THE MEDICAL STUDENT'S MANUAL OF CHEMISTRY BY R At'WITTHAUS, A.M., M.D. PROFESSOR OF CHEMISTRY AND PHYSICS IN THE UNIVERSITY OF THE CITY OF NEW YORK; PROFESSOR OF CHEMISTRY AND TOXICOLOGY IN THE UNIVERSITY OF BUFFALO ; PROFESSOR (W CHEMISTRY AND TOXICOLOGY IN THE UNIVERSITY OF VERMONT; MEMBER OF THE CHEMI- CAL SOCIETIES OF PARIS AND BERLIN ; MEMBER OF THE AMERI- CAN CHEMICAL SOCIETY ; FELLOW OF THE AMERI- CAN ACADEMY OF MEDICINE, ETC. SECOND EDITION. NEW YORK WILLIAM WOOD & COMPANY 56 & 58 Lafayette Place Copyright, 1887, WILLIAM WOOD & COMPANY. The Publishers' Printing Company 157 and 159 William Street New York PREFACE TO THE PRESENT EDITION. The arrangement and classification adopted in the first edition hare been continued, with the following modifications : That portion treating of chemical physics has been contracted, until it contains nothing not absolutely essential to an understanding of what fol- lows. This has been done in the belief that the sciences of chemistry and 'physics have each assumed a degree of individual importance in their ap- plications to medical science that they should be treated of as distinct sub- jects. The chemistry of the metals has been made to follow that of the non- metals, in spite of the illogical character of such an arrangement, because it is believed that the student should be given as full a drilling in the simpler branches of the subject as possible before he is called upon to face the more complex chemistry of the carbon compounds. The formulae of the acids and salts have been changed from the con- tinental method SO,H,, N03K, etc., adopted in the first edition, to that more generally followed in this country and in England, H2S04, KN03, etc. ; the latter method being more in consonance with our system of nomenclature. That portion of the work treating of the chemistry of the carbon com- pounds has been much extended, and in great part rewritten. The prom- inence given to this portion of the subject the author believes to be justi- fied, notwithstanding its intricacy and the consequent difficulty of teaching it to medical students, by reason of the intimate connection of organic chemistry with physiology and pharmacy, and the rapidly increasing use of complex organic products as medicines. New York, E. A. W. August 21, 1887. PREFACE TO THE FIRST EDITION. In venturing to add another to the already long list of chemical text-books, the author trusts that he may find some apology in this, that the work is intended solely for the use of a class of students whose needs in the study of this science are peculiar. While the main foundations of chemical science, the philosophy of chemistry, must be taught to and studied by all classes of students alike, the subsequent development of the study in its details must be moulded to suit the purposes to which the student will subsequently put his knowledge. And particularly in the case of medical students, in our present defective methods of medical teaching, should the sub- ject be confined as closely as may be to the general truths of chemistry and its applications to medical science. In the preparation of this Manual the author has striven to pro- duce a work which should contain as much as possible of those por- tions of special chemistry which are of direct interest to the medical practitioner, and at the same time to exclude so far as possible, without detriment to a proper understanding of the subject, those portions which are of purely technological interest. The descriptions of pro- cesses of manufacture are therefor made very brief, "while chemical physiology and the chemistry of hygiene, therapeutics, and toxicology have been dwelt upon. The work has been divided into three parts. In the first part the principles of chemical science are treated of, as well as so much of chemical physics as is absolutely requisite to a proper understanding of that which follows. A more extended study of physics is purposely avoided, that subject being, in the opinion of the author, rather within the domain of physiology than of chemistry. The second part treats of special chemistry, and in this certain departures from the methods usually followed in chemical text-books are to be noted. The elements are classed, not in metals and metal- VI PREFACE TO THE FIRST EDITION. loids, a classification as arbitrary as unscientific, but into classes and groups according to their chemical characters. In the text the formula of a substance is used in most instances in place of its name, after it has been described, with a view to giving the student that familiarity with the notation which can only be obtained by continued use. As the distinction between inorganic and organic chemistry is merely one of convenience, the consideration of the carbon compounds is made to follow in its logical place after that of the element carbon. In the third part those operations and manipulations which will be of utility to the student and physician are briefly described ; not with the expectation that these directions can take the place of actual ex- perience in the laboratory, but merely as an outline sketch in aid thereto. Although the Manual puts forth no claim as a work upon analyti- cal chemistry, we have endeavored to bring that branch of the subject rather into the foreground so far as it is applicable to medical chem- istry. The qualitative characters of each element are given under the appropriate heading, and in the third part, systematic schemes for the examination of calculi and of simple chemical compounds are given. Quantitative methods of interest to the physician are also described in their appropriate places. In this connection the author would not be understood as saying that the methods recommended are in all in- stances the best known, but simply7 that they7 are the best adapted to the limited facilities of the physician. The author would have preferred to omit all mention of Troy and Apothecaries’ weight, but in deference to the opinions of those vener- able practitioners who have survived their student days by7 a half cen- tury7, those weights have been introduced in brackets after the metric, as the value of degrees Fahrenheit have been made to follow those Centigrade. Buffalo, N, Y., R. A. W. September 16, 1S83, TABLE OF CONTENTS. PAGE PART I—INTRODUCTION 1 General Properties of Matter '.... 2 Indestructibility 2 Weight 2 Specific gravity 2 States of matter . 6 Divisibility 7 Elements 8 Combination of Elements 8 Atomic Theory 9 Atomic and Molecular Weights . 11 Valence or Atomicity 14 Symbols—Formulae—Equations 15 Electrolysis 16 Acids, Bases, and Salts 18 Nomenclature , 20 Radicals 23 Constitution 23 Classification of Elements 26 Physical Characters 27 Crystallization 27 Isomorphism 30 Dimorphism 31 Allotropy 31 Solution 31 Diffusion 32 Specific heat 33 Spectroscopy 33 Polarimetry 36 CONTENTS. PAGE PART II—SPECIAL CHEMISTRY 37 Typical Elements 37 Hydrogen 37 Oxygen 40 Ozone 42 Water 43 Hydrogen dioxide 52 Acidulous Elements 54 Chlorine Group 54 Fluorine .....’ 54 Hydrogen fluoride 54 Chlorine 55 Hydrogen chloride 57 Compounds of chlorine and oxygen 58 Bromine.... 59 Hydrogen bromide 59 Oxacids of bromine 60 Iodine 60 Hydrogen iodide 61 Oxacids of iodine ... 62 Sulphur Group 62 Sulphur 63 Hydrogen sulphide 64 . Sulphur dioxide 66 Sulphur trioxide 67 Hydrosulphurous acid 67 Sulphuric acid 67 Pyrosulphuric acid 69 Selenium 69 Tellurium 70 Nitrogen Group 70 Nitrogen .. 70 Atmospheric air 71 Ammonia 72 Nitrogen monoxide 73 Nitrogen dioxide 74 Nitrogen trioxide 74 Nitrogen tetroxide 74 Nitrogen pentoxide 75 Nitrogen acids 75 Nitric acid 76 Compounds of nitrogen with the halogens 77 Phosphorus 78 Hydrogen phosphides 82 Oxides of phosphorus 82 Phosphorus acids 83 Compounds of phosphorus with the halogens 84 Arsenic 84 Hydrogen arsenides 85 Oxides of arsenic 86 CONTENTS. IX PAGH Arsenic acids 88 Sulphides of arsenic 88 Haloid compounds of arsenic,... 89 Arsenical poisoning 89 Analytical 92 Antimony 97 Hydrogen antimonide 97 Oxides of antimony 97 Antimony acids 98 Chlorides of antimony 98 Sulphides of antimony 99 Antimonial poisoning 100 Analytical 100 Boron Group 100 Boron 100 Boron oxide and acids .... 101 Carbon Group 101 Carbon 101 Silicon 103 Vanadium Group 104 Molybdenum Group 104 Amphoteric Elements 105 Gold Group 105 Iron Group 105 Chromium 106 Manganese 101 Iron 108 Compounds of iron 109 Salts of iron HI Aluminium Group 114 Glucinium 114 Aluminium 114 Scandium HI Gallium HI Indium HI Uranium Group 118 Lead Group 118 Bismuth Group 122 Tin Group 124 Platinum Group 126 Basylous Elements 129 Sodium Group 129 Lithium 129 Sodium 130 Potassium 185 Silver 142 Ammonium 144 Thallium Group 146 Calcium Group 147 Calcium 147 X PAGE Strontium 151 Barium 151 Magnesium Group 152 Magnesium 153 Zinc . 155 Cadmium 157 Nickel Group . 157 Copper Group 158 Copper... 158 Mercury 162 Compounds of Carbon 168 Homologous series 169 Isomerism 170 Classification of organic substances 171 First Series of Hydrocarbons 172 Haloid derivatives 1<4 Monoatomic alcohols . 177 Simple e hers 188 Monobasic acids 191 Compound ethers 197 Aldehydes 200 Ketones or acetones 203 Monamines 205 Monamides 208 Amido acids... 209 Compounds with other elements 219 Allylic series 221 Acrylic acids and aldehydes 224 Polyatomic compounds 226 Second Series of Hydrocarbons 228 Diatomic alcohols 229 Diatomic, monobasic acids . 232 Diatomic, dibasic acids 246 Compound ethers 248 Aldehydes and anhydrides 249 Amines 249 Amides 250 Compound ureas 2.19 Triatomic alcohols 263 Acids 265 Ethers ... 265 Fats and oils 267 Third Series of Hydrocarbons 275 Tetratomic alcohols 276 Acids 276 Fourth Series of Hydrocarbons 278 Carbohydrates 282 Glucoses 282 Saccharoses 289 Amyloses ,, 291 CONTENTS. CONTENTS PAGE Aromatic mbstances 296 Fijth Series of Hydrocarbons 297 Haloid derivatives 600 Phenols 302 Alcohols 309 Alphenols 310 Aldehydes 310 Acids 311 Araido derivatives 313 Azo and diazo derivatives 316 Hydrazines 317 Pyridine bases 317 Chinoline bases 318 Indigo Group ... 319 Sixth Series of Hydrocarbons 321 Alcohols 321 Seventh Series of Hydrocarbons 322 Eighth Series of Hydrocarbons 322 Derivatives 323 Ninth Series of Hydrocarbons 324 Tenth Series of Hydrocarbons 324 Eleventh Series of Hydrocarbons 324 Derivatives 325 Higher Series of Hydrocarbons 325 Cyanogen Compounds 326 Glucosides 328 Alkaloids 331 Albuminoids and gelatinoids 345 Animal cryptolytes 353 Animal coloring matters 354 PART HI—CHEMICAL TECHNICS 357 General Rules 357 Reagents 358 Glass tubing • • • 358 Collection of gases 359 Solution 360 Precipitation, decantation, etc 361 Evaporation, drying, etc 363 Weighing 365 Measuring 366 Scheme for Analysis of Calculi 368 Scheme for Analysis of Mineral Compounds 369 Table of Solubilities 374 Table of Weights and Measures 375 INDEX 377 THE MEDICAL STUDENT’S MANUAL OF CHEMISTRY PART I. INTRODUCTION. The simplest definition of chemistry is a modification of that given by Webster: That branch of science which treats of the composition of sub- stances, their changes in composition, and the laws governing such changes. If a bar of soft iron be heated sufficiently it becomes luminous; if caused to vibrate it emits sound ; if introduced within a coil of wire through which a galvanic current is passing, it becomes magnetic and at- tracts other iron brought near it. Under all these circumstances the iron is still iron, and so soon as the heat, vibration, or galvanic current ceases, it will be found with its original characters unchanged ; it has suffered no change in composition. If now the iron be heated in an atmosphere of oxygen gas it burns and is converted into a substance which, although it contains iron, has neither the appearance nor the properties of that metal. The iron and a part of the oxygen have disappeared and have been con- verted into a new substance, differing from either ; there has been change in composition, there has been chemical action. Changes wrought in matter by physical forces, such as light, heat and electricity are temporary, and last only so long as the force is in activity; except in the case of changes in the state of aggregation, as when a substance is pulverized or fashioned into given shape. Changes in chemical composition are permanent, last- ing until some other change is brought about by another manifestation of chemical action. However distinct chemical may thus be from physical forces, it is none the less united with them in that grand correlation whose existence was first announced by Grove, in 1842. As, from chemical action, manifesta- tions of every variety of physical force may be obtained : light, heat, and mechanical force from the oxidation of carbon ; and electrical force from the action of zinc upon sulphuric acid—so does chemical action have its origin, in many instances, in the physical forces. Luminous rays bring about the chemical decomposition of the salts of silver, and the chemical union of chlorine and hydrogen ; by electrical action a decomposition of many compounds into their constituents is instituted, while instances are 2 MANUAL OF CHEMISTRY. abundant of reactions, combinations, and decompositions which require a certain elevation of temperature for their production. While, therefor, chemistry in the strictest sense of the term, deals only with those actions which are attended by a change of composition in the material acted upon, yet chemical actions are so frequently, nay universally, affected by existing physical conditions, that the chemist is obliged to give his attention to the science of physics, in so far, at least, as it lias a bearing upon chemical reactions, to chemical physics—a branch of the subject which has afforded very important evidence in support of theoretical views originating from purely chemical reactions. General Properties of Matter. Indestructibility.—The result of chemical action is change in the composition of the substance acted upon, a change accompanied by cor- responding alterations in its properties. Although we may cause matter to assume a variety of different forms and render it, for the time being, invisible, yet in none of these changes is there the smallest particle of matter destroyed. When carbon is burned in an atmosphere of oxygen, it disappears, and, so far as we can learn by the senses of sight or touch, is lost; but the result of the burning is an invisible gas, whose weight is equal to that of the carbon which has disappeared, plus the weight of the oxygen required to burn it. Weight. —All bodies attract each other with a force which is in direct proportion to the amount of matter which they contain. The force of this attraction exerted upon surrounding bodies by the earth becomes sensible as weight, when the motion of the attracted body toward the centre of gravity of the earth is prevented. In chemical operations we have to deal with three kinds of weight: absolute, apparent, and specific. The Absolute Weight of a body is its weight in vacuo. It is deter- mined by placing the entire weighing apparatus under the receiver of an air-pump. The Apparent Weight, or Relative Weight, of a body is that which we usually determine with our balances, and is, if the volume of the body weighed be greater than that of the counterpoising weights, less than its true weight. Every substance in a liquid or gaseous medium suffers a loss of apparent weight equal to that of the volume of the medium so dis- placed. For this reason the apparent weight of some substances may be a minus quantity ; thus, if the air contained in a vessel suspended from one arm of a poised balance be replaced by hydrogen, that arm of the balance to which the vessel is attached will rise, indicating a diminution in weight. (See Weighing ; Part III.) The Specific Weight or Specific Gravity of a substance is the weight of a given volume of that substance, as compared with the weight of an equal bulk of some substance, accepted as a standard of comparison, under like conditions of temperature and pressure. The sp. gr. of solids and liquids are referred to water ; those of gases to air or to hydrogen. Thus the sp. gr. of sulphuric acid being 1.8, it is, volume for volume, one and eight-tenths times as heavy as water. As, by reason of their different rates of expansion by heat, solids and liquids do not have the same sp. gr. at all temperatures, that at which the observation is made should always be noted, or some standard temperature adopted. The standard tempera- GENERAL PROPERTIES OF MATTER. 3 ture adopted by some continental writers and in tlie U. S. P. is 15° (59° F.); other standard temperatures are 4 (39.2C F.), the point of greatest density of water, used by most continental writers, and 15.6° (60° F.), used in Great Britain and to some extent in this country. The determination of the specific weight of a substance is frequently of great service. Sometimes it affords a rapid means of distinguishing between two substances similar in appearance ; sometimes in determining the quantity of an ingredient in a mixture of two liquids, as alcohol and water ; and frequently in determining approximately the quantity of solid matter in solution in a liquid. It is the last object which Ave have in view in determining the sp. gr. of the urine. An aqueous solution of a solid has a higher sp. gr. than pure water, the increase in sp. gr. folloAving a regular but different rate of increase with each solid. In a simple solution—one of common salt in water, for instance—the proportion of solid in solution can be de- termined from the sp. gr. In complex solutions, such as the urine, the sp. gr. does not indicate the propor- tion of solid in solution with accuracy. In the absence of sugar and albumen, a determination of the sp. gr. of urine affords an indication of the amount of solids sufficiently accurate for usual clinical purposes. More- over, as urea is much in excess over other urinary sol- ids, the oscillations in the sp. gr. of the urine, if the quantity passed in tAventy-four hours be considered, and in the absence of albumen and sugar, indicate the variations in the elimination of urea, and consequently the activity of disassimilation of nitrogenous material. To determine the sp. gr. of substances, different methods are adopted, according as the substance is in the solid, liquid, or gaseous state ; is in mass or in powder; or is soluble or insoluble in water. Solids.—The substance is heavier than water, insoluble in that liquid, and not in powder.—It is attached by a fine silk fibre or platinum wire to a hook arranged on one arm of the balance, and Aveiglied. A beaker full of })ure Avater is then so jffaced that the body is immersed in it (Fig. 1.), and a second Aveigliing made. By dividing the weight in air by the loss in water, the sp. gr. (Avater =1.00) is obtained. Example : Fig. 1. A piece of lead weighs in air 82.0 A piece of lead weighs in water 74.0 Loss in water 7.1 82.0 7.1 — 11.55 — sp. gr. of lead. The substance is in poivder, insoluble in water.—The specific gravity bottle (Fig. 2) filled with water, and the powder previously weighed and in a separate vessel, are weighed together. The water is poured out of the bottle, into which the powder is introduced with enough water to fill the bottle completely : the weight of the bottle and its contents is now determined. The weight of the powder alone, divided by the loss between the first and second weighings, is the specific gravity. Example : Weight of iron filings used 6.562 Weight of iron filings and sp. gr. bottle filled with water 148.327 Weight of sp. gr. bottle containing iron filings and filled with water 147.470 Water displaced by iron 0.857 6.562 0.857 = 7.65 = sp. gr. of iron. 4 MANUAL OF CHEMISTRY. The substance is lighter than water.—A sufficient bulk of some heavy substance, whose sp. gr. is known, is attached to it and the same method followed, the loss of weight of the heavy substance being subtracted from the total loss. Example : A fragment of wood weighs 4.3916 A fragment of lead weighs iu.6193 Wood with lead attached weighs 15.0139 Wood with lead attached weighs in water 5.9295 Loss of weight of combination 9.0844 Loss of weight of lead in water • 0.7903 Loss of weight of wood 8.2941 4.3946 8.2941 = 0.529 = sp. gr. of wood. The substance is soluble in or decomposable by water.—Its specific gravity, referred to some liquid not capable of acting on it, is determined, using that liquid as water is used in the case of insoluble substances. The sp. gr. so obtained, multiplied by that of the liquid used, is the sj). gr. sought. Example : A piece of potassinm weighs 2.576 A sp. gr. bottle full of naphtha, sp. gr. 0.758, weighs. 22.784 25.360 The bottle with potassium and naphtha weighs 23.103 Loss 2.257 2.576 2.257 ~ 1.141 x 0.758 = 0.865 = sp. gr. of potassium. Liquids.—The sp. gr. of liquids is determined by the specific gravity bottle, sometimes called picnometer, or by the spindle or hydrometer. By the bottle.—This method is the more accurate, and, if a balance be at hand, is easily conducted. A bottle of thin glass (Fig. 2) is so made as to contain a given volume of water, say 100 c.c., at 15° C., and its weight is determined once for all. To use the picnometer, it is filled with the liquid to be examined and weighed. The weight obtained, minus that of the bottle, is the sp. gr. sought if the bottle contain 1000 c.c. ; -jU if 100 c.c., etc. Example : Having a bottle whose weight is 35.35, and which contains 100 c.c. ; filled with urine it weighs 137.91, the sp. gr. of the urine is 137.91-35.35=102.56x10 = 1025.0 Water=1000. ' By the spindle.—Tlie method by the hydrometer is based upon the fact that a solid will sink in a liquid whose sp. gr. is greater than its own, until it has displaced a volume of the liquid whose weight is equal to its own ; and all forms of hydrometers are simply contrivances to measure the volume of liquid which they displace when immersed. The hydrome- ter most used by physicians is the urinometer (Fig. 3); it should not be chosen too small, as the larger the bulb, and the thinner and longer the stem, the more accurate are its indications. The most convenient method of using the instrument is as follows : The cylinder, which should have a foot and rim, but no pouring lip, is filled to within an inch of the top ; the spindle is then floated and the cylinder completely filled with the liquid under examination (Fig. 3). The reading is then taken at the highest point a, where the surface of the liquid comes in contact with the spindle.* * The advantages of the method described over that usually followed are : Greater facility in reading, less liability to error, the possibility of taking the reading in opaque liquids, and the fact that readings are made upward, not downward. The spindles require to be specially graduated, and are made by Baudin, of Paris, and Eimer & Amend, of New York. GENERAL PROPERTIES OF MATTER. In all determinations of sp. gr. the liquid examined should have the temperature for which the instrument is graduated, as all liquids expand with heat and contract when cooled, and consequently the result obtained will be too low if the urine or other liquid be at a temperature above that at which the instrument is intended to be used, and too high if below that temperature. An accurate correction may be made for temperature in Fig. 3. simple solutions ; in a complex fluid like the urine, however, this can only be done roughly by allowing 1° of sp. gr. for each 33 C. (5.4° Fahr.) of variation in temperature. Gases and Vapors.—The specific gravities of gases and vapors are of great importance in theoretical chemistry, as from them we can determine molecular weights, in obedience to the law of Avogadro (p. 14). Fig. 2. Gases.—The specific gravities of gases are obtained as follows : A glass flask of about 300 c.c. capacity, having a neck 20 centimetres long and 6 millimetres in diameter, and fitted with a glass stopcock, is filled with mercury; reversed over mercury ; and filled with the gas to just, below the stopcock. The stopcock is now closed ; the temperature, t; the barometric pressure, H ; and the height of the mercurial column in the neck above that in the trough, A, are determined, and the flask weighed. Let P be the weight found, and V the capacity of the flask, determined once for all, then - - 760 (1+0.00366 t) = V0 = the volume of the gas at 0° and 760 mm. The flask is then brought under the receiver of an air-pump, the glass stopcock being open, and the air alternately exhausted and allowed to enter until the gas in the flask is replaced by air. The temperature t', the barometric pressure H', and the weight of the flask filled with air P'. are now determined. From thes* results the weight, K. of the gas occupying the volume V0 is obtained by the formula : K-P r'+760 (1 + 0.00366 t')X a001293 The sp. gr. referred to air is found by the formula : K V0 x 0.001293 and that referred to hydrogen by the formula : K V„ x 0.001293 x 0.00927 6 MANUAL OF CHEMISTRY. Vapors.—The specific gravity of vapors is best determined by Meyer’s method, as follows: A small, light glass vessel (Fig. 4) is filled completely with the solid or liquid whose vapor density is to be determined, and weighed ; from this weight that of the vessel is subtracted ; the difference being the weight of the substance P. The small vessel and contents are now introduced into the large branch of the apparatus (Fig. 5), whose weight is then determined. The apparatus is now filled with mer- cury, the capillary opening at the top of the larger branch is closed by the blow-pipe, and the whole again weighed. The apparatus is suspended by a metallic wire near the bottom of a long tube closed at the bottom, and containing about 5U c.c. of some liquid whose boiling-point is con- stant and higher than that of the substance experimented on. When the liquid has been heated to active boiling, and the mercury ceases to escape from the small tube, the barometric pressure and the temperature of the air are observed. After the apparatus is cooled, the tube (Fig. 5), with its contents, is weighed, and the difference in the level of mercury which existed in the two branches during the heating determined by breaking the capillary point, tilting the apparatus un- til the smaller branch is completely filled, marking the level of mercury in the larger branch, and afterward measuring the distance from that point to the opening. By the above process the following factors are determined: Fig. 4. P = weight of substance ; T = boiling-point of external liquid ; t — temperature of air; H = barometric pressure reduced to 0° ; h — difference in level of mercury in two branches of tube; li' — tension of vapor of mercury at T ; a = weight of mercury used ; q — weight of mercury required to fill the tube Fig. 4 ; r = weight of mercury remaining in the apparatus after heating. From these the specific gravity, air = 1, is obtained by the equation : P 760 (1 + 0.00367 T) 13.B9 ' — {VL+h + h') 0.0012933 [{a+q)\ 1 + 0.0000303 (T—*) }•-!•■{ 1+0.0C018 (T-t) }-] [1 +0.00018 t] The sp. gr. in terms of air = 1 may be reduced to sp. gr. referred to hydrogen = 2, by dividing by 0.06927. States of Matter.—Matter exists in one of three states ; solid, liquid, and gaseous. In the solid form the particles of matter are comparatively close together, and are separated with more difficulty than are those of liquid or gaseous matter ; or, in other words, the cohesion of solid matter is greater than that of the other two forms. In the liquid the particles are less firmly bound together and are capable of freer motion about one another. In the gas the mutual attraction of the particles disappears entirely, and their distance from each other depends upon the pressure to which the gas is subjected. The term fluid applies to both liquids and gases, the former being designated as incompressible, from the very slight degree to which their volume can be reduced by pressure. The gases are designated as compressible fluids, from the fact that their volume can be reduced by pressure to an extent limited only by their passage into the liquid form. It is highly probable that all substances, which are not decomposed when heated, are capable of existing in the three forms of solid, liquid, and gas. There are, however, some substances which are only known in two forms—as alcohol; or in a single form—as carbon ; probably because we are as yet unable to produce artificially a temperature sufficiently low to solidify the one, or sufficiently high to liquefy or volatilize the other. Since the liquefaction of the so-called permanent gases the distinction between gases and vapors is only one of degree and of convenience. The passage of a substance from one form to another is always attended by the absorption or liberation of a defi- nite amount of heat. In passing from the solid to the gas- eous form, a body absorbs a definite amount of heat with each change of form. If a given quantity of ice at a temperature below the freezing-point of water be heated, its temperature gradually rises until the thermometer marks 0° C., at which point it remains stationary until Pig. 5. GENERAL PROPERTIES OF MATTER. 7 the last particle of ice has disappeared. At that time another rise o' the thermometer begins, and continues until 100° C. is reached (at 760 mm. of barometric pressure), when the water boils, and the thermometer re- mains stationary until the last particle of water has been converted into steam ; after which, if the application of heat be continued, the thermom- eter again rises. During these two periods of stationary thermometer, heat is taken up by the substance, but is not indicated by the thermom- eter or by the sense. Not being sensible, it is said to be latent, a term which is liable to mislead, as conveying the idea that heat is stored up in the substance as heat ; such is not the case. During the period of station- ary thermometer the heat is not sensible as heat, for the reason that it is being used up in the work required to effect that separation of the par- ticles of matter which constitutes its passage from solid to liquid or from liquid to gas. The amount of heat required to bring about the passage of a given weight of a given substance from the denser to the rarer form is always the same, and the temperature indicated by the thermometer during this passage is always the same for that substance, unless in either case a modi- fication be caused by a variation in pressure. The degree of temperature indicated by the thermometer while a substance is passing from the solid to the liquid state is called its f using-point / that indicated during its pas- sage from the liquid to the gaseous form, its boiling-point. The absorption of heat by a volatilizing liquid is utilized in the arts and in medicine for the production of cold (which is simply the absence of heat), in the manufacture of artificial ice, and in the production of local anaes- thesia by the ether-spray. The removal of heat from the body in this way, by the evaporation of perspiration from the surface, is an important factor in the maintenance of the body temperature at a point consistent with life. When a substance passes from a rarer to a denser form it gives out— liberates—an amount of heat equal to that which it absorbed in its passage in the opposite direction. It is for this reason that, while we apply heat to convert a liquid into a vapor, we apply cold to reduce a gas to a liquid. As a rule, the tliermometrical indication is the same in whichever direction the change of form occurs ; some substances, however, solidify at a tem- perature slightly different from that at which they fuse. Most solids, when heated, are first converted into liquids, and these into gases ; there are, however, some exceptions to this rule. Most vapors when condensed pass into the liquid form, and this in turn into the solid ; some substances, however, are condensed from the form of vapor directly to that of solid, in which case they are said to sublime. Divisibility.—All substances are capable of being separated, with greater or less facility, by mechanical means into minute particles. With suitable apparatus, gold may be divided into fragments, visible by the aid of the microscope, whose weight would be -jinro oo1o7nro7n)' a grain ; and it is probable that when a solid is dissolved in a liquid a still greater sub- division is attained. Although we have no direct experimental evidence of the existence of a limit to this divisibility, we are warranted in believing that matter is not infinitely divisible. A strong'argument in favor of this view being that, after physical subdivision has reached the limit of its power with regard to compound substances, these may be further divided into dissimilar bodies by chemical means. The limit of mechanical subdivision is the molecule of the physicist, the smallest quantity of matter with which he has to deal. 8 MANUAL OF CHEMISTRY. Elements. If we examine the various substances existing upon and in our earth, we find that many of them can be so decomposed as to yield two or more other substances, distinct in their properties from the substance from whose decomposition they resulted, and from each other. If, for example, sugar be treated with sulphuric acid it blackens, and a mass of charcoal separates. Upon further examination we find that water has also been produced. From this water we may obtain two gases, differing from each other widely in their properties. Sugar is therefor made up of carbon and the two gases, hydrogen and oxygen ; but it has the properties of sugar, and not those of either of its constituent parts. There is no method known by which carbon, hydrogen, and oxygen can be split up, as sugar is, into other dissimilar substances. An element or simple substance is a substance which cannot by any known means be split up into other dissimilar bodies. The number of well-characterized elements at present known is sixty- six. During a few years past the discovery of other elements not included in the above number, decipium, philippium, davyium, norwegium, and nep- tunium, has been announced. Laws Governing the Combination of Elements. The alchemists, Arabian and European, contented themselves in accu- mulating a store of knowledge of isolated phenomena, without, as far as we know, attemping, in any serious way, to group them in such a manner as to learn the laws governing their occurrence. It was not until the latter part of the last century, 1777, that Wenzel, of Dresden, implied, if he did not distinctly enunciate, what is known as the law of reciprocal pro- portions. A few years later, Richter, of Berlin, confirming the work of Wenzel, added to it the law of definite proportions, usually called Dalton’s first law. Finally, as the result of his investigations from 1804 to 1808, Dalton added the law of multiple proportions, and, reviewing the work of his predecessors, enunciated the results clearly and distinctly. Considering these laws, not in the order of their discovery, but in that of their natural sequence, we have : The Law of Definite Proportions.— The relative weights of elementary substances in a compound are definite and invariable. If, for example, we anatyze water, we find that it is composed of eight parts by weight of oxy- gen for each part by weight of hydrogen, and that this proportion exists in every instance, whatever the source of the water. If, instead of decom- posing, or analyzing water, we start from its elements, and by synthesis, cause them to unite to form water, we find that, if the mixture be made in the proportion of eight oxygen to one hydrogen by weight, the entire quantity of each gas will be consumed in the formation of water. But if an excess of either have been added to the mixture, that excess will re- main after the combination. Compounds are substances made up of two or more elements united with each other in definite proportiofis. Compounds exhibit properties of their own, which differ from those of the constituent elements to such a degree that the properties of a compound can never be deduced from a knowledge of those of the constituent elements. Common salt, for instance, is com- THE ATOMIC THEORY. posed of 39.32 per cent, of the light, bluish-white metal, sodium, and 60.68 per cent of the greenish-yellow, suffocating gas, chlorine. A mixture is composed of two or more substances, elements or compounds, mingled in any proportion. The characters of a mixture may be predicated from a knowledge of the properties of its constituents. Thus sugar and water may be mixed in any proportion and the mixture will have the sweetness of the sugar, and will be liquid or solid according as the liquid or solid ingredient predominates in quantity. The Law of Multiple Proportions.— When two elements unite with each other to fonn more than one compound, the resulting compounds contain simple multiple proportions of one element as compared with a constant quan- tity of the other. Oxygen and nitrogen, for example, unite with each other to form no less than five compounds. Upon analysis we find that in these the two elements bear to each other the following relations by weight: In the first, 14 parts of nitrogen to 8 of oxygen. In the second, 14 parts of nitrogen to 8 x 2 = 16 of oxygen. In the third, 14 parts of nitrogen to 8 x 3=24 of oxygen. In the fourth, 14 parts of nitrogen to 8 x 4=32 of oxygen. In the fifth, 14 parts of nitrogen to 8 x 5 = 40 of oxygen. The Law of Reciprocal Proportions.— The ponderable quantities in ivhich substances unite with the same substance express the relation, or a simple mul- tiple thereof, in which they unite until each other. Or, as Wenzel stated it, “the weights b, b', b" of several bases which neutralize the same w’eight a of an acid are the same which will neutralize a constant weight a of another acid ; and the weights a, a', a" of different acids which neutralize the same xveiglit b of a base are the same which will neutralize a constant weight of another base 6'.” The Atomic Theory. The laws of Wenzel, Richter, and Dalton, given above, are simply gen- eralized statements of certain groups of facts, and, as such, not only admit of no doubt, but are the foundations upon which chemistry as an exact science is based. Dalton, seeking an explanation of the reason of being of these facts, was led to adopt the view, held by the Greek philosopher Democritus, that matter was not infinitely divisible. He retained the name atom (arofxoi = indivisible), given by Democritus to the ultimate particles of which matter was supposed by him to be composed ; but rendered the idea more precise by ascribing to these atoms real magnitude and a definite weight, and by considering elementary substances as made up of atoms of the same kind, and compounds as consisting of atoms of different kinds. This hypothesis, the first step toward the atomic theory as entertained to-day, afforded a clear explanation of the numerical results stated in the three laws. If hydrogen and oxygen always unite together in the propor- tion of one of the former to eight of the latter, it is because, said Dalton, the compound consists of an atom of hydrogen, weighing 1, and an atom of oxygen, weighing 8. If, again, in the compounds of nitrogen and oxy- gen, we have the two elements uniting in the proportions 14 : 8 14 : 8 x 2 14 : 8 x 3 14 : 8 x 4 14 : 8 x 5, it is because they are 10 MANUAL OF CHEMISTRY. severally composed of an atom of nitrogen weighing 14, united to 1, 2, 3, 4, or 5 atoms of oxygen, each weighing 8. Further, that compounds do not exist in which any fraction of 8 oxygen enters, because 8 is the weight of the indivisible atom of oxygen. One of the chief advantages of Dalton’s hypothesis is in the introduc- tion of this precise and simple relation between the quantities of the con- stituents of a compound. Chemists before Dalton’s day, in expressing the results of their analyses, did not progress beyond statements of the percentage composition. Expressing the composition of four of the carbon compounds in percentages, we have : Marsh gas Carbon. 75.0 Hydrogen. 25.0 Oxygen. = 100 Olefiant gas 85.7 14.3 • • • • = 100 Carbonic oxide .... .... . 42.9 57.1 = 100 Carbonic acid 27.3 72.7 = 100 These figures convey nothing beyond the mere centesimal composition of the substances which they express. The cardinal point of Dalton’s dis- covery lies in his translation of them into the simple relations: Carbon. Hydrogen. Oxygen. Marsh gas 6 2 Olefiant gas G 1 Carbonic oxide 6 8 Carbonic acid 6 16 Dalton’s hypothesis of the existence of atoms as definite quantities did not, however, meet with general acceptance. Davy, Wollaston, and others considered the quantities in which Dalton had found the elements to unite with each other, as mere proportional number's or equivalents, as they ex- pressed it, nor is it probable that Dalton’s views would have received any further recognition until such time as they might have been exhumed from some musty tome, had their publication not been closely followed by that of the results of the labors of Humboldt and of Gay Lussac, concern- ing the volumes in which gases unite with each other. In the form of what are known as Gay Lussac’s laws, these results are : First.—There exists a simple relation between the volumes of gases which combine with each other. Second.—There exists a simple relation between the sum of the volumes of the constituent gases, and the volume of the gas formed by their union. For example : 1 volume chlorine unites with 1 volume hydrogen to form 2 volumes hydrochloric acid. 1 volume oxygen unites with 2 volumes hydrogen to form 2 volumes vapor of water. 1 volume nitrogen unites with 3 volumes hydrogen to form 2 volumes ammonia. 1 volume oxygen unites with 1 volume nitrogen to form 2 volumes nitric oxide. 1 volume oxygen unites with 2 volumes nitrogen to form 2 volumes nitrous oxide. Berzelius, basing liis views upon these results of Gay Lussac, modified the hypothesis of Dalton and established a distinction between the equiva- lents and atoms. The composition of water he expressed, in the notation which he was then introducing, as being H.,0, and not HO a/5 Dalton's hypothesis called for. As, however, Berzelius still considered the atom of oxygen as weighing 8, he was obliged also to consider the atoms of hydrogen and of certain other elements as double atoms—a fatal defect in his system, which led to its overthrow and the re-establishment of the formula HO for water. ATOMIC AND MOLECULAR WEIGHTS. 11 It was reserved to Gerhardt to clearly establish the distinction be- tween atom and molecule ; to observe the bearing of the discoveries of Avogadro and Ampere upon chemical philosophy ; and thus to establish the atomic theory as entertained at present. As a result of his investigations in the domain of organic chemistry, Gerhardt found that, if Dalton’s equivalents be adhered to, whenever car- bonic acid or water is liberated by the decomposition of an organic- sub- stance, it is invariably in double equivalents, never in single ones ; always 2C02 or 2HO or some multiple thereof, never C02 or HO. He further found that if the equivalents C=6, H=l, and 0=8 be retained, the for- mulae became such that the equivalents of carbon are always divisible by two. In fact, he found the same objections to apply to the notation then in use that had been urged against that of Berzelius. In 1811, Avogadro, from purely physical researches, had been enabled to state the law which is now known by his name, to the effect that equal volumes of all gases, under like conditions of temperature and pressure, con- tain equal numbers of molecules. In the hands of Gerhardt this law, in connection with those of Gay Lussac, became the foundation of what is sometimes called the “ new chemistry.” Bearing in mind Avogadro’s law, we may translate the first three combinations given in the table on p. 10 into the following: 1 molecule chlorine unites with 1 molecule hydrogen to form 2 molecules hydrochloric acid. 1 molecule oxygen unites with 2 molecules hydrogen to form 2 molecules vapor of water. 1 molecule nitrogen unites with 3 molecules hydrogen to form 2 molecules ammonia. But the ponderable quantities in which these combinations take jfface are : 35.5 chlorine to 1 hydrogen. 16 oxygen to 2 hydrogen. 14 nitrogen to 3 hydrogen. And as single molecules of hydrogen, oxygen, and nitrogen are in these combinations subdivided to form 2 molecules of hydrochloric acid, water, and ammonia, it follows that these molecules must each contain two equal quantities of hydrogen, oxygen, and nitrogen, less in size than the mole- cules themselves. And, further, as in these instances each molecule con- tains two of these smaller quantities, or atoms, the relation between the weights of the molecules must be also the relation between the weights of the atoms, and we may therefor express the combinations thus : , 1 atom chlorine weighing 35.5 unites with 1 atom hydrogen weighing 1 ; 1 atom oxygen weighing 16 unites with 2 atoms hydrogen weighing 2 ; 1 atom nitrogen weighing 14 unites with 3 atoms hydrogen weighing 3 ; and consequently, if the atom of hydrogen weighs 1, that of chlorine weighs 35.5, that of oxygen 16, and that of nitrogen 14. Atomic and Molecular Weights. Atomic Weight.—The distinction between molecules and atoms may be expressed by the following definitions : A molecule is the smallest quantity of any substance that can exist in the free state. 12 MANUAL OF CHEMISTRY, An atom is the smallest quantity of an elementary substance that can enter vito a chemical reaction. The molecule is always made up of atoms, upon whose nature, num- ber, and arrangement with regard to each other, the properties of the sub- stance depend. In an elementary substance the atoms composing the molecules are the same in kind, and usually two in number. In com- pound substances they are dissimilar and vary in quantity from two in a simple compound, like hydrochloric acid, to hundreds or thousands in more complex substances. The word atom can only be used in speaking of an elementary body, and that only while it is passing through a reaction. The term molecule apyplies indifferently to elements and compounds. The atoms have definite relative weights ; and upon an exact determi- nation of these weights depends the entire science of quantitative analyti- cal chemistry. They have been determined by repeated and careful analyses of perfectly pure compounds of the elements, and express the iveight of one atom of the element as compared ivith the iveight of one atom of hydrogen, that being the lightest element known. It is also the weight of a volume of the element, in the form of gas, which would occupy the same volume, under like pressure and temperature, as an amount of hydrogen weighing one. What the absolute weight of an atom of any element may be we do not know, nor would the knowledge be of any service did we possess it. The following table contains a list of the elements at present known, with their atomic weights : ELEMENTS. Name. A. Symbol. B. Atomic weight. Name. A. Symbol. B. Atomic weight. Aluminium Al. 27.02 Hvdrogen H. 1 Autimonv Sb. 120 Indium In. 113.4 Arsenic As. 74.9 Iodine I. 126.85 Barium Ba. 136.8 Iridium Ir. 192.7 Bismuth Bi. 206.5 Iron Fe. 55.9 Boron Bo. 11 Lantliauium La. 138.5 Bromine Br. 79 952 Lead Pb. 206 92 Cadmium Cd. 111.8 Lithium Li. 7 Caesium Cs. 132.6 Magnesium Mg. 24 Calcium Ca 40 Manganese Mn. 54 Carbon C. 11.974 Mercury Hg. 199 7 Cerium Ce. 141 Molybdenum Mo. 95.5 Chlorine .. Cl. 35 457 Nickel Ni. 58 Cr. 52.4 Niobium Nb. 94 Cobalt Co. 58.9 Nitrogen N. 14.044 Copper Cu. 63.2 Osmium Os. 198.5 Didymium D’. 144.78 Oxvgen 0. 16 Erbium E. 165.9 Palladium Pd. 105.7 Fluorine FI. 19 Phosphorus P. 31 Gallium Ga. 68.8 Platinum Pt. 194.4 Glucinum Gl. 9 Potassium K. 39.137 Gold Au. 196.2 Rhodium Rli. 104.1 ATOMIC AND MOLECULAR WEIGHTS. 13 ELEMENTS.—Continued. Name. A. Symbol. B. Atomic weight. Name. A. Symbol. B. Atomic weight. Rubidium Rb. 85.3 Thallium Tl. 203.7 Ruthenium Ru. 104.2 I Thorium Th 233 Scandium Sc. 44 Tin Sn. 117.7 Selenium. Se. 78.8 Titanium Ti 49.85 Silicon Si. 28 Tungsten W. 183.6 Ag. 107.675 Uranium u. 238.5 Sodium Na. 22.998 ■ Vanadium V. 51.3 Strontium Sr. Ytterbium Yb. 172.7 s 31.984 Yttrium Y. 89.8 Tantalum Ta. 182 Zinc .... Zn. 64.9 Tellurium Te. 128 Zirconium Zr. 89.6 In some cases the results of analyses are such as would agree with two values as the atomic weight of an element equally well. In this case we can decide which is the correct value by the law of Dulong and Petit. These observers found that while the atomic weights of the elements vary greatly from each other, the specific heats (see p. 33) differ from each other in an opposite manner, and to such an extent that the product ob- tained by multiplying the two together does not vary much from 6.4. This product is known as the atomic heat. When by analysis it is not pos- sible to determine which of two numbers is the correct atomic weight of an element, that one is selected which, when multiplied by the specific heat, gives a result most nearly approaching 6.4. The atomic heats of boron, carbon, silicon, sulphur, and phosphorus are subject to great variations, as is shown in the following table : Specific Atomic heat. heat. Boron. Crystallized at — 39.6°.... .... 0.1915 2.11 Crystallized at + 16.7°.... .... 0.2737 3.01 Crystallized at + 233.2° .... 0.3663 3.99 Amorphous. ... 0.255 2.81 Specific Atomic heat. heat. Silicon. Crystallized at — 39.8°... ... 0.1360 3. SI Crystallized at -f” 128.7°... . . 0.1964 5.50 Crystallized at + 232.4°... ... 0.2029 5.68 Fused at -j- 190° ... ... 0.175 4.90 Sulphur. Orthorhombic at + 45° ... ... 0.163 5.22 Orthorhombic at + 99° ... ... 0.1776 5.68 Liquid at + 150° ... ... 0.234 7.49 Recently fused at -j- 98° ... ... 0.20259 6.48 Phosphorus. Yellow at — 78° ... ... 0.174 5.39 Yellow at -f- 30° ... ... 0.202 6.26 Liquid at + 100° ... ... 0.212 tf.57 Amorphous at -j- 93° ... ... 0.170 5.27 Carbon’. Diamond at — 50.5° 0.0635 0.76 Diamond at + 140° 0.2218 2.66 Diamond at -j- 985° 0.4589 5.51 Graphite at- 50.3® 0.1138 1.37 Graphite at + 138.5° 0.2542 3.05 Graphite at 4- 977.9° 0.4670 5.60 Wood charcoal 0.2415 2.90 It will be observed that, as the temperature of the solid element is in- creased, the atomic heat more nearly approaches 6.4. It will further be noticed that those elements with which the perturbations occur are those which are capable of existing in two or more allotropic forms (see p. 31). As in the passage of an element from one allotropic condition to another, absorption or liberation of heat always takes place, as the result of “inte- rior work ; ” it is probable that these perturbations are due to a constant tendency of the element to pass from one allotropic condition to another. 14 MANUAL OF CIIEMISTKY. The atomic heats of those elementary gases which have only been liquified by enormous cold and pressure are tolerably constant at about 2.4. Molecular Weight.—The molecular weight of a substance is the weight of its molecule as compared with the weight of an atom of hydrogen. It is also, obviously, the sum of the weights of all the atoms making up the molecule. A very ready means of determining the molecular weight of any sub- stance which we can convert into a gas is based upon Avogadro’s law. The sp. gr. of a gas is the weight of a given volume as compared with that of an equal volume of hydrogen. But these equal volumes contain equal numbers of molecules (p. 11), and therefor, in determining the sp. gr. of a gas, we obtain the weight of its molecule as compared with that of a molecule of hydrogen ; and, as the molecule contains two atoms of hy- drogen, while one atom of hydrogen is the unit of comparison, it follows that the specific gravity of a gas, multiplied by two, is its molecular weight. For example, the gas acetylene and the liquid benzene each contain 92.31 per cent, of carbon, and 7.G9 per cent, of hydrogen; which is equiv- alent to 24 parts, or two atoms of carbon ; and 2 parts, or two atoms of hydrogen. The sp. gr. of acetylene, referred to hydrogen = 2, is 13 ; its molecular weight is, therefor, 2G, and its molecule contains two atoms of carbon and two atoms of hydrogen. The sp. gr. of vapor of benzene is 39 ; its molecular weight is, therefor, 78, and its molecule contains six atoms of carbon and six atoms of hydrogen. The vapor densities of comparatively few elements are known : Hydrogen Vapor density. 1 Atomic weight. 1 Molecular weight. 2 Oxygen 16 16 32 Sulphur 32 32 64 Selenium 82 79 164 Tellurium 130 128 260 Chlorine 35.5 35.5 71 Bromine 80 80 160 Vapor Atomic Molecular density. weight. weight. Iodine ...... 121 127 254 Phosphorus (53 31 126 Arsenic 150 75 300 Nitrogen 14 14 28 39 78 Cadmium 56 112 112 Mercury 100 200 200 The atomic weight being, in most of the above instances, equal to the vapor density, and to half the molecular weight, it may be inferred that the molecules of these elements consist of two atoms. Noticeable discrep- ancies exist in the case of four elements. The molecular weights of phosphorus and arsenic, as obtained from their vapor densities, are not double but four times as great as their atomic weights. The molecules of phosphorus and arsenic are, therefor, supposed to contain four atoms. Those of cadmium and mercury contain but one atom. Valence or Atomicity. It is known that the atoms of different elements possess different powers of combining with and of replacing atoms of hydrogen. Thus : One atom of chlorine combines with one atom of hydrogen, One atom of oxygen combines with two atoms of hydrogen, One atom of nitrogen combines with three atoms of hydrogen, One atom of carbon combines with four atoms of hydrogen. The valence, atomicity, or equivalence of an element is the saturating 'power of one of its atoms as compared with that of one atom of hydrogen. Elements may be classified according to their valence into— VALENCE OR ATOMICITY 15 Univalent elements or monads Cl' Bivalent elements or dyads O ' Trivalent elements or triads B" Quadrivalent elements or tetrads Clv Quinquivalent elements or pentads Pv Sexvalent elements or liexads Wvi Elements of even valence, i.e., those which are bivalent, quadrivalent, or sexvalent, are sometimes called artiads ; those of uneven valence being designated as perissads. In notation the valence is indicated, as above, by signs placed to the right and above the symbol of the element. But the valence of the elements is not fixed and invariable. Thus, while chlorine and iodine each combine with hydrogen, atom for atom, and in those compounds are consequently univalent, they unite with each other to form two compounds—one containing one atom of iodine and one of chlorine, the other containing one atom of iodine and three of chlorine. Chlorine being univalent, iodine is obviously trivalent in the second of these compounds. Again, phosphorus forms two chlorides, one contain- ing three, the other five atoms of chlorine to one of phosphorus. In view of these facts, we must consider, either: 1, that the valence of an element is that which it exhibits in its most saturated compounds, as phosphorus in the pentaclaloride, and that the lower compounds are non- saturated and have free valences ; or 2, that the valence is variable. The first supposition depends too much upon the chances of discovery of com- pounds in which the element has a higher valence than that which might be considered as the maximum to-day. The second supposition—notwith- standing the fact that, if we admit the possibility of two distinct valences, we must also admit the possibility of others—is certainly the more tenable and the more natural. In speaking, therefor, of the valence of an element, we must not consider it as an absolute quality of its atoms, but simply as their combining power in the particular class of compounds under consideration. Indeed, compounds are known in whose molecules the atoms of one ele- ment exhibit two distinct valences ; thus, ammonium cyanate contains two atoms of nitrogen : one in the ammonium group is quinquivalent, one in the acid radical is trivalent. When an element exhibits different valences, these differ from each other by two. Thus, phosphorus is trivalent or quinquivalent; platinum is bivalent or quadrivalent. Symbols—Formulae—Equations. Symbols.—These are conventional abbreviations of the names of the elements, whose purpose it is to introduce simplicity and exactness into descriptions of chemical actions. They consist of the initial letter of the Latin name of the element, to which is usually added one of the other letters. If there be more than two elements whose names begin with the same letter, the single-letter symbol is reserved for the commonest ele- ment. Thus, we have nine elements whose names begin with C ; of these the commonest is Carbon, whose symbol is C ; the others have double- letter symbols, as Chlorine, Cl; Cobalt, Co ; Couper, Cu (Cuprum), etc. These symbols do not indicate simply an indeterminate quantity, but one atom of the corresponding element. 16 MANUAL OF CHEMISTRY. When more than one atom is spoken of, the number of atoms which it is desired to indicate is written either before the symbol or, in small figures, after and below it; thus, H indicates one atom of hydrogen ; 2C1, two atoms of chlorine ; C4, four atoms of carbon, etc. Formulae.—What the symbol is to the element, the formula is to the compound ; by it the number and kind of atoms of which the molecule of a substance is made up are indicated. The simplest kind of formulae are what are known as empirical formulae, which indicate only the kind and number of atoms which form the compound. Thus, HC1 indicates a mole- cule composed of one atom of hydrogen united with one atom of chlorine ; 5H..O, five molecules, each composed of two atoms of hydrogen and one atom of oxygen, the number of molecules being indicated by the proper numeral placed before the formula, in which place it applies to all the symbols following it. Sometimes it is desired that a numeral shall apply to a part of the symbols only, in which case they are enclosed in parenthe- ses ; thus, Al2 (S04)3 means twice A1 and 3 times S04. For other varieties of formulae, see p. 23. Equations are combinations of formulae and algebraic signs so arranged as to indicate a chemical reaction and its results. The signs used are the plus and equality signs ; the former being equivalent to “ and,” and the second meaning “ have reacted upon each other and have produced.” The substances entering into the reaction are placed before the equality sign, and the products of the reaction after it; thus, the equation 2KH0 + H2S04= Iv S04 + 2H_0 means, wdien translated into ordinary language : two molecules of potash, each composed of one atom of potassium, one atom of hydrogen, and one atom of oxygen, and one molecule of sulphuric acid, composed of one atom of sulphur, four atoms of oxygen, and two atoms of hydrogen, have reacted upon each other and have p)roduced one molecule of potassium sulphate, composed of one atom of sulphur, four atoms of oxygen, and two atoms of potassium, and two molecules of water, each composed of two atoms of hydrogen and one atom of oxygen. As no material is ever lost or created in a reaction, the number of each kind of atom occurring before the equality sign in an equation must al- ways be the same as that occurring after it. Electrolysis. When a galvanic current of sufficient, power is made to pass through a compound liquid, or a solution of a compound capable of conducting the current, a decomposition of the compound almost invariably ensues. The terminals by which the current is conducted into the liquid are known as the poles or electrodes, and for this purpose are best made of sheets of platinum. The pole connected with the copper, carbon, or platinum end of the battery is known as the positive pole; that connected with the zinc end as the negative pole. The decomposition by the voltaic current is known as electrolysis, and the liquid subjected to decomposition is called an electrolyte. When compounds are subjected to electrolysis the constituent ele- ments are not discharged throughout the mass, although the decomposition occurs at all points between the electrodes. In compounds made up of ELECTROLYSIS. 17 two elements only, binary compounds, one element is given off at each of the poles, entirely unmixed with the other, and always from the same pole. Thus, if hydrochloric acid be subjected to electrolysis, pure hydrogen is given off at the negative pole and pure chlorine at the positive pole. In the case of compounds containing more than two elements, a simi- lar decomposition occurs; one element being liberated at one pole and the remaining group of elements separating at the other. This primary decomposition is frequently modified as to its final products by intercur- rent chemical reactions ; indeed, the group of elements liberated at one pole is rarely capable of separate existence. When, for instance, a solu- tion of potassium sulphate is subjected to electrolysis the liquid in the arm of the tube connected with the positive pole becomes acid in reac- tion, and gives off oxygen ; at the same time the liquid on the negative side becomes alkaline, and gives off a volume of hydrogen double that of the oxygen liberated. In the first place, the potassium sulphate molecule is decomposed into potassium and the group S04: K.,S04 = S04 + Ka. The potassium liberated at the negative pole immediately decomposes the surrounding water, forming potash and liberating hydrogen ; and the group SO, liberated at the positive pole immediately reacts with water to form sulphuric acid and liberate oxygen : K2 + 2H20 = 2KHO + H2 and S04 + H20 = H2SO, + O. In the electrolysis of chemical compounds the different elements and groups of elements, such as SO, in the example given above, known as residues or radicals, seem to be possessed of definite electrical characters, and are given off at one or the other pole in preference. Those which are given off at the positive or platinum pole are supposed to be negatively electrified, and are therefor known as electro-negative or acidulous ele- ments or residues; those given off at the negative pole, being positively electrified, are known as electro-positive or basylous elements or residues. The following are the electrical characters of the principal elements and residues: Electro-negative or Acidulous. Oxygen, Molybdenum, Sulphur, Tungsten, Nitrogen, Boron, Chlorine, Carbon, Iodine, Antimony, Fluorine, Tellurium, Phosphorus, Niobium, Selenium, Titanium, Arsenic, Silicon, Chromium, Osmium, . Electropositive or Basylous. Hydrogen, Nickel, Potassium, Cobalt, Sodium, Cerium, Lithium, Lead, Barium, Tin, Strontium, Bismuth, Calcium, Uranium, Magnesium, Copper, Glucinium, Silver, Yttrium, Mercury, Aluminium, Palladium, Zirconium, Platinum, Manganese, Rhodium, Zinc, Iridium, Cadmium, Gold, Iron, Alcoholic radicals. Residues of acids remaining after the removal of a number of hydro- gen atoms equal to the basicity of the acid. i 18 MANUAL OF CHEMISTRY. Acids, Bases, and Salts. An acid is a compound of an electro-negative element or residue with hy- drogen ; ivhich hydrogen it can part with in exchange for an electropositive element without formation of a base. An acid may also be defined as a com- poundbody which evolves water by its action upon pure caustic potash or soda. No substance which does not contain hydrogen can, therefor, be called an acid. The basicity of an acid is the number of replaceable hydrogen atoms con- tained in its molecule. A monobasic acid is one containing a single replaceable atom of hy- drogen, as nitric acid, HN03; a dibasic acid is one containing two such re- placeable atoms, as sulphuric acid, H.,S04; a tribasic acid is one containing three replaceable hydrogen atoms, as phosphoric acid, H P04. Polybasic acids are such as contain more than one atom of replaceable hydrogen. Hydracids are acids containing no oxygen ; oxacids or oxyacids contain both hydrogen and oxygen. The term base is regarded by many authors as applicable to any com- pound body capable of neutralizing an acid ; it is, however, more consist- ent with modern views to limit the application of the name to such com- pound substances as are capable of entering into double decomposition with acids to form salts and water. They may be considered as one or more molecules of water in which one-half of the hydrogen has been replaced by an electro-positive element or radical; or as compounds of such ele- ments or radicals with one or more groups, OH. Being thus considered as derivable from water, they are also known as basic hydrates. They have the general formula, My (OH)„. They are monatomic, diatomic, tri- atomic, etc., according as they contain one, two, three, etc., groups oxhy- dryl (OH). A double decomposition is a reaction in which both of the reacting com- pounds are decomposed to form two new compounds. Sulphobases, or hydrosulphides, are compounds in all respects resem- bling the bases, except that in them the oxygen of the base is replaced by sulphur. Salts are substances formed by the substitution of basylous radicals or ele- ments for a part or all of the replaceable hydrogen of an acid, They are always formed, therefor, when bases and acids enter into double decompo- sition. They are not, as was formerly supposed, formed by the union of a metallic with a non-metallic oxide, but, as stated above, by the substitu- tion of one or more atoms of an element or radical for the hydrogen of the acid. Thus, the compound formed by the action of sulphuric acid upon quicklime is not S03CaO, but CaS04, formed by the interchange of atoms : s 04 < (Ca H2 > O °. < (§a <— (5- and not it is, therefor, calcium sulphate, and not sulphate of lime. ACIDS, BASES, AND SALTS. 19 The term salt, as used at present, applies to the compound formed by the substitution of another element for the hydrogen of any acid ; and in- deed, as used by some authors, to the acids themselves, which are con- sidered as salts of hydrogen. It is probable, however, that eventually the name will be limited to such compounds as correspond to acids whose molecules contain more than two elements. Indeed, from the earliest times of modern chemistry a distinction has been observed between the haloid salts, i.e., those the molecules of whose corresponding acids con- sisted of hydrogen united with one other element, on the one hand ; and the salts of the oxacids, i.e., those into whose composition oxygen en- tered, on the other hand. This distinction, however, has gradually fallen into the background, for the reason that the methods and conditions of formation of the two kinds of salts are usually the same when the basylous element belongs to that class usually designated as metallic. There are, however, important differences between the two classes of compounds. There exist compounds of all of the elements correspond- ing to the hydracids, binary compounds of chlorine, bromine, iodine, and sulphur. There is, on the other hand, a large class of elements which are incapable of forming salts corresponding to the oxacids ; no salt of an oxacid with any one of the elements usually classed as metalloids (except- ing hydrogen) has been obtained. Haloid salts may be formed by direct union of their constituent ele- ments ; oxysalts are never so produced. Action of Acids and Bases on Salts, and of Salts on each other. If an acid be added to a solution of a salt whose acid it nearly ecpmls in chemical activity, the salts of both acids and the free acids themselves will probably exist in the solution, provided both acids and salts are solu- ble. Thus : 2H2S04 + 3KN03 = K2S04 + KN03 + H2S04 + 2HN03 Sulphuric acid. Potassium nitrate. Potassium sulphate. Potassium nitrate. Sulphuric acid. Nitric acid. If an acid be added to a solution of a salt whose acid it greatly exceeds in activity, the salt is decomposed, with formation of the salt of the stronger acid and liberation of the weaker acid ; both acids and salts being soluble : HS04 + 2C,H,02Na = Na2S04 + 2C,H30,H Sulphuric acid. Sodium acetate. Sodium sulphate. Acetic acid. If to a solution of a salt whose acid is insoluble in the solvent used, an acid be added capable of forming a soluble salt with the basylous element, such soluble salt is forhied and the acid is deposited : Sulphuric acid. H..SO. + 2C„H,ANa = Na.SC). + 2C„H..O,H Sodium stearate. Sodium sulphate. Stearic acid. If to a salt whose acid is volatile at the existing temperature, an acid capable of forming with the basylous element a salt fixed at the same temperature be added, the fixed salt is formed and the volatile acid ex- pelled. Thus, with the application of heat: Sulphuric acid. H2S04 + 2NaN03 = Na2S04 + 2HN03 Sodium nitrate. Sodium sulphate. Nitric acid. 20 MANUAL OF CHEMISTRY. If to a solution of a salt an acid be added which is capable of forming an insoluble salt with the base, such insoluble salt is formed and precipi- tated : Sulphuric acid. H2S04 + Ba(N03), = BaS04 -f 2HNOs Barium nitrate. Barium sulphate. Nitric acid. If to a solution of a salt whose basylous element is insoluble a soluble base is added, capable of forming a soluble salt with the acid, such soluble salt is formed, with precipitation of the insoluble base : Cupric sulphate. CuSO, + 2KHO = Iv2S04 + CuH„02 Potassium hydrate. Potassium sulphate. Cupric hydrate. If a base be added to a solution of a salt with whose acid it is capable of forming an insoluble salt, such insoluble salt is formed and precipitated, and the base of the original salt, if insoluble, is also precipitated : BaH20, + K,S04 = BaS04 + 2KHO Barium hydrate. Potassium sulphate. Barium sulphate. Potassium hydrate. Barium hydrate. BaH.,0, + Ag9S04 = BaS04 + 2AgHO Silver sulphate. Barium sulphate. Silver hydrate. When solutions of two salts, the acids of both of which form soluble salts with both bases, are mixed, the resultant liquid contains the four salts: 3Iv„S04 + 3NaN03 = 2K.,S04 + Na2S04 + 2KN03 + NaN03 Potassium sulphate. Sodium nitrate. Potassium sulphate. Sodium sulphate. Potassium nitrate. Sodium nitrate. or in some other proportion. If solutions of two salts, the acid of one of which is capable of uniting with the base of the other to form an insoluble salt, are mixed, such in- soluble salt is precipitated: Ba(N0.()2 + Na2S04 = BaS04 + 2NaNOs Barium nitrate. Sodium sulphate. Barium sulphate. Sodium nitrate. Nomenclature. The names of the elements are mostly of Greek derivation, and have their origin in some prominent property of the substance ; thus, phos- phorus, <£u>s, light, and cfrepeiv, to bear. Some are of Latin origin, as silicon, from silex, flint; some of Gothic origin, as iron, from iarn ; and others are derived from modern languages, as potassium, from pot-ash. Very little system has been followed in naming the elements, beyond applying the termination ium to the metals, and ine or on to the metalloids ; and even to this rule we find such exceptions as a metal called manganese and a metalloid called sulphur. The names of compound substances were formerly chosen upon the same system, or rather lack of system, as those of the elements. So long as the number of compounds with which the chemist had to deal remained small, the use of these fanciful appellations, conveying no more to the mind than perhaps some unimportant quality of the substances to which they applied, gave rise to compai’atively little inconvenience. In these NOMENCLATURE. 21 later days, however, when the number of compounds has risen high in the thousands, some systematic method has become absolutely necessary. The principle at the base of the system of nomenclature at present used is that the name shall itself convey, as far as possible, the composition and character of the substance. Compounds consisting of two elements, or of an element and a radical only, binary compounds, are designated by compound names made up of the name of the more electro-positive, followed by that of the more elec- tro-negative, in which the termination ide has been substituted for the terminations ine, on, ogen, ygen, or us, ium, and ur. For example : the compound of potassium and chlorine is called potassium chloride, that of potassium and oxygen, potassium oxide, that of potassium and phos- phorus, potassium phosphide. In a few instances the older name of a compound is used in preference to the one which it should have under the above rule, for the reason that the substance is one which is typical of a number of other substances, and therefor deserving of exceptional prominence ; such are ammonia, NH3 ; water, H.,0. When, as frequently happens, two elements unite with each to form more than one compound, these are usually distinguished from each other by prefixing to the last word of the name the Greek numeral correspond- ing to the number of atoms of the element designated by that word, as compared with a fixed number of atoms of the other element. Thus, in the series of compounds of nitrogen and oxygen, most of which contain two atoms of nitrogen, N„ is the standard of comparison, and consequently the names are as follows : N.,0 =Nitrogen monoxide. NO (=N20.,) =Nitrogen dioxide. N203 — Nitrogen trioxide. N.,0 (=N204)=Nitrogen te/roxide. N205 = Nitrogen pentoxide. Another method of distinguishing two compounds of the same two elements consists in terminating the first word in ous, in that compound which contains the less proportionate quantity of the more electro-nega- tive element, and in ic in that containing the greater proportion ; thus : SO,, = Sulphurous oxide, S03 = Sulphuric oxide. Hg202 (2Hg : 2C1) = Mercurous chloride. HgCl2 (2Hg : 40)=Mercuric chloride. This method, although used to a certain extent in speaking of compounds composed of two elements of Class II. (see p. 27), is used chiefly in speak- ing of binary compounds of elements of different classes. In naming the oxacids the word acid is used, preceded by the name of the electro-negative element other than oxygen, to which a prefix or suffix is added to indicate the degree of oxidation. If there be only two, the least oxidized is designated by the suffix ous, and the more oxidized by the suffix ic, thus : HNO„ = Nitrous acid. HN03 = Nitric acid. 22 MANUAL OF CHEMISTRY. If there be more than two acids, formed in regular series, the least oxi- dized is designated by the prefix hypo and the suffix ous ; the next by the suffix ous; the next by the suffix ic ; and the most highly oxidized by the prefix per and the suffix ic ; thus : HCIO = Hypochlovous acid. HCIO, = Chlorous acid. HC103 = Chloric acid. HC104 = Perchloric acid. Certain elements, such as sulphur and phosphorus, exist in acids which are derived from those formed in the regular way, and which are specially designated. The names of the oxysalts are derived from those of the acids by drop- ping the word acid, changing the termination of the other word from ous into ite, or from ic into ate, and prefixing the name of the electro-positive element or radical; thus : H2so3 Sulphurate acid. K,so3 Potassium sulphide. H,S04 Sulphuric acid. K,S04 Potassium sulphate. HCIO Hypochlorows acid. KC10 Potassium hypochlori/e. Acids whose molecules contain more than one atom of replaceable hy- drogen are capable of forming more than one salt with electro-negative elements, or radicals, whose valence is less than their basicity. Ordinary phosphoric acid, for instance, contains in each molecule three atoms of basic hydrogen, and consequently is capable of forming three salts by the replacement of one, two, or three of its hydrogen atoms by one, two, or three atoms of a univalent element; to distinguish these the Greek pre- fixes mono, di, and tri are used, thus : H„KP04 = d/ouopotassic phosphate. HK,P04 = Uipotassic phosphate. K3P04 = IVipotassic phosphate. The first is also called ifi/iyifropotassic phosphate, and the second, hydrodi- potassic phosphate. In the older works, salts in which the hydrogen has not been entirely displaced are sometimes called iiisalts (bicarbonates), or acid salts ; those in which the hydrogen has been entirely displaced being designated as neutral salts. Some elements, such as mercury, copper, and iron, form two distinct series of salts ; these are distinguished, in the same way as the acids, by the use of the suffix ous in the names of those containing the less propor- tion of the electro-negative group, and the suffix ic in those containing the greater proportion, e.g.: (Cu2),2S04 (1S04 : 4Cu) = Cuprous sulphate. Cu2S04 (2S04 : 4Cu) = Cupric sulphate. FeSO, (2S04 : 2Fe) = Ferrous sulphate. (FeJ(S04)3 (3S04 : 2Fe) = Ferric sulphate. CONSTITUTION. TYPICAL AND GRAPHIC FORMULAE. 23 The names, basic salts, su&salts, and oarysalts have been applied in- differently to salts, such as the lead subacetates, which are compounds containing the normal acetate and the hydrate or oxide of lead ; and to salts such as the so-called bismuth subnitrate, which is a nitrate, not of bismuth, but of the univalent radical (Bi'"0')'. By double salts are meant such as are formed by the substitution of different elements or radicals for two or more atoms of replaceable hydro- gen of the acid, such as ammonio-magnesian phosphate, PO.Mg" (NH4)'. Radicals. A radical, or compound radical, is a non-saturatea group of atoms which behaves like an atom of an element. Such radicals are capable of passing from one compound into another, and are sometimes, although rarely, cap- able of separate existence. Marsh gas has the composition CH( ; bv act- ing upon it in suitable ways we can cause the atom of carbon, accompanied by three of the hydrogen atoms, to pass into a variety of other compounds, such as : (CH.,)C1; (CH,)OH ; (CHs),0; C3H302(CH3). Marsh gas, there- for, consists of the radical (CH3) combined with an atom of hydrogen : (CH,)'H. It is especially among the compounds of carbon that the existence of radicals comes into prominent notice ; they, however, occur in inorganic substances also ; thus the nitric acid molecule consists of the radical N03, combined with the group OH. Like the elements, the radicals possess different valences, depending always upon the number of unsatisfied valences which they contain. Thus the radical (CH,) is univalent, because three of the four valences of the carbon atom are satisfied by atoms of hydrogen, leaving one free valence ; the radical (PO) of phosphoric acid is trivalent, because two of the five valences of the phosphorus atom are satisfied by the two valences of the bivalent oxygen atom, leaving three free valences. In notation the radicals are usually enclosed in brackets, as above, to indicate their nature. The names of radicals terminate in yl or in gen; thus : (CH.,) = methyl; (CN) = cyanogen. The terms radical and residue, although sometimes used as synonyms, are not such in speaking of electrical decompositions (see p. 17). Thus the radical of sulphuric acid is S02; but when sulphuric acid is electrolyzed it is decomposed into hydrogen and the residue S04. Constitution. Typical and Graphic Formulae. The composition of a compound is the number and kind of atoms con- tained in its molecule ; and is shoion by its empirical formula. The constitution of a compound is the number and kind of atoms and their relations to each other, within its molecule ; and is shown by its typical or graphic formula. The characters of a compound depend not only upon the kind and number of its atoms, but also upon the manner in which they are attached to each other, upon their constitution. There are, for instance, two sub- stances, each having the empirical formula C,H,0.,, one of which is a strong acid, the other a neutral ether. As the molecule of each contains the same number and kind of atoms, the differences in their properties MANUAL OF CHEMISTRY. must be due to differences in the manner in which the atoms are linked together. In the system of typical formulae all substances are considered as being so constituted that their rational formulae may be referred to one of three classes or types, or to a combination of two of these types. These three classes, being named after the most common substance occurring in each, are expressed thus : The hydrogen The water The ammonia type. type. type. Hl !}° H) Hf Hf N H) H.J II0- H.J HJ h2ns etc., etc., HJ etc., it being considered that the formula of any substance of known consti- tution can be indicated by substituting the proper element, or radical, for one or more of the atoms of the type, thus : Cl) Hj (C,HJ|0 (C,h5)') H )- N Hi Cl,) Ca j (SO,)" ) HJOs (CO)") hJn, H,) Hydrochloric acid. Alcohol. Ethylamine. Calcium chloride. Sulphuric acid. Urea. Typical formulas are of great service in the classification of compound substances, as well as to indicate, to a certain degree, their nature and the method of the reactions into which they enter. Thus in the case of the two substances mentioned above as both having the composition we find on examination that one contains the group (CIlJ', while the other contains the group (C2HaO)', united to one atom of replaceable hydrogen. The difference in their constitution at once becomes apparent in their typical formulas, | O and j O, indicating differ- ences in their properties, which we find upon experiment to exist. The first substance is neutral in reaction and possesses no acid properties ; it closely l'esembles a salt of an acid having the formula j O. The second substance, on the other hand, has a strongly acid reaction, and markedly acid properties, as indicated by the oxidized radical and the extra-radical hydrogen. It is capable of forming salts by the substitution of an atom of a univalent, basylous element for its single replaceable atom of hydrogen : (C2H30)' ) Q Na i Although typical formulas have been, and still are, of great service, many cases arise, especially in treating of the more complex organic sub- stances, in which they do not sufficiently indicate the relations between the atoms which constitute the molecule, and thus fail to convey a proper idea of the nature of the substance. Considering, for example, the ordi- nary lactic acid, we find its composition to be CsHcOs, which, expressed /Q JJ Q\" | typically, would be ;i 1 | 02, a constitution supported by the fact CONSTITUTION. TYPICAL AND GRAPHIC FORMULAE. 25 that the radical (C3H40)r may be obtained in other compounds, as 1C H 0),( ) ' 3 4 (ji ' • This constitution, however, cannot be the true one, because in the first place, lactic acid is not dibasic, but monobasic ; and, in the second place, there is another acid, called paralactic acid, having an iden- tical composition, yet differing in its products of decomposition. These differences in the properties of the two acids must be due to a different arrangement of atoms in their molecules, a view which is supported by the sources from which they are obtained and the nature of their products of decomposition. To express the constitution of such bodies, graphic formulas are used, in which the position of each atom in relation to the others is set forth. The constitution of the two lactic acids would be expressed by graphic formulae in this way : /H C—H \H -i /II | \0—H Jv'o —H /H C—H \0—H 0/H [XH U/o H and or, ch3 I CH.OH I CO.OH CHOH I CH, I CO.OH and Ordinary lactic acid. Paralactic acid. It must be understood that these graphic formula? are simply in- tended to show the relative attachments of the atoms, and are in nowis® intended to convey the idea that the molecule is spread out upon a flat surface with the atoms arranged as indicated in the diagram. Great care and much labor are required in the construction of these graphic formulae, the positions of the atoms being determined by a close study of the methods of formation, and of the products of decomposition of the substance under consideration. Naturally, in a matter of this na- ture, there is always room for differences of opinion—indeed, the entire atomic theory is open to question, as is the theory of gravitation itself. But, whatever may be advanced, two facts cannot be denied: first, that chemistry owes its advancement within the past half-century to the atomic theory, which to-day is more in consonance with observed facts than any substitute which can be offered ; second, that without the use of graphic formula? it is impossible to offer any adequate explanation of the reac- tions which we observe in dealing with the more complex organic sub- stances. In chemistry, as in other sciences, a sharp distinction must always he made between facts and theory: the former, once observed, are immut- able additions to our knowledge ; the latter are of their nature subject to change with our increasing knowledge of facts. We have every reason for believing, however, that the supports upon which the atomic theory 26 MANUAL OF CHEMISTRY. rests are such that, although it may be modified in its details, its essential features will remain unaltered. Classification of the Elements. Berzelius was the first to divide all the elements into two great classes, to which he gave the names metals and metalloids. The metals, being such substances as are opaque, possess what is known as metallic lustre, are good conductors of heat and electricity, and are electro-positive ; the metal- loids, on the other hand, such as are gaseous, or, if solid, do not possess metallic lustre, have a comparatively low power of conducting heat and electricity, and are electro-negative. This division, based purely upon physical properties, which, in many cases, are ill-defined, has become insufficient. . Several elements formerly classed under the above rules with the metals, resemble the metalloids in their chemical characters much more closely than they do any of the metals ; indeed, by the characters mentioned above, it is impossible to draw any line of demarcation which shall separate the elements distinctly into two groups. The classification of the elements should be such that each group shall contain elements whose chemical properties are similar—the physical prop- erties being considered only in so far as they are intimately connected with the chemical (see p. 13). The arrangement of elements into groups is not equally easy in all cases ; some groups, as the chlorine group, are sharply defined, while the members of others differ from each other more widely in their properties. The positions of most of the more recently discovered elements are still uncertain, owing to the imperfect state of our knowledge of their properties. The method of classification which we will adopt, and which we be- lieve to be more natural than any hitherto suggested, is based upon the chemical properties of the oxides and upon the valence of the elements. We abandon the division into metals and metalloids, and substitute for it a division into four great classes, according to the nature of the oxides and the existence or non-existence of oxysalts. In the first of these classes hydrogen and oxygen are placed together, for the reason that, although they differ from each other in many of their properties, they together form the basis of our classification, and may, for this and other reasons, be regarded as typical elements. They both play important parts in the formation of acids, and neither would find a suitable place in either of the other classes. Our primary division would then be as follows : Class I.—Typical elements. Class II.—Elements whose oxides unite with xoater to form acids, never to form, bases. Which do not form oxysalts. This class contains all the so-called metalloids except hydrogen and oxygen. Class III.—Elements whose oxides unite with water, some to form bases, others to form acids. Which form oxysalts. Class IV.—Elements whose oxides unite with water to form bases; never to form acids. Which form oxysalts. In this class are included the more strongly electro-positive metals. Within the classes a further subdivision is made into groups, each group containing those elements within the class which have equal va- PHYSICAL CHARACTERS OF CHEMICAL INTEREST. 27 lences, which form corresponding compounds, and whose chemical charac- ters are otherwise similar. For the sake of convenience the term metal is retained to apply to the members of Classes IH. and IV. ; the term non-metal being used for those belonging to Class H. Class I. Group I.—Hydrogen. Group II.—Oxygen. Class II. Group I.—Fluorine, chlorine, bromine, iodine. Group II.—Sulphur, selenium, tellurium. Group III.—Nitrogen, phosphorus, arsenic, antimony. Group IV.—Boron. Group V.—Carbon, silicon. Group VI.—Vanadium, niobium, tantalium. Group VII.—Molybdenum, tungsten, osmium (?). Group I. —Gold. Group II.—Chromium, manganese, iron. Group III.—Glucinium, aluminium, scandium, gallium, indium. Group IY.—Uranium. Group V.—Lead. Group VI.—Bismuth. Group YII.—Titanium, zirconium, tin. Group VIII.—Palladium, platinum. Group IX.—Rhodium, ruthenium, iridium. Class III. Class TV. Group I.—Lithium, sodium, potassium, rubidium, c;esium, silver. Group II.—Thallium. Group III.—Calcium, strontium, barium. Group IV.—Magnesium, zinc, cadmium. Group V.—Nickel, cobalt. Group VI.—Copper, mercury. Group VII.—Yttrium, cerium, ytterbium, lantlianium, didymium, er- bium. Group VIII.—Thorium. Physical Characters of Chemical Interest. Crystallization.—Solid substances exist in two forms, amorphous and crystalline. In the former they assume no definite shape ; they con- duct heat equally well in all directions ; they break irregularly; and, if transparent, allow light to pass through them equally well in all direc- tions. A solid in the crystalline form has a definite geometrical shape ; conducts heat more readily in some directions than in others ; when 28 MANUAL OF CHEMISTRY. broken, separates in certain directions, called j)lanes of cleavage, more readily than in others ; and modifies the course of luminous rays passing through it differently when they pass in certain directions than when they pass in others. Crystals are formed in one of four ways : 1.) An amorphous substance, Fig. 7. by slow and gradual modification, may assume the crystalline form ; as vitreous arsenic trioxide (q. v.) passes to the crystalline variety. 2.) A fused solid, on cooling, crystallizes ; as bismuth. 3.) When a solid is sub- limed it is usually condensed in the form of crystals. Such is the case with arsenic trioxide. 4.) The usual method of obtaining crystals is by the evaporation of a solution of the substance. If the evaporation be slow and the solution at rest, the crystals are large and well-defined. If the crystals separate by the sudden cooling of a hot solution, especially if it be agitated during the cooling, they are small. Most crystals may be divided by imaginary planes into equal, symmet- rical halves ; such planes are called planes of symmetry. Thus in the crystals in Fig. 7 the planes ab ab, ac ac, and be be are planes of symmetry. When a plane of symmetry contains two or more equivalent linear directions passing through the centre, it is called the principal plane of symmetry ; as in Fig. 8 the plane ab ab, containing the equal linear direc- tions aa and bb. Fig. S. Any normal erected upon a plane of symmetry, and prolonged in both directions until it meets opposite parts of tlie exterior of the crystal, at equal distances from the plane, is called an axis of symmetry. The axis normal to the principal plane is the principal axis. Thus in Fig. 8, aa, bb, and cc are axes of symmetry, and cc is the principal axis. 29 PHYSICAL CIIAli ACT EPS OF CHEMICAL INTEREST. Upon the relations of these imaginary planes and axes a classification of all crystalline forms into six systems has been based. I. The Cubic, Regular, or Monometric System.—The crystals of this system have three equal axes, aa, bb, cc, Fig. 7, crossing each other at right angles. The simple forms are the cube ; and its derivatives, the octahedron, tetrahedron, and rhombic dodecahedron. The crystals of this system expand equally in all directions when heated, and are not doubly refracting. II. The Right Square Prismatic, Pyramidal, Quadratic, Tetragonal, or Dimetric System contains those crystals having three axes placed at right angles to each other—two as aa and bb, Fig. 8, being equal to each other and the third, cc, either longer or shorter. The simple forms are the right square prism and the right square based octahedron. The crystals of this system expand equally only in two directions when heated ; they Fig. 9. refract light doubly in all directions except through one axis of single re- fraction. ITI. The Rhombohedral or Hexagonal System includes crystals hav- ing four axes, three of which aa, aa, aa, Fig. 9, are of equal length and cross each other at 60° in the same plane ; to which plane the fourth axis, cc, longer or shorter than the others, is at right angles. The simple forms are the regular six-sided prism, the regular dodecahedron, the rhornbohedron, and the scalenohedron. These crystals expand equally in two directions when heated, and refract light singly through the principal axis, but in other directions refract it doublv. IY. The Rhombic, Right Prismatic, or Trimetric System.—The axes of crystals of this system are three in number, all at right angles to each other, and all of unequal length. Fig. 8 represents crystals of this system, supposing aa, bb, and cc to be unequal to each other. The simple forms are the right rhombic octahedron, the right rhombic prism, the right rectangu- lar octahedron, and the right rectangular prism. The crystals of this system, like those of the two following, have no true principal plane or axis. V. The Oblique, Monosymmetric, or Monoclinic System.—The crystals of this system have three axes, two of which, aa, and cc, Fig. 10, are at 30 MANUAL OF CHEMISTRY right angles ; the third, bb, is perpendicular to one and oblique to the other ; they may be equal or all unequal in length. The simple forms are the oblique rectangular and oblique rhombic prism and octahedron. VI. The Doubly Oblique, Asymmetric, Triclinic, or Anorthic System contains crystals having three axes of unequal length, crossing each other at angles not right angles ; Fig. 10, aa, bb, and cc being unequal and the angles between them other than 90°. The crystals of the fourth, fifth, and sixth systems, when heated, ex- pand equally in the directions of their three axes ; they refract light doubly except in two axes. Secondary Forms.— The crystals occurring in nature or produced arti- ficially have some one of the forms mentioned above, or some modification Fig. 10. Fig. 11. of those forms. These modifications or secondary forms may be produced by symmetrically removing the angles or edges, or both angles and edges, of the primary forms ; thus, by progressively removing the angles of the cube, the secondary forms shown in Fig. 11 are produced. It sometimes happens in the formation of a derivative form that alter- nate faces are excessively developed, producing at length entire oblitera- tion of the others, as shown in Fig. 12. Such crystals are said to be hemihedral; they can be developed only in a system having a principal axis. Fig. 12. Isomorphism.—In many instances two or more substances crystallize in forms identical with each other, and, in most cases, such substances re- semble each other in their chemical constitution ; they are said to be PHYSICAL CHAR \CTERS OF CHEMICAL INTEREST. 31 isomorphous. This identity of crystalline form does not depend so much upon the nature of the elements themselves, as upon the structure of the molecule. The protoxide and peroxide of iron do not crystallize in the same form, nor can they be substituted for each other in reactions with- out radically altering the properties of the resultant compound. On the other hand, all that class of salts known as alums are isomorphous ; not only are their crystals identical in shape, but a crystal of one alum, placed in a saturated solution of another, grows by regular deposition of the second upon its surface. Other alums may be subsequently added to the crystal, a section of which will then exhibit the various salts, layer upon layer. Dimorphism.—Although most substances crystallize, if at all, in one simple form or in some of its modifications, a few bodies are capable of assuming two crystalline forms belonging to different systems ; such are said to be dimorphous. Thus, sulphur, as obtained by the evaporation of its solution in carbon disulphide, forms octaliedra belonging to the fourth system ; when obtained by cooling melted sulphur, the crystals are oblique prisms, belonging to the fifth system. Occasional instances of trimor- phism, of the formation of crystals belonging to three different systems by the same substance, are also known. Allotropy.—Dimorphism apart, a few substances are known to exist in more than one solid form. These varieties of the same substance ex- hibit different physical properties, while their chemical qualities are the same in kind. Such modifications are said to be allotropic. One or more allotropic modifications of a substance are usually crystalline, the other or others amorphous or vitreous. Sulphur, for example, exists not only in two dimorphous varieties of crystals, but also in a third, allotropic form, in which it is flexible, amorphous, and transparent. Carbon exists in three allotropic forms : two crystalline, the diamond and graphite ; the third amorphous. In passing from one allotropic modification to another, a substance absorbs or gives out heat. Solution.—A solid, liquid, or gas is said to dissolve, or form a solution with a liquid when the two substances unite to form a homogeneous liquid. Solution may be a purely physical process or a chemical combination. In simple or physical solution there is no modification of tne properties of the solvent and dissolved substance, beyond the liquefaction ; the latter can be regenerated in its primitive form by simple evaporation of the former ; and the act of solution is attended by a diminution of temperature. In chemical solution the properties of both solvent and dissolved are more or less modified; the dissolved substance can not be obtained from the solution by simple evaporation of the solvent, unless the compound formed be decomposable, with formation of the original substance, at the tempera- ture of the evaporation. The act of chemical solution is attended by an elevation of temperature. The amount of solid, liquid, or gas which a liquid is capable of dissolv- ing by simple solution depends upon the following conditions : 1. The nature of the solvent and substance to be dissolved.—No rule can be given which will apply in a general way to the solvent power of liquids or the solubility of substances. Water is of all liquids the best solvent of most substances ; in it some substances are so readily soluble that they absorb a sufficiency from the atmosphere to form a solution ; as calcium chloride. Such substances are said to be deliquescent. Other substances are insoluble in water in any proportion ; as barium sulphate. Elemen- 32 MANUAL OF CHEMISTRY. tary substances are insoluble, or sparingly soluble, in water. Substances rich in carbon are insoluble in water, but soluble in organic liquids. 2. The temperature lias a marked influence on the solubility of a sub- stance. As a rule, water dissolves a greater quantity of a solid substance as the temperature is increased. This increase in solubility is different in the case of different soluble substances ; thus the increase in solubility of the chlorides of barium and of potassium is directly in proportion to the increase of temperature; the solubility of sodium chloride is almost imperceptibly increased by elevation of temperature ; the solubility of sodium sulphate increases rapidly up to 33° (31°. 4 F.), above which tem- perature it again diminishes. The solubility of gases in water is the greater the lower the tempera- ture and the higher the pressure. The amount of a substance that a given quantity of solvent is capable of dissolving at a given temperature is fixed. A solution containing as much of the dissolved substance as it is capable of dissolving is said to be saturated ; if made at high temperatures it is said to be a hot saturated, and if at ordinary temperatures a cold saturated solution. If a hot saturated solution of a salt be cooled, the solid is in most in- stances separated by crystallization. If in the case of certain substances, such as sodium sulphate, however, the solution be allowed to cool while undisturbed, no crystallization occurs, and the solution at the lower tem- perature contains a greater quantity of the solid than it could dissolve at that temperature. Such a solution is said to be supersaturated. The con- tact of particles of solid material with the surface of a supersaturated so- lution induces immediate crystallization, attended with elevation of tem- perature. 3. The presence of other substances already dissolved.—If to a saturated solution of potassium nitrate, sodium chloride be added, a further quan- tity of potassium nitrate may be dissolved. In this case there is double decomposition between the two salts, and the solution contains, besides them, potassium chloride and sodium nitrate. 4. The presence of a second solvent.—If two solvents, a and b, incapable of mixing with each other, be brought in contact with a substance which both are capable of dissolving; neither a nor b take up the whole of the substance to the exclusion of the other, however greatly the solvent power or bulk of the one may exceed that of the other. The relative quantities taken up by each solvent is in a constant ratio. Diffusion of Liquids—Dialysis.—If a liquid be carefully floated upon the surface of a second liquid, of greater density, with which it is capable of mixing, two distinct layers will at first be formed. Even at perfect rest, mixture will begin immediately, and progress slowly until the two liquids have diffused into each other to form a single liquid whose density is the same throughout. Substances differ from each other in the rapidity with which they dif- fuse. Substances capable of crystallization, crystalloids, are much more diffusible than those which are incapable of crystallization—colloids. If, in place of bringing two solutions in contact with each other, they be separated by a solid or semi-solid, moist, colloid layer, diffusion takes place in the same way through the interposed layer. Advantage is taken of this fact to separate crystalloids from colloids by the process of dialysis. The mixed solutions of crystalloid and colloid are brought into the inner vessel of a dialvser, Fig. 13, whose bottom consists of a layer of moist parchment paper, while the outer vessel is filled with pure water. Water PHYSICAL CHARACTERS OF CHEMICAL INTEREST. passes into the inner vessel, and tlie crystalloid passes into the water in the outer vessel. By frequently changing the water in the outer vessels, solutions of the albuminoids or of ferric hydrate, etc., almost entirely free from crystalloids, may be obtained. Fig. 18. Specific Heat.—Equal volumes of different substances at the same temperature contain different amounts of beat. If two equal volumes of the same liquid of different temperatures be mixed together, the resulting mixture has a temperature which is the mean between the temperatures of the original volumes. If one litre of water at 4° be mixed with a litre at 38°, the resulting two litres will have a temperature of 21°. Mixtures of equal volumes of different substances, at different temperatures, do not have a temperature which is the mean of the original temperatures of its constituents. A litre of water at 4°, mixed with a litre of mercury at 38°, forms a mixture whose temperature is 27°. Mercury and water, therefor, differ from each other in their capacity for heat. The same difference exists in a more marked degree between equal weights of dissimilar bodies ; if a pound of water at 4° be agitated with a pound of mercury at 70°, both liquids will have a temperature of G7°. The amount of heat required to raise a kilo of water 1° in temperature is a definite quantity. The specific heat of any substance is the amount of heat required to raise one kilo of that substance 1° in temperature, ex- pressed in terms having the amount of heat required to raise a kilo of water 1° as unity. Spectroscopy.—Light in passing through a prism is not only re- fracted into a different course, but is also decomposed or dispersed into different colors, which make up a spectrum. A spectrum is one of three kinds:- 1.) Continuous, consisting of a continuous band of colors: red, orange, yellow, green, blue, indigo, and violet. Such spectra are pro- duced by light from white-hot solids and liquids, from gas-light, candle- light, lime-light, and electric light. 2.) Bright-line spectra, composed of bright lines upon a dark ground, are produced by glowing vapors and gases. 3.) Absorption spectra consist of continuous spectra, crossed by dark lines or bands, and are produced by light passing through a solid, liquid, or gas, capable of absorbing certain rays. Examples of bright-line and absorption spectra are shown in Fig. 14. 34 MANUAL OF CHEMISTRY. The spectrum of sun-light belongs to the third class. It is not con- tinuous, but is crossed by a great number of dark lines, known as Fraun- Red. Orange. Yellow. Green. Blue. Indigo. Violet. hofer’s lines, tlie most distinct of which are designated bv letters (No. I, Fig. 14). The spectroscope consists of four essential parts : 1st, the slit, a, Fig. 15 ; a linear opening between two accurately straight and parallel knife- Fig. 14. PHYSICAL CHARACTERS OF CHEMICAL INTEREST. 35 edges. 2d, the collimating lens, b; a biconvex lens in whose principal focus the slit is placed, and whose object it is to render the rays from the slit parallel before they enter the prism. 3d, the prism, or prisms, c, of dense glass, usually of 60°, and so placed that its refracting edge is paral- lel to the slit. 4th, an observing telescope, d, so arranged as to receive the rays as they emerge from the prisms. Besides these parts spectro- scopes are usually fitted with some arbitrary graduation, which serves to fix the location of lines observed. In direct vision spectroscopes a com- pound prism is used, so made up of prisms of different kinds of glass that the emerging ray is nearly in the same straight line as the entering ray. As the spectra produced by different substances are characterized by Fig. 15. the positions of the lines or bands, some means of fixing their location is required. The usual method consists in determining their relation to the principal Fraunhofer lines. As, however, the relative positions of these lines vary with the nature of the substance of which the prism is made, although their position with regard to the colors of the spectrum is fixed, no two of the arbitrary scales used will give the same reading. The most satisfactory method of stating the positions of lines and bands is in wave-lengths. The lengths of the waves of rays of different degrees of refrangibility have been carefully determined, the unit of measurement being the tenth-metre, of which 1010 make a metre. The wave-lengths, = A, of the principal Fraunhofer lines, are : A.... ... 7604.00 D.... ... 5892.12 G ... 4307.25 a .... .. . 7185.00 E.... ... 5269.13 H,... . .. 3968.01 B.... ... 6867.00 b .... ... 5172.00 H ... 3933.00 C.... ... 6562.01 F.... ... 4860.72 The scale of wave-lengths can easily be used with any spectroscope having an arbitrary scale, with the aid of a curve constructed by interpo- lation. To construct such a curve, paper is used which is ruled into square inches and tenths. The ordinates are marked with a scale of wave-lengths, and the abscisses with the arbitrary scale of the instrument. The posi- tion of each principal Fraunhofer line is then carefully determined in terms of the arbitrary scale, and marked upon the paper with a x at the 36 MANUAL OF CHEMISTRY. point where the line of its wave-length and that of its position in the ar- bitrary scale cross each other. Through these x a curve is then drawn as regularly as possible. In noting the position of an absorption-band, the position of its centre in the arbitrary scale is observed, and its value in wave-lengths obtained from the curve, which, of course, can only be used with the scale and prism for which it has been made. Polarimetry.—A ray of light passing from one medium into another of different density, at an angle other than 90° to the plane of separation of the two media, is deflected from its course, or refracted. Certain sub- stances have the power, not only of deflecting a ray falling upon them in certain directions, but also of dividing it into two rays, which are pecu- liarly modified. The splitting of the ray is termed double refraction, and the altered rays are said to .be polarized. When a ray of such polarized light meets a mirror held at a certain angle, or a crystal of Iceland spar peculiarly cut (a Nicholas prism), also at a certain angle, it is extinguished. The crystal which produces the polarization is called the polarizer, and that which produces the extinction the analyzer. If, when the polarizer and analyzer are so adjusted as to extinguish a ray passing through the former, certain substances are brought between them, light again passes through the analyzer ; and in order again to pro- duce extinction, the analyzer must be rotated upon the axis of the ray to the right or to the left. Substances capable of thus influencing polarized light are said to be optically active. If, to produce extinction, the analyzer is turned in the direction of the hands of a wTatcli, the substance is said to be dextrogyrous; if in the opposite direction, Icevogyrous. The distance through which the analyzer must be turned depends upon the peculiar power of the optically active substance, the length of the column interposed, the concentration if in solution, and the wave-length of the original ray of light. The specific rotary power of a substance is the rotation produced, in degrees and tenths, by one gram of the sub- stance, dissolved in one cubic centimetre of a non-active solvent, and ex- amined in a column one decimetre long. The specific rotary power is determined by dissolving a known weight of the substance in a given vol- ume of solvent, and observing the angle of rotation produced by a column of given length. Then let p = weight in grams of the substance con- tained in 1 c.c. of solution ; l the length of the column in decimetres ; a the angle of rotation observed ; and [a] the specific rotary power sought, we have a [a] = pi In most instruments monochromatic light, corresponding to the D line of the solar spectrum, is used, and the specific rotary power for that ray is expressed by the sign [a]D. The fact that the rotation is right-handed is expressed by the sign +, and that it is left-handed by the sign —. It will be seen from the above formula that, knowing the value of [a] D for any given substance, we can determine the weight of that substance in a solution by the formula a P = • [a]D x l The polarimeter or sarcliarometer is simply a peculiarly constructed polariscope used to determine the value of a. PART II. SPECIAL CHEMISTRY. CLASS I. TYPICAL ELEMENTS. Hydrogen—Oxygen. Although, in a strict sense, hydrogen is regarded by most chemists as the one and only type-element—that whose atom is the unit of atomic and molecular weights—the important part which oxygen plays in the forma- tion of those compounds whose nature forms the basis of our classification, its acid-forming power in organic compounds, and the differences existing between its properties and those of the elements of the sulphur group, with which it is usually classed, warrant us in separating it from the other elements and elevating it to the position it here occupies. HYDROGEN. Symbol = H—Univalent—Atomic iveight = 1—Molecular weight — 2— Sp. gr. — 0.06926 A*—One litre weighs 0.0896 gram •j'—100 cubic inches weigh 2.1496 grains J—1 gram measures WAS) litres f—1 grain measures 46.73 cubic inches \ —Name derived from vSwp = water, and ytmxw — I pro- duce—Discovered by Cavendish, in 1766. Occurrence.—Occurs free in volcanic gases, in fire-damp, occluded in meteorites, in the gases exhaled from the lungs, and in those of the stomach and intestine. In combination in water, hydrogen sulphide, am- moniacal compounds, and in many organic substances. Preparation.—(1.) By electrolysis of water, H is given off at the nega- tive pole. Utilized when pure H is required. * Air = 1. When the sp. gr. is referred to H = 1, A is replaced by H. f At 0° C. and 700 mm. barometric pressure. \ At 60c F. and 30 inches bar. pressure. 38 MANUAL OF CHEMISTRY. (2.) By the disassociation of water at very high temperatures. (3.) By the decomposition of water by certain metals. The alkaline metals decompose water at the ordinary temperature : Sodium. Na2 + 2H20 = 2NaH0 + H2 Water. Sodium hydrate. Hydrogen. Some other metals, such as iron and copper, effect the decomposition only at high temperatures : 3Fe2 + 8H20 = 2Fe304 -b 8H2 Iron. Water. Triferric tetroxide. Hydrogen, (4.) By decomposition of water, passed over red hot coke : C + 2H20 = C02 + 2H2 Carbon. Water. Carbon dioxide. Hydrogen. or at a higher temperature : Carbon. 2C + 2H„0 = 2C0 + 2H„ Water. Carbon monoxide. Hydrogen. (5.) By decomposition of mineral acids, in the presence of water, by zinc and certain other metals : Zn + H.H04 + xB.,0 = ZnS04 -f H2 + xB.,0 Zinc. Sulphuric acid. Water. Zinc sulphate. Hydrogen. Water. What part the water plays in the reaction is still a subject of discus- sion ; it is probable that its action is rather physical than chemical. Chemically pure zinc, or ziuc whose surface has been coated with an alloy of zinc and mercury, does not decompose the acid un- less it forms part of a gal- vanic battery whose circuit is closed. The zincs of galvanic batteries are there- for coated with the alloy mentioned — are amalga- mated— to prevent waste of zinc and acid. This method is resorted to for obtaining H ; the gas so obtained is, however, contaminated with small quantities of other gases, hydrogen phosphide, sul- phide, and arsenide. Hydrogen, carbon dioxide, hydro- gen sulphide, and other gases produced by the action of a liquid upon a solid at ordinary temperatures, are best prepared in one of the forms of apparatus snown in Figs. 16 and 17. The solid material is placed in the larger bottle (Fig. 16), or over a layer of broken glass about five centi- metres thick in the bottle A (Fig. 17). The liquid reagent is from time to time introduced by the funnel tube. Fig. 16: or the bottle B, Fig. 17, is filled with it. The wash-bottles are partially filled with water to arrest any liquid or solid impurity. The apparatus. Fig. 17, has the advantage of being always ready for use ; when the stopcock is open the gas escapes, when it is closed the internal pressure depresses the level of the liquid in A into the layer of broken glass, and the action is arrested. Fig. 16. Properties.—Physical.—Hydrogen is a colorless, odorless, tasteless gas; 14.47 times lighter than air, being the lightest substance known. The weight of a litre, 0.0896 gram, is called a crith (KpiOy = barleycorn). HYDROGEN. 39 It is almost insoluble in water and alcohol. In obedience to the law : The diffusibility of two gases varies inversely as the square roots of their densities, it is the most rapidly diffusible of gases. The rapidity with which this diffusion takes place renders the use of hydrogen, which has been kept for even a short time in gas-bags or gasometers, dangerous. At — 140° (— 229u F.), under a press- ure of 650 atmospheres, it forms a steel-blue liquid. Certain metals have the power of absorbing large quantities of hydrogen, which is then said to be occluded. Palladium ab- sorbs 376 volumes at the ordinarv temperature ; 643 vols. at*90° (194° F.), and 526 vols. at 245° (473° F.). The occluded gas is driven off by the application of heat, and possesses great chemical activity, similar to that which it has when in the nascent state. This latter quality would seem to indicate that the gas is contained in the metal, not in a mere physical state of condensation, but in chemical combination. Chemical.—Hydrogen exhibits no great tendency to combine with other elements at ordinary temperatures ; the only one with which it combines under such circumstances is chlorine, and then only under the influence of light. It does not support combustion, but, when ignited, burns with a pale blue and very hot flame ; the result of the combination being water. Mixtures of hydrogen and oxygen (in the proportion of 2H to O) explode violently on the approach of flame or by the passage of the electric spark, the explosion being caused by the sudden expansion of the vapor of water formed, under the influence of the heat of the reaction. Hydrogen also unites with oxygen when brought in contact with spongy platinum. Many compounds containing oxygen give up that element when heated in an atmosphere of hydrogen : Fig. 17. Cupric oxide. CuO + H2 = Cu + H20. Hydrogen. Copper. Water. The removal of oxygen from a compound is called a reduction or deoxi- dation. At the instant that H is liberated from its compounds it has a deoxi- dizing power similar to that, which ordinary H possesses only at elevated temperatures. The greater energy of H, and of other elements as well, in this nascent state, may be thus explained : free H exists in the form of molecules, each one of which is composed of two atoms. At the instant of its liberation from a compound, on the other hand, it is in the form of individual atoms, and that portion of force required to split up the mole- cule into atoms, necessary when free H enters into reaction, is not re- quired when the gas is in the nascent state, and consequently a less addition of force in the shape of heat is required to bring about the reaction. In its physical and chemical properties, this element more closely re- sembles those usually ranked as metals than it does those forming the class of metalloids, among which it is usually placed ; its conducting power, 40 MANUAL OF CHEMISTRY. its appearance in the liquid form, as well as its relation to the acids, which may be considered as salts of H, tend to separate it from the metalloids. Analytical Characters.—(1.) Burns with a faintly blue flame, which deposits water on a cold surface brought in contact with it; (2.) Mixed with oxygen, explodes on contact with flame, producing water. OXYGEN. Symbol = O—Bivalent—Atomic weight = 16 ; molecular weight — 32— sp. gr. — 1.10563 A (calculated = 1.1088) ; 15.95 H ; sp. gr. of liquid — 0.9787—One litre weighs 1.4300 grams — 16 crilhs—100 cubic inches weigh 34,27 grains— Name derived fromo$vs = acid, and ywdw = I produce—Dis- covered by Mayow in 1674 ; re-discovered by Priestley in 1774. Occurrence.—Oxygen is the most abundant of the elements. It exists free in atmospheric air ; in combination in a great number of substances, mineral, vegetable, and animal. Preparation.—(1.) By heating certain oxides : 2HgO = 2Hg + 02 Mercuric oxide. Mercury. Oxygen This was the method used by Priestley : 100 grams of mercuric oxide produce 5.16 litres of oxygen : 3Mn02 = Mna04 + 02 Manganese dioxide. Trimanganic tetroxide. Oxygen. The black oxide of manganese is heated to redness in an iron or clay retort (Scheele, 1775) ; and 100 grams yield 8.51 litres of oxygen. (2.) By the electrolysis of water, acidulated with sulphuric acid, O is given off at the positive pole. (3.) By the action of sulphuric acid upon certain compounds rich in O : manganese dioxide, potassium dicliromate, and plumbic peroxide : Manganese dioxide. 2Mn02 + 2HsS04 = 2MnS04 + 2H20 + 02 Sulpliuric acid. Manganous sulphate. Water. Oxj'gen. 100 grams of manganese dioxide produce 12.82 litres of O. (4.) By decomposing H.,S04 at a red heat, 2H2S04 = 2SO,, 4-2H20 + O... (5.) By the decomposition by heat of certain salts rich in O : alkaline permanganates, nitrates, and chlorates. The best method, and that usually adopted, is by heating a mixture of potassium chlorate and manganese dioxide in equal parts, moderately at first and more strongly toward the end of the reaction. At the end of the operation the manganese dioxide remains, apparently unaltered, and it is probable that during the action it goes through a series of oscillating oxi- dations and deoxidations, which take place at a lower temperature than that required for the decomposition of the chlorate alone. The chlorate gives up all its O (27.2G litres from 100 grains of the salt), according to the equation : Potassium chlorate. 2KC103 = 2KC1 + 302 Potassium chloride. Oxygen. OXYGEN. 41 The operation may be conducted in the apparatus shown in Fig. 18, or, on a large scale, with a copper or iron retort. Pkopekties.—Physical.—Oxygen is a colorless, odorless, tasteless gas, very sparingly soluble in water, somewhat more soluble in absolute alco- hol. it liquefies at — 140° (229" F.) under a pressure of 300 atmospheres. Chemical.—Oxygen is characterized, chemically, by the strong ten- dency which it exhibits to enter into combination with other elements, only one of which is known, i.e., fluorine, that does not form an oxygenated compound. With most elements it unites directly, especially at elevated temperatures. In many instances this union is attended by the appear- ance of light, and always by the extrication of heat. The luminous union of O with another element constitutes the familiar phenomenon of combus- tion, and is the principal source from which we obtain so-called artificial Fio. 18. lieat and light. A body is said to be combustible when it is capable of so energetically combining with the oxygen of the air as to liberate light as well as heat. Gases are said to be supporters of combustion, when com- bustible substances will unite with them, or with some of their constitu- ents, the union being attended with the appearance of heat and light. The distinction between combustible substances and supporters of com- bustion is, however, one of mere convenience ; the action taking place be- tween the two substances, one is as much a party to it as the other. A jet of air burns in an atmosphere of coal-gas as readily as a jet of coal-gas burns in air. The compounds of oxygen—the oxides—are divisible into three groups: 1. Anhydrides—oxides capable of combining with water to form acids. Thus sulphuric anhydride, S03, unites with water to form sulphuric acid, h3so4. The term “ anhydride ” is not limited in application to binary com- pounds, but applies to any substance capable of combining with water to form an acid. Thus the compound C4H1.03 is known as acetic anhydride, 42 MANUAL OF CHEMISTRY. because it combines with water to form acetic acid : C4HB03 + H.,0 =• 2C3H402. (See compounds of arsenic and sulphur, p. 88.) 2. Basic oxides are such as combine with water to form bases. Thus, calcium oxide, CaO, unites with water to form calcium hydrate, CaH„0„. 3. Saline, neutral, or indifferent oxides are such as are neither acid nor basic in character. In some instances they are essentially neutral, as in the case of the protoxide of hydrogen or water. In other cases they are formed by the union of two other oxides, one basic, the other acid in qual- ity, such as the red oxide of lead, Pb30„ formed by the union of a mole- cule of the acidulous peroxide, Pb03, with two of the basic protoxide, PbO. It is to oxides of this character that the term “ saline ” properly applies. The process of respiration is very similar to combustion, and as oxygen gas is the best supporter of combustion, so, in the diluted form in which it exists in atmospheric air, it is not only the best, but the only supporter of animal respiration. (See carbon dioxide.) Analytical Characters.—1.) A glowing match-stick bursts into flame in free oxygen. 2.) Free O when mixed with nitrogen dioxide produces a brown gas. OZONE.—ALLOTROPIC OXYGEN. Air through which discharges of static electricity have been passed, and oxygen obtained by decomposition of water (if electrodes of gold or platinum be used), have a peculiar odor, somewhat resembling that of sul- phur, which is due to the conversion of a part of the oxygen into ozone. Ozone has not been obtained free from oxygen ; indeed, the highest degree of concentration which has been reached does not exceed ten per cent, of ozone. Thus diluted, ozone is produced : 1.) By the decomposi- tion of water by the battery. 2.) By the slow oxidation of phosphorus in damp air. 3.) By the action of concentrated sulphuric acid upon barium dioxide. 4.) By the passage of silent electric discharges through air or oxygen. In the preparation of ozonized oxygen the best results are obtained by passing a slow current of oxygen through an apparatus made entirely of glass and platinum, cooled by a current of cold water, and traversed by the invisible discharge of an induction coil. Under the most favorable conditions hitherto attained, the nearest ap- proach to pure ozone has been ten parts in one hundred, the remainder being unaltered oxygen. When oxygen is ozonized it contracts slightly in volume, and when the ozone is removed from ozonized oxygen by mercury or potassium iodide the volume of the gas is not diminished. These facts, and the great chem- ical activity of ozone, have led chemists to regard it as condensed oxygen ; the molecule of ozone being represented thus (OOO), while that of ordi- nary oxygen is (00). Ozone is very sparingly soluble in water, insoluble in solutions of acids and alkalies. In the presence of moisture it is slowly converted into oxy- gen at 100° (212° F.), a change which takes place rapidly and completely at 237° (459° F.). It is a powerful oxidant; it decomposes solutions of potassium iodide with formation of potassium hydrate and liberation of iodine ; it oxidizes all metals except gold and platinum, in the presence of moisture ; it decolorizes indigo and other organic pigments, and acts rapidly upon rubber, cork, and other organic substances. WATER. 43 Analytical Characters.—1.) Neutral litmus paper, impregnated with solution of potassium iodide, is turned blue when exposed to air contain- ing ozone. The same litmus paper without iodide is not affected. 2.) Manganous sulphate solution is turned brown by ozone. 3.) Solutions of thallous salts are colored yellow or brown by ozone. When inhaled, air containing 0.07 gram of ozone per litre causes in- tense coryza and haemoptysis. It is probable that ozone is by no means as constant a constituent of the atmosphere as was formerly supposed. (See Hydrogen dioxide.) Compounds of Hydrogen and Oxygen. Two are known—hydrogen oxide or water, H.,0; hydrogen peroxide or oxygenated water, HO,. Water, H..O—Molecular weight — 18—Sp. gr. = 1—Vapor density = 0.6218 A —Composition discovered by Priestley in 1780. Occurrence.—In unorganized nature H.,0 exists in the gaseous form in atmospheric air and in volcanic gases; in the liquid form very abundantly; and as a solid in snow, ice, and hail. As water of crystallization it exists in definite proportion in certain crystals, to the maintenance of whose shape it is necessary. In the organized world H.,0 forms a constituent part of every tissue and fluid. Formation.—Water is formed: 1. By union, brought about by eleva- tion of temperature, of one vol. O with two vols. H. 2. By burning H or substances containing it in air or O. 3. By heating organic substances containing H to redness with cupric oxide, or with other substances capable of yielding O. This method of formation is utilized to determine the amount of H contained in organic substances. 4. When an acid and a hydrate react upon each other to form a salt : Sulphuric acid. H3S04 + 2KHO = K3S04 + 2H30 Potassium hydrate. Potassium sulphate. Water. 5. When a metallic oxide is reduced by hydrogen : CuO + H3 = Cu + H„0 Cupric oxide. Hydrogen. Copper. Water. 6. In the reduction and oxidation of many organic substances. Pure H.,0 is not found in nature. When required pure it is separated from suspended matters by filtration, and from dissolved substances by distillation. Properties.—Physical.—With a barometric pressure of 760 mm. H„0 is solid below 0° (32J F.) ; liquid between 0° (32° F.) and 100° (212° F.); and gaseous above 100° (212° F.). When HO is enclosed in capillary tubes, or is at complete rest, it may be cooled to —15° (5° F.) without solidifying. If at this temperature it be agitated, it solidities instantly and the temperature suddenly rises to 0° (32 F.). The melting-point of ice is lowered 0.0075° (0.0135° F.) for each additional atmosphere of pressure. 44 MANUAL OF CHEMISTRY. The boiling-point is subject to greater variations than the freezing- point. It is the lower as the pressure is diminished, and the higher as it is increased. Advantage is taken of the reduced boiling-point of solutions in vacuo for the separation of substances, such as cane sugar, which are injured at the temperature of boiling H,0. On the other hand, the in- creased temperature that may be imparted to liquid H O under pressure is utilized in many processes, in the laboratory and in the arts, for effecting solutions and chemical actions which do not take place at lower tempera- tures. The boiling-point of H.,0 holding solid matter in solution is higher than that of pure the degree of increase depending upon the amount and nature of the substance dissolved. On the other hand, mixtures of H.,0 with liquids of lower boiling-point boil at temperatures less than 100° (212° F.). Although the conversion of water into water-gas takes place most actively at 100° (212° F.), water and ice evaporate at all tempera- tures. Water is the best solvent we have, and acts in some instances as a sim- ple solvent, in others as a chemical solvent. When a solid absorbs sufficient water from the air to form a solution it is said to deliquesce. Gases are more soluble in cold than in hot liquids. Hydrogen forms an exception to this rule, being equally soluble in all temperatures. The solubility of a gas in water varies directly as the pressure. In most cases solids are more soluble in hot than in cold liquids. When a liquid contains as much of a dissolved substance as it is capable of holding at the existing temperature, it is said to be saturated. Solutions of certain salts, saturated at high temperatures, may be cooled without depositing any of the salt; they are then super-saturated, and contain more of the dissolved substance than they could take up at the lower temperature. A saturated solution of one substance in H.,0 is often capable of dis- solving considerable quantities of another substance, and of then becom- ing capable of taking up a further quantity of the first substance. The power of H,,0 to dissolve gases increases with increased pressure. Fats, resins, and, in general, organic substances containing a large number of carbon atoms, are insoluble in H.,0. Vapor of water is colorless, transparent, and invisible. Sp. gr. 0.6234, A or 9 H. A litre of vapor of water weighs 0.8064. The latent heat of vaporization of water is 536.5 ; that is, as much heat is required to vapor- ize 1 kilo, of water at 100° as would suffice to raise 536.5 kilos, of water 1° in temperature. In passing from the liquid to the gaseous state, water expands 1,696 times in volume. Chemical.—Water may be shown to consist of 1 voL O and 2 vols. H, or 8 by weight of O and 1 by weight of H, either by analysis or synthesis. Analysis is the reducing of a compound to its constituent elements. Synthesis is the formation of a compound from its elements. A partial synthesis is one in which a complex compound is produced from a simpler one, but not from the elements. Water may be resolved into its constituent gases : 1st. By electrolysis of acidulated water ; H being given off at the negative and O at the posi- tive pole. 2d. By passing vapor of H„0 through a platinum tube heated to a whiteness, or through a porcelain tube heated to about 1,100°. 3d. By the action of the alkaline metals. Hydrogen is given off, and the me- tallic hydrate remains in solution in an excess of H.,0, 4th. By passing vapor of H O over red-hot iron. Oxide of iron remains and H is given off. WATER. 45 Water combines with oxides to form new compounds, some of which are acids and others bases, known as hydrates. A hydrate is a compound formed by the replacement of part of the hydro- gen of water by another element or radical. The hydrates of the electro-negative elements and radicals are acids ; most of those of the electro-positive elements and radicals are basic hydrates. A compound capable of combining with water to form an acid is called an anhydride. Certain substances, in assuming the crystalline form, combine with a definite proportion of water, which is known as water of crystallization, and whose presence, although necessary to the maintenance of certain physical characters, such as color and crystalline form, does not modify their chem- ical reactions. In many instances a portion of the water of crystallization may be driven off at a comparatively low temperature, while a much higher temperature is required to expel the remainder. This latter is known as water of constit ution. The symbol Aq (Latin, aqua) is frequently used to designate the -water of crystallization, the water of constitution being indicated bv H,0. Thus MgS04 H .O -f- G Aq represents magnesium sulphate with one molecule of water of constitution and six molecules of water of crystallization. We consider it preferable, however, as the distinction between water of crys- tallization and water of constitution is only one of degree and not of kind, to use the symbol Aq to designate the sum of the two ; thus, MgSO + 7 Aq. Crystals which lose their water of crystallization on exposure to air are said to effloresce ; those which do not are said to be permanent Water decomposes the chlorides of the second class of elements (those of carbon only at high temperatures and under pressure); while the chlorides of the elements of the third and fourth classes are either insolu- ble, or soluble -without decomposition. Natural Waters.—Water, as it occurs in nature, always contains solid and gaseous matter in solution, and frequently solids in suspension. Natural waters may be classified, according to the nature and quantity of foreign matters which they contain, into potable and unpotable waters. To the first class belong rain-water, snow- and ice-water, spring-water (fresh), river-water, lake-water, and well-water. To the second class belong stagnant waters, sea-water, and the waters of mineral springs. Rain-water is usually the purest of natural waters, so far as dissolved solids are concerned, containing very small quantities of the chlorides, sulphates, and nitrates of sodium and ammonium. Owing to the large surface exposed during condensation, rain-water contains relatively large quantities of dissolved gases—oxygen, nitrogen, and carbon dioxide ; and sometimes hydrogen sulphide and sulphur dioxide. The absence of car- bonates and the presence of nitrates and oxygen render rain-water particu- larly prone to dissolve lead when in contact with that metal. In summer, rain-water is liable to become charged with vegetable organic matter sus- pended in the atmosphere. Ice-water contains very small quantities of dissolved solids or gases, which, during freezing, remain in great part in the unfrozen water. Sus- pended impurities are imprisoned in the ice and liberated when this is melted. Melted snow contains about the same proportion of fixed solid matter as rain-water, but a less proportion of ammoniacal salts and of gases. Spring-water is rain-water which, having percolated through a portion 46 MANUAL OF CHEMISTRY. of the earth’s crust (in which it may also have been subjected to pressure), has become charged with solid and gaseous matter ; varying in kind and quantity according to the nature of the strata through which it has perco- lated, the duration of contact, and the pressure to which it was subject during such contact. Spring-waters from igneous rocks and from the older sedimentary for- mations are fresh and sweet, and any spring-water may be considered such whose temperature is less than 20" (68° F.), and which does not contain more than 0.4 gram of solid matter to the litre (28 grains per gal.) ; pro- vided that a large proportion of the solid matter does not consist of salts having a medicinal action, and that sulphurous gases and sulphides are absent. Artesian wells are artificial springs, produced by boring in a low-lying district, until a pervious layer between two impervious strata is reached ; the outcrop of the system being in an adjacent elevated region. lliver-water is a mixture of rain-water, spring-water, and the drainage water of the district through which the river flows, to which snow-water, ice-water, or sea-water is sometimes added. The water of a river flowing rapidly through a granitic region is, unless polluted by man, bright, fresh, and highly aerated ; that of a stream flowing sluggishly through rich al- luvial land is unaerated, and rich in dissolved and suspended solids. The amount of dissolved solids in river water increases with the dis- tance from its source. The chief sources of pollution of river-water are by the discharge into them of the sewage of towns and cities, or of the waste products of factories. Lake-water is an accumulation of river- and rain-water. As the waters of lakes are kept in constant agitation both bv the wind and by the cur- rent, they become to a great extent purified from organic contamina- tion. Well-water may be very good or very bad. If the well be simply a res- ervoir dug over a spring, and removed from sources of contamination, it has all the characters of fresh spring-water. If, on the other hand, it be simply a hole dug in the earth, the water which it contains is the surface ■water which has*percolated through the thin layer of earth corresponding to the depth of the well, and is consequently warm, unaerated and charged with organic impurity. Wells dug near dwellings are very liable to become charged with the worst of contaminations, animal excreta, by their filtration through the soil, either by reason of the fracture of the house-drain or otherwise. Impurities in Potable Waters.—A water to be fit for drinking pur- poses should be cool, limpid, and odorless. It should have an agreeable taste, neither flat, salty, nor sweetish, and it should dissolve soap readily, without formation of any flocculent precipitate. Although it is safe to condemn a water which does not possess the above characters, it is by no means safe to regard all waters which do pos- sess them as beyond suspicion. To determine whether a water is potable it must be more carefully examined as to the following constituents : Total solids.—The amount of solid material dissolved in potable waters varies from 5 to 40 in 100,000 ; and a water containing more than the latter quantity (28 grains per gall.) is to be condemned on that account alone. To determine t'ne quantity of total solids 25 c.c. of the filtered water are evaporated to dryness in a pre- viously weighed platinum dish, over the water-bath. The dish with the contained dry residue is cooled in a desiccator and again weighed. The increase in weight, multiplied by 4,000, gives the total solids in parts per 100,000. WATER. 47 Hardness.—The greater part of the solid matter dissolved in natural waters consists of the salts of calcium, accompanied by less quantities of. the salts of magnesium. The calcium salt is usually the carbonate or the sulphate ; sometimes the chloride, phosphate, or nitrate. A water containing an excess of calcareous salt is said to be hard, and one not so charged is said to be soft. If the hardness be due to the pres- ence of the carbonate it is temporary, if due to the sulphate it is perma- nent. Calcium carbonate is almost insoluble in pure water, but in the presence of free carbonic acid the more soluble bicarbonate is dissolved, but on the water being boiled, it is decomposed with precipitation of the carbonate if the quantity exceed 0.5 gram per litre. As calcium sulphate is held in solution by virtue of its own, albeit sparing, solubility, it is not deposited when the water is boiled. An accurate determination of the quantity of calcium and magnesium salts in water is rarely required ; it is, however, frequently desirable to de- termine their quantity approximately, the result being the degree of hardness. For this purpose a solution of soap of known strength is required. This is made by dissolving 10 grams of air-dried, white Castile soap, cut into thin shavings, in a litre of dilute alcohol (sp. gr. 0.949). To determine whether this solution contains the proper amount of soap, 10 c.c. of a solution, made by dissolving 1.11 grams of pure, recently fused calcium chloride in a litre of water, are diluted with 00 c.c. of water and the soap solution added until a persistent lather is produced on agitation. If 11 c.c. of soap solution have been used it has the proper strength ; if a greater or less quantity have been added it must be concentrated or diluted in proportion to the excess or deficiency. The soap solution must not be filtered, but, if turbid, must be shaken before using. To determine the hardness, 70 c.c. of the water to be tested are placed in a glass-stoppered bottle of 250 c.c. capacity, and the soap solution gradually added from a burette. After each addition of soap solu- tion the bottle is shaken, and allowed to lie upon its side five minutes. This is continued until at the end of five minutes a lather remains upon the surface of the liquid in the bottle. At this time the hardness is in- dicated by the number of c.c. of soap solution added, minus one. If more than 16 c.c. of soap solution are added the liquid in the bottle must be diluted with 70 c.c. of distilled water. A good drinking-water should not have a hardness of more than fifteen. Chlorides. —The presence of the chlorides of the alkaline metals, in quantities not sufficient to be detectable by the taste, is of no importance per se ; but in connection with the presence of organic impurity, a deter- mination of the amount of chlorine affords a ready method of indicating the probable source of the organic contamination. As vegetable organic matter brings with it but small quantities of chlorides, while animal contaminations are rich in those compounds, the presence of a large amount of chlorine serves to indicate that organic impurity is of animal origin. Indeed, when time presses, as during an epidemic, it is best to rely upon determinations of chlorine, and condemn all waters containing more than 1.5 in 100,000 (one grain per gallon) of that element. For the determination of chlorine two solutions are required : a solution of silver nitrate containing 4.79 grams per litre ; a strong solution of potassium chromate. One hundred c.c. of the water are placed in a beaker with enough of the chromate solution to communicate a distinct yellow color. If the reaction be acid it is rendered neutral or faintlu alkaline by the addition of sodium carbonate solution. The silver solu- tion is now allowed to flow in from a burette, drop by drop, during constant agitation, until a faint, reddish tinge persists. At this time the burette reading is taken ; each c.c. of silver solution added represents O.Ul of chlorine per litre. Organic Matter.—The most serious of the probable contaminations of drinking-water is that by organic matters containing nitrogen. When these are present in even moderate quantity, and when, at the same time, the proportion of chlorine is greater than usual, the water has been con- taminated by animal excreta and contains, under suitable conditions, the causes of disease, be they germs or poisons. Of the methods suggested for the determination of the amount of or- ganic matter in natural waters there is unfortunately none which is easy 48 MANUAL OF CHEMISTRY. of application and at the same time reliable. That which yieids the best results is Wanklyn’s process : The following solutions are required; a. Made by dissolving 200 grams of potassium hydrate and 8 grams of potassium permanganate in a litre of water. The solution is boiled down to about 125 c.c., cooled, and brought to its original bulk by the addition of boiled distilled water, b. Kessler's reagent. £6 grams of potassium iodide and 13 grams of mercuric chloride are dissolved in 800 c.c. of water by the aid of heat and agitation. A cold, saturated solution of mercuric chloride is then added, drop by drop, until the red pre- cipitate which is formed is no longer redissolved on agitation; 100 grams of potassium hydrate are then dis- solved in the liquid, to which a slight excess of mercuric chloride solution is finally added, and the bulk of the whole made up to a litre with water. The solution is allowed to stand, decanted, and preserved in com- pletely filled, well-stoppered bottles, c. Standard solutions of ammonia. The stronger of these is made by dissolving 3.15 grams of ammonium chloride in a litre of water. The weaker, by mixing one volume of the stronger with 99 volumes of water. The latter contains 0.00001 gram of ammonia in each c.c., and is the one used in the determinations, the stronger solution serving only for its convenient preparation, d. A saturated solution of sodium carbonate, e. Distilled water. The middle third of the distillate, 100 c.c. of which must not be perceptibly colored in ten minutes by the addition of 2 c.c. of Nessler’s reagent. The testing of a water is conducted as follows : Half a litre of the water to be tested (before taking the sample, the demijohn or other vessel containing the water must be thoroughly shaken) is introduced, by a funnel, into a tubulated retort capable of holding one litre. If the water be acid, 10 c.c. of the solution of sodium carbonate d are added. Having connected the retort with a Liebig’s condenser, the joint being made tight by a packing of moistened filter-paper, the water is made to boil as soon as possible by applying the flame of a Bunsen burner brought close to the bottom of the naked retort. The first 50 c.c. of distiilate are collected in a cylindrical vessel of clear glass, about an inch in diameter. The following 150 c.c. are collected and thrown away, after which the fire is withdrawn. While these are passing over, the first 50 c.c. are Nesslerized (vide infra), and the result, plus one-third as much again, is the amount of free am- monia contained in the half-lit re of water. When 200 c.c. have distilled over, all the free ammonia has been removed, and it now remains to decom- pose the organic material, and determine the amount of ammonia formed. To effect this, 50 c.c. of the permanganate solution a are added through the funnel to the contents of the retort, which is shaken, stop- pered, and again heated. The distillate is now collected in separate portions of 50 c.c. each, in glass cylin- ders, until 3 such portions have been collected. These are then separately Nesslerized as follows: 2 c.c. of the Nessler reagent are added to the sample of 50 c.c. of distillate: if ammonia be present, a yellow or brown color will be produced, dark in proportion to the quantity of ammonia present. Into another cylin- der a given quantity of the standard solution of ammonia c is allowed to flow from a burette ; enough water is added to make the bulk up to 50 c.c., and then 2 c.c. of Nessler reagent. This cylinder, and that con- taining the 50 c.c. of Nesslerized distillate, are then placed side by side upon a sheet of white paper and their color examined. If the shade of color in the two cylinders be exactly the same, the 50 c.c. of distillate contain the same amount of ammonia as the quantity of standard solution of ammonia used. If the colors be different in intensity, another comparison-cylinder must be arranged, using more or less of the standard solution, as the first comparison-cylinder was lighter or darker than the distillate. When the proper simi- larity of shades has been attained, the number of cubic centimetres of the standard solution used is deter- mined by the reading on the burette. This process, which, with a little practice, is neither difficult nor tedious, is to be repeated with the first 50 c.c. of distillate and with the three portions of 50 c.c. each, dis- tilled after the addition of the permanganate solution. If, for example, it required 1 c.c. of standard solu- tion in Nesslerizing the first 50 c.c., and for the others 3.5 c.'\, 1.5 c.c., and 0.2 c.c., the following is the re- sult and the usual method of recording it: Free ammonia 01 Correction 003 .013 Free ammonia per litre 020 milligr. Albuminoid ammonia 035 .015 .002 .052 Albuminoid ammonia per litre 104 milligr. If a water yield no albuminoid ammonia it is organically pure, even if it contains much free ammonia and chlorides ; if it contains from .02 to .05 milligrams per litre, it is still quite pure; when the albuminoid ammonia reaches 0.1 milligr. per litre the water is to he looked upon with suspi- cion ; and it is to be condemned when the proportion reaches 0.15. When free ammonia is also present in considerable quantity, a water yielding 0.05 of albuminoid ammonia is to be looked upon with suspicion. Poisonous Metals.—Those most liable to occur in drinking waters are iron, copper, and lead, and of these the last is the most important. The power possessed by a water of dissolving lead varies materially with the nature of the substances which it holds in solution. The pres- ence of nitrates is favorable to the solution of lead, an influence which is, however, much diminished by the simultaneous presence of other salts. A water highly charged with oxygen dissolves lead readily, especially if the metallic surface be so exposed to the action of the water as to be alter- nately acted upon by it and by the air. On the other hand, waters con- taining carbonates or free carbonic acid may be left in contact with lead with comparative impunity, owing to the formation of a protective coating WATER. 49 of the insoluble carbonate of lead on the surface of the metal. This does not apply, however, to water charged with a large excess of carbon dioxide under pressure. Of all natural waters that most liable to contamination with lead is rain-water ; it contains ammonium nitrate with very small quantities of other salts ; and it is highly aerated, but contains no car- bonates and comparatively small quantities of carbon dioxide. Obviously, therefor, rain-water should neither be collected from a leaden roof, nor stored in leaden tanks, nor drank after having been long in contact with lead pipes. As a rule, the purer the water the more liable it is to dissolve lead when brought in contact with that metal, especially if the contact occur when the water is at a high temperatux-e, or when it lasts for a long period. To determine the power of water for dissolving lead, take two tumblers of the water to be tested ; in one place a piece of lead, whose surface has been scraped bright, and allow them to stand twenty-four hours. At the end of that time remove the lead and pass sulphuretted hydrogen through the water in both tumblers ; if the one which contained the metal become perceptibly darker than the other, the water has a power of dis- solving lead such as to render its contact with surfaces of that metal dan- gerous if prolonged beyond a short time. To test for the presence of poisonous metals, solution of ammonium sulphydrate is added to the water contained in a porcelain capsule. If a dark color be produced, which is not discharged on addition of hydro- chloric acid, the water is contaminated with lead or copper. For quantitative determinations solutions containing known quantities of the poisonous metals are used: for iron grams of ferrous sulphate in a litre of water; for copper 3.93 grams of cupric sulphate to the litre ; and for lead 1.96 gram of lead acetate to the litre. One c.c. of each solution contains 0.001 gram of the metal. To use the solutions 100 c.c. of the water to be tested and 100 c.c. of pure water are placed in two porcelain capsules, to each of which some ammonium sulphydrare is then added. The appropriate stand- ard solution is then allowed to flow into the capsule containing the pure water, until the shade of color produced is the same as that of the liquid in the other capsule. The burette reading at this time gives the number of centigrams of the metal in a litre of water. Suspended solids.—Most natural waters deposit, on standing, more or less solid, insoluble material. These substances have been either sus- pended mechanically in the water, which deposits them when it remains at rest, or they have been in solution, and are deposited by becoming in- soluble as the water is deprived of carbon dioxide by exposure to air and by relief from pressure. The suspended particles should be collected by subsidence in a conical glass, and should be examined microscopically for low forms of animal and vegetable life. The quantity of suspended solids is determined by passing a litre of the turbid water through a dried and weighed filter, which with the collected deposit, is again dried and weighed. The difference between the two weights is the weight of suspended matter in a litre of the water. Purification of water.—The artificial means of rendering a more or less contaminated water fit for use are of five kinds : 1. Distillation ; 2. Subsi- dence ; 3. Filtration ; 4. Precipitation ; 5. Boiling. The method of distillation is used in the laboratory when a very pure water is desired, and also at sea upon steamships, and even on sailing ves- sels upon occasion. Distilled water is, however, too pure for continued use, being hard of digestion, and flat to the taste from the absence of gases and of solid matter in solution. When circumstances oblige the use of such water, it should be agitated with air, and should be charged with inorganic matter to the extent of about 0.03 gram each of calcic bicarbon- ate and sodium chloride to the litre. Purification by subsidence is adopted only as an adjunct to precipitation and filtration, and for the separation of the heavier parti despf suspended matter. 50 MANUAL OF CHEMISTRY. The ideal process of filtration consists in the separation of all particles of suspended matter, without any alteration of such substances as are held in solution. In the filtration of potable waters on a large scale, however, the more minute particles of suspended matters are only partially sepa- rated, while, on the other hand, an important change in the dissolved materials takes place, at least in certain kinds of filters, in the oxidation of organic matters, whether in solution or in suspension. In the filtration of large quantities of water it is passed through sand or charcoal, or through both substances arranged in alternate layers. Filtration through charcoal is much more effective than that through sand, owing to the much greater activity of the oxidation of nitrogenized organic matter in the former case. Precipitation processes are only adapted to hard waters, and are de- signed to separate the excess of calcium salt, and at the san\e time a con- siderable quantity of organic matter, which is mechanically carried down with the precipitate. The method usually followed consists in the addi- tion of lime (in the form of lime-water), in just sufficient quantity to neutralize the excess of carbon dioxide present in the water. The added lime, together with the calcium salt naturally present in the water, is then precipitated, except that small portion of calcium carbonate which the water, freed from carbon dioxide, is capable of dissolving. To determine when sufficient lime-water has been added, take a sample from time to time during the addition, and test it with solution of silver nitrate until a brown precijiitate is formed. At this point cease the addition of lime- water and mix the limed water with further portions of the hard water, until a sample, treated with silver-nitrate solution, gives a yellowish in place of a brown color. The purification of water by boiling can only be carried on upon a small scale ; it is, however, of great value for the softening of temporarily hard waters, and for the destruction of organized impurities, for which latter purpose it should never be neglected during outbreaks of cholera and typhoid, if, indeed, water be drank at all at such times. Mineral Waters.—Under this head are classed all waters which are of therapeutic or industrial value, by reason of the quantity or nature of the dissolved solids which they contain ; or which have a temperature greater than 20° (G8° Fall.). The composition of mineral waters varies greatly, according to the na- ture of the strata or veins through which the water passes, and to the conditions of pressure and previous composition under which it is in con- tact with these deposits. The substances almost universally present in mineral waters are : oxy- gen, nitrogen, carbon dioxide ; sodium carbonate, bicarbonate, sulphate and chloride ; calcium carbonate and bicarbonate. Of substances occasion- ally present the most important are : sulphydric acid ; sulphides of sodium, iron and magnesium ; bromides and iodides of sodium and magnesium ; calcium and magnesium chlorides ; carbonate, bicarbonate, sulphate, per- oxide, and crenate of iron ; silicates of sodium, calcium, magnesium, and iron ; aluminium salts ; salts of lithium, caesium, and rubidium ; free sul- phuric, silicic, arsenic, and boric acids ; and ammoniacal salts. Although a sharply defined classification of mineral waters is not pos- sible, one which is useful, if not accurate, may be made, based upon the predominance of some constituent, or constituents, which impart to the water a well-defined therapeutic value. A classification which has been generally adopted is into five classes : I. Acidulous waters ; whose value depends upon dissolved carbonic acid. WATER. 51 They contain but small quantities of solids, principally the bicarbonates of sodium and calcium and sodium chloride. II. Alkaline waters ; which contain notable quantities of the carbonates or bicarbonates of sodium, potassium, lithium, and calcium, sufficient to communicate to them an alkaline reaction, and frequently a soapy taste ; either naturally or after expulsion of carbon dioxide by boiling. III. Chalybeate waters ; which contain salts of iron in greater propor- tion than 40 milligrams per litre (2.8 grains per gall.). They contain fer- rous bicarbonate, sulphate, crenate, and apocrenate, calcium carbonate, sulphates of potassium, sodium, calcium, magnesium, and aluminium, notable quantities of sodium chloride, and frequently small amounts of ar- senic. They have the taste of iron and are usually clear as they emerge from the earth. Those containing ferrous bicarbonate deposit a sediment on standing, by loss of carbon dioxide and formation of ferrous carbonate. IV. Saline waters ; which contain neutral salts in considerable quantity. The nature of the salts which they contain is so diverse that the group mav well be subdivided : a. Chlorine waters ; which contain large quantities of sodium chloride, accompanied by less amounts of the chlorides of potassium, calcium, and magnesium. Some are so rich in sodium chloride that they are not of service as therapeutic agents, but are evaporated to yield a more or less pure salt. Any natural water containing more than 3 grams per litre (210 grains per gall.) of sodium chloride belongs to this class, provided it do not contain substances more active in their medicinal action in such pro- portion as to warrant its classification elsewhere. Waters containing more than 15 grams per litre (1,050 grains per gall.) are too concentrated for internal administration. ft. Sulphate waters are actively purgative from tlie presence of consider- able proportions of the sulphates of sodium, calcium, and magnesium. Some contain large quantities of sodium sulphate, with mere traces of the calcium and magnesium salts, while in others the proportion of the sul- phates of magnesium and calcium is as high as 30 grams per litre (2,100 grains per gall.), to 20 grams per litre (1,400 grains per gall.) of sodium sulphate. They vary much in concentration ; from 5 grams (350 grains per gall.) of total solids to the litre in some, to near GO grams per litre (4,200 grains per gall.) in others. They have a salty, bitter taste, and vary much in temperature. Y Bromine and iodine waters are such as contain the bromides or iodides of potassium, sodium, or magnesium in sufficient quantity to com- municate to them the medicinal properties of those salts. Y. Sulphurous waters ; which hold hydrogen sulphide or metallic sul- phides in solution. They have a disagreeable odor and are usually wrarm. They contain 0.2 to 4 grams of solids per litre (14-280 grains per gall.). Physiological. —Water is taken into the body both as a liquid and as a constituent of every article of food ; the amount ingested by a healthy adult being 2 25 to 2.75 litres to 3 quarts) per diem. The greater the elimination and the drier the nature of the food the greater is the amount of H,0 taken in the liquid form. Water is a constituent of every tissue and fluid of the body, varying from 0.2 per cent, in the enamel of the teeth to 99.5 per cent, in the per- spiration and saliva. It constitutes about 60 per cent, of the weight of the body. The consistency of the various parts does not depend entirely upon the relative proportion of solids and H20, but is influenced by the nature of 52 MANUAL OF CHEMISTRY. the solids. The blood, although liquid in the ordinary sense of the term, contains a less proportional amount of H„0 than does the tissue of the kidneys, and about the same proportion as the tissue of the heart. Although the bile and mucus are not as fluid as the blood, they contain a larger proportion of H,0 to solids than does that liquid. Water is discharged by the kidneys, intestine, skin, and pulmonary surfaces. The quantity discharged is greater than that ingested ; the excess being formed in the body by the oxidation of the H of its organic constituents. Hydrogen Dioxide. Hydrogen peroxide—Oxygenated water H O,—Molecular weight = 34—Sp. gr. — 1.455—Discovered by Then- ard in 1818. This substance may be obtained in a state of purity by accurately fol- lowing the process of Thenard. It may also be obtained, mixed with a large quantity of H.,0, by passing a rapid current of carbon dioxide through H20 holding hydrate of barium dioxide in suspension —BaO,H„ + C02 = BaC03 + H200. It is also formed in small quantity during the slow oxidation of many elements and compounds, such as P, Pb, Zn, Cd, Al, alcohol, ether, and the essences. The pure substance is a colorless, syrupy liquid, which, when poured into 11,0, sinks under it before mixing. It has a disagreeable, metallic taste, somewhat resembling that of tartar emetic. When taken into the mouth it produces a tingling sensation, increases the flow of saliva, and bleaches the tissues with which it comes in contact. It is still liquid at — 30° (— 22° F.). It is very unstable, and, even in darkness and at ordinary temperatures, is gradually decomposed. At 20° (68° F.) the decomposi- tion takes place more quickly, and at 100° (212° F.) rapidly and with ef- fervescence. The dilute substance, however, is comparatively stable, and may be boiled and even distilled without suffering decomposition. Hydrogen peroxide acts both as a reducing and an oxidizing agent. Arsenic, sulphides, and sulphur dioxide are oxidized by it at the expense of half its oxygen. When it is brought in contact with silver oxide both substances are violently decomposed, water and elementary silver remain- ing. By certain substances, such as gold, platinum, and charcoal in a state of fine division, fibrin, or manganese dioxide, it is decomposed with evolution of oxygen ; the decomposing agent remaining unchanged. The pure substance, when decomposed, yields 475 times its volume of oxygen ; the dilute 15 to 20 volumes. In dilute solution it is used as a bleaching agent and in the renovation of old oil-paintings. Analytical Characters.—1. To a solution of starch a few drops of cadmium iodide solution are added, then a small quantity of the fluid to be tested, and, finally, a drop of a solution of ferrous sulphate. A blue color is produced in the presence of hydrogen peroxide, even if the solu- tion contain only 0.05 milligram per litre. 2. Add freshly prepared tincture of guaiacum and a few drops of a cold infusion of malt. A blue color—1 in 2,000,000. HYDROGEN DIOXIDE. 53 3. Add the liquid to be tested to mixed solutions of ferric chloride and potassium ferricyanide (which should have no blue tinge). A blue color —1 in 10,000,000. 4. Add to 6 c.c. of the liquid sulphuric acid, iodide of zinc, starch-paste, 2 drops of a two per cent, solution of cupric sulphate, and a little one-half per cent, solution of ferrous sulphate, in the order named. A blue color. Atmospheric Hydrogen Dioxide.—Atmospheric air constantly contains small quantities of hydrogen dioxide, which is also present in rain-water and in hail, and in less proportion in snow and hoar-frost. The amount present in rain-water varies from 0.008 to 0.499 milligram per litre (0.000454 to 0.028 grain per U. S. gallon), according to the direction of the wind and the season of the year. It is more abundant with equa- torial than with polar winds, and more abundant in summer than in winter. 54 MANUAL OF CHEMISTRY. CLASS II.—ACIDULOUS ELEMENTS. Elements all of whose Hydrates are Acids, and which do not form Salts with the Oxacids. I. CHLORINE GROUP. Fluorine. Chlorine. Bromine. Iodine. The elements of this group are univalent. With hydrogen they form acid compounds, comjiosed of one volume of the element in the gaseous state with one volume of hydrogen. Their hydrates are monobasic acids when they exist (fluorine forms no hydrate). The first two are gases, the third liquid, the fourth solid at ordinary temperatures. They are known as the halogens. The relations of their compounds to each other are shown in the following table : HP, HC1, CLO C1,0, CLO. HCIO HC10„ HCIO, hcio4 HBr - HBiO HBrO, HBi04 HI 1,0, HIO HI02 HIO, hio4 Hydro-ic acid. Monoxide. Trioxide. Tetroxide. Hypo-ous acid, -ous acid. -ic acid. Per-ic acid. FLUORINE. Symbol = F—Atomic weight = 19—Discovered by Sir II. Davy in 1812. Although many attempts have been made to isolate this element, it has probably never been obtained in the free state, unless the colorless gas obtained by G. J. and Th. Knox, by the decomposition of mercury fluo- ride and of hydrofluoric acid in vessels of fluor-spar was the element. Fluorine forms compounds with all the other elements except oxygen. Hydrogen Fluoride. Hydrofluoric acid = HF—Molecular weight = 20. Hydrofluoric acid is obtained by the action of an excess of sulphuric acid upon fluor-spar, with the aid of gentle heat: CaFl2 + H.,S04 = CaS04 + 2HF. If a solution be desired, the operation is conducted in a platinum or lead retort, whose beak is connected with a U-shaped receiver of the same metal, which is cooled and contains a small quantity of water. The aqueous acid is a colorless liquid, highly acid and corrosive, and having a penetrating odor. Great care must be exercised that neither the solution nor the gas come in contact with the skin, as they produce pain- ful ulcers which heal with difficulty, and also constitutional symptoms which may last for days. When the acid has accidentally come in contact with the skin the part should be washed with dilute solution of potash, and the vesicle which forms should be opened. CHLOKINE. Both the gaseous acid and its solution remove the silica from glass, a property utilized in etching upon that substance, the parts upon which no action is desired being protected by a coating of wax. The presence of fluorine in a compound is detected by reducing the substance to powder, moistening it with sulphuric acid in a platinum cru- cible, over which is placed a slip of glass prepared as above ; at the end of half an hour the wax is removed from the glass, which will be found to be etched if the substance examined contained a fluoride. CHLORINE. Symbol = Cl—Atomic weight = 35.5—Molecular weight — 71—Sp. gr.= 2.4502 A — One litre weighs 3.17 grams—100 cubic inches weigh 76.3 grains—Name derived from yAxopos = yellowish-green—Discovered by Scheele in 1774. Occurrence.—Only in combination, most abundantly in sodium chlo- ride. Preparation.—(1.) By heating together manganese dioxide and hydro- chloric acid (Scheele). The reaction takes place in two stages : manganic chloride is first formed according to the equation: MnOa + 4HC1 = MnCl4 -t- 2HuO ; and is subsequently decomposed into manganous chlo- ride and chlorine : MnCl4 = MnCl„ -f Cla. This and similar operations are usually conducted in an apparatus such as that shown in Fig. 19. The earthenware vessel A (which on a small scale may be replaced by a glass flask) is two-thirds filled with lumps of manganese dioxide of the size of hazel-nuts, and adjusted in the water-bath; hydrochloric acid is poured in through the safety-tube and the bath heated. The disengaged gas is caused to bubble through the small quantity of water in B, is then dried by passage over the fragments of calcium chloride in C, and is finally collected by displacement of air in the vessel D. When the vessel A has become half filled with liquid it is best to decant the solution of manganous chlo- ride, wash the remaining oxide with water and begin anew. A kilo, of oxide yields 257.5 litres of Cl. Fig. 19. (2.) By the action of manganese dioxide upon hydrochloric acid in the presence of sulphuric acid, manganous sulphate being also formed : MnO., 4- 56 MANUAL OF CHEMISTRY. 2HC1 + H. ,S04 = MnS04 4- 2H,0 4- Cl2. The same quantity of chlorine is obtained as in (1), with the use of half the amount of hydrochloric acid. (3.) By heating a mixture of one part each of manganese dioxide and sodium chloride, with three parts of sulphuric acid. Hydrochloric acid and sodium sulphate are first formed : H S04 + 2NaCl = Na. S04 4- 2HC1; and the acid is immediately decomposed by either of the reactions indi- cated in (1) and (2), according as sulphuric acid is or is not present in excess. (4.) By the action of potassium dicliromate upon hydrochloric acid ; potassium and chromic chlorides being also formed : K Cr.,0, + 14HC1 = 2KC1 + Cr.,Cl„ + TH.,0 4- 3C1.,. Two parts of powdered dicliromate are heated with 17 parts of acid of sp. gr., 1.10 ; 100 grams of the salt yield- ing 22.5 litres of Cl. (5.) When a slow evolution of Cl, extending over a considerable period of time, is desired, as for ordinary disinfection, moistened chloride of lime is exposed to the air, the calcium hypochlorite being decomposed by the atmospheric carbon dioxide. If a more rapid evolution of gas be desired, the chloride of lime is moistened with dilute hydrochloric acid in place of with water. Properties.—Physical.—A greenish yellow gas, at the ordinary tempera- ture and pressure ; it has a penetrating odor, and is, even when highly diluted, very irritating to the respiratory passages. Being soluble in H.,0 to the extent of one volume to three volumes of the solvent, it must be collected by displacement of air, as shown in Fig. 19. A saturated aque- ous solution of Cl is known to chemists as chlorine water, and in phar- macy as aqua chlori (U. S.), Liquor chlori (Hr.); it should bleach, but not redden, litmus paper. Under a pressure of 6 atmospheres at 0° (32° F.), or 8| atmospheres at 12° (53°.G F.), Cl becomes an oily, yellow liquid, of sp. gr. 1.33 ; and boiling at — 33.G° (— 28°.5 F.). Chemical.—Chlorine exhibits a great tendency to combine with other elements, with all of which, except F, O, N, and C, it unites directly, fre- quently with evolution of light as well as heat, and sometimes with an ex- plosion. With H it combines slowly, to form hydrochloric acid, under the influence of diffuse daylight, and violently in direct sunlight or in highly actinic artificial lights. A candle burns in Cl with a faint flame and thick smoke, its H combining with the Cl, while carbon becomes free. At a red heat Cl decomposes H.,0 rapidly, with formation of hydro- chloric acid. The same change takes place slowly under the influence of sunlight, hence chlorine water should be kept in the dark or in bottles of yellow glass. In the presence of H20, chlorine is an active bleaching and disinfect- ing agent. It acts as an indirect oxidant, decomposing H.,0, the nascent O from which then attacks the coloring or odorous principle. Chlorine is readily fixed by many organic substances, either by addi- tion or substitution. In the first instance, as when Cl and olefiant gas unite to form ethylene chloride, the organic substance simply takes up one or more atoms of chlorine : C H, -f Cl, = C2H4C1„. In the second instance, as when Cl acts upon marsh gas to produce methyl chloride : CH4 -t- Cl2 = CH,C1 4- HC1, each substituted atom of Cl displaces an atom of H. which combines with another Cl atom to form hydrochloric acid. Hydrate of chlorine, C15H,0, is a yellowish green, crystalline substance, formed when Cl is passed through chlorine water cooled to 0° (32° F.). It is decomposed at 10° (50° F.). Analytical Characters.—See p. 62. IIYDKOGEN CHLORIDE. Hydrogen Chloride. Hydrochloric Acid.—Muriatic Acid.—Acidum Hydrochloricum (U. S.; Br.)—HC1—Molecular weight = 36.5—Pp. gr., 1.25Q A—A litre weighs 1.6293 gram. Occurrence.—111 volcanic gases and in the gastric juice of the mam- malia. Preparation.—(1.) By the direct union of its constituent elements. (2.) By the action of sulphuric acid upon a chloride, a sulphate being at the same time formed : H S04 + 2NaCl = Na.,S04 + 2HC1. This is the reaction by which the HC1 used in the arts is produced, either as a separate industry or as an incidental product in Leblanc’s pro- cess for obtaining sodium carbonate (q. v.). (3.) Hydrochloric acid is also formed in a great number of reactions, as when Cl is substituted in an organic compound. Properties.—Physical.—A colorless gas, acid in reaction and taste, hav- ing a sharp, penetrating odor, and producing great irritation when in- haled. It becomes liquid under a pressure of 40 atmospheres at 4° (39° F.). It is very soluble in H.,0, one volume of which dissolves 480 volumes of the gas at 0° (32° F.). Chemical.—Hydrochloric acid is neither combustible nor a supporter of combustion, although certain elements, such as Iv and Na, burn in it. It forms white clouds on contact with moist air. Solution of Hydrochloric Acid.—It is in the form of aqueous solution that this acid is usually employed in the arts and in pharmacy. It is, when pure, a colorless liquid (yellow when impure), acid in taste and reaction, whose sp. gr. and boiling-point vary with the degree of concen- tration. When heated, it evolves HC1, if it contain more than 20 per cent, of that gas, and H.,0 if it contain less. A solution containing 20 per cent, boils at 111° (232° F.), is of sp. gr. 1.099, has the composition HC1 + 8H.O, and distils unchanged. Commercial muriatic acid is a yellow liquid ; sp. gr. about 1.16 ; con- tains 32 per cent. HC1 ; and contains iron, sodium chloride, and arsenical compounds. Acidum hydrochloricum is a colorless liquid, containing small quantities of impurities. It contains 31.9 per cent. HC1 and its sp. gr. is 1.16 (U. S. ; Br.). The dilute acid is the above diluted with water. Sp. gr. 1.049 = 10 per cent. HC1 (U. S.) ; sp. gr. 1.052 = 10.5 per cent. HC1 (Br.). C. P. {chemically pure) acid is usually the same as the strong pharma- ceutical acid and far from pure (see below). Hydrochloric acid is classed, along with nitric and sulphuric acids, as one of the three strong mineral acids. It is decomposed by many elements, with formation of a chloride and liberation of hydrogen: 2HC1 + Zn = ZnCl3 + H,. With oxides and hydrates of elements of the third and fourth classes it enters into double decomposition, forming H„0 and a chloride : CaO + 2HC1 = CaCl, + H.,0 or CaH20„ + 2HC1 = CaCl? 4- 2H.O. Most of the metallic chlorides are soluble in H.,0, those of Ag, Pb, and Hg (ous) being exceptions. The chlorides of the non-metals are decomposed on contact with H O. Oxidizing agents decompose HC1 with liberation of Cl. A mixture of hydrochloric and nitric acids in the proportion of three molecules of the former to one of the latter, is the acidum nitrohydrochloricum (U. S.; Br.), 58 MANUAL OF CHEMISTRY. or aqua regia. The latter name alludes to its power of dissolving gold, by combination of the nascent Cl which it liberates with that metal to form the soluble auric chloride. Impurities.—A chemically pure solution of this acid is exceedingly rare. The impurities usually present are : Sulphurous acid—hydrogen sulphide is given off when the acid is poured upon zinc ; Sulphuric acid—a white precipitate is formed with barium chloride ; Chlorine colors the acid yel- low ; Lead gives a black color when the acid is treated with hydrogen sulphide ; Iron—the acid gives a red color with ammonium sulphocyanate ; Arsenic—the method of testing by hydrogen sulphide is not sufficient. If the acid is to be used for toxicological analysis, a litre, diluted with half as much HaO, and to which a small quantity of potassium chlorate has been added, is evaporated over the water-bath to 400 c.c. ; 25 c.c. of sul- phuric acid are then added, and the evaporation continued until the liquid measures about 100 c.c. This is introduced into a Marsh apparatus and must produce no mirror during an hour. Analytical Characters.—See p. 62. Toxicology.—Poisons and, corrosives.—A poison is any substance which, after absorption into the blood, produces death or serious bodily harm. A corrosive is a substance capable of producing death by its chemical action upon a tissue with which it comes in direct contact, without absorption by the blood. Under the above definitions the strong mineral acids act as corrosives rather than as poisons. They produce their injurious results by destroy- ing the tissues with which they come in contact, and will cause death as surely by destroying a large surface of skin as when they are taken into the stomach. The object of the treatment in corrosion by the mineral acids is to neutralize the acid and convert it into a harmless salt. For this purpose the best agent is magnesia (magnesia usta) suspended in a small quantity of water ; or, if this be not at hand, a strong solution of soap. Chalk and the carbonates and bicarbonates of sodium and potassium should not be given, as they generate large volumes of gas. The scrapings of a plas- tered wall, or oil, are entirely useless. The stomach-pump, or any attempt at the introduction of a tube into the oesophagus, is not to be thought of. Compounds of Chlorine and Oxygen. Three compounds of chlorine and oxygen have been isolated, two be- ing anhydrides. They are all very unstable, and prone to sudden and vio- lent decomposition. Chlorine Monoxide—C120—87— = hypochlorous anhydride or oxide, is formed as a blood-red liquid by the action, below 20° (68° F.), of dry Cl upon precipitated mercuric oxide : HgO + 2Cla — HgCla + C1,0. On contact with H,,0 it forms hypochlorous acid, HCIO, which, owing to its instability, is not used industrially, although the hypochlorites of Ca, K, and Na are. Chlorine Trioxide = chlorous anhydride or oxide, Cl9Oa—119—is a yellowisli-green gas, formed by the action of dilute nitric acid upon potas- sium chlorate in the presence of arsenic trioxide. At 50° (122° F.) it ex- plodes. It is a strong bleaching agent; is very irritating when inhaled, and readily soluble in H„0, the solution probably containing chlorous acid, HCIO.,. BROMINE. 59 Chlorine Tetroxide = chlorine peroxide, —135—is a violently ex- plosive body, produced by the action of sulphuric acid upon potassium chlorate. Below — 20° ( — 4° F.), it is an orange-colored liquid ; above that temperature, a yellow gas. There is no corresponding hydrate known ; and if it be brought in contact with an alkaline hydrate, a mix- ture of chlorate and chlorite is formed. Besides the above, two oxacids of Cl are known, the anhydrides cor- responding to which have not been isolated. Chloric Acid—HC103 — 84.5—obtained in aqueous solution as a strongly acid, yellowish, syrupy liquid, by decomposing its barium salt by the proper quantity of sulphuric acid. Perchloric Acid—HC104—100.5—is the most stable of the series. It is obtained by boiling potassium chlorate with liydrofluosilicic acid, de- canting the cold fluid, evaporating until white fumes appear, decanting from time to time, and finally distilling. It is a colorless, oily liquid ; sp. gr. 1.782 ; which explodes on contact with organic substances or charcoal. BROMINE. Symbol = Br—Atomic weight = 80—Molecular weight = 160—Sp. gr. of liquid = 3.1872 at 0° ; of vapor = 5.52 A—Freezing-point — — 24 .5 ( —12°.1 F.)—Boiling-point = 63° (145°.4 F)—Name derived from (3pwy.o<> = a stench.—Discovered by Balard in 182G—Bromum (U. S.; Br.). Occurrence.—Only in combination, most abundantly with Na and Mg in sea-water and the waters of mineral springs. Preparation.—It is obtained from the mother liquors left by the evap- oration of sea-water and of that of certain mineral springs, and from sea- weed. These are mixed with sulphuric acid and manganese dioxide and heated, when the bromides are decomposed by the Cl produced, and Br distils. Properties.—Physical.—A dark reddish brown liquid, volatile at all temperatures above — 24°.5 (— 12°. 1 F.); giving off brown-red vapors which produce great irritation when inhaled. Soluble in water to the extent of 3.2 parts per 100 at 15° (59° F.); more soluble in alcohol, carbon disulphide, chloroform, and ether. Chemical.—The chemical characters of Br are similar to those of Cl, but less active. With H,0 it forms a crystalline hydrate at 0° (32° F.): Br. 5H„0. Its aqueous solution is decomposed by exposure to light, with formation of hydrobromic acid. It is highly poisonous. Analytical Characters.—See p. 62. Hydrogen Bromide. Hydrobromic acid—Acidum hydrobromicum dil. (U. S.) = HBr—Mole- cular weight = 81—Sp. gr. = 2.71 A—A litre weighs 3.63 grams—Liquefies at - 69° (-92°.2 F.)—Solidifies at - 73° (-99°A F.). Preparation.—This substance cannot be obtained from a bromide as HC1 is obtained from a chloride. It is produced, along with phosphorous acid, by the action of H.,0, upon phosphorus tribromide : PBr3 -1- 3H20 = H P03 + 3HBr; or by the action of Br upon paraffine. 60 MANUAL OF CHEMISTRY. Properties.—A colorless gas ; produces white fumes with moist air ; acid in taste and reaction, and readily soluble in HO, with which it forms a hydrate, HBr2HaO. Its chemical properties are similar to those of the corresponding Cl compound. Analytical.—See page 62. Oxacids of Bromine. No oxides of bromine are known, although three oxacids exist, either in the free state or as salts : Hypobromous Acid—HBrO—97—is obtained, in aqueous solution, by the action of Br upon mercuric oxide, silver oxide, or silver nitrate. When Br is added to concentrated solution of potassium hydrate, no hypobro- mite is formed, but a mixture of bromate and bromide, having no decol- orizing action. With sodium hydrate, however, sodium hypobromite is formed in solution ; and such a solution, freshly prepared, is used in Knop’s process for determining urea (q. v). Bromic Acid—HBr03—129—has only been obtained in aqueous solu- tion or in combination. It is formed by decomposing barium bromate with an equivalent quantity of sulphuric acid : Ba (BrOs)a -+- H2S04 = 2 HBr03 -f- BaS04. In combination it is produced, along with the bromide, by the action of Br on caustic potassa: 3Br2 + GKHO = KBrOa + 5KBr -i- 3H20. Peiibromic Acid—HBr04—145—is obtained on a comparatively stable, oily liquid, by the decomposition of perchloric acid by Br, and concentrat- ing over the water-bath. It is noticeable in this connection that, while HC1 and the chlorides are more stable than the corresponding Br compounds, the oxygen com- pounds of Br are more permanent than those of Cl. IODINE. Symbol = I—Atomic iveight = 127—Molecular weight = 254—Sp. gr. of solid = 4.948 ; of vapor = 8.716 A—Fuses at 113°.6 (236°. 5 F.)—Boils at 175° (347° F)—Name derived from tufty s = violet—Discovered by Cour- tois in 1811—Iodum (U. S. ; Br.). Occurrence.—In combination with Na, K, Ca, and Mg, in sea-water, the waters of mineral springs, marine plants and animals ; cod-liver oil contains about 37 parts in 100,000. Preparation.—It is obtained from the ashes of sea-weed, called kelp or varech. These are extracted with II20, and the solution evaporated to small bulk. The mother liquor, separated from the other salts which crystallize out, contains the iodides, which are decomposed by Cl, aided by heat, and the liberated iodine condensed. Properties.—Physical.—Blue-gray, crystalline scales, having a metallic lustre. Volatile at all temperatures, the vapor having a violet color and a peculiar odor. It is sparingly soluble in II ,O, which, however, dissolves larger quantities on standing over an excess of iodine, by reason of the formation of hydriodic acid. The presence of certain salts, notably potas- sium iodide, increase the solvent power of H,0 for iodine. The Liq. Iodi HYDROGEN IODIDE. 61 Comp. (V. S), (Liq. Iodi, Br.) is solution of potassium iodide containing free iodine. Very soluble in alcohol; Tinct. iodi (U. S. ; Br ) ; in ether chloroform, benzol, and carbon disulphide. With the three last-named solvents it forms violet solutions, with the others brown solutions. Chemical.—In its chemical characters I resembles Cl and Br, but is less active. It decomposes H20 slowly and is a weak bleaching and oxidizing agent. It decomposes hydrogen sulphide with formation of hydriodic acid and liberation of sulphur. It does not combine directly with oxygen, but does with ozone. Potassium hydrate solution dissolves it, with for- mation of potassium iodide and some liypoiodite. Nitric acid oxidizes it to iodic acid. With ammonium hydrate solution it forms the explosive nitrogen iodide. Impurities. — Non-volatile substances remain when the I is volatilized. Water separates as a distinct layer when I is dissolved in carbon disulph- ide. Cyanogen iodide appears in white, acicular crystals among the crys- tals of sublimed I when half an ounce of the substance is heated over the water-bath for twenty minutes, in a porcelain capsule, covered with a flat-bottomed flask tilled with cold water. The last named is the most serious impurity as it is actively poisonous. Toxicology.—Taken internally, iodine acts both as a local irritant and as a true poison. It is discharged as an alkaline iodide by the urine and perspiration, and when taken in large quantity it appears in the faeces. The poison should be removed as rapidly as possible by the use of the stomach-pump and of emetics. Farinaceous substances may also be given. Analytical Characters.—See below. Hydrogen Iodide. Hydriodic acid—HI—Molecular weight = 128—Sp. gr. 4.443 A. Preparation.—By the decomposition of phosphorous triiodide by water: PI, + 3H„0 — H;P03 + 3HI. Or, in solution, by passing hydrogen sulph- ide through water holding iodine in suspension : H.,S + I2 = 2HI -+- S. Properties.—A colorless gas, forming white fumes on contact with air, and of strong acid reaction. Under the influence of cold and pressure it forms a yellow liquid, which solidities at —55° ( — 67° F.). Water dissolves it to the extent of 425 volumes for each volume of the solvent at 10° (50° F.). It is partly decomposed into its elements by heat. Mixed with O it is decomposed, even in the dark, with formation of H20 and liberation of I. Under the influence of sunlight the gas is slowly decomposed, although its solutions are not so affected, if they be free from air. Chlorine and bro- mine decompose it, with liberation of iodine. With many metals it forms iodides. It yields up its H readily and is used in organic chemistry as a source of that element in the nascent state. Analytical Characters.—Chlorine, Bromine, and Iodine, and their Bi- nary Compounds.—Chlorine.—(1.) Color. (2.) Odor. (3.) Is dissolved by solutions of the alkaline hydrates, to which it com- municates bleaching powers. (4.) With silver nitrate solution it gives a white ppt., soluble in NH HO, insoluble in HN03. Bromine.—(1.) Color of liquid and vapor. MANUAL OF CHEMISTRY. (2.) Chloroform or carbon disulphide, when shaken with solution of Br, assume a yellow or brown color. (3.) Colors starch paste yellow. Iodine.—(1.) Color of vapor. (2.) Dissolves in chloroform and carbon disulphide with a violet color. (3.) Colors starcli-paste deep violet-blue, the color disappearing on heating and returning on cooling. Chlorides.—(1.) With AgN03. a white ppt., insoluble in HN03, readily soluble in NH4HO. (2.) With Hg„(NO.,)„, a white ppt., which turns black with NHHO. Bromides.—(i.) With AgNO,, a yellowish-white ppt., insoluble in H N03, sparingly soluble in KH4HO. (2.) With chlorine water, a yellow color, and when shaken with chloro- form the latter is colored yellow ; or colors starcli-paste yellow. Iodides.—(1.) With AgNOs, a yellowish-white ppt., insoluble in HN03, almost insoluble in NH4HO. (2.) With fuming HNO,t, a yellow color, and when shaken with chloro- form the latter is colored violet; or colors starcli-paste dark blue. (3.) With PdCl4, a dark brown ppt. Oxacids of Iodine. The best known of these are the highest two of the series—iodic and periodic acids. Iodic Acid—HI03—176 — is formed as an iodate, whenever I is dis- solved in a solution of an alkaline hydrate : I8 + 6KHO = KI03 + 5KI + 3H..0 ; as the free acid, by the action of strong oxidizing agents, such as nitric acid or chloric acid, upon I; or by passing Cl for some time through HO holding I in suspension. Iodic acid appears in white crystals, decomposable at 170° (338° F.), and quite soluble in H20, the solution having an acid reaction, and a bit- ter, astringent taste. It is an energetic oxidizing agent, yielding up its O readily, with sepa- ration of elementary I or of HI. It is used as a test for the presence of morphine (q. v.). Periodic Acid—HI04—192—is formed by the action of Cl upon an al- kaline solution of sodium iodate. The sodium salt thus obtained is dis- solved in nitric acid, treated with silver nitrate, and the resulting silver periodate decomposed with H,0. From the solution the acid is obtained in colorless crystals, fusible at 130° (2663 F.), very soluble in water, and readily decomposable by heat. n. SULPHUR GROUP. Sulphur—Selenium—Tellurium. The elements of this group are bivalent. With hydrogen they form compounds composed of one volume of the element, in the form of vapor, with two volumes of hydrogen—the combination being attended with a condensation in volume of one-tliird. Their hydrates are dibasic acids SULPHUR. 63 They are all solid at ordinary temperatures. The relation of their com- pounds to each other are shown in the following table : HS SO, SO, H SO, H.SO, h.,so4 H.,Se SeOa SeO, H.SeO, H.SeO, HTe TeO., TeO, HjTeOa H„Te04 Hydro-ic acid. Dioxide. Trioxide. Hypo-ous acid. -ous acid. -ic acid. SULPHUR. Symbol — S—Atomic weight = 32—Molecular weight = 64—Sp. gr. of vapor — 2.22 A—Fuses at 114° (237.2° F.)—Boils at 447.3° (837° F.). Occurrence.—Free in crystalline powder, large crystals, or amorphous in volcanic regions. In combination in sulphides and sulphates, and in albuminoid substances. Preparation.—By purification of the native sulphur, or decomposition of pyrites, natural sulphides of iron. Crude sulphur is the product of a first distillation. A second distilla- tion in more perfectly constructed apparatus yields refined sulphur. Dur- ing the first part of the distillation, while the air of the condensing cham- ber is still cool, the vapor of S is suddenly condensed into a fine, crystal- line powder, which is fioivers of sulphur, sulphur sublimatum (U. /S.). Later, when the temperature of the condensing chamber is above 114°, the liquid S collects at the bottom, whence it is drawn oft’ and cast into sticks of roll sulphur. Properties.—Physical.—Sulphur is usually yellow in color ; at low tem- peratures, and in minute subdivision, as in the precipitated milk of sulphur, sulphur prcecipitatum (U. S.), it is almost or quite colorless. Its taste and odor are faint but characteristic. At 114° (237°.2 F.) it fuses to a thin yel- low liquid, which at 150o-lG0° (302°-320° F.) becomes thick and brown ; at 330°-340J (6263-642°.2 F.) it again becomes thin and light in color; finally it boils, giving oft’ brownish-yellow vapor at a temperature variously stated between 440° (824° F) and 448° (838°.4 F.). If heated to about 400° (752° F.) and suddenly cooled it is converted into plastic sulphur, which may be moulded into any desired form. It is insoluble in water, sparingly soluble in anilin, phenol, benzol, benzine, and chloroform ; read- ily soluble in protochloride of sulphur and carbon disulphide. It is di- morphous ; when fused sulphur crystallizes it does so in oblique rhombic prisms ; its solution in carbon disulphide deposits it on evaporation in rhombic octahedra. The prismatic variety is of sp. gr. 1.95 and fuses at 120° (248° F.) ; the sp. gr. of the octahedral is 2.05, and its fusing point 114°.5 (238° F.). The prismatic crystals by exposure to air become opaque, by reason of a gradual conversion into octahedra. Chemical.—Sulphur unites readily with other elements, especially at high temperatures. Heated in air or O, it burns with a blue flame to sul- phur dioxide, S02. In H it burns with formation of hydrogen sulphide, H,S. The compounds of S are similar in constitution, and to some extent in chemical properties, to those of O. In many organic substances S may replace O, as in sulphocyanic acid, CNSH, corresponding to cyanic acid, CNOH. Uses.—Sulphur is used principally in the manufacture of gunpowder ; also to some extent in making sulphuric acid, sulphur dioxide, and matches, and for the prevention of fungoid and parasitic growths. 64 MANUAL OF CHEMISTRY. Hydrogen Sulphide. Sulphydric acid—Hydrosulphuric acid—Sulphuretted hydrogen. H2S—Molecular weight = 34—Sp. gr. = 1.19 A. Occurrence.—In volcanic gases ; as a product of the decomposition of organic substances containing S ; in solution in the waters of some min- eral springs ; and occasionally in small quantity in the gases of the intes- tine. Preparation.—(1.) By direct union of the elements ; either by burning S in H, or by passing H through molten S. (2.) By the action of nascent H upon sulphuric acid if the mixture be- come heated. (See Marsh test for arsenic.) (3.) By the action of HC1 upon antimony trisulphide: SbaS3 + 6HC1 = 2SbCla + 3H,S. (4.) By the action of dilute sulphuric acid upon ferrous sulphide: FeS + H S04 = FeS04 + H,S. (5.) By the action of HC1 upon calcium sulphide : CaS + 2HC1 = CaCb f H2S. The gas is usually obtained in the laboratory by reaction (4), cither in an apparatus such as that shown in Fig. 17 (p. 41) or in one of the forms of apparatus shown in Figs. 20, 21. The sulphide is put into the bulb 6, Fig. 20, through the opening e, or into the bottle 6, Fig. 2i. The dilute acid with which the upper- Fig. 20. Fig. 21. most and lowest bulbs, Fig. 20, are filled comes in contact w ith the sulphide when the stopcock is opened, or in the apparatus, Fig. 21, is poured through the funnel tube c. a is a wash-bottle partly filled with water. As ferrous sulphide is liable to contain arsenic, and as hydrogen sulphide generated from it may be con- taminated with hydrogen arsenide, the gas, when required for toxicological analysis should always be ob- tained by reaction (5) in the apparatus, Fig. 20. Properties.—Physical.—A colorless gas, having tlie odor of rotten eggs and a disgusting taste; soluble in H„0 to the extent of 3.23 parts to 1 at 15° (59° F.); soluble in alcohol. Under 17 atmospheres pressure, or at — 74° ( — 101°.2 F.) at the ordinary pressure, it liquefies; at — 85.5° ( — 122° F.) it forms white crystals. 11YDK0GEJN SULPHIDE. Chemical.—Burns in air with formation of sulphur dioxide and water : 2H2S + 30a = 2SO„ + 2H,0. If the supply of oxygen be deficient, H.,0 is formed and sulphur liberated : 2H2S -+ 02 = 2H.,0 + S4. Mixtures of H2S and air or O explode on contact with flame. Solutions of the gas when ex- posed to air become oxidized with deposition of S. Such solutions should be made with boiled H.,0 and kept in bottles which are completely filled and well corked. Oxidizing agents, Cl, Br, and I remove its H with depo- sition of S. Hydrogen sulphide and sulphur dioxide mutually decompose each other into water, pentathionic acid and sulphur: 4S0.2 + 3H..S — 2H.P + H.,S6Ob + S, When the gas is passed through a solution of an alkaline hydrate its S displaces the O of the hydrate to form a sulphydrate : H.S -4- KHO = H.,0 + KHS. With solutions of metallic salts H2S usually relinquishes its S to the metal: On SO, -f H.,S = CuS -f H2S04, a property which renders it of great value in analytical chemistry. Analytical Characters — Hydrogen sulphide.—(1.) Blackens paper moistened with lead acetate solution. (2.) Has an odor of rotten eggs. Sulphides.—(1.) Heated in the oxidizing flame of the blowpipe, give a blue flame and odor of S02. (2.) With a mineral acid give off' HsS (except sulphides of Hg, Au, and Pt). * Physiological.—Hydrogen sulphide is produced in the intestine by the decomposition of albuminous substances or of taurochloric acid ; it also occurs sometimes in abscesses, and in the urine in tuberculosis, variola, and cancer of the bladder. It may also reach the bladder by diffusion from the rectum. Toxicology.—An animal dies almost immediately in an atmosphere of pure H.,S, and the diluted gas is still rapidly fatal. An atmosphere con- taining one per cent, may be fatal to man, although individuals habituated to its presence can exist in an atmosphere containing three per cent. Even when highly diluted it produces a condition of low fever, and care is to be taken that the air of laboratories in which it is used shall not become con- taminated with it. Its toxic powers are due primarily, if not entirely, to its power of reducing and combining with the blood-coloring matter. The form in which hydrogen sulphide generally produces deleterious effects is as a constituent of the gases emanating from sewers, privies, burial vaults, etc. These give rise to either slow poisoning, as when sewer gases are admitted to sleeping and other apartments by defective plumbing, or to sudden poisoning, as when a person enters a vault or other locality containing the noxious atmosphere. The treatment should consist in promoting the inhalation of pure air, artificial respiration, cold affusions, and the administration of stimulants. After death the blood is found to be dark in color, and gives the spec- trum shown in Fig. 22, due to sulphasmoglobin. Fig. 22. 66 MANUAL OF CHEMISTRY. Sulphur Dioxide. Sulphurous oxide, anhydride or acid—Acidum sulphurosum (U. S. ; Br.)—SO,—Molecular weight — 64—Sp. gr. of gas = 2.213 ; of liquid = 1.45—Boils at - 10° (14° F.); solidifies at - 75° (- 103° F.). Occurrence.—In volcanic gases and in solution in some mineral waters. Preparation.—(1.) By burning S in air or O. (2.) By roasting iron pyrites in a current of air. (3.) During the combustion of coal or coal-gas containing S or its compounds. (4.) By heating sulphuric acid with copper : 2H.,S04 4- Cu = CuS04 -r 2H20 4- S02. (5.) By heating sulphuric acid with charcoal: 2H,S04 + C = 2SO., 4- C02 + 2H20. When the gas is to be used as a disinfectant it is usually obtained by reaction (1) ; in sulphuric acid factories (2) is used; (3) indicates the method in which atmospheric SO, is chiefly produced ; in the labora- tory (4) is used ; (5) is the process directed by the U. S. and Br. Pliar- macopseias. Properties.—Physical.—A colorless, suffocating gas, having a disagree- able and persistent taste. Very soluble in H,0, which at 15° (59° F.) dissolves about 40 times its volume (see below) ; also soluble in alcohol. At — 10° (14° F.) it forms a colorless, mobile, transparent liquid, by whose rapid evaporation a cold of — 65° ( — 85° F.) is obtained. Chemical.—Sulphur dioxide is neither combustible nor a supporter of combustion. Heated with H it is decomposed : S02 4- 2H, = S 4- 2H20. With nascent hydrogen H„S is formed : S02 + 3H, = H„S 4- 2H,0. Water not only dissolves the gas but combines with it to form the true sulphurous acid, H,S03. With solutions of metallic hydrates it forms metallic sulphites: SO, 4- KHO = KHSO, or SO, 4- 2KHO = K,SOt + H,0. A hydrate having the composition H„S03, 8H20 has been obtained as a crystalline solid, fusible at -f 4° (39°. 2 F.). Sulphur dioxide and sulphurous acid solution are powerful reducing agents, being themselves oxidized to sulphuric acid : SO, -I- H„0 4 O = H S04 or H,S03 4- O = H,S04. It reduces nitric acid with formation of sulphuric acid and nitrogen tetroxide: SO, 4- 2HN03 = H2S04 4- 2NO,. It decolorizes organic pigments, without, however, destroying the pig- ment, whose color may bo restored by an alkali or a stronger acid. It destroys H2S, acting in this instance, not as a reducing, but as an oxidiz- ing agent: 4S02 4- 3H,S = 2H,0 4- H,S606 4- S„. With Cl it combines directly under the influence of sunlight to form sulphuryl chloride (S02) " Cl2. Sulphurous acid is dibasic. Analytical Characters.—(1.) Odor of burning sulphur. (2.) Paper moistened with starcli-paste and iodic acid solution turns blue in air containing 1 in 3,000 of SO,. Sulphites.—(1.) With HC1 give off S02. (2.) With Zn and HC1 give off H2S. (3.) With AgNOa a white ppt., soluble in excess of sulphite. When the mixture is boiled elementary Ag is deposited. (4.) With Ba(N03)„ a white ppt., soluble in HC1. Solution of Cl added to this solution forms a white ppt., insoluble in acids. SULPHURIC ACID. 67 Sulphur Trioxide. Sulphuric oxide or anhydride—SOa—Molecular weight = 80—Sp. gr. 1.95—Fuses at 18.3° (65° F.)—Boils at 46° (114.8° F.). Preparation.—(1.) By union of S02 and O at 250°-300° (482°-572° F.) or in presence of spongy platinum. (2.) By heating sulphuric acid in presence of phosphoric anhydride : H2S04 + P205 = «03 + 2HP03. (3.) By heating dry sodium pyrosulphate : Na.,S207 = Na.,S04 + S03. (4.) By heating pyrosulphuric acid below 100° (212° F.) in a retort fitted with a receiver, cooled by ice and salt: H„S207 = H..S04 + S03. Properties.—White, silky, odorless crystals which give off white fumes in damp air. It unites with H20 with a hissing sound and elevation of temperature to form sulphuric acid. When dry it does not redden litmus. Oxacids ot Sulphur. H,S02 Hydrosulphurous acid. H. ,S03 Sulphurous acid. H.,S04 Sulphuric acid. H,S207 Pyrosulphuric acid. H„S,0(. Dithionic acid. H,S306 Trithionic acid. H2S406 Tetrathionic acid. H„S.06 Pentathionic acid. H2S203 Hyposulpliurous acid. Hydrosulphurous Acid—H2S02—66. Is an unstable body only known in solution, obtained by the action of zinc upon solution of sulphurous acid. It is a powerful bleaching and deoxidizing agent. Sulphuric Acid. Oil of Vitriol—Acidum sulphuricum (U. S.; Br.)—H2S04—98. Preparation.—(1.) By the union of sulphur trioxide and water : SO + H,0 = H2S04. (2.) By the oxidation of SO, or of S in the presence of water : 2SO -f- 2H..0 + O, rz 2H.,S04; or S2 + 2H,0 + 30, = 2H.2S04. The manufacture of H2S04 may be said to be the basis of all chemical industry, as there are but few processes in chemical technology into some part of which it does not enter. The method followed at present, the re- sult of gradual improvement, may be divided into two stages : 1st, the formation of a dilute acid ; 2d, the concentration of this product. The first part is carried on in immense chambers of timber, lined with lead, and furnishes an acid having a sp. gr. of 1.55, and containing 65 per cent, of true sulphuric acid, H,S04. Into these chambers SO.,, obtained by burning sulphur or by roasting pyrites, is driven along with a large excess of air. In the chambers it comes in contact with nitric acid, at the expense of which it is oxidized to H.S04, while nitrogen tetroxide (red fumes) is formed : SO., + 2HN0., = H2S04 -4- 2N0,. Were this the only reaction, the disposal of the red fumes would present a serious difficulty 68 MANUAL OF CHEMISTRY. and tlie amount of nitric acid consumed would be very great. A second reaction occurs between the red fumes and H.,0, which is injected in the form of steam, by which nitric acid and nitrogen dioxide are produced : 3NO., -f H20 = 2HN03 + NO. The nitrogen dioxide in turn combines with O to produce the tetroxide, which then regenerates a further quan- tity of nitric acid, and so on. This series of reactions is made to go on continuously, the nitric acid being constantly regenerated, and acting merely as a carrier of O from the air to the S02, in such manner that the sum of the reactions may be represented by the equation : 2S02 + 2H20 + O, = 2H2S04. The acid is allowed to collect in the chambers until it has the sp. gr. 1.55, when it is drawn off. This chamber acid, although used in a few in- dustrial processes, is not yet strong enough for most purposes. It is con- centrated, first by evaporation in shallow leaden pans until its sp. gr. reaches 1.746 ; at this point it begins to act upon the lead, and is transferred to platinum stills, where the concentration is completed. Varieties.—Sulphuric acid is met with in several conditions of concen- tration and purity : (1.) The commercial oil of vitriol, largely used in manufacturing pro- cesses, is a more or less deeply colored, oily liquid, varying in sp. gr. from 1.833 to 1 842, and in concentration from 93 per cent, to 99£ per cent, of true H2S04. (2.) C. P. acid = Acidum sulphuricum, U. S. ; Br., of sp. gr. 1.84, col- orless and comparatively pure (see below). (3.) Glacial sulphuric acid is a hydrate of the composition H.,S04,H.,0, sometimes called bihydrated sulphuric acid, which crystallizes in rhombic prisms, fusible at + 8°.5 (47°. 3 F.) when an acid of sp. gr. 1.788 is cooled to that temperature. (4.) Ac. sulph. dil. (U. S. ; Br.) is a dilute acid of sp. gr. 1.069 and containing between 9 and 10 per cent. H2S04 (U. S.), or of sp. gr. 1.094, containing between 12 and 13 per cent. H.,S04 (Br.). Properties.—Physical.—A colorless, heavy, oil}' liquid ; sp. gr. 1.842 at 12° (53°.6 F.); crystallizes at 10°.5 (50°.9 F.) ; boils at 338° (640°.4 F.), It is odorless, intensely acid in taste and reaction, and highly corrosive. It is non-volatile at ordinary temperatures. Mixtures of the acid with H.,0 have a lower boiling-point and lower sp. gr. as the proportion of H O in- creases. Chemical.—At a red heat vapor of H2S04 is partly dissociated into S03 and H.,0 ; or, in the presence of platinum, into S02,H.,0 and O. When heated with S, C, P, Hg, Cu, or Ag, it is reduced, with formation of S02. Sulphuric acid has a great tendency to absorb H20, the union being attended with elevation of temperature, increase of bulk and diminution of sp. gr. of the acid, and contraction of volume of the mixture. Three parts, by weight, of acid of sp. gr. 1.842, when mixed with one part of H,0 produce an elevation of temperature to 130° (266° F.), and the re- sulting mixture occupies a volume less than the sum of the volumes of the constituents. Strong H2S04 is a good desiccator of air or gases. It should not be left exposed in uncovered vessels lest, by increase of volume, it overflow. When it is to be diluted with H.,0, the acid should be added to the H20 in a vessel of thin glass, to avoid the projection of particles or the rupture of the vessel. It is by virtue of its affinity for H.,0 that H„SO , chars or dehydrates organic substances. Sulphuric acid is a powerful di- basic acid. Impurities.—The commercial acid is so impure that it is only fit for SELENIUM. 69 manufacturing and the coarsest chemical uses. The so-called C. P. acid may further contain : Lead ; becomes cloudy when mixed with 10 times its volume of H.,0, if the quantity of Pb be sufficient; the dilute acid gives a black color with H„S. Salts; leave a fixed residue when the acid is evaporated. Sulphur dioxide; gives off H.,S when the acid, diluted with an equal volume of H30, comes in contact wuth Zn. Carbon ; communi- cates a brown color to the acid. Arsenic; is very frequently present. When the acid is to be used for toxicological analysis, the test by H3S is not sufficient; the acid, diluted with an equal volume of H.,0, is to be in- troduced into a Marsh apparatus, in which no visible stain should be pro- duced during an hour. Oxides of nitrogen ; are almost invariably present; they communicate a pink or red color to pure brucine. Analytical Characters.—(1.) Barium chloride (or nitrate) ; a white ppt., insoluble in acids. The ppt., dried and heated with charcoal, forms BaS, which, with HC1, gives off H,S. (2.) Plumbic acetate forms a white ppt., insoluble in dilute acids. (3.) Calcium chloride forms a white ppt., either immediately or on di- lution with two volumes of alcohol, insoluble in dilute HC1 or HN03. Toxicology.—Sulphuric acid is an active corrosive and may be, if taken in sufficient quantity in a highly diluted state, a true poison. The concentrated acid causes death, either within a few hours by corrosion and perforation of the walls of the stomach and oesophagus, or, after many weeks, by starvation due to destruction of the gastric mucous membrane and closure of the pyloric orifice of the stomach. The treatment is the same as that for corrosion by HC1. (See p. 58.) Pyrosulphuric Acid. Fuming sulphuric acid -— Nordhausen oil of vitriol — Disulphuric hy- drate—H„S,07—Molecular weight = 178—Sp. gr. = 1.9—Boils at 52.c2 (126° F.). Preparation.—By distilling dry ferrous sulphate ; and purification of the product by repeated crystallizations and fusions, until a substance fusing at 35° (95° F.) is obtained. Properties.—The commercial Nordhausen acid, which is a mixture of H.,S207 with excess of SO,, or of H„S04, is a brown, oily liquid, which boils below 100° (212° F.) giving oft' SO, ; and is solid or liquid according to the temperature. SELENIUM. Symbol = Se—Atomic weight = 79.5—Molecular weight — 159—Sp. gr. of solid = 4.788 ; of vapor = 5.68A—Name from atXyvy = moon—Dis- covered by Berzelius in 1817. A rare element, occurring in combination with Cu, Fe, Ag and Hg and accompanying S. It is capable of existing in three allotropic forms. Its compounds are similar in constitution to those of S. 70 MANUAL OF CHEMISTRY. TELLURIUM. Symbol = Te—Atomic weight = 128—Molecular weight = 256—Sp. gr. of s.olid — 6.25 ; of vapor = 9.0 A—Name from tellus = earth—Discovered in 1782 by Muller. One of the least common of the elements, it occurs free and com- bined with Bi, Pb, Ag, Sb, Ni and Au. It is solid, has a metallic lustre, fuses at about 500° (932° F.). Its compounds are similar to those of Se and S. III. NITROGEN GROUP Nitrogen—Phosphorus—Arsenic—Antimony. The elements of this group are either trivalent or quinquivalent. With hydrogen they form non-acid compounds composed of one volume of the element in the gaseous state with three volumes of hydrogen, the union being attended with a condensation of volume of one-half. Their hy- drates are acids containing one, two, three, or four atoms of replaceable hydrogen. Bismuth, frequently classed in this group, is excluded, owing to the existence of the nitrate Bi(N03)3. The relations existing between the compounds of the elements of tins group are shown in the following table : NHa, Ns0, NO, Na03, no3Jn,o5, — — - hno3 PH,, P,Os, - PA, h3po2, H PO.„ h3po„ h4p2o4, hpo3 AsH . i As203, — AsA> — H,As03, H3As04, H4As20., HAs03 SbH, , — — Sb,03) — Sb„Os, — H3Sb04, H4Sb20i, HSb03 Hyd- ride. Mon- Di- Tri- oxide. oxide, oxide. Tetr- Pent- oxide. oxide. Hvpo-ons acid. -ous acid. Ortho-ic - Pyro-ic Meta-ic acid. acid. acid. NITROGEN. Azote—Symbol = N—Atomic weight = 14—Molecular weight = 28—Sp. gr. — 0.9701—One litre weighs 1.254 grams—Name from vlrpov = nitre, yeveats = source; or from a, privative &i] — life—Discovered by Mayow in 1669. Occurrence.—Free in atmospheric air and in volcanic gases. In com- bination in the nitrates, in ammoniacal compounds and in a great num- ber of animal and vegetable substances. Preparation.—(1.) By removal of O from atmospheric air, or by burn- ing P in air, or by passing air slowly over red-hot copper. It is contam- inated with CC\, H.,0, etc. (2.) By passing Cl through excess of ammonium hydrate solution. If ammonia be not maintained in excess, the Cl reacts with the ammonium chloride formed, to produce the explosive nitrogen chloride. (3.) By heating ammonium nitrite : or a mixture of ammonium chlo- ride and potassium nitrite. Properties —A colorless, odorless, tasteless, non-combustible gas ; not a supporter of combustion ; very sparingly soluble in water. It is very slow to enter into combination, and most of its compounds NITKOGEN. 71 are very prone to decomposition, which may occur explosively or slowly. Nitrogen combines directly with O under the influence of electric dis- charges ; and with H under like conditions and indirectly during the decomposition of nitrogenized organic substances. Nitrogen is not poisonous, but is incapable of supporting respiration. Atmospheric Air. The alchemists considered air as an element until Mayow in 1669 demonstrated its complex nature. It was not, however, until 1770 that Priestley repeated the work of Mayow ; and that the compound nature of air and the characters of its constituents were made generally known by the labors (1770-1781) of Priestley, Butherford, Lavoisier and Cavendish. The older chemists used the terms gas and air as synonymous. Composition.—Air is not a chemical compound, but a mechanical mix- ture of O and N with smaller quantities of other gases. Leaving out of consideration about 0.4 to 0.5 per cent, of other gases, air consists of 20.93 O and 79.07 N, by volume ; or 23 O and 77 N, by weight; pro- portons which vary but very slightly at different times and places ; the extremes of the proportion of O found having been 20.908 and 20.999. That air is not a compound is shown by the fact that the' proportion of its constituents does not represent a relation between their atomic weights or between any multiples thereof; as wTell as by the solubility of air in wrater. Were it a compound it would have a definite degree- of solubility of its own, and the dissolved gas would have the same composition as when free. But each of its constituents dissolves in HaO according to its own solubility and air dissolved in H.,0 at 13° (55°.4 F.) consists of N and O, not in the proportion given above, but in the proportion 65.27 to 34.72. Besides these two main constituents, air contains about 4-5 thous- andths of its bulk of other substances : vapor of water, carbon dioxide, ammoniacal compounds, hydrocarbons, ozone, oxides of nitrogen, and solid particles held in suspension. Vapor of xcater.—Atmospheric moisture is either visible, as in fogs and clouds, when it is in the form of a finely divided liquid ; or invisible, as vapor of water. The amount of HaO which a given volume of air can hold without precipitation varies according to the temperature. • It hap- pens rarely that air is as highly charged with moisture as it is capa- ble of being for the existing temperature. The difference between the amount of water which the air is capable of holding at the existing tem- perature and that which it actually does hold is its fraction of satu- ration, or hygrometric state. Ordinarily air contains from 66 to 70 per cent, of its possible amount of moisture ; if the quantity be less than this the air is too dry and causes a parched sensation and the sense of “ stuffiness ” so common in furnace-heated houses ; if it be greater, evapor- ation from the skin is impeded and the air is oppressive if warm. The actual amount of moisture in air is determined by passing a known volume through tubes filled with calcium chloride ; whose increase in ■weight represents the amount of H.,0 in the volume of air used. The frac- tion of saturation is determined by instruments called hygrometers, hygro- scopes or psychrometers. Carbon dioxide.—The quantity of carbon dioxide in free air varies from 3 to 6 parts in 10,000 by volume. (See Carbon dioxide.) Ammoniacal compounds. —Carbonate, nitrate, and nitrite of ammonium 72 MANUAL OF CHEMISTRY. occur in small quantity (0.1 to G.O parts per million of NH3) in air, as products of the decomposition of nitrogenized organic substances. They are absorbed and assimilated by plants. Nitric and nitrous acids, usually in combination with ammonium, are produced either by the oxidation of combustible substances containing N, or by direct union of N and H ,0 during discharges of atmospheric electricity. Rain-water falling during thunder-showers has been found to contain as much as 3.71 per million of HN03. Sulphuric and sulphurous acids occur in combination with NH4 in the air over cities and manufacturing districts, where they are produced by the oxidation of S existing in coal and coal-gas. Hydrocarbons have been de- tected in the air of cities and of swampy places, in small quantities. Solid particles of the most di- verse nature are always present in air and become visible in a beam of sunlight. Chloride of sodium is almost always present, always in the neighborhood of salt water. Air contains myriads of germs of vegetable organisms, mould, etc., which are propagated by the trans- portation of these germs by air- currents. Whether or no certain diseases are thus propagated by germs or poisons ; and whether low forms of organized beings can or cannot make their appearance without the introduction of germs are questions, both sides of which are supported by active partisans, and concerning which little or nothing is known with certainty. The continued inhalation of air containing large quantities of solid par- ticles in suspension may cause severe pulmonary disorder by mere mechani- cal irritation, and apart from any poisonous quality in the substance ; such is the case with the air of carpeted ball-rooms, and of the workshops of certain trades, furniture-polishers, metal-filers, etc. Fig. 23. Atmospheric dust is best collected by an instrument such as is shown in Pig. 23. A disk of thin glass is fastened upon the plate b, over the small opening in A, and its lower surface moistened with a mixture of equal parts of water and glycerin, the opening C is connected with an aspirator. After one or more cubic metres of air have been dratfn through the apparatus, the thin glass is detached and the deposit examined microscopically. Ammonia. Hydrogen nitride—Volatile alkali- N"H,—Molecular weight = 17—Sp. gr.= 0.589A—Liquefies at -40° (- 40° F.)—Boils at - 33°.7 (- 28°.7 F.)—Solidifies at —75° ( —103° F.)—A litre weighs 0.7655 grams. Preparations.—(1.) By union of nascent H with N. (2.) By decomposition of organic matter containing N, either spon- taneously or by destructive distillation. NITROGEN MONOXIDE. 