in the previous ex- periment. 15 Attach an ordinary clay pipe to the delivery-tube of the hydrogen gen- erator and blow hydrogen soap bubbles; they rise in the air. 1H Let the demonstrator fill a bladder or rubber bag with two parts of hydro- gen and one of oxygen or five of air; attach a tube and blow up soap bubbles in a basin. Touched with a flame, they explode. PART I. INORGANIC CHEMISTRY. 21 OXYGEN (O — 16).— Occurrence. Most abundant of the elements, comprising one-fifth of the air, eighth-ninths of water, one-half of the crust of the earth, and three-fourths of all organized bodies. Preparation. — Made most easily by heating potassium chlorate Fig. 8. (Fig. 8), and decomposing it into potassium chloride and oxygen, thus : KC10 3 = KC1 + 3O. 17 Physical Properties. — A colorless, odorless and tasteless gas, a little heavier (t.io times) than air. Under a pressure of 22.5 atmospheres and at a temperature of — 136 C, it condenses into 17 Grind in a mortar some potassium chlorate with half as much manganese dioxide, a black powder that facilitates the evolution of the oxygen. Heat this 10 a side-neck test-tube as in Fig. 8, or in an open test-tube. Recognize the oxygen by the energetic combustion when a match, or even the glow r ing end of the charred stick is introduced. Note. — Experiments 18, 19 and 20 are to be performed by the instructor. 22 ESSENTIALS OF CHEMISTRY. Fig. 9. Fig. 10. a colorless liquid (sp. gr. of 0.899). Water dissolves only three volumes to the hundred, but this is enough to sustain aquatic life. Chemical Properties, — Intense affinities ; combines with every element except fluorine. The product of its action is called an oxide, and the process oxidation. Oxidation so rapid as to produce heat and light is called com- bustion; if no light, slow com- bustion. Sub- stances that burn in air burn more bril- liantly in oxygen, 18 and many sub- stances that do not burn in air will burn in this gas. 19 By this property oxygen is usually recognized and dis- tinguished from most other gases. Oxygen, especially in its diluted form (air), is the great supporter of combustion, for which its abundance and universal presence eminently fit it. Combustible and supporter of com- bustion are only relative terms. When a combustible substance burns in a supporter of combustion the union is mutual, one being as much a party to the action as the other. A jet of air or oxygen burns 18 A bit of phosphorus, dried by pressing between folds of blotting paper, is placed in a combustion spoon, ignited, and lowered into a jar of oxygen. The combustion is so intense that the phosphoros volatilizes, and its vapor burns throughout the jar with a brilliancy so dazzling that it is called the " phosphorus sun." 19 A watch-spring is wound into a spiral, tipped with a bit of tinder or a piece of yarn dipped in sulphur. This is lighted and lowered into a jar of oxygen. (Fig. 9.) The iron catches fire and burns with brilliant scintilla- tions, globules of melted iron falling and melting into the glass, unless the bottom be covered with sand or water. PART I. — INORGANIC CHEMISTRY. 23 as readily in coal gas as a jet of coal gas barns in air or oxygen. 20 The one in greatest abundance is usually called the supporter of combustion. Oxidizing agents are compounds in which oxygen is held so feebly it is readily given up to substances having greater affinity for it. Uses. — The process of respiration is a species of combustion, and, as oxygen is the best supporter of combustion, it is the best (and only) supporter of animal respiration. Administered in capillary bronchitis, oedema glottidis, etc., when the patient cannot take in a volume of air sufficient to supply the requisite amount of oxygen, it has saved many lives. OZONE. — If through a portion of air or oxygen, electric sparks be passed, a part of the oxygen will acquire a pungent odor and peculiar properties. This may be observed about most electrical apparatus, especially X-ray machines, or, better still, the Siemens ozone tube. 21 The same change may be induced by various chemical pro- cesses, e. g., by mixing permanganate of potassium and sulphuric 20 Secure an ordinary lamp chimney (Fig. 10) and a wide cork to fit its lower end. Pass through the cork a narrow tube (#) connected by rubber hose with the house gas, and a wider one opening into the air. Turn on the coal gas and light it as it issues from the tube. The cork with the flame (not too large) is then inserted into the chimney, where it continues to burn, sufficient air entering through the wide tube (<:). Upon turning on more gas the air is crowded out and the chimney filled with coal gas. The gas flame disappears from the tube (#), and an air flame appears upon the tube (<:) as the entering air burns in the atmosphere of coal gas. The excess of coal gas may also be lighted as it escapes, showing a gas flame above and an air flame within the chimney. On lessening the flow of gas the air will again be in excess, and the flame again appear on the narrow tube (a). In the gas flame above the lamp chimney heat some potassium chlorate in a combustion spoon until it melts and oxygen begins to bubble up. Then lower it into the atmosphere of coal gas within the chimney. The escaping oxygen burns brilliantly, the coal gas being the supporter of the combustion. 21 Siemens' apparatus for ozoning oxygen (Fig. 11) consists of two tubes, the inner surface of the inner and the outer surface of the outer tube being coated with tin -foil, and each connected with the poles of an induction coil or Toepler-Holtz machine. A current of oxygen passing between these tubes may be ozoned to the extent of fifteen or twenty per cent. 24 ESSENTIALS OF CHEMISTRY. acid, or when phosphorus partially covered with water is exposed to the air. This modified oxygen is called ozone. It is one and Fig. ii. Fig. 12. a half times as heavy as ordinary oxygen, for its molecule contains three instead of two atoms. Very energetic, oxidizing substances unaffected by ordinary oxygen. Oxidizes potassium iodide with liberation of iodine, hence its test : paper dipped in a solution of potassium iodide and starch is colored blue in the presence of ozone." 2 Ozone is found in the air, especially after thunder storms, and when present in considerable amount (as much as .00005 per cent.) is apt to irri- tate the respiratory tract ; but by oxidizing infecting germs, etc., it prevents the spread of infectious diseases. The various preparations known as " ozon- ized ether," "ozonized water," " pyrozone," etc., are mainly solutions of hydrogen diox- ide. Into a beaker place some crystals of potassium permanganate. Suspend on a glass rod, as in Fig. 12, a strip of ozone test-paper, and beside it a strip of plain white paper for comparison. Pour from a pipette on the crystals a few drops of sulphuric acid. Cover with a card-board, and note the gradual blueing of the test paper by the ozone. PART I. INORGANIC CHEMISTRY. 25 COMPOUNDS OF HYDROGEN AND OXYGEN. — Two of these are known : Hydrogen Monoxide, H 2 0. Hydrogen Dioxide, H 2 2 . Hydrogen Monoxide or Water. — Occurrence, — Water is seen almost everywhere in nature, yet much is invisible, as in the air, Fig. 13. and hidden, as in crystals, etc. ; it constitutes the major part of all plants and animals. 23 Physical Properties, — Transparent, colorless, odorless, tasteless liquid. Below 32 F. (o° C.) it is a solid (ice), and above 212 F. (ioo° C.) a vapor (steam or vapor of water). In solidifying, 2i Melt a 5-inch piece of glass tubing into two portions, and then heat the closed ends, and blow them into slight bulbs. Into one introduce a bit of match stick and heat. Note (a) water of constitution, (£) residue, and (V) that this is destructive distillation. 26 ESSENTIALS OF CHEMISTRY. water expands ; so ice floats. The boiling-point is higher than 2i2° F. under increased pressure or when it contains solid matter in solution; and lower than 212 F. when the pressure is dimin- ished as in vacuum-pans and at high altitudes. Chemical Properties. — The chemical composition of water may be proved by {synthesis) combining its constituents (H 2 -f = H 2 0) 2i or by {analysis) passing the galvanic current through water until it is decomposed into its component gases ( H 2 = H 2 + O ) , 25 Neutral in reaction ; combines with the oxides of the metals to form hydrates (bases), and with the •oxides of the non-metals to form acids. Uses. — Water is the greatest of all solvents, and thus performs an important function in the economy of nature and human arts. It is the vehicle by which all foods and drugs must reach the tissues and the waste products leave them. Most chemicals are used in aqueous solutions, and medicines are generally adminis- tered dissolved with water. The watery solution of a fixed sub- stance is called a "liquor" and of a volatile substance an "aqua" One body is said to dissolve in another when they coalesce and their particles intimately mingle. This is possible only in the liquid and gaseous states. When a substance dissolves it takes on the physical state of the solvent, e. g., a solid or gas dissolving in water becomes a liquid and then mixes with the water, the gas ele- vating the temperature and the solid lowering it. Heat assisting the liquefaction of a solid, and opposing that of a gas, generally hastens the solution of the one and retards that of the other. Many solid substances when separating from a solution take with them, as a necessary part of the crystal, a certain definite amount of water — water of crystallization. This water does not modify the chemi- Note. — Experiments 25 and 26 had best be performed by the instructor. 2 * A mixture of two volumes of hydrogen and one of oxygen exploded in a eudiometer (Fig. 13), produces only water. 25 Fill the apparatus shown in Fig. 14 with water acidulated with sulphuric acid. Connect with a battery. The electricity passing through the water decomposes it into two volumes of hydrogen which collects in one tube and one volume of oxygen in the other. PART I. — INORGANIC CHEMISTRY. 27 cal nature of the substance, but is necessary for maintaining the crystalline form. If the crystal loses its water of crystallization by heat or exposure, it effloresces into an amorphous powder.' 6 Some substances when exposed absorb water from the air and deliquesce (melt down). Natural Waters are never pure, since water dissolves more or less of almost everything it touches ; the air through which it falls as rain, the surfaces over which it flows and the strata through which it percolates, each adding its quota to the contamination. Good, potable (drinkable) water should be cool, clear and odor- less, with just gases and solids enough in solution to give it an agreeable taste, neither flat, salty nor sweetish, and should dis- solve soap without an appreciable curd. Yet a water may be all this and be unpotable from the presence of poisonous and in- fectious contamination. Rain and snow water are the purest of natural waters, except in the neighborhood of large cities where the air is impure and the roofs dirty. Melted ice is purer than the water from which it is formed, since most of the dissolved solids remain in the unfrozen water; but the suspended matters are re- tained, many of the bacteria, especially typhoid, passing through the ordeal uninjured. Like boiled water it has a flat taste from the loss of dissolved gases. Most cities get water from rivers and lakes, while country people usually obtain theirs from springs and wells. Well water in cities, and even in small towns where the ground is more or less saturated with filth from cess-pools, drains and surface accumulations, is always more or less contaminated and dangerous, though its sparkle and agreeable taste often com- mend it to those using it. A well is often what Larrabee used to call "a perpendicular drain," and is especially dangerous if shal- low. Deep wells are such as are ioo feet or more in depth or draw their water from beneath a stratum of impervious clay or rock. These waters from contact with the earth contain min- 26 Into the other tube drop a small crystal of CuSO^H^O. Pleat gently and note [a) water condensed in cooler part of the tube and (b) the residue is amorphous. 2 8 ESSENTIALS OF CHEMISTRY. eral matters, especially salts of calcium and magnesium, making them more or less hard. The character of the mineral impurities is easily determined by their appropriate tests, and the total amount estimated by evaporating carefully (over a water-bath) a certain volume of the water and weighing the residue, which should never be over 30 or 40 grains to the gallon. But a vastly more important and dangerous contamination is organic, espe- cially nitrogenous and animal matters; not that these organic matters are themselves so dangerous, but that they form a favor- able soil, a nidus for the development and growth of various infecting germs that may be implanted therein, as during epidem- ics of cholera, dysentery and typhoid fever. Such water is a prolific source of disease, and its use is never safe. The recog- nition of the presence, number and character of these organisms is the province of the bacteriologist and requires such special care and skill, and offers so many difficulties that chemical methods are usually relied on to show the presence of the organic matter without which the germs cannot exist. The more exact methods of testing for organic contamination are so complex that they are practicable only to the chemist, but the physician may easily do it m a rough and ready way : — (a) Half fill a clean bottle with the water; warm, agitate and critically smell it ; a foul odor indicates organic impurity. (b) To 100 Cc. of the water add 1 Cc. of sulphuric acid ; warm and add a few drops of a 1 per cent, solution of potassium per- manganate ; the rose color imparted by the latter is destroyed if organic matter be present. 27 Mineral Waters are such as possess real or supposed special therapeutic value, and may be classed as follows : (a) Carbonated, those charged with carbonic acid (carbon dioxide) . 27 Various substances other than organic matter will produce the same effect, but since they are usually produced from the oxidation of nitrogenized and sulphurized organic matter they too point to previous pollution. PART I. — INORGANIC CHEMISTRY. 29 (b) Sulphur, containing some soluble sulphide, especially hydrogen sulphide. (c) Alkaline, those containing soluble alkalies such as carbon- ates or bicarbonates of sodium and potassium. (a) Lithia, such as contain salts of lithium, even when in very small amount, and associated with other substances. (e) Saline, those containing neutral salts such as the chlorides, bromides and sulphates of sodium, magnesium, etc. 28 (/) Chalybeate, which contain some compounds of iron, usually the carbonate held in solution by carbon dioxide and depositing when that gas is lost on exposure to the atmosphere. (g) Thermal or natural hot waters ; useful mainly for baths. Many waters belong to more than one class, as alkaline-carbon- ated, alkaline lithia, etc. Purification of Water. — Natural waters may be purified by (a) Boiling, which sterilizes the water by destroying the living organisms and precipitates the carbonates of calcium, magnesium and iron by driving off the carbon dioxide holding them in solu- tion. (b) Filtration, that is, passing it through some clean, insoluble, porous substance as paper, charcoal, sand, brick, stone or un- glazed earthenware. Some filters, if well made and clean, will remove not only the suspended matters, but a considerable por- tion of the dissolved organic substances. Filters of unglazed porcelain are sold which remove all micro-organisms and yield a water perfectly sterile. Many cities now have their water sup- plies filtered through clean, sharp sand; and experiments have shown that " A sand filter 5 feet thick and filtering two million gallons per acre a day will remove 99.98 per cent, of the bac- teria," and that the most polluted waters can thus be rendered almost harmless. (c) Distillation in which the water is boiled and its vapor 2K Sea water is a saline water containing about 3J& P er cent, of mineral matter, mainly sodium chloride, with smaller quantities of other mineral salts. 3° ESSENTIALS OF CHEMISTRY. passed through a block-tin or glass condenser as shown in Fig. 15, and recondensed and gathered in a clean vessel. 29 Where Fig. 15. great purity, is required as in the preparation of the officinal dis- tilled water (aqua destillata U. S. P.), the first 10 per cent, is rejected as liable to contain the gaseous impurities, and the last 10 per cent, left in the boiler, lest some of the more volatilizable solids come over with it. so Hydrogen Dioxide. — Peroxide of Hydrogen (H 2 2 ) . Prepared most easily by passing C0 2 through barium dioxide in suspended in water, thus : BaO a +CO a +H a O=BaC0 3 +H 2 O a , or commercially by hydrofluoric acid thus : Ba0 2 + 2 HF-BaF 2 + H 2 2 . yy Dissolve 1 Gm. of CuSO in water and boil in a stoppered side-neck test- tube (Fig. 16) introducing the delivery tube into a clean test-tube set in a beaker of crushed ice. Note the absence of taste, color, etc., in the distillate. x0 If a solid be so treated the process is called sublimation instead of distil- lation; and the product is a sublimate instead of a distillate. When a mixture of two or more liquids is distilled, the one having the lowest boiling point comes over first, leaving the others behind; and the process is called frac- tional distillation, but the separation is seldom complete. PART I. INORGANIC CHEMISTRY. 3 1 The insoluble barium salt may be allowed to subside, and the clear aqueous solution of H 2 2 poured off. It is sold in various strengths, according to the number of volumes of oxygen a certain volume of the solution will yield, the ten-volume solution being most employed. The so-called u Ozonized ether " is made by shaking this solution with ether, which extracts the hydrogen dioxide. Properties. — When concentrated, hydrogen dioxide is a color- less, syrupy liquid of pungent odor and taste, and decomposes so easily into H 2 + that it must be kept in a cool place, well bottled, in acid solution, away from contact with organic matter, and agitated as little as possible. Uses. — Being an active oxidizer, 81 it is a valuable bleaching agent, 33 especially for woolen fabrics, and is largely sold as blondine for bleaching the hair. As it destroys bacteria and dis- solves pus, etc., it is used very abundantly in medicine and surgery to cleanse ulcers and abscesses, and to dissolve the membranes of scarlet fever, diphtheria, etc. As it effervesces with pus, 34 it is used as a test for pus in the urine. RADICALS. — Every molecule is composed of two parts, called radicals, held together by chemical affinity. Both radicals may be elements, as in H — CI, or one may be elementary and the other compound, as H — N0 3 , or both compound, as NH 4 — N0 3 . Some compound radicals can be isolated, e. g n by heat: Hg — CN = Hg+CN. Others decom- pose whenever set free. 31 Take a little hydrogen dioxide solution, add a drop each of potassium chromate and sulphuric acid and a little ether, and shake; the potassium chromate is oxidized with the production of blue perchromic acid. 32 Secure an old painting darkened with age, or an old engraving yellowed and soiled; wash it with hydrogen dioxide, and note the brightening effect. 33 Dip a strip of ozone test paper into a solution of hydrogen dioxide, and note that it is not blued until a few drops of ferrous sulphate is added to act as an oxygen carrier. 34 Add hydrogen peroxide to milk in test-tube and note effervescence, the cells in the milk acting as would pus corpuscles. 32 ESSENTIALS OF CHEMISTRY. Often when a galvanic current is passed through a com- pound, the chemical affinity is overcome by the electricity, and the molecule separates into its two radicals, one of which goes to the positive and the other to the negative pole. 35 Unlike electrical conditions attract, so the radical going to the negative pole must be electro-positive, and the one going to the positive pole electro-negative. The metallic radicals are relatively electro-positive and the non-metallic electro-negative. Some radicals are more intensely electro-negative or electro-positive than others. In the following list the more common elements are so arranged that each is usually posi- tive to those following it and negative to those preceding : Positive end : -f K, Na, Mg, Zn, Fe, Al, Pb, Sn, Bi, Cu, Ag, Hg, Pt, Au, H, Sb, As, C, P, S, N, I, Br, CI, F, O.— Negative end. A radical is electro-positive or electro negative only in its relation to other radicals ; for while C is positive to O, it is negative to K. In formulas the electro-positive radical is written first and the electro-negative next. The greater the difference between the electrical condi- tion of two radicals, the greater the energy with which they unite and the more stable the product, and vice versa; e.g., O has a strong affinity for K, a weak one for*Cl, and will not unite with F under any circumstances. An idea once prevailed that the relation of affinities were fixed and con- stant between the same substances, and great pains were taken to construct tables similar to the above to show what 35 Into a jar put some water; add solutions of red litmus, potassium iodide, and boiled starch ; connect with the galvanic battery. The electric current decomposes the potassium iodide into iodine, which gathers at the positive pole, producing a blue color, with the starch, and potassium at the negative, where it produces alkali, turning the red jitmus blue. PART I. — INORGANIC CHEMISTRY. 33 was called the " precedence of chemical affinities." These tables showed the order of affinities for the circumstances under which the experiments were made, and nothing else. The circumstances attending chemical reactions are so complicated that in many cases it is impossible to predict the precedence of affinities and the result of an untried experiment. Among these modifying causes may be mentioned : 1. Temperature, changes of which often reverse chemical affinities. Moderately heated, mercury and oxygen will readily combine, but when highly heated their affinity is destroyed, and they will refuse to unite, or, if already com- bined, will separate. Ordinarily free carbon has no affinity for oxygen, but at high temperatures it surpasses most other elements in its greediness for that substance, even taking it from a metal so extremely electro-positive as potassium. 2. Volatility. — Whenever in a mixture of two or more sub- stances it is possible, by a re-arrangement of the radicals, to form a compound volatile at the temperature of the experiment, such re- arrangement will occur and the volatile compound be formed. For example : FeS+H 2 SCV=FeS0 4 +H 2 S ; or, 2NH 4 Cl-f CaC0 3 =(NH 4 ) 2 C0 3 +CaCl 2 ; or, H 3 B0 3 +3NaCl=3HCi+Na 3 B0 3 . 3. Insolubility. — Whenever, on mixing two or more substances in solution, it is possible, by re-arrangement of the radicals, to form an insoluble compound, that re-arrangement will occur and the insoluble compound be formed as a precipitate. For example: CaCl 2 +(NH 4 ) 2 CO s =CaC0 3 +2NH 4 Cl. It is especially important to remember this principle, for its application in tests, incompatibilities, and antidotes. 4. Nascent State. — Ordinarily the atoms of an element are 34 ESSENTIALS OF CHEMISTRY. grouped in pairs, and hence somewhat indifferent to the attractions of other atoms ; but just as they are being liber- ated (born) from a compound they are alone, and each atom, having no fellow, readily enters into combination with any atom it meets. This state is called nascent (nasci, to be born). 5. Catalysis, — This is the name given to the unexplained influence exerted by some substances of inducing chemical reactions between other substances without themselves undergoing any change. The VALENCE of a radical is its combining value, or its value in exchange for other radicals. Stt Here again hydro- gen is taken as the standard. A radical that combines with or takes the place of one atom of hydrogen is said to be univalent (one valued); of two atoms, bivalent; three, triva- lent ; four, quadrivalent ; five, quinquivalent ; six, sexivalent. The valence is indicated by a Roman numeral just above and after the radical, thus: (NHJ 1 , Ca 11 , (P0 4 ) m , Si IV , As v , S VI . The two radicals of every saturated compound must possess an equal number of valences. Hence, In HC1 the radical CI is equivalent to 1 atom of hydrogen; In H 2 the radical O is equivalent to 2 atoms of hydrogen; In NH 3 the radical N is equivalent to 3 atoms of hydrogen; In CH 4 the radical C is equivalent to 4 atoms of hydrogen. Therefore CI is univalent, O bivalent, r trivalent, and C quadrivalent. The same regard for valence is observed when radicals are made to displace each other, thus: H (S0 4 ) n requires two atoms of K 1 or one of Zn 11 to form K^SOJ 11 or Zn n (S0 4 ) n . Some elements exercise more than one valence : e. g., mercury may be univalent, as in Hgl, or bivalent, as in 36 The student should bear in mind that valence has nothing to do with the combining weight or the chemical activity of an element. PART I. INORGANIC CHEMISTRY. 35 Hgl 2 ; or iron may be bivalent, as in FeCl 2 , or trivalent, as in FeCl 3 . The termination " -ous" is given to those compounds in which the positive element exercises its lower- valence, and " -iV" to those in which the higher valence is exercised, as FeCl 2 , ferrous chloride ; and FeCl 3 , ferric chloride. In the following table the most commonly occurring simple or elementary radicals are arranged according to their valences : Table of Valence. I. II. III. IV. V VI. F, CI . . Ba, Sr . . Al . . . . C, Si . . Br, I . . Ca, Mg - Au . . • Pt • . . . H, Ag, . . Cd,Zn . . O • • . . Bo . . - . K, Na, ■ • Pb, Sn . . Pb, Sn . .. 1 . . (NH 4 ), Li, S,Se. . Fe, Cr . . Mn, Co . Ni . • . • Fe, Cr . . Mn, Co . Ni ••• N, P .' N, P. S,Se. . . Bi, Sb, As. Bi, Sb, As. . . Cu.Hg. • Cu, Hg . The next table shows the valences, together with the symbols and formulae, of the most common electro-negative (acidulous) radicals: CI is the negative radical of all chlorides. Br is the negative radical of all bromides. I is the negative radical of all iodides. CN is the negative radical of all cyanides. HO is the negative radical of all hydrates. NOo is the negative radical of all nitrates. C10 3 is the negative radical of all chlorates. [ C 2 H 3 2 is the negative radical of all acetates (Ac.) M 1 3 6 ESSENTIALS OF CHEMISTRY. O is the negative radical of all oxides. S is the negative, radical of all sulphides. S0 3 is the negative radical of all sulphites. * j S0 4 is the negative radical of all sulphates. C0 3 is the negative radical of all carbonates. C 2 4 is the negative radical of all oxalates (Ox.). C 4 H 4 6 is the negative radical of all tartrates (T.). %* f C 6 H 5 7 is the negative radical of all citrates (Cit). f-% \ P0 4 is the negative radical of all phosphates. Hf2 [ B 3 * s the ne S auve radical of all borates. FORMUL/E — In constructing formulas, (a) write the positive radical first and the negative second, thus: Ea CI; and (b) make their valences balance, thus: Ba Cl 2 ; for in every saturated compound each radical must possess the same number of valences. NOMENCLATURE — In naming a formula, give the simple name of the positive radical first, and then the name of the negative radical with the termination " -ide," if the nega- tive radical be an element, thus: Na 1 CI 1 Ca 11 Br x 2 Sodium Chlor-ide; Calcium Brom-ide ; A\ m 2 O 3 Pt IV I 4 Aluminum Ox-ide ; Platinum \od-ide. But if the negative be a compound radical, i.e., one in which another element, as oxygen, is associated with the leading negative element, the termination is " -tie " or " -ate" according to whether the negative element exercises its lower or higher valence, taking less or more oxygen, for example: NaCl0 2 NaC10 3 Sodium Chlor-tfte; Sodium Chlor- ate ; If the negative element exercises a still lower or a still higher valence, and takes still less or still more oxygen? the prefix " hypo- " is used for the lowest and prefix i( per- " for the highest, thus ; PART I. — INORGANIC CHEMISTRY. 37 Na CIO ; Na C10 2 Sodium 7iypo violet, I, 127 The members of this group are all univalent and much alike in Fig. 16. m their sources and physical and chemical properties. They differ in degree rather than in kind, forming a graded series. Hence we will consider them all together. 38 ESSENTIALS OF CHEMISTRY. Sources. — Never free in nature. The principal source of fluor- ine is fluor spar (CaF 2 ), while compounds of chlorine, bromine and iodine occur in sea and other salt waters. Preparation. — Free fluorine is obtained only with great diffi- culty ; the others may be prepared by removing the hydrogen from their hydrogen salts (hydracids) by means of oxygen derived from manganese dioxide, 37 thus : — 4HCI + Mn0 2 = MnCl 2 + 2H 2 + Cl 2 . 4HBr + Mn0 2 = MnBr 2 -f 2H 2 -f Br 2 . 4HI + MnO a == Mnl 2 +2H 2 + I 2 . 38 Physical Properties. — Fluorine is a nearly colorless gas, with properties resembling chlorine, but more intense. Chlorine is a very irritating yellowish-green gas, two and a half times as heavy as air, slightly soluble in water (three volumes), forming "Aqua chlori, U. S. P." Bromine is a red liquid, giving off red vapors of a disagreeable, irritating odor; very slightly soluble in water. Iodine is a solid, in bluish-gray scales, which, when warmed, give off violet vapors ; practically insoluble in water except by the intervention of an alkaline iodide ; 42 soluble in alcohol ; irritating, even caustic. Chemical Properties. — Intensely electro-negative ; great affinity for the metals, 40 especially hydrogen. 41 In negativeness, and con- Experiments 40 and 41 had best be performed by the instructor. 37 Into a flask standing in a dish of water warmed over a heater and the whole apparatus (Fig. 16) under a hood, pour several ounces of HC1 and half as much Mn0 2 in lumps, and agitate. The gas passes out, and being heavier than air, collects in the bottle, where its yellowish green color makes it visible. 38 To each of three small test-tubes add a few grains of manganese dioxide. To the first add a few crystals of Na CI, to the second, of K Br, and to the third, of K I. Add a few drops of strong H. 2 S0 4 and warm. Note the evolution of CI from the first, Br from the second, and I from the third, and study the prop- erties of each, taking care not to inhale them, and stopping the reaction as soon as the test is finished. * 9 To a little chlorinated lime (bleaching powder) in a test-tube, add some dilute acid and note the evolution of CI. 40 Into a jar of chlorine introduce some copper or bronze foil, or sprinkle some powdered antimony. They inflame spontaneously. 41 (a) Into a jar of chlorine lower a lighted candle. The hydrogen of the PART I. INORGANIC CHEMISTRY. 39 sequently in affinity for the metals, F is greatest, CI next, Br next, and I least. Therefore, in compounds with the metals, F will displace CI, and CI will displace Br, and either F, CI, or Br will displace I. 42 These elements destroy coloring matters and noxi- ous effluvia in two ways : (i) by abstracting their hydrogen; (2) by abstracting the hydrogen of water, setting free nascent oxygen, which oxidizes the matters in question. 43 Medical. — Chlorine gas and bromine vapor are used for disin- fection. Inhaled they cause severe coryza and bronchitis. Taken into the stomach, bromine and iodine cause gastro-enteritis. The antidote is boiled starch. Locally bromine is used as an escha- rotic and iodine as a counter-irritant. Pharmaceutical. — The following preparations are officinal : Tinctura Iodi (7 per cent.) ; and Liquor Jodi Compositus (Lugol's Solution) (Iodine 5, potassium iodide to, and water 100). The so-called colorless tincture of iodine is made by adding ammonia- water to the tincture until it is decolorized by converting the iodine into ammonium iodide. 44 tallow burns in the chlorine to form hydrochloric acid, and all the carbon is liberated as smoke. {&) Into a similar jar thrust a piece of paper dipped in warm turpentine. It inflames spontaneously and burns, evolving dense clouds of smoke. 42 Take two large test-tubes half full of water. Into one put a grain of po- tassium bromide, into the other potassium iodide; add chlorine-water to each. The chlorine will liberate the bromine in one and the iodine in the other. This may be shown (a) by their color; (&) by adding a few drops of carbon bisul- phide or chloroform, which on agitation will gather all the free bromine and iodine, and be colored brown with the one and violet with the other; or (c) by adding a few drops of starch -water, which will give brown with bromine and a deep blue with iodine. 43 (a) Into one bottle of chlorine gas introduce a piece of dry calico, into another a moist piece. The moist calico is rapidly bleached, while the dry is but slowly affected. (£) To a solution of indigo, cochineal, or some aniline color, add chlorine water. It is immediately decolorized. 44 Put a crystal of iodine in each of three small test-tubes, to the first add some water, to the second, alcohol, and to the third, a solution of potassium iodide; note it is very slightly soluble in water but readily so in alcohol and in a solution of potassium iodide. Put a drop of the alcohol solution (tincture) on the hand and note the brown stain. To each of the test-tubes add a few drops of ammonia water or liquor potassae and note the disappearance of the brown color. 40 ESSENTIALS OF CHEMISTRY. Tests. — In the free state chlorine and bromine may be known by their bleaching, color, odor, etc. Iodine is recognized by the blue color it strikes with starch. ACIDS. — Just as in the world at large, the balancing of forces is due to a general struggle between opposite and antagonistic qualities, as between light and darkness, heat and cold; so the chemical status seems to be a resultant of the antagonism of the opposing " positive " and " negative " within the molecule. If the positive radical predominates over the negative, this excess of positiveness gives the com- pound an alkaline character ; while on the other hand a predominance of the negative over the positive gives it an acid character. Thus an excess of negativeness or of positiveness finds expression in the compound as acidity 45 or alkalinity. 46 Since H is the weakest of all positive radicals, it is over it that strong negative radicals predominate most completely ; so that the hydrogen salts are as a class the most acid 47 in all chemistry, in fact they are called the acids. Acids may be divided into two classes: (a) Hydracids which are the " -ide " salts of hydrogen, the negative radicals consisting only of a single element. (J>) Oxacids in which the negative element has oxygen associated with it, forming a compound negative radical. The acids are given a somewhat special nomenclature, the main portion of which is derived from the name of the 45 Acid substances may be recognized by their usually having a sour taste, by redding certain vegetable coloring matters, such as litmus, and by neutralizing alkalies. 46 Alkaline substances generally have a soapy taste and neutralize acids, and restore to the original color vegetable matters reddened by acids. 47 Hydrogen hydrate (HHO) or water is one salt of hydrogen that is not acid. The radical HO being as weakly negative as H is weakly Dosltive, neither predominates, and water is neutral. PART I. INORGANIC CHEMISTRY. 4 1 negative element. Hydracids are given the prefix " hydro- " and the termination "-ic." The oxacids conform to the regular nomenclature except that the word "acid " is used instead of the name of the positive radical, hydrogen, and the terminations "-ate" and " -ite " become " -ic " and "-ous" respectively. These rules are illustrated in the little table of chlorine acids given below. The oxacids are generally considered as formed by the combination of water with the oxides of the negative element, the different oxides being distinguished by prefixes' derived from the Greek numerals indicating the number of oxygen atoms, thus: CI 2 0— Chlorine Monoxide. C1 2 2 (?)— Chlorine Dioxide. C1 2 3 — Chlorine Trioxide. C1 2 4 — Chlorine Tetroxide. 2 5 — Chlorine Pentoxide. C1 2 7 — Chlorine Heptoxide. The following table illustrates the formation and nomen- clature of the chlorine acids: Cl a O+H 2 0— 2HCIG — Hydrogen Hypochlorite— Hypochlorous acid. Cl 2 3 -r-H 2 0=2HC10 2 — Hydrogen Chlorite— Chlorous acid. Cl 2 5 -hH 2 0— 2HOO a — Hydrogen Chlorate— Chloric acid. Cl 2 7 -f H 2 0=2HC10 4 — Hydrogen Perchlorate— Perchloric acid. The Hydracids of the chlorine group are as follows : — H + F = II F — Hydrogen Fluoride — Hydrofluoric acid. H + CI = HC1 — Hydrogen Chloride — Hydrochloric (muriatic) acid. H-f Br — HBr — Hydrogen Bromide — Hydrobromic acid. H -j- I — HI — Hydrogen Iodide — Hydriodic acid. Prepared by treating the appropriate salt with H 2 S0 4 , thus : — CaF, + H 2 S0 4 = CaS0 4 + 2HF. 2NaCl + H~S0 4 = Na 2 S0 4 + 2HCI.