THE LIBRARY OF THE UNIVERSITY OF CALIFORNIA LOS ANGELES The book will be found useful, not only as a Text Book under a teacher, but also for self-study. The American LABORATORY MANUAL OF i < MEDICAL AND PHARMACEUTICAL. By OSCAR O l-IHt l.i:;. Pharni. !>., Professor of Pharmacy and Director of the Pharmaceutical Laboratories in the Illi- nois College of Pharmacy Northwestern University. And JOHN II. M\4.. Sc. !>.. Professor of Chemistry and Director of the Chemical Laboratories of the Chicago Medical College and the Illinois College of Pharmacy Northwestern University. WITH ORIGINAL ILLUSTRATIONS. Our object in preparing this manual was to provide in convenient form a sufficient number of suitable lessons in laboratory work, and at the same time to embody in the book the facts of inorganic chemistry most important to pharmacy and medicine. It contains experiments intended to familiarize the student with the properties of the -principal elements, lessons in synthetical chemistry, a systematic course in qualita- tive analysis, examples in quantitative determinations, including the official methods of assay for a few important drugs, and a short chapter on the chemical and micro- scopical examination of urine. Among the lessons in Part II will be found the working formula? of the pharma- copoaias for many of the preparations. Students pursuing synthetical work without an instructor can successfully and with benefit make most of the pharmaceutical preparations included in the Second Part, with the aid of the explanatory notes it contains. For purposes of practice the quantities of materials operated upon may, of course, be small and the outfit of appa- ratus limited to the list given in the appendix. OPINIONS OF THE PRESS. " The book cannot fail to be a serviceable one, both to students in colleges and to those unable to avail themselves of the advantages of a school. The appendix con- tains, in addition to useful tables for reference, a list of reagents and of the apparatus required for carrying out the experiments described." The Pharmaceutical Era. " Although there are chemistries without number, this is the first laboratory manual adapted to our Pharmacopoeia that has been offered to American Pharmacists. * * * One important and commendable feature noticeable throughout the entire book is the close adherence to the most approved chemical nomenclature, which with the excellent typographical work makes it far superior to the English books of the same class. * * ' The descriptions and cuts of chemical apparatus will be found useful to those studying without a teacher. The tables make it a very convenient book of reference." The Polyclinic. " In the arrangement of this work, the authors have steadily kept practice to the front, theory taking a second place. * " * * The Pharmaceutical student will find it a convenient laboratory manual in which all the more important facts of inorganic chemistry are well set forth." The Druggist Circular. "It contains all that any medical student can hope to learn, with directions how to do it, and very much more than many teachers of medical chemistry know. IT IS THE LABORATORY MANUAL FOR THE STUDENT." Journal of the American Medical Association. OflK VOLUME, SVO. CLOTH, - *3.5O XKT. Mailed Postpaid on receipt of the Price. Specimen Page, Table of Contents, etc., sent free upon application. Howknrller and Irnjwrtt'f, 96 "Washington St., CHICAGO. THE DENTAL COLLEGE SERIES OF TEXT-BOOKS. DENTAL CHEMISTRY AND METALLURGY. BEING THE SECOND EDITION OF THE DENTIST S MANUAL OF SPECIAL CHEMISTRY, REVISED, REWRITTEN, AND INCLUDING : 1. ESSENTIALS OF CHEMISTRY FOR DENTAL STUDENTS. 2. GENERAL CHEMISTRY FOR DENTAL PRACTITIONERS. 3. LABORATORY COURSE IN ELEMENTARY CHEMISTRY FOR DENTAL STUDENTS. 4. LABORATORY COURSE IN DENTAL CHEMISTRY AND METAL- LURGY. BY CLIFFORD MITCHELL, M. D. CHICAGO : W. ee "^ 2O9 . 23rd -^ N. V. CITY -V '/ \^>/ // Lf, * S^ ' 6 f,p V:-^^- Copyright. CLIFFORD MITCHELL, M. D. 1889. '# <\ & *3 . TO THE MEMORY OF 1VTARIA IVIITCH THIS BOOK IS DEDICATED BY HER NEPHEW THE AUTHOR. PREFACE TO THE SECOND EDITION The Dentist's Manual of Special Chemistry has been revised and almost rewritten. To the chapter on Physics has been added considerable matter relating to Electricity as well as to Percentage Solutions, Specific Volume, and the like. In place of the chapter on Chemical Theory, I have prepared one on Chemical Philosophy, much fuller in details and with more attention to explanation. This I have done in accordance with a suggestion made by a writer in the Cosmos, who reviewed my first edition. In the course of the chapter on Chemical Philosophy, I have inserted a table, kindly furnished by Professor Seaman, on the Constants of the Elements. By permission of Pro- 'fessor John Howard Appleton, I have used the revised atomic weights of the elements, as found in his excellent " Laboratory Year-book." At the suggestion of Professor Salisbury, I have paid especial attention to the considera- tion of Double Decomposition and Chemical Equations. Classifications of the elements, according to Mendeleef and Lothar Meyer respectively, have been given. But the order in which the elements are presented to the student in Chapter III is strictly according to Valence, that is, Monads first, then Dyads, Triads, etc. Monads vi PREFACE. positive to hydrogen are studied before those negative to it. In this way, both the combining power of the elements and the quality of that power are impressed on the memory of the reader. Objections can be made to almost any classification of the elements, but, after due considera- tion and consultation, it has been decided to present the subject entirely from the standpoint of combining power. The dentist will find the oxychloride cement, for exam- ple, included in the subject of Zinc, among the Dyads ; amalgams in the subject of Mercury, among the Dyads and so on. The chapter on Organic Chemistry has been brought up to date by the consideration of many new alkaloids and antiseptics. By far the most important change in the book is the insertion of much new matter in the chapters on Laboratory Work. I have arranged in the first place a short course of simple experiments, illustrating princi- ples of General Chemistry, so easy that any one of intelli- gence, however unfamiliar with chemistry, can perform them. Following these is inserted a course of sixty experiments, progressive in character, illustrating the practical application of chemical principles to dentistry. This latter course of experiments is kindly contributed by Professor J. H. Salisbury, and should prove of decided value in interesting the dental student in chemistry. The only method by which any real interest in chemistry can be aroused in the majority of students is by means of practical work in the chemical laboratory. It is hoped that the experiments outlined in this volume will be of use to those beginning chemistry in the Dental Colleges, and that many will be led to further study and research. There is no reason why in due time there should not be men as enthusiastic in the study of chemistry as applied to dentistry, as there are now in the study of chemistry as applied to medicine. Courses on Special Chemistry in PREFACE. vii American Dental Colleges are already given, and it is safe to predict that ten years from now the course in chemistry for the dental student will be distinct from that of the medical student, except, possibly, in a few minor particu- lars. \I know of no professional man to whom chemistry will eventually prove more valuable than to the dentist. Many of the most perplexing problems with which the dentist has now to deal will in due time be solved by the dental chemist.^The labor of revising the first edition o this book has been cheerfully undertaken in consequence of cordial appreciation on part of the dental profession of the author's humble efforts. I must acknowledge help from the following sources : Professor J. H. Appleton, Brown University, permis- sion to quote from his Laboratory Year-book ; Professor Thos. H. Chandler, Harvard University, many suggestions concerning subjects of interest to the dentist, as, for example, Amalgam Alloys ; Mr. J. G. M. Glessner, Chi- cago, thorough typographical revision of the first edition ; Professor N. S. Ho ft', Michigan University, suggestion from Professor Ford regarding a Glossary ; Professor H. G. Meriam, Harvard University, matter of interest concerning dental rubbers; Dr. W. H. Rollins, Boston, notes on oxyphosphate cement and other materials ; Pro- fessor J. H. Salisbury, Lake Forest University, many sug- gestions as to Chemical Philosophy, and contribution of a course in Laboratory Work ; Professor W. H. Seaman, Howard University, suggestions regarding Chemical Physics, and contribution of a Table of Constants of the Elements. 70 STATE STREET, SEPTEMBER ist, 1889. CONTENTS. CHAPTER I. Physics: Mass, molecule, atom, molecular motion, ato- mic motion, properties of matter chemical and physical, im- penetrability, magnitude, divisibility, porosity, compressibility, expansibility, elasticity, mobility, cohesion, adhesion, hardness, brittleness, tenacity, malleability, ductility. States of matter solid, liquid, gaseous, radiant ; machines, levers, planes, wedge, screw, friction, capillarity, specific gravity, density, heat, distil- lation, solution, solubility, crystallization, crystals, light, elec- tricity, electrolysis, electricity in the mouth, weights and meas- ures, metric system, percentage solutions, conversion of vol- ume to weight, thermometry Pages 1 to 31. CHAPTER II. Chemical Philosophy: Molecule, atom, element, compound, symbols, table of constants of the elements, writing symbols, atomic weight, positive and negative elements, quan- tivalence, artiads and perissads, compound molecules, law of definite and multiple proportions, binary compounds, radicals, ternary compounds, acids, bases, salts, how to read formulas, ammonium compounds, nomenclature old and new, chemical change, reactions, laws of double decomposition, insoluble sub- stances, volatile compounds, chemical equations, chemical arithmetic, circumstances influencing chemical attraction : Mendeleef's tables of the elements, Lothar Meyer's classifica- tion, general properties of the metallic elements, general prop- erties of alloys of metallic elements Pages 32 to 91. CHAPTER III. Inorganic Chemistry. Monads: Potassium, sodium, [ammonium], lithium, silver, hydrogen, iodine, brom- ine, chlorine, fluorine, and their compounds. Dyads: Barium, calcium, magnesium, zinc, cadmium, lead, uranium, copper, mercury, tellurium, sulphur, oxygen, and their compounds. Amalgams: Rollins's copper amalgam, Chand- ler's, Weagant's processes, Bogue's process, Ames's process; dental amalgam alloys. Compounds of mercury; corrosive sublimate, calomel, vermilion; compounds of sulphur; action of sulphuretted hydrogen on metals. X CONTENTS. Triads: Bismuth, gold, antimony, boron, arsenicum, phos- phorus, nitrogen, and their compounds. Gold '.- occurrence, preparation, properties. Refined gold, chemically pure gold, agents used for precipitating gold, crystal gold, beating gold, cohesive gold, corrugated gold, effect on gold of alloying, ap- pearance of gold alloys, gold base plate, compounds of gold, purple of Cassius. Phosphoric acid, common and glacial. Nitrogen monoxide or laughing gas, nitric acid. Tetrads: Aluminium, cerium, //w.palladium, platinum, irid- ium, silicon, titanium, carbon, and their compounds. Alums, artificial teeth, enamels, platinum, colors for enamels, silex, rutile. Hexads: Manganese, iron, nickel, cobalt, chromium, and their compounds. Cobalt blues. Chromic oxide, anhy- dride or "acid" Pages 92 to 213. CHAPTER IV. Organic Chemistry Theory: radicals, chains, homologous series, types, substitution, derivatives, isomerism, decomposition, combustion and decay, fermentation, putre- faction. Hydrocarbons: paraffines, mineral oil, vaselene, oil of turpentine, terpenes, essential oils; oil of cloves, eugenol; India-rubber, dental rubber, gutta-percha, camphor, resins, myrrh, gums, naphthalene, naphthols. Ethyl series of radicals, alcohols, alcohol. Glycerine, glycerites, boroglyceride, glycer- oborates. Creasote. Carbolic acid. Phenol compounds, resor- cin, eucalyptol. Carbohydrates: sugars, honey, gums, col- lodion, celluloid. Ethers: chloroform, iodoform, iodol; alde- hydes: paraldehyde, chloral hydrate. Ketones. Organic acids: acetic, trichloracetic, benzoic, eugenic, hydrocyanic, oleic, oxalic, lactic, salicylic, [salol, betol] sozolic, tartaric, [tartar emetic]. Alkaloids: aconitine, atropine, chinoline, can- nabine, cocaine, morphine, quinine, strychnine, veratrine, "anti- pyrine", "antifebrine", alstonine, apomorphine, caffeine, cytis- ine, ditaine, erythrophleine, ethyl-oxy-caffeine,hyoscyamine,is- atropyl cocaine, jerubebine, lamine,oxy-propylene-di-iso-amyl- amine, ulexine. Proteids: albumins, globulin, etc. Fermen- tation. Ferments. Putrefactive fermentation in the mouth. Fungi. Bacteria. Microbe of dental caries. Pus and sup- puration. Disinfection: antiseptics, germicides, disinfectants. Miller s mouth washes. Deodorizers. Antiseptics: alantol, betol, bismuth oxyiodide.creolin, cresylic acid, iodine trichlor- ide, mercuric albuminate, mercuric oxy-cyanide, oxy-naphthoic acid, tribrom-phenol, sodium silico-fluoride Pages 214 to 308. CONTENTS. XI CHAPTER V. The Teeth and the Saliva: Tooth structure, chem- ical constitution of the teeth. Enamel, dentine, cement. Table of analyses. Action of various substances on the teeth. Chem- istry of caries; chemical theory, vital theory, germ theory. The saliva: physical characters, chemical composition, func- tions, changes; parotid saliva, submaxillary, sublingual; buc- cal_ mucus. Tartar. Salivary calculi Pages 309 to 329. CHAPTER VI. Practical Work in Dental Chemistry progressively arranged: I. Short course of a score of experiments illustrat- ing, principles of general chemistry. II. Professor J. H. Salisbury's course of sixty experiments illustrating the practical application of chemistry to dent- istry Pages 330 to 342. CHAPTER VII. Practical Work in Dental Chemistry Continued. III. Short course in blowpipe analysis. IV. Reactions of the more important metals in the wet way: silver, lead, mercury, copper, gold, platinum, zinc, tin, alum- inium. V. Short scheme for qualitative analysis of ordinary metals Pages 343 to 361. CHAPTER VIII. Chemical Work in the Dental Laboratory: Refin- ing gold, testing amalgams, manipulating vulcanite, compound- ing rubber. Short method of qualitative and quantitative analysis of dental amalgam alloys. Analysis of cements. Testing rubbers.. Pages 362 to 377. CHAPTER IX. Complete Course in Salivary Analysis: Analysis of teeth, tartar, and of urine Pages 378 to 393. Glossary Pages 394 to 399. Index.. Pages 400 to 411. THE Dentist's Manual of Special Chemistry. Second. Edition. CHAPTER I. PHYSICS. 1. Matter. Anything; which possesses weight or occupies space. 2. Divisions of Matter. Mass, molecule, atom. (See also page 33). 3. Mass. Quantity of matter made up of molecules. 4. Molecule. Smallest subdivision of mat- ter which can exist by itself. 5. Atom. Smallest quantity of matter that can by combining" form the molecule. 6. Attraction of Mass, or molar attraction: same as attraction of gravitation or tendency of bodies to ap- proach one another. 7. Molecular Attraction. Cohesion or adhesion. 8. Atomic Attraction. Chemism or chemical affinity. 9. Molar Motion. The ordinary, visible, mechanical motion, as that of a machine or its parts. DENTAL CHEMISTRY. 10. Molecular Motion. Heat, light, magnetism, elec- tricity. 11. Atomic Motion. A constant revolution or swing- ing of the atom within a limited space. 12. Properties of Matter. Qualities char- acteristic of matter. Two kinds, chemical and physical. 13. Chemical Properties. Those resulting from the composition of the molecule with reference to its atoms and shown only by change of identity of the molecule: as com- bustibility, explosibility, etc. 14. Physical Properties of Matter. The different ways in which matter presents itself to our senses. Two kinds, general and specific, or universal and characteristic. General properties are those common to all matter, as impenetrability, extension, porosity, etc. Specific properties are those observed in cer- tain bodies only, or in certain states of those bodies, as solidity, color, tenacity, etc. Physi- cal properties may be shown without change in the identity of the molecule. 15. Physical Properties: Impenetrability. Prop- erty of matter in virtue of which two bodies cannot occupy the same space at the same time. Example: nail driven into wood, particles of wood make way for the nail. 16. Extension or Magnitude. Property in virtue of which every body occupies a limited portion of space. 17. Divisibility. Property of matter by virtue of which a body may be separated into distinct parts. Di- PHYSICS. 3 visibility of matter practically limited before molecule is reached; theoretically should be limited by the atom. 1 8. Porosity. Quality in virtue of which spaces or pores exist between the molecules of a body. Example: lead, if hammered, is made smaller because the size of the pores is reduced, the molecules being forced nearer together. 19. Compressibility. Property in virtue of which a body may be reduced in size; it is a consequence and proof of porosity. 20. Expansibility. Property in virtue of which a body may be increased in size. Opposite of compressi- bility. Example: iron when heated becomes larger or expands because its molecules are pushed further apart. 21. Elasticity. Property in virtue of which bodies resume their original form or volume (size) when that form or volume has been changed by external force. Example: a piece of ordinary rubber after being stretched out resumes its original size when the force stretching it ceases to act. 22. Mobility. Property in virtue of which the posi- tion of a body may be changed. Inertia is the incapa- bility of matter to change its own state of motion or rest. Example: a book on a table cannot move itself and is said to have inertia', it can move, however, when sufficient force is applied to it and is said to have mobility. 23. Cohesion. Force which unites mole- cules of the same kind as two molecules of water or two molecules of iron. Cohesion holds substances together and gives them form. 24. Adhesion. Force which unites mole- cules of different kinds. Example: dip a glass rod into water and, on withdrawing it, a drop DENTAL CHEMISTRY. will be found at its lower extremity, which re- mains suspended or adheres to it. 25. Hardness. Property in virtue of which some bodies resist attempts to force passage between their particles. Example: a tooth possesses hardness. 26. Brittleness. Property in virtue of which some bodies may easily be broken. Ex- ample: glass is not only hard, but is also easily broken or brittle. 27. Tenacity. Property in virtue of which some bodies resist attempts to pull their par- ticles asunder. Example: an iron wire is diffi- cult to pull apart and is said to be tenacious. Tenacity is proportional to sectional area: a rod of one square inch sectional area* will carry twice the load that a rod of the same material with sectional area of half a square inch will carry. 28. Malleability. Property in virtue of which some bodies may be hammered or roll- ed into sheets. Example: gold can be beaten into sheets so thin that nearly 300,000 are necessary to measure an inch in height when they are placed one on another. 29. Ductility. Property in virtue of which some bodies may be drawn into wire. Ex- ample: iron when heated may be drawn into a wire, hence is said to be ductile. *The sectional area of a substance as, for example, a rod, is that of the surface of its cross section, PHYSICS. 30.. States of Matter. Solid, liquid, gas- ous, and radiant. In the first, the attraction of the molecules is greater than their repulsion. In the second, their attraction and repulsion are equal. In the third, repulsion is greater than attraction. In the fourth, so few mole- cules are in the given space that they rarely strike each other in their paths of motion. Fluid is a term applied to any thing which will adapt itself to the sides of the ves- sel containing it, hence includes both liquids and gases. Yapors are gases produced by heat from substances usually solid or liquid at or- dinary temperatures. Examples: solids: wood, metals \fluids: air, water; liqttids: water, oil, alcohol; gases: air, oxygen, hydrogen; vapor: steam. 31. Force. Cause tending to produce, change, or de- stroy motion. Example: gravity, friction, electrical or magnetic attraction, etc. 32. Work. Overcoming of resistance. 33. Energy. Power of doing work. 34. Foot-pound. Amount of work required to raise one pound one foot high.* 35. Horse-power. Ability to perform 33,000 foot- pounds in a minute. 36. Machine. Contrivance for utilizing energy by *The work required to raise one kilogram through one meter, against the force of gravity, is called a kilogram-meter. 6 DENTAL CHEMISTRY. which power can be applied more advantageously to resist- ance and, in general, intensity of energy be transformed. 37. Laws of Machines. I. Gain in intensity of power =loss in time, velocity, or distance and vice versa. 2. Power X distance=weight X distance. 3. Power X velocity=weight X velocity. 38. Lever. Any inflexible bar, straight or curved, resting on a fixed point or edge called the fulcrum. Every lever has two arms, the power-arm and the weight-arm. The power-arm is the perpendicular distance from the fulcrum to the line in which the power acts; the weight- arm is the perpendicular distance from the fulcrum to the line in which the weight acts. When the lever is not a straight bar, or when power and weight do not act parallel to each other, the lever is called a bent lever. 39. Rinds of Levers. ( i )Fulcrum between power and resistance (weight) as in crowbar, (2)weight between power and fulcrum as in wheelbarrow, (3) power between weight and fulcrum as in human forearm. 40. Laws of the Lever. Power X power-arm=weight X weight-arm. A given power will support a weight as many times as great as itself, as the power-arm is times as long as the weight-arm. The continued product of the power and lengths of the alternate arms beginning with the power-arm=the con- tinued product of the weight and lengths of the alter- nate arms beginning with the weight-arm. 41. Law of Wheel and Axle. The power multiplied by the radius, diameter, or circumference of the wheel= the weight X the corresponding dimension of the axle. 42. Pulley. A wheel, turning on an axis, provided with a cord, which passes over the grooved circumference of the wheel. The axis is supported by a frame called the block. PHYSICS. 7 43. Inclined Plane. Hard, smooth, inflexible surface used in most cases to aid in the performance of work against the force of gravity. It is inclined so as to make an oblique angle with the direction of the force to be overcome, and in most cases is inclined to the horizon at an acute angle. 44. Wedge. Movable inclined plane in which power usually acts in a direction parallel to base. It is used for moving great weights short distances. More commonly a wedge is two inclined planes united at their base. With given thickness, the longer the wedge the greater the gain in intensity of power. 45. Screw. Cylinder with spiral groove or ridge, called the thread, winding about its circumference. By aid of the screw a given power will support a weight as many times greater than itself as the circumference described by the power is times as great as the distance between two adjoining turns of the thread. 46. Friction. Resistance encountered by a moving body from the surface on which it moves. Is greatest at beginning of motion, increases with roughness of sur- faces, greater between soft bodies than hard .ones, is nearly proportional to pressure, is not affected by extent of surface within ordinary limits, is greater between sur- faces of the same material than between those of differ- ent kinds; rolling friction less than sliding friction; friction diminished by polishing or lubricating the surfaces. 47. Capillarity. When a glass rod is placed verti- cally in water the latter rises above its level at the sides of the glass. The finer the rod the greater the capillary ascent. If the rod be dipped into a liquid which does not wet it, as mercury, the liquid will be depressed instead of raised. 48. Displacement. A body which sinks in water dis- DENTAL CHEMISTRY. places exactly its own bulk of water and loses in weight an amount just equal to the weight of water displaced. 49. Specific Gravity. Relative weights of equal bulks of bodies referred to an assumed standard; for liquids and solids, the standard is distilled water at a temperature of 4 C. or 39.2 F. For gases, the standard is air or hy- drogen. If a substance weighs four times as much as the same bulk of water, it is said to have a sp. gr. of 4. 50. Calculation of Specific Gravity of Solids and Liquids. (a) For solids use the fol- lowing formula: W Sp. gr. W W 1 in which W= weight of body in air, W 1 its weight in water (suspended by a light thread from the scale pan). Example: weight of a body in air, i. e., ordinary weight, is 50 ounces; its weight in water is 42 ounces. \Y=5o, W 50 W 1 =42, W W^so 42 or 8;- ==6.25, W W 8 sp. gr. In other words the weight of the body divided by the weight of an equal volume (bulk) of water is the specific gravity of the body. (^)If the body is lighter than water, fasten a heavy body to it and weigh in water. Weigh the heavy body in water. Weigh the light PHYSICS. body in air. Then subtract the water weight of the combined mass from the water weight of the heavy body, and add to the difference the air weight of the light body. Then divide air weight of cork by the sum. Example: re- quired to find the specific gravity of a piece of cork. Attach to it a piece of iron: 1. Weight of combined mass in water - 51.5 grains. 2. Weight of iron in water - 66.9 grains. 3. Weight of cork in air 4.6 grains. 4. 66.951.5=15.4. 5. 15.4+4.6=20. 4.6 6. - - =0.23, sp. gr. of cork. 20 (c) To find the sp.gr. of solids which dis- solve in water, weigh them in some liquid in which they are insoluble, and find the specific gravity as before. Multiply result by specific gravity of liquid used and the product will be the true specific gravity. Example: to find specific gravity of sugar. Suppose it weighs 10 grains in air and 4.56 grains in oil of tur- pentine. 10 4.56=5.44 grains. 10 1-5. 43=1. 84 or sp. gr. referred to turpentine. Ascertain from tables the sp. gr. of turpentine(=o.86), multi- ply 1.84 by 0.86, and the product, 1.58, is the true sp. gr. of the sugar. (^ grammes ............. 28.349 1 ounce, troy or apothecary (480 gr.)31 grammes ............... 31.103 BULK. 1 Cubic centimetre ............... 0.06 cubic inch ............. 0.061 1 cubic inch ...................... 16 X Cubic centimetres ..... 16.386 1 litre (1000 Cubic centimetres) ---- 1 U. S. standard quart ..... 0.946 1 United States quart .............. 1 litre ..................... 1.057 1 fluidounce ....................... 29^ Cubic centimetres ____ 29.570 LENGTH. Uni, of measurement. 1 inch ........................ 2 l / 2 centimetres ................ 2.539 1 centimetre (1-100 metre) ..... 0.4 inch ....................... 0.393 1 yard ........................ 1 metre ....................... 0.914 1 metre (39.37 inches) .......... 1 yard ........................ 1.093 1 foot ......................... 30 centimetres ................ 30.479 1 kilometre (1000 metres) ....... % mile ....................... 0.621 1 mile ......................... \ l / 2 kilometres ................ 1.609 SURFACE. 1 hectare (10,000 square metres). . . 2 l / 2 acres .................. 2.471 1 acre ........................... I hectare .............. 0.404 Suppose we are directed to use 175 grammes of chlo- ride of sodium, how much is it in ounces? We see by the table that one ounce equals 31 grammes; divide 175 by PHYSICS. 27 this, and we have 5.6, the required number of ounces. If we wish to measure 53 Cubic centimetres of any liquid, 53-^29.5, the number of Cubic centimetres in one fluid ounce, 1.8 fluid ounces, the required amount. Converse- ly, suppose we have a quantity of some chemical weigh- ing three-quarters of a pound, and wish to find the metric equivalent. As one pound is equal to 0.453 kilogramme, three-quarters of a pound will be equal to three-quarters of that weight, or 0.33975 f a kilogramme; or, as one kilo- gramme equals IOOO grammes, three-quarters of a pound will equal 339.75 grammes. 1. To convert troy grains into centigrammes, multiply by 6. 2. To convert centigrammes into troy grains, divide by 6. 3. To convert troy grains into milligrammes, multiply by 60. 4. To convert milligrammes to troy grains, divide by 60. 5. To convert troy grains to grammes, or minims into fluidgrammes, divide by 15. 6. To convert grammes into grains, or fluidgrammes into minims, multiply by 15. 7. To convert drachms into grammes, or fluidrachms into fluidgrammes, multiply by 4. 8. To convert grammes into drachms, or fluidgrammes into fluidrachms, divide by 4. (All results approximate). 97. Percentage Solutions. In order to make a percentage solution of a solid in a liquid both should be weighed. A five per cent solution by weight means a solution 100 parts of which contain 95 parts by weight of water to 5 parts by weight of the solid.* *It is a common error to suppose that a five per cent solution is 5 grains of solid to 100 of water. 28 DENTAL CHEMISTRY. Ascertain the weight of a bottle, put into it the proper weight of solid then add liquid enough to make up the final weight. For example, suppose it is required to make a 4 per cent, solution of cocaine hydrochlorate: weight of bot- tle, 400 grains; weight of bottle plus cocaine, 404 grains. It is evident that enough water must now be poured into the bottle, while in the scale-pan, to make the final weight 500 grains. Result, four grains of cocaine in nine- ty-six of water, or a four per cent solution. Examples: supposing weight of bottle to be 400 grains how would a one per cent solution of corrosive sublimate be made? a one in iooo?f a 20 per cent solution of car- bolic acid? Give total weights (bottle included) and the weights of the separate ingredients. Answers: one grain of corrosive sublimate and ninety- nine of water. One grain of the solid and nine hundred and ninety-nine grains of water. 98. Specific Volume. The relative bulks of equal weights of different bodies is their specific volume. Water being taken as a unit, the specific volume of any substance is the volume of a certain weight of it com- pared to that of an equal weight of water at 15 C. (59-6F.). To find ^specific volume, divide the volume of a given weight of the liquid by the volume of an equal weight of water, or divide the specific gravity of water (which is i or 1000) by the specific gravity of the liquid. For example: what is the specific volume of glycerine? IOO grains of glycerine measure 84 minims; 100 grains of fCarefully notice the difference between one in a thousand and one to a thousand. PHYSICS. 29 water measure 105 minims; 84-^105=0.8; or 1000-5-1,250 ( the sp. gr. of glycerine ) =0.8oo, sp. vol. of glycerine. That is, a given weight of glycerine will only measure eight- tenths as much as the same weight of water. 99. To find the volume of a given weight of water in the American system. To change av. oz. of water to fl. oz. multiply by 0.96; tr. oz. of water to fl. oz. multiply by J-OS; grams of water to fl. oz. multiply by 0.0338. Examples: how many fluidounces in 60 avoirdupois ounces of water? how many fluidounces in lotroy ounces of water? how many fluidounces in 20 grams of water? Answers: 60X0.96. 10X1.05. 20X0.0338. 100. To find the volume of a given weight of any liquid. Multiply the volume of an equal weight of water by the specific volume of the liquid; or divide the volume of an equal weight of water by the sp. gr. of the liquid. Examples: how many fluidounces in 200 troy ounces of nitric acid? 200 troy ounces of water are (200X1.05) fluidounces, or 210 fluidounces (see previous rule). 210 multiplied by the specific volume of nitric acid, 0.704, (found by dividing the specific gravity of the water by the specific gravity of the acid, 1.42) will give 147.8, which is number of fluidounces required. 10 1. To find the weight of a given volume of water. Fluido unces to avoirdupois ounces, divide by 0.96; fluidounces to troyounces, di- vide by 1.05; fluidounces to grams, divide by 0.0338. Examples: what is the weight of 13 fluidounces of 30 DENTAL CHEMISTRY. water? of a pint of water? of three pints? (Give answers in both avoirdupois and troy). Answers: 13^-0.96. 13-^-1.05. 16-4-0.96. 16-=- 1.05. Three times the third and fourth answers. 102. To find the weight of a given volume of any liquid. Divide the weight of an equal volume of water by the sp. vol. of the liquid, or multiply the weight of an equal volume of water by the sp. gr. of the liquid. Example: find the weight (troy) of 200 fluidounces of nitric acid of sp. gr. 1.42. The weight troy of 200 fluid- ounces of water is 200-=- 1.05 or 190.4. Divide this by the specific volume of nitric acid, which is 0.704, and we have 270.4, which is the weight required in troy ounces. 103. Thermometrv. The Centigrade ther- mometer has its zero at the freezing point and its boiling point at 100, the number of inter- vening degrees being 100. One degree Centi- grade equals i.8of Fahrenheit. To convert Centigrade to Fahrenheit multiply by 1.8 and add 32. To convert Fahrenheit to Centigrade subtract 32 and multiply by i. Examples: Convert 60 Centigrade to the correspond- ing Fahrenheit. 60 times 1.8 equals 108. The latter plus 32 equals 140. [Turning to the table on page 31, we find 60 C. equals 140 F]. Now find what degree Centi- grade corresponds to 770 Fahrenheit. 770 less 32 equals 738. The latter multiplied by jj-equals 410. [Consulting the table on page 31, we find 770 F equals 410 C.] In general it is easier to consult the table if the latter is at hand when wanted, but as such is not always the case it is advisable to become familiar and ready with the rule. PHYSICS. 31 COMPARISON OF CENTIGRADE AND FAHRENHEIT DEGREES.* Cent. Fahr. Cent. , Fahr. Cent. Fahr. Cent. Fahr. 40 40.0 5 +23.0 +30 +86.0 + 65 +149.0 39 38.2 4 24.8 31 87.8 66 150.8 38 36.4 3 26.6 32 89.6 67 152.6 37 346 2 28.4 33 91.4 68 154.4 36 32.8 1 302 34 93.2 69 156.2 35 31.0 32.0 35 95.0 70 158.0 34 29.2 + 1 33.8 36 96.8 71 159.8 33 27.4 2 35.6 37 98.6 72 161.6 32 25.6 3 37.4 38 100.4 73 163.4 31 23.8 4 39.2 39 102.2 74 165.2 30 22.0 5 41.0 40 104.0 75 167.0 29 20.2 6 42.8 41 105.8 76 168.8 28 18.4 7 44.6 42 107.6 77 170.6 27 16.6 8 46.4 43 109.4 78 172.4 26 14.8 9 48.2 44 111.2 79 174.2 25 13.0 10 50.0 45 113.0 80 176.0 24 11.2 11 51.8 46 114.8 81 177.8 23 9.4 12 53.6 47 116.6 82 179.6 22 7.6 13 55.4 48 118.4 83 181.4 21 5.8 14 57.2 49 120.2 84 183.2 20 4.0 15 59.0 50 122.0 85 1850 19 2.2 16 60.8 51 123.8 86 186.8 18 0.4 17 62.6 52 125.6 87 188.6 17 +1.4 18 64.4 53 127.4 88 190.4 16 3.2 19 66.2 54 129.2 89 192.2 15 5.0 20 680 55 131.0 90 194.0 14 6.8 21 69.8 56 132.8 91 195.8 13 3.6 22 71.6 57 134.6 92 197.6 12 10.4 23 73.4 58 136.4 93 199.4 11 12.2 24 75.2 59 138.2 94 201.2 10 14.0 25 77.0 60 140.0 95 20H.O 9 15.8 26 78.8 61 141.8 96 204.8 8 17.6 27 80.6 62 143.6 97 206.6 7 19.4 28 82.4 -J-63 145.4 98 208.4 6 +21.2 +29 +84.2 64 +147.2 + 99 +210.2 + 100 212.0 110 +230 +210 +410 +310 +590 410 770 120 248 220 428 320 608 420 788 130 266 230 446 330 626 430 806 140 284 240 464 340 644 440 824 150 302 250 482 350 662 450 842 160 320 260 500 360 680 460 860 170 338 270 518 370 698 470 878 180 356 280 536 380 716 480 896 + 190 374 290 564 390 734 490 +914 +200 +392 +300 +572 +400 752 + 500 4 932 +500 +932 +800 1472 +1100 +2012 4-1400 25.52 600 1112 +900 +1652 1200 2192 UOO 2732 +700 +1292 +1000 +1832 +1300 +2372 + K>00 +2912 *Barker. 32 DENTAL CHEMISTRY. CHAPTER II. CHEMICAL PHILOSOPHY. 104. Chemistry defined. Chemistry is the science which studies the properties, constitu- tion, and laws of composition of bodies, whether crystalline, volatile, natural, or artificial. 105. Field of chemistry. Chemistry studies such properties of matter as result from its atomic composition. Chemical PhilosopJiy treats of the general facts of chemistry, the general laws deduced from these facts, and the operations which lead to a knowledge of the internal composition of matter. It comprises and classifies our knowl- edge of those phenomena which imply a change of substance. Special Chemistry studies the character and properties of certain definite bodies, and shows in what manner they are governed by the laws of general chemistry, or chemi- cal philosophy, 106. Analysis and Synthesis. Chemical analysis is an operation by which the composi- tion of matter is ascertained by splitting up a substance and separating its constituents from CHEMICAL PHILOSOPHY. 33 one another. Synthesis is an operation by which simple bodies are combined to form compound ones, or compounds combined to form complex ones. 107. Definitions Molecule, Atom, Element, Com- pound. Matter or substance is the general term given to that which has length, breadth, and thickness. Any por- tion of matter which we perceive by the senses is called a mass of matter. Every mass of matter consists of molecules. A Molecule is the smallest particle into which any sub- stance can be divided without losing its identity as that substance. The smallest particle into which common salt can be divided and still be salt and nothing but salt, is termed a molecule of salt. The smallest particle of iron which can exist free, that is, uncombined with anything else, is called a molecule of iron. Molecules are too small to be seen even with the aid of the most powerful microscope. Their existence, however, is now very gener- ally admitted, as we are able to account for numerous phenomena if we assume that molecules exist. When a substance loses its identity, its molecules split up into small particles called atoms, which, however, have an at- traction for one another and tend to form new molecules by coming together in groups. Thus, the molecule of mercuric oxide is composed of an atom of mercury com- bined with an atom of oxygen; when this substance is heated, its molecules break up, and the substance is no longer the oxide of mercury, but mercury and oxygen. When the molecules of oxide of mercury split up, the constituent atoms re-arrange themselves, those of the mercury forming molecules of mercury, and those of oxy- gen molecules of oxygen. The molecule, then, is composed of atoms, held to- gether by a certain attraction called by some chemism, by 34 DENTAL CHEMISTRY. others chemical affinity. Each atom has an attractive power for other atoms, which is definite in quantity but neutralized when a sufficient number of other atoms ap- proach it. Definition i. A molecule is the smallest particle of any substance which can exist by itself and, remain free and uncombined. Mole- cules are destructible and divisible. Definition 2. An atom is the still smaller particle entering into the composition of the molecule. Atoms cannot, in all probability, re- main free and uncombined; they are indestruc- tible and indivisible. It follows from definition 2, that matter is indestructible. Definition 3. Element: a substance whose molecules are composed of the same kind of atoms, as the molecules of gold; the molecules of any substance in Table i are composed of atoms of that substance, and of nothing else. Definition 4. Compound: a substance whose molecules are composed of different kinds of atoms. The molecule of salt is not composed of atoms of sodium alone, nor of chlorine alone, but of an atom of sodium and an atom of chlorine. Definition 5. Mixture: two or more sub- stances form a Mixture when the particles of one are scattered throughout those of the other or others, without any change taking place in CHEMICAL PHILOSOPHY. 35 the chemical or specific properties of one or the other. Example: sand and sugar. 1 08. Law of Avogadro. Equal volumes of all bodies in the state of gas and at the same temperature and pressure contain the same number of molecules. Therefore (a) the mole- cules of all bodies in the gaseous state are of the same size and (d) the weight of any mole- cule, as compared with that of hydrogen, is in proportion to the weight of any volume given, as compared with the same volume of hydro- gen. 109. How to determine the number of atoms in the hydrogen molecule. Suppose a given volume of hydro- gen contains 10,000,000 molecules; byAvogadro's law the same volume of chlorine will contain 10,000,000 mole- cules. Combined, they form two volumes of hydrochloric acid gas which will necessarily contain 20,000,000 mole- cules. Analysis shows each molecule of hydrochloric acid gas to consist of two atoms, one of hydrogen and one of chlorine, that is, the 2O,OOC,OOO molecules of hydro- chloric acid gas will contain 20,OOO,OOO atoms of hydro- gen and 20,000,000 of chlorine. Now there were but 10,- OOO.OOO molecules of hydrogen in the start, before com- bination, therefore each molecule of hydrogen must have contributed two atoms of hydrogen. So also with the chlorine. From this it follows that there are two atoms in every molecule of hydrogen; and the weight of the atom (atomic weight) of hydrogen being taken as i.the weight of its molecule (molecular weight) will be 2. 1 10. Symbols. Chemists designate each element by an abbreviation called a Symbol, 36 DENTAL CHEMISTRY. which is often the first letter or first two letters of its Latin name. Thus the symbol for potassium is K (Latin Kaliuni] that of gold Au ( Latin Aurum}. A symbol not only designates an element but just one atom of that element having a definite weight (atomic weight). Thus O not only signifies oxygen, but one atom of oxy- gen, or 16 parts by weight of oxygen. The symbols of the elements with the atomic weights, specific gravity, specific heat, and melting point are now shown by Table i. The beginner should pay particular attention to those elements printed in large type. Note that the metals, as a rule, are positive to hydrogen, while the non-metals* are negative to it. Observe that hydrates of elements at the positive end form bases, while hydrates of those at the negative end form acids. Table I is that of Professor W. H. Seaman, M. D. The atomic weights are from the "Laboratory Yearbook" of Professor John Howard Appleton, as are also forty of the figures of specific gravity. f *Antimony resembles metals in physical properties not chemical. fThe forty are those of Li, K. Na, Cl, Ca, Mg, P, S, Gl, C, Si, Al, Sr, Br, I, As, Te, Sb, Cr, Zn. Sn. Fe, Mn, Co, Ni, Cd, Mo, Cu, Bi, Ag, Rh, Pb. Pd, Hg, W, U, Au, Pt, Ir. Those who intend to pursue the study of chemistry more in detail will do well to read Lothar Meyer's work on Theoretical Chemistry, or Remsen's book entitled "The Principles of Theoretical Chemistry." Among other works on chemistry of general value are those of Beilstein, Roscoe, and Schorlemmer, Jungfleisch. For an elementary work, Nichol's "Abridgment" of Eliot and Strer is satisfactory; the beginner will find the appendix valuable in its instructions about chemical manipulations. Table I. CONSTANTS OF THE ELEMENTS. ( Arranged by Prof. Seaman.) ELECTRO-CHEMICAL SERIES. 37 Positive end: hydrates form bases. SYMBOLS. Approx wghts. Specifiegravity (Water=l) Specific Heat. Melting Point. Centigrade 'erissad Artiad. NAME. Cs Rb K Na Li Y E Al D La Ga Tl In Bi Ag Au H Cb Ta Sb B V As P I Br Cl F N Ba Sr Ca a Zr Th Ce Mn Zn Fe Ni Co Cd Pb Sn U Cu Pd Ru Rh Pt Ir Os Si Ti Te C W Mo Cr Se S 132.5830 85 2510 39.0190 22.990 7.U073 136.7630 87.3.40 39.9900 23.9590 9.0850 89.8160 165.8910 27.0090 '9.3070 233.4140 140.4240 1 44.5730 138.5260 53.9060 68.8540 64.9045 55.9130 57.9280 58.8870 203.7150 111.8350 206.4710 113.3980 117.6980 207.5230 238.4820 63.1730 107.6750 199.71-20 105.7370 104.2170 104.0550 194.4150 19?.6510 198.4940 196.1550 1.0000 28.1950 47.9997 93.8120 182.1440 127.9600 119.9550 11.9736 10.9410 183.6100 95.5270 51.2560 52.0090 74.9180 30.9580 78.7970 126,5570 79.7680 35.3700 18.9840 14.0210 31.9840 15.9638 132.6 85.3 39.0 23.0 7.0 136.8 87.4 40.0 24.0 9.1 89.8 165.9 27.0 89.4 233.4 140.4 144.6 138.5 63.9 68.9 4.9 55 9 57.9 58.9 203.7 111.8 206.5 113.4 117.7 207.5 23S.5 63.2 107.7 199.7 105.7 104.2 1041 194.4 192.7 198.5 196.2 1.0 28.2 48.0 93.8 182.1 128.0 120.0 12.0 10.9 183.6 95.5 51.3 52.0 74.9 31.0 78.8 1266 79.8 354 19.0 14.0 32.0 16.0 1.88 1.52 0.86 0.97 0.59 4.00 2.54 1.M 1.70 to 1.74 2.10 4.80 2 50 to 2.67 4.10 7.90 6.62 6.40 6.10 8.01 to 8.03 6.00 7.10 to 7.20 7. 79 to 7.84 8.60 to 8.82 8.49 to 8.51 11.80 8.45 to 8.69 11.33 toll.39 7.40 7.30 980 18.40 8.93 to 8.95 10 40 tolO.57 13.60 11.80 11.40 11.00 toll.20 21.50 21.80 22.40 19.26 to!9.34 2.49 7.10 10.78 6.18 to 6.24 6.72 2.27 to 3.52 2.63 17. 20 to 18.30 8.62 to 8.64 5.50 7.01 5.63 to 5.67 1.83 to 1.96 4.28 to 4.80 4.95 2.99 to 3.19 1.33 (liquid) 1.98 to 2 07 0.1695 0.2934 0.9408 0.2499 0.2143 0.1217 0.0955 0.1138 0.1086 0.1069 0.0338 0.0556 0.0314 0.0562 0.0308 0.0619 0.09ol 0.0570 0.0319 0.0592 0.0562 0.0324 0.0325 0.0311 0.0324 3.4090 0.1774 0.0473 0.0557 0.1468 to 0.2415 0.2500 0.0334 0.0721 0.0814 0.1887 0.0746 0.0541 0.0813 0.1210 2438 0.1776 0.2175 26.5 e 37.0 62.5 97.0 180.0 425.0 412.0 2000.0 2000.0 1670.0 294.0 315.0 325.0 230.0 264.0 1200.0 1000.0 40.0 High 3000 1000 1250 450 nearly inf. High 3000 44 100 to217 107 POTASSIUM (Kalium) SODIUM (Natron) LITHIUM BARIUM STRONTIUM CALCIUM . . .. MAGNESIUM Glucinum (Beryllium, Be)... Erbium ALUMINIUM Zirconium CERIUM Didvmium Lanthanum MANGANESIUM Gallium ZINC IRON (Ferrum) NICKEL COBALT Thallium CADMIUM LEAD ( Plumbum) Indium TIN (Stannum) BISMUTH Uranium COPPER (Cuprum) SILVER (Argentum) MERCURY (Hydrargyrum) Palladium Rhodium PLATINUM Iridium Osmium GOLD (Aurum >... HYDROGEN . SILICON Titanium Columbium (Niobium Nb)... Tantalum Tellurium ANTIMONY (Stibium) CARBON BORON Wolfram (Tungsten) . . . olybdenum Vanadium CHROMIUM .. ARSENICUM PHOSPHORUS Selenium IODINE .. BROMINE CHLORINE Fluorine NITROGEN.., SULPHUR.. OXYGEN NEGATIVE END: hydrates form acids. 38 DENTAL CHEMISTRY. Such elements as neptunium, davyum, phillipium. deci- pium, etc., etc., are of no importance to the dentist- Moreover, Crookes, in his address to the Chemical So- ciety of Great Britain, has questioned the elementary character of the so-called rare earths and proposes the term "meta-elements" for those substances which are neither compounds, mixtures, nor elements. in. Number of Atoms in Molecules of Elements. At ordinary temperatures most of the elements given in Table I contain two atoms in the molecule and are called, therefore, Diatomic. Exceptions: mercury, cadmium, zinc, barium are Monatomic, i. e., have one atom in the molecule; ozone contains three atoms of oxygen; the molecule of phosphorus and of arsenic contains four atoms; that of sulphur, six, but at high temperatures, two. Elemental Atoms and Molecules. The symbols given in Table I should not be used to represent the ele- ments in general; each symbol represents one atom of the element; thus, Zn does not represent zinc in general, but one atom of the element zinc with the properties of that atom, namely, definite unchanging weight and defi- nite power of attraction for other atoms. Rule 1. To Denote a Number of Atoms of an Element, write the Symbol of the Ele- ment with the required number in Arabic Figures at the lower right hand corner of the Symbol. Zn 2 means two atoms of zinc; H 3 means three atoms of hydrogen; O 4 means four atoms of oxygen. Where one atom of an element is to be represented, write the symbol only. Rule 2. To Denote a Molecule of an Ele- meiit, write the Symbol of that Element with CHEMICAL PHILOSOPHY. 39 the Figure 2 at its lower right hand cor- ner. Exceptions: write the symbols only of mercury, cadmium, zinc, and barium; write four after the symbols of phosphorus and arsenic, and six after sulphur. O 2 means one molecule of oxygen, composed of two atoms. Hg means one molecule of mercury, composed of one atom; P 4 means one molecule of phos- phorus, composed of four atoms; S 6 means one molecule of sulphur, composed of six atoms. (See in for Atomicity), Rule 3. To Denote a Number of Molecules of an Element, write the required Number as a full sized Figure before the expression for one Molecule. 2O 2 means two molecules of oxygen, each composed of two atoms. 2Zn means two molecules of zinc, each composed of one atom. 112. Atomic weight. The atomic weight of an element denotes the weight of an atom of it referred to the weight of an atom of hy- drogen as unity. The proportions in which atoms combine also represent the weights of the atoms: thus, oxygen unites with other elements in proportions of 16, therefore 16 is the weight of the atom of oxygen. 113. Determination of atomic weight. By quanti- tative analysis the weights of two elementary substances forming a compound is ascertained. The proportion of these weights, one to another, will be either the ratio of the atomic weights of the two elements, or else that 40 DENTAL CHEMISTRY. of some simple multiple, the latter being previously known from a comparison of the compounds of the element whose weight we are seeking. Thus, suppose it is desired to find the atomic weight of zinc. Suppose that on using a given weight of zinc and of hydrochloric acid a certain volume of hydrogen is evolved. Make a proportion: Weight of hydrogen found: weight of zinc used = i: x. Now x will be either the atomic weight of zinc, or some multiple of it. From a comparison of the numerous zinc compounds we know the result obtained to be half the atomic weight. Double the value to find the accepted weight. 114. Quality of Combining Power of Atoms. Positive and Negative Elements. When a current of electricity of sufficient strength is passed through a chemical com- pound in state of solution, /'. 2 or (SnOs) 2, that is two molecules of Sn 2 . 50 DENTAL CHEMISTRY each other instead of requiring two bonds of chlorine; the other two bonds of the mercury are satisfied by means of two chlorine bonds, hence Hg 2 C1 2 , and not C1 4 as might be expected. The same may be said of copper. Such compounds are called mercurous or cuprous compounds. Variation in equivalence may, in general, be explained by- graphic formulae. Rule 8. To write formulae containing mercury or copper, assign to mercuric atoms and cufiric atoms an equivalence of two as in table 4; to mercurous and cuprous assign an equivalence of one. N. B. In the case of mer- curous and cuprous note that two atoms of mercury or copper require two only of a unival- ent element. Example 5. Write the formulae for mercuric chloride, mercurous iodide, cupric oxide, mercurous chloride. Answers. HgCl 2 , Hgl or Hg.,L, CuO, HgCl or Hg 2 Cl 2 . Compounds of iron are known to exist in which the molecule may consist of two atoms of iron and six of a monad, as for example, ferric chloride, Fe 8 Cl 6 ; to such compounds the term ferric is applied. Rule Q. To write formulae containing mw,give two atoms of iron together, an equiva- lence of six, if the compound is called ferric. In ferrozis compounds assign equivalence of fao to iron. N. B. While Hg 2 Cl 2 is often written in the simpler form HgCl, it is not customary to write Fe 2 Cl 6 in any simpler fashion; the formulae of other compounds are usually sim- plified. Example 6. Write the formulae for ferric chloride, fer- ric oxide, ferrous sulphide, ferrous oxide, aluminic chloride. CHEMICAL PHILOSOPHY. Answers. Fe 2 Cl 6 , Fe 2 O 3 , [that is (Fe 2 ) 2 O 6 ], FeS, FeO, A1 2 C1 6 like ferric. Rule 10. To read Binary Formulae, ob- serve from figure at lower right hand of nega- tive element what the equivalence of the posi- tive element is. If the positive element is in its highest equivalence (Table 3) change its termination to-ic etc., as in Rule 6. Note that where sulphur is the positive element and the negative element oxygen, the figure 3 at the lower right hand of oxygen will denote sul- phur as a hexad, hence sulphur/*: : e. g., S 2 O 6 or SO 3 is sulphur/^ oxide. In reading binary formulae, the termination of the nega- tive element is always changed to -ide. Example 7. Read the formulas of the following com- pounds used in dental medicine: i, KBr. 2, KI, 3, HC1. 4, SnCl 2 . 5, KC1. 6, K 2 O. 7, H 2 O. 8, A1,C1 6 . 9, As 2 O 3 . 10 AuCl 3 . u, HgCl 2 . 12, HgCl. 13, Hgl. 14, Znl g . 15, ZnO. 16, MgO. 17, CaO. Answers. I, potassium bromide. 2, potassium iodide, 3, hydrogen chloride. 4, stannous chloride. 5, potas- sium chloride. 6, potassium oxide. 7, hydrogen oxide. 8, aluminic chloride. 9, arsenous oxide. lo, auric chlo- ride. II, mercuric chloride. 12, mercurous chloride (see Rule 8). 13, mercurous iodide. 14, zinc iodide. 15, zinc oxide. 16, magnesium oxide. 17, calcium oxide. Example 8. Read the following formula:; (of use in studying ternaries): C1 2 O 5 , N 2 O 5 , SO 3 , SO, C1 2 O, C1 2 O 3 , C0 2 . Answers. ' Chloric oxide, nitric oxide, sulphuric oxide, 52 DENTAL CHEMISTRY. hyposulphurous oxide, hypochlorous oxide, chlorous oxide, carbonic oxide. 126. Radicals. A radical is an unsaturated group of atoms. It possesses free bonds, hence may enter into combination like single atoms. Example: HO is an unsaturated group of atoms, for one bond of the oxygen is unprovided for, thus, H O . Hence HO is a radical. 127. Nomenclature, and equivalence of radicals.-The names of compound radicals end in -yl. Thus, HO is called hydroxyl. The equivalence of compound radicals is al- ways equal to the number of unsatisfied bonds, that is to the difference resulting from the sub- traction of the equivalence of one of its con- stituents from that of the other: Thus the equivalence of HO is one because it has one unsatisfied bond, that is, 2 (equivalence of oxygen) minus I (equivalence of hydrogen) equals I (equivalence of hydroxyl). Radicals are therefore perissad and artiad like atoms. Perissad radicals can not exist free except by combining with one another. 128. Ternary Compounds. Definition 7. A ternary compound is one whose molecule is composed of three or more different kinds of atoms: thus, KC1O 3 is a ter- nary because composed of K, Cl, and O. In every ternary formula there are at least three different symbols. In ternaries the dissimilar atoms are linked together CHEMICAL PHILOSOPHY. 63 by a third atom, and ternaries are of two classes, (a) those whose dissimilar atoms are linked by a bivalent atom, and (b} those whose dissimilar atoms are linked by a trivalent atom. The first class comprises many inor- ganic compounds, the second many organic. In the first class the linking is usually performed by oxygen, sometimes by sulphur, sometimes by selenium and tellurium. 129. Ternaries of the first class. Dissim- ilar atoms linked by oxygen or sulphur. There are three kinds: acids, bases, and salts. Definition 8.' Acids are corrosive substances having- usually a sour taste, neutralizing alka- lies, and changing blue vegetable colors to red. They give off hydrogen when brought into contact with a metal. Acids are either (hydracids), ox-acids, or sulpho-acids. [Hy- dracids are binary compounds of hydrogen, and are hydrochloric, HC1; hydrobromic, HBr; hydriodic, HI; hydrosulphuric, H 2 S. They are also called hydrogen (or hydric) chloride, hydrogen or hydric bromide, etc.]. Ox-acids are composed of hydrogen, some negative element, and oxygen: as HNO 3 , nitric acid. Sulpho-acids are composed of hydrogen, some negative element, and sulphur, as H 2 CS 3> sulpho-carbonic acid. 54 DENTAL CHEMISTRY. Rule ii. To write the formulae of many ox-acids and sulpho-acids:* 1. Write the formula of corresponding ox- ide or sulphide, simplifying if possible. 2. Add formula for a molecule of water, H 2 O, in case of an ox-acid, or H 2 S in case of a sulpho-acid. 3. Simplify if possible. Suppose the formula for nitric acid be re- quired: first write the formula for the corre- sponding* oxide. By this we mean m'tricf oxide and not nitrous or hyponitrous. For- mula for nitric oxide is N 2 O 5 ; add H 2 O and we have H 2 N,O 6 the only thing to be added arithmetically being O to O 5 making O 6 . Now simplify by taking out the common factor 2 and we have HNO 3 . (See also Table 4 and note Rule 14, page 58). *Rule 11 is deduced from the following: 1. An acid molecule is one consisting of one or more negative atoms united by oxygen to hydrogen. 2. Ternaries are formed by the direct union of the oxide of a more positive atom with the oxide of a less positive or negative atom. Whenever water is the positive oxide, the body produced is an acid: thus, of the two oxides, sulphuric and hydric, sulphuric oxide is the negative and hydric oxide (water) the positive, there- fore the two on combining form an acid. 3. An acid, then, may be formed by the combination of a nega- tive oxide with water. Acids are also formed from water, H O H, by exchanging an atom of H for a negative monad. Thus, hypochlorous acid: ex- change one atom of H for Cl and there is formed Cl O H. jThis rule gives always hydrated acids and is of service in obtain- ing formulae of salts. The use of Table 4 is to be preferred. CHEMICAL PHILOSOPHY. 55 Note. The formulae for phosphoric, boric, arsenic, arsenous, and hypophosphorous acids are obtained by adding more than one molecule of water or (better) by Table 4, page 58. Example 9. Write the formulas for the following acids: sulpho-carbonic, sulphuric, sulphurous, hypochlorous, ni- trous. Answers: H 2 CS 3 , H 2 SO 4 , H 2 SO 3 , HC1O, HNO g . N. B. The oxygen or sulphur of acids is said to have a linking function, uniting the hydrogen to the rest of the molecule; thus, the formula for nitric acid may be repre- sented graphically as follows: H O N=O j the hydrogen atom being linked to the =O ( rest of the molecule by the oxygen atom. Definition 9. Bases are the opposite of acids. They neutralize acids, either partly or entirely, restore blue colors to vegetable colors turned red by acids, when concentrated decom- pose fats, forming- soap, and act on the tissues as caustics. Acids unite with metals to form salts, bases with acids to form salts, hydrogen being evolved in the one case, water formed in the other. Inorganic bases are termed hydrates, by which term we shall hereafter call them. The molecule of a hydrate is composed of a posi- tive atom or atoms, hydrogen, and oxygen: thus, R O H. R denoting any number of positive atoms. The oxygen of bases is said to link the hy- drogen to the positive element. 56 DENTAL CHEMISTRY. The formula for sodium hydrate may be represented graphically as follows: Na O H, in which the positive atom is linked by the atom of oxygen to the hydrogen. Rule 12. To write the formula for a hy- drate, first write the symbol of the positive element with its equivalence over it, then write OH in brackets with an equivalence of i over it. Next exchange figures representing equiva- lences, as in binaries.* To write the formula for calcium hydrate: 1. Ca 11 . 2. (OH) 1 . 3. Ca n (OH) r . 4. Ca(OH) 2 . Calcium hydrate. Calcium hydrate represented graphically would be r /OH Ca \OH. Example 10. Write the formulae for barium hydrate, mercuric hydrate, arsenous hydrate, cuprous hydrate. Answers. Ba(OH) 2 , Hg (OH) 2 , As(OH) 3 , CuOH. N. B. Where one molecule only of OH occurs it is not necessary to bracket. Instead of OH some authors write HO. Definition 10. A salt resembles neither an *Rule 12 is deduced from the following: a molecule of water con- sists of two atoms of hydrogen linked by oxygen. Exchange one of these hydrogen atoms for a positive univalent atom, and a base re- sults. Thus, water is H O H: exchange H for K and we have K O H. But when it is necessary to form the hydrate of a bival- ent atom it is necessary to take two molecules of water and one of the bivalent element. Thus, if calcium hydrate be required, take 2 HsO, or H^Os. Substitute Ca for Ha and we have CaHaOz or Ca(HO), The formulae of bases may be obtained also by direct union of water with a positive oxide. CHEMICAL PHILOSOPHY. 57 acid nor a base; its molecule consists of a pos- itive atom united by oxygen to a negative atom; thus, KNO 3 : K positive atom, N nega- tive, O oxygen. Exceptions. A salt may be formed from an acid and a metal, the latter replacing all the hydrogen of the acid; acids whose molecule contains two atoms of hydrogen may not always exchange both atoms for atoms of a metal, but one may be replaced and the other not: thus, NaHSO 4 . Such a salt is called an acid salt. Those described in Defi- nition 10 are called normal salts. Double salts are those whose molecules consist of two, different, positive atoms united by oxygen to the negative atom: thus, KNaSO 4 , called potassium sodium sulphate, or the double sulphate of potassium and sodium. Rule 13.* To write the formula of a salt. First write the formula of the acid which, with the metal, forms the salt; bracket the non-hydrogen part of the acid formula, erase the H, and put in its place the symbol of the metal ; write the equivalence of the metal after the bracket, and simplify if possible. Note that -ate in a salt corresponds to -ic in an acid, -ite to -otis, hypo-ite to hypo-ous. Examples: sodium sulphate is formed from sulphunV acid, sodium sulphite from sulphur^z/^ acid, sodium hypo- chlorite from hypochlor Cu 2 FeCy 6 , BaCrO,, PbSO,, Fe 2 (S0 4 ) 3 , Fe 2 (PH 2 2 ) 6 , A1 2 (HO) 6 , FeSO 4 , 9- 10. ii. 12. 13- Na(PH 2 O 2 ), KC1O, Ca(ClO) 2) KNaSO 4 , KNaHP0 4 , NaHC0 3 . TERNARIES OF THE SECOND CLASS. DISSIM- ILAR ATOMS LINKED BY TRIADS. 130. Ternaries of the second class are linked mostly by nitrogen. There are three kinds of those linked by nitrogen '.-amides ^\ whose mole- cule negative atoms are linked to hydrogen by nitrogen, C t- ? B 9.08 109 c Na 11 97 n 14 01 TT 22.99 i\,f 1 S Qfi Mg Al 19.06 23.94 9T ni Si p K 28 30.96 Cl Ca 31.98 QfC Q7 be Ti 40 07 v Cu 48 <~ r 51.1 Mn 6.}. 18 Zn 52.45 K.i ft Fe Co Ni Ua rv r r") 88 58 6 58 6 (; times a better conductor than zinc. But zinc is 4th in rank among the twelve, for only three are better conductors of electricity. Resistance to air, etc: resistance to dry, pure air is one thing, but resistance to air containing moisture, carbonic ackl, etc., is quite another. Under this head also, is mentioned the effect of sulphuretted hydrogen on the metal. Solubility: under this head the best solvents for the metal are given, that is, substances having the power, like acids, to attack the metal and convert it into a liquid. Direct combinations: under this heading is given a list of substances which unite directly with the metal, either in the cold or when heated, rubbed, or triturated with it, without the intervention of oxygen. Structure: many of the metals have a crystalline struc- ture, i. e., when small particles of them are seen under the microscope, certain definite geometrical shapes are ob- served as cubes, rhombohedrons, etc. The form in which iron tends to crystallize is a regular octahedron: an eight- sided figure with equal axes at right angles to one an- other. Crystalline forms are classified into six systems. (See Chap. I). Many of the metals are to be found in the first or isometric system, in which there are three axes of equal length, and at right angles to each other, as in case of the cube and the octahedron. Copper crystals are examples of the isometric system. Compounds: the metals form various compounds ac- CHEMICAL PHILOSOPHY. 85 cording to their equivalence, and Latin names are often used instead of English: for example, iron as a dyad, uniting with other elements, forms ferrous compounds; sil- ver compounds are sometimes called argentic, as argentic nitrate, etc., etc. TABLE No. 9 NAMES AND PROPERTIES OF THE MORE IMPORTANT METALS. Names. Sp. gr. Fusing Point; approximate Fahrenheit. Weight of One Cubic Foot in Pounds. Tensile Str'gth per sq inch in tons. *Aluminium 2.67 1292 120 Antimony 6 72 1150 419 5 5 Bismuth 9.80 507 613 1 5 *Cadmium 8.69 442 542 5 *Cobalt 8.51 less than iron 558 7 same as iron *Copper 8.95 1996 558 1 13 to 15 *Gold 19.34 2016 1208 6 9 1 *Iron 7.84 3500 489 4 29 (maximum) Lead 11.36 617 709.2 08 to 1.5 Magnesium Manganese 1.74 8.01 850 less than iron 108.6 5000 Mercury 13.59 39 8484 "Nickel 8.67 less than iron 641.2 same as iron *Palladium 11.8 same as ircn 736.6 *Platinum 21.58 greater than iron 1344.0 Silver 10.53 1873 657.3 18.2 Tin 7.30 442" 455.1 2 to 3 5 *Zinc 7.14 773 445.7 3.3 to 8 3 N. B. The star* refers to the wrought metal. Mercury, tin, cad- mium, bismuth, lead, and zinc, are all fusible below red heat. Anti- mony, just below red heat. Silver, copper, gold, and aluminium, at bright red heat. Iron, cobalt, manganese, and palladium, at highest forge heat. Osmium, iridium, platinum, at heat of oxy-hydrogen blowpipe. Steel is to be melted in a furnace of special construction, called a wind furnace. 86 DENTAL CHEMISTRY. TABLE No. 10 TENACITY, RELATIVE MALLEABILITY, AND DUCTILITY OF THE MORE IMPORTANT METALS. Name. Tenacity. Malleability. Ductility. Lead 1.00 6 10 Cadmium 1.20 Tin 1.33 4 9 Zinc 2.00 7 8 Palladium 11.50 (:o) 6 Gold 12.00 i 1 Silver 12.50 2 2 Platinum.. 15.00 5 3 Copper. 18.00 3 5 Iron 27.50 8 4 Steel 42.00 Aluminium 7 Explanation: tenacity: if the weight required to pull asunder a wire of lead be taken as a standard and called I, the weight required to pull asunder a wire of cadmium would be a little more, namely 1.2; that to pull asunder a wire of steel, for example, 42 times as much as the lead. Malleability: if the difficulty with which a mass of gold can be hammered or rolled into a thin sheet, without being torn, be represented by I, iron will be found to be 8 times as difficult. Ductility: if the difficulty with which gold can be drawn into a wire be represented by I, tin, for example, will be drawn with 9 times the difficulty. TABLE No. 11 CONDUCTING POWERS OF METALS. Name. Heat. Electricity. Silver. 1 1000, (standard). Gold 2 779, (3d). Copper . 3 999, (2d) Aluminium . ... 4 Zinc 5 290, (4th). 6 168, (7th). Tin 7 123, (9th). 8 180, (6th). Lead . 9 83, (10th). Antimony 10 4fi, (llth). Bismuth 11 12, (12th). Palladium. 184, (5th). Nickel 131, (8th). CHEMICAL PHILOSOPHY. 87 Explanation: in the table under heat, the metals are arranged in the order of their conducting power, silver being the best conductor, gold next, etc., etc. In the ta- ble under electricity, silver is taken as the standard, as it is the best conductor of electricity, and the other metals are compared with it, in the pure state at 32 F. In some works gold is given 3d place in heat-conducting power, copper 2nd. Properties of metals and uses: mercury is useful for amalgamating or dissolving other metals; antimony has the property of hardening lead and tin, when melted with them; bismuth and cadmium make tin capable of being melted at lower temperatures; nickel whitens cop- per, and is used in the manufacture of German silver. Gold, platinum, palladium, silver are limited in use by their high price, and the same is true to a certain extent of aluminium, although the price of this metal is lower now than formerly. Zinc has a comparatively high degree of expansibility; gold is the most malleable of metals as also the most ductile; silver is the best con- ductor of heat and electricity; the tenacity of metals is usually diminished by heating; malleability and ductility are developed in some metals by heating, but impaired by carrying heat too far; in alloys, heating impairs tenac- ity, malleability, and ductility; crystalline metals, as bis- muth, lack malleability, etc.; metals may be obtained in crystalline form by electrolysis, either by introducing other metals in strips or rods into their solutions, as a rod of zinc into a solution of a lead salt, or by passage of a weak electric current through their solutions. Gold may be obtained in crystalline form by introduction of a stick of phosphorus into a solution of one of its salts. 158. General properties of alloys of the metallic elements. Alloy is the name given 88 DENTAL CHEMISTRY. to a combination obtained by fusing metals to- gether. Alloys are, as a rule, chemical com- pounds dissolved in excess of one of the constituent metals, but many are merely me- chanical mixtures, or molecitlar mixtures, as the term is. All alloys exhibit the metallic na- ture in their physical characteristics. As regards specific grayity, an alloy of gold and silver is lighter than the theoretical mean of its constituents; brass, and an alloy of lead and tin, heavier; in other words, the gold and silver alloy is formed by expansion, the latter by contraction. In the formation of some al- loys there is no change in volume. In color, alloys are usually gray, unless there is sufficient copper or gold to impart the characteristic color of those metals. Alloys are usually harder and more brittle, less ductile and less tenacious, than the constituent metal exhibiting these qualities in the highest degree; aluminium bronze is an exception, its tenacity being greater than that of either of the constituent metals. The fusibility of an alloy is generally greater, i. e., the alloy melts more readily than that of the least fusible constituent metal and sometimes than that of any con- stituent metal.* An alloy heated gradually to near its fusing point undergoes a change; its constituents reunite to form a mass now fusible; if the fluid be poured off, a solid alloy is obtained less fusible than the original. In this way copper is separated from silver. An alloy of zinc or of mercury is decomposed by heat, but at a higher temperature than the point of ebullition of the metal. As regards temperature, an alloy of 94 copper to 6 tin, if slow- ly cooled, becomes brittle, but, if cooled rapidly with cold *Thus, tin unites with gold far below the melting point of gold. CHEMICAL PHILOSOPHY. 89 water, malleable. Mercury, bismuth, tin, and cadmium give fusibility to alloys, tin hardness and tenacity, lead and iron hardness, antimony and arsenic brittleness. Metals are usually fused under a layer of charcoal to pre- vent oxidation; they are mixed by agitation and allowed to cool slowly. Certain peculiarities of alloys as to solubility must be noticed: platinum is insoluble in nitric acid, but an alloy of platinum with silver or gold is soluble in the acid. Sil- ver is readily soluble in nitric acid, but an alloy of silver with 25 per cent, gold is insoluble. The affinity of an alloy for oxygen is greater than that of the separate metals, but the action of air is in general less on alloys than on the separate metals composing them, with some exceptions. Some difficulty is occasionally experienced in obtaining a perfectly uniform alloy, on account of the different specific gravities of the metals composing it each metal assuming the level due to its specific gravity. This result is not so likely to occur, when the metals employed are in small quantities, briskly stirred, and suddenly cooled. In alloying three or more metals differing greatly in fusi- bility, or that have but little affinity for one another, it is better to unite first those that most readily combine, and then this combination with the remaining metal or met- als. If, for example, it is desired to unite a small quan- tity of lead with brass or bronze, some difficulty would be experienced in forming the alloy by direct incorporation of the metals, but union could be readily effected by first melting the lead with zinc or tin, and then adding the melted copper. Alloys consisting of two metals, one readily oxidiza- bie, the other possessing less affinity for oxygen, may foe readily decomposed by the combined action of heat and air. 90 DENTAL CHEMISTRY. 159. Solders: it is often necessary to unite several pieces of the same metal, or of differ- ent metals. For such work a kind of alloy called solder is used. Solders usually contain the metal on which they are to be used, to- gether with some other metal or metals, which shall reduce the fusing point without affecting the color. [A solder suitable for use in prosthetic dentistry should fuse at a much lower temperature than the plate upon which it is to be used. Its color should be as nearly as possible the same, and it should withstand the action of the fluids of the mouth nearly as well. These properties may be obtained by the addition of small amounts of sil- ver, copper, or brass. (Essig.)]. Solders have been divided into two classes: (a] solders made by the fusion of the metal itself, without others, and (b] solders made on a metal with another metal; or by an alloy applied to the surfaces which are to be united. In the last case the metal or alloy must be more fusible than the metal to be soldered, and have a more powerful chemical affinity for it. Hard solder is used for metals difficult to melt, soft sol- der for those not so difficult. 1 60. General properties of the non-metallic ele- ments. It is difficult to draw a sharp line between met- als and metalloids, but as a general rule those that are not gaseous at ordinary temperatures have no metallic lustre, are of low specific gravity, neither malleable nor ductile, conduct heat and electricity very imperfectly. The nitrogen group, N, P, As, Sb, and Bi is remarkable for a change from non-metallic properties to metallic as the atomic weight increases, beginning with nitrogen, atomic weight 14 and gaseous, and ending with bismuth, 210, CHEMICAL PHILOSOPHY. 91 which has well-marked metallic properties. Arsenic is a metalloid with strongly metallic characteristics, uniting with chlorine like a basic metal, but on the other hand uniting with oxygen to form anhydrides. 161. Classification according to valence. Owing to the didactic character of this book those elements of im- portance to the dentist will be studied in such a way as to keep their valence and electro-chemical relations constantly in view.* Table I of Professor Seamanf will be taken as a basis for the classification. *Those interested in the further study of theoretical chemistry should procure Lothar Meyer's "Modern Theories of Chemistry" translated by Bedson and Williams. fProfessor Seaman divides, for didactic purposes, the elements as follows: A. Gases: O, H, N, Cl, F. B. Halogens: I, Br, Cl. C. Metals: As, Sb, Fe, etc. [Sub-classes of metals: metals of the alkalies, Na, K, Li; metals of the alkaline earths, Ba, Ca, Sr, Mg; metals proper, as Fe, Pb, Sn.]. D. Metalloids: as C, P, Si, S. Witthaus's classification is excellent in many respects: Class I, typical elements: H and O. Class II, elements whose oxides plus water form acids, viz: Fl, Cl, Br, I, S, N, P, As, etc. Class III: ele- ments whose oxides plus water in some form bases, in others acids: Au, Cr, Mn, Fe, Al, Pb, Bi, etc. Class IV, elements whose oxides plus water form bases only: Li, Na, K, Cu, Mg, Zn, etc. 92 DENTAL CHEMISTRY. CHAPTER III. INORGANIC CHEMISTRY. THE ELEMENTS AND THEIR INORGANIC COMPOUNDS. Monads. The elements will be taken up in the order of their valence, monads first. Of monads those positive* to hydrogen will be treated first, then those negative to it. TABLE 12. MONADS. Potassium 1 Silver Hydrogen Iodine ") Bromine Monads negative Chlorine to hydrogen. Fluorine. Hydrogen forms hydrides with those elements positive to itself, as KH, potassium hydride. Combined with those negative to it iodides, bromides, chlorides, and *See Table 1. The student will do well to study the properties of hydrogen (section 176) and of oxygen (section 241) before beginning this chapter. INORGANIC CHEMISTRY 93 fluorides are formed. Moreover, all in the list above hy- drogen are positive to all in the list below hydrogen. The elements positive to hydrogen in this list are all metals, those negative, non-metals. Potassium: Symbol: K. Latin name: Kalium. Equiv- alence: I. Specific gravity : 0.86. Atomic z^2^/(approx.): 39. Revised atomic weight: 39.0196. Electrical state : +. Fusing point: I44 F. Brilliant, white metal, with high degree of lustre, soft, floats on water and takes fire spontaneously when thrown on it, yielding an alkaline solution. 162. Potassium compounds. TABLE 13 SOME COMPOUNDS OF POTASSIUM. Name. Formulae. Uses, etc. White, soluble in water (6 in 100). Used in r\^\^ vr\c\ mouth washes and gar- Chlorate KC1O, g]qs In large doses is poisonous. Sparingly soluble in alcohol. Antacid, used in mouth washes. In large doses Bicarbonate KHCO 3 is corrosive poison. Soluble in water, insol- uble in alcohol. White, soluble crystals. Given internally in con- Bromide KBr vulsions, etc., and used locally to diminish sen- sibility before taking 1 impressions. 94 DENTAL CHEMISTRY TABLE 13. Continued Transparent, colorless solid, soluble in water. Chloride KC1 Found in the body in fluids, blood corpuscles, and in muscle juice. Made by dissolving iodine in potassium hy- drate. Large, white Iodide KI translucent, cubical cry- stals of a saline taste. Readily soluble in water. Solutions dissolve iodine. 163. Potassium hydrate. - Synonyms: Potassa U. S. P., Potassa Caus- tica (Br. P.), caustic potash. Theoretical constitution: KHO or KOH, the hydrate (hydroxide) of potassium. Molecular weight, 56. Preparation: by boiling potassium carbon- ate with slacked lime (calcium hydrate): K 2 CO 3 + Ca(HO) 2 = CaCO 3 + 2KHO. Properties: the impure contains lime and is called potash by lime: purified by dissolving in alcohol and evaporating to dryness, re- melted, and cast in sticks it is known as fiotash by alcohol. White, opaque sticks or lumps, alkaline, readily soluble in water, caustic, escharotic, and corrosive poison. Potassa citm calce: equal parts KHO and CaO, grayish-white powder, milder, and less INORGANIC CHEMISTRY. 96 deliquescent; in a paste called Vienna paste, used in dentistry. Robinson s remedy contains potassium hy- drate and carbolic acid, equal parts. Liquor potasscz is a 5 per cent solution of potassium hydrate in water. Toxicology: potassium hydrate is a corrosive poison and its action on tissues is very violent and penetrating. Forty grains have caused death. In the treatment the stomach pump must not be used, dilute vinegar should at once be given, lemon juice, orange juice, olive oil, and milk freely. Stimulants are indicated if there is much pain. Solutions of potassium hydrate or carbonate have a soapy "feel" and are alkaline in reaction. Burns from the agent should be treated with dilute vinegar and then with oil. 164. Potassium Nitrate. Synonyms: nitre, saltpetre, Sal Prunella. Official name, Potassii Nitras. Theoretical constitution: KNO 3 , i atom of potassium, i of nitrogen, and 3 of oxygen to the molecule. Molecular weight, 101. Preparation: made from crude sodium nitrate by double decomposition with potas- sium chloride. Properties: colorless crystals, anhydrous, very soluble in hot water, readily soluble in cold, nearly insoluble in alcohol, permanent in dry air, neutral, odorless. Uses in dentistry: locally and in mouth washes as an antiseptic and refrigerant. In refining gold, when it is used as an oxidizing 96 DENTAL CHEMISTRY. agent for metals alloyed with gold. Roasting an alloy with nitre will often set the gold free. Toxicology: potassium nitrate is poisonous, causing severe burning, abdominal pains, nausea, vomiting of blood, great prostration, tremors, collapse. One ounce has proved fatal. The treatment is to give an emetic, mucilaginous and demulcent drinks, and stimulants. 165. Potassium Permanganate. Synonyms: permanganate of potash. Official name, Potassii Permanganas. Theoretical constitution: K 2 Mn 2 O 8 or KMnO 4 , derived from permanganic acid. Permanganic acid, H 2 Mn 2 O 8 , may be deemed to be derived from manganese heptoxide (Mn 2 O 7 ) plus water (H 2 O); potassium permanganate K 2 Mn 2 O 8 , by exchanging the two atoms of hydrogen in the acid for two of potassium. Molecular weight, 313.8. Properties and dental uses: potassium per- manganate occurs in the form of dark purple crystals which impart a fine, deep, purple color to water even when in very minute propor- tions. It is a deodorizer, disinfectant, and, in concentrated solution, a caustic. Condys Fluid contains 32 grains of it to the pint of distilled water. Liquor Potassii Permanganatis contains 64 grains to the pint of distilled water. In dental practice the permanganate is used locally as a deodorizer, disinfectant, and an- tiseptic. 1 66. Sodium: Symbol'. Na. Latin name'. Natrium or Natron. Equivalence'. I. Specific Gravity: 0.97. Atomic weight (approx.): 23. Revised atomic weight: 22.998. Electrical INORGANIC CHEMISTRY. 97 state: X. Fusing point: 2o6.6 F. Properties: Soft, white, readily oxidized metal. 167. Sodium Compounds. Sodium Hydro-Carbonate or Bicarbonate. Synonyms: bicarbonate of sodium, bicar- bonate of soda, sodium acid carbonate, sesqui- carbonate of sodium, "baking soda." Theoretical constitution: sodium hydrocar- bonate, NaHCO 3 , is what is called an acid salt, because all the hydrogen atoms of the acid from which it is derived have not been replaced by the positive atom. The term acid salt should not confuse the beginner as to the reaction of the substance to litmus paper, which has nothing to do with the theoretical name. Sodium bicarbonate is composed of one atom of sodium, one of hydrogen, one of car- bon, and three of oxygen. By weight 23 of sodium, i of hydrogen, 12 of carbon, 48 of oxy- gen; molecular weight, 84. Preparation: made by passing carbon diox- ide over sodium carbonate from which the larger portion of water of crystallization has been expelled: Na 2 CO 3 + H 2 O + CO 2 = 2NaHCO 3 . Sodium water carbon sodium carbonate dioxide bicarbonate. The sodium carbonate used is, as will thus readily be seen, an entirely different substance from the bicarbonate. The former is known 98 DENTAL CHEMISTRY. in commerce as " sal soda," and familiarly known as "washing; soda." Properties: sodium bicarbonate is a white powder, having 1 a mildly saline, cooling taste, a slightly alkaline reaction, is soluble in 12 parts of water, insoluble in alcohol; 8 parts of the bicarbonate are soluble in 100 of glycerine (by weight). Its solutions are nearly neutral to litmus paper. Use in dentistry: sodium bicarbonate is in particular used as an antacid ingredient of dentifrices, and its uses, in general, in dental practice are in consequence of its antacid prop- erties. 168. Various sodium compounds: all are soluble in water to a greater or less degree and most of them in solution turn red litmus blue. Many of them are white or colorless. TABLE 14 SODIUM COMPOUNDS. Name. Chloride Sulphite Sulphate Carbonate Arseniate Hydrate Phosphates Formulae. NaCl Na 2 SO 3 Na 2 SO 4 Na 2 CO3,10H 2 O Na 2 HAsO 4 , 7H 2 O KHO NasPOi Na 2 HPO 4 NaH 2 PO 4 Origin, Uses, etc. Common salt is found in every fluid and organ of the body. ( Antiseptic, disinfectant, and de- j odorizer. Used in bleaching ( teeth with boracic acid. Glauber's salt. Washing Soda. Poisonous, colorless, efflorescent. ( Caustic soda. Comes in form of ( sticks. Readily soluble. ( Basic phosphate, alkaline, and \ purgative. Neutral phosphate. Found in the tissues. Acid phosphate of sodium. INORGANIC CHEMISTRY. 99 169. Sodium Borate or Borax. Synonyms: sodium biborate, sodium tetra- borate, Sodii Boras (U.S.P), Sodae Boras (B.P.). Theoretical constitution: formula Na 2 B 4 O 7 , explained by regarding- it as Na a O.(B 2 O 3 ) 2 or Na 2 O.2B 2 O 3 . Boric oxide (anhydride) B 2 O 3 , has the property of uniting directly with oxides of the positive elements sodium, potassium, etc. Borax is not, therefore, derived from boracic acid but formed by the direct combin- ation of sodium oxide, Na 2 O, with boric ox- ide or anhydride, B 2 O 3 . The molecule of sodium oxide' combines with two molecules of boric oxide, forming Na 2 O.2B 2 O 3 . Borax con- tains also ten molecules of water of crystalliza- tion, so that the full formula is Na 2 O.2B 2 O 3 + ioH 2 O. Properties and uses in dentistry: borax is a white, soluble, efflorescent substance which melts at a low heat, swells greatly, at a higher temperature becomes a clear liquid, then a vitreous substance (borax glass). It is useful in blow pipe analysis, as by the <( borax bead" method; as a flux for melting metals; in sold- ering metals; in solution, for hardening plaster casts; as a local application, etc., etc- 170, Sodium Hypochlorite. Theoretical constitution: NaCIO, one atom of sodium, one of chlorine and one of oxygen in its molecule. This 100 DENTAL CHEMISTRY. substance is only indirectly of interest as one of the in- gredients of the chlorinated soda solution. Liquor Sodcz Chloratce: Synonyms: Labarraque's solution, solution of chloride of soda; chlorinated soda solution. Preparation: made by decomposing a solution of chlor- inated lime with one of sodium carbonate: [Ca(ClO) 2 + CaCl 2 ] + 2NaCO 3 = [2NaClO + 2NaCl] + 2CaCO 3 Chlorinated lime. Chlorinated soda. Calcium carbonate. Properties: clear, pale liquid, slightly greenish yellow in color, of faint chlorine odor, alkaline taste and reaction. Sp. gr., 1.044. Powerful disinfectant, deodorizer, antisep- tic, bleaching agent. Use in dentistry: used locally for its antiseptic proper- ties and, in combination with powdered alum, as a bleach- ing agent for discolored teeth. It slowly decomposes on exposure to air and light, and should be kept in a dark place in a bottle provided with a glass stopper. It is advisable to keep soda and potash solutions in bottles whose glass stoppers have been dipped in paraffine. Eau de Javelle contains potassium hypochlorite. 171. Ammonium and its Compounds. Ammonium (NH 4 ) is what is known as a radical. (See Organic Chemistry). It is not positively known to exist nor is its oxide. There are reasonable grounds, however, for supposing that it does actually exist in cer- tain compounds called the ammonium com- pounds, all of which contain NH 4 in their for- mulae. Ammonium is not ammom#/ the latter is a well-known gas, NH 3 , while ammonium has never been isolated and has, therefore, only a hypothetical existence. Ammonium would INORGANIC CHEMISTRY. 101 seem in the main to resemble sodium and potassium; there are, however, points of dis- similarity. TABLE 15. COMPOUNDS OF AMMONIUM. Names. Formulae. Properties. H 4 NHO or NHiHO Volatile, caustic liquid of power- Hydrate, Sometimes written ful odor. Aqua Ammoniae is a solution of ammonia gas in (Ammonia water). AmHO. May be deemed a hydrate water, of sp. gr. 0.959. Aqua Ammonias Fortior contains 28 of the radical am- per cent, of the gas and is of Carbonate, monium. sp. gr. 0.900; it is a powerfully Amrnonn (NHiHCOs, NH4NH2CO2) corrosive poison. carbonas. Hartshorn salt Really a mixture of the acid carbonate and the carbamate. Has strong odor of ammonia and is freely soluble in water. Loses COa and NHa on expos- Sal Volatile. Molecular wt., 157. ure to the air. Chloride, White, crystalline powder; very or Tnuri3.tG. NHiCl= 63.4 easily soluble in water, but not O 1 hygroscopic. Used as flux in oal ammoniac. refining gold, etc., and locally. Lithium : Symbol: Li. Latin name: Lithium. Equivalence: I. Specific gravity: 0.59. Atomic ivt. (approx.) : 7. Atomic wt. (revised): 7.0073. Electrical State: +. Fusing point: 356 F. Properties: White, oxidizable metal and the lightest metal known. 172. Silver. Symbol: Ag. Latin name: Argentum. Equivalence: I and III. Specific gravity: 10.40 to 10.57. Atomic weight 108. Revised atomic weight: 107.675. Electrical state : + Fusing point: i873F. Expands on solidifying. Length of 'bar at 212: 1.0021; (6th rank). Wt. of cubic ft. inlbs.: 657.3. Tensile strength : 18.2; (lead = I ). Tenacity: 12.5*; (5th rank). Malleability: 2; (2d rank). Ductility: 2; (2d rank). Conducting power, heat: i; (ist rank). Conducting power, electricity: i; (ist rank). Resistance ""Compared with lead. 102 DENTAL CHEMISTRY to air, etc,; tarnished by sulphuretted hydrogen, but not affected by air. Solubility: in nitric acid, hot strong sul- phuric, hydrochloric with difficulty; not attacked by caustic alkalies nor by melted nitre. It is dissolved by mercury. Direct combinations: with halogens, chlorine, bromine, etc., and with sulphur and phosphorus. Color white, brilliant. Structure : isometric crystals, when cooled slowly from fusion. Consistence: soft. Intermediate in hardness between gold and copper. Compounds : argentic, as argentic nitrate, etc. Ordinary alloys: silver coins, gold solders, silver solders, silver vessels, silver jewelry, Occurrence: silver is found in combination with some of the halogens as chlorine, bro- mine, iodine, with various other non-metals as sulphur, arsenic, antimony, and with copper. It occurs in the Western states, in Mexico, Saxony, Hungary, Norway, South America and elsewhere. It is sometimes found native*. Preparation: the methods are various and elaborate. The Washoe process is to grind the ores with water, in iron pans heated by steam. Mercury is added, the sulphide of silver is decomposed by the iron, sulphide of iron formed and metallic silver set free, dissolved in mercury and the mercury separated by pressure and distillation. *Native silver is that found not as a sulphide, etc., but uncombined. Native silver is found in crystals, threads, or amorphous masses, weighing often several pounds. It is associated, nearly always, with other metals in small quantities, and accompanied by its sulphide or chloride. INORGANIC CHEMISTRY. 103 Pure silver may be prepared by reducing" the chloride, by fusing it with dry sodium car- bonate. Other methods are also used: one is to dissolve standard or other -grades of silver in slightly diluted nitric acid, precipitate the solution by excess of common salt, place the well-washed chloride in water acidulated with hydrochloric acid, and add a few pieces of clean wrought iron: hydrogen is evolved which, uniting with the chlorine of silver chlor- ide, leaves the silver as a spongy mass. After the removal of the iron and decantation of the liquid, the silver is well washed in hot water containing a little hydrochloric acid, dried and melted. Uses in dentistry: silver is used in amalgam alloys and, according to Flagg, is the first, most important, and essential metal of a good amalgam alloy for filling teeth; it is the largest component of every truly good "sub- marine," "usual," or "contour" alloy in the market. Its presence in an amalgam is es- sential to proper setting; it notably maintains the bulk integrity of the filling; though dis- colored by sulphuretted hydrogen, the silver sulphide formed is highly conducive to the permanent saving of teeth largely decayed and predisposed to continued decay. Silver has also been used in dental plates. 104 DENTAL CHEMISTRY. 173. Silrer alloys and alloys resembling silver . Silver coinage: silver 90, copper 10. Silver vessels: silver 95, copper 5. Silver jewelry: silver 80, copper 20. An alloy used in England for temporary dentures is silver 24 parts, platinum 3 to 10 parts. German silver contains no silver, but is an alloy of cop- per, nickel, a*nd zinc, in the proportions of 40.4 copper, 31.6 nickel, 25.4 zinc, and sometimes 2.6 iron. 174. Silver solder is 32.3 parts copper, 38.5 silver, 29.2 zinc. Others are as follows: (Richardson). No. l. Silver, 66 parts. Copper, 30 parts. Zinc, 10 parts. No. 2. Silver, 6 dwts. Copper, 2 dwts. Brass, 1 dwt. No. 3. Silver, 5}4 dwts. Brass wire, 40 grains. When the plate to be united consists of pure silver alloyed with platinum, the solder may be formed of the standard metal (coin), with 10 J h to 6 th its weight of zinc, according to the amount of platinum in the alloy. 175. Compounds of silver. Silver titrate or Argentic Nitrate. Synonyms: lunar caustic, lapis infernalis. Official name, Argenti Nitras. Theoretical constitution: AgNO 3 , one atom of silver, one of nitrogen, three of oxygen; by weight, silver 107.7 parts, nitrogen 14, oxygen 48. Molecular weight, 169.7. Properties and uses: on evaporating a solu- tion of silver in nitric acid and water, nitrate of silver is obtained in the form of colorless, heavy, shining, rhombic plates. It is black- ened by exposure to light, and by contact with organic matter. It is also prepared in stick form, by fusing and pouring into moulds. It INORGANIC CHEMISTRY. 105 is very soluble in water, and slightly iu alcohol. It is used in dentistry as an astringent, styptic, and obtunding agent. It blackens tissues with which it comes in contact, and is a powerful escharotic. Should be kept in amber bottle with glass stopper. Toxicology: silver nitrate is an irritant, corrosive poison. The antidote is common salt or sal-ammoniac. Emetics should be given, and white of egg adminis- tered freely. Silver Sulphide. Silver has a strong affinity for sul- phur, the sulphide, Ag 2 S, being formed in the mouth by action of sulphuretted hydrogen on an alloy containing silver. Silver can, therefore, not be used in connection with substances containing sulphur, as rubbers. Silver sulphide is soluble in nitric acid, is soft and malleable. Silver Chloride, AgCl, is formed when either common salt or hydrochloric acid is added to a solution of silver nitrate. Silver Oxide, Ag 2 O, is obtained as a brown precipitate, when solution of silver nitrate is decomposed by potash. Take of silver nitrate TOO Gm., of distilled water 2OO C.c., of solution of potassa (official) 600 C.c. Dissolve the sil- ver nitrate in water and add solution of potassa as long as any precipitate is produced by it. Wash the precipitate with distilled water, until washings are nearly tasteless. Dry the product and keep it well protected from the light. It parts with its oxygen easily and must not be heated nor brought into contact with ammonia. Should be kept in a well-closed bottle and in a cool place. It is used as a coloring matter for artificial teeth. 176. Hydrogen. Symbol: H. Atoms in molecule: H 2 . Atomic weight'. I. 106 DENTAL CHEMISTRY. Molecular weight: 2. Density, i. Specific gravity: 0.0692. Weight of one litre of hydrogen gas: 0.0896 gramme. How liquified: by pressure of 650 atmospheres at 140 C. Occurrence in Nature. In volcanic gases and sun's atmosphere. How made. By decomposing an acid with a metal: thus, sulphuric acid with zinc: H 2 SO 4 + Zn = ZnSO, + H* Properties. Has affinity for chlorine only; at higher temperatures for oxygen. Is a gas, colorless, tasteless, odorless, transparent, and but slightly soluble in water. Is the lightest known substance and burns with the hot- test flame. Use in dentistry. Used in connection with oxygen in the oxyhydrogen blow pipe for fusing refractory substances. (See Oxygen). In combination with carbon alone forms hydrocarbons, among which are the volatile oils, as oil of cloves. (See Organic Chemistry). 177. Compounds of hydrogen: hydrogen monoxide or water. Synonyms: Aqua; distilled water, Aqiia Destillata. Theoretical constitution: H 2 O, hydrogen monoxide, composed of two atoms of hydrogen and one of oxygen, by weight 8 parts of oxygen to i of hydrogen. Molecular weight, 18. Specific gravity, i. Origin: occurs in nature in lakes, rivers, etc., and in three states the solid as ice, the liquid, and the gaseous as steam or vapor. In the air it is in form of vapor. Seven-eighths of the human body is water. Is always formed when hydrogen or any substance containing hydro- gen burns in the air. INORGANIC CHEMISTRY. 107 The freezing; point of water is 32 on the Fahrenheit scale of thermometers, but zero on the Centigrade; the boiling; point is 212 on the Fahrenheit, but zero on the Centigrade. Heater is expanded by heat and contracts on cooling, but after reaching 39 F. begins to expand again so that the volume of a given weight of water is less than the volume of ice formed from it. Ice contracts, then, on melting. On the other hand when water is converted into steam there is great expansion, one volume of water yielding 1700 volumes of steam. The capacity of water for heat is greater than that of all bodies except hydrogen. Adopting for the unit of measure that quantity of heat which will raise the temperature of one gram of water through one Centigrade degree those fractions of the unit of heat which will raise various substances, other than hydrogen, as iron, lead, or glass one degree are called the specific heats of the substances. (See Table i). The specific heat of hydrogen is 3.4, that of iron 0.1138, that of lead 0.0314. (See Sec- tion 59.) Water has a very general solvent powervfa\$\, however, is limited and varies with temperature, some substances being much more soluble in hot water than in cold water. Among sub- stances very soluble in water we find potassium carbonate and zinc chloride. (See Section 68). 108 DENTAL CHEMISTRY. Well waters on being- evaporated yield a residue composed usually of compounds of calcium, magnesium, etc., which have previ- ously been held in solution. Heater enters into the formation of crystals, readily shown by preparing a saturated solu- tion of such salts as alum, potassium ferro- cyanide, potassium nitrate, magnesium sul- phate, and letting stand in a shallow dish until evaporation has taken place. Heater is the medium of chemical change. (See Section 141.) Water combines with certain substances, forming hydrates with oxides of positive elements, and anhydrides with oxides of nega- tive elements. Examples: quicklime and water form slaked lime; that is, calcium oxide and water form calcium hydrate; sulphurous oxide and water form sulphurous anhydride. In general water is a limpid, colorless liquid, odorless, tasteless, neutral, poor conductor of heat and electricity, 773 times heavier than air, standard of specific gravity. The purest natural water is rain water. This, however, is somewhat contaminated with matters washed from the air. River and lake waters, espec- ially those found in granitic regions, are the purest potable waters. Mineral waters are called alkaline, sulphurous, chalybeate, etc., according to prevailing constituents, and con- INORGANIC CHEMISTRY. . 109 tain usually large amounts of solids in solu- tion. Use in dentistry: distilled water is used in the preparation of many dental formulae. It is prepared by taking- 80 pints of water, distill- ing two pints which are rejected, then distilling 64 pints. The term aqua, U. S. P., is used as a name for a solution of some gaseous or vola- tile body in water. Thus, aqua chlori; the term liquor is used when the substance dissolved is fixed or solid, as Liquor PlumM Subacetatis. 178. Hydrogen Dioxide. Synonyms: hydrogen peroxide, hydric diox- ide or peroxide, oxygenated water. Theoretical constitution: H 2 O 2 , hydrogen dioxide, composed of two atoms of hydrogen and two of oxygen; by weight, 32 of oxygen to 2 of hydrogen, or 16 to i . Molecular weight, 34. Preparation: pass a stream of carbon dioxide through water containing barium dioxide in suspension: BaO 2 + CO 2 + H 2 O - BaCO 3 + H 2 O 2 . Barium dioxide carbonic dioxide water barium carbonate hydric dioxide. Properties: in the purest form it is a syrupy colorless liquid, having an odor like chlorine or ozone, and a tingling, metallic taste. It is never used in the purest undiluted form in den- tal operations owing to the readiness with which it decomposes and gives off its oxygen. It is a powerful antiseptic, colorless, odorless, cleans- 110 DENTAL CHEMISTRY. ing" and stimulating;, does not stain or corrode, and is not poisonous. It gives off its oxygen with effervescence in contact with many sub- stances and notably with pus. Application to dentistry: is efferveses with pus, giving off nas- cent oxygen, which is a powerful bactericide; being one of the most cleansing of agents, it is used to clean cavities. Combined with weak alkali it bleaches. A "ten volume" solution of it is one which will give off ten parts by vol- ume of oxygen; that is, one measure of it gives off ten measures of oxygen. A "two volume" solution contains 0.4 per cent, of the pure dioxide. A little acid is added to the solutions of the dioxide commonly used in dentistry as an aid to their stability .f Hydrogen dioxide should be kept in a cool place in a glass-stop- pered bottle. Hydrogen dioxide is sometimes used in solution in glycerine instead of in water. It gives off its oxygen more slowly than when in aqueous solution. 179. Iodine. Symbol: I. Atoms in molecule: I 2 . Atomic weight: 127. Molecular weight: 254. Density: 127. Spe- cific gravity : 4.95. Weight of one litre of gas : 11.37 gram- mes. How liquefied: at 225 F. Solubility in water: 7000 parts of water dissolve I of iodine. Freely soluble in alcohol and in aqueous solution of potassium iodide. Occurrence in nature: in combination, as iodides, etc, How made: from ashes of sea-weed. By action of chlorine fRollins has found that as ordinarily obtained it acts perceptibly on the teeth, and hence should be used with caution. INORGANIC CHEMISTRY 111 and heat on liquor obtained by leaching sea-weed ashes. Properties: solid, in brilliant scales, of gray metallic color. Gives off violet vapors. Imparts yellowish-brown stain to skin. Solutions when cold give blue color to boiled starch. Not so corrosive or poisonous as bromine, but yet poisonous in sufficient quantity. Antidote, starch. Preparations used in dental pharmacy. Tincture of iodine, Tinctura lodi, is made of 80 grams of iodine in 920 grams of alcohol. Compound solution of iodine, Liquor lodi Compositus is iodine 50 grams, potassium iodide 100 grams, distilled water 850 C. c. De- colorized tincture of iodine, Tinctura lodi De- colorata, is iodine 40 grams, alcohol 400 C. c., stronger water of ammonia 90 C. c. Car- bolized iodine solution, Liquor lodi Phenola- tus, is tincture of iodine i gram, phenol (car- bolic acid) 12 centigrams, glycerine 8 grams, water 45 C. c.; it is a colorless liquid. The antidote for iodine is starch. Bromine. Symbol: Br. Atoms in molecule: Br 2 . Atomic weight: 80. Molecidar weight 7160. Density: 80. Specific gravity: 3.187. Weight of one litre of gas: 7.15 grammes. How liquefied: at ordinary temperatures. Sol- ubility in water: 33 parts water dissolve one of bromine. Occurrence in nature: in combinations as bromides, etc. How made : action of sulphuric acid on bittern in presence of manganese dioxide. Properties: liquid, heavy, dark, brownish-red, less active than chlorine, bleaches, burns, is poisonous, colors starch yellow. Fumes violently. Is heavier than some metals, as aluminium. 1 80. Chlorine. Symbol: Cl. Atoms in molecide: C1 8 . 112 DENTAL CHEMISTRY. Atomic weight : 35.4. Molecular weight: 71. Density: 35.4. Specific gravity : 2.47. Weight of one litre of gas: 3. 17 gram- mes. How liquefied: 4 atmospheres or 40 F. Solubility in water: I part, by volume, of water dissolves nearly three volumes of chlorine gas. Occurrence in nature: always in combination, usual source common salt. How made: (a) action of H 2 SO 4 on NaCl in presence of Mn O 2 ; (b} action of air on moistened "chloride of lime." Properties: is a gas, greenish-yellow, of pungent taste and suffocating odor, wholly irrespirable, powerful bleaching agent and disinfectant. Combines with all elements ex- cept oxygen, nitrogen, and carbon. Use in dentistry. Chlorine gas has been used to bleach discolored teeth. It may be prepared as follows: Place 20 parts, by weight, of commercial hy- drochloric acid (sp, gr. about 1.16) in a flask, add 8 parts manganese dioxide, agitate, and after a time heat the flask on a sand bath (safety-tube may be used, which is a funnel- tube bent twice on itself). The equation is as follows: 4HC1 + MnO 2 == MnCl 2 + 2H 2 O + C1 2 . The flask should be closed by a cork perfor- ated by two holes, through one of which the safety-tube may be inserted, its lower end dip- ping below the surface of the acid; through the other hole a short glass tube bent at right angles should be inserted, its lower aperture being about an inch below the cork. The gas escapes through this second tube, called deliv- INORGANIC CHEMISTRY. 113 ery tube, and may be collected in any way desired. Chlorine water is used in dental practice as a local application. It is prepared by passing the gas into water in which it is readily solu- ble, one volume of water dissolving three vol- umes of chlorine gas. The solution Aqua Cklori, U. S. P., is a greenish-yellow liquid, slowly changing in the light to hydrochloric acid. It should not redden litmus but bleach it. It should be kept in a glass-stoppered bottle away from the light and in a cool place. It should contain 0.4 per cent of chlorine. Toxicology. Chlorine gas is an irritant poison, and is irrespirable, causing inflammation of the air passages. The treatment is instant removal to fresh air, inhalation of ammonia or very dilute sulphuretted hydrogen or ether- vapor. The inhalation of steam is said to be beneficial. 1 8 1 . Compounds of chlorine. Hydrogen Chloride or Hydrochloric Acid. Synonyms: muriatic acid, chlorhydric acid, Acidum Hydrochloricum. Theoretical constitution: HC1, a hydracid, binary compound composed of one atom of hydrogen and one of chlorine; by weight 35.4 parts chlorine to i of hydrogen. Molecualr weight 36.4. Density of the gas, 18.25; sp. gr. 1.264. Absolute HC1 contains 97.26 per cent, of chlorine and 2.74 per cent, of hydrogen. Preparation: found free in small quantities 114 DENTAL CHEMISTRY. in gastric juice. Made from common salt and sulphuric acid: H 2 SO 4 + 2NaCl = 2HC1 + Na 2 SO 4 Sulphuric acid sodium chloride hydrochloric acid sodium sulphate. Properties: colorless, transparent gas of pungent odor, strongly acid reaction, very sol- uble in water, one volume of which dissolves 450 volumes of the gas forming the ordinary muriatic acid. Commercial muriatic acid is yellow, and the strongest contains 25 to 30 per cent, of the gas. Aciduni Muriaticum or Aci- dum Hydrochloricum, U. S. P., is colorless, sp. gr. 1. 1 6, contains 31.9 per cent of the gas. Acidum Muriaticum Dilutum, U. S. P.: strong acid 6 parts, distilled water 13 parts; sp. gr., 1.049. Use in dentistry: it is used as a solvent for zinc, and sometimes as a local application. It dissolves iron and zinc readily and, when warm- ed, attacks tin. Toxicology. Hydrochloric acid is a corrosive poison, caustic and escharotic. It stains the skin at first white, then produces discoloration. The stain on black cloth is red, gradually disappearing in course of time. Burns by the acid should be treated first by washing the acid off well, then by application of sodium bicarbonate solution and oil. If the acid be taken internally, give at once magnesia or bicarbonate of sodium in milk at short inter- vals, then bland liquids as raw eggs, gruel, or oil. 182. Fluorine. Symbol: ForFl. Atoms in molecule: F1 2 . Atomic weight: 19. Revised weight: 18.9840. Molecular weight: 38. Density: 19. Weight of one litre of gas: 1.7 INORGANIC CHEMISTRY. 115 grammes. Occurrence in nature: in combination as in fluor-spar and cryolite which are fluorides. How made: cannot be readily isolated. Properties: colorless gas. 183. Dyads. The dyads of importance will be studied in the same relative order as the monads. TABLE 16. DYADS OF IMPORTANCE. Barium Calcium Magnesium Zinc Cadmium Lead Uranium Copper Mercury Dyads positive to hydrogen. 184. Barium. Symbol: Ba; Latin name; Barium. Equivalence ; \\, Specific gravity: 4. Atomic wt. (approx.}; 136.8. Atomic wt. (revised}: 136.763. Electrical state ; +. Fusing point; below red heat. Properties; malleable, decomposes water, gradually oxidizes. Compounds of barium. Barium chloride, BaCl 2 , and barium nitrate, Ba(NO 3 ) 2 , are both soluble in water and are used in laboratory work in testing for sulphuric acid and sulphates. 185. Calcium. Symbol; Ca; Latin name; Calcium. Equivalence; II. Specific gravity: 1.58. Atomic weight (approx.} : 40. Atomic weight (revised}: 39.99. Electrical state : -\-. Fusing point: burns when heated. Properties; light yellow metal, about as hard as gold, very ductile, tarnishes slowly, decomposes water. 116 DENTAL CHEMISTRY. 1 86. Calcium compounds. Calcium Sul- phate. Synonyms: sulphate of Calcium, sulphate of lime, plaster-of-Paris, calcic sulphate. Official name, Calcii Sulphas. Theoretical constitution: CaSO 4 .2H 2 O, one atom of calcium, one of sulphur and four of oxygen; by weight 40 parts calcium, 32 parts sulphur, 64 parts oxygen. Molecular weight, 172. Preparation: calcium sulphate occurs in na- ture as a mineral called gypsum. Gypsum, however, differs from the dried calcium sul- phate of commerce in that it contains two mol- ecules of water of crystallization; the full formula for gypsum is, therefore, CaSO 4 , 2H 2 O. Ground gypsum is called terra alba. Gypsum when heated to 392 F. loses its water of crystallization, becoming changed into a white, opaque mass having CaSO 4 , without any H 2 O, for its formula. This substance when ground is known as plaster-of-Paris and is an- hydrous calcium sulphate; it readily recom- bines with water, becoming a hard mass on the addition of H 2 O. Properties and uses: the anhydrous sulphate, CaSO 4 , plaster-of-Paris, is a hard, white, nearly insoluble substance. After taking up water it "sets" into a stone-like solid, and hence is use- ful in making moulds, casts, and immovable INORGANIC CHEMISTRY. 117 surgical dressings. If alum and gelatine be mixed with the plaster-of-Paris before addition of water, it forms a harder and less porous mass than the plaster alone, and presents a smooth surface which can be washed with water con- taining the various disinfecting agents. 187. Calcium Carbonate. Synonyms: calcic carbonate, Calcis Car- bonas, carbonate of lime. Official name, Cal- cii Carbonas Prascipitatus. Theoretical constitution: CaCO 3 , one atom of calcium, one of carbon, three of oxygen; by weight 40 parts calcium, 12 carbon, 48 oxygen. Molecular weight, 100. Origin and method of preparation: it occurs more or less pure in nature as chalk, limestone, marble, Iceland spar, coral, shell, etc. It is found in the bones, teeth, saliva, and in cal- culi and tartar. It is obtained for dental uses ( i ) by precipi- tation, by mixing solutions of calcium chloride and sodium carbonate: Na 2 CO 3 + CaCl 2 = CaCO 3 + 2NaCl 23 2 = 3 dium _|_ Calcium Calcium _ carbonate chloride carbonate chloride (2) as prepared chalk (Creta Praeparata) by grinding a native chalk in water, allowing the mixture to settle, decanting the upper portion, collecting and drying the finer particles. Properties and uses: precipitated calcium carbonate is a neutral, white, tasteless, impal- 118 DENTAL CHEMISTRY. pable powder; it is insoluble in pure water and in alcohol, but soluble in water containing; car- bonic dioxide (carbonic acid). It is found as acid carbonate, dissolved in almost all natural waters, causing 1 hardness, which may be re- moved by boiling-, hence called "temporary" hardness. It is used in dentistry as a polishing powder, as an ingredient of dentifrices, and as an ant- acid. It is useful- as an antidote in cas.es of poisoning- by acids. 1 88. Calcium Oxide. Synonyms: calcic oxide, lime, Calx, quicklime, burned lime. Official name, Calcii Oxidum. Theoretical constitution; CaO, calcium oxide, one atom of calcium and one of oxygen in its molecule; by weight, 40 parts of calcium to 16 of oxygen. Molecular weight, 56. Preparation; lime is obtained on a large scale by heat- ing limestone or other calcium carbonate in a lime kiln: CaCO 3 = CaO + CO 2 Calcium Calcium _i_ Carbon carbonate = oxide dioxide. For pharmaceutical purposes it is made by heating mar- ble in a Hessian crucible. Properties and uses: lime is a grayish-white amorph- ous solid, odorless, infusible, of alkaline taste and reaction. It becomes incandescent in the oxy-hydrogen flame, emitting a very intense white light. Made from marble it should be pure white. 189. Calcium Hydrate. Slaked lime, Calcii Hydras. Formula, Ca( HO ) 2 . Molecular weight, 74. Prepared by adding 10 parts water to 16 of lime, letting cool, and straining. Dry, white, odorless, tasteless, alkaline pow- INORGANIC CHEMISTRY 119 der. None but recently prepared calcium hydrate should be used, as it soon becomes carbonate, absorbing carbonic dioxide from the air. Mortar is a mixture of sand, water, and slaked lime; as the water evaporates mortar hardens, because part of the lime becomes a carbonate, absorbing carbon dioxide from the air, and part a silicate combining with the silicic acid of the sand. Cement or hydraulic mortar is a mixture of powdered quartz, lime, and aluminium silicate; its hardening is due to the formation of calcium and aluminium silicates. Lime Water or Liquor Calcis is a clear solu- tion of calcium hydrate in water. Sugar in- creases the solubility of the calcium hydrate. Lime water is a colorless, nearly odorless liquid, of feebly caustic taste and alkaline re- action. It is a solution of about 15 parts cal- cium hydrate in 10,000 of water. Milk of lime is lime water containing- an ex- cess of calcium hydrate, rendering" it turbid. Lime water is used in dentistry in form of g-arg;le as an antacid, astringent, etc. 190. Calcium Fluoride. Synonyms: fluor-spar, fluoride of lime, Calcii Fluor- idum. Theoretical constitution: CaFl 2 , one atom of calcium and two of fluorine, 40 parts by weight of calcium, and 38 of fluorine. Molecular weight, 78. Preparation: calcium fluoride occurs in nature as fluor- spar; it is made artificially by treating a salt of calcium with potassium fluoride. Properties: human bone contains about two per cent. of calcium fluoride; the enamel of teeth contains it also. 120 DENTAL CHEMISTRY. It is a very hard substance, insoluble in water, but de- composed by sulphuric acid, hydrofluoric acid being formed. 191. Calcium Sulphite. Sulphite of lime, Calcii Sul- phis. Formula CaSO 3 , 2H 2 O. Molecular weight, 156. Made by saturating milk of lime with sulphurous oxide, collecting, and drying the precipitate. It is a white pow- der, slightly soluble in water, soluble in sulphurous acid. It gradually becomes converted to sulphate. Used as an antiseptic. 192. Chlorinated Lime. Official name, Calx Chlorata. Contains probably Ca(ClO) 2 , calcium hypochlorite. It should yield 25 per cent, chlorine on addition of acid. It is pre- pared by the action of chlorine on calcium hydrate. It is a white or grayish-white, dry or but slightly damp powder or friable lumps, of feeble chlorine-like odor, and disagreeable, saline taste. It should be kept in well-closed vessels, in a cool, dry place. It is partially soluble in water and in alcohol. It is a disin- fectant and a bleaching agent. It is used in dentistry as a deodorizer, disinfectant, anti- septic, and bleaching agent. It is poisonous in large doses. 1 93. Calcium Phosphate. Ca 3 ( PO 4 ) 2 , basic phosphate, tricalcic phosphate, bone phos- phate: found in whole organism, constitutes two-thirds of the teeth, found in bones and in calculi; in the ash of albuminous substances; white, insoluble. Readily soluble in acid solu- tions. INORGANIC CHEMISTRY. 121 194. CaJcium Hypophosphite. Ca(H 2 PO 2 ) 2 = 170. Prepared by dissolving phosphorus in milk of lime by aid of heat. Is a white salt, permanent in air, soluble in water, insoluble in alcohol. 195. Magnesium. Symbol: Mg.; Latin name: Mag- nesium. Equivalence: II. Specific gravity: 1.70 to 1.74. Atomic wt. (approx.}: 24. Atomic wt. (revised}: 23.959. Electrical state: + . Fusing point: melts at red heat. Proper- ties: magnesium is a brilliant, silver-white metal, lighter than silver or aluminium, tarnishing in damp air, burn- ing easily and with a flame of dazzling brightness. It is soluble in dilute acids and unites directly with most of the negative elements. TABLE 17. COMPOUNDS OF MAGNESIUM. Name. Formula. Properties, Uses, etc. Chloride MgCl 2 White, soluble, very bitten Oxide MgO Known as magnesia or cal- cined magnesia. White, in- fusible, antacid, antidote to arsenic and caustic acids. Sulphate MgSO, "Epsom salts." White, sol- uble, very bitter. Phosphate Mg 3 (P0 4 ) 2 Found in body along with calcium phosphate. Ammonio-mag- nesium phos- phate MgNH 4 PO 4 Called triple phosphate. Very soluble in acids, in- soluble in alkalies. Hypochlorite Mg(C10) 2 Used forbleachingpurposes. 196. Magnesium Carbonate. Synonyms: carbonate of magnesia, mag- nesia alba, salis amari. Official name, Mag- nesii Carbonas. Formula, 4MgCO 3 .Mg(HO) 2 .H 2 O. 122 DENTAL CHEMISTRY. Two kinds are known to pharmacy, the " heavy " and the " light." Both are prepared by dissolving- 25 parts of magnesium sulphate and 20 of sodium carbonate, each separately, in water, but the " light " carbonate is the result of mixing the solutions when cold, the " heavy " by dissolving in hot water and mix- ing while hot. There are certain other differ- ences also in the methods of preparation, the light carbonate solution being much more dilute than the heavy. The light carbonate contains more carbonate and less hydrate, is about three times as bulky, and is partly crystalline. The heavy carbonate is wholly amorphous. Both form a light, white mass or powder, nearly insoluble in water, but readily soluble in dilute acids. 197. Zinc. Symbol'. Zn.; Latin name: Zincum. Equivalence: II. Specific gravity: 7.10107.20. Atomic weight: 65. Revised atomic weight: 64.904. Electrical state: -+-. Fusing point: 773 F. Length of bar, etc.: 1.0029; (2d in rank, cadmium = i). Wt. of cubic ft. in Ibs.: 445.7. Tensile strength: 3.3 to 8.3. Tenacity: 2; (8th rank). Malleability: 7; (7th rank). Brittle, until heated to between 248 and 302 F. Ductility: 8; (8th rank). Conducting power (heat) : 5; (5th rank). Conducting power {electricity}: 290 (silver = i coo); (4th rank). Resistance to air, etc.: tarnishes slowly; in moist air becomes coated with carbonate. Sol- ubility: soluble in dilute acids, and in solutions of alkaline hydrates; slowly corroded by water, milk, and wine. Direct combinations: oxygen, chlorine. With iron, INORGANIC CHEMISTRY. 123 when heated to fusion. Color and appearance: bluish- white. Structure: crystalline; form of crystals, rhombo- hedral. Consistence: brittle. Compounds: zinc as zinc sulphide, zinc chloride, etc. Alloys: brass, bronze, bell metal, German silver, Aich's metal, arguzoid, Dutch metal, electrum, Muntz's metal, solders, sterro-metal, tutenag. Occurrence: zinc is found usually either as sulphide, zmc-blende, ZnS. or as carbonate, calamine, ZnCO 3 . It is also found as silicate and as oxide. Blende is found in Great Britain, Saxony, Aix-la-Chapelle, and in North America. .Calamine occurs in Great Britain, Aix-la-Chapelle, Silesia, Spain, and in many other places. Red zinc ore or oxide is found chiefly in New Jersey. Preparation: zinc is converted into vapor with comparative facility; it boils and distills at bright red heat. Hence, in order to extract zinc from its ores, the latter are first calcined, that is ignited in the air so as to burn off any oxidizable material, and the zinc obtained in form of oxide. The latter is then mixed with carbon and distilled, carbonic acid gas and zinc vapor being formed; the zinc vapor is condensed in suitable receivers. Properties: under ordinary circumstances zinc is brittle, but when heated to about 300 F., it becomes malleable and ductile, and may be rolled into thin sheets. At about 400 R, it becomes brittle, melts at 775 and at 1842 124 DENTAL CHEMISTRY. boils, volatilizes, and burns, if air be not ex- cluded, with a fine greenish-white light, the oxide being formed. Galvanized iron is iron covered with a coat- ing of metallic zinc. Dental uses: according to Flagg, zinc, in pro- portion of from i to i% parts in 100, if added to the usual 40 silver 60 tin alloys, seems to control shrinkage, imparts a "buttery" plas- ticity to the amalgam, adds to the whiteness of the filling, and assists in maintaining its color. Zinc is used in making dies for swaging plates. It may be used, according to Essig, in making counter-dies.* 198. Alloys of Zinc. Zinc and tin alloy for casting dies for swaging plates is, according to Richardson, zinc 4, tin I. Zinc in Solders. Solders made of the common com- mercial zinc are brittle, and are rolled with difficulty. They cause also a strong, brassy taste in the mouth, and should therefore be dissolved out of the finished work by pickling in nitric acid, the surface afterwards being burn- ished. Pure zinc in solders gives a plate that rolls easily, *Dies for making artificial teeth. [Rollins in Boston Medical and Surgical Journal, 1884], Metal plates are not as firm as rubber because they do not repre- sent so perfect a reverse of the mouth. This is mostly due to the imperfect character and softness of the metal dies on which they are struck. A perfect die can be made by preparing the surface of the impression for electrotyping and then depositing copper on it which if the die is to be used for striking, can be backed with a harder metal to the right firmness and form. Such a die is perfect and harder than any now in use. INORGANIC CHEMISTRY. 125 makes a handsome solder and causes much less of the brassy taste, so little indeed that most people do not per- ceive it. (Chandler.) 199. Compounds of Zinc: Zinc Chloride. Synonyms: butter of zinc, muriate of zinc. Official name, Zinci Chloridum. Theoretical constitution: ZnCl 2 , one atom of zinc and two of chlorine in the molecule; by weight, 64.9 parts of zinc to 70.8 of chlorine. Molecular weight, 135.7. It contains 47.83 per cent of zinc. Preparation, properties, and uses: zinc chlo- ride is made by heating zinc in a current of chlorine, or by the action of hydrochloric acid on granulated zinc or zinc carbonate, and evaporation of the solution to dryness. It occurs in the form of hard, dirty-white masses, very deliquescent, and forming a clear solution with ' water.* Zinc chloride has a caustic, sharp taste, and is acid in reaction. It is soluble in alcohol and in ether. " Burnett's Disinfecting Fluid " contains zinc chloride, in proportion of from 205 to 230 grains to the ounce of water. The official solution of chlo- ride of zinc, Liquor Zinci Chloridi, is an aque- ous solution of zinc chloride containing 50 per cent, of the latter, or 23.92 per cent, of zinc. It is made from 20 parts of granulated zinc, I part of nitric acid, I part of precipitated carbonate of zinc, and *It is one of the most soluble substances known. 126 DENTAL CHEMISTRY. sufficient hydrochloric acid and distilled water. To the zinc, enough hydrochloric acid is added to dissolve it; the solution is filtered, nitric acid added, the whole evaporated to dryness, and the dry mass brought to fusion. After cooling, it is dissolved in 15 parts distilled water, the precipitated carbonate of zinc added, and the mixture agitated occasionally during the 24 hours. Fin- ally it is filtered through washed asbestos free from iron, and enough distilled water added to it, through the filter, to make the product weigh 80 parts. The reaction is as follows: Zn + 2HC1 = ZnCl 2 + H s . Zinc hydrochloric zinc hydrogen acid chloride The solution is evaporated to dryness, and the dry mass fused in order to remove any excess of nitric acid. Zinc chloride solution cannot be filtered through paper; pow- dered washed glass or purified asbestos must be used. The solution is a heavy, strongly caustic liquid, which should mix with alcohol without precipitation. Its sp. gr. is 1.555.1 If of a sp. gr. of 1.1275 at 68 F., it contains only 13.876 per cent of zinc chloride; if its sp. gr. is 1.2466 it con- tains 25.819 per cent; if 1.3869, 37.483 per cent. Use in dentistry: zinc chloride is used in den- tal medicine for various purposes as an anti- septic, disinfectant, and deodorizer. A solution of it is used in connection with the oxide, to make a plastic filling (see zinc oxychloride). Toxicology: chloride of zinc rapidly coagulates albu- min. It is a caustic and irritant. Externally applied, it penetrates deeply into tissues and spreads, producing a white, thick, and hard eschar. In cases of poisoning from fA solution of this strength is used in making the oxychloride cement. INORGANIC CHEMISTRY. 127 internal administration, carbonate of sodium in milk, white of egg, or soap are the antidotes. 200. Zinc Oxide. Official name, Zinci Oxidum. ZnO = 80.9. Made on a large scale by heating" metallic zinc in a current of air. To make a pure white zinc oxide for pharmaceutical purposes, pure precipitated zinc carbonate should be heated at low red heat until the water and carbonic oxide are wholly expelled. This can be done below 500 F. The reaction is as follows: 2(ZnCO 8 ).3Zn(HO) a - S^nO + 2CO 2 + sH 2 O Zinc carbonate zinc oxide carbonic acid water Too high heat will give the product a yellow color, and make it feel harsh. A small quantity should be used in heating. A good quality of zinc oxide should come in the form of a soft, flaky, impalpable powder of sp. gr. 5.6. It should turn yellow when heated in a test tube, and become white again on cooling. It is insoluble in water but completely solu- ble in dilute acids. It is not darkened by sulphuretted hydrogen. 201. Zinc Oxyphosphate. By the combi- nation of zinc oxide with phosphoric acid a sub- stance is obtained known familiarly as oxyphos- phate of zinc. As known to dentists it comes in the form of a powder and a liquid. The pow- der is zinc oxide, and the liquid some variety of phosphoric acid. The two mixed, in proper- 128 DENTAL CHEMISTRY. tions, found by trial to be suitable for setting purposes, form the oxyphosphate cement. When glacial phosphoric acid is used, the cement is termed oxy;^phosphate. The ptire glacial phosphoric acid is preferred for use, as cements made from the com- mercial glacial acid have been found less durable.* 202. Zinc Oxychloride. Theoretical constitution: oxychlorides differ from chlorides, in that the former are chlorides of the oxide of a metal, while the latter are chlorides of the metal itself only. There are various oxychlorides of zinc, whose formulae are as follows: (a) ZnCl 2 .6ZnO.6H 2 O; (b) ZnCl 2 .3ZnO.4H 2 O; (*) ZnCl 2 .9ZnO.3H 2 O. It will be seen, therefore, that the general formula for the three is ZnCl 2 7/ZnO.7zH 2 O, n denoting any number. Method of Preparation. The oxychloride is prepared from a powder and a liquid, as in *Rollins's process for making the oxymetaphosphate is as follows: Dissolve pure zinc in C. P. nitric acid to saturation, then evaporate to dryness, pack in a crucible, and heat till no more fumes are given off. Break up the crucible and, after separating the oxide of zinc, pulverize it to a very fine powder. Take a pure solution of orthophosphoric acid (Section 266-1) which can easily be obtained of a strength of sixty per cent.; evaporate it in a platinum evaporating dish till white fumes come off. Then heat it to bright redness to be sure that it is all converted; cool, and make into a thick syrup. To make the filling, mix the powder and fluid in suitable proportions. Slow-setting cements are less durable than those which set more rapidly The powder should be worked into the acid gradually until the mass is stiff, the chief point being not to add too much powder at a time. INORGANIC CHEMISTRY 129 the case of the oxyphosphate. The powder is oxide of zinc, and the liquid a solution of zinc chloride in distilled water.* Properties and uses: zinc oxychloride is a white sub- stance, plastic when first mixed, but rapidly hardening with age. It is used in dentistry for filling, "lining," and restoring color to discolored teeth. 203. Zinc Oxysulphate. Theoretical constitution: the mixture used in dentistry under this name is composed of a powder, consisting of one part of calcined zinc sulphate to two or three parts of calcined zinc oxide. Dissolved in a solution containing gum arabic and a little sulphite of lime, it forms a plastic mass soon setting and very dense when hard. (Flagg). Uses in dentistry: zinc oxysulphate is used in dentistry as an adjunct to filling materials. 204. Other compounds of zinc. Zinc sulphate, ZnSO 4) ;H 2 O: white vitriol, white cop- peras, Zinci Sulphas. Occurs in small, colorless, trans- parent, efflorescent crystals, often mistaken for Epsom salt, astringent, emetic, irritant poison. Freely soluble in water, insoluble in alcohol. Disagreeable, metallic, styp- tic taste. Made by dissolving zinc in sulphuric acid: Zn + H 2 SO 4 = ZnSO 4 + H 2 . *Various methods of preparing the oxychloride have been sug- gested and as the zinc chloride is very soluble in water various strengths of solution have been used, such as 1 part to 2 of water, equal parts, etc., etc. According to Feichtinger (Dingier s Pol. Journal] a good method is to add 3 parts of zinc oxide and 1 part glass powder to 50 parts of a solution of zinc chloride of specific gravity, 1.5 to 1.6 to which is further added 1 part of borax dissolved in the smallest possible quantity of water. Flagg heats oxide of zinc with borax, adds gradually more cal- cined oxide of zinc, and finally mixes with the zinc chloride solution. 130 DENTAL CHEMISTRY. Zinc iodide, ZnI 2 = 318.1. Official name, Zinci lodi- dum. Made by digesting granulated zinc 30 Gm. (465 grains) iodine 100 Gm. (1550 grains) water 200 C. c. (6% fluid ounces) until colorless and free from odor of iodine, subsequently filtering through asbestos or pow- dered glass and evaporating filtrate rapidly to dryness at moderate heat. Zinc iodide is a white, granular substance, very readily soluble in alcohol and in water. Zinc iodo-chloride has also been used in dentistry. Toxicology of zinc compounds: the general antidotes are alkaline carbonates, as sodium carbonate; white of egg, soap and water, and mucilaginous drinks. 205. Cadmium. Symbol: Cd. Latin name: Cadmium. Equivalence: II. Specific gravity: 8.69. Atomic -weight: 112. Mole- cule composed of one atom. Revised atomic weight: 111.835. Electric state: +. Fusing point: 442 F. Length of bar, etc.: 1.0031; (first in rank, most expansi- ble). Wt. of cubic ft. in Ibs.: 542.5. Tenacity: greater than tin. Malleability, Ductility: flexible, malleable, and ductile. Conducting power (electricity): somewhat lower than zinc. Resistance to air: gradually tarnishes in air; stained yellow by sulphuretted hydrogen. Solubility: soluble in nitric acid, in dilute hydrochloric, and sul- phuric, but not in caustic alkalies. Direct combinations: oxygen, chlorine, sulphur. Color and appearance: like tin; white tinged with blue; lustrous. Structure: crystal- izes in regular octahedrons on cooling. Consistence: harder than tin; not so hard as zinc; soft enough to mark paper. Compounds: cadmium, as cadmium sul- phate. Alloys: fusible metal, amalgam alloys. Occurrence: cadmium often accompanies zinc in its ores, and occurs as an impurity in commercial zinc. It is found in small quantities, not over 2 or 3 per cent., in ores of zinc. It occurs most abundantly as sulphide. INORGANIC CHEMISTRY. 131 Preparation: the metal is obtained by converting the sulphide into oxide by heat, and then reducing this with coal or charcoal. Uses in dentistry: cadmium is a constituent of easily fusible alloys. It resembles tin in color and appearance, and creaks like the latter when bent. It is unalterable in the air. It has been used in dental amalgam alloys. 206. Compounds of Cadmium. Cadmium Sulphate: 3(CdSO 4 ). 8H 2 O. Obtained by dissolving metallic cadmium, its oxide, or carbonate in sulphuric acid; if metallic cadmium is used, a little nitric acid is added to hasten the reaction, and afterwards driveri off by evaporation. Cadmium sulphate occurs in form of colorless, transparent crystals, resembling sul- phate of zinc. In dentistry it has been used in various injections and lotions. It is poisonous. Percentage of cadmium, 43.74. 207. Lead. Symbol'. Pb. Latin name: Plumbum. Equivalence: II and IV. Specific gravity: 11.33 to 11.39. Atomic weight: 206.5. Revised atomic weight: 206.4710. Electrical state: -f-. Fusing point: 617 F. Length of bar, etc.: 1.0028 (3d rank, cadmium = I, most expansible). Wt. of cubic ft. in Ibs.: 709.2. Tensile strength: 0.8 to 1.5. Relative tenacity: I (lowest in rank). Malleability: 6; (6th rank). Ductility: 10; (loth rank). Conducting power (heat): 9; (gth rank). Conducting power (electricity): 83; (silver = 1000); ( loth rank). Resistance to air ; etc.: soon tar- nishes; corroded by air in presence of carbonic acid. Dis- colored by sulphuretted hydrogen. Solubility: soluble in dilute nitric acid; attacked by hot sulphuric. Direct combinations: oxygen, chlorine, bromine, iodine, sulphur. Amalgamates readily. Color and appearance: bluish -white, brilliant. Structure: crystallizes in regular octahedrons, or in pyramids with four faces. Consistence: soft, leaves 132 DENTAL CHEMISTRY. mark on paper. Compounds: mostly plumbzV, so-called, Pb". Alloys: solder, type metal, pewter, fusible metal; has affinity for platinum and palladium. Occurrence: lead occurs in nature chiefly as galena or galenite, which, like cinnabar, is a sulphide, PbS; 100 parts of the pure ore con- tain 86^ of lead. Another ore is white-lead ore or carbonate of lead. Galena is found in Great Britain, Spain, Saxony, and the United States. White lead ore is found in the valley of the Mississippi; in Australia, an ore called Anglesite, which is a sulphate of lead, is found. Other ores are crocoisite (a chromate), Wul- fenite (a molybdate), and pyromasphite (a phosphate). Preparation : galena is roasted, during which process two products, lead oxide and lead sulphate, are formed; the two products thus obtained are then strongly heated in a reverberatory furnace, metallic lead and sul- phurous oxide being formed. Dental uses: lead alloys with other metals, and is an ingredient of various solders: com- mon solder is 50 parts lead and 50 parts tin. Lead is used in dentistry chiefly in making counter-dies. [Thin sheets of it are used. for making patterns by which gold or silver plate is cut, so that bits of it may be found in the dentist's gold drawer; a very small amount of it will greatly impair the ductility of gold]. INORGANIC CHEMISTRY. 133 Compounds of lead: oxides of lead are used as coloring matters for artificial teeth. Plum- bic peroxide (dioxide) PbO 2 , is a chocolate- brown or puce-colored powder, which gives off its oxygen on being- heated. Litharge is plumbic oxide, PbO, prepared by heating melted lead in a current of air. It is pale yellow or orange yellow in color. By oxidizing litharge in a current of air and cooling slowly, a substance used in the arts as a pig- ment and called plumbic meta-plumbate, Pb n Pb IV O 3 , or Pb 2 O 3 , is formed. The plumbic plumbates form the sub- stances known as red-leads. 208. Compounds of Uranium. An oxide of uranium is used by dentists as a coloring matter for artificial teeth.* Its formula is U 2 O 3 , uranic oxide, or uranyl oxide as it is sometimes called. Uranic nitrate heated in a glass tube till it decomposes yields pure uranic oxide in the form of a yellowish pow- der. Another oxide of uranium is uranous oxide, UO, a brown powder. 209. Copper. Symbol: Cu. Latin name: Cuprum. Equivalence: (Cu 2 ) n and II. Specific gravity: 8.914 to 8.952. Atomic weight: 63.2. Revised atomic weight: 63.173. Electrical state: -}-. Fusing point: 1996F. Length of bar, etc.: 1.0017; (7th in rank). Weight of cubic foot in Ibs.: 558.1. *Rollins uses such oxides as contain the most oxygen, that is, uranic rather than uranous, plumbic dioxide rather than protoxide, etc., etc., because the coloring matters sometimes lose oxygen in firing. 134 DENTAL CHEMISTRY. Tensile strength: 13 to 15. Tenacity: 18, (Lead = i); (3d rank). Malleability: 3; (3d rank). Ductility: 5; (5th rank). Conducting power (heat): 3; (3d rank). Conducting power (electricity): 999, (Silver = 1000); (2d rank). Re- sistance to air, etc.: in moist air becomes coated with green carbonate. Tarnished by sulphuretted hydrogen. Solu- bility: soluble in hot mineral acids, and attacked by vegetable acids in presence of air and moisture. Attacked by chlorine and nitric acid, and by sulphur when heated; slowly attacked by weak acids, alkalies, and saline solu- tions. Direct combinations: sulphur, chlorine, bromine, iodine, silicon, and various metals at red heat. Color and appearance: lustrous, flesh red. Structure: crystal- lizes in isometric forms. Consistence: somewhat softer than iron. Compounds: cuprous (Cu 2 ) u and cupric. Alloys: Aich's metal, aluminium bronze, arguzoid, bell- metal, brass, Britannia metal, bronze, Dutch-metal, electrum, German silver, gold coinage, gun-metal, Muntz's metal, pewter, silver coinage, some solders, speculum metal, sterro-metal, tutenag. Occurrence: native copper exists near Lake Superior; in its ores it is found as oxide, sul- phide, carbonate, and in combination with sul- phide of iron, forming copper pyrites. The metal is found in "England, Sweden, Saxony, Siberia, Australia, Chili, and in the United States. Preparation: the ores are first roasted in air, then with silica fluxes and carbon, and finally a substance called copperstone is obtained, which contains both oxide and sulphide of cop- per. By repeating the roasting and heating, INORGANIC CHEMISTRY. 135 the oxide reacts on the sulphide, and metallic copper is obtained. Pure Copper may be obtained by electroly- sis. A solution of cupric sulphate is used, and the negative wire of a battery attached to a copper plate which is immersed in the solution. Pure copper is deposited on the plates, and may easily be stripped off. Use in dentistry: copper is used as a con- stituent of some dental amalgam alloys.* Alloys of Copper : Babbitt Metal is an alloy of copper, 3 parts; antimony, I part; tin, 3 parts. The copper is fused and then anti- mony and tin are added to it. It melts at a moderately low heat; contracts but little; is brittle, but may be render- ed less so by adding tin. 210. Brass is an alloy of copper and zinc. Common brass is made of 66.6 parts copper and 33.3 zinc; best brass, 71.4 copper to 28.6 zinc. Yellow brass is 60 copper to 40 zinc. Brass melts at 1869 F. 211. Bell metal is an alloy of 6 parts copper to 2 parts tin; some varieties are 78 copper to 22 tin. Cannon metal is 90 copper to 10 of tin. 212. Bronze is an alloy of copper and tin. Aluminium bronze, 900 parts copper to 100 of aluminium. The lat- ter has been used for the under layer of teeth plates, and is said to be free from injurious oxidation and to be more easily manipulated than gold alloys or silver. It may be stamped and pressed, almost as easily as pure silver, while possessing the elasticity of steel. Its melting point is higher than that of pure gold, so that it may be made red hot without danger of melting, and can be manipulated *See Copper Amalgam under Mercury. 136 DENTAL CHEMISTRY. with hard solder. Sauer solders it with from 14 to 16 carat red gold. Aluminium bronze is one-half lighter than 12 carat silver and almost half the weight of 14 carat gold. It oxidizes, superficially only, in the mouth; it is affected, superficially, by a I in 1,000 solution of corrosive sublimate, but not by carbolic acid. 213. Gold aluminium bronze oxidizes more readily, is softer, and not so elastic. 214. Phosphor bronze is copper, combined with from 3 to 15 per cent, of tin, and from % to 2 ^ P er cent, of phosphorus. 215. Speculum metal is an alloy of copper and tin; 66.6 copper and 33.3 tin. 216. Compounds of Copper. Cupric Sulphate: CuSO t , 5H 2 O. Known as sulphate of copper, blue vitriol, Roman vitriol, blue stone, blue copperas, vitriol of copper. Official name, Cupri Sulphas. Made on a large scale by dissolving copper in sulphuric acid, evaporating, and allowing to crystallize: Cu + 2H 2 SO 4 = CuSO< + 2H 2 O + SO* Copper sulphuric acid cupric water sulphurous sulphate oxide It occurs in the form of blue, prismatic crystals, efflor- escent, of astringent, metallic taste, soluble in 4 parts water, insoluble in alcohol. In dentistry it is used exter- nally, dissolved in ammonia, as an astringent and styptic. it is poisonous; antidotes: milk, white of egg given freely. 217. Mercury (quicksilver). Symbol: Hg. Latin name: Hydrargyrum. Equivalence: (Hg 2 ) u and II. Specific gravity : 13.596. Atomic weight: 199.7. Molecule composed of one atom. Revised atomic weight: 199.7120. Electrical state: -f-- Fusing point: liquid at ordinary temperatures. Boils at 660 F. Length of bar total expansion, 1.0180. Malleable at 40 F. Resistance to air, etc.: unaltered in air; does not leave streak on paper. INORGANIC CHEMISTRY. 137 Solubility : soluble in dilute nitric acid and hot sulphuric; insoluble in hydrochloric acid. Direct combinations: dis- solves all metals but iron; combines directly with halogens and sulphur. Color and appearance: opaque, with metallic lustre; brilliant silver- white. Structure: octahe- dral crystals at 40 F. Consistence: liquid; slightly volatile. Compounds: mercurous (Hg 2 ) n and mercuric. Alloys: amalgams. Use in dental amalgam alloys: mer- cury amalgamates readily with gold, zinc, tin, and silver; also with copper, platinum, palladium, and cadmium. Occurrence and preparation: mercury is found in the form of Cinnabar, which is native mercuric sulphide. Large quantities of it are obtained in California; it is also found in Spain, Austria, Mexico, Peru, China, Japan, Borneo. Mercury is obtained from cinnabar, either by roasting the latter or by heating it with lime, which combines with the sulphur of the cinnabar, while the metal volatilizes and is condensed in suitable coolers. The equation of the preparation of mercury is HgS + 2O Hg + SO 2 Mercuric Oxygen. Mercury. Sulphurous sulphide. oxide. Dental uses: amalgams. Mercury readily alloys with other metals, forming combinations called amalgams. This property of mercury may be readily shown by the following experiment: clean a copper cent with a little nitric acid, wash well with wateV, and on it place a globule of mer- 138 DENTAL CHEMISTRY. cury; the latter soon covers the whole surface of the cent, giving it a white color. Heat the cent and its original color will be restored, the mercury volatilizing. Many of the alloys of mercury with other metals are soft when fresh- ly formed, but harden with time, hence their value for fillings. The combinations formed are, in the case of solid amalgams, definite compounds in which, however, there is but feeble chemical affinity between the constituents. Liquid amalgams are merely solutions of the various metals in mercury, and not, as a rule, definite chemical compounds. Many liquid amalgams become, however, after a time, white, solid, and crystalline. There is usually little or no contraction in volume, but in the case of silver and copper amalgams there is considerable, and in tin and lead slight, though perceptible. (Watts). Amalgams are decomposed by heat. 218. The methods by which amalgamation may be made to take place are as follows: 1. Direct contact on part of the metal, either as a solid or in the finely divided state, with mercury, either at ordinary temperatures or at higher temperatures. Heat is evolved during the amalgamation. 2. Introduction of metallic mercury, or of sodium-amalgam, into a solution of a salt of a metal. 3. Introduction of a metal into a solution of a salt of mercury. 4. Contact of a metal with mercury and addition of a dilute acid. INORGANIC CHEMISTRY. 139 In the last two cases a weak electric current is sometimes developed. Electricity is often used to facilitate the union of mercury with a metal precipitated from a solution of one of its salts. (See Copper Amalgani}. 219. Antimony amalgam: triturate 3 parts heated mer- cury with i part fused antimony; or triturate 2 parts anti- mony in a mortar, add a little hydrochloric acid, and gradu- ally drop in I part of mercury. The amalgam is soft, de~ composed by contact with air or water, and the anti- mony separates. Amalgams containing antimony in notable quantity are fine grained, plastic, and do not shrink, but are excessively dirty to work. Used in small proportions in amalgams it is said to be of possible value in controlling shrinkage.* 220. Cadmium amalgam: cadmium amalgamates at ordinary temperatures. When complete saturation takes place, as through agency of sodium-amalgam in a solution of salt of cadmium, a compound of 78.26 Hg to 21.74 Cd is formed, having- for its formula, therefore, Hg 2 Cd, and being silver-white, granular, hard, brittle, heavier than mercury, and in octahedral crystals. (Watts). Cadmium amalgamates easily, sets quickly, and resists sufficiently, but fillings containing it gradually soften and disintegrate, and, if there is a large proportion, the den- tine becomes decalcified and stained bright orange-yellow from formation of cadmium sulphide. 221. Copper amalgam: there are various processes *Dr. Chase's " alcohol tight " amalgam contains nearly five per cent, of antimony. (Weagant). 140 DENTAL CHEMISTRY. for making copper amalgam. Rollins, Ames, and others make it by electrolysis. Rollins's method is as follows:* Distilled water, five gallons; sulphate of copper, enough to saturate; sulphuric acid, one pound. Mix, filter, and pour into a wooden firkin with wooden hoops. All the chemicals should be absolutely pure. Place ten pounds of pure mercury in a glass jar and immerse in the copper solution. To the zinc plate of a galvanic battery attach a gutta-percha-covered wire, having one end bare for about an inch. This exposed end is to be immersed below the level of the surface of the mercury. Tie granulated pure copper in a bag and hang it in the copper solution, con- necting with a wire to the carbon of the battery. The battery is to be kept in action till the mercury has ab- sorbed enough copper to make a thick paste. Then remove and wash thoroughly in hot water till all of the sulphate solution has been removed. Squeeze out the softer amalgam and allow the remainder to harden. When it is hard, heat it, and renew the squeezing as before. This new method insures an amalgam of perfect purity, and is simpler than any of the old and faulty ways in use. Copper amalgam dissolves rapidly in mouths where the saliva is acid, and in this way serves as an indicator of the condition of the oral fluids. It stains teeth in a certain proportion of cases, particularly when teeth have lost their pulps, or when the dentine is of an open structure. A battery answers for home manufacture, but on a larger scale a dynamo should be used. Dr. T. H. Chandler, of Boston, has described to me the following processes for making copper amalgam, which he calls ' No. i" and "No. 2." He thinks "No. i" an excellent filling: * Boston Medical and Surgical Journal, February, 1886. INORGANIC CHEMISTRY. 141 No. I. To a hot solution of sulphate of copper add a little hydrochloric acid, and a few sticks of zinc, and boil for about a minute. The copper will be precipitated in a spongy mass. Take out zinc, pour off liquor, and wash the copper thoroughly with hot water. Pour on the mass a little dilute nitrate of mercury, which will instantly cover every particle of the copper with a coating of the mercury. Add mercury two or three times the weight of the copper, triturate slightly in a mortar and finish by heating the mixture a few moments in a crucible. No. 2. Take finely divided copper (copper dust) ob- tained by shaking a solution of sulphate of copper with granulated tin. The solution becomes hot, and a fine brown powder is thrown down. Of this powder take 20, 30, or 36 parts by weight and mix in a mortar with sul- phuric acid, 1.85 specific gravity, to a paste, and add 70 parts of mercury with constant stirring. When well mixed, wash out all traces of acid and cool off. When used, heat to 1300 F; it can be kneaded, like wax, in a mortar. While in this plastic state, it is an excellent solder for metals, glass, etc., used by applying it to surfaces to be joined, pressing hard together and allowing it to set. Weagant's process for making copper amalgam is as follows: Nearly fill a vessel with a solution of copper sulphate, one part of a saturated solution to two or three parts water. Pour into it enough mercury to cover well the bottom of the glass, and stand a clean strip or plate of iron in the mercury, allowing the end to project above the glass. Pure precipitated copper in finely divided state will at once become deposited on the iron, and the mercury will gradually unite with the copper, creeping up the iron until the whole surface is covered with a film of amalgam. If the iron is placed for a moment in a weak solution of sulphuric acid just before being immersed in the copper bath, amalgamation takes place more rapidly. 142 DENTAL CHEMISTRY It must be allowed to stand undisturbed until the change in the color of the solution shows that all the copper is precipitated. Then with a siphon draw off the liquid and renew the sulphate of copper. This proceeding may be repeated as long as the mercury takes up the copper. When all the mercury has become amalgamated, scrape off whatever amalgam adheres to the strip of iron, pour off the liquid, and turn the mass of amalgam into a mor- tar. Rub and wash it thoroughly, allowing a stream of water to fall upon it from a tap, cleaning out all the free metallic copper and scales of oxide of iron. As soon as it is as clean as it can be made, place it in a chamois skin and squeeze out the surplus mercury. Then the washing and grinding in the mortar must be repeated until the mass again becomes soft, when more mercury can be re- moved. The greatest care must be taken to remove all the little scales and grains of iron, or the amalgam will be dirty to work, and the best results from it cannot be obtained. When the amalgam has been well worked and all the mercury possible squeezed out, heat it gently in an iron vessel. The first time this must be done carefully, as steam from water which is retained in it becomes generated, and the mass will explode, flying in all direc- tions. When the amalgam begins to get soft, rub in a mortar, and again squeeze out mercury. This heating, rubbing, and squeezing must be repeated again and again, until very little mercury can be removed and the amalgam is found to set instantly, and become very hard. It may then be made into little sticks or pellets, and laid away for use. To use it, place the quantity required in an iron spoon and heat it over a flame until mercury begins to show like sweat upon the surface. Then crush and grind the mass in a small mortar, and work together in the hand. If too soft, squeeze in a piece of chamois skin, using a pair of pliers if necessary. One soon learns how soft or INORGANIC CHEMISTRY. 143 dry to make it in order to get the best results. Do not throw away any of the scraps remaining, as they may be used over and over again an indefinite number of times, seeming to improve by age. Be careful not to heat too much, as some of the mercury volatilizes, leaving pure copper, which becomes oxidized by the heat and makes the amalgam dirty. A weak solution of sulphate of copper is used instead of the saturated solution, as the precipitate is much finer and the amalgam requires less rubbing to bring it to shape. Copper amalgam is composed of pure copper and pure mercury in variable proportions. The less mercury it contains the more quickly it sets and the harder it be- comes. When properly made it is exceedingly pleasant to work, fine-grained and plastic, and sets either slowly or rapidly, as we desire it and are pleased to prepare it. It becomes very hard harder in fact than any amalgam made from alloys. It is not known to shrink or expand in the least degree. It does not ball up nor change its shape in any way during the setting or afterwards, and finally, instead of having any injurious effect upon the teeth or surrounding tissues, it is decidedly beneficial to them, acting as an antiseptic or germ destroyer. But, al- though it does not cause discoloration of the teeth, the filling itself will quickly and emphatically become black very black upon the surface. It should always be carefully polished when hard, for, although polishing does not prevent its turning black, it is a polished black, and not so disagreeable and dirty looking as when left with a rough surface. (Weagant). The sulphide of copper formed by the action of the sulphuretted hydrogen of the mouth on the copper of the amalgam is, according to Tomes, readily converted, on exposure to air and moisture, into copper sulphate, hence 144 DENTAL CHEMISTRY. it is almost certain that the latter is formed on the ex- posed surface of the filling. Cupric sulphate is freely soluble, and hence is likely to permeate the dentine. Sulphides of the other metals are not so readily converted into soluble salts, hence will not permeate the dentine so thoroughly.* 222. Gold amalgam: gold, in leaf or filings, amalga- mates readily with mercury at ordinary temperatures. For rapid amalgamation, heat should be used, and the gold be in the finely divided state. Gold added to amalgams of tin and silver is valuable in that it controls shrinkage, balling, and discoloration, facilitates setting, and adds to edge-strength. Amalgams containing* it are smoothly and easily worked. Some dentists use amalgams containing a very large proportion of gold. 223. Palladium amalgam: Palladium has been recently brought to notice as form- ing with three times its weight of mercury a desirable dental amalgam, especially useful in the sixth-year molars of young patients.f Some care is necessary in the mixing, as palladium forms a true chemical compound with mercury, and the action is so intense that under certain circumstances an explosion may result. Palladium fillings become black, but do not discolor the tooth-substance. The amalgam sets with such great rapidity that it is necessary to mix it quite soft in order to make a filling *Copper sulphate has been successfully used abroad as a preserva- tive for telegraph poles. fDr. E. A. Bogue has used palladium amalgam. In the proportion of seventy-five per cent, mercury to twenty-five per cent, of pure pre- cipitated palladium the expense is greatly reduced. INORGANIC CHEMISTRY 146 before it is too hard to use.* It must be worked very quickly, and with heated instruments. 224. Platinum amalgam: metallic platinum does not unite readily with mercury. Spongy platinum unites with mercury, when triturated in a warm mortar with the lat- ter, or in contact with acetic acid; or sodium-amalgam containing I percent, sodium, if introduced into a solution of platinic chloride, will form an amalgam of silvery ap- pearance. The amalgam containing 100 parts mercury, to 15.48 platinum, has asp. gr. of 14.29, and has metallic lustre when rubbed; 100 mercury to 21.6 platinum is a dark gray solid; 100 mercury to 34.76 platinum is of 14.69 sp. gr., dark gray, but of no lustre; 100 mercury to 12 platinum is bright, but soft and greasy. The solid amal- gam containing the most mercury is probably PtHg 2 . Mercury exposed for some time to the action of platinic chloride forms a thick, pasty amalgam. In general, it may be said that an amalgam of mercury and platinum alone does not harden well.f Platinum, according to Essig, is of value only when com- bined with tin, silver, and gold, with the proper amount of mercury; under such circumstances, it seems to confer on the alloy the property of almost instantly setting, and of being much harder. According to Fletcher, the amal- gam should be used immediately, before the platinum and mercury have time to set. 225. Silver amalgam: amalgamation takes place quickly, if the silver is in thin plates, or in powder, and dropped at red heat into heated mercury. The amalgam varies according to circumstances of formation, composi- tion, etc., and is soft, or crystalline, or granular. The *Dr. Chandler mixes gold in large proportion in order to render the palladium more tractable. tDr. Ames, of Chicago, has prepared platinum amalgam by electrolysis. 146 INORGANIC CHEMISTRY. amalgam most readily formed has for its formula AgHg. [Amalgams of mercury and silver are said by Watts to contract considerably, but by others to expand. The proportions are undoubtedly of importance]. Amalgams composed of silver and mercury alone tend, when used as fillings, to change their shape. But silver used in connection with other metals is the most import- ant element in a good amalgam for filling teeth.* Silver forms silver sulphide in contact with the sulphuretted hydrogen of the mouth, and both tooth and filling are blackened in consequence; but the tendency is toward preservation of the tooth. 226. Tellurium and mercury are said to unite directly, forming a tin-colored amalgam. 22-7. Tin amalgam: made readily and quickly by pouring mercury into melted tin, but readily enough by mixing the filings with mercury at ordinary temperatures. Tin amalgam has a white color, and, if there is not too much mercury, occurs in form of a brittle, granular mass of cubical crystals. In most cases there is condensation, but in the amalgam composed of I part tin to 2 mercury (melted and by volume) the condensation is scarcely perceptible. Amalgams composed of mercury and tin alone do not harden sufficiently. In an alloy with other metals, tin is valuable in that it facilitates amalgamation, prevents dis- coloration, and diminishes conductivity. 228. Zinc amalgam: usually made by cooling melted zinc to as low a temperature as possible without letting it solidify, then pouring in mercury in a fine stream, and stirring constantly. Amalgams of mercury and zinc alone are not common- *Silver is the largest component of most of the reliable amalgam alloys on the market. INORGANIC CHEMISTRY. 147 ly used. Added to alloys of tin and silver in as small proportion as one per cent., zinc controls shrinkage, adds to the whiteness of the filling, and tends to maintain color.* 229. Dental amalgam alloys : it will readily be per- ceived from a study. of common amalgams that but few of them would be of service to the dentist. On the other hand combinations of metals, often first melted in tin, brought about through the agency of mercury that is, amalgams of several metals at once, alloy amalgams have been found very useful, so that now large quantities are used. Amalgams for dental purposes are chiefly com- posed of tin and silver, in different proportions, of which Townsend's alloy of 60 tin to 40 silver may be taken as the type. Some dental amalgam alloys, as Hardman's and Lawrence's, contain copper in addition to tin and silver; some contain zinc, gold, etc. The list of metals used in the dental amalgam alloys comprises tin, silver, copper, zinc, gold, platinum, cadmium, antimony, palladium. The so-called " gold and platina alloys," according to Flagg, contain 50 per cent, of tin, more than 40 of silver, and from 2 to 7 of gold and platinum. [In regard to the average proportions of tin and silver, Flagg finds 40 tin to 60 silver the best working formula, modified by additions of copper, gold, and zinc]. 230. Qualities desirable in dental amalgam alloys: strength and sharpness of edge, freedom from admixture with any metal favorable to the formation of soluble salts of an injurious character in the mouth, capability of maintenance of color and shape, and non-liability to undue expansion. N. B. Absolute freedom from dis- coloration can not .often be obtained, nor is it always desirable, according to Flagg. *Chandler's experiments with zinc lead him to prefer sifting in a small percentage oipitre zinc dust at the "mix" rather than melt- ing it with the other ingredients of an amalgam alloy. 148 DENTAL CHEMISTRY. 231. Discoloration of amalgam fillings: the forma- tion of sulphides, due to the sulphuretted hydrogen resulting from the decomposition. of the food, is the main cause of the discoloration of amalgam fillings; -black dis- coloration is found in fillings containing silver or copper; yellowish discoloration in those containing cadmium. According to Essig, it is not safe to suppose that a metal not of itself blackened by sulphuretted hydrogen as gold or platinum will secure the same immunity to alloys containing silver and mercury. It has been noticed that plugs, which apparently exclude the passage of a solution of indigo or ink, will show peripheral discoloration when exposed to the action of a sulphuretted hydrogen solu- tion, though the surface directly exposed to the action of the sulphur was but slightly clouded.* (Essig). Discoloration of gold fillings: Chandler takes the ground that the discoloration of gold in the mouth is due to oxidation of the steel worn from pluggers. 232. Compounds of Mercury: Mercuric chloride or corrosive sublimate: Synonyms: corrosive chloride, bichloride of mercury, " oxymuriate " of mercury, perchlor- ide of mercury, deuto-chloride of mercury, Hydrargyri Perchloridum. Official name, Hydrargyri Chloridum Corrosivum. Theoretical constitution: HgCl 2 or mercuric chloride. Mercury as a dyad. The molecule is composed of one atom of mercury to two of chlorine; by weight, mercury 200 parts, chlor- *Chandler suggests that the discoloration and destruction of amalgam fillings may be due to galvanic action, the ingredients of fillings forming minute batteries, as it were, and destroying one another. INORGANIC CHEMISTRY. 149 ine 70.8. Molecular weight, 270.8. Percentage of mercury, 73.85. Preparation (pharmaceutical): made by tak- ing 20 parts of mercuric sulphate and 16 of sodium chloride, reducing each to fine powder, mixing well, adding i part of black oxide of manganese in fine powder, triturating thor- oughly in a mortar, and subliming: HgSO, + 2NaCl = HgCl 2 + Na 2 SO 4 . Mercuric Sodium Mercuric Sodium sulphate. chloride. chloride. sulphate. The manganese oxide is added to oxidize any mercurous salt which may be present in the mercuric sulphate. Properties: corrosive sublimate occurs as a white, heavy powder, or as heavy, colorless, rhombic crystals or crystalline masses. It has a metallic, acrid taste, an acid reaction, and is a violent poison. Specific gravity, 5.4. It is soluble in 16 parts of cold water, and 2 of boil- ing, in about 2 of alcohol, and 4 of ether. Its ready solubility in alcohol should be noted, as many compounds of the metals are insoluble in alcohol, or less soluble in it than in water. It is a powerful germicide, an aqueous solution of i in 20000 destroying the spores of bacilli in ten minutes. A solution of i in 5000 is used as a disinfectant. Aqueous solutions gradually decompose on exposure to light, or in contact with organic substances, such as sugar, gum, extracts, resin, etc. When mercuric chloride 150 DENTAL CHEMISTRY. is being powdered, it should be kept moist with alcohol to prevent the poisonous dust from rising. Dental uses: mercuric chloride in i in 20000 solution half a grain in twenty-one fluid oun- ces of water (metric, 0.032 grammes in 620 C.c.) is used as an antiseptic. As a germicide, i part in 2500 of water; i in 5000 as a disinfectant. It is used as a lotion, injection, or gargle. Toxicology: corrosive sublimate is a power- ful, irritant poison, and external application of it has been often attended by fatal results. In poisoning from internal administration, white of egg in milk, or else wheat flour mixed with milk, should be given; vomiting should be encouraged by emetics. White of egg in milk should be administered two or three times daily for some weeks. If salivation is trouble- some, gargles of chlorate of potash and of alum should be used. In chronic poisoning, ptyalism is a prominent symptom. In chronic mercurial poisoning the teeth are said to become brittle. 233. Mercurous chloride or calomel: Synonyms: mild chloride of mercury, subchloride of mercury, submuriate of mercury, Hydrargyri Subchlori- dum, protochloride of mercury. Official name, Hydrar- gyri Chloridum Mite. Theoretical constitution: Hg 2 Cl 2 , two atoms of mercury (together bivalent) and two of chlorine; 400 parts by weight of mercury.and 70.8 by weight of chlorine. Mole- INORGANIC CHEMISTRY. 151 cular weight, 470.8. Its formula is sometimes written HgCl. Preparation: either (i) by subliming mercuric sulphate 10 parts with sodium chloride 5 parts, 7 parts of metallic mercury having been previously triturated with the moist- ened mercuric sulphate. HgSO, + Hg = Hg 2 S0 4 ; then Hg 2 SO 4 + 2NaCl = Hg 2 Cl 2 + Na 2 SO 4 . Mercurous sulphate and sodium chloride yield mercurous chloride and sodium sulphate. Or (2) by precipitating by hydrochloric acid a solution of 300 grams of mercury in 270 C.c. of suitably diluted nitric acid. Properties: sublimed calomel is a fine, white powder with very slight tinge of yellow. Tasteless, insoluble in both water and alcohol. Sp. gr., 6.56. Completely volatilized by heat. Precipitated calomel is bulkier than sublimated calomel. Exposed to sunlight, it acquires a grayish tinge becoming partially decomposed into metal- lic mercury and corrosive sublimate; boiled with water, the same change takes place slowly, and a mixture of it with sugar contains, after some time, an appreciable amount of the mercuric chloride. Mixed with water, it should give no white precipitate with ammonia. Given internally in sufficient quantity it produces salivation; cases are also on record where external application of it has produced salivation. 234. Mercuric Sulphide. Synonyms: sulphide of mercury, cinnabar, vermilion. Theoretical constitution : HgS, mercur/^ sulphide. Molecular weight, 231.7. Preparation: it occurs as an ore and is then termed cinnabar. Made artificially, it is called vermilion. 152 DENTAL CHEMISTRY. The brilliancy of vermilion depends much on the manner in which it is prepared, and on the purity of the substances used in making" it. One method of preparation is to heat to I22F. the following mixture: mercury, 300 parts; sul- phur, 114 parts; potassium hydrate, 75 parts; water, 450 parts. The presence of potassium hydrate facilitates the reaction. The mass, which is at first black, becomes red in the course of several hours; in order to cool it, it is poured into cold water, collected on a filter, washed, and dried. Several kinds of vermilion are found in commerce; the Chinese (made in the dry way by subliming a mixture of sulphur i part and mercury 7 parts in small lots) the German, and the French. Vermilion should sublime without residue, if pure.* 235. Mercuric Iodide. Synonyms: biniodideof mercury, red iodide of mercury, deut-iodide of mercury. Official name, Hydrargyri lodidum Rubrum. Theoretical constitution: HgI 2 , mercuric iodide. Mole- cular weight, 453.2. Preparation: formed when solution of potassium iodide is cautiously added to solution of mercuric chloride, HgCl 2 + (KI) 2 HgI 2 '+ 2KC1. Mercuric Potassium Mercuric Potassium chloride. iodide. iodide. chloride. Properties: occurs as a fine, heavy, crystalline, scarlet- red powder. Nearly insoluble in water, but soluble in hot alcohol, in solution of potassium iodide and of sodium chloride. Is a powerful irritant poison. *Shown by heating dry in a tube called a reduction tube. INORGANIC CHEMISTRY. 153 236. Mercurous Iodide. Synonyms: protiodide of mercury, yellow iodide, green iodide. Theoretical constitution: Hg 2 O 2 or Hgl (like HgCl). Preparation: made by triturating together with a little alcohol 127 parts of iodine and 200 of mercury. Hg 2 + I, Hg 2 I 8 The trituration is continued until there is obtained a green mass, which, after washing in boiling alcohol, is dried. Properties: mercurous iodide is a green-yellow powder, insoluble in water, alcohol, and ether. Exposed to the action of light, heat, alkaline chlorides or iodides, it is transformed into mercury and mercuric iodide. 237. Tellurium. Symbol: Te. Latin name: Tellurium. Equivalence: II, IV, VI. Specific Gravity: 6.18 6.24. Atomic weight: 128. Revised atomic weight: 127.960. Electrical state: Fusing point: little below red heat. Malleability, ductility: brittle. Conducting power (heat): bad' conductor. Con- ducting power (electricity): bad conductor. Solubility: soluble in hot sulphuric acid, in hot caustic alkali solu- tions; attacked by hot nitric acid. Direct combinations: hydrogen, oxygen, sulphur, bromine, chlorine, iodine. Color and appearance: silver white. Structure : crystallizes in rhombohedrons; like As and Sb. Consistence: hard and brittle. Compounds : tellurides; telluric, tellurous. Properties and preparation: tellurium is in physical properties a metal, though chemically allied closely to sulphur and selenium. It is found native, though, in Hungary, and in combination with bismuth, lead, gold and silver. It melts at 500 C. When heated in the air it takes fire and burns with a blue flame tinged with green. 154 DENTAL CHEMISTRY. 238. Sulphur. Symbol; S. Atoms in molecule-, S 2 and S 6 . Atomic weight 32. Molecular weight: 64. Density, of vapor,32. Specific gravity. 2.04. Weight of one litre of vapor: 2.86 grammes at 1000 C. How liquefied: melts at H4C (237 F.) Solubility. insoluble in water. Best solvent: carbon disulphide. Nearly insoluble in alcohol. Occurrence in nature: occurs free in earth of volcanic regions of Sicily. How made: distill crude brimstone in retort; vapor conducted into large chamber condenses in form of pow- der known as flowers of sulphur. Sulphur lotum is flowers of sulphur which has been washed. Sulphur may be made by precipitation from sulphides by acids. Properties: affinity for many of the metals, for oxygen, carbon, etc. Forms many compounds. Lemon yellow solid, melting at 234 F., and boiling at 824 F. Brittle, tasteless, odorless. Does not conduct electricity or heat. Precipitated sulphur is almost white in color. Use in dentistry: flowers of sulphur is used in the manufacture of dental rubbers, as a vulcanizing material. Caoutchouc is heated till soft, then ground with 15 or 20 per cent, of sulphur and subjected to heat, pressure, and moisture. Sulphurous acid: this substance, H 2 SO 3 , is made by dissolving sulphurous anhydride, SO Z , in water. [Sul- phurous anhydride is made by burning sulphur and col- lecting the fumes]. Sulphurous acid is an unstable liquid of suffocating odor. Its compounds are sulphites. It is used for bleaching purposes, and should always be freshly prepared. 239. Hydrogen Sulphide or Sulphuretted Hydrogen. INORGANIC CHEMISTRY. 155 Synonyms: hydric sulphide, sulphydric acid, hydrosulphuric acid, Acidum Hydrosulphuri- cum. Theoretical constitution: H 2 S, two atoms of hydrogen to one of sulphur; by weight, 16 parts of sulphur to i of hydrogen; molecular weight, 34 ; density, 17.2 ; sp. gr., 1.192. Weight of a litre, 1.540. Origin and manufacture: it is found in vol- canic gases, in some mineral springs, and as a result of the decomposition of organic matter containing sulphur, as in the intestines and in teeth. It is usually made by the action of a dilute acid on a sulphide, as for example: FeS + H 2 S0 4 - FeSO 4 + H 2 S Ferrous sulphide. Sulphuric acid. Ferrous sulphate. Hydrogen sulphide Properties: colorless, fetid gas, combustible, soluble in water, readily recognized by its odor, (that of rotten eggs) valuable as a re-agent, yields precipitates with salts of many metals. Blackens unsized paper saturated with solution of sugar of lead. Poisonous. Application to dentistry: its odor, if recog- nized in the breath, indicates that decomposi- tion is going on somewhere in the mouth. Its action on the various metals and com- pounds used in dentistry is of the utmost im- portance. It forms sulphides with silver, mercury, lead, copper, bismuth; these sulphides are all dark in color, and the blackening ob- 156 DENTAL CHEMISTRY. served in amalgam fillings is due to formation of them. It also forms sulphides with arsenic, antimony, cadmium, and tin, but these sulphides are not black; the sulphide of arsenic is yellow, that of antimony orange, cadmium yellow, tin yellow or brown. Sulphuretted hydrogen does not act on metallic gold, platinum, palladium, iridium, nor does it blacken iron, cobalt, nickel, manganese, zinc, chromium, or aluminium. 240 Hydrogen Sulphate or Sulphuric Acid. Synonyms: hydric sulphate, oil of vitriol, dihydric sul- phate, vitriol, spirit or essence of vitriol. Theoretical constitution: H 2 SO 4 , hydrogen sulphate, an oxacid composed of two atoms of hydrogen, one of sul- phur, and four of oxygen; by weight two parts hydrogen, 32 of sulphur, 64 of oxygen. Molecular weight, 98. Its salts are sulphates; for example, zinc and sulphuric acid form zinc sulphate. Preparation: the crude acid is prepared by the action of nitric acid on sulphurous oxide producing sulphuric oxide, which uniting with water forms sulphuric acid. The sul- phurous oxide may be made by burning sulphur in air The acid is concentrated by evaporation until a sp. gr of 1.84 is obtained, when it contains about 96 per cent. o pure sulphuric acid. Properties : coloriess, odorless, heavy, oily liquid. Generates heat on addition of water Very caustic. Stains fabrics reddish, and chars organic matter. Stain removed by ammonia. Valuable for drying gases on account of its affinity for moisture. Sp. gr. (pure) 1.848; official, 1.843. The charring of organic matter by sulphuric acid is due to the fact that it unites with the hydrogen and oxygen INORGANIC CHEMISTRY. 157 in them, leaving behind compounds so carbonaceous that the black color predominates. It corrodes animal tissues. Starch or cellulose boiled with dilute sulphuric acid is converted into glucose, cane sugar into levulose and glucose. Sulphuric acid dissolves most of the metals, but has little action on lead. Acidum sulphuncum, U. S. P., called the C. P. acid, sp.gr. 1.84. Contains at least 96 per cent, of H 2 SO 4 . Acidum sidphuricum dilutum, U. S. P., sp. gr., 1.067; J P ar t of sulphuric acid by weight to 9 parts of distilled water. Acidum sidphuricum aromaticum, about same strength as dilutum', contains alcohol, cinnamon oil, and tincture of ginger. Application to dentistry: in the dental labor- atory the acid is used for cleaning metallic plates previous to soldering and after soldering;. Its action is more vigorous when it is diluted with water, say with about one-third of water, heat being generated. Its action on hemp paper is to reduce it to pyroxylin, hence it is used in the preparation of celluloid base. In dental therapeutics, in dilute form, it is used as a local application in various affections of the mouth. It is caustic, and will dissolve thin, carious portions of bone. Toxicology: the concentrated acid (or the dilute in large doses) is a corrosive poison. Its stain on cloth is usually a dirty brown or reddish brown, and the cloth be- comes rotten and damp. It chars wood. Vomited mat- ters will contain a brownish-colored, bloody liquid with free acid. The treatment is to give lime, magnesia, sodium carbonate, preferably in milk. The stomach pump should not be used in cases of poisoning from acids. Burns 158 DENTAL CHEMISTRY from the acid should be treated like those of hydrochloric acid. 241. Oxygen. Symbol: O. Atoms in molecule: O2. Atom- ic weight: 16. Molecular weight: 32. Den- sity: 16. Specific gravity: 1.10563, (air==i). Weight of one litre of gas: 1.43 grammes. How liquefied: pressure of 300 atmospheres and temperature of 140 C. Solubility: water dissolves 3 per cent, of its volume of oxygen gas. Occurrence in nature: constitutes 20.93 P er cent, by volume of atmospheric air. Combined with other elements constitutes two-thirds of the entire globe, eight-ninths of all water, one- half the weight of minerals, three-quarters of the weight of animals, and four-fifths of vegetables. How made: by heating KC1O 3 and MnO 2 : 2 KC10 3 2KC1 + 3O 2 . Potassium Potassium Oxygen, chlorate. chloride. Properties: has affinity for all elements save fluorine. Is a gas, colorless, odorless, tasteless, transparent. Supports combustion and hence life. Oxidation is the term for the combina- tion of substances with oxygen. Oxidizing agents are those which part easily with their oxygen as HNO 3 , KNO 3 , KC1O 3 . Use in dentistry: a body is called "combus- tible " when it unites readily with oxygen, heat INORGANIC CHEMISTRY. 159 and light being at the same time liberated. It is the oxygen in the air which supports com- bustion, and which affords us our artificial heat and light. Substances which burn with diffi- culty in the air, owing to the latter not being pure oxygen but a mixture of oxygen with nitrogen, will burn in pure oxygen with great readiness. Oxygen blowpipes are those in which the flame is blown with a jet of oxygen; oxyhydrogen blowpipes, those where the hy- drogen burns in a stream of oxygen gas, pro- ducing a heat which fuses refractory substances such as flint, quartz, etc., and melts the various metals. Some metals, as platinum, which can not be fused in a furnace may be melted by the oxyhydrogen flame. The Atmosphere. Under the head of oxygen and nitrogen, air must be considered, which is not a com- pound, but when pure is a mixture of 20.93 parts of oxygen by volume to 79.07 of nitrogen. By weight, 23 parts of oxygen to 77 of nitrogen. In the air which we breathe are found small quantities of other substances such as watery vapor, carbon dioxide, ozone, ammonia, nitric and nitrous acids, hydrocarbons, solid particles of dust, sodium chloride, vegetable germs or spores, bacteria, etc., etc. Air in which animals are confined contains some of the organic exhalations from their bodies; in the neighbor- hood of large cities the air is contaminated by various substances like sulphuretted hydrogen poured forth from manufacturing establishments, furnaces', etc., etc. The air of cities contains more bacteria than that of the country. A cubic metre of Paris air was found to contain 160 DENTAL CHEMISTRY. 3910 bacteria, as compared with 455 in a cubic metre of country air. Hospital air has been found to contain 40,000 to 79,000 microbes to the cubic metre. TRIADS. 242. The following is a list of the most important triads: TABLE 1 8. IMPORTANT TRIADS. Bismuth } Triads positive to Gold } hydrogen. Antimony ") Triads negative to Nitrogen. J 243. Bismuth. Symbol: Bi. Latin name: Bismuth urn. Equivalence: III and V. Specific gravity : 9.78 9.80. Atomic weight: 207.5. Revised atomic weight: 207.5230. Electrical state: -\-. Fusing point: 507 F. Length of bar: 1.0014. Weight of ctibic ft. in Ibs. .-613.0. Tensile strength: 1.5. Tenacity, malleability, ductility : brittle. Conducting power (heat} : 11; ( 1 1 th rank ) . Conducting power ( electricity ) ; 1 2 ; ( 1 2th rank ). Resistance to air: tarnishes in moist air. Solubility: soluble in nitric acid; in hot sulphuric acid; in aqua regia. Direct combinations: oxygen, chlorine, bromine, iodine, sulphur. Color and appearance: white with bronze tint; highly crystalline appearance. Structure: crystallizes in rhombo- hedrons. Consistence: hard, brittle. Compounds: bismuth- ous and bismuthic. Alloys: fusible metal, pewter, pewterer's solder. Use in dentistry: for making readily fusible alloys. Occurrence: this metal occurs native, disseminated INORGANIC CHEMISTRY. 161 through rocks in veins. It is rather rare and is found as- sociated with ores of nickel, cobalt, silver, and copper. Saxony and Bohemia are the chief sources, but it is also found in Transylvania, England, United States, Sweden, Norway, and Peru. Preparation: to extract the metal the earthy matters containing it are heated and the melted bismuth is collect- ed in suitable receivers. 244. Use in dentistry: the value of bismuth in alloys is due to its low melting point, and to the fact that it expands very considerably as it solidifies. Compressed bismuth is lighter than that which has not been so treated. It is more easily vaporized than many metals and boils at moderate white heat. It tends to crystallize from fusion in a remarkable manner, in rhom- bohedrons of great size and beauty, often mis- taken for cubes. An alloy of tin, lead, and bismuth, is employ- ed for testing the finish of a die. Bismuth is used in the dental laboratory for making readily fusible alloys for dies and counter dies. It lowers the fusing point and imparts hardness when used in alloys. 245. Compounds of bismuth. - Bismuth subnitrate: official name, Bismuthi Subnitras. Formula, BiONO s .H 2 O. Molecular weight, 303.5. It is, as will be seen from the formula, the nitrate of the oxide of bismuth. It is called bismu//y/ nitrate by some authors, also bismuth trisnitrate and oxynitrate. Recent investi- gators deem it not a fixed and definite compound, but rather a mixture. The chemistry of its preparation is 162 DENTAL CHEMISTRY. complicated; bismuth is first dissolved in nitric acid, forming the nitrate; next, bismuth subcarbonate is made from the nitrate, by the action of sodium carbonate; the bismuth subcarbonate is next redissolved in nitric acid, to form bismuth nitrate again; finally, the bismuth nitrate is converted into subnitrate by action of ammonia water. Good subnitrate of bismuth is soft, bulky, insoluble in water, soluble in nitric acid. It often contains arsenic as impurity. Treatment in poisoning, as for arsenic. Used in dentistry internally and topically. 246. Alloys of bismuth.- Fusible alloys are of different compositions, but con- tain bismuth. One is bismuth 2 parts, lead I part, tin I part; melts at 200 F. Another is 50 bismuth, 12.5 cad- mium, 25 lead, 12.5 tin. VV T ood's metal, according to Essig, is bismuth 7, lead 6, and cadmium I. Fuses at 180 F. 247. Gold. Symbol: Au. Latin name: Aurum. Equivalence: I, III. Specific gravity: 19.26 to 19.34. Precipitated gold, 19.49. Atomic weight: 196.2. Revised atomic weight: 196.155. Electric state: + Fusing point: 2016 F. Length of bar: 1.0015; (8th rank). Weight of cubic ft. in Ibs.: 1208.6. Tensile strength: 9.1. Tenacity: 12; (6th rank). Malleabil- ity: i; (ist rank). Ductility i; (ist rank). Solubility: soluble in aqua regia, free nascent chlorine or bromine, mercury; unaffected by action of single acids, alkalies, or sulphuretted hydrogen. Direct combinations: chlorine, brom- ine, phosphorus, antimony, arsenic, mercury. Color and appearance: orange yellow by reflected light, very brilliant, green by transmitted light. Lustre unaffected by high temperatures. Consistence: soft. Compounds: auric and aurous. Alloys: coinage, jewelry, etc., etc. Structure: iso- metric crystals. INORGANIC CHEMISTRY. 163 248. Occurrence: gold occurs native, that is, uncombined with other metals. It is found almost everywhere, but in most regions in exceedingly small quantities. It occurs in England, Scotland, Ireland, Wales, Hungary, Transylvania, Sweden, Spain, Italy, Siberia, in the Ural Mountains, Japan, Ceylon, Borneo, Thibet, Africa, Brazil, Chili, Peru, Mexico, California, and Australia. The greatest quanti- ties are now found in Africa, California, and Australia. Gold is either in form of alluvial gold, that is, washed down by rivers, or gold- 90 copper, to 10 aluminium, as is alumin- ium bronze. Mosaic gold is a definite chemical compound, SnS 2 , stannic sulphide, made by heating in a flask at low red heat, 12 parts tin, 6 mercury, 6 ammonium chloride, and 7 flowers of sulphur; everything sublimes except the stannic sulphide which remains in the bottom of the flask. [The name " Mosaic gold " is sometimes given to substances other than stannic sulphide]. Gold base plate: different formulas are in vogue, but the constituents are in the main gold, copper, and silver; some contain platinum as well. 18 carat gold plate is made by two INORGANIC CHEMISTRY. 171 formulas: No. i contains 18 dwts. pure gold, 4 fine copper, 2 fine silver; No. 2 is 20 dwts. gold coin, 2 fine copper, 2 fine silver. Gold plate, 22 carats fine, is 22 dwts. pure gold, i dwt. fine copper, 18 grains silver, 6 grains platinum. Gold plate for clasps, wires, etc., etc.: gold used for this purpose should contain sufficient platinum to render it firmer and more elastic. A 20 carat alloy for such purposes is made by 2 formulas: No. i is 20 dwts pure gold, 2 fine copper, i fine silver, i platinum; No. 2 is 20 grains coin gold, 8 grains fine copper, 10 grains fine silver, 20 grains platinum. Gold solder is 22.2 copper, 66.6 gold, ii.i silver. 258. Compounds of Gold. Auric Chloride or the terchloride of gold, AuCl 3 . Pre- pared by dissolving gold in aqua regia, using gentle heat. The solution evaporated to dryness, over the water bath, yields ruby-red, prismatic crystals, deliquescent, soluble in water, alcohol, ether, and of disagreeable, styptic taste; auric chloride stains the skin purple, but the stain is readily removed by potassium cyanide. It is an escharo- tic and disinfectant, and dissolved in ether is used in dentistry as an obtunding agent. Solutions should be kept in glass stoppered bottles, as the gold tends to deposit from solutions. It is a poison. Auric Oxide, Au 2 O 3 , is prepared from the terchloride by digesting magnesia in it, by which magnesium aurate is formed. The lat- ter is decomposed by nitric acid and the residue 172 DENTAL CHEMISTRY. auric oxide, when dried, is a dark brown, easily decomposing; powder. Purple of Cassius is a compound of gold, tin, and oxygen. It may be prepared by treating gold chloride with solution of stannous chloride, or by adding stannous chloride to a mixture of stannic chlor- ide and auric chloride, as follows: 7 parts of gold are dissolved in aqua regia, and mixed with 2 parts of tin also dissolved in aqua regia; this solution is largely diluted with water, and a weak solution of i part tin in hydrochloric acid is added drop by drop, till a fine purple color is produced. The purple of Cassius re- mains suspended in water, but subsides gradu- ally, especially if some saline substance be added. Purple of Cassius is a brown, reddish purple or black powder soluble in ammonia. It is used as a coloring for porcelain. Its composition is doubtful, probably Au 2 O.SnO 2 . SnOSnO 2 .4H 2 O., that is a double stannate of aurous oxide and stannous oxide. 259. Antimony. Symbol: Sb. Latin name : Stibium. Equivalence ; III and V. Specific gravity : 6.72. Atomic weight: 120. Re- vised atomic weight : 119.955. Electrical state : . Fusing point: 842 F. Length of bar: i.ooii; (nth in rank). Weight of cubic feet in Ibs : 419.5. Tensile strength: 0.5. Tenacity, malleability, ductility : brittle. Conducting power (heat}: 10; (loth rank). Conducting power (electricity) ; 46; (silver = 1000); (iithrank). Resistance to air, etc : takes INORGANIC CHEMISTRY. 173 fire at red heat, but scarcely tarnishes in air. Solubility : in boiling hydrochloric acid to which a little nitric has been added: in fine powder, dissolved by solutions of higher sulphides of Na and K. Direct combinations : with chlorine, sulphur, oxygen, bromine, iodine. Color and ap- pearance: brilliant bluish-white, like zinc. Structure: rhombohedral crystals like arsenic and red phosphorus; there is also an amorphous form. Consistence ; hard, brittle. Compounds : antimonous (III) and antimonic (V). Alloys ; Britannia metal, pewter, type metal, Babbitt's anti-friction metal. Occurrence: antimony is found both native and com- bined. It occurs free in Germany. Gray antimony ore, the sulphide, Sb.^Ss, occurs in England, France, Hungary, and Borneo. An oxide is found in Algeria. Red antimony, which is a compound of the oxide and sulphide is found in Tuscany. Antimony is also found in the United States and in Mexico. Preparation; the principal ore (stibnite), which is a sul- phide, yields regulus of antimony (metallic antimony) when melted with metallic iron. A purer article is ob- tained by roasting the crushed ore, converting it into an oxide; the latter is then fused with charcoal. Properties: the metal is not attacked by hydrochloric acid. Nitric acid converts it into a white, insoluble oxide. Aqua regia dissolves it, forming a chloride called " but- ter of antimony"; water converts this chloride into an oxychloride. SbCl.3 + H 2 O = SbOCl + 2HC1. Autimonous Water. Antimony Hydrochloric chloride. oxychloride. acid. This equation illustrates the formation of an oxychlor- ide. 260. Uses in dentistry and the arts: antimony is valu- able as a constituent of alloys: to give hardness to other 174 DENTAL CHEMISTRY. metals, and to cause them to expand and completely fill moulds on cooling. It can be distinguished from other metals by its brittle- ness, crystalline structure, and hardness; it can easily be pulverized, and breaks from a slight tap of a hammer. It is not deemed a metal by some, being classed with arsenic and phosphorus, rather than with the metals. It burns at red heat, with dor of garlic and with white fumes, suggesting arsenic. The amalgam with mercury is soft and decomposed by contact with air or water, antimony separating. It has been used in dental amalgam alloys. 261. Boron. Symbol: B. Latin name: Boron. Equivalence: III. Specific gravity : 2.63. Atomic wt, ( approx. ) : 10.9. Atomic wt. (revised}; 10.941. Electrical state: . Properties: amorphous, greenish powder, soluble in melted aluminium. Boron is not used in dentistry. 262. Hydrogen Orthoborate or Boracic Acid. Synonyms: boric acid, orthoboric acid, sedative salt of Homberg. Official name, Acidum Boricum. Theoretical' constitution: orthoboric acid, H 3 BO 3 , graphically, B"' (HO) 3 . Composed of three atoms of hydrogen, one of boron, and three of oxygen. By weight, 3 parts of hydrogen, n of boron, and 48 of oxygen. Molecular weight, 62. Preparation: boracic acid is made from borax by add- ing hydrochloric acid to a hot solution of the former, which causes a precipitate of boracic acid: Na 2 B 4 O 7 + 2HC1 + 5H 2 O = 4H 3 BO 3 + 2NaCl. Borax. Hydrochloric Water. Boric acid. Common acid. salt. Properties: brilliant, white, shining, odorless, six-sided plates, greasy to the touch, slightly soluble in cold water i part in 25, soluble in 3 parts hot water, soluble in 6 parts alcohol, soluble in glycerine. Specific gravity, 1.517 at ordinary temperatures. Is a powerful antiseptic. Satu- INORGANIC CHEMISTRY. 176 rated with alcohol, burns with a green flame. Its solu- tions are but faintly acid; turmeric paper moistened with a solution of this acid becomes reddish-brown on drying. Heated with glycerine forms boroglyccnde. (See Boro- glyceride under head of Glycerine). Use in dentistry: boracic acid is used for various antiseptic purposes. Combined with sodium sulphite it has been used as a bleaching agent for discolored teeth. (See Boroglycer- ide). 263. Arsenic. Metallic arsenic is not used in medicine or dentistry. One of its compounds, arsenous oxide or anhydride, is of im- portance, and the term arsenic is usually applied to this substance. Arsenous Anhydride. Synonyms: arsenious acid, arsenious anhy- dride, white arsenic, ratsbane, white oxide of arsenic, Arseniosum Oxidum. Official name, Acidum Arsenosum. Theoretical constitution: As 2 O 3 , arsenous oxide, two atoms of arsenic to three of oxygen, by weight 150 of arsenic to 48 of oxygen. Molecular weight, 198. Composed of 75.76 per cent. As and 24.24 per cent. O. [The molecule of vitreous arsenic is thought to be represented by the formula As 4 O 6 ]. Preparation: arsenous oxide occurs in nature as arsenic " bloom," a term derived from the Saxon bloma, a lump. It is obtained by roast- ing ores of other metals containing it in a cur- 176 DENTAL CHEMISTRY rent of air. The arsenous oxide in the roast- ing process volatilizes and is condensed in suitable receiving chambers as a white powder. Properties: it is found in the form of a fine, white, heavy powder or in glassy looking lumps. The powder is somewhat gritty, odor- less, tasteless, permanent in air. Condensed from sublimation at 752 F., it is a transparent, vitreous mass, sp. gr., 3.738. When condensed at temperature slightly less, crystallizes in right rhombic prisms. Vitreous arsenic, on keeping, gradually becomes opaque and crystalline. When condensed at 392 P., it occurs in octahedral crystals, sp. gr., 3.69. This form is also obtained on evaporating a satu- rated aqueous solution. Vitreous arsenic is slightly more soluble than the opaque; 100 parts boiling water dissolve 12 parts of the vitreous; on cooling, about three parts are left in solution. Arsenic is soluble in hot HC1, in solutions of alkalies and of tartaric acid. Dissolved in acids it forms a binary compound of arsenic, as, for example, arsenous chloride when dissolved in hydrochloric acid. Dissolv- ed in alkalies it acts as the negative element forming arsenites of the alkali metals, as K 2 HAsO 3 , potassium hydro-arsenite. Locally, it acts as an escharotic, first des- troying the vitality of organic structure, de- composition then ensuing. INORGANIC CHEMISTRY. 177 It is a powerful antiseptic, retarding" putre- faction to a marked degree. Uses in dentistry: arsenous oxide is used to destroy the vitality of tooth pulps; it has also been used as an obtunding agent. It kills a tooth by causing irritation; there is increased flow of blood to the parts, the arteries are en- larged so that there is no return of blood through the veins, hence strangulation at apex of the tooth. Toxicology: arsenic in doses of from one to two grains is a powerful poison. It is poison- ous also even when locally applied. There is danger of absorption when arsenic is applied to the teeth. The treatment of poisoning" by this agent, when administered internally, is to provoke or promote vomiting by giving large quantities of hot milk and water or emetics, as sulphate of zinc (5 grains repeated in 15 minutes) or must- ard (teaspoonful or two of ground mustard in water); subcutaneous injection of apomorphine hydrochlorate in doses of i to i of a grain will speedily bring about emesis. The antidote to arsenic is ferric hydrate, conveniently made by adding Aqua Ammonias to Tincture of Ferric Chloride. A brownish substance is formed which, separated from the liquid, may be given ad lib. The antidote should be given after vomiting has been brought about. Finally 178 DENTAL CHEMISTRY. bland liquids, such as milk and eggs, should be given; sugar and magnesia in milk are highly recommended. When arsenic has been ab- sorbed from local application it is of course useless to give emetics, etc., the only treatment possible being that of treating the symptoms as they appear, promoting elimination by diur- etics as potassium nitrate, etc., etc. Note: in making the antidote for arsenic let the precipitate drain on a wetted muslin strainer until most of the liquid has run off, gather up the cloth, press it with the hands until no more liquid can be squeezed out, then add \vater and administer. The official hydrate is made from solution of normal ferric sul- phate. 264. Phosphorus. Symbol: P. Atoms in molecule: P 4 . Atomic weight: 31. Molecular weight: 124. Density, of vapor: 62. Specific gravity: yellow 1.83, red 2.14. How liquefied: the yellow melts at m F. under water. Solubility: yellow is insolu- ble in both water and alcohol, but soluble in carbon disulphide, while the red is insoluble in the latter. Occurrence in nature : does not occur native, but as phosphates, etc. How made: from ash of burnt bones by treating with sulphuric acid, and heating with charcoal. Properties: yellow is translucent, waxy, shines in the dark, readily oxidized, taking fire at 140 F. and must be kept under water. Becomes covered with red or white coat on exposure to light; poisonous. Red does not in- flame readily, and is not poisonous. Phosphorus com- INORGANIC CHEMISTRY. 179 bines with most elements except C, N, and, H, and redu- ces some metallic salts as of Cu, Ag. Use in dentistry : phosphorus is of value as a deoxi- dizer in fusing refractory metals such as iridium, nickel, etc. Toxicology. Carious teeth, swollen and in- flamed gums, finally necrosis of the jaws, usually of the lower one, are often noticed in those who work in match factories. Most cases of phosphor-necrosis originate in un- sound teeth or where the gums are kept away from the teeth by tartar. About 7 Uh grain of phosphorus is contained in a match head. In the dipping and packing room the matches are handled the most, and in damp weather the fumes are given off so that no workman with carious teeth should work in these rooms. Alkaline mouth-washes should be used, and workmen should keep their hands clean and not eat in the work rooms. Good ventilation should be secured. The use of red phosphorus instead of .yel- low is to be advised, as the former is not poisonous. 265. Anhydrous Phosphoric Acid, so called, is phos- phoric anhydride, i. e., phosphoric oxide or phosphorus pentoxide, P 2 O 6 , and is formed by the rapid burning of phosphorus in air or in oxygen. It is very deliquescent. It forms with water a solution of the glacial acid, HPO 3 . P 2 O 5 + H 2 =* H 2 P,O. = (HPO 3 ) 2 or 2HPO 3 . Phosphoric water. Glacial phosphoric acid, anhydride. 180 DENTAL CHEMISTRY. 266. Hydrogen Phosphate or Phosphoric Acid.- There are several kinds of phosphoric acid, but we shall here speak of two only: i. Common Phosphoric Acid. * Synonyms: tri-basic phosphoric acid, tri- hydrogen phosphate; (it is sometimes called ortho-phosphoric acid). Theoretical constitution: H 3 PO 4 : may be regarded as mono-meta-phosphoric acid, i. e., the acid obtained by removing- one molecule of water from ortho-phosphoric* acid, Ortho- phosphoric acid has for its formula H 5 PO 5 , which formula minus H 2 O becomes H 3 PO 4 , rationally (PO)'"(HO) 3 . The acid contains, then, three atoms of hydrogen, one of phos- phorus, and four of oxygen; by weight 3 parts hydrogen, 31 of phosphorus, 64 of oxygen. Molecular weight, 98. Its salts are phos- phates?* Preparation: made by boiling phosphorus in dilute nitric acid, and evaporating to a syrupy liquid. Properties: syrupy liquid, which, if evap- * Phosphoric acid is tri-basic, and, therefore, three hydroxyl groups are assumed to be present in it, hence the rational formula is PO (HO)s. The graphic formula is probably /OH POc- OH \OH ** Called often ortho-phosphates. INORGANIC CHEMISTRY. 181 orated spontaneously over sulphuric acid, gives hard, transparent, prismatic crystals readily deliquescing. It does not coagulate albumin. Acidum Phosphoricum, U. S. P., is a color- less, strongly acid liquid of sp. gr. 1.347. It does not fume and should not contain arsenic. It contains 50 per cent, acid to 50 of water. It is odorless. Acidum Phosphoricum Dilutum, U. S. P., contains 10 per cent, of H 3 PO 4 , and is com- posed of i part of Acidum Phosphoricum, to 4 of distilled water. Symtpy phosphoric acid: H 3 PO 4 , syrupy phos- phoric acid, contains on an average, about 66 per cent, of H 3 PO 4 , and as sold by manufac- turing chemists is not the glacial acid but merely a strong phosphoric acid of syrupy consistence. It is of different strengths ac- cording to the makers. 2. Glacial Phosphoric Acid. Synonyms: mono-hydrogen phosphate, meta-phosphoric acid, di-meta-phosphoric acid, mono-hydrated phosphoric acid. Theoretical constitution: HPO 3 or di-meta- phosphoric acid, i. e., derived by subtracting two molecules of water from ortho-phosphoric* acid. H.PO. 2H a O HPO.. Its molecule, therefore, consists of i part hydrogen, i part * Not what is usually called ortho-phosphoric acid, but the maxi- mum hydroxide or normal acid of phosphorus. 182 DENTAL CHEMISTRY. phosphorus, and 3 parts oxygen; by weight I part hydrogen, 31 of phosphorus, and 48 of oxygen. Molecular weight, 80. Preparation: it may be made by heating the ordinary acid, which loses a molecule of water and becomes the glacial acid. H 3 PO 4 HP0 3 + H 2 Phosphoric acid. Glacial phosphoric acid. Water. It is sometimes made by calcining ammo- nium phosphate, but the product is then likely to contain ammonia.* Properties: on cooling the platinum vessel in which the common acid, H 3 PO 4 , has been heated to redness, a vitreous mass, HPO 3 , is seen, hard, colorless, transparent, not crystalli- zable, readily soluble in water, forming an in- tensely acid solution which is slowly converted into the ordinary acid. It coagulates albumin. In commerce it comes in the form of sticks or brittle cakes, odorless, sour to the taste and hygroscopic, more or less contaminated with pyro-phosphoric acid, and containing phos- phates of sodium, calcium, magnesium, etc. Solution of the common acid in water when heated becomes first pyro-phosphoric acid, then (at red heat) glacial phosphoric acid. Use in dentistry: the dilute acid is used as * The formation of meta-phosphoric acid from ordinary phosphoric acid is represented thus: ( f O i nw I u ^ = p 1 Q + H 2 O J ^ P J 1 OH - P j 1 OH OH INORGANIC CHEMISTRY. 183 a local application in caries, and has been given internally. It is liable to fungoid growth of a tenacious or mucoid character, diffusible, and of a yellowish-gray color; it loses strength on development of this growth, its specific gravity falling often below 1055. TABLE 22 PHOSPHORIC ACIDS. COMMON PHOSPHORIC ACID. H 3 PO 4 . Called by some ortho-phos- phoric acid. Syrupy liquid. Evaporated spontane- ously yields pris- matic crystals. Does not coagulate albumin. Strong acid is called syrupy phosphoric acid. The official acid (50 per cent.) heated above 392 F. is con- verted gradually into the glacial acid and pyrophosphoricacid. Little or no precipitate with solution of sil- ver nitrate. * Rollins obtains it as a soft solidby the process given in section 201. It is said {Zeitschrift f. anal. Cliemie., VI. 187,) that really pure phos- phoric acid makes a soft glutinous mass when heated, but on heating strongly for seven or eight minutes after the acid has begun to go off in white fumes a hard mass is obtained. GLACIAL PHOSPHORIC ACID. HPO 3 . Called meta- phosphoric acid. Solid. Does not crystallize, but forms an amor- phous, glassy mass, coagulates albumin. Slowly turns into the common acid. Is volatile at red heat, and when boiled with water is con- verted into the com- mon acid. Abundant precipitate with solution of sil- ver nitrate. 184 DEXTAL CHEMISTRY. 267. Nitrogen. Symbol: N. Atoms in molecule: N 2 . Atomic weight: 14. Molecular weight: 28. Density: 14. Specific gravity: 0.971, (air=i). Weight of one litre of gas: 1.256 grammes. Solubility in water: I part of water dissolves 0.025 part by volume of nitrogen. Occurrence in nature: nitrogen constitutes 79.07 per cent, by volume of atmospheric air. How made: obtained from air by burning phosphorus in a confined space. Properties: affinity for magnesium, borum, vanadium, titanium. Very inert chemically. Colorless, tasteless, odorless, transparent gas. Incombustible and does not support combustion. In combination found in nitro- glycerine, poisonous alkaloids as strychnine, and in albu- minoid substances. 268. Ammonia. Theoretical constitution: H 3 N or NH 3 , one atom of nitrogen to three of hydrogen; by weight, 14 parts nitro- gen to 3 of hydrogen. Molecular weight, 17; density, 8.5; specific gravity, 0.59 (air = i). Origin and method of preparation: it is a product of the putrefaction of animal matters. Artificially it may be prepared by heating sal-ammoniac and quicklime. Properties: colorless gas, pungent odor, strongly alka- line, extraordinarily soluble in water, 1149 volumes of the gas in i of water. Very volatile. 269. Mtrogen Monoxide or Laughing Gas. Synonyms: hyponitrous oxide, nitrous oxide, nitrogen protoxide. Discovered by Priestly in 1776; first came into notice as anaesthetic in 1863; first used in dentistry by Wells of Hartford, in 1845. Theoretical constitution: N 2 O, hyponitrous INORGANIC CHEMISTRY. 185 oxide or nitrogen monoxide; univalent nitro- gen with bivalent oxygen two atoms of nitro- gen with one of oxygen; composition by vol- ume, 2 parts of nitrogen to I of oxygen; by weight, 28 parts of nitrogen to 16 of oxygen. Molecular weight, 44. Density, 22. Sp. gr., 1.527. Weight of a litre, 1.98 gramme. Preparation: made by ca^ltio^lsly heating ammonium nitrate, which is decomposed, yielding laughing gas and water: NH 4 NOs N 2 O + 2 H 2 O Ammonium nitrate. Nitrogen protoxide. Water. Properties: colorless, odorless, sweetish- tasting gas of neutral reaction, soluble in water 100 volumes of which dissolve 78 vol- umes of the gas, more soluble in alcohol. Supports combustion, the heat of burning bodies decomposing it and setting oxygen free. Condenses to a colorless liquid under pressure of 50 atmospheres and temperature of 45F., specific gravity of the liquid, 0.908. Boiling point, i26F., freezing point, i5oF. When inhaled it causes exhilaration, anaes- thesia, and finally asphyxia. It dissolves in the blood without entering into combination with it, and its action seems to be due partly to its excluding air and partly to its direct effect on the nervous system. The anaesthesia produced by it is of short duration and with- out an excitement stage. The sensation is 186 DENTAL CHEMISTRY. usually one of agreeable intoxication; dis- agreeable after-effects are generally wanting. Lyman holds that the anaesthesia is a narcosis, but Wallian thinks with Ziegler that it is not merely an asphyxiating agent. Use in dentistry: as a temporary anaesthetic. Out of 121, 709 administrations of the gas re- corded from 1863 to 1 88 1, there was not one which resulted fatally, nor produced serious ill-effects. For anaesthetic purposes the nitrogen mon- oxide is liquefied and sold in wrought-iron cylinders provided with a stop-cock, on turn- ing which the liquid is vaporized, and may be collected in rubber gas bags or small gasome- ters. When the gas is to be administered it may be inhaled from the gas bag or gaso- meter through a rubber tube and mouth-piece provided for the purpose. The advantages of the cylinder are that the gas may be kept for any length of time without loss of strength or volume. 270. Hydrogen Nitrate or Nitric Acid.- Synonyms: hydric nitrate, Glauber's spirits of nitre, spirits of nitre, fuming spirits of nitre, aqua fortis, azotic acid. Official name, Acid- um Nitricum. Known to the Arabs in the Qth century. Theoretical constitution: HNO 3 , an ox-acid whose molecule is composed of i atom of hy- INORGANIC CHEMISTRY. 187 drogen, i of nitrogen, and 3 of oxygen. By volume it consists of i part of hydrogen, i of nitrogen, and 3 of oxygen. By weight, i part of hydrogen, 14 of nitrogen, 48 of oxygen. Molecular weight, 63. Preparation: made by decomposing 1 potas- sium nitrate (nitre) with sulphuric acid: KNOs + H 2 S0 4 KHSO 4 + HNO 3 Potassium Sulphuric Potassium acid Nitric nitrate. acid. sulphate. acid. Properties: the pure acid is a colorless, fum- ing, corrosive, rather heavy, strongly acid liquid of sp. gr. 1.52. The official acid has a specific gravity of 1.42, and contains 69.40 per cent, of absolute acid to 30.60 per cent, of water. Exposed to air and light it is decom- posed and becomes yellow. Nitric acid dis- solves mercury, copper, silver, and bismuth, especially when warmed; dilute nitric acid dis- solves iron, lead, and silver. Antimony and tin are attacked by the acid and oxidized, but not dissolved. Nitric acid has no action on gold, platinum, or iridium. It attacks and destroys vegetable and animal tissues, pro- ducing a yellow discoloration, especially on animal matters and products. Its stain on clothing can not readily be removed but ammonia prevents destruction of the cloth. Its salts are nitrates. Acidwn Nitricittn Dilutum is one part of the official acid to six of distilled water. Its 188 DENTAL CHEMISTRY. sp. gr. is 1.059, an d it contains ten per cent, of HNO 3 . Use in dentistry: mixed with four parts of hydrochloric acid, it is used to dissolve gold. [The official mixture is four parts nitric acid by weight, to 15 of hydrochloric acid, and is called Acidum Nitrohydrochloricum]. Nitric acid is also used to dissolve zinc oxide in the preparation of the oxyphosphate cement. It is used in dental medicine as a caustic. It attacks the teeth, and hence, when used in any form in the mouth, care should be taken that it does not touch other tissues than the ones to which it is applied. Toxicology: nitric acid is a violent poison turning the mucous membranes a bright yel- low and then corroding them. The antidotes are alkalies or magnesia suspended in water, sodium bicarbonate in water, soap and water; bland liquids should be given and the patient's strength sustained. Burns should be treated like those from hydrochloric acid. (See section 181). INORGANIC CHEMISTRY. 189 TETRADS. 271. The following is a list of important tetrads: TABLE 23. TETRADS. Aluminium.* ) Cerium.* Tetrads Tin. i positive Palladium. I to Platinum. hydrogen. Iridium. C ;i- 1 Tetrads TitanTum. 4g*e Carbon ' J hydrogen. 272. Aluminium. Symbol; Al. Latin name: Aluminium or Aluminum. Equivalence: IV and (A1 2 ) VI . Specific gravity: 2.50 to 2.67. Atomic weight: 27. Revised atomic weight: 27.009. Electri- cal state: +. Fusing point: I292F. Length of bar: etc.: 1.0022 (5th rank). Wt. of cubic ft. in Ibs.: 166.8. Tensile strength; 12. Tenacity: like silver. Malleability: like silver and gold. Ductility: 7; (7th rank). Conducting power (heat}: 4; (4th rank). Conducting power (electricity}: better than that of iron. Resistance to air, etc.: tarnishes very slowly; not affected by sulphuretted hydrogen. Solubility: solu- ble in hydrochloric acid, and in aqueous solutions of alkaline hydrates; resists cold acids, mineral and vegeta- ble (except hydrochloric). Direct combinations: with many metals and non-metals. Does not oxidize; is not attacked by sulphur compounds. Color and appearance: bluish white, brilliant. Structure : octahedral crystals. Consistence: hard as zinc. Very sonorous. Compounds: * Both aluminium and cerium appear to be trivalent, but are really' quadrivalent like the ferric compounds. 190 DENTAL CHEMISTRY. two atoms with equivalence of six like ferric salts. Alloys; aluminium bronze, solder, etc. Does not amalgamate. Use in dentistry: for making " plates." Occurrence: the great mass of the earth is composed of aluminium, in combination with silicic acid, in silicated rocks, such as granite, feldspar, basalt, slate, mica, etc., and in the various modifications of clay. Every variety of clay contains it in quantity varying from 12 to 20 per cent.* The minerals known as corundum, ruby, sapphire, and emery are aluminium oxide in crystallized state. Preparation: the usual process for obtaining aluminium has been to decompose the chloride by metallic sodium: A1 2 C1, + 6Na = 6NaCl + 2A1 It will be noticed that aluminium acts as a pseudo-triad, (A1 2 ) VI , in the chloride of aluminium. The process is that of Deville. At the works of Morin in Paris, ten parts sodio-aluminium chloride, five parts of fluorspar or cryolite, and two parts of sodium, are mixed together and thrown upon the hearth of a reverberatory furnace, previously heated to full redness. A violent action takes place, great heat is evolved, and the lique- fied mass of slag and metal collects at the back of the furnace. The latter is drawn off and cast into ingots. Metallic sodium is very troublesome to handle, and its cost has been so high that the price of aluminium has been, in consequence of the difficulty and expense of the process, higher per troy ounce than that of silver. Re- cent improvements in process have been made in this country; one is to reduce the aluminous materials with sodium vapor, and to use the double fluoride of aluminium and sodium, or double chloride of aluminium and sodi- um, made at reduced cost; another is to prepare the * The sapphire and ruby contain also a little oxide of iron ; emery contains oxide of iron and also silica. INORGANIC CHEMISTRY. 191 metal electrolytically;* another to reduce the aluminous earths with zinc ore. The price will probably be greatly reduced before long. Metallic magnesium has been re- duced to one-fifth of its previous price, and, as this sub- stance also is used in manufacture of aluminium, it will, probably, affect the price o'f the latter.f 273. Value in dentistry and in the arts:J aluminium is remarkable for its resistance to the air, and for its great lightness. It is said to be stronger than steel. It is four times lighter than silver, and seven or eight times lighter than platinum. Gas fumes and sulphur do not tarnish it. It iswhiterthan nickel, and makes a fine substitute forsilver. Alloyed with silver and copper, it gives a non-tarnishing and non-corrosive quality to these metals, and greatly in- creases their tensile strength. Aluminium bronze is com- posed of 10 pounds of aluminium to 90 pounds of copper, and has a tensile strength of three tons per square inch greater than Bessemer steel. A solder has been invented which, it is claimed, will enable aluminium to be welded. [An alloy of aluminium and tin has been used, 10 parts tin to 100 of aluminium, for internal parts of instruments, as electrical instruments. The apex of the Washington Monument is of aluminium; its surface appears much whiter than silver, and is so highly polished as to resem- ble a plate glass mirror]. * The Cowles method consists in passing a powerful electric current through a mixture of mineral copper and carbon. A high temperature is obtained by which the mineral is reduced by the carbon. f The Netto process involves the use of ingots of sodium. J When aluminium is to be melted to make a casting, for instance, this must not be done in clay crucibles, since it reduces the silica contained therein to silicium, whereby it becomes gray and brittle. It must be melted in lime crucibles ; or if clay crucibles are used, they must be lined with carbon or well-ignited cryolite. Graphite crucibles, however, are the best. 192 DENTAL CHEMISTRY. In prosthetic dentistry the use of aluminium has been urged, on the ground (i) that it is the only metal which can be usedfatre and unalloyed in the manufacture of plates, (2) that it is the lightest of the metals available for such a purpose. It is claimed by some that aluminium is unalterable in the mouth, and does not irritate the gums, hence is superior to caoutchouc. It is thought, therefore, that it will replace gold and platinum in prosthetic dentistry.* According to Palmer there is little or no galvanic action in the oral cavity when aluminium is used; a carpet tack may be held in the mouth, in contact with the aluminium, without unpleasant sensation. 274. Alloys of Aluminium. Aluminium solder is 6 parts aluminium, 4 copper, 90 zinc. Others have been devised as follows: No. l. No. 2. No. 3. Zinc .... 80 85 88 Copper 8 6 5 Aluminium. ... .... 12 9 7 * Some have claimed that it is gradually attacked by articles used in diet, such as vinegar and solutions of common salt, and by alka- line solutions. Chandler's objection to its use is the difference in expansion between it and the vulcanite used in fastening the teeth. The heat of the mouth, hot drinks, etc., etc., cause a separation. Carbonate of lime is deposited from the saliva in the opening, until finally the space is perceptible to the tongue. INORGANIC CHEMISTRY. 193 Aluminium may be soldered by coating it with copper as in electrotyping, then soldering as usual.* 275. Compounds of Aluminium. Alums : Theoretical constitution: alums are what are known as "double salts." They are formed by the combination of aluminium sulphate with other sulphates. The formula for aluminium sulphate is (A1 2 ) 2 (SO 4 ) 6 or A1 8 (SO 4 ) 3 , alum- inium being a pseudo-triad. The formula for potas- sium sulphate is K 2 SO 4 , for ammonium sulphate (NH 4 ) 2 SO 4 . The formula for potash alum or potassium and aluminium sulphate is K 2 A1 2 (SO 4 ) 4 , that is K 2 (SO 4 ) + A1 2 (SO 4 ) 3 . Ammonia alum is (NH 4 ) 2 A1 2 (SO 4 ) 4 24H 2 O. Ferric alum contains no aluminium at all, but is the double sulphate of ammonium and ferric iron, thus (NH 4 ) 2 Fe 2 (SO 4 ) 4 .24H 2 O. The official alum is potash-alum, K 2 A1 2 (S0 4 ) 4 .2 4 H 2 0. Official name: Aluminii et Potassii Sulphas. Preparation and properties: alum is manufactured, on a large scale, by decomposing various silicates of alumin- ium with sulphuric acid, aluminium sulphate being formed. To this is added solution of potassium sul- phate, if potash alum be desired, or ammonium sulphate, if ammonia alum is sought. On evaporation the alum crystallizes. Potash alum occurs in form of regular octahedral crystals, white, efflorescent, soluble in 10 parts of cold water and * A good solder for aluminium is said to be made by melting to- gether 5 parts of zinc, 2 parts of tin, and 1 part of leadf and rolling this out into thin sheets. The aluminium surface to be soldered must be scraped clear of all oxide, and coated with paraffin. A piece of the solder is then placed upon each portion and heated This causes the paraffin to melt ; on further heating the solder melts and unites with the aluminium. The two surfaces thus coated are then soldered together in the usual manner. 194 DENTAL CHEMISTRY. 0.3 parts boiling, insoluble in alcohol; its solution has an acid reaction and an astringent, sweetish taste. By heating for several days at a temperature of I76F., the water of crystallization is expelled and it becomes dried alum, Alumen exsiccatum. Alum is used in dentistry as an astringent, styptic, and, in connection with Labar- raque's solution, as a bleaching agent. Aluminium chloride: this substance, A1 2 C1 6) comes in colorless, deliquescent crystals, very soluble in water, of a sharp saline taste, antiseptic, disinfectant. It is made by passing chlorine gas over a mixture of charcoal and alumina at bright red heat: A1 2 3 + 3C + 6C1 == 3 CO + ALC1 6 Alumina carbon chlorine carbon aluminium monoxide chloride It has been used to bleach discolored teeth. The substance called Choralwn contains the chloride of aluminium. Aluminium permanganate: this substance is said to be a constituent of some disinfecting solutions. Aluminium silicates: there are many silicates of alu- minium. Clay is a hydrated silicate, usually mixed with excess of silica. Purer kinds of clay are derived from feldspar of the formula, Al2O 3 K 2 0, 6SiO 2 . On exposure to air the silicate of aluminium alone remains, the alka- line silicates washing away. Earthenware, bricks, and pottery are made from clay, porcelain and the better kinds of stoneware from the purest clay, and glazed with feld- spar. Firebricks, crucibles, and the like are prepared from pure varieties of clay, free from lime, magnesia, or iron, but containing a large proportion of silica. Com- mon clays have the formula, Al 2 O 3 .2SiO 2 ; some kinds of fire clay, Al 2 O 3 .6SiO 2 . Silicate of aluminium is an ingre- dient of hydraulic cement. Alumina is an oxide, A1 2 O 3 . Corundum and emery are nearly pure alumina. INORGANIC CHEMISTRY. 195 276. Artificial teeth: teeth are composed of two portions, the body or base and the enamel. The constituents of the body are chiefly silex, feldspar, and kaolin. The en- amel is composed principally of feldspar. Coloring 1 matters are also used, and consist of various metals, in a state of minute division, or of metallic oxides. 277. Feldspar is a double silicate of alumin- ium and potassium, its composition being represented by the formula, K 2 Si 3 O 7 , Al 2 Si 3 O 9 . It also contains lime and oxide of iron. It is prepared for dental uses in the same way as silex. It is readily fusible. 278. Kaolin is essentially a silicate of alu- minium. It usually contains oxide of iron and some other substances, as magnesia, potash, etc., etc. It is the result of the decomposition of feldspar. Relatively large proportions of kaolin give teeth an opaque and lifeless ap- pearance; modern mineral teeth contain less kaolin and more feldspar. It is prepared for dental .uses by washing, letting settle, decant- ing, letting settle, decanting again, and drying in the sun. 279. Crown enamels are composed of feld- spar, as a basis, with various coloring matters, such as titanium, spongy platinum, oxide of gold. 280. The dry method of preparation of 196 DENTAL CHEMISTRY. gum-enamel as practised by Wildman and described by Essig, is divided into three stages : first, the preparation of the oxide ; second, fritting, or, by aid of heat, uniting the metallic oxide with a silicious base; and, third, diluting the frit so as to form the desired shade. In this method the purple of Cassius (metallic oxide) is prepared in the dry way by fusing silver, gold, and tin with borax, removing borax glass formed, dissolving the silver with nitric acid, washing well and drying. The frit is formed by mixing the purple of Cassius thus made with a flux composed of quartz, borax glass, and sal tartar. Lastly, the frit is diluted with the proper amount of feldspar. 281. Cerium. Symbol: Ce. Latin name: Cerium. Equivalence: II and IV. Specific gravity: 6.62. Atomic weight (approx. ): 140.4. Atomic weight ( revised): 140.424. Electrical state: +. The most important compound is the oxalate. (Sec- tion 435). 282. Tin- Symbol: Sn. Latin name'. Stannum. Equivalence: II and IV. Specific gravity: 7.29 to 7.30. Atomic weight: 117.7. Revised weight: 117.698. Electrical state: -f-. Fus- ing point: 442F. (According to some, 458.6F.) Length of bar at 21 2: 1.0023; (4 th rank). Weight of cubic feet in Ibs.: 455.1. Tensile strength: 2 to 3.5. Tenacity: 1.33 com- pared with lead; (gth rank). Malleability: 4; (4th rank). Ductility: 9; (gth rank). Conducting power (heat}: 7; (7th rank). Conducting power (electricity}: 83, (silver = 1000); (9th rank). Resistance to air, etc.: 3; (3d rank). Solu- INORGANIC CHEMISTRY. 197 bility. soluble in dilute acids and alkalies. Resists cor- rosion of air, water, etc., better than iron or copper. Nitric acid converts it into metastannic acid. Dissolved in hydrochloric acid, stannous chloride is formed. In aqua regia, stannic chloride. Direct combinations: with oxygen when strongly heated, sulphur, chlorine. It does not combine chemically with mercury. Color and appear- ance', white, brilliant. Structure', crystalline in two sys- tems, isometric and quadratic. Consistence: soft. Com- pounds: stannic (equivalence IV) and stannous (equiva- lence II). Alloys: pewter, brittania, queen's metal, solder, bell-metal, gun-metal, bronze, speculum metal, fusible metals, sterro-metal, type metal. Occurrence: tin occurs chiefly in form of tinstone, stannic oxide, SnO 2 . The ore is found in Cornwall, Australia, Bohemia, Sax- ony, Malacca, Banca, Siberia, Sweden, North and South America. Tin obtained from Ma- lacca and Banca is known as straits tin, and is of great purity: The tin deposits of New South Wales cover an area of over 5,000,000 acres; tin ore is also very abundant in Queens- land. In the United States tin ore has been found in West Virginia and adjoining parts of Ohio, in North Carolina, and in the far West, as in Utah, Dakota. Preparation: the metal is easily obtained from the ore by heating the latter, after purifi- cation, with coal: 2SnO 2 + 2C 2 = Sn 2 + 4CO Stannic Carbon Tin Carbon oxide mon-oxide 283. Pure tin, in crystalline form, may be 198 DENTAL CHEMISTRY. thrown down by introducing a plate of tin into a strong; solution of stannous chloride, on which water is floated. Another method by which tin, entirely pure, may be obtained is by evap- orating a solution of stannous chloride to small bulk, and oxidizing- by addition of nitric acid. Stannic oxide is obtained, which, after washing and drying, is exposed to a red heat in a crucible with charcoal. 284. Tin in dentistry: tin amalgamates readily with mercury, and in most cases there is condensation. Pure tin in form of foil is used as a filling, and also in connection with non-cohesive gold. 285. Alloys of tin.- Pewter is an alloy of variable composition, usually tin, lead, copper, and antimony or zinc. Plated pewter is 7 antimony, 2 bismuth, 2 copper, 89 tin. A pewter often used is tin, 92, lead, 8. Rees's alloy is tin 20, gold i, silver 2. Common Solder is an alloy of tin and lead. [Fine solder is 33.3 lead to 66.6 tin. Common solder is equal parts tin and lead; coarse solder is 66.6 lead to 33.3 tin]. 286. Compounds of tin. Stannous Chloride : This substance, known to the dyer as " tin salt," is made by dissolving metallic tin in hydrochloric acid. It may also be prepared by distilling tin filings with mer- curous chloride. Its formula is SnCl 2 ,2H 2 O; molecular weight, 224.5. It is use d locally. It is poisonous; the antidotes are baking soda, magnesia, milk, and white of egg. Tin dissolved in nitrohydrochloric acid yields INORGANIC CHEMISTRY. 199 stannic chloride, SnCl 4 . The two chlorides of tin in con- nection with auric chloride yield purple of Cassius. (See section 258.) 287. Palladium. Symbol: Pd. Latin name: Palladium. Equivalence: II and IV. Specific gravity : 11.80. Atomic weight: 106. Re- vised atomic weight: 105.737. Electrical state: + Fusing point: lower than platinum, but requires oxy-hydrogen blow-pipe. Length of bar, etc.: i.ooio; (i2th rank). Wt. of cubic ft. in Ibs.: 736.6. Tenacity: \\y 2 (Lead = i): (7th rank). Malleability: inferior to platinum. Ductility: 6; (6th rank). Conducting power (electricity): i84(silver = 1000); (5th rank). Resistance to air, etc.: i; (first rank). More oxidizable than platinum at red heat. Solubility: soluble in nitric acid; attacked by iodine; aqua regia best solvent. Direct combinations: cyanogen, iodine, hydrogen, sulphur, chlorine, phosphorus, arsenic. Color and appear- ance: like platinum, or a platinum-gold alloy. Structure: native, grains of fibrous appearance. Consistence: hard as platinum. Compounds: palladium (II) and palladic (IV). Alloys: salmon-bronze. Use in dentistry; in amalgam alloys. (See section 223). 288. Platinum. Symbol: Pt. Latin name: Platinum. Equivalence: II, and IV. Specific gravity: 21.50. One of the heaviest sub- stances in nature. Atomic weight:' 197. Revised atomic weight: 196.700; (according to some, 194.8). Electrical state: +. Fusingpoint: above 3500 in oxyhydrogen flame, or coal-gas and oxygen flame. Length of bar, etc.: 1.0009; (i3th rank, least expansible of the 13 metals). Wt. cubic ft. in Ibs.: 1.344. Tenacity: 15, compared with lead; (4th rank). Malleability: 5; (5th rank). Ductility: 3; (3d rank). Conducting power (heat): 8; (8th rank). Con- ducting power (electricity): 180 (silver = 1,000): (6th 200 DENTAL CHEMISTRY. rank). Resistance to air, etc.: i; (ist rank). Solubility. dissolves slowly in aqua regia. Acted on by fused alka- line hydrates at red heat. Direct combinations: sulphur, phosphorus, arsenic, silicon, chlorine. Absorbs and con- denses gases when in finely divided state. Color and appearance', white with tinge of blue, brilliant but less than silver. Structure', (native) rounded grains; some- times octahedral crystals. Consistence', hard as copper. Compounds', platinous (II), and platinic (IV). Alloys: with most metals. Gold, silver, lead form easily fusible alloys with it. Use in dentistry: in amalgam alloys, for plates of continuous gum teeth, for pins for fastening porcelain teeth to the rubber or cellu- loid plate. Metallic platinum does not amal- gamate with mercury, but spongy platinum unites with the latter when triturated with it in a warm mortar or in contact with acetic acid. (See, however, Rollins's process, following below). In finely divided state it is used as a coloring matter for artificial teeth. Preparation of platinum for coloring the enamel of artificial teeth. The ordinary platinum sponge is too coarse to produce the best results without much grinding. Rollins proceeds as follows: Dissolve twenty grammes of platinum in aqua regia and evaporate to a thick syrup, then add one hun- dred grammes of caustic potash and boil. To this mixture add fifty grammes of grape sugar and boil ten minutes. Wash thoroughly by decantation and dry the residue, which is platinum in an exceedingly fine state. To pre- pare what is to be called " Platinum Color" use feldspar eight grammes, this platinum five hundred milligrammes. INORGANIC CHEMISTRY. 201 Mix and grind five minutes on slab. Use this mixture to add to uncolored spar for the enamel. 289. Platinum metals: these are platinum, rhodium, palladium, ruthenium, and iridium. Occurrence: the chief supply of platinum, which, like gold, is found free, is derived from the Ural Mountains. The Russian platinum digging's are near Bogoslowsk, Miask, New- jansk, and Nischnei Tagilsk. It is also found in Brazil, Peru, Columbia, California, and Borneo. The Russian platinum is always associated with other metals: analysis showed in one specimen, 75.1 platinum, i.i palladium, 3.5 rhodium, 2.6 iridium, 0.6 osmiridium, 2.3 osmium, 0.4 gold, i.o copper, and 8.1 iron.* Preparation: the platinum is dissolved in fused galena, a little glass is introduced to melt over the surface, and a quantity of litharge, equal in weight to the galena, is gradually added. Sulphurous acid gas, from the lead sulphide and lead oxide, is formed, leaving metallic lead in combination with the platinum, free from osmium and iridium. The lead- platinum combination is then treated in a cufi- ellation furnace, that is, a furnace containing a cup, made of bone ash; the lead removed as * The annual product is two or three tons, of which the United States furnish about 200 ounces. It is worth about f 15 an ounce, and the price tends to rise in consequence of the demand for it for use in electric lighting. 202 DENTAL CHEMISTRY. an oxide, leaving; the platinum in spongy state on the cupel. The spongy platinum is refined in a lime furnace, by the heat of an oxy-hydrogen, or coal g-as and oxyg-en flame. 290. Compounds of platinum: platinic chloride, Pt C1 4 , is formed when metallic platinum is dissolved in aqua regia. It is a reddish, deliquescent substance readily soluble in water and in alcohol. 291. Iridium. Symbol: Ir. Latin name : Iridium. Equivalence: II, IV, VI. Specific gravity: 21.1. Atomic weight: 192.7. Re- vised atomic weight: 192.651. Electrical state : +. Fusing point: fusible in oxyhydrogen blow-pipe; more refractory than platinum. Resistance to air: unalterable in air. Sol- ubility: not soluble in aqua regia unless alloyed with plat- inum. Direct combinations: sulphur, chlorine, iodine, oxygen. Color and appearance : white, like polished steel. Consistence: very hard, brittle. Compounds: iridic, iridious, hypoiridious. Alloys: with platinum. Value in dentistry : for alloy with platinum in manufacture of plates and wire. 292. Silicon. Symbol: Si. Latin name: Silicium. Equivalence: II and IV. Specific gravity: 2.49. Atomic weight (appro x.\. 28.2. Atomic weight (revised}: 28.1950. Electrical state: Solu- bility: in melted zinc, etc. Fusing point: above melted iron. Preparation: made by action of sodium on potas- sium fluo-silicate. Properties: occurs in three forms somewhat resemb- ling carbon. Is an amorphous, nut-brown powder. In combination, as silica, SiO 2 , found in sand, rocks, etc. 293. Compounds of silicon: the most important is silica, SiO 2 . Silica occurs in nature as quartz crystal and in sand. Is found in animal tissues. Compounds are INORGANIC CHEMISTRY. 203 silicates. Insoluble in water or acids, infusible except by oxyhydrogen flame, sp. gr. 2.66. Percentage composition, silicon, 48.04, oxygen, 51.96. Used in manufacture of porcelain teeth. Use in dentistry: dentists use silica under the name of silex in the preparation of arti- ficial teeth. For dental uses it is prepared by heating" to white heat, plunging into cold water, and grinding to a fine powder. 294. Titanium: titanium itself is not used in dentistry, and the only compound of interest is the dioxide, titanic oxide, TiO 2 , which occurs native in several different forms, viz., as, the minerals rutile and anatase, and as brookite. Rutile is the most abundant, and is used, ground up, as a coloring matter for artificial teeth. If ground moderately coarse it imparts a yellow of redder cast than when ground fine. It is used for the yellow color of the body of porcelain teeth. 295. Carbon. Symbol: C. Equivalence: II and IV. Atomic weight (appro x. }: 12. Atomic weight (revised] : 11.9736. Electri- cal state: . Fusing point: infusible. Properties: affinity for oxygen, hydrogen, sulphur. Infusible, non-volatile, unalterable solid. Absorbs gases, disinfectant. 296. Dental uses. In the form of charcoal, coke, and anthracite coal, carbon is used in the dental laboratory. In the form of animal charcoal and of wood charcoal it is used in dental medicine. Charcoal is prepared on a large scale by burning wood in heaps with limited supply of air. Carbo ligni is the official preparation. 204 DENTAL CHEMISTRY. Coke is the substance left in retorts after coal has been distilled in the production of illuminating gas. Anthracite coal is the result of the slow decay of vege- table matter. It often contains 96 to 98 per cent, of carbon. Carbo animalis purificatus consists of carbon and several salts of calcium, notably the phosphate and the carbon- ate. Charcoal, and especially animal charcoal, has the power of absorbing gases, of destroying noxious odors, and of filtering coloring matters from solutions of organic sub- stances. One volume of wood charcoal at 2i2F will absorb 90 volumes of ammonia gas, 55 volumes of sulphur- etted hydrogen, and 9 volumes of oxygen. It is admin- istered internally to counteract the effect of poisons, as, for example, strychnine, but should be removed by the stomach pump. 297. Illuminating gas is made by subjecting bitumi- nous coal to the action of dry heat yi retorts. The coal is heated to bright redness, and the products given off from it are passed through a series of upright tubes, in form of an inverted U, called condensers, where the tar, steam, and ammonia are condensed. The gas is then passed through a series of large boxes called purifiers, in which it is purified by coming into contact with various substances as fresh slaked lime or a mixture of sawdust and iron oxide, and then it goes to a large tub-shaped vessel called the gasometer to be stored until needed. It is a mixture essentially of hydrogen and marsh-gas mixed with variable proportions of olefiant gas, acetylene, the oxides of carbon, etc., etc. [Much of the illuminating gas now used is the so-called " water-gas," which con- tains usually a considerable amount of carbon monoxide, and is made by decomposing steam and then carburet" ting the gases formed]. INORGANIC CHEMISTRY. 205 298. Compounds of carbon. Carbon forms two compounds with oxygen, namely, carbon monoxide and dioxide. Carbon monoxide, CO, is formed when carbon is burned in deficient supply of air. Molecular weight, 28; density, 14; sp. gr., 0.9678. Is a gas. