ANTHONY . .N3ROC.: .. . UNIVERSITY OF CALIFORNIA MEDICAL CENTER LIBRARY SAN FRANCISCO Gift of J.J. McGinnis, M.D. TEXT-BOOK OF CHEMISTEY INORGANIC AND ORGANIC WITH TOXICOLOGY FOR STUDENTS OF MEDICINE, PHARMACY, DENTISTRY AND BIOLOGY BY R. A. WITTHAUS, A.M., M.D. LATE PROFESSOR OF CHEMISTRY, PHYSICS AND TOXICOLOGY IN CORNELL UNIVERSITY , i&ebteeb Cbttion BY R. J. E. SCOTT, M.A., B.C.L., M.D. FELLOW OF THE NEW YORK ACADEMY OF MEDICINE: EDITOR OF " WITTHAUS' ESSENTIALS OF CHEMISTRY AND TOXICOLOGY," ETC., ETC. NEW YORK WILLIAM WOOD AND COMPANY MDCCCCXIX COPYRIGHT, 1919 BY WILLIAM WOOD AND COMPANY w PREFACE In the preface to the earlier editions of this book the author clearly specified its scope and purpose. The general plan of the work remains unaltered, and may be indicated by the following extracts from the preface to the sixth edition. ' The main purpose of the section on inorganic chemistry is to supply certain data which shall serve as the text upon which to discuss the general principles of chemistry. It is the opinion of the author that the object of chemical teaching should not be to lay up in the memory of the student a store of isolated facts, but rather to train his mind in those general principles by which he may reason out chemical problems for himself. If a teacher of chemistry to medical students aim merely to supply them with chemical facts, he and they are fore- ordained to disappointment, but if the student be led to ' think in chemistry,' the success and possible extent of the teaching, both in the fundamentals and in the superstructure of organic and physio- logical chemistry, which can be attained, will be surprising and delightful to both instructor and pupil. And in this connection it must be said that the order of consideration of the several subjects which has been here followed, because it is logical, is not recommended in the teaching of students. The study should begin with that of a few elements and compounds, the consideration of the general physical and chemical principles being taken up as material for their discussion is supplied. 1 ' The section on organic chemistry has been rearranged in the light of further information upon the relationship of substances, and somewhat extended, the prominence given to this branch of the subject the author believes to be justified, notwithstanding its intricacy and the impossibility of teaching it satisfactorily to those not well grounded in general chemistry, because of the intimate connection of organic chemistry with physiology and with modern pharmacy, and the impossibility of the comprehension of the problems of animal and pharmaceutical chemistry without the possession of an adequate knowledge of the principles of organic chemistry/' Since the first edition of this book appeared, and particularly since the death of its distinguished author, many changes have occurred in the medical curriculum; and not the least of these pertain to the iii 92790 IV PREFACE subject of chemistry. Inorganic chemistry and the principles of organic chemistry are now generally presumed to have been mastered in the preparatory schools, and their study is reviewed and amplified in the first year of the medical course as preliminary to the important (special) subject of physiological chemistry. The book is still intended mainly for medical students, and the present revision has been made with the purpose of providing a work which shall be suitable for students in the preparatory and scientific schools, and which may also serve as a text-book for the medical or professional student throughout his college course. During the process of revision the main difficulty has been to pre- vent the book from becoming of unreasonable size. Many of the sections on Physics have been omitted, it being presumed that the student possesses, and has studied, a text-book on that subject. The part dealing with Physiological Chemistry is omitted, because the subject is now of such importance and of such dimensions that its study is more advantageously made from special text-books, of which there are now many excellent ones available. Such of the organic chemistry as could be spared has also been left out, and further space has been gained by printing in smaller type the sections on toxicology and some of the less important general topics. The equations have been printed each on a line by itself, so as to make the subject clearer and more attractive to the beginner. Care has been taken not to make the book (particularly the part dealing with Organic chemistry) a mere catalogue of names and formulae. New material has been added where it was considered necessary, and care has been taken to present and emphasize general principles rather than isolated facts. In several of the sections of the organic chemistry equations showing the Grignard reactions have been freely introduced. Many of the new paragraphs were indicated by the late Professor Witthaus as desirable, and, in some cases they have been taken from his manuscript notes. R. J. E. SCOTT. New York. September, 1918. TABLE OF CONTENTS INTRODUCTORY GENERAL CHEMISTRY PAGE Matter Force Chemistry .......................... 1 General Properties of Matter: Indestructibility Impenetrability Divisibility Inertia Weight Apparent Weight Energy Specific Weight Density Pressures States of Matter Cohesion ....................................... 2 Special Properties of Solids, Liquids and Gases ............. 4 Crystallization Allotropy Diffusion Boyle-Mariotte Law Absorption of Gases ....................... 4 Some Physical Actions of Chemical Interest ............... 11 HEAT: Temperature Thermometers Thermal Unit Changes in Volume Dalton-GayLussac Law Law of Charles Absolute Temperature Change of State Fusion Latent Heat Solution - Congelation Vaporization Gases and Vapors Boiling Liquefaction Distillation Subli- mation Specific Heat ...................... 11 ELECTRICITY : Insulators Conductors Ions Galvanic Electricity Electromotive Force Resistance Ohm's Law Electrolysis Electrical Units ........... ... 17 Chemical Phenomena .................................... 21 Elements Compounds Mixtures Laws Governing the Combination of Elements Molecular and Atomic Theories Atomic Weight Molecular Weight Mol Molecular Volume Valence Symbols, Formulae and Equations Electrolysis Acids, Bases and Salts Concentration Stoichiometry Nomenclature Radicals Composition and Constitution Chemical Energy Chemical Equilibrium Reversible Re- actions Mass Action Chemical Effects of Light Classification of Elements Periodic Law .......... 21 VI TABLE OF CONTENTS INORGANIC CHEMISTRY PAGE Typical Elements 57 Hydrogen 57 Oxygen Ozone 59 Compounds of Hydrogen and Oxygen: Water Natural Waters Hydrogen Dioxide 62 Elements which form no Compounds 72 Helium Neon Argon Krypton Xenon Niton 72 Acidulous Elements 73 CHLORINE GROUP 73 Fluorine and its Compounds 73 Chlorine and its Compounds 74 Bromine and its Compounds 80 Iodine and its Compounds 81 SULPHUR GROUP 83 Sulphur and its Compounds 84 Selenium and Tellurium 93 NITROGEN GROUP 93 Nitrogen and its Compounds Atmospheric Air .... 94 Phosphorus and its Compounds 103 Arsenic and its Compounds 110 Antimony and its Compounds 120 BORON GROUP 123 Boron and its Compounds 123 CARBON GROUP 124 Carbon 124 Silicon and its Compounds 127 VANADIUM GROUP 128 Vanadium Columbium Tantalum 128 MOLYBDENUM GROUP 128 Molybdenum Tungsten Osmium 128 Amphoteric Elements 129 GOLD GROUP 129 Gold and its Compounds 129 IRON GROUP 130 Chromium and its Compounds 130 Manganese and its Compounds 131 Iron and its Compounds 132 TABLE OF CONTENTS Vll PAGE URANIUM GROUP 137 Uranium and its Compounds 137 LEAD GROUP 138 Lead and its Compounds 138 BISMUTH GROUP 142 Bismuth and its Compounds 142 TIN GROUP 144 Titanium 145 Zirconium 145 Tin and its Compounds 145 PLATINUM GROUP 147 Palladium Platinum and its Compounds 147 RHODIUM GROUP 147 Rhodium Ruthenium Iridium 147 Basylous Elements 149 SODIUM GROUP 149 Lithium and its Compounds 149 Sodium and its Compounds 151 Potassium and its Compounds 156 Caesium Rubidium 163 Silver and its Compounds 164 Ammonium Compounds 165 THALLIUM GROUP 168 Thallium 168 CALCIUM GROUP 168 Calcium and its Compounds 168 Strontium and its Compounds 171 Barium and its Compounds 171 MAGNESIUM GROUP 172 Magnesium and its Compounds 173 Zinc and its Compounds 175 Cadmium 177 ALUMINIUM GROUP 177 Glucinum Scandium Gallium Indium 177 Aluminium and its Compounds 178 NICKEL GROUP t 180 Nickel and its Compounds 180 Cobalt 181 COPPER GROUP 181 Copper and its Compounds 181 Mercury and its Compounds 184 Vlll TABLE OF CONTENTS ORGANIC CHEMISTRY PAGE Compounds of Carbon: Organic Chemistry Homologous Series Isomerism Elementary Organic Analysis Determination of Mo- lecular Weights Determination of Constitution Characterizing Groups Nomenclature Classifica- tion of Carbon Compounds 191 Open Chain, Aliphatic, Acyclic, or Fatty Compounds 201 Hydrocarbons 201 Saturated Compounds Methane Series 201 Hydrocarbons 202 Haloid Derivatives 204 .Oxidation Products 208 Alcohols 210 Aldehydes and Ketones 225 Carbohydrates 235 Carboxylic Acids 250 Alcohol-acids Oxyacids 259 Aldehyde-acids 265 Ketone-acids 266 Oxyaldehyde and Oxyketone Acids 266 Simple ethers 267 Acid Anhydrides 269 Acidyl Halides 270 Oxides of Carbon 270 Esters Compound Ethers 275 Sulphur Derivatives of the Paraffins 284 Organo-metallic Compounds 288 Nitrogen Derivatives of the Paraffins 291 Nitroparaffins 292 Amines and Ammonium Derivatives 292 Oxyamines Hydramines Diamines 296 Amidines Amid ximes Hydroxamic Acids .. . 300 Guanidine and its Derivatives 301 Hydrazines Hydrazides 302 Nitriles Cyanogen Compounds 303 Amides 310 Thiourea and Thiocarbamic Acids 316 Compound Ureas 316 TABLE OF CONTENTS ix PAGE Nitrogen Derivatives of Alcohols, Aldehydes and Ketones 319 Nitrogen Derivatives of Acids 321 Phosphorus, Antimony and Arsenic Derivatives 326 Unsaturated Aliphatic Compounds 327 Hydrocarbons 327 Oxidation Products 330 Sulphur and Nitrogen Compounds 333 Closed Chain, Aromatic, or Cyclic Compounds 334 Carbocyclic Compounds 335 Hexacarbocyclic Compounds Aromatic Substances 336 Monobenzenic Compounds 341 Hydrocarbons 341 Haloid Derivatives 343 Phenols 344 Quinones 350 Aromatic alcohols 351 Alphenols 352 Aldehydes 353 Ketones 354 Aromatic Carboxylic Acids 355 Phenol Carboxylic Acids and their Esters 357 Phenylic Ethers Glucosides 360 Anhydrides and Acid Halides 364 Aromatic Sulphur Derivatives Sulphonic Acids 365 Nitrogen-containing Derivatives of Benzene 367 Hydroaromatic Compounds with a Single Nucleus. . 381 Hydrocarbons 381 Hydroaromatic alcohols 382 Hydroaromatic Ketones and Acids 383 Compounds with Condensed Nuclei 385 Condensed Hydrocarbons 386 Phenols Quinones 386 Diphenyl and its Derivatives 388 Diphenyl Paraffins Diphenyl Olefines Diphenyl Acetylenes 388 Phenols Alcohols 389 Heterocyclic Compounds 389 Mononucleate Heterocyclic Compounds 391 Five-membered rings 391 Six-membered rings 396 X TABLE OF CONTENTS PAGE Condensed Heterocyclic Compounds 414 Condensed Nuclei Containing a Nitrogen Member 415 Alkaloids 419 Ptomaines, Leucomain^s and Toxines 442 APPENDIX 445 INDEX . 449 TABLE OF WEIGHTS AND MEASURES WEIGHTS milligram = 0.001 gram = 0.015 grain Troy. 0.154 " 1.513 grains " 15.432 " 1 centigram = 0.01 1 decigram = 0.1 i GRAM 1 decagram = 10 grams =154.324 " " 1 hectogram = 100 " 0.268 pound " 1 kilogram =1000 " = 2.679 pounds " 1 grain = 0.065 gram. 1 dram = 3.888 grams. 1 ounce = 31.103 " 1 pound = 373.25 1 pound Avoirdupois = 453.5925 grams. 1 kilo = 2.2046 pounds Avoirdupois. MEASURES OF LENGTH 1 millimeter =0.301 meter = 1 centimeter = 0.01 1 decimeter =01 i METER 1 decameter 1 hectometer = 100 1 kilometer = 1000 0.0394 inch. 0.3937 ll 3.9371 inches. = 39.3708 " = 10 meters = 32.8089 feet. = 328.089 " = 0.6214 mile. 1 inch = 2.54 centimeters. 1 foot = 30.48 centimeters. MEASURES OF CAPACITY 1 milliliter 1 centiliter 1 deciliter i LITER 1 decaliter 1 hectoliter 1 kiloliter = 1 = 10 = 100 = 1000 c.c. = 0.001 liter " =0.01 " = 0.1 = 10 liters = 100 " = 1000 " 0.0021 U. S. pint. 0.0211 " 0.2113 " 1.0567 " quart. 2.6418 " gallons. 26.418 " = 264.18 MEASURES OF VOLUME cubic meter = 1000 liters. cubic centimeter = liter = liter = 1 minim = 1 fluid dram 1 cubic centimeter = 1 fluid ounce 0.001 liter. 1 cubic decimeter. 1.0567 quarts. 0.0614 cubic centimeter. 3.70 cubic centimeters. 0.061 cubic inch. 29.57 cubic centimeters. 47.ll cubic centimeters, xi SIGNS AND ABBREVIATIONS The figures in parentheses indicate the page upon which the meaning of the sign or abbreviation is described. [a] ^Specific rotary power for so- dium light. = Water of crystallization (64). ^Atmospheric pressure. ^Boiling point (16). = Asymmetric carbon atom ( 239 ) . = Asymmetric carbon atom (239 ) . =Gram calorie (12). =Cubic centimeter. Cubic centimeter. Centimeter. ^Chemically pure. =Dextrogyrous (239). ^dilute. =Racemic (239). =Decimeter. = Electromotive force (20). EMF ^Electromotive force (20). Eq-N ^Equivalent normal solution (38). f.p. ^Fusing point (14). gm ^:Gram. i =Racemic (239). i =Iso. insol. ^Insoluble. K ^Rational calorie (12). kg ^Kilogram. kg:cal=Large calorie (12). L =Liter. i =Laevogyrous (239). aq atm b.p. C C* cal. cc c.c. cm C.P. d dil. d+1 dm E m m mm M-N M.w. N N/10 n = o = p ppt. pts. R R r sp. gr. SS T t U.S.P. Vm Vs A Meter. Meta. Millimeter. Molecular normal solution ( 37 ) Molecular weight. Normal (38). Tenth normal (38). Index of refraction for so- dium light. :Para. Precipitate. Parts. A cyclic compound. Resistance. Racemic (239). Specific gravity. Standard solution (38). Absolute temperature (13). Temperature in degrees Centi- grade. United States Pharmacopoeia. Molecular volume (29). :Specific volume (4). Double linkage. Wave length of light. Micromillimeter=.001 milli- meter. Dextrogyrous. Laevogyrous. xii TEXT-BOOK OF CHEMISTRY INTRODUCTORY GENERAL CHEMISTRY. Matter and Force. As we only become cognizant of matter by the action of force upon it, or of force through its effects upon mat- ter, our appreciations of each are so interwoven that each is usually defined in terms of the other. This "argument in a circle" may be avoided by saying that matter is that which occupies space. In popular language the' words matter and substance are used synonymously; but in chemical language the latter word has a more narrow meaning. A substance is a species of matter, having con- stant characters and properties by which it may be recognized, and differentiated from other substance species, irrespective of its shape. Thus sulphur, water, chalk are chemical substances, each of which, in any form in which it may appear, has definite qualities by which it may be distinguished from all other species of substance. Force is that which produces, or tends to produce motion, or change of motion of matter. Chemistry. The simplest definition of chemistry is a modifica- tion of that given by Webster : That branch of science which treats of the composition of substances, their changes in composition, and the laws governing such changes. A bar of soft iron may be made to emit light when heated, or sound when caused to vibrate, or magnetism when under the influ- ence of an electric current. Under the influence of these physical forces the iron suffers no change in composition, and, on cessation of the action of the inciting force the iron returns to its original condition. But if the iron is heated in an atmosphere of oxygen, both the iron and a part of the oxygen disappear, and a new sub- stance, a new chemical species, is produced, having properties of its own, different from those of either the iron or the oxygen. In this case there has been chemical action, causing change of composition, as the new substance contains both iron and oxygen. The result of such action is, moreover, permanent, and the new product continues to exist, until modified by some new manifestation of chemical action. While chemical action is thus different in its results from the action of physical forces, there exists the most intimate relation between them. The line of demarcation between chemical actions and certain physical actions, such as solution, although distinct, is narrow. Many chemical actions take place only under certain physi- 1 2 TEXT-BOOK OF CHEMISTRY cal conditions, such as of temperature; or are provoked by physical forces, such as light. It is assumed that the student has already acquired a grounding in physics, and that he is in possession of, and uses, a standard text- book on that subject. GENERAL PROPERTIES OF MATTER. Indestructibility. The result of chemical action is change in the composition of the substance acted upon, a change accompanied by corresponding 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 atmos- phere 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. Impenetrability. Although one mass of matter may penetrate another, as when a nail is driven into wood, or when salt is dissolved in water, the ultimate particles of which matter is composed cannot penetrate each other, and, in cases like those above cited, the particles of the softer substance are forced aside, or the particles of one substance occupy spaces between the particles of the other. Such spaces exist between the ultimate particles of even the densest sub- stances. Divisibility. All substances are capable of being separated by mechanical means into minute particles. Although we have no direct experimental evidence of a limit to this divisibility, we are warranted in believing that matter is not infinitely divisible. A strong argu- ment in favor of this view is that, after physical subdivision has reached the limit of its power with compound substances, these may be further subdivided into smaller, dissimilar quantities by chemical means. The limit of physical subdivision of matter is the molecule of the physicist, the smallest quantity of matter with which he has to deal, the smallest quantity that is capable of free existence (pp.24, 25). Inertia is that negative quality of matter by virtue of which it cannot of itself produce any change in the condition of rest or of motion in which it may be. If matter be at rest it can only be put in motion by the expenditure of work upon it, and, if it be in motion, such motion will continue, rectilinear, uniform, and indefinite, unless interfered with by the interposition of other energy. 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 GENERAL PROPERTIES OF MATTER 3 earth, becomes sensible as weight, when the motion of the attracted body toward the center 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 determined 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 counter-poising 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 displaced. For this reason the appar- ent 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. Energy is the capacity of matter for doing work. Energy in- cludes both that exertion which is doing work, which is known as actual or kinetic energy, and that capacity to do work which is known as possible or potential energy. The relative amounts of the two forms change constantly, but their sum is a constant quantity; i^e., energy, like matter, can neither be created nor destroyed. ^The Specific Weight, or Specific Gravity, or Relative Density of a substance is the weight of a given volume of the substance as com- pared with the weight of an equal volume 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, and are usually determined at 15 C. ; those of gases to air or to hydrogen. In expressing the sp. gr. of heavy liquids, the weight of one cc. of water is taken as the unit. Thus the sp. gr. of sulphuric acid being 1.84, 1 cc. of water weighing 1 gm., 1 cc. of sulphuric acid weighs 1.84 gms. For light liquids one liter of water is the unit. Thus 1 liter of a liquid of sp. gr. 1026 weighs 1026 gms., or 1.026 kg. In metric, therefore, the weight of 1 cc., or of 1 liter of a liquid represents its specific gravity. The absolute density of a body is the ratio between its volume and its weight, and is obtained by the formula D=^, in which D is the density, P the weight, and V the volume. Clearly, also P=VD, and V=^. When V is taken as the unit of volume the equation D= be- comes D=P; i. e. y the absolute density of a substance is the weight of 4 TEXT-BOOK OF CHEMISTRY unit volume of that substance. But as the weight of a given volume of a substance, particularly in the liquid or aeriform state, varies with differences of temperature and of pressure, a definite tempera- ture and pressure have been arbitrarily selected as constituting normal conditions. The temperature is 0C., and the pressure that of a column of mercury 76 centimeters high at 45 latitude. Pressures are measured either by the height of a column of mer- cury which the pressure will sustain in opposition to gravity, in cm. or mm. ; or in atmospheres, one atm. being the pressure which will sustain a column of mercury of the average height of the barometer ; i. e., 760 mm. As the specific gravity (below) of mercury is 13.6 at 0C., 1 cc. of mercury weighs 13.6 gms., and each mm. of mercurial column is equivalent to a pressure of 1.36. per sq. cm., and one atm. of pressure is equal to 1033.6 gms. per sq. cm. The specific volume of a substance (Vs) is the reciprocal of its absolute density: Vs=0, and is the volume, in cc., which one gram occupies under normal conditions. Thus for hydrogen: . jnr J T j r =lllll cc., or 11.11 L., for oxygen: .-mnVs? =699.7 cc., and for air: .inn 1 =773.4 cc. States of Matter. Matter exists in the' three forms of solid, liquid and gas (or vapor). The term fluid applies to both liquids and gases; the former being distinguished as incompressible, the latter as compressible fluids. Cohesion is the force by which molecules of the same kind are held together. It is most active in solids, which therefore have definite shape and magnitude. In liquids it is much less active, yet sufficient to maintain a definite magnitude of the liquid, but it is in part overcome by gravity, which causes the liquid to assume the shape of the containing vessel. In gases cohesion is almost nil ; therefore, the shape and volume of any gas are those of the containing vessel. Cohesion diminishes with the addition of heat; therefore, by adding heat to a solid it is, if not decomposed, converted into a liquid and then into a gas. SPECIAL PROPERTIES OF SOLIDS, LIQUIDS AND GASES. Crystallization. Solid substances exist in two forms, amor- phous and crystalline. Amorphous substances assume no geometric shape; they conduct heat equally well in all directions; they break irregularly; and, if transparent, allow light to pass through them equally well in all directions. A solid in the crystalline form has a definite geometrical shape; conducts heat more readily in some directions than in others; when broken, separates in certain direc- tions, called planes 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. CRYSTALLIZATION 5 Crystals are formed in one of four ways: 1. An amorphous sub- stance, 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 sublimed 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 sub- stance. If the evaporation be slow and the solution at rest, the FIG. 1. 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 symmetrical halves. Such planes are called planes of symmetry. Thus in the crystals in Fig. 1 the planes ab ab, ac ac, and be be are planes of symmetry. When a plane of symmetry contains two or more equivalent linear J FIG. 2. directions passing through the center, it is called the principal plane of symmetry; as in Fig. 2 the plane ab ab, containing the equal linear directions aa and bb. Any normal erected upon a plane of symmetry, and prolonged in both directions until it meets opposite parts of the exterior of the 6 TEXT-BOOK OF CHEMISTRY 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 2, aa, bb, and cc are axes of symmetry, and cc is the principal axis. Upon the relations of these imaginary planes and axes a classifica- tion 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. 1, crossing each other at right angles. The simple forms are the cube; and its de- rivatives, 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, Tetrag- onal, or Dimetric System contains those crystals having three axes placed at right angles to each other two as aa and bb, Fig. 2, 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 , IA FIG. 3. octahedron. The crystals of this system expand equally only in two directions when heated. They refract light doubly in all directions, except through one axis of single refraction. III. The Rhombohedral or Hexagonal System includes crystals having four axes, three of which aa, aa, aa, Fig. 3, 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 rhombohedron, and the scalenohedron. CRYSTALLIZATION 7 These crystals expand equally in two directions when heated, and refract light singly through the principal axis, but in other directions refract it doubly. IV. 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. 2 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 rectangular octahedron, and the right rec- tangular 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. 4, are at right angles ; the third, bb, is perpendicular to one and FIG. 4. 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, cross- ing each other at angles not right angles ; Fig. 4, 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, expand 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 artificially have some one of the forms mentioned above, or some modification 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. 5 are produced. It sometimes happens in the formation of a derivative form that alternate faces are excessively developed, producing at length entire 8 TEXT-BOOK OF CHEMISTRY obliteration of the others, as shown in Fig. 6. Such crystals are said to be hemihedral. They can be developed only in a system having a principal axis. Isomorphism. In many instances two or more substances crystal- lize in forms identical with each other, and, in most cases, such substances resemble each other in their chemical constitution. They are said to be isomorphous. This identity of crystalline form does not depend so much upon the nature of the elements themselves, as FIG. 5. FIG. 6. 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 without 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 iden- tical 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 octa- hedra; when obtained by cooling melted sulphur the crystals are oblique prisms. Occasional instances of trimorphism, of the forma- tion of crystals belonging to three different systems by the same sub- stance, are also known. Many substances on assuming the crystalline form, combine with a certain amount of water which exists in the crystal in a solid combination. Thus nearly half of the weight of crystallized alum is water. This water is called water of crystallization, and is neces- sary to the maintenance of the crystalline form, and frequently to the color. If blue vitriol is heated, it loses its water of crystalliza- DIFFUSION OF LIQUIDS 9 tion, and is converted into an amorphous, white powder. Some crystals lose their water of crystallization on mere exposure to the air. They are then said to effloresce. Usually, however, they only lose their water of crystallization when heated (p. 64). Allotropy. Dimorphism apart, a few substances are known to exist in more than one solid form. These varieties of the same substance exhibit different physical properties, while their chemical qualities are the same in kind, but differ in their degrees of activity. 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 and amorphous. Carbon exists in three allotropic forms : two crystalline, the diamond and graphite ; the third amorphous. For other examples of allotropy, see ozone, phosphorus, and silicon. In passing from one allotropic modification to another, a sub- stance absorbs or gives out heat. Diffusion of Liquids Dialysis. If a liquid is carefully floated upon the surface of a heavier liquid, with which it is capable of mix- ing, two distinct layers are at first formed. But, even at perfect rest, mixing of the two liquids, in opposition to gravity, will begin immediately, and progress slowly until the two liquids have diffused into each other to form a single liquid whose composition and density are the same throughout. If, in place of bringing the two liquids into direct contact, they are separated from each other by a membrane of goldbeater's skin, each will pass through the membrane into the other, a phenomenon called osmosis, but they do not pass with equal rapidity. Thus, if the two liquids are alcohol and water, one part of alcohol will pass in one direction while 4.2 parts of water pass in the other. This rela- tion, as compared with water, is the osmotic equivalent of the sub- stance, and may be determined not only for liquids, but also for solids in solution. If a layer of a pure solvent (p. 14) is similarly floated upon a solution of a solid in the same liquid, as water upon a solution of sugar, or if the two are separated by a membrane of parchment paper, bladder, or other permeable membrane, the pure solvent will pass into the solution, and the dissolved sugar into the pure solvent until the two liquids have the same concentration, i. e., contain the same quantity of dissolved substance in unit volume throughout. (See solution, p. 14.) Solids in solution differ in the rapidity and completeness with which they undergo osmosis, or dialyse. Substances which crystallize, crystalloids, dialyse easily and with relative rapidity; those which do not form crystals, colloids, do not dialyse, or do so with extreme 10 TEXT-BOOK OF CHEMISTRY slowness. Advantage is taken of this difference to separate crystal- loids from colloids, as salt from albumin. The solution of the two substances is placed in the inner vessel of a dialyser (Fig. 7), whose bottom consists of a layer of parchment paper, and the outer vessel is filled with the pure solvent, water, which is frequently changed as the crystalloid collects in it. Or a section of tubing made of parchment paper, bent into a U shape, may be used as the inner vessel, and suspended in water. Plates of porous earthenware may also be used for dialysis of liquids which would attack an animal or vegetable membrane, but their action is much slower. Semipermeable membranes are membranes which are per- meable to certain diffusible substances, but not to others, usually permeable to water but not to certain substances in solution in it. Such mem- branes exist in animal and vegetable nature and are formed artificially. Pfeffer's membrane is obtained by placing a solution of cupric FIG. 7. . sulphate in a jar of porous earthenware, which is then immersed in a solution of potassium ferrocyanide. A delicate, gela- tinous film of cupric ferrocyanide forms in the walls of the jar where the two solutions come in contact, which constitutes the semipermeable membrane, permeable to water and to saltpeter dissolved in water, but not to sugar or to many other substances in aqueous solution. (See Osmosis, p. 9.) Gases when subjected to pressure diminish in volume progres- sively to an amount limited only by their passage to the form of liquid (p. 15). When relieved of pressure they expand to an un- limited extent. They have, therefore, the volume of the containing vessels, upon whose walls they exert a pressure corresponding to that to which they are themselves subjected, and in all parts of which they have the same density. Boyle-Mariotte Law. If any gas, maintained at a constant tem- perature, is contained in a vessel whose capacity may be altered, as by a piston, the pressure exerted by the gas is found to be doubled when the capacity of the vessel is reduced to one-half; and corre- sponding variations of pressure are observed with other changes in volume : The temperature remaining the same, the volume of a given quan- f 9 as is inversely as the pn\\///v (Boyle-Mariotte Law). Or: HEAT 11 vp=constant. It also follows that the density of a gas is proportion- ate to the pressure. Absorption of Gases. Physical solution (p. 14) of a gas in a liquid is called absorption. The absorption of gases by liquids obeys the following laws: Tlie weight of a gas absorbed by unit volume of a given liquid is proportionate to the gas pressure (Henry's law). The quantity of gas absorbed diminishes with increase of tem- perature. The quantity of a gas which a liquid can absorb is independent of the nature and quantity of other gases which it may already hold in solution. Some solid substances also absorb certain gases. Sometimes such absorption is a physical act, when it is referred to as condensation or absorption. Thus charcoal condenses about 90 times its volume of ammonia. In other cases it is a chemical combination, as when caustic potash absorbs carbon dioxide. SOME PHYSICAL ACTIONS OF CHEMICAL INTEREST. HEAT. The Effects of Heat upon a body are in doing internal work: to raise its temperature, to increase its volume, to change its state of aggregation, or to cause atomic rearrangement, i. e. y chemical change, or in doing external work: in exerting pressure, or in transmitting heat to surrounding bodies. Temperature. The temperature of a body is the extent to which it can impart sensible heat to surrounding bodies. It is not to be confounded with the amount or quantity of heat which the body con- tains. A block of ice just beginning to melt and the same weight of water just beginning to freeze have the same temperature; but heat must be added to the ice to continue its fusion and subtracted from the water to continue its solidification, while during both processes the temperature remains the same in each. Thermometers are instruments for the measurement of tempera- ture. They are usually glass tubes having a bulb blown at one end and closed at the other, the bulb and part of the tube being filled with mercury or with alcohol, whose contraction or expansion indi- cates a fall or rise of temperature. The alcoholic thermometer is used for measuring low temperatures, and the mercurial for temperatures between 40 and 360 C. For higher temperatures instruments called pyrometers, based upon the expansion or variation of electrical conductance of solids, are used. In every thermometer there are two fixed points, determined by experiment. The lower, or freezing point, is fixed by immersing the instrument in melting ice, and marking the level of the mercury in the tube upon the glass when it has become stationary. The higher, 12 TEXT-BOOK OF CHEMISTRY or boiling point, is similarly fixed by suspending the instrument in the steam from boiling water. The instrument is then graduated according to one of three scales: "the Celsius, or Centigrade, the Fahrenheit, and the Reaumur. The freezing point is marked in the Centigrade and Reaumur scales, and 32 in the Fahrenheit. The boiling point is marked 100 in the Centigrade, 212 in the Fahren- heit, and 80 in the Reaumur scale (Fig. 8). The space between the fixed points is divided into 100 equal degrees in the Centigrade scale, into 180 in the Fahrenheit, and into 80 in the Reau- mur. Five degrees Centigrade are therefore equal to nine degrees Fahren- heit. To convert readings in one scale into terms of another the following formulae are used : Centigrade to Fahrenheit: Multiply by 9, divide by 5, and add 32. Ex- ample: 50 C.X9 = 450-f-5 = 90+32 = 122=Ans. Fahrenheit to Centigrade: Subtract 32, multiply by 5, and divide by 9. Example: 5F. 32= 27X5= 135 4-9= 15=Ans. The Centigrade scale is the one now exclusively used for scientific work, and is the only one referred to throughout this volume. Measure of Heat. Heat is measured by its effect in raising the temperature of a given weight of water through a given number of degrees of temperature. Several units have been used, and, unless definitely stated, may easily lead to confusion. The calorie, or therm, or small calorie, or gram-calorie (cal.) is the amount of heat required to raise the temperature of one gram of water from to 1C. (or from 4 to 5C.). The rational calorie (K) is the amount of heat required to raise the temperature of one gm. of water from to 100 C., and is nearly equal to 100 cal. Tin- large calorie, or kilogram calorie (kg:cal.), is based upon the raise of temperature of one kilogram of water from 4 to 5C., and is equal to 1000 cal. Changes in Volume Caused by Heat. As a rule, all substances increase in volume when heated, and diminish in volume on losing heat. There are, however, some exceptions to this rule. Solids and liquids change only slightly in volume by heating or FIG. 8. HEAT 13 cooling.' Thus the coefficient of linear expansion, or ratio of varia- tion in length, of steel is .0000124, and the coefficient of cubic expansion, of variation in volume of mercury is .00018 for 1C. Water on being cooled contracts until its temperature is 4C., be- tween which and it again expands; 4C. is, therefore, the tem- perature of maximum density of water. The changes in volume of gases by heat are of much greater theoretical importance than those in solids and liquids. We have seen that the volume of gas varies with the pressure in obedience to the law: VP=constant. This is only true if the tem- perature remain constant. With variation in temperature the volume of a gas varies according to The Dalton Gay-Lussac Law : The pressure remaining con- stant, the volume of a gas varies directly with the absolute tempera- ture (see below). And, conversely, if the volume remain constant, the pressure varies directly with the temperature. The Law of Charles is to the effect that all gases have the same coefficient of expansion. Absolute Zero Absolute Temperature. As gases contract by ^73 of their volume with each degree of diminution of temperature, a unit volume of gas at on continuous cooling would occupy zero volume at 273. As it is assumed that at that temperature a gas contains no heat 273 is taken as the absolute zero, and degrees of absolute temperature are from that point: T=273-ft. Thus, if the observed temperature, t, be 54 C C. the absolute temperature, T, is 273+54=327. No gas is known to exist at so low a tempera- ture as 273 ; the most resistant, hydrogen, forms a liquid which boils at 252.5, and this temperature can only be slightly lowered by reducing the pressure. The lowest temperature yet attained is 263. Change of State. The state of aggregation of matter depends partly upon the pressure to which it is subjected, but principally upon the amount of heat which it contains. If chemical decomposi- tion does not occur, when heat is added to a solid the motion of its molecules becomes more rapid, and their cohesion becomes less, until the solid becomes a liquid. With the addition of more heat the molecules are more widely separated, their cohesion is reduced to the minimum, and the liquid becomes a vapor. The reverse order of change is produced by abstraction of heat, popularly referred to as "cooling." Solids assume the liquid form by fusion or by solution. Fusion. When a solid, not decomposed by heat, is sufficiently heated it fuses, or melts. Substances which withstand a high tam- perature without fusion are said to be refractory. Every -substance begins to fuse at a certain temperature, which is always the same for a given substance, the pressure remaining constant, and which 14 TEXT-BOOK OF CHEMISTRY remains the same until fusion is complete, whatever the intensity of the heat applied. This temperature is called the fusing point of the substance, and is one of the characters depended upon for its identi- fication, and as a test of its purity. Some substances pass by imper- ceptible changes of gradual softening from the condition of solid to that of liquid, the temperature rising the while, and therefore have no true fusing point ; such are iron and glass. The fusing point is only slightly influenced by the pressure. That of substances which contract on fusion is slightly lowered by increase of pressure, and that of those which expand on fusion is slightly raised. Latent heat. As during the fusion of a solid there is no increase of temperature, notwithstanding that heat is being constantly com- municated to the body, the insensible heat so added, which really does work, is said to become latent. Each substance has its own latent heat, or latent heat of fusion, as it is also called. Thus, if a pound of water at 0C. is placed in one vessel, and in another similar vessel a pound of ice at 0C., and the two vessels then immersed in a large vessel of hot water until the ice is melted, the temperature of the melted ice will be found to be 0C., while the temperature of the water, previously at will be found to be 79.25 C. ; therefore the amount of heat which became latent in melting the ice was 79.25. Solution. A solid, liquid or gas is said to dissolve, or to form a solution in a liquid, when the two substances form a homogeneous liquid. The molecules of the dissolved substance, the solute, are assumed to be uniformly distributed among the molecules of the liquid, which is called the solvent. The act of solution may be a purely physical process, without chemical action between the solute and the solvent, in which case it is referred to as physical or simple solution; or it may consist of two distinct acts, one a chemical action between solute and solvent, and the other the physical solution of the new substance thus pro- duced, in which case it is called chemical solution. A physical solu- tion contains the original substance, which, if a solid, can be recov- ered unchanged by evaporation of the solution, as cupric nitrate from a solution of that salt, however obtained. A chemical solution is, in fact, a physical solution of the new substance formed in the reaction, as cupric nitrate is also left on evaporation of a solution of copper in nitric acid. The quantity of a single solid which can be dissolved in a pure solvent, water for instance, depends upon an inherent relation be- tween solvent and solute, called the solubility, and upon the tempera- ture. The solubility of a solid is one of its distinguishing characters, and each solid has a definite solubility in a given liquid at a given temperature. When no solvent is mentioned, water is understood. HEAT 15 Some, solids, such as calcium chloride, are so readily soluble in water that they absorb sufficient from the air to form a solution. They 'are then said to deliquesce. The solubility of most solids increases with rise of temperature. With some the increase of solubility is proportionate to the rise of temperature, with others the solubility is very slightly affected by variation of temperature, and with others there is a certain tempera- ture of maximum solubility, above which it again diminishes. A solution containing as much of the solute as it is capable of dissolving at the existing temperature is said to be saturated. If made at high temperature it is said to be a hot saturated, and if at the ordinary temperature a cold saturated solution. If a hot satu- rated solution, or one containing more solid than the liquid is capable of dissolving at a lower temperature, be cooled, the solid usually sep- arates in the crystalline form. But if, in the case of certain sub- stances, the solution is allowed to cool while undisturbed, no crystal- lization occurs, and the solution at the lower temperature contains a larger amount of the solid than it could dissolve at that temperature. It is then said to be supersaturated. If a given quantity of liquid be brought in contact with a quantity of solid less than it can dissolve at the existing temperature, the solid dissolves completely to form an unsaturated solution; while if it be in contact with any excess of the solid, such excess remains undissolved, and has no influence upon the solution so long as the temperature remains constant. The solubility of solids is also influenced by the pressure, but to so trifling an extent that it may be disregarded. Dilute solutions are such as contain very small quantities of the solutes. Congelation is the passage of a substance from the liquid to the solid form. It is the reverse of fusion, and takes place at the same fixed temperature, which also remains constant until fusion is com- plete. This temperature is called the freezing point of the substance. Vaporization. The passage of a liquid to an aeriform state may take place from the surface of the liquid only, when the process is called evaporation, or it may take place throughout the mass of the liquid, when it is called ebullition, or boiling. Liquids which evaporate readily, as alcohol, chloroform, ether, are distinguished as volatile liquids; while liquids which do not evaporate, like the fixed oils and glycerol, are called fixed liquids. Gases and Vapors. All aeriform bodies have been converted into liquids under the combined influence of cold and pressure. Aeriform bodies exist in two conditions, dependent upon the temperature. For each gas there is a certain temperature, different for different gases, at and below which the gas can be converted into a liquid by sufficient increase of pressure, without further lowering of temperature, but above which no amount of pressure will cause liquefaction. That temperature is called the critical temperature. 16 TEXT-BOOK OF CHEMISTRY At temperatures above their critical temperatures aeriform bodies are gases, below that temperature they are vapors. When the substance is at its critical temperature there is a certain definite pressure which will cause its liquefaction, which is called its critical pressure. For example: the critical temperature of carbon dioxide is 31.1, and its critical pressure 75.56 atm. When a liquid is heated in a sealed glass tube of sufficient strength to withstand the high pressure attained, a temperature is finally reached when the liquid disappears, and the tube is filled with its vapor, which, having the same volume and weight as the liquid, also has the same density. The temperature at which this occurs, 190 for ether, is clearly the critical temperature of the substance, which is therefore also called its absolute boiling point, and the pressure in the tube is its critical pressure. There is also necessarily a critical density, i. e., the weight of unit volume of the substance at its critical temperature and pressure. Boiling. At a given pressure a liquid begins to boil at a cer- tain temperature, which varies in different liquids, but is always the same in the same liquid. This temperature at 760 mm. of pressure is the boiling point of the liquid. The boiling point remains stationary until the liquid is com- pletely volatilized, whatever the degree of the heat applied. The boiling point is raised by increase of pressure, and depressed by diminution of pressure. Latent heat of vapor. The heat required by a liquid to convert it into a vapor, which is insensible as temperature, is the latent heat of vapor (p. 14). A liquid, in evaporating, absorbs heat. It is by this action that the human body is cooled by the evaporation of perspiration from the skin, that local anesthesia is produced by the evaporation of very volatile liquids, and that cold is produced in refrigerating machines. Liquefaction or condensation is the passage of a gas or vapor to the form of a liquid. It is brought about by chemical action, by cooling, and by compression. Certain salts, such as calcium chloride, absorb vapor of water from the air and with it form a solution. They are then said to deliquesce. When vapors are cooled to a temperature below the boiling point of the liquid from which they originated, at the existing pressure, they are condensed. The process of distillation consists in converting a liquid into a vapor by heat and subsequently condensing the vapor by cooling it. Distillation under reduced pressure is frequently resorted to when it is desirable to avoid a temperature tis high as the boiling point of the liquid. Fractional distillation is the separation of liquids of ELECTRICITY 17 different boiling points by distillation and collection of the several fractions separately. Sublimation is a process differing from distillation in that the material acted upon and the product are solid. Sublimation may or may not be attended by fusion of the original substance. The product is called a sublimate, or, if in fine powder, flowers. Specific Heat. Equal weights of different substances do not pos- sess the same capacity for heat or thermal capacity. Thus if equal weights of water and of mercury are exposed to the same source of heat until the water shall have acquired a temperature of 1 C., the mercury will have a temperature of 30. A given weight of water, therefore, requires 30 times as much heat to raise its temperature through 1 as does an equal weight of mercury, and the capacity for heat of mercury is %o, or 0.0333, that of an equal weight of water. The specific heat of a substance is the amount of heat required to raise the temperature of one kilo, of that substance through one degree Centigrade, expressed in calories. Thus, the specific heat of mercury is 0.0333, as stated above. ELECTRICITY. Certain substances, such as amber, glass, sealing-wax, when rubbed with silk, flannel, etc., acquire the power of attracting light bodies. They are then said to be electrified. If a glass rod is rubbed with silk and approached to a pith ball suspended by a silk thread from a glass support, the pith ball is first attracted, and, after a short contact with the glass, is then repelled. The pith ball has become electrified by contact with the glass, and in this condition the two bodies repel each other. But if now a rod of sealing-wax is rubbed with flannel and approached to the electrified pith ball, the rod will attract the ball. In this state the ball is repelled by the electrified glass, and attracted by the electrified sealing-wax. And, similarly, a pith ball electrified by contact with the electrified sealing-wax will be repelled by the wax and attracted by the glass rod. There are, therefore, two kinds of electricity, one generated in glass by friction with silk, called vitreous or positive ( + ) electricity, the other generated in sealing-wax by friction with flannel, called resinous, or negative ( ) electricity. Bodies similarly electrified repel each other, and bodies differently electrified attract each ofher. Insulators Conductors Ions. If two metal spheres, Supported upon glass rods, and placed about a foot apart, are charged, one with positive, and the other with negative electricity, the spheres will attract each other, but each will retain its charge in dry air. If, now, a glass rod is brought in contact with both spheres at the same time, each still retains its charge as before. But if a brass rod is used in 18 TEXT-BOOK OF CHEMISTRY place of the glass one, the positive and negative electricities neu- tralize each other, and both spheres lose their charges. Glass is an insulator, or non-conductor of electricity; brass is a conductor. Conductors are of two kinds: Conductors of the first order, such as metals, conduct electricity without themselves suffering any change, except elevation of temperature. Conductors of the second order, such as solutions of salts, are substances from which their con- stituents are separated by the passage of electricity through them. The constituents which are thus separated from a conductor of the second order are called ions (pp. 20, 35). Another distinction be- tween the two orders of conductors is that with those of the first order electrical energy only is transported, while with those of the second order matter (the ions) is also transported. Galvanic Electricity. The kinetic energy which is developed in chemical solution of a metal is manifested in part as heat, but also Zn i _ '4- Zn H -- Cu FIG. 9. FIG. 10. in great part in charging the metal with negative electricity, and the solvent with positive electricity. Thus, if a plate of pure zinc is immersed in pure dilute sulphuric acid, the metal becomes charged with negative electricity, and at the same time a part of the zinc goes into solution, its ions carrying a positive charge to the surround- ing liquid (Fig. 9). This action continues for a very short time, until the electric charge so produced balances the "solution pressure" of the metal, i. e., its tendency to dissolve when all action ceases. If, now, a plate of pure copper is also immersed in the acid, the solu- tion pressure of this metal being extremely small, the copper simply becomes charged with positive electricity, and the surround- ing liquid with negative electricity; but no further solution of the zinc occurs (Fig. 10). If, now, the two metal^ plates are connected by a conducting wire, the negative electricity of the zinc and the positive of the copper neutralize each other along the conductor (Fig. 11), the electric charges of the liquid ivcombinc, ;ind solution of the zinc again begins, attended by the generation of constantly renewed electric charges, which constantly tend to neutralize each ELECTRICITY 19 Cu other, producing an electric current, which consists of the passage of positive electricity in one direction, and of negative electricity in the opposite direction. An arrangement of metals and solvent such as that described is called a galvanic cell or element, and a combination of two or more is a galvanic battery. An electric current is produced whenever two metals, or a metal and another conducting solid, are immersed in a liquid in which the two solids have different solution pressures, or when two plates of the same kind of metal are immersed in two liquids in which the metal has different solution pressures, and either floated one upon the other, or separated only by a porous diaphragm. The metal having the higher solution pres- sure is the one which is dissolved in the action of the galvanic ele- ment, and hence is the position of higher potential. The other plate is the position of lower potential. Any wires or other conductors at- tached to the plates are called poles, or leads, or electrodes. The entire system of solvent, plates and outside conductors is called an electric or galvanic circuit. The circuit is said to be closed when there is no break in its continuity, and the current is free to pass. It is said to be open when there is an interruption in its continuity, when the current ceases to pass. The positive electrical current originates at that plate having the greater solution pressure, i. e., the higher potential (the zinc plate, Fig. 11), which is therefore called the generating, or positive plate. It flows through the liquid in the cell to the plate of lower potential (the copper plate), which is therefore called the collecting, or nega- tive plate. From the collecting plate the current passes through the outside conductors of the circuit toward the generating plate. As the positive current leaves the cell from the negative plate, the electrode connected with that plate is of higher potential than that connected with the generating plate, and therefore we have the apparent anomaly that the pole connected with the negative plate is called the positive pole, or the anode, while the pole connected with the positive plate is called the negative pole, or the cathode, or kathode. The positive current, therefore, passing from the position of higher potential to that of lower potential, in many respects resembles the flow of water from a higher to a lower level, or the passage of heat from a higher to a lower temperature. The negative current, on the other hand, passes from lower to higher potential. FIG. 11. 20 TEXT-BOOK OF CHEMISTRY The total current is the sum of the passage of positive charges in one direction and of negative charges in the opposite direction. Electromotive Force Resistance. The difference in potential of an electric generator is referred to as its electromotive force (E. M. R). The strength of the current is directly as the E. M. R, and in- versely as the resistance, and, consequently, the current strength is the E. M. F. divided by the resistance (Ohm's law). We have seen that some substances conduct electricity, while others do not. Conductors also differ in the degree of facility with which they allow the current to pass through them when they are of equal length and of equal cross-section. The resistance of a con- ductor is the degree of opposition which it offers to the passage of the current, and the complement of the resistance is the conductance of the conductor. Eesistance and conductance are clearly inversely proportionate to each other. They depend upon four factors: 1. The special property of conductivity of the material; 2. The length of the conductor ; 3. Its cfcoss-section ; 4. The temperature. The resist- ance is directly as the length, and inversely as the cross-section of the conductor. With metals it is increased, and with salt solutions it is diminished by elevation of temperature. In considering the resistance of a galvanic circuit we have to deal with both internal resistance, i. e., that of the liquid, or liquids, and plates composing the elements, and external resistance, i. e., that of the conducting system outside of the battery. Ohm's Law. This fundamental empirical law is to the effect that: The current strength is directly proportionate to the electro- motive force, and inversely proportionate to the resistance. Or: TT TT C=, and consequently: .R=Q-, and E=RC, also. Electrolysis. We have seen (p. 18) that when a current passes through a conductor of the second order certain constituents, called ions, are separated from the conductor. This occurs with all liquids, whether solutions or fused solids, which are conductors, and the process is called electrolysis, while the substance acted upon, the conductor, is called an electrolyte. The ions are given off, one at each electrode, and entirely unmixed with each other. Those that are given off at the positive electrode, or anode, being attracted thereby, are charged with negative electricity, and are therefore electronega- tive ions, or anions. Those which are given off at the negative electrode, or cathode, are electropositive ions, or cations. Thus, when water is electrolyzed, pure hydrogen is given off at the negative electrode, and pure oxygen at the positive electrode ; and when hydro- chloric acid solution is electrolyzed pure hydrogen is again given off at the negative electrode, and pure chlorine gas at the positive. (See p. 33.) CHEMICAL PHENOMENA 21 Electrical Units. The Ohm is the unit of resistance. It is the resistance offered by a column of mercury, at C., 106.3 cent, long, weighing 14.4521 gm., and having a uniform cross-section of 1 sq. mm. The Megohm, for the measurement of high resistances, is 1,000,000 ohms ; and the Microhm, for the measurement of small resistances, is The Ampere is the unit of current strength. It is a current which will deposit 4.025 gm. of metallic silver in one hour from a neutral solution of silver nitrate (see electrolysis). A milliampere is T oVs- ampere. The Volt is the unit of E. M. F. It is that E. M. F. which, acting steadily through a conductor having a resistance of one ohm will produce a current of one ampere. It is also { Jf the E. M. F. of a standard Clark's cell at 15 C. The Coulomb is the unit of electrical quantity. It is the quan- tity of electricity transferred in one second by a current of one ampere. The Farad is the unit of capacity. It is the capacity of a con- denser charged to a potential of one volt by one coulomb of electricity. The Watt is the unit of energy. It represents the work done by one ampere with a pressure of one volt. One watt per second is equal to T }g of a horse power, or 44.236 foot pounds. The kilowatt, 1000 watts, is the unit used by electrical engineers. CHEMICAL PHENOMENA. Elements. Most substances may 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 is treated with sulphuric acid, it blackens, and a mass of charcoal separates. Upon further examina- tion 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 therefore 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 is a substance which cannot by any known means be split up into other dissimilar bodies. Elements are also called elementary substances or simple sub- stances. The number of well-characterized elements at present known is eighty-three (list p. 27, see also p. 54). Of these eighty-three ele- ments comparatively few enter into the composition of the earth's 22 TEXT-BOOK OF CHEMISTRY crust (with the atmosphere and water), and about ten of them con- stitute approximately 97 or 98 per cent, of the whole. These, with the approximate proportions of each, are : Oxygen ... 50 per cent. Sodium . . .2.5 per cent. Silicon . . . 25 " " Potassium . .2.5 " " Aluminium . . 7 " " Magnesium . .2 " ll Iron . . . . 4 " il Hydrogen . . 1 Calcium . . 3 " " Titanium . . 0.5 " " Total . . 97.5 " " It will be noticed that elements which are of great importance in their relation to life (such as carbon, nitrogen, phosphorus, sulphur, and chlorine) and such valuable and useful elements as gold, silver, and mercury, all combined only furnish about 2.5 per cent, of the total. The elements found in the human body are carbon, hydrogen, oxygen, nitrogen, sulphur, phosphorus, fluorine, chlorine, iodine, silicon, sodium, potassium, calcium, magnesium, lithium, iron, and occasionally traces of manganese, copper, and lead. Compounds are substances made up of two or more elements chemically united with each other in definite proportions. Com- pounds 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 composed of 39.4 per cent, of the light bluish-white metal, sodium, and 60.6 per cent, of the greenish-yellow, suffocating gas, chlorine. Compounds made up of two elements only are called binary compounds; those consisting of three elements, ternary compounds; those containing four elements, quaternary compounds, etc. A mixture is composed of two or more substances, elements or compounds, mingled in any proportion, without chemical action between the constituents. 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. Laws governing the combination of elements. THE LAW OF DEFINITE PROPORTIONS. The relative weights of elementary sub- stances in a compound are definite and invariable. If, for example, we analyze water, we find that it is composed of eight parts by weight of oxygen for each part by weight of hydrogen, and that this proportion exists in every instance, whatever the source of the CHEMICAL PHENOMENA 23 water. If, instead of decomposing, 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 remain after the combination. THE LAW OF MULTIPLE PROPORTIONS. When two elements unite with each other to form more than one compound, the resulting compounds contain simple multiple proportions of one element as compared with a constant quantity of the other. Oxygen and nitrogen, for example, unite with each other to form five compounds. In these the two elements bear to each other the following relations by weight: In the first, 14 parts of nitrogen to 8 X 1 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 quan- tities in which substances unite with the same substance express the relation, or a simple multiple thereof, in which they unite with each other. For example: 71 parts of chlorine combine with 40 parts of calcium, and 16 parts of oxygen also combine with 40 parts of calcium, therefore 71 parts of chlorine combine with 16 parts of oxygen, or the two elements combine in the proportion of some simple multiples of 71 and 16. Mixtures of solids are usually mechanical mixtures, but in some instances the particles of solid mixtures are so intimately inter- mingled that the products are referred to as solid solutions. Indeed, when one constituent predominates largely, there is reason to believe that "dissociation" may occur, as in dilute liquid solutions. Iso- morphous mixtures are crystals obtained by evaporation of mixed solutions of isomorphous compounds, such as the alums, which crys- tals contain the several salts, homogeneously distributed throughout, and in any proportions. Metallic alloys, glasses, and probably dyed fibers are solid solutions. For liquid solutions, see pp. 14, 15. Combination of gaseous elements by volume. The laws of definite proportions, of multiple proportions, and of reciprocal pro- portions (pp. 22, 23), refer to proportions by weight in which ele- ments unite to form compounds. When the proportions by volume in which gaseous elements com- bine to form compounds are compared with each other and with the volumes of the gases produced, all at the same temperature and pres- 24 TEXT-BOOK OF CHEMISTRY sure, simple relations are also found to exist, which are expressed in the laws of Gay-Lussac : 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. It will be noted that hydrogen combines with chlorine, oxygen and nitrogen in the respective proportions by volume of 1:1, 2:1 and 3 : 1. Also, that, while the volume of the compound of hydrogen and chlorine is equal to the sum of the volumes of the components, in the formation of the compound with oxygen there is a condensation in volume of one-third, and of that with nitrogen of one-half. Molecular and Atomic Theories. Postulate of Avogadro, or of Ampere. In explanation of the facts just cited (as well as of many others), it is assumed that matter is not infinitely divisible, that there is a certain smallest quantity of cny substance which can exist in the free state, which is called the molecule. With regard to compound substances (p. 22), this is more than a mere assumption, for, con- sidering the smallest quantity of a compound, however small it may be, it still retains the properties of the compound, but it contains at least two smaller magnitudes, of substances whose properties differ from those of the compound, i. e., those of the elements of which it is composed, and, therefore, it cannot itself be infinitely small. The molecule of hydrochloric acid contains both hydrogen and chlorine, and, however small it may be, the whole must be greater than either of its parts, and it must therefore have a definite magnitude. Almost simultaneously, in 1811 and 1812, Avogadro and Ampere based upon the facts described in the laws of Gay-Lussac the postu- late that equal volumes of gases, under like conditions of tem- perature and pressure, contain equal numbers of molecules. This is usually referred to as the "law" of Avogadro, or of Ampere. It has, however, not the force of a scientific "law," which, like the laws above quoted, is simply a generalized statement of a series of observed and proven facts. This statement, being based upon the undemonstrable assumption of the existence of molecules, is no more capable of proof than is the postulate of Euclid, that "a straight line may be drawn between any two points. ' ' But this postu- CHEMICAL PHENOMENA 25 late of Avogadro has proven itself to be of enormous utility in the development of both chemistry and physics ; and its close and uniform accordance with the results of both physical and chemical investiga- tions, and with the modern kinetic theory of gases lends it addi- tional support. Applying the postulate of Avogadro to the laws of Gay-Lussac, we may translate the first three combinations given in the table on page 24, into the following: 1 molecule chlorine unites with 1 molecule hydrogen, to form 2 mole- cules hydrochloric acid. 1 molecule oxygen unites with 2 molecules hydrogen, to form 2 mole- cules 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 place 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 molecules themselves. And, further, as in these instances each molecule contains two of the smaller quantities, or atoms, the relation between the weights of the molecules must also be the relation between the weights of the atoms, and we may there- fore express the combinations thus: 1 atom chlorine weighing 35.5 unites with 1 atom hydrogen weighing 1 ; 1 atom nitrogen weighing 16 unites with 2 atoms hydrogen weighing 2; 1 atom oxygen 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. Assuming, then, the existence of molecules and atoms, the distinc- tion between them may be expressed in the following definitions: A molecule is the smallest quantity of any substance that can exist in the free state. An atom is the smallest quantity of an elementary substance that can enter into a chemical reaction. The molecule is always made up of atoms, upon whose nature, number and arrangement with regard to each other, the properties of the substance depend. In an elementary substance the atoms compos- 26 TEXT-BOOK OF CHEMISTRY ing the molecules are the same in kind, and usually two in number. In compound 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. When liberated, atoms usually unite to form other molecules, although there are a few elements whose molecules consist of single atoms. The term molecule applies indifferently to elements and com- pounds. Atomic Weight. The atoms of the several elements have definite relative weights; and upon the accurate determination of these all methods of quantitative chemical analysis depend. (See Stoichiome- try, p. 41.) Clearly, as the atomic weights are relative, the weight of one atom of any element may be selected as the unit or base in terms of which the weights of the atoms of other elements may be expressed. Formerly the unit adopted was the weight of one atom of the lightest known substance, hydrogen, and the atomic weight of an element represented the weight of one atom of that element as compared with the weight of one atom of hydrogen. What the absolute weight of an atom of any element may be we do not know. But the determination of the atomic weight of an element depends upon accurate analyses of compounds of that element, and hydrogen, unfortunately, forms compounds amenable to accurate analysis with but few other elements. Oxygen, on the other hand, forms compounds with a great number of other elements, and determinations of atomic weights have usually been made with reference to oxygen in the first instance. If expressed in terms of H = 1, therefore, their accuracy depends upon the correctness of the determination of the ratio be- tween the atomic weights of oxygen and of hydrogen, which, accord- ing to the most recent determination, is H : : : 1 : 15.88 or : H : : 16 : 1.008. But this ratio cannot be considered as being definitely de- cided ; therefore, to avoid the necessity of a recalculation of all atomic weights with increased accuracy of the determination of the ratio : H, chemists have agreed that the atomic weight of oxygen be taken as the base of the system at 16. The following table contains a list of the elements at present known, with their atomic weights, calcu- lated with = 16 (known as the International Atomic Weights). It is recommended that students use the nearest integral numbers: c. g., 108 for silver ; 1 for hydrogen. Molecular Weight. We have seen (p. 25) that in the formation of hydrochloric acid, water, and ammonia, the molecules of hydrogen each contribute one-half of their material to the formation of each of the several new molecules. The molecules of hydrogen must, there- fore, contain at least two atoms each; and it can also be shown that the molecules of chlorine, oxygen, nitrogen and, in fact, of most ELEMENTS 27 ELEMENTS NAME J B >> in Atomic Weight NAME 1 (S c/3 Atomic Weight 0* ll <" Interna- tional (1918) O=i6 %2 3 <~ Interna- tional (1918) O=i6 96.0 144.3 20.2 58.68 222.4 14.01 190.9 16.00 106.7 31.04 195.2 39.10 140.9 226.0 102.9 85.45 101.7 150.4 44.1 79.2 28.3 107.88 23.00 87.63 32.06 181.5 127.5 159.2 204.0 232.4 168.5 118.7 48.1 184.0 238.2 51.0 130.2 173.5 88.7 65.37 90.6 Aluminium Al Sb A As Ba Bi B Br Cd Cs Ca C Ce Cl Cr Co Cb Cu Dy Er Eu F Gd Ga Ge Gl Au He Ho H In I Ir Fe Kr La Pb Li Lu Mg Mn Hg 27 120 40 75 137 208 11 80 112 133 40 12 140 35.5 52 59 93 63 162 168 152 19 157 70 72 9 197 4 163 1 115 127 193 56 83 139 207 175 24 55 200 27.1 120.2 39.88 74.96 137.37 208.00 11.0 79.92 112.40 132.81 40.07 12.005 140.25 35.46 52.0 58.97 93.1 63.57 162.5 167.7 152.0 19.0 157.3 69.9 72.5 9.1 197.2 4.00 163.5 1.008 114.8 126.92 193.1 55.84 82.92 139.0 207.20 6.94 175.0 24.32 54.93 200.6 Molybdenum Neodymium Neon . . . Mv Nu No Ni Nt N Os Pd P Pt K Pr Ra Rh Rb Ru Sa Sc Se Si Ag Na Sr S Ta Te Tb Tl Th Tm Sn Ti W U V Xe Yb Yt Zn Zr 96 144 20 58 222 14 L91 16 107 31 195 39 141 226 103 85 102 150 44 79 28 108 23 87.5 32 181 127 159 204 232 168 118.5 48 184 238 51 130 173 89 65 90 Antimony (Stibium) Argon Nickel . Arsenic . Niton (Radium Emanation ) ... Nitrogen Barium . Bismuth Boron Osmium Bromine . . . Oxygen Palladium Cadmium Caesium Calcium Phosphorus . . . Platinum Carbon Potassium Cerium ( Kalium ) Chlorine . . Praseodymium (c) Radium Chromium Cobalt Rhodium Columbium (a) . . . Copper ( Cuprum ) Dysprosium Erbium Rubidium Ruthenium Samarium Scandium Europium Selenium . Fluorine Silicon Silver (Argentum) Sodium (Natrium) Strontium Gadolinium Gallium Germanium Glucinum ( 6 ) ... Gold (Aurum) .. Helium . . Sulphur .... Tantalum Tellurium Terbium Thallium .... Holmium . Hydrogen Indium Thorium .... Iodine Thulium Iridium . . Tin ( Stannum ) . . . Titanium Iron ( Ferrum ) . . Krypton Tungsten (Wolframium) . Uranium Lanthanum Lead (Plumbum) , Lithium . . Vanadium Lutecium Magnesium Manganese Mercury (Hydrargyrum) Xenon Ytterbium (d) Yttrium Zinc Zirconium (a) Also formerly known as Niobium, Nb. (&) Also formerly known as Beryllium, Be. (c) Also formerly known as Didymium, Di. (d) Also known as Neoytterbium. 28 TEXT-BOOK OF CHEMISTRY other elements also contain at least two atoms each. There are excep- tions, however, in the cases of several metals, whose molecules con- sist of single atoms. Taking the weight of one atom of hydrogen as the basis of mo- lecular as well as of atomic weights the molecular weight of a substance is the weight of its molecule as compared with the weight of an atom of hydrogen. It is immaterial to this definition what the absolute weight of the hydrogen atom may be, or whether it is con- sidered as weighing 1.000 or 1.008. The molecular weight is also, obviously, the sum of the weights of the atoms making up the molecule. A ready method for determining the molecular weights of sub- stances existing or obtainable in the aeriform state is based upon the postulate of Avogadro. The specific gravity of a gas or vapor re- ferred to hydrogen is the weight of any given volume as compared with the weight of an equal volume of hydrogen (p. 3). But equal volumes contain equal numbers of molecules (p. 24), and the relation of weights, the sp. gr., of the whole is the same for any equal frac- tions, down to the molecules, and therefore this specific gravity is the weight of a molecule of the gas as compared with that of a molecule of hydrogen; and as the molecule of hydrogen contains two atoms, while one atom is the unit of comparison, it follows that the specific gravity of a gas compared with hydrogen, multiplied by two, is its molecular weight. For example, the gas acetylene and the liquid benzene each con- tain 92.31 per cent, of carbon, and 7.69 per cent, of hydrogen ; which is equivalent to 24 parts, or two atoms of carbon; and 2 parts, or two atoms of hydrogen. The sp. gr. of acetylene, referred to hydro- gen = 2, is 13 ; its molecular weight is, therefore, 26, 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, therefore, 78, and its molecule contains six atoms of carbon and six atoms of hydrogen. When a substance is not capable of being volatilized, its molecular weight may be obtained from certain properties of its solutions, which will bo considered in connection with organic chemistry (see p. 195). The vapor densities of comparatively few elements are known: Vapor Atomic Molecular Density Weight Weight Hydrogen 1 1 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 Iodine . 127 127 254 VALENCE 29 Vapor Atomic Mole'cular Density Weight Weight Phosphorus 63 31 124 Arsenic 150 75 300 Nitrogen 14 14 28 Potassium 39 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 tlie molecules of these elements consist of two atoms. Noticeable discrepancies 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, there- fore, supposed to contain four atoms. Those of cadmium, zinc and mercury contain but one atom. Gram-molecule Mol. That quantity of a substance whose weight is represented by its molecular weight expressed in grams is called a gram-molecule, or mol; as 32 gms. oxygen, 70.9 gms. chlorine, 18.016 gms. water. The mol is a quantity both theoretically and practically important. We have now to consider it in connection with certain facts already referred to. Molecular Volume. The molecular volume of a gas or liquid is the volume occupied by one 'mol of the substance under normal conditions. According to the postulate of Avogadro (p. 24), equal molecular weights (mols) of all gases must occupy the same volume, at the same temperature and pressure, or, in other words: the molecular volume (Vm) of gases is a constant quantity. The molecular volume of a gas is the product of its specific volume (Vs), i.e., the vol- ume in cc. which 1 gm. occupies at and 76 cm., and its molecular weight. Thus Weight of 1 L in gms. at and 76 cm. Vs. Mw. VsxMw, in L. Hydrogen 0.08988 11,111 2.016 22.399 Oxygen 1.4291 699.7 32.000 22.390 Nitrogen 1.2507 799.5 28.080 22.450 The volume occupied by 1 mol of a gas at and 76 cm. is 22.4 liters. Consequently the weight, p, of any given volume of gas, v, in liters, reduced to normal conditions is: p= *' ^ 2 * V > an d tne volume, 22 4 T) in liters, of any given weight of gas is: v="T' - JVJL\V. Valence or atomicity. It is known that the atoms of different elements possess different capacities for combining with and for re- placing atoms of hydrogen. Thus: 30 TEXT-BOOK OF CHEMISTRY 1 atom of chlorine combines with 1 atom of hydrogen. 1 atom of oxygen combines with 2 atoms of hydrogen. 1 atom of nitrogen combines with 3 atoms of hydrogen. 1 atom of carbon combines with 4 atomc of hydrogen. The valence, atomicity, or equivalence of an element is the saturating capacity of one of its atoms as compared with that of one atom of hydrogen. Elements may be classified according to their valence into Univalent elements, or monads ". . Cl' Bivalent elements, or dyads 0" Trivalent elements, or triads B"' Quadrivalent elements, or tetrads C iv Quinquivalent elements, or pentads P v Sexivalent elements, or hexads W Elements of even valence, i. e., those which are bivalent, quad- rivalent, or sexivalent, 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, phos- phorus forms two chlorides, one containing 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 pentachloride, 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 compounds in which the element has a higher valence than that which might be considered the max- imum to-day. The second supposition notwithstanding 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, therefore, of the valence of an element, we must not consider it as an absolute quality of its atoms, but simply as their combining capacity in the particular class of com- pounds under consideration. Indeed, compounds are known in whose molecules the atoms of one clement exhibit two distinct valences. Thus, ammonium cyanate (H 4 ==N C = N) contains two atoms of nitrogen : one in the ammonium group is quinquivalent, one in the acid radical is trivalent. SYMBOLS 31 TABLE OF THE VALENCES OF SOME OF THE COMMONER ELEMENTS AND RADICALS. Uiiivalent Bivalent Trivalent Quadrivalent Quinquivalent Sexivalent H F Cl Br I Li Na K Ag Cu (ous) Hg (ous) S Mn (ous) Fe (ous) Pb Sn (ous) Ca Ba Mg Zn Cu (ic) Hg (ic) N P As Sb B Fe (ic) Bi Al c Si S Pt Sn (ic) N P As Sb S w (P0 4 ) (OH) (NO,) (NH 4 ) (CN) (C 2 H 3 2 ) (S0 4 ) (CO.) The chemical equivalent, or equivalent weight, of an element is the weight of that element capable of combining with unit weight of hydrogen (or chlorine). It is, therefore, its atomic weight divided by its valence. We have seen (p. 25) that 35.5 parts by weight of chlorine combine with 1 part by weight of hydrogen, 16 of oxygen with 2 of hydrogen, and 14 of nitrogen with 3 of hydrogen. Chlorine being univalent, oxygen bivalent and nitrogen trivalent, their equivalent weights are, therefore, respectively: 35.5-f-l=:35.5, 16-^-2=8, and 14-^3=4.67. (See also p. 37.) A gram-equivalent of an element is a quantity of that element whose weight in grams is equal to its molecular weight divided by its valence. Thus 23 gms. of sodium, and 65.4-T-2=32.7 gins, of zinc, are gram equivalents of those metals. Symbols, Formulae, Equations. Symbols are conventional abbreviations of the names of the elements ; 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 are more than two elements whose names begin with the same letter, the single-letter symbol is reserved for the commonest element. Thus, we have ten 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 ; Copper, Cu (Cuprum), etc. These symbols do not indicate simply an indeterminate quan- tity, but represent one atom of the corresponding element. 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 32 TEXT-BOOK OF CHEMISTRY atom of hydrogen; 2C1, two atoms of chlorine; C 4 , four atoms of carbon, etc. What the symbol is to the element, the formula is to the com- pound. By it the number and kind of atoms of which the molecule of a substance is made up are indicated. The simplest kind of formula; are what are known as empirical formulae, which indicate only the kind and number of atoms which form the compound. Thus, HC1 indicates a molecule composed of one atom of hydrogen united with one atom of chlorine; 5H 2 0, 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 parentheses; thus, A1 2 (S0 4 ) 3 means twice Al and three times S0 4 . For other varieties of formula?, see pp. 47, 48. 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 2KOH+H 2 S0 4 =K 2 S0 4 +2H 2 means, when translated into ordinary language: two molecules of potassium hydroxide, each composed of one atom of potassium, one atom of hydrogen, and one atom of oxygen, and one molecule of sulphuric acid, composed of two atoms of hydrogen, one atom of sulphur, and four atoms of oxygen, have reacted upon eacli other and have produced one molecule of potassium sulphate, composed of two atoms of potassium, one atom of sulphur, and four atoms of oxygen, 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 always be the same as that occurring after it. In writing equations, they should always be proved by examining whether the half of the equation before the equality sign contains the same number of each kind of atom as that after the equality sign. If it does not, the equation is incorrect. The word reaction is used in chemistry with two distinct mean- ings: As applying to the action mentioned above, it refers to the mutual action of two substances upon each other. In the other meaning it refers to the action of substances upon certain organic pigments. Thus, the reaction of a substance is acid, when it turns ELECTROLYSIS 33 blue litmus red; alkaline, when it turns reddened litmus blue; amphoteric, when it turns red litmus blue and blue litmus red; and neutral, when it has no action upon either blue or red litmus. Chemical reactions in the former sense are either: 1. Combinations, also called syntheses, in which elements or simpler compounds unite to form more complex molecules, as when 2H 2 +0 2 = H 2 2. Decompositions, also called analyses, processes the reverse of combinations, as when 2H 2 0=2H 2 +0 2 ; and 3. Double decompositions, or matatheses, when two substances mutually react upon each other with formation of new substances, as when 2KOH+H 2 S0 4 =K 2 S0 4 +2H 2 When one of the reagents in a double decomposition is water, the process is called hydrolysis (see p. 64). Special varieties of these several kinds of reaction, which are sufficiently distinctive, have received distinguishing names, such as condensations, etc., and will be considered later. There also occur, notably with the compounds of carbon, instances of (4) Atomic rearrangement, or transposition, in which the com- position remains the same, but the constitution (p. 46) is changed: as when ammonium isocyanate, :C :N.NH 4 is converted into urea, H 2 .NCO.NH 2 . Electrolysis. We have seen (p. 20) that when hydrochloric acid is electrolyzed, hydrogen is given off at the negative pole, and is therefore electropositive, while chlorine is given off at the positive pole, and is therefore electronegative. But if a compound of chlorine and sulphur is electrolyzed, chlorine is given off at the negative elec- trode, and is therefore electropositive. Chlorine is consequently elec- tropositive to sulphur, and electronegative to hydrogen. The results of electrolysis of binary compounds of many elements have shown that oxygen is electronegative, and the alkali metals (p. 149) are electropositive to all other elements with which they form binary compounds. If the elements are arranged in an electro- chemical series, with oxygen at the electronegative end and caesium at the electropositive end, and if the other elements are placed in the series in such positions that each will be between oxygen and all other elements toward which it is electronegative, it will be found that hydrogen will occupy a position about midway between the two ends, but nearer to the electronegative, and that the elements of the acidulous class (p. 52) will be placed between hydrogen and oxygen, while the metals will be placed to the electropositive side of 34 TEXT-BOOK OF CHEMISTRY hydrogen. See the accompanying arrangement in the shape of a horseshoe. ELECTRONEGATIVE ELECTBOPOSITP Oxygen Sulphur Caesium Rubidium Nitrogen Potassium Fluorine Sodium Chlorine Lithium Bromine Barium Iodine Strontium Selenium Calcium Phosphorus Magnesium Arsenic Beryllium Chromium Yttrium Vanadium Erbium Molybdenum Aluminium Tungsten Zirconium Boron Thorium Carbon Cerium Antimony Didymium Tellurium Lanthanum Tantalum Manganese Columbium Zinc Titanium Iron Silicon Nickel Hydrogen Cobalt Gold Thallium Osmium Cadmium Iridium Lead Platinum Indium Rhodium Tin Ruthenium Bismuth Palladium Uranium Mercury Copper Silver" Arbitrarily, elements electronegative to hydrogen are con- sidered as electronegative elements, those electropositive to hydro- gen as electropositive elements. A similar separation takes place in the electrolysis of compounds containing more than two elements, one element being liberated at one pole and the remaining group of elements separating at the other. This primary decomposition is generally modified, as to its final products, by subsequent chemical reactions, called secondary actions. When, for example, a solution of potassium sulphate is elec- trolyzed, the liquid surrounding the positive electrode becomes acid in reaction, and gives off oxygen. At the same time the liquid at the negative side becomes alkaline, and gives off a volume of hydrogen double that of the oxygen liberated. In the first place potassium sulphate, which consists of potassium, sulphur and oxygen, yields on primary separation electropositive potassium, which separates at the negative pole; and, an electronegative group of sulphur and oxygen, which goes to the positive pole : 2K 2 S0 4 =2K a +2S0 4 ELECTROLYSIS 35 The pcftassium liberated immediately decomposes the surround- ing water, forming caustic potash, to which the alkaline reaction is due, and hydrogen, which is liberated: 2K 2 +4H 2 0=4KOH+2H 2 The sulphur-oxygen group at the positive pole also immediately reacts with water to form sulphuric acid, and oxygen is liberated: 2S0 4 +2H 2 0=2H 2 S0 4 +0 2 one molecule of oxygen being liberated for every two of hydrogen. The name ion was first applied by Faraday to the primary products of electrolysis; and those which separate at the positive electrode, or anode, are called anions, while those which separate at the negative electrode, or cathode, are called cations. Thus, potas- sium sulphate yields the cation K, and the anion S0 4 . Cations are designated by the plus sign, anions by the minus sign. Thus: + + K 2 S0 4 =K K-f-S0 4 , or, better, the cations, as well as their valences, are designated by the proper number of dots placed after the symbol, thus, H", Ca" and the anions similarly by prime marks, thus, OH', S0 4 ", and As0 4 "'. Hydrogen, the metals, and basic radicals are cations; Jiydroxyl and the acid residues are anions. The residues of acids are compound ions, that is, ions consisting of more than one element. According to the earlier views of electrolysis, the decomposition of the molecule into its ions was considered to be a result of the action of the galvanic current. According to the theory of Arrhenius, dissociation into ions, or ionization, occurs when the electrolyte is dissolved. A solution of potassium chloride contains not only the molecular KC1, but also the cation K* and the anion Cl', and the action of the current is to separate these, already liberated, ions at the respective electrodes. It is assumed that the hydrogen and metallic ions are charged with positive electricity, and the hydroxyl and acid-residue ions with negative electricity, and therefore the former are attracted to the negatively charged cathode, and the latter to the positively charged anode. We have seen that when an aqueous solution of an acid is elee- trolyzed, hydrogen is always given off at the cathode. Although hy- drogen exists in innumerable compounds other than acids, it is only from them that it is so separated, and only from them when in solution. That this hydrogen does not originate from the water is shown by the fact that perfectly pure water is neither a conductor nor an electrolyte. It is only in solutions of acids (or in solutions of acid salts or esters, which still retain acid properties), therefore, that hydrogen exists in the ionized form, hydrion. Hydrion also dif- fers from molecular or atomic hydrogen in other respects. It is only known in solution, while molecular hydrogen is almost insoluble in 36 TEXT-BOOK OF CHEMISTRY water. It reddens litmus and is replaceable by metals, properties not possessed by either atomic or molecular hydrogen. Similarly, when solutions of bases are electrolyzed hydroxvl, OH, is always pro- duced as a primary product at the anode. And, here again, although hydroxyls exist in many compounds other than those having basic properties, it is only from solutions of these that hydroxyl is thus separated, as only their solutions contain the ion, hydroxidion. And hydroxiodion differs further from hydroxyl in that it is only known in solution, that it blues reddened litmus, and that it is replaceable by acid residues. In the electrolysis of an oxyacid (see below) that group which is primarily separated at the positive electrode is called the residue of the acid. (See p. 46.) Acids, Bases and Salts. All ternary and quaternary mineral substances have one of three functions. The function of a substance is its chemical character and relationship, and indicates certain gen- eral properties, reactions and decompositions which all substances having the same function possess and undergo alike. Thus in mineral chemistry we have acids, bases and salts; and in organic chemistry, alcohols, aldehydes, acids, ketones, esters, etc. An acid is a compound of an electronegative element or residue with hydrogen, which hydrogen it can part with in exchange for an electropositive element, without formation of a base. An acid has also been defined as a compound body which evolves water by its action upon pure caustic soda or potash. This latter definition is undesirable in view of the existence of certain zinc and aluminium compounds (pp. 175, 178). No substance which does not contain hydrogen can, therefore, be called an acid. An acid has also boon defined as a compound yielding hydrion on electrolysis. The basicity of an acid is the number of replaceable hydrogen atoms in its molecule. A monobasic acid is one containing a single replaceable atom of hydrogen, as nitric acid, HN0 3 : a dibasic acid is one containing two such replaceable atoms, as sulphuric acid, H 2 S0 4 ; a tribasic acid is one containing three replaceable hydrogen atoms, as phosphoric acid, H 3 P0 4 . Polybasic acids are such as contain more than one atom of replaceable hydrogen. Hydracids are acids containing no oxygen ; oxyacids contain both hydrogen and oxygen. The term base is regarded by many authors as applioablo to any compound body capable of neutralizing an acid. It is, however, moiv consistent with modern views to limit tho application of the name to such ternary compound 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 electropositive element ACIDS, BASES AND SALTS 37 or radical ; or as compounds of such elements or radicals with one or more groups, OH. Being thus considered as derivable from water, they are also known as hydroxides. They have the general formula, M(OH)n. They are monatomic, diatomic, triatomic, etc., accord- ing as they contain one, two, three, etc., groups oxhydryl, or hy- droxyl (OH). As acids having one, two or three, etc., atoms of re- placeable hydrogen are designated as monobasic, dibasic, or tribasic acids, etc., so bases having one replaceable hydroxyl are spoken of as monacid bases, those having two as diacid bases, etc. A base has also been defined as a compound yielding hydroxidion on electrolysis. The atomicity of a compound is the number of hydroxyls in its molecule, which it may lose by their combination with the hydro- gen of acids. Bases are said to be monatomic, monohydric or monacid ; diatomic, dihydric or diacid, etc., according as the number of their hydroxyls is one, two, etc. A double decomposition is a reaction in which both of the reacting compounds are decomposed to form two new compounds. Thiobases, or hydrosulphides, are compounds in all respects resembling the bases, except that in them the oxygen is replaced by sulphur. An equivalent of an acid or base is a quantity thereof equal to one molecule, divided by the basicity or acidity; or that propor- tionate quantity of its molecular weight which contains only one basic hydrogen atom or only one acid displaceable hydroxyl. Thus, a molecule and an equivalent of potassium hydroxide, KOH, both weigh 56.11 ; a molecule of sulphuric acid, H,S0 4 , weighs 98.08, and an equivalent 49.04. A gram-equivalent (gm :eq.) of any substance is a quantity thereof whose weight is that of its equivalent, expressed in grams. Concentration. By the "concentration" or "strength" of a solu- tion is understood the amount of the solute in unit volume of the solution (not of the solvent). Various units are used for the ex- pression of concentration: In percentage solutions, strictly, both solvent and solute are taken in parts by weight. Thus, a 4 per cent, solution of scdium chloride is made with 4 gms. NaCl and 96 gms. H 2 0. Volume: per cent, solutions are usually more convenient: A 4- per cent, solution of sodium chloride is made by dissolving 4 gms. NaCl in a volume of water such that the finished solution measures 100 cc. The difference between per cent, and v per cent, solutions is more marked with solvents other than water. While per cert, solutions are independent of temperature, v per cent, solutions have the concentration indicated only at the temperature for which they are made, which is usually 18 C. Normal solutions are of two kinds: Molecular-normal, which 38 TEXT-BOOK OF CHEMISTRY contain one gram-molecule in a liter of solution, and Equivalent- normal, which contain one gram-equivalent in a liter. Thus, one liter of M-N solution of sulphuric acid contains 98 gms. H 2 S0 4 , and one liter of Eq-N solution 49 gms. Usually "normal" solutions are molecular-normal, except solutions used in volumetric analysis, which are equivalent-normal, whole or fractional. Decinormal solu- tions ( j contain Mo gm :mol. or gm :eq. per liter, etc. Standard solutions are solutions of some fixed volume-concentration, which may be of any value desired for the use intended. Salts are substances formed by the substitution of electro- positive, or basylous, elements for a part or all of the replaceable hydrogen of acids. They are formed, therefore, when bases and acids enter into double decomposition. As salts are produced by double decomposition between acids and bases, the latter play as much part in the formation of salts as do the former, and we may also consider*the salts as substances formed by the substitution of acid residues (p. 46) for a part or all of the hydroxyl of bases. Salts have also been defined as compounds formed by the union of the anion of an acid and the cation of a base. It will be seen from the above that in some salts the hydrogen of the acid is only partly replaced, as in baking soda: OC^Qjj a . Such salts are called bi salts or acid salts. There exist, also, salts in which a portion of the hydroxyl of the bases is retained. Such salts are called basic salts, e. g., basic lead nitrate N0 3 PbOH. (See p. 45.) The term salt, as used at present, applies to the compounds formed by the substitution of a basylous element for the hydrogen of any acid; and indeed, as used by some authors, to the acids themselves, which are considered as salts of hydrogen. It is probable, however, that eventually the name will be limited to such compounds as cor- respond 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 consist of hydrogen, united with one other element, on the one hand ; and the oxysalts, the salts of the oxyacids, *. e., those into whose composition oxygen enters, 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 ivhen the basylous element be- longs 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 cor- responding to the hydracids, binary compounds of chlorine, bromine, iodine and sulphur. There is, on the other hand, a large class of ele- ments the members of which are incapable of forming salts corre- ACIDS, BASES AND SALTS 39 spending to the oxyacids. No salt of an oxyacid with any one of the elements usually classed as metalloids (excepting hydrogen) has been obtained. Haloid salts may be formed by direct union of their constituent elements; oxysalts are never so produced. Action of Acids and Bases on Salts, and of Salts on each other. (1) If an acid is added to a solution of a salt whose acid it nearly equals in chemical activity, the salts of both acids and the acids themselves will probably exist in the solution, provided both acids and salts are soluble. Thus, if sulphuric acid is added to a solution of potassium nitrate, the solution will contain potassium sulphate and nitrate, and sulphuric and nitric acid : 2H 2 S0 4 +3KN0 3 =K 2 S0 4 +KN0 3 +H 2 S0 4 +2HN0 3 (2) If an acid is 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 salts and acids being soluble. Thus, if sulphuric acid is added to a solution of sodium acetate, the solution will contain sodium sulphate and acetic acid: H 2 S0 4 +2NaC 2 H 3 2 :=Na 2 S0 4 +2HC 2 H 3 2 (3) 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. Thus, if potassium sulphate and sodium nitrate are dissolved in the same solution it will contain potassium and sodium sulphates and potassium and sodium nitrates: 3K 2 S0 4 +3NaN0 3 =r2K 2 S0 4 +Na 2 S0 4 +2KN0 3 +NaN0 3 , or in some other proportion. In the light of the hypothesis of ionization, the statements 1, 2 and 3, while applying to that portion of the compounds which remain un-ionized, may be better expressed in the one: Solutions of acids, bases and salts contain all the free ions. Thus, in the example given in 3, the solution contains K, Na, S0 4 , and N0 3 . (4) If to a solution of a salt, whose acid is insoluble in the solvent used, an acid is added, capable of forming a soluble salt with the basylous element, such soluble salt is formed and the acid is deposited. Thus, if sulphuric acid is added to an aqueous solu- tion of sodium stearate, stearic acid will be deposited and sodium sulphate formed: H 2 S0 4 +2NaC 18 H 8 A=Na 2 S0 4 +2HC 18 H 8B 2 (5) If to a solution of a salt an acid is added which is capable of forming an insoluble salt with the base, such insoluble salt is formed and precipitated. Thus, if sulphuric acid is added to a solu- 40 TEXT-BOOK OF CHEMISTRY tion of barium nitrate, barium sulphate is precipitated and nitric acid liberated: H 2 S0 4 +Ba (N0 3 ) 2 =BaS0 4 +2HN0 3 (6) 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. Thus, if potassium hydroxide is added to a solution of cupric sulphate, cupric hydroxide is precipitated and potassium sulphate formed : 2KOH+CuS0 4 =Cu ( OH) 2 +K 2 S0 4 (7) If a base is 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. Thus if solutions of barium hydroxide and of potassium sulphate are mixed, barium sulphate is precipitated and the solution contains potassium hydroxide : Ba(OH) 2 +K 2 S0 4 =BaS0 4 +2KOH; or if solutions of barium hydroxide and silver sulphate are mixed both barium sulphate and silver hydroxide will be precipitated: Ba(OH) 2 +Ag 2 S0 4 =BaS0 4 +2AgOH, and if the substances are used in the proportions given in the equation pure water will remain. (8) 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 insoluble salt is prec 'pitated. Thus, if solutions of barium nitrate and of sodium sulphate are mixed, barium sulphate is precipitated and sodium nitrate formed: Ba (N0 3 ) 2 +Na 2 S0 4 =BaS0 4 +2NaN0 3 The statements 4 to 8 may ~be summarized in tlie statement: When solutions of acids, bases or salts any of whose ions are capable of uniting to form an insoluble compound are mixed, such insoluble compound is formed and precipitated. (9) 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 is added, the fixed salt is formed and the volatile acid expelled. Thus, with the application of heat, sulphuric acid expels nitric acid from sodium nitrate to form sodium sulphate : H 2 S0 4 +2NaN0 3 =2HN0 3 +Na 2 S0 4 (10) Similarly, n volatile base is expelled from its salts by a fixed one. Thus potassium hydroxide and ammonium chloride form ammonia, water and potassium chloride: KOH+NH 4 C1=KC1+NH 3 +H 2 STOICHICMETRY 41 Stoidiiometry in its strict sense refers to the law of definite pro- portions, and to its applications. In a wider sense, the term applies to the mathematics of chemistry, i. e., to those mathematical calcu- lations by which the quantitative relations of substances acting upon each other, and of the products of such reactions are determined. A chemical reaction can -always be expressed by an equation, which, as it represents not only the nature of the materials involved, but also the number of molecules of each, is a quantitative as well as a qualitative statement. Let it be desired to determine how much sulphuric acid will be re- quired to completely decompose 100 parts of sodium nitrate, and what will be the nature and quantities of the products of the decom- position. First the equation representing the reaction is constructed : H 2 S0 4 -f 2NaN0 3 Na 2 S0 4 -f 2HN0 3 Sulphuric acid. Sodium nitrate. Disodic sulphate. Nitric acid. which shows that one molecule of sulphuric acid decomposes two molecules of sodium nitrate, with the formation of one molecule of sodium sulphate and two of nitric acid. The quantities of the dif- ferent substances are, therefore, represented by their molecular weights, or some multiple thereof, which are in turn obtained by adding together the atomic weights of the constituent atoms: H 2 S0 4 -f 2NaN0 3 Na 2 SO 4 -f 2HN0 3 1X2= 2 23X1=23 23X2=46 32X1=32 14X1 = 14 32X1=32 14x1 = 14 16X4=64 16X3=48 16X4=64 16X3=48 98 85X2=170 142 63x2=126 Consequently, 98 parts H 2 S0 4 decompose 170 parts NaN0 3 , and produce 142 parts Na 2 S0 4 , and 126 parts HN0 3 . To find the result as referred to 100 parts NaN0 3 , we apply the simple proportion : 170: 100: : 98: 57.6457.64 = parts H 2 S0 4 required. 170: 100: : 142: 83.5383.53 = " Na 2 S0 4 produced. 170: 100:: 126: 74.11 74.11 = " HN0 3 As in writing equations, the work should always be proved by adding together the quantities on each side of the equality sign, which should equal each other: 98+170=268=142+126=268, or 57.64+100=157.64=83.53+74.11=157.64. In determining quantities as above, regard must be had to the purity of the reagents used, and, if they be crystallized, to the amount of water of crystallization (see p. 8) they contain. Let it be desired to determine how much crystallized cupric sul- phate can be obtained from 100 parts of sulphuric acid of 92 per 42 TEXT-BOOK OF CHEMISTRY cent, strength. As cupric sulphate crystallizes with five molecules of water of crystallization the reaction occurs according to the equation : H 2 S0 4 + CuO + 4H 2 CuSO,5Aq. Sulphuric acjd. Cupric oxide. Water. Cupric sulphate. 63 1X 2 = 2 63x1=63 1X2= 2 16 16X1=16 32X1=32 32X1=32 16X4=64 16X4=64 18X5=90 98 79 18X4=72 249 98+79+72=249 98 parts of 100 per cent. H 2 S0 4 will produce, therefore, 249 parts of crystallized cupric sulphate. But as the acid liquid used contains only 92 parts of true H 2 S0 4 , in 100; 100 parts of such acid will yield 233.75 parts of crystallized sulphate, for 98 : 92 : : 249 : 233.75. Let the problem be to determine what percentage of silver is contained in a silver coin. Advantage is taken of the formation of the insoluble silver chloride, A piece of the coin is chipped off and weighed: weight of coin used=2,5643 grams. The chip is then dissolved in nitric acid, forming a solution of silver nitrate. From this solution the silver is precipitated as chloride, by the addi- tion of hydrochloric acid, according to the equation: AgN0 3 + HCl = AgCl + HN0 8 Silver nitrate. Hydrochloric acid. Sliver chloride. Nitric acid. 108X1=108 1 108 1X1= 1 14X1= 14 35.5 35.5 14x1 = 14 16X3= 48 16X3=48 170 36.5 143.5 63 170+36.5=206.5=143.5+63. The silver chloride is collected, dried and weighed : Weight of coin used 2.5643 grams. Weight of AgCl obtained 3.0665 " as 143.5 grams AgCl contain 108 grams Ag 143.5 : 108 :: 3.0665 : 2.30782.5643 grams of the coin contain 2.3078 grams of silver or 90 per cent. 2.5643 : 100 : : 2.3078 : 90. Nomenclature. The names of the elements are mostly of Greek derivation, some are of Latin origin ; some of Gothic origin and others are derived from modern languages. Very little system has been fol- lowed in naming the elements, beyond applying the termination ium to the metals, and in or an to the non-metals ; and even to this rule there are exceptions, such as a metal called manganese and a non- metal called sulphur. NOMENCLATURE 43 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 remained small, the use of these fanciful appellations gave rise to comparatively little inconvenience. In these later days, however, when the number of compounds known to exist, or whose existence is shown by approved theory to be pos- sible, is practically infinite, some systematic method of nomenclature has become absolutely necessary. The principle of the system of nomenclature at present used is that the name shall convey 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 electropositive, followed by that of the more electronegative, in which the termination ide has been substituted for the termination in, on, ogen, ygen, orus, ium, and ur. For example : the compound of potassium and chlorine is called potas- sium chloride, that of potassium and oxygen potassium oxide, that of potassium and phosphorus potassium phosphide. In a few instances the older name of a compound is used in prefer- ence to the one which it should have under the above rule; such are ammonia, NH 3 ; water, H 2 0. When, as frequently happens, two elements unite with each other to form more than one compound, these are usually distinguished from each other by prefixing to the name of the element varying in amount the Greek numeral corresponding to the number of atoms of that element, 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 2 is the standard of com- parison, and consequently the names are as follows : N 2 O =Nitrogen monoxide. NO (=N a O,)=Nitrogen dioxide. N 2 O 3 ^Nitrogen frioxide. N0 2 ( =N 2 O 4 ) =Nitrogen tetroxide. N 2 O 5 =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 electronegative element, and in ic in that containing the greater portion ; thus : S0 2 =Sulphurows oxide. S0 3 = Sulphuric oxide. HgCl=Mercurows chloride. HgCl 2 =Mercuric chloride. 44 TEXT-BOOK OF CHEMISTRY This method, although used to a certain extent in speaking of com- pounds composed of two elements of Class III (see p. 52), is used chiefly in speaking of binary compounds of elements of different classes. In naming the oxyacids the word acid is used, preceded by the name of the electronegative clement other than oxygen, to which a prefix or suffix is added to indicate the degree of oxidation. If there are only two, the least oxidized is designated by the suffix ous, and the more oxidized by the suffix ic, thus : HN0 2 =NitroMs acid. HNO 3 =Nitric acid. If there are more than two acids, formed in regular series, the least oxidized is designated by the prefix liypo 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 : HC10=/f7ypochloroi 2Fe 3 4 -f 8H 2 Iron. Water. Trlferric tetroxide. Hydrogen. If we start with pure iron and vapor of water the reaction will proceed according to the equation read from left to right until the proportion of hydrogen and water vapor present has reached a cer- tain ratio, when the action will cease, and the system will be in equilibrium. Starting with pure oxide of iron and hydrogen, on the other hand, the reaction will proceed according to the equation read from right to left, and will cease when the ratio of hydrogen to water vapor will have acquired the same value as that reached in the first instance. As the condition of equilibrium reached in the two cases is the same when produced by proceeding in either direction, it is one of real equilibrium, and, as might be expected, if a mixture of iron and oxide of iron be heated in an atmosphere composed of hydrogen and CLASSIFICATION OF ELEMENTS 51 water vapor in the proportion reached in either of the two former reactions, no change whatever will occur. Mass Action. The example of a reversible reaction given above was one in a heterogeneous system, composed of solids and gases. As an example of a reaction of this kind occurring in a homogeneous system, a solution, we may consider that represented by the following equation : CH 3 .COOH + CH 3 .CH 2 OH < > CH 3 .COO(C 2 H 5 ) -f H 2 O. Acetic acid. Ethylic alcohol. Ethyl acetate. Water. If we start with ethyl alcohol and acetic acid, the reaction will proceed according to the equation, read from left to right ; but if we start with ethyl acetate and water it will proceed from right to left. In neither case, however, will it be complete. If one mol each of the reacting substances have been used, real equilibrium will have been established and the reaction will have ceased when the composition of the mixture has become: % mol acetic acid, % mol alcohol, % mol ethyl acetate and % mol water. This statement is not to be taken as meaning that when this relation is attained no further action occurs, but that the changes in one direction have become equal in unit time to those in the opposite direction ; the equilibrium being dynamic, not static. Chemical effects of light. Many chemical combinations and de- compositions are much modified by the intensity, and the kind of light to which the reacting substances are exposed. Hydrogen and chlorine gases do not combine, at the ordinary temperature, in the absence of light; in diffused daylight or gaslight, they unite slowly and quietly; in direct sunlight, or in the electric light, they unite suddenly and explosively. The salts of silver, used in photography, are not decomposed in the dark, but are rapidly decomposed in the presence of organic matter, when exposed to sunlight. Classification of the Elements. The elements were formerly divided into two great classes, metals and metalloids. The metals, being such substances as are opaque, possess what is known as metallic luster, are good conductors of heat and electricity, and are electropositive; the metalloids, on the other hand, such as are gaseous, or, if solid, do not possess metallic luster, have a compara- tively low power of conducting heat and electricity, and are electro- negative. This division, based upon purely 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. 52 TEXT-BOOK OF CHEMISTRY The classification of the elements should be such that each group shall contain elements whose chemical properties are similar the physical properties being considered only in so far as they are inti- mately connected with the chemical. 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 position of most of the more recently discovered elements is still uncertain, owing to the imperfect state of our knowledge of their properties. In this book the elements are classified according to resemblances in their chemical properties, based upon the nature of the oxides and the existence or non-existence of oxysalts: Class I. Typical Elements. Hydrogen. Oxygen. Although these two elements differ notably in their properties, they are here classed as typical elements, because together they form the basis of our classification ; they both play important parts in the formation of acids; neither would find a suitable place elsewhere in the classification ; and they may also be considered as typical from the point of view of ionization, as they form the characterizing ions of acids and bases, hydrion and hydroxidion. Class II. Elements which form no compounds. Helium, neon, argon, krypton, xenon, niton. Class III. Acidulous Elements. Elements whose oxides unite with water to form acids, never to form bases. Which do not form oxysalts. 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, columbium, tantalum. GROUP VII. Molybdenum, tungsten, osmium. Elements of this class are also called non-metah, in contradis- tinction to those of classes IV and V, which are collectively called metals. They are also referred tn as electronegative elements, because they are electronegative to hydrogen, although they are all CLASSIFICATION OF ELEMENTS 53 electropositive to oxygen, and individual members are also electro- positive to others of the class (p. 34). On electrolysis of compounds containing acidulous elements or oxygen, and metals or hydrogen, the former are usually found in the anion, the latter in the cation, as H 'K " I SO/'. But this is not invariably the case. Class IV. Amphoteric Elements. Elements whose oxides unite with water, some to form bases, others to form acids. Which form oxysalts. GROUP I. Gold. GROUP II. Chromium, manganese, iron. GROUP III. Uranium, radium, thorium. GROUP IV. Lead. GROUP V. Bismuth. GROUP VI. Titanium, germanium, zirconium, tin. GROUP VII. Palladium, platinum. GROUP VIII. Rhodium, ruthenium, iridium. The amphoteric and basylous elements are the metals or electro- positive elements, and have these properties in common: they form oxysalts, and are separated as cations on electrolysis of such salts. Class V. Basylous Elements. Elements whose oxides unite with water to form bases, never to form acids. Which form oxysalts. GROUP I. Lithium, sodium, potassium, rubidium, caesium, silver. GROUP II. Thallium. GROUP III. Calcium, strontium, barium. GROUP IV. Magnesium, zinc, cadmium. GROUP V. Glucinum, aluminium, scandium, gallium, indium. GROUP VI. Nickel, cobalt. GROUP VII. Copper, mercury. GROUP VIII. Yttrium, lanthanum, cerium, praseodymium, neody- mium, samarium, gadolinium, terbium, thulium, ytterbium. This class includes the more strongly electropositive metals. In classes III, IV and V the elements are subdivided into groups, the members of which have common distinctive characters, and are more or less closely allied to each other. In classes III and V the resemblances between individuals of groups occurring first in the list 54 TEXT-BOOK OF CHEMISTRY o OQ O 6 w JU 1 M 6 ^ j 3 ^ s - CO - S 2 05 to w " a PERIODIC LAW 55 are the most marked, and are more close than those between members of groups placed lower down. Periodic Law. If the elements are arranged in a continuous series in the numerical order of their atomic weights : H, He, Li, Gl, etc., it will be found that elements having similar properties, in them- selves and in their compounds, will fall in the same (vertical) line, or group. (See table on p. 54.) This connection between the periodicity of the atomic weights of the elements and their chemical relationships is expressed in the Periodic law of Mendelejeff. The properties of elements, the constitution of their compounds, and the properties of the latter are periodic functions of the atomic weights of the elements. But the law is not absolute, and, apart from the necessity of a few transpositions, the separation into dif- ferent groups of such closely related elements as Cu and Hg, Cr and Mn and Fe, and the grouping together of such dissimilar elements as Cu, Ag and Au are not in accordance with observed fact. It will be observed that the series is complete, with but a single break, between H=l and Tb=159, but that below that point the breaks are numerous. When the earlier tables were constructed (about 1870) the breaks were more numerous, but have been in part filled by the discovery of then unknown elements, such as scandium, gallium, germanium, and the entire argon group. It may, therefore, be expected that other breaks, still existing, may be filled by the dis- covery of other new elements of very high or very low atomic weights. INORGANIC 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 formation 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 weight 1 (International = 1.008) Molecular weight 2 Sp. gr. =0.06926 A One litre weighs 0.0899 gram 1 gram measures 11.16 litres. 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, acids, hydrogen sulphide, ammoniacal compounds, and in many organic substances. Preparation. (1) By electrolysis of acidulated water, H is given off at the negative pole. Utilized .when pure H is required. (2) By the dissociation of water at very high temperatures. (3) By the decomposition of water by certain metals. The alkali metals decompose water at the ordinary temperature: Na 2 + 2H 2 2NaOH -f H 2 Sodium. Water. Sodium hydroxide. Hydrogen. Some other metals, such as iron and copper, effect the decomposi- tion only at high temperatures: 3Fe 2 -f 8H 2 2Fe 3 4 -f 8H 2 Iron. Water. Triferric teroxide. Hydrogen. (4) By decomposition of mineral acids, in the presence of water, by zinc and certain other metals : Zn -f H 2 S0 4 + #H 2 = ZnS0 4 -f H 2 -f #H 2 O Zinc. Sulphuric acid. Water. Zinc sulphate. Hydrogen. Water. 5? 58 TEXT-BOOK OF CHEMISTRY Properties. Physical. Hydrogen is a colorless, odorless, taste- less gas; 14.47 times lighter than air, being the lightest substance known. The weight of a litre, 0.0896 gram, is called a crith. It is almost insoluble in water and alcohol. It conducts heat and elec- tricity better than any other gas. In obedience to Graham's 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. It is liquefied at 240 under a pressure of 13.3 atm. The liquid is clear and colorless, boils at 253, only 20 above the absolute zero, and has a sp. gr. of 0.068. Certain metals have the power of absorbing large quantities of hydrogen, which is then said to be occluded, and this action of the metal is called occlusion. Palladium absorbs 980 volumes of the gas when used as the negative electrode in the electrolysis of water. 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, and the fact that heat is liberated during the occlusion, would seem to indicate that the gas is contained in the metal, not in a mere physical state of con- densation, but in chemical combination. Chemical. Hydrogen exhibits no great tendency to combine with other elements at ordinary temperatures. It combines explosively, however, with chlorine under the influence of sunlight, and with fluorine even in the dark. 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 ex- plode 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. In a mixture of hydrogen and oxygen at the ordinary temperature formation of water takes place with extreme slowness. If a piece of platinum foil is introduced into the mixture combina- tion occurs with sensible rapidity, and, if the platinum is finely divided, the rapidity of the combination is such that the metal be- comes incandescent, and explodes the mixture. The platinum here is said to be a catalyser, i.e., a substance by whose presence the velocity of a reaction is accelerated. Catalysers are also called contact agents. Many compounds containing oxygen give up that element when heated in an atmosphere of hydrogen: CuO -f H a Cu -f H 2 Cupric oxide. Hydrogen. Copper. Water. The removal of oxygen from a compound is called a reduction or deoxidation. In a broader sense the term reduction is applied to OXYGEN 59 any diminution in the relative quantity of the electronegative factor in a compound. Thus mercuric chloride, HgCl 2 (Hg 200: Cl 71) Is reduced to mercurous chloride HgCl (Hg 200: Cl 35.5). At the instant that H is liberated from its compounds it has a deoxidizing power similar to that which ordinary H possesses only at elevated temperatures, and its tendency to combine with other elements is greater than under other conditions. 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, but at the instant of its liberation from a compound, it is in the form of individual atoms, and that portion of force required to split up the molecule into atoms, necessary when free H enters into reaction, is not required when the gas is in the nascent state. In its physical and chemical properties, hydrogen more closely resembles those usually ranked as metals than it does those forming the class of non-metals, among which it is usually placed. Its con- ducting power, as well as its relation to the acids, which may be considered as salts of H, tend to separate it from the non-metals. Analytical Characters. (1) Burns with a faintly blue flame, which deposits wrter on a cold surface brought over it; (2) Mixed with oxygen, explodes on contact with flame, producing water. OXYGEN. Oxygenium (U. S. P.) Symbol=0 Bivalent Atomic weight= 16; molecular w eight =32. Sp. #r.=1.10563 A (calculated=l.lOSS) ; 15.95 H. 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 ; it occurs in rocks and minerals (about 30 to 50 per cent, of the earth's crust), in water it is eight-ninths by weight. Preparation. (1) By heating certain oxides: 2HgO = 2Hg -f 2 Mercuric oxide. Mercury. Oxygen. 3MnO 2 Mn 3 O 4 -f O 2 Manganese dioxide. Trimanganic tetroxide. Oxygen. (2) By the electrolysis of water, acidulated with sulphuric acid, is given off at the positive pole. (3) By the action of sulphuric acid upon certain compounds rich in : manganese dioxide, potassium dichromate, and plumbic peroxide : 2MnO 2 -f 2H 2 SO 4 = 2MnSO 4 -f 2H 2 O -f O 2 Manganese dioxide. Sulphuric acid. Manganous sulphate. Water. Oxygen. 60 TEXT-BOOK OF CHEMISTRY (4) The best method, and that usually adopted, is by heating a mixture of potassium chlorate and manganese dioxide in equal parts. The chlorate gives up all its 0, according to the equation : 2KC10 3 = 2KC1 + 30, Potassium chlorate. Potassium chloride. Oxygen. A small quantity of free chlorine usually exists in the gas pro- duced by this reaction. If the oxygen is to be used for inhalation, the chlorine should be removed by allowing the gas to stand over water for 24 hours. (5) By the decomposition by heat of certain salts rich in 0: alkaline permanganates, nitrates and chlorates. (6) By the action of water upon sodium peroxide: 2Na 2 2 + 2H 2 = 4NaOH + 2 Sodium peroxide. Water. Sodium hydroxide. Oxygen Oxygen is official in the U. S. P. as Oxygenium; it contains not less than 95 per cent, by volume of 0, and for convenience it is usually compressed in metal cylinders. Properties. Physical. Oxygen is a colorless, odorless, tasteless gas, soluble in water in the proportion of 7.08 cc. in 1 litre of water at 14.8, somewhat more soluble in absolute alcohol. It liquefies at 140 under a pressure of 300 atmospheres. Liquid oxygen boils at 187.4 at the ordinary pressure. Chemical. Oxygen is characterized, chemically, by the strong tendency which it exhibits to enter into combination with other ele- ments. It forms binary compounds with all elements except fluorine and bromine. With most elements it unites directly, especially at elevated temperatures. In many instances this union is attended by the appearance of light, and always by the extrication of heat. The luminous union of with another element constitutes the familiar phenomenon of combustion, and is the principal source from which we obtain so-called artificial heat 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 combustible substances will unite with them, or with some of their constituents, the union being attended with the appearance of heat and light. The distinc- tion between combustible substances and supporters of combustion 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. An oxidation is a chemical action in which oxygen combines with an element or a compound. The burning of coal: C-|-0=CO or C-}-0 2 =:C0 2 ; and the formation of acetic acid from alcohol: OZONE 61 C 2 H 6 +0 2 =C 2 H 4 2 -f H 2 0, are oxidations. In a broader sense the word " oxidation" is sometimes used as the opposite to "reduction" (p. 58) to apply to any increase in the relative quantity of the electro- negative element in a compound. Thus the conversion of FeCl 2 (Fe 56:C1 71) into FeCl 3 (Fe 56:C1 106.5) may be referred to as an oxidation, although it is, more properly, a chlorination. 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, S0 3 , unites with water to form sulphuric acid, H 2 S0 4 . 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 C 4 H G 3 is known as acetic anhydride, because it combines with water to form acetic acid : C 4 H 6 3 +H 2 0=2C 2 H 4 2 . (See compounds of arsenic and sulphur.) 2. Basic oxides are such as combine with water to form bases. Thus calcium oxide, CaO, unites with water to form calcium hydrox- ide, CaH 2 2 . 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 hydrogen monoxide, or water. In other cases they are formed by the union of two other oxides, one basic, the other acid in quality, such as the red oxide of lead, Pb 3 4 , formed by the union of a molecule of the acidulous peroxide, Pb0 2 , 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 0, when mixed with nitrogen dioxide, produces a brown gas. OZONE. Allotropic oxygen (see Allotropy, p. 9). Formula=Q 3 . Mo- lecular weight 48. Air through which discharges of static electricity have been passed, and oxygen obtained by the decomposition of water (if electrodes of gold or platinum be used), have a peculiar odor, somewhat resembling that of sulphur, which is due to the conversion of a part of the oxygen into ozone. Preparation. (1) By the decomposition 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 : 62 TEXT-BOOK OF CHEMISTRY 3Ba0 2 +3H 2 S0 4 =3BaS0 4 +3H 2 0+0 3 (4) By the passage of silent electric discharges through air or oxygen. Properties. When pure, it is a dark liquid, almost opaque in lay- ers 2 mm. thick, which is not decomposed at the ordinary temperature, but converted into a bluish gas. It'boils at 119. 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 chemical activity of ozone, haye led chemists to regard it as condensed oxygen; the molecule of ozone being represented thus (000), while that of ordinary oxygen is (00): 30 2 =20 3 . Ozone is very sparingly soluble in water, more soluble in the presence of hypophosphites, insoluble in solutions of acids and alkalies. In the presence of moisture it is slowly converted into oxygen at 100, a change which takes place rapidly and completely at 237 . It is a powerful oxidant ; it decomposes solutions of potas- sium iodide with formation of potassium hydroxide, and liberation of iodine; it oxidizes all metals except gold and platinum, in the presence of moisture; it decolorizes indigo and other organic pig- ments, and acts rapidly upon rubber, cork, and other organic substances. Analytical Characters. (1) Neutral litmus paper, impregnated with solution of potassium iodide, is turned blue when exposed to air containing 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. (4) Paper impregnated with fresh tincture of natural (unpurified) guaiacum is colored blue by ozone. (5) Metallic silver is blackened by ozone. When inhaled, air containing 0.07 gram of ozone per litre causes intense coryza and hemoptysis. 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 monoxide or water, H 2 0; hydrogen dioxide or oxygenated water, H 2 2 . WATER. H 2 Molecular weight IS Sp. gr.\ Vapor density =0.6218 A ; calculated=Q.62M. Occurrence. In unorganized nature H 2 exists in the gaseous WATER 63 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 proportions in cer- tain crystals, to the maintenance of whose shape it is necessary. In the organized world H 2 forms a constituent part of every tissue and fluid. Formation. Water is formed: (1) By union, brought about by elevation of temperature, of one vol. with two vols. H. (2) By burning H, or substances containing it, in air or in 0. (3) By heating organic substances containing H to redness with cupric oxide, or with other substances capable of yielding 0. This method of formation is utilized to determine the amount of H con- tained in organic substances. (4) When an acid and a hydroxide react upon each other to form a salt : H 2 S0 4 -f- 2KOH = K 2 S0 4 -f- 2H 2 O Sulphuric acid. Potassium hydroxide. Potassium sulphate. Water. (5) When a metallic oxide is reduced by hydrogen: CuO + H 2 = Cu -f H 2 O Cupric oxide. Hydrogen. Copper. Water. (6) In the reduction and oxidation of many organic substances. Pure H 2 is not found in nature. When required free from ordi- nary impurities it is separated from suspended matters by filtration, and from dissolved substances by distillation. Properties. Physical. With a barometric pressure of 760 mm. H 2 O is solid below 0; liquid between and 100; and gaseous above 100. Water is the best solvent we have, and acts in some instances as a simple solvent, in others as a chemical solvent. Vapor of water is colorless, transparent, and invisible. The latent heat of vaporization of water is 536.5 ; that is, as much heat is required to vaporize 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. and 2 vols. H, or 8 by weight of and 1 by weight of H, either by analysis or synthesis. Analysis is the reducing of a compound to its constituent parts or 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: (1) By elec- 64 TEXT-BOOK OP CHEMISTRY trolysis of acidulated water; H being given off at the negative and at the positive pole. (2) By passing vapor of H 2 through a platinum tube heated to whiteness, or through a porcelain tube heated to about 1,100. The decomposition of a compound gas or vapor by elevation of tem- perature is called dissociation. (3) By the action of the alkali metals. Hydrogen is given off, and the metallic hydroxide remains in solution in an excess of H 2 0. (4) By passing vapor of H 2 over red-hot iron. Oxide of iron remains and H is given off. Water combines with oxides to form new compounds, some of which are acids and others bases, known as hydroxides. A hydroxide is a compound formed by the replacement of half of the hydrogen of water by another element or by a radical. A hydrate is a compound containing chemically combined water. The act of union of a substance with water is referred to as hydration. The hydroxides of the electro-negative elements and radicals are acids; most of those of the electro-positive elements and radicals are basic hydroxides. Certain substances, in crystallizing, combine with a definite pro- portion 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 chemical reactions. In many instances a portion of the water of crystallization may be driven off at a comparatively low temperature, while a higher temperature is required to expel the remainder. This latter is known as water of constitution. The symbol Aq (Latin, aqua) is frequently used to designate the water of crystallization, the water of constitution being indicated by H 2 0. Thus MgS0 4 , H 2 0+6Aq represents magnesium sulphate with one molecule of water of constitution and six molecules of water of crystallization. We consider it preferable, however, as the distinc- tion between water of crystallization and water of constitution in many salts is only one of degree and not of kind, to use the symbol Aq to designate the sum of the two ; thus, MgS0 4 +7Aq. Water decomposes the chlorides of the third class (see p. 52) of elements (those of carbon only at high temperatures and under pressure). Thus phosphorous trichloride forms phosphorous nnd hydrochloric acids: PC1 3 +3H 2 0:=H 3 PO.,+3HC1. A decomposition attended with absorption of water is called hydrolysis. Natural Waters. Natural waters which appear to the senses to be fit for drinking are called potable waters, in contradistinction to such as are, from their taste and appearance, obviously unfit for that use. Potable waters may be classified, according to their origin, into four groups: (1) Meteoric waters: rain water and melted snow. These are the purest WATER 65 natural wafers if uncontaminated ; they contain very small quantities of solids, and are^ highly aerated. Rain water falling during the first part of a shower is less "pure than that which falls subsequently. In districts where notable quantities of coal which contain sulphur are burnt, rain water contains more sulphates, ammoniacal salts, nitrates and nitrites than elsewhere. (2) Surface waters: the waters of rivers, lakes and ponds. These are mix- tures, in varying proportions, of rain water, spring water and the drainage of the surrounding land. They vary greatly in natural purity, and are frequently contaminated by sewage and other refuse. (3) Ground waters: water which permeates the superficial stratum above the uppermost impermeable rock. This is the water obtained in surface wells and in driven wells. Its quality depends upon what is in and on the stratum in which the well is dug; a driven well in a sandy stratum remote from habi- tations yields an excellent water, while the water of a well near a privy vault or a defective sewer is more or less diluted sewage. In limestone districts ground water is hard. (4) Deep waters: spring waters and those of artesian wells. Spring water is rain water which, having percolated through a portion 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 percolated, the dura- tion of contact, and the pressure to which it was subject during such contact. Spring waters from igneous rocks and from the older sedimentary forma- tions are fresh and sweet, and any spring water may be considered such whose temperature is less than 20, and which does not contain more than 40 parts in 100,000 of solid matter; provided 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 dis- trict, until a pervious layer, between two impervious strata, is reached; the outcrop of the system being in an adjacent elevated regiom Properties of Potable Waters. A water to be fit for drinking purposes 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. But, while 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 possess them as beyond suspicion. Impurities. The most dangerous of all contaminations of drinking waters is by admixture of sewage, which may be present in a water in quantity sufficient to render it unfit for use and the water yet retain all of the characters of a good water above referred to. To determine whether a water is really fit for drinking a chemical analysis and a bacteriological examination are necessary. For both of these methods the student is referred to treatises on that subject. The constituents usually determined, and the interpretation of the results, are as follows: Total Solids. The amount of solid material dissolved in potable waters varies from 4.3 to 50 in 100,000 (2.5 to 29.2 grains per U. S. gal.); and a water containing more than the latter quantity is to be condemned on that account alone. Chlorides. The presence of the chlorides of the alkaline metals, in quan- tities not sufficient to be detectable by the taste, is of no importance per se; but in connection with the presence of organic impurity, a determination 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 com- pounds, the presence of a large amount of chlorine serves to indicate that 66 TEXTBOOK OF CHEMISTRY 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 1.7 in 100,000 (1 grain per U. S. gal.) of that element. Hardness. The greater part of the solid matter dissolved in natural fresh waters consists of the salts of calcium, accompanied by less quantities of the salts of magnesium. The calcium salt is usually the bicarbonate 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 is due to the presence of the bicarbonate it is temporary, if due to the sulphate it is permanent. Cal- cium 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. As calcium sul- phate is held in solution by virtue of its own, albeit sparing, solubility, it is not deposited when the water is boiled; the addition of sodium carbonate per- manently softens hard water: CaS0 4 -f-Na 2 C0 3 =CaC0 3 -}-Na 2 SO 4 . Rain water is the softest water. The hardness is now usually reported in terms of calcium carbonate, CaC0 3 , either in grains per gallon or parts in 100,000. It is also sometimes reported in "degrees," which represent grains of CaCO 3 per imperial gallon. Very soft waters contain about 5CaCO 3 in 100,000, and hard waters 15 or over. Usually a water containing more than 20CaCO 3 in 100,000 is considered too hard for domestic use, unless softened by boiling. But a water is not to be condemned solely because its hardness exceeds this limit, because in certain limestone dis- tricts all waters are very hard. Waters which owe their hardness to excess of magnesium salts, cause in- testinal disturbances in those not habituated to them. Organic Matter. Technically, organic impurities in a water consist of vegetable or animal matters containing nitrogen. We have seen that the quan- tity of chlorine affords an indication as to whether the organic impurity found to be present is of vegetable or of animal origin. Animal organic contamina- tion has its origin in sewage, and its presence consequently indicates that the water is, or may at any moment become, the means of transmitting water- borne diseases, such as typhoid and cholera. The nitrogenous substances in feces and urine consist of albuminous bodies, crystalline organic compounds (such as urea, leucin, etc.) and ammoniacal salts. By the action of micro-organisms, which exist in the soil and in water, the albuminous and crystalline compounds are gradually converted into ammonium compounds, which are subsequently oxidized by atmospheric or dissolved oxygen, aided by bacterial influence, to nitrites and later to nitrates. Consequently the amount of sewage contamination, and the degree in which such contamination has been subsequently modified, can be inferred from quantitative determinations of the nitrogen present in the several forms referred to. In the usual process of water analysis the following factors are determined quantitatively : A. Albuminoid ammonia, which represents the nitrogen present in albumi- nous and crystalline combination. B. Free ammonia, which represents the ammoniacal compounds. C. Nitrogen in nitrates and nitrites. D. Nitrites. If a water yields 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 (.002 to .005 in 100,000) it is still quite pure. When the WATER 67 albuminoid ammonia reaches 0.1 milligr. per litre (.01 in 100,000) the water is to be looked upon with suspicion ; and it is to be condemned when the proportion reaches 0.15 (.015 in 100,000). When free ammonia is also present in considerable quantity, a water yielding 0.05 (.005 in 100,000) of albuminoid ammonia is to be looked upon with suspicion. Nitrates and nitrites are present in rain water in quantities less than 0.5 in 100,000, calculated as nitrogen. When the amount exceeds this, these salts are considered as indicating previous contamination by organic matter which has been oxidized and whose nitrogen has been to some extent converted into nitrites and nitrates. The quantity of nitrites in good waters does not exceed .002 in 100,000 when they are present. A larger quantity is considered as indicating previous organic contamination. Poisonous Metals. Natural waters containing notable quantities of iron compounds belong to the class of chalybeate mineral waters. Contact with metallic iron does not contaminate water. In districts where copper deposits exist the waters sometimes contain copper, and the waters of some streams contain arsenic. Lead in drinking water has been a prolific source of chronic lead poisoning. As lead is only dissolved by water after oxidation, conditions favoring oxidation of the metal favor its solution. Such conditions are: the presence of nitrates, a highly aerated condition of the water, alternate wetting and drying of the surface of the metal, the absence of sulphates and carbonates, and the presence of much carbonic acid dissolved under pressure (soda water). Sulphates and carbonates prevent solution by the formation of a protecting coating of an insoluble salt. 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 occurs when the water is at a high temperature, or when it lasts for a long period. Purification of Water. The artificial means of rendering a more or less contaminated water fit for use are of five kinds: Distillation, subsidence, filtra- tion, precipitation, and boiling. Distillation is resorted to in the laboratory to obtain very pure water, also, on a larger scale, to purify drinking water. When water is diitilled, the first portion should not be used, because it contains the gaseous impurities; and the last part should not be used, because it contains the solid impurities. Distilled water is official in the U. S. P. as Aqua destillata. When distilled water is to be used for drinking it should be aerated and charged with salts to the extent of about 0.03 gram each of calcium bicarbonate and sodium chloride to the litre. In filtration suspended impurities are removed more or less completely by passing the water through a porous material. In filter beds, used to filter large quantities of water, sand is the filtering material used, either alone or combined with charcoal or spongy iron. In domestic filters, treating small quantities of water, the filtering material is quartz sand, charcoal, porous stone, or unglazed earthenware or porcelain. Whatever may be the size or construction of the filter, it must be cleaned periodically. If this is neglected the filter ceases to purify the water, and becomes itself a source of contamination. Dis- solved organic matter is in part removed by oxidation in filtration through sand filter beds several feet in thickness, or through much thinner layers of charcoal or porous iron. Typhoid and cholera germs pass, although in greatly diminished numbers, through all filters except those made of unglazed porcelain. Precipitation methods were formerly used only to soften temporarily hard waters. One method consists in the addition of lime water in quantity just sufficient to convert the soluble calcium bicarbonate present into the insoluble carbonate. At present precipitation methods are also used, in combination with 68 TEXT BOOK OF CHEMISTRY subsidence and filtration, to remove organic impurities; alum or a ferric salt is added, an excess being avoided, to form a gelatinous precipitate which carries the impurities down with it mechanically as it settles when the water is left at rest in the subsidence tanks; the water in drawn oil from above the deposit to the filters, after a proper interval. Precipitation and subsidence are thus used to diminish the work required of the filters. The purification of water by boiling can only be carried on on a small scale. It is very useful, however, to soften temporarily hard waters and, par- ticularly, to sterilize infected waters. For the latter purpose the boiling must be continued actively for at least twenty minutes in a vessel closed except for a steam outlet, which is to be stopped with a plug of cotton when the vessel is taken off to cool. Natural Purification of Water. The water of brooks, rivers, and* lakes which have been contaminated by sewage and other organic impurity becomes gradually purified by natural processes. Suspended particles are deposited upon the bottom and sides of the stream, more or less rapidly, according to their gravity and the rapidity of the current. The bicarbonates of calcium, magnesium, and iron gradually lose carbon dioxide, and are precipitated as car- bonates, which mechanically carry down dissolved as well as suspended im- purities. The decompositions, oxidations, and reductions to whicli organic mat- ters are subject under the influence of atmospheric and dissolved oxygen and bacterial action bring about their gradual mineralization by conversion into ammonia and then into nitrates. The processes of nutrition of aquatic plant life absorb dissolved organic impurity, as well as the products of decomposition of nitrogenized substances. This natural purification proceeds the more rapidly the more contact with air is favored. 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. A useful classification which has been generally adopted includes five classes : I. Acidulous icatcrs; whose value depends upon dissolved carbonic acid. They contain but small quantities of solids, principally the bicarbonates of sodium and calcium and sodium chloride. II. Alkaline waters; which contain quantities of the 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 proportion than 4 parts in 100,000. They contain ferrous bicarbonate and sulphate, calcium carbonate, sulphates of potassium, sodium, calcium, magnesium, and aluminium, notable quantities of sodium chloride, and frequently small amounts of arsenic. 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 icatcrs ; which contain neutral salts in considerable quantity. The nature of the salts which they contain is so diverse that the group may well be subdivided: (a) Chlorine waters; which contain large quantities of sodium chloride, accompanied by less amounts of the chlorides of potassium, calcium, and mag- nesium. 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 300 parts in 100,000 of sodium chloride belongs to this class, provided it does not contain substances more active in their medicinal action in such proportion as to warrant its classification elsewhere. HYDROGEN DIOXIDE 69 Waters containing more than 1,500 parts in 100,000 are too concentrated for internal administration. (&) ~ Sulphate ivaters are actively purgative from the 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 sulphates of magnesium and calcium is as high as 3,000 parts in 100,000 to 2,000 parts in 100,000 of sodium sulphate. They vary much in concentration; from 500 to nearly 6,000 parts of total solids in 100,000. They have a salty, bitter taste, and vary much in temperature. (c) Bromine and Iodine waters are such as contain the bromides or iodides of potassium, sodium, or magnesium in sufficient quantity to communicate to them the medicinal properties of those salts. V. Sulphurous waters; which hold hydrogen sulphide or metallic sulphides in solution. They have a disagreeable odor and are usually warm. They contain 20 to 400 parts in 100,000 of total solids. 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 (2Vs to 3 quarts) a day. The greater the elimination and the drier the nature of the food the greater is the amount of H 2 taken in the liquid form. Water is a constituent of every tissue and fluid of the body, vary- ing from 0.2 per cent, in the enamel of the teeth to 99.5 per cent, in the perspiration 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 H L ,0, but is influenced by the nature of the solids. The blood, although liquid in the ordinary sense of the term, contains a less proportional amount of H 2 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 2 to solids than does that liquid. Water is discharged by the kidneys, intestines, skin, and pulmo- nary 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 2 2 Molecular weight=34Sp. #r.=1.455. Occurence. Exists naturally in very minute quantity in rain- water, in air, and in the saliva. Preparation. (1) It may be obtained, mixed with a large quan- tity of H 2 0, by the action of dilute mineral acids on barium dioxide : Ba0 2 +H 2 S0 4 =:BaS0 4 +H 2 2 70 TEXT-BOOK OF CHEMISTRY (2) 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. (3) It is prepared industrially of 10-12 volume strength by gradually adding barium dioxide to dilute hydrofluoric acid solution, the mixture being maintained at a low temperature and constantly agitated. (4) In still greater concentration by the action of dilute acids on sodium dioxide, care being had to prevent heating of the mixture : Na 2 O 2 +2HCl=2NaCl+H 2 2 (5) Hydrogen dioxide is also formed when sodium dioxide is dis- solved in water : Na 2 2 +2H 2 0=2NaOH+H 2 2 Properties. The pure substance is a colorless, syrupy liquid, which, when poured into H 2 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. It is very unstable, and, even in darkness and at ordinary temperature, is gradually de- composed. At 20 the decomposition takes place more quickly and at 100 rapidly and with effervescence. The dilute substance, how- ever, is comparatively stable, and may be boiled and even distilled without suffering decomposition. Yet it is liable to explosive de- composition when exposed to summer temperature in closed vessels. Hydrogen dioxide 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 ele- mentary silver remaining. By certain substances, such as gold, platinum, and charcoal in a state o- fine division, fibrin, or manga- nese dioxide, it is decomposed with evolution of oxygen; the decom- posing 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 reno- vation of old oil-paintings. It is an energetic disinfectant and anti- septic, and is used in surgery. "Ozonic ether" is a mixture of ethylic ether and dilute hydrogen dioxide. Solution of Hydrogen Dioxide Liquor Hydrogenii Dioxidi (U. S. P.) is an aqueous solution containing not less than 3 per cent, by weight of H,0 2 , and corresponding to not less than 10 vol- umes of available oxygen. Analytical Characters. (1) To a solution of starch a few drops of cadmium iodide solution are added, then a small quantity of Ili<> HYDROGEN DIOXIDE 71 fluid to be tested, and, finally, a drop of a solution of ferrous sul- phate. A blue color is produced in the presence of hydrogen dioxide even if the solution 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. (3) Add to the liquid a few drops of potassium dichromate and a little dilute sulphuric acid, and agitate with ether. The ether assumes a brilliant blue-violet color. CLASS II. ELEMENTS WHICH FORM NO COMPOUNDS. HELIUM. NEON. ARGON. KRYPTON. XENON. NITON. The elements of this group have been recently discovered, and exist in air and in certain minerals. As they form no compounds, their atomic weights are not known, although, from their molecular heats, there is reason to believe that their molecular symbols are He, etc., not He 2 , etc. Argon, the most abundant of the class, was discovered by Ray- leigh and Ramsay in 1894 in air, in which it exists in the propor- tion of 0.9 in 100 by volume, and 1.2 per cent, by weight. It is a transparent, colorless, odorless, tasteless gas; sp. gr.=19.941; Mw.= 40 (International=39.88). At the normal pressure it liquefies at 186.9, forming a colorless liquid of sp. gr. 1.5. It solidifies at 190. It is sparingly soluble in water: 4.05 in 100. It is obtained from atmospheric air as a residue by causing the other constituents to enter into combination. When rarefied it gives a characteristic spectrum of many lines with the induction spark. Helium owes its name to the fact that its existence in the sun's atmosphere was recognized by the characteristic line D 3 of the solar spectrum before it was discovered as a terrestrial element. It exists in certain rare uranium minerals, and in some spring waters. It is a very light gas: Mw.=4. The other members of the class: Neon: Mw.=20 ( International = 20.2) ; Krypton: Mw.=83 (International=82.92) ; and Xenon: Mw. =130 (International=130.2), have been found in small amount in the residue of evaporation of liquefied air. Niton: Mw.=222 (International=222.4), radium emanation, also belongs to this group. It has been estimated that these gases are present in air, in about the following proportions : Argon 0.9 part in 100 of air. Neon 1 to 2 parts in 100,000 of air. Krypton 1 part in 1,000,000 of air. Helium 1 to 2 parts in 1,000,000 of air. Xenon 1 part in 20,000,000 of air. 72 CLASS III. ACIDULOUS ELEMENTS. Elements all of whose Hydrates are Acids and which do not form Salts with the Oxyacids. I. CHLORINE GROUP. FLUORINE. CHLORINE. BROMINE. IODINE. The elements of this group, known as the halogens, closely resemble each other in their chemical properties and in the structure and properties of their compounds, fluorine differing more from the other three than these do from each other. They are univalent in the great majority of the compounds into whose formation they enter, although they are sometimes trivalent, as in IC1 3 . With hydrogen each forms an acid compound, composed of one volume of the halogen in the gaseous state with one volume of hydrogen. All mineral acids into whose composition they enter are monobasic. Fluorine is a gas, liquefiable. with difficulty, chlorine an easily liquefiable gas, bromine a liquid, and iodine a solid at the ordinary temperature and pressure. The relations of their compounds to each other are shown in the following table : J1X 1 HC1 HBr HI Hydro-ic C1 2 O CIA HC1O HBrO HIO Hypo- HC10 2 HC10 3 HBr0 8 HI0 3 -ic acid. HC10 4 HBr0 4 HIO 4 Per-ic I 2 4 Tetroxide. HI0 2 -ous acid. Monoxide. acid. ous acid. acid. FLUORINE. =F Atomic weight 19 (International=19.Q). Molecu- lar weigJit3S.Sp. gr. 1.265 A (calculated 1.316) . Fluorine has been isolated by the electrolysis of pure, dry HF at 23 . It exists in nature chiefly in Fluor-Spar, CaF 2 , and in cryolite, A1 2 F 6 (NaF) G . It is a gas, colorless in thin layers, greenish yellow in thick layers. It decomposes H 2 0, with formation of HF and ozone. In it Si, B, As, Sb, S, and I fire spontaneously. With H it detonates, even in the dark. It attacks organic substances violently. The apparatus in which it is liberated must be made of platinum or fluor-spar. It forms compounds with all other elements except oxygen. Hydrogen Fluoride. Hydrofluoric acid=H~F Molecular weight =20. Hydrofluoric acid is obtained by the action of an excess of 73 74 TEXT-BOOK OF CHEMISTRY sulphuric acid upon fluor-spar or upon barium fluoride, with the aid of gentle heat: CaF 2 +H 2 S0 4 =CaS0 4 +2HF. If a solution is 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 pure acid is a colorless liquid, which boils at 19 and solidifies at 1. Sp. gr. 0.985 at 12. 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 comes in contact with the skin, as they produce painful ulcers which heal with difficulty, and also constitutional symptoms which may last for days. The inhalation of air containing very small quantities of HF has caused permanent loss of voice, and in rare cases, death. When the acid has accidentally come in contact with the skin the part should be washed with dilute solution of potassium hydroxide, and the vesicle which forms should be opened. 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. Dur- ing the process of etching the HF attacks the silica and forms a gaseous silicon fluoride: Si0 2 -f4HF=SiF 4 +2H 2 Test. The presence of fluorine in a compound is detected by re- ducing the substance to powder, moistening it with sulphuric acid in a platinum crucible, 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 (International=35A6) Mo- lecular weight=7lSp. 0r.=2.4502 A. Occurrence. Only in combination, most abundantly in sodium chloride ; the chlorides of potassium, calcium, and magnesium are also frequently found in nature. Preparation. (1) By heating together manganese dioxide and hydrochloric acid: Mn0 2 +4HCl=MnCl 2 +2H 2 0+Cl 2 In a modification of this process, which permits of the more easy recovery of the manganese dioxide, nitric acid is used along with hydrochloric. The reaction is: CHLORINE 75 '2HCl+2HN0 3 +Mn0 2 =Mn(N0 3 ) 2 +2H 2 04-Cl 2 The MnO 2 and HN0 3 are recovered by heating the manganese nitrate to 190 and treating the vapor with air and steam. The reactions are : Mn(N0 3 ) 2 =Mn0 2 +N 2 4 and N 2 4 -[-H 2 0+0=2HN0 3 (2) By the action of manganese dioxide upon hydrochloric acid in the presence of sulphuric acid, manganous sulphate being also formed : Mn0 2 +2HCl+H 2 S0 4 =MnS0 4 +2H 2 0+Cl 2 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. Hydro- chloric acid and sodium sulphate are first formed: H 2 S0 4 +2NaCl=:Na 2 S0 4 +2HCl ; and the acid is immediately decomposed by either of the reactions indicated in (1) and (2), according as sulphuric acid is or is not present in excess. (4) By the action of potassium dichromate upon hydrochloric acid; potassium and chromic chlorides being also formed: K 2 Cr 2 7 +14HCl=2KCl+2CrCl 3 +7H 2 0+3Cl 2 (5) In Deacon's process cupric oxide is used as a "contact sub- stance" to oxidize hydrochloric acid. The reactions are: 2CuCl 2 =2CuCl+Cl 2 , then, 2CuCl+0 2 =2CuO+Clo, and, finally, 2CuO+4HCl=2CuCl 2 +2H 2 As the is derived from air the Cl obtained is largely diluted with N. Properties. Physical. It is about 2 1 / times heavier than air; it is a greenish yellow gas, at the ordinary temperature and pressure; it has a penetrating odor, and is, even when highly diluted, very irritating to the respiratory passages. Being soluble in H 2 to the extent of one volume to three volumes of the solvent, it must be collected by displacement of air. An aqueous solution containing, when freshly made, a mixture of chlorine and oxides of chlorine, equivalent to about 0.35 gm. of available chlorine in each 100 cc. of the solution is known as chlorine water, and is official in the U. S. P. as Liquor chlori compositus. It should bleach, but not redden, litmus paper. Under a pressure of 6 atmospheres at 0, or S l /2 atmospheres at 12, Cl becomes an oily, yellow liquid, of sp. gr. 1.33; and boiling at 33.6. Liquid chlorine, transported in lead-lined steel cylinders, is now an article of commerce. 76 TEXT-BOOK OF CHEMISTRY Chemical. Chlorine exhibits a great tendency to combine with other elements, with all of which, except F, 0, N, and C, it unites directly, frequently with evolution of light as well as heat, and sometimes with an explosion. With H it combines slowly, to form hydrochloric acid, under the influence of diffuse daylight, and vio- lently in direct sunlight, or in highly actinic artificial lights. A candle burns in Cl with a faint flame and thick smoke, its H com- bining with the Cl, while carbon becomes free. At a red heat Cl decomposes H 2 rapidly, with formation of hydrochloric, chloric, and probably hypochlorous acids. 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 In the presence of H,0, chlorine is an active bleaching and dis- infecting agent. It acts as an indirect oxidant, decomposing H 2 0, the nascent from which then attacks the coloring or odorous principle : H 2 0+C1 2 =2HC1+0 Chlorine is readily fixed by many organic substances, either by addition or substitution. In the first instance, as when Cl and olefiant gas unite to form ethylene chloride, the organic substance simply takes up two or more atoms of chlorine: C 2 H 4 -|-C1 2 =C 2 H 4 C1 2 . In the second instance, as when Cl acts upon marsh gas to produce methyl chloride: CH 4 -(-Cl2=CH 3 Cl-(-HCl, each substituted atom of Cl displaces an atom of H, which combines with another Cl atom to form hydrochloric acid. Hydrogen Chloride Hydrochloric Acid Muriatic Acid Acidum Hydrochloricum (U. S. P.) HC1 Molecular weight= 36.5 Sp. gr. 1.259 A. Occurrence. In volcanic gases and in the gastric juice of the mammalia. 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 2 S0 4 +2NaCl=Na 2 S0 4 +2HCl This is the reaction by which HC1 used in the arts is produced. (3) Hydrochloric acid is also formed in a great number of re- actions, as when Cl is substituted in an organic compound. Properties. Physical. A colorless gas, acid in reaction and taste, having a sharp, penetrating odor, and producing great irritation when inhaled. It becomes liquid under a pressure of 40 atmospheres at 4. Its critical temperature is 52 and its critical pressure 83 atmospheres. It is very soluble in H 2 0, one volume of which dissolves 480 volumes of the gas at 0. Chemical Hydrochloric acid is neither combustible nor a sup- CHLORINE 77 porter of combustion, although certain elements, such as K 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 phar- macy. 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 concentration. When heated, it evolves HC1, if it contain more than 20 per cent, of that gas, and H 2 if it con- tain less. A solution containing 20 per cent, boils at 111, is of sp. gr. 1.099, has the composition HC1+8H 2 0, and distils unchanged. Commercial muriatic acid is a yellow liquid ; sp. gr. about 1.16 ; contains 32 per cent. HC1 ; and contains ferric chloride, sodium chloride, and arsenical compounds. Acidum hydrochloricum is a colorless liquid, containing small quantities of impurities. It contains not less than 31 per cent, nor more than 33 per cent. HC1 and its sp. gr. is about 1.155 at 25 C. (U. S. P.) The dilute acid is the above diluted with water. Sp. gr. 1.049=not less than 9.5 per cent, nor more than 10.5 per cent. HC1 (U. S. P.). C. P. (chemically pure} acid is usually the same as the strong pharmaceutical acid and far from pure (see below). The strongest solution has a sp. gr. of 1.20 and contains 40.8 per cent. HC1. Hydrochloric acid is classed, along with nitric and sulphuric acids, as one >of three strong mineral acids. It is decomposed by many elements, with formation of a chloride and liberation of hydrogen: 2HCl+Zn=ZnCl 2 +H 2 With oxides and hydroxides of the metals it enters into double decomposition, forming H 2 and a chloride: CaO+2HCl=CaCl 2 +H 2 or Ca(OH) 2 +2HCl=CaCl 2 +2H 2 Oxidizing agents decompose HC1 with liberation of Cl. A mix- ture of hydrochloric and nitric acids in the proportion of three molecules of the former to one of the latter (18 cc. HN0 3 : 82 cc. HC1 soln.), is the acidum nitrohydrochloricum (nitrohydrochloric acid, nitromuriatic acid) of the U. S. P., or aqua regia (see p. 102). The latter name alludes to its power of dissolving gold, by combina- tion of the nascent Cl, which it liberates, with that metal, to form the soluble auric chloride (p. 129). The U. S. P. also includes acidum nitrohydrochloricum dilutum (diluted nitrohydrochloric acid, diluted nitromuriatic acid), which contains 10 cc. HN0 3 ; 45.5 cc. HC1; and 194.5 cc. H 2 0. 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 78 TEXT-BOOK OF CHEMISTRY formed with barium chloride; Chlorine colors the acid yellow; Lead gives a black color when the acid is treated with hydrogen sulphide; Iron the acid gives a red color with ammonium thiotyanate; 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 H 2 O, and to which a small quantity of potassium chlorate has been added, is evaporated over the water bath to 400 cc. ; 25 cc. of sulphuric acid are then added, and the evaporation continued until the liquid measures about 100 cc. This is introduced into a Marsh appara- tus and must produce no mirror during an hour. Chlorides. A few of the chlorides are liquid, SnCl 4 , SbCl 5 ; the remainder are solid, crystalline and more or less volatile. The me- tallic chlorides are soluble in water, except AgCl and HgCl, which are insoluble, and PbCl 2 , and CuCl, which are sparingly soluble. The chlorides of the non-metals are decomposed by H 2 0. The chlorides are formed: (1) By direct union of the elements: P+C1 5 =PC1 5 ; (2) By the action of chlorine upon a heated mixture of oxide and carbon: A1 2 3 +3C+3C1 2 =A1 2 C1 6 +3CO ; (3) By solution of the metal, oxide, hydroxide, or carbonate in HC1: Zn+2HCl=ZnCl 2 +H 2 (4) By double decomposition between a solution of a chloride and that of another salt whose metal forms an insoluble chloride: AgN0 3 +NaCl=AgCl+NaN0 3 Chloridion Analytical Characters. Solutions of hydrochloric acid and of chlorides contain the ion, chloridion CT, which gives the following reactions: (1) With AgNO 3 a white, flocculent ppt., insol. in HN0 3 , sol. in NH 4 OH. (2) With HgNO 3 , a white ppt., which turns black with NH 4 OH. Toxicology. Poisons and Corrosives A poison is any substance which, being in solution in, or acting chemically upon the blood, may pro- duce 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- The corrosives act much more energetically when concentrated than when dilute; and when the dilution is great they have no deleterious action. The degree of concentration in which the true poisons are taken is of little influence upon their action. Under the above definitions the strong mineral acids act as corrosives rather than as poisons. They produce their injurious results by destroying 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 symptoms of corrosion by the mineral acids begin immediately, during the act of swallowing. The chemical action of the acid upon every part with which it comes in contact causes acute burning pain, extending from the mouth CHLORINE 79 to the stomach and intestine, referred chiefly to the epigastrium. Violent and distressing vomiting of dark, tarry, or "coffee-ground," highly acid material is a prominent symptom. Eschars, at first white or gray, later brown or black, are formed where the acid has come in contact with the skin or mucous membrane. Respiration is labored and painful, partly by pressure of the abdominal mus- cles, but also, in the case of hydrochloric acid, from entrance of the irritating gas into the respiratory passages. Death may occur within twenty-four hours, from collapse; more suddenly from perforation of large blood-vessels, or from peritonitis; or after several weeks, secondarily, from starvation, due to closure of the pylorus by inflammatory thickening, and destruction of the gastric glands. 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 calcined magnesia, suspended in a small quantity of water, or if this is 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 plastered wall, or oil, are entirely useless. Any attempt at the introduction of a tube into the esophagus is attended with danger of perforation, except in the earliest stages of the intoxication. Compounds of Chlorine and Oxygen. Two compounds of chlorine and oxygen are known. They are both very unstable, and prone to sudden violent decomposition. Chlorine Monoxide. C1 2 87 HypoMorous anhydride, is formed by the action, below 20 , of dry Cl upon precipitated mercuric oxide: HgO~t-2Cl 2 =HgCl 2 +Cl 2 0. On contact with H,0 it forms hypochlorous acid, HC10, which owing to its instability, is not used industrially, although the hypo- chlorites of Ca, K, and Na are. Chlorine Tetroxide. Chlorine peroxide, C1 2 4 135 is a vio- lently explosive body, produced by the action, of sulphuric acid upon potassium chlorate. Below 20 it is an orange-colored liquid, above that temperature a yellow gas. It explodes violently when heated to a temperature below 100. There is no corresponding hydrate known, and if it be brought in contact with an alkaline hydroxide, a mixture of chlorate and chloride is formed. Besides the above, two oxy acids of Cl are known, the anhydrides corresponding to which have not been isolated. Chloric Acid HC10 3 84.5 obtained, in aqueous solution, as a strongly acid, yellowish, syrupy liquid, by decomposing barium chlorate by sulphuric acid: Ba(C10 3 ) 2 +H 2 S0 4 =BaS0 4 +2HC10 3 Perchloric Acid. HC10 4 100.5 is the most stable of the series. It is obtained by boiling potassium chlorate with hydrofluosilicic acid, decanting 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. 80 TEXT-BOOK OF CHEMISTRY BROMINE. Symbol= :Br. Atomic weight^ (International :79.92) Mo- lecular weight \^Q Sp. gr. of liquid=3.1812 at 0; of vapor 5.52 A. Occurrence. Only in combination, most abundantly with Na, K, Ca, and Mg in sea water and the waters of mineral springs. Preparation. It is obtained from the mother liquors, left by the evaporation of sea water, and of that of certain mineral springs, and from sea weed. Bromine may be prepared from the bromide of Na or K by heating with sulphuric acid and manganese dioxide: 2KBr+3H 2 S0 4 +Mn0 2 =2KHS0 4 +MnS0 4 +2H 2 0+Br 2 Properties. Physical. A dark reddish-brown liquid, volatile at all temperatures above 24.5 ; giving off brown-red vapors which produce great irritation when inhaled. Soluble in water to the ex- tent of 3.2 parts per 100 at 15; 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 (32 F): Br5H 2 0. Its aqueous solution is decomposed by ex- posure to light, with formation of hydrobromic acid. It is highly poisonous. Hydrogen Bromide Hydrobromic acid. = HBr Molecular weight=8l. Sp. gr. 2.71 A. 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 2 upon phosphorus tribromide : PBr 3 +3H 2 0=H 3 P0 3 +3HBr ; or by the action of Br upon paraffin. Properties. A colorless gas; produces white fumes with moist air; acid in taste and reaction, and readily soluble in H 2 0, with which it forms a hydrate, HBr2H 2 0. Its chemical properties are similar to those of HC1. The Acidum hydrobromicum dilutum of the U. S. P. (dilute hydrobromic acid) contains not less than 9.5 per cent, nor more than 10.5 per cent, of HBr. Bromides closely resemble the chlorides and are formed under similar conditions. They are decomposed by chlorine, with forma- tion of a chloride and liberation of Br: 2KBr+Cl 2 =2KCl+Br t . The metallic bromides arc soluble in H 2 0, except AgBr and HgBr, IODINE 81 which are insoluble, and PbBr 2 , which is sparingly soluble. The bromides of Mg, Al, Ca are decomposed into oxide and HBr on evaporation of their aqueous solutions. Bromidion Analytical Characters. Solutions of hydrobromic acid and of bromides contain the anion Br', which gives the follow- ing reactions: (1) With AgNO ;? , a yellowish white ppt., insoluble in HN0 3 , sparingly soluble in NH 4 OH. (2) With chlorine water a yellow solution which communicates the same color to chloroform and to starch-paste. 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 hydroxide no hypobromite is formed, but a mixture of bromate and bromide, having no decolorizing action. With sodium hydroxide, however, sodium hypobromite is formed in solution; and such a solution, freshly prepared, is used in Knop's process for determining urea. IODINE. lodum (U. S. P.) Symbol=l Atomic weight 127 (Interna- tamaZ=126.92). Molecular weight 254: S p. gr. of soZwZ=4.948; of vapor=S.116 A. 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 H 2 0, and the solution evaporated to small bulk. The mother liquor, when separated from the other salts which crystallize out, contains the iodides, which are decomposed by Cl, aided by heat, and the liberated iodine is con- densed. Iodine may be prepared from the iodide of Na or K by heating with sulphuric acid and manganese dioxide: 2KI+3H 2 S0 4 +Mn0 2 =2KHS0 4 +MnS0 4 +2H 2 0+I 2 Properties. Physical. Blue-gray, crystalline scales, having a metallic luster. Volatile at all temperatures, the vapor having a violet color and a peculiar odor. The density of vapor of iodine, at one atmosphere of pressure and at temperatures between its boiling point and about 500 is 254 (0=32), corresponding to the molecular formula I 2 , but above that temperature the density diminishes, until at 1,500 it has fallen to 127, corresponding to the molecular formula I, where it remains constant. Molecular iodine is, therefore, dis- sociated by heat. Iodine is very sparingly soluble in water, but the aqueous solution, standing over excess of iodine, continues to dis- solve it by reason of the formation of hydriodic acid. Solutions of hydriodic acid and of metallic iodides dissolve notably larger quan- tities of iodine than does pure water, probably because of the forma- 82 TEXT-BOOK OF CHEMISTRY tion of the ion I 3 '. Lugol's solution Liquor iodi compositus (U. S. P.) contains 5 parts of iodine and 10 parts of potassium iodide in 100 parts of water. Iodine is very soluble in alcohol, ether, chloro- form, benzene and carbon disulphide. With the three last named solvents the solutions are violet, with others brown in color. Chemical. In its chemical characters I resembles Cl and Br, but is less active. It decomposes H 2 slowly and is a weak bleaching and oxidizing agent. In presence of water, 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 hydroxide solution dissolves it, with formation of potas- sium iodide, and some hypoiodite. Nitric acid oxidizes it to iodic acid. With ammonium hydroxide solution it forms the explosive nitrogen iodide. 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 perspira- tion, and when taken in large quantity it appears in the feces. The poison should be removed as rapidly as possible by the use of the stomach tube and of emetics. Farinaceous substances may also be given. Hydrogen Iodide Hydriodic acid HI Molecular weight=128. Preparation. By the decomposition of phosphorus triiodide by water : PI 3 +3H 2 0-H 3 P0 3 +3HI Or, in solution by passing hydrogen sulphide through water holding iodine in suspension: H 2 S+2I 2 =S 2 +4HI Properties. A colorless gas, forming white fumes on contact with air, and of strongly acid reaction. Under the influence of cold and pressure it forms a yellow liquid, which solidifies at 55. Water dissolves it to the extent of 425 volumes for each volume of the solvent at 10. It is partly decomposed into its elements by heat. Mixed with it is decomposed, even in the dark, with formation of H 2 and libera- tion of I. Under the influence of sunlight the gas is slowly decom- posed, although its solutions are not so affected, if they be free from air. Chlorine and bromine decompose it, with liberation of iodi in*. 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. The Acidum hydriodicum dilutum (diluted hydriodic acid) of the U. S. P. contains not less than 9.5 per cent, nor more than 10.5 per cent, of HI. Iodides are formed under the same conditions as the chlorides and bromides, which they resemble in their properties. The metallic SULPHUR GROUP 83 iodides are -soluble in water except Agl, Hgl, which are insoluble, and PbI 2 , which is very slightly soluble. The iodides of the earth metals are decomposed into oxide and HI on evaporation of their aqueous solutions. Chlorine decomposes the iodides as it does the bromides. lodidion Analytical Characters. Solutions of hydriodic acid or of iodides contain iodidion, I', which forms a yellow ppt., insol. in HN0 3 and in NH 4 OH, with Ag'N0 3 . Brown solutions of excess of iodine in HI or KI contain triodidion, I 3 ', which, as iodine is removed from the solution, is decomposed into I'+I 2 . Aqueous or alcoholic solutions of free iodine, not of iodidion, color starch paste dark blue or black, and chloroform or carbon bisulphide violet. The same colors are produced with solutions of iodides after liberation from them of free iodine by fuming HN0 3 or chlorine water. At about 100 starch iodide is dissociated and decolorized, the color returning on cooling. Chlorides of Iodine. Chlorine and iodine combine with each other in two proportions: Iodine monochloride, or protochloride IC1 is a red-brown, oily, pungent liquid, formed by the action of dry Cl upon I, and distilling at 100. Iodine trichloride, or perchloride IC1 3 is a yellow, crystalline solid, having an astringent, acid taste and a penetrating odor; very volatile; its vapor irritating; easily soluble in water. It is formed by saturating H 2 O holding I in suspension with Cl, and adding concentrated sulphuric acid. IC1 3 has been used as an antiseptic. Oxyacids of Iodine. The best known of these are the highest two of the series iodic and periodic acids. lodic Acid HIO 3 176 is formed as an iodate, whenever I is dissolved in a solution of an alkaline hydroxide: I 6 -f6KOH=KIO 3 -f5KI-|-3H 2 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 H 2 O holding I in suspension. Iodic acid appears in white crystals, decomposable at 170, and quite soluble in H 2 O, the solution having an acid reaction, and a bitter, astringent taste. It is an energetic oxidizing agent, yielding up its O readily, with separa- tion of elementary I or of HI. It is used as a test for the presence of morphine. Periodic Acid HIO 4 192 is formed by the action of Cl upon an alkaline solution of sodium iodate. The sodium salt thus obtained is dissolved in nitric acid, treated with silver nitrate, and the resulting silver periodate is then decomposed with H 2 O. From the solution the acid is obtained in colorless crystals, fusible at 130, very soluble in water, and readily decomposable by heat. II. SULPHUR GROUP. SULPHUR. SELENIUM. TELLURIUM. The elements of this group are bivalent in most of their com- pounds ; in some they are quadrivalent or hexavalent. With hydrogen they form compounds composed of one volume of the element, in the 84 TEXT-BOOK OF CHEMISTRY form of vapor, with two volumes of hydrogen the combination being attended with condensation in volume of one-third. Mineral acids in which they occur are dibasic. They are all solids at ordi- nary temperatures. The relation of their compounds to each other is shown in the following table: H 2 S S0 2 SO 8 H 2 S0 2 H 2 S0 4 H 2 S0 4 H 2 Se Se0 2 SeO 3 H 2 SeO 3 H 2 SeO 4 H 2 Te Te0 2 TeO 3 H 2 TeO 3 H 2 TeO 4 Ilydro-ic acid. Dioxide. Trioxide. Hypo-ous acid, -ous acid. -ic acid. SULPHUR. Symbol=S Atomic weight=32 (International=32.Q6) . Molecu- lar weight=64: Sp. gr. of vapor=2.22 A. Occurrence. Free in crystalline powder, large crystals, or amorphous, in volcanic regions. In combination in sulphides and sul- phates, and in protein substances. Preparation. By purification of the native sulphur or decom- position of pyrites, natural sulphides of iron. Crude sulphur is the product of the first distillation. A second distillation, in more perfectly constructed apparatus, yields refined sulphur. During the first part of the distillation, while the air of the condensing chamber is still cool, the vapor of S is suddenly con- densed into a fine, crystalline powder, which is flowers of sulphur, sulphur sublimatum (sublimed sulphur) (U. S. P.). Later, when the temperature of the condensing chamber is about 114, the liquid S collects at the bottom, whence it is drawn off and cast into sticks of roll sulphur. Properties. Physical. Sulphur, also known as brimstone, is usually yellow in color. At low temperature, and in minute sub- division, as in the precipitated milk of sulphur, sulphur praecipitatum (U. S. P.), it is almost quite colorless. Its taste and odor are faint but characteristic. At 114 it fuses to a thin yellow liquid, which at 150-160 becomes thick and brown; at 330-340 it again becomes thin and light in color; finally it boils, giving off brownish yellow vapor at a temperature variously stated between 440 and 448. If heated to about 400 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 aniline, phenol, benzene, petroleum ether, and chloroform; readily soluble in sulphur chloride, S 2 C1 2 , and carbon disulphide. It dissolves in hot alcohol, and crystal- lizes from the solution, on cooling, in white prismatic crystals. It is dimorphous. When fused sulphur crystallizes it does so in oblique rhombic prisms. Its solution in carbon disulphide deposits it on evaporation in rhombic octahodra. The prismatic variety is of sp. gr. 1.95 and fuses at 120; the sp. gr. of the octahedral is 2.05 and SULPHUR 85 its fusing point 114.5. 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 0, it burns with a blue flame to sulphur dioxide, S0 2 . In H it burns with formation of hydrogen sulphide, H 2 S. The compounds of S are similar in constitution, and to some extent in chemical properties, to those of 0. In many organic substances S may replace 0, as in thiocyanic acid, CNSH, correspond- ing to cyanic acid, CNOH. Such compounds are designated by the syllable fhio; the syllable sulpho, in the name of a compound, indi- cates that it contains the bivalent group, S0 2 . 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. Hydrogen Sulphide sulphuretted hydrogen Sulphydric acid H 2 S Molecular weig7ii=34: Sp. #r.=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 mineral springs; and, occasionally, in small quantity, in the gases of the intestine. It is produced from proteins and other organic substances containing S by microbic action (sulphydric fermentation). Preparation. (1) By direct union of the elements; either by burning S an II, or by passing H through molj^ri S. (2) By the action of nascent H upon sulphuric acid, if the mixture become heated. (See Marsh test for arsenic.) (3) By the action of HC1 upon antimony trisulphide: Sb 2 S 3 +6HCl=2SbCl 3 +3H 2 S (4) By the action of dilute sulphuric acid upon ferrous sulphide: FeS+H 2 S0 4 =FeS0 4 +H 2 S This is the method generally used. (5) By the action of HC1 upon calcium sulphide: CaS+2HCl=CaCl 2 +H 2 S Properties. Physical. A colorless gas having the odor of rotten eggs and a disgusting taste; soluble in H 2 to the extent of 3.23 parts to 1 at 15 ; soluble in alcohol. Under 17 atmospheres pressure, or at 74 at the ordinary pressure, it liquefies; at 85.5 it forms white crystals. Chemical. Burns in air with formation of sulphur dioxide and water : 2H 2 S-f 30 2 =2S0 2 +2H 2 86 TEXT-BOOK OF CHEMISTRY If the supply of oxygen is deficient, H 2 is formed, and sulphur liberated : 2H 2 S+0 2 =:2H 2 0+S 2 Mixtures of H 2 S and air or explode on contact with flame. Solutions of the gas when exposed to air become oxidized with de- position of S. Such solutions should be made with boiled H 2 0, and kept in bottles which are completely filled, and well corked. Oxidizing agents, Cl, Br, and I remove its H with deposition of S. Hydrogen sulphide and sulphur dioxide mutually decompose each other into water, pentathionic acid and sulphur: 4S0 2 +3H 2 S=2H 2 0+H 2 S 5 6 +S 2 When the gas is passed through a solution of an alkaline hy- droxide its S displaces the of the hydroxide to form a sulphydrate : H 2 S+KOH=H 2 0+KHS With solutions of metallic salts H 2 S usually relinquishes its S to the metal : CuS0 4 +H 2 S=CuS+H 2 S0 4 a property which renders it of great value in analytical chemistry. Physiological. Hydrogen sulphide is produced in the intestine FIG. 12. by the decomposition of protein 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 2 S, and the diluted gas is still rapidly fatal. An atmosphere containing 1 per cent, may be fatal to man, although individuals habituated to its presence can exist in an atmosphere containing 3 per cent. Its toxic powers are due pri- marily, 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, arti- ficial respiration, cold affusions, and the administration of stimulants. After death the blood is found to be dark in color, and gives the spectrum shown in Fig. 12, due to sulphemoglobin. SULPHUR 87 Sulphides and Hydrosulphides. These compounds bear the same relation to sulphur that the oxides and hydroxides do to oxygen. The two sulphides of arsenic, As 2 S 3 and As 2 S 5 , correspond to the two oxides, As 2 3 and As 2 5 , and the potassium hydrosulphide, KHS, corresponds to the hydroxide, KOH. Many metallic sulphides occur in nature, and are important ores of the metals, as the sulphide of zinc, mercury, cobalt, nickel, and iron. They are formed artificially, either by direct union of the ele- ments at elevated temperatures, as in the case of iron: Fe-f-S=FeS; or by reduction of the corresponding sulphate, as in the case of calcium : CaS0 4 +2C=CaS+2C0 2 The sulphides are insoluble in H 2 0, except those of the alkali metals. Many of the sulphides are soluble in alkaline liquids, and behave as thio-anhydrides, forming thio-salts, corresponding to the oxysalts. Thus potassium arsenate, K 3 As0 4 , and thioarsenate, K 3 AsS 4 ; antimonate, K 3 Sb0 4 , and thioantimonate, K 3 SbS 4 . The metallic sulphides are decomposed when heated in air, usually with the formation of sulphur dioxide and the metallic oxide ; some- times with the formation of the sulphate; and sometimes with the liberation of the metal, and the formation of sulphur dioxide. The strong mineral acids decompose the sulphides with the formation of hydrogen monosulphide. 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 S0 2 . (2) With a mineral acid give off H 2 S (except sulphides of Hg, Au, and Pt). Sulphur Dioxide. Sulphurous oxide, or anhydride S0 2 Mo- lecular weight=64: Sp. gr. of gas=2.2l3 ; of liquid=lA5. Occurrence. In volcanic gases and in solution in some mineral waters. Preparation. (1) By burning S in air or 0. (2) By roasting iron pyrites in a current of air. (3) By heating sulphuric acid with copper: 2H 2 S0 4 +Cu=CuS0 4 +2H 2 0+S0 2 (4) By heating sulphuric acid with charcoal: 2H 2 S0 4 +C=2S0 2 +C0 2 +2H 2 When the gas is to be used as a disinfectant it is usually obtained by reaction (1) ; in sulphuric acid factories (2) is used; in the laboratory (3) is used. 88 TEXT-BOOK OF CHEMISTRY Properties. Physical. A colorless, suffocating gas, having a disagreeable and persistent taste. Very soluble in H 2 0, which at 15 dissolves about 40 times its volume (see below) ; also soluble in alcohol. At 10 it forms a colorless, mobile, transparent liquid, by whose rapid evaporation a cold of 65 is obtained. Liquid S0 2 packed in sealed tins or in siphons, is now a commercial article. Chemical. Sulphur dioxide is neither combustible nor a supporter of combustion. Heated with H it ijs decomposed: S0 2 +2H 2 =S+2H 2 With nascent hydrogen, H 2 S is formed : S0 2 +3H 2 =H 2 S+2H,0 Water not only dissolves the gas, but combines with it to form the true sulphurous acid, H->S0 3 . With solutions of metallic hydrox- ides it forms metallic sulphites: S0 2 +KOH=KHS0 3 ; or S0 2 -f 2KOH=K 2 S0 3 +H 2 0. A hydrate having the composition H 2 S0 3 , 8H 2 has been obtained as a crystalline solid, fusible at -(-4. Sulphur dioxide and sulphurous acid solution are powerful re- ducing agents, being themselves oxidized to sulphuric acid: S0 2 + H 2 0=H 2 S0 4 ; or H 2 SO 3 +0=H 2 S0 4 . It reduces nitric acid with formation of sulphuric acid and nitrogen tetroxide: S0 2 -|-2HN03= H 2 S0 4 -{-N 2 4 . It decolorizes organic pigments, without, however, destroying the pigment, whose color may be restored by an alkali or a stronger acid. It destroys H 2 S, acting, in this instance, not as a re- ducing but as an oxidizing agent: 4S0 2 +3H 2 S=2H 2 0+H 2 S B O fl ^S 2 . With Cl it combines directly under the influence of sunlight to form sulphuryl chloride (S0 2 )"C1 2 . Analytical Characters. (1) Odor of burning sulphur. (2) Paper moistened with starch paste and iodic acid solution turns blue in air containing 1 in 3,000 of S0 2 . Sulphur Trioxide. Sulphuric oxide or anhydride S0 3 Molecu- lar weight=80Sp. gr. 1.95. Preparation. (1) By union of SO 2 and at 250-300 or in presence of spongy platinum. (2) By heating sulphuric acid in presence of phosphoric an- hydride : H 2 S0 4 +P 2 5 =SO 3 +2HP0 3 (3) By heating dry sodium pyrosulphate : Na 2 S 2 7 =Na,SO 4 +S0 3 Properties. White, silky, odorless crystals which give off white fumes in damp air. It unites with H 2 with a hissing sound, and elevation of temperature, to form sulphuric acid. When dry it does not redden litmus. SULPHUR 89 Sulphur trioxide exists in two isomeric (see isomerism) modifica- tions, being one of the few instances of isomerism among mineral substances. The a modification, liquid at summer temperature, solidifies in colorless prisms at 16 and boils at 46. The ft isomere is a white, crystalline solid which gradually fuses and passes into the a form at about 50. Oxyacids of Sulphur. H 2 S0 2 Hyposulphurous acid. H 2 S 2 T Pyrosulphuric acid. H 2 S0 3 Sulphurous acid- H 2 S 2 Dithionic acid. H 2 SO 4 Sulphuric acid. H 2 S 3 O fl Trithionic acid. H 2 S,O 8 Persulphuric acid. H 2 S 4 O a Tetrathionic acid. H 2 S k 3 Thiosulphuric acid. H 2 S 5 6 Pentathionic acid. . The graphic formulae of the chief of these acids are appended : o/OH \\oXOH b \OH 0// b \OH Hyposulphurous acid. Sulphuric acid. Q /OH 0\\ Q /SH ^\OH 0// b \OH Sulphurous acid. Thiosulphuric acid. Hyposulphurous Acid H 2 S0 2 66. Hydro sulphurous acid Is an unstable body known only in solution, obtained by the action of zinc upon solution of sulphurous acid. It is a powerful bleaching and deoxidizing agent. Sulphurous Acid H 2 S0 3 82. Although sulphurous acid has not been isolated, it, in all probability, exists in the acid solution, formed when sulphur dioxide is dissolved in water: S0 2 -[-H 2 0= S0 3 H 2 . Its salts, the sulphides, are well defined. From the existence of certain organic derivatives (see sulphonic acids) it would seem that two isomeric modifications of the acid may exist. They are distin- guished as the symmetrical, in which the S atom is quadrivalent : _ s /OH s \OH' and the unsymmetrical, in which the S atom is hexavalent: 0\\ fi /H 0// b \OIT Sulphites. The sulphites are decomposed by the stronger acids, with evolution of sulphur dioxide. Nitric acid oxidizes them to sul- phates. The sulphites of the alkali metals are soluble, and are active reducing agents. N . The analytical characters of the sulphites (sulphosion) are: (1) With HC1 they give off S0 2 . (2) With zinc and HC1 they give off H,S. (3) With AgN0 3 they form a white ppt., soluble in excess of 90 TEXT-BOOK OF CHEMISTRY sulphite, and depositing metallic Ag when the mixture is boiled. (4) With Ba (N0 3 ) 2 they form a white ppt, soluble in HC1. If chlorine water is added to the solution so formed a white ppt., insoluble in acids, is produced. Sulphuric Acid Oil of Vitriol Acidum sulphuricum (U. S. P.) -H 2 S0 4 98. Preparation. (1) By the union of sulphur trioxide and water: S0 3 +H 2 0=H 2 S0 4 . (2) By the oxidation of S0 2 or of S in the presence of water: 2S0 2 +2H 2 0+0 2 =2H 2 S0 4 ; or S 2 +2H 2 0+30 2 =2H 2 S0 4 . The manufacture of H 2 S0 4 may be said to be the basis of all chemical industry, as there are but few processes in chemical tech- nology into some part of which it does not enter. The method fol- lowed at present, the result of gradual improvement, may be divided into two stages: (1) the formation of a dilute acid; (2) the con- centration 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 con- taining 65 per cent, of true sulphuric acid, H 2 S0 4 . Into these cham- bers S0 2 , 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 2 S0 4 , while nitrogen tetroxide (red fumes) is formed: S0 2 +2HN0 3 =H 2 S0 4 +N 2 4 Were this the only reaction, the disposal of the red fumes would present a serious difficulty and the amount of nitric acid consumed would be very great. A second reaction occurs between the red fumes and H 2 0, which is injected in the form of steam, by which nitric acid and nitrogen dioxide are produced : 3N 2 4 +2H 2 0=4HN0 3 +2NO The nitrogen dioxide in turn combines with to produce the tetroxide, which then regenerates a further quantity 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 from the air to the S0 2 , in such manner that the sum of the reactions may be represented by the following equation : 2S0 2 +2H 2 0+0 2 =2H 2 S0 4 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 industrial processes, is not yet strong enough for most pur- poses. It is concentrated, first, by evaporation in shallow leaden pans, until its sp. gr. reaches 1.746. At this point it begins to act SULPHUR 91 upon the lead, and is transferred to platinum stills, where the con- centration is completed. Varieties. Sulphuric acid is met with in several conditions of concentration and purity: (1) The commercial oil of vitriol, largely used in manufacturing processes, 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 99V 2 per cent, of true H 2 S0 4 . (2) C. P. acidAcidum sulphuricum (U. S. P.), of sp. gr. 1.83 at 25, and containing not less than 93 per cent, nor more than 95 per cent, of H 2 S0 4 , is colorless and comparatively pure (see below). (3) Glacial sulphuric acid is a hydrate of the composition H 2 S0 4 , H 2 0, sometimes called bihydrated sulphuric acid, which crystallizes in rhombic prisms, fusible at +8.5 when an acid of sp. gr. 1.788 is cooled to that temperature. (4) Diluted sulphuric acid (U. S. P.) is a dilute acid of sp. gr. 1.067 and containing 9.5 per cent. H 2 S0 4 (U. S. P.). (5) Aromatic sulphuric acid (U. S. P.) contains not less than 19 per cent, and not more than 21 per cent, of H 2 S0 4 . Properties. Physical. A colorless, heavy, oily liquid; sp. gr. 1.842 at 12; crystallizes at 10.5; boils at 338. 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 2 have a lower boiling point, and lower sp. gr. as the proportion of H 2 increases. Chemical. At a red heat vapor of H 2 S0 4 is partly dissociated into S0 3 and H 2 0; or, in the presence of platinum, into S0 2 , H 2 and 0. When heated with S, C, P, Hg, Cu, or Ag, it is reduced with formation of S0 2 . Sulphuric acid has a great tendency to absorb H 2 0, 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 2 produce an elevation of temperature to 130 and the resulting mixture occupies a volume 1-6 less than the sum of the volumes of the constituents. Strong H 2 S0 4 is a good desiccator of air or gases. It should not be left exposed in uncovered vessels, lest by increase of volume it overflow. It is by virtue of its affinity for H 2 that H 2 S0 4 chars or dehydrates organic substances. Sul- phuric acid is a powerful dibasic acid. The commercial acid is very impure. The colorless so-called C. P. acid may also contain: PbS0 4 , which forms a black ppt. when the dilute acid is treated with H 2 S; S0 2 , which gives off H 2 S when the dilute acid is added to Zn ; As, which appears as a mirror when the dilute acid is examined by Marsh's test; oxides of nitrogen, which communicate a red or pink color to pure brucine. 92 TEXT-BOOK OF CHEMISTRY Sulphates. Sulphuric acid being dibasic, there exist two sulphates of the univalent metals: HKSO 4 and K 2 S0 4 , and but one sulphate of each bivalent metal : CaS0 4 . The sulphates of Ba, Ca, Sr, and Pb are insoluble, or very sparingly soluble, in H 2 0. Other sulphates are soluble in H 2 0, but all are insoluble in alcohol. Analytical Characters. Because of the dibasic character of sul- phuric acid its solutions and those of its salts may contain two kinds of anion: S0 4 " in dilute solutions of the acid and in solutions of neutral sulphates, and S0 4 H' in concentrated solutions of the acid and in solutions of acid sulphates. In the following analytical re- actions it is immaterial which anion is present if the reaction bo only slightly acid, because then, as SO/' is removed by combination with the cations Ba", Pb", or Ca", the anion S0 4 H' is decom- posed to SO/+H'; but when the solution is strongly acid a small proportion of S0 4 H' may remain unprecipitated. (1) Barium chloride (or nitrate) ; a white ppt., insol. in dil. acids. The ppt., dried and heated with charcoal, forms BaS, which, with HC1, gives off H 2 S. (2) Plumbic acetate forms a white ppt., insol. in dil. acids. (3) Calcium chloride forms a white ppt., either immediately or upon dilution with two volumes of alcohol: insol. in dil. HC1 or HN0 3 . 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 esophagus, 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 page 79). Persulphuric Acid. H 2 S 2 8 194 is formed by the electrolysis of concentrated sulphuric acid: 2H 2 S0 4 =H 2 S 2 8 +H :! ; or by the action of hydrogen dioxide on sulphuric acid : 2H 2 S0 4 +H 2 2 =H 2 S 2 8 +2H 2 It crystallizes at in long, transparent needles. The correspond- ing anhydride, S 2 7 , is formed by the action of high tension electric currents in a mixture of dry S0 2 and 0. Thiosulphuric Acid. Hyposulphurous acid H 2 S 2 3 314 may be considered as sulphuric acid, H 2 S0 4 , in which one atom of oxygen has been replaced by one of sulphur. The acid itself has not been isolated, being decomposed, on liberation from the thiosulphates, into sulphur, water, and sulphur dioxide: H 2 S 2 3 =S+S0 2 +H 2 NITROGEN GROUP 93 Pyrosulphuric Acid. Fuming sulphuric acid Nordhausen oil of vitriol H 2 S 2 7 Molecular weigJit=H8Sp. #r.=1.9. Preparation. By distilling ferrous sulphate; and purification of the product by repeated crystallizations and fusions, until a sub- stance fusing at 35 is obtained. Properties. The commercial Nordhausen acid, which is a mix- ture of H 2 S 2 7 with excess of S0 3 , or of H 2 S0 4 , is a brown, oily liquid, which boils below 100 , giving off S0 3 ; and is solid or liquid according to the temperature. It is used chiefly as a solvent for indigo, and in the aniline industry. SELENIUM AND TELLURIUM. Se 79 (International=79.2) Te 127 (International=127.5) These are rare elements which form compounds similar to those of sulphur. Selenium is known in various allotropic modifications, and is used in some forms of electrical apparatus. III. NITROGEN GROUP. NITROGEN PHOSPHORUS ARSENIG-ANTIMONY. The elements of this group are trivalent or quinquivalent, occa- sionally univalent. 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 conden- sation of volume of one-half. Bismuth, frequently classed in this group, is excluded, owing to the existence of the nitrate Bi(N0 3 ) 3 . The relations existing between the compounds of the elements of this group are shown in the follow- ing table: NH 3 , N 2 O, NO, NA, N0 2 , N 2 5 , PH 3 , PA, PA, H 3 P0 2 , AsH 3 , AsA, AsA, SbH 3 , SbA, SbA, SbA, Hyd- Mon- Di- Tri- Tetr- Pent- Hypo-ous ride. oxide. oxide. oxide. oxide. oxide. acid. HN0 2 , HN0 3 , H 3 P0 3 , H 4 P 2 O 5 , H 3 P0 4 , H 4 P 2 7 , HPO 3 , H 3 As0 3 , H 4 As 2 5 , HAs0 2 , H 3 As0 4 , H 4 As 2 7 , HAs0 3 , HSb0 2 , H 3 Sb0 4 , H 4 Sb 2 7 , HSbO 3 , -ous Pyro-ous Meta-ous -Ic Pyro-ic Meta-ic acid. acid. acid. acid. acid. acid. 94 TEXT-BOOK OF CHEMISTRY NITROGEN. Azote Symbol=N Atomic weight=14: (International=14.Ql) Molecular weight 2SSp. #r.=0.9701. Occurrence. Free in atmospheric air and in volcanic gases. In combination in the nitrates, in ammoniacal compounds and in a great number of animal and vegetable substances. Preparation. (1) By removal of from atmospheric air; by burning P in air, or by passing air slowly over red-hot copper. It is contaminated with C0 2 , H 2 0, etc. (2) By passing Cl through excess of ammonium hydroxide solu- tion. If ammonia is not maintained in excess, the Cl reacts with the ammonium chloride formed, to produce the terribly explosive nitrogen chloride. (3) By heating ammonium nitrite (NH 4 )N0 2 : NH 4 NO 2 =2H 2 0+N 2 (4) By heating a mixture of ammonium chloride and potassium nitrite : KN0 2 +NH 4 C1=KC1+NH 4 N0 2 The ammonium nitrite then splits up as in (3). 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 com- pounds are very prone to decomposition, which may occur explo- sively or slowly. Nitrogen combines directly with under the influence of electric discharges; and with H under like conditions, and, directly, during the decomposition of nitrogenized organic sub- stances. It combines directly with magnesium, boron, vanadium, and titanium. Nitrogen is not poisonous, but is incapable of supporting respi- ration. Atmospheric Air. Composition. Air is not a chemical compound, but a mechanical mixture of O and N, with smaller quantities of other gases (see page 72). Leaving out of consideration vapor of water and small quantities of other gases, except 0.03 of carbon dioxide, air consists of 20.95 O and 79.02 N (including argon), by volume; or about 23 O and 77 N, by weight; proportions which vary but very slightly at different times and places. 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 well as by the solubility of air in water. 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 H 2 O according to its own solubility, and air dissolved in H 2 O at 14.1 consists of N and O, not in the proportion given above, but in the proportion of 66.76 to 33.24. Besides these two main constituents, air contains about 4-5 thousandths of NITROGEN 95 its bulk of other substances; vapor of water, carbon dioxide, ammoniacal com- pounds, hydrocarbons, ozone, oxides of nitrogen, and solid particles held in suspension. Vapor of Water. 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 H 2 O which a given volume of air can hold, without precipitation, varies according to the temperature and pressure. It happens rarely that air is as highly charged with moisture as it is capable of being for the existing temperature. The fraction of saturation, or hygrometric state, or relative humidity of the atmosphere is the percentage of that quantity of vapor of water which the air could hold at the existing temperature and pressure which it actually does hold. Thus air with a humidity of 100 is saturated, and a diminution of temperature or of pressure would cause precipi- tation; but an increase of temperature or of pressure would cause a diminution of humidity. Ordinarily air contains from 66 to 70 per cent, of its possible amount of moisture. If the quantity is less than this, the air is dry, and causes a parched sensation, and the sense of "stuffiness" so common in furnace- heated houses. If it be greater, evaporation 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 2 O in the volume of air used. The humidity is de- termined by instruments called hygrometers, hygroscopes 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.) For the newer gases in the air, see page 72. Ammoniacal Compounds. Carbonate, nitrate, and nitrite of ammonium occur in small quantity (0.1 to 6.0 parts per million of NH 3 ) 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 2 during discharges of atmospheric electricity. Rain- water, falling during thunder-showers, has been found to contain as much as 3.71 per million of HNO 3 . Sulphuric and Sulphurous acids occur, in combination with NH 4 , in the air over cities, and manufacturing districts, where they are produced by the oxidation of S, existing in coal and coal-gas. Solid particles of the most diverse nature are always present in air and become visible in a beam of sunlight. Sodium chloride is almost always present, always in the neighborhood of salt water. Air contains myriads of germc of vegetable organisms, mould, etc., which are propagated by the transportation of these germs by air-currents. Compounds of Nitrogen and Hydrogen. Three are known: Ammonia, NH 3 ; Hydrazine, N 2 H 4 ; and Hydrazoic acid, N 3 H ; as well as salts corresponding to two hydroxides. Ammonia. Hydrogen nitride Volatile alkali NH 3 Molecular weight Yl Sp. #r.=0.589 A. Preparation. (1) By union of nascent H with N. (2) By decomposition of organic matter containing N, either spontaneously or by destructive distillation. 96 TEXT-BOOK OF CHEMISTRY (3) By heating solution of ammonium hydroxide: NH 4 OH=NH 3 -f-H 2 0. (4) By heating a mixture of ammonium chloride and slaked lime: 2NH 4 Cl+Ca(OH) 2 =CaCl 2 +2H 2 0+2NH 3 Properties. Physical. A colorless gas, having a pungent odor, and an acrid taste. It is very soluble in H 2 0, 1 volume of which at dissolves 1050 vols. NH 3 , and at 15 727 vols. NH 3 . Alcohol and ether also dissolve it readily. Liquid ammonia is a colorless, mobile fluid, used in ice machines for producing artificial cold, the liquid absorbing 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 dis- charges of electricity. It is not readily combustible, yet it burns in an atmosphere of with a yellowish flame. Mixtures of NH 3 with 0, nitrogen monoxide, or nitrogen dioxide, explode on contact with flame. The solution of ammonia in H 2 constitutes a strongly alkaline liquid, known in the U. S. P. as aqua ammonias (ammonia water), which contains not less than 9.5 per cent, nor more than 10.5 per cent. NH 3 , and is possessed of strongly basic properties. It is neutralized by acids with the formation of crystalline salts, which are also formed, without liberation of hydrogen, by direct union of gaseous NH 3 with acid vapors. The ammoniacal salts and the alkaline base in aqua ammoniae are compounds of a radical, ammonium, NH 4 , which forms compounds corresponding to those of potassium or sodium. The compound formed by the union of ammonia and water is ammonium hydroxide, NH 4 OH: NH 3 +H 2 0=NH 4 OH ; and that formed by the union of hydrochloric acid and ammonia is ammonium chloride, NH 4 C1: NH 3 +HC1=NH 4 C1. A very delicate test for ammonia is Nessler's reagent. This is made by dissolving 35 gm. of potassium iodide and 13 gm. of mercuric chloride in 800 cc. H 2 0. A cold, saturated solution of mercuric chloride is then added, drop by drop, until the red precipitate formed no longer redisselves on agitation ; 160 gm. of potassium hydroxide are then dissolved in the liquid, which is finally made up to 1000 cc. It gives a yellow color with a mere trace of NH 3 , and a red-brown precipitate with a larger amount. Hydrazine Diamide H 2 N.NH 2 is known in the form of its hydroxide, corresponding to ammonium hydroxide, in the form of its salts and in numerous organic derivatives. The sulphate is produced by the action of H 2 SO 4 upon NITROGEN 97 triazoacetic acid, and the hydroxide by decomposition of the sulphate by caustic soda. The hydroxide is an oily liquid, intensely corrosive, capable of attacking glass, ft combines with acids to form well-defined salts, and precipitates many metals from solutions of their salts. It is an active poison. Hydrazoic Acid Azoimide N 3 H is a substance obtained from benzoyl- azoimide, which, although containing the same elements as ammonia, is dis- tinctly acid in character. It is a colorless liquid, boiling at 37, having a very pungent and unpleasant odor. It is extremely unstable and explodes with great violence. It reacts with metals, oxides, and hydroxides, as does hydro- chloric acid, to form nitrides, which, like the free acid, are very explosive. It is a very active poison. Hydroxylamine NH 2 OH 33. The amines and amides (q. v.) are com- pounds derived from ammonia by the substitution of radicals for a part or all of its hydrogen. The substance, which is intermediate in composition between ammonia and ammonium hydroxide, may be considered as ammonia, one of whose hydrogen atoms has been replaced by the radical hydroxyl, OH. It is obtained in aqueous solution by the union of nascent hydrogen with nitrogen dioxide: NO-j-H 3 rrrNH 2 HO ; or by the action of nascent hydrogen upon nitric acid: HNO 3 -f-3H 2 =2H 2 0-f-NH 2 HO. Hydroxylamine has been obtained in color- less, hygroscopic crystals at 33, by systematic rectification of the methyl alcohol solution under diminished pressure, and by distillation of the Zn double salt, ZnCl 2 , 2NH 2 HO with aniline. Its aqueous solution, which probably con- tains the corresponding hydroxide, NH 3 , OH, is strongly alkaline and behaves with regard to acids as does ammonium hydroxide solution, forming salts cor- responding to those of ammonium. Thus hydroxyl-ammonium chloride, NH 4 OC1, crystallizes in prisms or tables, fusible at 100, and decomposed into HC1, H 2 O and NH 4 C1 at a slightly higher temperature. It is a very powerful reducing agent. Compounds of Nitrogen with the Halogens. Nitrogen Chloride NC1 3 120.5 is formed by the action of excess of Cl upon NH 3 or an ammoniacal compound. It is an oily, light-yellow liquid; sp. gr. 1.653; has been distilled at 71. When heated to 96, when sub- jected 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. NBr 3 254 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 3 395 When iodine is brought in contact with ammonium hydroxide solution, a dark brown or black powder, highly 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 circum- stances it is mixed with compounds containing N, I,- and H. Oxides of Nitrogen. Five are known, forming a regular series: N 2 0, NO, N 2 3 , N 2 O 4 , N 2 5 . Of these two, the trioxide, N 2 3 , and pentcxide, N 2 5 , are anhydrides. Nitrogen Monoxide. Nitrogenii monoxidum (U. S. P.) Nitrous oxide Laughing gas N 2 Molecular weight = 44 Sp. gr. = 1.527 A. 98 TEXT-BOOK OF CHEMISTRY Preparation. By heating ammonium nitrate : (NH 4 )N0 8 =N 2 0+2H 2 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, and the gas formed should be passed through wash-bottles containing sodium hydroxide and ferrous sulphate. Properties. Physical. A colorless, odorless gas, having a sweetish taste soluble in H 2 0; more so in alcohol. Under a pres- sure of 30 atmospheres, at 0, it forms a colorless, mobile liquid which, when dissolved in carbon disulphide and evaporated in vacuo, produces a cold of 140. 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 2 is decomposed into its constituent elements, and the nature and relative proportions 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 exhilaration of spirits, frequently accom- panied by laughter, and a tendency to muscular activity, the patient sometimes becoming aggressive ; afterward there is complete anesthesia and loss of consciousness. It is much used, by surgeons and dentists, as an anesthetic in operations of short duration. Nitrogen Dioxide. Nitric oxide NO Molecular weight=2Q Sp. #r.=1.039 A. Preparation. By the action of copper on moderately diluted nitric acid in the cold: 3Cu+8HN0 3 =3Cu(N0 3 ) 2 +4H 2 0+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 2 ; more soluble in alcohol. The sp. gr. of the gas has been determined at 100 and has been found to be same as at ordinary temperature. This fixes the molecular weight at 30 and gives the formula NO, which is difficult to reconcile with the theory of valence. Were the formula doubled the constitution of this gas could be thus expressed: 0=N N=0. (See Nitrogen tetroxide.) It combines with 0, when mixed with that gas or with air, to form the reddish brown nitrogen tetroxide. It is absorbed by solu- tion of ferrous sulphate, to which it communicates a dark brown or NITROGEN 99 black color. It is neither combustible nor a good supporter of com- bustion, .although ignited C and P continue to burn in it, and the alkaline metals, when heated in it, combine with its with incan- descence. Nitrogen Trioxide. Nitrous anhydride. N 2 3 76 Is prepared by the direct union of nitrogen dioxide and oxygen at low tempera- tures, or by decomposing liquefied nitrogen tetroxide with a small quantity of H 2 at a low temperature : 4N0 2 +H 2 0=2HN0 3 +N 2 3 It is a dark indigo-blue liquid, which, boiling at about 0, is partly decomposed. It solidifies at 82. Nitrogen Tetroxide. Nitrogen peroxide. N 2 04 Molecular weight=92. Preparation. (1) By mixing one volume with two volumes NO ; both dry and ice-cold. (2) By heating perfectly dry lead nitrate, being also produced: 2Pb(N0 3 ) 2 =2PbO+4N0 2 +0 2 . (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 gas is red-brown, but becomes colorless at about 500. The red fumes, which are produced when nitric acid is de- composed by starch or by a metal, consist of N 2 4 , mixed with N 2 3 . The sp. gr. of the gas varies with the temperature and pressure. Values varying from 29.23 to 39.9 have been obtained (H=l). The molecular formula, N0 2 , calls for sp. gr. 23; N 2 4 for 46. These variations are due to the fact that the gas is dissociated at com- paratively low temperatures. The formula N 2 4 has been fixed as the correct one by the method of Raoult. It dissolves in nitric acid, forming a dark yellow liquid, which is blue or green if N 2 3 be also present. With S0 2 it combines to form a solid, crystalline com- pound, which is sometimes produced in the manufacture of H 2 S0 4 . This substance, which forms the lead chamber crystals, is a sub- stituted sulphurous acid, nitrosulphonic acid, N0 2 S0 2 OH (see sulphonic acids). A small quantity of H 2 decomposes N 2 4 into HN0 3 and N 2 3 , which latter colors it green or blue. A larger quantity of H 2 decomposes it into HN0 3 and NO. By bases it is transformed into a mixture of nitrite and nitrate: 2N0 2 +2KOH=KN0 2 +KNO S +H 2 It is an energetic oxidant, for which it is largely used. With 100 TEXT-BOOK OF CHEMISTRY certain organic substances it does not behave as an oxidant, but becomes substituted as an univalent radical; thus with benzene it forms nitro-benzene : C H 5 (N(X). Toxicology. The brown fumes given off during many processes, in which nitric acid is decomposed, are dangerous to life. 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 2 S0 4 , or absorbed by H 2 or an alkaline solution. An atmosphere contaminated wi'h 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. 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 2 S Molecular weight =108. Preparation. (1) By decomposing dry silver nitrate with dry Cl in an apparatus entirely of glass: 4AgN0 3 +2Cl 2 =4AgCl+0 2 +2N 2 O c . (2) By removing water from fuming nitric acid with phosphorus pentoxide : 6HN0 3 +PA=2H 3 P0 4 +3N 2 5 . Properties. Prismatic crystals at temperatures above 30. It is very unstable, being decomposed by a heat of 50; on contact with H 2 0, with which it forms nitric acid; and even spontaneously. Most substances which combine readily with remove that element from N 2 5 . Nitrogen Acids. Three are known, either free or in combination, corresponding to the three oxides containing uneven numbers of atoms : N 2 -|-H 2 O=2HNO Hyponitrous acid. N 2 3 +H 2 0=2HNO, Nitrous acid. N 2 S +H 2 0=2HNO, Nitric acid. Hyponitrous Acid HNO 31 Known only in combination. Sodium hyponitrite is formed by the action of sodium upon sodium nitrate, or nitrite : NaN0 3 +4Na+2H 2 0=NaNO+4NaOH Silver hyponitrite is formed by reduction of sodium nitrate by nascent H and decomposition with silver nitrate. NITROGEN 101 Nitrous Acid Metanitrons acid HN(X 47 has not been iso- lated, although its salts, the nitrites, are well-defined compounds: M'N0 2 6rM"(N0 2 ) 2 . The nitrites occur in nature, in small quantity, in natural waters ; where they result from the decomposition of nitrogenous organic sub- stances; also in saliva. They are produced by heating the corre- sponding nitrate, either alone or in the presence of a readily oxidizable metal, such as lead. Solutions of the nitrites are readily decomposed by the mineral acids, with evolution of brown fumes. They take up oxygen readily and are hence used as reducing agents. Solutions of potassium permanganate are instantly decolorized by nitrites. A mixture of thin starch paste and zinc iodide solution is colored blue by nitrites, which decompose the iodide, liberating the iodine. A solu- tion of metaphenylendiamine, in the presence of free acid, is colored brown by very minute traces of a nitrite, the color being due to the formation of triamido-azobenzene (Bismark brown). Nitric Acid. Aquafortis Acidum nitricum U. S. P. HN0 3 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 2 S0 4 . With moderate heat a portion of the acid is liberated: 2NaN0 3 +H 2 S0 4 =NaHS0 4 +NaN0 3 +HN0 3 , and at a higher temperature the remainder is given off: NaN0 3 +NaHS0 4 ==Na 2 S0 4 +HN0 3 This is the reaction used in the manufacture of HN0 3 . Varieties. Commercial a yellowish liquid, impure, and of two degrees of concentration: single aquafortis; sp. gr. about 1.25=39% HN0 3 ; and double aquafortis; sp. gr. about 1.4=64% HN0 3 . Fuming a reddish yellow liquid, more or less free from impurities; charged with oxides of nitrogen. Sp. gr. about 1.5. Used as an oxidizing agent. C. P. a colorless liquid, sp. gr. 1.522, which should respond favorably to the tests given below. Acidum nitri- cum, U. S. P. a colorless acid, of sp. gr. 1.403 at 25=67 to 69 per cent. HN0 3 . Properties. Physical. The pure acid is a colorless liquid: sp. gr. 1.522; boils at 86; solidifies at 40; gives off white fumes in damp air; and has a strong acid taste and reaction. Chemical. When exposed to air and light, or when strongly heated, HN0 3 is decomposed into N 2 4 ; H 2 and 0. Nitric acid is a valuable oxidant; 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. 102 TEXT-BOOK OF CHEMISTRY Most of the metals dissolve in HN0 3 as nitrates, a portion of the acid being at the same time decomposed into NO and H 2 : 4HN0 3 +3Ag=3AgN0 3 +NO+2H 2 0. The chemical activity of HN0 3 is much reduced, or even almost arrested, when the intervention of nitrous acid is prevented by the presence of carbamide. The so-called noble metals, gold and plati- num, are not dissolved by either HN0 3 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 : HN0 3 +3HC1=2H 2 0+NOC1+C1 2 and 2HN0 3 +6HC1 4H 2 0+2NOC1 2 +C1 2 with formation of nitrosyl chloride, NOC1, and bichloride, NOC1 2 , and nascent Cl; the last named combining with the metal. The acidum nitrohydrochloricum of the U. S. P. is a strong aqueous solution con- taining hydrochloric acid, nitric acid, nitrosyl chloride, and chlorine. There is also an acidum nitrohydrochloricum dilutum (U. S. P.), which is a diluted aqueous solution containing the same constituents as the stronger acid. Iron dissolves easily in dilute HN0 3 , but if dipped into the concentrated acid, it is rendered passive, and does not dissolve when subsequently brought in contact with the dilute acid. This passive condition is destroyed by a temperature of 40 (104 F.) or by contact with Pt, Ag or Cu. When HN0 3 is decom- posed by zinc or iron, or in the porous cup of a Grove battery, N.,0 3 and N 2 4 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 color the acid yellow: H 2 S0 4 gives a white ppt. with BaCl 2 ; Cl, a white ppt. with AgNO 3 ; and Fe a red color with ammo- nium thiocyanate. Dilute the acid with two volumes of water before testing. Salts leave a solid residue when the acid is evaporated in platinum. Nitrates. The nitrates of K and Na occur in nature. Nitrates are formed by the action of HN0 3 on the metals, or on their oxides or carbonates. They have the composition M'N0 3 , M"(N0 3 ) 2 or M'"(N0 3 ) 8 , except certain basic salts, such as the sesquibasic lead- nitrate, Pb (N0 3 ) 2 , 2PbO. With the exception of a few basic salts, the nitrates are all soluble in water. When heated, they fuse and act as powerful oxidants. They are decomposed by H 2 S0 4 with libera- tion of HNO.,. Analytical Characters. As the nitrates are all soluble, there is no precipitation reaction for the anion N0 3 ', and recourse is had to color reactions: (1) Add an equal volume of concentrated IL,S0 4 , cool, and float on the surface of the mixture a solution of FeS0 4 . PHOSPHORUS 103 The lower layer becomes gradually colored brown, black, or purple, beginning 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 sus- pected solution and boil again; the color is discharged. (3) If acid, neutralize with KOH, evaporate to dryness, add to the residue a few drops of H 2 S0 4 and a crystal of brucine (or some sulphanilic acid) ; a red color is produced. (4) Add H,S0 4 and Cu to the suspected liquid and boil, brown fumes appear (best visible by looking into the mouth of the test tube). (5) A solution of diphenylamine in concentrated H 2 S0 4 (.01 grm. in 100 cc.) is colored blue by nitric acid. A similar color is produced by other oxidizing agents. (6) To 0.5 cc. nitrate solution add one drop aqueous solution of resorcinol (10%), and 1 drop HC1 (15%), and float on the surface of 2 cc. concentrated H 2 S0 4 ; a purple-red band. 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 rapidly 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 impor- tant function of the parts, is followed by more serious results (unless a large cutaneous surface is 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 H 2 SO 4 or HC1 have been taken, i..e., neutralization of the corrosive by magnesia or soap, and dilution. PHOSPHORUS. Symbol=P Atomic weight=%\ (International=31.Q4) Molecu- lar iveight=124: (PJSp. gr. of vapor 4.2904 A. Occurrence. Only in combination ; in the mineral and vegetable worlds as phosphates of Ca, Mg, Al, Pb, K, Na. In the animal kingdom as phosphates of Ca, Mg, K and Na, and in organic com- bination. Preparation. From bone-ash in which it occurs as tricalcic phosphate. Three parts of bone-ash are digested with 2 parts of strong H 2 S0 4 , diluted with 20 volumes H 2 0, when insoluble calcic sulphate and the soluble monocalcic phosphate, or "superphosphate," are formed: Ca 3 (P0 4 ) 2 +2H 2 S0 4 =CaH 4 (P0 4 ) 2 +2CaS0 4 The solution of superphosphate is filtered off and evaporated, the 104 TEXT-BOOK OF CHEMISTRY residue is mixed with about one-fourth its weight of powdered char- coal and sand, and the mixture heated, first to redness, finally to a white heat, in earthenware retorts, whose beaks dip under water in suitable receivers. During the first part of the heating the mono- calcic phosphate is converted into metaphosphate : CaH 4 (P0 4 ) 2 =Ca(P0 3 ) 2 +2H 2 0, which is in turn reduced by the charcoal, with formation of carbon monoxide and liberation of phosphorus, while the calcium is com- bined as silicate : 2Ca(P0 3 ) 2 +2Si0 2 +5C 2 =2CaSi0 3 +10CO+P 4 A direct electric process has, in great part, replaced the above industrially. A mixture of phosphate, carbon and flux is heated in a closed electric furnace provided with a condenser. The process is continuous and avoids the use of H 2 S0 4 . The crude product is purified by fusion, first under a solution of bleaching powder, next under ammoniacal H 2 0, and finally under water containing a small quantity of H 2 S0 4 and potassium dichro- mate. It is then strained through leather and cast into sticks under warm H 2 0. Properties. Physical. Phosphorus is capable of existing in four allotropic forms: (1) Ordinary, or yellow variety, in which it usually occurs in com- merce. This is a yellowish, translucid solid, of the consistency of wax. Below it is brittle; it fuses at 44.3; and boils at 290 in an atmosphere not capable of acting upon it chemically. Its vapor is colorless; sp. gr.=4.5A 65 H at 1040. It volatilizes below its boiling point, and H 2 boiled upon it gives off steam charged with its vapor. Exposed to air it gives off white fumes and produces ozone. It is luminous in the dark. It is insoluble in H 2 ; sparingly soluble in alcohol, more soluble in ether ; soluble in carbon disulphide, and in the fixed and volatile oils. It crystallizes on evaporation of its solutions in octahedrae or dodecahedrae. Sp. gr. 1.83 at 10. (2) White phosphorus is formed as a white, opaque pellicle upon the surface of the ordinary variety, when this is exposed to light under aerated H 2 0. Sp. gr. 1.515 at 15. When fused it reproduces ordinary phosphorus without loss of weight. (3) Black variety is formed when ordinary phosphorus is heated to 70 and suddenly cooled. (4) Red variety is produced from the ordinary by maintaining it at from 240 to 280 for two or three days, in an atmosphere of carbon dioxide; and, after cooling, washing out the unaltered yellow phosphorus with carbon disulphide. It is also formed upon the surface of the yellow variety, when it is exposed to direct sunlight. It is a reddish, odorless, tasteless solid, which does not fume in air, nor dissolve in the solvents of the yellow variety. Sp. gr. 2.1. PHOSPHORUS 105 Heated to 500 with lead, in the absence of air, it dissolves in the molten metal, from which it separates on cooling in violet-black, rhombohedral crystals, of sp. gr. 2.34. If prepared at 250 it fuses below that temperature, and at 260 is transformed into the yellow variety, which distils. The crystalline product does not fuse. It is not luminous at ordinary temperatures. Chemical. The most prominent property of P is the readiness with which it combines with 0. The yellow variety ignites and burns with a bright flame if heated in air to 60, or if exposed in a finely-divided state to air at the ordinary temperature; with forma- tion of P 2 3 ; P 2 5 ; H 3 P0 3 , or H 3 P0 4 , according as is present in excess or not, and according as the air is dry or moist. The tem- perature of ignition of yellow P is so low that it must be preserved under boiled water. By directing a current of upon it, P may be burned under H 2 0, heated above 45. The red variety combines with much less readily, and may be kept in contact with air without danger. The luminous appearance of yellow P is said to be due to the formation of ozone. It does not occur in pure at the ordinary temperature, nor in air under pressure, nor in the absence of mois- ture, nor in the presence of minute quantities of carbon disulphide, oil of turpentine, alcohol, ether, naphtha, and many gases. Yellow phosphorus burns in Cl with formation of PC1 3 or PC1 5 , according as P or Cl is present in excess. Both yellow and red varieties combine directly with Cl, Br, and I. Phosphorus is not acted on by HC1 or cold H 2 S0 4 . Hot H 2 S0 4 oxidizes it with formation of phosphorous acid and sulphur dioxide: P 4 +6H 2 S0 4 =4H 3 P0 3 +6S0 2 . Nitric acid oxidizes it violently to phosphoric acid and nitrogen di- and tetr-oxides: 12HN0 3 +P 4 =4H 3 P0 4 +4N 2 4 +4NO. Phosphorus is a reducing agent. When immersed in cupric sul- phate solution, it becomes covered with a coating of metallic copper. In silver nitrate solution it produces a black deposit of silver phosphide. The principal uses of phosphorus are in making matches, rat paste and phosphor bronze. Toxicology. The red variety differs from the other allotropic forms of phosphorus in not being poisonous, probably owing to its insolubility, and in being little liable to cause injury by burning. The burns produced by yellow phosphorus are more serious than a like destruction of cutaneous surface by other substances. A burning fragment of P adheres tenaciously to the skin, into which it burrows. One of the products of the combustion is metaphosphoric acid (q.v.) which, being absorbed, gives rise to true poisoning. Burns by P should be washed immediately with dilute Javelle water, liquor sodse chlorinatae, or solution of chloride of lime. Yellow 106 TEXT-BOOK OF CHEMISTRY P should never be allowed to come in contact with the skin, except under cold water. Yellow P is one of the most insidious of poisons. It is taken or adminis- tered usually as " ratsbane " or match-heads. The former is frequently starch paste, charged with phosphorus; the latter, in the ordinary sulphur match, a mixture of potassium chlorate, very fine sand, phosphorus, and a coloring matter. The symptoms in acute phosphorus-poisoning appear with greater or less rapidity, according to the dose, and the presence or absence in the stomach of substances which favor its absorption. Their appearance may be delayed for days, but as a rule they appear within a few hours. A disagreeable garlicky taste in the mouth, and heat in the stomach are first observed, the latter gradually de- veloping into a burning pain, accompanied by vomiting of dark-colored matter, which, when shaken in the dark, is phosphorescent; low temperature and dilata- tion of the pupils. In some cases, death follows at this point suddenly, without the appearance of any further marked symptoms. Usually, however, the patient rallies, seems to be doing well, until, suddenly, jaundice makes its appearance, accompanied by retention of urine, and frequently delirium, followed by coma and death. There is no known chemical antidote to phosphorus. The treatment is, therefore, limited to the removal of the unabsorbed portions of the poison by the action of an emetic, zinc or copper sulphate, or apomorphine, as expeditiously as possible, and the administration of French oil of turpentine the older the oil the better as a physiological antidote. The use of fixed oils or fats is to be avoided, as they favor the absorption of the poison, by their solvent action. The prognosis is very unfavorable. Analysis. When, after a death supposed to be caused by phosphorus, chemical evidence of the existence of the poison in the body, etc., is desired, the investigation must be made as soon after death as possible, for the reason that the element is rapidly oxidized, and the detection of the higher stages of oxidation of phosphorus is of no value as evidence of the administration of the element, because they are normal constituents of the body and of the food. Chronic phosphorus poisoning, or Lucifer disease, occurs among operatives engaged in the dipping, drying, and packing of phosphorus matches. Those engaged in the manufacture of phosphorus itself are not so affected. Sickly women and children are most subject to it. The cause of the disease has been ascribed to the presence of arsenic, and to the formation of oxides of phos- phorus, and of ozone. The progress of the disorder is slow, and its culminating manifestation is the destruction of one or both maxillae by necrosis. The frequency of the disease may be in some degree diminished by thorough ventilation of the shop, by frequent washing of the face and mouth with a weak solution of sodium carbonate, by exposing oil of turpentine in saucers in the workshops, and particularly by keeping the teeth in repair. None of these methods, however, effect a perfect prevention, which can only be attained by the substitution of the red variety of phosphorus for the yellow in this industry. Hydrogen Phosphides. Gaseous hydrogen phosphide Phos- phine. PH 3 34 a colorless gas, having a strong alliaceous odor, which is obtained pure by decomposing phosphonium iodide, PH 4 I, with H 2 0. Mixed with H and vapor of P 2 H 4 , it is produced, as a spontaneously inflammable gas, by the action of hot, concentrated solution of potassium hydroxide on P, or by decomposition of calcium phosphide by H 2 0. It is highly poisonous. After death, the blood is found to be of a dark violet color, and also to have, in a great measure, lost its power of absorbing oxygen. PHOSPHORUS 107 Liquid hydrogen phosphide P 2 H 4 66 is the substance whose vapor communicates to PH 3 its property of igniting on contact with air. It is separatee! by passing the spontaneously inflammable PH 3 through a bulb tube, surrounded by a freezing mixture. It is a colorless, heavy liquid, which is decomposed by exposure to sunlight, or to a temperature of 30. Solid hydrogen phosphide P 4 H 2 126 is a yellow solid, formed when P 2 H 4 is decomposed by sunlight. It is not phosphorescent and only ignites at 160. Compounds of Phosphorus with the Halogens Phosphorus Trichloride PC1 3 137.5 is obtained by heating P in a limited supply of Cl. It is a color- less liquid; sp. gr. 1.61; has an irritating odor; fumes in air; boils at 76. Water decomposes it with formation of H 3 P0 3 and HC1. Phosphorus Pentachloride PC1 5 208.5 is formed when P is burnt in excess of Cl. It is a light yellow, crystalline solid: gives off irritating fumes; and is decomposed by H 2 O. Phosphorus Oxychloride POC1 3 153.5 is formed by the action of a limited quantity of H 2 on the pentachloride: PC1 5 +H 2 0=POC1 3 +2HC1. It is a colorless liquid: sp. gr. 1.07; boils at 110, and solidifies at 10. Oxides of Phosphorus. Two are known: P 2 3 and P 2 5 . Phosphorus Trioxide. Phosphorous anhydride, Phosphorous oxide P 2 3 110 is formed when P is burned in a very limited supply of perfectly dry air, or 0. It is white, flocculent solid, which, on exposure to air, ignites by the heat developed by its union with H.,0 to form phosphorous acid. Phosphorus Pentoxide. Phosphoric anhydride, Phosphoric oxide P 2 5 142 is formed when P is burned in an excess of dry 0. It is a white, flocculent solid, which has almost as great a tendency to combine with H 2 as has P 2 3 . It absorbs moisture rapidly, deli- quescing to a highly acid liquid, containing, not phosphoric, but metaphosphoric acid. It is used as a drying agent. Phosphorus Acids. Six oxyacids of phosphorus are known: /O H /o H Hypophosphorous acid: 0=P H 0=P H \ H \ Pyrophosphoric acid: \O /O H 0=P H Phosphorous acid: O=P O H \O H \H /O H /O H 0=P H Phosphoric acid: 0=P O H , , . ., \ \O H Hypophosphoric acid: ^,O P O H /O H \0 H Metaphosphoric acid: O=P=O Only those H atoms which are connected with the P atoms through atoms are basic. Hence H 3 P0 2 is monobasic; H 3 P0 3 is dibasic ; H 3 P0 4 is tribasic ; H 4 P 2 7 is tetrabasic ; HP0 2 is monobasic, and H 4 P 2 C is tetrabasic. 108 TEXT-BOOK OF CHEMISTRY Hypophosphorous Acid. H 3 P0 2 66 is a crystalline solid, or, more usually, a strongly acid, colorless syrup. It is oxidized by air to a mixture of H 3 P0 3 and H 3 P0 4 . The acidum hypophosphorosum (U. S. P.) is an aqueous solution containing not less than 30 per cent, nor more than 32 per cent, of H 3 P0 2 ; and the acidum hypophosphorosum dilutum (U. S. P.) is an aqueous solution containing not less than 9.5 per cent, nor more than 10.5 per cent, of H 3 P0 2 . The hypophosphites, as well as the free acid, are powerful re- ducing agents. Phosphorous Acid H 3 P0 3 82 is formed by decomposition of phosphorus trichloride by water: PC1 3 +3H 2 0=3HC1+H 3 P0 3 It is a highly acid syrup, is decomposed by heat, and is a strong reducing agent. Phosphoric Acid Orthophosphoric acid Acidum phosphoricum (U. S. P.) H 3 P0 4 98 does not occur free in nature, but is widely disseminated in combination, in the phosphates, in the three king- doms of nature. It is prepared: (1) By converting bone phosphate, Ca 3 (P0 4 ) 2 into the corresponding lead or barium salt Pb 3 (P0 4 ) 2 or Ba 3 (P0 4 ) 2 , and decomposing the former by H 2 S, or the latter by H 2 S0 4 . (2) By oxidizing P by dilute HN0 3 , aided by heat: 3P 4 +20HN0 3 +8H 2 0=20NO+12H 3 P0 4 The operation should be conducted with caution, and heat gradually applied by the sand bath. It is best to use red phosphorus. The concentrated acid is a colorless, transparent, syrupy liquid; still containing H 2 0, which it gives off on exposure over H 2 S0 4 , leav- ing the pure acid, in transparent, deliquescent, prismatic crystals. It is decomposed by heat to form, first, pyrophosphoric acid, then metaphosphoric acid. It is tribasic. If made from arsenical phosphorus, and commercial phosphorus is arsenical unless made by the electrolytic method (p. 20), it is contaminated with arsenic acid, whose presence may be recognized by Marsh's test (q. v.). The acid should not respond to the indigo and ferrous sulphate tests for HN0 3 . The acidum phosphoricum (U. S. P.) contains not less than 85 per cent, nor more than 88 per cent, of H 3 P0 4 ; and the acidum phosphoricum dilutum (U. S. P.) contains not less than 9.5 per cent, nor more than 10.5 per cent, of H 3 P0 4 . Ortho-acids are those in which the number of hydroxyls equals the valence of the acidulous elements. Thus orthophosphoric acid is P(OH) r , ; orthocarbonic acid, C(OH) 4 . Sometimes, as in the case of phosphorus, when this acid is not known, that in which the PHOSPHORUS 109 number of Tiydroxyls most nearly equals the valence of the acidulous element .is, improperly, called the ortho-acid. Phosphates. Phosphoric acid being tribasic, the phosphates have the composition M'H,P0 4 ; M' 9 HP0 4 ; M' 3 P0 4 ; M"(H 2 P0 4 ) 2 ; M" 2 (HP0 4 ) 2 ; M" 3 (PO 4 ) 2 ; M"M'P0 4 ; and M"'P0 4 . The mono- metallic salts are all soluble and are strongly acid. Of the dimetallic salts, those of the alkali metals only are soluble and their solutions are faintly alkaline; the others are unstable, and exhibit a marked tendency to transformation into monometallic or trimetallic salts. The normal phosphates of the alkali metals are the only soluble tri- metallic phosphates. Their solutions are strongly alkaline, and they are decomposed even by weak acids: Na 3 P0 4 -f C0 3 H 2 Na 2 HP0 4 -f NaHCO, Trisodic Carbonic Disodic Monosodic phosphate. acid. phosphate. carbonate. All the monometallic phosphates, except those of the alkali metals, are decomposed by ammonium hydroxide, with precipitation of the corresponding trimetallic salt. Analytical Characters. (1) With ammoniacal solution of silver nitrate, a yellow precipitate. (2) With solution of ammonium molybdate in HN0 3 , a yellow precipitate. (3) With magnesia mix- ture,* a white, crystalline precipitate, soluble in acids, insoluble in ammonium hydroxide. Pyrophosphoric Acid H 4 P 2 7 178. When phosphoric acid (or hydro-disodic phosphate) is maintained at 213, two of its molecules unite, with the loss of the elements of a molecule of water: 2H 3 P0 4 = H 2 0-f H 4 P 2 7 , to form pyrophosphoric acid. Metaphosphoric Acid Glacial phosphoric acid HP0 3 80 is formed by heating H 3 P0 4 or H 4 P 2 7 to near redness : H 3 P0 4 =HP0 3 +H 2 ; or H 4 P 2 7 =2HP0 3 +H 2 0. It is usually obtained from bone phosphate; this is first converted into ammonium phosphate, which is then subjected to a red heat. It is a white, glassy, transparent solid, odorless and acid in taste and reaction. Slowly deliquescent in air, it is very soluble in H 2 0, although the solution takes place slowly, and is accompanied by a peculiar crackling sound. In constitution and basicity it resembles HN0 3 . Hypophosphoric Acid H 4 P 2 6 162. When phosphorus is ex- posed to moist air a strongly acid liquid is slowly formed, known as phosphatic acid. This is a mixture of phosphorous, phosphoric and hypophosphoric acids. The last named is separated from the others by taking advantage of the sparing solubility of its acid sodium salt ; this is then converted into the lead salt, which is decomposed by H 2 S, * Made by dissolving 11 pts. crystallized magnesium chloride and 28 pts. ammonium chloride in 130 pts. water, adding 70 pts. dilute ammonium hydroxide (sp. gr. 0.96) and filter- ing after two days. 110 TEXT-BOOK OF CHEMISTRY and the liberated acid concentrated. It has not been crystallized. It is quite stable at the ordinary temperature, but slowly decomposes to a mixture of phosphorous and pyrophosphoric acids. It is quadri- basic. It may be considered as formed by the union of a molecule of phosphoric acid and one of phosphorous acid, with loss of H 2 0: H 3 P0 4 +H 3 P0 3 =H 4 P 2 6 +H 2 0. ARSENIC. Symbol As Atomic weight=15 (International^ A. 96) Molec- ular weight=30Q (As 4 ) Sp. gr. of solid; crystalline 5.75, amor- ; of vapor=W.6 A at 860. Occurrence. Free in small quantity ; in combination as arsenides of Fe, Co, and Ni, but most abundantly in the sulphides, orpiment and realgar, and in arsenical iron pyrites, or mispickel. Preparation. (1) By heating mispickel in clay cylinders, which communicate with sheet iron condensing tubes. (2) By heating a mixture of arsenic trioxide and charcoal; and purifying the product by resublimation : 2As 2 3 +6C=6CO+As 4 Properties. Physical. A brittle, crystalline, steel-gray solid, having a metallic luster, or a dull, black, amorphous powder. At the ordinary pressure, and without contact of air, it volatilizes without fusion at 180; under strong pressure it fuses at a dull red heat. Its vapor is yellowish, and has the odor of garlic. It is insoluble in H 2 0, and in other liquids unless chemically altered. Chemical. Heated in air it is converted into the trioxide, and ignites somewhat below a red heat. In it burns with a brilliant, bluish-white light. In dry air it is not altered, but in the presence of moisture its surface becomes tarnished by oxidation. In H 2 it is slowly oxidized, a portion of the oxide dissolving in the water. It combines readily with Cl, Br, I, and S, and with most of the metals. With H it only combines when that element is in the nascent state. Warm, concentrated H 2 S0 4 is decomposed by As, with formation of S0 2 , As 2 3 , and H 2 0. Nitric acid is readily decomposed, giving up its to the formation of arsenic acid. With hot HC1, arsenic tri- chloride is formed. When fused with potassium hydroxide, arsenic is oxidized, H is given off, and a mixture of potassium arsenite and arsenide remains, which by greater heat is converted into arsenic, which volatilizes, and potassium arsenate, which remains. Elementary arsenic enters into the composition of fly poison and of shot, and is used in the manufacture of certain pigments and fire- works. Compounds of Arsenic and Hydrogen. Two are known: the solid As 2 H 2 ( ?) and the gaseous AsH 3 . ARSENIC 111 Hydrogen Arsenide Arsine Arseniuretted hydrogen AsH 3 Molecular weight =18 Sp. #r.=2.695 A. Formation. (1) By the action of dilute HC1 or H 2 S0 4 upon the arsenides of Zn and Sn. This is practically the same as 2, nascent hydrogen being formed by the action of the metal upon the acid. (2) Whenever a reducible compound of arsenic is in presence of nascent hydrogen. (See Marsh test.) (3) By the action of H 2 upon the arsenides of the alkali metals. (4) By the action of hot solution of potassium hydroxide upon reducible compounds of As in the presence of zinc. Properties. Physical. A colorless gas; having a strong allia- ceous odor; soluble in 5 vols. of H 2 0, free from air. Chemical.-. It is neutral in reaction. In contact with air and moisture its H is slowly removed by oxidation, and elementary As deposited. It is also decomposed into its elements by the passage through it of luminous electric discharges; and when subjected to a red heat. It is acted on by dry O at ordinary temperatures with the formation of a black deposit, which is at first solid hydrogen arsenide, later elementary As. A mixture of As H 3 and 0, containing 3 vols. and 2 vols. AsH 3 , explodes when heated, forming As 2 3 and H 2 0. If the proportion of be less, elementary As is deposited. The gas burns with a greenish flame, from which a white cloud of arsenic trioxide arises. A cold surface, held above the flame, becomes coated with a white, crystalline deposit of the oxide. If the flame is cooled by the introduction of a cold surface into it, the H alone is oxidized, and elementary As is deposited. Chlorine decomposes the gas explosively, with formation of HC1 and arsenic, or arsenic tri- chloride, if the Cl is in excess. In the presence of H 2 0, arsenous and arsenic acids are formed. Bromine and iodine behave similarly, but with less violence. All oxidizing agents decompose it readily; H 2 and arsenic tri- oxide being formed by the less active oxidants, and H 2 and arsenic acid by the more active. Solid potassium hydroxide decomposes the gas partially, and becomes coated with a dark deposit, which seems to be elementary arsenic. Solutions of the alkaline hydroxides absorb and decompose it; H is given off and an alkaline arsenite remains in the solution. Many metals, when heated in H 3 As, decompose it with formation of a metallic arsenide and liberation of hydrogen. Solution of silver nitrate is reduced by it; elementary silver is de- posited, and the solution contains silver arsenite. Although H 2 S and H 3 As decompose each other to a great extent, with formation of arsenic trisulphide, in the presence of air, the two gases do not act upon each other at the ordinary temperature, even in the direct sunlight, either dry or in the presence of H 2 0, when air is absent. Hence in making H 2 S for use in toxicological analysis, materials free from As must be used ; or the H 2 S must be purified. 112 TEXT-BOOK OF CHEMISTRY Compounds of Arsenic with the Halogens. Arsenic Trichloride AsCIj 181.5. Obtained by distilling a mixture of As 2 O 3 , H 2 SO, and NaCl, using a well-cooled receiver. It is a colorless liquid, boils at 134, fumes when exposed to the air, and volatilizes readily at temperatures below its boiling point. Its formation must be avoided in processes for the chemico-legal detection of arsenic, lest it In- volatilized and lost. It is formed by the action of HC1, even when comparatively dilute, upon As 2 O 3 at the temperature of the water-bath; but, if potassium chlorate be added, the trioxide is oxidized to arsenic acid, and the formation of the chloride thus prevented. Arsenic trioxide, when fused with sodium nitrate, is converted into sodium arsenate, which is not volatile. If, however, small quantities of chlorides be present, AsCl 3 is formed. It is highly poisonous. Arsenic Triodide Arsenii lodidum, U. S. P. AsI 3 456. Formed by adding As to a solution of I in carbon bisulphide, or by fusing together As and I in proper proportions. A brick-red solid, fusible and volatile. Soluble in a large quantity of H 2 O. Decomposed by a small quantity of H 2 into HI, As 2 O 8 , H 2 and a residue of AsI 8 . Compounds of Arsenic and Oxygen. Two are known: As,0 : , and As 2 0,j. Probably the gray substance formed by the action of moist air on elementary arsenic is a lower oxide. Arsenic Trioxide Arsenous anhydride Arsenous oxide White arsenic Arsenic As 2 3 198. Preparation. (1) By roasting the native sulphides of arsenic in a current of air: 2As 2 S 3 +90 2 =6S0 2 +2As 2 3 (2) By burning arsenic in air or oxygen. Properties. Physical. It occurs in three forms: crystallized or "powdered," vitreous, and porcelainous. When freshly fused, it ap- pears in colorless or faintly yellow, translucent, vitreous masses, having no visible crystalline structure. Shortly, however, these masses become opaque upon the surface, and present the appearance of porcelain. This change slowly progresses toward the center of the mass, which, however, remains vitreous for a long time. When arsenic trioxide is sublimed, if the vapors are condensed upon a cool surface, it is deposited in the form of brilliant octahedral crystals, which are larger and more perfect the nearer the temperature of the condensing surface is to 180. When sublimed under slightly in- creased pressure, or in an atmosphere of S0 2 , right rhombic prisms occur among the octahedra. It is therefore dimorphous. The crystal- line variety may be converted into the vitreous, by keeping it for some time at a temperature near its point of volatilization. Although As 2 3 is heavier than water, when thrown upon that liquid a large part of the crystalline powder floats, and a part of that which sinks at first subsequently rises. This is due to adhesion of air to the particles of the solid. The same phenomenon renders the ARSENIC 113 solution of As 2 3 in water slow and irregular. The vitreous variety is more- readily soluble than the crystalline. The taste of arsenic trioxide in solution is very faint, at first sweetish, afterward very slightly metallic. The solid is almost tasteless. It is odorless. In aqueous solution .it has a faintly acid reaction. The sp. gr. of the vitreous variety is 3.785 ; that of the crystalline, 3.689. Chemical. Its solutions are acid in reaction, and probably contain the true arsenous acid, H 3 As0 3 . They are neutralized by bases, with formation of arsenites. Solutions of sodium, or potassium hydroxide, or carbonate dissolve it, with formation of the corresponding arsenite. It is readily reduced, with separation of As, when heated with hydro- gen, carbon, and potassium cyanide, and at lower temperatures by more active reducing agents. Oxidizing agents, such as HN0 3 , the chlorine oxyacids, chromic acid, convert it into arsenic pentoxide or arsenic acid. Its solution, acidulated with HC1 and boiled in presence of copper, deposits on the metal a gray film, composed of an alloy of Cu and As. Arsenic Pentoxide Arsenic anhydride Arsenic oxide As 2 5 230 is obtained by heating arsenic acid to redness. It is a white, amorphous solid, which, when exposed to the air, slowly absorbs moisture. It is fusible at a dull red heat, and at a slightly higher temperature decomposes to As 2 3 and 2 . It dissolves slowly in H 2 0, forming arsenic acid, H 3 As0 4 . Arsenic Acids. The oxyacids of arsenic form a series, corre- sponding to that of the oxyacids of phosphorus, except that the hypo- arsenous and hypoarsenic acids are unknown, and pyro- and metar- senous acids are known in their salts : /O H /O H Arsenic acid: 0=zAs O H Arsenous acid: O=As H \0 H \H /O H /A O H O=As H /AS Q TT V Pyroarsenous acid: O Pyroarsenic acid: V* V A in f \ \O H \ As __ H 0=As O H Metarsenous acid: 0=As O H /O H Metarsenic acid: O=As=0 Arsenous Acid. H 3 As0 3 126 exists in aqueous solutions of the trioxide, although it has not been separated. Corresponding to it are important salts, called arsenites, which have the general for- mula HM' 2 As0 3 , HM"As0 3 , H 4 M"(As0 3 ) 2 . Pyro- and metarsenous acids are only known in combination. Arsenic Acid Orthoarsenic acid H 3 As0 4 142 is obtained by oxidizing As 2 3 with HN0 3 in the presence of H 2 : As 2 3 +2H 2 0+2HN0 3 =N 2 3 +2H 3 As0 4 114 TEXT-BOOK OF CHEMISTRY A similar oxidation is also effected by Cl, aqua regia, and other oxidants. A syrupy, colorless, strongly acid solution is thus obtained, which, at 15, becomes semi-solid, from the formation of transparaent crys- tals, containing 1 Aq. These crystals, which are very soluble and deliquescent, lose their Aq at 100, and form a white, pasty mass, composed of minute white, anhydrous needles. At higher tempera- tures it is converted into H 4 As 2 7 , HAs0 3 , and As 2 5 . In presence of nascent H it is decomposed into H 2 and AsH 3 . It is reducible to H 3 As0 3 by S0 2 . Like phosphoric acid, arsenic acid is tribasic; and the arsenates resemble the phosphates in composition, and in many of their chemi- cal and physical properties. Metarsenic Acid HAs0 3 124. At 200 -206 H 4 As 2 7 grad- ually loses H 2 O to form metarsenic acid: H 4 As 2 7 =2HAs0 3 +H 2 0. It forms white, pearly crystals, which dissolve readily in H 2 0, with regeneration of H 3 As0 4 . It is monobasic. Compounds of Arsenic and Sulphur. Arsenic Bisulphide Red sulphide of arsenic Realgar Red orpiment As 2 S 2 214 occurs in nature, in translucent, ruby-red crystals. It is also prepared by heating a mixture of As 2 3 and S. As so obtained it appears in brick-red masses. It is fusible, insoluble in H 2 0, but soluble in solutions of the alkaline sulphides, and in boiling solution of potassium hydroxide. Arsenic Trisulphide. Orpiment Yellow sulphide of arsenic- King's yellow As 2 S 3 246 occurs in nature in brilliant golden yellow flakes. Obtained by passing H 2 S through an acid solution of As 2 3 ; or by heating a mixture of As and S, or of As 2 3 and S in equivalent proportions. When formed by precipitation, it is a lemon-yellow powder, or in orange-yellow, crystalline masses, when prepared by sublimation. Almost insoluble in cold H 2 0, but sufficiently soluble in hot H 2 to communicate to it a distinct yellow color. By continued boiling with H 2 it is decomposed into H 2 S and As 2 3 . Insoluble in dilute HC1 ; but readily soluble in solutions of the alkaline hydroxides, carbonates, and sulphides. It volatilizes when heated. Nitric acid oxidizes it, forming H 3 As0 4 and H 2 S0 4 . A mixture of HC1 and potassium chlorate has the same effect. It corresponds in constitution to As 2 3 , and like it, may be regarded as an an- hydride, for although thioarsenous acid, H 3 AsS 3 , has not been sepa- rated, the thioarsenites, pyro- and meta-thioarsenites are well-char- acterized compounds. Arsenic Pentasulphide As 2 S r , 310 is formed by fusing a mix- ture of As 2 S 3 and S in proper proportions, and, by the prolonged action of H,S, at low temperatures, upon solutions of the arsenates. It is a yellow, fusible solid, capable of sublimation in absence of ARSENIC 115 air. There* exist well-defined thioarsenates, pyro- and meta-thio- arsenates. Action of Arsenical Compounds Upon the Animal Economy. The poison is usually taken by the mouth, but it has also been introduced by other channels; the skin, either uninjured or abraded, the rectum, vagina, and male urethra. The forms in which it has been taken are : ( 1 ) Elementary arsenic, which is not poisonous so long as it remains such. In contact with water, or with the saliva, however, it is converted into an oxide, which is then dissolved, and, being capable of absorption, produces the characteristic effects of the arsenical compounds. Certain fly-papers and fly-poisons contain As, a portion of which has been oxidized by the action of air and moisture. (2) Hydrogen arsenide, the most actively poisonous of the inorganic compounds of arsenic, has been the cause of several accidental deaths; death has followed the inhalation of hydrogen, made from zinc and sulphuric acid contaminated with arsenic. (3) Arsenic trioxide is the compound most frequently used by criminals. It has been given by every channel of entrance to the circulation; and if given in large quantity, and undissolved, it may be found in the stomach after death, in the form of eight-sided crystals, more or less worn by the action of the solvents with which it has come in contact. (4) Potassium arsenite, the active substance in " Fowler's solution," has produced but few cases of fatal poisoning. (5) Sodium arsenite is sometimes used to clean metal vessels; a practice which has resulted in death or serious illness. (6) Arsenic acid and arsenates- The acid itself has, so far as we know, been directly fatal to no one. But the cases of death and illness which have been put to the account of the red aniline dyes, are not due to them directly, but to arsenical residues remaining in them as the result of defective processes of manufacture. ( 7 ) Sulphides of arsenic. Poisoning by these is generally due to the use of orpiment, introduced into articles of food as a coloring matter, by a combination of fraud and stupidity, in mistake for turmeric. (8) The arsenical greens. Scheele's green, or cupric arsenite, and Schweinfurth green, or cupric aceto-metarsenite (the latter commonly known in the United States as Paris green, a name applied in Europe to one of the aniline pigments ) . The arsenical pigments may also produce disastrous results by "accident;" by being incorporated in ornamental pieces of confectionery; by being used in the coloring of textile fabrics, from which they may be easily rubbed off; from their use for the destruction of insects, and by being used in the manufacture of wall-paper. Many instances of chronic or subacute arsenical poisoning have resulted from inhabiting rooms hung with paper whose whites, reds, or greens were produced by arsenical pigments. From such paper the poison is dissemi- nated in the atmosphere of the room in two ways: either as an impalpable powder, mechanically detached from the paper and floating in the air, or by their decomposition, and the consequent diffusion of volatile arsenical com- pounds in the air. The treatment in acute arsenical poisoning is the same, whatever may be the form in which the poison has been taken, if it has been taken by the mouth. The first indication is the removal of any unabsorbed poison from the alimentary canal. If vomiting has not occurred from the effects of the toxic, it should be induced by the administration of apomorphine, or zinc sulphate, or by mechani- cal means. When the stomach has been emptied, the chemical antidote is to be administered, with a view to the transformation, in the stomach, of any re- maining arsenical compound into the insoluble, and therefore innocuous, ferrous arsenate. The U. S. P. gives an " arsenic antidote," ferri hydroxidum cum magnesii oxido (ferric hydroxide with magnesium oxide): "Mix 40 cc. of 116 TEXT-BOOK OF CHEMISTRY solution of ferric sulphate with 125 cc. of water, and keep the liquid in a large, well-stoppered bottle. Rub 10 gm. magnesium oxide with cold water to a smooth and thin mixture, transfer this to a bottle capable of holding about 1000 cc., fill it with water to about three-fourths of its capacity, and keep it tightly stoppered. When the preparation is wanted for use, shake the mag- nesium oxide mixture until of a thin, creamy consistence, slowly add to it the diluted solution of ferric sulphate, and shake them together until a uniformly smooth mixture results." The dose is about four fluid ounces. Dialyzed iron may be given when the antidote is not obtainable. Precautions to be taken by the Physician in cases of Suspected Poisoning. In a case in which, from the symptoms, the physician suspects poisoning by any substance, he should himself test the urine or feces, or both, and govern his treatment and his actions toward the patient, and those surrounding the patient, by the results of his examination. Should the case terminate fatally, he should at once communicate his suspicions to the prosecuting officer, and require a post-mortem investigation, which should, if at all possible, be con- ducted in the presence of the chemist who is to conduct the analysis. Cases frequently arise in which it is impossible to bring the chemist upon the ground in time for the autopsy. In such cases the physician should remem- ber that that portion of the poison remaining in the alimentary tract (we are speaking of true poisons) is but the residue of the dose in excess of that which has been necessary to produce death; and, if the processes of elimination have been active, there may remain no trace of the poison in the alimentary canal, while it still may be detectable in the deeper-seated organs. The poison may also have been administered by another channel than the mouth, in which event it may not reach the stomach. For these reasons it is not sufficient to send the stomach alone for analysis. The chemist should also receive the entire intestinal canal, the liver, the spleen, one or both kidneys, a piece of muscular tissue from the leg, the brain, and any urine that may remain in the bladder. The intestinal canal should be removed and sent to the chemist without having been opened, and with liga- tures, enclosing the contents, at the two ends of the stomach and at the lower end of the intestine. The brain and alimentary canal are to be placed in separate jars, and the other viscera in another jar together; the urine in a vial by itself. All of these vessels are to be new and clean, and are to be closed by new corks, or by glass stoppers, or covers ( not zinc screw-caps ) , which are then coated with paraffin (not sealing-wax), and so fastened with strings and seals, that it is impossible to open the vessels without cutting the strings or breaking the seals. Any vomited matters are to be preserved. If the physician fails to observe these precautions, he has probably made the breach in the evidence through which the criminal will escape, and has at the outset de- feated the aim of the analysis. Analytical Characters of the Arsenical Compounds. ARSENOUS COMPOUNDS. (1) H 2 S, a yellow color in neutral or alkaline liquids; a yellow ppt. in acid liquids. The ppt. dissolves in solutions of the alkaline hydroxides, carbonates and sulphydrates ; but is scarcely affected by HC1. Hot HN0 3 decomposes it. (2) AgN0 3 , in the presence of a little NH 4 OH, gives a yellow ppt. This test is best applied by placing the neutral arsenical solu- tion in a porcelain capsule, adding neutral solution of AgN0 3 , and blowing upon it over the stopper of the NH 4 OH bottle, moistened with that reagent. ARSENIC 117 (3) CuS0 4 under the same conditions as in (2) gives a yellowish green ppt. (4) Reinsch Test. The suspected liquid is acidulated with one- sixth its bulk of HC1. Strips of electrotype copper are immersed in the liquid, which is boiled. In the presence of an arsenous com- pound, a gray or bluish deposit is formed upon the Cu. A similar deposit is produced by other substances (S, Au, Pt, Bi, Sb, Hg). To complete the test the Cu is removed, washed, and dried between folds of filter paper, without removing the deposit. The copper, with its adherent film, is rolled into a cylinder, and introduced into a dry piece of Bohemian tubing, about one-fourth inch in diameter and six inches long, which is held at the angle shown in Fig. 13 and heated at the point containing the copper. If the deposit consists of arsenic, a white deposit is formed at a, which contains brilliant specks, and, when examined with a magnifier, is found to consist entirely of minute octahedral crystals (Fig. 14). FIG. 13. FIG. 14. If the stain upon the copper, formed in the first part of the reac- tion, has been caused by S, Au, Pt, or Bi, no sublimate is produced during the subsequent heating in the glass tube, as the product of oxidation of sulphur is gaseous, Au and Pt are neither oxidized nor volatilized, and Bi is oxidized, but its oxide is not volatile. Subli- mates are, however, formed from deposits caused by Sb or Hg, which differ from that produced by arsenic in the following respects : That from Sb consists of Sb 2 3 , which is entirely, or almost entirely, amorphous, or granular, possibly containing one or two octahedral crystals, whose borders are darker than those of As 2 3 . The sub- limate from Hg consists of microscopic globules of the liquid metal. Reinsch 's reaction is, therefore, a test for antimony and mercury, as well as for arsenic. The advantages of the Reinsch test are : it may be applied in the presence of organic matter, to the urine for instance ; it is easily con- ducted; and its positive results are not misleading, if the test is carried to completion. These advantages render it the most suitable method for the physician to use, during the life of the patient. It 118 TEXT-BOOK OF CHEMISTRY should not be used after death by the physician, as by it copper is introduced into the substances under examination, which may sub- sequently interfere seriously with the analysis. The purity of the Cu and HC1 must be proved by a blank testing before use. Reinsch's test is not as delicate as Marsh's, and it only reacts slowly and im- perfectly when the arsenic is in the higher stage of oxidation, or in presence of oxidizing agents. (5) Marsh's test is based upon the formation of AsH 3 when a reducible compound of arsenic is in presence of nascent H ; and the subsequent decomposition of the arsenical gas by heat, with separa- tion of elementary arsenic. The apparatus used (Fig. 15) consists of a glass generating ves- sel, a, of about 150 cc. capacity, provided with a funnel-tube having a stop-cock, and a lateral outlet, either fitted in with a cork, or, better, ground in. The lateral outlet is connected with a tube, 6, filled with fragments of calcium chloride ; which in turn connects with the Bohemian glass tube cc, which should be about 0.5 cent, in diameter, FIG. 15. and about 80 cent. long. The tube is protected by a tube of wire gauze, within which it is adjusted in the furnace as shown in the figure. The other end of cc is bent downward, and dips into a solu- tion of silver nitrate in the test-tube, d. The vessel a is first charged with about 25 grams of an alloy of pure granulated zinc, with a small quantity of platinum. The apparatus is then connected gas-tight, and the funnel tube about half filled with H 2 S0 4 , diluted with an equal bulk of H 2 0, and cooled. By opening the stopcock, the acid is brought in contact with the zinc in small quantities, in such a manner that during the entire testing bubbles of gas pass through d at the rate of 60-80 per minute. After fifteen minutes the burner is lighted, and the heating continued, during evolution of gas from zinc and H 2 S0 4 , for an hour. At the end of that time, if no stain has formed in cc beyond the burner, the zinc and acid may be considered to be pure, and the suspected solu- ARSENIC 119 tion, which must have been previously freed from organic matter and from tin and antimony, is introduced slowly through the funnel-tube. If arsenic is present in the substance examined, a hair-brown or gray deposit is formed in the cool part of cc beyond the heated part. At the same time the contents of d are darkened if the amount of As present is so great that all the AsH 3 produced is not decomposed in the heated portion of cc. To distinguish the stains produced by arsenical compounds from the similar ones produced by antimony the following differences are noted : The Antimonial Stain. The Arsenical Stain. 1. Is farther removed from the heated portion of the tube, and, if small in quantity, is double the first hair-brown, the second steel-gray. 2. Volatilizes readily when heated in an atmosphere of hydrogen, being de- posited farther along in the tube. The escaping gas has the odor of garlic. 3. When cautiously heated in a cur- rent of oxygen, brilliant, white, octahe- dral crystals of arsenic trioxide are deposited farther along in the tube. 4. Instantly soluble in solution of sodium hypochlorite. 5. Slowly dissolved by solution of ammonium sulphydrate; more rapidly when warmed. 6. The solution obtained in (5) leaves, on evaporation over the water- bath, a bright yellow residue. 7. The residue obtained in (6) is soluble in aqua ammonise, but insoluble in hydrochloric acid. 8. Is soluble in warm nitric acid; the solution on evaporation yields a white residue, which turns brick-red when moistened with silver nitrate solution. 9. Is not dissolved by a solution of stannous chloride. 1. Is quite near the heated portion of the tube. A second stain is also usually formed in front of the heated part of the tube. 2. Requires a much higher tempera- ture for its volatilization; fuses before volatilizing. Escaping gas has no alliaceous odor. 3. No crystals formed by heating in oxygen, but an amorphous, white sublimate (see p. 000). 4. Insoluble in solution of sodium hypochlorite. 5. Dissolves quickly in solution of ammonium sulphydrate. 6. The solution obtained in (5) leaves, on evaporation over the water- bath, an orange-red residue. 7. The residue obtained in (6) is insoluble in aqua ammoniae, but soluble in hydrochloric acid. 8. Is soluble in warm nitric acid; the solution on evaporation yields a white residue, which is not colored when moistened with silver nitrate solution. 0. Dissolves slowly in solution of stannous chloride. The silver solution in d is tested for arsenous acid, by floating upon its surface a layer of diluted NH 4 OH solution, which, in the presence of arsenic, produces a yellow (not brown) band, at the point of junction of the two liquids. In place of bending the tube c downward, it may be bent upward and drawn out to a fine opening. If the escaping gas is then ignited, 120 TEXT-BOOK OF CHEMISTRY the heating of the tube being discontinued, a white deposit of As 2 3 may be collected on a glass surface held above the flame ; or a brown deposit of elementary As upon a cold (porcelain) surface heir 1 in the flame. In place of generating nascent hydrogen by the action of Zn on H 2 S0 4 , it may be produced by the decomposition of acidulated H 2 by the battery, in a Marsh apparatus especially modified for that purpose. In another modification of the Marsh test the AsH 3 is decomposed, not by passage through a red-hot tube, but by passing through a tube traversed by the spark from an induction coil. ARSENIC COMPOUNDS. (1) H 2 S does not form a ppt. in neutral or alkaline solutions. In acid solutions a yellow ppt., consisting either of As 2 S 3 or As 2 S.,, or a mixture of the sulphides with free S, is formed only after prolonged passage of H 2 S at the ordinary tempera- ture, more rapidly at about 70 . (2) AgN0 3 , under the same conditions as with the arsenous com- pounds, produces a brick-red ppt. of silver arsenate. (3) CuS0 4 under like circumstances produces a bluish green ppt. Arsenic compounds behave like arsenous compounds with Marsh's test. ANTIMONY. Symbol=$\) (Latin: stibium) Atomic weight=12Q (Inter- national 120.2) Molecular weight ( ?) Sp. #r.=6.175. Occurrence. Free in small quantity; principally in the trisul- phide, Sb,S 3 . Preparation. The native sulphide (black or crude antimony) is roasted, and then reduced by heating with charcoal. Properties. Physical. A bluish gray, brittle solid, having a metallic luster; readily crystallizable ; tasteless and odorless; vola- tilizes at a red heat, and may be distilled in an atmosphere of H. Chemical. Is not altered by dry or moist air at ordinary tempera- tures. When sufficiently heated in air, it burns, with formation of Sb 2 3 , as a white, crystalline solid. It also combines directly with Cl, Br, I, S, and many metallic elements. It combines with H under the same circumstances as does As. Cold dilute H 2 S0 4 does not affect it; the hot concentrated acid forms with it antimonyl sulphate (SbO) 2 S0 4 and S0 2 . Hot HC1 dissolves it, when finely divided, with evolution of H. It is readily oxidized by HNO. { . with formation of H 3 Sb0 4 or Sb,0 4 . Aqua regia dissolves it as SbCl 3 , or SbCl 5 . Solu- tions of the alkaline hydroxides do not act on it. The element does not form salts with the oxyacids. There are, how- ever, compounds, formed by the substitution of the group antimonyl (SbO), for the basic hydrogen of those acids. (Sec Tartar emetic.) ANTIMONY 121 It enters into the composition of type metal, anti-friction metals, and britannia metal. Hydrogen Antimonide Stibine Antimoniuretted hydrogen SbH 3 123. It is produced, mixed with H, when a reducible com- pound of Sb is in presence of nascent H. It is obtained in larger amount by decomposing an alloy of 400 parts of a 2% sodium amalgam, and 8 parts of freshly reduced, and dried Sb, by H 2 0, in a current of C0 2 . It is a colorless, odorless, combustible gas, subject to the same decompositions as AsH 3 ; from which it differs in being by no means as poisonous, and in its action upon silver nitrate solution. The arsenical gas acts upon the silver salt according to the equation : 6AgN0 3 +2AsH 3 +H 2 =Ag 2 +2Ag 2 HAs0 3 +6HN0 2 and the precipitate formed is elementary silver, while Ag 2 HAs0 3 remains in the solution. In the case of SbH 3 the reaction is 3AgN0 3 +SbH 3 =3HN0 3 +SbAg 3 , all of the Sb being precipitated in the black silver antimonide. Chlorides of Antimony. Antimony Trichloride Butter of antimony SbCl 3 226.5 is obtained by passing dry Cl over an excess of Sb 2 S 3 ; by dis- solving Sb 2 S 3 in HC1 : Sb 2 S 3 -f6HCl=3H 2 S+2SbCl s Or by distilling mixtures, either of Sb 2 S 3 and mercuric chloride, or of Sb and mercuric chloride. At low temperatures it is a solid, crystalline body; at the ordinary tem- perature a yellow, semi-solid mass, resembling butter; at 73.2, it fuses to a yellow, oily liquid, which boils at 223. It absorbs moisture from air, and is soluble in a small quantity of H 2 O; with a larger quantity it is decomposed, with precipitation of a white powder, powder of Algaroth, whose composition is SbOCl if cold H 2 O be used, and Sb 4 5 Cl 2 if the H 2 O be boiling. In H 2 containing 15 per cent, or more HC1, SbCl 3 is soluble without decomposition. Antimony Pentachloride SbCl 5 297.5 is formed by the action of Cl in excess, upon Sb or SbCl 3 : SbCl 3 +Cl 2 =SbCl 5 It is a fuming, colorless liquid. With a small quantity of H 2 0, and evaporation over H 2 S0 4 , it forms a hydrate, SbCl 5 4H 2 O, which appears in trans- parent, deliquescent crystals. With more H 2 0, a crystalline oxychloride, SbOCl 3 , is formed; and with still greater quantity, a white precipitate of orthoantimonic acid, H 3 Sb0 4 . Compounds of Antimony and Oxygen. Three are known, Sb 2 3 , Sb 2 4 and Sb 2 5 . Antimony Trioxide Antimonous anhydride Oxide of antimony Sb 2 3 288 occurs in nature ; and is prepared artificially by heat- ing Sb in air, or by decomposing the oxychloride : 2SbOCl+Na 2 C0 3 =2NaCl-(-C0 2 +Sb 2 03 122 TEXT-BOOK OF CHEMISTRY It crystallizes in prisms or in octahedra, and is isodimorphous with As 2 3 , or is an amorphous, insoluble, tasteless, odorless powder ; white at ordinary temperatures, but yellow when heated. It fuses readily, and may be distilled in absence of oxygen. Heated in air, it burns like tinder, and is converted into Sb 2 4 . It is reduced, with separation of Sb, when heated with charcoal, or in H. It is already oxidized by HN0 3 , or potassium perman- ganate. It dissolves in HC1 as SbCl 3 ; in Nordhausen sulphuric acid, from which solution brilliant crystalline plates of antimonyl pyrosul- phate, (SbO) 2 S 2 7 , separate; and in solutions of tartaric acid, and of hydropotassic tartrate (see Tartar emetic). Boiling solutions of alka- line hydroxides convert it into antirnonic acid. Antimony Pentoxide Antimonic anhydride Sb 2 5 320 is ob- tained by heating metantimonic acid to dull redness. It is an amor- phous, tasteless, odorless, pale lemon-yellow colored solid; very spar- ingly soluble in water and in acids. At a red heat it is decomposed into Sb 2 4 and 0. Antimony Acids. The normal antimonous acid, H 3 SbO 3 , corresponding to H 3 PO 3 , is unknown; but the series of antimonic acids: ortho, H 3 SbO 4 ; pyro, H 4 Sb 2 O T ; and meta, HSbO 3 , is complete, either in the form of salts, or in that of the free acids. There also exists, in its sodium salt, a derivative of the lacking antimonous acid: metantimonous acid, HSb0 2 . Sulphides of Antimony. Antimony Trisulphide Black anti- mony Sb 2 S 3 336 is the chief ore of antimony; and is formed when H 2 S is passed through a solution of tartar emetic. The native sulphide is a steel-gray, crystalline solid ; the artificial product, an orange-red, or brownish-red, amorphous powder. The crude antimony of commerce is in conical loaves, prepared by simple fusion of the native sulphide. It is soft, fusible, readily pulverized, and has a bright metallic luster. Heated in air, it is decomposed into S0 2 and a brown, vitreous, more or less transparent mass, composed of varying proportions of oxide and oxysulphides, known as crocus, or liver, or glass of anti- mony. Sb.,S 3 is an anhydride, corresponding to which are salts known as thioantimonites, having the general formula M' 2 HSbS 3 . If an excess of Sb 2 S 3 is boiled with a solution of potash or soda, a liquid is obtained, which contains an alkaline thioantimonite, and an excess of Sb 2 S 3 . If this solution is filtered and allowed to cool, a brown, voluminous, amorphous precipitate separates, which consists of anti- mony trisulphide and trioxide, potassium or sodium sulphide, and alkaline thioantimonite in varying proportions; and is known as Kermes mineral. Antimony Pentasulphide Sb,S 5 400 is obtained by decom- posing an alkaline thioantimonate by an acid. It is a dark orange- red, amorphous powder, readily soluble in solutions of the alkalies, and alkaline sulphides, with which it forms thioantimonates. BORON 123 Action of Antimony Compounds on the Economy. The compounds of antimony are poisonous, and act with greater or less energy as they are more or less soluble. The compound which is most frequently the cause of antimonial poisoning is tartar emetic (q. v.) , which has caused death in a quantity of three grains, in divided doses, although recovery has followed the ingestion of half an ounce in several instances. Indeed, the chances of recovery seem to be better with large, than with small doses, probably owing to the more rapid and com- plete removal of the poison by vomiting with large doses. Antimonials have been sometimes criminally administered in small and repeated doses, the victim dying of exhaustion. In such a case an examination of the urine will reveal the cause of the trouble. If vomiting has not occurred in cases of acute antimonial poisoning it should be provoked by apomorphine or warm water, or the stomach should be washed out. Tannin in some form (decoction of oak bark, cinchona, nutgalls, tea) should then be given, with a view to rendering any remaining poison insoluble. Medicinal antimonials are very liable to contamination with arsenic. Analytical Characters of Antimonial Compounds. (1) With HoS in acid solution: an orange-red ppt., soluble in NH 4 HS and in hot HC1. (2) A strip of bright copper, suspended in a boiling solution of an Sb compound, acidulated with HC1, is coated with a blue-gray deposit. This deposit when dried (on the copper), and heated in a tube open at both ends yields a white, amorphous sublimate (see Reinsch's test, p. 117). (3) Antimonial compounds yield a deposit by Marsh's test, sim- ilar to that obtained with arsenical compounds, but differing in the particulars given above (see Marsh's test, pp. 118, 119). IV. BORON GROUP. BORON. =B Atomic weight =11. (International^ll.Q) Molecu- lar weight=22. Boron occurs in nature in the borates of Ca, Mg, and Na, princi- pally as sodium pyroborate (borax). It constitutes a group by itself; it is trivalent in all its compounds; it forms but one oxide, which is the anhydride of a tribasic acid ; and it forms no compound with H. It is separable in two allotropic modifications. Amorphous boron is prepared by decomposition of the oxide, by heating with metallic potassium or sodium: B 2 3 +3Na 2 =3Na 2 0+B 2 It is a greenish brown powder; sparingly soluble in H 2 0; in- fusible; and capable of direct union with Cl, Br, 0, S, and N. 124 TEXT-BOOK OF CHEMISTRY Crystallized boron is produced when the oxide, chloride or fluoride is reduced by Al. It crystallizes in quadratic prisms; more or less transparent, and varying in color from a faint yellow to deep garnet- red ; very hard ; sp. gr. 2.68. It burns when strongly heated in 0, and readily in Cl; it also combines with N, which it is capable of re- moving from NH 3 at a high temperature. Boron Trioxide. Boric or boracic anhydride B.,0 3 70 is ob- tained by heating boric acid to redness in a platinum vessel. It is a transparent, glass-like mass, used in blowpipe analysis under the name vitreous boric acid. Boric Acids. Boric Acid Boracic acid Orthoboric acid Acidum boricum (U. S. P.) H 3 B0 3 62 occurs in nature; and is prepared by slowly decomposing a boiling, concentrated solution of borax, with an excess of H 2 S0 4 , and allowing the acid to crystallize : Na 2 B 4 7 +H 2 S0 4 +5H 2 0=Na 2 S0 4 +4H 3 B0 3 It forms brilliant, crystalline plates, unctuous to the touch ; odor- less ; slightly bitter ; soluble in 34 parts H 2 at 10 ; soluble in alcohol. Its solution reddens litmus, but turns turmeric paper brown. When its aqueous solution is distilled, a portion of the acid passes over. Boric acid readily forms esters with the alcohols. When heated with ethylic alcohol, ethyl borate is formed, which burns with a green flame. Heated with glycerol, a soluble, neutral ester is formed, known as boroglyceride, and used as an antiseptic. If H 3 B0 3 be heated for some time at 80, it loses H 2 and is converted into metaboric acid, HB0 2 . If maintained at 100 for several days, it loses a further quantity of H 2 0, and is converted into tetraboric or pyroboric acid, H 2 B 4 7 , whose sodium salt is borax. (See p. 154.) V. CARBON GROUP. CARBON SILICON. The elements of this group are quadrivalent. The saturated oxide of each is the anhydride of a dibasic acid. They are both combustible, and each occurs in three allotropic forms. CARBON. Symbolic Atomic weight=l2 (International 12.005) Molec- ular weight=24:. Occurrence. Free in its three allotropic forms: The diamond in octahedral crystals; in alluvial sand, clay, sandstone, and con- glomerate; graphite, in amorphous or imperfectly crystalline forms; amorphous, in the different varieties of anthracite and bituminous CARBON 125 coal, jet, etc. In combination, it is very widely distributed in the so-called organic substances. Properties. Diamond. The crystals of diamond, which is al- most pure carbon, are usually colorless or yellowish, but may be blue, green, pink, brown or black. It is the hardest substance known, and the one which refracts light the most strongly. Its index of refraction is 2.47 to 2.75. It is brittle ; a bad conductor of heat and of electricity; sp. gr. 3.50 to 3.55. When very strongly heated in air it burns, without blackening, to carbon dioxide. Graphite is a form of carbon almost as pure as the diamond, capable of crystallizing in hexagonal plates ; sp. gr. 2.2 ; dark gray in color; opaque; soft enough to be scratched by the nail; and a good conductor of electricity. It is also known as black lead or plum- bago. It has been obtained artificially, by allowing molten cast-iron, containing an excess of carbon, to cool slowly, and dissolving the iron in HC1. When oxidized with potassium chlorate and nitric acid it yields graphitic acid, C n H 4 5 . Amorphous carbon is met with in a great variety of forms, nat- ural and artificial, in all of which it is black; sp. gr. 1.6-2.0; more or less porous ; and a conductor of electricity. Anthracite coal is hard and dense; it does not flame when burn- ing; is difficult to kindle, but gives great heat with a suitable draught. It contains 80-90 per cent, of carbon. Bituminous coal differs from anthracite in that, when burning, it gives off gases, which produce a flame. Some varieties are quite soft, while others, such as jet, are hard enough to assume a high polish. It is usually compact in texture, and very frequently contains impressions of leaves, ^and other parts of plants. It contains about 75 per cent, of carbon. Charcoal, wood charcoal, carbo ligni, (U. S. P.) is obtained by burning woody fiber, with an insufficient supply of air. It is brittle and sonorous ; has the form of the wood from which it was obtained, and retains all the mineral matter present in the woody tissue. Its sp. gr. is about 1.57. It has the power of condensing within its pores odorous substances and large quantities of gases; 90 volumes of ammonia, 55 of hydrogen sulphide, 9.25 of oxygen. This property is taken advantage of in a variety of ways. Its power of absorbing odorous bodies renders it valuable as a disinfecting and filtering agent, and in the prevention of putrefaction and fermentation of certain liquids. The efficacy of charcoal as a filtering material is due also, in a great measure, to the oxidizing action of the oxygen condensed in its pores ; indeed, if charcoal is boiled with dilute HC1, dried, and heated to redness, the oxidizing action of the oxygen, which it thus condenses, is very energetic. When small strips of wood are heated to redness in a current of vapor of carbon disulphide, or of hydrocarbons, metallic carbon is 126 TEXT-BOOK OF CHEMISTRY produced. This is very sonorous, and is a very good conductor of heat and of electricity. The filaments in incandescent electric lamps are prepared from vegetable parchment or bamboo fiber in a similar manner. Lamp-black is obtained by incomplete combustion of some resi- nous or tarry substance, or natural gas, the smoke or soot from which is directed into suitable condensing chambers. It is a light amor- phous powder, and contains a notable quantity of oily and tarry material, from which it may be freed by heating in a covered vessel. It is used in the manufacture of printer's ink. Coke is the substance remaining in gas retorts, after the distil- lation of bituminous coal, in the manufacture of illuminating gas. It is a hard, grayish substance, usually very porous, dense, and sonorous. When iron retorts are used, a portion of the gaseous products are decomposed by contact with the hot iron surface, upon which there is then deposited a layer of very hard, compact, grayish carbon, which is a good conductor of electricity. Animal charcoal is obtained by calcining animal matters in closed vessels. If prepared from bones it is known as bone-black, carbo animalis; if from ivory, ivory black. The latter is used as a pig- ment, the former as a decolorizing agent. Bones yield about 60 per cent, of bone-black, which contains, besides carbon, nitrogen and the phosphates and other mineral substances of the bones. It pos- sesses in a remarkable degree the power of absorbing coloring mat- ters. When its decolorizing power is lost by saturation with pig- mentary bodies, it may be restored, although not completely, by cal- cination. For certain purposes purified animal charcoal, i.e., freed from mineral matter, carbo animalis purificatus, is required, and is obtained by extracting the commercial article with HC1, and wash- ing it thoroughly. Its decolorizing power is diminished by this treatment. Animal charcoal has the power of removing from a solu- tion certain crystalline substances, notably the alkaloids, and a method has been suggested for separating these bodies from organic mixtures by its use. All forms of carbon are insoluble in any known liquid. Chemical. All forms of C combine with at high temperatures, with light and heat. The product of the union is carbon dioxide if the supply of air or is sufficient ; but if is present in limited quan- tity, carbon monoxide is formed. The affinity of C for renders it a valuable reducing agent. Many metallic oxides are reduced, when heated with C, and steam is decomposed when passed over red-hot C : H 2 0-f C=CO-j-H 2 . At elevated temperatures C also combines di- rectly with S, to form carbon disulphide. With H, carbon also com- bines directly, under the influence of the voltaic arc. For Compounds of Carbon, see page 191. SILICON 127 SILICON. Symbol ^>\ Atomic weight=2S (International, 28.3) Molecu- lar weight=56. Also known as silicium; occurs in three allotropic forms: Amor- phous silicon, formed when silicon chloride is passed over heated K or Na, is a dark brown powder, heavier than water. When heated in air, it burns with a bright flame to the dioxide. It dissolves in potash and in hydrofluoric acid, but is not attacked by other acids. Graphi- toid silicon is obtained by fusing potassium fluosilicate with alumin- ium. It forms hexagonal plates, of sp. gr. 2.49, which do not burn when heated to whiteness in 0, but may be oxidized at that tem- perature, by a mixture of potassium chlorate and nitrate. It dis- solves slowly in alkaline solutions, but not in acids. Crystallized silicon, corresponding to the diamond, forms crystalline needles, which are only attacked by a mixture of nitric and hydrofluoric acids. Silicon, although closely related to C, exists in nature in compara- tively few compounds ; it occurs abundantly, however, as silicon dioxide and in the form of silicates. Silicon Chloride SiCl 4 170 a colorless, volatile liquid, having an irritat- ing odor; sp. gr. 1.52; boils at 59; formed when Si is heated to redness in Cl. Silicon Dioxide Silica Silicic Oxide Silicic anhydride Silex Si0 2 60 is the most important of the compounds of silicon. It exists in nature in the different varieties of quartz, and in the rocks and sands containing that mineral, in agate, carnelian, flint, etc. Its purest native form is rock crystal. It may be obtained by heating a solution of sodium silicate with hydrochloric acid: Na 2 Si0 3 -f 2HCl=2NaCl-|-H 2 O-f-SiO 2 . Its hydrates occur in the opal, and in solution in natural waters. When crystallized, it is fusible with difficulty. When heated to redness with the alkaline carbonates, it forms silicates, which solidify to glass-like masses, on cooling. It unites with H 2 O to form a number of acid hydrates. The normal hydrate, H 4 SiO 4 , has not been isolated, although it probably exists in the solution obtained by adding an excess of HC1 to a solution of sodium silicate. A gelatinous hydrate, soluble in water and in acids and alkalies, is obtained by adding a small quantity of HC1 to a concentrated solution of sodium silicate. Hydrofluosilicic Acid H,SiF 6 144 is obtained in solution by passing the gas disengaged by gently heating a mixture of equal parts of fluorspar and pounded glass and 6 pts. H 2 S0 4 through water; the disengagement tube being protected from moisture by a layer of mercury. It is used in analysis as a test for K and Na. Silicon Carbide SiC is produced by the action of a powerful electric current upon a mixture of coke and aluminium silicate. It forms blue crystals, is very hard, and is used as a polishing agent under the name Carborundum. 128 TEXT-BOOK OF CHEMISTRY VI. VANADIUM GROUP. VANADIUM COLUMBIUM TANTALUM. The elements of this group resemble those of the N group, but are usually quadrivalent. Vanadium V 51 (International=51.0) a brilliant, crystalline metal; sp. gr.=5.5; which forms a series of oxides similar to those of N. No salts of V are known, but salts of vanadyl (VO) are numerous, and are used in the manufacture of aniline black. Columbium (Niobium) Cb. 93 (International=93.1 a bright, steel-gray metal; sp. gr. 7.06; which burns in air to Cb 2 3 and in Cl to CbCl 5 ; not attacked by acids. Tantalum Ta 181 ( International=181.5 ) closely resembles Cb in its chemical characters. VII. MOLYBDENUM GROUP. MOLYBDENUM TUNGSTEN OSMIUM. The position of this group is doubtful ; and it is probable that the lower oxides will be found to be basic in character, in which case the group should be transferred to the third class. Molybdenum Mo 96 a brittle white metal. The oxide Mo0 3 , molybdic anhydride, combines with H 2 to form a number of acids; the ammonium salt of one of which is used as a reagent for H 3 P0 4 , with which it forms a conjugate acid, phosphomolybdic acid, used as a reagent for the alkaloids. Tungsten Wolframium W 184 a hard, brittle metal; sp. gr. 17.4. The oxide, W0 3 tungstic anhydride, is a yellow powder, form- ing with H 2 several acid hydrates ; one of which, metatungstic acid, is used as a test for the alkaloids, as are also the conjugate silico- tungstic and phosphotungstic acids. Tissues impregnated with sodium tungstate are rendered uninflammable. Osmium Os 191 (International=190.9) occurs in combina- tion with Ir in Pt ores; combustible and readily oxidized to Os0 4 . This oxide, known as osmic acid, forms colorless crystals, soluble in H 2 0, which gives off intensely irritating vapors. It is used as a staining agent by histologists, and also in dental practice. CLASS IV. AMPHOTERIC ELEMENTS. Elements whose Oxides unite with Water, some to form Bases, others to form Acids; which form Oxysalts. The elements of this class are intermediate between the acidulous and the basylous elements, not only in the chemical relations of their oxides, but also in the products of their electrolytic dissociation. While the acidulous elements usually exist in ionized solutions in anions, which may be simple or compound, and the basylous elements exist only in cations, which are always simple, the amphoteric elements may exist in either anion or cation. When they occur in cations the ions are almost always simple, as triaurion, Au ' ' ' , dif errion, Fe ' ' , plumbion, Pb" etc., although rarely they are compound, as diurany- lion, U0 2 ". When they occur in anions these are invariably com- pounds, as dichromanion, Cr 2 7 ", permanganion, Mn0 4 ", ferrocya- nidion, Fe(CN) 6 "", etc. I. GOLD GROUP. GOLD. Symbol=Au (Aurum) Atomic weight=197 (International^ 197.2) Molecular weight=394:. Sp. gr.=l9.25S 19.367. Gold forms two series of compounds ; in one, AuCl, it is univalent ; in the other, AuCl 3 , trivalent. Its hydroxide, auric acid, Au (OH) 3 , corresponds to the oxide, Au 2 3 . Its oxysalts are unstable. It is yellow or red by reflected light, green by transmitted light, reddish purple when finely divided; not very tenacious; softer than silver; very malleable and ductile. It is not acted on by H 2 or air, at any temperature, nor by any single acid. It combines directly with Cl, Br, I, P, Sb, As and Hg. It dissolves in nitrohydrochloric acid. Aurous Chloride AuCl is produced when auric chloride is heated to 185 (365 F.). Auric Chloride Gold trichloride AuC\ 3 303.5 obtained by dissolving Au in aqua regia, evaporating at 100, and purifying by crystallization from H 2 0. Deliquescent, yellow prisms, very soluble in H 2 0, alcohol and ether; readily decomposed, with separation of Au, by contact with P, or with reducing agents. Its solution, treated with the chlorides of tin, deposits a purple double stannate of Sn and Au, called "purple of Cassius." With alkaline chlorides it forms 129 130 TEXT-BOOK OF CHEMISTRY double chlorides, such as auri et sodii chloridum (U. S. P.), which is a mixture of equal parts of gold chloride and sodium chloride. Analytical Characters. (1) With H 2 S, from neutral or acid solu- tion : a blackish brown ppt. in the cold ; insoluble in HN0 3 and in HC1; soluble in aqua regia, and in yellow NH 4 HS. (2) With stan- nous chloride and a little chlorine water, a purple-red ppt., insoluble in HC1. (3) With ferrous sulphate: a brown deposit, which assumes the luster of gold when dried and burnished. II. IRON GROUP. CHROMIUM MANGANESE IRON. The elements of the group form two series of compounds. In one they are bivalent, as in FeCU or MnS0 4 , forming the -ous salts; while in the other they are trivalent, as in FeCl 3 , forming the -ic salts. They form several oxides; of which the oxide M0 3 is an anhydride, corresponding to which are acids and salts. Most of the other oxides are basic. CHROMIUM. Symbol=Cr Atomic weight=52 (International=52,.Q) Molec- ular weight=l04:. Sp. #r.=6.8. Occurs in nature principally as chrome ironstone, a double oxide of Cr and Fe. The element is separated with difficulty by reduction of its oxide by charcoal, or of its chloride by sodium. It is a hard, crystalline, almost infusible metal. Combines with O only at a red heat. It is not attacked by acids, except HC1 ; is readily attacked by alkalies. Chromic Oxide Chromium Sesquioxide Cr 2 3 152 obtained by heating potassium dichromate with sulphur: K 2 Cr 2 7 +S=K 2 S0 4 +Cr 2 3 It is green; insoluble in H 2 0, acids and alkalies; fusible with difficulty, and not decomposed by heat ; not reduced by H. At a red heat in air, it combines with alkaline hydroxides and nitrates, to form chromates. It forms two series of salts, the terms of one of which are green, those of the other violet. The alkaline hydroxides separate a bluish-green hydrate from solutions of the green salts, and a bluish violet hydrate from those of the violet salts. Chromium Trioxide Chromic anhydride Chromium Tri- oxidum (U. S. P.) Cr0 3 100 is formed by decomposing a solu- tion of potassium dichromate by excess of H,S0 4 , and crystallizing: K 2 CrA+H 2 S0 4 =K 2 S(Vr-H 2 0+2Cr0 3 It crystallizes in deliquescent, crimson prisms, very soluble in ILO MANGANESE 131 and in dilute alcohol. It is a powerful oxidant, capable of igniting strong- alcohol. The true chromic acid has not been isolated, but salts are known which correspond to three acid hydrates: H 2 Cr0 4 =chromic acid; H 2 Cr 2 7 =dichromic acid; and H 2 Cr 3 10 =trichromic acid. Sulphates. A violet sulphate crystallizes in octahedra, (Cr) 2 (S0 4 ) 3 -|-15Aq, and is very soluble in H 2 0. At 100 it is converted into a green salt, (Cr) 2 (S0 4 ) 3 +5Aq, soluble in alcohol; which, at higher temperatures, is converted into the red, insoluble, anhydrous salt. Chromic sulphate forms double sulphates, containing 24 Aq, with the alkaline sulphates. (See Alums.) Analytical Characters. CHROMOUS SALTS. (1) Potash: a brown ppt. (2) Ammonium hydroxide: greenish white ppt. (3) Alkaline sulphides: black ppt. (4) Sodium phosphate: blue ppt. CHROMIC SALTS. (1) Potash: green ppt.; an excess of precipitant forms a green solution, from which Cr 2 3 separates on boiling. (2) Ammonium hydroxide: greenish-gray ppt. (3) Ammonium sulphy- drate : greenish ppt. CHROMATES. (1) H 2 S in acid solution: brownish color, changing to green. (2) Ammonium sulphydrate: greenish ppt. (3) Barium chloride: yellowish ppt. (4) Silver nitrate: brownish red ppt., soluble in HN0 3 or NH 4 OH. (5) Lead acetate : yellow ppt., soluble in potash, insoluble in acetic acid. MANGANESE. $i/wboZ=Mn Atomic weight =55 (International=54:.93 ) Mo- lecular weight=110. Sp. gr.=l.l38 7.206. Occurs chiefly in pyrolusite, Mn0 2 , hausmanite, Mn 3 4 , braunite, Mn 2 3 , and manganite, Mn 2 3 , H 2 0. A hard, grayish, brittle metal; fusible with difficulty ; obtained by reduction of its oxides by C at a white heat. It is not readily oxidized by cold, dry air ; but is super- ficially oxidized when heated. It decomposes H 2 0, liberating H, and dissolves in dilute acids. Oxides. Manganese forms six oxides, or compounds representing them: Manganous oxide, MnO; manganous manganic oxide, Mn 3 4 ; manganic oxide, Mn 2 3 ; manganese dioxide, Mn0 2 , and manganese heptoxide, Mn 2 7 , are known free. Manganese trioxide, Mn0 3 , has not been isolated. MnO and Mn 2 3 are basic ; Mn 3 4 and Mn0 2 are indifferent oxides; and Mn0 3 and Mn 2 7 are anhydrides, corresponding to the manganates and permanganates. Manganese dioxide Black oxide of manganese Mn0 2 86 exists in nature as pyrolusite, the principal ore of manganese, in steel gray, or brownish black, imperfectly crystalline masses. At a red heat it loses 12 per cent, of 0: 3Mn0 2 =Mn 3 4 +0 2 ; and 132 TEXT-BOOK OP CHEMISTRY at a white heat, a further quantity of is given off: 2Mn 3 4 = 6MnO-f-(X. Heated with H 2 S0 4 , it gives off 0, and forms manga- nous sulphate: 2MnO 2 +2H 2 S0 4 =2MnS0 4 +2H 2 0+0 2 . With H( 1 1 it yields manganous chloride, H 2 and Cl: Mnb 2 +4HCl=MnCl 2 + 2H 2 0-f C1 2 . It is not acted on by HN0 3 . The precipitated manganese dioxide ( Mangani dioxidum praecipi- tatum) of the U. S. P. contains not less than 80 per cent, of Mn0 2 . Salts of Manganese. Manganese forms two series of salts: Manganous salts, containing Mn"; and manganic salts, containing (Mil.,)"; the former are colorless or pink, and soluble in water; the latter are unstable. Manganous Sulphate MnSO^+nAq 150+?il8 is formed by the action of H 2 S0 4 on Mn0 2 . Below 6 it crystallizes with 7Aq, and is isomorphous with ferrous sulphate; between 7-20 it forms crystals with 5 Aq, and is isomorphous with cupric sulphate ; between 20-30 it crystallizes with 4 Aq. It is rose-colored, darker as the proportion of Aq increases, soluble in H 2 0, insoluble in alcohol. With the alkaline sulphates it forms double salts, with 6 Aq. Analytical Characters. MANGANOUS. (1) Potash: white ppt., turning brown. (2) Alkaline carbonates: white ppts. (3) Ammo- nium sulphydrate: flesh-colored ppt., soluble in acids, sparingly soluble in excess of precipitant. (4) Potassium ferrocyanide : faintly reddish white ppt., in neutral solution; soluble in HC1. (5) Potas- sium cyanide: rose-colored ppt. forming brown solution with excess. MANGANIC. (1) H,S: ppt. of sulphur. (2) Ammonium sulphy- drate: flesh-colored ppt. (3) Potassium ferrocyanide: greenish ppt. (4) Potassium f erricyanide : brown ppt. (5) Potassium cyanide: light brown ppt. MANGANATES are green salts, whose solutions are only stable in presence of excess of alkali, and turn brown when diluted and acidu- lated. PERMANGANATES form red solutions, which are decolorized by S0 2 , other reducing agents, and many organic substances. IRON. Symbol ~FQ (Ferrum) Atomic weight^ (International^ 55.84) Molecular weight- 112. 8p. gr.=7.251.9. Occurrence. Free, in small quantity only, in platinum ores and meteorites. As Fe 2 3 in red hematite and specular iron; as hydrates of Fe 2 3 in brown hematite and oolitic iron; as Fe 3 4 in magnetic iron; as FeCO 3 in spathic iron, clay ironstone and bog ore; and as FeS 2 in pyrites. It is also a constituent of most soils and clays, exists in many mineral waters, and in the red blood pigment of animals. Preparation. In working the ores, reduction is first effected in a IRON 133 blast furnace, into which alternate layers of ore, coal and limestone are fed from the top while air is forced in from below. In the lower part of the furnace CO, is produced, at the expense of the coal; higher up it is reduced by the incandescent fuel to CO, which, at a still higher point, reduces the ore: Fe 2 3 +3C=3CO+Fe 2 The fused metal, so liberated, collects at the lowest point, under a layer of slag; and is drawn off to be cast as pig iron. This product is then purified, by burning out impurities, in the process known as puddling. Pure iron is prepared by reduction of ferrous chloride, or of ferric oxide, by H at a temperature approaching redness. Varieties. Cast iron is a brittle, white or gray, crystalline metal, consisting of Fe 89-90% ; C 1-4.5% ; and Si, P, S, and Mn. As pig iron, it is the product of the blast-furnace. Wrought, or bar iron, is a fibrous, tough metal, freed in part from the impurities of cast iron, by refining and puddling. Steel is Fe combined with a quantity of C, less than that existing in cast iron, and greater than that in bar iron. It is prepared by cementation; which consists in causing bar iron to combine with C; or by the Bessemer method; which, as now used, consists in burning the C out of molten cast iron, to which the proper proportion of C is then added in the shape of spiegel eisen, an iron rich in Mn and C. The purest forms of commercial iron are those used in piano- strings, the teeth of carding machines and electro magnets ; known as soft iron. Reduced iron Ferrum reductum (U.S. P.) is Fe, more or less mixed with Fe 2 3 and Fe 3 4 , obtained by heating Fe 2 3 in H : Fe 2 3 +3H 2 =3H 2 0+Fe 2 The official ferrum reductum contains not less than 90 per cent, of metallic iron. Properties. Physical. Pure iron is silver white, quite soft; crystallizes in cubes or octahedra. Wrought iron is gray, hard, very tenacious, fibrous, quite malleable and ductile, capable of being welded, highly magnetic, but only temporarily so. Steel is gray, very hard and brittle if tempered, soft and tenacious if not, permanently magnetic. Chemical. Iron is not altered by dry air at the ordinary tem- perature. At a red heat it is oxidized. In damp air it is converted into a hydrate, iron rust. Tinplate is sheet iron, coated with tin; galvanized iron is coated with zinc, to preserve it from the action of damp air. Iron unites directly with Cl, Br, I, S, N, P, As, and Sb. It dis- solves in HC1 as ferrous chloride, while H is liberated. Heated with strong H 2 S0 4 it gives off S0 2 ; with dilute H 2 S0 4 , H is given off and 134 TEXT-BOOK OF CHEMISTRY ferrous sulphate formed. Dilute HNO. { dissolves Fe, but the concen- trated acid renders it passive, when it is not dissolved by either con- centrated or dilute HN0 3 , until the passive condition is destroyed by contact with Pt, Ag or Cu, or by heating to 40. Compounds of Iron. Oxides. Three oxides of iron exist free: FeO ; Fe 2 O 3 ; Fe 3 O 4 . Ferrous Oxide. Protoxide of iron FeO 72 is formed by heat- ing Fe 2 3 in CO or CO,. Ferric Oxide. Sesquioxide or peroxide of iron Fe 2 3 160 occurs in nature (see above), and is formed when ferrous sulphate is strongly heated, as in the manufacture of pyrosulphuric acid. It is a reddish, amorphous solid, is a weak base, and is decomposed at a white heat into and Fe 3 4 . Magnetic Oxide Ferroso-ferric oxide Black oxide Fe 3 4 232 is the natural loadstone, and is formed by the action of air, or steam, upon iron at high temperatures. It is probably a com- pound of ferrous and ferric oxides (FeO, Fe 2 3 ), as acids produce with it mixtures of ferrous and ferric salts. Hydroxides Ferrous. When a solution of a ferrous salt is de- composed by an alkaline hydroxide, a greenish-white hydroxide, Fe(OH) 2 is deposited; which rapidly absorbs from the air, with formation of ferric hydroxide. Ferric. When an alkali is added to a solution of a ferric salt, a brown, gelatinous precipitate is formed, which is ferric hydroxide, Fe(OH) 3 : 2FeCl 3 +6NH 4 OH=6NH 4 Cl+2Fe(OH) 3 It is not formed in the presence of fixed organic acids or of sugar in sufficient quantity. If preserved under H 2 0, it is partly oxidized, forming an oxyhydrate which is incapable of forming ferrous arsenate with As 2 3 . (See p. 115.) If recently precipitated ferric hydroxide is dissolved in solution of ferric chloride or acetate, and subjected to dialysis, almost all the acid passes out, leaving in the dialyzer a dark red solution, which prob- ably contains this colloid hydrate, and which is instantly coagulated by a trace of H 2 S0 4 , by alkalies, many salts, and by heat; dialyzed iron. Sulphides. Ferrous Sulphide Protosulphide of iron FeS 88 is formed : (1) By heating a mixture of finely-divided Fe and S to redness; (2) by pressing roll-sulphur on white-hot iron; (3) in a hydnitcd condition, FeS, H 2 0, by treating a solution of a ferrous salt with an alkaline sulphydrate. The dry sulphide is a brownish, brittle, magnetic solid, insoluble in ILO, soluble in acids with evolution of H 2 S. The hydrate is a black powder, which absorbs from the air, turning yellow, by IRON 135 formation of Fe 2 3 , and liberation of S. It occurs in the feces of persons .taking chalybeate waters or preparations of iron. Ferric Sulphide Sesquisulphide Fe,S 3 208 occurs in nature in copper pyrites, and is formed when the disulphide is heated to redness. Ferric Disulphide FeS 2 120 occurs in the white and yellow Martial pyrites, used in the manufacture of H 2 S0 4 . When heated in air, it is decomposed into S0 2 and magnetic pyrites: 3FeS 2 +20 2 =Fe 3 S 4 +2SO 2 Chlorides. Ferrous Chloride ProtochlorideFeC\ 2 127 is produced: (1) by passing dry HC1 over red-hot Fe; (2) by heating ferric chloride in H. The anhydrous compound is a yellow, crystalline, volatile, and very soluble solid. The hydrated is in greenish, oblique rhombic prisms, deliquescent and very soluble in H 2 and alcohol. When heated in air it is converted into ferric chloride, and an oxy- chloride. Ferric Chloride Sesquichloride Perchloride Ferri chloridum (U. S. P.) FeCl 3 is produced by heating FeCl 2 in aqua regia: 3FeCl 2 +HNO 3 +3HCl=2H 2 0+NO+3FeCl 3 (2) By dissolving ferric hydroxide in HC1; (3) by the action of Cl or of HNO 3 on solution of ferrous chloride. The anhydrous compound forms reddish-violet, crystalline plates, very deliquescent. The hydrates form yellow, nodular, imperfectly crystalline masses, or rhombic plates, very soluble in H 2 0, soluble in alcohol and ether. In solution, it is converted into FeCl 2 by reducing agents. The Liquor ferri chloridi (U. S. P.) is an aqueous solution of this compound, containing excess of acid. The Tincture ferri chloridi (U. S. P.) is the solution, diluted with alcohol. Sulphates. Ferrous Sulphate ProtosulpJiate Green vitriol Copperas Ferri sulphas (U. S. P.) FeS0 4 +7Aq 152+126 is formed: (1) by oxidation of the sulphide, Fe 3 S 4 , formed in the manu- facture of H 2 S0 4 ; (2) by dissolving Fe in dilute H 2 S0 4 . It forms green, efflorescent, oblique rhombic prisms, quite soluble in H 2 0, insoluble in alcohol. It loses 6 Aq at 100 (Ferri sulphas exsiccatus, U. S. P.) ; and the last Aq at about 300. At a red heat it is decomposed into Fe 2 3 ; S0 2 and S0 3 . By exposure to air it is gradually converted into a basic ferric sulphate Fe 2 (S0 4 ) 3 , 5Fe 2 3 . Ferric Sulphates are quite numerous, and are formed by oxida- tions of ferrous sulphate under different conditions. The normal sul- phate, (Fe 2 )(S0 4 ) 3 , is formed by treating solution of FeS0 4 with HN0 3 , and evaporating, after addition of one molecule of H 2 S0 4 for each two molecules of FeS0 4 . The Liquor ferri tersulphatis (U. S. P.), contains this salt. It is a yellowish white, amorphous solid. 136 TEXT-BOOK OF CHEMISTRY Of the many basic ferric sulphates, the only one of medical in- terest is Monsel's salt, 5Fe 2 (S0 4 ) 3 +4Fe.,03, which exists in the Liquor ferri subsulphatis (U. S. P.). Its solution is decolorized, and forms a white deposit with excess of H 2 S0 4 . Phosphates. Triferrous Phosphater-Fe 3 (P0 4 ) 2 358. A white precipitate, formed by adding disodic phosphate to a solution of a ferrous salt, in presence of sodium acetate. By exposure to air it turns blue; a part being converted into ferric phosphate. It is insoluble in H 2 ; sparingly soluble in H 2 containing carbonic or acetic acid. It is probably this phosphate, capable of turning blue, which sometimes occurs in the lungs in phthisis, in blue pus, and in long- buried bones. Ferric Phosphate FeP0 4 151 is produced by the action of an alkaline phosphate on ferric chloride. It is soluble in HC1, HN0 3 , citric and tartaric acids, insoluble in phosphoric acid and in solu- tion of disodic phosphate. The ferri phosphas (U. S. P.) is a com- pound, or mixture of this salt with disodic citrate, which is soluble in water. There exist quite a number of basic ferric phosphates. Acetates. Ferrous Acetate Fe(C 2 H 3 O 2 ) 2 174 is formed by decomposi- tion of ferrous sulphate by calcium acetate, in soluble, silky needles. Ferric Acetates. The normal salt Fe(C 2 H 3 O 2 )3, is obtained by adding slight excess of ferric sulphate to lead acetate, and decanting after twenty-four hours. It is dark-red, uncrystallizable, very soluble in alcohol, and in H 2 0. If its solution be heated it darkens suddenly, gives off acetic acid, and contains a basic acetate. When boiled, it loses all its acetic acid, and deposits ferric hydrate. When heated in closed vessels to 100, and treated with a trace of mineral acid, it deposits the modified ferric hydrate. Ferrous Carbonate FeC0 3 Spathic iron 116 occurs as an ore of iron, and is obtained, in a hydrated form, by adding an alkaline carbonate to a ferrous salt. It is a greenish, amorphous powder, which on exposure to air turns red by formation of ferric hydrate ; a change which is retarded by the presence of sugar, hence the addition of that substance in the ferri carbonas saccharatus (U. S. P.). It is insoluble in pure H 2 0, but soluble in H 2 containing carbonic acid, probably as ferrous bicarbonate, H 2 Fe(C0 3 ) 2 , in which form it occurs in chalybeate waters. Citrates. Ferric Citrate Fe 2 ( C 6 H 8 O, ) 2 +6Aq 490+ 108 is in garnet- colored scales, obtained by dissolving ferric hydrate in solution of citric acid, and evaporating the solution at about 60. It loses 3Aq at 120, and the re- mainder at 150. If a small quantity of ammonium hydroxide is added, before the evaporation, the product consists of the- modified citrater=ferri et ammonii citras (U. S. P.), which only reacts with potassium ferrocyanide after addition of HC1. The various citrates of iron and alkaloids are not definite compounds. Ferric Ferrocyanide Prussian blue (Fe 2 ) 2 (FeC fl N a ) 3 +18Aq 860+324 is a dark-blue precipitate, formed when potassium ferrocyanide is added to a URANIUM 137 ferric salt. It is insoluble in H a O, alcohol and dilute acids; soluble in oxalic acid solution (blue ink). Alkalies turn it brown. Ferrous Ferricyanide Turnbull's blue Fe[Fe(CN) 6 ] a -j-nAq 592-|-nl8 is a dark blue substance produced by the action of potassium ferricyanide on ferrous salts. Heated in air it is converted into Prussian blue and ferric oxide. General methods of oxidizing a ferrous salt to the ferric state. (1) By passing chlorine gas through a solution of the ferrous salt: 2FeCl 2 +Cl 2 ==2FeCl a 6FeS0 4 +3Cl 2 =2FeCi 8 +2Fe 2 (S0 4 ) 8 (2) By heating a solution of the ferrous salt with nitric acid : 3FeCl 2 +4HN0 3 =Fe (N0 8 ) 2 +NO+2H 2 0+2FeCl 3 3FeS0 4 +4HN0 3 =Fe (N0 3 ) 2 +NO+2H 2 0+Fe 2 ( S0 4 ) , General methods of reducing a ferric salt to the ferrous, state. (1) By adding zinc and hydrochloric acid to a solution of a ferric salt ; the nascent hydrogen which is liberated will effect the reduction : f 2FeCl 3 +H 2 =2HCl+2FeCl 2 (2) By passing sulphuretted hydrogen through a solution of a ferric salt: 4FeCl 3 -f2H 2 S=S 2 +4HCl+4FeCl 2 Analytical Characters. FERROUS Are acid; colorless when an- hydrous, pale green when hydrated; oxidized by air to basic ferric compounds. (1) Potash: greenish white ppt. ; insoluble in excess; changing to green or brown in air. (2) Ammonium hydroxide; greenish ppt. ; soluble in excess ; not formed in presence of ammo- niacal salts. (3) Ammonium sulphydrate: black ppt.; insoluble in excess; soluble in acids. (4) Potassium ferrocyanide (in absence of ferric salts) : white ppt.; turning blue in air. (5) Potassium ferri- cyanide : blue ppt. ; soluble in KOH ; insoluble in HC1. FERRIC Are acid, and yellow or brown. (1) Potash, or ammo- nium hydroxide : voluminous, red-brown ppt. ; insoluble in excess. (2) Hydrogen sulphide, in acid solution: milky ppt. of sulphur; ferric reduced to ferrous compound. (3) Ammonium sulphydrate: black ppt. ; insoluble in excess; soluble in acids. (4) Potassium ferro- cyanide: dark blue ppt.; insoluble in HC1; soluble in KOH. (5) Potassium thiocyanate : dark-red color ; prevented by tartaric or citric acid; discharged by mercuric chloride. (6) Tannin: blue-black color. III. URANIUM GROUP. URANIUM. Symbol^ Atomic weig~kt=238(International=2383)Sp. gr.=lSA. This element is usually classed with Fe and Cr, or with Ni and Co. It does not, however, form compounds resembling the ferric; it 138 TEXT-BOOK OF CHEMISTRY forms a series of well-defined uranates, and a series of compounds of the radical uranyl (UO)'. Uranium nitrate, Uranii nitras, (U. S. P.) contains not less than 98 per cent, of U0 2 (N0 3 ) 2 -{-6Aq. (uranyl nitrate). Standard solutions of its acetate or nitrate are used for the quantitative determination of H 3 P0 4 . IV. LEAD GROUP. LEAD. ^Pb (Plumbum) Atomic weight=201 (International^ 207.20) Molecular weight=414:Sp. #r.=11.445. Lead is usually classed with Cd, Bi, or Cu and Hg. It differs, however, from Bi in being bivalent or quadrivalent, but not triva- lent, and in forming no compounds resembling those of bismuthyl (BiO) ; from Cd, in the nature of its compounds; and from Cu and Hg in forming no compounds similar to the mercurous and cuprous salts. Indeed, the nature of the Pb compounds is such that the element is best classed in a group by itself, which finds a place in this class by virtue of the existence of potassium plumbate. Occurrence. Its most abundant ore is galena, PbS. It also occurs in white lead ore, PbC0 3 , in anglesite, PbS0 4 , and in horn lead, PbCl 2 . Preparation. Galena is first roasted with a little lime. The mix- ture of PbO, PbS, and PbS0 4 obtained is strongly heated in a rever- beratory furnace, when S0 2 is driven off: 2PbO+PbS=S0 2 +3Pb and PbS+PbS0 4 =2S0 2 +2Pb The impure work lead, so formed, is purifie'd by fusion in air, and removal of the film of oxides of Sn and Sb. If the ore is rich in Ag, that metal is extracted, by taking advantage of the greater fusi- bility of an alloy of Pb and Ag, than of Pb alone; and subsequent oxidation of the remaining Pb. Properties. Physical. It is a bluish white metal; brilliant upon freshly cut surfaces; very soft and pliable; not very malleable or ductile; crystallizes in octahedra; a poor conductor of electricity; a better conductor of heat. When expanded by heat it does not, on cooling, return to its original volume. Chemical. When exposed to air it is oxidized, more readily and completely at high temperatures. The action of H,0 on Pb varies with the conditions. (See p. 67.) Pure unaerated H 2 has no action upon it. By the combined action of air and moisture Pb is oxidi/rd, and the oxide dissolved in the H 2 0, leaving a metallic surface for the contimumrc of the action. The solvent action of H 2 upon Pb is LEAD 139 increased, owing to the formation of basic salts, by the presence of nitrogenized organic substances, nitrates, nitrites, and chlorides. On the other hand, carbonates, sulphates, and phosphates, by their ten- dency to form insoluble coatings, diminish the corroding action of H 2 0. Carbonic acid in small quantity, especially in presence of carbonates, tends to preserve Pb from solution, while H 2 highly charged with it (soda water) dissolves the metal readily. Lead is dissolved, as a nitrate, by HN0 3 . H 2 S0 4 , when cold and moderately concentrated, does not affect it; but, when heated, dissolves it the more readily as the acid is more concentrated. It is attacked by HC1 of sp. gr. 1.12, especially if heated. Acetic acid dissolves it as acetate, or, in the presence of CO,, converts it into white lead. Oxides. Lead Monoxide Massicot Litharge Plumbi oxidum (U. S. P.) PbO 223 is prepared by heating Pb, or its carbonate, or nitrate, in air. If the product has been fused, it is litharge; if not, massicot. It forms copper-colored, mica-like plates, or a yellow powder; or crystallizes, from its solution in soda or potash, in white, rhombic dodecahedra, or in rose-colored cubes. It fuses near a red heat, and volatilizes at a white heat; sp. gr. 9.277 9.5. It is spar- ingly soluble in H 2 0, forming an alkaline solution. Heated in air to 300 it is oxidized to minium. It is readily reduced by H or C. With Cl it forms PbCl, and 0. It is a strong base; decomposes alkaline salts, with liberation of the alkali. It dis- solves in HN0 3 , and in hot acetic acid, as nitrate or acetate. When ground up with oils it saponifies the glycerol ethers, the Pb combining with the fatty acids to form Pb soaps, one of which, lead oleate, is the emplastrum plumbi, lead plaster, diachylon plaster (U. S. P.). It also combines with the alkalies and earths to form plumbites. Calcium plumbite, CaPb,0 3 , is a crystalline salt, formed by heating PbO with milk of lime, and used in solution as a hair dye. Plumboso-plumbic Oxide Red oxide Minium Red lead Pb 3 4 685 is prepared by heating massicot to 300 in air. It ordinarily has the composi- tion Pb 3 4 , and has been considered as composed of PbO 2 , 2PbO; or a basic lead salt of plumbic acid, Pb0 3 Pb, PbO. An orange-colored variety is formed when lead carbonate is heated to 300. It is a bright red powder, sp. gr. 8.62. It is converted into PbO when strongly heated, or by the action of reducing agents. HN0 3 changes its color to brown, dissolving PbO and leaving Pb0 2 . It is decomposed by HC1, with formation of PbCl 2 , H 2 O and Cl. Lead Dioxide. Plumbic anhydride Pb0 2 239 is prepared, either by dissolving the PbO out of red lead by dilute HN0 3 , or by passing a current of Cl through H 2 0, holding lead carbonate in sus- pension. It is a dark, reddish brown, amorphous powder; sp. gr. 8.903- 9.190 ; insoluble in H 2 0. Heated, it loses half its 0, and is converted 140 TEXT-BOOK OF CHEMISTRY into PbO. It is a valuable oxidant. It absorbs S0 2 to form. PbS0 4 . It combines with alkalies to form plumbates, M 2 Pb0 3 . Lead Sulphide Galena PbS 239 exists in nature. It is also formed by direct union of Pb and S; by heating PbO with S, or vapor of CS 2 ; or by decomposing a solution of a Pb salt by H 2 S or an alkaline sulphide. The native sulphide is a bluish gray, and has a metallic luster; sp. gr. 7.58; that formed by precipitation is a black powder; sp. gr. 6.924. It fuses at a red heat and is partly sublimed, partly converted into a subsulphate. Heated in air it is converted into PbS0 4 , PbO and S0 2 . Heated in H it is reduced. Hot HN0 3 oxidizes it to PbS0 4 . "Hot HC1 converts it into PbCl 2 . Boiling H,S0 4 converts it into PbS0 4 and S0 2 . Lead Chloride PbCl 2 278 is formed by the action of Cl upon Pb at a red heat; by the action of boiling HC1 upon Pb, and by double decomposition between a lead salt and a chloride. It crystallizes in plates, or hexagonal needles; sparingly soluble in cold H 2 O, less soluble in H 2 O containing HC1; more soluble in hot H 2 O, and in con- centrated HC1. Several oxychlorides are known. Cassel, Paris, Verona, or Turner's yellow is PbCl 2 , 7PbO. Lead Iodide PbI 2 461 is deposited, as a bright yellow powder, when a solution of potassium iodide is added to a solution of Pb salt. Fused in air, it is converted into an oxyiodide. Light and moisture decompose it, with liberation of I. It is almost insoluble in H 2 O, soluble in solutions of ammonium chloride, sodium hyposulphite, alkaline iodide, and potash. Salts of Lead. Nitrates. Lead Nitrate Pb( NO 3 ) 2 is formed by solution of Pb, or of its oxides, in excess of HN0 3 . It forms anhydrous crystals; soluble in H 2 0. Heated, it is decomposed into PbO, and N0 2 . Lead Sulphate. PbS0 4 303 is formed by the action of hot concentrated H 2 S0 4 on Pb; or by double decomposition between a sulphate and a Pb salt in solution. It is a white powder, almost in- soluble in H 2 0, soluble in concentrated H 2 S0 4 , from which it is de- posited by dilution. Lead Chromate Chrome yellow PbCr0 4 323 is formed by decomposing Pb(N0 3 ) 2 with potassium chromate. It is a yellow, amorphous powder, insoluble in H 2 0, soluble in alkalies. Acetates. Lead Acetate Salt of Saturn Sugar of Lead Plumbi acetas (U. S. P.) Pb(C 2 H 3 2 ),+3Aq 325+54 is formed by dissolving PbO in acetic acid ; or by exposing Pb in contact with acetic acid to air. It crystallizes in large, oblique rhombic prisms, sweetish, with a metallic after-taste; soluble in H 2 and alcohol; its solutions being ;icid. In air it effloresces, and is superficially converted into car- bonate. It fuses at 75.5; loses Aq and a part of its acid at 100, fnnning the sesquibasic acetate, 2[Pb(C 2 H 3 2 ) 2 ]Pb(OH) 2 ; at 280 LEAD 141 it enters into true fusion, and, at a slightly higher temperature, is decomposed into C0 2 , Pb, and acetone. Its aqueous solution dis- solves PbO, with formation of basic acetates. Sexbasic Lead Acetate Pb(C 2 H 3 2 ) OH, 2PbO 729 is the main constituent of Goulard's extract=Liquor plumbi subacetatis (U. S. P.), and is formed by boiling a solution of the neutral acetate 'with PbO in fine powder. It contains 18 per cent, of Pb. The solu- tion becomes milky on addition of ordinary H 2 0, from formation of the sulphate and carbonate. The liquor plumbi subacetatis dilutus (U. S. P.) contains 4 parts of the liquor plumbi subacetatis in 100 parts of water. Lead Carbonate PbC0 3 267 occurs in nature as cerusite ; and is formed, as a white, insoluble powder, when a solution of a Pb com- pound is decomposed by an alkaline carbonate, or by passing C0 2 through a solution containing Pb. White lead or ceruse, or plumbi carbonas, is a basic carbonate (PbC0 3 ) 2 , Pb(OH) 2 775 mixed with varying proportions of other basic carbonates. It is usually prepared by the action of C0 2 on a solu- tion of the subacetate, prepared by the action of acetic acid on Pb and PbO. It is a heavy, white powder, insoluble in H 2 0, except in the presence of C0 2 ; soluble in acids with effervescence ; and decomposed by heat into C0 2 and PbO. White lead enters into the composition of almost all oil-paints, being used to dilute other pigments. The darkening of oil-paintings is due to the formation of the black lead sulphide by atmospheric H 2 S. Analytical Characters. (1) Hydrogen sulphide, in acid solution: a black ppt. ; insoluble in alkaline sulphides, and in cold, dilute acids. (2) Ammonium sulphydrate: black ppt.; insoluble in excess. (3) Hydrochloric acid: white ppt., in not too dilute solution; soluble in boiling H 2 0. (4) Ammonium hydroxide: white ppt.; insoluble in excess. (5) Potash: white ppt.; soluble in excess, especially when heated. (6) Sulphuric acid: white ppt.; insoluble in weak acids, sol- uble in solution of ammonium tartrate. (7) Potassium iodide: yel- low ppt. ; sparingly soluble in boiling H 2 ; soluble in large excess. (8) Potassium chromate: yellow ppt.; soluble in KOH solution. (9) Iron or zinc separate the element from solution of its salts. Action on the Economy. All the soluble compounds of Pb, and those which, although not soluble, are readily convertible into soluble compounds by H 2 0, air, or the digestive fluids, are actively poisonous. Some are also in- jurious by their local action upon tissues with which they come in contact; such are the acetate, and, in less degree, the nitrate. The chronic form of lead intoxication, painter's colic, etc., is purely poisonous, and is produced by the continued absorption of minute quantities of Pb, either by the skin, lungs, or stomach. The acute form presents symptoms referable to the local, as well as to the poisonous, action of the Pb salt, and is usually caused by the ingestion of a single dose of the acetate or carbonate. Metallic Pb, although probably not poisonous of itself, causes chronic lead- 142 TEXT-BOOK OF CHEMISTRY poisoning by the readiness with which it is convertible into compounds capable of absorption. The principal sources of poisoning by metallic Pb are: the con- tamination of drinking water which has been in contact with the metal (see p. 67); the use of articles of food, or of chewing tobacco, which has birn packed in tin-foil, containing an excess of Pb; the drinking of beer or other beverages which have been in contact with pewter; or the handling of the metal and its alloys. Almost all the compounds of Pb may produce painter's colic. The car- bonate, in painters, artists, manufacturers of white lead, and in persons sleep- ing in newly-painted rooms; the oxides, in the manufactures of glass, pottery, sealing-wax, and litharge, and by the use of lead-gla/.ed pottery; by other com- pounds, by the inhalation of the dust of cloth factories, and by the use of lead hair-dyes. Acute lead-poisoning is of by no means as common occurrence as the chronic form, and usually terminates in recovery. It is caused by the ingestion of a single dose of the acetate, subacetate, carbonate, or of red lead. In such cases the administration of magnesium sulphate is indicated; it enters into double decomposition with Pb salt to form the insoluble PbS0 4 . Lead, once absorbed, is eliminated very slowly, it becoming fixed by com- bination with the proteins, a form of combination which is rendered soluble by potassium iodide. The channels of elimination are by the perspiration, urine and bile. V. BISMUTH GROUP. BISMUTH. Symbol=Bi Atomic weight=20S Molecular weight=416. Sp. 0r.=9.677-9.935. This element is usually classed with Sb; by some writers among the metals, by others in the phosphorus group. We are led to class Bi in our fourth class, and in a group alone, because: (1) while the so-called salts of Sb are not salts of the element, but of the radical (SbO)', antimonyl, Bi enters into saline combination, not only in the radical bismuthyl (BiO)', but also as an element; (2) while the com- pounds of the elements of the N group in which those elements are quinquivalent are, as a rule, more stable than those in which they arc trivalent, Bi is trivalent in all its known compounds except one. which is very unstable, in which it is quinquivalent; (3) the hydrates of the N group are strongly acid, and their corresponding salts n te- stable and well defined ; but those hydrates of Bi which are acid are but feebly so, and the bismuthates are unstable ; (4) no compound of Bi and H is known. Occurrence. Occurs principally free, also as Bi 2 3 and Bi,S 3 . Properties. Crystallizes in brilliant, metallic rhombohedra ; hard and brittle. It is only superficially oxidized in cold air. Heated to redness in air, it becomes coated with a yellow film of oxide. In H 2 0, containing C0 2 , it forms a crystalline subcarbonate. It combines directly with BISMUTH 143 Cl, Br and I. It dissolves in hot H 2 S0 4 as sulphate, and in HN0 3 as nitrate. It is usually contaminated with As, from which it is best purified by heating to redness a mixture of powdered bismuth, potassium carbonate, soap and charcoal, under a layer of charcoal. After an hour the mass is cooled; the button is separated and fused until its surface begins to be coated with a yellowish brown oxide. Oxides. Four oxides are known : Bi 2 2 , Bi 2 3 , Bi 2 4 , and Bi 2 5 . Bismuth Trioxide Bismuthous oxide Bi 2 3 464 is formed by heating Bi, or its nitrate, carbonate or hydrate. It is a pale yellow, insoluble powder; sp. gr. 8.2; fuses at a red heat; soluble in HC1, HN0 3 and H,S0 4 and in fused potash. Magma bismuthi (U. S. P.) bismuth magma milk of bismuth contains about 6 per cent, of Bi 2 3 . Hydrates. Bismuth forms at least four hydrates. Bismuthous Hydroxide Bi(OH) 3 259 is formed, as a white precipitate, when potash or ammonium hydroxide is added to a cold solution of a Bi salt. When dried it loses H 2 0, and is converted into Bismuthyl hydroxide (BiO)OH. Bismuth Trichloride Bismuthous chloride BiCl 3 314.5 is formed by heating Bi in Cl ; by distilling a mixture of Bi and mer- curic chloride; or by distilling a solution of Bi in aqua regia. It is a fusible, volatile, deliquescent solid ; soluble in dilute HC1. On contact with H 2 it is decomposed with formation of bismuthyl chloride, (BiO)Cl, or pearl white. Bismuth Nitrate Bi(N0 3 ) 3 -f5 Aq 394+90 obtained by dis- solving Bi in HN0 3 . It crystallizes in large, colorless prisms; at 150, or by contact with H 2 O, it is converted into bismuthyl nitrate; at 260 into Bi 2 O 3 . Bismuthyl Nitrate Trinitrate or subnitrate of bismuth Flake white Bismuthi subnitras (U. S. P.) (BiO)N0 3 .H 2 304 is formed by decomposing a solution of Bi(N0 3 ) 3 with a large quantity of H 2 0. It is a white, heavy, faintly acid powder; soluble to a slight extent in H 2 when freshly precipitated, the solution depositing it again on standing. It is decomposed by pure H 2 0, but not by H 2 containing %oo ammonium nitrate. It usually contains 1 Aq, which it loses at 100. Bismuth subnitrate, as well as the subcarbonate, is liable to contamination with arsenic, which accompanies bismuth in its ores. Bismuthyl Carbonate Bismuth subcarbonate Bismuthi sub- carbonas (U. S. P.) (BiO) 2 C0 3 .H 2 526 is a white or yellowish, timorphous powder, formed when a solution of an alkaline carbonate is added to a solution of Bi(N0 3 ) 3 . It is odorless, tasteless, and in- soluble in H 2 and in alcohol. When heated to 100, it loses H 2 0, and is converted into 144 TEXT-BOOK OF CHEMISTRY (BiO) 2 C0 3 . At a higher temperature it is further decomposed into Bi 2 3 and C0 2 . The relation of the salts of bismuth to the bismuthyl salts, may be seen in the following table: BISMUTH BISMUTHYL Chloride BiCl 3 (BiO)Cl Bromide BiBr 3 (BiO)Br Nitrate BifNO,), (BiO)NO a Sulphate (Bi),(S(X) (BiO) 2 SO 4 Carbonate (Bi) 2 (C0 3 ) 8 (BiO) 2 CO 8 Analytical Characters. (1) Water: white ppt., even in presence of tartaric acid, but not of HN0 3 , HC1, or H 2 S0 4 . (2) Hydrogen sulphide, black ppt., insoluble in dilute acids and in alkaline sul- phides. (3) Ammonium sulphydrate: black ppt., insoluble in excess. (4) Potash, soda, or ammonia : white ppt., insoluble in excess, and in tartaric acid; turns yellow when the liquid is boiled. (5) Potassium f errocyanide : yellowish ppt., insoluble in HC1. (6) Potassium ferri- cyanide: yellowish ppt., soluble in HC1. (7) Infusion of galls: orange ppt. (8) Potassium iodide: brown ppt., soluble in excess. (9) Reacts with Reinsch's test (q. v.), but gives no sublimate in the glass tube. Action on the Economy. Although the medicinal compounds of bismuth are probably poisonous, if taken in sufficient quantity, the ill effects ascribed to them are in most, if not all cases, referable to contamination with arsenic. Symptoms of arsenical poisoning have been frequently observed when the sub- nitrate has been taken internally, and also when it has been used as a cosmetic. Bismuth subnitrate is frequently administered by physicians in cases of arsenical poisoning, not recognized as such during life. When preparations of bismuth are administered, the alvine discharges con- tain bismuth sulphide, as a dark brown powder. VI. TIN GROUP. TITANIUM ZIRCONIUM TIN Ti and Sn are bivalent in one series of compounds, SnCl,, and quadrivalent in another, SnCl 4 . Zr, so far as known, is always quadrivalent. Each of these elements forms an acid (or salts corre- sponding to one) of the composition of H 2 M0 3 , and a series of oxy- salts of the composition of M [V (N0 3 ) 4 . TITANIUM AND ZIRCONIUM 145 TITANIUM. Symbol = Ti Atomic weight = 48 (International = 48.1) Sp. Occurs in clays and iron ores, and as TiO, in several minerals. Titanic anhydride, Ti0 2 , is a white, insoluble, infusible powder, used in the manufacture of artificial teeth ; dissolves in fused KOH, . as potassium titanate. Titanium combines readily with N, which it absorbs from air when heated. When NH 3 is passed over red-hot Ti0 2 , it is decomposed with formation of the violet nitride, TiN 2 . Another compound of Ti and N forms hard, copper-colored, cubical crystals. ZIRCONIUM. Symbol = Zr Atomic weight = 90 (International = 90.6) Sp. Occurs in zircon and hyacinth. Its oxide, zirconia, Zr0 2 , is a white powder, insoluble in KOH. Being infusible, and not altered by exposure to air, it is used in pencils to replace lime in the calcium light. TIN. Symbol=Sn (Stannum) Atomic weight =118. 5 (International =118.7) Molecular w eight =237. Sp. gr.=7. 285-7. 293. Tin is bivalent in one series of compounds, SnCl 2 ; and quadri- valent in another, SnCl 4 . Occurrence. As tinstone (Sn0 2 ) or cassiterite, and in stream tin. Preparation. The commercial metal is prepared by roasting the ore, extracting with H 2 0, reducing the residue by heating with char- coal, and refining. Pure tin is obtained by dissolving the metal in HC1; filtering; evaporating ; dissolving the residue in H 2 : decomposing with am- monium carbonate; and reducing the oxide with charcoal. Properties. A soft, malleable, bluish white metal; but slightly tenacious; emits a peculiar sound, the tin-cry, when bent. A good conductor of heat and electricity. Air affects it but little, except when it is heated ; more rapidly if Sn is alloyed with Pb. It oxidizes slowly in H 2 ; more rapidly in the presence of sodium chloride. Its presence with Pb accelerates the action of H 2 upon the latter. It dissolves in HC1 as SnCL. In presence of a small quantity of H 2 0, HN0 3 converts it into metastannic acid. Alkaline solutions dissolve it as metastannates. It combines directly with Cl, Br, I, S, P and As. 146 TEXT-BOOK OF CHEMISTRY Tin plates are thin sheets of Fe, coated with Sn. Tin foil con- sists of thin laminae of Sn, frequently alloyed with Pb. Copper and iron vessels are tinned after brightening, by contact with molten Sn. Pewter, bronze, bell metal, gun metal, britannia metal, speculum metal, type metal, solder, and fusible metal, contain Sn. Oxides. Stannous Oxide SnO 134.5 obtained by heating the hydroxide or oxalate without contact of air. It is a white, amorphous powder, soluble in acids, and in hot, concentrated solution of potash. It absorbs readily. Stannic Oxide Sn0 2 150.5 occurs native as tinstone or cassiterite, and is formed when Sn or SnO is heated in air. It is used as a polishing material, under the name of putty powder. Hydrates. Stannous Hydroxide Sn ( OH ) 2 152.5 is a white precipitate, formed by alkaline hydroxides and carbonates in solution of SnCl 2 . Stannic Acid H 2 SnO 3 168.5 is formed by the action of alkaline hy- droxides on solutions of SnCl 4 . It dissolves in solutions of the alkaline hy- droxides, forming stannates. Metastannic Acid H 2 Sn 5 O u 770.5 is a white, insoluble powder, formed by acting on Sn with HNO 3 . Chlorides. Stannous Chloride Tin crystals. SnCl 2 +2 Aq 189.5+ 36 is obtained by dissolving Sn in HC1. It crystallizes in colorless prisms; soluble in a small quantity of H 2 O; decomposed by a large quantity, unless in the pres- ence of free HC1, with formation of an oxychloride. Loses its Aq at 100. In air it is transformed into stannic chloride and oxychloride. Oxidizing and chlorinating agents convert it into SnCl 4 . It is a strong reducing agent. Stannic Chloride Bichloride SnCl 4 260.5 is formed by acting on Sn or SnCl 2 with Cl, or by heating Sn in aqua regia. It is a fuming, yellowish liquid; sp. gr. 2.28; boils at 120. Analytical Characters. STANNOUS. (1) Potash, or soda: white ppt. ; soluble in excess; the solution deposits Sn when boiled. (2) Ammonium hydroxide: white ppt; insoluble in excess; turns olive-brown when the liquid is boiled. (3) Hydrogen sulphide: dark brown ppt.; soluble in KOH, alkaline sulphides, and hot H 2 0. (4) Mercuric chloride: white ppt., turning gray and black. (5) Auric chloride: purple or brown ppt., in presence of small quantities of HN0 3 . (6) Zinc: deposit of Sn. STANNIC. (1) Potash, or ammonia: white ppt.; soluble in excess. (2) Hydrogen sulphide: yellow ppt.; soluble in alkalies, alkaline sulphides, and hot HC1. (3) Sodium hyposulphite: yellow ppt., when heated. PLATINUM 147 VII. PLATINUM GROUP. PALLADIUM. PLATINUM. VIII. RHODIUM GROUP. RHODIUM. RUTHENIUM. IRIDIUM. The elements of these two groups, together with osmium, are usually classed as "metals of the platinum ores." They all form hydrates (or salts representing them) having acid properties. Os- mium has been removed, because the relations existing between its compounds, and those of molybdenum and tungsten, are much closer than those which they exhibit to the compounds of these groups. The separation of the remaining platinum metals into two groups is based upon resemblances in the composition of their compounds, as shown in the following tables: CHLOBIDES. PdCl 2 PtCl 2 RhCl 2 RuCl 2 ? PdCl 4 PtCl 4 RuCl 4 IrCl 4 Rh 2 Cl 6 Ru 2 Cl a Ir 2 Cl 6 OXIDES. PdO PtO RhO RuO IrO Rh 2 O 3 Ru 2 O 3 Ir 2 8 Pd0 2 Pt0 2 Rh0 2 Ru0 2 ; . . .Ir0 2 Rh0 3 Ru0 3 Ir0 3 Ru0 4 - PLATINUM. Symbol=Pi Atomic weight=195 (International=195.2) Mo- lecular weight=390Sp. gr. =21.1-21.5. Occurrence. Free and alloyed with Os, Ir, Pd, Rh, Ru, Fe, Pb, Au, Ag and Cu. Properties. The compact metal has a silvery luster; softens at a white heat ; may be welded ; fuses with difficulty ; highly malleable, ductile and tenacious. Spongy platinum is a grayish, porous mass, formed by heating the double chloride of Pt and NH 4 . Platinum black is a black powder, formed by dissolving PtCl 2 in solution of potash, and heating with alcohol. Both platinum black and platinum sponge are capable of condensing large quantities of gas, and act as indirect oxidants. 148 TEXT-BOOK OF CHEMISTRY Platinum is not oxidized by air or ; it combines directly with Cl, P, As, Si, S, and C ; is not attacked by acids, except aqua regia, in which it dissolves. It forms fusible alloys when heated with metals or reducible metallic oxides. It is attacked by mixtures liberating Cl, and by contact with heated phosphates, silicates, hydroxides, nitrates, or carbonates of the alkaline metals. Platinic Chloride Tetrachloride of platinum PtCl 4 337 When Pt is dissolved in aqua regia and the solution is evaporated, red, deliquescent crystals of hydrochloroplatinic acid, H 2 PtCl c , are obtained. These, when heated in chlorine, yield yellow, non-deli- quescent crystals of platinic chloride, PtCl 4 . Hydrochloroplatinic acid is a strong dibasic acid, the platinum being in the anion, which forms crystalline chloroplatinates with the alkaline metals, NH 4 , and a great number of nitrogenous organic bases. The formation of the K and NH 4 salts is utilized to test for those cations, and the forma- tion of the organic compounds is resorted to for the identification and analysis of these bases. CLASS V- BASYLOUS ELEMENTS. Elements whose Oxides unite with Water to form Bases; never to form Acids. Which form Oxysalts. The elements of this class are essentially basic and electropositive. In solutions of their compounds they never occur in an anion, simple or compound, but always constitute simple cations. I. SODIUM GROUP. Alkali Metals. LITHIUM SODIUM POTASSIUM RUBIDIUM CESIUM SILVER. Each of the elements of this group forms a single chloride, M'Cl, and one or more oxides, the most stable of which has the composition M' 2 0. They are, therefore, univalent. Their hydroxides, M'OH, are more or less alkaline and have markedly basic characters. Silver resembles the other members of the group in chemical properties, although it does not in physical characters. The name "alkali," first applied to "potash" from wood ashes (p. 160) is now used to designate substances which- are strongly basic, are alkaline in reaction, and saponify fats. The caustic alkalies are the hydroxides of K and Na, the carbonated alkalies are their car- bonates. Volatile alkali is ammonium hydroxide or carbonate. LITHIUM. Symbol=lA Atomic weight 1 (International^.^) Molecu- lar weight=USp. #r.=0.589. Occurrence. Widely distributed in small quantity,!; in many min- erals and mineral waters; in the ash of tobacco and other plants; in the milk and blood. Properties. A silver-white, ductile, volatile metal; the lightest of the solid elements; burns in air with a crimson flame; decomposes H 2 at ordinary temperatures, without igniting. Lithium Chloride. LiCl 42.5 crystallizes in deliquescent, regu- lar octahedra ; very soluble in H 2 and in alcohol. Lithium Bromide Lithii bromidum (U. S. P.) LiBr 87 is formed by decomposing lithium sulphate with potassium bromide; oi' by saturating a solution of HBr with lithium carbonate. It crystal- lizes in very deliquescent, soluble needles. 149 150 TEXT-BOOK OP CHEMISTRY Lithium Carbonate Lithii carbonas (U. S. P.) Li 2 C0 3 74 is a white, sparingly soluble, alkaline, amorphous powder. With uric acid it forms lithium urate, which is the most soluble of the urates of this class, and is therefore given to patients suffering from "the uric acid diathesis." Red. Orange. Yellow. Green. Blue. Cyan- blue. Violet. Tl. In. Ga 11 FIG. 16. 1, Solar spectrum; 10 and 11, Absorption spectra. Lithium bicarbonate LiHC0 3 68 is the salt which is present in lithia water. It is derived from the carbonate : Li 2 C0 3 +C0 2 +H 2 0=2LiHC0 8 Analytical Characters. (1) Ammonium carbonate: white ppt. in concentrated solutions; not in dilute solutions, or in presence of ammoniacal salts. (2) Sodium phosphate: white ppt. in neutral or alkaline solution ; soluble in acids and in solutions of ammoniacal SODIUM 151 salts. (3) It colors the Bunsen flame red; and exhibits a spectrum of two^ines A =6705 and 6102 (Fig. 16, No. 4, p. 150). SODIUM. Symbol=~Na (Natrium) Atomic weig~ht=23 (International^ 23.00) Molecular weight 46 Sp. gr.=0.972. Occurrence. As chloride, very abundantly and widely dis- tributed; also as carbonate, nitrate, sulphate, borate, etc. Preparation. By heating a mixture of dry sodium carbonate, chalk, and charcoal to whiteness in iron retorts: Na 2 C0 3 +2C=3CO+Na 2 It is now manufactured by the electrolysis of fused NaOH. Properties. A silver-white metal, rapidly tarnished, and coated with a yellow film in air. Waxy at ordinary temperatures; volatile at a white heat, forming a colorless vapor, which burns in air with a yellow flame. It oxidizes in air, and is usually preserved under naphtha. It burns with a yellow flame. It combines directly with Cl, Br, I, S, P, As, Pb and Sn. It decomposes water with evolution of hydrogen: Na 2 +2H 2 0=2NaOH-f H 2 . Because of this and other similar re- actions, metallic sodium, either as such or in the diluted form of sodium amalgam, is largely used to effect reductions. Oxides. Two oxides are known: Sodium monoxide Na 2 a grayish white mass; formed when Na is burnt in dry air, or by the action of Na on NaOH. Sodium dioxide Na 2 2 a white solid, formed when Na is heated in dry air to 200. Sodium dioxide, or peroxide, is now manufactured by oxidizing the fused metal in dry air or oxygen, and is used as a bleaching and oxidizing agent. It is a yellowish white, amorphous, very hygroscopic powder. If the temperature is kept low it dissolves in dilute acids, forming a strong solution of hydrogen dioxide: Na 2 2 +2HCl=2NaCl+H 2 2 . With water it produces a great elevation of temperature and liberates nascent oxygen: 2Na 2 2 +2H 2 0=4NaOH4-0 2 . With magnesium sulphate it forms magnesium dioxide, a non-alkaline oxidant : Na 2 2 + MgS0 4 =Na 2 S0 4 +Mg0 2 . Sodium Hydroxide Sodium hydrate Caustic Soda Sodium Hydroxidum (U. S. P. ) NaOH 40 is formed: (1) When H 2 is decomposed by Na; (2) by decomposing sodium carbonate by calcium hydroxide: Na 2 C0 3 +Ca(OH) 2 =C0 3 Ca+2NaOH (soda by lime); (3) in the same manner as in (2), using barium hydroxide in place of lime (soda by baryta). It frequently contains considerable quan- tities of As. It is an opaque, white, fibrous, brittle solid; fusible below red- ness; sp> r. 2.00; very soluble in H 2 0, forming strongly alkaline 152 TEXT-BOOK OF CHEMISTRY and caustic solutions, soda lye and liquor sodii hydroxidi, U. 8. P., (containing not less than 4.5 per cent, of NaOH). When exposed to air, solid or' in solution, it absorbs ILO and CO,, and is converted into carbonate. Its solutions attack glass. Sodium Chloride Common salt Sea salt Table salt Sodii chloridum (U. S. P.) NaCl 58.5 occurs very abundantly in nature, deposited in the solid" form as rock salt; in solution in all natural waters, especially in sea and mineral spring waters ; in sus- pension in the atmosphere; and as a constituent of almost all animal and vegetable tissues and fluids. It is formed in an infinite variety of chemical reactions. It is obtained from rock salt, or from the waters of the sea, or of saline springs; and is the source from which all the Na compounds are usually obtained, directly or indirectly. It crystallizes in anhydrous, white cubes, or octahedra ; xp, gr. 2.078; fuses at a red heat, and crystallizes on cooling; sensibly vola- tile at a white heat; quite soluble in H,0, the solubility varying but slightly with the variations of temperature. Dilute solutions yield almost pure ice on freezing. It is precipitated from concentrated solutions by HC1. It is insoluble in absolute alcohol; sparingly sol- uble in dilute spirit. It is decomposed by H.,S0 4 with formation of HC1 and sodium sulphate: 2NaCl+ H 2 S0 4 =2HCl+Na,S0 4 . Physiological salt solution (Liquor sodii chloridi physiologic us, U. S. P.) contains 8.5 gms. of NaCl in a liter of distilled water. Sodium Bromide Sodii bromidum (U. S. P.) NaBr 103 is formed by dissolving Br in solution of NaOH to saturation ;. evapo- rating; calcining at dull redness; redissolving, filtering, and crystal- lizing. It crystallizes in anhydrous cubes; quite soluble in ELO, soluble in alcohol. Sodium Iodide Sodii iodidum (U. S. P.) : NaI 150 is pre- pared by heating together H,0, Fe, and I in fine powder ; filtering ; adding an equivalent quantity of sodium sulphate, and some slaked lime, boiling, decanting and evaporating. Crystallizes in anhydrous cubes ; very soluble in H 2 ; soluble in alcohol. Sodium Nitrate Cubic or Chili saltpeter NaN0 3 85 occurs in natural deposits in Chili and Peru. It crystallizes in anhydrous, deliquescent rhombohedra; cooling and somewhat bitter in taste; fuses at 310; very soluble in H 2 0. Heated with H 2 SO 4 , it is de- composed, yielding HN0 3 and hydrosodic sulphate: H.,S0 4 -}-NaN03= HNaS0 4 -f UNO,. This reaction is that used for obtaining HN< ) . Sulphates. Monosodic Sulphate Ht/drosodic sulphate Add sodium sulphate Bisulphatc HNaS0 4 120 crystallizes in long, four-sided prisms; is unstable and decomposed by air, H 2 or alcohol, into H 2 S0 4 and Xa.,S0 4 . Heated to dull redness it is converted into sodium pyrosulphate, Na 2 So0 7 , corresponding to Nordhausen sul- phuric acid. Disodic Sulphate Sodium sulphate Neutral sodium sulphate SODIUM 153 Glauber's salt Sodii sulphas (U. S. P.) Na 2 S0 4 +Aq 142+18 occurs~in nature in solid deposits, and in solution in natural waters; It is obtained as a secondary product. in the manufacture of HCI, by the action of H 2 S0 4 on NaCl, the decomposition occurring according to the equation? 2NaCl+H 2 S0 4 =Na 2 S0 4 +2HCl, if the temperature is raised sufficiently. At lower temperatures, the monosodic salt is produced, with only half the yield of HCI: NaCl+H 9 SO 4 = NaHS0 4 +HCl. It crystallizes with 7 Aq, from saturated or supersaturated solu- tions at 5; or, more usually, with 10 Aq. As usually met with it is in large, colorless, oblique, rhombic prisms with 10 Aq; which effloresce in air, and gradually lose all their Aq. It fuses at 33 in its Aq, which it gradaully loses. If fused at 33 and allowed to cool, it remains liquid in supersaturated solution, from which it is deposited, the entire mass becoming solid, on contact with a small particle of solid matter. It dissolves in HCI with considerable diminution of temperature. Sodium Sulphite Na 2 S0 3 +7 Aq 126+126 is formed by pass- ing S0 2 over crystallized Na 2 C0 3 . It crystallizes in efflorescent, oblique prisms; quite soluble in H 2 0, forming an alkaline solution. It acts as a reducing agent. Sodium Thiosulphate Sodium hyposulphite Sodii thiosulphas (U. S. P.) Na 2 S 2 3 +5 Aq 158+90 is obtained by dissolving S in hot concentrated solution of Na 2 S0 3 , and crystallizing. It forms large, colorless, efflorescent prisms; fuses at 45; -very soluble in H 2 O, insoluble in alcohol. Its solutions precipitate alumina from solutions of Al salts, without precipitating Fe or Mn; they dissolve many compounds insoluble in H 2 ; cuprous hydroxide, iodides of Pb, Ag and Hg, sulphides of Ca and Pb. It is used in photography as a fixing bath, and is called "hypo"; it acts as a disinfectant and antiseptic; it is also employed in bleaching, to remove the chlorine. H 2 S0 4 decomposes Na 2 S 2 3 according to the equation : Na 2 S 2 3 +H 2 S0 4 =Na 2 S0 4 +S0 2 +S+H 2 and most other acids behave similarly. Oxalic, and a few otker acids, decompose the thiosulphate with formation of H 2 S as well as S0 2 and S. Silicates. Quite a number of silicates of Na are known. If silica and Na 2 C0 3 are fused together, the residue extracted with H;,0, and the solution evaporated, a transparent, glass-like mass, soluble in warm water, remains; this is soluble glass or water glass. Exposed to air in contact with stone, it becomes insoluble, and forms an impermeable coating. Phosphates. Trisodic Phosphate Basic sodium phosphate Na 3 P0 4 +12 Aq 164+216 is obtained by adding NaOH to disodic phosphate solution, and crystallizing. It forms six-sided prisms; 154 TEXT-BOOK OF CHEMISTRY quite soluble in H 2 0. Its solution is alkaline, and, on exposure to air, absorbs C0 2 , with formation of HNa 2 P0 4 and Na 2 C0 3 . Disodic Phosphate Sodium phosphate Hydro-disodic phosphate Neutral sodium phosphate Phosphate of soda Sodii phosphas (U. S. P.) HNa 2 P0 4 +12 Aq 142+216 is obtained by converting tricalcic phosphate into monocalcic phosphate, and decomposing that salt with sodium carbonate: Ca(P0 4 H 2 ) 2 +2Na 2 C0 3 =CaC0 3 +H 2 04-C0 2 +2HNa 2 P0 4 . Below 30 it crystallizes in oblique rhombic prisms, with 12 Aq; at 33 it crystallizes with 7 Aq. The salt with 12 Aq effloresces in air, and parts with 5 Aq ; and is very soluble in H 2 0. The salt with 7 Aq is not efflorescent, and less soluble in H 2 0. Its solutions are faintly alkaline. Monosodic Phosphate Acid sodium phosphate H 2 NaP0 4 + Aq 120-|-18 crystallizes in rhombic prisms ; forming acid solutions. At 100 it loses Aq ; at 200 it is converted into acid pyrophosphate, Na 2 H 2 P 2 7 ; and at 204 into the metaphosphate, NaP0 3 . Sodium Arsenites. The disodic arsenite, Na 2 HAs0 3 , is obtained as a viscous mass by fusing together 1 molecule of As 2 O 3 and 2 molecules of Na 2 CO 3 without contact of air. The monosodic arsenite, NaH 2 AsO 3 , is formed when an aqueous solution of Na 2 C0 3 is boiled with As 2 O 3 . By prolonged boiling this is converted into the pyroarsenite, Na 2 H 2 As 2 O 3 , and this into the metarsenite, NaAs0 2 , by progressive loss of water. Sodium arsenites exist in embalming liquids and are used in dyeing. Sodium Arsenates. The three arsenates, NaH 2 As0 4 , Na 2 HAs0 4 and Na a AsO 4 corresponding to the phosphates, are known, and are used in dyeing processes. Disodic Tetraborate Sodium pyroborate Borate of sodium Borax Sodii boras (U. S. P.) Na 2 B 4 7 +10 Aq 202+180 is prepared by boiling boric acid with Na 2 C0 3 and crystallizing: 4H 3 B0 3 +Na 2 C0 3 =C0 2 +6H 2 0+Na 2 B 4 7 It crystallizes in hexagonal prisms with 10 Aq; permanent in moist air, but efflorescent in dry air; or in regular octahedra with 5 Aq, permanent in dry air. Either form, when heated, fuses in its Aq, swells considerably; at a red heat becomes anhydrous; and, on cooling, leaves a transparent, glass-like mass. When fused it is capable of dissolving many metallic oxides, forming variously col- ored masses, hence its use as a flux and in blow-pipe analysis. Sodium Hypochlorite NaCIO 74.5 only known in solution Liquor sodae chlorinatae (U. S. P.) or Labarraque's solution obtained by decom- posing a solution of chloride of lime by Na 2 C0 3 . It is a valuable source of Cl, and is used as a bleaching and disinfecting agent. The pharmacopcrial prepara- tion should contain not less than 2.5 per cent, of available chlorine. Sodium Chlorate NaClO 3 l 06.5 is manufactured industrially by treating milk of lime with Cl. The solution of calcium chloride and chlorate so obtained SODIUM 155 is treated with Na 2 S0 4 , after removal of part of the CaCl 2 by concentration and cooling to 12. The NaC10 3 and NaCl formed are separated by taking advan- tage of the greater solubility of the former. NaClO 3 is soluble in its own weight of H 2 at 20. Sodium Permanganate NaMn0 4 142 prepared in the same way as the K salt (q. v.), which it resembles in its properties. It enters into the com- position of Condy's fluid, and of "chlorozone," which contains NaMnO 4 and NaClO. Sodium Acetate Sodii acetas (U. S. P. ) NaC 2 H 3 2 +3Aq 82+54 crystallizes in large, colorless prisms ; acid and bitter in taste ; quite soluble in H 2 O, soluble in alcohol; loses its Aq in dry air, and absorbs it again from moist air. It may be prepared by saturating acetic acid with sodium carbonate: 2C 2 HA+Na 2 C0 3 =H 2 0+C0 2 +2NaC 2 H 3 2 Heated with soda lime, it yields marsh gas. The anhydrous salt, heated with H 2 S0 4 , yields glacial acetic acid. Carbonates. Three are known: Na 2 C0 3 , HNaC0 3 , and H 2 Na 4 - (C0 3 ) 3 . Disodic Carbonate Sodium carbonate Neutral Carbonate Soda Sal soda Washing Soda Soda crystals Na 2 C0 3 + 10 Aq 106+180 industrially the most important of the Na compounds, is manufactured by Leblanc's or Solvay's processes; or from cryolite, a native fluoride of Na and Al. Leblanc's process, in its present form, consists of three distinct processes: (1) The conversion of NaCl into the sulphate, by decom- position by H 2 S0 4 . (2) The conversion of the sulphate into car- bonate, by heating a mixture of the sulphate with calcium carbonate and charcoal. The product of this reaction, known as black ball soda, is a mixture of sodium carbonate with charcoal and calcium sulphide and oxide. (3) The purification of the product obtained in (2). The ball black is broken up, disintegrated by steam, and lixiviated. The solution on evaporation yields the soda salt or soda of commerce. Of late years Leblanc's process has been in great part replaced by Solvay's method, or the ammonia process, which is more eco- nomical, and yields a purer product. In this process sodium chloride and ammonium bicarbonate react upon each other, with production of the sparingly soluble sodium bicarbonate, and the very soluble am- monium chloride. The sodium bicarbonate is then simply collected, dried, and heated, when it is decomposed into Na 2 C0 3 , H 2 0, and C0 2 . Sodium carbonate is also made from cryolite, a double fluoride of sodium and aluminium found in Greenland. This is heated with limestone when: Al 2 Na a F 12 +6CaC0 8 =6CaF 2 +6C0 2 +Na e Al 2 6 The sodium aluminate is extracted with water and the solution treated with carbon dioxide (obtained in the first reaction) when: Na 6 Al 2 6 +3H 2 0+3C0 2 =3Na 2 C0 3 +Al 2 (OH) 6 The monohydrated carbonate, Sodii carbonas monohydratus (U. 156 TEXT-BOOK OF CHEMISTRY S. P.), Na 2 C0 3 -|-H 2 is a white, crystalline, granular powder. It combines with and dissolves in H 2 with elevation of temperature. The crystalline sodium carbonate, Na 2 C0 3 -f-10Aq, forms large rhombic crystals, which effloresce rapidly in dry air; fuse in their Aq at 34; are soluble in H 2 0, most abundantly at 38. The solu- tions are alkaline in reaction. Sodium Bicarbonate Monosodic Carbonate Bicarbonate of ,soda Acid carbonate of soda Vichy salt Sodii bicarbonas (U. S. P.) NaHC0 3 84 exists in solution in many mineral waters. It is obtained by the action of C0 2 upon the disodic salt in the pres- ence of H 2 ; or, as above described, by the Solvay method. . It crystallizes in rectangular prisms, anhydrous and permanent in dry air. In damp air it gives off C0 2 , and is converted into the sesquicarbonate, Na 4 H 2 (C0 3 ) 3 . When heated it gives off C0 2 and H 2 0, and leaves the disodic carbonate. Quite soluble in water; above 70 the solution gives off C0 2 . The solutions are alkaline. Analytical Characters. (1) Hydrofluosilicic acid: gelatinous ppt., if not too dilute. (2) Potassium pyroantimonate, in neutral solution, and in absence of metals other than K and Li : a white, flocculent ppt.; becoming crystalline on standing. (3) Periodic acid in excess: white ppt., in not too dilute solutions. (4) Colors the Bunsen flame yellow, and shows a brilliant double line at A =5895 and 5889 (Fig. 16, No. 2, p. 150). POTASSIUM. Symbol = K (Kalium) Atomic weight = 39 (International = 39.10) Molecular weight=7SSp. gr.=0.865. Potassium silicates are widely distributed in rocks and minerals. The ash of plants contains about 10 per cent, of potassium carbonate, and this was formerly the chief source of the K compounds. Almost all of these are now derived from the deposits of carnallite: KC1, MgCl 2 +6Aq, and allied minerals at Stassfurt in Germany. It is prepared by a process similar to that followed in obtaining Na ; is a silver-white metal ; brittle at ; waxy at 15 ; fuses at 62.5 ; distils in green vapors at a red heat, condensing in cubic crystals. It is also obtained by electrolysis of fused KOH. It is the only metal which oxidizes at low temperatures in dry air. in which it is rapidly coated with a white layer of oxide or hydroxide. and frequently ignites, burning with a violet flame. It must, there- fore, be kept under naphtha. It decomposes H 2 0, or ice, witli great energy, the heat of the reaction igniting the liberated H. It com- bines with Cl with incandescence, and also unites directly with S, P, As, Sb, and Sn. Heated in C0 2 it is oxidized, and liberates C. Oxides. Three are known : K 2 ; K 2 2 ; and K 2 4 . Potassium Hydroxide Potassium hydrate Potash Potassa POTASSIUM 157 Caustic: Potash Common caustic Potassii hydroxidum (IT. S. P.) KOH 56 is obtained by processes similar to those used in manu- facturing NaOH. It is purified by solution in alcohol, evaporation and fusion in a silver basin, and* casting in silver moulds potash by alcohol; it is then free from KC1 and K 2 S0 4 , but contains small quantities of K 2 C0 3 , and frequently As. It is usually met with in cylindrical sticks, hard, white, opaque, and brittle. The KOH by alcohol has a bluish tinge, and a smoother surface than the common ; sp. gr. 2.1 ; fuses at dull redness ; is freely soluble in H 2 0, forming a strongly alkaline and caustic liquid; less soluble in alcohol. In air, solid or in solution, it absorbs H 2 and C0 2 , and is converted into K 2 C0 3 . Its solutions dissolve Cl, Br, I, S, and P. It decomposes the ammoniacal salts, with liberation of NH 3 ; and the salts of many of the metals, with formation of a K salt, and a metallic hydroxide. It dissolves the proteins, and, when heated, decomposes them with formation of leucin, tyrosin, etc. It oxidizes the carbohydrates with formation of potassium oxalate and carbonate. It decomposes the fats with formation "of soft soaps. Solution of potassium hydroxide (liquor potassii hydroxidi, U. S. P.) or liquor potassce, is an aqueous solution containing not less than 4.5 per cent of KOH. Liver of Sulphur Jiepar sulpliuris potassa sulphurata (U. S. P) is a mixture of K 2 S 3 and K 2 S 2 3 , and contains not less than 12.8 per cent, of sulphur. Potassium Chloride KC1 74.5 exists in nature, either pure or mixed with other chlorides; principally as carnallite, KC1, MgCl 2 +6 Aq. It crystallizes in anhydrous, permanent cubes, soluble in H 2 0. Potassium Bromide Potassii bromidum (U. S. P.) KBr 119 is formed either by decomposing FeBr 2 by K 2 C0 3 , or by dissolving Br in solution of KOH. In the latter case the bromate formed is converted into KBr, by calcination. It crystallizes in anhydrous cubes or tables; has a sharp, salty taste; very soluble in H 2 0, spar- ingly so in alcohol. It is decomposed by Cl with liberation of Br. Potassium Iodide Potassii iodidum (U. S. P.) KI 166 is obtained by saturating KOH solution with I, evaporating, and calcin- ing the resulting mixture of iodide and iodate with charcoal: 6KOH+3I 2 =3H 2 0+KI0 3 +5KI It frequently contains iodate and carbonate. It crystallizes in cubes, transparent if pure; permanent in air; anhydrous; soluble in H 2 and in alcohol. It is decomposed by Cl, HN0 3 and HN0 2 with liberation of I. It combines with other iodides to form double iodides. Its solutions dissolve iodine and many metallic iodides. Potassium Nitrate Nitre Saltpeter Potassii nitras (U. S. P.) 158 TEXT-BOOK OF CHEMISTRY KN0 3 101 occurs in nature, and is produced artificially, as a result of the decomposition of nitrogenized organic substances. It is usually obtained by decomposing native NaN0 3 by boiling solution of K 2 C0 3 or KC1. It crystallizes in six-sided, rhombic prisms, grooved upon the surface; soluble in H 2 0, with depression of temperature; more sol- uble in H 2 containing NaCl ; very sparingly soluble in alcohol ; fuses at 350 without decomposition; gives off 0, and is converted into nitrite below redness; more strongly heated, it is decomposed into N, 0, and a mixture of K oxides. It is a valuable oxidant at high temperatures. Heated with charcoal it deflagrates. Gunpowder is an intimate mixture of KN0 3 with S and C, in such proportion that the KN0 3 yields all the required for the combustion of the S and C. Potassium Hypochlorite KC10 90.5 is formed in solution by imperfect saturation of a cooled solution of KOH with hypochlorous acid. An impure solution is used in bleaching, and is known as Javelle water, which is the equivalent of the liquor potassae chlori- natae (U. S. P.) Potassium Chlorate Potassii chloras (U. S. P.) KC10 3 122.5 is prepared: (1) by passing Cl through a solution of KOH; (2) by passing Cl over a mixture of milk of lime and KC1, heated to 60; (3) by electrolysis of KC1. By electrolytic action the KC1 is split into its ions: 2KC1 2K+2C1 ; these, by secondary reactions with H 2 0, produce KC10: K 2 +2H 2 0=2KOH-f H 2 , and 2KOH+ C1 2 =2KC10+H,, and at the temperature generated, the KC10 yields KC10 3 : 2KC10+H 2 0=KC10 3 +KC1+H 2 . It crystallizes in trans- parent, anhydrous plates, soluble in H 2 ; sparingly soluble in weak alcohol. It fuses at 400 ; if further heated, it is decomposed into KC1 and perchlorate, and at a still higher temperature the perchlorate is decomposed into KC1 and : 2KC10 3 =KC10 4 +KC1+0 2 , and KC0 4 =KC1+20 2 . It is a valuable source of 0, and a more active oxidant than KN0 3 . When mixed with readily oxidizable substances, C, S, P, sugar, tannin, resins, etc., the mixtures explode when subjected to shock. With strong H 2 S0 4 it gives off C1 2 4 , an explosive yellow gas. It is decomposed by HN0 3 with formation of KN0 3 , KC10 4 , and libera- tion of Cl and 0. Heated with HC1 it gives off a mixture of Cl and C1 2 4 , the latter acting as an energetic oxidant in solutions in which it is generated. Sulphates. Dipotassic sulphate Potassium sulphate K,S0 4 174 occurs native; in the ash of many plants; and in solution in mineral waters. It may be prepared by the action of sulphuric acid on potassium carbonate : POTASSIUM 159 K 2 C0 3 +H 2 S0 4 =C0 2 +H 2 0+K 2 S0 4 . It crystallizes in right rhombic prisms; hard; permanent in air; salt and bitter in taste ; soluble in H 2 0. Monopotassic Sulphate. Hydropotassic sulphate Acid sulphate KHS0 4 136 is formed as a by-product in the manufacture of HN0 3 . When heated it loses H 2 0, and is converted into the pyro- sulphate, K S 7 , which, at a higher temperature, is decomposed into K 2 S0 4 and S0 3 . Dipotassic Sulphite Potassic sulphite K 2 S0 3 158 is formed by sat- urating solution of K 2 CO 3 with S0 2 , and evaporating over H 2 S0 4 . It crystallizes in oblique rhombohedra; soluble in H 2 0. Its solution absorbs from the air, with formation of K 2 S0 4 . Potassium Bichromate Bichromate of potassium K 2 Cr 2 7 294 is formed by heating a mixture of chrome iron ore with KN0 3 , or K 2 C0 3 in air; extracting with H 2 0; neutralizing with dilute H 2 S0 4 ; and evaporating. It forms large, reddish-orange colored prismatic crystals; soluble in H 2 0; fuses below redness, and at a higher temperature is decomposed into O, potassium chromate, and chromic oxide. Heated with HC1, it gives off Cl. Potassium Permanganate Potassii permanganas (U. S. P.) KMn0 4 158 is obtained by boiling a solution of potassium man- ganate with water: 3K 2 Mn0 4 +2H 2 0=Mn0 2 +4KOH+2KMn0 4 It crystallizes in dark prisms, almost black, with greenish reflec- tions, which, yield a red powder when broken. Soluble in H 2 0, communicating to it a red color, even in very dilute solution. It is a most valuable oxidizing agent. With organic matter its solution is turned to green, by the formation of the manganate, or deposits the brown sesquioxide of manganese, according to the nature of the or- ganic substance. In some instances the reaction takes place best in the cold, in others under the influence of heat ; in some better in acid solutions, in others in alkaline solutions. Mineral reducing agents act more rapidly. Its strong oxidizing powers render its solutions valuable as disinfectants. When used as a disinfectant it is split up as follows: 4KMn0 4 +2H 2 0=4Mn0 2 +4KOH+30 2 Potassium Acetate Potassii acetas (U. S. P) CH 3 .COOK 110 exists in the sap of plants ; and it is by its calcination that the major part of the carbonate of wood ashes is formed. It is prepared by neutralizing acetic acid with K 2 C0 3 or KHC0 3 : K 2 C0 3 +2CH 3 .COOH=C0 2 +H 2 0+2CH 3 .COOK It forms crystalline needles, deliquescent, and very soluble in H 2 ; less soluble in alcohol. Its solutions are faintly alkaline. Carbonates. Potassium Carbonate Dipotassic Carbonate Salt of tartar Pearl ash Potassii carbonas (U. S. P.) K 2 C0 3 160 TEXT-BOOK OF CHEMISTRY 138 exists in mineral waters, and in the animal economy. It is prepared industrially, in an impure form, known as potash or pearl- ash, from wood ashes, from the molasses of beet sugar, and from the native Strassfurt chloride. It is obtained pure by decomposing the monopotassic salt, purified by several recrystallizations, by heat: 2KHC0 3 =rC0 2 +H 2 0+K 2 C0 3 or by calcining a potassium salt of an organic acid. Thus cream of tartar, mixed with nitre and heated to redness, yields a black mixture of C and K 2 C0 3 , called black flux; on extracting which with H 2 0, a pure carbonate, known as salt of tartar, is dissolved. Anhydrous, it is a white, granular, deliquescent, very soluble pow- der. At low temperatures it crystallizes with 2Aq. Its solution is alkaline. Monopotassic Carbonate Hydropotassic carbonate Potassium bicarbonate Potassii bicarbonas (U. S. P) HKC0 3 100 is ob- tained by dissolving K 2 C0 3 in H 2 0, and saturating the solution with C0 2 : K 2 C0 3 +C0 2 +H 2 0=2KHC0 3 It crystallizes in oblique rhombic prisms, much less soluble than the carbonate. In solution, it is gradually converted into the dipotassic salt when heated, when brought into a vacuum, or when treated with an inert gas. The solutions are alkaline in reaction and in taste, but are not caustic. The substance used in baking, under the name salaeratus, is this or the corresponding Na salt, usually the latter. Its extensive use in some parts of the country is undoubtedly in great measure the cause of the prevalence of dyspepsia. When used alone in baking, it "raises" the bread by decomposition into carbon dioxide and dipo- tassic (or disodic) carbonate, the latter producing disturbances of digestion by its strong alkaline reaction. Monopotassic Oxalate KHC 2 O 4 128 forms transparent, soluble, acid needles. It occurs along with the quadroxalate HKC 2 O 4 , H 2 C 2 O 4 -f-2Aq, in salt of lemon or salt of sorrel, used in straw bleaching, and for the removal of ink-stains, etc. It closely resembles Epsom salt in appearance, and has been fatally mistaken for it. Tartrates. Dipotassic Tartrate Potassium tartrate Soluble tartar Neutral tartrate of potash K 2 C 4 H 4 226 is prepared by neutralizing the hydropotassic salt with potassium carbonate: K 2 C0 3 +2KHC 4 H 41 6 =C0 2 +H 2 0+2K 2 C 4 H 4 6 . It forms a white, crystalline powder, very soluble in H 2 0, the solution being dextrogyrous, [a] D = -(-28.48 ; soluble in alcohol. Acids, even acetic, decompose its solution, with precipitation of the monopotassic salt. POTASSIUM 161 The constitution and relation of the tartrates may be seen by a study of their graphic formulae : COOH COOK CHOH CHOH CHOH CHOH COOH COOH COOK COONa COO(SbO) CHOH CHOH CHOH CHOH CHOH CHOH COOK COOK COOK Dipotassic Sodium and Antimonyl- Tartrate Potassium Tartrate Potassium Tartrate Tartaric Acid Monopotassic Tartrate Monopotassic Tartrate Hydropotassic tartrate Cream of tar- tar Potassii bitartras (U. S. P.) Acid potassium tartrate Po- tassium bitartrate HKC 4 H 4 188. During the fermentation of grape juice, as the proportion of alcohol increases, crystalline crusts collect in the cask. These constitute the crude tartar, or argol, of commerce, which is composed, in great part, of monopotassic tartrate, with some calcium tartrate and coloring matter. The crude product is purified by repeated crystallization from boiling H 2 0, decolorizing with animal charcoal, digesting the purified tartar with HC1 at 20, washing with cold H 2 0, and crystallizing from hot H 2 0. It crystallizes in hard, opaque (translucent when pure), rhombic prisms, which have an acidulous taste, and are very sparingly soluble in H 2 0, still less soluble in alcohol. Its solution is acid, and dis- solves many metallic oxides with formation of double tartrates. When boiled with antimony trioxide, it forms tartar emetic. It is used in the household, combined with monosodie carbonate, in baking, the two substances reacting upon each other to form Rochelle salt, with liberation of carbon dioxide. Baking Powders are now largely used as substitutes for yeast to " raise " biscuits, cakes, etc. Their action is based upon the decomposition of HNaCO 3 by some salt having an acid reaction, or by a weak acid. In addition to the bicarbonate and flour, or cornstarch (added to render the bulk convenient to handle and to diminish the rapidity of the reaction), they contain cream of tartar, tartaric acid, alum, or acid phosphates. Some of the reactions by which the C0 2 may be liberated are: + C0 2 Carbon dioxide -f 2C0 2 Carbon dioxide 6NaHCO 3 = K 2 SO 4 -f 3Na 2 S0 4 -f- Monosodic Dipotassic Disodic carbonate. sulphate. sulphate. (1) HKC 4 H 4 O a -f Monopotassic tartrate. NaHC0 3 Monosodie carbonate. = NaKC 4 H 4 6 Sodium potassium tartrate. + H *0 Water. (2) H 2 C 4 H 4 6 + Tartaric acid. 2NaHCO 3 Monosodie carbonate. = Na 2 C 4 H 4 O 6 . Disodic tartrate. 4- 2H 2 Water. (3) A1 2 (S0 4 ) 3 ,K 2 S0 4 Aluminium potassium alum. -+- A1 2 6 H 6 -f 6C0 2 Aluminium Carbon hydroxide. dioxide. (4) A1 2 (S0 4 ) 3 -f 6NaHC0 3 = 3Na 2 S0 4 -f A1 2 6 H 6 -f 6C0 2 Aluminium Monosodie Disodic Aluminium Carbon sulphate. carbonate. sulphate. hydroxide. dioxide. 162 TEXT-BOOK OF CHEMISTRY Sodium Potassium Tartrate Rochelle salt Potassii et sodii tartras (U. S. P.) NaKC 4 H 4 6 +4Aq 210+72 is prepared by saturating monopotassic tartrate with disodic carbonate. It crystal- lizes in large, transparent prisms, which effloresce superficially in dry air and attract moisture in damp air. It fuses at 70-80, and loses 3Aq at 100. It is soluble in 1.4 parts of cold H,0. Potassium Antimonyl Tartrate Tartrated antimony Tartar emetic Antimonii et potassii tartras (U. S. P.) (SbO)KC 4 H,0 6 + i/ 2 Aq 331.6 is prepared by boiling a mixture of 3 pts. Sb 2 3 and 4 pts. HKC 4 H 4 6 in H,0 for an hour, filtering, and allowing to crystallize : 2KHC 4 HA+SbA=H 2 0+2(SbO)K.C 4 H 4 O fl It crystallizes in transparent, soluble, right rhombic octahedra, which turn white in air. Its solutions are acid in reaction, have a nauseating metallic taste, and are precipitated by alcohol. The crys- tals contain l / 2 Aq, which they lose entirely at 100, and, partially by exposure to air. It is decomposed by the alkalies, alkaline earths, and alkaline carbonates, with precipitation of Sb 2 3 . The precipi- tate is redissolved by excess of soda or potash, or by tartaric acid. HC1, H 2 S0 4 and HN0 3 precipitate corresponding antimonyl com- pounds from solutions of tartar emetic. It converts mercuric into mercurous chloride. It forms double tartrates with the tartrates of the alkaloids. Potassium Cyanide. KCN 65 is obtained by heating a mix- ture of potassium ferrocyanide and dry K 2 C0 3 , as long as efferves- cence continues; decanting and crystallizing: K 4 Fe(CN) 6 +K 2 C0 3 =KCNO+Fe+C0 2 +5KCN It is usually met with in dull, white, amorphous masses. Odorless when dry, it has the odor of hydrocyanic acid when moist. It is deli- quescent, and very soluble in H 2 ; 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.v.). Potassium Ferrocyanide Yellow prussiate of potash K 4 Fe ( CN ) a -f 3 Aq 368-f-54. This salt, the source of the other cyanogen compounds, is manufactured by adding nitrogenous organic matter (blood, bones, hoofs, leather, etc.) and iron to K 2 CO 3 in fusion; or by other processes in which the N is obtained from the residues of the purification of coal gas, from atmos- pheric air, or from ammoniacal compounds. It forms soft, flexible, lemon-yellow crystals, permanent in air at ordinary temperatures. They begin to lose Aq at 60, and become anhydrous at 100. Soluble in H 2 0; insoluble in alcohol, which precipitates it from its aqueous solution. When calcined with KOH or K,('() :I potassium cyanide and cyanate CESIUM AND RUBIDIUM 163 are formed, and Fe is precipitated. Heated with dilute H 2 S0 4 , it yields an insoluble white or blue salt, potassium sulphate, and hydrocyanic acid. Its solutions form, with those of many of the metallic salts, insoluble f errocyanides ; 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 Red prussiate of potash K 3 Fe(CN) 6 329 is prepared by acting upon the ferrocyanide with chlorine; or, better, by heating the white residue of the action of H 2 S0 4 upon potassium ferrocyanide, in the preparation of hydrocyanic acid, with a mixture of 1 vol. HN0 3 and 20 vols. H 2 O; the blue product is digested with H 2 O, 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 dark blue precipitate, Turnbull's blue. Analytical Characters. (1) Platinic chloride, in presence of HC1: yellow ppt, K 2 PtCl 6 ; crystalline if slowly formed; sparingly soluble in H 2 0, much less so in alcohol. (2) Tartaric acid in not too dilute solution: white ppt.; soluble in alkalies and in concentrated acids. (3) Hydrofiuosilicic acid: translucent, gelatinous ppt.; forms slowly; soluble in strong alkalies. (4) Perchloric acid: white ppt.; sparingly soluble in H,0; insoluble in alcohol. (5) Phosphomolyb- dic acid: white ppt.; forms slowly. (6) Colors the Bunsen flame violet (the color is only observable through blue glass in the presence of Na), and exhibits a spectrum of two bright lines: A =7860 and 4045 (Fig. 16, No. 3, p. 150). Action of the Sodium and Potassium Compounds on the Economy. The hydroxides of Na and K, and in a less degree the carbonates, disintegrate 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, consequent upon inflammation. The treatment consists in the neutralization of the alkali by an acid, dilute vinegar. Neutral. 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 is not poisonous, are without deleterious action, unless taken in excessive quantity. Common salt has pro- duced 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 dyspnea, convulsions, arrest of the heart's action, and death. In the adult human subject, death has followed the ingestion of doses of 15-30 gms. of the nitrate, in several instances; doses of 8-60 gms. of the sulphate have also proved fatal. CAESIUM AND RUBIDIUM. Caesium Symbol = Cs Atomic weight = 133 (International^ 132.81; and Rubidium Symbol=Itb Atomic weig~ht=85 Inter- rwMaZ=85.45) ; are two rare elements, discovered in 1860 by Kirch- 164 TEXT-BOOK OP CHEMISTRY off and Bunsen while examining spectroscopically the ash of a spring water. They exist in very small quantity in lepidolite. They combine with and decompose H 2 even more energetically than does K, forming strongly alkaline hydroxides. SILVER. Symbol=:Ag (Argentum) Atomic weight 108 (International =107.88) Molecular w eight =216 S p. 0r.=10.4-10.54. 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. Silver occurs free in nature, also in combination as the sulphide or chloride; it is frequently contained in other sulphides, notably those of Sb, Pb, and Cu. When pure Ag is required, coin silver is dissolved in HNO :} and the diluted 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 2 S0 4 in a plati- num basin, with a bar of pure Zn, and washing thoroughly, after complete reduction; or (2) by mixing it with chalk and charcoal (AgCl, 100 parts; C, 5 parts; CaC0 3 , 70 parts), and gradually intro- ducing 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 2 S. It combines directly with Cl, Br, I, S, P, and As. Hot H 2 S0 4 dissolves it as sul- phate, and HN0 3 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. Silver seems to exist in a number of allotropic modifications, be- sides that in which it is ordinarily met with. In one of these it is brilliant, metallic, bluish green in color, and dissolves in H 2 0, form- ing a deep red solution in another it has the color of burnished gold, when dry ; and in still another it has also a bluish green color, but is insoluble in water. Very dilute mineral acids immediately convert these modifications into normal gray silver, without evolution of any gas. Oxides. Three oxides of silver are known: Ag 4 0, Ag.,0, and Ag 2 2 . Silver Monoxide Argenti oxidum (U. S. P.) Ag,0 232 formed by precipitating a solution of silver nitrate with potash: 2AgN0 3 +2KOH=2KN0 3 +H 2 0+Ag 2 It is a brownish powder; faintly alkaline and very slightly AMMONIUM COMPOUNDS 165 soluble in HoO ; strongly basic. It readily gives up its oxygen. On contact with ammonium hydroxide it forms a fulminating powder. Silver Chloride AgCl 143.5 formed when HC1 or a chloride is added to a solution containing silver. It is white; turns violet and black in sunlight; volatilizes at 260; sparingly soluble in HC1; soluble in solutions of the alkaline chlorides, thiosulphates, and cyanides, and in ammonium hydroxide. It crystal- lizes in octahedra on exposure of its ammoniacal solution. Silver Bromide AgBr and Iodide Agl are yellowish precipitates, formed by decomposing silver nitrate with potassium bromide and iodide. The former is very sparingly soluble in ammonium hydroxide, the latter is insoluble. Silver Nitrate Argenti nitras (U. S. P.) AgN0 3 170 is prepared by dissolving Ag in HN0 3 , evaporating, fusing, and re- crystallizing. It crystallizes in anhydrous, right rhombic plates; soluble in H 2 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 caustic, lapis infernalis; argenti nitras fusus (U. S. P.). If, during fusion, the temperature is raised too high, it is converted into nitrite, 0, and Ag ; and if sufficiently heated leaves pure Ag. Dry Cl and I decompose it, with liberation of anhydrous HN0 3 . It absorbs NH 3 , to form a white solid, AgN0 3 , 3NH 3 , which gives up its NH 3 when heated. Its solution is decomposed very slowly by H, with deposition of Ag. Analytical Characters. (1) Hydrochloric acid: white flocculent ppt. ; soluble in NH 4 OH; insoluble in HN0 3 . (2) Potash or soda: brown ppt.; insoluble in excess; soluble in NH 4 OH. (3) Ammonium hydroxide, from neutral solutions : brown ppt. ; soluble in excess. (4) Hydrogen sulphide or ammonium sulphydrate : black ppt. insoluble in NH 4 HS. (5) Potassium bromide: yellowish white ppt.; insoluble in acids, if not in great excess; soluble in NH 4 OH. (6) Potassium iodide : same as KBr, but the ppt. is less soluble in NH 4 OH. 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 HNO 3 , 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 is seen before the symptoms of corrosion are far advanced, emetics. AMMONIUM COMPOUNDS. The Ammonium Theory. Although neither the radical ammo- nium, NH 4 , nor the molecule (NH 4 ) 2 has ever been isolated, the existence of the radical in the ammoniacal compounds is almost uni- 166 TEXT-BOOK OF CHEMISTRY versally admitted. The ammonium hypothesis is based chiefly upon the following facts: (1) the close resemblance of the ammoniacal 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 ammonium salt; (3) when solutions of the ammoniacal salts are subjected to electrolysis, a mixture, having the composition NH 3 -fH is given off at the negative pole; (4) amalgam of sodium, in contact with a concentrated solution of ammonium chloride, increases much in volume, and is converted into a light, soft mass, having the luster of mercury. This ammonium amalgam is decomposed gradually, giving off ammonia and hydrogen in the proportion NH 3 +H; (5) if the gases NH 3 +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 com- bination, the H would exhibit the more energetic affinities of an element in the nascent state. The hydrogen so liberated is in the nascent state. Ammonium Hydroxide Caustic ammonia NH 4 OH 35 has never been isolated, probably owing to its tendency to decomposition ; NH 4 OH=NH 3 -}-H 2 0. It is considered as existing in the so-called aqueous solutions of ammonia. These are colorless liquids; of less sp. gr. than H 2 ; 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 am- moniae and Aqua ammonias fortior (U. S. P.) are such solutions; the former contains about 10 per cent, and the latter 28 per cent, of NH 3 . Ammonium Hydrogen Sulphide Ammonium Sulphydrate N 4 HS 51 is formed, in solution by saturating a solution of NH 4 HO with H 2 S; or, an- hydrous, by mixing equal volumes of dry NH 3 and dry H 2 S. The anhydrous compound is a colorless, transparent, volatile and soluble solid. The solution, when freshly prepared, is colorless, but soon becomes yellow from oxidation, and formation of ammonium disulphide and thiosulphate, and finally deposits sulphur. The sulphides and hydrosulphide of ammonium are also formed during the decomposition of protein bodies, and exist in the gases formed in burial vaults, sewers, etc. Ammonium Chloride Sal ammoniac Ammonii chloridum (U. S. P) NH 4 C1 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 H.,O. Its solution is neutral, but loses NH 3 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 COMPOUNDS 167 Ammonium Bromide Ammonii bromidum (U. S. P.) (NH 4 )Br 98 is formed either by combining NH 3 and HBr; by decomposing ferrous bromide with NH 4 OH; or by double decomposition between KBr and (NH 4 ) 2 SO 4 . It is a white, granular powder, or crystallizes in large prisms, which turn yellow on exposure to air; quite soluble in H 2 O; volatile without decomposition. Ammonium Iodide Ammonii iodidum (U. S. P.) NHJ 145 is formed by union of equal volumes of NH 3 and HI; or by double decomposition of KI and (NH 4 ) 2 S0 4 . It crystallizes in deliquescent, very soluble cubes. Ammonium Nitrate (NH 4 )N0 3 80 is prepared by neutralizing HN0 3 with ammonium hydroxide or carbonate. It crystallizes in flexible, anhydrous, six-sided prisms; very soluble in H 2 O, with considerable diminution of tem- perature; fuses at 150, and decomposes at 210, with formation of nitrous oxide: (NH 4 )NO 3 =:N 2 0-f 2H 2 O. If the heat is suddenly applied, or allowed to surpass 250, NH 2 , NO. and N 2 are formed. When fused it is an active oxidant. Sulphates. Diammonic Sulphate Ammonic sulphate (NH 4 ) 2 S0 4 132 is obtained by collecting the distillate from a mixture of ammoniacal gas liquor and lime in H 2 S0 4 . It forms anhydrous, soluble, rhombic crystals; fuses at 150, and is decomposed at 200 into NH 3 and H(NH 4 )S0 4 . Monoammonic Sulphate Hydroammonic sulphate Bismuth of ammonia H(NH 4 )S0 4 115 is formed by the action of H 2 S0 4 on (NH 4 ) 2 SO 4 . It crystal- lizes in right rhombic prisms, soluble in H 2 and in alcohol. Ammonium Acetate (NH 4 )C 2 H 3 2 77 is formed by saturating acetic acid with NH 3 , or with ammonium carbonate. It is a white, odorless, very soluble solid; fuses at 86, and gives off NH 3 ; then acetic acid, and finally acetamide. Liquor ammonii acetatis (U. S. P. )=Spirit of Minderus is an aqueous solution of this salt, containing not less than 7 per cent, of ammonium acetate. Ammonium Sesquicarbonate Ammonium Carbonate Sal vola- tilePreston salts Ammonii carbonas (U. S. P.) ; NH 4 HC0 3 + NH 4 C0 2 NH 2 157 is prepared by heating a mixture of NH 4 C1 or (NH 4 ) 2 S0 4 and chalk, and condensing the product. It crystallizes in rhombic prisms; has an ammoniacal odor and an alkaline reaction; soluble in H 2 0. By exposure to air or by heating its solution, it is decomposed into H 2 0, NH 3 , and H(NH 4 )C0 3 . It is not a pure salt, but a mixture of monoammonium carbonate and ammonium car- bamate. Analytical Characters. (1) Entirely volatile at high tempera- tures. (2) Heated with KOH, the ammoniacal compounds give off NH 3 , recognizable: (a) by changing moist red litmus to blue; (&) by its odor; (c) by forming a white cloud on contact with a glass rod moistened with HC1. (3) With platinic chloride: a yellow, crystal- line ppt. Action on the Economy. Solutions of the hydroxide and carbonate act upon animal tissues in the same way as the corresponding Na and K compounds. They, moreover, disengage NH 3 , which causes intense dyspnea, irritation of the air-passages, 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 administered by in- halation. 168 TEXT-BOOK OF CHEMISTRY II. THALLIUM GROUP. THALLIUM. -Symbol=Tl Atomic weight 2Q^ (International 2^.^ Sp. A rare element, first obtained from the deposits in flues of sul- phuric 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 resem- bles the alkali metals in being readily oxidized, in forming alums, and informing no acid hydrate. It differs from the alkali metals in the thallic compounds, which contain TT". It is characterized spectro- scopically by a bright green line A=5349. III. 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 M0 2 ; each forms a hydroxide, having well-marked basic characters. CALCIUM. Symbol=Csi Atomic weight=40 (International=40.01) Mo- lecular weight=SOSp. #r.=1.984. Occurs only in combination, as limestone, marble, chalk (CaC0 3 ), gypsum, selenite, alabaster (CaSOJ, and many other minerals. In bones, egg-shells, oyster-shells, etc., as Ca 3 (P0 4 ), and CaC0 3 , and in many vegetable structures. The element is obtained by electrolysis of fused CaCL, or by heat- ing CaI 2 with Na. It is a hard, yellow, very ductile, and malleable metal, fusible at a red heat; not sensibly volatile. In dry air it is not altered, but is converted into CaHo0 2 in damp air; decomposes H 2 ; burns when heated in air. ~ Calcium Oxide Quick Lime Lime Calx (U. S. P.) CaO 56 is prepared by heating a native carbonate (limestone) ; or, when required pure, by heating a carbonate, prepared by precipitation: CaC0 3 =CaO+C0 2 CALCIUM 169 It occurs in white or grayish, amorphous masses; odorless; alka- line, caustic; almost infusible; sp. gr. 2.3. With H 2 it gives off great neat and is converted into the hydroxide (slaking). In air it becomes air-slaked, falling into a white powder, having the com- position CaC0 3 , CaH,0 2 . Calcium Hydroxide Calcium Hydrate Slaked lime Ca(OH)., 74 is formed by the action of H 2 on CaO. If the quantity of H 2 used be one-third that of the oxide, the hydroxide remains as a dry, white, odorless powder; alkaline in taste and reaction; more soluble in cold than in hot H,0. If the quantity of H 2 is greater, a creamy or milky liquid remains, cream, or milk of lime; a solu- tion holding an excess in suspension. With a sufficient quantity of H 2 the hydroxide is dissolved to a clear solution, which is lime water Liquor calcis (U. S. P.). The solubility of Ca(OH) 2 is diminished by the presence of alkalies, and is increased by sugar or mannite. Solutions of Ca(OH) 2 absorb C0 2 with formation of a white deposit of CaC0 3 . Calcium Carbide CaC 2 is formed by the action of a very high temperature upon a mixture of quick lime and carbon. It is an amorphous grayish substance, which is decomposed by water, yielding acetylene gas: CaC 2 +2H 2 0=C 2 H 2 +Ca(OH) 2 . One kilo. CaC 2 yields 440 litres C 2 H 2 . Calcium Chloride Calcii chloridum (U. S. P.) CaCl 2 111 is obtained by dissolving marble in HC1: CaC0 3 +2HCl=CaCl 2 +H 2 0+C0 2 It is bitter, deliquescent, very soluble in H0 2 ; crystallizes with 6Aq, which it loses when fused, leaving a white, amorphous mass, used as a drying agent. Chlorinated Lime Chloride of Lime Bleaching powder Calx chlorinata (U. S. P.) is a white or yellowish, hygroscopic powder, prepared by passing Cl over Ca(OH) 2 , maintained in excess. It is bitter and acrid in taste ; soluble in cold H 2 ; decomposed by boiling H 2 0, and by the weakest acids, with liberation of CL It is decom- posed by C0 2 , with formation of CaC0 3 , and liberation of hypo- chlorous acid, if it be moist ; or of Cl, if it be dry. A valuable dis- infectant. The "available chlorine" is the amount liberated by acids, and should be not less than 30 per cent. Bleaching powder was formerly considered as a mixture of calcium chloride and hypochlorite, formed by the reaction: 2CaO-}-2Cl 2 = CaCL+Ca(C10) 2 , but it is more probable that it is a definite com- pound having the formula CaCl(OCl), which is decomposed by H 2 into a mixture of CaCl 2 and Ca(C10) 2 ; and by dilute HN0 3 or H 2 S0 4 with formation of HC10. Calcium Sulphate CaS0 4 136 occurs in nature as anhydrite; and with 2Aq in gypsum, alabaster, selenite; and in solution in 170 TEXT-BOOK OF CHEMISTRY natural waters. Terra alba is ground gypsum. It crystallizes with 2Aq in right rhombic prisms ; sparingly soluble in H 2 0, more soluble in H 2 containing free acids or chlorides. When the hydrated salt (gypsum) is heated to 80, or, more rapidly, between 120-130, 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 H 2 O, 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 septic germs, and cannot be thoroughly purified by disinfectants. 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. Calcium Phosphate Tricalcic Phosphate Tribasic or neutral phosphate Bone Phosphate Phosphate of Lime Ca 3 (P0 4 ) 2 310 occurs in nature, in soils, guano, coprolites, phosphorite, in all plants, and in every animal tissue and fluid. It is obtained by dis- solving bone-ash in HC1, filtering, and precipitating with NH 4 OH; or by double decomposition between CaCl, and an alkaline phosphate. When freshly precipitated it is gelatinous; when dry, a light, white, amorphous powder ; almost insoluble in pure H 2 ; soluble to a slight extent in H 2 containing ammoniacal salts, or NaCl or NaN0 3 ; readily soluble in dilute acids, even in H 2 charged with carbonic acid. It is decomposed by H,S0 4 into CaS0 4 and Ca(H 2 P0 4 ) 2 . Bone-ash is an impure form of Ca 3 (P0 4 ) 2 , obtained by calcining bones, and used in the manufacture of P and of superphosphate. Calcium Carbonate CaC0 3 100 the most abundant of the natural compounds of Ca, exists as limestone, calcspar, chalk, marble, Iceland spar, and arragonite; and forms the basis of corals, shells of Crustacea and of molluscs, etc. Otoliths, which occur in the internal ear, parotid calculi, and sometimes vesical calculi consist of CaC0 3 . Precipitated chalk Calcii carbonas praecipitatus (U. S. P.) is prepared by precipitating a solution of CaCl 2 with one of Na 2 C0 3 . Prepared chalk Creta praeparata (U. S. P.) is native chalk, puri- fied by grinding with H 2 0, diluting, allowing the coarser particles to subside, decanting the still turbid liquid, collecting and drying the finer particles. Such a process is known as elutriation or levi- gation. It is a white powder, almost insoluble in pure H 2 0; much more soluble in H 2 containing carbonic acid, the solution being regarded as containing monocalcic carbonate, H 2 Ca(C0 3 ) 2 . At a red heat it yields CO., and CaO. It is decomposed by acids with liberation of C0 2 . Calcium Oxalate Oxalate of lime CaC 2 4 128 exists in the sap of many plants, in human urine, and in mulberry calculi, and is BARIUM 171 formed a*s a white, crystalline precipitate, by double decomposition, between a Ca salt and an alkaline oxalate. It is insoluble in H 2 0, acetic acid, or NH 4 OH; soluble in the mineral acids and in solution of H 2 NaP0 4 . Analytical Characters. (1) Ammonium sulphydrate: nothing, unless the Ca salt be the phosphate, 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 HN0 3 . (4) Sulphuric acid : white ppt., either immediately or on dilution with three volumes of alcohol; very sparingly soluble in H 2 0, insoluble in alcohol; sol- uble in sodium thiosulphate solution. (5) Sodium tungstate: dense white ppt., even from dilute solutions. (6) Colors the flame of the Bunsen burner reddish-yellow, and exhibits 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 = Sr Atomic weight = 87.5 (International = 87.63) Sp. #r.=2.54. An element not as abundant as Ba, occurring principally in the minerals strontianite (SrCo 3 ) and celestine (SrSOJ. Its compounds resemble those of Ca arid Ba. Its nitrate is used in making red fire. The bromide, iodide, and the salicylate are official in the U. S. P. Analytical Characters. (1) Behaves like Ba with alkaline car- bonates and Na 2 HP0 4 . (2) Calcium sulphate: a white ppt., which forms slowly; accelerated by addition of alcohol. (3) The Sr com- pounds color the Bunsen flame red-, or, as observed through blue glass, purple or rose color. The Sr flame gives a spectrum of many bands, of which the most prominent are : \ =6694, 6664, 6059, 6031, 4607. BARIUM. $i/m&0Z=Ba Atomic weight=137 (International=~[.37.37) Mo- lecular weight=214: Sp. gr.=4.0. Occurs only in combination, principally as heavy spar (BaSOJ and witherite (BaC0 3 ). It is a pale yellow, malleable metal, quickly oxidized in air, and decomposing H 2 at ordinary temperatures. Oxides. Barium Monoxide Baryta BaO 153 is prepared by calcining the nitrate: 2Ba(N0 3 ) 2 =4N0 2 +0 2 +2BaO It is a grayish-white or white, amorphous, caustic solid. In air it absorbs moisture and C0 2 , and combines with H 2 as does CaO. 172 TEXT-BOOK OF CHEMISTRY Barium Dioxide Ba0 2 169 is prepared by heating the monoxide in 0. It is a grayish-white, amorphous solid. Heated in air it is decomposed : BaO,=BaO+0. Aqueous acids dissolve it with formation of a barytic salt and H 2 2 . Barium Hydroxide Ba(OH) 2 171 is prepared by the action of H 2 on BaO. It is a white, amorphous solid, soluble in H 2 0. Its aqueous solution, baryta water, is alkaline, and absorbs C0 2 , with formation of a white deposit of BaC0 3 . Barium Chloride BaCl 2 +2 Aq 208+36 is obtained by treat- ing BaS or BaC0 3 with HC1. It crystallizes in prismatic plates, per- manent in air, soluble in H 2 0. Barium Nitrate Ba(N0 3 ) 2 261 is prepared by neutralizing HN0 3 with BaCO 3 . It forms octahedral crystals, soluble in H 2 0. Barium Sulphate BaS0 4 233 occurs in nature as heavy spar, and is formed as an amorphous, white powder, insoluble in acids, by double decomposi- tion between a Ba salt and a sulphate in solution. It is insoluble in H 2 O and in acids. It is used as a pigment, permanent white. Barium Carbonate BaCO 3 197 occurs in nature as icitherite, 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 2 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 HN0 3 . (4) Colors the Bunsen flame greenish -yellow, and ex- hibits a spectrum of several lines, the most prominent of which are: A=6108, 6044, 5881, 5536. Action on the Economy. The oxides and hydroxide act as corrosives, by virtue of their 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 sulphides, followed by emetics, are indicated as antidotes. The sulphate, notwithstanding its insolubility in water, is poisonous to some animals. IV. MAGNESIUM GROUP. MAGNESIUM ZINC CADMIUM. Each of these elements forms a single oxide a corresponding basic hydroxide, and a series of salts in which its atoms are bivalent. The existence of potassium zincate, Zn0 2 K 2 , obtainable by the action of zinc hydroxide and potassium hydroxide upon each other: Zn(OH) 2 +2KOH=Zn0 2 K 2 +2H 2 would seem to require the trans- ferral of zinc to the amphoteric class; the Zn(OH) 2 in the above re- action fulfilling the requirements of the second definition of acids (see p. 178). Potassium zincate should, however, be considered rather MAGNESIUM 173 as a double oxide of zinc and potassium: ZnOK,0 or Zn.OK.OK, than as a true salt for the following reasons: (1) It is also produced by the reaction : Zn+2KOH:=Zn0 2 K 2 +H 2 , in which, if Zn0 2 K 2 be a salt, KOH, the most distinctly basic substance known, must be considered to be an acid. (2) In the electrolysis of Zn0 2 K 2 the Zn and K go to the negative pole, and the to the positive, while in the electrolysis of true ternary salts, such as K 2 S0 4 , the oxygen accom- panies the other electro-negative element to the positive pole, the metal going alone to the negative. Moreover, the zincates are un- stable bodies, and the most prominent function of Zn(OH) 2 is that of a base, as in the reaction Zn(OH) 2 +H 2 S0 4 =ZnS0 4 +2H0 2 . (See Aluminium, p. 178.) MAGNESIUM. Symbol=Mg Atomic weight 24 (International^ :24.32) Mo- lecular weight 48 8p. gr=1.75. Occurs as carbonate in dolomite or magnesium 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 vegetable worlds. It is prepared by heating its chloride with Na, or by electrolysis of the fused chloride. It is a hard, light, malleable, ductile, white metal. It burns with great brilliancy when heated in air (magnesium light), but may be distilled in H. The flash light used by photog- raphers is a mixture of powdered Mg with an oxidizing agent, KC10 3 or KN0 3 . It decomposes vapor of H 2 when heated; reduces C0 2 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. Magnesium Oxide Calcined magnesia Magnesii oxidum Magnesia (U. S. P.) MgO 40 is obtained by calcining the car- bonates, hydroxide, or nitrate. It is a light, bulky, tasteless, odorless, amorphous, white powder ; alkaline in reaction ; almost insoluble in H 2 ; readily soluble without effervescence in acids. Magnesium Hydroxide Mg(OH) 2 58 occurs in nature, and is formed when a solution of a Mg salt is precipitated with excess of NaOH in absence of ammoniacal salts. It is a heavy, white powder, insoluble in H 2 0, absorbs C0 2 . Magnesium Chloride MgCL 95 is formed when MgO or MgC0 3 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. Like all the soluble Mg com- pounds it is bitter in taste, and accompanies the sulphate and bicar- bonate in the bitter waters. Magnesium Sulphate Epsom salt Seidlitz salt Magnesii sul- 174 TEXT-BOOK OF CHEMISTRY phas (U. S. P.) MgS0 4 +7Aq 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 H.,S0 4 on MgC0 3 : MgC0 3 +H 2 S0 4 =C0 2 +H 2 0+MgS0 4 It crystallizes in right rhombic prisms ; bitter, slightly effervescent, and quite soluble in H 2 0. Heated, it fuses and gradually loses 6Aq up to 132; the last Aq it loses at 210. Phosphates. Resemble those of Ca in their constitution and properties, and accompany them in the situations in which they occur in the animal body, but in much smaller quantity. Magnesium also forms double phosphates, constituted by the substitution of one atom of the bivalent metal for two of the atoms of basic hydrogen, of a molecule of phosphoric acid, and of an atom of alkaline metal, or of an ammonium group, for the remaining basic hydrogen. Ammonium-Magnesium Phosphate Triple phosphate Mg- (NH 4 )P0 4 +6Aq 137+108 is produced when an alkaline phos- phate and NH 4 OH are added to a solution containing Mg. When heated it is converted into magnesium pyrophosphate, Mg 2 P 2 7 , in which form H 3 P0 4 and Mg are usually weighed in quantitative analysis. Carbonates. Magnesium Carbonate Normal Magnesium car- bonate MgC0 3 84 exists native in magnesite, and, combined with CaC0 3 , in dolomite. It cannot be formed, like other carbonates, by decomposing a Mg salt with an alkaline carbonate, but may be ob- tained by passing C0 2 through H 2 holding tetramagnesic tricar- bonate in suspension. Tetramagnesic Tricarbonate Magnesia alba Magnesii carbo- nas (U. S. P.) 3MgC0 3 .Mg(OH) 2 +4Aq 310+72 occurs in com- merce in light, white cubes, composed of a powder which is amor- phous, or partly crystalline. It is prepared by precipitating a solu- tion of MgS0 4 with one of Na 2 C0 3 : 4MgS0 4 +4Na 2 C0 3 +5H 2 0=4Na 2 S0 4 +C0 2 +3MgC0 3 .Mg(OH) 2 4H 2 If the precipitation occurs in cold, dilute solutions, very little C0 2 is given off; a light, bulky precipitate falls (the light carbonate), and the solution contains magnesium, probably in the form of the bicarbonate Mg(HC0 3 ) 2 . This solution, on standing, deposits crys- tals of the carbonate, MgC0 3 +3Aq. If hot concentrated solutions ;nv used, and the liquid is then boiled upon the precipitate, C0 2 is given off, and a denser, heavier precipitate (the heavy carbonate) 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 is a mix- ture of magnesium carbonate and magnesium hydroxide. ZINC 175 Analytical Characters. (1) Ammonium hydroxide: voluminous, white ppt. from neutral solutions. (2) Potash or soda: voluminous white ppt. from warm solutions, prevented by the presence of NH 4 salts, and of certain organic substances. (3) Ammonium carbonate: slight ppt. from hot solutions; prevented by the presence of NH 4 salts. (4) Sodium or potassium carbonate : white ppt., best from hot solution; prevented by the presence of NH 4 compounds. (5) Disodic phosphate: white ppt. in hot, not too dilute solutions. (6) Oxalic acid : nothing alone, but in presence of NH 4 OH, a white ppt. ; not formed in presence of salts of NH 4 . ZINC. Sym'bol=Zii Atomic weight=65 (International = 65.37) Mo- lecular weight 65 Sp. #r.=6.862-7.215. Occurs principally in calamine (ZnC0 3 ) ; and Uende (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 malleable and ductile when pure. The commercial metal is usually brittle. At 130-150 it is pliable, and becomes brittle again above 200-210. At 500 it burns in air, with a greenish-white flame, and gives off snowy-white flakes of the oxide. In moist air it becomes coated with a film of zinc oxide and carbonate. It decomposes steam when heated. Pure H 2 S0 4 and pure Zn do not react together in the cold. If the acid is diluted, however, it dissolves the Zn, with evolution of H, and formation of ZnS0 4 , in the presence of a trace of Pt or Cu. The commercial metal dissolves readily in dilute H 2 S0 4 , with evolution of H, and formation of ZnS0 4 , 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 2 S0 4 if they form part of closed galvanic circuit; hence the zincs of galvanic batteries are protected by amalgamation. Zinc also decomposes HN0 3 , HC1, and acetic acid. Zinc dissolves in strong solutions of the caustic alkalies with evolution of hydrogen and formation of double oxides (zincates) : Zn+2KOH=Zn 2 K 2 +H 2 . It also decomposes many metallic salts in solution with deposition of the metal. 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 con- taminated metal. Zinc surfaces are readily attacked by weak organic acids. Vessels of galvanized iron or sheet zinc should therefore never be used to con- tain articles of food or medicines. 176 TEXT-BOOK OF CHEMISTRY Zinc Oxide Zinci oxidum (U. S. P.) ZnO 81 is prepared either by calcining the precipitated carbonate, or by burning Zn in a current of air. An impure oxide, known as tutty, is deposited in the flues of zinc furnaces, and in those in which brass is fused. When obtained by calcination of the carbonate, it forms a soft, white, tasteless, and odorless powder. When produced by burning the metal, it occurs in light, voluminous, white masses. It is neither fusible, volatile, nor decomposable by heat, and is completely in- soluble in neutral solvents. It dissolves in dilute acids, with forma- tion of the corresponding salts. It is used in the arts as a white pigment in place of lead car- bonate, and is not darkened by H 2 S. Zinc Hydroxide Zn( OH) 2 99 is not formed by union of ZnO and H 2 ; but is produced when a solution of a Zn salt is treated with KOH. Freshly prepared, it is very soluble in alkalies, and in solutions of NH 4 salts. Zinc Chloride Butter of zinc Zinci chloridum (U. S. P.) ZnCl 2 +Aq 136+18 is obtained by dissolving Zn in HC1, or by heating Zn in Cl. It is a soft, white, very deliquescent, fusible, vola- tile mass; very soluble in H 2 0, somewhat less so in alcohol. Its solution has a burning, metallic taste; destroys vegetable tissues;. dis- solves silk ; and exerts a strong dehydrating action upon organic sub- stances in general. In dilute solution it is used as a disinfectant and antiseptic (Bur- nett's fluid), as a preservative of wood and as an embalming injection. Liquor zinci chloridi (U. S. P.) is an aqueous solution of zinc chloride containing not less than 48.5 per cent, nor more than 52 per cent, of ZnCl 2 . Zinc Sulphate White vitriol Zinci sulphas (U. S. P.) ZnS0 4 +7Aq 161+126 is formed when Zn, ZnO, ZnS, or ZnC0 3 is dis- solved in diluted H 2 S0 4 : Zn+H 2 S0 4 +zH 2 0=:rH 2 0+H 2 +ZnS0 4 It crystallizes below 30 with 7 Aq; at 30 with 6 Aq; between 40 -50 with 5 Aq ; at from concentrated acid solution with 4 Aq. From a boiling solution it is precipitated by concentrated H 2 S0 4 with 2 Aq; from a saturated solution at 100 with 1 Aq; and anhydrous, when the salt with 1 Aq is heated to 238. The salt usually met with is that with 7 Aq, which is in large, colorless, four-sided prisms; efflorescent; very soluble in H 2 0, spar- ingly soluble in weak alcohol. Its solutions have a strong, styptic taste : coagulate albumen when added in moderate quantity, the coag- ulum dissolving in an excess; and form insoluble precipitates with the tannins. Carbonates. Zinc Carbonate ZnC0 3 125 occurs in nature as calamine. If an alkaline carbonate is added to a solution of a Zn CADMIUM 177 salt, the neutral carbonate, as in the case of Mg, is not formed, but an oxycarbonate, ttZnC0 3 , ?iZn(OH) 2 , whose composition varies with the conditions under which it is formed. Analytical Characters. (1) K, Na or NH 4 hydroxide: white ppt., soluble in excess. (2) Carbonate of K or Na: white ppt., in absence of NH 4 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, unless sodium acetate is also present. (4) Ammonium sulphydrate: white ppt., insoluble in excess, in KOH, NH 4 OH, or acetic acid; soluble in dilute mineral acids. (5) Ammonium car- bonate: white ppt., soluble in excess. (6) Disodic phosphate, in absence of NH 4 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 behave as true poisons; and solutions of the chloride (in common use by tinsmiths, and in disinfecting fluids) has also well-marked cor- rosive 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, such as 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 become con- taminated 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. Sym~bol=:Cd Atomic weight=1.12 (International :112.40) Mo- lecular weigJitl\28p. #r.