* 8 2KBr + H 2 S0 4 = K 2 S0 4 + 2HBr. 2KI + H 2 S0 4 = K 2 S0 4 + 2HI. 48 To prepare hydrochloric acid gas, put several ounces of common salt and 4 42 ESSENTIALS OF CHEMISTRY. Physical Properties. — Colorless, irritating gases; sharp, sour taste ; 49 very soluble, water dissolving several hundred times its own volume, forming aquae known by the simple name of the acid itself, thus : The officinal " hydrochloric acid " is a solution of the hydrochloric acid gas in water. Fig. 17. Chemical Properties. — Strong acids ; true acids even without water. Uses. — HF attacks silica energetically, hence is used to etch glass ; very poisonous, and burns made by it heal with difficulty. about twice as much sulphuric acid into a flask, and warm. The gas comes off in abundance and may be collected in a dry bottle (like chlorine, Fig. 16), or over mercury. The solution of the gas (the ordinary form) is obtained by passing the gas through a series of Wolff bottles containing cold water and arranged as shown in Fig. 17. For making HBr or III, phosphoric acid is better, since sulphuric is apt to be partially reduced with evolution of S0 2 . 49 Fill a large dry glass tube with HC1 gas and quickly invert it in a dish of water colored blue with litmus. Note that the gas is instantly dissolved and that the water rushes up to take its place and the litmus is reddened by the acid. Let some of the gas pour into the mouth and note sour taste. PART I. — INORGANIC CHEMISTRY. 43 HCl is very useful in the arts. Aqua regia, or nitro-muriatic acid, is a mixture of nitric and hydrochloric acids. It is the best solvent of gold 50 and platinum. The metals are attacked by the nascent chlorine which is evolved when the H of the HCl is oxidized by the O of the HNO a . In medicine HCl is often prescribed as a tonic. HBr, like all bromides, is a sedative. HI, like all iodides, is an alterative. Tests.— Fluoride - H 2 S0 4 — etches glass. 51 - 52 Chloride -fAgN0 3 — white precipitate, soluble in ammonia. Bromide + AgNO a — yellowish-white precipitate, slightly soluble in ammonia. Iodide + AgN0 3 — yellow precipitate, insoluble in ammonia. 53 If to a bromide or iodide some chlorine-water and starch paste be added, the bromine and iodine will be liberated, the bromine striking a brown and the iodine a blue color with the starch. Oxysai.ts of the Chlorine Group. — The members of the chlorine group are so electro-negative that they have but little affinity for oxygen, it being also strongly electro-negative. Bromine has for 50 Take two beakers and put into one 5 Cc. of HCl and into the other 2 Cc. of HNO3. Add to each a sheet of gold-leaf. Note that the gold-leaf is un- affected. Now pour the contents of one beaker into the other and note that the gold-leaf is dissolved in the mixed acids (aqua regia). 51 On a plate of glass coated with wax or copper- plate varnish (six parts of mastic, one of asphalt, and one of wax dissolved in turpentine) draw a design with a pointed instrument. Invert over a lead dish containing pow T dered CaF. 2 moistened with strong H 2 S0 4 and warm gently. Hydrofluoric acid gas is evolved and attacks the glass wherever the wax has been scratched off. Upon removing the wax the design is found permanently etched on the glass. 52 To a small lead dish about the size of a watch crystal, such as any tinner can stamp out of sheet lead, add 5 grains of CaF. 2 and moisten with strong H 2 S0 4 . Cover this with a watch crystal coated with melted paraffin and on which the student has drawn a design with a needle or fine pencil point, and warm gently. Leave during lecture hour and note the etching. 53 Take three small test-tubes and add a few drops of a solution of a chloride to the first, of a bromide to the second, and of an iodide to the third. Add to each 5 drops of AgNQ, solution. Note a pure white precipitate of AgCl in the first, a yellowish white of AgBr in the second, and a yellow of Agl in the third. Add ammonia water to each and note that the AgCl dissolves easily, the AgBr with difficulty, and the Agl remains insoluble. 44 ESSENTIALS OF CHEMISTRY. it less affinity than iodine, chlorine less than bromine, and fluorine so little that it never combines with oxygen at all. Hence the oxysalts of the group are very unstable substances, decomposing easily, and readily giving up their oxygen. So they are much used in chemistry as oxidizing agents, 54 in medicine as disin- fectants, and in the combustible and explosive mixtures of pyro- techny, etc. 55 III. Sulphur Group. Oxygen (already described) O • 16 Sulphur S 32 Selenium Se 79 Tellurium Te 128 The elements comprising this group are solid at ordinary tem- peratures ; bivalent and sexivalent ;. possess electro-negative affinities which, as in most other groups, decrease as the atomic weights increase ; form hydracids as well as oxacids. The analogy between their compounds is shown in the follow- ing table : Hydro-ic Hypo-ous Acid. Dioxide. Trioxide. Acid. -ous Acid. -ic Acid. H 2 S so, so 3 H 2 S0 2 H 2 S0 3 H 2 S0 4 . H 2 Se Se0. 2 Se0 3 H 2 Se0 3 H 2 Se0 4 . H 2 Te Te0 2 Te0 3 H 2 Te0 3 H 2 Te0 4 Selenium and Tellurium are of no medical interest, and will not be noticed further. 5 * Their oxidizing action on combustibles maybe shown by: (a) Mix to- gether a drachm each of powdered potassium chlorate and sugar; place on a brick, and touch off with a glass rod dipped in sulphuric acid. A vigorous combustion occurs, (b) Drop some crystals of potassium chlorate into a con- ical glass of water; add several bits of phosphorus; then by means of a pipette introduce sulphuric acid at the bottom of the glass. The phosphorus takes fire and burns at the expense of the oxygen of the potassium chlorate. 55 Mix on a sheet of paper 2 grams of powdered potassium chlorate and .5 gram of some combustible powder, as sulphur, antimony sulphide, oj tannin. Wrap it up in the paper, place upon an anvil, and strike with ahammer. It explodes violently. PART I. INORGANIC CHEMISTRY. 45 SULPHUR occurs free, especially in the neighborhood of vol- canoes ; occurs combined as sulphides and sulphates in many valuable ores, and in small quantity in the animal and vegetable kingdoms. Preparation, — The native sulphur, freed from stones, is refined by distillation, as shown in Fig. 18. The crude sulphur is melted in the tank by the hot draft from the fire below, and then runs down through a pipe into the retort, where it is vaporized. This Fig. 18. vapor, entering a large brick chamber, is condensed into fine, feathery crystals, called flowers of sulphur or sublimed sulphur. If the chamber be hot, it condenses into a liquid, which is drawn off and moulded into rolls, called roll brimstone. Sublimed sul- phur is apt to contain more or less acid, and is washed (sulphur lotum). Boiled with lime and precipitated with HC1, it forms sulphur precipitatum, U. S. P. This mixed with water is milk of sulphur (lac sulphuris, U. S. P.). 46 ESSENTIALS OF CHEMISTRY. Physical Properties, A brittle yellow solid ; insoluble in water, hence tasteless; almost insoluble in alcohol, but very soluble in benzine, chloroform and carbon disulphide. It occurs in four allotropic modifications. 56 Chemical Properties. — Inflammable, hence called "brimstone" (burn-stone). Combines with metals, 57 forming sulphides. 58 Sul- phur forms compounds remarkably analogous to those of oxygen, '. £••• — H 2 , . .KHO C0 2 H 2 C0 3 HCNO. H 2 S KHS CS 2 H 2 CS 3 HCNS. Uses. — In the arts, to make gunpowder, matches, etc. ; in med- icine, as a laxative, parasiticide and alterative. We have only theoretical explanations of the method of its absorption ; but that it is absorbed is certain, for persons taking it excrete enough to blacken silver carried on the person. Hydrogen Sulphide — H 2 S — Hydro sulphuric Acid or Sulphur- etted Hydrogen — occurs in sewer gas and other effluvia from de- composing organic sulphurized matters, and in the water of sul- phur springs. Prepared in laboratory by decomposing a sulphide, 59 thus : — FeS -f H 2 S0 4 = FeS0 4 + H 2 S. 56 Melt a tablespoonful of sulphur in a covered porcelain dish or crucible; let it cool and break the crust that forms and pour the still melted sulphur into water. Note (a) the prisms remaining in the dish as well as (b) the plastic amorpkoussulphm in the water. Dissolve a pinch of sulphur in a few drops of CS 2 ; allow a drop to evaporate on a slide and examine (c) the rhombic crys- tals under the microscope. Boil a little lime and sulphur in water; decant the clear liquid and add HC1. Note the (d) amorphous white powder of precipi- tated sulphur suspended in the liquid (milk of sulphur). 57 In a small glass flask, a little sulphur is heated to boiling. If now a bun- dle of fine copper wire or a piece of sodium, in a combustion spoon, be previ- ously heated and then lowered into the vapor, it burns brilliantly. 58 Mix in a dish equal parts of iron filings and flowers of sulphur.: moisten with water and set aside. Within a half hour it gets hot, vaporizes the water, and is converted into a black mass of FeS. 59 Into a side-neck test-tube, or better a flask with funnel and delivery tube, Fig. 19, put a few lumps of FeS and dilute H 2 S0 4 or HC1 enough to cover the FeS. Note the physical and chemical properties of the gas evolved. PART I. INORGANIC CHEMISTRY. 47 Physical Properties. — Colorless gas, having the odor of rotten eggs or intestinal flatus ; slightly soluble in water. Chemical Properties, — Very feeble acid : burns 60 with pale blue flame : — H 2 S + 30 = S0 2 + H 2 0. Forms characteristic precipitates with most metallic salts, 61 hence a valuable test reagent. Fig. 19. Tests. — The presence of H 2 S even in minute quantities may be *" ;0 Burn the gas from a jet : (a) Hold near the flame a glass rod dipped in ammonia; white crystals of ammonium sulphite are formed, (b) Hold a cold, dry bell-glass over the flame; it is bedewed with water. 61 To show the action of H 2 S on metallic salts, connect several wash bottles with the generator as shown in Fig. 20. A dilute solution of lead acetate is put in the first, of tartar emetic (antimony) in the second, of arsenic in the third, of zinc sulphate in the fourth. The gas in passing precipitates lead sul- phide (black) in the first, antimonicus sulphide (orange) in the second, arsen- ous sulphide (yellow) in the third, zinc sulphide (white) in the fourth. 4« ESSENTIALS OF CHEMISTRY. detected by its odor, and by its blackening paper moistened with a solution of lead acetate. Fig. 20. Physiological. — When inhaled, H 2 S is an active poison, combin- ing with the hsemgalobulin and destroying its oxygen-carrying power. Even when highly diluted, as in the atmosphere of city dwellings, clumsily "fitted with the modern conveniences," it pro- duces a low febrile condition. When concentrated, or even mod- erately diluted (one per cent, and over), the gas proves rapidly fatal. Treatment. — Fresh air, artificial respiration, and stimulation. Carbon Bisulphide — CS 2 . — Obtained by bringing S into con- tact with heated charcoal. A colorless, volatile liquid of a fetid odor, unless it is very pure. A valuable solvent for S, P, india- rubber, etc. Dissolved in water (1-400) a useful antiseptic. Sulphur Oxides and Acids. Dioxide — S0 2 +H 2 0==H 2 S0 3 — Sulphurous acid. Trioxide — S0 3 -|-H 2 0— H 2 S0 4 — Sulphuric acid. PART I. INORGANIC CHEMISTRY. 49 Sulphur Dioxide, S0 2 , occurs whenever sulphur or any of its compounds are burned in air or oxygen. Prepared in laboratory by decomposing and reducing sulphuric acid by copper or charcoal, 62 thus : 2H 2 S0 4 +Cu=CuS0 4 +2H. 2 0+S0 2 . 2H 2 S0 4 + C =2S0 2 +C0 2 +2H 2 0. Physical Properties, — A colorless gas, with a suffocating odor (of burning matches) ; dissolves in water to form sulphurous acid (H 2 S0 3 ). Chemical Properties. — Neither burns nor supports combustion; a strong deoxidizer ; by removing O from coloring matters and infecting germs it bleaches 63 and disinfects. Uses.— Sulphur dioxide, sulphurous acid, and the sulphites possess the property of destroying microorganisms and arresting fermentations. A sulphite digested with sulphur forms a so-called hyposulphite, thus : Na,S0 3 +S-=Na 2 S 2 3 . Sodium hyposulphite, more correctly called sodium thiosul- phate, has the same uses as the sulphites, and is also a valuable solvent of the silver salts in photography. Sulphur Trioxide, S0 3 . — Made by oxidizing S0 2 in the manu- facture of sulphuric acid. This is done upon a large scale by passing S0 2 from burning sulphur into a chamber kept filled with 62 To make S0. 2 and study its properties: (a) burn a sulphur match; (b) warm a mixture of powdered S and H.,S0 4 ; (c) heat copper wire in strong H. 2 S0 4 ; (d) add HC1 to sodium sulphite. Note that the gas is colorless and irrespirable, neither burns nor supports combustion, dissolves in water, form- ing an acid solution (H 2 S0 3 ) that tastes sour and bleaches organic colors. 63 Some sulphur is ignited beneath a tripod on which fresh flowers are placed, and the whole covered by a bell-glass. The flowers are bleached. The color may be restored by washing with some dilute alkali or acid that will combine with or displace the S0 2 , or with very dilute nitric acid, which will restore the oxygen removed by the S0 2 . 50 ESSENTIALS OF CHEMISTRY. vapor of nitric acid, steam and air. 64 The nitric acid gives up a part of its oxygen to oxidize a portion of the S0 2 to S0 3 . 2HN0» + 3S0 2 1=± 3SO3 + II 2 + N 2 2 . The S0 3 then combines with the water thus produced (S0 8 + H 2 0==H 2 S0 4 ), and more water is supplied by a jet of steam thrown constantly into the chamber. The N 2 2 has the power of taking up oxygen from the air and becoming N 2 4 , N 2 2 + 2 = N 2 4 , which in turn parts with this oxygen to oxidize a new quantity of S0 2 , N 2 4 + 2S0 2 = N 2 2 + 2SO a . Thus the process is kept up as long as the S0 2 , air, steam, and N 2 2 are supplied. The acid condenses with the water upon the floor of the chamber, and is drawn off, concentrated, and sold as Sulphuric Acid— H 2 SQ — " Oil of Vitriol." 65 Physical Properties. — A dense, colorless, oily-looking liquid, without odor. 66 Chemical Properties. — Strong acid ; very avid of water, not only dissolving in it, but combining with it, the act evolving con- siderable heat ; 67 chars organic matters by abstracting H and O to form water. 68 61 The manufacture of sulphuric acid may be illustrated on the lecture table by the apparatus shown in Fig. 21. The lead chamber is represented by a large flask. Into this are led (a) N 2 2 from the flask on the right; (b) S0 2 from a mixture of sulphur and manganese dioxide in the flask in the rear; (c) steam from the other flask, and (d) air or oxygen through the open tubes. 65 To make H 2 S0 4 in small test-tubes, (a) Boil a little powdered sulphur and strong HN0 8 ; (£) carefully heat a pinch of sulphur with a few crystals of KC10 ;H till it ignites; test for H 2 S0 4 by means of BaCl 2 solution. 66 Take a reagent bottle of strong H 2 S0 4 and note its appearance, weight, taste, etc. 67 To about 5 Cc. of it in a test-tube add an equal bulk of water and note heat produced. 6S Moisten a bit of match, paper, cloth or other organic substance, with the acid and note that it is charred, even the dilute acid doing so if it is warmed; and for this reason be careful not to spill any on the table or your clothes. PART I. INORGANIC CHEMISTRY. Si Tests. — (i) The concentrated acid, if placed on a piece of paper or other organic material, will char it. fi9 If dilute, it will char the paper only after being warmed and concentrated by the Fig. 21. evaporation of its water. (2) Sulphuric acid, or any other sul- phate, will form with a solution of a barium salt a white precipi- tate (BaS0 4 ) insoluble in nitric or hydrochloric acid. 70 Uses. — So important in the arts that the commercial prosperity of a country may be measured by the amount of H. 2 S0 4 con- sumed. Properly diluted, it is a refrigerant tonic, but concen trated it is a severe caustic. 69 Pour some strong H.,S0 4 on an equal quantity of sugar or strong syrup ; note that a mass of charcoal is formed. 10 To 5 Cc. of water in a test-tube add a few drops of some sulphate and then a few drops of BaCl 2 . Note white precipitate. Agitate and pour half into another tube. Add HC1 to the 6rst tube and HN0 3 to second, and note that the precipitate (BaS0 4 ) is not dissolved. 52 ESSENTIALS OF CHEMISTRY. IV. Nitrogen Group. Nitrogen, N 14 Phosphorus, P 31 Arsenic, As 75 Antimony (Stibium), Sb 120 Bismuth, . Bi 208 Trivalent and Quinquivalent. This group, as shown below, forms a graded series from nitrogen at the negative, to bismuth at the positive end : — N P As Sb < Bi 14 31 75 120 208 Sp. gr. 1.83. Sp. gr. 5.67. Sp. gr. 6.7. Sp. gr. 9.8. Gas, with full A soft solid. Solid. Dense solid. Very dense solid, negative ten- dencies. Easily volatiliz- Volatilizable. Difficultly vola- Non-volatil- able. tilizable. izable. Destitute of me- Some metallic Great metallic Full metallic lus- tallic lustre. lustre. lustre. tre. Negative ten- Both negative More positive Full positive ten- dencies, and positive tendencies. dencies. tendencies. The following will exhibit the relations of some of the most important compounds : — Hydrides. Chlorides. Oxides. Sulphides. -otis. -ic. -ous. -z'c. -ous. -ic. NH 3 NCI3, .... N 2 3 , N 2 5 PH 3 PCI3, PC1 5 P 2 3 , P 2 6 P 2 S 3 , P 2 S 5 AsH 3 AsCl 3 , AsCl 5 As 2 3 , As 2 5 As 2 S 3 , As 2 S 5 SbH 3 SbCl 3 , SbCl 5 Sb,0 3 , Sb 2 5 Sb 2 S 3 , Sb 2 S 5 BiCl 3 Bi 2 3 , Bi 2 5 Bi 2 S 3 .... Vanadium, Columbium and Tantalum belong to this group, but are rare metals and as yet of little importance. NITROGEN occurs uncombined in the atmosphere ; com- bined in some mineral, and all vegetable and animal bodies, especially in the more highly organized tissues. Prepared most easily by burning phosphorus in a confined PART I. — INORGANIC CHEMISTRY. 53 space until the oxygen is removed from the air. 71 Prepared in this way it contains small quantities of other gases found in air. To prepare it pure, heat ammonium nitrite (NH 4 N0 2 = 2 H,Oi-N 2 ). Physical Properties. — A colorless, tasteless, odorless gas, a little lighter than air. Chemical Properties. — Little tendency to combine with other elements, and its compounds, once formed, are very prone to Fig. 22. decompose, either with violent decomposition 72 or gradual putre- faction ; neither combustible nor a supporter of combustion ; negatively poisonous. The Atmosphere. Air, considered by the ancients one of the four elements (fire, earth, air and water), is neither an ele- ment nor a compound. It is a mixture, 73 mainly of nitrogen and 71 A flat piece of cork floating on water supports a capsule containing a bit of phosphorus carefully dried. This is ignited and immediately covered with a bell jar. The jar is filled with a dense white cloud from the combustion, which ceases only when the oxygen is all consumed. At first the air expands, and some may be forced out. Upon cooling, the water rises to take the place of the oxygen, the white fumes gradually dissolve in the water, and the nitrogen is left clear and comparatively pure, Fig. 22. 12 To tincture of iodine add excess of ammonia water. Filter to separate the precipitated iodide of nitrogen. Put portions of this on separate bits of paper and set aside. When dry they explode on the slightest touch. 73 Proofs that air is a mixture: (i) Its constituents are not in atomic pro- 54 ESSENTIALS OF CHEMISTRY. oxygen, the function of the former being to dilute the latter. Mil- ler gives the average composition of air as follows : Volumes. Nitrogen °. 77-95 Oxygen 20.61 Carbon dioxide * 03 Aqueous vapor 1 .40 Also traces of nitric acid, ammonia, sodium chloride, ozone, dust, bacteria, germs, etc. In the neighborhood of large cities various other substances are poured into the air from manufactor- ies. Yet, owing to the rapid diffusion of gases, the composition of the air is almost the same everywhere. Watery Vapor, The higher the temperature the more water air will hold. A warm, dry, air, when cooled, will appear damp, and the temperature at which it begins to deposit its water is its dew point. A cold, damp air, when heated, becomes capable of holding more water, and appears dry, hence the necessity of sup- plying water to the heated air of our rooms in winter, especially in cases of bronchitis or catarrhal croup. Even in health, a very dry air irritates the air passages, produces dryness of the skin and malaise ; while a very moist atmosphere retards evaporation from the skin and lungs, raises the body temperature and becomes oppressive. Suspended Matters in air are of a great variety of substances. The irritation of dust incident to certain trades may cause chronic bronchitis, emphysema and phthisis. Germs floating in the air are believed to be the cause of many contagious, infectious, and malarial diseases. The best disinfectants 74 are (a) free ventila- portions; (2) air can be. made by mechanically mixing the gases; (3) sol- vents may remove one gas without affecting the others, each dissolving accord- ing to its own solubility. 14: Disinfectants destroy the power to infect, whether it be due to germs or other agents. Germicides destroy germs. Antiseptics prevent putrefaction. Antizymotics prevent fermentation. Deodorizers destroy offensive odors. PART I. — INORGANIC CHEMISTRY. 55 tion and consequent dilution ; (b) chlorine, bromine, iodine and formaldehyde, sulphur dioxide and formaldehyde. Argon, Helium, &c. Argon was discovered in 1894 by Lord Rayleigh and Prof. Ramsay, as a residue (1 per cent.) after removing all the oxygen, nitrogen, etc., from air. A colorless, odorless gas that out-nitrogens nitrogen in its lack of affinity. Helium, (yfaog, the sun) has, from its line in the solar spectrum, long been known to exist in the sun's atmosphere, but was not discovered till 1895, when Ramsay obtained it from certain minerals. Krypton and Neon are two new elements Ramsay and Travers claim to have recently discovered. AMMONIA, NH 3 . — Occurs in the effluvia from decomposing nitrogenized organic bodies ; for nitrogen, and hydrogen will not combine except in the nascent state (see page 33). First obtained from the destructive distillation of camels' dung near the temple of Jupiter-Ammon in Libya; hence called " ammonia." Later it was obtained by heating clippings of hides, hoofs and horns, 75 especially of deer (the hart) in closed iron retorts, and was called " spirit of hartshorn." Coal contains about two per cent, of nitrogen, a part of which in the manufacture (destructive distillation) of coal-gas comes off as ammonia. In washing the coal-gas the ammonia dissolves, and this solution is now its com- mercial source. Preparation. — Ammonia may be prepared in various ways, as above suggested. In the laboratory it is usually obtained by driv- ing it off from the commercial "aqua ammoniee " by heat. Physical Properties. — Transparent, colorless gas of an irritating odor ; condenses under a pressure of about 100 pounds to square inch (6 or 7 atmospheres) at ordinaiy temperatures, into a color- 75 Mix some Ca2HO, KHO or XaHO with some nitrogenized organic sub- stance, as albumin, wool or, best of all, and easily obtainable and agreeable, chipped dried-beef. Heat in a test-tube. Ammonia gas is evolved, recog- nized by its odor, alkalinity, or by white fumes when a glass rod is thrust into the mouth of the tube. 56 ESSENTIALS OF CHEMISTRY. less liquid. 76 Ammonia is exceedingly soluble, water dissolving from 500 to 1000 times its own volume. 77 Chemical Properties. — Ammonia is not ordinarily combustible, though it may be made to burn if mixed with a small amount of oxygen. It is alkaline in solution, and combines with acids to Fig. 24. Fig. 23. form the well-known ammonium salts which will be considered in another group. Uses. — Ammonia, liquefied in iron drums strong enough to resist the pressure, is sold in large quantities for ice-making. Water of ammonia is largely employed in chemistry, pharmacy and medicine, the gas from it being often administered in syn- cope, chloroform narcosis, etc., but care must be taken lest its too 76 Make ammonium-silver chloride by passing ammonia gas over silver chloride. Seal this in a bent glass tube (Fig. 23). The end containing the compound is heated in a water-bath, while the other is cooled in an ice mixture. Ammonia gas is driven off from the compound, and condenses into a colorless liquid in the cold end of the tube. 77 The absorption of ammonia gas by water may be illustrated by filling a large bottle with the gas by upward displacement, and closing the mouth with a rubber cork through which passes a glass tube sealed at its outer end. If this sealed end be plunged under water and broken off, the water rushes in forming a beautiful fountain (Fig. 24). If the water be colored red with litmus, it will become blue as it enters the bottle, showing that the water has become alkaline. PART I. — INORGANIC CHEMISTRY. 57 liberal use on the unconscious patient cause spasm of the glottis or set up a dangerous bronchitis. Tests, — The gas may be recognized by (a) its smell, (/£) white fumes with HO, (c) turning moistened red litmus blue. Its compounds must be warmed with a strong alkali 78 to liberate the ammonia gas, which can then be recognized as just described. A most delicate test is Nessler's Reagent, 79 which gives a yellowish brown with ammonia or its compounds. Fig. 25. Nitrogen Oxides. M onoxide — N 2 + H 2 = 2HNO = Hyponitrous acid. Dioxide — N 2 2 . No corresponding acid. Trioxide— N 2 3 + H 2 =■ 2HN0 2 = Nitrous acid. Tetroxide — N 2 4 . No corresponding acid. Pentoxide— N 2 5 -f H 2 = 2HNO3 = Nitric acid - 78 Mix lime with NH 4 C1 and heat in a test-tube. Test the NH 3 as above de- scribed, and expose to it a paper moistened with CuS0 4 solution, and note the deep blue ammonio -sulphate of copper formed. 79 Nessler's Reagent. Dissolve 35 gm. of Kl in 100 Cc. of water and 17 gm. of HgQ 2 in 300 Cc. of water; add the first to the second until the precipitate first formed is almost re-dissolved. Then add 20 per cent. NaHO solution, enough to make one liter. 58 ESSENTIALS OF CHEMISTRY. Nitrogen Monoxide — N 2 {Nitrous Oxide — Laughing Gas), — Prepared by heating ammonium nitrate, 80 as shown in Fig. 25. NH 4 N0 8 = N 2 + 2H 2 0. Physical Properties. — Colorless, odorless gas, of sweetish taste. Dentists keep it liquefied under pressure in iron cylinders. Chemical Properties. — By the ease with which it gives up its O it is a supporter of combustion and life, next to O itself. Medical. — Inhaled, diluted with air, it produces exhilaration of spirits, muscular activity, and then complete anaesthesia. Used in dental and other brief minor operations. Nitrogen Dioxide — N 2 2 {Nitric Oxide). — Prepared by action of nitric acid on copper : — S1 3C11 + 8HNO3 = 3Cu(N0 3 ) 2/ f- 4H 2 + N 2 2 . A colorless gas, which, when coming in contact with free O, forms red vapors of N 2 8 and N 2 4 ; hence a test for free O. Unlike N 2 0, it is not a supporter of combustion, except to substances very avid of oxygen. 82 Nitrogen Trioxide — N 2 3 and Nitrous Acid — HN0 2 . — Ni- trous acid is known only in its salts, the nitrites. These are pro- duced in nature by the oxidation of nitrogenous organic matter in the presence of certain forms of microscopic life. This nitrification occurs in waters polluted with organic matter, 50 Put 5 Cc. of NH 4 N0 3 in a side-neck test-tube with cork and delivery-tube (Fig. 8). Collect gas over warm water; note that glowing match-stick bursts into flame when thrust in. 81 Copper turnings, clippings, or wires are placed in a flask, and nitric acid diluted with half its volume of water is poured in, and the flask set in cold water. Red fumes soon fill the flask, but when these have escaped the gas appears colorless, turning red, however, on reaching the air. The colorless gas is collected over water. 82 The student might use the apparatus shown in Fig. 7, but must be exceed- ingly careful not to inhale the fume's. Collect two cylinders of N 2 2 : (a) Into one introduce burning phosphorus; it burns with great brilliancy, (&) To the other add a few drops of CS 2 and agitate to mix the vapor and gas; then ignite with a flame, and note the blinding, bluish-white blaze, remark- ably rich in chemical rays. PART I. — INORGANIC CHEMISTRY. 59 and normally in the soil, where the acid so formed combines with bases. Hence, nitrites in water is evidence of previous contami- nation with nitrogenous matter. Further oxidation forms nitrates. Nitrcgfn Tetroxide — N 2 4 — occurs in company with N 2 3 in the brown fumes given off whenever nitric acid is decomposed, as in certain laboratory and manufacturing processes.^ The effect of breathing air thus contaminated is to produce chronic inflamma- tion of the respiratory tract. If the vapor be more concentrated the effects are more acute and serious. At first there is only a cough, in two or three hours a difficulty in breathing, and in about twelve hours, death. The remedy is ventilation. Nitrogen Pentoxide — N 2 5 — is of no medical interest. Nitric Acid — HN0 3 {Aqua Fortis) — occurs in traces in the atmosphere and as nitrates in the soil. (See Nitrites.) Fig. 26. Prepared 'by distilling a nitrate with sulphuric acid/ 1 2KXO3 + H 2 SO, = K 2 SO, - 2HX0 3 . S * 83 In a side-neck test-tube (Fig. 26) strongly heat some dry Pb 2NG 3 and condense the fumes in a test-tube in a freezing mixture of ice and salt. 81 In the laboratory nitric acid may be prepared with the apparatus shown in Fig. 15. Equal parts of sodium nitrate and sulphuric acid are heated in the retort A. The nitric acid produced is vaporized by the heat and recondensed in the tube B kept cool by an outer tube C, through which flows a stream of water from an elevated vessel. The acid is collected in the vessel D. 86 The student had better use the apparatus shown in Fig. 26. 60 ESSENTIALS OF CHEMISTRY. Physical Properties. — Heavy liquid and colorless, but if old and exposed to light it becomes yellow or orange from presence of N,0 2 and N 2 4 . Like all nitrates, it is soluble in water. Chemical Properties. — HN0 3 readily gives up a portion of its oxygen, and hence is an energetic oxidizer. Many organic sub- stances, as cotton, glycerine, etc., undergo in contact with HNO* a process of nitration in which the radical N0 2 is substituted for H, and they (gun-cotton, nitroglycerine, etc.) are much more un- stable, combustible, and even explosive. HN0 3 coagulates albu- min and stains albuminoid bodies a permanent yellow. 86 Medical Properties. — The officinal nitric acid contains 68 per cent, and the dilute 10 per cent of HNO :> The strong acid is a a powerful escharotic, but the dilute is a valuable digestive tonic. PHOSPHORUS (light-bearer) . Occurs, combined with oxygen, in the ancient, unstratified rocks. These disintegrate and form soil, from which the phosphorus passes into the organisms of plants, and thence into the bodies of animals, being present in every tissue, but mainly stored up in the skeleton. First isolated by Brandt in 1669 from urine, but now obtained exclusively from bones. Physical Properties. — A soft, yellow, solid, resembling un- bleached wax. 87 86 Of the acid formed in the preceding experiment : (a) Put a drop on white of egg or fresh meat, and note that the albumen is coagulated. (d) Place a drop on some dry albuminoid substance, as skin, hair, wool, etc., and note the yellow stain, not discharged by alkalies. (c) Moisten a bit of paper or cloth with the acid and dry gently; note that it burns like tinder. (d) Add a few drops to a solution of indigo or other organic dye, and note the oxidizing and bleaching effect. (e) To some turpentine warmed in a test-tube, add the strong acid; it in- flames. (/) Lay a drop on clean copper or tin, and note the red fumes. (§•) Mix in a test tube equal volumes of H 2 S0 4 and an aqueous solution of FeSG 4 , and when cool, add HNO H or any other nitrate; note a brown colora- tion, disappearing on heating or even shaking. b ~ When heated to 500° F. in an atmosphere incapable of acting upon it, phosphorus is converted into a reddish-brown powder, which, unlike ordinary phosphorus, is not poisonous, not inflammable, and insoluble in the ordinary solvents. PART I. INORGANIC CHEMISTRY. 6 1 Chemical Properties, — Very inflammable/ 5 so kept under water ; exposed to the air, it undergoes a slow combustion, emits the odor of ozone, and is luminous in the dark. Physiological — Liable to inflame from careless handling, and burns by it are difficult to heal. In medicinal doses, a nerve tonic and aphrodisiac ; in larger quantities a virulent poison and gastro-irritant. Sometimes given with homicidal intent, but more frequently taken accidentially as rat poison, tips of matches, etc. Workmen in match factories suffer from irritation of stomach and bowels, caries of teeth, necrosis of bones, especially of lower jaw, and from fatty degeneration of various organs. This maybe pre- vented by using the red allotropic variety, which is harmless. No good antidote. Evacuate the stomach ; give copper sul- phate 8 ' J as emetic and antidote : give old turpentine, the ozone of which oxidizes the P. Avoid fats, for they dissolve it. Tests. — (i) Shines in the dark; (2) emits garlicky odor. Phosphine — PH 3 (Phosphoretted Hydrogen.) — Occurs mixed with other hydrides of P in the gases arising from decomposing animal or vegetable matters, especially under w T ater ; hence seen as the ignis fatuus, or " Will-o'-the-wisp," over marshes and graveyards. Prepared by boiling phosphorus in a solution of caustic potash. 90 Properties. — Colorless gas of a garlicky odor; inflames spon- taneously upon coming in contact w T ith the air ; very poisonous, 88 Dissolve some phosphorus in carbon disulphide. Pour this on a sheet of filter paper hung on a retort stand. Soon the solvent evaporates and leaves the phosphorus in such a fine state of division that it inflames spontaneously. 89 Place a clean bit of phosphorus for a minute in a solution of copper sul- phate. Remove, and note the coating of metallic copper. 1,0 Into a retort, whose delivery tube dips under water in a dish (Fig. 27), add liquor potassae and a few bits of phosphorus. Expel the air by passing hydrogen or illuminating gas through the retort, or by adding a few drops of ether, the vapor of which does the same thing. On applying heat the hydro- gen or illuminating gas or ether vapor first escapes, then come bubbles of PH.,, each of which, as it bursts into the air, ignites spontaneously, forming beautiful rings of white smoke rotating on their circular axes. These may ascend to the ceiling if the air be still. 62 ESSENTIALS OF CHEMISTRY. destroying the oxygen carrying power of the blood, which after death is found to be dark-colored, with a violet tinge. Fig. 27. Oxides and Oxacids of Phosphorus. — These are analogous to those of nitrogen, except that several members are missing and that the oxides, in combining with water to form their respective acids, may take three or two or one molecule of H 2 0, and each oxide thus form three different acids, distinguished by the pre- fixes, " ortho-," " pyro- " and " meta- ; " for example :— P A 1 + 3H 2 = H S P 2 8 = 2H 3 P0 4 = Orthophosphoric acid. Phosphorus J + 2 H 2 = H 4 P 2 7 = Pyrophosphoric acid. 92 Pentoxide.-' 1 I -f H,0 = H 2 P 2 6 = 2HPO3 -= Metaphospboric acid. Rl A little stand in the middle of a dinner plate supports a capsule in which is put a bit of phosphorus freed from adhering water. This is ignited and covered with a bell-jar. The jar is filled with clouds of P,0 5 , which, aggre- gating, fall into the plate like a minature snow storm. 92 Place a few crystals of Na 2 HP0 4 in a dish and heat till it melts and loses a part of its water; dissolve the residue (Na 4 P,0 7 ) in water and test with AgN0 3 solution; note the white precipitate of Ag 4 P 2 7 . PART T. INORGANIC CHEMISTRY. 63 The "ortho-" acids and salts are the ones so generally used that when the " pyro- " and " meta- " are not specified, the " ortho- " are meant. Hypophosphorous Acid. — This acid is seldom prescribed, but the hypophosphites in powder, or better in pill or syrup, are much employed, especially in anaemia, tuberculosis, etc. It should be remembered in prescribing, especially with reducible metallic salts, that the hypophosphites are deficient in oxygen and strong reducing agents. Phosphorous Acid and the Phosphites are seldom prescribed in medicine and of but little importance : prone to oxidize into phosphoiic acid and phosphates. Orthophosphoric Acid. — Never found free, but is widely dis- tributed in its salts, the phosphates, in the tissues of plants and animals, especially in bones, and in the earth, the " phosphate- beds ' ? of our southern sea-coast being its principal source. The officinal acid is, or should be, made from phosphorus and nitric acid. Being the phosphoric acid most used in medicine (the other two are poisonous) it is usually called simply " phosphoric acid." A transparent, sour, syrupy liquid : but when free from water and cold it is in rhombic crystals, the so-called glacial phosphoric acid. Heated above 200 C. (392 F.) it is con- verted into pyrophosphoric and metaphosphoric acid. Phosphoric acid does not coagulate albumin, and in the diluted form is much used as a digestive tonic. Its usual tests are, (a) with AgN0 3j a yellow precipitate soluble in nitric acid and ammonia: (b) with the magnesian fluid of the U. S. P., a white precipitate soluble in acids. 93 ARSENIC. — Arsenic [arsemttn) occurs mostly as sulphide, usually associated with other metals. The ore is roasted, and the resulting oxide heated with carbon (charcoal) yields the metal. This is a brittle, steel-gray crystalline, solid possessing a marked metallic lustre. Pleated out of contact with air it sublimes ; in ^ Boil some match-heads in a test-tube with dilute nitric acid; neutralize with ammonia and test this solution as indicated above for H 3 P0 4 . 64 ESSENTIALS OF CHEMISTRY. air it burns with a bluish-white flame emitting the odor of garlic and white clouds of As 2 3 . It combines with many elements, its compounds with metals (arsenides) resembling alloys. Used in pyrotechny, the manufacture of shot, pigment and fly-poison. All its compounds are poisonous. Hydrogen Arsenide — AsH 3 — Arsine — is of great practical interest to the toxicologist, as its formation constitutes one of the best and most delicate tests for arsenic, for it is formed wherever arsenic finds itself in the presence of nascent hydrogen, i. . Made : PbO - 2HNO3 = Pb(N0 3 ), + H,0. Ledoyen's disinfectant fluid was a solution of Pb(N0 3 )- 2 (one drachm to the ounce), but is no longer officinal. It corrects fetid odors by precipitating H 2 S and NHJHS. Lead Acetate— Pb(C 2 LLA),, or PbAc — Sugar of lead™ Made : PbO + 2HAc = PbAc 2 4- H 2 0. Used in medicine more than any other lead salt. Its solution will dissolve considerable quantities of PbO, forming the solution ,M Onto I Gm. of red lead in a test-tube pour 5 Cc. of dilute HXO ; , and note that the acid attacks and dissolves only the PbO, leaving the Pb0 2 as a dark brown powder. 131 Mix a little dry PbO., with pulverized sugar and note that when the pestle rubs hard against the side of the mortar, the sugar is oxidized by the PbO., and takes fire. U3 Heat 2 Gm. of litharge with 5 Cc. of acetic acid and filter. Allow a few drops of the filtrate to evaporate on a watch crystal and note the colorless prismatic crystals of " sugar of lead." 84 ESSENTIALS OF CHEMISTRY. of the sub acetate of lead, the liquor plumbi sub ace 'talis , U. S. P., Goulard's extract. This is a basic acetate and is sometimes called vinegar of lead. It is astringent, and, like all the lead salts, sedative. Much used as a topical application in erysipelas, acute eczema, and other skin affections ; and diluted {lead water), it is used in conjunctivitis and other mucous inflammations. The following insoluble salts may be made by precipitation from solutions of the preceding soluble ones : l:56 Lead Chloride — PbCl 2 . — Made : Soluble lead salt added to a soluble chloride ; e. g., PbAc 2 + 2HCI = PbCl 2 + 2HAc. Slightly soluble in warm water, but in cold it is always precipitated from solutions of moderate strength ; hence classed with HgCl and AgCl as one of the three insoluble chlorides. Lead Sulphate — Pb*30 4 . — Forms as a white precipitate when- ever a solution of a lead salt is added to a sulphate solution, thus : PbAc 2 + ZnS0 4 = PbS0 4 + ZnAc 2 . Lead Carbbnate — PbCO s — White Lead. Made: PbAc 2 + Na 2 C0 3 = PbCO s + 2NaAc. Commercially, it is made by some modification of the old Dutch method, which consists in covering sheets or bars of lead with the refuse of the wine-press and barn manure. The acetic fumes from the grape husks attack the lead, forming lead acetate, which is decomposed by the carbonic acid (C0 2 4- H 2 0) from the manure. The acetic acid thus liberated combines with another portion of 186 Now test this filtrate for lead, by adding to successive portions the fol- lowing solutions, each containing a negative radical capable of forming an in- soluble compound with Pb : Sulphuric Acid. (PbAc, 4- H 2 S0 4 = 2HAc -f PbS0 4 ) white precipitate. Hydro sulphuric Acid. (PbAc 2 -f H 2 S == 2HAc + PbS) black precipitate. Sodium Carbonate. (PbAc 2 -f- Na 2 C0 3 = 2HAc -f PbC0 3 ) white precip- itate. Potassium Iodide. (PbAc 2 -f- 2KI = 2HAc 2 + Pbl 2 ) yellow precipitate. Potassium Chr ornate. (PbAc 2 -f K 2 Cr0 4 = 2H Ac 2 + PbCr0 4 ) yellow pre- cipitate. PART I. INORGANIC CHEMISTRY. 85 lead, which is again precipitated by the carbonic acid, and thus the process continues until all the lead is consumed. Used for painting, but blackens when air contains ELS. Lead Sulphide — PbS — is formed as a black precipitate when- ever a lead solution is treated with a soluble sulphide, as ELS or NH.HS, Lead Iodide — PbL. — A bright yellow precipitate on adding a soluble iodide to a lead solution ; as, PbAc 2 + 2KI = 2KAc + Pbl 2 Lead Chromate — PbCr0 4 . Made : PbAc, + K 2 CrO, = PbCrO, + 2KAc. Under the name of chrome yellow it is used in painting. Ot late it has been used to color food products. Tests for lead consist mainly in forming precipitates of the fore- going insoluble compounds. Physiological.— All the lead compounds are poisonous. Acute poisoning sometimes occurs from the ingestion of a single large dose of a soluble lead salt. The symptoms are those of gastric irritation. Treatment: Give MgSO. to form the insoluble PbS0 4 . The chronic form of lead intoxication, painter's colic, is true poisoning, and is produced by the continued absorption of min- ute quantities of lead by the skin of those handling it, and by the lungs and stomachs of those living in painted apartments, or using food and drink from leaden vessels or soft and contami- nated water conveyed through lead pipes. There is impairment of digestion, constipation, blue line along the edge of the gums, colic and paralysis, especially of the extensor muscles. Lead once absorbed is eliminated very slowly, having combined with the albuminoids, a combination which is rendered soluble by the administration of iodide of potassium. The treatment for chronic lead-poisoning is to give MgS0 4 , for the double purpose of overcoming the constipation and precipi- tating any lead remaining unabsorbed in the alimentary canal ; also KI to promote the elimination of that which is combined with the albuminoids. Alum is a favorite treatment, seeming to 86 ESSENTIALS OF CHEMISTRY. perform all accomplished by both the MgS0 4 and KI. The par- alyzed muscles must be treated with electricity, so that when the lead is eliminated and the nerve influence returns, it may not find them degenerated past redemption. Potassium Group. (Hydrogen H i ) Lithium Li 7 Ammonium (NH 4 ) 18 Sodium (Natrium) Na 23 Potassium (Kalium) K 39.1 Rubidium Rb 85 Cesium Cs 133 Group Characteristics. — Univalent ; very electro-positive (ex- cept H), so that when combined, unless it be with a strongly electro-negative (acidulous) radical, they form very alkaline com- pounds. The positive affinities, as in the other groups, increase with the atomic weights. All their compounds are soluble. LITHIUM. — Sparingly but- widely distributed in nature, es- pecially in the waters of certain springs. Lightest of the solid elements. Its salts closely resemhle those of sodium. Physiological. — Lithium urate being by far the most soluble com- pound of uric acid, salts of lithium, especially the very soluble citrate and the less soluble carbonate/' 7 are given to gouty per- sons to promote the elimination of uric acid, which accumulates in that disease. But much of the lithium seems to go to neu- tralizing the acid sodium phosphate instead of combining with the uric acid. Test. It colors the flame a beautiful carmine red ; 138 its phos- phate is insoluble in presence of ammonium hydrate. 139 117 Lithium. Tests. Note the taste, reaction and slight solubility (1 in 80) of Li 2 C0 3 ; dissolve a little in HO, avoiding excess of acid, and test the solution . 138 Fla?Jie. Dip end of platinum wire in solution and place in edge of the Bunsen flame and note the carmine-red. 1{9 Phosphate. Into a test-tube pour some Na 2 HP0 4 solution and half as much NH 4 HO and then a few drops of the Li solution, and warm slightly. Note white precipitate of Li 2 HP0 4 . PART I. — INORGANIC CHEMISTRY. 87 AMMONIUM. — When ammonia gas (NH 3 ) combines with an acid, it appropriates the basic hydrogen of the acid and forms a salt in which NIl 4 is the positive radical ; e. g.: NH 3 — HC1 = NH 4 C1, corresponding to KC1 or XaCl; NH 3 -HHO=XH 4 HO, corresponding to KHO or NaHO; NH 3 — HNOg =NH 4 N0 3J corresponding to KNO a or NaNO s ; 2XH, - H 2 S0 4 = (NH 4 ) 2 S0 4J corresponding to K,,S0 4 or Xa,S0 4 . This radical (NH 4 ) plays the role of a metal, like K and Na, and is called Ammonium. Does not exist uncomblned, although Wey] claims to isolate it as a dark-blue liquid metal. 140 We can obtain it as amalgam by the reaction between sodium amalgam and ammonium chloride. 141 Ammonium Hydrate — XH 4 HO — Caustic Ammonia — is formed in solution whenever ammonia gas (NH 3 ) dissolves in water, thus: NH 3 + H 2 = NH 4 HO. It has been already stated that the aqueous solution of a fixed substance is called a liquor ; of a volatile substance, an aqua. In like manner alcoholic solutions of fixed substances are called tinctures, and of volatile, spirits. There are four U. S. P. solutions of ammonia : Aqua ammonia jo per cent. Aqua ammonia fortior 28 " Spiritus ammonia 10 u Spiritus ammonia aromaticus. " *' ll0 XOTE. — The siipposed free ammonium. Sodio-ammonium is prepared by heating sodium in a sealed tube with ammcnia gas. This is in turn heated with ammonium chloride in a sealed tube. A dark -blue liquid, with metallic lustre, is obtained, but soon decomposes into ammonia gas and hydro- gen. 141 To some mercury in a test-tube add sodium, small bits at a time. On this sodium amalgam pour a strong solution of ammonium chloride. wSodium chloride and ammonium amalgam are formed. (Xa + Hg) — NH 4 Cl = NaCl — (XH, — Hg). The ammonium amalgam swells up and soon decomposes — (NH 4 — Hg) = XH 3 - H-f Hg — the gaseous XH, and hydrogen escape, and only the mer- cury remains. 88 ESSENTIALS OF CHEMISTRY. In each of these solutions NH 4 HO exists, but has never been isolated, because, whenever we attempt to evaporate the water or alcohol, the NHJHO decomposes into NH 3 4- H 2 0. 142 Ammo- nium hydrate is very alkaline. Ammonium Hydrosulphide — NH 4 HS — occurs in decomposing nitrogenous, sulphurized organic bodies. Made by saturating a solution of NH4HO with H 2 S. A yellowish solution; used as a test reagent. Ammonium Carbonate — (NH 4 ) 2 C0 3 . — Ammonii Carbonas, U. S. P. 143 — Sal volatile — is prepared by heating a mixture of NH 4 C1 and chalk (CaC0 3 ) up to the temperature at which (NH 4 ) 2 C0 3 would be volatilized, when the following reaction will occur. 144 2NH 4 C1 + CaCG 3 = CaCl 2 + (NH 4 ) 2 C0 3 (See Volatility, page 33.") Very prone to absorb C0 2 from the atmosphere and become bicarbonate unless NHJiO be added. Other salts may be made by adding the appropriate acid to the carbonate or hydrate of ammonium. If we use the carbonate we can tell when acid enough has been added by the cessation of effervescence. If the hydrate is used there is no effervescence, and our only guide is the point at which the solution becomes neutral in reaction. This is determined by the use of test papers. These are made of white, unsized paper, steeped in a blue vegeta- ble pigment called litmus, which is reddened by acids and restored to its blue by alkalies. Physiological — The hydrate and carbonate are alkaline irritants, ^Ammonium Tests. NH 4 HO. Pour aqua ammonise into a test-tube and note ( Confirm this by boiling with KHO and getting the odor of ammonia. To the other three salts apply the flame tests, getting the violet for K, yellow for Na, and carmine for Li. 96 ESSENTIALS OF CHEMISTRY. convenience these measuring (volumetric) solutions are each made by dissolving in a liter (iooo Cc. or grams) a number of grams equal to the molecular weight of the substance as com- Fig. 40. Fig. 42. Fig. 41. Q pared to one atomic weight of hydrogen, counting in of course the water of crystallization, if any, entering into the molecule. So a certain volume of one solution is exactly the chemical PART I. INORGANIC CHEMISTRY. 97 equivalent of the same volume of another solution. Such solu- tions are called normal volumetric solutions. Whenever a more dilute solution is desired, it is made one-tenth or one-hundredth of the normal strength and called a decinormal or centinormal solution. The necessary apparatus consists only of a graduated pipette Pig. 40, a liter-flask Fig. 41, and a burette Fig. 42. A burette is a long narrow tube with some sort of a stop-cock at its lower end and with accurate graduations by which the amount of liquid drawn ofT can be accurately read. To estimate the quantity of an alkali or of an acid in a specimen, a certain volume of it is measured out and a few drops added of an " indicator," usually a dye-stuff that will change color at the point of neutralization and mark the end of the reaction. Then after first noting the height in the burette of the test solution, this is added cautiously, especially towards the end, with con- stant stirring until the color changes (the end of the reaction). The amount of the test solution used from the burette is read off, and from this the quantity of the opposite substance in the speci- men is easily calculated. 166 Calcium Group. Calcium, Ca 40 Strontium, . . ' Sr 87.5 Barium, Ba 137 Bivalent ; their oxides and hydrates are very alkaline, but of an earthy character. Their positiveness or basicity is in the order of the atomic weights. Their carbonates are decomposable by heat and insoluble in water, unless it contains FLCO3 in solution. Their sulphates decrease in solubility from the slightly soluble calcium sulphate to the extremely insoluble barium salt. 166 Exercise. Measure into a beaker 5 Cc. of KHO solution and add a drop or two of phenolphthalein, and note that it instantly turns pink. Now add the acid test solution very slowly and with constant stirring until the pink sud- denly disappears. Then multiply the number of cubic centimeters cf the test solution used by the factor for KHO (equivalent in icoo being .0561). In a similar way "titrate" solutions of HC1, etc., for practice. 98 ESSENTIALS OF CHEMISTRY. CALCIUM. — Never free, but its compounds are very abundant, as limestone, 167 gypsum, etc. Calcium salts are necessary to animal life, the teeth and bones consisting mainly of calcium phosphate. Calcium Chloride — CaCl 2 . Made : W8 CaCO a + 2HCI = CaCl 2 4= H 2 + CO,. A white salt ; very avid of water and deliquescent ; used to dry gases. Calcium Carbonate — CaC0 3 . — Abundant as limestone, marble, corals, chalk, and shells of the Crustacea, mollusks, etc. Chalk consists of microscopic shells. Precipitated chalk is made 169 by adding a soluble carbonate to a soluble calcium salt, as : — Na 2 C0 3 -\ CaCl 2 = 2NaCl + CaC0 3 . The precipitate (CaC0 3 ) may be separated from the NaCl in solution, by — (a) Filtration. — Pouring the mixture into a cone of filter paper placed in a funnel, when the water with the dissolved salt will pass through, leaving the insoluble portion (the precipitate) on the filter, (b) Decantation. — Allowing the precipitate to settle to the bottom, and pouring off the clear fluid. In either case the precipitate may be freed from any remaining NaCl by adding pure water and repeating the process. CaC0 3 is slightly soluble in the presence of free H 2 C0 3 . Calcium Oxide — CaO — Lime, quicklime; calx, U. S. P. — A white solid ; made by heating limestone m in furnaces called kilns. CALCIUM. 167 Flame. Dip a little lump of marble into HC1 and hold it in the Bunsen flame — a red flash. 168 To an excess of chalk in a test-tube add dilute HC1. Note effervescence of C0 2 , and when it ceases filter or decant. 169 To the clear solution add some carbonate (as of K, Na or NH 4 ) and note white " precipitated chalk." 170 In a side-neck test-tube with delivery tube generate C0 2 from HC1 and lump of marble. Conduct the gas into lime-water. Note that CaC0 3 is at first precipitated and afterwards redissolved by the C0 2 . 171 Heat a little lump of marble white-hot. Note that it loses its crystalline appearance, and becomes CaO. PART I. — INORGANIC CHEMISTRY. 99 CaC0 3 -= CaO + C0 2 . When water is added to CaO there is a violent chemical union, great heat is evolved, and a hydrate is formed 17 ' 2 thus : — CaO +- II 2 = Ca(HO) 2 . Calcium Hydrate — Ca2HO — Slacked lime. — A white odorless powder ; very slightly soluble in water, less than one grain to the ounce, but enough so to give "lime-water " {liquor calcis, U. S. P.) a decidedly alkaline taste and reaction. The presence of sugar greatly increases its solubility (liq. calcis saccharatus, Br.). Chlorinated Lime — Chloride of lime, bleaching powder, calx chlorata, U. S. P. — is a mixture of chloride of calcium (CaCL) and calcium hypochlorite (CaCIO 2 . It is made by passing chlorine gas over slacked lime until it ceases to be absorbed. It is white, moistens on exposure to the air, absorbing C0 2 and giving off CI. It is employed as a source from which to get a gradual supply of chlorine for disinfecting and bleaching purposes. Calculi Sulphate — CaS0 4 173 — occurs native as gypsum, which, when heated, loses its water of crystallization 171 and forms a white amorphous powder called plaster-of -Paris. If this plaster be mixed with water enough to form a creamy liquid, it will re-crys- talize or "set" into a hard compact mass. 175 Much used in sur- gery to make casts to hold broken limbs in position. Very slightly soluble in water. 176 172 Let the CaO cool, and then drop it into a test-tube and add a few drops of water. Note that it combines with the water, swells up and the tube feels hot. 173 To an inch (about 5 Cc.) of CaCl 2 solution add a few drops of MgS0 4 and note white precipitate of CaS0.2H 2 0. 174 Heat carefully in a test-tube a lump of natural gypsum (CaSO r 2H.,0) or fragment of an old plaster cast. Note that the water of crystallization escapes and condenses on the sides of tube and the gypsum loses its crystalline char- acter. 175 Mix some plaster of Paris into a paste with water and pour into a pill box; press into the surface a greased coin or key. After it " sets" remove the coin or key and the pill box, and note the cast and the impressions. 176 To water that has been standing on CaS0 4 in a test-tube add BaCl 2 and note white precipitate of BaS0 4 , showing the extent to which CaS0 4 dissolves in water. tf& IOO ESSENTIALS OF CHEMISTRY. Calcium Phosphate — Ca 3 (P0 4 ) 2 . 178 It is the most abundant mineral ingredient of the body ; is in every tissue and fluid, especi- ally the teeth and bones, to which it gives hardness and rigidity. A white tasteless powder, soluble in dilute acids. Dissolved by lactic acid, it is given as syrupus calcii lactophosphatis, U. S. P., in scrofula, rickets, and other diseases of defective nutrition. Calcium Oxalate— CaC 2 4 , or CaOx — occurs in the juices of some plants and in the urine. Obtained as a fine white crystal- line powder when a soluble oxalate is added to a calcium solu- tion. 177 Insoluble in water or acetic acid, but soluble in the mineral acids. Calcium Carbide — CaC 2 . — This new compound, 179 important commercially as a cheap source of the valuable illuminant acety- lene and interesting chemically as bridging over the chasm between inorganic and organic substances, and enabling us to make an organic compound directly from the elements, w T as discovered almost accidentally a few years ago. A young man was operating an electric furnace in a small aluminum works on the little river Spray, in North Carolina, and happened one day to throw in some lime and coal. 'Instantly they fused into a dark lustrous mass, which he soon threw into the mill-pond. The vigorous bubbling of gas which ensued completed the discovery of a new and cheap method of manufacturing acetylene, (CaC 2 + 2H 2 = Ca(2HO) 2 4- C 2 H 2 ). Acetylene is exceedingly rich in carbon, and burns with a smoky flame, but with a proper admixture of air gives a light of intense whiteness and power. Hard Waters are such as contain mineral matters, especially calcium (lime) compounds. Often water, in passing through the soil, becomes highly charged with carbonic acid, and dissolves 177 Repeat preceding, adding oxalic acid (H 2 C 2 4 ), and note white precipi- tate of CaC 2 4 , insoluble in alkalies and weak acids but soluble in strong HC1. 178 To a calcium solution add Na.,HP0 4 and note white precipitate of Ca 3 (POJ 2 , soluble even in weak and dilute acids. 179 Acetylene. Into a beaker of water drop a small lump of CaC 2 and note a copious, white precipitate of Ca(2HO) 2 and a rapid bubbling of C. 2 Ii. 2 , which is easily recognized by its pungent odor and bright smoky flame when ignited. PART I. — INORGANIC CHEMISTRY. IOl considerable amounts of CaCO s , and is hard. This is called temporary hardness, because on exposure or boiling, the carbonic acid is driven off, the CaC0 3 is precipitated, and the water be- comes soft. The solubility of CaSO^ does not depend on the presence of carbonic acid, and so boiling will not precipitate it. So water impregnated with CaSO^ is said to be permanently hard. Drinking-water should contain a small quantity of lime ; but very hard water impairs digestion. Hard water is unfit for washing, because the soluble alkali soap reacts with the lime salt to form an insoluble lime-soap. 180 STRONTIUM. — This is a yellowish lustrous metal, occurring never free but always in compounds resembling and analogous to those of calcium, but far less abundant. Through the studies of Laborde, See, Solomon and others, strontium has recently come to be recognized as the best base for iodine, bromine, salicylic acid, etc., as it is non-toxic, sedative to the stomach and is said to have a peculiar nutritive influence. Since strontium colors the flame red 182 its salts, especially the nitrate, are used in pyrotechny to make "red fire." BARIUM. — Of little interest to the medical student, except la0 Half fill two test-tubes, one with distilled and the other with hard water; add to each a few drops of soap solution and shake thoroughly. Note that the distilled water quickly " lathers " and that the liquid is felt to strike the glass softly; and that the hard water strikes hard and does not lather, but forms a precipitate or curd (calcium soap). 181 Estimation of Hardness. To ico Cc. of the water in a clear vial add gradually from a burette the " standard soap solution," shaking after each addition and stopping when a permanent lather appears. Each Cc. of soap solution used represents one degree of hardness, i. e., I part of CaC0 3 in ioo,- ooo parts of the water. A water with not over rive degrees of hardness is classed as a soft water. lc - Strontium. Flame. Dip platinum wire into solution of Sr(N0 3 ) 2 and note the red color it gives the Bunsen flame. 183 To solution of CaS0 4 in a test-tube add a strontium solution and note that SrS0 4 is precipitated, being more insoluble than CaS0 4 . 184 Barium. Carbonate. Add Xa 2 C0 3 to BaCL, solution and note the white precipitate of BaC0 3 . 185 Heat white-hot a lump of native BaC0 3 (witherite) ; add the resulting BaO to water and note that it "slakes" with evolution of heat and dissolves forming a solution of Ba(HO) 2 . 102 ESSENTIALS OF CHEMISTRY. that its compounds are poisonous. Barium sulphate is very in- soluble;' 8 " hence (i) the antidote of barium is some soluble sul- phate, and (2) barium solutions (nitrate and chloride) are delicate tests for sulphates, and vice versa, (See Insolubility} Barium gives the flame a green color; 188 hence used (nitrate) in pyrotechny to make the green or Bengal light. Magnesium Group. Magnesium, Mg 24 Zinc, Zn 65.3 Cadmium, Cd 112 Group Characteristics. — Bivalent ; bluish white-lustrous metals ; quite permanent in air, but when highly heated they volatilize and ignite, burning with a bluish-white light very rich in chemical rays. Magnesium is sometimes classed in the calcium group, but it is more closely allied to zinc. Magnesium. — Never free; abundant in magnesian limestone (CaC0 3 .MgC0 3 ). Asbestos, meerschaum, and soapstone are native silicates. Most natural waters contain its salts. Silvery- white metal ; burns with a brilliant white light, rich in chemical rays, and used in photographing caves and other dark places. 189 Magnesium Sulphate — MgS0 4 — occurs in the waters of various springs, as those at Epsom ; hence often called Epsom salts. Made artificially from the native carbonate, thus : — MgC0 3 + H 2 S0 4 = MgS0 4 + (H 2 + CG 2 ). White, crystalline, soluble salt, of a nauseous bitter taste. It is 186 Sulphate. To a barium solution add a soluble sulphate and note white precipitate of BaSO + . Let the precipitate settle, then pour off supernatant liquid and add HN0 3 and boil : it does not dissolve. 187 To a barium solution add K 2 CrO + : note yellow precipitate, insoluble in water but soluble in nitric and hydrochloric acid. 188 Flame. Dip platinum into a solution of BaCl 2 and note that it colors the flame green. 189 Magnesium. Metal. Seize a piece of magnesium ribbon with the for- ceps; note its properties and then hold it in the Bunsen flame and note that it burns with a blinding bluish-white flame into a white powder of magnesia (MgOj. PART I. INORGANIC CHEMISTRY. IO3 a popular purgative. The nauseous taste and gripirg may be obviated by adding sulphate of iron, as in Crab Orchard salts, or aromatics, or acids, by free dilution. Magnesium Citrate is the most pleasant of the saline purga- tives. Usually given as the liquor magnesii citratis, which is prepared by adding a solution of citric acid to MgC0 3 , and bottling immediately to retain the C0 2 - Magnesium Carbonate — MgC0 3 — occurs native. For medi- cinal purposes it is prepared by precipitation, thus : 190 MgS0 4 — Na 2 C0 3 =s Na 2 S0 4 + MgCO s . Similar to chalk in its physical and in its chemical properties. Magnesium Oxide — MgO — Magnesia. Made like CaO, by heating the carbonate, 191 but is more mildly alkaline than CaO. MgCO a --= MgO + C0 2 . Insoluble and tasteless (earthy), but its alkalinity is shown by its turning moist red litmus paper blue when the solid MgO is dropped upon it. 19 " Magnesium Hydrate — Mg(HO) 2 . — Formed by precipitating a magnesium solution with potassium or sodium hydrate. Insoluble in water, but, like other salts of magnesium, soluble in the pres- ence of ammonium compounds with which they form double salts. Suspended in water, it is "called milk of magnesia™* Magnesium Phosphates. — These resemble the calcium phos- phates and are associated with them in the body, though in small quantity. The anwionio-magnesium phosphate (MgNH^POJ is 190 To a solution of MgS0 4 add a few drops of Na 2 CO s . Note the white precipitate of MgCO s , which dissolves on addition of NH 4 C1. 191 Heat white-hot a lump of dry MgC0 3 : let it cool and note that it is MgO ("calcined magnesia"), is alkaline to litmus and on the addition of acid dissolves without effervescence. 192 with a dear glass rod rub a bit of this white powder on a bit of mois- tened red litmus paper and note that the litmus gets blue, alkaline. 193 Pour 5 Cc. of MgS0 4 solution in each of two test-tubes: to one* add KHO and to the other NH.HO. Note that NH 4 HO precipitates only half as much Mg(HO).,, the rest being held in solution by the ammonium salt. Add to the smaller precipitate strong NH 4 C1 solution and it dissolves. 104 ESSENTIALS OF CHEMISTRY. precipitated whenever a soluble phosphate in neutral or alkaline solution finds itself in the presence of an ammonium salt, as occurs in the alkaline fermentation of urine. 194 Physiological. Magnesium oxide and hydrate being alkaline and tasteless, are popular antidotes for acids. These and the carbonate are given to correct acid conditions of the digestive tract, and combining with the acids they form soluble salts that are laxative. ZINC. — When heated in air, zinc burns with an intense bluish- white light, forming clouds of oxide. 195 It tarnishes quickly in air or water, but becomes coated with a film of oxide that protects it from further corrosion. Iron coated with zinc (" galvanized iron") will withstand exposure to the weather an indefinite time. Alloyed with copper, zinc forms brass. Pure H 2 S0 4 is unaffected by pure zinc or zinc coated with mercury (amalgamated), unless it forms a galvanic circuit. 196 Commercial zinc is rapidly attacked by most acids. Zinc Sulphate — ZnS0 4 — White Vitriol — is made thus : — Zn + H 2 S0 4 = ZnS0 4 + H 2 . White, soluble salt, resembling MgS0 4 in appearance ; astringent and emetic. Zinc Chloride — Zx£\ 2 —Made :™ Zn + 2HCl-ZnCl 2 f H 2 . A white deliquescent salt, strongly astringent ; severe caustic. Used as an injection or a bath to preserve anatomical subjects. 194 A mmonio- Magnesium Phosphate. To a MgS0 4 solution add NH 4 C1 to prevent the precipitation of Mg(HO) 2 and then NH 4 HO and finally Na 2 HP0 4 . Note the precipitation of ammonio-magnesium phosphate, the so-called " triple phosphate " in fern-like crystals. 195 Zinc. Metal. After noting the color, lustre, weight, hardness, etc., of zinc, hold it in the Bunsen flame with forceps and see it volatilize and burn. 19,i Sulphate. Put bits of zinc in a test-tube and add dilute H 2 S0 4 . Note the heat produced and the vigorous evolution of hydrogen, which test by igni- tion, etc. Pour in a little mercury and agitate : the action ceases as soon as the zinc is amalgamated. Drop in a bit of copper and it begins again. 197 Chloride. To bits of zinc in a test-tube add HC1 and note the reaction, evolution of hydrogen. When action ceases, evaporate a few drops of the solution on a watch-crystal and note crystals of ZnCl 2 . PART I. — INORGANIC CHEMISTRY. IO5 Each of the following mixtures forms a hard, white mass, used for filling teeth : — (a) A strong solution of zinc chloride with zinc oxide. (£) A strong solution of magnesium chloride with magnesium oxide. (e) Zinc oxide with phosphoric acid (zinc oxy phosphate). Zinc Carbonate — ZnC0 3 — is a white, insoluble powder made by precipitation : — ZnSO, + Na 2 C0 3 = Xa 2 S0 4 + ZnC0 3 . Used in medicine as a dusting powder for excoriated surfaces, and in ointment. Zinc Oxide — ZnO — is prepared either by burning metallic zinc or heating the carbonate, ZnC0 3 — ZnO + C0 2 . 198 It is a yellowish-white powder, used externally in ointment \ in- ternally as a tonic and astringent, especially in the night-sweats of phthisis and diarrhoea of children. Zinc carbonate and oxide (pearl white) are often used as white pigment having the advantage of lead carbonate in not being blackened by sulphur compounds and in not being poisonous. Zinc Sulphide — ZnS — is precipitated 1 '" whenever a solution of a zinc salt is added to the solution of a soluble sulphide, unless the solution is acid in reaction. It is the only white sulphide, therefore a test for zinc. Poisoning. — All the salts of zinc that are soluble in the digestive fluids act as irritant poisons. Sodium chloride and organic acids dissolve metallic zinc ; therefore food kept in galvanized iron ves- sels is more or less poisonous, especially since commercial zinc usually contains traces of arsenic. For this reason articles in- 198 Oxide. Heat white-hot a lump of ZnC0 3 and note the resulting ZnO, and that it dissolves with acid without effervescence. 19? Precipitates. Test successive portions of a solution of a zinc salt : (a) add Na 2 C() 3 = white ZnC0 3 ; [b) add KHO = white Zn(2HO).,, redissolved in excess of KHO but not reprecipitated by boiling or by NH + C1; (c) add NH 4 HS = white ZnS soluble in excess and in acids except acetic; (a 7 ) add K 4 FeCy 6 = white Zn^FeCyg, insoluble in HC1. 8 106 ESSENTIALS OF CHEMISTRY. tended for toxicological analysis should never be kept in jars with zinc caps. CADMIUM. — This is a comparatively rare metal; it is found in certain zinc ores ; a bluish-white metal softer than zinc ; 2C0 enters into several important alloys. Its salts resemble those of zinc in uses and properties except that some are employed in photography, and that its sulphide 201 is a bright yellow, insoluble in HC1 and most acid solutions. 202 Aluminum Group. Boron B n Aluminum Al 27 Scandium Sc 44 Gallium Ga 70 Yttrium Yt 90 Iridium In 113 Lanthanum La 1 39 Cerium Ce. 141 Neodymium Nd 141 Praseodymium Pr 144 Samarium Sm 150 Erbium . . E 166 Ytterbium Yb 173 Thallium Tl 203 Group Characteristics. — Trivalent. Boron is so weakly posi- tive that it is a non-metal. The others are rare metals, except aluminum, the most abundant of metals. So many of their com- pounds, especially the oxides, hydrates and silicates, are of a neutral, insoluble, infusible, inert and earthy character that the group is often called "the metals of the earths." BORON occurs in the boric acid of the steam-jets in certain 200 Cadmium. Metal. After noting the physical properties of a bit of cad- mium, heat it under the blow-pipe and note that it burns, but with the forma- tion of a brown oxide. 201 To a solution of CdS0 4 add NH 4 HS and note yellow precipitate of CdS. ** 02 Sulphide. Add HC1 to the cadmium in a test-tube and pass H 2 S and note yellow precipitate of CdS. PART I. — INORGANIC CHEMISTRY. IO7 volcanic regions and in deposits of borax, especially in California and Nevada. Boron has two allotropic forms, amorphous and crystalline, corresponding to the coal and diamond forms of car- bon. Boron colors the flame green. 203 Boric Acid (B 2 3 + 3H 2 = 2H3BO3 = (ortho) Boric acid) was formerly called boracic acid from its relation to borax, the sodium salt from which the element itself was named ; pearly scales," 04 soluble in water and alcohol, feebly acid, slightly bit- terish, almost tasteless, and unirritating. Boric acid alone, or combined with glycerine (boroglyceride) is a very efficient and non-poisonous antiseptic. Borax is official as sodium borate (Na2BiO7.10H.2O) and often called sodium biborate, though it is properly a tetraborate. A soluble, mildly alkaline salt of some antiseptic power, and so is used as a wash for infectious and parasitic inflammations. When fused it combines with various oxides, and is therefore used to clean off metallic surfaces in soldering, brazing and welding. ALUMINUM is never found free, but in the abundance and distribution of its compounds (clay and many common rocks) it ranks next to oxygen and silicon — third among the elements and first among the metals. It is a very light (sp. gr. 2.6) bluish- white malleable metal, practically unaffected by air, water and many acids, though HC1 and the alkalies attack it energetically/ " It is also acted upon by certain vegetable acids, especially in the presence of common salt. Its ores, though abundant, unfortu- nately do not yield the metal on being simply heated with carbon,- 12 203 To a crystal of borax add a few drops of H 2 S0 4 and about 5 Cc. of alcohol; ignite and note the green color the H 3 B0 3 gives the flame. 201 Boron. Boric Acid. Heat 5 Cc. of water and about 1 Gm. of borax in a test-tube; to this saturated hot solution add HC1 and note the separation of white crystals of H 3 B0 3 . 200 Melt 1 Gm. of H 3 B0 3 in an iron spoon (doll tin-spoons can be bought for a few cents a thousand; and it loses its 3ti 2 and becomes a sticky, glassy mass of B 2 3 . 206 Aluminum. Metal. Note the physical properties of a bit of aluminum; that it does not dissolve in R 2 S0 4 , HNO a or NH 4 HO, but that in HC1 or KHO it dissolves readily with the evolution of hydrogen. 108 ESSENTIALS OF CHEMISTRY. but recently devised electric methods are now, especially at Niagara and at Neuhausen on the Rhine, increasing and cheap- ening the output. The metal is especially valuable in its alloys, giving to other metals increased strength, incorrodibility and facility of casting. Aluminum Oxide, AI 2 8 , occurs native as corundum, which when pulverized is emery ; its finely crystallized forms, the sap- phire and ruby, are now also made artificially. Aluminum Hydrate, A!( HO) 3 , soluble in acids or excess of of alkalies, falls as a gelatinous precipitate whenever an aluminum solution is treated with an alkaline hydrate or carbonate.' 20 ' It has such affinity for organic matters that it is sometimes used to purify water, and is largely employed as a " mordant " to fix organic colors in dyeing. 211 Aluminum Chloride — A1 2 C1 6 — Prepared industrially in the manufacture of aluminum. A soluble, astringent salt. It absorbs and combines with H 2 S, PH 3 , and NH 3 . An impure solution is sold as a disinfectant under the name chloralum. Aluminum Sulphate — A1 2 3S0 4 . Made by treating white clay with H 2 S0 4 . It has properties similar to the foregoing. Alum — A lumen. — An alum is a double sulphate of a trivalent and univalent radical, 212 crystallizing in regular octohedra with 12 molecules of water of crystallization. Its constitution may be expressed thus : — R 2 m 3S0 4 .R 2 T SO„ or 2R m R (2SO,). 207 Hydrate. To an aluminum solution (sulphate or chloride) add KHO and note gelatinous precipitate of aluminum hydrate, redissolving in excess of KHO. Note too that the same precipitate is formed ( 208 ) by NH 4 HO; (* 209 ) by Na,C0 3 with evolution of C0 2 ; and ( 210 ) by NH 4 HS with evolution of II 2 S. 211 Mordant. Color an aluminum solution with cochineal and add NH 4 HO; note that the precipitated hydrate takes the coloring matter and settles in red masses (" lakes ") leaving the solution clear. 212 Alum. Mix a solution of A1.,(S0 4 ) 8 with one of K.>SO + and evaporate until it crystallizes. Lay some of these alum crystals on a piece of charcoal and heat mildly with the blowpipe; note that they melt and lose their water of crystallization and become an amorphous mass of " burnt alum." Next heat as intensely as possible and note that the carbon of the charcoal does not reduce the aluminum compound to the metallic state. PART I. — INORGANIC CHEMISTRY. IO9 The trivalent radical (R m ) may be Al, Fe, Cr, or Mn. The univalent radical (*) may be K, Na, NH 4 , etc. So by different combinations of these radicals a variety of alums may be formed. The old potash alum (AL(3S0 4 ) 3 .KoS0 4 ) is giving place in the arts to the cheaper am monium alu m (AL(3S0 4 ) 3 .(NH 4 )._S0 4 ). The ammonio-ferric alum (Fe. J (3S0 4 ) 3 .(NH 4 )oS0 1 ) is also much used in medicine. Burnt alum, alu men exsicca/um, is a white amor- phous powder obtained by heating alum until its water of crystal- lization is driven off. Alum, like^other salts in which the acidu- lous radical predominates, is astringent ; burnt alum, on account of its avidity for water, is a mild escharotic. Aluminum Silicates, very abundant in granite, feldspar, etc., and in the clays resulting from the disintegration of these rocks. Clay remaining where formed, is generally quite pure and white (kaolin or china-clay), but if deposited by water it is usually reddish or brown from admixtures of metallic oxides, especially iron. Kaolin is used in medicine, from its inertness, as a dusting powder and as a vehicle for the application of certain corrosive chemicals. Pottery, earthenware and porcelain are made of clay mixed with some fusible silicate which, on heating, melts and binds the particles of clay together more or less firmly. CERIUM is a rare metal. One of its salts, the oxalate, Ce 2 (C 2 4 ) 3 , is used as a sedative to irritable stomachs, especially in the vomiting of pregnancy. When pure it is a very efficient remedy; but the commercial article is liable to contain salts of lanthanum, neo- and praseodymium, and other allied metals. The other members of this group are of little medical interest. The oxides of some of them — the "rare earths" — especially of cerium, together with zirconium and thorium, are used to make the mantle of the Welsbach burner, which heated in the air-gas (Bunsen) flame gives a strong white light. IIO ESSENTIALS OF CHEMISTRY. X. The Iron Group. Chromium, Cr 52 Manganese, Mn 55 Iron, Fe 56 Cobalt, Co 59 Nickel, Ni . ; 59 Molybdenum, Mo 96 Tungsten (Wolfram), W 184 Uranium, U 240 These are hard metals and all more or less magnetic. By a variation in valence they form two classes of compounds : One in which the atom is bivalent, as in ferrous chloride (FeCl 2 ) ; the other in which the atom is trivalent, as in ferric chloride FeC) 3 . With excess of oxygen they form acidulous radicals, which form the chromates, manganates, and ferrates, with the stronger bases. CHROMIUM. — So named because all its compounds are colored. The metal is of but little use. Its compounds are of great importance to the chemist and of considerable utility in the arts, but few are used in medicine. Chromic Oxide, Cr 2 3 , chromium sesquioxide, is a bright green powder used in paint as chrome-green. 213 Chromium Trioxide — Cr0 3 — is made by treating a strong solu- tion of potassium bichromate with sulphuric acid, thus : — K 2 Cr 2 7 + H 2 S0 4 = K 2 S0 4 + H 2 Cr0 4 + Cr0 3 . The Cr0 3 separates in crimson prisms.' 214 It is a powerful oxidant and a caustic. Sometimes improperly called chromic acid. Chromates. — The principal ones are potassium chromate, K 2 Cr0 4 , a valuable test reagent, and lead chromate, PbCr0 4 , a yellow pigment. 2 M Chromium. Sesquioxide. Rub up together about 5 Gm. of K 2 Cr 2 7 and 1 Gm. starch; ignite this in an iron spoon; remove the K 2 C0 3 by wash- ing and then note the green mass of Cr 2 3 . m Trioxide. Mix together equal parts of strong H 2 S0 4 and saturated solu- tion of K 2 Cr 2 7 . Note as it cools the separation of crimson prisms of Cr0 3 . PART I. INORGANIC CHEMISTRY. Ill Bichromates are not regular acid- or bi- salts, but compounds of a chromate and chromium trioxide. The most important of these is potassium bichromate, K 2 Cr 2 7 , or K,Cr0 4 .Cr0 3 . It forms large, red, soluble crystals. It is added to the sulphuric acid in batteries to oxidize 215 the nascent hydrogen. Chromates may be recognized by their color and by the yellow precipitate on the addition of lead acetate. 222 MANGANESE resembles iron in its properties. Used to alloy- iron in the preparation of c rtain kinds of steel. Its most abun- dant ore is the Manganese Dioxide — Mn0 2 — Black Oxide of Manganese — an insoluble steel-gray powder that readily gives us its extra atom of O. Used in large quantities in the preparation of chlorine and oxygen gas.' 224 Manganous Sulphate — MnS0 4 . Mn0 2 — H 2 S0 4 = MnSO, — H 2 - O. 215 Oxidation. Rinse a beaker with strong alcohol and drop in a crystal ot Cr0 3 and note that the thin film of alcohol ignites; (* 2lh ) moisten a pledget of cotton with absolute alcohol and lay a crystal of Cr0 3 on it, and it ignites; ( 2lT ) boil some match-sticks with battery fluid (K 2 Cr ? 7 10 per cent., water 80 per cent., and H 2 S0 4 10 per cent.), and note that they are consumed with evolution of C0 2 . 218 Chromic Salts (green). To some K 2 Cr.,0 7 solution in a test-tube add HC1 and alcohol and boil. Note the odor of aldehyde from oxidation of the alcohol and the green color of CrCL. (- Iy ) To some K 2 Cr.,0 7 solution add H. 7 S0 4 and alcohol, and boil; note the green color of Cr.,(S0 4 )..; put a few drops on a watch-glass and when it dries, note the crystals of chrome alum (Cr,3S0 4 K,S0 4 ) or KCr(SOJ 2 . 2 -'° Chromates. To a solution of K 2 Cr 2 7 add KHO; note that K 2 Cr0 4 is formed and the solution becomes yellow. To successive portions of this K 2 Cr0 4 add ("') BaCl 2 , and note yellow precipitate of BaCr0 4 ; (- 2i ) Pb(C 2 H 3 2 ) 2 and note yellow precipitate of PbCr0 4 , and ( ;2{ y AgX0 3 and note deep red of Ag 2 Cr0 4 . m MANGANESE. Chloride. Warm some MnO., and HC1 in a beaker, under a hood or in the open air to avoid inhaling the C'l evolved, and filter. As the filtrate is sure to contain iron, add Na,CO s gradually with constant stirring as long as reddish brown Fe^HO) s is thrown down and until the flesh-colored MnC0 3 begins to precipitate, then filter and label MnCl 2 . To successive por- tions of the MnCl 2 solution (-- 5 ) add XH t HS and note a pale pink precipitate of MnS, the only flesh-colored sulphide known, and hence characteristic; ( 226 ) add NH 4 HO and note flesh-colored precipitate of Mn(HO) 2 soluble in excess of NH 4 HO. I I 2 ESSENTIALS OF CHEMISTRY. A soluble, rose-colored salt, employed in medicine and also in dyeing. Manganous Sulphide — MnS — is precipitated whenever a solu- tion of a salt of manganese is treated with NH 4 HS. It is the only flesh- colored sulphide ; hence its formation is a testoi manganese. 225 Manganates. — If a mixture of KHO, KC10 3 , and Mn0 2 is heated together, there results a green mass of potassium mangan- ate, K 2 Mn0 4 . If this is dissolved in distilled water, it forms a green solution, which, on boiling, or even standing awhile, is changed to a purple, owing to the formation of potassium perman- ganate, K 2 Mn 2 8 . 227 The permanganate 2 ' 29 gives up its oxygen so readily to organic matter, at the same time losing its purple color, that it is used as a test for organic impurity in water and as a disinfectant. Physiological. — Associated with iron (i to 20), manganese is a normal constituent of the blood corpuscles ; hence its prepara- tions, like those of iron, are blood tonics. Valuable in amenor- rhcea. IRON occurs abundantly in oxide, carbonate, and sulphide ; occasionally free, as in meteorites. Preparation. — The oxides and occasionally the carbonates are the ones used for the preparation of iron. The oxide is heated in a blast furnace with coal and fluxes (limestone and silicates). The carbon of the coke removes the oxygen from the iron, which melts and sinks beneath the melted fluxes. The fused metal is 227 Borax-bead. Melt in the flame a lump of borax on the looped end of a platinum wire until it loses its water of crystallization and fuses into a clear glass bead; touch this to the manganese solution and again fuse it. Note that the bead is colored violet or amethystine. 228 Manganates. Into a porcelain crucible put equal parts of Mn0 2 , KHO and KC10 8 and heat strongly. When quite cool add water and dissolve out the K 2 Mn0 4 , which is a beautiful green. Pour some of this into a beaker of water and note that it changes to violet, K 2 Mn 2 8 with a precipitate of man- ganic hydrate. 229 Oxidation. To some powdered K 2 Mn 2 8 in a dish add a few drops of H^SOj. and note the odor of ozone. ( 2:{0 J Add a few drops of strong alcohol and it ignites. PART I. INORGANIC CHEMISTRY. "3 then drawn off into sand or iron molds. This is pig, or cast iron, containing 4 to 5 per cent, of carbon. Wrought iron contains little or no carbon ai and steel an intermediate quantity. Properties. — A bluish-gray metal, sp. gr. 7.5 * rusts (oxidizes) when exposed to moist air or water containing air. Reduced Iron. — Ferrum Redactum, iron by hydrogen, Que- Fig. 42. Making Reduced Iron. venne's iron. — It is prepared by heating ferric oxide nearly to redness in a tube through which hydrogen is passed : &i FeA+H 6 = Fe 2 + 3 H 2 0. It is a very fine, dark gray powder, which, if good and fresh, will ignite' 283 on contact with a lighted taper and burn with a red glow ; prescribed in pill form. 231 Iron. Metal. Pour 10 Cc. of dilute H 2 S0 4 into each of two test-tubes. Into one drop a small fragment of cast iron'; into the other some wrought iron, as tacks; set aside, and when all is dissolved note that the cast iron leaves a residue of graphite carbon and the wrought iron leaves no residue. -^ Reduced Iron. In the apparatus shown in Fig. 42 (rather tedious and troublesome for a class exercise) hydrogen is generated from sulphuric acid and zinc in the Wolff bottle, and dried by passing through the U-shaped tube containing calcium chloride. It then passes through the porcelain tube con- taining ferric oxide (subcarbonate, U. S. P.) which is heated to redness in the furnace. After the reduction is completed, the iron should not be exposed to the air until cool, or it will ignite spontaneously. Let the student ( 233 ) (Faraday's experiment) pour a mixture of reduced 114 ESSENTIALS OF CHEMISTRY. CHLORIDES. Ferrous Chlortde — FeCl 2 . — Made by adding iron to hydro- chloric acid until effervescence ceases, thus : — Fe + 2HC1 = FeCl 2 -f H 2 Like most ferrous salts, it is green and prone to oxidize with the formation of the ferric compounds. Ferric Chloride — FeCl 3 — is made by first forming the ferrous chloride as above, and then adding nitric and hydrochloric acids. The nascent chlorine evolved by the nitro-hydrochloric acid con- verts the ferrous into ferric chloride, thus : — 6FeCl 2 -f 6HC1 + 2IINO, = 6FeCl 3 +N 2 2 + 4H 2 0. The liq.ferri chlorirfi, U. S. P., is the aqueous solution. This, when diluted with alcohol, forms the tinct. ferri chloridi, U. S. P. If citrate of potassium or sodium is added to this tincture, the solution loses its styptic taste, does not affect the teeth, and is not incompatible with solutions containing tannin. sulphates. Ferrous Sulphate — FeS0 4 — Copperas, Green Vitriol. — Pre- pay erf: Fe + H 2 SO, = FeSO, + H 2 . 235 - Soluble, green crystals efflorescing upon exposure. A cheap and excellent disinfectant, destroying organic matters by abstracting their oxygen. When given in pill form it is first exsiccated. Furric Sulphate — Fe 2 (S0 4 ) 3 . — Tersiclphate is made by adding iron and gunpowder into alcohol burning m a dinner-plate and note that the iron burns with bright scintillations, while the gunpowder falls through the flame and is not ignited uniil the alcohol is burned away to the surface of the plate. ("***) Make an iron gunpowder by mixing I Gm. of reduced iron, 2 Grn. of sulphur and 3 Gm. of KN0 3 , and note that it burns as quickly and more brilliantly than ordinary gunpowder. 2 5 Ferrous Salts. Dissolve iron filings in warm dilute H 2 SO,. Allow a drop of the solution to evaporate on a watch-crystal and note greenish crystals of FeS0 4 . PART I. INORGANIC CHEMISTRY. 115 nitrosulphuric acid (HN0 3 + H 2 S0 4 ) to a solution of the ferrous sulphate, 241 thus : — 6FeS0 4 -f- 3H.SO, + 2HNO3 = Fe 2 (S0 4 ) 3 -f N 2 2 + 4 H 2 0. Its officinal solution is the liq. ferri tcrsiilphatis. Liq.ferri sub- sulphatis, U. S. P., Monsel's Solution, is prepared similarily to the above, except using only half the quantity of sulphuric acid. Fig. 43. A Dialyzer. Ferrous Hydrate — Fe(HO) 2 — is precipitated on mixing solu- tions of a hydrate and a ferrous salt, 236 as — FeSO, — 2NaHO = Na,SO t 4- Fe(HO) 2 . A green precipitate, which soon oxidizes and becomes brown. Ferric Hydrate — Fe(HO) 3 . — A brownish red, gelatinous mass, precipitated by soluble hydrates from ferric solutions, 24 ' 2 e. g. : — FeCl, -f 3NH 4 HO = 3NH 4 C1 + Fe(HO) 3 . This is the favorite antidote for arsenic, for which purpose it must be freshly prepared and given in large doses. Ferric hydrate Ferrous Precipitates. To successive portions of fresh FeS0 4 solution add : 2: ' ,6 KHO = greenish-white precipitate of Fe(HO) 2 . 2: ' 7 Na 2 C0 3 = greenish-white precipitate of FeC0 3 . 2: ^Nti + HS = black precipitate of FeS. 2 ' 9 K 4 (FeCy 6 ) = pale-blue precipitate of FeK 2 (FeCy 6 ). 2;0 K 3 FeCy 6 = deep-blue precipitate of Fe 3 (FeCy 6 ) 2 . 241 Ferric Salts. To a solution of FeSO + add a few drops each of H 2 S0 4 and HX0 3 . It turns dark-brown, but on heating changes to a light-red solu- tion of Fe 2 (S0 4 ) 3 . Ferric Precipitates. To successive portions of a ferric solution add : 242 KHO = reddish-brown precipitate of Fe(HO) 3 . Il6 ESSENTIALS OF CHEMISTRY. dissolves freely in a solution of ferric chloride, forming a dark red liquid of a styptic taste. If this liquid is put in a dialyzer (Fig. 43), a vessel with a bot- tom of parchment or animal membrane, and suspended in water, the chloride passes out through the membrane into the water. When barely enough ferric chloride remains within the dialyzer to hold the ferric hydrate in solution and the styptic taste has dis- appeared, the liquid is removed and sold under the name of " Dialyzed Iron." Ferric Nitrate — Fe(N0 3 ) 3 . Made: Fe(HO) 3 4- 3 HN0 3 - 3H./) + Fe 3 N0 3 . Liq. ferri nitratis, U. S. P., is a reddish acid liquid. Used as an astringent, especially in dysentery. Ferrous Iodide — FeL. — Prepared: Fe + I 2 = Fel 2 . Sometimes given in pill, but better with syrup, which acts as a preservative as well as a vehicle. Ferpous Carbonate — FeC0 3 — is obtained by adding a soluble (alkaline) carbonate to a ferrous salt,' 287 thus : — FeS0 4 + K 2 C0 3 = K 2 S0 4 + FeC0 3 . It is insoluble in pure water, but slightly soluble in water con- taining carbonic acid, as in chalybeate springs. On exposure to the air it turns red from formation of ferric hydrate ; so it is pre- served by mixing with sugar and honey, as in the ferri carbonas saccharaius, U. S. P. Ferrous Sulphide — FeS 238 - — does not occur native, but is made by heating together iron filings and flowers of sulphur. Used in the preparation of H 2 S. Iron pyrites (FeS 2 ) is a common ore largely used in the manufacture of sulphuric acid and copperas. Scale Compounds of Iron. — These are ferric salts, mostly with 2,3 Na 2 C0 3 = reddish-brown precipitate of Fe(HO) 3 . 2,4 NH 4 HS = black precipitate of FeS. 245 K 4 (FeCy 6 ) = deep-blue precipitate of Fe 4 (FeCy 6 ) 3 216 K 3 FeCy 6 = greenish-brown color. 247 K(CyS) = deep-red color, discharged by HgCl 2 . PART I. INORGANIC CHEMISTRY. 117 organic acids. They do not crystallize readily, but are sold as thin scales. Made by evaporating their solutions to a syrupy consistence, poured upon plates, and when dry peeled off in scales. Often other bases, as potassium or ammonium, together with alkaloids, as quinine and strychnine, are incorporated into the compound. The following are officinal : Ferri citras, ferri et ammonii citras, ferri et quinice citras, ferri et strychnice citras, ferri et am- monii tar iras, ferri et potassii tartras, and ferri pyrophosphas. Physiological. — Iron is a normal constituent of the body, espec- ially of the blood corpuscles, where it performs an important func- tion, as is shown by the great increase of blood corpuscles and of bodily vigor attending its administration. Many of its salts, especially the ferric salts of the mineral acids, are astringent and hemostatic. Iron is eliminated by various organs, but is mainly discharged by the bowels as sulphide, blackening the faeces. COBALT. — Its chief ore is a compound with arsenic, sold under the name of cobalt ox fly stone, for poisoning flies. Its salts are used in preparing sympathetic ink,' 248 for when dried and de- prived of water of crystallization, they are a deep blue, but become almost colorless (slightly pinkish) on regaining it. Writing done with a dilute solution of chloride of cobalt is invisible until warmed, when it becomes blue, the color disappearing when the paper is cooled or moistened, especially in a damp air. NICKEL. — This is a hard, grayish-white metal that does not tarnish in the air. 250 Used to electro-plate instruments made of metals more prone to corrode, and to make cheap coin. Mixed with brass, it forms German silver. 248 Cobalt. Sympathetic ink. Dip a clean pen into a cobalt solution and write on paper (better of pinkish tint). Note that the writing is invisible but becomes deep-blue on carefully drying (avoid scorching) over a lamp, and that it disappears again on cooling by blowing the damp breath on it. 249 Touch a borax bead to a cobalt solution and heat; note the deep-blue color. 250 Nickel. Note the physical properties of the metal and that neither H 2 S0 4 nor HCl affect it much, though HN0 3 attacks it vigorously. Il8 ESSENTIALS OF CHEMISTRY. MOLYBDENUM, TUNGSTEN, and URANIUM are rare metals and of little importance except that some of their com- pounds have found a limited application in chemistry and the arts. Ammonium molybdate is a valuable test for phosphoric acid and the alkaloids, and phospho-molybdic acid is a reagent for alka- loids. Sodium tungstate, Na 2 W0 4 , has long been used to render fabrics uninflammable, and recently has attained considerable popularity as a test for albumin in urine. Uranium salts are used to color glass and impart to it a remarkable fluorescence. Copper Group Copper ( Cuprum) Cu 63.4 Mercury ( Hydrargyrum) 13 g 2co Silver (Argentum) Ag 108 Gold {Auruni) Au 197 Group Characteristics. — Copper and mercury are both univa- lent and bivalent, forming two classes of compounds, "ous" and " u" Silver being only univalent and gold both univalent and trivalent, they do not strictly belong to this group, yet their chemical behavior is much like that of copper and of mercury. They are all very weakly positive and indifferent to the negative radicals, and hence quite permanent in air and water, and at or- dinary temperatures but slowly acted upon by most chemicals. COPPER 255 is usually found combined with sulphur, etc., but often in the metallic state, especially on the southern shores of Lake Superior. Being found free, it was among the first metals Precipitates. To successive portions of a nickel nitrate solution add: 201 KHO = pale-green precipitate, soluble deep-blue by NH 4 salts. 252 NH 4 HO = pale-green precipitate, soluble deep-blue by NH 4 HO. 253 NH 4 HS = black precipitate, slightly soluble in excess of NH 4 HS. 254 Borax bead is colored violet while hot and yellowish-brown when cold. 055 Copper. Metal. Note the physical properties of a bit of copper and that it is attacked very slowly by H 2 S() 4 or HC1, but very vigorously by HN0 3 , part of which decomposes to oxidize the metal with the evolution of the lower nitrogen oxides and the rest attacks the oxide thus formed. PART I. — INORGANIC CHEMISTRY. 1 19 wrought by man, 256 so the bronze preceded the iron age. Cop- per is a red malleable metal ; an excellent conductor of elec- tricity. It colors the flame green. 257 . Cupric Sulphate — CuS0 4 — Blue Vitriol, Blue Stone, — Obtained as an incidental product from silver refineries, copper mines, etc. ; made experimentally by heating copper with strong H 2 S0 4 . Forms beautiful blue crystals, soluble in water, but insoluble in alcohol. If the crystals are heated they lose their water of crystallization and form a white powder, which becomes blue again upon the addition of water. Hence, used as a test for water in alcohol. 258 Like other salts in which the acidulous radical predominates, cupric sulphate is astringent and coagulates albumen. A prompt emetic, but not used as much as ZnS0 4 , because if, by chance, it be not all ejected from the stomach, a gastro-enteritis is liable to be set up. Cupric Hydrate. — Cu(HO) 2 — is formed as a bluish- white pre- cipitate whenever a soluble copper salt is treated with a soluble hydrate, 259 thus : CuS0 4 + 2KHO = K 2 S0 4 + Cu(HO) 2 . When heated, even under water, it decomposes — Cu(HO) 2 ==CuO + H 2 0. Cupric Oxtde — CuO — Black Oxide. — Prepared by heating copper turnings in air. It gives up its oxygen easily, hence used as an oxidizer in organic analysis. v56 Reduction. Heat 1 Gm. of verdigris mixed with Na 2 C0 3 on a piece of charcoal in the reducing blowpipe flame and note the globules of metallic copper set free. ' 2o1 Flame. Dip a platinum wire into a copper solution and note that it colors the flame green. 258 Sulphate. After noting appearance, taste, etc., of a crystal of CuS0 4 , put it into a test-tube and heat carefully; note that the salt gets amorphous white, losing its water of crystallization. When cool add strong alcohol and shake; note that there is little change. Add to the alcohol a few drops of water and shake, and note the presence of water is shown by the CuS0 4 tak- ing again water of crystallization and becoming blue. 259 Oxides. To a solution of CuS0 4 add KHO and note a blue precipitate of Cu(HO) 2 insoluble in excess of KHO. Boil and note that the Cu(OH) 2 de- composes into black cupric oxide and water (Cu(HO) 2 = CuO +H 2 0). 120 ESSENTIALS OF CHEMISTRY. Cuprous Oxide — Cu 2 — Suboxide. — Made by boiling the cupric oxide' 260 with an oxidizable substance, as glucose (copper tests for glucose), which is^oxidized at the expense of the oxygen of the cupric oxide. The precipitate is first yellow (hydrate), but soon becomes a bright red (oxide). Cupric Subacetate or Oxyacetate — sometimes called ver- digris (green-gray) — is made industrially by exposing plates of copper to the acetic fumes of grape husks, etc. It is likely to be formed whenever fruits containing acetic acid are placed in cop- per vessels. Physiological. — Canned fruits, pickles, etc., that have been colored green with copper, and food, especially if acid, that has been cooked or kept in copper vessels, are liable to produce an acute gastro enteritis. Chronic copper poisoning, so called, is perhaps always due to other substances, as lead or arsenic, and should be treated accordingly. Antidotes for acute copper poisoning : Encourage vomiting and give albumen (white of egg), which combines with the copper salt to form an insoluble albuminate ; or iron filings, which will precipitate the copper in metallic state.' 262 ( 26 °) Next add some glucose solution and boil; note that the glucose takes part of the oxygen from the black CuO and reduces it to red Cu 2 G. 261 Hydrates. Precipitate Cu(HO) 2 as in preceding exercise. Then add glucose solution and note that it dissolves the Cu(HO) 2 , forming a deep-blue solution. Boil, and note that the glucose deoxidizes the Cu(HO) 2 and pre- cipitates the yellow Cu 2 (HO) 2 , which rapidly decomposes (Cu 2 (HO) 2 = Cu 2 -f- H 2 0) into water and red cuprous oxide — the mixture having changed from a deep blue solution through green to a yellow precipitate, which in turn changes from yellow through orange to red. This is the alkali-copper test for glucose, as well as the alkali-glucose test for copper; for when substances re- act characteristically, each is a test for the other. Other Tests. Test successive portions of a copper solution as follows : 262 Dip in a needle or other bright bit of iron, and note it is plated with copper. •263 p ass \\^ or add NH 4 HS and note black precipitate of CuS. 264 Add NH 4 HO and note deep-blue solution of Cu(NH a ) 2 S0 4 . 265 To the above ammonio-cupric solution, if not too alkaline, add arsenic water and note bright green precipitate of Paris- green (CuHAs0 3 ). 266 Add K 4 (FeCy 6 ) and a drop of acetic acid and note brownish-red cupric ferrocyanide (Cu 2 FeCy 6 ). PART I. INORGANIC CHEMISTRY. 121 MERCURY is the only metal liquid at ordinary temperatures, and resembles silver in appearance ; hence the names hydrargyrum (water silver) and quicksilver (fluid silver). It is so heavy (spe- cific gravity 13.56) that iron and stone float upon it as corks on Fig. 44. water. (Fig. 44 represents a marble and a ball of iron floating on mercury.) It does not tarnish in the air unless contaminated with baser metals ; dissolves most metals/ 67 except iron, to form " amalgams." m Uses. — Metallic mercury is used extensively in the refining of silver and gold, in thermometers and other instruments, with tin in silvering mirrors, and in many other branches of the arts. Metallic mercury, rubbed up with various excipients until globules cease to be visible, 269 forms several officinal preparations. Rubbed with chalk, it forms "gray powder," hydrargyrum cum creta; with honey of rose and licorice powder, it forms " blue pill," massa hydrargyri; and with lard and suet it forms "mercurial ointment," unguentum hydrargyri. The therapeutic activity of these prepara- tions is due not to the metallic mercury they contain, but to small quantities of mercurous oxide formed by the oxidation of the finely-divided metal. So their strength varies with the thorough- MERCURY. Metal. 267 After noting the physical properties of a small vial of mercury, drop a globule into a dish and add a small shot; note that the mercury and lead combine, forming an amalgam. 268 Drop a globule of mercury into AgNCX solution and watch the growth of the "arbor Diana" a tree-like formation of silver amalgam. 269 Rub up a few drops of mercury in a mortar with a little lard and note how easily the mercury becomes emulsified, the globules soon becoming so small as to be invisible to the naked eye. 122 ESSENTIALS OF CHEMISTRY. ness of the rubbing, the extent of the exposure, and the age of the preparation. Mercurous Iodide. Hgl. Proto- iodide, yellow iodide of mercury, Hydrargyri iodidum flavum U. S. P., is made by precipitation ' m from mercurous nitrate and potassium iodide (Hg(N0 3 )4-KI-KN0 3 +HgI). It was formerly made by rubbing together chemical equivalents, 200 of mercury and 127 of iodine. Some of the blue globules of mercury remaining un combined gave the yellow Hgl a greenish color ; hence it was called green-iodide {hydrargyri iodidui7i viride, U. S. P., 1880). Mercuric Iodide. Hgl 2 . Red iodide, Hydrargyri iodidum rubrutfty U. S. P., is made by precipitation 270 from mercuric chloride and potassium iodide (HgCl 2 + 2KI — 2KCI + Hgl 2 ). This too was formerly made by rubbing together equivalents of mercury (200) and iodine (254). The mercuric iodide is dissolved by excess of either the HgCl 2 or the KI. In precipitating, mercuric iodide is first yellow, but rapidly becomes red. If some of the dry red powder is placed on a sheet of paper and warmed over a lamp, it changes back to yellow, but on shaking or rubbing, the red is restored. These changes in color are due to changes in crystalline structure. Mercurous Nitrate — HgN0 8 — is formed when mercury is treated with cold dilute nitric acid. Mercuric Nitrate— Hg(N0 3 ) 2 . — Acid nitrate of mercury is formed if the mercury be boiled with strong nitric acid. Like all 270 To a drop of mercury in a test-tube add HC1 and note that it is un- affected; wash out the acid and add HN0 3 and note it gradually dissolved, especially if warmed. 271 Mix a dry salt of mercury with twice the amount of Na 2 C0 3 and heat in a dry test-tube. Note that the mercury is reduced and sublimes, forming in the cooler part of the tube a deposit of minute globules of metallic mercury. 272 (Rensch's test.) Boil a strip of bright copper foil in a solution of a salt of mercury; or ( ilA ) (galvanic test) drop a few drops of the solution on the copper foil and with a bit of zinc or iron (a more positive metal) touch the copper through the fluid. Note in either case a plating of metallic mercury on the copper and that the mercury may be distilled off by heating the amal- gamated copper in a dry test-tube. PART I. — INORGANIC CHEMISTRY. 1 23 other nitrates, both of the above are soluble. It enters into the liq. hydrargyri 7iitratis, U. S. P., and " citrine ointment," ung. hydrargyri ?iitratis, U. S. P. Mercurous Sulphate — Hg._S0 4 — is made by digesting sulphuric acid with excess of mercury. Mercuric Sulphate — HgSO, — is made by heating mercury with excess of sulphuric acid. A white, crystalline salt, used in some forms of galvanic batteries. When diluted with water it decomposes into an acid salt, which remains in solution, and a yellow precipitate of oxysulphate, HgSO^HgO, called "turpeth mineral," hydrargyri subsulphas fiavus, U. S. P. 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Substances whose formulae are simple multiples of each other are said to be polymeric, e. g., formalde- hyde (CH 2 0), acetic acid (C 2 H 4 Q 2 ) and lactic acid (C 3 H 6 3 ). When elements manifest this same quality it is called allotropism ; of which we have already noticed instances in coal, graphite and diamond, and in ordinary oxygen and ozone. Hydrocarbons. Hydrocarbons are compounds of carbon with hydrogen only. They are exceedingly numerous and are regarded as derived from CH± in homologous and isologous series. The following table shows the usual classification : Series Radicles Series Radicles Series Series 1 Gen. Gen. 2 Gen. Gen. 3 Gen. 4 Gen. Formula Formula Formula Formula Formula Formula CnH2n — 2. CnH2n — 1. CnH2n. CnH2n — 1. CnH2n — 2. CnH2n — 4. Valence Valence Valence Valence Valence O I II III IV Methane. Methyl. Methene. Methenyl. Methim CH 4 CH 3 CH 2 CH C Ethane. Ethyl. Ethene. Ethenyl. C0H3 Eihine. Ethone. C 2 H a C. 2 H 5 C 2 H 4 C 2 H 2 C 2 Triiane. Trityl. Tritene. Tritenyl. Tritine. Tritone. C 3 H 8 C 3 H 7 C 3 H 6 C 3 H 5 C 3 H 4 C 3 H 2 Tetrane. Tetrvl.' Tetrene. Tetrem 1. Tetrine. Tetrone. C 4 H 10 C/H 9 C 4 H S C 4 H' 7 C 4 H 6 C 4 H 4 Pentane. Pentyl. Pent-ene. Pentenvl. Pentone. C 5 H 12 C,H 1X C 5 K 10 c 5 h; C 5 H 8 C 5 H 6 Hexane. Hexyl. Hexene. Hexenyl. Hexine. Hexone, C 6 H 14 C6-H-13 C 6 H 12 C 6 Hn C 6 H 10 C 6 H S etc. etc. etc. etc. etc. Tritune. Tetrune. C 4 H 2 Pen tune. C 5 H 4 Hexune. C 6 H 6 IO 138 ESSENTIALS OF CHEMISTRY. The nomenclature is systematic, but has never been fully adopted. The root of each name is from a Greek numeral and indicates its position in homologous series, while the final vowel indicates its position in isologous series. By successive abstrac- tions of an atom of hydrogen are formed several series of organic radicles, the valences of which depend on the number of atoms abstracted, and thus increase in isologous series. They are given the general termination of "-yl." Being positive, these radicles combine with negative radicles, just as do K, Na or NH 4 , and form analogous compounds. Methane Series, sometimes called the Paraffins {parum, too little and affinis, having affinity) on account of their lack of affin- ity for chemical reagents, is a class of hydrocarbons derived in homologous series from CH 4 . Being fully saturated, they are very stable and indifferent to chemical reagents, unaffected usu- ally by either acids or alkalies. The natural, crude Petroleum is a mixture of mainly these various hydrocarbons 30S as far down as the sixteenth (C 16 H 34 ). On account of their boiling-points vary- ing with their molecular weights, they can be more or less com- pletely separated by fractiomal distillation, those having the light- est molecules passing over first. As all the lighter ones are liable to give off vapors that when mixed with air are explosive, it is forbidden in most states to sell, for use in ordinary lamps, an oil that " flashes" below 100 F., or itself ignites below 300 F. Of 308 Cymogene, boils about 32 F.; used in ice-machines. Rhigolene, boils about 65 F.; as a spray for local anaesthesia. Petroleum Ether, boils about ioo° F.; used as a solvent and for "air-gas." Gasolene, boils about 120 F; used as a solvent and for " air-gas." Naphtha, A, B and C, boils 180 to 3CO L ' F.; used as a solvent for fats, etc. Benzine, boils about 150 F. ; used as solvent in varnishes and paints. Kerosene, boils about 350° F. ; used in ordinary lamps. Mineral Sperm oil, boils about 425 F.; used for lubricating machinery. Lubricating oil, boils about 575° F.; used for lubricating machinery. Petrolatum, U. S. P., used in ointments, etc. Parafnne, used in candles. * 09 Into a large test-tube pour about 20 Cc. of cheap kerosene, insert a ther- mometer and a bent glass tube. Apply a heat so gently that the temperature rises only about a degree a minute. At frequent intervals blow through the glass tube and make a foam on the surface of the oil and apply a flame to the mouth of the test-tube. When the flame flashes down the tube note the read- ing of the thermometer and regard that as the " flashing-point." PART II. — ORGANIC CHEMISTRY. I 39 the commercially separated products the Pharmacopoeia recog- nizes as officinal Benzine or petroleum ether, a colorless, volatile liquid ; Petrolatum Liquidum, a tasteless, oily liquid, called also albolene ; Petrolatum Molle, the soft vaseline, and Petrolatum Spissum, the harder vaseline. Methane (CH 4 ) is a light, colorless gas, occurring in illumi- nating gas formed from the destructive distillation of coal : in coal mines as "fire damp," where it often causes frightful explo- sions ; from decomposition of vegetable matter under water, where as "marsh-gas" it may be seen bubbling up, especially when the mud is stirred ; in natural gas, of which it constitutes over 90 per cent. CH 4 is the starting point for the synthetical production of many other organic compounds, and may itself be made artificially from ethine (acetylene), which is made from the minerals, calcium carbide and water. 810 Ethane (C 2 H 6 ), Tritane or propane (C 3 H 8 ), and Tetrane or butane (C 4 H 10 ), escape when crude petroleum is heated. These gases are collected, condensed into a liquid, and sold as cymo- gene for ice making. Methene Series. — These were formerly called " olefins," be- cause the first member, Ethene (C 2 H 4 ), happens to form an oily- liquid with chlorine, and was named "defiant gas." Ethene is formed in the destructive distillation of coal, and is the most valuable constituent of illuminating gas, where it is called "heavy carburetted hydrogen." Being unsaturated the olefins are readily attacked by reagents, especially the acids. Ethine Series. — These too are unsaturated , they act as bivalent or quadrivalent radicles. Ethine or acetylene (C 2 H 2 ) is the most important member and enjoys the distinction of being one of the few, if not the only, hydrocarbon made by the direct union of its elements. It may be produced by the electric arc between carbons in an atmosphere 310 Heat in a test-tube a mixture of 4 parts cf sodium acetate, 4 parts of XaHO and 6 parts of lime; collect the gas; it is methane. 140 ESSENTIALS OF CHEMISTRY. of hydrogen. It is now made industrially as an illuminant, from calcium carbide 311 and water ; thus, CaC 2 f 2H 2 = Ca(HO) 2 + C 2 H 2 . It is very rich in carbon (92.3 per cent.) and burns with a very pure white flame of dazzling brilliancy. Tritone Series or Terpenes. These- are unsaturated and either univalent or bivalent and combine readily with the nega- tive radicals. The series begins with Tritone (C 3 H 2 ), but it is the eighth member, Decone or Terpene (C 10 H 16 ) that possesses most medical interest, as this formula represents the composition (iso- meric) of most of the volatile or essential oils, such as those of lemon, orange, cloves, pepper, lavender, bergamot, etc. Volatile oils are found in plants, especially in the flowers, of which they are usually the odorous essences (hence called also essential oils). They are obtained by distillation, are very slightly soluble in water (aquae), but quite soluble in alcohol (spiritus). A cologne is an alcoholic solution of an assortment of volatile oils. Turpentine (oleum terebinthinae, U. S. P. obtained from Pinus Australis) is the most important of the volatile oils ; obtained as a resinous juice from various coniferae, and may be taken as a type of the class. It is a thin colorless liquid, a valuable solvent of oils and resins ; absorbs oxygen and stores it up as ozone, gaining thereby oxidizing, antiseptic and disinfectant properties. By the action of concentrated sulphuric acid, turpentine is changed into terebene (Ci H 16 ), a valuable remedy for bronchitis and flatulence. Resins and Camphors. On exposure to air the terpenes oxidize with the production of resins and camphors, whose for- mula is C 10 H 16 O. Resins are a numerous class, many of which are true acids or mixtures of acids. They are soluble in alcohol but insoluble in water except by the intervention of an alkali with which they will 311 Calcium Carbide, CaC 2 . The manufacture of this recently discovered article is remarkably simple and cheap. When a mixture of lime and coke are placed in the electric furnace they fuse into a dark gray crystalline mass on which the heat has no further effect. This calcium carbide is packed for the market in sealed cans to protect it from the water of the air. PART II. ORGANIC CHEMISTRY. 