73 (3.) By heating a mixture of dry slacked lime with ammonium chloride : 2NH4C1 + CaH.,0,, = CaCl, + 2H,0 + 2NH3. (4.) By heating solution of ammonium hydrate : NH4HO = N1I3 + H.,0. Properties.—Physical.—A colorless gas, having a pungent odor and an acrid taste. It is very soluble in H.,0, 1 volume of which at 0° (32° F.) dissolves 1050 vols. NHa and at (59° F.), 727 vols. NH3. Alcohol and ether also dissolve it readily. Liquid ammonia is a colorless, mobile fluid, used in ice machines for producing artificial cold, the liquid absorb- ing a great amount of heat in volatilizing. Chemical.—At a red heat ammonia is decomposed into a mixture of N and H, occupying double the volume of the original gas. It is similarly decomposed by the prolonged passage through it of discharges of elec- tricity. It is not readily combustible, yet it burns in an atmosphere of 0 with a yellowish flame. Mixtures of NH3 with O, nitrogen monoxide, or nitrogen dioxide, explode on contact with flame. Water dissolves am- monia with elevation of temperature and probably with formation of ammonium hydrate, NH4HO (q. v.). It combines directly with acids to produce ammonium salts, without separation of hydrogen. (See Ammo- nium.) Nitrogen Monoxide Nitrous oxide—Lauyhiuy gas—Nitrogen protoxide—IT.,O—Molecular weight = 44—Sp. gr. = 1.527J—Fuses at —100° ( — 148° F.)—Boils at —87° ( — 124° F.)—Discovered in 1776 by Priestley. Preparation.—By heating ammonium nitrate : (NH4)N03 = N.,0 + 2 H20. To obtain a pure product there should be no ammonium chloride present (as an impurity of the nitrate), and the heat should be applied gradually and not allowed to exceed 250° (482° F.), and the gas formed should be passed through wash-bottles containing sodium hydrate and ferrous sulphate. Properties.—Physical.—A colorless, odorless gas, having a sweetish taste ; soluble in H.,0, more so in alcohol. Under a pressure of 30 atmo- spheres, at 0° (32° F.), it forms a colorless, mobile liquid, which, when dissolved in carbon disulphide and evaporated in vacua, produces a cold of -140° (- 220° F.) Chemical.—It is decomposed by a red heat and by the continuous passage of electric sparks. It is not combustible, but is, after oxygen, the best supporter of combustion known. Physiological.—Although, owing to the readiness with which N.,0 is decomposed into its constituent elements, and the nature and relative pro- portions of these elements, it is capable of maintaining respiration longer than any gas except oxygen or air ; an animal will live for a short time only in an atmosphere of pure nitrous oxide. When inhaled, diluted with air, it produces the effects first observed by Davy in 1799 : first an exhil- aration of spirits, frequently accompanied by laughter, and a tendency to muscular activity, the patient sometimes becoming aggressive ; afterward there is complete anaesthesia and loss of consciousness. It has been much used, by dentists especially, as an anaesthetic in operations of short dura- tion, and in one or two instances anaesthesia has been maintained by its use for nearly an hour. A solution in water under pressure, containing five volumes of the gas, is sometimes used for internal administration. 74 MANUAL OF CHEMISTRY. Nitrogen Dioxide. Nitric oxide—NO—Molecular weight = 30—Sp. gr. = 1.039H—Dis- covered by Hales in 1772. Preparation.—By the action of copper on moderately diluted nitric acid in the cold : 3Cu + 8HN03 = 3Cu(N03)„ +• 4H20 + 2NO ; the gas being collected after displacement of air from the apparatus. Properties.—A colorless gas, whose odor and taste are unknown ; very sparingly soluble in H,0 ; more soluble in alcohol. It combines with O when mixed with that gas or with air, to form the reddish-brown nitrogen tetroxide. It is absorbed by solution of ferrous sulphate, to which it communicates a dark brown or black color. It is neither combustible nor a good supporter of combustion, although ignited C and P continue to burn in it, and the alkaline metals, when heated in it, combine with its O with incandescence. Nitrogen Trioxide. Nitrous anhydride.—N,0:J—76. Has not been obtained in a condition of purity. A mixture of 95 per cent, of N„Oa with 5 per cent, of N,0 may, however, be obtained by decomposing liquefied nitrogen tetroxide with a small quantity of H.,0 at a low temperature : 4NO, + H,0 = 2HN03 4- N,0,. This is a dark indigo-blue liquid, which, boiling at about 0° (32° F.), is partly decom- posed. Nitrogen Tetroxide Nitrogen peroxide—Hyponitric acid—Nitrous fumes—NO,—Molec- idar weight = 46—Sp. gr. = 1.58A (at 154°(7.)—Boils at 22° (71°.6 F.) —Solidifies at 9° (15°.8 F.). Preparation.—(1.) By mixing one volume O with two volumes NO ; both dry and ice-cold. (2.) By heating perfectly drv lead nitrate, O being also produced : 2Pb(NOs)2 = 2PbO + 4N02 + 02. (3.) By dropping strong nitric acid upon a red-hot platinum surface. Properties.—When pure and dry it is an orange-yellow liquid at the ordinary temperature ; the color being darker the higher the temperature. The red fumes which are produced when nitric acid is decomposed by starch or by a metal consist of NO, mixed with N„03. It dissolves in nitric acid, forming a dark yellow liquid, which is blue or green if N,Oa be also present. With SO, it combines to form a solid, crystalline compound, which is sometimes produced in the manufacture of H,S04, and known as lead chamber crystals. A small quantity of H.,0 decomposes it into HNO, and N,03, which latter colors it green or blue ; a larger quantity of HO decomposes it into HN03 and NO. By bases it is transformed into a mixture of nitrite and nitrate: 2NO, + 2KHO = KNO, 4- IvN03 + H.,0. It is an energetic oxydant, for which it is largely used. With certain organic substances it does not behave as an oxydant, but becomes NITKOGEN ACIDS 75 substituted as an univalent radical; thus with benzol it forms nitro-benzol: C6H5(N02). Toxicology.—The brown fumes given off during many processes, in which nitric acid is decomposed, are dangerous to life. All such opera- tions, when carried on on a small scale, as in the laboratory, should be conducted under a hood or some other arrangement, by which the fumes are carried into the open air. When, in industrial processes, the volume of gas formed becomes such as to be a nuisance when discharged into the air, it should be utilized in the manufacture of H.,S04 or absorbed by H.,0 or an alkaline solution. An atmosphere contaminated with brown fumes is more dangerous than one containing Cl, as the presence of the latter is more immediately annoying. At first there is only coughing, and it is only two to four hours later that a difficulty in breathing is felt, death occurring in ten to fifteen hours. At the autopsy the lungs are found to be extensively disorganized and filled with black fluid. Even air containing small quantities of brown fumes, if breathed for a long time, produces chronic disease of the respiratory organs. To prevent such accidents, thorough ventilation in locations where brown fumes are liable to be formed is imperative. In cases of spilling nitric acid, safety is to be sought in retreat from the apartment until the fumes have been replaced by pure air from without. Nitrogen Pentoxide. Nitric anhydride—N,Or—Molecular weight = 108—Fuses at 30° (86° F.) —Boils at 47° (116°.G F). Preparation.—(1.) By decomposing dry silver nitrate with dry Cl in an apparatus entirely of glass: 4AgN03 + 2C1„ = 4AgCl 4- 2N,,Os -4- O.,. (2.) By removing water from fuming nitric acid with phosphorus pent- oxide : 6HN03 + PA = 2H3P04 + 3N206. Properties.—Prismatic crystals at temperatures above 30° (86° F.). It is very unstable, being decomposed by a heat of 50° (122° F.) ; on contact with H.,0, with which it forms nitric acid; and even spontaneously. Most substances which combine readily with O, remove that element from N.,0.. Nitrogen Acids. Three are known, either free or in combination, corresponding to the three oxides containing uneven numbers of O atoms: NnO + H,0 — 2HNO—Hyponitrous acid. NaOs + H„G — 2HNO.,—Nitrous acid. Na05 4- H,0 = 2HN03—Nitric acid. Hyponitrcms acid—HNO—31—Known only in combination. Silver hyponitrite is reduction of sodium nitrate by nascent H and de- composition with silver nitrate. Nitrous acid—HNO,2—47—has not been isolated, although its salts, the nitrites, are well-defined compounds: MNO, or M"(NOa)!i, MANUAL OF CHEMISTEY. Nitric Acid. Aquafortis—Hydrogen nitrate—Acidum nitricum—IT. S.; Br.—HNOs —63. Preparation.—(1.) By the direct union of its constituent elements under the influence of electric discharges. (2.) By the decomposition of an alkaline nitrate by strong H.SO,. With moderate heat a portion of the acid is liberated : 2NaNO.t + H2S04 = NaHS04 4- NaN03 + HN03, and at a higher temperature the remainder is given off: NaN03 + NaH8>04 = Na„S04 4- HNOa. This is the reaction used in the manufacture of HNOs. Varieties. — Commercial—a yellowish liquid, very impure, and of two degrees of concentration: single aquafortis; sp. gr. about 1.25 = 39$ HN03 ; and double aquafortis ; sp. gr. about 1.4 = 64$ HN03. Fuming—a reddish yellow liquid, more or less free from impurities ; charged with oxides of nitrogen. Sp. gr. about 1.5. Used as an oxidiz- ing agent. G. F.—a colorless liquid, sp. gr. 1.522, which should respond favorably to the tests given below. Acidum nitricum, U S. ; Br.—a colorless acid, of sp. gr. 1.42 = 70$ hno3. Acidum nitricum dilutum, U. S.; Br.—the last mentioned, diluted with H20 to sp. gr. 1.059 = 10$ HN03 (U. S.), or to sp. gr. 1.101 = 17.44$ HN03 (Br.). Properties.—Physical.—The pure acid is a colorless liquid ; sp. gr. 1.522 ; boils at 86° (186°.8 F.) ; solidities at—40° (—40° F.); gives off white fumes in damp air ; and has a strong acid taste and reaction. The sp. gr. and boiling-point of dilute acids vary with the concentration. If a strong acid be distilled, the boiling-point gradually rises from 86° (186°.8 F.) until it reaches 123° (253°.4 F.), when it remains constant, the sp. gr. of distilled and distillate being 1.42 = 70$ HNO . If a weak acid be taken originally the boiling-point rises until it becomes stationary at the same point. Chemical.—When exposed to air and light, or when heated to redness, HN03 is decomposed into NOa; H„0 and O. Nitric acid is a valuable oxydant; it converts I, P, S, C, B, and Si or their lower oxides into their highest oxides; it oxidizes and destroys most organic substances, although with some it forms products of substitution. Most of the metals dissolve in HNOa as nitrates, a portion of the acid being at the same time decomposed into NO and H,,0 : 4HNO., 4- 3Ag = 3AgNO,, + NO -f 2H„0. The so-called “noble metals,” gold and platinum, are not dissolved by either HN03 or HC1, but dissolve as chlorides in a mixture of the two acids, called aqua regia. In this mixture the two acids mutually decompose each other according to the equations : HNOa + 3HC1 = 2H.0 4- NOC1 + Cl, and 2HNOa + 6HC1 = 4H30 + 2NOC1, + Cl., with formation of nitrosyl chloride, NOC1, and bichloride NOC1,; and nascent Cl; the last named combining with the metal. When HN03 is decomposed by zinc or iron or in the porous cup of a Grove battery, N,Oa and NO., are formed and dissolve in the acid, which is colored dark yellow, blue or green. An acid so charged is known as nitroso-nitric acid. Nitric acid is monobasic. Impurities.— Oxides of Nitrogen render the acid yellow, and decolorize NITROGEN" CHLORIDE. potassium permanganate when added to the dilute acid. Sulphuric acid produces cloudiness when BaCl3 is added to the acid, diluted with two volumes of H O. Chlorine, iodine cause a white ppt. with AgN03. Iron gives a red color when the diluted acid is treated with ammonium sulplio- cyanate. Salts, leave a fixed residue when the acid is evaporated to dry- ness on platinum. Analytical Characters.—(1.) Add an equal volume of concentrated H.SO,, cool, and tioat on the surface of the mixture a solution of FeS04. The lower layer becomes gradually colored brown, black or purple, be- ginning at the top. (2.) Boil in a test-tube a small quantity of HC1 containing enough sulphindigotic acid to communicate a blue color, add the suspected solu- tion and boil again ; the color is discharged. (3.) If acid neutralize with KHO, evaporate to dryness, add to the res- idue a few drops of H..SO, and a crystal of brucine (or some sulphanilic acid) ; a red color is produced. (4.) Add H2S04 and Cu to the suspected liquid and boil, brown fumes appear (best visible by looking into the mouth of the test-tube). The above appearances are caused by free nitric acid, but if the tests be conducted as directed a nitrate, if present, is decomposed with libera- tion of the acid. All neutral nitrates are soluble in H.O ; some so-called basic salts are insoluble, as bismuthyl nitrate : (BiO)N03. Toxicology.—Although most of the nitrates are poisonous when taken internally in sufficiently large doses, their action seems to be due rather to the metal than to the acid radical. Nitric acid itself is one of the most powerful of corrosives. Any animal tissue with which the concentrated acid comes in contact is immediately disintegrated ; a yellow stain, afterward turning to dirty brownish, or, if the action be prolonged, an eschar, is formed. When taken internally its action is the same as upon the skin, but, owing to the more immediately important function of the parts, is followed by more serious results (unless a large cutaneous surface be destroyed). The symptoms following its ingestion are the same as those produced by the other mineral acids, except that all parts with which the acid has come in contact, including vomited shreds of mucous membrane, are colored yellow. The treatment is the same as that indicated when S04H3 or HC1 have been taken ; i.e. neutralization of the corrosive by magnesia or an alkali. Compounds of Nitrogen with the Halogens. Nitrogen chloride—NC13—120.5—is formed by the action of excess of Cl upon NH3 or an ammoniacal compound. It is an oily, light yellow liquid ; sp. gr. i.653 ; has been distilled at 71° (159°.8 F.). When heated to 96° (204°.8 F.), when subjected to concussion, or when brought in contact with phosphorus, alkalies or greasy matters it is decomposed, with a violent explosion, into one volume N and three volumes Cl. Nitrogen bromide—NBr1—254—has been obtained as a reddish brown, syrupy liquid, very volatile, and resembling the chloride in its properties, by the action of potassium bromide upon nitrogen chloride. Nitrogen iodide—NI,—395—When iodine is brought in contact with ammonium hydrate solution, a dark brown or black powder, highly 78 MANUAL OF CHEMISTRY. explosive when dried, is formed. This substance varies in composition according to the conditions under which the action occurs ; sometimes the iodide alone is formed ; under other circumstances it is mixed with conqpounds containing N, I and H. PHOSPHORUS. Symbol — P—Atomic weight — 31—Molecular weight — 124—Sp. gr. of vapor = 4.2904 A—Name from tos = light, rehended from the tendency of repeated small doses of Rochelle salt to render the urine alkaline and thus favor the formation of phospliatic calculi, than from any supposed deleterious action of alumina, whose local action, even in considerable doses, is that of a very mild astringent, and whose ab- sorption is very doubtful. Sodium Potassium Tartrate—Rochelle salt—Sel de seignette—Potassii et sodii tartras (U. S.)—Soda tartarata (Br.)—NaKC4H406 + 4Aq—210 + 72 —is prepared by saturating hydropotassic tartrate with sodium carbonate. It crystallizes in large, transparent prisms, which effloresce superficially in dry air and attract moisture in damp air. It fuses at 70-80° (158°-i76° F.), and loses 3 Aq at 100° (212° F.). It is soluble in H,0. the solutions being dextrogyrous, [a]D = +29°.67. SALTS OF POTASSIUM. 141 Potassium Antimonyl Tartrate—Tarlarated antimony—Tartar emetic— Antimonii et potassii tartras (U. S.)—Antimonium tartaratum (Br.)—(SbO)‘ KC1H4Ob—323—is prepared by boiling a mixture of 3 pts. Sb.,03 and 4 pts. HKC4H40B in H,0 for an hour, filtering, and allowing to crystallize ; when required pure, it must be made from pure materials. It crystallizes in transparent, soluble, right rhombic octahedra, which turn white in air. Its solutions are acid in reaction, have a nauseating, metallic taste, are leevogyrous, [a]D = +156°.2, and are precipitated by alcohol. The crystals contain £ Aq, which they lose entirely at 100° (212= F.), and partially by exposure to air. It is decomposed by the alkalies, alkaline earths, and alkaline carbonates, with precipitation of Sba03. The precipitate is redissolved by excess of soda or potash, or by tartaric acid. HC1, H,SO, and HN03 precipitate corresponding antimonyl compounds from solutions of tartar emetic. It converts mercuric into mercurous chloride. It forms double tartrates with the tartrates of the alkaloids. Potassium Cyanide—Potassii cyanidum (U. S.)—KCN—65—is ob- tained by heating a mixture of potassium ferrocyanide and dry K2C03 as long as effervescence continues ; decanting and crystallizing. It is usually met with in dull, white, amorphous masses ; odorless when dry, it has the odor of hydrocyanic acid when moist. It is deliques- cent, and very soluble in H20 ; almost insoluble in alcohol. Its solution is acrid, and bitter in taste, with an after-taste of hydrocyanic acid. It is very readily oxidized to the cyanate, a property which renders it valuable as a reducing agent. Solutions of KCN dissolve I, AgCl, the cyanides of Ag and Au, and many metallic oxides. It is actively poisonous, and produces its effects by decomposition and liberation of hydrocyanic acid (q. i\). Potassium Ferrocyanide—Yellow prussiate of potash—Potassii fer- rocyanidum (U. S.)—Potassceprussias flava (Br.)—K.[Fe(CN)J -f 3 Aq— 367.9 + 54.—This salt, the source of the other cyanogen compounds, is manufactured by adding organic matter (blood, bones, hoofs, leather, etc.) and iron to K.2C03 in fusion ; or by other processes in which the N is ob- tained from the residues of the purification of coal-gas, from atmospheric air, or from ammoniacal compounds. It forms soft, flexible, lemon-yellow crystals, permanent in air at ordi- nary temperatures. They begin to lose Aq at 60° (140° F.), and become anhydrous at 100° (2123 F.). Soluble in H,0 ; insoluble in alcohol, which precipitates it from its aqueous solution. When calcined with KHO or K,C03, potassium cyanide and cyanate are formed, and Fe is precipitated. Heated with dilute H.,S04, it yields an insoluble white or blue salt, potas- sium sulphate, and hydrocyanic acid. Its solutions form with those of many of the metallic salts insoluble ferrocyanides ; those of Zn, Pb, and Ag are white, cupric ferrocyanide is mahogany-colored, ferrous ferrocyanide is bluish-white, ferric ferrocyanide (Prussian blue) is dark blue. Blue ink is a solution of Prussian blue in a solution of oxalic acid. Potassium Ferricyanide—Pled prussiate of potash—K(.Fe2(CN)12— 657.8—is prepared by acting upon the ferrocyanide with chlorine ; or, better, by heating the white residue of the action of H.,S04 upon potassium ferrocyanide, in the preparation of hydrocyanic acid, with a mixture of 1 vol. HN03 and 20 vols. H,0 ; the blue product is digested with H20 and potassium ferrocyanide, the solution filtered and evaporated. It forms red, oblique, rhombic prisms, almost insoluble in alcohol. With solutions of ferrous salts it gives a dark blue precipitate, Turnbull's blue. 142 MANUAL OF CHEMISTRY. Analytical Characters. (1.) Platinic chloride, in presence of IICl : yellow ppt.; crystalline if slowly formed ; sparingly soluble in H20, much less so in alcohol. (2.) Tartaric acid, in not too dilute solution : white ppt.; soluble in al- kalies and in concentrated acids. (3.) Hydrohuosilicic acid : translucent, gelatinous ppt.; forms slowly; soluble in strong alkalies. (4.) Perchloric acid : white ppt.; sparingly soluble in 11,0 ; insoluble in alcohol. (5.) Phosphomolybdic acid : white ppt.; forms slowly. (6.) Colors the Bunsen flame violet (the color is only observable through blue glass in presence of Na). and exhibits a spectrum of two bright lines : A — 7860 and 4045 (Fig. 14, No 3). Action of the Sodium and Potassium Compounds on the Economy. The hydrates of Na and of K, and in a less degree the carbonates, dis- integrate animal tissues, dead or living, with which they come in contact, and, by virtue of this action, act as powerful caustics upon a living tissue. Upon the skin they produce a soapy feeling and in the mouth a soapy taste. Like the acids, they cause death, either immediately, by corrosion or perforation of the stomach ; or secondarily after weeks or months, by closure of one or both openings of the stomach, due to thickening, conse- quent upon inflammation. The treatment consists in the neutralization of the alkali by an acid, dilute vinegar. Neutral oils and milk are of service, more by reason of their emollient action than for any power they have to neutralize the alkali by the formation of a soap at the temperature of the body. The other compounds of Na, if the acid be not poisonous, are without deleterious action, unless taken in excessive quantity. Common salt has produced paralysis and death in a dose of half a pound. The neutral salts of K, on the contrary, are by no means without true poisonous action when taken internally, or injected subcutaneously in sufficient quantities ; causing dyspnoea, convulsions, arrest of the heart’s action, and death. In the adult human subject, death has followed the ingestion of doses of 3 ss. - 3 j. of the nitrate, in several instances ; doses of 3 ij- — 3 ij. of the sul- phate have also proved fatal. Caesium—Symbol = Cs—Atomic weight = 132.6; and Rubidium—Symbol = Rb—Atomic weight = 86.3 —are two rare elements, discovered in 1860 by Kirchoff and Bunsen while examining spectroscopically the ash of a spring water. They exist in very small quantity in lepidolxte. They combine with O amt decom- pose H20 even more energetically than does K, forming strongly alkaline hydrates. SILVER. Symbol = Ag (ARGENTUM )—Atomic vwiqh* — 107.0 — Molecular weight = 216 (?)—Sp. gr. = 10.4-10.54—Fuses at 1,000° (1,832° F.). Although silver is usually classed with the “ noble metals,” it differs from Au and Pt widely in its chemical characters, in which it more closely resembles the alkaline metals. ANALYTICAL CHARACTERS. 143 When pure Ag is required, coin silver is dissolved in HX03 and the di- luted solution precipitated with HC1. The silver chloride is washed until the washings no longer precipitate with silver nitrate ; and reduced either (1) by suspending it in dilute H.,S04 in a platinum basin, with a bar of pure Zn, and washing thoroughly after complete reduction ; or (2) by mix- ing it with chalk and charcoal (AgCl, 100 parts ; C, 5 parts ; CaC03, 70 parts) and gradually introducing the mixture into a red-hot crucible. Silver is a white metal; very malleable and ductile ; the best known conductor of heat and electricity. It is not acted on by pure air, but is blackened in air containing a trace of H.,S. It combines directly with Cl, Br, I, S, P, and As. Hot H„S04 dissolves it as sulphate, and HN03 as nitrate. The caustic alkalies do not affect it. It alloys readily with many metals : its alloy with Cu is harder than the pure metal. Oxides.—Three oxides of silver are known : Ag(0, Ag.O, and Ag,0 ... Silver Monoxide—Protoxide—Argenti oxidum—(U. S.; Br.)—Ag O— 231.8—formed by precipitating a solution of silver nitrate with potash. It is a brownish powder ; faintly alkaline and very slightly soluble in HO; strongly basic. It readily gives up its oxygen. On contact with ammo- nium hydrate it forms a fulminating powder. Chloride—AgCl—143.4—formed when HC1 or a chloride is added to a solution containing silver. It is white ; turns violet and black in sun- light ; volatilizes at 260° (500° F.); sparingly soluble in HC1; soluble in solutions of the alkaline chlorides, hyposulphides, and cyanides, and in am- monium hydrate. Bromide—AgBr; and Iodide—Agl—are yellowish precipitates, formed by decomposing silver nitrate with potassium bromide and iodide. Argentic Nitrate—Argenti nitras (U. S.; Br.)—AgN03—169.9—is prepared by dissolving Ag in HN03, evaporating, fusing, and recrystalliz- ing. It crystallizes in anhydrous, right rhombic plates ; soluble in H.,0. The solutions are colorless and neutral, In the presence of organic matter it turns black in sunlight. The salt, fused and cast into cylindrical moulds, constitutes lunar caus- tic, lapis infernalis ; argenti nitras fusa (U. S.). If, during fusion, the tem- perature be raised too high, it is converted into nitrite, O, and Ag ; and if sufficiently heated leaves pure Ag. Dry Cl and I decompose it, with liberation of anhydrous IIN03. It absorbs NH;, to form a white solid, AgN03,3NH3, which gives up its NII3 when heated. Its solution is decomposed very slowly by H, with deposi- tion of Ag. Argentic Cyanide—Argenti cyanidum (U. S.)—AgCN—133.9—is prepared by passing HCN through a solution of AgN03. It is a white, tasteless powder ; gradually turns brown in daylight ; insoluble in dilute acids ; soluble in ammonium hydrate, and in solutions of ammoniacal salts, cyanides, or hyposulphites. The strong mineral acids decompose it with liberation of HCN. Analytical Characters (1.) Hydrochloric acid : white, flocculent ppt. ; soluble in NH4HO; insoluble in HN03. (2.) Potash or soda : brown ppt, ; insoluble in excess ; soluble in NH4 HO. (3.) Ammonium hydrate, from neutral solutions : brown ppt. ; soluble in excess. 144 MANUAL OF CHEMISTRY. (4.) Hydrogen sulphide or ammonium sulpliydrate : black ppt. ; in- soluble in NHHS. (5.) Potassium bromide : yellowisli-white ppt. ; insoluble in acids, if not in great excess ; soluble in NH HO. (6.) Potassium iodide : same as KBr, but the ppt. is less soluble in NHHO. Action on the Economy. Silver nitrate acts both locally as a corrosive, and systemically as a true poison. Its local action is due to its decomposition by contact with organic substances, resulting in the separation of elementary Ag, -whose deposition causes a black stain, and liberation of free HNOa, which acts as a caustic. When absorbed, it causes nervous symptoms, referable to its poisonous action. The blue coloration of the skin, observed in those to whom it is administered for some time, is due to the reduction of the metal under the combined influence of light and organic matter ; especially of the latter, as the darkening is observed, although it is less intense, in internal organs. In acute poisoning by silver nitrate, sodium chloride or white of egg should be given; and, if the case be seen before the symptoms of corrosion are far advanced, emetics. AMMONIUM COMPOUNDS. The ammonium theory.—Although the radical ammonium, NH(, has probably never been isolated, its existence in the ammoniacal com- pounds is almost universally admitted. The ammonium hypothesis is based upon the following facts: (1) the close resemblance of the ammoni- acal salts to those of K and Na ; (2) when ammonia gas and an acid gas come together, they unite, without liberation of hydrogen, to form an am- moniacal salt; (3) the diatomic anhydrides unite directly with dry am- monia with formation of the ammonium salt of an amido acid : SO, + 2NH, = SO,(NH2)(NH4) (4) when solutions of the ammoniacal salts are subjected to electrolysis, a mixture having the composition NH3 + H is given off at the negative pole ; (5) amalgam of sodium, in contact with a concentrated solution of am- monium cliloride, increases much in volume, and is converted into a light, soft mass, having the lustre of mercury. This ammonium amalgam is de- composed gradually, giviug off ammonia and hydrogen in the proportion NH3 + H; (6) if the gases NH3 4- H, given off by decomposition of the amalgam, exist there in simple solution, the liberated H would have the ordinary properties of that element; if, on the other hand, they exist in combination, the H would exhibit the more energetic affinities of an ele- ment in the nascent state. The hydrogen so liberated is in the nascent state. Sulphur trioxide. Ammonia. Ammonium sulphamate. Compounds of Ammonium Ammonium Hydrate—Caustic ammonia—NHHO—35—lias never been isolated, probably owing to its tendency to decomposition: NH HO = NH3 + H ,0. It is considered as existing in the so-called aqueous solutions SALTS OF AMMONIUM. 145 of ammonia. These are colorless liquids ; of less sp. gr. than H.,0 ; strongly alkaline ; and having the taste and odor of ammonia, which gas they give off on exposure to air, and more rapidly when heated. They are neutralized by acids, with elevation of temperature and formation of ammoniacal salts. The Aqua ammonice (U. S.) and Liq. Ammoniae (Br.) are such solutions. Su phides.—Four are known : (NH4).,S ; (NH1),4Sa ; (NH VS4 ; and (NH,).,S. ; as well as a sulphydrate (NH^HS. Ammonium Sulphydrate—NH4H:—51—is formed in solution by satu- rating a solution of NH4HO with H ,S; or anhydrous by mixing equal volumes of dry NH3 and dry H ,S. The anhydrous compound is a colorless, transparent, volatile and soluble solid ; capable of sublimation without decomposition. The solution when freshly prepared is colorless, but soon becomes yellow from oxidation and formation of ammonium disulphide and hyposulphite, and finally de- posits sulphur. The sulphides and hydrosulphide of ammonium are also formed during the decomposition of albuminoids, and exist in the gases formed in burial vaults, sewers, etc. Ammonium Chloride—Sal ammoniac—Ammonii chloridum (U.S.; Br.)—NH4C1—53.5—is obtained from the ammoniacal water of gas- works. It is a translucid, fibrous, elastic solid ; salty in taste, neutral in reaction ; volatile without fusion or decomposition ; soluble in HaO. Its solution is neutral, but loses NH.. and becomes acid when boiled. Ammonium chloride exists in small quantity in the gastric juice of the sheep and dog ; also in the perspiration, urine, saliva, and tears. Ammonium Bromide—Ammonii bromidum (II. S.)—(NHjBr—98 —is formed either by combining NH3 and HBr ; by decomposing ferrous bromide with NH4HO ; or by double decomposition between KBr and S04 (NH4)a. It is a white, granular powder, or crystallizes in large prisms, which turn yellow on exposure to air ; quite soluble in H30 ; volatile with- out decomposition. Ammonium Iodide—Ammonii iodidum (U. S.)—NH4I — 145 — is formed by union of equal volumes of NH3 and HI; or by double decom- position of KI and (NH1).,S01. It crystallizes in deliquescent, soluble cubes. Salts of Ammonium. Ammonium Nitrate—Ammonii nitras (U. S.)—(NH)N03—80—is prepared by neutralizing HNO.( with ammonium hydrate or carbonate. It crystallizes in flexible, anhydrous, six-sided prisms ; very soluble in H20 with considerable diminution of temperature ; fuses at 150° (302° F.), and decomposes at 210° (410° F.), with formation of.nitrous oxide : (NH4)N03 = N20 + 2 H,0. If the heat be suddenly applied or allowed to surpass 250° (482° F.), NH3, NO, and NaO are formed. When fused it is an active oxidant. Sulphates—Ammonic Sulphate—Diammonic sulphate—Ammonii sul- phas (U. S.)—(NH4),SO 4—132—is obtained by collecting the distillate from a mixture of ammoniacal gas liquor and lime in H SO 4. It forms anhydrous, soluble, rhombic crystals ; fuses at 140° (284° F.), and is decomposed at 200° (392° F.) into NH3 and H (NH4)S04. Hydroammonic Sulphate—Mono-ammonic sulphate—Bisulphate of ammo- nia—H(NH)4S04—115—is formed by the action of H,S04 on (NH4)aS04. It crystallizes in right rhombic prisms, soluble in H40 and alcohol. 146 MANUAL OF CHEMISTRY. Ammonium Acetate— (NH,)C,H;0. —77—is formed by saturating acetic acid with NH3, or with ammonium carbonate. It is a white, odor- less, very soluble solid ; fuses at 86° (186°.8 F.), and gives off NH3 ; then acetic acid, and finally acetamide. Liq. ammonii acetatis — Spirit of Min- dererus is an aqueous solution of this salt. Carbonates.—Ammonic Carbonate—Diammonic carbonate—Neutral am- monium carbonate— (NH4)3COf + Aq —96 4- 18—has been obtained as a white crystalline solid. In air it is rapidly decomposed into NH and H(NH4)C03. Hydro ammonic Carbonate — Monoammonic carbonate—Acid carbonate of ammonia— H(NH4)CO — 79 —is prepared by saturating a solution of NHHO or ammonium sesquicarbonate with C02. It crystallizes in large, rhombic prisms ; quite soluble in H„0. At 60° (140° F.) it is decomposed into NH3 and C02. Ammonium Sesquicarbonate—Sal volatile—Preston salts—Ammonii car- bonas. (U. S.)—Ammonice carbonas (Br.)—(NH4)4H„(C03)3—254—is pre- pared by heating a mixture of NH C1 and chalk, and condensing the pro- duct. It crystallizes in rhombic prisms ; has an ammoniacal odor and an alkaline reaction ; soluble in H.,0. By exposure to air or by heating its solution it is decomposed into H„0, NH3, and H(NH4)C03. Analytical Characters. (1.) Entirely volatile at high temperatures. (2.) Heated with KHO, the ammoniacal compounds give off NH.„ re- cognizable : (a) by changing moist red litmus to blue ; (b) by its odor ; (c) by forming a white cloud on contact with a glass rod moistened with ilCl. (3.) With platinic chloride : a yellow, crystalline ppt. (4.) With hydro-sodic tartrate, in moderately concentrated and neutral solution : a white, crystalline ppt. Action on the Economy. Solutions of the hydrate and carbonate act upon animal tissues in the same way as the corresponding Na and K compounds. They, moreover, disengage NH3, which causes intense dyspnoea, irritation of the air pas- sages, and suffocation. The treatment indicated is the neutralization of the alkali by a dilute acid. Usually the vapor of acetic acid or of dilute HC1 must be adminis- tered by inhalation. n. THALLIUM GBOUP. THALLIUM Symbol = T1—Atomic weight — 203.7 — tip. gr. = 11.8-11.9—Fuses at 294° (561° F.)—Discovered by Crookes (1861). A rare element, first obtained from the deposits in flues of sulphuric acid factories, in which pyrites from the Hartz were used. It resembles Pb in appearance and in physical properties, but differs entirely from that element in its chemical characters. It resembles Au in being univalent and trivalent, but differs from it, and resembles the alkaline metals in being readily' oxidized, in forming alums, and in forming no acid hydrate. It differs from the alkaline metals in the thallic compounds, which contain TP". It is character- ized spectroscopically by a bright green line—A = 5349. COMPOUNDS OF CALCIUM. 147 m. CALCIUM GROUP. Metals of the Alkaline Earths. Calcium—Strontium—Barium. The members of this group are bivalent in all their compounds ; each forms two oxides : MO and MO. ; each forms a hydrate having well- marked basic characters. CALCIUM. Symbol = Ca—Atomic weight = 40—Molecular weight — 80 (?)—Sp. gr. = 1.984—Discovered by Davy in 1808—Name from calx = lime. Occurs only in combination, as limestone, marble, chalk (CaC03) ; gypsum, selenite, alabaster (CaS04), and many other minerals. In bones, egg-shells, oyster-shells, etc., as Ca3(P04)3 and CaC03, and in many vegetable structures. The element is a hard, yellow, very ductile, and malleable metal; fusi- ble at a red heat; not sensibly volatile. In dry air it is not altered, but is converted into CaH.,0., in damp air ; decomposes H20; bums when heated in air. Compounds of Calcium Calcium Monoxide—Quick lime—Lime—Calx (U. S.; Br.)—CaO— 56—is prepared by heating a native carbonate (limestone) ; or, when re- quired pure, by heating a carbonate prepared by precipitation. It occurs in white or grayish, amorphous masses ; odorless ; alkaline ; caustic ; almost infusible ; sp. gr. 2.3. With H.,0 it gives off great heat and is converted into the hydrate (slacking). In air it becomes air-slacked, falling into a white powder, having the composition CaC03, CaH202. Calcium Hydrate—Slacked lime—Calais hydras (Br.)—CaH02—74 —is formed by the action of H„0 on CaO. If the quantity of H„0 used be one-third that of the oxide, the hydrate remains as a dry, white, odorless powder; alkaline in taste and reaction ; more soluble in cold than in hot H.O. If the quantity of H,,0 be greater a creamy or milky liquid remains, cream or milk of lime ; a solution holding an excess in suspension. With a sufficient quantity of H„0 the hydrate is dissolved to a clear solution, which is lime water—Liquor calcis (U. S. ; Br.). The solubility of CaH.O., is diminished by the presence of alkalies, and is increased by sugar or mannite : Liq. calc, saccharatus (Br.). Solutions of CaH.,0. absorb C02 with formation of a white deposit of CaCO„. Calcium Chloride—Calcii chloridum (U. S.; Br.)—CaCl.,—111—is obtained by dissolving marble in HC1 : CaC03 -f- 2HC1 = CaCl., -I- H.,0 + C02. It is bitter ; deliquescent; very soluble in H.,0 ; crystallizes with 6 Aq, which it loses when fused, leaving a white, amorphous mass; used as a drying agent. Chloride of Lime—Bleaching powder—Calx chlorala (V. S. ; Br.)—is a mixture composed chiefly of CaCl., and calcium hypochlorite Ca(C10)„; pre- pared by passing Cl over CaH.O., maintained in excess. It is a grayish 148 MANUAL OF CHEMISTRY. white powTder ; bitter and acrid in taste ; soluble in cold H20 ; decomposed by boiling H.,0, and by the weakest acids with liberation of Cl. It is de- composed by C02 with formation of CaC03, and liberation of liypochlorous acid, if it be moist; or of Cl, if it be dry. A valuable disinfectant. Salts of Calcium. Calcium Sulphate—CaS04—136—occurs in nature as anhydrite, and with 2 Aq in gypsum, alabaster, selenite; and in solution in natural waters. Terra alba is ground gypsum. It crystallizes with 2 Aq in right rhombic prisms ; sparingly soluble in H.,0, more soluble in H.,0 containing free acid or chlorides. When the hydrated salt (gypsum) is heated to 80 J (176° F.), or more rapidly between 120°-130° (248°-2G6° F.), it loses its Aq and is converted into a white, opaque mass ; which, when ground, is plaster-of-Paris. The setting of plaster when mixed with H20, is due to the conversion of the anhydrous into the crystalline, hydrated salt. The ordinary plastering should never be used in hospitals, as, by reason of its irregularities and porosity it soon becomes saturated with the transferrers of septic disease, be they germs or poisons, and cannot be thoroughly purified by disinfect- ants. Plaster surfaces may, however, be rendered dense and be highly polished, so as to be smooth and impermeable, by adding glue and alum, or an alkaline silicate to the water used in mixing. Phosphates.—Three are known : Ca3(P04)2; Ca2(HP04)2, and Ca(H2 P04)2. Tricalcic Phosphate—Tribasic or neutral phosphate—Bone phosphate— Calcii phosphas prcecipitatus (U. S.)—Calcis phosphas (Br.)—Ca.(PO),,— 310—occurs in nature in soils, guano, coprolites, phosphorite, in all plants, and in every animal tissue and fluid. It is obtained by dissolving bone-ash in HC1, filtering, and precipitating with NH4HO; or by double decomposi- tion between CaCl2 and an alkaline phosphate. When freshly precipitated it is gelatinous; when dry, a light, white, amorphous powder ; almost in- soluble in pure H20; soluble to a slight extent in H,,0 containing am- moniacal salts, or NaCl or NaNOa; readily soluble in dilute acids, even in H. charged with carbonic acid. It is decomposed by H2S04 into CaS04 and Ca(H,P04)2. Bone-ash is an impure form of Ca3(P04)2, obtained by calcining bones, and used in the manufacture of P and of superphosphate. Dicalcic Phosphate—Ca(HPO)2 + 2 Aq—272 + 36—is a crystalline, insoluble salt; formed by double decomposition between CaCl., and HNa, PO , in acid solution. Monocalcic Phosphate—Acid calcium phosphate—Superphosphate 2 £ B H eg a 2 XL U 1 >» 5 r— fil o pi e 1 c o -3 5s fa's 8 a « ” cS > The teeth consist largely of Cas(P04),; the dentine of human molars containing G6.72 per cent., and the enamel 89.82 per cent. From the urine, tricalcic phosphate is frequently deposited, either in the form of an amorphous, granular sediment, or as calculi. The dicalcic salt occurs occasionally in urinary sediments, in the form of needle- shaped crystals arranged in rosettes, and also in urinary calculi. The mo){ocalcic salt is always present in acid urine, constituting, wTith the cor- responding magnesium salt, the earthy jdiosphates. The total elimination of H3P04 by the urine is about 2.75 grams (42.5 grains) in 24 hours; of which two-thirds are in combination with Na and K ; and one-third with Ca and Mg. The hourly elimination follows about the same variation as that of the chlorides. The total elimination is greater with animal than with vegetable food; is diminished during pregnancy; and is above the normal during excessive mental work. The elimination of earthy phos- phates is greatly increased in osteomalacia, often so far that they are in excess of the alkaline phosphates. So long as the urine is acid, it contains the soluble acid phosphates; when the reaction becomes alkaline, or even on loss of CO., by exposure to air, the acid phosphate is converted into the insoluble Cas(P04)3. Alkaline urines are for this reason almost always turbid, and become clear on the addition of acid. It is in such urine that phosphatic calculi are invariably formed, usually about a nucleus of uric acid or of a foreign body. If the alkalinity be due to the formation of ammonia, the trimagnesic phosphate is not formed, but ammonio-magnesian phosphate (q. v.). Quantitative determination of phosphates in urine.—A process for deter- mining the quantity of phosphates in urine is based upon the formation of the insoluble uranium phosphate, and upon the production of a 150 MANUAL OF CHEMISTRY. brown color when a solution of a uranium salt is brought in con- tact with a solution of potassium ferrocyanide. Four solutions are re- quired : (1) a standard solution of disodic phosphate, made by dissolving 10.085 grams of crystallized, non-effloresced HNa2P04 in H,0, and diluting to a litre ; (2) an acid solution of sodium acetate, made by dissolving 100 grams sodium acetate in H.O, adding 100 c.c. glacial acetic acid, and diluting with H,,0 to a litre ; (3) a strong solution of potassium ferrocy- anide ; (1) a standard solution of uranium acetate, made by dissolving 20.3 grams of yellow uranic oxide in glacial acetic acid, and diluting with HO to nearly a litre. Solution 1 serves to determine the true strength of tliis solution, as follows: 50 c.c. of Solution 1 are placed in a beaker, 5 c.c. of Solution 2 are added, the mixture heated on a water-bath, and the uranium solution gradually added from a burette until a drop from the beaker pro- duces a brown color when brought in contact with a drop of the ferrocy- anide solution. At this point the reading of the burette, which indicates the number of c c. of the uranium solution, corresponding to 0.1—P,05, is taken. A quantity of H20, determined by calculation from the result thus obtained, is then added to the remaining uranium solution, such as to render each c.c. equivalent to 0.005 gram P205. To determine the total phosphates in a urine: 50 c.c. are placed in a beaker, 5 c.c. sodium acetate solution are added ; the mixture is heated on the water-bath, and the uranium solution delivered from a burette until a drop, removed from the beaker and brought in contact with a drop of ferrocyanide solution, produces a brown tinge. The burette reading, multiplied by 0.005, gives the amount of P206 in 50 c. c urine; and this, multiplied by the amount of urine passed in 24 hours, gives the daily elimination. To determine the earthy phosphates, a sample of 100 c.c. urine is ren- dered alkaline with NH4HO and get aside for 12 hours ; the precipitate is then collected upon a filter, washed with ammoniacal water, brought into a beaker, dissolved in a small quantity of acetic acid ; the solution diluted to 50 c.c. with H20, treated with 5 c.c. sodium acetate solution, and the amount of P„Or) determined as above. Calcium Carbonate—CaC03—100—the most abundant of the natural compounds of Ca, exists as limestone, calcspar, chalk, marble, Ice- land spar, and arragonite ; and forms the basis of corals, shells of Crustacea and of molluscs, etc. The precipitated chalk—Calcii carbonas praecipitata (U. S. ; Br.)—is pre- pared by precipitating a solution of CaCl2 with one of Na2COs. Prepared chalk—Greta prceparata (U. S. ; Br.)—is native chalk, purified by grinding with H(0, diluting, allowing the coarser particles to subside, decanting the still turbid liquid, collecting, and drying the finer particles; a process known as elutriation. It is a white powder, almost insoluble in pure H„0 ; much more soluble in H.,0 containing carbonic acid, the solution being regarded as containing hydrocalcic carbonate H,Ca(CO,,)„. At a red heat it yields C02 and CaO. It is decomposed by acids with liberation of CO,. Physiological.—Calcium carbonate is much more abundant in the lowrer than in the higher forms of animal life. It occurs in the egg-shells of birds, in the bones and teeth of all animals ; in solution in the saliva and urine of the lierbivora, and deposited in the crystalline form, as otoliths, in the internal ear of man. It is deposited pathologically in calcifications, in parotid calculi, and occasionally in human urinary calculi and sediments. Calcium Oxalate — Oxalate of lime—CaC204—128—exists in the BARIUM. 151 sap of many plants, and is formed as a white, crystalline precipitate, by double decomposition between a Ca salt and an alkaline oxalate. It is in- soluble in H.,0, acetic acid, or NH(HO ; soluble in the mineral acids and in solution of H,,NaP04. Physiological.—Calcium oxalate is taken into the body in vegetable food, and is formed in the economy, where its production is intimately connected with that of uric acid. It occurs in the urine, in which it is increased in quantity when large amounts of vegetable food are taken; when sparkling wines or beers are indulged in ; and when the carbonates of the alkalies, lime-water and lemon-juice, are administered. It is deposited as a urinary sediment in the form of small, brilliant octahedra, having the appearance of the backs of square letter-envelopes ; or in dumb-bells. It is usually deposited from acid urine, and accompanied by crystals of uric acid. Sometimes, how- ever, it occurs in urines undergoing alkaline fermentation, in which case it is accompanied by crystals of ammonio-magnesian phosphate. The renal or vesical calculi of calcium oxalate, known as mulberry cal- culi, are dark brown or gray, very hard, occasionally smooth, generally tuberculated, soluble in HC1 without effervescence ; and when ignited, they blacken, turn white, and leave an alkaline residue. Analytical Characters. (1.) Ammonium sulphydrate : nothing, unless the Ca salt be the phos- phate, oxalate or fluoride, when it forms a white ppt. (2.) Alkaline carbonates : white ppt. ; not prevented by the presence of ammoniacal salts. (3.) Ammonium oxalate : white ppt. ; insoluble in acetic acid ; soluble in HC1, or IINO,. (4.) Sulphuric acid: white ppt., from solutions which are not too dilute ; very sparingly soluble in H.,0 ; insoluble in alcohol; soluble in sodium hyposulphite solution. (5.) Sodium tungstate : dense white ppt., even from dilute solutions. (6.) Colors the flame of the Bunsen burner reddish-yellow, and exhib- its a spectrum of a number of bright bands, the most prominent of which are : A = 6265, 6202, 6181, 6044, 5982, 5933, 5543, and 5517. STRONTIUM. Symbol = St—Atomic weight = 87.4—Sp. gr. — 2.54. An element, not as abundant as Ba, occurring principally in the minerals strontianite (C03Sr) and celes- tine (S04Sr). Its compounds resemble those of Ca and Ba. Its nitrate is used in making red fire. Analytical characters.—(1.) Behaves like Ba with alkaline carbonates and P04Na2H. (2.) Calcium sul- phate : a white ppt. which forms slowly ; accelerated by addition of alcohol. (3.) The Sr compounds color the Bunsen flame red, or, as observed through blue glass, purple or rose color. The Sr flame gives a spec- trum of many bands, of which the most prominent are : A = 6694, 6664, 6059, 6031, 4607. BARIUM. Symbol = Ba—Atomic weight = 136.8—Molecular weight — 273.6 (?)— Sp. gr. = 4.0—Discovered by Davy, 1808—Name from (3apvs = heavy. Occurs only in combination, principally as heavy spar (BaS04) and witherite (BaC03). It is a pale yellow, malleable metal, quickly oxidized in air, and decomposing H20 at ordinary temperatures. 152 MANUAL OF CHEMISTRY. Compounds of Barium Oxides.—Barium Monoxide—BaO—152.8—is prepared by calcining the nitrate. It is a grayish-white or white, amorphous, caustic solid. In air it absorbs moisture and C02, and combines with H ,0 as does CaO. Barium Dioxide—Ba02—168.8—is prepared by heating the monoxide in 0. It is a grayish-white, amorphous solid. Heated in air it is decom- posed : Ba02 = BaO + O. Aqueous acids dissolve it with formation of a barytic salt and H,02. Barium Monohydrate—Caustic baryta—BaH.,02—170.8—isprepared by the action of H.,0 on BaO. It is a white, amorphous solid, soluble in H20. Its aqueous solution, baryta water, is alkaline, and absorbs C02 with formation of a white deposit of BaC03. Barium Chloride—BaCl2 + Aq—207.8 + 36—is obtained by treat- ing BaS or BaC03 with HC1. It crystallizes in prismatic plates, perma- nent in air, soluble in H20. Salts of Barium. Barium Nitrate—Ba(N03)2 —260.8—is prepared by neutralizing HN03 with BaC03. It forms octahedral crystals, soluble in H20. Barium Sulphate—BaSOi—232.8—occurs in nature as heavy spar and is formed as an amorphous, white powder, insoluble in acids, by double decomposition between a Ba salt and a sulphate in solution. It is insoluble in H20 and in acids. It is used as a pigment, permanent ivhite. Barium Carbonate—BaC03—196.8—occurs in nature as witherite, and is formed by double decomposition between a Ba salt and a carbonate in alkaline solution. It is a heavy, amorphous, white powder, insoluble in H. O, soluble with effervescence in acids. Analytical Characters. (1.) Alkaline carbonates: white ppt.,in alkaline solution. .(2.) Sulphuric acid, or calcium sulphate: white ppt.; insoluble in acids. (3.) Sodium phosphate: white ppt.; soluble in HNOs. (4.) Colors the Bunsen flame greenish-yellow, and exhibits a spectrum of several lines, the most prominent of which are: A. = G108, 6044, 5881, 5536. Action on the Economy. The oxides and hydrate act as corrosives by virtue of then- alkalinity, and also as true poisons. All soluble compounds of Ba, and those which are readily converted into soluble compounds in the stomach, are actively poisonous. Soluble sulphates, followed by emetics, are indicated as anti- dotes. IV. MAGNESIUM GROUP. Magnesium—Zinc—Cadmium. Each of these elements forms a single oxide—a corresponding basic hy- drate, and a series of salts in which its atoms are bivalent. SALTS OF MAGNESIUM. 153 MAGNESIUM Symbol = Mg—Atomic weight = 24—Molecidar weight = 48 (?)—Sp. gr. = 1.75—Fuses at 1000° (1832° F.)—Discovered by Davy, 1808. Occurs as carbonate in dolomite or magnesian limestone, and as silicate in mica, asbestos, soapstone, meerschaum, talc, and in other minerals. It also accompanies Ca in the forms in which it is found in the animal and vege- table worlds. It is prepared by heating its chloride with Na. It is a hard, light, mal- leable, ductile, white metal. It burns with great brilliancy when heated in air (magnesium light), but may be distilled in H. It decomposes vapor of H.,0 when heated; reduces CO., with the aid of heat, and combines directly with Cl, S, P, As, and N. It dissolves in dilute acids, but is not affected by alkaline solutions. Compounds of Magnesium. Magnesium Oxide—Calcined magnesia—magnesia (C. S.; Br.)— MgO—40—is obtained by calcining tlie carbonate, hydrate, or nitrate. It is a light, bulky, tasteless, odorless, amorphous, white powder; alkaline in reaction ; almost insoluble in H O; readily soluble without effervescence in acids. Magnesium Hydrate — MgH.,02 — 58 — occurs in nature, and is formed when a solution of a Mg salt is precipitated with excess of NaHO in absence of ammoniacal salts. It is a heavy, white powder, insoluble inH20; absorbs C02. Magnesium Chloride—MgCl2—95—is formed when MgO or MgC03 is dissolved in HC1. It is an exceedingly deliquescent, soluble substance, which is decomposed into HC1 and MgO when its aqueous solutions are evaporated to dryness, Salts of Magnesium. Magnesium Sulphate—Epsom salt—Sedlitz salt—Magnesii sulphas (U. S.)—Magnesice sulphas (Br.)—MgSO( + 7 Aq—120 + 126—exists in solution in sea-water and in the waters of many mineral springs, especially those known as bitter waters. It is formed by the action of H2S04 on Mg COa. It crystallizes in right rhombic prisms ; bitter; slightly efferves- cent, and quite soluble in H.,0. Heated, it fuses and gradually loses 6 Aq up to 132° (269°.6 F.); the last Aq it loses at 210° (410° F.). Phosphates.—Resemble those of Ca in their constitution and proper- ties, and accompany them in the situations in which they occur in the ani- mal body, but in much smaller quantity. Magnesium also forms double phosphates, constituted by the substitu- tion of one atom of the bivalent metal for two of the atoms of basic hy- drogen, of a molecule of phosphoric acid and of an atom of an alkaline metal, or of an ammonium group, for the remaining basic hydrogen. Ammonio-Magnesian Phosphate—Triple phosphate—Mg(NH)P04 4- 6 Aq —137 + 108—is produced when an alkaline phosphate and XH.HO are 154 MANUAL OF CHEMISTRY. added to a solution containing Mg. When heated it is converted into mag- nesium pyrophosphate MgoP.,0., in which form H3P04 and Mg are usually weighed in quantitative analysis. In the urine, alkaline phosphates and magnesium salts are always present, and consequently when, by decomposition of urea, the urine be- comes alkaline, the conditions for the formation of this compound are fulfilled; and being practically insoluble, especially in the presence of excess of phosphates and of ammonia, it is deposited in crystals, usually tabular, sometimes feathery and stellate in form. When it is formed in the bladder, in the presence of some body to serve as a nucleus, the crystallization takes place upon the nucleus and a fusible calculus is produced. Carbonates.—Magnesium Carbonate—Neutral carbonate—MgC03—84 —exists native in magnesite, and, combined with CaC03, in dolomite. It cannot be formed, like other carbonates, by decomposing a Mg salt with an alkaline carbonate, but may be obtained by passing C02 through H..O holding tetramagnesic tricarbonate in suspension. Trimagnesic Dicarbonate— (MgC03)2MgH202 + 2 Aq—226 + 36—is formed in small crystals when a solution of MgS04 is precipitated with ex- cess of Na2C03 and the mixture boiled. Tetramagnesic Tricarbonate—Magnesia alba—Magnesii carbonas (U. S.)— Magnesite carbonas {Br.)—3(MgCO.J]YrgH2C>2 + 3 Aq—310 + 54—occurs in commerce in light, white cubes, composed of a powder which is amorphous or partly crystalline. It is prepared by precipitating a solution of MgS04 with one of Na2C03; if the precipitation occur in cold dilute solutions {Magnesice carbonas Icevis, Br.), very little C02 is given off; a light, bulky precipitate falls, and the solution contains magnesium, probably in the form of the bicarbonate Mg(HC03)2 ; this solution, on standing, deposits crystals of the carbonate, MgC03 + 3 Aq. If hot concentrated solutions be used and the liquid then boiled upon the precipitate, C02 is given off, and a denser, heavier precipitate is formed, which varies in composition according to the length of time during which the boiling is continued, and to the presence or absence of excess of sodium carbonate. The pharmaceutical product frequently contains 4(MgC03),MgH202 + 4H20, or even 2(MgC03),MgHo02 + 2H O. All of these compounds are very sparingly soluble in H20, but much more soluble in H20 containing am- moniacal salts. Analytical Characters. (1.) Ammonium hydrate : voluminous, white ppt. from neutral solu- tions. (2.) Potash or soda: voluminous, white ppt. from warm solutions; prevented by the presence of NH, salts and of certain organic substances. (3.) Ammonium carbonate : slight ppt. from hot solutions ; prevented by the presence of NH4 salts. (4.) Sodium or potassium carbonate : white ppt., best from hot solu- tion ; prevented by the presence of NH, compounds. (5.) Disodic phosphate : white ppt. in hot, not too dilute solutions. (6.) Oxalic acid : nothing alone, but in presence of NH,HO a white ppt.; not formed in presence of NH4C1 or salts of NH,. COMPOUNDS OF ZINC. 155 ZINC. Symbol = Zn—Atomic weight = 64.9—Molecular weight = 64.9—Sp. gr. = 6.862—7.215—Fuses at 415° (779° F.)—Distils at 1040° (1904° F.). Occurs principally in calamine (ZnC03) ; and blende (ZnS); also as oxide and silicate; never free. It is separated from its ores by calcining, roasting, and distillation. It is a bluish-white metal; crystalline, granular, or fibrous ; quite mal- leable and ductile when pure. The commercial metal is usually brittle. At 130°-150° (266°-302° F.) it is pliable, and becomes brittle again above 200°-210° (392°-410° F.). At 500° (9323 F.) it burns in air with a greenish-white flame, and gives off snowy white flakes of the oxide (lana philosophica ; nil album ; pompho- lix). In moist air it becomes coated with a film of hydrocarbonate. It de- composes steam when heated. Pure H.,S04 and pure Zn do not react together in the cold ; if the acid be diluted, however, it dissolves the Zn with evolution of H and formation of ZnS04, in the presence of a trace of Pt or Cu. The commercial metal dissolves readily in dilute H2S04, with evolution of H and formation of ZnS04, the action being accelerated in presence of Pt, Cu, or As. Zinc surfaces thoroughly coated with a layer of an amalgam of Hg and Zn are only attacked by H„S04 if they form part of closed galvanic circuit; hence the zincs of galvanic batteries are protected by amalgamation. Zinc also decomposes HNG3, HC1, and acetic acid. When required for toxicological analysis, zinc must be perfectly free from As and sometimes from P. It is better to test samples until a pure one is found than to attempt the purification of a contaminated metal. Zinc surfaces are readily attacked by weak organic acids ; vessels of galvanized iron or sheet zinc should therefor never be used to contain arti- cles of food or medicines. Compounds of Zinc. Zinc Oxide—Zinci oxidum (U. S.; Br.)—ZnO—80.9—is prepared either by calcining the precipitated carbonate, or by burning Zn in a cur- rent of air. An impure oxide, known as tutty, is deposited in the Hues of zinc furnaces and in those in which brass is fused. When obtained by cal- cination of the carbonate, it forms a soft, white, tasteless, and odorless powder; when produced by burning the metal, it occurs in light, volumi- nous, white masses. It is neither fusible, volatile, nor decomposable by heat, and is completely insoluble in neutral solvents. It dissolves in dilute acids, with formation of the corresponding salts. It is used in the arts as a white pigment in place of lead carbonate, and is not darkened by H2S. Zinc Hydrate—ZoH202—98.9—is not formed by union of ZnO and HO ; but is produced when a solution of a Zn salt is treated with KHO. Freshly prepared, it is very soluble in alkalies and in solutions of NH4 salts. Zinc Chloride—Butter of zinc—Zinci chloridum (U. S. ; Br.)—ZnCl2 + Aq—135.9 18—is obtained by dissolving Zn in HC1; or by heat- ing Zn in Cl. It is a soft, white, very deliquescent, fusible, volatile mass ; 156 MANUAL OF CHEMISTRY. very soluble in H20, somewhat less so in alcohol. Its solution has a burning metallic taste ; destroys vegetable tissues ; dissolves silk ; and ex- erts a strong dehydrating action upon organic substances in general. In dilute solution it is used as a disinfectant and antiseptic (Burnett’s fluid), as a preservative of wood and as an embalming injection. Salts of Zinc. Zinc Sulphate—White vitriol—Zinci sulphas (U. S. ; Br.)—ZnSO -f ??Aq—160.9+ wl8—is formed when Zn, ZnO, ZnS, or ZnC03 is dissolved in diluted H,S04. It crystallizes below 30c (86° F.) with 7 Aq; at 30° (86° F.) with 6 Aq; between 40°-50° (104°-122 F ) with 5 Aq ; at 0° (32° F.) from concentrated acid solution with 4 Aq ; from a boiling solu- tion it is precipitated by concentrated H2S04 with 2 Aq ; from a saturated solution at 100° (212° F.) with 1 Aq; and anhydrous when the salt with 1 Aq is heated to 238° (460° F.). The salt usually met with is that with 7 Aq, which is in large, colorless, four-sided prisms ; efflorescent; very soluble in H.,0 ; sparingly soluble in weak alcohol. Its solutions have a strong, styptic taste ; coagulate albumin when added in moderate quantity, the coagulum dissolving in an excess ; and form insoluble precipitates with the tannins. Carbonates.—Zinc Carbonate—ZnCO.,—124.9—occurs in nature as calamine. If an alkaline carbonate be added to a solution of a Zn salt, the neutral carbonate, as in the case of Mg, is not formed, but an oxycarbo- nate, wZnC03, nZnH.,0., [Zinci carbonas (C. S.; Br.)\, whose composition varies with the conditions under which it is formed. Analytical Characters. (1.) Hydrate of Iv, Na or NH4 : white ppt., soluble in excess. (2.) Carbonate of K or Na: white ppt., in absence of NH4 salts. (3.) Hydrogen sulphide, in neutral solution : white ppt. In presence of an excess of a mineral acid, the formation of this ppt. is prevented un- less sodium acetate be also present. (4.) Ammonium sulphydrate : white ppt., insoluble in excess, in IvHO, NH4HO, or acetic acid ; soluble in dilute mineral acids. (5.) Ammonium carbonate: white ppt., soluble in excess. (6.) Disodic phosphate, in absence of NH4 salts : white ppt., soluble in acids or alkalies. (7.) Potassium ferrocyanide : white ppt., insoluble in HC1. Action on the Economy. All the compounds of Zn which are soluble in the digestive fluids be- have as true poisons ; and solutions of the chloride (in common use by tinsmiths, and in disinfecting fluids) have also well-marked corrosive properties. When Zn compounds are taken, it is almost invariably by mistake for other substances : the sulphate for Epsom salt, and solutions of the chloride for various liquids, gin, fluid magnesia, vinegar, etc. Metallic zinc is dissolved by solutions containing NaCl, or organic acids, for which reason articles of food kept in vessels of galvanized iron COBALT. 157 become contaminated with zinc compounds, and, if eaten, produce more or less intense symptoms of intoxication. For the same reason materials intended for analysis, in cases of supposed poisoning, should never be packed in jars closed by zinc caps. CADMIUM. Symbol = Cd—Atomic weight — 111.8—Molecular weight = 111.8—Sp. gr. =8.604—Fuses at 227°.8 (442° F.)—Boils at 860° (1580° F.). A white metal, malleable and ductile at low temperature, brittle when heated; which accompanies Zn in certain of its ores. It resembles zinc in its physical as well as its chemical characters. It is used in certain fusible alloys, and its iodide is used in photography. Analytical Characters.—Hydrogen sulphide: bright yellow ppt.; insol- uble in NH4HS and in dilute acids and alkalies, soluble in boiling HXO, or HC1. V. NICKEL GROUP. NICKEL C OBALT. These two elements bear some resemblance chemically to those of the Fe group ; from which they differ in forming, so far as known, no com- pounds similar to the ferrates, chromates, and manganates. They form compounds cori’esponding to Fe,03, but those corresponding to the ferric series are either wanting or exceedingly unstable. NICKEL. Symbol = Ni—Atomic weight = 58—Sp. gr. — 8.637. Occurs in combination with S, and with S and As. It is a white metal, hard, slightly magnetic, not tarnished in air. German silver is an alloy of Ni, Cu, and Zn. Its salts are green. Analytical Characters. (1.) Ammonium sulpliydrate : black ppt. ; insoluble in excess. (2.) Potash or soda : apple-green ppt., in absence of tartaric acid ; insoluble in excess. (3.) Ammonium hydrate : apple-green ppt. ; soluble in excess, form- ing a violet solution which deposits the apple-green hydrate when heated with KHO. COBALT Symbol = Co—Atomic weight = 58.9—Sp. gr. = 8.5-8.7. Occurs in combination with As and S. Its salts are red when hydrated, and usually blue when anhydrous. Its phosphate is used as a blue pig- ment. 158 MANUAL OF CHEMISTRY. Analytical Characters. (1.) Ammonium sulphydrate: black ppt. ; insoluble in excess. (2.) Potash: blue ppt.; turns red, slowly in the cold, quickly when heated ; not formed in the cold in presence of NH4 salts. (3.) Ammonium hydrate: blue ppt. ; turns red in absence of air, green in its presence. VI. COPPER GROUP. Copper—Mercury. Each of these elements forms two series of compounds : one contains / Cu\Y' compounds of the bivalent group (I )) or (Ilg,)" which are designated \ Cu'/ by the termination ous; the other contains compounds of single, bivalent atoms Cu" or Hg", which are designated by the termination ic. COPPER Symbol = Cu (CUPRUM) —Atomic weight = 63.1—Molecular weight = 127 (?)—Sp. gr. = 8.914-8.952—Euses at 1091° (1996° F.). Occurrence.—It is found free in crystals or amorphous masses, some- times of great size ; also a sulphide, copper pyrites; oxide, ruby ore and black oxide ; and basic carbonate, malachite. Properties.—Physical.—A yellowish-red metal; dark brown when finely divided ; very malleable, ductile, and tenacious ; a good conductor of heat and electricity; has a peculiar, metallic taste and a characteristic odor. Chemical.—It is unaltered in dry air at the ordinary temperature ; but when heated to redness is oxidized to CuO. In damp air it becomes coated with a brownish film of oxide ; a green film of basic carbonate ; or, in salt air, a green film of basic chloride. Hot H.,S04 dissolves it with formation of CuS04 and SO„ ; it is dissolved by HN03 with formation of Cu(N03)2 and NO ; and by HC1 with liberation of H Weak acids form with it soluble salts in presence of air and moisture. It is dissolved by NHHO, in presence of air, with formation of a blue solution. It combines directly with Cl, frequently with light. Compounds of Copper. Oxides.—Cuprous Oxide—Suboxide or red oxide of copper—(Cu iO— 142.4—is formed by calcining a mixture of (Cu.,)Cl2 and Na„C03 ; or a mixture of CuO and Cu. It is a red or yellow powder ; permanent in air ; sp. gr. 5.749-G.093 ; fuses at a red beat; easily reduced by C or H. Heated in air it is converted into CuO. Cupric Oxide—Binoxide or black oxide of coppei—CuO—79.2—is pre- pared by heating Cu to dull redness in air ; or by calcining Cu(N03)2 ; or by prolonged boiling of the liquid over a precipitate produced by heating SALTS OF COPPEIi. 159 a solution of a cupric salt, in presence of glucose, with KHO. By the last method it is sometimes produced in Trommer’s test for sugar, when an excessive quantity of CuS04 has been used. It is a black, or dark reddish-brown, amorphous solid ; readily reduced by C, H, Na, or K at comparatively low temperatures. When heated with organic substances it gives up its O, converting the C into CO., and the H into H.,0 : CaHrtO + 6CuO = 6Cu + 2CO, + 3H„0 ; a property which renders it valuable in organic analysis, as by heating a known weight of organic substance with CuO and weighing the amount of C02 and H20 produced, the percentage of C and H may be obtained. It dissolves in acids with formation of salts. Hydrates.—Cuprous Hydrate—(Cu).,H Q, (?)—160.4 (?)—is formed as a yellow or red powder when mixed solutions of CuS04 and KHO are heated in presence of glucose. By boiling the solution it is rapidly dehy- drated with formation of (Cu2)0. Cupric Hydrate—CuH,02—97.2—is formed by the action of KHO upon solution of CuS04, in absence of reducing agents and in the cold. It is a bluish, amorphous powder; very unstable, and readily dehydrated, with formation of CuO. Sulphides.—Cuprous Sulphide—Subsulphide or jyrotosulphide of copper —Cu2S—158.4—occurs in nature as copper glance or chalcosine, and in many double sulphides, pyrites. Cupric Sulphide—CuS—95.2—is formed by the action of H,S or of NH4HS on solutions of cupric salts. It is almost black when moist, greenish-brown when dry. Hot HN03 oxidizes it to CuS04 ; hot HC1 converts it into CuCl.,, with separation of S, and formation of H.,S. It is sparingly soluble in NH HS, its solubility being increased by the pres- ence of organic matter. Chlorides.—Cuprous Chloride—Subchloride or protochloride—(Cu2)Cl2 —197.4—i3 prepared by heating Cu with one of the chlorides or Hg; by dissolving (Cu2)0 in HC1, without contact of air ; or by tho action of reducing agents on solutions of CuCl2. It is a heavy, white powder; turns violet and blue by exposure to light; soluble in HC1; insoluble in H„Q. It forms a crystallizable compound with CO; and its solution in HOI is used in analysis to absorb that gas. Cupric Chloride—Chloride or deutochloride—CuCl2—134.2—is formed by dissolving Cu in aqua regia ; if the Cu be in excess, it reduces CuCl2 to (Cu.,)Cl2. It crystallizes in bluish-green, rhombic prisms with 2 Aq °} deli- quescent ; very soluble in H20 and in alcohol. Salts of Copper. Cupric Nitrate—Cu(N03)2—187.2—is formed by dissolving Cu, CuO, or CuCO., in HNO... It crystallizes at 20°-25° (68°-77° F.) with 3 Aq ; below 20° (68° F.) with 6 Aq, forming blue, deliquescent needles. Strongly heated, it is converted into CuO. Cupric Sulphate—Blue vitriol—Blue stone—Cupri sulphas (U. S.; Br.) —CuSO, + 5 Aq—159.2 -f 90—is prepared: (1) by roasting CuS ; (2) from the water of copper mines ; (3) by exposing Cu, moistened with di- lute H„SO , to air ; (4) by heating Cu with H2S04. As ordinarily crystallized, it is in tine, blue, oblique prisms ; soluble in H.,0; insoluble in alcohol; efflorescent in dry air at 15° (59° F.), losing 2 Aq. At 100° (212° F.) it still retains 1 Aq, which it loses at 230° (446° MANUAL OF CHEMISTRY. F.), leaving a white, amorphous powder of the anhydrous salt, which, on taking up H.20, resumes its blue color. Its solutions are blue, acid, styptic, and metallic in taste. When NH,HO is added to a solution of CuS04, a bluish-white precip- itate falls, which redissolves in excess of the alkali, to form a deep blue solution ; strong alcohol floated over the surface of this solution separates long, right rhombic prisms, having the composition CuS04,4NH3 + H.,0, which are very soluble in H20. This solution constitutes ammonio- sulphate of copper or aqua sapphirina. Arsenite—Scheele's green—Mineral green—is a mixture of cupric arsenite and hydrate ; prepared by adding potassium arsenite to solution of CuS04. It is a grass-green powder, insoluble in H20 ; soluble in NH HO, or in acids. Exceedingly poisonous. Schweinfurt Green—Mitis green or Paris green—is the most frequently used, and the most dangerous of the cupro-arscnical pigments. It is pre- pared by adding a thin paste of neutral cupric acetate with H20 to a boil- ing solution of arsenious acid, and continuing the boiling during a further addition of acetic acid. It is an insoluble, green, crystalline powder, having the composition (C,,II30.,)2Cu + 3(As.,04Cu). It is decom- posed by prolonged boiling in H20, by aqueous solutions of the alkalies, and by the mineral acids. Carbonates.—The existence of cuprous carbonate is doubtful. Cu- pric carbonate—CuC03—exists in nature, but has not been obtained ar- tificially. Dicupric carbonate—CuC0s,CuH.,02—exists in nature as mala- chite. When a solution of a cupric salt is decomposed by an alkaline car- bonate, a bluish precipitate, having the composition CuC03,CuH.,02 4- H O, is formed, which, on drying, loses H20, and becomes green ; it is used as a pigment under the name mineral green. Tricupric carbonate— Sesquicarbonate of copper—2(CuC03),CuH.,02—exists in nature as a blue mineral called azurite or mountain blue, and is prepared by a secret pro- cess for use as a pigment known as blue ash. Acetates.—Cupric Acetate—Diacetate—Crystals of Venus—Cupriace- tas (U. S.)—Cu(C2H302)2 + Aq —181.2 + 18—is formed when CuO or ver- digris is dissolved in acetic acid ; or by decomposition of a solution of CuS04 by Pb(C2H30„).. It crystallizes in large, bluish-green prisms, which lose their Aq at 140° (284° F.). At 240°-260° (464°-500° F.) they are decomposed wfitli liberation of glacial acetic acid. Basic Acetates— Verdigris—is a substance prepared by exposing to air piles composed of alternate layers of grape-skins and plates of copper, and removing the bluisli-green coating from the copper. It is a mixture, in varying proportions, of three different substances : (C„H 0,)..CuH203 -+- SAq; [(aifl,01),Cu]„CuHA + 5Aq; and (CtH>0,),Cu,2(CuH,0!). Analytical Characters. Cuprous—are very unstable and readily converted into cupric com- pounds. (1.) Potash: white ppt. ; turning brownish. (2.) Ammonium hydrate, in absence of air : a colorless liquid ; turns blue in air. oupric—are white when anhydrous ; when soluble in H,0 they form blue or groon, acid solutions. (1.) Hydrogen sulphide : black ppt. ; insoluble in KHS or Nall S; spar- ACTIOX OX THE ECOXOIIY. 161 ingly soluble in NH^HS; soluble in hot concentrated HNO and in KCN. (2.) Alkaline sulphydrates : same as H.,S. (3.) Potash or soda: pale blue ppt. ; insoluble in excess. If the solu- tion be heated over the ppt., the latter contracts and turns black. (4.) Ammonium hydrate, in small quantity : pale blue ppt. ; in larger quantity, deep blue solution. (5.) Potassium or sodium carbonate : greenish-blue ppt.; insoluble in excess ; turning black when the liquid is boiled. (6.) Ammonium carbonate : pale blue ppt. ; soluble with deep blue color in excess. (7.) Potassium cyanide : greenish-yellow ppt.; soluble in excess. (8.) Potassium ferrocyanide : chestnut-brown ppt.; insoluble in weak acids; decolorized by KUO. (9.) Iron is coated with metallic Cu. Action on the Economy. The opinion, until recently universal among toxicologists, that all the compounds of copper are poisonous, has been much modified by recent researches. Certain of the copper compounds, such as the sulphate, hav- ing a tendency to combine with albuminoid and other animal substances, produce symptoms of irritation by their direct local action, when brought in contact writh the gastric or intestinal mucous membrane. One of the characteristic symptoms of such irritation is the vomiting of a greenish matter, which develops a blue color upon the addition of NH4HO. Cases are not wanting in which severe illness, and even death, has followed the use of food which has been in contact with imperfectly tinned copper vessels; cases in which nervous and other symptoms re- ferable to a truly poisonous action have occurred. As, however, it has also been shown that non-irritant, pure copper compounds may be taken in considerable doses with impunity, it appears at least probable that the poisonous action attributed to copper is due to other substances. The tin and solder used in the manufacture of copper utensils contain lead, and in some cases of so-called copper-poisoning, the symptoms have been such as are as consistent with lead-poisoning as with copper-poisoning. Copper is also notoriously liable to contamination with arsenic, and it is by no means improbable that compounds of that element are the active poisonous agents in some cases of supposed copper-intoxication. Nor is it improbable that articles of food allowed to remain exposed to air in copper vessels should undergo those peculiar changes which result in the formation of poisonous substances, such as the sausage- or cheese-poisons, or the ptomaines. The treatment, when irritant copper compounds have been taken, should consist in the administration of white of egg or of milk, with whose albuminoids an inert compound is formed by the copper salt. If vomiting do not occur spontaneously, it should be induced by the usual methods. The detection of copper in the viscera after death is not without interest, especially if arsenic have been found, in wdiich case its discovery or non-discovery enables us to differentiate between poisoning by the ar- senical greens and that by other arsenical compounds. The detection of mere traces of copper is of no significance, because, although copper is 162 MANUAL OF CHEMISTRY. not a physiological constituent of the body, it is almost invariably pres- ent, having been taken with the food. Pickles and canned vegetables are sometimes intentionally greened by the addition of copper ; this fraud is readily detected by inserting a large needle into the pickle or other vegetable ; if copper be present the steel will be found to be coated with copper after half an hour’s contact. MERCURY. Symbol = Hg (HYDRARGYRUM)— Atomic weight = 199.7 — Mo- lecular weight = 199.7—Sp. gr. of liquid = 13.596 ; of vapor = 6.97—Fuses at —38°.8 (—37°.9 F.)—Boils at 350° (662° F.). Occurrence.—Chiefly as cinnabar (HgS) ; also in small quantity free and as chloride. Preparation.—The commercial product is usualty obtained by simple distillation in a current of air : HgS + 02 = Hg + S02. If required pure, it must be freed from other metals by distillation, and agitation of the re- distilled product with mercurous nitrate solution, solution of Fe2Clc, or dilute HN03. Properties.—Physical.—A bright metallic liquid ; volatile at all tempera- tures. Crystallizes in octahedra of sp. gr. 14.0. When pure it rolls over a smooth surface in round drops ; the formation of tear-sliaped drops in- dicates the presence of impurities. Chemical.—If pure it is not altered by air at the ordinary temperature, but if contaminated with foreign metals its surface becomes dimmed. Heated in air it is oxidized superficially to HgO. It does not decompose H,0. It combines directly with Cl, Br, I and S. It alloys readily with most metals to form amalgams. It amalgamates with Fe and Pt only with difficulty. Hot concentrated HSO, dissolves it with evolution of SO, and formation of HgS04. It dissolves in cold HNOa with formation of a nitrate. Elementary mercury is insoluble in H O, and probably in the digestive liquids. It enters, however, into the formation of three medicinal agents : hydrargyrum cum creta (27. S. ; Br.); massa hydrargyri (27. S.) = pilula hydrargyri (Br.); and unguentum hydrargyri (27. S.; Br.), all of which owe their efficacy, not to the metal itself, but to a certain proportion of oxide produced during their manufacture. The fact that blue mass is more active than mercury with chalk is due to the greater proportion of oxide contained in the former. It is also probable that absorption of vapor of Hg by cutaneous surfaces is attended by its conversion into HgCl,. Compounds of Mercury. Oxides.—Mercurous Oxide—Protoxide or black oxide of mercury— (HgjO- -415.4—is obtained by adding a solution of (Hg„)(NO,), to an excess of solution of KHO. It is a brownish-black, tasteless powder; very prone to decomposition into HgO and Hg. It is converted into (Hg2)Cl2 by HC1; and by other acids into the corresponding mercurous salts. It is formed by the action of CaH202 on mercurous compounds, and ex- ists in black wash. COMPOUNDS OF MERCURY. 163 Mercuric Oxide—Red, or binoxide of mercury—Hydrargyri oxidum fa- vum (U. S.: Br.)—Hydrargyri oxidum rubrum (U. S. ; Br.)—HgO—2i5.7 —is prepared by two methods(1) by calcining Hg(N03)2 as long as brown fumes are given off (Hydr. oxid. rubr.); or, (2) by precipitating a solution of a mercuric salt by excess of KHO (Hydr. oxid.Jiavum). The products obtained, although the same in composition, differ in physical characters and in the activity of their chemical actions. That obtained by (1) is red and crystalline ; that obtained by (2) is yellow and amorphous. The latter is much the more active in its chemical and medicinal actions. It is very sparingly soluble in H.,0, the solution having an alkaline re- action and a metallic taste. It exists both in solution and in suspension in yellow icash, prepared by the action of CaH.,0, on a mercuric compound. Exposed to light and air it turns black, more rapidly in presence of organic matter, giving off O and liberating Hg: HgO = Hg + O. It decomposes the chlorides of many metallic elements in solution, with for- mation of a metallic oxide and mercuric oxychlorides. It combines with alkaline chlorides to form soluble double chlorides, called chloromercurates or chlorhydrargyrates; and forms similar compounds with alkaline iodides and bromides. Sulphides.—Mercurous Sulphide—(Hg„)S—431.4 — a very unstable compound, formed by the action of H.,S on mercurous salts. Mercuric Sulphide—Red sulphide of mercury—Cinnabar—Vermilion— Hydrargyri sulphidum rubrum (U. S.)—HgS—231.7—exists in nature in amorphous red masses, or in red crystals, and is the chief ore of Hg. If Hg and S be ground up together in the cold, or if a solution of a mercuric salt be completely decomposed by H..S, a black sulphide is obtained, which is the JEthiops mineralis of the older pharmacists. A red sulphide is obtained for use as a pigment (vermilion), by agitat- ing for some hours at 60° (140° F.) a mixture of Hg, S, KHO, and H.,0. It is a fine, red powder, which turns brown, and finally black, when heated. Heated in air, it burns to S02 and Hg. It is decomposed by strong H2S04, but not by HN03 or HC1. Chlorides.—Mercurous Chloride—Frotochloride or mild chloride of mer- cury—Calomel—Hydrargyri chloridum mite (U. S.)—Hydrargyri subchlori- dum (Br.) — (Hg„)Cl,—470.4—is now principally obtained by mutual decomposition of NaCl and (Hg2)S04. Mercuric sulphate is first obtained by heating together 2 pts. Hg and 3 pts. H2S04; the product is then caused to combine with a quantity of Hg equal to that first used, to form (Hg 2)S04 ; which is then mixed with dry NaCl, and the mixture heated in glass vessels, connected with condensing chambers ; 2NaCl + (Hg2)S04 = NaaS04 + (Hg2)Cl2. In practice, varying quantities of HgCl., are also formed, and must be removed from the product by washing with boiled, distilled H.,0 until the washings no longer precipitate with NH4HO. The presence of HgCl2 in calomel may be detected by the formation of a black stain upon a bright iron surface, immersed in the calomel, moistened with alcohol ; or by the production of a black color by H2S in II.,0 which has been in contact with and filtered from calomel so contaminated. Calomel is also formed in a number of other reactions : (1) by the ac- tion of Cl upon excess of Hg ; (2) by the action of Hg upon Fe2Cl6; (3) by the action of HC1, or of a chloride, upon (Hg2)0, or upon a mercurous salt; (4) by the action of reducing agents, including Hg, upon HgCl.,. Calomel crystallizes in nature, and when sublimed, in quadratic prisms. When precipitated it is deposited as a heavy, amorphous, white powder, MANUAL OF CHEMISTRY. faintly yellowish, and producing a yellowish mark when rubbed upon a dark surface. It sublimes, without fusing, between 420° and 500° (788°- 932° F.), is insoluble in cold H„0 and in alcohol; soluble in boiling H.,0 to the extent of 1 part in 12,000 ; when boiled with H„0 for some time, it suffers partial decomposition, Ilg is deposited and HgCl2 dissolves. Although Hg2Cl2 is insoluble in H20, in dilute HC1, and in pepsin solution, it is dissolved at the body temperature in an aqueous solution of pepsin acidulated with HC1. When exposed to light, calomel becomes yellow, then gray, owing to partial decomposition, with liberation of Hg and formation of HgCl„ : (Hg„)Cl2 — Hg + HgCl2. It is converted into HgCl, by Cl or aqua regia : (Hg2)Cl2 + Cl3 = 2HgCl2. In the presence of H..O, I converts it into a mixture of HgCl„ and Hgl2: (Hg2)Cl, 4- I2 = HgCl, + Hgl„. It is also converted into HgCl, by HC1 and by alkaline chlorides : (Hg2)Cl2 = HgCl2 + Hg. This change occurs in the stomach when calomel is taken inter- nally, and that to such an extent when large quantities of NaCl is taken with the food, that calomel cannot be used in naval practice as it may be with patients who do not subsist upon salt provisions. It is converted by KI into (Hg„)I.,: (HgjCP + 2IvI — 2KC1 ,-t- (Hg4)I2 ; which is then decomposed by excess of Ivl into Hg and IIgI2, the latter dissolving : (Hg)2I2 = Hg Hgl.,. Solutions of the sulphates of Na, K, and NH, dissolve notable quantities of (HgjCl,. The hydrates and carbonates of K and Na decom- pose it with formation of (Hg2)0: (Hg2)Cl2 + Na2COs = (Hg2)0 -f C02 + 2NaCl; and the (Hg2)0 so formed is decomposed into HgO and Hg. If alkaline chlorides be also present, they react upon the HgO so pro- duced, with formation of HgCl.,. Mercuric Chloride—Perchloride or bichloride of mercury—Corrosive sublimate—Hydrargyri chloridum corrosivum (U. S.)—Hydrargyri perchlori- dum {Br.)—HgCl2—270.7—is prepared by heating a mixture of 5 pts. dry HgS04 with 5 pts. dry NaCl, and 1 pt. MnO., in a glass vessel communi- cating with a condensing chamber. It crystallizes by sublimation in octahedra, and by evaporation of its solutions in flattened, right rhombic prisms; fuses at 265° (509' F.), and boils at about 295° (563° F.) ; soluble in H20 and in alcohol ; very soluble in hot HC1, the solution gelatinizing on cooling. Its solutions have a dis- agreeable, acid, styptic taste, and are highly poisonous. It is easily reduced to (Hg2)Cl,2 and Hg, and its aqueous solutions are so decomposed when exposed to light; a change which is retarded by the presence of NaCl. Heated with Hg it is converted into (Hg0)Cl„. When dry HgCl, or its solution is heated with Zn, Cd, Ni, Fe, Pb, Cu, or Bi, those elements remove part of all of its Cl, with separation of (Hg2)Cl2 or Hg. Its solution is decomposed by H.,S with separation of a yellow sulpho- chloride, which, with an excess of the gas, is converted into black HgS. It is soluble without decomposition in HS04,HN03, and HC1. It is decom- posed by IvHO or NaHO, with separation of a brown oxychloride if the alkaline hydrate be in limited quantity ; or of the orange-colored HgO if it be in excess. A similar decomposition is effected by CaH202 and Mg H.,0„ ; which does not, however, take place in presence of an alkaline chloride, or of certain organic matters, such as sugar and gum. Many organic substances decompose it into (Hg2)Cl2 and Hg, especially under the influence of sunlight. Albumen forms with it a white precipitate, which is insoluble in H20, but soluble in an excess of fluid albumen and in solutions of alkaline chlorides. It readily combines with metallic chlorides, to form soluble double chlorides, called chloromercurales or chlor- 165 SALTS OF MERCURY. hydrargyrates. One of these, obtained in flattened, rhombic prisms, by the cooling of a boiling solution of HgCl., and XH4C1, has the composition HgCla, 2(NH4C1) + Aq, and was formerly known as sal alembroth or sal sapientice. Mercurammonium Chloride — Mercury chloramidide — Infusible white precipitate—Ammoniated mercury—Hydrargyrum ammoniatum (U. S. ; Br.) —NHHgCl —251.1—is prepared by adding a slight excess of XH4HO to a solution of HgCl.,. It is a white powder, insoluble in alcohol, ether, and cold H,0 ; decomposed by hot H,0 with separation of a heavy, yellow powder. It is entirely volatile without fusion. The fusible white precipi- tate is formed in small crystals when a solution containing equal parts of HgCl, and NH4C1 is decomposed by Na,C03. It is mereurdiammonium chloride, NH4HgCl,NH4Cl. Iodides.—Mercurous Iodide—Protoiodide or yellow iodide—Hydrargyri iodidum viride (U. S. ; Br.)—Hg.,I,,—653.4—is prepared by grinding to- gether 200 pts. Hg and 127 pts. I with a little alcohol until a green paste is formed. It is a greenish-yellow, amorphous powder, insoluble in HO and in alcohol. When heated it turns brown and volatilizes com- pletely. When exposed to light, or even after a time in the dark, it is de- composed into Hgl, and Hg. The same decomposition is brought about instantly by KI; more slowly by solutions of alkaline chlorides and by HC1 when heated. NH4HO dissolves it with separation of a gray pre- cipitate. Mercuric Iodide—Biniodide or red iodide—Hydrargyri iodidum rubrum (U. S.; Br.)—Hgla—453.7—is obtained by double decomposition between HgCl„ and KI, care being had to avoid too great an excess of the alkaline iodide, that the soluble potassium iodhydrargvrate may not be formed. It is sparingly soluble in H,0 ; but forms colorless solutions with alcohol. It dissolves readily in many dilute acids and in solutions of am- moniacal salts, alkaline chlorides, and mercuric salts ; and in solutions of alkaline iodides. Iron and copper convert it into (Hg.,)I„, then' into Hg. The hydrates of K and Na decompose it into oxide or oxyiodide, and com- bine with another portion to form iodhydrargyrates, which dissolve. XH HO separates from its solution a brown powder, and forms a yellow solution which deposits white flocks. Cyanides.—Mercuric Cyanide—Hydrargyricyanidum (V. -S'.)—Hg(CN)3 —251.7—is best prepared by heating together, for a quarter of an hour, potassium ferrocyanide, 1 pt. ; HgS04, 2 pts.; and H O, 8 pts. It crystal- lizes in quadrangular prisms ; soluble in 8 pts. of cold H.,0, much less soluble in alcohol; highly poisonous. When heated dry it blackens, and is decomposed into (CN)2 and Hg ; if heated in presence of H,0 it yields HCN, Hg, C03, and NH3. Hot" concentrated and HC1, HBr, HI, and H,S in the cold, decompose it with liberation of HCN. It is not de- composed by alkalies. Salts of Mercury. Nitrates.—There exist, besides the normal nitrates : (Hg„)(NO,(),, and Hg(NO„)„, three basic mercurous nitrates, three basic mercuric nitrates, and a mercuroso-mercuric nitrate. Mercubous Nitrate—(Hga)(NO?)s -u 2 Aq—523.4 + 36 — is formed when excess of Hg is digested with HN03, diluted with \ vol. H.,0 ; until short, prismatic crystals separate. MANUAL OF CHEMISTRY. It effloresces in air ; fuses at 70° (158° F.) ; dissolves in a small quantity of hot HO, but with a larger quantity is decomposed with separation of the yellow, basic trimercuric nitrate, Hg(N03)2, 2HgO -f- Aq. Dimercurous Nitrate.—(Hg2)(N03)2,Hg.20 -f Aq—938.8 4- 18—is formed by acting upon the preceding salt with cold H O until it turns lemon-yellow ; or by extracting with cold H20 the residue of evaporation of the product obtained by acting upon excess of Hg with concentrated HNOa. Trimercurous Nitrate—(Hg2)?(NOa)4, Hg.O + 3 Aq—14G2.2 + 54— is obtained in large, rhombic prisms, when excess of Hg is boiled with HNO,, diluted with 5 pts. H.20, for 5-6 hours, the loss by evaporation be- ing made up from time to time. Mercuric Nitrate— Hg(NOa),2—323.7—is formed when Hg or HgO is dissolved in excess of HNOa, and the solution evaporated at a gentle heat. A syrupy liquid is obtained, which, over quick-lime, deposits large, deliquescent crystals, having the composition 2[Hg(NO.;)J -t- Aq, while there remains an unerystallizable liquid, Hg(NO.,)2 4- 2 Aq. This salt is soluble in H.,0, and exists in the Liq. hydrargyri nitratis (U. S.), Liq. hydrargyri nitratis acid us (Br.) ; in the volumetric standard solution used in Liebig's process for urea ; and probably in citrine ointment — Ung. hydrar. nitratis (U. S.; Br.). Dimercuric Nitrate —Hg(NOs)a, HgO + Aq —539.4—is formed when HgO is dissolved to saturation in hot HNOr, diluted with 1 vol. H,0 ; and crvstallizes on cooling. It is decomposed by H,0 into trimercuric nitrate, Hg;NO.,),, 2HgO, and Hg(N03).2. Hexamercuric Nitrate— Hg(NOs)a, 5HgO —1402.2—is formed as a red powder, by the action of H.,0 on trimercuric nitrate. Sulphates. —Mercurous Sulphate— (Hg2)SO 4—495.4—is a white, crys- talline powder, formed by gently heating together 2 pts. Hg and 3 pts. H2S04, and causing the product to combine with 2 pts. Hg. Heated with NaCl it forms (Hg2)Cl2. Mercuric Sulphate—Hydrargyri sulphas (Br.)—HgS04—295.7—is ob- tained by heating together Hg and H,2S04; or Hg, H2S04, and HN03. It is a white, crystalline, anhydrous powder, which on contact with H.,0 is decomposed with formation of trimercuric sulphate, HgS04, 2HgO ; a yel- low, insoluble powder known as turpeth mineral — Hydrargyri subsulphas Jlavus (V. S.). Analytical Characters Mercurous.—(1.) Hydrochloric acid : white ppt.; insoluble in H.,0 and in acids ; turns black with NH4HO ; when boiled with HC1, deposits Hg, while HgCl, dissolves. (2.) Hydrogen sulphide: black ppt.; insoluble in alkaline sulphy- drates, in dilute acids, and in KCN ; partly soluble in boiling HN03. (3.) Potash : black ppt.; insoluble in excess. (4.) Potassium iodide: greenish ppt.; converted by excess into Hg which is deposited, and Hgl2, which dissolves. Mercuric.—(1.) Hydrogen sulphide: black ppt. If the reagent be slowly added, the ppt. is first white, then orange, finally black. (2.) Ammonium sulpliydrate : black ppt.; insoluble in excess, except in the presence of organic matter. (3.) Potash or soda: yellow ppt.; insoluble in excess. ACTION ON THE ECONOMY. 167 (4.) Ammonium hydrate: white ppt.; soluble in great excess and in solutions of NH4 salts. (5.) Potassium carbonate : red ppt. (6.) Potassium iodide: yellow ppt., rapidly turning to salmon color, then to red ; easily soluble in excess of KI, or in great excess of mercuric salt. (7.) Stannous chloride, in small quantity : white ppt.; in larger quan- tity gray ppt.; and when boiled, deposit of globules of Hg. Action on the Economy. Mercury, in the metallic form, is without action upon the animal econ- omy so long as it remains such ; on contact, however, with alkaline chlo- rides it is converted into a soluble double chloride, and this the more read- ily the greater the degree of subdivision of the metal. The mercurials insoluble in dilute HC1 are also inert until they are converted into soluble compounds. Mercuric chloride, a substance into which many other compounds of Hg are converted when taken into the stomach or applied to the skin, not only has a distinctly corrosive action, by virtue of its tendency to unite with albuminoids, but when absorbed it produces well-marked poisonous effects, somewhat similar to those of arsenical poisoning ; indeed, owing to its corrosive action and to its greater solubility, and more rapid absorp- tion, it is a more dangerous poison than As„Os. In poisoning by HgCl„ the symptoms begin sooner after the ingestion of the poison than in arsen- ical poisoning, and those phenomena referable to the local action of the toxic are more intense. The treatment should consist in the administration of white of egg, not in too great quantity, and the removal of the compound formed, by emesis, before it has had time to redissolve in the alkaline chlorides contained in the stomach. Absorbed Hg tends to remain in the system in combination with albu- minoids, from which it may be set free, or, more properly, brought into soluble combination, at a period quite removed from the date of last ad- ministration, by the exhibition of alkaline iodides. Mercury is eliminated principally by the saliva and urine, in which it may be readily detected. The fluid is faintly acidulated with HC1, and in it is immersed a short bar of Zn, around which a spiral of dentist’s gold- foil is wound in such a way as to expose alternate surfaces of Zn and Au. After 24 hours, if the saliva or urine contain Hg, the Au will be whitened by amalgamation ; and, if dried and heated in the closed end of a small glass tube, will give off Hg, which condenses in globules, visible with the aid of a magnifier, in the cold part of the tube. MANUAL OF CHEMISTRY. COMPOUNDS OF CARBON. Organic Substances. In the seventeenth and eighteenth centuries, chemists had observed that there might be extracted from animal and vegetable bodies substances which differed much in their properties from those which could be ob- tained from the mineral world ; substances which burned without leav- ing a residue, and many of which were subject to the peculiar changes wrought by the processes of fermentation and putrefaction. It was not until the beginning of the present century, however, that chemistry Avas divided into the two sections of inorganic and organic. In the latter class were included all such substances as existed only in the organized bodies of animals and vegetables, and which seemed to be of a different essence from that of mineral bodies, as chemists had been unable to produce any of these organic substances by artificial means. Later in the history of the science it Avas found that these bodies were all made up of a very few elements, and that they all contained carbon. Gmelin at this time proposed to consider as organic substances all such as contained more than one atom of C, his object in thus limiting the mini- mum number of atoms of C being that substances containing one atom of C, such as carbonic acid and marsh-gas, were formed in the mineral king- dom, and consequently, according to then existing vieAvs, could not be con- sidered as organic. Illogical as such a distinction is, Ave find it still adhered to in text-books of very recent date. The notion that organic substances could only be formed by some mys- terious agency, manifested only in organized beings, Avas finally exploded by the labors of Wohler and Kolbe. The former obtained urea from am- monium cyanate ; AAdiile the latter, at a subsequent period, formed acetic acid, using in its preparation only such unmistakably mineral substances as coal, sulphur, aqua regia, and Avater. During the half-century folloAving Wohler’s first synthesis, chemists have succeeded not only in making from mineral materials many of the substances previously only formed in the laboratory of nature, but have also produced a vast number of carbon compounds which Avere previously unknoAvn, and which, so far as Ave knoAA7, liaATe no existence in nature. At the present time, therefor, ice must consider as an organic substance any compound containing carbon, ichatever may be its origin and whatever its properties. Indeed, the name organic is retained merely as a matter of convenience, and not in any way as indicating the origin of these com- pounds. Although, OAA'ing to the great number of the carbon compounds, it is still convenient to treat of them as forming a section by themselves, their relations Avith the compounds of other elements is frequently very close ; indeed, within the past feAV years, compounds of silicon have been obtained, which indicate the possibility that that element is capable of forming series of compounds as interesting in numbers and variety as those of carbon. Nevertheless, there are certain peculiarities exhibited by C in its com- pounds, which are not possessed to a like extent by any other element, HOMOLOGOUS SERIES. 169 and which render the study of organic substances peculiarly interesting and profitable. In the study of the compounds of the other elements, we have to deal with a small number of substances, relatively speaking, formed by the union with each other of a large number of elements. With the organic substances the reverse is the case; for, although compounds have been formed which contain C along with each of the other elements, the great majority of the organic substances are made up of C, combined with a very few other elements ; H, O and N occurring in them most frequently. It is chiefly in the study of the carbon compounds that we have to deal with radicals (see p. 23). Among mineral substances there are many whose molecules consist simply of a combination of two atoms; among organic substances there is none which does not contain a radical: indeed, organic chemistry has been defined as “the chemistry of compound radicals.” The atoms of carbon possess in a higher degree than those of any other element the power of uniting with each other, and in so doing of inter- changing valences. Were it not for this property of the C atoms, we could have but one saturated compound of carbon and hydrogen, CH4, or, expressed graphically: H H—C—H I H There exist, however, a great number of such compounds, which differ from each other by one atom of C and two atoms of H. In these substances the atoms of C may be considered as linked together in a continuous chain, their free valences being satisfied by H atoms ; thus: H I H—C—H I H H H I I H—C—C-H I I H H H H H H I I I I H—C—C—C—C— H III! H H H H If now one H atom be removed from either of these combinations, we have a group possessing one free valence, and consequently univalent. The decompositions of these substances show that they contain such radicals, and that their typical formula are : CH ) . H f 5 an, i . H ) ’ C4H) H f* Homologous Series. It will be observed that these formula differ from each other by CH2, or some multiple of CH„ more or less. In examining numbers of organic substances, which are closely related to each other in their properties, we find that we can arrange the great majority of them in series, each term of which differs from the one below it by CH, ; such a series is called an 170 MANUAL OF CHEMISTRY. homologous series. It will be readily understood that such an arrange- ment in series vastly facilitates the remembering of the composition of organic bodies. In the following table, for example, are given the satu- rated hydrocarbons and their more immediate derivatives. At the head of each vertical column is an algebraic formula, which is the general formula of the entire series below it; n being equal to the numerical position in the series. Homologous Seeies. pppppppppppppo eo*o»o»oto©aDO»rf-to© © ao o> .**■ to Saturated hydro- carbons, CnHan+jj. •••• OOOQOOOO^O B* t> ::::^kksswksk* Wo to o ::::^bbobbb®®° 4* o 5* n> :::::: wwwbwww: W * to cr og- CO CV O- O^OOOOOQQfl ;o: b- bPPPPpbbp? 3 > »a pH- pH- pjMWMKKSKWo *g O- op °W P$ But the arrangement in homologous series does more for us than this. The properties of substances in the same series vary in regular gradation according to their position in the series ; thus, in the series of alcohols in the above table, the boiling-points of the first six are, 66.5.°, 78.4°, 96.7°, 111.7°, 132.2°, 153.9° ; from which it will be seen that the boiling-point of any one of them can be determined, with a maximum error of 3°, by taking the mean of those of its neighbors above and below. In this way we may prophecy, to some extent, the properties of a wanting member in a series before its discovery. The terms of any homologous series must all have the same constitution, i.e., their constituent atoms must be sim- ilarly arranged within the molecule. Isomerism—Metamerism—Polymerism. Two substances are said to be isomeric, or to be isomeres of each other, when they have the same centesimal composition. If, for instance, we analyze acetic acid and methyl formiate, we find that each body consists of C, O and H, in the following proportions : Carbon 40 Oxygen 53.33 Hydrogen 6.67 100.00 24 = 12 x 2 32 = 16 x 2 4=1x4 60 CLASSIFICATION OF ORGANIC SUBSTANCES. 171 This similarity of centesimal composition may occur in two ways: the two substances may each contain in a molecule the same numbers of each kind of atom ; or one may contain in each molecule the same kind of atoms as the other, but in a higher multiple. In the above instance, for example, each substance may have the composition C.,H(03; or one may have that formula and the other, C6H1206, or x 3. In the former case the substances are said to be metameric, in the latter polymeric. Whether two substances are metameric or polymeric can only be determined by ascer- taining the weights of their molecules, which is usually accomplished by determining the sp. gr. of their vapors (see p. 14). The sp. gr. of the vapor of acetic acid is the same as that of methyl formiate, and, consequently, each substance is made up of molecules, each containing C ,H402. But the two substances differ from each other greatly in their properties, and their differences are at once indicated by their typical or graphic formulae : (C2H30)' 1 0 H » u and (CHO)') Q. or graphically : ch3 COOH H I cooch3. and Classification of Organic Substances. As the compounds of the other elements may be divided into classes, such as acids, bases, salts, etc., according to their chemical functions, the compounds of carbon also arrange themselves into certain well-defined groups, called by the French chemists functions—a term which it would be well to introduce into our own nomenclature. The properties of the functions of organic substances do not depend, like those of other com- pounds, upon the kind of atoms of which they are composed, but rather upon the arrangement of the atoms within the molecule ; and in this point we find the most prominent distinction between organic and mineral sub- stances. Arsenic, for instance, is poisonous in whatever form of chemical combination it may be, provided only that it can be rendered soluble, and therefor capable of absorption. Carbon, oxygen, and hydrogen, on the other hand, combine with each other to form substances having the most diverse action upon the economy—the fats and sugars, ordinary articles of food, on the one hand, and substances having such marked toxic powers as ether and oxalic acid, on the other—the differences between the prop- erties of the two substances depending entirely upon the numbers and positions in the molecule of the same kind of atoms. 172 MANUAL OF CHEMISTRY. SATURATED HYDROCARBONS AND THEIR DERIVATIVES. FIRST SERIES OF HYDROCARBONS Series C„H.„ + s. A hydrocarbon is a compound of carbon and hydrogen only. It is satu- rated when all the valences of all the constituent atoms are satisfied. The hydrocarbons of this series at present known are the following : Name. Formula. Specific gravity of liquid. Boiling- ! point. Cen- tigrade. Name. | Specific Formula, gravity of liquid. Boiling- point.Cen- tigrade. CH3H CyH](4H 0.741 at 18° 136°-138° c2h6h C10H21H 0.757 at 18° 158°-162° Propyl hydride... c3h7h Undecyl hydride. CnFI23H 0.766 at 18° 180°-182° Butyl hydride o4h9h 0.600 at 0° 0° Hodecyl hydride. C,2H 0.778 at 18° 198°-200° Amyl hydride C5HuH 0.628 at 18° 30° Tridecvl hydride. C13H2-H 0.796 at 18° 218° 220° Hexyl hydride ... c6hi3h 0.669 at 18° 68° Tetradecyl hydride C14H29H 0.809 at 18° 236°-240° Heptyl hydride CtI115II 0.690 at 18° 92°-94° Pentadecvlhydride Ci51131H 0.825 at 18° 258°-262° Octyl hydride .... 0.726 at 18° 116°-118:> Hexadecyl hydride C16H33H about 280° They form an homologous series whose general formula is +«, and are known as paraffines from their stability (parum = little, affinis = affinity). Their constitution is expressed typically by the formula C H ) 1 H j * ie radicah CnH2„ + i, of which they are the hydrides, are designated as the radicals of the monoatomic alcohols. Corresponding to the higher terms of the series (those above the third) there are one or more isomeres, which may be arranged in four classes. (1.) The normal or regularly formed series, in which each C atom is linked to two other C atoms. (2.) Those in which one C atom is linked to three others. (3.) Those in which two C atoms are each linked to three others. (4.) Those in which one C atom is linked to four others. The constitution of these series is explained by the graphic formulae : (1.) CHa I CH„ I CH, ch2 ch2 ch3 06h14 (2.) ch3 I H—C- CH3 I CH, ch2 I ch3 c,h14 (3.) CHS H-C—CH3 I H—C—CH3 I ch3 C6H14 (M CH3 I H3C —C—CH3 I CHa I CH3 c6h14 As all of these compounds are saturated they are incapable of being modified by addition, i.e. by the simple insertion of other atoms into the FIRST SERIES OF HYDROCARBONS. 173 molecule; they may, however, be modified by substitution, i.e. by the re- moval of one or more of their atoms and the substitution therefor of an atom qr atoms of different kind. Methyl hydride—Methane—Marsh-gas—Light carburetted hydrogen— Fire-damp—CHi—16—is given off in swamps as a product of decomposi- tion of vegetable matter, in coal mines, and in the gases issuing from the earth in the vicinity of petroleum deposits. Coal-gas contains it in the proportion of 36-50 per cent. It may be prepared by strongly heat- ing a mixture of sodium acetate with sodium hydrate and quicklime. It is a colorless, odorless, tasteless gas ; very sparingly soluble in II„0 ; sp. gr. 0.559A. At high temperatures it is decomposed into C and II. It burns in air with a pale yellow flame. Mixed with air or O it explodes violently on contact with flame, px-oducing water and carbon dioxide ; the latter constituting the after-damp of miners. It is not affected by Cl in the dark, but under the influence of diffuse daylight one or more of the II atoms are displaced by an equivalent quantity of Cl. In direct sunlight the substitution is accompanied by an explosion. Petroleum.—Crude petroleum differs in composition and in physical properties in the products of different wells, even in the same section of country. It varies in color from a faintly yellowish tinge to a dark brown, nearly black, with greenish reflections. The lighter-colored varie- ties are limpid, and the more highly colored of the consistency of thin syrup. The sp. gr. varies from 0.74 to 0.92. Crude petroleums contain all the hydrocarbons mentioned in the list on p. 172 (the first of the series, being found in the gases accompanying petroleum, is also held in solution by the oil under the pressure it supports in natural pockets), be- sides hydrocarbons of the olefine series, and of the benzol series. The crude oil is highly inflammable, usually highly colored, and is pre- pared for its multitudinous uses in the arts by the processes of distillation and refining. The distillation is usually so conducted as to divide the pi'oduct into four parts: Naphtha Sn. gr. 0.730—12-15 Benzine Sp. gr. 0.730— 9-12,; Burning oil Sp. gr. 0.7S3—60% Residuum and loss 13-1 % The naphtha, or petroleum ether, is further separated by distillation into other products : Rh igoline, a highly inflammable liquid; sp. gr. about 0.60, which boils at about 213 (7CF F.). It is used to produce cold by its rapid evaporation, but its low boiling-point and inflammability render its use dangerous. Gasoline; sp. gr. about 0.63-0.61; boils at about 76° (170° F.). Benzine or benzoline, sp. gr. about 0.73 ; boils at about 148° (298° F.), and is largely used in the art3 as a solvent. It must not be confounded with benzol or benzene, CcHR* (q. v.). The most important product of petroleum is that portion which distils above 1833 (361° F.) and which constitutes kerosene, and other oils used for burning in lamps. An oil to be safely used for burning in lamps should not “flash,” or give off inflammable vapor, below 60° (140° F.); and should not burn at temperatures below 65°.5 (150° F.). From the residue remaining after the separation of the kerosene, a variety of other products are obtained. Lubricating oils, of too high boil- ing-point for use in lamps. Paraffine, a white, crystalline solid, fusible at 45°-65° (113°-149° F.), which is used in the arts for a variety of pur- poses formerly served by wax, such as the manufacture of candles. In the laboratory it is very useful for coating the glass stoppers of bottles, and for 174 MANUAL OF CHEMISTRY. other purposes, as it is not affected by acids or by alkalies. It is odorless, tasteless, insoluble in H„0 and in cold alcohol; soluble in boiling alcohol and in ether, fatty and volatile oils, and mineral oils. It is also obtained by the distillation of certain varieties of coal, and is found in nature in fossil wax or ozocerite. The products known as vaseline, petrolatum (U. S.), cosmoline, etc., which are now so largely used in pharmacy and perfumery, are mixtures of paraffine and the heavier petroleum oils. Like petroleum itself, its various commercial derivatives are not definite compounds, but mixtures of the hydrocarbons of this series. Haloid Derivatives of the Paraffines. By the action of Br upon the paraffines, or by the action of HC1, HBr or HI upon the corresponding hydrates, compounds are obtained in which one of the H atoms of the hydrocarbon has been replaced by an atom of Cl, Br or I: C2H8 + Br„ — C,H.Br + HBr, or C2H6OH + HC1 = C..H.C1 + H.,0. These compounds may be considered as the chlorides, bromides or iodides of the alcoholic radicals ; and are known as haloid ethers. When Cl is allowed to act upon CH,, it replaces a further number of H atoms until finally carbon tetrachloride, CC14, is produced. Consider- ing marsh gas as methyl hydride, CH;t,H, the first product of substitution is methyl chloride, CH3,C1; the second monochlormethyl chloride, CH2C1, Cl ; the third dichlormethyl chloride, or chloroform, CHC12C1; and the fourth carbon tetrachloride, CC14. Similar derivatives are formed with Br and I and with the other hydro- carbons of the series. Methyl chloride—CHsCl—50.5—is a colorless gas, slightly solu- ble in H„0, and having a sweetish taste and odor. It is obtained by dis- tilling together H„S04, sodium chloride and methyl acliohol. It may be condensed to a liquid which boils at —22 (— 7 .6F.). It burns with a greenish flame. Heated with potassium hydrate it is converted into methyl alcohol. Monochlormethyl chloride—Methene chloride—Dichloromethane— Methylene chloride—Chloromethyl—CH.Cl.Cl—85—is obtained by the action of Cl upon CH3C1; or by shaking an alcoholic solution of chloro- form with powdered zinc and a little ammonium hydrate. In either case the product must be purified. It is a colorless, oily liquid, boils at 40 -42 (104 -107°.6 F.) ; sp. gr. 1.36 ; its odor is similar to that of chloroform ; it is very slightly soluble in H.,0 ; and is not inflammable. Like most of the chlorinated derivatives of this series, it is possessed of anaesthetic powers. Its use as an anaes- thetic is attended with the same (if not greater) danger as that of chloro- form. Dichlormethyl chloride—Methenyl chloride—Formyl chloride— Trichloromethane—Chloroform—Chloroformum (U. S., Br.)—CHC1„,C1— 120.5—is obtained by heating in a capacious still, 35-40 litres (9-11 gall.) of H.,0, adding 5 kilos (11 lbs.) of recently slacked lime and 10 kilos (22 lbs.) of chloride of lime ; 2.5 kilos (24 qts.) of alcohol are then added and the temperature quickly raised until the product begins to distil, when the fire is withdrawn, heat being again applied toward the end of the reaction. The crude chloroform so obtained is purified, first by agitation 175 HALOID DERIVATIVES OF TIIK PARAFFINES with H SO then by mixing with alcohol and recently ignited potassium carbonate, and distilling the mixture. It is a colorless, volatile liquid, having a strong, agreeable, ethereal odor, and a sweet taste ; sp. gr. 1.497 ; very sparingly soluble in H.,0; miscible with alcohol and ether in all proportions ; boils at 60°.8 (141°.4 F.). It is a good solvent for many substances insoluble in H.,0, such as phos- phorus, iodine, fats, resins, caoutchouc, gutta-percha and the alkaloids. It ignites with difficulty, but burns from a wick with a smoky, red flame, bordered with green. It is not acted on by H. ,S04, except after long contact, when HC1 is given oft'. In direct sunlight Cl converts it into OC1, and HC1. The alkalies in aqueous solution do not act upon it, but when heated with them in alcoholic solution it is decomposed with formation of chloride and formiate of the alkaline metal. When perfectly pure it is not altered by exposure to light; but if it contain compounds of X, even in very minute quantity, it is gradually decomposed by solar action into HC1, Cl and other substances. Impurities.—Alcohol, if present in large amount, lowers the sp. gr. of the chloroform, and causes it to fall through H .O in opaque, pearly drops. If present in small amount it produces a green color with ferrous dinitrosul- phide (obtained by acting on ferrous chloride with a mixture of potassium nitrate and ammonium hydrosulphide). Aldehyde produces a brown color when CHC13 containing it is heated with liquor potassae. Hydrochloric acid reddens blue litmus, and causes a white precipitate in an aqueous solution of silver nitrate shaken with chloroform. Methyl and empyreu- matic compounds are the most dangerous of the impurities of chloroform. Their absence is recognized by the following characters : (1.) When the chloroform is shaken with an equal volume of colorless H S04, and allowed to stand 24 hours ; the upper (chloroform) layer should be perfectly color- less, and the lower (acid) layer colorless or faintly yellow. (2.) When a small quantity is allowed to evaporate spontaneously, the last portions should have no pungent odor, and the remaining film of moisture should have no taste or odor other than those of chloroform. Analytical Characters.—(1.) Add a little alcoholic solution ot potash and 2-3 drops of aniline and warm ; a disagreeeble odor, resembling that of witch-hazel, is produced. (2.) Vapor of CHC1„, when passed through a red-hot tube, is decom- posed with formation of HC1 and Cl, the former of which is recognized by the production of a white ppt., soluble in ammonium hydrate, in an acid solution of silver nitrate. This test does not afford reliable results when the substance tested contains a free acid and chlorides. (3.) Dissolve about 0.01 Gm. of /3 naphthol in a small quantity of KHO solution, warm, and add the suspected liquid ; a blue color is pro- duced. Toxicology.—The action of chloroform varies as it is taken by the stomach or by inhalation. In the former case, owing to its insolubility, but little is absorbed, and the 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. Chloro- form vapor acts much more energetically, and seems to owe its potency for evil to its paralyzing influence upon the nerve-centres, notably upon those of the heart. While persons suffering from heart disease are particu- larly susceptible to the paralyzing effect of chloroform vapor, there are many cases recorded of death from the inhalation of small quantities, properly diluted, in which no heart lesion was found upon a jiost-mortem examina- 176 MANUAL OF CHEMISTRY tion. Chloroform is apparently not altered in the system, and is elimi- nated with the expired air. No chemical antidote to chloroform is known. When it has been swallowed, the stomach-pump and emetics are indicated ; when taken by inhalation, a free circulation of air should be established about the face ; artificial respiration and the application of the induced current to the sides of the neck should be resorted to. The nature of the poison is usually revealed at the autopsy by its peculiar odor, which is most noticeable on opening the cranial and tho- racic cavities. In a toxicological analysis, chloroform is to be sought for especially in the lungs and blood. These are placed in a flask ; if acid, neutralized with sodium carbonate ; and subjected to distillation at the temperature of the water-batli. The vapors are passed through a tube of difficultly fusible glass ; at first the tube is heated to redness for about an inch of its length, and test No. 2 applied to the issuing gas. The tube is then allowed to cool, and the distillate collected in a pointed tube, from the point of which any CHC13 is removed by a pipette and tested according to Nos. 1 and 3 above. Carbon tetrachloride—Chlorocarbon—CC14—154—is formed by the prolonged action, in sunlight, of Cl upon CH3C1 or CHC13; or more rapidly, by passing Cl, charged with vapor of carbon disulphide, through a red-hot tube, and purifying the product. It is a colorless, oily liquid, insoluble in 1I20 ; soluble in alcohol and in ether; sp. gr. 1.56 ; boils at 78° (172°.4 F.). Its vapor is decomposed at a red heat into a mixture of the dichloride, C2C14, trichloride, C2C1|;, and free Cl. Methyl bromide—CH.Br—95.—A colorless liquid ; sp. gr. 1.664 ; boils at 13° (55.4° F.); formed by the combined action of P and Br on methyl hydrate. Dibromomethyl bromide—Methenyl bromide—Formyl bromide— Bromoform—CHBr,, Br—-253—is prepared by gradually adding Br to a cold solution of potassium hydrate in methyl alcohol, until the liquid begins to be colored ; and rectifying over calcium chloride. A colorless, aromatic, sweet liquid ; sp. gr. 2.13 ; boils at 150°-152° (302°-306° F.); solidifies at —9° (15°.8 F.); sparingly soluble in H„0 ; soluble in alcohol and ether. Boiled with alcoholic potash it is decom- posed in the same way as is CHC1... Its physiological action is similar to that of CHC13. It occurs as an impurity of commercial Br, accompanied by carbon tetrabromide, CBr4. Methyl iodide—CH I—142—a colorless liquid, sp. gr. 2.237 ; boils at 45° (113° F.) ; burns with difficulty, producing violet vapor of iodine. It is prepared by a process similar to that for obtaining the bromide ; and is used in the aniline industry. Diiodomethyl iodide—Methenyl iodide—Formyl iodide—Iodoform— Iodoformum, U S.—CHI I—394.—Formed, like chloroform and bromoform, by the combined action of potash and the halogen upon alcohol; it is also produced by the action of I upon a great number of organic substances, and is usually prepared by heating a mixture of alkaline carbonate, H O, I and etliylic alcohol, and purifying- the product by recrystallization from alcohol. Iodoform is a solid, crystallizing in yellow, hexagonal plates, which melt at 115°-120° (239°-248° F.). It maybe sublimed, a portion being decomposed. It is insoluble in water, acids, and alkaline solutions : solu- ble in alcohol, ether, carbon disulphide, and the fatty and essential oils: MONOATOMIC ALCOHOLS. 177 the solutions, when exposed to the light, undergo decomposition and assume a violet-red color. It has a sweet taste and a peculiar, penetrating odor, resembling, when the vapor is largely diluted with air, that of saffron. When heated with potash, a portion is decomposed into formiate and iodide, while another portion is carried off unaltered with the aqueous vapor. It contains 96.7$ of its weight of iodine. Ethyl chloride—Hydrochloric or muriatic ether—C.H Cl—64.5.—A colorless, white, ethereal liquid ; boils at 11° (51°.8 F.) ; obtained by passing gaseous HC1 through ethylic alcohol to saturation and distilling over the water-bath. Ethyl bromide — Hydrobromic ether—C„H Br—109.—A colorless, ethereal liquid; boils at 40°.7 (105°.3 F.); obtained by the combined action of P and Br on ethylic alcohol. Ethyl iodide—Hydriodic ether—CHI—156—is prepared by placing absolute alcohol and P in a vessel surrounded by a freezing mixture and gradually adding I; when the action has ceased, the liquid is decanted, distilled over the water-bath, and the distillate washed and rectified. It is a colorless liquid ; boils at 72°.2 (162° F.) ; has a powerful, ethereal odor ; burns with difficulty. It is largely used in the aniline industry. MONOATOMIC ALCOHOLS. Series C„H,„ + iO. The following is a list of the terms of the primary series which have been studied, and their prominent physical properties. Name. Empirical formula. Typical formula. Fusing- point. Boiling- point. Specific gravity. Methyl hydrate ch4o ch3 H 1 f 0 . . 66°.5 0 814 Ethyl hydrate CjHtfO c3h3 H ) f 0 78°.3 0 8095 Propyl hydrate c3h*o C3H, H 1 1 0 9(3°.7 0 820 Butyl hydrate C4H10O C4H3 H ) i 0 114°.7 0 817 Amyl hydrate c6h12o c,hm H 1 f 0 -20° 132° Hexyl hydrate C„HuO c8h13 H } f 0 150° 0 820 Heptyl hydrate c7h16o c7h15 H ) f 0 • • 168° Octyl hydrate CjHj 8o c8h17 H } 0 h> 00 rH Nonyl hydrate CaHioO C9H1B H ) r 0 204° Decyl hydrate CioH220 C.oHg, H \ 0 Cetyl hydrate c16h34o Oi8H33 H > y 0 49° Ceryl hydrate c27h5Bo c27h53 H i y 0 79° Myricyl hydrate C3oH820 C3oil6i H i y 0 85° 178 MANUAL OF CHEMISTRY. The name alcohol, formerly applied only to the substance now pop- ularly so called, has gradually come to be used to designate a' large class of important bodies, of which vinic alcohol is the representative. These substances are mainly characterized by their power of entering into double decomposition with acids, to form neutral compounds, called com- pound ethers, water being at the same time formed, at the expense of both alcohol and acid. They are the hydrates of hydrocarbon radicals, and as such resemble the metallic hydrates, while the compound ethers are the coun- ter parts of the metallic salts : (C2H5) ) 0 (C2H30) } 0 _ (C2H30)) o 4- H i o II } + H ju- (C2H j j u + II J u Ethyl hydrate. Acetic acid. Ethyl acetate. Water. |j}o+(W)}o=(cAO)}0,+ |j}o Potassium hydrate. Acetic acid. Potassium acetate. Water. As the metallic hydrates may be considered as formed by the union of one atom of the metallic element with a number of groups OH', corre- sponding to its valence, so the alcohols are formed by union of an unoxi- dized radical with a number of groups OH', equal to or less than the num- ber of free valences of the radical. When the alcohol contains one Oil, it is designated as monoatomic; when two, diatomic; when three, tri- atornic, etc. The simplest alcohols are those of this series derivable from the saturated hydrocarbons, and having the general formula C,JI2„+20, or C„H3„+iOH. They may be formed synthetically : (1.) By acting upon the corresponding iodide with potassium hydrate : C2II5I -f- KHO = KI + C,H. OH. (2.) From the alcohol next below it in the series, by direct addi- tion of CII„, only, however, by a succession of five reactions. (3.) By the action of H2S04 and I120 upon the corresponding hydrocarbon of the se- ries CnH2„. The saturated monoatomic alcohols are, however, not limited to one corresponding to each alcoholic radical. There exist—corresponding to the higher alcohols—a number of substances having the same centesimal com- position and the same alcoholic properties, but differing in their physical characters and in their products of decomposition and oxidation. These isoineres have been the subject of much careful study of late years. It has been found that the molecules of methyl, ethyl, and other higher alco- hols are made up of the group (CH„OH)' united to H or to C„H2„+1, thus : ch2oii H CH OH I CH3 CHsOH I c2h& Methyl alcohol. Ethyl alcohol Propyl alcohol. and all monoatomic alcohols containing this group, CH..OH, have been designated as primary alcohols. Isomeric with these are other bodies, MONO ATOMIC ALCOHOLS. 179 which, in place of the group (CH,OH)', contain the group (CHOH)", and are distinguished as secondary alcohols. Thus we have : (CHaOH)' I C2H5 csh8o ch3 (CHOH)" ch3 c3ho Primary propyl alcohol. Secondary propyl alcohol. And further, other isomeric substances are known which contain the group (COH)'", and which are called tertiary alcohols, thus : (CH„OH)' I c4h# c5h12o c2h5 I (CIIOH)" 1 c,h. c5h12o CHS (CaH.)—(COH)'" ch3 c5h12o Primary amylic alcohol. Secondary amylic alcohol. Tertiary amylic alcohol. The alcohols of these three classes are distinguished from each other principally by their products of oxidation. The primary alcohols yield by oxidation, first an aldehyde and then an acid, each containing the same num- ber of C atoms as the alcohol, and formed, the aldehyde by the removal of H, from the group (CH„OH), and the acid by the substitution of O for H, in the same group, thus: CHaOH I CH3 COH I ch3 COOH I ch3 Ethyl alcohol. Ethyl aldehyde. Acetic acid. In the case of the secondary alcohols, the first product of oxidation is a ketone, containing the same number of C atoms as the alcohol, and formed by the substitution of O for HOH in the distinguishing group : ch3 I CHOH I ch3 ch3 I CO I ch3 Secondary propyl alcohol. Propyl ketone or acetone. The tertiary alcohols yield by oxidation ketones or acids, whose molecules contain a less number of C atoms than the alcohol from which they are derived. But the complication does not end here ; isomeres exist corresponding to the higher alcohols, which are themselves primary alcohols, and contain the group (CH..OH)'. Thus there exist no less than seven distinct sub- 180 MANUAL OF CHEMISTRY. stances, all having the centesimal composition of amyl alcohol, C6H120, and the properties of alcohols; and theoretical considerations point to the probable existence of an eighth. Of these eight substances, four are pri- mary, three secondary alcohols, and the remaining one a tertiary alcohol. As each of these bodies contains the group of atoms characteristic of the class of alcohol to which it belongs, it is obvious that the differences ob- served in their properties are due to differences in the arrangement of the other atoms of the molecule. Experimental evidence, which it would require too much space to discuss in this place, has led chemists to ascribe the following formulae of constitution to these isomeres. Primary amylic alcohols: CH-CH—CH—CH-CH„OH Normal amylic alcohol. CH*/'H—CHa—CHa,OH Active amylic alcohol of fermentation. ch,Jh;/cii-ch”oh Inactive amylic alcohol of fermentation. CH8\ CH — C—CH2,OH CH,/ Unknown. Secondary amylic alcohols: CH3 CHs\sqjj QJJ CH,—CH— CH2/CH’0H Diethyl carbinol. Methyl-propyl carbinol. oh:^->h,oh Methyl-isopropyl carbinol. Tertiary amylic alcohol: CHS\ CH—C,OH CH,—CH,/ Methyl hydrate—Carbinol—Pyroxylic spirit—Wood spirit—CH HO —32—may be formed from marsh-gas, CH H, by first converting it into the iodide and acting upon this with potassium hydrate : CH3I -+- KHO = KI 4- It is usually obtained by the destructive distillation of wood. The crude wood vinegar so produced is a mixture of acetic acid and methyl alcohol with a variety of other products. The crude vinegar, separated from tarry products, is redistilled ; the first tenth of the distil- MONOATOMIC ALCOHOLS. 181 late is treated with quicklime and again distilled ; the distillate treated with dilute H.,S04; decanted and again distilled. The product, still quite impure, is the wood alcohol, wood naphtha, or pyroxylic spirit of commerce. The pure hydrate can only be obtained by decomposing a crystalline com- pound, such as methyl oxalate, and rectifying the product until the boiling- point is constant at 66°.5 (151°.7 F.). Pure methyl alcohol is a colorless liquid, having an ethereal and alco- holic odor, and a sharp, burning taste ; sp. gr. 0.814 at 0° ; boils at 66°.o (151°.7 F.) ; burns with a pale flame, giving less heat than that of ethylic alcohol ; mixes with water, alcohol, and ether in all proportions ; is a good solvent of resinous substances, and also dissolves sulphur, phosphorus, potash, and soda. Methyl hydrate is not affected by exposure to air under ordinary cir- cumstances, but in the presence of platinum-black it is oxidized, with for- mation of the corresponding aldehyde and acid, formic acid. Hot HNO, decomposes it with formation of nitrous fumes, formic acid and methyl nitrate. It is acted upon by H,S04 in the same way as ethyl alcohol. The organic acids form methyl ethers with it. With 1IC1 under the in- fluence of a galvailic current, it forms an oily substance having the com- position C,H3C10. Methylated spirit is ethyl alcohol containing suflicient wood spirit to render it unlit for the manufacture of ardent spirits, by reason of the dis- gusting odor and taste which crude wood alcohol owes to certain empy- reumatic products which it contains. Spirits so treated are not subject to the heavy duties imposed upon ordinary alcohol, and are, therefor, largely used in the arts and for the preservation of anatomical preparations. It contains one-ninth of its bulk of wood naphtha. Ethyl hydrate—Ethylic alcohol—Methyl carbinol—Vinic alcohol—Al- cohol—Spirits of wine—C H HO—46. Preparation.—Industrially alcohol and alcoholic liquids are obtained from substances rich in starch or glucose. The manufacture of alcohol consists of three distinct processes : 1st, the conversion of starch into sugar ; 2d, the fermentation of the saccharine liquid ; 3d, the separation, by distillation, of the alcohol formed by fer- mentation. The raw materials for the first process are malt and some sub- stance (grain, potatoes, rice, corn, etc.) containing starch. Malt is barley which has been allowed to germinate, and, at the proper stage of germina- tion, roasted. During this growth there is developed in the barley a peculiar nitrogenous principle called diastase. The starchy material is mixed with a suitable quantity of malt and water, and the mass maintained at a temperature of 65°-70J (149D-158° F.) for two to three hours, during which the diastase rapidly converts the starch into dextrin, and this in turn into glucose. The saccharine fluid, or ivort, obtained in the first process, is drawn off, cooled, and yeast is added. As a result of the growth of the yeast-plant, a complicated series of chemical changes take place, the principal one of which is the splitting up of the glucose into carbon dioxide and alcohol: C6Ii120? = 2C„H.OH + 2C02. There are formed at the same time small quantities of glycerin, succinic acid, and propyl, butyl, and amyl alcohols. An aqueous fluid is thus obtained which contains 3-15 per cent, of alcohol; this is then separated by the third process, that of distillation and rectification. The apparatus used for this purpose has been so far perfected that by a single distillation an alcohol of 90-95 per cent, can be obtained. 182 MANUAL OF CHEMISTRY. In some cases alcohol is prepared from fluids rich in glucose, such as grape-juice, molasses, syrup, etc. ; in such cases the first process becomes unnecessary. Commercial alcohol always contains H.,0, and when pure or absolute alcohol is required, the commercial product must be mixed with some hy- groscopic solid substance, such as quicklime, from which it is distilled after having remained in contact twenty-four hours. Fermentation.—This term, derived from fervere = to boil, was origi- nally applied to alcoholic fermentation, by reason of the bubbling of the saccharine liquid caused by the escape of C02 ; subsequently it came to be applied to all decompositions similarly attended by the escape of gas. At present it is used by many authors to apply to a number of hetero- geneous processes; and some writers distinguish between “true”•and “false” fermentation. It is best, we believe, to limit the application of the term to those decompositions designated as true fermentations. Fermentation is a decomposition of an organic substance, produced by the processes of nutrition of a low form of animal or vegetable life. The true ferments are therefor all organized beings, such as torula cere- visice, producing alcoholic fermentation ; penicillium glaucum, producing lactic acid fermentation ; and my coderma aceti, producing acetic acid fer- mentation. The false fermentations are not produced by an organized body, but by a soluble, unorganized, nitrogenous substance, whose method of action is as yet imperfectly understood. They may be, therefor, designated by the term cryptolysis. Diastase, pepsin and trypsin are cryptolytes. Properties.—Alcohol is a thin, colorless, transparent liquid, having a spirituous odor, and a sharp, burning taste; sp. gr. 0.8095 at 0°, 0.7939 at 15° (59° F.) ; it boils at 78°.5 (173°.3 F.), and has not been solidified ; at temperatures below —90° ( — 130° F.) it is viscous. It mixes with water in all proportions, the union being attended by elevation in temperature and contraction in volume (after cooling to the original temperature). It also attracts moisture from the air to such a degree that absolute alcohol only remains such for a very short time after its preparation. It is to this power of attracting I I„0 that alcohol owes its preservative power for animal substances. It is a very useful solvent, dissolving a number of gases, most of the mineral and organic acids and alkalies, most of the chlorides and carbonates, some of the nitrates, all the sulphates, essences, and resins. Alcoholic solutions of fixed medicinal substances are called tmctur'es ; those of volatile principles, spirits. The action of oxygen upon alcohol varies according to the conditions. Under the influence of energetic oxidants, such as chromic acid, or, when alcohol is burned in the air, the oxidation is rapid and complete, and is attended by the extrication of much heat, and the formation of carbon dioxide and water : C., HrO -f- 30,2 = 2CO„ 3H.20. Mixtures of air and vapor of alcohol explode upon contact with flame. If a less active oxidant be used, such as platinum-black, or by the action of atmospheric oxygen at low temperatures, a simple oxidation of the alcoholic radical takes place, with formation of acetic acid - | 0 + 02 = 2 jj j- O + H.,0, a reaction which is utilized in the manufacture of acetic acid and vinegar. If the oxidation be still further limited, aldehyde is formed : 2C.,HrO + 0., = 2C.,H40 + 2H„0. If vapor of alcohol be passed through a tube filled with platinum sponge and heated to redness, or if a coil of heated platinum wire be introduced into an atmosphere of alcohol vapor, the products of MONO ATOMIC ALCOHOLS. 183 oxidation are quite numerous : among tliem are water, ethylene, aldehyde, acetylene, carbon monoxide, and acetal. Heated platinum wire introduced into vapor of alcohol continues to glow by the heat resulting from the oxi- dation, a fact which has been utilized in the thermocautery. Chlorine and bromine act energetically upon alcohol, producing a num- ber of chlorinated and brominated derivatives, the final products being chloral and bromal (q. v.). If the action of Cl be moderated, aldehyde and HC1 are first produced. Iodine acts quite slowly in the cold, but old solu- tions of I in alcohol (tr. iodine) are found to contain HI, ethyl iodide, and other imperfectly studied products. In the presence of an alkali, I acts upon alcohol to produce iodoform. Potassium and sodium dissolve in alcohol with evolution of H ; upon cooling, a white solid crystallizes, wdiich is the double oxide of ethyl and the alkaline metal. Nitric acid, aided by a gentle heat, acts violently upon alcohol, producing nitrous ether, brown fumes, and products of oxidation. For the action of other acids upon alcohol see the corresponding ethers. The hydrates of the alkaline metals dissolve in alcohol, but react upon it slowly ; the solution turns brown and contains an acetate. If alcohol be gently heated with HN03 and nitrate of silver or of mercury, a gray precipitate falls, which is silver or mercury fulminate. Varieties.—It occurs in different degrees of concentration : absolute alcohol is pure alcohol, C.:HrO. It is not purchasable and must be made as required ; the so-called absolute alcohol of the shops is rarely stronger that 98 per cent. Alcohol (U. S.), sp. gr. 0.820, contains 94 per cent, by volume, and spiritus rectificatus (Br.), sp. gr. 0.838, contains 84 per cent. This is the ordinary rectified spirit used in the arts. Alcohol dilutum (U. S.) =Spmtus tenuior (Br.), sp. gr. 0.920, used in the preparation of tinctures, contains 53 per cent. It is of about the same strength as the proof spirit of commerce. Analytical Characters.—(1.) Heated with a small quantity of solution of potassium dichromate and H SO., the liquid assumes an emerald-green color, and if the quantity of C,HcO be not very small, the peculiar fruity odor of aldehyde is developed. (2.) Warmed and treated with a few drops of potash solution and a small quantity of iodine, an alcoholic liquid deposits a yellow, crystalline ppt. of iodoform, either immediately or after a time. (3.) If HN03 be added to a liquid containing C2H,.0, hitrous ether, recognizable by its odor, is given off. If a solution of mercurous nitrate with excess of HN03 be then added, and the mixture heated, a further evolu- tion of nitrous ether occurs, and a yellow-gray deposit of fulminating mer- cury is formed, which may be collected, washed, dried and exploded. (4.) If an alcoholic liquid be heated for a few moments with H2S04 di- luted with HsO and distilled, the distillate, on treatment with H2S04 and potassium permanganate, and afterward with sodium hyposulphite, yields aldehyde, which may be recognized by the production of a violet color with a dilute solution of fuchsin. None of the above reactions, taken singly, is characteristic of alcohol. Action on the Economy.—In a concentrated form, alcohol exerts a de- hydrating action upon animal tissues with which it comes in contact; causing coagulation of the albuminoid constituents. When diluted, ethylic alcohol may be a food, a medicine, or a poison, according to the dose and the condition of the person taking it. When taken in excessive doses, or in large doses for a long time, it produces symptoms and lesions characteristic of pure alcoholism, acute or chronic, modified or 184 MANUAL OF CHEMISTRY. aggravated by those produced by other substances, such as amyl alcohol, which accompany it in the alcoholic fluids used as beverages. Taken in moderate quantities, with food, it aids digestion and produces a sense of comfort and exhilaration. As a medicine it is the most valuable of stimulants. Much has been written concerning the value of alcohol as a food. If it have any value as such, it is as a producer of heat and force by its ox- idation in the body ; experiments have failed to show that more than a small percentage (16 per cent, in 24 lirs.) of medium doses of alcohol in- gested are eliminated by all channels ; the remainder, therefor, disappears in the body, as the idea that it can there “accumulate ” is entirely unten- able. That some part should be eliminated unchanged is to be expected from the rapid diffusion and the high volatility of alcohol. On the other hand, if alcohol be oxidized in the body, we should ex- pect, in the absence of violent muscular exercise, an increase in tempera- ture, and the appearance in the excreta of some product of oxidation of alcohol: aldehyde, acetic acid, carbon dioxide, or water, while the elimi- nation of nitrogenous excreta, urea, etc., would remain unaltered or be diminished. While there is no doubt that excessive doses of alcohol pro- duce a diminution of body temperature, the experimental evidence con- cerning the action in this direction of moderate doses is conflicting and incomplete. Of the products of oxidation, aldehyde has not been detected in the excreta, and acetic acid only in the intestinal canal. The elimi- nation of carbonic acid, as such, does not seem to be increased, although positive information upon this point is wanting. If acetic acid be pro- duced, this would form an acetate, which in turn would be oxidized to a carbonate, and eliminated as such by the urine. The elimination of water under the influence of large doses of alcohol is greater than at other times: but whether this water is produced by the oxidation of the hydrogen of the alcohol, or is removed from the tissues by its dehydrating action, is an open question. While physiological experiment yields only uncertain evidence, the experience of arctic travellers and others shows that the use of alcohol tends to diminish rather than increase the capacity to withstand cold. The experience of athletes and of military commanders is that intense and prolonged muscular exertion can be best performed without the use of alcohol. The experience of most literary men is that long-continued mental activity is more difficult with than without alcohol. In cases of acute poisoning by alcohol, the stomach-pump and catheter should be used as early as possible. A plentiful supply of air, the cold douche, and strong coffee are indicated. Alcoholic Beverages.—The variety of beverages in whose prepara- tion alcoholic fermentation plays an important part is very great, and the products differ from each other materially in their composition and in their physiological action. They may be divided into four classes, the classifi- cation being based upon the sources from which they are obtained and upon the method of tlieir preparation. I. —Those prepared by the fermentation of malted grain—beers, ales, and porters. II. —Those prepared by the fermentation of grape juice—wines. III. —Those prepared by the fermentation of the juices of fruits other than the grape—cider, fruit-wines. IV. —Those prepared by the distillation of some fermented saccharine liquid—ardent spirits. MONOATOMIC ALCOHOLS 185 Beer, - O— 5 j- O, and communicates to the radical electro-negative or acid qualities. Formic acid-HCO,OH—46—occurs in the acid secretion of red ants, in the stinging hairs of certain insects, in the blood, urine, bile, perspiration, and muscular fluid of man, in the stinging-nettle, and in the leaves of trees of the pine family. It is produced in a number of reactions ; by the oxidation of many organic substances: sugar, starch, fibrin, gelatin, albumin, etc. ; by the action of potash upon chloroform and kindred 192 MANUAL OF CHEMISTRY. bodies ; by the action of mineral acids in hydrocyanic acid; during the fermentation of diabetic urine ; by the direct union of carbon monoxide and water ; by the decomposition of oxalic acid under the influence of glycerin at about 100° (212° F.). It is a colorless liquid, having an acid taste and a penetrating odor ; it acts as a vesicant; it boils at 100 J (212° F.), and, when pure, crystallizes at 0° (32° F.). It is miscible with H„0 in all proportions. The mineral acids decompose it into H20 and carbon monoxide. Oxidiz- ing agents convert it into H20 and carbon dioxide. Alkaline hydrates decompose it with formation of a carbonate and liberation of H. It acts as a reducing agent with the salts of the noble metals. Acetic acid—Acetyl hydrate—Hydrogen acetate—Pyroligneous acid— Acidum aceticum (U. S.; Br.)—CH3CO,OH—60. Formation.—(1.) By the oxidation of alcohol: ch3ch2,oh + o2 = ch3co,oh + h2o. (2.) By the dry distillation of wood. (3.) By the decomposition of natural acetates by mineral acids. (4.) By the action of potash in fusion on sugar, starch, oxalic, tartaric, citric acids, etc. (5.) By the decomposition of gelatin, fibrin, casein, etc., by H2S04 and manganese dioxide. (6.) By the action of carbon dioxide upon sodium methyl: CO„ 4- Na CH3 — C2H302Na ; and decomposition of the sodium acetate so produced. The acetic acid used in the arts and in pharmacy is prepared by the destructive distillation of wood. The products of the distillation, which vary with the nature of the wood used, are numerous. Charcoal remains in the retort, while the distilled product consists of an acid, watery liquid ; a tarry material ; and gaseous products. The gases are carbon dioxide, carbon monoxide, and hydrocarbons ; they are sometimes used for illu- minating purposes, but are usually directed into the furnace, where they serve as fuel. The tar is a mixture of empyreumatic oils, hydrocarbons, phenol, oxyphenol, acetic acid, ammonium acetate, etc. The acid water is very complex, and contains, besides acetic acid, formic, propionic, butyric, valerianic, and oxyphenic acids, acetone, naph- thalene, benzene, toluene, cumene, creasote, methyl alcohol, and methyl acetate, etc. Partially freed from tar by decantation, it still contains about 20 per cent, of tarry and oily material, and about 4 per cent, of acetic acid ; this is the crude pyroligneous acid of commerce. The crude product is subjected to a first purification by distillation ; the first portions are collected separately and yield methyl alcohol (q. v.) ; the remainder of the distillate is the distilled pyroligneous acid, used to a limited extent as an antiseptic, but principally for the manufacture of acetic acid and the acetates. It can only be freed from the impurities which it still contains by chemical means ; to this end slacked lime and chalk are added, at a gentle heat, to neutralization ; the liquid is boiled and allowed to settle twenty-four hours ; the clear liquid, which is a solu- tion of calcium acetate, is decanted and evaporated ; the calcium salt is converted into sodium acetate, which is then purified by calcination at a temperature below 330° (626° F.), dissolved, filtered, and recrystallized ; the salt is then decomposed by a proper quantity of H4S04, and the liber- ated acetic acid separated by distillation. The product so obtained is a solution of acetic acid in water, contain- MONOBASIC ACIDS. 193 ing 36 per cent, of true acetic acid, and being of sp. gr. 1.047, U. S. (the acid of the Br. Ph. is weaker—33 per cent. and sp. gr. 1.044). Pure acetic acid, known as glacial acetic acid, acidum aceticum glaciale (U. S.), is obtained by decomposition of a pure dry acetate by heat. Properties.—Acetic acid is a colorless liquid. Below 17° (62°.6 F.), when pure, it is a crystalline solid. It boils at 119° (246°.2 F.) ; sp. gr. 1.0801 at 0° (32° F.) ; its odor is penetrating and acid ; in contact with the skin it destroys the epidermis and causes vesication ; it mixes with H,0 in all proportions, the mixtures being less in volume than the sum of the volumes of the constituents. The sp. gr. of the mixtures gradually in- crease up to that containing 23 per cent, of H,0, after which they again diminish, and all the mixtures containing more than 43 per cent, of acid are of higher sp. gr. than the acid itself. Vapor of acetic acid burns with a pale, blue flame ; and is decomposed at a red heat. It only decomposes calcic carbonate in the presence of H.,0, Hot H3S04 decomposes and blackens it, SO,4 and CO„ being given oft'. Under ordinary circumstances Cl acts upon it slowly, more actively under the influence of sunlight, to produce monochloracetic acid, CH„ClCO,OH ; dichloracetic acid, CHC1.,C0,0H ; and trichloracetic acid, The last named is an odorless acid, strongly vesicant, crystalline solid ; fuses at 46° (114°.8 F.) and boils at 195°-200° (383°-392° F.). Analytical Characters.—(1.) Warmed with S04H, it blackens. (2.) With silver nitrate a white crystalline ppt., pai’tly dissolved by heat; no reduction of Ag on boiling. (3.) Heated with H4S04 and C..H.O, acetic ether, recognizable by its odor, is given off. (4.) When an acetate is calcined with a small quantity of As203 the foul odor cacodyl oxide is developed. (5.) Neutral solution of ferric chloride produces in neutral solutions of acetates a deep red color, which turns yellow on addition of free acid. Vinegar is an acid liquid owing its acidity to acetic acid, and hold- ing certain fixed and volatile substances in solution. It is obtained from some liquid containing 10 per cent, or less of alcohol, which is converted into acetic acid by the transferring of atmospheric oxygen to the alcohol during the process of nuti-ition of a peculiar vegetable ferment, known as mycoderma aceti, or, popularly, as mother of vinegar. Vinegar is now mamxfactured principally by one of two processes—the German method and that of Pasteur. In the foi*mer, the alcoholic fluid, which must also contain albuminous matter, is allowed to trickle slowly through bai*rels containing beech-wood shavings, supported by a perforated false bottom. By a suitable aiTangement of holes and tubes, an ascending cuiTent of air is made to pass through the barrel. The acetic ferment clings to the shavings, and under its influence acetification takes place rapidly, owing to the large surface exposed to the air. In Pasteur’s pi’ocess, the ferment is sown upon the surface of the alcoholic liquid, contained in large, shallow, covered vats, from which the vinegar is drawn oft’ after acetification has been completed ; the mother is collected, washed, and used in a subsequent operation. The liquids from which vinegar is made are wine, cider, and beer, to which dilute alcohol is frequently added ; the most esteemed being that obtained from white wine. Wine vinegar has a pleasant, acid taste and odor ; it consists of watei’, acetic acid (about 5 per cent.), potassium bitar- trate, alcohol, acetic ether, glucose, malic acid, minei’al salts present in wine, a fermentescible, niti’ogenized substance, coloring matter, etc. Sp. 194 MANUAL OF CHEMISTRY. gr. 1.020 to 1.025. "When evaporated, it yields from 1.7 to 2.4 per cent, of solid residue. Vinegars made from alcoholic liquids other than wine contain no po- tassium bitartrate, contain less acetic acid, and have not the aromatic odor of wine vinegar. Cider vinegar is of sp. gr. 2.0 ; is yellowish, has an odor of apples, and yields 1.5 per cent, of extract on evaporation. Beer vinegar is of sp. gr. 3.2 ; has a bitterish flavor, and an odor of sour beer ; it leaves 0 per cent, of extract on evaporation. The principal adulterations of vinegar are : sulphuric acid, which pro- duces a black or brown color when a few drops of the vinegar and some fragments of cane-sugar are evaporated over the water-batli to dryness. Water, an excess of which is indicated by a low power of saturation of the vinegar, in the absence of mineral acids. Two parts of good wine vinegar neutralize 10 parts of sodium carbonate ; the same quantity of cider vine- gar, 3.5 parts ; and of beer vinegar, 2.5 parts of carbonate. Pyroligneous acid may be detected by the creosote-like odor and taste. Pepper, capsi- cum, and other acrid substances, are often added to communicate fictitious strength. In vinegar so adulterated an acrid odor is perceptible after neutralization of the acid with sodium carbonate. Copper, zinc, lead, and tin frequently occur in vinegar which has been in contact with those ele- ments, either during the process of manufacture or subsequently. Distilled vinegar is prepared by distilling vinegar in glass vessels ; it contains none of the fixed ingredients of vinegar, but its volatile constitu- ents (acetic acid, water, alcohol, acetic ether, odorous principles, etc.), and a small quantity of aldehyde. When dry acetate of copper is distilled, a blue, strongly acid liquid passes over ; this, upon rectification, yields a colorless, mobile liquid, which boils at 56° (132°.8 F.), has a peculiar odor, and is a mixture of acetic acid, water, and acetone, known as radical vinegar. Toxicology.—When taken internally, acetic acid and vinegar (the latter in doses of 4-5 fl. 3 ) act as irritants and corrosives, causing in some in- stances perforation of the stomach, and death in 6-15 hours. Milk of magnesia should be given as an antidote, with the view to neutralizing the acid. Propionic acid—C H.CO,OH—74—is formed in many decomposi- tions of organic substances : By the action of caustic potassa upon sugar, starch, gum, and ethyl cyanide ; during fermentation, vinous or acetic ; in the distillation of wood ; during the putrefaction of peas, beans, etc. ; by the oxidation of normal propylic alcohol, etc. It is best prepared by heating ethyl cyanide with potash until the odor of the ether has disap- peared ; the acid is then liberated from its potassium compound by H ,S04 and purified. It is a colorless liquid, sp. gr. 0.996, does not solidify at — 21c (—5°.8 F.), boils at 140° (284° F.), mixes with water and alcohol in all proportions, resembles acetic acid in odor and taste. Its salts are soluble and crys- tallizable. Butyric acid—C3H7CO,OH —88—has been found in the milk, per- spiration, muscular fluid, the juices of the spleen and of other glands, the urine, contents of the stomach and large intestine, faeces, and guano ; in certain fruits, in yeast, in the products of decomposition of many vege- table substances ; and in natural waters ; in fresh butter in small quantity, more abundantly in that which is rancid. It is formed by the action of H2S04 and manganese dioxide, aided by heat, upon cheese, starch, gelatin, etc. ; during the combustion of tobacco MONOBASIC ACIDS. 195 (as ammonium butyrate ; by the action of HX03 upon oleic acitl; during the putrefaction of fibrin and other albuminoids ; during a peculiar fer- mentation of glucose and starchy material in the presence of casein or gluten. This fermentation, known as the butyric, takes place in two stages ; at first the glucose is converted into lactic acid: C6H1208 = 2(C3H603) ; and this in turn is decomposed into butyric acid, carbon di- oxide, and hydrogen : 2C3H603 = C4HpO„ + 2CO., -f 2H„. Butyric acid is obtained from the animal charcoal which has been used in the purification of glycerin, in which it exists as calcium butyrate. It is also formed by subjecting to fermentation a mixture composed of glu- cose, water, chalk, and cheese or gluten. The calcium butyrate is de- composed by H ,S04, and the butyric acid separated by distillation. Butyric acid is a colorless, mobile liquid, having a disagreeable, per- sistent odor of rancid butter, and a sharp, acid taste ; soluble in water, alcohol, ether, and methyl alcohol; boils at 164“ (627 .2 F.), distilling unchanged ; solidities in a mixture of solid carbon dioxide and ether ; sp. gr. 0.974 at 15° (59° F.) ; a good solvent of fats. It is not acted upon by H ,S04 in the cold, and only slightly under the influence of heat. Nitric acid dissolves it unaltered in the cold, but on the application of heat, oxidizes it to succinic acid. Dry Cl under the influence of sunlight, and Br under the influence of heat and pressure, form pro- ducts of substitution with butyric acid. It readily forms ethers and salts. Butyric acid is formed in the intestine, by the process of fermentation mentioned above, at the expense of those portions of the carbohydrate elements of food which escape absorption, and is discharged with the faeces as ammonium butyrate. Isobutyric acid, anisomere of butyric acid, which boils at 152° (305C.G F.), has also been found in human faeces. It corresponds to isobutyl alcohol. Valerianic acids—C H CO, OH—102.—Corresponding to the four primary amylic alcohols, there are four amylic or valerianic acids : I. CH3—CH — CH — CH — C O, OH. II. CH3//CH—CHa—CO,OH. ch,-c£i>ch-co’oh- CH3\ ch3—c—CO,oh. ch3/ m. IY. I. Normal valerianic acid—Butylformic acid—Propylacetic acid— is obtained by the oxidation of normal amylic alcohol. It is an oily liquid, boils at 185° (365° F.), and has an odor resembling that of butyric acid. II. III. Ordinary valerianic acid—Delphinic acid—Phocenic acid— Isovaleric acid—Isopropyl acetic add—Isobutylformic acid—Acid urn valeri- cinicum (Br.).—This acid exists in the oil of the porpoise, and in valerian root and in angelica root. It is formed during putrid fermentation or oxidation of albuminoid substances. It occurs in the urine and faeces in typhus, variola, and acute atrophy of the liver. It is also formed in a variety of chemical reactions and notably by the oxidation of amylic alcohol. It is prepared either by distilling water from valerian root, or, more economically, by mixing rectified amylic alcohol with H.,S04, adding when cold, a solution of potassium dichromate, and distilling after the reaction has become moderated : the distillate is neutralized with sodium carbon- ate ; and the acid is obtained from the sodium valerianate so produced, by decomposition by H,S04 and rectification. 196 MANUAL OF CHEMISTRY. The properties and nature of the acid differ according to those of the amyl alcohol from which it is obtained. The active alcohol yields the acid, CH \ (-qj3'/CH—CH ,—CO, OH, which is itself optically active ; which forms an uncrystallizable and exceedingly soluble barium salt, and whose boiling- point is 173°.5 (344°.3 F.). The inactive alcohol yields by oxidation the . CH \ acid, qjj qjj3^/CH—CO, OH, which is optically inactive ; whose barium salt is readily crystallizable and soluble in water to the extent of 48 parts in 100 ; and whose boiling-point is 174°.5 (346° F.). The acid obtained from valerian root is identical with the acid obtained by the oxidation of optically inactive amylic alcohol. The artificial product, being obtained from the commercial mixture of active and inactive alcohols, is a mixture in different proportions of the two acids mentioned above. The ordinary valerianic acid is an oily, colorless liquid, having a pene- trating odor, and a sharp, acrid taste. It solidifies at —16° (3°.2 F.); boils at 173°-175° (343°.4-347° F.) ; sp. gr. 0.9343-0.9465 at 20° (68° F.) ; burns with a white, smoky flame. It dissolves in 30 parts of water, and in alcohol and ether in all proportions. It dissolves phosphorus, camphor, and certain resins. IY. Trimetliyl acetic acid—Pivalic acid—is a crystalline solid, which fuses at 35.5° (963 F.) and boils at 163°.7 (326°.7 F.) ; sparingly soluble in H.,0 ; obtained by the action of cyanide of mercury upon tertiary butyl iodide. Caproic acids—Hexylic acids—CrHnCO,OH—116.—There probably exist quite a number of isomeres having the composition indicated above, some of which have been prepared from butter, cocoa-oil, and cheese, and by decomposition of amyl cyanide, or of hexyl alcohol. The acid obtained from butter, in which it exists as a glyceric ethei', is a colorless, oily liquid, boils at 205° (401° F.); sp. gr. 0.931 at 15° (59° F.); has an odor of perspiration and a sharp, acid taste ; is very sparingly soluble in water, but soluble in alcohol. CEnanthylic acid — Heptylic acid — CrHi:,CO,OH—130—exists in spirits distilled from rice and maize, and is formed by the action of HNOa on fatty substances, especially castor oil. It is a colorless oil; sp. gr. 0.9167 ; boils at 212° (413°.6 F.). Caprylic acid — Octylic acid — C.IIirCO,OH —144 — accompanies caproic acid in butter, cocoa-oil, etc. It is a solid ; fuses at 15° (59J F.); boils at 236° (457° F.); almost insoluble in H20. Pelargonic acid—Nonylic acid—C8H17CO,QH—158.—A colorless oil, solid below 10° (50° F.); boils at 260° (500° F.); exists in oil of geranium, and is formed by the action of HNOa on oil of rue. Capric acid — Becylic acid—CgH^CChOH—172—exists in butter, cocoa-oil, etc., associated with caproic and caprylic acids in their glyceric ethers, and in the residues of distillation of Scotch whiskey, as amyl caprate. It is a white, crystalline solid ; melts at 27°.5 (81°. 5 F.); boils at 273° (523°.4 F.). Laurie acid — Laurostearic acid—CnH.,sCO,OH—200—is a solid, fusible at 43°.5 (110°.3 F.) obtained from laui-el berries, cocoa-butter, and other vegetable fats. Myristic acid—0, 0^00,011—228.—A crystalline solid, fusible at 54° (129°.2 F.); existing in many vegetable oils, cow’s butter, and spermaceti. Palmitic acid — Ethalic acid—C]rH31CO,OH—256—exists in palm-oil, in combination when the oil is fresh, and free when the oil is old ; it also COMPOUND ETHERS. 197 enters into the composition of nearly all animal ancl vegetable fats. It is obtained from the fats, palm-oil, etc., by saponification with caustic potassa and subsequent decomposition of the soap by a strong acid. It is also formed by the action of caustic potash in fusion upon cetyl alcohol (ethal), and by the action of the same reagent upon oleic acid. Palmitic acid is a white, crystalline solid ; odorless ; tasteless ; lighter than HO, in which it is insoluble ; quite soluble in alcohol and in ether; fuses at 62° (143°.6 F.); distils unchanged with vapor of water. Margaric acid—C17H33CO,OH—270—formerly supposed to exist as a glyceride in all fats, solid and liquid. What had been taken for margaric acid wTas a mixture of 90 per cent, of palmitic and 10 per cent, of stearic acid. It is obtained by the action of potassium hydrate upon cetyl cyanide, as a white, crystalline body ; fusible at 59°. 9 (140° F.). Stearic acid—C17H36CO,OH—284—exists as a glyceride in all solid fats, and in many oils, and also free to a limited extent. To obtain it pure, the fat is saponified with an alkali, and the soap decomposed by HC1; the mixture of fatty acids is dissolved in a large quantity of alcohol, and the boiling solution partly precipitated by the addition of a concentrated solution of barium acetate. The precipitate is collected, washed, and decomposed by HC1; the stearic acid which sepa- rates is washed and recrystallized from alcohol. The process is repeated until the product fuses at 70° (158° F.). Pure stearic acid is a colorless, odorless, tasteless solid ; fusible at 70° (158° F.); unctuous to the touch; insoluble in H.,0 ; very soluble in alcohol and in ether. The alkaline stearates are soluble in H O ; those of Ca, Ba, and Pb are insoluble. Stearic and palmitic acids exist free in the intestine during the diges- tion of fats, a portion of which is decomposed by the action of the pan- creatic secretion into fatty acids and glycerin. The same decomposition also occurs in the presence of putrefying albuminoid substances. Arachic acid—C1)H3,)CO,OH—312—exists as a glyceride in peanut- oil (now largely used as a substitute for olive-oil), in oil of ben, and in small quantity in butter. It is a crystalline solid, which melts at 75° (167° F.). COMPOUND ETHERS. As the alcohols resemble the mineral bases, and the organic acids re- semble those of mineral origin, so the compound ethers are similar in con- stitution to the salts, being formed by the double decomposition of an alcohol with an acid, mineral or organic, as a salt is formed by double decomposi- tion of an acid and a mineral base, the radical playing the part of an atom of corresponding valence. K'}0 + (N°,) l o - Hl0 - (NO-)lo Hr + h ) u - Hr K' r Potassium hydrate. Nitric acid. Water. Potassium nitrate (CSH )') o , (NO.) )0 _ H|_0 (NOf))0 Hf U + H \ U “ H|u + (CSHS)' f U Ethyl hydrate (alcohol). Nitric acid. Water. Ethyl nitrate (nitric ether). 198 MANUAL OF CHEMISTRY. Methyl nitrate—} O—77.— ) A colorless liquid ; sp. gr. 1.182 at 22° (71 .6 F.) ; boils at 66° (150°.8 F.) ; gives off vapor which detonates at 1503 (302° F.). Prepared by the action of potassium nitrate and H.,S04 on methyl alcohol. Methyl ; O—61— \ )btained by heating- methyl alcohol with HN03 and Cu. Below—12° (10°.4 F.) it is a yellowish liquid ; above that temperature a gas. Ethyl nitrate—Nitric ether— | O—91.— A colorless liquid ; lias a sweet taste and bitter after-taste ; sp. gr. 1.112 at 17° (62°.6 F.) ; boils at 85° (185° F.) ; gives off explosive vapors. Prepared by distilling a mix- ture of HN03 and C,HrO in the presence of urea. Ethyl nitrite—Nitrous ether—qjj* •- O—75— is best prepared by directing the nitrous fumes, produced by the action of starch on HNO, under the influence of heat, into alcohol, contained in a retort connected with a well-cooled receiver. It is a yellowish liquid ; has an apple-like odor, and a sharp, sweetish taste; sp. gr. 0.947 ; boils at 18° (64°.4F.) ; gives off inflammable vapor ; very sparingly soluble in H.,0 ; readily soluble in alcohol and ether. Warm H,,0 decomposes it into CaH#0 ; HN03 and NO. Alkalies de- compose it into malate and nitrate of the alkaline element. It is ener- getically attacked by H,S04, H„S and the alkaline sulphides. It is liable to spontaneous decomposition, especially in the presence of H20, into NO and malic acid. Its vapor rapidly produces anaesthesia ; it is, however, used only in alco- holic solution: Spiritus cetheris nitrosi (U. S., Br.), which also contains aldehyde. Owing to the presence of the last-named substance, and to the presence of H.,0, the spirit is very liable to become acid, either from the formation of acetic acid by the oxidation of the aldehyde, or from the decomposition of the ether under the influence of H.,0, a change which renders it unfit for use in many of the prescriptions in which it is fre- quently used, especially in that with potassium iodide, from which it liber- ates iodine. The presence of free acid may be detected by effervescence when the spirit is shaken with liydrosodic carbonate. Its acidity may be corrected by shaking with potassium carbonate, and decanting, provided it does not contain H„0. Ethyl sulphates.—These are two in number : (C H,)HSOi—Ethyl- sulphuric, or sulphovinic acid ; (C.,HJ2S04—Ethyl-sulphate—Sulphuric ether. SOJ Ethyl-sulphuric Acid—(C„H.) >- 02—126—: ‘ H is formed as an interme- diate product in the manufacture of ethylic ether (q. v.). Pure ethyl-sulphuric acid is a colorless, syrupy, highly acid liquid ; sp. gr, 1.316 ; soluble in water and alcohol in all proportions, insoluble in ether. It decomposes slowly at ordinary temperatures, more rapidly when heated. When heated alone or with alcohol, it yields ether and H,S04. When heated with H.,0, it yields alcohol and H„S04. It forms crystal- line salts, known as sulphovinates, one of which, sodium suJphovinate, (C.,H.)NaS04, has been used in medicine. It is a white, deliquescent solid, COMPOUND ETHERS. 199 either crystalline with lAq., or granular and anhydrous ; soluble in H20. Its solution should give no precipitate with barium chloride. Ethyl Sulphate—,n l O,,—154— ;he true sulphuric ether, is ob- tained by passing vapor of SU3 into pure ethylic ether, thoroughly cooled. It is a colorless, oily liquid ; has a sharp, burning taste, and the odor of peppermint; sp. gr. 1.120; it cannot be distilled without decompo- sition ; in contact with H30 it is decomposed with formation of sulplio- vinic acid. By the action of an excess of H.,S04 upon alcohol; by the dry distil- lation of the sulphovinates ; and in the last stages of manufacture of ether, a yellowish, oily liquid, having a penetrating odor and a sharp, bitter taste, is formed ; this is sweet or heavy oil of wine, and its ethereal solution is Oleum, cethereum (U. S.). It seems to be a mixture of ethyl-sulphate with hydro- carbons of the series On contact with H,0 or an alkaline solution, it is decomposed, sulphovinic acid is formed, and there separates a color- less oil, of sp. gr. 0.917, boiling at 280° (536° F.), which is light oil of urine. This oil is polymeric with ethylene, and is probably cetene, Clt,H32; it is sometimes called etherine or etherol. Ethyl acetate—Acetic ether—JEther aceticus (U. S.)— ) C,HJU 88—is obtained by distilling a mixture of sodium acetate, alcohol and H2S04 ; or by passing carbon dioxide through an alcoholic solution of potassium acetate. It is a colorless liquid, has an agreeable, ethereal odor; boils at 743 (165°.2 F.) ; sp. gr. 0.89 at 15° (SO3 F.) ; soluble in 6 pts. water, and in all proportions in methyl and ethyl alcohols and in ether ; a good solvent of essences, resins, cantharidine, morphine, gun-cotton, and, in general, of substances soluble in ether ; burns with a yellowish white flame. Chlor- ine acts energetically upon it, producing products of substitution, varying according to the intensity of the light from C4HaCla02 to C4C1M02. obtained by distilling a mixture of HNO t and amylic alcohol in the presence of a small quantity of urea. It is a colorless, oily liquid ; sp. gr. 0.994 at 10° (50° F.) ; boils at 148° (298°.4 F.) with partial decomposition. Amyl nitrate— 1 O—133—< prepared by- directing the nitrous fumes, evolved by the action of NO.,H upon starch, into amyl alcohol contained in a retort heated over a water-bath ; purifying the distillate by washing with an alkaline solution ; and rectifying. It is a slightly yellowish liquid ; sp. gr. 0.877 ; boils at 95° (203° F.) ; its vapor explodes when heated to 260 (500° F.) ; insoluble in water; soluble in alcohol in all proportions; vapor orange-colored. Alcoholic solution of potash decomposes it slowly, with formation of potassium ni- trite and oxides of ethyl and amyl. When dropped upon fused potash, it ignites and yields potassium valerianate. Amyl nitrite is frequently impure ; its boiling-point should not vary more than two or three degrees from that given above. Amyl nitrite—Amyl nitris (U. S.)—! O—117— -is the chief constit- uent of spermaceti = cetaceum (U. S., Br.). This is the concrete portion, obtained by expression and crystallization from alcohol, of the oil con- tained in the cranial sinuses of the sperm-whale. It forms white, crystal- Cetyl palmitate—Cetine—j O—480— 200 MANUAL OF CHEMISTRY. line plates ; fusible at 49° (120°.2 F.) ; slightly unctuous to the touch ; tasteless, and almost odorless ; insoluble in water ; soluble in alcohol and ether ; burns with a bright flame. Besides cetine, it contains ethers not only of palmitic, but also of stearic, myristic, and laurostearic acids ; and of the alcohols : lethal, C12H2C0 ; methal, C14H30O ; ethal, CicH340 ; and stethal, C18H3B0. Beeswax con- sists mainly of two substances ; cerotic acid, whicli is soluble in boiling alcohol, and melissyl palmitate, insoluble in that liquid, united with minute quantities of substances which communicate to the wax its color and odor. Yellow wax melts at 62°-63° (143°.6-145°.4 F.) ; after bleach- ing, which is brought about by exposure to light, air, and moisture, it does not fuse below G6° (150°.8 F.). China wax, a white substance resembling spermaceti, is a vegetable product, consisting chiefly of ceryl cerotate, C21H5302(C27HJ. Melissyl palmitate — j- O—076.— ! ALDEHYDES Sekies C„H2)10 Formic aldehyde CH20. Acetic aldehyde C2H40. Propionic aldehyde C3H0O. Butyric aldehyde C4HsO. Isobutyric aldehyde C4H80. Valerianic aldehj'de C6H10O. Caproic aldehyde 06H12O. CEnanthylic aldehyde C7H140. Caprylic aldehyde CgH160. Palmitic aldehyde C16H 320. It will be remembered that the monobasic acids are obtained from the alcohols by oxidation of the radical: (OAUq H j u (03,0/ | 0 Ethyl alcohol. Acetic acid. These oxidized radicals are capable of forming compounds similar in con- stitution to those of the non-oxidized l'adicals. There are chlorides, bro- (C H O) ) mides, and iodides ; their hydrates are the acids, 2 3 jj | — acetic acid ; their oxides are known as anhydrides, | O = acetic anhy- dride ; and their hydrides are the aldehydes | = acetic aldehyde. The name aldehyde is a corruption of alcohol dehydrogenatum, from the method of their formation, by the removal of hydrogen from alcohol. The aldehydes all contain the group of atoms (COH)', and their con- stitution may be thus graphically indicated: COH I CH„ I CH COH I ch3 Acetic aldehyde. Propionic aldehyde. ALDEHYDES. 201 They are capable, by fixing H2, of regenerating the alcohol; and, by fixing O, of forming the corresponding acid : COH I CH, CH OH I CH, CO, OH I ch3 Acetic aldehyde. Ethylic alcohol. Acetic acid. is formed in all reactions in which alcohol is deprived of H without introduction of O. It is prepared by distilling from a capacious retort, connected with a well-cooled condenser, a mixture of H3S04, G pts.; H30, 4 pts. ; alcohol, 4 pts. ; and powdered manganese dioxide, 6 pts. The product is redistilled from cal- cium chloride below 50° (122° F.). The second distillate is mixed with two volumes of ether, cooled by a freezing mixture, and saturated with dry NH3; there separate crystals of ammonium acetylide, C H.,0, NHt, which are washed with ether, dried, and decomposed in a distilling apparatus, over the water-bath, with the proper quantity of dilute H3S04 ; the distillate is finally dried over calcium chloride and rectified below 35J (95° F.). Aldehyde is a colorless, mobile liquid ; has a strong, suffocating odor ; sp. gr. 0.790 at 18° (64°.4 F.) ; boils at 21° (69°.8 F.); soluble in all pro- portions in water, alcohol, and ether. If perfectly pure, it may be kept unchanged ; but if an excess of acid have been used in its preparation, it gradually decomposes. When heated to 100° (212° F.), it is decomposed into water and crotonic aldehyde. In the presence of nascent H, aldehyde takes up II„ and regenerates alcohol. Cl converts it into acetyl chloride, C„H30, Cl, and other products. Oxidizing agents quickly convert it into acetic acid. At the ordinary tem- perature H.,S04; 1IC1; and S02 convert it into a solid substance called ‘paraldehyde, C6H1503 (?), which fuses at 10.5° (50°.9 F.); boils at 124° (255°.2 F.), and is more soluble in cold than in warm water. When heated with potassium hydrate, aldehyde becomes brown, a brown resin separates, and the solution contains potassium formiate and acetate. If a watery solution of aldehyde be treated, first with NH3 and then with II„S, a solid, crystalline base, thialdine, CeH13NS2, separates. It also forms crystalline compounds with the alkaline bisulphites. It decomposes solutions of silver nitrate, separating the silver in the metallic form, and under condi- tions which cause it to adhere strongly to glass. Vapor of aldehyde, when inhaled in a concentrated form, produces as- phyxia, even in comparatively small quantity ; when diluted with air it is said to act as an anresthetic. When taken internally it causes sudden and deep intoxication, and it is to its presence that the first products of the distillation of spirits of inferior quality owe in a great measure their rapid, deleterious action. C H O ) Acetic aldehyde—Acetyl hydride— 2 3jj - —44— Trichloraldehyde — Tnchloracetyl hydride — Chloral — c,cim_ Hf 147.5—is one of the final products of the action of Cl upon alcohol, and is obtained by passing dry Cl through absolute alcohol to saturation ; apply - ing heat toward the end of the reaction, which requires several hours for its completion. The liquid separates into two layers ; the lower is removed and shaken with an equal volume of concentrated H3S04 and again allowed to separate into two layers ; the upper is decanted ; again mixed with H,S04, from which it is distilled ; the distillate is treated with quicklime, 202 MANUAL OF CHEMISTKY. from which it is again distilled, that portion which passes over between 94° and 99° (201°.2-210°.2 F.) being collected. It sometimes happens that chloral in contact with H2S04 is converted into a modification, insoluble in II„0, known as metachloral; when this occurs it is washed with H20, dried and heated to 180° (356° F.), when it is converted into the soluble variety, which distils over. Chloral is a colorless liquid, unctuous to the touch ; has a penetrating odor and an acrid, caustic taste ; sp. gr. 1.502 at 18° (64°.4 F.) ; boils at 94.4° (201°.9 F.) ; very soluble in water, alcohol, and ether ; dissolves Cl, Br, I, S and P. Its vapor is highly irritating. It distils without alteration. Although chloral has not been obtained by the direct substitution of Cl for H in aldehyde, its reactions show it to be an aldehyde; it forms crystalline compounds with the bisulphites ; it reduces solutions of silver nitrate in the presence of NH3; NH3 and H2S form with it a compound similar to thialdine ; with nascent II it regenerates aldehyde ; oxidizing agents convert it into trichloracetic acid. Alkaline solutions decompose it with formation of chloroform and a formiate. With a small quantity of II20 chloral forms a solid, crystalline hydrate, heat being at the same time liberated. This hydrate has the composition C„HC130,H20, and its constitution, as well as that of chloral itself, is indi- cated by the formulae: ch3 I CIIO CC13 I CHO CC13 CH(OH)2 Aldehyde. Tnchloraldehyde (chloral). Chloral hydrate. Chloral hydrate—Chloral (U. S.)—is a white, crystalline solid ; fuses at 57° (134°.6 F.) ; boils at 98° (208°.4 F.), at which temperature it suffers partial decomposition into chloral and II20 ; volatilizes slowly at ordinary temperatures; is very soluble in H20 ; neutral in reaction ; has an ethereal odor, and a sharp, pungent taste. Concentrated H2S04 decomposes it with formation of chloral and chloralide. HN03 converts it into trichlor- acetic acid. When pure it gives no precipitate with silver nitrate solution, and is not browned by contact with concentrated H2S04. Chloral also combines with alcohol, with elevation of temperature, to form a solid, crystalline body—chloral alcoholate: CC13— jj Action of Chloral Hydrate upon the Economy.—Although it was the ready decomposition of chloral into a formiate and chloroform which first suggested its use as a hypnotic to Liebreich, and although this decompo- sition was at one time believed to occur in the body under the influence of the alkaline reaction of the blood, more recent investigations have shown that the formation of chloroform from chloral in the blood is, to say the least, highly improbable, and that chloral has, in common with many other chlorinated derivatives of this series, the property of acting directly upon the nerve-centres. Neither the urine nor the expired air contain chloroform when chloral is taken internally ; when taken in large doses, chloral appears in the urine. The fact that the action of chloral is prolonged for a longer period than that of the other chlorinated derivatives of the fatty series is probably due, in a great measure, to its less volatility and less rapid elimination. When taken in overdose, chloral acts as a poison, and its use as such KETONES OR ACETONES 203 is rapidly increasing as acquaintance with its powers becomes more widely disseminated. No chemical antidote is known. The treatment should be directed to the removal of any chloral remaining in the stomach by the stomach-pump, and to the maintenance or restoration of respiration. In fatal cases of poisoning by chloral that substance may be detected in the blood, urine, and contents of the stomach by the following method : the liquid is rendered strongly alkaline with potassium hydrate; placed in a flask, which is warmed to 50 -60” (122G-110 F.), and through which a slow current of air, heated to the same temperature, is made to pass ; the air, after bubbling through the liquid, is tested for chloroform by the methods described on p. 113. If affirmative results are obtained in this testing, it remains to determine whether the chloroform detected existed in the fluid tested in its own form, or resulted from the decomposition of chloral; to this end a fresh portion of the suspected liquid is rendered acid and tested as before. A negative result is obtained in the second testing when chloral is present. Bromal—^BrP >. _281.—. H \ A colorless, oily, pungent liquid ; sp. gr. 3.34; boils at 1723 (341°.6 F.); neutral; soluble in 1I20, alcohol, and ether. It combines with H„0 to form brornal hydrate, CBrs,CH(OH)a; large transparent crystals ; soluble in H20 ; decomposed by alkalies into bromoform and a formiate. Produces anaesthesia without sleep; very poisonous. KETONES OR ACETONES. Sekies C„Ha„0. Although the aldehydes are not acid in reaction, and are not usually regarded as acids, there exist substances known as ketones or acetones, which may be regarded as formed by the substitution of an alcoholic radi- cal for the H of the group COH. These substances all contain the group of atoms (CO)", and their constitution may be represented graphically thus : ch3 I CO I CH3 ch3 I CO I ch2 I CH3 3 Methyl-ethyl ketone. Dimethyl ketone (acetone). the first being a symmetrical ketone and the latter a non-symmetrical. The ketones are isomeric with the aldehydes, from which they are distinguished : 1st, by the action of H, which produces a primary alcohol with an alde- hyde, and a secondary alcohol with a ketone : COH CH2OH I I ch2 + h2 = ch2 ! ' I CH, CH, Propionic aldehyde. Propyl alcohol. 204 MANUAL OF CHEMISTRY. OH, CHS I I CO + H3 = CH,OH I ‘ I ch3 ch. Acetone. Isopropyl alcohol. 2d, by the action of O, which unites directly with an aldehyde to produce the corresponding acid, while it causes the disruption of the molecule of the .ketone, with formation of two acids : COH CO, OH ! I CH, + 0 = CH, ch3 CHS Propionic aldehyde. Propionic acid. ch3 I CO,OH CO,OH CO 4- 03 = | +| I H CHS ch, Acetone. Form'c acid. Acetic acid. Dimethyl ketone — Acetone — Acetylmethylide—Pyroacetic ether or spirit — is formed as one of the products of the dry dis- tillation of the acetates ; by the decomposition of the vapor of acetic acid at a red heat; by the dry distillation of sugar, tartaric acid, etc.; and in a number of other reactions. It is obtained by distilling dry calcium acetate in an earthenware retort at a dull red heat; the distillate, col- lected in a well-cooled receiver, is freed from H„0 by digestion with fused calcium chloride, and rectified ; those portions being collected which pass over at 60° (140° F.). It is also formed in large quantity in the preparation of aniline. cotN0 —m— -is an isomere of choline, exist- ing along with muscarine (see below) in Agaricns muscarius. By oxidation with HNOa it yields muscarine. —is a substituted tetra- methylammonium hydrate closely related to choline and amanitine, from the former of which it may be obtained by oxidation. It occurs in nature in Agaricus muscarius, and is produced during pu- trefactive decomposition of albuminoid substances. Its formation under such circumstances is of great importance, not only by reason of its ac- tively poisonous qualities, but for the reason that, with the exception of the amines above mentioned, it is the only alkaloid formed during putre- faction which is known to be a product of the vegetable world as well. The free alkaloid occurs in very deliquescent, irregular crystals, or, if not perfectly dry, a colorless, odorless, and tasteless, but strongly alkaline syrup ; readily soluble in all proportions in water and in alcohol; very sparingly soluble in chloroform ; insoluble in ether. It is a more powerful base than ammonium hydrate, forming an alkaline carbonate and neutral salts with other acids. When decomposed it yields trimethylamine. Its platinochloride crystallizes in octaliedra. Its chloride forms colorless, brilliant, deliquescent needles. When administered to animals, muscarine causes increased secretion of saliva and tears; vomiting ; evacuation of feces, at first solid, later liquid ; contraction of the pupils, almost to the extent of closure ; diminution of the rapidity of the pulse ; interference with respiration and locomotion ; grad- ual sinking of the heart’s action and respiration ; and death. Atropine Muscarine [ N>OH = C.H,.N0>- 208 MANUAL OF CHEMISTRY. prevents the action of muscarine, and diminishes its intensity when already established. Neurine—Trim ethylvinylammonium hydrate, (cl’i j-NOH = C H . NO, is a substance nearly related to choline, and long confounded with it, supposed by Liebreicli to exist in the brain. The same body is one of the alkaloids produced by the putrefaction of muscular tissues, and is en- dowed with poisonous qualities, resembling, but less intense than, those of muscarine. Another cadaveric alkaloid, related to neurine and produced under similar conditions, is a diamine ; neuridine, CDH14N2. MONAMIDES. These bodies differ from the amines in containing oxygenated, or acid radicals, in place of alcoholic radicals. Like the amines, they are divisible into primary, secondary, and tertiary. They are the nitrides of the acid radicals, as the amines are the nitrides of the alcoholic radicals. The monamides may also be regarded as the acids in which the OH of the group COOH has been replaced by (NH2) : CH3 I COOH ch3 I conh2 Acetic acid. Acetamide. The primary monamides, containing radicals of the acids of the acetic series, are formed : (1.) By the action of heat upon an ammoniacal salt: (C2H30)')0_H)0 (CsH30)')n NH , \ u ~ H \ U + H , f (2.) By the action of a compound ether upon ammonia : Ammonium acetate. Water. Acetamide. Ethyl acetate. Ammonia. Acetamide. Alcohol. (3.) By the action of the chloride of an acid radical upon dry NH3: ,c'h'°<5 hs d J») - ” a s+"’■"■'s:!» Acetyl chloride. Ammonia. Ammonium chloride. Acetamide. The secondary monamides of the same class are obtained : (1.) By the action of the chlorides of acid radicals upon the primary amides : (O.H.OT } N +(C'H'°ci \ = **%}* + %} Acetamide. Acetyl chloride. Diacctamide. Hydrochloric acid. AMIDO-ACIDS OF THE FATTY SERIES 209 (2.) By the action of HC1 upon the primary monamides at high tem- peratures : Acetamide. Hydrochloric acid. Diacetamide. Ammonium chloride. The tertiary monamides of this series of radicals have been but im- perfectly studied ; some of them have been obtained by the action of the chlorides of acid radicals upon metallic derivatives of the secondary amides. The primary monamides containing radicals of the fatty acids are solid, crystallizable, neutral in reaction, volatile without decomposition, mostly soluble in alcohol and ether, and mostly capable of uniting with acids to form compounds similar in constitution to the ammoniacal salts. They are capable of uniting with H,0 to form the ammonical salt of the cor- responding acid, and with the alkaline hydrates to form the metallic salt of the corresponding acid, and ammonia. The secondary monamides, containing two radicals of the fatty series, are acid in reaction, and their remaining atom of extra-radical H may be replaced by an electro-positive atom. is obtained by heating, under press- ure, a mixture of ethyl acetate and aqua ammonise, and purifying by distillation. It is a solid, crystalline substance, very soluble in H.,0, alcohol, and ether ; fuses at 78° (172°. I F.) ; boils at 221° (429°.8 F.); has a sweetish, cooling taste, and an odor of mice. Boiling potassium hy- drate solution decomposes it into potassium acetate and ammonia. Phos- phoric anhydride deprives it of HaO, and forms with it acetonitrile or methyl cyanide. Acetamide—jj j N—59— AMIDO-ACIDS OF THE FATTY SERIES. These compounds, also known as glycocols, are of mixed function, acid and basic, obtained by the substitution of the univalent group (NH,)' for an atom of radical H of an acid : ch3 I COOH CH,(NH,) COOH Acetic acid. Amido-acetic acid (glycocol). Some of them, and many of their derivatives, exist in animal bodies. Corresponding to them are many isomeres belonging to other series. Amido-acetic acid—Glycocol—Sugar of gelatin—Glycolamic acid— Glycine- was first obtained by the action of H2S04 upon gelatin. It is best prepared by acting upon glue with caustic potassa, NH3 being liberated ; H2S04 is then added, and the crystals of potassium sulphate separated; the liquid is evaporated, the residue dissolved in alcohol, from which solution the glycocol is allowed to crystallize. ch„,nh2 - I ‘ -75- COOH 210 MANUAL OF CHEMISTRY. It may also be obtained synthetically by a method which indicates its constitution—by the action of ammonia upon chloracetic acid : CH„C1 H\ CH„NH2 h I ' + H-N = | ■ + n COOH H / COOH Chloracetic acid. Ammonia. Amido-acetic acid. Hydrochloric acid. It may be obtained from ox-bile, in which it exists as the salt of a con- jugate acid ; from uric acid by the action of hydriodic acid; and by the union of formic aldehyde, hydrocyanic acid, and water. It is isomeric with glycolamide. It has been found to exist free in animal nature only in the muscle of the scallop, and, when taken internally, its constituents ai*e eliminated as urea. In combination it exists in the gelatinoids, and with cholic acid as sodium giycocliolate (q. v.) in the bile. It is one of the products of decomposition of glycocliolic acid, hyoglycocholic acid, and hippuric acid by dilute acids and by alkalies, and of the decomposition of tissues containing gelatinoids. It appears as large, colorless, transparent crystals ; has a sweet taste ; melts at 170° (338° F.); decomposes at higher temperatures; sparingly soluble in cold H20 ; much more soluble in warm H„U ; insoluble in abso- lute alcohol and in ether; acid in reaction. It combines with acids to form crystalline compounds, which are de- composed at the temperature of boiling water ; hot H2S04 carbonizes it; HN03 converts it into glycolic acid (q. v.); with HC1 it forms a chloride ; heated under pressure with benzoic acid it forms hippuric acid. Its acid function is more marked; it expels carbonic and acetic acids from calcium carbonate and plumbic acetate. The presence of a small quantity of glycocol prevents the precipitation of cupric hydrate from cupric sulphate solution by potassium hydrate ; the solution becomes dark blue, does not yield cuprous hydrate on boiling, and precipitates crystalline needles of copper glycolamate on the addition of alcohol to the cold solution. With ferric chloride it gives an intense red solution, whose color is discharged by acids, and reappears on neutralization. With phenol and sodium hypo- chlorite it gives a blue color, as does ammonia. By oxidation with potas- sium permanganate in alkaline solution it yields carbon dioxide, oxalic, carbonic, and oxamic acids, and water. It also forms crystalline com- pounds with many salts and ethers. Methyl amido-acetate is isomeric with sarcosine: CHNH I COOH CH2NHa cooch3 CH,NH(CEL3) I COOH Methyl amido-acetate. Glycocol (amido-acetic acid). Sarcosine ( methyl-glycocol). Methyl-glycocol—Sarcosine- —89—isomeric with alanine and with lactamide (q. v.), does not exist as such in animal nature, but has been obtained from creatine (q. v.) by the action of barium hydrate : CH2[NH(CH3)] COOH C,H,N302 + H,0 = C3H4N02 + CON.H4 ; Creatine. W ater. Sarcosiue. Urea. urea being formed at tlie same time, and decomposed by the further action of the barium hydrate into NH3 and barium carbonate. AMIDO-ACIDS OF THE FATTY SERIES 211 Its constitution is indicated by its synthetic formation from chloracetic acid and methylamine : CHaCl CH3\ CH [NH(CH,)J „ | + H-N =1 + £ COOH H / COOH Chloracetic acid. Methylamine. Sarcosine. Hydrochloric acid. It crystallizes in colorless, transparent prisms ; very soluble in water; sparingly soluble in alcohol and ether. Its aqueous solution is not acid, and has a sweetish taste ; it unites with acids to form crystalline salts, but does not form metallic salts. It is capable of combining with cyanamide to form creatine. Betaine — Trimethyl glycocol—Oxyneurine — Oxy choline— •was first obtained from the juice of the sugar-beet; afterward it was obtained by oxidation of choline ; and is also produced synthetically, either by acting upon trimethylamine with mono- chloracetic acid, as glycocol is obtained by the action of the same acid upon ordinary ammonia ; or by acting upon glycocol itself with methyl iodide. Betaine crystallizes in large, brilliant crystals, containing one molecule of water of crystallization. At the ordinary temperature they are deli- quescent, but at 100° (212° F.) effloresce, and lose their Aq. It is very soluble in water and in alcohol. It is decomposed by heat, Avitli evolution of trimethylamine. It forms crystalline salts. Its chloraurate is crystal- line and very sparingly soluble in cold water. The method of its synthesis and the composition of its chloride indi- cate it to be related to tetramethylammonium hydrate, but when its chlo- ride is decomposed by silver oxide, it is not with substitution of OH for Cl, but with separation of Cl + HaO. Betaine is the type of a number of similar compounds derivable from the amido acids by substitution of various hydrocarbon radicals. CH—CO I I = WO -117- (CHa);iN - O CH„—CH„ (NHJ I COOH Amidopropionic Acid—Alanine— -89.—Isomeric with sarcosine and with lactamide ; does not exist, as far as is known at present, in nature. It is obtained by the action of alcoholic ammonia upon bromopropionic acid : CH.Br CH„(NH2) ! /H\ \ i CH, + 2/ H—N) = CH, + BrNH4 I \H/ / I COOH COOH Bromopropi onic acid. Ammonia. Amidopropi- onic acid. Ammonium bromitle. It may also be prepared by starting from lactic acid, from which it differs by containing NH, in place of OH. It crystallizes in large, oblique, rhombic prisms ; very soluble in HO ; sparingly soluble in alcohol; insoluble in ether. Its aqueous solution is neutral and sweet. Nitrous acid converts it into lactic acid, N, and H.,0. It dissolves in acids without neutralizing them, but yet, in certain cases, with the formation of crystalline compounds. Its Ba, Pb, Cu, and Ag salts are soluble and crystalline. 212 MANUAL OF CHEMISTRY. Amidobutyric Acid—Butalanine—C4H9N02—and Amidovaleri* anic acid—C5HnNO a—are only of theoretic interest at present. The latter has been found in the tissue of the pancreas and among the products of the action of pancreatic juice upon albumin. They are among the pro- ducts of the decomposition of albumin by caustic baryta. CH-C3H-CH.,(NHJ Amidocaproic Acid—Leucine— | =C6H13N02 COOH —131—exists widely distributed in animal nature ; it lias been obtained from the normal spleen, pancreas, salivary, lymphatic, thymus, and thyroid glands, lungs, and liver. Pathologically, its quantity in the liver is much increased in diseases of that organ, and in typhus and variola ; in the bile in typhus ; in the blood in leucocythaemia, and in yellow atrophy of the liver ; in the urine in yellow atrophy of the liver, in typhus, and in variola ; in choleraic discharges from the intestine ; in pus ; in the fluids of dropsy; and of atheromatous cysts. In these situations it is usually accompanied by tyrosine (q. v.). It is much more abundant in the tissues of the lower forms of animal life, and has also been found in vegetable tissues. It is formed by the decomposition of nitrogenized animal and vegetable substances, by heating with strong alkalies or dilute acids ; by the decom- position of elastic tissues it is formed with a small quantity of tyrosine ; by that of gelatinoid materials, leucine and glycine are obtained ; by that of albuminoids, leucine and a small, but variable, quantity of tyrosine are formed ; and that of epidermic tissues yields leucine and tyrosine. It is also one of the products of the putrefaction of animal and vegetable albu- minoids, and of the action of pancreatic juice upon fibrin. It has also been formed synthetically by the action of NH3 upon bromocaproic acid, in the same way that alanine is formed from bromopropionic acid (see above). It may be obtained by a variety of methods, the most advantageous of which consists in boiling 1 pt. horn-shavings with 4 pts. H ,S04 and 12 pts. H O, for 36 hours, renewing the H20 as it evaporates ; the acid liquid is saturated with milk of lime and boiled again for 24 hours; it is then filtered through linen, a slight excess of H2S04 is added, and the liquid again filtered and evaporated ; tyrosine first crystallizes out and is sepa- rated, after which leucine separates in crystals, which are purified by re- crystallization from a small quantity of H,0, the crystals first formed being rejected. The leucine so obtained is further purified by solution in hot H20 ; digestion with lead hydrate ; filtration ; treatment with H.S ; fil- tration ; treatment with animal charcoal; filtration and crystallization. Leucine crystallines from alcohol in soft, pearly plates, lighter than H20, and somewhat resembling cholesterin ; sometimes in round masses composed of closely grouped needles radiating from a centre. It is spar- ingly soluble in cold HO ; readily in warm H O ; almost insoluble in cold alcohol and ether ; soluble in boiling alcohol, which deposits it on cooling ; it is odorless and tasteless, and its solutions ai'e neutral. Its solubility in H,0 is increased by the presence of acetic acid or of potassium acetate. It sublimes at 170° (338° F ) without decomposition ; if suddenly heated above ISO3 (3563 F.), it is decomposed into amylamine and carbon dioxide. When heated to 140° (284° F.), with hydriodic acid underpressure, it is decomposed into caproic acid and ammonia. Nitrous acid converts it into leucic acid, C0H]2O3, H O and N. It unites with acids to form solu- ble, crystalline salts. It also dissolves readily in solutions of alkaline hy- drates, forming crystalline compounds with the metallic elements. The formation of leucine in the body is one of the steps of the trans- AMI DO-ACIDS Or T1IE FATTY SERIES. 213 formation of at least some part of the albuminoids into urea. That leucine is formed at the expense of the albuminoids by some fermentation-like process, there can be no doubt. As it is only discharged in the urine in certain exceptional pathological conditions, and as at the same time the elimination of urea is greatly diminished, it seems highly probable that under normal conditions the N of leucine finally makes its exit from the body as urea, notwithstanding the fact that chemists have hitherto been unable to obtain urea from leucine artificially. As to the nature of the changes by Avhich leucine is converted into urea in the body, we are as yet in the dark. When leucine and tyrosine appear in the urine, that fluid is poor in urea and usually contains biliary coloring matters ; the substitution of leucine for urea may be so extensive that the urine con- tains no urea, and contains leucine in such quantity that it crystallizes out spontaneously. Analytical Characters.—The presence of leucine and tyrosine in the urine may be detected as follows : the freshly collected urine is treated with basic lead acetate, filtered, the filtrate treated with H.,S, filtered from the precipitated lead sulphide, and the filtrate evaporated over the water- bath ; leucine and tyrosine crystallize ; they may be separated by extrac- tion of the residue with hot alcohol, which dissolves the leucine and leaves the tyrosine. The leucine left by evaporation of the alcoholic solu- tion may be recognized by its crystalline form and by the following characters : (1) a small portion is moistened on platinum foil with HN03, which is then cautiously evaporated ; a colorless residue remains, which, when warmed with caustic soda solution, turns yellow or brown, and by further concentration is converted into oily drops, which do not adhere to the platinum (Scherer’s test); (2) a portion of the residue is heated in a dry test-tube ; it melts into oily drops, and the odor of amylamine (odor of ammonia combined with that of fusel oil) is observed ; (3) if a boiling mixture of leucine and solution of neutral lead acetate be carefully neu- tralized with ammonia, brilliant crystals of a compound of leucine and lead oxide separate ; (4) leucine carefully heated in a glass tube, open at both ends, to 17CP (338° F.), sublimes without fusing, and condenses in fiocculent shreds, resembling those of sublimed zinc oxide. If heated be- yond 180° (356° F.), the decomposition mentioned in 2d occurs. Tyrosine—CgH^TO.,—145—is a substance which does not belong to this series, and is probably an amido-acid of the aromatic series ; neverthe- less, as its constitution is still undetermined, and as it is almost universally found to accompany leucine in animal tissues and in the products of their decomposition, it may be considered in this place. The methods of its formation and preparation are given under leucine. It crystallizes from its watery and ammoniacal solutions in silky needles, arranged in stellate bundles ; very sparingly soluble in cold H.,0 ; almost insoluble in alcohol ; more soluble in hot H,0. When heated, it turns brown and yields an oily matter having the odor of phenol ; when heated in small quantities to 270° (518° F.), it is decomposed into carbon dioxide and a Avliite solid, having the composition which sublimes. It combines with both acids and bases. It has been found in animal nature in the same situations as leucine. When taken into the stomach it is not altered in the economy, but is eliminated in the urine and frnces. Analytical Characters.—(1) its crystalline form ; (2) when heated it gives off an odor of phenol ; (3) when moistened with HXO„ and careful- ly evaporated, a deep yellow residue remains, which turns darker with 214 MANUAL OF CHEMISTRY. NaHO ; (4) with concentrated H2S04 and slightly warmed, it dissolves with a transient red color—the solution, filtered and neutralized with CaCOa, gives a violet color with Fe.2Cl„ solution ; (5) when boiled with acid nitrate of mercury solution, a pink color, and later, a red precipi- tate. Biliary Acids.—The bile of most animals contains the sodium salts of two amido-acids of complex constitution. These acids may be decomposed into a non-nitrogenized acid (cholic acid), and either an amido-acid (glyco- col), or an amido-sulphurous acid (taurine). The following biliary acids have been described: Glycocholic acid—C2f.H4.(N06—4G5—(sometimes designated as acide cholique, cholsdure, cholic acid, by French and German writers). It exists as its sodium salt in the bile of the herbivora, and in much smaller proportion in that of the carnivora ; it exists in small quantity in human blood and urine in icterus ; in human bile its quantity varies with the diet. It is best obtained from ox-bile ; this is evaporated to one-fourtli of its original volume, the residue is ground up with animal charcoal, and dried at 100° (212° F.); the dry mass, while still hot, is broken up and introduced into a flask, in which it is digested with absolute alcohol, with repeated agitation, for some days ; the colorless, filtered alcoholic solution is partially evaporated, but not to the extent of becoming syrupy, then mixed with an excess of anhydrous ether, which, if the reagents were free from H„0, causes the immediate separation of a crystalline precipitate of the mixed biliary salts. If the alcohol or ether used contain H20, the precipitate is at first resinous and only becomes crystalline after standing, or does not become crystalline if the proportion of H20 be too great. The crystalline deposit is collected upon a filter, washed with ether and dissolved in a small quantity of H20 ; to the aqueous solution a small quantity of ether is added, and then enough dilute H.,S04 to render the mixture permanently cloudy ; the glycocholic acid gradually crystallizes out, and may be further purified by solution in alcohol, and precipitation with a great excess of ether. Glycocholic acid forms brilliant, colorless, transparent needles, which are sparingly soluble in cold H20, readily soluble in warm H„0 and in alcohol, almost insoluble in ether. The watery solution is acid in reac- tion, and tastes at first sweet, afterward intensely bitter. Its alcoholic solu- tion exerts a right-handed polarization [a]D = + 29° ; when evaporated it leaves the acid in a resinous form. When heated with potash, baryta, or dilute H2S04 or II Cl, it is de- composed into cholic acid and glycocol: c26h43no6 + h2o = c,4h40o5 + c2h6no2. Glycocholic acid. Water. Cholic acid. Glycocol. Giycocholic acid dissolves unchanged in cold concentrated H.,S04, and is precipitated on dilution of the solution with H.,0 ; if the mixture be warmed the bile acid is decomposed, and there separate oil}' drops of cholonic acid, C26H41NOB, differing from glycocliolic acid by — H„0. When allowed to remain long in contact with concentrated HS04, glycocliolic acid is converted into a colorless, resinous mass, which slowly forms a saffron- yellow solution with the mineral acid, which turns flame-red when warmed, and which, on dilution, deposits a flocculent material which is colorless, greenish, or brownish, according to the temperature at which it AM IDO-ACIDS OF THE FATTY SERIES 215 is formed. Glycocliolic acid, altered by contact with concentrated H,S04, absorbs O when exposed to the air, and turns red, then blue, and finally brown after a few days. Sodium Glycocholate, C.,,H4.,NOfiNa, exists in the bile ; it crystallizes in stellate needles, very soluble in H.,0, less so in absolute alcohol, and insoluble in ether ; its acoholic solution exerts right-handed polarization [«]D = +25°.7. Lead Glycocholate, (C„6H49NO#), Pb (?), is formed as a white, floccu- lent precipitate, when solution of lead subacetate is added to a solution of a glycocholate or of glycocliolic acid ; with the neutral acetate the pre- cipitation does not occur in the presence of an excess of acetic acid. It is soluble in alcohol, and in an excess of lead acetate solution. The glycocholates of the alkaline earths are soluble in H.,0. Gly- cocliolic acid and the glycocholates react with Pettenkofer's test (see below). Glycocliolic acid forms compounds with the alkaloids, some of which are crystalline, others amorphous ; they are for the most part very spar- ingly soluble in H.,0, but readily soluble in solutions of the biliary salts and in bile. Tauroobolic acid—C26H45NOTS—515—(choleic acid of Strecker)— exists as its sodium salt in the bile of man and of the carnivora, and in much less abundance in that of the herbivora ; in the bile of the dog it seems to be unaccompanied by any other biliary acid. It may be obtained from dog’s bile by a modification of the method described under glyco- cholic acid ; the watery solution is not treated with H.,S04, as in the preparation of that acid, but with solution of basic lead acetate and am- monia. The precipitate so formed is extracted with boiling alcohol, the solution filtered hot and treated with H„S ; the clear liquid, filtered from the precipitated lead sulphide, is evaporated to a small bulk and treated with a large excess of ether ; the acid is precipitated in the resinous form, but, after standing for a varying period, assumes the crystalline form. When carefully prepared it forms silky, crystalline needles, which, when exposed to the air, deliquesce rapidly, and which, even under abso- lute ether, are gradually converted into a transparent, amorphous, resinous mass. It is soluble in HO and alcohol; insoluble in ether; its aqueous solution is very bitter ; in alcoholic solution it deviates the plane of polar- ization to the right, [a]D= + 24°.5; its solutions are acid in reaction. Taurocholic acid is very readily decomposed by heating with barium hydrate, with dilute acids, and even by evaporation of its solution, into cholic acid and taurine: Taurocholic acid. c,6h45no7s + Hao = c„4H10o. + csH7i;o,n Water. Cholic acid. Taurine. The same decomposition occurs in the presence of putrefying and in the intestine. Taurocholic acid has not been found to accompany glycocliolic in the urine of icteric patients. The taurocliolates are neutral in reaction ; those of the alkaline metals are soluble in alcohol and in water; and by long contact with ether they assume the crystalline form. They may be separated from the glycocho- lates in watery solution, either: (1) by dilute H.,S04 in the presence of a small quantity of ether, which precipitates glycocliolic acid alone ; or (2) by adding neutral lead acetate to the solution of the mixed salts (which must be neutral in reaction) lead glycocholate is precipitated and separated by M AN UAL OF CHEMISTRY. filtration; to the mother liquor basic lead acetate and ammonia are added, when lead taurocliolate is precipitated. The acids are obtained from the hot alcoholic solutions of the Pb salts by decomposition with H2S, filtra- tion, concentration, and precipitation by ether. Solutions of the taurocliolates, like those of the glycocholates, have the power of dissolving cliolesterin and of emulsifying the fats ; they also form with the salts of the alkaloids compounds which are insoluble in H.,0, but soluble in an excess of the biliary salt. The taurocliolate of morphine is crystallizable. They react with Pettenkofer’s test. Hyoglycocholic acid, C„.H.aKOr, and Hyotaurocholie acid, C„,H4rNOfS, (?) are conjugate acids of hyocholic acid, C2fH40O4, and glycocol and taurine, which exist in the bile of the pig. Chenotauroeholic acid, a conjugate acid of taurine and chenocholic acid, C27H4404, is obtained from the bile of the goose. Cholic acid—C H O—408—(cholalic acid of Strecker), is a product af decomposition of glyco- and taurocholic acids, obtained as indicated above. It also occurs, as the result of a similar decomposition, in the intestines and faeces of Doth lierbivora and carnivora. It forms large, clear, deliquescent crystals ; sparingly soluble in H20, readily soluble in alcohol and ether ; intensely bitter in taste, with a sweetish aftertaste ; in alcoholic solution it is dextrogyric [a]D = +35°. The alkaline cholates are crystallizable and readily soluble in H20, the others difficultly soluble. Cholic acid and the cholates respond to Pettenkofer's test. By boiling with acids or by continued heating to 200° (392° F.), cholic acid loses the elements of H„0, and is transformed into dyslysin, C,MH.,rO„ a neutral, resinous material, insoluble in H.,0 and alcohol, sparingly solu- ble in ether. The Pettenkofer Reaction.—All of the biliary acids, and the cholic acid and dyslysin obtained by their decomposition, have the property of forming a yellow solution with concentrated H2S04, the color of which rapidly increases *in intensity, and which exhibits a green fluorescence. Their watery solutions also, when treated with a small quantity of cane- sugar and with concentrated H2S04, so added that the mixture acquires a temperature of 70° (158° F.) but does not become heated much beyond that point, develop a beautiful clierry-red color, which gradually changes to dark reddish purple. Although this reaction is observed in the pres- ence of very small quantities of the biliary acids, it loses its value, unless applied as directed below, from the fact that many other substances give the same reaction, either with H.,S04 alone, or in the presence of cane- sugar. Among these substances are many which exist naturally in animal fluids, or which may be introduced with the food or as medicines ; such are cliolesterin, the albuminoids, lecithin, oleic acid, cerebrin, phenol, tur- pentine, tannic acid, salicylic acid, morphine, codeine, many oils and fats, cod-liver oil, etc. It has been suggested that a distinction could be made between the color produced by the Pettenkofer test with the biliary acids and those produced by the same test with other substances, by spectro- scopic observation ; the test with biliary acids in watery solution exhibit- ing a single dark and broad absorption-band (Fig. 34, No. 2) ; the same test in alcoholic solution shows two bands (No. 1) ; but while this spec- trum differs from those observed in the purple solutions obtained with many other substances, such as albumin (No. 3) ; it does not differ suffi- ciently from that obtained with the morphine salts (No. 4) to render it a safe method for controlling the test. The following method of applying Pettenkofer’s test to the urine and AMIDO-ACIDS OF THE FATTY SERIES. 217 other fluids removes, we believe, every source of error. The urine, etc., is first evaporated to dryness at the temperature of the water-bath, a small quantity of coarse animal charcoal having been added ; the residue is extracted with absolute alcohol, the alcoholic liquid filtered, partially evaporated, and treated with ten times its bulk of absolute ether ; after standing an hour or two, any precipitate which may have formed is col- lected upon a small filter, washed with ether, and dissolved in a small quantity of H,0 ; this aqueous solution is placed in a test-tube, a drop or two of a strong aqueous solution of cane sugar (sugar, 1 ; water, 4), and then pure concentrated H4S04 are added ; the addition of the acid being so regulated, and the test-tube dipped from time to time in cold water, that the temperature shall be from 60°-75° (140°-167° F.). In the pres- ence of biliary acids the mixture usually becomes turbid at first, and then turns clierry-red and finally purple, the intensity of the color varying with the amount of biliary acid present. Fig. 34. Physiological Chemistry of the Biliary Acids.—These substances do not normally pre-exist in the blood, and are consequently formed in the liver, and they are not reabsorbed from the intestine unchanged. Solu- tions of the biliary salts, injected into the circulation in small quantity, cause a diminution in the frequency of the jmlse and of the respiratory movements, a lowering of the temperature and arterial tension, and dis- integration of the blood-corpuscles. In large doses (2-4 grams [30-G0 grains] for a dog) they produce the same effects to a more marked degree; epileptiform convulsions, black and bloody urine, and death more or less rapidly. These effects do not follow the injection of the products of decomposition of the biliary acids, except cholic acid, and in that case the symptoms are much less marked. Nor are the biliary acids discharged unaltered with the feces ; they are decomposed in the intestine. The extract, suitably purified, of the contents of the upper part of the small intestine, gives a well-marked reaction with Pettenkofer’s test; while similar extracts of the contents of the lower part of the large intestine, or of the feces, fail to give the reaction, and consequently are free from glyco- or taurocholic, cholic acid, or dyslysin ; the feces, more- over, do not contain either taurine or glycocol. During the processes, at 218 MANUAL OF CHEMISTRY. present but imperfectly understood, which take place in the intestine, the bile-acids are undoubtedly decomposed into cholic acid and taurine or glycocol, which are subsequently reabsorbed, either as such, or after having been subjected to further decomposition; and as a consequence of their decomposition they probably have some influence upon intestinal digestion. The biliary salts are precipitated from their aqueous solution, or from bile, by fresh gastric juice from the same animal; but they are not so precipitated if the gastric juice contain peptone. The proportion of biliary salts in human bile seems to vary considerably, as shown by the following analyses : Mucin Cholesterin Fats ... Taurocholate of sodium, ) Glycocholate of sodium )’ *' Soaps I. ii. hi. IY. V. VI. VII. VIII. IX. 2.66 0.16 0.32 7.22 2.98 0.26 ) 0.92 j 9.14 2.21 4.73 10.79 1.08 82.27 17.73 * 1.45 3.09 5.65 0.63 89.81 10.19 j (425 i 0.04 { 4.48 0.64 3.86 2.48 0.25 0.05 0.75 2.09 0.82 0.46? 90.88 9.12 1.29 0.34 0.36 1.93 0.44 1.63 1.46? 91.08 8.92 1.57 4.90 1.46 1.29 0.35 0.73 0.87 3.03 1.39 Mineral salts "Water Total solids 0.65 S6.00 14.00 0.77 85.92 14.08 I. Frerichs : Bile from man, act. 18, killed by a fall. II. Frerichs: Male, act. 22, died of a wound. III. Gorup-Besanez: Male, act. 49, decapitated IV. Gorup-Be- sanez: Female, set. 29, decapitated. V. Jacobsen: Male, biliary fistula. VI., VII. Trifanowski: Males. VIII. Socolof : Mean of six analyses of human bile. IX. Hoppe- Seyler: Mean of five analyses of bile from subjects with healthy livers. Pathologically, the biliary acids may be detected in the blood and urine in icterus and acute atrophy of the liver, although by no means as frequently as the biliary coloring matters. Creatine—C4H9N3Oa+Aq —131 + 18—is another complex amido-acicl, which occurs as a normal constituent of the juices of muscular tissue, voluntary and involuntary, of brain, blood, and amniotic fluid. It is best obtained from the flesh of the fowl, which contains 0.32 per cent., or from beef-heart, which contains 0.14 per cent., by hashing, warming with alcohol and expressing strongly ; the alcohol is distilled oflj the residual liquid precipitated with lead acetate, filtered, treated with II,,S, again filtered, the filtrate evaporated to a syrup, from which the creatine crystallizes. It is soluble in boiling H„0 and in alcohol, insoluble in ether; crystallizes in brilliant, oblique, rhombic prisms ; neutral, tasteless, loses aq. at 100° (212° F.) ; fuses and decomposes at higher temperatures. When long heated with I I,,O or treated with concentrated acids, it loses H.O, and is converted into creatinine. Baryta water decomposes it into sarcosine and urea. It is not precipitated by silver nitrate, except when it is in excess and in presence of a small quantity of potassium hydrate ; the white precipitate so obtained is soluble in excess of potash, from which a jelly separates which turns black, slowly at ordinary temperatures, rapidly at 1003 (212° F.). A white precipitate, which turns black when heated, is also formed when a solution of creatine is similarly treated with mercuric chloride and potash. COMPOUNDS OF ALCOHOLIC KAD1CALS. 219 Creatinine—C,H7N30—113—a product of the dehydration of crea- tine, is a normal and constant constituent of the urine and amniotic fluid, and also exists in the blood and muscular tissue. It crystallizes in oblique, rhombic prisms, soluble in H.,0 and in hot alcohol; insoluble in ether. It is a strong base, has an alkaline taste and reaction ; expels NII3 from the ammoniacal salts, and forms well-defined salts, among which is the double chloride of zinc and creatinine (C4H.N3 0)aZnCla, obtained in very sparingly soluble, oblique prismatic crystals, when alcoholic solutions of creatinine and zinc chloride are mixed. The quantity of creatinine eliminated is slightly greater than that of uric acid, 0.6-1.3 gram (9.25-20 grains) in 24 hours ; it is not increased by muscular exercise, but is diminished in progressive muscular atrophy. It is obtained from the urine by precipitation with zinc chloride. Xanthine—Xanlhic o.ride—Urous acid—C5H4N’4Oa—152—occurs in a rare form of urinary calculus ; in the pancreas, spleen, liver, thymus, and brain of mammals and fishes; and in human urine after the use of sulphur baths or inunctions. It is an amorphous, yellowish-white powder; very slightly soluble in cold H.,0. If dissolved in HN03 and the solution evaporated, xanthine leaves a yellowish residue, which turns reddish-yellow on the addition of potash solution, and violet-red when heated. Xanthine calculi vary in size from that of a pea to that of a pigeon’s egg. They are rather hard, brownish-yellow, smooth, shining, and made up of well-defined, concentric layers. Their broken surfaces assume a waxy polish when rubbed. Hypoxanthine—Sarcine — C5H4N40—136—odcurs in the spleen, muscular tissue, thymus, suprarenal capsules and brain of mammals ; in the liver in acute yellow atrophy ; and in the blood and urine in leucocy- thsemia. It may be obtained from the mother liquor of the preparation of creatine (q. v.). It forms nodular masses ; soluble in 300 parts of cold, and 78 parts of boiling HaO. It is produced from uric acid or from xanthine by the action of sodium amalgam, and when oxidized by HN03 it yields xanthine. Guanine—C.H.N.O—151—occurs in guano, in the excrements of the lower animals, and in the pancreas, lungs, and liver of certain mam- malians. It is a white or yellowish, amorphous, odorless and tasteless solid; almost insoluble in HsO, alcohol and ether ; readily soluble in acids and alkalies, with which it forms compounds. Carnine—C.H N(03 -f H,0—196 + 18—is obtained from Liebig’s meat extract in chalky, microscopic crystals, readily soluble in warm H.,0. It forms compounds with acids and alkalies, similar to those of hypoxan- thine. COMPOUNDS OF THE ALCOHOLIC RADICALS WITH OTHER ELEMENTS. The organic substances hitherto considered are composed of seven ele- ments only : C, H, O, N, Cl, Br and I; but compounds of C containing every known element have been observed to exist in nature, or have been pro- duced artificially. Of these quite a number may be considered as con- taining the radicals of the series C„H.,„+1, which exist in the monoatomic alcohols. These bodies are almost exclusively the products of the labora- 220 MANUAL OF CHEMISTRY. tory, and resemble in constitution some of the compounds already con- sidered. Sulphides.—The compounds of the alcoholic radicals with S are the same in constitution as those with O, S taking the place of O : C,Hr,) , H'J u 1 o" c„h6 } u C,H ) H ) h C. H. \ OH. f S Ethyl hydrate (alcohol). Ethyl oxide (ether). Ethyl ssulphydrate (mercaptan). Ethyl sulphide. Ethyl Sulphydbate, usually known as mercaptan, from its tendency to unite with mercury (corpus mercurium captains), is formed in a variety of reactions. It is best prepared by treating alcohol with H.,S04, as in the preparation of sulphovinic acid (q. v. ) ; mixing the crude product with excess of potash ; separating from the crystals of potassium sulphate; saturating with H.,S ; and distilling. It is a mobile, colorless liquid ; sp. gr. 0.8325 ; has an intensely disa- greeable odor, combined of those of garlic and H„S ; boils at 3G°.2 (97 .2 F.) ; ignites readily and burns with a blue flame ; may be readily frozen by the cold produced by its own evaporation ; neutral in reaction ; sparingly soluble in H.,0, soluble in all proportions in alcohol and ether ; dissolves I, S and P. Potassium and sodium act with mercaptan as with alcohol, replacing the extra-radical hydrogen. In its behavior toward the oxides it more closely resembles the acids than the alcohols, being capable even of enter- ing into double decomposition to form salts, called mlphethylates or mer- captides. Its action with mercuric oxide is characteristic, forming a white, crystalline sulphide of ethyl and mercury : 2(0’h1S) + Hn 0 = (C Hg’;fS= + H-° Ethyl snlphydrate. Mercuric oxide. Ethji-mercuric sulphide. Water. Ethyl Sulphide, a colorless liquid ; having a penetrating, disagreeable odor of garlic ; boiling at 73° (1(53°.4F.) ; insoluble in H.O, soluble in alcohol; inflammable ; obtained by the action of ethyl chloride upon potassium sulphide. Phosphines, arsines, and stibines are compounds resembling the amines in constitution, in which the N is replaced by P, As, or Sb. Like the amines, they may be primary, secondary, or tertiary : C..H ) H - N H) C.H ) H-P Hi CJP) -As ■h\ CM:) C.H. -Sb. c;h;;\ Ethylamine (primary). Ethylphospine (primary'). Uiethyl-arsine (secondary). Triethyl-stibine (tertiary). There also exist compounds containing P, As, or Sb, which are similar in constitution to the hydrates and salts of ammonium, and of the com- pound ammoniums : nh4i N(CH3)4I As(CH3)4I Ammonium iodide. Tetramethyl ammonium iodide. Tetramethyl arsenium iodide. ALLY LIC SERIES. Most of these compounds, which are very numerous, are as yet only of'theoretic interest. One of them, however, is deserving of notice here : CH,) Dimethyl Aksine, CH - As—106—which may he considered as being h) the hydride of the radical [As(CHs)J, does not exist as such ; there is however, a liquid known as the fuming liquor of Cadet, or alkarsin, which is obtained by distilling a mixture of potassium acetate and arsenic trioxide. This liquid contains the oxide of the above radical, and a sub- stance which ignites on contact with air, and which consists of the same radi- cal united to itself 2[As(CH3)„]. This radical, called cacodyle (kuk6<; = evil), is capable of entering into a great number of other combinations. Cacodyle and its compounds are all exceedingly poisonous, especially the cyanide, an ethereal liquid, very volatile, the presence of whose vapor in inspired air, even in minute traces, produces symptoms referable both to arsenic and to hydrocyanic acid. Organo-metallic substances are compounds of the alcoholic radi- cals with metals. They are very numerous, usually obtained by the action of the iodide of the alcoholic radical upon the metallic element, in an atmosphere of H. They are substances which, although they have been put to no uses in the arts or in medicine, have been of great service in chemical research. As typical of this class of substances we may men- tion : Zinc-ethyl—\ Zn—123—obtained by heating at 130° (266° F.) in a sealed tube a mixture of perfectly dry zinc amalgam with ethyl iodide ; the contents of the tube are then distilled in an atmosphere of coal-gas, or H, and the distillate collected in a receiver, in which it can be sealed byr fusion of the glass without contact with air. It is a colorless, transparent, highly refracting liquid; sp. gr. 1.182 ; boils at 118° (244 .4 F.). On contact Avith air it ignites and burns with a luminous flame, bordered with green, and gives off dense clouds of zinc oxide, a property’ which renders it very dangerous to handle. On contact with H,0 it is immediately decomposed into zinc hydrate and ethyl hydride. It is chiefly’ useful as an agent by which the radical ethyl can be introduced into organic molecules. ALLYLIC SERIES. The compounds heretofore considered may be derived more or less directly from the saturated hydrocarbons ; in the derivatives, as in the hydrocarbons, the valences of the C atoms are all satisfied, and that in the simplest and most complete manner, two neighboring C atoms always exchanging a single valence. There exist, however, other compounds, containing less H in proportion to C than those already considered, and yet resembling them in being monoatomic. These compounds have usually been considered as non-saturated, because all the possible valences are not satisfied, and the substances are therefor capable of forming pro- ducts of addition, while the saturated compounds can only form products of substitution. In this sense the substances composing this series are non-saturated, but they are not so in the sense that they contain C or other atoms whose valences are not satisfied. The following formula? indicate the constitu- MANUAL OF CHEMISTRY. tion of the substances of this series, and their relation to those of the pre- vious one. It will be observed that in the allyl compounds two neighbor- ing C atoms exchange two valences : ch3 ch2 CH,H CH, ch2 I CH2OH CH3 I CH., I COH CH, I CH, I COOH f CH, I CH, I CH2 I or or or or ( or c.„h5 ) c3h6 f (C-H^}o or (° i O. 226 MANUAL OF CHEMISTRY. C H O ) Oleic acid—Acidum oleicum (U. S.)— 18 33jj - O—246—exists as its glyceric ether, olein, in most, if not in all the fats and in all fixed oils. It is obtained in an impure form on a large scale as a by-product in the manufacture of candles. This product is, however, very impure ; to purify it, it is first cooled to 0° (32° F.), the liquid portion collected ; cooled to —10° (14° F.), expressed, and the solid portion collected ; this is melted and treated with half its weight of massicot; the lead oleate so obtained is dissolved out by ether ; the decanted ethereal solution is shaken with HC1, the ethereal layer decanted and evaporated, when it leaves oleic acid, contaminated with a small quantity of oxyoleic acid, from which it can be purified only by a tedious process. Pure oleic acid is a white, pearly, crystalline solid, which fuses to a colorless liquid at 14° (57°.2 F.); it is odorless and tasteless ; soluble in alcohol, ether, and cold H,,S04; insoluble in H„0 ; sp. gr. 0.808 at 19° (66°.2 F.). Neutral in reaction. It can be distilled in vacuo without decom- position, but when heated in contact with air, it is decomposed with formation of hydrocarbons, volatile fatty acids, and sebacic acid. It dis- solves the fatty acids readily, forming mixtures whose consistency varies with the proportions of liquid and solid acid which they contain. The solid acid is but little altered by exposure to air, but when liquid it absorbs O rapidly, becomes yellow, rancid, acid in reaction, and incapable of solidifying when cooled ; these changes take place the more rapidly the higher the temperature. Cl and Br attack oleic acid with formation of products of substitution. If oleic acid be heated with an excess of caustic potassa to 200° (392° F.), it is decomposed into palmitic and acetic acids ; Clf,H, 402 -f 2KHO = c16h31o2k + C2H302K -h H ,; a reaction which is utilized industrially to obtain hard soaps, palmitates, from olein, which itself only forms soft soaps. Cold H.,S04 dissolves oleic acid, and deposits it unaltered on the addition of H20, but if the acid solution be heated it tm-ns brown and gives off S02. Nitric acid oxidizes it energetically, with formation of a number of volatile fatty acids and acids of another series—suberic, adipic, etc. The oleates of the alkaline metals are soft, soluble soaps ; those of the earthy metals are insoluble in H.,0, but soluble in alcohol and in ether. Elaidic acid is an isomere of oleic acid, produced by the action upon it of nitrous acid in the preparation of Unguentum hydrargyri nitratis (U. S. : Br.). The nitrous fumes formed convert the oleic acid, contained in the oil and lard used, into elaidic acid, which exists in the ointment in combination with mercury. POLYATOMIC COMPOUNDS. The organic compounds hitherto considered may be looked upon as compounds of univalent carbon radicals, these radicals existing in the al- cohols and acids in combination with an atom each of O and H ; they are called monoatomic because they contain a single atom of H capable of being replaced by an alcoholic radical. There exist other C compounds, in which the radicals, containing a less number of H atoms as compared with the number of C atoms, have a valence greater than one ; these radi- cals form acids, alcohols, etc., in which the number of atoms of replaceable H is greater than one, and which are designated as polyatomic. HYDROCARBONS, 1st Series. 2d Series. C„Hin 3d Series. 4th Series. CwHan_4 5tii Series. C„Ha„_e 6th Seiues. (i TT 7tii Series. C„Han„l0 8th Series. CM,^ 9th Series. C„H2n_14 IOtii Series. c„h2„_16 11 th Series. C,Hn_18 OH, Methane. C,Ha C2H4 O2H2 Ettiane. Ethene. Acetylene. C3H« C3H0 C3H4 Propane. Propene. AUylene. C1H10 C,H« C1H0 C4H4 Butane. Butene. Crotonylene. C5H18 CaHxo O0H« c6h„ Pentane. Pentene. Valery lene. Valylene. C0Hh CeH.2 CeHio C6Hh C0He Hexane. Hexene. Hexylene. Benzene. c,h16 o,h14 C7H,2 C7H10 C,H« Heptane. Heptene. (Enanthylidene Toluene. CsHis c*h16 c«h14 C8H,2 aH10 CgH* Octane. Octene. Caprylidene. Xylene. Cinnamene. CaH,o CaHig OoHja c„h14 C3H,2 C„Hio Nonane. Nonene. Cumene. C10H22 C10H20 CioHib C.oHxo Ol oHh C,oH,2 CloHlO CioHs Decane. Decene. Decenylene. Terebenthene. Cymene. Naphthydrene. Naphthalene. Oi 1H24 OilU 2 2* C11H20 C„H1S CnH18 OuH14 0UHl2 C11H10 Undecane. Undecene. Laurene. C12H20 01 2H2 4 O12H22 C12H18 c12h16 cishI4 C12H12 C12H10 Dodecane. Dodecene. Acenaphthalene. O13H28 Tridecane. C13H26 Tridecene. C13H34 Ol 3H32 Ol3H20 013H18 c,3h,8 C13H14 C13H;2 Ci3Hio Fluorene. C14H3^ Tetradecane. ChH2« Tetradecene. C14H26 014H24 Ol4H22 C14H3o Cl4H,8 CuHxe C14Hu C1 4 H 1 2 Stilbene. C14H,o Anthracene. HYDliOCAllBONS. 228 MANUAL OF CHEMISTRY. NON-SATURATED HYDROCARBONS. Besides the compounds of C and H described on pp. 172 et seq., in which all the valences of the C atoms are satisfied, either by the attachment of H atoms, or by the interchange of a single valence between neighboring C atoms, there exist many others in which the proportion of H to C is less. These compounds are non-saturated, in this, that they are capable of unit- ing directly with atoms of other elements, or with radicals, to form pro- ducts of addition, while the composition of the saturated hydrocarbons can only be modified by substitution ; they are not, however, to be consid- ered as containing any unsatisfied valence. These hydrocarbons are very numerous, and may be arranged in ho- mologous sei’ies, as shown in the table on page 227, each succeeding series containing a less amount of H in proportion to the C : SECOND SERIES OF HYDROCARBONS—OLEFINES. Series C„H.„. The terms of this series contain two H atoms less than the correspond- ing terms of the first series ; they differ in constitution in this, that, while in the first series a single valence is exchanged between each two neighboring C atoms, in the second series two valences are exchanged be- tween two of the C atoms : c=h3 I C=tH2 I CfEH3 C_H, I C-H II c=H2 They are designated as olefines ; or, to distinguish them from the terms of the first series, by the terminations ylene or ene, thus the second is called ethylene or ethene. They behave as bivalent radicals. Ethene—Ethylene—Olefiant gas—Elayl—Heavy carburetted hydro- CH> gen— || —28—is formed by the dry distillation of fats, resins, wood, CH, and coal, and is one of the most important constituents of illuminating gas. It is also obtained by the dehydration of alcohol or ether. It has been obtained synthetically: (1) by passing a mixture of H.,S and carbon monoxide over iron or copper heated to redness; (2) by heat- ing acetylene in the presence of H, or by the action of nascent H upon copper acetylide ; (3) by the action of H upon the chloride C„C1,, obtained by the action of Cl upon carbon disulphide. It is prepared in the labora- tory by the dehydration of alcohol: a mixture of 4 pts. H2S04 and 1 pt. alcohol is placed in a flask containing enough sand to form a thin paste, and gradually heated to about 170° (338° F.) ; the gas, which is given off in abundance, is purified by causing it to pass through wash-bottles con- taining H20, an alkaline solution, and concentrated H.,S04. Propane. Propylene. DIATOMIC ALCOHOLS. 229 Pure ethylene is a colorless gas ; tasteless ; has a faint odor resembling that of salt water, or an ethereal odor when impure ; irrespirable ; spar- ingly soluble in H„0, more soluble in alcohol. It burns with a luminous, white flame, and forms explosive mixtures with air and oxygen. When heated for some time at a dull red heat it is converted into acetylene, ethyl and methyl hydrides, a tarry product, and carbon. Ethylene readily enters into combination. It unites with H to form ethyl hydride, C4HB. With O it unites explosively on the approach of a flame, with formation of carbon dioxide and H,,0. Oxidizing agents, such as potassium permanganate in alkaline solution, convert it into oxalic acid and HsO. A mixture of Cl and ethene, in the proportion of two volumes of the former to one of the lattei-, unite with an explosion on contact with flame, the union being attended with a copious deposition of C and the formation of HC1. Chlorine and ethene, mixed in equal volumes and ex- posed to diffused daylight, unite slowly, with formation of an oily liquid ; ethene chloride, C,H4C1, = Dutch liquid, to whose formation ethene owes the name olefiant gas. By suitable means ethene may also be made to yield chlorinated products of substitution, the highest of which is carbon dichlorule, C.4C14. Br and I also form products of addition and of substitu- tion with ethene. By union with (OH)2 it forms glycol (q. v.). It slowly dissolves in ordinary H.,S04, with formation of sulphovinic acid ; with fuming H„S04 it combines with elevation of temperature and formation of ethionic anhydride. When inhaled, diluted with air, ethene produces effects somewhat similar to those of nitrous oxide. Pentene— A mylene or valerene—C5H10—70—a colorless, mobile liquid, boiling at 39° (102°.2 F.) ; obtained by heating alcohol with a concentrated solution of zinc chloride. Its use as an anaesthetic has been suggested. CH.C1 Ethene chloride—Bichloride of ethylene—Dutch liquid— | —99 CH2C1 —is obtained by passing a current of ethene through a retort in which Cl is being generated, and connected with a cooled receiver. The dis- tillate is washed with a solution of caustic potassa, afterward with H.,0, and is Anally rectified. It is a coloi’less, oily liquid, which boils at 82.5° (180°. 5 F.); has a sweet- ish taste and an ethereal odor. It is isomeric with the chloride of mo- C2H4C1 nochlorinated ethyl, | , which boils at 64° (147°.2 F.). It is capable Cl of fixing other atoms of Cl by substitution for H, and thus forming a series of cliloi-in ited derivatives, the highest of which is C .Cb. DIATOMIC ALCOHOLS. Series C„Hn+ 00 These substances are usually designated as glycols. They are the hydrates of the hydrocarbons of the series C„H.,n, and consist of those hydrocarbons, playing the part of bivalent radicals, united with two groups OH ; their general typical formula is then (C„H2„)" ) q have seen (p. 178) that the primary monoatomic alcohols contain the group of 230 MANUAL OF CHEMISTRY. atoms (CH2OH), united with n(C<1H2„^1); the primary glycols are simi, larly constructed, and consist of twice the group (CH.OH), united in the higher terms to n(CH.,). The constitution of the glycols and their rela- tions to the monoatomic alcohols are indicated by the following formulae: CH,OH I ch2 I ch3 CH.OH I CH I CH.OH Primary propyl alcohol. Primary propyl glycol As the monoatomic alcohols are such by containing in their molecules a group (OH), closely attached to an electro-positive group, and capable of removal and replacement by an electro-negative group or atom, so the glycols are diatomic by the fact that they contain two such groups (OH). As the monoatomic alcohols are therefor only capable of forming a single ether with a monobasic acid, the glycols are capable of forming two such ethers: CH., (C.,H302)' I CH, CH,, (C.H.OJ' I CH.OH CH, (C2H30) I CH, (C.H;().J Ethyl acetate Monoacetic glycol. Diacetic glycol. CH.OH Ethene glycol—Ethylene glycol or Alcohol or Hydrate— | CH2OH 02.—This, the best known of the glycols, is prepared by the action of dry silver acetate upon ethylene bromide. The ether so obtained is purified by redistillation, and decomposed by heating for some time with barium hydrate. It is a colorless, slightly viscous liquid ; odorless ; faintly sweet ; sp. gr. 1.125 at 0° (32° F.); boils at 197° (386°.6 F.) ; sparingly soluble in ether; very soluble in water and in alcohol. It is not oxidized by simple exposure to air, but on contact with plati- num black it is oxidized to glycolic acid ; more energetic oxidants trans- form it into oxalic acid. Chlorine acts slowly upon glycol in the cold ; more rapidly under the influence of heat, producing chlorinated and other derivatives. By the action of dry HC1 upon cooled glycol, a product is formed, intermediate between it and ethylene chloride, a neutral eom- CH..OH pound—ethene chlorhydrate or ethene chlorhydrin, | , which boils at CH.Cl 130° (266° F.). Ethene oxide—Ethylene oxide— (C2H4)"0 —44.—This substance, iso- meric with aldehyde, is obtained by the action of potassium hydrate upon ethene chlorhydrate. It is a transparent, volatile liquid ; boils at 13°.5 (54°.3 F.) ; gives off inflammable vapors ; mixes with H.,0 in all proportions. It is capable of uniting directly with H.,0 to form glycol ; and with HC1 gas to regenerate ethene chlorhydrate. Taurine—SO.C H.N—125—is isomeric with a derivative of glycol, isethionamide. It is obtained from ox-bile by boiling with dilute HC1 ; ACIDS DERIVED FROM TIIE GLYCOLS. decanting and concentrating the liquid ; separating from the sodium chlo- ride which crystallizes ; evaporating further, and precipitating with alco- hol. The deposit is purified by recrystallization from alcohol. It crystallizes in large, transparent, oblique, rhombic prisms, permanent in air, soluble in HaO, almost insoluble in absolute alcohol and ether. Taurine has acid properties and forms salts ; it is not attacked by H„S04, HNO„, or nitromuriatic acid, but is oxidized by nitrous acid, with formation of H,0, N, and isetliionic acid. It exists in the animal economy, in the bile in taurocliolic acid (q. v.) ; and has also been detected in the intestine and faeces, muscle, blood, liver, kidneys, and lungs. The pneumic acid, described as existing in the lung, is taurine. When taken internally, it is eliminated by the urine, not in its own form, but as taurocarbamic or isethionuric acid, C H N.,SO . ACIDS DERIVED FROM THE GLYCOLS. As the acids of the acetic series are obtained from the primary mono- atomic alcohols by the substitution of 0 for H„ in the characterizing group CH .OH: ch3 I CH,OH ch3 CO, OH Ethyl alcohol. Acetic acid. so the diatomic alcohols may, by oxidation, be made to yield acids, formed by the same substitution of O for H,. But the glycols differ from the monoatomic alcohols in containing two groups CH„OH, and they con- sequently yield two acids, as the substitution occurs in one or both of the alcoholic groups : ch2,oh I CH„OH CH,.OH I CO, OH CO, OH I CO, OH A study of these two acids shows them to be possessed of peculiar differences of function. Each of them contains two groups (OH), Avhose hydrogen is capable of replacement by an acid or alcoholic radical : Ethene glycol. Glycolic acid. Oxalic acid ch„oc.,h5 I COOH CH„OH I CO,OC2H5 CH.OC.H. I co,oc2h:) CO,OH C0,0'C.2H CO,OC.,H I CO,OC.,H. Ethylglycolic acid. Ethyl glycolate. Ethyl etliylglycolate. Ethyloxalic acid. Ethyl oxalate. They are, therefor, both said to be diatomic. The ability, however, of the two acids to form salts is not the same, for while oxalic acid is capable of forming two salts of univalent metals, and a salt of a bivalent metal with a single molecule of the acid ; glycolic acid only forms a single salt of an univalent metal, and two of its molecules are required to form a salt of a bivalent metal ; in other words, glycolic acid is monobasic while oxalic acid is dibasic. It is only that H atom which is contained in the electro-nega- tive group COOH, which is replaceable as acid hydrogen, while that of 232 MANUAL OP CHEMISTRY. the electro-positive group CH2OH is only replaceable, as is the correspond- ing hydrogen of an alcohol. In general terms, therefor, the atomicity of an organic acid may be greater than its basicity, the former representing the number of H atoms contained in its molecule, which are capable of being displaced by alco- holic radicals, while the latter represents the number of H atoms re- placeable by electro-positive elements or radicals, with formation of salts or of ethers. There may, therefor, be obtained from the glycols, by more or less complete oxidation, two series of acids; those of the first are diatomic and monobasic ; those of the second diatomic and dibasic. DIATOMIC AND MONOBASIC ACIDS. Series ChH2»03. The acids of this series at present known are (Carbonic acid) C03H2 I Glycolic acid C203H4 Ethyieno-lactic acid C3O3H0 | Eutylactic acid C403H8 Oxyvaleric acid C6O3H10 Leucic acid C603H12 (?) CEnanthic acid C1403H28 The first-named of these acids, although not capable, so far as yet known, of existing in the free state, is widely represented in nature in the shape of its salts, the carbonates. Its position in this series is an anomaly, and at first sight a contradiction, as it is certainly not a mono- basic, but a distinctly dibasic acid, or, more properly speaking, would be such -were it obtained in a state of purity. It is, however, in this position, as the inferior liomologue of glycolic acid, that carbonic acid is most naturally placed, and the dibasic nature of the latter acid does not pre- sent any valid objection to such a position, for if we consider one term of a series as derivable from its superior liomologue by the subtraction of CH,, and if we bear in mind that the basic nature of the hydrogen atom in a group OH depends upon its close union with the group CO (or with some other electro-negative group), it will become evident that the in- ferior liomologue of glycolic acid must contain two groups OH united to one CO, and must, therefor, be dibasic: CH.OH OH /nTT I — CH2 = I or CO,OH CO,OH xwri CO,OH Glycolic acid. Carbonic acid. The other acids of the series are formed : (1.) By the partial oxidation of the corresponding glycol : CH.OH CH.OH I + O, = I ‘ + 5>o CH2OH CO, oh Glycol. Glycolic acid. Water. OXIDES OF CABBON. 233 (2.) By the combined action of water and silver oxide upon the mono- chlor-acid of the acetic series, or by heating the alkaline salt of such an acid with water or potassium hydrate : CH„C1 „ CH20H | ' + 5)0 =| + KC1 COOK CO,OH Potassium monochloracetate. Water Glycolic acid. Potassium chloride. (3.) By reducing the corresponding acid of the oxalic series by nascent hydrogen : coofi CH2OH w I + 2H2 = I + 5)0 C00H C00H Oxalic acid. Glycolic acid. Water. Carbonic acid—CO( —62.—Although this acid has not been ated, it probably exists in aqueous solutions of C02, which have an acid ffion, while dry CO, is neutral. Its salts, the carbonates, are well char- jrized. isolated, it probably exists in aqueous solutions of C02, which have an acid reaction, while dry C02 is neutral. Its salts, the carbonates, are well char- acterized. Oxides of Carbon. Carbon monoxide—Carbonous oxide—Carbonic oxide—CO—28. Formation.—(1.) By burning C with a limited supply of air. (2.) By passing dry carbon dioxide over red-hot charcoal. (3.) By heating oxalic acid with H,S04 : C204H, = HO -f- CO + C02; and passing the gas through sodic hydrate to separate CO,. (4.) By heating potassium ferrocyanide with H2S04. Properties.—A colorless, tasteless gas; sp. gr. 0.9678A ; very sparingly soluble in H,0 and in alcohol. 11 burns in air with a blue flame and formation of carbon dioxide ; it forms explosive mixtures with air and oxygen ; it is oxidized to carbon dioxide by cold chromic acid. It is a valuable reducing agent, and is used for the reduction of metallic oxides at a red heat. Ammoniacal solutions of the cuprous salts absorb it readily. Being lion-saturated, it unites readily with O to form C02, and with Cl to form COCl2, the latter a colorless, suf- focating gas, known as phosgene, or carbonyl chloride. Toxicology.—Carbon monoxide is an exceedingly poisonous gas, and is the chief toxic constituent of the gases given off from blast-furnaces, from defective flues, and open coal or charcoal fires, and of illuminating gas. An atmosphere containing but a small proportion of this gas pro- duces asphyxia and death, even if the quantity of oxygen present be equal to or even greater than that normally existing in the atmosphere ; 0.5 per cent, of CO in air is sufficient to kill a small bird in a few moments, and one per cent, proves fatal to small mammals. Poisoning by CO may occur in several ways. By inhalation of the gases discharged from blast-furnaces and from copper-furnaces, the former con- taining 25 to 32 per cent., and the latter 13 to 19 per cent, of CO. By the fumes given off from charcoal burned in a confined space, which con- sist of a mixture of the two oxides of carbon, the dioxide predominating 234 MANUAL OF CHEMISTRY. largely, especially when the combustion is most active. The following is the composition of an atmosphere produced by burning charcoal in a con- fined space, and which proved rapidly fatal to a dog : oxygen. 19. ID ; nitro- gen, 7G.G2 ; carbon dioxide, 4.G1 ; carbon monoxide, 0.54; marsh-gas, 0.04. Obviously the deleterious effects of charcoal-fumes are more rapidly fatal in proportion as the combustion is imperfect and the room small and ill-ventilated. A fruitful source of CO poisoning, sometimes fatal, but more frequently producing languor, headache, and debility, is to be found in the stoves, furnaces, etc., used in heating our dwellings and other buildings, especially when the fuel is anthracite coal. This fuel produces in its combustion, when the air-supply is not abundant, considerable quantities of CO, to which a further addition may be made by a reduction of the dioxide, also formed, in passing over red-hot iron ; this poisonous gas may find its way into the rooms either through cracks or other defects in the stoves, flues, or pipes ; by occasional downward currents of air passing over fires in open fireplaces, or, much more frequently, by direct passage through the heated metal. Experiment has shown that metals, notably cast-iron, are quite pervious to gases when heated to redness ; when, therefor, a stove or the fire-box of a hot-air furnace becomes red-hot, a portion of the gases, formed by the combustion of the fuel, passes through the pores of the metal to contaminate the air without, and gives rise to CO poisoning to a degree depending upon the degree of imperfection of the ventilation, the nature of the fuel, and the amount of air supplied to it. The precautions required to avoid this form of what may be called chronic CO poisoning, and which is by no means uncommon, are: (1) To have the stoves or furnaces lined with fire-clay, which tends to prevent their overheating and to diminish their perviousness to gases ; (2) to avoid heating to redness ; (3) to furnish an abundant supply of air to the fuel; (4) to secure proper ventilation ; and (5), in the case of hot-air furnaces, to obtain, by an abun- dant supply of external air to the air-chamber, a large supply of moderately heated air rather than a small quantity of very hot air. Of late years cases of fatal poisoning by coal-gas are of very frequent occurrence, caused either by accidental inhalation, by inexperienced per- sons blowing out the gas, or by suicides. The most actively poisonous in- gredient of coal-gas is CO, which exists in the ordinary illuminating gas in the proportion of 4 to 7.5 per cent., and in water-gas, made by decompos- ing superheated steam by passage over red-hot coke, and subsequent charging with vapor of hydrocarbons, in the large proportion of 30-35 per cent. The method in which CO produces its fatal effects is by forming with the blood-coloring matter a compound which is more stable than oxyhemo- globin, and thus causing asphyxia by destroying the power of the blood- corpuscles of carrying O from the air to the tissues. This compound of CO and hemoglobin is quite stable, and hence the symptoms of this form of poisoning are very persistent, lasting until the place of the coloring-mat- ter thus rendered useless is supplied by new-formation. The prognosis is very unfavorable when the amount of the gas inhaled has been at all con- siderable ; the treatment usually followed, i.e., artificial respiration, and inhalation of O, failing to restore the altered coloring-matter. There would seem to be no form of poisoning in which transfusion of blood is more directly indicated than in that by CO. Detection after death.— The blood of those asphyxiated by CO is per- sistently bright red in color. When suitably diluted and examined with OXIDES OF CAKBOJST. 235 the spectroscope, it presents an absorption spectrum (Fig. 35) of two bands similar to that of oxyhsemoglobin (Fig. 14, No. 11) but in which the two bands are more equal and somewhat nearer the violet end of the spectrum. Owing to the greater stability of the CO compound, its spectrum may be readily distinguished from that of the O compound by the addition of a reducing agent (an ammoniacal solution of ferrous tartrate), which changes the spectrum of oxyluemoglobin to the single-band spectrum of haemo- globin (Fig. 14, No. 12), while that of the CO compound remains unaltered, or only fades partially. If a solution of caustic soda of sp. gr. 1.3 be added to normal blood, a black, slimy mass is formed, which, when spread upon a white plate, has a greenish-brown color ; the same reagent added to blood altered by CO forms a firmly clotted mass, which in thin layers upon a white surface is bright red in color. Fig. 35. For the method of detecting and determining CO in gaseous mixtures, see p. 243. Carbon dioxide—Carbonic anhydride—Carbonic acid gas—CO,—44. Preparation.—(1.) By burning C in air or O. (2.) By decomposing a carbonate (marble = CaC03) by a mineral acid (HC1 diluted with an equal volume of H.O). Propertied—At ordinary temperatures and pressures it is a colorless, suffocating gas ; has an acidulous taste ; sp. gr. 1.529A ; soluble in an equal volume of HO at the ordinary pressure; much more soluble as the pressure increases. Soda water is a solution of carbonic acid in H .O under increased pressure. When compressed to the extent of 38 atmospheres at 0° (32° F.); 50 atm. at 15° (59° F.); or 73 atm. at 30° (8G°F.) it forms a transparent, mobile liquid, by whose evaporation, when the pressure is relieved, sufficient cold is produced to solidify a portion into a snow-like mass, which by spontaneous evaporation in air, produces a temperature of -90° (-130° F.). Carbon dioxide neither burns nor does it support combustion. When heated to 1,300° (2,370° F.), it is decomposed into CO and O. A similar de- composition is brought about by the passage through it of electric sparks. When heated with H it yields CO and H20. When Iv, Na or Mg is heated in an atmosphere of CO„, the gas is decomposed with formation of a car- bonate and separation of carbon. When caused to pass through solutions of the hydrates of Na, K, Ca, or Ba, it is absorbed, with formation of the carbonates of those elements, which, in the case of the last two, are de- posited as white precipitates. Solution of potash is frequently used in analysis to absorb C00, and lime and baryta water as tests for its presence. The hydrates mentioned also absorb CO„ from moist air. Atmospheric Carbon Dioxide. — Carbon dioxide is a constant constituent of atmospheric air in small and varying quantities ; the mean amount in free country air being about 4 in 10.000. The variations in amount under different conditions is shown in the following table : 236 MANUAL OF CHEMISTRY. Amount of Carbon Dioxide in Air. Collected at Parts in 10,000. Determined by Paris 8.190 Boussingault and Lewy. Boussingault and Lewy. Boussingault. Boussingault. Lewy. Lewy. Saussure. Andiliv—twenty miles from Paris 2.989 Paris—Day 8.9 Night 4.2 Ocean—Day 5.42 Night. 8.846 Geneva 4.68 Meadow—three-fourths mile from Geneva : Dry months 4.79 to 5.18 Saussure. After long rains 8.57 to 4.56 Saussure. December, damp and cloudy January, frost 3.85 to 4.25 4.57 Saussure. Saussure. January, thaw 4.27 Saussure. Lake Geneva 4.39 Saussure." Arctic regions 4.83 to 6.41 Moss. Gosport barracks 6.45 Chaumont. Anglesey barracks 14.04 Chaumont. Hilsey Hospital 4.72 Chaumont. Portsmouth Hospital 9.76 Chaumont. Cell in Pentonville Prison 9 89 Chaumont. Cell in Chatham Prison 16.91 Chaumont. Boys’ school—69 cubic feet per head 31.0 Roscoe. Room—51 cubic feet per head 52.8 Weaver. Girls’ school—150 cubic feet per head 72.3 Pettenkofer. Greenhouse—Jardin des Plantes 1.0 Theatre—Parquet 23.0 Near ceiling: 43.0 Lead mine—Lamps burn 80.0 F. Leblanc. Lamps extinguished 390.0 F. Leblanc. Grotto del Cane 7,360.0 F. Leblanc. It will be observed that on land the amount is greater by night than by day, while the reverse is the case at sea; on land the green parts of plants absorb CO„ during the hours of sunlight, but not during those of darkness. The increase in the amount in air over large bodies of water during the daytime is due to the less solubility of CO., in the surface- water when heated by the sun’s rays. The absence of vegetation accounts for the large quantity of CO„ in the air of the polar regions, and the same cause, aided by an increased production, for its excess in the air of cities over that of the country. The sources of atmospheric C02 are : (1.) The respiration of animals.—The air expired from the lungs of animals contains a quantity of C0o, varying with the age, sex, food, and muscular development and activity, while, at the same time, a much smaller quantity is discharged by the skin and in solution in the urine. In females the increase of elimination follows the same rule as with males until puberty, when it ceases, and the amount exhaled remains about the same until the menopause, when the elimination of CO,, suddenly in- creases to nearly the same as that occurring in males of the same age, and subsequently gradually declines with advancing age. During pregnancy the elimination of CO„ is temporarily increased. In both sexes and at all ages the exhalation of CO., is greater during muscular activity than when the individual is at rest, and greater in those whose muscular development is more perfect. An adult man discharges 20.77 litres = three-fourths cubic foot, of C02 per hour, or 498.88 litres = 18 cubic feet, per diem. OXIDES OF CARBON. The following table, from the experiments of Andral and Gavarret, indi- cates the quantity of C02 eliminated by males of various ages : Elimination of Carbon Dioxide. Age. Mean weight. Carbon elim- inated, in grams. Carbon diox- ide elimina- ted,in grams Oxygen a b-1 sorbed, in grams. __ Carbon diox- ide elimina- ted, in litres. Oxygen ab- sorbed, in litres. In In 1 In 24 Ini In 24 In 1 In 24 In 1 In 24 In 1 In 24 kilos. hour. hours. hour. hours. hour. hours. hour. hours. hour. hours. 8 years 22 26 49.07 5.0 120.8 18.3 442.9 15.613 374.70 9. SO 225.16 8.63 207.22 15 years 46 41 102.32 1 8.7 208 8 31.9 765.6 27.166 651.98 16.21 389 22 18.91 453.89 16 years 53.36 117.70 10.3 259 2 39.6 950.4 33.723 809.36 20.13 483.17 23.48 563.42 18 to 20 years 60.88 134.22 114 273.6 41.8 1003.2 35.599 864.32 21.25 510.01 24.78 594.79 20 to 24 years 66.90 147.49 12.2 292.8 44 7 1073.6 38.094 914.28 22.72 545.81 26.52 636.47 40 to 60 years 67.15 148.04 10.1 242.4 37.0 888.8 31.537 756.89 18.81 451.85 21.95 526 92 60 to 80 years 03.35 139.66 9 2 220.8 33.7 809.6 28.727 689.45 17.13 411.59 211.00 479.98 The expired air under ordinary conditions contains about 4.5 per cent, by volume of C02, the proportion being1 greater the slower the respiration. (2.) Combustion.—The greater part of the atmospheric COa is a pro- duct of the oxidation of C in some form as a source of light and heat. In the following table are given the amounts of CO., produced, and of air consumed, by different kinds of fuel and illuminating materials ; by com- paring them with the quantities of the same gases produced and consumed by an adult man it will be seen that, in equal times, an ordinary gas-burner produces nearly six times as much CO,, and consumes nearly ten times as much air as a man. The amount of air consumed by fuel is, for practical pur- poses, greater than that given in the table, as the oxidation is never com- plete, the air in the chimney frequently containing ten per cent, of oxygen by volume (see below). .£ 8 fl u Average per- centage of Carbon dioxide duced by pro- Air deoxidized by | Fuel. g © 3 .£ © one hour. -|o\ m oi in cubic In one hour. _g S Average one hou Carbon. Hydrogen. One volun limes. t! c3 £ O CJ o In kilos. In litres. One Yolur limes. One kilo metres. In kilos. In litres. Heat unit .£ -u SI (■H Carbon to C02 100.0 100.0 3.65 .... 2.39 26.89 9.83 34462 8080 Carbon to CO 100 0 4.93 2474 Carbon monoxide ... 42.80 1.0 1.57 2.39 0.44 2403 75.0 25.09 1.0 2.75 9.55 13.45 13063 85.72 14.2S 2.0 3.14 .... 14.33 12.67 11857 Coal-gas 140 litres 40.0 65.0 0.80 1.67 0.221 112 7.14 11.04 1.293 1000 11000 Crude petroleum.... 84.0 13.0 3.08 12.07 0.235 is* 11775 15 gr. 87.0 13.0 3.17 0.048 25 12.12 11055 iso 10 gr. 79.2 13.2 2.89 0.029 15 11.24 0.146 113 10496 100 Stearic acid 10 gr. 76.05 12.68 2.9 0.029 15 8.69 0.112 86.9 9716 84 Colza-oil 42 gr. 70.43 10.5 2.81 0.118 60 8.28 0.450 348 159 Wood (dry pine) 39.10 4.90 1.43 .... 5.16 3600 Wood charcoal 85.0 3.10 8.36 7640 45.0 1.5 1.64 4.82 3000 87.0 3.17 8.55 Anthracite 90.0 2.5 3.2!) 9.22 6000 52.17 13.04 1.90 * 8.64 7183 Adult man 10 gr. C. 0.037 19 0.1.14 104 Combustion of Fuel. 238 MANUAL OF CHEMISTItY. (3.) Fermentation.—Most fermentations, including putrefactive changes, are attended by the liberation of CO,; thus, alcoholic fermentation takes place according to the equation : CrH190. = £C2H0O + 2CO, 180 92 44 and consequently discharges into the air 44 parts by weight of CO., for every 92 parts of alcohol formed, or 191.5 litres of gas for every litre of absolute alcohol obtained. (4.) Tellural sources.—Volcanoes in activity discharge enormous quan- tities of CO., and, in volcanic countries, the same gas is thrown out abun- dantly through fissures in the earth. All waters, sweet and mineral, hold this gas in solution, and those which have become charged with it under pressure in the earth’s crust, upon being relieved of the pressure when they reach the surface, discharge the excess into the air. (5.) Manufacturing processes.—Large quantities of C02 are added to the air in the vicinity of lime- and brick-kilns, cement-works, etc. (6.) In mines, after explosions of “fire-damp.” These explosions are caused by the sudden union of the C and H of CH, with the O of the air, and are consequently attended by the formation of large volumes of C02, known to miners as after-damp. Constancy of the amount of atmospheric carbon dioxide.—It has been roughly estimated by Poggendorff that 2,500,000,000,000 cubic metres of C02 are annually discharged into our atmosphere, and that this quantity represents one eiglity-sixth of the total amount at present existing therein. This being the case, with the present production, the percentage of atmos- pheric C02 would be doubled in eighty-six years; no such increase has, however, been observed, and the average percentage found by Angus Smith, in 1872, is about the same as that observed by Boussingault in 1840, i.e., four parts in ten thousand. The C02 discharged into the air is, therefor, removed from it about as fast as it is produced. This removal is effected in two ways : (1) by the formation of deposits of earthy carbonates by animal organisms, corals, mollusks, etc.; (2) principally by the process of nutrition of vegetables, which absorb C02 both by their roots and leaves, and in the latter, under the influence of the sun’s rays, decompose it, retaining the C, which passes into more complex molecules ; and dis- charging a volume of O about equal to that of the C02 absorbed. Air contaminated with excess of carbon dioxide, and its effects upon the organism.—When, from any of the above sources, the air of a given locality has received sufficient CO„ to raise the proportion above 7 in 10,000 by volume, it is to be considered as contaminated ; the seriousness of the contamination depending not only upon the amount of the increase, but also upon the source of the CO„. If the gas be derived from fermen- tation, or from tellural or manufacturing sources, it is simply added to the otherwise unaltered air, and the absolute amount of oxygen present remains the same ; when, however, it is produced in a confined space by the processes of combustion and respiration, the composition of the air is much more seriously modified, as not only is there addition of a de- leterious gas, but a simultaneous removal of an equal volume of O ; hence the importance of providing, by suitable ventilation, for the supply of new air from without to habitations and other places where human beings are collected within doors, especially where the illumination is artificial. Although an adult man deoxidizes a little over 100 litres of air in an hour, a calculation of the quantity which he would require in a given time OXIDES OF CARBON. cannot be based exclusively upon that quantity, as the deoxidation cannot be carried to completeness ; indeed, wffien the proportion of in air ex- ceeds five per cent., it becomes incapable of supporting life, while a much smaller quantity, one per cent., is provocative of severe discomfort, to say the least. In calculating the quantity of air which should be supplied to a given enclosed space, most authors have agreed to adopt as a basis that the per- centage of CO,, should not be allowed to exceed 0.6 volume per 1,000 ; cf which 0.4 is normally present in air, and 0.2 the product of respiration or combustion. Taking the amount of C03 eliminated by an adult at 19 litres ( = 0.7 cubic foot) per hour, a man will have brought the air of an air-tight space of 100 cubic metres ( = 3,500 cubic feet) up to the permis- sible maximum of impurity in an hour. The following table is given by Parkes to indicate the contamination of air by the respiration of an adult in an hour, and the supply of external air required to restore the proper equilibrium : Amount of cubic space (breathing-space)for one man in cubic feet. Ratio per 1,000 of COa from respiration at the end of one hour, if there have been no change of air. Amount of air neces- sary to dilute to standard of 0.2, or in- cluding initial CO„, of 0.6 per 1,000 vol- umes during the first hour. Amount necessary to dilute to the given standard every hour after the first. 100 6.00 2,900 3,000 200 3.00 2,800 3,000 300 2.00 2,700 3,000 400 1.50 2,600 3,000 500 1.20 2.500 3,000 600 1.00 2,400 3,000 700 0.85 2,300 3,000 800 0.75 2,200 3,000 * 900 0.66 2,100 3,000 1,000 0.60 2,000 3,000 Practically, owing to the imperfect closing of doors and windows, and to ventilation by chimneys, inhabited spaces are never hermetically closed, and a less quantity of air-supply than that indicated in the table may usually be considered as sufficient. A sleeping-room occupied by a single person should have a cubic space of 30 to 50 cubic metres ( = 1,050 to 1,800 cubic feet), conditions which are fulfilled in rooms measuring 10 x 13 x 8 feet, and 13 x 15.6 x 9 feet. In calculating the space of dormitories to be occupied by several healthy people, the smallest air-space that should, under any circum- stances, be allowed, is 12 cubic metres (=420 cubic feet) for each person, To determine the number of individuals that may sleep in a room, multi- ply its length, width, and height together, and divide the product by 420 if the measurement be in feet, or by 12 if it be in metres. Thus, a dor- mitory 40 feet long, 20 feet wide, and 10 feet high, is fitted for the ac- commodation of 19 persons at most; for 40 x 20 x 10 = 8,000 and 8j°^Q = 19.05. As a rule, in places where many persons are congregated, it is neces- sary to resort to some scheme of ventilation by which a sufficient supply 240 MANUAL OF CHEMISTRY. of fresh air shall be introduced and the vitiated air removed, the quantity to be supplied varying according to circumstances. Experiment has shown that, in order to keep the air pure to the senses, the quantity of ail which must be supplied per head and per hour in temperate climates are as shown in the table : Situation. Cubic metres. Cubic feet. Situation. Cubic metres. Cubic feet. Barracks (daytime) 35 1,236 Hospital wards (surgical) 1T0 6,004 Barracks (night-time) TO 2.4T2 Contagious and lying-in.. 1T0 6,004 5.29T Workshops (mechanical) TO 2.4T2 Mines, metalliferous 150 School-rooms Hospital wards 35 85 1,236 3,002 Mines, coal 1T0 6,004 The amounts given are the smallest permissible, and should be ex- ceeded wherever practicable. Lights.—The amount of air to be supplied to each individual, given in the last section, are, with the exception of those furnished in mines, based upon the supposition that coal-gas is not used as a means of artificial il- lumination, or that the burners are so arranged with reference to the ventilating-flues that the products of combustion pass out immediately. Each cubic foot of illuminating-gas consumes in its combustion a quan- tity of O equal to that contained in 7.14 cubic feet of air, and produces 0.8 cubic feet of CO,, besides a large quantity of watery vapor, and less amounts of H„S04, SO„, and sometimes CO ; and an ordinary gas-burner consumes about three feet per hour. It is obvious, therefor, that a much larger quantity of pure air must be furnished to maintain the atmosphere of an apartment at the standard cf 0.6 per 1,000 of C02, when the vitia- tion is produced by the combustion of gas, than when it is the result of the respiration of a human being, and that to such an extent that a single tliree-foot burner requires a supply of air which would be sufficient for six human beings. As a basis for computation, it may be considered that, for each cubic foot of gas consumed, 1,800 cubic feet of air should be furnished by ventilation. The contamination of air by gas-lights becomes a question of serious importance in our dwellings upon occasions of social gatherings, and in theatres and other places of public resort which are used during the hours of darkness. The average size of a parlor in a city dwelling is 15 x 25 x 15 feet ; it therefor contains 4,875 cubic feet, and its atmosphere would, if it were hermetically closed, be brought to the standard of maximum allow- able contamination by the respiration of four adults in an hour, allowing 1,200 cubic feet per head, per hour. If such an apartment be illuminated, upon the occasion of an evening party at which fifty adults are present for four hours, by ten tliree-feet gas-burners, the amounts of air which should be supplied by ventilation are as follows in cubic feet: It the products of combus- tion of gas be discharged into the room. If the products of combus- tion of the gas be carried off. Per hour. Forfour hours. Per hour. For four hoars. 60.000 54.000 240,000 216.000 60,000 240,000 For ten gas-burners Totals 114,000 456,000 60,000 240,000 OXIDES OF CAKBON. 241 In tlie first instance, in which the products of the combustion of gas are discharged into the apartment, an adequate ventilation can only be secured by a complete change of the air every 2.6 minutes, which can only be attained by the use of mechanical contrivances, and with the production of draughts ; in the second instance, in which it is presumed that the gas-burners are so situated, -with reference to a ventilating shaft or shafts, that the products of combustion are immediately carried off, not only is the period in which a complete change of air is required ex- tended to 4.8 minutes, but the heat of the burners, causing an uptake current in the ventilator, favors the exit of the vitiated air, and the con- sequent entrance of external air to take its place. In theatres the contamination of the air by the burning of gas should be entirely eliminated by placing the burners either under the dome ven- tilator, or in boxes which open to the air of the house only below the level of the burner, and which are in communication with a ventilating- shaft. Even under these conditions it is necessary, to ensure perfect ventilation, to resort to some mechanical contrivance to remove the air vitiated by respiration and to supply its place by fresh air from without, which may be previously warmed or cooled according to the season, and which, in cities, should be filtered. When artificial illumination is obtained from lamps or candles, or from gas in small quantity and for a short time, the contamination of the air is sufficiently compensated by the ventilation through imperfect closing of the windows. A room without a window should never be used for human habitation. One important advantage of the electric light, if it ever become prac- ticable, will be that it consumes no O and produces no C02. Although, by the combustion of fuel, O is consumed and CO, pro- duced, heating arrangements only become a source of vitiation of air under the circumstances detailed above (see p. 234) ; indeed, in the majority of cases, if properly arranged, they are the means of ventilation, either by aspirating the vitiated air of the apartment, or by the introduction of air from without. Action on the economy.—An animal introduced into an atmosphere of pure C02 dies almost instantly, and without entrance of the gas into the lungs, death resulting from spasm of the glottis, and consequent apncea. When diluted with air, the action of C02 varies according to its pro- portion, and according to the proportion of O present. First.—When the proportion of O is not diminished, the poisonous action of C02 is not as manifest, in equal quantities, as when the air is poorer in oxygen. An animal will die rapidly in an atmosphere composed of 21 per cent. O, 59 per cent. N, and 20 per cent. C02 by volume ; but will live for several hours in an atmosphere whose composition is 40 per cent. O, 37 per cent. N, 23 per cent. C02. If C0.2 be added to normal air, of course the relative quantity of O is slightly diminished, while its absolute quantity remains the same; this is the condition of affairs existing in nature when the gas is discharged into the air ; under these circumstances an addition of 10-15 per cent, of CO, renders an air rapidly poisonous, and one of 5-8 per cent, will cause the death of small animals more slowly. Even a less proportion than this may become fatal to an individual not habituated. In the higher states of dilution, C0.2 produces immediate loss of mus cular power, and death without a struggle ; when more dilute, a sense o\ irritation of the larynx, drowsiness, pain in the head, giddiness, gradual loss of muscular power, and death in coma. 242 MANUAL OF CHEMISTRY. Second.—If the C02 present in air be produced by respiration or com- bustion, the proportion of O is at the same time diminished, and much smaller absolute and relative amounts of the poisonous gas will produce the effects mentioned above ; thus, an atmosphere containing in volumes 19.75 per cent. O, 74.25 per cent. N, 6 per cent. C02, is much more rapidly fatal than one composed of 21 per cent. O, 59 per cent. N, 20 per cent. CO,. With a corresponding reduction of O, 5 per cent, of C0o ren- ders an air sufficiently poisonous to destroy life ; 2 per cent, produces severe suffering; 1 per cent, causes great discomfort, while 0.1 per cent., or even less, is recognized by a sense of closeness. The treatment in all cases of poisoning by CO„ consists in the inhalation of pui’e air (to which a small excess of O may be added), aided, if neces- sary, by artificial respiration, the cold douche, galvanism, and friction. When it chances that an individual entering an atmosphere containing an excess of CO„, or other noxious gas, is seen to fall insensible, it is simply multiplying the number of victims, for others to follow, unpro- tected, with a view to effecting a rescue. Probably the most readily ob- tainable protection is a towel saturated with lime-water, and so held over the mouth and nostrils that the inspired air passes through it, and also through two or three layers of dry towelling interposed between the moist- ened part and the skin. Detection of carbon dioxide and analysis of confined air.—Carbon dioxide, or air containing it, causes a white precipitate when caused to bubble through lime or baryta water; normal air contains enough of the gas to form a scum upon the surface of these solutions when exposed to it. It was at one time supposed that air in which a candle continued to burn was also capable of maintaining respiration. This is, however, by no means necessarily true; a candle introduced into an atmosphere in which the normal proportion of O is contained, burns readily in the presence of 8 per cent, of C02; is perceptibly dulled by 10 per cent.; is usually extin- guished with 13 per cent.; always extinguished with 16 per cent. Its ex- tinction is caused by a less proportion of CO,, 4 per cent., if the quantity of O be at the same time diminished. Moreover, a contaminated atmos- phere may not contain enough C02 to extinguish, or perceptibly dim the flame of a candle, and at the same time contain enough of the monoxide to render it fatally poisonous if inhaled. The presence of CO, in a gaseous mixture is determined by its absorp- tion by a solution of potash ; its quantity either by measuring the diminu- tion in bulk of the gas or by noting the increase in weight of an alkaline solution. To determine the proportions of the various gases present in air the apparatus shown in Fig. 36 is used. A is an aspirator of known capacity, filled -with water at the beginning of the operation. It connects by a flexible tube from its upper part with an absorbing apparatus con- sisting of a, a U-shaped tube containing fragments of pumice stone, moist- ened with H2S04; by the increase in weight of this tube the weight of watery vapor in the volume of air drawn through by the aspirator is de- termined ; b, a Liebig’s bulb filled with a solution of potash ; c, a U-tube filled with fragments of pumice moistened with H,S04; b and c are weighed together and tlxeir increase in weight is the weight of C02 in the volume of air operated on. Every gram of increase in weight represents 0.50607 litre, or 31.60356 cubic inches ; d is a tube of difficultly fusible glass, filled with black oxide of copper and heated to redness ; e is a U-tube filled with pumice moistened with H2S04; its increase in weight represents H,0 obtained from decomposition of CH4. Every gram of increase in weight of 243 OXIDES OF CAKBON. e represents 0.444 gram, or 0.G21 litre, or 38.781 cubic inches of marsh gas ; f and g are similar to b and c, and their increase in weight represents CO, formed by oxidation of CO and CH( in d. From this the amount of CO is thus calculated : First, 2.75 grams are deducted from the increase of weight of / and g for each gram of CH( formed bv e ; of the remainder, every gram represents 0.6364 gram, or 0.5085 litre, or 31.755 cubic inches of CO. The air is drawn through the apparatus by opening the stopcock of A to such an extent that about 30 bubbles a minute pass through b. Fig. 36. Carbon disulphide—Bisulphide of carbon—Carbonei bisulphidum (U- &)— CS—76 —is formed by passing vapor of S over C heated to redness, and is partly purified by rectification. It is a colorless liquid; when pure it has a peculiar, but not disagree- able odor, the nauseating odor of the commercial product being due to the presence of another sulphurated body; boils at 47° (116°.6 F.) ; sp. gr. 1.293; very volatile; its rapid evaporation in vacuo produces a cold of — GO0 ( —76° F.); it does not mix with H,0 ; it refracts light strongly. It is highly inflammable, and burns with a bluish flame, giving oft' CO, and SO, ; its vapor forms highly explosive mixtures with air, which deto- nate on contact with a glass rod heated to 250° (482° F.). Its vapor forms a mixture with nitrogen dioxide, which, when ignited, burns with a bril- liant flame, rich in actinic rays. There also exists a substance intermediate in composition between CO, and CS4, known as carbon oxysidphide, CSO, which is an inflammable, col- orless gas, obtained by decomposing potassium sulphocyanate with dilute H„S04. Toxicology.—Cases of acute poisoning by CS2 have hitherto only been observed in animals ; its action is very similar to that of chloroform. Workmen engaged in the manufacture of CS, and in the vulcanization of rubber, as well as others exposed to the vapor of the disulphide, are sub- ject to a form of chronic poisoning which may be divided into two stages. The first, or stage of excitation, is marked by headache, vertigo, a dis- agreeable taste, cramps in the legs ; the patient talks, laughs, sings, and weeps immoderately, and sometimes becomes violently delirious. In the 244 MANUAL OF CHEMISTRY second stage the patient becomes sad and sleepy, sensibility diminishes, sometimes to the extent of complete anaesthesia, especially of the lower extremities, the headache becomes more intense, the appetite is greatly impaired, and there is general weakness of the limbs, which terminates in paralysis. The only remedy which has been suggested is thorough ventilation of the workshops, and abandonment of the trade at the first appearance of the symptoms. ch2oh Glycollic acid— | —76—is formed by the oxidation of glycol, by COOH the action of nitrous acid on glycocol, and by the action of potash on mono- cliloracetic acid. It forms deliquescent, acicular crystals ; very soluble in water ; soluble in alcohol and ether ; has a strongly acid taste and reaction ; fuses at 783 (172°.4F.); is decomposed at 150° (302° F.) ; at an intermediate tem- perature it loses H20, forming glycollide, or glycollic anhydride, C.,H.,02. Lactic acids—C3H603—90.—There are probably three, certainly two acids having this composition. Two of these would seem, from their pro- ducts of decomposition, to be of similar constitution, while the molecular composition of the third is distinct; the two of similar constitution are sometimes designated as ethylidene lactic acids, because of their containing the group of atoms CHa, while the third is designated as ethyleno-laetic acid, as it contains the group CH2 ; the constitution is expressed by the formulae : ch3 I CH,OH COOH ch2oh I ch2 I COOH Ethylidene lactic acid. Ethyleno-laetic acid. Obviously it is the ethylene acid which is the superior homologue of gly- collic acid. Ethyleno-lactic Acid.—Muscular tissue contains a mixture of this and optically active ethylidene lactic acid, which has been known as sarcolactic acid. Ethyleno-lactic acid may be obtained from muscular tissue or from Liebig’s extract of meat. It is optically inactive, as are also solutions of its salts ; its zinc salt contains 2 Aq, and is very soluble in water and quite soluble in alcohol. When oxidized by chromic acid it yields malonic acid. Of the two ethylidene lactic acids, that which is optically active is the one accompanying ethylene lactic acid, and predominating over it in amount, in dead muscle ; it is to this acid that the name par atactic acid is most properly applied. It may be obtained from Liebig’s meat extract. Paralactic acid differs from its two isomeres in that its solutions are dextrogyrous, and the solutions of its salts are kevogyrous. The specific rotary power of the acid is [«]„= -+-3°.5; that of the zinc salt [o]D= — 7.63; and of the calcium salt [a]D= —3°. 8. Its products of decomposi- tion are the same as those of ordinary lactic acid. Ordinary Lactic Acid—Lactic acid of fermentation—Optically inactive ethylidene lactic acid—Acidum lacticum (U. S.)—exists in nature, widely distributed in the vegetable kingdom, and as the product of a fermenta- OXIDES OF CARBON. 245 tion which is designated as the lactic, in milk, sour-krout, fermented beet- juice, and rice, and in the liquid refuse of starch factories and tanneries. Lactic acid is obtained as a product of the fermentation of certain sugars, milk-sugar and grape-sugar; as a result of the processes of nutri- tion of a minute vegetable, the lactic ferment, in which the sugar is con- verted into its polymere: C„HiaO# = It is usually produced by allowing a mixture of cane-sugar, tartaric acid, water, rotten cheese, skim milk and chalk to ferment for 10 days at 35° (95° F.). The calcium lactate produced is separated, purified and decomposed with an equivalent quantity of H.,S04. It has also been obtained synthetically by oxidation of the propylglycol of Wurtz, which is a secondary glycol, a synthesis which indicates its con- stitution : ch3 ch3 I I CHOH + 03 = CHOH + HO I' I CH.OH COOH Propylglycol. Oxygen. Lactic acid Water. It is a colorless, svropy liquid ; sp. gr. 1.215 at 20° (68° F.); does not solidify at —24° ( —11°.2 F.); soluble in water, alcohol, and ether ; is not capable of distillation without decomposition; wdien heated to 130° (266° F.) it loses water and is converted into dilactic acid, C(H1(,0., and, when heated to 250° (482° F.), into lactide, C3H1Oi. It is a good solvent of tricalcic phosphate. Oxidizing agents convert this acid into formic and acetic acids, without the formation of any malonic acid. Physiological.—The three lactic acids occur in animal nature, either free or in combination. Free lactic acid of fermentation occurs in the contents of the small intestine, and, when vegetable food has been taken, in the stomach; it is not, however, the acid to which the normal, unmixed gastric juice owes its acidity. Its salts have been found to exist in the contents of the stomach and those of the intestines, chyle, bile, parenchymatous fluid of spleen, liver, thymus, thyroid, pancreas, lungs, and brain ; urine. Pathologically in the blood in leucocythsemia, pyae- mia, puerperal fever, and after excessive muscular effort; in the fluids of ovarian cysts and transudations. In the urine it is abundant in phos- phorus-poisoning, in acute atrophy of the liver, and in rachitis and osteo malacliia. Muscular tissue, after death or continued contractions, contains the mixture of acids known to the older authors as sarcolactic acid. Normal, quiescent muscle is neutral in reaction ; but, when rigor mortis appears, or if the muscle be tetanized, its reaction becomes acid from the liberation of sarcolactic acid. Whether these acids are formed de novo during the contraction of the muscle, or whether they are produced by the decom- position of lactates existing in the quiescent muscle, is still undetermined; certain it is, however, that a given quantity of muscle has, when separated from the circulation, a fixed maximum of acid-producing capacity, which is greater in a muscle that has been tetanized during the interval between its removal and the establishment of rigor, than in one which has been at rest. There exist no grounds upon which to base the supposition that, in rheumatic fever, lactic acid is present in the blood. MANUAL OF CHEMISTRY. DIATOMIC AND DIBASIC ACIDS. Series CkH2„_204. Oxalic acid C2041I2 Malonic acid C304H4 ! Succinic acid C4O4H0 Ueoxyglutanic acid C304H8 j Adipic acid C604Hltf Pimelic acid C704H12 Suberic acid C804H14 Azelaic acid C904H1S Sebacic acid C,0O4Hlg Roccellic acid C]704Ha2 They are derived from the primary glycols by complete oxidation ; they are diatomic and dibasic, and contain two groups, CO, OH. They form two series of salts with the univalent metals, and two series of ethers, one of which contains neutral, and the other acid ethers. They may be obtained from the corresponding glycols, or from acids of the pre- ceding series, by oxidation. COOH Oxalic acid— | —90—C204Ha,2Aq—126—does not occur free COOH in nature, but in the oxalates of K, Na, Ca, Mg, and Fe in the juices of many plants, sorrel, rhubarb, cinchona, oak, etc.; as a native ferrous oxa- late ; and in small quantity in human urine. It is prepared artificially by oxidizing sugar or starch by HNOs, or by the action of an alkaline hydrate in fusion upon sawTdust. The soluble alkaline oxalate obtained by the latter method is converted into the insoluble Ca or Pb salt, which is washed and decomposed by an equivalent quantity of H2S04 or H2S ; and the liberated acid purified by recrystallization. Oxalic acid is also formed by the oxidation of many organic substances —alcohol, glycol, sugar, etc.; by the action of potassa in fusion upon the alkaline formiates ; and by the action of K or Na upon CO,,. It crystallizes in transparent prisms, containing 2Aq, which effloresce on exposure to air, and lose their Aq slowly but completely at 100° (212° F.), or in a dry vacuum. It fuses at 98° (208°.4 F.) in its Aq ; at 110°- 132° (230°-269°.6 F.) it sublimes in the anhydrous form, while a portion is decomposed ; above 160° (320° F.) the decomposition is more extensive ; H ,0, C02, CO, and formic acid are produced, while a portion of the acid is sublimed unchanged. It dissolves in 15.5 parts of water at 10° (50° F.); the presence of HN03 increases its solubility. It is quite soluble in alcohol. It has a sharp taste and an acid reaction in solution. Oxalic acid is readily oxidized ; in watery solution it is converted into C02 and H O, slowly by simple exposure to air, more rapidly in the pres- ence of platinum black or of the salts of platinum and gold ; under the influence of sunlight; or when heated with IIN03, manganese dioxide, chromic acid, Br, Cl, or livpochlorous acid. Its oxidation, when it is triturated dry with pure oxide of lead, is sufficiently active to heat the mass to redness. H..SO,, H P04, and other dehydrating agents decom- pose it into H„0, CO, and C02. Analytical Characters.—(1.) In neutral or alkaline solution a white ppt. with a solution of a Ca salt. (2.) Silver nitrate, a white ppt., soluble in HN03 and in NH4HO. The ppt. does not darken when the fluid is boiled, but, when dried and heated on platinum foil, it explodes. (3.) Lead acetate, in solutions not too dilute, a white ppt., soluble in HNOg, insoluble in acetic acid. DIATOMIC AND DIBASIC ACIDS. 247 Toxicology.—Although certain oxalates are constant constituents of vegetable food and of the human body, the acid itself, as well as hydro- potassic oxalate, is a violent poison when taken internally, acting both locally as a corrosive upon the tissues with which it comes in contact, and as a true poison, the predominance of either action depending upon the concentration of the solution. Dilute solutions may produce death without pain or vomiting, and after symptoms resembling those of narcotic poisoning. Death has followed a dose of 3 j. of the solid acid, and re- covery a dose of 3 j. in solution. When death occurs, it may be almost instantaneously, usually within half an hour ; sometimes after weeks or months, from secondary causes. The treatment, which must be as expeditious as possible, consists in the administration, first, of lime or magnesia, or a salt of Ca or Mg sus- pended or dissolved in a small quantity of HO or mucilaginous fluid ; afterward, if vomiting have not occurred spontaneously, and if the symptoms of con-osion have not been severe, an emetic may be given. In the treatment of this form of poisoning several points of negative cau- tion are to be observed. As in all cases in which a corrosive has been taken internally, the use of the stomach-pump is to be avoided. The al- kaline carbonates are of no value in cases of oxalic acid poisoning, as the oxalates which they form are soluble, and almost as poisonous as the acid itself. The ingestion of water, or the administration of warm water as an emetic, is contraindicated when the poison has been taken in the solid form (or where doubt exists as to what form it was taken in), as they dis- solve, and thus favor the absorption of the poison. Analysis.—In fatal cases of poisoning by oxalic acid the contents of the stomach are sometimes strongly acid in reaction ; more usually, owing to the administration of antidotes, neutral, or even alkaline. In a sys- tematic analysis the poison is to be sought for in the residue of the por- tion examined for prussic acid and phosphorus ; or, if the examination for those substances be omitted, in the residue or final alkaline fluid of the process for alkaloids (see p. 332 et seq.). If oxalic acid alone is to be sought for, the contents of the stomach, or other substances if acid, are extracted with water, the liquid filtered, the filtrate evaporated, the residue extracted with alcohol, the alcoholic fluid evaporated, the residue redissolved in water (solution No. 1). The portion undissolved by al- cohol is extracted with alcohol acidulated with hydrochloric acid, the solution evaporated after filtration, the residue dissolved in water (so- lution No. 2). Solution No. 1 contains any oxalic acid which may have existed free in the substances examined ; No. 2 that which existed in the form of soluble oxalates. If lime or magnesia have been administered as an antidote, the substances must be boiled for an hour or two with potas- sium carbonate (not the hydrate), filtered, and the filtrate treated as above. In the solutions so obtained, oxalic acid is characterized by the tests given above. The urine is also to be examined microscopically for crystals of cal- cium oxalate. The stomach may contain small quantities of oxalates as normal constituents of certain foods. CH — COOH Malonic acid— | —104—is a product of oxidation of COOH ethyleno-lactic acid, and is identical with the nicotic acid of tobacco. It forms prismatic crystals, very soluble in H,0, alcohol, and ether ; which fuse at 140° (284° F.), and are decomposed at 150° (302° F.). 248 MANUAL OF CHEMISTRY. CH—COOH Succinic acid— | —118—exists in amber, coal, fossil wood, CH.— COOH and in small quantity in animal and vegetable tissues. Its presence has been detected in the normal urine after the use of fruits and of asparagus, in the parenchymatous fluids of the spleen, thyroid, and thymus, and in the fluids of hydrocele and of hydatid cysts. It is also formed in small quan- tity during alcoholic fermentation ; as a product of oxidation of many fats and fatty acids ; and by synthesis from ethylene cyanide. It may be obtained by dry distillation of amber, or, preferably, by the fermentation of malic acid. It crystallizes in large prisms or hexagonal plates, which are colorless, odorless, permanent in air, acid in taste, soluble in water, sparingly so in ether and in cold alcohol. It fuses at 180° (356° F.), and distils with par- tial decomposition at 235° (455° F.). It withstands the action of oxidiz- ing agents ; reducing agents convert it into the corresponding acid of the fatty series, butyric acid ; with Br it forms products of substitution ; H.iS04 is without action upon it; phosphoric anhydride removes and converts it into succinic anhydride, C4H403. COMPOUND ETHERS OF THE ACIDS OF THE SERIES C„H2„03 and C„H2n_204. The members of both of these series contain two atoms of H replace- able by alcoholic radicals. In those of the series CnH2n03 (with the exception of carbonic acid), being monobasic, although diatomatic, it is not immaterial which H is so replaced. If it be that of the group CH2OH, the resulting compound is a monobasic acid, in which the H of the group COOH may be replaced by another alcoholic radical to form a neutral ether of the new acid ; if, on the other hand, the H of the group COOH be first replaced, a neutral compound ether is formed. In the members of the series CHII.lM_20,, which are dibasic, the substitution of an alco- holic radical for the H of either group COOH produces a monobasic acid, in which the H of the other COOH may be replaced by another radical to form a neutral ether. The following formulae indicate the differences in the nature of these compounds : CH.OH I COOH CH.OCH. I COOH CH.OH I COOC2H5 CH,OC„H. I cooc.,h6 Glycolic acid. Ethylglycolic acid. Ethyl glycolate. Ethyl ethylglycolate. COOH i COOH COOC.H I COOH COOC H. I COOC2H6 Oxalic acid. Ethyloxalic acid. Ethyl oxalate. AMINES OF THE GLYCOLS, 249 ALDEHYDES AND ANHYDRIDES OF THE SERIES C,lH,„03 and In treating of the monoatomic compounds, it was stated that sub- stances existed corresponding to the fatty acids, known as aldehydes and anhydrides, the former differing from the acids in that they contained the group COH instead of COOH ; the latter being the oxides of the acid radicals. Similar compounds exist corresponding to the acids of these two series. The aldehydes corresponding to the series CnH2„08 contain the group COH in place of the group COOH, and as they also contain the group CH'.OH, they are possessed of the double function of primary alcohol and aldehyde. Those of the series ChH.,„_204 form two series ; in one of which only one of the groups COOH is deoxidized to COH ; in the other, both. Those of the first series, still containing a group COOH, are monobasic acids as well as aldehydes : CHOH I COOH CH3OH COH COOH I COOH COOH I COH COH I COH Glycolic acid. Glycolic aldehyde Oxalic acid. Glyoxalic acid. Glyoxol. While the anhydrides of the fatty series may be considered as derived from the acids by the subtraction of H20 from two molecules of the acid ; those of both the series of acids under consideration are derived from a single molecule of the acid by the subtraction of H ,0 : CH;, I COOH CH.OH I COOH CH—COOH I CH,—COOH Succinic acid. Acetic acid. Glycolic acid. ch—cox >° CH—CO7 CH x i > CO / CH,—C0V i ' > CH—CO/ Acetic anhydride. Glycolic anhydride. Succinic anhydride. AMINES OF THE GLYCOLS. Ethylenic Compound Ammonias. These substances are derived from a double molecule of NH3, or of ammonium hydrate, by the substitution of the diatomic radicals of the glycols (hydrocarbons of the series CnH,„) for an equivalent number of H atoms. They are distinguished from the corresponding compounds of the radicals of the monoatomic alcohols, the monamines, by the designation of diamines. When it is considered that in the formation of these substances double 250 MANUAL OF CHEMISTRY. H atoms can be replaced by diatomic radicals to form primary, secondary, and tertiary amines : H.) h:[ ' (W) H. N, ' H.) (W) (CSHJ" N, H, (c..,h 4n OT1' N,; (CA)" Double ammonia molecule. Ethylene amine. Primary. Diethylene amine. Secondary. Triethylene amine. Tertiary. that others exist in which two univalent radicals replace a bivalent rad- ical ; others, again, in which H atoms have been replaced by groups OH ; and finally, that similar compounds of P, As and Sb exist, it is not aston- ishing that the study of the vast number of substances, the possibility of whose existence is thus indicated, is still in its infancy. Some recently discovered alkaloids, produced during putrefaction (see Ptomaines, p. 343), are diamines ; and there is strong probability that fur- ther investigation will show some of the vegetable alkaloids, whose consti- tution is as yet unknown, to belong in this class. AMIDES OF THE ACIDS OF THE SERIES CraH2„03 and CnH2„_204. This class of substances, formed by the substitution of radicals of the acids for H atoms in NH3 molecules, contains some substances of the greatest medical interest. The radicals of the acids of the series CnH2„03, except carbonic acid, being univalent, form amides similar in com stitution to those of the acids of the series C„H2„02 (p. 208). In the case of the dibasic acids no less than three series of amides are known to exist; thus we have, corresponding to oxalic acid : CO. io7N H/ CO. I CO/ HaX COOH I co\ H—N H/ COOH I COOH Oximide. Secondary monamide. Oxamide. Primary diamide. Oxamic acid. Primary monamide. Oxalic acid Acid. In the first of these, two H atoms of a single NH3 molecule are re placed by the bivalent radical of the acid ; these are distinguished as imides. Those of the second seines are normally formed diamides. In the third series, the univalent remainder, left by the removal of OH from the acid, replaces an atom of H in one molecule of NH., and the resulting compound, still containing a group COOH, has the functions of a mono- basic acid. Amides of Carbonic Acid. (CO )"\ Carbimide— N-—43.—Although cyanic acid (q.v.) has frequently H/ . been regarded as the imide of carbonic acid, there are many reasons, 251 AMIDES OF CARBONIC ACID. drawn from the methods of formation and properties of cyanic acid, CN which lead us to assign to it the constitution | , rather than that given OH above, and to consider it as an isomere of the hitherto undiscovered carb- imide. (CO)" ) Carbamide—Urea— H, N,—60. H i Occurrence.—Urea does not occur in the vegetable world. It exists principally in the urine of the mammalia ; also in smaller quantity in the excrements of birds, fishes, and some reptiles ; in the mammalian blood, chyle, lymph, liver, spleen, lungs, brain, vitreous and aqueous humors, sa- liva, perspiration, bile, milk, amniotic and allantoic fluids, muscular tissue, and in serous fluids (see below). Formation.—(1.) As a product of the decomposition of uric acid, usually by oxidation : c5h4n4o3 + h2o + o = con„h4 + c4h2n3o4 Uric acid. Water, Oxygen. Urea. Alloxan. (2.) By the oxidation of oxamide. (3.) By the action of caustic potassa upon creatin : C.H9N303 + H20 = CON2H4 + C3H,NOa Creatin. Water Urea. Sarcosine. (4.) By the limited oxidation of albuminoid substances, by potassium permanganate, and during the processes of nutrition. (5.) By the action of carbon oxychloride on dry ammonia. (6.) By the action of ammonium hydrate on ethyl carbonate at 180° (356° F.). (7.) By heating ammonium carbonate in sealed tubes to 130° (266° F.). (8.) By the slow evaporation of an aqueous solution of hydrocyanic acid. (9.) By the molecular transformation of its isomeride, ammonium cyanate. CN (CO) ) i = hIn, o (NHJ H2 Ammonium cyanate. Urea. Preparation.—(1.) From the urine.—Fresli urine is evaporated to the consistency of a syrup over the water-batli; the residue is cooled and mixed with an equal volume of colorless HX03 of sp. gr. 1.42 ; the crystals are washed with a small quantity of cold H O, and dissolved in hot H20 ; the solution is decolorized, so far as possible, without boiling, with animal charcoal, filtered, and neutralized with potassium cai'bonate ; the liquid is then concentrated over the water-batli, and decanted from the crystals of potassium nitrate which separate ; then evaporated to dryness over the water-bath, and the residue extracted with strong, hot alcohol; the alco- holic solution, on evaporation, leaves the urea more or less colored by uri- nary pigment. 252 MANUAL OF CHEMISTRY. (2.) By synthesis.—Urea is more readily obtained in a state of purity from potassium cyanate. This is dissolved in cold H O, and dry ammo- nium sulphate is added to the solution. Potassium sulphate crystallizes out and is separated by decanting the liquid, which is then evaporated over the water-batli, fresh quantities of potassium sulphate crystallizing and being separated during the first part of the evaporation ; the dry resi- due is extracted with strong, hot alcohol ; this, on evaporation, leaves the urea, which, by a second crystallization from alcohol, is obtained pure. Properties.—Physical.—Urea crystallizes from its aqueous solution in long, flattened prisms, and by spontaneous evaporation of its alcoholic solution in quadratic prisms with octahedral ends. It is colorless and odorless ; has a cooling, bitterish taste, resembling that of saltpetre ; is neutral in reaction ; soluble in one part of H.,0 at 15° (59° F.), the solu- tion being attended with diminution of temperature ; soluble in five parts of cold alcohol (sp. gr. 0.816) and in one part of boiling alcohol; very sparingly soluble in ether. When its powder is mixed with that of cer- tain salts, such as sodium sulphate, the Aq. of the salt separates, and the mass becomes soft or even liquid. When pure it is not deliquescent, but is slightly liygrometric, and when it is to be weighed it should be dried at 100° (212° F.) and cooled in a dessicator. Fuses at 130° (266° F.). Chemical.—Heated a few degress above 130° (266c F.) urea boils, giving off ammonia and ammonium carbonate, and leaves a residue of ammelide, C6H,N903. When heated to 150°-170° (302°-338c F.), it is decomposed, leaving a mixture of ammelide, cyanuric acid, and biuret: 8CON2H4 = 2CO, 4- C6H9N9Os + 7NH3 + H,0 Urea. Carbon dioxide. Ammelide. Ammonia. Water. 3CON„H4 = C303N3H3 + 3NHS Urea. Cyanuric acid. Ammonia. 2CONaH4 = C2H6N3Os + NHS Urea. Biuret. Ammonia. If urea is maintained at 150°-170° (302°-338° F.) for some time, a dry, grayish mass remains, which consists principally of cyanuric acid. In this reaction, the volatile products contain urea, not that that substance is volatile, but because a portion of the cyanuric acid and ammonia unite to regenerate urea by the reverse action to that given above. Dilute aqueous solutions of urea are not decomposed by boiling ; but if the solution be concentrated, or the boiling prolonged for a long time, the urea is partially decomposed into C0o and NH. The same decompo- sition takes place more rapidly and completely when a solution of urea is heated under pressure to 140° (284° F.). A pure aqueous solution of urea is not altered by exposure to filtered air. If urine be allowed to stand, putrefactive changes take place under the influence of a peculiar, organized ferment, or of a diastase-like body which is a constituent of normal urine. Chlorine decomposes urea with production of CO„, N, and HC1. Solu- tions of the alkaline hypochlorites and hvpobromites effect a similar de- composition in the pr-esence of an excess of alkali, according to the equation: CON3H4 + 3NaC10 = CO, + 2H,0 + N, + 3NaCl Urea. Sodium hypochlorite. Carbon dioxide. Water. Nitrogen. Sodium chloride. AMIDES OF CARBONIC ACID. 253 Upon this decomposition are based the quantitative processes of Ivnop, Hiifner, Yvon, Davy, Leconte, etc. Nitrous acid, or HXOa charged with nitrous vapors, decomposes urea according to the equation : CON.,H4 + NO = CO., 4- N4 + 2HaO (1) Urea. Nitrogen trioxide. Carbon dioxide. Nitrogen. Water. or the equation : 2CONsH4 + N.,03 = C03(NH4)a + N4 + CO, (2) Urea. Nitrogen trioxide. Ammonium carbonate. Nitrogen. Carbon dioxide. If the mixture be made in the cold, of one molecule of nitrogen tri- oxide to two molecules of urea, the decomposition is that indicated by Equation 2. If, on the other hand, the trioxide be gradually added to the previously warmed urea solution in the same proportion, half the urea is decomposed while the remainder remains unaltered, and, upon the addi- tion of a further and sufficient quantity of the trioxide, all the urea is de- composed according to Equation 1. Upon this reaction are based the processes of Grehant, Boymond, Draper, etc. When heated with mineral acids or alkalies, urea is decomposed with formation of CO., and NH3; if the .decomposing agent be an acid, CO„ is given off, and an ammoniacal salt remains ; if an alkali, a carbonate of the alkaline metal remains, and NH3 is given off. Upon this decomposition are based the processes of Heintz and Bagskv, Bunsen, etc. Urea forms definite compounds, not only with acids, but also with cer- tain oxides and salts. Of the compounds which it forms with acids, the most important are those with nitric and oxalic acids. Urea nitrate—CON^H^HNO.,—is formed as a white, crystalline mass when a concentrated solution of urea is treated, in the cold, with HN03. It is much less soluble in H,0 than is urea, especially in the presence of an excess of HXOs. It decomposes the carbonates with liberation of urea. If a solution of urea nitrate be evaporated over the water-bath, it is de- composed, bubbles of gas being given off beyond a certain degree of concentration, and lai;ge crystals of urea, covered with smaller ones of urea nitrate, separate. Urea oxalate—2CON .H , H,C ,04—separates as a fine, crystalline powder from mixed aqueous solutions of urea and oxalic acid of sufficient con- centration. It is acid in taste and reaction, less soluble in cold H„0 than the nitrate, and less soluble in the presence of an excess of oxalic acid than in pure H.20. Its solution may be evaporated at the temperature of the water-bath without suffering decomposition. Of the compounds of urea with oxides, the most interesting are those with mercuric oxide, three in number : «. CON.2H1,2HgO is formed by gradually adding mercuric oxide to a solution of urea, heated to near its boiling-point; the filtered liquid, on standing twenty-four hours, deposits crystalline crusts of the above com- position. [3. CON„H4,3HgO is formed as a gelatinous precipitate when mercuric chloride solution is added to a solution of urea containing potassium hydrate. MANUAL OF CHEMISTRY. y. CON2H4,4HgO is formed as a white, amorphous precipitate when a dilute solution of mercuric nitrate is gradually added to a dilute alka- line solution of urea, and the excess of acid neutralized from time to time. A yellow tinge in the precipitate indicates the formation of mercuric subnitrate after the urea has been all precipitated (Liebig’s process). Of the compounds of urea with salts, that with sodium chloride is the only one of importance : C0N2H4,NaCl,H20.—It is obtained in prismatic crystals when solu- tions of equal molecules of urea and sodium chloride are evaporated to- gether. It is deliquescent and very soluble in water. Its solution, when mixed with solution of oxalic acid, only forms urea oxalate after long standing, or on evaporation. Physiology.—Urea is a constant constituent of normal mammalian blood and urine, and is the chief product of the oxidation of albuminoid substances which occur in the body ; the bulk of the N assimilated from the food ultimately making its exit from the body in the form of urea in the urine. The determinations of the amount of urea in the blood and fluids other than the urine are, owing to imperfections in the processes of analy- sis, not as accurate as could be desired, the error being generally a minus one. Some of the more prominent are given in the following table : Quantity of Urea in Parts per 1,000 in Animal Fluids other than Urine. Normal blood—dog Normal blood—human Normal blood—human Normal blood—human Normal blood—human placental Normal blood—human foetal Blood of dog before nephrotomy Blood of dog, three hours after nephrotomy Blood of dog, twenty-seven hours after nephrotomy Human blood in cholera Human blood in cholera Human blood in Bright’s Lymph—dog 0.94-0.53 Munk. 0.19 Milk 0.13 Picard. Saliva Picard. Picard. Fluid of ascites 0.15 Picard. Perspiration Funke. Perspiration Picard. The quantity of urea contained in human urine under various circum- stances of health and disease has been the subject of a great number of investigations, and a determination of the amount voided in a given case is frequently of great importance to the physician, as indicating the amount of disassimilation of nitrogenous material occurring in the body at the time. Under normal conditions, the quantity of urea voided in twenty-four hours is subject to considerable variations, as is shown in the subjoined table: AMIDES OF CARBONIC ACID. Amount of Urea in Human Urine—Normal. Parts per 1.000. Grams in total urine of 24 hours. Urine of sp. gr. 1009.2 .... 9.88 Millon. Urine of sp. gr. 1011.0 .... 11.39 Millon. Urine of sp. gr. 1019.0 .... 18.58 Boymond. Urine of sp. gr. 1020.0 25.80 . Millon. Urine of sp. gr. lo27.7 29.70 Millon. Urine of sp. gr. 1028.0 .... 27.08 Boymond. Urine of sp. gr 1029.0 Millon. Urine of adult male (average) 30.0 Berzelius. Urine of adult male (average) 28.052 Lecanu. Urine of adult male (average) 25-32 22-35 Neubauer. Urine of adult male (average) 32-43 Kerner. Urine of adult male (average) 23.3 35 Y ogel. Urine of adult male, animal food 51-92 Franque. Urine of adult male, mixed food 36-38 Franque. Urine of adult male, vegetable food 24-28 Franque. Urine of adult male, non-nitrogenized food . . . 16 Franque. Urine of old men, 84-80 years 8.11 Lecanu. Urine of adult female (average) 19.116 Lecanu. Urine of pregnant female 30-38 Quinquand. Urine of female, 24 hours after delivery 20-22 Quinquand. Urine of infant, first day 0.03-0.04 Quinquand. Urine of infant, fifth day Urine of infant, eighth day 0.12-0.15 Quinquand. 0.2 -0.28 Quinquand. Urine of infant, fifteenth day 0.3 -0.04 Quinquand. Urine of child four years old. 4.505 Lecanu. Urine of child eight vears old 13.471 Lecanu. Urine of boy eighteen months old 8-12 Harley. Urine of girl eighteen months old 6-9 Harley. The variations are produced by : (1.) Age.—In new-born children the elimination of urea is insig- nificant. By growing children the amount voided is absolutely less than that discharged by adults, but, relatively to their weight, considerably greater ; thus, Harley gives the following amounts of urea in grams for each pound of body-weight in twenty-four hours: boy, eighteen months, 0.4 ; girl, eighteen months, 0.35 ; man, twenty-seven years, 0.25 ; woman, twenty-seven years, 0.20. During adult life the mean elimination of urea remains stationary, unless modified by other causes than age. In old age the amount sinks to below the absolute quantity discharged by growing children (2.) Sex.—At all periods of life females eliminate less urea than males. The proportion given by Beigel differs slightly from that of Harley, viz. : one kilo of male, 0.35 grams urea in twenty-four hours ; one kilo of female, 0.25 grams. During pregnancy females discharge more urea than males ; very shortly after delivery the amount sinks to the normal, below which it passes during lactation. (3.) Food.—The quantity of urea eliminated is in direct proportion to the amount of N contained in the food. The ingestion of large quantities of watery drinks increases the amount, and a contrary effect is produced by tea, coffee, and alcohol. With insufficient food the excretion of urea is diminished, although not arrested, even in extreme starvation. (4.) Exercise.—The question whether the elimination of urea is in- creased during violent muscular exercise is one which has been the subject of many observations and of much discussion. An examination of the 256 MANUAL OF CHEMISTRY. various results shows that, while the excretion of urea is slightly greater during violent exercise than during periods of rest, that increase is so in- significant in comparison to the work done, and, in some instances, to the loss of body-weight, as to render the assumption that muscular fox-ce is the result of the oxidation of the niti’Ogenized constituents of muscle im- probable. (See Gamgee : “ Physiological Chemistry,” i., pp. 385-401, for a full review of the subject.) The percentage of urea in the urine of the same individual is not the same at different times of the day. The minimum hourly elimination is in the morning hours ; an increase begins immediately after the principal meal, and reaches its height in about six hours, when a diminution sets in and progresses to the time of the next meal. Gorup-Besanez gives a curve representing the hourly variations in the elimination of ui’ea, which, reduced to figures, gives the following : Hour. Urea in grams. Hour. Urea in grams. Hour. Urea in grams. 8-9 A.M 1.5 4- 5 p.m 2.G 12-1 A.M 1.9 9-10 A.M 1.5 5- 6 p.m 3.1 1-2 A. M 1.9 10-11 A.M 1.4 0- 7 p.m 2.8 2-3 A.M 1.9 11 A.M.-12 M 1.3 7- 8 p.m 2.5 3-4 A.M 1.8 12 M -l P.M 1.8 8- 9 p.m 2.3 4-5 A.M 1.6 1-2 P.M 1.9 9-10 p.m 2.0 5-6 A.M 1.6 2-3 p.m 2.1 10-11 P.M 2.0 6-7 A.M 1 6 3-4 p.m 2.3 11-12 P.M 2.3 7-8 A.M 1.5 The total of which, however, represents a quantity above the normal. The absolute amount of urea eliminated in twenty-four hours is in- creased by the exhibition of diuretics, alkalies, colcliicum, turpentine, rhubarb, alkaline silicates, and compounds of antimony, arsenic, and phos- phorus. It is diminished by digitalis, caffein, potassium iodide, and lead acetate ; not sensibly affected by quinine. Pathologically the quantity of urea voided may be either increased or diminished : an increase above the normal indicating an increased oxida- tion of nitrogenous material, or the retention of the urea formed within the body ; and a diminution a deficient oxidation of the same class of sub- stances, or, as is frequently the case, a diminution in the supply of nitro- gen to the body from loss of appetite or power of assimilation. In acute febrile diseases both the relative and absolute amounts of urea eliminated augments, with some oscillations, until the fever is at its height; there is, however, no constant relation between the amount of urea eliminated and the body temperature. During the period of defer- vescence, the amount of urea eliminated in twenty-four hours is diminished below the normal; during convalescence it again slowly increases. If the malady terminate in death the diminution of urea is continuous to the end. In intermittent fever the amount of urea discharged is increased on the day of the fever and diminished during the interval. In cholera, dur- ing the algid stage, the elimination of urea by the kidneys is almost com- pletely arrested, while the quantity in the blood is greatly increased. When the secretion of urine is again established, the excretion of urea is greatly increased (60-80 grams = 926-1235 grains a day), and the abundant perspiration is also rich in urea. In cardiac diseases, attended AMIDES OF CARBONIC ACID. with respiratory difficulty, but without albuminuria, the elimination of urea is diminished and that of uric acid increased. In nephritis, attended with albuminuria, the elimination of urea at first remains normal; later it diminishes, and the urea, accumulating in the blood, gives rise to uraemic poisoning. The quantity of urea in the urine is also diminished in all diseases attended with dropsical effusions ; but is increased when the dropsical fluid is reabsorbed. In true diabetes the amount of urea in till urine of twenty-four hours is greater than normal. In chronic diseases the elimination of urea is below the normal, owing to imperfect oxidation. Analytical Characters.—To detect the presence of urea in a fluid, it is mixed with three to four volumes of alcohol, and filtered after having stood several hours in the cold ; the filtrate is evaporated on the water- bath, and the residue extracted with strong alcohol; the filtered alcoholic fluid is evaporated, and the residue tested as follows : (1.) A small portion is heated in a dry test-tube to about 1G0° (320° F.), until the odor of ammonia is no longer observed ; the residue is treated with a few drops of caustic potassa so- lution and one drop of cupric sulphate solution. If urea be present, the biuret resulting from its decomposition by heat causes the solution of the cupric oxide with a reddish-violet color. (2.) A portion of the residue is dissolved in a drop or two of II20, and an equal quantity of colorless concentrated HX03 added ; if urea be present in sufficient quantity there appear white, shining, hexagonal or rhombic, crystal- line plates or six-sided prisms of urea nitrate. (3.) A portion dissolved in water, as in (2), is treated with a solution of oxalic acid ; rhom- bic plates of urea oxalate crystallize. Determination of Quantity of Urea in Urine.—It must not be forgotten that, in all quantitative determinations of constituents of the urine, the question to be solved is not how much of that constituent is contained in a giv- en quantity of urine, but how much of that sub- stance the patient is discharging in a given time, usually twenty-four hours. Quantitative determinations are, therefor, in most cases, barren of useful results, unless the quantity of urine passed by the patient in twenty-four hours is known ; and, in view of diurnal vari- ations in elimination, unless the urine ex- amined be a sample taken from the mired urine of twenty-four hours. The procesR giving the most accurate results is that of Bunsen, in which the urea is decomposed into C02 and N H3, the former of which is weighed as barium carbonate. Unfortunately, this process requires an expenditure of time and a degree of skill in manipula- tion, which render its application possible only in a well-appointed laboratory. A process which is described in most text-books upon urinary analysis, and which is much used by phy- sicians, is that of Liebig. As this method is one. however, which contains more sources of error than any other, and as it can only b made to yield approximately correct results by a very careful elimination, as far as possible, of those defects, it is not one which is adapted to the use of the physician. Probably the most satisfactory process in the hands of the practitioner is that of Hiifner, based upon the reaction, to which attention was first called by Knop, of the alkaline hypobromites upon urea (p. 188) ; using, however, Dietrich’s apparatus, or the more simple modification suggested by Rumpf. in place of that of Hiifner. The apparatus (Fig. 37) consists of a burette of 30-50 c.c. capacity, immersed in a tall Pig. 37. MANUAL OF CHEMISTRY. Table of the Weight of One 720 722 724 726 728 730 732 734 736 738 740 742 744 f 10” 1.1338 1.1370 1.1402 1.1434 1.1406 1.1498 1.1529 1.1561 1.1593 1.1625 1.1657 1.1089 1.1721 o 11“ 1.1288 1.1320 1.1352 1.1384 1.1415 1.1447 1.1479 1.1511 1.1542 1.1574 1.1606 1.1638 1.1670 c& 12“ 1.1237 1.1209 1.1301 1.1333 1.1364 1.1396 1.1428 1.1459 1.1491 1.1523 1.1554 1.1586 1.1618 ft 13" 1.1187 1.1219 1.1251 1.128211.1314 1.1345 1.1377 1.1409 1.1440 1.1472 1.1503 1.1535 1.1566 *C 14“ 1.1130 1.1168 1.1200 1.1231 1.1203 1.1294 1.1326 1 1357 1.1389 1.1420 1.1452 1.1483 1.1515 o 15“ 1.1085 1,1117 1.1149 1.1180 1.1211 1.1243 1.1274 1.1305 1.1337 07 GO 1.1399 1.1431 1.1462 10“ 1.1034 1.1000 1.1097 1.1128 1.1160 1.1191 1.1222 1.1253 1.1285 1.1316 1.1347 1.1378 1.1409 a 17“ 1.0983 1.1014 1.1045 1.1076 1.1107 1.1138 1.1170 1.1201 1.1232 1.1263 1.1294 1.1325 1.1356 o 18“ 1.0930 1.0901 1.0992 1.1023 1.1054 1.1085 1.1117 1.1148 1.1179 1.1209 1.1241 1.1272 1.1303 19“ 1.0877 1.0908 1.0939 1.0970 1.1001 1.1032 1.1063 1.1094 1.1125 1.1156 1.1187 1.1218 1.1248 CS 20“ 1.0825 1.0855 1.0886 1.0917 1.0948 1.0979 1.1009 1.1040 1.1071 1.1102 1.1133 1.1164 1.1194 o 21° 1.0771 1.0802 1.0832 1.0863 1.0894 1.0924 1.0955 1.0986 1.1017 1.1047 1.1078 1.1109 1.1139 f 22“ 1.0717 1.0747 1.0778 1.0808 1.0639 1.0870 1.0900 1.0931 1.0961 1.0992 1.1023 1.1053 1.1084 s 23“ 1.0002 1.0092 1.0723 1.0753 1.0784 1.0814 1.0845 1.0875 1.0906 1.0936 1.0967 1.0997 1.1028 24“ 1.0600 1.0630 1.0007 1.0097 1.0728 1 0758 1.0789 1.0819 1.0849 1.0880 1.0910 1.0940 1.0971 .25“ 1.0550 1.0580 1.0010 1.0641 1.0671 1.0701 1.0732 1.0762 1.0792 1.0823 1.0853 1.0883 1.0913 720 722 724 726 728 730 732 734 736 738 740 742 744 Barometric pressure in millimetres. glass cylinder filled with water, and supported in such a way as to admit of being raised or lowered at pleasure. The upper end of the burette communicates with the evolution bottle a, which has a capacity of 75 c.c., by means of a rubber tube. The reagent required is made as follows: 27 c.c. of a solution of caustic soda, made by dissolving 100 grams NaHO in 250 c.c. H20, are brought into a glass-stoppered bottle, 2.5 c.c. bromine are added, the mixture shaken, and diluted with water to 150 c.c. The caustic soda solution may be kept in a glass- stoppered bottle, whose stopper is well paraffined, but the mixture must be made up as required. To conduct a determination, about 20 c.c. of the hypobrdmite solution are placed in the bottle a ; 5 c.c. of the urine to be examined are placed in the short test-tube, which is then introduced into the position shown in the figure, care being had that no urine escapes. The cork with its fittings is then introduced, the pinch cock b opened, and closed again when the level of liquid in the burette is the same as that in the cylinder. The decomposing vessel q is then inclined so that the urine and hypobromite solution mix; the decomposition begins at once, and the evolved N passes into the burette, which is raised from time to time, so as to keep the external and internal levels of water about equal ; the C02 formed is retained by the soda solution. In about an hour (the decomposition is usually complete in fifteen minutes, but it is well to wait an hour) the height is so adjusted that the inner and outer levels of water are exaotly even, and the graduation is read, while the standing of the barometer and thermometer are. noted at the same time. In calculating the percentage of urea from the volume of N obtained, it is essential that a correction should be made for differences of temperature and pressure, without which the result frotn an ordinary sample of urine may be vitiated by an error of ten percent. If, however, the temperature and barometric pressure have been noted, the correction is readily made by the use of the preceding table, computed by Dietrich. In the square of the table in which the horizontal line of the observed temperature crosses the vertical line of the observed barometric pressure will be found the weight, in milligrams, of a c.c. of N; this, multi- plied by the observed volume of N, gives the weight of N produced by the decomposition of the urea con- tained in 5 c.c. urine. But as fiO parts urea yield 28 parts N, the weight of N, multiplied by 2.14, gives the weight of urea in milligrams in 5 c.c. urine. This quantity, multiplied by twice the amount of urine in 24 hours, and divided by 10,000, gives the amount of urea eliminated in 24 hours in grams. If the result be desired in grains the amount in grams is multiplied by 15.434. Example.-—5 c.c. urine decomposed ; barometer = 736 mm ; thermometer = 10° ; burette reading be- fore decomposition = 64.2: same after decomposition = 32.6 : c.c. N collected = 31.6. From the table 1 c.c. N. at 10° and 736 mm. BP. weighs 1.1693. The patient passes 1500 c.c. urine in 24 hours; 31.6 x 1.1593 = 36.6339= milligr. N in 5 c.c. urine. 36.6339 x 2.14 = 7S.3965 = milligr. urea in 5 c.c. urine. m3965 XJ5000 _ 2g B19 _ mg urea in 24 hours. 10.000 23.519 x 15.434 = 362.99 = grains urea in 24 hours. In using this process it is well to have the urea solution as near the strength of one per cent, as possible; therefor, if the urine be concentrated, it should be diluted. Even when carefully conducted, the process is not strictly accurate; creatinin and uric acid are also decomposed with liberation of N, thus causing a slight plus error ; on the other hand, a minus error is caused by the fact, that in the decomposition of urea by the hypobromite, the theoretical result is never obtained within about eight per cent, in urine. These errors may be rectified to a great extent by multiplying the result by 1.044. A process which does not yield as accurate resells as the preceding, but which is more easy of appli- cation, is that of Fowler, based upon the loss of sp. gr. of the urine after the decomposition of its urea by hypochlorite. To apply this method the sp. gr. of the urine is carefully determined, as well as that of the liq. sodse chlorinate (Squibb’s). One volume of the urine is then mixed with exactly seven volumes of the COMPOUND UREAS. 259 Cubic Centimetre of Nitrogen. 746 748 750 752 754 756 758 760 762 764 766 768 770 1.1753 1.1785 1.1817 1.1848 1.1880 1.1912 1.1944 1.1976 1.2008 1.2040 1 2072 1.2104 1.2136 10°' 1.1701 1.1733 1.1705 1.1717 1.1829 1.1800 1.1892 1.1924 1.1956 1.1988 1.2019 1.2051 1.2083 11° 1.1049 1.1681 1.1713 1.1744 1.1776 1.1808 1.1839 1.1871 1.1903 1.1934 1.1906 1.1998 1 2029 12® o 1.1598 1.1630 1.1061 1.1093 1.1724 1.1756 1.1787 1.1819 1.1851 1.1882 1.1914 1.1945 1.1977 13® 3 1.1540 1.1577 1.1609 1.1640 1.1672 1.1703 1.1735 1.1766 1.1798 1.1829 1.1861 1.1892 1.1923 14“ 1 1 1493 1.1525 1.1550 1.1587 1.1619 1.1050 1.1081 1.1713 1.1744 1.1775 1.1807 1.1838 1.1809 15“ 1.1441 1.1472 1.1503 1.1534 1.1560 1.1597 1.1028 1.1659 1.1691 1.1722 1.1753 1.1784 1.1816 16“ 1.1397 1.1419 1.1450 1.1481 1.1512 1.1543 1.1574 1.1005 1.1636 1.1667 1 1699 1.1730 1.1761 17“ O 1.1334 1.1305 1.1396 1.1427 1.1458 1.1489 1.1520 1.1551 1.1582 1.1613 1.1644 1.1675 1.1706 18" 3 1.1279 1.1310 1.1341 1.1372 1.1403 1.1434 1.1405 1.1496 1.1527 1.1558 1.1589 1.1620 1.1650 19“ o 1.1225 1.1256 1.1287 1.1318 1.1348 1.1379 1.1410 1.1441 1.1472 1.1502,1.1533 1.1504 1.1595 20“ s 1.1170 1,1201 1.1231 1.1202 1.1293 1.1324 1.1354 1.1385 1.1416 1.1446 1.1477 1.1508 1.1539 21“ c. 1.1115 1.1145 1.1170 1.1206 1.1237 1.1268 1.1298 1.1329 1.1359 1.1390 1.1421 1.1451 1.1482 22“ 3 1.1058 1.1089 1.1119 1.1150 1.1180 1.1211 1.1241 1.1272 1.1302 1.1833 1.1363 1.1894 1.1424 23“ 1.1001 1.1032 1.1062 1.1092 1.1123 1.1153 1 1184 1.1214 }.1244 1.1275 1.1305 1.1336 1.1366 24“ P 1.0944 1.0974 1.1004 1.1035 1.1065 1.1095 1.1126 1 1156 1.1186 1.1216 1 1247 1.1277 1.1307 25“ 746 748 750 752 754 756 758 760 762 764 766 768 770 Barometric pressure in millimetres. liq. sod. chlor., and, after the first violence of the reaction has subsided, the mixture is shaken from time to time during an hour, when the decomposition is complete ; the sp. gr. of the mixture is then determined. As the reaction begins instantaneously when the urine and reagent are mixed, the sp. gr. of the mixture must be calculated by adding together once the sp. gr. of the urine and seven times the sp. gr. of the liq. sod. chlor., and dividing the sum by eight. From the quotient so obtained the sp. gr. of the mixture after decomposition is subtracted : every degree of loss in sp. gr. indicates 0.771)1 gram of urea in 100 c.c. of urine. The sp. gr. determinations must all be made at the same temperature; and that of the mixture only when the evolution of gas has ceased entirely. Finally, when it is only desired to determine whether the urea is greatly in excess or much below the normal, advantage may be taken of the formation of crystals of urea nitrate. Two samples of the urine are taken, one of 5 c.c. and one of 10 c.c. ; the latter is evaporated, at a low temperature, to the bulk of the former, and cooled; to both one-tliird volume of colorless HN03 is added. If crystals do not form within a few moments in the concentrated sample, the quantity of urea is below the normal; if they do in the unconcentrated sample, it is in excess. In using this very rough method, regard must be had to the quantity of urine passed in 24 hours ; the above applies to the normal amount of 1200 c.c. ; if the quantity be greater or less, the urine must be concentrated or diluted in proportion. This method cannot be used if the urine is albuminous. Compound Ureas. These compounds, which are exceedingly numerous, may be considered as formed by the substitution of one or more alcoholic or acid radicals for one or more of the remaining H atoms of urea. Those containing alcoholic radicals may be obtained, as urea is ob- tained from ammonium cyanate, from the cyanate of the corresponding compound ammonium ; or by the action of NH3, or of the compound ammonias, upon the cyanic ethers. Those containing acid radicals have received the distinctive name of ureids ; some of them are derivatives of uric acid, which is itself probably MANUAL OF CIIEMISTKY. an ureitl. We will limit our consideration of these bodies to uric acid and the ureids obtained from and related to it. Uric acid—Lithic acid—C6H2N4OsHa—1G8.—Occurrence.—So far as yet known, uric acid is exclusively an animal product. It exists in the urine of man and of the carnivora, and in that of the lierbivora when, during early life or starvation, they are for the time being carnivora ; as a constituent of urinary calculi ; and very abundantly in the excrement of serpents, tortoises, birds, molluscs, and insects, also in guano. It is pres- ent in very small quantity in the blood of man, more abundantly in that of gouty patients and in that of birds. The so-called “chalk-stones” de- posited in the joints of gouty patients are composed of sodium urate. It also occurs in the spleen, lungs, liver, pancreas, brain, and muscular fluid. Preparation.—Although uric acid may be obtained from calculi, urine, and guano, the source from which it is most readily obtained in a state of purity is the solid urine of large serpents, which is composed almost entirely of uric acid and the acid urates of sodium, potassium, and am- monium. This is dried, powdered, and dissolved in a solution of potassium hydrate, containing one part of potash to 20 of water; the solution is boiled until all odor of NH3 has disappeared. Through the filtered solu- tion C0.2 is passed, through a wide tube, until the precipitate, which was at first gelatinous, has become granular and sinks to the bottom ; the acid potassium urate so formed is collected on a filter, and washed with cold H.,0 until the wasli-wrater becomes turbid when added to the first filtrate; the deposit is now dissolved in hot dilute caustic potassa solution, and the solution filtered hot into HC1, diluted with an equal volume of H20. The precipitated uric acid is washed and dried. Properties—Physical.—Uric acid, when pure, crystallizes in small, white, rhombic, rectangular or hexagonal plates, or in rectangular prisms, or in dendritic crystals of a hydrate, C:H4N403,2H20. As crystallized from urine it is more or less colored with urinary pigments, and forms rectangular or rhombic plates, usually with the angles rounded so as to form lozenges, which are arranged in bundles, daggers, crosses, or den- dritic groups, sometimes of considerable size. It is almost insoluble in H.,0, requiring for its solution 1900 parts of boiling H.,0 and 15,000 parts of cold H.,0 ; insoluble in alcohol and ether ; its aqueous solution is acid to test-paper ; cold HC1 dissolves it more readily than H ,0, and on evapo- ration deposits it in rectangular plates. It is tasteless and odorless. Chemical.—When heated, it is decomposed without fusion or sublima- tion. Its constitution is unknown. Heated in Cl it yields cyanuric acid and HC1. When Cl is passed for some time through H O holding uric acid in suspension, alloxan, parabanic and oxalic acids, and ammonium cyanate are formed. Similar decomposition is produced by Br and I. It is simply dissolved by HC1. It is dissolved by H2S04; from a hot solu- tion in which a deliquesceut, crystalline compound, CtH4N403, 4H.,S04 is deposited; it is partly decomposed by H2S04 at 140° (284° F.). It dis- solves in cold HN03 with effervescence and formation of alloxan, alloxan- tine, and urea ; with hot HX03 parabanic acid is produced. Solutions of the alkalies dissolve uric acid with formation of neutral urates. Uric acid is dibasic. Ammonium urates.—The neutral salt, C.H,N403(NII4)2, is unknown. The acid salt, C.H3N403(NH4), exists as a constituent of the urine of the lower animals, and occurs, accompanying other urates and free uric acid, in urinary sediments and calculi. Sediments of this salt are rust-vellow or pink in color, amorphous, or composed of globular masses, set with pro- COMPOUND UREAS. 261 jecting points, or elongated dumb-bells, and are formed in alkaline urine. It is very sparingly soluble in H20 ; soluble in warm HC1, from which solution crystalline plates of uric acid are deposited. Potassium urates.—The neutral salt, C5H ,N403K„ is obtained when a solution of potassium hydrate, free from carbonate, is saturated with uric acid ; the solution on concentration deposits the salt in line needles. It is soluble in 44 parts of cold H.,0 and in 35 parts of boiling H.,0. It is alkaline in taste, and absorbs CO., from the air. The acid salt, C6HsN403K, is formed as a granular (at first gelatinous) precipitate when a solution of the neutral salt is treated with C02. It dissolves in 800 parts of cold H.,0 and in 80 parts of boiling H.,0. The occurrence of potassium urates in urinary sediments and calculi is very exceptional. Sodium urates.—The neutral salt, C.H.,X4O Xa„, is formed under simi- lar conditions as the corresponding potassium salt. It forms nodular masses, soluble in 77 parts of cold H20 and in 75 of boiling H.,0; it absorbs COs from the air. The acid salt, C.H N4O Na, is formed when the neutral salt is treated with C02. It is soluble in 1200 parts of cold H O and in 125 parts of boiling 11,0. It occurs in urinary sediments and calculi, very rarely crys- tallized. The arthritic calculi of gouty patients are almost exclusively composed of this salt, frequently beautifully crystallized. Calcium urates.—The neutral salt, C.H2N403Ca, is obtained by drop- ping a solution of neutral potassium urate into a boiling solution of cal- cium chloride until the precipitate is no longer redissolved, and then boil- ing for an hour. A granular powder, soluble in 1500 parts of cold H.,0 and in 1440 parts of boiling H20. The acid salt, (CtH3N403)2Ca, is obtained by decomposing a boiling solution of acid potassium urate with calcium chloride solution. It crys- tallizes in needles, soluble in 603 parts of cold H.,0 and in 276 parts of boiling H,0. It occurs occasionally in urinary sediments and calculi, and in “chalk-stones.” Lithium urates.—The acid salt, C;.H3N403Li, is formed by dissolving uric acid in a warm solution of lithium carbonate. It crystallizes in needles, which dissolve in 60 parts of H.,0 at 50: (122° F.) and do not separate when the solution is cooled. It is with a view to the formation of this, the most soluble of the acid urates, that the compounds of lithium are given to patients suffering with the uric acid diathesis. Physiology.—Uric acid exists in the economy chiefly in combination as its sodium salts ; it is occasionally found free, and from the probable method of its formation it is difficult to understand how all the uric acid in the economy should not have existed there free, at least at the instant of its formation. It can scarcely be doubted that uric acid is one of the products of the oxidation of the albuminoid substances—an oxidation in- termediate in the production of urea ; and that consequently diseases in which there is an excessive formation of uric acid, such as gout, have their origin in defective oxidation. In human urine the quantity of uric acid varies with the nature of the food in the same manner as does urea, and in about the same pro- portion : Urea. Uric acid. Proportion of uric acid to urea. Animal food 71.5 1.25 57.2 Mixed food 0.70 48.7 Vegetable food 20.0 0.50 52.0 Non-nitrogenized food 10 0 0.34 47.0 262 MANUAL OF CHEMISTRY. The mean elimination of uric acid in the urine is from one-thirty-fifth to one-sixtieth of that of urea, or about 0.5 to 1.0 gram (7.7-15.4 grains) in 24 hours. With a strictly vegetable diet the elimination of 24 hours may fall to 0.3 gram (4.6 grains), and with a surfeit of animal food it may rise to 1.5 gram (23 grains). The hourly elimination is increased after meals, and diminished by fasting and by muscular and mental activity. Deposits of free uric acid occur in acid, concentrated urines. In gout the proportion of uric acid in the urine is diminished, although, owing to the small quantity of urine passed, it may be relatively great; during the paroxysms the quantity of uric acid is increased, both relatively and absolutely. The proportion of uric acid in the blood is invariably in- creased in gout. Analytical Characters.—Uric acid may be recognized by its crystalline form and by the murexid test. To apply this test the substance is moistened with HNOa, which is evaporated nearly to dryness at a low temperature ; the cooled residue is then moistened with ammonium hydrate. If uric acid be present, a yellow residue—sometimes pink or red when the uric acid was abundant—remains after the evaporation of the HNOs, and this, on the addition of the alkali, assumes a rich purplish-red color. To detect uric acid in the blood, about two drachms of the serum are placed in a flat glass dish and faintly acidulated with acetic acid ; a very fine fibril of linen thread is placed in the liquid, which is set aside and allowed to evaporate to the consistency of a jelly ; the fibril is then removed and examined microscopically. If the blood contain uric acid in abnormal proportion, the thread will have attached to it crystals of uric acid. Quantitative Determination.—The best method for the determination of the quantity of uric acid in urine is the following: 250 c.c. of the fil- tered urine are acidulated with 10 c.c. of HC1, and the mixture set aside for 24 hours in a cool place. A small filter is washed, first with dilute HC1 and then with H..O, dried at 100° (212° F.), and weighed. At the end of 24 hours this filter is moistened in a funnel, and the crystals of uric acid collected upon it (those which adhere to the walls of the precipitating vessel are best separated by a small section of rubber tubing passed over the end of a glass rod, and used as a brush). No H.20 is to be used in this part of the process, the filtered urine being passed through a second time, if this be required, to bring all the crystals upon the filter. The deposit on the filter is now -washed with 35 c.c. of pure H.,0, added in small portions at a time ; the filter and its contents are then dried and weighed. The difference between this weight and that of the dry filter alone is the weight of uric acid in 250 c.c. of urine. If from any cause more than 35 c.c of wash-water have been used, 0mgr-.043 must be added to this weight for every c.c. of extra wash-water. If the urine contain albumen, this must first be separated by adding two or three drops of acetic acid, heating to near 100° (212° F.), until the coagulum becomes flocculent, and filtering. Ureids derived from Uric Acid.—These substances are quite numer- ous, and are divisible into ureids, diureids, triureids, and uraemic acids, ac- cording as they are formed by substitution in one, two, or three molecules of urea, and according as the acid radical substituted does or does not re- tain a group COOH. Some of these substances require a brief mention : (CO)") Oxalylurea—Parabanic acid— AA)" N —114 —is urea in which H, ) two atoms of H have been replaced by the bivalent radical (C20„) , of 263 SUBSTANCES OF UNKNOWN CONSTITUTION. oxalic acid. It is obtained by oxidizing uric acid or alloxan by hot hno3. Allantoin—C4HeN4Oa—130—occurs in the allantoic fluid of the cow; in the urine of sucking calves, in that of dogs and cats when fed on meat, in that of children during the first eight days of life, in that of adults after the ingestion of tannin, and in that of pregnant women. It is pro- duced artificially by oxidizing uric acid, suspended in boiling H30, with lead dioxide. It crystallizes in small, tasteless, neutral, colorless prisms; sparingly soluble in cold H.,0, readily soluble in warm H30. Heated with alkalies it yields oxalic acid and NH3; and with dilute acids, allanturic acid, C.H.N.O,, Allantoin has been obtained synthetically by heating together gly- oxylic acid and urea. Mesoxalylurea—Alloxan—C4H.,N"sO.—142—is a product of the lim- ited oxidation of uric acid. It has been found in the intestinal mucus in a case of diarrhoea. It forms colorless crystals, readily soluble in H.,0. It gradually turns red in air, and stains the skin red. Oxaluric acid—C3HlN.,Ol—132—occurs in its ammonium salt, as a normal constituent, in small quantity, in human urine. It may be obtained by heating oxalylurea with calcium carbonate. It is a white, sparingly soluble powder, which is converted into urea and oxalic acid when boiled with water or alkalies. Its ammonium salt crystallizes in white, glistening, sparingly soluble needles. Its ready con- version into urea and oxalic acid and its formation from oxalylurea, itself a product of oxidation of uric acid, render it probable that oxaluric acid is one of the many intermediate products of the oxidation of the nitroge- nous constituents of the body. Dialuric acid—Oxybarbituric acid—C4H4NaO — a dibasic acid, pro- duced by reduction of alloxan. Alloxantine—C,H ,N 4 O 7—is a substance crystallizing in small, brill- iant, very sparingly soluble prisms, produced by the action of reducing agents upon alloxan, whose action is less powerful than that required to convert alloxan into dialuric acid. Murexide — Ammonium purpurate—C8H4(NH4)N6Ofl — is produced by oxidation of uric acid, of alloxan, and of a number of other derivatives of uric acid with subsequent contact of ammonium hydrate. It is sup- posed to be the ammonium salt of a hypothetical and non-isolated acid. The ammonium salt is of a brilliant, but evanescent purple color. (See Murexid test for uric acid, p. 262.) Hydurilic acid—C,HNtO —is produced as a yellowish, crystalline, sparingly soluble powder by heating together glycerin and dialuric acid. It is a strong dibasic acid. Violuric acid—C4H3N304—is produced, along with alloxan, by the action of nitric acid upon hydurilic acid. It forms small, readily soluble, octahedral crystals. It is a strong monobasic acid, whose salts are brill- iantly colored. 264 MANUAL OF CI1EMISTKY. TRIATOMIC ALCOHOLS. Series CmH2„+203. There is as yet only one alcohol known containing a trivalent radical. This is glycerin, whose relation to the monoatomic and diatomic alcohols is shown by the following formulae : ch3 I ch2 I CH3 CH, I ch2 I ch2oh * CH2OH ch2 ch„oh CHOH I CHOH I ch.2oh Glycerin—Glycerinum (V. S.)—C,Hr(OH)3—92—was first obtained as a secondary product in tlie manufacture of lead plaster ; it is now pro- duced as a by-product in the manufacture of soaps and of stearin candles. It exists free in palm-oil and in other vegetable oils ; it is produced in small quantity during alcoholic fermentation, and is consequently present in wine and beer. It is much more widely disseminated in its ethers, the neutral fats, in the animal and vegetable kingdoms. It has been obtained by partial synthesis, by heating for some time a mixture of allyl tribromide, silver acetate and acetic acid, and saponifying the triacetin so obtained. The glycerin obtained by the process now generally followed—the de- composition of the neutral fats and the distillation of the product in a cur- rent of superheated steam—is free from the impurities which contaminated the product of the older processes. The only impurity likely to be pres- ent is water, which may be recognized by the low sp. gr. Glycerin is a colorless, odorless, syrupy liquid, has a sweetish taste ; sp. gr. 1.2G at 15° (59a F.). Although it cannot usually be caused to crystallize by the application of the most intense cold, it does so some- times under imperfectly understood conditions, forming small, white needles of sp. gr. 1.2G8, and fusible between 7° and 8° (44°.G-46°.4F.). It is soluble in all proportions in water and alcohol, insoluble in ether and in chloroform. The sp. gr. of mixtures of glycerin and water increase with the proportion of glycerin. It is a good solvent for a number of min- eral and organic substances (glycerites and glyceroles). It is not volatile at ordinary temperatures. When heated, a portion distils unaltered at 275c-280° (527°-536° F.), but the greater part is decomposed into acrolein, acetic acid, carbon dioxide, and combustible gases. It may be distilled unchanged in a current of superheated steam between 285° and 315° (545°-599c F.). Concentrated glycerin, when heated to 150° (302° F.) ignites and burns without odor and without leaving a residue, and with a pale-blue flame. It may also be burnt from a short wick. Glycerin is readily oxidized, yielding different products with different degrees of oxidation. Platinum black oxidizes it, with formation, finally, of H.,0 and CO„; oxidized by manganese dioxide and H.,S04, it yields CO., and formic acid. If a layer of glycerin, diluted with an equal volume of H.,0 be floated on the surface of HNOs of sp. gr. 1.5, a mixture of several acids, is formed : oxalic, 2C.,04H.,; glyceric, CsHf04 ; formic, CH,0„ ; glycollic, C.,H40;i ; glyoxylic, C,H,04; and tartaric, C4H(,0„. When glycerin is heated with potassium hydrate, a mixture of potassium acetate and formiate is Propane. Propyl alcohol. Propyl glycol. Glycerin. ETHERS OF GLYCERIN. produced. When glycerin, diluted with 20 volumes of HO, is heated with Br ; COa, bromoform, glyceric acid, and HBr are produced. Phosphoric anhydride removes the elements of H O from glycerin, with formation of acrolein (see p. 224). A similar action is effected by heating with H„S04, or with potassium hydrosulphate. Heated with oxalic acid, glycerin yields CO„ and formic acid. The presence of glycerin in a liquid may be detected as follows: Add NaHO to feebly alkaline reaction, and dip into it a loop of Pt wire hold- ing a borax bead ; then heat the bead in the blow-pipe tiarne, which is col- ored green if the liquid contain of glycerin. The glycerin used for medicinal purposes should respond to the fol- lowing tests : (1) its sp. gr. should not vary much from that given above ; (2) it should not rotate polarized light; (3) it should not turn brown when heated with sodium hydrate ; (4) it should not be colored by H,S ; (5) when dissolved in its own weight of alcohol, containing one per cent, of HaS04, the solution should be clear; (6) when mixed with an equal volume H ,S04, of sp. gr. 1.83, it should form a limpid, brownish mixture, but should not give off gas. ACIDS DERIVABLE FROM THE GLYCERINS. Two series of acids are derivable from the glycerins by substitution of O for H, in the group CH,OH : CH„OH I CHOH I CH.,OH CHOH I CHOH I COOH COOH I CHOH I COOH Glycerin, Glyceric acid. Tartronic acid, The terms of both series are triatomic ; those of the glyceric series are monobasic, and those of the tartronic series are dibasic (see p. 231). Malic acid—C4He06—134—is the second term of the tartronic series, and is therefor dibasic. It exists in the vegetable kingdom ; either free or combined with K, Na, Ca, Mg, or organic bases ; principally in fruits, such as apples, cherries, etc. ; accompanied by citrates and tartrates. It crystallizes in brilliant, prismatic needles ; odorless ; acid in taste ; fusible at 100° (212° F.); loses H.,0 at 140° (284° F.) ; deliquescent ; very soluble in H„0 and in alcohol. Heated to 175°-180° (347c-356° F.), it is decomposed into H20 and maleic acid, C4H404. The malates are oxidized to carbonates in the body. ETHERS OF GLYCERIN, Glycerides. As glycerin is a triatomic alcohol, it contains three oxhydryl groups which may be removed, combining with H from an acid to form H. O, and leaving a univalent, bivalent, or trivalent remainder, which may replace the H of monobasic acids to form three series of ethers. As, further, the 266 MANUAL OF CHEMISTRY. OH groups differ from each other in that two of them are contained in the primary group CH..OH, the other in the secondary group CHOH, there exist two isomeres of each mono- and di-glyceride. cii2oh I CHOH I ch2oh ch2—o—c.h3o CHOH ! CH2OH CH—O—C,H30 I CH—O—C2H30 \ CH2OH CH—O—C,HaO I CH—O—C2H30 i CH— O—C2HaO Glycerin. Manoacetin. Diacetin. Triacetin. Of the many substances of this class, only a few, principally those en- tering into the composition of the neutral fats, require consideration here. Tributyrin—C3H5 (0,C 4H,0)3—302—exists in butter. It may also be obtained by heating glycerin with butyric acid and H,S04. It is a pungent liquid, very prone to decomposition, with liberation of butyric acid. Trivalerin—C.,Hr (0,C H O) 3—344—exists in the oil of some mari- time mammalia, and is identical with the phocenine of Chevreul. Tricaproin — C.H. (0,C6Hn0)3— 38G — Tricaprylin C H (0,CS H150>3 —470—and Trieaprin—C.,H5 (O,C40H](JO)3—554—exist in small quantities in milk, butter, and cocoa-butter. Tripalmitin—C,tH. (0,ClfH310)3—806—exists in most animal and vegetable fats, notably in palm-oil ; it may also be obtained by heating glycerin with 8 to 10 times its weight of palmitic acid for 8 hours at 250° (482° F.). It forms crystalline plates, very sparingly soluble in alcohol, even when boiling ; very soluble in ether. It fuses at 50° (122° F.) and solidifies again at 46° (114°. 8 F.). Trimargarin—-C3H. (0,G17H330)3- -848—has probably been obtained artificially as a crystalline solid, fusible at 60° (140° F.), solidifiable at 52° (125°.6 F.). The substance formerly described under this name as a con- stituent of animal fats is a mixture of tripalmitin and tristearin. Tristearin—C H:i (0,C,MH.J;0)3- -890—is the most abundant constit- uent of the solid fatty substances. It is prepared in large quantities as an industrial product in the manufacture of stearin candles, etc., but is ob- tained in a state of purity only with great difficulty. In as pure a form as readily obtainable, it forms a hard, brittle, crystal- line mass ; fusible at 68° (154°.4 F.), solidifiable at 61° (141°.8 F.) ; soluble in boiling alcohol, almost insoluble in cold alcohol, readily soluble in ether. Triolein—C.(Hr (0,Cl4H330)s —884—exists in varying quantity in all fats, and is the predominant constituent of those which are liquid at ordi- nary temperatures; it may be obtained from animal fats by boiling with alcohol, filtering the solution, decanting after twenty-four hours’ standing ; freezing at 0° (32° F.), and expressing. It is a colorless, odorless, tasteless oil; soluble in alcohol and ether, insoluble in water ; sp. gr. 0.92. Trinitro-glycerin—Nitro-glycerin — CH (ONO.,)3—227—used as an explosive, both pure and mixed with other substances, in dynamite, giant powder, etc., is obtained by the combined action of H2S04 and HNQ3 upon glycerin. Fuming HN03 is mixed with twice its weight of H2S04 in a cooled earthen vessel; 33 parts by weight of the mixed acids are placed in a porcelain vessel, and 5 parts of glycerin, of 31° Beaume, are gradually added with constant stirring, while the vessel is kept well cooled ; after five minutes the whole is thrown into 5-6 volumes of cold NEUTRAL OILS AND FATS. water; the nitro-glycerin separates as a heavy oil which is washed with cold water. Nitro-glycerin is an odorless, yellowish oil; has a sweetish taste ; sp. gr. 1.6 ; insoluble in water, soluble in alcohol and ether ; not volatile ; crystallizes in prismatic needles when kept for some time at 0° (32: F.) ; fuses again at 8° (40°.4 F.). When pure nitro-glycerin is exposed to the air at 30° (86° F. ) for some time, it decomposes, without explosion and with production of glyceric and oxalic acids. When heated to 100° (212° F.) it volatilizes without de- composition ; at 185° (365° F.) it boils, giving off nitrous fumes ; at 217° (422°.6 F.) it explodes violently ; if quickly heated to 257° (494°.6 F.) it assumes the spheroidal form, and volatilizes without explosion. Upon the approach of flame at low temperatures it ignites and burns with slight decrepitations. When subjected to shock, it is suddenly decomposed into C03; N ; vapor of IUO, and O, the decomposition being attended with a violent explosion. In order to render this explosive less dangerous to handle, it is now usually mixed with some inert substance, usually diatomaceous earth, in which form it is known as dynamite, etc. When taken internally, nitro-glycerin is an active poison, producing effects somewhat similar to those of strychnine ; in drop-doses, diluted, it causes violent headache, fever, intestinal pain, and nervous symptoms. It has been latterly used as a therapeutic agent, and has been used by the homoeopaths under the name of glonoin. NEUTRAL OILS AND FATS. These are mixtures in varying proportions of tripalmitin, tristearin, and triolein, with small quantities of other glycerides, coloring and odor- ous principles, which are obtained from animal and vegetable bodies. The oils are fluid at ordinary temperatures, the solid glycerides being in solution in an excess of the liquid triolein. The fats, owing to a less pro- portion of the liquid glyceride, are solid or semi-solid at the ordinary tem- perature of the air. Members of both classes are fluid at sufficiently high temperatures, and solidify when exposed to a sufficiently low temperature. They are, when pure, nearly tasteless and odorless, unctuous to the touch, insoluble in and not miscible with upon which they float; combus- tible, burning with a luminous flame ; when rubbed upon paper they ren- der it translucent. When heated with the caustic alkalies or in a current of superheated steam, they are saponified, i.e., decomposed into glycerin and a fatty acid. If the saponification be produced by an alkali, the fatty acid combines with the alkaline metal to form a soap (q. u). Most of the fats and many of the oils, when exposed to the air, absorb O, are decomposed with liberation of volatile fatty acids, and acquire an acid taste and odor, and an acid reaction. A fat which has undergone these changes is said to have become rancid. Many of the vegetable oils are, however, not prone to this decomposition. Some of them, by oxida- tion on contact with the air, become thick, hard and dry, forming a kind of varnish over surfaces upon which they are spread ; these are designated as drying or siccative oils. Others, although they become more dense on exposure to air, become neither dry nor gummy ; these are known as non• drying, greasy, or lubricating oils. Under ordinary conditions, oils and melted fats do not mix with 268 MANUAL OF CHEMISTRY. water, and, if shaken with that fluid, form a temporary milky mixture, which, on standing for a short time, separates into two distinct layers, the oil floating on the water. In the presence, however, of small quantities of certain substances, such as albumen, pancreatin (q. v.), ptyalin, etc., the milky mixture obtained by shaking together oil and water does not sepa- rate into distinct layers on standing; such a mixture, in which the fat is held in a permanent state of suspension in small globules in a watery fluid, is called an emulsion. Perfect emulsions may be easily obtained by agitating an oil containing a trace of free oleic acid with a very dilute solution of sodium carbonate and borax. Fixed oils.— These substances are designated as “fixed,” to distinguish them from other vegetable products having an oily appearance, but which differ from the true oils in their chemical composition and in their physical properties, especially in tliaj; they are volatile without decomposition, and are obtained by distillation, while the fixed oils are obtained by expression, with or without the aid of a gentle heat. Palm oil is a reddish-yellow solid at ordinary temperatures, has a bland taste and an aromatic odor. It saponifies readily, and is usually acid and contains free glycerin from spontaneous decomposition. Rape seed and colza oils, produced from various species of Brassica, are yellow, limpid oils having a strong odor and disagreeable taste. Croton-oil—Oleum tiglii (U. S.)—Oleum crotonis (Br.)—varies much in color and activity, according to its source ; that which is obtained from the East is yellowish, liquid, transparent, and much less active than that prepared in Europe from the imported seeds, which is darker, less fluid, caustic in taste, and wholly soluble in absolute alcohol. Croton-oil con- tains, beside the glycerides of oleic, crotonic and fatty acids, about four per cent, of a peculiar principle called crotonol, to which the oil owes its vesicating properties ; it also contains an alkaloid-like substance, also ex- isting in castor-oil, called ricinine. None of these bodies, however, are possessed of the drastic powers of the oil itself. Peanut-oil—Ground-nut oil—an almost colorless oil, very much re- sembling olive-oil, in place of which it is frequently used for culinary purposes, intentionally or otherwise. It is readily saponifiable, yielding two peculiar acids, aracliaic and hypogaic (see Olive-oil). Cotton-seed oil—Oleum gossypii seminis (U. S.)—a pale yellow, bland oil, also resembling olive-oil, for which it is frequently substituted. Almond-oil—Oleum amygdalae expressum (U. S.)—Oleum amygdalae (Br.)—a light yellow oil, very soluble in ether, soluble in alcohol; nearly inodorous ; has a bland, sweetish taste. The pure oil has no odor of bitter almonds. Olive-oil—Oleum olivce (U. S., Br.).—A well-known oil of a yellow or greenish-yellow color, almost odorless, and of a bland and sweetish taste. The finest grades have a yellow tinge and a faint taste of the fruit; they are prepared by cold pressure ; they are less subject to rancidity than the lower grades. Olive-oil is very frequently adulterated, chiefly with poppy- oil, sesame oil, cotton-seed oil and peanut-oil; the presence of the first is detected by Pontet's reagent (made by dissolving 6 parts Hg in 7.5 parts of HN03 of 36° in the cold), which converts pure olive-oil into a solid mass, while an oil adulterated with a drying oil remains semi-solid. A contamination with oil of sesame is indicated by the production of a green color, with a mixture of HN03 and H,SO,. Peanut-oil, an exceedingly common adulterant in this country, is recognized by the following method: ten grams of the oil are saponified ; the soap is decomposed with HC1; the NEUTRAL OILS AND FATS. 269 liberated fatty acids dissolved in 50 c.c. of strong alcohol ; the solution precipitated with lead acetate ; the precipitate washed with ether ; the residue decomposed with hot dilute HC1; the oily layer separated and ex- tracted with strong alcohol ; the alcoholic fluid, on evaporation, yields crystals of arachaic acid, if the oil contains peanut-oil. Cocoa-butter—Oleum theobromce (U. S., Br.)—is, at ordinary tempera- tures, a whitish or yellowish solid of the consistency of tallow, and having an odor of chocolate and a pleasant taste ; it does not easily become ran- cid. The most reliable test of its purity is its fusing-point, which should not be much below 33J (91J.4 F.). Linseed oil—Flaxseed oil—Oleum lini (U. S., Br.)—is a dark, yellowish- brown oil of disagreeable odor and taste. In it oleic acid is, at least par- tially, replaced by linoleic acid, whose presence causes the oil, on exposure to air, to absorb oxygen and become thick and finally solid. This drying power is increased by boiling the oil with litharge (boiled oil). Castor-oil—Oleum ricini (C. S., Br.)—is usually obtained by expression of the seeds, although in some countries it is prepared by decoction or by extraction with alcohol. It is a thick, viscid, yellowish oil, has a faint odor and a nauseous taste. It is more soluble in alcohol than any other fixed vegetable oil, and is also very soluble in ether. It saponifies very readily. Ammonia separates from it a crystalline solid, fusible at 66" (158°.8 F.) ricinolamide. Hot HX03 attacks it energetically, and finally converts it into suberic acid. Whale-oil—Train-oil—obtained by trying out the fat or blubber of the “ right whale” and of other species of balcenoe. It is of sp. gr. 0.924 at 15D (59" F.) ; brownish in color ; becomes solid at about 0° ; has a very nause- ous taste and odor. It is colored yellow by H.,S04; and is blackened by Cl. Neat's-foot oil—is obtained by the action of boiling H20 upon the feet of neat cattle, horses, and sheep, deprived of the flesh and hoofs. It is straw-yellow or reddish-yellow, odorless, not disagreeable in taste, not prone to rancidity, does not solidify at quite low temperatures; sp. gr. at 153 (59° F.) = 0.916. It is bleached, not colored, by chlorine. Lard-oil—Oleum adipis (U. S.)—obtained in large quantities in the United States as a by-product in the manufacture of candles, etc., from pig’s fat. A light yellow oil, used principally as a lubricant; is not colored by H.,S04, but is colored brown by a mixture of H.,SO( and HX03. Tallow-oil—obtained by expression with a gentle heat from the fat of the ox and sheep. Sp. gr. 0.9003 ; light yellow in color. Colored brown by H.2S04. Formerly this oil, under the trade name of “oleic acid,” was simply a by-product in the manufacture of stearin candles; of late years, however, it is specially prepared for the manufacture of oleo-margarine. Cod-liver oil—Oleum morrhuce (U. S., Br.)—is obtained from the livers of cod-fish, either by extraction with water heated to about 80° (176" F.), or by hanging the livers in the sun and collecting the oil which drips from them. There are three commercial varieties of this oil: a. Brown.—Dark brown, with greenish reflections; has a disagreeable, irritating taste ; faintly acid; does not solidify at —13° (8°.6 F.). b. Pale brown.—Of the color of Malaga wine ; has a peculiar odor and a fishy, irritating taste ; strongly acid. c. Pale.—Golden yellow ; deposits a white fat at —13° (8°. 6 F.); has a fresh odor, slightly fishy, and a not unpleasant taste, without after-taste. Pure cod-liver oil, with a drop of H2SO,, gives a bluish-violet aureole, which gradually changes to crimson, and later to brown. A drop of fum- ing HX03 dropped into the oil is sun-ounded. by a pink aureole if the oil 270 MANUAL OF CHEMISTRY. be pure ; if largely adulterated with other fish-oils, the pink color is not observed and the oil becomes slightly cloudy. Fresh cod-liver oil is not colored by rosaniline. If a third of the oil be distilled, the distillate be- comes solid ; while if it be contaminated with vegetable oils, the distillate becomes liquid. Cod-liver oil contains, besides the glycerides of oleic, palmitic and stearic acids, those of butyric and acetic acids ; certain biliary principles (to whose presence the sulphuric acid reaction given above is probably due), a phosphorized fat of undetermined composition ; small quantities of bro- mine and iodine, probably in the form of organic compounds ; a peculiar fatty acid called gadinic acid, which solidifies at 60° (140° F.); and a brown substance called gaduin or gadinine. To which, if to any, of these substances cod-liver oil owes its value as a therapeutic agent is still unknown, although many theories have been advanced. Certain it is, however, that one of the chief values of this oil is as a food in a readily assimilable form. Solid Animal Fats.—The glycerides of stearic, palmitic, and oleic acids exist, in health, in nearly all parts of the body ; in the fluids in solu- tion or in suspension, in the form of minute oil-globules ; incorporated in the solid or semi-solid tissues, or deposited in collections in certain loca- tions, as under the skin, enclosed in cells of connective tissue, in which the mixture of the three glycerides is in such proportion that the contents of the cells are fluid at the temperature of the body. The total amount of fat in the body of a healthy adult is from 2.5 to 5 per cent, of the body-weight, although it may vary considerably from that proportion in conditions not, strictly speaking, pathological. The approximate quantities of fat in 100 parts of the various tissues and fluids, in health, are the following : Urine ? Perspiration 0.001 Vitreous humor .... 0.002 Saliva 0.02 Lymph 0.05 Synovial fluid 0.06 Amniotic fluid 0.2 Chyle 0.3 Mucus 0.4 Blood 0.4 Cartilage 1.3 Bone 1.4 j Bile 1.4 Crystalline lens 2.0 Liver 2.4 Muscle 3.3 Hair 4.2 Milk 4.31 Cortex of brain 5.5 Brain 8.0 Hen’s egg 11.6 White matter of brain. 20.0 Nerve-tissue .. 22.1 Spinal cord 23.6 Fat-tissue 82 7 Marrow 96.0 The amount of fat, under normal conditions, is usually greater in women and children than in men ; generally greater in middle than in old age, although in some individuals the reverse is the case ; greater in the inhab- itants of cold climates than in those of hot countries. In wasting from disease and from starvation the fats are rapidly ab- sorbed, and are again as rapidly deposited when the normal condition of affairs is restored. Besides, as a result of the tendency to corpulence, which in some indi- viduals amounts to a pathological condition, fats may accumulate in cer- tain tissues as a result of morbid changes. This accumulation may be due either to degeneration or to infiltration. In the former case, as when mus- cular tissue degenerates in consequence of long disuse, the natural tissue disappears and is replaced by fat; in the latter case, as in fatty infiltration of the heart, oil-globules are deposited between the natural morphological elements, whose change, however, may subsequently take place by true fatty degeneration, due to pressure. Fatty degeneration of the liver and of other organs occurs also in phthisis, chronic heart, and lung affections, NEUTRAL OILS AND FATS. 271 as a result of overfeeding, from the abuse of alcoholic stimulants, and from the action of certain poisons, especially of phosphorus. Tumors com- posed of adipose tissue occur and are known as “ lipomata.” The greater part of the fat of the body enters it as such with the food. Not unimportant quantities are, however, formed in the body, and that from the albuminoid as well as from the starchy and saccharine constitu- ents of the food. By what steps this transformation takes place is still uncertain, although there is abundant evidence that it does occur. Those fats taken in with the food are unaltered by the digestive fluids, except in that they are freed from their enclosing membranes in the stomach, until they reach the duodenum ; here, under the influence of the pancreatic juice, the major part is converted into a fine emulsion, in which form it is absorbed by the lacteals. A smaller portion is saponified, and the products of the saponification, free fatty acids, soaps, and glycerin, subsequently absorbed by lacteals and blood-vessels. The service of the fats in the economy is undoubtedly as a producer of heat and force by its oxidation ; and by its low power of conducting heat, and the position in which it is deposited under the skin, as a retainer of heat produced in the body. The fats are not discharged from the system in health, except the excess contained in the food over that which the absorbents are capable of taking up, which passes out with the faeces ; a small quantity distributed over the surface in the perspiration and seba- ceous secretion (which can hardly be said to be eliminated) ; and a mere trace in the urine. Butter.—The fat of milk, separated and made to agglomerate by agi- tation, and more or less salted to insure its keeping. It consists of the glycerides of stearic, palmitic, oleic, butyric, capric, caprylic, and caproic acids, with a small amount of coloring matter, more or less water and salt, and caseine. Good, natural butter contains 80-90 per cent, of fat, 6-10 per cent, of water, 2-5 per cent, of curd, and 2-5 per cent, of salt; fuses at from 32°.8 to 34°.9 (91°-94°.8 F.). Butter is adulterated with excess of water and salt, starch, animal fats other than those of butter, and artificial coloring matters. Excess of salt and water are usually worked in together, the former up to 14 per cent, and the latter to 15 per cent. To determine the pres- ence of an excess of water, about 4 grams (60 grains) of the butter, taken from the middle of the lump, are weighed in a porcelain capsule, in which it is heated over the water-bath, as long as it loses weight; it is then weighed again ; the loss of weight is that of the quantity of water in the original weight of butter, less that of the capsule. The proportion of salt is determined by incinerating a weighed quantity of butter and determining the chlorine in the ash by the nitrate of silver method (see Sodium chloride). Roughly, the weight of the ash may be taken as salt. Starch is detected by spreading out a thin layer of butter, adding solution of iodine, and examining under the microscope for purple spots. The detection of foreign fats in butter, formerly a most unsatisfactory problem to the analyst, has now become one which may be answered with great certainty. All of the chemical processes used are based upon a pe- culiar difference in the composition of butter-fat from other animal and vegetable fats and oils. When butter-fat is saponified, it yields from 5 to 8 per cent, of butyric acid and its near liomologues, which are soluble in H O, and may be distilled without suffering decomposition, and from 85.5 to 87.5 of stearic, palmitic, and oleic acids, which are neither soluble in water nor capable of being distilled. The other fats and oils, wFen 272 MANUAL OF CHEMISTRY. saponified, yield mere traces of the volatile or soluble fatty acids, and much larger quantities (95.3 to 95.7 per cent.) of insoluble acids. These variations are utilized directly in some processes, such as those of Hehner and Reichert, in which the percentage of fixed and volatile acids are di- rectly determined. In other processes, such as that of Koettstorfer, advantage is taken of the different neutralizing power of the two groups of acids. Thus, as butyric acid, C4Hs02, and stearic acid, C]fH360„ are each capable of neutralizing KHO, molecule for molecule, it follows that their neutralizing power is in proportion to their molecular weights, and that 56 parts KHO will require for neutralization 88 parts of butyric acid, or 284 parts of stearic acid. For descriptions of processes the student is referred to Allen: “Commercial Organic Analysis,” 2d ed., II. Methods for detecting admixture of foreign fats by physical means are unreliable. One of the best, which may be of service for preliminary test- ing, is that of Angell and Hehner. A pear-shaped bulb of thin glass is made of such size as to displace 1 c.c. water, is weighted with mercury until it weighs 3.4 grams (52.5 grains), and the pointed end closed by fusion. The butter to be tested is fused in a beaker over the water-bath, and when quite fluid is poured out into a test-tube, about f inch diameter and 6 inches long, which is kept moderately warm and upright until the fat has separated in a clear layer above the water, and then immersed in water at 15° (59° F.) until the fat has solidified. The test-tube is then arranged as shown in Fig. 38, the bulb being laid upon the surface of the fat. The water in the beaker is now heated until the globular part of the bulb has just sunk below the surface of the fat, at which time the height of the thermometer is noted ; this is the “sinking-point.” The sinking-point of pure butter is 34°.3 to 36°.3 (93°.7-97°.3 F.), that of oleomargarine is lower, that of butter adulter- ated with other fats is higher. “Oleomargarine” is a product made in imitation of butter, which it resembles very closely in color, taste, odor, and general appearance. Under the original pa- tent, it is made from beef-fat, which is hashed, steamed, and subjected to pressure at a carefully regulated temper- ature. Under this treatment it is separated into two fatty products, one a white solid “ stearine,” the other a faintly yellow oil, “oleo-oil.” This oil is then mixed with milk, the mixture colored and churned. The sub- sequent treatment of the product is the same as that of butter. “Butterine,” “ suine,” etc., are products made, by a modification of the above process, from beef or mutton tallow, lard, and cotton-seed oil. Butter is frequently, and oleomargarine is always, colored with some foreign pigment, “ butter color,” which is usually a preparation of annoto. Soaps—are the metallic salts of stearic, palmitic, and oleic acids ; those of K, Na, and NH4 are soluble, those of the other metals insoluble- Tliose of Na are hard, those of K soft. Soap is made from almost any oil or fat, the best from olive-oil, or pea-* nut, or palm-oil, and lard. The first step in the process of manufacture is the saponification of the fat, which consists in the decomposition of the glyceric ethers into glycerin and the fatty acids, and the combination of the latter with an alkaline metal. It is usually effected by gradually adding fluid fat to a weak boiling solution of caustic soda, or potassa, to Pig. 38. LECITHINS. 273 saturation. From this weak solution the soap is separated by “ salting,” which consists in adding, during constant agitation, a solution of caustic alkali, heavily charged with common salt, until the soap separates in gru- mous masses, which float upon the surface and are separated. Finally the soap is pressed to separate adhering water, fused, and cast into moulds. White castile soap—Sapo (V. S.) Sapo durus {Hr.)—is a Na soap made from olive-oil; strongly alkaline, hard, not greasy, very soluble ; contains 21 per cent. H.O. Sapo mollis [Hr.) is a K soap made from olive oil, and contains an excess of alkali and glycerin. Yellow soap is made from tallow or other animal fat, and contains about £ its weight of rosin. Emplastrum plumbi (V. S. ; Br.) is a lead soap, prepared by saponifying olive oil with litharge. The soaps are decomposed by weak acids, with liberation of the fatty acid ; by compounds of the alkaline earths, with formation of an insolu- ble soap ; and in the same way by most of the metallic salts. LECITHINS—NERVE TISSUE. Lecithin—is a substance first obtained from the yolk of hen’s eggs, and subsequently found to exist in brain-tissue, particularly the gray substance, nerve tissue, semen, blood-corpuscles, blood-serum, milk, bile, and other animal tissues and fluids. As obtained from brain-tissue lecithin is a colorless or faintly yellowish, imperfectly crystalline solid, or sometimes of a waxy consistency. It is very hygroscopic. It does not dissolve in H.O, in which, however, it swells up and forms a mass like starch-paste. It dissolves in alcohol or ether, very sparingly in the cold, but readily under the influence of heat. It dissolves in chloroform and in benzol. Lecithin is very prone to decomposition, particularly at slightly elevated temperatures. Its chlo- ride combines with PtCl4 to form an insoluble yellowish chloroplatinate. When an alcoholic solution of lecithin is brought into contact with hot solution of barium hydrate it yields barium glycerophosphate, barium stearate, and choline (see p. 207). This decomposition indicates the constitution of lecithin and its relations to the fats. Glycerophosphoric acid is ortho- phosphoric acid in which an atom of hydrogen has been replaced by the univalent remainder CH.OH—CHOH—CH2—left by the removal of OH from glycerin. /OH 0=P—OH \0—CH — CHOH—CH.pH. In lecithin the remaining oxhydryl groups of the glycerin remainder are removed by union with the basic hydrogen of two molecules of stearic acid, and one of the two remaining basic hydrogen atoms of the phos- phoric acid is displayed by choline. It is obvious that the number of leci- thins is not limited to one, but that many may exist, and probably do, into whose composition any one, or any combination of two, of the acids of the same series as stearic acid may enter. smx /O—N CH—CH—OH 0=P—O—H \0-CH-CH(C, H, H,A). Distearyl-lecithin. 274 MANUAL OF CHEMISTRY. Nerve-tissue, which is exceedingly complex in its chemical composi- tion, and whose chemistry is still in a most rudimentary condition, seems to contain similar constituents in its different parts, which differ, however materially in their quantitative composition. The following substances have been obtained from cerebral tissue : Mineral Substances. Products of Decomposition. Water. Phosphates of Na, K, Ca, Mg. Ferric oxide. Silicic oxide. Traces of sulphates, chlorides, and fluorides. Glycerophosphoric acid. Oleophosplioric acid. Volatile fatty acids. Lactates. Hypoxan thine. Xanthine. Creatine. Albuminoids. Substance related to myosin. Soluble albuminoid, coagulable at 75° (167° F.). Casein (?). Organic Substances. Elastin. Neurokeratin. Neucle'in. Cerebrin. Lecithin. Fats (?). Inosite. Cholesterin. The composition of white and gray matter differs quantitatively, as shown below: Albuminoids Gray matter. ,55.37 White matter. 24.72 Lecithin .. 17.24 9.90 Cholesterin and fats ... 18.68 51.91 Cerebrin ... 0.53 9.55 Extractive matters, insoluble in ether... ... 6.71 3.34 Salts ... 1.46 0.57 Cerebrin is a substance deposited in the crystalline form from hot ethero-alcoliolic extracts of brain-tissue. It is white, very light, odoi’less, and tasteless ; insoluble in water or in cold alcohol or ether. Its solutions are neutral. It does not contain phosphorus. The substance known as protagon, described by Liebreich as having been obtained from brain-tissue, would seem to exist there notably in the white substance of Schwann. It appears to be a compound formed by the union of lecithin with cerebrin. Neurokeratin is a substance, occurring principally in the gray mat- ter, which is insoluble in all solvents, and is not acted upon by digestive liquids. THIRD SERIES OF HYDROCARBONS. 275 THIRD SERIES OF HYDROCARBONS. Series CnHan_a. The terms of this series at present known are: Acetylene C_>H2 I Allyiene C3H4 | Crotonylene CHE I Valerylene C5IE | Rutylene Ci0Hi9 Benylene CJ5Ho, Acetylene—Ethene—C.,Ha—26—exists in coal gas and is formed in the decomposition, by heat or otherwise, of many organic substances. It is best prepared by passing a slow current of coal gas through a narrow tube, traversed by induction sparks; directing the gas through a solution of cuprous chloride ; and collecting and decomposing the precipitate by HC1. It may be obtained by direct synthesis from H and C, by producing the electric arc between carbon points in a glass globe filled with hydrogen. It is a colorless gas, rather soluble in H.,0 ; has a peculiar, disagree- able odor; such as is observed when a Bunsen burner burns within the tube. It forms explosive mixtures with O. It unites with N, under the influence of the electric discharge, to form hydrocyanic acid. Mixed with 01, it detonates violently in diffuse daylight, without the aid of heat. It may be made to unite with itself to form its polymeres benzene, C£H6, styrolene, CJI* and naphthydrene, C10H10. Its presence may be detected by the formation in an ammoniacal solu- tion of cuprous chloride of a blood red precipitate, which is explosive when dry. It is probable that explosions which sometimes occur in brass or copper pipes, through which illuminating gas is conducted, are due to the formation of this compound. Illuminating gas—is now manufactured by a variety of processes, almost every company using some modification of the method, or of the nature and proportion of the materials ; thus we have gas made from wood, from coal, from fats, from petroleum, and by the decomposition of H,0 and subsequent charging of the gas with the vapor of naphtha. The typical process is that in which the gas is produced by heating bituminous coal to bright redness in retorts. As it issues from the re- torts the gas is charged with substances volatile only at high tempera- tures ; these are deposited in the condensers or coolers, and form coal- or gas-tar. From the condensers the gas passes through what are known as “ scrubbers” and “ lime-purifiers,” in which it is deprived of ammoni- cal compounds and other impurities. As it comes from the condensers, coal-gas contains: * Acetylene. * Ethylene. * Marsh-gas. * Butylene. * Propylene. * Benzene. * Styrolene. * Naphthalene. * Acenaphthalene. * Fluorene. * Propyl hydride. * Butyl hydride. f Hydrogen, f Carbon monoxide. \ Carbon dioxide, f Ammonia, f Cyanogen, f Sulphocyanogen. f Hydrogen sulphide, f Carbon disulphide, f Sulphuretted hy- drocarbons. \ Nitrogen, f Aqueous vapor. In passing through the purifiers the gas is freed of the impurities to a greater or less extent, and, as usually delivered to consumers, contains : * Marsh-gas. * Acetylene. I * Ethylene. | t Hydrogen. I \ Nitrogen. I f Aqueous vapor. I f Carbon monoxide. | f Carbon dioxide. * Vapors of Hydrocarbons. * Illuminating constituents. f Impurities. t Diluent. MANUAL OF CHEMISTRY. TETRATOMIC ALCOHOLS. Series CnH,.n + aO, Very few of these compounds have yet been obtained. They may be regarded as the hydrates of the hydrocarbons CnH2)l_2 ; as the glycols are the hydrates of the ethylene series. ch;oi: CHOH Erythrite—Phycite— | = C4H6(OH)4—122—is a product of de- CHOH choh composition of erythrine, C20H22Ol0, which exists in the lichens of the genus rocella. It crystallizes in large, brilliant prisms ; very soluble in H O and in hot alcohol, almost insoluble in ether ; sweetish in taste ; its solutions neither affect polarized light, nor reduce Fehling’s solution, nor are capable of fermentation. Its watery solution, like that of sugar, is capable of dis- solving a considerable quantity of lime, and from this solution alcohol precipitates a definite compound of erythrite and calcium. By oxida- tion with platinum black it yields erythroglucic acid, C4HhOs. AYith fuming HN03 it forms a tetranitro compound, which explodes under the hammer. ACIDS DERIVABLE FROM ERYTHRITE. Theoretically erythrite should, by simple oxidation, yield two acids; one of the series C„Hiri0., and another of the series C„H„„_2Or. Although both of these acids are known, only the first, erythroglucic acid, has been obtained by oxidation of erythrite : CH,OH I CHOH I CHOH I CH,OH COOH I CHOH I CHOH I ch2oh COOH I CHOH I CHOH I COOH Erythrite. Erythroglucic acid. Tartaric acid. Tartaric acids—Acidum tartaricum ( U. S., Br.)—C HcOt—150.— There exist four acids having the composition C HfOr, which differ from each other only in their physical properties, and are very readily converted into one another ; they are designated as : 1st, Bight; 2d, Left; 3d, Inac- tive tartaric acid; 4th, Racemic acid. Right or Dextrotartaric acid crystal- lizes in large, oblique, rhombic prisms, having hemihedral facettes. Solu- tions of the acid and its salts are dextrogvrous. Lcevotartaric acid crystallizes in the same form as dextrotartaric acid, only the hemihedral facettes are on the opposite sides, so that crystals of ACIDS DERIVABLE FROM ERYTHRITE. 277 the two acids, when held facing each other, appear like the reflections one of the other. Its solution and those of its salts are hevogyrous to the same degree that corresponding solutions of dextrotartaric acid are dex- trogyrous. Racemic acid is a compound of the two preceding ; it forms crystals having no hemihedral facettes, and its solutions are without action on polarized light. It is readily separated into its components. Inactive tartaric acid, although resembling racemic acid in its crystalline form and inactivity with respect to polarized light, differs essentially from that acid in that it cannot be decomposed into right and left acids, and in the method of its production. The tartaric acid which exists in nature is the dextrotartaric ; it occurs, both free and in combination, in the sap of the vine and in many other vegetable juices and fruits. Although this is probably the only tar- taric acid existing in nature, all four varieties may and do occur in the commercial acid, being formed during the process of manufacture. Tartaric acid is obtained in the arts from hydropotassic tartrate, or cream of tartar (q. v.). This salt is dissolved in H,0 and the solution boiled with chalk until its reaction is neutral ; calcic and potassic tartrates are formed. The insoluble calcic salt is separated and the potassic salt decomposed by treating the solution with calcic chloride. The united de- posits of calcium-tartrate are suspended in H30, decomposed with the pro- per quantity of H S04, the solution separated from the deposit of calcium sulphate, and evaporated to crystallization. The ordinary tartaric acid crystallizes in large prisms ; very soluble in H.,0 and alcohol; acid in taste and reaction. It fuses at 170° (338° F.) ; at 180° (3563 F.) it loses H .O, and is gradually converted into an anhy- dride ; at 20(F-210o (392°-410° F.) it is decomposed with formation of pyruvic acid, CaH403, and pyrotartaric acid, CrH O(; at higher tempera- tures CO.„ CO, H.,0, hydrocarbons and charcoal are produced. If kept in fusion some time, two molecules unite, with loss of H30, to form tartralic or ditarlaric acid, CgH10On. Tartaric acid is attacked by oxidizing agents with formation of C02, H.,0, and, in some instances, formic and oxalic acids. Certain reducing agents convert it into malic and succinic acids. With fuming HX03 it forms a dinitro-compound, which is very unstable, and which, when decomposed below 36° (96°.8 F.), yields tartaric acid. It forms a precipitate with lime-water, soluble in "an excess of H.,0; in not too dilute solution it forms a precipitate with potassium sulphate solution; it does not precip- itate with the salts of Ca. When heated with a solution of auric chloride it precipitates the gold in the metallic form. As its formula indicates (see above), tartaric acid is tetratomic and dibasic. It has a great ten- dency to the formation of double salts, such as tartar emetic (q. v.). When taken into the economy, as it constantly is in the form of tar- trates, the greater part is oxidized to carbonic acid (carbonates) ; but, if taken in sufficient quantity, a portion is excreted unchanged in the urine and perspiration. The free acid is poisonous in large doses. Citric acid—Aciclum citricum (U. S., Br.)—CrH,0. 4- Aq—-192 -+- 18—is best considered in this place, although its constitution is difterent from that of tartaric acid. It exists in the juices of many fruits—lemon, strawberry, etc. It is obtained from lemon-juice, which is filtered, boiled, and saturated with chalk. The insoluble calcium citrate is separated and decomposed with H. SO j, the solution filtered, and evaporated to crystallization. It crystallizes in large, right rhombic prisms, which lose their aq. at 278 MANUAL OF CHEMISTRY. 100° (212° F.) ; very soluble in water, less soluble in alcohol, sparingly soluble in ether ; heated to 100° (212° F.) it fuses ; at 175 (347° F.) it is decomposed, with loss of H20 and formation of aconitic acid, C6HbOb; at a higher temperature C02 is given off, and itaconic acid, C.H 04, and citraconic acid, C5H604, are formed. Concentrated H ,S04 decomposes it with evolution of CO ; oxidizing agents convert it into formic acid and C02, or into acetone and CO„, or into oxalic and acetic acids and C02. It is tetratomic and tribasic. In the body its salts are oxidized to carbonates. FOURTH SERIES OF HYDROCARBONS. Series C„H2n_4. But one of the lower terms of this series is known ; this is valylene, C.H6, obtained by the action of an alcoholic solution of potash on valery- lene dibromide. It is a liquid, boiling at 45° (113° F.). Among the higher terms of the series are many substances of industrial and medical importance. Terebenthene—C10Hlf—136—is the type of a great number of iso- meric substances existing in the volatile oils or essences. It is the chief con- stituent of oil of turpentine. To obtain it in a state of purity, oil of turpentine is mixed with an alkaline carbonate, and distilled in vacuo over a water-bath, or by frac- tional distillation of the crude oil, those portions being collected which pass over at about 156° (312°.8 F.). Pure terebenthene is a colorless, mobile liquid ; has the peculiar odor of turpentine; boils at about 156° (312°.8 F.) ; burns with a smoky, luminous flame. Obtained from the turpentine of pinus maritima, it is loevogyrous, purified by distillation in vacuo, [a]D = —42 .36, by frac- tional distillation, [a]D = — 40°. 32 ; that obtained from pinus australis is dextrogyrous, [o]D = + 18°.9 ; specific gravity at 0° (32° F.) = 0.8767. It absorbs oxygen rapidly from the air, whether pure or in the com- mercial essence, becoming thick and finally gummy. Oxidizing agents, such as HNO;, attack it energetically, causing it to ignite and burn sud- denly, with separation of a large volume of carbon. HC1 unites with it to form a number of compounds, as do also HI and HBr—all the compounds having the odor of camphor. When mixed with HN03, diluted with alco- hol, and exposed to the air, it forms a crystalline pseudo-glycol, terpine. Cl, Br and I form compounds of substitution or of addition. Turpentine—Terebenthina (U. S.)—is the name given to the concrete juice of various species of trees of the genera Pinus, Abies, and Larix, which consist of terebenthene, its isomeres, and resinous and other sub- stances. The product differs in composition and properties according to the kind of tree from which it is produced. White turpentine—Common American turpentine—obtained from Pinus palustris and P. tceda; is yellowish-white, semi-fluid at summer tempera- ture, hard and solid when cooled ; on exposure to air it becomes dry, hard, and brittle. It is usually subjected to distillation near the jilace of its col- lection, by which process it is separated into the volatile oil, or essence of turpentine (q. v.), and rosin, or colophony (q. v.). European turpentine— Bordeaux turpentine—obtained from P. sylvestris and P. maritima. Canada turpentine—Canada balsam—Balsam of fir—Terebenthina canadensis (U. S.) FOURTH SERIES OF HYDROCARBONS. —is from abies balsamea. It is a tenacious semi-solicl, of the consistency of honey when fresh, colorless or yellowish, sticky, bitter in taste, and having a balsamic odor; when long exposed to the air, or when heated over the water-bath, its volatile constituents are lost, and it is converted into a hard brittle mass. Venice turpentine—produced from larix Europcea— is a thick, viscid liquid, yellowish or greenish in color ; soluble in alcohol; does not concrete as readily as other turpentines. Chian turpentine, the product of pistachia terebinth us, is a thick, greenish-yellow liquid. Essence or Turpentine—Oil of turpentine—Spirits of turpentine—Oleum terebinthince (U. S., Ur.)—is the volatile product of the distillation of tur- pentine. It is not identical with terebenthene, although that substance is its main constituent; it contains also hydrocarbons isomeric with turpen- tine and substances containing oxygen, which either pre-exist in the turpen- tine, or, more usually, result from the method of preparing the oil. "When recently distilled, it is a colorless, limpid, neutral liquid ; sp. gr. 0.8G ; usually Lcvogyrous, sometimes dextrogyrous. When exposed to the air it rapidly becomes yellow and viscid. The action of reagents upon it is practically the same as upon terebenthene. The number of isomerides existing in oil of turpentine is very great ; some are optically active, others inactive ; they also vary in their sp. gr., fusing- or boiling-points, and capacity for absorbing oxygen. Isomeres of Terebenthene.—There exist a great number of bodies, the products of distillation of vegetable substances, which are known as essences, essential oils, volatile oils or distilled oils. They resemble each other in being odorous, oily, sparingly soluble in water, more or less soluble in alcohol and ether ; colorless or yellowish, inflammable, and prone to be- come resinous on exposure to air. They are not simple chemical com- pounds, but mixtures, and in many of them the principal ingredient is a hydrocarbon, isomeric with terebenthene, and consequently having the composition nC1(,H1B. Some contain hydrocarbons, others aldehydes, acet- ones, phenols, and ethers. Of the numerous other hydrocarbons closely related to terebenthene, but two require further consideration as being the principal constituents of caoutchouc and gutta-percha. Caoutchouc—India-rubber—is a peculiar substance existing in sus- pension in the milky juice of quite a number of trees growing in warm climates. It is, when pure, a mixture of two hydrocarbons—caoutchene, C10H,6, and isoprene, C H3. The commercial article is yellowish-brown; sp. gr. 0.919 to 0.942 ; soft, flexible ; almost impermeable, but still capable of acting as a dialyzing membrane when used in sufficiently thin layers. It is insoluble in H.,0 and alcohol, both of which, however, it absorbs by long immersion, the former to the extent of 25 per cent., and the latter of 20 per cent., of its own weight; it is soluble in ether, petroleum, fatty and essential oils ; its best solvent is carbon disulphide, either alone, or, better, mixed with 5 parts of absolute alcohol. It is not acted upon by dilute mineral acids, but is attacked by concen- trated HNO, and H,,SO„ and especially by a mixture of the two. Alkalies tend to render it tougher, although a solution of soda of 40° B. renders it soft after an immersion of a few hours. Cl attacks it after a time, de- priving it of its elasticity, and rendering it hard and brittle. When heated it becomes viscous at 145° (293° F.), and fuses at 170°-180° (347°-356 F.) to a thick liquid, which, on cooling, remains sticky and only regains its primitive character after a long time. On contact with flame it ignites, 280 MANUAL OF CHEMISTRY. burning with a reddish, smoky flame, which is extinguished with dif- ficulty. The most valuable property of india-rubber, apart from its elasticity, is that which it possesses of entering into combination with S to form what is known as vulcanized rubber, which is produced by heating together the normal caoutchouc and S to 130°-150 (26Gc-302 F.). Ordinary vulcanized rubber differs materially from the natural gum in its properties ; its elas- ticity and flexibility are much increased; it does not harden when ex- posed to cold ; it only fuses at 200° (392° F.) ; finally, it resists the action of reagents, of solvents, and of the atmosphere much better than does the natural gum. Frequently rubber tubing is too heavily charged with sulphur for cer- tain chemical uses, in which case it may be desulphurized by boiling with dilute caustic soda solution. Hard rubber, vulcanite, or ebonite, is a hard, tough variety of vulcanized rubber, susceptible of a good polish, and a non-conductor of electricity. It contains 20 to 35 per cent, of S (the ordinary vulcanized rubber contains 7 to 10 per cent.). Gutta-percha—is the concrete juice of isonandra gutta. It is a tough, inelastic, brownish substance, having an odor similar to that of caout- chouc ; at ordinary temperatures it is rather hard, but when warmed it becomes soft and may be moulded, or even cast, so as to assume any form, which it retains on cooling ; it may be welded at slightly elevated temper- atures, is a good insulating and waterproofing material, and is tough and pliable. It is insoluble in water, alkaline solutions, dilute acids, includ- ing hydrofluoric, and in fatty oils ; it is soluble in benzene, oil of turpentine, essential oils, chloroform, and especially in carbon disulphide. A solution in chloroform is known as traumaticine or Liq. gutta perchce (U. S.), and is used to obtain, by its evaporation, a thin film of gutta-percha over parts which it is desired to protect from the air. It is attacked by HN03 and H.,S04. When exposed to air and light, it is gradually changed from the sur- face inward, assuming a sharp, acid odor, becoming hard and cracked, and even a conductor of electricity. Gutta-percha is a more complex substance than caoutchouc, and seems to be made up of three substances : Gutta, C2nH8,, 75-82 per cent., a white, tough substance, fusing at 150° (302° F.), soluble in the ordinary solvents of gutta-percha, but insoluble in alcohol and ether. Albane, C„nH3202, 14- 19 per cent., a white, crystalline resin, heavier than water, fusible at 160c (320° F.) ; soluble in benzene, essence of turpentine, carbon disulphide, ether, chloroform, and hot absolute alcohol; not attacked by HC1. Flu- viale, 4-6 per cent., C nH. O, a yellowish resin, slightly heavier than water, hard and brittle at 03 (32° F.), soft at 50° (122 F.), liquid at 100 (212° F.); soluble in the solvents of gutta-percha. Camphors and Resins.—Most of the essential oils yield on distilla- tion two products of different boiling-points; one of these is a hydrocarbon, in most instances of the terebenthene series, liquid at ordinary tempera- tures, and sometimes known as an eleoptene. The other, of higher boiling- point, and solid at ordinary temperatures, designated a stearoptene, is an oxidized product, and either exists as such in the vegetable exudation, or is produced under subsequent treatment. The camp>hors are probably aldehydes or alcohols corresponding to hydrocarbons related to tereben- thene, although their constitution is still uncertain. , Common camphor—Japan camphor—Laurel camphor—Campholic aldehyde—Camphora (U. S., Br.)—C H Q—152.—Three modifications are FOURTH SERIES OF HYDROCARBONS. 281 known, which seem to differ from each other only in their action upon polarized light: (1.) Dextro camphor = camphore officinarum; obtained from laurus camphora—[aju = +47 .4. (2.) Laevo camphor; obtained from matricaria postlaniam—[a]„ = —47°.4. (3.) Inactive camphor, obtained from the essential oils of rosemary, sage, lavender, and origanum. The first is the ordinary camphor of the shops. It is a white, translu- cent, crystalline solid ; sp. gr. 0.986-0.996, hot and bitter in taste ; aro- matic ; sparingly soluble in H.,0 ; quite soluble in ether, acetic acid, metliylic and ethylic alcohols and the oils ; fuses at 175° (347° F.); boils at 204° (399°. 2 F.); sublimes at all temperatures. It ignites readily and burns with a luminous flame. Cold HXO dis- solves it, and from the solution H.,0 precipitates it unchanged. Boiling or potassium permanganate, oxidizes it to dextro camphoric acid, C10Hlt.O4. Concentrated H S04 forms with it a black solution, from which H O precipitates an oily material called camphene. Distilled with P..O., it yields cymene, C10H14. Alkaline solutions, by long heating under pressure, convert it into camphic acid, CinHnO.,, and horneol. Cl attacks it with difficulty. Br unites with it to form an unstable compound, which forms ruby-red crystals having the composition CI0H]4OBr„. These crystals, when heated to 80°-90° F.), fuse and give off HBr, there re- maining an amber-colored liquid, which solidifies on cooling and yields, by recrystallization from boiling alcohol, long, hard, rectangular crystals of monobromo camphor—camphora monobromata (U. S.)—C10H)6OBr. When vapor of camphor is passed over a mixture of fused potash and lime, heated to 300°-400° (572°-752° F.), it unites directly with the potash to form the K salt of campholic acid, C10H)8O„. Borneol—Borneo camphor— Camphol— Camphyl alcohol—Ci(H O— 154—is usually obtained from dryobalanops camphora, although it may be obtained from other plants, and even artificially by the hydrogenation of laurel camphor. The product from these different sources is the same chemically, so far as we can determine, but varies, like the modifications of camphor, in its action on polarized light. It forms small, white, transparent, friable crystals ; has an odor which recalls at the same time those of laurel camphor and of pepper ; has a hot taste ; is insoluble in water, readily soluble in alcohol, ether, and acetic acid ; fuses at 198° (388°.4 F.), boils at 212° (413 .6 F.). It is a true alcohol, and enters into double decomposition with acids to form ethers. When heated with P.20., it yields a hydrocarbon, borneene, Ci(,H1(.. Oxidized by HNO,, it is converted into laurel camphor. ‘ Menthol—Menthyl alcohol—C10H„nO—156—exists in essential oil of peppermint. It crystallizes in colorless prisms ; fusible at 363 (96 .8 F.); sparingly soluble in water ; readily soluble in alcohol, ether, carbon disul- phide, and in acids. Corresponding to it are a series of menthyl ethers. Eucalyptol—C10H., 0—180—is contained in the leaves of eucalyptus globulus ; it is liquid at ordinary temperatures, and boils at 175J (347J F.) ; by distillation with phosphoric anhydride it yields eucalyptene, C12H1R. Terpine— Terebenthene bihydrate—C](H1 P,2H.,0 + Aq-—172 + 18—is sometimes spontaneously deposited from oil of turpentine containing water ; it may be obtained by frequently agitating for a month or more a mixture of oil of turpentine, alcohol, and ordinary nitric acid. It forms fine, large, rhombic prisms ; sp. gr. 1.0994 ; sparingly soluble in cold water; soluble in hot water, alcohol, and ether; fusible at 103 (217 .4F.). T erpinol—(C, 0H, 6)2H.,0 —290—is formed when terpine in solution in warm water is treated with a very small quantity of H„S04 or HC1, and 282 MANUAL OF CHEMISTRY. distilled. It is a colorless liquid ; has an odor of hyacinth ; sp. gr. 0.852 ; boils at 168° (334°.4 F.), at which temperature it suffers partial decompo- sition. It appears to possess the function of an ether. Resins—are generally the products of oxidation of the hydrocarbons allied to terebentliene ; are amorphous (rarely crystalline) ; insoluble in water ; soluble in alcohol, ether, and essences. Many of them contain acids. They may be divided into several groups, according to the nature of their constituents : (1.) Balsams, which are usually soft or liquid, and are distinguished by containing free cinnamic or benzoic acid (q. v.). The principal members of this group are benzoin, liquidambar, Peru balsam, styrax, and balsam tolu. (2.) Oleo-resins consist of a true resin mixed with an oil, and usually with an oxidized product other than cinnamic or benzoic acid. The principal members of this group are Buryundy and Canada pitch, Mecca balsam, and the resins of capsicum, copaiva, cubebs, elemi, labdanum, and lupulin. (3.) Gum-resins are mixtures of true resins and gums. Many of them are possessed of medicinal qualities ; aloes, ammoniac, asafcetida, bdellium, euphorbium, galbanum, gamboge, guaiac, myrrh, olibanum, opoponax, and scammony. (4.) True resins are hard sub- stances obtainable from the members of the three jDrevious classes, and containing neither essences, gums, nor aromatic acids. Such are colophony or rosin, copal, dammar, dragons blood, jalap, lac, mastic, and sandarac. (5.) Fossil resins, such as amber, asphalt, and ozocerite. CARBOHYDRATES. These substances are composed of C, H and O ; they all contain Cg, or some multiple thereof; and the H and O which they contain is always in the proportion of H., to O. Their constitution is still unknown ; prob- ably some are aldehydes, others alcohols and others ethers. Most of them are constituents of animal or vegetable organisms, and have not been obtained by complete synthesis. They are divisible into three groups, the members of each of which are isomeric with each other : I. Glucoses. «(C6H1206.) +Glucose. (Dextrose.) — Ltevulose. Mannitose. +Galactose. Inosite. — Sorbin. —Eucalin. n. Saccharoses. 4- Saccharose. + Lactose. -I-Maltose. + Melitose. + Melezitose. Trehalose. +Mycose. Synanthrose. +Parasacch arose III. Amyloses. «(CeHia06.) +Starch. + Glycogen. -t- Dextrin. — Inulin. Tunicin. Cellulose. Gums. Glucoses, C6H1206—180. Glucose—Grape-sugar—Dextrose—Liver-sugar—Diabetic sugar.—The substance from which this group takes its name exists in all sweet ancl acidulous fruits; in many vegetable juices; in honey; in the animal economy in the contents of the intestines, in the liver, bile, thymus, heart, lungs, 283 GLUCOSES. blood, and in small quantity in the urine. Pathologically it is found in the saliva, perspiration, fieees, and largely increased in the blood and urine in diabetes meliitus (see below). It may also be obtained by decomposi- tion of certain vegetable substances called glucosides (q. v.). It is prepared artificially by heating starch or cellulose for 24 to 36 hours with a dilute mineral acid (H.,S04). Glucose obtained by this method is liable to contamination with traces of arsenic, which it receives from the H,SOt. Starch is also converted into glucose by the influence of diastase, formed during the germination of grain. Glucose crystallizes with difficulty from its aqueous solution, in white, opaque, spheroidal masses containing 1 aq.; from alcohol in fine, trans- parent, anhydrous prisms; at about 605 (140° F.) in dry air the hydrated variety loses H O. It is soluble in all proportions in hot H.,0 ; verv solu- ble in cold H O ; soluble in alcohol. It is less sweet and less soluble than cane sugar. Its solutions are dextrogyrous : [a] D = + 52°.85. At 170° (338° F.) it loses H O and is converted into glucosan, C;.Hl0Or,. Hot dilute mineral aci Is convert it into a brown substance, ulmic acid, and, in the presence of air, formic acid. It dissolves in concentrated H,S04, without coloi'ation, forming sulphoglucic acid. Cold concentrated HNO, converts it into nitro-glucose; hot dilute HNOa oxidizes it to a mixture of oxalic and oxysaccharic acids. With organic acids it forms ethers. Its solutions dissolve potash, soda, lime, baryta, and the oxides of Pb and Cu, with which it forms compounds. When its solutions are heated with an alkali they assume a yellow or brown color, and give off a molasses-like odor, from the formation of glucic and melassic acids. Glu- cose in alkaline solution exerts a strong reducing action, which is favored by heat; Ag, Bi, and Hg are precipitated from their salts ; and cupric are reduced to cuprous compounds with separation of cuprous oxide. In the presence of yeast, at suitable temperatures, glucose undergoes alco- holic fermentation. Physiological.—The greater part of the glucose in the economy in health is introduced with the food, either in its own form or as other car- bohydrates, which by digestion are converted into glucose ; a certain quantity is also produced in the liver at the expense of glycogen, a for- mation which continues for some time after death. In some forms of diabetes the production of glucose in the liver is undoubtedly greatly increased. The quantity of sugar normally existing in the blood varies from 0.81 to 1.231 part per thousand ; in diabetes it rises as high as 5.8 parts per thousand. Under normal conditions, and with food not too rich in starch and saccharine materials, the quantity of sugar eliminated as such is exceed- ingly small—so small indeed that some observers have contested the fact of any being eliminated in health. It is oxidized in the body, and the ultimate pro lucts of such oxidation eliminated as C02 and H.20. W hetlier or no intermediate products are formed, is still uncertain ; the probability, however, is that there are. The oxidation of sugar is impeded in diabetes. Where this oxidation, or any of its steps, occurs, is at present a matter of conjecture merely ; if, as is usually believed, glucose disappears to a marked extent in the passage of the blood through the lungs, the fact is a strong support of the view that its transformation into CO., and H„0 does not occur as a simple oxidation, as the notion that sugar or any other sub- stance is “ burned ” in the lung, beyond the small amount required by the nutrition of the organ itself, is scarcely tenable at the present day. So long as the quantity of glucose in the blood remains at or below 284 MANUAL OF CHEMISTRY. the normal percentage, it is not eliminated in the urine in quantities appreciable by the tests usually employed ; when, however, the amount of glucose in the blood surpasses this limit from any cause, the urine becomes saccharine, and that to an extent proportional to the increase of glucose in the circulating fluids. The causes which may bring about such an increase are numerous and varied ; many of them are entirely consistent with health, and the mere presence of increased quantities of sugar in the urine is no proof, taken by itself, of the existence of diabetes. Sugar is detectable by the ordinary tests in the urine under the fol- lowing circumstances : Physiologically.—(1.) In the urine of pregnant women and during lac- tation. It appears in the latter stages of gestation and does not disappear entirely until the suppression of the lacteal secretion. (2.) In small quantities in sucking children from eight days to two and one-half months. (3.) In the urine of old persons (seventy to eighty years). (4.) In those whose food contains a large amount of starchy or sac- charine material. To this cause is due the apparent prevalence of diabetes in certain localities, as in districts where the different varieties of sugar are produced. Pathologically.—(1.) In abnormally stout persons, especially in old per- sons and in women at the period of the menopause. The quantity does not exceed 8 to 12 grams per 1,000 c.c. (8.5-5.5 grains per ounce), and disappears when starchy and saccharine food is withheld. This form of glycosuria is liable to develop into ti'ue diabetes when it appears in young persons. (2.) In diseases attended with interference of the respiratory processes —lung diseases, etc. (3.) In diseases where there is interference with the hepatic circulation —hepatic congestion, compression of the portal vein by biliary calculi, cirrhosis, atrophy, fatty degeneration, etc. (4.) In many cerebral and cerebro-spinal disturbances—general paresis, dementia, epilepsy ; by puncture of the fourth ventricle. (5.) In intermittent and typhus fevers. (6.) By the action of many poisons—carbon monoxide, arsenic, chloro- form, curari; by injection into an artery of ether, ammonia, phosphoric acid, sodium chloride, amyl nitrite, glycogen. (7.) In true diabetes the elimination of sugar in the urine is constant, unless arrested by suitable regulation of diet, and not temporary, as in the conditions previously mentioned. The quantity of urine is increased, some- times enormously, and it is of high sp. gr. The elimination of urea is in- creased absolutely, although the quantity in 1,000 c.c. may be less than that normally existing in that bulk of urine. The quantity of in diabetic urine is sometimes enormous ; an elimination of 200 grams (6.4 ounces) in twenty-four hours is by no means uncommon ; instances in which the amount has reached 400 to 600 grams (12.9-19.3 ounces) are recorded, and one case in which no less than 1,376 grams (45 ounces) were discharged in one day. The elimination is not the same at all hours of the day ; during the night less sugar is voided than during the day ; the hourly elimination increases after meals, reaching its maximum in 4 hours, after which it diminishes to reach the minimum, in 6 to 7 hours, when it may disappear entirely ; this variation is more pronounced the more copious the meal. It is obvious from the above, that, in order that quantitative determinations of sugar in urine shall be of clinical value, it is necessary GLUCOSES that the determination be made in a sample taken from the mixed urine of twenty-four hours. The relation existing between the quantity of sugar in the blood and its elimination by the urine in diabetes is well shown by the following re- sults of Pavy, which also show the beneficial effects of restricting .the diet: Urine. Blood. Quantity in Specific Sugar excreted Sugar in Sugar in 24 hours. gravity. iu 24 hours. 1,0UU parts. 1,000 part Case I. Mixed diet 6608 c.c. 1040 751.6 grams. 109.91 5.763 Case II. Mixed diet 6474 c.c. 1041 633.0 grams. 245 2 grams 94.08 5.545 1031 1036 61 34 2 625 Case III. Mixed diet 5878 c.c. 567.7 grams. 115.8 grams. 93.39 4.970 Case III. Restricted diet 2470 c.c. 1033 45.49 2.789 Case IV. Partly restricted diet.. 1704 c.c 1036 21.81 grams. 48.11 1.848 Case IV. Partly restricted diet, l d-i months later ... i 852 c c 1034 14.40 grams. 1.543 Analytical Characters.—A saccharine urine is usually abundant in quantity, pale in color, of high sp. gr., covered with a persistent froth on being shaken, and exhales a peculiar odor ; when evaporated it leaves a sticky residue. The presence of glucose in urine is indicated by the following tests: If the urine be albuminous, it is indispensable that the albumen be separated before any of the tests for sugar are applied ; this is done by adding one or two drops of acetic acid, or, if the urine be alkaline, just enough acetic acid to turn the reaction to acid, and no more, heating over the water-bath until the albumen has separated in flocks, and filtering. (1.) When examined by the polarimeter (see p. 36) it deviates the plane of polarization to the right. (2.) When mixed with an equal volume of liquor potass c and heated, it turns yellow, and, if sugar be abundant, brown. A molasses-like odor is observable on adding HXO,, (Moore’s test). (3.) The urine, rendered faintly blue with indigo solution and faintly alkaline with sodium carbonate, and heated to boiling without agitation, turns violet and then yellow if sugar be present; on agitation the blue color is restored (Mulder-Neubauer test). (4.) About 1 c.c. of the urine, diluted with twice its bulk of water, is treated with two or three drops of cupric sulphate solution and about 1 c c. of caustic potassa solution ; if sugar be present the bluish precipi- tate is dissolved on agitation, forming a blue solution ; the clear blue fluid, w'lien heated to near boiling, deposits a yellow, orange, or red precipitate of cuprous oxide if sugar be present (Trommer's test). In the applica- tion of this test an excess of cupric sulphate is to be avoided, lest the color be masked by the formation of the black cupric oxide. Sometimes no precipitate is formed, but the liquid changes in color from blue to yellow ; this occurs in the presence of small quantities of cupric salt and large quantities of sugar, the cuprous oxide being held in solution by the excess of glucose ; in this case the test is to be repeated, using a sample of urine more diluted with water. In some instances, also, the reaction is interfered with by excess of normal constituents of the urine, uric acid, creatinine, coloring matter, etc., and instead of a bright precipitate, a muddy deposit is formed ; when this occurs the urine is heated with ani- MANUAL OF CHEMISTRY. mal charcoal and filtered ; the filtrate evaporated to dryness ; the residue extracted with alcohol ; the alcoholic extract evaporated ; the residue re- dissolved in water, and tested as described above. (5.) Four or five c.c. of Feliling’s solution (see p. 287) are heated in a test-tube to boiling ; it should remain unaltered. The urine is then added guttatim ; if it c'ontain sugar, the mixture turns green, and a yellow or red precipitate of cuprous oxide is formed, usually darker in color than that obtained by Trommer’s test. The absence of glucose is not to be in- ferred until a bulk of urine equal to that of the Fehling's solution used has been added, and the mixture boiled from time to time without the formation of a precipitate. This test is the most convenient and the most reliable for clinical purposes. (6.) A few c.c. of the urine are mixed in a test-tube with an equal volume of solution of sodium carbonate (1 pt. crystal, carbonate and 3 pts. water), a few granules of bismuth subnitrate are added, and the mixture boiled for some time (until it begins to “ bump,” if necessary). If sugar be present, the bismuth powder turns brown or black by reduction to elementary bismuth (Boettgers test). No other normal constituent of the urine reacts with this test; a fallacy is, however, possible from the pres- ence of some compound, which, by giving up sulphur, may cause the formation of the black bismuth sulphide ; to guard against this, when an affirmative result has been obtained, another sample of urine is rendered alkaline and boiled with pulverized litharge; the powder should not turn black. (7.) A solution of sugar, mixed with good yeast and kept at 25° (77° F.) is decomposed into C02 and alcohol. To apply the fermentation-test to urine, take three test-tubes, A, B, and C, place in each some washed (or compressed) yeast, fill A completely with the urine to be tested, and place it in an inverted position, the mouth below the surface of some of the same urine in another vessel (the entrance of air being prevented, during the inversion, by closing the opening of the tube with the finger, or a cork on the end of a wire, until it has been brought below the surface of the urine). Fill B completely with some urine to which glucose has been added, and C with distilled water, and invert them in the same way as A ; B in saccharine urine, and C in distilled water. Leave all three tubes in a place where the temperature is about 25° (77° F.) for twelve hours, and then examine them. If gas have collected in B over the surface of the liquid, and none in A, the urine is free from sugar ; if gas have collected in both A and B, and not in C, the urine contains sugar ; if no gas have col- lected in B, the yeast is worthless, and if any gas be found in C, the yeast itself has given oft* C02. In the last two cases the process must be repeated with a new sample of yeast. Quantitative Determination of Glucose.—(1.) By the polarimeter.— The filtered urine is observed by the polariscope (see p. 38) and the mean of half a dozen readings taken as the angle of deviation ; from this the percentage of sugar is determined by the formula p — —- 7, in which o!Z.OO X t p = the weight, in grams, of glucose in 1 c.c. of urine ; a = the angle of deviation ; l = the length of the tube in decimetei’s. The same formula may be used for other substances by substituting for 52.85 the value of [a]D for that substance. If the urine contain albumen, it must be removed be- fore determining the value of a. (2.) By specific gravity : Robert's method.—The sp. gr. of the urine is carefully determined at 25° (77" F.); yeast is then added, and the mixture GLUCOSES. 287 kept at 25° (77° F.) until fermentation is complete ; the sp. gr. is again observed, and will be found to be lower than before. Each degree of dim- inution represents 0.2196 gram of sugar in 100 c.c. (1 grain per ounce) of iu-ine. (3.) By Fehling’s solution.—Of the many formula? for Fehling’s solu- tions, the one to which we give the preference is that of Dr. Piffard. Two solutions are required : I. Cupric sulphate (pure, crystals) 51.98 "rams. Water 500.0 c.c. II. Rochelle salt (pure, crystals) 259.9 grams. Sodic hydrate solution, sp. gr. 1.12 1000.0 c.c. When required for use, one volume of No. I. is mixed with two vol- umes of No. II. The copper contained in 20 c.c. of this mixture is pre- cipitated as cuprous oxide by 0.1 gram glucose. To use the solution, 20 c.c. of the mixed solutions are placed in a flask of 250-300‘c.c. capacity, 40 c.c. of distilled water are added, the Avliole thoroughly mixed and heated to boiling. On the other hand, the urine to be tested is diluted with four times its volume of water if poor in su- gar, and with nine times its volume if highly saccharine (the degree of di- lution required is, with a little practice, determined by the appearance of the deposit obtained in the qualitative testing); the water and urine are thoroughly mixed and a burette filled with the mixture. A few drops of aqua ammonia? are added to the Fehling’s solution and the diluted urine added, in small portions toward the end, until the blue color is entirely discharged—the contents of the flask being made to boil briskly between each addition from the burette. When the liquid in the flask shows no blue color, when looked through with a white background, the reading of the burette is taken ; this reading, divided by five if the urine was diluted with four volumes of water, or by ten if with nine volumes, gives the num- ber of c.c. of urine containing 0.1 gram of glucose ; and consequently the elimination of glucose in twenty-four hours, in decigrams, is obtained by dividing the number of c.c. of urine in twenty-four hours by the result ob- tained above. Example.—20 c c. Fehling’s solution used, and urine diluted with four volumes of water. 36.5 Reading of burette : 36.5 c.c. - = 7.3 c.c. urine contam 0.1 gram o glucose. Patient is passing 2,436 c.c. urine in twenty-four hours. 2 436 —’ Q—= 333.6 decigr. = 33.36 grams glucose in twenty-four hours. 1.0 The accuracy of the determination may be controlled by filtering off some of the fluid from the flask at the end of the reaction ; a portion of the filtrate is acidulated with acetic acid and treated with potassium fer- rocyanide solution; if it turn reddish brown the reduction has not been complete, and the result is affected with a plus error. To another portion of the filtrate a few drops of cupric sulphate solution are added and the mixture boiled ; if any precipitation of cuprous oxide be observed, an ex- cess of urine has been added, and the result obtained is less than the true one. This method, when carefully conducted with accurately prepared and 288 MANUAL OF CHEMISTRY. uxideteriorated solutions, is the best adapted to clinical uses. The copper solution should be kept in the dark, in a well-closed bottle, and the stopper and neck of the No. II. bottle should be well coated with paraffin. (4.) Gravimetric 'method.—When more accurate results than are ob- tainable by Fehling’s volumetric process are desired, recourse must be had to a determination of the weight of cuprous oxide obtained by reduction. A small quantity of freshly prepared Fehling’s solution is heated to boil- ing in a small flask ; to it is gradually added, with the precautions ob- served in the volumetric method, a known volume of urine, such that at the eud of the reduction there shall remain an excess of unreduced copper salt. The flask is now completely filled with boiling corked, and al- lowed to cool. The alkaline fluid is separated as rapidly as possible from the precipitated oxide, by decantation and filtration through a small double filter, and the precipitate and flask repeatedly washed with hot H.,0 until the washings are no longer alkaline ; a small portion of the precipitate re- mains adhering to the Avails of the flask. The filter and its contents are dried and burned in a Aveighed porcelain crucible ; when this has cooled, the flask is rinsed outAvith a small quantity of HNOs; this is added to the contents of the crucible, evaporated over the Avater-batli, the crucible slowly heated to redness, cooled, and Aveighed ; the difference betAveen this last Aveight and that of the crucible 4- that of the filter asli, is the Aveight of cupric oxide, of which 220 parts — 100 parts of glucose. Xj£3Vulose—Uncry stall izab/e sugar—forms the uncrystallizable por- tion of the sugar of fruits and of honey, in Avliich it is associated with glucose ; it is also produced artificially by the prolonged action of boiling water upon inulin; and as one of the constituents of inverted sugar. Lsevulose is not capable of crystallization, but may be obtained as a thick syrup ; very soluble in A\rater, insoluble in absolute alcohol ; it is SAveeter but less readily fermentable than glucose, which it equals in the readiness Avitli which it reduces cupro-potassic solutions. Its prominent physical property, and that to which it owes its name, is its strong left- handed polarization, [a]D = —106° at 15° (593 F.). At 170° (338° F.) it is converted into the solid, amorphous Icevulosan, CrH]0OB. Mannitose—is obtained by the oxidation of mannite. It is a yellow, uncrystallizable sugar, having many of the characters of glucose, but opti- cally inactive. Galactose—sometimes improperly called lactose—is formed by the action of dilute acids upon lactose (milk sugar) as glucose is formed from saccharose. It differs from glucose in crystallizing more readily, in being very sparingly soluble in cold alcohol, in its action upon polarized light, [a]D — +83°.33, and in being oxidized to mucic acid by HN03. Inosite—Muscle-sugar— exists in the liquid of muscular tissue, in the lungs, kidneys, liver, spleen, brain, and blood ; pathologically in the urine in Bright’s, diabetes, and after the use of drastics in uraemia, and in the contents of hydatid cysts ; also in the seeds and leaves of certain plants. What the source and function of inosite in the animal economy may be is still a matter of conjecture. It forms long, colorless, monoclinic crystals, containing 2 Aq., usually arranged in groups having a cauliflower-like appearance. It effloresces in dry air ; has a distinctly SAveet taste ; is easily soluble in water, difficultly in alcohol; insoluble in absolute alcohol and in ether ; it is without action upon polarized light. The position of inosite in this series is based entirely upon its chem- ical composition, as it does not possess the other characteristics of the SACCIIAKOSES. 289 group. It does not enter directly into alcoholic fermentation, although upon contact with putrefying animal matters it produces lactic and butyric acids ; when boiled with barium or potassium hydrate, it is not even col- ored ; in the presence of inosite, potash precipitates with cupric sulphate solution, the precipitate being redissolved in an excess of potash ; but no reduction takes place upon boiling the blue solution. The presence of inosite is indicated by the following reactions: Scherers. —Treated with HNO., the solution evaporated to near dryness, and the residue moistened with ammonium hydrate and calcium chloride, and again evaporated ; a rose-pink color is produced. Succeeds only with nearly pure inosite. Gallois'.—Mercuric nitrate produces, in solutions of inosite, a yellow precipitate, which, on cautious heating, turns red ; the color dis- appears on cooling, and reappears on heating. Saccharoses, C H O —342 Saccharose—Cane-sugar—Beet-sugar—Saccharum (U. S.)—The most important member of the group, exists in many roots, fruits, and grasses, and is produced from the sugar-cane, saccharum officinarum, sorghum, sorghum saccharatum, beet, beta vulgaris, and sugar-maple, acer saccha- rinum. For the extraction of sugar the expressed juice is heated in large pans to about 100° (212° F.) ; milk of lime is added, which causes the precipi- tation of albumen, wax, calcic phosphate, etc.; the clear liquid is drawn off, and “ delimed ” by passing a current of CO, through it; the clear liquid is again drawn oft* and evaporated, during agitation, to the crystal- lizing-point ; the product is drained, leaving what is termed raw or mus- covado sugar, while the liquor which drains oft* is molasses. The sugar so obtained is purified by the process of “ refining,” which consists essentially in adding to the raw sugar, in solution, albumen in some form, which is then coagulated, filtering first through canvas, afterward through animal charcoal; the clear liquid is evaporated in “ vacuum-pans,” at a temper- ature not exceeding 72° (1G1°.6 F.), to the crystallizing-point. The pro- duct is allowed to crystallize in earthen moulds; a saturated solution of pure sugar is poured upon the crystalline mass in order to displace the uncrystallizable sugar which still remains ; and the loaf is finally dried in an oven. The liquid displaced as above is what is known as sugar-house syrup. Pure sugar should be entirely soluble in wrater ; the solution should not turn brown when warmed with dilute potassium hydrate solution ; should not reduce Feliling’s solution, and should give no precipitate with anpno- niuin oxalate. Beet-sugar is the same as cane-sugar, except that, as usually met with in commerce, it is lighter, bulk for bulk. Sugar-candy, or rock-candy, is cane-sugar allowed to crystallize slowly from a concentrated solution with- out agitation. Maple-sugar is a partially refined, but not decolorized va- riety of cane sugar. Saccharose crystallizes in small, white, monoclinic prisms ; or, as sugar- candy, in large, yellowish, transparent crystals ; sp. gr. 1.606. It is very soluble in water, dissolving in about one-third its weight of cold water, and more abundantly in hot water. It is insoluble in absolute alcohol or ether, and its solubility in water is progressively diminished by the addi- 290 MANUAL OF CHEMISTRY. tion of alcohol. Aqueous solutions of cane-sugar are dextrogyrous, [a]u = + 73°.8. When saccharose is heated to 1G0° (320° F.) it fuses, and the liquid, on cooling, solidifies to a yellow, transparent, amorphous mass, known as barley-sugar ; at a slightly higher temperature, it is decomposed into glu- cose and lsevulosan ; at a still higher temperature, H.,(J is given off, and the glucose already formed is converted into glucosan ; at 210° (410° F.) the evolution of HsO is more abundant, and there remains a brown material known as caramel, or burnt sugar; a tasteless substance, insoluble in strong alcohol, but soluble in H20 or aqueous alcohol, and used to com- municate color to spirits ; finally, at higher temperatures, methyl hydride and the two oxides of carbon are given off; a brown oil, acetone, acetic acid, and aldehyde distil over ; and a carbonaceous residue remains. If saccharose be boiled for some time with H.,0, it is converted into inverted sugar, which is a mixture of glucose and lawulose: ClsH22On + H.,0 = C(H ,0( 4- C(.H,oO0. With a solution of saccharose the polarization is dextrogyrous, but, after invertion. it becomes laevogyrous, because the left-handed action of the molecule of lawulose produced, [a]D=— 10G,° is only partly neutralized by the right-handed action of the glucose, [a]D — + 52°.85. This inversion of cane-sugar is utilized in the testing of samples of sugar. On the other hand, it is to avoid its occurrence, and the conse- quent loss of sugar, that the vacuum-pan is used in refining—its object be- ing to remove the H.,0 at a low temperature. Those acids which are not oxidizing agents act upon saccharose in three ways, according to circumstances: (1) if tartaric and other organic acids be heated for some time with saccharose to 100°—120° (212°-248° F.), compounds known as saccharides, and having the constitution of ethers, are formed ; (2) heated with mineral acids, even dilute, and less rapidly with some organic acids, saccharose is quickly converted into in- verted sugar ; (3) concentrated acids decompose cane-sugar entirely, more rapidly when heated than in the cold ; with HC1, formic acid and a brown, flocculent material (ulmic acid ?) are formed; with H,S04, S02 and H.,0 are formed, and a voluminous mass of charcoal remains. Oxalic acid, aided by heat, produces CO„, formic acid, and a brown substance (humine ?). Oxidizing agents act energetically upon cane-sugar, which is a good reducing agent. With potassium chlorate, sugar forms a mixture which detonates when subjected to shock, and which deflagrates when moistened with H,S04. Dilute HN03, when heated with saccharose, oxidizes it to saccharic and oxalic acids. Concentrated HNOa, alone or mixed with H.SOj, converts it into the explosive nitro-saccharose. Potassium per- manganate, in acid solution, oxidizes it completely to CO., and H.,0. .Cane-sugar reduces the compounds of Ag, Hg and Au, when heated with their solutions ; it does not reduce the cupro-potassic solutions in the cold, but effects their reduction when heated with them to an extent pro- portional to the amount of excess of alkali present. When moderately heated with liquor potassae, cane-sugar does not turn brown, as does glucose; but by long ebullition it is decomposed by the alkalies much less readily than glucose, with formation of acids of the fatty series and oxalic acid. With the bases, saccharose forms definite compounds called sucrates (improperly saccliarates, a name belonging to the salts of saccharic acid). With Ca it forms five compounds. Hydrate of calcium dissolves readily in solutions of sugar, with formation of a Ca compound, soluble in H20, 291 AMYLOSES. containing an excess of sugar. A solution containing 100 parts of sugar in GOO parts of H,0 dissolves 32 parts of calcic oxide. These solutions have an alkaline taste ; are decomposed, with formation of a gelatinous precipitate, when heated, and, with deposition of calcium carbonate and regeneration of saccharose, when treated with CO.,. Quantities of cal- cium sucrates are frequently introduced into sugars to increase their weight—an adulteration the less readily detected, as the sucrate dissolves with the sugar. Calcium sucrates exist in the liq. calcis mccharatus (Br.). Yeast causes fermentation of solutions of cane-sugar, but only after its conversion into glucose. Fermentation is also caused by exposing a solu- tion of sugar containing ammonium phosphate to the air. During the process of digestion, probably in the small intestine, cane- sugar is converted into glucose. Lactose—Milk-sugar—Lactine—Saccharum lactis (U. S., Br.)—has hitherto been found only in the milk of the mammalia. It may be ob- tained from skim-milk by coagulating the casein with a small quantity of H2S04, filtering, evaporating, redissolving, decolorizing with animal char- coal, and recrvstallizing. It forms prismatic crystals; sp. gr. 1.53 ; hard, transparent, faintly sweet, soluble in G parts of cold and in 2.5 parts of boiling HO ; soluble in acetic acid ; insoluble in alcohol and in ether ; its solutions are dextro- gyrous, [a]n= + 59°.3. The crystals, dried at 100° (2123 F.), contain 1 Aq., which they lose at 150° (302° F.). Lactose is not altered by contact with air. Heated with dilute mineral or with strong organic acids, it is converted into galactose. HX03 oxidizes it to mucic and oxalic acids. A mixture of HN03 and H,S04 converts it into an explosive nitro-compound. With organic acids it forms ethers. With soda, potash, and lime it forms compounds similar to those of sac- charose, from which lactose may be recovered by neutralization, unless they have been heated to 100° (212° F.), at which temperature they are decomposed. It reduces Feliling’s solution, and reacts with Trommer’s test. In the presence of yeast, lactose is capable of alcoholic fermentation, which takes place slowly, and, as it appears, without previous transforma- tion of the lactose into either glucose or galactose. On contact with putrefying albuminoids it enters into lactic fermentation. The average proportion of lactose in different milks is as follows : Cow*, 5.5 per cent. ; mare, 5.5 ; ass, 5.8 ; human, 5.3 ; sheep, 4.2 ; goat, 4.0. When taken internally, it is converted into galactose by the pancreatic secretion ; when injected into the blood, it does not appear in the urine, which, however, contains glucose. Maltose—A sugar closely resembling glucose in many of its proper- ties, is formed along with dextrine during the conversion of starch into sugar by the action of diastase and of the cryptolytes of the saliva and pancreatic juice. It crystallizes as does glucose, but differs from that sugar in being less soluble in alcohol and in exerting a dextrogyratory power three times as great. Amyloses, „(C6H10O5)—nl62. Starch—Amylum (U. S.)—the most important member of the group, exists in the roots, stems, and seeds of all plants. It is prepared from rice, wheat, potatoes, maniot, beans, sago, arrow-root, etc. The com- minuted vegetable tissue is steeped for a considerable time in H20 ren- 292 MANUAL OF CHEMISTRY. dered faintly alkaline with soda ; the softened mass is then rubbed on a sieve under a current of water, which washes out the starch granules ; the washings are allowed to deposit the starch, which, after washing by de- cantation, is dried at a low temperature. Starch is a white powder, having a peculiar slippery feel, or it appears in short columnar masses. The granules of starch differ in size and appearance according to the kind of plant from which they have been ob- tained. They are rounded or egg-shaped masses, having at the centre or toward one end a spot, called the hilum, around which are a series of con- centric lines more or less well marked. Differences in size, shape, and markings of starch granules are shown in Fig. 39. Fig. 39. Starch is not altered by exposure to air, except that it absorbs moisture. Commercial starch contains 18 per cent, of H.,0, of which it loses 8 per cent, in vacuo, and the remaining 10 per cent, at 145° (293° F.). It is insoluble in alcohol, ether and cold water. If 15 to 20 parts of H20 be gradually heated with 1 part of starch, the granules swell at about 55° (131J F.), and at 80° (176° F.) they have reached 30 times their oi'iginal dimensions ; their structure is no longer distinguishable, and they form a translucent, gelatinous mass, commonly known as starch AMTLOSES. 293 paste. In this state the starch is said to be hydrated, and, if boiled with much H..O, and the liquid filtered, a solution of starch passes through, which is opalescent from the suspension in it of undissolved particles. Cold dilute solutions of the alkalies produce the same effects on starch as does hot water. Hydrated starch is dextrogyrous, [«]D = -+- 216°. Dry heat causes the granules of starch to swell and burst; at 200° (392° F.) it is converted into dextrin; at 230° (146° F.) it forms a brownish-yellow, fused mass, composed principally of pyrodextrin. Hydrated starch is converted into dextrin by heating with H.,0 at 160“ (320“ F.), and, if the action be prolonged, the new product is changed to glucose. The amount of starch contained in food vegetables varies from about 5 per cent, in turnips to 89 per cent, in rice, as will be observed in the following table : Composition of Vegetable Foods. Nitrogen- ized matter. Starch. Dextrin, etc. Cellu- lose. Mineral Fat. matter. Carbo- hydrate. Water. Vegetable fibre, etc. Authority Wheat, hard 22.75 58.02 9.50 3.50 2.61 3-02 .... Payen. Wheat, hard 19.50 65.07 7.00 3.0 2.12 2.71 .... Payen. Wheat, hard 20.0 03.80 8.0 3.10 2.25 2.&5 .. Payen. Wheat, serai-hard.. 15.25 70.05 7.0 3.0 1.95 2.75 .... .. [Payen. Wheat, soft 12.05 70.51 0.05 2.80 1.87 2.12 | Payen. Rve 12.50 04.05 14.90 3.10 2.25 2.00 .. ! Payen. Barley 12.90 00.43 10.0 4 75 2 70 3.10 .. Payen. 14.39 00.59 9.25 7.00 5.50 3.25 .. ! Payen. Maize 12.50 07.65 4.0 5.90 S.80; 1.25 .. j Payen. 7.55 88.65 1.0 1.10 0.80 (1.90 .. Payen. 14.45 1.25 1.00 08.48 14.22 .. Payen. Flour 10.80 2.0 1.70 70.50 15.0 .. Letheby. 8.10 1 .00 2.30 51.00 37.0 .. Letheby. Oatmeal 12.00 5.60 3.0 03.80 15.0 .. Letheby. Buckwheat 13.10 04.90 3.50 3.0 2.50 13.0 Payen. Quinoa seeds 22.80 60.80 5.74 5.05 9.53 iVoelcker. Quinoa flour 19.0 00.0 5.0 1 .. 16.0 Voelcker. Horse-bean 30.80 48.30 3.6 1.90 3.50 12.50 .. j Payen. Broad bean.... .... 29 05 55.85 1.05 2.0 3.05 8.40 .. [Payen. White bean 25.50 55.70 2.09 2.80 3.20 9.90 .. Payen. Peas, dried 23.80 5S.70 3.50 2.10 2.10 8.30 .. Payen. Lentils 25.20 56.0 2.40 2.60 2.30 11.50 .. iPaven. Potato 2.50 20.0 1.09 1:04 0.11 1.20 74.0 .. Payen. Potato 2.10 18.80 3.20 0.20 0.70 75.0 .. Letheby. Sweet potato 1.50 16.05 10.20 0.45 0 30 2.0 J 07.50 1.10 Payen. Carrots 1.30 8.40 0.10 0.20 1.0 83.0 Letheby. Parsnip 1.10 9.60 5.80 0.50 1.0 82. M Letheby. Turnip 1.20 5.10 2.10 .. : 0.00 91 0 Letheby. If starcli be ground up with dilute H2S04, after about half an hour the mixture gives only a violet color with I (see below) ; if now the acid be neutralized with chalk and the filtered liquid evaporated, it yields a white, granular product, which differs from starch in being soluble in H O, especially at 50° (122° F.), and in having a lower rotary power, [o]D = + 211°. If the action be prolonged, the value of [a]„ continues to sink until it reaches 4- 73.7°, when the product consists of a mixture of dextrin and glucose. Concentrated HN03 dissolves starch in the cold, forming a nitro-product called xylodin or pyroxam, which is insoluble in H.,0, sol- uble in a mixture of alcohol and ether ; explosive. HC1 and oxalic acid convert starch into glucose. When starch is heated under pressure to 120° (248° F.) with stearic or acetic acid, compounds are formed which seem to be ethers, and to indicate that starch is the hydrate of a trivalent, oxygen- ated radical, (CfH70„)"'. Potash and soda in dilute solution convert starch into the soluble modification mentioned above. 294 MANUAL OF CHEMISTRY. A dilute solution of I produces a more or less intense blue-violet color with starch, either dry, hydrated, or in solution, the color disappearing- on the application of heat, and returning on cooling. If to a solution of starch, blued by I, a solution of a neutral salt be added, there separates a blue, llocculent deposit of the so-called iodide of starch. Iodine renders starch soluble in water, and a soluble iodized starch, Amylum iodatum (U. S.), is obtained by triturating together 19pts. starch, 2 pts. water, and 1 j)t. iodine, and drying below 40° (104° F.). Starch has not been found in the animal economy outside of the ali- mentary canal, in which, as a prerequisite to its absorption, it must be converted into dextrin and glucose. This change is partially effected by the action of the saliva ; more rapidly with hydrated than with dry starch, and more rapidly with the saliva of some animals than that of others ; those of man and of the rabbit acting much more quickly than those of the horse and dog. A great part of the starch taken with the food passes into the small intestine unchanged ; here, under the influence of a pancreatic cryp- tolyte, a further transformation into glucose, and of a portion into lactic and butyric acids, takes place. During the germination of grain, as in the process of malting, a pe- culiar, nitrogenized substance is produced, which is known as diastase. Under the influence of this body the starch is more or less completely converted into glucose, in very much the same way as the conversion occurs in the body. This “ diastatic ” action, whether produced by vegetable or animal processes, does not take place by a simple conversion of starch into glucose, by some such single reaction as that expressed by C(H,0O5 + H,0 = C(,H120(., but by successive stages in which “soluble starch ” is first produced, then several bodies called dextrines, then maltose, and finally glucose. (See Dextrin, p. 295.) ‘ Glycogen occurs in the liver, the placenta, white blood-corpuscles, pus-cells, young cartilage-cells, in many embryonic tissues, and in muscular tissue. During the activity of muscles the amount of glycogen which they contain is diminished, and that of sugar increased. Pure glycogen is a snow-white, floury powder ; amorphous, tasteless, and odorless ; soluble in H20, insoluble in alcohol and ether. In H20 it SAvells up at first, and forms an opalescent solution, which becomes clear on the addition of potash. Its solutions are dextrogyrous to about three times the extent of those of glucose. Dilute acids, ptyalin, pancreatin, extract of liver-tissue, blood, diastase, and albuminoids convert glycogen into a sugar having all the properties of glucose. Cold HN03 converts it into xyloidin ; on boiling, into oxalic acid. Its solutions dissolve cupric hydrate, which is, however, not reduced on boiling. Iodine colors glycogen wine-red. Concerning the method of formation of glycogen in the economy, but little is known with certainty ; there is little room for doubting, however, that while the bulk of the glycogen found in the liver results from mod- ification of the carbohydrates, it may be and is produced from the al- buminoids as well. The ultimate fate of glycogen is undoubtedly its transformation into sugar under the influence of the many substances ex- isting in the body capable of provoking that change. This transformation is continuous in the liver during life, and is accomplished through the same series of intermediary changes into dextrins and maltose as in the case of the conversion of starch into sugar, except that possibly the struct- ure of the dextrins may be different. AMYLOSES 295 Dextrin—British gum—a substance resembling gum arabic in appear- ance and in many properties, is obtained by one of three methods : (1) by subjecting starch to a dry heat of 175° (347° F.); (2) by heating starch with dilute H2S04 to 90J (194° F.) until a drop of the liquid gives only a wine-red color; neutralizing with chalk, filtering, concentrating, precipi- tating with alcohol ; (3) by the action of diastase (infusion of malt) upon hydrated starch. As soon as the starch is dissolved the liquid must be rapidly heated to boiling to prevent saccharification. Commercial dextrin is a colorless, or yellowish, amorphous powder, soluble in HaO in all proportions, forming mucilaginous liquids. When obtained by evaporation of its solution, it forms masses resembling gum arabic in ajDpearance. Its solutions are dextrogyrous, and reduce cupro- potassic solutions under the influence of heat, to amounts varying with the method of formation of the sample. It is colored wine-red by iodine. It is extensively used in the manufacture of mucilage. Recent investigations have shown that by the action of diastase upon starch, four dextrins are produced : 1st, Erythrodextrin, which is colored red by iodine, and which is easily attacked by diastase ; 2d, Achroodextrin a, not colored by iodine ; partially converted into sugar by diastase ; rotary power [a]D = + 210° ; reducing power (glucose = 100) = 12 ; 3d, Achroodextrin (3, not colored by iodine, nor decomposable in 24 hours by diastase ; rotary power + 190° ; reducing power =-12 ; 4th, Achroodex- trin y, not colored by iodine, nor decomposed by diastase ; slowly con- verted into glucose by dilute H3S04 ; rotary power = + 150° ; reducing power — 28. An explanation of this series of transformations has been suggested in the supposition that the molecule of starch consists of 50(C1,,H20Oin) ; that this is first converted into soluble starch 10(C12H.,0O10), and that this is then converted into the different forms of dextrin by a series of hydrations attended by simultaneous formation of maltose, of which the final result might be represented by the equation : 10(Cl2H20O10) + 8(H„0) = 2(CiaH20O10) + 8(CiaH,aOJ Soluble starch. Water. Achroodextrin. Maltose. Cellulose—Cellulin—Lignin—forms the basis of all vegetable tissues ; it exists, almost pure, in the pith of elder and of other plants, in the purer, unsized papers, in cotton, and in the silky appendages of certain seeds. Cotton, freed from extraneous matter by boiling with potash, and after- ward with dilute HC1, yields pure cellulose. It is a white material, having the shape of the vegetable structure from which it was obtained ; insoluble in the usual neutral solvents, but soluble in the deep-blue liquid obtained by dissolving copper in ammonia in contact with air. Vegetable parchment, or parchment paper, is a tough material, possess- ing all the valuable properties of parchment, made by immersing unsized paper for an instant in moderately strong H.SO.., washing thoroughly, and drying. Nitro-cellulose. By the action of HN03 upon cellulose (cotton) three different products of substitution may be obtained : mononitro-cellulose, soluble in acetic acid, insoluble in a mixture of ether and alcohol; dinitro- cellulose, insoluble in acetic acid, soluble in a mixture of ether and alcohol; trinitro-cellulose, soluble in both the above solvents. Gun-cotton or pyroxy- 296 MANUAL OF CHEMISTRY. lin is composed of varying proportions of these three derivatives. When gun-cotton is required as an explosive agent, the process is so managed that the product shall contain the greatest possible proportion of trinitro- cellulose,' the most readily inflammable of the three. When required for the preparation of collodion, for use in medicine or in photography, dinitro- cellulose is the most valuable. To obtain this, a mixture is made of equal weights of HN03 and H2S04 (of each about 5 times the weight of the cot- ton to be treated); in this the cotton is immersed and well stirred for about three minutes, after which it is well stirred in a large vessel of water, washed with fresh portions of water until the washings are no longer pre- cipitated by barium chloride, and dried. Collodion is a solution of dinitro- cellulose in a mixture of three volumes of ether and one volume of alcohol. Celluloid is gun-cotton and camphor compacted under pressure. Gums—are substances of unknown constitution, existing in plants; amorphous ; soluble in water, insoluble in alcohol; converted into glucose by boiling with dilute H2S04. Lichenin is obtained from various lichens by extraction with boiling water, forming a jelly on cooling; it is oxidized to oxalic acid by HN03 ; is colored yellow by iodine ; and is precipitated from its solutions by alcohol. Arabin is the soluble portion of gum arabic and gum Senegal—Acacia (V\ (S'.). To separate it, gum arabic is dissolved in water acidulated with HC1, and precipitated by alcohol. It is a white, amorphous, tasteless sub- stance, which is not colored by iodine ; is oxidized by HN03 to mucic and saccharic acids ; is converted by H.,S04 into a non-fermentable sugar, ara- binose ; and has the composition, C,2H20O10 + 1 Aq. Basxorin constitutes the greater part of gum tragacantli; it is insoluble in water, but swells up to a jelly in that fluid. Cerasin is an insoluble gum exuded by cherry- and plum-trees ; water acts upon it as upon bassorin. AROMATIC SUBSTANCES. The name of aromatic substances was first given to a class of bodies related to benzoic acid, and including a number of products possessed of aromatic odors. At present the meaning of the term has been extended to include a great number of bodies belonging to, or derivable from, the hydrocarbons of the fifth and higher series, all of which may, in fact, be considered as products of addition or of substitution, or both, derivable from benzene, C6HR. A few of these substances, such as benzoic acid, have long been known, and occur in nature in quantities sufficient to readily supply all present demands. Others, such as salicylic acid, although existing in nature, are found in small amount, and are now manufactured artificially by processes which could only have been devised after a knowledge of their constitu- tion was obtained. By far the greater number of aromatic compounds at present known have no existence in nature, and are obtained as products of the laboratory or of manufacturing industries. Among these are many substances for which valuable uses have already been found in the arts and in medicine—e.g., the aniline, anthracene, and naphthalene dyes, carbolic and cresylic acids—while hardly a day passes without a sugges- tion of the practical utility of some substance formerly known only as a “ chemical curiosity.” 297 FIFTH SERIES OF HYDROCARBONS FIFTH SERIES OF HYDROCARBONS Skries C„H2,.-, The hydrocarbons of this series are the starting-points from which the major part of that numerous and important class of substances usually classed as aromatic are obtainable or derivable. Those of the series at present known are : Benzene CBH6 boils at 80°.4 (17P>°. 7 F.) Toluene C7H8 boils at llOVi (.230°. 5 F.) Xylene C8H10 ... .boils at 142°.0 (287°. (i F.) Cumene CjHjcj boils at 151°.4 (304°. 5F.) Cymene • • .boils at ITS0.!) (347°. 0 F.) Laurene CnH16.... boils at 188°.I (370°. 4 F.) Benzene—Benzol—phenyl hydride—C^H,.—78—(not to be confounded with the commercial benzine, a mixture of hydrocarbons of the series C(lH2B+2, obtained from petroleum) does not exist in nature, but is pro- duced in a number of reactions. It is obtained by one or two methods, according as it is required chemically pure or mixed with other sub- stances. To obtain it pure, recourse must be had to the decomposition of one of its derivatives, benzoic acid ; this substance is intimately mixed with 3 pts. slacked lime, and the mixture heated to dull redness in an earthen- ware retort, connected with a wrell-cooled receiver ; the upper layer of dis- tilled liquid is separated, shaken with potassium hydrate solution, again separated, dried by contact with fused calcium chloride, and redistilled over the water-bath. For use in the arts, and for most chemical purposes, benzene is ob- tained from coal- or gas-tar, an exceedingly complex mixture, containing some forty or fifty substances, among which are : Hydrocarbons. Acids. Bases. Benzene, Acenaphthalene. Carbolic. Pyridine. IridoliDe. Toluene. Fluorene. Cresylic. Aniline. Cryptidine. Xylene. Anthracene. Phlorylic. Picoline. Acridine. Cumene. Retene. Rosolic. Lutidine. Coridine. Cymene. Naphthalene. Chrysene. Pyrene. Oxyphenic. Collidine. Leucoline. Rubidine. Viridine. By a primary distillation of coal-tar the most volatile constituents, in- cluding benzene, are separated as light oil; this is washed, first with H„S04, and then with caustic soda, and afterward redistilled ; that portion being collected which passes between 80' and 85° (170 -185° F.). This is the commercial benzene, a product still contaminated with the higher liomologues of the same series, from which it is almost impossible to separate it, but whose presence is rather advantageous than otherwise to the principal use to which benzol is put—the manufacture of aniline dyes. Benzene is a colorless, mobile liquid, having, when pure, an agreeable odor; sp. gr. 0.86 at 15° (59° F.) ; crystallizing at -t-4 .5 (40°.1 F.) ; boiling at 80°.5 (170°. 9 F.) ; very sparingly soluble in water, soluble in alcohol, ether, and acetone. It dissolves I, S, P, resins, caoutchouc, gutta- percha, and almost all the alkaloids. It is inflammable, and burns with a luminous, smoky flame. Benzene unites with Cl or Br to form products of addition, or of sub- stitution ; the corresponding iodine compounds can only be obtained by indirect methods. Sulphuric acid combines with benzene to form a neu- 298 MANUAL OF CHEMISTRY. tral substance, sulpho-benzide, when the anhydrous acid is used, and phenyl- sulphurous acid with the ordinary H2S04. If fuming HN03 of sp. gr. 1.52 be slowly added to benzene, a reddish liquid is formed ; from which, on the addition of H20 a reddish-yellow oil separates, and is purified by washing with H,0 and with sodium car- bonate solution, drying and rectifying. This oily material is mononitro- benzene (see p. 313). If benzol be boiled with fuming HNO,, or if it be dropped into a mixture of HN03 and H.,S04, so long as the fluids mix, a crystalline product, dinitro-benzene, is formed. The constitution of benzene, the nucleus of the aromatic compounds, differs in character from that of the hydrocarbons of the series hitherto considered, and is of importance in connection with the formation of its numerous derivatives. Writing the molecular formulae of the sixth of each of the first three series (the constitution of those of the terebenthene series is still doubtful) we have : First Series. C = II3 I c = h,2 I C = Ha I c = h2 I C = II2 c=h3 c6h]4 Second Series. c = h3 I c = h2 I C = Ha c = h2 I C - II II c = H2 CfHia Third Series. c = h3 I c = h2 i c = h2 c = h2 I c III C-H CeH10 It will be observed that in each of these the chain of C atoms is an open one, and that the series differ in this, that in the first each of the C atoms exchanges with its neighbor a single valence ; in the second two neighboring C atoms exchange two valences between them ; and that in the third there is an exchange of three valences between two neighboring C atoms. And, further, that in terms above the second in the first two series, and the third in the third series, superior liomologues may be considered as formed by interpolation of CH, in the chain of the one next below. In the case of benzene the C atoms are arranged, not in an open, but a closed chain, and exchange with each other alternately one and two va- lences, and consequently the molecular formula of benzol is : H I Hx /C\ /H XC (Y I II /c c\ H \c/ XH I H The superior liomologues of benzene are derived from it by the sub- stitution of CH., for Id, and all the derivatives of benzol are formed by FIFTH SERIES OF HYDROCARBONS. 299 such substitution of a group or groups for an atom or atoms of H, in such a way that they all contain one or more groups of six atoms of C arranged as above : H I * ✓°\ H-C C-C=H3 I II H-C C—H \c/ I H H ! ■ yc\ H-C C —O—H I 11 H—C C—H \C/ I H Toluene. Phenol (carbolic acid). H I H—C C— (NO,)' I II H—C C—H \c/ H H I H—C C—(NHJ' I II H—C C—H \c/ I H Nitro-benzene. Amido-benzene (aniline). The superior homologues of benzene include many isomeres. As they are derivable from benzene by substitution of a hydrocarbon radical or radicals C??H.,/i+j for one or more atoms of hydrogen, the following iso- meres may exist : C,.H((CH,)2 = Dimethylbenzene ) tt CeH5(C,H.) = Ethylbenzene ) 8 10 C(.H = C#H12 CeH4(CH3)(C2H6) = Methylethylbenzene ) Ci,H0(CH,)4 = Tetramethylbenzene CfHi(C.,H,)2 = Diethylbenzene C„H.(C,H„) = Butylbenzene )■ = C10H14 C(,H,(CHs)9(CaH#) = Diraethylethylbenzene | C6H4(CH3)(C3H7) — Methylpropylbenzene J The number of isomeres of the higher terms of the series is further increased by the occurrence of increasing numbers of isomeres in the rad- icals themselves in C.H. and all higher terms. (See graphic formula, p. 172.) In these hydrocarbons and in other derivatives of benzene the six atoms of carbon belonging to benzene constitute what is known as the benzene nucleus, benzene ring, or the principal chain / while the substituted groups are designated as the lateral chains. 300 MANUAL OF CHEMISTRY. Toluene—Toluol—Methyl-benzene—CH.CH—92— exists in the pro- ducts of distillation of wood, coal, etc., and as one of the constituents of commercial benzene. It has been formed synthetically by acting upon a mixture of monobromo-benzene and methyl iodide with sodium. It is a colorless liquid, having a peculiar odor, differing somewhat from that of benzene ; boils at 110°.3 (230°.5 F.) ; does not solidify at —20° ( —4° F.) ; sp. gr. 0.872 at 15° (59° F.) ; almost insoluble in water, solu- ble in alcohol, ether, carbon disulphide. It burns with a bright, but very smoky flame. It yields a number of derivatives similar to those of ben- zene, among which may be mentioned nitro-tolvene and toluidine, the ko- mologues of nitro-benzene and aniline, which accompany those substances in the commercial products ; cresylol, the superior liomologue of carbolic acid, and benzylic alcohol. Xylene—Xylol—Dimethyl-benzene— CfH.(CH,)„ —106 — accompanies its inferior liomologues in coal-tar. When pure it is a liquid of an aro- matic odor; sp. gr. 0.865 at 20° (68° F.) ; boils at 142 (287°.6 F.) ; insoluble in water, soluble in ether, benzene, etc., sparingly soluble in alcohol. There are three isomeric substances having this composition, and differing in the position in which the substituted CIi3 groups are placed. Each of these corresponds to a series of derivatives parallel to those of benzene. Cumene— Gumol—Propyl-benzene—CrHr(C„H.)—120—is obtained by distilling a mixture of cuminic acid and lime, as benzene is prepared from benzoic acid. It is a limpid liquid, having a strong aromal ic odor ; boils at 151°.4 (304°.5 F.) ; insoluble in 11,0, very soluble in alcohol and ether. There are several isomeres of this substance, among which are pseudo- cumene, or trimethyl-benzene, C6H;) (CII3)3, and mesitylene, or methyl-ethyl- ;'jenzene, C6H4 (CHj(C,H;) ; each corresponding to a series of derivatives. Cymene—Gymol.—There are many isomeres, of which one exists ready formed in essence of cumin, and in hemlock. It is a colorless, oily liquid ; has an odor of lemon ; sp. gr. 0.857 at 16° (60°.8 F.) ; boils at 175° (347" F.) ; insoluble in water, but readily soluble in alcohol, ether, and essential oils. HALOID DERIVATIVES. By the substitution of atoms of Cl, Br, or I for the hydrogen of the principal’ and lateral chains of the hydrocarbons, products are obtained which include numerous and peculiar cases of isomery. In the case of benzene itself there exist products of substitution con- taining 1, 2, 3, 4, 5, and 6 atoms of Cl, Br or I, or combinations of two or three of those elements. In the case of the unisubstituted derivatives, C6 HrCl, C6H6Br, and C,H.I, but one of each exists. Of the bisubstituted, trisubstituted, and quadrisubstituted derivatives three of each are known. From the existence of but one unisubstituted derivative it is obvious that it is immaterial in which of the CH groups this substitution occurs, and hence these six groups are equal to each other in value. The existence of isomeres of the higher products of substitution depends upon differences in the relative ‘positions of the substituted atoms to each other, their orien- tation as it is sometimes called, and not to their absolute positions. If we represent the molecule of benzene by a hexagon, leaving out the HALOID DERIVATIVES. 301 C and H symbols for the sake of brevity, we may start at any angle and number the angles corresponding to each C and H from one to six: /x\ 6 2 I i 5 3 In such a hexagon we may represent the formuhe of the three bisub- stituted Br derivates thus: Br I /K 6 2—Br I I 5 3 \4/ Br I /N 6 2 I I 5 3—Br \4/ Br /N 6 2 I I 5 3 \4/ I Br In No. 1 the positions of the substituted atoms are consecutive, and as the absolute positions in the molecule have no influence, it follows that 2—3 ; 3—4 ; 4—5 ; 5—6 ; 6—1, all are the same as 1—2. In number 2 the positions are unsymmetrical, or separated from each other by a sin- gle H atom ; and 2—4 ; 3—5 ; 4—6, and 5—1 are equal to 1—3. In number 3 the positions are symmetrical, or separated from each other by two H atoms ; and 2—5 ; 3—G ; 5—2, and 6—3, are the same as 1—4. From this it appears that but three bisubstituted Br products of benzene can exist. The three series of bi- and tri-substituted derivatives of benzene, whether the substitution be of a halogen or of any univalent element or radical, are designated by the prefixes ortho, meta, and para. Thus, in the figure above : 1. 2. 3. No. 1 = 1—2 = Ortliobibromo-benzene. No. 2 = 1—3 = Metabibromo-benzene. No. 3 = 1—4 = Parabibromo-benzene. The distinction between the three groups is best made by the relations between the bi- and tri-substituted derivatives. The consecutive or ortho bisubstituted derivatives can produce by further substitution two tri-de- rivatives ; the unsymmetrical, or meta, can produce three trisubstituted derivatives ; and the symmetrical, or para, can produce but one trisubsti- tuted derivative. In expressing the constitution of substituted derivatives it is customary either to use the prefixes ortho, para, and meta, as explained above, or to des- ignate the substance by the numerical positions of the substituted atoms or radicals, as in the following notices of the chlorine derivatives of benzene : Monochloro-benzene—C6H.C1—liquid ; boils at 132° (269°.6 F.) ; sp. gr. 1.128 at 0° ; obtained by the action of Cl upon C6H, in the cold, in the presence of a little I. Orthodichloro-benzene—1—2—liquid ; boils at 179° (354°.2); sp. gr. 1.328 at 0° ; obtained by the action of Cl on C6H6. Metadichloro-benzene—1—3—liquid ; boils at 172° (341°.6 F.); sp. gr. 1.307 at 0° ; obtainable indirectly. 302 MANUAL OF CHEMISTRY. Paradichloro-benzene—1—4—crystalline; fuses at 5G .4 (133 .5 F.); boils at 173° (343°.4 F.); is the principal product of the action of Cl on CbHf in presence of I. Trichloro-benzene—1—2—4—crystals ; fuses at 17' (G2°.G F.) ; boils at 213° (415°.4 F.). Trichloro-benzene—1—3—5—crystals; fuses at 63°.4 (14G°.1F.) ; boils at 208° (406°.4 F.). Tetrachloro-benzene—1—2—3—5—crystals; fuses at 50° (122“ I.); boils at 246° (474°.8 F.). Tetrachloro-benzene—1—2—4—5—crystals; fuses at 137 (2/8 .G I.); boils between 243°-24G° (4G9°.4-474°.8 F.). PHENOLS. The hydrocarbons of the benzene series, unlike those previously con- sidered, form two distinct kinds of hydrates, differing from each other materially in their properties. The terms of one of these series exhibit- all the functions of the alcohols, and are known as aromatic alcohols. The terms of the other series differ in function from any substance thus far considei’ed, and are known as phenols. The difference between them and the aromatic alcohols is due to the fact that in the phenols the OH is directly attached to a C atom, while in the alcohols it forms part of the group of atoms CH,OH, characteristic of the alcohols : H A H—C C-CH, I II H-C 0—OH \c/ I H H I H— C C—CH2OH I II H—C C-H \c/ | H Benzylic alcohol. The phenols differ from the alcohols in not furnishing by oxidation corresponding aldehydes and acids ; in not dividing into water and hydro- carbon under the influence of dehydrating agents ; in not reacting with acids to form ethers ; in combining to form directly products of substitu- tion with Cl and Br ; and in forming with metallic elements compounds more stable than similar compounds of the true alcohols. In short, the phenols appear to have, besides an alcoholic function, more or less of the function of acids. Phenol—Phenyl hydrate—Phenic acid—Carbolic acid—Acidum carboli- cum (U. S., Br.)—C, H OH—94—exists in considerable quantity in coal- and wood-tar, and in small quantity in castoreum, and possibly in urine. It is formed : (1) by fusing sodium phenylsulpliide with an excess of alkali; (2) by heating phenyl iodide with potassium hydrate to 320° (608° F.) ; (3) by heating together salicylic acid and quicklime ; (4) by total synthesis from acetylene ; (5) by dry distillation of benzoin. The source from which it is obtained is that portion of the product of distillation of coal-tar which passes over between 150° and 200° (302°- 392° F.). This is treated with a saturated solution of potash, containing undissolved alkali; a solid plienate is formed, which is dissolved in hot H,0 ; the liquid is allowed to separate into two layers, the lower of which Benzylic Thenol. PHENOL. 303 is drawn off and neutralized with HC1; the phenol rises to the surface, is separated, washed with water, dried over calcium chloride, redistilled, crystallized at —10° (14° F.), and the crystals drained. Pure phenol crystallizes in long, colorless, prismatic needles, fusible at 35° (95° F.), boiling at 187° (368°.6 F.). It has a peculiar, well-known odor, and an acrid, burning taste ; very sparingly soluble in water, readily soluble in alcohol and in ether; sp. gr. 1.0G5 at 18° (64°.4 F.) ; neutral in reaction. On contact with the skin or with mucous surfaces, it produces a white stain ; it coagulates albuminoids, and is a powerful antiseptic. It may be distilled without decomposition. It absorbs H„0 from damp air to form a hydrate, which crystallizes in six-sided prisms, fusible at 1G° (60°.8 F.). Its vapor is reduced to benzene when heated with Zn. It combines with H.,S04 to form phenylsxdphuric acids. It forms trinitro- phenic acid (q. v.) with HNO? of 36° B. When heated with H.,S04 and oxalic acid it forms rosolic acid or corallin, which is a mixture from which the pigments aurin, peonin, azulin, and phenicin are obtained. Analytical Characters.—(1.) Its peculiar odor. (2.) Mix with one-quarter volume of NH,HO ; add two drops sodium hypochlorite solution, and warm ; a blue or green color. Add HC1 to acid reaction ; turns red. (3.) Add two drops of liquid to a little HC1, add one drop HN03 ; a purple red color. (4.) Boil with HNO.( as long as red fumes are given off. Neutralize with KHO ; a yellow, crystalline precipitate. (5.) With FeS04 solution ; a lilac color. (6.) Float the liquid on H,S04, add powdered IyX03; violet color. (7.) With excess of Br water ; a yellowish-white precipitate. Toxicology.—When taken internally, phenol is an active poison, and one whose use by suicides has become quite common. W hen it has been taken the mouth is whitened by its caustic action, and there is a marked odor of carbolic acid in the breath. It is eliminated by the urine, partly unchanged, and partly in the form of colored derivatives, which color the urine greenish, brownish, or even black. The treatment consists in the administration of albumen (white of egg) and of emetics. To detect phenol in the urine, that liquor must not be distilled with H,S04, as sometimes recommended, as it contains normally substances which by such treatment yield carbolic acid. The best method consists in adding an excess of bromine water to about 500 c.c. (1 pint) of the urine ; on standing some hours, a yellowish precipitate collects at the bottom of the vessel; this is removed, washed, and treated with sodium amalgam, when the characteristic odor of phenol is developed. From other parts of the body, phenol may be recovered by acidulating with tartaric acid ; dis- tilling ; extracting the distillate by shaking with ether; evaporating the ethereal solution ; extracting the residue with a small quantity of water, and applying to this solution the tests described above. Cresylol—Gresol—Cresylic acid—Benzylic phenol—Cresylic phenol— C H (CHJOH —108—accompanies phenol in coal- and wood-tars, from which it may be obtained by fractional distillation ; it is more readily obtained pure from toluene. When pure it is a crystalline solid, fusible at 34".5 (94 .1 F.); as usually met with, however, it is a liquid, which does not solidify at 18 ( —0°.4 F.), and boils at 203° (397°.4 F.) ; it has an odor of creasote. Its properties, decompositions, and products resemble those of phenol. Creasote—Creasotum (U. S.).—is a complex mixture, containing phenol, cresylol, creasol, CtH10O2, and other substances, obtained from wood-tar, 304 MANUAL OF CHEMISTRY. and formerly extensively used as an antiseptic. It is an oily liquid, color- less when freshly prepared, but becoming brownish on exposure to light; it has a burning taste and a strong, peculiar odor ; it boils at 203° (397°.4 F.), and does not solidify at —27° ( —16°.G F.). Crude phenol is often substituted for creasote ; the two substances may be distinguished by the following characters : Phenol. Creasote. Soluble in commercial glycerin. Precipitates nitro-cellulose from collodion. Gives a brown color with ferric chloride and alcohol Gives a violet color with ferric chloride and ammonium hydrate. Insoluble in commercial glycerin. Does not precipitate collodion. Gives a green color with ferric chloride and alcohol. Gives a green color, passing to brown, with ferric chloride and ammonium hydrate. Xenols—Xylenols—CfH3(CH. )2OH—122.—Theoretically there are six possible xenols derivable from corresponding xylenes ; of these, four have been thus far obtained by the general methods of obtaining the phenols. None is of practical interest. Thymol— Cymylic phenol—C6H(CHs)4OH— 150—exists, accompany- ing cymene and thymene, C10HJ0, in essence of thyme, from which it is ob- tained. The essence contains about one-half its weight of thymol, which is separated by agitation with a concentrated solution of caustic soda ; separation of the alkaline liquid, which is diluted and neutralized with HC1; thymol separates and is purified by rectification at 230° (446° F.). It crystallizes in large, transparent, rliombohedral tables ; has a pep- pery taste and an agreeable, aromatic odor; it fuses at 44° (111°.2 F.), and boils at 230° (446° F.) ; is sparingly soluble in water, very soluble in alcohol and ether; with the alkalies it forms definite compounds, which are very soluble in water. Its reactions are very similar to those of phenol. Thymol is an excellent disinfecting and antiseptic agent, and oue of the best of embalming materials ; possessing the advantage over phenol of having itself a pleasant odor. SUBSTITUTED PHENOLS. We have seen above (p. 301) how three bi- and tri-substituted deriva- tives are derivable from benzene. Phenol is a unisubstituted derivative of the same substance and hence still contains five H atoms which may be replaced by other elements or radicals. So long as but one other univalent atom or radical is introduced, the number of possible derivatives remains the same as if but one kind of atom or radical were introduced, as the reversal of the order Cl Br or Br Cl cannot influence the nature of the compound. But when the number of substituted atoms, differing in kind, is increased beyond two, or the valence of one or more of them exceeds one, the num- ber of possible isomeres is progressively increased. Thus, while there are but three tribromo-benzenes: Br Br Br .1 I I / 1 \ / 1 \ / 1 \ 6 2—Br 6 2 6 2 II II I > I 5 3—Br 5 3—Br Br—5 3—Br \ 4 / \ 4 / \ 4 / ! Br 305 SUBSTITUTED PHENOLS. there are six chlorobromo-benzenes : Br I /K 6 2—Br I I 5 3—Cl \4/ Br I /K 6 2—Br I I 5 3 I Cl Br /N 6 2—Cl I I 5 3—Br / 1. 2. 3. Br I /K 6 2 I I 5 3—Br \4/ I Cl Br I /N 6 2 I I Cl—5 3—Br Br I /K 6 2 I I 5 3—Cl w I Br 4. 5. 6. of which 1 and 2 are derivable from orthobibromobenzene (see p. 301); 3 4, and 5 from metabibromobenzene, and 6 from parabibromobenzene. If, in place of two elements or radicals, we have three, the number of tri- substituted derivatives is increased to ten. In the place of Cl and Br in the above examples any univalent atom or radical may be substituted, thus giving rise to a great number of deriva- tives. Certain of such substituted radicals determine the function of the original unisubstituted derivative of benzene and of all of its polysubstituted derivatives. Thus the group (OH) is characteristic of the phenols ; (CH.J or (C,.H8)l +1) of the superior homologues of benzene ; (CH2OH) of the alcohols; (COOH) of the acids ; (NO.,) of the nitro-derivatives ; (NH,,) of the amines, etc. The naming of such polysubstituted derivatives presents many diffi- culties. Adherence to the principle that the name of a compound shall indicate its constitution, involves the construction of names which are fre- cjuently of unwieldy length. It is usual to consider the characterizing group as occupying the position 1 in the hexagon, and to prefix the term ortho to the name of that radical or atom occupying one of the ortho-posi- tions 2 and 6 with relation to the characterizing group ; meta to that occupying one of the meta-positions 3 and 5; and para to that occupying the para-position 4. Thus the substance having the constitution indicated by the formula 1 (see next page) is designated by the name orthonitroparabromo-phenol. But even this is not always sufficiently definite, for to each of the substances 2 and 3 (see next page), although differing in characters, the name or- thonitrometabromo-phenol applies. It has been suggested, to avoid this difficulty, that the prefix allortho be used to designate the second or- 306 MANUAL OF CHEMISTRY. tho-position G, and the prefix allometa to designate the second meta-posi- tion 5. OH I /K 6 2—(NOa) I I 5 3 I Br. OH /K 6 2—(NOs) I I 5 3—Br \4/ OH I (NO,)—6 2 I I 5 3— Br \4/ 1. 2. 3. The name of No. 3 would thus become metabromoallorthonitro-phenol. When formulae are used, all confusion. may be readily avoided, even in the most complex substances, by the use of the numeral corresponding to the position in the benzene chain, enclosed in brackets. Thus, the for- mulae of 2 and 3 above may be written : C0H,(OH)(NO,)<,,Br(,>; and C.H,(OH)Br(^NO,)(.). Nitro-phenols—Mononitro-phenols — C6H4(NOa)OH—(1—2), (1—3), and (1—4) are formed by tlie action of HN03 on CgHBOH. The ortho com- pound (1—2) crystallizes in large yellow needles, sparingly soluble, and capable of distillation with steam. The meta and para compounds are both colorless, non-volatile, crystalline bodies. Two dinitro-phenols, C6H3 OH(NOa)a (2_4) and C6H30H(N0.2)a(a_6) are obtained by the action of strong nitric acid on phenol, or on ortho- or para-mononitro-phenol. They are both solid, crystalline substances, converted by further nitration into pic- ric acid. Trinitro-phenols—C#IJ2(NOa)3OH. Two are known. (1.) Picric acid—■ Carbazotic acid—Trinitro-phenic acid—(NO.,) in 2—4—6. It is formed by nitrification of phenol, or of 1—2:—4 or 1—2—G dinitro-phenols, and also by the action of HN03 on indigo, silk, wool, resins, etc. It crystallizes in brilliant, yellow, rectangular plates, or in six-sided prisms ; it is odorless, and has an intensely bitter taste, whence its name (from -i/cpos =bitter); it is acid in reaction ; sparingly soluble in water, very soluble in alcohol, ether, and benzene ; it fuses at 122°.5 (252°.5F.), and may, if heated with cau- tion, be sublimed unchanged ; but, if heated suddenly or in quantity, it explodes with violence. It behaves as a monobasic acid, forming salts, which are for the most part soluble, yellow, crystalline, and decomposed with explosion when heated. Picric acid is valuable as a dye-stuff, coloring silk and wool yellow ; as a staining medium in histological investigations ; and as a reagent for the alkaloids, with many of which it forms crystalline precipitates. It is also sometimes fraudulently added to beer and to other food articles, to communicate to them either a bitter taste or a yellow color. Analytical Characters.—(1.) Its intensely bitter taste. (2.) Its alcoholic solution, when shaken with a potassium salt, gives a yellow crystalline ppt. DIATOMIC PHENOLS 307 (3.) An ammoniacal solution of cupric sulphate gives a green, crystal- line ppt. (4.) Glucose, heated with a dilute alkaline solution of picric acid, com- municates to it a blood-red color. (5.) Warmed with an alkaline solution of potassium cyanide, an in- tense red color is produced (the same effect is produced by ammonium sulphydrate). (6.) Unbleached wool, immersed in boiling solution of picric acid, is dyed yellow. Nos. 1, 3, 5, and 6 are quite delicate. When taken internally in overdose, it acts as a poison ; it may be separated from animal fluids or from beer by evaporation to a syrup, ex- tracting with 95 per cent, alcohol, acidulated with H.,S04; filtering; evaporating ; and applying the tests to a solution of the residue. DIATOMIC PHENOLS. Diatomic phenols are derived from the benzene series of hydrocarbons by the substitution of two (OH) groups for two atoms of hydrogen. In obedience to the laws of substitution already discussed, three such com- pounds exist, corresponding to each hydrocarbon. Thus, in the case of benzene : OH I 1 /\ 6 2—OH I I 5 3 \/ 4 OH i 6/X2 I I 5 3—OH \/ 4 OH I i i v o'h Ortho. 1—2 Pyrocatechin. Meta. 1-3 Resorcin. Para. 1—4 Hydroquinone. Pyrocatechin—Oxyphenic acid—Orthodioxy-benzene—CfH(OH),— 1—2—is obtained from catechin or from morintannic acid by dry distilla- tion ; also by the action of KHO on orthochlor- or ortlioiodo-phenol, or by decomposing its methyl ether, guaiacol, by HI at 200° (392° F.). It crystal- lizes in short, square prisms ; fuses at 104° (219°.2 F.), and boils at 245°.5 (473°.9 F.). Readily soluble in water, alcohol, and ether. Its aqueous solution gives a dark-green color with Fe .Cl,. solution, changing to violet on addition of NH4HO, NaHC03, or tartaric acid. Resorcin—Metadioxy--benzene—CrH (OH)3—1—3—is obtained by the action of fused KHO on parachlor- or iodo-plienol. It is usually prepared by dry distillation of extract of Brazil wood. It forms short, thick, colorless and odorless, rhombic prisms. Fuses at 104° (219°.2 F.), and boils at 271° (519°.8 F.). It is very soluble in water, alcohol, and ether. Its aqueous solution is neutral in reaction, and intensely sweet. With FenCl,. its solutions assume a dark-violet color, which is discharged by NH4HO. Its ammoniacal solution, by exposure to ah’, assumes a pink color, changing to brown and, on evaporation, green 308 MANUAL OF CHEMISTRY. and dark blue. Heated with phthalic anhydride at 195° (383° F.) it yields fluorescein (see page 309). It dissolves in fuming HoS0., forming an orange-red solution, which becomes darker and then changes to green- ish-black and then pure blue, and to purple on being warmed. Resorcin has been recently used in medical practice. Hydroquinone—Paradioxy-benzene—CcH (OH)2—1—4—is formed by fusing paraiodo-phenol with KHO at 180° (356° F.), by dry distillation of oxysalicylic acid or of quinic acid, and by the action of reducing agents on quinone. It forms colorless, rhombic prisms, which fuse at 169° (336°.2 F.). Readily soluble in water, alcohol, or ether. Its aqueous solution is turned red-brown by NH4HO. Oxidizing agents convert it into quinone. Quinone— '—is the representative of a number of similar compounds, derivable from the aromatic hydrocarbons. It is produced by the oxidizing action of MnO„ + H2S04, or of dilute chromic acid, upon quite a number of para-benzene derivatives ; but best by the limited oxida- tion of quinic acid. It crystallizes in yellow prisms; fuses at 116° (240°.8 F.); sublimes at ordinary temperatures; is sparingly soluble in cold, but readily soluble in hot water and in alcohol or ether. It gives off a peculiar pungent odor and stimulates the lachrymal secretion. Reducing agents convert it into hydroquinone. There is no similar substance known corresponding either to pyro- catechin or to resorcin. Orsin—Dimetadioxy-toluene — CfH3 (CH3)(l)(OH)(3)(OH) (ft) — exists in nature in those lichens which are used as sources of archil and litmus (Rocella tinctoria, etc.). It crystallizes in six-sided prisms ; is sweet; read- ily soluble in water, alcohol, or ether ; fuses at 58° (136°.4 F.). Its aqueous solution is colored violet-blue by Fe2Cl6. It unites with XH3 to form a compound which absorbs O from the air and is converted into orcein, C.H.NO, ; a dark red or purple body, which is the chief constituent of the dye-stuff known as archil, cudbear, French purple, and litmus. TRIATOMIC PHENOLS. The only compounds of this class at present known with certainty are two isomeric triatomic phenols, which owe the differences in properties existing between them to a different placing of the OH groups. They are phloroglilcin and pyrogallol. Phloroglucin—C5H3(OH) 3—126—is obtained by the action of potash upon phloretin, quercitrin, maclurin (see Glucosides), catechin, kino, etc. It crystallizes in rhombic prisms, containing 2 Aq; is very sweet; very soluble in water, alcohol, and ether. Pyrogallol—Pyrogallic acid—C(.Ha(OH)s—126—is formed when gal- lic acid (q. v.) is heated to 200° (392° F.). It crystallizes in white nee- dles ; neutral in reaction ; very soluble in water ; very bitter; fuses at 115° (239° F.); boils at 210° (410° F.) ; poisonous. Its most valuable property is that of absorbing oxygen, for which purpose it is used in the laboratory in the form of a solution of potassium pyrogallate. AROMATIC ALCOHOLS PHENOL DYES. Aurin—C10H14O3 and Rosolio acid—C , Hl t.03—are substances ex- isting in the dye obtained by the action of oxalic acid upon phenol in presence of H„S04, known as coralline or pceonine, which communicates to silk or wool a fine yellow-red color. Aurin crystallizes in fine, red needles from its solution in HC1. It is insoluble in H.O, but soluble in HC1, alcohol, and glacial acetic acid. It forms a colorless compound with potassium bisulphite. Phthaleins.—These substances are produced by heating the phenols with phthalic anhydride, ChH403, water being at the same time eliminated. Their constitution is that of a benzene nucleus, two of whose H atoms have been replaced by two acetone groups (CO), whose remaining valences attaches them to two phenol groups by exchange with an atom of hy- drogen. Thus Phenol-phthalein, the simplest of the group, has the constitution / CO—CcH4(OH). CrH, Phenol-phthalein is a yellow, crystalline powder, \CO-CfH4(OH). insoluble in water, but soluble in alcohol. Its alcoholic solution, perfectly colorless if neutral, assumes a brilliant magenta-red in the presence of an alkali. This property renders phenol-phthalein very valuable as an in- dicator of reaction. Resorein-phthalein—Fluorescein—C„„H1;!05—bears the same rela- tion to resorcin that phenol-phthalein does to phenol, and is obtained from resorcin by a corresponding method. It is a dark-brown crystalline powder, which dissolves in ammonia to form a red solution, exhibiting the most brilliant green fluorescence. A tetrabromo-derivative of fluorescein is used as a dye under the name eosin. AROMATIC ALCOHOLS. The alcohols corresponding to this series of hydrocarbons have the same composition as the corresponding phenols, from which they differ in con- stitution and in having the functions of true alcohols. They yield on oxidation, first an aldehyde and then an acid, and they contain the char- acterizing group of the primary alcohols, CH„OH ; once if the alcohol be monoatomic, twice if diatomic, etc. Thus : C6H5,CH„OH = Benzylic alcohol. C,.H.,COH = Benzoic aldehyde. C(.H ,COOH = Benzoic acid. As they contain the benzene nucleus they are capable of yielding isomeric products of further substitution, ortho, para, or meta, according to the position of the substituted atom or radical. Benzylic alcohol—Benzoic alcohol—Benzyl hydrate—CH5(CH,OH) —108—does not exist in nature, and is of interest chiefly as correspond- ing to two important compounds, benzoic acid and benzoic aldehyde (oil of bitter almonds). It is obtained by the action of potassium hydrate upon oil of bitter almonds, or by slowly adding sodium amalgam to a boiling solution of benzoic acid. 310 MANUAL OF CHEMISTRY. It is a colorless liquid ; boils at 206°.5 (403°.7 F.); has an aromatic odor; is insoluble in water, soluble in all proportions in alcohol, ether, and carbon disulphide. By oxidation it yields, first, benzoic aldehyde, CfH.(COH); and afterward, benzoic acid, C,Hr(COOH). By the same means it may be made to yield products similar to those obtained from the alcohols of the saturated hydrocarbons. ALPHENOLS. These substances are intermediate in function between the alcohols and the phenols, and contain both substituted groups (OH) and CH.OH. / CH„OH Saligenin, CrH4 —124—is obtained from salicin (y. v.) in \OH large, tabular crystals ; quite soluble in alcohol, water, and ether. Oxi- dizing agents convert it into salicylic aldehyde, which by further oxidation yields salicylic acid. It is also formed by the action of nascent hydrogen on salicylic aldehyde. ALDEHYDES Benzoic aldehyde—Benzoyl hydride—C6Hr (COH)—10G—is the main constituent of oil of bitter almonds, although it does not exist in the almonds (see p. 829) ; it is formed, along with hydrocyanic acid and glu- cose, by the action of water upon amygdalin. It is also formed by a num- ber of general methods of producing aldehydes: by the dehydration of benzylic alcohol; by the dry distillation of a mixture in molecular pro- portions of calcium benzoate and formiate ; by the action of nascent hydrogen upon benzoyl cyanide, etc. It is obtained from bitter almonds. The crude oil contains, besides benzoic aldehyde, hydrocyanic and benzoic acids and cvanobenzoyl ; to purify it, it is treated with three to four times its volume of a concen- trated solution of sodium bisulphite ; the crystalline mass is expressed, dissolved in a small quantity of water, and decomposed with a concen- trated solution of sodium carbonate—the treatment being repeated, if necessary. It is a colorless oil, having an acrid taste and the odor of bitter almonds; sp. gr. 1.043 ; boils at 179°.4 (354°.9 F.) ; soluble in 30 parts of water, and in all proportions in alcohol and ether. Oxidizing agents convert it into benzoic acid, a change which occurs by mere exposure to air. Nascent hydrogen converts it into benzylic alcohol. With Cl and Br it forms benzoyl chloride or bromide. H.,S04 dissolves it when heated, forming a purple-red color, which turns black if more strongly heated. When perfectly pure, benzoic aldehyde exerts no deleterious action when taken internally ; owing, however, to the difficulty of completely removing the hydrocyanic acid, the substances usually sold as oil of bitter almonds, ratafia, and almond flavor, are almost always poisonous, if taken in sufficient quantity. They may contain as much as 10-15 per cent, of hydrocyanic acid, although said to be “purified.” The presence of the poisonous substances may be detected by the tests given on page 327. Salicylic aldehyde—Salicyl hydride—Salicylol—Salicylous acid— C5H4 (OH) COH—122—exists in the flowers of spiraea ulmaria, and is the 311 AROMATIC ACIDS. principal ingredient of the essential oil of that plant. It is best obtained by oxidizing salicin (q. u). It is a colorless oil; turns red on exposure to air ; has an agreeable, aro- matic odor, and a sharp, burning taste ; sp. gr. 1.173 at 13°.5 (56°.3F.) ; boils at 196°.5 (385°.7 F.) ; soluble in water, more so in alcohol and ether. It is, as we should suspect from its origin, a substance of mixed func- tion, possessing the characteristic properties of aldehyde and phenol. It produces a great number of derivatives, some of which have the charac- ters of salts and ethers. Methyl-protocatechuic aldehyde— Vanillin — C6H3(OH)(OCH3) COH—is the odoriferous principle of vanilla. It is produced artificially by oxidation of coniferin, C18H2208, a glucoside occurring in coniferous plants. It crystallizes in needles, fuses at 80° (176° F.) ; is sparingly sol- uble in water, readily soluble in alcohol or ether. It has a pungent taste, and a faint odor of vanilla, the latter more marked when the substance is heated. On exposure to air it becomes partially oxidized to vanillic acid, CsHfl04. ACIDS CORRESPONDING TO THE AROMATIC HYDRATES The acids, possibly derivable from benzene by the substitution of (COOH), or of (COOH) and (OH), for atoms of hydrogen, would form, were they all known, a great number of series; there are, however, compar- atively few of them which have been as yet obtained, although the num- ber of acid series known is greater than that of corresponding alcohols. Each series of mono- and diatomic alcohols furnishes a corresponding series of acids ; thus : C6H5-CH2OH ch/CH2OH ‘\CH2OH c ii /ch,oh ■•'-OH. Benzoic alcohol. Toluyl glycol. Saligenin. C6Hs-COOH r Tr /COOH n4\cOOH r Ty /COOH Benzoic acid. Terephthalic acid. Salicylic acid. There are still a number of other series of acids possibly derivable directly from benzene, without speaking of substituted acids of more com- plex nature ; of these, however, the majority are wanting. By the progressive substitution of groups (COOH) for atoms of hydro- gen in benzene, we may obtain six series of acids, five of which have been isolated: C,.H5(COOH) — CnH2„_ 802 Benzoic series. Ct.H4(COOH)2 —CnH.2„_10O4 Phthalic series. C,H3(COOH)3 —CnH,„_12Or) Trimellitic series. C6H2(COOH)4— C„H2n_14Og Prebnitic series. CpH(COOH)5 —C„H2n_1#O10 Wanting. C6(COOH)8 —CnH2n_ie012 Mellitic series. The alphenols, containing a single group (OH), are at present repre- sented by a single series: C6H4(OH)(COOH)—CnII2n_,03—Salicylic series. 312 MANUAL OF CHEMISTRY. Corresponding to the unknown alplienols, containing a greater number of (OH) groups, there are at present but two series of acids knowu : CcH3(OH)2(COOH)—CnH2„_B04—Veratric series, and C6H2(OH)3(COOH)—CkH „_806—Gallic series. In each of these series the basicity is, as usual, equal to the number of groups (COOH). Benzoic acid — Acidum benzoicum (U. S.)— CfH (COOH)—122— exists ready formed in benzoin, tolu balsam, castoreum, and several resins, It does not exist in animal nature, so far as is at present known ; in those situations in which it has been found, it has resulted from decomposition of hippuric acid (q. v.), or has been introduced from without. When taken in moderate doses, it does not pass out in its own form, but is con- verted into hippuric acid ; in excessive doses a portion is eliminated un- changed in the urine. It is obtained from benzoin, or from the urine of herbivorous animals ; and is formed in a variety of reactions. It crystallizes in white, transparent plates ; odorless ; acid ; fuses at 122° (251°.6 F.); sublimes at 145° (293° F.); boils at 240° (464° F.); spar- ingly soluble in cold water ; soluble in hot water, alcohol, and ether. Dilute HNO does not attack it. It dissolves in ordinary H2S04, and is precipitated unchanged by H20. Its salts are all soluble. Hippuric acid-Benzyl-glycocol—Benzyl-amido-acetic acid—C.H NO. —179—is a constant constituent of the urine of the herbivora, and of human urine to the extent of 0.29-2.84 grams (4.5-43.8 grains) in 24 hours. It is more abundant with a purely vegetable diet, after the ad- ministration of benzoic acid, and in diabetes mellitus and chorea. It crystallizes in transparent, colorless, odorless, bitter prisms ; spar- ingly soluble in water; fuses at 130° (266° F.). It dissolves unchanged in HC1; but on boiling the solution it is decomposed into benzoic acid and glycocol. The same decomposition is effected by dilute H2SO., HNOa, and oxalic acid, and by a ferment developed in putrefying urine. Oxidizing agents convert it into benzoic acid, benzamide, and CO„. The characters of hippuric acid are : (1) when heated in a dry tube it fuses and gives off a sublimate of benzoic acid and an odor of hydrocyanic acid ; (2) it gives a brown ppt. with ferric chloride ; (3) when heated with lime it gives off benzine and ammonia. Salicylic Acid—Oxybenzoic acid—Acidum salicylicum (U. S.)—C6H4 (OH) COOH —138—was first obtained from essence of spiraea, which con- sists largely of salicylic aldehyde, and subsequently from oil of winter- green (gaultheria), which contains methyl salicylate ; and also from salicin, a glucoside yielding salicylic aldehyde. It is now obtained from phenol. This is fused, and, while a cun*ent of dry CO„ is passed through it, small portions of Na are added ; the sodium salicylate thus formed is dissolved in H.,0 and decomposed with HC1, when the liberated salicylic acid is precipitated. It crystallizes in fine white needles ; very sparingly soluble in cold water, quite soluble in hot water, alcohol, and ether; it fuses at 158° (316°.4 F.), and may be distilled with but slight decomposition, if it be pure. Cl and Br form with it products of substitution. Fuming HN03 forms with it a nitro-derivative and, if the action be prolonged, converts it into picric acid. With ferric chloride, its aqueous solution assumes a fine violet color. AM1DO-DER1VATIVES. 313 Salicylic acid and its salts (it is monobasic, although diatomic) are extensively used in medicine, both externally as antiseptics and internally in the treatment of rheumatism, etc. It is not without caustic properties, and hence, when taken internally, it should be largely diluted. Gallic acid—Acidum gallicum (U. S.)—C#H2(OH)3COOH—170— exists in nature in certain leaves, seeds, and fruits. It is best obtained from gall-nuts, which contain its glucoside, gallotannic acid (q. v.). It can be obtained from salicylic acid. It crystallizes in long silky needles with 1 Aq ; odorless ; acidulous in taste ; sparingly soluble in cold water, very soluble in hot water and in alcohol; its solutions are acid. When heated to 210 -215° (410 -419° F.) it yields C02 and pyrogallol (q. v.). Its solution does not precipitate gelatin, nor the salts of the alkaloids, as does tannin. It forms four series of salts. NITRO-DERIVATIVES OF BENZENE. By substitution of the univalent radical (NOs) for the hydrogen of ben- zene a series of substitution products are obtainable, corresponding to the series of haloid derivatives, phenols, etc. (see pp. 301, 304, 305). Nitro-benzol—Nitro-benzene—Mono-nitro-benzene—Essence of Mir- bane—C, H (NO.,)—123—is obtained by the moderated action of fuming HNOa, or of a mixture of HX03 and H2SO„ on benzene. It is a yellow, sweet liquid, with an odor of bitter almonds ; sp. gr. 1.209 at 15° (59° F.); boils at 213° (415°.4 F.); almost insoluble in water ; very soluble in alcohol and ether. Concentrated H S04 dissolves, and, when boiling, decomposes it. Boiled with fuming HXO,., it is converted into binitro-benzol. It is converted into aniline by reducing agents. It has been used in perfumery as artificial essence of bitter almonds ; but as inhalation of its vapor, even largely diluted with air, causes headache, drowsiness, difficulty of respiration, cardiac irregularity, loss of muscular power, convulsions, and coma, its use for that purpose is to be condemned. Taken internally it is an active poison. Nitro-benzol may be distinguished from oil of bitter almonds (benzoic aldehyde) by HoS04, which does not color the former ; and by the action of acetic acid and iron filings, which convert nitro-benzol into aniline, whose presence is detected by the reactions for that substance (q. v.). AMIDO-DERIVATTVES OF BENZENE. These substances are derivable from benzene and its homologues by the substitution of one or more univalent groups (NH„) (amidogen) for atoms of hydrogen. They may also be considered as pheuylamines, pro- duced by the substitution of the univalent radical phenyl (C6H5), or its homologues, derivable from the benzene nucleus, for the hydrogen of ammonia. They all are strongly basic in character. Aniline — Amido-benzene — Amido-benzol — Phenylamine — Kyanol — f1 H ) Crystalline— j- N—93—exists in small quantity in coal-tar and is one of the products of the destructive distillation of indigo. It is prepared by the reduction of nitro-benzene by hydrogen : C,.H:(NO.,) + 3H, = CfH5 (NH„) + 2H,0 ; the hydrogen being liberated in the nascent state in con- tact with nitro-benzol by the action of iron filings on acetic acid. 314 MANUAL OF CHEMISTRY. Pure aniline is a colorless liquid ; has a peculiar, aromatic odor, and an acrid, burning taste ; sp. gr. 1.02 at 16° (60°.8 F.); boils at 184°.8 (364°.6 F.) ; crystallizes at —8° (17°.6 F.); soluble in 31 pts. of cold water, soluble in all proportions in alcohol, ether, carbon disulphide, etc.; when exposed to air, it turns brown, the color of the commercial “oil,” and, finally, resini- fies; it is neutral in reaction. Oxidizing agents convert it into blue, violet, red, green, or black derivatives. Cl, Br, and I act upon it violently to produce products of substitution. Concentrated H2S04 converts it accord- ing to the conditions, into sulphanilic or disulphanilic acid. With acids it unites, after the manner of the ammonia, without liberation of H20 or H to form salts, most of which are crystallizable, soluble in water, and colorless, although by exposure to air, especially if moist, they turn red. Analytical Characters.—(1.) With a nitrate and H.,S04, a red color. (2.) Cold H2S04 does not color it alone ; on addition of potassium di- cliromate, a fine blue color is produced, which, on dilution with water, passes to violet, and, if not diluted, to black. (3.) With calcium hypochlorite, a violet color. (4.) Heated with cupric chlorate, a black color. (5.) Heated with mercuric chloride, a deep crimson color. Toxicology.—Aniline itself, when taken in the liquid form or by inhala- tion, is an active poison, producing symptoms similar to those caused by nitro-benzol (q. v.). Its salts, if pure, seem to have but slight deleterious action. DERIVATIVES OF ANILINE By the substitution of other radicals or elements for the remaining hy- drogen atoms of the benzene nucleus, or for the hydrogen atoms of the amidogen group, NH2, a great number of derivatives, including many iso- meres, are produced. In all of these derivatives the group (NH„) is considered as occupying the position 1. Chloranilines.—Three monochloranilines are known, of which two, ortho- (1—2) and meta- (1—3), are liquid. The other, para- (1—4), is solid and crystalline. Four dichloranilines, 1—2—4, 1—2—5, 1—3—5, and 1—3—4, are known, all solid and crystalline. Two trichloranilines, 1—2—4—6 and 1—2—4—5 are known, both solid and crystalline. The corresponding bromanilmes are also known ; also a tetrabromaniline, 1—2—3—4—6, and a pentabromaniline, C6(NH2)Br6. Of the possible iodanilines, but four have been described : Metamono- iodaniline (1—3); paramoniodaniline (1—4); the diiodaniline (1—2—4); and the triiodaniline (1—2—4—6). Nitranilines.—The three isomeres, ortho-, meta-, and para- Mononi- tranilines, CGH4(NH2)(N02) are formed by imperfect reduction of the di- nitro-benzenes. Two dinitranilines, CrH3(NH„)(N02)2 (1—2—4) and (1—2—6), are known. A single trinitraniline, CGH2(NH2)(N02)3 (1—2—4—6), has been ob- tained by the action of alcoholic ammonia upon the etliylic or methylic ether of picric acid. It is also called picramide. Anilides.—These are compounds in which one of the H atoms of the amidogen group has been replaced by an acid radical. Or they may also ANILINE DYES. 315 be considered as amides, whose remaining hydrogen has been more or less replaced by phenyl, C,Hr. Acetanilide—C,H.(NH.C„H.jO) = Phenyl-acetamide—is obtained either by heating together aniline and glacial acetic acid for several hours, or, better, by the action of acetyl chloride on aniline. It forms colorless, shining, crystalline scales; fuses at 112°.5 (234°.5 F.), and volatilizes un- changed at 295° (563° F.). It is sparingly soluble in cold water, soluble in hot water and in alcohol. It has been recently introduced into medical practice as an antiperiodic, under the name antifebrine. ANILINE DYES. It was observed at an early period that when crude aniline was acted upon by oxidizing agents a brilliant red color was produced. Efforts to isolate this color, beginning in 1856, have led, not only to success in the end de- sired, but also to the discovery of a great number of substances, many of which are valuable as dye-stuffs communicating not only brilliant colors, but the greatest variety of shades and colors. Among the substances com- mercially classified as aniline dyes are many pigments which do not prop- erly belong here, being derivatives of phenol, naphthalene, anthracene, etc. Of the true aniline dyes the most important, and that from which most of the others are industrially derived, is fuchsine, also called magenta, ani- line red, roseine, azaleine, etc. Although fuchsine is obtainable by a great variety of methods, those industrially used are limited to modifications of two: the oxidation of commercial aniline by arsenic acid, or by a mixture of nitro-benzene, hy- drochloric acid, and iron filings; and the purification of the product, after combination with an acid, by repeated recrystallizations. The commercial fuchsine, which varies much in quality, is a hard, more or less crystalline substance of a brilliant green color, sparingly soluble in cold water, readily soluble in hot water and in alcohol, the solutions having a brilliant red color. The commercial fuclisines are salts, usually the chloride or acetate, of a base which is itself colorless, called rosaniline, whose constitution has been but recently determined, having the empirical formula C20H19N3,H2O. Rosaniline is one of a series of homologous substances the first term of which is pararosaniline, C19H10N3O—whose molecule : H H /5\ /3x XH—4 6—H H—2 4—NH, H—3 1 alt 1 5—H N/\T /n/ XC 7 I H lx H H—6 2—H I I H—5 3—H \4/ I NH„ 316 MANUAL OF CHEMISTRY. consists of three benzene nuclei, united bj’ a group (COH), the para H atom of each of the benzene nuclei being replaced bv a group (NH2). The remaining H atoms of the benzene nuclei may be replaced, either by CH., to produce the higher homologues, or by other atoms or radicals. Neither pure aniline nor pure toluidine will produce a red color by the action of oxidizing agents, the formation of a rosaniline requiring a combination of the two. The rosanilines are powerful triacid bases, forming salts which are all colored, and from whicli the colorless bases may be separated by decom- posing concentrated solutions of their salts with concentrated KHO solu- tion. Hoffman's violet is triethyl-rosaniline chloride, produced by heating to- gether ethyl iodide and rosaniline. Lyons blue = triphenyl-rosaniline chloride, obtained by heating rosaniline with an excess of aniline ; yas green, obtained by heating rosaniline chlo- ride with aldehyde and sulphuric acid ; Paris violet, obtained by the oxida- tion of methyl aniline. Mauvein is a base whose sulphate, obtained by mixing cold dilute solu- tions of potassium dichromate and aniline sulphate, is a fine, purple dye. A blue dye is also obtained by heating mauvein with aniline. Aniline black is obtained by acting on aniline with a mixture of cupric sulphide or a vanadium salt and potassium chlorate. Saffronin is a base derived from commercial oils, rich in the superior homologues of aniline (toluidines). Its hydrochlorate is used in place of safflower. AZO AND DIAZO DERIVATIVES. The azo compounds are derivable from the aromatic hydrocarbons by loss of two H atoms from two molecules of the hydrocarbon, and union of the remainders through the intermediary of a group (—N = X—)". They are formed by the action of certain reducing agents upon the nitro-deriv- atives, and may be considered as intermediary products in the reduction of the nitro-derivatives to amines. Thus in the case of benzene : [C„H,(NO,)], + H. = 3tt,0 + cIh;-N/° Nitrobenzene. Azoxybenzene. C,h.-n\0 H _ HQ C.H-N\ C„H„ N / + • ~ " + C.H —bV Azoxybenz. ne. Azobenzene. C„H-N\ H - C*H*NH\ CcH-NX + ~ C6H6NH/ Azobenzene. Hydrazobenzene. c:h;nH/ + H, = 2[C,H,(NH,)] Hydrazobenzene. Aniline. The diazo compounds consist of an univalent remainder of an aromatic hydrocarbon, united by the group (—N = N—) with a haloid atom, or an acid residue : —N = N—Br — Diazobenzene bromide. PYRIDINE BASES. 317 HYDRAZINES. The hydrazines are theoretically derivable from the group H„N—NH., diamidogen, by the substitution of acid, alcoholic, or phenylic radicals for one or more of the hydrogen atoms. Phenyl hydrazine—C,H3—HN—NH2—is obtained by the action of zinc-dust and acetic acid on diazo-amidobenzene. It is a yellow oil, spar- ingly soluble in water, soluble in alcohol and in ether; possessed of strong reducing power, and acting as a monacid base to form crystallized salts. PYRIDINE BASES. These interesting substances, closely related to the vegetable alkaloids as well as to some of the alkaloids produced during putrefactive decompo- sition of animal matters, were first discovered in 1851, as constituents of oil of Dippel = oleum animale — oleum cornu cerci = bone-oil, an oil pro- duced during the dry distillation of bones, horns, etc., and as a by-prod- uct in the manufacture of ammoniacal compounds from those sources. They also occur in coal-tar, naphtha, and in commercial ammonia, me- thylic spirit, and fusel oil. The pyridine bases at present known are : Formula. Boiling-point. Sp. Gr. at 22°. Pyridine CrHsN 115° 0.924 Picoline C,H.N 134° 0.933 Lutidine C.HN 154° 0.945 Collidine CH„N 170° 0.953 Parvoline CttHuN 188° 0.966 Coridine C, Hr,N 211° 0.974 Rubidine C,,H17N 23(P 1.017 Viridine C, H, ,N 251° 1.024 It will be observed that these compounds are metameric with the ani- lines, from which they differ in constitution, as shown by the structural formulae of picoline and aniline : nh2 I ■ c / \ H-C C—H H—C C—H V I H C6H7N ch3 I c X \ H—C C—H I II H—C C—H \ / N CrH.N Aniline. Picoline. 318 MANUAL OF CHEMISTRY. They are all liquid at the ordinary temperature, behave as tertiary monamines, react with several of the general reagents of the alkaloids, and form chloroplatinates which are decomposed by boiling water. Pyridine—CH^^—*s stained rom oil of Dippel, and is also obtainable synthetically from piperidine, CH./ —H, which is itself a derivative of piperine, C12H906N, a constituent of black and white pepper. It is a colorless, mobile liquid, having a peculiar, very penetrating odor. It boils at 115° (239° F.). It mixes with water in all proportions. It is strongly alkaline, and combines with acids as does NH„. Like all the bases of this series, it is very stable, and withstands the action of such ox- idizing agents as fuming HN03 and chromic acid. It forms crystalline salts. Parvoline, C9HnN ; Collidine, C,HnN; and Hydrocollidine, C,H]3N—have been noted as products of putrefactive decomposition of albuminoids. Pyrrol—~ CH/—*s a base accompanying the py- ridine bases in oil of Dippel, and also obtainable from other sources. It is a colorless, oily liquid, whose odor resembles that of chloroform. By acting upon pyrrol with an ethereal solution of iodine, a quadrisub- stituted derivative, tetriodopyrrol, C4HI4N, is obtained as a brown powder, which has been used under the name Iodol as a substitute for iodoform in surgical practice. CHINOLINE BASES. The bases of this group at present known are : Chinoline C9H7N Lepidine CinH9N Cryptidine CuHnN Tetraliiroline CiaHlsN Pentahiroline C1SH -N Isoline C14HnN Ettidine C16H,^N Validine CJ6H21N whose constitution and relations to the pyridine bases are shown by the formula;: CH CH CH "V^CH I I I CH C CH 'cH Chinoline. c„h7n. Pyridine. C6H5N. They are obtained by the destructive distillation of the cinchonine, quinine, and other natural alkaloids, to which they are closely related. Chinoline—C^H.N—is a mobile liquid ; boils at 238° (4G0°.4 F ); be- comes rapidly colored on contact with air. It has an intensely bitter and acrid taste, and an odor somewhat like that of bitter almonds. It is sparingly soluble in water, readily soluble in alcohol and ether. INDIGO GROUP. 319 Chinoline is the nucleus of a vast number of products of substitution, among which are four substances which have recently assumed medical importance : Thalline = Tetrahydroparachinanisol—Clf)HnNO—is a derivative of the paramethyl ether of chinoline. It is met with in the form of sulphate and tartrate in the shape of crystalline powders. The odor of the sulphate is similar to that of anisol (methyl phenol); that of the tartrate to that of •coumarin. The taste of both is bitter, acrid, and salty. Both salts are readily soluble in HO, the sulphate the more readily. Solutions of thal- line salts assume, even when very dilute, a magnificent emerald-green color with Fe2Clc solution. Ethylthalline—C1„HnNO —is a derivative of thalline, whose chloride is hygroscopic ; readily forming solutions which are acid in reaction, bitter in taste, and assume a red-brown color with Fe.,Cl6. Antipyrine — Dimethyloxychinizine—CuH ,N O — is obtained by heating metkyloxychinizine with methyl iodide and methyl alcohol in sealed vessels at 100° (212° F.); the first-named substance having been previously obtained by the action of acetylacetic ether upon phenyl hydra- zine. It constitutes a voluminous, reddish, crystalline powder ; readily soluble in water, ether, alcohol, and chloroform. Its solution with Fe„Cl6 is colored deep red-brown, the color being discharged by H4S04. Nitrous acid colors dilute solutions of antipyrine a bright green, which persists for several days at the ordinary temperature. If the mixture be heated, and a drop of fuming HN03 added, the color changes to light red, then blood red, and the liquid deposits a purple oil on continued heating. Addition of a drop of fuming HN03 to a cold con- centrated solution of antipyrine produces precipitation of small green crystals. Kairine—Metliyloxychinoline hydride—CljH,.NO—is more nearly de- rived from chinoline than the substances previously mentioned. Its chlo- ride is a crystalline, nearly white, easily soluble powder, whose taste is at once bitter, aromatic, and salt}’. Thalline, ethylthalline, antipyrine, and kairine are possessed of anti- periodic and antipyretic properties. INDIGO GROUP. In this group are included a number of substances, derivable from indigo-blue, which are evidently closely related to the benzene group, as is shown by the number of benzene derivatives which are obtained by their decomposition, yet whose constitution is not yet definitely estab- lished. Indigotin—Indigo-blue—C16H10N„O2—constitutes the greater part of the commercial indigo. It does not exist preformed in the plants from which it is obtained, whose juice is naturally colorless, but is produced by decomposition of a glucoside contained in them (see Indican, p. 320). Indigotin may be obtained by the action of phosphorus trichloride on isatin; or, in a nearly pure form, by cautiously subliming commercial in- digo. It forms purple-red, somewhat metallic, orthorhombic prisms or plates, odorless, tasteless, neutral, insoluble in water, ether, or dilute acids or alkalies. By dry distillation it yields aniline and other products. 320 MANUAL OF CHEMISTRY. By moderate beating with dilute HN03 it gives off gas and is converted into isatin. Indigo Sulphonic Acids.—When indigo is heated for some time with fuming H2S04 it dissolves. If the solution be diluted with H20, a blue powder, soluble in H.,0, but insoluble in dilute acids, is precipitated. This is Indigo-monosulphonic or phoenicin-sidphonic acid—C]6HaN202S03H. The filtrate from the last-mentioned precipitate contains tndigo-disul- phonic, sulphindylic, or sulphindigotic acid—C16H8N20„(S03H)2—whose K and Na salts constitute soluble pastes known in the arts as soluble indigo, or indigocarmine. Isatin—CfH NOs—obtained by oxidation of indigo-blue, forms shin- ing, transparent, red-brown prisms. It is odorless, sparingly soluble in water, readily soluble in alcohol. Dioxindol—llgdrindic acid—C,H,NO ,—is formed by the action of Na on isatin suspended in H20. It forms yellow prisms, soluble in H„0, and combines with both bases and acids. Oxindol—CH7NO —is obtained from dioxindol by reduction with Na amalgam in acid solution. It crystallizes in easily soluble, colorless needles, and combines with acids and bases. Indol—C6H7N —is produced by distilling oxindol over zinc-dust, or by heating ortlionitrocinnamic acid with KHO and Fe filings. It crystallizes in large, shining, colorless plates, having the odor of naphthylamine. It is a weak base, forming salts with acids, which are, however, decomposed by boiling water. Its aqueous solution, acidulated with HC1, is colored rose-red by KN02. It is converted into aniline by fused KHO. It is one of the products of putrefaction of albuminoid substances, and is formed during the action of the pancreatic secretion upon albuminoids. It is partly eliminated with the feces and partly reabsorbed. In the intestine and feces indol is invariably accompanied by Skatol, C„H(JN, its superior homologue, which may also be obtained by the action of Sn and HC1 on indigo. It crystallizes in brilliant plates, and is less soluble than indigo. The product obtained from indigo has a penetrat- ing but not disagreeable odor, while that obtained from putrid albumin and from fecal or intestinal matter has a disgusting odor, probably due to the presence of foreign substances. Indican—C2(,H3 |N17 —is a glucoside existing in the different varieties of indigo-producing plants, and also in the urine and blood of man and the herbivora. It is a yellow or light-brown syrup, which cannot be dried without decomposition, bitter and disagreeable to the taste, acid in reaction, and soluble in water, alcohol, and ether. It is very prone to decomposition. Even slight heating decomposes it into leucin, indicanin, C20H„aNO12, and indiglucin, A characteris- tic decomposition is that when heated in acid solution, or under the in- fluence of certain ferments (?) it is decomposed into indigo-blue and indi- glucin, the latter a glucose : 2C„HJ1NO„ + 4H,0 = C„H„N,0, + 6C,H„0. Indican. Water. Indigotin. Indiglucin. SIXTH SERIES OF HYDROCARBONS. 321 SIXTH SERIES OF HYDROCARBONS. Series C„H2n_8. This series has at present but two representatives, derivable from ben- zene by the substitution of one lateral chain for an atom of hydrogen. Cinnamene—Styrolene—Cinnamol—Styrol—Liquid essence of styrax —C HS—104—exists ready formed in essential oil of styrax ; it is also formed by decomposition of cinnamic acid (q. v.), or, synthetically, by the action of a red heat upon pure acetylene, a mixture of acetylene and ben- zene, or a mixture of benzene and ethylene. It is a colorless liquid, has a penetrating odor, recalling those of benzene and naphthalene, and a pep- pery taste ; boils at 143° (289°.4 F.) ; soluble in all proportions in alcohol and water; neutral in reaction. ALCOHOLS. Series C„H.,„ O. There are but two alcohols of this series known : Cinnyl alcohol CaH10O | Cholesterin C.,(.Hl40 Cholesteric alcohol—Cholesterin—C36H43OH—372—is an alcohol, although usually classed by physiologists among the fats, because it is greasy to the touch and soluble in ether. It occurs in the animal economy, normally in the bile, blood (especially that coming from the brain), nerve-tissue, brain, spleen, sebum, contents of the intestines, meconium, and faeces ; pathologically in biliary calculi, in the urine in diabetes and icterus, in the fluids of ascites, hydrocele, etc., in tubercular and cancerous deposits, in cataracts, in atheromatous degenera- tions, and sometimes, in masses of considerable size, in certain cerebral tumors. It also exists in the vegetable world in peas, beans, olive-oil, wheat, etc. It has not been obtained by synthesis. It is best obtained from biliary calculi, the lighter-colored varieties of which consist almost entirely of this substance. The calculi are pulverized, extracted with boiling ether, the solution filtered hot, the ether distilled off, the residue dissolved in boiling alcohol, and the solution allowed to cool ; the crys- tals which separate are heated for some time with alcohol containing a little potash ; on cooling, crystals form, which are finally washed with al- cohol so long as the washings are colored or alkaline, and recrystalized from ether. Cholesterin crystallizes with or without Aq.; from benzol, petroleum, chloroform or anhydrous ether, it separates in delicate, colorless, silky needles, having the composition C26H440 ; from hot alcohol, or a mixture of alcohol, and ether, it crystallizes in rhombic plates, usually with one obtuse angle wanting, having the composition C2BH440 + 1 Aq.; these crys- tals, transparent at first, become opaque on exposure to air, from loss of aq. It is insoluble in water, in alkalies and dilute acids, difficultly soluble 322 MANUAL OF CHEMISTRY. in cold alcohol, readily soluble in hot alcohol, ether, benzol, acetic acid, glycerin, and solutions of the biliary acids. It is odorless and tasteless. When anhydrous it fuses at 145° (293° F.) and solidifies at 137° (278°.G F.); sp. gr. 1.046. It is laevogyrous, [a]D = 31°.G in any solvent. It combines readily Avith the volatile fatty acids. From its solution in glacial acetic acid a compound liaA'ing the composition C2filI440,C.,II402 separates in fine curved crystals, which are decomposed on contact Avith Avater or alcohol; when heated with acids under pressure, it forms true ethers. Hot HNO;i oxidizes it to cholesteric acid, C„H10O:, Avhich is also produced by the oxidation of biliary acids ; a fact Avhich indicates the prob- able existence of some relation between the methods of formation of cho- lesterin and of the biliary acids in the economy. Analytical Characters.—(1.) Moistened with HN03, and evaporated to dryness, a yellow residue remains, which turns brick-red on addition of NH4HO. (2.) It is colored violet when a mixture of 2 vols. H.,S04 (or HC1) and 1 vol. ferric chloride solution is evaporated upon it. (3.) When ground up Avith H,S04 and chloroform added, a blue-red or violet color is produced, which changes to green on exposure to air. SEVENTH SERIES OF HYDROCARBONS. Series CnHa„_10. The only representative of this series at present known is Naphthydrene—Naphthylene hydride — C]0H)0— 130 — obtained by heating naphthalene with potassium, and decomposing the product with water. It also occurs in heavy petroleum. It is a colorless liquid ; boils at 205° (401° F.), and has a strong, disagreeable odor. EIGHTH SERIES OF HYDROCARBONS. Series CnH.,„_12. The only term of this series is Naphthalene—C,, H.—128—occurring in coal-tar. It has been formed bv a synthesis which indicates its constitution ; benzene and ethylene, when heated together, unite to form, first, cinnamene and afterward naphthalene. It is constituted by the fusion of two benzol groups by two C atoms, thus : H H I I A /°\ H-C C C-H I II I H-C C C-H V}/ Ny^ I I H H NAPIITHOLS. 323 It crystallizes in large, brilliant plates ; has a burning taste and a faint aromatic odor; fuses at 80° (176° F.) and boils at 217: (422°.6 F.), sub- liming, however, at lower temperatures; burns with a bright, smoky flame ; insoluble in water, soluble in alcohol, ether, and essences. It forms substitution compounds with Cl, Br, I, HN03, and H3SOt. SUBSTITUTION DERIVATIVES OF NAPHTHALENE. By the replacement of the hydrogen atoms of naphthalene by other atoms or by radicals, substitution products are obtained somewhat in the same manner as in the case of benzene (see pp. 301, 304, 305). In the case of naphthalene, however, the number of isomeres is much greater than with benzene. In the structural formula of naphthalene the positions H H I I 8 1 r n / w \ H—7C C C2—H I II I H—GC C C3—H \ /y\ / c c 5 4 I I H H. 1, 4, 5, 8, although equal to each other, are of different value from the po- sitions 2, 3, 6, 7, also equal to each other, as the}' are differently disposed with regard to the carbon atoms x and y. There exist, therefor, two possible unisubstituted derivatives of naphthalene for a single such deriv- ative of benzene, etc. If the substituted group occupy the approximate positions 1, 4, 5, or 8, it is called an a-derivative ; if it occupy the remote positions 2, 3, 6, or 7, it is a /^-derivative. Of the numerous derivatives of naphthalene, the only ones of present medical interest are those corresponding to the monophenols: Naphthols—C1(,H.,OH—of which there are two : a-Naphthol has been obtained by heating plienyl-isocrotonic acid ; also by boiling an aqueous solution of diazonaphthalene nitrate with nitrous acid, or by fusing a-naphthalene-sulphonic acid with KHO. It crystallizes in colorless prisms ; fuses at 94° (201°.2 F.); boils at 280° (536° F.); is nearly insoluble in water, but soluble in alcohol and in ether, and gives a transient violet color with Fe„Clf and a hypochlorite. fi-Naphth ol = Isovaphthol—is prepared industrially by fusion of thalene sulphonate of sodium with NaHO, for the manufacture of a yellow dye stuff: Campobello yellow. The commercial product is in reddish-gray, friable, light masses. The pure substance forms colorless, silky, crystalline plates, having a faint, plienol-like odor, and an evanescent, sharp, burning taste. It fuses at 123° (253°.4 F.), boils at 286° (514°.8 F.), and is spar- ingly soluble in water, but readily soluble in alcohol and ether. Its aque- ous solutions are not colored violet by Fe3Clc. The pure substance is a valuable antiseptic. MANUAL OF CHEMISTRY. NINTH SERIES OF HYDROCARBONS. Series C„H.in_14. Is represented by a single hydrocarbon : Acenaphthalene—C12H]0— 154—produced synthetically by continuing the heating of naphthalene with ethylene, the reaction occurring in three steps. It also exists in coal-tar. TENTH SERIES OF HYDROCARBONS. Series CnH2n_16. Is represented by two terms: Fluorene, a solid, crystalline body, boil- ing at 305° (581° F.), obtained from coal-tar ; and Stiibene, obtained by the action of ammonium sulphydrate upon an alcoholic solution of benzoic aldehyde. ELEVENTH SERIES OF HYDROCARBONS. Series CnHvn_18. Anthracene—C, ,11,0—17&—exists as a constituent of coal-tar, and is obtained by expression from the substance remaining in the still after the distillation of naphthalene, etc. The commercial product thus obtained is a yellowish mass containing 50-80 per cent, of anthracene, the puri- fication of which is a matter of considerable difficulty. It has also been obtained synthetically, by the action of the heat on benzyl-toluene, and in other ways. When pure, anthracene crystallizes in rhombic tables having a bluish fluorescence ; fusible at 210° (410° F.) and boiling above 360° (6800 F.) ; its best solvents are benzene and carbon disulphide, in which, however, it is only sparingly soluble. The constitution of anthracene is that of two benzene nuclei united through two of their C atoms: H H i H c /c\ I /c\ H—C C—C—C C—H I II I II I H—C C—C—C C—H \c/ X I H I H H Oxidizing agents convert anthracene into anthraquinone. Reducing agents decompose it into three hydrocarbons, C14H30,C,H]6, and an oily 325 HIGHER SERIES OF HYDROCARBONS. hydrocarbon boiling above 3G0° (648° F.). Br and Cl attack it violently, I more slowly, forming products of addition. An isomere, Phenanthrene, CI4H10, which boils between 320° and 350° (608 -6623 F.), accompanies anthracene in the crude product. DERIVATIVES OF ANTHRACENE. As may be inferred from tlie complex molecule of anthracene, the number of possible derivatives of substitution and of addition, including many isomeres, is very great. Our knowledge of these derivatives is as yet fragmentary, and but few of those known are of present medical interest. /C°\ Anthraquinone—CeH4/ >C6H4—is formed by oxidation of an- xco/ thracene. It forms yellow needles, which fuse at 273° (523°.4 F.). It is not easily oxidized, but is converted into anthracene by sufficiently active reducing agents. 7co 7oh Dioxyanthraquinone — Alizarin — CeH / ;>C„H / —is the Nxk xoh red pigment of the madder root (Rubia tinctoria). Artificial alizarin has now almost completely displaced the natural product in dyeing. It is ob- tained by the action of fused KHO on many anthracene derivatives, the one generally used being anthraquinone-disulphonic acid, C14Hi.O„(SO;iH) . Methylanthracene—C14H9,CH3—is obtainable by synthesis, and also by heating clirysoplianic acid, emodin, or eloi'n with zinc-dust. Chrysophanie Acid—Pane tic Acid—Rheic Acid—Rhein, C,H04— is a derivative of methyl anthracene, which exists in the lichens Parmelia parietina and Squamaria elegans, in senna, and in rhubarb, and obtainable to the extent of 80 per cent, from Goa powder — Chrysarobin, C3 iH ,,.0_. Chrysophanie acid crystallizes in golden, orange-yellow, interlaced needles. It is almost tasteless and odorless ; fuses at 162° (291°.G F.); almost insoluble in cold water, sparingly soluble in hot water, alcohol, and ether, readily soluble in benzene. It forms a red solution with H.,S04, from which it is deposited, unchanged by water. It also forms red solu- tions with alkalies. Reducing agents convert it into methylanthracene. Trioxymethylanthraquinone — Emodin — C14H4(CH3)(0H)302 — occurs in the bark of Rhamnus franyula, and accompanies chrvso- phanic acid in rhubarb. It crystallizes in long, orange-red prisms which fuse at 2503 (482J F.), and yield methylanthracene when heated with zinc- dust. HIGHER SERIES OF HYDROCARBONS. The twelfth series is not at present represented Of the thirteenth series, one hydrocarbon, pyrene, ClfH)0, is known ; and one of the four- teenth series, chrysene, Clf(Hl2—both obtained from coal-tar. Pyrene crystallizes in plates ; fuses at 142° (287°.G F.). It forms a compound with picric acid, which crystallizes in red needles. Chrysene crystallizes in bright-yellow, glistening scales ; is sparingly soluble in alcohol, and forms a compound with picric acid which crystal- lizes in brown needles. MANUAL OF CHEMISTRY. CYANOGEN COMPOUNDS. The substances which we have so far considered are all derivable, more or less directly, from the various hydrocarbons, and may be considered, upon the theory of types, as produced by the substitution of radicals com- posed of C and H, C and O, or C, H and O, for atoms of H of the three typical substances H.,, H.,0 and H3N. The substances of this class are typically considered as containing the radical (CN)', which is known as cyanogen, and has the same power of passing unchanged from compound to compound, as do methyl and ethyl. Dicyanogen—(CN)2—52—is prepared by heating mercuric cyanide. It is a colorless gas ; has a pronounced odor of bitter almonds ; sp. gr. 1.8064 A.; burns in air with a purple flame, giving oT N and CO..,. It is quite soluble in H.O, the solution turning brown in air. With H20 alone, or with H20 and NHa, dicyanogen enters into com- binations which indicate the relations existing between the cyanogen compounds and those previously considered : (CN), + 4H20 = C204(NH4)2 (CN) + H20 = CNOH + CNH . Dicyanogen. Water. Ammonium oxalate. Dicyanogen. Water. Cyanic acid. Hydrocyanic acid. Cyanic acid. CNOH + H20 = NHa + C02 Water. CNOH + NH;1 = CON2H4 Ammonia. Carbon dioxide. Cyanic acid. Ammonia. Urea. It has a very deleterious action upon both animal and vegetable life, even when largely diluted with air. Hydrogen cyanide— Cyanogen hydride—Hydrocyanic acid—Prussic acid—| —27—exists ready formed in the juice of cassava, and is formed by the action of H.,0 upon bitter almonds, cherry-laurel leaves, etc. It is also formed in a great number of reactions : by the passage of the electric discharge through a mixture of acetylene and N ; by the action of chloroform on NHS ; by the distillation of, or the action of HN03 upon, many organic substances ; by the decomposition of cyanides. It is always prepared by the decomposition of a cyanide. Its prepara- tion in the pure form is an operation attended with the most serious danger, and should only be attempted by those well trained in chemical manipulation. For medical uses a very dilute acid is required; the acid, hydrocyanicum dil. (U. S., Br.) contains, if freshly and properly prepared, two per cent, of anhydrous acid ; that of the French Codex is much stronger —ten per cent. The pure acid is a colorless, mobile liquid, has a penetrating and characteristic odor; sp. gr. 0.7058 at 7° (44‘ .6 F.) ; crystallizes at —15° (5° F.); boils at 20°.5 (79°. 7 F.); is rapidly decomposed by exposure to light. The dilute acid of the U. S. P. is a colorless liquid, having the odor of the acid ; faintly acid, the reddened litmus returning to blue on exposure to air ; sp. gr. 0.997 ; 10 grams of the acid should be accurately neutralized by 1.27 gram of silver nitrate. The dilute acid deterioriates CYANOGEN COMPOUNDS. on exposure to light, although more slowly than the concentrated ; a trace of phosphoric acid added to the solution retards the decomposition. Most strong acids decompose HCN. The alkalies enter into double de- composition with it to form cyanides. It is decomposed by Cl and Br, with formation of cyanogen chloride or bromide. Nascent H converts it into methvlamine. Analytical Characters.—(1.) With silver nitrate a dense, white ppt. ; which is not dissolved on addition of HN03 to the liquid, but dissolves when separated and heated with concentrated HN03; soluble in solu- tions of alkaline cyanides or hyposulphites. (2.) Treated with NH4HS, evaporated to dryness, and ferric chloride added to the residue : a blood-red color. (3.) With potash and then a mixture of ferrous and ferric sulphates: a greenish ppt., which is partly dissolved with a deep blue color by II Cl. (4.) Heated with a dilute solution of picric acid and then cooled : a deep red color. (5.) Moisten a piece of filter paper with a freshly prepared alcoholic solution of guaiac ; dip the paper into a very dilute solution of CuS04, and, after drying, into the liquid to be tested. In the presence of HCN it as- sumes a deep blue color. Toxicology. —Hydrocyanic acid is a violent poison, whether it be in- haled as vapor or swallowed, either in the form of dilute acid, of soluble cyanide, or of the pharmaceutical preparations containing it, such as oil of bitter almonds and cherry-laurel water ; its action being more rapid when taken by inhalation or in aqueous solution than in other forms. When the medicinal acid is taken in poisonous dose, its lethal effect may seem to be produced instantaneously ; nevertheless, several respiratory efforts usually are made after the victim seems to be dead, and instances are not wanting in which there wras time for considerable voluntary motion between the time of the ingestion of the poison and unconsciousness. In the great majority of cases the patient is either dead or fully under the in- fluence of the poison on the arrival of the physician, who should, however, not neglect to apply the proper remedies if the faintest spark of life remain. Chemical antidotes are, owing to the rapidity of action of the poison, of no avail, although possibly chlorine, recommended as an antidote by many, may have a chemical action on that portion of the acid already absorbed. The treatment indicated is directed to the maintenance of respiration; cold douche, galvanism, artificial respiration, until elimination has removed the poison. If the patient survive an hour after taking the poison, the prognosis becomes very favorable ; in the first stages it is ex- ceedingly unfavorable, unless the quantity taken has been very small. In cases of death from hydrocyanic acid a marked odor of the poison is almost always observed in the apartment and upon opening the body, even several days after death. In cases of suicide or accident, the vessel from which the poison has been taken will usually be found in close proximity to the body, although the absence of such vessel is not proof that the case is one of homicide. Notwithstanding the volatility and instability of the poison, its pre- sence has been detected two months after death, although the chances of separating it are certainly the better the sooner after death the analysis is made. The search for hydrocyanic acid is combined with that for phos- phorus ; the part of the distillate containing the more volatile products is examined by the tests given above ; it is best, when the presence of free hydrocyanic acid is suspected, to distil at first without acidulating. MANUAL OF CHEMISTRY. In such cases the stomach should never he opened until immediately before the analysis. Cyanic acid—Cyanogen hydrate— jj O—43—does not exist in nature ; it is obtained by calcining the cyanides in presence of an oxidiz- ing agent ; or by the action of dicyanogen upon solutions of the alkalies or alkaline carbonates ; or by the distillation of cyanuric acid. It is a colorless liquid; has a strong odor, resembling that of formic acid ; its vapor is irritating to the eyes, and it produces vesication when applied to the skin ; it is soluble in water. When free it is readily changed by exposure to air into cyamelide. Sulphocyanic acid—Cyanogen sulphydrate——59—bears the same relation to cyanic acid that CS2 does to C0„. It is obtained by the decomposition of its salts, which are obtained by boiling a solution of the cyanide with S ; by the action of dicyanogen upon the metallic sul- phide ; and in several other ways. The free acid is a colorless liquid; crvstallizes at — 12°.o (9°.5 F.) ; boils at 102°.5 (21G°.5 F.) ; acid in reaction. The prominent reaction of the acid and of its salts is the production of a deep red color with the ferric salts ; the color being discharged by solution of mercuric chloride, but not by HC1. Sulphocyanic acid exists in human saliva in combination, probably, with sodium. The free acid is actively poisonous and its salts were for- merly supposed to be so also; it is probable, however, that much of the deleterious action of the potassium salt—that usually experimented with —is due as much to the metal as to the acid. Metallocyanides.— The radical cyanogen, besides combining with metallic elements to form true cyanides, in which the radical (CN) enters as a univalent atom, is capable of combining with certain metals (notably those of the iron and platinum groups) to form complex radicals. These combining with H, form acids, and with basic elements form salts in which the analytical reactions of the metallic element entering into the radical are completely masked. Of these metallocyanides the best known are those in which iron enters into the radical. As iron is capable of forming two series of compounds, in one of which the single atom Fe" enters in its bivalent capacity, and in the other of which the hexavalent double atom (Fe„)VI is contained ; so, uniting with cyanogen, iron forms two ferrocyanogen radicals: [(CN)'fFe''Jiv, ferrocyanogen, and [(CN)']2 (Fe2)v 1 ]v 1 ferricyanogen; each of which unites with hydrogen to form an acid, corresponding to which are numerous salts : (CfNfFe)H,, hydrofer- rocyanic acid, tetrabasic; and (CI2N12Fe2)H6, liydroferricyanic acid, hex- abasic (see potassium and iron salts). * COMPOUNDS OF UNKNOWN CONSTITUTION. GLUCOSIDES. Under this head are classed a number of substances, some of them im- portant medicinal agents, which are the products of vegetable or animal nature. Their characteristic property is that, under the influence of a dilute mineral acid, they yield glucose, phloroglucin or mannite, together with some other substance. Under the supposition that glucose and its GLUCOSIDES, congeners are alcohols, it is quite probable that the glucosides are their corresponding ethers. Amygdalin, ,—457—exists in cherry-laurel and in bitter almonds, but not in sweet almonds. Its characteristic reaction is that, in the presence of emulsin, which exists in sweet as well as in bitter almonds, and of water, it is decomposed into glucose, benzoic aldehyde, and hydrocyanic acid. The same reaction is brought about by boiling with dilute H3S04 or HC1. Bitter almonds contain about 2 per cent, of amygdalin. Digitalin.—The pharmaceutical products sold under the above name, and obtained from digitalis, are mixtures in varying proportions of several glucosides. Digitonin, C?1H6!!On, an amorphous, yellowish substance, very soluble in aqueous alcohol. Digitalin, CHO,, the principal constituent of the French digitalin, is a colorless, very bitter, crystalline solid, insoluble in water, soluble in alcohol. Digitalein, a white, intensely bitter, amorphous solid, very soluble in water, soluble in alcohol. Digitoxin, a colorless crystalline solid, insoluble in water, sparingly soluble in alcohol. It is not a glucoside, and is converted into toxiresin by dilute acids. The abstractum digitalis (U. S.) probably contains all the above, the ex- traction of the first being more complete with weak alcohol, that of the others with strong alcohol. J-lycyrrhizin.—A non-crystallizable, yellowish, pulverulent principle, obtained from liquorice ; soluble with difficulty in cold water, soluble in hot water, alcohol, and ether ; bitter-sweet in taste. By long boiling with dilute acids it is decomposed into glucose ,and glycyrrhetin, Clrhysician should, however, hear in mind that, in cases liable to give 7'ise to legal proceedings, these may become seriously complicated by the analysis of any parts of the body, dejecta, or suspected articles of food, etc., by any process open to attack by the most searching cross-examination. The substances to be examined are reduced to a fine state of subdivision, and are digested for an hour or more in water acidulated with S041I2, at a temperature of 40° to 50° (104°-122° F.); this is re- peated three times, the liquid being filtered and the solid material expressed. The united extracts are evap- orated at the temperature of the water-bath to a thin syrup; this is mixed with three or four volumes of alcohol, the mixture kept at about 86° (95° F.) for 24 hours, cooled well and filtered; the residue being washed with seventy per cent, alcohol. The alcohol is distilled from the filtrate, and the watery residue diluted with H20 and filtered. The filtrate so obtained contains the sulphates of the alkaloids, and from it the alkaloids themselves are separated by the following steps : A. The acid watery liquid is shaken with freshly rectified petroleum ether (which should boil at about 65°-70° (149°-]58° F.), and should be used with caution, as it is very inflammable): after several agitations the ether layer is allowed to separate and is removed ; this treatment is repeated so long as the ether dis- solves anything. The residue obtained by the evaporation of the ether—Residue I.—is mostly composed of coloring matters, etc., which it is desirable to remove. B. The same treatment of the watery liquid is repeated with benzene, which on evaporation yields Re- sidue II., which is, if crystalline, to be tested for cantharidin, santonin, and digitalin (q. v.); if amorphous, for elaterin and colchicin. C. The acid, aqueous fluid is then treated in the same way with chloroform to obtain Residue III., which is examined for cinchonine, digitalin, and picrotoxin by the proper tests. D. The watery fluid, after one more shaking with petroleum etller and removal of the ethereal layer, is rendered alkaline with ammonium hydrate and shaken with petroleum ether at 40° (104° F ), the ethereal layer being removed as quickly as possible while still warm; this is repeated two or three times, and repeated with cold petroleum ether, which is removed after a time. The warm ethereal layers yield Residue IV. a; the cold ones Residue IV. 6. The former is tested for strychnine, quinine, brucine, veratrine ; the latter for coniine and nicotine. E. The alkaline, watery fluid is shaken with benzene, which, on evaporation, yields Residue V.. which may contain strychnine, brucine, quinine, cinchonine, atropine, hyoscyamine, physostigmine, aconitine, co- deine, thebaine, and narceine. F. A similar treatment with chloroform yields Residue VI.. which may contain a trace of morphine. G. The alkaline liquid is then shaken with amyl alcohol, which is separated, and evaporated; Residue VII. is tested for morphine, solanin, and salicin. H. Finally, the watery liquid is itself evaporated with pounded glass, the residue extracted with chloro form, and Residue VIII., left by the evaporation of the chloroform, tested for curarine. VOLATILE ALKALOIDS. Volatile Alkaloids. Coniine—Conicine—Cicutine—C.H N—125—is obtained from Con- ium maculatum, in which it is accompanied by two other alkaloids, methyl- coniine, C5H14N(CH,), and conhydrine, C3HnNO—the former a volatile liquid, the second a crystalline solid. Coniine is a colorless, oily liquid ; has an acid taste and a disagree- able penetrating odor; sp. gr. 0.878; can be distilled when protected from air ; boils at 2123 (413°.6 F.) ; exposed to air it resinifies; it is very sparingly soluble in water, but is more soluble in cold than in hot water ; soluble in all proportions in alcohol, soluble in six volumes of ether, very soluble in fixed and volatile oils. The vapor which it gives off at ordinary temperatures forms a white cloud when it comes in contact with a glass rod moistened with HC1, as does NH3. It forms salts which crystallize with difficulty. Cl and Br combine with it to forai crystallizable compounds ; I in alcoholic solution forms a brown precipitate in alcoholic solutions of coniine, which is solu- ble without color in an excess. Oxidizing agents attack it with production of butyric acid (see below). The iodides of ethyl and methyl combine with it to form iodides of ethyl and methyl-conium. It has been obtained synthetically by first allowing butyric aldehyde and an alcoholic solution of ammonia to remain some months in contact at 30° (86 F.), when dibutyraldine is formed. 2(C4H„0) + Nil, = C8H17NO + H,0 Butyric aldehyde. Ammonia. Dibutyraldine. Water. The dibutyraldine thus obtained is then heated under pressure to 150°- 180° (302°-356° F.), when it loses water : C(H,,NO = CH1SN + H.o Dibutyraldine. Coniine. Water. A synthesis which, in connection with the decompositions of coniine, (c- N. H ) Analytical Characters.—(1.) With dry HC1 gas it turns reddish pur- ple, and then dark blue. (2.) Aqueous HC1 of sp. gr. 1.12 evaporated from coniine leaves a green-blue, crystalline mass. (3.) With iodic acid a white ppt. from alcoholic solutions. (4.) With H2S04 and evaporation of the acid : a red color, changing to green, and an odor of butyric acid. Nicotine—C10H]4N„—162—exists in tobacco in the proportion of 2-8 per cent. It is a colorless, oily liquid, which turns brown on exposure to light and air; has a burning, caustic taste and a disagreeable, penetrating odor; it distils at 250° (392° F.) ; it burns with a luminous flame ; sp. gr. 1.027 at 15° (593 F.) ; it is very soluble in water, alcohol, the fatty oils, and ether ; the last-named fluid removes it from its aqueous solution when the two are shaken together; it absorbs water rapidly from moist air. Its salts are deliquescent and crystallize with difficulty. 334 MANUAL OF CHEMISTRY. Analytical Characters.—(1.) Its ethereal solution, added to an ethereal solution of iodine, separates a reddish-brown, resinoid oil, which gradu- ally becomes crystalline. (2.) With HC1, a violet color. (3.) With HN03, an orange color. Both nicotine and coniine are actively poisonous, producing death by asphyxia, sometimes as rapidly as prussic acid. Fixed Alkaloids. These are much more numerous than those which are volatile, and form the active principles of a great number of poisonous plants. As we are yet in the dark" as to the constitution of these bodies, the classification which we adopt is the temporary one, based upon the botanic characters of the plants from which they are derived. Opium Alkaloids. Opium is the inspissated juice of the capsules of the poppy. It is of exceedingly complex composition, and contains, besides a neutral body called meconin (probably a polyatomic alcohol, C10H10O4), a peculiar acid, meconic acid (q. v.), lactic acid, gum, albumen, wax, and a volatile matter —no less than eighteen different alkaloids, one or two of which, how- ever, are probably formed during the process of extraction, and do not pre-exist in opium. The following is a list of the constituents of opium, those marked * being of medical interest: Name. Formula. Percent, in Smyrna opium. Fercent. in Constantino- ple opium. Name. Formula. j Percent, in Smyrna opium. j Percent, in Constantino- : pie opium. *Meconic acid. . c,h4o, 4.70 4.38 Laudanine C00H25NO4 Lactic acid CaHeOs 1.25 .... Papaverine C21H21SO4 1.00 0.08 0.30 Opianine C2iH,.,NO, "‘Morphine CnH.aNO, 10.30 4.50 Meconidine C2,h23no4 Pseudomorphine ci;h19no4 • • • • • • • • Cryptopine.... C21 H‘.’ O 5 .... H ydr ocotarnine. CijH16NOs Laudanosine.... C21H2,N04 1.30 3.47 c,.h,,no3 0.25 1.52 *Narcotine O7 Ci0H.,iNO3 C20H19NO5 C20H2.NO,, C20H20NO4 0.15 Lanthopine *Narceine C2SH09NO9 0.71 0.42 Rhasadine Codamine .... Porphyroxine... Morphine—Morphina(U. S.)—C _H NOa -f Aq—285 -f 18—crystal- lizes in colorless prisms ; odorless, but very bitter ; it fuses at 120 (248° F.), losing its Aq. More strongly heated, it swells up, becomes carbon- ized, and finally burns. It is soluble in 1,000 pts. of cold water, in 100 pts. of boiling water ; in 20 pts. of alcohol of 0.82, and in 13 pts of boil- ing alcohol of the same strength ; in 390 pts of cold amyl alcohol, much more soluble in the same liquid warm ; almost insoluble in aqueous ether ; OPIUM ALKALOIDS. rather more soluble in alcoholic ether ; almost insoluble in benzene ; solu- ble in 60 pts. of chloroform. All the solvents dissolve morphine more readily and more copiously when it is freshly precipitated from solutions of its salts than when it has assumed the crystalline form. Morphine combines with acids to form crystallizable salts, of which the chloride, sulphate, and acetate are used in medicine. If morphine be heated for some hours with excess of HC1, under pressure, to 150° (302° F.), it loses water, aud is converted into a new base—apomorphine, o„h„no. By the action of H.,S04 on morphine at 100 , two amorphous, ba- sic products of condensation, trimorphine and tetramorphine, are pro- duced. By heating together acetic anhydride and morphine, three modifica- tions, a, (3, y of acetyl-morphine, C17Hie(C.,H30)M0„, are formed. Simi- larly substituted butyryl-, benzoyl-, succinyl-, camphoryl-, methyl-, and ethyl- morphine are also known. Although the synthesis of morphine has not yet been accomplished, enough is known of its constitution to indicate that it contains the phenolic group (OH), and that it is a derivative of phenanthrene (see p. 325). The salts of morphine are crystalline. The acetate—Morphines Acetas, U. S.—Morphice Acetas, Br.—is a white, crystalline powder, soluble in 12 parts of water, which decomposes on exposure to air, with loss of acetic acid. The chloride—Morphines Hydrochloras, V. S.—is less soluble, but more permanent than the acetate. The sulphate—Morphines Sulphas, U. S.—Morphias Sulphas, Br.—is the form in which morphine is the most frequently used in medicine. It is a very light, crystalline, feathery pow- der ; odorless, bitter, and neutral in reaction. It dissolves in 24 parts of water. Its solutions deposit morphine as a white precipitate on addition of an alkali. The crystals contain 5 Aq., which they lose at 130° (266° F). Analytical Characters.—(1.) It is colored red, changing to yellow, by HNO, (2.) Cold concentrated H.,S04 dissolves it, forming a colorless solu- tion, which after 24 hours turns pink on addition of a trace of H N03; and the fluid when warmed, cooled, and diluted with H.,0, turns deep mahogany-brown on the addition of a splinter of potassium dichro- mate. (3.) A mixture of morphine and cane-sugar (1 to 4) added to concen- trated H,S04 gives a dark red color, which is intensified by a drop of bromine-water. (4.) If iodic acid solution and a drop of chloroform be added to mor- phine, free iodine is liberated, which colors the chloroform violet. If now dilute NH HO be floated on the surface of the liquid, a dark brown- ish zone is formed. (5.) A neutral solution of a morphine salt gives a blue color with neu- tral solution of ferric chloride. (6.) A solution of molybdic acid in H,S04 (Frolide’s reagent) gives with morphine a violet color, changing to blue, dirty green, and faint pink. Water discharges the color. (7.) Solution of morphine acetate produces a gray ppt. when warmed with ammoniacal silver nitrate solution ; and the filtrate turns red or pink with HNO,. (8.) Auric chloride gives a yellow ppt., turning violet-blue, with solu- tions of morphine salts. MANUAL OF CHEMISTUY. (9.) Add solution of Fe2Cl6 (2-1G) to solution of potassium ferri-cya- nide (the mixture must not assume a blue color), add morphine solution —a deep blue color. (10.) Heat morphine with concentrated H.2S04 to 200° (392° F.) until green-black ; add a drop of the liquid cautiously to water ; the solution turns blue. Shake a portion with ether ; the ether turns purple. Shake another portion with chloroform ; the chloroform turns blue. (11.) Warm the solid alkaloid with concentrated H2S04 ; add cau- tiously a few drops of alcoholic solution of KHO (30 $); a yellow color is produced, changing to dirty red, then steel blue, and sky blue, and, with a further quantity of KHO solution, cherry red. Codeine—Codeina (U.S.)—C18H21NOs + Aq—299 + 18—crystallizes in large rhombic prisms, or from ether, without Aq., in octahedra ; bit- ter ; soluble in 80 pts. cold water ; 17 pts. boiling water; very soluble in alcohol, ether, chloroform, benzene ; almost insoluble in petroleum ether. Analytical Characters.—(1.) Cold concentrated H.4S04 forms with it a colorless solution, which turns blue after some days, or when warmed, (2.) Frohde’s reagent dissolves it with a dirty green color, which after a time turns blue. (3.) Chlorine water forms with.it a colorless solution which turns yel- lowish red with NH HO. N arc sine—C23H2i)N09 + 2 Aq —463 + 36—crystallizes in bitter, pris- matic needles ; sparingly soluble in water, alcohol, and amyl alcohol; in- soluble in ether, benzol, and petroleum ether. Analytical Characters.—(1.) Concentrated HJS04 dissolves it with a gray brown color, which changes to red, slowly at ordinary temperatures, rapidly when heated. (2.) Frohde’s reagent colors it dark olive green, passing to red after a time, or when heated. (3.) Iodine solution colors it blue violet, like starch. Narcotine—C, ,H,..NO. — 413—crystallizes in transparent jDrisms, almost insoluble in water and in petroleum ether ; soluble in alcohol, ether, benzol, and chloroform. Its salts are mostly uncrystallizable, unstable, and readily soluble in water and alcohol. Analytical Characters. — (1.) Concentrated II2S04 forms with it a solution, at first colorless, in a few moments yellow, and after a day or two, red. (2.) Its solution in dilute H2S04, if gradually evaporated until the acid volatilizes, turns orange red, bluish violet, and reddish violet. (3.) Frohde’s reagent dissolves it with a greenish color, passing to cherry red. Thebaine — Paramorphine— C H NO.,—311—crystallizes in white plates ; tasteless when pure ; insoluble in water ; soluble in alcohol, ether, and benzol. Analytical Characters.—(1.) With concentrated H2S04 an immediate bright red color, turning to yellowish red. (2.) Its solution in chlorine water turns reddish-brown with NH4HO. (3.) With Frohde’s reagent same as 1. Meconic acid—C.H O. + 3Aq—200 + 54—is a tribasic acid, peculiar to opium, in which it exists in combination with a part, at least, of the alkaloids. It crystallizes in small prismatic needles; acid and astringent in taste ; loses its Aq at 120° (248° F.); quite soluble in water; soluble in alcohol; sparingly soluble in ether. Analytical Characters.—With ferric chloride, a blood-red color, which CINCHONA ALKALOIDS. is not discharged by dilute acids or by mercuric chloride ; but is discharged by stannous chloride and by the alkaline hypochlorites. Apomorphine—C17HMNOa—is used hypodermically as an emetic in the shape of the chloride, apomorphince hydrochloras, U. S. It is obtained by sealing morphine with an excess of strong HC1 in a thick glass tube, and heating the whole to 1403 (252° F.) for two to three hours. It is ob- tained also by the same process from codeine. The free alkaloid is a white, amorphous solid, difficultly soluble in water. The chloride forms colorless, shining crystals, which have a tendency to assume a green color on exposure to light and air. It is odorless, bitter, and neutral; soluble in 6.8 parts of cold water. Toxicology of Opium and its Derivatives.—Opium, its preparations and the alkaloids obtained from it are ail active poisons. They produce drow- siness, stupor, slow and stertorous respiration, contraction of the pupil ; small and irregular pulse, coma, and death. The symptoms set in from 10 minutes to 3 hours, sometimes immediately, sometimes only after 18 hours. Death has occurred in from 45 minutes to 3 days, usually in 5-18 hours. After 24 hours the prognosis is favorable. Death has been caused in an adult by one-half grain of acetate of morphia, while 30 grains a day have been taken by those accustomed to its use without ill effects. The alkaloids of opium have not the same action. In soporific action, beginning with the most powerful, they rank thus : Narceine, morphine, codeine ; in tetanizing action : thebaine, papaverine, narcotine, codeine, mor- phine ; in toxic action : thebaine, codeine, papaverine, narceine, morphine, narco tine. The treatment should consist in the removal of unabsorbed poison from the stomach by emesis and the stomach-pump, and washing out of the stomach after injection into it of powdered charcoal in suspension, or tea or coffee infusion. Cold affusions should be used and the patient kept awake. After death the reactions for meconic acid and narcotine permit of dis- tinguishing whether the poisoning was by opium or its preparations, or by morphine. Cinchona Alkaloids Although by no means so complex as opium, cinchona bark contains a great number of substances : quinine, cinchonine, quinidine, cinchonidine, aricine; quinic, quinotannic, and quinovic acids; cinchona red, etc. Of these the most important are quinine and cinchonine. Quinine—Quinina (U. S.)—C„0H.24N.2O5 + n Aq.—324+nl8—exists in the bark of a variety of trees of the genera Cinchona and China, indigenous in the mountainous regions of the north of South America, which vary considerably in their richness in this alkaloid, and consequently in value ; the best samples of calisava bark contain from 30 to 32 parts per 1,000 of the sulphate ; the poorer grades 4 to 20 parts per 1,000 ; inferior grades of bark contain from mere traces to 6 parts per 1,000. It is known in three different states of hydration, with 1, 2, and 3 Aq. and anhydrous. The anhydrous form is an amorphous, resinous sub- stance, obtained by evaporation of solutions in anhydrous alcohol or ether. The first hydrate is obtained in crystals by exposing to air recently pre- cipitated and well-washed quinine. The second by precipitating by am- monia a solution of quinine sulphate, in which H has been previously liberated by the action of Zn upon H„S04; it is a greenish, resinous 338 MANUAL OF CHEMISTRY. "body, which loses H20 at 150° (302° F.). The third, that to which the following remarks apply, is formed by precipitating solution of quinine salts with ammonia. It crystallizes in hexagonal prisms ; very bitter; fuses at 57° (134°.6 F.); loses Aq. at 100° (212° F.) and the remainder at 125° (257c F.) ; becomes colored, swells up, and, finally, burns with a smoky flame. It does not sublime. It dissolves in 2,200 pts. of cold H.O, in 760 of hot 11,0 ; very soluble in alcohol and chloroform ; soluble in amyl alcohol, benzene, fatty and essential oils, and ether. Its alcoholic solution is powerfully laevogy- rous, [a]n = —270°.7 at 18° (64°.4 F.), which is diminished by increase of temperature, but increased by the presence of acids. Analytical Characters.—(1.) Dilute H,S04 dissolves quinine in color- less but fluorescent solution (see below). (2.) Solutions of quinine salts turn green when treated with Cl and then with NII3. (3.) Cl passed through H.,0 holding quinine in suspension forms a red solution. (4.) Solution of quinine treated with Cl water and then with fragments of potassium ferrocyanide becomes pink, passing to red. Sulphate—Disulphate—Quinince sulphas (US.)—Quinice sulphas (Hr.)— SO(C0HicN,yO.X -f- 7Aq—746 + 126—crystallizes in prismatic needles; very light; intensely bitter; phosphorescent at 100 (2123 F.); fuses readily ; loses its Aq. at 120° (248° F.), turns red, and finally carbonizes ; effloresces in air, losing 6 Aq.; soluble in 740 pts. H,0 at 13 (55 .4 F.), in 30 pts. boiling H20, and 60 pts. alcohol. Its solution with alcoholic solution of I deposits brilliant green crystals of iodoquinine sulphate. Hydrosulphate—Quinince bisulphas (U. S.)—S04H + 7Aq. —422 + 126—is formed when the sulphate is dissolved in excess of dilute H„S04. It crystallizes in long, silky needles, or in short, rectangular prisms ; soluble in 10 pts. H.,0 at 15° (59° F.). Its solutions exhibit a marked fluorescence, being colorless, but showing a fine pale blue color when illuminated by a bright light against a dark background. Impurities.—Quinine sulphate should respond to the following tests : (1.) When 1 gram (15.4 grains) is shaken in a test tube with 15 c.c. (4 II 3 ) of ether, and 2 c.c. (32 TTF) of NH4HO ; the liquids should sep- arate into two clear layers, without any milky zone between them (cin- chonine). (2.) Dissolved in hot H O, the solution precipitated with an alkaline oxalate, the filtrate should not ppt. with XH HO (quinidine). (3.) It should dissolve completely in dilute H„S04 (fats, resins). (4.) It should dissolve completely in boiling, dilute alcohol (gum, starch, salts). (5.) It should not blacken with H„S04 (cane-sugar). (6.) It should not turn red or yellow with H„S04 (salicin and phlorizin). (7.) It should leave no residue when burnt on platinum foil (mineral substances). By the action of alkaline hydrates upon quinine, formic acid, cliinoline (see p. 318), and pyridine bases (see p. 317) are produced. Concentrated HC1 at 140°-150° (284°-3025 F.) decomposes quinine, with separation of methyl chloride and formation of apoquinine, C]; H22N2 O,, an amorphous base. Oxidizing agents produce from quinine oxalic acid and acids related to pyridine, notably pyridindicarbonic or cinchomeronic acid, C.H. N(COOH)2, which are also formed by oxidation of cinchonine. STRYCHNOS ALKALOIDS. 339 Although cinchonine (see below) differs from quinine in composition by -f O, and although the decompositions of the two bases show them both to be related to the chinoline and pyridine bases, attempts to convert cinchonine into quinine have resulted only in the formation of other prod- ucts, among which is an isomere of quinine, oxycinchonine. Methylquinine, CJ?H Na02CH3, is a base which has a curare-like action. Cinchonine—Cinchonina (U. S.)—C,H N O—294—occurs in Peru- vian bark in from 2 to 30 pts. per 1,000. It crystallizes without Aq. in colorless prisms ; fuses at 150° (302° F.) ; soluble in 3,810 pts. H.,0 at 10° (50° F.), in 2,500 pts. boiling H,0 ; in 140 pts. alcohol and in 40 pts. chloroform. The salts of cinchonine resemble those of quinine in composi- tion ; are quite soluble in HaO and alcohol; are not fluorescent; perma- nent in air ; phosphorescent at 100J (212° F.). Quinidine and Quinicine—are bases isomeric with quinine ; the former occurring in cinchona bark, and distinguishable from quinine by its strong dextrorotary power; the second a product of the action of heat on quinine, not existing in cinchona. Cinchonidine—a base, isomeric with cinchonine, occurring in certain varieties of bark; kevogyrous. At 130° (266° F.) H,S04 converts it into another isomere, cinchonicine. Caffeine—Theine—Guaranine—Caffeina (U. S.)—C.HNO -4- Aq— 194 + 18—exists in coffee, tea, Paraguay tea, and other plants. It crys- tallizes in long, silky needles ; faintly bitter ; soluble in 75 pts. HsO at 15° (59° F.) ; less soluble in alcohol and ether. Hot fuming HXOs con- verts it into a yellow liquid, which after evaporation, turns purple with nh4ho. Alkaloids of the Loganiaceae. Strychnine—Strychnina (U. S.)—C41HS5NaOs—334—exists in the seeds and bark of different varieties of strychnos. It crystallizes on slow evaporation of its solutions in orthorhombic prisms, by rapid evaporation as a crystalline powder ; very sparingly solu- ble in 11,0 and in strong alcohol ; soluble in 5 pts. chloroform. Its aqueous solution is intensely bitter, the taste being perceptible in a solu- tion containing 1 pt. in 600,000. It is a powerful base ; neutralizes and dissolves in concentrated H2S04 without coloration ; and precipitates many metallic oxides from solutions of their salts. Its salts are mostly crystallizable, soluble in H.,0 and alco- hol, and intensely bitter. The acetate is the most soluble. The neutral sulphate crystallizes, with 7 Aq., in rectangular prisms. The iodides of methyl and ethyl react with strychnine to produce the iodides of methyl or ethylstrychnium, whitQ crystalline basic substances, producing an ac- tion on the economy similar to that of curare. When acted on by H,S04 and potassium chlorate, with proper precautions, strychnic or igasuric acid is formed. Analytical Characters.—(1.) Dissolves in concentrated H SO , without color. The solution deposits strychnine when diluted with H.,0, or when neutralized with magnesia or an alkali. (2.) If a fragment of potassium dichromate (or other substance capable of yielding nascent O) is drawn through a solution of strychnine in H,S04, it is followed by a streak of color ; at first blue (very transitory and fre- quently not observed), then a brilliant violet, which slowly passes to rose- pink and finally to yellow. Reacts with grain of strychnine. 340 MANUAL OF CHEMISTRY. (3.) .A dilute solution of potassium dichromate forms a yellow, crystal- line ppt. in strychnine solutions; which, when washed and heated with concentrated H.,S04 gives the play of colors indicated in 2. (4.) If a solution of strychnine be evaporated on a bit of platinum foil, the residue moistened with concentrated H.,S04, the foil connected with the + pole of a single Grove cell, and a platinum wire from the — pole brought in contact with the surface of the acid, a violet color appears upon the surface of the foil. (5.) Strychnine and its salts are intensely bitter. (6.) A solution of strychnine introduced under the skin of the back of a frog causes difficulty of respiration and tetanic spasms, which are aggra- vated by the slightest irritation, and twitching of the muscles during the intervals between the convulsions. With a small frog, whose surface has been dried before injection of the solution, grain of acetate of strychnine will produce tetanic spasms in 10 minutes and death in 2 hours. (7.) Solid strychnine, moistened with a solution of iodic acid in H..SO,, produces a yellow color, changing to brick-red and then to violet-red. (8.) Moderately concentrated HN03 colors strychnine yellow in the cold. A pink or red color indicates the presence of brucine. Toxicology.—Strychnine is one of the most active and most frequently used of poisons. It produces a sense of suffocation, thirst, tetanic spasms, usually opisthotonos, sometimes emprostliotonos, occasionally vomiting, contraction of the pupils during the spasms, and death, either by asphyxia during a paroxysm or by exhaustion during a remission. The symptoms appear in from a few minutes to an hour after taking the poison, usually in about 20 minutes ; and death in from 5 minutes to G hours, usually within 2 hours. Death has been caused by grain, and recovery has fol- lowed the taking of 20 grains. The treatment should consist of the removal of the unabsorbed poison by the stomach-pump, injecting chai-coal, and pumping it out after about 5 minutes ; under the influence of chloroform if necessary. Chloral hydrate should be given. Strychnine is one of the most stable of the alkaloids, and may remain for a long time in contact with putrefying organic matter without suffering decomposition. Brucine—C23H28N204 + 4 Aq —394 + 72—accompanies strychnine. It forms oblique rliomboidal prisms, which lose their Aq. in dry air. Sparingly soluble in H30; readily soluble in alcohol, chloroform, and amyl alcohol; intensely bitter. It is a powerful base and most of its salts are soluble and crystalline. Its action on the economy is similar to that of strychnine but much less energetic. Analytical Characters. — (1.) Concentrated HN03 colors it bright red, soon passing to yellow ; stannous chloride, or colorless NHHS, change the red color to violet. (2.) Chlorine water, or Cl, color brucine bright red, changed to yellow- ish brown by NH HO. Alkaloids of the Solanaceae. Solanine—C^H.jNO^—857—obtained from many species of Solarium; crystallizes in small, white, bitter, sparingly soluble prisms. Concen- trated H.SO, colors it orange red, passing to violet and then to brown. It is colored yellow by concentrated HC1. It dissolves in concentrated ALKALOIDS 341 HN03, the solution being at first colorless, but after a time becomes pur- ple. Atropine—Daturine—Atropina, U. S.—Atropia, Br.—C17H23N03— 289—occurs in atropa belladonna and in datura stramonium. It forms colorless, silky needles, which are sparingly soluble in cold water, more readily soluble in hot water, very soluble in chloroform. It is odor- less, but has a disagreeable, persistent bitter taste. It is distinctly alkaline, and neutralizes acids with formation of salts. One of these, the sulphate—Atropines Sulphas, U. S.—is a white, crystalline powder, readily soluble in water, which is the form in which atropine is usually adminis- tered. Toxicology.—It is actively poisonous, producing drowsiness, dryness of the mouth and throat, dilatation of the pupils, loss of speech, diplopia, dizziness, delirium, coma. The treatment should consist i:i the administration of emetics and the use of the stomach-pump. Analytical Characters.—(1.) If a fragment of potassium dichromate be dissolved in a few drops of H.,S04, the mixture warmed, a fragment of atropine and a drop or two of H.,0 added, and the mixture stirred, an odor of orange-blossoms is developed. (2.) A solution of atropine dropped upon the eye of a cat produces di- latation of the pupil. (3.) The dry alkaloid (or salt) is moistened with fuming HN03 and the mixture dried on the water-bath. When cold it is moistened with an al- coholic solution of KHO—a violet color which changes to red. When atropine is heated with concentrated HC1 to 120°-130° (248°- 266° F.) for several hours, or when it is warmed with baryta-water to 58° (136°.4 F.) it is decomposed into a base related to the pyridines : Tropine —C7H1L—OH, NCH3—and, at first, tropic acid—C2H10O3—but later atropic acid—CH2—C(CGH5)COOH. Tropine is also produced by a similar decomposition of liyoscyamine. Hyoscyamine—C15H23N03—occurs, along with another base, hyos- cine, isomeric with atropine, in hyoscyamus niger. It crystallizes, when pure, in odorless, white, silky needles, whose taste is very sharp and dis- agreeable, and which are very sparingly soluble in water. As most com- monly met with, it forms a yellowush, soft, hygroscopic mass which gives off a peculiar, tobacco-like odor. It neutralizes acids. Its sulphate—Hyos- cyamincs Sulphas, U. S.—forms yellowish crystals, very soluble in water, hygroscopic, and neutral in reaction. Alkaloids from other Sources. Ergotine—C50H52N2O3 —and Ecboline—are two brown, amorphous, faintly bitter, and alkaline alkaloids obtained from ergot. They are read- ily soluble in water and form amorphous salts. The medicinal prepara- tions known as ergo tine are not the pure alkaloid. Colchicine—C17H19N06—occurs in all portions of colchicum autam- nale and other members of the same genus. It is a yellowish-white, gummy, amorphous substance, having a faintly aromatic odor and a per- sistently bitter taste. It is slowly but completely soluble in water, form- ing faintly acid solutions. It forms salts which are, however, very unsta- ble. MANUAL OF CHEMISTJIY. Concentrated HXOs, or, preferably, a mixture of HaS04 and XaX03 colors colchicine blue-violet. If the solution be then diluted with H..O, it becomes yellow, and on addition of XaHO solution, brick-red. Veratrine—Vercitrina, U. S.—C3„H,N„Oh—occurs in veratrum offici- nalis = asagrcea officinalis, accompanied by Sabadilline—C. H N O — Jervine—Ca(lH4rNo03—and other alkaloids. The substance to which the name Veratrina, U. S., applies is not the pure alkaloid, but a mixture of those occurring in the plant. Concentrated H.,S04 dissolves veratrine, forming a yellow solution turn- ing orange in a few moments, and then, in about half an hour, bright car- mine red. Concentrated HC1 forms a colorless solution with veratrine, which turns dark red when cautiously heated. Piperine—CnH19NO 3—occurs in black and white pepper. It crystal- lizes in colorless, transparent prisms ; almost tasteless when pure ; very sparingly soluble in water. It is a very weak base. If piperine be heated with alcoholic IvHO, it is decomposed \\\to piper- idine—CJduN—and piper ic acid—C1.,HloOJ. If piperidine be treated with silver oxide, pyridine (see p. 317) is formed. Berberine—Xanthopicrite—C20H]7NO4—occurs in berberis vulgaris, cocculus palmatus, and many other plants. It crystallizes in fine yellow needles or prisms ; bitter in taste and neutral in reaction. It is diffi- cultly soluble in cold water, readily soluble in alcohol and in boiling water. It forms well-defined, crystalline, yellow salts. Aconitine—Ca6H35N07(0H)30(C0,CrH6)—is an alkaloid obtained from aconitum napellus and other species of aconitum. It is a colorless and odorless powder, possessed of an intensely bitter taste, and sharp, burning after-taste. It is strongly alkaline ; almost insoluble in water, readily solu- ble in alcohol, ether, chloroform, or benzene. It neutralizes acids com- pletely, with formation of well-defined, crystalline salts. Aconite contains, besides aconitine, three other alkaloids, if not a greater number: Napelline, acolyctine, and lycoctonine. These three alkaloids, no- tably the first named, along with small quantities of aconitine, constitute the English or Morson’s “ aconitine,” which is probably made from aconi- tum fero.r. Probably, also, all commercial samples of aconitine are mix- tures of aconitine and nepalline with lesser quantities of the other alka- loids and aconine and pseudaconine. If aconitine be heated in sealed tubes with H,,0 to 140°-150° (284°- 302° F.) for several hours, it is decomposed into benzoic acid and aconine, C2PH36N07(0H)4. A Japanese variety of aconite contains a peculiar alkaloid : Japaconiline, C.A.X.O, Analytical Characters.—(1.) Concentrated H„S04 dissolves aconitine, forming a light, yellow-brown solution, which slowly turns darker, and changes to light yellow on addition of HNOa. (2.) If aconitine be dissolved in aqueous phosphoric acid, and the solution very gradually evaporated, a violet color is produced. Toxicology.—Aconite and aconitine have been the agents used in quite a number of homicidal poisonings. The symptoms usually manifest themselves within a few minutes; some- times are delayed for an hour. There is numbness and tingling, first of the mouth and fauces, later becoming general. There is a sense of dryness and of constriction in the throat. Persistent vomiting usually occurs, but is absent in some cases. There is diminished sensibility, with numbness, PTOMAENES great muscular feebleness, giddiness, loss of speech, irregularity and fail- ure of the heart’s action. Death may result from shock if a large dose of the alkaloid be taken, but more usually it is by syncope. The treatment should be directed to the removal of unabsorbed poison by the stomach-pump, and washing out of the stomach with in- fusion of tea holding powdered charcoal in suspension. Stimulants should be freely administered. Pilocarpine—C]1Hi(.N,Oj—is the principal alkaloid of jaborandi. It forms a colorless, amorphous mass, readily soluble in water, alcohol, ether, and chloroform. It readily forms salts. Its chloride—Pilocarpince hy- drochloras, V. S.—occurs in white, deliquescent, odorless crystals. Cocaine—CJ7H2104—is an alkaloid obtained from the leaves of ery- throxylon coca. It crystallizes in large, six-sided prisms. Its taste is at first bitter, producing paralysis of the sense of taste subsequently. It is strongly alkaline. Its chloride, extensively used for the production of local amestliesia, crystallizes in well-formed prismatic needles, readily sol- uble in water. When heated with concentrated HC1, it is decomposed into benzoic acid, methyl alcohol, and a new base, ecgonin, C.jH^NO,. Physostigmine—Eserine—Cj.H^N^O.,—is an alkaloid existing in the Calabar bean, physostogma venenosum. It is a colorless, amorphous solid, odorless and tasteless, alkaline and difficultly soluble in water. It neutralizes acids completely, with formation of tasteless salts. Its sali- cylate—Physostigmince Salicylas, U. S.—forms short, colorless, prismatic crystals, sparingly soluble in water. Concentrated H.,S04 forms a yellow solution with physostigmine or its salts, which soon turns olive-green. Concentrated HN03 forms with it a yellow solution. If a solution of the alkaloid in H2S04 be neutralized with NHHO, and the mixture warmed, it is gradually colored red, red- dish yellow, green, and blue. Curarine—C3(,H, rN' (?)—is an alkaloid obtainable from the South American arrow-poison, curare, or icoorara. It crystallizes in four sided, colorless prisms, which are hygroscopic, faintly alkaline, and intensely bit- ter. Curarine dissolves in H2S04, forming a pale violet solution, which slowly changes to red. If a crystal of potassium dichromate be drawn through the H2S04 solution, it is followed by a violent coloration, which differs from the similar color obtained with strychnine under similar cir- cumstances, in being more permanent, and in the absence of the following pink and yellow tints. Emetine—C,,H1 N,0 5—an alkaloid existing in ipecacuanha, which crystallizes in colorless needles or tabular crystals, slightly bitter and acrid ; odorless, and sparingly soluble in water. It dissolves in concentrated forming a green solution, which gradually changes to yellow. With Frohde’s reagent it gives a red color, which soon changes to yellowish-green and then to green. Ptomaines. This name, derived from irrMfxa = that which is fallen—i.e., a corpse— was lirst suggested by Selmi to apply to a class of substances, first distinctly recognized by him, which are produced from albuminoid substances under 344 MANUAL OF CHEMISTRY. tlie influence of putrefactive decomposition, and which are distinctly alka- loidal in character. The ptomaines are possessed of all of the distinguishing characters of the vegetable alkaloids. They are alkaline in reaction, and combine with acids to form salts. Some are liquid, others are solid and crystalline. Some are actively poisonous, others are practically inert. They behave to- ward the general reagents for alkaloids in much the same way as do the vegetable alkaloids. Although the names ptomaines and cadaveric alkaloids are applied to al- kaloids of animal origin, it is certain that such alkaloids may be and are produced during life in the animal economy. It was feared that, as alkaloidal substances in many respects resembling those of vegetable origin are produced in the animal body, not only after death, but during life, grave doubts would be cast upon the results of an- alyses made to detect the presence of poisonous vegetable alkaloids in the cadaver in cases of suspected poisoning. Such fears were by no means groundless, as there is abundant evidence that ptomaines have been mis- taken for vegetable alkaloids in chemico-legal analyses. The ptomaines, however, as well as the vegetable alkaloids, may be positively identified by a careful analysis based upon the use, not of a single reaction, but of all known reactions for the alkaloid in question. Therefor, it is possible to positively predicate the existence or non-existence of a given vegetable al- kaloid in a cadaver, but it can only be done after a thorough and conscien- tious examination by all physiological and chemical reactions. The ptomaines have of recent years assumed great importance to the physician by reason of their bearing upon the etiology of disease, and suf- ficient experimental evidence has already been obtained to warrant the be- lief that the method of action of many of the known pathogenic bacteria is by their production of alkaloidal poisons (see below). One of the first of the putrid alkaloids to be formed in cadaveric matter is choline (see pp. 207, 273), which undoubtedly has its origin in the de- composition of the lecithins. Neuridine—CtHi4N2 (?)—is a diamine, related to neurine (see p. 208), which is formed during the early stages of cadaveric putrefaction. It is gelatinous, readily soluble in water, insoluble in alcohol and ether, and very prone to decomposition, yielding dimetliylamine and trimetliylamine. It forms a chloride which crystallizes in long, transparent needles, very sol- uble in water. It is non-poisonous. Cadaverine—CH 4N2—identical with pentametliylendiamine, NH— (CH,)ri—NH„ is formed at a somewhat later stage of cadaveric putrefac- tion, along with putrescine and saprine (see below). Its chloride is crystalline, hygroscopic, very soluble in water, insolu- ble in strong alcohol and ether. Like most of the ptomaines and sev- eral of the vegetable alkaloids, it gives a distinct blue color with ferric chloride and potassium ferricyanide. It is non-poisonous. Putrescine—C4H ,N2—and Saprine—CrHrN—are two non-poison- ous diamines produced along with cadaverine. They are both liquid, and each forms a crystalline chloride. Mydaleine is a putrid alkaloid, of undetermined composition, forming a difficultly crystallizable, hygroscopic chloride, which is actively poison- ous. Five milligrammes administered hypodermically to a cat causes death after profuse diarrhoea and secretion of saliva, violent convulsions, and paralysis beginning with the extremities and extending to the muscles of respiration, ALBUMINOIDS AND GELATINOIDS. Neurine (see p. 208) is produced during the later stages of putrefac- tion. It is actively poisonous, and produces symptoms similar to those caused by muscarine. Atropine is a powerful antidote to its action. Mydine—Ct,Ki NO —is a base produced after continued putrefaction at comparatively low temperatures. It is a powerful base, and a strong re- ducing agent, and has an ammoniacal odor. It is uon-poisonous. Mydatoxine—C6H13NOa—is a strongly alkaline syrup, which pro- duces, when administered to animals, violent clonic spasms, followed by paralysis and death. Other ptomaines produced during putrefaction of meat, fish, etc., are methylguanidine, CaH7N3—poisonous ; muscarine, C6H15NOa—poi- sonous ; and gadinine, C.Hi;NO.,—non-poisonous. An alkaloid, many of whose chemical reactions have been determined, although its composition is unknown, has been obtained from the inter- nal organs, and dejecta of cholera victims, as well as from cultures of the comma bacillus. This alkaloid, when administered to animals, causes symptoms of poisoning and death. From the cultures of the Ivoch-Ebertli typhus bacillus an alkaloid has been isolated—Typhotoxine—C.HnNOs—which, when administered to animals, causes paralysis, copious diarrhoea, and death. Tetanine—C13H30N3O4 —is an alkaloid obtained from cultures of a ba- cillus originating from a wound which had been the cause of death by te- tanus. It forms a deliquescent chloride, and a very soluble chloroplati- nate. The free base or its chloride, when injected into mice or guinea- pigs, causes clonic or tonic convulsions of the greatest intensity, which terminate in death. Mytilitoxine—C6HI5NOa—is an alkaloid obtained from poisonous mussels, which, when administered to animals in small amount, causes the same symptoms as are produced by the mussels. ALBUMINOIDS AND GELATINOIDS. Protein Bodies. The substances of this class are never absent in living vegetable or ani- mal cells, to whose “ life ” they are indispensable. They are as yet the products exclusively of the organized world. Physical Characters.—They are almost all uncrystallizable and incap- able of dialysis. Some are soluble in water, others only in water contain- ing traces of other substances, others are insoluble. Their solutions are all kevogyrous. Some are separated as solids from their solutions, in a permanently modified form, by heat and by certain reagents ; a change called coagulation. When once coagulated they cannot be redissolved. The temperature at which coagulation by heat occurs varies with dif- ferent albuminoids, and is of value in distinguishing them from one an- other. Composition.—They consist of C, N, H, O, and usually a small quantity of S, and form highly complex molecules whose exact composition is un- certain. Of their constitution nothing is definitely known, although there is probability that they are highly complex amides, related to the ureids, and formed by the combination of glycollamine, leucine, tyrosine, etc., with radicals of the acetic and benzoic series. 346 MANUAL OF CHEMISTRY. General Beactions.—They all respond to the following tests ; (1.) A purple red color when warmed to 70° (158° F.) with Millon’s re- agent. The reagent is made by dissolving, by the aid of heat, 1 pt. Hg in 2 pts. HNO„ of sp. gr. 1.42 ; diluting with 2 vols. H20, and decanting after 24 hours. (2.) A yellow color with HN03 ; changing to orange with NH4HO (Xanthoproteic reaction). (3.) A purple color with Pettenkofer’s test (q. v.). (4.) With a drop or two of cupric sulphate solution and liquor potassae a violet color. (5.) A solution of an albuminoid in excess of glacial acetic acid is colored violet and rendered faintly fluorescent by concentrated H.,S04. (6.) With potassium ferrocyanide, in solutions strongly acid with acetic acid, a white ppt. Decompositions.—Dilute acids decompose them into two substances : one insoluble, amorphous, yellowish, called hemiprotein ; the other soluble in water, insoluble in alcohol, faintly acid, called hemialbumin. A pro- longed boiling with moderately concentrated H2S04 decomposes them, forming well-defined substances—glycocol, leucine, tyrosine ; aspartic and glutamic acids. Alkalies dissolve them more or less readily ; on boiling the solution, part of the sulphur is converted into sulphide and hyposul- phite. Their alkaline solutions, when neutralized by acids, deposit Mul- der’s proteine. Concentrated alkalies decompose them into amido-acids. By fusion with alkalies, alkaline cyanides are also produced. When they are heated with caustic baryta and water at 100° (212° F.) carbonate, sul- phate, oxalate, and phosphate of barium are deposited, and CO., and NH. are given off in the same proportions as when urea is similarly treated ; when the temperature is raised, under pressure, finally to 200° (392° F.), a crystalline mass is formed which contains oxalic and acetic acids, a num- ber of amido-acids, aspartic and glutamic acids, and a substance resemb- ling dextrin. Heated with H.,0, under pressure, they are partly dissolved and partly decomposed. A mixture of H2S04 and manganese dioxide, or potassium dichromate, produces from the albuminoids, aldehydes, and acids of the fatty and benzoic series, hydrocyanic acid, and cyanides. When heated under pressure with Br and H.O they yield CO.., oxalic and aspartic acids, amido acids, and bromine derivatives of the fatty and ben- zoic series. Potassium permanganate produces from them urea, C02, XHa and H O. Putrefaction—is a decomposition of dead albuminoid and gelatinous mat- ter, attended by the evolution of fetid gas, and by the appearance of low forms of organized beings (bacteria). That it may occur there must have been contact with air, and there must be presence of moisture and a temperature between 5°-90° (41°-194° F.). It is attended by the breaking down and liquefaction of the material if it be solid ; or its clouding and the formation of a scum upon the sur- face if it be liquid. The products of putrefaction vary with the conditions under which it occurs, the most prominent are : N, H, hydrocarbons, H2S, NH3, C02, certain ill-defined phosphorized and sulphurated bodies, acids of the acetic and lactic series, amido acids, and alkaloidal substances. Under certain imperfectly defined conditions, buried animal matter is converted into a substance resembling tallow, and called adipocere, which consists chiefly of palmitate, stearate, and oleate of ammonium, phosphate and carbonate of calcium, and an undetermined nitrogenous substance. Putrefaction may be prevented by: 0) exclusion of air; (2) removal ALBUMINOIDS AND GELATINOIDS, 347 of water ; (3) maintaining the temperature below 5U (41 i\); (4) the acuon of antiseptics. Antiseptics are substances which prevent or restrain putrefaction. Deodorizers, or air purifiers, are substances which destroy the odorous pro- ducts of putrefaction. Disinfectants are substances which restrain infectious diseases by destroying their specific poisons. Certain substances are antiseptic, deodorant, and disinfectant; such are : chlorine, bromine, iodine, the hypochlorites, and sulphur dioxide ; others lack one of the powers, as the mineral acids and the non-volatile “ disinfectants,” which are antiseptic and disinfectant, but not deodorant. Still others exert but one of the powers, as water and air, which may be mechanical deodorants, but neither disinfectants nor antiseptics. There occurs a decomposition of vegetable tissues under the influence of warmth and moisture, which is known as eremacausis, differing from putrefaction in that the substances decomposed are the carbohydrate in- stead of the azotized constituents, and in the products of the decomposi- tion, there being no fetid gases evolved (except there be simultaneous putrefaction), and the final product is a brownish material (humus or ulmin). Classification.—In the present unsatisfactory state of our knowledge of the chemical constitution of these substances, we can only adopt a tempo- rary classification, based upon their physical and physiological characters. A. Albuminoids : I. Soluble in pure water; coagulated by heat.—The true albumins of the white of egg, serum, and vegetable albumin. II. Insoluble in pure water; soluble in water without alteration in presence of neutral salts, alkalies and acids; and capable of precipitation unchanged from these solutions. 1. Globulins.—Yitellin, myosin, paraglobulin, fibrinogen. 2. Animal caseins.—Milk casein, serum casein. 3. Vegetable caseins.—Gluten casein, legumin, conglutin. 4. First terms of decomposition of the albuminoids by acids, alkalies, and cryplolytes.—Albuminates (so called), acid albumin, syntonin, liemiprotein, peptone. III. Insoluble in water and, only soluble after decomposition. Cannot be separated without alteration from their solutions in acids and alkalies.—Gluten fibrin, gliadin, mucedin. IY. Coagulated.—Coagulated albumin and fibrin. Y. Amyloid matter.—Lardacein. B. Gelatinoids : ■ I. Collagenes.—Collagen, elastin, ossein and its derivatives, chondngen ? chondrin ? gelatin, keratin. II. Mucilaginous bodies.—Mucin, paralbumin, colloidin. Albuminoids. X.—Egg albumin exists in solution, imprisoned in a network of deli- cate membranes, in the white of egg. It is obtained in an impure condi- tion by cutting the whites of eggs with scissors, expressing through linen, diluting with an equal volume of water, filtering and concentrating the filtrate at a temperature below 40° (104' F.); mineral salts, which adhere to it tenaciously, are separated by dialysis. It seems to be a mixture of two different substances, one of which coagulates at 63° (145 . 4 F.), and has the rotary power [a]D =—4:3 d ; the other coagulates at i4 (105 .2 F.), 348 MANUAL OF CHEMISTRY. and has the value of [a]D = — 26°. Its solutions are not precipitated by a small quantity of HC1, but an excess of that acid produces a deposit which is difficultly soluble in HC1, H.,0, and salt solution. Its characteristic reaction is that it is coagulated by agitation with ether. Serum-albumin exists in blood-serum, chyle, lymph, pericardial fluid, the fluids of cysts and of transudations, in milk and, pathologically, in the urine. It is best obtained from blood-serum, after removal of para- globulin (q. u.), by a tedious process, and only then in a state of doubtful purity. It is less abundant in the blood of some animals than paraglobu- lin, but more abundant in that of man. Solutions of serum-albumin are lsevogyrous [«]„ = — 56° ; they are not precipitated by CO„, by acetic or orthopkosphoric acid, by ether or by magnesium sulphate. They are precipitated by mineral acids, tannic acid, metapliosplioric acid, and most metallic salts. When heated they become opalescent at G0° (140° F.), and coagulate in the flocculent form at 72°- 753 (161°.6-167° F.). Detection and Determination of Albumin in Urine.—If the urine be not perfectly clear it is filtered, if this do not render it perfectly transparent, it is treated with a few drops of magnesia mixture (p. 85 note), and again filtered. The filtrate, if alkaline, is rendered just acid by adding acetic acid guttatim (nitric acid should not be used, and the acidu- lation of alkaline urine is imperative). The urine is now heated to near boiling, and if a cloudiness or precipitate be formed. HN03 is added slowly to the extent of about 10 drops. If heat produce a cloudi- ness, which clears up completely on addi- tion of HNOa, it is due to an excess of earthy phosphates. If a cloudiness pro- duced by heat do not clear up (it may in- crease) on addition of HNOa, it is due to albumin. Small quantities of albumin may some- times be better detected by Heller’s test: A layer of HN03 is placed in a test-tube, which is then held at an angle and the urine allowed to How slowly upon its surface (Fig. 40) so as to form a distinct layer, with the minimum of mixing of the two liquids ; the test-tube is then brought to the vertical slowly, and the point of junction of the two liquids examined against a dark background. If albumin be present a white, opaque band, whose upper and lower borders are sharply defined, will be seen at the line of junction of the two liquids. "When urates are present in excess, a white band will be observed, but its position will be rather above the line of junction, and its upper border will not be sharply defined, but gradually diminish in density from below upward. In noil-albuminous urines there is usually a darkening, but never an opacity at the line of junction. Fig. 40. Quantity.— The only method of determining the quantity of albumin in urine, with an approach to accuracy, is gravimetric : 20-50 c.c. (5.4-10.5 fl 3 ) of the filtered urine (according as the qualitative testing shows albumin to be present in large or small quantity) are slowly heated over the water-bath, and, as the boiling temperature is approached, 3-4 drops of acetic acid are added. After the urine has boiled for a few moments, it is thrown upon a filter. The coagulum is washed with boiling HqO. then with IIA) acidulated with NOsH, then with alcohol and finally with ether. By these washings impurities are removed, and ti e albumin is caused to contract firmly, so that it can be easily detached and transferred to a weighed watch- glass ; upon this it is dried at 115° ( 230° F.) and the whole weighed. The difference between the last weight and that of the watch-glass, is the weight of dry albumin in the volume of urine used. ALBUMINOIDS AND GELATINOIDS. Vegetable albumin—exists in solution in all vegetable juices, and forms the most valuable constituent of those vegetables which are used as food. It is coagulated from its solutions at 61°-G3° (141°.8-145°.4 F.), and by nearly all acids. II.—Vitelin exists in the yolk of egg and in the crystalline lens. It is soluble in dilute solution of sodium chloride, from which it is precipir tated by excess of H.,0; by heating to 75°-80° (1G7°-176° F.); and by alcohol. It is not precipitated by solid sodium chloride. It dissolves in weak alkaline solutions without alteration and in very dilute HC1 (1-1000), by which it is quickly converted into syntonin. Myosin—is one of the principal constituents of the muscular fibre in rigor mortis. It is a faintly yellow, opalescent, distinctly alkaline liquid, which, when dropped into distilled H.,0, deposits the myosin in globular masses, while the H.,0 assumes an acid reaction. It is insoluble in H.,0, easily soluble in dilute salt solution, from which it is precipitated by the addition of solid sodium chloride, or by a heat of 55°-G0° (131°-140° F.). Very dilute HC1 dissolves and converts it into syntonin. Paraglobuiin.—This substance has been described by various authors under the names: plasmine (Denis), serum casein (Panum j, serum glob- uline, fibrino-plastic matter (Schmidt), serin (Denis). It exists in blood- serum, in pericardial fluid, hydrocele fluid, lymph and chyle, from which it is obtained by diluting with 10-15 volumes of ice-cold HaO, treatment of the solution with strong current of C02, and washing the collected deposit with H O as long as a portion of the filtrate precipitates with acetic acid and potassium ferrocyankle, or with silver nitrate. It is a granular substance, which gradually becomes more compact; insoluble in HO, sparingly soluble in H O containing C03; soluble in dilute alkalies, in lime-water, in solutions of neutral alkaline salts, in dilute acids. Its solution in very dilute alkaline fluids is perfectly neutral and is not coagulated by heat, except after faint acidulation with acetic or mineral acids; it is precipitated by a large volume of alcohol ; its solutions are also precipitated incompletely by dissolving sodium chloride in them to saturation, and completely by similar solution of magnesium sulphate ; this last method of precipitation is used for the separation of paraglobuiin from serum-albumin (see Fibrin). Fibrinogen—after the separation of paraglobuiin from blood-plasma, as described above, if the liquid be still further diluted and again treated with CO,,, a substance is obtained which, although closely resembling paraglobuiin in many characters, is distinct from it, and, unlike paraglob- uiin, it cannot be obtained from the serum separated from coagulated blood. Paraglobuiin and fibrinogen are both soluble in a solution of sodium chloride containing 5-8 per cent, of the salt ; when the degree of concen- tration of the salt solution is raised to 12-1G per cent., the fibrinogen is precipitated, while the paraglobuiin remains in solution and is only pre- cipitated, and then incompletely, when the percentage of salt surpasses twenty (see Fibrin). Milk casein—the most abundant of the albuminoids of the milk of mammalia, closely resembles alkali albuminates, with which it is probably identical, as the main point of distinction has been found to be without significance. Unlike pure alkali albuminates, casein is coagulated from its solution by rennet (the product of the fourth stomach of the calf) at 40" (104° F.); but it has been found that alkali albuminate is also so coagu- 350 MANUAL OF CHEMISTRY. lated when milk-sugar and fat are added to the solution. Milk. —The secretion of the mammary gland is water holding in solu- tion casein, albumin, lactose, and salts ; and fat in suspension. Cream consists of the greater part of the fat, with a small proportion of the other constituents of the milk. Skim milk is milk from which the cream lias been removed. Buttermilk is cream from which the greater part of the fat has been removed, and consequently is of about the same composition as skim milk. The composition of milk differs in animals of different species : Human. Cow. Goat. Sheep. Ass. Mare. Cream. Condens- ed milk. Water.... 88.35 84.28 86.85 83.30 89.01 90.45 45.99 25.68 Solids.... 11.65 15.72 13.52 16.60 10.99 9.55 54.01 74.32 Casein ... Albumin.. i 3-i5-( 3.57 0.78 2.53 1.26 | 5.73 3.57 2.53 6.3a 16.83 Fat 3.87 6.47 4.34 6.05 1.85 1.31 43.97 10.27 Lactose .. 4.37 4.34 3.78 3.96 j- 5.05 ( 5.43 3.28 44.33* Salts 0.26 0.63 0.65 0.68 { 0.29 0.42 2.80 * Including 28.08 parts of cane-sugar. The composition of cows’ milk varies considerably according to the age, condition, breed and food of the cow ; to the time and frequency of milking ; and to whether the sample examined is from the first, middle, or last part of each milking. Cows’ milk is very frequently adulterated, both by the removal of the cream and the addition of water. For ordinary purposes, the purity of the milk may be determined by observing the sp. gr. and the percentage of cream by the lactometer and creamometer, neither of ivhich, used alone, affords indications which can be relied upon. The sp. gr. should be ob- served at the temperature for which the instrument is made, as in a com- plex fluid such as milk no valid correction for temperature is practical; it ranges in pure milk from 1027 to 1034, it being generally the lower in milk which has been watered, and in such as is very rich in cream, and the higher the less cream is present. The average sp. gr. is 1030 ; the average percentage of cream 13. The percentage of cream is determined by the creamometer: a glass tube about a foot long and half an inch in diameter, the upper fifth (ex- cluding about an inch from the top) being graduated into hundredths of the whole, the 0 being at the top. To use it, it is simply filled to the 0 with the milk to be tested, set aside for twenty hours and the point of sep- aration between milk and cream read off. It should be above eight per cent. This method of determining the purity of milk, although sufficient for ordinary purposes, should not be considered as affording evidence upon which to base legal pi'oceedings ; in such cases nothing short of a chemical determination of the percentage of fats, and of solids not fat, should be accepted as evidence of the impurity of milk. Serum-casein is a substance obtained from blood-serum diluted with 10 volumes of H20, freed from paraglobulin by CO„, and from albumin by acetic acid and heat. It is insoluble in salt solutions, slowly soluble in a one per cent, solution of sodium hydrate. Such a solution is partially pre- ALBUMINOIDS AND GELATINOIDS. 351 cipitated by CO,, almost completely by acetic acid, and completely by beat- ing with excess of powdered sodium chloride ; incompletely soluble in di- lute HC1. Gluten-casein.—That portion of crude gluten (a soft, elastic, grayish, material best obtained from hour) which is insoluble in alcohol, hot or cold ; Legumin—a sparingly soluble albuminoid obtained from peas, beans, etc.; and Conglutin—a substance closely related to legumin and to gliadin, but differing from them in some characters, obtained from almonds, are three vegetable albuminoids resembling casein. They are insoluble in pure water, readily soluble in dilute alkaline so- lutions, from which they are precipitated by acids and by rennet. Alkali albuminates—proteins of Hoppe Sevier—are formed when an albuminoid is dissolved in concentrated solutions of potassium and sodium hydrates ; it is very probable that they are identical with serum and milk- casein. Acid albumins—are substances obtained by precipitating solutions of albuminoids by the simultaneous addition of an acid and a large quan- tity of a neutral salt; they vary exceedingly in composition and proper- ties. Syntonin—Parapeptone—is extracted from contractile tissues. The same substance is formed by the action of dilute acids upon the albumi- noids, and as the first product of the action of the gastric juice, or of mix- tures of pepsin and dilute acid upon albuminoids. It resembles serum casein closely, the only divergence in their properties being that syntonin is much more readily soluble in a 0.1 per cent, solution of HC1, and in faintly alkaline liquids. Peptone—Albuminose—is the product of the action of the gastric and pancreatic juices upon albuminoids during the process of digestion. It is soluble in H,0, insoluble in alcohol and in ether. Its watery solution is neutral, not precipitable by acids or alkalies, or by heat when faintly acid. Alcohol precipitates it in white, casein-like flocks, which, if slowly heated to 90° (194° F.) while still moist form a transparent, yellowish liquid, and, on cooling, an opaque, yellowish, glassy mass. It has a greater power than other albuminoids of combining with acids and bases. The most important character of peptone, in which it differs from other albuminoids, is that it is readily dialysable. Its presence in the blood has not been demonstrated, and it is probable that immediately upon its en- trance into the circulation it is converted into albuminoids resembling, yet differing from, those from which it was derived. Peptone is produced by the action of many chemical reagents upon albuminoids; and also as one of the first products of putrefaction. When produced by putrefaction, or by artificial digestion, it is accom- panied by peptotoxine, a crystallizable and actively poisonous alkaloidal substance. It has been claimed that the gastric digestion of different albuminoids produces, not a single substance, but a distinct peptone for each albumin- oid. If such be the case, and the present state of our knowledge does not permit of a definite answer to the question, these bodies are very closely related. Peptone responds to the general reactions for the albuminoids (see p. 346), from which it may be distinguished by the biuret reaction. If a mere trace of CuS04solution be added to a solution of peptone and then KHO or NaHO solution, a purple or reddish violet color is produced. A similar appearance is produced with acid albumins. 352 MANUAL OF CHEMISTRY. IV. —Coagulated albumins—are obtained, as described above, from the soluble varieties by the action of acids, heat, alcohol, etc. They are insoluble in water, alcohol, solutions of neutral salts ; difficultly soluble in dilute alkaline solutions. In acetic acid they swell up and dissolve slowly; from this solution they are precipitated by concentrated salt solution. Concentrated HC1 dissolves them with formation of syntonin. By the ac- tion of gastric juice, natural or artificial, they are converted first into syn- tonin, then into peptone. Fibrin—is obtained when blood is allowed to coagulate or is whipped with a bundle of twigs. When pure it is at first a gelatinous mass, which contracts to a white, stringy, tenacious material, made up of numerous minute fibrils ; when dried it is hard, brittle, and hygroscopic. It is in- soluble in water, alcohol, ether ; in dilute acid it swells up and dissolves slowly and incompletely. When heated with water to 72° (1G1 .G F.), or by contact with alcohol, it is contracted, and is no longer soluble in dilute acids, but soluble in dilute alkalies. In solutions of many neutral salts of G-10 per cent., it swells up and is partially dissolved ; from this solu- tion it separates on the addition of water, or upon the application of heat to 73° (1G3°.4 F.), or by acetic acid or alcohol. Moist fibrin has the property of decomposing oxygenated water with copious evolution of oxygen. Fibrin does not exist as such in the blood, and the method of its form- ation and of the clotting of blood has been the subject of much experiment and argument ; nor can the question be said to be definitely set at rest. In the light of the researches of Denis, Schmidt, and especially of Harnmar- sten, it may be considered as almost proven that fibrin is formed from fibrinogen under favorable circumstances, and by a transformation which is not yet understood. Whether paraglobulin plays any part directly in the formation of fibrin or not, is still an open question. V. —Amyloid—is a pathological product, occurring in fine grains, re- sembling starch-granules in appearance, in the membranes of the brain and cord, in waxy and lardaceous liver, and in the walls of the blood-ves- sels. Its composition is that of the albuminoids, from which it differs in being colored red by iodine ; violet or blue by iodine and H,S04. Soluble in HC1 with formation of syntonin ; and in alkalies. It is not at- tacked by the gastric juice, and is not as prone to putrefaction as the other albuminoids. Gelatinoids. I.—Collagen.—Bony tissue is made up mainly of tricalcic phosphate, combined with an organic material called ossein, which is a mixture of collagen, elastin, and an albuminoid existing in the bone-cells. Collagen also exists in all substances which, when treated with H.,0, under the in- fluence of heat and pressure, yield gelatin. It is insoluble in cold H.,0, but by prolonged boiling is converted into gelatin, which dissolves. It is dissolved by alkalies. Gelatin—obtained as above, from ossein, exists in the commercial pro- duct of that name, and in a less pure form in glue. When pure it is an amorphous, translucent, yellowish, tasteless substance, which swells up in cold H20, without dissolving, and forms, with boiling H„0, a thick, sticky solution, which on cooling becomes, according to its concentration, a hard glassy mass or a soft jelly—the latter even when the solution is very dilute. It is insoluble in alcohol and ether, but soluble, on warming, in glycerin; ANIMAL CRYPTOLYTES the solution in the last-named liquid forms, on cooling, a jelly which has recently been applied to various contrivances for copying writing. A film of gelatin impregnated with potassium dichromate becomes hard and insol- uble on exposure to sunlight. Chondrin is the name given to a substance obtained from cartilaginous tissue and supposed to be distinct from gelatin. It is probably a mixture of gelatin and mucin. filastin—is obtained from elastic tissues by successive treatment with boiling alcohol, ether, water, concentrated acetic acid, dilute potash solu- tion and water. It is fibrous, yellowish ; swells up in water and becomes elastic; soluble with a brown color in concentrated potash solution. It contains no S, and on boiling with H.,801 yields glycol. Keratin—is the organic basis of horny tissues, hair, nails, feathers, whalebone, epithelium, tortoise-shell, etc. It is probably not a distinct chemical compound, but a mixture of several closely related bodies. II.—Mucin—is a substance containing no S and existing in the differ- ent varieties of mucus, in certain pathological fluids, in the bodies of mol- luscs, in the saliva, bile, connective tissues, etc. Its solutions, like the fluids in which it occurs, are viscid. It is precipitated by acetic acid and by HN03, but is dissolved by an excess of the latter; it dissolves readily in alkaline solutions, and swells up in HaO, with which it forms a false solution. It is not coagulated by heat. ANIMAL CRYPTOLYTES. Soluble Animal Ferments. Under this head are classed substances somewhat resembling the al- buminoids, of unknown composition, occurring in animal fluids, and having the power of effecting changes in other organic substances, the method of whose action is undetermined. (See p. 182.) Ptyalin—is a substance occurring in saliva, and having the power of converting starch into dextrin and a sugar resembling glucose (ptyalose), in liquids having an alkaline, neutral, or faintly acid reaction. Pepsin—is the cryptolyte of the gastric juice. Attempts to separate it without admixture of other substances have hitherto proved fruitless ; nevertheless, mixtures containing it and exhibiting its characteristic prop- erties more or less actively have been obtained by various methods. The most simple consists in macerating the finely divided mucous membrane of the stomach in alcohol for 48 hours, and afterward extracting it with gly- cerin ; this forms a solution of pepsin, which is quite active and resists putrefaction well, and from which a substance containing the pepsin is precipitated by a mixture of alcohol and ether. If pepsin be required in the solid form, it is best obtained by Briicke’s method. The mucous membrane of the stomach of the pig is cleaned and detached from the muscular coat by scraping ; the pulp so obtained is di- gested with dilute phosphoric acid at 38° (100°.4 F.), until the greater part of it is dissolved ; the filtered solution is neutralized with lime-water ; the precipitate is collected, washed with H20, and dissolved in dilute HC1; to this solution a saturated solution of cholesterin, in a mixture of 4 pts. alcohol and 1 pt. ether, is gradually added ; the deposit so formed is repeatedly shaken with the liquid, collected on a filter, washed with H20 and then with dilute acetic acid, until all HC1 is removed ; it is then 354 MANUAL OF CHEMISTRY. treated with ether and H.,0 : the former dissolves cholesterin and is poured off, the latter the pepsin ; after several shakings with ether the aqueous liquor is evaporated at 38° (100°.4 F.), when it leaves the pepsin as an amorphous, grayish-white substance ; almost insoluble in pure H.,0, readily soluble in acidulated H O ; probably forming a compound with the acid, which possesses the property of converting albuminoids into peptone. The so-called pepsma porci is either the calcium precipitate obtained as described in the first part of the above method or, more commonly, the mucous membrane of the stomach of the pig, scraped off, dried, and mixed with rice-starch or milk sugar. Pancreatin.—Under this name, substances obtained from the pancre- atic secretion, and from extracts of the organ itself, have been described, and to some extent used therapeutically. They do not, however, contain all the cryptolytes of the pancreatic juice, and in many instances are inert albuminoids. The actions of the pancreatic juice are : (1) it rapidly con- verts starch, raw or hydrated, into sugar ; (2) in alkaline solution—its natural reaction—it converts albuminoids into peptone ; (3) it emulsifies neutral fats; (4) it decomposes fats, with absorption of H20 and libera- tion of glycerin and fatty acids. The pancreatic secretion probably contains a number of cryptolytes— certainly two. The one of these to which it owes its peptone-forming power has been obtained in a condition of comparative purity by Kiihne, and called by him trypsin ; in aqueous solution it digests fibrin almost immediately, but it exerts no action upon starch. The diastatic (sugar-forming) cryptolyte of the pancreatic juice has not been separated, although a glycerin extract of the finely divided pancre- atic tissue contains it, along with trypsin. ANIMAL COLORING MATTERS. Haemoglobin and its Derivatives—Haemato-crystallin.—The color- ing matter of the blood is a highly complex substance, resembling the albuminoids in many of its properties, but differing from them in being crystallizable and in containing iron. Haemoglobin exists in the red-blood corpuscles in two conditions of oxidation ; in the form in which it exists in arterial blood it is loosely com- bined with a certain quantity of oxygen, and is known as oxyhcemoglobin. The mean of many nearly concording analyses shows its composition to be CB00H960NJB4FeS3OI79. When obtained from the blood of man and from that of many of the lower animals, it crystallizes in beautiful red prisms or rhombic plates ; that from the blood of the squirrel in hexagonal plates ; and that from the guinea-pig in tetraliedra. The crystals are always doubly refracting. It may be dried in vacuo at 0° (32° F.); if thoroughly dried below 0° (32° F.), it may be heated to 100° (212° F.) without decomposition, but the presence of a trace of moisture causes its decomposition at a much lower temperature. Its solubility in water varies with the species of animal from whose blood it was obtained ; thus, that from the guinea-pig is but sparingly soluble, while that from the pig is very soluble. It is also dissolved unchanged by very weak alkaline solutions, but is decomposed by acids or salts having an acid reaction. Haemoglobin, or reduced hcemoglobm, is formed from oxyhemoglobin in ANIMAL COLOK1NG MATTE I tlie economy during the passage of arterial into venous blood; and by tlie action of reducing agents, or by boiling its solution at 40' (104' F.) in tbe vacuum of the mercury pump. Oxylnemoglobin is of a much brighter color than the reduced, and has a different absorption spectrum. The spectrum of oxylnemoglobin varies with the concentration. In concentrated solutions the light is entirely absorbed, in more dilute solutions the spectrum 10, Fig. 14, is observed, and in still further dilutions 11, Fig. 14 ; in which the band at D is nar- rower, darker, and more sharply defined than the other. In highly diluted solution the band at D is alone visible. The spectrum of haemoglobin consists of a single band much broader and fainter than either of the oxy- lnemoglobin bands (12, Fig. 14). Hemoglobin, in contact with O or air, is immediately converted into oxylnemoglobin. With CO it forms a compound resembling oxyhemoglo- bin in the color of its solution, but in which the CO cannot be replaced by O; for which reason hemoglobin, once combined with CO, becomes per- manently unfit to fulfil its function in respiration (see p. 234). When a solution of oxyhemoglobin is boiled, it becomes turbid, and a dirty, brownisli-red coagulum is deposited ; the hemoglobin has been decomposed into an albuminoid (or mixture of albuminoids), called by Preyer global, and hcematin. The latter, at one time supposed to be the blood-coloring matter, is a blue-black substance, having a metallic lustre and incapable of crystallization ; it is insoluble in water, alcohol, ether, and dilute acids; soluble in alkaline solutions. It has the composition Cc.H70 N.Fe.,O10. Its alkaline solutions exhibit the spectrum 13, Fig. 14. Although itself uncrystallizable, Inematin combines with HC1 to form a compound which crystallizes in rhombic prisms, and which is identical with the earliest known crystalline blood-pigment, hcemin, or Teichmann's crystals. When reduced haemoglobin is decomposed as above, in the absence of oxygen, haematin is not produced, but a substance identical with that called reduced hcematin, and called by Hoppe-Seyler hcemocromogen ; whose spectrum is shown in 14, Fig. 14. If a solution of haemoglobin be exposed for some time to air it changes in color from red to brownish, and assumes an acid reaction ; it then ex- hibits the spectrum 15, Fig. 14, due to the production of methcemoglobin, probably a stage in the conversion of lnemoglobin into lirematin and glob in. Biliary pigments.—There are certainly four, and probably more, pigmentary bodies obtainable from the bile and from biliary calculi, some of which consist in great part of them. Bilirubin—C^Hg^O,,—is, when amorphous, an orange-yellow powder, and when crystalline, in red rhombic prisms. It is sparingly soluble in H20, alcohol, and ether ; readily soluble in hot chloroform, carbon disul- phide, benzene, and in alkaline solutions. When treated with HNO, con- taining nitrous acid, or with a mixture of concentrated HN03 and H.,S04, it turns first green, then blue, then violet, then red, and finally yellow. This reaction, known as Gmelin’s, is very delicate, and is used for the de- tection of bile-pigments in icteric urine and in other fluids. Biliverdin—CsaH36N408—is a green powder, insoluble in H O, ether, and chloroform ; soluble in alcohol and in alkaline solutions. It exists in green biles, but its presence in yellow biles or biliary calculi is doubtful. It responds to Gmelin’s test. In alkaline solution it is changed after a time into biliprasin. Btt.tfttsctx—O H N P4—obtained in small quantity from human gall- stones, is an almost black substance, sparingly soluble in H.,0, ether, and 356 MANUAL OF CHEMISTRY. chloroform ; readily soluble in alcohol and in dilute alkaline solutions Its existence in the bile is doubtful. Biliprasin—OK)H22N2O0(?)—exists in human gall-stones, in ox-gall, and in icteric urine. It is a black, shining substance, insoluble in H..O, ether, and chloroform ; soluble in alcohol and in alkaline solutions. Urobilin — Hydrobilirubin — C:)„H40N4O..—Under the name urobilin, Jaffe described a substance which he obtained from dark, febrile urine, and which he regarded as the normal coloring matter of that fluid ; subse- quently he obtained it from dog’s bile and from human bile, from gall- stones and from faeces. Stercobilin, from the faeces, is identical with urobilin. Urinary pigments.—Our knowledge of the nature of the substances to which the normal urinary secretion owes its color is exceedingly unsatis- factory. Jaffe in his discovery of urobilin shed but a transient light upon the question, as that substance exists in but a small percentage of normal urines, although they certainly contain a substance readily convertible into it. Besides the substance convertible into urobilin, and sometimes urobilin itself, human and mammalian urines contain at least one other pigmentary body, uroxanthin, or indigogen. This substance was formerly considered as identical with indican, a glucoside existing in plants of the genus Isatis, which, when decomposed, yields, among other substances, indigo-blue. Uroxanthin, however, differs from indican in that the former is not de- composed by boiling with alkalies, and does not yield any glucose-like substance on decomposition ; the latter is almost immediately decom- posed by boiling alkaline solutions, and, under the influence of acids and of certain ferments, yields, besides indigo-blue, indiglucin, a sweet, non- fermentable substance, which reduces Fehling’s solution. Uroxanthin is a normal constituent of human urine, but is much in- creased in the first stage of cholera, in cases of cancer of the liver, Addi- son’s disease, and intestinal obstruction. It has also been detected in the perspiration. In examining the color of urine it should be rendered strongly acid with HN03 or HC1, and allowed to stand six hours to liberate combined pig- ment, and then examined by transmitted light in a beaker three inches in diameter. Melanin is the black pigment of the choroid, melanotic tumors, and skin of the negro ; and occurs pathologically in the urine and deposited in the air-passages. PART III. LABORATORY TECHNICS. Chemistry is essentially a science of experiment; and not only is a knowledge of its truths much more rapidly and easily acquired by the stu- dent through the actual performance of experiment, than by any amount of reading or attendance upon illustrated lectures; but it is even doubtful whether a thorough knowledge of the facts and theories of the science can be obtained in any other way than by personal observation. A description of the various manipulations of the general chemical la- boratory would fill volumes. A short account of the more prominent of those required in a study of rudimentary chemistry, and in those pro- cesses of analysis which are likely to be of service to the physician will, we believe, not be out of place in a work of this nature. GENERAL RULES. “ Cleanliness,” said John Wesley, “ is next to godliness.” The chemist, whatever his supply of godliness, must be thoroughly imbued with the spii'it of cleanliness ; not so much as regards himself, for he who fears to soil his fingers is not of the material whereof chemists are made, but as regards the vessels and reagents which are his tools. Any substance for- eign to the matter under examination and the reagents used, whatever be its nature, is dirt to the chemist. Glass vessels should always be cleaned as soon as possible after using, as foreign substances are much more readily removed then than after they have dried upon the glass. Usually rinsing with clear water, and friction with a probang or bottle brush is sufficient; greasy and resinous substances may be removed with KHO solution ; and other adherent de- posits usually with HC1 or HNOa; the alkali or acid being removed by clear water. After washing, the vessels are drained upon a clean surface, and are not to be put away unless perfectly bright. Order and system are imperative, especially if several operations are conducted at the same time. If there be “a place for everything, and everything in its place,” much time will be spared. If a process be of such a nature that it requires a number of vessels, each vessel should be numbered with a small gum label, and the notes of the operation should indicate the stage of the process in each vessel. The habit of taking full and systematic notes of experiments and analyses in a book kept especially for the purpose, is one which the stu- dent cannot contract too early. He will be surprised, in looking over and 358 MANUAL OF CHEMISTRY. comparing his notes, at the amount of information he will have collected in a short time ; much of which, had the memory been trusted to, would have been lost. REAGENTS. The stock of reagents required varies, of course, with the nature of the work to be done ; from the small number required in urinary analysis, to the array on the shelves of a fully appointed analytical laboratory. The liquid reagents and solutions should always be kept in glass-stop- pered bottles (the 44 3 bottles, with labels blown in the glass, serve very well). The solid reagents may be kept in cork-stoppered or, preferably, glass-stoppered bottles. The ordinary glass stoppers should never be laid upon the table, lest they take up particles of foreign matter and contami- nate the contents of the bottle ; but should be held between the third and little fingers of the left hand. The reagents required for ordinary urinary analysis are: Nitric acid, Sulphuric acid, Acetic acid, Potassium hydrate, Ammonium hydrate, Cupric sulphate, Fehling's solution, Test papers. Those required for ordinary qualitative analysis are : Hydrochloric acid, Nitric acid, Sulphuric acid, Acetic acid, Hydrogen sulphide, Ammonium sulphide, Ammonium hydrate, Potassium hydrate, Ammonium chloride, Ammonium carbonate, Ammonium oxalate, Sodium carbonate, Hydro-disodic phosphate, Potassium ferrocyanide, Potassium ferricyanide, Potassium sulphocyanate. Potassium carbonate, Potassium chromate, Barium chloride, Calcium sulphate, Magnesium sulphate, Cupric sulphate, Argentic nitrate. Mercuric chloride, Plumbic acetate, Ferric chloride, Platinic chloride. The chemicals must be C. P. (= chemically pure); and the solutions must be made with distilled H O. It is well to put corresponding num- bers on each bottle and stopper to prevent their becoming mixed in cleaning. GLASS TUBING. The tubing used in making all usual connections and apparatus is the soft German or American tubing. When the tube is to be strongly heated, Bohemian tubing must be used. The fashioning of tubing of the diameter generally used for gas connections is a simple matter. (jutting into aesirea lengms is ac- complished by making a scratch with a triangular file at the desired point; holding the tube as shown in Fig. 41; and partly drawing, and partly bending it. Larger glass surfaces may be cut in any required direction, by first making a deep scratch with the file ; starting the break by bringing in contact with scratched spot a piece of red-hot glass tubing; and leading the break in the desired direction by applying a heated piece of j-incli iron wire, as shown in Fig. 42. Cut ends of tubing should always be rendered smooth by heating them to in- cipient fusion. Fig. 41. LABORATORY TECHNICS. 359 Bending is done by heating the tube at the desired point in an ordinary gas flame (not a blow-pipe flame), without rotating it, until softened; re- moving from the flame and bending toward that surface which was near- est the oififice of the gas jet. Fig. 42. Closing.—For this and other operations with glass tubing, the glass- blower’s flame, obtained with a burner (Fig. 43) which permits of the in- jection of air into the gas flame, is required. To make a test-tube a piece of tubing of the length of two test-tubes is drawn out at the middle (see below). The small end of each piece is then heated and the superfluous glass removed by a warm glass rod, which is brought into contact for an instant and then drawn away. The closed end is then heated during rotation until soft, and rendered hemispherical by gently blowing into the open end. The open end is then heated and while hot formed into a lip by a circu- lar motion with a hot iron ware. Draining out consists in heating the tube at the point desired, during rotation, and drawing it apart after removal from the flame. Joining.—Two pieces of tubing of different diame- ters may be joined end for end if they be of the same kind of glass. The ends of each are closed, heated, and blown out into thin bulbs. The bulb is then broken off, the ends heated, pressed firmly together, and re-heated during alternate pressure and drawing apart, and gentle blowing into one end while the other is closed, until an even joint is obtained. Stirring rods are made by cutting glass rods to the required length and rounding the ends by fusion. Fig. 43. COLLECTION OF GASES. Gases are collected over the pneumatic trough, by displacement of air ; or over the mercurial trough. In the pneumatic trough (Fig. 44) gases are collected over water in bell jars filled with that liquid. This method of collection can only be used for insoluble or sparingly soluble gases ; and if heat have been used in the generation of the gas the disengagement tube must be removed from the water before the heat is discontinued, to avoid an explosion. MANUAL OF CHEMISTRY. Soluble gases are collected over mercury or by upward or downward displacement of air, according as they are without action on Hg, or heavier or lighter than air. Fig. 44. SOLUTION. As the particles of liquids can be brought into closer contact than those of solids, reactions are usually facilitated by bringing the reagents into solu- tion or into fusion. At a given temperature solution of a solid is more rapid the greater the surface exposed to the solvent, i.e., the greater the degree of subdivision. Ordinary salts are ground to powder in Wedgwood or glass mortars. Very hard sub- stances are first coarsely powdered in steel mor- tars and then finely ground in agate mortars. Soft substances are best subdivided either by hashing, as in the case of muscular tissue, or by forcing through the meshes of a fine sieve, as in the case of white of egg, brain tissue, etc. When only certain constituents of the sub- stance are to be dissolved, ’percolation may be resorted to. The substance to be extracted is packed in a percolator in such a manner that the extracting liquid filters through it slowly. When the solvent is a volatile liquid—ether, chloroform, carbon disulphide—extraction is best accomplished in an apparatus such as that shown in Fig. 45, in which the liquid is boiled in A; the vapor passing through a, b, is liquefied in the condenser and flows back over the substance in B. The extract collects in A. Fig. 45. LABORATORY TECHNICS. 361 PRECIPITATION—DECANTATION—FILTRATION—WASHING. When the conversion of an ingredient of a solution into an insoluble compound, and its separation from the liquid are desired, both the liquid and the reagent should be in clear solution, and the latter should be added to the former, which has been warmed. The vessel is then set in a warm place until the precipitate has subsided, a few drops of the precipitant are added to the clear liquid, and if no cloudiness be produced the precipita- tion is complete. Precipitation should be effected in Erlenmeyer fiasks (Fig. 46) or in precipitating jars (Fig. 47) that the precipitate may not collect on the sides, and may be readily detached by the wash-bottle. Precipitates are separated from the liquid in which they have been formed by decantation ox filtration. Fig. 47. Eig. 48. Decantation consists in allowing the precipitate to subside and pouring off the supernatant hquid ; it should always be employed as a preliminary to filtration, and is sometimes used exclusively, wdien the precipitate is washed by repeatedly pouring on clear wTater and decanting it until it no longer contains any solid matter. 362 MANUAL OF CHEMISTRY. In pouring liquid from one vessel to another it should be guided by a glass rod, as shown in Fig. 48 ; the outer surface of the lip of the pouring vessel having been slightly greased. Filtration is resorted to more frequently than decantation. Filters are made from muslin, paper, asbestos, or glass wool. Muslin filters are only used for coarse filtration. Paper filters are the most frequently used. For coarse work the ordinary gray or German white paper is used ; but for analytic work a paper which leaves but a small amount of ash is required ; the best now in the market is Schleicher & Schull’s Nos. 597 and 589. The filter should be taken of such size that when folded it will be smaller than the funnel in which it is to rest. It is folded across one diameter, and again over the radius at right angles to the first diameter ; one of the four layers of paper, then seen at the circular portion of the filter, is separated from the other three, in such a way as to form a cone. The filter so formed is brought into the Fig. 49. Fig. 50. funnel, and, while held in position by a finger-nail over one of the folds, is wetted with water from the wasli-bottle. After the paper has been brought in contact with the funnel by a glass rod, the liquid to be filtered is intro- duced, care being had not to overflow the filter, and to allow any superna- tant liquid in the precipitating jar to pass through, before bringing the precipitate itself upon the filter. Funnels used for filtering should have an angle of 60°, and a long stem, the point of which is ground off at an acute angle. Asbestos and glass wool plugs loosely introduced into the stem of a fun- nel, are used in filtering such liquids as would destroy paper. For filtrations which take place slowly the filter-pump is now exten- sively used. It is simply an appliance for exhausting the air in the stem of the funnel, and thus taking advantage of atmospheric pressure. A sim- ple and effective form of pump is that shown in Fig. 49, in which the water (under 10 feet or more of pressure) enters at a and aspirates the air from b through c. When the pump is used a small cone of platinum LABORATORY TECHNICS. 363 foil must be placed at the apex of the funnel to support the point of the filter, which would otherwise be ruptured. When the precipitate has been collected upon the filter, it must be icashed until free from extraneous matter. This is effected by blowing into the tube a of the wash-bottle, Fig. 50, while the end of the tube b is held so as to deliver a gentle stream into the filter ; care being had that the precipi- tate is not lost by spurting, overflowing, or creeping up the sides of the funnel. The completeness of the washing is not to be guessed at but is to be judged by adding reagents, suitable to the case, to portions of the fil- trate until they fail to cause a cloudiness. EVAPORATION—DRYING—IGNITION. Evaporations are usually conducted on the sand- or water-bath. The sand-bath is simply a flat, iron vessel, filled with sand and heated. By its use the heat is more evenly distributed than with the naked flame. The water-bath, usually of the form shown at a Fig. 51, is used where the temperature is to be kept below 100° (212 F.). It should alivays be used in evaporating liquids containing organic matter, and care should be had that it does not become dry. Fig. 51. In cases where it is desired to boil an aqueous liquid in a glass or porce- lain vessel; this is supported on a piece of wire gauze and a Bunsen burner or spirit lamp brought under it (Fig. 52). A piece of sheet-iron may be substituted for the wire gauze, with flat-bottomed vessels. The outside of the heated vessel must be dry. In heating liquids in test-tubes, the mouth of the tube must be held away from the person. It is best held by a piece of thick paper bent around the upper end of the tube (Fig. 53). The tube should be heated near, not at its bottom. In no case should flame, or the sand of the sand-bath, come in contact with a glass vessel above the level of the liquid within. Drying is always necessary as a preliminary to weighing, whether the Fig. 52. 364 MANUAL OF CHEMISTRY. substance is hygroscopic or not. It is usually effected in water ovens (Fig. 54), if a temperature of 100° (212' F.) be sufficient ; or in air ovens, somewhat similarly constructed, if a higher temperature be desired. As a substance can never be accurately weighed while it is warm, it is removed from the oven and placed in the desiccator (Fig. 55), over H S04 or CaCl2, until it has cooled. Fig. 54. Fig. 53. Iii cases where the substance would be injured by elevation of tem- perature, it is dried by allowing it to remain in the desiccator until it ceases to lose weight. Ignition has for its object the removal of organic matter by burning, and is conducted in platinum or porcelain crucibles. If a filter and pre- cipitate are to be ignited, they are first well dried ; as much as possible of the precipitate is detached and brought into the crucible, placed upon a Fig. 55. Fig. 56. sheet of white paper; the filter, with adherent precipitate, is then rolled into a thin cone, around which a piece of platinum wire is wound ; by means of the platinum wire the filter is held in the flame and burnt ; the remains of the filter are then added to the contents of the crucible, which is supported in the position shown in Fig. 56, in which it is heated, at first LABORATORY TECHNICS. 365 moderately, and the heat gradually increased to bright redness, at which it is maintained until no carbon remains. Before weighing, the crucible is to be cooled in the desiccator. In igniting it must not be forgotten that mineral substances may be modified or lost. Carbon at high temperature deoxidizes easily reducible substances; alkaline chlorides are partly volatilized; mineral bases com- bined with organic acids are converted into carbonates. In every instance only that amount of heat which is required is to be applied. In some cases it is well to accelerate the oxidation by the addition of ammonium nitrate. WEIGHING. The balance, Fig. 57, should always be kept in a glass case, containing a vessel with CaCl2, and in a situation protected from the fumes of the lab- oratory. The weights should be kept in a box by or in the balance case, which is to be closed when not in use. Fig 57. In weighing observe the following rules: (1.) See that the balance is in adjustment before using, especially if more than one person use it. (2.) Always put the substance to be weighed in the same pan, usually the left hand one, and the weights in the other. (3.) Never bring any chemical in contact with the pans, but have a pair of large watch-glasses of equal weight, one in either pan. Pieces of paper will not serve the purpose. (4.) Never add to or remove from either pan a weight of more than 0.5 gram without putting the balance out of action. (5.) Never weigh anything warm. (0.) In weighing a substance which has been dried do not consider the weight correct until two successive weigh' ings, with an intervening drying of a half hour, give identical results. (7.) MANUAL OF CHEMISTRY. In adding the weights, do so in regular order from above downward. (8.) In counting the weights, reckon the amount first by the empty holes in the box, and then tally in replacing the weights. (9.) Substances liable to ab- sorb moisture from the air are to be Aveiglied in closed vessels. Thus, Fig. 68. when a filter and its adherent precipitate are to be weighed together, they must be placed between the two watch-glasses (Fig. 58) as soon as taken from the drying-oven ; one of the watch-glasses being used to support the filter in the oven. MEASURING—VOLUMETRIC ANALYSIS. The principle upon which volumetric analysis is based is that by deter- mining the volume of a solution of known strength, required to accurately neutralize another solution of unknown strength, the amount of active sub- stance in the latter may be calculated. If, for example, we have a solution of silver nitrate which contains 170 grams to the litre, and we find that 12 c.c. of this solution precipitate all the chlorine from 10 c.c. of a solution of NaCl, it follows that the NaCl so- lution contains 70.20 grams of that substance per litre, because : NOsAg + NaCl = NO,Na + AgCl 170 58.5 85 143.5 and therefor each c.c. of the N03Ag solution will accurately precipitate 0.0585 grm. NaCl ; but as it has required 12 c.c. of tlieNOsAg solution to neutralize 10 c.c. of the NaCl solution, the latter contains 0.0585 x 12 = 0.702 p'm. NaCl or 1,000 contain 0.702 x 100 = 70.20 grins. NaCl. It is obvious, therefor, that the value of volumetric methods depends, among other things, greatly upon the accuracy of the standard solutions, as the solutions of known strength are called, and upon the accuracy of the measurements of volume. A standard solution containing in a litre of liquid a number of grams of the active substance, equal to its molecular weight, is a normal solution ; one containing that amount is a decinormal solution. An indicator is a substance which, by some char- acteristic reaction (end reaction), which will occur only when the substance to be determined has been completely removed, indicates the point when a proper volume of the standard solution has been added. The apparatus required for volumetric analysis consists of: (1.) A litre-flask (Fig. 59); a flask of such size that, when filled to the mark on the neck, at the temperature for which it has been graduated, it contains exactly 1,000 c.c. of water. Fig. 5.1. LABORATORY TECHNICS 367 (2.) A burette, which is a glass tube graduated into cubic centimetres, and having a stopcock or pinchcock at its lower extremity. (3.) A series of pipettes (Fig. 60), which are glass tubes, having bulbs blown upon them of such size that when they are tilled to a mark on the tube above the bulb, they contain a given number of cubic centimetres. (4.) Small beakers; stirring rods ; bottles for standard solutions. In making a standard solution the object to be attained is to have a solution, one litre of which shall contain a known quantity of the active material. If then in the formula for the nor- mal solution of silver nitrate : Fig. 60, Silver nitrate 170 grams. Distilled water 1,000 c.c. we weigh out the NO;,Ag on the one hand, and measure the H ,0 on the other, and mix the two, we will have, not what is desired, a solution containing 170 grms. N03Ag in 1,000 c.c. 11,0, but a solution of 170 grms. N03Ag in 1,000 -f x c.c. H O, in which x = the volume occupied by the N03Ag. Therefor, in making standard solutions, weigh out the active substances; introduce them into the litre- flask ; and then fill that to the mark with H.,0. Too much caution cannot be used in having pure chemicals and mak- ing accurate weighings in preparing volumetric solutions ; indeed the great disadvantage of the use of these methods by physicians is that the solutions which they use are care- lessly prepared and, consequently, the time which they spend in obtaining inaccurate, but seemingly accurate results is worse than thrown away. To use a volumetric solution it is poured into the bu- rette, whose stopcock has been closed, until above the o mark ; the stopcock is then slightly opened so as to expel all air from the delivery tube. The float (Fig. 61) is now introduced from above, and touched with a glass rod to free it from adhering air-bubbles; and the solution allowed to flow out from below until the mark on the float is opposite the o of the burette. All is now ready for use ; a given quantity of the solution to be analyzed is measured into a pipette and placed in a beaker, a few drops of the indi- cator solution are added, and the standard solution allowed to flow in un til the end reaction is reached. The reading of the burette is then taken and the calculation made. 1 IG. < 1. 368 MANUAL OF CHEMISTRY. SCHEME FOR DETERMINING THE COMPOSITION OF CALCULI. 1. Heat a portion on platinum foil: a. It is entirely volatile 2 b. A residue remains 5 2. Moisten a portion with HN03; evaporate to dryness at low heat; add NH4HO : a. A red color is produced 3 b. No red color is produced 4 3. Treat a portion with KHO, without heating: a. An ammoniacal odor is observed Ammonium urate. b. No ammoniacal odor Uric acid. 4. a. The HN03 solution becomes yellow when evaporated ; the yellow residue becomes reddish-yellow on addition of KHO, and, on heating with KHO, violet red.. Xanthin. b. The HN03 solution becomes dark brown on evapora- tion Cystin. 5. Moisten a portion with HN03; evaporate to dryness at low heat; add NH4HO : a. A red color is produced 6 b. No red color is produced 9 6. Heat before the blow-pipe on platinum foil: a. Fuses 7 b. Does not fuse 8 7. Bring into blue flame on platinum wire : a. Colors flame yellow Sodium urate. b. Colors flame violet Potassium urate. 8. The residue from 6 : a. Dissolves in dil. HC1 with effervescence ; the solution forms a white ppt. with ammonium oxalate.... Calcium urate. b. Dissolves with slight effervescence in dil. H,S04; the solu- tion, neutralized with NH4HO, gives a white ppt. with HNafJP04 Magnesium urate. 9. Heat before the blow-pipe on platinum foil: a. It fuses Ammonio-magnesian phosphate. b. It does not fuse 10 10. The residue from 9, when moistened with H20, is : a. Alkaline 11 b. Not alkaline Tricalcic phosphate. 11. The original substance dissolves in HC1: a. With effervescence Calcium carbonate. b. Without effervescence Calcium oxalate. Note.—A fresh portion of the powdered calculus is to be taken for each operation except where otherwise stated. ANALYTICAL SCHEME. 369 SCHEME FOR DETERMINING THE COMPOSITION OF AN IN- ORGANIC COMPOUND. SOLUBLE IN WATER OR IN ACIDS. Determination of Bases, 1. Acidulate with HC1: a. No ppt. is formed 5 b. A white ppt. is formed 2 2. Add HC1 drop by drop to complete precipitation, collect on filter, wash: a. Filtrate 5 b. Precipitate 3 3. Treat ppt. on filter with boiling H20, test filtrate with H4S : a. H ,S produces a black or brown color Lead. b. H,S does not cause darkening 4 4. Treat ppt. on filter with NH4HO : a. Ppt. turns gray or black Mercury(ous). b. Filtrate gives white ppt. with HN03 Silver. 5. Pass H.,S through clear, acid liquid : a. No ppt. is formed 18 b. A ppt. is formed 6 6. Treat with H,S, with occasional warming, to complete precipitation; collect ppt. on filter ; wash with H20 containing trace of H2S : a. Filtrate 18 b. Precipitate 7 7. Treat a portion of ppt. with NII4HS, warmed in test-tube : a. Ppt. is dissolved 8 b. A residue remains undissolved 13 8. Dry the remainder of ppt. from 6, mix it with equal parts of Na2C03 and NaNOs, and throw mixture in small portions into red-hot porcelain crucible ; when cold dissolve residue in HO ; filter: a. Filtrate 9 b. Residue 10 9. Add to the filtrate NH1H0,MgS04 and NH4C1, and rub inside of test-tube with glass rod : a. A white, crystalline ppt. forms immediately or after a time Arsenic. b. No ppt. forms Absence of As. 10. The residue is : a. White 11 b. Brown or black 12 11. Heat a portion of the residue in a platinum capsule with HC1, place a small piece of Zn in liquid : a. The platinum surface turns black Antimony. b. The HC1 liquid, removed by decantation, gives a white ppt. with excess of HgCl2 sol Tin. 370 MANUAL OF CHEMISTRY 12. The original solution : a. Gives a brown ppt. with FeS04 sol Gold. b. Does not give a brown ppt. with FeS04 sol., but gives a yellow ppt. with KC1 sol Platinum. 13. Wash undissolved residue and boil with dil. HNOa in porcelain capsule, filter: a. Filtrate .. 14 b. Residue (if any) , 17 14. Add dil. H..SO. to a portion of filtrate, warm, and let stand some time : a. A ppt. forms. Mix whole of filtrate with HoS04 dil., evap. over water-bath, extract residue with H.,0, filter, and treat filtrate according to 15 Lead. b. No ppt. forms 15 15. Add NHHO to remainder of filti'ate (or to filtrate from 14 a): a. A ppt. is formed. Filter and test filtrate according to 16 Bismuth. b. No ppt. is formed 16 16. Add SO, and CNSK to the liquid, evaporate, dissolve residue in H20, add H2S to solution : a. The solution 15 b. was blue Copper. b. The treatment 16 produced a yellow ppt Cadmium. 17. Is black, dissolves in aqua regia, and the solution gives a gray ppt. with SnCl2 Mercury(ic). 18. Boil portion of liquid to expel H S, add a few drops HN03, boil, add NH4HO just to alkaline reaction, add NHHS : a. Neither NH4HO nor NH4HS caused ppt 31 b. NH4HS caused ppt., N1I4H0 did not 20 c. NH4HO caused ppt 19 19. The original liquid is : a. Neutral 20 b. Alkaline or acid 28 20. Add to remainder of liquid 5 a. or 6 a. NH4C1, NH4HO just to alka- line reaction, and excess NH4HS, warm, filter, wash: a. Filtrate 31 b. Deposit 21 21. The deposit is : a. White 22 b. Colored '. 25 22. Dissolve deposit in small quantity HC1, boil, concentrate to small bulk, add NaHO, boil some time : a. A ppt. forms, which afterward dissolves 23 b. A ppt. forms, which does not redissolve 24 23. The solution 22 a. is divided into two parts : a. Treated with a small quantity of H,S gives a white ppt. Zinc. b. Treated with HC1 to acid reaction, and then with slight excess NHHO, gives, when heated, a white ppt. insol- uble in NH4C1 Aluminium. 24. Dilute, filter ; test filtrate for Zn and A1 as in 23. Dissolve ppt. in HC1, evaporate to small bulk, dilute, neutralize nearly with Na_CO:j, add BaCO.., filter, after standing : ANALYTICAL SCHEME. 371 a. Filtrate, treated with H2S04 and again filtered, gives solu- tion which, when made alkaline with NaHO, gives white ppt. with H2S Zinc. b. Residue (if any), heated with Na2C03 in outer blow-pipe flame, gives bead which is green when hot and bluish- green and opaque when cold Manganese. 25. The deposit is : a. Completely dissolved in dil. HC1 26 b. Not dissolved in dil. HC1 27 26. Boil to expel H,S, add HN03, boil, filter. Concentrate, add excess NaHO sol., boil, filter from residue b.: • a. Filtrate. Test for Zn and A1 as in 23. b. Divide residue into 3 parts : aa. Dissolved in HC1 dil. gives red color with CNSK.. Iron, bb. Fused with C03Na2 and KC103 forms yellow mass, which forms yellow sol. in H20 Chromium. cc. Treated as in 24 b. gives same results Manganese. 27. Filter, wash, examine filtrate according to 26. Heat portion of re- sidue with borax on platinum wire in blow-pipe flame : a. A transparent blue bead is obtained Cobalt. b. A bead is obtained, which is yellow when hot, nearly color- less when cold Nickel. 28. Add to remainder of liquid 5 a. or 6 a., NH4C1, NHHO just to alka line reaction, and NHtHS, warm, filter: a. A residue remains 29 b. No residue remains , 30 29. Treat filtrate as in 30. Examine residue for Ni and Co as in 27. 30. Boil to expel H2S, divide into 2 parts : a. Add dil. H2S04. If a ppt. form, filter, fuse ppt. with Na2C03, wash, dissolve in HC1, and test sol. for Ca, Ba, and Sr, according to 32. b. Heat with HN03, test small portion for Fe with CNSK, add Fe2Cl6, evaporate, add H„0,Na2C03 to near neu- tralization, and BaC03 ; stir, let stand until liquid is colorless. Separate ppt. aa. from filtrate bb.: aa. Boil ppt. with NaHO sol, filter; test filtrate for A1 by 23 b. and residue for Cr by 26 bb. bb. Mix filtrate with few drops HC1, boil, add NH,HO and NH4HS. If a ppt. form, test for Mn and Zn, as in 24. If no ppt. form, mix sol. with excess HoS04, boil, filter, add excess NH4HO and (NH4)2C204, filter, add HNa.,P04 to filtrate, a white ppt Magnesium. 31. Add to a small portion of the liquid NH4C1, (NH4).,C03 and NH4 HO, warm : a. A ppt. forms 32 b. No ppt. forms 36 32. Treat the whole of liquid with NH.C1, (NH4)2C03 and NH.HO as in 31, filter : a. Filtrate 36 b. Precipitate 33 372 MANUAL OF CHEMISTRY. 33. Wash, dissolve in small quantity dil. HC1, evaporate over water- bath, dissolve in a little H O, add CaS04 to a small portion of liquid : a. A ppt. fgrms 34 b. No ppt. forms 35 34. Add H„SiF6 to another portion of solution 33 : a. A ppt. is formed. A portion of the original solid colors the Bunsen flame green Barium. b. No ppt. formed. A portion of the original solid colors the Bunsen flame red Strontium. 35. Mix another portion of liquid 33 with (NH4)2C„04, a white ppt Calcium. 36. Add HNa2P04 sol. to a small portion of liquid, rub inner surface of test-tube with glass rod : a. A white, cystalline ppt Magnesium. b. No ppt 37 37. Evaporate, ignite, dissolve in small quantity H.,0, divide solution into two parts: a. Forms yellow, crystalline ppt. with PtCl4; colors flame vio- let (observe through blue glass) Potassium. b. Produces crystalline ppt. with potassium pyroantimonate; colors flame yellow Sodium. 38. Triturate original substance with CaH.,02 and H20 ; it develops an odor of ammonia Ammonium. Determination of Mineral Acids. After determination of abases, bear in mind what acids can possibly form soluble salts with the bases found (see Table L, p. 354), and limit the search to those. Examine separate portions of the original solution ac- cording to 1, 3, 4, 8, 10, 12, and 13. 1. Add HC1: a. Effervesces 2 b. A gelatinous ppt. is formed Silicate. 2. The gas given off in 1 a. has : a. No odor, and forms a white ppt. when passed through lime-water Carbonate. b. An odor of rotten eggs, and blackens paper moistened with Pb(C.,H302)3 Sulphide. 3. In testing for bases As was found; add sol. AgN03 and NH4HO : a. A yellow ppt Arsenite. b. A brick-red ppt Arsenate. 4. Add Ba(N03)2, and, if acid, add NH4HO to faint alkaline reaction: a. No ppt. formed 8 b. A ppt. is formed 5 5. Add HN03 to acid reaction to a portion of 4 b.: a. The ppt. does not redissolve completely ; filter; examine filtrate by b Sulphate. b. The ppt. redissolves 6 ANALYTICAL SCHEME. 373 6. Treat another portion of 4 b. or 5 a. with acetic acid : a. It dissolves completely Phosphate. b. It does not dissolve completely 7 7. Filter: a. Filtrate (in absence of As) gives white ppt. -with XH HO, NH,C1, and MgS04 Phosphate. b. Ppt. dissolves in dil. HC1; sol. gives ppt. with CaCl, in neutral solution Oxalate. 8. Acidulated with HN03; add sol. AgN03: a. A ppt. is formed 9 b. No ppt. is formed 10 9. Filter ; treat ppt. with HN03: a. It dissolves completely 10 b. It does not dissolve completely 12 10. The solid substance : a. Produces a yellow color with H,S04 Chlorate. b. Does not produce a yellow color with H.,S04 11 11. Divide liquid 9 a. into 4 parts : a. Gives white ppt. with NH4HO, NH4C1, and Mg S04 Phosphate. b. Acidulated slightly with HC1, turns turmeric paper red Borate. c. Acidulate with HC1, evaporate to dryness, add HC1, an insoluble residue remains Silicate. d. A portion of original substance, moistened with H.,S04, gives off gas which corrodes glass Fluoride. 12. The original liquid gives : a. A blue color with a drop of chlorine water and starch paste Iodide. b. A blue ppt. with sol. FeS04 + Fe2(SO,)3 Cyanide. c. Is colored yellow or brown by chlorine water, but does not react as in 12 a Bromide. d. Ppt. 8 a. is readily soluble in NH4HO Chloride. 13. Heat the dry salt with Cu and H.,S04 and conduct the gas through sol. Fe2(S04)3, which it turns brown Nitrate. 374 MANUAL OF CHEMISTRY. TABLE I.—SOLUBILITIES. Frezenius. W or w = soluble in H20. A or a = insoluble in H20 ; soluble in HC1, N03H, or aqua regia. I or i = insoluble in H20 and acids. W-A = sparingly soluble in H20, but soluble in acids. W-I = sparingly soluble in H20 and acids. A-I = insoluble in H20, sparingly soluble in acids. Capitals indicate common substances. 5 11 =9 g • § a a t > =■ 2' 't.r =• = x ■Stag. „ 5 II O gn L?2^ Borate .... Bromide... Carbonate . Chlorate... Chloride... Chromate . Citrate .... Cyanide ... Femcyanide Ferrocyanid Fluoride ... Formate ... Hydrate ... Iodide Mai ate Nitrate .... Oxaiate. . .. Oxide Phosphate . Silicate.... Succinate.. Sulphate... Sulphide.. . Tartrate. .. Acetate Arsenate... Arsenite Benzoate . rsQlli !> 8— a >■ g-S 11 %9 a> ST'fifi nig? ■c a t> >• : P SS SH : 3: 3 3 p p : p^ Aluminium. “JPiSii 'o SB 3 2J ' ts ~ 2. p 3 “?3 2 | C II 00 -Irp,^ o2 c- ? =>> S'S.a'I' is*8 -iiT'1 ~; „s« sg&sg„„ II .2 = *•£'§ p >“S 5.2? Ammonium. %>£*: : f *»::?►:*: : ’ ’ S3 • • • 85 J • • 1 • : p p *. Antimony. 85 9 l * 3s-1.1: P P P M p f p p p p p P Barium. : : s : : » » >-» P o : : p 3 Bismuth. 7 f : : p p ppp^^p^T P Cadmium. (►i-tp |>t> p (> pp^ p p p Calcium. - B a"!. || * g*\9g;5? Uispiu sI' S^ 3 I ►: : — H? p^pf^pfp M *-*• : : p 3 Chromium. 3 > 3 ? — *- M P P : p p 3 Cobalt. 3; r3 SM p, s* s 0 o - m * Q£ = “ 0-3 §tSsL« 3l:,-3-o JirZ’ 11 ’ L.loll ?. %oSf m3.— i S-— # 1—1 {> P * ?mp-: P p^ji^^t>^p P >P z* Copper. iP^^^PPPP^* P P Ferrous. p p |>p 3 : p P P 3< Ferric. p;>^ppp>.p^ffpfppf M P [». P P pp^^>>ltD p p p Lead. || g 9 0% ? - -«li|! 3*?Sg? P P p P 3 Magnesium. f ?^S^PP- p o» P pp^^^t=*^p P P Manganese. ** _l -fl — ii w f« o 3 a <; i p i'p: : P P £> M : f: P P P *f P Mercurous. S3-’"II l.2 31'33 f: : ® -j P p p f f p * : P P o» s: i p p p Mercuric. 53 ■“ KlP =i <1 p « m ? — p. Nickel. QS" -wo » a J. = 9 <3^W — • >o3‘^ - Ji§5 Potassium. P . iJ p »7s: p p p m.; — — -1> p • P P 3 P Silver. P- oS-wu - Esr’ > Sodium. - v = «• I §.§2* »?H| l,C • p P 1 3 >3 » P : p p 3 Strontium. a s"^» O ° a'P P p p gjs: : ppp: : : : p : p : ?m Stannous. a 3 2.5“ - aL.g^ 8 os 53 ; -s§T5 1 s»^i 1 3 s s55 s- l*ST ■3 2 OOJ - S| 2o » aMSr f II 3 .►§* t> t> : g: p : p p : . . : : : : : : Stannic. w P P p|^^^t>^p : : : * Zinc. Femcyanide. Ferrocyanide. Fluoride. Formate. Hydrate. Iodide. Malate. Nitrate. Oxalate. Oxide. Phosphate. Silicate. Succinate. Sulphate. . Sulphide, j Tartrate. Borate. Bromide. Carbonate. Chlorate. Chloride. Chromate. Citrate. Cyanide. »>>■!> § 3 S 3 § 3 3 S' In-* WEIGHTS AND MEASURES. TABLE H—WEIGHTS AND MEASURES. Measures of Length. 1 millimetre = 0.001 metre = 0.0394 inch. 1 centimetre = 0.01 “ = 0.3937 “ 1 decimetre =0.1 “ = 3.9371 inches. 1 METRE = 39.3708 “ 1 decametre = 10 metres = 32.8089 feet. 1 hectometre = 100 “ = 328.089 “ 1 kilometre = 1000 “ = 0.6214 mile. Inch. Millimetres. Inches. Centimetres. Inches. Centimetres. y. 4 — 0.3819 2 _ 5.08 » = 22.86 Vsa = 0.7638 3 = 7.02 10 — 25.40 Vi, = 1.5875 4 — 10.16 11 — 27.94 Vs = 3.175 5 = 12.70 12 = 30.48 V* = 0.35 6 — 15.24 18 = 45.72 v. = 12.7 7 = 17.78 24 — 60.96 1 = 25.4 8 = 20.32 36 = 91.44 Measures of Capacity. 1 millilitre = 1 c.c. = 0.001 litre = 0.0021 U. S. pint. 1 centilitre = 10 “ = 0.01 “ = 0.0211 “ “ 1 decilitre = 100 “ = 0.1 “ = 0.2113 “ “ 1 LITRE = 1000 = 1.0567 “ quart 1 decalitre = 10 litres = 2.6418 “ galls. 1 hectolitre — 100 “ = 26.418 “ “ 1 kilolitre = 1000 “ = 264.18 “ “ 2 I1 II II II II II II II II II II II II II II II II II II II h-1. H-* l-i. O .-rGGGGGG^GGGGGOG o p c^co^^^-u^^^occoo-i^w^iowH fi II II II II II II II II II II II II II II II II II II II II iOJOJOJOJOJOJOiO-4'-4)-4)-1)-4*-4)-4)-4)-4)-^-4)-4 o oso^cowasc^ai^ot^ccjio^a'Moso p O^GO-}C5QlJ-.CO-*GeOiJO GOrJOCC^^-^CO m j: j: r. *} -i oo x c » • • • • f _ •. • p OS vx G 05 00 JO os »-»■ cr -^Scofeocoo n ON II II II II II II II II II II II II II II II II II II »£k. k£t £» CO CO CO i_j —) 0— <—l 00 Or ifO £7. co >_o co »u at p os 22 r* co Qp co a> iu g57 ►-‘■mG^bojo •s!OCOC5 ft) H^-JCfOW MANUAL OF CHEMISTRY. Weights. 1 milligram = 0.001 gram = 0.015 grain Troy. 1 centigram = 0.01 “ = 0.154 “ 1 decigram =0.1 “ = 1.543 “ 1 GRAM = 15.432 grains " 1 decagram = 10 grams = 154.324 “ 1 hectogram = 100 “ = 0.268 lb. 1 kilogram = 1000 “ = 2.679 lbs. “ Grains » So S ii ii ii ii ii ii ii ii ii ii ii ii ii ii ii ii ii ii ii ii ii ii ii ii n ii l-M_M-M_M_i©ooOOOOOOOOOOOOOOOOOO o >£>'-‘►-‘.0000000 COWOOCO^C^^M^aMUKXWOtXCC^WMOCOC C5H-‘OiN5-3^Ji$aD^o!ucO»fc».Orf*.o£SoOTOOOHi 3 , , OOT©TCtOtO»CNCTC7»OtC?T£k.hU.>{^ GD«sf w C*>CCD^C:Wi^«ieMOcD00-l © p S' II II II II II II II II II II II II II II II II II II II II II II cocccocococococococococococo o >—1 >0 CO Qt O -7 GO 00 00 ~7 O O OT *£*■ CO CO O aWU»CW-05*JCO«lC^-7M^ aMCO^^^^tUOWOCJtOOJ 3 i 9 I-M-IV-; . co WmOOCO»305W^MWm C*N II II II II II II II II II II 11 11 11 11 11 11 11 11 11 11 11 11 C0C0C0fcD>£>O>— CC