=8.604. A white metal, malleable and ductile at low temperature, brittle when heated ; which accompanies Zn in certain of its ores. It resem- bles 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.; insoluble in NH 4 HS, and in dilute acids and alkalies, soluble in boil- ing HN0 3 or HC1. V. ALUMINIUM GROUP. GLUCINUM ALUMINIUM SCANDIUM GALLIUM INDIUM. The existence of the aluminates, such as K 2 A1 2 4 , would seem to place aluminium in the amphoteric class. These compounds, which are formed by the reactions: A1(OH) 3 +KOH=KA1(X+2H 2 0, and Al 2 -f2KOH-f-2H 2 0=2KA10 2 +3H 2 , are double oxides rather than salts. They resemble the zincates and what has been said concerning those compounds (see p. 175) applies also to the aluminates. 178 TEXT-BOOK OF CHEMISTRY ALUMINIUM. Symbol^Al Atomic weight=21 (International=27.1) Molecu- lar weight 54^- Sp. gr. 2.56-2.61. Occurrence. Never found in the free state, but abundant in the clays as silicate. Also in feldspar, mica, and garnet, topaz, and emerald. As a fluoride in cryolite, and as a hydroxide in bauxite. Preparation. (1) By decomposing vapor of aluminium chloride by Na or K (Wohler). (2) Aluminium hydroxide, mixed with sodium chloride and charcoal, is heated in Cl, by which a double chloride of Na and Al (NaAlClJ is formed. This is then heated with Na, when Al and NaCl are produced. (3) These ''chemical methods" have been replaced, in the industrial preparation of aluminium, by the electrolytic method, in which a mixture of cryolite and bauxite is treated in an electric furnace. Properties. Physical. A bluish-white metal; hard; quite mal- leable, and ductile, when annealed from time to time; slightly mag- netic; a good conductor of electricity; non- volatile ; very light, and exceedingly sonorous. Chemical. It is not affected by air or 0, except at very high tem- peratures, and then only superficially. If, however, it contains Si, it burns readily in air, forming aluminium silicate. It does not decom- pose H 2 at a red heat ; but in contact with Cu, Pt, or I, it does so at 100. It combines directly with B, Si, Cl, Br, and I. It is attacked by HC1, gaseous or in solution, with evolution of H, and formation of A1C1 3 . It dissolves in alkaline solutions, with forma- tion of aluminates, and liberation of H. It alloys with Cu to form a golden yellow metal (aluminium bronze). Aluminium Oxide Alumina A1 2 3 102 occurs in nature, nearly pure, as corundum, emery, ruby, sapphire, and topaz; and is formed artificially, by calcining the hydrate, or ammonium alum, at a red heat: 2 Al ( OH ) 3 3H 2 0+ A1 2 3 Al, (S0 4 ) 3 . (NH 4 ) 2 S0 4 = (NH 4 ) 2 S0 4 +3S0 3 + A1 2 3 It is a light, white, odorless, tasteless powder; fuses with diffi- culty; and, on cooling, solidifies in very hard crystals. Unless it has been heated to bright redness, it combines with H 2 0, with eleva- tion of temperature. It is almost insoluble in acids and alkalies. H 2 S0 4 , diluted with an equal bulk of H 2 0, dissolves it slowly as (A1 2 )(S0 4 ) 3 . Fused potash and soda combine with it to form alu- minates. It is not reduced by charcoal. Aluminium Hydroxide Aluminium hydrate Alumini hydroxi- dum (U. S. P.) A1(OH) 3 78 is formed when a solution of alu- ALUMINIUM 179 minium" salt is decomposed by an alkali, or alkaline carbonate. It constitutes a gelatinous mass, which, when dried, leaves an amorphous, translucid mass; and, when pulverized, a white, tasteless, amorphous powder. When the liquid in which it is formed contains coloring matters, these are carried down with it, and the dried deposits are used as pigments, called lakes. It is used as a mordant. When freshly precipitated, it is insoluble in H 2 ; soluble in acids, and in solutions of the fixed alkalies. When dried at a tem- perature above 50, or after 24 hours' contact with the mother liquor, its solubility is greatly diminished. With acids it forms salts of aluminium; and with alkalies, aluminates of the alkaline metal. Heated to near redness, it is decomposed into A1 2 3 , and H 2 0. A soluble modification is obtained by dialyzing a solution of A1(OH) 3 in A1C1 3 , or by heating a dilute solution of aluminium acetate for 24 hours. Aluminium Chloride A1C1 3 133.5 is prepared by passing Cl over a mixture of A1 2 3 and C, heated to redness, or by heating clay in a mixture of gaseous HC1 and vapor of CS 2 . It crystallizes in colorless, hexagonal prisms; fusible; volatile; deliquescent; very soluble in H 2 and in alcohol. From a hot, con- centrated solution, it separates in prisms with 12Aq. The disinfectant called chloralum is a solution of impure A1C1 3 . Aluminium Sulphate Al 2 (SOJ 3 +18Aq 342+324 is obtained by dissolving A1(OH) 3 , in H 2 S0 4 or (industrially) by heating clay with H 2 S0 4 . It crystallizes, with difficulty, in thin, flexible plates; soluble in H 2 ; very sparingly soluble in alcohol. Heated, it fuses in its Aq, which it gradually loses up to 200, when a white, amorphous pow- der, A1 2 (S0 4 ) 3 , remains: this is decomposed at a red heat, leaving a residue of pure alumina. Alums are double sulphates of an univalent, alkaline, metal, and trivalent metal (Fe, Mn, Cr, or Al). When crystallized, they have the general formula: M i M iii (S0 4 ) 2 +12Aq. They are isomor- phous with each other. Alum Alumen (U. S. P.) The official alum is the ammonium alum (ammonium aluminium sulphate) NH 4 .Al(S0 4 ) 2 +12Aq 237+ 216, or the potassium alum (potassium aluminium sulphate) K.A1- (SOJ 2 +12Aq 258+216. It is formed when solutions of the sulphates are mixed in suitable proportions. It crystallizes in large, transparent, regular octa- hedra; has a sweetish, astringent taste, -and is readily soluble in H 2 0. Dried alum, burnt alum=alumen exsiccatum (U. S. P.) is an- hydrous A1.NH 4 .(S0 4 ) 2 or A1.K(S0 4 ) 2 ; and is alum from which the water of crystallization has been driven out by heat. It is a white powder, readily soluble in boiling water, but slowly soluble in cold 180 TEXT-BOOK OF CHEMISTRY water. Alum is used in dyeing, and in purification of water by precipitation. Silicates are very abundant in the different varieties of clay, feldspar, albite, labradorite, mica, etc. The clays are hydrated aluminium silicates, more or less contaminated with alkaline and oarthy salts and iron, to which last certain clays owe their color. The purest is kaolin, or porcelain clay, a white or grayish powder. They are largely used in the manufacture of the different varieties of bricks, terra cotta, pottery, and porcelain. Porcelain is made from the purer clays, mixed with sand and feldspar; the former to prevent shrinkage, the latter to bring the mixture into partial fusion, and to render the product translucent. The fashioned articles are subjected to a first baking. The porous, baked clay is then coated with a glaze, usually composed of oxide of lead, sand, and salt. During a second baking the glaze fuses, and coats the article with a hard, impermeable layer. The coarser articles of pottery are glazed by throwing sodium chloride into the fire; the salt is volatilized, and on contact with the hot aluminium silicate, deposits a coating of the fusible sodium silicate, which hardens on cooling. Analytical Characters. (1) Potash, or soda: white ppt., soluble in excess. (2) Ammonium hydroxide: white ppt., almost insoluble in excess, especially in presence of ammoniacal salts. (3') Sodium phos- phate: white ppt., readily soluble in KOH and NaOH, but not in NH 4 OH; soluble in mineral acids, but not in acetic acid. (4) Blow- pipe on charcoal does not fuse, and moistened with cobalt nitrate solution turns dark sky-blue. VI. NICKEL GROUP. NICKEL COBALT. These two elements bear some resemblance chemically to those of the Fe group; from which they differ in forming, so far as known, no compounds similar to the ferrates, chromates, and manganates. They are often associated with iron, and, like iron, are attracted by the magnet. NICKEL. =Ni Atomic weight = 58 (International 58.68) Sp. 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. Nickel is now exten- sively used for plating upon other metals, and for the manufacture of dishes, etc., for use in the laboratory. Its salts are green. Nickelous Sulphate NiS0 4 is obtained by dissolving the metal, hydroxide or carbonate in ILSO 4 . It forms green crystals with 7 Aq, COBALT COPPER 181 and combines with (NH 4 ) 2 S0 4 to form a double sulphate, used in the nickel-plating bath, for which use it must be free from K or Na. Analytical Characters. (1) Ammonium sulphydrate: black ppt. ; insoluble in excess. (2) Potash or soda: apple-green ppt., in ab- sence of tartaric acid; insoluble in excess. (3) Ammonium hydrate: apple-green ppt. ; soluble in excess ; forming a violet solution, which deposits the apple-green hydrate, when heated with KOH. COBALT. Symbol Co Atomic weight = 59 (International = 58.97) Sp. 0r.=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 pigment. 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 the presence of NH 4 salts. ( 3 ) Ammonium hydroxide : blue ppt. ; turns red in ab- sence of air, green in its presence. VII. COPPER GROUP. COPPER MERCURY. Each of these elements forms two series of compounds. One is univalent, Cu' or Hg', and is distinguished by the termination ous ; the other is bivalent, Cu" or Hg", and is designated by the termina- tion ic. Some writers double the formula? of the ous salts, but the more modern practice is to write HgCl and not Hg 2 Cl 2 , etc. COPPER. Symbol=Cu (Cuprum) Atomic weight^ (International = 63.57) Molecular weight 127 Sp. #r.=8.914-8.952. Occurrence. It is found free, in crystals or amorphous masses, sometimes of great size ; also as sulphide, copper pyrites; oxide, ruby ore and black oxide; and basic carbonate, malachite, a mixed car- bonate and hydroxide of copper, CuC0 3 .Cu(OH) 2 . Properties. Physical. A yellowish-red metal; dark-brown when finely divided; very malleable, ductile, and tenacious; a good con- ductor 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 182 TEXT-BOOK OF CHEMISTRY 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.,S0 4 dissolves it with formation of CuS0 4 and SO.,. It is dissolved by HN0 3 with formation of Cu(NO,) L> and NO; and by IIC1 with libera- tion of H. Weak acids form with it soluble salts, in presence of air and moisture. It is dissolved by NH 4 OH, in presence of air, with formation of a blue solution. It combines directly with Cl, fre- quently with light. Oxides. Cuprous Oxide red oxide of copper Cu 2 143 is formed by calcining a mixture of CuCl and Na 2 C0 3 ; or a mixture of CuO and Cu. It is a red or yellow powder; permanent in air; sp. gr. 5.749-6.093 ; fuses at a red heat ; easily reduced by C or H. Heated in air it is converted into CuO. Cupric Oxide Black oxide of copper CuO 79 is prepared by heating Cu to dull redness in air; or by calcining Cu(N0 3 ) 2 ; or by prolonged boiling of the liquid over a precipitate, produced by heat- ing a solution of a cupric salt, in presence of glucose, with KOH. By the last method it is sometimes produced in Trommer's test for glucose, when an excessive quantity of CuS0 4 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 0, converting the C into C0 2 , and the H into H 2 : C 2 H 6 0+6CuO=6Cu+2C0 2 +3H 2 a property which renders it valuable in organic analysis, as by heat- ing a known weight of organic substances with CuO, and weighing the amount of C0 2 and H 2 produced, the percentage of C and H may be obtained. It dissolves in acids with formation of salts. Hydroxides Cuprous Hydroxide CuOH 80 is formed as a yellow or red powder when mixed solutions of CuS0 4 and KOH are heated in presence of glucose. By boiling the solution it is rapidly dehydrated with formation of Cu 2 0. Cupric Hydroxide Cu(OH) 2 97 is formed by the action of KOH upon solution of CuS0 4 , in absence of reducing agents and in the cold. It is a bluish, amorphous powder; very unstable, and readily dehydrated, with formation of CuO. Chlorides. Cuprous Chloride CuCl 98.5 is prepared by heating Cu with one of the chlorides of Hg; by dissolving Cu 2 in HC1. without contact of air; or by the action of reducing agents on solutions of CuCl 2 . It is a heavy, white powder; turns violet and blue by exposure to light: soluble in HC1; insoluble in H 2 O. It forms a crystallizable compound with CO; and its solution in HC1 is used in analysis to absorb that gas. Cupric Chloride CuCl 2 134 is formed by dissolving Cu in aqua regia. If the Cu is in excess, it reduces CuCl 2 to CuCl. It eryst all i/.es in bluish-green, rhombic prisms with 2 Aq; deliquescent ; very soluble in H,O and in alcohol. Cupric Nitrate C u (No, I. 187 is formed by dissolving Cu, CuO. or COPPER 183 CuC0 3 in HN0 3 . It crystallizes' at 20-25 with 3 Aq; below 20 with 6 Aq, forming .blue, deliquescent needles. Strongly heated, it is converted into CuO. Cupric Sulphate Blue vitriol Bluestone Cupri sulphas (U. S. P.) CuS0 4 -f-5Aq 159+90 is prepared: (1) by roasting CuS; (2) from the water of copper mines; (3) by exposing Cu, moistened with dilute H 2 S0 4 , to air; (4) by heating Cu with H 2 S0 4 . As ordinarily crystallized, it is in fine, blue, oblique prisms ; solu- ble in H 2 ; insoluble in alcohol ; efflorescent in dry air at 15 , losing 2 Aq. At 100 it still retains 1 Aq, which it loses at 230, leaving a white, amorphous powder of the anhydrous salt, which, on taking up H 2 0, resumes its blue color. Its solutions are blue, acid, styptic, and metallic in taste. When NH 4 OH is added to a solution of CuS0 4 , a bluish-white precipitate 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 CuS0 4 ,4NH 3 -f-H 2 0, which are very soluble in H 2 O. This solution constitutes ammonio-sulphate of copper or aqua sapphirina. Cupric Arsenite Scheele's green Mineral green is a mixture of cupric arsenite, HCuAs0 3 , and hydroxide; prepared by adding potassium arsenite to solution of CuSO 4 . It is a grass-green powder, insoluble in H 2 0; soluble in NH 4 OH, or in acids. Exceedingly poisonous. Schweinfurt Green Mitis green or Paris green is the most frequently used, and the most dangerous of the cupro-arsenical pigments. It is prepared by adding a thin paste of neutral cupric acetate with H 2 to a boiling solution of arsenous acid, and continuing the boiling during a further addition of acetic acid. It is an insoluble, green, crystalline powder, having the composition (C 2 H 3 2 ) 2 Cu-f3Cu(As0 2 ) 2 , and is therefore cupric aceto-metarsenite. It is de- composed by prolonged boiling in H 2 0, by aqueous solutions of the alkalies, and by the mineral acids. Acetates. Cupric Acetate Cu ( C 2 H 3 O 2 ) 2 -|-Aq 181-J-18 is formed when CuO or verdigris is dissolved in acetic acid; or by decomposition of a solution of CuS0 4 by Pb(C 2 H 3 O 2 ),. It crystallizes in large, bluish-green prisms, which lose their Aq at 140. At 240-260 they are decomposed with 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 bluish-green coating from the copper. It is a mixture, in varying proportions, of three different substances: ( C 2 H 3 2 ) 2 Cu ( OH ) -f-5Aq ; [(C 2 H 3 2 ) 2 Cu] 2 , Cu(OH) 2 -f5Aq; and ( C 2 H 3 2 ) 2 Cu,2 ( CuH 2 2 ) . Analytical Characters. CUPROUS are very unstable and readily converted into cupric compounds. (1) Potash: white ppt. ; turning brownish. (2) Ammonium hydroxide, in absence of air: a colorless liquid ; turns blue in air. CUPRIC are white when anhydrous; when soluble in H 2 they form blue or green, acid solutions. (1) Hydrogen sulphide: black ppt. ; insoluble in KHS or NaHS ; sparingly soluble in NH 4 HS ; solu- ble in hot concentrated HN0 3 and in KCN. (2) Alkaline sulphy- drates: same as H 2 S. (3) Potash, or soda: pale blue ppt.; insoluble 184 TEXT-BOOK OF CHEMISTRY in excess. If the solution be heated over the ppt., the latter contracts and turns black. (4) Ammonium hydroxide, in small quantity: pale blue ppt. ; in larger quantity: deep blue solution. (5) Potassium or sodium carbonate: greenish-blue ppt.; insoluble in excess; turn- ing 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 fer- rocyanide : chestnut-brown ppt. ; insoluble in weak acids ; decolorized by KOH. (9) Iron is coated with metallic Cu. Action on the Economy. Certain of the copper compounds, such as the sulphate, having a tendency to combine with protein and other animal sub- stances, produce symptoms of irritation by their direct local action, when brought in contact with the gastric or intestinal mucous membrane. A char- acteristic symptom of such irritation is the vomiting of a greenish matter, which develops a blue color upon the addition of NH 4 OH. Severe illness, and even death, has followed the use of food which lias been in contact with imperfectly tinned copper vessels. It is probable that the poisonous action attributed to copper is sometimes 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 im- probable 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 proteins an inert compound is formed by the copper salt. If vomiting does not occur spon- taneously, it should be induced by the usual methods. The detection of copper in the viscera after death is not without interest, especially if arsenic has been found, in which case its discovery or non-discovery enables us to differentiate between poisoning by the arsenical greens, and that by other arsenical compounds. The detection of mere traces of copper is of no significance, because, although copper is not a physiological constituent of the body, it is almost invariably present, 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 is present the steel will be found to be coated with copper after half an hour's contact. MERCURY. Symbol=Hg (Hydrargyrum) Atomic weigJit2QQ (Interna- tional 200.6) Molecular weight=200Sp. gr. of liquid^ 13.596 ; of vapor=6.91. Occurrence. Chiefly as cinnabar (HgS) ; also in small quantity free and as chloride. Preparation. The commercial product is usually obtained by MERCURY 185 simple distillation in a current of air: HgS+0 2 =Hg-f-S0 2 . If re- quired-pure, it must be freed from other metals by distillation, and agitation of the redistilled product with mercurous nitrate solution, solution of FeCl 3 , or dilute HN0 3 . Properties. Physical. A bright metallic liquid, commonly known as quicksilver; volatile at all temperatures. Crystallizes in octahedra of sp. gr. 14.0. When pure, it rolls over a smooth surface in round drops. The formation of tear-shaped drops indicates the presence of impurities. Chemical. If pure, it is not altered by air at the ordinary tem- perature, but, if contaminated with foreign metals, its surface be- comes dimmed. Heated in air, it is oxidized superficially to HgO. It does not decompose H 2 0. It combines directly with Cl, Br, I, and S. It alloys readily with most metals to form amalgams. It amalga- mates with Fe and Pt with difficulty. Hot, concentrated, H 2 S0 4 dissolves it, with evolution of S0 2 , and formation of HgS0 4 . It dis- solves in cold HN0 3 , with formation of a nitrate. An alloy is a substance composed of two or more metals. An amalgam is an alloy containing mercury. Elementary mercury is insoluble in H 2 0, and probably in the digestive liquids. It enters, however, into the formation of three medicinal agents: hydrargyrum cum creta (U. S. P.), containing 38 per cent, of Hg; massa hydrargyri (U. S. P.), containing 33 per cent, of Hg; and unguentum hydrargyri (U. S. P.), 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 2 . Oxides. Mercurous Oxide Black oxide of mercury Hg 2 416 is obtained by adding a solution of HgN0 3 to an excess of solution of KOH. It is a brownish black, tasteless powder; very prone to decomposition into HgO and Hg. It is converted into HgCl by HC1; and by other acids into the corresponding mercurous salts. It exists in black wash, obtained by mixing together calomel and lime water: 2HgCl+Ca(OH) 2 =H 2 0+CaCl 2 +Hg 2 Mercuric Oxide Yelloiv oxide of mercury Red oxide of mercury Hydrargyri oxidum flavum (U. S. P.) Hydrargyri oxidum rubrum (U. S. P.) HgO 216 is prepared by two methods: (1) by calcining Hg(N0 3 ) 2 , as long as brown fumes are given off (Hydr. oxid. rubr.} : 2Hg(N0 3 ) 2 =4N0 2 +0 2 +2HgO 186 TEXT-BOOK OF CHEMISTRY or, (2) by precipitating a solution of a mercuric salt by excess of KOH (Hydr. oxid. flavum] : HgCl 2 +2KOH=2KCl+H 2 0-fHgO 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 2 0, the solution having an alka- line reaction, and a metallic taste. It exists both in solution and in suspension in yellow wash, prepared by the action of Ca(OH) 2 on mercuric chloride: HgCl 2 +Ca(OH) 2 =H 2 0+CaCl 2 +HgO. Exposed to light and air, it turns black, more rapidly in presence of organic matter, giving off 0, and liberating Hg:HgO=Hg-(-0. It decomposes the chlorides of many metallic elements in solution, with formation of a metallic oxide and mercuric oxychloride. Chlorides. Mercurous Chloride Protocliloride or mild chloride of mercury Calomel Hydrargyri chloridum mite (U. S. P.) HgCl 235.5 is obtained by heating a mixture of mercuric sulphate, mercury, and sodium chloride, when the calomel (which volatilizes) is condensed: Hg+HgS0 4 +2NaCl=Nji 2 S0 4 +2HgCl Calomel is also formed in a number of other reactions: (1) By the action of Cl upon excess of Hg. (2) By the action of Hg upon FeCl 3 . (3) By the action of HC1, or of a chloride, upon Hg,0, or upon a mercurous salt. (2) By the action of reducing agents, in- cluding Hg, upon HgCl 2 . Calomel crystallizes in nature, and, when sublimed, in quadratic prisms. When precipitated it is deposited as a heavy, amorphous, white powder, faintly yellowish, and producing a yellowish innrk when rubbed upon a dark surface. It sublimes, without fusing, be- tween 420 and 500, is insoluble in cold H 2 and in alcohol; soluble in boiling H 2 O to the extent of 1 part in 12,000. When boiled with H 2 for some time, it suffers partial decomposition, Hg is deposited and HgCl 2 dissolves. Although HgCl is insoluble in H 2 0, in dilute HC1 and in pepsin solution, it is dissolved at the body temperature in an aqueous solu- tion 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,: 2HgCl=Hg+HgCl.,. It is converted into HgCL by Cl or aqua regia: 2HgCl+Cl 2 =2Hpr<'l.,. In the presence of I !..<)', I con- verts it into a mixture of Hgci.. and HgI 2 : 2HgCl+I 2 =H>?Cl 2 + MERCURY 187 HgI 2 . It Is also converted into HgCl 2 by HC1 and by alkaline chlor- ides: 2JIgCl=HgCl 2 -f Hg. This change occurs in the stomach when calomel is taken internally, and that to such an extent when large quantities of NaCl are 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 Hgl : HgCl-f-KI =KCl-f-HgI ; which is then decomposed by excess of KI into Hg and HgI 2 , the latter dissolving: 2HgI=Hg-|-HgI 2 . Solutions of the sulphates of Na, K and NH 4 dissolve notable quantities of HgCl. The hydroxides and carbonates of K and Na decompose it with formation of H 2 0: 2HgCl+Na 2 C0 3 =Hg 2 04-C0 2 +2NaCl; and the Hg 2 so formed is decomposed into HgO and Hg. If alkaline chlorides are present, they react upon the HgO so produced with formation of HgCl 2 . Mercuric Chloride Perchloride or bichloride of mercury Cor- rosive sublimate Hydrargyri chloridum corrosivum (U. S. P) ; HgCl 2 271 is prepared by heating a mixture of 5 pts. dry HgS0 4 with 5 pts. dry NaCl, and 1 pt. Mn0 2 in a glass vessel communicating with a condensing chamber. It crystallizes by sublimation in octahedra, and by evaporation of its solutions in flattened, right rhombic prisms; fuses at 265, and boils at about 295 ; soluble in H 2 and in alcohol ; very soluble in hot HC1, the solution gelatinizing on cooling. Its solutions have a disagreeable, acid, styptic taste, and are highly poisonous. Although HgCL is heavier than water (sp. gr.=5.4) when the crystalline powder is thrown upon water a portion floats for some time. It is easily reduced to HgCl 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 HgCl. When dry HgCl 2 , or its solution, is heated with Zn, Cd, Ni, Fe, Pb, Cu, or Bi, those elements remove part or all of its Cl, with separation of HgCl or Hg. Its solution is decomposed by H 2 S, with separation of a yellow sulphochloride, which, with an ex- cess of the gas, is converted into black HgS. It is soluble without de- composition in H 2 S0 4 , HN0 3 , and HC1. It is decomposed by KOH or NaOH, with separation of a brown oxychloride if the alkaline hydroxide is in limited quantity; or of the orange-colored HgO if it is in excess. A similar decomposition is effected by Ca(OH), and Mg(OH) 2 ; 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 HgCl or Hg, especially under the influence of sunlight. Thus in sunlight it is reduced by oxalic acid, which is itself oxidized to carbon dioxide : 2HgCU+a0 4 H,=2HgCl-h2C0 2 +2HCl. For this reason it behaves as an"oxidant:~2HgCl 2 +H 2 0=2HgCl+2HCl-fO. Albumin forms with it a white precipitate, which is insoluble in H 2 0, but soluble in 188 TEXT-BOOK OF CHEMISTRY an excess of fluid albumin and in solutions of alkaline chlorides. It is a very energetic germicide. Mercurammonium Chloride White precipitate Ammoniated mercury Hydrargyrum ammoniatum (U. S. P.) NH 2 HgCl 251.5 is prepared by adding a slight excess of NH 4 OH to a solution of HgCl 2 . It contains 79 per cent, of Hg; and is a white powder, insoluble in alcohol, ether, and cold H 2 : decomposed by hot H 2 0, with separation of a heavy, yellow powder. It is entirely volatile, without fusion. The fusible white precipitate is formed in small crystals when a solution containing equal parts of HgCl 2 and NH 4 C1 is decomposed by Na 2 C0 3 . It is mercurdiammonium chloride, NH 2 Hg,NH 4 Cl 2 . Iodides. Mercurous Iodide Protoiodide or yellow iodide Hydrargyri iodidum flavum (U. S. P.) Hgl 327 is prepared by grinding together 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 H 2 and in alcohol. When heated, it turns brown, and volatilizes completely. When exposed to light, or even after a time in the dark, it is decomposed into HgI 2 and Hg. The same decomposition is brought about instantly by KI ; more slowly by solutions of alkaline chlorides, and by HC1 when heated. NH 4 OH dissolves it with separation of a gray precipitate. Mercuric Iodide Biniodide or red iodide Hydrargyri iodidum rubrum (U. S. P.) HgI 2 454 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 iodhydrargyrate may not be formed : HgCl 2 +2KI=2KCl+HgI 2 It is sparingly soluble in H 2 ; but forms colorless solutions with alcohol. It dissolves readily in many dilute acids, and in solutions of ammoniacal salts, alkaline chlorides, and mercuric salts; and in solu- tions of alkaline iodides. Iron and copper convert it into Hgl, then into Hg. The hydroxides of K and Na decompose it into oxide or oxyiodides, .and combine with another portion to form iodhydrargy- rates, which dissolve. NH 4 OH separates from its solution a brown powder, and forms a yellow solution, which deposits white flocks. Mercuric Cyanide Hg(CN) 2 252 is best prepared by heat- ing together, for a quarter of an hour, potassium ferrocyanide, 1 pt. ; HgS0 4 , 2 pts. ; and H 2 0, 8 pts. It crystallizes in quadrangular prisms ; soluble in 8 pts. of H 2 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 2 it yields HCN, Hg, C0 2 , and NH 3 . Hot concentrated H 2 S0 4 , and HC1, HBr, HI, and H 2 S in the cold decompose it, with liberation of HCN. It is not decomposed by alkalies. MERCURY 189 Nitrates Mercurous Nitrate HgN0 3 + 2 Aq 262 +36 is formed when excess of Hg is digested with moderately diluted HNO 3 : 3Hg+4HN0 3 =:3HgN0 3 +NO+2H 2 It effloresces in air ; fuses at 70 ; dissolves in a small quantity of hot H 2 0, but with a larger quantity is decomposed with separation of the yellow, basic trimercuric nitrate, Hg(N0 3 ) 2 ,2HgO-f-Aq. Mercuric Nitrate Hg(N0 3 ) 2 324 is formed when Hg or HgO is dissolved in excess of HN0 3 , and the solution evaporated at a gentle heat: 3Hg+8HN0 3 =3Hg(NO s ) 2 +2NO+4H 2 O This salt is soluble in H 2 0, and exists in the volumetric standard solution used in Liebig's process for urea; and probably in citrine ointment='Unguentum hydrarargyri nitratis (U. S. P.). Sulphates. Mercurous Sulphate Hg 2 S0 4 496 is a white, crystalline powder, formed by gently heating together 2 pts. Hg and 3 pts. H 2 S0 4 , and causing the product to combine with 2 pts. Hg. Heated with NaCl it forms HgCl. Mercuric Sulphate HgS0 4 296 is obtained by heating to- gether Hg and H 2 S0 4 , or Hg, H 2 S0 4 , and HN0 3 . It is a white, crystalline, anhydrous powder, which, on contact with H 2 0, is de- composed with formation of trimercuric sulphate, HgS0 4 , 2HgO; a yellow, insoluble powder, known as turpeth mineral. Analytical Characters. MERCUROUS. (1) Hydrochloric acid: white ppt. ; insoluble in H 2 and in acids ; turns black with NH 4 OH ; when boiled with HC1, deposits Hg, while HgCL dissolves. (2) Hy- drogen sulphide ; black ppt. ; insoluble in alkaline sulphydrates, in dilute acids, and in KCN; partly soluble in boiling HN0 3 . (3) Potash: black ppt.; insoluble in excess. (4) Potassium iodide: green- ish ppt. ; converted by excess into Hg, which is deposited and HgI 2 , which dissolves. MERCURIC. (1) Hydrogen sulphide: black ppt. If the reagent is slowly added, the ppt. is first white, then orange, finally black. (2) Ammonium sulphydrate : black ppt. ; insoluble in excess, except in the presence of organic matter. (3) Potash, or soda: yellow ppt.; insoluble in excess. (4) Ammonium hydroxide: white ppt.; soluble in great excess and in solutions of NH 4 salts. (5) Potassium car- bonate: 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 quan- tity: white ppt.; in larger quantity: gray ppt.; and when boiled: deposit of globules of Hg. Action on the Economy. Metallic mercury is without action upon the animal economy. On contact, however, with alkaline chlorides it is converted into a soluble double chloride, and this the more readily the greater the degree 190 TEXT-BOOK OF CHEMISTRY 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 protein bodies, 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 absorption, it is a more dangerous poison than As 3 O 3 . In poisoning by HgCl 2 , the symptoms begin sooner after the ingestion of the poison than in arsenical poisoning, and those phenomena referable to the local action of the toxic are more intense. But the entire duration of the poisoning is greater. In fatal cases, death usually occurs in 5 to 12 days. 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 protein bodies, from which it may be set free, or, more properly, brought into soluble combination, at a period quite removed from the date of last administration, 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. ORGANIC CHEMISTRY COMPOUNDS OF CARBON. In the beginning of the nineteenth century chemistry was divided into the two sections of inorganic and organic. The former treated of the products of the mineral world, the latter of substances pro- duced in organized bodies, vegetable or animal. This subdivision, originally made upon the supposition that organic substances could only be produced by "vital processes," is retained only for con- venience and because of the great number of the carbon compounds. When it was found that organic substances were made up of a very few elements, and that they all contained carbon, Gmelin pro- posed to consider as organic substances all such as contained more than one atom of C, his object in thus limiting the minimum number of C atoms being that substances containing one atom of C, such as carbon dioxide and marsh gas, are formed in the mineral kingdom, and consequently, according to then existing views, could not be con- sidered as organic. Such a distinction, still adhered to in some text- books, of necessity leads to most incongruous results. Under it the first terms of the homologous series (see p. 193) of saturated hydro- carbons, CH 4 , alcohol, CH 4 O, acids, CH 2 2 , and all their derivatives are classed among mineral substances, while all the higher terms of the same series are organic. Under it urea, CON 2 H 4 , the chief prod- uct of excretion of the animal body, is a mineral substance, but ethene, C 2 H 4 , obtained from the distillation of coal, is organic. The idea of organic chemistry conveyed by the definition : " that branch of the science of chemistry which treats of the carbon com- pounds containing hydrogen," is still more fantastic. Under it hy- drocyanic acid, CNH, is organic, but the cyanides, CNK, are min- eral. Oxalic acid, C 2 4 H 2 , is organic, and potassium hydroxide, KOH, unquestionably mineral. If these two act upon each other in the proportion of 90 parts of the former to 56 of the latter, the organic monopotassic oxalate, C 2 4 HK, is formed, but if the pro- portion of KOH is doubled, other conditions remaining the same, the mineral dipotassic oxalate, C 2 4 K 2 , is produced. Similarly one of the sodium carbonates, Na 2 C0 8 , is mineral; the other, NaHC0 3 , is organic. The notion that organic substances could only be formed by some mysterious agency, manifested only in organized beings, was finally exploded by the labors of Wohler and Kolbe. The former obtained urea from ammonium cyanate (1828) ; while the latter, at a subse- quent period, formed acetic acid, using in its preparation only such 191 192 TEXT-BOOK OF CHEMISTRY unmistakably mineral substances as coal, sulphur, aqua regia, and water. Since Wohler's first synthesis, chemists have succeeded not only in making from mineral materials many of the substances pre- viously only formed in the laboratory of nature, but have also pro- duced a vast number of carbon compounds which were previously unknown, and which, so far as we know, have no existence in nature. At the present time, therefore, we must consider as an organic substance any compound containing carbon, whatever may be its origin and whatever its properties. Organic chemistry is, therefore, simply the chemistry of the car- bon compounds. In the study of the compounds of the other ele- ments, 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. Al- though compounds have been formed which contain C along with each of the other elements, the great majority of the organic sub- stances are made up of C, combined with a very few other elements ; H, 0, 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. 45). 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 interchanging valences. Were it not for this property of the C atoms, we could have but one saturated compound of carbon and hydrogen, CH 4 , or expressed graphically: A 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 H H H H H H H H H C C H H C C C C H COMPOUNDS OF CARBON 193 Homologous Series. It will be observed that these formulas differ jrom each other by CH 2 or some multiple of CH 2 , 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 2 ; such a series is called an homologous series. It will be readily understood that such an arrangement in series vastly facilitates the remembering of the composition of organic bodies. In the following table, for example, are given the saturated hydro- carbons, 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 SERIES. Saturated hy- drocarbons, CH2n+2 Alcohols, CnIl2n+2O Aldehydes CnH2nO Acids, CnH2nO2 Ketones CnH2O CH 4 CH 4 CH,0 C0 2 H 2 C 2 H 6 C 2 H 6 C 2 H 4 C 2 2 H 4 . C 3 H 8 C 3 H 8 C 3 H 6 C 3 2 H 6 C 3 H0 C 4 H 10 C 4 H 10 C 4 H 8 C 4 2 H 8 C 4 H 8 C 5 H 12 C 5 H 12 C 5 H 10 C 5 2 H 10 C 8 H 10 C 6 H 14 C 6 H 12 C 6 2 H 12 CE C 7 H 16 C 7 H 14 C 7 2 H 14 , C S H 18 C 8 H 18 C 8 H 16 C 8 2 H 18 . C 9 H 20 C 9 H 20 C 9 2 H 18 , C 10 H 22 C 10 H 22 O C 10 2 H 20 CaH* '. '. '. '. C 12 O 2 H 24 ; C 13 H 28 . . C 14 H 30 .... C 14 2 H 28 But the arrangement in homologous series does more for us than this. The properties of substances in the same series are similar, or vary in regular gradation according to their position in the series. Thus, in the series of monoatomic alcohols (see table above) each member yields on oxidation, first an aldehyde, then an acid. Each yields a series of compound ethers by the action of acids upon it. The boiling-points of ethylic alcohol and its seven superior homologues are: 78.3, 97.4, 116.8, 137, 157, 176, 195, from which it will be seen that the boiling-point of any one of them can be determined, with a maximum error of less than 1, by taking the mean of those of its neighbors above and below. In this way we may predict, 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 con- 194 TEXT-BOOK OF CHEMISTRY stitution, i. c., their constituent atoms must be similarly arranged within the molecule. (See p. 46.) Isomerism Metamerism Polymerism. Two substances are said to be isomeric, or to be isomeres of each other, when they have the same percentage composition. If, for instance, we analyze acetic acid, formic aldehyde and methyl formate, we find that each body consists of C, and H, in the following proportions: Carbon 40 = 12 Oxygen 53.33 = 16 Hydrogen 6.67 = 2 100.00 30 This identity of percentage composition may occur in two ways. The three substances may each contain the same number of each kind of atom in a molecule ; or they may contain in their several molecules the same kinds of atoms in multiple proportions. In the above ex- ample each substance may have the formula, CH 2 ; or one may have that formula and the others, C 2 H 4 2 , C 3 H 3 , C 4 H 8 4 , C 5 H 10 5 , etc. When two or more substances have the same percentage com- position and the same molecular weight they are said to be meta- meric. When they have the same percentage composition and their molecular weights are simple multiples of the lowest molecular weight represented by that percentage composition, they are said to be polymeric. Other conditions of isomerism will be considered later (see space isomerism, p. 238, and place isomerism, pp. 260, 337). In order to determine the composition (the empirical formula) of an organic substance, two factors are therefore necessary: the per- centage composition and the molecular weight. Elementary Organic Analysis. The first step in an analysis to determine the composition of an organic substance is a qualitative analysis to identify the elements existing in the molecule. This having been done, the quantitative analysis is next in order. The simplest case is where the substance is a hydrocarbon, i.e., a compound of carbon and hydrogen only. The determination of both elements is made in one operation, by taking advantage of the fact that when a compound containing carbon and hydrogen is heated with cupric oxide all the carbon is converted into C0 2 , and all the hydrogen into H 2 0. Thus, if C 2 H 6 0+ 6CuO=2C0 2 -f 3H 2 0+6Cu, 46 parts of alcohol will produce 88 pts. of carbon dioxide and 54 pts. of water. The apparatus required consists of a tube of difficultly fusible glass, called a combustion tube, about 60 cent, long, drawn out to a point and closed at one end, a "combustion furnace," in which this tube may be heated, and tin- absorbing apparatus referred to below. A weighed quantity of the substance of COMPOUNDS OF CARBON 195 which a "combustion" is to be made (sealed in a small glass bulb if liquid) is placed in the closed end of the combustion tube, a Fig. 17, along with the requisite quantity of recently ignited cupric oxide, leaving space tor the passage of the gases produced. The tube is then placed in the furnace and its open end connected with a U tube, &, filled with fused CaCl 2 , or with frag- ments of pumice moistened with concentrated H 2 S0 4 , whose weight has been determined, and whose purpose it is to absorb the H 2 produced. This first U tube is connected with a "Liebig's bulb" containing a strong solution of KOH, c, and this in turn with another U tube in all respects similar to the first, d, both c and d having been previously weighed. The purpose of c is to absorb the C0 2 produced, that of d to retain water carried over from c by the current of gas. The combustion tube is then carefully heated until the evolution of gases ceases, when the closed, drawn-out end of the tube is broken and connected with a gasometer containing pure, dry oxygen, a current of which is passed slowly through the apparatus to bring the last portions of the products of combustion into the absorbing apparatus. Finally the U tubes and the KOH bulb are again weighed. The increase in weight of 6 is the \ FIG. 17. weight of H 2 O produced, every 9 parts of which represent 1 part of H. The increase in weight of c and d is the weight of CO 2 produced, every 44 parts of which represent 12 parts of C. If the substance analyzed contains N, Cl, Br or I, a heated column of pure metallic Cu is interposed toward the open end of the combustion tube, to reduce any oxides of N produced to N, and to retain the Cl, Br or I. If the substance contains S, a layer of lead peroxide is similarly placed to retain the S and PbS0 4 . If the substance consists of C, H and 0, the C and H are determined in the manner above described, and the difference between the sum of their weights and that of the substance burnt is the amount of O. Nitrogen is most readily determined by the method of Kjeldahl. A known weight of the substance is dissolved by heating it in concentrated H 2 S0 4 . Potassium permanganate is then added until the mixture is green. The N contained in the substance is thus converted into ammonia. The strongly acid liquid is diluted, rendered alkaline by addition of NaOH, and the NH 3 is dis- tilled over into a receiver containing a known quantity of acid. The amount of NH 3 produced is calculated from the amount of acid neutralized, and every 17 parts of NH 3 represent 14 parts of N. In the analysis of nitro- and cyano- gen compounds sugar is added, and in that of nitrates, benzoic acid. Determination of Molecular Weights. The percentage compo- sition having been determined, the simplest corresponding ratio of the atoms in the molecule is obtained by dividing. the percentage of each clement by its atomic weight. Thus if analyses are made of formic 196 TEXT-BOOK OF CHEMISTRY aldehyde, acetic acid, methyl formate, lactic acid and glucose, the results in each case will be: Carbon 40.00 per cent. -=- 12 = 3.33 = 1 Hydrogen 6.67 " " -=- 1 = 6.67 = 2 Oxygen 53.33 " " -f. 16 = 3.33 = 1 and the simplest empirical formula of all of the substances mentioned is therefore CH 2 0. The molecular weight of formic aldehyde is 30; its formula is therefore CH 2 0( 12+2+16). The molecular weights of acetic acid and of methyl formate are 60: they, therefore, each have the formula C 2 H 4 2 . The molecular weight of lactic acid is 90 and that of glucose 180: the formula of the former is, therefore, C 3 H 6 3 , and that of the latter C 6 H 12 6 . If the substance is one which can be vaporized without decom- position, its molecular weight is derived from its specific gravity as referred to hydrogen. The process for determining the specific gravity now generally adopted is that of Victor Meyer. Determination of Constitution. The identity and properties of organic compounds depend not only upon their composition, i.e., the number and kind of atoms composing the molecule, but also upon their constitution, i.e., the arrangement of the atoms in the molecule (see p. 46). The constitution of a substance is determined by a study of the methods of its formation, of the products of its decom- position, and of the substances produced by the introduction of other elements or groups into its molecule. A statement of the more important principles, and one or two examples, must suffice here, the subject being further developed in the sequel. The carbon atom is quadrivalent in almost all, if not in all its compounds. In the few in which it is considered as bivalent, as in carbon monoxide, CO, and the isonitrils, (C 2 H 5 ) N=C, the oxygen may be considered to be quadrivalent, and the nitrogen quinquiva- lent, in which case the carbon would be quadrivalent. The carbon atoms may unite with each other in three ways: (1) Two carbon atoms may exchange a single valence in their union, forming a hexavalent group, = C = ; (2) they may unite with exchange of two valences, forming a quadrivalent group, z=C=C ; or, (3) they may unite with exchange of three valences, forming a bivalent group, C = C . These are referred to as single, double and treble linkages, respectively. Those compounds in which all of the linkages are single, and in which all of the possible valences of the constituent atoms are satisfied are saturated compounds. No other atom or radical can be intro- duced into a saturated molecule except by substitution, i.e., by caus- ing the introduced atom or radical to take the place of some other, or others, of cquivjilcnt valence, simultaneously removed. Thus, when chloroform (itself a substituted di-rivntive of marsh gas, CHJ is COMPOUNDS OP CARBON 197 converted into carbon tetrachloride, the remaining hydrogen is re- moved as hydrochloric acid: CHC1 3 +C1 2 =CC1 4 +HC1. Only such substances as contain two carbon atoms doubly or trebly linked, =C=C= or C = C , are usually considered as unsaturated compounds. Such compounds may be modified both by substitution and by addition, i. e., by breaking out the double or treble linkages and the introduction of two new univalents, or one bivalent, for each linkage so liberated. Thus, ethylene yields ethylene chloride by addition: H 2 C:CH 2 +C1 2 =C1H 2 C.CH 2 C1; or, by substitu- tion and addition, carbon hexachloride : H 2 C :CH 2 -|-5C1 2 =C1 3 C.CC1 3 +4HC1. In the reactions referred to above in which chlorine is substituted for hydrogen, it is not only added to the molecule operated upon, but also removes hydrogen by combining with it, and hence two atoms of chlorine are required for each atom of hydrogen removed. Similarly, when removes H 2 , in oxidations, two atoms of oxygen are required for each two atoms of hydrogen removed, as when alcohol is oxidized to acetic acid: C 2 H f) 0+0 2 =C 2 H 4 2 +H 2 0. Consequently in oxida- tions an even number of hydrogen atoms is always removed. The tendency to the formation of water is so strong that in reactions in which two or more hydroxyl groups should unite with the same carbon atom, water almost invariably splits off and oxygen unites doubly with the carbon. Thus caustic potash does not act upon ethidene chloride to produce a glycol according to the equation : CH 3 .CHC1 2 +2KOH=CH 3 CH ( OH ) 2 +2KCl But to produce an aldehyde according to the equation: GH 3 .CHC1 2 +2KOH=CH 3 CHO+H 2 0+2KC1. Exceptions to this rule occur when the carbon atom is linked to another carbon atom contained in a highly oxidized or halide group, as in the compounds : COOH CC1 8 COOH H J,/OH Hfl/ OH rl/OH LC \OH HC \OH |\OH COOH Glyoxalic acid. ' Chloral hydrate. Mesoxalic acid. Usually when an atom or group replaces another in a compound it occupies the position vacated by that which is removed, as when alcohol is formed by the action of caustic potash upon ethyl iodide: CH 3 .CH 2 I+KOH=CH 3 .CH 2 OH+KL There is an exception to this rule when an unsaturated compound may yield either another unsaturated compound in obedience to the rule or an isomeric saturated compound in violation of it, the more stable saturated compound is formed. Thus the hydration of vinyl bromide, CH 2 :CHBr, does not produce vinyl alcohol, CH 2 :CHOH, but its isomere : aldehyde, CH 3 CHO. Indeed, unsaturated compounds 198 TEXT-BOOK OF CHEMISTRY are frequently converted into saturated isomeres by intramolecular transposition of atoms by mere application of heat. The genesis of ethylic alcohol from the action of caustic potasli upon ethyl iodide : CH 3 CH 2 I+KOH=CH 3 .CH 2 OH+KI, shows that the alcohol contains the univalent group CH 2 OH, or H OH \ c / / C \ H which, on oxidation, may lose two atoms of hydrogen with formation of either one of the two univalent groups CHO, or COOH ; either C \ or 0=C<^ which occur in the products of oxidation of ethylic alcohol : aldehyde and acetic acid. The groups CH 2 OH, CHO and COOH, referred to above, are ex- amples of the so-called characterizing groups which exist in the molecules of different classes of substances. The following are the more commonly recurring characterizing groups, and the classes of substances in which they occur: (CH 2 OH)' = HO/ C \ B in P rimai 7 alcohols, called methoxyl, (CHOH)" = H Q/ C (COH)'" = ;C.OH (CHO)' =0=C( (CO)" =0:C: (COOH)' = O=- " secondary alcohols, " tertiary alcohols, " aldehydes, " ketones, called carlonyl,* " acids, called carboxyl, (S0 2 OH)' = }}S/ OH " sulphonic acids, " sulphones, " amido compounds, " imido compounds, " nitro compounds, " nitroso compounds. Nomenclature of Organic Compounds. The vast number and great variety of structure of organic compounds make it difficult to * Thin A.TOIIP also exists in other compound*, as In the aldehydes and acids in the manner in- dicated in the text, and In cuiii|M.mids. such as carbonyl chloride. COCl... urea, N H...CO. M I.,, etc. (SO,)" _ v \\ o_ ~~O// (NH,)' = H a :N. (NH)" = H.N: (NO,)' _o\\ N ~o// N (NO)' = O:N. COMPOUNDS OF CARBON 199 devise a system of nomenclature which will apply to the more com- plex derivatives without producing names which are most complicated and difficult of pronunciation. Indeed, in view of the constantly increasing number of carbon compounds, no complete system of no- menclature is as yet possible. The most recent attempt to formulate one is that of the Geneva "Convention of 1892. In this system the names of the hydrocarbons serve as the roots from which the names of their derivatives are constructed by the addition of syllables indi- cating the function (see p. 208) of the substance. Thus the alcohols are indicated by the syllable ol, the aldehydes by al, the ketones by on, and the acids by the word acid. The * ' Geneva ' ' name of ethylic alco- hol would be ethanol, that of acetic aldehyde ethanal and that of acetic acid etlian-acid. These names have not come into general use. In the nomenclature generally followed the name of a substance is made up of the name of that of the class, or "function," to which the substance belongs, as acid, alcohol, ketone, ester, etc., to which is added a qualifying word derived from the origin of th-B body, as lactic acid, acetic acid, etc.. or from its composition, as methylic alco- hol, ethylic ether, etc., and the names of any radicals which have been introduced into the molecule of the parent compound. Thus the name of the substance COOH.CH 2 (NH.CH 3 ) is methyl-amido-acetic acid, in which "acetic acid" indicates that it is derived from acetic acid, COOH.CH 3 , the syllable amido that NH 2 has been substituted for H in the CH 3 of the acid, and methyl that CH 3 has been substi- tuted for H in NH 2 . The names of the univalent radicals terminate in yl, as methyl (CH 8 )', ethyl (C 2 H 5 )', acetyl (C 2 H 3 0)', etc. Those of bivalent radi- cals terminate in ene, as methylene, (CH 2 )", ethidene (C 2 H 4 )", etc., and those of the trivalent radicals in enyl, or in ine, as methenyl or methine (CH)'", ethemjl or ethine (C 2 H 8 )'", etc. Classification of the Carbon Compounds. The hydrocarbons, consisting of carbon and hydrogen only, constitute the framework of the classification adopted, all other carbon compounds being con- sidered as derivable from the hydrocarbons by substitution or by addition. Carbon compounds are divided into two great classes, differen- tiated by the manner in which the carbon atoms are linked together : A. OPEN CHAIN COMPOUNDS, also called acyclic, fatty, or aliphatic compounds. In these compounds the carbon atoms are attached to each other in an open or arborescent chain, in which two or more carbon atoms are linked to but one other carbon atom, as in the compounds : H H H H H H /CH 2 .CH 8 H C C C C C C H CH 3 .CH 2 .CH I I I I I I \CH. H H H H H H 200 TEXT-BOOK OF CHEMISTRY In the hydrocarbons of this class the number of hydrogen atoms, or this number, plus 'the number of univalent atoms that can be in- troduced into the molecule by addition, is equal to twice the number of carbon atoms plus two. B. CLOSED CHAIN COMPOUNDS, also called cyclic or aromatic com- pounds. These compounds contain one or more closed chains, rings, or nuclei in which each carbon atom is linked to at least two other carbon atoms, or their equivalent, as in the compounds: H H, H H A J ^ i //\ /\ /\\ /\\ H C C H H 2 =C C=H 2 H C C C H I H H H H C C H H 2 =C C C C C H H C C C H \\/ \/\ i i r \// \// C NHHHH CO i I I.I I' 11 -tl XI Benzene. Coniine Naphthalene. The closed chain compounds are subdivided into two classes : I. Carbocyclic compounds, in which the ring or rings consist of carbon atoms exclusively, as in benzene and naphthalene, and II. Heterocyclic compounds, in which atoms of elements other than carbon enter into the composition of the ring, as in confine. OPEN CHAIN, ALIPHATIC, ACYCLIC OR FATTY COMPOUNDS. HYDROCARBONS. Six series are known : A. Methane, or Paraffin Series. These are saturated com- pounds and have the algebraic formula, CnH2n+2. Their names ter- minate in "ane," e.g., Butane, CH 3 .CH 2 CH 2 .CH 3 . B. Olefine Series, containing two doubly-linked carbon atoms. General formula CnH2n. Their names terminate in "ene," e.g., Butene, CH 2 :CH.CH 2 CH 3 . C. Acetylene Series, containing two trebly-linked carbon atoms. Algebraic formula, CnH2-2. Their names terminate in "ine," e.g., Propine, CH!C.CH 3 . D. Diolefine Series, containing two pairs of doubly-linked car- bon atoms. Algebraic formula, CnH2-2, isomeric with the members of the acetylene series. Their names terminate in "diene," e.g., Propadiene, CH 2 :C :CH 2 . Trienes are also known, containing three pairs of doubly-linked carbon atoms, e.g., Octatriene, CH 2 :CH.- CH 2 .CH 2 .CH :CH.CH :CH 2 . E. Olefine-acetylene Series, containing both doubly- and trebly- linked carbon atoms. General formula, CnH2n-4. Their names ter- minate in "one," e.g., Butone, H 2 C:CH.CiCH. F. Diacetylene Series, containing two pairs of trebly-linked carbon atoms. Algebraic formula, CnH2-6. Their names are con- structed by prefixing the syllable "di" to the name of the hydrocar- bon of series C, from which they are derivable by fusion and elimi- nation of H 2 or its equivalent, e.g., Diacetylene, HCiC.CiCH. The sixth terms, of which there are two isomeres: Dipropargyl, HC. : C.CH 2 .CH 2 .CiCH, and Dimethyl diacetylene, H 3 C.CiC.C;C.CH 3 , are isomeric with benzene, the most important of the closed chain hydrocarbons. SATURATED COMPOUNDS METHANE SERIES. The hydrocarbons of the methane series are saturated, as are also most of the compounds derived from them. There are, however, certain of their derivatives, classed here for convenience, which con- tain either a doubly-linked oxygen atom (the aldehydes and ketones) or a trivalent nitrogen atom (the amines, amides, etc.), which form addition products and are, therefore, strictly speaking, unsaturated compounds. 201 202 TEXT-BOOK OF CHEMISTRY HYDROCARBONS. The saturated hydrocarbons at present known extend in unbroken series from methane, CH 4 , to tetracosane, C 24 H 50 ; and above that some members are known as high as dimyricyl, C 60 H 122 . The alge- braic formula of the series is CnH2n+2. They are called paraffins because of their great stability (parum=\itt\e, aj^nw^affinity) ; and also alkanes. They are also considered as the hydrides of the alco- holic radicals, CnEbn+i, methyl, ethyl, etc., which are called alkyls. In the higher terms of the series, above the third, there exist two or more isomeres, increasing progressively in number with an in- creasing number of carbon atoms. Thus there are three having the empirical formula, C 5 H 12 : (1) CH 8 .CH 2 .CH 2 .CH 2 .CH 8 , (3) CH 3 \ (2) CH 8 \ f , HrH rH , CH 3 C.CH,. C H 3 / CH - CH " CH > and ' CH 3 / Hydrocarbons and their derivatives having the "unbranched" structure shown in formula (1) above, are designated as normal compounds; those derived from (2) are called iso compounds; and those derived from (3) meso compounds. The number of possible isomeres increases rapidly with an in- creasing number of carbon atoms. It has been calculated that the number of possible isomeres with increasing values of n are as follows : n = 1 n = 2 n = 3 n = 4 n = 5 n = 6 111235 n = 7 n = S n = 9 n = 10 n=ll n=12 9 18 35 75 159 357 Many of these hydrocarbons exist in nature, in petroleum, and in the gases accompanying it. They may be produced by the follow- ing general reactions: (1) By the action of finely-divided zinc, silver or copper, or of sodium either alone, at elevated temperatures, or in the presence of H 2 0, upon the corresponding iodides: 2C 2 H 5 I+Zn 2 +2H 2 0=ZnH 2 2 +ZnI 2 +2C 2 H G , or, 2C 2 H 5 I+Na 2 =2NaI+C 4 H 10 (2) By electrolysis of the corresponding fatty acid: 2C 2 H 4 2 =2C0 2 +H 2 +C 2 H 6 (3) By heating the salts of the fatty acids with soda-lime: CH 3 .COONa-fNaOH=Na 2 C0 3 +CH 4 (4) By the action of the organo-zincic derivative upon the iodide of the alcoholic radical, or upon the corresponding define iodide. HYDROCARBONS 203 (5) By the action of highly concentrated hydriodic acid at 275- 300 upon hydrocarbons of the ethene and ethine series, upon alco- hols, amines, etc. This is a method of hydrogenation applicable in many other cases. (6) By the action of alkyl magnesium halides upon ammonia, amines, or phenylhydrazine : NH 3 +R.MgX=H 2 N.MgX+RH (7) By the destructive distillation of many organic substances. General Properties. They are gaseous, liquid, or solid, and have sp. gr. and boiling points increasing with the number of C atoms. The first four members are gaseous at the ordinary temperature, those above C 15 H 32 are crystalline solids; the intermediate ones are color- less liquids. They are lighter than H 2 O, neutral, insoluble in H 2 0, soluble in alcohol, ether, and in liquid hydrocarbons. Their odor is faint and not unpleasant. Chlorine and bromine decempose them, with formation of products of substitution. They are inflammable and burn with a luminous flame. Nitric acid forms nitro-derivatives with the higher terms. Methyl Hydride Methane Marsh-gas Fire-damp CH 4 16 is given off in swamps as a product of decomposition of vegetable matter, in coal mines, and in the gases issuing from the earth in the vicinity of petroleum deposits. It is also formed during putrefac- tion of protein bodies and fermentation of carbohydrates. From these origins it exists in intestinal gases, sometimes to the extent of 26.5 per cent. Coal-gas contains it in the proportion of 36-50 per cent. Preparation. It may be prepared by strongly heating a mixture of sodium acetate with sodium hydroxide and quick-lime: NaC 2 H 3 2 +NaOH:=Na 2 C0 3 +CH 4 Its complete synthesis, which is of theoretic interest, may be effected in several ways: (IX Carbon disulphide is first produced by passing vapor of sulphur over coal, heated to redness: C+S 2 =CS 2 . This may either be passed, along with hydrogen sulphide, over red- hot copper, when: CS 2 +2H 2 S+8Cu=CH 4 +4Cu 2 S, or, (2) it may be converted into carbon tetrachloride by the reaction: CS 2 +3C1 2 =: CC1 4 +S 2 C1 2 ; and this reduced by nascent hydrogen : CCl 4 -]-4H 2 =: CH 4 +4HC1. (3) Carbon monoxide, prepared by heating carbon in a limited quantity of air, is reduced by hydrogen when the two are treated with the induced electric current: CO-|-3H 2 =CH 4 -fH 2 0. (4) Aluminium carbide is decomposed by water according to the equation : C 3 A1^+12H 2 0=:3CH 4 4-2A1 2 ( HO ) 8 . Properties. It is a colorless, odorless, tasteless gas; very spar- ingly soluble in H 2 O ; sp. gr. 0.559A. At high temperatures, it is decomposed into C and H. It burns in air with a pale yellow flame. Mixed with air or it explodes violently on contact with flame, pro- 204 TEXT-BOOK OF CHEMISTRY ducing 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 H atoms are displaced by an equivalent quantity of Cl. In direct sunlight the substitution is accompanied by an explosion. Petroleum. Crude petroleum varies in color from a faintly yellowish tinge to a dark brown, nearly black, with greenish reflections. The lighter- colored varieties 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 consist of normal paraffins (the lowest terms of the series being found in the gases accompanying petroleum and held in solution by the oil under the pressure it supports in natural pockets), besides hydrocarbons of the olefine, paraffin, and benzene series. They also contain varying quantities of sulphur com- pounds, which communicate a disgusting odor to some oils. 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 products of lowest boiling point are usually consumed, but are sometimes condensed. The principal products of petroleum are: Cymogene, boils at 0, used in ice machines; Rhigolene, a highly inflammable liquid, sp. gr. about 0.60, boils at about 20, used to produce cold by its rapid evaporation. Petroleum ether, boils at 40-50, used as a solvent. Gasolene, boils from 45 to 76, used as a fuel and for the manufacture of "air gas." Naphtha, divided into three grades, C, B, and A, boils from 82.2 to 148.8, used as a solvent for fats, etc., and in the manufacture of "water gas." Sometimes called "safety oil." Benzine, or benzolene, boils from 148 to 160, used as a solvent in making paints and varnishes. The most important product of petroleum is that portion which distils between 176 and 218, 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 37.4, and should not burn at temperatures below 149. The better grades of kerosene have a flash point of from 45 to 65. From the residue remaining after the separation of the kerosene, many other products are obtained. Lubricating oils, of too high boiling-point for use in lamps. Paraffin, a white, crystalline solid, fusible at 45-65, which is used in the arts for a variety of purposes 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 other purposes, as it is not affected by acids or by alkalies. It is odorless, tasteless, insoluble in H 2 O 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, cosmoline, etc., are mixtures of para- ffin and the heavier petroleum oils. Their consistency depends upon the relative proportion of the higher paraffins, of increasing fusing-point, which they con- tain, from the oily petrolatum liquidum (U. S. P.), to the hard petrolatum or petrolatum album (U. S. P.). Like petroleum itself, its various commercial products are not definite compounds, but mixtures of the hydrocarbons of this series. HALOID DERIVATIVES OF THE PARAFFINS. By the action of Cl or Br, upon the paraffins, or by the action of HC1, HBr or HI upon the corresponding hydroxides, the monohydric HALOID DERIVATIVES OF THE PARAFFINS 205 alcohols/ compounds are obtained in which one of the H atoms of the hydrocarbon has been replaced by an atom of Cl, Br or I: C 2 H 6 +Br 2 =:C 2 H 5 Br+HBr, or C 2 H 5 OH+HC1=C 2 H 5 C1+H 2 Or they are more readily obtained by the action of the phosphorus halides, or of the halogen in presence of phosphorus upon the mono- hydric alcohols: CH 3 .CH 2 OH+PC1 5 =CH 3 .CH 2 C1+POC1 3 +HC1 These monohalogen paraffins, or haloid ethers, or haloid esters, or alkyl halides, may also be considered as the chlorides, etc., of the alcoholic radicals, methyl, etc. When Cl is allowed to act upon CH 4 , it replaces a further number of H atoms until finally carbon tetrachloride, CC1 4 , is produced. Considering marsh gas as methyl hydride, CH 3 .H, the first product of substitution is methyl chloride, CH 3 C1; the second monochlor- methyl chloride, CH 2 C1.C1; the third dichlormethyl chloride, or chloroform, CHC1 2 .C1 ; and the fourth carbon tetrachloride, CC1 4 . Similar derivatives are formed with Br and I, and with the other hydrocarbons of the series. Nascent hydrogen reduces all of the halogen derivatives to the parent hydrocarbons: CHC1 3 +3H 2 =CH 4 +3HC1 These compounds are of great service for the introduction of their alkyls into other molecules. Thus, benzene and methyl chloride form methyl benzene: C 6 H 6 +CH 3 C1=C C H 5 .CH 3 +HC1 Caustic potash or soda in alcoholic solution splits off the halogen and water, with formation of an unsaturated hydrocarbon: CH 3 .CHJBr+KOH=CH 2 :CH 2 +KBr+H 2 Heated with aqueous potash the haloid esters produce the cor- responding alcohols: CH 3 .CH 2 Br+KOH=CH 3 .CH 2 OH+KBr Heated with alcoholic solution of potassium cyanide at 100, the haloid esters produce the alkyl cyanides: CH 3 .CH 2 I+KCN=CH 3 .CH 2 .CN+KI They also combine with ammonia to form amines : CH 3 C1+NH 3 =CH 3 .NH 2 +HC1 Methyl Chloride CH 3 C1 50.5 is a colorless gas, slightly solu- ble in H 2 0, and having a sweetish taste and odor. It is prepared commercially by heating trimethylammonium chloride (obtained by distilling beet sugar molasses) : 3N(CH 3 ) 3 HC1=2CH 3 C1+2N(CH 3 ) 3 +NH 2 CH 3 +HC1 206 TEXT-BOOK OF CHEMISTRY It may be condensed to a liquid which boils at 22, in which form it is used in ice machines, as a spray in neuralgia, and as an anesthetic; for the latter uses either alone or mixed with CHC1 3 , C 4 H 10 0, or C 2 H 5 C1. It burns with a greenish flame. Dichlormethane Methene chloride Methylene chloride Monochlormethyl chloride CH 2 C1 2 85 is obtained by the action of Cl upon CH 4 , and by the reduction of CHC1 3 by nascent hydrogen. It is a colorless, oily liquid; boils at 40; sp. gr. 1.36; its odor is similar to that of chloroform ; it is very slightly soluble in H.,0 and is not inflammable. It has been used as an anesthetic, but has been discarded as being less safe than chloroform. Trichlormethane Methcnyl chloride Dichlormethyl chloride Chloroform Chloroformum (U. S. P.) CHC1 3 119.5. Chloroform is manufactured by the action of bleaching powder upon acetone, the reaction being expressed by the equation: 2CO(CH 3 ) 2 +6CaCl(OCl)=2CHCl 3 +2Ca(HO) 2 + (CH 3 COO) 2 Ca+3CaCl 2 It is best obtained pure by heating chloral hydrate with an alkali : C 2 HC1 3 (OH) 2 +KOH=CHC1 3 +HCOOK+H 2 It is a colorless, volatile liquid, having a strong, agreeable, ether- eal odor, and a sweet taste ; sp. gr. 1.497 ; very sparingly soluble in H 2 ; miscible with alcohol and ether in all proportions ; boils at 60.8. It is a good solvent for many substances insoluble in H 2 0, such as phosphorus, 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 2 S0 4 , except after long contact, when HC1 is given off. In direct sunlight Cl converts it into CC1 4 and HC1. The alkalies in aqueous solution do not act upon it, but when heated with them in alcoholic solution, it is decom- posed with formation of chloride and formate of the alkaline metal: CHC1 3 +4KOH=H.COOK+3KC1+2H 2 When perfectly pure it is not altered by exposure to light ; but if it contains compounds of N, even in very minute quantity, it is gradually decomposed by solar action into HC1, Cl and other sub- stances. When used as an anesthetic chloroform should not be colored by agitation with concentrated, colorless sulphuric acid, and should color the latter only faintly yellow, or not at all; and when it is evaporated the remaining film of moisture should have no taste or odor other than those of chloroform. Analytical Characters. (1) Add a little alcoholic solution of potash and 2-3 drops of aniline and warm: the disagreeable odor of isobenzonitrile (q.v.) is produced. (2) Vapor of CHC1 3 , when passed through a red-hot tube, is decomposed with formation of HC1 and HALOID DERIVATIVES OF THE PARAFFINS 207 Cl, the former of which is recognized by the production of a white ppt., soluble in ammonium hydroxide, 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 fi naphthol in a small quantity of KOH solution, warm, and add the suspected liquid; a blue color is produced. (4) Add about 0.3 grm. resorcinol in solution, and 3 gtts. NaOH solution and boil strongly; in the presence of CHC1 3 a red color is produced. But the liquid exhibits no fluorescence (p. 232). 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 sur- faces. Recovery has followed a dose of four ounces, and death has been caused by one drachm, taken into the stomach. Chloroform vapor acts much more energetically, and seems to owe its potency for evil to its paralyzing influence upon the respiratory nerve centers, and upon the cardiac ganglia. While persons suffering from heart disease are particularly susceptible to tfye para- lyzing 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 post-mortem examination. Chloroform is apparently not altered in the system. No chemical antidote for chloroform is known. When it has been swal- lowed, stomach-lavage and emetics are indicated; when taken by inhalation, a free circulation of air should be established about the face; artificial respira- tion and the application of the induced current to the sides of the neck and epigastrium should be resorted to. Carbon Tetrachloride CC1 4 154 is formed by the prolonged action, in sunlight, of Cl upon CH 3 C1 or CHC1 3 ; or more rapidly, by passing Cl, charged with the vapor of carbon disulphide, through a red-hot tube, and purifying the product. It is a colorless, oily liquid, insoluble in H 2 ; soluble in alcohol and in ether; sp. gr. 1.56; boils at 78. Its vapor is decomposed at a red heat into a mixture of the dichloride, C 2 C1 4 , trichloride, C 2 C1 6 , and free Cl. Tribrommethane DibromometJiyl bromide Methenyl bromide Bromoform CHBr 2 .Br 253 is prepared by gradually adding Br to a cold solution of KOH in methyl alcohol until the liquid begins to be colored; and rectifying over CaCl 2 . A colorless, aromatic, sweet liquid; sp. gr. 2.13; boils at 150- 152 ; solidifies at 9 ; sparingly soluble in H 2 ; soluble in alcohol and ether. Boiled with alcoholic KOH it is decomposed in the same way as in CHC1 3 . Its physiological action is similar to that of CHC1 3 . It occurs as an impurity of commercial Br, accompanied by carbon tetrabromide, CBr 4 . Triiodomethane Diiodomethyl iodide MetJienyl iodide lodo- form lodoformum, (U. S. P.) CHLI 394. Formed like CHC1 3 , 208 TEXT-BOOK OF CHEMISTRY and CHBr 3 , by the combined action of KOH 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 2 0, I and ethylic alcohol, and purifying the prod- uct by recrystallization from alcohol. It is also produced from acetone by making a solution containing 50 gm. KI, 6 gm. acetone, and 2 gm. NaOH in 2 L. H 2 and gradually adding a dilute solution of KC1O 3 . Triiodoaldehyde and triiodoacetone are formed as intermediate products. lodoform is a solid, crystallizing in yellow, hexagonal plates, which melt at 120 . It may be sublimed, a portion being decomposed. It is insoluble in water, acids and alkaline solutions; soluble in alco- hol, ether, carbon disulphide, and the fatty and essential oils; the solutions, when exposed to the light, undergo decomposition and assume a violet-red color. It has a sweet taste, and a peculiar, pene- trating odor, resembling, when the vapor is largely diluted with air, that of saffron. When heated with potash a portion is decom- posed into formate 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 2 H 5 C1 64.5. A colorless, ethereal liquid; boils at 11; obtained by passing gaseous HC1 through ethylic alcohol to saturation, and distilling over the water-bath: C 2 H 5 OH+HC1=H 2 0+C 2 H 5 C1 It is now used to produce cold by spraying. The liquid and vapor are readily inflammable. Ethyl Bromide Hydrobromic ether C 2 H 3 Br 109 A colorless, ethereal liquid; boils at 40.7, obtained by the combined action of P and Br on ethylic alcohol. It has been used as an anesthetic in minor surgery. Ethyl Iodide Hydriodic ether CjH 5 I 156 is prepared by placing abso- lute 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; has a powerful, ethereal odor; burns with difficulty. It is largely used in the aniline industry. OXIDATION PRODUCTS OF THE PARAFFINS. Many important and varied classes of compounds are derivable from the paraffins by oxidation: One of these may be considered as derived * from the hydrocarbon by the introduction of an oxygen atom between two of its hydrocarbon groups. Thus from the hydrocarbon butane, CH 3 .CHj.CH 2 .CH 3 we may derive the oxides CH,. * Note: The words "derived" and " obtained" are not used synonymously. One substance is said to he derived from another when there is such relation between their molecular structures that tin' constitutional formula of the more complex may l*> produced from that of the more simple by substitution. A method of obteution is a process by which a substance is manufactured, and does not imply any relation between the molecular structures of the product and parent, al- though such may, and very frequently does, exist. OXIDATION PRODUCTS OF THE PARAFFINS 209 CH 2 .O.CH 2 CH 3 and CH 3 .O.CH 2 .CH 2 .CH 3 . These are the true oxides of the alkyls, and are known as simple and mixed ethers, according as the oxygen atom is symmetrically or unsymmetrically introduced or two oxygen atoms may be thus introduced; as in the formals (p. 232) : CH 3 O.CH,O.CH 3 . Or, in other classes of compounds, an oxygen atom may be interpolated as in the ethers, and one or more of the hydrocarbon groups may be also oxidized. In this manner compounds of very diverse nature are derived: Esters, such as ethyl acetate, CH 3 .CO.O.CH 2 .CH 3 ; acid anhydrides, or acidyl oxides, such as acetic anhy- dride, CH 3 .CO.O.CO.CH 3 ; certain acids, such as diglycollic acid, COOH.CH 2 .- O.CH 2 .COOH, and certain dihydric alcohols, such as diethylene glycol, CH 2 OH.CH 2 .O.CH 2 .CH 2 OH. It will be more convenient to consider "these several classes of compounds after having discussed the other oxidation products. Four other classes are more closely related to each other. They may be considered as being derived from the hydrocarbons in one of two ways; either ( 1 ) By the interpolation or substitution, or both, of an oxygen atom or atoms in one of the groups CH 3 , CH 2 , or CH of the parent hydrocarbon (see formulae on p. 210). Thus: (H 2 :C.H)' becomes (H 2 :CO.OH)'; (0:C.H)' or (O:C.O.H)' (H.C.H)" " (H.C.O.H)" or (C:0)" and (C.H)'" (C.O.H)'" and by the oxidation of a single group in the hydrocarbon: isopentane; (CH 3 ) 2 :CH.CH 2 CH 3 the following products may be obtained: (CH 3 ) 2 (CH 3 ) 2 (CH 3 ) 2 (CH 3 ) 2 (CH 3 ) 2 (CH 3 ) 2 CH CH CH CH CH C.O.H CH 2 CH 2 CH 2 H.C.O.H C:0 CH 2 I 1 | 1 1 1 H 2 jC.O.H O:C.H 0:C.O.H CH 3 CH 3 CH 3 Primary Alcohol. Aldehyde. Acid. Secondary Alcohol Ketone. Tertiary Alcohol. Isobutyl Valeral- Isovaler- Methyl Methyl Dimethyl Carbinol. dehyde. ianic Acid. isopropyl isopropyl ethyl Carbinol. Ketone. Carbinol. (2) Or these compounds may be considered as produced by the substitu- tion of hydroxyls ( OH ) , for one or more of the hydrogen atoms of the hydro- carbon, it being remembered that when a substance is thus produced in which two hydroxyls are attached to the same carbon atom, water separates, except under the circumstances referred to on page 197. Thus from the hydrocarbon: propane, CH 3 .CH 2 .CH 3 , the following products may be derived by substitution in a single hydrocarbon group: CH 3 .CH 2 .C Q|j=:Primary alcohol; CH 3 .CH 2 .C /E QH } 2 -H 2 0=CH 3 .CH 2 .C /** ^Aldehyde ; CH 3 .CH 2 .C; (OH) 3 H 2 0=CH 3 .CH 2 .C ^ H =Acid; CH 3 . ( CH.OH ) .CH 3 =Secondary alcohol ; CH 3 . ( C : [OH] 2 ) .CH 3 H 2 0=CH 3 . ( C : ) .CH 3 =Ketone. When the number of hydroxyls substituted in each hydrocarbon group ex- ceeds one, the number of derivatives increases rapidly with an increasing num- 210 TEXT-BOOK OP CHEMISTRY her of C atoms in the parent hydrocarbon. Thus the second term of the series, CII 3 .CH 3 , yields nine derivatives: I. II. III. CH a OH CH(OH) 2 0:C.H C(OH) 3 O:C.OH I ' H 2 0= | | H,0= | CH 3 CH 3 CH 3 CH 3 CH 3 Kt hylic Acetic Acetic Alcohol. Aldehyde. Acid. IV. V. VI. CH 3 OH CH(OH) 2 0:C.H CH(OH) 2 O:C.H I -H 2 0= | 2H 2 0= | CH 2 OH CH 2 OH H 2 :C.OH CH(OH), O:C.H Klhylene (Myrolyl Glyoxal. Olycol. Aldehyde. VII. VIII. IX. C(OH) S 0:C.OH C(OH) 3 0:C.OH C(OH) 3 0:C.OH H 2 0= I /r/nTTt Trr/ OH 2H 2 0= CH 2 OH H 2 :C.OH "\OH C(OH) 3 O:C.OH Glycollic Glyoxylic Oxalic Acid. Acid. Acid. There are twenty-nine possible derivatives of the third hydrocarbon, CH 3 .CH 2 .CH 3 . The four classes of oxidation products under consideration are: A. The alcohols, subdivided into (a) Primary, containing the group C^QJJ; (b) Secondary, containing the group ^C/QJJ; and (c) Tertiary, containing the group EE C.OH ; B. The aldehydes, containing the group C^Q H ; C. The ketones, containing the group=C=0 ; and // ^\ D. The carboxylic acids, containing the group carboxyl : C ALCOHOLS HYDROCARBON HYDROXIDES. These substances are mainly characterized by their power of entering into double decomposition with acids to form neutral com- pounds, called esters, water being at the same time formed at the expense of both alcohol and acid. They are the hydroxides of hy- drocarbon radicals, the alkyls, and as such resemble the metallic hydroxides, while the esters are the counterparts of the metallic salts : (C 2 H 5 ) ) Q (C 2 H 3 0) ) _ (C 2 H 3 0) ) Q II j I Q Hf C H f C (C 2 H 5 ) \ C 'HP Ethyl hydroxide. Act-tic acid Ethyl acetate. Water. o + Potassium Acetic acid Potassium Water, hydroxide. acetate. ALCOHOLS 211 Or they may be regarded as substances derived from the hydro- carbons by the substitution of one or more hydroxyls for one or more hydrogen atoms. Alcohols containing one OH are designated as monoatomic or monohydric ; those containing two OH groups are diatomic or dihydric, etc. : CH 2 OH CH 2 OH CH 2 OH CH 2 OH CH 2 OH CH 2 OH CH 2 CH 2 CHOH (CHOH) 2 . (CHOH) 3 (CHOH) 4 k CH 2 OH CH 2 OH CH 2 OH CH 2 OH CH 2 OH Propvlic Propyl Glycerol, Erythrol, Arabite, Mannitol, Alcohol, Glycol, Triatomic. Tetratomic. Pentatomic. Hexatomic. Monoatomic. Diatomic, MONOATOMIC, OR MONOHYDRIC ALCOHOLS. Beginning with the third member of the series, an increasing number of isomeres of the higher terms are known. I. Some of these alcohols yield on oxidation, first, an aldehyde containing the group (CHO)' and then an acid containing the group (COOH)', both aldehyde and acid containing the same number of carbon atoms as the alcohol. These alcohols contain the character- izing group (CH 2 OH)', and are called primary alcohols, e.g., ethylic alcohol: CH 3 .CH 2 OH. II. Other monoatomic alcohols yield on oxidation not an aldehyde or an acid, but a ketone, containing the group (CO)" and the same number of carbon atoms as the alcohol. These alcohols contain the characterizing group (CHOH)", and are called secondary alcohols, or 4soalcohols, e.g., Isopropyl alcohol : CH 3 .CHOH.CH 3 . III. Still other alcohols yield on oxidation either two or more acids, or an acid and a ketone, whose molecules contain a less number of carbon atoms than the alcohol from which they were derived. These alcohols contain the characterizing group (COH)'", and are called tertiary alcohols, e.g., Tertiary butyl alcohol, (CH 3 ) 3 :COH. The monohydric alcohols are also the hydroxides of *Jie alkyls (p. 202). Nomenclature. Names of alcohols terminate in ol; and the termination ol is reserved for the names of alcohols and of phenols. The " Geneva " names of the monohydric alcohols are derived from tho^e 01 the corresponding hydrocar- bons by the substitution of the syllable ol for the terminal e: Thus H.CH 2 OH is methanol; CH 3 .CH 2 OH etlnnol; CH 3 .CH 2 CH 2 OH, 1-propanol; CH 3 .CHOH.CH 3 , 2-propanol, etc. Kolbe's system of naming the monoatomic alcohols is more generally fol- lowed. It refers the names of the higher alcohols back to that of the first, H.CH 2 OH, which is called carl'nol; the names of the radicals contained in the superior homologues being preL'ed to the word "carbinol" in the construction of their names. Thus the grapf 'c formulae and carbinol names of the eight possible amylic alcohols are as i Mows: 212 TEXT-BOOK OF CHEMISTRY Primary. Secondary. (1) CH 3 .CH 2 .CH 2 .CH 2 .CH 2 OH ,., CH : \ ' ( *i i Butyl Carbinol. Ul : (Normal ainyllc alcohol.) Diethyl t'arbinol. (2) ~g s ^ CH.CH 2 .CH 2 OH (fi) Isobutyl Carbinol. (Amylic alcohol of Methyl n-propyl Carbinol. fermentation.) < 3 > CH,H> H - CH OH (7) CT;> CH / Secondary butyl Carbinol. Methyl Isopropyl Carbinol. (Active amyiic alcohol). Tertiary. CH 3 \ CH 3 \ (4) CH 3 C.CH 2 OH (8) CH 3 C.OH CH 3 / CH 3 .CH 2 / Tertiary butyl Carbinol. Dimethyl ethyl Carbinol. Of the above, numbers 1, 5 and 6 are derived from the normal paraffin (1, p. 202); numbers 2, 3, 7 and 8 from the isoparaffin (2), and number 4 from the mesoparaffin (3). . General Methods of Formation. (1) By the action of freshly precipitated, moist silver hydroxide upon the haloid esters: C 2 H 5 I+AgOH=C 2 H 5 OH+AgI (2) By the saponification of their esters by caustic potash: C 2 H 8 2 .C 2 H B +KOH=C 2 H 5 .OH+C 2 H 8 2 K (3) Primary alcohols are produced by the reduction of aldehydes, acid chlorides, or anhydrides : C 2 H 5 .CHO+H 2 =C 2 H 5 .CH 2 OH, or C 2 H 5 .COC1+2H 2 =C 2 H 5 .CH,OH+HC1, or (CH 3 CO) 2 0+2H 2 =CH 3 .CH 2 OH+CH 3 .COOH (4) By the action of nitrous acid upon the primary amines: CH 3 .CH 2 .NH 2 +HN0 2 =CH 3 .CH 2 OH+N 2 +H 2 (5) By the action of trioxymethylene upon the alkyl magnesium halides (p. 291) ; the alcohol next above the alkyl contained in the organo-metallic compound being formed. This reaction, after the trioxymethylene splits to formic aldehyde (p. 228), takes place in two stages. A condensation product is first formed: CH 3 .CH 2 .Mg.Br.+H.CHO=CH 3 .CH 2 .CH 2 .O.Mg.Br. And this is then hydrolyzed : CH 3 .CH 2 .CH 2 .O.Mg.Br.+H 2 0=CH 3 .CH 2 .CH 2 OH.+HO.Mg.Br. (p. 291). (6) Secondary alcohols are formed by the reduction of ketones: CH 3 .CO.CH 3 +H 2 =CH 3 .CHOH.CH 3 . (7) With aldehydes higher than formic aldehyde, alkyl mag- ALCOHOLS 213 nesium halides produce secondary alcohols, the reactions occurring in two phases as in (5) : CH 3 .Mg.I.+CH 3 .CHO.=CH 3 .CH(CH 3 )O.Mg.I. and CH 3 .CH(CH 3 ).O.Mg.I.+H 2 0=CH 3 .CHOH.CH 3 +HO.Mg.I. (8) Tertiary alcohols are produced by the action of moist silver hydroxide upon tertiary alkyl iodides. Thus tertiary butyl iodide yields tertiary butyl alcohol: g> CI.CH.+ AgOH= g> C ( OH) -CH 3 +AgI (9) With ketones the alkyl magnesium halides produce tertiary alcohol by reactions similar to those given (in 5 and 7) : CH 3 .Mg.Br+CH 3 .CO.CH 3 =:(CH 3 ) 2 =(CH 3 ).O.Mg.Br. and (CH 3 ) 2 :C(CH 3 ).O.Mg.Br.+H 2 0=(CH 3 ) 3 = COH+HO.Mg.Br. (10) Acetyl chloride or anhydride reacts violently with alkyl magnesium halides. At suitable temperature this reaction occurs in two stages: CH 3 .CO.Cl+CH 3 .MgCl=(CH 3 ) 2 :CC1.0.MgCl. and (CH 3 ) 2 :CC1.0.Mg.Cl+CH 3 .MgCl=(CH 3 ) 3 iCO.MgCl+MgCl 2 The product when hydrolyzed yields a tertiary alcohol: (CH 3 ) 3 . : CO.MgCl+H 2 0=(CH 3 ) 3 !COH+HO.MgCl. (See p. 389.) (11) Tertiary alcohols are also produced by interaction of alkyl magnesium halides with esters of monobasic acids (except formic), or with carbonyl chloride. Formic esters yield secondary alcohols (p. 290). General Reactions. (1) The monohydric alcohols react with metallic Na or K to form double oxides, called alcoholates : 2CH 3 .CH 2 OH+Na 2 =H 2 +2CH 3 .CH 2 .O.Na. (2) When heated with acids they form esters: CH 3 .CH.,OH+H 2 S0 4 =CH 3 .CH 2 .HS0 4 +H 2 0, or 2CH 3 .CH 2 OH+H 2 S0 4 == ( CH 3 .CH 2 ) 2 S0 4 +2H 2 (3) When heated with hydracids they form alkyl halides: CH S .CH 2 OH+HC1=CH 3 .CH 2 C1+H 2 ; which, in turn, when reduced by nascent hydrogen, regenerate the parent hydrocarbon: CH 3 CH 2 C1+H 2 =CH 3 .CH 3 +HC1 (4) Their products of oxidation vary according as they are primary, secondary or tertiary (see above) : Primary: 2CH 8 .GH 2 OH+0 2 ==2CH 8 .CfiO-f2H 2 O, and CH S .CH 3 OH+0 2 =CH 3 .COOH+H 2 214 TEXT-BOOK OF CHEMISTRY Secondary: 2CH 3 .CHOH.CH 3 +0 2 =2CH 3 .CO.CH 3 +2H 2 Tertiary : 2 ( CH 3 ) 3 .COH+30 2 =2CH 3 .CO.CH 3 +2H.COOH+2H 2 0, then CH 3 .CO.CH 3 +20 2 =CH 3 .COOH+C0 2 +H 2 0, and 2H.COOH+0 2 =2C0 2 +2H 2 0. Methyl Hydroxide Carbinol Pyroxylic spirit Methylic alco- holWood alcohol Wood spirit H.CH 2 OH=32 may be formed from marsh-gas, CH 3 H, by first converting it into the iodide, and acting upon this with potassium hydroxide : CH 3 I+KOH=KI+H.CH 2 OH It is usually obtained by the destructive distillation of wood. The pure hydroxide can only be obtained by decomposing a crystal- line compound, such as methyl oxalate, and rectifying the product until the boiling-point is constant at 66.5. Pure methyl alcohol is a colorless liquid, having an ethereal and alcoholic odor, and a sharp, burning taste; sp. gr. 0.814 at 0; boils at 66.5; burns with a pale flame, giving less heat than that of ethylic alcohol; mixes with water, alcohol, and ether in all pro- portions; is a good solvent of resinous substances, and also dissolves sulphur, phosphorus, potash, and soda. Methyl hydroxide is not affected by exposure to air under ordinary circumstances, but in the presence of platinum-black it is oxidized, with formation of the corresponding aldehyde, formaldehyde, and acid, formic acid. Hot HN0 3 decomposes it with formation of nitrous fumes, formic acid and methyl nitrate. It is acted upon by H 2 S0 4 in the same way as ethyl alcohol. The organic acids form methyl esters with it. Methylated spirit is ethyl alcohol containing one-ninth its vol- ume of wood spirit. Ethyl Hydroxide Ethylic alcohol Methyl carbinol Vinic alcohol Alcohol Spirits of wine CH 3 .CH 2 OH 46. Preparation. Industrially alcohol and alcoholic liquids are ob- tained from substances rich in starch or glucose. The manufacture of alcohol consists of three distinct processes: (1) the conversion of starch into sugar; (2) the fermentation of the saccharine liquid; (3) the separation, by distillation, of the alcohol formed by fermentation. ( 1 ) 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 germination, 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 \vjiter. ALCOHOLS 215 and the mass maintained at a temperature of 65-70 for two to three hours, during which the diastase rapidly converts the starch into dextrin, and this in turn into maltose and glucose. (2) The saccharine fluid, or wort, 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 takes place, the principal one of which is the splitting up of the glucose into carbon dioxide and alcohol: There are formed at the same time small quantities of glycerol, succinic acid, and propylic, butylic, and amylic alcohols. (3) 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. 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 2 0, and when pure or absolute alcohol is required, the commercial product must be mixed with some hygroscopic 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 originally applied to alcoholic fermentation, by reason of the bub- bling of the saccharine liquid caused by the escape of C0 2 ; subse- quently 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 heterogeneous processes; and some writers distinguish between "true" and "false" fermentation. It is best to limit the appli- cation of the term to those decompositions designated as true fer- mentations. Fermentation is a decomposition of an organic substance, pro- duced by the processes of nutrition of a low form of animal or vegetable life. The true ferments are therefore all organized beings, such as torula cerevisice, producing alcoholic fermentation; penicillium glau- cum, producing lactic acid fermentation; and mycoderma aceti, pro- ducing acetic acid fermentation. Acetic acid fermentation. The micro-organism, which is present in the air, causes the alcohol to take up oxygen from the air; acetic acid is produced : C 2 H 5 OH+0 2 =:CH 3 .COOH+H 2 216 TEXT-BOOK OF CHEMISTRY Lactic acid fermentation. The micro-organism, which is present in the air, gets into the milk and converts the lactose into lactic acid : C 12 H 22 11 +H 2 0=4C 3 H 6 3 Butyric acid fermentation. This is brought about when decaying cheese and sour milk arc brought together; the lactic acid is con- verted into butyric acid by the butyric ferment which is present in the cheese: 2C 3 H 6 3 =C 3 H 7 .COOH+2C0 2 +2H 2 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. The unorganized fer- ments, such as diastase, pepsin, etc., are called enzymes. An interesting total synthesis of alcohol is from calcium carbide, water and hydrogen. Acetylene is formed by the action of water upon calcium carbide: CaC 2 +2H 2 0=CaH 2 2 +CJI 2 Vapors of acetylene and water, heated together to 325 unite to form aldehyde: C 2 H 2 +H 2 0=CHO.CH 3 And nascent hydrogen converts aldehyde into alcohol : CHO.CH 3 +H 2 =CH 2 OH.CH 3 Properties. Alcohol is a thin, colorless, transparent liquid, hav- ing a spirituous odor and a sharp, burning taste; sp. gr. 0.8095 at 0, 0.7939 at 15; it boils at 78.5, and solidifies at 130.5. At temperatures below 90 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 abso- lute alcohol only remains such for a very short time after its prepara- tion. It is to this power of attracting H 2 O that alcohol owes its preservative power for animal substances. It is a very useful solvent, dissolving a number of gases, many mineral and organic acids and alkalies, most of the chlorides and carbonates, some of the nitrates, and the essences and resins. The sulphates are insoluble in alcohol. Alcoholic solutions of fixed medicinal substances arc called tinctures; those of volatile principles, spirits. The action of oxygon upon alcohol varies according to the con- ditions. I'mler 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 2 H e O+30 2 =2C0 2 +3H 2 ALCOHOLS 217 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 : CH 3 .CH 2 OH+O 2 =CH 3 .COOH+H 2 a reaction which is utilized in the manufacture of acetic acid and vinegar. If the oxidation is still further limited, aldehyde is formed : 2CH 3 .CH 2 OH+0 2 =2CH 3 .CHO+2H 2 If vapor of alcohol is passed through a tube filled with platinum sponge and heated to redness, or if a coil of heated platinum wire is introduced into an atmosphere of alcohol vapor, the products of oxidation are quite numerous : among them are water, ethylene, alde- hyde, acetylene, carbon monoxide, and acetal. Heated platinum wire introduced into vapor of alcohol continues to glow by the heat result- ing from the oxidation, a fact which has been utilized in the thermo- cautery. Chlorine and bromine act energetically upon alcohol, producing a number of chlorinated and brominated derivatives, the final products being chloral and bromal. If the action of Cl is moderated, alde- hyde and HC1 are first produced. Iodine acts quite slowly in the cold but old solutions of I in alcohol (Tr. iodine) are found to con- tain HI, ethyl iodide, and other imperfectly studied products. In the presence of an alkali, I acts upon alcohol to produce iodoform, which is also formed under like conditions from aldehyde or acetone. Potassium and sodium dissolve in alcohol with evolution of H; upon cooling, a white solid crystallizes, which is the double oxide of ethyl and the alkali metal, and is known as potassium or sodium ethylate or alcoholate. 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 cor- responding esters and the ethers.) The hydroxides of the alkali metals dissolve in alcohol, but react upon it slowly; the solution turns brown and contains an acetate. If alcohol is gently heated with HN0 3 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 : abso- lute alcohol is pure alcohol, C 2 H 6 0. It is not purchasable, and must be made as required. Alcohol dehydratum (U. S. P.) contains not less than 99 per cent, by weight of C 2 H 5 OH. The so-called absolute alcohol of the shops is rarely stronger than 98 per cent. Alcohol (U. S. P.), sp. gr. 0.820, contains 94 per cent, by volume, and spiritus rectificatus, sp. gr. 0.838, contains 84 per cent. This is the ordinary rectified spirit used in the arts. Alcohol dilutum (U. S. P.) 218 TEXT-BOOK OF CHEMISTRY used in the preparation of tinctures, contains 41 per cent. It is of about the same strength as the proof spirit of commerce. Denatured alcohol is alcohol which, while fit for industrial uses, has been rendered unfit for drinking. This is accomplished by the addition of sub- stances, such as methyl alcohol and pyridine or benzine. Analytical Characters (1) Heated with a small quantity of solution of potassium dichromate and H 2 S0 4 , the liquid assumes an emerald-green color, and, if the quantity of C 2 H 6 is 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 HN0 3 is added to a liquid containing C 2 H 6 0, nitrous ether, recognizable by its odor, is given off. If a solution of mercurous nitrate with excess of HN0 3 is then added, and the mixture heated, a further evolution of nitrous ether occurs, and a yellow-gray deposit of fulminating mercury is formed, which may be collected, washed, dried, and exploded. (4) If an alcoholic liquid is heated for a few moments with H 2 S0 4 diluted with H 2 and distilled, the distillate, on treatment with H 2 S0 4 and potassium permanganate, and afterward with sodium thiosulphate, yields aldehyde, which may be recognized by the production of a vio- let color with a dilute solution of fuchsin. None of the above reactions, taken singly, is characteristic of alcohol. Alcohol is determined quantitatively in simple mixtures of alcohol and water by determining the specific gravity and referring to tables constructed for the purpose. In alcoholic beverages 100 cc. of the sample is distilled until 75 cc. have passed over ; the distillate is then made up to 100 cc. with water, and the sp. gr. determined. Alcoholic Beverages. These may be divided into four classes: 1. 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. Beer, ale and porter are aqueous infusions or decoctions of malted grain, fermented and flavored with hops. They contain all of the soluble constituents of the grain and hops, plus dextrins, maltose, glucose, alcohol and carbon dioxide. Their alcoholic contents varies from 1.5 to 9 per cent, absolute alcohol by weight. They contain a considerable proportion of nitrogenous material (0.4 to 1 per cent. N), and succinic, lactic and acetic acids. The most serious adulterations of malt liquors consist in the use of artificial glucose to furnish a part of the alcohol, and in the use of strychnine, picrotoxin, picric acid, or other bitter principles as substitutes for hops. Wine is fermented grape-juice. The expressed juice, called the must, con- tains much glucose, the fermentation of which is set up by yeast-plants growing upon the ^rape-skins. In red \\ines Hie color is produced by solution of the ALCOHOLS 219 coloring' matter of the skins in the accumulating alcohol. The same agency causes the precipitation of a part of the hydropotassic tartrate, to which the grape or wine owes its tartness. Sweet wines are made from grapes rich in glucose, and by arresting the fermentation before the sugar has been com- pletely decomposed. "Dry" or "brut" wines, which are not sweet, are fermented to completion. "Light" wines are such as contain less than 12 per cent, of alcohol, although they sometimes contain as much as 16 per cent. They are the products of temperate climates, and include the clarets, Sauternes, Bur- gundies, the Rhine, Moselle, Australian, Greek and Hungarian wines, and the wines of the northern portions of Spain, Italy and the United States. The champagnes also belong to this class, and are sparkling from the escape of carbon dioxide, produced by a secondary fermentation in the bottles, and held in solution by its own pressure. "Heavy" wines are those whose alcoholic strength is greater than 12 per cent., usually 14 to 25 per cent. They are the products of warm climates, and include the sherries of the south of Spain, the ports of Portugal, the Marsalas of the south of Italy, the Madeiras, and the wines of southern California. The adulteration of real wine is practically limited to the addition of coloring matters, and to " fortification " by the addi- tion of alcohol or brandy. Liquids are also manufactured to imitate wines, which contain no grape-juice. Cider is the fermented juice of the apple, and contains from 3.5 to 7.5 per cent, of alcohol. Spirits are prepared by fermentation and distillation. They differ from beers and wines in containing a larger percentage of alcohol, 35 to 50 per cent., and in not containing any of the non-volatile constituents of the grains or fruits from which they are prepared. They are yellow in color when stored in white oak casks the interior of which has been burnt, and colorless or faintly yellow when kept in unburnt casks. Besides alcohol and water they contain acetic, butyric, valeric and cenanthic esters, to which they owe their flavor. They include: brandy, sp. gr. 0.929-0.934, made by distilling wine; rum, sp. gr. 0.914-0.926, made by distilling molasses; and whiskies and gins, made by fer- menting and distilling grains, wheat, rye, barley or maize. The peculiar flavor of Scotch and Irish whiskies is derived from the smoke of a peat fire; that of gin is produced by distilling from juniper berries. In making straight whisky the distillate is not completely defuselated (p. 220), and by slow oxidation the remaining fusel produces the esters to which the spirit owes its flavor. Hence when newly made it is neither palatable nor wholesome, but in about three years in wood the fusel has been in great part removed by oxidation, the whisky is ripe, and continues to improve with age. In making blend whisky the distillate is completely defuselated to neutral spirit, and the product is made to imitate aged whisky more or less closely by addition of esters, " bead- ing oil " and other chemicals. Liqueurs or cordials are spirits sweetened and flavored with vegetable aromatics, and frequently colored; anisette is flavored with aniseed; absinthe, with wormwood ;curaQoa, with orange peel; kirschwasser, with cherries, the stones being cracked and the spirits distilled from the bruised fermented fruit; kiimmel, with cummin and caraway seeds; maraschino, with cherries; noyau, with peach and apricot kernels. Propyl Hydroxide Ethyl carbinol Primary propyl alcohol CH 3 .- CH 2 .CH 2 OH 60 is produced, along with ethylic alcohol, during fermentation, and obtained by fractional distillation of marc brandy, from cognac oil, huile de marc (not to be confounded with oil of wine), an oily matter, possessing the flavor of inferior brandy, which separates from marc brandy, distilled at high temperatures; and from the residues of manufacture of alcohol from beet-root, grain, molasses, etc. It is a colorless liquid, has a hot alcoholic taste, and a fruity odor; boils at 96.7; and is miscible with water. It has not been put 220 TEXT-BOOK OP CHEMISTRY to any use in the arts. Its intoxicating and poisonous actions are greater than those of ethyl alcohol. It exists in small quantity in cider. Butyl Alcohols C 4 H 9 OH 74. The four butyl alcohols theoretically pos- sible are known to exist: Propyl Carbinol Primary normal butyl alcohol Hutyl alcohol of fer- mentation CH 3 .CH 2 .CH 2 .CH 2 OH is formed in small quantities during alcoholic fermentation, and may be obtained by repeated fractional distillation from the oily liquid left in the rectification of vinic alcohol. It is a colorless liquid; boils at 116.8. It is more actively poisonous than ethyl or methyl alcohol. C'TJ V Isopropyl Carbinol Isobutyl alcohol r ,Tr 3 /CH.CH 2 OH occurs in the V^1 3 / fusel oil obtained in the products of fermentation and distillation of beet-root molasses. It is a colorless liquid, sp. gr. 0.8032; boils at 108.4. Ethyl-methyl Carbinol Secondary butyl alcohol CH 3 CH 2 \ pTTOTT CH 3 / C a liquid which boils at 99. CH 3 \ Trimethyl Carbinol Tertiary butyl alcohol, CH 3 COH a crystalline CH 3 / solid which fuses at 25, and boils at 82. Amy lie Alcohols C 5 H n OH 88. The eight amyl alcohols theo- retically possible (see p. 212) are known. The substance usually known as amylic alcohol, potato spirit, fusel oil, is the primary alcohol, 3 J>CH.CH 2 .CH 2 OH, with lesser quantities of other alco- hols, differing in nature and amount with the grain used, and the conditions of the fermentation and distillation, each kind of "spirit" furnishing and containing a peculiar fusel. In the process of manufacture of ardent spirits the fusel oil accumulates in great part in the still, but much of it distils over, and is more or less completely removed from the product by the process of defuselation. The individual amylic alcohols have the following characters: Butyl carbinol; normal amylic alcohol, CH,.CH,.CH a .CH 2 .CH 2 OH is a colorless liquid, boils at 137. Obtained from normal butyl alcohol, or from normal amylamine. It yields normal valeric acid on oxidation. Isobutyl Carbinol Amyl alcohol H5 a ^OH.CH 2 .OH,()H is the princi- V^-LAg / pal constituent of the fusel oil from grain and potatoes. It i> obtained from the last milky products of rectification of alcoholic liquids. These are shaken with H 2 to remove ethyl alcohol, the supernatant oily fluid is decanted, dried by contact with fused calcium chloride, and distilled; that portion which passes over between 128 and 132 being collected. It is a colorless, oily liquid, has an acrid taste and a peculiar odor, at first not unpleasant, afterward nauseating and provocative of severe headache. It boils at 131.4, and crystallizes at 20; sp. gr. 0.8184 at 15. It mixes with alcohol and ether, but not with water. It burns with a pale blue flame when sufficiently heated. When exposed to air it oxidizes very slowly; quite rapidly, however, in contact with platinum-black, forming isovaleric acid. The same acid, along with other substances, is produced by the action of the more powerful oxidants upon amyl alcohol. Chlorine attacks it energetically, forming amyl chloride, C,H lt CI, and other chlorinated derivatives. Sulphuric acid dissolves in amyl ALCOHOLS 221 alcohol, with formation of amyl-sulphuric acid, S0 4 (C B H U )H, corresponding to ethyl-sulphuric acid (p. 277). It also forms similar acids with phosphoric, oxalic, citric, and tartaric acids. Its esters, when dissolved in ethyl alcohol, have the taste and odor of various fruits, and are used in the preparation of artificial fruit-essences. Amyl alcohol is also used in analysis as a solvent, par- ticularly for certain alkaloids, and in pharmacy for the artificial production of valeric acid and the valerates. _ \ / Diethyl Carbinol ^ H 3 _ H 2 "/CHOH is produced by the action of a mix- ture of zinc and ethyl iodide on ethyl formate, with the subsequent addition of H 2 O. It is a liquid which boils at 116.5. OTT \ Methyl-propyl Carbinol CH _ CH _ ^ 3 ")CHOH a liquid, boiling at 118.5, obtained by the hydrogenation of methyl -propylic acetone. Methyl-isopropyl Carbinol , CH , _ ^ 3 yCHOH obtained by the hydro- genation of methyl-isopropylic acetone; or by the action of hydriodic acid upon amylene, and the action of moist silver oxide upon the product so obtained. It is a colorless liquid, sp. gr. 0.829 at 0, having a pungent, ethereal odor; boils at 112.5, soluble in H 2 and in alcohol. Ethyl-dimethyl Carbinol Tertiary amylic alcohol Amylene hydrate CH 3 \ CH 3 CH 2 COH is a liquid which solidifies at 12, and boils at 102.5; CH 3 / formed by the action of zinc methyl upon propionyl chloride, or by decomposi- tion of tertiary sulphamylic acid by boiling H 2 0. The nitrite of this alcohol has been used as a substitute for amyl nitrite. DIATOMIC, OR DIHYDRIC ALCOHOLS; GLYCOLS. The paraffin glycols are derived from the paraffins by the substi- tution of two hydroxyls for two H atoms. They bear the same rela- tion to the monoatomic alcohols that the diacid bases bear to the monacid bases. They are diprimary, disecondary, primary-secondary, etc., according as they contain groups CH 2 OH ; CHOH, or COH. Their "Geneva" names are derived from those of the parent hydro- carbons by the substitution of the syllable "dial" for the terminal e; and they are distinguished as a, fi, y, d, etc., according as the hy- droxyls occupy 1 :2,1 :3,1 :4,1 :5, etc., positions. Thus the primary- secondary glycol CH 2 OH.CH 2 .CHOH.CH 3 , is /?-butandiol. As the monohydric alcohols are regarded as the hydroxides of the univalent alkyls, so the dihydric alcohols are considered as the hy- droxides of bivalent hydrocarbon radicals: (CoH 4 )":(OH) 2 , which are called alkylenes. They may be obtained from the neutral haloid esters by heating with silver acetate : C 2 H 4 I 2 + 2AgC 2 H 3 2 =2AgI+C 2 H 4 ( C 2 H 3 2 ) 2 And saponification of the ester so formed by caustic potash : C 2 H 4 ( C 2 H 3 2 ) 2 -f 2KHO=C 2 H 4 ( OH) 2 +2KC 2 H 3 2 While the monoatomic alcohols are only capable of forming a sin- 222 TEXT-BOOK OF CHEMISTRY gle ester with a monobasic acid, the glycols are capable of forming two such esters: CH 2 ( C 2 H 3 2 ) ' CH 2 ( C 2 H 3 2 ) ' CH 2 ( C 2 H 3 2 ) ' CH 3 CH 2 OH CH 2 (C 2 H 3 2 )' Ethyl acetate. Moiioacetic glycol. Diacetic glycol. Ethene Glycol Ethylene glycol, or alcohol, or hydroxide CH 2 OH 62. This, the best known of the glycols, is prepared by the CH 2 OH action of dry silver acetate upon ethylene bromide. The ester so obtained is purified by redistillation, and decomposed by heating for some time with barium hydroxide. It is a colorless, slightly viscous liquid; odorless; faintly sweet; sp. gr. 1.125 at 0; boils at 197; sparingly soluble in ether; very soluble in water and in alcohol. It is not oxidized by simple exposure to air, but on contact with platinum-black it is oxidized to glycolic acid ; more energetic oxidants transform 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 CH 2 OH neutral compound ethene chlorhydrine, | , which boils at 130. Ditertiary glycols are produced by the action of organic mag- nesium halides upon the esters of dibasic acids in the same manner as tertiary monohydric alcohols are formed from those of monobasic acids (p. 213). Pinacone or tetramethylethylene glycol is a ditertiary alcohol produced by the action of nascent hydrogen (sodium) upon acetone: 2CH 3 .CO.CH 3 +H 2 = ( CH 3 ) 2 :COH.COH : ( CH 3 ) 2 It is also formed by the successive action of silver acetate and barium hydroxide on hexylene dibromide: ( CH 3 ) 2 .CBr.CBr : (CH.) 2 +2CH 3 .COO.Ag= (CH 3 ) 2 :C ( C 2 H 3 2 ) . C(C 2 H 3 2 ):(CH S ) 2 and (CH 3 ) 2 :C(C 2 H 3 2 ).(C 2 H 3 2 ).C:(CH 3 ) 2 +Ba(OH) 2 =(CH 3 ) 2 : COH.COH.(CH 3 ) 2 +Ba(C 2 H 3 2 ) 2 It is also produced by the general method, by the action of mag- nesium methiodide upon ethyl oxalate. TRIATOMIC, OR TRIHYDRIC ALCOHOLS; GLYCEROLS. These are derived from the paraffins by the substitution of three hydroxyls for three hydrogen atoms, linked to different carbon atoms. The simplest triprimary glycerol, which would have the formula: ALCOHOLS 223 CH(CH 2 OH) 3 , is unknown. The simplest known representative of the ^ class is the ordinary glycerine, more properly called glycerol, which is diprimary-secondary. The relations of the monoatomic, di- atomic, and triatomic alcohols to each other and to the parent hydro- carbon are shown in the following formulae: CH 8 CH 2 CH 3 CH 2 OH CH 2 OH CH 2 bH 2 CHOH CH 2 OH CH 2 OH CH 2 OH Propyl alcohol. Propyl glycol. Glycerol. Propane, The Geneva names of the glycerols are derived from those of the hydrocarbons by the substitution of the syllable "triol" for the ter- minal e. Thus glycerol is propantriol. They are obtained by the saponification of their esters, either those existing in nature or those produced artificially. They combine with acids to form three series of esters, known generically as monoglycerides, diglycerides, and triglycerides, formed by the combination of one molecule of the alcohol with one, two, or three molecules of a monobasic acid. The names of the in- dividual esters terminate in in, and have a prefix indicating the num- ber of acid residues. Thus: C 3 H 5 (OH) 2 .C 2 H 3 2 is monacetin, C 3 H 5 (OH) (C 2 H 3 2 ) 2 is diacetin, and C 3 H 5 (C 2 H 3 2 ) 3 is triacetin. Glycerol Glycerine Propenyl alcohol Glycerinum (U. S. P.) C 3 H 5 (OH) 3 92 was first obtained as a secondary product in the manufacture of lead plaster; it is now produced 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 quan- tity during alcoholic fermentation, and is consequently present in wine and beer. It is much more widely disseminated in its esters, the neutral fats, in the animal and vegetable kingdoms. It has been obtained by partial synthesis, by heating a mixture of allyl tribromide, silver acetate and acetic acid, and saponifying the triacetin so obtained. Also by total synthesis, by reduction of dioxy- acetone by sodium amalgam in presence of aluminium sulphate: CH 2 OH.CO.CH 2 OH+H 2 =CH 2 OH.CHOH.CH 2 OH Glycerol obtained by saponification of fats, and purified by dis- tillation in a current of superheated steam, known as " distilled gly- cerine, vy is reasonably pure. The only impurities likely to be present are water, and sometimes arsenic. Glycerol is a colorless, odorless, syrupy liquid, has a sweetish taste; sp. gr. 1.26 at 15. Although it cannot usually be caused to crystallize by the application of the most intense cold, it does so sometimes under imperfectly understood conditions, forming small, white needles of sp. gr. 1.268, and fusible between 17 and 18. 224 TEXT-BOOK OP CHEMISTRY It is soluble in all proportions in water and alcohol, insoluble in ether and in chloroform. It is a good solvent for a number of mineral and organic substances (glycerites and glyccroles). It is not volatile at ordinary temperatures. When impure glycerol is heated, a por- tion distils unaltered at 275-280, but the greater part is decom- posed into acrolein, acetic acid, carbon dioxide, and combustible gases. It may be distilled unchanged in a current of superheated steam be- tween 285 and 315. Pure glycerol distils unchanged at 290 at a pressure of 756 mm., and at 180 at 20 mm. Concentrated glycerol, when heated to 150 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. Glycerol is readily oxidized, yielding different products with dif- ferent degrees of oxidation. Platinum-black oxidizes it, with forma- tion, finally, of H 2 O and C0 2 . Oxidized by manganese dioxide and H 2 S0 4 , it yields C0 2 and formic acid. If a layer of glycerol diluted with an equal volume of H 2 is floated on the surface of HN0 3 of sp. gr. 1.5, a mixture of several acids is formed : oxalic, C 2 H 2 4 ; glyceric, C 3 H 6 4 , formic, CH 2 2 ; glycollic, C 2 H 4 3 ; glyoxylic, C 2 H 4 O 4 ; and tartaric, C 4 H (i O )5 . When glycerol is heated with potassium hydroxide, a mixture of potassium acetate and formate is produced. When glycerol, diluted with 20 volumes of H 2 0, is heated with Br; C0 2 , bromoform, glyceric acid, and HBr are produced. Phosphoric anhy- dride removes the elements of H 2 from glycerol, with formation of acrolein (p. 330). A similar action is effected by heating with H 2 S0 4 , or with monopotassic sulphate. Heated with oxalic acid, glycerol yields C0 2 and formic acid. The presence of glycerol in a liquid may be detected as follows : Add NaOH to feebly alkaline reaction, and dip into it a loop of Pt wire holding a borax bead ; then heat the bead in the blow-pipe flame, which is colored green if the liquid contain Moo of glycerol. The glycerol used for medicinal purposes should respond to the following 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 nitrate; (4) it should not be colored by H 2 S; (5) when dissolved in its own weight of alcohol, containing one per cent, of H 2 S0 4 , the solution should be clear; (6) when mixed with an equal volume H 2 S0 4 , of sp. gr. 1.83, it should form a limpid, brownish mixture, but should not give off gas. POLYATOMIC, OR POLYHYDRIC ALCOHOLS. Tetratomic Alcohols contain four hydroxyls. The best known is: Erythrol -Erythritc CH 2 OH. ( CHOH ) a .CH 2 OH which is a product of de- composition of erythrin, ('..,,H .,(),, which exists in the lichens of the ^enus rnrrlln. It crystiilli/cs in Inr^e, brilliant prisms; very soluble in H,<) and in hot alcohol, almost insoluble in ether; sweetish in taste; its solutions neither ALDEHYDES AND KETONES 225 affect polarized light, nor reduce Fehling's solution, nor are capable of fermen- tation. Its watery solution, like that of sugar, is capable of dissolving a con- siderable quantity of lime, and from this solution alcohol precipitates a definite compound of erythrite and calcium. By oxidation with platinum-black it yields erythroglucic acid, C 4 H 8 O 5 . With fuming HN0 3 it forms a tetranitro com- pound, which explodes under the hammer. Pentatomic, or Pentahydric Alcohols Pentites contain five hydroxyls. The only member of the group known to exist in nature is the simplest C 5 H 7 (OH) 5 , called adonite, obtained from Adonis vernalis. Other members of the series are obtained by reduction of the corresponding aldopentoses. Hexatomic, or Hexahydric Alcohols Hexites contain six hydroxyls. They are closely related to the sugars, which they resemble in their properties, although they do not reduce Fehling's solution, and are not fermented by yeast. They are obtained by reduction of the corresponding glucoses, aldo- hexoses and ketohexoses. Three hexites occur in nature: Mannitol Mannite CH 2 OH. ( CHOH ) 4 .CH 2 OH constitutes the greater part of manna, and also exists in a number of other plants. It is also produced during the so-called mucic fermentation of sugar, and during lactic fermenta- tion. It crystallizes in long prisms, odorless, sweet; fuses at 166 and crystal- lizes on cooling; boils at 200, at which temperature it is converted into mannitan, C 6 Hi 2 O 5 ; soluble in H 2 O, very sparingly in alcohol. Sorbitol Sorbite occurs in mountain-ash berries. It forms crystals, soluble in water. Dulcitol Dulcite Melampyrite Dulcose Dulcin exists in melampyrum nemorosum. It forms colorless, transparent prisms, fuses at 182, is odorless, faintly sweet, neutral in reaction, and optically inactive. It is subject to de- compositions very similar to those to which mannite is subject, yielding dulcitan, C 6 H 12 O 5 . Heptatomic, Octatomic and Nonatomic Alcohols, containing respectively seven, eight and nine hydroxyls, are also known. All polyatomic alcohols in solutions alkalized with caustic soda, when agitated with benzoyl chloride, form insoluble benzoic esters, and, under proper conditions, the separation is quantitative, a fact which is utilized for their separation. The diamines behave similarly with benzoyl Chloride. ALDEHYDES AND KETONES. The pure aldehydes and ketones, containing only CHO or CO and hydrocarbon groups, are to be considered rather as the second prod- ucts of oxidation of the paraffins than as the first products of oxi- dation of the alcohols, primary or secondary. While the distinction is not material with the aldehydes derivable from the monoatomic alcohols, it is so with similar derivatives of alcohols of higher atom- icity and with the ketones, which may be either pure aldehydes or ketones, or, if they retain alcoholic groups, substances of mixed function: aldehyde-alcohols and ketone-alcohols. Thus from the hydrocarbons the following may be derived : 2 ( CH 3 .CH 3 ) -j-O a =2 ( CH 3 .CH 2 OH ) Alcohols C M H 2n + 2 O, CH 3 .CH 3 -f0 2 =H 2 0+CH 3 .CHO Aldehydes C n H 2n O, CH 3 .CH 3 -f 20 2 =2H 2 0+CHO.CHO Glyoxals C w H 2r? _ 2 2 , CH 3 .CH 2 .CH 3 +0 2 =H 2 0+CH 3 .CO.CH 3 = Kc-tones C n H 2n O, and from the alcohols not only the above, but also substances such as 226 TEXT-BOOK OF CHEMISTRY 2 ( CH 2 OH.CH 2 OH ) -f0 2 =2H 2 O-|-2 ( CHO.CH 2 OH ) =Glycolyl aldehyde, 2 ( CH 2 OH.CHOH.CH 2 OH ) -f-O 2 =2H 2 O+2 ( CHO.CHOH.CH 2 OH ) =Glycerol aldehyde, 2 ( CH 2 OH.CHOH.CH 2 OH ) +O 2 =2H 2 0-f 2 ( CH 2 OH.CO.CH 2 OH ) =Glycerol ketone. The aldehydes and ketones are isomeric with each other and also with the alkyl alcohols, CH 2 :CH.CH 2 OH, and the methylene oxides, * Both aldehydes and ketones contain the carbonyl group CO, which in the ketone is united to two alkyls, CH 3 .CO.CH 3 ; and in the alde- hyde to one alkyl and a hydrogen atom, CH 3 .CO.H. Because of the presence of this oxygen atom, doubly linked to carbon, both aldehydes and ketones form addition products with hydrogen, the former to produce primary, and the latter secondary alcohols : CH 3 .CHO+H 2 =CH 3 .CH 2 OH, and CH 3 .CO.CH 3 +H 2 =CH 3 .CHOH.CH 3 . The aldehydes, in which the C:0: is in a terminal group, also form other addition products mentioned below. Aldehydes and ketones are acted upon by phosphorus penta- chloride to form compounds in which oxygen is replaced by the halogen. Thus acetic aldehyde yields ethidene chloride, or dichlor- ethane. CH 3 .CHO+PC1 5 =:CH 3 .CHC1 2 +POC1 3 And acetone yields ft dichlorpropane : CH 3 .CO.CH 3 +PC1 5 =CH 3 .CC1 2 .CH 3 +POC1 3 Aldehydes and ketones are acted upon by alkyl magnesium halides to produce secondary and tertiary alcohols (p. 290). All aldehydes and ketones condense with hydroxylamine to form oximes (p. 320) : CH 3 .CHO+NH 2 .OH=CH 3 .CH :N.OH+H 2 and with phenylhydrazine to form hydrazones and osazones (p. 380). Both of these reactions are extensively used for the identification of substances containing the C:0: group. The aldehydes and ketones may be considered as derivatives of formic aldehyde, :C(^, alkyls being substituted for one H atom only in the aldehydes: 0:C/^ H , and for both in the ketones: 0:C<^ ALDEHYDES. The name " aldehyde" is a contraction of "alcohol dehydrogen- atum," derived from the method of formation of these bodies by removal of hydrogen from alcohol. The aldehydes are formed: (1) By the limited oxidation of the corresponding alcohols: 2CH 3 .CH 2 OH+0 2 =2CH 3 .CHO+2H 2 ALDEHYDES AND KETONES 227 (2) 'By the action of nascent hydrogen upon the corresponding acidyl chlorides or anhydrides: CH 3 .CO.C1+H,=CH 3 .CHO+HC1, or (CH 3 .CO) 2 0+2H 2 =2CH 3 .CHO+H 2 (3) By the distillation of a mixture of calcium formate and the Ca salt of the corresponding acid: (H.COO) 2 Ca+ (CH 3 .COO) 2 Ca=2C0 3 Ca+2CH 3 .CHO (4) By the action of alkyl magnesium halides upon primary amides, and hydrolysis of the product. Thus propionic aldehyde is produced from acetamide : H 2 N.CO.CH 3 +CH 3 .Mg.Br.=H 2 N.CH,.CH(CH 3 ).O.Mg.Br and H 2 N.CH 2 .CH(CH 3 ).O.Mg.Br.+H 2 0=NH 3 +CH 3 .CH 2 CHO+ HO.Mg.Br. With formamide secondary reactions occur, but with its bisub- stituted derivatives, R 2 N.CHO, the formation of aldehydes proceeds normally. The aldehydes, being intermediate between the alcohols and acids, are readily converted into the former by the action of reducing agents : CH 3 .CHO+H 2 =CH 3 .CH 2 OH Or into the latter by oxidation: 2CH 3 .CHO+0 2 =2CH 3 .COOH The facility with which the aldehydes are oxidized renders them active reducing agents. They combine with the monometallic alkaline sulphites to form crystalline compounds, whose formation is frequently resorted to for their separation and purification: CH 3 .CHO+S0 3 HNa=CH 3 .CH(^ Na They unite directly with ammonia to produce crystalline com- pounds called aldehyde ammonias (p. 319) : CH 3 .CHO+NH 3 =CH 3 CH Chlorine and bromine displace the hydrogen of the aldehydic group with formation of acidyl chlorides or bromides: CH 3 .CHO+C1 2 =CH 3 .CO.C1+HC1 The oxygen of the same group may be displaced by chlorine, by the action of phosphorus pentachloride, with formation of paraffin dichlorides : CH 3 .CHO+PC1 5 =CH 3 .CHC1 2 +POC1 3 By indirect means compounds may be also obtained in which the hydrogen of the hydrocarbon group is substituted by chlorine, as chloral is obtained from ethylic alcohol : 228 TEXT-BOOK OF CHEMISTRY CH 8 .CH 2 OH+4C1 2 =CC1 3 .CHO+5HC1 The aldehydes polymerize readily, forming cyclic compounds, as trioxymethylene is formed by formic aldehyde: Or two aldehyde molecules may condense, by union through car- bon atoms, to form oxyaldehydes, as aldol is formed by condensa- tion of acetic aldehyde: 2CH 3 .CHO=CH 3 .CHOH.CH 2 .CHO Hydrocyanic acid combines with the aldehydes (and ketones) to produce oxycyanides, or nitriles of the oxyacids : which, in turn, are decomposable by acids or alkalies with forma- tion of the ^-oxyacids. Methanal Formaldehyde H.CHO 30 is formed when air charged with vapor of methylic alcohol is passed over an incan- descent platinum wire. It is also produced by the dry distillation of calcium formate: (H.COO) 2 Ca=CaC0 3 +H.COH By strong cooling, it condenses to a colorless liquid, which boils at 21 . It has a sharp, penetrating odor, and is an active germi- cide. It is extensively used as an antiseptic and disinfectant, either in the gaseous form or in aqueous solution. The commercial forma- line is a 40 per cent, solution. Formic aldehyde is probably produced as an intermediate product in plant nutrition, when carbon dioxide is decomposed by the green pigment, chlorophyll, under the influence of sunlight, with liberation of oxygen: C0 2 H-H 2 0=II.CHO+0 2 , and when so produced it may readily polymerize to form hexoses (p. 237) : 6H.CHO=C 6 H 12 . Formaldehyde polymerizes with great readiness by moderate eleva- tion of temperature to form paraformaldehyde, or trioxymethylene, \CH 8 'o/ CH which is also obtained as a crystalline substance, fusing' at 152, insoluble in H 2 0, alcohol and ether, by distilling glycollic acid with H 2 S0 4 , or by the action of silver oxalate or oxide on methene iodide: CH 2 I 2 +Ag 2 0=H.CHO+2AgL Formic aldehyde reacts with a great variety of substances, and. in reactions at elevated temperatures may advantageously be replaced by the solid trioxymethylene, which is then dissociated. Like all alde- hydes (and it is doubly an aldehyde: :Ct in three isomerides, differing from each other in their action upon polarized light. One of these rotates the plane of polarization to the right, and is designated as the dextro-, or d-com- pound; another is laevogyrous and is designated as the laevo-, or 1-compound, while the third is inactive, and is distinguished by the symbol (d- Stereoisomcrism, or Space Isomerism. The graphic formula indicate the structure of the molecule only partially; they .show that certain atoms in the molecule are attached to some of their fellows more closely than to others, but they give no indication of the positions which the atoms occupy in space H\ with regard to each other. The expression C O H, the most completely detailed graphic representation of that group, indicates at the most that the two hydrogen atoms are attached to one side of the carbon atom, while the hydroxyl is attached to another. Stereochemistry is that branch of cheni treating of the relations of the atoms to each other in space. It has been greatly developed in recent years and affords, among other things, the first rational explanation of the cause of the differences in the optical activity of the hexoses, as well as of lactic and tartaric acids, and of many other substances. If we suppose that differences in the relative positions which atoms or groups attached to carbon atoms occupy with relation to each other produce different compounds (see Place Isomerism, p. 260, Orientation, p. 337); and if we also suppose that the four valences of the carbon atom act in a plane and at right angles to each other, a vast number of space-isomerides of the di- and poly-substituted derivatives of the aliphatic hydrocarbons would exist, no rep- resentatives of which are, however, known. For example, marsh-gas would yield two isomerides of each of the types: CH 2 X,, CH 2 XY and CH X \. and three isomerides of the type CHXYZ, in which X, Y, and Z represent any three univalent atoms or radicals, thus: H H H H H H Cl (! Cl, Cl C H, Br C Cl, H C Cl, Cl C Cl, Cl C Br; d 1 i B, c, Type CH,X, Type CH,XY. Tjpe CHX,Y. H H H Cl C I, I C Br, and Br C Cl i CHXYZ. d, CARBOHYDRATES 239 8 Bu only one representative of each of these types is known. Therefore the usual graphic representation of the valences of the carbon atom as above, white convenient, is not spatially consistent with fact, and the four valences of the carbon atom are not exerted in one plane. The suggestion of Van't Hoff (following the somewhat similar idea of Kekule") that the valences of the carbon atom are represented by considering it as occupying the interior of a regular tetrahedron, the solid angles of which indicate the direction of its valences (Fig. 18, A), taken in connection with the hypothesis of an asymmetric carbon atom, affords a rational explanation of the facts just cited, and of the differences in the optical proper- ties of the substances mentioned. Admitting the regular tetra- hedron to represent the arrange- ment of the valences of the carbon atom, it follows that all carbon atoms, two of whose valences are satisfied by the same kind of uni- valent atom or group, and the other two by two constant but dissimilar univalents, must be symmetrical. The two similar univalents must occupy the sum- mits at the extremities of some one crest, and the only possible variation in arrangement of the other two is in their position with regard to this crest. Thus B and C, Fig. 18, although dissimilar in the position in which they are placed, become perfectly sym- metrical when either one is ro- tated through 180 degrees. But when all four of the carbon valences are satisfied by different univalents two arrangements are possible, producing two molecular groups which are unsymmetrical in whatever position they may be placed. Thus D and E, Fig. 18, are unsymmetrical in the positions in which they are represented, and remain so. however their positions may be changed. A carbon atom attached to four different uni- valents is called an asymmetric carbon atom. In graphic formulae asymmetric carbon atoms are designated by the italic C, or by an asterisk, C*. Substances containing an asymmetric carbon atom exist in three optical isomeres: dextrogyrous (d), la'royi/rons (1), and optically inactive, or racemic (d-fl or i, or r). The structure of the four isomerie tartaric acids was first explained under the hypothesis of the asymmetric carbon atom. Let it be assumed that two asymmetric carbon atoms, with their attached groups or atoms, exert a "di- recting influence" upon each other, and that, being attached to each other at one point only, they are capable of rotating independently about a common axis (a. a. Fig. 18, G), such rotation would then occur in obedience to the gucH.on, 240 TEXT-BOOK OF CHEMISTRY directing influence until a condition of equilibrium is reached, in which position the atoms would remain. Assuming this position to be that shown in F, G, and H, Fig. 18, with the two COOH groups in like relation, then the three unsymmetrical arrangements shown in the figure arc possible. The lirst rep- resents the structure of dextro-tartaric acid, G that of laevo-tartaric acid, and H that of meso-tartaric acid, while racemic acid is a combination of dextro- and laevo-tartaric acids. The tetrahedron representation of the carbon valences adapts itself well also to the explanation of certain isomerides of the ethylene series, in which two carbon atoms are doubly linked together. In these Hie two carbon atoms being linked together at two points (I and K, Fig. 18) cannot be considered as being capable of rotation, and, if tbe two other valences of each carbon are satisfied by the same two dissimilar univalents, two positions are possible: I, in which the like univalents are directed to the same side, called the "plane symmetrical configuration," and K, in which they are directed towards opposite sides, called the " axially symmetrical configuration." Formose is a synthetic hexose, obtained by polymerization of formic aldehyde : 6H.CHO=CeH 12 O Acrose is similarly obtained from glyceric aldehyde: 2CH,OH.CHOH.CHO=C 6 H 12 O 6 or by the action of barium hydroxide upon acrolein bromide: 2CH 2 Br.CHBr.CHO+2Ba ( OH ) 2 =C 6 H 12 O 6 + 2BaBr 2 Mannose is obtained, as d-, 1-, and d+1, mannoses by oxidation of the cor- responding mannitols. Glucose Grape Sugar Dextrose Liver Sugar Diabetic Sugar d-Glucose occurs in many sweet fruits and vegetable juices, and in honey, accompanied by fructose ; and, in the animal world, in the contents of the intestine, liver, bile, thymus, heart, lungs, blood, and, in small quantity, in the urine. Pathologically, it appears in the saliva, perspiration, feces, and, in largely increased amount, in the blood and urine in diabetes mellitus. It is produced by the decom- position of the polysaccharides and of many of the glucosides, and is manufactured on a large scale by the action of boiling dilute H 2 S0 4 upon starch. The commercial product so obtained is either an amor- phous, white solid (grape sugar), containing about 60% of true glu- cose, along with dextrins and the unfermentable isomaltose, or gallisin, C 12 H 22 O n ; or a thick, colorless syrup (glucose), containing, besides the above, a minute quantity of a nitrogenous body which exerts a solvent action upon coagulated albumin at the body tem- perature. d-Glucose has been produced synthetically by the reduction of the lactone of d-gluconic acid. It crystallizes from its aqueous solutions at the ordinary tempera- ture with difficulty in white, opaque, spheroidal masses containing 1A<|. which fuse at 86 and lose the Aq at 110. From its concen- trated aqueous solution at 30 to 35, or from its alcoholic solution it crystallizes in hard, anhydrous, crystalline crusts, which fuse at 146. CARBOHYDRATES 241 It is soluble in all proportions in hot water, is very soluble in cold water, and soluble in alcohol. It is less sweet and less soluble than cane sugar. Its aqueous solutions are dextrogyrous : [a] D =:-j-52.6 in boiled solutions. Freshly prepared cold aqueous solutions have nearly double that rotary power at first, the value of [a] D gradually falling to 52.6 in about twenty-four hours. Its osazone, d-.glucosa- zone, crystallizes in needles, fusible at 205. Its solutions dissolve baryta and lime, with which, as with potash, soda, and the oxides of Pb and Cu, it forms saccharates. l-Glucose is formed by reduction of the lactone of 1-gluconic acid. It is in all respects similar to d-glucose except that it fuses at 143, and its solutions are laevogyrous [rt] D = 51.4. d+l-Glucose is formed by reduction of d+1-gluconic lactone; or by union of d- and 1-glucose. Its solutions are optically inactive. Galactose is also known in its three modifications. d-Galactose is pro- duced by the hydrolysis of milk sugar and of certain gums. It crystallizes more readily than glucose, is very sparingly soluble in cold alcohol, has a specific rotary power of [a} D =-(-83.33, and fuses at 160. By reduction it yields dulcite, and by oxidation galactonic acid, CH 2 OH. (CHOH) 4 .COOH, and mucic acid, COOH.(CHOH) 4 .COOH. Cerebrose, obtained by the hydrolysis of cerebrin, a constituent of nerve tissue, is identical with galactose. Fructose Levulose a ketohexose, exists in the three modifications. d-Fructose Fruit sugar forms the uncrystallizable portion of the sugar of fruits and of honey, in which it is associated with glucose; it is produced artificially by the prolonged action of boiling water upon inulin, a polysac- charide; also, along with an equal quantity of glucose, as one of the constitu- ents of invert sugar, by the decomposition of cane sugar; and from d-glucosa- zone. It crystallizes with great difficulty, fuses at 05, is very soluble in water, and insoluble in absolute alcohol. Although called d-fructose, because of its formation from d-glucosazone, it is strongly loevorotary: [a] D =: 71.4. It is less readily fermentable than glucose, which it equals in the readiness with which it reduces cupropotassic solutions. With phenylhydrazine it yields d-glucosazone (p. 381). Sorbinose, also a ketohexose, occurs in the berries of the mountain ash. It does not ferment. Its osazone fuses at 164. DISACCHARIDES SACCHAROBIOSES. Disaccharides consist of two molecules of monosaccharides, united with elimination of H 2 0. So far as is known they are all derived from the hexoses, and their formula is consequently C^H^On. They are all capable of yielding two hexose molecules by hydrolysis: C 1I H M U +H,0=2C.H 11 0. a change which is called "inversion." The union of the two monosaccharide molecules is either through the aldehyde, ketone, or alcoholic groups. Of the three most important disaccharides, sac- charose, lactose and maltose, the first named has no reducing power, and yields no osazone with phenylhydrazine. It therefore contains 242 TEXT-BOOK OF CHEMISTRY no aldehyde or ketone group. When heated with acetic anhydride to 160 it forms an octacetyl ester, C 12 H 14 3 (O.C 2 H 3 0) 8 . It there- fore contains eight hydroxyls. When hydrolyzed it yields d-glucose and d-fructose (laevogyratory). From the above facts we may infer that saccharose is derived from the two hexoses named, united through the aldehyde and ketone groups, a constitution which may be represented by the f ormulae : CH 2 OH.CO. ( CHOH ) 2 .CHOH.CH 2 OH CHO. ( CHOH ) 4 .CH 2 OH d-Fructose. d-Glucose. OX /O CH 2 OH.CH. ( CHOH ) 2 .C.CH 2 OH. CH. ( CHOH ) 4 .CH 2 Saccharose. Lactose and maltose both cause reduction and yield osazones. On hydrolysis the former yields d-glucose and galactose, and the latter only d-glucose. They each consequently retain an aldehyde (or ketone) group, and their constitution may probably be represented thus: ,0 CH 2 OH.CHOH.CH. ( CHOH ) 2 .CH.O.CH 2 . ( CHOH ) 4 .CHO and /0\ CHO. ( CHOH ) 4 .CH 2 CH a .