rSSflri Sfc& /ittS" 'VAv *.;-i?v. 3#&; VrrV ;?'t-.^ ';*?. $^&F#&h :.% t/*-v; f>-. ►v; *"'.-, •A V-' !& A New Series of Manuals. FOR MEDICAL STUDENTS. UNIFORM IN SIZE, PRICE AND BINDING. Price of Each Book, Cloth, $3.00; Leather, $3-5°- J2&. —PRESENTED TO— Physician to, and Lecturer on Midwifery and the Diseases of Women at, Guy's Hospital, London, etc. 227 fine Engravings. " The illustrations are mostly new and well executed, and we heartily commend this book as far superior to any manual upon this subject."—Archives ofGynaecology, New York. " Sensible, practical and complete."—Medical Brief. " I have carefully read it over, and, as a teacher of midwifery, I consider the book ought to become one of the recognized text-books; the treatment and pathology of the various subjects treated are clear and concise."—-J. Algernon Temple, MD., Prof'. of Midwifery, and Gynecology, Trinity Medical School, Toronto. No. 4. PHYSIOLOGY. Fourth Edition. By Gerald F. 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With Illustrations, 50 Formulae, and Directions for preparing Artificial Human Milk, for the Artificial Digestion of Milk, etc. " Nothing that concerns disease as found in childhood seems to have escaped the author's attention. From introduction to the end it is replete with valuable information, and one reads it with the feeling that Dr. Goodhart is writing of what he has seen at the bedside. It need scarcely be added that the revisions and additions by the American editor are of much value, neither too full nor too spare, and very judicious."—Journal of the American Medical Association. No. 7. PRACTICAL THERAPEUTICS. Fourth Edition. With an Index of Diseases. By Ed. John Waring, m.d., f.r.c.p. Rewritten and Revised. Edited by Dudley W. Buxton, Assistant to the Professor of Medicine, University College Hospital, London. 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Among others it contains Tables of the Arteries, of the Bacilli, giving the Name, Habitat, etc.; of Ganglia, Leucomaines, Micrococci, Muscles, Nerves, Plexuses, Ptomaines, with the Name, Formula, Physiological Action, etc.; Comparison of Thermometers; Weights and Measures, of Vital Statistics, etc. OPINIONS OF PROMINENT MEDICAL TEACHERS. " The compact size of this dictionary, its clear type, and its accuracy are unfailing pointers to its coming popularity."—John B. Hamilton, Supervising Surgeon-General U. S. Marine Hospital Service, Washington. " It is certainly as convenient and as useful a volume as can be found, regarding contents as well as arrangement."—Julius Pohlman, Prof, of Physiology, University of Buffalo. " I have examined it with considerable care, and am very much pleased with it. It is a handy book for reference, and so far as I have examined it, it is accurate in every particular." —E. H. Bartley, Prof, of Chemistry, Long Island College Hospital, Brooklyn. 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Holland, M.D., Dean Jefferson Medical College, Philadelphia. 4®* Students will find this an extremely useful book of reference. The ana- tomical tables will be of great use in memorizing the arteries, muscles, etc. Small, Square 8vo, Half Morocco, as above, with Thumb Index, . . . $4.25 Plain Dark Leather, without Thumb Index, 3.23 A COMPEND OF CHEMISTRY, INORGANIC AND ORGANIC. LEFFMANN. NEW EDITIONS. Blakistows PQuiz-Compends? A New Series of Manuals for the Use of Students and Physicians. Price of each, Cloth, $1.00. Interleaved, for taking Notes, $1.25. From The Southern Clinic. " We know of no series of books issued by any house that so fully meets our approval as these ?Quiz-Compends?. They are well arranged, full and concise, and are really the best line of text-books that could be found for either student or practitioner." J8SF" These Compends are based on the most popular text-books, and the lectures of prominent professors, and are kept constantly revised, so that they may thoroughly repre- sent the present state of the subjects upon which they treat. <93r" The authors have had large experience as Quiz-Masters and attaches of colleges, and are well acquainted with the wants of students. 4SS"- They are arranged in the most approved form, thorough and concise, containing many illustrations, inserted wherever they could be used to advantage. 4®" Can be used by students of any college. *S~ They contain information nowhere else collected in such a condensed, practical shape. SPECIAL NOTICE. These Compends may be obtained through any Bookseller, Wholesale Druggist or Dental Depot, or upon receipt of the price, will be sent, postpaid, by the publishers. In ordering, always specify " Blakiston's ?Quiz-Compends? ". No. 1. HUMAN ANATOMY. Based on "Gray." Fourth Revised and Enlarged Edition. Including Visceral Anatomy, formerly published separately. 117 Illustrations. By Samuel O. L. Potter, m.d., Professor of the Practice of Medicine, Cooper Medical College, San Francisco ; late A. A. Surgeon, U. S. Army. No. 2. PRACTICE OF MEDICINE. Part I. Fourth Edition. Revised, Enlarged and Improved. By Dan'l E. Hughes, m.d., late Demonstrator of Clinical Medicine, Jefferson College, Philadelphia. No. 3. PRACTICE OF MEDICINE. Part II. Fourth Edition. Revised, Enlarged and Improved. Same author as No. 2. No. 4. PHYSIOLOGY. Fifth Edition, with new Illustrations and a table of Physiological Constants. Enlarged and Revised. By A. P. Brubaker, m.d., Professor of Physi- ology and General Pathology in the Pennsylvania College of Dental Surgery ; Demon- strator of Physiology, Jefferson Medical College, Philadelphia. No. 5. OBSTETRICS. Fourth Edition. Enlarged. By Henry G. Landis, m.d., Professor of Obstetrics and Diseases of Women and Children, Starling Medical College, Columbus, Ohio. 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COMPEND OF CHEMISTRY, INORGANIC AND ORGANIC; INCLUDING URINARY ANALYSIS. HENRY LEFFMANN, M.D., D.D.S., Professor of Chemistry in the Woman's Medical College of Pennsylvania, in the Pennsylvania College of* Dental Surgery, and in the Wagner Free Institute of Science; Food Inspector for the Pennsylvania State Board of Agriculture. THIRD EDITION, REVISED. PHILADELPHIA : P. BLAKISTON, SON & CO., 1012 Walnut Street. 1891. NLV'-VOHk .n'oAULMY OF MEDICINE NOV 221929 • /6 2.T //• Copyright, 1890. By P. BLAKISTON, SON & CO. Press of Wm. F. Fell & Co., \J 1220-24 SANSON! ST., PHILADELPHIA. PREFACE TO THIRD EDITION. In preparing a third edition of the Compend of Chemistry, I have endeavored simply to bring the book up to date, as far as concerns the gen- eral applications of Chemistry to Medicine and Dentistry. More space has been given to explanations of the nature and functions of acids and radicles, and the organic substitution compounds have been treated more at length. The general arrangement and classification agree essentially with that of the former edition. Books of this class do not always meet with favor at the hands of reviewers; but any one who has had experience in teaching at American Medical Colleges knows that as long as the present methods continue some such assistance is absolutely essential. It affords to the student an opportunity to keep up with the lectures, and obviates the necessity of taking voluminous notes, in which serious errors are liable to occur. Such books, of course, cannot claim any originality; their merit lies in their accuracy, perspicuity and judicious selection of facts. I am indebted to Mr. William Beam, for aid in the preparation of the work. H. L. 715 Walnut St., Phila. May, 1890. CONTENTS. PAGE General Principles. Elements—Notation—Nomenclature—Laws of Combination —Valency—Electrical Relations —Reactions —Radicles — Acids, Bases and Salts—Volume Combination — Classifi- cation, ...................... 9~37 Descriptive Chemistry. Hydrogen—Potassium — Sodium—Lithium—Caesium—Rubi- dium—Silver,................... 38-43 Chlorine—Bromine—Iodine—Fluorine,......... 44-48 Oxygen—Sulphur—Selenium—Tellurium......... 49~55 Calcium—Barium—Strontium—Lead,.......... 56-59 Copper—Mercury—Zinc—Magnesium—Cadmium,..... 59_62 Aluminum—Iron—Manganese—Chromium—Nickel—Cobalt, 63-69 Boron — Nitrogen—Phosphorus — Arsenic —Antimony—Bis- muth—Gold—Vanadium,.............. 70-85 Carbon—Silicon—Tin—Platinum—Rarer Elements, .... 86-94 Organic Chemistry. Nature of Organic Bodies—Transformations and Decompo- sitions—Isomerism and Other Relations—Classification, . . 95-107 Methanes — Alcohols—Aldehydes—Fat-Acids—M ethenes— Methenyl Series—Fats, Fixed Oils and Soaps—Turpenes— Benzenes—Camphors and Resins,...........108-138 Sugars and Starches—Glucosides—Tannins,.......139-144 Cyanogen and Derivatives—Substitution Ammoniums—Alka- loids—Azo-Compounds—Ptomaines and Leucomaines, . . 145-157 vii viii CONTENTS. Biological Chemistry. pagk Plant Chemistry—Animal Tissues and Secretions,.....i57-*72 Urinary Analysis,...................i73_I83 Antidotes,...................... *84 Table of Elements,.................. J 85 COMPEND OF CHEMISTRY. ELEMENTS. Chemistry is the science that investigates the composition of matter and the changes that take place in it. Matter is anything that occupies space and has weight. Changes may be physical or chemical. Physical change is in general that which occurs without change of composition. The most frequent instances of true physical change are those known as change of state. Matter exists in at least three states—the solid, liquid and gaseous. The conversion of a body from one of these conditions to the other takes place under the influence of change of temperature, and is not necessarily attended by any alteration of composition. Such is the case in the conversion of ice into water, or water into steam, or the reverse. The development of magnetic properties in iron is another example of a true physical change. In many cases the conversion of a solid into a liquid, or of a liquid into a gas, is attended by change of composition, and, therefore, is not merely a physical change. Chemical change is that attended by alteration of composition. The rusting of iron, burning of coal, rotting of animal and vegetable matter, are familiar instances of chemical change. Forms of Chemical Change.—These are combination, decomposition and re-arrangement. Combination is the association of bodies to form a new substance. Decomposition is the separation of a body into new sub- stances. Re-arrangement refers to cases in which new bodies are formed without combination or decomposition. Decomposition cannot be carried on indefinitely. No matter what substance is taken for experiment, there will ultimately be reached bodies which are incapable of further decompo- sition by any method known to us. For example, chalk may by heat be decomposed into two substances, one a colorless gas, called carbon dioxide; the other a white powder, called calcium oxide, or, more commonly, lime. These products are different from the chalk and from each other, but they 2 9 10 inorganic chemistry. do not represent the limit of decomposition, for by special methods each can be made to yield two substances. The lime yields a solid (called calcium) and a gas called oxygen; the carbon dioxide yields a solid (called carbon) and a gas which is the same as that from the lime, namely, oxygen. The substances obtained in this second step are incapable of further decomposi- tion by any known process. By proceeding in this way with all known substances chemists have determined the limits of decomposition, and have established that all material objects may be regarded as formed from a limited number of undecomposable substances. These are called elements. So far as at present known these elements are entirely independent forms, and are incapable of conversion into one another. About seventy-five elements are now known, and the number is from time to time increased by the discovery of new ones. Every substance must be either one of these elements or the result of a combination of two or more of them. Consequently all bodies are divided into two classes, elementary and compound. The main object of chemistry is to discover what elements are present in any body and what are the laws governing the action of the elements upon one another. Analysis and Synthesis.—When the composition of a body is deter- mined by separating the elements contained in it, the process is called analysis; when bodies are produced by combining elements the process is called synthesis. Nature of the Elements.—A table of all the elements at present defi- nitely known will be found at the end of the book. For the purpose of preliminary study it will be necessary to enumerate only a few, as many of the elements occur only in rare substances. For scientific purposes they are usually arranged in groups in which those bearing the closest resemblance are brought together. The following gives some of the more important groups, and the student will find it advantageous to commit these to memory, as the arrangement will aid in the study of compounds :— Oxygen Group. Oxygen, Chlorine Group. Chlorine, Nitrogen Group. Boron, Carbon Group. Carbon, Sulphur, Selenium, Tellurium. Bromine, Iodine, Fluorine. Nitrogen, Phosphorus, Arsenic, Silicon, Tin, Platinum. • Antimony, Bismuth, Gold. elements. 11 Potassium Group. Potassium, Sodium, Lithium, Hydrogen, Silver. Calcium Group. Calcium, Barium, Strontium, Lead. Zinc Group. Zinc, Magnesium, Cadmium. Copper Group. Copper, Mercury. Iron Group. Iron, Manganese, Aluminum, Chromium, Nickel, Cobalt. Recent observations on certain rare elements have indicated the possi- bility of breaking them into simpler forms, and it appears probable that in a few years our views as to the nature of the elements will undergo much change. Atomic Theory.—We may reduce any solid, a piece of sulphur, for in- stance, to powder, and it would seem as if no limit existed to such division. Chemists, however, are now generally of the opinion that a limit does exist, and that every substance is made up of particles of definite size and inca- pable of further division. Such particles are very small, and equally hard, no matter what the nature of the mass which they constitute. They are called atoms (a word signifying indivisible); any mass of elementary matter consists of a collection of a greater or less number of these atoms. It is believed that the atoms are rarely, if ever, perfectly free, but asso- ciated in groups, called molecules. When, therefore, we powder the sulphur, we merely separate the molecules from each other, Molecules consisting of one kind of atoms are called elemental molecules; those containing more than one kind are called compound molecules. Atoms and molecules are believed to be in a constant state of vibration, the rapidity of which increases with increase of temperature, and is, there- fore, more rapid in the liquid than in the solid state, and still more rapid in the gaseous condition. This is known as the kinetic theory. When a solid becomes a liquid or a liquid becomes a gas, or the reverse occurs, the molecules are not changed, but merely separated from one another. Hence the atoms in sulphur vapor are as hard and solid as those of solid sulphur, but in the vapor the pairs or molecules which they form are separated by greater distances than in the case of the solid. The force which holds atoms together and forms them into molecules is a chemical force, and is called chemical affinity. Any number of molecules of the same kind may be held together in a mass ; the force that does this is called cohesion. 12 inorganic chemistry. Atomic Weights.—Chemists have never been able to isolate or render visible atoms or molecules. Nevertheless, the progress of chemical research has developed some general principles. 1st. That the atoms of each element have a constant and definite weight. 2d. That the atom of hydrogen is the lightest of all. 3d. That combination takes place among atoms under the action of chemical affinity. Starting with the first two principles, numbers have been obtained which are supposed to represent the weight of each atom compared to the atom of hydrogen. These numbers are called ATOMIC weights. In any compound the sum of all the atomic weights is called the molecular weight. Thus, sulphuric acid is H2S04; its molecular weight is 98. H2= 2(2X1) S =32 04 = 64 (16 X 4) 98 NOTATION. A chemical symbol is an abbreviation of the name of an element; in most cases an initial letter is used, as C for carbon, P for phosphorus. As some elements have names beginning with the same letter, proper distinc- tion is obtained by assigning the single letter to the most common, and attaching small letters to the other initials. Thus, C stands for carbon, Ca for Calcium, CI for chlorine, Cd for cadmium. Certain elements have different names in different languages, and for these the symbol is formed from the Latin name. Iron, for instance, is represented by Fe [ferrum); lead by Pb [plumbum); silver by Ag (argentum); potassium by K [kaliuni). To express combination between elements—in other words, to express the composition of a compound body or of a molecule—the symbols are to be written together like the letters of a word. Such a collection of symbols is called a formula. The symbol, however, not only represents the element, but one atom of it. The expression CaO not only shows a compound consisting of calcium and oxygen, but also indicates that it contains a single atom of each ele- ment. Ca02 shows that two atoms of oxygen are present and one of cal- cium. In writing these expressions certain rules are followed:— NOMENCLATURE. 13 1st. To multiply any single atom, a small number is attached to the lower right hand, as seen above, where 02 indicates two of oxygen. The for- mula C2H402 shows a combination consisting of two atoms of carbon, four of hydrogen and two of oxygen. 2d. To multiply several atoms by the same number, we put a large figure in front. Thus 2HCIO is equal to H2C1202; that is, the large figure mul- tiplies the whole expression. 3d. To multiply a portion of an expression, several methods are in use. We may enclose the part to be multiplied in parenthesis, and attach the proper number to the right-hand corner. Ba(N03)2, for instance, equals BaN206; C6H8(N02)205 equals C6H8(N204)05. The effect of the small figure is limited to the part within the parenthesis. This method is especially adapted to multiplying symbols in the middle or at the end of a formula. To multiply the symbols at the beginning of a formula, we usually point off or punctuate the part to be affected, and place a large figure in front. Some irregularity prevails as to the particular sign used, the comma and semicolon both being employed. It is sufficient for the student to bear in mind that a punctuation mark or plus sign occurring in a formula will stop the multiplying effect of the large figure at the beginning of the expression. For instance, 2C2H5, H2N is equal to C4H10H2N; similarly, in 2FeS04 -f- HC1 the letters following the plus sign are not affected by the figure 2. If we wish to carry the multiplying effect to the end of the expression, we enclose it in parentheses; thus, 2(FeS04 -\- HC1). Here all the letters are equally influenced. Since the symbol of each element represents one atom, it follows that every symbol carries with it an idea of quantity. If we write HC1, the meaning is not merely that hydrogen and chlorine are in combination, but that the amounts by weight are in the proportion of the atomic weights; i. e., 1 (atomic weight H) to 35.4 (atomic weight CI). When the symbol is multiplied, the weight is also multiplied. For instance, H20 represents 2 parts by weight of H to 16 of O; HgCl2 represent 200 parts of mercury and 70.8 (35.4 X 2) parts of chlorine. NOMENCLATURE. The names of chemical compounds are regulated by a system which depends essentially upon the employment of certain terminations. In the old division of the elements into metals and non-metals the metals were usually distinguished by the termination " urn." A change of this termination into " a " indicated combination with oxygen. Potassium (K) 14 INORGANIC CHEMISTRY. becomes by oxidation, potassa (K20); sodium (Na) becomes soda (Na20); magnesium (Mg) becomes magnesia (MgO). As the names of many of the common metals do not end in " urn " unless the objectionable Latin name is used, this rule is only of limited application. The tendency of the modern nomenclature is to make but little change in the names of the sub- stances called metals, and the terminations about to be presented are not usually attached to bodies ending in " um," or those which we commonly call metals, such as iron, silver and zinc. Chemical compounds which contain only two elements are called binary compounds. They are usually named by joining the names of the elements present and attaching to one of them the termination " ide." This termina- tion may be conveniently regarded as an equivalent of the phrase " nothing else;" that is, wherever it occurs it indicates that nothing else is present except what is expressly mentioned. Potassium vAide, for instance, can contain nothing else but potassium and iodine; copper sulpha can contain nothing but copper and sulphur. PbO .... Lead oxide. NaCl .... Sodium ch\oxide. AgBr .... Silver bromide. The syllable " ide " is usually attached to the members of the oxygen, chlorine, nitrogen and carbon groups, and preferably to those of the first two groups. Thus, a compound of iron and carbon is called iron carbide, but a compound of carbon and chlorine is called carbon chloride. In many books, especially in older works, the word " of" will be found frequently used in the names of compounds. Instead of copper sulphide, we see sulphide of copper, iodide of potassium for potassium iodide. This system was introduced into chemistry by an original mistranslation of French phrases in which the word " de " occurred. As elements may combine in several proportions, forming several differ- ent compounds, this termination ide does not suffice. The bodies Cu20 and CuO are both properly called copper oxide, because they contain only copper and oxygen, but they are different. In the same way, S02 and S03 are both sulphur oxides. The distinction is made by prefixes. Cu20 . . . Copper suboxide. CuO so2 S03 cci4 PCL " ;#0«oxide (formerly proto was used). Sulphur afroxide (formerly dent or bin was used). " /r/oxide (also teroxide). Carbon tetrachloride or quadrichloride. Phosphorus pentachloride. NOMENCLATURE. 15 Sub generally indicates deficiency; that is, that the quantity of the element to which it is attached is less than it should be. We apply the term sub especially to compounds in which a member of the oxygen or chlorine group is deficient in amount. Pb2Cl, Zn3I2, Cu40 would be sub- compounds. Some elements form compounds in which the proportion is as I to 1^, but as fractions are not allowed in formulae, the whole expression is multi- plied by 2, which gives the proportion 2 to 3. FeOjJ^ becomes, there- fore, Fe203. These are called sesqui compounds, and the above expression is iron sesquioxide. The word sesqui means one and a half, and conveys the idea that the relation between the two elements is as 1 to 1^ (2 to 3). There is no uniform method for giving names to compounds containing more than two elements. Sometimes the system is the same as that just given; all the elements are mentioned and the termination " ide" is attached. Thus KHO is potassium hydroxide, NaHO is sodium hydroxide. In other cases a portion of the compound is included under a group name, and this is joined with the names of the other elements according to the above rule. Thus KCN is not called potassium carbo-nitride, but the CN is called cyanogen, and the entire compound is called potassium cyanide. Among the compounds containing three elements are those which we call salts. Salts are formed by the action of acids upon certain elements or their oxides. If we put zinc or zinc oxide into sulphuric acid, we get a zinc salt; in this case zinc sulphate: also by direct union of many oxides; for instance, when calcium oxide, CaO, acts upon carbon dioxide, C02, we get calcium carbonate, CaC03, which is a salt. Most salts contain three elements, of which oxygen is one, and the names are made by joining the names of the other two elements and adding to them certain syllables which not only indicate the presence of oxygen, but also partly the amount. These syllables are ate and ite. The former indicates the greater quantity of oxygen. The potassium sulphate and potassium sulphzte both contain oxygen, but the former (sulphate) contains the more oxygen. Sodium nitrate and sodium nitr/te contain the same elements, but their composition is NaN03 and NaN02, respectively. It has been pointed out that the syllable ide could be regarded as equiva- lent to the phrase " nothing else." In the same manner, the syllables ate and ite are to be regarded as meaning " something else," generally oxygen. Thus, while in sodium sulphzVte but two elements are present, sodium sulphate and sulphate will contain three. These two terminations are not sufficient. Potassium, chlorine and oxy- gen unite in four different proportions, forming KC104, KC103, KC102, 16 INORGANIC CHEMISTRY. KCIO. In such cases the important or most common compound is distin- guished by the termination ate, and the one containing the next lower amount of oxygen by the termination ite. The other compounds are indicated by the use of certain extra syllables, hypo and hyper, the latter now generally abbreviated to "per." The significance and use of these syllables are shown in the following table:— KC104.....Potassium perchlorate. KC103..... " chlorate. KC102..... " chlorite. KCIO..... " hypochlorite. Na2S04 . . . Sodium sulphate. NajjSOg .... " sulphite. Na2S02 .... " hyposulphite. When hydrogen is present in such compounds, a different method is adopted. Thus we have HC104, HC103, HC102, HCIO, and these might be called hydrogen perchlorate, hydrogen chlorate, etc. The usual method is to drop the word hydrogen, change the termination ate into ic, the termination ite into ous, and add the word acid. HC104.....PerchlonV acid. HClOj.....ChlonV acid. HC102.....Ch\orous acid. HCIO.....Hypochloro«j acid. The prefixes are retained without change, and the syllable ic corresponds to ate, and the syllable ous to ite. Potassium sulphate") K2S04 / Potassium sulphite "t K2S03 / Potassium hyposulphite "1 K2S02 / ™-,oo~__Ac * f Sulphuric acid corresponds to -< r„ <,„ u ( Sulphurous acid t H2SOs „ \ Hyposulphurous acid \ H2S02 Sometimes the hydrogen is only partly replaced by another element, and the body intermediate between the acids and the salts. Thus KHSO, is at once a potassium and a hydrogen compound. It is called acid potassium sulphate. The word acid calls attention to the hydrogen. These acid salts are not unfrequently called £/-salts. Acid potassium sulphate is known in commerce as potassium bisulphate; the corresponding acid carbonate, KHCO3, as bicarbonate. The use of the syllable bi is improper. In a LAWS OF COMBINATION. 17 few compounds of exceptional composition the title is used for want of a better one. K2Cr20T, for instance, is called potassium bichromate. It is not properly so called; it does not contain two molecules of chromic acid. The terminations "ous" and " ic" are employed with elements forming two sets of compounds. Iron forms two chlorides, two iodides, two sulphides,etc., as follows:— FeO FeCl2 FeSOt Ferwwj salts. Fe2Oa Fe2Cl6 Fe2(SOJ3 FernV " These terminations do not indicate the amount of the element to which they are attached, but of the other substance; ous, as usual, means less than ic. LAWS OF COMBINATION. The great law of chemistry is the law of constant proportion. Each chemical compound is definite in its nature, the proportion of its constituents being constant. Water, for instance, when pure, always consists of n.n per cent, of hydrogen and 88.89 Per cent, of oxygen. ■ Elements, however, are not limited to one proportion of combination, but in each proportion a different body is produced. Thus, there is a compound containing about six per cent, of hydrogen and ninety-four per cent, of oxygen. It is, however, very different from water. So, also, there are five compounds of nitrogen and oxygen, all different bodies. When the pro- portions present in different compounds are expressed in terms of atomic weight, it is generally found that a simple multiple relation exists. For instance, the two compounds of hydrogen and oxygen have the formula, respectively, H20......Water. H202......Hydrogen dioxide. The five compounds of nitrogen and oxygen are N20, NO, N203, N02, N205. This fact has given rise to a second law, or rather rule, called the law of multiple proportion, viz., When elements combine in more than one propor- tion, the higher proportions are simple multiples of the lower. The same simplicity and constancy of proportion is observed in the combination of compound bodies. The combining weight of a compound body equals the sum of the molecular weight of its constituents. Thus, lime consists of calcium and oxygen—CaO. The combining weight is Ca = 40 0 = 16 .-. CaO = 56. When lime is mixed with water the two 18 INORGANIC CHEMISTRY. bodies combine in definite proportions. H2 = 2 O = 16 .•. H20 = 18. 56 and 18 are respectively the molecular weights of lime and water, and it is in this proportion they combine ; 56 parts by weight of lime with 18 parts by weight of water, forming 74 parts of slacked lime— CaO + H20 = CaH202. VALENCY. * Elements, as above noted, may combine in several proportions. When compounds containing the same elements are compared, we generally find one proportion which seems to be the most natural; it is either most fre- quently or easily produced, or it is the one least liable to change. Hydro- gen and oxygen combine in two proportions, thus :— xl PT hJ WigU o } = H2°- Hydrogen monoxide. 2 parts by weight H | = R ^ Hydrogen dioxide These bodies are very different. The first is water, a compound not liable to decompose. The second substance is difficult to prepare and to preserve; it is liable to explode. We may suppose, therefore, that the normal pro- portion of combination between H and O is H20. Carbon forms with oxygen two well-marked compounds, CO and C02. CO is formed when carbon is burned in a deficient supply of oxygen, but C02 is formed when the carbon burns under natural conditions in a free draft of air or oxygen. CO, besides, shows a tendency to take up more oxygen, especially when heated, and it will combine with chlorine, even at ordinary temperatures. C02, on the other hand, shows no tendency to combine with either oxygen or chlorine. The atom of hydrogen has been taken as a point of comparison, and each element compared according to the number of hydrogen atoms with which it forms the most permanent combination. For instance, we find compounds with hydrogen as follows :— CI combines with one H, forming HC1. Br " " H, ' HBr. 0 " two H, ' H20. S " " H, ' H2S. N " three H, ' H3N. As " " H, ' H3As. C " four H, H4C. VALENCY. 19 These are not the only compounds that can be formed from these ele- ments, but they are those which show only a slight tendency either to take new atoms or give up what they already possess. The number of hydrogen atoms with which any element combines is called its valency. The term atomicity was formerly used but is not now much employed. Degrees of valency are indicated by names and Roman numerals, the latter being placed to the upper right hand of the symbol. I indicates a monad (monatomic or monovalent). II " a dyad (diatomic or bivalent). HI " a triad (triatomic or trivalent). IV " a tetrad (tetratomic or tetravalent). V " . a pentad (pentatomic or pentivalent). VI " a hexad (hexatomic or hexivalent). VII " a heptad (heptatomic or heptivalent). Valency has nothing to do with the energy or activity of the element. It is a measure of capacity only. Bodies of high valency are often of weak affinity, while some of the strongest chemical agents are of low valency. Chlorine has ordinarily only one-third the valency of nitrogen, but it is much viore active when free. Degrees of valency are determined by a study of the proportions in which bodies combine; a knowledge of the valency of the elements is a key to the composition of all their important and more permanent compounds. The following gives the valency of the principal groups of elements:— Monad,—potassium and chlorine groups. Dyad,—oxygen, iron, calcium, zinc groups, and frequently the iron group. Triad and pentad,—nitrogen group. Tetrad, carbon group and sometimes the iron group. When elements are combined in such proportion that their valencies are equalized, the compounds are said to be saturated. This meaning must be distinguished from the more common one, viz., that a body has dissolved or absorbed as much of any substance as it can take up. In this latter sense we speak of saturated solutions, meaning solutions which contain as much of any substance as can be dissolved. Taking the monad group, for instance, the members being equal to one atom of H, they are equal to each other. Hence, K and CI will combine in equal number of atoms, forming KCl, potassium chloride. Similarly, we will have NaBr, Agl, etc. The dyad elements have twice the com- 20 INORGANIC CHEMISTRY. bining capacity of monads; we will find, therefore, that the compound of sodium and oxygen will be Na20. The combination between triad antimony and chlorine will be SbCl3; between tetrad carbon and dyad oxygen will be C02; between pentad nitrogen and dyad oxygen N205. The degrees of valency given above are not invariable. The circumstances under which the variation takes place cannot be very well defined; but the extent or rate of variation is by a simple law, to which only a few exceptions need be made. When an element changes its valency, either increasing or diminishing, the change is by two degrees at a time. Elements of even valency remain even, passing, for instance, from hexads to tetrads, and finally to dyads, or the reverse; elements of uneven valency remain uneven, passing from pentads to triads and monads, and the reverse. Certain elements seem to be exceptional, but, by a supposition, we preserve the application of the law. These bodies are supposed to have the prop- erty of combining with themselves in such a manner as to form double atoms, possessing a valency greater than either atom singly, but less than the sum of the valencies of the two atoms. Iron, generally a dyad, becomes in certain compounds a tetrad, but two atoms of iron unite and form a double atom, which then forms compounds with other elements. A short reflection will show that this double atom, formed from two atoms each having a capacity of four, will have a power of six, one degree of valency in each atom being saturated. For cases of varying valency, the terminations ous and ic are employed, ous indicating the lower degree and ic the higher. We have in this way manganous (lower valency) and manganic (higher valency) salts, ferrous (dyad) and ferric (hexad) compounds. In the terminations of the names of acids the same principle is carried out, sulphurous acid being the com- pound in which sulphur has a lower (tetrad) valency; sulphuric acid one in which sulphur has a higher (hexad) power. We not only employ a knowledge of valency for determining the propor- tion of combinations between any two elements, but starting with any molecule, we may by substitution obtain the formula of any derivative of that molecule. Thus the body called nitric acid, forms derivatives called nitrates, in which the hydrogen of the acid is replaced by other positives. Suppose we wish to write the formula of potassium nitrate; the reasoning would be as follows: Nitric acid is HN03—potassium is a monad; one atom of potassium will substitute the atom of hydrogen, and the formula is KN03. By the same reasoning the formula of copper sulphate may be deduced. Sulphuric acid is H2S04, copper is a dyad; one atom of copper VALENCY. 21 will displace two of hydrogen; therefore, CuS04. When the standard formula contains too small an amount of hydrogen, we must multiply the expression by some whole number. For instance, the formula of copper nitrate will be deduced in this manner: Nitric acid is HN03, copper is a dyad; copper will therefore replace the hydrogen of two molecules of nitric acid; hence, Cu(N03)2 or CuN206. If we take one or more atoms from a saturated compound, we leave the compound unsaturated to a degree equal to the hydrogen atoms to which the removed atoms correspond. The molecule H4C is saturated. The molecule H3C can take up one H or its equivalent, and is therefore a monad ; H2C can take up H2, and is therefore a dyad; and so on. The valency of any molecule can thus be obtained by finding how much hydro- gen is required to form a saturated compound. By this method we deter- mine that HO is a monad, for it requires but one atom of H to complete the molecule; C03 is a dyad, for it requires H2 to form the saturated com- pound H2C03; P04 is a triad, for it forms H3P04. (See section on Radicles.) Graphic Formula.—A convenient and much-used method of indicating valencies is by graphic formula. These consist of the symbol of each element, with bonds or prolongations the same in number as the degrees of valency. Taking some common elements as examples, we have monad dyad triad tetrad pentad I I I K— —O— — P— —C— =N= I These bonds may be attached in any position or direction as long as the proper number is used. Carbon, for instance, may be written as above, or C= — C= =C= =C or in any other way, provided four bonds are present. In the practical application of this notation we link together the bonds of the different elements, and when all the points are joined the compound is complete and is a saturated molecule. Two bonds of one atom, how- ever, can never be attached to a single bond of another atom. The follow- ing are examples of some common compounds written graphically :— H—CI; H—O—H; H—N~[J; 0=C=0. We may also indicate unsaturated molecules. Thus, 0=C= shows that carbon monoxide is a body having two degrees of valency unsatisfied; 22 INORGANIC CHEMISTRY. 0=C=S that two atoms of chlorine have combined and satisfied this free valency. The nature of the change by which the iron atom passes from a dyad to a hexad condition can be very well shown by this method. Dyad iron, graphically represented, would be Fe=, in which two bonds have dis- appeared, leaving two still active. In the higher degree of valency (tetrad) the condition is —Fe—Fe—, one bond of each atom having combined and I I linked the two in chemical union. Ferric oxide and ferric chloride would be 0 0 CI CI Fe—Fe CI—Fe—Fe—CI ELECTRICAL RELATIONS OF THE ELEMENTS. Electrical excitement exhibits two conditions, called respectively positive and negative, which are produced in any apparatus developing electricity. The points at which the electrical excitement is manifested—for instance, the ends of the wires of a battery—are called the poles. The positive pole, also called the anode, is distinguished by the sign -)-, and the negative, also called the kathode, by the sign —. Two bodies differently electrified will attract each other, but if charged with the same kind of electricity will repel. The law is generally expressed as follows: Like electricities repel; unlike attract. These principles have been applied to the determination of some import- ant relations between elements. A current of electricity decomposes many compound bodies; some elements appearing at the positive pole, and others at the negative. Thus, potassium will be liberated in contact with the surface negatively charged, and oxygen in contact with the positive surface. This will be the invariable result with these elements, no matter what compounds be taken for the experiment, but with many other elements the effect will depend upon the nature of the compound. With H2S the sulphur will appear at the positive pole; with S02, at the negative. Since unlike electricities attract, it follows that elements which go to the positive side must be negative, and those at the negative side must be posi- REACTIONS. 23 tive. Very frequently we use the term "electro" in this connection; thus we say, zinc is electro-positive; chlorine is electro-negative. A body is not absolutely positive nor absolutely negative, but is simply more positive or more negative than some other substance. Nevertheless, as the list of elements is limited, we will have two bodies which, by their high affinities, will stand at the extremes of the scale, one being negative, the other positive. Leaving out of consideration some rare elements, we may place potassium as the most positive, oxygen as the most negative. The applications of the above principles will be presented in connection with the discussion of Radicles and Reactions. REACTIONS. Chemical symbols are employed not only to show the composition of bodies, but also to show exactly the nature of the chemical changes which occur when different bodies are brought in contact. When so used, the ex- pression is called a reaction. Certain compounds, which are much used for producing reactions, are called reagents, though strictly all the sub- stances present take equal part in a reaction. When we pour vinegar upon a marble table, we say, in ordinary phrase, that the marble is corroded, but, in fact, the vinegar is equally acted upon, both substances are changed in composition, both are rendered unfit for their original uses; in other words they have not only acted, they have reacted, and are therefore both reagents. A reaction is substantially an expression of the results of an experiment, and, when correctly written, gives us the proportion in which bodies are to be used and the proportion of the resulting substances. Speaking abso- lutely, we can never be sure of the correctness of any reaction until we make the experiment and analyze the result; but the progress of chemistry has made known certain laws of change, which enable us to predict, or infer, many results without the necessity of actual observation. Every now and then, however, the analogy fails, and experiment disappoints the sug- gestions of theory. Reactions are written by placing in proper proportion and connected by -f- signs the formulae of the bodies concerned, then writing the sign = and following this by the formulae of the resulting bodies. For instance, AgN03 + HC1 = AgCl + HN03 expresses that on bringing together silver nitrate and hydrochloric acid, a chemical change occurs by which silver chloride and nitric acid are pro- 24 INORGANIC CHEMISTRY. duced. Students find, in regard to writing reactions, three difficulties : 1st. To know whether a given change will take place. 2d. To know the quan- tities of the bodies to be used. 3d. To know the nature of the resulting bodies. These difficulties may be taken up in order. 1st. In the simplest cases, the nature of the reaction will be determined by the affinities of the elements as governed by their electrical relations, the change taking place in such a way that the element .having the stronger electric affinity will drive out and supplant the element of similar but weaker affinity. We find that when chlorine acts upon the bromides they are decomposed, the bromine being expelled, and that bromine, in turn, expels iodine from com- bination. Therefore, such reactions as ^ KBr + Q = KCl + Br KI + Br = KBr + I, are simply illustrations of the general electrical relations of elements con- cerned. If these affinities were the only active causes of chemical change, the subject would be quite simple, but circumstances may modify the play of affinities, so as to produce an endless variety of chemical action. All the modifying influences are not yet known, but some of them are under- stood, and are of importance. [a) Insolubility.—When in any liquid we bring together substances which are capable of forming a body insoluble in the liquid, that insoluble compound will be produced in spite of the general relations of affinities. This influence of insolubility is the basis of a large number of tests and other chemical operations. When the formation of the insoluble compound would require a powerful chemical agent to be set free, the change will not take place, unless, of course, the added substance is stronger than the one to be liberated. Car- bonic acid forms with calcium a body quite insoluble in water, but this body cannot be formed by passing carbonic acid into calcium sulphate. The reason is shown at once by examining the conditions of the experi- ment. The reaction would have to be CaS04 + H2C03 = CaC03 (insolu- ble) 4- H2S04, that is, sulphuric acid would be set free. The affinity of H2C03 is, under ordinary conditions, so much below that of H2S04 that the former will not drive out the latter. The condition becomes.changed if we assist the action of the carbonic acid by some substance which has an affinity for sulphuric acid and will prevent it being set free. CaSO -f- Na2C03 will produce immediate action, resulting in CaC03 -f- Na^SO . This reaction illustrates a common method of keeping the powerful affini- ties in abeyance, and thus allowing secondary influences full play. Some REACTIONS. 25 of the arsenic tests show the principle strikingly. Arsenious acid added to CuS04 produces no action, because the affinity of the S04 is too strong, but by adding a little alkali, the strong affinity this has for S04 assists in breaking up the copper sulphate and immediately a precipitate of copper arsenite falls. [b) Volatility.—This is the second influence that disturbs ordinary affinities. If a body is capable of being converted into a gas, this fact will diminish its chemical power; fixed substances that have ordinarily less affinity will drive it out of combination. Boric acid, for instance, is one of the weak acids, yet at a red heat it will drive out even sulphuric acid. The cause is, in the main, that at this temperature sulphuric acid is volatile, while boric acid is fixed. The ease with which hydrogen is driven out of combination may be regarded as due to its volatility, it being a gas even at low tempera- tures. (c) Mass.—Sometimes chemical action seems to be governed by the quantity of the substance present. If we pass water vapor over red-hot iron, iron oxide is formed and hydrogen is set free; if we pass the hydrogen back over the iron oxide, steam is formed and iron set free. In the first case, the water is in excess and exerts an oxidizing influence ; in the second, the hydrogen is in excess, and exerts a deoxidizing influence. The effect of mass is indefinite and uncertain, and need not enter into the ordinary working of reactions. It will be seen to be a deduction from these statements that no substance can be set down as absolutely the strongest in affinity. Chemists cannot determine, for instance, what is the strongest acid or the strongest alkali, except under specified conditions. 2d. The proportion in which bodies react is determined by their valencies. Let it be required to write the reaction between mercuric chloride and potassium iodide. The formulte are HgCl2 and KI, but the bodies will not react in this proportion, for the Hg will require I2 and Cl2 will require K2. The proper reaction is HgCl2 4- 2KI = HgT2 + 2KCI. In the same way, antimony sulphide and hydrochloric acid can only act upon each other in the ratio Sb2S3 4- 6HC1 because Sb being a triad, Sb2 will combine with Cl6, and S being a dyad, S3 will require H6. 3d. If a chemical change occurs when two given substances are brought in contact, the nature of it will depend principally upon the electrical rela- tions of the elements concerned. In the reaction HgCl2 4- H2S, the only possible result is the combination of S with Hg and H with CI, as is shown 3 26 INORGANIC CHEMISTRY. + - +T at once by placing the proper signs over the elements, Hg Cl2 H2 S. + +-- Such a combination as Hg H2 or Cl2 S could not take place, since it requires like electricities to attract, which is against the rule. In beginning with reactions, the student will do well to place the proper signs over each element, and these will be a useful guide and control. When acids or salts, containing three elements, are part of the reaction, the plus sign is put over the hydrogen or the metal, and the negative sign over the oxygen and other element, thus:— 4- - +- +- 4- - Ba(N03)2 4- K2S04 = BaS04 4- 2KNO3. The placing of the single sign over the two elements is simply an evidence of the fact that in ordinary reactions these two elements act as a single element. The following formulae will further illustrate the general principle:— + — + - +- 4- — Ag N03 -f Na CI = Ag CI 4- Na N03 + - — 4- — - H20 + Cl2 = H2Cl2 + 0 + - 4-4-- +- +- + — Ba Cl2 + K H S04 = Ba S04 4- K CI 4- H CI In the last reaction, the electro-positives K and H may seem to be in union, but this is not the case. Each is independently united to the S04, which is a dyad. The formula might be written— KSO RbU4. RADICLES. A radicle is any group of atoms having unsatisfied valency, the number of these unsatisfied degrees being the valency of the radicle. The follow- ing formulae illustrate the principle. The degrees outside the parentheses indicate in each case the valency of the radicle, being, of course, the differ- ence between the valencies of the constituent atoms:— / v n \ i / v n \ I / it ni\ 1 / it n\ n / i n\ i / i iv\ m (no3) InoJ (cn) (co) (ho) (hc) The electrical relations of a radicle are generally determined by the elec- trical character of the preponderating valency, but not invariably. While RADICLES. 27 the combining capacity and general functions are substantially dependent on the unsaturated valency, yet, in chemical combinations, the whole molecule takes part, and hence the electrical character is influenced by that of each atom present. Thus in (n H*)' we might m^er ^at l^e nitrogen valency would only give to the radicle indifferent or intermediate electrical relations, but experiment shows that this is a group having distinctly positive affini- ties ; the four atoms of positive hydrogen, though insufficient to saturate all of the nitrogen valency, yet impress on the molecule their function. In many cases the influence of the preponderating valency is more decided. Thus in (jJq)' the oxygen valency is in excess, and the radicle is negative. The compounds of carbon show very well the principle on which the valency of a radicle depends:— H C......................Saturated H C......................Monad. H2C......................Dyad. H C......................Triad. q ......................Tetrad. The last is the free element which might be regarded as the final radicle, so that we may speak of both elemental and compound radicles, but the term is usually limited to the latter signification. The following formulae give the compositions, valencies and names of some important radicles :— NH, ...........Ammonium N H2 ...........Amidogen . HO ...........Hydroxyl . . ..........Hydrosulphyl .......... Cyanogen ..........Methyl . NO" .....•.....Nitrosyl gb O ...........Antimonyl CO ...........Carbonyl i n HS IV III CN I IV H C Monad. Dyad. 28 INORGANIC CHEMISTRY. ACIDS, BASES AND SALTS. Acids are compounds in which hydrogen is united directly either to strongly negative elements, or to positive elements, which are at the sauie time united to some member of the oxygen group. Several classes of acids may, therefore, be distinguished. Hydrogen acids—commonly called hydro-acids— Oxygen acids HC1 HBr HI HF H2S04 HN03 H3P04 H2COa HCIO, Hydrochloric acid. Hydrobromic acid. Hydriodic acid. Hydrofluoric acid. Sulphuric acid. Nitric acid. Phosphoric acid. Carbonic acid. Chloric acid. Experiment shows that in each of these oxygen acids, the hydrogen is in more direct relation with certain oxygen atoms than with the rest of the molecule, so that they may be formulated as follows:— (HO)2S02 (HO)N02 (HO)3PO (HO)2CO (HO)C102 It will be seen that all the hydrogen is in the form of hydroxyl. Hydrogen which is not in this condition in a molecule is not easily replaceable by a positive element, unless united to a strongly negative radicle. Thus in HC1, the hydrogen is easily replaceable by a positive, but not in NH3. The two conditions of hydrogen may co-exist in a molecule. In hypophosphorous acid H3P02 experiment shows that only one hydrogen atom is easily replaceable, and the arrangement is considered to be as follows:— H H—O—P—H II O Only one hydrogen atom is directly united to a strongly negative element. Such differences in the position and function of hydrogen in the same molecule are unusual in the inorganic acids, which generally have all their hydrogen in either the hydroxyl position or in some similar relation, but nearly all organic acids contain hydrogen which is not replaceable. ACIDS, BASES AND SALTS. 29 In sulphurous acid, H2S03 experiment shows that we probably have the arrangement H—S—O—O—H O Here both hydrogen atoms are replaceable, because both are directly united to a member of the oxygen group, that is, to strongly negative elements. In sulphocarbonic acid, H2CS3, in which sulphur takes the place of oxygen, the arrangement is as follows: (HS)2CS; sulphur, selenium and tellurium may in this manner take the place of oxygen in the molecule and render the hydrogen replaceable. When the molecule contains bodies of high positive character, the power of replacing the hydrogen by other positives does not exist, unless several molecules of oxygen (or S, Se or Te) are also present. It appears then* that as the proportion of oxygen is increased in any molecule, without other change, its acid character will be gradually developed. Thus Cr(HO)2 possesses no acid character, but if two atoms of oxygen be added to the chromium, making (H0)2Cr02, that is, H2Cr04, a well marked acid, chromic acid, is produced. It is then, according to the number and posi- tion of the negative elements in any molecule that the function of the hydrogen is determined. When strongly positive elements are present, either without negatives or with only relatively few atoms of them, the hydrogen is not easily replaceable by positives, the body is not an acid, but has power to interact with acids and neutralize them. Thus the above mentioned compound, Cr(HO)2, will dissolve easily in sulphuric acid and neutralize it, that is, take away the characteristic properties of the acid, the sour taste, effect on organic colors (see below), and general chemical activity. Substances that act in this manner are called bases. The action in the case of chromous hydroxide and sulphuric acid would be thus represented:— Cr(HO)2 4- H2S04 = CrS04 4- 2H20. Further instances are as follows:— NaHO 4- HC1 = NaCl + H,0. NaHO 4- H2S04' = NaHS04 4- H20. 2NaHO 4- H2S04 = Na;S04 + 2H20. KHO 4- HN03 = KN03 4- H20. Cu(HO)2 4- H2S04 = CuS04 4- 2H20. Bi(HO)3 4- 3HCI = BiCl3 + 3H20. Fe2(H0)6 + 3HaS04 = Fe2(S04)s 4- 3H20. 30 INORGANIC CHEMISTRY. The bodies NaCl, NaHS04, etc., are called salts. A salt may, therefore, be defined as the result of the interaction of an acid with a base. Since the function of the base in these reactions depends essentially on the strongly positive element, it is not necessary to have it in association with hydroxyl. The formation of salts may take place by the action of acids upon oxides, upon the elements themselves, and also upon compounds con- taining weaker acid radicles than those existing in the acid employed. Zinc sulphate, for instance, may be made by any of the following methods :— Zn 4- H2S04 = ZnS04 4- H2. ZnO 4- H2S04 = ZnS04 4- H20. Zn(HO)2 4- H2S04 = ZnS04 4- 2H20. ZnC03 4- H2S04 = ZnS04 4- H20 4- C02. Theoretically, therefore, and frequently practically, there may be many methods of producing a salt, but in many cases the affinity of the acid radicle is not sufficient to bring about the change, unless the positive is either in the form of oxide or hydroxide. Thus the reaction— Ag 4- HC1 = AgCl 4- H will not occur, but either AgHO 4- HC1 = AgCl + H20, or Ag20 + 2HC1 = AgCl 4- 2H20 will occur. Intimately connected with this subject is the meaning of thf terms acid, alkaline and neutral, as applied to the conditions of substances. If we add a drop of sulphuric acid to a solution of the coloring matter of purple cabbage, it becomes red; by the addition of a small amount of soda the color will be restored, and by further addition changed to green. The soda is a base; it has interacted with the acid and deprived it of its chemical activity. By this combination the soda has also been neutralized, and it is only by adding it in excess, that we can get its specific action on the color. Litmus is a red color much used for these tests. It becomes blue on the addition of a base, and has the red color restored on the addition of an acid. It is usually sold in the blue condition, and is used either in solution in water or in the form of litmus paper— strips of paper soaked in the solution and dried. A number of artificial colors from coal-tar products are now used as substitutes for litmus. Among these are:— Phenolphthalein—red when alkaline, nearly colorless when acid. Congo red—red when alkaline, blue when acid. ACIDS, BASES AND SALTS. 31 Lakmoid—similar changes to litmus. Phenacetolin—pale yellow with acids, pink with alkalies. These color reactions are of importance in practical chemical operations, but they have little value in determining the theoretical relations between acids, bases and salts since there are substances which are theoretically acids, yet act on the colors as if alkaline, and the reverse. The number of atoms of replaceable hydrogen in an acid determines its basicity. HN03 having one replaceable hydrogen atom, is monohzsxc. H2S04 " two " " " " oYbasic. H3P04 " three " " " " ^'basic. H4Si04 " four " " " " tetrabzsic. An acid like hypophosphorous, H3P02, is not tribasic, therefore, but monobasic. Similar phrases are applied to bases but more rarely; thus calcium hydroxide, Ca(HO)2, having the power to take up two molecules of any monobasic acid, might be called a di-acid base. The radicle obtained by deducting all the replaceable hydrogen from an acid is sometimes called the residue of the acid. S04, for instance, is the residue of sulphuric acid, N03 the residue of nitric acid. The acid radicle proper is the body obtained by deducting all the hydroxyl or hydrosulphyl, etc., from the acid. S02 is the radicle proper of sulphuric acid. This distinction in nomenclature is convenient in expressing some of the reactions of these acids. Salts may be divided into four classes:— Normal salts, in which the hydrogen of the acid is replaced by a single element, according to its valencies. The acids themselves are nor- mal salts of hydrogen:— N32CS3..............Sodium sulphocarbonate. KN03..............Potassium nitrate. Mixed salts, in which two or more positives are present. When some replaceable hydrogen remains, the body is usually called an acid salt:— HKC03.............Acid potassium carbonate. KNaC4H406...........Sodio-potassium tartrate. Double salts, in which two complete salts of either of the above classes unite to form a definite compound, which is generally distinctly crystalline:— 32 INORGANIC chemistry. K2S04, A12(S04)3.......Potassium aluminum sulphate. FeS04, (NH4)2S04.......Ammonium ferrous sulphate. 2KC1, PtCl4.....i . . . . Potassium platinum chloride. Oxy salts (sometimes called basic salts or sub salts) in which oxygen takes the place of one or more of the acid radicles:— BiN030..............Bismuth oxynitrate. SbOCl...............Antimony oxychloride. VOLUME COMBINATION. If we weigh equal volumes of the elements in the state of gas, we find that their relative weights will, with a few exceptions, be in exact propor- tion to their atomic weights. For instance, a vessel which holds I grain of hydrogen (about 47 cubic inches) will hold the following quantities of other elements, it being understood that all the bodies are in the state of gas and at the same temperature and pressure :— Element. Atomic Weight. Wt. of vol.. , equal to 1 vol. of H. 0 16 16 S 32 32 CI 35-4 35-5 I 127 127 Br 80 80 Some of the elements cannot be converted into vapor, and consequently cannot be compared on this system. Among these are carbon, silicon and many of the common metals. These practically resist the action of the highest temperature which can be used in such experiments. A few ele- ments show results which are exceptional; among these are— Element. As P Atomic Weight. 75 3i Wt. of vol., equal to 1 vol. of H. 150 62 Hg 200 IOO In the case of phosphorus and arsenic the weight is twice as great as analogy would require; in the case of mercury, half as great. The following law has been established by mathematical and physical investigation : Equal volumes of elementary gases contain equal numbers of molecules. The relative weight of the atoms of each element may be determined by volume combination. 33 this law. If a given volume of hydrogen contains, say, 1000 molecules, the same volume of oxygen will contain the same number; and as the oxygen volume is 16 times as heavy as the hydrogen, it is clear that the weight of each molecule of oxygen will be 16 times that of each molecule of hydrogen. The molecules of hydrogen and oxygen each contain two atoms, hence, the atomic weights will also be in the proportion of 16 to I. In gases the spaces between the molecules are very-large in propor- tion to the size of the great molecules themselves. Elementary gases com- bine so as to produce a volume of gas which is equal to twice the volume that would be occupied by one atomic weight of hydrogen. The following instances are taken from among the commonest chemical compounds :— One volume of H and one volume of CI combine and produce two vol- umes of HCl. Two volumes of H and one volume of O combine and produce two vol- umes of H20. Three volumes of H and one volume of N combine and produce two volumes of NH3. If the substances were estimated, say in pints, then the resulting com- pounds would have.the volume of two pints. Some examples will make this plain =7— 47 cubic inches of H, weighing 1 grain, will combine with 47 cubic inches of CI, weighing 35.4 grains, and produce 94 cubic inches (z. e. 47 X 2) of hydrochloric acid (HCl), weighing 36.4 grains. The ratio of weights of equal bulks of hydrochloric acid and hydrogen is not 94 to 1, for the figure 94 is calculated for a molecule of HCl, while 1 represents an atom of H. We must compare molecule to molecule, that is HCl to HH, hence 94 to' 2 ;; 47 to I. By dividing 36.4 by 2 we get the weight of a quantity of hydrochloric acid equal to one atomic weight of hydrogen—viz. 18.2. This figure, 18.2, represents, therefore, the density or specific gravity com- pared to hydrogen. 94 cubic inches of H, weighing 2 grains, will combine with 47 cubic inches of O, weighing 16 grains, and produce 94 cubic inches of steam, H20, weighing 18 grains. If we divide 18 by 2, we get, as before, the density of steam compared to hydrogen—viz. 9. 47 cubic inches of N, weighing 14 grains, will combine with 141 cubic inches (47 X 3) °f H, weighing 3 grains, and form 94 cubic inches of ammonia, NH„ weighing 17 grains; and this weight, divided by 2, gives 8.5 as the density of ammonia compared to hydrogen. These principles are employed in determining the formulae of bodies. N and O combine to form a body called nitric oxide, which is sometimes 34 inorganic chemistry. written NO and sometimes N202. The following calculation will show which is correct:— The formula NO requires— One volume of N = 14 " " « O = 16 30 30-4-2=15. The formula N202 will require— Two volumes of N = 28 " " " O = 32 60 60 -e- 2 = 30. In the first instance the formula would indicate a vapor fifteen times as heavy as hydrogen; in the second case, thirty times as heavy. Experi- ment shows that the gas is actually fifteen times as heavy as hydrogen, and therefore justifies the formula NO. Since the introduction of a large number of atoms into a molecule does not increase the bulk occupied by a collection of such molecules, it is evident that the intermolecular spaces are much larger than the molecules themselves. The exact quantitative relations which exist in compounds, and the fact that symbols refer to definite proportions of the elements, enables us to employ the method of simple proportion to calculate the amounts involved in, or resulting from, any chemical combination. If it be required to know how much hydrogen is contained in 40 pounds of water, the formula ex- pressed in quantitative ratio is as follows:— H2 (2X0 = 2 O =16 H20 = 18 That is, 18 parts by weight of water contain 2 parts of hydrogen. Hence, 18 : 2 :: 40 : x; the fourth term will be the amount required. Percent- age composition is ascertained in this manner. The percentage of oxygen in water is obtained by the following proportion :— 18 : 16 :: 100 : x. The fourth term will be found to be 88.89, which is therefore the per- centage required. Any chemical formula or reaction may be converted in exact weight expressions. To determine, for instance, how much potassium volume combination. 35 iodide is required to exactly precipitate one gram of mercuric chloride, we must first express correctly the reaction, that is, the equation. This is as follows :— HgCl2 + 2KI = 2 KCl 4- Hgl2. The proportion by weights are:— Hg == 200 K = 39 Cl2 =71 I = 127 HgCl2 == 271 KI = 166 The proportion will be, as the molecular weight of the mercuric chloride is to that of the potassium iodide, with which it reacts, so is the given weight to that of the iodide required. Care must always be taken to use the mole- cular weights in the full proportion. In the present calculation, for instance, the molecular weight of the iodide must be doubled, because the chloride reacts with two molecules. Hence, HgCl2 2KI 271 : 332(166X2) :: 1 : x. Calculations of this character are of value to the student, who should practice them. Among other points of interest, they will serve to impress on the mind that formulae give only ratios by special factors, and do not con- vey directly the simple proportion. Thus, hydrogen iodide, HI, does not contain equal quantities of H and I, but only equal numbers of atoms. The calculation shows this :— H = 1 I = 127 HI= 128 Therefore, HI I 128 : 127 :: 100 : 99.2 percent, iodine; by which it is seen that hydrogen iodide contains less than one per cent. of hydrogen. DESCRIPTIVE CHEMISTRY. A complete table of the elements, their valencies, atomic weights and symbols, will be found at the end of the book. The following is a sum- mary of the important groups:— I. The Potassium Group includes hydrogen, lithium, sodium, potas- sium, rubidium, caesium and silver. They are positive monads, and have high affinity for members of the oxygen and chlorine groups. With oxygen they produce (except hydrogen and silver) powerful corrosive bases called the alkalies, and on this account are sometimes called the alkali metals. Hydrogen and silver are the only ones that occur free in nature. 2. The Chlorine Group includes fluorine, chlorine, bromine and iodine. They are negative monads, and are the only elements which form salts without the aid of some member of the oxygen group. For this reason they have been called the halogens, a word meaning " salt-formers." 3. The Oxygen Group includes oxygen, sulphur, selenium and tellu- rium. They are negative dyads, and possess the power of forming, with many elements, basic or acid compounds, according to the proportion in which they are combined. 4. The Nitrogen Group includes boron, nitrogen, phosphorus, arsenic, antimony, bismuth and gold. They are of uneven valency, triads or pentads; their electrical relations are intermediate in character, neither strongly posi- tive nor strongly negative. 5. The Carbon Group includes carbon, silicon, titanium, tin and some rarer elements. They are tetrads, and, like the nitrogen group, their rela- tions are intermediate. Boron is sometimes classed here, but it is best placed in the nitrogen group. Platinum may be included here. 6. The Calcium Group includes calcium, barium, strontium and lead. They are positive dyads, and form oxides which are slightly soluble in water, but much less caustic or corrosive than the alkalies proper, and are often called alkaline earths. Their sulphates, carbonates and phosphates are practically insoluble in water. 36 classification of elements. 37 7. The Zinc Group includes zinc, magnesium, cadmium and beryllium. They are never found free, but are tolerably easily reduced from their compounds. They are positive dyads, and each form a definite oxide which is insoluble in water, not caustic, but forming well marked salts. 8. The Iron Group is positive, and includes aluminum, iron, manga- nese, chromium, nickel, cobalt and probably several other elements the chemistry of which is not well known. They are not found in the metallic state, except in small quantity. Most of them form two sets of compounds, acting in one as dyads, in the other as double tetrads. Several form well- marked acid anhydrides. 9. The Copper Group includes copper and mercury, positive dyads, resembling each other in the power of forming two sets of compounds, in one of which they are in the unsaturated condition. In this condition they form chlorides insoluble in water, and are thus partly related to silver. 10. The Platinum Group.—A number of elements which are found in association with platinum are usually grouped together under the name of platinum metals. These are palladium, iridium, rhodium, ruthenium and osmium. Unclassified Elements.—Some of the elements are either so rare that their relations have not yet been satisfactorily studied, or their properties are such as to render it impossible to classify them satisfactorily under any system. 38 inorganic chemistry. Potassium Group.—The potassium group proper includes potassium, sodium, lithium, rubidium, caesium. They are positive monads, of high affinities. Their compounds are nearly all soluble in water. Their oxides and hydroxides are powerfully corrosive, and are known as the caustic alkalies. Hydrogen and silver, being positive monads, are also classed in this group, although they differ from the rest in some points. HYDROGEN. Hydrogen, H, i, exists in water and all organic substances. It is prepared by the action of electricity on water or dilute acids; also by the action of certain elements on water or acids. With acids the action generally occurs without the aid of heat; with water, sodium and potassium act in the cold; iron, magnesium, zinc, etc., require a high temperature. Na 4- H20 = NaHO 4- H. Mg4-H20 =MgO + Hr . Zn 4- H2S04 = ZnS04 + H2. The last method is generally used in the laboratory. Hydrogen is also evolved readily by the action of sodium hydroxide on aluminum. Al2 4- 6NaH0 = Na6 Al2 06 4- H6. Pure hydrogen is a colorless, tasteless and odorless gas. It is the lightest body known, a litre weighing 0.08961 grm. 100 cubic inches weigh 2.14 grains. It can be liquefied only by intense cold and pressure. It will burn in air or oxygen, forming water. Hydrogen, though not poisonous, will not sustain life; small quantities, when pure, can be inhaled without danger. Hydrogen is a positive monad, and a standard for valency, atomic and molecular weight and density. It combines with many elements. It is the essential element of acids. Water, H20.—When two volumes of hydrogen and one volume of oxygen are combined, complete condensation takes place and water is formed. Water exists abundantly, not only collected in masses, as in rivers, lakes and seas, but in combination with many substances and in a state of mixture with inorganic and organic bodies. Air almost always contains some water. Some living structures, as succulent fruits, jelly fish, etc., consist almost entirely of water. In natural conditions water is never pure. The matter HYDROGEN. 39 ordinarily dissolved varies from five to thirty grains to the gallon. When the quantity greatly exceeds this, and especially when peculiar substances, such as iron or sulphur, are present, it constitutes a mineral water. Sea water is very rich in mineral substances. The most important varieties of mineral waters are— Alkaline or carbonated waters, containing various carbonates in solution, generally with a quantity of free carbonic acid. Chalybeate waters, containing iron, generally as ferrous carbonate, with excess of carbonic acid. Sulphur waters, containing sulphureted hydrogen and other sulphides. Acid waters, containing some of the stronger acids. Saline or aperient waters, having large amounts of chlorides and sulphates. Water combines with many bodies. There are two principal classes of these compounds. In one the water seems to unite as such with the other substance, in the other class the molecule of water is broken up. Of the first kind of combination instances are seen in common crystals. The blue crystals sold as copper sulphate have the composition CuS04, 5H20. Water that is in this way part of a molecule, and essential to a crystalline form, is called water of crystallization. Substances that do not contain it in such a state of combination are said to be anhydrous. Water of crystallization is usually easily driven out by heat. The second form of the chemical action of water is seen if we mix water with quicklime; a violent action ensues, and the compound CaH202 results. A considerable number of oxides are capable of uniting thus with water and forming bodies known as hydroxides. The oxides which, by addition of water, produce hydroxides are called anhydrides. By subtracting H20 from any hydroxide we may reproduce the corresponding anhydride. Acids in this way furnish anhydrides:— Sulphuric acid. Sulphuric anhydride. H2S04 — H20 = S03. If the acid contains but one atom of hydrogen, we must, of course, double the formula before subtracting. Hence— Nitric acid. Nitric anhydride. 2HNO3 — H20 = N205. The term anhydride generally refers to those bodies which yield acids by addition of water. Those which yield hydroxides capable of neutral- izing acids are generally called bases. 40 INORGANIC CHEMISTRY. Hydrogen Dioxide, hydrogen peroxide, H202, H—O—O—H.—This body, sometimes called oxygenated water, is prepared by liberating oxygen in the presence of water, or when certain highly oxidized bodies are dis- solved, as in the following reaction :— Ba02 4- H2S04 = BaS04 4- H202. The presence of a considerable excess of water is necessary to the success of this reaction. (See Ozone.) It is acolorless, transparent, oily liquid, nearly one-half heavier than water; it is without odor, has a bitter taste, blisters the skin and bleaches organic colors. It is decomposed by heat and by many chemical substances, often explosively. The preparation of the concentra- ted liquid is difficult, but a somewhat dilute solution can be easily made and kept, and is now a commercial article, being used for bleaching hair, and as a disinfecting and oxidizing agent. POTASSIUM. Potassium, K, 39, occurs in many rocks and soils and in the ashes of land plants, also as nitrate and chloride. It is quite soft, quickly tarnishes in the air, and decomposes water rapidly, the escaping hydrogen being so highly heated as to take fire, burning with a purple flame, due to the presence of potassium. Specific gravity, 0.865. It is highly positive, and forms several oxides. Potassium Hydroxide, KHO, Caustic Potassa, is made by boiling potas- sium carbonate with slaked lime. CaH202 + K2COs = 2KHO 4- CaC03. Caustic potassa is a white, powerfully alkaline solid. Potassium Carbonate, K2C03, Salt of Tartar.—This is extracted from the ashes of land plants. Pure potassium carbonate is white, alkaline and moderately corrosive. Acid Potassium Carbonate, KHCOs, Salaralus, is a white crystalline body, and is used in effervescing mixtures, but acid sodium carbonate has of late years substituted it to a great extent. It is often called bicarbonate. Potassium Sulphate, K2S04, forms hard crystals, not very soluble in cold water. Acid Potassium Sulphate, KHS04, is sour and strongly acid to test paper. It is often called bisulphate. Potassium Nitrate, KN03, Nitre Saltpetre, is found on the surface of sodium. 41 the soil in India, and may be prepared artificially. Potassium nitrate is used in gunpowder and fireworks. Gunpowder consists of nitre, charcoal and sulphur. The gases produced at the moment of explosion are sufficient to occupy about 1200 times the bulk of the powder, and the effect is due to this sudden expansion. Potassium Chlorate, KC103.—The salt forms in flat, tabular crystals. It melts below a red heat, and at a little higher temperature gives off all its oxygen, leaving KCl. It is not very soluble in cold water, requiring about sixteen times its weight for solution. It is used largely as a source of oxygen and in medicine. Potassium Chloride, KCl, exists in sea-water and in some springs. It . resembles common salt. Potassium Bromide, KBr, forms cubical crystals, soluble in water. Potassium Iodide, KI, closely resembles the bromide. It is easily solu- ble in water. Potassium compounds are mostly soluble in water. A few, however, are so slightly soluble as to afford us serviceable tests. Platinum chloride produces with potassium salts, a yellow crystalline precipitate of potasso-platinum chloride, 2KCI, PtCl4. Tartaric acid gives a white crystalline precipitate of acid potassium tar- trate, KHC4H406. Potassium compounds give to flame a color which is a mixture of red and violet. SODIUM. Sodium, Na, 23.—Common salt, NaCl, is the most abundant compound. The ashes of sea plants contain sodium carbonate. Sodium closely resem- bles potassium, but is a little heavier and not so easily oxidized. The properties of its compounds are also much like those -of potassium. Sodium Hydroxide, NaHO, Caustic Soda, is very strongly alkaline and corrosive. It is prepared from sodium carbonate, in the same manner as potassium hydroxide. It is a powerful poison. The antidotes are the same as for potassium hydroxide. Sodium Carbonate, Na2C03, Sal Soda, forms large crystals, having the composition Na2C03, loH20, called sal soda or washing soda. On ex- posure to air these crystals effloresce, and fall to a white powder. Acid Sodium Carbonate, NaHC03, Baking Soda, is now much used in effervescing mixtures, such as the common baking powders, which are usually a mixture of cream of tartar and baking soda. Alum and acid 4 42 INORGANIC CHEMISTRY. calcium phosphate are often used as substitutes for the cream of tartar. The action of the powder is due to the sudden evolution of a large volume of carbon dioxide. NaHC03 + KHC4H406 = NaKC4H406 4- H20 4- C02. Sodium Sulphate, Glauber's Salt, Na2S04, ioH20, forms large crystals, which are remarkable for being more soluble in water at 930 F. (340 C.) than at any other temperature. Sodium Nitrate, NaN03, Chili Saltpetre, is used as a fertilizer, and also in the preparation of nitric acid. Sodium Chloride, NaCl, Common Salt, occurs in thick beds in various parts of the world, and is also prepared from sea water and certain brine springs, by evaporation. It dissolves in about the same amount in hot and cold water. Sodium Phosphates.—The most important form is disodium acid phos- phate, Na2HP04, which is used in medicine. Tri-sodium phosphate, Na3P04, is now made in large quantity as a cleansing, agent and for other purposes. Sodium Tetraborate, Na2B407. See Boric Acid. Sodium Silicate. See Silicic Acid. Sodium Thiosulphate, Na2S203, is much used in photography under the name hyposulphite. Its solution possesses the power of dissolving many of the salts of silver, which are insoluble in water. Sodium Sulphite, Na2S03, is used as a substitute for sulphurous acid in preventing fermentation, also as a reducing agent. Sodium compounds give a strong yellow color to flame, and are with very few exceptions quite soluble in water. Lithium, Li, 7.—Its principal sources are some rather rare minerals. Its salts resemble in the main those of potassium and sodium. Small amounts of lithium compounds are occasionally found in natural waters, constituting the so called lithia waters. Lithium imparts a crimson color to flame. Caesium, Cs, 133, and Rubidium, Rb, 85.4.—Their compounds are rare and resemble those of potassium. Caesium gives a blue color to flame • rubidium, a dark-red color. SILVER. 43 SILVER. Silver, Ag, 108.—Silver occurs native—that is, in the free state—in moderate abundance, also as sulphide, chloride and in other compounds. It is nearly always present in small amounts in lead ores. It is white and highly lustrous, easily worked into plates and wire, and the best conductor of heat and electricity known. Specific gravity, 10.5. It resists the action of oxygen and of caustic alkalies, but is attacked by sulphur and sulphides and by nitric acid. The sensitiveness of silver salts to light is the basis of photography. Silver melts at 16810 F. (9160 C). For use in the arts it is usually alloyed with copper. The standard alloy of the English mint (sterling silver) contains Txj copper; that of the United States Mint (coin silver) ^ copper. Silver Oxide, Ag20.— Oxygen is absorbed by melted silver, but no com- bination is formed. When a solution of a silver salt is treated with potassium hydroxide, and the precipitate gently heated, silver oxide is formed. Silver Nitrate, AgN03, Lunar Caustic, is easily made by dissolving the metal in nitric acid. Silver nitrate forms colorless crystals, very soluble in water, and, when mixed with organic matter, blackened by light. It fuses at 4260 F. (2190 C), and is often cast in sticks for use as a caustic. The property of form- ing a black, difficultly soluble precipitate with organic matter is utilized in the manufacture of hair-dyes and marking-ink. Silver Chloride, AgCl, is found as a mineral, and is easily formed arti- ficially by adding any soluble chloride to silver nitrate. NaCl 4- AgN03 = AgCl 4- NaN03. It forms a heavy white precipitate like curdled milk, turning violet in the light, especially if organic matter be present. Silver is easily reduced from most of its compounds by heat alone, and by reducing agents. 44 INORGANIC CHEMISTRY. Chlorine Group.—This includes chlorine, bromine, iodide and fluorine, negative monads of high affinity. Chlorine generally expels bromine from combination, and bromine expels iodine. CHLORINE. Chlorine, CI, 35.46.—The most abundant compound is common salt, NaCl. Many other chlorides are found as minerals. Several methods for the preparation of chlorine have been devised; nearly all of them depend upon the oxidation of some chloride. [a) By heating a mixture of manganese dioxide and hydrochloric acid, Mn02 + 4HCI = MnCl2 4- 2H20 + Cl2. (b) By heating a mixture of common salt, sulphuric acid and manganese dioxide, Mn02 4- 2NaCl 4- 2H2S04 = MnS04 4- Na2S04 4- 2H20 4- Cl2. [c) By the action of hydrochloric acid upon potassium chlorate, potas- sium bichromate or bleaching-powder. These methods yield an impure chlorine, and are suitable for the preparation of small amounts. The reaction with potassium chlorate may be represented as follows :— 2KC103 4- 4HCI = 2KCI 4- C1204 4- Cl2. Chlorine is a greenish-yellow, highly irritating gas. It can be condensed to a greenish liquid. The gas is about two and a half times as heavy as air; one litre weighs 3.1808 grms.; water dissolves about three volumes, acquiring the color and odor of the gas; the solution, known as chlorine water, does not keep well. The affinities of chlorine are very great. It combines directly with most of the metals, decomposes water, and changes many organic substances. Its affinity for hydrogen is increased by light. It has many applications as a bleaching and disinfecting agent, but is rarely used in the form of gas, the effects being generally obtained by the use of bleaching powder (see Hypochlorites). Chlorine is a monad in its strictly negative relations, i. e., in simple chlor- ides, but in association with the powerful negative, oxygen, it seems to assume higher valencies. It is also capable of replacing hydrogen, atom for atom, giving rise to an important and extensive series of substitution compounds, which are considered in connection with organic chemistry. CHLORINE. 45 Hydrochloric Acid, HCl, Muriatic Acid, Spirit of Salt.—This acid may be formed by the direct union of its elements, but the practical process is the. action of common salt and sulphuric acid, according to the following reaction :— 2NaCl 4- H2S04 = Na2S04 4- 2HCI. This reaction requires a high temperature. In ordinary experiments and on the small scale the reaction is NaCl 4- H2S04 = NaHS04 4- HCl. Hydrochloric acid is a colorless gas of a strong pungent odor and poisonous to animals and plants. Its density is 18.181; a litre weighs 1.63 grms. It does not burn nor support ordinary combustion, but some substances burn in it, forming chlorides. Water will absorb nearly 500 volumes, producing a strongly acid solution, which is the common hydro- chloric or muriatic acid. When pure this is a colorless, fuming, strongly acid liquid. Many metals dissolve in hydrochloric acid, forming chlorides and liber- ating hydrogen; oxides dissolve, forming chlorides and water; sulphides, form hydrogen sulphide, etc. The following reactions illustrate this :— Zn 4- 2HCI = ZnCl2 4- H2. ZnO 4- 2HCl = ZnCl2 4- H20. FeS 4- 2HCI = FeCl2 4- H2S. With many oxides, some chlorine escapes, as shown in the reaction with manganese dioxide or lead dioxide. We may assume such reactions to occur in two stages, thus :— Pb02 4- 2HCI = PbCl2 + H20 4- O. The nascent O oxidizes a further quantity of acid, 2HCI 4- O = H20 4- CI,. A mixture of about three parts nitric with five parts hydrochloric acid has been long used under the names aqua regia and nitro-muriatic acid. It dissolves gold and platinum, and owes its efficacy in part to the free chlorine which is formed by the oxidizing action of the nitric acid upon the hydrochloric acid. Compounds of Chlorine and Oxygen.—Several of these are known in 46 INORGANIC CHEMISTRY. the free state. Others are known only in combination, as in the following series:— HCIO . . . Hypochlorous acid. H—O—CI. in HCIO, . . . Chlorous " H—O—C102. HCIO, . . . Chloric " H—O—C102. 6 VII HC104 . . . Perchloric " H—O—C103. Any positive may take the place of the hydrogen. Chloric Acid, HC103.—When chlorine acts upon metallic oxides or hydroxides at a temperature of over 6o° F. (I5.5°C.) chlorates will be pro- . duced, according to the following reaction:— 6KH0 4- Cl6 = KC103 + 5KCl 4- 3H20. The chlorates are useful for the large amount of oxygen which they contain, and which they yield easily when heated. Potassium chlorate is the substance from which oxygen is usually prepared. Perchloric acid is obtained by heating dilute chloric acid. The perchlorates resemble the chlorates. When chlorine acts upon hydroxides at a low temperature, especially calcium hydroxide, hypochlorites are produced. (See calcium hypo- chlorite.) A weak solution of hypochlorous acid is sometimes used for removing ink. Chlorine combines with nitrogen to form a body called nitrogen chloride, NC13. It is an oily liquid, which decomposes very easily and with violent explosion. BROMINE. Bromine, Br, 8o.—Bromides occur in sea water, sea plants, brine springs and in a few minerals. Bromine may be prepared by processes analogous to those of chlorine—acting upon bromides by means of oxidizing agents, such as a mixture of sulphuric acid and manganese dioxide; 2KBr 4- Mn02 + 2H2S04 = K2S04 4- MnS04 4- 2H20 4- Br2. It may also be directly expelled by the superior affinity of chlorine • KBr 4- CI = KCl 4-Br. Bromine is a dark red liquid, which at ordinary temperatures evolves irritating red vapors. This liquid is three times as heavy as water and IODINE. 47 boils at 1450 F. (630 C.) and freezes at —120 F. (—25° C). It is soluble in water, and is often conveniently used in that form. Its chemical pro- perties are similar to those of chlorine, but not so energetic. It bleaches vegetable colors and decomposes many organic bodies. It combines energetically, forming bromides, of which those of hydrogen, potassium and ammonium are the most important. It also forms oxygen compounds analogous to those of chlorine. Hydrogen Bromide, Hydrobromic Acid, HBr.—This substance cannot be conveniently prepared by the action of sulphuric acid upon a bromide, but is obtained by using a mixture of phosphorus, powdered glass and bromine, or by the action of phosphoric acid upon a bromide. It resembles hydrochloric acid in its properties, and is used in medicine. Salts of Bromic Acid, HBr03, and Hypobromous Acid, HBrO, are also known. They closely resemble the corresponding chlorine compounds. IODINE. Iodine, I, 127.—Iodides occur in association with bromides and chlorides in sea water and sea plants. Iodine is prepared from any iodide, by processes similar to those for bro- mine, either by the action of chlorine or of a mixture of manganese dioxide and sulphuric acid. The reactions are, KI 4- CI = KCl 4- I, or, 2KI 4- Mn02 4- 2H2S04 = K2S04 4- MnS04 4- 2H20 4- I2. It forms bluish-black crystalline masses with metallic lustre. It evapo- rates slowly at ordinary temperatures, melts at 2250 F. (1070 C), and boils at 3470 F. (1750 C). The vapor has a deep violet color and a peculiar odor, somewhat like that of chlorine, but is not so irritating. The solid dissolves in alcohol, ether and carbon disulphide; also in water containing potassium iodide (Lugol's solution), only slightly in pure water. It has some bleaching, oxidizing and disinfecting powers. One of its important proper- ties is that of producing a blue color with starch. For this action the iodine must be in the free state; the iodides give no color. The chemical relations of iodine are substantially the same as those of chlorine and bromine. Hydriodic Acid, HI, Hydrogen Iodide.—This is prepared by methods 48 INORGANIC CHEMISTRY. similar to those used for hydrogen bromide, which body it closely resem- bles. It is used in medicine. By the action of strong ammonia upon powdered iodine a brownish sub- stance is produced, having the composition NHI2. It is easily handled while wet, but when perfectly dry it explodes, with a loud report, on the slightest touch. FLUORINE. Fluorine, F, 19.—This is tolerably abundant in fluor spar, CaF2, and cryolite, 6NaF,Al2F6, and some rarer minerals. It exists in the stems of grasses and in bones and teeth. Fluorine is a gas, the properties of which have not been thoroughly studied, on account of the difficulty of obtaining it. It combines with every known element except oxygen. It is remarkable for its affinity for silicon. Hydrogen Fluoride, Hydrofluoric Acid, HF.—This body is prepared by acting on calcium fluoride, CaF2, with sulphuric acid. The pure HF is a gas, but will dissolve in water. It acts powerfully, especially on siliceous materials. It is used for etching designs on glass. Strong solution of hydrogen fluoride is now sold in gutta-percha bottles, upon which it has no action. OXYGEN. 49 Oxygen Group.—This includes oxygen, sulphur, selenium and tellu- rium, negative dyads. OXYGEN. Oxygen, O, 16.—This exists in water, air, all animal and vegetable tissues and in the great majority of minerals. It constitutes over half the matter composing the earth. The oxide of mercury, silver and of some other elements are decomposed by heating. The decomposition of mercuric oxide in this manner was the means of the discovery of the gas, the reaction being : HgO = Hg + O. Chlorates and nitrates are decomposed by heat, giving off large quantities of oxygen, but not always quite pure. Potassium chlorate mixed with about one-quarter of its weight of manganese dioxide is preferred. The reaction concerns the potassium chlorate only, which is simply decomposed— KC103 = KCl 4- 03. The exact manner in which manganese dioxide acts has not been explained. Oxygen is colorless, odorless and tasteless; it is one-tenth heavier than air, one litre weighing 1.43 grm. It is continually being absorbed by living animals in the process of respiration, to which function it is essential, and is also consumed in ordinary combustion. All bodies which burn in air burn with increased brilliancy and rapidity in pure oxygen. Plants under the influence of light both excrete and absorb oxygen. Oxygen combines with every other element except fluorine, and with many in several proportions. The chemical functions of these oxides are dependent in part upon the number of oxygen atoms present. Those of manganese may be taken as examples :— MnO, .... Powerful base. Mn203, . . . Weak base. Mn02, . . . Indifferent. Mn03, . . . Forming an acid (anhydride). These illustrate the law that small proportions of oxygen tend to produce bases, high proportions anhydrides or acid-forming oxides, and interme- diate proportions bodies of uncertain or indifferent character. Elements of intermediate electrical character are incapable of forming basic oxides. Thus, nitrogen forms five oxides, but none of them has basic powers, but several form powerful acids. 50 INORGANIC CHEMISTRY. Oxygen is slightly soluble in water, and upon this fact depends the exist- ence of most forms of aquatic life. The removal of oxygen from any compound is called reduction; the addition of oxygen is called oxidation. Substances which bring about the former action are called reducing agents, those causing the latter effect, oxidizing agents. The terms are now extended to actions involving the removal or addition of other negative elements. Thus the conversion of ferric chloride into ferrous is called a reduction. Ozone.—Ozone is a modified form of oxygen in which three atoms con- stitute a molecule. The contrast between the conditions is shown thus:— Ordinary Oxygen 0 = 0 Ozone may be prepared by passing electrical sparks through air or oxy- gen, by the slow oxidation of phosphorus or of turpentine, or other essen- tial oils, by the decomposition of water by the galvanic current, by the action of acids upon certain bodies rich in oxygen. By all these methods only a small proportion of the oxygen is converted into ozone. Thus, when barium dioxide or potassium permanganate is mixed with strong sul- phuric, some ozone forms; 3Ba02 4- 3H2S04 = 3BaS04 + O,. Ozone is heavier than oxygen, and soluble in water. When the properties of an element are modified without alteration of composition, the change is said to be allotropic. Ozone is an allotropic form of oxygen. SULPHUR. Sulphur, S, 32, occurs native—i. e.,'\w the free state; also in combina- tion, forming sulphides and sulphates, and in some animal and vegetable structures. It is seen in several forms; roll sulphur or brimstone, made by casting the melted sulphur in moulds ,v flowers of sulphur, made by condens- ing the distilled sulphur in a cool chamber, and precipitated sulphur, a finely-divided medicinal form, prepared by precipitation. Ordinarily, sulphur is a brittle, yellow solid, insoluble in water, highly combustible, fusible at about 2500 F. (1210 C.) and boiling at 8360 F. Ozone. o / \ 0 — 0 SULPHUR. 51 (4470 C). It is a non-conductor of electricity, and becomes highly elec- trical by friction. It assumes several allotropic forms, among which is a somewhat plastic mass, made by rapidly cooling melted sulphur. This form is not permanent, but soon changes to the ordinary form. Like oxygen, it combines directly, when heated, with many metals. In these compounds the sulphur is negative, and usually dyad. With the mem- bers of its own group it combines in several proportions, showing valencies of two, four and six, and perhaps even higher. In combination with oxygen and chlorine it is regarded as positive to them. In general its compounds are analogous in composition to those of oxygen, and since many oxides act as bases toward the ordinary acids, so the corresponding sulphides act as bases toward what are called the sulphur acids. Thus we have— K20 + C02 = K2COs.....• Potassium carbonate K2S + CS2 = K2CS3...... " sulphocarbonate. In such compounds the sulphur is substituted for the oxygen, atom for atom, and the name is formed by prefixing either the syllable " sulph " or " thio " to the name of the acid. Sulphur is used in the arts for vulcanizing caoutchouc and in the manu- facture of gunpowder. Match-sticks are tipped with it to make the friction composition ignite the wood more surely. Sulphur forms two compounds with hydrogen :— H2S......Hydrogen sulphide or sulphureted hydrogen. H2S2......Hydrogen disulphide. Hydrogen Sulphide, H2S.—This substance is a gas. It exists in solution in some spring waters, also in the emanations from decomposing animal and vegetable matters. It may be made by acting upon sulphides with strong acids. Ferrous sulphide and sulphuric acid are used :— FeS 4- H2S04 = FeS04 4- H2S. Hydrogen sulphide may also be obtained by heating a mixture of hydro- chloric acid and antimony sulphide. Sb2S3 + 6HC1 = 2SbClg 4- 3H2S. Hydrogen sulphide is a colorless gas, of disagreeable odor, and is easily combustible. Water at ordinary temperature dissolves about three volumes, acquiring the odor and chemical properties of the gas. The important property of hydrogen sulphide is its power of precipitating many elements as sulphides. These precipitates being generally distinct in color and 52 INORGANIC CHEMISTRY. highly insoluble, their production is not only a test for the presence of such bodies, butalsoa means of separating them from solution. Hydrogen Disulphide, HS, H-S-S-H.—This substance is a yellow oily liquid, of a disagreeable odor, decomposing easily, and is analogous to hydrogen dioxide. Compounds of Sulphur with Oxygen.—Sulphur forms with oxygen a number of acid-forming oxides or anhydrides, some of which are known only in the hydrated condition—that is, as acids. The important ones are:— Anhydride. Acid. Name. SO........H2S02......Hyposulphurous. S02........H2S03......Sulphurous. S03........H2S04......Sulphuric. H2S203......Thiosulphuric. The commercial hyposulphites are salts of thiosulphuric acid, properly called thiosulphates. Sulphur Dioxide, Sulphurous Anhydride, S02.—This substance is the usual product of the burning of sulphur or the sulphides in air or in oxygen. It may also be obtained by deoxidizing sulphuric acid with copper, mer- cury, charcoal, silver or sulphur. The reaction in the preparation of it by the action of sulphuric acid on copper is— Cu 4- 2H2S04 = CuS04 + 2H20 + S02. Mercury and silver also give similar effects. Carbon and sulphur act as follows :— C 4- 2H2S04 = 2S02 4- 2H20 4- C02. S + 2H2S04 = 3S02 + 2H20. Sulphur dioxide can also be obtained by the action of ordinary acids, e.g., sulphuric, on sulphites. Sulphur dioxide is a colorless gas, of the well-known odor of burning matches. It can easily be condensed to a colorless liquid by a mixture of snow and salt. The liquid is sulphur dioxide, S02, and not sulphurous acid. Sulphur dioxide in water forms sulphurous acid, H20 4- SO = IV H2S03 (HS02HO) which remains in solution, giving the liquid all the common properties of an acid. The solution is also a powerful reducing agent, and has moderate bleaching power. It slowly becomes converted into sulphuric acid when exposed to air. SULPHUR. 53 The anhydride, free acid and its salts are antiseptic agents—that is, pre- vent putrefaction and fermentation. They act by killing the minute organ- isms, which are the causes of such changes. The salts of sulphurous acid are called sulphites; monads form two com- pounds, acid and normal. Thus, potassium gives us— Acid Potassium Sulphite. Potassium Sulphite. KHS03. K2S03. Dyads give one sulphite. From calcium we have but CaS03. Sulphur Trioxide, Sulphuric Anhydride, S03, is a soft, white, odorless solid, in long, silky crystals like asbestos. Exposed to the air, it absorbs water rapidly and becomes converted into sulphuric acid. VI • Sulphuric Acid, H2S04 (H0)2S02, oil of vitriol, occurs in waters of volcanic and mining districts, and in the air of towns, in the latter case derived from the oxidation of sulphurous acid. The compounds of sulphuric acid (sulphates) are of frequent occurrence. Calcium and barium sulphates are abundant minerals; sodium sulphate occurs in many natural waters. The original method of preparation was the distillation of the sulphates, especially the ferrous sulphate, FeS04. The acid so formed is more concen- trated than the ordinary commercial article. This latter is made as follows: Vapors of nitric and sulphurous acids are mixed with steam and air in a large leaden room, the floor of which is slightly inclined and covered by a few inches of water. The sulphurous acid is derived either from the burning of raw sulphur or the roasting of pyrites; the nitric acid, from the action of sodium nitrate on sulphuric acid. The chemical changes are somewhat complicated, and are not wholly understood. Pure sulphuric acid is a colorless, oily liquid, of a specific gravity of 1.848, boiling at about 6400 F. (3380 C). It is highly corrosive and poisonous. The antidotes are mild alkaline substances, such as baking soda, magnesia, chalk and soap. Exposed to the air, it absorbs water in considerable amount. When added to water it produces heat, and the dilution of any considerable quantity must be performed by slowly pouring the acid into the water with constant stirring. Sulphuric acid will decompose many organic substances, extracting the hydrogen and oxygen in the proportion to form water, and leaving the carbon. Commercial sulphuric acid is usually more or less brown, or even black, from the carbon set free from particles of dust, straw, etc., which accidentally fall into it. It always contains a small quantity of water—about one molecule to twelve of acid:— H20 4- I2H2S04. 54 INORGANIC CHEMISTRY. Its properties, boiling point, etc., are practically the same as those of the pure acid. Nordhausen or Fuming Sulphuric Acid, the original oil of vitriol, is obtained by the distillation of green vitriol. It corresponds to the formula H2S207, being two molecules of sulphuric acid minus one of water, 2H2S04 — H20 = H2S207. Acids derived in this way are known as di-acids or pyro-acids. The graphic formulae are as follows:— Sulphuric Acid. Di-Sulphuric Acid. (2 molecules.) HO- HO—SO, l1o~S°2 - H20 = A H°—so I H0- * HO-S02 It is denser and even more corrosive than the common acid, and unites with water with great energy. It is used for dissolving indigo and for a few other purposes. When heated, sulphur trioxide distils off, and the ordinary acid is left. The properties of sulphuric acid are greatly modified by dilution; its corrosive and charring action may be entirely removed by adding much water. The salts of sulphuric acid are called sulphates. Monads give, of course, two sulphates, acid and normal. Sodium gives us— Acid Sodium Sulphate. Sodium Sulphate. NaHS04 Na2S04 Dyads give one sulphate. From barium we get only BaS04 barium sulphate. Most sulphates, except those of the calcium group, are freely soluble in water. The commercial sulphuric acid contains several impurities, of which the most important are arsenic and lead. Thiosulphuric acid, H2S203, commonly but erroneously called hyposul- phurous acid, has not been obtained in the free state. Sodium thiosulphate is much used in photography. These compounds may be regarded as sulphuric acid in which one atom of oxygen is replaced by sulphur; hence thiosulphuric, not thiosulphurous, acid. Its graphic formula may be given VI thus: HS—S02—OH. The thiosulphates are powerful reducing agents. Sulphur forms several compounds with chlorine: S2C12, sulphur chlo- ride; SC12, sulphur dichloride; SC14, sulphur tetrachloride. SELENIUM—TELLURIUM—CALCIUM. 55 Selenium, Se, 79.5, is found native and also as selenides. It is rare. The physical properties of selenium resemble those of sulphur. It shows several allotropic forms. The compounds of selenium are analogous to those of sulphur; we have H2Se.......Hydrogen selenide. Se02.......Selenium dioxide. H2SeOs......Selenous acid. H2Se04......Selenic " Tellurium, Te, 128, is found native, and also in union with bismuth, gold, etc. It is rare. It has a metallic lustre and pinkish color, fuses just below a red heat, and boils at a somewhat higher temperature. Calcium Group.—This includes calcium, barium, strontium and lead. They are positive dyads, and form oxides slightly soluble in water; those of the first three were formerly called the alkaline earths. The sulphates are insoluble or sparingly soluble in water. CALCIUM. Calcium, Ca, 40, occurs mainly in the form of sulphate, carbonate, phosphate and fluoride. It is light yellow and malleable; it oxidizes easily. Calcium Oxide, Quicklime, CaO, obtained by heating the carbonate to • redness (CaC03 = CaO -f- C02), is a white, infusible solid, which neu- tralizes the most powerful acids and combines with water with great energy, forming Calcium Hydroxide, Slaked Lime, CaH202, a soft, white, caustic pow- der, slightly soluble in cold water (about 9 grains to the pint). The solu- tion is known as lime-water; a thick mixture of calcium hydroxide with water is known as milk of lime. Calcium Carbonate, CaC03.—In a non-crystalline condition this is seen as chalk, marble and limestone; in crystals it forms Iceland spar and arra- 56 INORGANIC CHEMISTRY. gonite. It is the chief constituent of shells. It may be prepared by adding sodium carbonate to calcium chloride:— CaCl2 + Na2C03 = CaC03 + 2NaCl, or by passing carbon dioxide through calcium hydroxide solution. It is a white solid, almost insoluble in pure water. It dissolves more freely in water containing carbon dioxide, for which reason many natural waters contain it. When present in an amount more than a few grains to the gallon, a hard water is formed, which has the property of curdling soap and preventing the formation of a lather, due to precipitation of insoluble calcium salts, formed from the soap. Boiling will precipitate the calcium carbonate and soften the water. The excess of carbon dioxide will also be lost by exposure to air, and calcium carbonate will then be deposited. Such an action occurs in caves, forming stalactities and stalagmites. Calcium Sulphate, CaS04, usually occurs crystallized with 2H20, con- stituting selenite, gypsum and alabaster, sometimes, however, anhydrous. It is soluble in about 400 times its weight of cold water. It is a frequent ingredient of natural water, causing the same effect of hardness mentioned above; but as it does not owe its solubility to carbon dioxide, boiling does not soften the water, and hence the condition is called permanent hard- ness. When the crystallized mineral is heated moderately.it loses water and become a soft white powder, plaster-of-Paris, which when mixed again with water reabsorbs it and becomes a hard mass, expanding slightly in bulk, and thus suited for taking casts of any object. Calcium Phosphate, Ca3(P04)2, occurs in bone and in modified form in some mineral deposits. Its chief use is in fertilizers and in the manufacture of phosphorus and its compounds. It is insoluble in water, but soluble in dilute acids. Calcium Hypophosphite, Ca(PH202)„, is used in medicine. Calcium Chloride, CaCl2, is obtained by acting on the carbonate with hydrochloric acid:— CaC03 4- 2HCI = CaCl2 4- H20 4- C02. It is very soluble in water. The anhydrous salt has a powerful affinity for water, and is used for drying gases. Calcium Hypochlorite, Bleaching Powder.—This is produced by passing chlorine into slaked lime, keeping the mixture cool. The exact composition of the commercial bleaching powder is undeter- BARIUM. 57 mined; it contains some unchanged calcium hydroxide, and exhibits the reactions of a mixture having the formula Ca(C10)2 + CaCl2, but is considered by some to be more accurately expressed by the formula CI / Ca \ O—CI. Bleaching powder, when in good condition, is a loose, dry, white powder, with a faint and not disagreeable odor. If it smells of chlorine it is in bad condition. It dissolves in water. The solution possesses strong bleaching and disinfecting powers, for which purposes it is largely used. Acids, even carbonic acid, decompose it, setting chlorine free. The commercial salt is Qften erroneously called chloride of lime. Calcium Fluoride, CaF2, is found as the mineral, Fluor Spar. Small quantities exist in bones and teeth. Calcium compounds give to flame a reddish color. BARIUM. Barium, Ba, 137, occurs as sulphate and carbonate. It is a moderately heavy, pale yellow, easily oxidized solid. Barium Oxide, Baryta, BaO, easily takes up water, forming barium hydroxide, BaH202, which is soluble in water. Barium Dioxide, Ba02, is used in making hydrogen dioxide. Barium Carbonate, BaC03, is found in nature as witherite. It is insoluble in pure water. Barium Sulphate, BaS04, Baryles, is found abundantly as the gangue or rock surrounding metallic veins. It is very heavy, white, and often finely crystallized. It is used as a substitute and adulterant for white lead, and may be used as a source of the other barium salts. Barium Nitrate, Ba(N03)2, is used in making green fire. Barium Chloride, BaCl2, is used as a test solution for sulphates. Barium communicates to flame a yellowish-green color. Sulphuric acid produces in barium solutions a white precipitate of barium sulphate, insoluble in water and acids. 5 58 INORGANIC CHEMISTRY. Strontium, Sr, 87.5, resembles barium in its compounds and chemical relations. It occurs as sulphate and carbonate. Strontium Nitrate is used in making red fire. Strontium compounds give to flame a crimson tint. Its solutions produce with sulphuric acid a white precipitate resembling that given by barium. LEAD. Lead, Pb, 207, occurs as sulphide [galena), carbonate, sulphate and phosphate. Lead is a soft metal, but resists the action of air and of some strong acids, for which reason it is used in chemical apparatus. Pure water, free from air, has little action on lead, but aerated water oxidizes and dissolves it in small quantity. Phosphates, carbonates and silicates interfere with this action, because they precipitate insoluble lead compounds. Lead melts at 6170 F. (3250 C). Specific gravity, 11.5. Some important alloys of lead are : type-metal, containing 4 parts lead and 1 part antimony; solder, about equal parts of lead and tin; pewter, I part lead and 4 parts tin. Lead Monoxide, PbO, Litharge, Massicot, is a yellowish or reddish powder, slightly soluble in water and neutralizing the most powerful acids. It fuses at a red heat, and in this condition combines easily with silica, for which reason it is often used in glazing earthenware, but such glaze is easily attacked by acids and may give rise to lead poisoning. Lead Dioxide, Pb02, Puce, is a brown powder, insoluble in water. It is the anhydride of plumbic acid H4Pb04. Red Lead, Minium, usually Pb304.—It forms a bright red powder, not constant in composition. It may be regarded as Pb2Pb04, being the lead salt of plumbic acid. Lead Sulphide, PbS, is abundant as a mineral, galena, forming large, cubical, lead-colored crystals. It can be formed by adding hydrogen sul- phide to lead solutions. Lead Carbonate, PbC03, White Lead, occurs as a mineral, but is made artificially on a very large scale for use in paints. The white lead of com- merce is an hydroxy-salt of varying composition, approximately 2PbC03 4- PbH202, which will dissolve in water containing carbonic acid. Lead Sulphate, PbS04, is a white insoluble powder, produced by adding sulphates to lead solutions. copper. 59 Lead Chloride, PbCl2, forms slender crystals, not very soluble in cold water. Lead Iodide, Pbl2, forms a bright yellow powder sparingly soluble in cold water. Lead Chromate, PbCr04, Chrome Yellow, is described under chromium. Copper Group.—This includes copper and mercury. They are positive dyads, but also form a series of unsaturated compounds. COPPER. Copper, Cu, 63.5, occurs native in large masses, also as sulphide (copper pyrites), and as oxide, silicate and carbonate. In small amounts it is widely distributed in nature, occurring in many articles of food, and generally in the human body, especially in the liver and brain. Copper is distinguished by its red color. It is heavy, specific gravity, 8.9; hard, and can be worked into thin plates or wire; melts at 19960 F. (1901° C). It conducts heat and electricity very well, and resists the action of the air, but is slightly oxidized and dissolved by acids when in contact with air. Salt water and the acids of fruits will produce this effect, and hence the danger of using copper vessels for kitchen purposes. Copper furnishes some valuable alloys—brass, gun-metal, etc. It forms two sets of salts; in the cupric series, the metal is dyad and saturated; in the other, cuprous, the copper is unsaturated. The cuprous salts are mostly colorless and tend to absorb oxygen or other negatives, becoming saturated (cupric) compounds; the cupric salts are green or blue. Copper Monoxide, CuO, Cupric Oxide, Black Oxide, is a heavy, black powder. Copper hydroxide, CuH2Oa, formed when copper salts are mixed with an alkali, is a bluish green mass, dissolving in ammonia, producing a clear, deep-blue liquid; but with potassa and soda no solution occurs except in the presence of certain organic bodies, especially sugar, when a clear blue solution is also formed. If such solution is boiled, the cupric hydrate is changed to cuprous, which is precipitated as a red or orange powder. Copper Carbonate, CuC03, appears not to be known in the pure state. Various oxycarbonates, malachite and azurite, exist as minerals, and similar compounds are obtained by the addition of carbonates to copper salts. 60 INORGANIC CHEMISTRY. Copper Sulphate, CuS04, Blue Vitriol, Blue Stone, forms large blue crystals soluble in water, and having the composition CuS04, 5H20. Copper Chloride, CuCl2, is in green crystals, soluble in water. Copper Arsenile, CuHAs03, Scheele's or Paris Green, is a bright green powder. It is used for killing potato-bugs and also as a color. It is a violent poison. A compound containing copper acetate and arsenite is known as Schweinfurth green. Cuprous Salts.—Cuprous Oxide, Cu20, is the result of the reducing action of sugar on a mixture of caustic alkali and cupric hydrate. Cuprous Chloride, CuCl, is a white solid, insoluble in water. The cuprous salts are easily converted into cupric. Copper |gives a green tint to flame. Potassium ferrocyanide gives a mahogany brown precipitate of copper ferrocyanide. A clean piece of iron immersed in a solution of copper becomes quickly covered with a bright red coating of copper. This is an easy method for detecting it in pickles, green peas, etc., which are often colored by copper. MERCURY. Mercury, Hg, 200.—This metal is found native, and as sulphide (cin- nabar). It is liquid at the ordinary temperature, freezing at —400 F. and C, and boiling at 6750 F. (3570 C.); when pure it does not tarnish in dry or moist air, but above 3000 C. it absorbs oxygen. It is very lustrous and heavy; specific gravity, 13.56. Combinations of mercury with other metals are known as amalgams. These are either soft or hard, according to the quantity of mercury used. Two series of salts are known, cor- responding to the copper salts, and called respectively mercurous and mercuric salts. Mercuric Oxide, HgO, Red Precipitate, is a red or yellowish-red pow- der. It is an active base. Mercuric Sulphate, HgS04, is a white powder, which is decomposed by water, forming a yellow oxysulphate, HgS04 4- 2HgO, called turpeth mineral. Mercuric Nitrate Hg(N03)2, is generally seen in solution with excess of nitric acid, forming the acid mercury nitrate used in medicine. Mercuric Chloride, HgCl2, Corrosive Sublimate, is a heavy, white, crys- talline powder, soluble in water and ether, and having an acrid, metallic taste. It is extremely poisonous, about five grains being a fatal dose. It • ZINC. 61 forms with albumin an insoluble precipitate. Dilute solutions of mercuric chloride are now much used as an antiseptic in surgery. Mercuric Iodide, HgT2, Red Iodide, is formed when corrosive sublimate is mixed with potassium iodide :— HgCl2 + 2KI = Hgl2 4- 2KCI. It is at first yellow, but changes to a brilliant scarlet. Mercuric Sulphide, HgS, Vermilion, Cinnabar, is an important ore of mercury. The Mercurous Salts are mostly of little importance. Mercurous Oxide, Hg20, is a black powder, easily decomposed. Mercurous Chloride, HgCl, Calomel, is a white, heavy, tasteless powder, insoluble in water. Mercuric salts give with potassium iodide a yellow precipitate of Hgl2, changing to scarlet and soluble in excess of the precipitant. Any compound containing mercury will give with Reinsch's test [q. v.) a bright silvery coating on copper foil, easily driven off by heat. Zinc Group.—This includes zinc, magnesium and cadmium. They each form but one definite oxide, which is insoluble in water, not caustic, capable of forming well-marked salts. Beryllium, a rare element, is also included in this group. ZINC. Zinc, Zn, 65.5, exists as sulphide [blende), carbonate [calamine), sili- cate [electric calamine) and as oxide. It is hard, bluish-white, generally decidedly crystalline. Sp. gr. 7.14. It melts at 7700 F. (4100 C), and distils at about a red heat. It is brittle at ordinary temperatures. When highly heated it bums with a greenish-white flame, producing ZnO. Acids and strong alkalies dissolve it. It is employed in making several important alloys, as brass and gun-metal, which contain copper and zinc, and German silver, which contains copper, zinc and nickel. Galvanized iron is simply iron covered with a layer of zinc by dipping it in a bath of melted zinc. Commercial zinc is very likely to contain arsenic. Zinc Oxide, ZnO, Zinc White, is a soft powder, yellow when hot, white 62 INORGANIC CHEMISTRY. when cold. It is used as a paint, as an application in surgical dressings and as a face powder. Zinc Hydroxide, ZnH202, is a white body, soluble in acids and alkalies. Zinc Sulphate, ZnS04, White Vitriol, forms white crystals having the formula ZnS04, 7H20. They are soluble in water, and act as an emetic. Zinc Chloride, ZnCl2, forms white masses, which absorb water rapidly from the air [deliquesce) and make a strong solution. Zinc chloride is a powerful corrosive, coagulates albuminous matter, and is used as a pre- servative in anatomical preparations, also as an application in dentistry. When a strong solution of zinc chloride is mixed with zinc oxide, the two combine and form a hard, white, insoluble mass which is used as a filling for teeth. Zinc Phosphate, made by mixing zinc oxide with phosphoric acid, has come into use lately as a substitute for the oxychloride in filling teeth. A white precipitate of zinc sulphide is thrown down by the action of hydrogen sulphide on alkaline solution of zinc salts. MAGNESIUM. Magnesium, Mg, 24.3, occurs as carbonate [magnesite), silicate [talc and soapstone), also as hydroxide and chloride. Most natural waters con- tain magnesium compounds. It is a bright, malleable solid. Sp. gr. 1.74. When strongly heated in the air it burns with a bright light, producing MgO. Magnesium compounds cause hardness in water similar to that produced by calcium salts. Magnesium Oxide, MgO, Magnesia, is a light, white powder, insoluble in water, and neutralizing acids. Magnesium Carbonate, MgC03, occurs as a mineral [magnesite). The artificial form, known as magnesia alba, is an oxycarbonate. Magnesium Sulphate, MgS04, Epsom Salt, forms colorless crystals, hav- ing the composition MgS04, 7H20. It is very soluble in water. Magnesium Chloride, MgCl2, resembles zinc chloride in some respects, but does not have the same corrosive action. When mixed with magnesium oxide it sets to a hard mass. Cadmium, Cd, 112, occurs in zinc ores. It is silver-white and crystalline. Sp. gr. 8.6. It melts at 4420 F. (2280 C), and is nearly as volatile as mercury. It is easily dissolved by ordinary acids. CdS is obtained as an orange-yellow precipitate by passing hydrogen sulphide into solutions of cadmium compounds. ALUMINUM. 63 Iron Group.—Strictly this includes only iron, manganese and chromium. They form two series of salts, in which they are respectively dyads and tetrads; the tetrad form acting as a double atom, as explained under iron. Aluminum is included here because it forms a single series of compounds agreeing in many respects with the tetrad series of iron salts. Nickel and cobalt are also included, because of several resemblances to iron. ALUMINUM.. Aluminum, Al, 27, is abundant as silicate, constituting clay and many common rocks. Most building materials are mixtures of aluminum silicate with other silicates. Aluminum is white and not very lustrous, malleable and ductile, sonor- ous and very light; specific gravity, 2.6. It tarnishes slightly in the air, and dissolves rapidly in hydrochloric acid and in caustic alkalies, but not in nitric acid. It melts at 8420 F. (4500 C). Valuable alloys of alumi- num with copper, nickel, silver, etc., are now made by a process of elec- trical decomposition. The alloy of 90 parts of copper with 10 parts aluminum has the color of gold. Aluminum forms but one series of compounds, which possess strong analogies to the tetrad series of iron salts; hence it is generally regarded as forming compounds by the joint action of two tetrad atoms, which act as a hexad, but chemists are not unanimous on this point. Aluminum Oxide, A1203, occurs naturally as corundum, which, when crushed, constitutes emery; finely crystallized, as the ruby and sapphire. It can be prepared by heating ammonium alum; it then forms a white pow- der. In all the anhydrous forms it is absolutely insoluble in water, and almost so in acids and alkalies. Aluminum Hydroxide, A12H606, is a gelatinous white mass, easily soluble in acids and alkalies, and has a strong affinity for organic matter; with organic colors it forms precipitates called lakes. Aluminum Sulphate, A12(S04)3, is now largely used in dyeing and in other operations. It forms a white crystalline mass having an acid reaction. Alums.—The alums are a series of double sulphates. One alum has the formula— A12(S04)3 + K2S04 + 24H20. The aluminum in this compound may be replaced by most of the elements of the iron group. The potassium may be replaced by any element of its 64 INORGANIC CHEMISTRY. group, or by ammonium, giving a series of salts of which the following are examples:— A12(S04)3, K2S04, 24H20.....Potassium alum. Cr2(S04)3, NajjSO^ 24H20.....Sodio-chromic alum. Fe2(S04)3, (NH4)2S04, 24H20.....Ammonio-ferric alum. These compounds all contain the same amount of water of crystallization and all crystallize in octahedra. Bodies giving rise to compounds similar both in composition and in crystalline form are called isomorphous. Common Alum is either potassium alum, or ammonium alum. It dissolves easily in water, the solution being acid to test-paper and strongly astringent. When alum crystals are gently heated they swell up, lose their water of crystallization and fall to a soft white powder—burnt alum. Aluminum Chloride, A12C16, is prepared by heating alumina and char- coal in a current of chlorine:— A1203 4- 3C 4- 6C1 = 3CO + A12C16. Glass, Pottery and Porcelain.—These are mostly mixtures of aluminum, calcium and sodium silicates. Colored glasses are produced by the use of various oxides. Pottery and earthenware are made of clay, glazed with a fusible sodium silicate. Lead silicate is also used. Porcelain is a mixture of feldspar (aluminum and potassium silicate), sand and kaolin, a hydrated aluminum silicate. IRON. Iron, Fe, 56, occurs as oxide, sulphide and carbonate; its compounds occur in small quantities in many rocks and soils; it is taken up by plants; and is an essential constituent of the blood of the higher animals. It sometimes occurs native, especially in meteoric stones. A fine grade, Que- venne's iron, for use in medicine, is made by the action of hydrogen on the sesquioxide. On the large scale, iron ore, which generally consists of an oxide or carbonate mixed with clay, sand and other minerals, is heated in blast-furnaces with coal and limestone. The limestone makes a fusible calcium silicate, slag; the coal takes the oxygen away from the iron. The melted mass is then run out into thick bars, forming pig or cast iron con- taining four or more per cent, of carbon, also phosphorus, sulphur, silicon and other bodies. IRON. 65 Wrought iron contains but little carbon; steel contains about one per cent. of carbon; it is, therefore, intermediate in composition. When pure, iron is very soft, but as found in commerce it has various impurities which give special qualities; carbon gives hardness and fusibility; phosphorus and sulphur give fusibility and great brittleness, and are objectionable. Cast iron melts at about 30000 F. (16490 C). Iron is strongly magnetic and not much affected by dry air, but is oxidized by moist air and easily dis- solved by acids. It forms two series of salts—-ferrous, in which it is a dyad, and ferric, in which it is apparently a triad, but the formulae of the ferric compounds are generally doubled and the iron is regarded as a double atom:— Dyad Iron. Hexad Iron. —Fe— =Fe—Fe= Ferrous salts are generally green; ferric salts brown or red. Ferrous salts are converted into ferric by oxidizing agents. As the ferric salts are written with double formulae, the reaction will always require two molecules of ferrous for one of ferric; thus:— 2FeO 4- O = Fe203. 2FeC03 4- O = Fe2Os + 2C02. To make a normal ferric salt we must add one-half as much of the nega- tive element as the ferrous salt already contains; that is, one molecule of the radicle for every two molecules of the ferrous salt. In making ferric chloride, the complete reaction is— 6FeCl2 4- 6HC1 4- 2HN03 = 3Fe2Cl6 4- 4H20 -f 2NO. Ferrous salts are formed from ferric by the action of reducing agents, especially powdered zinc, nascent hydrogen or sulphurous acid. With ferric chloride and zinc the reaction is— Fe2Cl6 + Zn = 2FeCl2 + ZnCl2. Hydrogen sulphide will also reduce ferric salts:— Fe2Cl6 4- H2S = 2FeCl2 + 2HCI 4- S. Ferrous Hydroxide.—Ferrous hydroxide, FeH202, is formed as a pre- cipitate by the action of caustic alkali upon a ferrous salt. It immediately begins to change by absorbing oxygen, and becomes ferric oxide. Ferric Oxide, Fe203, Red Oxide, Sesquioxide, occurs frequently in small amounts in many minerals, and also as iron ore, called red hematite or 66 INORGANIC CHEMISTRY. specular iron. It may be prepared artificially by heating ferrous sulphate (2FeS04 = Fe203 4- S02 + S03), and is the residue obtained in making Nordhausen sulphuric acid. It is a soft, red powder, difficult to dissolve in acids. The finer grades constitute rouge; the coarser, Venetian red and crocus, are used for paints. Ferric Hydroxide, FejHgOg, is easily formed by adding caustic alkali to Fe2Cl6 + KHO = 6KC1 4- Fe2H606. Ferric hydroxide is a soft, brown mass, insoluble in water, but dissolving easily in acid. Its chief importance is as an antidote to arsenic, for which use it must be freshly prepared. Ordinary iron rust consists of impure ferric hydroxide, which also occurs in an impure condition as brown hematite. Magnetic Iron Oxide, FeO,Fe203, a union of the two oxides, is found as a finely crystallized mineral and valuable ore of iron. It can retain mag- netism, and is occasionally found in a magnetized condition, constituting loadstone. Ferrous Sulphide, FeS, made by fusing iron with sulphur, is a dark, slag- like mass, used as a source of hydrogen sulphide. Iron Disulphide, FeS2, Iron Pyrites, is abundant as a mineral, crystal- lized in brass-colored cubes often mistaken for gold, and hence called fool's gold. It is of no use as an iron ore, on account of the sulphur, but is used as a source of sulphuric acid. Ferrous Carbonate is a valuable iron ore and exists in many (chalybeate) waters. It is produced by mixing ferrous sulphate with sodium carbonate: FeS04 + Na2C03 = FeC03 + Na2S04. In this form, however, and also as dissolved in water, it is prone to oxidation, passing into the condition of ferric hydrate, which forms a red deposit. This oxidation is hindered by sugar. Ferrous carbonate is prepared for medical use by precipitating it in contact with sugar, consti- tuting Vallet's mass. The carbonate occurring naturally in the crystallized form is permanent in the air. Ferrous Sulphate, FeS04, Green Vitriol, Copperas, is formed by dissolv- ing iron in sulphuric acid or by oxidizing iron pyrites. It forms clear green crystals containing FeS04, 7H20, easily soluble in water, the solution being liable to oxidation. Ferric Sulphate.—An oxysulphate (Fe2)2 (S04)50, called Monsel's Salt, or when dissolved Monsel's Solution, is used as a styptic. MANGANESE. 67 Ferric Chloride, Fe2Cl6, is generally seen as an alcoholic solution, some- times called muriated tincture of iron. Ferric chloride is made by boiling ferrous chloride with nitric and hydrochloric acid :— 6FeCl2 4- 6HC1 + 2HN03 = 3Fe2Cl6 4- 4H20 4- 2NO. When the solution is evaporated a red crystalline mass of Fe2Cl6 + 6H20 is formed, which is decomposed by heat. Ferrous salts are usually green, ferric red or brown. The two classes of iron salts can be easily distinguished by certain tests:— Ammonium hydrox- ide, Potassium ferrocyan- ide, Potassium ferricyan- ide, Tannin, Potassium sulpho- cyanate, With Ferrous Salts. Green ferrous hydrox- ide, turning red, Light blue precipitate, Dark blue precipitate. No action, No action, With Ferric Salts. Red ferric hydroxide. Dark blue precipitate No precipitate. Black precipitate. Blood red color, but no precipitate. MANGANESE. Manganese, Mn, 55, exists principally as oxide, also as sulphide, car- bonate and silicate. It is grayish-white, brittle and hard; specific gravity between 7 and 8. It forms two series of salts parallel to those of iron. Manganous Oxide, MnO, and Hydroxide, MnH202, absorb oxygen rapidly. Manganous Chloride, MnCl2, forms pink crystals, deliquescent and solu- ble in water. Manganous Sulphate, MnS04,7H20 is a rose-colored salt, soluble in water, and used in dyeing. Manganese Dioxide, Mn02, Black Oxide.—This is an abundant mineral. It is extensively used as an oxidizing agent and in the manufacture of chlorine. Ordinarily it is in black masses or powder. It conducts electricity. Manganic Oxide, Mn203, is found as a mineral. It is a weak base. Manganese Acids.—Manganese furnishes two acids— H2Mn04 .... Manganic acid. HMn04 .... Permanganic acid. The former has not been obtained, but some of its salts are known. 68 INORGANIC CHEMISTRY. Manganates.—These are formed by fusing manganese dioxide with caustic alkali and potassium nitrate or chlorate. In this way potassium manganate, K2Mn04, is formed as a green crystalline mass. When dissolved in water the manganates turn into permanganates by the follow- ing reaction :— 3K2Mn04 + 2H20 = 2KMn04 4- Mn02 4- 4KHO. The change of composition is indicated by a change of color from green to red. Potassium Permanganate, KMn04, is much used as an oxidizing and deodorizing agent. The solution is decomposed by organic matters by sulphites and sulphides and reducing agents generally, becoming converted into a colorless solution. It can therefore be employed not only to destroy organic matter, but also as an approximate measure of the amount present. CHROMIUM. Chromium, Cr, 52.2, occurs principally as an oxide in combination with iron oxide, constituting chrome iron ore, FeO,Cr2Oa; also as lead chromate, PbCr04. It was discovered by Vauquelin in 1797. It is a hard crystalline mass, not easily oxidized or dissolved. It forms two sets of salts, analogous to those of iron, and also anhydrides. The compounds in which it acts as a positive are of very little importance. The chro- mous salts are unstable. Almost all the chromium compounds are high- colored. Chromic Oxide, Chromium Sesquioxide, Cr203, Chrome Green, is a bright green powder used as a paint. Chromic Anhydride, CrOs, forms bright red crystals, very deliquescent, soluble in water and having powerful oxidizing properties. Potassium Chromate, K2Cr04, forms lemon-yellow crystals soluble in water. Potassium Dichromate, K2Cr20T, commonly known as bichromate, is in large, bright red crystals soluble in water. It is extensively used as a source of various colors. It may be regarded as a salt of dichromic acid, H2Cr207, produced by subtracting one molecule of water from two mole- cules of chromic acid. 2H2Cr04 — H20 = H2Cr2Or NICKEL—COBALT. 69 Lead Chromate, Chrome Yellow, PbCr04, is easily formed by adding a soluble chromate to a lead salt:— Pb(N03)2 4- K2Cr04 = PbCr04 4- 2KN03. It is bright yellow and insoluble in water. Commercial chrome yellow often contains white lead and chalk. A mixture of potassium dichromate and sulphuric acid is used as an oxidizing agent in galvanic batteries. The chromic acid becomes reduced and forms chromic sulphate; the liquid turns green, and afterward deposits dark ruby-red crystals of chrome-alum. K2S04 4- Cr2(S04)3 4- 24H20. Chromates are recognized by their color and the yellow precipitate of lead chromate formed when mixed with lead salts. NICKEL. Nickel, Ni, 59, occurs principally in union with arsenic and sulphur; also in meteoric iron as an alloy. It is hard and white, of specific gravity 8.8, fusing at a high temperature and resisting the action of air at common temperatures. Like iron, it can acquire permanent magnetism. Solution of nickel can be decomposed by an electric current, and nickel-plating is performed in this way. An alloy of copper, zinc and nickel is called German silver. Nickel Monoxide, NiO, and Hydroxide, NiH202, are green and form green salts. Nickel Sesquioxide, Ni203, is also known, but does not appear to form salts. Nickel Sulphate, NiS04, is the most important salt. It usually crystal- lizes with 7 molecules of water. Cobalt, Co, 59, is found associated with nickel, which it closely resembles in properties and chemical relations. Its compounds are mostly red or blue. The element itself is hard, white, magnetic and difficult to fuse; specific gravity, 8.7. The oxides, sulphates carbonates, etc., resemble in composition those of nickel. 70 INORGANIC CHEMISTRY. Nitrogen Group.—This includes"boron, nitrogen, phosphorus, arsenicum, antimony, bismuth and gold, the first and last elements being not quite so marked in their relationship to the others. The members of the group are triads and pentads, sometimes apparently monads. Their oxides are either mostly acid anhydrides or in a few cases feeble bases. The group includes some of the most powerful mineral poisons known. Many of the " ous" compounds of this group may be formulated so as to represent the elements as saturated pentads. Thus nitrous acid may be vn written: H(N02), that is hydrogen directly united to nitrogen. The conversion into nitric acid consists in the formation of hydroxyl, thus: vn H HO(N02). Phosphorous acid may be written : (HO) 2P0, one H not being in the hydroxyl condition. Arsenous acid may also be so explained. The above suggestions agree very well with many of the reactions of the nitrites, phosphites and arsenites, among other points, explaining their tendenqy to take up oxygen. BORON. Boron, B, n, is found in the form of Boric Acid, H3B03, in steam jets in volcanic regions, and also as deposits of sodium or calcium borate. It has been obtained as a dark green powder, and in a crystalline form, resembling the diamond in hardness. Boron is a triad, and bears some resemblance in chemical functions to both carbon and aluminum. Boric Acid, H3B03, Boracic Acid.—This exists in the steam discharged in some volcanic regions, and some of its salts occur as minerals. It forms pearly scales of a bitter taste, soluble in water and alcohol and feebly acid. Heated to 2480 F. (1200 C), it forms metaboric acid, HB02, and on still further heating it is converted into boric anhydride, B203, which fuses to a clear glass. Its salts are called borates. Boric acid is an antiseptic. Several preparations of boric acid or of borates are now in the market as food preservatives. A mixture of boric acid and borax was at one time sold under the name of rex magnus. Such preparations are especially used for preserving milk. A compound prepared by the incorporation of boric acid with glycerin, known as boro-glyceride, is also employed as a preservative. Boric acid has a feeble action on litmus, and turns turmeric paper to a brown-red color. It imparts a bright green color to flame. Borax, Na2B407, sometimes called sodium biborate, is the most familiar compound of boron, and may be regarded as sodium tetraborate. Tetra- NITROGEN. 71 boric acid is not known in the free state, but can theoretically be derived by subtracting one molecule of water from four molecules of metaboric acid. 4HB02 — H20 = H2B407. Borax has the power to take up oxides and re-form metaborates, and, as the compounds are fusible at moderate heat, borax is frequently used in metallurgical operations [e. g., soldering) to clean off the surfaces of metals, which it does by dissolving the oxides. NITROGEN. Nitrogen, N, 14, constitutes about four-fifths of air, and occurs in many animal and vegetable tissues; also as sodium and potassium nitrates. It is a gas without color, taste or smell. It does not burn or support com- bustion, and is not poisonous, but will not support life. At high tempera- ture, and under the influence of electric discharges, it will enter into combi- nation with oxygen, boron, silicon, carbon, hydrogen and magnesium. It is a little lighter than air; a litre weighs 1.25 grms. It can be liquefied only by intense cold and pressure. Nitrogen is generally a pentad; sometimes it acts as a triad, or even as a monad. It is an essential ingredient of all the higher tissues of animals, and exists also in vegetable structures, but not so abundantly. Most of the powerful explosives now in use—gun-cotton and nitro-glycerine, for instance —owe their qualities partly to the nitrogen present. Air.—The atmosphere is an intimate mixture of about four volumes of nitrogen with one volume of oxygen. It surrounds the earth to the height of many miles. Air is dissolved by water, but the nitrogen and oxygen are in a proportion different from that in ordinary air. The composition is not absolutely constant nor in exact atomic proportions, either by weight or volume. That the composition of air varies so little is due to the fact that all gases mingle with one another, so that sooner or later they produce a uniform mixture in spite of the influence of gravity. The rate of mixture depends on the density of the gas. Ordinary air contains small quantities of other substances besides nitrogen and oxygen. It always contains water, carbonic acid and ammonia; fre- quently compounds of nitrogen and oxygen, and also ozone. Besides these we have dust and the products of animal and vegetable decomposition. The study of impurities of air has received much attention of late years, 72 INORGANIC CHEMISTRY. especially in view of the fact that many diseases are due to living organ- isms, or germs which are conveyed in the air. The following may be taken as a fair average of composition :— Oxygen,.....20.61 Nitrogen.....77-95 Carbon dioxide, . .03 Water,.....1.40 Traces of ammonia, nitric acid and marsh gas (CH4), and in towns, sul- phur compounds. 100 cubic inches of air weigh 30.93 grains; I litre weighs 1.29 grammes; 13 cubic feet weigh about 1 ft). At the level of the sea the pressure is, ordinarily about 15 lbs , and will sustain a column of mercury 760 milli- metres, or 30 inches, in height. Water in its natural condition always contains some air in solution. The capacity of air for holding moisture increases rapidly as the tem- perature rises. The dryness or dampness of the atmosphere is not due to the actual quantity of moisture in it, but to the amount present in propor- tion to that which the air can take up. The nearness of air to saturation is called the relative humidity. Air saturated with water has a relative humidity of 100; if half saturated, the relative humidity is 50, and so on. When the temperature falls the moisture separates to a greater or less extent, and produces fog, rain or dew, and if the temperature gets below the freezing point, snow or frost. The respiration of animals and the processes of combination and decay are continually changing the air, by removing oxygen and introducing water, carbonic acid, organic matter, ammonia and hydrogen sulphide. The dust which is always floating in the air contains substances living and dead, and varies with the locality. The continued removal of oxygen is counterbalanced by the action of plants, which, under the influence of light, decompose the carbonic acid, retaining the carbon and giving off the oxygen, especially at the under surface of the leaves. Plants also absorb oxygen and excrete carbon dioxide continuously; this process not depend- ing on light. The nitrogen of the atmosphere is very little affected in these actions. The ammonia and other gases are gradually oxidized or absorbed by the soil and plants and washed out by the rains. The organic matter is also oxidized. Amine, NH3, Ammonia Gas, Ammonia.—Amine is given off in the decomposition of organic matter, especially animal remains, and was origi- nally derived from refuse of this kind. It is also produced by the action of NITROGEN. 73 hydrogen on nitric acid. The great source at the present time is the water which has been used for washing the common illuminating gas. Amine may be obtained by heating a mixture of ammonium chloride (NH4C1,) and lime:— 2NH4C1 4- CaO = 2NH3 4- H20 4- CaCl2. By passing the gas over dry lime the water is absorbed and the pure NH3 is collected. Amine is a colorless gas of a pungent odor. It is absorbed in large amounts by water, one pint absorbing 700 pints of gas and increasing fifty per cent, in volume. This solution exhibits most of the properties of the gas, and is much used under the name of aqua ammonice or solution of ammonia. Amine is lighter than air. 1 litre weighs 0.76 grm. At a tempera- ture of — 400 F. (—400 C), or under a pressure of 100 lbs. to the square inch, it condenses to a colorless liquid. This liquid, of course, evaporates rapidly when the pressure is removed, and produces great cold, which fact has been made use of in machines for making ice. The solution of amine in water has a strongly alkaline and basic power, much like those of potassa and soda. It has received the name of volatile alkali, to indicate this, the others being called fixed alkalies. The compounds produced by it may be considered as formed in the same manner as those of potassium and sodium, these elements being repre- sented by the radicle, NH4. In this way NH3 4- HCl would produce NH4C1; NH3 + H20 would produce NH4HO. NH4 is a radicle called ammonium; its valency is one; it combines with one atom of chlorine and can replace the hydrogen of acids. The following formulae show the comparison between the salts of potas- sium and those of ammonium:— KCl......Potassium chloride. NH4Cl.....Ammonium chloride. K2S04.....Potassium sulphate. (NH4)2S04 . . . Ammonium sulphate. KN03.....Potassium nitrate. NH4N03 .... Ammonium nitrate. KHO.....Potassium hydroxide. NH4HO .... Ammonium hydroxide. Ammonium, NH4, has not been obtained in the free state. •Ammonium Hydroxide, NH4HO, the result of the solution of amine 6 74 INORGANIC CHEMISTRY. gas in water, is a colorless liquid, corrosive, poisonous, powerfully alkaline and pungent. Ammonium Carbonate, (NH4)2C03, is not generally seen. The body sold as ammonium carbonate is a mixture of acid ammonium carbonate with ammonium amido-carbonate (see under amido-compounds), therefore, NH4HC03 + NH4 (NH2C02). It is often called sesquicar- bonate, or smelling-salt. It is a white body, soluble in water, and smelling strongly of amine. By exposure to air it is converted into acid carbo- nate, NH4HC03. Ammonium Nitrate, NH4N03, is a white solid, very soluble in water. Its chief use is for making nitrous oxide. Ammonium Sulphate, (NH4)2S04, is used as a fertilizer and in the manufacture of alum. Ammonium Chloride, Sal Ammoniac, NH4C1, is a white solid, crystal- lizing in cubes, and is very soluble in water. It has many uses. Ammonium Bromide, NH4Br, and Ammonium Iodide, NH4I, are used in photography and medicine. If dry ammonium compounds be heated with lime, amine is quickly evolved, and may be recognized by its odor, alkaline reaction and the white cloud of NH4C1 produced by hydrochloric acid. The most delicate test for ammonium is Nessler's reagent, a solution made by mixing HgCl2, KI and KHO or NaHO. This produces, with very minute quantities of am- monium, a yellow color. One part in fifty million parts of water can be recognized. Nitrogen Oxides.—Five compounds of nitrogen and oxygen have been obtained:— N20 . . . Nitrous oxide, laughing gas. NO . . . . Nitric oxide (often written N202). N203 . . ■ Nitrous anhydride. N20 . . . Nitrogen peroxide (often written N204). N205 . . . Nitric anhydride. The names of these compounds are confused. Thus, NO is often written N202. and called nitrogen dioxide. N02 is written N204, and called nitro- gen tetroxide. Nitric Acid, Aqua fortis, HN03, is made by the action of strong sul- phuric acid upon nitrates. The reaction with sodium nitrate is__ 2NaN03 4- H2S04 = Na2S04 4- 2HN03. NITROGEN. 75 Nitric acid thus obtained has the composition HN03; when quite pure it is colorless. The commercial acid has the composition 2H20 + HNOa. It is a strongly acid liquid, highly corrosive and poisonous and of high oxidizing power. One-half the oxygen of the acid is available. The effect is in most cases represented thus:— 2HN03 decomposes into H20 + 2NO 4- 03. The 03 is the available oxygen. With some bodies the acid acts simply by exchanging its hydrogen. Thus:— Zn 4- 2HN03 = Zn(N03)2 4- H2. The evolved hydrogen, however, often attacks another portion of nitric acid and forms ammonium nitrate. If basic oxides are formed by the oxidizing action of nitric acid, they will unite with another portion of the acid to form nitrates. In the case of copper, the following reactions take place:— Oxidation of the copper occurs first— t Cu3 + 2HN03 = 3CUO 4- H20 4- 2NO. The CuO then acts upon other nitric acid— 3CuO 4- 6HN03 = 3Cu(N03)2 + 3H20. The complete reaction is, therefore, 3Cu 4- 8HN03 = 3Cu(N03)2 4- 4H20 4- 2NO. Tin gives the following:— Sn3 4- 4HN03 = 3Sn02 4- 2H20 4- 4NO. Sn02 is not basic, and therefore does not form a nitrate, as copper oxide would. Instead of this, the tin dioxide takes water and forms an acid. Many organic bodies are oxidized by nitric acid. Another action of nitric acid is in forming substitution compounds. When benzene, C6H6, is treated with strong nitric acid, one atom of hydro- gen is removed and one molecule of N02 put in its place. We have— C6H6 4- HN03 = C6H5(N02) 4- H20, and the body so formed is called Nitrobenzene. A mixture of nitric and sulphuric acids is often used for such effects. Very strong nitric acid fails to act upon some substances which are readily attacked by the more dilute forms. The strong acid produces yellow stains on organic matter. 76 INORGANIC CHEMISTRY. Free nitric acid colors morphia red; copper is dissolved by it, with the production of red fumes of N02. Nitrous Oxide, N20, laughing gas, sometimes called nitrogen monoxide. This is obtained from ammonium nitrate, which, when carefully heated, decomposes completely into nitrous oxide and steam:— NH4NOs = N20 4- 2H20. It is a colorless, odorless gas, with a somewhat sweetish taste. When the gas is inhaled freely, a short insensibility is produced. It supports com- bustion. At a pressure of fifty atmospheres it becomes a colorless liquid, and is now sold in this form compressed in strong metal cylinders. Nitrous oxide may be regarded as the anhydride of hyponitrous acid, HNO, several derivatives of which have been described. Nitric Oxide, NO, often called nitrogen dioxide and written N202, is a frequent product of the action of nitric acid. Thus, with copper we have— Cu, + 8HN03 = 3Cu(N03)2 4- 4H20 4- 2NO. Some N20 is often produced in this experiment. NO is a colorless gas, but when brought in contact with oxygen it instantly absorbs one atom, becoming N02 and turning brownish-red. Nitrogen Dioxide, N02, Nitrogen Peroxide.—These various names are owing to uncertainty in the chemical relations of the body. It has also been called nitrogen tetroxide (being written N204) and hyponitric acid, and by other less common names. The proper name is nitrogen dioxide, to corres- pond to the formula N02. It is a brownish-red gas, easily condensed to the liquid form and readily absorbed by water. Nitrous anhydride, N203, and nitric anhydride, N205, are unimportant, as is also nitrous acid, HN02. Nitrites are frequently found in river and well water. PHOSPHORUS. Phosphorus, P, 31, occurs principally as calcium phosphate, which exists in bones and teeth, and in many minerals. Phosphates also exist in the fluids of the animal body. Phosphorus is generally prepared from bones, which contain from one- third to two-thirds their weight of calcium phosphate. The bones are burned, and from the bone-ash the phosphorus is obtained. Phosphorus is usually seen in colorless, almost transparent sticks, soft as wax; when kept for some time, especially in the light, it becomes brown- PHOSPHORUS. 77 ish, opaque and harder. It is kept under water. It takes fire easily, and burns with a bright flame, producing white clouds of phosphoric anhydride, P205. Exposed to the air at low temperature, it can still undergo a slow combustion, producing P203; it is then luminous in the dark. It is insoluble in water, but dissolves in oils and in carbon disulphide. It is extremely poisonous, death having occurred from less than ^ grain. Phos- phorus melts at m° F. (430 C), and boils at 550 F. (2880 C). By keeping it at a temperature of 4500 F. (2320 C.) for some hours, in a closed vessel, phosphorus is converted into the amorphous or red phos- phorus, an allotropic form, which is red, insoluble in carbon disulphide, difficult to burn, non-poisonous, and shows many other minor differences. Its composition is the same. This change is also produced by adding a small quantity of iodine to common phosphorus. ; The uses of the element in matches and as a medicinal substance are well known. In all experiments with it great care must be taken, as it is easily in- flamed and produces one of the most severe forms of burns known. It should be handled with a pair of forceps and cut or divided only under water. Phosphorus acts as a triad or pentad; its affinities in the free state are very high. It is a powerful reducing agent. In very minute quantity it is detected by its luminosity when distilled in a dark room. Hydrogen Phosphide, PH3 Phosphine.—This body is formed under con- ditions analogous to those which produce amine. When a solution of caustic alkali is boiled with phosphorus, hydrogen phosphide is formed. The reaction is— 3NaHO 4- 3H20 + P4 = 3NaH2P02 4- PH3. NaH2P02 is sodium hypophosphite. Hydrogen phosphide is a colorless gas of a disagreeable odor. As ordinarily made it is spontaneously inflam- mable, but this is due to the presence of a small quantity of the vapor of a liquid phosphide, PH2, phosphidogen. If this latter be removed by passing the fresh gas through a tube placed in a freezing apparatus, the power of spontaneously inflaming is lost. Hydrogen phosphide forms many compounds analogous to those formed by amine. Compounds of Phosphorus with Oxygen.—Only two compounds are defi- nitely known. These are:— P203 .... Phosphorous anhydride or phosphorous oxide. P205 .... Phosphoric anhydride or phosphoric oxide. 78 INORGANIC CHEMISTRY. Phosphorous Anhydride, P203, is produced by the slow oxidation of phosphorus. Phosphoric Anhydride, P205.—This is easily produced by burning phos- phorus in the air. It is a snow-like solid, which rapidly absorbs water. It is capable of uniting with water in at least three proportions, forming different bodies. The combination is shown in the following equations:— p205 _j_ H20 = 2HP03 .... Metaphosphoric acid. P205 + 2H20 = H4P207 .... Pyrophosphoric " P205 + 3H20 = 2H3P04 .... Orthophosphoric " The third acid is the one that yields all the natural phosphates. Metaphosphoric acid is distinguished by the power of coagulating albumin. Although the three phosphoric acids differ in oxygen, the ter- mination " ic" is not changed. This is because they are all formed from the same anhydride; the difference in oxygen is due to the amount of water, and all contain pentad phosphorus. The number of salts formed by each acid is in proportion to the number of molecules of water which it has taken up. Metaphosphoric acid, produced by adding one molecule of water, gives one series of salts:— NaP03............Sodium metaphosphate. Ca(P03)2...........Calcium " Pyrophosphoric acid, produced by adding two molecules of water, gives two series of salts, acid and normal:— Na2H2P207 . . . Acid sodium pyrophosphate. Na4P207 .... Sodium " Orthophosphoric acid, produced by adding three molecules of water, gives three series of salts, di-acid, acid and normal:— NaH2P04 .... Di-acid sodium orthophosphate. Na2HP04 .... Acid " « Na3P04.....Sodium orthophosphate. The phosphates of the potassium group are soluble in water. Almost all others are insoluble in water, but soluble in acids. Silver nitrate produces with orthophosphates a yellow precipitate soluble in ammonia. A solution of ammonium molybdate in nitric acid gives a bright yellow precipitate. This is a very delicate test. Two phosphorus chlorides are known, PC13 and PC15. ARSENICUM. 79 ARSENICUM. Arsenicum, As, 75, occurs in the free state and as sulphide, also in com- bination, especially with nickel, cobalt and iron. It is rather abundant, and exists in small amounts in many minerals. It is often called arsenic, but arsenicum is a preferable name. It is prepared by deoxidizing arsenous anhydride by charcoal:— As203 4- C3 = As2 + 3CO. When freshly prepared, it is a steel-gray, brittle mass with a decided lustre. It tarnishes somewhat in the air, and passes into vapor at about 3560 F. (1800 C.) without fusing. Heated in contact with air, it oxidizes to arsenous anhydride, and develops a garlicky odor. It is not dissolved by any simple solvent. Arsine, AsH3, Arseneted Hydrogen.—This body is analogous to amine; its formation is a delicate test for arsenic. The usual method of preparation is to liberate hydrogen in a solution of arsenous anhydride. It is a com- bustible gas of disagreeable odor and excessively poisonous. Compounds of Arsenicum with Oxygen ;— As203.....Arsenous oxide or anhydride. As2Os.....Arsenic " " Arsenous Anhydride, As203, Arsenous Oxide, White Arsenic.—This substance is often called arsenic. It presents itself in commerce in two Varieties: [a) The vitreous form, transparent and colorless at fir^t, but after- ward becoming yellowish and porcelain like; [b) A pulverulent form, which is distinctly crystalline. Arsenous anhydride is a white solid, odorless and tasteless, dissolving with difficulty and only in small amounts in cold water; the solution is feebly acid, and is supposed to contain arsenous acid, H3As03. Hot water is a more active solvent. A fluidounce of cold water will dissolve about one grain, and the same amount of water if kept for one hour at the boiling-point will take up forty grains. In acid and alkaline solutions it dissolves much more readily. Heated to 3800 F. (1930 C), the solid passes into vapor without fusing, and if allowed to condense produces brilliant, transparent crystals. It is intensely poisonous in all its forms, a few grains being a fatal dose. Arsenous anhydride is used in medicine, in various solutions for preserving animal skins, and in the manufacture of 80 INORGANIC CHEMISTRY. colors. Its frequent occurrence and poisonous qualities have made its pro- perties and tests of great importance. The following is a brief summary of the methods used. I. Reduction Test.—A small quantity of powdered white arsenic is mixed with some dried potassium ferrocyanide and heated in a narrow glass tube. The arsenicum is set free, rises in vapor, and condenses on a cooler portion of the tube, as a dark steel-gray but rather lustrous layer, called the arsenical mirror. If this deposit be heated, it may be driven further along the tube, and will finally oxidize and produce the garlicky odor. 2. Sublimation Test.—Arsenous oxide heated alone passes quickly into vapor, and by allowing this vapor to condense upon a slightly warmed part of the tube fine crystals are formed. Under the microscope these crys- tals are seen to be octahedral ; that is, consist of eight triangular faces, though they are rarely completely formed. Very minute quantities of arsenic can be recognized by this test. 3. Reinsch's Test.—This is the most valuable test, because it can be applied to impure mixtures, as the contents of a stomach. A small quan- tity of water is put into a wide test-tube or porcelain basin; some hydro- chloric acid is added; a piece of clean copper is put in and the water brought to boiling. A few drops of a solution of arsenic are now added, and in a few seconds a rather dull, steel-colored deposit of copper arsenide forms on the copper. When this deposit has become rather dense, the copper is taken out, dried with filter paper, rolled up intp small bulk and placed in the end of a small glass tube. Heat being applied, the arsenical deposit is oxidized and volatilized, forming octahedral crystals of arsenous anhydride. 4. Marsh's Test.—This depends on the power of nascent hydrogen to form AsH3. The hydrogen is obtained either by the action of sulphuric acid upon zinc or magnesium, of sodium amalgam on water, or by a cur- rent of electricity. AsH3 is combustible. If a cold porcelain plate be held in the flame, an arsenical soot will be deposited as a brown shining stain. If the tube which is conducting the current be heated, the gas will be decomposed and a similar stain formed within the tube. The stains may be identified by the fact that they are : [a) easily volatile; [b) soluble in a solution of bleaching-powder; [c) capable of producing octahedral crystals of As2Os. Three tests, known as the liquid tests, are applicable only to pure solu- tions of arsenous anhydride. They are— ANTIMONY. 81 I. Hydrogen sulphide produces a lemon-yellow precipitate of arsenous sulphide, As2S3:— As203 4- 3H2S = As2S3 + 3H20. A few drops of hydrochloric acid facilitate the action. 2. Silver nitrate, made feebly alkaline by ammonium hydroxide, gives a yellow precipitate of silver arsenite. 3. Copper sulphate, made feebly alkaline, gives a green precipitate of copper arsenite. Arsenic Anhydride, As205.—This is produced by oxidizing arsenous anhydride with nitric acid. It forms, with water, arsenic acid, H3As04, which is used as an oxidizing agent in the manufacture of aniline colors. This use has been supposed to account for the cases of skin irritation which have been occasionally observed to follow the wearing of goods dyed with these colors, but it is doubtful if any of the poison ordinarily remains in the manufactured fabric. Arsenic acid forms salts called arsenates. Three forms of arsenic acid are known, corresponding to the three forms of phosphoric acid. Compounds of Arsenicum and Sulphur.—Three of these are known :— AsS .... Arsenic monosulphide, realgar. As2S3 . . . Arsenous sulphide, orpiment. As2S5 . . . Arsenic " Realgar is a brick-red solid, easy volatile. It may be considered as analogous to NO. It is often written as As2S2. Orpiment, King's yellow, is found as a mineral and is easily produced artificially by the action of hydrogen sulphide upon arsenous compounds. It is a bright yellow solid, fusible and volatile, soluble in alkalies, but insoluble in water and dilute acids. It is often obtained in the process of testing for arsenic, and in the arts is used as a pigment. Arsenicum forms chlorides, bromides and iodides, but they need not be described. ANTIMONY. Antimony, Sb, 122, occurs sometimes in the free state, but generally as sulphide, Sb2S3. It is also called Stibium. Antimony is bluish-white, brittle, generally highly crystalline and of brilliant lustre. It fuses at 8420 F. (4500 C), and volatilizes at a red heat. On cooling from the melted condition it expands somewhat, and 82 INORGANIC CHEMISTRY. some of its alloys retain this property, for which reason it is used in type- metal and other alloys which must take sharp casts. Like arsenic, it is not soluble in any simple solvent. The chemical relations of antimony are much like those of arsenic, phosphorus and nitrogen. It forms an oxide which is slightly basic. Antimony is detected by tests similar to those of arsenic. The distinctive differences are:— I. The sublimate of free antimony cannot be obtained by the reduction test unless a very high temperature be used. 2. The antimony oxide cannot be volatilized except by a high heat, and does not usually form octahedral crystals, but these have been obtained under certain conditions. 3. The copper slip in Reinsch's test becomes covered with a bluish or violet deposit, which gives a sublimate only with great difficulty. 4. In Marsh's test a much darker spot is obtained; it is volatilized with difficulty, and not dissolved by a solution of bleaching powder. 6. The liquid tests give no result except with hydrogen sulphide, which produces an orange-red precipitate. Stibine, Anlimoneted Hydrogen, SbH3, resembles the corresponding arsenic compound, and is produced under similar conditions. It has not been obtained pure. Compounds of Antimony with Oxygen.—These are :— Sb203.....Antimonous oxide, or anhydride. Sb205.....Antimonic " " An intermediate oxide, Sb204, probably a mixture of the other two, is known. Antimonous Oxide, Sb203.—This is found as a mineral, and is also readily prepared by burning antimony in the air. It is like As203 in many of its chemical relations, but is insoluble in water, less volatile, and shows some power of combining with acids to form salts. When boiled with a solution of cream of tartar (acid potassium tartrate) antimonous oxide loses one atom of oxygen, and dissolves, forming tartar emetic, potassium anti- mony tartrate. This compound is the most familiar preparation of antimony, as it dissolves in water without decomposition. The composition is excep- tional; acid potassium tartrate is KHC4H406, and the reaction with anti- monous oxide is— 2KHC4H406 4- Sb203 = 2K(SbO)C4H406 4- H20. The SbO replaces the hydrogen. ANTIMONY. 83 Boron or arsenicum may take the place of antimony in this compound. Anlimonic Oxide, Sb205, forms two acids corresponding to the meta- and pyrophosphoric acids: HSb03, metantimonic, and H4Sb207, pyranti- monic acid. Pyrantimonic acid is remarkable for forming a sodium com- pound insoluble in water. Antimony forms compounds with chlorine, bromine and iodine analogous to those of phosphorus and arsenic. They are mostly decomposed when mixed with large quantities of water, yielding at first an impure, finally a pure, oxide. With antimonous chloride we have— 3SbCl3 4- 3H20 = SbCl3Sb203 4- 6HC1. The oxychloride, SbCl3Sb203, becomes finally converted into pure anti- monous oxide. Antimony Sulphides.—Two are known :— Sb2S3.....Antimonous sulphide. Sb2S5.....Antimonic sulphide. Antimonous Sulphide is the principal ore of antimony. It is found as a shining, gray, crystalline mass, fusible and easily oxidized by heating in the air. Hydrochloric acid dissolves it easily, forming antimonous chloride and hydrogen sulphide:— Sb2S3 4- 6HC1 = 2SbCl3 4- 3H2S. On the other hand, a current of hydrogen sulphide passed into antimony solutions produces the antimonous sulphide as an orange-red precipitate, which by heating becomes like the natural form. Antimonic Sulphide is an orange-yellow body. The chemical relations of antimony are well shown in its sulphides. Both of them act as anhydrides, and form a series of salts. KSbS2.......Potassium sulphantimonite is strictly comparable to KN02.......Potassium nitrite. Antimonic sulphide, forms salts upon the pattern of the ortho-phosphates. Na3SbS4......Sodium sulphantimonate is analogous to Na3P04......Sodium orthophosphate. Sodium sulphantimonate is used in photography under the name of Schlippe's salt. 84 INORGANIC CHEMISTRY. BISMUTH. Bismuth, Bi, 208, is commonly found native; also as oxide and sul- phide. It is hard, brittle, reddish-white and distinctly crystalline. It fuses at 5070 F. (2640 C), expanding when it solidifies. It is not much affected by the air. Nitric acid dissolves it. Bismuth Sesquioxide, Bi203, the only important oxide, is obtained as a yellowish powder by burning bismuth in the air or by heating the carbonate or nitrate. It. acts as a base. Bismuth Nitrate, Bi(N03)3, made by dissolving bismuth in nitric acid, is a soluble, white, crystalline mass. When added to a large volume of water, a white precipitate of bismuth oxynitrate, of irregular composition, but generally BiN030 is thrown down. This powder, ordinarily called bismuth subnitrate, is used in medicine and sometimes as a cosmetic. When it is boiled with caustic soda and a solution of glucose, a heavy black powder of free bismuth is formed. This is Boettger's test for sugar. Bismuth Chloride, BiCl3, is decomposed by water in a manner similar to the nitrate, producing an oxychloride. Bismuth Subcarbonate, a compound of irregular composition, is used in medicine. GOLD. Gold, Au, 196.7, occurs in the free state, often in veins in quartz, often in small grains in sand and gravel; sometimes alloyed with silver, copper or other bodies. Pure gold is very heavy (specific gravity, 19.4), capable of being worked into thin plates or wire, and an excellent conductor of heat and electricity. The ordinary yellow appearance is due to much admixed white light. The true color, red, is obtained by repeated reflections. It melts at 19000 F. (10360 C). It is unaffected by air, water, sulphur, or by ordinary acids, even at high temperatures. Its compounds are reduced by heat, and by reducing agents in the cold. Chlorine or a mixture of nitric and hydro- chloric acid (which contains free chlorine) dissolves it, forming chloride. In the pure condition it is very soft and can be welded in the cold by pressure. Gold-foil is prepared in this form for dentists' use. For articles subjected to wear it is alloyed with copper or silver. The proportion of alloy is indicated by carats, pure gold being 24 carats, 18-carat gold being VANADIUM. 85 18 parts gold and 6 parts alloy. Copper makes a red gold; silver, a green gold. The United States coin gold contains 90 per cent, of gold alloyed with copper and silver. Two sets of compounds are known, aurous and auric", in which the metal is respectively a monad and a triad. The oxides are not bases; one appears to be an anhydride. Au,0 . . Aurous oxide. Au203 . . Auric " AuCl . . Aurous chloride. AuCl3 . . Auric " Auric Chloride is produced when gold is dissolved in nitro-muriatic acid. By adding to the liquid, free from excess of acid, some ferrous sulphate, the gold is thrown down as a brown powder. A mixture of stannous and stannic chlorides produces with gold chloride a purple precipitate called purple of Cassius, used for coloring glass and porcelain. Vanadium, V, 51.3, is a rare body, found chiefly in combination with iron and lead. It forms four oxides. VO, V203, V02, V205. Vanadic Anhydride, V205, forms salts called vanadates. Lead vanadate is found as a mineral. It yields compounds analogous to metaphosphoric acid, and also forms salts with some of the strong acids. Vanadium has acquired some importance from the possibility of making from it a good indelible ink, but the rarity of its compounds has interfered with this use. 86 INORGANIC CHEMISTRY. Carbon Group.—This includes carbon, silicon, tin and titanium. They are tetrads, neither strongly positive nor strongly negative in character. With the exception of carbon and silicon they form feebly basic oxides. All of them form acid anhydrides. Platinum may also be placed iii this group. CARBON. Carbon, C, 12, occurs very abundantly in nature. It is so constant a component of organic bodies that organic chemistry has been called the chemistry of .the compounds of carbon. In the tissues of animals and plants it exists in union with hydrogen, oxygen and nitrogen. The various forms of coal and graphite, and certain carbonates, especially of calcium and magnesium, are abundant minerals. Carbon presents itself under several allotropic forms. Amorphous Carbon, such as lampblack and charcoal. Graphite, or Plumbago, a crystalline form. Diamond, also crystalline, often chemically pure. These forms are insoluble in all ordinary liquids, infusible and unacted upon by acids and alkalies or by the air at ordinary temperatures. Heated strongly in air or oxygen, they burn, producing CO or C02. Lampblack is the deposit from smoky flames. It generally contains hydrogen. Wood charcoal contains hydrogen and the mineral substances of the wood. Animal charcoal is obtained by charring animal tissues. Wood and animal charcoals have great powers of absorption—the former for gases, the latter for organic matters, especially color and bitter principles. This property of wood charcoal explains its use as a deodorizer. Gases containing hydrogen, sulphur or phosphorus are generally entirely decom- posed when absorbed by charcoal. If a solution of some organic color, such as litmus or cochineal, be filtered through animal charcoal, the color will be partly or wholly removed. Bitter principles, such as strychnine or the bitter of hops, will also be removed. Animal charcoal is extensively used for the decolorization of syrups and vegetable infusions generally. Graphite, called also plumbago and black lead, is destitute of any absorbent properties, and is used for lead-pencils and for crucibles. CARBON. 87 Diamond is a crystalline form of carbon. It is the hardest substance known, and has been used with great advantage for the drilling and cutting of stone. The specific gravity, color and hardness, are different in the various forms of carbon. Coal has been formed from organic matter. Bituminous or soft coals are first produced. They contain hydrogen and oxygen. Coke is the residue after heating the coal. Anthracite coal is much harder, and has very little hydrogen. It yields no gas on heating. Carbon is a tetrad, and combines with many elements. Compounds of Carbon with Hydrogen.—Hydrogen and carbon combine in many proportions. Coal Gas.—When bituminous coal is heated in a closed vessel, a large amount of gas is given off. This gas, after being purified, constitutes illu- minating gas—a mixture of hydrogen, marsh gas, CH4, defiant gas, C2H4, and other gases. Compounds of Carbon with Oxygen.—The important ones are— Carbon monoxide......CO. Carbon dioxide . . . \ Carbonic anhydride . J 2" Carbon Monoxide, Carbonic Oxide, CO.—This is produced when car- bon is burned in a deficient supply of air, as in stoves with defective draft and in the large furnaces for reducing and working iron, in which an excess of fuel is purposely maintained. When steam is thrown upon hot coal a mixture of carbon monoxide and hydrogen is produced. This is available as a gaseous fuel, or may be impregnated with vapors of gasoline and used as a source of light. It is generally called water-gas. For ex- perimental purposes the action of sulphuric acid upon oxalic acid or upon potassium ferrocyanide is used for the preparation of CO. Carbon monoxide is a colorless, odorless, tasteless gas, of decidedly narcotic poisonous properties. It is a little lighter than air. It burns easily with a clear blue flame. It is an unsaturated molecule, and will combine with chlorine and some other elements. By reason of its unsatu- rated condition, it has the power to unite firmly with haemoglobin, and prevent the proper oxidation of the blood, thus producing, when inhaled, a persistent asphyxiated condition. Carbon Dioxide, Carbonic Anhydride, C02, often wrongly called carbonic acid, is an abundant substance occurring in air and water. Some of its 88 INORGANIC CHEMISTRY. compounds, especially calcium and magnesium carbonates, are common minerals. Carbon dioxide is produced in a great variety of ways:— I. By the respiration of animals; 2. By ordinary combustion; 3. By fermentation and decay; 4. By decomposition of carbonates, either by heat or by acids. The reaction in the case of chalk and hydrochloric acid is— CaC03 4- 2 HCl = CaCl2 + H20 4- C02. It is unimportant whether we regard the water and C02 as separate or united to form carbonic acid, H2C03. By passing the escaping gas over dry calcium chloride or strong sulphuric acid the pure C02 may be col- lected. Properties.—Carbon dioxide is a colorless gas of a somewhat sharp taste. It is soluble at ordinary pressure in its own bulk of water, and the solubility is increased in proportion to the pressure. It is about fifty per cent, heavier than air. I litre weighs 2.07 grms. It can be liquefied by a pressure of 550 lbs. to the inch, and freezes at — 700 F. (— 560 C). It does not support animal life nor ordinary combustion; but bodies of high affinity, if already in active combustion, will decompose it and continue to burn. Red-hot coal will produce the following reaction: C 4- C02 = 2CO, which accounts for the-production of carbon monoxide in ordinary stoves. A lighted taper put into the gas is instantly extinguished, but a slip of ignited magnesium will continue to burn and deposit carbon. The reaction is Mg2 4- C02 = 2MgO -f- C. Lime-water is instantly rendered turbid by the gas, from the formation of insoluble calcium carbonate, thus constituting a test for the gas. Carbon dioxide has a tendency to accumulate at low levels if produced in large amounts. It is found in undue proportions at the bottom of mine- shafts and in fermenting vats. Cases of suffocation often occur in these places. The usual method of determining whether such places are safe to enter is by lowering a lighted candle ; if this continues to burn vigorously, the air is probably safe; if it bums feebly or is extinguished, the air is too rich in the gas. Carbon dioxide is one of the most important agents in the slow changes which occur in nature. Assisted by the action of frost, it breaks down and renders soluble many kinds of rocks and converts them into soils. The ordinary effervescing soda-water is an artificial solution of the gas under pressure. Fermenting liquids owe their effervescence to the same cause. CARBON. 89 Under the influence of light, plants decompose it, the carbon being absorbed and the oxygen given off. Carbonic acid forms a series of salts called the carbonates, most of which are insoluble in pure water. Monads form two salts. Potassium gives us— KHC03.....Acid potassium carbonate. K2COs......Potassium carbonate. Dyads give one salt— CaC03.....Calcium carbonate. Carbonic acid is easily recognized by its rendering turbid a solution of calcium hydroxide (lime water) or barium hydroxide (baryta-water). It turns litmus to a wine-red, the blue color being restored on boiling. Combustion and the Structure of Flame.—Carbon, hydrogen, oxygen and nitrogen are the especial elements of the tissues of animals and plants from which our fuel and illuminating agents are indirectly derived. The process of burning is the absorption of oxygen and the formation of car- bonic acid, water and free nitrogen, and sometimes small amounts of amine and nitric acid. Ordinary flame is gas of some kind in the process of uniting with the oxygen of the air. Formerly the terms "combustible" and "supporter of combustion" were much used; carbon, phosphorus and hydrogen being called combus- tible elements, oxygen and chlorine supporters of combustion. This dis- tinction is now abandoned; the action is a mutual one, and the supporter of combustion may easily be made the combustible. If we examine common gas or candle flame, we find that it consists of three parts: [a) an inner space of a blue color, [b) a shell of brightly luminous particles, [c) a fringe of feebly luminous particles. The inner part is the point at which the gas that is burning is produced or escapes. This generally consists of carbon and hydrogen. At its outer edge it meets the air; most of the hydrogen is converted into water, the carbon is set free in a finely divided condition in union with some hydro- gen and this solid is intensely heated by the combustion of the hydrogen. This is the source of the light, and forms the second part. The finely- divided matter passes outward and gradually burns, producing the feeble fringe of light, which is the third part. It is obvious that with bodies which are deficient in carbon, or which are burned in a supply of oxygen sufficient to consume the carbon before it can be set free, very little light will be produced; on the other hand, if the quantity of carbon is large, the 7 90 INORGANIC CHEMISTRY. flame will not be able to heat it above a red heat, and the supply of oxygen may not be sufficient to burn it up; and we then have a lurid, smoky flame. Alcohol, which contains little carbon, burns without much light; turpen- tine, which contains much carbon, burns with a red flame and smoke. By making a mixture of the two a good flame may be obtained. Anything which cools the carbon down below its burning-point will cause it to deposit in the solid form; hence the formation of soot or lamp- black when flames come in contact with cold surfaces. If a chimney is placed over a smoky flame, the increased draft causes a more abundant supply of air, and the carbon is completely burned. This is the reason for the use of chimneys in oil lamps. If a flame be suddenly cooled, as by the introduction of a coil of wire or a sheet of wire gauze, the combustion will cease and the mixture of gas and air will escape. This can be easily shown by putting a piece of wire gauze across a gas flame, when it will be found that the flame will stop at the gauze, but a combustible mixture of gas and air will pass through it. Similarly, the gas may be lighted above the gauze and the flame will not run back. If the gauze becomes hot,, the flame will pass through. This principle is made use of in the Davy's safety-lamp for preventing explosions in mines. It consists of a lamp arranged so that no air or gas can get in except through fine gauze. If an explosive mixture find its way to the flame, its combustion is limited to the interior of the lamp, at least for a time. If common coal gas be mixed with air, it will burn with a non-luminous, smokeless flame; and such lamps are now used very largely. In the sim- plest form, the Bunsen burner, the air is drawn in through openings at the bottom. A great variety of these lamps is now made. Mr. Fletcher, of England, has brought the use of gaseous fuel to high perfection. When a current of air is driven into a flame its temperature is increased. This is the cause of the efficacy of the mouth blowpipe and of blast-lamps. When mixtures of gas and air are ignited, combustion may occur through the entire mass at once. This constitutes an explosion. Recent research has shown that violent explosions may occur from the rapid ignition of fine particles of coal, flour or other combustible material diffused through the air. Flame Tests.—Many elements give characteristic colors to flames. Such tests are very delicate, and when applied to pure substances very satisfactory. When several colors are present, one color may conceal the other, and thus the test be incomplete. By passing the light through a prism the colors are separated, and each may be recognized. The appa- SILICON. 91 ratus for this purpose is called a spectroscope. Observations with it show that most elements give out light which is made up of several colors. Carbon Disulphide, CS2.—This body is precisely analogous to carbon dioxide. It is produced by passing vapor of sulphur over red-hot char- coal. It is a colorless liquid, which, when quite pure and in large quan- tity, has a rather pleasant odor, but when impure, and especially when diffused through the air in small quantity, is quite disagreeable. It is very volatile and inflammable, and has high solvent powers, dissolving sulphur, phosphorus and most oils and fats, and is much used for such purposes. Its vapor will take fire much below a red heat. Carbon Chloride.—Carbon forms several compounds:— Marsh gas, CH4, for instance, yields, by successive substitution action, the following compounds:— CH3C1 .... Monochlorinated marsh gas. CH2C12 . . . Dichlorinated " " CHC13 .... Trichlorinated " " CC14.....Tetrachlorinated " " The third body, CHC13, is chloroform; the fourth is carbon tetrachloride. Cyanogen, CN.—Cyanogen is a radicle, and in its chemical relations re- sembles such elements as CI, Br and I. It forms compounds called cyanides. In all of these it acts as a monad; thus we have hydrogen cyanide, HCN," potassium cyanide, KCN. Dyads require two molecules of cyanogen. Calcium cyanide is CaC2N2 or Ca (CN)2. The symbol Cy is often used in formulae instead of the symbol CN. We may Write HCy instead of HCN, KCy instead of KCN. SILICON. Silicon, Si, 28, occurs very abundantly as oxide, Si02, and as silicates. Silicon exists in three forms, amorphous, graphoidal and diamond, cor- responding to those of carbon. When strongly heated in the air it burns, producing Si02. Silicon is a tetrad, and is related to carbon in many ways, especially in assuming allotropic forms. Compounds have been obtained in which it has replaced carbon. Silica, Silicic Anhydride, Si02.—This is a widely distributed body, occurring free as common sand, chalcedony, quartz, etc., and in combina- tion forming silicates in great variety, of which clay, granite, feldspar and 92 INORGANIC CHEMISTRY. sandstones are instances. A very large proportion of the solid substances in the earth's crust is in the form of compounds of silica. Silica exists in the stems of grasses and in the teeth and bones of animals. In its pure forms silicic anhydride is a colorless, nearly infusible and in- soluble solid, destitute of chemical activity. In nature it often occurs in large six-sided crystals, called quartz or, when ruby-colored, amethyst. Uncrystallized silica also occurs in various conditions—agate, jasper, chal- cedony, onyx, etc. In all its forms it is converted into a silicate by fusion with sodium carbonate, and when lime, lead oxide or other metallic oxides are mixed with the sodium silicates, we get the various forms of glass. When a large excess of sodium carbonate is used, the glass is soluble in water, and is commonly known as soluble glass. The solution is sometimes called liquid silex. It is used as a cement, and in soaps. Silicic Acid, Orthosilicic Acid, H4Si04.—If sodium silicate be treated with hydrochloric acid, the following reaction occurs:— Na4Si04 4- 4HCI = 4NaCl 4- H4Si04. Solution of silicic acid is tasteless and feebly acrid to litmus. By evapora- tion it forms a gelatinous mass which can be brought to the composition H2Si03 (metasilicic acid), and by further heating gives the insoluble anhy- dride. Silicon combines with the halogens, forming bodies resembling the cor- responding carbon compounds. Silicon and fluorine have a strong affinity, forming silicon fluoride, SiF4. Silicon combines with positive elements, forming silicides, but many of these are of uncertain composition. Hydrogen silicide, H4Si, produced by the action of acids upon magnesium silicide, takes fire spontaneously. In its composition it is analogous to marsh gas, H4C. TIN. Tin, Sn, 118, occurs principally as dioxide, called tin-stone. It is white, soft and easily beaten into foil, but is not tough ; specific gravity, 7.28. It fuses at 4420 F. (2280 C), and resists very well the action of the air and of cold acids. Nitric acid forms an insoluble dioxide. Tin forms several valu- able alloys—pewter, gun-metal, type-metal, bronze and solder, elsewhere described. Speculum metal, used for metal mirrors, is an alloy of copper and tin: glass mirrors are coated with an amalgam of tin." Tin plate is iron coated with tin by dipping it into a bath of the melted metal. Two series of salts are known—stannous, unsaturated, and stannic, saturated. PLATINUM. 93 Stannous Oxide, SnO, is a feeble base. Stannous Chloride, SnCl2, is formed by dissolving tin in hydrochloric acid. Stannous chloride is used as a reducing agent. When mixed with mercuric chloride, mercury is set free and stannic chloride formed:— HgCl2 4- SnCl2 = Hg 4- SnCl4. Stannous chloride is used by the dyer as a mordant, under the name of tin crystals. Stannic Oxide, Sn02, Stannic Anhydride, is found as a mineral; also produced by burning tin in the air, by oxidizing it with nitric acid and by adding an alkali to stannic chloride. It unites with water in various pro- portions to form acids, and these form salts called stannates and metastan- nates. Stannic Chloride, SnCl4, Tin Tetrachloride, Libavius' Fuming Liquor.— This body is largely used by dyers under the name of nitro-muriate of tin. It is a colorless fuming liquid, boiling at 239.50 F. (115.30 C). Stannic Sulphide, SnS2, Mosaic Gold, is a bronze-colored powder used in printing and coloring. PLATINUM. Platinum, Pt, 197.1, occurs native, also alloyed with gold and silver and other elements. Platinum is hard, white and very heavy; specific gravity, 21.5; it fuses only at a very high temperature. It resists perfectly the action of the air and of most chemical agents, and for this reason is largely used in chemical operations. It dissolves in hot aqua regia, forming platinum tetrachloride, PtCl4. Platinum forms two series of compounds; its oxides are only feebly basic. Platinum Tetrachloride, or Platinic Chloride, PtCl4, is a red or brown deliquescent mass. It forms yellow insoluble precipitates with potassium and ammonium salts, but not with those of sodium, and is of great use in analysis for the separation of potassium and sodium. The remaining elements are rare and have as yet few applications of moment. Their names, symbols, accepted atomic weights and valencies will be found in the table of elements. Great scientific interest attaches to 94 INORGANIC CHEMISTRY. some of them, and in a few cases their compounds are used in special tests. Molybdenum in the form of ammonium molybdate (NH4)2Mo04 is used as a test for phosphoric acid. A compound of osmium, Os04 is used in microscopy. Osmium itself can be obtained in a crystalline form with a specific gravity of 22.48, being the heaviest substance known. Crookes has recently shown that the body heretofore known as yttrium includes five or more different elements, or, at least, different molecular groupings; other of the rarer elements show the same condition. Some of the rare elements exist widely diffused in minute amounts. ORGANIC CHEMISTRY. NATURE OF ORGANIC BODIES. Organic Chemistry is primarily the study of the substances which form part of the tissues of plants and animals. These are very numerous, and by various influences, such as action of heat or of oxygen, new bodies may be formed, and these are also included in organic chemistry. At the outset we must carefully distinguish between an organized and an organic body. The former has a definite structure, generally cellular, and is formed under the specific action of vitality. Organic bodies, on the other hand, may or may not possess structure. All organized bodies are organic, but all organic bodies are not organized. For the recognition of the organic nature of any substance the action of heat usually suffices. It causes decomposition, with evolution of smoky, strong-smelling vapors ; a residue of carbon remains which can be burned off by heating strongly in the air. The presence of nitrogen is usually indicated by a disagreeable odor like that of burning wool. Amine, NH3, is often formed and can be detected by appropriate tests. Organized bodies are in general easily recognized by the microscope. Carbon, hydrogen, nitrogen and oxygen are by far the most frequent elements which enter into the formation of organic bodies. During the last twenty-five years many artificial bodies have been formed, into which mercury, bismuth, arsenic, chlorine and iodine have been introduced; these, although analogous to natural organic bodies, are not capable of forming part of healthy tissue. Carbon is present in almost all organic bodies, and for this reason organic chemistry has sometimes been called the " chemistry of the carbon compounds." Hydrogen is also almost always present; oxygen somewhat less frequently; nitrogen still less frequently; while sulphur, phosphorus and iron are rather exceptional in their occur- rence. The following table gives a list of bodies belonging to different classes in organic chemistry, and shows how many changes may be made in the combinations of these few elements. The compounds all occur ready formed in nature:— 95 96 ORGANIC CHEMISTRY. C10H16..........Oil of turpentine. Ci2H22°n.......Cane sugar. C10H14N2.......Nicotine (from tobacco). C17H19N03.......Morphine (from opium). C2HrNS03.......Taurin (from bile). C3H9P06........Phospho-glyceric acid (from brain). C32H32FeN406.....Haematin (from blood). Proximate and Ultimate Composition.—The tissues of plants and animals, or the products of their decomposition, are generally mixtures of several independent substances. Butter is a mixture of four or five fats; common rosin contains two or sometimes three distinct bodies; opium and Peruvian bark are still more complicated, and brain and muscle structures are so complicated that as yet complete analyses have not been made of them. The substances which thus exist naturally in a state of mixture are called proximate principles, the separation and identification of them is called proximate analysis, and such of them as give characteristic qualities to the articles in which they occur are generally called active or essential principles; atropine, for instance, is the active principle of belladonna, for although many different bodies are contained in the belladonna leaf, atro- pine is the one upon which its physiological activity mainly depends. The ultimate principles of a substance are the elements (carbon, hydrogen, etc.) which it contains. Ultimate analysis, that is, the determination of the proportions of the elements that may be present, although requiring care in manipulation, is practically the same for all organic compounds. Transformation of Organic Bodies.—In addition to the bodies found ready-formed in plants and animals, many derivative substances are known. These are produced by a great variety of methods, some of which are of general application. [a) Action of Heat.—The great majority of organic compounds are changed by heat, some only slightly, others completely. Many are con- verted into new bodies, which escape in the condition of vapors, and may be subsequently condensed. In this way coal, when heated, gives rise to coal gas, coal tar, pitch, etc., these products being mixtures of many proxi- mate principles. Such a process is called destructive distillation. [b) Action of Oxygen.—At high temperatures most organic bodies burn, producing carbon dioxide and water. At low temperatures the oxy- gen may enter slowly into combination, or, as frequently happens, may NATURE OF ORGANIC BODIES. 97 substitute the hydrogen, the substitution taking place in the proportion of one atom of oxygen for every two atoms of hydrogen removed. In both these actions the resulting bodies are generally acids. [c) Action of Nitric Acid.—This varies with the temperature and degree of concentration of the acid. When very strong and cold acid is used, the action is generally a substitution of the molecule NO., for H, giv- ing rise to a series of bodies called nitro-compounds. When the acid is weak or hot, the action is usually the direct addition of oxygen, according to methods given in the preceding paragraph. [d) Action of Chlorine.—Chlorine sometimes enters into direct combination, but usually displaces the hydrogen and takes its place, atom for atom. Bromine and iodine act in the same manner. The substituting actions of oxygen, nitric acid, chlorine, etc., give rise to a very important series of compounds, which are more completely explained below. [e) Action of Dehydrating Agents.—These are bodies—sulphuric acid, and phosphoric anhydride, for examples—which have a high affinity for water. They act by abstracting hydrogen and oxygen in the proportion of two atoms of H to one of O. (/) So-called Natural Changes.—These are Fermentation, Putre- faction and Decay. Fermentation is a process by which certain organic bodies, particularly forms of sugar, are converted into new substances simpler in composition. The change is dependent on the development of minute living organisms, and the products differ with the nature of the organism. The conditions necessary to the action are: [a) Proper food, especially the ammonium salts and phosphates. These are generally present in the liquid about to be fermented, [b) A temperature from 6o° to ioo0 F. (200 to 400 C). Very strong solutions of sugar will not ferment. Many substances, especially those which coagulate albumin, have the power to stop fermentation, and are called anti-zymotics. Among these are boric acid, zinc chloride, mercuric chloride, phenol, alcohol, sulphites, many hydrocarbons, etc. Some important forms of fermentation are— 1. The Vinous, producing chiefly Alcohol C2H60 and Carbonic Anhy- dride, C02. 2. The Acetous, producing chiefly Acetic Acid, C2H402. 3. " Lactic, " " Lactic Acid, C3H603. 98 organic chemistry. 4. The Butyric, producing chiefly Butyric Acid, C4H802. Each variety of fermentation is dependent upon and caused by special forms of microorganisms. Putrefaction is a change which bodies containing nitrogen, especially organized bodies, undergo when exposed to air. They are usually con- verted into simpler products, some of which have characteristic and offen- sive odors, due in part to the sulphur and phosphorus sometimes present in organized tissues. Putrefaction is caused by the development of various forms of microorganisms. Substances which prevent this development will prevent the putrefaction, and are called antiseptics. Decay.—This is the decomposition of organic bodies by the slow action of oxygen. It takes place too slowly for any increase of temperature to be noticed, and it is rarely complete, that is, some portions of the elements escape action. When wood burns with a flame it leaves nothing but the incombustible mineral matter or ash, but when it decays a brown powder is left, which contains some of the original carbon and hydrogen. Decay requires the access of air, the presence of moisture and a temperature above the freezing point. Organic Substitution.—This is a process by which one or more atoms of a body are removed and their place occupied by an equivalent number of .atoms of some other element. The atoms replace one another strictly according to valency. Numerous substitution compounds are described further on; it will be sufficient here to outline the general principles of their formation. 1. Substitution by Oxygen.—Oxygen substitutes hydrogen, one atom replacing two of hydrogen; at least two atoms of oxygen are required, one to combine with the liberated hydrogen and the other to take its place. Thus alcohol, when exposed to oxidation, gives the following reaction:— Alcohol. Acetic Acid. C2H60 4- 02 = C2H402 4- H20. The bodies produced by oxygen substitution are usually acids. 2. Substitution by Chlorine.—Chlorine usually substitutes hydrogen; one atom of chlorine takes the place of one atom of hydrogen, but the hydro- gen thus set free combines with an atom of chlorine; so for the complete reaction two atoms of the latter are needed. Thus :— CH4 4- Cl2 = CH3C1 + HCl. nature of organic bodies. 99 If further substitution occurs it will be similar:— CH3C1 +'C12 = CH2C12 4- HCl. These reactions are generally obtained by the direct action of chlorine on the organic body. Proceeding in this way with the above case we finally reach complete removal of the hydrogen and the formation of CC14. This method of substitution is almost the only means we have of forming compounds between carbon and chlorine. Bromine and iodine follow substantially the same law, but do not act so readily. By the action of phosphoric chloride, hydroxyl is frequently substituted by chlorine. 3. Substitution by Sulphur.—Sulphur substitutes oxygen, atom for atom, but only a comparatively small number of such substitution compounds are as yet known. They are usually of very marked odor. As an example of a sulphur substitution we have C2H6S, which corresponds to alcohol C2H60. 4. Substitution by NOY—This is a substitution for hydrogen, and is the result of the action of strong nitric acid. Each molecule of N02 replaces one atom of H. The bodies thus formed are called nitro-compounds, the prefixes bi-, tri-, etc., being used to indicate the presence of two or more molecules of N02. The action of nitric acid on benzene results in the formation of nitro-benzene:— C6H8 4- HN03 4- C6H6N02 + H20. 5. Substitution by HS03.—Many organic bodies, especially those con- taining only hydrogen and carbon, when treated with sulphuric acid, form substitution compounds, called sulphonic acids, in which the molecule, HS03, takes the place of hydrogen in the organic body. Benzene, for instance, gives— C6H6 4- H2S04 = C6H5HS03 4- H20. Benzene-Sulphonic Acid. The C6HB replaces the hydroxyl of the acid, not the hydrogen. Other Substitutions.—Nitrogen may, under certain circumstances, be substituted for hydrogen. The bodies so formed are called azo-compounds. Silicon may replace carbon, but only a few such instances have been observed. Organic Synthesis.—Until Wohler prepared urea by heating ammo- nium cyanate, it was supposed to be impossible to prepare artificially any 100 organic chemistry. one of the constituents of animal or vegetable secretions. Within twenty- five years past great advances have been made in the work of producing organic bodies artificially, either directly from mineral substances, or from other organic bodies. These methods are called organic synthesis, and throw much light on the molecular structure of the bodies concerned. Formates, which occur in natural secretions, may be prepared from potassium formate, which may be made artificially by the action of carbon monoxide on potassium hydroxide:— KHO 4- CO = KCH02. Empirical and Rational Formulae.—When symbols are written so as to express merely the number of atoms of each element, without attempt- ing to show the arrangement or the relations of them, we have what are called empirical formula. When, in addition to expressing the composi- tion, we endeavor, by the arrangement of the symbols, to express the manner in which the molecules are formed and the relation it has to other bodies, we have rational formula. Thus, alcohol may be represented empirically as C2H60, but many of the changes which alcohol undergoes indicate that one of its atoms of hydrogen is closely associated with the oxygen, while the other hydrogen atoms are more closely associated with the carbon. Accordingly, the formula, C2H5H0 is used to indicate this arrangement. A perfect rational formula should indicate how the body is formed and all the changes to which it tends, but such formulae are not yet possible to us. In a large number of organic compounds the rational formulae are not known. Percentage Composition.—The results of analysis may be expressed without any reference to symbols, or to the number of atoms of the elements present. We may give simply the number of parts by weight of each element contained in one hundred parts of the body. Thus, the composi- tion of ordinary sugar may be stated as:— Carbon...................42.11 Hydrogen................. . 6.43 Oxygen...................51.46 100.00 These figures represent the percentage composition. (See page 34.) Isomerism, Metamerism and Polymerism.—Many instances are known, of two or more bodies entirely different in origin and character nature of organic bodies. 101 having the same percentage composition. Acetic acid, lactic acid and glu- cose all have the composition :— Carbon...................40 Hydrogen.................. 6.66 Oxygen...................53.34 100.00 Similarly, the bodies known respectively as methyl acetate, ethyl formate and propionic acid have the same composition. This relation is known as isomerism, and if we compare the formulae of isomeric bodies they fall naturally into two classes, 1st, those that agree both in number of atoms and molecular weight; 2d, those that differ in number of atoms and molecular weight. The compounds methyl acetate, ethyl formate and propionic acid form a series of the first class, while acetic acid, lactic acid and glucose are examples of the second :— Empirical Rational Mol. Formula. Formula. Wt. Methyl acetate..........C3H602 CH3C2H302 74 Ethyl formate.......... 03H6O2 C2H5CH02 74 Propionic acid..........C3H602 C2H5C00H 74 It will be seen that the rational formulae are different, but as far as actual number of atoms is concerned each body is identical. Such a relation is said to be one of metameric isomerism or metamerism. In the other case referred to we have:— Empirical Rational Mol. Formulce. Formulas. Wt. Acetic acid........... C2H402 HC2H302 60 Lactic acid...........C3H603 HC3H503 90 Glucose ............06H1206 Unknown 180 Here the only agreement is in percentage composition. Such a relation is called polymeric isomerism. Isomeric Modification.—A special form of isomerism is where two or more bodies are identical in composition and molecular weight, and so nearly alike in properties and reactions as to indicate that they are forms of the same body, but each is under a slight modification. Thus five modifi- cations of the substance called pentyl alcohol (C5H120) have been described. Each one of these differs slightly from the others in boiling point, action on light, etc., but they are all entitled to the name pentyl alcohol. 102 ORGANIC chemistry. These are more intimate relations than ordinary isomerism, and can best be explained by supposing that certain minor differences exist in the mole- cule, particularly with reference to the position of the carbon atoms. Determination of the Formulae of Organic Bodies.—The per- centage composition of a body gives only an imperfect clue to its formula; to obtain this latter we must know something of the molecular weight. Now, as a general rule, it is found that the molecular weight is equal to twice the density of the body in state of vapor compared to hydrogen. The determination of the vapor density becomes, therefore, an important operation. The use of these determinations of vapor density is shown by the following example. The composition of alcohol might be represented by the formulae C2H60, C4H1202, or any other multiple, because the pro- portion between the elements would remain the same. The vapor density is, however, found to be 23, and since, by the rule above given, the vapor density is half the molecular weight, such a formula must be chosen as shall give a molecular weight of 46. The one which will give this is :__ c2 = 24 H6 = 6 O = 16 46 C2H60 is, therefore, the Correct formula for alcohol. The reason for this is shown by the following calculations :__ The molecule of hydrogen is H2 and weighs.....2 " alcohol is C2H60 " .....46 The ratio, therefore, of weight of one molecule (or given volume) of alco- hoi, to a molecule (or given volume) of hydrogen is as 46 to 2 (23 to 1). Since in the determination of vapor density, the comparison is made to hydrogen as unity, the figure obtained by experiment must be doubled to be com- parable to the weight of a molecule of hydrogen. Homologous and Isologous Series.—In many cases when the formulae of organic bodies, similar in some properties, are arranged in order, they will be found to differ by a regular rate, the carbon increasing or diminishing by one atom and the hydrogen by two. The result is a series of bodies differing by CH2. Such a series is called a homologous series. When the carbon remains the same, but the hydrogen differs by H , the series is said to be isologous. NATURE OF ORGANIC BODIES. 103 In the following examples each vertical column represents a homologous, each horizontal line an isologous series:— CH4 CH2 c C2H6 C2H4 C2H2 C3H8 C3H6 C3H4 C4H10 C4H3 C4H6 C5H12 C5H10 C5H8 General Formulae.—The existence of these homologous series, as above described, renders it possible to express by a single formula the composition of any member of the group. Thus, in the first series, the atoms of hydro- gen are always two more than twice the carbon atoms; in its next series the atoms of hydrogen are just twice the carbon; in the third series the hydro- gen atoms are'two less than twice the carbon atoms. For the first series we could give, then, the general formula Cn H2„ 4- 2; n represents any num- ber of atoms. From this formula we can derive any member of the series; for instance, let it be required to write the formula of the sixth member. As the carbon increases regularly one atom at a time, the sixth member will have six carbons, therefore C6. Twice six plus two is fourteen; the formula is therefore C6H14. The general formula of the second series above given is CUH2D; of the third series CnH2n_2. Carbon Chains.—The valency or combining capacity of each member i of a homologous series is the same. It is not difficult to understand how this is, as far as regards the first member of the series, but at first sight it would seem as if each member should have a different valency. Thus, if CH4 is a saturated molecule, C2H6, a homologue with it, would seem to be be a dyad; for carbon being a tetrad, two of carbon would have a capacity of eight; six would be saturated by the H6, leaving two unsatisfied. Experiment, however, shows that C2H6 is not a dyad, but a saturated molecule, and so with all bodies homologous with it. The explanation of this fact is upon the supposition that, in forming the molecules, the carbon has in part satisfied itself, so that each atom of carbon added carries into the molecule only two degrees of valency, which the H2, added at the same time, immediately satisfies. This explanation cannot be made clear without the use of diagrammatic formulae. Thus the first member of the series H would be H—C—H; the second member would have the carbon partly I H 104 ORGANIC CHEMISTRY. H H satisfying itself, thus: H—C—C—H, the molecule then being saturated. H H H H H The third would be H—C—C—C—H, and so on with each member. We I I I H H H might give names to the linked carbon atoms—or carbon skeletons, as they have been ingeniously called—calling them di-carbon, tri-carbon, etc. In addition to the arrangement known as open chains, carbon atoms are sometimes arranged in closed chains. For illustration of these forms see benzene. Properties of Bodies in Homologous Series.—The relation of homologous bodies is not a mere accidental relation in formulae. By com- paring different members of the same series we can always see similarities either in origin, general properties or chemical relation. The series begin- ning with CH4 is characterized by general indifference to chemical action. The hydroxides of the series beginning with CH3 constitute a series of alcohols which possesses specific physiological action. In each series the fusing and boiling points, specific gravity, density of vapor, increase with considerable regularity. The molecular weight, of course, increases, but in the series beginning with CH2 the percentage composition is the same in all, and they are, therefore, instances of polymeric isomerism. The molecu- lar weight increases regularly, 14,28,42, etc., but the percentage composition is always carbon, 85.71; hydrogen, 14.29. By the density of the vapor we can distinguish each one and determine the formula. Isomeric Modification in Homologous Series.—It has been pointed out, on a previous page, that many organic bodies occur in two or more forms which are not sufficiently distinct to permit us to consider the bodies as different, and yet they are evidently not exactly identical. In such cases the diagrammatic method of showing the linking of the carbon atoms may be utilized to show that the difference of properties in two or more forms of the same body may be due to different positions of the carbon atoms, with respect to each other and to the other elements present. In the lower mem- bers of the series, on account of the small number of atoms present, it is generally impossible to make more than one arrangement; but in the higher members several different arrangements are possible, and each arrangement NATURE OF ORGANIC BODIES. 105 will have certain characteristic indications, either in the chemical or physi- cal properties of the bodies formed. In the series beginning with CH4 no variation of arrangement can be made in the carbon atoms in the first three members, but in the fourth member tetrane, C4H10, we may have no carbon atom united to more than two other carbon atoms, or we may have one carbon to three other carbon atoms:— First Form. Second Form. H H H H H H H H—C—A—C—C—H H---C—C—C---H I I I I II H H H H H H H—C—H or CH3CH2CH2CH3 | H or CH3CH(CH3)CH3 In the second compound, the CH3, which stands rather apart from the remainder of the molecule, may be regarded as a substituting molecule; and the number of isomeric modifications of which any body is susceptible will depend on the number of points at which the substitution can take place. We might formulate the two forms of tetrane very simply thus:— C4H10, ordinary tetrane. C3H7(CH3), methyl tritane. The distinction between such isomeric modifications may often be obtained by determining the substances produced, when the different bodies are subjected to the same decomposing influences. Classification of Organic Bodies.—No system of classification of organic chemistry is entirely satisfactory. The following will suffice for this work: Hydrocarbons (bodies containing C and H). Derivatives from the hydrocarbons. Fatty series (open carbon chains): Alcohols, ethers, aldehydes, acids, sugars and starches, oils and fats. Aromatic series : Benzene and derivatives (closed carbon chains). Compounds containing nitrogen. Cyanogen derivatives, ammonium derivatives, alkaloids, azo-com- pounds. 8 106 ORGANIC CHEMISTRY. HYDROCARBONS. The compounds of carbon and hydrogen are very numerous. Carbon being a tetrad, the highest quantity of hydrogen which can combine with carbon is four atoms. In the compound CH4 we have the type of the hydrocarbons; all other compounds of this class may be regarded as de- rived by subtraction or substitution, or both. If we substitute for all or part of the hydrogen in CH4 its equivalent of any other substance, we will not disturb the chemical nature; it was a satu- rated hydrocarbon, and remains so. Hence CC14 will be referable to the same group as CH4. By successive subtractions of H from CH4 we may obtain a series of radicles, the valency of which will be equal to the num- ber of hydrogen atoms removed. CH3 lacks one atom of H; it is a monad radicle; CH2 is a dyad, CH a triad, while C, of course, is a tetrad. From each of the intermediate molecules—hydrocarbon radicles they are called— derivatives may be obtained, comparable in the main to the derivatives which the elements themselves yield. Thus, CH3 may yield a chloride, bromide, hydroxide, sulphate, etc., analogous in formulae to the same com- pounds formed by the elements of the potassium group. From CH2 com- pounds may be obtained analogous in formulae to those from dyad metals, and so on. In addition, these radicles have substitution power, that is, they may replace the hydrogen of other organic compounds. Each of these radicles and each of their derivatives may constitute the first member of a homologous series. A system of nomenclature by terminations has been adopted to distinguish the different series; the vowels are used in regular order, and the syllable yl indicates uneven valency. The number of carbon atoms is indicated, except in the first two members, by syllables formed from the Greek numerals. It does not necessarily follow that all these bodies have been obtained, but most of them are known, and the others could doubtless be pre- pared. The members of each vertical column are homologous with each other. The members of the first series being saturated hydrocarbons, are prac- tically indifferent to chemical agents. Common paraffin is one of them, and the series has, for this reason, been called the paraffins; the members of the third series have been called the olefins, from the former name of one of the members of it. The following table will be sufficient to show the principle of the above classification:— PARAFFINS OR METHANE SERIES. 107 Series. Series. Series. Series. Series. i 2 3 4 5 len. Formula Gen. Formula Gen. Formula Gen. Formula Gen. Formula ^nHm + 2. CnH2n + i. CnH2n. CnH2n — r. CnH2n — 2. Valency. Valency. Valency. Valency. Valency. 0 I II in IV Methane. Methyl. Methene. Methenyl. Methine. CH4 CH3 CH2 CH C Ethane. Ethyl. Ethene. Ethenyl. Ethine. C2H6 C2H5 C2H4 C2H3 C2H2 Tritane. Trityl. Tritene. Tritenyl. Tritine. C3H8 C3H7 C3H6 C3H5 C3H4 Tetrane. Tetryl. Tetrene. Tetrenyl. Tetrine. C4H10 C4H9 C4H8 C4H7 C4H6 Pentane. Pentyl. Pentene. Pentenyl. Pentine. C5H12 C5H11 C5H10 C5H9 C?H8 Hexane. Hexyl. Hexene. Hexenyl. Hexine. C6H14 C6H13 C6H12 C6H11 C6H10 PARAFFINS OR METHANE SERIES. Saturated molecules not easily affected by chemical agents. Many of them are found in petroleum. Methane, Marsh Gas, CH4.—This is a colorless gas existing in common coal gas, being formed during the destructive distillation of coal. It is also produced by decay of vegetable matter, especially under water, and hence is frequently found in marshes, whence its name. By stirring the bottom of a marshy pool, bubbles of methane will escape. Common Paraffin exists in petroleum and in coal tar. It is a mixture of several of the higher members of the series. It is a white, waxy solid, easily fusible, soluble in ether, little acted on by acids or alkalies. It is used for a protecting coating in chemical apparatus, and as a substitute and sometimes as an adulterant for wax. Cosmoline, vaseline and similar substances are also in part soft paraffins. Derivatives of the Paraffins. These bodies are not very easily acted upon by chemical agents, but substitution compounds may be obtained by direct action of chlorine, and even bromine, upon all of them, and nitro-compounds may also be produced directly from some of the higher 108 ORGANIC CHEMISTRY. members. By successive substitution of the hydrogen in CH4 we get four bodies which may be given as an illustration of the nomenclature of this kind of compounds: — Methane....................CH4 Monochlorinated methane.............CH3C1 Di " " .............CH2C12 Tri » " .............CHC1, Carbon tetrachloride...............CC14 The third substitution is the very important body, Chloroform, CHC13. When pure it is a colorless, fragrant liquid, very volatile, specific gravity 1.48, not easy to burn, insoluble in water and much heavier than that liquid. It boils at 1420 F. (6l° C), has high solvent powers and is a valu- able anaesthetic. Iodoform, CHI3, is now much used as an antiseptic, especially in sur- gery. It cannot be obtained by direct substitution, but is easily made by the action of iodine on a mixture of alcohol and potassium hydrate. It forms bright yellow crystals. Carbon tetrachloride, CC14, is the final result of the substitution of chlorine for the hydrogen of methane, CH4. It is a colorless liquid of specific gravity 1.56, freezes at —90 F. (—230 C), and boils at 1720 F. (770 C). It is a powerful anaesthetic. METHYL SERIES. This is a series of monad radicles which are usually called the alcohol radicles because their hydroxides are the common alcohols. Derivatives from the Methyl Series. Normal oxides called ethers. (CH3)2q . . . Methyl ether, analogous to Na20, sodium oxide. (C2H5)20 . . Ethyl ether, " « « Compounds with halogens, sometimes called ethers. (CH3)C1 . . . Methyl chloride, analogous to NaCl, sodium chloride. (CsH^Cl . . Amyl Compounds derived from acids, called compound ethers or esters. (CH3)2S04 . Methyl sulphate, analogous to Na2S04, sodium sulphate. (C5H1JNO3 . Amyl nitrate, " NaN03, sodium nitrate. methyl series. 109 The compounds analogous to the acid salts are sometimes called vinic ACIDS. (C2Hs)HS04 . Sulphethylic acid, analogous to KHS04. (C5H11)HS04 Sulphamylic " Hydroxides, called ALCOHOLS. (C2H5)HO . . Ethyl alcohol, analogous to KHO. (CjHnJHO. . Amyl " Compounds containing two different radicles, called«MiXED ethers. (CH3)(C2H5)0 Methyl-ethyl ether. Chlorides, bromides, hydrides, etc., are known, and many substitution compounds. Each set of compounds here mentioned constitutes a homologous series. In general, when alcohols are oxidized by a limited amount of oxygen, two atoms of hydrogen are removed and no oxygen is added. When oxidized in a free supply of oxygen, an atom of oxygen takes the place of the removed hydrogen. The bodies produced in the first case are alde- hydes, in the second, acids. In this way we have— Ethyl Ethyl Alcohol. Aldehyde. (C2H5)HO 4- O = C2H40 4- H20. Acetic Acid. (C2H5)HO + 02 = C2H402 4- H20. Thus each alcohol may be made to yield an aldehyde and an acid, each of these forming one of a homologous series. The series of acids is very important; many of them exist in fats and oils, hence they have been called fat-acids. The following table gives a conspectus of some of the most important derivations of the methyl series of hydrocarbons. Of the hydrogen that remains in the acid one atom is replaceable by any positive element or radicle, so that we generally write it apart from the other atoms, as in HCH02, formic acid. In the table on the next page only a few examples of the compound ethers are given. Oxides, ethers. Hydroxides, alcohols. Aldehydes. Acids. EXAMPLES OF COMPOUND BTHEKS. Radicle. Acid sulphates. vinic acids. Sulphates. Nitrates. CH3 C2H5 C3H7 C4H9 C5H11 (CH3)20 (C2H6)20 (QH7)20 (C4H9)20 (C5Hn)20 CH3HO C2H5HO C3H7HO C4H9HO C5HnHO CH20 C2H40 C3H60 C4HgO C5H10O HCOOH CH3COOH C2H5COOH C3H7COOH C4H9COOH CH3HS04 C2H5HS04 C3H7HS04 C4H9HS04 C5HnHS04 (CII3)2904 (C2H5)2S04 (C3H7)2S04 (C4H9)2S04 (C5Hn)2S04 CH3N03 C2H5N03 C3H7N03 C4H9N03 C5HUNQ3 Isomeric modifications are possible in these bodies, except in the first two lines, i. e., methyl, ethyl and their derivatives. Methods of Forming the Compounds of the Methyl Series.—The starting point is generally the alcohols. The ethers, simple and compound, are produced by the action of acids on the alcohols. The aldehydes are produced by partial oxidation, the acids by complete oxidation; many of the acids exist ready formed in nature. The alcohols will be described first. They are often called the monatomic alcohols, because they contain a monatomic radicle. METHYL SERIES. Ill It has been pointed out on page 31 that the function of any oxygen acid is dependent upon the presence of hydroxyl, and that the basicity of such acid is equal to the number of hydroxyl groups present. In consequence of the feebly positive character of the hydrocarbon radicles, the function of any hydroxyl in an organic body will be influenced by the number and position of the negative atoms also present. Accordingly we find many organic hydroxides in which neither strongly acid nor strongly basic prop- erties can be recognized. Thus, common alcohol, C2H5H0, acts upon both sodium and sodium hydroxide to form the body NaC2H50, which is called sodium ethylate. In this, however, the alkalinity of the sodium hydroxide is not diminished. When acetic acid acts upon the same sub- stances, sodium acetate is formed, which is neutral. The difference between the relations of the hydroxyl in alcohol and acetic acid is shown by graphic formulae— H H HO II I II H—C—C—O—H H—C—C—O—H I I I H H H - Alcohol. Acetic Acid. Hydroxyl that is united to carbon which is in turn united to oxygen or other negative body, is known as acid hydroxyl. The molecule, CO, is known as carbonyl, and its combination with hydroxyl, COOH, is called carboxyl. No organic body can be properly called an acid unless it con- tains hydroxyl associated in this manner with a strongly negative radicle. It is especially carboxyl which is found in organic acids, and the number of carboxyl molecules determines the basicity of the acid. Hydroxyl that is connected directly to unoxidized carbon, that is, is not in the carboxyl or analogous condition, does not confer acid properties and is known as alcoholic hydroxyl. Methane may be taken as the type of all open chain compounds, these being represented as derived from it by substitution of the hydrogen by various elements or radicles. Eveiy substance so formed may be named in accordance with the substitutions that may be supposed to have occurred. Thus, by successive substitution of the radicle methyl we get a series of hydrocarbons homologous with methane. CH4..........Methane. CH3(CII3).......Methyl-methane (ethane). CH2(CH3)2.......Dimethyl-methane (tritane). CH(CH3)3.......Trimethyl-methane (tetrane). 112 ORGANIC CHEMISTRY. By substitution by hydroxyl we get the alcohols CH3(HO)..........Hydroxymethane. CH2(HO)2..........Dihydroxymethane. CH(HO)3..........Trihydroxymethane. By simultaneous substitution by a hydrocarbon radicle and hydroxyl we get alcohols homologous with the above. CH2(CH8)(HO) . . Hydroxymethyl-methane (hydroxyethane). CH(CH3)2(HO) . . Hydroxydimethyl-mefhane. CH(CH3)(HO)3 . . Methyldihydroxymethane. Simultaneous substitution of oxygen and hydroxyl may develop in con- nection with the carbon atom, the molecule COOH, carboxyl, and thus produce an acid. Substitution of the remaining hydrogen atom by methyl will produce a homologous acid. CH(HO)0......Oxyhydroxy-methane (formic acid). C(CH3)(HO)0 .... Oxyhydroxymethyl-methane (acetic acid). In the higher members of the series, the substitution may involve either the hydrogen of the methane or that of one of the substituting radicles. CH(CH3)3 .........Trimethyl-methane. CH(CH2CH3)(CH3)2.....Dimethyl-methylmethyl-methane. Numerous isomeric forms are therefore observed in the higher members of the series, depending on the position of the substituting radicles. METHYL SERIES. 113 CONSPECTUS OF MONATOMIC ALCOHOLS. Boiling Point. Systematic Common Sp. Gr. Source. Name. Name. approx. F. C. Methyl Wood spirit O.798 151 66.1 Distillation of wood. Ethyl Alcohol 0-793 173 78.3 Fermentation. Trityl Propyl alcohol O.82O 206 96.6 tc Tetryl Butyl " O.803 233 112 f( Pentyl Amyl " Fusel oil 0.8II 270 132 * Hexyl Caproic alcohol O.819 3°9 154 Heptyl OZnanthic " 343 173 Action of KHO on castor oil. Octyl O.87I 356 180 From parsnip oil. Nonyl 392 200 Decyl Rutic " 414 212 Oil of rue; fuses at 44-5° F. (7° C). Dodecyl Laurie " Whale oil; fuses at 75° F. (24° C). Tetrad ecyl Mvristic " • Hexadecyl Cetyl Spermaceti; fuses at 1220 F. (900 C). Octadecyl Stearic " Cerylic " Melissic " From stearic acid; fu-ses at 1380 F. (590 C). Chinese wax; fuses at 174° F. (78° C). Beeswax;, fuses at 1850 F. (85° C). Methyl alcohol, (CH3)HO, wood spirit, is usually made by distilling wood. The crude material is difficult to purify. True methyl alcohol is colorless, and of pleasant odor. It boils at 1520 F. (66. 5°C), and its effects on the animal system appear to be less severe and more transient than those of common alcohol. Methylated spirit is a mixture of 90 parts common alcohol with ten parts methyl alcohol. Ethyl alcohol, (C2H5)HO, common alcohol, spirit of wine, is produced in the vinous fermentation of sugar, alcohol and carbonic anhydride being chiefly formed; it can also be prepared artificially. On the large scale the sprouted grain called malt is generally used. The general nature of the 114 ORGANIC CHEMISTRY. fermentation is explained in connection with the sugars. The fermented spirit is concentrated by distillation, but the strongest thus prepared contains about five per cent, of water. To withdraw all the water, it is necessary to distill with quicklime or calcium chloride, by which absolute alcohol is formed. This is inflammable, absorbs water and mixes with it in all pro- portions. Proof-spirit contains 50.8 parts by weight of absolute alcohol to 49.2 of water, and has a specific gravity of 0.920. Commercial alcohol is a color- less volatile liquid, of which the properties, effects and uses are well known. It boils at about 1800 F. (8l° C). Alcohol is contained in wine, beer and spirits; certain essential oils, sugars, or extracts being employed as flavor- ing agents. Whisky, brandy, and other spirits contain from 40 to 50 per cent, of alcohol; wines, from 17 (port and Madeira) to 7 or 8 (hock and light clarets) per cent.; porter and strong ale contain from 6 to 8 per cent., lager beer about 5 per cent.; the mild fermented liquors known as mead, root beer, spruce beer, contain from j£ to I per cent. The effervescence of fermented liquids is due to the carbon dioxide which is produced with alcohol, thus:— Glucose. Alcohol. C6H1208 breaks up into 2C2H,0 + 2C02. The carbon dioxide is retained by bottling the liquid before the fermen- tation is over. Pentyl Alcohol, Fusel Oil, (C5Hu)HO.—The radicle C5HU has been called amyl, and this alcohol is generally known as amyl alcohol. It is a by-product in fermentation, and is found in raw spirits and new liquors. When pure, it is a colorless, oily liquid, with a peculiar odor, a hot and acrid taste, and decidedly poisonous action. The alcohols derived from the higher radicles are mostly wax-like. Isomeric Forms of Alcohol.—Methyl and ethyl alcohols present only one form, but a number of isomers of the higher alcohol have been obtained. Comparison of these isomers has led to their division, according to a sup- posed arrangement of the carbon atoms, into three groups, primary, second- ary and tertiary alcohols. Primary alcohols contain the group CH2OH joined to one alcohol radicle; secondary alcohols contain the group CHOH joined to two radicles, and tertiary alcohol contains the group COH, joined to three radicles. ETHERS. 115 The graphic formulae show this principle best. H H H H I I I I H -O—C—C—C—C—H I I I I H H H H H H—O—C- H H I I -C—C—H I I H H Primary Tetryl Alcohol. (C3H,)CH2OH. H—C—H I H Secondary Tetryl Alcohol. (CH3)(C2H5)CHOH. H I H—C—H H I H—O—C—C—H I H H—C—H Tertiary Tetryl Alcohol. (CH3)3COH. ETHERS. The primary alcohols, by the action of bodies which have an affinity for water (sulphuric and phosphoric acids), are converted into oxides, called ethers. If free acids are present when the ether is being formed, the two bodies will generally act on one another, producing a compound ether, which is merely the replacement of the hydrogen of the acid by one or more molecules of the radicle. The only simple ether of any importance is— Ethyl oxide, (C2H5)20, common ether, often wrongly called sulphuric ether, usually made by the action of sulphuric acid upon alcohol. Acid ethylsulphate is first formed and then decomposed :— Alcohol. Acid Ethylsulphate (C2H6)HO + H2S04= (C2H6)HS04 + H20. 116 ORGANIC CHEMISTRY. Another molecule of alcohol is then acted upon, thus:— Ether. (C2H5)HO + (C2H5)HS04 = H2S04 + (C2H5)20. Ether is a colorless, very volatile liquid, of distinct odor, boiling at 980 F. (370 C). Specific gravity 0.723. Its vapor is inflammable and very heavy. It is a solvent for fats, fixed and volatile oils, resins and many other proxi- mate principles. Its anaesthetic uses are well known. Compound Ethers.—Many of these have marked odor and are the flavoring materials of flowers and fruits. They can mostly be made artifi- cially, and various mixtures of them are extensively used for imitating flavors. Ethyl bromide, C2H5Br, is an anaesthetic. Ethyl nitrite, C2H5N02, is one of the ingredients of the old remedy known as sweet spirit of nitre. Pentyl nitrite, C&H11N02, often called amyl nitrite, is made by the action of nitric acid upon pentyl (amyl) alcohol. It is a yellowish liquid, of well-marked odor, boiling at 2050 F. (960 C). By the action of potassium or sodium upon alcohols, bodies having some of the properties of caustic alkalies are obtained. Thus, with sodium and common alcohol, the reaction is:— C2H5HO + Na = C2H5Na0 + H. C2H5NaO is called sodium ethylate; it is a caustic liquid, which has been employed as an escharotic. SULPHUR ALCOHOLS, MERCAPTANS.—The oxygen of organic bodies, as of inorganic bodies, may be replaced by any other ele- ment of the oxygen group. Ethyl alcohol, for instance, has a corresponding sulphur compound, C2H5HS, called mercaptan; its proper name is ethyl hydrosulphide. Corresponding ethers also are known; thus, (C2H5)2S, ethyl sulphide. These sulphur derivatives are mostly strong-smelling and irritating compounds. A few of them exist ready-formed in the secretions of animals and plants. The essential.oils of mustard and garlic are sulphur compounds, and are noticed elsewhere. ALDEHYDES.—These are the results of the removal of two atoms of hydrogen from the alcohols, and stand intermediate between these and the acid. Ethyl aldehyde, often called acetic aldehyde, or simply aldehyde, C2H40, is often present in liquors, especially in raw forms of commercial KETONES. 117 spirits, and probably gives to such articles some of their injurious qualities. It is a colorless, volatile liquid, lighter than water, and boiling at 700 F. (210 C), having a powerful affinity for oxygen, and therefore a reducing action. It presents several isomeric modifications, one of which, paralde- hyde—to which the formula C6H1203 has been assigned—has decidedly narcotic properties, and has been used as a substitute for morphine, etc. All the aldehydes of the series form numerous complicated compounds of great chemical interest, but as yet of little practical value. The structural formula of common aldehyde is— H O I H H—C—C—H I H It will be noted that no hydroxyl is present, and hence aldehyde has neither acid nor basic properties. Chloral.—By substituting three atoms of hydrogen in aldehyde, by chlorine, we obtain a colorless liquid heavier than water (specific gravity 1.18), and boiling at 2010 F. (940 C). This is chloral, C2HC130. It combines with one molecule of water to form a crystalline, pungently smell- ing solid, soluble in water, which is now used under the name of chloral hydrate. It was originally suggested as a hypnotic, on account of the decomposition which it undergoes in alkaline solutions, as shown in the following reaction: — Sodium Sodium Chloral. Hydroxide. Formate. Chloroform. C2HC130 + NaHO = NaCHO, -f CHC13. KETONES.—By the destructive distillation of calcium acetate, a body called acetone, C3H60, is formed, differing from aldehyde, C2H40, by CH2. Acetone is the type of a group known as the ketones, which are products of the various reactions, for instance, of destructive distillation. They contain carbonyl, CO, united to two monad radicles. Common acetone, for instance, is a dimethyl ketone— CH3X )CO CH,' 118 ORGANIC CHEMISTRY. FAT-ACIDS. This term, applicable strictly to only a few of the series, will suffice to distinguish the homologous bodies derived from the alcohols by substitu- tion of two atoms of hydrogen by one atom of oxygen. They form an extensive and important class; nearly all of them are natural products. The fixed oils and fats contain some of the higher members of the series. Some have been produced artificially by a reaction, of which the following is a tjpe:— Ethyl Alcohol. Acetic Acid. C2H60 + 02 = C2H402 4- H20. Each of the acids so produced contains one carboxyl group, the hydrogen of which can be replaced by a positive element or radicle, and it is usual to designate this fact by writing the formula with the carboxyl separated from the others, as shown in the following cases. The lower members of the series are freely soluble and miscible with water, strongly acid and irritating, but as the quantity of carbon and hydrogen increases, the com- pounds become more and more oily, and the higher members are distinctly fatty, feebly acid, insoluble in water, but soluble in alcohol and ether. Formic Acid, HCOOH, originally prepared from the red ant (Formica rufa), can be made by a number of methods. Formic acid is a powerful reducing agent, blisters the skin, and has nearly the same boiling and freezing point as water. Acetic Acid, CH3COOH.—This occurs in small quantities in animal and plant juices. In the dilute form it constitutes vinegar, which contains from 3 to 6 per cent, of the acid, and is usually made by oxidizing dilute alcohol in the presence of a ferment. Acetic acid is also produced in the distillation of wood, being in this case generally contaminated with tar and called pyroligneous acid. When pure, it is a colorless, corrosive liquid, solidifying at 62.60 F. (170 C), and boiling at 246° F. (1190 C). This is glacial acetic acid. The dilute forms are less active, and in vinegar its effects are quite mild. Acetates.—The most important of these are :— Sodium acetate, NaC2H302, which forms deliquescent crystals, con- taining 3H20. Ammonium acetate, (NH4)C2H302, is used in medicine in the form of a solution in water called spirit of Mindererus. HOMOLOGOUS SERIES OF FAT-ACIDS. Empirical Formula. Melting Point. Boiling Point. Common name. Properties. Natural Occurrence. F. c. F. c. Formic .... CH202 34 I 212 100 Colorless volatile liquid. In red ants and some other insects, and in some stinging plants. Acetic .... C2H402 62 17 246 119 Colorless pungent liquid. Slow oxidation ofalcohol and sugar Propionic . . . C3H602 62 17 256 141 Crystalline solid. Butyric .... C4H802 — 4 — 20 322 161 Colorless liquid of disagreeable odor. Butter and other animalsecretions. Valeric .... C5H10O2 347 175 Colorless liquid of disagreeable odor. Valerian root. Caproic .... CEnanthylic . . C6H1202 C7H1402 4i 5 388 414 198 212 Colorless oily body. Slightly soluble in water; has an agreeable odor. Butter and coco-nut oil. Oxidation of castor oil. Caprylic . . . Pelargonic . . C8H1602 C9Hi802 57 64 18 456 500 236 260 Crystalline solid. Butter, coco-nut and castor oils. Geranium leaves. Capric .... ClOH2o02 86 3° 505 270 Crystalline mass having the odor of sweat. Butter and coco-nut oil. Fusel oil. Laurie .... Q1H22O2 no 44 Silky crystals. In coco-nut oil. Myristic . . . Ci4H2802 129 54 Crystalline scales. In nutmeg and coco nut oil. Palmitic .... Ci6H3202 M3 62 Fat-like solid. Most natural fats. Margaric . . . ^-17H3402 140 60 « Resembles palmitic. Stearic .... CibHsjO;; 156 69 " " Most natural fats. Arachidic . . . C2oH4o02 167 75 White, crystalline, fatty solid. Peanut oil. Behenic .... C22H4402 168 76 " " " Oil of ben. Hyanic .... ^2sH5o02 171 77 Resembles Cerotic. Cerotic .... ^27^6402 172 78 Crystallizes in small grains. Free in beeswax. Melissic .... C30H60O2 190 88 Derived from beeswax. 120 ORGANIC CHEMISTRY. Lead acetate, Pb(C2H302)2, sugar of lead, made by dissolving lead monoxide in acetic acid, forms white crystals, soluble in water. By boiling this solution with lead monoxide, a considerable amount of the latter is dissolved, and the sub-acetate, more correctly oxy-acetate, is formed, called Goulard's extract, and when much diluted, lead water. Copper acetate, Cu(C2H302)2, is not important; but an irregular and variable compound of it with copper hydroxide, known as verdigris, is made by exposing alternate layers of sheet copper and refuse grape skins to the air; ethyl alcohol is formed and then converted into acetic acid which acts on the copper. Ferric acetate, Fe2(C2H302)6, is used in medicine. Ferrous acetate, Fe(C2H302)2.—An impure form, obtained by dissolving iron in crude acetic acid; is used in dyeing. Aluminum acetate, A12(C2H302)6, is used in dyeing and calico printing. Butyric (Tetrylic) Acid, C3H7COOH.—This may be obtained from butter-fat, and from some fruit flavors, and also by fermentation of sugar with cheese and chalk. It is a colorless liquid having the disagreeable odor of rancid butter. Valeric (Pentylic) Acid, C4H9COOH, is found in valerian root and in other plants. Four isomeric modifications are possible, of which three are known. They have different specific gravities and boiling points. The ordinary form, is a colorless liquid of a disagreeable odor. Several valer- ates, often called valerianates, are used in medicine; among these are those of zinc and ammonium. Stearic Acid can be obtained from most of the solid animal fats, and from some vegetable fats. It is a white, crystalline body which can be dis- tilled. It is insoluble in water. Among other uses for it is the manu- facture of candles. The white candles called stearine are generally made of stearic acid. Salts of the Higher Fat-Acids.—By substituting the single atom of replaceable hydrogen of the fat-acids we obtain a series of bodies all of which might be called "soaps," but it is only with the higher members of the series that the peculiar physical and chemical characters of the soaps are seen. The derivatives of the lower members are generally soluble in water, but in the higher members most of the compounds are insoluble, except those formed by potassium, sodium and ammonium. With lead, calcium and zinc, for instance, we get insoluble soaps. SUBSTITUTION DERIVATIVES. l2l ETHERS OF THE FAT-ACIDS. The monad alcohol radicles give with these acids compounds which are more or less volatile and odorous. They are known as compound ethers or esters. The general method of preparation is to heat a mixture of the sodium salt of the proper acid with the alcohol containing the proper radicle and sulphuric acid. Thus to produce ethyl acetate we would heat sodium acetate, ethyl alcohol and sulphuric acid:— C2H5HO 4- NaC2H302 + H2S04 = C2H5C2H302 + NaHS04 + H20. By using pentyl alcohol and sodium valerate, pentyl (amyl) valerate is formed, and so on. Amyl acetate constitutes a banana essence; amyl valerate is apple essence, amyl butyrate has the odor of pine-apples. By various mixtures of these and other ethers almost any flavor may be imitated. SUBSTITUTION DERIVATIVES. The hydrogen that is part of the radicle of these acids may be substituted by members of the chlorine group, particularly by chlorine itself. From acetic we get three compounds, all of which closely resemble the original acid:— HC2H302 . HC2H2C102 HC2HC1202 HCC1302 . These compounds are usually obtained by the direct action of chlorine. By indirect means, the use of phosphoric chloride, for instance, the chlorine may be made to replace the hydroxyl of the acid; in this manner the acid properties are removed, and chlorides of the acid radicles are formed. Acetic acid gives the following:— Acetic Acid. Acetyl Chloride. CH3COOH -f PC15 = CH3COCI -f- P0C13 + HCl. Similar compounds may be obtained from bromine. 9 Acetic acid. Monochlor-acetic acid. Di " " Tri " " " 122 ORGANIC CHEMISTRY. OLEFINS, OR METHENE SERIES. The second member of this series, ethene, C2H4, was called, when first discovered, olefiant (oil-making) gas, because it combines with chlorine to form an oily liquid; for this reason the series has been called the olefins. They are dyad radicles, which form alcohols, ethers and other derivatives; but these derivatives are greater in number than from monad radicles, on account of the higher valency. Two series of acids are yielded by the action of oxygen on the alcohol, instead of one, as in the case of the monad radicles. Melting Point. F. C. 135 144 57 62 F. C. Gaseous. 0.4 —18 33-8 I 95 35 149 65 205 96 248 120 284 140 320 160 482 250 527 275 752 400 The ratio between the weights of the hydrogen and carbon is the same in each member of the series, so that the percentage composition is the same throughout the series, but the molecular weight increases. The members of the series are polymeric isomers. Ethene . . Tritene . . Tetrene . . Pentene . . Hexene . . Heptene . . Octene . . Nonene . . Decene . . Pentedecene Hexdecene ^-20"40 • • C27H54 . . ^30^80 • ■ DERIVATIVES. 123 DERIVATIVES.—The olefins combine directly with the chlorine group to form dichlorides. Ethene dichloride, C2H4C12, was originally called Dutch liquid, because discovered by an association of Dutch chemists. By indirect means oxides and ethers may be formed, and also hydrox- ides, containing, of course, two molecules of HO and known as Diatomic Alcohols or Glycols. Each of these alcohols yields by oxidation two acids, one derived by the replacement of two atoms of hydrogen by one atom of oxygen, and the other by the replacement of four atoms of hydro- gen by two atoms of oxygen. The first is the lactic acid series; the second, the oxalic acid series. For instance, ethene glycol gives the following:— Glycolic Acid. C2H4(HO)2 + 02 = H20 + HOCH2 COOH. Oxalic Acid. C2H4(HO)2 + 04 = H20 + COOH COOH. Oxalic acid is, therefore, dicarboxyl. Methene glycol, CH2(HO)2, has not been obtained. By oxidation it could form but one acid, carbonic, (HO)2CO, which may be regarded as the first member of the first series. Radicle. Oxides, Hydroxides, Acids by Acids by Ethers. Alcohols. first oxidation. second oxidation. Glycolic acid. Oxalic acid. C2H4 C2H40 C2H4(HO)2 C2H403 Lactic acid. C2H204 Malonic acid. C.H, C3H60 C3H6(HO)2 C3H6°3 . Oxybutyric acid. C3H404 Succinic acid. C4H8 C4H80 C4H8(HO)2 C4H803 C4H604 The acids of the first, containing one molecule of alcoholic hydroxyl and one molecule of carboxyl, are called hydroxy-acids. Ethene oxide, C2H40, is isomeric with common aldehyde, but is not identical with it. Acid Derivatives of the Glycols.—These are the most important. The first (lactic) series is monobasic, that is, has a single atom of replace- able hydrogen; the second (oxalic series) is dibasic, that is, has two atoms of replaceable hydrogen. 124 ORGANIC CHEMISTRY. LACTIC SERIES. Name. Formula. Melt. Pt. Boiling Pt. Source. F. C. F. C. Glycolic Lactic . . Oxybutyric Oxyvaleric Leucic . . C2H403 C3H603 C4H8°3 C5H10O3 ^6"l 2^3 176 176 164 80 80 73 212 212 IOO IOO By oxidation of ethene glycol. By fermentation of milk sugar. By oxidation of butyric acid. By oxidation of valeric acid. Occurs in animal products; also formed by decom-position of horn, glue, etc. Lactic Acid, (HO)C2H4(COOH).—This important acid exists in at least three isomeric modifications. [a) Ordinary lactic acid exists in gastric juice, and Turkey opium, and is a product of fermentation, especially of milk. It is a colorless, syrupy, very sour liquid, which has not yet been obtained in the solid state. It can be obtained in quantity by allowing a mixture of cane sugar, cheese, sour milk and chalk, or zinc oxide, to ferment for several days. The result- ing calcium or zinc lactate can be purified and the lactic acid obtained from it. [b) Paralactic acid and [c) ethene-lactic acid, two isomers of ordinary lactic acid, occur together in muscular tissue, and were formerly included under the title sarcolactic acid. Several lactates are used in medicine. Lactic acid is one of the products of the growth of fungi around the teeth, and is an important factor in dental caries. OXALIC SERIES. 125 OXALIC SERIES. Mel . Pt. Name. Formula. Source. F. C. Oxalic . . H2C204 Oxidation of sugar, starch and cellulose. Malonic C3H404 284 140 Oxidation of malic acid. Succinic C4H604 356 180 Distillation of amber; oxidation of fat-acids. Pyrotartaric C5H804 234 112 Action of heat on tartaric acid. Adipjc . . C6H804 284 I40 " " nitric on sebacic acid. Pimelic . . C7H10O4 273 134 " " potassium hydroxide on camphoric acid. Suberic . . C„H1204 257 125 Action of nitric acid on cork or castor oil. Anchoic C9H1404 241 116 Action of nitric acid on coco-nut oil. Distillation of oleic acid. Sebacic . . ^10^16^ 261 127 Rocellic C17H30O4 270 132 Exibts in some lichens. Oxalic Acid, (COOH)2.—The free acid and its salts, especially acid potassium oxalate, occur in many plants, generally in the form of crystals —called raphides—deposited in special cells in the leaves or stems. Oxalic acid forms colorless crystals, having the composition H2C204, 2H20. It is freely soluble in water, and is one of the most rapidly fatal poisons known. Death has occurred in ten minutes after administration. The antidote is lime. Preparations of the acid are sold under the mislead- ing names of salt of sorrel and salt of lemon, and used for taking out ink stains. Ammonium oxalate, (NH4)2C204, forms white crystals, soluble in water, and much used as a test for calcium compounds. Calcium oxalate, CaC204, is thrown down as a white precipitate by add- ing an oxalate to calcium chloride. It is sometimes found in the urine in microscopic octahedral or dumb-bell crystals. In larger masses it consti- tutes mulberry calculus. Succinic Acid, C2H4(C00H)2.—This occurs in amber and other res- ins ; also in small quantities in some animals. It forms colorless crystals, soluble in water. There is an isomeric modification, iso-succinic acid. Somewhat related to the series just described, although not necessarily 126 ORGANIC CHEMISTRY. referable to the same radicles, are two important vegetable acids, malic and tartaric. The relation is especially with succinic acid, from which they differ only in amount of oxygen:— Empirical Formula. Succinic...............C4H604. Malic...............• C4H605. Tartaric...............C4H6Oe. Malic Acid, H2C4H405, occurs in many sour fruits, as apples, pears and mountain ash berries. It may be made artificially from succinic acid. It is crystalline, sour, soluble in water and alcohol. The malates are mostly soluble in water. Sweet cherries contain potassium malate. Tartaric Acid, (HO)2C2H2(COOH)2, is found in many plants, but especially in grapes, where it exists as acid potassium tartrate, KHC4H406. This is somewhat soluble in water, but scarcely soluble in dilute alcohol; and hence, in the manufacture of wine, as the fermentation advances, the quantity of alcohol increases, and the tartrate deposits as a red mass called argols or tartar; when this is dissolved in water and purified by crystalli- zation it constitutes cream of tartar (sometimes called incorrectly cremor tartar). Tartaric acid presents several isomeric modifications, which recall somewhat of the different forms of glucose. The acid is a crystalline body, soluble in water, forming a very sour solution which develops a fungous growth and decomposes. Acid potassium tartrate, cream of tartar, is a white crystalline body, very sour, and not very soluble in cold water. It is used in effervescing powders. Potassium tartrate, K2C4H406, is called soluble tartar. Sodio-potassium tartrate, NaKC4H406, is known as Rochelle salt. Tartar emetic is made by boiling acid potassium tartrate with oxide of antimony, by which an atom of hydrogen is replaced by the molecule SbO. The formula for tartar emetic is, K(SbO)C4H406, potassium antimonyl tartrate. Citric acid, (HO)C3H4(COOH)3, is the acid of lemons and oranges, and is also found in some other fruits. It is a crystalline body, very sour, and easily soluble in water. It is used in the preparation of effervescing mixtures, but some of the so-called effervescing citrates contain tartaric instead of citric acid. METHENYL SERIES. 127 METHENYL SERIES. These are triad radicles. The first member, CH, methenyl may be regarded as existing in chloroform. The most important member of the group is tritenyl, C3H5, also called propenyl. Its hydroxide, C3H5(HO)3, is glycerol. Many of the common oils and fats are compound ethers of tritenyl, and when treated with alkalies, such as caustic soda, are broken up; a new salt and tritenyl hydroxide is formed. On tritenyl stearate (one of the ingredients of common animal fat) caustic soda—common lye— would act thus:— Tritenyl Stearate. Sodium Stearate. Glycerol. (C3H5)(C18H3502)3 4- 3NaHO = 3NaC18H3502 + C3H5(HO)3. Sodium stearate is a soap, and the process is saponification. The form- ation of glycerol can also be brought about by the use of superheated steam. This method is the one now generally used in manufacturing operations, since it gives the fat-acids in the free condition, thus :— C3H5(C18H3S02)3 + 3H20 = C3H5(HO)3 + 3HC18H3502. Glycerol (Glycerin), C3H5(HO)3.—The pure glycerol is a colorless, viscid liquid, miscible in all proportions with water and alcohol. Specific gravity 1.27. It has a marked sweet taste, absorbs water from the air, but does not otherwise change. Under certain conditions it can be distilled without decomposition. It solidifies at about — 400 F. and C. It dissolves a great many substances, standing, in fact, nextt to water in its range of solvent powers. It is produced in small quantity during the fermentation of sugar, hence is often found in ordinary liquors. It is sometimes called the " sweet principle of fats," but it does not exist in fats, and possesses no chemical analogy to them. It is an alcohol, and is probably somewhat analogous to the sugars. Its use, therefore, as an application to the skin as a substitute for the emollient oils has no chemical justification. When treated with strong nitric acid, it forms tritenyl nitrate, C3H5- (N03)3, known as nitro-glycerin. This is powerfully explosive, especially by percussion. It is now extensively used as a blasting agent, being generally mixed with some inert powder, such as fine silica, constituting dynamite. 