141 unite to form soluble soaps. The official resin (resina, U. S. P.) is formed by the oxidation of turpentine as it exudes from the pine trees. Solutions of shellac, mastic, copal and others are used as var- nishes. In the natural state, resins are usually mixed with other substances. Mixed with volatile oils they form oleo- resins and balsams, e. g., benzoin, tolu and balsam of Peru ; and with gums, gum resins, e. g., ammoniac, myrrh and asafoetida. Camphors, sometimes called stearoptens. — These are white, crystalline, volatile solids of an agreeable, pungent odor ; slightly soluble in water (aqua camphorae), freely soluble in alcohol (tinctura camphorae) ether and oils. Common Camphor is derived from the leaves and branches of the camphor laurel of China and Japan. It is much used ; inter- nally, as a stimulant, diaphoretic, carminative and expectorant, and externally, as an antiseptic and analgesic. Monobromated Camphor, C 10 H 15 BrO, is made by adding bromine to a solution of camphor in chloroform, the bromine displacing one atom of hydrogen. It is more sedative than ordinary camphor. Menthol is the camphor of oil of peppermint, and has its odor. It is much more analgesic than common camphor. Thymol is the camphor of oil of thyme and of horsemint. It is a stronger antiseptic than carbolic acid, and withal has a pleasant odor. Caoutchouc or India-rubber (Elastica U. S. P.), and gutta- percha. These are terpenes, which, insoluble in water, occur suspended in the milky juice of certain tropical plants. Caout- chouc is soft and elastic ; gutta-percha is hard and brittle. Both can be vulcanized (combined with sulphur), the hardness, etc., depending on the amount of sulphur and heat used ; so that many valuable articles are made from them. Caoutchouc dissolves in petroleum-ether and carbon disulphide \ gutta-percha dissolves best in chloroform (liquor gutta-perchae). Benzene Series. So named because they are all derived from 142 ESSENTIALS OF CHEMISTRY. Benzene (Hexune) C 6 H 6 , and are also called " aromatic" because of their aromatic odor and taste. Benzene™ must not be confounded with benzine, one of the petroleum products. Benzene is distilled from coal-tar and is a colorless, volatile liquid of a peculiar odor, and a valuable solvent. It is especially interesting to the chemist for the great number and diversity of its derivatives. Treated with strong nitric acid, it yields Nitrobenzene or oil of mirbane™ a very poisonous sub- stance used as a cheap perfume, especially in soaps. Toluene (heptune), C 7 H 8 , is another member of -this series, but of little medical interest, except sometimes used locally in diph- theria. Naphthalene is the so-called " coal-tar camphor," and is em- ployed in the form of moth-balls. Halogen Derivatives of the Hydrocarbons. The hydrogen in the hydrocarbons is replaced by the halogens, viz., by chlorine, bromine, and iodine, forming halogen derivatives. They are for the most part colorless, ethereal smelling liquids, insoluble in water. If nascent hydrogen is allowed to act upon these deriva- tives, it combines with the halogen atom and returns the deriva- tives to their previous state, thus, CHC1 3 + 3H 2 = CH 4 -f 3HCI. Chloroform (trichlormethane) CHC1 3 is made 314 by distilling a strong solution of chlorinated lime and ordinary alcohol. Of late it is being manufactured more economically by a patented process from acetone, a bi-product in certain manufactures. Chloroform is a colorless, volatile liquid of a sweetish taste and an agreeable, ethereal odor. It is heavier than water and does not dissolve in it, but soluble in alcohol and ether. It is a sol- vent for phosphorus, iodine, india-rubber, the alkaloids, and 312 Benzene. Heat a mixture of dry benzoic acid and quicklime and pass the vapor of the benzene evolved into a test-tube set in ice, Fig. 26. 313 Nitrobenzene. Mix two parts of H 2 S0 4 and one of HN0 3 : let cool. Add benzene a drop at a time, shaking and cooling each time until I or 2 Cc. are added. Then pour into water and note the " essence of mirbane " sinking as a brownish-yellow oil to the bottom. iU Chloroform. In the apparatus shown in Fig. 26 distil 5 Gm. of chloral covered with KHO solution, and examine distillate for chloroform. PART n. — ORGANIC CHEMISTRY. 1 43 many other substances. Its vapor is heavier than air, but is not easily ignited. Yet it should not be administered it too near a flame, for fear of the poisonous, irritating fumes from its decom- position. Chloroform is sometimes given by the stomach as a sedative but most frequently administered by inhalation as an anaesthetic, for which purpose it should be of undoubted purity. Test of Purity : — Pure chloroform is not colored by an equal volume of pure sulphuric acid ; the specific gravity should not be below 1.480. If chloroform be taken by the stomach, it being almost insolu- ble, is absorbed very slowly, and its principal action is the local irritation of the mucous surfaces. Recovery has followed a dose of four ounces, and death has been caused by one drachm taken into the stomach. The vapor acts more energetically and seems to owe its potency for evil to its paralyzing influence on the nerve centers, especially these of the heart. For this reason chloroform should never be administered except by a capable physician, It should be well diluted with atmospheric air. However, death has occurred from the inhalation of moderate quantities of chloroform properly diluted and at the hands of careful physicians, and where the autopsy revealed no heart lesion. There is no chemical anti- dote for chloroform. When it has been swallowed evacuate the stomach ; when inhaled, lower the head, give fresh air, employ artificial respiration, apply the induced current, and administer hypodermic injections of strychnine and whiskey. Chloroform should be kept in dark amber-colored bottles, and carefully corked to prevent evaporation. In cases of intentional poisoning by chloroform the odor of the chemical is usually sufficient for recognition. Bromoform — CHBr b — is a colorless liquid of agreeable odor, formed by the action of bromine and potassium hydrate upon al- cohol. It has been used as an anaesthetic, the advantage claimed being that both pulse and respiration remain about normal, even in prolonged narcosis. It is a valuable sedative in whooping 144 ESSENTIALS OF CHEMISTRY. cough. It is, however, poisonous when taken internally in large amounts. In the case of two children, one four, the other four and one-half years old, recovery is reported after the ingestion of about 20 grains. In both cases ether and camphor were injected hypodermically to antagonize the bromoform. Iodoform — CHI 3 — is formed by the action of iodine and potas- sium hydrate on ordinary alcohol. It is a yellow, crystalline body, soluble in alcohol and ether, but insoluble in water. In spite of its disagreeable odor it is much used for its antiseptic effects — effects due not to the iodoform as such, but to traces of iodine liberated in its decomposition by the living tissues. The other therapeutic properties of iodoform are alterative, anaesthetic and anti-tubercular. Alcohols and their Derivatives. An alcohol is generally regarded as the hydrate of a hydrocar- bon radical since its formula always has a hydrocarbon radical at its positive end, and the radical HO at the negative end. It might be regarded as formed by substituting the radical HO for an atom of hydrogen in the molecule of a saturated hydrocarbon : and again from H 2 in which one atom of hydrogen is replaced by a hydrocarbon radical. Methyl Series. — The alcohols of most interest to the physician are those of the Methyl series ot hydrocarbon radicals. They are often called the monatomic alcohols because all this series of radi- cals are univalent (monad.) The following table shows a few of them and their derivatives : Examples of Com- pound Ethers. Radicals. Alcohols (Hydrates). Ethers (Oxides) . Alde- hydes. Acids. Nitrates. Sulphates. Methyl, CH 3 CH 3 HO (CH 3 ) 2 CH 3 N0 3 (CH,)oS0 4 CHoO CH 2 2 Ethyl, C,H, C 2 H 5 HO (C„H 5 ) 2 C,H 5 N0 3 (C 2 H 5 )„S0 4 CoH 4 CoH 4 Oo Propyl, C 3 H 7 C3H.HO (C 3 H 7 ) 2 C 3 H 7 N0 3 (C 3 H 7 ) 2 S0 4 C 3 H«0 C 3 H G 2 Butyl, C 4 H 9 C 4 H 9 HO (C 4 H 9 ) 2 C 4 H 9 N0 3 (C 4 H 9 ) 2 S0 4 C 4 H s O C 4 H 8 2 Amyl. C 5 H tl C 5 H n HO (C B H 1]L ) 2 CsH^NOg (C 5 H X1 ) 2 S0 4 C B H 10 C 5 H 10 O 2 Hexyl,C 6 H 13 C 6 H 13 HO (C 6 H 13 ) 2 C 6 H 13 N0 3 (C 6 H 13 ) 2 S0 4 C 6 H 12 ^6^-1 2^2 etc. etc. etc. etc. etc. etc. etc. PART II. — ORGANIC CHEMISTRY. 1 45 In the formation of these compounds the starting point is not the radicals, but their hydrates, the alcohols. When an alcohol is oxidized with a limited supply of oxygen, two atoms of hydro- gen are removed and no oxygen is added. This forms the alde- hyde, thus : Methyl Methyl Alcohol. Aldehyde. CH3HO + O = CH 2 + H 2 0. If there is a full oxidation, an atom of oxygen takes the place of the two atoms of hydrogen removed, and forms the corresponding acid, as — Methyl Formic Alcohol. Acid. CH 3 HO + 2 = CH 2 2 + H 2 0. In the formation of aldehydes and acids the radical supplies part of the hydrogen removed and loses its identity. As part of the hydrogen in an acid forms the positive radical it is written first ; e. g., formic acid is written HCH0 2 , (rational formula) in- stead of CH 2 (X (empirical formula). The various other com- pounds of these radicles are called ethers ; the oxides being called simple ethers, the others compound ethers. They are generally formed by treating the appropriate alcohol with the appropriate acid. A Ketone is an organic compound consisting of the unsaturated radicle "CO " united to two univalent radicles, as in (CH 3 ) 2 CO, dimethylketone, commonly called aceto?ie. Methyl Alcohol — (CH 3 HO), the so-called wood spirit, wood naphtha, wood alcohol, or pyroligneous spirit, is obtained from the destructive distillation of wood; it does not exist in nature. When pure it resembles ordinary alcohol in its properties and physiological action, but the commercial article has a disagreeable odor and taste from the presence of tarry matters, etc. It is not used in medicine, but is employed widely in the arts as a substi- tute for ordinary alcohol, which, though cheaper to manufacture, cannot be sold as cheaply because of the tax imposed on alcoholic 146 ESSENTIALS OF CHEMISTRY. beverages. In England ordinary alcohol is relieved of this tax and made available to the arts by mixing with it 10 per cent, of commercial methylic alcohol, which makes it unfit to drink. Ethyl alcohol, C 2 H 5 HO, also called spirits of wine, vinic alco- hol and alcohol, is obtained in the spirituous fermentation of sev- eral varieties of sugar, such as grape-sugar, maltose, etc. Glucose. Alcohol. Carbon dioxide. C 6 H 12 6 - 2C 2 H 5 HO + 2C0 2 . Liquids (wines, etc.), containing alcohol, have been known and used as beverages from the remotest antiquity. From these the alcohol is separated by distillation, for being more volatile than the water it passes over first. 815 Commercial alcohol always contains water, and when pure, or " absolute " alco- hol is required, the commercial article is mixed with some sub- stance, which is very avid of water (as quick lime), and then again distilled. Ethyl alcohol may also be obtained experimentally from ethyl chloride (C 2 H 5 C1), bromide (C 2 H 5 Br), or iodide (C 2 H 5 I), by replacing the halogen with HO. This is best accomplished by the agency of freshly precipitated silver oxide and water (prac- tically silver hydrate) in the presence of heat, thus : C 2 H 5 Br + AgHO = C 2 H 5 HO + AgBr. Alcohol is a light, colorless liquid of a pleasant, pungent odor and burning taste. It has great affinity for water, which fact probably accounts for its preserving animal tissues and coagulat- ing the albuminoids. At minus 194 F. it is a thick liquid and at minus 266 F. a solid white mass. It boils at 173. 6° F. Test for Parity. — Absolute alcohol is soluble without turbidity in a small amount of benzene. If 3 per cent, or of more water is present in the alcohol cloudiness appears on adding the benzene. Analyses for traces of alcohol in a solution are best made by oxidizing the alcohol into an aldehyde, or by converting the alco- 815 Alcohol. Distil some wine in apparatus shown in Fig. 26 [side neck test-tube distilling apparatus] and test distillate for alcohol by odor, taste and iodoform test. PART II. ORGANIC CHEMISTRY. 1 47 hol, by means of dilute KHO (or NaHO) and iodine, into iodo- form." 16 It is largely used in the arts and in pharmacy, principally as a solvent ; and also in the manufacture of various substances, as vinegar, chloral, chloroform, iodoform, ether, etc. ; as a fuel when a hot and smokeless flame is needed and as a menstruum in the preparation of tinctures and spirits. Alcoholic solutions of fixed medicinal substances are called " tinctures ;" those of vola- tile principles, " spirits." Alcohol is used in many forms and of various degrees of concentration. Absolute alcohol is rarely em- ployed, except in chemical analyses. Alcohol, U. S. P., is the ordinary rectified spirit, and contains 91 per cent, of alcohol. Alcohol dilulum, U. S. P., diluted alcohol, is made by mixing water and alcohol equal parts. Spiritus frumenti, U. S. P., whisky, and spiritus vini gallici, U. S. P., brandy, are obtained by distillation ; the former from fermented grain, and the latter from fermented grape juice. They contain about 50 per cent, of alcohol. Both are colored by the addition of caramel (burnt sugar). Their flavor is due to small quantities of other alcohols, produced in the fermentation, and to certain ethers formed from these alcohols, especially as the liquor " ages." A large class of alcoholic beverages are made by fermenting various liquids con- taining sugar or some substance capable of conversion into sugar. Beer, ale and porter are infusions of malted grain fermented and flavored with hops. They, therefore, contain the soluble constituents of the grain. Their alcoholic strength is about 5 per cent. Wines are prepared by allowing grape juice to ferment. Various wines are used but the pharmacopoeia recognizes only two classes, White and Red, each with an alcoholic strength of 10 to 14 per cent. Cider is the fermented juice of the apple and contains about 5 per cent, of alcohol. It is very prone to acetous fermentation and liable to produce colic and diarrhoea. 316 Warm the solution supposed to contain alcohol; add a few scales of iodine, and then caustic potash until the color is discharged. On cooling, yellow scales of iodoform are deposited. 148 ESSENTIALS OF CHEMISTRY. Alcohol when concentrated abstracts water from the tissues and coagulates their albuminoid constituents ; and is a poison. In full doses (always best with food) alcoholic liquors produce a sense of warmth in the stomach, general comfort and exhilaration followed by incoherence of ideas and impairment of muscular co- ordination. Taken habitually, in any of its forms, it impairs the mental and moral force of its victim, and produces in the various organs, especially the liver and kidneys, the degenerative changes charac- teristic of " chronic alcoholism." It should never be taken in health, but as a medicine it is the most valuable of stimulants. In cases of acute poisoning by alcohol, the stomach and bladder should be evacuated and the depression (coma) counteracted by strong coffee, the cold douche, and other stimulants. Triiyl (propyl) alcohol and tetryl (butyl) alcohol need only to be mentioned here ; in fact, the only other alcohol of this series possessing medical interest is pentyl alcohol. Amyl alcohol, pentyl alcohol, C 5 H n HO,'/z^/ oil, This is a heavy liquid, soluble in alcohol but not in water, hence incor- rectly called an oil. It is produced in fermentation of grain, potatoes and other starchy substances, and is the most deleterious impurity in common whisky, before it has undergone the refining process (rectification). It has a penetrating, disagreeable odor, resembling that of mean whisky. Although not fragrant itself, its ethers, when dissolved in ethyl alcohol, have the taste and odors of various fruits, and are used in the preparation of artificial essences. 317 Sulphur alcohols or mercaptans. It was noted in discussing the sulphur group (inorganic) that sulphur had the faculty, in a marked degree, of playing the same roles as oxygen and forming analo- gous compounds. The sulphur alcohols and ethers are strong smelling, irritating bodies, some of which are derived from ani- ;sl7 To a half drachm of fusel oil in a test-tube add some sodium acetate, and a few drops of sulphuric acid. Warm the mixture, and the pentyl (amyl) acetate, "essence of pear" will be recognized by its odor. PART II. — ORGANIC CHEMISTRY. 1 49 mals and plants, rt (A O O a . s rt 5 2 «* r-£ _5 TJ -m 3J o r ° R^, « X, ~-i yj m v "; ►3 O PQ> 3 § a V4 (-i )-• o rs 5 -« w ! 11 l 3 c3 .s S3 *S tm pqCM vO 00 vO LO00 w fit! . cS cS O 43 So 5? u coo 00 oco -+ «C QO i-( — - l_i_i hU hh ^G hh 3-1 Juud 9 u^ u x a -1 ffi K ffi ffi'ffi ffi ffi ffi ffi K uuuuuuWuu s a V « s o .id 43 ^ P-44 Ph g 5-. fcj »-. cs ^T3 _CJ '3 """ s a o 5 PART II. — ORGANIC CHEMISTRY. 157 the alkali-metals is due to the precipitation of insoluble soaps or plasters. Soaps are made by the saponification of a fat with a caustic alkali. For example : — Stearine. Sodium Stearate. Glycerine. (C 3 H 5 ) (C 18 H 35 2 ) 3 + 3NaHO == 3 XaC 18 H 35 2 + C 3 H 5 (HO) 3 . When soap dissolves in cold water, it probably decomposes into an acid salt which makes the soapsuds 3 " 1 and a small quantity of free alkali which does the cleaning by dissolving and, to some extent, by emulsifying by the fats. Methene Series. This series of radicles is bivalent, so that their alcohols or acids are diatomic or dibasic. Their alcohols are unimportant except, perhaps, ethene alcohol or glycol C 2 H 4 (HO) 2 , which though of some chemical interest, has no practical application in medicine. Most of the acids of this series are Diatomic or Dibasic, Oxalic Acil, H 2 C 2 4 , occurs in many plants, mainly as potas- sium binoxalate, especially in the sorrel (oxalis) grasses, and in the animal economy appearing in the urine, occasionally forming calculi of calcium oxalate. It is largely and cheaply made from sugar or saw-dust by the oxidizing action of nitric acid or caustic alkalies. It is a crystalline solid and closely resembles Epsom salts, for which it is sometimes taken by mistake. It is a power- ful irritant poison \ and being cheap and largely used for removing ink- stains, cleaning copper, etc., poisoning by oxalic acid is by no means rare. Its best antidote is chalk or some ether compound of calcium, with which it forms a very insoluble compound. Its best test is some calcium solution, as chloride, forming a white precipitate insoluble in acetic but soluble in hydrochloric acid. 333 HgCl 2 and note white precipitate of mercuric soap. 334 Lather. Pour 1 Cc. of soap solution into some soft water in a test- tube; shake and note lather. 33i Lime soap. Next add CaCl 2 and shake; note no lather, but a curd of lime soap. 336 Softening hard water. To a portion of soap solution add XaXO s , and then CaCl 2 . Shake and note that CaC0 3 is precipitated and a lather forms. 158 ESSENTIALS OF CHEMISTRY. Lactic Acid, H 2 C 3 H 4 Q3 {lactis, of milk) . — This is the acid of sour milk, where it is formed by the fermentation of the sugar of milk through the agency of the casein. It is also formed in the body by the decomposition of glucose, thus : — C 6 H 12 6 — 2H 2 C 3 H 4 3 . It is a syrupy liquid, of a very sour taste. Succinic Acid, H 2 QH 6 4 , is found in amber (succinum), lignite, resins, and in certain animal fluids. When fats are oxidized with nitric acid, succinic acid is formed. It is now usually made by fermenting malic acid. Colorless, odorless prisms, soluble and with an acrid taste ; used as an anti-spasmodic and diuretic. Malic Acid, H 2 C 4 H 4 5 (malum, an apple\ exists in many sour fruits and plants, as apples, cherries and garden rhubarb, but may be made artificially from succinic acid. The acid and its salts are mostly soluble. Tartaric Acid, H 2 C 4 H 4 6 , or H 2 T. — Tartrates exist in the juices of many fruits. Grape juice contains much acid tartrate of potas- sium (KHT), which, being very insoluble in an alcoholic men- struum, is precipitated on the sides of the cask whenever the wine ferments. This forms argol, the principal source of cream of tar- tar and tartaric acid. Tartaric acid forms colorless crystals, very soluble, and of a sharp, agreeable, sour taste. It is used in the manufacture of baking powders, in Seidlitz powder, and in effervescent drinks. Citric Acid is closely related to tartaric acid in its sources pro- perties and uses, but it is triatomic or tribasic. It exists in the juices of many fruits, especially the lemon. Forms colorless crys- tals which are very soluble, and possess a sour taste. Many of its salts are used in medicine. Methenyl Series. — These are trivalent radicles, and form tria- tomic alcohols and acids. The most important member of the series is tritenyl, C 3 H 5 , sometimes called propenyl, and more commonly glyceryl. Its alcohol is PART II. ORGANIC CHEMISTRY. 159 Glycerine, ox glycerol, C 3 H 5 (HO) 3 . Being made from fats, in the manufacture of soaps and candles, it has been called (Scheele, 1779) "the sweet principle of fats ;" but it has no chemical anal- ogy with those ethers, since it is the hydrate of tritenyl, and therefore an alcohol. Glycerine is produced in the saponification of fats, whereby the fats are broken up into fat acids and glycerol, thus : Tritenyl Stearate. Sodium Stearate. Glycerol. (QH 5 ) (C 18 H 82 2 )s + 3NaHO = 3 NaC 18 H S5 2 + C 3 H 5 (HOj 3 . It is a colorless, odorless, sweet, viscid liquid, avid of water, neu- tral in reaction, soluble in all proportions in water and in alcohol, and a solvent of a great many mineral and organic substances, the solutions being called glycerites. On account of its hygro- scopic property, it has a wide scope of usefulness in therapeutics as a laxative, as a depletant and emollient. Tritenyl Nitrate, C 3 H 5 (N0 3 ) 3 , usually called nitroglycerine. When glycerine is added drop by drop to a mixture of equal volumes of strong nitric and sulphuric acid, until the glycerine no longer dissolves, and the liquid is then poured into water, nitroglycerine separates as a colorless, heavy, oily-looking sub- stance of a peculiar odor and sweet taste. It is a powerful ex- plosive, and to prevent its accidental explosion on percussion, it is usually mixed with some inert dry powder, as silica, sawdust or powdered charcoal, and sold as dynamite or giant powder. Ni- troglycerine is much used in medicine (dose, t -J-q gr.) as a pow- erful and quick heart stimulant. Phenol, phenyl alcohol (hydroxybenzene), C 6 H 5 HO, is gener- ally called Carbolic Acid, also phenic, or phenylic, acid ; called an acid because it combines with bases to form salts, the carbo- lates, or phenates. It belongs in the class of benzene, or aromatic alcohols. Carbolic acid is formed in a number of reactions, but the com- mercial article is obtained exclusively from coal tar. It has a strong, disagreeable odor; stains skin and mucous membranes white by coagulating their albumin ; and is a corrosive poison. l6o ESSENTIALS OF CHEMISTRY. Care should be exercised in its local application over large sur- faces, even in dilute solution, especially on infants, as poisoning may occur by absorption. Injections of carbolic acid are used to abdrt boils and carbuncles and also in the treatment of hemor- rhoids ; and many fatalities are recorded. Antidote : any soluble sulphate as MgS0 4 , then albumin (milk, egg, etc.) in abundance; but the most efficient antidote has recently been found to be al- cohol. For burns by carbolic acid, glycerine is an excellent remedy. Sulphocarbolates. Carbolic acid will unite with sulphuric acid and form sulphocarbolic acid, C 6 H 5 HS0 4 (phenyl-bisulphate) from which are formed the sulphocarbolates, a class of astringent, antiseptic salts, much used in medicine. Resorcin, C 6 H 4 (HO) 2 , closely related to phenol, but a stronger antiseptic and much less poisonous. It is obtained from various resins or prepared from benzene. Creasoteis a complex mixture obtained from wood-tar ; closely allied to carbolic acid in its properties and uses, but may be readily distinguished from it by being insoluble in glycerine. The best creosote is obtained from beech-wood. It is a colorless, or faintly yellow, oily liquid, of a characteristic odor and caustic, burning taste. It is at present a popular remedy in pulmonary tuberculosis, and has long been used as a sedative and astringent in vomiting and diarrhoea, and as a local anaesthetic. Large doses are poisonous and the antidote is the same as for carbolic acid. Guaiacol is a constituent of creasote and is prepared from it by fractional distillation. It is a colorless, limpid, oily liquid of a characteristic, aromatic odor and taste; extensively used in tuberculosis, both pulmonary and intestinal. Guaiacol carbonate is better adapted for internal medication, since it is neutral, odorless and tasteless, and therefore less irritating. Dose, 2 to 5 grains gradually increased to a drachm or more a day. Both guaiacol and its carbonate must be given for quite a time in tuberculosis before their full effects are obtained. PART II. — ORGANIC CHEMISTRY. l6l Cresol occurs in several modifications in coal-tar, creasote, phenol, etc., and is also made artificially. Though more power- fully antiseptic than phenol, it is much less caustic and poisonous. Under the trade names of " creolin," "lysol," etc., it is sold for domestic use as an antiseptic. Salol is phenyl salicylate, C 6 H 5 C 7 H 5 3 , and is an ether. It is a white powder, tasteless and insoluble in neutral and acid media, but in the presence of the fixed alkalies it breaks up into phenol aud a salicylate. 337 When taken, it passes through the stomach unchanged, to be decomposed and made available in the bile and intestines ; hence used as an intestinal antiseptic and antirheu- matic. Salophen resembles salol in its physical, chemical and physio- logical properties and therapeutic uses. Saccharin is a white powder, slightly soluble in water, but at least 200 times as sweet as sugar, from which its name is derived. It has no chemical analogy to the sugars, but is closely related to the phenols. It is used as a substitute for sugar in sweetening, but has the disadvantage of disturbing digestion. Benzoic Acid. — HC 7 H 5 2 , occurs in benzoin, from which it may be sublimed in silky needles slightly soluble in water and of a pleasant, balsamic odor/ 38 Much is now made from hippuric acid, obtained from the urine of herbivorous animals ; but such benzoic acid has a urinous odor. It is made industrially by the oxidation of benzene. Is given in doses of 15 grains, as an expectorant and as an antiseptic in cystitis, its presence in the urine destroying the germs of the alkaline fermentation. This and the following acids belong the class of " Aromatic Acids." Picric or Carbazotic Acid is trinitro-phenol, C 6 H 2 (N0 2 ) 3 HO, u e. 9 phenol in which three molecules of (N0 2 ) have replaced 337 Salol 7 est, U. S. P. Warm 1 Grn. of salol with liq. potassse enough to dissolve it; supersaturate with HC1, and note the precipitation of silky needles of salicylic acid, and the odor of phenol. 338 Benzoic acid. Warm a small lump of benzoin in a test-tube, and note sublimate (needles) of benzoic acid. 1 62 ESSENTIALS OF CHEMISTRY. three atoms of hydrogen ; and is made by treating phenol with nitric acid. 339 It crystallizes in a yellow powder slightly soluble in water and is much used as a dye. If warmed carefully it may be sublimed, but if heated suddenly, explodes with violence. It behaves as a monobasic acid, and its salts are mostly solid yellow, crystalline bodies, some of which are: used in medicine. Vast quantities are now used in the manufacture of explosives, as " lyddite." It may be recognized by its bitter taste and yellow color ; by its coagulating albumin and peptone ; and by a blood- red with glucose and a dilute alkali. Salicylic Acid (monobasic). — Formerly prepared from salicin, but now made by a patented process from carbolic acid. A very pure acid is obtained from oil of wintergreen, which consists mainly of methyl-salicylate. 340 Salicylic acid is almost insoluble in cold water ; hence the sodium salicylate is usually prescribed, which is also less irritat- ing, though not so bland as the corresponding strontium salt. It has antiseptic, antipyretic and antirheumatic properties and a wide range of usefulness as an application in skin diseases. Test : intense violet with a ferric salt. Gallic Acid. — When galls are moistened and exposed to the action of the atmosphere, the tannin they contain is converted into gallic acid. It resembles tannin but does not precipitate gelatin. So the gradual conversion of tannin into gallic acid inci- dental to leather manufacture is a source of constant loss to the tanners, since gallic acid does not tan. Pyrogallic Acid sublimes as white, feathery crystals when gallic acid is heated. Combined with an alkali, it is used in gas-analysis 389 pi cr i c acid. Mix 5 Cc. of dilute nitric acid and 2 Cc. of carbolic acid and let it cool; boil with 10 Cc. of strong HN0 3 for several minutes, adding more HN0 3 , drop by drop, as long as carbolic acid floats on top. Finally cast into 25 Cc. of cold water. Note the yellow crystals of picric acid, and that when they are dried and dropped into a fire they explode. 3,0 To 1 Cc. of oil of wintergreen in a test-tube add 5 Cc. of liq. potassae; heat until saponification and solution is complete; add HC1 and note the mass of silky, white crystals of salicylic acid. PART II. — ORGANIC CHEMISTRY. 1 63 to absorb oxygen ; in photography as a deoxidizer ; externally in psoriasis and other skin diseases ; and also as hair-dye. Test : a blue with ferrous and a red with ferric solutions. The Carbohydrates. These substances are closely related to the alcohols, being prob- ably aldehydes. They are called " carbohydrates " because they contain carbon (six or twelve atoms) and the hydrogen and oxy- gen they contain are in the exact proportion to form water. They constitute the bulk of all plants. They are divided into three groups : Amyloses, C 6 H 10 O 5 ; saccharoses, C 12 H 22 0n, and glucoses, C 6 H 12 6 . AMYLOSES, C 6 H 10 O 5 . This class includes cellulose, gums, starch, dextrin and glycogen. Cellulose (cellulin, lignin) forms the cell-walls and tissues of plants, and is a distinctive characteristic of the vegetable king- dom. Woody fibre, cotton, linen and unsized paper are almost pure cellulose. It is insoluble in almost every 341 reagent except a solution of cupric oxide in ammonia-water. 3 * 5 Acids precipi- tate it as a white mass. 346 Unsized paper dipped into moderately strong sulphuric acid, washed and dried, has its fibres aggluti- nated, loses its porosity, becomes very tough, and is sold as arti- ficial parchment for dialyzers, diplomas, etc. Nitrocellulose or " gun-cotton," a powerful explosive, is cotton that has been dipped into a mixture of nitric and sulphuric acids, and then 841 Cellulose. Put bits of filter paper in three test-tubes. 342 To one add water and boil; no effect. 848 To the second add KHO solution; the fibres swell and become gelatinous. 844 To the third add H 2 S0 4 , and note that it turns black. 345 To the fourth add cupric hydrate solution (made by dissolving Cu(HO) 2 in aqua ammonise), and note that the paper is dissolved. 8,6 To the solution add HC1 until the ammonia is neutralized and the deep blue color discharged, and note that the cellulose is precipitated as a gelatinous mass. 3i7 Artificial parchment. Immerse a sheet of filter paper in strong H 2 S0 4 for about 15 seconds; wash thoroughly and dry. Note that the fibres have become agglutinated and the paper made stronger. 164 ESSENTIALS OF CHEMISTRY. washed and dried. Mixed with camphor and compressed it is celluloid. Its solution in ether, or in a mixture of alcohol and ether, is collodion™ The " flexible collodion" contains a little turpentine and castor oil ; the " styptic collodion " contains 20 per cent, of tannin. Gums are amorphous, odorless, tasteless, sticky substances ; found in many plants ; soluble in water but insoluble in alcohol. Some, as gum-arabic, make clear solutions (mucilages) with water, while others, like gum-tragacanth, only swell up and form a paste. Starch (amylum), the most important member of the carbo- hydrates, and a valuable food, is found in the roots, 351 stems or seeds 349 of all plants. Starch is a white powder consisting of granules formed of concentric layers, like an onion. 351 These granules all have a similar appearance, yet those from different kinds of plants differ enough to enable one by microscopic examination to determine the source of any starch (Fig. 39). When starch is boiled the granules swell and burst, casting starch into the water, appearing to dissolve 353 and forming mucilage of 348 Collodion. Immerse a pledget of absorbent cotton 15 minutes in a mixt- ure of 2 parts of strong H 2 S0 4 and 4 of HN0 3 ; wash thoroughly and dry. Note that it burns with a flash, and is soluble in a mixture of ether and alcohol. 349 Starch. Grind some rice in a mortar, adding water from time to time, and strain the milky fluid through a cloth. Separate the starch by subsidence and decantation, and finally dry it on filter paper. 350 Granules. Mount a drop of the milky fluid above mentioned under a cover glass on a slide for examination later, when the peculiar structure of the granules can be noted. 351 Starchy tissue. Mount a microtome section of potato, and note, under a power of about 3C0 diameters, the granules arranged in cells, and that on ad- dition of reagents, such as iodine, the granules are blued and the cell walls (cellulose) unaffected. Note also the difference between potato and corn starch granules. 352 Starch Faste. (1) To 1 Gm. dry starch add KHO solution, and note that, even in the cold, the granules swell and the milky mixture becomes translucent; and 353 (2) Boil another 1 Gm. of starch with plain water, and note same change. PART II. — ORGANIC CHEMISTRY. 165 starch, 354 which is used for laundrying and for surgical dressings. Starch is a very valuable food. Its best test is iodine, ■*' with which it forms a blue, which is somewhat lost on heating and re- gained on cooling." 55 Dextrine is the gum used on postage stamps, and by book- binders, and is made from starch in various ways, one of which Fig. 39. Arrowroot. Indian Corn. Potato. is to heat it to 300 F. for some hours. It is more soluble than starch, 360 and this explains the digestibility of crusts and toasted bread. It gives no blue with iodine, but a reddish, or wine color/' 61 304 Dissolve a few drops of starch paste in water, and add a drop of iodine solution. Note blue color. Divide this blue solution between four test-tubes. 355 Heat one and note that the blue color disappears, but re-appears on cooling, unless heated so strongly that the iodine is drawn ( ff . 356 To the second add KHO solution, and note the blue is discharged, but is restored on adding HC1. 357 To the third add AgNO a solution, and note that the blue disappears. 153 To the fourth add HgCL solution, and note again that the blue disappears. 359 Filter some diluted starch paste, and nota that it still responds to the tests for starch. 360 Dextrin. Take about I Gm. of commercial dextrin purchased by the demonstrator at the book-binder's. Add it to water, and note that it is soluble, sticky and sweet. 361 Add a drop of this solution to alcohol, and note that it falls as a white precipitate, dissolving again on addition of water. To some dextrin solution add iodine and note reddish (claret) color. 1 66 ESSENTIALS OF CHEMISTRY. Glycogen (generator of glucose) is a mealy, soluble powder found in the animal economy, especially in the liver. Like dex- trin it is a derivative of starch, but differs from it in being soluble and giving only a wine-color with iodine. It seems to be the form in which the carbohydrates are stored up in the liver to be used by the system as necessity arises. SACCHAROSES, C^H^On. This group includes cane-sugar, milk-sugar and maltose. Cane-sugar, beet-sugar, sucrose {saccharum U. S. P.) is found chiefly in sugar cane and also in beet roots as w r ell as in sugar maple. Cane-sugar occurs in the juice of many plants, especially in the stalks ; but in the fruit, unless very sweet, the glucoses occur oftener. Jt is made commercially as follows : The sap of sugai cane or the juice of beet-root is expressed by pressure or extracted with warm water and boiled with milk of lime, which saturates the acids and precipitates the albuminoid substances. The juice is then saturated with carbon dioxide to precipitate the lime, filtered through animal charcoal and concentrated in the " Robert's machine." By further evaporation in vacuum pans a thick syrup is obtained, and on cooling the solid sugar separates. This is raw or unrefined sugar, which when purified with a " pure sugar solu- tion " in a centrifugal machine becomes refined sugar. It is the most soluble, perfectly crystallizable and sweetest of the sugars, and the one most used in domestic economy. Its aqueous solu- tion is officinal as simple syrup (syrupus simplex). It does not respond to the tests for glucose. 362 Milk-sugar, as its name implies, occurs in milk, though occa- sionally elsewhere, as in the liquor amnii of the cow and in certain pathological secretions. Prepared by evaporating whey until the sugar crystallizes out, and is purified by repeated crystallization. It is harder, less soluble and less sweet than cane-sugar and used H6i Cane Sugar, (a) Apply Fehling's test to a solution of cane-sugar, and note that there is no reduction. 363 (b) Boil with 5 per cent. H 2 S0 4 or HC1, and, after neutralizing the acid with an alkali test for the presence of glucose. TART II. — ORGANIC CHEMISTRY. 167 in the trituration of medicines. 866 As it is less prone to fermenta- tion than other sugars, it is preferred in infant feeding. On fer- mentation, it forms lactic acid and not alcohol and acetic acid as do other sugars. Maltose is a sugar formed by the action of malt diastase upon starch, as in the " mash " of whiskey and beer ; also produced by the action of animal ferments on glycogen. In its power to re- duce Fehling's solution, 61 parts of maltose equal ioo of glucose. GLUCOSES, C 6 H 12 6 . Of this group we need mention only glucose and laevulose. Glucose, or grape-sugar, occurs in most sweet fruits, especially in the grape, and in honey. It is the sugar of the animal economy and the one that appears in the urine in diabetes mellitus. It is formed in nature largely by the action of acids and ferments 8,T_: ' 71 in conjunction with warmth and moisture on the amyloses, saccharoses, glucosides, etc., adding H 2 and breaking up their more complex molecules, thus : Starch, water, glucose cane-sugar, water, glucose. C 6 H ]0 O 6 + H 2 = C 6 H 12 6 ; and C 12 H. 22 O n + H 2 = 2C 6 H ]2 6 . * * 64 (c) Heat it dry and note that it melts into a yellowish mass, " barley- sugar," and afterwards becomes brown caramel,'" with some glucose. 365 (d) Add H 2 S0 4 and KHO to successive portions of dry cane sugar and of glucose, and note that the acid blackens the cane sugar first, and the alkali discolors only the glucose. • 66 Lactose. Taste it and dissolve it in w r ater, and note its sweet taste and that it responds to Fehling's and other tests for glucose. 167 Ferment. To successive portions of thin starch paste add (a) a few crushed grains of malt. 368 (b) Some saliva, obtained by chewing paraffine. Towards the end of the hour note the sweet taste and test for glucose. 369 Diastase. To some starch paste in a test-tube add some commercial diastase, and set in water not too warm for the finger to be held in it indefi- nitely. After a few minutes test for glucose. 370 Corn Syrup. Add 5 Cc. of H 2 SO + to a beaker of thin starch paste, and boil for an hour, or until a drop ceases to be blued by iodine. Add ex- cess of marble-dust to neutralize the acid and filter. Note its sweet taste; test a portion for glucose; evaporate the rest to a syrup, and allow it to cool. Note that it does so promptly and perfectly as cane-sugar. 371 " Skirt-tail sugar." Let the demonstrator boil some rags with dilute (5 per cent.) H 2 S0 4 for several hours, and at the laboratory hour neutralize with marble dust, filter and distribute to the students to test for glucose. 1 68 ESSENTIALS OF CHEMISTRY. Vast quantities of glucose are made commercially by boiling amyloses, such as starch, 370 or even cellulose 371 with dilute sul- phuric acid. Unless the cheap acid used be contaminated with lead, arsenic, etc., this artificial glucose (corn-sugar) 370 is as val- uable for food as the natural. Glucose is sometimes called dex- trose from its turning polarized light to the right. It is a strong reducing agent, upon which fact depend most of its tests (for these tests see article on urine). Laevulose occurs in fruits, etc. in association with glucose, and differs from it in turning the ray of polarized light to the left (hence its name). It may be obtained pure by separating it from the glucose of the invert-sugar made by heating cane-sugar with acids. Glucosides. This group includes a numerous class of substances, mainly of vegetable origin, mostly soluble in water and in alcohol ; and though differing greatly among themselves, possessing one common property, viz. : When acted upon by a ferment or a dilute acid, they decompose, producing, among other things, glucose™ Their chemical constitution is not thoroughly understood, but probably they are ethers of glucose. They generally have marked physio- logical action, and are therefore the active principles of the drugs in which they occur. Their names generally refer to their origin and terminate with re -in" A few of the most important are : Amygdalin, found in the bitter almond (amygdala), in the leaves of cherry laurel, and in the seeds of peaches, cherries and plums, associated with an albuminoid ferment, emulsin or synap- tase, which in the presence of heat and moisture decomposes the amygdalin into hydrocyanic acid, benzaldehyde and glucose. Salicin is the bitter principle in the bark of the willow (sa/ix). It has been employed as a substitute and adulterant of quinine, from which it may be known by the blood-red it gives with sul- phuric acid. 372 Boil I Gm. of salicin for 15 minutes in 10 Cc. of dilute (5 per cent.) H 2 S0 4 , and neutralize with excess of marble dust. Filter and test for glucose. PART II. — ORGANIC CHEMISTRY. I 69 Tannin. This, in several varieties, constitutes the active prin- ciple of vegetable astringents. Having an acid reaction and combining with various bases, organic and inorganic, it is often called tannic acid. With gelatin it forms an insoluble and imputrescible compound ; hence used from time immemorial to tan leather. It precipitates various metals, especially iron, with which it forms a blue-black, much used in inks and dyes, and making all vegetable astringents incompatible with solutions con- taining iron. Myronic Acid exists in black mustard, associated with myrosin, an albuminous ferment capable of converting the myronic acid into glucose and allyl sulphocyanate, to which latter the mustard owes its virtue. Hot water, by coagulating this ferment, renders a mustard plaster inert. Indican occurs in various plants, the indigofera; also in urine, being derived from indol, a weak base produced by the pancreas and taken up from the alimentary canal. It is a brownish, bitter, syrupy liquid, which, when fermented or treated with dilute acid, forms indigo-blue and a kind of glucose. Other important glucosides are : Arbutin, cathartic acid, colo- cynthin, digitalin, elate rin, gentia?iin, glycyrrhizin (from licorice), jalapin, santonin, saponin, solanin, etc. Bodies of the Arnmonia Type. Taking the molecule of ammonia, NH 3 , as a basis, and by substi- tuting for one or more atoms of its hydrogen one or more organic radicals or combinations of radicals, we can obtain a large num- ber of interesting and important substances • and the number is still further increased by polymerism, i. e., the faculty of the molecules duplicating themselves, so that one set of compounds may be formed on the type of NH 3 and another on that of N 2 H 6> and so on. Many of these substances have trade names alluding to some use or property, or in abbreviation of their chemical names, but their use is almost without excuse, as we have for them a very complete and systematic chemical nomenclature, the most 12 I70 ESSENTIALS OF CHEMISTRY. satisfactory, perhaps, in all chemistry. They bear the names of the radicals entering into their own composition, and end in "-amine" when those radicals are electro-positive, or in "-amide" when electro-negative and containing oxygen. For example : Amines — Ammonia. Ethylamine. Phenylamine. Trimethylamine. • H f C 2 H 5 (ethyl) ( C 6 H 5 (phenyl) f CH 3 (methyl) 3 " etc. ( H f C 2 H 5 (ethyl) f QH 5 (phenyl) ( CH : n^h; n^ h ; n^ h; n \ ch, (h (h (h (ch; Like ammonia, these bodies are alkaline, and combine with acids to form salts, appropriating instead of displacing their hydrogen, e. g. NH 3 -f- HC1 = NH 4 C1, ammonium chloride or ammonia hy- drochloride j in like manner NH a (C 2 H 5 )+HCl=NH a C 2 H B )HC1, ethylamine hydrochloride. Amides — Ammonia Acetamide. (Amine). C 2 H 3 (acetic rad.) f H ' f H 1SN H; INN H lH (C 2 I Acetanilide. Carbamide (Phenyl Acetamide). (Urea). f H f H C 2 H 3 ; NJ H (. C 6 H 5 (.phenyl) 1 >co «{» Aniline, 873 phenylamine, amidobenzene, made by the action !C H 5 °f nascent hydrogen (from HC1 and iron filings) on H nitrobenzene. It is a colorless liquid, but its com- H pounds, the aniline dyes, are coloring matters of great brilliancy. 374 - 376 373 Aniline from acetanilide. Crush together 1 Gm. each of NaHO and acetanilide; warm in a test-tube until they coalesce. Then invert the test- tube and continue heating as long as oily globules of aniline run out. Gather these in another test-tube and compare with the commercial article. Acetanilide. Aniline. Sodium acetate. (C,H 8 )NH(C 1 H 8 0)+NaHO=C 6 H ft NH 2 '4-NaC J II s O J . 374 Rosaniline. To about 2 Gm. of HgCl 2 add 3 drops of aniline, and warm until it turns green and then purple. When cool, add a little alcohol and a drop or two of HC1. Stir into a beaker of water, and note the purple rosan- iline hydrochlorate. 375 Nitro aniline. Shake a drop of aniline in a test-tube of dilute H 2 S0 4 ; mix a few drops of this with a few drops of strong H 2 S0 4 in a porcelain dish, and then add a trace of nitric acid, and note dark red color; a delicate test for nitric acid. PART II. — ORGANIC CHEMISTRY. 171 When taken or inhaled, aniline is an active poison, but some of its salts have found a place in therapeutics, especially the sulphate \ one grain doses for chorea and epilepsy. Trimethylamine is sometimes confounded with propylamine. r qh 3 It is a colorless, volatile alkaloid, with an ammoniacal, N -< CH 3 fishy odor. It is found in many animal and vegetable ( CH 3 substances, but is obtained from pickled herring. The hydrochloride is the salt used. Dose, ten to fifteen grains. Acetanilide. — This is a derivative of aniline, in which the acetic !C 6 H 5 radical, minus O, is made to displace an atom of H hydrogen. A crystalline, odorless solid, slightly sol- C 2 H 8 u ble in warm water, very soluble in alcohol ; made by the action of glacial acetic acid on aniline. In doses of five to ten grains, repeated every two or three hours, it is an antipy- retic and sedative. It is said not to affect the healthy tempera- ture, but to rapidly lower a fever. Its copyright name is " anti- febrin." Test: a yellow-green color with a green fluorescence when heated for some time with an equal weight of zinc chloride. Phenacetine. — The formula shows that this substance is closely !C 6 H 4 O C 2 H- allied to acetanilide. A white crystalline H powder, only slightly soluble in water. In C 2 H 3 doses of fifteen grains it causes a fall of temperature and a profuse sweat. Its effect is more persistent, and perhaps more dangerous than antipyrine, and may produce symptoms of aniline poisoning with hsemoglobinuria and jaundice, especially if an impure drug be used. Like acetanilide, it is used as a substitute for iodoform on painful ulcers, relieving pain and promoting healing. Antipyrine, C n H 12 N 2 0, a derivative of the artificial alkaloid, chinoline, is a white crystalline powder, soluble in water and in 376 Dissolve a few drops of this anilin in water in two test-tubes. To one add solution of chlorinated lime — a purple color is produced; to the other add some sulphuric acid and potassium chromate mixture — a blue color appears. 172 ESSENTIALS OF CHEMISTRY. alcohol, of a slight tarry taste and odor. With nitrous acid, it forms a green precipitate, and is therefore incompatible with spirits of nitrous ether. This green color is a test, not only for antipyrin, but for the presence as well of nitrous ether, e. g. 9 in any specimen of " sweet spirits of nitre." In doses of ten to fifteen grains it is a valuable antipyretic and anodyne. The hydrochloride is the salt used. Proteids. The name proteid is given to a numerous and varied class of bodies in allusion to their occupying first (protos, first) rank among the proximate principles of animal and vegetable tissues. They are all highly nitrogenous, and are the only substances cap- able of living. They originate only in plant life, and are appropri- ated by animals and constitute the major part of the solid portion of their tissues and fluids, except the sweat, urine and bile. Their ultimate analysis shows about 50 per cent, carbon, 7 per cent, hydrogen, 23 per cent, oxygen, 16 per cent, nitrogen and 4 per cent, sulphur. The empirical formula, C 72 H 112 N 18 S0 2 . 2 , has been suggested ; but of their rational formula we know almost nothing, except that their molecules must have great weight and complexity. They are amorphous, colorless, odorless, colloid (uncrystallizable) bodies; and, except peptones, are not osmotic — do not dialyze — do not diffuse through animal membranes. Some are soluble, others insoluble. Some are rendered insoluble by heat or by certain acids, alcohols and metallic salts, these serving as tests for the proteids, and the proteids as antidotes to them. Tests : — (1) They are all precipitated by alcohol, and, in time, coagulated. (2) Heated with strong nitric acid (xanthoproteic test) they turn yellow, owing to the formation of xanthoproteic acid ; and on the addition of an alkali, become orange. (3) Biuret test : Add a few drops of dilute copper- sulphate solution and an excess of KHO ; a violet color appears. PART II. ORGANIC CHEMISTRY. 1 73 (4) Millorrs reagent colors the proteids purple-red on heating. This reagent is composed of mercury one part, nitric acid one parts, plus two volumes of water. Classification of the Proteids : — The physiologists divide the proteids into eight classes ; 1, native albumins; 2, globulins; 3. derived albumins; 4, fibrins: 5. peptones: 6, albumose ; 7, coagulated proteids: 8. lardacein. The latter (lardacein) is an amyloid substance found as a pathological infiltration in various organs. 1. Natural Albumins are so called because they occur natur- ally in the blood, lymph, chyle, etc., also in the whites of eggs and in plants. Natural albumins comprise (a) serum albumin, egg albumin, (c) vegetable albumin. As a class these albumins are soluble in water ; not coagulated by dilute acid unless heated above 167 F. ; coagulated by strong acids and by heat. rum albumin in solution is a white or pale yellow fluid, 577 slightly alkaline, and is coagulated by heat and by acids. It is not readily coagulated by alcohol or ether. Egg albumin (found in solution in the white of ?gg)~~~ is co- agulated by ether and very rapidly by alcohol ; otherwise has the same characteristics as serum albumin. getable albumin (found in nearly all vegetable juices) is co agulated by heat and by acids. Paralbumin and Jfefalbumin, found in ovarian cysts, belong to this class of natural albumins. 2. Globulins are, as a class, insoluble in pure water; soluble in dilute but precipitated by strong sodium chloride solution ; co- agulated by heat, and precipitated when carbon dioxide gas is passed through them. 377 1 Maybe easily obtained from blood, from which it separates in coagulation, but is sold dried for calico printing and sugar refining. of Egg Albumin. Through a small hole in the end of an egg pour out the white, leaving the yolk in the shell. Break up the white with a glass rod and strain through wet muslin. 174 ESSENTIALS OF CHEMISTRY. Globulins comprise (a) para- or serum-globulin, found in blood- serum and in lymph ; (b) fibrinogen found in blood-plasma, lymph, chyle, etc.; (c) myosin, 319 found in muscle, and, by its coagulation, responsible for the condition known as rigor mortis ; (d) crystalling found in the crystalline lens ; (e) vifellin, 381 found in the yolk of egg. 3. Derived albumins (albuminates) are as a class insoluble in water and in dilute sodium chloride solution, but soluble in dilute acids and alkalies; not coagulated by heat. Derived albumins comprise : (a) acid albumin™ formed by treating natural albumin with dilute acid (HC1) for a considerable while; (b) syntonin,™ 5 made by digesting myosin with weak HC1, and precipitating with an alkali, when it appears as a pasty, whitish mass ; (c) alkali albumin, made by treating natural albumin with an alkali ; 384 is slightly soluble in water and in sodium chloride solution, differ- ing therefore from acid albumin; (d) casein, made by diluting milk with four volumes of water and acidulating with acetic acid until the milk contains about T \- per cent. ; (e) Legumin (vege- 379 Preparation of Myosin. Chopped lean beef is soaked in water, and the water expressed through a cloth, and the process repeated until all albumin is removed. The residue is then soaked in 10 per cent, salt solution, which when expressed is found to contain the myosin. 380 Preparation of Crystallin {globulin). Grind up with 10 Cc. of water in a mortar, the crystalline lens of an ox, and filter off the water, which removes the albumin. Rub up the residue with 10 Cc. of 10 per cent, salt solution which dissolves the crystallin. 38i Preparation of Vitelin. Wash the yolk free from the white, and shake it with ether in a test-tube to remove the fats. Pour off all the ether possible, and let the rest evaporate. Impure vitellin remains. Water does not dissolve it, though salt water makes a milky solution. 382 Preparation of Acid Albumin. Stir 20 drops of glacial acetic acid with the white of one egg until it forms a gelatinous mass of acid albumin. This is then dissolved in a beaker of warm water for use. 383 Preparation of Syntonin. Chopped beef is repeatedly soaked in water, and the water expressed to remove the serum albumin. The residue is then digested in a 0.2 per cent, solution of HC1, and the solution expressed con- tains the syntonin or muscle acid-albumin. 384 Preparation of Alkali Albumin. With the white of one egg, stir 3 Cc. of KHO solution. Dissolve the gelatinous mass in a beaker of water to use as a solution of alkali albumin. PART II. ORGANIC CHEMISTRY. 1 75 table casein), found in the seeds of peas and beans, also in almonds, and reacting like milk casein. 4. Fibrins are, as a class, insoluble in water, difficultly soluble in strong acids and alkalies, whereby they are changed to de- rived albumins; coagulated by heat. Fibrins comprise (a) blood fibrin; produced by the action of fibrin ferment upon the* fibrinogen and fibrinoplastin of blood, lymph, chyle, etc., whereby a clot is formed ; insoluble in water, alcohol or ether, but slowly soluble in dilute acid; (b) Glutin (vegetable fibrin) existing in vegetables and probably a mixture of several proteids ; insoluble in water, alcohol or ether. 5. Peptones, as a class, are soluble in water, acids, alkalies and sodium chloride solution. They are precipitated by alcohol, tannic acid, bichloride and potassium-mercuric chloride. With C11SO4 solution (a few gtt.) and KHO in excess, peptones give a red color. Pepsin of the gastric juice and the trypsin of pan- creatic juice, in the process of digestion, act upon proteids to con- vert them into peptones, which are diffusible (osmotic). 6. Albumoses are soluble in dilute sodium chloride solutions and in water, give a red color, as do the peptones, with CuS0 4 and an excess of KHO. Albumoses are intermediate between acid-albumin and peptone. 7. Coagulated proteids are as a class, insoluble in water, sod- ium chloride, dilute or alkali. They are the result of the action of heat, acids, alcohols, etc., on true albumins or globulins. 8. Lardacein, as stated above, is found as an amyloid infiltra- tion in various organs and tissues in persons long suffering from wasting disease. In composition, it is a proteid, but is not di- gested by pepsin and HC1 and with iodine it strikes a red ; or a blue, if previously treated with sulphuric acid. Alkaloids. Alkaloids (alkali-like) are organic alkalies, a class of bodies of alkaline reaction and capable of neutralizing acids and forming with them distinct and crystallizable salts. They are undoubtedly amines or amides, u e., ammonia in which one or more atoms of 176 ESSENTIALS OF CHEMISTRY. hydrogen in the molecule, NH 3 , are replaced by one or more or- ganic radicles or combinations of organic radicles, but the mole- cules seem to be far more complex than those artificial alkaloids. Of late years chemists have made a number of amines, some of them similar, if not identical with certain natural alkaloids ; and the time seems not far distant when our most costly and complex alkaloids will be made artificially ; in fact, all that seems to pre- vent it now is not knowing the exact constitution of such complex molecules. In plants alkaloids are not found free, but combined with some vegetable acid forming a salt. Their salts (except tannates) are usually soluble and intensely bitter; the free alka- loids, being much less soluble, are much less bitter. Those alka- loids (as conine and nicotine) that contain no oxygen are liquid ; but the great majority of them are white powders. Alkaloids are so seldom prescribed in the free state that when the simple name of an alkaloid is written in a prescription the druggist puts up its most common salt. The names of alkaloids end in "-ine" and are derived from the names of the plants in which they exist or from some characteristic property. The intense effect alkaloids exert on the animal organism makes them generally the active principles of the drugs in which they are found. But the active principle of a drug is not always an alkaloid. The alkaloids include the majority of our most potent remedies and powerful poisons. Tannin is a common antidote, but most important is the prompt evacuation of the stomach and the intelligent use of physiological antagonists. The alkaloids, even those of medical interest, are so numerous that to give each separate consideration would cover a great por- tion of the materia medica. We can mention but a few of the most important. See Table, page 178. Ptomaines are putrefactive alkaloids, — The word "ptomaine" was first used by an Italian, Francesco Selmi, who discovered in decomposing organic matter certain basic, alkaloidal bodies. He recognized their resemblance to the vegetable alkaloids, and called them in contradistinction ptomaines (n-ra^a, a corpse) or cadaver PART n, — ORGANIC CHEMISTRY. I 77 alkaloids. Later study has taught us that the various bacteria act upon organic matter, and with the requisite amount of heat and moisture, cause its decomposition with the production of pto- maines. As a rule, bacteria will cause these putrefactive changes only in dead animal or dead vegetable matter, but in pathological states it is possible for germs to flourish and multiply in the living 1 " organism, causing the same putrefaction, and hence the same pro- duction of ptomaines. The different bacteria produce different ptomaines ; thus the typhoid bacillus produces typhotoxine, the tetanus bacillus produces tetanine. It is generally accepted to- day tnat the symptoms of infectious diseases and specific fevers are due solely to the poisons produced by bacterial growth in the living organism : and since analogous conditions and symptoms may be brought about by the administration of the ptomaine ob- tained from any given bacteria, this view is evidently correct. The poisoning that frequently results from eating spoiled meat, fish, etc., is due to ptomaines. The symptoms of poisoning by ptomaines resemble those by the vegetable alkaloids, except that there is usually more gastro-intestinal irritation. The resemblance of the physiological effects and chemical tests to those of such alkaloids as strychnine, morphine, conine, nicotine, atropine and veratrine, is apt to, and doubtless has often led to the escape of the guilty and the condemnation of the innocent. Among the poisonous ptomaines may be mentioned, besides typhotoxine and tetanine, tyrotoxicon. a very poisonous alkaloid, discovered and described by Vaughan. It is found in spoiled milk and in ice cream and cheese made from it. Tyrotoxicon poisoning is char- acterized by a chill, with nausea and vomiting, epigastric pains, griping, purging and perhaps collapse and death. Spasmatoxine is obtained from the bacillus of tetanus, and like tetanine, which is obtained from the same bacillus, produces decided convulsions. Other poisonous ptomaines are, isoamylamine, a very poison- ous, and rapidly fatal alkaloid, found in decomposing yeast and in cod- liver oil ; tetanotoxine, susotoxine, neurine, coline and mus- carine (obtained from poisonous mushroom), are decidedly poisonous ptomaines. 178 ESSENTIALS OF CHEMISTRY. Among the non-poisonous ptomaines may be mentioned : Neu- ridine, methylamine, trimethylamine, ethylamine and diethylamine, pyocyanine (from bacillus pyocyaneus), mydine, etc. Putrescine and cadaverine are only slightly poisonous. Since some ptomaines are not poisonous and others are decidedly toxic, it has been considered best to invent the term " toxines " for the poisonous ones. Leucomaines are a class of alkaloidal substances produced in the living body as a result of fermentative changes or of the processes of retrograde metamorphosis, as, for example, urea. They are eliminated in the various excreta. If retained, as in uraemia, or produced in abnormal quantity, as in dyspepsia, they act deleteriously on the nerve-centers, causing vertigo, lassitude, drowsiness, vomiting, purging and coma. Some elevate, while others lower the temperature. Of the more important leucomaines may be mentioned : Kreatine, kreatinine, xanthine, hypoxanthine, paraxanthine, heteroxanthine, pseudoxanthine, spermine, sala- mandarine, etc. Most of the leucomaines are non-poisonous ; some few are decidedly toxic. Bacterial Proteids. — Very little is known of bacterial proteids since they quickly decompose. The bacterial proteid poison of diphtheria, of tetanus, of cholera and of typhoid have been iso- lated. These proteids, or toxalbumins, as they are sometimes called, are formed by the action of bacteria on albuminous material ; and their effect upon the animal organism, when administered internally or hypodermatically, is to produce symptoms identical with those of the bacterial infection. Antitoxine. — A few words must be said about antitoxines : It has been found that when an animal has recovered from certain infectious diseases, there is present in the serum of that animal's blood something which confers partial or complete immunity to the animal against further attacks from the same disease ; and this serum, when injected into other animals exhibits the same protective power. The composition of this substance is un- known, but on account of its antitoxic effects it has been called antitoxine. We have already a diphtheria antitoxine, a tetanus PART II. ORGANIC CHEMISTRY. 179 antitoxine, a streptococcus antitoxine, etc. Clinical results have shown conclusively that a new field of therapy is open here to the physician. Let us hope that this " serum-therapy of Behring " will do as much in other infectious diseases as has already been accomplished in variola by Jenner's discovery of vaccine. TABLE OF COMMON ALKALOIDS. Name. Formula Source Remarks. r Crystalline ; morphia gives a blue Morphine Codeine Narcotine Narceine C 17 H 19 N0 3 C, s H 21 N0 3 C,,H., 3 N0 7 "] Opium 1 « \ « • j with FeCl.^, and a red with HNO s . These alkaloids and several others exist in opium in combination with meconic acid, which gives with Fe.,Cl 6 a red color not discharged by HgCl.,. Apomorphine C 17 H 17 N0 2 Morphine Made by heating morphine with HC1; a systemic emetic. Quinine C 20 H 2i N 2 O 2 1 Quinidine « f All crystalline except quinoidine, Quinicine t( 1 Cinchona J hark which is a resinous mass. To Quinoidine it test for quinine, add chlorine Cinchonine C 19 H 22 N 2 water, shake, and then add aq. Cinchonidine a I ammonia; a green color. Cinchonicine a J Strychnine C 21 H,,N,0 2 Nux vomica Crystals; gives a purple with H,S0 4 K,Cr.,0 7 or MnO.,. Brucine CjgH^NA u Crystals; gives a red with HN0 3 . Aconitine c; h;.no 7 Aconite ) Colchicine C 17 H 19 N0 5 Colchicum V Crystals; very poisonous. Veratrine C 32 H 52 N 2 8 Veratrum J Atropine C 17 H.„NO, Belladonna ) Hyoscyamine c 15 h.;no 3 Hyoscyamus y Crystals; used to dilate the Homatropine C 16 H 22 N0 3 Atropine ) pupils. Hyoscine C 1T H 2l N0 4 Hyoscyamus Sedative and hypnotic; crys- tals. Crystals; soluble in water. Caffeine C 6 H I0 N + O 2 Coffee Theine it Tea Crystals; soluble in water. Theobromine C 7 H 8 N,0 2 Chocolate Stimulant, crystals. Cocaine Coca leaves Crystals; soluble in water; weakly basic ; local anaesthetic. Physostigmine C 15 H. 21 N,0 2 Physostigma Crystals; contracts the pupils. (Eserine) (Calabar bean) Pilocarpine C n H 16 N 2 2 Jaborandi Crystals; a powerful diaphoretic. Urea CH 4 N 2 Urine Crystals; may be made artifi- cially by heating NH 4 CNO. Nicotine o 5 h 7 n Tobacco Liquid; powerful poison. Conine C 8 H 15 N Hemlock (t a a PART III.— CLINICAL CHEMISTRY. THE URINE. The urine is a fluid secreted continuously by the kidneys, and is the chief means by which the nitrogenous waste of the body is discharged; 385 A specimen, to be representative, should be a portion of the whole twenty-four hours urine, for considerable variation in cora- * 85 The rationale of its secretion is one of transudation, osmosis, and elabo- ration. Owing to the resistance encountered by the blood in its exit through the efferent vessel, there is an increase of blood pressure in the Malpighian tuft and a transudation of the water of the blood with some dissolved salts into the capsule. From loss of water the blood is very much thickened when it reaches the second capillary system surrounding the convoluted tubes, which contain the thin, watery transudation from the Malpighian bodies. Here are the essential elements of a complete osmometer — an animal membrane, com- posed of the thin wall of the capillary and the delicate basement membrane of the tube, with a dense fluid (the thickened blood) on one side and a thin saline solution on the other. An interchange now takes place of the water from the tube to the blood, and of the products of retrograde metamorphosis (urea, etc.), and salts from the blood to the tubes, concentrating the fluid in the latter, making it urine, while the albuminous constituents of the blood, not being osmotic, are retained. An elaborative function has long been attrib- uted to the epithelial cells lining the convoluted tubes, for it was observed that whenever the tubes lost their epithelial lining (as in some forms of Bright's disease), urea, etc., failed to be eliminated. This function of the cells may be demonstrated by injection into the veins of a rabbit a solution of sulph-indigotate of sodium. If the animal be killed within a few minutes, none of the coloring matter will be found in the capsules, while the cells lining the tubes will be stained blue. If, however, an hour be allowed to elapse, even the cells will be found colorless and the coloring matter will be seen only in the urine. Our conclusion drawn from this is that the production of urine is chiefly an elaborating or secreting process, regulated in its fluidity by the glomerular system; that the water and some of its salts are secreted by the glomeruli, the peculiar anatomical construction of which permits a varying degree of activity corresponding chiefly with the varying degree of blood pressure and blood fluidity; while in the main, the solid excretory pro- ducts of the urine are elimated by the epithelium of the renal tubules, through their vital, selective or secretory power, as in all other glandular structures of similar anatomical construction. (180) PART III. CLINICAL CHEMISTRY. l8l position and properties may occur during the day. Especially is this true of traces of albumin and sugar. When this is impractic- able, that passed before breakfast is generally preferable, because farthest from a meal. When significant variations during the day are suspected, several specimens may be taken 33^ at different hours. For microscopical exami- nation, a few ounces of the urine in a stop- pered vial, or covered conical glass, Fig. 44, are set aside for several hours until the sedi- ment, having settled to the bottom, can be examined. A much more improved and satis- factory method is by the use of the centrifuge, as thereby the precipitate can be obtained at once from fresh urine. Physical Properties. Normal urine is a transparent, aqueous fluid, of a pale yellow color, characteristic odor, faint acid reaction, and of a specific gravity of 10 20 when passed in the average quantity of about 1500 Cc. {48 fl. ounces) in the twenty four hours. This description is to be taken with much allowance, for very wide variations occur even in health. With these variations the student must become thoroughly familiar before he is capable of interpreting a speci- men. Quantity. — hi health, the average adult secretes about 1500 Cc. (48 fl. ounces) a day, most in the afternoon and least at night; but the quantity may vary widely (from 500 Cc. to 5000 Cc.) de- pending upon, (a) the quantity of liquids ingested, and (b) its vicarious elimination by the skin, lungs and bowels. In disease, it may be increased (polyuria) or diminished (olig- uria) or even suppressed (anuria). Polyuria occurs in (a) diabetes mellitus or insipidus; (b) con- tracted and amyloid kidney; (c) pyelitis; (d) cardiac hyper- trophy; (e) after the crisis of acute diseases; (/) during rapid absorption of exudates and transudates ; (g) in nervous excite- 152 ESSENTIALS OF CHEMISTRY. ment, as epileptic and hysterical attacks or even fright and an- xiety ; (h) after administration of diuretics. Oliguria occurs in {a) fevers and inflammatory affections; (b) acute nephritis ; (V) excessive elimination of water by other chan- nels, as in sweating, diarrhoea, etc. ; (d) conditions of lowered arterial tension as in heart failure, exhaustion, shock, etc. Anuria or suppression of urine differs from oliguria only in degree and should not be confounded with retention, in which case the urine is secreted, but retained in the bladder. Transparency. — Normal urine is not always transparent, nor is transparent urine always normal. Some degree of opacity may be due to (a) Mucus, which, with entangled epithelial cells, may be observed as a slight cloud in many specimens of healthy urine, especially of females because of the larger area of mucous surface in that sex. This faint cloud may be seen floating at any depth and is unaffected by most chemicals except acetic acid, which may slightly increase the opacity by coagulating the mucin. The mucus is usually removed by filtration ; (b) Urates (of Na, K, Ca, and Mg), which often form a precipitate in the urine, especi- ally when allowed to cool, as in standing over night in a cold room. The test for this sediment is heat, which quickly dissipates it. (Y) Earthy phosphates (of Ca and Mg), which may give an opacity to normal urine if it is alkaline or even ceases to be acid. The test for this sediment is that it promptly clears up, on the addition of a few drops of any acid, while heat would only in- crease it. (d) Fungi (bacteria, penicillia, sarcinae, etc.), especi- ally in decomposing urine. A urine may be abnormally opaque or cloudy from the above- mentioned causes, or from the presence of blood, pus, epithelia, tube casts, fat globules/ 86 etc. When due to blood, pus or organ- ized detrita, the opacity is increased by heat or acids because of 38(i In chyluria the urine is mixed with chyle, the fat being in a state of emulsion, and is milky, and if alkaline, is even viscid. I have seen it only a few times in this country, but it is common in the tropics, and is due to the presence of the filaris sanguinis hominis. PART III. CLINICAL CHEMISTRY. 1 83 the precipitation of albumin which is always present in liquor san- guinis and liquor puris, and is usually associated with tube- casts, etc. Fluidity. — Healthy urine is neYer otherwise than an aqueous fluid, flowing and dripping with ease ; but in certain diseased conditions, abnormal quantities of mucus, or the presence of pus or fat, especially if the urine be allowed to decompose and be- come very alkaline, may make it more or less viscid. Color. — Healthy urine is of a pale yellow, or amber color, the depth of which varies greatly according to the quantity of water present and the consequent degree of concentration or dilution. Aside from abnormal degrees of the above, pathological variations in color may be the result of (a) a diminution of the normal color- ing matters, as in anaemia, diabetes and certain forms of kidney disease; (5) an increase of the normal coloring matters, as in fever and other diseases destructive of blood and tissue ; (c) by the presence of abnormal substances, as biliary and blood color- ing matters. (a 7 ) Moreover, the urine may be colored after the administra- tion of certain drugs, as senna, santonin, rhubarb, carbolic acid, prickly pear, etc. Odor — Urine has a charactetistic odor, the strength of which depends mainly on its concentration. When freshly passed, it has also an aromatic fragrance, due to certain volatile ethers. The more concentrated the urine, the stronger the odor because of the larger quantity of urea it contains. Diabetic urine exhales a sweetish and fruity smell, owing to the presence of acetone. In certain forms of dyspepsia and of liver trouble, the odor of the urine is almost pathognomonic. Medi- cines and certain articles of food often impart a peculiar odor, as turpentine the odor of violets, asparagus and cauliflower a rank, disgusting smell ■ also cubebs, copaiba, sandalwood-oil, garlic, tolu and salol, impart their characteristic odors. Reactio?i. — Normally the urine of the whole twenty-four hours will average an acid reaction ; but great variations occur during 1 84 ESSENTIALS OF CHEMISTRY. the day. Before meals it will have a high degree of acidity, but after meals becomes nearly neutral or even alkaline. This is due to the ingestion of food, which is largely alkaline, and to the ab- straction of acidulous principles from the blood to form acid gas- tric juice. It has also been observed that urine passed on rising in the morning is especially acid. This is probably owing to the fact that during sleep less carbonic acid is exhaled from the lungs, and less perpiration (acid) given off by the skin. The urine is especially acid whenever the albuminoid tissues are being rapidly oxidized as in fever, diabetes, carcinoma, etc. It is especially alkaline after the ingestion of alkaline salts or of neutral salts of vegetable acids and alkali metals, the acidulous radicals of which are oxidized in the blood, so that the salts appear in the urine as carbonates. This explains the alkaline urine of vegeta- rians and herbiverous animals. Fig. 45. Sediment from a urine in " acid fermentation." (a) Fungus; (b) amorphous sodium urate; (c) uric acid; (d) calcium oxalate. The reaction of urine is important to the physician, as it may favor or prevent irritations of the kidneys and bladder or the for- mation of sediments and concretions. The acidity of urine is PART III. CLINICAL CHEMISTRY. 185 due, not to free acid, but to acid sodium phosphate (NaH 2 P0 4 ) occurring in consequence of carbonic, uric and hippuric acids, seizing on to a portion of the sodium of the phosphate (Na 3 P0 4 ). The degree of acidity is best measured by a decinormal alkaline solution (see Acidimetry, page 96). An acid fermentation, attended by a decomposition of mucus and coloring matters and a production of acetic and lactic acids, sometimes occurs in urine that has stood for some at a mod- erate temperature (Fig. 45). After a while, more quickly in warm weather, the alkaline fermentation begins, caused by the development of the micrococcus ureae (Pasteur). The urea is con- verted into ammonium carbonate, thus: (NH 2 ) 2 CO^ 2H 2 = (NH 4 ) 2 C0 3 . This gives the urine an ammoniacal odor and alka- line reaction, and it becomes opaque from the precipitation of urate of ammonium (Fig. 46), and the earthy phosphates and the Sediment from a urine in the " alkaline fermentation." {a) Ammonium urate; (b) ammo- nio-magnesium phosphate; (c) bacterium ureae. development of bacteria. Pus and blood or vessels tainted with urine previously fermented greatly hasten this change. The re- action is recognized by litmus paper. If acid, the blue litmus is 13 i86 ESSENTIALS OF CHEMISTRY. turned red ; if alkaline, the red litmus is turned blue ; if neutral there is no change in either. If alkalinity be due to ammonia (volatile alkali) the blued paper gets red again on drying. Specific Gravity. — Though the average specific gravity is 1020, it exhibits, even in health, great variations, the extremes being 1002 after copious use of water and diuretics, and 1040 after ab- stinence from fluid and the elimination of water through other means, as profuse perspiration or copious diarrhoea. The amount of solids varying but little in health, fluctuations in specific gravity are due mainly to variations in the amount of water ; so, as long as the inverse proportions between specific gravity and volume of urine is preserved, variations need cause no alarm. Marked de- partures, however, from this inverse ratio are of the gravest import. A specific gravity too small for the volume of urine indi- cates renal defect and heralds uraemia ; a specific gravity too high would indicate glycosuria or excessive tissue waste, as in fevers. Fig. 47. Fig. 48. 30 40 Diagram. Specific gravity is usually measured by an instrument called a hydrometer or urinometer (Fig. 47), which is a hollow, glass float, weighted with mercury and having a long, graduated neck. The graduation begins above at 1000, because the heavier the urine PART III. CLINICAL CHEMISTRY. 187 the less deeply will the instrument sink and the further ne neck will protrude from the surface. It is well to test a new urino- meter by immersing it in water at 6o c F. (15.5 C), when it should sink to o, or 1000, on the scale. Urinometers are usually provided with a cylinder, or jar, as shown in the figure, but a large test-tube will answer. This is about three-fourths filled ; the urinometer is then introduced, and when still, the specific gravity is read off. The cylinder or test-tube should not be too narrow, lest the urinometer be attracted to and catch against the sides, and not rise as high or sink as low as it should. One of the best urinometers on the market is Squibb's, in which the jar is sharply fluted inward near the middle and the bulb of the float is made oval so as to present little surface for contact. A ther- mometer is also provided. For every seven degrees of tem- perature above the normal (6o° F. or 15 .5° C.) one degree of specific gravity should be added to the reading. The fluid being attracted up around the stem, the reading should be made not along the line c d y as in the diagram (Fig. 48) suggested by Dr. Leffmann, of Philadelphia, but along a b, which represents the true level of the liquid. To approximate the amount of solids in any urine; {a) the last two figures of the specific gravity represent the number of grains of solids to the fluid ounce ; (b) doubling the last two figures of the specific gravity, gives the per cent. Thus, if the urine be of the specific gravity 1020, and the daily volume fifty ounces : — (a) 20 (grains per fluid ounce), multiplied by fifty (ounces daily volume) gives 1000 grains of solids per diem; (b) .020 X 2 = .040 or 4 per cent, which multiplied by fifty (ounces daily volume) gives 2 ounces of solids per diem. The solids of the urine may be accurately determined by tak- ing a certain volume of urine, e. g., 100 Cc. and evaporating it in a previously weighed porcelain dish over a water-bath, until it no longer loses weight, when it is finally weighed and the weight of the dish subtracted. 155 ESSENTIALS OF CHEMISTRY. Chemical Constituents. The average composition of a thousand parts of urine is about as follows : f Water 950.00 Urea 26.20 Organic J Creatine an ^ kreatinine, xanthine and allantoine .80 I Urates of sodium and potassium 1.45 I Hippurates of sodium and potassium 70 L Mucus and coloring matters .35 p Phosphates of sodium and potassium 3.75 Ino anic j Phosphates of calcium and magnesium 90 j Chlorides of sodium and potassium I2 «55 ^ Sulphates of sodium and potassium 3.30 1000.00 Pathologically there may be present also albumin, glucose, blood, bile, etc., besides various other sediments. »{! Urea, J:>CO, or carbamide, is the most constant and abundant organic constituent of the urine, and being the main nitrogenous excretion, is the index of nitrogenous waste, whether of food or of tissue. Its average amount is about one ounce per diem. Urea may be obtained by extracting it from the urine, or artificially by heating cyanate of ammonium, with which it is iso- meric [(NH 4 CNO= (NH 2 ) 2 CO).] It crystallizes in colorless prisms, very soluble in water, and behaves like an alkaloid, combining readily with nitric and oxalic acids to form salts. Both of these salts may, by adding nitric or oxalic acid, be precipitated from concentrated urine as colorless, rhombic or hexagonal plates. 387 (Fig. 49.) It was formerly believed that the kidneys were the seat of the 387 Test for urea. On a glass slide place a drop or two of suspected fluid, add a drop of nitric acid, warm over a spirit lamp; if urea is present the characteristic rhombic or hexagonal crystals of nitrate of urea can be seen with a microscope. PART III. — CLINICAL CHEMISTRY. 189 formation of urea, but this has been proved an error, from the fact that after complete extirpation of the kidneys, urea continues to be formed. It is believed now that the liver, and perhaps also the spleen, and the lymphatic and secretive glands, take active part in the formation of urea. Its formation is markedly diminished in degenerative changes in the liver, as in acute yellow atrophy of the liver. Urea is abundantly formed in diabetes ; the activity of the hepatic cells being much increased, sugar and urea are formed in great quantities, and after being passed into the blood are excreted by the kidneys. In suppression of the urine, due to diseases of the kidney, the formation of urea continues and is accumulated in the system, giving rise to uraemia. A meat diet increases the quantity of urea and a vegetable diet diminishes it. Fig. 49. (a) Prisms of urea; (5) hexagonal plates; and (c) rhombic plates of nitrate of urea. In the course of many diseases it is important to estimate the amount of urea excreted day by day. A rough estimate may be based on the specific gravity. For, since urea is the largest solid ingredient in urine, it follows that if sugar be absent, albumin in T90 ESSENTIALS OF CHEMISTRY. small amount or removed, and the quantity of chlorides normal, variations in specific gravity must be due mainly to variations in the amount of urea. The exact methods most generally employed consist in decom- posing the urine into nitrogen and carbon dioxide, by means ot sodium hypochlorite or hypobromite, and measuring either the volume of gas evolved or the specific gravity lost by the decom- position. Davy's Hypochlorite Method. — A graduated tube closed at one end is one-third filled with mercury. A measured quantity of the urine (a drachm or half drachm, according to capacity of tube) is then added, and the tube is next filled to the brim with the Fig. 50. Fig. 51. ni w Doremus'. Davy's. hypochlorite solution (liq. sod. chloratse, U. S. P.). Closing the opening with the thumb, the tube is inverted over a strong solu- tion of common salt in a dish (Fig. 50). The mercury runs out and the salt water rises to take its place, while the urine and soda mixture, being lighter, remain in the upper part of the tube. Here the gas from the decomposing urea collects. The decom- position is complete in three or four hours, when the amount of PART III. CLINICAL CHEMISTRY. 191 the gas may be read off by the graduations upon the tube, every cubic inch representing .64 grain (or 1 cubic centimetre repre- senting 2.5 milligrams) of urea. This method is now but little used. Doremus* Hypobromite Method. — The sodium hypobromite is prepared by adding 1 cubic centimetre of bromine to 10 cubic centimetres of sodium hydrate solution (100 grammes to 250 cubic centimetres of water, or 6 ounces to one pint) and diluting with 10 cubic centimetres of water. Tilt the ureometer (Fig. 51), and pour the hypobromite into the long arm, completely filling it. Draw the urine to be tested into the pipette to the graduation. Pass the pipette into the ureometer as far as the bend, and compress the nipple slowly. The urine will arise through the hypobromite, and the gas evolved will collect in the upper part of the tube. The ureometer is graduated to indicate either the number of milligrams of urea to the cubic centimetre of urine or the number of grains to the fluid ounce. This method is so quick and simple that it is the one generally employed by physicians. Squibb 's Apparatus is similar to the foregoing, but has the ad- vantage of employing the easily obtained liquor sodae chloratae U. S. P. Fowler's Method. — The specific gravity of the urine is carefully determined as well as that of the liq. sodae chloratae (U. S. P.) to be used. One volume of the urine is mixed with exactly seven volumes of the liq. sod. chlor. and set aside for two hours, or until effervescence ceases. The specific gravity is again taken. As the reaction begins immediately on mixing the fluids, the spe- cific gravity of the mixture must be determined by calculation. This is done by adding to the specific gravity of the urine seven times that of the liq. sod. chlor. and dividing the sum by eight. Each degree of difference in specific gravity of the mixture before and after the decomposition represents three and a half grains of urea to the fluid ounce of the day's urine, or seven grams to the liter. 192 ESSENTIALS OF CHEMISTRY. Example : Quantity of urine in twenty-four hours 46 oz. Sp. gr. of the urine 1020 Sp. gr. sod. chloratse 1042 ^/..jx . . ,1042 X 7 + I02 ° \ , (Calculated) sp. gr. mixture ( — -' — — ) 1039.2+ o (Actual) sp. gr. mixture after reaction 1036.2 1939.2— 1036.2 = 3 ; 3 X 3^ = 103^ grs. of urea to the ounce of urine ; 10*^ X 46 = 483 grs. of urea passed in the twenty-four hours. Kreatine and Kreatinine, occur in normal urine, but so spar- ingly as to be of little practical importance. They are closely allied chemically and physiologically with urea ; appearing in acid urine as kreatinine, C 4 H 7 N 3 0, and in alkaline as kreatine, C 4 H 9 N 8 2 , differing in composition only by the molecule, H 2 0. Xanthine and Allantoin are substances closely allied to uric acid ; occur in normal urine so sparingly as to be of little practical importance, and need only be mentioned in this connection. Uric Acid (H 2 C 5 H 2 N 4 3 ), formerly called lithic acid, is found in the urine of carnivora : in that of herbivora it is largely replaced by an analogous substance — hippuric acid. Gout is characterized by an increased production of uric acid, and the so-called " chalk-stone " deposit in the joints during that disease is sodium urate. Free uric acid is so very insoluble that when- ever it exists in urine it is always a precipitate. It appears as minute reddish grains, which under the microscope are seen to be modifications of rhombic crystals, always stained with the coloring matter of the urine. They often deviate widely from the typical rhomb, as shown in Figs. 52 and 53, but an experienced eye will readily recognize them. Normally, uric acid as soon as formed unites with the alkaline bases to form urates. These are very soluble in warm water, but more sparingly so in cold. Therefore a urine, though clear when freshly passed and warm, may exhibit a copious precipitate upon becoming cold, as on a winter night This precipitate is easily recognized by its dis- PART III. — CLINICAL CHEMISTRY. 193 solving upon warming. Urates of sodium and magnesium gener- ally appear under under the microscope as amorphous powders in moss-like aggregations, but occasionally as bundles of small Fig. 52. Fig. 53. mm Uric acid. Uric acid. needles, as shown in Fig. 54. The urate of ammonium, a result of the alkaline fermentation, occurs as opaque, brown spherules, smooth or with spiculae like a thorn apple (Fig. 46). Fig. 54. Urates in bundles of small needles. Calcium oxalate. Uric acid, being dibasic, can form both normal and acid salts. If much acid is present in a urine, the normal urates give up one 194 ESSENTIALS OF CHEMISTRY. atom of their metallic base and become acid urates. These are less soluble than the normal, and often precipitate when the urine is very acid [see Fig. 45 (b)~\ or when an acid is added, as in the nitric acid test for albumin. The murexid test for uric acid and the urates is one of great beauty. Place some of the sediment in a porcelain dish, add a drop or two of nitric acid, and carefully evaporate almost to dry- ness. Add a few drops of ammonia; or, better still (Earp) in- vert the dish over another in which a dry ammonium salt is vola- tilized. If uric acid is present, a beautiful purple color will appear. Coloring Matters. — Our unsatisfactory knowledge of these substances and their clinical significance is to be regretted, since some of them possess an importance next to albumin and sugar. The existence of at least two distinct substances has been demonstrated : 1. Urobilin {Urohcematin) , a brown, resinous substance, de- rived from the coloring matter of the bile, and hence indirectly from the coloring matter of the blood. It occurs in normal urine, and in larger quantity in the urine of patients suffering from any disease which causes disintegration of the blood copuscles. 1. Uro-indican (uroxanthin) a substance closely related to, but not identical with, the glucoside indican, and, like that sub- stance, capable of conversion into indigo-blue. It seems to be derived from the indol formed in the fermentation of albuminous matters, especially in the alimentary canal. It is therefore in- creased in obstructive troubles and in certain diseases character- ized by decomposition of albuminoids or impairment and per- version of general nutrition; so that its presence is not patho- gnomonic of any one disease. To roughly estimate the coloring matters, put the urine in a beaker and render it strongly acid with nitric or hydrochloric acid. Let it stand six hours for the color to be developed. Then note the depth of color by transmitted light. PART III. CLINICAL CHEMTSTRY. 1 95 A striking method, especially for indican, is that of Jaffe. Take equal quantities of the urine and fuming HC1, and then add drop by drop with constant stirring, a fresh sat. sol. of calcium hypochlorite until the maximum of blue is produced. This is then shaken with chloroform, which seizes the freshly-formed indigo and soon settles to the bottom as a blue liquid, the depth of color indicating the amount of indican in the urine. Phosphates. — The phosphates are derived mainly from the food, but to some extent also from oxidation of phosphorized tissues : 1. Earthy Phosphates (Ca and Mg). — Being soluble only in acid solutions, the earthy phosphates are precipitated when the urine is made or becomes alkaline. Furthermore, being less sol- uble in warm than in cold urine, heat often precipitates them, as in the heat test for albumin. Deposits of calcium and magnesium phosphates are generally amorphous, and may be distinguished from the amorphous urates, (a) by absence of color and by not gathering in mossy forms j (a) • by a drop of acetic acid added to the sediment on a glass slide under the microscope — phos- phates dissolve, while urates gradually lose their base and assume the characteristic forms of uric acid. In ammoniacal urine (alkaline fermentation) the ammonio-magnesium phosphate (MgNH + P0 4 ), the so-called triple phosphate is formed and de- posited in large prismatic, coffin-lid crystals; sometimes also, in ragged stellate or aborescent crystals, resembling those of snow. (Fig. 55.) In cases of cystitis this may occur within the bladder ; hence other calculi often have one or more white layers of the mixed phosphate. 2. Alkaline Phosphates. — These constitute the greater portion of the phosphates, and are made up mainly of acid sodium phos- phate, with traces of potassium phosphate. Being very soluble, they never form a precipitate. Tests : (a) The earthy phosphates may be detected by the addition of any alkali e. g. liquor potassae, and gently warming. The normal amount produces only a whitish cloud, or opales- cence. 196 ESSENTIALS OF CHEMISTRY. (b) To detect and estimate the alkaline phosphates the pre- ceding should be filtered and the filtrate treated with magnesia mixture. U. S. P. 388 (V) The " total phosphates " are best detected and estimated Ammonio-magnesium Phosphate. by precipitation with the magnesia mixture. If the precipitate is thick and creamy, the phosphates are increased ; if milky, they are normal ; and if translucent, they are diminished. (a 7 ) Centrifugal Test. — Fill graduated tube to 10 Cc. mark with fresh urine ; add 5 Cc. of magnesia mixture, mix and then rotate for three minutes at the usual speed of one turn of the handle to the second. Normally the sediment should occupy ten per cent. Pathologically the phosphates are decreased in gout and most inflammatory diseases, especially in nephritis. This is a very valuable and almost constant symptom. They are increased in wasting diseases of the osseous and nervous systems and markedly so in the so-called " phosphatic diabetes," a disease attended by the various symptoms of denutrition. Chlorides. — These, normally about 15 Gm. a day, consist 388 Magnesia Mixture, U. S. P. Magnes. Sulph., 10 Gm.; Ammon. Chlor- ide, 20 Gm.; Water, 80 Cc; Ammonia water, 42 Cc. PART III. CLINICAL CHEMISTRY. 197 almost entirely of sodium chloride, the quantity depending mainly on what is taken in with the food. However, in many fevers, especially in pneumonia, the chlorides may be diminished in the urine or may even disappear from it, much being eliminated by sputa. Their reappearance in the urine is often the earliest indi- cation of convalescence. Hence their detection and estimation are important. Silver-Nitrate Test, — First add a few drops of nitric acid to prevent the precipitation of the phosphates. Then, on adding silver-nitrate solution (i to 500), the chlorides will fail as a white precipitate of silver chloride. If the precipitate is in curdy masses, the chlorides are not diminished ; if only a milkiness is produced, they are greatly diminished ; and if no cloudiness, they are entirely absent. Centrifugal Test. — To 10 Cc. of the urine in the graduated tube add a few drops of nitric acid and fill to the 15 Cc. mark with a solution of silver nitrate (1 to 500), mix and then rotate as in the preceding. The amount, if normal, should occupy about 15 per cent. Sulphates. — These consist mainly of sodium sulphate, with a little of the potassium salt. They are derived principally from the food and in small quantity from oxidation of albuminoid sul- phurized tissues, especially in fevers. Tests. — {a) Barium Test. — First add a few drops of nitric or hydrochloric acid to hold the phosphate in solution ; then add barium chloride test-solution U. S. P. (12.2 per cent.) until pre- cipitation is complete. If the precipitate is creamy, the sulphates are increased ; if milky, normal , and if only opalescent, dimin- ished. (b) Centrifugal Test. — To 10 Cc. of urine add a few drops of nitric acid and fill up to the 15 Cc. mark with the barium chloride test-solution ; after rotation the volume of the precipitate is nor- mally one per cent. 198 ESSENTIALS OF CHEMISTRY. Abnormal Urine. Urine may be abnormal from excess or diminution of the fore- going normal constituents or from the presence of various sub- stances that are never found in healthy urine. Of these, the most important are the proteids, namely, albumin, globulin, albumose and peptone. Albumin. — By this is generally meant serum albumin which, it not being osmotic, appears in the urine only in pathological con- ditions and in certain functional disturbances, due to abnormal difTusibility of the blood's albumin or to excessive blood pressure in the kidneys, or oftenest, to lesions in the renal tissues them- selves. Heat Test. — A test-tube is one -third filled with the suspected urine and held in the flame of a spirit-lamp, or over the chimney of an ordinary lamp, until it boils. If an opacity occurs, it must be either atbumin or earthy phosphates. If earthy phosphates, it clears up on addition of nitric acid, but if albumin, it is slightly increased. Nitric Acid Test. — This consists in under-laying the urine with nitric acid. Take a test-tube one-fourth full, and, holding it aslant, gently pour in an equal volume of the acid, allowing it to trickle down the inside of the tube and pass beneath the urine. Or, the acid may be put in first and the urine added afterward. Howe's method of applying this test is : Pour about 5 Cc. of the urine into a test-tube and warm it to about ioo° F. Through a funnel pipette, reaching to the bottom of the test-tube, add an equal volume of nitric acid. If albumin is present, there will ap- pear at the junction of the two liquids a narrow white band, best seen in a strong light, against a black back-ground. An opacity at the junction of the two liquids is either albumin or urates. Ifurates, it clears up on heating, but if albumin, it is permanent. Either the heat or nitric acid test, singly, is unsatis- factory, but both performed together are conclusive. However, the following sources of error should be borne in mind : (a) if the urine is very alkaline and the quantity of albumin small, heat PART III. CLINICAL CHEMISTRY. 1 99 will cause no opacity ; (b) If only a drop or two of nitric acid be added, the acid may hold a small quantity of albumin in solution ; (V) urea may be precipitated from a concentrated urine by nitric acid, but heat dissolves it; (d) decomposed urines, containing, as they do, ammonium carbonate, effervesce on addition of an acid; ( Iro- Creamo- :er. meter. (Starr.) Feser's Lactoscope. (Queen.) Skim milk, however, may be so diluted as to bring its specific gravity within the ordinary limits, but an experienced eye can readily see that instead of being white, the milk assumes a bluish tinge, or in other words loses the natural opacity imparted by the suspended oil globules. So the measurements of the specific 402 Let the student dilute a specimen of milk in a test-tube or beaker, and note the bluish tint produced. 2 22 ESSENTIALS OF CHEMISTRY. gravity are not conclusive unless the opacity be also observed : This is easily done by the lactoscope (Fig. 7o), 40H which consists of a cylinder of clear glass (A), containing at the lower part a smaller cylinder of white glass (resembling that shown at x, fig. 70), upon which are a few black lines. In testing, 4 Cc. of the milk are intro- duced from the graduated pipette {B)^ and the black lines are en- tirely concealed by the opaque milk ; pure water is then gradually added with shaking until the milk is clear enough for the black lines to be visible. The level of the diluted milk in the cylinder is then read off in the graduations as percentage of fat in the original sam- ple. This method is quick, accurate and reliable, unless the milk be adulterated with some suspended white powder, as chalk or starch, in which case the microscope will disclose its nature. A simple but rough estimate of the cream may be made by allowing the milk to stand over night in a graduated cylinder such as the creamometer shown in Fig. 69. 404 "Wit centrifuge (Figs. 71 and 72) with milk-tubes and a volume- pipette (Fig. 73) affords a very quick and fairly accurate method of estimating the quantity of fats. Add to each milk-tube 5 Cc. of the milk, 1 Cc. of the HC1 solution (hydrochloric acid, 50 vol- umes ; methyl alcohol, 13 volumes ; fusel oil, 37 volumes) ; shake well and add strong sulphuric acid (sp. gr. 1.83) drop by drop with constant shaking until tube is filled to the zero mark. Ro- tate for two minutes and read the percentage of fats directly from the scale. As the graduations extend only to 5 per cent., a milk richer than this must be diluted, and the reading multiplied ac- cording to the dilution. The above methods of estimating the amount of fat, although very useful, are not sufficiently reliable and accurate for official inspection. Milk may vary in consistence as well as in composi- tion, so that one specimen may furnish more cream than another 40i The teacher should show actual work with a creamometer and lactoscope. 404 Let each student chew a piece of paraffine and collect the saliva in a beaker. PART III. — CLINICAL CHEMISTRY. 223 containing twice as much fat. For accurate work, the Werner- Schmidt process is very convenient, viz., take 10 Cc. of the milk and 10 Cc. of strong HO ; pour into a long test-tube of about 50 Cc. capacity. Bring the mixture to a boil ; when cool add 10 Cc. of ether and shake well ; as soon as the ether has all risen to Fig. 71. Fig. 72. Fig. 74. fi=* If Fig. 73. the top, remove the cork and insert the perforated cork and tube, as shown in figure 74. By sliding the exit tube down until it opens just above the line of separation, the ether solution of the fat can be blown into a previously weighed beaker ; another portion of ether is added to the test-tube, shaken and blown out as before, repeating the pro- cess two or three times. The ethereal solution is now evaporated over a water-bath and the beaker weighed. The amount of fat thus obtained represents that contained in 10 Cc. of milk and shows the percentage. 224 ESSENTIALS OF CHEMISTRY. Clinical Test of breast milk is generally neglected by the prac- titioner, though it has been long recognized that the milk of dif- ferent women, or even of the same woman under different condi- tions, health, diet, exercise, etc., often disagrees with the nursling. Dr. Emmet Holt, of New York, who has made extensive studies along this line, has shown that these clinical variations are attended by, and possibly caused by, variations of specific gravity, reaction and percentage composition. The specific gravity of human milk should range from 1028 to 1033 and the quantity cream from 3 to 4 per cent. Kumyss is the name given to milk fermented under the influ- ence of a peculiar ferment, originally imported from Southern Russia. The lactose is made to undergo the vinous fermentation, producing alcohol and carbon dioxide in the presence of the yeast plant. It is a valuable stimulant and food stuff in malnu- trition and wasting diseases. SALIVA. Human saliva is a viscid, tasteless, opalescent, alkaline fluid, the product of the salivary glands. 404 Its active principle is pty aline, the function of which is to convert starches into glucose. 405 It acts best in neutral reaction \ strong alkalies or acids retard or even destroy it. Saliva also contains potassium sulpho-cyanate, 406, the function of which is unknown. 405 Put some saliva with a few drops of starch solution in four test-tubes and label a, b, c and d. To a add two drops of HC1; to b five drops of liquor potassse; boil c. Set all four test-tubes in a beaker of water; warm no hotter than the hand can easily bear. After ten minutes remove and test each tube for starch and sugar. It will be found that only in d has the ptyaline con • verted the starch into glucose, for acids and alkalies restrain the ptyaline, and boiling destroys it. 406 To some saliva in a test-tube add a drop of ferric chloride, a blood-red color indicates potassium sulpho-cyanate. PART III. CLINICAL CHEMISTRY. 225 GASTRIC JUICE. Gastric juice is a thin, yellowish, sour licruid, of specific gravity seldom over ioio, and of somewhat variable composition. It may be obtained fairly pure from man and other animals, through gas- tric fistulae or more usually the stomach-pump, or stomach-tube. It is secreted and reabsorbed in surprising quantity, a man pro- ducing from fifteen to thirty pounds a day. Its composition may be stated as Water 99-44 Pepsin and other organic matter 32 Hydrochloric acid 25 Sodium chloride 14 Potassium chloride 05 Calcium chloride 006 Calcium and magnesium phosphates 015 100.221 Pepsin is a ferment that in connection with acids has the prop- erty of converting, by a process of hydration, the albuminoids into albumoses and finally into peptones, making them osmotic and capable of being taken up by the vessels of the stomach. It digests only nitrogenous food, the oils, fats, starches and sugars being unaffected by it. The process is retarded by too little or too much acid and by alcohol. The pepsin does not seem to be destroyed in the process, but continues to act almost indefinitely, digesting large quantities of the proteids. Its acidity is due mainly to hydrochloric and certain organic acids, as lactic, butyric and acetic, but these latter are incidental and mainly the result of fermentative action. Clinical examination of gastric juice is becoming each year a more and more important means of diagnosis in stomach diseases. The usual method is, first to thoroughly wash out the stomach with warm water and, some hours afterward, administer a test- meal. This is usually a light breakfast consisting of an ounce and a-half of dry roll and eight ounces of water, or weak tea 2 26 ESSENTIALS OF CHEMISTRY. without milk or sugar. To insure thorough mastication and sali- vation twenty minutes should be occupied in consuming the meal, and the water or tea stfould be drunk last. One hour afterwards, the secretion of HCl (one of the two chief agents in proteid di- gestion) being at its maximum, the remains of the liquefied food are drawn off and examined, first ocularly to determine the degree of disintegration and solution. Normally, all of the nine and one- half ounces of the test-breakfast, with the exception of one and one-third ounces, should be absorbed, or passed into the small intestines at the end of an hour. If a larger amount is found it indicates slow absorption ; if a smaller, more rapid absorption than normal. The stomach contents, light yellow in color, are then filtered, and the filtrate examined according to the following scheme : Filtrate of stomach contents after a test-bteakfast. Color clear yellow. Qualitative Tests. — (i) Litmus test— 7 reaction acid (red). (2) Free acid, Congo-red, test — very delicate, reaction blue. (3) Free HCl, Gunzburg's test, Boas's test — reaction car- mine red. (4) Lactic acid, Uffelman's test — reaction greenish yellow. (5) Rennet ferment, Milk test — coagulation. (6) Butyric acid — decolorizes Uffelman's reagent. ( 7) Acetic acid, odor test. Quantitative Tests. — (8) Estimation of total acidity by saturation. (9) Esti?nation of free HCl by Leo's method. (10) Estimation of acid salts by Leo's method. ( 1 ) Litmus test. — Tested with litmus paper, the reaction should be acid, turning the paper red. (2) Congo-red test. — Add a few drops of this dye to a portion of the stomach fluid. Free acids if present change it to sky-blue j acid salts produce no change. PART III. — CLINICAL CHEMISTRY. 2 2^ (3) Free HCL — To determine the presence or absence of this is of great importance to the physician, as it is as necessary for digestion as the pepsin itself, and its variation more important in diagnosis, e. g., between cancer, in which it is diminished, and gastric ulcer, in which it is increased. r Phloroglucin . . 2 gr. (a) Gunzburg's reagent 1 Vanillin .... 1 gr. (.Absolute alcohol . 30 gr. A drop of this solution is added to a few drops of gastric juice and gently warmed. If free HC1 be present in the smallest amount a red color is produced, and cherry-red crystals de- posited. c Resorcin (resublimed) . . 5 gr. (b) Boas's reagent -j Sacchar. alb 3 gr. L Spiritus dilut 100 gr. This test is about as delicate as the preceding and its ingre- dients not so rare and expensive. A few drops of the solution added to a little gastric juice in a dish and gently warmed pro- duces a red color if free HC1 be present. 4. Uffelman's test. — Add to 5 or 10 Cc. of a 2 to 5 per cent, solution of carbolic acid, 1 or 2 drops of ferric chloride solution and dilute with water till the solution assumes a beautiful amethyst-blue color ; to this add a portion of the stomach fluid ; a change to canary or greenish-yellow indicates lactic acid. This test is extremely delicate, holding for a 1 in 20,000 solution of lactic acid. Be careful to ascertain whether the patient has taken any wine or alcohol preceding the test, as either of these will give the same reaction. (5) Rennet ferment, milk test. — Take a small quantity of boiled milk, say 10 Cc, having a neutral reaction, and add an equal amount of carefully neutralized filtered stomach contents. The mixture is then placed in a warm chamber at 100 F., and in 10 or 15 minutes the milk has coagulated and separated into a cake of casein and clear whey. 2 28 ESSENTIALS OF CHEMISTRY. (6) Butyric acid decolorizes Uffelman's reagent. If present in large quantities, its acrid, rancid odor is manifest. (7) Acetic acid. — The best practical test for this acid also is the nose. If present in considerable quantity it has an unmistak- able odor. (8) Total acidity. — The method of measuring this is simple. A burette is filled with a decinormal solution of caustic soda : 5 or 10 Cc. of filtered stomach contents are poured into a small glass beaker, and 1 or 2 drops of a (1 per cent.) alcohol solution of phenol-phthalein are added. The solution in the burette is very gradually added until the red color is just permanent. The number of Cc. of the alkaline solution used represents the acidity of the quantity of stomach contents employed. Normally the acidity of 10 Cc. of the stomach contents, obtained one hour after the test breakfast, is from 4 to 6 Cc. ; results below or above this are pathological. (9) Estimation of free HC/.—This, provided no other free acids are present, is determined by adding pure chalk, which will neutralize the acidity if due to free acid, but has no effect on acid salts. The difference in acidity before and after the addition of the chalk represents the physiologically active HC1. To separate the organic acids, first extract with ether, by thoroughly shaking about 5 to 10 Cc. of the stomach contents in a medicine bottle with alcohol-free ether ; let the ether separate, which usually occurs very rapidly, and pour off in a small glass beaker. This is repeated until about 30 to 60 Cc. of ether has been used. The ethereal extract contains the organic acids. (10) Acid Salts. — The last determination of acidity in the pre- ceding test represents the quantitative estimate of acid salts. PART III. CLINICAL CHEMISTRY. 229 FERMENTS. — These are certain nitrogenous bodies, animal and vegetable, of unknown constitution, which by some means, not clearly understood, cause many organic compounds to decompose, with the production of other and simpler substances, the ferments themselves being unaffected. Ferments are of two classes : Organized and Unorganized Ferments. 1. The Unorganized or Soluble Ferments. — Among these are: (a) diastase or malti?i, appearing in the sprouting of grain, and formed from the gluten; it serves to convert the starch of the seed into glucose. Malt, which is sprouted barley, contains it in abundance, and is used to convert meal (starch) into glucose for fermentation in the manufacture of alcoholic liquors, and in medicine as a digestive agent. The ptyalin of saliva and a pancreatic ferment act like diastase, (b) pepsin, of the gastric juice, and (c) trypsin, of the pancreatic fluid, both of which serve to convert the albuminoids into pep- tones, the one in acid and the other in alkaline solution. Fig. 75. YEAST CELLS. 2. Organized Ferments. — When their spores are carried by the atmos- phere, or otherwise, into a suitable fermentable liquid, viz., one containing albuminoid substance, and kept warm (68 to 105 F.), these ferments grow and proliferate wiih great rapidity, inducing fermentative changes in a few hours. The most important of these ferments are : (a) Yeast (torula cerevisice, or saccharomyces eerevisice), shown in figure t>&- This converts glucose into alcohol and carbon dioxide (vinous fermentation); (b) acetic acid fer?nent (ijiycoderma aceti), commonly called " mother of vinegar," grows on solutions containing alcohol, which it helps to oxidize into acetic acid; (c) mucor mucedo, which causes alcoholic fermentation; (d) thrush fungtis (oidium albicans) grows within the mouths of ill-kept children. It induces a slight alcoholic fermentation; (e) lactic and butyric ferments go together, the one preceding and the other closely following. These fermentations occur in intestinal indigestion, and the gas evolved produces flatulent colic. Putrefaction (the spontaneous decomposition of nitrogenous organized bodies) is accompanied, if not caused by micro-organisms, usually bacteria. Decay, on the other hand, is the gradual decomposition of organic bodies by the slow action ot oxygen, and does not depend on living organisms. Fer?nentation Experime7it. — Before leaving the laboratory exercise, make a mixture of thin starch paste, crushed malt grains, and a bit of yeast. Put into a side-necked test-tube with its mouth corked, and the delivery tube dipping into a bottle of lime water. Next day note that the mixture has fermented, or is fermenting, and that the CO., evolved has bubbled out through the lime water, precipitating CaC0 3 , and that the mixture is now alcoholic. 230 ESSENTIALS OF CHEMISTRY. TABLE OF METRIC MEASURES. Fig. 76. pm IIIII1II I HI tlll[lt-||ltlM!ll|IMIIIllll. i |tll l |llll| l ll i| iiii |ii iijjiii|jiij| mum w 10 The Decimetre. MEASURES OF LENGTH. Millimetre Centimetre Decimetre Hetre Decametre Hectometre Kilometre Myriametre = 0.001 of a metre. = 0.010 of a metre. = 0.100 of a metre = 1.000 Hetre = 10.000 metres. = 100,000 metres. = 1000.000 metres = 10,000.000 metres = about 4 inches. = 39.37 inches. = about % of a mile. = about 6% miles. Centaire Are Hectare MEASURES OF SURFACE. 1 square metre = about i£ square yards 100 Square Metres. 10,000 Square metres. = about 2%, acres. MEASURES OF VOLUME. Cubic centimetre = 0.001 of a litre. Litre (cubic decimetre) = 1000. cubic centimetres. Cubic metre = 1000. cubic decimetres. Cubic metre = tooo. litres, or 1 kilometre. Cubic metre = 1 stere. MEASURES OF WEIGHT. 1 Milligramme = 0.001 of a gramme = about -Q-g of a grain. 1 Centigramme = 0.010 of a gramme. 1 Decigramme = o. too of a gramme. 1 Gramme = 1.030 Gramme = about 15% grains. 1 Decagramme = 10.000 grammes. 1 Hectogramme — 100 000 grammes. 1 Kilo(gramme) == 1000.000 grammes = about 2! lbs. 1 Tonneau = ic kilos = about 1 ton. INDEX. Absolute weight, 10 Acetamide, 170 Acetanilide, 171 Acetic aldehyde, 152 Acetone, 145, 205 Acetylene, 100, 139 Acid, acetic, 153, 228 antimonic, 70 antimonious, 70 arsenic, 63 arsenous, 64 benzoic, 161 boric or boracic, 107 butyric, 154, 228 cathartic, 169 carbazotic, 161 carbolic, 159 carbonic, 75 chloric, 41 chlorous, 41 chromic, no citric, 158 cyanic, 80 diacetic, 205 diatomic, 157 diabasic, 157 formic, 145, 153 gallic, 162 hippuric, 192, 206 hydriodic, 41 hydrobromic, 41 hydrochloric, 41 hydrocyanic, 41 hydroferri cyanic, 80 hydroferrocyanic, 80 hydrofluoric, 41 hydrosulphuric, 46 hypochlorous, 41 hyponitrous, 57 hypophosphorous, 63 lactic, 158, 219 lithic see Uric), 192 malic, 158 mecomic, 179 metaphosphoric, 62 muriatic, 41 myronic, 169 nitric, 59 nitrohydrochloric, 41 nitromuriatic, 43, 128 nitrous, 58 oleic, 155 orthophosphoric, 63 osmic, 129 oxalic, 157 palmitic, 155 Acid, pentylic, 154 perchloric, 41 phenic, 159 phenvlic, 159 phosphoric, 63 phosphorous, 63 picric, 161 prussic, 79 pyrogallic, 162 pyrophosphoric, 62 salicylic, 162 silicic, 81 sodium phosphate, 90 , 185, 195 stearic, 155 succinic, 158 sulphocarbolic, 160 sulphocyanic, 80 sulphuric, 50 sulphurous, 49 tannic, 169 tartaric, 158 tetrylic, 154 uric, 192 valerianic, 154 xanthoproteic, 172 Acidimetry, 96 Acid salts, 91 Acids, aromatic, 161 definition of, 40 fatty, 154 organic, 153 Aconitine, 179 Affinity, chemical, 32 precedence of, 32 Agate, 81 " Aging " of liquors, 147 Air, S3, 77 Albumin, 198 acid, 174 alkali, 174 derived, 174 egg, 173 serum, 173 vegetable, 173 Albuminates, 174 Albumins, natural, 173 Albumoses, 175, 200 Alcohol, 144 absolute, 146 amylic, 148 butyl, T48 derivatives, 144 ethene, 157 ethyl, 146 glyceryl, 159 methyl, 145 (*3') 232 INDEX. Alcohol, pentyl, 148 propyl, 148 radicals, 157 sulphur, 148 tetryl, 148 trityl, 148 vinic, 146 wood, 145 Aldehyde, 152 acetic, 152 ethyl, 152 form-, 152 par-, 152 Aldehydes, 145, 151 Ale, 147 Algaroth, powder of, 70 Alkalies, organic, 175 Alkalimetry, 96 Alkaloids, 175 Allantoin, 192 Alloys, 82 Allotropic forms, 81 Allylsulphocyanate, 168 Allotropism, 137 Aluminum, 107 chloride, 108 group, 106 hydrate, 108 oxide, 108 silicates, 109 sulphate, 108 Alum, 108 Alumen, 108 exsiccatum, 109 Amalgam, 82, 121 Amber, 158 Amethyst, 81 Amides, 169, 175 Amines, 169, 175 Ammonia, 55 fountain, 56 liquefied, 56 type, 169 Ammoniac, 141 Ammoniated mercury, 123 Ammonii carbonas, 88 Ammonio-citrate of iron, 117 ferric alum, 109 magnesium phosphate, 103, 195 nitrate of silver, 66 sulphate of copper, 66 tartrate of iron, 66 Ammonium, 87 bicarbonate, 88 carbonate, 88 cyanate, 80, 133, 188 hydrate, 87 hydrosulphide, 88 molybdate, 118 nitrate, 58, 87 nitrite, 53 Amygdalin, 80, 168 Amy! acetate, 154 hydrate, 148 nitrite, 151 Amyl alcohol, 148 Amyloses, 163 Amylum, 164 Analysis, 26 acidulous radicals, 131 definition of, 26 metallic radicals, 130 ultimate, 135 Aniline, 170 Animal charcoal, 74 Antifebrin, 171 Antimonious chloride, 69 hydride, 69 •oxychloride, 70 oxide, 70 sulphide, 70 Antimoniuretted hydrogen, 69 Antimony, 69 Antimony and potassium tartrate, 70 Antimony, butter of, 69 Antimonyl, 70 Antipyrine, 171 Antiseptics, 54 Antitoxine, 178 Antizymotics, 54 Anuria, 182 Apomorphine, 179 Aqua, 26, 87 ammonia, 87 ammoniae fortior, 38 chlori, 38 destillata, 30 fortis, 59 regia, 43, 128 Arbutin, 169 Archimedes, principle of, n Argenti nitras, 126 Argol, 158 Argon, 55 Arsenic, 63 oxide, 65 pentoxide, 65 toxicology of, 65 white, 64 Arsenical mixtures, 66 poisoning, 66 Arsenous hydride, 64 iodide, 64 oxide, 64 sulphide, 64 Arseniuretted hydrogen, 64 Arsenum, 63 oxides and acids, 64 Arsine, 64 Artificial parchment, 163 products, 133 Assafoetida, 141 Asbestos, 81, 102 " -ate," 36 Atmosphere, 53 Atomic theory, 15 • weight, 16 Atoms, 16 Atropine, 179 Auric chloride, 129 Auri et sodii chloridum, 129 Babbitt's metal, 69 Bacillus acidi lactis, 220 cyanogenus, 220 INDEX. 2 33 Bacteria, 214 Bacterial proteids, 178 Baking powders, 90 Baking soda, 90 Balloons, 20 Balsam of Peru, 141 Balsams, 141 Barium, 101 chromate, 102 sulphate, 101 Bases, 18 Basylous radicals, 32 Beer, 147 Beet sugar, 166 Bengal light, 101 Benzaldehyde, 168 Benzene, 142 series, 141 Benzine, 138 Benzoin, 141 Bichloride of mercury, 123 Bichromates, in Bile in urine, 206 Bilirubin, 206 Bismuth, 71 ammonio-citrate, 72 nitrate, 71 oxynitrate, 71 subcarbonate, 71 subnitrate, 71 Bismuthyl, 70 Biuret reaction, 172, 201 Black lead, 73 oxide of copper, 119 oxide of manganese. 21, 38, in oxide of mercury, 124 Black wash, 124 Bleaching, 31, 39, 90 powder, 99 Blondine, 31 Blood, 208 Blood casts in urine, 212 Blue ointment, 121 pill. 121 vitriol, 119 Bluestone, 119 Boas' reagent, 227 Boiling point of water, 26 Boroglyceride, 107 Borax, 107 Boron, 106 Brandt, 60 Brandy, 147 Brass, 104 Brazing, 107 Brimstone, 45 Britannia metal, 69 British gum, 164 Bromides, test for, 43 Bromine, 37, 136 Bromoform, 143 Bromum, 37, 136 Bronze, 118 Brucine, 179 Burette, 97 Butter, 219 of antimony, 69 Butyl, 144 Cadaverine, 178 Cadmium, 106 Caesium, 96 Caffeine, 179 Calcined magnesia, 103 Calcium, 98 carbide, 10c, 140 carbonate, 98, 206 chloride, 98 group, 97 hydrate, 99 hypochlorite, 99 oxalate, 99, 205 oxide, 98 phosphate, 99 sulphate, 99 Calculi, urinary, 205, 215 Calomel, 123 Calx, 98 chlorata, 99 Camphor, coal tar, 142 monobromated, 141 Camphors, 140, 141 Cane sugar, 166 Caoutchouc, 141 Caramel, 165 Carat fine, 128 Carbamide, 170, 188 Carbohydrates, 163 Carbon, 73, 133, 135 dioxide, 75 disulphide, 48 group, 72 monoxide, 74 Carbonates, 76 Carburetted hydrogen, heavy, 139 Casein, 174, 218 Caseinogen, 218 Cast-iron, 113 Casts, 212 Catalysis, 34 Caustic ammonia, 87 potash, 92 Cellulin, 163 Celluloid, 164 Cellulose, 163 Centrifuge, 181, 196, 197, 200, 213, 222 Cerium, 109 Chalcedony, 81 Chalk, 98 Chalybeate water, 29, 116 Charcoal, 73 animal, 74 Chemical action, 9 affinity, 32 Chemistry, definition of, 9 inorganic, 18 organic, 133 Chloral, 252 butylicum, 153 croton, 153 hydrate, 152 Chloralum, 108 Chloric ether, 150 Chloride of gold, 29 of lime, 99 Chlorides in urine, 196 Chlorides, test for, 43, 196 234 INDEX. Chlorinated lime, 99 Chlorophyl, 77 Chlorine, 37, 99, 136 group, 37 oxides, 41 oxysalts, 43 water, 38 Chloroform, 142 Choke-damp, 75 Chromates, no Chrome-yellow, 85 Chromic, oxide, no salts, in Chromium, no trioxide. no Chyluri.i, 182, 210 Cider, 147 Cinchona alkaloids, 179 Cinchonicine, 179 Cinchonidine, 179 Cinchonine, 179 Cinnabar, 124 Citrine ointment, 122 Clabber, 220 Classification of elements, 18 Clay, 81, 109 Coal, 73 mineral, 73 Coal-tar camphor, 142 Cobalt, 117 Cocaine, 179 Codeine, 179 Colchicine, 179 Cold, production of, 14, 76 Coline, 177 Collodion, 164 flexible, 164 styptic, 164 Colocynthin, 169 Cologne, 140 Coloring matters, urinary, 183, 194 Colostrum, 216 Columbium, 52 Combining weight, 16 Combustible, 22 Combustion, 22 supporter of, 22 Compounds, 14 Concentrated lye, 91 Conine, 179 Copal, 141 Copper, 118 ammonio-sulphate, 66 arsenite, 66 black oxide, 119 group, 118 suboxide, 120 Copperas, 114 Corals, 89 Corundum, 108 Corrosive sublimate, 123 Cotton, 163 Cow's milk, 219 Crab Orchard salts, 102 Cream, 222 of tartar, 92 Creamometer, 222 Creasote, 160 Creatine, 178, 192 Creatinine, 178, 192 Cresol, 161 Creta preparata, 98 Croton chloral, 153 Crystallin, 174 Crystallization, water of, 27 Cupric hydrate, 119 oxide, 119 subacetate, 120 sulphate, 119 CuprOus oxide, 120 Curding, 155 Cyanates, 80 Cyanide, mercuric, 79 Cyanides, compound, 80 Cyanogen, 79 Cymogene, 138 Cystin, 208 Davy's method, 190 Decantation, 98 Decay, 229 Decone, 140 Deliquescence, 27 Deodorizers, 54 Destructive distillation, 26 Developer, 128 Dewar, 20 Dew-point, 54 Dextrin, 165 Diabetic sugar, 167, 201 urine, 201 Dialyzed iron, 116 Dialyzer, 116 Diamond, 73 Diastase, 229 Diethylamine, 178 Diffusion, 78 gases, 78 Digitalin, 169 Disinfectants, 54 Distillation, 30 destructive, 26 fractional, 30 Donne's test, 209 Donovan's solution, 64 Doremus' method, 191 Draught in ventilation, 78 Drummond light, 20 Dynamite, 159 Earthenware, 109 Earths, metals of the, 106 Earthy phosphates, 182, 195 Efflorescence, 27 Elastica, 141 Elaterin, 168 Electrolysis, 26, 32 Electro-positive and negative, 32 Elements, 14 classification of, 18 cable of, 15 Empirical formulae, 137 Emplastrum plumbi, 83 Emery, 108 Emulsin, 168 Epithelial casts, 211 INDEX. 235 Epithelium, 210 Epsom salts, 102 Equation, 17 Erbium, 106 Esbach's albuminometer, 199 Eserine, 179 Essence of pear, 148 artificial, 148 Essential oils, 140 Estimation of free HC1, 228 Etching, 42 Ethane, 139 Ethene, 139 alcohol, 157 Ethine, 139 Ether, 149 butyric, 219 chloric, 150 ethyl, 149 hydrobromic, 151 hydrochloric, 150 nitrous, 151 ozonized, 31 sulphuric, 149 Ethers, compound, 145, 149 mixed, 149 simple, 145, 149 Ethyl, alcohol, 146 aldehyde, 152 bromide, 151 chloride, 150 hydrate, 144 mercaptan, 149 nitrite, 151 oxide, 149 Ethylamine, 178 Eudiometer, 26 Evaporation, 14 Extraneous bodies in urine, 215 Fat, 219 in urine, 210 Fats, 155 Fatty casts, 212 Fehling's test, 202 solution, 202 Feldspar, 109 Ferments, 229 Ferri citras, 117 carbonas saccharatus, 116 et ammonii citras, 117 et ammonii tartras, 117 et potassii tartras, 117 et quininae citras, 117 et strychniae citras, 117 pyrophosphas, 117 Ferric chloride, 114 hydrate, 115 nitrate, 116 sulphate, 114 Ferricyanides, 80 Ferricyanogen. 80 Ferrocyanogen, 80 Ferrous chloride, 114 carbonate, 116 hydrate, 115 iodide, 116 sulphate, 114 Ferrous sulphide, 116 Ferrum redactum, 113 Fibrin, 175 Fibrinogen, 174, 175 Fibrinoplastin, 175 Filtration, 98 Fire-damp, 139 Fixed oils, 154 Flashing point, 138 Flint, 81 Flowers of sulphur, 45 Fluid, definition of, 14 Fluorides, tests for, 45 Fluorine, 37 Fluorspar, 38 Flystone, 117 Formaldehyde, 152 Formulas, 17, 137 molecular, 136 Fowlers method for urea, 191 solution, 65 Fractional distillation, 30 Fruit essences, artificial, 148 Fungi, 182 Fusel oil, 148 Galena, 82 Galls, oak, 161 Galvanized iron, 104 Gas, definition of, 13 illuminating, 75, 139 laughing, 58 marsh, 139 natural, 139 Gasoline, 138 Gastric juice, 225 composition of, 225 Gentianin, 169 German silver, 117 Germicides, 54 Giant powder, 159 Glass, 81 Glauber's salt, 90 Globulin, 173, 200 Glucose, 167. 201 Glucosides, 168 Ghitin, 175 Gtycerine, 159 Glvcerites, 159 Glycerol, 159 Glyceryl, 158 Glycol, 157 Glycyrrhizin, 169 Glyceryl alcohol, 159 Glycogen, 166 Gold cures. 129 leaf, 128 Goulard's extract, 84 Gout, 192 Granite, 109 Grape sugar, 167. 201 Graphite, 73 Gravity, specific, 10 Gray powder, 121 Greek numerals, 41 Green fire, 101 Green vitriol, 114 Groups of the elements, 18 236 INDEX. Guaiacol, 160 carbonate, 160 Gum-resins, 141 Gums, 164 Gun cotton, 163 Gun powder, 94 Gunzburg's reagent, 227 Guttapercha, 141 Gypsum, 99 Hsematuria, 208 Haines' test, 202 Hair dye, 127 Hartshorn, 55 spirits of, 55 Heavy carburetted hydrogen, 139 Helium, 55 Heteroxanthine, 178 Holt, Dr. L. Emmet, 224 Homatropine, 179 Homologous series, 134 Howe's method, 198 Hydracids, 40 Hydrates, 26 Hydrargyri, chloridum mite, 123 iodidum flavum, 122 iodidum rubrum, 122 viride, 122 oxidum flavum, 124 oxidum rubrum, 124 subsulphas flavus, 123 Hydrargyrum, 121 cum creta, 121 Hydrobromic ether, 157 Hydrocarbons, 137 Hydrochloric ether, 150 Hydrogen, 19 antimonide, 69 arsenide, 64 carburetted, 139 cyanide, 79 dioxide, 30 monoxide, 25 -oxide, 25 peroxide, 30, 208 sulphide, 46 Hydroxybenzene, 159 Hyoscyamine, 179 Hydrometer, n Hyoscine, 179 " Hypo-," 36 Hyposulphite of sodium, 49 Hyposulphites, 49 Hypoxanthine, 178 " ic," 41 Ice, 25 " ide," 36 Ignis fatuus, 61 Illuminating gas, 75 Indestructibility, 10 India rubber, 141 Indican, 169, 194 Indicators, 97 Indol, 169 Ink, 169 black, 116 Ink, indelible, 127 sympathetic, 117 Inorganic chemistry, 18 Insolubility, influence of, 33 Iodide of nitrogen, 53 of starch, 39, 163 Iodides, test for, 43 Iodine, 37, 136 Iodoform, 144 Iridium, 129 Ironj 112 age, ir8 by hydrogen, 113 cast, 113 dialyzed, 116 galvanized, 104 group, no Pig,, it 3 pyrites, 116 Quevenne's, 113 reduced, 113 salts (see Ferrous and Ferric), 114 scale, compounds of, 116 specific gravity of, 12 wrought, 118 Isoamylamine, 177 Isologous series, 134 Isomerism, 137 "ite," 3 6 Jalapin, 169 Javelle water, 95 Kalium, 90 Kaolin, 109 Kerosene, 138 Ketone, 145 Kolbe, 133 Konig, 218 Kreatine, 178, 192 Kreatinine, 178, 192 Krypton, 55 Kumyss, 224 Labarraque's solution, 95 Lac sulphuris, 45 Lactometer, n Lactoscope, 222 Lactose, 219 Lsevulose, 168 Lamp black, 74^ Lana philosophica, 104 Lanthanum, 106 Laughing gas, 58 Lardacein, 175 Larrabee, 27 Leachins:, 94 Lead, 82 acetate, 83 carbonate, 84 chloride, 84 chromate, 85 dioxide, 83 iodide, 85 nitrate, 83 oxide, 83 plaster, 83, 155 INDEX. 237 Lead, puce, 83 red, 83 subacetate, 84 sugar of, 83 sulphate, 84 sulphide, 85 water, 84 white, 84 Ledoyen's disinfectant fluid, 83 Leffmann, 187 Legumin, 174 Leucin, 208 LeucomaVnes, 178 Licorice, 169 Lieben's test, 205 Lignin, 163 Lime (see Calcium) , 98 chlorinated, 99 kilns, 98 quick, 98 slaked, 99 water, 99 Limestone, 98 magnesian, 102 Linen, 163 Linseed oil, 155 Liquid, definition of, 13 Liquor, 26, 87 acidi arsenosi, 65 arseni et hydrargyri iodidi, 64 calcis. 99 saccharatus, 99 definition of, 26 ferri chloridi, 114 nitratis, 116 subsulpl atis, 115 tersulphatis, 115 gutta-perchae, 141 hydrargyri nitratis, 122 iodi compositus, 39 magnesii citratis, 103 plumbi subacetatis. 84 potassae, 93 potassii arsenitis, 65 Liter flask, 97 Litharge, 83 Lithium, 86 urate, 86 Litmus, 40, 88 Lixiviation, 94 Lotio nigra, 124 Lubricating oil, 138 Lugol's solution, 39 Lunar caustic, 126 Lustre, metallic, 82 Lyddite, 162 Lye, 91 Magnesia, 103 calcined, 103 milk of, 103 Magnesian fluid, 196 limestone, 102 Magnesium, 102 carbonate, 103 citrate, 103 group, 102 hydrate, 103 Magnesium oxide, 103 phosphate, 103 sulphate, 102 Malt, 229 Maltin, 229 Maltose, 167 Manganates, 112 Manganese, n 1 black oxide of, 21, 38, in chloride, in dioxide, 21, 38,111 Manganous sulphate, 111 sulphide, 112 Marble, 98 Marsh gas, 139 Marsh's test, 68 Massa hydrargyri, 121 Mastic, 141 Matter, 10 states of, 13 Measures, 230 Meerschaum, 102 Menthol, 141 Mercaptans, 148 Mercurial ointment. 121 Mercuric ammonium chloride, 123 chloride, 123 cyanide, 79 iodide, 122 nitrate, 122 oxide, 124. suiphate, 122 sulphide, 124 Mercurous chloride, 123 iodide, 122 nitrate, 122 oxide. 124 sulphate, 122 sulphide, 124 Mercury, 121 acid nitrate, 122 ammoniated, 123 bichloride, 123 biniodide, 122 black oxide, 124 green iodide, 122 mild chloride, 123 oleate, 124 proto-iodide, 122 red iodide, 122 red oxide, 124 yellow iodide, 122 yellow oxide, 124 " Meta," 62 Metalbumin, 173 Metallic lustre, 82 Metals, 18, 81 Methane, 138, 139 Methene, 157 Methenyl, 158 Methyl alcohol, 145 aldehyde, 152 amine, 178 Methylated spirit, 146 Metric measures, 230 Micrococci, 214 Micrococcus urea, 185 Mircro'iganisms, 213 2 3 8 INDEX. Milk, 216 adulteration of, 220 composition of, 217 cow's, 218 of magnesia, 103 of sulphur, 45 pasteurization of, 220 salts, 220 skim, 221 sterilized, 220 sugar, 166. 219 testing, 221 woman's, 218 Millon's reagent, 173 Mineral coal, 73 sperm oil, 138 Mirbane, oil of, 142 Mirrors, 121 Molecular formulae, 136 Molecules, 16 Molybdenum, 117 Monobromated camphor, 141 Monsel's solution, 115 Mordants, 108 Morphine, 179 " Mother of vinegar," 154, 229 Mucilage of starch, 163 Mucin, 201 Mucor mucedo, 229 Mucus, 182, 200 Mulberry calculus, 205 Murexid test, 194 Muscarine, 177 Mushroom, 177 Mustard, 169 Mycoderma aceti, 154, 229 Mydine, 178 Myosin, 174 Myronic acid, 169 Myrosin, 169 Myrrh, 141 Naphtha, 138 Naphthalene, 142 Narceine, 179 Narcotine, 179 Nascent state, 133 Natrium, 89 Natural gas, 139 Negative radicals, 132 Neon, 55 Nessler's reagent, 57, 89 Neuridine, 178 Neurin, 177 Nickel, 117 Nicotine, 179 Nitre, 93 sweet spirits of, 151 Nitrates, 60 Nitration, 60 Nitric oxide, 58 Nitrification, 58 Nitrite of amyl, 151 pentyl, 151 Nitrites, 58 Nitro-aniline, 170 Nitrobenzene, 142 Nitro-cellulose, 163 Nitrogen, 52, 135 dioxide, 58 group, 52 hydride, 55 iodide of, 53 monoxide, 58 oxides, 57 pentoxide, 59 tetroxide, 59 trioxide, 58 Nitro-'glycerine, 159 Nitrous ether, 151 oxide, 58 Nomenclature, 36 Non-metals, 18 Normal salts, 91 Nux vomica alkaloids, 179 Oi'dium aldicans, 229 Oil, fusel, 148 linseed, 155 of mirbane, 142 of peppermint, 141 of vitriol, 50 Oleate of mercury, 124 *' Olefines," 139 Olein, 155 Oleomargarine, 155 Oleo-resins, 141 Oleum terebinthtnae, 140 Oliguria, 182 Oils, essential, 140 fixed, 154 volatile, 140 Onyx, 81 Opium alkaloids, 179 Organic acids, 153 alkalies, 175 chemistry, 133 Organized bodies, 133 Orpiment, 64 " Ortho-," 62 Orthosilicic acid, 81 Osmic acid, 129 Osmium, 129 " ous," 41 Oxacids, 40 Oxalate ot lime, 99, 205 Oxidation, 22 Oxide, definition of, 22 Oxidizing agents, 23 Oxyacetate, 120 Oxychloride of antimony, 70 Oxygen, 21 Oxygenated water, 30 Oxy hydrogen flame, 20 Oxysulphate, 123 Ozone, 23 test for, 24 Ozonized ether, 31 Painter's colic, 85 Palladium, 129 Pancreatin, 229 Paper, 162 Paraffine, 138 Paralbumin, 173 Paraldehyde, 152 I\DEX. 239 Paraxanthine, 178 Parchment, artificial, 163 Parenthesis, 17 Paris green, 66, 120 Pasteurization, 221 Pavy's solution, 202 Pearl ash, 91 white, 71, 105 Pentyl acetate, 148 nitrite, 151 Peppermint, oil of, 141 Pepsin, 225, 229 Peptones, 175, 200, 225 " Per-, ' 36 Permanganates, 112 Peroxide of sodium, 90 Perspiration, 141 Petrolatum, 138 liquidum, 139 molle, 139 spissum, 139 Petroleum, 138 Pewter, 71, 83 Phenates, 159 Phenacetine, 171 Phenol, 159 Phenolphthalein, 97 Phenyl alcohcl, 159 bi-sulphate, 160 Phenylamine, 170 Phloroglucin, 227 Phosphates in urine, 195, 182 Phosphine, 61 Phosphites, 63 Phosphoretted hydrogen, 61 Phosphorus. 60, 136 hydride, 61 oxides and oxacids, 62 pentoxide, 62 red, 60 sun, 22 Phospho-tungstic acid, 200 Photography, 127 Picric acid, 161, 203 test for glucose, 203 Physostigmine, 179 Pig iron, 113 Pilocarpine, 179 Pilula hydrargyri, 121 Pipette, 97 14 ?laster-of-Paris," 99 Plasters, 155 Platinic chloride, 89, 129 Platinum, 129 Plumbago, 73 Plumbum, 82 Polymerism, 137 Polyuria, 181 Porcelain, 109 Porter, 147 Potassium, 90 acid carbonate, 92 bicarbonate, 92 bichromate, in bitartrate, 92 bromide, 93 carbcnate, 91 chlorate, 21 Potassium chromate, in ferricyanide, 80 ferrocyanide, 80 group. 86 hydrate, 94 hypochlorite, 94 iodate, 93 iodide, 93 manganate, 112 nitrate, 93 per nanganate, 112 red chromate, n 1 -sodium tartrate, 94 sulphocyanate, 80, 224 Potato starch, 165 Pottery, 109 Powder of Algaroth, 70 Precedence of affinities, 73 Precipitated chalk, 93 Preliminary group, 19 Propane, 137 Propenyl, 158 Propyl, 144 Propylamine, 169 Proteids, 172, 178 Proto-iodide of mercury, 122 Prussiate of potash, red, 80 yellow, 80 Pseudoxanthine, 178 Ptomaines, 176 Ptyalin, 125, 229 Ptyalism, 125 Purple of Cassius, 129 Pus in urine, 209 test for, 31, 209 Putrefaction, 229 Putrefactive alkaloids, 176 Putrescine, 178 Pyocyanine, 178 " Pyro-", 62 Pyroligneous spirit, 145 Pyrozone, 23 Pyuria, 209 Quartz, 81 Quevenne's iron, 113 Quicklime, 98 Quicksilver, 121 Quimcine, 179 Quinidine, 179 Quinine. 179 Quinoidine, 179 Radicals, definition of, 31 the alcohol, 144 Ramsay, Prof., 55 Rancidity of fats, 155 Rational formulae, 137 Ratsbane, 64 Rayleigh, Lord, 55 Realgar, 64 Red fire, 101 prussiate of potash, 80 Reduced iron, 113 Rennet, 219 Reinsch's test, 123 Resina, 141 Resins, 140 240 INDEX. Resorcin, 160 Respiration, 23 Rhigoline, 138 Rochelle salt, 94 Rock crystal, 81 salt, 90 Roll sulphur, 44 Rosaniline, 170 Rosin (see Resin), 140 Rubber, India, 141 vulcanized, 141 Rubidium, 96 Saccharin, 161 Saccharomyces cerevisiae, 229 Saccharum, 166 Saccharoses, 166 Salamandarine, 178 Salicin, 168 Saliva, 224 Salt-peter, 93 Salts, acid, 91 "bi-," 9x Crab-orchard, 102 Epsom, 102 normal, 91 of tartar, 91 Salivation, 125 Salol, 161 Salophen, 161 Salt, common, Sal-volatile, 88 Samarium, 106 Sand, 81 specific gravity of, 13 Santonin, 169 Saponification, 157 Saponin, 169 Sapphire, 108 Sarcina, 214 Scale compounds of iron, ri6 Scandium, 106 Scheele's green, 66, 120 Secretion of urine, 180 Selenium, 44 Serum-therapy, 179 Sewer gas, 46 Shellac, 141 Siemen's ozone tube, 23 Silica. 81 Silicates, 81 Silicic oxide, 81 Silicon, 81 Silver, 126 action of light on, 127 ammonio-nitrate, 66 arsenite, 66 bromide, 127 chloride, 127 cyanide, 127 German, 117 iodide, 127 nitrate, 126 oxide, 126 Slaked lime, 99 Soaps, 155^ Soap solution, 100 Soapstone, 81, 152 Soda, baking, 90 water, 77 Sodio-potassium tartrate, 94 Sodium, 89 amalgam, 87 bicarbonate, 90 borate, 107 chloride, 89 dioxide, 90 hypobromite, 191 hyposulphite, 49 phosphate, 90 salicylate, 161 sulphate, 90 sulphite, 90 sulphocarbolate, thiosulphate, 49 tungstate, 118 Solder, 83 Soldering, 107 Solid, definition of, 13 Solanin, 169 Solomon, Dr. Leon L., 101 Soluble glass, 81 Solution, Donovan's, 64 Labarraque's, 95 Solution, rationale of, 26 Soot, 74 Spasmotoxine, 177 Specific gravity, 16, 186 flask, 11 weight, 16 Spectroscope, 209 Spermatozoa, 213 Spermine, 178 Spirit, methylated, 146 pyroligneous, 145 wood, 145 Spirits, 87, 147 of hartshorn, 55 of wine, 146 Spiritus setheris nitrosi, 151 ammonise, 87 ammoniae aromaticus, 87 frumenti, 147 vini gallici, 147 Squibb's, 187, 191 Stannic salts, 82 Stannous salts, 82 Stannum, 82 Starch, 164 Steam, 25 Steel, 113 Stereotyping metal, 71 Sterilized milk, 220 Stibine, 69 Stibium, 69 Stomach contents, 226 Strontium, 101 Strychnine, 179 Styptic collodion, 164 Sublimation, 30 Sublimed sulphur, 44 Suboxide of copper, 120 Sugar, beet, 166, 201 cane, 166 corn, 168 diabetic, 167 IXDEX. 2 4 1 Sugar, grape, 167 in urine, 201 milk, 166, 219 of lead, 83 specific gravity of, 13 Sulphates, test for, 51, 197 Sulphites, 49 Sulphocarbolates, 160 Sulpho-cyanates, 80 Sulphonal, 149 Sulph-indigotate of sodium, 18c Sulphur, 44, 45, 135 dioxide, 49 flowers of, 45 group, 44 lotum, 45 milk of, 45 oxides, 48 precipitatum, 45 sublimatum, 45 trioxide, 49 Sulphuretted hydrogen^ 46 Sulphuric ether, 149 Supporter of combustion, 22 Susotoxine, 177 Sweet spirits of nitre, 151 Symbols, 17 Sympathetic ink, 117 Synaptase, 168 Synthesis, 26 Syntonin, 174 Syrupus calcii lactophosphatis, 99 Syrupus scillse compositus, 70 simplex, t66 Table, of alkaloids, 179 of elements, 15 of metric measures, 230 of solubilities, 132 to determine acidulous radicals, 131 to determine metallic radicals, 130 of valences, 35 Tannin, 169 Tanning, 169 Tantalum, 52 Tartar, cream of, 92 emetic, 70 Teeth, filling for, 105 Tellurium, 44 Temperature, influence of, 33 Terebene, 140 Terpenes, 140 Tersulphate of iron, 114 Test-meal, 225 Tests, alcohol, 147 alkali-bismuth, 203 alkoli-copper, 202 ammonia, 57 ammonium salts, 88, 89 antimony, 71 arsenic, 67, 68 barium, 197 bile acids, 207 bile coloring matters, 206 bismuth, 72 biuret, 172 Tests, blood, 209 boron, 107 bromides. 43 bromine, 40 brucine, 179 cadmium, 106 calcium, 100 carbonates, 78 carbon dioxide, 78 carbonic acid, 78 chlorides, 43, 196 chlorine, 40 chloroform, 143 chromates, 84 cobalt, 117 coloring matters, urinary, 194 Congo-red, 226 copper, 119 cyanides, 80 Donne's, 209 fats, 154 Fehling's, 202 fluorides, 43 gallic acid, 162 glucose in urine, 201 Haines', 202 hard water, 100 heat for albumin, 198 hydrocyanic acid, 80 hydrogen sulphide, 47 indigo-carmine, 203 iodides, 43 iodoform, 147 iodine, 40, 165 iron, 116 lead, 85 Lieben's, 205 lithium, 86 manganese, 107 Marsh's, 68, 71 mercury, 125 metallic radicals, 130 morphine, 179 murexid, 194 nickel, 117 nitrates, 60 nitric acid, 60 nitrogenous bodies, 135 organic matter in water, 38 oxalic acid, 157 oxygen, 58 ozone, 24 phenyl-glucosazone, 204 phenyl-hydrazine, 203 phosphates, 63 phosphoric acid, 63 phosphorus, 61 picric acid, 203 platinic chloride, 94 potassium, 36 pus, 31 pyrogallic acid, 163 quinine, 179 Reinsch's, 66 rennet, 227 salicylic acid, 162 silver, 196 242 INDEX. Tests, silver nitrate, 127, 197 sodium, 90 starch, 163 strychnine, 179 strontium, 101 sugar, 167, 201 sulphates, 51, 197 .sulphuric acid, 51 tannic acid, 167 Trommer's, 201 Uffelman's, 227 urates, 182, 191, 194 urea, 188, 190 uric acid, 194 urinary calculi, 215 urinary sediments, 215 water in alcohol, 119 zinc, 105 Tetanine, 176 Tetanotoxine, 177 Theine, 179 Theobromine, 179 Theory, atomic, 15 Tin, 82 Tinct. ferri chloridi, 114 iodi, 39 Tinctures, 87, 147 Tin-foil, 82 Tin-ware, 82 Tolu, 141 Toluene, 142 Torula cerevisise, 229 Toxicology of arsenic, 65 Toxines, 178 Tetrane, 139 Trichloraldehyde, 142 Trichlormethane, 142 Trimethyl amine, 171, 178 Triple-phosphates, 195 Tritane, 139 Tritenyl, 158 nitrate, 159 Tritone, 140 Trityl, 148 Trommer's test, 202 Trypsin, 229 Tube-casts, 211 Tungsten, 117 Turpentine, 140 Turpeth mineral, 123 Type-metal, 83 Typhotoxine, 177 Tyrotoxicon, 177, 220 Tyrosin, 208 Ultimate analysis, 135 Unguentum antimonii, 70 hydrargyri, 121 hydrargyri nitratis, 122 Uranium, 117 Urates, 182, 191 Urea, 80, 170, 179, 181, 188 estimation of, 189 nitrate, 188 quantitative analysis, 190 Uric acid, 192 Urinary calculi, 215 Urinary casts, 211 Urine, 180 abnormal, 198 acid fermentation, 185 acidity, 184 alkaline fermentation, 185 chemical constituents, 188 color, 183 coloring matters, 183, 194 fluidity, 183 mucus, 182 normal, 181 odor, 183 opacity, 182 physical properties, 181 quantity, 181 reaction, 183 specific gravity, 186 transparency, 182 Urinometer, n, 186 Urobilin, 194 Urohaematin, 194 Uroindican, 194 Uroxanthin, 194 Valence, 34 table of, 35 Valerian, 154 Vanadium, 52 Vanillin, 227 Vapor, 25 Vapor-densities, 136 Varnishes, 141 Vaseline, 139 Veratrine, 179 Ventilation, 78 Verdigris, 120 Vermilion, 124 Vibriones, 215 Vinegar, 154 " mother of," 154, 230 Vinum antimonii, 70 Vinum rubrum, 147 Vitellin, 174 Vitriol, blue, 119 green, 114 oil of, 50 white, 104 Volatile oils, 140 Volatility, influence of, 33 Vulcanized rubber, 141 Volumetric solutions, 96 Water, 25 alkaline, 29 analysis, 28 chalybeate, 29 carbonated, 28 distilled, 30 drinkable, 27 filtration, 29 glass, 81 hard, 100 impure, tests for, 28 mineral, 28 natural, 27 lithia, 29 of crystallization, 27 INDEX. 243 Water, oxygenated, 30 potable, 27 purification of, 29 saline, 29 sulphur, 29 thermal, 2,) Waxy casts, 212 Weight, 10 absolute, 10 apparent, 10 atomic, 16 combining, 16 specific, 10 Welding, 107 Wells, 27 Welsbach burner, 109 Werner-Schmidt process, 223 Whey, 219 Whiskey, 147 W T hite arsenic, 64 lead, 84 precipitate, 123 vitriol, 104 " Will-o' the wisp," 61 Wines, 147 Woehler, 133 Woman's milk, 218 Wood alcohol, 145 naphtha, 145 spirit, 145 Woody fibre, 163 Wrought iron, 113 Xanthine, 178, 192 Xanthoproteic, 172 Yeast, 146, 201, 213, 229 Yellow, chrome, 85 iodide of mercury, 122 prussiate of potash, 80 Ytterbium, 106 Yttrium, 106 Zinc, 104 carbonate, 105 chloride, 104 oxide, 105 sulphate, 104 sulphide, 105 white, 105 Zoogleae. 215 NO. 8 APRIL, 1900 A Classified Catalogue of Books on Medicine and the Collateral Sciences, Phar- macy, Dentistry, Chemistry, Hygiene, Microscopy, Etc. e^ P. 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Chemical Analysis of Healthy and Diseased Urine, Qualitative and Quantitative. 39 Illustrations. $1.00 VENEREAL DISEASES. COOPER. Syphilis. 2d Edition, Enlarged and Illustrated with 20 full-page Plates. $5.00 GOWERS. Syphilis and the Nervous System. 1.00 VETERINARY. BALLOU. Veterinary Anatomy and Physiology. 29 Graphic Illustrations. .80; Interleaved, #1.25 TUSON. Veterinary Pharmacopoeia. Including the Outlines of Materia Medica and Therapeutics. 5th Edition. $2.25 WOMEN, DISEASES OF. BYFORD (H. T.). Manual of Gynecology. Second Edition, Revised and Enlarged by 100 pages. With 341 Illustrations, many of which are from original drawings. $3-oo DUHRSSEN. A Manual of Gynecological Practice. 105 Illustrations. $ 1 -S° FULLERTON. Surgical Nursing. 3d Edition, Revised and Enlarged. 69 Illustrations. $1.00 LEWERS. Diseases of Women. 146 Illus. 5th Ed. $2.50 MONTGOMERY. Gynecology. A Text-Book. Abe ut 5c o Illus- trations. 8vo. In Press. WELLS. Compend of Gynecology. Illustrated. 2d Edition. .80; Interleaved, $1. 25 22 SUBJECT CATALOGUE. COMPENDS. From The Southern Clinic. " We know of no series of books issued by any house that so fully meets our approval as these ?Quiz-Compends?. They are well ar- ranged, full, and concise, and are really the best line of text-books that could be found for either student or practitioner." BLAKISTON'S PQUIZ-COMPENDS? The Best Series of Manuals for the Use of Students. Price of each, Cloth, .80. Interleaved, for taking Notes, $1.25. 4&~ These Compends are based on the most popular text-books and the lectures of prominent professors, and are kept constantly re- vised, so that they may thoroughly represent the present state of the subjects upon which they treat. j&tf" The authors have had large experience as Quiz-Masters and attaches of colleges, and are well acquainted with the wants of students. MS" They are arranged in the most approved ,'form, thorough and concise, containing over 6oo fine illustrations, inserted wherever they could be used to advantage. 4S* Can be used by students of way college. &$- They contain information nowhere else collected in such a condensed, practical shape. Illustrated Circular free. No. i. POTTER. HUMAN ANATOMY. Sixth Revised and Enlarged Edition. Including Visceral Anatomy. Can be used with either Morris's or Gray's Anatomy. 117 Illustrations and 16 Lithographic Plates of Nerves and Arteries, with Explanatory Tables, etc. By Samuel O. L. Potter, m.d., Professor of the Practice of Medicine, Cooper Medical College, San Francisco ; late A. A. Surgeon, U. S. Army. No. 2. HUGHES. PRACTICE OF MEDICINE. Part I. Sixth Edition, Enlarged and Improved. By Daniel E. Hughes, m.d., Physician-in-Chief, Philadelphia Hospital, late Demonstrator ot Clinical Medicine, Jefferson Medical College, Phiia. No. 3. HUGHES. PRACTICE OF MEDICINE. Part II. Sixth Edition, Revised and Improved. Same author as No. 2. No. 4. BRUBAKER. PHYSIOLOGY. Ninth Edition, with new Illustrations and a table of Physiological Constants. Enlarged and Revised. By A. P. Brubaker, m.d., Professor of Physiology and General Pathology in the Pennsylvania College of Dental Surgery ; Adjunct Professor of Physiology, Jefferson Medical College, Philadelphia, etc. No. 5. LANDIS. OBSTETRICS. Sixth Edition. By Henry G. Landis, m.d. Revised and Edited by Wm. H. Wells, m.d., Instructor of Obstetrics, Jefferson Medical College, Philadelphia. Enlarged. 47 Illustrations. No. 6. POTTER. MATERIA MEDICA, THERAPEUTICS, AND PRESCRIPTION WRITING. Sixth Revised Edition (U. S. P. 1890). By Samuel O. L. Potter, m.d., Professor of Practice, Cooper Medical College, San Francisco ; late A. A. Sur- geon, U. S. Army. MEDICAL BOOKS. 23 PQUIZ-COMPENDS ?— Continued. No. 7. WELLS. GYNECOLOGY. Second Edition. ByWM.H. Wells, m.d., Instructor of Obstetrics, JeffersoD College, Philadel- phia. 140 Illustrations. No. 8. GOULD AND PYLE. DISEASES OF THE EYE AND REFRACTION. Second Edition. Including Treatment and Surgery, and a Section on Local Therapeutics. By George M. Gould, m.d., and W. L. Pyle, m.d. With Formula, Glossary, Tables, and 109 Illustrations, several of which are Colored. No. 9. HORWITZ. SURGERY, Minor Surgery, and Bandag- ing. Fifth Edition, Enlarged and Improved. By Orville Horwitz, b. s., m.d., Clinical Professor of Genito-Urinary Surgery and Venereal Diseases in Jefferson Medical College ; Surgeon to Philadelphia Hospital, etc. With 98 Formulae and 71 Illustrations. No. 10. LEFFMANN. MEDICAL CHEMISTRY. Fourth Edition. Including Urinalysis, Animal Chemistry, Chemistry of Milk, Blood, Tissues, the Secretions, etc. By Henry Leffmann, m.d., Professor of Chemistry in Pennsylvania College of Dental Surgery and in the Woman's Medical College, Philadelphia. No. 11. STEWART. PHARMACY. Fifth Edition. Based upon Prof. Remington's Text-Book of Pharmacy. By F. E. Stewart, m.d., ph.g., late Quiz-Master in Pharmacy and Chemistry, Phila- delphia College of Pharmacy ; Lecturer at Jefferson Medical College. Carefully revised in accordance with the new U. S. P. No. 12. BALLOU. VETERINARY ANATOMY AND PHY- SIOLOGY. Illustrated. By Wm, R. .Ballou, m.d., Professor of Equine Anatomy at New York College of Veterinary Surgeons ; Physician to Bellevue Dispensary, etc. 29 graphic Illustrations. No. 13. WARREN. DENTAL PATHOLOGY AND DEN- TAL MEDICINE. Third Edition, Illustrated. Containing a Section on Emergencies. By Geo. W. Warren, d.d.s., Chiet ot Clinical Staff, Pennsylvania College of Dental Surgery. No. 14. HATFIELD. DISEASES OF CHILDREN. Second Edition. Colored Plate. By Marcus P. Hatfield, Profes- sor of Diseases of Children, Chicago Medical College. No. 15. HALL. GENERAL PATHOLOGY AND MORBID ANATOMY. 91 Illustrations. By H. Newberry Hall, ph.g., m.d., late Professor of Pathology, Chicago Post-Graduate Medi- cal School. Second Edition. Preparing. No. 16. DISEASES OF THE SKIN. By Jay T. Schamberg, m.d., Professor of Diseases of the Skin, Philadelphia Polyclinic. With 99 handsome Illustrations. Price, each, Cloth, .80. Interleaved, for taking Notes, $1.25. In preparing, revising, and improving Blakiston's ? Quiz-Com- pends ? the particular wants of the student have always been kept in mind. Careful attention has been given to the construction of each sentence, and while the books will be found to contain an immense amount of knowledge in small space, they will likewise be found easy reading ; there is no stilted repetition of words ; the style is clear, lucid, and dis- tinct. The arrangement of subjects is systematic and thorough ; there Is a reason for every word. They contain over 600 illustrations. Morris' Anatomy Second Edition, Revised and Enlarged. 790 Illustrations, of which many are in Colors. Royal Octavo. Cloth, $6.00 ; Sheep, $7.00 ; Half Russia, $8.00. from The Medical Record, New York. " The reproach that the English language can boast of no treatise on anatomy deserving to be ranked with the masterly works of Henle, Luschka, Hyrtl, and others, is fast losing its force. During the past few years several works of great merit have appeared, and among these Morris's " Anatomy " seems destined to take first place in disputing the palm in pnatomical fields with the German classics. The nomencla- ture, arrangement, and entire general character resemble strongly those of the above-mentioned handbooks, while in the beauty and profuseness of its illustrations it surpasses them. . . . The ever-growing popularity of the book with teachers and students is an index of its value, and it may safely be recommended to all interested. ,, *** Handsome Descriptive Circular, with Sample Pages and Colored Illustrations, will be sent free upon' application. 1900