(CHOH) 4 .CHO The disaccharides are hydrolyzed by boiling with very dilute acids, or even with water, and by several enzymes such as diastase, emulsin, invertin, ptyalin, trypsin and pepsin. Saccharose Cane Sugar 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 saccharinum. For the extraction of sugar the expressed juice is heated in large pans to about 100; milk of lime is added, which causes the precipitation of albumin, wax, calcic phosphate, etc. ; the clear liquid is drawn off, and " delimed " by passing a current of CO 2 through it; the clear liquid is again drawn off and evaporated, during agitation, to the crystallizing point; the product is drained, leaving what is termed raw or muscovado sugar, while the liquor which drains off is molasses. The sugar so obtained is purified by the process of "refining," which consists essentially in adding to the raw sugar, in solution, albumin in some form, which is then coagulated; filtering first through canvas, afterward through animal charcoal ; and evaporating the clear liquid in " vacuum-pans," at a temperature not exceeding 72, to the crystallizing point. The product is allowed to crystallize in earthen moulds; a saturated solution of pure sugar i- poured upon the crystalline mass in order to displace the nncrystallfzable sugar which still remains, and the loaf is finally dried in an oven. The liquid dis- placed as above is what is known as sugar-house syrup. Pure sugar should bo entirely soluble in water; the solution should not turn brown when warmed with dilute potassium hydroxide solu- CARBOHYDRATES 243 tion; should not reduce Fehling's solution, and should give no pre- cipitate with ammonium 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, without agi- tation. Maple-sugar is a partially refined, but not decolorized variety 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 addition of alcohol. Aqueous solutions of cane- sugar are dextrogyrous, [a] D =-j-66.5. When saccharose is heated to 160 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 glucose and Isevulosan ; at a still higher temperature, H 2 O is given off, and the glucose already formed is converted into glucosan; at about 200 the evolution of H 2 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 H 2 O, or in aqueous alcohol, and used to communicate color to spirits; finally, at higher tempera- tures, 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 If saccharose is boiled for some time with H 2 0, it is converted into inverted sugar, which is a mixture of glucose and fructose: C 12 H 22 11 +H 2 0=C a H 12 6 +C 6 H 12 6 With a solution of saccharose the polarization is dextrogyrous, but, after inversion, it becomes lasvogyrous, because the left-handed action of the molecule of fructose produced, [a]D= 71.4, is only partly neutralized by the right-handed action of the glucose, [a]u=+52.6 . This inversion of cane sugar is utilized in the test- ing of samples of sugar. On the other hand, it is to avoid its occur- rence, and the consequent loss of sugar, that the vacuum-pan is used in refining its object being to remove the H 2 at a low temperature. With potassium chlorate, sugar forms a mixture which detonates when subjected to shock, and which deflagrates when moistened with H 2 S0 4 . Concentrated H 2 S0 4 blackens it. Dilute HN0 3 , when heated with saccharose, oxidizes it to saccharic and oxalic acids. 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 sue- 244 TEXT-BOOK OF CHEMISTRY rates (improperly saccharates, a name belonging to the salts of sac- charic acid). With Ca it forms five compounds. Calcium hydroxide dissolves readily in solutions of sugar, with formation of a Ca com- pound, soluble in H 2 0, containing an excess of sugar. During the process of digestion, probably in the small intestine, cane-sugar is inverted. Lactose Milk Sugar Saccharum lactis (U. S. P.) occurs in the milk of the mammalia, in the amniotic fluid of cows, and in the urine of women towards the end of gestation and during lactation. It may be obtained from skim-milk by coagulating the casein with a small quantity of H 2 S0 4 , filtering, evaporating, redissolving, de- colorizing with animal charcoal, and recrystallizing. It forms prismatic crystals ; sp. gr. 1.53 ; hard, transparent, faintly sweet, soluble in 6 parts of cold and 2.5 parts of boiling H 2 ; soluble in acetic acid ; insoluble in alcohol and in ether. Its solutions are dextrogyrous [a] D =-(-52.5. The crystals, dried at 100, contain lAq, which they lose at 150. Lactose is not altered by contact with air. Heated with dilute mineral acids or with strong organic acids, it is converted into galac- tose. HN0 3 oxidizes it to mucic and oxalic acids. A mixture of HN0 3 and H 2 S0 4 converts it into an explosive nitro-compound. With organic acids it forms esters. With soda, potash and lime it forms compounds similar to those of saccharose, from which lactose may be recovered by neutralization, unless they have been heated to 100, at which temperature they are decomposed. It reduces Fehl- ing's solution, and reacts with Trommer's test. Its osazone fuses at 200. In the presence of yeast, lactose is capable of alcoholic fermenta- tion, which takes place slowly, and, as it appears, without previous transformation of the lactose into glucose and galactose. On contact with putrefying proteins it enters into lactic fermentation. It is converted into galactose by the pancreatic secretion. Maltose is formed, along with dextrins, during the conversion of starch, or of glycogen, into sugar by the action of diastase (in malting grain), and of the enzymes of the saliva and the pancreatic juice. It is also an intermediate product in the hydrolysis of starch by dilute sulphuric acid. Maltose crystallizes in hard, white needles aggregated into crusts. It is less soluble in alcohol than is glucose, and has a much higher dextrogyratory power [a] D =+137. It re- duces Fehling's solution. It is hydmlyzed by boiling with dilute acids, yielding only d-glucose. It is fermentable. Its osazone fuses at 206. Nitric acid oxidizes it to d-saccharic acid. Isomaltose Gallisin is formed along with maltose, in the action of diastase, saliva, or pancreatic juice, or of boiling dilute acids, on starch, and exists in beer and artificial glucose. It is also formed by the prolonged action of strong 1IC1 on d-glucose. It is very soluble in water, very sweet, CARBOHYDRATES 245 and does not ferment, or does so very slowly. Its osazone forms yellow needles, which fuse at 150, and are rather soluble in hot water. TRISACCHARIDES. Several members of this group have been obtained from different vegetables. They have the formula C 18 H 32 16 . The best known are Raffinose, or Melitose, which occurs in eucalyptus-manna, in cotton seed, and in beet-sugar molasses; and Melecitose, from the manna of Pinus larix. POLYSACCHARIDES. The starches, gums, and celluloses, which form this class, have the empirical formula C 6 H 10 5 , but their molecular weights are much greater than that represented by that formula. They are very widely distributed in vegetable nature. On hydrolysis they are finally de- composed to monosaccharides, for the most part hexoses, although some of the gums yield pentoses. Starch Amylum the most important member of the group, ex- ists in the roots, stems, and seeds of all plants ; and is obtained com- mercially from rice, potatoes, and maize. It is a white powder, con- sisting of granules which are round, ovoid or irregular in outline, and, in some cases, marked with a central spot or line) called the hilum, and with concentric rings. Differences in the shape, size and markings of the granules are utilized to identify the vegetable from which the starch was obtained. Air-dried starch contains 18% of water, of which it loses 8% in vacuo, and the remainder only at 145. Starch is insoluble in cold water and in alcohol. If 15 to 20 parts of H 2 are gradually heated with one part of starch, the granules swell at about 55, and at 80 they have lost their structure, have swelled to thirty times their original volume, and have formed a homogeneous, translucent, gelatinous mass, commonly known as starch paste. This hydrated starch consists of an insoluble portion, starch cellulose, and a soluble portion, granulose, or soluble starch. Granulose forms an opalescent solution in water, from which it is precipitated as a white powder by alcohol. Its solutions are strongly dextrogyrous, [aJD=+207 (about). By prolonged boiling with water, or, more rapidly, by boiling dilute mineral acids, or by the action of diastatic enzymes, soluble starch is converted into dextrins, maltose, and finally, d-glucose. Dry heat causes the starch granules to burst, with formation of dextrin. A dilute solution of iodine produces a violet-blue color with starch, whether dry, hydrated, or in solution. The color is discharged by heat, but reappears on cool- ing. Concentrated HN0 3 dissolves starch in the cold, forming a nitro-product, called xylodin, or pyroxam, which is insoluble in water, soluble in a mixture of alcohol and ether, and explosive. Glycogen Animal Starch occurs in the liver, the placenta, white blood corpuscles, pus cells, young cartilage cells, muscular tissue and many embryonic tissues, also in many molluscs. It is 246 TEXT-BOOK OF CHEMISTRY best obtained from liver tissue, by extraction with hot water and precipitation by alcohol, after separation of protein bodies by potas- sium iodhydrargyrate and acetic acid. It is a snow-white, floury powder, amorphous, tasteless, and colorless; soluble in water, forming an opalescent solution, insoluble in alcohol or ether. Its solutions are strongly dextrogyrous, [a] D =-f-196.6. Glycogen is converted into dextrins, maltose, and, ultimately, d-glucose by the action of boiling dilute acids, and by the salivary, pancreatic and hepatic diastatic enzymes. Glycogen is colored wine-red by iodine, the color being discharged by heat and returning on cooling. Its solutions dissolve, but do not reduce cupric hydroxide. Other starches are: Paramylum, occurring in certain infusoria; Lichenin, in lichens and mosses; and Inulin, in the roots of dahlia, chicory and other plants. Gums are amorphous, translucent substances occurring in many plants. They are insoluble in alcohol and in ether. With water some of them, the true gums, form clear solutions ; while others, the vege- table mucilages, swell up to sticky masses which cannot be filtered through paper. On boiling with dilute H 2 S0 4 the gums yield d-glucose, galactose, or 1-arabinose. Nitric acid oxidizes them to mucic, oxalic and saccharic acids. The commoner members of the group are : Arabin, the chief con- stituent of gum arabic (acacia) and gum Senegal; and Bassorin, the chief ingredient of gum tragacanth, Bassora gum, and plum and cherry gums. Dextrin British gum a substance resembling gum arabic in appearance and in many properties, is obtained by one of three methods: (1) by subjecting starch to a dry heat of 175; (2) by heating starch with dilute H 2 S0 4 to 90 until a drop of the liquid gives only a wine-red color with iodine; neutralizing with chalk, filtering, concentrating, precipitating 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 pow- der, soluble in H 2 in all proportions, forming mucilaginous liquids. When obtained by evaporation of its solution, it forms masse re- sembling gum arabic in appearance. 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 as a substitute for gum acacia. By the action of diastase upon starch, four dextrins are produced : (1) Erythrodextrin, which is colored red by iodine, and which is easily attacked by diastase; (2) Achroodextrin , not colored by iodine; partially converted into sugar by diastase; rotary power CARBOHYDRATES 247 [a] D =4-210; reducing power (glucose=ilOO)=:12 ; (3) Achroo- dextrin /?, not colored by iodine, nor decomposable in twenty-four hours by diastase; rotary power-f-190 ; reducing power=12; (4) Achroodextrin y , not colored by iodine, nor decomposed by diastase; slowly converted into glucose by dilute H 2 S0 4 ; rotary powers +150; reducing power=28. An explanation of this series of transformations has been sug- gested in the supposition that the molecule of starch consists of 50(C 12 H 20 10 ) ; that this is first converted into soluble starch 10(C 12 H 20 10 ) ; 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(C 12 H 20 10 ) + 8(H 2 0) = 2(C 12 H 20 10 ) + 8(C 1: E 22 U ) 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 KOH and afterwards with dilute HC1, yields pure cellulose (absorbent cotton). It is white, has the shape of the fiber from which it was derived, is insoluble in the usual solvents, but soluble in the dark blue liquid formed by dissolving copper in ammonia in contact with air. Vegetable parchment Parchment paper is obtained by dip- ping unsized paper for an instant in H 2 S0 4 , diluted with an equal volume of H 2 O, washing thoroughly, and drying. It is a tough ma- terial resembling animal parchment. Gun-cotton Pyroxylin Nitrocellulose is obtained by dipping pure cotton in a cold mixture of one part of HN0 3 and two-thirds of H 2 S0 4 for from three to ten minutes, washing thoroughly, and dry- ing. It consists of hexanitrocellulose, C 12 H 14 (O.N0 2 ) 6 4 , is violently explosive, and is insoluble in a mixture of alcohol and ether. Soluble pyroxylin is obtained by acting on cotton with a warm mixture of twenty parts of nitre and thirty parts of concentrated H 2 S0 4 , washing and drying. It consists of penta- and tetra-nitro- cellulose, is soluble in a mixture of alcohol and ether, and is used in the preparation of collodion. Explosive gelatin, or smokeless pow- der, is a desiccated mixture of nitro-glycerol and collodion. Celluloid is a mixture of gun-cotton and camphor, combined by pressure. Tests for Carbohydrates. A. Furfurole Reaction T aliens' Re- action for pentoses (not hexoses) depends upon the fact that these compounds yield furfurole by loss of water when they are heated with HC1. The reagent consists of 1 gm. phloroglucin, dis- solved in 500 cc. of 30 per cent. HC1, to which 30 drops of a 30 per 248 TEXT-BOOK OF CHEMISTRY cent, solution of FeCl 3 are added. About 5 cc. of the reagent are heated to boiling, and the liquid added. The formation of a cherry- red color indicates the presence of a pentose. Orcin may be substi- tuted for phloroglucin in the reagent, when the color produced is green. Orcin has the advantage over phloroglucin that the glucuron- ates do not react with the former, but do with the latter. B. Aldehyde and Ketone Reactions. These reactions depend upon the presence in the carbohydrates of the CHO or CO group, and are consequently given by cane-sugar, non-reducing dextrins and starch, which do not contain such groups, only after their hydrolysis by boiling with dilute acids; but are given by other substances con- taining ketone or aldehyde groups. 1. Copper Reduction Tests. These and other reduction tests are produced not only by aldoses and ketoses, but also by other reducing agents. Therefore, such substances, as well as albumin, must be excluded before these tests are resorted to. This may be accomplished by Focke's method, by boiling 10 cc. of liquid (urine) with 5 cc. of CuS0 4 solution (1:10), filtering, adding 2 cc. Na 2 C0 3 solution (1:10) to the cool filtrate, and filtering again after standing. Trommer's Reaction is the earliest form of reduction test for sugar. It consists in adding about one-eighth of NaOH or KOH solu- tion (1:10) to the dilute saccharine liquid, then two to three drops of CuS0 4 solution (1 :10) and heating the blue liquid just to boiling. A yellow ppt. is formed, which becomes darker and reddish on boiling. Feeling's Test. The reagent must be kept in two solutions, which are to be mixed immediately before use. If the reagent is made in a single solution it is prone to self-reduction. Solution I consists of 34.653 gms. of crystallized CuS0 4 , dissolved in water to 500 cc. ; and II, of 130 gms. of Rochelle salt dissolved to 500 cc. in NaOH solution of sp. gr. 1.12. When required for use equal volumes of the two solutions are mixed, and the mixture diluted with four volumes of water. A few cc. of this liquid are heated to boiling, and the saccha- rine liquid (urine) added in small portions, the contents of the test- tube being heated short of boiling, but not boiled, after each addition. A reducing sugar produces a yellow or red ppt., which forms more or less rapidly according to the amount of sugar present. The liquid should not be boiled after addition of urine, as creatinine and uric acid may reduce by boiling. Glucuronates and glycosurates also reduce. There are many modifications of this test, in which potassium tartrate, mannite, glycerol, etc., are used in place of Rochelle salt, but they present no advantages over the above. Pavy's solution is a modified Fehling, containing a notable amount of ammonia. It has the advantage for quantitative work that the blue color is more sharply discharged on total reduction, but it is open to the objection that the ppt. is soluble in the ammoniacal liquid. CARBOHYDRATES 249 2. Bismuth Reduction Tests. Boettger's test may be applied either in the manner originally indicated, or in Nylander's or Almen's modifications. Equal portions of the liquid are placed in two test tubes, to each of which enough solution of Na 2 C0 3 is added to make the reaction distinctly alkaline, and to one a little powdered bismuth subnitrate, and to the other a little powdered litharge are added. The contents of the two tubes are then heated to boiling, when, if the bismuth powder becomes black and the litharge remains unchanged, the presence of a reducing sugar may be inferred. The purpose of the litharge is to guard against error from the presence of sulphur compounds, which blacken both the bismuth and lead powders. Nylander's solution is made by adding 4 gms. of Rochelle salts, 2 gms. of bismuth subnitrate and 10 gms. of caustic soda to 90 cc. of water, boiling, cooling and filtering. To use the test 1 cc. of the reagent is added to the liquid and the mixture boiled, when a reducing sugar causes the formation of a gray or black ppt. A parallel testing with litharge is also required. An affirmative result is obtained with urine in the absence of sugar when large doses of quinine have been taken, but uric acid and creatinine do not react, and therefore this reaction is preferable to the copper reduction tests, although glucuro- nates react with it. 3. Osazone Reaction. The phenylhydrazine test, or Fischer's, or Riegler's test depends upon the formation of osazones by all mono- saccharides and disaccharides containing CO or CHO groups. To 10 cc. of the liquid (urine) in a test tube, add 0.5 gm. phenylhy- drazine hydrochloride and 1 gm. sodium acetate, and cause the pow- ders to dissolve by warming, and, if necessary, the addition of water, and leave the test tube in a boiling-water bath for one hour, after which cool it by immersion in cold water. If a ketose or aldose, whether hexose or pentose, or a glucuronate is present a yellow ppt. is formed, usually crystalline, which should be collected and examined microscopically. Needle-shaped crystals are formed by glucose, fruc- tose, maltose and glucuronic acid. The osazones of glucose and fruc- tose are one and the same substance. The several osazones have dif- ferent fusing points: that of glucuronic acid, 114-115; of isomal- tose, 150-153; of arabinose, 159; of galactose, 193; of glucose and fructose, 204-205, and of maltose, 206. To determine the fusing point the ppt. is collected, dissolved in hot alcohol, the solu- tion filtered and evaporated, the crystals dried over H 2 S0 4 , placed in a small closed tube attached to the bulb of a thermometer by a pasted slip of paper, and heated in a paraffin bath, the temperature being noted when the material fuses. Aldehydes and ketones also form hydrazones. 4. Fermentation Test. Three Smith's fermentation-tubes are used, one (A) completely filled with water, one (B) with a dilute solution of glucose, and the third (C) with the liquid (urine) to be 250 TEXT-BOOK OF CHEMISTRY tested, and each containing a little compressed yeast. The three tubes are put in warm place and left over-night, when if gas has collected in B and C and none in A the urine contains sugar ; if gas has collected in B, but none in A or C it is absent ; under any other circumstances the yeast is at fault. The only substances other than glucose which respond to this test are the other fermentable carbo- hydrates, lactose, maltose and fructose. CARBOXYLIC ACIDS. These compounds are the third products of oxidation of the CH 3 groups of the paraffins and contain the characterizing group of atoms 0:C.OH (carboxyl). They are either pure acids, containing only the carboxyl and hydrocarbon groups; or alcohol-acids, containing also the groups CH 2 OH, CHOH or COH ; or aldehyde-acids, contain- ing CHO ; or ketone-acids, containing CO ; or of still more complex function, containing two or more of the above groups. The most important of the pure acids are those of the acetic (CnH2n02), and oxalic (CnH2w-204) series, the former of which are monobasic, the latter dibasic. Other pure acids of higher basicity are also known in which the carboxyl groups are substituted for hydro- gen atoms in the hydrocarbon. PARAFFIN MONOCARBOXYLIC ACIDS VOLATILE FATTY ACIDS- ACETIC SERIESSERIES C n H 2n O 2 The lowest terms of the series are volatile liquids, the highest are solids and exist in their glycerol esters in the fats ; hence the name of volatile fatty acids. The solid acids, the tenth and higher of the series, cannot be distilled without decomposition except in super- heated steam. As the hydrocarbons may be considered as the hydrides of the alkyls, and the alcohols as their hydroxides, so the acids may be considered as the hydroxides of the acidyls: the acid or oxidized radicals. Thus acetic acid is acetyl hydroxide, (CH 3 .CO)OH. These acids may be obtained: (1) By oxidation of the corresponding alcohol or aldehyde: C 2 H 5 .CH 2 OH+0 2 =C 2 H 5 .COOH+H 2 0, or 2CH 3 .CHO+0 2 =2CH 3 .COOH (2) By decomposition of the dicarboxylic acids, with elimination of carbon dioxide: COOH.COOH=:H.COOH+CO,, and COOH.CH 2 .COOH=rCH 3 .COOH-fCO i; (3) By the action of carbon monoxide upon an alkaline hydroxide or alcoholate: CARBOXYLIC ACIDS 251 CO+NaOH=H.COONa, and CO+C 2 H 5 .O.Na=C 2 H 5 .COONa (4) From the nitriles, or hydrocyanic esters, by the action of acids or alkalies in the presence of water: HCN+H,0+KOH=H.COOK+NH 3 , or CH 3 .CN+2H 2 0+HC1=CH 3 .COOH+NH 4 C1 This constitutes a general method for the introduction of carboxyl, starting from the haloid derivatives of the hydrocarbon. This is converted into the cyanide, or nitrile by heating with alcoholic po- tassium cyanide: BrCH,.CH 3 +KCN=CNCH 2 .CH 3 -f-KBr, or BrCH 2 .CH 2 Br+2KCN=CN.CH 2 .CH 2 .CN+2KBr and the cyanide is then converted into the acid by elimination of the nitrogen as ammonia, and the substitution of OOH in its place by the action of acids or of alkalies: CN.CH 2 .CH 3 +HC1+2H 2 0=COOH.CH 2 CH 3 +NH 4 C1, or CN.CH 2 .CH 2 .CN+2KOH+2H 2 0=COOK.CH 2 .CH 2 .COOK+2NH 3 (5) By passing carbon dioxide through ethereal solutions of alkyl magnesium bromides or iodides and hydrolyzing the product: CH 3 .Mg.Br+C0 2 =CH 3 .COO.Mg.Br, and CH 3 .COO.Mg.Br+H 2 0=CH 3 .COOH+HO.Mg.Br. Methan Acid Formic Acid H.COOH. Although it is the first term of this series, formic acid differs from its superior homologues in several respects: (1) It is not a pure acid, but an aldehyde-acid, the single carbon atom forming part of both groups: 0:C<^^ ; (2) The halogens do not convert it into halide-formic (or carbonic) acids, but split it to carbon dioxide and the hydracid : H.COOH+C1 2 =C0 2 +2HC1 (3) By elimination of water it yields carbon monoxide: H.COOH=CO+H 2 (4) It produces no acidyl halide or anhydride corresponding to those of its superior homologues. It occurs in the bodies of ants and of other insects, and in the blood, bile, perspiration and muscular fluid of mammalia. It is pro- duced by oxidation of sugar, starch, gelatin, albumin, etc.; in the fermentation of diabetic urine; by the action of potash upon chloro- form: CHC1 3 +4KOH=H.COOK+3KC1+2H 2 By the action of hydrating agents upon its nitrile, hydrocyanic acid: HCN+2H 2 0=:H.COO(NH 4 ) 252 TEXT-BOOK OF CHEMISTRY And by decomposition of oxalic acid in the presence of glycerol at about 100: COOH.COOH=H.COOH+C0 2 It is a colorless liquid of acid taste and penetrating odor, b. p. 100, crystallizes at 0, miscible with water. It is decomposed by mineral acids to carbon monoxide and water : H.COOH:=CO-hH 2 ; by oxidizing agents to carbon dioxide and water: 2H.COOH-f-0 2 = 2H 2 0+2C0 2 ; and by caustic alkalies to a carbonate and hydrogen; H.COOH+KOH=KHC0 3 +H 2 . It reduces the salts of Au, Ag, and Hg. Orthoformic Acid, CH(OH) 3 , so called because of its analogy to tribasic or "ortho" phosphoric acid OP(OH) 3 is only known in its esters (p. 277). Ethan Acid Acetic Acid Acetyl Hydroxide Acidum aceticum (U. S. P.) CH 3 .COOH is formed by the general methods, and (1) by the action of carbon dioxide on sodium methyl: C0 2 -f-NaCH 3 = CHg.COONa; and (2) by the oxidation of many organic substances: starch, sugar, gelatin, fibrin, cellulose, tartaric and citric acids, etc. Commercially it is obtained as acetic acid and as vinegar. As the former it is produced by the dry distillation of wood, in which four products are obtained: charcoal, remaining in the retort, an illumi- nating gas, a tarry liquid, wood-tar, and an acid liquid, ' ' crude wood vinegar " or "pyroxylic spirit." The last is a highly complex liquid, containing acids of this series, methyl acetate, and cyclic compounds. It is redistilled fractionally, the first portions being used as a source of methylic alcohol, and the later portions of acetic acid. In these the acid is converted into sodium acetate, which, after calcination, is decomposed by H 2 S0 4 , and the liberated acetic acid distilled off. The product so obtained, the commercial acid, contains 36 per cent, of true acetic acid, sp. gr. 1.047. Vinegar is obtained by the indirect atmospheric oxidation of various alcoholic liquids, containing less than 10 per cent, of ethyl alcohol, under the influence of the growth of a true ferment, Bac- terium aceti, or ' ' mother of vinegar, ' ' with free access of air. It con- tains from 5 to 10 per cent, of acetic acid. Pure acetic acid, called glacial acetic acid (acidum aceticum glaciale, U. S. P.), is obtained by distilling dry sodium acetate with a slight excess of H 2 S0 4 . It is a colorless liquid, b. p. 119, crystal- lizes to an ice-mass at 17, sp. gr. 1.0497 at 20, having an acid taste and the odor of vinegar, and causing vesication when applied to the skin. Glacial acetic acid on dilution with water contracts until the sp. gr. becomes 1.0754 with a dilution of 77 per cent, of acid, cor- responding to a hydrate : CH 3 COOH-)-H 2 0, and on further dilution the sp. gr. diminishes until at 50 per cent, it is the same as that of the glacial acid. Acetic acid is a good solvent for many organic sub- CARBOXYLIC ACIDS 253 stances', and is itself soluble in water and in alcohol in all proportions. Vapor of acetic acid burns with a pale-blue flame and is decom- posed at a red heat. Glacial acetic acid only decomposes calcium car- bonate in the presence of water. Hot H 2 S0 4 blackens and decom- poses it, S0 2 and C0 2 being given off. Solutions of potassium acetate, when electrolyzed, yield ethane, C 2 H e . Under ordinary circumstances chlorine acts upon acetic acid slowly, more actively under the influ- ence of sunlight, to form the three products of substitution men- tioned below. Acetates are soluble in water, except basic ferric acetate. Potas- sium acetate, heated with arsenic trioxide forms cacodyl oxide. Cal- cium acetate, when heated alone, yields acetone; and with calcium formate, aldehyde. Monochloracetic acid is a solid, f.' p. 62, b. p. 186, obtained, along with acetyl chloride, by the action of chlorine upon acetic anhydride : (CH 3 .CO) 2 0+C1 2 =CH 2 C1.COOH+CH 3 .COC1 Dichloracetic acid is a colorless liquid, b. p. 190, obtained by heating chloral with aqueous potassium cyanide: CC1 3 .CHO+H 2 0+KCN=CHC1 2 .COOH+KC1+HCN Trichloracetic acid is an odorless, strongly vesicant, crystalline solid, f. p. 46, b. p. 195, obtained by oxidation of chloral hydrate by nitric acid: 2CC1 3 .CH(OH) 2 +0 2 =2CC1 3 .COOH+2H 2 Propan Acid Propionic Acid Methylacetic acid CH 3 .CH 2 .- COOH is formed by the action of caustic potash upon sugar, starch and gum; during acetic fermentation; in the distillation of wood; during the putrefaction of peas, beans, etc. ; by the oxidation of nor- mal propylic alcohol, etc. It is best prepared by heating ethyl cyanide with potash until the odor of the ester has disappeared; the acid 'is then liberated from its potassium compound by H 2 S0 4 and purified. It is a colorless liquid, sp. gr. 0.996, b. p. 140, solidifies at 36.5, odor and taste like those of acetic acid, mixes with water and alcohol. Its salts are crystalline and soluble. Butan Acid Butyric Acid Ethylacetic Acid CH 3 .CH,.CH 2 .- COOH exists in milk, perspiration, muscle, spleen, contents of stomach and large intestine, feces, and guano ; in butter, particularly when rancid; in certain fruits and in yeast. It is formed by the action of H 2 S0 4 and manganese dioxide, aided by heat, upon cheese, starch, gelatin, etc.; during the combustion of tobacco (as ammonium butyrate) ; by the action of HN0 3 upon oleic acid during the decomposition of many animal and vegetable substances, and par- ticularly by butyric fermentation of carbohydrates in presence of 254 TEXT-BOOK OF CHEMISTRY proteins. This fermentation occurs in two stages: First the glucose is converted into lactic acid: C 6 H- 12 6 =2C 8 H e Os ; and this in turn is decomposed into butyric acid, carbon dioxide, and hydrogen : 2C 3 H (! 3 =C 4 H 8 2 +2C0 2 +2H 2 . Butyric acid is a colorless, mobile liquid, having a disagreeable, persistent odor of rancid butter, and a sharp, acid taste; soluble in water, alcohol, ether, and methyl alcohol; boils at 164, distilling unchanged ; solidifies in a mixture of solid carbon dioxide and ether ; sp. gr. 0.974 at 15; a good solvent of fats. It is not acted on by cold H 2 S0 4 or HN0 3 . Hot HN0 3 oxidizes it to succinic acid: 2CH 3 .CH 2 .CH 2 .COOH+30 2 =2COOH;CH 2 .CH 2 .COOH+2H 2 Dry Cl in sunlight, and Br under heat and pressure form several products of substitution. The butyrates are soluble in water. Butyric acid is formed in the intestine, by the process of fermen- tation mentioned above, at the expense of those portions of the car- bohydrate elements of food which escape absorption, and is dis- charged with the feces as ammonium butyrate. Isobutyric Acid Dimethylacetic acid 3 ^> CH.COOH boils at 155, has been found in human feces. It corresponds to isobutyl alcohol, from which it is produced by oxidation. Pentan Acids Valerianic Acids Valeric Acids C 4 H 9 .COOH 102. Corresponding to the four primary amylic alcohols, there are four possible amylic or valerianic acids : Normal Valerianic Acid Valeric Acid Propyl-acetic acid is obtained by the oxidation of normal amylic alcohol. It is an oily liquid, boils at 185, and has an odor resembling that of butyric acid. Ordinary Valerianic Acid Valeric Acid Isopropyl-acetic acid Isovaleric acid This acid exists in the oil of the porpoise, and in valerian root and in angelica root. It is formed during putrid fer- mentation or oxidation of proteins. It occurs in the urine and feces in typhoid, 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. The ordinary valerianic acid is an oily, colorless liquid, having an odor of old cheese, and a sharp, acrid taste. It solidifies at 51 ; boils at 173-175; sp. gr. 0.9343-0.9465 at 20; burns with a white. smoky flame. It dissolves in 30 parts of water, and in alcohol ;mCH 2 .C1.COOH > CH 2 .OH.COOH > COOH.COOH (2) When the two carboxyls are attached to neighboring carbon atoms the acids are decomposed into water and an anhydride (p. 269) : C^TT f^O\ COOH.CH 2 .CH 2 .COOH^:H 2 0+ I ' CH 2 .CO/ (3) When the carboxyls are attached to remote carbon atoms their calcium salts are converted by heat into cyclic ketones and carbonate : /CH. 2 CH 2 .C0 2 \ n , /CH 2 .CH 2 \ Oxalic Acid COOH.COOH 90 C 2 H 2 4 , 2Aq 126 does not occur free 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 oxalate ; and in small quantity in human urine. It is prepared artificially by oxidizing sugar or starch by HN0 3 , or by the action of an alkaline hydroxide in fusion upon sawdust. 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 H 2 S0 4 or H 2 S ; 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 potash in fusion upon the alkaline formates; and by the action of K or Na upon C0 2 . 258 TEXT-BOOK OF CHEMISTRY It crystallizes in transparent prisms, containing 2 Aq, which effloresce on exposure to air, and lose their Aq slowly but completely at 100, or in a dry vacuum. It fuses at 98 in its Aq; at 110-132 it sublimes in the anhydrous form, while a portion is decomposed; above 160 the decomposition is more extensive; H 2 0, C0 2 , CO, and formic acid are produced, while a portion of the acid is sublimed un- changed. It dissolves in 15.5 parts of water at 10; the presence of HNO 3 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 CO 2 and H 2 0, slowly by simple exposure to air, more rapidly in the presence of platinum-black or of the salts of platinum and gold, under the influence of sunlight, or when heated with HN0 3 , man- ganese dioxide, chromic acid, Br, Cl, or hypochlorous acid. Its oxi- dation, when it is triturated dry with lead dioxide, is sufficiently active to heat the mass to redness. H 2 S0 4 , H 3 P0 4 and other dehy- drating agents decompose it into H 2 0, CO and C0 2 . Analytical Characters. (1) In neutral or alkaline solution: a white ppt. with a solution of Ca salt. (2) Silver nitrate: a white ppt, soluble in HN0 3 , and in NH 4 OH. 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 HN0 3 , insoluble in acetic acid. Toxicology. Although certain oxalates are constant constituents of vege- table food and of the human body, the acid itself, as well as monopotassic 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 4 gm. of the solid acid, and recovery a dose of 30 gm. 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 soluble salt of Ca or Mg, sus- pended or dissolved in a small quantity of H 2 or mucilaginous fluid; after- ward, if vomiting has not occurred spontaneously, and if the symptoms of corrosion have not been severe, an emetic may be given. The alkaline car- bonates 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 in- gestion of water, or the administration of warm water as an emetic, is contra- indicated \\hen the poison has been taken in the solid form (or where doubt exists as to what form it was taken in), as they dissolve, and thus favor the absorption of the poison. Malonic Acid CH 2\COOH~ is a P roduct of the oxidation of malic acid or of normal propyl glycol. II is best obtained by Hie general method . |i. -2~>7. Monochloracetic acid is converted into cyano-acetic acid by heating in alkaline solution with K( N : (II ,C1.COOH+KCN=CN.CH 2 .COOH+KC1 ALCOHOL-ACIDS OXYACIDS 259 The v cyano-acid is then hydrolyzed by heating with KOH or HC1, thus: CN.CH 2 .COOH-f2H 2 0=COOH.CH 8 .COOH+NH 8 It forms large prismatic crystals, soluble in water, alcohol and ether; fusible at 132, and decomposed at about 150 into acetic acid and carbon dioxide. CH 2 COOH Succinic Acid 118 exists in amber, coal, fossil wood, and CH 2 COOH in small quantity in animal and vegetable tissues. Its presence has been de- tected 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 quantity during alcoholic fermentation; as a product of oxidation of many fats and fatty acids; and by synthesis from ethylene cyanide: CN. ( CH 2 ) 2 .CN-f4H 2 0=COOH. ( CH 2 ) 2 .COOH-f-2NH 3 It may also be obtained by dry distillation of amber, or 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, and distils with partial decom- position at 235. It withstands the action of oxidizing agents. Reducing agents convert it into the corresponding acid of the fatty series, butyric acid. With Br it forms products of substitution. H 2 SO 4 is without action upon it. Phosphoric anhydrides remove H 2 O and convert it into succinic anhydride, C 4 H 4 3 . Glutaric Acid COOH. ( CH 2 ) 3 .COOH Normal Pyrotartaric acid the next superior homologue of succinic acid, is formed by reduction of a oxyglutaric acid (p. 263). It crystallizes in large plates, very soluble in water, which fuse at 27. The corresponding amido-acid is one of the products of decomposi- tion of protein bodies. ALCOHOL-ACIDS OXYACIDS. These acids contain, besides the carboxyl group, one of the groups CH 2 OH, CHOH, or COH, which characterize the primary, secondary, and tertiary alcohols. They, therefore, have the function of alcohols, primary, secondary, or tertiary, as well as that of acids : CH 2 OH CH 8 (CH 3 ) 2 COOH CHOH COH COOH COOH Gly collie acid aOxypropionic acid a Oxyisobutyric acid (primary). (secondary). (tertiary). They may be considered as derived either from the di- and poly- atomic alcohols (glycols, glycerols, etc.) by incomplete oxidation, as COOH.CH 2 OH from CH 2 OH.CH 2 OH ; or from the pure acids by sub- stitution of OH for H atoms in the remaining hydrocarbon groups, as CH 2 OH.CH 2 .CHU.COOH; CH 2 OH.CHOH.CH 9 .COOH, and CH 2 - OH.CHOH.CHOH.COOH from CH 3 .CH 2 .CH 2 .COOH. The basicity of these acids is represented by the number of car- boxyl groups which they contain, their atomicity by the number of hydroxyls. Thus CH 2 OH.CHOH.COOH is monobasic and triatomic. 260 TEXT-BOOK OF CHEMISTRY The algebraic formulae of the several monobasic series are CnH2nOs; CnH2n04, CnH2nOs, etc., those of the dibasic series CnH2 W -205, CnH2f-206, etc. ; and those of the tribasic series CnEbn-iO, CH2n-40s, etc. OXYACETIC SERIES. C n H 2n 8 The acids of this series contain one carboxyl and one alcoholic group. They are, therefore, monobasic and diatomic, and may be considered as derived from the glycols by oxidation of one CH 2 OH group, or from the acids of the acetic series by substitution of OH for H in a hydrocarbon group (oxyacetic). They are formed: (1) By the limited oxidation of the correspond- ing glycols or oxyaldehydes : CH 2 OH.CH 2 OH+0 2 =CH 2 OH.COOH+H 2 0, or 2CH 2 OH.CHO+0 2 =2CH 2 OH.COOH (2) By the action of nascent hydrogen upon the aldehyde or ketone acids, or upon the acids of the oxalic series: CHO.COOH+H,=CH 2 OH.COOH, or CH 3 .CO.COOH+H 2 =CH 3 .CHOH.COOH, or COOH.COOH+2H 2 =CH 2 OH.COOH+H 2 O (3) By heating the monohalogen fatty acids with silver or po- tassium hydroxides, or with water: CH 2 C1.COOH+KHO=CH 2 OH.COOH+KC1, or CH 2 C1.COOH+H 2 0=HC1+CH 2 OH.COOH (4) From the aldehydes and ketones, by their conversion, first into oxycyanides by the action of hydrocyanic acid: CH 3 .CHO+HCN=CH 3 .CH /g and the action upon these of acids or alkalies: CH 3 .CH /* +2H 2 0=CH 3 .CHOH.COOH+NH 3 Isomeres Position or Place Isomery. Considering the oxybutyric acids as derived from normal and isobutyric acids by substitution of one OH for a hydrogen atom in a hydrocarbon group, the following five derivatives are possible: I. II. III. IV. V. CH, CH, CH, CH 2 OH H,C CH, H,C CH 2 OH H,C CH, CH 2 CH 3 CHOH CH 2 \/ CH \/ CH \/ COH CH 2 CHOH CH a CH 2 COOH COOH COOH COOH COOH COOH COOH Alpha Beta (Jamma Beta Alpha Normal o\y oxy ONV- Isobutyric Oxyisobutyric Oxyisobutyric I'.utyrir acid. butyric acid. butyric acid. butvrle acid. acid. ucid. acid. ALCOHOL-ACIDS OXYACIDS 261 Whi\e III, IV, and V are obviously different in molecular structure from each other and from I and II, in that the latter contain the group CHOH, while^the former contain the groups CH,OH,CH, and COH, the only difference between I and II, whose molecules are composed of identical groups, is in the position or place of the alcoholic hydroxyl with reference to the carboxyl group. Place isomeres of this kind are distinguished by designating that in which the second substituted group (in this case the OH) is attached to the carbon atom contiguous to the first as the alpha, or 1 -compound, and the others by the succeeding Greek letters, or by the numerals in the order of the removal of the position of the second substitution. Thus II above is Beta oxybutyric or 2-oxybutyric acid. (See Orientation, p. 337.) The a, /3, y-^ and 6 acids differ in their products of dehydration: The acids yield cyclic double esters, called lactids, by elimination of H 2 from two molecules of the acid. The /3 acids are converted into unsaturated acids by loss of H 2 O from one molecule of the acid: CH 2 OH.CH 2 .COOH=CH 2 : CH.COOH-f-H 2 O. The y and 6 acids and those of greater carbon content, are converted into simple cyclic esters, called lactones, by elimination of H 2 O from a single molecule of the acid. By further oxidation the primary oxyacids containing CH 2 OH yield alde- hyde acids: and then dibasic acids: 2CHO.COOH-f 2 =2COOH.COOH ; The secondary acids, containing CHOH, yield ketone acids: 2CH 3 .CHOH.COOH+0 2 =2CH 3 .CO.COOH+2H 2 0, And the tertiary acids, containing COH, yield ketones, carbon dioxide and water : 2 cg 3 ^) COH.COOH-f-0 2 =2CH 8 .CO.CH 3 -f 2C0 2 -j-2H 2 O. The hydrogen of their carboxyl group may be replaced to form salts, esters, or amides; and the hydroxyl of their alcoholic group may be replaced by alkali metals, alkyls, or acidyls. In other words, they behave as acids and as alcohols. Oxy formic Acid Carbonic acid OC(OH) 2 . Although, this acid does not exist free, but is decomposed as soon as liberated into C0 2 and H 2 0, its salts, the carbonates, are well known and quite stable. The position of this acid in this series is an apparent anomaly, as it is dibasic, not monobasic like the other terms of the series. But if we bear in mind that the basic nature of the H atom in a hydroxyl depends upon its close union with a CO group (or some other electro-negative group), it is evident that the two H atoms in the inferior homologue of glycollic acid, being similarly united to the same CO group, must be equally basic : CH 2 OH /OH | CH 2 = OC COOH \OH Glycollic acid, Carbonic acid. Indeed, carbonic acid is not an alcohol acid, but a pure acid, as it contains no alcoholic group. 262 TEXT-BOOK OF CHEMISTRY Esters are also known corresponding to orthocarbonic acid: C(OH) 4 although the acid itself is unknown. Glycollic Acid Oxyacetic acid CH 2 OH.COOH is formed by the oxidation of glycol, by the action of nitrous acid upon glycocoll, and by the action of KOH upon monochloracetic acid, or upon glyoxal, CHO.CHO. It forms deliquescent acicular crystals, very soluble in water, alco- hol and ether. It fuses at 80 . It is oxidized by HN0 3 to oxalic acid. Lactic Acids Oxypropionic acids Alpha oxypropionic acid Efhidene lactic acid CH 3 .CHOH.COOH is formed from milk sugar, cane sugar, gum and starch by lactic fermentation, induced by the lactic acid bacillus. It consequently exists Ifc many soured products, such as soured milk, sour-krout, fermented beet-juice, and the waste liquors of starch works and of tanneries. It is formed in the stomach during digestion of carbohydrates. It is prepared by allowing a mixture of cane sugar, tartaric acid, rotten cheese, skim milk and chalk to ferment for ten days at 35. It has also been obtained by oxidation of alpha propylene glycol: CH 3 .CHOH.CH 2 OH+0 2 =CH 3 .CHOH.COOH+H 2 Lactic acid of fermentation is a colorless, or yellowish, syrupy liquid; sp. gr. 1.215 at 20; soluble in water, alcohol and ether. It does not distil without decomposition, but when heated it yields lactid, carbon monoxide, aldehyde and water. Heated to 130 with dilute sulphuric acid it splits into aldehyde and formic acid: CH 3 CHOH.COOH=CH 3 .CHO+H.COOH Oxidizing agents convert it into pyroracemic acid: CH 3 .CO.- COOH, or, if more energetic, split it up into acetic acid and carbon dioxide : CH 3 .CHOH.COOH+0 2 =CH 3 .COOH+C0 2 +H 2 Hydriodic acid reduces it to propionic acid ; but hydrobromic acid converts it into <*-bromopropionic acid. Ethidene lactic acid contains an asymmetric carbon atom (p. 239) : CH 3 .C*HOH.COOH; and that produced by lactic fermentation is optically inactive (d+1). The dextro acid, also known as sarcolactic or paralactic acid, is best obtained from Liebig's meat extract; and is also produced by allowing Penicillium glaucum to grow in a solu- tion of inactive ammonium lactate. It exists in muscular tissue after death y and during contraction, and in the spleen, lymphatic glands, thymus, thyroid, blood, bile, transudates, in the perspiration in puer- peral fever, and in the urine after violent exercise, in yellow atrophy of the liver and in phosphorus poisoning, either free or in com- bination. The acid in muscular tissue probably originates from glycogen. ALCOHOL-ACIDS OXYACIDS 263 Laevolactic Acid is formed by the growth of Bacillus acidi Ice- volactici in a solution of cane sugar. Ethylene Lactic Acid Beta oxypropionic acid Hydracrylic acid CH 2 OH.CH 2 .COOH the third form of lactic acid, is formed by the action of moist silver oxide upon /?-iodo- or /?-chloropropionic acid ; by the saponification of ethylene cyanhydrine ; or by the oxida- tion of the corresponding glycol. It is a thick, uncrystallizable syrup, which is converted by dehydration into acrylic acid: CH 2 OH.CH 2 .COOH=CH 2 :CH.COOH+H 2 0. On oxidation it yields oxalic acid and carbon dioxide : 2(CH 2 OH.CH 2 .COOH)+50 2 =2(COOH.COOH)+2C0 2 +4H 2 Oxybutyric Acids. Five isomeres are possible (p. 260). Beta oxybutyric acid CH 3 .C*HOH.CH 2 .COOH, is formed by the action of sodium amalgam upon acetoacetic ester: CH 3 .CO.CH 2 .COOH-f H 2 =CH 3 .CHOH.CH 2 .COOH. The Isevo-acid, a colorless syrup, readily soluble in water, alcohol and ether, occurs, accompanied by acetoacetic acid, in the blood and urine in severe cases of diabetes. MONOXYDICARBOXYLIC SERIES C n H 2n _ 2 O 5 . The acids of this series contain two carboxyls and one alcoholic group. They are, therefore, dibasic and triatomic, and may be considered as derived from the glycerols by oxidation of both CH 2 OH groups. They may also be considered as derived from the paraffin dicarboxylic acids (oxalic series), above the first, by substitution of OH for H in a hydrocarbon group, in the same manner as the acids of the oxyacetic series are derived from those of the acetic series. Tartronic Acid Oxymalonic acid COOH.CHOH.COOH is formed by the action of moist silver oxide upon monochloro- or monobromo-malonic acid, or by oxidation of glycerol by potassium permanganate. It crystallizes in large prisms, readily soluble in water, alcohol, and ether, and fusible at 184. Malic Acid Oxysuccinic acid COOH.CH 2 .C*HOH.COOH exists in three modifications. The laevo-acid exists free, and in combination with K, Na, Ca, Mg, and organic bases in apples, pears, and similar fruits, and in the berries of the mountain ash and in gooseberries. The inactive (d-(-l) acid may be obtained from monobromo-succinic acid by the action either of moist silver oxide, of dilute HC1, of dilute NaOH, or even of boiling water; and by several other methods. The dextro-acid is obtained by the reduction of dextro-tartaric acid by hydriodic acid. The natural malic acid crystallizes in prismatic needles; odorless; acid in taste; fusible at 100; deliquescent; very soluble in water and in alcohol. Heated to 140 it loses water with formation of fumaric acid, COOH.CH rCH.COOH. CH.CO\ At 180 it yields water, fumaric acid and maleic anhydride, || O. CH.CO/ Reducing agents convert it into succinic acid. The malates are oxidized to carbonates in the body. Oxyglutaric Acid exists in the two isomeres: a oxyglutaric acid, COOH.- CH(OH).CH 2 .CH 2 .COOH, which occurs in molasses, crystallizes with difficulty, and fuses at 72; and /? oxyglutaric acid, COOH.CH 2 CHOH.CH 2 .COOH, which fuses at 95. 264 TEXT-BOOK OF CHEMISTRY DIOXYDICARBOXYLIC ACIDS C n H 2n _A- Tartaric Acids Dioxyethylene Succinic Acids. COOH.CHOH.- CHOH.COOH (and see p. 160) There exist four acids having the composition C 4 H 6 6 , which are readily convertible one into the other. They are: Dextro-tartaric, or ordinary tartaric acid; Icevo-tartaric acid; mesotartaric, or antitartaric acid; and racemic, or paratartaric acid. The first three of these are stereoisomeres, due to the presence of two asymmetric carbon atoms in the molecule, whose molecular struc- ture has been discussed under the head of space isomery (p. 239). Mesotartaric acid, which is optically inactive, has a molecular struc- ture differing from those of the d- and 1- acids, into which it cannot be split. Racemic acid, also optically inactive, is the (d-J-l) acid, and can be readily decomposed into them or separated from a mix- ture of them. Dextro-tartaric Acid Ordinary tartaric acid Acidum tartaricum (U. S. P.) occurs, both free and in combination, in the sap of the vine and in many other vegetable juices and fruits, particularly in grape-juice. Although this is probably the only tartaric acid existing in nature, all four varieties may 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. The ordinary tartaric acid crystallizes in large prisms ; very solu- ble in H 2 and in alcohol; acid in taste and reaction. Heated with water at 165-175 it is converted into mesotartaric and racemic acids. It fuses at 170; at 180 it loses H 2 0, and is gradually con- verted into an anhydride; at 200 -210 it is decomposed with forma- tion of pyruvic acid, C 3 H/) 3 , and pyrotartaric acid, C 5 H 8 4 ; at higher temperatures C0 2 , CO, H 2 0, hydrocarbons and charcoal are produced. Tartaric acid is attacked by oxidizing agents with formation of C0 2 , H 2 0, and, in some instances, formic and oxalic acids. Certain reducing agents convert it into malic and succinic acids. With fum- ing HN0 3 it forms a dinitro-compound, which is very unstable, and which, when decomposed below 36, yields tartaric acid. It forms a precipitate with lime-water, soluble in an excess of H 2 0. In not too dilute solution it forms a precipitate with potassium sulphate solution. It does not precipitate with the salts of Ca. When heated with a solution of auric chloride it precipitates the gold in the metallic form. When taken into the economy, as it frequently is in the form of tartrates, 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. The acids and its salts are largely used in pharmacy and in dyeing. (See p. 160.) ALDEHYDE-ACIDS 265 Lcevb-tartaric forms crystals similar to those of the dextro acid, but having opposite hemihedral facets, so that the crystals of one acid "resemble the reflection of those of the other in a mirror. Racemic Acid (d+l) Tartaric acid is produced when concen- trated solutions of equal quantities of d- and 1-tartaric acids are mixed. It is formed by oxidation of dulcitol and of mannitol. It is obtained by the action of moist silver oxide upon dibromo succinic acid: COOH.CHBr.CHBr.COOH+2AgOH=COOH.CHOH.- CHOH.COOH+2AgBr; and by several other synthetic methods. It crystallizes in rhom- bic prisms, less soluble in water than ordinary tartaric acid, and fuses at 205. Mesotartaric Acid Inactive Tartaric acid is obtained by oxida- tion of erythrol ; or by heating dextrotartaric acid with water at 165 for two days. HIGHER DICARBOXYLIC OXYACIDS. The carbohydrates, on oxidation with nitric acid, yield tetroxydicarboxylic acids: COOH.(CHOH) 4 .COOH. Among these are: mannosaccharic acids; saccharic acids; and mucic acid. Of the three saccharic acids the d-acid is the best known. It is produced by oxidation of many carbohydrates, including cane sugar and grape sugar, by nitric acid, and by the action of bromine water on glucuronic acid. Nascent H reduces it to glucuronic acid. It forms a syrup or a deliquescent solid, which, on standing, changes to a crystalline lactone. Mucic acid is produced by the oxidation of dulcitol, milk sugar, and the gums. It is a white solid, almost insoluble in cold water and in alcohol, which fuses at 210. OXYTRICARBOXYLIC ACIDS C n H 2rt _A. /CH 2 .COOH Citric Acid HO.C COOH , exists in the juices of many fruits, lemon, \CH 2 .COOH strawberry, currant, and in small quantity, as calcium citrate, in cow's milk. It is obtained commercially from lemon juice. It crystallizes in large, rhombic prisms, very soluble in water and in alcohol. It fuses at 100 ; at 175 it is decomposed with loss of water and formation of aconitic acid; and at a higher temperature C0 2 is given off and citraconic and itaconic acids are produced. In the body its salts are oxidized to carbonates. ALDEHYDE-ACIDS. These are substances having both aldehyde and acid functions, and con- taining the groups CHO and COOH. The simplest of the class is formic acid, already referred to as the first term of the acetic series, in which, however, the /TT carbon atom is common to the two groups : O : C / Glyoxylic Acid CHO. COOH when produced unites with water to form a hydrate: (OH) 2 :CH.COOH, corresponding to chloral hydrate: (OH) 2 :CH.CC1 3 . 266 TEXT-BOOK OF CHEMISTRY This is a thick syrup, or it forms rhombic prisms. It is produced by heating dichloracetic acid with water at 230: CHCl 2 .COOH-j-H 2 O=CHO.COOH-|-2HCl. It has the reducing power and other properties of the aldehydes. KETONE-ACIDS. These compounds contain both the ketonic and carboxyl groups, CO and COOH. The monoketone-monocarboxylic acids contain one CO and one COOH. According as the CO group occupies the position adjacent to the carboxyl, or further removed therefrom, these acids are designated as a, /3, y, etc.; thus CH 8 .CH 2 .CO.COOH=a, CH 3 .CO.CH 2 .COOH=/3, etc. The a, -y, 6, etc., acids are much more stable than the /3 -acids, and may be obtained by oxidation of the corresponding secondary alcohol acids. The a acids are derivable from formic acid by substitution of acidyls for the extra- carboxylic hydrogen: (CH 3 .CO) .COOH. Pyruvic Acid Pyroracemic acid CH 3 .CO.COOH is formed by oxidation of a-oxypropionic acid: 2CH 8 .CHOH.COOH-(-O 2 :=2CH 3 .CO.COOH-|-2H. ! O. It is also formed by distillation of tartaric acid: COOH.CHOH.CHOH.COOH=CH 8 .CO.COOH+C0 2 4-H 2 0. The /3 -ketone acids are more unstable, and are decomposed by heat with formation of ketone and carbon dioxide: COOH.CH 2 .CO.CH 3 =C0 2 -fCH 8 .CO.CH 8 . Their esters are, however, quite stable, and are employed in many syntheses. The /3 acids bear the same relation to acetic acid that the a acids do to formic acid : ~ ( CH 8 .CO ) ,CH 2 .COOH. Aceto-acetic Acid Diacetic Acid CH 3 .CO.CH 2 .COOH may be obtained as a thick, strongly acid liquid by saponification of its esters. Heat decomposes it into acetone and carbon dioxide, according to the equation given above. Aceto-acetic acid accompanies /3 oxybutyric acid and acetone in the urine in diabetes. (See Aceto-acetic ester, p. 278). Mesoxalic Acid Dioxymalonic acid HO/ C \COOH~~ is the monoketone - dicarboxylic acid, COOH.CO.COOH, combined with water in the same manner as chloral hydrate and glyoxylic acid. Esters are known corresponding to both forms: oxymalonic esters, CO: (COO.C 2 H 5 ) 2 , and dioxymalonic esters, C(OH) 2 :(COO.C 2 H B ) 2 . Mesoxalic acid is obtained by the action of boiling barium hydroxide upon dibromomalonic acid: COOH.CBr 2 .COOH4-Ba ( OH ) 2 =COOH.C ( OH ) 2 .COOH-f BaBr 2 , or upon alloxan (mesoxalylurea) . It crystallizes in prisms, very soluble in water, fusible at 115. On evaporation of its aqueous solution it decomposes into carbon monoxide, water and oxalic acid; at higher temperatures it yields carbon dioxide and glyoxylic acid. OXYALDEHYDE AND OXYKETONE ACIDS. These acids contain alcoholic groups, CH 2 OH, CHOH, or COH in addition to carboxyl and cither tin- aldehyde or ketone group, CHO or CO. Glucuronic Acid CHO. (CHOH) 4 .COOH is a derivative of glucose: CHn. (( Il< IH | 4 .CH 2 OH. It is a syrup which passes into a crystalline lactone SIMPLE ETHERS 267 on ivarmihg. It occurs in the urine in small quantity normally, in combination with phenol, skatole and indole, and with camphors, chloral and other sub- stance^ when these are present. SIMPLE ETHERS. These substances have been referred to (p. 209) as the simplest products of oxidation of the hydrocarbons. The term ether was for- merly applied to any substance produced by the action of an acid upon an alcohol. Such products belong, however, to two distinct classes : (1) The simple ethers, or ethers, which are the oxides of the hydrocarbon radicals, and the counterparts of the metallic oxides, bearing the same relation to the alcohols that the metallic oxides do to their hydroxides: CH 3 .CH 2 \ CH 3 .CH 2 \ K\ H\ CH 3 .CH 2 / U H/ u K/ u Ethyl oxide. Ethyl hydroxide. Potassium Potassium (Ether.) (Alcohol). oxide. hydroxide. (2) The compound ethers, now called esters, which are the products of the reaction between an acid and the alcohol, the latter behaving as a basic hydroxide. They are the counterparts of the metallic salts: CH 3 CH 2 .0\ qo CH 3 .CH 2 0\~ n K0\ fin HO/ &U2 CH 3 .CH 2 0/ bU2 HO/ bUa Monoethylic Diethylic Monopotassic Dipotassic sulphate. sulphate. sulphate. sulphate. (Ester-acid.) (Neutral ester.) (Acid salt.) (Neutral salt.) Mixed ethers differ from simple ethers in that they contain differ- ent, in place of similar, alkyls, as methyl-ethyl oxide: CH 3 .O.CH 2 .- CH, Simple and mixed ethers are formed: (1) By interaction of the alcohols and alkyl-sulphuric acids. Thus methyl-sulphuric acid and ethylic alcohol form methyl-ethyl oxide: S0 2 \OH H '+C 2 H 5 .O.H=C 2 H 5 .O.CH 3 +S0 2 :(OH) 2 (2) By the action of alkyl halides upon sodium alcoholates: CH 3 .Cl+C 2 H 5 O.Na=NaCl+C 2 H 5 .O.CH 3 (3) By the action of silver oxide upon alkyl halides: 2C 2 H 5 I+ Ag 2 0=2AgI+0 ( C 2 H 5 ) , Methyl oxide CH 3 .O.CH 3 46 isomeric with ethyl alcohol, is obtained by the action of silver oxide upon methyl iodide, or by the action of H 2 S0 4 and boric acid upon methyl alcohol. It is a colorless gas, has an ethereal odor, burns with a pale flame, liquefies at 36 and boils at 21 , is soluble in H 2 0, H 2 S0 4 and ethylic alcohol. 268 TEXT-BOOK OF CHEMISTRY Ethyl Oxide Eihylic ether Sulphuric ether JEther (U. S. P.) C 2 H 5 .O.C,H 5 . In the manufacture of ether a mixture is made of 5 pts. of 90% alcohol and 9 pts. of concentrated H 2 S0 4 , in a vessel surrounded by cold water. This mixture is introduced into a retort, into which a slow stream of alcohol is allowed to flow during the remainder of the process. Heat, so regulated as not to exceed 140, is then applied to the retort, which is connected with a well-cooled condenser, and continued until the temperature rises above the point indicated. The distillate contains ether, alcohol, water and dissolved gases, notably S0 2 . It is shaken with water containing potash or lime, and the ether decanted off. The product is " washed ether." For further purification it is treated with calcium chloride, or re- cently burnt lime, with which it is left in contact for 24 hours, and from which it is then distilled. In the conversion of alcohol into ether, sulphovinic or ethyl-sul- phuric acid behaves as a "contact substance" and serves to carry an ethyl radical from one alcohol molecule to another, with formation of water and regeneration of sulphuric acid. In the first stage of the reaction ethyl-sulphuric acid is formed by the action of H 2 S0 4 upon alcohol, molecule for molecule: H 2 S0 4 +C 2 H 5 .OH=H 2 0+C 2 H 5 .HS0 4 The ethyl-sulphuric acid then reacts with another molecule of alcohol, according to the general reaction (1) for the formation of ethers, to form ether and sulphuric acid: C 2 H 5 .HS0 4 +C 2 H 5 .OH=H 2 S0 4 +(C 2 H 5 ) 2 It would seem, therefore, that a given quantity of H 2 S0 4 could convert an unlimited amount of alcohol into ether. But the gradual accumulation of the.H 2 formed in the first stage of the reaction, and the occurrence of secondary reactions in practice limit the amount of ether produced to about four or five times the bulk of acid used. Ether is a colorless liquid; has a sharp, burning taste, and a peculiar, tenacious odor, characterized as ethereal. Sp. gr. 0.723 at 12.5; it boils at 34.5. Its tension of vapor is very great, especially at high temperatures ; and it is exceedingly volatile. Water dissolves one-ninth its weight of ether. Ethylic and methylic alcohols are miscible with it in all proportions. Ether is an excellent solvent of many substances not soluble in water and alcohol. The resins and fats are readily soluble in ether. The salts of the alkaloids and many vegetable coloring matters are soluble in alcohol and water, but in- soluble in ether, while the free alkaloids are for the most part soluble in ether, but insoluble, or very sparingly soluble, in water. Ether is highly inflammable; and burns with a luminous flame. The vapor forms with air a violently explosive mixture. It is denser than air, through which it falls and diffuses itself to a great dis- ACID ANHYDRIDES 269 tance ; caution is therefore required in handling ether in a locality in which there is a light or fire, especially if the fire be near the floor. Pure ether is neutral in reaction. H 2 S0 4 mixes with it, with elevation of temperature, and formation of sulphovinic acid. With sulphuric anhydride it forms ethyl sulphate. HN0 2 , aided by heat, oxidizes it to carbon dioxide and acetic and oxalic acids. Ether, saturated with HC1 and distilled, yields ethyl chloride. Cl, in the presence of H 2 0, oxidizes it, with formation of aldehyde, acetic acid, and chloral. In the absence of H 2 0, however, a series of products of substitution are produced, in which 2, 4, and 10 atoms of H are re- placed by a corresponding number of atoms of Cl. These substances in turn, by substitution of alcoholic radicals, or of atoms of elements, for atoms of Cl, give rise to other derivatives. Ethylene Oxide njj /^ * s a cyclic ether corresponding to glycol: CH 2 OH.CH 2 OH=(CH 2 ) 2 O-f-H 2 O, as ethyl oxide corresponds to ethylic alcohol: 2CH 3 .CH 2 .OH= ( C 2 H 5 ) 2 O+H 2 O It is prepared by the action of caustic potash on ethylene chlorhydrine : CH 2 OH.CH 2 C1+ KOH= ( CH 2 ) 2 0+KC1+H 2 It is a volatile liquid, boils at 13.5, is neutral in reaction and mixes with water. It unites with H 2 O to form glycol, and with HC1 to regenerate ethylene chlorhydrine. Nascent H converts it into ethyl alcohol. ACID ANHYDRIDES. The acid anhydrides are the oxides of the acid radicals (acidyls) ; and bear the same relation to the acids that the simple ethers bear to the alcohols: CH 3 COOH CH 3 .CH 2 OH Acetic acid. Ethylic alcohol. CH 3 .CO\ CH 3 .CH 2 \ CH 3 .CO/ U CH 3 .CH 2 / U Acetic anhydride. Ethylic ether. The acid anhydrides of the monobasic acids are produced by the action of the acidyl chlorides upon anhydrous salts: C 2 H 3 O.OK+C 2 H 3 O.C1=:(C 2 H 3 0) 2 0+KC1 or by the action of phosphorus oxychloride upon the alkali salts of the acids. In this method of formation the acidyl chloride is first produced : 2C 2 H 3 O.OK+POC1 3 =2C 2 H 3 O.C1+P0 3 K+KC1; and this acts upon an excess of the salt according to the above equation. Formic acid produces no anhydride. Acetic Anhydride (C 2 H 3 0) 2 is a pungent liquid which boils 270 TEXT-BOOK OF CHEMISTRY at 137. It is formed by the general methods and also by heating lead acetate with carbon disulphide at 165. It serves for the intro- duction of the radical acetyl into other molecules. ACIDYL HALIDES. These compounds, also known as halide anhydrides, are the halo- gen compounds of the acidyls. They are produced: (1) By the action of the phosphorus halides upon the acids or their salts : 3CH 3 .COOH+PC1 3 =3CH 3 .COC1+P0 3 H 3 ; or 2CH 3 .COOK+ POC1 3 =2CH 3 .COC1+P0 3 K+ KC1 ; or CH 3 .COOH+PC1 5 =CH 3 .COC1+POC1 3 +HC1 (2) By the action of phosgene upon the acids, or their salts: COC1 2 +CH 3 .COOH=CH 3 .CO.C1+C0 2 +HC1 (3) By the action of phosphorus pentoxide upon the acids in presence of hydrochloric acid: 3CH 3 .COOH+3HC1+P 2 5 =3CH 3 .CO.C1+2P0 4 H 3 ; or (4) By the action of chlorine upon the aldehydes: C1 2 +CH 3 .CO.H=CH 3 .CO.C1+HC1 Acetyl Chloride CH 3 .CO.C1 is a colorless, pungent liquid, which boils at 55. It is decomposed by water with formation of acetic and hydrochloric acids. With acetic acid it forms acetic an- hydride. It is used to produce acetyl derivatives. OXIDES OF CARBON. The two oxides of carbon are also anhydrides in that they combine with water to produce acids, or, what amounts to the same thing, with KOH to form the K salts, thus : CO + KOH H.COOK Carbon Potassium Potassium monoxide. hydroxide. formate. C0 a + KOH 0:C\QK Carbon Potassium Monopotassic dioxide. hydroxide. carbonate. Carbon Monoxide Carbonous oxide Carbonic oxide CO 28 is formed: (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 sulphuric acid: C 2 4 H 2 =H 2 0+CO+C0 2 and passing the gas through sodium hydroxide to separate C0 2 . (4) By heating potassium ferrocyanide with H 2 S0 4 . OXIDES OF CARBON 271 It is a colorless, tasteless gas: sp. gr. 0.9678A; very sparingly soluble in H 2 and in alcohol. It burns in air with a blue flame to C0 2 , and it forms explosive mixtures with air and oxygen. 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 non-saturated, it unites readily with to form CO 2 , and with Cl to form COC1 2 , the latter a colorless, suffo- cating gas, known as phosgene, or carbonyl chloride, which is of service in the formation of acid chlorides and anhydrides and in a variety of other syntheses. 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, from open coal or charcoal fires and of illuminating gas. Poisoning by CO may occur in several ways. By inhalation of the gases discharged from blast-furnaces and from copper-furnaces, the former contain- ing 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 consists of a mix- ture of the two oxides of carbon, the dioxide predominating largely, especially when the combustion is most active. The following is the composition of an atmosphere produced by burning charcoal in a confined space, and which proved rapidly fatal to a dog: oxygen, 19.19; nitrogen, 76.62; carbon dioxide, 4.61; carbon monoxide, 0.54; marsh-gas, 0.04. Obviously the deleterious effects of charcoal-fumes are more rapidly fatal in proportion as the combus- tion 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 the reduction of the dioxide, also formed, passing over red-hot iron. Fatal poisoning by illuminating gas is of very frequent occurrence. The most actively poisonous ingredient of illuminating gas is CO, which exists in ordinary coal-gas in the proportion of 4 to 7.5 per cent., and in water-gas, made by decomposing 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 oxyhemoglobin, 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 hemo- globin is quite stable, and hence the symptoms of this form of poisoning are very persistent, lasting until the place of the coloring-matter thus rendered useless is supplied by new formation. The prognosis is very unfavorable when the amount of the gas inhaled has been at all considerable, the treatment usually followed, i.e., artificial respiration and inhalation of 0, restoring the altered coloring matter very slowly. There would seem to be no form of poisoning in which transfusion of blood is more directly indicated than in that by CO, but it has been found to be detrimental rather than beneficial. Detection after death. The blood of those asphyxiated by CO is per- sistently bright-red in color. When suitably diluted and examined with the spectroscope, it presents an absorption spectrum (No. 6, Fig. 19, p. 273) of two bands similar to that of oxyhi-moglobin (No. 3, Fig. 19), but in which 272 TEXT-BOOK OF CHEMISTRY 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 oxyhemoglobin to the single-band spectrum of hemo- globin (No. 1, Fig. 19), while that of the CO compound remains unaltered, or only fades partially. If a solution of caustic soda of sp. gr. 1.3 is 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. A piece of gun-cotton upon which platinum-black has been dusted fires in air containing 2.5 in 1,000 of CO. Carbon Dioxide Carbonic anhydride Carbonic acid gas C0 2 44 is obtained: (1) By burning C in air or 0. (2) By de- composing a carbonate (marble=CaCO 3 ) by a mineral acid (HC1 diluted with an equal volume of H 2 0). At ordinary temperatures and pressures it is a colorless, suffo- cating gas; has an acidulous taste; sp. gr. 1.529 A; soluble in an equal volume of H 2 at the ordinary pressure, much more soluble as the pressure increases. Soda water is a solution of carbonic acid in H 2 under increased pressure. When compressed to the extent of 38 atmospheres at 0; 50 atm. at 15; or 73 atm. at 30 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 or ice-like mass, which, by spontaneous evaporation in air, produces a temperature of 90. Carbon dioxide neither burns nor does it support combustion. When heated to 1,300, it is dissociated into CO and 0. A similar decomposition is brought about by the passage through it of electric sparks. When heated with H it yields CO and H 2 0. When K, Na, or Mg is heated in an atmosphere of C0 2 , the gas is decomposed with formation of a carbonate and separation of carbon. When caused to pass through solutions of the hydroxides of Na, K, Ca, or Ba, it is absorbed, with formation of the carbonates of those metals, which, in the case of the last two, are deposited as white precipitates. Solution of potash is frequently used in analysis to absorb C0 2 , and lime and baryta water as tests for its presence. The hydroxides mentioned also absorb C0 2 from moist air. Atmospheric Carbon Dioxide. Carbon dioxide exists in- free country air in the proportion of about four parts in 10,000. Its sources are from: (1) Respiration. Expired air contains about 4.5 per cent. C0 2 . (2) Combustion of fuel, illuminating gas, etc. A burner consuming three cubic feet of illuminating gas per hour produces as much C0 2 as is formed by the respiration of seven human beings. In a confined space respiration and combustion vitiate the OXIDES OP CARBON 273 40 FIG. 19. Spectra of: (1) Reduced hemoglobin; (2) Oxyhemoglobin, con- centrated; (3) Same, dilute; (4) Same, very dilute; (5) Methemoglobin, in faintly alkaline solution; (6) Carbon monoxide hemoglobin; (7) Hemochromo- gen, in alkaline solution; (8) Hematin, in acid solution; (9) Hematin, in alka- line solution; (10) Hematoporphyrin, in acid solution. 274 TEXT-BOOK OF CHEMISTRY air in two ways: by addition of carbon dioxide and by removal of oxygen, as the C0 2 is produced at the expense of atmospheric oxygen. By the other methods of its origin it is merely added to the air, whose oxygen-content remains nearly unaltered. (3) Fermentation. For every liter of alcohol produced 384 liters of C0 2 are added to the air. (4) Tellural sources, such as volcanic fissures, volcanoes, spring waters. (5) Manufacturing operations, such as lime-burning, cement and brick-making, iron furnaces, etc. (6) In coal mines the after- damp contains a volume of C0 2 equal to that of the fire-damp ex- ploded. Notwithstanding the large amounts of C0 2 discharged into the atmosphere from these several sources, and it is estimated that the amount is sufficient to double the atmospheric C0 2 -content in about eighty years, no increase in the normal proportion of C0 2 in free air has been observed. This is due to the constant removal of CO, from the air by plants, the green pigment of which, chlorophyll, decomposes C0 2 under the influence of sunlight, retaining the carbon in organic combination, and returning oxygen to the air. Action on the Economy. An animal introduced into an atmosphere of pure CO 2 dies almost instantly, and without entrance of the gas into the lungs, death resulting from spasm of the glottis, and consequent apnopa. When the proportion of O is not diminished, the poisonous action of CO, 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 pt-r cent. N, and 20 per cent. CO 2 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. C0 2 . If CO 2 is 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 2 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. When present in large proportion, CO 2 produces immediate loss of muscular power, and death without a struggle; when more dilute, a sense of irritation of the larynx, drowsiness, pain in the head, giddiness, gradual loss of muscular power, and death in coma. If the CO 2 present in air is produced by respiration, or combustion, 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. CO 2 , is much more rapidly fatal than one composed of 21 per cent. O, 59 per cent. N, 20 per cent. CO 2 . With a corresponding reduction of O, 5 per cent, of C0 2 renders 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 2 consists in the inhalation of pure air (to which an excess of O may be added), aided, if necessary, by artificial respiration, the cold douche, galvanism, and friction. Detection of Carbon Dioxide and Analysis of Confined Air. Carbon dioxide, or air containing it, causes a white precipitate when caused to bubble ESTERS COMPOUND ETHERS 275 through Jime 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 is contained, burns readily in the presence of 8 per cent, of CO 2 ; is perceptibly dulled by 10 per cent.; is usually ex- tinguished with 13 per cent.; always extinguished with 16 per cent. Its ex- tinction is caused by a less proportion of CO 2 , 4 per cent., if the quantity of O be at the same time diminished. Moreover, a contaminated atmosphere may not contain enough CO 2 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 2 in a gaseous mixture is determined by its absorption by a solution of potash; its quantity either by measuring the diminution in bulk of the gas, or by noting the increase in weight of an alkaline solution. As the proportion of C0 2 in air is determinable readily and accurately, its determination in a confined air is depended upon to judge of the res- pirability of the air and the degree of perfection of the methods of ventilation used. For these purposes an air is condemned as vitiated if it contain more than six parts in 10,000 of C0 2 . ESTERS COMPOUND ETHERS. As the alcohols resemble the mineral bases, and the organic acids resemble those of mineral origin, so the esters are similar in constitu- tion to the salts, being formed by tlie double decomposition of an alco- hol with an acid, mineral or organic, as a salt is formed by double decomposition of an acid and a mineral base, the radical playing the part of an atom of corresponding valence: K' ) Q (NO,) ) H ) Q (N0 2 H f H f H f C K' Potassium hydroxide. Nitric acid. Water. Potassium nitrate. (C 2 H 5 )' ) (NO,) ) H ) (NO,) / Hf H f Hf 3Vr C Ethyl hydroxide Nitric acid. Water. Ethyl nitrate (alcohol). (nitric ether). Therefore the esters are substances derived from acids by par- tial or complete substitution of an alkyl or alkyls for the basic hydrogen of the acid. Some of the esters still contain a portion of the acid hydrogen which, being replaceable by another radical or by a metal, com- municates acid qualities to the substance, which is at the same time an ester and a true acid. Such esters are the counter-parts of the acid salts. Or di- and polyhydric alcohols, in combining with acids of inferior basicity, may form esters which still retain alcoholic hydroxyls, and which are, therefore, alcohol-esters. 276 TEXT-BOOK OF" CHEMISTRY ESTERS OF THE MONOHYDRIC ALCOHOLS. These esters are produced: (1) By the action of the acid upon the alcohol: H 2 S0 4 +CH 3 .CH 2 OH=CH 3 .CH 2 .HS0 4 +H 2 ; or H 2 S0 4 +2CH 3 .CH 2 OH= ( CH 3 .CH 2 ) 2 S0 4j +2H 2 (2) By the action of the corresponding haloid esters upon the silver salt of the acid: AgNO,+C 2 H B I=AgI+C 2 H B .N0 8 (3) By the action of the acidyl chlorides upon the sodium deriva- tives of the alcohols, and in some instances upon the alcohols them- selves : C 2 H 3 O.Cl+C 2 H 5 .O.Na=NaCl+C 2 H 3 2 .C 2 H 5 All esters are decomposed into acid and alcohols by the action of water at high temperatures, or of caustic potash or soda : ( C 2 H 5 ) N0 3 +KOH=KN0 3 +C 2 H 5 OH As this decomposition is analogous to that utilized in the manu- facture of soap (p. 282), it is known as saponification, and whenever an ester is so decomposed it is said to be saponified. When the de- composition is effected by H 2 the free acid and the alcohol are formed, and it is known as hydrolysis (p. 64) : ( C 2 H 5 ) C 2 H 3 2 +H 2 0=C 2 H 5 .OH+H.C 2 H 3 2 This reaction is reversible and therefore does not proceed to com- pletion. Starting with the ester it is saponified according to the equation until equilibrium is established, but starting with alcohol and acid the reaction proceeds according to the equation read from right to left until the same condition is reached. Ethyl Nitrate Nitric ether ^ | 91. A colorless liquid; has a sweet taste and bitter after-taste; sp. gr. 1.112 at 17; boils at 85 ; gives off explosive vapors. Prepared by distilling a mixture of HN0 3 and C 2 H 6 in the presence of urea. Ethyl Nitrite Nitrous ether J I 75 is prepared by di- recting nitrous fumes 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; gives off inflammable vapor; very sparingly soluble in H.,0; readily soluble in alcohol and ether. It is decomposed by warm H 2 and by alkalies. ESTERS COMPOUND ETHERS 277 Ethyl Sulphates (C 2 H 5 )IIS0 4 =^ Ethyl sulphuric or sulphovinic acid and (C 2 H 5 ) 2 S0 4 Ethyl -sulphate Sulphuric ether. Monoethylic sulphate Ethyl-sulphuric acid ^^'Q/ S0 2 is formed as an intermediate product in the manufacture of ethylic ether. It 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 with alcohol, it yields ethylic ether and H 2 S0 4 . When heated with H 2 0, it yields alcohol and H 2 S0 4 . It forms crys- talline salts, known as sulphovinates, or sulphethylates, one of which, sodium sulphovinate (C 2 H 5 )NaS0 4 , has been used in medi- cine. It is a white, deliquescent solid ; soluble in H 2 0. Ethyl Sulphate (C 2 H 5 ) 2 S0 4 the true sulphuric ether, is ob- tained by passing vapor of S0 3 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 decomposition. With H 2 it forms sulphovinic acid. Sulphurous and Hyposulphurous Esters. These compounds have recently assumed medical interest from their relationship to mer- captan, sulphonal and a number of aromatic derivatives used as medicines. There exist two isomeric sulphurous acids (p. 89), both of which yield neutral esters, but only one of which, the unsymmetrical O// S \OH' f rms ac id esters. These acid esters are known as sul- phonic acids. (See Aromatic sulphonic acids, mercaptan, sulphones, sulphonal.) Diethyl Sulphite (C 2 H 5 ) 2 S0 3 is produced by the action of thionyl chloride on absolute alcohol: SOC1 2 2C 2 H 5 OH=S0 3 ( C 2 H 5 ) 2 +2HCl. It is a colorless liquid, having a powerful odor : sp. gr. 1.085, boils at 161. H 2 decomposes it into alcohol and sulphurous acid. Ethyl Sulphonic Acid S0 2 ^^ 5 is formed by the action of ethyl iodide on potassium sulphite : C 2 H 5 I+S0 3 K 2 =C 2 H 5 .S0 2 OK+KI It forms salts and esters. Sulphinic Acids are the acid esters of hyposulphurous acid SOc^Qjj and are analogous to the sulphonic acids. Orthoformic esters are produced by heating chloroform with sodium ethylate or by adding sodium to a mixture of chloroform, ethyl alcohol and ether : CHCl 3 +3C 2 H 5 ONa=CH(OC 2 H 5 ) 3 +3NaCl They are colorless liquids used in certain syntheses. 278 TEXT-BOOK OF CHEMISTRY Ethyl Acetate Acetic ether c *?{ t O is obtained by distill- ing a mixture of sodium acetate, alcohol and H 2 S0 4 ; or by passing carbon dioxide through an alcoholic solution of potassium acetate : CH 3 .COOK+CH 3 .CH 2 OH+C0 2 =KHC0 3 +CH 3 .COO.C 2 H 5 It is a colorless liquid, has an agreeable, ethereal odor: boils at 74; sp. gr. 0.92 at 15 ; soluble in 6 pts. water, and in all proportions in methyl and ethyl alcohols and in ether ; a good solvent of essences, resins, cantharidin, morphine, gun cotton, and in general, of sub- stances soluble in ether ; burns with a yellowish-white flame. Chlorine acts energetically upon it, producing products of substitution, vary- ing according to the intensity of the light from C 4 H 6 C1 2 2 to C 4 C1 8 2 . Ethyl Aceto-acetate Aceto-acetic ester CH 3 .CO.CH 2 .COO- (C 2 H 5 ) is the most important representative of the class of y#-ketonic acid esters, which are important synthetic reagents. It is prepared by dissolving 6 pts. of metallic sodium in 200 pts. of anhydrous ethyl acetate, distilling off the excess of the ester, mixing the residue with 50 per cent, acetic acid in slight excess, decanting the oil which separates, and fractioning. The formation of aceto-acetic ester in this process occurs in several reactions, the sum of which may be expressed by the equation: 2CH 3 .COO(C 2 H 5 )=CH 3 .CO.CH 2 .COO(C 2 H 5 )+CH 3 .CH 2 OH two molecules of ethyl acetate forming one molecule of aceto- acetic ester and one of ethylic alcohol. In one stage of the reaction sodium acts upon ethyl acetate to form ethyl acetyl-sodacetate, sodium ethylate and hydrogen: 2CH 3 .COO(C 2 H 5 )+Na 2 =CH 3 .CO.CHNa.COO(C 2 H 5 ) + C 2 H 5 .O.Na+H 2 In another, sodium ethylate acts upon ethyl acetate to form ethyl acetyl-sodacetate and ethylic alcohol: 2CH 3 .COO ( C 2 H 5 ) +C 2 H 5 .O.Na=CH 3 .CO.CHNa.COO ( C 2 H 5 )* +2CH 3 .CH 2 OH and, when the operation is properly conducted, little or no hydrogen is evolved, because that produced in the above reaction acts with sodium upon ethyl acetate to form sodium ethylate : CH 3 .COO(C 2 H 5 )+Na 2 +H 2 =2C 2 H 5 .O.Na The aceto-acetic ester is liberated from its sodium derivative by acetic acid : CH 3 .CO.CHNa.COO(C 2 H 5 )+CH 3 .COOH=CH 3 .COONa +CH 3 .CO.CH 2 .COO ( C 2 H 5 ) Aceto-acetic ester is a colorless liquid, having a pleasant odor, b. p. 181, almost insoluble in water, and much more stable than the free acid. It is colored violet by FeCl 3 . ESTERS COMPOUND ETHERS 279 Malonic Ester Neutral ethyl malonate COO(C 2 H S ).CH 2 .COO(C 2 H 5 ) is obtained by the action of HC1 upon potassium cyano-acetate, or malonic acid, and alcohol: CH 2 CN.COOK+2CH,.CH 2 OH+HC1=KC1+NH,+COO ( C 2 H 5 ) .CH 2 .COO ( C 2 H 5 ) , or COOH.CH 2 .COOH+2CH,.CH,OH=C60 (C 2 H 5 ) .CH 2 COO ( C 2 H 5 ) +2H 2 It is a colorless liquid, b. p. 198, sp. gr. 1.07, insoluble in water and in alkaline solutions. When, as in the cases of aceto-acetic and malonic esters, an ester is referred to without designation of the contained alkyl, the neutral ethyl ester is always understood. Amyl Nitrate J^j? 2 1 obtained by distilling a mixture of HN0 3 and amylic alcohol in the presence of a small quantity of urea. It is a colorless, oily liquid; sp. gr. 0.994 at 10; boils at 148 with partial decomposition. Amyl Nitrite Amyl nitris (U. S. P.) c j*P j- 0117 prepared by directing nitrous fumes 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. Its vapor, which is orange-colored, explodes when heated to 260. It is insoluble in water; soluble in alcohol in all proportions. Alcoholic solution of potash decomposes it slowly, with formation of potassium nitrite and ethyl and amyl oxides. When dropped upon fused potash, it ignites and yields potassium valerianate. Cetyl Palmitate Cetin C g H g | 0480 is the chief constit- uent of spermacetfccetaceum (U. S. P.), which, besides cetin, con- tains esters of palmitic, stearic, myristic, and laurostearic acids; and of the alcohols: lethol, C 12 H 26 ; methol, C 14 H 30 0; ethol, C 16 H 34 0, and stethol, C 18 H 38 0. ESTERS OF DIHYDRIC ALCOHOLS OR GLYCOLS. The glycols behave as diacid bases and form with the monobasic acids basic and also neutral esters: CH 2 OH CH 2 .OOC.CH 8 CH 2 OOC.CH 8 CH 2 OH CH.OH CHa.OOC.CHs Glycol. Glycol mono-acetate. Glycol diacetate. The haloid esters of the glycols are also basic or neutral. The basic com- pounds are the glycol halohydrines, e.g., CH 2 OH.CH 2 Cl=:Ethylene chlor- hydrine, produced by the action of the hydracids upon the glycols, or upon ethylene oxide and its homologues The neutral haloid esters are among the haloid derivatives of the paraffins, higher than the first. They are produced by ( 1 ) substitution of the halogen in the paraffin or in the monohalogen paraffin ; thus ethyl chloride : CH 3 .CH 2 C1 yields 280 TEXT-BOOK OF CHEMISTRY ethylene chloride; CH 2 C1.CH 2 C1; (2) by addition of the halogens to the olefines, thus ethylene: CH 2 : CH 2 yields ethylene bichloride; CH 2 C1.CH,C1; (3) by the action of the hydracids upon the raonohalogen olefines, or upon the glycols, or upon the glycol chlorhydrines. Thus ethylene bichloride is obtained from ethylene monochloride : CHC1:CH 2 ; ethylene glycol: CH a OH.CH 2 OH; or ethy- lene chlorhydrine: CH 2 OH.CH 2 C1. By this latter method two isomeres: CHC1 2 .CH 3 and CH 2 C1.CH.C1 may be produced. The neutral haloid esters of the glycols are the starting points in the preparation of the glycols: CH 2 Br.CH 2 Br+2AgOH^2AgBr+CH 2 OH.CH 2 OH Nascent hydrogen converts them into the paraffins: CH 2 C1.CH 2 C1+2H 2 =2HC1+CH 3 .CH 3 Ethylene Chloride Elayl chloride Dutch liquid CH 2 C1.CH 2 C1 is ob- tained by passing ethylene through a retort in which chlorine is generated. It is a colorless, oily liquid, has a sweetish taste and an ethereal odor; boils at 84. It is capable of fixing other atoms of chlorine by substitution to form a series of compounds, the most highly chlorinated of which is carbon tri- chloride, C 2 C1 6 . ESTERS OF THE TRIHYDRIC ALCOHOLS OR GLYCEROLS GLYCERIDES. The glycerols behave as triacid bases, forming three series of esters with the monobasic acids. These esters are the mono-, di-, and triglycerides. Moreover, as two of the hydroxyls of the alcohol are in the primary groups CH 2 OH, while the third is in the secondary group, CHOH, there are two isomeres of each mono- and diglyceride : CH 2 .C 2 H 8 2 CH 2 OH CH 2 .C 2 H,O 2 CH 2 .C 2 H 3 0, CH 2 .C 2 H 3 2 CHOH CH.C 2 H 3 O 2 CHOH CH.C 2 H 3 2 CH.C 2 H 8 O a CH 2 OH CH 2 .OH CH 2 .C 2 H,0 2 CH 2 OH CH 2 .C 2 H 8 O 2 a-Monacetin. p Monacetin. a-Diacetin. /3-DIacetin. Triacetin. The haloid esters are known as the glycerol halohydrines. Of the glycerol esters of mineral oxyacids those of nitric and phosphoric acids are of interest. Glycerol trinitrate Trinitroglycerol Nitroglycerin Glonoin C 3 H 5 (NO 3 ) 3 is formed by the action of a mixture of H 2 S0 4 and HN0 3 upon glycerol: C 3 H 5 (OH) 3 +3HN0 3 =3H 2 0+C 3 H 5 (N0 3 ) 3 It is an odorless, yellowish oil; has a sweetish taste; sp. gr. 1.6; crystallizes in prismatic needles when kept for some time at 0; fuses again at 8. When suddenly heated, or when subjected to shock it is explosively decomposed into C0 2 ;N ;H 2 and 0. Alkalies saponify it to glycerol and a nitrate. Nitroglycerol is mixed with diatomaceous earth and with other inert, absorbent substances in dynamite and in other high explosives ; and, combined with nitrocellulose, it forms "smokeless powder." ESTERS COMPOUND ETHERS 281 It is used in medicine as a cardiac stimulant, and, in overdose, is an active poison, producing effects somewhat similar to those caused by strychnine. Spirit of glyceryl trinitrate, spirit of glonoin spiritus glycerylis nitratis (U. S. P.), is an alcoholic solution of trinitroglycerol, con- taining 1 per cent. Glycero-phosphoric Acid C 3 H 5 (OH) 2 .O.P0 3 H 2 is the mono- glyceride of phosphoric acid. It is a product of decomposition of the lecithins, or phosphorized fats or may be formed by mixing glycerol and metaphosphoric acid: C 3 H 5 ( OH) 3 +HP0 3 =C 3 H 5 ( OH) 2 O.P0 3 H 2 It is a thick syrup, which is decomposed into glycerol and phos- phoric acid when heated with water. It is a dibasic acid. The lithium, sodium, potassium, calcium and iron salts of this acid are occasionally used in medicine. Glycerol Esters of Organic Acids. The triacid glycerol esters of the acids of the acetic and acrylic series containing an even num- ber of carbon atoms occur in the animal and vegetable fats and oils. Tributyrin C 3 H 5 (O.C 4 H 7 0) 3 302 exists in butter. It may also be obtained by heating glycerol with butyric acid and H 2 S0 4 . It is a pungent liquid, very prone to decomposition, with liberation of butyric acid. Tricaproin C 3 H 5 (O.C a H 11 0) s --386 Tricaprylin C 3 H 5 (O.C 8 - H 15 0) 3 470 and Tricaprin C 3 H 5 (O.C 10 H 19 0) 3 554 exist in small quantities in milk, butter, and cocoa butter. Tripalmitin C 3 H 5 (O.C lfi H 31 0) 3 806 exists in most animal and vegetable fats, notably in palm oil. It may also be obtained by heat- ing glycerol with 8 to 10 times its weight of palmitic acid for 8 hours at 250. It forms crystalline plates, very sparingly soluble in alco- hol, even when boiling; very soluble in ether. It fuses at 50, and solidifies again at 46. Trimargarin C 3 H 5 (O.C 17 H 33 0) 3 848 has probably been ob- tained artificially as a crystalline solid, fusible at 60, solidifiable at 52. The substance formerly described under this name as a con- stituent of animal fats is a mixture of tripalmitin and tristearin. Tristearin C 3 H 5 (O.C 18 H 35 0) 3 890 is the most abundant con- stituent of the solid fatty substances. It is prepared in large quantities as an industrial product in the manufacture of stearin candles, etc., but is obtained free from tripalmitin only with great difficulty. In as pure a form as readily obtainable, it forms a hard, brittle, crystalline mass ; fusible at 68 , solidifiable at 61 ; soluble in boiling alcohol, almost insoluble in cold alcohol, readily soluble in ether. . Triolein C 3 H 5 (O.C 18 H 33 0) 3 884 exists in varying quantity in all fats, and is the predominant constituent of those which are liquid 282 TEXT-BOOK OP CHEMISTRY at ordinary temperatures. It may be obtained from animal fats by boiling with alcohol, filtering the solution, decanting after twenty- four hours' standing; freezing at 0, and expressing. It is a colorless, odorless, tasteless oil ; soluble in alcohol and ether, insoluble in water; sp. gr. 0.92. The Neutral Oils and Fats are mixtures in varying proportions of the triglycerides of the acids of the acetic and acrylic series, principally tripalmitin, tristearin, and triolein The first two of these are solid at the ordinary tem- perature and the las*, liquid. In the oils the last predominates, in the fats the former. In the cold the oils become solid (fats), and, on heating, the fats become oils. The fats and oils are usually odorless, white or yellow, unctuous to the touch, and produce a translucent stain upon paper. They are insoluble in and lighter than water, readily soluble in ether, petroleum ether, benzene, and many other organic solvents. Although the oils do not mix with water, and promptly rise to its surface after having been agitated with it, an oil may remain suspended for a long time; suspended in very minute globules in an aqueous liquid, if bile, pancreatin, albumin, or other emulsifying agents be present. Such a mixture, sometimes practically per- manent, is called an emulsion. Like other esters the fats and oils are hydrolyzed or saponified when heated with steam or with a caustic alkali. The alcohol, glycerol, is liberated, and, if steam is used, the fatty acid also; while if an alkali is used a soap is formed, which is a salt of the fatty acid: C 8 H 8 (C 18 H 83 2 ), + 3KOH = C 3 H 8 (OH), -f- Glyceryl oleate Glycerol. Potassium oleate (Pat) (Soap) The sodium soaps are hard, those of potassium soft. Castile soap is a sodium soap, made from olive oil. Yellow soap is made from tallow or other animal fat, and contains about one-third of its weight of rosin. Lead plaster is lead soap. The fixed oils are so called to distinguish them from the volatile oils, more properly called essences, which are also unctuous to the touch, and render paper translucent, but which are hydrocarbons, not esters. The vegetable oils form three classes: (1) The non-drying, or greasy oils, which remain liquid and greasy on exposure to air. Olive oil and peanut oil are representatives of this class. (2) Drying oils, which dry and become hard when exposed to air. These oils, which contain linoleic acid, are used in making paints. Linseed, hemp, poppy, and sunflower oils are drying oils. (3) Semi- drying oils are intermediate between the other two classes, and are more or less drying. In this class are cottonseed, sesame, rape seed, and castor oils. The animal oils, used for dressing leather, as lubricants and for illumination, are fish oils, whale, and porpoise oil, neat's foot oil, lard oil, and tallow oil. Cod liver oil contains, besides the glycerides. of oleic, myristic, palmitic, and stearic acids, small quantities of those of butyric and acetic acids. It also contains certain biliary principles, a phosphorized fat, traces of iodine and bromine, probably in organic combination, a peculiar fatty acid called gadinic acid, a brown substance called gadinin, and two alkaloidal bodies: aselline, C 26 H 82 N 4 , and morrhuine, Ci e H 27 N 3 . Sperm oil is not a true oil, but a liquid wax; it contains no glycerides, but consists mainly of esters of the higher monoatomic alcohols. Lecithins Phosphorized Fats. These substances are widely distributed in animal and vegetable tissues and fluids, and are par- ESTERS COMPOUND ETHERS 283 ticularly abundant in the yolks of eggs, brain, and nerve tissue, semen, and blood-corpuscles and plasma, where they probably serve as material for the formation of the more complex phosphorized bodies such as protagon and the nucleins. The lecithins are colorless or yellowish, imperfectly crystalline solids, of a waxy consistency, and very hygroscopic. They do not dissolve in water, but swell up in it like starch. They are soluble in chloroform, in benzene, and in hot alcohol and hot ether. From alcoholic solutions they crystallize in fine needles. When heated with baryta water or with acids they are decomposed into glycero-phosphoric acid, chlorine, and a fatty acid, usually palmitic or stearic. The lecithins are therefore deriva- tives of glycero-phosphoric acid, in which the two remaining hy- droxyls of the glycerol are replaced by fatty acid residues, and one of the two remaining basic hydrogen atoms of the phosphoric acid is replaced by the basic radical of choline, which is a quaternary ammonium : /O.N.CH 2 .CH 2 .OH 0:P OH \O.CH 2 .CH(C 18 H3 B 3 ).CH 2 (C lfl H 81 2 ) Stearyl-palmityl lecithin. From the above formula it will be seen that the lecithins may unite with acids, through the remaining OH of the choline, or with bases, through the remaining basic H of the phosphoric acid, to form salts. The lecithins differ from each other in the nature of the fatty acids entering into their composition. Distearyl-, dioleyl- and stearyl-palmityl lecithins are known. ESTERS OF OXYACIDS LACTIDES AND LACTONES. The oxyacids not only form esters with the alcohols in the same manner as the pure acids, but, being themselves both alcohol and acid, they produce cyclic esters, in the formation of which they play the part of alcohol as well as that of acid. The lactides are formed by the interaction of two oxyacid molecules, each performing the functions of both alcohol and acid. The lactones, which are formed only by the y and higher oxyacids, are produced from a single molecule of the acid, whose carboxyl and alcoholic groups interact with each other. The following formulae will indicate the genesis of the lactides and lactones: CH 2 OH COOH COOH CEUOH Glycollic acid. CH 2 .COO COOH ccxr COO.CH 2 aCH 2 aCH 2 0CH 2 j8CH 2 yCH 2 OH yCH 2 . GlycolHde y -Oxybutyric V -Butyrolactone (Lactide). acid. (Lactone.) 284 TEXT-BOOK OF CHEMISTRY The y lactones are formed from the y monohalogen acids: (1) by dis- tillation: COOH.CH 2 .CH 2 .CH 2 C1=COO.CH 2 .CH 2 .CH 2 -|-HC1 (2) By boiling with H 2 0, KOH or K 2 CO 3 : COOH.CH 2 .CH 2 .CH 2 Cl T f-KOH=H 2 0+KCl+COO.CH 2 .CH 2 .CH 2 By reduction the higher lactones yield aldo-hexoses. Thus d-glucose is produced by the reduction of the lactone of d-gluconic acid: COO. ( CHOH ) 4 .CH 2 +H,=CHO. ( CHOI! ) .CH 2 OH The higher oxycarboxylic acids readily lose water arid are converted into lactones. Acylation Determination of Hydroxyl, etc. The formation of esters by the introduction of acidyls, referred to as acylation, is utilized to determine the number of alcoholic or phenolic hydroxyls contained in a molecule. The acidyls usually resorted to for this purpose are acetyl, CH 3 .CO, and benzoyl, C 6 H 5 .CO; and the reactions most frequently employed are those between the substance examined and the oxide or chloride of the acidyl. Thus phencl and acetyl chloride produce phenyl acetate: C fl H 5 .OH+CH,.COCl=C 9 H 5 .O.OC.CH 8 +HCl And methyl alcohol and benzoyl chloride produce methyl benzoate: H.CH 2 OH+C ft H 5 .COCl=C a H B .COO ( CH 3 ) +HC1. The process of alkylation, i.e., the replacement of H in OH by alkyls to form esters, has more limited application. Alkyls may replace the H of OH in carboxyl COOH, in the methoxyl group of the primary alcohols, CH 2 OH, and in the phenolic hydroxyl, C 8 H V OH, but not in the secondary and tertiary alcoholic groups CHOH and COH. Therefore, alkylation may sometimes be resorted to to differentiate the latter hydroxyls from the former. SULPHUR DERIVATIVES OF THE PARAFFINS. As the mineral sulphides and sulphydrates correspond to the oxides and hydroxides, so there exist thioethers and thioalcohols, which are the counterparts of the simple ethers and of the alcohols, as well as thioaldehydes, thioketones and thioacids. Moreover, as sulphur may be quadrivalent or hexavalent, as well as bivalent, there exist other important compounds, the sulphoxides, sulphones and sulphonic acids, which have no oxygen analogues. The following formulae will serve to illustrate the relations of the oxygen and thio compounds: CH 2 OH /CH 2 .CH, COOH /O.CH 2 .CH. O CH 8 .CH CH, \CH 2 .CH, CH S \O.CH 2 .CH, Ethyllc alcohol. Ethyl oxide. Acetic acid. Acetal. CH 2 SH /CH 2 .CH, COSH /S.CH 2 .CH, S CH..CH CH, \CH,.CH, CH, \S.CH 2 .CH, Ethyllc thloalcohol. Ethyl sulphide. Thloacetlc acid. Mercaptal. Thioethers, or Sulphides are produced by processes correspond- SULPHUR DERIVATIVES OF THE PARAFFINS 285 ing to those by which the ethers are formed : (1) by distilling salts of ethyl-sulphuric acids with potassium sulphide: 2KS0 4 .C 2 H 5 +K 2 S=S(C 2 H 5 ) 2 +2K 2 S0 4 (2) By the action of alkyl halides upon potassium sulphide: 2CH 3 C1+K 2 S=S(CH 3 ) 2 +2KC1 (3) By the action of phosphorus pentasulphide upon the oxygen ethers : 40(C 2 H 5 ) 2 +P 2 S 5 =S(C 2 H 5 ) 2 +2(C 2 H 5 ) 3 P0 2 S 2 The last is a general method by which the thio compounds may be obtained from the corresponding oxygen compounds, the sec- ondary products being thiophosphoric esters. The thioethers are colorless liquids, insoluble in water, soluble in alcohol and ether, of disagreeable odors. They contrast with the oxygen ethers chiefly in their additive power, dependent upon the greater valence capacity of sulphur. Thioalcohols Mercaptans are formed: (1) by the action of po- tassium sulphydrate upon alkyl halides : KHS+CH 3 .CH 2 C1=CH 3 .CH 2 SH+KC1 (2) By distilling the salts of the acid alkyl sulphates with po- tassium sulphydrate: KS0 4 (C 2 H 5 ) +KHS=CH 3 .CH 2 SH+K 2 S0 4 ; and (3) By the action of phosphorus pentasulphide upon the alcohol. The thioalcohols differ in some of their general reactions from the alcohols : While the H of the OH of alcohols can only be replaced by K and Na among the metals, the H and SH may be replaced by the heavy metals as well. Thus with mercuric oxide : 2CH 3 .CH 2 SH+HgO=r(CH 3 .CH 2 S) 2 Hg+H 2 Such metallic compounds are called mercaptids, and the name "mercaptan" (mer curium captans), is due to the formation of mer- cury mercaptid. Owing to the greater valence capacity of sulphur, the thioalcohols do not yield thioaldehydes and thioacids on oxidation. Ethyl mercaptan Ethyl sulphydrate Thioalcohol CH 3 .CH 2 - SH is prepared industrially, as the first step in the formation of sulphonal, by the first of the general methods given above. It is a colorless liquid, sp. gr. 0.8325, boils at 36.2, has an intensely disagreeable odor, burns with a blue flame, is neutral in reaction, sparingly soluble in water, soluble in alcohol and in ether, dissolves I, S and P. Potassium and sodium act upon mercaptan as they do upon alcohol, replacing the extra-radical hydrogen to produce mercaptids, or thioethylates, corresponding to the ethylates. There also exist mono- and di-thioglycols, corresponding to the 286 TEXT-BOOK OF CHEMISTRY dihydric alcohols. One of these, monothioethylene glycol C 2 H 4 .- OH.SH, yields isethionic acid on oxidation. Sulphoxides and Sulphones are products of oxidation of the sulphides in which the sulphur is quadrivalent or hexavalent : C 2 H 6 \ o C 2 H 6 \ s _ C 2 H 5 \ // o C 8 H 5 / b C 2 H 5 / b C ? H 8 / S \\0 Ethyl sulphide. Ethyl sulphoxlde. Etbyl sulphone. Other products of oxidation of thio-compounds, containing the group (S0 2 )" attached to a hydrocarbon group, are also called sulphones. Sulphonic Acids are acids containing the group (0 2 S.OH)' at- tached to a hydrocarbon group. The sulphonic acids of this series are formed by oxidation of the mercaptans; by the action of the paraffin iodides upon the alkaline sulphites or Ag sulphite ; or by the action of sulphuric acids upon alcohols, ethers, etc. They may be considered as being derived from the unsymmetrical sulphurous acid (p. 89) by replacement of the H atom by an alkyl; and are isomeric with the monoalkyl sulphites (formula below), from which they are distinguished by the fact that the latter, being esters, are saponified by alkalies, which the former are not. The thioglycols on oxidation also yield sulphonic acids. Isethionic acid, C 2 H 4 .OH.S0 3 H, mentioned above, is a thick liquid, whose amido derivative is taurin. In the thiosulphonic acids, which only exist in their salts and esters, the oxygen in the hydroxyl of the sulphonic acids is replaced by sulphur. Sulphinic acids bear the same relation to hydrosulphurous acid that the sulphonic acids do to the unsymmetrical sulphurous acid : 0\\ /H 0\\ o /C 2 H, _ s /O.C 2 H 6 _ s /H _ s /C 2 H 6 0// S \OH O// b \OH b \OH b \OH b \OH Unsymmetrlcal Etbyl sulphonic Monethyllc Hydrosulphurous Etbyl sulphinic sulphurous acid. acid. sulphite. acid. acid. Thioaldehydes and their Sulphones. The simple thioaldehydes are not known, owing to the tendency to polymerize which they pos- sess to a still more marked degree than the aldehydes (p. 228). The trithioaldehydes and their sulphones are odorless, colorless solids. The relations of these compounds are shown by the f ormulaB : f\ p /H o p /H >-x/CH 2 .0\ p-p- Q /CH 2 .S\ p.p. _. ~/ CH 2 .S0 2 \pTT ~ C \H ~ C \H \CH 2 .0/ CH ' b \CH 2 .S/ CHj ' b \CH 2 .S0 2 / tH ' Formic Thloformic Triform- Trlthloform- Trlmethylene aldehyde. aldehyde. aldehyde. aldehyde. trlsulphone. Thioacetals Mercaptals are produced by the action of paraffin iodides upon alkali mercaptids, or by the action of HC1 upon a mix- SULPHUR DERIVATIVES OF THE PARAFFINS 287 ture of aldehyde and mercaptan. By oxidation they yield sulphones, whose,, methylene hydrogen may be replaced by alkyl groups : H\ r /O.C 2 H 5 H\ r /S.C 2 H 5 H\ p /S0 2 .C 2 H 5 H\ r /S0 2 .C 2 H 5 H/ C \O.C 2 H 5 H/\S.C 2 H 5 H/ C \S0 2 .C 2 H 5 CH 3 / u \S0 2 .C 2 H 5 Metbylene diethyl ether Methylene Methylene diethyl Ethldene diethyl (Acetal). rnercaptal. sulphone. sulphone. Sulphonal Acetone Diethyl Sulphone Disulphethyl-dimefhyl- methane (CH 3 ) 2 :C(S0 2 C 2 H 5 ) 2 is obtained by oxidizing ethyl mercaptol by potassium permanganate. It crystallizes in thick, color- less prisms, difficultly soluble in cold water or alcohol, readily soluble in hot water or alcohol, and in ether, benzene and chloroform. It fuses at 126 and boils at 300 , suffering partial decomposition. Sulphonal contains two ethyl groups, trional contains three, and tetronal four. Their hypnotic power increases with the number of ethyl groups which they contain. Other ' ' sulphonals " are obtain- able from the corresponding mercaptols by methods similar to the above. Among these is acetone dimethyl sulphone, which contains no ethyl group, and has no hypnotic action. The relations of these compounds is shown by the following formulae : CH,\ p /S0 2 .C 2 H 6 CH 3 \ /S0 2 .C 2 H B C 2 H 5 \ /S0 2 .C 2 H 5 CH 3 \ r /S0 2 .CH 8 CH 8 / L \S0 2 .C 2 H 5 C 2 H 5 / U \S0 2 .C 2 H 5 C 2 H 5 / c \SO 2 .C 2 H e CH 8 / L \S0 2 .CH, Sulphonal. Trional. Tetronal. Acetone dimethyl sulphone. Ichthyol is the Na salt of a complex sulphonic acid, having the empirical formula C 28 H 36 S 3 6 Na 2 , obtained by the distillation and purification of an ozocerite (a mineral pitch). It is a dark brown, pitchlike mass, having a disagreeable odor, soluble in water and in glycerol. Thioacids and their Thioanhydrides. In the thioacids of the acetic series the sulphur is substituted for the oxygen in the hydroxyl. Thioacetic acid, CH 3 .CO.SH, is formed by the action of phosphorus pentasulphide upon acetic acid. Carbon Bisulphide CS 2 bears the same relation to sulphothio- carbonic acid, CS\Q H , and to trithiocarbonic acrd, CS\|g, that car- bon dioxide bears to carbonic acid. It is prepared by passing vapor of S over C heated to redness, is partly purified by rectification, and obtained pure by redistillation over mercuric chloride. It is a colorless liquid. When pure it has a peculiar, but not disagreeable odor, the nauseating odor of the commercial product being due to the presence of another sulphurated body ; boils at 47 ; sp. gr. 1.293 ; very volatile. Its rapid evaporation in vacuo produces a cold of 60. It does not mix with H 2 0. It refracts light strongly. It is highly inflammable, and burns with a bluish flame, giving off C0 2 and S0 2 ; its vapor forms highly explosive mixtures with air, 288 TEXT-BOOK OF CHEMISTRY which detonate on contact with a glass rod heated to 250. Its vapor forms a mixture with nitrogen dioxide, which when ignited, burns with a brilliant flame, rich in actinic rays. A substance also exists, intermediate in composition between C0 2 and CS 2 , known as carbon oxysulphide, CSO, which is an inflam- mable, colorless gas, obtained by decomposing potassium thiocyanate with dilute H 2 S0 4 . Toxicology. Workmen engaged in the manufacture of CS 2 , and in the vul- canization of rubber, as well as others exposed to the vapor of the disulphide, are subject 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 disagreeable taste, and cramps in the legs. The patient talks, laughs, sings, and weeps im- moderately, and sometimes becomes violently delirious. In the second stage the patient becomes sad and sleepy, sensibility diminishes, sometimes to the extent of complete anesthesia, 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 workshop, and abandonment of the trade at the first appearance of the symptoms. ORGANO-METALLIC COMPOUNDS. These are compounds of organic radicals with metallic elements, the best known being those of the alkyls with zinc and mercury. Zinc-methyl, or Zinc Methide (CH 3 ) 2 Zn, and Zinc-ethyl, or Zinc Ethide (C 2 H 5 ) 2 Zn are formed by heating to 130-150 methyl or ethyl iodide with excess of zinc amalgam, and distilling without contact of air. They are colorless liquids, the former b. p. 46, sp. gr. 1.386, the latter b. p. 118, sp. gr. 1.182. On contact of air they ignite and burn, giving off dense clouds of ZnO. By the moderated action of air they produce solid oxyalkylates : or alcoholates: Zn/J S 3 . The former are also produced, along with \ v/.V_/l 3 hydrocarbons, by the action of zinc-alkyls upon alcohols: (CH 3 ) 2 Zn+H.CH 2 OH^CH 3 .O.Zn.CH 3 +CH 4 and are decomposed by water with formation of hydrocarbons and primary alcohols: CH 3 .O.Zn.CH 3 +2H 2 0=ZnH 2 2 +H.CH 2 OH+CH 4 With the halogens the zinc alkyls react violently to form alkyl halides : (CH 3 ) 2 Zn+2Br 2 =2CH 3 Br+ZnBr 2 They unite with sulphur dioxide to produce zinc alkyl-sulphinates (p. 286) : (C 2 H 5 ) 2 Zn+S0 2 = (0 :S ) 2 Zn With acidyl chlorides and aldehydes they form complex com- ORGANO-METALLIC COMPOUNDS 289 pounds, Vhich are decomposed by water to form ketones, or tertiary or secondary alcohols. Zinc alkyls act with acidyl chlorides to form addition products: /CH 3 CH 3 .CO.Cl+Zn(CH 3 ) 2 =CH 3 .C O.Zn.CH 3 \C1 which are decomposed by H 2 with formation of ketones and hydro- carbons : /CH 3 CH 3 .C O.Zn.CH s +H 2 0=CH 3 .CO.CH s +Cl.Zn.OH+CH 4 \C1 or in which the Cl atom may be replaced by an alkyl by the action of a second molecule of the zinc alkyl: /CH 3 /CH 3 CH 3 .C O.Zn.CH 3 +Zn.(CH 3 ) 2 =CH 3 .C O.Zn.CH 3 +Cl.Zn.CH 3 \C1 \CH 3 and this compound on decomposition by H 2 yields a tertiary alco- hol and a hydrocarbon : /CH 3 /CH 3 CH 3 .C O.Zn.CH 3 +2H 2 0=CH 8 .C OH+Zn(OH) 2 +CH 4 \CH 3 \CH 3 By its action upon aldehydes the zinc alkyl forms addition products similar to those produced with the acidyl halides, the halogen being, however, replaced by H : /CH 3 CH 3 .CHO+Zn(CH 3 ) 2 =CH 3 .C O.Zn.CH 3 \H which on decomposition by water yields secondary alcohols : /CH 8 /CH 8 CH 3 .C O.Zn.CH 3 +H 2 0=CH 3 .C. OH+HO.Zn.CH 3 \H \H Carbonyl chloride reacts with the zinc alkyl to form acidyl chlorides: 2COCl 2 +Zn(CH 3 ) 2 =2CH 3 .CO.Cl+ZnCl 2 which with water produces the corresponding acids: CH 3 .CO.C1+H 2 0=CH 3 .CO.OH+HC1 Organo-Magnesium Compounds. Compounds corresponding to the zinc alkyls : R 2 Mg are known, and are equally unstable and diffi- cult to handle. The mixed organo-halide compounds of Grignard of the type R.Mg.X, in which R is a univalent hydrocarbon radical, aliphatic or cyclic, and X a halogen, are more convenient to handle and give better results in the syntheses of hydrocarbons, alcohols and monobasic acids (pp. 203, 212, 251). Magnesium turnings in the presence of anhydrous ether react with alkyl bromides and iodides to form gray semi-crystalline compounds which are etherates of alkyl magnesium halides, "oxonium" compounds, in which the R\ /x oxygen is quadrivalent and basic, of the type , in which R / \MgR' 290 TEXT-BOOK OF CHEMISTRY K. R. are the alkyls of the ether, R' that of the alkyl halide, and X the halogen. These in turn are decomposed with the formation of alkyl magnesium halides of the type: R.Mg.X. Or the reaction R\ /R' R\ /R' may take place in two stages: R'X+R 2 0= , and R/ \X R/ \X -f Mg=R'.Mg.X-|-R 2 0, the ether behaving as a catalyser. The re- action does not occur in the simple form: R'X-f-Mg=R'.Mg.X, as it does not occur in the absence of ether, as when benzene, petroleum ether, etc. are used as solvents. Carbonyl chloride and alkyl magnesium halides interact to pro- duce tertiary alcohols: COCl 2 +3CH 3 .MgCl=(CH 3 ) 3 :C.O.MgCl+2MgCl 2 , and ( CH 3 ) 3 !C.O.MgCl+H 2 0= ( CH S ) a :COH+HO.MgCl Water and compounds containing hydroxyls, such as alcohols, acids, phenols, etc., decompose the organo-halide magnesium compounds with formation of the corresponding hydrocarbons, according to the equations : R.Mg.X+H 2 0=RH+MgO+HX, or R.Mg.X+R.CH 2 OH=R.CH 3 +R.O.MgX, or R.Mg.X+R.COOH=:RH+R.COO.Mg.X, or R.MgX+C 6 H 5 .OH=C 6 H 5 .H.+R.O.Mg.X The compounds R.O.Mg.X and R.COO.Mg.X are themselves hydro- lyzed by water with regeneration of the corresponding alcohol or acid: R.O.Mg.X+H 2 0=R.OH+HO.Mg.X, and R.COO.Mg.X+H 2 0=R.COOH+HO.Mg.X The alkyl magnesium compounds act upon substances, such as alde- hydes and ketones, containing an oxygen atom doubly linked to carbon, to form condensation products of the types R.O.Mg.X or R.CH. R.O.Mg.X. These condensed compounds are readily hydro- lyzed by dilute acids to magnesium hydrohalides, and a hydroxyl is attached to the carbon in the position of the oxygen linkage. The above, known as the Grignard reactions, are extensively used in the preparation of alcohols, both aliphatic and cyclic. The reaction with formic aldehyde differs from that with its superior homologues. The phenyl magnesium halides are readily oxidized by the passage of air through their ethereal solutions with formation of condensed com- pounds of the type R.O.Mg.X which when hydrated yield phenols. The organo-magnesium halides react with esters of monobasic acids, except formic, with the formation of condensed products which on hydrolysis produce tertiary alcohols: 2R'.Mg.X+R.COO(C 2 H 5 )=:R.C \ gX +C 2 H 5 .O.Mg.X, and R.C. {;f gX +H 2 0= , COH+HO.Mg.X NITROGEN DERIVATIVES OF THE PARAFFINS 291 Ethyl formate under like conditions yields a secondary alcohol: 2R.Mg.X+H.COO(C 2 H 5 )=R.CH < MgX +C 2 H 5 .O.Mg.X, and R.CH \R Mg C.CH 2 .C /gf +2HO.Mg.X By passing C0 2 through solutions of the alkyl magnesium halides, compounds of the type R.COO.MgX are precipitated, which when hydrolyzed at low temperatures produce monobasic acids (p. 251). But with phenyl magnesium halides, the principal final products are alcohols. The reactions between acidyl chlorides or anhydrides and alkyl magnesium halides are violent. When moderated by ice they result in the formation of tertiary alcohols (p. 213). The organo-magnesium halides condense with nitriles according to the equation : R.Mg.X+R'.CN=RR' :C :N.Mg.X and the products produce ketones by hydrolysis: R.R' :C :N.Mg.X+2H 2 0=R.CO.R'+NH 3 +HO.Mg.X But .with isonitriles condensed products are formed : R.Mg.X+R'.N^C=R'.N=:C <^* x which when hydrolyzed produce imines: R/N :C /Mg- x +H 2 0=R'.N :CH.R+HO.Mg.X Alkyl magnesium halides act upon amides to produce aldehydes or ketones (pp. 227, 234). Grignard's compounds react with ammonia, amines (including aniline) and phenyl hydrazine with the formation of a hydrocarbon and of compounds of the types: H 2 N.Mg.X; R.HN.Mg.X; R.R'.N.Mg.X; C 6 H 5 .N(MgX).NH(MgX), which are known as Meunier's compounds. NITROGEN DERIVATIVES OF THE PARAFFINS. Speaking strictly, the only nitrogen derivatives of the paraffins are the nitriles, derived from the paraffins by substitution of N for H 3 , as CH 3 .CN, from CH 3 .CH 3 and the diazo paraffins, (N 2 )"CH.CH 3 , 292 TEXT-BOOK OF CHEMISTRY but the compounds derivable from the paraffins and from their oxida- tion products by substitution of nitrogen containing groups, N0 2 , NO, NH 2 , NH, NOH, - -N:N , and =N.N=, are numerous, varied and important. NITROPARAFFINS. The univalent group (N0 2 ) is designated by the syllable nitro in the names of compounds containing it. The mononitroparaffins isomeric with the nitrous esters are de- rived from the paraffins by the substitution of N0 2 for an atom of hydrogen, and are distinguished as primary, secondary and tertiary, in the same manner as the corresponding alcohols, according as the N0 2 is united to CH 2 (CH 3 in nitromethane), or CH, or C. They are formed by the action of the alkyl iodides upon silver nitrite : CH 3 I+AgN0 2 =AgI+CH 3 N0 2 They are isomeric with the nitrous esters: CH 3 .CH 2 .N(( o =mono- nitroethane, and CH 3 .CH 2 .ON :0=Ethyl nitrite. These isomeres may be distinguished by the action of KOH, which saponifies the esters: C 2 H 5 ON :0+KOH=KON :0-fCH 3 .CH 2 OH but has no action upon the nitroparaffins. Nascent hydrogen converts them first into hydroxylamine com- pounds: CH 3 .N0 2 +2H 2 =CH 3 .NH.OH-fH 2 0, which are in turn further reduced to monamines, or amidoparaffins : CH 3 .NH.OH+H 2 =NH 2 .CH 3 +H 2 AMINES AND AMMONIUM DERIVATIVES. The amines are compounds derived from ammonia by the substi- tution of hydrocarbon (non-acid) radicals for a part or all of its hydrogen. They are classified into monamines, derived from a single mole- cule of ammonia, diamines, derived from two such molecules, and triamines, derived from three. MONAMINES AND THEIR DERIVATIVES. The monamines are primary, secondary, or tertiary, as one, two, or three of the hydrogen atoms of ammonia have been replaced. They are also distinguished as amine, imine, and nitrile bases. When, in secondary or tertiary amines, the substituted radicals are alike the amines are designated as simple, when the radicals are different the amines are mixed. The primary monamines, containing the group NH 2 , an- amido-paraffins ; while the secondary, containing the group AMINES AND AMMONIUM DERIVATIVES 293 NH, are imido-paraffins. The monamines have the algebraic for- mula, NCfiHsw-hs A nomenclature similar to the above is also used in speaking of nitrogen in other, more complex, organic compounds. It is said to be in primary combination, or as amide, or amine nitrogen, when in the amido, or amino group (NH 2 )', in secondary combination, or as imide, or imine nitrogen, when in the imido, or imine, group (NH)", and in tertiary combination, or as nitrile nitrogen, when in the form N"'. Azo-, diazo-, and hydrazo- nitrogen is in the forms N:N and =N.N=. The monamines are sometimes called compound ammonias, from their resemblance to ammonia in their chemical properties, as well as from their origin. They combine with water to produce quaternary ammonium hydroxides, similar in constitution, alkalinity, and basicity to ammonium hydroxide ; and with acids, without elimination of hydrogen, to form salts, similar to the ammoniacal salts. The aliphatic monamines are the most simply constituted of a great variety of nitrogen derivatives, including the primary mon- amides, the diamides, such as urea, and the vegetable alkaloids, which have this in common with the amines, that they are basic in character, and in combining with acids, form salts in the same manner as ammonia does, i.e., by change of the nitrogen valence from three to five, and, consequently, without elimination of hydrogen ; thus : /H N H \H Ammonia. /H H 2 =N H \C 2 H 3 2 Ammonium acetate. /H N H \CH 3 Monomethyl- aniine. /CH 8 H 2 =N CH 8 \C1 Dimethylammo- niuin chloride. NH 2 NH 2 CH 2 CH a I I X\ /\ CO CO H 2 C CH 2 H 2 C CH 2 NH 2 N NO, H 2 C CH 2 H 2 C CH 2 \X \/ N N I /\\ H Cl H 2 Urea. Urea nitrate? Piperidine. Piperidine hydrochloride. The naming of these compounds has been the subject of much discussion. As the substances formed by the union of ammonia with acids are regarded as salts of ammonium, not of ammonia, so these compounds are not salts of urea, piperidine, morphine, etc., but salts of hypothetical bases, containing a quin- quivalent nitrogen atom, which in the free base is trivalent. The names: ureium nitrate, piperidium chloride, morphium sulphate, etc., are therefore the analogues of ammonium acetate and dimethylammonium chloride. For the chlorine, bromine, and iodine compounds the names: piperidine hydrochloride, morphine hydrobromide, quinine hydroiodide, etc., may be conveniently retained, they being regarded as the free bases, plus hydrogen, plus the halogen. 294 TEXT-BOOK OF CHEMISTRY The following formulas indicate the constitution of the amines and their hydroxides and salts: /C 2 H 6 N H \H /CH, N C 2 H 5 \H /CH, N CH, \CH, (CH,) 4 N.OH (CVH.J.N.Cl Bthylamine. (Primary). Methyl- ethylaraine. (Secondary). Trimetbyl- amine. (Tertiary). Tetramethyl ammonium hydroxide. Tetrethyl ammonium chloride. The primary monamines, the hydramines, and the diamines may also be considered as derived from the monohydric and dihydric alcohols by substitution of NH 2 for OH. CH, CH, CH 2 OH CH 2 OH CH 2 NH a I I I I I CH 2 OH CH 2 NH 2 CH 2 OH CH 2 NH 2 CH 2 NH 2 Alcohol. Monamlne. Glycol. Hydramine. Diamine. The primary monamines are formed: (1) by distilling the iso- cyanic esters with caustic potash: CO :N.C 2 H 5 +2KOH=NH 2 .C 2 H 5 +C0 3 K 2 (2) By heating the alkyl iodides, or the nitric esters with alco- holic ammonia: C 2 H,I+NH 3 =NH 2 .C 2 H 5 +HI, or C 2 H 5 .N0 3 +NH 3 =NH 2 .C 2 H 5 +HN0 3 ; (3) By the action of nascent H in alcoholic solution upon the nitriles : CH 3 .CN+2H 2 =NH 2 .C 2 H 5 (4) By the action of nascent H upon the nitroparaffins : CH 3 .N0 2 +3H 2 =NH 2 CH 3 +2H 2 (5) From the monamides of the fatty series monoamines, con- taining one atom of carbon less than the amide, are formed by the action of bromine and potassium hydroxide. The reaction occurs in two stages. First a bromide is produced: C 2 H 5 .CO.NH 2 +Br 2 +KOH=rC 2 H 5 .CO.NHBr+KBr+H 2 which is in turn converted into the amine with loss of the car- bonyl group : C 2 H 5 .CO.NHBr+3KOH=rC 2 H 5 .NH 2 +C0 3 K 2 +H 2 0-f-KBr The secondary monamines are formed, as intermediate products, by the action of the alkyl iodides upon the primary monamines in the presence of excess of ammonia. The alkyl-ammonium iodide is first produced : NH 2 .C 2 H 5 +C 2 H 5 I=NH ( C 2 H 5 ) 2 HI and this reacts with the ammonia : NH(C 2 H 6 ) 2 HI+NH 3 =NH(C 2 H 6 ) 2 +NH 4 I AMINES AND AMMONIUM DERIVATIVES 295 The final products of the reaction are the tetrammonium iodides: N(C 2 H 5 ) 4 L The tertiary monamines are obtained by the dry distillation of the quaternary ammonium hydroxides, iodides, or chlorides: N(C 2 H 5 )J=N(C 2 H 5 ) 3 +C 2 H 5 I or by heating the primary or secondary amines with excess of potassium alkyl sulphate: NH(CH3) 2 +CH 3 K.S0 4 =N(CH 3 ) 3 +KHS0 4 The primary and secondary amines react with esters of 'the mono- carboxylic acids to form alcohols and primary or secondary amides. Thus methylamine and methyl acetate produce ethyl alcohol and acetamide : H 2 N.CH 3 +CH 3 .COO ( CH 3 ) =CH 3 .CH 2 OH+H 2 N. ( CO.CH 3 ) The primary monamines, when warmed with chloroform and alco- holic potash, yield carbylamines, isocyanides, or isonitriles: NH 2 .C 2 H 5 +CHC1 3 +3KOH=CN.C 2 H 5 +3KC1+3H 2 (See Chloroform, test 1, p. 206.) When ethereal solutions of primary monamines and of carbon disulphide are evaporated, a residue is obtained which, when heated in aqueous solution with AgN0 3 , or FeCl 3 , or HgCl 2 forms a sul- phide of the metal and a "mustard oil," having a pungent odor. This is Hoffman's test for primary monamines. Methylamine H 2 N.CH 3 is a colorless, inflammable gas, having a fishy, ammoniacal odor. Very soluble in water (1,154 volumes in one at 12.5), forming a highly caustic and alkaline solution. It neutralizes acids with formation of methyl ammonium salts, which are soluble in water. Dimethylamine HN(CH 3 ) 2 is a liquid below 7.2, has an ammoniacal odor, and is very soluble in water. Its chloroplatinate forms yellow needles. Trimethylamine N(CH 3 ) 3 is formed by the action of methyl iodide upon NH 3 , and as a product of decomposition of many organic substances. It occurs naturally in combination in cod-liver oil, ergot, chenopodium, yeast, guano, and many flowers. It is an oily liquid below 9, having a fishy odor, alkaline, soluble in water, alcohol and ether. Tetr am ethyl-ammonium Hydroxide HO.N(CH 3 ) 4 is a quater- nary ammonium hydroxide, corresponding to ammonium hydroxide, and is obtained by decomposing the iodide, IN(CH 3 ) 4 , which is formed by the action of methyl iodide upon trimethylamine. It is a crystalline, deliquescent, caustic solid, not volatile without decomposi- tion. Like other carbon-nitrogen hydroxides and hydramines, it absorbs carbon dioxide from the air. 296 TEXT-BOOK OF CHEMISTRY OXYAMINES (HYDRAMINES), DIAMINES The primary monamines may be considered as being derived from the monoatomic alcohols by the substitution of the amido group, NH 2 , for the hydroxyl. From the dihydric alcohols, the glycols, two classes of amido compounds may be similarly derived. One of these, the oxyamines, hydroxamines, or hydramines, contain a single amido group, and retain an alcoholic hydroxyl. In the diamines both hydroxyls are replaced by amido groups. The oxyamines are primary, secondary and tertiary in the same manner as the monamines : CH 2 OH CH 2 OH CH 2 NH 2 CH 2 (OH).CH 2 \ CH 2 (OH).CH 2 \ NH CH 2 (OH).CH 2 N CH 2 OH CH 2 NH 2 CH 2 NH 2 CH 2 (OH).CH 2 / CH 2 (OH).CH 2 / Glycol. Oxyethyl- Dlinethylene Dioxyethyl Trioxyethyl amine. dlainine. ainine. aniine. Aldehyde-ammonia (p. 319), a crystalline solid formed by the ac- tion of dry NH 3 on acetic aldehyde: CH 3 .CHO+NH 3 =CH 3 .CH<^ may be considered as ethidene hydroxylamine in which both OH and NH 2 are attached to the same carbon atoms. Choline TrimethyloxetJiylammonium hydroxide Bilineurine CH 2 OH OH ^^ occurs in hops, in fungi, in certain seeds, in the CH 2 .N=(CH 8 ) 3 . human placenta, in bile, in the yolks of eggs, and in the cerebro-spmal fluid in epilepsy and other organic diseases of the nervous system. It is a constituent of the lecithins. It is formed synthetically (as its chloride) by the union of ethylene chlorhydrine and trimethylamine: CH 2 OH CH 2 OH Cl 4- N(CH 8 ) 8 = | / OH 2 C1 CH 2 -N=(CH 8 ), It is produced during the first forty-eight hours of putrefaction of animal tissues, from the decomposition of the lecithins, and diminishes from the third day, when other ptomaines (neuridine, putrescine, cadaverine) increase in amount. When heated, it splits up into glycol and trimethylamine. Nitric acid converts it into muscarine. It is a thick syrup, soluble in H 2 and in alcohol, and strongly alkaline in reaction. Even in dilute aqueous solution it prevents the coagulation of albumin and redissolves coagulated albumin and fibrin. It is a strong base; attracts C0 2 from the air; forms with HC1 a salt, soluble in alcohol, which crystallizes in plates and needles, resembling those of cholesterin. Its chloroplatinate is purified with difficulty; its chloroaurate readily. It is poisonous only in large doses. Amanitine Trimethyloxethylideneammonium hydroxide Isocho- C* TT OTT / is an isomere of choline, existing along with CHOH.N=(CH 8 ), OXYAMINES AND DIAMINES 297 muscarine in Agaricus muscarius. It is produced by methylation of aldehydeammonia : CH 3 .CHOH.NH 2 . By oxidation with HN0 3 it yields muscarine. CH 2 OH OH Muscarine. I / is related to choline, neurine and CHOH.N~(CH 3 ) 8 amanitine from which it may be obtained by oxidation. It occurs in nature in Agaricus muscarius, and is produced dur- ing putrefactive decomposition of proteins. The free base 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 hydroxide. When decom- posed it yields trimethylamine. Its chloroplatinate crystallizes in octahedra. Its chloride forms colorless, brilliant, deliquescent needles. When administered to animals, muscarine causes increased secre- tion of saliva and tears ; vomiting ; evacuation of f eces, 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 ; gradual sinking of the heart 's action and respiration; and death. Atropine prevents the action of muscarine and diminishes its intensity when already established. CH a OH Neurine Trimetliylvinylammonium hydroxide 1 1 / is CH.N = (CH 3 ) 8 a base resembling choline, for which reason it is considered here, al- though its proper place is as a derivative of vinylamine. It has been obtained from brain tissue and from the suprarenal capsule, prob- ably as a product of decomposition of protagon. It is produced from choline by boiling with baryta water. The same body is one of the alkaloids produced by the putrefaction of muscular tissue, and is endowed with poisonous qualities, resembling, but less intense than, those of muscarine. Betaines are lactams (p. 323) of hypothetical substances, such CH 2 OH as that which would be derived from choline : I /OH by oxida- 6l 2 .N=(CH 8 ) 8 COOH tion of the methoxyl group to a carboxyl: I /OH . Although CH 2 .N =( CH 3 ) 3 this substance, containing both carboxyl and basic hydroxyl, is un- known, the corresponding betaine aldehyde and chloride are known (see formulae below). COOH OH The betaines have the general formula: | / , in which R" R" N = may be any bivalent hydrocarbon radical, and in which the three 298 TEXT-BOOK OF CHEMISTRY remaining nitrogen valences may be satisfied by univalent radicals or by a trivalent radical. Or the arrangement of the valences may be reversed, as in nicotic-methyl beta'ine: I (C 5 H 4 )"' = N CH 8 . Betaine Trimefhyl-acetic betaine Oxyneurine Oxycholine COO TrimetJiyl-glycocoll I \ _ was first obtained from beet- juice (Beta vulgaris). It exists in beet-sugar molasses, in cotton- seed, and in malt. It is formed by several synthetic methods, e.g., by the action of methyl iodide upon amido-acetic acid (p. 323) : COOH COO -f 3CH 8 I=3HI+ I \ ; or by the interaction of mono- CH 2 .NH 8 CH 2 N ~ ( CH 3 ) 8 . chloracetic acid and trimethylamine : COOH COO I + N(CH 3 ) 3 = | \ +HC1 CH 2 C1 CH 2 N=(CH 3 ) 3 Betaine crystallizes in large, deliquescent crystals, with one mole- cule of water of crystallization, very soluble in water and in alcohol. It is decomposed by heat with evolution of trimethylamine, a fact which is utilized to obtain that substance from beet-molasses. It is strongly basic and forms crystalline salts. Its chloraurate is crys- talline and very sparingly soluble in cold water. The relations of the oxyamine bases are shown in the following formulae : CH, CH, CH 2 OH CH, CH, C HOH CH 2 OH CHOH (CH 3 ) 8 OH Ethyl-trlmethyl ammonium hydroxide. COH (CH 8 ) 8 OH Choline. COOH /STT V^JHj (CH 8 ) 8 OH Betaine aldehyde. (CH 8 ) 8 C1 Betaine hydrochlorlde. (CH 8 ) 3 OH Isochollne, (Amanltlne). COO, Oidj 1 ,// (CH 8 ) 8 Betaine /// (CH 8 ) 8 OH Muscarine. CH, CH Ji (CH 3 ) 8 OH Neurlne. Diamines are primary, secondary, and tertiary, as they contain two groups NH 2 , or two groups NH, or two N atoms : Trlmethylene dlamlne. \T /CH 2 .CH 2 \ T ^\CH 2 .CH 2 /^ Dlethylene dlamlne. /CH 2 .CH 2 \ N CH 2 .CH 2 N \CH 2 .CH 2 / Trletbylene dlamlne. OXYAMINES AND DIAMINES 299 The primary diamines only are acyclic compounds. They have the algebraic formula: N 2 CnH2n + *; the secondary, N2CnH2n+2; and the tertiary, N2CnH2n. The secondary and tertiary diamines are not known beyond the ethylene compounds and are cyclic compounds (see Piperazine). The primary diamines are obtained (1) by the reduction of the olefine dicyanides. Thus ethylene cyanide yields tetramethylene diamine : CN.CH 2 .CH 2 .CN+4H 2 =H 2 N.CH 2 .CH 2 .CH 2 .CH 2 .NH 2 (2) As hydrobromides, by heating the olefine bromides with alco- holic ammonia to 100 under pressure: BrCH 2 .CH 2 Br+2NH 3 =H 3 Br : :N.CH 2 .CH 2 .N : :H 3 Br (3) By reduction of the dinitroparaffins : N0 2 CH 2 .CH 2 N0 2 +6H 2 =H 2 N.CH 2 .CH 2 .NH 2 +4H 2 (4) By elimination of C0 2 from the diamido acids by bacterial action. Alkyls or acidyls may be substituted for H in NH 2 of the diamines, as in the monamines (p. 294). The formation of their dibenzoyl derivatives: (C 6 H 5 .CO).HN.(CH 2 ) 4 .NH.(CO.C 6 H 5 ) by the action upon them of benzoyl chloride in the presence of NaOH is utilized for their identification (see pp. 225, 284). Nitrous acid acts upon them as upon the monamines with the formation of glycols : H 2 N.CH 2 .CH 2 .NH 2 -j-2HN0 2 =CH 2 OH.CH 2 .CH 2 CH 2 OH+2N 2 +2H 2 Among the diamines are included several of the products of putre- faction known as ptomaines. Ethylenediamine H 2 N.(CH 2 ) 2 .NH 2 is a strongly alkaline liquid, boiling at 116.5. With acetyl chloride it forms diacetyl- CH 2 .NH.CO.CH 3 ethylene diamine, I , which is decomposed by heat with CH 2 .NH.CO.CH 3 formation of a cyclic amidine base, ethylene-ethenyl amidine, or CH 2 .NH . lysidine, | \ C.CH 3 . CH 2 .N // Trimethylenediamine H 2 N.(CH 2 ) 3 .NH 2 is said to have been obtained from the cultures of the comma bacillus. It has been ob- tained synthetically. It is an alkaline liquid, boiling at 135 . Tetramethylenediamine Putrescine H 2 N. ( CH 2 ) 4 .NH 2 is pro- duced along with cadaverine, during the putrefaction of muscular tissue, internal organs of man and animals, and of fish, and in the culture media of the comma bacillus from three days to four months. The free base is a colorless liquid (solid below 27) having a seminal odor, which absorbs C0 2 from the air and unites with acids to form crystalline salts. It is not actively poisonous. Pentamethylenediamine Cadaverine H 2 N. ( CH 2 ) 5 .NH 2 is iso- 300 TEXT-BOOK OF CHEMISTRY meric with neuridine and is produced during the later stages of putre- faction of many animal tissues, the choline disappearing as this and the other diamines are formed. The free base is a clear syrupy liquid, having a strong disagreeable odor, resembling that of coniine, boils at 175 , and fumes in air. It absorbs C0 2 rapidly, with formation of a crystalline carbonate. Its salts are crystalline. The chloride on dry distillation is decomposed into ammonium chloride and piperidine. Neuridine CgHj^N-j a diamine of undetermined constitution, isomeric with cadaverine, is produced, along with choline, during the earlier stages of putrefaction, particularly of gelatinoid sub- stances, and increases in quantity as putrefaction advances, while the quantity of choline diminishes. The free base is a gelatinous sub- stance, having a very marked seminal odor, readily soluble in water, insoluble in alcohol and in ether. Its chloride is crystalline and very soluble in water. It seems to be non-poisonous when pure. Saprine C 4 H 16 N 2 another diamine of undetermined constitu- tion has been obtained from putrid spleens and livers after three weeks' putrefaction. Mydaleine is still another putrid product of undetermined com- position, but probably a diamine containing four or five carbon atoms, which forms a difficultly crystallizable, hygroscopic chloride, which is actively poisonous. Five milligrams administered hypo- dermically to a cat causes death after profuse diarrhea and secretion of saliva, violent convulsions, and paralysis, beginning with the ex- tremities and extending to the muscles of respiration. AMIDINES AMIDOXIME& HYDROXAMIC ACIDS. The amidines contain both the amido group, NH 2 , and the imido group, NH, and have the general formula: RC^g z , in which R is any univalent hydrocarbon radical. They are formed by heating the nitriles (p. 305) with ammonium chloride. Thus acetonitrile yields acetamidine: CH 3 .C. : N+NH 4 C1=HC1+CH 3 .C/|' They are also formed by action of HC1 upon the amides. Indeed, they may be considered as being derived from the amides (p. 310) by substitution of NH for the carbonyl oxygen: +CH 3 .COOH (CH 3 .C/^ H '=acetamide; CH 3 .C /****' =acetamidine.) The amidines are monacid bases, very unstable when free. The amidoximes are derived from the amidines by substitution of OH for hydrogen, e.g., CH 3 .C/^ 2 pp ethenylamidoxime. They are GUANIDINE AND ITS DERIVATIVES 301 very unstable compounds, formed by the action of hydroxylamine upon nitriles or upon amidines. Hydroxamic acids contain the oxime group, N.OH, while the amido group of the amidine is replaced by hydroxyl: CH 3 .C^^ H acetohydroxamic acid. GUANIDINE AND ITS DERIVATIVES. Guanidine Carbotriamine CH 5 N 3 was first obtained by oxida- tion of guanine. It is formed (1) by heating ethyl orthocarbonate with ammonia : C(OC 2 H 5 ) 4 +3NH 3 =HN:C:(NH 2 ) 2 +4CH 3 .CH 2 OH (2) From cyanogen iodide and ammonia: CNI-f 2NH 3 =HN :C : (NH 2 ) 2 +HI (3) As hydrochloride from cyanamide and ammonium chloride: CN.NH 2 +NH 4 C1=C1H 2 . : N :C : (NH 2 ) 2 Substituted guanidines may be obtained by method (3) by using hydrochlorides of primary amines: Guanidine, containing the group -Cg 2 , is an amidine. It may also be considered as a triamine, derived from three ammonia mole- cules, H 2 N Cvf^H 2 - ^ * s re l a ted. to amidocarbonic acid, to urea and to pseudourea, as is indicated by the formulae : NH _ C /NH 2 _ C /NH 2 NH " C \NH 2 \OH -\OH Guanidine. Urea. Pseudourea. Amido carbonic acid. It is a crystalline solid, which absorbs C0 2 and H 2 from the air, and forms crystalline salts. Methyl-guanidine Methyluramine HN :C (NH 2 ) NH ( CH 3 ) - was first obtained by the oxidation of creatine and of creatinine (see below). It has also been obtained as a product of putrefaction of muscular tissue at a low temperature in closed vessels, when it prob- ably results from the decomposition of creatine. It is a colorless, crystalline, deliquescent, strongly alkaline substance, and is highly poisonous. The relation of guanidine and methyl-guanidine to each other and to creatine and creatinine is shown by the following formulae: HN _ C /NH 2 HN-C /NH * u \NH 2 u \N ( CH 3 ) .CH 2 .COOH Guanidine. Creatine. HN _ r /NH 2 /NH - CO U \NH(CH 8 ) HN=C | \N(CH 3 )CH 2 Methyl-guanidine. Creatinine. 302 TEXT-BOOK OF CHEMISTRY Creatine Methyl-guanidine acetic acid C 4 H 9 N 3 2 +Aq is, as is shown by the above graphic formula, a complex amido-acid. It is a normal constituent of the juices of muscular tissue, brain, blood, and amniotic fluid. It is formed synthetically by the union of methyl glycocoll and cyanamide : 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. It is soluble in boiling H 2 and in alcohol, insoluble in ether ; crystallizes in brilliant, oblique, rhombic prisms; neutral; tasteless; loses Aq at 100; fuses and decomposes at higher temperatures. When long heated with H 2 0, or treated with concentrated acids, it loses H 2 0, 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 hydroxide. 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 100. A white precipitate, which turns black when heated, is also formed when a solution of creatine is similarly treated with mercuric chloride and potash. Creatinine Methyl-guanidine acetic lactam C 4 H 7 N 3 113 a product of the dehydration of creatine, is a normal and constant con- stituent of the urine and amniotic fluid, and also exists in the blood and muscular tissue. It crystallizes in oblique, rhombic prisms, soluble in H 2 and in hot alcohol, insoluble in ether. It is a strong base, has an alkaline taste and reaction ; expels NH 3 from the ammoniacal salts, and forms well-defined salts, among which is the double chloride of zinc and creatinine (C 4 H 7 N 3 0) 2 ZnCl 2 , obtained in very sparingly soluble, oblique prismatic crystals, when alcoholic solutions of creatinine and zinc chloride are mixed. HYDRAZINES HYDRAZIDES. The hydrazines are derivatives of hydrazine or diamidogen, H 2 N.NH 2 (p. 96), by substitution of aliphatic or aromatic radicals, alcoholic, phenolic or acid, for one or more of the hydrogen atoms in the same way as the amines are derived from ammonia. There are, therefore, primary, secondary, tertiary and quaternary hydrazines; and they may be symmetrical, as C 2 H 5 HN.NH.C 2 H 5 and C 6 H 5 .HN.- NH.C 2 H 5 , or unsymmetrical, as C H 5 HN.NH 2 and (C 2 H 5 ) 2 N.NH 2 . The aliphatic hydrazines are obtained from the alkyl-ureas, by con- version into nitroso-amines, and reduction. Most of the hydrazines, some of which are of considerable interest, are derivatives of phenyl- hydrazine, C H 5 HN.NH 2 , and, containing a cyclic chain C 6 H 5 . These CYANOGEN COMPOUNDS 303 will be considered among the aromatic compounds. The hydrazides, corresponding to the amides, contain acidyls. NITRILES CYANOGEN COMPOUNDS. These substances may be considered either as compounds of the univalent radical cyanogen (CN)', or as paraffins, CnH2n+2, in which three atoms of hydrogen have been replaced by the trivalent N"' atom, hence nitriles, compounds of N with the trivalent radicals CnEten-i. Hydrogen Cyanide Hydrocyanic acid Prussic acid Formo- nitrile Cyanogen hydride HC. : N exists ready formed in the juice of cassava, and is formed by the action of H 2 upon bitter almonds, cherry-laurel leaves, and other vegetable products containing amyg- dalin, a glucoside, which is decomposed into glucose, benzoic aldehyde (p. 362), and hydrocyanic acid, when warmed with water. It is also formed in a great number of reactions: by the passage of the electric discharge through a mixture of acetylene and nitrogen: HC;CH+N 2 =2HC:N By the action of chloroform on ammonia: NH 3 +CHC1 3 =3HC1+HCN By the distillation of, or the action of HN0 3 upon, many organic substances; by the decomposition of cyanides (see Nitriles, below). It is always prepared by the decomposition of a cyanide or a ferrocyanide, usually by acting upon potassium ferrocyanide with dilute sulphuric acid, and distilling. Its preparation in the pure form is an operation attended with the most serious danger, and should only be attempted by those well trained in chemical manipu- lation. For medical uses a very dilute acid is required; the acidum hydrocyanicum dilutum (U. S. P.) 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 ; crystallizes at 15 ; boils at 26.5; 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 react without excess with 1.27 gram of silver nitrate. The dilute acid deteriorates on exposure to light, although more slowly than the concentrated; a trace of phosphoric acid added to the solution retards the decom- position. Most strong acids decompose HCN. The alkalies enter into double decomposition with it to form cyanides. It is decomposed by Cl and Br, with formation of cyanogen chloride or bromide. Nascent H converts it into methylamine. 304 TEXT-BOOK OF CHEMISTRY Analytical Characters. (1) With silver nitrate: a dense, white ppt. ; which is not dissolved on addition of HN0 3 to the liquid, but dissolves when separated and heated with concentrated HN0 3 ; soluble in solutions of alkaline cyanides or thiosulphates. (2) Treated with NH 4 HS, evaporated to dryness, and ferric chloride added to the resi- due: a blood-red color, which is discharged by mercuric chloride. (3) With potash and then a mixture of ferrous and ferric sulphates: a greenish ppt., which is partly dissolved by HC1, leaving a pure dark-blue precipitate. (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 CuS0 4 , and, after drying, into the liquid to be tested. In the presence of HCN it assumes a deep-blue color. (6) Add a few drops of potassium nitrite solution, then two or three drops of ferric chloride solution, and enough dilute H 2 S0 4 to turn the color to yellow. Heat just to boiling; cool, add a few drops of NH 4 OH, filter, and add to the filtrate a few drops of dilute, colorless ammonium sulphydrate: a violet color, changing to blue, then to green and yellow. Toxicology. Hydrocyanic acid is a violent poison, whether it is inhaled 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 was time for con- siderable voluntary motion between the time of ingestion of the poison and unconsciousness. In the great majority of cases the patient is either dead or fully under the influence 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 remains. 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 ab- sorbed. The treatment indicated is directed to the maintenance of respira- tion; cold douche, galvanism, artificial respiration, until elimination has re- moved the poison. If the patient survives an hour after taking the poison, the prognosis becomes very favorable; in the first stages it is exceedingly un- favorable, unless the quantity taken has been very small. In cases of suspected homicide by hydrocyanic acid, the stomach should never be opened until immediately before the analysis. Cyanogen Chlorides. Two polymeric chlorides are known: Cyanogen chloride, CNC1, formed by the action of Cl upon anhydrous HCN or upon Hg(CN) 2 in the dark. It is a colorless gas, condensing to a liquid at 15 ; intensely irritating and poisonous. Tricyanogen chloride, C 3 N 3 C1 3 , is formed, as a crystalline solid, when anhydrous HCN is acted upon by Cl in sunlight. It fuses at 146. (See Cyanidine, p. 414.) CYANOGEN COMPOUNDS 305 Cyanides. The most important of the simple metallic cyanides are those of K and Ag. Nitriles. The hydrocyanic esters of the univalent alcoholic radi- cals are called acid nitriles, because of their formation from the amides, by the reaction given under (3) below. Hydrocyanic acid, being produced from f ormamide, is formonitrile ; methyl cyanide, de- rived from acetamide, is acetonitrile, etc. They are also derivable from the ammonium salt of the acid by elimination of the elements of two molecules of water. Their formulae may be derived from those of the acids by substitution of N for the trivalent OOH of the car- boxyl. The acid nitriles are not to be confounded with the acidyl cyanides, which are the nitriles of the ketonic acids. The nitriles are produced: (1) By heating the haloid esters (p. 205) with alcoholic solution of potassium cyanide at 100: CH 3 .CH 2 I+KCN=CH 3 .CH 2 .CN+KI (2) By distilling a mixture of potassium cyanide and the potas- sium salt of a monoalkyl sulphate. Thus, ethyl cyanide is produced from potassium ethylsulphate : KCN+S0 4 .C 2 H 5 .K=K 2 S0 4 +C 2 H 5 .CN (3) By complete dehydration, by the action of P 2 5 , of the ammoniacal salt of the acid, or of its amide. Thus acetonitrile is obtained from ammonium acetate: CH 3 COO (NH 4 ) =CH 3 .CN+2H 2 or from acetamide : CH 3 .CO.NH 2 =CH 3 .CN+H 2 (4) By the action of acidyl chlorides upon silver cyanate. Thus, with acetyl chloride, methyl cyanide is formed: CNOAg+CH 3 .CO.Cl=rAgCl+C0 2 +CH 3 .CN The formation of the nitriles is frequently utilized to pass from a given carbon compound to its next superior homologue. Thus ethyl alcohol may be obtained from methyl alcohol by the steps: H.CH 2 OH > CH 3 .I > CH 3 .CN -^> CH 3 .COOH > CH 3 .CHO >CH 3 .CH 2 OH (Seep. 251). The nitriles combine with nascent hydrogen to form primary amines. Thus acetonitrile forms ethylamine: CH 3 .CN+2H 2 =C 2 H 5 .NH 2 Hydrating agents convert them into the ammonium salts of the cor- responding acids. Thus ammonium propionate is derived from ethyl cyanide: C 2 H,.CN+2H,0=C 2 H 5 .COO(NH 4 ). Or, when acted upon by concentrated sulphuric acid, hydrogen peroxide, or concentrated hydrochloric acid, they take up one molecule of water and form 306 TEXT-BOOK OF CHEMISTRY amides. Thus acetonitrile forms acetamide: CH 3 .CN-f-H 2 0= CH 3 .CO.NH 2 . Methyl Cyanide Acetonitrile CH 3 .CN is a colorless liquid, b. p. 81.6, having an agreeable odor, sparingly soluble in water, obtained by distilling ammonium acetate or acetamide with P 2 5 . The isocyanides, carbylamines, or carbamines, are isomeres of the nitriles, which differ from the latter in constitution in that, in the nitriles, the nitrogen is trivalent, and the alkyl group is in union with carbon, e.g., methyl cyanide, N=C CH 3 , while in the carbylamines the nitrogen is quinquivalent, and the alkyl is in union with nitrogen, e.g., methyl isocyanide, C = N CH 3 . The difference in constitution between the nitriles (alkyl cyanides) and the alkyl isocyanides is shown by the difference in their behavior with hydrating agents. While the cyanides yield the ammonium salts of the corresponding acids : CH 3 .CH 2 .CN+2H 2 0=CH 3 .CH 2 .COO(NH 4 ) the isocyanides are split into a primary amine and formic acid: CH 3 .CH 2 .NC+2H 2 0=CH 3 .CH 2 .NH 2 +H.COOH The alkyl magnesium halides act differently upon cyanides and isocyanides. With the former an addition product is formed accord- ing to the equation : R.Mg.X+R'.CN=RR' :C :N.MgX, which when hydrolyzed produces ketones: RR' :C :N.MgX+2H 2 0=R.CO.R'+NH 3 +HOMgX With the isocyanides the addition is : R'.N=C+RMgX=R'N :C <^ gX which when hydrolyzed produces imines : R'N :C <^ gX +H 2 0=R'N :CH.R+HO.MgX The isocyanides are formed: (1) by the action of a primary mon- amine on chloroform in the presence of caustic potash. Thus methyl isocyanide is derived from methylamine: CH 3 .NH 2 +CHC1 3 =3HC1+CN.CH 3 (2) By the action of alkyl iodides upon silver cyanide: CH 3 I+AgCN=AgI+CN.CH 3 Methyl Isocyanide Methylcarbylamine Isoacetonitrile CH 3 .- NC is a colorless liquid, b. p., 58, having a disagreeable odor, and giving off highly poisonous vapor. It is formed by the reactions given above, and is said to exist in the venom of toads. Phenyl Isocyanide Isobenzonitrile C 6 H 5 .NC is a colorless liquid, not boiling without decomposition, having an intensely dis- agreeable odor, whose formation is utilized in a test for chloroform. Both nitriles and isonitriles combine with the hydracids to form CYANOGEN COMPOUNDS 307 crystallite salts, decomposable by water; the latter much more en- ergetically than the former. They are all volatile liquids ; the nitriles having ethereal odors when pure, the isonitriles odors which are very powerful and disagreeable. Dicyanogen CN.CN is prepared by heating mercuric cyanide, and is also formed by passing an electric arc between carbon points in an atmosphere of nitrogen. It is a colorless gas, has a pronounced odor of bitter almonds: sp. gr., 1.8064 A. It burns in air with a purple flame, giving off N and C0 2 . It is quite soluble in water, but the solutions soon turn brown, and then contain ammonium oxalate and formate, urea, and hydrocyanic acid. Nitriles of Carbonic and Thiocarbonic Acids. These constitute the oxygen and sulphur compounds of cyanogen. Thus cyanic acid is the nitrile of carbonic acid: C0 3 H(NH 4 )=CONH+2H 2 0, and thiocyanic acid that of thiocarbonic acid: C0 2 SH(NH 4 )=CSNH+ 2H 2 0. Three structural formula of these compounds are possible: N=C.- OH, 0=C=N.H, and CEEN.OH. The first structure is that of the normal cyanic and thiocyanic acids, the second that of the isocyanates and isothiocyanates, the third that of fulminic acid. Cyanic Acid NC.OH is obtained by distillation of cyanuric acid, or, in its salts, by calcining the cyanides in presence of an oxi- dizing agent, or by the action of dicyanogen upon solutions of the alkalies or alkaline carbonates. It is a colorless liquid, only stable below 0; has a strong odor, resembling that of formic acid ; and is soluble in water ; gives off an irritating vapor ; is vesicating to the skin ; and is changed by exposure to air into its polymere, cyamelide, a white, porcelain-like solid. Cyanuric Acid Tricyanic acid Trioxycyamdine HO.- C \2fcC(OH)/N is produced by dry distillation of uric acid; by the action of heat or of Cl upon urea ; by heating tricyanogen chloride or bromide with water or with alkalies. It forms colorless crystals, odorless, almost tasteless, feebly acid, rather soluble in water. It is tribasic. It may be dissolved in strong H 2 S0 4 ox HN0 3 without de- composition, but, when boiled with acids or alkalies, it is decomposed into carbon dioxide and ammonia; and, when distilled, into cyanic acid. The ordinary potassium and ammonium cyanates are regarded as isocyanates, salts of isocyanic acid, or carbimide, : C : NH. The ammonium salt, 0:C:N(NH 4 ), is converted into its isomere, urea, H 2 N.CO.NH 2 , by evaporation of its solution. The isocyanic esters serve for the generation of the alkyl ureas. Fulminic Acid Carbyloxime CEEN.OH is a strongly acid sub- stance, having the odor and poisonous qualities of hydrocyanic acid, 308 TEXT-BOOK OF CHEMISTRY whose Ag and Hg salts are formed by the action of nitrous acid upon alcohol and silver, or mercuric, nitrate. Mercuric fulminate, or fulminating mercury, crystallizes in white, soluble needles, and ex- plodes violently upon shock. It is used in percussion caps, primers and cartridges. Silver fulminate is more violently explosive than the mercurial salt. Fulminating gold is not a fulminate, but auro- amidoimide, Au(NH)NH 2 +3H 2 0. Fulminuric Acid CN.CH(N0 2 ).C \^K metameric with cyan- uric, and polymeric with cyanic and isocyanic acids, is a deriva- tive of tartronic acid, COOH.CHOH.COOH ; whose alkali salts are formed by boiling solutions of alkaline chlorides with mercuric fulminate. Thiocyanic Acid Sulphocyanic acid Cyanogen sulphydrate N=C.SH is obtained by decomposition of its salts, which are formed by boiling solutions of the cyanides with sulphur; by the action of dicyanogen upon the metallic sulphides ; and in several other ways. The free acid is a colorless liquid, crystallizes at 12.5, acid in reaction. The prominent reaction of the acid and of its salts is the formation of a deep-red color with the ferric salts; the color being discharged by mercuric chloride - solution. Thiocyanates exist in the human saliva and in the stomach-con- tents, in small amount. The free acid is poisonous. Isothiocyanic Esters Mustard oils Isothiocyanic acid, S :C :- NH, is not known in the free state. Its esters are called mustard oils, from the most important of the class, allyl isothiocyanate, which is the essential oil of mustard. The mustard oils are obtained: (1) by mixing ether solutions of primary amines and carbon disulphide, and evaporating the solu- tions, the amine salts of alkyl dithiocarbamic acids are formed: CS 2 +2C 2 H 6 .NH 2 =SC On boiling aqueous solutions of these with AgN0 3 , FeCl 3 or HgCl 2 , the metallic sulphides are precipitated, and hydrogen, sulphide and the mustard oils are formed, the latter distilling over. The reaction takes place in two stages: sr /NH.C a H 5 A N0 9r /NH.C a H 6 , N0 N ^ H and U \ S ( NH 3 .C 2 H 6 ) AgN 3 C \ SAg \ C 2 H B 8 Ethylammonium Silver Silver Etliylnnnnoniuni ethylthiocarbamate. nitrate. ethyldithiocarbamate. nitrate. + H ' S + 2SC:N.C 1 H. Ethyl iaocyunate. Hoffman's test for the primary amines (p. 295) is based upon these reactions. The mustard oils are liquids, insoluble in water, giving off vapors of penetrating odor and irritating to the eyes. When heated with CYANOGEN COMPOUNDS 309 water under pressure to 200, or with hydrochloric acid to 100, they are decomposed into carbon dioxide, hydrogen sulphide and amines : SC :N.C 2 H 5 +2H 2 0=C0 2 +SH 2 +NH 2 .C 2 H 5 Heating with dilute H 2 S0 4 decomposes them into amines and carbon oxysulphide, COS. With nascent hydrogen they yield thio- f ormaldehyde and a primary amine : SC :N.C 2 H 5 +2H 2 =H.CSH+NH 2 .C 2 H 5 Heated with monocarboxylic acids they form carbon oxysulphide, esters, and monamides: SC:N.C 2 H 5 +2CH 3 .COOH=COS+CH 3 .COO.C 2 H 5 +NH 2 .CH 3 .CO Their alcoholic solutions, when boiled with HgO, yield isocyanic esters, which are converted by water into the corresponding com- pound ureas. Cyanamide CN.NH 2 is the nitrile of carbamic acid : OC :NH 2 .- O.NH 4 . 2H 2 0=CN.NH 2 . It is formed by the action of cyanogen chloride upon ammonia: CNC1+2NH 3 =NH 4 C1+CN.NH 2 or by the action of thionyl chloride upon urea : NH 2 .CO.NH 2 +SOC1 2 =CN.NH 2 +S0 2 +2HC1 It forms colorless crystals, soluble in water, alcohol or ether. Corresponding to it are substituted cyanamides, which may be formed by using a primary amine in place of ammonia in the above-men- tioned method of preparation: CNC1+2NH 2 .CH 3 =NH 3 .CH 3 .C1+CN.NHCH 3 Heated with ammonium chloride it forms guanidine hydrochloride : CN.NH 2 +NH 4 C1=H 3 C1N.C ^ Hydrating agents convert it into urea: CN.NH 2 +H 2 0=rH 2 N.CO.NH 2 . Metallocyanides. The metallic compounds of cyanogen, the cya- nides, may be divided into three classes: (1) the simple cyanides, such as potassium, silver, or mercuric cyanide, which resemble in consti- tution and general characters the chlorides, bromides, and iodides; (2) the double cyanides, such as AgK(CN) 2 , or HgK 2 (CN) 4 , which are constituted like other double salts. These salts have crystalline forms and solubilities of their own, independent of those of the sim- ple cyanide of which they are made up. They are readily decomposed by cold acids, with liberation of hydrocyanic acid; (3) compound cyanides, or metallocyanides, in which the cyanogen groups are more intimately attached to the metal, in such manner that the ordinary analytical characters of the metals are completely masked ; and when 310 TEXT-BOOK OF CHEMISTRY they are decomposed by cold acids hydrocyanic acid is not liberated, but a complex metallohydrocyanic acid, corresponding in constitution to the salt. The metals entering into the composition of the metal- locyanides are iron (ferro- and ferricyanides), cobalt (cobalticya- nides), and platinum (platinocyanides) ; also chromium and manga- nese in the ic form. The metallocyanides are considered as derivatives of two hypo- thetical acids, polymeres of hydrocyanic acid: dihydrocyanic acid and trihydrocyanic acid, which, in the hydrometallocyanic acids and their salts, are combined with the constituent metal, with loss of hydrogen, as shown in the following formulae: H C=N H C=N C H N=C H N=CH N Dihydrocyanic acid. Trihydrocyanic acid. _ //C 3 N 3 .K ~ /C,N 8 .K, * e \C 3 N 3 .K 2 pt /C 2 N 2 .H Fe \C 8 N s .K a J e //C 3 N 8 .K Pt \C 2 N 2 .H e \C 8 N 8 .K a Potassium Potassium Hydroplatlnocyanlc ferrocyanlde. ferrlcyanlde acid. Hydronitroprussic Acid Fe(CN) 5 (NO)H 2 contains the nitroso group NO, and is produced when potassium ferrocyanide is acted upon by nitric acid. Its sodium salt, sodium nitroprusside, is formed by neutralizing the acid with sodium carbonate. It forms brilliant red prisms; and is used as a test for sulphides, with which it forms a violet color. (See test No. 6, Hydrocyanic acid, p. 304.) AMIDES. These compounds are similar in constitution to the amines (p. 292), from which they differ in that the radicals substituted in ammonia are acidyls in place of alkyls: N^j- CH ' ; N^ caCH ' )2 ; N(CO.CH 3 ) 3 . Like the amines they are classified into monamides, diamides and triamides, according as they are derived from one, two, or three molecules of ammonia. Mixed amides are also known, produced by the substitution of acid radicals for the remaining hydrogen of the primary and secondary amines, e.g., diethyl acetamide: CH 3 CO(C 2 H 5 ) 2 N. MONAMIDES AMIC ACIDS. Like the monamines, the monamides are primary, secondary, or tertiary, as they contain one, two or three substituted radicals. The primary monamides corresponding to the monocarboxylic acids may also be considered as being derived from those acids by AMIDES 311 substitution of NH 2 for the OH of the group COOH ; as the amines are derivable from the alcohols by substitution of NH 2 for OH in CH 2 OH, CHOH or COH. Thus acetamide, CH 3 .CO.NH 2 is derived from acetic acid, CH 3 .CO.OH. The primary monamides are formed: (1) by the action of heat upon the ammonium salt of the acid, with elimination of the ele- ments of one molecule of water : CH 3 .COO (NH 4 ) =H 2 0+CH 3 .CO.NH 2 It will be remembered that the nitriles (p. 305) are derived from the ammoniacal salts by elimination of two molecules of water : CH 3 .COO (NH 4 ) =2H 2 0+CH 3 .CN (2) By addition of H 2 to the nitriles. Thus hydrogen peroxide in alkaline solution converts acetonitrile into acetamide: 2CH 3 .CN+2H 2 2 =2CH 3 .CO.NH 2 +0 2 (3) By the action of ammonia upon esters. Thus, ethyl acetate and ammonia produce acetamide and ethylic alcohol : CH 3 .COO(C 2 H 5 )+NH 3 =CH 3 .CO.NH 2 +CH 3 .CH 2 OH (4) By the action of an acidyl chloride upon dry ammonia. Thus, acetamide is produced by acetyl chloride : CH 3 .CO.C1+2NH 3 =NH 4 C1+CH 3 .CO.NH 2 The secondary monamides are obtained: (1) by the action of acidyl chlorides upon the primary monamides. Thus, diacetamide is produced from monacetamide : CH 3 .CO.NH 2 +CH 3 .CO.C1=HC1+(CH 3 CO) 2 NH (2) By the action of hydrochloric acid upon the primary mon- amides at high temperatures: 2(CH 3 .CO.NH 2 )+HC1=NH 4 C1+(CH 3 CO) 2 NH The tertiary amides 01 this series have been imperfectly studied. Some have been obtained by the action of acidyl chlorides upon me- tallic derivatives of secondary amides: (CH 3 .CO) 2 NaN+CH 3 .CO.Cl=(CH 3 .CO) 3 N+NaCl or by the union of anhydrides and nitriles at 200 : CH 3 .CN+(CH 3 .CO) 2 0=(CH 3 .CO) 3 N The primary monamides of the fatty acids are solid, crystalliz- able, neutral in reaction, volatile without decomposition, mostly solu- ble in alcohol and ether, and mostly capable of uniting with acids to form compounds similar in constitution to the ammoniacal salts: H 2 N.CO.CH 3 +HN0 3 =(H 3 N.CO.CH 3 )N0 3 312 TEXT-BOOK OF CHEMISTRY They arc capable of uniting with H 2 to form the ammoniacal salts of the corresponding acids : H 2 N.CO.CH 3 +H 2 0=CH 3 .COO (NH 4 ) And with the alkaline hydroxides to form the metallic salts of the corresponding acids and ammonia: H a N.CO.CH 3 +KOH=CH 3 .COOK+NH 3 They are converted into amines containing one atom of carbon less than themselves by the action of bromine and alkali. The sec- ondary monamides, containing two radicals of the tatty series, are acid in reaction, and their remaining atom of extra-radical hydrogen may be replaced by an electro-positive atom. The action of bromine on the amides in alkaline solution, results in the formation of amines containing one atom of carbon less. The reaction takes place in two stages, with intermediate formation of a bromamide: (CH 3 .CO).NH 2 +Br 2 +KOH=(CH 3 .CO)NHBr+KBr+H 2 0, and (CH 3 .CO)NHBr+3KOHr=CH 3 .NH 2 +C0 3 K 2 +KBr+H 2 As the amides are readily obtained by dehydration of the NH 4 salts of the acids, and as the amines yield alcohols which may in turn be oxidized to acids: CH 3 .NH 2 +HN0 2 =H.CH 2 OH+N 2 +H 2 this offers a means of "stepping down." Formamide CHO.NH 2 45 is a colorless liquid, soluble in H 2 and in alcohol, boils at 192-195, suffering partial decomposi- tion, obtained by heating ethyl formate with an alcoholic solution of ammonia, or by the dry distillation of ammonium formate. It is de- composed by dehydrating agents, with formation of hydrocyanic acid: H 2 N(H.CO)=rHCN+H 2 0. Mercury formamide is obtained in solution by gently heating freshly-precipitated mercuric oxide with H 2 and formamide. Under the name chloralamide a compound, formed by the union of chloral and formamide, and having the constitution, CCl 3 .CH(^g CHO has been used as a hypnotic. It forms colorless, odorless, faintly bitter crystals, fusible at 115, sparingly soluble in water. It is decomposed by alkalies, chloroform and ammonia being among the products of the decomposition. It is not affected by acids. Chloralimide CCl 3 .C^g H is another related derivative, formed by the action of ammonium acetate upon chloral hydrate, or by heat- ing chloral ammonia. It is a crystalline solid, sparingly soluble in water, readily soluble in ether and in alcohol. When heated to 180 it is decomposed into chloroform and formamide. Acetamide CH 3 .CO.NH 2 is obtained by heating, under pres- AMIDES OF DICARBOXYLIC ACIDS 313 sure, a mixture of ethyl acetate and ammonium hydroxide, and puri- fying by distillation. It is solid, crystalline, very soluble in H 2 0, alcohol, and ether ; fuses at 82 ; boils at 222 ; has a sweetish, cooling taste, and an odor of mice. Boiling potassium hydroxide solution decomposes it into potassium acetate and ammonia. Phosphoric an- hydride deprives it of H 2 0, and forms with it acetonitrile or methyl cyanide: H 2 N.CO.CH 3 =:CH 3 .CN+H 2 0. AMIDES OF DICARBOXYLIC ACIDS. As the hydramines, the diamines (p. 296) and the imines are all derivable from the dihydric alcohols, by substitution of NH 2 .for OH in the first, of 2NH 2 for 20H in the second, and of NH for 20H in the last, so amic acids, diamides, and imides are correspond- ingly derived from the dicarboxylic acids: COOH CONH 2 CONH 2 C0\ I I I I NH COOH COOH CONH 2 CO/ Oxalic acid. Oxamic acid. Oxamide. Oximide. and, recognizing that carbonic acid is a pure dicarboxylic acid, al- though not a member of the oxalic series, we have : nn /OH /NH 2 /NH 2 - C \OH Carbonic acid. Carbamic acid. Carbamide. Carbimide. Amic acids are, therefore, acids derived from two carboxylic acid groups by substituting NH 2 for one OH. Carbamic Acid Amidoformic Acid H 2 N.CO.OH is not known in the free state, being decomposed into C0 2 and NH 3 , but ammonium carbamate is formed whenever ammonia and carbon dioxide are in contact: C0 2 +2NH 3 =rH 2 N.CO.O(NH 4 ), and it therefore exists in commercial ammonium carbonate, and is formed by oxidation of many carbon-nitrogen compounds, notably amido-acids, in alkaline solu- tion. It exists normally in the blood and urine, and is formed in the system as an intermediate product between amido-acids and urea. It is obtained by directing dry ammonia and carbon dioxide into cold absolute alcohol, as a white crystalline precipitate. The esters of carbamic acid, called urethanes, are more stable than its salts. They are formed by the action of ammonia upon the car- bonic esters: OC : (OC 2 H 5 ) 2 +NH 3 =H 2 N.CO.O ( C 2 H 5 ) +CH 3 .CH 2 OH and by the action of cyanogen chloride upon alcohols : CNC1+2CH 3 .CH 2 OH=H 2 N.CO.O(C 2 H 5 )+CH 3 .CH 2 C1 Ethyl urethane, produced by the above reactions, forms thin, large, transparent plates, f. p. 50, b. p. 184, very soluble in water 314 TEXT-BOOK OF CHEMISTRY and in alcohol. It is used as a hypnotic, either alone or combined with chloral in uralium, or somnal. Phenyl urethane, H 2 N.CO.O(C 6 H 5 ), is a light, white powder, almost insoluble in water, very soluble in alcohol, which is used as an antipyretic under the name euphorine. The primary diamides only are acyclic compounds (see diamines, p. 298). They are formed: (1) by the action of ammonia upon the neutral esters. Thus ethyl oxalate yields oxamide: CO.OC 2 H 6 CO.NH, + 2NH, = + 2CH 3 .CH 2 OH. CO.OC 2 H 6 CO.NH 2 (2) By heating the neutral ammonium salt of the corresponding acid. Thus ammonium carbonate yields carbamide: OC /ONH 4 oc /NH ' 2HO OC \ONH 4 OC \NH 2 2H ' Carbamide Urea H 2 N.CO.NH 2 exists in the urine of mam- malia, and, in smaller quantity, in the excrement of birds, fishes and some reptiles; also in the mammalian blood, chyle, lymph, liver, spleen, lungs, brain, vitreous and aqueous humors, saliva, perspira- tion, bile, milk, amniotic and allanto'ic fluids, and in serous fluids. Urea is formed by the methods given above; also, (1) as a product of decomposition of uric acid, usually by oxidation. Thus nitric acid oxidizes uric acid to urea and alloxan: 2C 6 H 4 N 4 3 +2H 2 0+0 2 =2CON 2 H 4 +2C 4 H 2 N 2 4 (2) By the hydrolysis of creatine. Thus urea and sarcosine are formed by the action of KOH upon creatine : C 4 H 9 N 3 2 +H 2 0=CON 2 H 4 +C 3 H 7 N0 2 (3) By the action of carbonyl chloride upon dry ammonia: COC1 2 +2NH 3 =CON 2 H 4 +2HC1 (4) By the action of barium hydroxide upon guanidine (p. 301), or upon the hexon bases, lysine and arginine, products of decomposi- tion of the proteins. (5) By atomic transposition of its isomere, ammonium isocyanate, by heat: :C :N.NH^H 2 N.CO.NH 2 (6) By the action of ammonia upon phosgene or upon urea chlorides : COC1 2 +4NH 3 =H 2 N.CO.NH 2 +2NH 4 C1, or H 2 N.CO.C1+2NH 3 =H 2 N.CO.NH 2 +NH 4 C1 (7) By heating ammonium carbamate to 130: H 2 N.CO.ONH 4 =H 2 N.CO.NH 2 +H 2 AMIDES OP DICARBOXYLIC ACIDS 315 (8) "By the action of ammonia upon urethane: H 2 N.CO.O(C 2 H 5 )+NH 3 =H 2 N.CO.NH 2 +CH 3 .CH 2 OH Urea crystallizes in long rhombic needles or prisms. It is color- less and odorless, and has a cooling taste, somewhat resembling that of saltpeter. It is neutral in reaction, although basic in character; soluble in one part of water, in five parts of cold alcohol, and in one part of boiling alcohol, sparingly soluble in amylic alcohol and in acetic ether, and still less soluble in ether. It fuses at 132. When heated a few degrees above its fusing point urea appears to boil, giving off ammonia and ammonium carbonate, and finally leaves a dry, solid residue, consisting of ammelide, C 3 H 4 N 4 2 , cyanuric acid, C 3 3 N 3 H 3 , and biuret, C 2 2 N 3 H 5 . This residue, dis- solved in water, gives a fine red-violet color with KOH and CuS0 4 (Biuret reaction). When added to a concentrated solution of fur- furole and hydrochloric acid, solid urea or urea nitrate forms a yellow solution, changing in color to green, blue and intense purple- violet. After a time the mixture thickens and blackens (Schiff's reaction). Dilute aqueous solutions of urea are not decomposed by boiling; but if the solution is concentrated, or the boiling prolonged, or the temperature raised above 100, the urea is partly decomposed into C0 2 and NH 3 . The same decomposition takes place more rapidly and completely under pressure at 140. It is also caused by bacterial action and by a urinary enzyme. Urea is decomposed into carbon dioxide, water and nitrogen by the alkaline hypochlorites and hypobromites, by chlorine and by nitrous acid. Strong acids and alkalies decompose it into carbon dioxide and ammonia. Urea forms definite compounds, not only with acids, but also with certain salts and oxides. Urea nitrate H 2 N.CO.NH 3 .N0 3 forms, in white crystals, when a concentrated solution of urea is treated with nitric acid in the cold. It is much less soluble than urea, especially in presence of an excess of nitric acid. It is decom- posed by evaporation of its solutions. Urea oxalate CO:(NH 3 ) 2 :- 4 C 2 separates as a fine, crystalline powder, from mixed concen- trated aqueous solutions of urea and oxalic acid. Its solutions may be evaporated without decomposition. When solutions containing molecular weights of urea and so- dium chloride are evaporated, prismatic crystals, containing CON 2 H 4 , NaCl+H 2 are obtained. Urea forms several compounds with mercuric oxide. Of these, the compound (CON 2 H 4 ) 2 , 4HgO, con- taining 72 parts of HgO for 10 parts of urea, is formed as a white, amorphous precipitate when a dilute solution of mercuric nitrate is gradually added to a dilute, alkaline solution of urea, and the excess of acid neutralized from time to time. 316 TEXT-BOOK OF CHEMISTRY THIOUREA AND THIOCARBAMIC ACIDS. The thio-compounds, corresponding to carbamic acid and to urea, in which oxygen is replaced by sulphur, exist either in their own forms or in their derivatives. Thus : /SH ~ r o.n ' \NH 2 S ' C \NH 2 S:C \NH 2 S: \NH 2 Thiocarbamic acid. Sulphocarbamic acid. Dithiocarbamic acid. Thiourea. Thiocarbamic acid and sulphocarbamic acid are known only in their esters. Dithiocarbamic acid may be obtained by decomposition of its ammonium salt, which is produced by the action of ammonia in alcoholic solution upon carbon disulphide: CS 2 +2NH 3 =S :C ^^ HJ Similarly, the amine salts of the alkyl-dithiocarbamic acids are formed by the action of the primary amines upon carbon disulphide. Thiourea is obtained by heating ammonium isothiocyanate : S:C:N(NH 4 )=S:C\^H 2 2 , as urea is obtained from the isocyanate. It is also formed by the action of hydrogen sulphide upon cyanamide : H 2 S+CN.NH 2 =S :C <^H 2 . It is decomposed by boiling acids or alkalies into C0 2 , NH 3 , and H 2 S. It forms salts, and alkyl, phenyl and acidyl derivatives similar to those of urea. By addition with alkyl halides thiourea forms salts of alkyl thiopseudoureas, corresponding to pseudourea, which are used in certain cyclic syntheses: H 2 N.CS.NH 2 +C 2 H 5 C1=:HN :C COMPOUND UREAS. These compounds, which are exceedingly numerous, may be con- sidered as derived from urea by the substitution of one or more alcoholic or acid radicals for hydrogen atoms. Those containing alcoholic radicals, alkyl ureas, such as ethyl urea, CK)\jJg!c,H,' are obtained: (1) By the action of primary or secondary amines upon isocyanic esters: NH 2 .C 2 H 5 +0 :C :N.C 2 H 5 =CO : (NH.C 2 H 5 ) 2 (2) By heating the isocyanic esters with water, the amines and carbonic acid being formed as intermediate products: OC :N.C 2 H 5 +H 2 0=NH 2 .C 2 H 5 +C0 2 , and OC :N.C 2 H 5 +NH 2 .C 2 H 5 =CO : (NH.C 2 H 5 ) 2 (3) By condensation of amines with urea chloride. Those containing acid radicals have received the distinctive name of ureides. Of these, some are monureides, derived from a single COMPOUND UREAS 317 molecule t)f urea, others diureides, derived from two molecules. Some of the monurei'des are open chain compounds, but the most impor- tant of them, and all the diurei'des except carbonyl diurea are cyclic compounds, derivatives of glyoxalin, pyrimidin or cyanidin. Thus CH 2 OH there are two ureides, corresponding to glyeollic acid, | : one, COOH hydantoic acid, an open chain urei'de : CO \NHCH COOH the other, /NH.CH 2 hydantoin, a cyclic compound: CO \NH.CO Only the acyclic ureides will be here considered, the cyclic ones will be referred to as derivatives of their parent substances. The monacidyl monurei'des, containing a single acidyl, are formed by the action of acidyl chlorides or anhydrides upon urea. Thus acetyl-urea is ob- tained with acetyl chloride: CH 3 .CO.C1+NH 2 .CO.NH 2 =H 2 N.CO.NH ( CO.CH 3 ) -f HC1 or with acetic anhydride: ( CO.CH 3 ) 2 ,0+2NH 2 .CO.NH 2 =2NH 2 .CO.NH ( CO.CH 3 ) -f H 2 O. Mixed ureides, containing an alkyl and an acidyl, are formed in like manner from alkyl-ureas. Thus methyl-urea and acetyl chloride form methyl- acetyl-urea : CH 3 .NH.CO.NH 2 -f CH 3 .CO.C1=:CH 3 .NH.CO.NH ( CO.CH 3 ) -f HC1 Such mixed ureides are also formed by the action of bromine and potassium hydroxide upon the amides, by reactions comparable with those which produce the monamines (p. 294). Thus methyl-acetyl-urea is formed from acetamide: 2CH 3 .CO.NH 2 +Br 2 +2KOH=CH 3 .HN.CO.NH (CO.CH 3 ) -(-2KBr-|-2H 2 The diacidyl-urei'des are formed by the action of phosgene (carbonyl chloride) upon the amides. Thus acetamide yields diacetyl-urea : 2CH 3 .CO.NH 2 -f COC1 2 = ( CH 3 .CO ) HN.CO.NH ( CH 3 .CO ) -f 2HC1 Allophanic acid H 2 N.CO.NH.COOH the. simplest ef the acyclic monu- rei'des, is that of carbonic acid, HO.CO.OH, and is known only in its esters. Biuret H 2 N.CO.NH.CO.NH 2 is both the amide of allophanic acid, and the monurei'de of carbamic acid, H 2 N.CO.OH. It is formed by heating the allophanic esters with ammonia : H 2 N.CO.NH.COO(C 2 H 5 )+NH 3 =H 2 N.CO.NH.CO.NH 2 + CH 3 .CH 2 OH By condensation of urea and carbamic acid: H 2 N.CO.NH 2 +HO.CO.NH 2 =H 2 N.CO.NH.CO.NH 2 +H 2 And by heating urea to about 150 : 2H 2 N.CO.NH 2 =H 2 N.CO.NH.CO.NH 2 +NH 3 When further heated it is itself decomposed to cyanuric acid and ammonia : 3C 2 H 5 N 3 2 =2C 3 H 3 N 3 3 +3NH 8 318 TEXT-BOOK OF CHEMISTRY It forms crystals, soluble in water, f. p. 190. It is chiefly of interest in connection with the biuret reaction, which consists in the formation of a red-violet liquid when biuret is heated with a dilute solution of CuS0 4 alkalinized with KOH (see Fehling's test). The reaction is due to the formation of a compound, Cu[NH 2 (OH).CO.- NH.CO.NH 2 (OH)K] 2 , which has been obtained in red crystals. Or NiS0 4 may be used in place of CuS0 4 , in which case an orange colored liquid is produced. The biuret reaction is given by many substances other than biuret, such as malonamide, oxamide, aspartic diamide, albumins, albumoses, peptones, etc., and is considered to be proof of the presence in the substance giving it of two amido-carbonyl groups, CONH 2 , attached to each other, or to N or C, as in : CONH 2 /CONH 2 /CONH 2 HN H 2 C CONH 2 \CONH, \CONH 3 Oxamide. Biuret. Malonamide. The reaction is also given by glycocol amide and sarcosine amide, which contain the grouping: H 2 N.CH 2 .CO.NH 2 . Hydantoi'c AcidGlycoluric Acid H 2 N.CO.NH.CH 2 .COOH the next su- perior homologue of allophanic acid, is the acyclic monurei'de of glycollic acid, CH 2 OH.COOH, and is obtained as its Ba salt by hydration of the corresponding cyclic monureide, hydantoin, by BaH 2 O 2 . (p. 395). It is also formed by con- densation of urea and amido acetic acid at 120: H 2 N.CO.NH 2 -f-CH 2 NH 2 .COOH=H 2 N.CO.NH.CH 2 .COOH+NH 3 Oxaluric Acid H 2 N.CO.NH.CO.COOH is the acyclic monureide of oxalic acid, and is obtained in its salts by hydration of those of the cyclic monureide, oxalylurea. The free acid is a white, crystalline powder, sparingly soluble in water. It is easily further hydrolyzed to urea and oxalic acid by heating with alkalies, or even with water. Its ammonium salts exist in the urine in small amount. Carbonyl Diurea H 2 N.CO.NH.CO.HN.CO.NH 2 the only acyclic diureide, is formed by the union of two urea molecules, with loss of H 2 , by the carbonyl group, brought about by the action of carbonyl chloride upon urea: 2H 2 N.CO.NH 2 -|-COC1 2 =CO ( HN.CO.NH 2 ) 2 +2HCl. It is a sparingly soluble, crystalline powder, which is split by heat into cyanuric acid and ammonia: C 3 H NA=C 3 H 3 N 8 3 +NH 3 Imides are compounds derivable either by substitution of an acidyleno for H 2 in a single NH 3 molecule, or by substitution of the imide group, NH, for (OH) 2 in the carboxyls of a dicarboxylic acid. They are obtained by the com- plete dehydration of the ammonium salts of the acids, or similarly from the amic acids (see pp. 312, 313). Thus monoammonic succinate, or succinamic acid yields succinimide: CH 2 .COOH CH 2 .CO\ CH 2 .COOH CH 2 .CO\ NH+2H 2 0, or I NH-fH,0 CH 2 .COO(NHJ CH 2 .CO/ CH 2 .CONH 2 CH 2 CO/ The imides, therefore, except carbimide, corresponding lo carbonic acid, which is isocyanic acid, O:C:N.H (p. 307), are heterocyclic compounds. The imides, NITROGEN DERIVATIVES OP ALCOHOLS, ETC. 319 when acted upon by alkalies or baryta water, produce the salts of the amic acids. Thus succinimide and caustic potash form potassium succinamate. NITROGEN DERIVATIVES OF ALCOHOLS, ALDEHYDES AND KETONES. Nitro derivatives of the alcohols, aldehydes, and ketones in which the N0 2 is substituted for OH or for 0, such as CH 3 .CH 2 (N0 2 ) and CH 3 .CH(N0 2 ) 2 and CH 3 C(N0 2 ) 2 .CH 3 are mono- or dinitro-paraffins. Besides these, nitro alcohols are also known, in which the N0 2 is substituted in a hydrocarbon group, e.g., nitro-ethyl alcohol, CH 2 (N0 2 ).CH 2 OH. Amido-alcohols, such as amido-ethyl alcohol, or oxethylamine, CH 2 (NH 2 ).CH 2 OH, may also be considered as derived from the glycols by substitution of NH 2 for OH. These are the oxyamines, hydroxamines, hydramines, or oxyamine bases, among which are choline and neurine. Aldehyde-ammonia Ethidene Jiydroxamine CH 3 .CH \^H isomeric with ethylene hydroxamine, CH 2 (NH 2 ).CH 2 OH, may be considered as an amido-ethyl alcohol in which the NH 2 is substituted for H in the methoxyl group, CH 3 .CH(NH 2 )OH. It is obtained by the action of dry NH 3 upon an ethereal solution of acetic aldehyde: CH 3 .CHO+NH 3 =CH 3 .CH(NH 2 )OH. It is a crystalline solid, spar- ingly soluble in water, alkaline, f. p. 80. The corresponding compound derivable from formic aldehyde: H.CH(NH 2 )OH, is not known; but when formaldehyde and ammonia react hexamethylene tetramine, (CH 2 ) 6 N 4 , is produced: 6H.CHO+ 4NH 3 =(CH 2 ) 6 N 4 +6H 2 0. This is a crystalline solid, very soluble in water, which decomposes when heated, and behaves as a monacid base. It is decomposed by weak acids and by acid salts, in the reverse manner to its formation, with liberation of formic aldehyde, a reaction which is probably caused by the acid sodium phosphate of the urine, and explains its action as a urinary antiseptic, for which purpose it is used under the names formin and urotropin. Amido aldehydes, such as amido acetaldehyde, CH 2 (NH 2 ).CHO, are also known. Acetonamines The action of ammonia upon acetone causes a condensation of two or three molecules of acetone with one of ammo- C*TT 0*O C*TT\ nia, with formation of diacetonamine : 3 '( C j^ 2 //C.NH 2 , a colorless / C*TT C 1 / OTT \ \ liquid; and triacetonamine : OC^Q-^'Q JQ-^j^/NH, a crystalline solid, f. p. 40. Triacetonamine and its relative vinyl diacetonamine are derivatives of piperidine, and are the nuclei of the artificial local anesthetics OL and fi eucaine. Alkyl derivatives of these are formed when amines are used in place of ammonia. Amido acetones, or amido ketones, such as CH 3 .CO.CH 2 (NH 2 ), amido acetone, are also known. 320 TEXT-BOOK OF CHEMISTRY Aldoximes, and ketoximes or acetoximes are isomeric compounds derivable from the aldehydes and ketones by substitution of the oxime group, =N.OH, for oxygen. As the aldehydes and ketones are derivatives of formic aldehyde by substitution of alkyls for H, so the aldoximes and ketoximes are referable to carboxime, the oxime of formic aldehyde: OC v. -r O\j v TT \jyj v PITT \1 \-tl \Uri 3 Formaldehyde. Acetaldehyde. Dimethyl ketone. \H Carboxime. Aldoxime. Ketoxime. They are formed by the action of hydroxylamine upon aldehydes or ketones in alkaline solution, the aldoximes more readily than the ketoximes. Thus acetaldoxime is obtained from acetic aldehyde: CH 3 .CHO+HONH 2 =CH 3 .CH :NOH+H 2 and acetoxime from dimethyl ketone: CH 3 .CO.CH 3 +HONH 2 =CH 3 .C (NOH) .CH 3 +H 2 The aldoximes are colorless liquids, miscible with water; the ketoximes crystalline solids, soluble in water. Nascent hydrogen reduces both aldoximes and ketoximes to amines, those from the aldoximes being amines of primary alcohols and those from the ketoximes, amines of secondary alcohols : CH 3 .CH :NOH+2H 2 =CH 3 .CH 2 NH 2 +H 2 0, and CH 3 .C (NOH) .CH 3 +2H 2 =CH 3 .CHNH 2 .CH 3 +H 2 These reactions constitute a general method for obtaining amines (pp. 294, 296). Both aldoximes and ketoximes are hydrolyzed to their parent substances by boiling with acids: CH 3 .CH :NOH+H 2 0=CH 3 .CHO+HONH 2 , and CH 3 .C(NOH).CH 3 +H 2 0=CH 3 .CO.CH 3 +HONH 2 The principal difference between aliphatic aldoximes and ke- toximes is in their behavior towards acidyl halides and anhydrides, with which the former produce nitriles, and the latter esters. Thus with acetaldoxime : CH 3 .CH :NOH+CH 3 .COC1=CH 3 .CN+CH 3 .COOH+HC1, or CH 3 .CH:NOH+(CH 3 CO) 2 0=CH 3 .CN+2CH 3 .COOH; and with acetoxime: ( CH 3 ) 2 C :NOH+CH 3 .COC1=CH 3 .COO [N :C : ( CH 3 ) 2 ] +HC1, or (CH 3 ) 2 C:NOH+(CH 3 .CO) 2 0=:CH 3 .COO[N:C:(CH 3 ) 2 ] +CH 3 .COOH Acetyl chloride and anhydride cause atomic rearrangement with NITROGEN DERIVATIVES OF ACIDS 321 acyclic and some higher aliphatic ketoximes, to form, phenyl or alkyl amidea: c c .|>C:NOH= CH C fc H d >NH. Aldehyde hydrazones and ketone hydrazones are compounds cor- responding to the aldoximes and ketoximes, formed by condensation of the aldehydes and ketones with phenylhydrazine (p. 379), the bivalent remainder of which, =N.NH.C 6 H 5 , is substituted for oxygen. They are obtained by the action of phenylhydrazine upon the alde- hyde or ketone in ethereal solutions: CH 3 .CHO+H 2 N.NH.C 6 H 5 =CH 3 .CH : (N.NH.C 6 H 5 ) +H 2 0, or (CH 3 ) 2 :CO+H 2 N.NH.C 6 H 5 = (CH 3 ) 2 :C :(N.NH.C 6 H 5 ) +H 2 NITROGEN DERIVATIVES OF ACIDS. The nitrogen derivatives of the pure carboxylic acids are numer- ous and varied. They may be divided into two classes: (1) Those in which nitrogen or a nitrogen-containing group is substituted in the carboxyl for OOH or for OH, and (2) those in which the substitution is in a hydrocarbon group. The first class includes the nitriles, amidines, hydroxamic acids, amidoximes, nitrolic acids and amides, which have already been considered, and the hydrazides, which are compounds bearing the same relation to the hydrazines (p. 302) that the amides do to the amines. The following are included in the second class : Nitro-acids, such as nitro-acetic acid, CH 2 (N0 2 ).COOH, are un- stable compounds, usually existing only in their esters and salts. Monamido-acids are much more stable, and include a number of substances of physiological interest. They are derived from the fatty acids by substitution of one NH 2 for a hydrogen atom in a hydrocar- bon group. In this position the attachment of the amido group is much firmer than it is in the primary monamides in which it replaces the hydroxyl. The amides are easily converted into ammonium salts by boiling water: H 2 N.CO.CH 3 +H 2 0=CH 3 .COO (NHJ while the amido acids are not acted upon. From the pure carboxylic acids, amic acids (p. 313), or amides (p. 311) amido-acids are derivable by substitution of HN 2 for OH or for H : CH 3 CH 3 CH 2 (NH 2 ) COOH CO(NH 2 ) COOH Acetic acid. Acetamide. Amido-acetic acid. COOH CO(NH 2 ) CO(NH 2 ) COOH CH 2 CH 2 CH 2 CH 2 (NH 2 ) I I ! I COOH COO(C 2 H 5 ) CO(NH 2 ) COOH Malonic acid. Malonamic ester. Malonamide. Amido-malonic acid. 322 TEXT-BOOK OF CHEMISTRY From the monocarboxylic oxyacids, oxy amides are derived by substitution of NH 2 for OH in COOH ; amido-acids of the same series by its substitution for H in a hydrocarbon group ; and amido- acids of the acetic series by its substitution for OH in a CHOH or a CH 2 OH group : CH, CH 2 OH CH 8 CHOH CH 2 CHOH COOH COOH CO(NH 2 ) a oxy prop ionic oxypropionic Lactamide (lactic) acid. (hydracrylic) acid. (oxyamide). CH 2 (NH 2 ) CH, CH 2 (NH 2 ) CHOH *CH(NH 3 ) CH 2 COOH COOH COOH Amldo-lactlc a amido-propionic ft amido-propionic acid. acid. acid. The first amido-acid of the fatty series, amido-formic acid, NH 2 .CO.OH, is carbamic acid. The third and superior terms of the series form place isomeres, according to the position of the NH 2 group, corresponding to the oxyacids and similarly designated as a, /?, 7, etc., or 1-, 2-, 3-, etc. Those acids in which the NH 2 is not attached to the terminal C atom contain an asymmetric C*, and therefore exist in optical isomeres. The fatty amido-acids are also known as glycocolls or alanines. They are obtained: (1) By the action of ammonia upon the monochloro acids. Thus amido-acetic acid is obtained from monochloracetic acid : CH 2 C1.COOH+NH 3 =CH 2 (NH 2 ) .COOH+HC1. (2) By reduction of the nitro acids. Thus nitroacetic ester, CH 2 (NO,).COO.C 2 H 5 , yields amido-acetic ester. (3) By the action of nascent hydrogen upon the cyan-fatty acids: CN.COOH+2H 2 =CH 2 (NH 2 ).COOH (4) By hydrolysis by HC1 of the nitriles of the a amido-acids: CH 3 .CHNH 2 .CN+2H 2 0=CH 3 .CHNH 2 .COOH+NH 3 This method permits of the formation of the amido-acids from the corresponding alcohols, through the aldehydes. The amido-acids are crystalline solids, most of which are sweet in taste, soluble in water, insoluble in alcohol or in ether, neutral in reaction. As they contain both amido and carboxyl groups, they have both basic and acid functions. With acids they form ammonium salts. They form stable metallic salts with bases, but their esters are unstable. The esters retain their basic function and form more stable hydrochlorides. Stable compounds are, however, produced by NITROGEN DERIVATIVES OF ACIDS 323 the replacement of their amido hydrogen, either by acidyls or by alkyls. The acidyl compounds, such as aeetyl amido-acetic acid, CH 2 .NH(C 2 H 3 0).COOH, are formed by the action of acidyl chlorides upon the amido-acids ; and the alkyl derivatives, such as methyl gly- cocoll, CH 2 .NH(CH 3 ).COOH, by the action of amines upon haloid fatty acids. On dehydration the amido-acids behave like the oxy- acids, which are also both basic and acid. The a acids on dehydra- tion yield cyclic anhydrides, which are ketopiperazines and which on hydration yield, not two molecules of the acid, but a dipeptide. The y and 8 acids yield cyclic esters, called lactams, corresponding to the lactones. The resemblance of these compounds is shown by the fol- lowing formula?: CH 2 .NH 2 CH 2 .NH.CO CH 2 .OH CH 2 COO COOH CO.NH.CH 2 COOH COO CH 2 Amido-acetic Glycocoll Glycollic Glycollide acid. anhydride. acid. (lactide.) CH 2 NH 2 CH 2 NH CH 2 .OH CH 2 CH 2 CH 2 CH 2 in 2 COOH CO CH 2 CH 2 CH 3 CH 2 COOH COO , Y amido-butyric y butyro- Y oxy-butyric -y butyro- acid. lactam. acid. lactone. The formation of the lactams is another instance of the pro- duction of closed chain from open chain compounds. By dry distillation the amido acids are split to amines and carbon dioxide : CH 2 NH 2 .COOH=CH 3 .NH 2 +C0 2 When heated with hydriodic acid at 200 they are reduced to fatty acids : CH 2 NH 2 .COOH+H 2 =CH 3 .COOH+NH 3 Amido acids of the acetic and oxalic series are converted into the corresponding monochlor acid by nitrosyl chloride: CH 2 NH 2 .COOH+NOC1=CH 2 C1.COOH+N 2 +H 2 Nitrous acid acts upon the <*-amido acids according to the re- action characteristic of the amido group converting them into oxy- acids, with evolution of free nitrogen : CH 2 NH 2 .COOH+HN0 2 =CH 2 OH.COOH+N 2 +H 2 This conversion of amido into oxyacids, which probably occurs in the animal organism, is referred to as deamidation. Amido-acetic Acid Glycocoll Glycine Glycolamic acid Gela- tin sugar CH 2 .NH 2 .COOH was first obtained by the action of 324 TEXT-BOOK OF CHEMISTRY H 2 S0 4 upon gelatin. It is formed by the action of KOH upon glue ; and, synthetically, by the methods given above and by the union of formic aldehyde, hydrocyanic acid and water: H.CHO+HCN+H 2 0=CH 2 (NH 2 ).COOH It is produced along with benzoic acid, in the decomposition of hippuric acid (p. 375) ; as a product of decomposition of glycocholic acid; and by the action of hydriodic acid upon uric acid (p. 406). It occurs uncombined in the muscle of the scallop. It appears as large, colorless, transparent crystals; has a sweet taste; fuses at 170; sparingly soluble in cold water; much more soluble in warm water; insoluble in absolute alcohol and in ether. It forms crystalline salts with acids, which are decomposed at a boiling temperature. Nitric acid oxidizes it to glycollic acid. It is very resistant to oxidation by KMn0 4 in acid solution, but in alkaline solution or in its esters it is readily oxidized to urea: 2CH 2 NH 2 .COOH+30 2 =H 2 N.CO.NH 2 +3C0 2 +3H 2 from which it is presumed that the free acid does not exist as such, but as a lactam. Its acid function is more marked; it expels carbonic and acetic acids from calcium carbonate and lead acetate. It dissolves cupric hydroxide in alkaline solution, and there is no re- duction on boiling the solution; but on addition of alcohol to the cold solution, blue crystalline needles of copper glycolamate separate. With ferric chloride it gives an intense red color, which is discharged by acids, and restored by ammonia. With phenol and sodium hypo- chlorite it gives a blue color, as does ammonia. It forms esters and amides. Its methylic ester is isomeric with sarcosine. Heated under pressure with benzoic acid it forms hippuric acid. Fused with urea it forms glycolylurea and, ultimately, uric acid. Methyl-glycocoll Sarcosine CH 2 .NH(CH 3 ).COOH -- isomeric with alanine, the methyl ester of glycocoll, and lactamide, is not known to exist as such in animal nature, but it may be obtained from creatine by the action of barium hydroxide: + H 2 = CH 2 .NH(CH,).COOH4-H 2 N.CO.NH 2 It is formed by the action of methylamine upon monochloracetic acid : CH 2 C1.COOH+CH 3 .H 2 N=CH 2 .NH(CH 3 ).COOH+HC1. 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 forms salts with acids, but it is not known to form metallic salts. It unites with cyanamide to form creatine; and with cyanogen chloride to form methylhy- dantoine. NITROGEN DERIVATIVES OF ACIDS 325 Amido-propionic Acids Alanines Two are known: a alanine, CH 3 . CH(NH 2 ).COOH, formed by the reduction of a nitroso-propionic acid; and /3 alanine, CH 2 (NH 2 ) .CH 2 .COOH, formed either by the reduction of /3 nitroso- propionic acid, or by the action of ammonia upon /3 iodo-propionic acid. Neither is known to exist in nature. Nitrous acid converts the two alanines into the corresponding lactic acids. Amido-butyric Acids C 4 H 9 N0 2 and Amido-valeric acids CglT^NG^ are mainly of theoretic interest. Alpha amido-n-valeric acid, CH 3 .CH 2 .CH 2 .- CH(NH 2 ).COOH, is a product of oxidation of coni'ine. Alpha amido-iso-valeric ac id Butalanine, ( CH 3 ) 2 : CH.CHNH 2 .COOH occurs in the pancreas, and is formed as a product of decomposition of fibrin and of certain proteins. Amido-caproic Acids Leucines. Twenty-seven isomeric amido acids are derivable from the seven caproic acids; and this number is still further increased by the fact that in many of these the intro- duction of the amido group renders a carbon atom asymmetric (see formula of a amido-propionic acid, p. 322). The leucine, which is of physiological interest as a product of decomposition of the proteins, is the laevo a amido-isobutyl-acetic acid, (CH 3 ) 2 :CH.CH 2 .*CH (NH 2 ).COOH, as is demonstrated by its synthetic formation from isovaleric aldehyde, (CH 3 ) 2 :CH.CH 2 .CHO: 2(CH 3 ) 2 .CH.CH 2 .CH 2 OH+0 2 =2(CH 3 ) 2 .CH.CH 2 .CHO+2H 2 (CH 3 ) 2 :CH.CH 2 .CHO+CN.NH 4 = (CH 3 ) 2 :CH.CEUCHNH 2 .- CN+H 2 (CH 3 ) 2 :CH.CH 2 .CHNH 2 .CN+2H 9 O^(CH 3 ) 2 :CH.CH 2 .- CHNH 2 .COOH+NH 2 The corresponding dextro-acid has been obtained by the action of Penicillium glaucum upon the inactive acid; and the Ia3vo-acid, known as "vegetable leucine" from the vegetable globulin, conglutin. f^TT \ d-isoleucine methyl-ethyl-tf -amido propionic acid c 2 nl/~ CH.CHNH 2 .COOH is also a product of hydrolysis of proteins, and is formed synthetically by the same methods as leucine, starting with secondary butyl carbinol CH.CH 2 OH. "Animal leucine" is produced, accompanied by tyrosine, in the decomposition of proteins by boiling with dilute acids or alkalies, by fusion with caustic alkalies, by putrefaction, and by trypsin diges- tion. It appears to exist also as a normal constituent of the pancreas, spleen, thymus, lymphatic and salivary glands, liver and kidneys. Pathologically the quantity of leucine is much increased in the liver in diseases of that organ, in typhus and in variola; in the bile in typhus ; in the blood in leukemia, and in yellow atrophy of the liver ; in the urine in yellow atrophy of the liver, in typhus, in variola, and in phosphorus poisoning; in choleraic discharges from the intestine; in pus ; in the fluids of dropsy and of atheromatous cysts. Leucine crystallizes from alcohol in soft, pearly plates, lighter than water, and somewhat resembling cholesterol; sometimes in 326 TEXT-BOOK OF CHEMISTRY rounded masses of closely grouped, radiating needles. Pure leucine is sparingly soluble in water, almost insoluble in alcohol and ether, but readily soluble in hot water or alcohol. When impure it is more soluble. It io odorless and tasteless, and its solutions are neutral. It dissolves readily in acids and alkalies, forming crystalline com- pounds with the former. It fuses and sublimes at 170 without de- composition, but at a slightly higher temperature is decomposed into amylamine and carbon dioxide. When heated with hydriodic acid under pressure the leucines are decomposed into ammonia and the corresponding caproic acids. By nitrous acid they are oxidized to the corresponding oxycaproic, or leucic acids, C 6 H 12 3 , with elimination of water and of nitrogen. Hot solutions of leucine form precipitates with hot solutions of cupric acetate. They dissolve cupric hydroxide, but do not reduce it on boiling. When boiled with solution of neutral lead ace- tate and carefully neutralized with ammonia, they deposit brilliant crystals of a compound of leucine and lead oxide. When HN0 3 is slowly evaporated in contact with leucine on platinum foil a colorless residue remains, which, when warmed with NaOH solution, turns yellow or brown, and on further concentration, forms oily drops, which do not adhere to the platinum (Scherer's reaction). Solution of leucine, when heated with solution of mercurous nitrate, liberates metallic mercury (Hofmeister's reaction). PHOSPHORUS, ANTIMONY, AND ARSENIC DERIVATIVES. Many organic compounds, similar to those containing nitrogen, in which that element is replaced by phosphorus, antimony, or arsenic, are known. Of these only a few arsenic derivatives require mention. Dimethyl Arsine (CH 3 ) 2 HAs corresponding to dimethyl amine, (CH 3 ) 2 HN, is a colorless liquid, having an intensely dis- agreeable odor, which ignites spontaneously in air. It may be con- sidered as the hydride of a radical, (CH 3 ) 2 As, which, from the dis- agreeable odor and intensely poisonous action of all of its com- pounds, has received the name cacodyl. As the amines are considered as derived from ammonia by substitution of alkyl groups for the hydrogen, so the compounds of which this is a type are derived from the corresponding hydrogen compounds of phosphorus, antimony, and arsenic, and are called phosphines, stibines, and arsines. The parent substance of the arseno-organic compounds is a fuming, foul-smelling liquid, obtained by distilling a mixture of arsenic trioxide and potassium acetate, and called fuming liquid of Cadet. The principal constituent of this is cacodyl oxide, or alkar- sine, (CHj'la/ ' a liquid which boils at 120, insoluble in water, soluble in alcohol and in ether. Cacodyl, or dicacodyl, (CH 3 ) 2 As.- As(CH 3 ) 2 is a colorless, insoluble liquid, which boils at 170 and UNSATURATED ALIPHATIC COMPOUNDS 327 ignites spontaneously in air. Cacodyl and most of its compounds are exceedingly poisonous, especially the cyanide (CH 3 ) 2 .As(CN), an ethereal, volatile liquid the presence of whose vapor in air, even in minute traces, produces symptoms referable both to arsenic and to cyanogen. Probably minute quantities of arsines are formed during the putrefaction of cadavers embalmed with arsenical liquids. Cacodylic acid (CH 3 ) 2 :As.O.OH. is formed by oxidation of cacodyl oxide by HgO in presence of water: ( CHJ ;ls> 0+2HgO+H 2 0=2 ( CH 3 ) 2 As.OOH+Hg 2 It is easily soluble in water; it is acid, odorless, and crystallizes in prisms. It is not attacked by nitric acid or even by aqua regia. Its salts are soluble in water and crystallize with difficulty. Its Na salt is used in medicine. UNSATURATED ALIPHATIC COMPOUNDS. In this class are included all open chain carbon compounds in which two carbon atoms exchange more than one valence (p. 197). As the saturated compounds consist of the members of the first, or methane, series of hydrocarbons and their derivatives, so the un- saturated compounds are the remaining series of open chain hydro- carbons and their unsaturated derivatives (p. 201). HYDROCARBONS, ETHENE, OR OLEFINE SERIES. The members of this series contain two atoms of carbon less than the corresponding terms of the methane series. They may be modi- fied by addition, behaving as bivalent radicals, as well as by substitu- tion. Their "Geneva" names terminate in ene. Ethene Ethylene Olefiant gasOlefineElaylC'H. 2 :C~K 2 is formed by the dry distillation of fats, resins, wood, and coal, and is a valuable constituent of illuminating gas. It is formed synthetically: (1) By heating a mixture of alcohol, H 2 S0 4 and sand. In this reaction ethyl-sulphuric acid is formed and decomposed : C 2 H 5 .HSO^=H 2 S0 4 +CH 2 :CH 2 (2) By the action of caustic potash upon ethyl bromide: CH 3 .CH 2 Br+KOH=KBr+H 2 0+CH 2 :CH 2 (3) By heating together acetylene and hydrogen, or by the action of nascent hydrogen upon copper acetylide: CHiCH+H 2 =CH 2 :CH 2 , or C 2 Cu 2 +2H 2 =CH 2 :CH 2 +2Cu (4) By heating methylene iodide with copper: 2CH 2 I 2 +2Cu:=CH 2 :CH 2 +2CuI 2 328 TEXT-BOOK OF CHEMISTRY (5) By the action of sodium, of zinc or of magnesium upon ethylene bichloride or bibromide: CH 2 Cl.CH 2 Cl+Na 2 =CH 2 :CH 2 +2NaCl, or CH 2 Br.CH 2 Br+Zn=CH 2 :CH 2 -fZnBr 2 , or CH 2 Br :CH 2 Br+Mg=MgBr 2 +CH 2 :CH 2 It is a colorless gas, tasteless, has a faint odor of salt water, spar- ingly soluble in water. Its critical temperature is 13; its critical pressure 60 atmospheres. It boils at 105. It burns with luminous flame, and forms explosive mixtures with air. By long contact with a red-hot surface it is decomposed into acetylene, methane, ethane, a tarry product, and carbon. It unites with hydrogen to form ethane, C 2 H 6 ; with oxygen it unites explo- sively on approach of flame, to form carbon dioxide and water. It combines with hydrobromic and hydriodic acids to form ethyl bromide, C 2 H 5 Br, and ethyl iodide, C 2 H 5 I. It combines with sul- phuric acid to form ethyl-sulphuric acid: CH 2 :CH 2 -}-H 2 S0 4 = C 2 H 5 .HS0 4 . Mixtures of ethene and chlorine explode, with copious deposition of carbon, on approach of flame. In diffuse daylight they unite slowly, with separation of an oily liquid, ethylene chloride, or Dutch liquid, CH 2 C1.CH 2 C1, to whose formation the name "olefiant gas" is due. The same compound is formed when ethene is passed through a mixture of Mn0 2 , NaCl, H 2 S0 4 , and H 2 0. When passed through alkaline solution of potassium permanganate, it is oxidized to oxalic acid and water: 2CH 2 :CH 2 +50 2 =2COOH.COOH+2H 2 Or, by careful oxidation by dilute solution of the same agent, it forms ethene glycol: 2CH 2 :CH 2 +2H 2 0+0 2 =2CH 2 OH.CH 2 OH (p. 222). When inhaled, diluted with air, ethene produces effects some- what similar to those of nitrous oxide. Two groupings of (C 2 H 4 )" are possible, CH 2 .CH 2 , and CH 3 .CH=, the former produced by the breaking of the double bond between the carbon atoms in ethene, the latter by double substitution in ethane. Compounds containing the grouping CH 2 .CH 2 are designated as ethylene or ethene compounds, e.g., ethylene chloride, C1CH 2 .CH 2 C1, b. p. 84, those containing the grouping CH 3 .CH= are called ethidene or ethylidene compounds, e.g., ethidene chloride, CH 3 .CHC1 2 , b. p. 58. Homologues of Ethene. The superior homologues of ethene exist in coal gas and coal tar. They are formed by the methods 1 and 2, used for the preparation of ethene, but starting from the cor- responding superior monoatomic alcohol. The lower terms are gas- eous, the higher liquid at the ordinary temperature. They undergo reactions similar to those of ethene, and in addition, readily poly- UNSATURATED ALIPHATIC COMPOUNDS 329 merize under the influence of sulphuric acid, zinc chloride and other substances. ETHINE, OR ACETYLENE SERIES. Acetylene Ethine HCiCH exists in coal gas, and is formed in the decomposition by heat or otherwise, of many organic sub- stances. It is formed: (1) By passing an electric arc in an atmos- phere of hydrogen : 2C+H 2 =CHiCH This is the only known synthesis of a hydrocarbon directly from the elements. (2) By the action of water upon calcium carbide: C 2 Ca+2H 2 0=HCiCH+CaH 2 2 This method is used industrially for the preparation of acetylene for use as an illuminating gas. (3) By heating chloroform, bromoform or iodoform with sodium, copper, silver or zinc: 2CHCl 3 +3Na 2 =6NaCl-fHCiCH (4) By heating ethylene bromide with caustic potash. The re- action occurs in two phases, vinyl bromide being formed as an inter- mediate product : CH 2 Br.CH 2 Br+KOH=CHBr :CH 2 +KBr+H 2 0, and CHBr :CH 2 +KOH=CH:CH+KBr+H 2 Acetylene is a colorless gas, rather soluble in water, having a peculiar, disagreeable odor, that which is observed when a Bunsen burner burns within the tube. This gas contains as impurities com- pounds of S, P, and Si, which must be removed if it is to be used indoors. It is liquefied by a pressure of 48 atmospheres at 0. It forms explosive mixtures with air or oxygen. In contact with a red- hot surface, and in absence of air, it polymerizes to benzene 3C 2 H 2 = C 6 H 6 , an action which accounts for the presence of benzene in gas tar, and which is of great interest in connection with the relations between the open chain and the closed compounds. Nascent hydrogen converts acetylene into ethene, C 2 H 4 , and then into ethane, C 2 H 6 . Under the influence of the electric discharge, it combines with nitro- gen to form hydrocyanic acid : C 2 H 2 +N 2 =2CNH. It combines with HC1 and with HI to form ethidene chloride, CH 3 .CHC1 2 , or iodide, CH 3 .CHI 2 . Mixed with chlorine it detonates violently in diffuse day- light. The hydrogen atoms of acetylene may be replaced by metals to form acetylides, or carbides. Sodium and calcium acetylides are stable at high temperatures, but are decomposed by water with for- mation of acetylene. Silver and copper acetylides are highly ex- plosive when dry, and explosions which have occurred when illumi- 330 TEXT-BOOK OF CHEMISTRY nating gas was in contact with brass or copper were probably due to the formation of the latter. The formation of copper acetylide, which separates as a blood-red precipitate when acetylene is con- ducted through a solution of cuprous chloride, is utilized as a test for the presence of acetylene. Acetylene mercuric chloride, C 2 (HgCl) 2 , separates as a non-explosive, white precipitate when acetylene is passed through a solution of mercuric chloride. DIOLEFINE AND SUPERIOR SERIES. The diolefines are isomeric with the hydrocarbons of the acetylene series, containing two double linkages, in place of one triple linkage. Thus allene, or allylene, CH 2 :C:CH 2 , is isomeric with propine, or propylene, CH|C.CH 3 . Trimethyl-ethylene Pentene Amylene Valerene ( CH 3 ) 2 : C : CH.CH 3 is a colorless, mobile liquid, boiling at 39, obtained by heating alcohol with a con- centrated solution of zinc chloride. It is used as an anesthetic, and in the preparation of tertiary amylic alcohol. UNSATURATED OXIDATION PRODUCTS OF UNSATURATED HYDROCARBONS. Like the paraffins, the defines, acetylenes, diolefines, etc., yield alcohols, aldehydes, ketones, acids, oxides, and esters. Allyl Alcohol CH 2 :CH.CH 2 OH is formed: ( 1 ) By the action of sodium upon dichlorhydrine : CH 2 C1.CHC1.CH 2 OH+ Na 2 =CH 2 : CH.CH 2 OH+2NaCl (2) By heating allyl iodide with water: CH 2 : CH.CHJ+ H 2 0=CH 2 : CH.CH 2 OH+HI (3) By reduction of acroleln by nascent hydrogen: CH 2 : CH.CHO+H 2 =CH 2 : CH.CH 2 OH (4) By heating glycerol with formic acid, which first forms a glycerol ester, which then splits to allylic alcohol, carbon dioxide and water: CH 2 OH.CHOH.CH 2 ( OOC.H ) =CH 2 OH.CH : CH 2 -f CO 2 +H 2 Oxalic acid, which yields formic acid, may be used in place of the latter. It is a colorless, mobile liquid, solidifies at 50, boils at 97, sp. gr. 0.8507 at 25, soluble in water, has an odor resembling the combined odors of alcohol and essence of mustard, burns with a luminous flame. It is isomeric with propylic aldehyde and with acetone. Oxidizing agents, such as silver oxide, convert it first into the corresponding aldehyde, acroleme, then into the acid, acrylic acid. It does not unite readily with hydrogen, but, in presence of nascent H, union takes place slowly, with formation of normal propyl alcohol. It forms products of addition with chlorine, bromine, and iodine, similar to those derived from glycerol. Acrylic Aldehyde Acroleine CH 2 : CH.CHO the first of the series of olcfine aldehydes, is the substance which causes the disagreeable odor developed when fats or oils are overheated. It is formed: (1) By oxidation of allylic alcohol; (2) by distilling glycerol with strong H 2 S0 4 or with KHS0 4 : CII 2 OH.CHOH.CH 2 OH=CH 2 : CH.CHO+2H 2 O Acroleine is a colorless liquid, having a pungent odor, and giving off a vapor which is intensely irritating; sp. gr. 0.841 at 20, boils at 52, soluble UNSATURATED ALIPHATIC COMPOUNDS 331 in 2-3 parts of water. Oxidizing agents convert it into acrylic acid. Nascent hydrogen reduces it to allyl alcohol. It does not combine with alkaline bisul- phites. It reduces ammoniacal silver nitrate solution as does acetic aldehyde. It suffers change even when kept in closed vessels, and deposits a white, flocculent material, which is called disacryl, while formic, acetic and acrylic acids are also produced. Oleic Acids. The acids of this series are monocarboxylic acids derived from the defines, and contain two atoms of hydrogen less than the corresponding terms of the acetic series. They are formed : (1) By oxidation of their corresponding alcohols or aldehydes. Thus allylic alcohol, CH 2 :CH.CH 2 OH, or acroleine, CH 2 :CH.CHO, yields acrylic acid, CH 2 :CH.COOH. (2) By the action of alcoholic KOH upon the monohalogen fatty acids. Thus ft monobromo propionic acid yields acrylic acid: CH 2 Br.CH 2 .COOH+KOH=CH 2 :CH.COOH+KBr+H 2 (3) By dehydration of acids of the oxy acetic series. Thus ethy- lene lactic acid forms acrylic acid when heated: CH 2 OH.CH 2 .COOH=CH 2 :CH.COOH+H 2 (4) From the allyl halides, by conversion into cyanides and saponification. Thus crotonic acid is obtained from allyl iodide: CH 2 :CH.CH 2 I+KCN=CH 2 :CH.CH 2 CN+KI, and CH 2 :CH.CH 2 CN+2H 2 0+HC1=CH 2 :CH.CH 2 .COOH+NH 4 C1 The oleic acids combine with the hydracids to form monohalogen fatty acids, the halogen assuming the position furthest removed from the carboxyl. Thus acrylic acid and hydriodic acid form ft iodo propionic acid: CH 2 :CH.COOH+HI=CH 2 I.CH 2 .COOH Heated with caustic alkalies to 100, they form oxyacids. Thus acrylic acid forms lactic acid: CH 2 :CH.COOH+KOH=CH 3 .CHOH.COOK But, when fused with caustic alkalies, they are decomposed into fatty acids, with loss of H. Thus acrylic acid yields formic and acetic acids : CH 2 :CH.COOH+2KOH=H.COOK+CH 3 .COOK+H 2 The fty acids, i.e., those in which the double bond is between the ft and y positions, as in ethidene propionic acid, CH 3 .CH:CH.CH 2 . COOH, when heated with H 2 S0 4 form lactones. Acrylic Acid CH 2 :CH.COOH is best obtained by oxidizing acroleine with silver oxide. It is a liquid below 7, boils at 140, mixes with water, and has an odor like that of acetic acid. Oleic Acid CH 8 .(CH 2 ) 7 .CH:CH.(CH 2 ) 7 .COOH exists as its glyceric ester in fats and fixed oils, and is obtained in an impure 332 TEXT-BOOK OF CHEMISTRY form, on a large scale, as a by-product in the manufacture of stearin candles. Pure oleic acid is a white, pearly, crystalline solid, fuses at 14, odorless, tasteless, soluble in alcohol and in ether, insoluble in water, sp. gr. 0.808 at 19, and neutral in reaction. Exposed to air, the liquid acid absorbs oxygen, and becomes yellow, rancid in taste and odor, acid in reaction, and incapable of solidification on cooling. Nitric acid oxidizes it, with formation of the lower fatty acids and sebacic acid, C 10 H 18 4 . Heated to 200 with excess of caustic potash, it is split into palmitic and acetic acids: C 18 H 3 A+2KOH=C 10 H 31 2 K+C 2 H 3 2 K+H 2 The oleates of the alkaline metals are soft, soluble soaps; those of the earthy metals are insoluble in water. The action of iodine and of bromine upon oleic acid is utilized in the analysis of fats and oils. At the ordinary temperature the fatty acids, including palmitic and stearic, are not affected by iodine, but the double bond in oleic acid is broken, and one molecule of oleic acid combines with two atoms of iodine. Under like conditions each molecule of linoleic acid takes up four atoms of iodine. The amount of iodine which a given weight of a fat or oil can combine with will increase with its tenure of oleic, or, particularly, of linoleic acid. ' ' Hubl 's iodine number " of a fat or oil is the quantity of iodine which 100 grams of the sub- stance can take up under the conditions of the process and is an important factor for its identification. Elaidic Acid C n H 33 .COOH is an isomere of oleic acid, produced from it by the action of nitrous acid. It is a crystalline solid, fusible at 51. Its for- mation is utilized to distinguish non-drying from drying oils (p. 282). The former, containing oleic acid, solidify when acted on by nitrous acid; the latter, containing linoleic acid, do not. Olefine dicarboxylic Acids. The acids of this series contain two atoms of hydrogen less than the corresponding acids of the oxalic series, and they con- sequently bear the same relation to those acids that the acids of the oleic series bear to those of the acetic series. Esters of three acids having the composition C 2 H 2 (COOH) 2 are known. The free acid corresponding to one of these, methylene malonic ester, CH 2 : C S QQQ | 2 jj 5 j , is not known. The other two, fumaric and maleic acids, are "space isomerides " (p. 238). Fumaric acid is considered to have the axial H.C.OOH symmetric structure: , because it does not yield an anhydride, HOOC.C.H and because, on oxidation, it yields racemic acid, while maleic acid has the plane symmetrical structure, because, owing to the closer proximity of the carboxyls, H.C.COOH H.C.CO\ , it readily forms an anhydride, 0, and because on oxidation H.C.COOH H.C.CO/ it yields inactive, or meso-tartaric acid (see p. 239 and Fig. 18, ibid.). Fumaric acid exists free in many plants, notably in Iceland moss. Fumaric and maleTc acids are readily converted one into the other by simple heating, UNSATURATED ALIPHATIC COMPOUNDS 333 and the two are produced together by the action of heat upon malic acid, or by boiling solutions of monobromo-succinic acid. Fumaric acid crystallizes in small prisms, almost insoluble in cold water, which sublimes at 200. Male'ic acid fuses at 130, and boils at 160. Both fumaric and male'ic acids are converted into succinic acid by nascent hydrogen. Allyl Oxide Allylic ether ( CH 2 : CH.CH 2 ) 2 is an example of the un- saturated ethers. It exists in small quantity in crude essence of garlic, and is formed by the action of allyl iodide upon sodium-allyl oxide. It is a colorless liquid, having the odor of garlic, insoluble in water, boiling at 82. Mixed ethers are also known, such as propargyl ethyl ether, CH;C.CH 2 .O.CH 2 .CH 8 .- UNSATURATED SULPHUR AND NITROGEN COMPOUNDS. Allyl Sulphide (CH 2 :CH.CH 2 ) 2 S corresponding to the oxide, is the prin- cipal constituent of volatile oil of garlic, obtained by distilling garlic with water. It is formed by the action of alcoholic solution of potassium sulphide upon allyl iodide. It is a colorless oil, lighter than water, soluble in alcohol and in ether, boils at 140. Allyl Isothiocyanate Mustard oil S:C:N.CH 2 .CH:CH 2 is the chief con- stituent of volatile oil of mustard, and of radish oil. It is prepared artificially by distilling allyl bromide or iodide with potassium or silver thiocyanate: S : C : N. Ag-f-CH 2 LCH : CH 2 =S : C : N.CH 2 .CH : CH z -f Agl It does not exist preformed in the mustard seeds, but is produced by the de- composition of a glucoside, potassium myronate, in the presence of water under the influence of an enzyme, also contained in the seeds, called myrosin. The action takes place at 0, but not at temperatures above 40. The activity of myrosin is also impaired by the presence of acetic acid (vinegar). The pungent, rubefacient and vesicant actions of mustard are due to mustard oil. Pure allyl isothiocyanate is a colorless oil, sp. gr. 1.015 at 20, boils at 150, has a penetrating, pungent odor, sparingly soluble in water, very soluble in alcohol and in ether. Exposed to air it gradually turns brownish-yellow, and deposits a resinoid material. Heated with HC1 or with H 2 O, it is decomposed into carbon dioxide, hydrogen sulphide and allyl-amine: S : C : N.CH 2 .CH : CH 2 +2H 2 0=C0 2 -f SH 2 +NH 2 .CH 2 .CH : CH 2 334 TEXT-BOOK OF CHEMISTRY CLOSED CHAIN, AROMATIC OR CYCLIC COMPOUNDS. These compounds, which include many important natural prod- ucts, and a practically unlimited number of synthetic compounds, differ from the members of the open chain series in that they contain a group of more than two atoms united together by exchange of valences in such a manner as to form a closed chain, or ring, or nucleus. If all the atoms so united are carbon atoms the substance belongs to the carbocyclic class; if an element other than carbon enters into the formation of the ring the substance is heterocyclic. Some closed chain compounds are produced by the interaction of two open chain compounds, as in the formation of certain diamines (p. 296) and compound ureas (p. 316). Others, such as the lactides (p. 283), lactones (p. 283), and lactams (p. 323), are produced by internal reaction in an open chain molecule. But the principal method of formation of closed chain compounds is by polymerization. In some cases this takes place at comparatively low temperatures, as in the formation of trioxymethylene from formaldehyde (p. 228), and of the polymeric thioaldehydes and their sulphones (p. 284). Among the instances of formation of cyclic from acyclic com- pounds there is one of polymerization at a high temperature which is of special interest as bearing upon the constitution of the cyclic compounds. The central figure of the carbocyclic compounds is benzene, C H 6 , which is obtained principally from gas-tar. Coal gas contains acetylene, C 2 H 2 , and it is easy to conceive that one or two of the bonds uniting the two carbon atoms in acetylene may be loosened under the influence of heat, and that a molecule of benzene may be produced by fusion of three molecules of acetylene : 3C 2 H 2 = C 6 H 6 . The product so obtained is neither dipropargyl, HC:C.CH 2 .- CH 2 .C;CH, nor dimethyl diacetylene, H 3 C.CiC.C:C.CH 3 , but another substance, the nature of whose substituted derivatives indicates that the six hydrogen atoms are of equal value, and therefore similarly attached to carbon atoms; and, there being three bisubstituted deriva- tives (p. 337), to at least three different carbon atoms. These con- ditions can only be fulfilled by a cyclic structure of the molecule of benzene and its derivatives (p. 336). Pyridine also, which has a prominence among the heterocyclic compounds corresponding to that of benzene among the carbocyclic, has been obtained from acetylene and hydrocyanic acid by a fusion very similar to that by which acetylene alone forms benzene: 2C 2 H 2 +HCN=C 5 H 5 N. It is also formed by the action of heat upon substances containing nitrogen as well as carbon. CARBOCYCLIC COMPOUNDS 335 CARBOCYCLIC COMPOUNDS. Carbocyclic compounds are known containing from three to seven carbon atoms in a ring. Compounds are also known containing a much larger number of carbon atoms, but these are formed by fusion or union of two or more rings of six carbon atoms or less, or by the attachment of an open chain grouping upon a closed chain one (p. 340). The hexacarbocyclic compounds are far more numerous and important than the others. The mononuclear carbocyclic hydrocarbons have algebraic for- mula varying from CnH2 to CnH2_6, and are isomeric with the un- saturated open chain hydrocarbons (p. 201). Those of the series CnR2n are known as polymethylenes, being considered as formed by the union of a number of methylene groups, CH 2 . Thus hexahydro- benzene is hexamethylene, CH 2 /^j'^\CH 2 . But the chemical relations of the polymethylenes to the saturated hydrocarbons is closer than that to their isomeres, the olefines, because, containing no double linkages, they cannot be modified by addition without disrup- tion of the ring. So long as the cyclic formation is maintained, the polymethylenes are saturated compounds, as are the paraffins. For this reason their "Geneva" names are the same as those of the paraf- fins of like carbon content, to which is prefixed the syllable " cycle," and they are known generically as cycloparaffins ; or the symbol R is used in place of the syllable "cyclo." The hydrocarbons of the series CnH2-2, isomeric with the acetylenes and diolefines, are refer- able to the latter, not to the former, as they cannot contain a triple linkage in the ring. But, containing only one double linkage, they are more closely related to the olefines. Therefore tetrahydrobenzene, CH \CH 2 :^) CH 2> isomeric with hexadiene, CH 2 :CH.CH 2 .CH 2 .CH> CH 2 , containing but one double linkage, is cyclo-hexene, or R- hexene. Similarly dihydrobenzene, CH/^ 2 -^ 2 ^CH, is a cyclo- diolefine : R-hexadiene ; and benzene a cyclotriolefine : R-hexatriene. The cycloparaffins are formed by the action of sodium upon the dibromoparaffins. Thus trimethylene is obtained from trimethylene bromide : /CH 2 CH 2 Br.CH 2 .CH 2 Br+Na 2 =CH 2 I +2NaBr \CH 2 Tri-, tetra-, penta-, and hepta-carbocyclic hydrocarbons, and their numerous derivatives, notably acids and ketones, are known. They are not as yet, however, of medical interest, except that certain tetra-, and penta-compounds are among the decomposition products of certain alkaloids. 336 TEXT-BOOK OF CHEMISTRY HEXACARBOCYCLIC COMPOUNDS AROMATIC SUBSTANCES. These compounds, which are very numerous and important, all contain a group of six carbon atoms, to which are attached six, eight, ten or twelve univalents, or their equivalent. As the simplest repre- sentative of the class is benzene, C 6 H 6 , and as all of these bodies may be derived from benzene, directly or indirectly, and yield that hydro- carbon on decomposition, the aromatic substances may be considered as derivatives of benzene. This being the case, the constitution of benzene itself is of great importance, and has been the subject of much study. Several schematic representations of the structure of the benzene molecule have been suggested, the most demonstrative of which are the hexagonal form of Kekule, the prismatic form of Ladenburg, and the diagonal form of Claus : H H H J, _ J, H A H C C H J L A H C / C C H O H Hexagonal. Prismatic. Diagonal. In the hexagonal formula the carbon atoms exchange one and two valences alternately, each being attached to two others; in the pris- matic form each carbon atom is attached to three others by single valences; and in the diagonal form the hexagon is retained, but, in place of double linkages, a central linkage between all the carbon atoms is substituted. All of these formulas represent the equivalence of the carbon atoms, and the constitution of isomeres equally well (see below). The prismatic formula cannot be modified to represent a constitution of the additive derivatives of benzene, such as dihydro- benzene, CH^g|'f')CH, and tetrahydrobenzene, CH{^^)CH r Neither the prismatic nor the diagonal formula admits double link- ages between carbon atoms in the ring. That these exist is shown, however, by the formation of the additive products mentioned, by the formation of anhydrides from ortho-derivatives only (see below), and by certain physical properties. Moreover, the hexagonal formula ac- HEXACARBOCYCLIC COMPOUNDS 337 cords well with the tetrahedral representation of the valences of the carbon atom (p. 239), the six tetrahedra being alternately united by edges and apexes in benzene, and by apexes in hexahydrobenzene. For these (and other) reasons, chemists have very generally adopted the hexagonal expression, although it still leaves something to be desired. The figure of a hexagon is used in chemical writings to rep- resent the benzene ring. If used alone it represents a molecule of benzene, C G H 6 ; and to represent the products of substitution the sym- bols of the substituted group are written in the proper position, thus: COOH Benzene. Benzole acid. Dlhydrobenzene. CO Plithalic anhydride. Isomerism of Benzene Substitution Products. (1) The six atoms of hydrogen in benzene are of equal value. There exists but one mono-substituted derivative of benzene containing any given univalent: one chlorobenzene, C 6 H 5 C1, one nitro-benzene, C 6 H 5 (N0 2 ), one amido-benzene, C 6 H 5 (NH 2 ), one benzoic acid, C 6 H 5 .COOH, etc. Therefore, benzene is symmetrical in structure, and its hydrogen atoms equal each other in value, as do those of methane, while those of pyridine (p. 000) are not all of like value. 2. Any hydrogen atom selected in the benzene ring is symmetri- cally placed in reference to two pairs of hydrogen atoms, and to the sixth hydrogen atom individually. With all di-, tri-, and tetra-substi- tuted derivatives of benzene, containing like substituted univalents, there are three isomeres. Three dichloro-, three trichloro-, and three tetrachloro-benzenes, etc., and in no instance are more than three known. There is but one explanation of the facts mentioned above, namely, that the different bi-, tri-, and tetra-derivatives are pro- duced by differences in the relative positions of the substituted groups, by differences in " orientation," as among the aliphatic com- pounds, the several oxyacids are " place isomeres " of each other (p. 260). The hexagonal formula of benzene is very convenient for showing the structure of the several isomeres. For this purpose the carbon atoms are numbered, beginning, for convenience, at the top and proceeding clockwise. It has been demonstrated that in some of the bisubsti- tuted derivatives the two substituted groups are attached to adjacent carbon atoms, i.e., to 1-2, 2-3, 3-4, 4-5, 5-6, or 6-1. Clearly for each carbon atom there is a pair of adjacent positions, as 338 TEXT-BOOK OF CHEMISTRY 1-2 and 1-6, 2-1 and 2-3, etc., which are equivalent to each other.* In other bisubstituted derivatives it may be shown that the two substituted groups are attached to carbon atoms, separated from each other by one carbon atom on one side and by three on the other, an arrangement which renders the hexagon unsymmetrical. Such posi- tions are 1-3, 2-4, 3-5, 4-6, 5-1, and 6-2. Or, for each carbon atom there is a pair of equivalent unsymmetrical positions, as 1-3 and 1-5, etc. There remains but one other arrangement possible, the sym- metrical, or diagonal, 1-4, 2-5, 3-6. With the tri- and tetra-substi- tuted derivatives there are also three possible arrangements : the adja- cent, vicinal, or consecutive, as 1-2-3, 2-3-4 ; 1-2-3-4, or 2-3-4-5 ; the unsymmetrical, as 1-2-4, 3-4-6; 1-2-3-5, or 3-4-5-1; and the symmetrical, as 1-3-5, 2-4-6; 1-2-4-5, or 3-4-6-1. Compounds in which the substitution is adjacent are designated as ortho-com- pounds, or, in writing, by the abbreviation o-, or by the figures 1-2, etc. Thus C 6 H 4 (OH) 2(1 _ 2) , o-diphenol. Unsymmetrical com- pounds are designated as meta-compounds, or, abbreviated, m-, or by the figures, 1-3, etc.; e.g., C 6 H 3 (Br) 3(1 . 24) , m-tribromobenzene. Sym- metrical compounds are designated as para-compounds, abbreviated p-, or 1-4, etc.: e.g., C 6 H 2 (NH 2 ) 4(1 . 24 ^ ) , p-tetraamido-benzene. Or, to illustrate by the formulae of the di- and tetra-chlorobenzenes : 1-2-3-5 Unsymmetrical. Meta. In the bisubstituted derivatives it is immaterial whether the two substituted groups are of the same kind or different. But when, in a trisubstituted derivative, the substituted groups are not the same Note. The principal objection to the hexagonal formula of benzene (and stated by K<-kule himself) is that these two positions are not entirely equivalent, as in the position 1-2 (lie grouping Is=C C=, while in 1-6 It is C=C , and that consequently there should b> t\v. ortho derivatives, while but one Is known. The student is referred to more extended works for a discussion of this subject. HEXACARBOCYCLIC COMPOUNDS 339 in kind, the number of possible isomeres is increased. Thus there are six possible chloro-dibromobenzenes (formulae 1 to 6 below), of which two (1 and 2) are derived from orthodibromobenzene, C 6 H 4 :- Br 2 three (3, 4, and 5) from metadibromobenzene, C 6 H 4 :Br 2(1 3) 1) and one (6) from paradibromobenzene, C 6 H 4 Br 2(1 4) The number of possible trisubstituted derivatives is increased to ten when all three substituted groups are of different kind. Orthodibromo- metachloro. Orthodibromo- parachloro. Metadlbromo- orthochloro. OH (NO,) Metadibromo- allometachloro. Paradibroino- metachloro. In naming these derivatives, the characterizing group of the parent substance is given the position 1 in the hexagon, the prefix " ortho " is applied to the name of the group occupying one of the ortho positions 2 and 6, " 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 formula 7 above is orthonitro-meta- bromo-phenol. But another substance is known, not identical with this, having the formula 8 above, in which the nitro group occupies the second ortho position, 6. To distinguish substances such as these, the designation " allortho " is given to the position 6, and the designation " allometa " to the position 5. Thus the substance having the formula 8 is metabromo-allorthonitro-phenol. When formulae are used the numerals corresponding to the position of substitution, enclosed in brackets, are placed after the symbols. Thus 7 is writ- ten: C H 3 (OH)(N0 2 ) [8] Br [3J , and 8: C 6 H 3 (OH)Br |31 (N0 2 ) L6] Classification of Aromatic Substances. The benzene derivatives may be classified into five classes : A. Compounds containing a single benzene nucleus, unmodified except by substitution for hydrogen. Monobenzenic compounds. In- 340 TEXT-BOOK OF CHEMISTRY eludes benzene and its homologues, and the phenols, alcohols, acids, etc., derived from them. B. Compounds containing a single benzene nucleus in which one (or more) of the double bonds has been converted into a single one, thus adding two, four, or six valences to the carbon ring. Monohy- drobenzenic compounds. Includes the cyclohexadienes, cyclohexenes, and cyclohexanes (p. 335), and their derivatives, among which are the terpenes and camphors. C. Compounds containing two (or more) benzene nuclei, or ben- zene and pentacarbocyclic rings, fused together, and having two car- bon atoms in common. Includes indene, fluorene, naphthalene, an- thracene, and phenanthrene and their derivatives. Compounds with condensed nuclei. D. Compounds containing two (or more) benzene rings, directly united by loss of two H atoms. Diphenyl and its derivatives. E. Compounds containing two (or more) benzene nuclei, united by aliphatic groups. Includes di- and polyphenyl paraffins, olefines ^and acetylenes and their derivatives. The following formulas will serve to indicate the differences in constitution of the several classes: CH, H 2 H H A a i i //\ /\ //\ /\\ H C C H H 2 C CH 2 H C C C OH H C C-H H 2 C CH a H C C C H \\/ \/ \\/ \// C C C C A I A ^ (A) (B) (C) Methyl-benzene. Hexahydrobenzene. j8 Naphthol. HHHH HH HH u an( ^ they also resemble each other in that each is only slowly and imperfectly esteri- fied when heated to 150 with acetic acid. But, while the tertiary alcohols are readily attacked by phosphorus pentachloride, with for- mation of alkyl chlorides: ( CH 3 ) 3 !C.OH+PC1 5 = ( CH 3 ) 3 :-C.Cl+POCl 3 +HCl that reagent displaces the hydroxyl of the phenols only im- perfectly, or not at all. The products of the reaction with phenol are either phenyl phosphoric tetrachloride : C 6 H 5 .OH+PC1 5 :=C 6 H 5 .OPC1 4 +HC1 or a mixture of monochlorobenzene with either diphenyl phos- phoric acid : 4C 6 H 5 .OH+PC1 5 =2C 6 H 5 C1+P0 4 H(C 6 H 5 ) 2 +3HC1, or triphenyl phosphate: 4C 6 H 5 .OH+PC1 5 =C 6 H 5 C1+P0 4 ( C 6 H 5 ) 3 +4HCl The latter alone is produced by the action of phosphorus oxy- chloride on phenol: 3C 6 H 5 .OH-f POC1 3 =P0 4 ( C 6 H 5 ) 3 +3HCl The phenols occur in nature in small quantities only ; some in the vegetable world, and some in combination as ester sulphuric acid in the urine. They are mostly products of distillation of wood, coal, etc. MONOATOMIC MONOHYDRIC PHENOLS. The monoatomic phenols are produced: (1) by fusing the cor- responding sulphonic acids with caustic alkali: C 6 H 5 .S0 3 K+KOH=C 6 H 5 .OH+K 2 S0 3 PHENOLS 345 (2) By decomposition of the diazo-compounds by boiling with water : C 6 H 5 .N:N.HS0 4 +H 2 0=C 6 H 5 .OH+N 2 +H 2 SO, (3) The higher phenols are produced by heating phenol with ZnCl 2 and the alcohols, a phenolic ether being also formed. Thus phenol and methylic alcohol yield cresol and methyl-phenyl ether : 2C 6 H 5 .OH+2H.CH 2 OH=C 6 H 4 .OH.CH 3 +C 6 H 5 .O.CH 3 +2H 2 (4) The phenyl magnesium halides are oxidized by passing air through their ethereal solutions with the formation of compounds of this type: R.O.Mg.X, which when hydrolyzed yield phenols: C 6 H 5 .O.Mg.Br+H 2 0=C 6 H 5 OH+HO.Mg.Br. The phenols are reduced to hydrocarbons by heating with zinc dust. Their ring-hydrogen is readily replaceable by other elements or groups to form haloid, nitro, amido derivatives, etc. Their hy- droxyl hydrogen is also readily replaceable by alkyls to produce ethers, by Na, K, and Ca to produce phenates, and by acidyls to pro- duce phenyl esters. The phenols combine with the diazo-compounds to produce azo- and diazo dyes, and with phthalic acid to produce phthalems. Phenol Benzophenol Phenyl hydroxide Phenic acid Car- bolic acid C 6 H 5 .OH exists in considerable quantity in coal- and wood-tar, and in small quantity in castoreum and, in combination, in the urine. It is produced in the intestine. It is formed: (1) by fusing sodium-phenyl sulphide with excess of alkali: C 6 H 5 NaS+NaOH=C 6 H 5 .OH+Na 2 S (2) By heating phenyl iodide and potassium hydroxide at 320: C 6 H 5 I+KOH=C G H 5 .OH+KI (3) By heating together salicylic acid and quicklime: C 6 H 4 .OH.COOH+Ca(OH) 2 =C 6 H 5 .OH+CaC0 3 +H 2 (4) By total synthesis from acetylene, through benzene, and its sulphonic acid. (5) By decomposition of the phenylic esters by alkalies. Thus salol yields phenol and salicylic acid: C 6 H 4 .OH.COO(C 6 H 5 )+KOH=C 6 H 5 .OH+C 6 H 4 .OH.COOK (6) By dry distillation of benzoin. " Synthetic phenol," prepared by method (4), is now manu- factured. "Carbolic acid" is obtained from the "middle oil" of gas tar (p. 341). It is purified by conversion into potassium phenate, C,.H 5 .OK, which is crystallized, decomposed by HC1, and the liberated phenol recrystallized and distilled. 346 TEXT-BOOK OF CHEMISTRY Phenol is extensively used, not only as an antiseptic, but also in the manufacture of numerous derivatives, including medicinal com- pounds, dyes and explosives. Phenol crystallizes in long, colorless needles, fuses at 43, boils at 183, sp. gr. 1.084 at 0, has a characteristic odor, and an acrid, burning taste, soluble in 15 parts of water at 20, very soluble in alcohol and in ether, neutral in reaction. It may be distilled without decomposition. Its vapor is reduced to benzene by heating with Zn. It combines with H 2 S0 4 to form o-, and p-phenol sulphonic acids. With HN0 3 it forms 2-4-6-trinitrophenol. Heated with sulphuric and oxalic or arsenic acid, it yields several triphenyl-methane dyes, among which are corallin, rosolic acid, peonin, azulin, aurin, and phenicin. Analytical Characters (1) Its peculiar odor. (2) Mix with one quarter volume of NH 4 OH ; add two drops of sodium hypochlorite solution, and warm: a blue or green color. Add HC1 to acid reac- tion: turns red. (3) Add two drops of the liquid to a little HC1, and then a drop of HN0 3 : a purple red color. (4) Boil with HN0 3 so long as red fumes are given off; neutralize with KOH: a yellow, crystalline precipitate. (5) Heat with Millon's reagent: a yellow ppt, forming a red solution in HN0 3 . (6) With solution of FeS0 4 : a lilac color. (7) Add excess of bromine water: a yellowish-white pre- cipitate. This compound, tribromophenol, C 6 H 2 Br 3 OH, is the form in which phenol is quantitatively determined; 100 parts of it cor- respond to 29.8 parts of phenol. (8) Moisten a pine shaving with the liquid, then with HC1, to which a trace of KC10 3 has been added im- mediately before use, and expose to sunlight : a fine blue color. The test should be tried also with a solution of phenol, and with the acid alone, as only certain varieties of pine are suitable. Toxicology. Carbolic acid is an active poison and corrosive. It has caused death in a dose of 1.5 gram. The average duration of fatal cases is 2-8 hours. Death may occur in 3-5 minutes from collapse. It causes a burning sensation, soon followed by intense pain and cauterization of all parts with which it comes in contact. The stain which it produces is at first white, after a few minutes; later it turns darker and, when the eschar separates, a brown stain remains, which persists for many days. Vomiting usually occurs, the vomited matters, as well as the breath, having the odor of carbolic acid. The patient soon becomes unconscious, and death is from collapse or in coma. The urine, normal in color when first voided, soon becomes olive-green, brown, or even black in color. The treatment consists in administration of albumin, saccharated lime, sodium sulphate, or strong alcohol, followed by lavage. Phenates. Carbolates. The hydroxyl hydrogen of phenol is re- placeable by certain metals and by alkyls to form phenates and phenyl ethers. When phenol and KOH are heated together, potas- sium phenate, C 6 H 5 OK, is formed. This, when treated in alcoholic solution with HgCl 2 , produces mercuric phenate, (C 6 H 5 0) 2 Hg, a yellow, crystalline solid which has been used in medicine. PHENOLS 347 Phenol Esters. The H of the OH of phenol is replaceable by either alkyls or acidyls. With the former phenol plays the part of an acid, and therefore the resulting compounds are the phenol esters, corresponding to the metallic phenates. But, although phenol is not an alcohol, the radical phenyl (C 6 H 5 )' of which it is the hydroxide, is in all respects equivalent to the alkyls, of which the monohydric alco- hols are the hydroxides. Therefore the phenol esters, such as C 6 H 5 .- O.CH 3 , are also the phenyl ethers (p. 360). The phenyl esters, on the other hand, may be considered as derivable from phenol by substitu- tion of acidyls for hydroxyl hydrogen: C 6 H 5 .0.(OC.CH 3 ), or as derivable from the acids by substitution of phenyl for carboxyl hydro- gen: CH 3 .COO(C 6 H 5 ). The phenyl esters are formed by the action of the acidyl chlorides upon the phenols, or upon their metallic derivatives : C 6 H n .OH+CH 3 .COCl=CH 3 .C0 2 .C 6 H 5 +HCl, or C 6 H 5 .OK+CH 3 .COC1=CH 3 .C0 2 .C 6 H 5 +KC1 as the aliphatic esters are formed by the action of acidyl halides upon the alcohols or upon the alcoholates. Cresols Cresylols Cresylic acids Benzylic or cresylic phe- nols C 6 H 4 <^Qg 3 108. Of the three possible compounds, two, the para and ortho, accompany phenol in coal-tar, from which they may be separated by fractional distillation. They are more readily ob- tained pure from toluene. Creolin an antiseptic less poisonous than phenol, consists chiefly of cresols. Lysol is impure paracresol, mixed with fat and saponified. Creosote Creosotum (U. S. P.) is a complex mixture contain- ing phenol, cresol, creasol, C 8 H 10 2 , guaiacol, C 7 H 8 2 (see pyro- catechol), and other substances, obtained from wood-tar, and formerly extensively used as an antiseptic. It is an oily liquid, colorless when freshly prepared, but becoming brownish on exposure to light. It has a burning taste and a strong, peculiar odor. It boils at 203, and does not solidify at 27. Xenols Xylenols. Theoretically there are six possible xenols which are dimethyl phenols, C 6 H 3 ( CH 3 ) 2 OH ; two derivable from orthoxylene, three from metaxylene and one from paraxylene. They have all been produced synthetically. There are also three possible xenols which are ethyl phenols, C 6 H 4 ( C 2 H 5 ) OH. Thymol 3-Methyl-6-isopropyl phenol Cymylic phenol C 6 H 3 (OH) (1) - (CH 3 )( 3 ) (C 3 H 7 )( 6 ), exists, accompanying cymene and thymene, C 10 H J6 , in essence of thyme, from which it is obtained. It is also prepared synthetically from cuminic aldehyde, C 6 H 4 (CHO) ( i) (C 3 H 7 ) r4) . It crystallizes in large, transparent, rhombohedral tables; has a peppery taste, and an agreeable, aromatic odor. It fuses at 44, and boils at 230; 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 deodorizing and antiseptic agent, possessing the advantage over phenol of having itself a pleasant odor. 348 TEXT-BOOK OF CHEMISTRY Aristol is diiodo-thymol, a dibenzenic compound, produced by the action of a solution of I in KI upon an aqueous solution of thymol in the presence of KOH. It is an inodorous, yellowish-red powder, insoluble in H 2 O, very spar- ingly soluble in alcohol, readily soluble in ether and in chloroform. It is decomposed by heat and by light and is said to be a non-poisonous antiseptic. Carvacrol 2-Methyl-5-isopropyl phenol C 8 H 3 ( OH ) a) ( CH 3 ) (2) ( C 3 H 7 ) (5) _ an isomere of thymol, exists in many essential oils, and is obtained by the action of iodine upon camphor; by the action of potash in fusion upon cymene sulphonic acid, C 10 H 13 SO 3 H; or by a transposition of the atoms of another isomere, carvol, which exists in caraway oil. It is an oil, boiling at 233-235. Heated with P 2 O 6 , it yields orthocresol. SUBSTITUTED PHENOLS. Phenol is a monosubstituted derivative, and hence still contains five H atoms which may be replaced by other elements or radicals, to produce di- or tri- or poly-substituted derivatives of benzene, which will be ortho, meta or para,, etc., according to the relations of the introduced groups to the OH, already existing in phenol, or to the CH2n + i and OH groups in its superior homologues. Chlorophenols. The three monochlorinated compounds are ob- tainable from the corresponding chloranilines. Orthochlorophenol (1 2) is a colorless liquid, boils at 175-176, converted into pyro- catechol by KOH. Metachlorophenol (1 3) is a liquid, boiling at 214. KOH converts it into resorcinol. Parachlorophenol (1 4) is a crystalline solid, fusible at 37, converted into quinol by fusion with KOH. Di-, tri-, and penta-chlorophenols are also known. Bromophenols correspond in method of formation and properties with the Cl derivatives. 2-4-6 Tribromophenol C 6 H 2 .OH.Br 3 is the precipitate formed on adding bromine water to phenol solution. It forms white crystals, fusing at 92, insoluble in water, soluble in alcohol and ether. It has been used as an antiseptic in diphtheria under the name Bromol. lodophenols are formed by the action of iodine and K 2 S upon phenol in the presence of excess of alkali, or from the corresponding amidophenols. Like the chlorine and bromine derivatives, they yield the corresponding diphenol by the action of KOH in fusion. A tri- iodophenol, formed by the action of solution of I in K 2 S upon an alkaline solution of phenol, has been proposed as a substitute for iodoform under the name annidalin. For nitro- and amido-phenols, see pp. 369, 373. DIATOMIC, OR DIHYDRIC PHENOLS. Diatomic phenols are derived from the benzenic hydrocarbons by the substitution of two (OH) groups for two atoms of hydrogen. In obedience to the laws of substitution already discussed, three such compounds exist, corresponding to each hydrocarbon. PHENOLS 349 Pyrocatechol Pyrocatechin Oxyphenic add Or ttiodioxy -ben- zene C 6 H 4 (OH) 2 d-2) is obtained from catechin or from morintannic acid by dry distillation; also by the action of KOH on orthochlor- or orthoiodo-phenol, or by decomposing its methyl ether, guaiacol, by HI at 200. It crystallizes in short, square prisms; fuses at 104, and boils at 245.5. Readily soluble in water, alcohol, and ether. Its aqueous solution gives a dark green color with FeCl 3 solution, changing to violet on addition of NH 4 OH, NaHC0 3 , or tartaric acid. Its acid sulphuric ester exists in the urine. Monomethy 1-pyrocatechuic Ether Guaiacol C 6 H 4 .OH. (OCH 3 ) (2) exists in beech-wood tar, from which an impure (60- 90%) guaiacol is obtained as a yellowish liquid, sp. gr. 1.133, boiling at 206-207, by distillation. Pure guaiacol is obtained from this by crystallization at low temperature; by heating pyrocatechol with potassium-methyl sulphate and KOH; also from vanillin, and from veratrol. It is a crystalline solid, fuses at 33, boils at 205, soluble in 50 parts of water. Guaiacol has been used in the treatment of phthisis both on account of its germicidal action, and upon the theory that it forms compounds with the toxalbumins, which are readily eliminated. It is also used in numerous forms of combination: in its carbonic esters, as styracol=cinnamyl-guaiacol, as benzosol= benzoyl-guaiacol, as thiocol=guaiacol-potassium sulphonate, and in combination with salicylic acid. Dimethyl-pyrocatechuic Ether Veratrol C 6 H 4 ( OCH 3 ) 2 (1 . 2) is an oil, crystallizing at 15, formed by distilling veratric acid, or by acting upon the potassium salt of guaiacol with methyl iodide. Resorcinol Resorcin Metadioxy -benzene C 6 H 4 (OH) 2(1 ?) , is ob- tained by the action of fused KOE on metachlor-, or iodophenol. It is also prepared by dry distillation of extract of Brazil wood. It forms short, thick, colorless and odorless, rhombic prisms. Fuses at 104, and boils at 271. It is very soluble in water, alcohol, and ether. Its aqueous solution is neutral in reaction, and intensely sweet. With FeCl 3 its solutions assume a dark- violet color, which is discharged by NH 4 OH. Its ammoniacal solution by exposure to air, assumes a pink color, changing to brown and, on evaporation, green and dark blue. Heated with phthalic anhydride at 195 it yields fluoresceme. It dissolves in fuming H 2 S0 4 , forming an orange-red solution, which becomes darker, changes to greenish-black, then to pure blue, and finally to purple on being warmed. Resorcinol, heated with sodium nitrite and H 2 to about 150 yields a blue pigment known as lacmoid, which behaves like litmus with acids and alkalies, but is more sensitive. Quinol Hydroquinone Paradioxy-benzene C 6 H 4 (OH) 2 (1 4) is formed by fusing paraiodo-phenol with KOH at 180, by dry dis- tillation of oxysalicylic acid or of quinic acid, and by the action of reducing agents on quinone. It forms colorless, rhombic prisms, 350 TEXT-BOOK OF CHEMISTRY which fuse at 169. Readily soluble in water, alcohol, or ether. Its aqueous solution is turned red-brown by NH 4 OH. Oxidizing agents convert it into quinone. TRIATOMIC, OR TRIHYDRIC PHENOLS. Phloroglucin C H 3 ( OH ) 3 (1 3 5) is obtained by the action of potash upon phloretin, quercitrin, maclurin, catechin, kino, etc. It crystallizes in rhombic prisms, containing 2Aq; is very sweet; and very soluble in water, alcohol, and ether. Pyrogallol Pyrogallic acid C 6 H 3 (OH) 3(1 2 3) is formed when gallic acid is heated to 200 . It crystallizes in white needles ; neutral in reaction; very soluble in water; very bitter; fuses at 132; boils at 210; 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. PHENOL DYES. Aurin C 19 H 14 3 , and Rosolic acid C 20 H 18 3 are substances existing in the dye obtained by the action of oxalic acid upon phenol in presence of H 2 S0 4 , known as corallin, or pceonin, which communicates to silk or wool a fine yellow-red color. Aurin crystallizes in fine, red needles from its solution in HC1. It is in- soluble in H 2 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, CH 4 (CO) 2 O, 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 attach them to two phenol groups by exchange with an atom of hydrogen. Thus phenol-phthalei'n, the simplest of the group, has the constitution, C.H 4 (\ ~n fl TT 4 !r T!' Phenol-phthalein is a yellow, crystal powder, insoluble \ \j\J V^ 8 H 4 ( L/H ) . 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-phthalei'n very valuable as an indicator of reaction. Resorcinol-phthalem Fluoresceme C 20 H 12 O 8 bears the same relation to resorcinol that phenol-phthalei'n does to phenol, and is obtained from resorcinol by a corresponding method. It is a dark-brown crystalline powder, whicli dissolves in ammonia to form a red solution, exhibiting a most brilliant green fluorescence. A tetra-bromo-derivative of fluorescme is used as a dye under the name eosin. QUINONES. The quinones are benzene derivatives in which two atoms of hydrogen are replaced by two oxygen atoms. The attachment of the -0.0- group is either ortho- or para-, never meta-. Ortho- quinones of the polybenzenic series, such as ft naphthoquinone and anthroquinone, are well-known compounds, but the mono-benzenic ortho-quinones are only known in their derivatives. HC CH C AROMATIC ALCOHOLS 351 The monobenzenic para-quinones may be considered either as peroxides, the bonds of the benzene ring remaining intact (Formula O I), or they may be considered as ring-ketones (Formula II), in which the two CO groups form a HC CH part of an oxidized hydroaromatic ring. The former view is favored ***' i A-I t> ,1 .-i \/ by the facts that the quinones are strong oxidizing agents, as are the [J peroxides in general, and that they (I). (II.) yield monosubstituted derivatives by replacement of their oxygen by univalents, as benzoquinone forms //-^TT % /"iT"r\ p-dioxybenzene, (HO)C^ CH ' CH ^C(OH) on reduction, and p- dichlorobenzene, C1C ^ CH ' CH ^CC1, by the action of PC1 5 . On the other hand, the existence of the C0=group in the quinones is indi- cated by the fact that they readily form oximes with hydroxylamine, a reaction characteristic of compounds containing C0=, as benzo- /CTT PTTX quinone forms quinone dioxime, HO.NC \CH CH/C'N.OH; an ^ if by reason of its oxidation of phenylhydrazine, benzoquinone forms no phenylhydrazone such compounds are formed by the naphtho- quinones. /O Quinone Benzoquinone C 6 H 4 : | is formed by the action of oxidants upon a variety of p-benzene derivatives, but best by limited oxidation of quinic acid. It crystallizes in golden-yellow prisms, f. p. 116, sublimes at ordinary temperatures, sparingly soluble in cold water, readily soluble in hot water, alcohol and ether. It has a peculiar, pungent odor, stimulates the lachrymal secretion, and irritates the skin. Reducing agents convert it into quinol. AROMATIC ALCOHOLS. The alcohols corresponding to this series of hydrocarbons are isomeric with the phenols. They contain the characterizing group of the primary alcohols, CH 2 OH ; once if the alcohol be monoatomic, twice if diatomic, etc., and they yield on oxidation, first an aldehyde and then an acid. Thus: C 6 H 5 .CH 2 OH=benzylic alcohol; C 6 H 5 .- CHO=benzoic aldehyde; C 6 H 5 .COOH=benzoic acid. The monohydric aromatic alcohols are produced by reactions sim- ilar to those by which the corresponding aliphatic compounds are produced (p. 212) : (1) By reduction of the corresponding aldehydes: C 6 H 5 .CHO+H 2 =C 6 H 5 .CH 2 OH 352 TEXT-BOOK OF CHEMISTRY (2) By saponification of alkyl benzenes having a halogen atom in a lateral chain: C 6 H 5 .CH 2 C1+KOH=KC1+C 6 H 5 .CH 2 OH (3) By the action of nitrous acid on the primary amides having the amido group in a lateral chain: C H 5 .CH 2 .NH 2 +NH0 2 =:H 2 0+N 2 +C 6 H 5 .CH 2 OH (4) By reduction of the unsaturated alcohols such as cinnamic alcohol : C 6 H 5 .CH:CH.CH 2 OH+H 2 =C 6 H 5 .CH 2 .CH 2 .CH 2 OH (5) By the action of trioxymethylene upon phenyl magnesium halides : C 6 H 5 .Mg.Br+H.CHO=C 6 H 5 .CH 2 O.MgBr and C 6 H 5 CH 2 O.MgBr+H 2 0=C 6 H 5 CH 2 OH+HO.Mg.Br They are capable of yielding isomeric products of further sub- stitution, ortho, para, or meta. Benzylic Alcohol Benzoic Alcohol Benzyl Hydrate C 6 H 5 .- CILOH does not exist in nature, and is of interest chiefly as cor- responding to two important compounds, benzoic acid and benzoic aldehyde (oil of bitter almonds). It is obtained by the action of potassium hydroxide upon oil of bitter almonds, or by slowly adding sodium amalgam to a boiling solution of benzoic acid. It is a colorless liquid ; boils at 206.5 ; has an aromatic odor ; is insoluble in water, soluble in all proportions in alcohol, ether, and carbon bisulphide. By oxidation it yields, first, benzoic aldehyde, C 6 H 5 CHO ; and afterward, benzoic acid, C H 5 .COOH. By the same means it may be made to yield products similar to those obtained from the alcohols of the saturated hydrocarbons. Secondary and tertiary aromatic alcohols are also known, such as phenyl-methyl carbinol, C 6 H 5 .CHOH.CH 3 and phenyl-dimethyl carbinol, C fl H 6 .COH ( CH 3 ) 2 - The secondary alcohols yield ketones on oxidation (p. 354). Di- and tri-hydric alcohols, such as the xylylene glycols, C a H 4 ( CH 2 OH ) 2 , and mesitylene glycerol, C a H 3 . ( CH 2 OH ) 3 (1 ^ 6) , are also known, as well as alcohols with unsaturated lateral chains, such as cinnamic alcohols, C 6 H S .CH:- CH.CHjOH, which occurs as its cinnamic ester in storax. It oxidizes to cinnamic aldehyde and cinnamic acid. ALPHENOLS, OR OXYPHENYL ALCOHOLS. These substances are intermediate in function between the alcohols and the phenols, and contain both substituted groups OH and CH a OH. OTT Saligenin o-Oxybenzylic Alcohol C.HQg 2 is obtained from salicin in large, tabular crystals; quite soluble in alcohol, water, and ether. Oxidizing 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 353 ALDEHYDES. The aromatic aldehydes are the first products of oxidation of the aromatic alcohols. Monaldehydes containing one CHO group and dialdehydes containing two such groups are known. The monaldehydes are formed: (1) By oxidation of the alcohols; (2) By decomposition of the alcohol bichlorides by water: C 6 H 5 .CHC1 2 +H 2 0=C 6 H 5 .CHO+2HC1. (3) By oxidation of the alcohol monochlorides by lead nitrate: C 6 H 5 .CH 2 C1+0=C 6 H 5 .CHO+HC1 (4) By distilling a mixture of the Ca salt of the acid and calcium formate : (C 6 H 5 .COO) 2 Ca+ (H.COO) 2 Ca=2C 6 H 5 .CHO+2CaC0 3 (5) By prolonged boiling of phenyl magnesium halides with or- thoformic esters, and hydrolysis of the product: C 6 H 5 .MgBr.+CH;(O.C 2 H 5 ) 3 =C 6 H 5 .CH:(O.C 2 H 5 ) 2 +C 2 H 5 O.Mg.Br. andC 6 H 5 .CH:(O.C 2 H 5 ) 2 +H 2 0=C 6 H 5 .CHO+2C 2 H 5 .OH (6) By the action of chromyl chloride, Cr0 2 Cl 2 , upon the hydro- carbons, and decomposition of the addition compound by water. Benzoic Aldehyde Benzoyl hydride C 6 H 5 .CHO is the main constituent of oil of bitter almonds, although it does not exist in the almond. It is formed, along with hydrocyanic acid and glucose, by the action of water upon amygdalin. It is also formed by the general methods given above ; by the dehydration of benzylic alcohol ; by the dry distillation of a mixture in molecular proportions of cal- cium benzoate and formate; 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 benzoyl cyanide. It is a colorless oil, having an acrid taste and the odor of bitter almonds; sp. gr. 1.050; boils at 179.4; soluble in 30 parts of water, and in all proportions in alcohol and ether. Oxidizing agents con- vert 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 2 S0 4 dissolves it when heated, forming a purple-red color, which turns black if more strongly heated. It forms a series of products of substitution, haloid, nitro, amido, etc. When perfectly pure, benzoic aldehyde exerts no deleterious action when taken internally ; owing, however, to the difficulty of com- pletely 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 354 TEXT-BOOK OF CHEMISTRY much as 10-15 per cent, of hydrocyanic acid, although said to be "purified." The presence of the poisonous substances may be de- tected by the tests given on page 304. Salicylic Aldehyde Salicyl hydride Salicylal Salicylous acid o-Oxybenzaldehyde C 6 H 4 (OH) (CHO) (2) exists in the flowers of Spircea ulmaria, and is the principal ingredient of the essential oil of that plant. It is best obtained by oxidizing salicin. It is a colorless oil ; turns red on exposure to air ; has an agree- able, aromatic odor, and a sharp, burning taste; sp. gr. 1.173 at 13.5; boils at 196.5; soluble in water, more so in alcohol and in ether. It is, as we should suspect from its origin, a substance of mixed function, possessing the characteristic properties of aldehyde and phenol, an oxymonaldehyde, or phenol aldehyde. Compounds of this class are formed by the action of chloroform upon the phenols in the presence of a caustic alkali, when the CHO enters the ortho- or para- position with reference to the phenolic hydroxyl. Thus phenol yields ortho- or para-salicylic aldehyde: C 6 H 5 OH+CHCl 3 +4KOH=3KCl+3H 2 0+C 6 H 4 .(OK)(i) (CHO) (2) (r(4) It produces a great number of derivatives, some of which are salts or esters, such as p-methoxybenzaldehyde, or anisic aldehyde, C 6 H 4 (CHO)(OCH 3 ) w , a product of oxidation of anethol. Vanillin Methylprotocatechuic Aldehyde m-Methoxy-p-oxybenzalde- hyde C 6 H 3 .CHO.(O.CH 3 ) (3 )(OH) (4) a methylated dioxybenzaldehyde, is the odoriferous principle of vanilla. It is produced artificially by oxidation of coniferin, C 16 H 22 8 , a glucoside occurring in coniferous plants. It crystallizes in needles, fuses at 80, is sparingly soluble in water, readily soluble in alcohol or ether. It has a pungent taste and a persistent odor of vanilla. On ex- posure to air it becomes partly oxidized to vanillic acid, C 8 H 8 4 . KETONES. The aromatic ketones are produced by the oxidation of the sec- ondary aromatic alcohols : 2C 6 H 5 .CHOH.CH 3 +0 2 =2H 2 0+2C 6 H 5 .CO.CH 3 Or by the action of caustic potash upon the aromatic ft ketone- carboxylic acids: C 6 H 5 .CO.CH 2 .COOH+2KOH=C 6 H 5 .CO.CH 3 -j-H 2 0+K 2 C0 3 Monoketones, diketones and triketones, containing one, two and three lateral chains with CO groups, are known. The monoketones, also called phenones, consist of a closed chain hydrocarbon group united to an open chain one by the group (CO)". They may also be considered as benzene, into which fatty acid radicals have been sub- stituted for hydrogen. The phenones containing two aromatic nuclei, as benzophenone : C 6 H 5 .CO.C H 5 , belong to the diphenyl derivatives. AROMATIC CARBOXYLIC ACIDS 355 The phenones are acted upon by the alkyl magnesium halides in the same manner as are those of the aliphatic series (p. 226). Thus benzophenone and phenyl magnesium bromide produce triphenyl carbinol : (C 6 H 5 ) 2 :CO+C 6 H 5 .Mg.Br.= (C 6 H 5 ) 2 :C(C 6 H 5 ).OMg.Br, and (C 6 H 5 ) 2 :C(C 6 H 5 )O.MgBr+H 2 0=(C 6 H 5 ) 3 lCOH+HO.Mg.Br Phenyl-methyl Ketone Acetyl benzene Acetophenone Hyp- none C 6 H 5 .CO.CH 3 is obtained by distilling a mixture of calcium benzoate and acetate ; by the action of zinc-methyl upon benzoyl chloride ; or by the action of acetyl chloride or bromide upon benzene in the presence of aluminium chloride. It forms large crystalline plates, fusible at 20. It has been used as a hypnotic. Acetophenone Oxime C 6 H 5 .C:(N.OH).CH 3 is isomeric with acetanilide, C 6 H 5 NH(CO.CH 3 ), and is converted into that substance by the action of concentrated H 2 S0 4 . AROMATIC CARBOXYLIC ACIDS. All six of the hydrogen atoms of benzene are replaceable by carboxyl groups, with formation of monocarboxylic acids, dicarboxylic acids, etc. There are also three series, o-, m-, and p-, of the bi-, tri-, and tetracarboxylic acids, and of the monocarboxylic acids above the first. These acids may be obtained by oxidation of the cor- responding alcohols, or aldehydes, where these are known. Like the aliphatic acids, they may be considered as being derived from the hydrocarbons by substitution of hydroxyl and oxygen for hydrogen in a lateral chain. MONOCARBOXYLIC AROMATIC ACIDS BENZOIC SERIES. These acids are formed by many methods, among which the most important are : ( 1 ) By oxidation of the lateral chain in hydrocarbons homologous with benzene. Thus toluene yields benzoic acid: 2C 6 H 5 .CH 3 +30 2 =2C 6 H 5 .COOH+2H 2 (2) By oxidation of the corresponding alcohols and aldehydes. (3) By the action of sodium and carbon dioxide upon the mono- bromobenzenes : , C 6 H 5 Br+C0 2 +2Na=NaBr+C 6 H 5 .COONa (4) By decomposition of the aromatic acid nitriles by acids or alkalies : C 6 H 5 .CN+KOH+H 2 0=C 6 H 5 .COOK+NH 3 (5) By fusion of the aromatic sulphonic acids with sodium form- ate: C 6 H 5 .S0 3 Na+H.COONa=C 6 H 5 .COONa+NaHS0 3 356 TEXT-BOOK OF CHEMISTRY The acids of this scries form many derivatives. In some of these the carboxyl is modified, leaving either the radical benzoyl, C 6 H 5 .CO, as in benzamide, C 6 H 5 .CO.NH 2 , or the trivalent group benzenyl, C 6 H 5 .C, as in benzenyl-amidine, C 6 H 5 .C^^. In others the substi- tution occurs in the benzene ring, as in the oxy-, halogen-, and nitro-benzoic acids, etc., e. g. anthranilic or o-amido-benzoic acid C 6 H 4 .COOH (1) (NH 2 ) (2) . Benzoic Acid C 6 H 5 .COOH exists in benzoin, tolu balsam, cas- toreum, and in several resins. It is obtained by the general methods given above; also from benzoin, and from the urine of herbivorous animals. The urine contains hippuric acid, which, on decomposition, yields benzoic acid. Conversely, when benzoic acid is taken into the body in moderate doses it is eliminated as hippuric acid. Benzoic acid crystallizes in white, transparent plates; the solid acid is odorless, but its vapor has a peculiar odor and produces a tendency to sneeze; it is sparingly soluble in cold water, readily soluble in hot water, in alcohol and in ether; fuses at 120, boils at 250, and sublimes at temperatures below its boiling point. Ben- zoic acid is not attacked by HN0 3 . Heated with lime, it yields ben- zene and calcium carbonate: C 6 H 5 .COOH+CaH 2 2 =,C 6 H 6 +CaC0 3 +H 2 a reaction corresponding to the formation of methane from sodium acetate. The benzoates are all soluble, the least soluble being the ferric salt. Homologues of Benzoic Acid. These are of two kinds: (1) Those in which the carboxyl and hydrocarbon groups replace different hydrogen atoms, the alkyl-benzoic acids, as cumic acid, or p-isopropyl benzoic acid, C 6 H 4 . ( C 3 H T ) (i) ( COOH ) w . (2) Those in which the carboxyl is separated from the benzene ring by a hydrocarbon group, the phenyl fatty acids, as phenyl- acetic acid, C^Hj.CH^COOH. In the terms above the first of this series there are place isomeres according to the distance from the ring in which the carboxyl /POOTT is introduced. Thus a phenyl-propionic acid, CH B .CH \ng and $ phenyl- propionic acid, CeH 5 .CH 2 .CH 2 .COOH. POLYCARBOXYLIC AROMATIC ACIDS. The di-, tri-, tetra-, penta-, and hexa-carboxylic aromatic acids are derived from benzene by substitution of from two to six carboxyls for hydrogen atoms. Of the superior homologues there exist a number of isomeres, increasing with the number of carbon atoms, according as the carboxyls are attached to the benzene ring, as in the phthalic acids, or are contained in lateral chains, as in phenyl-malonic acid, C 6 H V CH ( COOH ) 2 , and varying further by differences in orientation either in the benzene or the lateral chains. Phthalic Acids C 8 H 4 ( COOH ) 2 Ortho-, meta-, and para-phthalic acids are produced by oxidation of the corresponding bisubstituted benzene derivatives, and serve by their formation to determine whether a given compound is o-, m-, or p-. PHENOL CARBOXYLIC ACIDS AND THEIR ESTERS 357 Phthalic Acid Benzene-o-dicarboxylic acid C a H 4 ( COOH ) 2 a, 2> is ob- tained : ( 1 ) industrially by oxidation of naphthalene or tetra-chloronaphthalene, for usa in the manufacture of the phthalei'n dyes ; ( 2 ) by oxidation of o-xylene, o-toluic acid, etc.; (3) by direct union of carbon monoxide with salicylic acid: C 6 H 4 .OH.COOH-f-CO=:C 6 H 4 ( COOH ) 2 or with resorcinol: C 6 H 4 ( OH ) 2 -f 2CO=C 6 H 4 ( COOH ) 2 Phthalic acid crystallizes in prisms, sparingly soluble in cold water, readily soluble in hot water, alcohol, and ether, fuses at 213. Heated with excess of Ca(OH) 2 , it is decomposed into benzene and CO 2 ; but when its Ca salt is heated to 350 with one molecule of Ca(OH) 2 only one CO 2 is expelled, leaving calcium benzoate. Nascent hydrogen converts it into hydrophthalic acids. It is the only phthalic acid which yields an anhydride. Isophthalic Acid Benzene-m-dicarboxylic acid C 6 H 4 ( COOH ) 2 a, s> is formed by oxidation of m-xylene, m-toluic acid, and other m-benzene bisubsti- tuted derivatives. It crystallizes in fine needles, sparingly soluble in water, soluble in alcohol, fuses and sublimes above 300. Terephthalic Acid Benzene-p-dicarboxylic acid C 6 H 4 ( COOH ) 2 is formed by oxidation of p-xylene, p-toluic acid, and other p-benzene bisubstituted derivatives. It is insoluble in water, alcohol, and ether, and sublimes without melting. PHENOL CARBOXYLIC ACIDS AND THEIR ESTERS. These compounds have both hydroxyl and carboxyl attached to the benzene ring. They have the functions of phenol and of acid. They are formed (1) by fusing the sulphobenzoic acids with alkalies: C 6 H 4 (COOH)S0 3 H+KOH=S0 3 HK+C 6 H 4 (COOH)(OH) also similarly from the haloid acids: C 6 H 5 .Br.COOH+KOH=C 6 H 4 .OH.COOH+KBr (2) By fusion of the homologues of phenol with caustic potash, the methyl of the hydrocarbon lateral chain is oxidized to carboxyl. (3) By oxidation of the phenol-aldehydes by fusion with caustic alkalies. (4) By saponification of their esters, produced by oxidizing the sulphuric or phosphoric esters of the homologues of phenol. (5) By heating the phenols with carbon tetrachloride and caustic potash : C 6 H 5 .OH+CC1 4 +4KOH=C 6 H 4 .OH.COOH+2H 2 0+4KC1 (6) By the action of carbon dioxide upon the sodium phenates: 2C 6 H 5 .O.Na+C0 2 =C 6 H 4 .O.Na.COONa+C 6 H 5 .OH Di-, tri-, and tetra-carboxylic oxyacids are known. But the best known of the oxyacids are monocarboxylic, and monoxy-, dioxy-, and trioxy-, corresponding to the phenols of like hydroxyl content. MONOXY-MONOCARBOXYLIC ACIDS. Oxybenzoic Acids C 6 H 4 .OH.COOH. Of the three isomeric acids the meta-, f. p. 200, and the para-, f. p. 210, acids are ob- 358 TEXT-BOOK OF CHEMISTRY tained by the action of KOH on the corresponding bromobenzoic acids. Salicylic Acid o-Oxybenzoic Acid f. p. 155 occurs free, accompanied by salicylic aldehyde, in Spiraea ulmaria and, as its methylic ester, in oil of wintergreen. It is also formed by decom- position of salicin, coumarin or indigo. It is produced synthetically by the above reactions and, industrially, by heating sodium phenate in a current of carbon dioxide. The reaction is not C 6 H 5 .ONa+C0 2 =C 6 H 4 .OH.COONa, but 2C 6 H 5 .ONa+C0 2 =C 6 H 5 .OH+C 6 H 4 .ONa.COONa Salicylic acid crystallizes in prisms or needles, sparingly soluble in cold water, readily soluble in hot water, alcohol and ether, sweet and acid in taste. When heated, it distils in part unchanged, while a part loses oxygen and yields salol and xanthone, C 13 H 10 2 ; or salol, carbon dioxide and water. With Cl and Br it forms products of sub- stitution. With fuming HN0 3 it forms a nitro-acid and finally, picric acid. With ferric chloride it gives a fine violet color. Nascent hydrogen causes rupture of the ring, with formation of pimelic acid as a final product. Salicylic acid and its salts and esters are used as antiseptics and as antirheumatics. Phenyl Salicylate Salol C 6 H 4 .OH.COO(C 6 H 5 ) is formed by heating salicylic acid to 220: 2C 6 H 4 .OH.COOH=C 6 H 4 .OH.COO ( C 6 H 5 ) +C0 2 +H 2 also by the action of POC1 3 on a mixture of salicylic acid and phenol. It is a white, crystalline powder, faintly aromatic in taste and odor, almost insoluble in water, soluble in alcohol, ether and benzene, fuses at 43. It is not decomposed by weak acids, but is saponified by alkalies to form salicylic acid and phenol; hence it passes unchanged through the stomach to be decomposed in the intestine : C 6 H 4 .OH.COO(C C H 5 )+H 2 0=C 6 H 4 .OH.COOH+C 6 H 5 .OH Acetol Salicylate Salacetol C 6 H 4 .OH.COO(CH 2 .CO.CH 3 )- the ester of the keto-alcohol, acetol, is formed by the action of mono- chloracetone on sodium salicylate. It crystallizes in plates, spar- ingly soluble in water, readily soluble in alcohol, fusible at 71. It is saponified by alkalies with formation of acetol and salicylic acid, and is hence substituted for salol as a medicine when the formation of phenol is undesirable. Like acetol and its other esters, it reduces Fehling's solution. DI- AND TRIOXYMONOCARBOXYLIC ACIDS. Dioxycarboxylic Acids. The six isomeres corresponding to the three diphenols are known, as well as numerous alkyl derivatives, such as vanillic, PHENOL CARBOXYLIC ACIDS AND THEIR ESTERS 359 isovanillic* and veratric acids, which are derived from protocatechuic acid. The relations of these acids are shown by the following formulae: PYROCATECHOL. OH O= 3.4-Dioxybenzoic. = Protocatechuic. /3= 2.3-Dioxybenzoic, 0(CH 8 ) COOH Vanilllc acid. RESORCINOL. OH a-Resorcylic, = 3. 5-Dioxy benzole, /3 Resorcylic, = 2.4-Dioxybenzoic. 7 Resorcylic, = 2.6-Dioxybenzoic. 0(CH 3 ) OH COOH Isovanillic acid. QUINOL. OH OH 2. 5-Dioxy benzoic, = Gentisinic, = Hydroquinone-carboxylic. COOH Veratric acid. Protocatechuic Acid 3.4-Dioxybenzoic Acid C 6 H 3 ( COOH ) a) ( OH ) 2 &*) exists in the fruit of the star-anise, and is produced from many resins by fusion with KOH. It is formed by fusion of dibromobenzoic acid, and other similar derivatives, with KOH. The superior homologues of dioxycarboxylic acids are either dioxytoluic acids, etc., such as orsellinic acid, or dioxy-phenyl fatty acids, such as homo- gentisinic acid: COOH CHo.COOH OH CH 2 .COOH HO CH 3 2.6-Dioxyparatoluic. = Orsellinic. 2.5-Dioxyphenyl-acetic. = Homogentisinic. OH 3.4-Dioxyphenyl-acetic. =Homoprotocatechuic. CH 2 CHOH.COOH 3.4-Dioxypbenyl-lactic. = Uroleucic (?) Homogentisinic acid, or glycosuric acid, exists in the urine in " alkap- tonuria," probably accompanied by homoprotocatechuic and uroleucic acids, as well as by the monoxy-monocarboxylic acids mentioned above. Trioxycarboxylic Acids. Three of the six possible acids are known, two derived from pyrogallol, one from phloroglucin. Gallic Acid C 6 H 2 (COOH)(i)(OH) 3 (3, 4, 5) exists in nature in certain leaves, seeds and fruits. It is best obtained from nut-galls, which contain its glucoside, gallo-tannic acid. It is formed when bromo-protocatechuic acid is fused with, 360 TEXT-BOOK OF CHEMISTRY caustic potash. It crystallizes in long, silky needles with lAq, odorless, acidu- lous in taste, sparingly soluble in cold water, very soluble in hot water and in alcohol. Its solutions are acid. When heated to 210-215 it yields CO 2 and pyro-gallol. Its solutions reduce the salts of silver and of gold; they do not precipitate gelatin nor the salts of the alkaloids, as does tannin; and they give a blue-black precipitate with FeCl 3 . Tannins Tannic Acid are substances of vegetable origin, principally de- rived from leaves, barks and seeds. They are amorphous, soluble in water, astringent, capable of precipitating albumin, of forming imputrescible com- pounds with the gelatinoids (leather), and give green or blue colors with the ferric salts. Pure tannic acid has been obtained by removal of water from gallic acid: 2C 7 H 6 O 5 =C 14 H 10 O 9 -f-H s! O; it is, therefore, digallic acid. It exists in gall-nuts, excrescences produced upon oak trees by the punctures of certain insects (gallo- tannic acid ) . It is colorless, amorphous, odorless, very soluble in water, less so in alcohol, almost insoluble in ether. It forms a dark-blue liquid (ink) with solutions of ferric salts or, after exposure to air, with ferrous salts. Caffetannic Acid, C 30 H 1B O, 6 , exists in saline combination in coffee and Paraguay tea. It colors the ferric salts green, precipitates the salts of quinine and cinchonine, but not tartar emetic or gelatin, as tannic acid does. It yields caffeic acid, or 3-4 dioxycinnamic acid, C 9 H 8 O 4 , on decomposition. Cachou- tannic acid obtained from catechu, is soluble in water, alcohol and ether. It pre- cipitates gelatin, but not tartar emetic, and colors ferric salts grayish-green. Morintannic acid, or maclurine, C 13 Hi O 6 , is a yellow, crystalline substance, ob- tained from fustic. It is more soluble in alcohol than in water. Its solutions precipitate greenish-black with ferric salts, yellow with lead acetate, brown with tartar emetic and yellowish-brown with cupric sulphate. Quercitannic acid, C ltt Hi 6 O, , is the tannin of oak bark. It is a red powder, sparingly soluble in water, which forms a violet-red precipitate with ferric salts. Quinotannic acid exists in cinchona barks, in combination with the alkaloids. It is light yellow, soluble in water, alcohol and ether, astringent, but not bitter in taste. It is colored green by ferric salts. Dilute H 2 S0 4 decomposes it with formation of quina red, an amorphous substance, which yields protocatechuic and acetic acids on further decomposition. PHENYLIC ETHERS GLUCOSIDES. The oxides of the aromatic series, corresponding to the aliphatic ethers, and containing two cyclic hydrocarbon groups united by an oxygen atom, properly belong among the dibenzenic compounds but are more conveniently considered here. Phenyl Ether Diphenyl Oxide (C a H 5 ) 2 O is formed by heating phenol with aluminium chloride, or with zinc chloride: 2C 8 H 8 .OH=C 6 H 5 .O.C 6 H 5 +H J f and by other more circuitous methods. It crystallizes in long needles, having the odor of geranium, soluble in alcohol and in ether. Corresponding to it are a number of derivatives, formed by substitution of various univalents for the remaining phenol hydrogen. The mixed oxides, containing a phenyl and an alkyl group, are the phenyl ethers or phenol esters, derived from phenol. They are formed by heating metallic phenates with alkyl halides: C fl H 5 .O.K+CH 8 I=C 6 H 5 .O.CH,-fKI as the aliphatic ethers are produced from metallic alcoholates and alkyl halides. Methyl-phenyl Ether Anisol C 6 H 5 .O.CH 8 is a colorless, thin liquid, GLUCOSIDES 361 boils at 152 without decomposition. Sulphuric acid dissolves it, with forma- tion of irfethyl-phenol sulphonic acid. Ethyl-phenyl Ether Phenetol C 6 H 5 .O.C 2 H 5 is a colorless liquid, having an aromatic odor. It boils at 172. GLUCOSIDES. The name "glucoside" was first applied to certain natural prod- ucts, some of which are the active constituents of medicinal plants, which, on decomposition by dilute mineral acids, yield glucose and some other substance. Subsequently, it was found that the sugars derived from some of these substance", differ from glucose; some are pentoses, others hexoses; some monosaccharides, others disaccharides ; some aldoses, others ketoses. On the other hand, the second product of decomposition has been of the most varied character, phenols, alphenols, alcohols, oxyphenols, monobenzenic or dibenzenic, but, in all those natural glucosides which have been investigated, always a cyclic compound, containing a phenolic or an alcoholic group. The glucosides have usually been regarded as esters of glucose, etc., since the alcoholic character of the sugars has been recognized, but, as the union of the sugar and benzenic components is through an oxygen atom, and not by replacement of the hydrogen of a carboxyl, they are more properly regarded as ethers, formed by union of an aldose or ketose remainder with one of a phenolic or alcoholic benzenic compound, with elimination of H 2 0. The constitution of the gluco- sides cannot, however, be considered as established, as no natural glucoside has been obtained synthetically, although the products of decomposition of some are comparatively simple compounds. It is to be supposed that the union takes place through the aldehyde group, as the glucosides do not reduce Fehling's solution and do not form osazones. They probably contain some such grouping as: /ON CH 2 OH.(CHOH) 3 .CH CH.O.B, in which B represents the ben- zenic component. The glucosides are decomposed (hydrolyzed) by heating with dilute acids, or, at very slightly elevated temperatures, by certain enzymes, such as emulsin, which exists in almonds, myrosin, in mus- tard seeds, the invertin of malt, and salivary and intestinal enzymes. They are very slowly hydrolyzed by heating with water under, pres- sure, if at all ; and only a few of them are decomposed by alkalies. The glucosides yielding pentoses on hydrolysis are more properly designated pentosides. Phenyl Glucosides Glucosyl phenate CgH^Os.O.CeHg is the simplest of the glucosides, and is an artificial product, formed by mixing alcoholic solutions of acetochlorhydrose and potassium phenate : CHO. ( CH.C0 2 .CH 3 ) 4 .CH 2 C1+C 6 H 5 .O.K+4H 2 0=CHO. ( CHOH) 4 .- CH 2 .O.C 6 H 5 +KC1+4CH 3 .COOH 362 TEXT-BOOK OF CHEMISTRY It forms soluble, crystalline needles, fusible at 172, and is de- composed by emulsin into glucose and phenol. Among the more important of the natural glucosides are the fol- lowing: JEsculin Ci 5 H 18 B which exists in the rinds of horse-chestnuts. It forms colorless crystals, sparingly soluble in water, the solutions having a brilliant blue fluorescence, even when very dilute. It forms a yellow solution with HNO 3 , which becomes deep blood-red on supersaturation with ammonia. It is decomposed by dilute mineral acids, or by emulsin, into glucose and aesculetin, /CH:CH CoH.Oi, which is probably a dioxy-derivative of coumarin: C 6 H 2 (OH) 2 \0 CO Amygdalin C 20 'H. 27 N0 11 exists in the bitter almond, in the ker- nels of peach- and plum-pits, apple- and pear-seeds, and a great variety of other plants. It crystallizes in colorless prisms with 3 Aq, easily soluble in water, insoluble in ether, odorless, and bitter. It is decomposed by dilute mineral acids, or by emulsin, into two mole- cules of glucose and one each of benzoic aldehyde and hydrocyanic acid: C 20 H 27 N0 11 +2H 2 0=2C 6 H 7 0(OH) 5 +C 6 H 5 .CHO+CNH By the action of alkalies, particularly by heating with Ba(OH) 2 , amygdalin yields amygdalic acid, C 20 H 28 13 , of which amygdalin ap- pears to be the nitrile: C 6 H 7 0(OH) 4 .O.C 6 H 7 0(OH) 3 .O.CH(C X 6 H 5 )CN and this, on splitting off of the sugar, first forms the nitrile of man- delic acid: C 6 H 5 .CHOH.CN, the subsequent decomposition of which into C 6 H 5 .CHO and HCN is evident. Amygdalin itself is non-poi- sonous, but its ready decomposition, with formation of the extremely poisonous hydrocyanic acid, is a prolific source of cyanic poisoning. Coniferin C, fl H 22 O 8 is a glucoside occurring in the inner bark (cambium) of coniferous plants, and in asparagus and the sugar-beet. It crystallizes in silky, white needles, sparingly soluble in water, faintly bitter. With phenol and concentrated hydrochloric acid it assumes an intense blue color (pine-shaving reaction). It is decomposed by emulsin into glucose and coniferyl alcohol, which is a hydroxyl-oxymethyl cinnamyl alcohol: CH 3 J^Q^C 6 H 3 .CH:CH.CH 2 OH. By oxidation with chromic acid it forms glucovanillin, C a H n 5 .O.C 6 H 3 (OCH 3 )CHO, which is decomposed by emulsin into glucose and vanillin: methylprotocatechuic aldehyde. Glucovanillin, containing an aldehyde group, forms a crystalline com- pound with phenylhydrazine, and an oxime. By further oxidation it forms glucovanillic acid, and by reduction, the corresponding alcohol. Daphnin, C 18 H 18 O B , occurs in the bark of Daphne mezereum, and other species of Daphne. It crystallizes in colorless prisms, bitter and astringent, sparingly soluble in water and in ether, soluble in alcohol. It is colored bluish by ferric chloride. It is decomposed into glucose and daphnetin, C 9 H 8 O 4 , isonicric with aesculetin (above). Daphnetin has been shown to be a dioxycoumarin, having the hydroxyls in the positions 1, 2, by its synthesis by condensation of pyrogallol and malic acid: CH, ( OH ) 8 (i-iwj) +COOH.CH 2 .CHOH.COOH=H.COOH+2H 2 0+ /O(3> CO C,H 2 (OH) 2 (i2> \CH(*):CH GLUCOSIDES 363 Digitalis Glucosides. The active substance of digitalis consists, in part at least, of a glucoside, or glucosides, probably accompanied by products of decomposition, but the chemistry of these compounds requires further investigation. Digitonin, C 27 H 44 13 ( ?), is the most abundant constituent of the ' ' amorphous digitalins, ' ' and has little or no therapeutic value. It is an amorphous, white solid, very sol- uble in water, which crystallizes from its alcoholic solutions. It is decomposed by dilute hydrochloric acid into digitone'in, or digito- genin, C 15 H 24 4 , glucose and galactose. Digitalin, (C 5 H 8 2 )n( ?), separates in amorphous or nodular masses from its alcoholic solution. On decomposition it yields digitaliresin, C 16 H 22 2 , glucose and digi- talose, C 7 H 14 5 . It has the physiological action of digitalis upon the heart, and is the principal constituent of "Homolle's digitalin." Digitoxin, C 21 H 32 7 (?), crystallizes in fine needles, insoluble in water, soluble in hot alcohol and in chloroform. It is the most actively poisonous of the digitalis glucosides, and is the chief con- stituent of "Nativelle's digitalin." Digitalin gives a color-reaction which is not given by digitoxin : it forms a golden-yellow or brownish solution with concentrated H 2 S0 4 , which becomes violet-red by the action of bromine vapor. Toxicology. The prominent symptoms of poisoning by digitalis are: nausea, and occasionally vomiting; sometimes colic and diarrhea; after two or three hours, marked diminution in the frequency of the pulse, which may fall to 40 or even 25; dyspnea, attended by a sense of oppression in the chest and coldness of the extremities; headache, vertigo, and tendency to sleep; usually attacks of synocope occur, provoked sometimes by the slightest movement of the patient; death is generally by syncope, sometimes after several hours of coma succeeded by convulsions. The treatment: The patient must be kept strictly in the recumbent posi- tion. The stomach should be washed out with infusion of tea by the stomach tube. Stimulants should be given. Indican C 26 H 31 N0 17 is a glucoside occurring in the indigo plant. It is a yellow or light brown syrup, which cannot be dried without decomposition, bitter and disagreeable in taste, acid in re-, action, and soluble in water, alcohol and ether. It is very prone to decomposition. Even slight heating decomposes it into leucine, indicanin, C 20 H 23 N0 12 , and indiglucin, C 6 H 10 6 . A characteristic decomposition is that by which it yields indigo-blue and indiglucin, along with other products : 2C 20 H 31 N0 17 +4H 2 0=C 16 H 10 N 2 2 +6C 6 H 10 6 The substance found in the urine, and erroneously called "indi- can," is not a glucoside, but is potassium indoxyl sulphate: K.C 8 H 6 - N.S0 4 (see p. 417). Myronic Acid, C, Hi 9 NS 2 10 , exists in the seeds of black mustard as its K salt, which is hydrolyzed by myrosin into glucose, allyl isothiocyanate and KHS0 4 . 364 TEXT-BOOK OF CHEMISTRY Phloridzin, C 21 H ?4 O 10 , occurs in the root-bark of apple and other fruit trees. When ingested it causes glycosuria. It is hydrolyzed by boiling with dilute acids, or even with water, into a crystalline, dextrogyrous hexose, phlorose, and phloretin, C ]5 H 14 O 5 , which is further decomposed by hot alkalies into phloro- glucin and phloretic, or p-oxyhydratropic acid: CH 4 ( OH ) .C 2 H 4 .COOH. Salicin C 13 H 18 7 occurs in willow bark. It is a white, crys- talline substance, insoluble in ether, soluble in water and in alcohol, very bitter in taste. Concentrated H 2 S0 4 colors it intensely red, the color being discharged by addition of water. It is decomposed by emulsin, by saliva, or by mineral acids into glucose and saligenin. When taken into the economy it is converted into salicylic aldehyde and acid, which are eliminated in the urine. Populin, a glucoside from poplar bark, is benzoyl-salicin. Santonin C 15 H 18 3 is the active glucoside of the Artemisia pauci- flora. It is used as an anthelmintic. Solanin C 42 H 87 N0 15 ( ?) is a glucoside having basic properties, an alkaloid-glucoside, occurring in a variety of plants of the genus Solanum. It crystallizes in white, silky needles, acrid and bitter in taste, insoluble in water, sparingly soluble in alcohol and in ether. By the action of hot dilute acids it is decomposed into glucose and a basic substance, solanidin. ANHYDRIDES AND ACID HALIDES. The aromatic acidyls form oxides, or anhydrides, and haloid com- pounds, corresponding to those of the aliphatic acidyls, and produced by similar methods. Benzoic Anhydride (C 6 H 5 .CO) 2 is formed from benzoyl chlor- ide by several methods : as by a reaction between benzoyl chloride and silver benzoate: C 6 H 5 .CO.Cl+C 6 H 5 .COOAg=(C 6 H 5 .CO) 2 0+AgCl It is a crystalline solid, f. p. 42, b. p. 360. Phthalic Anhydride C 6 H 4 (CO) 2 :0 being formed from a dicar- boxylic acid, is produced from a single molecule of the acid, with elimination of H 2 0. It is formed by fusing phthalic acid. It sub- limes in needles; f. p. 128; sparingly soluble in cold water, soluble in hot water, with regeneration of the acid, very soluble in alcohol and in ether. It combines with phenols to form phthaleins. Salicylic Anhydride Salicylide C 6 H 4 /g^g\C 6 H 4 (probably) is formed by the action of phosphorus oxychloride on salicylic acid, It forms a crystalline compound with chloroform in which the latter behaves as water of crystallization : (C 7 H 4 2 ) 4 .2CHC1 3 , which is utilized to purify that anesthetic. Benzoyl Chloride C e H 5 .CO.Cl was the first obtained of the AROMATIC SULPHUR-DERIVATIVES SULPHONIC ACIDS 365 acidyl halides. It is formed by the action of hydrochloric acid upon benzoic acid, in presence of phosphorus pentoxide: C 6 H 5 .COOH+HC1=C 6 H 5 .CO.C1+H 2 Or by the action of chlorine upon benzoic aldehyde: C 6 H 5 .CHO+C1 2 =HC1+C 6 H 5 .CO.C1 Or, along with acetyl chloride, by the action of chlorine upon benzyl acetate: CH 3 .COO(CH 2 .C 6 H 5 )+2C1 2 =:C 6 H 5 .CO.C1+CH 3 .CO.C1+2HC1 The two chlorides are separated by fractional distillation. Benzoyl chloride is a colorless liquid; b. p. 198; having a pene- trating odor. With silver (or mercuric) cyanide it forms benzoyl cyanide : C 6 H 5 .CO.Cl+AgCN=C 6 H 5 .CO.CN+AgCl It acts readily upon the polyatomic alcohols and upon the hexoses, when shaken with their solutions in presence of caustic soda. With the hexoses pentabenzoyl compounds are formed, and crystallize out: CHO.C 5 H 6 (OH) 5 +5C 6 H 5 .CO.C1=CHO.C 5 H 6 (O.CO.C 6 H 5 ) 5 +5HC1 This is a reaction utilized for the isolation of hexoses and poly- atomic alcohols. A similar reaction, similarly utilized, occurs with the diamines, in which insoluble, crystalline, dibenzoyl compounds are formed : C 2 H 4 (NH 2 ) 2 +2C 6 H 5 .CO.C1=C 2 H 4 (NH.CO.C 6 H 5 ) 2 +2HC1 AROMATIC SULPHUR-DERIVATIVES SULPHONIC ACIDS. Many thio-aromatic compounds are known, as thiophenol, C 6 H 5 .- SH, phenyl sulphide, (C 6 H 5 ) 2 S, and thio-benzoic acid, C 6 H 5 .COSH. But the most important of the aromatic compounds containing sul- phur are the Sulphonic Acids (p. 286), monobasic acids containing the group S0 3 H, formed by the union of the aromatic hydrocarbon, or deriva- tive, with H 2 S0 4 with elimination of OH from the acid and H from the aromatic compound, a process called "sulphonation": C 6 H 6 +H 2 - S0 4 =C 6 H 5 .S0 3 H-|-H 2 0. The aromatic and polybenzenic sulphonic acids are formed much more readily than the corresponding aliphatic acids, and, being acid and soluble, are largely used as dyes. They are usually produced by the action of fuming H 2 S0 4 upon the aro- matic compound, with or without the aid of heat. The sulphonic acids are not decomposed by boiling with alkaline solutions, but their salts, when fused with caustic alkalies, yield phenols : C 6 H 5 .S0 3 K+KOH=C 6 H 5 .OH+K 2 S0 3 Distilled with potassium cyanide they yield nitriles : C 6 H 5 .S0 3 K+KCN=C 6 H 5 .CN+K 2 S0 3 366 TEXT-BOOK OF CHEMISTRY By the action of PC1 5 they are converted into their chlorides, e.g., C 6 H 5 .S0 2 C1, which may be, in turn, converted into sulphinic acids, sulphones, etc. They are easily soluble in water, and may be separated from their solutions, as sodium salts, by the addition of NaCl. Benzene-monosulphonic Acid C 6 H 5 .S0 3 H is formed by dis- solving benzene in weak fuming sulphuric acid at a slightly elevated temperature, and diluting with H 2 0. It crystallizes in extremely soluble, deliquescent plates with l l / 2 Aq. By the action of PC1 5 upon benzene monosulphonates, benzene sulphochloride is produced: C 6 H 5 .S0 3 K+PC1 5 =C 6 H 5 .S0 2 C1+KC1+POC1 3 This is an oily liquid, b. p. 246, which is a valuable reagent for amines and amido compounds. Three benzene-disulphonic acids C 6 H 4 (S0 3 H) 2 ortho-, meta- and para-, are known, also one benzene-trisulphonic acid C 6 H 3 (S0 3 H) 3 . Three toluene-sulphonic acids C 6 H 4 (CH 3 ).S0 3 H ortho-, meta- and para-, have been obtained. By the action of a mixture of ordi- nary and fuming sulphuric acids upon toluene at a temperature not exceeding 100, a mixture of the ortho- and para- acids is produced. When this is treated with PC1 5 , it is converted into a mixture of para- and ortho-toluene sulphonic chlorides C 6 H 4 .CH 3 .S0 2 C1. The ortho-chloride, when acted on by dry ammonia and ammonium car- bonate, is converted into ortho-toluene sulphamide CJEI^CHg.- S0 2 NH 2 . This product, when oxidized by potassium permanganate, is converted into benzoyl-sulphonic imide C fi H 4 .CO.S0 2 NH benzosulphinidium, or benzosulphinide or saccharin of the U. S. P. an odorless, crystalline powder, having great sweetening power, its sweet taste being still detectable in a dilution of 1-50,000. Spar- ingly soluble in water and in ether, readily in alcohol. Its solutions are acid in reaction. When heated with Na 2 C0 3 it is carbonized and gives off the odor of benzene. It is not attacked by H 2 S0 4 . Another series of sulphonic derivatives is obtained from the phenols. Among them is: Ortho-phenol sulphonic Acid Sozolic acid Aseptol C 6 H 4 - (OH) (1) (S0 3 H) (2) which is prepared by the action of cold concen- trated H 2 S0 4 upon phenol. It is a reddish, syrupy liquid, soluble in H 2 in all proportions, has a faint and not disagreeable odor. It prevents fermentation and putrefaction, and is a non-poisonous, non- irritant antiseptic. The salts of this and the corresponding para- and meta-acids have been used as antiseptics and insecticides, under the name of sulphocarbolates or phenol-sulphonates, e. g. Sodii phenolsulphonas (U. S. P.). Phenylsulphuric Acid Monophenyl Sulphate CO ^Q/ S0 2 iso- meric with the phenol monosulphonic acids, and corresponding to NITROGEN- CONTAINING DERIVATIVES OF BENZENE 367 the acid ethyl sulphuric ester, ethylsulphuric acid, is the acid phenyl sulphuric ester which exists in its salts in the urine, and is the type of numerous similar compounds, the " ester sulphates," which are formed in the economy from substances containing a phenolic hy- droxyl. The potassium salt of the acid is obtained by the action of potassium pyrosulphate upon potassium phenate: S 2 7 K 2 +C 6 H 5 .OK=C 6 H 5 .O.S0 3 K+S0 4 K 2 The free acid decomposes rapidly. NITROGEN-CONTAINING DERIVATIVES OF BENZENE. The nitrogen derivatives of benzene are very numerous, of great variety of structure, and include among their number several sub- stances of great industrial value. They may be classified into five principal groups: (1) The nitro- compounds, derived from other benzenic compounds by substitution of N0 2 for H, and the nitroso-compounds, containing the nitroso group, NO; (2) the hydroxylamine compounds, containing the group N \H H ' an( * the * r n i troso derivatives; (3) the amido- and imido-compounds, containing NH 2 and NH, the aromatic amines, amides, and amido-acids, and their derivatives; (4) the azo- and diazo-compounds and their numerous derivatives, containing the grouping N=N ; (5) the hydrazines, containing the grouping =N N=, and their nitroso derivatives. NITRO- AND NITROSO-COMPOUNDS Nitro-benzenes. These contain the nitro group directly attached to the carbon of the benzene ring. They are produced by the action of fuming HN0 3 , or a mixture of HN0 3 and H 2 S0 4 , upon the hydro- carbons : C 6 H 6 +HN0 3 =C 6 H 5 .N0 2 +H 2 They are yellow liquids, sparingly soluble in water. Their most important property is their ready reduction, first to hydroxylamine compounds : C 6 H 5 .N0 2 +2H 2 =C 6 H 5 .NH.OH+H 2 and then to amicto-compounds : C 6 H 5 .NH.OH+H 2 =C 6 H 5 .NH 2 +H 2 Mono-nitro-benzene Nitro-benzol Nitro-benzene Essence of Mirbane C G H 5 .N0 2 is obtained by the moderated action of fuming HN0 3 , or of a mixture of HN0 3 and H 2 S0 4 on benzene. It is a yellow, sweet liquid, with an odor of bitter almonds; sp. gr. 1.209 at 15; boils at 213; almost insoluble in water; very soluble in alcohol and in ether. Concentrated H 2 S0 4 dissolves, and, when boiling, decomposes it. Boiled with fuming HN0 3 it is con- 368 TEXT-BOOK OF CHEMISTRY verted into dinitro-benzenes. It is converted into aniline by re- ducing agents. It has been used in perfumery as artificial essence of bitter al- monds; but as inhalation of its vapor, even largely diluted with air, causes headache, drowsiness, difficulty of respiration, cardiac irregu- larity, loss of muscular power, convulsions, and coma, its use for that purpose is to be condemned. Taken internally, it is an active poison. Nitro-benzene may be distinguished from oil of bitter almonds (benzoic aldehyde) by H 2 S0 4 , which does not color the former; and by the action of acetic acid and iron filings, which convert nitro- benzene into aniline, whose presence is detected by the reactions for that substance (p. 371). Dinitrobenzenes. The three dinitrobenzenes are produced by boiling the mono-nitro compound with fuming HN0 3 . The meta- compound predominates, and may be separated by fractional crystal- lization from alcohol. It crystallizes in plates, fusible at 90, and is used in the preparation of certain dyes, and of explosives, such as roburite, sicherheit, etc. The gases resulting from such explo- sives are poisonous. Nitrotoluenes. C 6 H 4 .CH 3 .N0 2 The o- and p-compounds are pro- duced together by nitration of toluene, and exist in the commercial nitro-benzene. They may be separated by fractional distillation, the o-compound boiling at 218, and the p- at 230. By reduction they yield the corresponding toluidines, largely used in the color industry. By the action of HN0 3 on nitrobenzene, meta-compounds are ob- tained principally : NO, NO, + HNO, = +H,0 NO 2 And by action of HN0 3 on toluene, we obtain a mixture of ortho- and para-nitrotoluene : -f2HNO, = NO, +2H,0 When the first substituted group contains a double or triple link- age as in N0 2 , COOH, CHO, COCH 3 , CN, a second introduced group NITROGEN-CONTAINING DERIVATIVES OF BENZENE 369 occupies the meta-position preferably. But when the first substi- tuted group contains only single linkages as in Cl, Br, I, CH 3 , NH 2 , OH, mixtures of ortho- and para- groups are formed. Thus by the action of Cl on benzoic acid the meta-compound alone is formed: COOH COOH + C1 2 = +HC1 If ortho- or para-compound is desired, circuitous methods must be followed. Thus, for ortho acid, starting from phenol: OH -f CC1 4 + 4KOH = COOH COOH +4KC1+2H.O, and COOH +POC1.+HC1 Nitro-phenols Mononitro-phenols C 6 H 4 (N0 2 ) OH (12) , (13) and (14) are formed by the action of HN0 3 on C 6 H 5 .OH. The ortho compound (1 2) crystallizes in large yellow needles, spar- ingly soluble, and capable of distillation with steam. The meta and para compounds are both colorless, non-volatile, crystalline bodies. Methyl chloride converts nitrophenols into the corresponding nitro- anisols, C 6 H 4 .OCH 3 .N0 2 , and ethyl iodide into nitrophenetols, C 6 H 4 - OC 2 H 5 .N0 2 , which by reduction yield anisidines and phenetidines (p. 373). Two dinitro-phenols, (C 6 H 3 .OH(N0 2 ) 2(2 4), and C 6 H 3 .OH- (N0 2 ) 2 (2-6) are obtained by the action of strong nitric acid on phenol or on ortho- or para-mononitro phenol. They are both solid, crystal- line substances, converted by further nitration into picric acid. Trinitro-phenols C 6 H 2 (N0 2 ) 3 OH. Two are known; (1) Picric acid Carbazotic acid Trinitro-phenic acid (N0 2 ) in 2- It is formed by nitration of phenol, or of 1 2 4 or 1 2 6 dinitro- phenols, and also by the action of HN0 3 on indigo, silk, wool, resins, etc. It crystallizes in yellow plates or prisms, odorless, intensely bitter; acid in reaction; sparingly soluble in water, very soluble in 370 TEXT-BOOK OF CHEMISTRY alcohol, ether, and benzene; it fuses at 122.5, and may, if heated with caution, 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, crystal- line, and decomposed with explosion when heated. Picric acid colors silk and wool yellow. It is used as a reagent for the alkaloids, with many of which it forms crystalline precipitates, as it also does with many other substances. It is sometimes added to beer and to other food articles, to communicate to them either a bitter taste or a yellow color. Its solutions give yellow, crystalline precipitates with K salts ; green precipitates with ammoniacal CuS0 4 ; and an intense red color when warmed with alkaline KCN solution. It is poisonous, Nitro-cresols C 6 H 3 .CH 3 .OH.N0 2 The o- and p- compounds are known. They are readily converted into the corresponding dinitro compounds, C 6 H 2 .CH 3 .OH.(N0 2 ) 2 . The 2-6 dinitro compound is used as a dye in the form of its sodium salt, under the name Victoria orange, or saffron surrogate. It is poisonous. The nitroso-phenols are obtained by the action of nitrous acid upon the phenols; or by the action of hydroxylammonium chloride upon the quinones. p-Nitroso-phenol Quinoxime C 6 H 4 .(OH) (1) (NO) (4) , or C 6 - J I crystallizes in needles, and explodes when heated. Dinitroso- \N.OH resorcinol C 6 H 2 (OH) 2(13) (NO) 2(46) is a brown, explosive substance, used as a green dye, solid green. Nitro-acids, such as o-, m-, and p-nitro-benzoic acids, C 6 H 4 - COOH.N0 2 , etc., are known. They yield amido-acids by reduction. HYDROXYLAMINE COMPOUNDS. Compounds derived from hydroxylamine by substitution of phenyl or alkyl-phenyls for extra-hydroxyl hydrogen are formed as inter- mediate products of reduction of the nitro-benzenes (p. 367). Phenylhydroxylamine C 6 H 5 .N/ H is an intermediate product of reduction between nitro-benzene and amido-benzene : C 6 H 5 .N0 2 H-2H 2 =C 6 H 5 .N/OH + H 2 0, and C 6 H r N0 2 +3H 2 =C 6 H 5 .NH 2 +2H 2 It is readily oxidized to nitroso-benzene and other products, and it reduces Fehling's solution and ammoniacal AgN0 3 solution. Min- eral acids cause its intramolecular rearrangement to p-amido-phenol : C H 5 .N< H =C H 4 (OH) (1) (NH 2 ) (4) * /OH With nitrous acid it forms a nitroso derivative: C 6 H 5 .Nx^ () . It is a crystalline solid; f. p. 81; and forms a crystalline, colorless hydrochloride. NITROGEN-CONTAINING DERIVATIVES OF BENZENE 371 AMIDO-COMPOUNDS. The amido-benzenes are the counterparts of the aliphatic primary monamines. They are obtained by reduction of the corresponding nitro-compounds. The reaction is, with moderate reduction, not so simple as is expressed by the equation: C 6 H 5 .N0 2 +3H 2 =C 6 H 5 .NH 2 +2H 2 but several important intermediate products are formed (p. 367, and above). Aniline Amido-benzene Amido-benzol Phenylamine C 6 H 5 .- NH 2 exists in small quantity in coal-tar, and is one of the products of the destructive distillation of indigc. It is prepared by the re- duction of nitro-benzene by hydrogen: C 6 H 5 .(N0 2 )+3H 2 =C 6 H 5 (NH 2 )+2H 2 (see above) the hydrogen being liberated in the nascent state in contact with nitro-benzene by the action of iron filings on acetic acid. Pure aniline is a colorless liquid; has a peculiar, aromatic odor, and an acrid, burning taste; sp. gr. 1.02 at 16; boils at 184.8; crystallizes at 8; soluble in 31 parts of cold water, soluble in all proportions in alcohol, ether, carbon bisulphide, etc. When ex- posed to air it turns brown, the color of the commercial "aniline oil, ' ' and, finally, resinifies. It is neutral in reaction. Oxidizing agents convert it into rosaniline, C 20 H 19 N 3 , from which blue, violet, red, green, or black derivatives are obtained. Cl, Br, and I act upon it violently to produce products of substitution. Concentrated H 2 S0 4 converts it, according to the conditions, into sulphanilic, or p-amido- benzone sulphonic acid, C 6 H 4 (NH 2 ) (1) , (S0 3 H) (4) , or disulphanilic acid, or aniline 2-4 disulphonic acid, C 6 H 3 (NH 2 ) (1) ,(S0 3 H) 2(2 4) . With acids it unites, after the manner of ammonia, to form salts, most of which are crystallizable, soluble in water, and colorless, al- though by exposure to air, especially if moist, they turn red. The sulphate has been used medicinally. Potassium permanganate oxidizes it to nitro-benzene. Heated with H 2 S0 4 and glycerol it pro- duces quinoline, and substituted quinoline may be obtained by a similar reaction from substituted anilines. With alkyl magnesium iodides and bromides, aniline and methyl aniline produce the Meunier compounds : C 6 H 5 .NH.MgBr. and C 6 H 5 .- N(CH 3 ).MgBr. The former reacts with aldehydes to produce imines: K.CHO+C 6 H 5 .NH.MgBr=R.CH(O.MgBr).NH.C 6 H 5 and R.CH ( O.MgBr ) .NHC 6 H 5 =R.CH :N.C 6 H 5 +HO.MgBr. Aniline itself, when taken in the liquid form or by inhalation, is an active poison, producing symptoms similar to those caused by 372 TEXT-BOOK OP CHEMISTRY nitro-benzene (p. 368). Its salts, if pure, seem to have but slight deleterious action. Aniline may be recognized by the following reactions: (1) With a nitrate and H 2 S0 4 : a red color; (2) cold H 2 SO 4 does not color it alone; on addition of potassium dichromate, 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 mer- curic chloride: a deep crimson color; (6) in very dilute solution (1:250,000), aniline gives a rose color with chloride of lime, followed by ammonium sulphydrate. Toluidines CeH 4 (CH 3 ) (NH 2 ) Three toluidines, o-, m-, and p-, are known as the superior homologues of aniline. They occur in commercial aniline and play an important part in the production of aniline colors. Xylidines Amido-xylenes C 6 H 3 (CH 3 ) 2 (NH 2 ). Six compounds of this composition are known : two derived from ortho-xylene, three from meta-xylene, and one from para-xylene. Five of them exist in commercial xylidine. The toluidines and xylidines yield products of substitution and addition similar to those of aniline. Carbodiimidcs are substances having the general formula Cv^R, in which RR are two univalent radicals, usually belonging to the aromatic series. They are prepared from the sulphurei'des, by loss of the elements of carbon oxysul- phide, COS, by the action of heat or of oxidants. Anilides. These are compounds in which one of the H atoms of the amido group has been replaced by an acid radical. Or they may also be considered as amides, whose remaining hydrogen has been more or less replaced by phenyl, C 6 H 5 . Acetanilide Antifebrine Phenyl-acetamide C 6 H 5 (NH.CO.- CH 3 ) 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, and volatilizes unchanged at 295. It is sparingly soluble in cold water, soluble in hot water and in alcohol. When acetanilide is heated with an equal weight of ZnCl 2 , flav- aniline, a colored substance having a fine green fluorescence, and soluble in warm dilute HC1, is produced. Acetanilide and its derivatives in the urine respond to the indo- phenol reaction: Boiled a few minutes with HC1, a colorless solution is formed, which, on addition of H 2 and solution of phenol in chlorinated lime solution, assumes a turbid, dirty red color, and on addition of ammonia an indigo-blue color. By the further substitution of a group (CH 3 ) in acetanilide, methyl- acetanilide, or exalgine, C 6 H 5 .N(CH 3 ).C 2 H 3 0, is produced. It is formed by the action of methyl-iodide upon sodium acetanilide, C fl H5.NNa.C 2 H 3 0. It is a crystalline solid, sparingly soluble in H 2 0, readily in dilute alcohol. Its odor is faintly aromatic. NITROGEN-CONTAINING DERIVATIVES OF BENZENE 373 The "aniline dyes" now so extensively used, even those made from aniline, are not compounds of aniline, but are salts of bases formed, from it, themselves colorless, called rosaniline. Phenylamines Phenylenediamines, etc. Aniline is the simplest representative of a large class of substances. It may be considered as benzene in which H has been replaced by NH 2 , thus: C 6 H 5 .NH 2 . Its superior homologues, derivable from the superior homologues of benzene, each have at least three isomeres, ortho-, meta-, and para-, according to the orientation of the groups NH 2 and CnHan+i. Aniline may also be considered as ammonia in which H has been replaced by phenyl, C 6 H 5 , thus being a primary monamine Ce S 5 I N. The re- Jti 2 ) maining two H atoms may be replaced by other radicals to form an almost infinite variety of secondary and tertiary phenylamines, pre- cisely as in the case of the aliphatic monamines. Phenylcarbylamine Phenyl Isocyanide Isobenzonitrile C 6 H 5 .N : C is formed when chloroform is heated with aniline and caustic potash in alcoholic solution (p. 206). It is a liquid, having a most persistent, disagreeable odor. Nascent hydrogen converts it into methyl aniline. Heated to 220, it is con- verted into its isomere, benzonitrile, or cyanobenzene, C fl H 5 .CN, which is a liquid having an odor of bitter almonds; also formed by distilling potassium benzene sulphonate with potassium cyanide. XQTT Amido-phenols C 6 H 4 <'-^jj Three are known, ortho-, meta-, and para-, obtained by the action of reducing agents upon the corresponding nitro-com- pounds. Their methylic ethers, C 6 H 4 \N]5 are known as anisidines; and their ethylic ethers, C 6 H 4 \M[ 2 as phenetidines. By the action of glacial acetic acid upon paraphenetidine, an aceto-deriva- tive, para-acetophenetidine, C 6 H 4 (OC 2 H 5 ) (1) .(NH.C 2 H 3 O) W , is formed. It is used as an antipyretic, under the name phenacetine, and is a colorless, odor- less, tasteless powder, sparingly soluble in H 2 O, readily soluble in alcohol, fuses at 135. Its hot aqueous solution is colored violet, changing to ruby-red, by chlorine water. Aromatic acid amides are formed by methods similar to those by which the aliphatic amides are produced, and resemble them in their reactions (p. 312). Thus benzamide, or benzoyl amide, C 6 H 5 .CO.NH 2 , is formed by the action of benzoyl chloride upon ammonia: C 8 H V CO.C1+NH 3 =HC1+C 6 H 5 .CO.NH 2 as a crystalline solid, fusible at 130, or by the action of urea chloride upon benzene in presence of aluminium chloride: H 2 N.CO.Cl+C 6 H 6 =C 6 H 5 .CO.NH 2 -fHCl Two formulae of benzamide are possible: the amide formula, CH 5 .CO.NH 2 , and the imide formula, C 6 H 5 .COH:NH. Derivatives corresponding to each are known. Phthalamide C 6 H 4 /gNH 2 ' phthalamic acid, GA^eo^. and phthali- mide, C 6 H 4 /CO\ NH ape ^ ta i ne ^ f rom phthalic anhydride. The last named may be indirectly condensed, through its imide H, with the tatty acids to produce compounds which serve as starting points in syntheses of diamido fatty acids. The aromatic amido-acids greatly exceed the aliphatic (p. 321) in num- ber and variety. They are : ( 1 ) Amido-phenyl acids, which may be considered 374 TEXT-BOOK OF CHEMISTRY either as aromatic acids, in which a ring hydrogen atom (or atoms) has been replaced by NH 2 ; or as aliphatic acids, in which amido-phonyl (C a H 4 .NH,)' has replaced H in a hydrocarbon group; (2) phenyl-amido acids, considered either as aromatic acids, in which XH 2 replaces H in a hydrocarbon group of a lateral chain, or as amido-aliphatic acids, in which phcnyl (C' H 6 )' has been substituted for H in a hydrocarbon group; (3) anilido-acids aliphatic amido- acids in which phenyl has been substituted for H in NH 2 . In this class are included the anilides of the dicarboxylic acids (p. 371), e.g., oxanilic acid, ' (4) amic acids (p> 310)) derived from the dicarboxylic aromatic acids by substitution of NH 2 for OH in one carboxyl group. Besides these there are amido-acids referable to 1 and 3, in which the radical benzoyl, C a H 5 .CO, takes the place of phenyl, C 6 H 5 . The structure of these several acids is shown by the following formulae: CH 2 .COOH CH a .CH(NH 2 ).COOH NH.CH COOH NH a Amido-phenyl acetic acid. ^ Phenyl, a amido- propionic acid. CONH a (3) a Anilido- propionic acid. Those aromatic amido-acids in which the amido group is attached to the ring do not yield monochlor-acids by treatment with NOC1, but those in which the NH 2 is in a lateral chain do, as do also the amido-acids of the acetic and oxalic series (p. 323). Amido-phenyl Acids, of which anthranilic, or o-amido-benzoic acid, CH 4 (COOH) (1 (NH 2 ) (2) , is the type, are formed by reduction of the correspond- ing nitro-benzoic acids. Nitrous acid converts them into the corresponding oxyacids. Thus anthranilic acid yields salicylic acid. The o-acids exhibit a great tendency to the formation of lactams, some of which are indigo deriva- /CH 2 .CO(i) tives, as oxindole, the lactam of o-amido-phenyl acetic acid, C 8 H 4 and dioxindole, the lactam of o-amido-mandelic acid, C 6 H 4 /^_ Isatin, a product of oxidation of indigo, is the lactam of o-amido-benzoyl-formic /CO.CO (1) The amido-cinnamic acids are closely related to quino- K2) acid, C 6 H 4 v \ line. Phenyl-alanine, is a phenyl-amido acid: p phenyl- a-amido-propionic acid (formula above), which exists in certain lupines, and is a product of de- composition of the proteins. Its corresponding p-oxyphenyl derivative is: Tyrosine p-Oxyphenyl alanine ( HO ) (4) C,H 4 .CH 2 .CH ( NH 2 ) .COOH one of the earliest known products of protein decomposition. Tyrosine is formed from proteins, particularly from casein, by the action of proteolytic enzymes, and during putrefaction, and is also formed from them by boiling with HC1 or H 2 SO 4 , or by fusion with KOH, always accompanied by leucine. It exists normally in the intestine, and pathologically in the urine. It has been formed synthetically, from phenyl-acetaldehyde, C 6 H 6 .CH 2 .CHO, by conversion into phenyl-alanine, C 6 H 5 CH 2 .CH(NH 2 ) .COOH and p-amido-phenyl- a -alanine, CH 4 (NH 2 )( 4) CH 2 .CHNH 2 .COOH. It crystal li/es in silky needles, arranged in stellate bundles, very sparingly soluble in cold water, soluble in 150 parts of NITROGEN-CONTAINING DERIVATIVES OF BENZENE 375 hot water, *more soluble in the presence of acids or of alkalies, insoluble in alcohol and in ether. It unites with acids and bases to form salts. When heated it turns brown and gives off the odor of phenol; when heated to 270, it is decomposed into C0 2 and oxyphenylethyl-amine, C 6 H 4 (OH).CH 2 .CH 2 .NH 2 , which sublimes. With H 2 SO 4 , and slightly warmed, it dissolves with a transient red color; the solution, cooled, diluted, neutralized with BaC0 3 , and filtered, gives a violet color with FeCl 3 (Piria's reaction). When moistened with HNO 3 and slowly evaporated, it leaves a yellow residue, which forms a deep reddish-yellow color with NaOH (Scherer's reaction). Heated with water and a few drops of Millon's reagent it gives a red liquid, and forms a red precipitate (Hofmann's reaction). It gives the diazo reaction. p-Amidophenyl- a -alanine NH 2(4) C 6 H 4 .CH 2 .CH (NH 2 ) .COOH produced by reduction of p-nitrophenyl-alanine, is both a phenyl-amido and an amido-phenyl acid. Anilido Acids derived from the monocarboxylic acids are produced by the action of the monochlor-acids upon aniline, as the aliphatic amido-acids are obtained from ammonia. Thus monochloracetic acid and aniline yield anilido- acetic acid, or phenyl glycocoll, CH 2 C1.COOH+C 8 H 5 .NH 2 =C 6 H 5 .NH.CH 2 .- COOH+HC1. Hippuric Acid Benzoyl-amido-acetic acid Benzoyl glycocoll C 6 H 5 .CO.NH.CH 2 .COOH is similarly obtained from monochlor- acetic acid and benzamide : CH 2 C1.COOH+C 6 H 5 .CO.NH 2 =C 6 H 5 .CO.NH.CH 2 COOH+HC1 It is also formed by the action of benzoyl chloride upon glycocoll in the presence of sodium hydroxide: CH 2 (NH 2 ).COOH+C 6 H 5 .CO.C1=C 6 H 5 .CO.CH 2 .NH.COOH+HC1 Hippuric acid exists in the urine of the herbivora ; and in human urine in the daily quantity of 0.29-2.84 grams, and in larger amount when benzoic acid, cinnamic acid and other aromatic substances are taken. It crystallizes in prisms, colorless, odorless, bitter, sparingly soluble in water, readily soluble in alcohol, fuses at 187. When heated with acids or alkalies it is decomposed into benzoic acid and glycocoll. Oxidizing agents convert it into benzoic acid, benzamide and carbon dioxide. When heated alone it gives off a sublimate of benzoic acid and the odor of hydrocyanic acid. Its ferric salt is in- soluble, and is formed as a brown precipitate when FeCl 3 is added to its solution. Heated with lime it forms benzene and ammonia. Anilic Acids are anilido acids corresponding to the dicarboxylic acids. They may be considered as being formed by substitution of the univalent re- mainder of the acid for H in aniline, and therefore as anilides (p. 372) ; or by substitution of phenyl for H in the NH 2 group of the amic acids. Thus oxanilic acid, C 6 H 3 .NH.CO.COOH, corresponds to oxalic acid, COOH.COOH, and to oxamic acid, CONH 2 .COOH. /OTT Carbanilic Acid ^ : ^\>JHCH ^ e an ^ c ac ^ corresponding to carbonic and carbamic acids, and isomeric with phenyl urethane (p. 314), is not known in the free state. Its esters, however, are known as phenyl urethanes. A great number of phenyl-urea and phenyl-guanidine derivatives are also known. 376 TEXT-BOOK OF CHEMISTRY Related to the amido acids are the hydroxamic acids and the anil acids. Hydroxamic Acids are derivable from the imide formula of benzamide (p. 373) by substitution of OH for H in the imide group. Thus benzhydrox- amic acid, C 6 H 5 .C^, corresponds to benzamide, C.H 5 C.^**. Both H atoms in the OH groups are replaceable by alkyls to form esters. Amidoximes (p. 300) are derived from the hydroxamic acids by substitution of NH 2 for OH, e.g., benzenylamidoxime, CeH 5 .C \NH Anil Acids are aniline derivatives of the ketone-carboxylic acids, formed by the union of aniline and the acid, with elimination of water. Thus aniline and pyroracemic acid yield anil-pyroracemic acid: C 9 H 5 .NH 2 -j-CH,.CO.COOH=H 2 O-(-C 6 H 5 .N : C ( CH 3 ) .COOH DIAZO, DIAZOAMIDO, AND AZO COMPOUNDS. Diazo compounds contain the group N:N , united by one bond to an aromatic group, and by the other to an acid radical. Diazoamido compounds contain the group N:N.NH , united to two aromatic groups. Azo compounds contain the group N:N , united to two aro- matic hydrocarbon groups, or to one aromatic and one aliphatic hy- drocarbon group. Diazo Compounds are derivatives of diazobenzene, C 6 H 5 .N:NH, which is, however, only known in compounds in which the imide H has been replaced by acidyls or halogens, or of other cyclic compounds having the structure R.NrN.X, in which R is a cyclic hydrocarbon radical and X an acidyl or a halogen. These diazo compounds are very unstable, decomposing explosively on slight elevation of tem- perature or by shock. They are therefore rarely isolated in their own form of crystalline solids, but, on the other hand, their instability, or reactivity, renders their formation as intermediate products very serviceable in the formation of synthetic products, and in the manu- facture of the "azo dyes, " which include most of the so-called "ani- line colors." Their utility in this regard depends upon the facility with which the diazo group, .N:NX is displaced by other univalents, such as OH, H, CN, and halogens. The diazo compounds are produced by the action at low tempera- ture of HN0 2 upon the salts of the aromatic primary amines. Thus aniline chloride yields diazobenzene chloride: C 6 H 5 .NH 3 C1+HN0 2 =C 6 H 5 .N :NC1+2H 2 But if the temperature is allowed to rise the action proceeds further, with elimination of N and formation of a phenol : C 6 H 5 .N :NCl+H 2 0=C 6 H 5 .OH+N 2 -fHCl the sum of the reactions upon the amine being then the same as that of HN0 2 upon the aliphatic primary amines, i.e., the substitu- tion of OH for NH 2 , thus C H 5 .NH 2 +HN0 2 =C 6 H 5 .OH+N 2 +H 2 NITROGEN-CONTAINING DERIVATIVES OF BENZENE 377 This method of formation and decomposition of the diazo com- pounds is frequently utilized for the introduction of hydroxyl into aromatic molecules, starting either from the hydrocarbon or inter- mediate forms of nitro or amido derivatives. The process is referred to as diazotizing. A similar decomposition is effected by simply boiling aqueous solutions of diazo compounds : C 6 H 5 .N:N.HS0 4 +H 2 0=C 6 H 5 .OH+N 2 +H 2 S0 4 The replacement of the diazo group by H, with formation of the hydrocarbon, is effected by boiling with strong alcohol, which is oxidized to aldehyde: C 6 H 5 .N:N.HS0 4 +CH 3 .CH 2 OH=C 6 H 6 +N 2 +H 2 S0 4 +CH3.CHO The hydracids bring about the substitution of halogen for the diazo group, with formation of a monohalide: C 6 H 5 .N :N.HS0 4 +HI=C 6 H 5 I+N 2 + H 2 S0 4 A similar decomposition is effected by CuCl, and by PtCl 4 or PtBr 4 . Diazobenzene chloride in presence of CuS0 4 is converted by KCN into diazobenzene cyanide, which then splits off N to form cyanobenzene : C 6 H 5 .N :N.C1+KCN=C 6 H 8 .N :N.CN+KC1, and C 6 H 5 .N :N.CN=C 6 H 5 .CN+N 2 Notwithstanding the instability of the attachment of the diazo group, the diazo compounds also enter into reactions in which the N is not split off. Thus nascent hydrogen reduces the diazo salts to phenylhydrazine salts (p. 379) : C 6 H 5 .N:N.S0 3 K+H 2 =C 6 H 5 .HN.NH.S0 3 K With substances containing the grouping CH 2 .CO the diazo compounds react in alkaline solution to form hydrazones (p. 380), in which, however, the hydrazone group replaces H 2 , not 0. Thus with the malonic ester : C 6 H 5 .N :N.C1+H 2 C : ( COOC 2 H 5 ) 2 =C 6 H 5 .HN.N :C : ( COOC 2 H 5 ) 2 +HCl With the primary amines, whether aliphatic or aromatic, the diazo compounds form diazoamido- or disdiazoamido compounds (below). With the phenols the diazo salts do not produce azoxy compounds (p. 378), but first diazo oxy compounds: C 6 H 5 .N :N.HS0 4 +C 6 H 5 .OH=C 6 H 5 .N :N.O.C 6 H 5 +H 2 S0 4 , which suffer atomic transposition to form oxyazo compounds: C 6 H 5 .N:N.C G H 4 .OH, as do the diazoamido compounds (below). Diazoamido and Disdiazoamido Compounds. The diazoamido compounds, containing the group N:N.NH united to two aro- matic groups, are formed by the action upon each other of diazo salts and primary or secondary amines in equal molecular proportion. 378 TEXT-BOOK OF CHEMISTRY Thus diazoamido benzene, C H 5 .N :N.NH.C H 5 , is formed, as a yellow, crystalline, explosive solid, insoluble in water, soluble in hot alcohol, by the action of diazobenzene nitrate, or chloride, upon aniline: C 6 H 5 .N :NC1+NH 2 .C H 5 =C 6 H 5 .N :N.NH.C 6 H 5 +HC1 The most notable property of these substances is their transfor- mation, by intramolecular rearrangement into the isomeric p-azo- amido compounds. Thus diazoamido benzene becomes p-azo-amido benzene, C 6 H 5 N:NC 6 H 4 .(NH 2 ) (4) . This intramolecular transposition takes place slowly in the presence of traces of aniline salts, at the ordinary temperature. The disdiazoamido compounds, containing the group NrN.NH.- N:N , are formed under the same conditions as the diazoamido compounds, except that two molecules of the diazo salts are taken for one of the amine: 2C 6 H 5 .N :NC1+NH 2 .C G H 5 =C 6 H 5 .N :N.N(C C H 5 ) .N :N.C 6 H 5 +2HC1 Azo Compounds. The azo compounds contain the same group, N:N , as the diazo compounds, but they differ from the latter in that the two valences are both satisfied by hydrocarbon groups j either both aromatic, as in azobenzene, C 8 H 5 .N :N.C 6 H 5 , or one aromatic and one aliphatic, as in benzene azo-methane, C 6 H 5 .N:N.- CH 3 . They are ' ' mixed, "" symmetric, ' ' and ' * unsymmetric, ' ' accord- ing as they contain an aromatic and an aliphatic group, or two like aromatic groups, or two unlike aromatic groups. In designating the orientation of substituted groups the N:N attachments are con- sidered as occupying the (1) position in both hydrocarbon groups, and the positions of substitution in one ring are indicated by 2, 3, etc., and those in the other by 2', 3', etc. The azo compounds are formed: (1) By moderate reduction of nitro-aromatic compounds in alkaline solution. The reaction takes place in two stages, an azoxy compound being first formed and then further reduced. Thus nitro-benzene forms, first azoxybenzene, then azobenzene : .N0 2 2C 6 H 5 .N0 2 +3H 2 =C 6 H 5 .N^1N.C G H 5 +3H 2 0, and then N.C 6 H 5 +H 2 =C 6 H 5 .N :N.C 6 H 5 +H 2 The reduction readily progresses further, and always does so in acid solutions, with formation, first of a hydrazo product (p. 379), and finally an amido derivative (pp. 371, 373). Thus azobenzene forms, first, hydrazobenzene, or symmetrical diphenyl hydrazine, and then aniline : C 6 H 5 .N :N.C H 5 +H 2 =C H 5 .NH.NH.C 6 H 5 , and C 6 H 5 .NH.NH.C 6 H 5 +H 2 =2C H 5 .NH 2 (2) By reduction of the azoxy compounds. (3) The amido de- rivatives of the azo hydrocarbons are technically manufactured by NITROGEN-CONTAINING DERIVATIVES OF BENZENE 379 molecular* rearrangement of the diazoamido compounds (p. 378), or (4) by acting upon the tertiary anilines, or upon the m-diamines, with diazo salts. The azo compounds are much more stable than the diazo com- pounds. The hydrocarbons, such as azobenzene, C 6 H 5 .N:N.C 6 H 5 , are highly colored crystalline solids, which are not basic, and do not act as dyes. They are sparingly soluble in water, readily soluble in alcohol and in ether. Their most important derivatives are the amido-azo compounds, which are highly colored and strongly basic, crystalline solids, whose solutions have, however, no dyeing power. But they combine readily with salt-forming groups, notably to form sulphonic acids, which constitute many of the most extensively used "aniline dyes." p-Amido-azobenzene C 6 H 5 .N :N.(C 6 H 4 ) (NH 2 ) (4) prepared by the methods given above, is the starting point in the manufacture of several yellow, orange, and brown l ' diazo dyes, ' ' and of the * ' inuline dyes." It forms yellow needles, fusing at 123. HYDRAZINE COMPOUNDS. The aromatic hydrazines are derived from diamide, H 2 N.NH 2 , by substitution of hydrocarbon or other aromatic radicals for one or more of the hydrogen atoms. Hydrazo-benzene sym. Diphenyl-hydrazine C 6 H 5 .NH.NH.- C 6 H 5 is obtained by moderate reduction, as with zinc dust or sodium amalgam, of azobenzene: C a H 5 .N:N.C 6 H 5 +H 2 =C 6 H 5 .NHjra.C 6 H 5 It forms colorless crystals, having the oclor of camphor, fusible at 132, insoluble in water, soluble in alcohol and in ether. It readily oxidizes to azobenzene. Strong reducing agents break it up into two molecules of aniline. It is not basic; but, when treated with strong acids, it suffers molecular rearrangement, with formation of ben- zidine. or p (2r diamido-diphenyl, NH 2(4) .C 6 H 4 .C 6 H 4 .NH 2(4) . The unsymmetrical hydrazines resemble each other in their prop- erties and methods of formation, but differ from the symmetrical compounds, notably in that, containing the NH.NH 2 group, they are monacid bases, forming salts corresponding to those of ammonia. Phenylhydrazine C 6 H 5 .NH.NH 2 is formed by reduction of the diazo salts, of the diazo-amido compounds, or of the nitroso-amines. Thus stannous chloride and diazobenzene chloride yield phenylhydra- zine hydrochloride : C 6 H 5 N:NGl+2SnCl 2 +4HCl=C 6 H 5 .NH.NH 3 Cl+2SnCl 4 Zinc dust and acetic acid decompose diazoamido-benzene into phenylhydrazine and aniline : C 6 H 5 .N:N.NH.C 6 H 5 +2H 2 =C 6 H 5 .NH.NH 2 +NH 2 .C 6 H 5 380 TEXT-BOOK OF CHEMISTRY Phenylhydrazine is a yellow oil, which crystallizes at 23, and boils at 242 with partial decomposition, or at 120, without decom- position, under 12mm. pressure. It reduces Fehling's solution, or when boiled with CuS0 4 it liberates nitrogen and forms benzene. Sodium displaces the imide H to form a sodium phenylhydrazine : C 6 H 5 .NaN.NH 2 . The alkyl halides cause substitution of alkyls for both amide and imide H, forming a and ft phenylalkyl hydrazines. One of the latter, ft methyl-phenylhydrazine, C 6 H 5 .NH.NH.CH 3 , is an intermediate product in the formation of antipyrine from phenylhydrazine. Heated to 200 with fuming HC1, phenyl- hydrazine is converted into p-phenylene-diamine : C 6 H 5 .NH.NH 2 =: NH 2 .C 6 H 4 .NH 2 . Phenyl-hydrazones and Osazones. A most important action of phenylhydrazine is that with aldehydes and ketones, and with aldo- and keto-alcohols, and aldehyde and ketone acids and their esters, in which the bivalent remainder =N.NH.C 6 H 5 takes the place of oxygen in the aldehyde or ketone group, with the formation of phenyl-hydrazones and osazones, in much the same manner as the aldoximes and ketoximes are formed from the aldehydes and ketones. The formation of these derivatives is utilized to identify the alde- hydes and ketones and, notably, the aldoses and ketoses (p. 236, also "phenylhydrazine reaction"). The phenyl-hydrazones and osazones are formed by a variety of methods, usually by heating the aldehyde or ketone compound with phenylhydrazine hydrochloride in presence of sodium acetate. In the formation of the aldehydrazones and ketohydrazones the reaction takes place with elimination of water according to the equations: CH 3 .CH 2 .CHO+H 2 N.NH.C 6 H 5 r=CH 3 .CH 2 CH:N.NH.C 6 H 5 +H,0, and CH 3 .CO.CH 3 +H 2 N.NH.C 6 H 5 =:CH 3 .C :(N.NH.C 6 H 5 ).CH 3 +H 2 In the formation of the osazones of the aldoses and ketoses two molecules of phenylhydrazine react with one of the sugar, with elimi- nation of water. In the first stage of the reaction a hydrazone is formed as with the aldehydes and ketones. Thus with glucose and fructose respectively (pp. 240, 241) : CHO CH:N.NH.C fl H 6 (CHOH) 4 -fH 2 N.NH.C 4( H 5 = (CHOH) 4 -fH 2 O, and CH,OH CH,OH CH,OH CH 2 OH CO C:N.NH.C 6 H 5 ( CHOH ) ,+H 2 N.NH.C 6 H 1 , = ( CHOH ) , + H a O ; CH,OH CH Z OH HYDROCARBONS 381 The CHOH or CH 2 OH group vicinal to the first substitution then becomes oxidized to CO or CHO, and a second =N.NH.C 6 H 5 group is substituted for the to form the osazone : CH:N.NH.C 6 H 5 CH:N.NH.C 6 H 5 CO C:N.NH.C 8 H 5 (CHOH) 3 -fH 2 N.NH.C 9 H 5 = (CHOH), +H 2 0, and CH 2 OH CH 2 OH CHO CH:N.NH.C 6 H, C : N.NH.C 6 H 5 C : N.NH.C 9 H 6 ( AnOH ) 3 +H 2 N.NH.C a H 6 = ( feOH ) s +H 2 0, CH 2 OH CH 2 OH A comparison of the above formulae will indicate why it is that glucose and fructose yield one and the same osazone, called glucosa- zone. The phenyl-hydrazones are also utilized in the formation of con- densed heterocyclic compounds. Thus acetone phenyl hydrazone, CH 3 .C :N.NH.C 6 H 5 CH 3 .C.NH\ is converted into a methyl indole (p. 415), CH 3 CH / C 6 H 4 , by loss of NH 3 . Acid Derivatives of Phenylhydrazine. A great number of compounds are known, formed by the substitution of acid radicals for the amide or imide hydrogen of phenylhydrazine. These compounds bear the same relation to phenylhydrazine that the anilides bear to aniline, and some of them have been used as antipyretics, e. g., /3 acetophenyl-hydrazide Hydracetine C 6 H 8 .- NH.NH.CO.CH 3 formed as a white, crystalline, tasteless, and odorless powder, sparingly soluble in water, by the action of acetyl chloride or of acetic an- hydride upon phenylhydrazine. It is the active ingredient of an antipyretic called pyrodine. B. HYDROAROMATIC COMPOUNDS WITH A SINGLE NUCLEUS. The hydroaromatic compounds may be considered as derived from the benzenic by rupture of one or more of the double linkages of the benzene ring (p. 336), by which the valence of the nucleus is changed from six to eight, ten or twelve. HYDROCARBONS. Hexahydrobenzenes Cyclohexanes Naphthenes These compounds, of which hexahydrobenzene, H 2 C \cH 2 CH 2 2 / CHz ' is the sim P lest > and the P arent substance of the hydroaromatic compounds, exist in Russian petroleum, in coal tar, and in "rosin-oils." They are isomeric with the defines, from which they 382 TEXT-BOOK OF CHEMISTRY may be distinguished by the fact that they do not combine with bromine. With chlorine they form mono-chlor substitution products which behave like alkyl chlorides. Terpenes. Most of the volatile, or essential oils, or essences, obtained by distillation of various plants with steam, consist of hydrocarbons having the formula C 10 H ia , and most of the camphors and resins are alcoholic or ketonic derivatives of these hydrocarbons. A few of the essential oils, having the formula C 5 H 8 , are known as hemiterpenes, or define terpenes, and are un- saturated aliphatic compounds. Some of the aromatic terpenes also are poly- meres, having the formulae x ( C 5 H 8 ) . Although the constitution of the aromatic terpenes is not completely established, they are hydro-aromatic hydrocarbons of which the camphors are alcohols or ketones. Turpentine is a yellowish-white, semi-solid substance, having a balsamic odor, which exudes from incisions in the bark of Pinus palustris, P. tceda, and other Coniferce, and which may be taken as the type of a number of other similar products. These substances, when distilled with steam, yield two products, one a solid, yellow or brown residue, a stearoptene, such as rosin or colophany; the other a volatile, oily liquid, an eleoptene, such as oil, or essence, of turpentine. Oil of turpentine is insoluble in water, mixes with alcohol and with ether, and dissolves phosphorus, sulphur and caoutchouc. When exposed to the air it is oxidized to gummy, aldehydal products, which finally harden, hence its use as a drier in the manufacture of paints and var- nishes. On contact with HNO 3 , its oxidation is so violent as to cause ignition. Hydroterpenes are naphthenes (p. 381) obtained by decomposition of cer- tain natural alcohol-camphors. Thus hexahydrocymene, H 3 C.CH \CH 2 C:H 2 / CH.CH/', is derived from menthol (p. 383). \U1 3 HYDROAROMATIC ALCOHOLS. The hydroaromatic alcohols are, for the most part, "ring alcohols," and contain either CHOH or COH, as a part of the ring, although in some, as in some of the terpan alcohols, the alcoholic group, which may then also be CH 2 OH, is contained in the lateral chain. These alcohols may be obtained by reduction of the corresponding ketones, or of other aromatic or hydroaromatic compounds. They are produced by the action of organic magnesium compounds by reactions similar to those by which aliphatic alcohols are formed (p. 212). Magnesium cyclohexane chlorides are obtained by the action of magnesium upon cyclohexane chlorides: and these in turn react with aldehydes and ketones to produce crystalline compounds from which the alcohols are produced by hydrolysis. Thus cyclo- hexyl carbinol is produced from hexahydrobenzene and trioxymethylene : C 6 H n .Mg.Cl-fH.CHO=:C a H n .CH 2 O.Mg.Cl and C 6 H u .CH 2 O.Mg.Cl-fH 2 O=C 6 H n .CH 2 OH+HO.Mg.Cl. Several of them, such as quercite, inosite and some of the camphors, are natural products. Quercite H 2 C \CHOHiCHOH / CH H a pentatomic alcohol, obtained from acorns. It is a sugar-like substance, but is not affected by alkalies, does not ferment, and does not reduce Fehling's solution. F. p. 235; [a] D = -f24.16. Inosite C a H 6 ( OH ) fl CHOH \ CHOH CHOH/ CHOH metameric, though not rrlat-d, to the glucoses, is a hexatomic alcohol, which exists in three optical modifications. The inactive modification exists in the liquid of muscular tissue, HYDROAROMATIC KETONES AND ACIDS 383 in the lungs, kidneys, liver, spleen, brain and blood; in traces in normal urine, and increased in Bright's disease, in diabetes, and after the use of drastics in uremia ; in the contents of hydatid cysts ; in beans and peas, and in certain other seeds and leaves. It crystallizes in needles, usually arranged in cauli- flower-like masses, has a sweet taste, is readily soluble in water, sparingly soluble in alcohol, insoluble in absolute alcohol and in ether. It does not fer- ment, is not colored by alkalies, and does not reduce Fehling's solution. When heated to 170 with HI, it is decomposed into phenol, diiodophenol and benzene. When treated with HN0 3 evaporated to near dryness, the residue moistened with NH 4 OH and CaCl 2 , and again evaporated, a rose-red residue is left (Scherer's reaction). Mercuric nitrate produces in solutions of inosite a yellow precipitate, which, on cautious heating, turns red. The color disappears on cooling and reappears on heating (Gallois' reaction). Menthol Oxyhexahydrocymene H,C.CH GH.CH is a monacid menthan alcohol. It is the chief constituent of oil of peppermint. It crystallizes in prisms, fusible at 42, sparingly soluble in water, readily soluble in alcohol, ether and carbon bisulphide, and in acids. Corresponding to it are a series of menthyl esters. Terpins. There are two diacid menthan alcohols, in which the hydroxyls occupy the 1.8 positions. The formula of cis-terpin, the parent substance of H 3 C\ /CH 2 .CH 2 \ terpin hydrate and of cineol, is now considered as being C C- HO/ \CH 2 .CH 2 / /TT / OTT ( C=(CH ) > while in trans-terpin the positions of the CH 3 and OH attached to C ( 1 ) are reversed. Cis-terpin is obtained by dehydration of terpin hydrate, and also from [d-)-l]-limonene dihydrochloride. It is crystalline, fuses at 104, and boils at 258. It absorbs water eagerly to form terpin hydrate. Gaseous HC1, or PC1 3 , converts it into [d-fl]-limonene hydrochloride. Terpin Hydrate Ci H 18 ( OH ) 2 -|-H 2 O is formed when oil of turpentine re- mains long in contact with water, more rapidly in presence of alcohol and dilute HN0 3 ; also, similarly, from pinene and from limonene. It forms rhombic crystals, fusible tit 117, with loss of H 2 and conversion, slowly, into terpin. It is easily soluble in alcohol, sparingly soluble in water, chloro- form and ether. It is used as an expectorant. Cineol Eucalyptol C 10 H 16 (OH) 2 another diacid menthan alcohol is ob- tained from the leaves of Eucalyptus globulus, and also exists in wormseed oil (Oleum cince) and in other volatile oils. It is a colorless oil, having a camphor- like odor; sp. gr. 0.93 at 15; b. p. 176; n D == 1.4559; soluble in alcohol, sparingly soluble in water. Dry HC1 gas passed through its petroleum ether solution separates white scales of eucalypteol, C 10 H 16 .2HC1, which is decomposed by water with regeneration of cineol. Borneol Camphol Borneo Camphor C 10 H 18 a monacid alcohol, is the best known of the camphan alcohols. It exists in three optical modifica- tions; the d-borneol being the one usually met with, and obtained from Dryobalanops camphora. The d- and 1-modifications are both formed by hydro- genation of laurel camphor. It forms small, friable crystals; has an odor re- calling those of laurel camphor and of pepper, and a hot taste; is insoluble in water, readily soluble in alcohol, ether, and acetic acid; fuses at 203; boils at 212. It is oxidized to laurel camphor by HN0 3 . Heated with KHS0 4 , it is decomposed into camphene and H 2 0. HYDROAROMATIC KETONES AND ACIDS. The hydroaromatic ketones are " ring ketones," the CO group forming a part of the ring. They are formed: (1) by reduction of the corresponding 384 TEXT-BOOK OF CHEMISTRY aromatic phenols; (2) by oxidation of the secondary ring-alcohols: (3) by condensation of the esters of the aliphatic ketone acids, or of the ketones. d-Camphor Common camphor Laurel camphor Japan cam- phor C 10 H 16 is the most important of the hydroaromatic ketones. It is obtained from the camphor tree (Laurus camphora), and is formed artificially by oxidation of borneol or of camphene. It forms translucent, friable crystals; hot and bitter in taste, aromatic; spar- ingly soluble in water, quite soluble in acetic acid, methylic and ethylic alcohols, and the oils; f. p. 175; b. p. 204; sp. gr. 0.985; sublimes at all temperatures; [a] D = -(-44.22. It ignites readily, and burns with a luminous flame. Cold HN0 3 dissolves it, and H 2 precipitates it unchanged from the solution. Hot HN0 3 , or potassium permanganate, oxidizes it to d-camphoric acid. Distilled with P 2 5 it yields cymene, C 10 H 14 . Reducing agents convert it into borneol. Heated with iodine, it is converted into car- vacrol. Bromine unites with it to form ruby-red crystals of an un- stable compound, C 10 H 14 OBr 2 , which, when heated, fuse and give off HBr, leaving an amber-colored residue, which, on recrystallization from boiling alcohol, leaves long, hard, rectangular crystals of monobromo-camphor, C 10 H 15 OBr; f. -p. 76; soluble in alcohol and in ether. 1-Camphor is obtained from the oil of Matricaria postlanium; [a] D = 44.22. [d+1] -Camphor exists in the essential oils of rosemary, sage, lavender and origanum, or is formed by mixing d- and 1- camphors, or by oxidation of [d+1] -borneol, or of [d+1]- camphene. F. p. 179. Hydroaromatic Carboxylic Acids. A great number of these acids are known, some pure acids, others oxy- or ketonic acids, containing from one to six carboxyl groups, and hexahydro-, tetrahydro- and dihydro-. The most important are: Quinic Acid Hexahydro-tetraoxybenzoic Acid C 6 H 7 ( OH ) 4 COOH - which exists, combined with the alkaloids, in cinchona barks, also in coffee beans and in other plants. It forms hard, transparent prisms, soluble in water and in alcohol; fuses at 160; laevogyrous. On distillation, it yields phenol, hydro- quinol, benzoic acid and salicylic aldehyde. Hydriodic acid reduces it to benzoic acid. Terebic Acid C 7 H 10 4 f. p. 175; and Terpenylic Acid C 8 H 12 4 f. p. 90, are oxidation products of oil of turpentine, obtained, the former with HNOj, the latter with chromic acid mixture. Camphoric Acids C h H 14 ( COOH ) 2 The d-, 1-, and [d-f 11 -acids are known. d-Camphoric acid is produced by oxidizing common d-camphor by heating with HNO 8 . It forms colorless, odorless needles, soluble in alcohol, ether and boiling water; f. p. 187; [a] D =-f49.7. By further oxidation it yields camphoronic acid, or trimethyl-tricarballylic acid. Resins are generally the products of oxidation of the hydro- carbons allied to pinene; are amorphous (rarely crystalline) ; insol- COMPOUNDS WITH CONDENSED NUCLEI 385 uble 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, e.g., benzoin, liquidambar, Peru balsam, styrax, balsam tolu; (2) oleo-resins consist of a true resin mixed with an oil, e.g., Burgundy and Canada pitch, Mecca balsam, and the resins of capsicum, copaiba, cubebs, elemi, lupulin; (3) gum-resins, mixtures of true resins and gums, e.g., aloes, ammoniac, asafetida, eupJiorbium, galbanum, guaiac, myrrh, olibanum, scammony ; (4) true resins, hard substances con- taining neither essences, gums nor aromatic acids, e.g., resin, copal, dammar, jalap, lac, sandarac; (5) fossil resins, e.g., amber, asphalt, ozocerite. C. COMPOUNDS WITH CONDENSED NUCLEI. These compounds contain two or more benzene rings, or one or more benzene rings and a pentacarbocyclic ring, fused together in such manner that the adjacent rings have two carbon atoms in com- mon. The parent hydrocarbons of these compounds are: indene, fluorene, naphthalene, anthracene, phenanthrene, chrysene, and picene : H H H H H C C C C C //\ //\ X\\ f/\ X\\ HC C CH HC C C CH HC C CH H(i ^H H( l [1 {j H 5 ) 3 C.OH, and diphenyl-m-toluyl carbinol, BsJjtCfOHj.CaH^CHj^, are alcohols, whose triamido-derivatives are pararo- sanilin and rosanilin. They are formed by oxidation of the hydrocarbons. Triphenyl carbinol is the principal product of the action of CO 2 on phenyl mag- nesium bromide. In the first stage of the reaction: C 8 H 5 .MgBr+C0 2 =C 6 H 5 .COO.Mg.Br; then C 8 H 5 .COO.Mg.Br-f2C 6 H 5 .Mg.Br=(C < ^B 5 ) 3 =C.O.MgBr-(-MgO-fMgBr 1 and then ( CH 5 ) ,;CO.Mg.Br-f H,O= ( C.H 5 ) ,:COH-|-HO.Mg.Br These reactions are somewhat similar to those by which tertiary aliphatic alcohols are produced by acidyl halides and oxides (see No. 10, p. 213). They form nitro- and amido-derivatives of technical importance. HETEROCYCLIC COMPOUNDS. These compounds differ from the carbocyelic in that they contain elements other than carbon as constituents of the nuclei. They form series parallel to the carbocyelic, from which, indeed, they may be considered as being derived by substitution in the rings. Thus thiophene corresponds to pentole, pyridine to benzene, and quinoline to naphthalene: H H H C C C /\\ //\ /\\ HC CH HC C CH HC CH HC C CH \// \\/ \// C C C H H H Pentole. Benzene. Naphthalene. 390 TEXT-BOOK OF CHEMISTRY H H H C C C //\ /\\ /\\ HC C CH HC - CH HC CH II HC C CH HC CH HC CH \\/ \// \ / \// C N S N H Tbiophene. Pyridine. Quinoline. The elements which can be thus introduced into a cyclic nucleus are few; oxygen, sulphur, selenium, phosphorus and nitrogen being the only ones now known to enter into such formation, and of these the nitrogen-containing compounds are far the most numerous and the most important. The facility with which the N atom takes the place of the methine group, CH=, in the benzene ring is to be anticipated from their equivalence. Pyridine also resembles benzene in its general characters, and, on the other hand, the five membered compounds, furfurane, thiophene and pyrrole, have general charac- ters similar to those of benzene, from which they may be considered as being derived by substitution of the bivalents 0, S, and NH for one of the three acetylenes, CH:CH , of benzene. The number of hetero-atoms which may be contained in the nucleus is not limited to one, and five and six membered rings containing as many as four nitrogen atoms, the tetrazoles and tetrazines, are known. A classification of the heterocyclic compounds requires many subdivisions, because of the great number and variety of these sub- stances, due to the presence of one or more atoms of one or more of the elements above mentioned, in three, four, five or six mem- bered rings, contained in mono-, di-, tri-, or tetra-nucleate mole- cules, in which, also, differences in the ring-valence are caused by differences in internal linkage. A broad classification may, however, be here followed, somewhat similar to that for the aromatic sub- stances (p. 339). A. Mono-nucleate compounds : containing a single nucleus. These may be subdivided into :(a) Substances containing three-membered H 2 C\ H 2 C\ rings; such as ethylene oxide, I 0, sulphide, I S, and imide, H 2 C/ H 2 C/ H 2 C\ NH. (6) Four-membered compounds, such as trimethylene oxide, H 2 C-0 H 2 C-0 H 2 C-CH a I , thetin, | | , and trimethylene imide, H a C-CH 2 H 2 C-S HJC-NH HC=CH\ (c) Five-membered substances, such as furfurane, 0, HC=CH/ HC=CH\ HC=CH\ thiophene, S, and pyrrole, | NH. HC=CH/ HC=CH/ FIVE MEMBERED HETEROCYCLIC RINGS 391 HC-CH=CH (d) Six-membered compounds, such as pyridine, || HC CH=N H 2 C-CH a -CH a N=N CH piperidine, I | , and sym. tetrazine, I H 2 C-CH 2 -NH HC=N N The five- and six-membered compounds are much more numerous and important than the three- and four-membered. B. Condensed compounds, containing two or more rings, usually five- or six-membered, of which at least one is heterocyclic, fused together, and having two carbon atoms in common. These com- pounds, which correspond to the condensed benzenic compounds (p. 385), include the indole, quinoline, authraquinoline, quinquino- line, and diphenylene derivatives. C. Compounds containing two (or more) nuclei, one at least hete- rocyclic, united directly without fusion, corresponding to the di- phenyls, and including phenyl-pyridyl, dipyridyl, pyridyl-pyrrole, and pyridyl-piperidyl derivatives. D. Compounds containing two (or more) nuclei, one at least heterocyclic, united by aliphatic groups, corresponding to the diphenyl-paraffms, and including the " ester-alkaloids" such as atropine, cocaine, etc. In a more detailed classification the members of the several classes are subdivided into the groups, of mono-, di-, tri-, and tetrahetero- atomic compounds, according as they contain one, two, three or four atoms other than carbon, of like or different kinds, in the ring. A. MONONUCLEATE HETEROCYCLIC COMPOUNDS. FIVE MEMBERED RINGS. The parent substances of these compounds are furfurane, thio- phene, and pyrrole (see p. 390). The heterocyclic rings differ from the carDocyclic in that the several carbon atoms are not equal in value, and therefore two dif- ferent monosubstituted deriva- tives exist for the five-membered / y \\ rings containing a single hetero- /S'HC CH/J atom, such as furfurane, and H [] (J H three such compounds in six- a'\ // a membered rings, such as pyri- dine, according to the position Pyridine. ' . * v, of substitution with reference to the hetero-atom. These positions are distinguished by the first three letters of the Greek alphabet, as shown in the margin, or, sometimes by numbers. The positions and ', and and ft' are of equal value. 392 TEXT-BOOK OF CHEMISTRY HC=CH\ Furfurane 1 exists in the product of distillation of HC=CH/ pine and fir wood, and is also formed by distillation of barium pyro- HC CH 2 \ mucate (below), and from dihydrofurfurane, 0, a product HC-CH 2 / of reduction of erythrol (p. 224). It is a liquid; b. p. 32; having a peculiar odor. Its vapor colors a pine shaving moistened with HC1 green (pp. 346, 393). HC=C CHO a-Furfuraldehyde Furfurole Furfural Furole HC=CH O is produced by the dry distillation of sugar or of wood; by the dis- tillation of these substances, or of bran, carbohydrates or glucosides with dilute H 2 S0 4 ;; by the action of the concentrated acid upon car- bohydrates; and by distilling pentoses (p. 247), or glucuronic acid (p. 266) with HC1. It is a colorless liquid; agreeable in odor; b. p. 162; soluble in water and in alcohol. Being an aldehyde, it under- goes the reactions common to those substances. In concentrated solution, with urea and a trace of acid, it is colored yellow, changing to blue, to violet and to purple, and finally fading, with formation of a black precipitate (Schiff's reaction). It produces a red color with aniline, a very sensitive reaction for its presence. Paper moist- ened with aniline acetic solution is used. Pettenkof er 's reaction for the biliary salts, etc., depends upon the formation of furfurole. HC=C COOH a-Furfurane Carboxylic Acid Pyromucic acid HC=CH the acid corresponding to furfurole, is produced from that sub- stance by oxidation, also by distillation of mucic and isosaccharic acids (p. 265). It is a solid; f. p. 134. HC=CH\ Thiophene | S and its superior homologues, methyl- HC=CH/ thiophenes, etc., occur in gas-tar, and accompany the various prod- ucts, benzene, etc., obtained from it. It is a colorless liquid; b. p. 84; which is so nearly that of benzene, 80.5, that the two sub- stances cannot be separated by distillation. With sulphuric acid and isatine it gives a fine color, due to formation of indophenine. Sulphuric acid alone is colored brown by thiophene, which it absorbs ; and thiophene may be recovered from the solution by neutralization and distillation. HC=CH\ Pyrrole I NH exists in coal-tar and accompanies the HC=CH/ pyridine bases (p. 397) in oil of Dippel. It is formed in a great variety of reactions, as by the action of baryta at 150 upon albumins, by the dry distillation of gelatin or of ammonium saccha- rate, etc. It is a colorless, oily liquid, having the odor of chloro- form; b. p. 131. Being a secondary amine, it has. basic properties, FIVE MEMBERED HETEROCYCLIC RINGS 393 and its imide hydrogen is readily replaced by other atoms or groups. A pine shaving moistened with HC1 is colored flame-red by pyrrole (the pine-shaving reaction; see also, Phenol, p. 346). It also yields an indigo-blue color with H 2 S0 4 and isatine. Heated with dilute acids it gives off ammonia, and a red powder (pyrrole red) is deposited. The homologous pyrroles, methyl-pyrroles, etc., have reactions similar to those of pyrrole. Hydropyrrole Derivatives Nascent hydrogen combines with CH :CH \ pyrrole to form, first dihydropyrrole, or pyrroline, I NH, CH 2 .CH 2 / an alkaline liquid, soluble in water; b. p. 91; and, finally, tetra- CH 2 .CH 2 \ hydropyrrole, or pyrrolidine, or tetramethylene-imine, I NH, which bears the same relation to pyrrole that piperidine does to pyridine (p. 398). Pyrrolidine resembles piperidine in its reactions, and also forms an addition product with methyl iodide. It is formed by heating tetramethylene-diamine hydrochloride : H 2 N. ( CH 2 ) 4 .NH 2 .HC1=NH 4 C1+ ( CH 2 ) 4 :NH and constitutes the nucleus of the hygrines and one of those of nicotine. It is a strongly alkaline liquid; b. p. 87. Among the derivatives of pyrrolidine is pyrrolidone, or butyrolactam, CH 2 .CH 2 \ NH, a simple cyclic imide derived from ^-amidobutyric CH 2 .CO/ acid. a Pyrollidine Carboxylic Acid Proline is a product of hydroly- sis, by HC1 or by tryptic digestion, of casein and gelatin, in which it probably exists as a dipeptide, constituted by substitution of the radical of tf-amido-isocaproic acid for the imide hydrogen of the cyclic compounds : H 8 C\ /CH 2 .CH 2 CH.CH 2 .CH.CO.N | H 2 N HOOC/ CH - CH2< AZOLES AND THEIR DERIVATIVES. The azoles are derivable from furfurane, thiophene and pyrrole by substitution of one or more N atoms for methine groups in the five-membered ring. They are distinguished, according to their parent substances, into furazoles, thioazoles, pyrroazoles and selen- azoles, there being nine possible of each class, or they may be con- sidered as derived from pyrrole by substitution of further hetero atoms in the ring. They are further distinguished as monazoles, dia- zoles, triazoles and tetrazoles, according to the number of intro- duced N atoms. Thus the formulas of pyrrole and of the nine pyrro- azoles are: 394 TEXT-BOOK OF CHEMISTRY HC- H iJ CII \ / N H Pyrrole. [JHC - CH[ 3 ] [ 5 ]HC N[ 2 ] \ / N[J H a-Monazole. H HC CH HC N J Jl HC U \ / \ / N N H H a-a' Diazole. a-/3-Diazole. N N i\^ J.TI N CH AAV> -L'* J N N 1 TI ia J U* II II N N \ / \ / \ / \ / N N N N H H H H a'-0 -Diazole. a'-a-/3-Triazole. a-/3-/3'-Triazole. Tetrazole. \ / N H /3-0' -Diazole. Corresponding to each of these compounds there are numerous derivatives, formed by substitution, or by modification of internal linkages and addition. Antipyrine i-Phenyl-2,3-dimethyl Pyrazolon (formula below) is formed, as its hydroiodide, by heating 1, 3-phenylmethyl pyra- zolon, with methyl iodide and methylic alcohol to 100 in sealed vessels. In this reaction the I-pyrazolon type is maintained in the product of addition, but on splitting off HI to liberate the free base the antipyrine type is produced : H 2 C C. O.J II \/ N C e H 8 l-phenyl-3-metbyl pyrazolon. H 2 C C.CH 3 II/CH. OC N\I \/ N C 6 H 6 lodomethylate. HC = C.CH 3 OC N.CHs N C a H 5 Antipyrine. Antipyrine forms colorless, odorless scales, somewhat bitter in taste ; f . p. 110.5 . A mixture of equal parts of antipyrine and anti- febrin (f. p. 112.5) fuses at 45. Antipyrine is readily soluble in water, alcohol and chloroform, less soluble in ether. With nitrous acid or the nitrites (sp. seth. nitr.), in the presence of free acid, it forms a green, crystalline, sparingly soluble nitro-derivative, which is poisonous. Its solution is colored deep red-brown by FeCl 3 , the color being discharged by H 2 S0 4 . Nitrous acid colors its solutions bright green, and on heating the mixture, after addition of a drop of fuming nitric acid, the color changes to light-red, then to blood- red, and finally a purple oil is deposited. Addition of a drop of fuming nitric acid to cold, concentrated solution of antipyrine causes precipitation of small, green crystals. Antipyrine is strongly basic, and some of its salts are used in medicine : Salipyrine is antipyrine salicylate. It is formed by the action of the acid and the base upon each other at 100. It is a white, crystalline powder, almost in- soluble in water. FIVE MEMBERED HETEROCYCLIC RINGS 395 Tolypyrine i-toluyl- 2, 3-dimethyl pyrazolon is obtained in the same manner as antipyrine, using p-toluyl-hydrazine in place of phenyl-hydrazine and contains toluyl, C 6 H 4 .CH 3 in place of phenyl. It forms colorless crystals ; f . p. 136 ; and has a physiological action similar to that of antipyrine. HydantoVn, Glycolylurea 2, 5-diketotetrahydroglyoxalin (formula below) is the simplest of the cyclic monureides (p. 316), and is formed by the action of HI upon allantoi'n, or upon alloxanic acid. It is converted into the corresponding open chain compound, hydantoic, or glycoluric acid, H 2 N.CO.NH.CH 2 .COOH, by heating withBa(OH) 2 . Corresponding to hydantoi'n are a number of substituted hydan- toi'ns, constituted by substitution of alkyls for H in the several posi- tions. The /^-compounds are formed by heating the monoalkyl amido- acids with urea. Thus urea and sarcosine yield (3 -methylhy dantoin * /CO.N.CH, H 2 N.CO.NH 2 +CH 2 (NH.CH 3 ) .COOH=HN +N H 3 +H 2 \CO.CH 2 OC CO OC CO OC CO OC CO \/ \/ \/ \/ N N N N H H H H Hydantoin. Allantoin. Allanturic acid. Oxalylurea. Allantoin, Glyoxyldiureide (formula above) a derivative of hydantoi'n, occurs in the allantoic fluid of the cow, in the urine of sucking calves, of dogs and cats fed on meat, of children during the first few days of life, of adults after administration of tannin, and of pregnant women ; also in beet juice. It is also formed during autoly- sis of pancreas, liver and spleen. It is obtained by oxidation of uric acid by lead peroxide: 2C 5 H 4 N 4 3 +2H 2 0+0 2 =2C 4 H 6 N 4 3 +2C0 2 Or, synthetically from glyoxylic acid and urea: /CO.NH m CHO.COOH+2H 2 N.CO.NH 2 =HN | +2H 2 \CO.CH.HN.CO.NH 2 It crystallizes in prisms, sparingly soluble in cold water, readily soluble in hot water and in alcohol. On reduction by HI it yields hydantoi'n and urea. Heated with alkalies it is decomposed into am- monia and carbonic, oxalic and acetic acids ; glyoxylic acid being prob- ably first formed and decomposed. Warmed with Ba(OH) 2 , or with Pb0 2 , it splits off urea and forms allanturic acid (formula above). Oxalylurea, Parabanic Acid 2, 4, 5-triketotetrahydroglyoxalin (formula above) is formed by oxidation of uric acid or of alloxan 396 TEXT-BOOK OF CHEMISTRY by HN0 3 ; or synthetically by the action of POC1 3 or PC1 3 on a mix- ture of oxalic acid and urea: /CO.NH COOH.COOH+H 2 N.CO.NH 2 r=HN +2H..O \CO.CO Its salts are converted into oxalurates by water. Histidin C 6 H 9 N 3 2 one of the hexon bases, is produced by hydrolysis of proteins. It crystallizes in rhombic plates or needles, is sparingly soluble in water, insoluble in alcohol and ether and is dextrorotary. It is only faintly alkaline, but expels C0 2 from Ag and Cu carbonates. By oxidation by KMn0 4 in alkaline solution it yields HCN, C0 2 and NH 3 , but it is not attacked by KMn0 4 +H,S0 4 . When boiled with Ba(OH) 2 it does not give off NH 3 . It does not give the biuret reaction. It contains two H atoms replaceable by metals, and it forms two series of salts with acids. Nitrous acid separates one N atom as free nitrogen, and it forms one substitution product with fi -naphthalene sulphonic acid; but two of its N atoms are capable of salt formation. It therefore contains one NH, and one NH, and the third N is tertiary. When heated it gives off C0 2 , and leaves a com- pound C 5 H 7 N 2 .NH 2 , and therefore it contains a COOH. The small proportion of H indicates a closed chain nucleus, and its reactions indicate two double linkages in the ring. It gives the Weidel reac- tion faintly. When diazobenzene-sulphonic acid (C 6 H 5 .N:N.S0 3 H, or sulphanilic acid and KN0 2 : the diazo reaction) is added to a solu- tion of histidin in Na 2 C0 3 , a coloring matter is formed which is orange in acid solution and dark cherry-red in alkaline solution. The only other product of protein hydrolysis which gives this reaction is tyrosin. Histidin is a derivative of glyoxaline, whose constitution //CH.NH is probably N , ft. glyoxaline of. amido-pro- \CH :C.CH 2 .CHNH 2 .COOH pionic acid. SIX MEMBERED RINGS. Six membered heterocyclic compounds are known, containing oxygen, sulphur and nitrogen in the nucleus: H H 2 H H 2 C C C C N II \ /\ /\ /\ /\ HC CH HC C.CH 3 HC CH H 2 C CH 2 HC CH oci HH M II HC CH nil C!H H 2 C CH 2 1 1 ( ' 1 1 \/ \ II \ II \/ \ II o S N N N H o-Pyrone. 0- Methylpenthiophene. Pyrldlne. Plperldlne. Pyrazlne. The oxygen and sulphur compounds are neither numerous nor important. Some of the former are products of condensation of ali- phatic compounds, tf-lactones and tf-anhydrides. SIX MEMBERED HETEROCYCLIC RINGS 397 Pyrone (y) Pyrocomane \rijZ c.g;* CO is an oxidized derivative of y furane, produced from comenic acid by the action of heat and constituting the nucleus of comenic, chelidonic, and meconic acids. Comenic acid C 5 H 2 O 2 ( OH ) .COOH is produced by the action of hot H 2 0, of dilute acids, or of bromine water upon meconic acid. It crystallizes in yellowish prisms, rather soluble in H 2 0. It is monobasic. It is decomposed by heat into C0 2 and pyrone. Chelidonic acid C 5 H 2 O 2 ( COOH ) 2 exists in chelidonium, in combination with the alkaloids sanguinarine and chelidonine. It is a crystalline solid and a dibasic acid. Heat converts it into comenic acid, which in turn yields pyrone. Meconic acid C 5 HO 2 (OH) (COOH) 2 is 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; quite soluble in water, soluble in alcohol, sparingly soluble in ether. With ferric chloride it forms a blood-red color, which is not discharged by dilute acids or by mercuric chloride; but is discharged by stannous chloride and by the alkaline hypochlorites. PYRIDINE BASES AND THEIR DERIVATIVES. The pyridine bases, closely related to the vegetable alkaloids (p. 419) as well as to some of the basic substances formed during putre- faction, were first obtained from oil of Dippel, or bone-oil (Oleum animale), an oil produced during the dry distillation of bones, horns, etc., and as a by-product in the manufacture of ammoniacal com- pounds from those sources. They also occur in coal-tar, naphtha, commercial ammonia, methylic spirit and fusel oil. They are formed synthetically: (1) By heating the aldehyde-ammonias alone, or with aldehydes or ketones; (2) From pyrrole by the action of K or Na in presence of methylene iodide, etc.; (3) By oxidation of hexa- hydropyridines, piperidines; also by other methods. The pyridine bases are colorless liquids of peculiar, penetrating odor. The superior homologues are metameric with the anilines. They are strong triacid bases, and behave like tertiary monamines. Oxidizing agents do not attack pyridine, nor the nucleus of its supe- rior homologues, but the lateral chains of the picolines, etc., are readily oxidized, with formation of carbopyridic acids. Reducing agents convert them into piperidines (p. 398). They react with sev- eral of the general reagents for the alkaloids (p. 421). The two most nearly characteristic properties of the pyridine bases are: (1) the formation of chloroplatinates such as (C 5 H 5 N.HCl) 2 PtCl 4 , which on boiling with water, lose two molecules of HC1 to form " modified salts" such as (C 5 H 5 N) 2 PtCl 4 (Anderson's reaction), and, (2) the formation of crystalline addition products, alkyl-pyridinium iodides, such as C 5 H 5 N<^ HiJ on contact of their alcoholic solutions with alkyl iodides. Pyridine HC/H:CH\ N _ is obtained from oil of Dippel, or from piperidine. It boils at 115, mixes with water in all proportions, 398 TEXT-BOOK OF CHEMISTRY is strongly alkaline in reaction. Its hydrochloride is crystalline, but deliquescent. Its chloroplatinate fuses at 240. When reduced by sodium and alcohol, it forms piperidine, or hexahydropyridine ; and when reduced by hydriodic acid, normal pentane, CH 3 .CH 2 .CH 2 .- CH 2 .CH 3 . Pyridine Homologues Alkyl Pyridines are substitution prod- ucts containing alkyl groups for H. Owing to the inequality in value of the several C atoms of pyridine (p. 397), the number of substituted derivatives is greater than with benzene. There are three monosubstituted derivatives, six each of the bi- and tri-sub- stituted, three tetra-, and one penta-substituted. Methyl-pyridines Picolines C 5 H 4 N(CH 3 ) The three pico- lines, a, ft and y, exist in oil of Dippel, and have been formed syn- thetically. Their b. p.'s are 130, 143, and 144. Lutidines Three ethyl pyridines, C 5 H 4 N(C 2 H 5 ), are known, or, b. p. 148, yff, b. p. 166; and y, b. p. 165. Of the six possible dimethyl-pyridines, C 5 H 3 N(CH 3 ) 2 , four are known, three of which exist in bone oil. Collidines CgH^N There are twenty-two possible collidines, of which twelve are known. Of these several are products of decom- position of vegetable alkaloids, or exist in oil of Dippel, or are pro- duced during putrefaction. Hydropyridines Piperidines are compounds produced from the pyridines by the action of nascent hydrogen. Dihydropyridines and tetrahydropyridines are known, the latter known as piperideines, but by far the most important of the group is Piperidine Hexahydropyridine H 2 C \c! 2 2 'cH 2 2 / NH ~~ which is produced by saponification of piperine by heating with alcoholic KOH, and is also formed by reduction of pyridine, or by heating pentamethylene-diamine hydrochloride. It is a colorless liquid; b. p. 106 ; having an odor like that of pepper ; readily soluble in water and in alcohol. Oxidizing agents rupture the piperidine ring, with formation of aliphatic compounds. When heated with methyl iodide it is converted into methylpiperidine hydroiodide, H C /CH 2 .CH 2 \ N //HI n *^ \CH 2 .CH 2 / w \CH 8 .* Piperidine and methyl-piperidine are particularly of interest as being the nuclei of a number of vegetable alkaloids. Thus coniine is a propyl-piperidine, and tropine and ecgonine, the basic nuclei of the atropic and cocaine alkaloids, are derivatives of methyl-piperi- dine (see pp. 425, 427). AZINES AND THEIR DERIVATIVES. The azines are compounds bearing the same relation to pyridine that azoles bear to pyrrole (p. 393), i.e., they are derived from pyri- dine by substitution of further hetero-atoms in the ring. Oxygen, SIX MEMBERED HETEROCYCLIC RINGS 399 sulphur and nitrogen are the only elements known to enter into such ring formation. When but one hetero-atom exists in the ring in addition to the pyridine N, the substance is a derivative of an oxazine if it is 0, of a thiazine if it is S, and of a diazine if it is N; and there are three of each class, ortho, meta and para. Nuclei also exist containing more than two hetero-atoms, 0, S, or N, in a six mem- bered ring, and, as these may be like or unlike, such compounds are very numerous and of great variety. The oxazines and thiazines are only known in their derivatives. Diazines. There exist three isomeric diazines ortho, meta and para which are thin, colorless oils, soluble in water, alcohol and ether, insoluble in petroleum ether, neutral in reaction: H H COOH H C C N C N /4\\ /4\\ /\\ /\\ /\ HC5 3CH HC5 3N HC CH HOOC.C CH H 2 C CH 2 HC6 2N HC6 2CH HC CH HC N H 2 C CH 2 \l// \l// \ II \ // \/ N N N N N H Orthodlazine. Metadiazine. Paradlazine. 4,5-orthodiazine Hexahydro- Pyridiazine. Pyrimidine. Pyrazine. dlcarboxylic acid. pyrazine. Orthodiazine Pyridiazine is obtained by heating the 4, 5-dicar- boxylic acid (formulas above): C 4 H 2 N 2 (COOH) 2 =C 4 H 4 N 2 +2C0 2 , which is itself obtained from the tetracarboxylic acid, a product of oxidation of phenazone (below). It has a pyridine-like odor, b. p. 208. Forms an insoluble, crystalline compound with AuCl 3 . Metadiazine Pyrimidine is obtained by starting from 4-methyl- uracil. This is first converted by POC1 3 into 4-methyl-2, 6-dichlor- pyrimidine, which is then reduced by zinc dust to 4-methylpyrimi- dine, which is then oxidized to the carboxylic acid, and this is de- composed by heat into pyrimidine and carbon dioxide: HC Pyrimidine-4- Pyrimidine. carboxylic acid. The free base is an oil, b. p. 124, having a penetrating, narcotic odor, which forms a nitrate and a hydrochloride, both of which are completely volatile below 100. It forms crystalline compounds with HgCl 2 , AuCl 3 , and picric acid, but not with CuS0 4 . Paradiazine Pyrazine is obtained by condensation of amido acetaldehyde by mercuric chloride : 400 TEXT-BOOK OF CHEMISTRY It has a faint heliotrope odor. B. p. 118. From concentrated aqueous solution it deposits crystals, f. p. 53, which are extremely volatile. It forms a crystalline compound with CuS0 4 . Pyrazine and its homologues are produced during fermentation, and exist in fusel oils and in commercial amylic alcohol. Hexahydro - pyrazine Piperazine Diethylene Diamine HN.CH,.CH 2 may be obtained by reduction of para-diazine, but is HjC.CH2.NH manufactured from diphenyl-diethylene diamine, CJEL.N ^SS^SS 2 ^ \{jtl 2 .L,a. 2 / N.CeH 5 , which is obtained by the action of ethylene bromide upon aniline. It crystallizes in colorless needles; f. p. 104; b. p. 145; soluble in water, and deliquescent. It is strongly alkaline and basic, and absorbs carbon dioxide from air. It forms a soluble compound with uric acid and is used medicinally as a solvent for uric acid in lithiasis. Pyrimidine Derivatives. The pyrimidine, or myazine compounds which are of medical interest are not referable directly to pyrimi- dine, or metadiazine itself, but to the hydropyrimidines (formulae below), of which they are ring ketone derivatives, most of which con- tain the grouping N.CO.N, which also exists in urea. They include uric acid and its derivatives, the xanthine bases, and most of the cyclic ureides (p. 316). They are divided into two groups: I. Compounds containing a single hydropyrimidine ring, more or less modified by substitution. This class includes: (a) The uracil group, (b) The malonylurea group, (c) The guanides. II. The purine group. Compounds containing a hydropyrimi- dine nucleus with a glyoxaline ring fused upon it. These compounds would be more properly classified among the condensed heterocyclic compounds (p. 414), but are more conveniently considered here. The positions of orientation in the pyrimidine ring have been designated in several different ways, which has led to no little con- fusion. The notation which will be adopted here is that in which numbers are used, and in which the two nitrogen atoms occupy the 1 and 3 positions, as in the following formula? of pyrimidine and of uracil : H(4) H H H a C C C C /\\ /\\ //\ /\ (1)HN CO (6) (5)HC N(3) (6)HC CH(2) \// H 2 C N H a C CH \// HC NH H,C CH, \/ H 2 C NH H 2 C CH a \/ (2) OC CH(5) (3)HN CH(4) N N N N (1) H H Pyrimidine. Al, 3-Dihydro- A 4-Tetrahydro- Ilexahydro- 2, 6 M-Diketotet- pyrimldine. pyrimidine. pyrimidiue. rahydropyrlm- idine (Uracil). SIX MEMBERED HETEROCYCLIC RINGS 401 While the above hexagonal expressions are most in conformity with those of other cyclic compounds, and are on that ground prefer- able to ^the quadrilateral expression of the formula of uracil, the latter form was adopted for the uracyl, uric acid and xanthine deriva- tives before their relationship to pyrimidine was recognized, and have since come into such universal use that we feel reluctantly compelled to make use of them for these compounds. I a. The Uracil Group. The physiologically interesting members of this group are 2, 6-diketo derivatives of the unknown tetrahydro- pyrimidine, sometimes referred to as oxypyrimidine derivatives, a term which more properly applies to compounds containing a phenolic or secondary alcoholic OH as a lateral chain. Uracil C 4 H 4 N 2 2 2, 6- A 4-diketotetrahydropyrimidine was first obtained as a product of decomposition of yeast-nucleic acid, and later from other nucleic acids. It is also formed from thymine in autolysis of pancreas, and is probably widely disseminated in animal organisms. It has been obtained synthetically: Hydrouracil, the corresponding hexahydropyrimidine derivative, is first* obtained, either by heating together urea and /?-amidopropionic acid : HN.CO.NH H 2 N.CO.NH 2 +CH 2 NH 2 .CH 2 .COOH:= | I +NH 3 +H 2 O OC.CH 2 CH 2 or, more readily, from urea and acrylic acid: HN.CO.NH H 2 N.CO.NH 2 +CH 2 :CH.COOH= | I +H 2 OC.CH 2 .CH 2 This latter reaction constitutes a general method of synthesis of uracil derivatives, starting from various unsaturated acids, known as Fischer and Boeder's method. The hydrouracil is then converted into a bromine derivative, which is debrominated by pyridine : HN.CO.NH C 4 H 5 N 2 2 Br+C 5 H 5 N= o( j CH ^ H +C 5 H 5 NHBr Another general method of synthesis of the uracil compounds is that of Wheeler and Johnson, based upon the fact that alkylpseudo- thioureas readily condense with ketonic acid esters to form alkyl- mercaptoketopyrimidines, which are split by boiling with HC1 or HBr to ketopyrimidines and mercaptan. Thus ethylpseudothiourea and sodium formylacetic ester condense to 2-ethylmercapto-6-keto- pyrimidine, which is decomposed by HBr to uracil and mercaptan: HN.C(S.C 2 H 5 ):N HN :C \S.C 2 H 6 +NaO.CH :CH.COO( C 2 H 5 ) = +C 2 H 5 .OH+NaOH, and HN.C(S.C 2 H 5 ) :N HN.CO.NH CO.CH = 402 TEXT-BOOK OF CHEMISTRY Uraeil crystallizes in rosettes of needles, easily soluble in hot water, difficultly in cold water, almost insoluble in alcohol and ether, easily soluble in ammonia. It does not form compounds with HC1 or HN0 3 , nor a ppt. with phosphotungstic acid. With AgN0 3 alone it does not ppt., but on addition of NH/)H a gelatinous ppt. is formed, soluble in excess. It also forms a ppt. with Hg(N0 3 ) 2 . It gives the Weidel reaction, which consists of the production of a red or purple color when chlorine water and a trace of HN0 3 are evaporated with the substance, and the residue is exposed to ammonia. This reaction is characteristic of certain pyrimidine compounds (see Xanthine, p. 410). Two methyluracils are known. 4-Methyluracil (formula p. 403) the earliest known of the uracil compounds, is formed by the condensation of acetoacetic ester with urea : HN.CO.NH CH 3 .CO.CH 2 .COO(C 2 H 5 )+H 2 N.CO.NH 2 = I I + OC.CH : C.CHg C 2 H 5 .OH+H 2 a reaction which constitutes one of the steps in a synthesis of uric acid (p. 406). It is also formed by Fischer and Boeder's method by starting from crotonic acid, CH 3 .CH :CH.COOH ; and by Wheeler and Johnson's method by starting from methylpseudothiourea and acetoacetic ester. It crystallizes in needles from hot water, and is difficultly soluble in alcohol. It dissolves in NaOH or KOH, form- ing crystallizable salts. By further methylation it yields dimethyl- and trimethyl-uracil. It also forms chlorine, nitro, amido and phenyl derivatives, and carboxylic acids. Thymine 5-Methyluracil (formula p. 403) is a product of decomposition of thymus-nucleic acid. It is formed synthetically by Fischer and Boeder's method, starting from methyacrylic acid, CH 2 :C(CH 3 ).COOH; and by Wheeler and Johnson's method, start- ing from methylpseudothiourea and sodium formylpropionic ester, 8 Q/C.COOH. It crystallizes in quadratic or six-sided prisms; fuses and sublimes at 250 ; is difficultly soluble in cold water, easily in hot water, less soluble in alcohol and ether. It is neither distinctly acid nor basic. Its aqueous solution ppts. with Hg(N0 3 ) 2 ; with HgCl 2 only after addition of NaOH to slight alkalinity, and with AgN0 3 only after addition of NH 4 OH. It decolorizes bromine water. On nitration and subsequent reduction it yields a compound which gives the Weidel reaction. It is pptd. by phosphotungstic acid. 4-Phenyluracil C 4 H 3 N 2 2 .C H 5 is formed by condensation of urea and benzoylacetic ester, CH 2 (CO.C 6 H 5 ).COO(C 2 H 5 ) ; by Fischer and Boeder's method, starting from cinnamic, or /ff-phenylacryli<3 acid, CH(C 6 H 5 ) :CH.COOH; and by Wheeler and Johnson's method, starting from methylpseudothiourea and sodium benzoylacetate. 5- Phenyluracil is also known. SIX MEMBERED HETEROCYCLIC RINGS 403 Cytosine 6-amido- 2 keto - A 4, 6-dihydropyrimidine (formula below) obtained from thymus-imcleic acids, herring and sturgeon melt, pancreas, yeast and wheat, is not properly a uracil derivative, as it does not contain two CO groups, and it is a dihydro pyrimidine, not a tetrahydropyrimidine, derivative. It is obtained synthetically by Wheeler and Johnson's method: 2-ethylmercapto-6-ketopyrimidine is obtained as described above (uracil). This is then converted by PC1 5 into 2-ethylmercapto-6-chlorpyrimidine, which with* alcoholic ammonia produces 2-ethylmercapto-6-amidopyrimidine : N.C(S.C 2 H 5 ) :N N.C(S.C 2 H 5 )':N and this is split by HBr into cystosine and mercaptan : N.C(S.C 2 H 5 ):N N.CO.NH || | +H 2 0= | +C 2 H 5 .SH CNH 2 .CH=CH H 2 N.C.CH:CH Cytosine crystallizes in pearly plates, difficultly soluble in water. It forms a hydrobromide, chloroplatinate, picrate, nitrate and two sulphates, which are all crystalline. It is pptd. by phosphotungstic acid, by AgN0 3 , and by Ba(OH) 2 in excess. It gives the Weidel re- action, although it contains but one CO. Nitrous acid converts it into uracil: C 4 H 5 N 3 0+HN0 2 =C 4 H 4 N 2 2 +N 2 +H 2 as guanine is converted into xanthine, and adenine into hypo- xanthine (p. 411). When oxidized by BaMn 2 8 it yields biuret and oxalic acid: C 4 H 5 N 3 0+H 2 0+20 2 =C 2 H 5 N 3 2 +C 2 4 H 2 The relations of the uracils and cytosine are shown in the follow- ing formulae: HN CO HN CO HN CO N=C.NH 2 OC CH OC CH OC C.CH 3 OC CH HN CH HN C.CH 3 HN CH HN CH Uracil. 4-Methyluracil. Thymine. Cytosine. 11} . The Malonylurea Group. The members of this group are tri- or tetraketo-hexahydropyrimidine compounds, all of which are derivable from malonylurea by substitution in the CH 2 group of malonic acid. The three principal members of the group are : HN CO HN CO HN CO II II II OC CH 2 . OC CHOH OC CO HN CO HN CO HN CO Malonylurea. Tartronylurea. Mesoxalylurea. 404 TEXT-BOOK OF CHEMISTRY Malonylurea Barbituric Acid 2, 4, 6-Triketohexahydropy- rimidine C 4 H 4 N 2 O 3 is produced by the action of POC1 3 upon a mixture of urea and malonic acid: HN.CO.NH 3H 2 N.CO.NH 2 +3COOH.CH 2 .COOH+2POC1 3 =3 \ OC.CHj.CO +2P0 4 H 3 +6HC1 It is also formed by the action of concentrated H 2 S0 4 on allox- antin (below). It crystallizes with 4 Aq., is efflorescent, sparingly soluble in cold water, readily soluble in hot water. It behaves as a dibasic acid. It is decomposed by boiling alkalies : C 4 H 4 N 2 3 +3H 2 0=COOH.CH 2 .COOH+2NH 3 +C0 2 In malonylurea the hydrogen atoms of the CH 2 group exhibit the same mobility that they do in malonic ester, and are replaceable by sodium, which is in turn replaceable by alkyls. Thus dimethyl- malonylurea, OC^^CO/^ 01 ^' mav be Pduced either by the successive action of Na and CH 3 I upon malonylurea, or by the action of POC1 3 upon urea and dimethylmalonic acid. The last named acid is produced when dimethylmalonylurea is hydrolyzed by KOH. Dimethylmalonylurea is isomeric with malonyldimethylurea, OC \N(CH 8 8 )'.CO/ CH 2 obtained by the action of POC1 3 upon malonic acid and dimethylurea. Diethylmalonylurea, OC^l;o/ C ( C 2H 5 ) 2 , is similarly obtained, and has been used as a hypnotic under the name veronal. Tartronylurea Dialuric Acid 2, 4, 6-triketo-5-oxyhexahydro- pyrimidine C 4 H 4 N 2 4 is produced, along with oxaluric acid by reduction of alloxan, it containing a secondary alcoholic group in the 5 position, where alloxan contains a ketone group (formulae p. 403). It is converted by nitrous acid into allantoin. By exposure to air and moisture tartronylurea forms alloxantin, C 8 H 4 N 4 7 , in which reaction probably one molecule of tartronylurea is oxidized to alloxan, which condenses with a second molecule of tartronyl- urea. Alloxantin is also formed by reduction of alloxan, and by oxidation of uric acid. It forms sparingly soluble crystals, which turn red on exposure to air. Murexide is the ammonium salt of the unknown purpuric acid, C 8 H 5 N 5 6 , derived from alloxantin by sub- stitution of NH for 0, and, like that substance, containing two hydropyrimidine nuclei. It is produced by heating alloxantin with NH 3 , or by evaporating nitric acid on uric acid, and adding ammonia to the residue (murexide test, p. 408). The product of the Weidel reaction, in which chlorine water with a trace of HN0 3 is used as an oxidant (p. 402), is also probably murexide. Murexide crystallizes in short, red prisms, having a greenish reflection, and forming a red SIX MEMBERED HETEROCYCLIC RINGS 405 powder when ground. It is difficultly soluble in cold water, insoluble in alcohol and ether. Allpxan Mesoxalylurea 2, 4, 5, 6-Tetraketohexahydropyrimi- dine C 4 H 2 N 2 4 is a product of the limited oxidation of uric acid, alloxantin, or murexide. Uric acid oxidized by dilute HN0 3 at 60 to 70 yields alloxan and urea : HN.CO.C.NH\ HN.CO.NH I CO+H 2 0+0= I | +H 2 N.CO.NH 2 OC.NH.C.NH/ OC.CO.CO It has been found in the intestinal mucus in diarrhea. It forms prismatic crystals, readily soluble in water, which turn red in air, are acid in reaction, and stain the skin red. Reducing agents con- vert it into alloxantin ; and by oxidation it yields oxalylurea, : HN.CO.NH HN.CO\ I | +0= I NH+C0 2 OC.CO.CO OC.CO/ When heated with Ba(OH) 2 the cyclic nucleus is broken, and alloxanic acid is formed: HN.CO.NH I | +H 2 0=H 2 N.CO.NH.CO.CO.COOH OC.CO.CO Ic. The guanides are derivatives of malonylguanide, which is 2-imido-4, 6-diketohexahydropyrimidine, and is formed by the interaction of guanidine and malonic ester : TT\T r JTT /NH 2 p COO(C 2 H 5 ).CH 2 .COO(C 2 H 5 )+HN:C HN - CO HKC(NH).NH Malonylguanide. | + 2C 2 H 5 .OH OC.CH 2 CO The derivatives are formed, as are those of malonic ester, and of malonylurea, by substitution in the CH 2 group. II. The purine group. The compounds of this group, which in- cludes uric acid, the xanthine bases, caffeine, etc., are derivatives of purine, whose molecule consists of a pyrimidine ring, with a glyoxalin ring fused upon it at the 4 and 5 positions : N=CH (1)N=CH(6) HC C N (2)HC 0(5) NH(7) II II >* II II N C NH (3)N 0(4) the last of which is the formula now generally adopted. Some of the derivatives are referable to purine itself, others to the methylpurines, in which CH 3 is substituted for H in one or more of the positions, 2, 6, 8, and 7 or 9. 406 TEXT-BOOK OF CHEMISTRY Purine C 5 H 4 N 4 is obtained by starting from uric acid (1). This is converted by POC1 3 , first into 8-keto-2, 6-dichlorpurine and then into 2, 6, 8-trichlorpurine (2). By the action of HI and PHJ this is converted into 2, 6-diiodopurine (3), which by boiling with zinc in an atmosphere of C0 2 yields purine (4) : HN CO OC C.NH\ N=CC1 C1C C.NH\ N=CI 1C C.NH\ N=CH HC C.NH\ 1 II co HN C.NH/ II M CC1 N C . N // It. II CH -C . N // UCH .N// (1) (2) (3) (4) Purine crystallizes in small needles, f. p. 212, very soluble in cold water and in warm alcohol. It is neutral in reaction, but forms salts with both acids and bases. Its solutions ppt. with AgN0 3 , phosphotungstic acid and tannin; not with KI, Nessler's reagent or K 4 Fe(CN) . It withstands oxidizing agents. Its reaction with Br is characteristic; in its solution in concentrated HC1, Br forms a fine reddish yellow, crystalline mass, soluble on warming, and crystalliz- ing again on cooling. Uric Acid Lithic Acid 2, 6, 8-Triketopurine (formula 1, above), C 5 H 4 N 4 3 occurs in the urine of man and of the carnivora, in combination, chiefly as its disodic salt; in the urine of the herbi- vora, in which ordinarily it is replaced by hippuric acid, when, in early life and during starvation, they are, for the time being, prac- tically carnivora; in some urinary calculi, in the so-called "chalky deposits," or "tophi," in the joints of the gouty; very abundantly in the excretions of serpents, tortoises, birds, molluscs and insects, and in guano ; in smaller amount in the blood and tissues. It is best obtained from guano or from the solid urine of serpents, which con- sists almost entirely of ammonium urate. Uric acid is obtained synthetically: (1) From monochloracetic acid and urea. Monochloracetic acid is converted into malonic acid; this is then condensed with urea to malonylurea (5 below) ; this by HN0 3 to nitromalonylurea (6) ; this by reduction to amidomalonyl- urea (7) ; this by condensation with urea to pseudouric acid (8) ; and this by dehydration to uric acid (9) : H,N COOH HN CO HN CO OC -f CH a > OC CH 2 ^ OC CH.NO, > H,N COOH HN (JO ml CO (5) (6) HN CO HN CO HN CO OC CH.NH, > OC CH.NH.CO.NH, ^ OC C.NH HN 00 HN-do HN C.NH/ (7) (8) (9) SIX MEMBERED HETEROCYCLIC RINGS 407 (2) From acetoacetic ester and urea: 4-Methyluracil is first obtained from acetoacetic ester and urea (10 below). By the action of fuming HN0 3 and H 2 S0 4 this is converted into the 5-nitro-4-carboxylic acid (11) ; this by heat to 5-nitrouracil (12) ; this by reduction to a mixture of 5-amidouracil (13), and 5-oxyuracil, or isobarbituric acid (14) ; the former of which is converted into the latter by dilute acids. By oxidation with bromine water 5-oxyuracil yields 4, 5- dioxyuracil, or isodialuric acid (15), which in presence of concen- trated H 2 S0 4 condenses with urea to uric acid (16) : HN CO HN CO HN CO HN CO OC CH ^ OC C.NO 2 > OC C.NO 2 ^ OC C.NH, ^ HN C.CH 3 HN C.COOH HN CH HN CH (10) (11) (12) (13) HN CO HN CO HN CO OC C.OH OC C.OH H 2 N V _^. OC C.NH X I II I II + / co I I! /co HN CH OC C.OH H 2 N/ HN C.NH/ (14) (15) (16) (3) From amidoacetic acid and urea, by heating glycocoll with excess of urea to 200-230: HN.CO.C.NH. 3H 2 N.CO.NH 2 +CH 2 NH 2 .COOH=: | >CO+2H 2 0+3NH 3 OC.NH.C.NH/ When pure, uric acid crystallizes in small, colorless, rhombic, rectangular or hexagonal plates, or in rectangular prisms. As crys- tallized from the urine, it is more or less colored by the urinary pig- ments, and the angles of the crystals are rounded to produce lozenge shapes, which are arranged in bundles, crosses or daggers. It is very sparingly soluble in water, requiring 36,480 parts of pure water for its solution at 18. In ordinary distilled water it is more soluble, 1: 15,000 cold, and 1 :1,900 boiling. It is soluble in 1,900 parts of a 2 per cent, solution of urea, insoluble in alcohol and ether. Cold HC1 dissolves it more readily than water, and on standing deposits it in colorless rectangular plates. Its aqueous solution is acid to litmus, but tasteless and odorless. It also dissolves unchanged in concen- trated H 2 S0 4 , and is deposited from the solution on dilution with water. It dissolves in KOH and NaOH solutions with formation of urates. Uric acid is decomposed by heat, yielding as final products ammo- nia, carbon dioxide, urea and hydrocyanic and cyanuric acids. Nas- cent hydrogen reduces it to xanthine (p. 410). With Cl, Br, or I at ordinary temperatures it forms oxalic and parabanic acids, alloxan and ammonium cyanate. Heated with Cl it yields cyanuric acid and HC1. It dissolves in cold HN0 3 , with effervescence and formation of 408 TEXT-BOOK OF CHEMISTRY alloxan, alloxantin and urea; with hot HN0 3 parabanic acid is pro- duced. A yellow or red residue remains when HN0 3 is evaporated on uric acid, and this assumes a fine red-violet or purple color when moistened, in the cold, with NH 4 OH, NaOH or KOH (murexide reac- tion). On heating with concentrated HC1 to 170 uric acid is decom- posed to glycocoll, ammonia and carbon dioxide : C 5 H 4 N 4 3 +5H 2 0=CH 2 NH 2 .COOH+3C0 2 +3NH 3 and, as ammonia and carbon dioxide are the products of hydrolysis of urea, this decomposition is the reverse of the synthesis described above (p. 406). When oxidized by lead peroxide uric acid yields allantoi'n, carbon dioxide, urea and oxalic acid, two distinct reactions occurring at the same time: HN.CO.C.NH . HN.CO.CH.NH.CO.NH 2 . 21 II > CO-f2H 2 0+0 2 =2 | +2C0 2 and OC.NH.C.NH / OC NH HN.CO.C.NH v \CO4-3H 2 O+O 2 =2H 2 N.CO.NH 2 +COOH.COOH+C0 2 . OC.NH.C.NH / Certain bacteria decompose uric acid according to the equation: C 5 H 4 N 4 3 +2H 2 0+0 3 =:3C0 2 +2H 2 N.CO.NH 2 Uric acid is decomposed by sodium hypobromite, giving off 47 per cent, of its nitrogen in the cold, or the whole when heated. It reduces the salts of copper on prolonged boiling in alkaline solution. The xanthine bases (p. 409) and uric acid are pptd. by a mixture of equal volumes of a 13 per cent, solution of CuSO and a 50:100 solu- tion of NaHS0 3 (Krliger-Wolff reagent), which does not ppt. urea. Uric acid is pptd. from solutions containing magnesia mixture, by ammoniacal AgN0 3 , as silver-magnesium urate. It is pptd., as ammo- nium urate, by complete saturation of its solutions with NH 4 C1. Uric acid behaves as a dibasic acid. The monometallic salts are formed by dissolving the acid in solutions of the metallic carbonates, or by treating solutions of the dimetallic salts with carbon dioxide. The dimetallic salts are formed by dissolving the acid in solutions of the metallic hydroxides, free from carbonate. Mono-ammonium urate, C 5 H 3 N 4 3 ( NH 4 ) , exists in the solid urines of the lower animals, and in urinary sediments and calculi. It is very sparingly soluble in water. Dipotassic urate is alkaline in taste, absorbs C0 2 from the air, and is soluble in 44 parts of cold H 2 O. Disodic urate forms nodular masses, soluble in 77 parts of cold water, and absorbs CO 2 from the air. It is probably in this form of combination that uric acid exists normally in the urine. Monosodic urate is much less soluble, requiring 1,200 parts of water for its solution. It exists, generally amorphous, in urinary sediments (amorphous urates) and calculi, and in the arthritic deposits of the gouty, sometimes beauti- fully crystalline. Monocalcic urate, soluble in 603 parts of cold water, also occurs occasionally in urinary sediments and calculi, and in " chalk stonrs." Monolithic urate, C 5 H 8 N 4 O 8 Li, crystallizes in needles, soluble in 60 parts of \\ater at 50, or in 368 parts at 19. It is chiefly with a view to the formation of this, the most soluble of the monometallic urates, that the salts of lithium SIX MEMBERED HETEROCYCLIC RINGS 409 are given to patients suffering from the uric acid diathesis. Two salts of uric acid with organic bases are still more soluble. Piperazine urate dissolves in 50 parts of water at 17 and lysidine urate in 6 parts of water. The Xanthine, Alloxuric, Purine, or Nuclein Bases form a series of which uric acid is the most highly oxidized member, and which, like uric acid, are purine derivatives: Uric acid, Xanthine, Hypoxanthine, Guanine, Adenine, C 5 H 4 N 4 3 C 5 H 4 N 4 O 2 C 5 H 4 N 4 C 5 H 5 N 5 C 5 H 5 N B Heteroxanthine, Paraxanthine, Theobromine, Theophylline, Caffeine, Epiguanine, C 5 H 8 (CH 8 )N 4 2 C 5 H 2 (CH 3 ) 2 N 4 2 C 5 H 2 (CH 3 ) 2 N 4 2 C 5 H 2 (CH 3 ) 2 N 4 2 C 8 H(CH 3 ) 3 N 4 2 C 5 H 4 (CH 3 )N 5 Of the substances named in the first column, xanthine, hypo- xanthine and guanine are, like uric acid, ketopurines, also called oxypurines, while adenine contains no oxygen; and guanine and adenine further differ from xanthine and hypoxanthine, in that they contain an amido group. Those in the second column are methyl derivatives of xanthine or of guanine, to which they bear the same relation that the methyluric acids do to uric acid. Besides the sub- stances above enumerated, carnine, C 7 H 8 N 4 3 and episarkine, C 4 H 6 3 ( ?) probably belong in this class. Adenine, guanine, hypoxanthine and xanthine are products of decomposition of nucleic acids, which are themselves products of decomposition of nucleo- proteids. The relations of the xanthine bases to each other and to uric acid are shown in the following formulae: HN CO OC C.NH HN C.NH / Uric acid. 2, 6, 8-Triketopurine. \ C HN CO OC C.NH Xantbine. 2, 6-Diketopurine. H 3 C.N CO OC C.NH ^ HN-iU// l-Methyl-2, 6- diketopurine. HN CO OC C.N Heteroxanthine. 7-Methyl 2, 6-diketo- purine. H 3 C.N CO CH 3 OC C.N II C.N \ HN Paraxanthine. 1, 7-Dimethyl- 2, 6-diketopurine. HN CO OC C.N H,C \ J J.N i CH 3 CH Theobromine. 3, 7-Dimethyl- 2, 6-diketopurine. H 3 C.N CO OC C.NH I II H 3 C.N C . N H 3 C.N CO OC C.N/ CH Theophylline. 1, 3-Dimethyl- 2, 6-diketopurine. \ H 3 C .N-H.N// CH Caffeine. 1, 3, 7-Trimethyl- 2, 6-diketopurine. HN CO I I HC C.NH II II N C.N x CH Hypoxanthine. 6-Ketopurine. HN CO .C H 2 N.C C.NH CH Guanine. 2-Amido-6-ketopurine. HN CO H 2 N. N C.N CH Epiguanine 7-Methyl-2-amido- 6-ketopurine. HC C.NH N C.N Adenine. 6-Amidopurine. 410 TEXT-BOOK OF CHEMISTRY Xanthine Xanthic Acid Urous Acid 2, 6-Diketopurine 2, 6- Dioxypurine C 5 H 4 N 4 2 occurs in a rare form of vesical calculus, in the pancreas, spleen, liver, thymus, kidneys, bijain, and in the melt of fishes. It is a normal constituent of the urine in small amount. Xanthine, hypoxanthine, guanine, and adenine are products of de- composition of the nucleins. Xanthine is obtained synthetically, either by the deamidation of guanine by nitrous acid (p. 412) ; or by Fischer's method, which, in its variations, permits of the formation of the several xanthine bases from uric acid through the chloropurines. In the formation of xanthine, uric acid is converted into 2, 6, 8-trichloropurine (1) by POC1 3 . By heating with excess of sodium ethylate this is converted into 2, 6-diethoxy-8-chloropurine (2). This is saponified by HC1 to 2, 6-diketo-8-chloropurine (3), which is then reduced by HI to xanthine (4) N-C.C1 N=C.OC 2 H 3 HN CO HN CO Cl.C C.NHv C 2 H 5 O.C C.NH V OC C.NH v OC C.NH^ (1) (2) (3) (4) Xanthine and hypoxanthine are also formed in small amount by the direct reduction of uric acid by nascent formic acid. By methyla- tion xanthine yields theobromine and caffeine. It is usually amorphous, but may form crystalline plates. It is very sparingly soluble in water, 1:14,500 at 16 degrees, 1:1,400 at 100 degrees; insoluble in alcohol or ether; readily soluble in alkalies. Its ammoniacal solution gives a gelatinous ppt. with AgN0 3 . If dis- solved in HN0 3 , and the solution evaporated, it leaves a yellow residue which, with NaOH, turns reddish-yellow, then purple-red (xanthine reaction). It gives the Weidel reaction (p. 402). As this reaction is given with uracil, cytosine, uric acid, xanthine, all the methylxanthines, and alloxan, but not by hypoxanthine, guanine, or adenine, it would seem to be characteristic of those pyrimidine com- pounds which contain the group N.CO.N, and notably of those con- taining two ketone groups, although cytosine contains but one such group. Methylxanthines. 1-Methylxanthine, 7-methylxanthine, or heteroxan- thine, and 1, 7-dimcthylxanthine, or paraxanthine occur in small quantities in the urine. With the xanthine reaction 1-methylxanthine gives an orange color; the others are negative. Theobromine, or 3, 7-dimethylxanthine, occurs in the seeds of Theobroma cacao in the proportion of about 2 per cent. It is a crystal- line powder, bitter in taste; difficultly soluble in water, alcohol, ether and chloro- form ; soluble in acids, with which it forms salts ; soluble in NH 4 OH. By partial demethylation it yields heteroxanthine. With AgN0 3 it forms a crystalline ppt., which, heated with methyl iodide, yields caffeine. Theobromine and caffeine have both been obtained synthetically by methylation of xanthine, formed by oxida- tion of guanine (p. 411). Theophylline, or 1, 3-dimethylxaiithine, occurs in Cl.C SIX MEMBERED HETEROCYCLIC RINGS 411 tea extract. It is formed from 1, 3-dimethyluric acid, and is manufactured for use as a diuretic, from uric acid. Caffeine, or theine, or guaranine, or 1, 3, 7- trimethylxanthine, exists in coffee, tea, Paraguay tea, guarana and other plants, and may be produced from 1, 3, 7-trimethyluric acid. It crystallizes in long, silky needles; faintly bitter; soluble in 75 parts of water at 15 degrees; less soluble in alcohol and ether. With HN0 3 , evaporation, and addition of NH 4 OH it gives a purple color. Hypoxanthine Sarkine 6- Ketopurine 6-Oxypurine C 5 H 4 N 4 occurs as a constituent of the nucleins in the same situations as xanthine ; also in notable amount in the blood of leukemia, and in the melt of salmon and carp ; also in numerous seeds and pollen of plants. It is a product of the decomposition of nucleins by acids, by peptic and tryptic digestion, and by putrefaction. Hypoxanthine is obtained synthetically, either by deamidation of adenine by nitrous acid (adenine, p. 412) ; or by Fischer's method from uric acid through 2, 6, 8-trichloropurine (xanthine, p. 410), (1). This is converted into 2, 8-dichloro-6-ketopurine (2) by KOH; and this is reduced by HI and PH 4 I to hypoxanthine (3) : N=C.C1 HN CO HN CO C.NH Cl.C C.NH. H.C C.NH || \C.C1 II II T // C - C1 || || >CH N " N C . N ' N C . N " (1) (2) (3) It crystallizes in small, colorless needles ; soluble in 300 parts of cold water, or in 75 parts of boiling water; soluble in acids and in alkalies. Its ammoniacal solution forms a ppt. with AgN0 3 . Fum- ing HN0 3 oxidizes it to nitroxanthine. It does not give the Weidel reaction. When acted upon by zinc and HC1, and then treated with excess of alkali, it forms a ruby-red solution, which turns brown-red (Kossel's reaction). Guanine 2-Amido-6-ketopurine occurs abundantly in guano, and as the principal constituent of the excrement of spiders; in less amount, as a constituent of guanylnucleic acid, in the spleen, liver, pancreas, in the melt of the salmon, in the scales and swimming bladders of certain fishes, in normal urine in traces, in the blood in leukemia ; and in the young leaves and pollen of certain plants. Guanine is produced synthetically in two ways: By Fischer's method, proceeding as in the synthesis of hypoxanthine (above) to the formation of 2, 8-dichloro-6-ketopurine (1). This is converted by heating with alcoholic ammonia at 150 into 2-amido-8-chloro-6- ketopurine (2) ; which is reduced by HI to guanine: HN CO HN CO HN CO Cl.C C.NH. H 2 N.C C.NH. H 2 N.C C.NH V ' (1) (2) (3) 412 TEXT-BOOK OF CHEMISTRY By Traube's synthesis, starting from cyanoacetic ester (4) and guanidine (5), which condense to cyanoacetic guanide (6). This, by union of the amide and cyanogen groups, forms an amidine, and the six-membered ring closes to 2, 4-diamido-6-oxypyrimidine (7). This, by addition of NaN0 2 to solution of the base, forms a rose-colored isonitroso compound, neither basic nor acid, which on reduction by H 2 S forms 2, 4, 5-triamido-6-oxypyrimidine (8), which is a strong diacid base, and which, on boiling with strong formic acid, forms guanine (9) : HN COO(C 2 H 8 ) HN CO N=C.OH H 2 N.c CH 2 H 2 N.i in a H 2 N.i in H 2 N CN HN CN N C.NH 2 (5) (4) (6) (7) N=C.OH HN CO HN CO H 2 N.C C.NH 2 H 2 N.C C.NH V OC C.NH . II II //CH ;>CH 1^-i.NH, N 1 t.N // HK C.N // (8) (9) (10) Guanine is deamidated by nitrous acid with formation of xanthine (10): HN.CO.C.NH v HN.CO.C.NH . I M \CH+HNO,= I \CH-f N 2 +H 2 0; H 2 N.C:N-C . N// OC.NH.C . N // and xanthine, in turn, may be methylated to theobromine and caffeine. Guanine is oxidized by KMn0 4 +HCl, with formation of guanidine and oxalylurea: HN . CO.C.NH v H 2 N CO.NH v | 1 1 >,CH+30+H 2 O= + I /) C04-C0 2 . H 2 N.C:N C.N // H 2 N.C:NH CO.NH 7/ Guanine is a white or yellowish, amorphous and odorless powder : almost insoluble in water, alcohol and ether; readily soluble in acids and alkalies. It forms crystalline ppts. with silver nitrate and with picric acid. It gives the xanthine reaction with HN0 3 and NaOH; but it does not respond to the Weidel reaction. Adenine 6-Amidopurine C 5 H,N 5 exists, in nucleic acids, widely disseminated in nucleated cells, most abundantly in carp-melt and in the thymus gland. It occurs in the blood and urine in leukemia, and also exists in yeast and abundantly in tea leaves. It is formed synthetically by Fischer's method: By the action of POC1 3 upon potassium urate 2, 6-dichloro-8-ketopurine (1) is pro- duced. This is converted into 2-chloro-6-amido-8-ketopurine (2) by SIX MEMBERED HETEROCYCLIC RINGS 413 NH 3 . This is converted by POC1 3 into 2, 8-dichloro-6-amidopurine (3) ; which is reduced by HI to adenine (4) : N=C.NH 2 Cl.C C.NH X Cl.C C.NH X Cl.C C.NH X HC C.NH v )CO || || >CO || || \CC1 |J || /)CH N C.NH / N C.NH ' N C . N 7/ N C . N " (1) (2) (3) (4) As guanine is deamidated to xanthine, so adenine, on deamidation, yields hypoxanthine : N : C ( NH 2 ) .C.NH x HN.CO.C.NH x I M /)CH+HN0 2 = I || /)CH+N 2 -fH 2 0. CH:N -- C.N" CHrN.C.N// Adenine crystallizes in nacreous plates, or in long needles, with 3 Aq, which they lose at 100 , although they suddenly become opaque at 53, a property characteristic of adenine. Very soluble in hot water, it requires 1,086 parts of cold water for its solution ; insoluble in cold alcohol, ether and chloroform; readily soluble in acids and alkalies, with which it forms compounds. Its solubility in ammonia is less than that of hypoxanthine, but greater than that of guanine. It forms crystalline, difficultly soluble compounds with silver nitrate and with picric acid. It is not reddened by warming with HN0 3i and moistening the residue with alkali; does not respond to the Weidel reaction, but behaves like hypoxanthine towards Kossel's reaction. Carnine C 7 H 8 N 4 O 3 is obtained from Liebig's meat extract, and has also been found in the muscular tissues of fishes and frogs, and in the urine. It is isomeric with the dimethyluric acids. It forms chalky, microscopic crystals, readily soluble in hot water, sparingly soluble in cold water, insoluble in alcohol and ether. It forms compounds with acids and with alkalies, similar to those of hypoxanthine. Chlorine, bromine and nitrous acid convert it into hypoxanthine, with elimination of the elements of acetic acid. It does nofc respond to the Weidel reaction. Epiguanine C 6 H 7 N 5 O 3 . Besides 7-methylxanthine, which is heteroxanthine, and 7-methyluric acid, similar derivatives of hypoxanthine, guanine and adenine have also been obtained synthetically. 7-Methyl-guanine is epiguanine, which occurs in minute quantity in the urine. Episarkine is possibly identical with epiguanine. Triazines are compounds containing three nitrogen atoms in a six-membered ring: H C N=CH N=CH N=CH |] II or N CH N CH HC N or N 1, 2, 3-Triazino. 1, 2, 4-Triazlne. 1, 3, 5-Triazine. Orthotriazine. Metatriazlne. Paratrlazine. Cyanidine. 414 TEXT-BOOK OF CHEMISTRY The parent ortho- and meta-compounds are not known, but many of their derivatives have been obtained, none of which is, however, of medical interest. Para-, or /-triazine, also called cyanidine, is the still unidentified trihydrocyanic acid, which is the parent substance of certain metal- locyanides, and of the cyanuric compounds (p. 307). B. CONDENSED HETEROCYCLIC COMPOUNDS. These compounds, which are more numerous than the correspond- ing carbocyclic compounds, may be considered as being derived from the latter by substitution of N for methine, =CH , or of 0, S, or NH in a bivalent position, or, as in the case of iso-indole (below), by substitution and modification of internal linkage. The number of these substances is still further increased by the existence of four ringed-compounds, such as the anthraquinolines and indigo-blue (p. 417). The formulae below are those of some of the nitrogen derivatives, in which indole and isoindole may be considered as de- rived from indene (p. 385) : carbazole from fluorene; quinoline, iso- quinoline and naphthydrine from naphthalene: acridine and the anthrapyridines from anthracene; and phenanthridine from phen- anthrene : H C //4\ HC3 C CH/3 HC2 C CHa \\1/ \ / C Nn H H Benzo-pyrrole. (Indole). H H C C7 //4\ / \\ HC3 C CH/3 HC2 C CHa \\1/ \ // C N H Benzo-pyridine. (Quinoline) H H H C C C II ^ / \ / \\ HC "c C H( l I! fl \\ / ' \ / \ // C N C H H Acridine. H H C C // \ / \\ HC C C CH Hrf"1 C* ^"ITT \J \J \J V^il \\ / \ / \ // C N C H H H Diphenylone-imide. (Carbazole). H C \ \\ HC C CH HC C CH \\ \ N N CH HC H ] C ( // \ / C II a ^ \ / c H H C ' \\ c \\ / \ C ( H 1 (J / \ j BE ^C H a-. \iithnipyrldine. Naphthydrine. CH CONDENSED NUCLEI CONTAINING A NITROGEN MEMBER 415 H H H H H H H C. C C C=C C=C //\/\/\\ / \ / \ HC C C CH HC C C CH II N I \\ // \\ // C C CH C C C C \\ / \\/ \ // H \ / H C C N N=C H H H /3-Anthrapyridine. Phenanthridine. CONDENSED NUCLEI CONTAINING A NITROGEN MEMBER. BENZOPYRROLE AND ITS DERIVATIVES INDIGO COMPOUNDS Indole Benzopyrrole (formula p. 414) is produced: (1) by distilling oxindole oxer zinc-dust; (2) by heating o-nitric cinnamic acid with potash and iron filings, or by similar reduction of other unsaturated o-nitro substitution products of benzene (3) by the interaction of calcium formate and phenylglycocoll (p. 375). It is one of the products of putrefaction of the proteins by anerobic bacteria, and is formed in the intestine during pancreatic digestion of those substances. It is partly eliminated with the feces and partly reabsorbed, appearing in the urine in sulphocon jugate com- bination. It crystallizes in large, shining, colorless plates, having the disagreeable odor of naphthylamine. It is a weak base, and its salts are decomposed by boiling water. Its aqueous solution, acidu- lated with HC1, is colored rose-red by KN0 2 . By fusion with KOH it yields aniline. It gives the " pine-shaving reaction " (p. 416). It forms a compound, crystallizing in red needles, with picric acid. Indole Homologues Derivatives of indole are produced by sub- stitution either in the benzene or in the pyrrole ring. The positions are distinguished as Bz. 1, 2, 3, 4 and Py.n, a, and /? (see formula p. 414). The alkyl indoles, the superior homologues of indole, are formed: (1) by heating aniline with compounds containing the group CO.CH 2 C1. Thus chloracetone and aniline yield tf-methylindole : CH 2 C1.CO.CH 3 +C 6 H 5 .NH 2 =C 6 H 4 ( X )C.CH 3 +HC1+H 2 ; (2) By heating the phenylhydrazones of the ketones, aldehydes or ketone acids with ZnCl 2 . Thus n, <*-dimethylindole is obtained from acetone-phenyl-methyl-hydrazone: The best known alkyl indoles are those in which the alkyl group is in the pyrrole ring. They dissolve in concentrated acids, and are precipitated unaltered from the solutions by dilution with water. Fused with KOH, they yield potassium salts of indole-carboxylic acids. Their hydrogen may be replaced by acidyls or by the diazo 416 TEXT-BOOK OF CHEMISTRY group. They give the "pine-shaving reaction," and form red, crystalline compounds with picric acid. Indole-/2-acetic acid. The product of putrefaction, which also exists in normal urine, described as skatole carboxylic acid, is not that substance, but its isomere, indole- /^-acetic acid (formula below). It produces an intense violet color with HC1 and dilute FeCl 3 solution. Tryptophane Proteinochromogen /?./?.-Indole-<*.-amidopropionic Acid CH 2 ! .CH 2 .COOH HC C C CH.NH 2 COOH is a product of decomposition of proteins by energetic decomposing agents such as Ba(OH) 2 ,H 2 S0 4 , tryptic digestion and putrefaction, but not by peptic digestion. With Br or Cl it forms a red-violet pig- ment, called proteinochrome. It crystallizes in shining plates, easily soluble in hot water, difficultly, in cold water or alcohol. When heated it yields indole and skatole. It gives the Adamkiewicz reaction. Its solution on a pine shaving, previously moistened with HC1, and sub- sequently washed and dried, gives a purple color (pyrrole reaction). By anerobic putrefaction it yields indole- yfl-propionic acid; and by aerobic putrefaction indole- y#-acetic acid, and indole. ^-Methyl-indole Skatole C C H 4 (^ H3) ^CH exists in feces, in which it exceeds the indole in amount. It is formed during putre- faction of the proteins, or by the action upon them of KOH in fusion; also by the reduction of indigo. It is best obtained syntheti- cally by heating propidene-phenylhydrazone with zine chloride: It crystallizes in brilliant plates; f. p. 95; insoluble in water, soluble in alcohol and in ether; distils with vapor of water; has a strong fecal odor. Its solution in concentrated HC1 is violet. Its H 2 S0 4 solution is colored deep purple when heated. Skatole, like indole, is in part reabsorbed from the intestine, and appears in the urine, combined with sulphuric and glucuronic acids. Iso-indole (formula, p. 414) is formed by the action of alco- holic ammonia upon brom-acetophenone. It crystallizes in colorlrss, silky plates; f. p. 195; insoluble in water, soluble in alcohol, ether and benzene. Indoxyl ^.Oxyindole C 6 H 4 H3CH not to be con- CONDENSED NUCLEI CONTAINING A NITROGEN MEMBER 417 founded with oxindole (below), is a phenolic derivative of indole, obtained from indigo-blue by fusion with KOH without contact of air; or from its a-carboxylic acid, indoxylic acid. It is a very unstable, oily substance, soluble in water, and readily oxidized to indigo-blue (below). It readily combines with sulphuric acid or the sulphates to form indoxyl-sulphuric acid, the potassium salt of which is uroxanthine, or urinary indican. This latter is formed from indole, and its relations are shown by the following formula: CH 3 O vx /OH I S CH 2 .OH O// X O.CH 2 .CH 3 Ethyl-alcohol. Ethyl-sulphuric acid. O /OH \\g/ O// X O.C 6 H S Phenyl-sulphuric acid. OH \\ / S NH // \ / \ O O.C=:CH C 6 H 4 Indoxyl-sulphuric acid. Acids decompose it, with formation of indoxyl, which is converted into indigo-blue by FeCl 3 . Oxindole C 6 H 4 <^ N 2 /CO the lactam of o-amido-phenyl acetic acid, is obtained from dioxindole by reduction with sodium amalgam in acid solution; or by reduction of o-nitrophenyl-acetic acid. It crystallizes in easily soluble, colorless needles; f. p. 120. In moist air it oxidizes to dioxindole. It reduces ammoniacal silver nitrate solution. It combines with acids and bases. Isatine C 6 H 4 <^ NH /CO the lactam of o-amido-benzoyl-formic acid, is formed by oxidation of indigo-blue by HN0 3 ; by oxidation of oxindole ; and by other methods. It crystallizes in shining, trans- parent, red-brown prisms, odorless, sparingly soluble in water, readily soluble in alcohol. Indigo-blue IndigotineC 6 H 4 ^g V ),C:C^^>C 6 H 4 constitutes the greater part of commercial indigo. It does not exist preformed in nature, but many plants, particularly Indigotifera tinctoria and I satis tinctoria, contain a yellow glucoside, indican (p. 363), which on heating with dilute acids, or probably by enzymic action on ex- posure to air in presence of water, is decomposed into a sugar and indigo-blue. Commercial indigo contains 20 to 90 per cent, of 418 TEXT-BOOK OF CHEMISTRY indigo-blue, which may be separated, nearly pure, by cautious sub- limation. It is formed in several reactions, e.g., by oxidation of indoxyl by FeCl 3 and HC1 ; from o-nitro-cinnamic acid by two methods; by fusing phenyl-glycocoll with KOH ; or by heating o-nitro-acetophenone with zinc dust. It forms purple-red, metallic shining prisms or plates, odorless, tasteless, neutral, soluble in hot aniline, hot oil of turpentine, and melted paraffin, insoluble in the usual solvents. When heated it is in part converted into a dark-red vapor, and partly decomposed into aniline and other products. In the presence of aqueous alkaline solutions, reducing agents convert indigo-blue into indigo- white, or di-indoxyl,C 6 H 4 y N jj^JJ^C C- ^-LNH/ C 6 H 4 , which dissolves in the alkali. This substance absorbs oxygen from the air rapidly, with regeneration of indigo-blue. In absence of air it may be precipitated from its alkaline solution by HC1, as a white, crystalline powder, insoluble in water, but soluble in alcohol and ether, forming yellow solutions. When oxidized, as by warming with dilute HN0 3 , indigo-blue is converted into isatine, whose dilute solutions are also yellow. Hence the decoloration of indigo-blue solution is utilized as a test both for oxidizing (HN0 3 ) and for reducing (Mulder-Neubauer test for glucose) substances. QUINOLINE AND ISO-QUINQLINE AND THEIR DERIVATIVES. The quinoline, or benzo-pyridine bases accompany the pyridine bases in bone-oil, and like those substances, are closely related to the vegetable alkaloids. Quinoline, the parent substance of the group, was first obtained by distilling quinine and cinchonine with lime. Chemically the quinolines are also related to the naphthalenes, and are formed by similar synthetic methods. Thus quinoline is formed from allyl-aniline : C 6 H 5 .NH.CH 2 .CH :CH 2 =C 6 H 4CH: ' CH +2H 2 , in the same manner as naphthalene is formed from phenyl- butylene. Quinoline and its derivatives may also be produced syn- thetically: (1) From o-amido-benzenic compounds containing an oxygen atom in the second lateral chain. Thus o-amido-benzoic alde- hyde and acetone yield tf-methyl-quinoline : / CHlCH +2H 2 0. (2) By heating the anilines with glycerol and H 2 S0 4 , in presence of an oxidizing agent, such as nitro-benzene : /CH:CH C 6 H 5 .NH 2 +CH 2 OH.CHOH.CH 2 OH=C 6 H 4 I +3H 2 0+H 2 ALKALOIDS 419 (3) By the action of aldehydes upon anilines in presence of H 2 S0 4 or HC1. Thus <*-methyl-quinoline is obtained from aniline and acetic aldehyde : /CH:CH C 6 H 5 .NH 2 +2CHO.CH 3 =C 6 H 4 | +2H 2 0+H 2 \N :C(CH 3 ) The quinoline bases are liquids of penetrating odor, sparingly sol- uble in water, readily soluble in alcohol and in ether. They are strong triacid bases, and form salts and ammonium-like compounds. /CH:CH Quinoline C 6 H 4 I is a mobile liquid; b. p. 238, becom- \N : CH ing rapidly brown on exposure to air; has an intensely acrid and bitter taste, and an odor somewhat like that of bitter almonds; sparingly soluble in water, readily soluble in alcohol and ether. Its dichromate crystallizes in yellow needles; f. p. 165; very sparingly soluble in water. Quinoline is of medical interest chiefly in connection with the vegetable alkaloids of which it is the nucleus (p. 428). Certain syn- thetic basic substances containing the quinoline nucleus have also been used in medicine, in saline combination, as antiperiodics and antipyretics. yCH.CH Iso-quinoline C 6 H 4 / | differs from quinoline in that the attachment of the benzene and the pyridine rings is by the ft and y positions of the latter in iso-quinoline, and by the a and ft positions in quinoline (see formulae, p. 414). It accompanies quinoline in coal- tar, and is the nucleus of some of the opium alkaloids (p. 437). It resembles quinoline in its properties. F. p. 23; b. p. 240.5. ALKALOIDS. Until the constitution of all the substances grouped under this term shall have been determined, the limitations of the application of the name can be only provisional. It was first applied to the few alkali-like substances first obtained from vegetable products, the vegetable bases morphine, narcotine, veratrine, strychnine. After- wards its application was extended, and at the same time made more precise, to include organic, nitrogenized substances, alkaline in re- action, and capable of combining with acids to form salts in the same way as does ammonia. This limitation, is, however, too broad, as it classes the aliphatic amines, and other similar bodies, with the true alkaloids, which are cyclic. All substances generally classed as alka- loids, whose constitution has been determined, contain at least one nitrogen-containing heterocyclic ring, except theobromine and caf- feine, which are not true alkaloids, but purine bases (p. 409). Almost all alkaloids of known constitution contain the pyridine ring, more 420 TEXT-BOOK OF CHEMISTRY or less modified by hydrogcnation, either alone or in quinoline or isoquinoline. Therefore, until recently, alkaloids were considered to be : basic substances containing the pyridine ring. But the hygrines, alkaloids existing in coca leaves, are derivatives, not of pyridine, but of pyrrolidine, a five-membered nucleus. So far as is now known, no alkaloid contains more than one nitrogen atom in one and the same ring. Therefore, provisionally, it may be stated that the alka- loids are basic substances derived from heterocyclic nuclei containing but one nitrogen atom in any nucleus. Under this definition pyri- dine and quinoline and their homologues are alkaloids, as well as indole, and other basic pyrrole compounds. Properties. Some of the alkaloids, nicotine, coniine, sparte'ine and arecoline are liquid, volatile, and contain C, N and H. Most of them, to the number of more than a hundred, are solid, crystalline, only partially volatile without decomposition, if at all, and contain C, N, H and 0. Most of the alkaloids are very sparingly soluble in water, although some are readily soluble; but soluble in alcohol, ether, petroleum-ether, chloroform, benzene or amylic alcohol. Their salts, on the other hand, are, for the most part, soluble in water, but insoluble in the other solvents mentioned, except alcohol, in which they are soluble. They are laevogyrous, except quinidine, chincho- nine, coniine, narcotine, and pilocarpine, which are dextrogyrous. Usually their rotary power is diminished by combination with acids, although with quinine the reverse is the case. Free narcotine is laevogyrous, its salts are dextrogyrous. Most of the alkaloids are bitter in taste, and alkaline in reaction. The naming of the salts of the alkaloids has been the subject of no little discussion. The names of the alkaloids are made to terminate in ine. As most of the alkaloids are tertiary amines and some secondary amines, they combine with acids in the same manner that ammonia does, that is, without elimination of water or of hydrogen, and by change of the nitrogen valence from trivalent to quinquivalent: 2H,: + H 2 S0 4 = ( H a. : N:) a ((f5 4 Ammonfa. Sulphuric acid. Ammonium sulphate. 2 [ ( C 1T H 1U 8 ) :N ] + H 2 S0 4 = [ ( C lf H^O. ) ;N : j 2 Morphta. Sulphuric acid. Morphi'tm sulphate. Therefore these salts do not contain morphine, C M H u OaN'", as a substitute for the hydrogen of the acid, but the hypothetical morphium ( C a7 H 20 3 N T ) ', as the ammoniacal salts are not salts of ammonia, NH 3 , but of ammonium, NH 4 . The compounds formed by the union of morphine and other alkaloids with the hydracids, HC1, HBr, HI, may properly and conveniently be referred to as morphine hydrochloride (not hydrochlorate ) hydrobromide, hydroiodide, etc., they being considered, not as salts of those acids, but as compounds in which one of the valences of the quinquivalent nitrogen atom is satisfied by hydrogen and another by chlorine. ALKALOIDS 421 Many of the alkaloids behave like esters, and are hydrolyzed by baryta or the caustic alkalies, or by mineral acids, into two com- ponents, one a base, the other an acid, the latter usually cyclic and nitrogenous. On the other hand, concentrated HC1 removes H 2 from those alkaloids containing more than one hydroxyl, converting them into apo-alkaloids, as morphine is converted into apomorphine. Other alkaloids, containing methoxyl groups (OCH 3 ) ? when acted upon by concentrated HC1, are modified by replacement of OH for the methoxyl groups. Reducing agents with alkaloids whose nuclei contain double bonds, form hydro-bases, as piperidine is derived from pyridine. Distillation with zinc-dust causes removal of the lateral chains from the oxygen-containing alkaloids, with liberation of pyri- drine or quinoline. Oxidizing agents form carboxylic acids, or de- compose the alkaloid into an acid and a base, or cause the union of two molecules of the alkaloid with loss of hydrogen. General Reactions of the Alkaloids. A great number of "gen- eral reagents" for alkaloids have been suggested, of which only the more important can be here mentioned: Potash, soda, ammonia, lime, baryta and magnesia precipitate the alkaloids from solutions of their salts. Phospliomolybdic acid forms a precipitate which is bright-yellow with aniline, morphine, veratrine, aconitine, emetine, atropine, hyos- cyamine, theme, theobromine, conime, and nicotine; brownish-yellow with narcotine, codeine, and piperine; yellowish-white with quinine, cinchonine, and strychnine; yolk-yellow with brucine (DeVry's, or Sonnenschein 's reagent) . Potassium iodhydrargyrate gives a yellowish precipitate with alkaloidal solutions which are acid, neutral or faintly alkaline in reaction (Mayer's reagent). Classification of the Alkaloids. The alkaloids of known, or par- tially known constitution, can be classified according to the nuclei which they contain: A. Pyrrolidine- Alkaloids. Tho hygrines. B. Pyridine- Alkaloids. Trigonelline, pilocarpine (?). C. Piperide'ine (tetrahydropyridine) Alkaloids. Arecoline, are- caidine x-conicei'ne (?), pseudopelletierine, pelletierine (?). D. Piperidine Alkaloids. Conime, conhydrine, arecaine, juva- cine, piperine. E. Pyrrolidine-pyridine AZ&aZowZs. Nicotine. F. Pyrrolidine-piperidine Alkaloids. Tropan Alkaloids. Atro- pine, hyoscyamine, hyoscine (?), ecgonine, cocaine, cinnamyl-cocaine, tf-truxilline, y^-truxilline, benzoyl-ecgonine, tropacocai'ne. G. Quinoline Alkaloids. Cinchona alkaloids, strychnos alka- loids (?). H. Isoquinoline Alkaloids. Papaverine, narcotine, narceine (0, hydrastine, berberine (?). 422 TEXT-BOOK OF CHEMISTRY I. PJienanthrene Alkaloids. Morphine, codeine, thebai'ne. X. Alkaloids of unknown constitution. Piperidine Alkaloids. The alkaloids known to contain a single piperidine ring as a nucleus are the five alkaloids of Conium macu- latum, coniine,C 8 H 17 N, conhydrine, C 8 H 17 NO, coniceine, C 8 H ir ,X, tt-methyl-coniine, C 9 H 19 N, and pseudoconhydrine, C 8 H 17 NO; and two of the four betel-nut alkaloids: arecaine, C 7 H 11 N0 2 , and guva- cine, C 6 H 9 N0 2 . Coniine C 8 H 17 N is one of the most simply constituted of the natural vegetable alkaloids, and was the first to be produced synthet- ically. It is a colorless, oily liquid; has an acrid taste and a dis- agreeable, penetrating odor ; sp. gr. 0.844 ; can be distilled when pro- tected from air ; b. p. 166 . Exposed to air it resinifies. The natural alkaloid is d-conime, [#] D=15.7. It is very sparingly soluble in water, but is more soluble in cold than in hot water; soluble in all proportions in alcohol, easily soluble in ether, and in fixed and volatile oils. Its vapor at ordinary temperatures forms a white cloud when in contact with a glass rod moistened with HC1, as does NH 3 . It forms salts which crystallize with difficulty. Chlorine and bromine combine with it to form crystallizable compounds ; iodine in alcoholic solution forms a brown precipitate in alcoholic solutions of coniine, which is soluble without color in an excess. Ethyl and methyl iodides combine with it to form crystallizable compounds; iodine in alcoholic solution forms a brown precipitate in alcoholic solutions of conime, which is soluble without color in an excess. Ethyl and methyl iodides combine with it to form ethyl- and methyl-coniine hydriodides. It has been obtained synthetically from a-picoline by reactions which show it to be <*-propyl piperidine. The relations of pyridine, piperidine, and conime are shown by the following formulae : H H, H 2 C C C /\\ /\ /\ HC CH H 2 C CH 2 H 2 C CH 2 HC CH H 2 C CH 2 H 2 C CHC 8 H T \// \/ \/ N N N H H Pyridine. Piperidine. Coniine. ANALYTICAL CHARACTERS .(1) With dry HC1 gas it turns red- dish-purple, 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 H 2 SO 4 and evaporation of the acid: a red color, changing to green, and an odor of butyric acid. (5) When mixed with commercial nitrobenzene a fine blue color is produced, changing to red and yellow. ALKALOIDS 423 Paraconiine C 8 H 15 N is a synthetical product closely resembling coni'ine, Obtained by first allowing butyric aldehyde and an alcoholic solution of ammonia to remain some months in contact at 30, when dibutyraldine is formed: 2(C 4 H 8 0)+NH 8 =C 8 H 17 NO+H 2 0. The dibutyraldine thus obtained is then heated under pressure to 150- 180 , when it loses water, and forms paraconiine : C 8 H 17 NO= C 8 H 15 N-|-H 2 0. A synthesis which, in connection with the decom- positions of paraconiine, shows its rational formula to be * 4 H 7 yN. Pipeline C 17 H 19 N0 3 isomeric with morphine, and occurring in black and white pepper, crystallizes in large prisms; f. p. 128; almost insoluble in water, readily soluble in alcohol and in ether. It is a weak base, without alkaline reaction, and only forming very un- stable salts with concentrated acids. It is one of the alkaloids whose complete synthesis has been accomplished, and is quite directly de- rived from piperidine, of which it is an n-acidyl derivative. When piperine is heated with alcoholic soda, it is hydrolyzed into piperic acid, C 12 H 10 4 , and piperidine. It is therefore piperidine piperate, or piperidine-3, 4-methylene-dioxy-cinnamyl-acrylate : H H 2 H 2 C C C C O x /\\ /\ /\ /\\ >CH 2 HC CH H 2 C CH 2 H 2 C CH 2 HC C / HC CH H 2 C CH 2 H 2 C CH 2 HC CH \// \/ \/ \// N N N C H CO . CH : CH . CH : CH Pyridine. Piperidine. Tiperine. Pyrrolidine-pyridine Alkaloids are represented by Nicotine C 10 H 14 N 2 which exists in tobacco in the proportion of 2-8 per cent. It is a colorless, oily liquid, which turns brown on exposure to air, has a burning, caustic taste, and a disagreeable, penetrating odor. It distils at 250; burns with a luminous flame; sp. gr. 1.027 at 15; is very soluble in water, alcohol, the fatty oils, and ether. The last-named fluid removes it from its aqueous solu- tion when the two are shaken together. It absorbs water rapidly from moist air. Its salts are deliquescent, and crystallize with diffi- culty. The natural alkaloid is 1-nicotine. The i-nicotine has been obtained by total synthesis, through /5-amidopyridine. From this 1-nicotine is produced by the action of tartaric acid. The oxidation of nicotine produces nicotinic, or (3 monocarbo- pyridic, acid. When distilled with zinc chloride and lime it yields pyrrole, ammonia, methylamine, hydrogen, and pyridine bases. When heated to 250 it yields a collidine along with other products. By limited oxidation it produces a substance, C 10 H 10 N 2 , formerly con- 424 TEXT-BOOK OF CHEMISTRY sidered as isodipyridine, but shown to be /?-pyridine-n-methyl-a- pyrrole, (~I-TT /^TT r^TT PTI . U-tl V^Xl . // V^Xl HC< >C C(' || NX N -CH// X N(CH 3 )CH of which nicotine is the tetrahydro, or pyrrolidine derivative f!H=CIL , CH 2 CH 2 \C CH/ CH 2 ANALYTICAL CHARACTERS. (1) Its ethereal solution, added to an ethereal solution of iodine, separates a reddish-brown, resinoid oil, which gradually becomes crystalline. (2) With HC1, a violet color. (3) With HN0 3 , an orange color. TOXICOLOGY. Nicotine is a very active poison. The free alkaloid is prob- ably capable of causing death in doses of two to three drops. It was the first alkaloid to be separated from the cadaver in a case of homicide. Most cases of poisoning from nicotine are due to tobacco, frequently resulting from its use in enemata. When administered to dogs in doses of two to four drops, its effects begin within half a minute to two minutes, and death ensues within one to five minutes. In man tobacco or its decoction causes nausea, vertigo, dilatation of the pupils, vomiting, syncope, diminution of the rapidity and force of the heart. With large doses there are no subjective symptoms, the victim falls unconscious instantly, and dies within five minutes, without con- vulsions, and with very few or only one deep sighing respiratory act. The 1-nicotine has double the toxic power of d-nicotine, and the two forms differ in the nature of the action produced. Pyrrolidine-piperidine Alkaloids Tropan Alkaloids. The alka- loids of this group, most of which are ester-alkaloids, including the atropic alkaloids, atropine, hyoscyamine, and hyoscine, and the coca alkaloids, ecgonine, cocaine, cinnamyl-cocame, a- and ^-truxillines, benzoylecgonine and tropacocai'ne, are derivatives of tropan (1), the ri-methyl derivative of nortropan (2), both of which are known, as well as many of their compounds other than alkaloids : H, C \ H 2 C CH CH, H 2 C HC CH 2 HN or CH 2 | C CH, I \ / H,C CH CH, H,0 C H 2 C C H (2) Nortropan may be considered as formed by condensation of a pyrrolidine ring and a piperidine ring, having the group =CII.NH.- ('11= in common. The following tropan derivatives are of interest in connection with the syntheses of atropic and coca alkaloids. ALKALOIDS 425 Tropidine (formula below) is a dehydrotropan, first obtained as a product of decomposition of atropine, and later of cocaine, thus indicating the relationship of the two alkaloids. It has been obtained by total synthesis, starting from synthetic glycerol (p. 223), through allyl bromide, trimethylene bromide, trimethylene cyanide, glutaric acid (p. 259), to suberone (formula below). From suberone to tro- pidine many steps are required, the principal intermediate products being cycloheptene (2), cycloheptatriene, and ^-methyltropidine : H 2 C.CH 2 .CO H 2 C.CH 2 .CH H 2 C.CH CH iGH 2 CH N.CH 3 CH .CH 2 .CH 2 H 2 C.CH 2 .CH 2 H 2 C.CH CH 3 Suberone. Cycloheptene. Tropidine. Tropine (formula p. 426) 4-Tropan Alcohol is formed through its space isomere, ^-tropine, by conversion of tropidine into a dibromo addition product, and splitting off of Bf 2 and addition of H 2 by heating with H 2 S0 4 at 200. Tropine is the alcoholic com- ponent of atropine, hyoscyamine and the tropeines, and of which ecgonine (p. 427) is the carboxylic acid. Atropine i-Tropine tropate C 17 H 23 N0 3 . Belladonna, stramo- nium, hyosyamus and duboisia contain five alkaloids: atropine, hyoscyamine, hyoscine, scopolamine and belladonnine, of which the first two are optical isomeres of each other. Atropine forms colorless, silky needles, sparingly soluble in cold water, more readily in hot water, very soluble in chloroform. It is odorless, has a disagreeable, persistent, bitter taste. Both tropine and tropic acid (see below) contain an asymmetric carbon atom. The tropine in atropine is i-tropine, and the acid is d-tropic acid. Both natural and synthetic atropines are optically inactive. Atropine is distinctly alkaline, and neutralizes acids with formation of salts. The sulphate is a white, crystalline powder, readily soluble in water. Atropine is the type of the "ester alkaloids" saponifiable into an acid and an alcoholic component. When it is acted upon by Ba(OH) 2 at 60, or by NaOH or HC1 at 120-130, it is saponified, after the manner of an ester, into tropic, or a-phenylhydracrylic acid, C 6 H 5 .CH \CHOH ' anc ^ a secon dary cyclic alcohol, tropine (formula below). But if the action be prolonged the tropic acid is further decomposed into or-phenylacrylic, or atropic, and isatropic acids. And if, during the action of HC1, the temperature rises to 180, the tropine loses water, and is converted into tropidine. The relation of atropine to its progenitors is shown in the fol- lowing formulae: 426 TEXT-BOOK OF CHEMISTRY H 2 C.CH CH 2 iN.CH 3 CH 2 .CH CH 2 Tropan. H 2 C.CH CH H 2 C.CH CH 2 N.CHs CH N.CH 3 CHOH H 2 C.CH CH 2 H 2 C.CH CH 3 Tropidine. Tropine. H H 2 C.CH CH 2 C N.CHs I //\ CH.OOC.CH C CH H 2 C.CH -CH 2 CH 2 OH HC CH \\/ C H Tropine tropate Atropine. HOOC.CH C CH CH 2 OH HC CH V H Tropic Acid. ANALYTICAL CHARACTERS. (1) If a fragment of potassium di- chromate is dissolved in a few drops of H 2 S0 4 , the mixture warmed, a fragment of atropine and a drop or two of H 2 added, and the mix- ture stirred, an odor of orange-blossoms is developed. (2) A solu- tion of atropine dropped upon the eye of a cat produces dilatation of the pupil. (3) The dry alkaloid (or salt) is moistened with fum- ing HN0 3 and the mixture dried on the water-bath. When cold, it is moistened with an alcoholic solution of KOH ; a violet color, which changes to red (Vitali). (4) If a saturated solution of Br in HBr is added to a solution of atropine, a yellow precipitate is formed, which rapidly becomes crystalline, and which is insoluble in acetic acid, sparingly soluble in H 2 S0 4 and HC1. TOXICOLOGY. The clinical history of atropic poisoning is divisible into two stages, the first one of delirium, in which the prominent symptoms are dryness of the throat, thirst, difficulty of deglutition and spasms upon swallowing liquids, face at first pale, afterwards highly reddened, pulse extremely rapid, eyes prominent, brilliant, with widely-dilated pupils, complete paralysis of accommodation, disturbances of vision, attacks of giddiness and vertigo, with severe headache, followed by delirium, occasionally silent or muttering, but usually violent, noisy and destructive, accompanied by the most fantastic de- lusions and hallucinations. Usually the urine is retained, and the body tem- perature is above the normal. The delirium gradually subsides, and the second stage, that of coma, is established, with slow, stertorous respiration, and grad- ually failing pulse, until death occurs from respiratory or cardiac paralysis, or sometimes in an attack of syncope during apparent amelioration. In some cases, the patient rapidly becomes comatose at the outset, and the symptoms of the first stage are manifested as the coma diminishes. The treatment should consist of lavage of the stomach, and morphine may be given cautiously during the period of violent excitement. In the second stage, the treatment is the same as in morphine poisoning. Pilocarpine may be given, in not too large doses, to stimulate the secretion of saliva. Atropic poisoning leaves no characteristic post-mortem lesions. Hyoscyamine C 17 H 23 N0 3 isomeric with atropine, predominates in Hyoscyamus niger, and in m&ndragora. It differs from atropine ALKALOIDS 427 principally in being laevogyrous, [>] D = 20.3, and on saponifica- tion it yields 1-tropic acid and i-tropine. It is converted into atropine very easily, by heat, or by addition of alkali to its alcoholic solution. Apoatropine Atropamine Tropine atropate C 17 H 21 N0 2 is formed by the action of dehydrating agents, H 2 S0 4 , P 2 5 , etc., on atropine or hyoscyamine, by splitting off of H 2 from the acid com- ponent, thus converting the residue of the saturated tropic acid into that of the unsaturated atropic acid. By heat it is converted into its isomere, belladonnine, an alkaloid which accompanies atropine in belladonna. Hyoscine and scopolamine, C 17 H 21 4 , are two iso- meric, mydriatic alkaloids, accompanying atropine in belladonna. The latter on decomposition yields tropic acid and scopoline, C 8 H 13 - N0 2 , which is closely related to tropine, C 8 H 15 NO. Tropei'nes are ester-like derivatives of tropine with acids, similar to atropine. Many such have been formed with organic acids, ben- zoic, salicylic, etc. That formed with mandelic acid is known as homatropine, C 8 H 14 N.OOC.CH(OH).C 6 H 5 , is used as a mydriatic having a less prolonged action than atropine. Only those tropeines whose acid radicals contain an alcoholic hydroxyl have a mydriatic action. Ecgonine C 9 H 15 N0 3 an alkaloid existing in Eryfhroxylon coca, and the parent substance of cocaine and other coca alkaloids, is 4- oxytropan-5-monocarboxylic acid (p. 428). By the action of dehy- drating agents upon ecgonine the alcoholic OH and an H atom are split off, and anhydroecgonine, C 9 H 13 N0 2 , is formed, which, by split- ting off of C0 2 from the carboxyl, forms tropidine. Ecgonine, being both basic and acid, forms esters and salts, and numerous products of derivation other than cocaine. When acted upon by a mixture of methyl iodide and benzoic anhydride, ecgonine is converted into cocaine. Or by substitution of other alkyl iodides for that of methyl, other alkaloids, homologous with cocaine, are obtained (see formulae below) . Cocaine C 17 H 21 N0 4 the most important of the coca alkaloids, is closely related chemically to atropine. It crystallizes in large four- or six-sided prisms; f. p. 98; sparingly soluble in water, readily soluble in alcohol, ether and chloroform ; somewhat bitter at first, but causing paralysis of the sense of taste afterwards; strongly alkaline. Its hydrochloride, used as a local anesthetic, crystallizes in prismatic needles, readily soluble in water. When boiled with water, cocaine is hydrolyzed into benzoylecgo- nine, C 16 H 19 N0 4 , and methylic alcohol. If the hydrolysis is effected by Ba(OH) 2 , or by concentrated mineral acids, it is more complete, and ecgonine, benzoic acid and methylic alcohol are formed. Cocaine is, therefore, the methyl ester of benzoylecgonine,- and ecgonine is tropine-5-monocarboxylic acid: 428 TEXT-BOOK OF CHEMISTRY Tropidlne. H 2 C.CH- Anhydroecgouine. Tropidine-5-carboxylic acid. Tropine. N.CH 8 C ^H.COOH HOH H 2 C.CH- Ecgonine. Tropine-5-carboxylic acid. H.COO.CH, CHO.CO.C a H 6 k Cocaine. Methyl benzoylecgonate. ANALYTICAL CHARACTERS. (1) Picric acid forms a yellow ppt. in concentrated solutions. (2) A solution of iodine in KI solution gives a fine red precipitate in a solution containing 1 to 10,000 of cocaine. (3) When cocaine hydrochloride is heated with concentrated H 2 S0 4 until white fumes are given off abundantly, and potassium iodate is added to the still hot liquid, abundant violet vapors are given off, and the liquid becomes deep red-violet, changing to brilliant green, then to pink, and finally to pure blue-violet. (4) Potassium permanganate produces a violet, crystalline ppt. (5) A 5 per cent, solution of chromic acid produces an orange-colored ppt., which immediately redissolves, but, after addition of HC1, remains permanent. (6) If cocaine hydrochloride is mixed dry with HgCl, the white mixture in moist air turns gray or black. Pilocarpine gives the same reaction. Pilocarpine C n H 16 N 2 2 occurs in jaborandi, along with two other alkaloids, jaborine, C 22 H 32 N 4 4 ( ?), and pilocarpidine, C 10 H 14 - N 2 2 , and an essential oil, consisting principally of pilocarpene, C 10 H 16 . It is colorless, crystalline, readily soluble in water, alcohol, ether and chloroform. It is converted by heat into jaborine; and by HN0 3 or HC1 into a mixture of jaborine and jaborandine, C 10 H 12 - N 2 3 . Like piperine, atropine, cocaine, etc., it is ethereal in char- acter and is decomposed into C0 2 , methylamine, butyric acid, and pyridine bases by KOH or NaOH. When oxidized by potassium permanganate it yields pyridine-tartronic acid, C 6 H 4 N.C. : (OH)- (COOH) 2 , and this, on further oxidation, nicotinic acid, C 5 H 4 N.- COOH. When its hydrochloride is heated to 200, in presence of H 2 O, it takes up water and is decomposed into pilocarpidine and methylic alcohol. Conversely, pilocarpine is produced by the action of methyl iodide upon pilocarpidine. Although the constitution of pilocarpine is not established, the above and other reactions indicate that it contains the pyridine ring, to which the cyclic group, C 6 H 12 N0 2 , is attached in the ft position; and that it is methyl- pilocarpidine. Quinoline Alkaloids Cinchona Alkaloids. Although by no means so complex a substance as opium, cinchona bark contains a ALKALOIDS 429 great number of substances : quinine, cinchonine, quinidine, cinchoni- dine, aricine; quinic, quinotannic and quinovic acids; cinchona-red, etc. Of these the most important are quinine and cinchonine. Quinine Quinina (U. S. P.) C 20 H 24 N 2 2 +n Aq 324+wl8 ex- ists in the bark of a variety of trees of the genera cinchona and China, which vary considerably in their richness in this alkaloid. The best samples of calisaya bark contain from 30 to 32 parts per 1,000 of the sulphate; the intermediate 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 substance, obtained by evaporation of solutions in anhydrous alcohol or ether. The first hydrate is obtained in crystals by exposing to air recently precipitated and well-washed quinine. The second by precipitating by ammonia a solution of quinine sulphate, in which H has been previously liberated by the action of Zn upon H 2 S0 4 ; it is a greenish, resinous body, which loses H 2 at 150. The third, that to which the following remarks apply, is formed by precipitating solu- tions of quinine salts with ammonia. It crystallizes in hexagonal prisms; very bitter; fuses at 57; loses 1 Aq at 100, and the remainder at 125; becomes colored, swells up, and, finally, burns with a smoky flame. It does not sublime. It dissolves in 2,200 pts. of cold water, in 763 of hot water, very soluble in alcohol and chloroform; soluble in amyl alcohol, benzene, fatty and essential oils, and ether. Its alcoholic solution is powerfully laBvogyrous, [a.] D i= 270.7 at 18, which is diminished by increase of temperature, but increased by the presence of acids. ANALYTICAL CHARACTERS. (1) Dilute H 2 S0 4 dissolves quinine in colorless but fluorescent solution (see below). (2) Solutions of quinine salts turn green when treated with chlorine-water and then with ammonium hydroxide. (3) Chlorine passed through water hold- ing quinine in suspension forms a red solution. (4) Solution of quinine treated with chlorine-water and then with fragments of po- tassium ferrocyanide becomes pink, passing to red. SULPHATE Quininae sulphas (U. S. PO^(C 20 H 2 4p a N t ) r 18 H 2 SO 4 -H 7 Aq 746-J-126 crystallizes in prismatic needles; very light; in- tensely bitter : phosphorescent at 100 ; fuses readily ; loses its Aq at 120, turns red, and finally carbonizes; effloresces in air, losing 6 Aq ; soluble in 740 pts. of water at 13 , in 30 pts. of boiling water, and 60 pts. of alcohol. Its solution with alcoholic solution of iodine deposits brilliant green crystals of iodoquinine sulphate. HYDRO-SULPHATE Quininae bisulphas (U. S. P.) C 20 H 24 2 N 2 .- H 2 S0 4 +7 Aq 422+126 is formed when the sulphate is dissolved in excess of dilute H 2 S0 4 . It crystallizes in long, silky needles, or in short, rectangular prisms; soluble in 10 pts. of water at 15. Its 430 TEXT-BOOK OF CHEMISTRY solutions exhibit a marked fluorescence, being colorless, but showing a fine pale-blue color when illuminated by a bright light against a dark background. By the action of alkaline hydroxides upon quinine, formic acid, quinoline, and pyridine bases are produced. Concentrated HC1 at 140-150 decomposes quinine with separa- tion of methyl chloride and formation of apoquinine, C 19 H 22 N 2 2 , an amorphous base. Oxidizing agents produce from quinine oxalic acid and pyridine carboxylic acids, notably pyridine-2 3-dicarboxylic, or cinchomer- onic acid, C 5 H 3 N(COOH) 2 , which are also formed by oxidation of cin- chonine. Although cinchonine differs from quinine in composition by CH 2 0, and although the decompositions of the two bases show them both to be related to the quinoline and pyridine bases, attempts to convert cinchonine into quinine have resulted only in the formation of other products, among which is an isomere of quinine, oxycin- chonine. Methylquinine, C 20 H 24 N 2 2 CH 3 , is a base which has a curare-like action. Cinchonine Cinchonina (U. S. P.) C 19 H 22 N 2 294 occurs in Peruvian bark to the amount of from 2 to 30 pts. per 1,000. It crys- tallizes without Aq in colorless prisms; fuses at 150; soluble in 3,810 pts. of water at 10, in 2,500 pts. of boiling water; in 140 parts of alcohol, and in 40 pts. of chloroform. The salts of cinchonine resemble those of quinine in composition; are quite soluble in water and in alcohol; are not fluorescent; are permanent in air; and are phosphorescent at 100. 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 cer- tain varieties of bark, laevogyrous. At 130, H 2 S0 4 converts it into another isomere, cinchonicine. Constitution of Cinchona Alkaloids. The constitution of no cinchona alkaloid has yet been completely determined. Enough has, however, been ascertained to show that cinchonine and quinine con- tain a quinoline nucleus, united to another cyclic nucleus, containing the second N atom, and which is probably a modified piperidinc. The difference between the empirical formula? of cinchonine, C 19 H 22 N 2 0, and of quinine, C 20 H 24 N 2 2 , is CH 2 in favor of the latter, which would represent the substitution of methoxyl, CH 3 O, for H. When cinchonine and quinine are oxidized by chromic acid they yield two quinoline-carboxylic acids also differing from each other by CH,O. Cinchonine yields cinchoninic acid, which is known to be p-qumoline ALKALOIDS 431 carboxylic acid; while quinine yields quinic acid, which has been shown to be the methyl-phenol ether of p-oxyquinoline- ^-carboxylic acid (see formula?, below). Therefore the group CH 2 0, by which cinchonine and quinoline differ, exists in the quinoline ring, and the "second half," or the portion of the molecule other than the quino- line ring, is the same in the two alkaloids. This is further proved by the fact that on decomposition by PC1 5 and subsequent treatment with alcoholic KOH, cinchonine yields lepidine, C 10 H 9 N, the next superior homologue of quinoline, C 9 H 7 N, while quinine yields p- methoxy-lepidine, C 10 H 8 (OCH 3 )N, and the other product of the de- composition is one and the same substance from either alkaloid, a substance which has been called meroquinene, C 9 H 15 N0 2 , which on treatment with HgCl 2 and HC1 is converted into /?-ethyl-;/-methyl- pyridine, and whose probable constitution is expressed by the for- mula given below. So far as determined, therefore, the formula of cinchonine and of quinine are those here given, the arrangement of the group C 10 H 15 (OH)N remaining to be determined: H COOH /\\ HC C CH ml H \\/ C N H Cinchoninic acid, (y-quinoline car- boxylic acid). H COOH CH 3 (! /\\ CH 3 O.C C CH y \\/ C N Quinic acid, (3-Meth- oxyquinoline y -car- boxylic acid). C 10 H 15 (OH)N H CH a .COOH \/ C /\ /H H 2 C C< I \CH:CH a j H 2 C CH 2 \/ N Meroquinene (?) H C 10 H 16 (OH)N HC C CH 2 .CH, HC CH \\/ N 6 -Ethyl-y-methyl-pyridine. HC /\\ C CH \\/ C N Cinchonine. CH 3 C C CH I II I HC C CH V Y A Quinine. Alkaloids of the Loganiaceae Strychnos Alkaloids. This group includes strychnine and brucine and their alkyl derivatives, and the curare alkaloids. Strychnine C 21 H 22 N 2 2 exists in the seeds and bark of different varieties of Strychnos, notably Strychnos nux-vomica. It crystallizes on slow evaporation of its solutions in orthorhombic prisms ; very sparingly soluble in water and in strong alcohol ; soluble 432 TEXT-BOOK OF CHEMISTRY in 5 parts of chloroform. Its aqueous solution is intensely bitter, the taste being perceptible in a solution containing 1 part in 200,000. It is a powerful base; neutralizes and dissolves in concentrated H 2 S0 4 without coloration, and precipitates many metallic oxides from solutions of their salts. Its salts are mostly crystallizable, soluble in water and in alcohol, and intensely bitter. The acetate is the most soluble. The neutral sulphate crystallizes, with 7 Aq, in rectangular prisms. Methyl and ethyl iodides react with strychnine to produce methyl or ethylstrychnium iodides, white, crystalline substances, producing an action on the economy similar to that of curare. Heated with fuming HN0 3 , strychnine yields picric acid. Heated with baryta water to 130, it yields isostrychnic acid, C 20 H 23 N 2 O.COOH; and when treated with sodium alcoholate, strychnic acid, by addition of H 2 0. By boiling with concentrated hydriodic acid and red phos- phorus it is converted into desoxystrychnine, C 21 H 20 N 2 0, which is further reduced by electrolysis to dihydrostrychnoline, C 21 H 28 N 2 . Strychnine itself, by electrolysis, forms two bases, tetrahydro- strychnine, C 21 H 2C N 2 2 , and strychnidine, C 21 H 24 N 2 0. But little is known of the constitution of strychnine, which is, however, probably a derivative of tetrahydroquinoline. ANALYTICAL CHARACTERS. (1) Dissolves in concentrated H 2 S0 4 , without color. The solution deposits strychnine when diluted with water, or when neutralized with magnesia or an alkali. (2) If a fragment of potassium dichromate (or other substance capable of yielding nascent oxygen) is drawn through a solution of strychnine in H 2 S0 4 , it is followed by a streak of color; at first blue (very transi- tory and frequently not observed), then a brilliant violet, which slowly passes to rose-pink, and finally to yellow. Reacts with %oooo grain of strychnine. (3) A dilute solution of potassium dichromate forms a yellow, crystalline ppt. in strychnine solutions, which, when washed and treated with concentrated H 2 S0 4 , gives the play of colors indicated in 2. (4) If a solution of strychnine is evaporated on a bit of platinum foil, the residue moistened with concentrated H 2 S0 4 , the foil connected with the -f- 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 in- troduced under the skin of the back of a frog causes difficulty of respiration and tetanic spasms, which are aggravated by the slightest irritation, and twitching of the muscles during the intervals between the convulsions. With a small frog, Vioooo grain of strychnine acetate will produce tetanic spasms in ten minutes. White mice, 14 to 16 days old, are even more susceptible to the action of strychnine than frogs. (7) Solid strychnine, moistened with a solution of iodic acid in H 2 S0 4 , produces a yellow color, changing to brick-red, and then to violet-red. (8) Moderately concentrated HN0 3 colors strychnine ALKALOIDS 433 yellow in the cold. (9) A warm solution of strychnine in dilute HN0 3 produces a scarlet-red color on addition of a little KC10 3 . A drop or two of ammonia changes this to brown. On evaporation to dryness, green residue remains, which forms a green solution in water, changes to orange-brown with KOH, and returns to green with HN0 3 . TOXICOLOGY. Strychnine produces a sense of suffocation, thirst, tetanic spasms, usually opisthotonos, sometimes emprosthotonos, 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 less than twenty minutes; and death in from five minutes to six hours, usually within two hours. Death has been caused by 14 grain, and recovery has followed the taking of 20 grains. The treatment should consist in bringing the patient under the influence of chloral hydrate or of chloroform, and then washing out the stomach. The patient should be kept as quiet as possible, as the slightest unexpected irritation will produce a spasm. 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 de- composition. Brucine C 23 H 26 N 2 4 +4Aq 394+72 accompanies strychnine. It forms oblique rhomboidal prisms, which lose their Aq in dry air. Sparingly soluble in H 2 0, 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 HN0 3 colors it bright red, soon passing to yellow; stannous chloride, or colorless NH 4 HS, changes the red color to violet. (2) Chlorine-water, or Cl, colors brucine bright red, changed to yellowish-brown by NH 4 OH. Curarine C 36 H 35 N(?) is an alkaloid obtainable from the South American arrow-poison, curare, or woorara. It crystallizes in four- sided, colorless prisms, which are hygroscopic, faintly alkaline, and intensely bitter. Curarine dissolves in H 2 S0 4 , forming a pale-violet solution, which slowly changes to red. If a crystal of potassium dichromate is drawn through the H 2 S0 4 solution, it is followed by a violet colora- tion, which differs from the similar color obtained with strychnine under similar circumstances, in being more permanent, and in the absence of the following pink and yellow tints. Isoquinoline and Phenanthrene Alkaloids. The opium, hydrastis, berberis and corydalis alkaloids are included in these groups. Of the opium alkaloids, papaverine, narcotine and narceme are certainly derivatives of isoquinoline. Morphine and codeine, on the other hand, do not contain the isoquinoline nucleus, but a phenanthrene nucleus having a nitrogen-containing ring condensed upon it. But until the constitution of these two alkaloids is established with more com- 434 TEXT-BOOK OF CHEMISTRY pleteness it is not desirable to separate them from their congeners (see p. 437). Opium Alkaloids. Opium is the dried juice obtained by making incisions in the unripe capsules of the poppy, Papaver somniferum. It is of exceeding complex composition, and contains meconic, lactic and sulphuric acids, with which the alkaloids are in combination, meconine, gum, caoutchouc, wax, sugar, resins, etc., and a number of alkaloids. Some twenty alkaloids have been obtained from opium, but of these several are probably produced by the processes of ex- traction. The most important of the natural alkaloids and the average percentage in which they exist in opium of good quality are: morphine, 10%; narcotine, 6%; papaverine, 1%, codeine, 0.3%; narce'me, 0.2% ; and thebai'ne, 0.15%. Morphine Morphina (U. S. P.) C 17 H 19 N0 3 +Aq 285+18 crystallizes in colorless prisms; odorless, but very bitter; it fuses at 120, losing its Aq. More strongly heated, it swells up, becomes carbonized, and finally burns. It is soluble in 1,000 pts. of cold water, in 400 pts. of boiling water ; in 265 pts. of alcohol of 90 per cent, at 10, and in 33 pts. of boiling alcohol of the same strength; in 373 pts. of cold amyl alcohol, much more soluble in the same liquid warm ; almost insoluble in aqueous ether; rather more soluble in alcoholic ether; almost insoluble in benzene; soluble in 2,500 pts. of chloro- form at 9 , and in 45 pts. at 6 . All the solvents dissolve morphine more readily and more copiously when it is freshly precipitated from solutions of its salts than when it has become crystalline. Morphine combines with acids to form crystallizable salts, of which the hydrochloride, sulphate and acetate are used in medicine. If morphine is heated for some hours with excess of HC1, under pressure, to 150, it loses water, and is converted into a new base apomorphine, C 17 H 17 N0 2 . By heating together acetic anhydride and morphine, acetylmor- phine, C 17 H 18 (C 2 H 3 0)N0 3 , and diacetylmorphine, C 17 H 17 (C 2 H 3 0) 2 - N0 3 , are formed. The latter is used as a medicine under the name heroine. Similarly substituted butyryl-, benzoyl-, succinyl-, cam- phoryl-, methyl-, and ethyl-morphine, are also known. The last named is used medicinally under the name dionine. Morphine is readily oxidized and a strong reducing agent. It reduces the salts of gold and silver in the cold. It is oxidized by at- mospheric oxygen when it is in alkaline solution, as well as by nitrous acid, potassium permanganate, potassium ferricyanide, or ammoniacal cupric sulphate, with the formation of a non-toxic compound which has received the names, pseudomorphine, oxymorphine, oxydimor- phine, and dehydromorphine (C 17 N 18 N0 3 ) 2 , whose molecule consists of two morphine molecules, united with loss of H 2 . Morphine sulphuric acid, properly morphylsulphuric acid, or monomorphyl sulpluitc, C 18 H 18 NO 2 .O.S0 3 H, corresponds to ethyl sulphuric acid and phenyl ALKALOIDS 435 sulphuric acid, and is obtained by the same method as the latter compound from morphine. It contains H 2 less than morphine sul- phate, from which it differs in that the acidyl is attached through a hydroxyl, whereas in the salt it is attached to the nitrogen. When morphine is administered it appears in the urine as pseudomorphine, and also probably as morphylsulphuric acid, both of which are non- toxic. When morphine is distilled with powdered zinc, the principal product of the reaction is phenanthrene, accompanied by ammonia, trimethylamine, pyrrole, pyridine, and a product having the formula C 17 H 11 N, probably phenanthrene-quinoline. The salts of morphine are crystalline. The acetate is a white crystalline powder, soluble in 12 parts of water, which decomposes on exposure to air, with loss of acetic acid. The chloride is less sol- uble, but more permanent than the acetate. The sulphate is the form in which morphine is the most frequently used in medicine. It is a very light, crystalline, feathery powder; 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 . ANALYTICAL CHARACTERS. (1) It is colored orange, changing to yellow, by HN0 3 . (2) A neutral solution of a morphine salt gives a blue color with neutral solution of ferric chloride. (3) A solution of molybdic acid in H 2 S0 4 (Frohde's reagent) gives with morphine a violet color, changing to blue, dirty green, and faint pink. Water discharges the color. (4) Take two test-tubes. Into one (a) put the solution of morphine, into the other (6) an equal bulk of H 2 0. Add to each a granule of iodic acid and agitate; a becomes yellow or brown, b remains colorless. To each add a small drop of chloroform and agitate: the CHC1 3 in a is colored violet, that in b remains colorless. Float some very dilute ammo- nium hydroxide solution on the surface of the liquid in a; a brown band is formed at the junction of the layers. (5) Moisten the solid material with HC1 to which a small quantity of H 2 S0 4 has been added, and heat in an air oven at 110 until HC1 is expelled: a violet- colored liquid residue remains. Add to this a drop or two of water containing a little HC1, and neutralize with powdered sodium bicar- bonate in slight excess: a pink or rose color is produced, most dis- tinctly visible on the bubbles. Add a drop of water and a drop or two of alcoholic solution of iodine: a green color is developed. This re- action, known as the Pellagri test, is based upon the conversion of morphine into apomorphine, and consequently reacts with that alkaloid. (6) Moisten the solid with concentrated H 2 S0 4 , and heat cautiously until white fumes begin to be given off, cool and touch the liquid with a glass rod moistened with dilute HN0 3 : a fine blue- violet color, changing to red and then to orange. If the H 2 S0 4 con- tains oxides of nitrogen, as it usually does, a violet tinge will be pro- 436 TEXT-BOOK OF CHEMISTRY duced before addition of HN0 3 , but then becomes much more intense. This reaction, known as the Husemann, may be applied by allowing the solid to remain in contact with H 2 SO 4 for fifteen to eighteen hours in place of heating. (7) Marquis' reagent (3 cc. concentrated H 2 S0 4 +2gtt. formaline) gives a brilliant red-violet color. These are the most important tests for morphine, and affirmative results with all of them prove the presence of that alkaloid. There are many others. Codeine Codeina (U. S. P.) C 18 H 21 N0 3 +Aq 299+18 crys- tallizes in large rhombic prisms, or from ether, without Aq, in octa- hedra; bitter; soluble in 80 pts. cold water; 17 pts. boiling water; very soluble in alcohol, ether, chloroform, benzene; almost insoluble in petroleum-ether. Codeine is the methyl ether of morphine, or its superior homo- logue, and resembles that alkaloid in some of its reactions; thus under similar circumstances both form apomorphine ; and morphine may be converted into codeine by the action of methyl iodide in the presence of KOH. Codeine, however, only contains one OH group, and forms a monoacetyl derivative with acetyl chloride, while mor- phine produces a diacetyl compound. Narceine C 23 H 27 N0 8 +2Aq 463+36 crystallizes in bitter, prismatic needles ; sparingly soluble in water, alcohol, and amyl alco- hol; insoluble in ether, benzene, and petroleum-ether. Narcotine C 22 H 23 N0 7 413 crystallizes in transparent prisms, almost insoluble in water and in petroleum-ether; soluble in alcohol, ether, benzene, and chloroform. Its salts are mostly uncrystallizable, unstable, and readily soluble in water and in alcohol. Narcotine is decomposed by H 2 at 140, by dilute H 2 S0 4 , or by baryta, with formation of opianic acid, C 10 H 10 5 , and hydrocotar- nine, C 12 H 15 N0 3 . Reducing agents decompose it into hydrocotarnine and meconine, C 10 H 10 4 . Oxidizing agents convert it into opianic acid and cotarnine, C 12 H 13 N0 3 . Papaverine C 20 H 21 N0 4 crystallizes in prisms; almost insoluble in water, easily soluble in chloroform and in hot alcohol. It is optically inactive. It forms a colorless solution with concentrated H 2 S0 4 , which turns dark-violet when heated. Acetic anhydride has no action upon it. Thebaine Paramorphine C 19 H 21 N0 3 311 crystallizes in white plates; tasteless when pure; insoluble in water, soluble in alcohol, ether and benzene. Apomorphine C 17 H 17 N0 2 is used hypodermically as an emetic in the form of the chloride. It is obtained by sealing morphine, with an excess of strong HC1, in a thick glass tube, and heating the whole to 140 for two to three hours. It is obtained 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 greenish tint on ex- ALKALOIDS 437 posure to light and air. It is odorless, bitter and neutral; soluble in 6.8 parts of cold water. Relations and Constitution of the Opium Alkaloids. The al- kaloids of opium may be arranged in two groups: (I) Including those which are strong bases, are highly poisonous, and contain three or four atoms of oxygen; (II) those which are weak bases and con- tain four to nine oxygen atoms. So far as known, the alkaloids of the first group contain the phenanthrene-pyridine nucleus, while those of the second group are derivatives of isoquinoline. The six prin- cipal alkaloids above mentioned are equally divided between the two groups : I. II. Morphine C 17 H 19 N0 3 Papaverine C 20 H 21 NO 4 Codeine C 18 H 21 N0 3 Narcotine C 22 H 23 NO 7 ThebaTne C 19 H 21 N0 3 Narcei'ne C 23 H 2T N0 8 Papaverine was first recognized as an isoquinoline derivative. On oxidation of papaverine by potassium permanganate, papaveraldine, C 20 H 19 N0 5 , is formed. This, on fusion with caustic potash, yields veratric acid, which is 3, 4-dimethoxy-benzoic acid, C 6 H 3 .COOH: (OCH 3 ) 2(3 4) , and dimethoxy isoquinoline, the constitution of the latter being established by its further decomposition into metahemipinic acid andtf-^-x-pyridine-tricarboxylic acid. The relations of papa- verine and its products of decomposition are shown by the following formulae : COOH H HC CH H 3 CO C C COOH HC C OCH 3 H 3 CO C C COOH V V OCH 3 H Veratric acid, Metahemipinic acid, (3, 4-Dimethoxy -benzole acid). (4, 5-Dimethoxy-o-phthalic acid). H /\\ N HC CH V V /AN HOOC C CH HOOC C N \ // C COOH HC C OCH 3 C OCH 3 Papaverine, (Tetramethoxy-benzyl-a-isoquinoline) . a-j8-y-Pyridine-tricarboxylic acid. 438 TEXT-BOOK OF CHEMISTRY Narcotine, C 22 H 23 N0 7 , is converted by oxidation into opianic acid, C 10 H 10 5 (p. 436), and cotarnine, C 12 H 15 N0 4 . By hydrolysis it yields 'opianic acid and hydrocotarnine, C 12 H 15 NO 3 ; and by reduction, meco- nine, C 10 H 10 4 (p. 436), and hydrocotarnine. Narcotine, therefore, contains the nuclei of opianic acid, or of meconine, and of hydro- cotarnine. The constitution of opianic acid is known, as well as that of its reduction product, meconine, but that of hydrocotarnine is not completely established. It is, however, a derivative of iso- quinoline, containing one of the three methoxy groups (CH 3 0) which exist in narcotine, and a bivalent group O.CH 2 .0 attached to the benzene ring; and a methyl group, united to the N atom in the pyridine ring. Narcei'ne, C 23 H 27 N0 8 is formed by the action of caustic potash upon narcotine iodomethylate : C 22 H 23 N0 7 .CH 3 I + KOH = KI+ C 23 H 27 N0 8 . Narce'ine apparently does not contain an isoquinoline grouping, that which exists in narcotine having been broken in the above method of formation in such manner that the N is in a lateral chain in narceine. Morphine, C 17 H 19 N0 3 , and codeine, C 18 H 21 N0 3 , are closely related. Codeine is produced by the action of methyl iodide upon morphine- potassium: C 17 H 18 KN0 3 +CH 3 I=KI+C 17 H J8 (CH 3 )N0 3 . It is, there- fore, methyl-morphine. By the further action of methyl iodide upon codeine in alcoholic solution, codeine methyl iodide, C 18 H 21 N0 3 :CH 3 I, is produced, and this, when warmed with KOH, is converted into methyl-morphine methine, C 17 H 19 N0 3 :CH.CH 3 . The last-named substance is decomposed by acetic anhydride into methyldioxyphen- anthrene and oxethyl-dimethyl-amine : C 17 H 19 N0 3 :CH.CH 3 =C 14 - /OTT ' *-'-H 3 H 8 ( X PIT + N CH 3 ; and other morphine and codeine deriva- *\O.CH 8 ^ \CH 2 .CH 2 .OH tives are similarly decomposed, with formation, on the one hand, of a non-nitrogenized oxy-phenanthrene compound, and, on the other, an oxyamine or a trialkyl-amine. Upon these facts, it is concluded, that the morphine and codeine molecules consist of an oxyphenanthrene CH 3 /\ group, upon which is fused a nitrogenized group, 2 , . It is also H 2 C \ / O recognized that the two hydroxyls are in the same phenanthrene ring, and that one of them is phenolic, the other alcoholic; also that one methyl group is attached to the nitrogen atom. The disposal of the hydrogen and hydroxyls in the phenanthrene nucleus and the position of attachment of the nitrogenized group above referred to remain undetermined. Two formulae of constitution of morphine have been proposed, either of which is in consonance with the known facts : ALKALOIDS 439 OH I OH /\\ HOHC CH / \\ HOHC CH C || \ // \ HC C H 2 C s C CH 2 \ // \ H 2 C C i O C CH 2 III ' \ / \\ / H 2 C C i H 2 C C C \ / \\ / C CH H 3 C N HC C H 2 C C CH \ / \ // H 2 C CH N C \// I ! c CH 3 H H (I) (ID The formula of codeine is derived from either formula by substitu- tion of CH 3 for H in the phenolic OH; that of apomorphine by removal of H 2 0. Thebaine, C 19 H 21 N0 3 , is decomposed by acetic anhydride in a manner quite analogous to the decomposition of morphine, above re- ferred to, but yielding a dimethoxy-phenolic derivative of phenan- threne, called thebaol, and methyl-oxethyl-amine : C 19 H 21 N0 3 +H 2 0= /H (CH 3 0) 2 C 14 H 7 .OH+N CH 3 . Like morphine and codeine, it \ CH 2 .CH 2 .OH is therefore a phenanthrene-pyridine derivative. Toxicology of Opium and its Derivatives. Opium, its preparations and the alkaloids obtained from it are all active poisons. The alkaloids have not all the same action. In soporific effects, beginning with the most powerful, they rank thus: narcotine, morphine, codeine; in tetanizing action: theba'iine, papaverine, narcotine, codeine, morphine ; in toxic action : thebai'ne, codeine, papaverine, narce'ine, morphine, narcotine. The symptoms set in from ten minutes to three hours, exceptionally " immediately," or only after eighteen hours. They are divisible into three periods: (1) a stage of excitement, marked by great physical activity, loquacity and imaginative power ; is of short duration ; longest in opium habitues, absent with large doses; (2) a period of sopor, in which there are diminished sensi- bility, weariness, contracted pupils, pale face, livid lips, drowsiness, increasing to deep sleep, from which, however, the patient may be roused, and when so roused is coherent in speech. This stage merges insensibly into the third, that of coma. The patient can no longer be aroused, even by violent means. The face is pale, the lips cyanosed, the muscular system completely relaxed, the reflexes abolished, the pupils contracted greatly, and insensible to light, the pulse slow, irregular, compressible, and finally imperceptible, the res- piration more and more infrequent, stertorous, shallow, and accompanied by mucous rales. Retention of urine begins early in the poisoning. The usual duration of a fatal poisoning is from six to twenty-four hours. Deaths have occurred in forty-five minutes and in three days. The minimum lethal dose for a non-habituated adult is probably 3 to 4 grains. Young children are very susceptible. Tolerance to a remarkable degree 440 TEXT-BOOK OF CHEMISTRY is established by habit, both in children and in adults, and instances are re- ported in which 50 to 60 grains have been taken daily, without toxic effects, by morphine takers. The treatment should consist in washing out the stomach with a dilute solution of potassium permanganate, leaving about 500 cc. in the stomach, and in maintaining the respiration. In the first or second stage the " ambulatory treatment " should be adopted to prevent, if possible, the establishment of the third stage. If this stage develops, the main reliance is to be placed in main- taining the respiration by artificial methods, until the poison has been elimi- nated. Strong coffee, or caffeine, by the mouth or rectum are of benefit. The same cannot be said of atropine. The urine should be drawn by the catheter. The opiates leave no post-mortem lesions, except such as are usually observed after death from asphyxia, i.e., congestion of the vessels of the brain and meninges, and of the lungs, and a dark, fluid condition of the blood. Alkaloids of unknown constitution. Of the numerous alkaloids whose constitution is insufficiently known to permit of their classifi- cation, only a few can be here briefly considered: Alkaloids of the Aconites. The different species of Aconitum contain probably a number of alkaloids, but our knowledge of them is as yet extremely imperfect. The substances described as aconitine, lycoctonine, napelline are impure. It appears, however, that the prin- cipal alkaloids of Aconitum napellus and of A. ferox, although differ- ing from each other, are both compounds formed by the union of aconine, C 25 H 41 N0 9 , with the radical benzoic acid in the former and with that of veratric acid in the latter. Aconitine Acetylbenzoyl-aconiner C 25 H 3? (CH S .CO) (C 6 H 5 .CO) N0 9 the principal alkaloid of A. napellus, is a crystalline solid, almost insoluble in water, and very bitter. It is decomposed by H 2 at 140 and by KOH into aconine and acetic and benzoic acids. It is very poisonous. Pseudo-aconitine C 36 H 49 N0 12 occurs in A. ferox. It is a crys- talline solid, having a burning taste, and is extremely poisonous. On decomposition by H 2 at 140 it yields aconine veratric acid. Japaconitine C 66 H 88 N 2 21 has been obtained from the root of A. japanicum, and is a crystalline solid which is decomposed by alkalies into benzoic acid and japaconine, C 2fi H 4 iN0 10 . The color reactions described as characteristic of "aconitine" are not due to the alkaloid. 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, great muscular feebleness, giddiness, loss of speech, irregularity and failure 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 ALKALOIDS 441 the stomach-pump, and washing out of the stomach with infusion of tea holding powdered charcoal in suspension. Stimulants should be freely administered. Alkaloids from other Sources. Ergotine C 50 H 52 N 2 3 and Ecboline are two brown, amorphous, faintly bitter, and alkaline alkaloids obtained from ergot. They are readily soluble in water and form amorphous salts. The medicinal preparations known as ergotine are not the pure alkaloid. Colchicine C 17 H 19 N0 5 occurs in all portions of Colchicum autumnale and other members of the same genus. It is a yellowish- white, gummy, amorphous substance, having a faintly aromatic odor and a persistently bitter taste. It is slowly but completely soluble in water, forming faintly acid solutions. It forms salts which are, how- ever, very unstable. Concentrated HN0 3 , or, preferably, a mixture of H 2 S0 4 , and NaN0 3 , colors colchicine blue-violet. If the solution is then diluted with H 2 0, it becomes yellow, and on addition of NaOH solution, brick-red. Veratrine Veratrina (U. S. P.) C 32 H 52 N 2 8 occurs in Vera- trum officinale=Asagrcea officinalis, accompanied by Sabadilline C 20 H 26 N 2 5 Jervine C 30 H 46 N 2 3 and other alkaloids. The sub- stance to which the name Veratrina, U. S. P., applies is not the pure alkaloid, but a mixture of those occurring in the plant. Concentrated H 2 S0 4 dissolves veratrine, forming a yellow solu- tion, turning orange in a few moments, and then, in about half an hour, bright carmine-red. Concentrated HC1 forms a colorless solu- tion with veratrine, which turns dark-red when cautiously heated. Physostigmine Eserine C 15 H 21 N 3 2 is an alkaloid existing in the Calabar bean, Physostigma venenosum. It is a colorless, amor- phous solid, odorless and tasteless, alkaline and difficultly soluble in water. It neutralizes acids completely, with formation of tasteless salts. Its salicylate Physostigminae salicylas, U. S. P. forms short, colorless, prismatic crystals, sparingly soluble in water. Concentrated H 2 S0 4 forms a yellow solution with physostigmine or its salts, which soon turns olive-green. Concentrated HN0 3 forms with it a yellow solution. If a solution of the alkaloid in H 2 S0 4 is neutralized with NH 4 OH, and the mixture warmed, it is gradually colored red, reddish-yellow, green, and blue. Emetine C 28 H 40 N 2 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 H 2 S0 4 , 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. 442 TEXT-BOOK OF CHEMISTRY PTOMAINES, LEUCOMAINES AND TOXINES. The name ptomaine, derived from Trry/za ("that which has fallen," i.e., a corpse), was first suggested by Selmi in 1878 to apply to a substance, or class of substances, first distinctly recognized, although not isolated, by him, which are produced by saprophytic bacteria from proteins during putrefaction. The ptomaines are sometimes referred to as " animal alkaloids," a term which is mis- leading, as they are produced from vegetable as well as from animal proteins, and but few of them are alkaloids in the present acceptation of the term (p. 419). The great majority, and those the best known, are monamines, diamines, guani- dines, hydramines, betai'nes, or amido acids. The term " ptomaines " does not therefore apply to the members of a distinct class of chemical compounds, but to the bacterial origin of substances belonging to several distinct chemical classes and also obtainable by other methods, having in common only the two qualities that they are basic and contain nitrogen. But some ptomaines are true alkaloids. Some of the superior homologues of pyridine are putrid products. A base C 8 H n N, isomeric with collidine, formed during putrefaction of jelly-fish, on oxidation yields nicotinic acid, C 5 H 4 N(COOH), which is also similarly produced from nicotine (p. 423), and also forms a chloroplatinate and an iodomethylate which have the characteristic properties of the like compounds produced from the pyridine bases and vegetable alkaloids. Other basic substances obtained from brown cod-liver oil, and probably formed by a modified putrefaction, are hydropyridine derivatives. Among these are a dihydrolutidine, C 7 H n N, a dihydrocollidine, C s Hi S N, and a complex hydropyridic oxyacid, called morrhuic acid, HO.C 3 H 5 N.C 3 H 6 .COOH. Indole and skatole, products of putrefaction, also come within the definition of alkaloids. A ptomaine may be defined as a basic compound, containing nitrogen, produced from protein material by the bacteria which cause putrefaction. Owing to the wide variationc in the chemical constitution of the ptomaines, they possess no characters by which they can be distinguished as a class. Some are strongly alkaline and basic, others only feebly so. Some are liquid, oily and volatile, others fixed and crystalline. Some are very prone to oxidation, and are active reducing agents, others are quite stable. For the same reason, no analytical method is possible by which vegetable alkaloids and ptomaines can be separated from each other en masse, nor are any reactions known to which all ptomaines respond while vegetable alkaloids do not, or the reverse; nor are such reactions to be expected. Certain classes of ptomaines may be identified or separated from vegetable alkaloids, but not all. Thus those which arc diamines may be separated by formation of their benzoyl derivatives, but only a few ptomaines are diamines. Those ptomatnes which are reducing agents ^ive a blue color with a mixture of ferric chloride and potassium ferricyanide but all ptomaines do not reduce, and some vegetable alkaloids, such as morphine and veratrine, do. It was feared that the existence of ptomaines, whoso forma- tion begins shortly after death, and also occurs during life, might render flu- detection of vegetable poisons in the cadaver impossible. Such fears were by no means groundless, as thero is abundant evidence that ptomaTnos have boon mistaken for vegetable alkaloids in chemico-lepral analyses. It is. however, possible to positively and certainly predicate the existence or non-existence in a cadaver of a given vegetable alkaloid, provided it has a sufficient number of characteri/inj; reactions, hut. it can only be done after a thorough and con- scientious examination by all physiological and chemical reactions. Leucomames are nitrogenous, basic substances which are produced in the bodies of animals during life as results of normal chemical processes. They ;n- excreted in hc;il1h. and if retained exert deleterious actions, more or less intense. The xanthine, or purine, liases and those of the creatine group are PTOMAINES, LEUCOMAINES, AND TOXINES 443 leucomai'nes, and others occur in the urine. But, as some leucomalnes, such as choline, tyrosine, and betaine, are also ptomaines, being produced by saprophytic bacteria., the line of distinction cannot be sharply drawn. Toxines. The name "toxine" was first used by Brieger, and by him applied to poisonous ptomaines and other toxic, basic, nitrogenous substances, obtained from the culture media of pathogenic bacteria or from animal organisms. Such are the four basic substances obtained from the culture media of the tetanus bacillus: Tetanine, C 13 H n N 2 O4, a yellow, strongly alkaline syrup; Tetanotoxine, C 5 H n N ( ? ) , a volatile oil ; Spasmotoxine, and another unnamed base of un- determined composition, all of which form deliquescent hydrochlorides, and very soluble, crystalline platinochlorides. These bases, when injected into animals, cause clonic or tonic convulsions of great intensity, terminating in death. But it has been shown that the cultures from which these basic sub- stances are obtainable, after filtration through porcelain, are vastly more toxic than the combined bases. These therefore can only constitute a small fraction of the active material produced by the bacilli, and the more virulent, non-basic product is a toxine in the more modern sense. In this latter sense the toxines are poisonous substances of unknown chemi- cal composition produced by bacteria or other cells. They are not products of decomposition of the proteins, as are the ptomaines, but synthetic products, secretions, as it were, of the bacteria. They are not all members of the same chemical class. Some, the extracellular toxines, so called because they pass in great part into the culture media, have many resemblances to the albumoses. They are non-crystalline, soluble in water, and dialysable, are precipitated by alcohol and by ammonium sulphate, and lose their virulence when heated. The toxines of diphtheria and tetanus belong to this class. But little is known of the properties of the intracellular toxines, which are largely retained in the bacterial cells until these are destroyed, except that they do not dialyse, and are more resistant to heat than the extracellular toxines. The toxines of typhoid, tubercle and glanders belong to this second class. The toxalbumins are substances obtained from certain seeds or secreted by animals, which are highly toxic, and have the general properties of albumoses or of globulins. They therefore differ from the toxines solely in that they are not of bacterial origin, and, furthermore, they resemble bacterial poisons more closely than vegetable alkaloids in their actions, particularly in the latent period preceding the manifestation of their effects. Putrefaction is the decomposition of dead protein material under the in- fluence of certain bacteria, attended by the evolution of more or less fetid products. In order that it may occur, certain conditions are necessary: (1) The presence of living bacteria, or of their germs; (2) the presence of moisture; (3) a temperature between 5 and 90; (4) an atmospheric condition suitable to the growth of the bacteria. Some of the several species of bacteria which cause putrefaction are aerobic, i.e., require the presence of air for their de- velopment, while others are anaerobic, i.e., they thrive best in the absence of oxygen. Proteins which have been deprived of moisture, either by drying or by the action of dehydrating agents, such as strong alcohol, do not enter into putrefaction unless water is supplied to them, when the process proceeds as usual. The temperature most favorable to putrefaction is about 40. High or low temperatures arrest putrefaction or prevent it, the former, if sufficiently high, permanently (if the material is protected from new bacteria) by de- stroying the vitality of the bacteria; the latter, even if extreme, only tempo- rarily, and so long as the low temperature is maintained. Putrefaction may, therefore, be prevented either (1) by the action of agents or substances which interfere with the development of bacteria (germi- cides and antiseptics) ; (2) by the exclusion of air; (3) by the exclusion of water; (4) by a temperature below 5 or above 90. 444 TEXT-BOOK OF CHEMISTRY Putrefaction is attended by the breaking down and liquefaction of the material if it is solid; or its clouding and the formation of a scum upon the surface if it is liquid. The products of putrefaction vary with the conditions under which it occurs. The most prominent are: (1) inorganic products such as N, H, H 2 S, NH 3 , and simple organic compounds, such as CO, and hydro- carbons; (2) acids of the fatty series in great abundance, and acids of the oxalic and lactic series; (3) non-aromatic monamines and diamines, such as trimethylamine, putrescine, and certain of the ptomaines; (4) aromatic prod- ucts, among which are: (a) phenols, such as tyrosine, oxyaromatic acids, phenol, and cresol; (6) phenylic derivatives, such as phenyl acetic and phenyl propionic acids; (c) indole, skatole, skatole-carbonic acid, etc.; (d) ptomaines of undetermined constitution, but belonging to the aromatic series; pyridine derivatives. Under certain imperfectly defined conditions buried protein material does not undergo ordinary putrefaction, but is converted into a substance resembling tallow, and called adipocere, which consists chiefly of ammonium palmitiitc, stearate and oleate, calcium phosphate and carbonate, and an undetermined nitrogenous substance. Germicides are substances or agents which destroy bacteria and their germs. Mercuric chloride and heat are germicides. Antiseptics are substances which prevent or restrain putrefaction. Antiseptics are either germicides, which prevent putrefaction by destroying the organisms which cause it, or are agents, which interfere with the develop- ment of these organisms without destroying their vitality. The salts of aluminium are antiseptic by reason of their chemical action on the proteins, although their germicidal powers are slight. Deodorizers, or air purifiers, are substances which destroy the odorous products of putrefaction. Disinfectants are substances which restrain infectious diseases by de- stroying or removing their specific poisons. APPENDIX TABLE OF SOLUBILITIES FRESENIUS. W or w = soluble in H 2 0. A or a = insoluble in H 2 ; soluble in HC1, HN0 3 , or aqua regia. I or i = insoluble in H 2 and acids. W-A = sparingly soluble in H 2 0, but soluble in acids. W-I = sparingly soluble in H 2 and acids. A-I = insoluble in H 2 0, spar- ingly soluble in acids. Capitals indicate common substances. Aluminium. Ammonium. Antimony. Barium. Bismuth. Cadmium. Calcium. Chromium. Cobalt. M O> ! Ferrous. *C 1 Acetate W W W w w W w w \Y W Arsenate Arsenite a w w a a a a a a a a a a a a A a a a a Benzoate w w w W w a w Borate a w a a w-a a a a a Bromide W w w-a w-i Carbonate a W A A a A a A A A a Chlorate W w w w w w w w Chloride W 3 W-A* W W-A 10 W W \V-I W Chromate .... w a a a a w-a a a w w Citrate w w a a w-a w \v w Cyanide w w-a a w a a-i a a-i Ferricyanide . . Vf w i I w Ferrocyanide . w w-a w j j i T Fluoride .... W w a-i w w-a A w \V-ll a \v-a Formate w w w w AV w w w w w w Hydrate A W A VV a a \\ - \ A A a a A Iodide W w a W w w w \v W Malate . w w w-a Nitrate w W W W 11 w w W \Y \V W W Oxalate a W a a a a A w-a A a a a Oxide Phosphate Silicate A-] a A-I w a 7 w-a W w-a a a a a a a W-A W-A t A-I a a A a a A a a a a a A a a \v-a w w-a w W-'l \v-;i \v Sulphate W 1 W 4 a A w W W-I W-A 12 W" W W W Sulphide a w A 8 W a A W-A a-i a A A A Tartrate w w a 9 a a w-a a \v w \v \v-a W*' 1 (A1 2 )(NH 4 ) 2 (S0 4 ) 4 =W; (A1 2 )K (S0 4 ) 4 =W. 2 As(NH 4 )Cl 4 = W; Pt(NH 4 )Cl r) =W-I. 3 HNa(NH 4 )P0 4 =W; Mg(NH 4 )P0 4 =A. 4 Fe- (NH 4 ) 2 (S0 4 ) 2 =W ; Cu(NH 4 ),(S0 4 ),=W. 5 C 4 H 4 O r ,K(NH 4 )=W. 6 SbOCl=A. 7 Sb 2 3 =soluble in HC1, not in HNO,. 8 Sb.,S,=sol. in hot HC1, slightly in HN0 3 . 8 C 4 H 4 O fi K(SbO)=W. 10 BiOCl=A. n (BiO) NO,=A. 12 (Cr 2 )K (S0 4 ) 4 =W. 13 CoS=easily sol. in HN0 3 , very slowly in HC1. u (C 4 H 4 6 ) 4 (Fe 2 )K 1 =:W. SOLUBILITIES 447 TABLE OF SOLUBILITIES. Continued. FRESENIUS. W or w = soluble in H 2 0. A or a insoluble in H 2 ; soluble in HC1, HN0 3 , or aqua regia. I or i = insoluble in H 2 and acids. W-A = sparingly soluble in H 2 0, but soluble in acids. W-I = sparingly soluble in H 2 and acids. A-I = insoluble in H 2 0, spar- ingly soluble in acids. Capitals indicate common substances. s E 1 5 w a a w w-a w A w W w w w w w a-i w A w w w a A a 3 a w W a w-a 1 1 W a a w a w A w W w a a i a a w a w w w w-a A 15 a a w W a w-a P jo p | Mercurous. Mercuric. w a a a w A w W a w a-i i i w-a w a w W a A a a w W A 19 a Potassium. i Sodium. Strontium. p P ^ Stannous. 1 w a G N Acetate w a a a a w-i A w W-I A-I a a w-a a a w-a a W-A w-a W a A a a a A-I A a w a a w-a W W w w W W W W W 20 W w W W W w w W W w W W w w W w W 12 W W w a a w-a a a a w I a a i i i w w i w-a W a a a a W-A a 21 a W W w w W W W w W w W w w w w w W w w W W W W W w W W w w a a W Arsenate Arsenite Benzoate Borate a w A w W w-a a w a a w A w W w w-a a a a-i w-a w a w w w a A a a w-a W A 23 a Bromide Carbonate Chlorate Chloride a-i a w A-I a a w a w W 18 w-a w-a W w W a "w* Chromate Citrate Cyanide .... Ferrocyanide Fluoride Formate w a-i w w w w W a W a a w-a I w a w w-a w w w a w w w a w w Hydrate Iodide A a W a A a A w-a W a A a Malate Nitrate Oxalate a a a w A-I a Oxide Phosphate Silicate. .... Succinate a w-a a w-a w-a W 17 A 18 a w a 22 a a A" Sulphate Sulphide Tartrate 15 Mn0 2 =sol. in HC1 ; insol. in HN0 3 . 16 Mercurammonium chlo- ride=A. 17 Basic sulphate=A. 18 HgS=insol. in HC1 and in HN0 3 , sol. in aqua regia. 19 See 13. , 20 PtKCl 5 =W-A. 21 0nly soluble in HN0 3 22 Sn sulphides=sol. in hot HC1; oxidized, not dissolved, by HNO 3 . Sublimed SnCl 4 only sol. in aq. regia. 23 Easily sol. in HN0 3 , difficultly in HC1. Au 2 S=insol. in HC1 and in HN0 3 , sol. in aq. regia. AuBr 3 , AuCl 3 , and Au(CN) 3 =w; AuI 3 =a. PtS 2 =insol. in HC1, slightly sol. in hot HN0 3 ; sol. in aq. regia. PtBr 4 , PtCl 4 , Pt(CN) 4 , Pt(N0 3 ) 4 , Pt(C 2 4 ) 2 , Pt(S0 4 ) 2 =w; Pt0 2 =a;PtI/=i. INDEX INDEX INDEX Absolute temperature, 13. zero, 13. Absorption of gases, 11. Acetal, 233. Acetaldehyde, 229. Acetaldoxime, 320. Acetals, 232. Acetamide, 312. Acetanilide, 372. Acetates, 253. Acetol salicylate, 358. Acetonamines, 319. Acetone, 234. diethylsuphone, 287. dimethylsulphone, 287. Acetonemia, 235. Acetones, 233. Acetonitrile, 305, 306, 313. Acetophenone, 355. oxime, 355. Acetophenyl hydrazide, 381. Acetoxime, 320. Acetoximes, 320. Acetyl benzene, 355. benzoylaconine, 440. chloride, 270. hydroxide, 252. morphine, 434. Acetylene, 329. series, 201, 329. Acetylide, 329. Achroodextrins, 246. Acid (see also Acids). acetic, 252. acetoacetic, 266. acetohydroxamic, 301. acetylamidoacetic, 323. aconitic, 265. acrylic, 330, 331. allophanic, 317. amidoacetic, 323 (see Glycocoll). amidobenzoic, 356. amidoformic, 313, 322 (see Acid, Carbamic ) . amidoisobutylacetic, 325. amidovaleric, 325. amygdalic, 362. Acid anhydrides, 269. Acid, anilidoacetic, 375. anilindisulphonic, 371. anilpyroracemic, 376. anthranilic, 356, 374. antitartaric, 264. arachic, 256. Acid, arsenic, 113, 115. arsenous, 113. auric, 129. barbituric, 404. benzenedicarboxylic, 357. benzenemonosulphonic, 366. benzene sulphonic, 341. benzene trisulphonic, 366. benzhydroxamic, 376. benzoic, 356. benzoylamidoacetic, 375 (see Acid, hippuric ) . boracic, 124. boric, 124. butan, 253. butyric, 253. cacodylic, 327. cachoutannic, 360. caffeic, 360. caffetannic, 360. capric, 255. caprylic, 255. carbamic, 313. carbanilic, 375. carbazotic, 369. carbolic, 345 (see Phenol), carbonic, 261. chelidonic, 397. chloric, 79. chromic, 131. cinchomeronic, 430. citraconic, 265. citric, 265. comenic, 397. cumic, 356. cyanic, 307. cyanuric, 307, 315. decylic, 255. dextrolactic, 262. dextrotartaric, 264. diacetic, 266. dialuric, 404. dichloracetic, 253. dichromic, 131. digallic, 360. dihydrocyanic, 310. dimethylacetic, 254. dinitronaphtholsulphonic, 387. dioxybenzoic, 359. dioxycinnamic, 360. dioxymalonic, 266. disulphanilic, 371. dithiocarbamic, 316. elai'dic, 332. 451 452 INDEX Acid, erythroglucic, 225. ethan, 252. ethidenelactic, 262. ethidenepropionic, 331. ethylacetic, 253. ethylenelactic, 263. ethylsulphonic, 277. ethylsulphuric, 268, 277. formic, 251. fulminic, 307. fulminuric, 308. fumaric, 332. furfurane carboxylic, 392. gadinic, 282. gallic, 359. glucovanillic, 362. glucuronic, 266. glutaric, 259. glycerophosphoric, 281. glycolamic, 323. glycollic, 262. glycoluric, 318. glycosuric, 35!). glyoxalineamidopropionic, 396. glyoxylic, 265. graphitic, 125. Acid halides, aliphatic, 270. aromatic, 364. Acid, hexahydro-tetroxybenzoic, 384. hippuric, 375. homogentisinic, 359. homoprotocatechuic, 359. hydantoic, 317, 318. hydracrylic, 263. hydrazoic, 97. hydriodic, 82. hydrobromic, 80. hydrochloric, 76. hydrochloroplatinic, 148. hydrocyanic, 303. hydrofluoric, 73. hydrofluosilicic, 127. hydronitroprussic, 310. hydrosulphurous, 89. hypobromous, 81. hypochlorous, 79. hyponitrous, 100. hypophosphoric, 109. hypophosphorous, 108. hyposulphurous, 89, 92. indoleacetic, 416. indoleamidopropionic, 416. indoxylic, 417. indoxylsulphuric, 417. iodic, 83. isethionic, 286. isobarbituric, 407. isobutyric, 254. isocyanic, 318. isodialuric, 407. isoplillialic, :5f>7. isopropvlacctic. 254. isopropylbenzoic, 356. Acid, isostrychnic, 432. isothiocyanic, 308. isovalcric, 254. itaconic, 265. lactic, 262. Ircvolactic, 263. laevotartaric, 264, 205. laevulinic, 347. lauric, 255. laurostearic, 255. lithic, 406. maleic, 332. malic, 263. malonic, 258. mannosaccharic, 265. margaric, 255. meconic, 397. mesotartaric, 264, 265. mesoxalic, 266. metaboric, 124. metanitrous, 101. metantimonic, 122. metantimonous, 122. metaphosphoric, 109. metarsenic, 114. metarsenous, 113. metastannic, 146. metatungstic, 128. methan, 251. methylacetic, 253. methylethylamido propionic, 325. metliylguanidinacotie, 302. monochloracetic, 253. morintannic, 300. morphinesulphuric, 434. morphylsulphuric, 434. morrhiiio, 442. mucic, 265. muriatic, 76. myristic, 255. myronic, 363. nitric, 101. nitroacetic, 321. nitrohydrochloric, 102. nitrosonitric, 102. nitrosulphonic, 99. nitrous, 101. octylic, 255. oleic, 331. opianic, 436. orthoamidobenzoic, 374. orthoantimonic, 122. orthoarsenic, 113. orthoboric, 124. orthorarbonic, 109. orthoformio. 252. ortbopbcnylaulpbonic, 366. orthophosphoric, 108. osmic, 12S. oxalic, 257. oxaluric, 318. oxanilic, 374, 375. INDEX 453 Acid, oxyacetie, 202. oxybfctyric, 263. oxyformic, 261. oxyglutaric, 263. oxyhydratropic, 364. oxymalonic, 263. oxyphenic, 349. oxypropionic, 262, 263. oxysuccinic, 263. palmitic, 255. paraamidobenzenesul phonic, 371. parabanic, 395. paralactic, 262. paratartaric, 264. pentathionic, 89. perchloric, 79. periodic, 83. persulphuric, 92. phenic, 345. phenylacetic, 356. phenylamidopropionic, 374. phenylmalonic, 356. phenylsulphuric, 366. phloretic, 364. phosphatic, 109. phosphomolybdic, 128. phosphoric, 108. phosphorous, 108. phosphotungstic, 128. phthalamic, 373. phthalic, 357. picric, 369. propan, 253. propionic, 255. propylacetic, 254. prussic, 303. purpuric, 404. pyridinedicarboxylic, 430. pyridinetartronic, 428. pyroantimonic, 122. pyroarsenous, 113. pyroboric, 124. pyrocateehnic, 359. pyrogallic, 350. pyromucic, 392. pyrophosphoric, 109. pyroracemic, 266. pyrosulphuric, 93. pyrotartaric, 259, 264. pyruvic, 264, 266. quercitarmic, 360. quinic, 384, 429. quinotannic, 360, 429. quinovic, 429. racemic, 264, 265. Acid reaction, 32. Acid, rosolic, 350. saccharic, 265. salicylic, 358. salicylous, 354. sarcolactic, 262. sebasic, 332. silicotungstic, 128. Acid, sozolic, 366. stannic, 146. stearic, 255. strychnic, 432. succinic, 259. sulphanilic, 371. sulphydric, 85. sulphocarbamic, 316. sulphocyanic, 308. sulphovinic, 268, 277. sulphuric, 90. sulphurous, 89. tannic, 360. tartaric, 239, 264, 265. tartronic, 263. terebic, 384. terephthalic, 357. terpenylic, 384. tetraboric, 124. tetrathionic, 89. thioacetic, 287. thiobenzoic, 365. thiocarbamic, 316. thiocyanic, 308. thiosulphtiric, 92. trichloracetic, 253. trichromic, 131. tricyanic, 307. trihydrocyanic, 310. trinitrophenic, 369. trithionic, 89. uric, 406. uroleucic, 359. urous, 410. valerianic, 254. valeric, 254. vanillic, 354. xanthic, 410. Acids, 36, 39 (see Acid), acetic series, 250. alcohol, 259. aldehyde, 265. alkyl benzoic, 356. amic, 310, 313. amido, 321. butyric, 325. caproic, 325. cinnamic, 374. phenyl, 373, 374. propionic, 325. valeric, 325. anil, 376. anilic, 375. anilido, 374, 375. aromatic amido, 373. carboxylic, 355. dioxycarboxylic, 358. monocarboxylic,, 355. polycarboxylic, 356. trioxycarboxylic, 359. atomicity of, 259. basicity of, 36, 259. 454 INDEX Acids, ben/me dicarboxylic, 357. disulphonic, .'(>. benzole series, 355. camphoric, 384. caproic, 254. carbopyridic, .'5!) 7. carboxylic, 250. cresylic, 347. dibasic, 30. dicarboxylic, 265. dioxydicarboxylic, 264. dioxyethylene succinic, 264. dioxymonocarboxylic, 358. dioxyphenyl, 359. dioxytoluic, 359. fatty, 250. hexan, 254. hexylic, 254. hydroaromatic, 383, 384. hydrophthalic, 357. hydroxamic, 300, 301, 376. indolecarboxylic, 415. ketonic, 266. lactic, 262. mannosaccharic, 265. mineral, 77. monamido, 321. monobasic, 36. monocarboxylic aromatic, 3f>.~>. monoketone monocarboxylic, 266. monoxydicarboxylic, 20.'!. monoxymonocarboxylic, 357. naphthol sulphonic, 387. nitro, 321, 370. nitrobenzenic, 370. nitrobon/oic, 370. of antimony, 122. arsenic, 113. nitrogen, 100. phosphorus, 107. sulphur, 89. olefinedicarboxylic, 332. oleic, 331. ortho, 108. oxalic series, 256. oxyacetic, 260. oxyaldehyde, 266. oxybenzoic, 357. oxybutyric, 263. oxyketone, 266. oxypropionic, 262. oxytricarlioxylic. 265. paraffin dirarboxylio, 256. monocarboxylic, 250. pentan, 254. phenol carlioxylic. 357. phenyl amido, : ) .73, 374. bitty, .",.-><.. propionic, 35(i. plithaiic. :::.;. polyliasic. .",0. pyrrolidmcarboxylic, 393. radical of, -10. Acids, residue of, 46. saccharic, 265. sulphinic, 277, 286, 366. sulplionic, 277, 284, 286, 365. sulphurous, 89. tannic, 360. tartaric, 2:5!), 264. tetro.xydicarbo.x yl ic, 205. thiocarbamic, 310. thiosulphonic, 2SO. tolueni'sul phonic, :>00. tribasic, :>0. trioxymonocarboiylic, 359. valerianic, 254. valeric, 254. volatile fatty, 250. Acidulous elements, 52, 73. Ac-idyl halidcs, 270. hydroxides, 250. Acidylenes, 256. Aconine, 440. Aconite alkaloids, 440. Aconitine, 440. Acroleine, 330. Acrose, 240. Acyclic compounds, 199, 201. Acylation, 284. Addition, 197. Adenine, 412. Adipocere, 444. Adjacent positions, 338. Adonite, 225. JCsculetin, 362. JEsculin, 362. Affinity, 48. After-damp, 204. Air, See Atmospheric air. Alabaster, 109. Alanine, 375. Alanines, 322, 325, 375. Albite, 180. Alcohol, 214, 217 (see Alcohols). absolute. 215, 217. acids, 259. allyl, 330. am'idoethyl, 319. amylic, 220. benzyl ic, 352. butylic, 220. debydratum, 217. denatured, 218. dilutum, 217. cslcvs. 275. ctliylcnc, 222. ethylic, 214. isobutylic, 220. methylic, 214. nitrocl hylic. 319. oxylicii/ylic, 352. propenyl, 223. t ropan. 1'2.'>. vinyl, 214. wood. 214. INDEX 455 Alcoholates, 213. Alcohol!^ beverages, 218. fermentation 215, 218. Alcohols, 210. amido, 319. amylic, 220. aromatic, 351. butyl, 220. camphan, 383. cinnamic, 352. diatomic, 221, 352. dihydric, 221, 352. diphenyl, 380. heptatomic, 225. hexatomic, 225. hexahydric, 225. hydroaromatic, 382. iso, 211. menthan, 383. monoatomic, 211. monohydric, 211. nomenclature of, 211, 221. nonatomic, 225. octatomic, 225. oxyplienyl, 352. pentatomic, 225. pentahydric, 225. polyatomic, 224. polyhydric, 224. primary, 211, 212, 213. propyl,' 219. ring, 382. secondary, 211, 212, 214, 352. tertiary,' 211, 212, 214, 352. tetratomic, 225. tetrahydric, 225. triatomic, 223, 352. trihydric, 223, 352. Aldehyde, acetic, 229. acids, 2G5. acrylic, 330. ammonia, 227, 230, 296, 319. anisic, 354. benzoic, 353. formic, 228. glyceric, 237. glycolyl, 237. hydrazones, 321. methylprotocatechuic, 354. salicylic, 354. Aldehydes, 225, 226. aromatic. 353. define, 330. Aldehydrazones, 380. Aldoses, 236. Aldoximes, 320. Ale, 218. Algaroth, powder of, 121. Aliphatic compounds, 199, 201. unsaturated, 327. Alizarin, 388. Alkali, 149. carbonated, 149. Alkali, caustic, 149. metals, 149. volatile, 95, 149. Alkaline earths, metals of, 168. reaction, 33. Alkaloids, 419. aconite, 440. cinchona, 428. classification of, 421. general reactions of, 421. isoquinoline, 421, 433. loganiacese, 431, nomenclature of, 420. opium, 434, 437. phenanthrene, 422, 433. piperideine, 421. piperidine, 421, 422. properties of, 420. pyridine, 421. pyrrolidine, 421. piperidine, 421, 424. pyridine, 421, 423. quinoline, 421, 429. strychnos, 431. tropan, 421, 424. Alkanes, 202. Alkaptonuria, 359. Alkarsin, 326. Alkyl, 202. 'halides, 205. hydroxides, 211. pyridines, 398. pyridinum iodides, 397. ureas, 316. Alkylation, 284. Alkylenes, 221. Allantoin, 395. Allene, 330. Allometa position, 339. Allortho position, 339. Allotropy, 9. Alloxan, 405. Alloxantin, 404. Alloxuric bases, 409. Alloys, 185. Allyl alcohol, 330. amine, 333. isothiocyanate, 333. oxide, 333. sulphide, 333. Allylene, 330. Alphenols, 352. Alumina, 178. Aluminates, 178. Aluminium, 178. bronze, 178. chloride, 179. group, 177. hydroxide, 178. oxide, 178. silicates, 180. sulphates, 179. Alums, 179. 456 INDEX Amalgams, 185. Amanitine, 21)0. Amide nitrogen, 293. Amidines, 300. Amido acetaldehyde, 319. acetones, 319. acids, 321. aromatic, 367. alcohols, 319. aldehydes, 311). azo compounds, 379. benzenes, 371. benzol, 371. group, 293. ketodihydropyrimidine, 403. ketones, 319. ketopurine, 411. paraffins, 292. phenyl acids, 367. phenylalanine, 375. phenols, 373. purine, 412. xylenes, 372. Amidoximes, 300, 376. Amides, 310 (see Monamides, Dia- mides). aromatic, 367, 373. mixed, 310. of dicarboxylic acids, 313. Amine bases, 292. nitrogen, 293. Amines, 292 (see Monamines, Dia- mines.) aromatic, 367. Ami no group, 293. Ammelide, 315. Ammonia, 95. aldehyde, 227, 230, 296, 319. bismuth of, 167. caustic, 166. Ammonias, compound, 293. Ammonio-magnosium phosphate, 174. Ammonium, 96, 165. acetate, 167. alum, 179. amalgam, 166. bromide, 167. carbonates, 167. chloride, 96, 166. compounds, 165. cyanate, 307. derivatives. 292. hydroxide, 96, 106. iodide, 167. nitrate, 167. sesquicarbonate, 167. sulphates, 167. sulplmlrate, 166. sulphides, 166. theory, 105. Amorphous substances, 4. Ampere, 21. Amphoteric elements. 53, 129. Amphoteric reaction, 33. Amygdalin, 303, 362. Amyl nitrate, 279. nitrite, 279. Amylene, 330. hydrate, 221. Amylum, 245. Analysis, 33, 63. organic, 194. Analytical characters of alcohol, 218. aluminium, 180. ammonia, 96. ammonium, 167. aniline, 371. antimony, 123. arseni?, 116. atropine, 426. barium, 172. bismuth, 144. bromidion, 81. brucine, 433. cadmium, 177. calcium, 171. carbolic acid, 346. carbon dioxide, 274. chloridion, 78. chloroform, 206. chromium, 131. cobalt, 181. cocaine, 428. conime, 422. copper, 183. cyanides, 304. fluorine, 74. formaldehyde, 229. glycerol, 224. gold, 130. hydrogen, 59. dioxide, 70. sulphide, 87. iodidion, 83. iron, 137. lead, 141. lithium, 150. magnesium, 175. manganese, 132. mercury, 189. morphine, 435. nickel, 181. nicotine, 424. nitrates, 102. nitrobenzene, 368. oxalates, 258. oxygen, 61. ozone, 62 phenol, 346. phosphates. 109. phosphorus, 106. potassium, 163. quinine, 429. silver, 105. sodium, 156. strontium, 171. INDEX 457 Analytical characters of strychnine, 432. sulphates, 92. sulphides, 87. sulphites, 89. sulphur dioxide, 88. tin, 146. zinc, 177. Anethol, 354. Anglesite, 138. Anhydride, acetic, 269. antimonic, 122. antimonous, 121. arsenic, 113. arsenous, 112. benzoic, 364. boric, 124. carbonic, 272. chromic, 130. hypochlorous, 79. molybdic, 128. nitric, 100. nitrous, 99. phosphoric, 107. phosphorous, 107. phthalic, 364. plumbic, 139. salicylic, 364. silicic, 127. succinic, 259. sulphuric, 88. sulphurous, 87. titanic, 145. tungstic, 128. Anhydrides, 46, 61. 'acid, 269. aromatic, 364. halide, 270. thio, 87. Anhydroecgonine, 427. Anilido acids, 374, 375. Anilides, 372. Aniline, 371. dyes, 373, 376. Anions, 20, 35, 45. Anisidines, 369, 372. Anisol, 360. Annidalin, 348. Anode, 19. Anthracene, 386. oil, 341. Anthracite, 125. Antifebrine, 372. Antimony, 120. acids of, 122. black, 122. butter of, 121. chlorides of, 121. crocus of, 122. crude, 122. glass of, 122. liver of, 122. organic compounds of, 326. oxides of, 121. Antimony, pentachloride, 121. pentasulphide, 122. pentoxide, 122. sulphides of, 122. tartrated, 162. trichloride, 121. trioxide, 121. trisulphide, 122. Antimony 1 potassium tartrate, 162. Antipyrine, 394. salicylate, 394. Antiseptics, 444. Apoatropine, 427. Apomorphine, 434, 436. Apoquinine, 430. Aqua ammoniae, 96. destillata, 67. fortis, 101. regia, 77, 102. sapphirina, 183. Arabin, 246. Arabinose, 237. ArecaTne, 422. Argol, 161. Argon, 72. Aricine, 429. Aristol, 348. Aromatic compounds, 200, 334, 336. Arragonite, 170. Arsenates, 115. Arsenic, 110, 112, 115. antidote, 115. bisulphide, 114. halides, 112. organic compounds of, 326. pentasulphide, 114. pentoxide, 113. trichloride, 112. triiodide, 112. trioxide, 112, 115. trisulphide, 114. Arsenical greens, 115. Arsenites, 113. Arsine, 111. dimethyl, 326. Arsines, 326. Artesian wells, 65. Artiads, 30. Asbestos, 173. Aselline, 282. Aseptol, 366. Asymmetric carbon atom, 329. Atmospheres, 4. Atmospheric air, 72, 94. ammoniacal compounds in, 95. analysis of, 274. carbon dioxide in, 95, 272, 274. nitrous acid in, 95. rare elements in, 72. solid particles in, 95. sulphurous acid in, 95. water in, 95. Atom, 25, 26. 458 INDEX Atomic rearrangement, 33. theory, 24. weight, 26. Atomicity, 30, 37. Atropamine, 427. Atropine, \-~>. Auric chloride, 129. Aurin, 350. Auroamidoimide, 308. Aurous chloride, 129. Avogadro, postulate of, 24. Azines, 398. Azobenzene, 378, 379. Azo compounds, 367, 376, 378. dyes, 376. Azoimide, 97. Azoles, 393. Azonaphthol compounds, 387. Azo nitrogen, 293. Azote, 94. Azoxy benzene, 378. Azoxy compounds, 378. Baking powders, 161. Balsams, 385. Barium, 171. carbonate, 172. chloride, 172. dioxide, 172. hydroxide, 172. monoxide, 171. nitrate, 172. oxides, 171. sulphate, 172. Baryta water, 171, 172. Bases, 36, 39. acidity of, 37. atomicity of, 37. Bassorin, 246. Basylous elements, 53, 149. Battery, galvanic, 19. Bauxite, 178. Beer, 218. Belladonnine, 427. Benzamide, 356, 373. Benzeno, 334, 341. amido, 371. amido derivatives of, 367, 371. azomethane, 378. azoxy, 378. halides, 343. homologues of, 341. hydroxylamine derivatives of, 367, 370. imido derivatives of, 367. nitro, 367. nitro derivatives of, 367. nitrogen derivat ives of, 367. nitroso derivat i\ TS of, 367. nucleus, 334. oxygen compounds of, 343. sulphoehloride, 366. Benzenyl, 356. amidine, 356. amidoxime, 376. Benzhydrol, :$S9. Benzidine, 371). Benzine, 20}. Benzol, 341. Benzolene, 204. Benzonitrile, 373. Benzophenol, 345. Benzopyridine, 414. bases, 418. Benzopyrrole, 415. Benzoquinone, 351. Benzosol, 349. Benzosulphinide, 366. Benzoyl, 343. amide, 373. chloride, 364. ecgonine, 427. glycocoll, 375. hydride, 353. morphine, 434. sulphonic imide, 366. Benzyl, 343. benzene, 388. chloride, 343. hydrate, 352. Betaine, 298. trimethylacetic, 298. Betames, 207. Beverages, alcoholic, 218. Bieberich scarlet, 387. Bilineurin, 296. Bismark brown, 101. Bismuth, 142. hydroxide, 143. magma of, 143. milk of, 143. nitrate, 143. of ammonia, 167. oxides of, 143. subcarbonate, 143. subnitrate, 143. trichloride, 143. trinitrate, 143. trioxide, 143. Bismuthates, 142. Bismuthyl, 142. carbonate, 143. chloride, 143. hydroxide, 143. nitrate, 143. Biuret, 315, 317. Black wash, lSf>. Illraehing powder, 169. Blende, 17.">. Ulue stone, 183. Boiling, lf>. Hi. point. 12, 16. absolute, 16. Bone ash, 170. Maek, 1-JU. INDEX 459 Bone oil, 397. phosphate, 170. Borax, 154, 214. Bordeaux dyes, 387. Borneo camphor, 383. Borneol, 383. Boroglyceride, 124. Boron, 123. trioxide, 124. Braunite, 131. Brimstone, 84. British gum, 246. Bromamide, 312. Bromidion, 81. Bromides, 80. Bromine, 80. Bromoform, 207. Bromophenols, 348. Brucine, 433. Butalanine, 325. Butyl morphine, 434. Butyrolactam, 393. Cacodyl, 326. cyanide, 327. oxide, 326. Cadaverine, 299. Cadet, liquid of, 326. Cadmium, 177. Caesium, 163. Caffeine, 411. Calamine, 176. Calcium, 168. acetylide, 329. carbide, 169. carbonate, 170. chloride, 169. group, 168. hydrate, 169. hydroxide, 169. hypochlorite, 169. oxalate, 170. oxide, 168. phosphates, 170. plumbite, 139. sulphate, 169. Calcspar, 170. Calomel, 186. Calorie, 12. Camphan alcohols, 383. Camphol, 383. Camphor, 384. Borneo, 383. Japan, 384. laurel, 384. monobromo, 384. Camphors, 384. Camphoryl morphine, 434. Campobello, yellow, 387. Cane sugar, 242. Caramel, 243. Carbamide, 314. Carbamines, 306. Carbides, 329. Carbimide, 318. Carbinol, 211, 214. butyl, 220. diethyl, 221. diphenyl, 389. diphenyltoluyl, 389. ethyl, 219. ethyldimethyl, 221. ethylmethyl^ 220. isobutyl, 220. isopropyl, 220. methyl, 214. methylisopropyl, 221. methylpropyl, 221. phenyldimethyl, 352. phenylmethyl, 352. propyl, 220. trimethyl, 220. triphenyl, 389. Carbocyclic compounds, 200, 334, 335. Carbodiimides, 372. Carbohydrates, 235. tests for, 247. Carbolates, 346. Carbolic oil, 341. Carbo animalis, 126. ligni, 125. Carbon, 124. amorphous, 125. compounds of, 191. dichloride, 207. dioxide, 272. disulphide, 287. group 124. metallic, 125. monoxide, 270. hemoglobin, 271, 273. oxides of, 270. oxysulphide, 288. tetrabromide, 207. tetrachloride, 207. trichloride, 207, 280. valence of, 196. Carbonic acid gas, 272. Carbonic anhydride, 272. oxide, 270. Carbonous oxide, 270. Carbonyl, 198. chloride, 271. diurea, 318. Carborundum, 127. Carbotriamine, 301. Carboxime, 320. Carboxyl, 198. Carbylamines, 295, 306. Carbyloxime, 307. Carn'allite, 157. Carnine, 409, 413. Carvacrol, 348. Carvol, 348. Cassel yellow, 140. Cassiterite, 145, 146. 460 INDEX Cassius' purple, 129. ( 'atalysers, .IS. Cathode, 19. Cations, 20, 35, 45. Celestine, 171. Cellulin, 247. CVlluloid, 247. Cellulose, 247. nitro, 247. Celsius' scale, 12. Centigrade scale, 12. Cerebrin, 241. Cerebrose, 241. Ceruse, 141. Cerusite, 141. Cetaceum, 279. Cetin, 279. Cetyl palmitate, 279. Chains, 199, 200. Chalk, 170. precipitated, 170. prepared, 170. Characterizing groups, 198. Charcoal, 125. animal, 126. wood, 125. Chelidonine, 397. Chemical affinity, 48. change, 1. displacement, 48. energy, 48. equilibrium, 49. equivalent, 31. force, 48. stability, 48. system, 49. Chemism, 48. Chemistry, 1. general, 1. inorganic, 57. organic, 191, 192. Chinovose, 237. Chloral, 230, 231. alcholate, 232. hydrate, 231. Chloralamide, 312. Chloraldide, 232. Chloralide, 232. Chloralimide, 312. Chloralum, 170. Chloride of lime, 169. Chloridion, 78. Chlorides, 78. Chlorinated lime, 169. Chlorine, 74. group, 73. monoxide, 79. peroxide, 79. tetroxide, 79. water. 7"). Chloroben/.cnes, 343. Chloroform. 2 INDEX 461 Condensed heterocyclic compounds, 414. nuclei, 385. Condensing agents, 229. Conductors, 17. Condy's fluid, 155. Congelation, 15. Conhydrine, 422. Coniferin, 354, 362. Coniceme, 422. Coniiine, 398, 422. Consecutive positions, 338. Constitution, 46, 193, 196. Contact agent, 268. Copper, 181. acetates, 183. acetylide, 329. ammonio-sulphate, 183. chlorides, 182. group, 181. hydroxides, 182. oxides, 182. reduction tests, 248. Copperas, 135. Coprolites, 170. Corallin, 350. Cordials, 219. Corrosive sublimate, 187. Corrosives, 78, and see Toxicology. Corundum, 178. Cosmoline, 204. Cotarnine, 436, 438. Coulomb, 21. Cream of tartar, 161. Creasol, 347. Creosote, 347. oil, 341. Creatine, 302. Creatinine, 302. Creolin, 347. Cresols, 347. Cresylols, 347. Crith, 58. Cryolyte, 73, 178. Crystallization, 4. water of, 8, 63, 64. Crystalloids, 9. Crystals, 5. Cupric acetate, 183. arsenite, 183. chloride, 182. hydroxide, 182. nitrate, 182. oxide, 182. sulphate, 183. Cuprous chloride, 182. hydroxide, 182. oxide, 182. Curarine, 433. Cyamelide, 307. Cyanamide, 309. Cyanidine, 414. Cyanides, 303, 305. Cyanobenzene, 373. Cyanogen, 303. chlorides, 304. compounds, 303. hydride, 303. sulphydrate, 308. Cyclic compounds, 200, 334. Cyclodiolefine, 335. Cyclohexane, 335. Cycloparamns, 335. Cyclotriolefine, 335. Cymene, 342. Cymogene, 204. Cytosine, 403. Daphnetin, 362. Daphnin, 362. Deamidation, 323. Decompositions, 33. double, 33, 37. primary, 34. Defuselation, 220. Dehydromorphine, 434. Deliquescence, 15, 16. Density absolute, 3. relative, 3. Deodorizers, 444. Deoxidation, 58. Deoxystrychnine, 432. Derived substances, 208. Dextrin, 246. Dextrose, 240. Diabetic sugar, 240. Diacetine, 223. Diacetonamine, 319. Diacetylene series, 201. Diacetylethylenediamine, 298. Diacetylmorphine, 434. Diachylon, 139. Dialdehydes, 233. Dialysis, 9. Diamide, 96. Diamides, 310. primary, 314. Diamidodiphenol, 379. Diamine diacetylethylene, 299. diethylene, 400. ethylene, 299. pentamethylene, 299. phenylene, 380. tetramethylene, 299. trimethylene, 299. Diamines, 292, 296, 298. Diamond, 125. Diastase, 214. Diazines, 399. Diazo, amido compounds, 367. benzene chloride, 376. compounds, 376. dyes, 379. nitrogen, 293. Diazoles, 393, 394. Diazotizing, 377. 462 INDEX Dibromomethyl bromide, 207. Dicacodyl, 326. Dichlormethane, 206. Dichlorincthyl chloride, 206. Dievanogen, .'!07. Diethylcarbinol, 221. Diethylenediamine, 400. Diethylmalonylurea, 404. Diethyl sulphite,, 277. Diffusion of liquids, 9. Diglycerides, 223, 280. Digital iresin, 363. Digitalis glucosides, 363. Digitalin, 363. Digitalose, 363. Digitogenin, 363. DigitoneTn, 363. Digitonin, 363. Digitoxin, 363. Dihydrobenzenes, 335. Dihydrofurfurane, 392. Dihydropyridines, 398. Dihydropyrrole, 393. Dihydrostrychnoline, 432. Diimines, 296. Diindoxyl, 418. Diiodomethyl iodide, 207. Diketones, 233, 235, 354. Diketopurine, 410. Diketotetrahydroglyoxalin, 395. Diketotetrahydropyr imidine, 401 . Dimethyl aniine, 295. arsine, 326. benzenes, 342. iodoles, 415. ketone, 234. malonylurea, 404. pyrazolon, 395. pyridines, 398. Dimorphism, 8. Dinitrobenzenes, 368. Dinitronaphthols, 387. Dinitrophenols, 369. Dinitrosoresorcinol, 370. Diolefines, 201, 330. Diols, 221. Dionine, 434. Dioses, 236, 237. Dioxindole, 374. Dioxyacetone, 237. Dioxyanthraquinone, 388. Dioxymet liylanthraquinone, 388. Dioxypurine, 410. Diphenyl, 388. acetylene, 388. benzene, 388. Diplienyleiic (1 iket one , .387. Diphenyl ethylene, IIS!). hydra/ine, :J7'.>. methane, oleftnee, oxide, .".tilt, parall'ms. Disaccharides, 236, 241. Disacryl, 331. Disdia/oamido compounds, 377, 3*78. Disinfectants, 444. Displacement, 48. Dissociation, 35, 64. Distillation, 16, 67. fractional, 16. Diureides, 317. Divisibility, 2. Dolomite, 174. Dulcin, 225. Dulcitan, 225. Dulcite, 225. Dulcitol, 225. Dulcose, 225. Dutch liquid, 280, 328. Dyads, 30, 31. Ebullition, 15. Ecboline, 441. Ecgonine, 398, 427. Efflorescence, 9. Elayl, 327. chloride, 280. Electric circuit, 19. conductance, 20. conductivity, 20. current, 19. resistance, 20. units, 21. Electricity, 17. galvanic, 18. negative, 17. positive, 17. resinous, 17. vitreous, 17. Electrodes, 10. Electrochemical series, 33, 34. Electrolysis, 20, 33. Electrolyte, 20. Electromotive force, 20. Electronegative, 33, 34. Electropositive, 33, 34. Elements, 21, 27. acidulous, 52, 73. amphoteric, 53, 129. basylous, 53, 149. classification of, 51. electronegative. :;::. ::i. 52. electropositive. :;:;. :\\, 53. equivalence of, 30. in earth's crust, 21. in human body, 21, 22. typical, 52, 57. which form no compounds, .VJ, 7'2. Elutriat ion, 170. Emerald, 178. Kmery, ITS. Minet ine, 4-1 1 . Kinulsifying agents, 282. Emulgin, ::;i. Knuilsion, 282. INDEX 463 Energy, 3. chemical, 48. kinetic, 3. potential, 3. Enzymes, 216. Eosin, 350. Epiguanine, 413. Episarkine, 409, 413. Epsom salt, 173. Equations, 32. Equilibrium, apparent, 50. chemical, 49. dynamic, 49. heterogeneous, 49, homogeneous, 49. real, 49. Equivalence, 30. Equivalent, 37. chemical, 31. osmotic, 9. Ergotine, 441. Erythrin, 224. Erythrite, 224. Erythrodextrin, 246. Erythrol, 224. Erythrose, 237. Eserine, 441. Essence of Mirbane, 367. of turpentine, 382. Essences, 282. Ester, acetoacetic, 278. malonic, 279. methylenemalonic, 332. sulphates, 367. Esters, 267, 275. alcohol, 275. dioxymalonic, 266. haloid, 205, 279. hyposulphurous, 277. isothiocyanic, 80S. of carbamic acid, 313. of dihydric alcohols, 279. of glycerol, 280. of glycols, 279. of monohydric alcohols, 276. of oxyacids, 283. of trihydric alcohols, 280. orthoformic, 277. oxymalonic, 266. thiophosphoric, 285. sulphurous, 277. Ethanal, 229. Ethene, 327. chlorhydrine, 222. compounds, 328. glycol, 222. homologues of, 328. series, 327. Ethenylamidoxime, 300. Ether, acetic, 278. allylic, 333. dimethylpyrocatechuic, 349. ethyl ic, 268. Ether, ethylphenyl, 361. hydriodic, 208. hydrobromic, 208. hydrochloric, 208. methylphenyl, 360. monomethylpyrocatechuic, 349. muriatic, 208. nitric, 276. nitrous, 276. ozonic, 70. petroleum, 204. phenyl, 360. propargylethyl, 333. sulphuric, 268, 277. Ethers, 267. compound, 267, 275. haloid, 205. mixed, 267. phenyl, 360. simple, 209, 267. Ethidene chloride, 328. compounds, 328. hydroxamine, 319. hydroxylamine, 296. Ethine, 329. Ethol, 279. Ethyl acetate, 278. acetoacetate, 278. benzene, 342. borate, 124. bromide, 208. carbinol, 219. chloride, 208. dimethylcarbinol, 221. hydroxide, 214. iodide, 208. malonate, 279. mercaptan, 285. methylcarbinol, 220. morphine, 434. nitrate, 276. nitrite, 276. oxide, 268. pyridines, 398. strychnium iodide, 432. sulphate, 277. sulphydrate, 285. urethane, 313. Ethylene, 327. alcohol, 222. chlorhydrine, 279. chloride, 280, 328. compounds, 328. diamine, 299. ethenyl amidene, 299. glycol, 222. hydroxide, 222. oxide, 269. Ethylidene compounds, 328. Eucalypteol, 383. Eucalyptol, 383. Euphorine, 314. 464 INDEX Evaporation, 15. Exalgine, 372. Fahrenheit's scale, 12. Farad, 21. Fats, 282. phosphorized, 282. Fatty compounds, 199, 201. Feldspar, 178, 180. Fermentation, 215. acetic, 215, 252. butyric, 216, 253. lactic, 216, 262. test, 249. Ferments, false, 216. true, 215. Ferric acetates, 136. chloride, 135. citrate, 136. ferrocyanide, 136. hydroxide, 134. with magnesium oxide, 115. oxide, 134. phosphate, 136. sulphates, 135. sulphide, 135. Ferroso-ferric oxide, 134. Ferrous acetate, 136. bicarbonate, 136. carbonate, 136. chloride, 135. ferricyanide, 137. hydroxide, 134. oxide, 134. . phosphates, 136. sulphate, 135. sulphide, 134. Ferrum reductum, 133. Filtration, 67. Fire-damp, 203. Flavaniline, 372. Flowers, 17. Fluorene, 385. Fluoresceine, 349, 350. Fluorine, 73. Fluor spar, 73. Flux, black, 160. Force, 1. chemical, 48. electromotive, 2Q. Formal, 233. Formaldehyde, 228. Formaline, 228. Formals, 232. Formamide, 312. Formin, 311). Kormunifrile, 303, 305. Formose, 229, 240. Formula^, 32. algebraic, 1113. empirical, :{-J. general, !!>:!. graphic, 47, 193. Formulae, rational, 46. typical, 47. Fossil resins, 385. wax, 204. Fowler's solution, 115. Freezing point, 11, 15. Fructose, 241. Fruit sugar, 241. Fucose, 237. Function, 36. Furazoles, 393. Furfural, 392. Furfuraldehyde, 392. Furfurane, 392. Furfurole, 392. reaction, 247. Furole, 392. Fusel oil, 220. Fusing point, 14. Fusion, 13. latent heat of, 14. Gadinin, 282. Galactose, 241. Galena, 138, 140. Gallisin, 240, 244. Gallium, 177. Galvanic battery, 19. cell, 19. circuit, 19. electricity, 18. Garnet, 178. Gas, carbonic acid, 272. laughing, 97. tar, 341. Gases, 4, 10, 15. absorption of, 11. Gasoline, 204. Gelatin, explosive, 247. sugar, 323. Geneva convention, 199. Germicides, 444. Glass of antimony, 122. soluble, 153. water, 153. Glauber's salt, 153. Glonoin, 280. Glucinium, 177. Glucosazone, 381. Glucose, 240. Glucoses, 237. Glucosides, 361. Glucosyl phenate, 361. Glucovanillin, 362. Glycorides, 280. (Jly.-erine, 223. Glycerites, 224. Glycerol, 223. eaters of organic acids, 281, halohydrines, 280. ketone, 237. tri nitrate, 280. Uv.vrols, 222, 224. INDEX 465 Glycine, 323. Glycogen, 245. Glycocoll, 323. trimethyl, 298. Glycocolls, 322. Glycol ethene, 222. ethylene, 222. halohydrines, 279. monothioethylene, 286. tetramethylethylene, 222. Glycols, 221. xylylene, 352. Glycolyl aldehyde, 237. urea, 395. Glyoxal, 233, 262. Glyoxaline, 396. Glyoxyldiureide, 395. Gold, 129. fulminating, 308. trichloride, 129. Goulard's extract, 141.' Gram, calorie, 12. equivalent, 31, 37. molecule, 29. Granulose, 245. Grape sugar, 240. Graphite, 125. Gravity, specific, 3. Grignard's compounds, 290. reactions, 290. Groups, characterizing, 198. Guaiacol, 347, 349. Guanidine, 301. Guanidines, substituted, 301. Guanides, 405. Guanine, 411. Guaranine, 411. Gum resins, 385. Gums, 246. Gun cotton, 247. powder, 158. Guvacine, 422. Gypsum, 169. Halide anhydrides, 270. Halides, acidyl, 270. Halogens, 73. Hausmannite, 131. Heat, 11. changes in volume caused by, 12. effects of, 11. latent, 14. of fusion, 14. of vapor, 16. measure of, 12. quantity of, 11. specific, 17. units of, 62. Heavy spar, 172. Helium, 72. Hematin, 273. Hematite, 132. Hematoporphyrin, 273. Hemiterpenes, 382. Hemochromogen, 273. Hemoglobin, 273. Heptoses, 236. Heroine, 434. Heterocyclic compounds, 200, 334, 389, 414. Heteroxanthine, 410. Hexacarbocyclic compounds, 336. Hexadiene, 335. Hexads, 30, 31. Hexahydrobenzene, 335, 381. Hexahydrocymene, 382. Hexahydropyrazine, 400. Hexahydropyridine, 398. Hexamethylene, 335. tetramine, 319. Hexatriene, 335. Hexene, 335. Hexites, 225. Hexoses, 236, 237. Histidin, 396. Homatropine, 427. Homologous series, 193. Horn lead, 138. Hydantoin, 317, 395. Hydracetine, 381. Hydracids, 36. Hydramines, 296, 319. Hydrargyrum, 184. Hydrates, 64. Hydrazidos, 302, 303. Hydrazine, 96. compounds, 379. Hydrazines, 302, 379. aromatic, 379. Hydrazobenzene, 378, 379. Hydrazo compounds, 378. nitrogen, 293. Hydrazones, 377. aldehyde, 321. ketone, 321. Hydrion, 35. Hydroaromatic compounds, 381. Hydrocarbons, 194, 201, 202. acetylene series, 201, 329. aliphatic, 201. condensed, 386. diacetylene, 201. diolefine, 330. ethene series, 327. hydroaromatic, 381. methane series, 201. monobenzenic, 341. olefine series, 327. saturated, 201. Hydrocotarnine, 436, 438. Hydrogen, 57. antimonide, 121. arsenide, 111, 115. bromide, 80. chloride, 76. cyanide, 303. 466 INDEX Hydrogen, dioxide, 69. fluoride, 73. iodide, 82. nitride, 95. peroxide, 69. phosphides, 106. sulphide, 85. sulphuretted, 85. Hydrolysis, 33, (.4. Hydroimphthulenes, 386. Hydropyridines, 398. Hydropyrimidines, 398. Hydropyrroles, 393. Hydroquinone, 349. Hydrosulphides, 87. Hydroterpenes, 382. Hydrouracil, 401. Hydroxamines, 296, 319. Hydroxidion, 35. Hydroxides, 37, 64. alkyl, 211. basic, 64. hydrocarbon, 210. Hydroxyl, 37. determination of, 284. Hydroxylamine, 97. compounds, 292. aromatic, 370. Hyoscine, 427. Hyoscyamine, 426. Hypnone, 355. Hypophosphites, 108. Hypoxanthine, 411. Iceland spar, 170. Ichthyol, 287. Imide nitrogen, 293. Imido group, 293. Imidoparaffins, 293. Imides, 310, 313, 318. Imine bases, 292. Imine nitrogen, 293. Imines, 296, 313. Imino group, 293. Impenetrability, 2. Indene, 385. Indestructibility, 2. Indican, 363. urinary, 417. Indicanin, 363. Tmliglucin, 363. Indigo blue, 417. white, 418. Indigotine, 417. Indium, 177. Indole, 415. homologues, 415. Indoxyl, 41 (i. Induline dyes, 379. Indulinr, 241, 2 Hi. lii'-i-lia, 2. I in. site, :W2. Insulators, 17. Inulin, 241, 246. Inversion, 241. Invert in, 361. lodidion, 83. Iodides, 82. Iodine, 81. chlorides of, 83. number, HiibPs, 332. oxyacids of, 82. lodoform, 207. lodophenols, 348. lodoquinine sulphate, 429. lonization, 35. Ions, 17, 35. Iridium, 147. Iron, 132. acetates of, 136. chlorides of, 135. citrates of, 136. dialysed, 134. galvanized, 133. group, 130. hydroxides of, 134. magnetic oxide of, 134. oxides of, 134. phosphates of, 136. reduced, 133. spathic, 136. sulphates of, 135. sulphides of, 134. Ironstone, 132. Isatine, 417. Isoacetonitrile, 306. Isobenzonitrile, 306, 373. Isocholine, 296. Iso compounds, 202. Isocyanates, 307. Isocyanides, 295, 306. Isodipyridine, 424. Isodulcite, 237. Isoindole, 416. Isoleucine, 325. Isomaltose, 240, 244. Isomeres, optical, 239. Isomerism, 194, 337. place, 260, 337. position, 260. space, 238. stereo, 238. Isomorphism, s. Isonitriles, 295. Isopropyl carbinol, 220. Isoquinoline, 419. alkaloids, 421, 433. Ivory black, 126. Jaborandine, 428. Jaborine, 428. Japaconine, 440. -Japaronit inr, 440. lavellc \vatrr, 158. Jervine, 441. INDEX 467 Kaolin, 180. Kathod^, 19. Rations, 20, 35, 45. Kelp, 81. Kerrttes mineral, 122. Kerosene, 204. Ketohydrazones, 380. Ketone acids, 266. dimethyl, 234. glycerol, 237. hydrazones, 321. phenylmethyl, 355. Ketones, 225, 233. aromatic, 354. hydroaromatic, 383. Ketopiperazines, 323. Ketopurines, 411. Ketoses, 236. Ketoximes, 320. Kilowatt, 41. King's yellow, 114. Knock-out-drops, 232. Krypton, 72. Labarraque's solution, 154. Labile substances, 49. Labradorite, 180. Lacmoid, 349. Lactam, methyl guanidinacetic, 302. Lactams, 323. Lactides, 261, 283. Lactones, 261, 283. Lactose, 244. Lampblack, 126. Lapis infernalis, 165. Laughing gas, 97. Law or laws, Boyle-Mariotte, 10. Dalton-Gay Lussac, 13. of Ampere, 24. of Avogadro, 24. of Charles, 13. of definite proportions, 22. of Gay-Lussac, 24. of Graham, 58. of Henry, 11. of multiple proportions, 23. of reciprocal proportions, 23. Ohm's, 20. periodic, 54, 55. Lead, 138. acetates, 140. black, 125. carbonate, 141. chamber crystals, 99. chloride, 140. chromate, 140. dioxide, 139. group, 138. iodide, 140. monoxide, 139. nitrates, 140. oleate, 139. oxides, 139. Lead, oxychlorides, 140. red, 139. salts of, 140. subacetate, 14L sugar of, 140. sulphate, 140. sulphide, 140. white, 141. Leads, electric, 19. Lecithins, 282. Lethol, 279. Leucine, 325. Leucines, 325. Leucomames, 442. Leucopararosaniline, 389. Levigation, 170. Levulose, 241. Lichenin, 246. Light, chemical effects of, 51. Lignin, 247. Lime, 168. chlorinated, 169. chloride of, 169. milk of, 169. quick, 168. slaked, 169. water, 169. Limestone, 170. Linkages, 196. Liquefaction, 16. Liqueurs, 219. Liquids, 4, 14, 15. diffusion of, 9. Liquor ammonii acetatis, 167. calcis, 169. chlori compositus, 75. hydrogenii dioxidi, 70. iodi compositus, 82. plumbi subacetatis, 141. Litharge, 139. Lithia water, 150. Lithium, 149. bicarbonate, 150. bromide, 149. carbonate, 150. chloride, 149. Loadstone, 134. Loganiaceae, alkaloids of, 431. Lucifer disease, 106. Lugol's solution, 82. Lunar caustic, 165. Lutidines, 398. Lysidine, 299. Lysol, 347. Maclaurine, 360. Magma bismuthi, 143. Magnesia, 173. mixture, 109. Magnesite, 174. Magnesium, 173. carbonate, 174. chloride, 173. group, 172. 468 INDEX Magnesium, hydroxide, 173. organic compounds, 289. oxide, 173. phosphates, 174. pyrophosphate, 174. sulphate, 173. Magnetic oxide, 134. Malachite, 181. Malonyldimethylurea, 404. Malonylguanide, 405. Malonylurea, 404. group, 403. Malt, 214. Maltose, 244. Manganates, 132. Manganese, 131. oxides, 131. salts, 132. Manganite, 131. Mannitan. 225. Mannite, 225. Mannitol, 225. Mannose, 240. Marble, 170. Marsh gas, 203. Martius' yellow, 387. Mass, action, 51. Massicot, 130. Matter, 1. general properties of, 2. states of, 4. Meconine, 436. Meerschaum, 173. Megohm, 21. Melampyrite, 225. Melecitose, 245. Melitose, 245. Membranes, permeable, 9. semipermeable, 10. Menthan, 383. Menthol, 383. Mercaptals, 286. Mercaptans, 285. Mercaptides, 285. Mercurammonium chloride, 188. Mercurdiammonium chloride, 188. Mercuric chloride, 187. cyanide, 188. fulminate, 308. iodide, 188. nitrate, 189. oxide, 185. sulphate, 189. Mereurous chloride, 186. iodide, 188. nitrate, 189. nxiili'. 185. sulphate, 189. Mercury. I si. aimnonialrd. 188. chlorides. I s *''- formaniide, 312. fulminating, 308. Mercury, iodides, 188. nitrates, 189. oxides, 185. phenate, 346. sulphates, 189. Meroquinene, 431. Mesitylene, 342. glycerol, 352. Meso compounds, 202. Mcsnxalyhirea, 266, 405. Metachloral, 231. Meta compounds, 338, 339. Metudiazine, 309. Metadioxybenzene, 349. Metaldehyde, 230. Metallocyanidea, 309. Metalloids, 51. Metals, 51, 53. noble, 102. Metamerism, 194. Metathesis, 33. Methanal, 228. Methane, 203. series, 201. triphenyl, 389. Methemoglobin, 273. Methene chloride, 206. Methenyl, chloride, 206. iodide, 207. Method, see Test. Methol, 279. Methoxyben/aldehyde, 354. Methoxyparaoxybenzaldehyde, 354. Methyl, amine.' 295. acetanilide, 372. benzene, 342. bromide, 207. carbinol, 214. carbylamine, 306. chloride, 205. coniine, 422. cyanide, 306, 313. ethyl oxide, 267. glycocollj 323, 324. guanidine, 301. hydride, 203. hydroxide, 214. indoles, 415, 416. iodide, 207. isocyanide, 306. ieopropylcarbinol, 221. morphine, 434, 438. morphine methine, 438. oxalate, 387. oxide, 267. phenylhydrazine, 380. piperidine. 398. propylcarhinol. 221. pyridines, 398. quinine. 430. slryclmium iodide, 432. uraeils, 402. uramine, 301. INDEX 469 Methyl, xanthines, 410. Methylal, 233. Methylene, chloride, 206. Meunier's compounds, 291, 371. Mica, 173, 178, 180. Microhm, 21. Milliampere, 21. Mineral green, 183. Minderus, spirit of, 167. Minium, 139. Mitis green, 183. Mixture, 22. Mixtures, isomorphous, 23. of solids, 23. Mol, 29. Molasses, 242. Molecule, 24, 25. Molecular theory, 24. volume, 29. weight, 26. determination of, 195. Molybdenum, 128. Monacetin, 223, 280. Monads, 30, 31. Monamides, 310. primary, 311. secondary, 311. tertiary, 311. Monamines, 292. primary, 292. secondary, 294. tertiary, 295. Monobenzenic compounds, 341. paraquinones, 351. Monobromocamphor, 384. Monochlormethyl chloride, 206. Monoethylic sulphate, 277. Monoglycerides, 223, 280. Monoketones, 233, 354. Monomorphyl sulphate, 434. Mononitroparaffins, 292. Monophenyl sulphate, 366. Monosaccharides, 236. Monoses, 236. Monothioethylene glycol, 286. Monsel's salt, 136. Monurei'des, 316. Morphine, 434, 438. Morphium, 420. Morrhuine, 282. Mucilages, 246. Murexide, 404. Muscarin, 297. Must, 218. Mustard oils, 308, 333, 363. Myazine compounds, 400. Mydaleme, 300. Myrosin, 333, 361. Naphtha, 204. Naphthalene, 386. Naphthenes, 381. Naphthol yellow, 387. Naphthols, 386. substituted, 387. Naphthoquinones, 387. Narceine, 436, 438. Narcotine, 436, 438. Nascent state, 59. Negative plate, 19. pole, 19. Neon, 72. Neuridine, 300. Neurine, 297. Neutral reaction, 33. Nickel, 180. group, 180. sulphate, 180. Nicotine, 423. Niobium, 128. Niton, 72. Nitrates, 102. Nitre, 157. Nitrile bases, 292. Nitriles, 303, 305. acid, 305. of carbonic acids, 307. of thiocarbonic acids, 307. Nitrites, 101. Nitro, 292. acids, 321, 370. alcohols, 319. aldehydes, 319. anisols, 369. benzenes, 367. benzol, 367. cellulose, 247. cresols, 370. Nitrogen, 94. acids of, 100. amide, 293. amino, 293. azo, 293. bromide, 97. chloride, 97. diazo, 293. dioxide, 98. group, 93. halides, 97. hydrazo, 293. imide, 293. imino, 293. iodide, 97. monoxide, 97. nitrile, 293. oxides of, 97. pentoxide, 100. peroxide, 99. tetroxide, 99. trioxide, 99. Nitroglycerin, 280. Nitroketones, 319. Nitroparaffins, 292. Nitrophenetols, 369. Nitrophenols, 369. Nitrosonaphthols, 387. 470 INDEX Nitrosophenols, 370. Nitrosyl bichloride, 102. chloride, 102. Nitrotoluenes, 368. Nomenclature, 42. of alcohols, 211, 221. of alkaloids, 420. of amines, 293. of carbon compounds, 198. Non-metals, 52. Nonoses, 236. Nordhausen oil of vitriol, 93. Normal compounds, 202. conditions, 4. Nortropan, 424. Nuclein bases, 409. Nucleus, 200. benzene, 334. Obtained substances, 208. Occlusion, 58. Octoses, 236. Ohm, 21. Oil, bone, 397. cod-liver, 282. fusel, 220. mustard, 333. of bitter almonds, 353. of Dippel, 397. of vitriol, 90. sperm, 282. Oils, drying, 282. fixed, 282. greasy, 282. lubricating, 204. mustard, 308. neutral, 282. non-drying, 282. semi-drying, 282. Ol, 211. Olefiant gas, 327, 328. Olefine, 327. acetylene series, 201. series, 201, 327. terpenes, 382. Olefines, 201. Oleoresins, 385. Open chain compounds, 199, 201. Opium alkaloids, 434, 437. Optical activity, 238. isomeres, 239. Organic compounds, 191, 192. Organo-halide compounds, 289. Organo-magnesium compounds, 289. Organo-metallic compounds, 288. Orientation, 337. Orpiment, 114. Ortho acids, 108. compounds, 338, 339. diazine, 399. dioxybenzene, 349. quinones, 350. Osazones, 236, 249, 380. Ose, 236. Osmium, 128. Osmosis, 9. Osmotic equivalent, 9. Otoliths, 170. Oxalylurea, 395. Oxazine, 399. Oxethylamine, 319. Oxhydryl, 37. Oxidation, 60. Oxides, 61. basic, 61. indifferent, 61. neutral, 61. saline, 61. Oxime group, 301. Oxindole, 374, 417. Oxonium compounds, 289. Oxyacids, 36, 259. Oxyuldehydes, 228. Oxyamides, 322. Oxyamines, 296, 298, 319. Oxybenzaldehyde, 354. Oxycholine, 298. Oxycinchonine, 430. Oxycyanides, 228. Oxydimorphine, 434. Oxygen, 59. Oxygenium, 59, 60. Oxy hemoglobin, 273. Oxyhydrocymene, 383. Oxyindole, 416. Oxymorphine, 434. Oxynaphthalenes, 386. Oxyneurine, 298. Oxyphenylalanine, 374. Oxyphenylethylamine, 375. Oxypurines, 411. Oxysalts, 38. Ozocerite, 204. Ozone, 61. Ozonic ether, 70. Painter's colic, 141. Palladium, 147. Papaveraldine, 437. Papaverine, 436, 437. Para acetophenetidine, 373. Para compounds, 338, 339. coniine, 423. dioxybenzene, 349. Paraffin, 204. series, 201. Paraffins, 202. amido, 292. haloid derivatives of, 204. imido, 293. monohalogen, 205. nitro, 292. nitrogen derivatives of, 291. oxidation products of, 208. sulphur derivatives of, 285. Para formaldehyde, 228. INDEX 471 Paraldehyde, 230. Paramorphine, 436. Paramylum, 246. Para quinones, 351. triazine, 414. xan thine, 410. Parchment paper, 247. Paris green, 115, 183. yellow, 140. Pearl ash, 159, 160. Pentads, 30, 31. Pentamethylenediamine, 299. Pentene, 330. Pentites, 225. Pentoses, 236, 237. Pentosides, 361. Periodic law, 54, 55. Perissads, 30. Permanganates, 132. Petrolatum, 204. Petroleum, 204. ether, 204. Phenacetine, 373. Phenanthrene, 385. alkaloids, 422, 433. Phenates, 346. Phenetidines, 369, 373. Phenetol, 361. Phenol, 345. cymylic, 347. dyes, 350. esters, 347. methylisopropyl, 347, 348. phthalem, 350. sulphonates, 366. synthetic, 345. Phenols, 344, 386. benzylic, 347. cresylic, 347. dihydric, 348. dimethyl, 347. diphenyl, 389. ethyl, 347. monohydric, 344. substituted, 348. trihydric, 350. Phenones, 354. Phenyl, 343. acetamide, 372. alanine, 374. amines, 371, 373. benzenes, 388. carbylamine, 373. dimethylpyrazolon, 394. Phenylene, 343. diamines, 373, 380. Phenyl glucosides, 361. glycocoll, 375. guanidine, 375. hydrazine, 379, 380, 381. test, 249. hydrazones, 380. hydroxide, 345. Phenyl hydroxylamine, 370. isocyanide, 306. salicylate, 358. sulphide, 365. uracil, 402. urethanes, 314, 375. Phloretin, 364. Phloridzin, 364. Phloroglucin, 350, 364. Phlorose, 364. Phosgene, 271. Phosphates, 109. Phosphine, 106. Phosphines, 326. Phosphorus, 103. acids of, 107. halides, 107. organic compounds of, 326. oxides, 107. oxychloride, 107. pentachloride, 107. pentoxide, 107. trichloride, 107. trioxide, 107. Phthalamide, 373. Phthaleins, 350. Phthalimide, 373. Physical change, 1. Physostigmine, 441. Picolines, 398. Pilocarpene, 428. Pilocarpidine, 428. Pilocarpine, 428. Pinacone, 222. Piperazine, 400. Piperidei'nes, 398. Piperidine, 398, 423. alkaloids, 421, 422. Piperidines, 398. Piperine, 423. Plaster of Paris, 170. Platinic chloride, 148. Platinum, 147. black, 147. group, 147. spongy, 147. tetrachloride, 148. Plumbago, 125. Plumbates, 140. Plumbites, 139. Pceonin, 350. Poisons, 78, and see Toxicology. Poles, electric, 19. Polymerism, 194. Polymerization, 229. Polymethylenes, 335. Polysaccharides, 236, 245. Ponceau dyes, 387. Populin, 364. Porcelain, 218. Porter, 218. Positive plate, 19. pole, 19. 472 INDEX Postulate, see Law. Potash, 156, 157, 160. Potassa, 156. Potassium, 156. acetate, 159. alcoholate, 217. alum, 179. arsenite, 115. bromate, 157. bromide, 157. carbonates, 159. chlorate, 158. chloride, 157. cyanates, 307. cyanide, 162. dichromate, 159. ethylate, 217. ferricyanide, 163. ferrocyanide, 162. hypochlorite, 158. hydrate, 156. hydroxide, 156. iodide, 157. myronate, 333. nitrate, 157. oxalates, 160. oxides, 156. permanganate, 159. phenate, 346. pyrosulphate, 159. sulphates, 158. sulphites, 159. tartrates, 160. Powder of Algaroth, 121. putty, 146. smokeless, 247. Precipitation, 67. Pressure, 4. critical, 15, 16. Preston salts, 167. Process (see also Reaction, Reagent, Test). ammonia, 155. Leblanc's 155. Solvay, 155. Proline, 393. Propanon, 234. Propantriol, 223. Propine, 330. Propyl carbinol, 220. hydroxide, 219. piperidine, 398, 422. Propylene, 330. Proteinochrome, 416. Proteinochromogen, 416. Prussian blue, 136, 163. Pseudo aconitine, 440. conhydrine, 422. morphine, 434. Ptomaines, 442. Purine, 406. bases, 409. compounds, 400. Purine group, 400, 405. Purpurin, 388. Putrefaction, 443. Putrescin, 299. Putty powder, 146. Pyrazine, 399. Pyrazolons, 394, 395. Pyridiazine, 399. Pyridine, 397. alkaloids, 421. bases, 397. homologues, 398. methylpyrrole, 424. Pyrimidine, 399. derivatives, 400. Pyrites, 84, 110, 132, 134. copper, 181. Pyrocatechin, 349. Pyrocatechol, 349. Pyrocomane, 398. Pyrodine, 381. Pyrogallol, 350. Pyrolusite, 131. Pyrone, 397. Pyroxam, 245. Pyroxylic spirit, 252. Pyroxylin, 247. soluble, 247. Pyrrazoles, 393. Pyrrole, 392, 424. Pyrrolidine, 393. alkaloids, 421. piperidine alkaloids, 421, 424. pyridine alkaloids, 421, 423. Pyrroline, 393. Pyrromonazoles, 393. Quaternary ammonium compounds, 295, 296, 297, 298. hydroxides, 293. Quercite, 382. Quicklime, 168. Quicksilver, 185. Quina red, 360. Quinicino, 430. Quinidine, 430. Quinine, 429. hydrosulphate, 429. sulphate, 429. Quinol, 349. Quinoline, 419. alkaloids, 421, 428, 429. compounds, 418. Quinone, 351. Quinones, 350, 386, 387. Quinoxime, 370. Radicals, 45, 192. of acids, 46. Raffinose, 245. Reaction, 32 (see Process, Reagent, Test). Reactions, 33. INDEX 473 Reagent, Frohde's, 435. Marquis', 436. Nessler's, 96. Schiff's, 315. Realgar, 114. Reaumur's scale, 12. Rectified spirit, 217. Reduction, 58. Refractory substances, 13. Residues, 46. Resins, 384. Resistance, 20. Resorcin, 349. Resorcinol, 349. phthalei'n, 350. Reversible reactions, 50. Rhamnose, 237. Rhigolene, 204. Rhodium, 147. Ribose, 237. Rings, 200. Roburite, 368. Rochelle salt, 162. Rock crystal, 127. Rosin, 382. Rubidium, 163. Ruby, 178, 181. Ruthenium, 147. Sabadilline, 441. Saccharates, 238, 241, 243. Saccharin, 366. Saccharobioses, 236, 241. Saccharose, 242. Saccharotrioses, 236. Saccharum lactis, 244. Sal ammoniac, 166. Salacetol, 358. Salseratus, 160. Salicin, 364. Salicyl hydride, 354. Salicylal, 354. Salicylide, 364. Saligenin, 352. Salipyrine, 394. Salol, 358. Sal soda 155. Salt, 152. of lemon, 160. of Saturn, 140. of sorrel, 160. of tartar, 159, 160. rock, 152. sea, 152. soda, 155. table, 152. Saltpeter, 157. Chile, 152. cubic, 152. Salts, 36, 38, 39. acid, 38, 45. basic, 38, 45. double, 45. Salts, haloid, 38. modified, 397. neutral, 45. normal, 45. Sal volatile, 167. Sanguinarine, 397. Santonin, 364. Saponification, 276. Sapphire, 178. Saprine, 300. Sarcosine, 324. Sarkine, 411. Saturated compounds, 196, 201. Scandium, 177. Scheele's green, 115, 183. Schweinfurth green, 115, 183. Scopolamine, 427. Scopoline, 427. Seidlitz salt, 173. Selenite, 169. Selenium, 93. Selenmonazole, 393. Series, electrochemical, 34. Silex, 127. Silica, 127. Silicates, 127. Silicium, 127. Silicon, 127. carbide, 127. chloride, 127. dioxide, 127. Silver, 164. acetylide, 329. bromide, 165. chloride, 165. fulminate, 308. german, 180. iodide, 165. monoxide, 164. nitrate, 165. oxides, 164. Skatole, 416. Smokeless powder, 247, 280, Soaps, 282. Soapstone, 173. Soda, 155. baking, 156, 161. blackball, 155. caustic, 155. crystals, 155. lye, 152. salt, 155. washing, 155. water, 272. Sodium, 151. acetate, 155. acetylide, 329. alcoholate, 217. arsenates, 154. arsenites, 115, 154. bicarbonate, 156. borate, 154. bromide, 152. 474 INDEX Sodium carbonates, 155. chlorate, 154. chloride, 152. dioxide, 151. ethylate, 217. group, 149. hydroxide, 151. hypochlorite, 154. hyposulphite, 153. iodide, 152. metaphosphate, 154. monoxide, 151. nitrate, 152. nitroprusside, 310. oxides, 151. permanganate, 155. phosphates, 153. pyroborate, 154. pyrophosphate, 154. sesquicarbonate, 156. silicates, 153. sulphates, 152. sulphite, 153. sulphovinate, 277. thiosulphate, 153. tungstate, 128. Solanidin, 364. Solanin, 364. Solids, 4. Solute, 14. Solution Solutions, 14. chemical, 14. concentration of, 37. decinormal, 38. dilute 14, 15. equivalent normal, 38. molecular normal, 37. normal, 37. percentage, 37. physical, 14. physiological salt, 152. salt, 152. saturated, 15. simple, 14. solid, 23. standard, 38. strength of, 37. supersaturated, 15. unsaturated, 15. Solubilities, table of, 446, 447. Solubility, 14. Solvay process, 155. Solvent, 14. Somnal, 314. Rorbinose, 241. Sorbite, 225. Sorbitol, 225. Space isomerism, 238. Spasmotoxine, 443. Specific heat, 17. volume, 4. weight, 3. Spermaceti, 279. Spirit, methylated, 214. neutral, 219. potato, 220. proof, 218. pyroxylic, 214, 252. wood, 214. Spirits, 216, 219. of Minderus, 167. of wine, 214. Spiritus rectificatus, 217. Stability, 48. Stable substances, 49. Stannates, 146. Stannic chloride, 146. oxide, 146. Stannous chloride, 146. hydroxide, 146. oxide, 146. Starch, 245. animal, 245. cellulose, 245. hydrated, 245. paste, 245. soluble, 245. States of matter, 4. Steel, 133. Stereochemistry, 238. Stereoisomerism, 238. Stethol, 279. Stibine, 121. Stibines, 326. Stilbene, 389. Stoichiometry, 41. Storax, 352. Strontianite, 171. Strontium, 171. Strychnidene, 432. Strychnine, 431. Strychnos alkaloids, 431. Styracol, 349. Sublimate, corrosive, 187. Sublimation, 17. Subsidence, 68. Substance, 1. Substitution, 196. Succinyl morphine, 434. Sucrates, 243. Sugar, beet, 243. barley, 243. burnt, 243. candy, 243. cane, 242. diabetic, 240. fruit, 241. gelatin, 323. grape, 240. invert, 241, 243. liver, 240. maple, 243. milk, 244. muscovado, 242. of lead, 140. raw, 242. INDEX 475 Sulphates, 92. Sulphethylates, 277. Sulphides, 87, 284. Sulphites, 89. Sulpho, 85. Sulphocarbolates, 366. Sulphonal, 287. Sulphonation, 365. Sulphones, 284, 286, 366. of thioaldehydes, 286. Sulphosion, 89. Sulphurylchloride, 88. Sulphovinates, 277. Sulphoxides, 284, 286. Sulphur, 84. aromatic derivatives of, 365. dioxide, 87. flowers of, 84. group, 83. milk of, 84. oxides, 87. oxyacids of, 89. plastic, 84. precipitated, 84. roll, 84. sublimed, 84. trioxide, 88. Sultones, 387. Symbols, 31. Symmetrical positions, 338. Synthesis, 33, 63. Talc, 173. Tannins, 360. Tantalum, 128. Tartar, cream of, 161. crude, 161. emetic, 162. salt of, 159, 160. soluble, 160. Tartrates, 160. Tartronylurea, 404. Tellurium, 93. Temperature, 11. absolute, 13. critical, 15. Terpenes, 382. Terpin hydrate, 383. Terpins, 383. Terra alba, 170. Test (Process, Reaction). Almen, 249. Anderson, 397. bismuth reduction, 249. biuret, 315, 318. Boettger, 249. copper reduction, 248. Fehling, 248. fermentation, 249. Fischer, 249. furfurole, 247. Gallois, 383. Hoffman, 295, 375. Test, Hofmeister, 326. Husemann, 436. indophenol, 372. Kjeldahl, 195. Kossel, 411. Marsh, 118. Mulder-Neubauer, 418. murexide, 408. Nessler, 96. Nylander, 249. osazone, 249. Pavy, 248. Pellagri, 435. phenylhydrazine, 249. pine-shaving, 346, 392, 393, 416. Piria, 375. pyrrole, 416. Eeinsch, 117. Riegler, 249. Scherer, 326, 375, 383. Tollens, 247. Trommer, 248. Wiedel, 402. Tetanine, 443. Tetanotoxine, 443. Tetrads, 30, 31. Tetra hydrobenzenes, 335. hydrodiphenyl, 388, hydronaphthols, 387. hydropyridine alkaloids, 421. hydropyridines, 398. hydropyrrole, 393. hydrostrychnine, 432. ketohexahydropyrimidine, 405. ketones, 235. methylammonium hydroxide, 295. methylenediamine, 299. methylethylene glycol, 222. methyleneimine, 393. Tetronal, 287. Tetroses, 236, 237. Thallium, 168. Thebaine, 436, 439. Thebaol, 439. Theine, 411. Theobromine, 410. Theophylline, 410. Theory, atomic, 24. molecular, 24. Therm, 12. Thermal capacity, 17. unit, 12. Thermometers, 11. Thiazine, 399. Thio, 85. acetals, 286. acids, 284, 287. alcohols, 284, 285. aldehydes, 284, 286. anhydrides, 87, 287. antimonates, 122. antimonites, 122. aromatic compounds, 365. 476 INDEX Thio azoles, 393. bases, 37. Thiocol, 349. Thio ethers, 284, 285. ethylates, 285. glycols, 285. ketones, 284. Thiophene, 392. Thiophenol, 365. Thiourea, 316. Thymine, 402. Thymol, 347. Tin, 145, chlorides, 146. crystals, 146. foil, 146. group, 144. hydrates, 146. oxides, 146. plates, 146. Tinstone, 146. Tinctures, 216. Titanium, 144. Toluene, 342. sulphamide, 366. sulphonic chlorides, 366. Toluidines, 372. Toluol, 342. Toluyl benzene, 388. Toluylene, 389. Tolypyrine, 395. Topaz, 178. Toxalbumins, 443. Toxicology, 78, 116, and see Poisons, Corrosives. aconite, 440. aldehyde, 230. ammonia, 167. aniline, 371. antimony, 123. arsenic, 115. atropine, 426. barium, 172. bismuth, 144. carbolic acid, 346. carbon dioxide, 274. carbon disulphide, 288. carbon monoxide, 271. chloral hydrate, 232. chloroform, 207. copper, 184. cyanides, 304. digitalis, 363. hydrogen sulphide, 86. illuminating gas, 271. iodine, 82. lead, 141. mercury, 189. mineral acids, 78. nicotine, 424. nitric acid, 103. nitrobenzene, 368. nitrogen Ictroxide, 100. opium, 439. Toxicology, oxalic acid, 258. phenol, 346. phosphorous, 105. potassium, 163. silver, 165. sodium, 163. strychnine, 433. sulphuric acid, 92. zinc, 177. Toxines, 443. Transposition, 33. Transterpene, 383. Triacetin, 223, 280. Triacetonamine, 319. Triads, 30, 31. Triamides, 310. Triamines, 292. Triazines, 413. Tribrommethane, 207. Tributyrin, 281. Tricaprin, 281. Tricaproin, 281. Tricaprylin, 281. Trichlor aldehyde, 230. methane, 206. Tricyanogen chloride, 304. Tryglycerides, 223, 280. Triiodomethane, 207. Triketones, 235, 354. Triketohexahydropyrimidine, 404. Triketopurine, 406. Triketotetrahydroglyoxaline, 395. Trimargarin, 281. Trimethylamine, 295. Trimethylcarbinol, 220. Trimethylethylene, 330. Trimethylene diamine, 299. Trimethyloxethylammonium hydroxide, 296. Trimethyloxethylideneammonium hy- droxide, 296. Trimethylvinylammonium hydroxide, 297. Trimorphism, 8. Trinitroglycerol, 280. Trinitrophenols, 369. Triolein, 281. Triols, 223. Trional, 287. Trioses, 236, 237. Trioxyanthraquinone, 388. Trioxycyanidine, 307. Trioxymethylene, 228. Tripalmitin, 281. Triphenylbenzene, 388. Triphenylmethane, 389. Triple phosphate, 174. Trisaccharides, 236, 245. Tristearin, 281. Tropan alcohol, 425. alkaloids, 421, 424. Tropeines, 427. Troprolins, 387. Tropidine, 425. INDEX 477 Tropine, 398, 425. atropate, 427. tropate, 425. Tryptophane, 416. Tungsten, 128. TurnbulPs blue, 137, 163. Turner's yellow, 140. Turpentine, 382. Turpeth mineral, 189. Tutty, 176. Tyrosine, 374. Unsaturatod compounds, 197. Unsymmetrical positions, 338. Uracil, 401. group, 400, 401. Uralium, 314. Uranium, 137. Uranyl, 138. Urates, 408. nitrate, 138. Urea, 314. nitrate, 315. oxalate, 315. Ureas, compound, 316. Ureides, 316. diacidyl, 317. mixed, 317. monacidyl, 317. Urethanes, 313. Urotropin, 319. Uroxanthine, 417. Valence, 30. Valerene, 330. Vanadium, 128. Vanillin, 354. Vapor, 15, 16. latent heat of, 16. Vaporization, 15. Varech, 81. Vaseline, 204. Veratrine, 441. Veratrol, 349. Verdigris, 183. Veronal, 404. Verona yellow, 140. Vichy salt, 156. Vicinal positions, 338. Vinegar, 252. wood, 252. Vitriol, blue, 183. green, 135. oil of, 90. white, 176. Volt, 21. Volume, specific, 4. Water, 62. baryta, 172. chlorine, 75. in the body, 69. lime, 169. lithia, 150. Water, maximum density of, 13. of constitution, 64. of crystallization, 8, 63, 64. oxygenated, 69. soda, 272. Waters, bitter, 174. chlorides in, 65. hardness of, 66. impurities in, 65. lead in, 67. mineral, 68. natural, 64. nitrogen in, 66, 67. organic matters in, 66. poisonous metals in, 67. potable, 64, 65. purification of, 67, 68. solids in, 65. Watt, 21. Wax, 204. Weight, 2. absolute, 3. apparent, 3. atomic, 26. equivalent, 31. molecular, 26, 195. relative, 3. specific, 3. White lead, 138, 141. precipitate, 188. Wines, 218. Witherite, 172. Wort, 215. Xanthine, 410. bases, 409. Xanthone, 358. Xenols, 347. Xenon, 72. Xylenes, 342. Xylenols, 347. Xylidines, 372. Xylodin, 245. Xylols, 342. Xylose, 237. Xylyleneglycols, 352. Yeast, 215. Yellow wash, 186. Zero, absolute, 13. Zinc, 175. alkyls, 288. butter of, 176. carbonate, 176. chloride, 176. ethide, 288. ethyl, 288. hydroxide, 176. methide, 288. methyl, 288. oxide, 176. sulphate, 176. Zirconia, 145. Zirconium, 145. ELEMENTS "o Atomi c Weight "o Atomi c Weight NAME I >, C/) Approx- itnate Interna- tional (1918) O=i6 NAME a h in Approx- imate Interna- tional (19.8) O = i6 Aluminium Antimony Al 27 27.1 Molybdenum Neodymium Me Nd 96 144 96.0 144.3 (Stibium) Sb 120 120.2 Neon NP 20 202 Argon A 40 39.88 Nickel Ni 58 58 68 Arsenic As 75 74.96 Niton (Radium Barium . . Ba 137 137.37 Emanation ) Nt, 222 222.4 Bismuth Bi 208 208.00 Nitrogen . N 14 14.01 Boron B 11 11.0 Osmium . . OR 191 190.9 Bromine Br 80 79.92 Oxygen .... O 16 16.00 Cadmium Cd 112 112.40 Palladium Pd 107 106.7 Caesium Cs 133 132.81 Phosphorus P 31 31.04 Calcium Ca 40 40.07 Platinum . Pt 195 195.2 Carbon C 12 12.005 Potassium Cerium Ce 140 140.25 ( Kalium ) K 39 39.10 Chlorine Cl 35.5 35.46 Praseodymium ( c ) Pr 141 140.9 Chromium Cr 52 52.0 Radium . . . Ra 226 226.0 Cobalt On 59 58.97 Rhodium Rh 103 102.9 Columbium (a) . . Cb 93 93.1 Rubidium Rb 85 85.45 Copper ( Cuprum ) Cu 63 63.57 Ruthenium Ru 102 101.7 Dysprosium .... Dy 162 162.5 Samarium Sa 150 150.4 Erbium Er 168 167.7 Scandium 8c 44 44.1 Europium Eu 152 1520 Selenium Se 79 79.2 Fluorine F 19 19 Silicon . Si 28 28.3 Gadolinium Gd 157 157.3 Silver (Argentum) Ap 108 107.88 Gallium Ga 70 69.9 Sodium (Natrium) Na 23 23.00 Germanium Ge 72 725 Strontium Sr 87.5 87.63 Glucinum (6) Gl 9 9 1 Sulphur s 32 32.06 Gold (Aurum) . . Helium Au He 197 4 197.2 4 00 Tantalum Tellurium . . . Ta Te 181 127 181.5 127.5 Holmium Ho 163 163 5 Terbium Tb 159 159.2 Hydrogen H 1 1 008 Thallium T1 204 204.0 Indium In 115 114 8 Thorium Tli 232 232.4 Iodine . . I 127 12692 Thulium Tm 168 168.5 Iridium Ir 193 193 1 Tin (Stannum) . . Sn 118.5 118.7 Iron ( Ferrum ) Fe 50 55 84' Titanium Ti 48 48.1 Krypton Kr 83 8292 Tungsten Lanthanum La 130 139 ( \Volframium ) W 184 184.0 Lead (Plumbum) PI) 207 207 20 Uranium TT 238 238.2 Lithium Li 7 694 Vanadium V 51 51.0 Lutecium Lu 17 r > 175 Xenon Xe 130 130.2 Magnesium Mg 24 24.32 Ytterbium (d) .. Yh 173 173.5 Manganese Mn 55 5493 Yttrium Yt 89 88.7 Mercury Zinc Zn 65 65.37 ( Ui/drctrourum } HP 200 2006 Zirconium Zr 90 90.6 **c (a) Also formerly known as Niobium, Nb. (6) Also formerly known as Beryllium, Be. (c) Also formerly known as Didymium, Di. (d) Also known as Neoytterbium. Ci o Ci 1 rH 1 o 1 1 s s I-H rH CO 1 co r* 1 " A, | H ^n 1 Ti 1 f3 Cd o s PH u M s II Ti 1 Oi 1 0) 0> CM O M I i" i (M 1 i CL W C* !i 10 (H Tj I s p Ci l-H 5 1j PQ o II 1 1 1 1 i j I l-H CO Ti CM JJ H o ii PQ S d I | Tf o CM juj 1 (M CO ' fc 1 ' O Tl O II bo a s ii d N 1 m Is II & i H s OJ HH fl CO CO co i r~. Ci B ,q w * II ^ 1) M Ti ' . ^ Ci CO ->-> ca fl c - UNIVERSITY OF CALIFORNIA Medical Center Library THIS BOOK IS DUE ON THE LAST DATE STAMPED BELOW Books not returned on time are subject to a fine of soc per volume after the third day overdue, increasing to $1.00 per volume after the sixth day. Books not in demand may be renewed if application is made before ex- piration of loan period. AI Ai Ai Ai Bi B( Bi Ca Ca Ca Cs C Cl Cl Cc Cc Cc Ei Ei Fl Gi GJ Gc Gl G< Hi H. H In 57n-7,'52(A2508s2)4128 Iridium Ir 193 193.1 Tin (Stannum) . ' Sn 118.5 118.7 Iron (Ferrum) . Fe 50 55.84 ' Titanium Ti 48 48.1 Krypton Kr 83 82.92 Tungsten Lanthanum Lead (Plumbum) La Pb 139 207 139.0 207.20 ( \Volframium) . Uranium W TT 184 238 184.0 238.2 Lithium Li 7 6.94 Vanadium V 51 51.0 Lutecium Lu 175 175.0 Xenon Xe 130 130.2 Magnesium Manganese Mg Mn 24 55 24.32 54 93 Ytterbium (d) .. Yttrium Yb Yt 173 89 173.5 88.7 Mercury Zinc 65 65.37 ( Hydrargyrum ) Hff 200 2006 Zirconium Zr 90 90.6 (a) Also formerly known as Niobium, Nb. (6) Also formerly known as Beryllium, Be. (c) Also formerly known as Didymium, Di. (d) Also known as Neoytterbium. OS 2 1 II II d j| OH i rH co co _> B-. rH cs PM | II II 1 Tj 1 P PH z r i i O co l-H OS >o II fj 1 1 II 1 0) pj CO Pi C M | 1C ^ | 1 J^ 1 16 00 c^ 1 1 ^ _ co II II PL, W O II 10 II g P^ pq OS 5 "fi PQ M O IT 5 1 1 1 i i I CO 5 | 1 C SYSTEM. > O CO rH II O II OQ (M Ii fc Jj OQ co o II 1 II n g oo 1 CO i II t-I 01 1 P4 o5 to -M cy , 1 M te> 1 co o I itf< p!] *n < co 3 2 n s 1 1 | S PH PH rH cs CO || || fri ^ H O II II ,2 1 1 1 -5 PH ^ L> H 1 S -^ W > 1 GO oa II (N cs 1 s 5 f H W (M II 00 o os is J! s .SJ fe 3 H 3 1 I II n II ILLUSTRA o II II H N j as atomic national At( M M Cd 1 O 1 * 1 II o rt< h 1 CO i i s II H g rH II CO K II 11 T3 cy O -M ;T ^H rH ^3 PH 3 W HH- i i 04 CO r-1 1 ^ 00 *Q PQ *" H . || II i i cN 2 <5 II II CO 3 ,2 H O 3 o n CJ CO II OQ s S n PQ OS K cq c3 ,_i CO CO GO i f ^ II 1 1 d CO O i OS W II II i rH II ^ J & OS 5 ^ 2 5 o J n 1 u 1 PH P 1 o (M 1 1 1 II O o OJ 1 1 1 . 1 a OO CS = 2 Q