128 ORGANIC CHEMISTRY. FATS AND FIXED OILS. The fats and fixed oils are almost all compound ethers of tritenyl. Most of the natural forms are mixtures of two or more distinct ethers. Names are applied to them according to the acid from which the ether is derived. Thus, tritenyl stearate, C3H5(C18H3802)3, is called stearin; tritenyl butyrate, C3H5(C4H702)3, is called butyrin, and so on. These substances, therefore, constitute the proximate principles. The fixed oils are fats with a low melting point, and may be divided into two classes; drying oils, which absorb oxygen from the air, and become hard and resinous, such as linseed and poppy oil; non-drying oils, which remain fluid, as castor and sperm oil. Many fats and oils undergo partial decomposition in the air, producing acids; this is called rancidity. When caustic alkali is added to a fat, decomposition takes place, a salt is formed, constituting a soap, and glycerol is produced. Soaps produced by potassa are usually soft; those from soda, hard; those made from other oxides are mostly insoluble in water. This latter fact explains the curdling action of limestone waters. The calcium and magnesium compounds in these waters produce insoluble soaps. When soaps of the alkali metals are treated with cold water they decompose into acid salt, which precipitates and makes the soapsuds, and a basic salt, which dissolves and gives the cleansing action. The fat-acids may be obtained by adding a strong acid to ordinary soaps. The fats are all insoluble in water, but are soluble in ether, chloroform, benzene and carbon disulphide. They are decomposed by heat, and con- sequently cannot, under ordinary circumstances, be distilled. The proximate constituents of the common fats are given under con- densed names, the significance of which is as follows:— Stearin is tritenyl stearate. Palmitin is " palmitate. Margarin is " margarate. Butyrin is " butyrate. Olein is " oleate. Human fat contains olein and palmitin. Oleic acid is not a member of the same series with the other acids. It belongs to a series beginning with acrylic acid, C3H402, and is elsewhere described. The following table of properties of the important fats and oils is con- densed from Allen's tables:— ALLYL AND DERIVATIVES. 129 Name. Sp. Gr. at Melting point, Distinctive Proximate 150 C. Centigrade. Constituents. Olive..... O.916 + 4to- • 6 Olein, palmitin and some stearin. Almond . O.918 — 10 to — 20 Olein and palmitin. Peanut . O.918 - 5 Arachidin and hypogcein. Rape . . 0915 — 6 to — 10 Biassin. Cottonseed O.926 1 to 4 Olein and stearin. Sesame . O.922 + 5to- - 6 Olein and myrislin. Linseed . o-935 — 20 to — -27 Linolein and myristin. Castor 0.960 — 18 Ricinolein and palmitin. Croton 0.950 . , Tiglin, crotonin and valerin. Palm . . 0925 25 to 36 Olein and palmitin. Cacao . . o-995 30 to 34 Olein and stearin. Coco-nut 0.874* 20 to 28 Laurin. Neatsfoot 0.915 Below 3 Lard oil . 0.915 — 4to-f IO Olein. Tallow . 0.862* 36 to 49 Olein, palmitin and stearin. Lard . . 0.861 28 to 45 " " " " Wool fat 0.888 Butter . 0.870 29 to 35 " " " butyrin. Whale . 0.925 Valerin. Cod-liver 0.927 Olein and myristin. Sperm 0.880 These contain fats derived I from other radicles than tri- Spermaceti Beeswax 0.810* 0.825* 43 to 62 to 49 64 1 tenyl, and hence do not yield * glycerin when saponified. * Taken at 99° Centigrade. ALLYL AND DERIVATIVES.—Allyl, C3H5, is isomeric with tritenyl, but unlike it is a monad, the carbon atoms neutralizing the valency of each other more completely than in the case of tritenyl. By graphic formulae the difference may be thus represented:— Trytenyl, Triad. H H —C—C—C—H 1 11 Allyl alcohol is C3H5HO. Allyl is chiefly interesting on account of the occurrence in nature of two of its compounds, allyl sulphide, (C3H5)2S, which is the essential oil of garlic, and allyl sulphocyanate, C3H5CNS, Allyl, Monad. H H C = C-C- I I I H H H 130 ORGANIC CHEMISTRY. volatile oil of mustard. Allyl aldehyde, C3H40, is one of the products of the decomposition of fats by heat, and is the main cause of the irritating vapors which are caused by such decomposition. The oxidation of allyl aldehyde gives acrylic acid, which is the first member of a series of acids derived from some of the fats. The most important of this list is oleic acid. Oleic acid, C17H33(COOH), exists in mo*t natural fats and non-drying oils as olein—tritenyl oleate. It is solid at 570 F. (140 C). Above this temperature it is a clear liquid, lighter than water, and insoluble in it, but soluble in alcohol and ether. Crude oleic acid, made by the decomposition of fats by steam, as mentioned elsewhere, is used in soap making, under the name of red oil. Various oleates, e.g., copper, bismuth, zinc and mercury oleates, are now used as substitutes for ointments. They are usually pre- pared by the reaction of sodium oleate with some suitable compound. Thus copper oleate is formed by mixing copper sulphate with sodium oleate. TURPENES. The molecule C10H16, represents the composition of a large number of volatile or essential oils. These often exist in plants, in association with oxidized products of higher boiling point, called resins, constituting an oleo- resin. When this is heated the oil distills and the resin is left. Gum is also sometimes present, thus making a gum-resin. A balsam is a similar mixture containing benzoic or cinnamic acid. Of the volatile oils having this composition, the most important is— Oil of Turpentine, obtained from turpentine, which is an exudation from pine trees, consisting of resin and volatile oil. On being distilled the volatile oil is collected in a receiver; the resin remaining constitutes com- mon rosin. Oil, or spirit of turpentine, is a thin, colorless liquid. It is lighter than water, boils at 3200 F. (1600 C), and is a valuable solvent. It is partially oxidized in the air. By passing air through warm oil of turpentine a partially oxidized product is formed, which, when shaken with water, will produce some hydrogen dioxide. The oxidized oil is now sold as a disinfectant, under the name of " Sanitas." Some of the oils which have the same composition are lemon, bergamot, coriander, hop, juniper and valerian. They are called essential oils, are mostly lighter than water, and freely soluble in ether and alcohol. Though agreeing in composition, they differ in specific gravity, boiling point and in other properties. Many of them, by exposure to the air, undergo oxidation BENZENES. 131 and other changes, in time becoming resinous and acquiring an odor some- thing like oil of turpentine. Many of the e-sential oils can be separated, by cooling, into solid and liquid portions, called respectively, the stearoptene and the olceoptene. CAMPHORS AND RESINS.—Plants furnish us with a number of oxidized turpenes, among which are the camphors and resins. Common camphor, C10H16O, obtained from the camphor laurel, is a white, crystalline solid, volatile at ordinary temperatures. It is slightly soluble in water, and freely in alcohol and ether. By the action of hydro- chloric acid on oil of turpentine a body having the odor of camphor is formed. Another form of camphor, called Borneo camphor, has the formula, ^10"l8^2- Resins include a large group, of which many are true acids, and form salts, constituting resin soaps. Common rosin is the residue from the preparation of oil of turpentine. It is a mixture of two acids. As a class the resins are easily fusible, insoluble in water but soluble in alcohol. Amber and copal are fossil resins—that is, are found in fossil vegetable matter. Lac, mastic, sandarach and dragon blood are used in varnishes. Caoutchouc and gutla percha are turpenes found in the juices of some plants. They are insoluble in water, but in the plant are usually in sus- pension, very finely divided so as to make a milky liquid, called an emulsion. Caoutchouc is elastic ; gutta percha is not. Both are capable of combining with sulphur when heated to about 3000 F. (1500 C). The process is called vulcanizing, and the hardness of the product can be regulated by the amount of sulphur and the temperature used, so that valuable materials are prepared in this way. Caoutchouc dissolves in benzene and petroleum spirit. Gutta percha is soluble in chloroform; the solution constitutes liquor gutta percha. BENZENES. Benzene, C6H6, is the first member of a series which possesses great interest on account of the number of isomeric compounds which have been obtained. The hydrogen is susceptible of replacement by various elements and radicles, and not only may we get, in this way, a number of compounds, but it appears that different atoms of H, replaced by the same substance, 132 ORGANIC CHEMISTRY. give different bodies. Thus, dibromo-benzene, C6H4Br2 exists in three different forms, called respectively ortho,meta and para-dibromobenzene. These facts are explained by graphic formulae, in which the substituting bodies are shown in different positions in the different isomers. H I H—C C—H « X H—C C—H \c// Br I H—C C—Br II I H—C C—H H Benzene. H Ortho-dibromobenzene. Br I H—C C—H II I H—C C—Br I H Meta-dibromobenzene. Br c H—C C H—C H C-H I Br Para-dibromobenzene. In such formulae it is usual, in order to avoid confusion, to write the ben- /\ zene molecule | omitting the hydrogen. The three dibromoben- zenes given above would be expressed thus :— Br Br Br /\ I I \/ Br The terms ortho, meta, and para may be abbreviated to o, m, and/. The number and complexity of the isomers generally increases as the number of the substituting bodies increases, and especially when different radicles are concerned. BENZENES. 133 It might seem that in addition to the three substitution compounds with bromine above given, the following forms should also exist:— Br Br /\ Br /\ Br I I ' II \/ \/ The first of these positions is, however, symmetrical with that represent- ing the meta form, and the second position is symmetrical with that repre- senting the ortho form, and neither, therefore, expresses a new condition of isomerism. As a matter of fact only three dibromobenzenes are known. The supposed arrangement of the carbon atoms in benzene, called the benzene ring, constitutes a simple example of the " closed " carbon chain. The molecular union is very strong, and enables the carbon to resist power- ful chemical agents, such as nitric and chromic acids, much better than is the case with the open chain compounds. The angles of the hexagon are distinguished by numbers in the order of those on the face of a clock, thus:— 6 /\ 2 5 x/ 3 4 The different substitution compounds are often indicated by these num- bers. Thus, ortho compounds are called 1-2 compounds, meta, 1-3, and para, 1-4. When three atoms of hydrogen are substituted by the same monad, three forms are produced, as follows : Br Br Br /\ Br /\ /\ 'x/'fir 'x/'Br Br'x/'Br Br Consecutive (/, 2,3) Unsymmetrical (/, 3, 4) Symmetrical (/, 3, s) Tribromobenzene. Tribromobenzene. Tribromobenzene. Comparison with other positions of the three atoms of bromine will show that the above are the only distinct forms; investigation shows that three, and only three, tribromobenzenes are obtainable. 134 ORGANIC CHEMISTRY. Substitutions of a single hydrogen atom, or of five hydrogen atoms should produce only one form, and this accords with the observed facts. The graphic formula shows that benzene contains six latent valencies, and as a result it is capable of acting as a hexad, though ordinarily it acts as a saturated molecule. The condition when these valencies are devel- oped, is easily shown. H I \C \/ \/ H—C C—H H—C C—H /\ /\ I H Benzene in this condition could take up six atoms of bromine without losing any hydrogen, forming C6H6Br6. Such bodies are called additive compounds, are much less stable than the substitutive, and of less import- ance. Care must be taken not to confound the nomenclature of the two classes of compounds. C6H6Br6, an additive compound, would be called benzene hexbromide. C6Br6, a substitutive compound in which all the hydrogen has been replaced by bromide, would be hexbromobenzene. Similarly, C6H6(HO)2 is benzene dihydroxide, while C6H4(HO)2 is dihydroxy benzene. The following are the principal members of the BENZENE SERIES. Name. Benzene Toluene Xylene Cumene Cymene Formula. C6H6 C7H8 C8H10 C9H12 Cl0"l4 Freezing point, F. Boiling point, F. 32 177 Below — 20 231 Several isomeric forms of each of these; of different freezing and boiling points. Benzene, C6H6, sometimes called benzole, may be made in several ways, among which is the destructive distillation of coal. In the manufacture of BENZENES. 135 illuminating gas from coal a quantity of tar is produced, and from this, by fractional distillation, the benzene is obtained. When pure, it is a colorless, mobile liquid. It is lighter than water, and insoluble in it; mixes with alcohol and ether, and is very inflammable. It is largely used as a solvent for resins and fats. When treated with strong nitric acid it yields nitrobenzene:— C6H6 + HN03 = C6H5(N02) + H20. Nitro-benzene is a yellow liquid, having an odor which resembles some- what that of bitter almond oil. It is now used as a cheap perfume, espe- cially in soaps, under the name of oil of myrbane. It is distinctly poison- ous, producing, even in small doses, unconsciousness, with marked delay in respiration. When nitro-benzene is heated with nascent hydrogen it is converted into aniline, C6H5H2N. By distilling nitro-benzene with sodium amalgam, azo-benzene, (C6H5)2N2, is obtained. Toluene is methyl benzene, C6H3CH3, that is, benzene in which one atom of hydroxyl has been replaced by methyl. It is a limpid liquid, lighter than water, and not solidifying at the freezing point of water. It generally exists in crude benzene. Starting with benzene, we have a series of hydrocarbons, differing by C4H2. Thus:— C6H6, . . benzene. C14H10, . . anthracene. C10H8, . naphthalene. C18H12, . . chrysene. These bodies, all existing in the destructive distillation of coal, have the common property that, under the influence of oxidizing agents, two atoms of hydrogen can be replaced by two atoms of oxygen. The bodies so pro- duced are called quinones, and by the action of nascent hydrogen they furnish hydroquinones. The character of these changes is shown by the following formulae:— Benzene. Quinone. Hydroquinone. C6H6 C6H402 C6H4(HO)2 Each one of the four hydrocarbons given above is the member of a homolo- gous series, but it will not be necessary to describe all these. Naphthalene, C10H8, sometimes called coal-tar camphor, is obtained from coal tar, in the form of white, somewhat fragrant, crystalline scales. It melts at 1760 F. (8o° C). It is slightly soluble in boiling water. It is 136 ORGANIC CHEMISTRY. used extensively to protect goods against moths. Naphthalene consists of a double ring of carbon atoms saturated with hydrogen; thus,— H H J C H—C C C—H II I I H—C C C—H \c^\ •.......•.........[ 5.00 1 Fatty matter,.............. L Salts,.................J 100.00 MILK. Milk is a liquid, secreted by a special gland, called the mammary gland, the presence and function of which is characteristic of a class of animals [mammalia) the highest in the scale of organic nature as known to us. It consists of a clear liquid, holding in suspension butter-fat, in the form of distinct globules, about .0002 of an inch in size, each surrounded by an albuminous envelope. Its composition differs slightly in different animals, but, for the same animal, is pretty constant. Cow's milk has been most extensively studied. It and human milk are, of course, the most important. The composition of human milk is erroneously given by many authorities. 166 ORGANIC CHEMISTRY. Dr. Arthur V. Meigs, of Philadelphia, has shown that the quantity of casein does not usually exceed one per cent. The following table shows the comparison between cow's milk and human milk :— Cow's Milk. Human Milk. Vieth. A. V. Meigs. Water.......... 88.07 87.2 Fat,.......... 3-22 4-3 Sugar,......... 4-97 7-4 Albuminoids (casein),. . . 3.15 1.0 Salts,......... 0.75 0.1 100.16 100.00 The specific gravity of both milks is about 1.030. The composition of butter-fat, and the general nature of the milk sugar, have been considered elsewhere. Casein is referred to among the albumi- noids. The salts of milk are the potassium and sodium chlorides and phosphates. The reaction of milk appears to be not constant; it is gener- ally, but not always, slightly alkaline. If rendered distinctly acid, the casein becomes insoluble and precipitates, carrying with it most of the milk globules; the precipitate is the curd ; the clear liquid, the whey. The relation, therefore, of fresh to curdled milk is somewhat like that of fresh to clotted blood, the butter globules corresponding to the corpuscles, and the casein to the fibrin. The so-called spontaneous curdling of milk occurs from the milk sugar undergoing the lactic acid fermentation, under the influence of microbes. In this fermentation of lactic acid some of the milk sugar is converted into glucose, and this latter may undergo conversion into alcohol. The alcoholic liquid thus obtained is called koumis. Milk is a perfect diet, containing all the classes of nourishment. Cream is only milk rich in oil globules. Normal milk sometimes becomes highly albuminous, and acquires a condition of " ropiness." Colostrum, the first secretion of the mammary gland, is peculiar in several respects. It is denser than ordinary, the specific gravity being about 1.045 to 1-05o. The fat is aggregated into much larger masses, and albumin is present, sometimes, in considerable amount. DIGESTIVE SECRETIONS. From the mouth to the terminus of the intestine extends an unbroken line of mucous membrane, every point of which possesses secretive powers more or less distinct in different parts. In addition to the various secretions thus SALIVA—GASTRIC JUICE. 167 introduced, a number of special glands located outside of the limits of the mucous membrane empty, by means of ducts, their secretions into the digestive tract. The first of these is the— SALIVA. Saliva is the secretion of several glands. It is obtained pure only with difficulty. Human saliva is a turbid, opalescent, viscid and feebly alkaline fluid, of low specific gravity (1.005). Its composition is given as— Water,....................99-42 Ptyalin,.................... 0.14 Mucin and epithelium,............. 22 Salts,.................... 0.22 100.00 Ptyalin is a body not precisely an albuminoid, but somewhat analogous thereto. Its composition has not been accurately determined. Its special function is the power of converting starch into sugar. Its solution is not coagulated by heating. The saliva also contains potassium sulphocyanate, KCNS, the function of which is not known. While the secretions of the mouth remain alkaline there is a tendency to deposit calcium compounds on the teeth. This constitutes tartar, and although it protects the body of the tooth it has an injurious effect on the gums. Under some conditions the secretions of the mouth become acid; tartar is then no longer deposited, and the decay of the teeth is usually hastened. The average amount of saliva secreted in twenty-four hours is between two and three pints. GASTRIC JUICE. Gastric juice is secreted by a special set of glands which are especially excited to action by the presence of food. The secretion is a thin, glairy fluid, of a yellowish tint and somewhat variable in composition. It is, as usually obtained for examination, mixed with some saliva. Its specific gravity is not constant, being generally about 1.010. It does not coagulate on boiling and is less liable to putrefaction than other secretions. The exact amount of gastric juice secreted in a given time and the composition of it is differently given by different authorities, partly on account of difficulty of obtaining it pure, partly because of the want of exact methods of analysis. 168 ORGANIC CHEMISTRY. Two important constituents are, however, characteristic of it, free hydro- chloric acid and a nitrogenous ferment, pepsin. The principal ingredient is water. The following is given as an analysis:— Water....................99 44 Pepsin and other organic matter,.........32 Hydrochloric acid................25 Sodium chloride,................14 Potassium " ................05 Calcium " ................006 " and magnesium phosphates,.......015 100.221 Some observations indicate a variation of from 0.32 to 0.5 per cent, in the amount of hydrochloric acid, the average being about .17 per cent., or 1.7 per 1000. The quantity of the secretion has been estimated at from sixteen pounds to thirty-one pounds in the twenty-four hours. As mentioned above, the characteristic and important ingredients are the hydrochloric acid and pepsin. It appears, however, that other acids are occasionally present, especially lactic acid. The acidity has been ascribed to acid phosphates. Pepsin.—This is a nitrogenous ferment which may be obtained by various methods, from the gastric juice of various animals. It resembles albumin, but is not identical with it. As usually obtained, it is a grayish- white powder, insoluble in pure water, but soluble in dilute acids. Its important property is its power to render soluble and diffusible, albuminous bodies, such as white of egg. The presence of an acid is required for the process. The pepsin is not destroyed in the process, but appears to act only by its presence. The albuminous bodies are changed into forms called peptones. The proportion of pepsin required to change a certain amount of albumin is very small. This process is digestion ; it is exerted with nitrogenous forms of food; the oils, fats, starches and sugars are not affected. The process of digestion is interfered with by the absence or great excess of free acid, and by the presence of alcohol. Peptones.—These are products of the action of gastric juice on albu- minoids, and are not yet completely understood. They differ from ordinary albumin in having an acid reaction and not being so readily coagulable by heat or mineral acid. They turn the plane of polarized light to the left. Peptones sometimes appear in the urine. BILE. 169 BILE. Bile is secreted by the liver, the largest secreting organ in the body. It is a yellowish-green, viscid liquid, of specific gravity about 1.020. If it be freed from intermixed mucus it loses its viscidity and shows but little tend- ency to putrefaction. It has a bitter taste and an alkaline reaction. The composition of human bile is thus given by Frerichs, from an analysis of a sample taken from the gall bladder of a man killed by an injury:— Water,....................85.92 Inorganic salts,.................78 Mucus and pigment,.......'....... 2.98 Bile salts,.................. 9.14 Fat,...... .............. .92 Soaps, Cholesterin, }•..................26 Lecithin, The quantity secreted is estimated at about forty ounces in twenty-four hours. This is all poured into the intestines, but the greater part of it is reabsorbed. An important property of bile is its reaction with fatty substances. It emulsifies them, that is, breaks them up and renders them miscible with water. By such action the fatty matters of the food are subdivided suffi- ciently to allow of their absorption by the lymphatics of the intestine. In the intestinal canal, bile is supposed to act, in addition to its digestive func- tions, also as an antiseptic and mild stimulant to the muscular coat. The inorganic constituents of bile are water, chlorides and phosphates, and need no special mention. The principal organic constituents are sodium glycocholate and taurocholate, cholesterin, and several pigments. It contains no albumin. The glycocholate and taurocholate can be decom- posed by sulphuric acid and the free acids thus obtained. Although not existing in bile in the free state, their properties are of interest, and have been alluded to in connection with the descriptions of taurin and glycocin. Taurocholic acid contains sulphur; glycocholic acid does not. Cholesterin, another important ingredient of the bile, is elsewhere described. Bile Pigments.—Several bile pigments exist. Three have been dis- tinctly indicated and analyzed, viz., bilirubin, biliverdin, and bilifuscin. 12 170 ORGANIC CHEMISTRY. Bilirubin, C8H9N02.—This is, according to Thudichum, a monobasic acid, and exists in bile in the form of a calcium salt. When liberated by the action of acids it forms a powder of a brilliant red color, insoluble in water, alcohol and ether, but soluble in chloroform. Nitric acid containing nitrous acid produces with bilirubin a play of colors, from green, through blue, violet and red, to yellow. The final product of the reaction is choletelin, said to be identical with urinary pigment. This reaction is utilized as a means of detecting traces of bile in organic fluids. Bilirubin is supposed to be the substance which gives the yellow color to the skin in jaundice. Biliverdin, C8H9N02.—This coloring matter is produced when bilirubin is dissolved in caustic alkali and exposed to the action of oxygen for some time. Bilifuscin, C9H11N03.—This coloring matter can be obtained directly from bile or from gall stones. Sodium taurocholate and glycocholate give, with a mixture of sulphuric acid and sugar, a violet color, which has been called Pettenkofer's reaction- It was at one time supposed that bile products were the only ones that would give this, but other bodies which give it are now known. Still, with proper manipulation, this reaction is a good test for the presence of bile. Some substances give the reaction with sulphuric acid alone, but these are nearly all glucosides, and under the influence of the acid they yield the glucose which is necessary for the test. PANCREATIC SECRETION. Pancreatic Juice is a viscid alkaline secretion, of a specific gravity about 1.008. It contains about ten per cent, of solids, and, unlike bile and gastric juice, is liable to putrefaction. Its functions are somewhat similar to those of the saliva; the pancreas has been called by physiologists the abdominal salivary gland. The exact composition of pancreatic juice is not yet made out. The following is given as an approximation :— Water,...... Organic matter, . . Sodium chloride, . Free alkali, .... Sodium phosphate, . Sodium sulphate, . Other inorganic salts, 90.07 9.04 o-73 0.03 0.04 0.01 0.08 THE INTESTINAL JUICES—EXCRETIONS—SWEAT. 171 The pancreatic secretion contains three digestive ferments : trypsin, which has the power to convert albumin into peptone in alkaline solution; a dias- tatic body, probably identical with ptyalin, which converts starch into sugar, and a substance capable of emulsifying fats. The amount secreted is small; about five ounces in the twenty-four hours. The special chemical actions of the pancreatic juice are, to convert starch into sugar and to emulsify fats. THE INTESTINAL JUICES. In addition to the digestive secretion considered above, the glands of the intestines throw out secretions amounting, according to some authorities, to ten ounces in the twenty-four hours. Very little is known of the composition of these secretions, on account of the difficulty of obtaining them pure and in sufficient quantity. Some writers have described the intestinal juice as a viscid, transparent, alkaline secretion, which is coagulated by some sub- stances, and contains from two to two-and-a-half per cent, of solids. Its chemical action on the food is supposed to be about the same as that of the pancreatic juice. EXCRETIONS. A considerable number of products formed in the animal system are of such a character that they must be removed sooner or later from the body, or injury to health will result. For some of these the special secretory organs are provided, and, consequently, such products are both secretions and excretions. Two of these will be here considered: sweat and urine; the first the secretion of the skin, the second, of the kidneys. The two organs stand to each other in a vicarious relation; that is, one is capable, to a certain extent, of performing the functions of the other; but this substitu- tion is not perfect. SWEAT. This term includes only the fluid portion of the secretion, but experiment has amply demonstrated that carbonic acid gas is also given out, although only in small proportion. The water, for the most part, passes off in an insensible form, being carried away in solution in air surrounding the body; but when this air is saturated with moisture, or when the secretion of sweat becomes much increased, the water accumulates on the surface of the skin in the form of drops. From various experiments it has been concluded that 172 ORGANIC CHEMISTRY. the amount of water passed off by the skin in twenty-four hours is about two pounds; the amount of carbonic acid is only about ^ of that given off by the lungs. Very little is known about the solid contents of the sweat. Its composition is probably variable, even within the limits of health, and undoubtedly considerable changes take place in disease. The results of analyses are not very satisfactory:— Water, Solids, Urea is generally present in small amount, and the secretion is sometimes acid from the presence of free fat-acids. URINE. Characteristics of Normal Urine.—It is a clear, pale yellow or amber- colored fluid, of acid reaction. Its specific gravity within the limits of health may vary from 1.018 to 1.030. The quantity passed in the twenty- four hours maybe approximately fixed at fifty fluid ounces—about fifteen hundred cubic centimetres. Average composition of normal urine passed during twenty-four hours by an adult man weighing 140 pounds:— Urea,..............30 to 40 grams. Uric acid,...............0.5 " Kreatine,...............0.3 " Kreatinine,...............0.45 " Hippuric acid,.............0.5 " Acetic acid,..............0.288 " Formic acid,..............0.050 " Sodium and potassium chlorides,.....12.00 " Sulphuric acid (as sulphates), ......2.00 " Other sulphur compounds,........0.2 " Calcium phosphate,...........0.5 " Magnesium " ...........0.6 " Alkaline phosphates,..........1.9 << In addition to these ingredients many others are present in very minute amounts, among which may be mentioned phenol sulphonate. URINE. 173 Urea, CH4N20.—This is almost always present in the urine, and except in disease, is its most abundant solid constituent. It is isomeric with ammonium cyanate, (NHJCNO, and can be formed from it. Its rational formula is generally given as (CO)H4N2, being diamine in H6N2 in which two atoms of hydrogen are replaced by the acid radicle (CO). It ought, therefore, to be called carbonyl diamide. It is a colorless, easily crystalliz- able solid, soluble in its own weight of water; also soluble in alcohol. It is decomposed by heat and by many chemical agents. In the presence of putrefying or fermenting substances it takes up two molecules of water and becomes ammonium carbonate :— CH4N20 4- 2H„0 = (NH4).2C03. The reaction does not occur with a pure solution of urea in water, but quickly occurs in ordinary urine, on account of the decomposition of the mucus. By this reaction stale urine becomes alkaline. With sodium hypobromite or hypochlorite, urea is decomposed, nitrogen and carbon dioxide being given off in the free state. Urea is a base forming a series of well-marked salts, in which, as in the case of the organic bases generally, the acid unites without loss of hydrogen, but only one molecule of acid is taken up. Urea nitrate, for instance, is CH4N20,HN03, and urea oxalate is (CH4N20)2H2C204. Both of these salts are but sparingly soluble in water. Urea also combines with mercury oxide and with mercuric nitrate. It exists in the urine in the free state. Uric Acid, H2C5H2N403—This is contained in urine only in small quantity in health. It is a very common ingredient of urinary calculi and deposits. It is a white, crystalline powder, almost insoluble in cold water. It forms two classes of salts, acid and normal. They are, in general, more soluble in water than the free acid. The normal urates are easily decom- posed. When uric acid or urates precipitate from urine they generally carry down with them some of the coloring matters of the liquid. The urine passed during twenty-four hours does not normally contain more than eight grains. Xanthine, C5H4N402, which differs from uric acid only by having one less atom of oxygen, is present in small amount in normal urine. Very rarely it is encountered as a form of calculus. It forms white, amorphous granules, and yields compounds with acids. Hippuric Acid, HC9H8N03.—This substance is present only in small quantity in human urine, about one gram being passed daily. Absolutely reliable analyses of urine can only be made on samples that are less than twenty-four hours old. 174 ORGANIC CHEMISTRY. Specific gravity is generally taken by means of a urinometer, which is a graduated bulb-tube weighted so as to float upright. Extreme accuracy is not required, a difference of a few degrees not signifying anything clinically. In using the urinometer the following precautions are neces- sary :— (a) The urine must be at a temperature near 60° F.; the determination should not be made when the liquid is first passed. [b) The instrument must be placed in carefully, and the glass vessel must be wide enough to allow it to float freely. [c) In reading the gravity the eye should be placed on a line just below the level of the liquid. This is to avoid the error due to the curved line which the liquid makes with the graduated stem. For instance, in the annexed diagram the a- j, reading should be along the line a b, not along c d, the latter being only the apparent level. The cheaper forms of urinometers are usually quite sufficient for clinical purposes. It is advisable to test the instrument by placing it in water at a temperature of 6o° F., and noting whether it sinks to the 1000 mark. Reaction.—Urine, when fresh, is generally decidedly acid, due, probably, to acid sodium phosphate, but when uric and hippuric acids are in excess they may also contribute to the acidity. The acid reaction increases slightly after the urine has been passed, but very soon the mucus begins to decom- pose and causes the urea to become ammonium carbonate. The liquid becomes alkaline and very foul. A neutral condition or transient alkalinity is seen in the urine secreted just after a meal, and an alkalinity due to decomposition is noticed in those cases in which, owing to obstruction, the liquid is retained in the bladder for some time. For determining reaction, litmus paper is suitable. A solution of litmus is prepared by boiling it in water; this is divided into two parts, to one of which some strong acid is added, drop by drop, until the color is wine-red. This is then mixed with the other half of the liquid. Slips of filtering paper are dipped in this liquid and dried. They will assume a purple tint and are very delicate, responding either to a trace of free acid or URINE. 175 of alkali. By employing this form of paper we avoid the necessity of using two colors. The paper should be cut into pieces about one-half an inch square, one of these being dipped into the sample to be tested. Of course, no piece should be used a second time. Litmus paper is best kept in a closed bottle away from the light, but litmus solution must be kept in an open bottle. It will then keep for a long time, while in a closed bottle it will soon decompose. The principal coloring matter of normal urine is urobilin, an oxidation produced from blood. In febrile conditions a less oxidized body occurs, which MacMunn has called pathological urobilin. Abnormal Coloring Matters.—These include various modifications of the blood-coloring matters, a special color known as uroerythrin, biliary products and color due to articles of food. Blood Colors.—These give to the urine a smoky color when in small amount; large quantities color it red. When blood itself appears in urine the corpuscles may be recognized by the microscope, and the condition is called hamaturia, but if only the coloring matters of the blood are present the condition is called hamalin- uria. In the latter case the abnormal ingredients are recognized by spectroscopic and chemical methods. The test is to add to the liquid a small amount of tincture of guaiacum and a few drops of ether containing hydrogen dioxide. If blood products be present a blue color will be im- parted to the ether. The ethereal solution of hydrogen dioxide may be prepared by adding barium dioxide to slightly diluted hydrochloric acid and shaking the mixture with ether. Hydrogen dioxide is formed, and taken up by the ether, which may be easily decanted from the acid liquid. The solution does not keep very well. Biliary Coloring Matters.—When these are present in decided amount they give a yellow color to the urine. The test is with fuming nitric acid, which gives a series of colors in the order, green, blue, violet and yellow. The green color at the beginning is especially typical. The test is best performed by placing on a plate a drop or two of the urine and of the test liquid, and allowing the two to mingle slowly. Chlorides are diminished during febrile conditions; sometimes entirely absent. They may be at once recognized by adding a few drops of nitric acid, and then silver nitrate. A white precipitate is formed if chlorides are present. Phosphates.—Potassium and sodium phosphates are called alkaline phosphates; calcium and magnesium phosphates are called earthy phos- 176 ORGANIC CHEMISTRY. phates. The former are soluble in water; the latter not; both are soluble in acids. The amount held in solution depends in part on the amount of acid, also on the temperature. These facts are important, because a deposit of phos- phates may occur, either from alkalinity or deficient acidity of the urine, or from actual excess of the phosphates themselves. The clinical significance of these conditions is, of course, very different. By means of litmus, as already given, the reaction of the liquid can be easily ascertained. Deposits of phosphates are generally bulky and white, remaining undissolved when the liquid is boiled—being thus distinguished from urates—but dissolving in hydrochloric or nitric acid. Such deposits have no significance when found in urine which has become stale and has thus acquired an alkaline reaction. Phosphates are deposited in various forms, which are, in the main, dis- tinguishable from each other and everything else by the microscope. Oxalates.—Calcium oxalate, CaC204, is the only one requiring notice. It is deposited in the minute but very distinct octahedral crystals and also in dumb-bell forms. Uric Acid.—Excess of uric acid is usually shown by a brick-red deposit of small crystals. Under the microscope, even with a low power—40 to 60 diameters—these show various forms, generally lozenge-shaped. A deposit of urates may be recognized by the red color, and by dissolving in whole or in part by heating the liquid in which it is suspended. Uric acid, or any of its compounds, may be recognized by the so-called murexide test. The sediment is treated on a watch glass or cover of a porcelain crucible, with a drop or two of nitric acid—not very strong—and then carefully evaporated to dryness. A drop of ammonia is then added, and if uric acid is present a purple color will be produced. Albumin.—The tests for albumin are all dependent on its coagulation. The liquid should always be filtered before the tests are applied and its reaction noted. Heat.—Ordinary forms of albumin are rendered insoluble by a heat of about 1500 F. (650 C), especially in the presence of free acid. Alkaline solutions are sometimes difficult to coagulate. In the practical application of the heat test a test-tube should be about one-third filled with the urine and boiled for a few seconds, and then, whether a precipitate is produced or not, a few drops of nitric or acetic acid should be added. If a pre- cipitate remains after the addition of the acid, the presence of albumin is in- URINE. 177 dicated. A precipitate produced by boiling but dissolved by the acid is due to phosphates and may be disregarded. Nitric Acid, Heller's Test.—This acid produces coagulation in the cold, and gives us a method but little liable to fallacy. About fifteen drops of commercial nitric acid are placed in a somewhat narrow test-tube, and about a drachm of urine poured slowly down upon it, holding the tube con- siderably inclined. Another method, and one preferred by many, is to put the urine in first and pour the acid down the side of the inclined tube, when it will run below the urine and form a clear layer at the bottom of the tube. For this and all other tests in which heat is not required, the test-tube designed by Mr. J. A. Kyner, of the Philadelphia Polyclinic, will be found very suitable. To use it the test material is put into the tube and then a piece of filter paper adjusted in the funnel-shaped top, so that the filtrate will run down the tube ; the urine is then poured on the filter and will soon run through. Any precipitate at the point of contact will be at once seen. Fallacies.—Urine rich in urea sometimes gives a precipitate of urea nitrate, which might be mistaken for albumin. It can be distinguished by its solubility when warmed, and by its crystalline character. Excess of urates may also produce a misleading precipitation, but the ring produced by these is generally more irregular, and after a few hours is converted into the crystalline uric acid, which is easily recognized under the microscope. In exceptional cases resinous bodies which have been given as medi- cines may be found in the urine in combination with the bases present. Such compounds may be decomposed by the acid and the resin precipitated as an amorphous mass, which may simulate albumin. The distinction will be the odor of these resins and their solubility in strong alcohol. In addi- tion to these points, the fact of their being administered will suggest pre- caution in regard to the test. Picric Acid.—Saturated solution containing also two drachms of citric acid to the ounce. This is considered a delicate test, but precipitates with bodies other than albumin. As has been recently shown, non-albuminous urine of persons taking quinine will give a precipitation with this test; so also will the partially transformed albumins known as peptones. Metaphosphoric Acid, Glacial Phosphoric Acid.—This is a very delicate test, and has the advantage of producing no color with the urine, thus permitting the most minute coagulum to be observed. It is applied by dropping into the filtered urine a fragment about the size of a cherry stone, and allowing it to remain for a few minutes without heat or stirring. 178 ORGANIC CHEMISTRY. A white coagulum is formed around the fragment, if albumin is present; if none is present, a clear, syrupy solution will be produced. The acid must be kept in the solid state. Trichloracetic Acid, HC2C1302.—This is a white, crystalline, deli- quescent solid, which dissolves easily in water. It is employed in the same manner as metaphosphoric acid, but, as it dissolves more easily, the coagu- lation occurs more rapidly. Of the pro'eid bodies usually occurring in urine, all but the peptones are precipitated by saturating the liquid with ammonium sulphate. This is easily done by adding the powdered material until no more is dissolved. Ovalbumin, seralbumin, paraglobulin and the albumoses are separated, and may be collected on a filter. To detect peptones, the filtrate should be treated with a drop of a solution of copper sulphate and then considerable caustic soda added. A pink color shows the peptones. To detect and distinguish the different proteids thrown down by the am- monium sulphate, the precipitate is washed, while on the filter, with some solution of ammonium sulphate and then dissolved by the addition of dis- tilled water. Ovalbumin is coagulated by ether, seralbumin is not. Para- globulin and albumose are precipitated by saturating the liquid with mag- nesium sulphate. By collecting the precipitate so formed, adding to it boil- ing water and adding a few drops of acetic acid, albumose will dissolve, paraglobulin will not. Mucin.—This is very often present in normal urine and may become abundant in irritated conditions of the genitourinary organs. It is pre- cipitated by strong acids and alcohol, but not by boiling. When urine is filtered on to strong citric acid solution, mucin will show a faint white cloud at the point of contact. If to a urine containing mucin, two volumes of strong alcohol be added, all the mucin and albumin will be precipitated. After standing for a few hours the liquid should be filtered, the precipitate washed with alcohol, treated with warm water, and again filtered; the filtrate will contain the mucin, which will respond to tests with strong acetic acid. Pus.—Pus is detected by the microscope, by which its cells maybe seen in abundance; the liquid itself will give reactions for albumin. If a solu- tion of caustic soda be added to urine containing pus, and the mixture poured a few times from one test to another, it will become very thick and viscid. Sugar.—Trommer's Test.—Add to about I fluid drachm of filtered urine enough copper sulphate solution to give a faint greenish-blue tinge, QUANTITATIVE analysis. 179 and then at least twenty drops of a strong solution of caustic soda, and boil. If sugar be present, a greenish-yellow precipitate will form, which becomes, on further boiling, of a bright salmon color. If no sugar is present the precipitate will be bluish-green, and upon further boiling will turn black. A light brown, flocculent precipitate is often produced in urines free from sugar, and must not be mistaken for sugar reaction. Allen recommends the following for doubtful cases : Heat to boiling ten cc. of Fehling's solution, and add a nearly equal quantity of the urine ; heat again for a few minutes, and allow to cool. If no turbidity is produced as the liquid cools, the urine contains less than ^ of one per cent. Soldaini's Test.—Copper carbonate, obtained by precipitating copper sulphate with sodium carbonate, filtering and washing the precipitate, is dissolved in about 25 times its weight of acid sodium carbonate (baking soda), and the blue solution allowed to settle until clear. When this is boiled with urine containing sugar, the red precipitate is thrown down in its usual form. Milk sugar also causes the same action, but cane sugar does not. ^Boettger's Test.—Add to a filtered urine about half its volume of solution of caustic soda, and then a pinch of pure bismuth subnitrate. Shake the mixture and boil for a minute or so. Presence of sugar will be indicated by a black precipitate of metallic bismuth. If sugar is not present the precipitate will be white, or at most, somewhat gray. The action does not take place unless considerable free alkali is added. This test is very delicate and tolerably free from fallacy. Dark-colored urines of high gravity generally produce a gray precipitate, which might be mistaken as an indication of the presence of small amounts of sugar. The precipitate is not so heavy as metallic bismuth, and does not settle so rapidly nor so completely to the bottom of the tube. For proper use it is well to purify the commercial bismuth nitrate by dissolving it in nitric acid, adding a few drops of hydrochloric acid, filtering and pouring the filtrate into a large volume of cold water. The precipitate collected, washed and dried is in excellent condition for use. QUANTITATIVE ANALYSIS. Albumin.—According to Hoffmann and Ultzmann, the white zone pro- duced in the cold nitric acid test may be used as a fair approximation of the amount of albumin present. If this zone has the depth of from one- tenth to one-eighth of an inch and appears clearly defined only against a 180 ORGANIC CHEMISTRY. dark ground, the amount of albumin is less than one-half of one per cent. If the zone be between one-sixth and one-quarter of an inch deep, granular, opaque and visible without a dark background, the amount is about one- half per cent. If the albumin becomes flocculent and separates in lumps, the amount is from one to two per cent. The quantity of albumin does not usually exceed one-half of one per cent. The practice of boiling the urine and, after adding acid, noting the bulk of the precipitate, is of no value. Such phrases as one quarter or one-half albumin, often used to express these results, are incorrect. Sugar.—The most suitable method for clinical purposes is the volumetric estimation by Fehling's solution. This must be accurately made accord- ing to the following formula given by Allen, which agrees with the usual formula except that the amount of Rochelle salt is slightly increased. 34.64 grammes of pure crystallized copper sulphate are dissolved in dis- tilled water and the solution made up to 500 cc. 70 grammes of caustic soda (in sticks) and 180 grammes of Rochelle salt are dissolved in 400 cc. of water and the solution made up to 500 cc. Each solution should be kept in a well-corked bottle. For use, equal bulks of the two liquids are mixed. To determine the proportion of sugar, ten cc. of the mixed solu- tion is put into a porcelain basin, diluted with water, and the liquid brought to boiling; a few fragments of clay pipe may be added to prevent bumping. The urine is then added by measured portions and the liquid withdrawn from the heat after each addition, and after a moment's rest the basin is tilted slightly, so that the color of the solution can be seen against the white surface. The porcelain dish with handle, called the casserole, is suitable for this work. If the liquid thus examined show a blue tint, the basin must be placed again on the flame until boiling begins, another por- tion of urine added and the result noted as before. When no more blue tint is seen, the quantity of urine used should be noted and the experiment repeated after carefully washing out the basin. Each ten cc. of Fehling's solution prepared as above is equal to 0.05 gramme of sugar. To get accurate results the quantity of sugar should not exceed one per cent. If more than this is present, the urine should be diluted sufficiently and the test repeated. Urea.—Quantitative determinations are generally made by means of hypochlorites or hypobromites, which decompose the urea completely by the reaction:— CH4N20 + 3NaC10 = 3NaCl + C02 4- 2H20 + N2. If an alkaline solution is used the C02 will be absorbed, and the volume QUANTITATIVE ANALYSIS. 181 of N will be proportioned to the urea present. Hypochlorites do not produce so complete an action as hypobromites, so that the latter are usually pre- ferred, although less convenient, requiring to be prepared as needed. It is stated that the commercial sodium hypochlorite, Labarraque's solution, may be made sufficiently active by adding potassium bromide in the pro- portion of one gram to twenty-five cc. of the hypochlorite solution. Many forms of apparatus have been suggested. The cut shows a simple one devised by Dr. C. A. Doremus.* Sodium hypobromite solution is prepared by dissolving 170 grains of caustic soda in four ounces of water, and adding 80 minims of bromine. It does not keep well, and, therefore, should be prepared as wanted, but it may be preserved for a short time in a tightly stopped bottle away from the light. Bromine is extremely irritating and corrosive, and the solution should be made in the open air or in a well ventilated apartment. To use the apparatus, it is filled with the hypobromite solution so that when placed, as in the cut, the liquid partly fills the large bulb. A large * I am indebted to Messrs. Bullock & Crenshaw for the loan of this cut. The appa- ratus is graduated so as to enable the operator to read off at once the amount of urea in the urine used. Full directions are furnished with each instrument. 182 ORGANIC CHEMISTRY. watch-glass, or shallow dish, may be placed under the tube to catch any overflow. A measured quantity of the urine is then introduced by means of the dropping tube, the opening of this being pushed well into the bend of the upright tube. It is well to tilt the apparatus a little forward to insure that no gas bubbles or urine escape into the large bulb. After about twenty minutes the volume of nitrogen gas is read off. I cc. of nitrogen may be taken to correspond to .0028 of a gramme (.04 grain) of urea. The method should be tried on samples of normal urine, to familiarize the opera- tor with the manipulations. Phosphoric Acid.—The best process of estimating this body would be to acidify a known volume of the urine with nitric acid and add solution of ammonium molybdate. After standing for an hour or so in a warm place the precipitate—ammonium phosphomolybdate—is collected on a filter, washed with water acidulated with nitric acid, then dissolved in dilute ammonia. To this solution is added a mixture of magnesium sulphate and ammonium chloride (1), and the resulting precipitate is collected on a filter, washed with very dilute ammonia water, dried, burned and weighed. The weight multiplied by 0.64 will give the amount of phosphoric anhydride, P2O5. Several approximate methods have been devised. For the so called earthy phosphates, Hoffmann and Ultzmann recom- mend that a test tube, about six inches in length, and three-quarters of an inch wide, should be filled one-third full with the clear urine, and a few drops of ammonia or caustic soda be added, and the mixture heated slightly. The phosphates will separate in flakes, and in fifteen minutes will have subsided, if the tube is left at rest. If the layer of sediment is about one-third of an inch high the amount is normal; any marked departure from this can be easily noted. The alkaline phosphates may be estimated by adding to the urine about one-third its volume of a mixture made with about equal parts of magne- sium sulphate, ammonium chloride and ammonia, dissolved in about eight times the quantity of water. A normal quantity of alkaline phosphates will give with this mixture a uniformly milky appearance. URINARY SEDIMENTS. The sediments which form in urine may be either organized or unorgan- ized. All the forms require the microscope for their satisfactory identifica- tion. The organized sediments are principally tube casts, blood or other URINARY CALCULI. 183 corpuscles, epithelial cells, and spermatozoids. Many matters entirely for- eign to the urine may find their way into it, either by design or accident. I have known a deposit of collodion and iodoform to be mistaken for a urinary sediment, and attempts made to induce physicians to believe that a piece of brick was a urinary calculus. Those who use the microscope for urinary analysis should familiarize themselves with the appearance of com- mon objects, such as hair of various kinds, cotton and other fibres, frag- ments of wood, milk globules, etc. The unorganized sediments are principally uric acid, urates, phosphates and oxalates. Uric acid is generally in lozenge- or boat-shaped crystals. Urates are indistinctly crystalline; phosphates are generally in distinct prismatic crystals; oxalates in small, regular octahedra. URINARY CALCULI. The common forms of urinary calculi are composed of either uric acid, earthy phosphates, or calcium oxalates. Potassium, sodium, or calcium urate, may also be found, and two bodies—xanthine and cystine—are found quite rarely. The common calculi are generally mixtures of several of the above mentioned bodies. Calcium oxalate and uric acid often form the nuclei around which other matters deposit. The distinction of the different forms is based principally on the action of heat. I. A portion of the calculus is heated to redness on a piece of platinum foil. a. No residue is left. See 2. b. A fixed residue is left. See 3. 2. Apply the murexide test, page 176. If this gives a result, the calculus is either uric acid or ammonium urate. If no result occurs, the substance is either xanthine or cystine. See 5. 3. Add a drop of hydrochloric acid to the residue, when cold. a. It effervesces. The original body was either a urate or oxalate. See 4. b. It does not effervesce. The calculus is a phosphate. The result may be confirmed by dissolving a portion of the calculus in hydrochloric acid, and adding solution of ammonium molybdate; a yellow precipitate will be formed. 4. Apply the murexide test to a portion of the original body. If it responds, the body is a urate ; if not, an oxalate. 5. The solution of the original body in nitric acid turns yellow on evapo- ration, and leaves a residue insoluble in potassium carbonate: xanthine. The solution in nitric acid turns dark brown and leaves a residue soluble in ammonia: cystine. 184 ORGANIC CHEMISTRY. ANTIDOTES TO COMMON POISONS. Mineral Acids.—Baking soda, magnesia, chalk, lime, washing soda, soap. Caustic Alkalies.—Weak acids, vinegar, lemon juice, fixed oils. Oxalic Acid.—Lime, magnesia, chalk. Carbolic Acid.—Sodium sulphate, oils, albumin. Tartar Emetic.—Vegetable astringents, tannin, green tea. Corrosive Sublimate.—White of egg or other form of albumin. Copper Sulphate.—White of egg, oils. Sugar of Lead.—Soluble sulphates, especially magnesium sulphate or sodium sulphate. Arsenic.—Ferric hydroxide, freshly prepared. Silver Nitrate.—Common salt. Iodine.—Flour paste or starch water. Zinc Chloride.—Albumin. Phosphorus.—Magnesia, old oil of turpentine, sanitas fluid. Alkaloids Generally.—Animal charcoal and vegetable astringents. Hydrocyanic Acid.—A mixture of ferrous and ferric salts with sodium carbonate. SYMBOLS, VALENCIES AND ATOMIC WEIGHTS. 185 SYMBOLS, VALENCIES AND ATOMIC WEIGHTS. Element. "o e >> t/3 Valency. X. .£? 'v o B o < Element. "3 ja S >> Valency. M S3 0 E 0 < Aluminum, . Al IV 27 Nickel, . . Ni II 58.6 Antimony, . Sb III V 122 Niobium, Nb V 94 Arsenic, . . As III V 75 Nitrogen, N III V x4 Barium, . . Ba II 137 Norwegium, Ng 214 Beryllium, . Be II 9.4 Osmium, . . Os VI 198.6 Bismuth, . . Bi III V 208 Oxygen, . . 0 II 16 Boron, . . . B III 11 Palladium, . Pd II IV 106.5 Bromine, . . Br I 80 Phosphorus, P III V 31 Cadmium, Cd II 112 Platinum, . Pt IV 197.1 Caesium, . . Cs I *33 Potassium, . K I 39 Calcium, . . Ca II 40 Rhodium, . Rh II IV 104.3 Carbon, . . C IV 12 Rubidium, . Rb " I 854 Cerium, . , Ce II IV 140.5 Ruthenium,. Ru II IV 104.4 Chlorine, . . CI I 35-4 Samarium, . Sm III ■5° Chromium, . Cr IV 52.2 Scandium, . Sc III 44 Cobalt, . . . Co II 58.6 Selenium, . Se II IV VI 79-5 Copper, . . Cu II 63-5 Silicon, . . Si IV 28.2 Davyum, . . Da 154 Silver, . . . Ag I 108 Decipium, Dp III 159 Sodium, . . Na I 23 Didymium, . Di III V 146 Strontium, . Sr II 87.5 Erbium, . . Er in 163.9 Sulphur, . . S II IV VI 32 Fluorine, . . F i 19 Tantalum, . Ta III V 182 Gallium, . . Ga in 69 Tellurium, . Te II IV VI 128 Gold, . . . Au III V 196.7 Terbium, Tr 148.8 Hydrogen, . H I 1 Thallium, . Tl I III 204 Indium, . . In III "3-4 Thorium, Th II IV 23' -4 Iodine, . . . I I 127 Tin,. . . . Sn II IV 118 Iridium, . . Ir II IV 192 Titanium, . Ti IV 48 Iron, .... Fe II IV 56 Tungsten, . W IV 184 Lanthanum, . La III 138.5 Uranium, . U II 238-5 Lead, . . . Pb II 207 Vanadium, . V III V 5J-3 Lithium, . . Li I 7 Ytterbium, . Yb 1728 Magnesium, . Mg II 24 Yttrium, . . Y III 89-5 Manganese, . Mn II IV 55 Zinc, . . . Zn II 65-5 Mercury, . . Hg II 200 Zirconium, . Zr IV 90 Molybdenum, Mo II IV 96 13 INDEX. A PAGE "a"........................................ I3 Absolute alcohol.............................. 114 Acetamide....................................... 150 Acetanilide...................................... 151 Acetates.......................................... 118 Acetic acid...................................... 118 Acid................................. 16, 28, 30, in ------salts...................................... 31 Aconitine....................................... 153 Affinity chemical ............................ 11 Agate.............................................. 92 Air................................................. 71 Alabaster........................................ 56 Albumin....................................159, 176 Albuminoids.................................... 159 Alcohol.......................................... 113 Alcohols....................... 108, no, 114,117 Aldehydes .................................... 116 Alizarin......................................... 136 Alkalies.......................................... 38 Alkali, volatile................................. 73 Alkaline........................................ 30 Alkaloids........................................ 154 Allotropic....................................... 50 Alum........... .................................. 63 Alumina........,..... ........................... 63 Aluminum...................................... 63 Allyl............................................. 129 Amber..................................•......... 131 Amides........................................... 150 Amidogen....................................... 27 Amine........................................ 72,148 Ammonia....................................... 72 Ammonium ................................. 27, 72 ------substitutions.......................... 147 Amorphous phosphorus ................... 77 Amygdalin.................................. ... 145 Amy lose......................................... 140 Analysis......................................... 10 Anhydride..................................... 39 Anhydrous...................................... 39 Aniline..... ............................^......... 150 Anode............................................ 22 Anthracene...................................... 136 Antifebrin..................................... 151 Antimonic acid................................ 82 Antimony........................................ 81 Antimonyl.............................. ........ 27 Antipyretics................................... 154 Antipyrine....................................... 154 Antiseptics..................................... 98 Apomorphine................................... 152 Aqua ammonia.............................. 73 Aquafortis..................................... 74 PAGE Aqua regia..................................... 45 Arachidic acid...........................___ ng Argols............................................. I26 Arragonite....................................... 55 Arsenicum..................................... 79 Arsenic acid.................................... 81 Arsenous acid.................................. 79 Arsine............................................. 70 Ate................................................ i6 Atomic theory................................. n -----weights............................. 12,185 Atomicity........................................ ig Atoms............................................. n Atropine......................................... 153 Azurite............................................ 59 DAKING SODA......................... 41 *-^ Balsam................................... 130 Barium............................................ 57 Baryta............................................ 57 Barytes........................................... 57 Bases...................................29,49, 154 Basicity........................................... 31 Battery fluid................................... 69 Beers.............................................. 114 Beeswax......................................... 119 Behenic acid.................................... 119 Benzene......................................... 131 Benzoic acid.................................... 138 Benzoin.......................................... 138 Benzole........................................... 134 Benzyl............................................ 137 ■ aldehyde............................... 138 Bi.............................................. 16,24 Bin............................................... 14 Bile................................................ 169 Bile tests...................„.................... 175 Bilifuscin......................................... 169 Bilirubin......................................... 169 Biliverdin........................................ 169 Binary.......................................... 14 Bismuth.......................................... 84 Bivalent......................................... 19 Black lead....................................... 86 Bleaching powder..........................44>56 Blende........................................... 61 Blood............................................. 163 ------colors................................... 175 Bluestone....................................... 60 Blue vitriol...................................... 60 Boettger's test..........-..................84,179 Bone-ash......................................... 76 Bones............................................ 161 is: 188 INDEX. PAGE Boracic acid.......-........................... 70 Borax............................................. 70 Boric acid....................................... 70 Boron............................................. 70 Brain............................................. 162 Brandy.......................................... 114 Brass....................... .................... 59 Brimstone...................................... 50 Bromine.......................................... 46 Brucine........................................... 153 Butter............................................. 129 Butyric acid.................................... 120 CADMIUM................................. 62 Caesium................................... 42 Caffeine.......................................... 153 Calamine......................................... 61 Calcium.......................................... 55 Calculations................................... 34 Calculi............................................ 183 Calculus, mulberry........................... 125 Calomel......................................... 61 Camphor........................................ 131 Cane sugar..................................... 139 Caoutchouc.................................... 131 Capric acid...................................... 119 Caproic.......................................... 119 Caprylic acid................................... 119 Carat.............................................. 84 Carbolic acid................................... 136 Carbon............................................ 86 -----skeletons............................... 103 Carbonic acid.................................. 88 -----oxide.................................... 87 Carbonyl......................................... 27 Casein............................................. 160 Cassius' purple................................ 85 Cast iron......................................... 64 Caustic potassa............................... 40 -----soda..................................... 41 Celluloid......................................... 141 Cellulose......................................... 141 Cerebrin.......................................... 162 Cerotic acid..................................... ng Chalcedony..................................... 92 Chalk............................................. 55 Chalybeate waters........................... 66 Change, forms of............................. 9 Charcoal......................................... 86 Chemical affinity.............................. n -----change.................................. g Chili saltpetre.................................. 42 Chloral............................................ 117 Chlorates......................................... 46 Chloride of lime.............................. 56 Chlorides in urine............................ 175 Chlorine ......................................... 44 -----water.................................... 44 Chloroform...................................... 108 Chlorophyll .................................... 158 Cholesterol..................................... 160 Chondrin ........................................ 160 Chrome green.................................. 68 -----yellow................................... 69 PAGE Chromic acid................................... ^9 -----iron....................................... °9 Chromium....................................... 68 Chrysene......................................... X3S Chyle............................................ 164 Cinchonicine.................................... '52 Cinchonidine.................................. I52 Cinchonine...................................... 152 Cinnabar........................................ 61 Citric acid....................................... 126 Classification.............................. 10, 105 Coal............................................... 87 -----gas....................................... 87 Cobalt............................................ 69 Cocaine.......................................... 153 Codeine......................................... 152 Colchicine....................................... 153 Colostrum....................................... 166 Common salt................................... 42 Conine............................................ 152 Congo red....................................... 30 Corpuscles...................................... 163 Cohesion......................................... n Collodion....................................... 141 Combination.................................. 9, 17 -----by volume............................. 32 Copal............................................ 131 Copper.....................................■...... sg -----pyrites.................................. 59 Coppeias......................................... 66 Corrosive sublimate......................... 60 Corundum....................................... 63 Cream of tartar............................... 126 Cresol....................... ..................... 137 Cresylic acid.................................... 137 Crocus ...................... .................. 66 Cryolite............................'.............. 48 Crystallization, water of................... 39 Cyanic acid..................................... 147 Cyanides...................................... 144 Cyanogen................................... 27, 144 Cyanophyll..................................... 159 Cumene......................................... 134 Cymene......................................... 134 Cystine........................................... 183 T"\AVY'S LAMP......................... 90 *-* Decay............................. ..... 97 Decomposition................................ g Deliquescence................................ 62 Deut.............................................. 14 Dextrin.................................... ..... 140 Dextrose....................................... I40 Di.................................................. I4 Di-acid.......................................... 54 Di-acid base.................................... 3I Diamines........................................ l48 Diamond......................................... g- Diastase...........................„............ 1.0 Diatomic........................................] Ig ----- alcohols................................ I23 Dibasic........................................... ,x Digallicacid............................ ..... I4, Digestion................................,Z\Z 168 INDEX. 189 PAGE Doremus' apparatus......................... 181 Double salts................................... 31 Dutch liquid.................................... 123 Dyad............................................. 19 Dynamite..................................... 127 J?LECTRIC CALAMINE.......... 61 "^"' Electrical relations................... 23 Electro............................................ 22 Elements...............................g, 10, 185 Elceoptene..................................... 131 Emery............................................ 63 Empirical formula........................... 100 Epsom salt...................................... 62 Essences......................................... 130 Esters............................................. 108 Ethene............................................ 122 ------lactic acid............................. 124 Ether.....................•........................ 115 Ethers.............................. 108,109, JI^ Ethylates..................,..................... 116 Extractives..................................... 161 FAT-ACIDS............................... 119 Fats............ ........................... 128 Fehling's solution___........................ 180 Feldspar........................................ 64 Fermentation.................................. 97 Ferric salts...................................... 65 Ferricyanides.................................. 146 Ferrocyanides................................. 146 Ferrous salts.................................... 65 Fibrfti............................................. 160 Flame............................................. 89 ------tests..................................... 90 Flowers of sulphur........................... 50 Fluorine.......................................... 48 Fluorspar.................................. 48, 57 Fool's gold...................................... 66 Formic acid................................... 118 Formula..................................... 12, 21 Fusel oil.......................................... 114 GALENA................................... 58 *-* Gallic aid................................ 143 Gallo-tannic acid.............................. 143 Galvanized iron................................ 61 Gangue........................................... 57 Garlic, oil of.................................... 129 Gases, combination of....................... 32 Gastric juice.................................... 167 Gelatin............................................ 160 General formula.............................. 103 German silver.................................. 69 Glacial phosphoric acid............... 78, 177 Glass............................ ................. 64 ------, soluble................................. 92 Glauber's salt.................................. 42 Globulin.......................................... >59 Glucose........................................... M° Glucosides....................................... J42 Glycerin.......................................... "7 PAGE Glycerol.......................................... 127 Glycerophosphoric acid.................... 162 Glycocin........................................ 160 Glycocholic acid.............................. 160 Glycogen......................................... 142 Glycolic acid.................................... 123 Glycols........................................... 123 Graphic formulae.............................. 21 Graphite.......................................... 86 Green vitriol..................................... 66 Groups of elements..................... 10, 36 Gold.............................................. 84 Goulard's extract............................. 120 Gums.............................................. 141 Gum arabic.................................... 141 -----resin..................................... 130 -----tragacanth............................. 141 Gun-cotton...................................... 141 -----powder................................. 41 Gutta percha................................... 131 Gypsum......................................... 56 T-J^MATIN................................ 164 ,ti Haematite............................... 65 Haematocrystallin............................ 164 Haemin........................................... 164 Haemoglobin.................................... 164 Hard water................ .................... 56 Heller's test.................................... 177 Hexad........................................... 19 Hexatomic...................................... ig Hexivalent...................................... ig Hippuric acid.................................. 173 Homatropine................................... 153 Homologous.................................... 104 Humidity........................................ 72 Hyaenicacid................................... 119 Hydriodic acid................................ 47 Hydro acids.................................... 28 Hydrobromic acid............................ 47 Hydrocarbons................................ 106 Hydrochloric acid............................ 45 Hydrocyanic acid............................ 145 Hydrofluoric acid-....................•....... 48 Hydrogen................................... 28, 38 ^—^— dioxide................................. 40 Hydronaphthol................................ 136 Hydrosulphyl.................................. 27 Hydroquinone.............................. 135-7 Hydroxyl.......................................... 27 Hyoscyamine.................................. 153 Hyfier............................................. 16 Hypo............................................... 16 Hypochlorites............................ 46, 57 Hyposulphite................................ 54 Hypoxanthine................................. 159 yc........................................ 16,17,20 ■*■ Iceland spar.............................. 55 Ide................................................. 14 Indican........................................... 144 Indigo blue...................................... 144 Indigotin......................................... 144 190 INDEX. PAGE Ine................................................. 148 Inosite............................................ 158 Insolubility...................................... 24 Inverted sugar................................. 139 Iodine............................................. 47 Iodoform......................................... 108 Iron................................................ 64 Iron pyrites..................................... 66 Isologous......................................... 102 Isomerism....................................... 100 Isomorphous................................... 64 Ite................................................. 16 JASPER...................................... 92 Juice of flesh............................. 162 T^AOLIN.................................... 64 "■ Kathode................................. 22 Kephaline....................................... 162 Ketones......................................... 117 Kinetic theory................................. n King's yellow.................................. 81 Koumis.......................................... 166 Kreasote...........;............................. 137 Kreatinine....................................... 153 Kyner's test-glass............................ 177 T AC............................................ i3i J-/ Lactic acid.............................. 124 Lactose.......................................... 139 Laevulose........................................ 140 Lakmoid......................................... 31 Lampblack...................................... 86 Lard.............................................. 129 Laughing gas.................................. 76 Laurie acid...................................... ng Laws of chemistry........................... 17 Lead.............................................. 58 Lecithin.......................................... 162 Leucin............................................ 261 Leucomai'nes................................... 155 Libavius'_ liquor............................... 93 Lime......'......................................... 55 Limestone....................................... 55 Lime-water...................................... 55 Liquid silex..................................... g2 Liquor sanguinis............................ 163 Litharge.......................................... 58 Lithium......................................... 42 Litmus................................ 30, 137, 174 Loadstone....................................... 66 Lobeline......................................... 152 Lugol's solution............................... 47 Lunar caustic................................... 43 Lymph........................................... 165 1V/TAGNESIA.............................. 62 ■"■*■ Magnesite.............................. 62 Magnesium...................................... 62 Magnetic acid.................................. 66 Malachite........................................ 59 Malic acid...................................... 126 PAGE Malonic acid.................................... 123 Malt.............................................. 140 Manganese...................................... 67 Marble............................................ 55 Margaric acid................................ 119 Margarin........................................ 128 Marsh gas....................................... 107 Marsh's test................................... 80 Mass.............................................. 25 Massicot......................................... 58 Mead............................................. 114 Melissic acid................................... 119 Mercaptans.................................... 116 Mercury.......................................... 60 Meta............................................... 132 Metaboric acid.......... ..................... 70 Metaphosphoric acid...................... 78 Metamerism.................................... 100 Methanes................................. 107, in Methene......................................... 112 Methenyl ...................................... 127 Methyl........................................... 27 -----alcohol................................. 113 -----series.................................... 108 Milk.............................................. 165 —;---sugar.................................... 139 Mineral water.................................. 39 Minium.......................................... 58 Mixed salts.................................... 31 Molecular weight............................. 12 Molecules........................................ n Molybdenum................................... 94 Monad............................................ ™ Monamines.................................... 148 Monatomic....................................* ig -----alcohols................................ 113 Monivalent................................... ig Mono............................................. j^ Monobasic....................................... 31 Morphine........................................ j c;2 Monsel's solution.............................. 66 Mosaic gold.................................... g3 Mucin............................................. jyg Murexide test.................................. i76 Muscle............................................ 162 Muriatic acid................................... 45 Mustard......................................... z,, ------, oil of.................................. 130 Myeline.......................................... j62 Myristic acid.................................. 1Ig Myronic acid............................:.....'. 144 TVTAPHTHALENE.................. „* XN Naphthols............................ ^6 Narcotine........................... ' * Negative...........................!".'.."""".' 22 Nerve tissue.................................. Ifl2 Nessler's test...................."".!".".!"!!!!" Neurine............... '" Z Neutral.......................................... *°2 Nickel....................Z"'.'.'.'.'.'.'.'.'.'. '.'.'...... 6^ Nicotine............... ........... ,°^ Nitre......................."'.'.'.'.'.'.'.".'............. 53 Nitric acid..............■"".!!.'.'.".".!!.".'."' 74 191 PAGE Nitro-benzene............................ 75, 135 Nitro-compounds............................. 97 Nitrogen......................................... 71 Nitrogenous bodies.......................... 144 Nitro-glycerol............. .................... 127 Nitro-muriate of tin........................ 93 Nitrosyl......................................... 27 Nitrous acid.................................... 76 Nomenclature.......... ...................... 13 Nordhausen acid............................. 54 Normal salts................................... 31 Notation......................................... 12 ("PNANTHYLIC ACID........... 119 ^ ' ' Oil of bitter almonds............. 136 Oil of turpentine............................. 130 Oils, fixed...................................... 130 ------, essential............................... 130 ------, volatile................................ 130 Oleates............................................ 130 Olefins............................................ 122 Oleic acid........................................ 130 Oleo-resin....................................... 130 Onium............................................ 148 Orcin.............................................. 137 Organic bodies................................ 9s Organized bodies............................. 95 Orpiment........................................ 81 Ortho............................................. 132 Orthophosphoric acid....................... 78 Osmium......................................... 93 Ous ..................................... 16, 17, 20 Oxalates.................................. 125, 176 Oxalic acid...................................... 125 Oxidation...................................... 50 Oxidizing agents.............................. 50 Oxides............................................ 49 Oxybenzoic acid.............................. 138 Oxybutyric acid............................... 123 Oxygen........... .............................. 4Q -----acids..................................... 28 Oxy-salts......................................... 32 Ozone............................................. 50 PALMITIC ACID...................... 119 * Pancreatic extract.................... 169 Paraffine......................................... i°7 Paro............................................. 132 Paralactic acid.............................•■••• 124 Paraldehyde.................................... "7 Parchment paper............................. 141 Paris green..................................... 60 Pectin............................................. 158 Pectose...............---....................... 158 Pelargonic acid............................... "9 Pelletierine..................................... 153 Penta........... ................................. M Pentad............................................ J9 Pentatomic.................... ................. '9 Pentivalent..................................... *9 Pepsin........................................... l6° Peptones...... ........................... 160, 168 Per................................................ l6 PAGE Percentage composition...............34, 100 Permanganate................................. 68 Pewter........................................... 58 Phenacetin...................................... 155 Phenacetolin.................................... 31 Phenic acid.................................... 136 Phenol........................................... 136 Phenolphthalein........................».... 30 Phenyl............................................ 136 Phenylamine.................,................. 150 Phenylic alcohol.............................. 136 Phosphine...................................... 77 Phosphoric acid.............................. 78 Phosphorus..................................... 76 Physical change.............................. 9 Physostigmine................................. 153 Picric acid...................................... 137 Pig iron.......................................... 64 Pilocarpine................................... 153 Piperine... ...................................... 153 Plaster-of-Paris............................... 56 Platinum........................................ 93 Plumbago....................................... 86 Polymerism.................................... 100 Porcelain....................................... 64 Positive.......................................... 22 Potassium....................................... 40 Pottery........................................... 64 Proof spirit..................................... 114 Propenyl......................................... 127 Propionic acid................................ 119 Proteids.......................................... 159 Proto.............................................. 14 Proximate principles........................ 96 Prussian blue................................... 146 Prussiate of potash.......................... 146 Prussic acid.................................... 145 Ptomaines...................................... 156 Ptyalin............................................ 167 Pyrantimonic acid.......................... 82 Pyrocatechin.................................. 137 Pyridine.......................................... 15 * Pyrites........................................... 66 Pyrophosphoric acid........................ 78 Puce............................................... 58 Purple of Cassius............................. 85 Putrefaction.................................... 97 QUADRI.................................... 14 Quadrivalent........................... 19 Quartz............................................ 91 Quevenne's iron............................. 64 Quicklime....................................••• 55 Quinicine........................................ *52 Quinidine..................................'••••• *52 Quinine.......................................... 152 Quinoidine...................................... *52 Quinoline........................................ X51 Quinone......................................... *35 RADICLES....................... 21, 26, 31 Rational formulae..................... 100 Reactions...................................... 23 192 INDEX. PAGB Reagent.......................................... 22 Realgar.......................................... 81 Red lead......................................... 58 Red precipitate................................ 60 Reducing agents............................. 50 Reduction....................................... 50 ------test....................................... 80 ReinscW's test................................. 80 Residue........................................... 31 Resin............................................. 131 Resorcinol.................................... 137 Rex magnus................................... 70 Rochelle salt................................... 126 Rosaniline....................................... 151 Rosin............................................ 131 Rouge............................................. 66 Rubidium........................................ 42 Ruby............................................. 63 OACCHARIN............................. 138 ^ Salaeratus............................... 40 Sal ammoniac................................ 74 Salicin........................................... 143 Salicylic acid.............,.................... 138 Saliva............................................ 167 Salol............................................ 138 Sal soda......................................... 41 Salt, common................................... 42 -----of lemon............................... 125 ------of sorrel............................... 125 ------of tartar............................... 40 petre..................................... 40 ------spirit of................................ 45 Salts, forms of....................... 15, 30, 31 Sand............................................... 91 Sandarach ..................................... 131 Sapphire......................................... 63 Saturated ....................................... ig Scheele's green................................ 60 Schlippe's salt................................ 83 Schweinfurth green.......................... 60 Selenite......................................... 56 Selenium........................................ 55 Serum............................................ 163 Sesqui............................................ 15 Silicic acid..................................... 92 Silicon........................................... 91 Silver............................................ 43 Sinalbin.......................................... 144 Slag................................................ 64 Smelling salt................................... 74 Soaps ............................................ 127 Soapstone....................................... 62 Sodium........................................... 41 Stlaniri........................................... 143 Soldaini's test................................. I7g Solder............................................ 58 Soluble tartar.................................. 126 Sophorine....................................... 152 Specific gravity of urine................... 174 Specular iron.................................. 66 Speculum metal............................... 92 Spermaceti...................................... 129 Spirit of Mindererus......................... 118 PAGE Spirit of nitre................................. JI^ ------salt...................................... 45 ------turpentine............................. I3° ------wine..................................... 113 Stalactite........................................ 56 Stalagmite..................................... 56 Starch........................................... 140 Starches.......................................... 140 Stearic acid..................................... 120 Siearoptene..................................... 131 Steel.............................................. 65 Stibine............................................ 82 Stibium.......................................... 81 Strontium....................................... 58 Strychnine...................................... 152 Sub.......................................... ..... 14 Sublimation test.............................. 80 Substitution.................................... 98 Succinic acid................................... 125 Sucrose.......................................... 139 Sugar in urine................................. 178 ------of lead................................. 120 Sugars .......................................... 139 Sulphates........................................ 54 Sulphocyanates .............................. 147 Sulph............................................. 51 Sulphur.......................................... 50 ------alcohols................................ 116 ------salts...................................... 51 Sulphuric acid ................................ 53 Sulphurous acid......... .................... 52 Sweat............................................. 171 Symbols..................................... 12, 185 Synaptase........................................ 144 Synthesis................................... 10, 100 'pALC.......................................... 62 ■*■ Tannin................................... 143 Tartar..................................... 126, 167 ------emetic..... ........................... 82 ------salt of................................... 40 Tartaric acid................................... 126 Tauiin.......................................... 160 Taurocholic acid............................ 160 Teeth............................................ 161 Tellurium....................................... 55 Ter................................................ 14 Test-papers..................................... 175 Tetanine......................................... 156 Tetra.:........................................... 14 Tetrabasic...................................... 31 Tetrad........................................... 19 Tetramines...................................... 148 Tetratomic...................................... ig Theobromine.................................. 153 Theine............................................ ^3 Thio............................................... 5I Thiosulphuric acid.......................... 54 Tin...............................................'. IOI —— Plate..................................... 92 Toluene.......................................... j,e Toluidine........................................ ,„ Tri.........................................'..""'. 14 Triad.........................................\\\\ lg 193 PAGE Triamines...................................... 148 Triatomic...................................... 19 Tribasic......................................... 31 Trichloracetic acid........................... 108 Trinitro-phenol............................... 137 Tritenyl........................................ 127 Trivalent........................................ ig Trommer's test............................... 178 Trypsin......................................... 171 Turpenes........................................ 130 Turpentine...................................... 130 Turpeth mineral.............................. 60 Type metal..................................... 58 Tyrosin.......................................... 161 Tyrotoxicon................................... 156 TJM............................................ 13 *-' Unsaturated ..... ................... 21 Urea........................................ 173, 180 Uric acid........................................ 173 Urinary calculi................................ 183 -----deposits............................... 183 Ultimate analysis............................ 96 Urine............................................. 172 Urinometer..................................... 174 Urobilin.......................................... 175 ■yALENCY............................ 18, 185 * Valeric acid............................. 120 Vallet's mass.................................. 66 Vanadium....................................... 85 Vapor density................................. 102 Vegetable chemistry....................... 157 Venetian red................................... 66 Veratrine........................................ 153 Verdigris........................................ 120 Vermilion....................................... 61 PAGE Vinic acids................................... 109 Vitellin........................................... 159 Vitriol, blue.................................... 60 -----green................................... 66 -----°'l......................................... 53 -----white.................................... 62 Volatile alkali................................ 73 Volatility...................................2.. 25 Volume combination........................ 32 Vulcanizing.................................... 51 WASHING SODA................... 41 Water.................................. 36 -----crystallization....................... 39 -----gas....................................... 87 -----, oxygenated.......................... 40 Waters, natural............................... 39 Waxes.......................................... 129 Whiskey......................................... 114 White arsenic.................................. 79 -----lead...................................... 58 -----vitriol.....'.............................. 62 Wines............................................. 114 Witherite........................................ 57 Wood spirit.................................... 113 Wrought iron.................................. 65 VANTHINE........................ 153, 170 ■**■ Xanthophyll........................... 159 Xylene........................................... 134 rTTRIUM . 86 7INC........................................... 61 ^ -----white............................ 61 JUST PUBLISHED. A NEW Medical Dictionary, GEORGE M. GOULD, A.B., M.D., JS OPHTHALMIC SURGEON TO THE PHILADELPHIA HOSPITAL, CLINICAL CHIEF a "•"' OPHTHALMOLOGICAL DEPT. GERMAN HOSPITAL, PHILADELPHIA. £ 2 A compact, concise Vocabulary, including all the 3 H Words and Phrases used in medicine, with their proper "^ Pronunciation and Definitions, |- BASED ON RECENT MEDICAL LITERATURE. | It is not a mere compilation from other dictionaries. * The definitions have been made by the aid of the most ^ recent standard text-books in the various branches of § medicine, and it will therefore meet the wants of every §• physician and student. It includes a SEVERAL THOUSAND WORDS NOT CON- | TA1NED IN ANY SIMILAR WORK. | It is printed on handsome paper, made especially for §. the purpose ; from a new type selected on account of its a clear, distinct face, and is bound so that it will lie open ^ at any page. £ 8 Small Octavo, 520 Pages, Half-Dark Leather, $3.25. * With Thumb Index, Half Morocco, Marbled Edges, $4.25. ■; It may be obtained through Booksellers, Wholesale Druggists and Dental Depots everywhere. [over] Gould's New Medical Dictionary. There has been no dictionary accessible to the physician and student that has kept pace with the coinage of new words and terms during the past ten years. The growth of specialism in itself has increased the vocabulary by some thousands of words; and yet the busy practitioner or student has been offered no com- pact, thorough dictionary to which he could turn for a definition absolutely necessary to the proper understanding of the article he might be reading. This expressed want has led to the preparation of this work. The aim has been to prepare a handbook of sufficient scope to include everything of use to the general practitioner and student, and at the same time to be a compact, handy volume, giving the exact information desired at a quick reference. The wants of the specialist have also been taken into consideration, and the seeker after more extended knowledge will find much precise information relating to his special branch, to the etymology and meaning of words, etc. IT CONTAINS TABLES " i. Of the ABBREVIATIONS used in Medicine, Prefixes and Suffixes of Medical Words, etc. 2. Of the ARTERIES, with the Name, Origin, Distribution and Branches of each. 3. Of the BACILLI, giving the Name, Habitat, Characteristics of the Cultures (upon slides, gelatin, gelose, potato and bouillon). De- scription of the Cellules, the Influence of Oxygen and Heat, the Physiological Action, and Sundry Observations. 4. Of GANGLIA, with the Name, Location, Roots and Distribution of each. 5. Of LEUCOMAINES, giving the Name, Formula, Discoverer, Source and Physiological Action. 6. Of MICROCOCCI, giving the same information as in the case of the Bacilli. 7. Of MUSCLES, with the Name, Origin, Insertion, Innervation and Function. 8. Of NERVES, with the Name, Function, Origin, Distribution and Branches. 9. Of PLEXUSES.with the Name, Location, Derivation and Distribution. 10. Of PTOMAINES, with the Name, Formula, Discoverer, Source and Physiological Action. 11. Of COMPARISON OF THERMOMETERS ; of all the most used WEIGHTS AND MEASURES of the world; of the MINERAL SPRINGS OF THE U. S., VITAL STATISTICS, etc., etc. Some of the material thus classified is not obtainable by Eng- lish readers in any other work. [over] CATALOGUE No. 7. FEBRUARY, 1891. A CATALOGUE OF Books for Students. INCLUDING THE ? QUIZ-COMPENDS ? CONTENTS. PAGE New Series of Manuals, 2,3,4, s Anatomy, 6 Biology, 11 Chemistry, . 6 Children's Diseases, 7 Dentistry, 8 Dictionaries, 8 Eye Diseases, q Electricity, . q Gynaecology, 10 Hygiene, q Materia Medica, . q Medical Jurisprudence, 10 PUBLISHED BY P. BLAKISTON, SON & CO., Medical Booksellers, Importers and Publishers. LARGE STOCK OF ALL STUDENTS' BOOKS, AT THE LOWEST PRICES. 1012 Walnut Street, Philadelphia. *** For sale by all Booksellers, or any book will be sent by mail, postpaid, upon receipt of price. Catalogues of books on all branches of Medicine, Dentistry, Pharmacy, etc., supplied upon application. ■8E5- Gould's New Medical Dictionary Just Ready. Seepage lb. Obstetrics. . Pathology, Histology, Pharmacy, . Physiology, . Practice of Medicine, Prescription Books, PQuiz-Compends ? . 14 Skin Diseases, Surgery, Therapeutics, Urine and Urinary Organs, Venereal Diseases, "An excellent Series of Manuals."—Archives of Gynacology. A NEW SERIES OF STUDENTS' MANUALS On the various Branches of Medicine and Surgery. Can be used by Students of any College. Price of each, Handsome Cloth, $3.00. Full Leather, $3.50. The object of this series is to furnish good manuals for the medical student, that will strike the medium between the compend on one hand and the prolix text- book on the other—to contain all that is necessary for the student, without embarrassing him with a flood of theory and involved statements. They have been pre- pared by well known men, who have had large experience as teachers and writers, and who are, therefore, well informed as to the needs of the student. Their mechanical execution is of the best—good type and paper, handsomely illustrated whenever illustrations are of use, and strongly bound in uniform style. Each book is sold separately at a remarkably low price, and the immediate success of several of the volumes shows that the series has met with popular favor. No. 1. SURGERY. 236 Illustrations. A Manual of the Practice of Surgery. By Wm. J. Walsham, m.d., Asst. Surg, to, and Demonstrator of Surg, in, St. Bartholomew's Hospital, London, etc. 228 Illustrations. Presents the introductory facts in Surgery in clear, precise language, and contains all the latest advances in Pathology, Antiseptics, etc. " It aims to occupy a position midway between the pretentious manual and the cumbersome System of Surgery, and its general character may be summed up in one word—practical."—The Medi- cal Bulletin. " Walsham, besides being an excellent surgeon, is a teacher in its best sense, and having had very great experience in the preparation of candidates for examination, and their subsequent professional career, may be relied upon to have carried out his work successfully. Without following out in detail his arrange- ment, which is excellent, we can at once say that his book is an embodiment of modern ideas neatly strung together, with an amount of careful organization well suited to the candidate, and, indeed to the practitioner."—British Medical Journal. Price of each Book, Cloth, $3.00; Leather, $3.60. THE NEW SERIES OF MANUALS. S No. 2. DISEASES OF WOMEN. 150 Illus. Nh.W EDITION. The Diseases of Women. Including Diseases of the Bladder and Urethra. By Dr. F. Winckel, Professor of Gynaecology and Director of the Royal University Clinic for Women, in Munich. Second Edition. Re- vised and Edited by Theophilus Parvin, M.D., Professor of Obstetrics and Diseases of Women and Children in Jefferson Medical College. 150 Engrav- ings, most of which are original. " The book will be a valuable one to physicians, and a safe and satisfactory one to put into the hands of students. It is issued in a neat and attractive form, and at a very reasonable price."—Boston Medical and Surgical Journal. No. 3. OBSTETRICS. 227 Illustrations. A Manual of Midwifery. By Alfred Lewis Galabin, M.A., M.D., Obstetric Physician and Lecturer on Mid- wifery and the Diseases of Women at Guy's Hospital, London; Examiner in Midwifery to the Conjoint Examining Board of England, etc. With 227 Illus. " This manual is one we can strongly recommend to all who desire to study the science as well as the practice of midwifery. Students at the present time not only are expected to know the principles of diagnosis, and the treatment of the various emergen- cies and complications that occur in the practice of midwifery, but find that the tendency is for examiners to ask more questions relating to the science of the subject than was the custom a few years ago * * * The general standard of the manual is high; and wherever the science and practice of midwifery are well taught it will be regarded as one of the most important text-books on the subject."—London Practitioner. No. 4. PHYSIOLOGY. Fourth Edition. 321 ILLUSTRATIONS AND A GLOSSARY. A Manual of Physiology. By Gerald F. Yeo, m.d., F.R.C S., Professor of Physiology in King's College, London. 321 Illustrations and a Glossary of Terms. Fourth American from second English Edition, revised and improved. 758 pages. This volume was specially prepared to furnish students with a new text-book of Physiology, elementary so far as to avoid theories which have not borne the test of time and such details of methods as are unnecessary for students in our medical colleges. " The brief examination I have given it was so favorable that I placed it in the list of text-books recommended in the circular of the University Medical College."—Prof. Lewis A. Stimson., m.d., 37 East 33d Street, New York. Price of each Book, Cloth, $3.00; Leather, $3.50. 4 THE NEW SERIES OF MANUALS. No. 5. DISEASES OF CHILDREN. SECOND EDITION. A Manual. By J. F. Goodhart, m.d., Phys. to the Evelina Hospital for Children; Asst. Phys. to Guy's Hospital, London. Second American Edition. Edited and Rearranged by Louis Starr, m.d., Clinical Prof, of Dis. of Children in the Hospital of the Univ. of Pennsylvania, and Physician to the Children's Hos- pital, Phila. Containing many new Prescriptions, a list of over 50 Formulae, conforming to the U. S. Pharma- copoeia, and Directions for making Artificial Human Milk, for the Artificial Digestion of Milk, etc. Illus. " The merits of the book are many. Aside from the praiseworthy work of the printer and binder, which gives us a print and page that delights the eye, there is the added charm of a style of writ- ing that is not wearisome, that makes its statements clearly and forcibly, and that knows when to stop when it has said enough. The insertion of typical temperature charts certainly enhances the value of the book. It is rare, too, to find in any text-book so many topics treated of. All the rarer and out-of-the-way diseases are given consideration. This we commend. It makes the work valuable."—Archives of Pedriatics, July, i8qo. " The author has avoided the not uncommon error of writing a book on general medicine and labeling it ' Diseases of Children,' but has steadily kept in view the diseases which seemed to be incidental to childhood, or such points in disease as appear to be so peculiar to or pronounced in children as to justify insistence upon them. * * * A safe and reliable guide, and in many ways admirably adapted to the wants of the student and practitioner."— American Journal of Medical Science. " Thoroughly individual, original and earnest, the work evi- dently of a close observer and an independent thinker, this book, though small, as a handbook or compendium is by no means made up of bare outlines or standard facts."—The Therapeutic Ga- zette. " As it is said of some men, so it might be said of some books, that they are ' born to greatness.' This new volume has, we believe, a mission, particularly in the hands of the younger members of the profession. In these days of prolixity in medical literature, it is refreshing to meet with an author who knows both what to say and when he has said it. The work of Dr. Goodhart (admirably conformed, by Dr. Starr, to meet American require- ments) is the nearest approach to clinical teaching without the actual presence of clinical material that we have yet seen."—New York Medical Record. Price of each Book, Cloth, $3.00 ; Leather, $3.50. THE NEW SERIES OF MANUALS. 5 No. 6. PRACTICAL THERAPEUTICS. FOURTH EDITION, WITH AN INDEX OF DISEASES. Practical Therapeutics, considered with reference to Articles of the Materia Medica. Containing, also, an Index of Diseases, with a list of the Medicines applicable as Remedies. By Edward John Waring, M.D., F.R.c.P. Fourth Edition. Rewritten and Re- vised by Dudley W. Buxton, m.d., Asst. to the Prof. of Medicine at University College Hospital. " We wish a copy could be put in the hands of every Student or Practitioner in the country. In our estimation, it is the best book of the kind ever written."—N. Y. Medical Journal. " Dr. Waring's Therapeutics has long been known as one of the most thorough and valuable of medical works. The amount of actual intellectual labor it represents is immense. . . . An in- dex of diseases, with the remedies appropriate for their treatment, closes the volume."—Boston Medical and Surgical Reporter. " The plan of this work is an admirable one, and one well calcu- lated to meet the wants of busy practitioners. There is a remark- able amount of information, accompanied with judicious comments, imparted in a concise yet agreeable style."—Medical Record. No. 7. MEDICAL JURISPRUDENCE AND TOXICOLOGY. NEW, REVISED AND ENLARGED EDITION. By John J. Reese, m.d., Professor of Medical Jurispru- dence and Toxicology in the University of Pennsyl- vania; President of the Medical Jurisprudence Society of Phila.; 2d Edition, Revised and Enlarged. "This admirable text-book."—Amer.Jour. of Med. Sciences. " We lay this volume aside, after a careful perusal of its pages, with the profound impression that it should be in the hands of every doctor and lawyer. It fully meets the wants of all students..... He has succeeded in admirably condensing into a handy volume all the essential points."—Cincinnati Lancet and Clinic. " The book before us will, we think, be found to answer the ex- pectations of the student or practitioner seeking a manual of juris- prudence, and the call for a second edition is a nattering testimony to the value of the author's present effort. The medical portion of this volume seems to be uniformly excellent, leaving little for adverse criticism. The information on the subject matter treated has been carefully compiled, in accordance with recent knowledge. The toxicological portion appears specially excellent Of that por- tion of the work treating of the legal relations of the practitioner and medical witness, we can express a generally favorable ver- dict."— Physician and Surgeon, Ann Arbor, Mich. Price of each Book, Cloth, $3,00; Leather, $3.50. 6 STUDENTS' TEXT-BOOKS AND MANUALS. ANATOMY. Macalister's Human Anatomy. 816 Illustrations. A new Text-book for Students and Practitioners-, Systematic and Topo- graphical, including the Embryology, Histology and Morphology of Man. With special reference to the requirements of Practical Surgery and Medicine. With 816 Illustrations, 400 of which are original. Octavo. Cloth, 7.50; Leather, 8.50 Ballou's Veterinary Anatomy and Physiology. Illustrated. By Wm. R. Ballon, m.d., Professor of Equine Anatomy at New York College of Veterinary Surgeons. 29 graphic Illustrations. i2mo. Cloth, 1.00; Interleaved for notes, 1.25 Holden's Anatomy. A manual of Dissection of the Human Body. Fifth Edition. Enlarged, with Marginal References and over 200 Illustrations. Octavo. Cloth, 5.00; Leather, 6.00 Bound in Oilcloth, for the Dissecting Room, $4.50. " No student of Anatomy can take up this book without being pleased and instructed. Its Diagrams are original, striking and suggestive, giving more at a glance than pages of text description. * * * The text matches the illustrations in directness of prac- tical application and clearness of detail."—New York Medical Record. Holden's Human Osteology. Comprising a Description of the Bones, with Colored Delineations of the Attachments of the Muscles. The General and Microscopical Structure of Bone and its Development. With Lithographic Plates and Numerous Illus- trations. Seventh Edition. 8vo. Cloth, 6.00 Holden's Landmarks, Medical and Surgical. 4th ed. Clo., 1.25 Heath's Practical Anatomy. Sixth London Edition. 24 Col- ored Plates, and nearly 300 other Illustrations. Cloth, 5.00 Potter's Compend of Anatomy. Fifth Edition. Enlarged. 16 Lithographic Plates. 117 Illustrations. Cloth, 1.00; Interleaved for Notes, 1.25 CHEMISTRY. Bartley's Medical Chemistry. Second Edition. A text-book prepared specially for Medical, Pharmaceutical and Dental Stu- dents. With 50 Illustrations, Plate of Absorption Spectra and Glossary of Chemical Terms. Revised and Enlarged. Cloth, 2.50 Trimble. Practical and Analytical Chemistry. A Course in Chemical Analysis, by Henry Trimble, Prof, of Analytical Chem- istry in the Phila. College of Pharmacy. Illustrated. Third Edition. 8vo. Cloth, 1.50 *&- See pages 2 to 5 for list of Students' Manuals. STUDENTS' TEXT-BOOKS AND MANUALS. 7 Chemistry :—Continued. Blo.xam's Chemistry, Inorganic and Organic, with Experiments. Seventh Edition. Enlarged and Rewritten. 330 Illustrations. Cloth, 4.50; Leather, 5.50 Richter's Inorganic Chemistry. A text-book for Students. Third American, from Fifth German Edition. Translated by Prof. Edgar F. Smith, ph.d. 89 Wood Engravings and Colored Plate of Spectra. Cloth, 2.00 Richter's Organic Chemistry, or Chemistry of the Carbon Compounds. Illustrated. Cloth, 3.00; Leather, 3.50 Symonds. Manual of Chemistry, for the special use of Medi- cal Students. By Brandreth Symonds, a.m., m.d., Asst. Physician Roosevelt Hospital, Out-Patient Department; Attend- ing Physician Northwestern Dispensary, New York. i2mo. Cloth, 2.00; Interleaved for Notes, 2.40 Tidy. Modern Chemistry. 2d Ed. Cloth, 5.50 Leffmann's Compend of Chemistry. Inorganic and Organic. Including Urinary Analysis. Third Edition. Revised. Cloth, 1.00; Interleaved for Notes, 1.25 Leffmann and Beam. Progressive Exercises in Practical Chemistry. i2mo. Illustrated. Cloth, 1.00 Muter. Practical and Analytical Chemistry. Second Edi- tion. Revised and Illustrated. Cloth, 2.00 Holland. The Urine, Common Poisons, and Milk Analysis, Chemical and Microscopical. For Laboratory Use. 3d Edition, Enlarged. Illustrated. Cloth, 1.00 Van Nvvr., urine Analysis. Illus. Cloth, 2.00 Wolff's Applied Medical Chemistry. By Lawrence Wolff, m.d., Dem. of Chemistry in Jefferson Medical College. Clo., 1.00 CHILDREN. Goodhart and Starr. The Diseases of Children. Second Edition. By J. F. Goodhart, m.d., Physician to the Evelina Hospital for Children; Assistant Physician to Guy's Hospital, London. Revised and Edited by Louis Starr, m.d., Clinical Professor of Diseases of Children in the Hospital of the Univer- sity of Pennsylvania; Physician to the Children's Hospital, Philadelphia. Containing many Prescriptions and Formula:, conforming to the U. S. Pharmacopoeia, Directions for making Artificial Human Milk, for the Artificial Digestion of Milk, etc. Illustrated. Cloth, 3.00; Leather, 3.50 Hatfield. Diseases of Children. By M. P. Hatfield, m d. , Professor of Diseases of Children, Chicago Medical College. Colored Plate. i2mo. Cloth, 1.00; Interleaved, 1.25 Day. On Children. A Practical and Systematic Treatise. Second Edition. 8vo. 752 pages. Cloth, 3.00; Leather, 4.00 0&- See pages 14 and IS for list of t Quiz- Compends t 8 STUDENTS' TEXT-BOOKS AND MANUALS. Children:—Continued. Meigs and Pepper. The Diseases of Children. Seventh Edition. 8vo. Cloth, 5.00; Leather, 6.00 Starr. Diseases of the Digestive Organs in Infancy and Childhood. With chapters on the Investigation of Disease, and on the General Management of Children. By Louis Starr, m.d., Clinical Professor of Diseases of Children in the Univer- sity of Pennsylvania. Illus. Second Edition. Cloth, 2.25 DENTISTRY. Fillebrown. Operative Dentistry. 330 Illus. Cloth, 2.50 Flagg's Plastics and Plastic Filling. 3d Ed. Preparing. Gorgas. Dental Medicine. A Manual of Materia Medica and Therapeutics. Third Edition. , Cloth, 3.50 Harris. Principles and Practice of Dentistry. Including Anatomy, Physiology, Pathology, Therapeutics, Dental Surgery and Mechanism. Twelfth Edition. Revised and enlarged by Professor Gorgas. 1028 Illustrations. Cloth, 7.00 ; Leather, 8.00 Richardson's Mechanical Dentistry. Fifth Edition. 569 Illustrations. 8vo. Cloth, 4.50; Leather, 5.50 Sewill. Dental Surgery. 200 Illustrations. 3d Ed. Clo., 3.00 Stocken's Dental Materia Medica. Third Edition. Cloth, 2.50 Taft's Operative Dentistry. Dental Students and Practitioners. Fourth Edition. 100 Illustrations. Cloth, 4.25 ; Leather, 5.00 Talbot. Irregularities of the Teeth, and their Treatment. Illustrated. 8vo. Second Edition. Cloth, 3.00 Tomes' Dental Anatomy. Third Ed. 191 Illus. Cloth, 4.00 Tomes' Dental Surgery. 3d Edition. Revised. 292 Illus. 772 Pages. . Cloth, 5.00 Warren. Compend of Dental Pathology and Dental Medi- cine. Illustrated. Cloth, 1.00; Interleaved, 1.25 DICTIONARIES. Gould's New Medical Dictionary. Containing the Definition and Pronunciation of all words in Medicine, with many useful ?5Tables etc. yi. Dark Leather, 3.25; J^ Mor., Thumb Index 4.25 Cleaveland's Pronouncing Pocket Medical Lexicon. 31st ^Edition. Giving correct Pronunciation and Definition. Very small pocket size. Cloth, red edges .7s ; pocket-book style, 1.00 Longley's Pocket Dictionary. The Student's Medical Lexicon, giving Definition and Pronunciation of all Terms used in Medi- cine, with an Appendix giving Poisons and Their Antidotes, Abbreviations used in Prescriptions, Metric Scale of Doses, etc. 24mo. Cloth, 1.00; pocket-book style, 1.23 $9=See pages 2 to 5 for list of Students' Manuals. STUDENTS' TEXT-BOOKS AND MANUALS. 9 EYE. Arlt. Diseases of the Eye. Including those of the Conjunc- tiva, Cornea, Sclerotic, Iris and Ciliary Body. By Prof. Von Arlt. Translated by Dr. Lyman Ware. Illus. 8vo. Cloth, 2.50 Hartridge on Refraction. 4th Ed. Cloth, 2.00 Meyer. Diseases of the Eye. A complete Manual for Stu- dents and Physicians. 270 Illustrations and two Colored Plates. 8vo. Cloth, 4.50; Leather, 5.30 Fox and Gould. Compend of Diseases of the Eye and Refraction. 2d Ed. Enlarged. 71 Illus. 39 Formulae. Cloth, 1.00 ; Interleaved for Notes, 1.25 ELECTRICITY. Mason's Compend of Medical and Surgical Electricity. With numerous Illustrations. i2mo. Cloth, 1.00 HYGIENE. Parkes' (Ed. A.) Practical Hygiene. Seventh Edition, en- larged. Illustrated. 8vo. Cloth, 4.50 Parkes' (L. C.) Manual of Hygiene and Public Health, Second Edition. i2mo. Cloth, 2.50 Wilson's Handbook of Hygiene and Sanitary Science. Seventh Edition. Revised and Illustrated. In Press. MATERIA MEDICA AND THERAPEUTICS. Potter's Compend of Materia Medica, Therapeutics and Prescription Writing. Fifth Edition, revised and improved. Cloth, 1.00; Interleaved for Notes, 1.25 Biddle's Materia Medica. Eleventh Edition. By the late John B. Biddle, m.d., Professor of Materia Medica in Jefferson Medical College, Philadelphia. Revised, and rewritten, by Clement Biddle, m.d., Assist. Surgeon, U. S. N., assisted by Henry Morris, m.d. 8vo.,illustrated. Cloth, 4.25; Leather, 5.00 Headland's Action of Medicines. 9th Ed. 8vo. Cloth, 3.00 Potter. Materia Medica, Pharmacy and Therapeutics. Including Action of Medicines, Special Therapeutics, Pharma- cology, etc. Second Edition. - Cloth, 4.00; Leather, 5.00 Starr, Walker and Powell. Synopsis of Physiological Action of Medicines,based upon Prof. H. C. Wood's " Materia Medica and Therapeutics." 3d Ed. Enlarged. Cloth, .75 Waring. Therapeutics. With an Index of Diseases and Remedies. 4th Edition. Revised. Cloth, 3.00; Leather, 3.50 *S- See pages 14 and ij for list of t Quiz- Compends f 10 STUDENTS' TEXT-BOOKS AND MANUALS. MEDICAL JURISPRUDENCE. Reese. A Text-book of Medical Jurisprudence and Toxi- cology. By John J. Reese, m.d., Professor of Medical Juris- prudence and Toxicology in the Medical Department of the University of Pennsylvania, President of the Medical Juris- prudence Society of Philadelphia; Physician to St. Joseph's Hospital; Corresponding Member of The New York Medico- legal Society. 2d Edition. Cloth, 3.00; Leather, 3.50 Woodman and Tidy's Medical Jurisprudence and Toxi- cology. Chromo-Lithographic Plates and 116 Wood engravings. Cloth, 7.50 ; Leather, 8.50 OBSTETRICS AND GYNECOLOGY. Byford. Diseases of Women. The Practice of Medicine and Surgery, as applied to the Diseases and Accidents Incident to Women. By W. H. Byford, a.m., m.d, Professor of Gynaecology in Ru>h Medical College and of Obstetrics in the Woman's Med- ical C ;age, etc., and Henry T. Byford, m.d., Surgeon to the Woman's Hospital of Chicago ; Gynaecologist to St Luke's Hospital, etc. Fourth Edition. Revised, Rewritten and En- larged. With 306 Illustrations, over 100 of which are original. Octavo. 832 pages. Cloth, 5.00 ; Leather, 6.00 Cazeaux and Tarnier's Midwifery. With Appendix, by Munde. The Theory and Practice of Obstetrics ; including the Diseases of Pregnancy and Parturition, Obstetrical Operations, etc. By P. Cazeaux. Remodeled and rearranged, with revi- sions and additions, by S. Tarnier, m.d , Professor of Obstetrics and Diseases of Women and Children in the Faculty of Medicine of Paris. Eighth American, from the Eighth French and First Italian Edition. Edited by Robert J. Hess, m.d., Physician to the Northern Dispensary, Philadelphia, with an appendix by Paul F. Munde, m.d., Professor of Gynaecology at the N. Y. Polyclinic. Illustrated by Chromo-Lithographs, Lithographs, and other Full-page Plates, seven of which are beautifully colored, and numerous Wood Engravings. Students' Edition. One Vol., 8vo Cloth, 5.00; Leather, 6.00 Lewers' Diseases of 'Women. A Practical Text-Book. 139 Illustrations. Second Edition. Cloth, 2.50 Parvin's Winckel's Diseases of'Women. Second Edition. Including a Section on Diseases of the Bladder and Urethra. 150 Illus. Revised. See page 3. Cloth, 3.00; Leather, 3.50 Morris. Compend of Gynaecology. Illustrated. Cloth, 1.00 Winckel's Obstetrics. A Text-book on Midwifery, includ- ing the Diseases of Childbed. By Dr. F. Winckel, Professor of Gynaecology, and Director of the Royal University Clinic for Women, in Munich. Authorized Translation, by J. Clifton Edgar, m.d., Lecturer on Obstetrics, University Medical Col- lege, New York, with nearly 200 handsome illustrations, the majority of which are original with this work. Octavo. Cloth, 6.00 ; Leather, 7.00 Landis' Compend of Obstetrics. Illustrated. 4th edition, enlarged. Cloth, 1.00; Interleaved for Notes, 1.25 49" See pages 2 to 5 for list of New Manuals. STUDENTS' TEXT-BOOKS AND MANUALS. 11 Obstetrics and Gyna-cology :—Continued. Galabin's Midwifery. By A. Lewis Galabin, m.d., f.r.c.p. 227 Illustrations. See page 3. Cloth, 3.00; Leather, 3.50 Glisan's Modern Midwifery. 2d Edition. Cloth, 3.00 Rigby's Obstetric Memoranda. 4th Edition. Cloth, .50 Meadows' Manual of Midwifery. Including the Signs and Symptoms of Pregnancy, Obstetric Operations, Diseases of the Puerperal State, etc. 145 Illustrations. 494 pages. Cloth, 2.00 Swayne's Obstetric Aphorisms. For the use of Students commencing Midwifery Practice. 8th Ed. i2mo. Cloth, 1.25 PATHOLOGY. HISTOLOGY. BIOLOGY. . Bowlby. Surgical Pathology and Morbid Anatomy, for Students. 135 Illustrations. i2mo. Cloth, 2.00- Davis* Elementary Biology. Illustrated. Cloth, 4.00 Gilliam's Essentials of Pathology. A Handbook for Students. 47 Illustrations, ismo. Cloth, 2.00 *#* The object of this book is to unfold to the beginner the funda- mentals of pathology, in a plain, practical way, and by bringing them within easy comprehension to increase his interest in the study of the subject. Gibbes' Practical Histology and Pathology. Third Edition. Enlarged. 12 mo. Cloth, 1.75 Virchow's Post-Mortem Examinations. 2d Ed. Cloth, 1.00 PHYSIOLOGY. Yeo's Physiology. Fourth Edition. The most Popular Stu- dents' Book. By Gerald F Yeo, m.d., f.r.c.s., Professor of Physiology ir. Kind's College, London. Small Octavo. 758 pages. ^321 carefully printed Illustrations. With a Full Glossary and Index. See Page 3. Cloth, 3.00; Leather, 3.50 Brubaker's Compend of Physiology. Illustrated. Fifth Edition. Cloth, 1.00; Interleaved for Notes, 1.25 Stirling. Practical Physiology, including Chemical and Ex- perimental Physiology. 142 Illustrations. Cloth, 2.25 Kirke's Physiology. New 12th Ed. Thoroughly Revised and Enlarged. 502 Illustrations. Cloth, 4.00; Leather, 5.00 Landois' Human Physiology. Including Histology and Micro- scopical Anatomy, and with special reference to Practical Medi- cine. Third Edition. Translated and Edited by Prof. Stirling. 692 Illustrations. Cloth, 6.50; Leather, 7.50^ " With this Text-book at his command, no student could fail in his examination."—Lancet. Sanderson's Physiological Laboratory. Being Practical Ex- ercises for the Student. 350 Illustrations. 8vo. Cloth, 5.00 Tvson's Cell Doctrine. Its History and Present State. Illus- trated. Second Edition. Cloth, 2.0a 99-See pages 14 and IS for list of f Quiz-Compends t 12 STUDENTS' TEXT-BOOKS AND MANUALS. PRACTICE. Taylor. Practice of Medicine. A Manual. By Frederick Taylor, m.d., Physician to, and Lecturer on Medicine at, Guy's Hospital, London ; Physician to Evelina Hospital for Sick Chil- dren, and Examiner in Materia Medica and Pharmaceutical Chemistry, University of London. Cloth, 4.00 Roberts' Practice. New Revised Edition. A Handbook of the Theory and Practice of Medicine. By Frederick T. Roberts, m.d. ; m.r.c.p., Professor of Clinical Medicine and Therapeutics in University College Hospital, London. Seventh Edition. Octavo. Cloth, 5.50; Sheep, 6.50 Hughes. Compend of the Practice of Medicine. 4th Edi- tion. Two parts, each, Cloth, 1.00; Interleaved for Notes, 1.25 Part i.—Continued, Eruptive and Periodical Fevers, Diseases of the Stomach, Intestines, Peritoneum, Biliary Passages, Liver, Kidneys, etc., and General Diseases, etc. Part ii.—Diseases of the Respiratory System, Circulatory System and Nervous System; Diseases of the Blood, etc. Physicians' Edition. Fourth Edition. Including a Section on Skin Diseases. With Index. 1 vol. Full Morocco, Gilt, 2.50 From John A. fiobinson, M.D., Assistant to Chair of Clinical Medicine, now Lecturer on Materia Medica, Rush Medical Col- lege, Chicago. " Meets with my hearty approbation as a substitute for the ordinary note books almost universally used by medical students. It is concise, accurate, well arranged and lucid, . . . just the thing for students to use while studying physical diagnosis and the more practical departments of medicine." PRESCRIPTION BOOKS. Wythe's Dose and Symptom Book. Containing the Doses and Uses of all the principal Articles of the Materia Medica, etc. Seventeenth Edition. Completely Revised and Rewritten. Just Ready. 32mo. Cloth, 1.00; Pocket-book style, 1.25 Pereira's Physician's Prescription Book. Containing Lists of Terms, Phrases, Contractions and Abbreviations used in Prescriptions Explanatory Notes, Grammatical Construction of Prescriptions, etc., etc. By Professor Jonathan Pereira, m.d. Sixteenth Edition. 32mo. Cloth, 1.00; Pocket-book style, 1.25 PHARMACY. Stewart's Compend of Pharmacy. Based upon Remington's Text-Book of Pharmacy. Third Edition, Revised. With new Tables, Index, Etc. Cloth, 1.00 ; Interleaved for Notes, 1.25 Robinson. Latin Grammar of Pharmacy and Medicine. By H. D. Robinson, ph.d., Professor of Latin Language and Literature, University of Kansas, Lawrence. With an. Intro- duction by L. E. Sayre, ph.g., Professor of Pharmacy In, and Dean of, the Dept. of Pharmacy, University of Kansas. i2mo. Cloth, 2.00 SKIN DISEASES. Anderson, (McCall) Skin Diseases. A complete Text-Book, with Colored Plates and numerous Wood Engravings. 8vo. ^^ Cloth, 4.50; Leather, 5.50 -89" See pages 2 to S for list of New Manuals. STUDENTS' TEXT-BOOKS AND MANUALS. 13 Skin Diseases :—Continued. Van Harlingen on Skin Diseases. A Handbook of the Dis- eases of the Skin, their Diagnosis and Treatment (arranged alpha- betically). By Arthur Van Harlingen, m.d., Clinical Lecturer on Dermatology, Jefferson Medical College; Prof, of Diseases of the Skin in the Philadelphia Polyclinic. 2d Edition. Enlarged. With colored and other plates and illustrations. i2mo. Cloth, 2.50 Bulkley. The Skin in Health and Disease. By L. Duncan Bulkley, Physician to the N. Y. Hospital. Illus. Cloth, .50 SURGERY AND BANDAGING. Jacobson. Operations in Surgery. A Systematic Handbook for Physicians, Students and Hospital Surgeons. By W. H. A. Jacobson, B A., Oxon. f.r.c.s. Eng.; Ass't Surgeon Guy's Hos-, pital ; Surgeon at Royal Hospital for Children and Women, etc. 199 Illustrations. 1006 pages. 8vo. Cloth. 5.00; Leather, 6.00 Heath's Minor Surgery, and Bandaging. Ninth Edition. 142 Illustrations. 60 Formulae and Diet Lists. Cloth, 2.00 Horwitz's Compend of Surgery, Minor Surgery and Bandaging, Amputations, Fractures, Dislocations, Surgical Diseases, and the Latest Antiseptic Rules, etc., with Differential Diagnosis and.Treatment. By Orville Hokwitz, b.s., m.d., Demonstrator of Surgery, Jefferson Medical College. 4th edition. Enlarged and Rearranged. 136 Illustrations and 84 Formulae. i2mo. Cloth, 1.00; Interleaved for the addition of Notes, 1.25 *** The new Section on Bandaging and Surgical Dressings, con- sists of 32 Pages and 41 Illustrations. Every Bandage of any importance is figured. This, with the Section on Ligation of Arteries, forms an ample Text-book for the Surgical Laboratory. Walsham. Manual of Practical Surgery. For Students and Physicians. By Wm. J. Walsham, m.d., f.r c.s., Asst. Surg. to, and Dem. of Practical Surg, in, St. Bartholomew's Hospital, Surgeon to Metropolitan Free Hospital, London. With 336 Engravings. See Page 2. Cloth, 3.00; Leather, 3.50 URINE, URINARY ORGANS, ETC. Holland. The Urine, and Common Poisons and The Milk. Chemical and Microscopical, for Laboratory Use. Illus- trated. Third Edition. i2mo. Interleaved. Cloth, 1.00 Ralfe. Kidney Diseases and Urinary Derangements. 42 Illus- trations. i2mo. 572 pages. Cloth, 2.75 Marshall and Smith. On the Urine. The Chemical Analysis of the Urine. By John Marshall, m.d., Chemical Laboratory, Univ. of Penna; and Prof. E. F. Smith, ph.d. Col. Plates. Cloth, 1.00 Thompson. Diseases of the Urinary Organs. Eighth London Edition. Illustrated. Cloth, 3.50 Tyson On the Urine. A Practical Guide to the Examination of Urine. With Colored Plates and Wood Engravings. 6th Ed. Enlarged, umo. Cloth, 1.50 Van Nuys, Urine Analysis. Illus. Cloth, 2.00 VENEREAL DISEASES. Hill and Cooper. Student's Manual of Venereal Diseases, with Formulae. Fourth Edition. i2mo. Cloth, 1.00 49- See pages 14 and 15 for list of f Quiz-Compends f NEW AND REVISED EDITIONS. PQUIZ-COMPENDS? The Best Compends for Students' Use in the Quiz Class, and when Pre- paring for Examinations. Compiled in accordance with the latest teachings of promi- nent lecturers and the most popular Text-books. They form a most complete, practical and exhaustive set of manuals, containing information nowhere else col- lected in such a condensed, practical shape. Thoroughly up to the times in every respect, containing many new prescriptions and formuhe, and over two hundred and fifty illustrations, many of which have been drawn and engraved specially for this series. The authors have had large experience as quiz-masters and attaches of colleges, with exceptional opportunities for noting the most recent advances and methods. Cloth, each $1.00. Interleaved for Notes, $1.25. No. 1. HUMAN ANATOMY, " Based upon Gray." Fifth Enlarged Edition, including Visceral Anatomy, formerly published separately. 16 Lithograph Plates, New Tables and 117 other Illustrations. By Samuel O. L. Potter, m.a., m.d., late A. A. Surgeon U. S. Army. Professor of Practice, Cooper Medical College, San Francisco. Nos.2 and 3. PRACTICE OF MEDICINE. Fourth Edi- tion. By Daniel E. Hughes, m.d., Demonstrator of Clinical Medicine in Jefferson Medical College, Philadelphia. In two parts. Part I.—Continued, Eruptive and Periodical Fevers, Diseases of the Stomach, Intestines, Peritoneum, Biliary Passages, Liver, Kidneys, etc. (including Tests for Urine), General Diseases, etc. Part II.—Diseases of the Respiratory System (including Phy- sical Diagnosis), Circulatory System and Nervous System; Dis- eases of the Blood, etc. *** These little books can be regarded as a full set of notes upon the Practice of Medicine, containing the Synonyms, Definitions, Causes, Symptoms, Prognosis, Diagnosis, Treatment, etc., of each disease, and including a number of prescriptions hitherto unpub- lished. No. 4. PHYSIOLOGY, including Embryology. Fifth Edition. By Albert P. Brubaker, m.d., Prof, of Physiology, Penn'a College of Dental Surgery ; Demonstrator of Physiology in Jefferson Medical College, Philadelphia. Revised, Enlarged and Illustrated. No. 5. OBSTETRICS. Illustrated. Fourth Edition. By Henky G. Landis, m.d., Prof, of Obstetrics and Diseases of Women, in Starling Medical College, Columbus, O. Revised Edition. New Illustrations. BLAKISTON'S ?QUIZ-COMPENDS ? No. 6. MATERIA MEDICA, THERAPEUTICS AND PRESCRIPTION WRITING. Fifth Revised Edition. With especial Reference to the Physiological Action of Drugs, and a complete article on Prescription Writing. Based on the Last Revision of the U S. Pharmacopoeia, and including many unofficinal remedies. By Samuel O. L. Potter, m.a.-, m.d., late A. A. Surg U. S. Army; Prof, of Practice, Cooper Medical College, San Francisco. Improved and Enlarged, with Index. No. 7. GYNAECOLOGY. A Compend of Diseases of Women. By Henry Morris, m.d., Demonstrator of Ob tetrics, Jefferson Medical College, Philadelphia. 45 Illustrations. No. 8. DISEASES OF THE EYE AND REFRACTION, including Treatment and Surgery By L. Wbbster Fox, m.d., Chief Clinical Assistant Ophthalmological Dept., Jefferson Med- ical College, etc., and Geo. M. Gould, m.d. 71 Illustrations, 39 Formulae. Second Enlarged and . mproved Edition. Index. No. 9. SURGERY, Minor Surgery and Bandaging. Illus- trated. Fourth Edition. Including Fractures, Wounds, Dislocations, Sprains, Amputations and other operations ; Inflam- mation, Suppuration, Ulcers, Syphilis, Tumors, Shock, etc. Diseases of the Spine, Ear, Bladder, Testicles, Anus, and other Surgical Diseases. By Orville Horwitz, a.m., m.d., Demonstrator of Surgery, Jefferson Medical College. Revised and Enlarged. 84 Formulae and 136 Illustrations. No. 10. CHEMISTRY. Inorganic and Organic. For Medical and Dental Students. Including Urinary Analysis and Medical Chemistry. By Henry Leffmann, m.d., Prof, of Chemistry in Penn'a College of Dental Surgery, Phila. Third Edition, Revised and Rewritten, with Index. No. 11. PHARMACY. Based upon " Remington's Text-book of Pharmacy." By F. E. Stewart, m.d., ph.g., Quiz-Master at Philadelphia College of Pharmacy. Third Edition, Revised. No. 12. VETERINARY ANATOMY AND PHYSIOL- OGY. 29 Illustrations By Wm. R Ballou, m.d., Prof, of Equine Anatomy at N Y. College of Veterinary Surgeons. No. 13. DENTAL PATHOLOGY AND DENTAL MEDI- CINE. Containing all the most noteworthy points of interest to the Dental student. By Geo. W. Warren, dd.s., Clinical Chief, Penn'a College of Dental Surgery, Philadelphia. Illus. No. 14. DISEASES OF CHILDREN. By Dr. Marcus P. Hatfield, Prof, of Diseases of Children, Chicago Medical College. Colored Plate. Bound in Cloth, $1. Interleaved, for the Addition of Notes, $1.25. 3@°" These books are constantly revised to keep up with the latest teachings and discoveries, so that they contain all the new methods and principles. No series of books are so complete in detail, concise in language, or so well printed and bound. Each one forms a complete set of notes upon the subject under consideration. Illustrated Descriptive Circular Free. JUST PUBLISHED. GOULD'S NEW Medical Dictionary It contains Tables of the Arteries, Bacilli, Gan- glia, Leucomalnes, Micrococci, Muscles, Nerves, Plexuses, Ptomaines, etc., etc., that will be found of great use to the student. Small octavo, 520 pages, Half-Dark Leather, . #3.25 With Thumb Index, Half Morocco, marbled edges, 4.25 From J. M. DaCOSTA, M. D., Professor of Practice and Clinical Medicine, Jefferson Medical College, Philadelphia. "Ifind it an excellent work, doing credit to the learning and discrimination of the author." *** Sample Pages free. A UNIQUE BOOK. POTTER'S MATERIA MEDICA, PHARMACY AND THERA- PEUTICS. Second Edition. Revised and Enlarged. A Hand- book; including the Physiological Action of Drugs, Special Therapeutics of Diseases, Official and Extemporaneous Pharmacy, etc. By S. 0. L. Potter, m.a., m.d., Professor of the Practice of Medicine in Cooper Medical College, San Francisco; Late A. A. Surgeon, U. S. Army, etc. A new Edition in larger type. Octavo. Cloth, #4.00; Leather, #5.00. Dr. Potter has become well known as an able compiler, by his Compends of Anatomy, and of Materia Medica, both of which have reached four editions. In this book, more elaborate in its design, he has shown his literary abilities to much better advantage, and all who examine or use it will agree that he has produced a work containing more correct information in a practical, concise form than any other publication of the kind. The plan of the work is new, and its contents have been combined and arranged in such a way that it offers a compact statement of the subject in hand. Part I.—Materia Medica and Therapeutics, the drugs being arranged in alphabetical order, with the synonym of each first; then the description of the plant, its preparations, physiological action, and lastly its Therapeutics. This part is preceded by a section on the classification of medicines as follows: Agents acting on the Nervous System, Organs of Sense, Respiration, Circu- lation, Digestive System, on Metabolism (including Restoratives, Alteratives, Astringents, Antipyretics, Antiphlogistics and Antiperiodics, etc.). Agents act- ing upon Excretion, the Generative System, the Cutaneous Surfaces, Microbes and Ferments, and upon each other. Part II.—Pharmacy and Prescription Writing. Written for the use of physicians who put up their own prescriptions. It includes—Weights and Measures, English and the Metric Systems. Specific Gravity and Volume. Prescriptions.—Their principles and combinations; proper methods of wr.ting them; abbreviations used, etc. Stock solutions and preparations, such as a doctor should have to compound his own prescriptions. Incompatibility, Pharmaceutical and Therapeutical. Liquid, Solid and Gaseous Extempo- raneous Prescriptions. Part III.—Special Therapeutics, an alphabetical List of Diseases—a real Index of Diseases—giving the drugs that have been found serviceable in each disease, and the authority recommending the use of each; a very im- portant feature, as it gives an authoritative character to the book that is unusual in works on Therapeutics, and displays an immense amount of research on the part of the author. 600 prescriptions are given in this part, many being over the names of eminent men. The Appendix contains lists of Latin words, phrases and abbreviations, with their English equivalents, used in medicine, Genitive Case Endings, etc. 36 Formulae for Hypodermic Injections; a comparison of 10 Formulae of Chloro- dyne; Formulae of prominent patent medicines; Poisons and their Antidotes; Differential Diagnosis; Notes on Temperature in Disease; Obstetrical Memo- randa; Clinical Examination of Urine; Medical Ethics; Table of Specific Gravities and Volumes; Table showing the number of drops in a fluidrachm of various liquids and the weight of one fluidrachm in grains, and a table for converting apothecaries' weights and measures into grams. A MINE OF WEALTH FOR THE STUDENT. Standard Text-Books. LANDOIS' HUMAN PHYSIOLOGY. A Text-Book of Human Physi- ology, including Histology and Microscopical Anatomy, with special reference to the requirements of Practical Medicine. By Dr. L. Landois, Professor of Physiology and Director of the Physiological Insti- tute, University of Greifswald. Translated from the Fifth German Edition, with additions by Wm. Stirling, m.d., Sc.d., Brackenburg, Professor of Physiology and Histology in Owen's College and Victoria University, Man- chester ; Examiner in the Honors' School of Science, University of Ox- ford, England. Third Edition, revised and enlarged. 692 Illustrations. One Volume. Royal Octavo. Cloth, $6.50; Leather, #7.50. "With this Text-book at command, no Student could fail in his examination."— The Lancet. "One of the most practical works on Physiology ever written, forming a 'bridge' be- tween Physiology and Practical Medicine. ... Its chief merits are its completeness and conciseness. . . . Excellently clear, attractive and succinct. "—British Medical Journal. " Unquestionably the most admirable exposition of the relations of Human Physiology to Practical Medicine ever laid before English readers."—Students' Journal. " Landois' Physiology is, without question, the best text-book on the subject that has ever been written."—New York Medical Record. CAZEAUX AND TARNIER'S MIDWIFERY. Eighth Revised and Enlarged Edition. With Appendix, by Munde. The Theory and Practice of Obstetrics; including the Diseases of Pregnancy and Parturition, Obstetrical Operations, etc. By P. Cazeaux, Member of the Imperial Academy of Medicine. Remodeled and rearranged, with revisions and additions, by S. Tarnier, m.d., Prof, of Obstetrics and Diseases of Women and Children in the Faculty of Medicine of Paris. Eighth American, from the Eighth French and First Italian Editions. Edited and Enlarged by Robert J. Hess, m.d., Physician to the Northern Dispensary, Phila., etc., with an Appendix by Paul F. Munde, m.d., Professor of Gynaecology at the New York Polyclinic, Vice-President American Gynaecological Society, etc. With Chromo-Lithographs, Litho- graphs, and other Full-page Plates, seven of which are beautifully colored, and numerous Wood Engravings. One Volume, octavo. Cloth, #5.00; Full Leather, 56.00. MEYER ON DISEASES OF THE EYE. A Manual of Ophthal. mology. By Dr. Edouard Meyer, Prof, a l'Ecole Pratique de la Faculty Medecine de Paris; Chevalier of the Legion of Honor, etc. Translated from the Third French Edition, with the assistance of the author, by Dr. Freeland Fergus, Assistant Surgeon, Glasgow Eye Infirmary. With 267 Illustrations and three Colored Plates. Prepared under the direction of Dr. R. Liebreich. 8vo. Cloth, $4.50; Leather, #5.50. The first chapter is an explanation of the best means for examining the eyes, externally and internally, with a view to diagnosis, the various ophthalmo- scopes, general considerations on the treatment of ophthalmia, etc. Each dis- ease is then taken up in its proper order; the anatomy of the part being pre- sented first, followed by the diagnosis, causes, progress, prognosis, etiology and Jreatment. The arrangement of the work will thus be seen to be systematic, commending itself to all physicians and students for the logical and concise way in which the facts are given. This English edition makes the eighth language into which Meyer's book has been translated. P. BLAKISTON, SON & CO., Publishers and Booksellers, 1012 WALNUT STREET, PHILADELPHIA The New York Academy of Medicine This book must not be retained for longer than one week after the last date on the slip unless permission for its renewal be obtained from the library. NATIONAL LIBRARY OF MEDICINI Bethesda, Maryland Gift of The New York Academy of Medicine Standard Text-Books.« HORLn?vEN^ rANAT°MY' A Manual of the Dissections of the Human «nrfw i X L,UTHE* Holden, f.r.cs. Fifth Edition. Carefully Revised and Enlarged, specially concerning the Anatomy of the Nervous System Organs of Special Sense, etc. By John Langton, f.r.cs., Surgeon to, and Lecturer on Anatomy at, St. Bartholomew's Hospital. 208 Illustrations 8vo. Cloth, #5.00; Leather, #6.00. Oil-cloth Covers, for the Dissecting Room, $4.50. KlJ^L3°Pular!ty °f 'his, w1rk has steadily increased during the past few years It is proba- nd and I^nof re^n iL^H- f^'V di?\CtorJ. Th' Oil-cloth binding allows of 3- rafiX r,r?nt?H £a I A dlr'and odor °j the dissecting table. This edition has been oareiully printed and bound, and lays open flat at any page. " No student of anatomy can take up this book without being pleased and instructed Its dSfon "aTa?' -St!;lking V* ^SU^«tive, giving more a? I glance «h« ££s of tert work Pbut it itllt 'S H"°W" t(?> th°f Wh0 are a readV acquainted with this ^admirable S«enoiiti»i^ I ] A? l° ? value'as a work f°r ireful study and reference, that llustrE, inH;?} ,t0 SUC-h ? are,.COmmencinS their studies, the text matches the icalRe d d'nsctness 0f practlcal application and clearness of detail."—New York Med- ANDERSON ON SKIN DISEASES. A complete Treatise on Skin Diseases. By McCall Anderson, m.d., Professor of Clinical Medicine, University of Glasgow. With numerous wood engravings and several col- ored and steel plates. Octavo. Cloth, #4.50. Leather, #5.50. Just Ready. This aims to be a complete text-book. It will be found to contain all the latest methods ot treatment. The subject is dealt with in a systematic, practical manner, and is based on an extensive experience of nearly twenty-five year*. GOWERS* MANUAL OF DISEASES OF THE NERVOUS SYSTEM. A Complete Text-book. By William R. 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" In short, the book is brought up to the standard of to-day, and in most respects may be considered a reliable, practical text-book, written by an earnest worker and practical man." "—American Journal of Medical Sciences. ROBERTS. PRACTICE OF MEDICINE. The Theory and Prac- tice of Medicine. By Frederick Roberts, m.d., Professor of Thera- peutics at University College, London. Seventh American Edition, thoroughly revised and enlarged, with new Illustrations. 8vo. Cloth, $5.50; Leather, $6.50. " If there is a book in the whole of medical literature in which so much is said in so few words, it has never come within our reach."—Chicago Medical Journal. " The best text-book for students. We know of no work in the English language, or of any other, which competes with this one."—Edinburgh Medical Journal. V. BLAKISTON, SON & CO., Publisher* and Booksellers, 1012 WALNUT STREET, PHILADELPHIA.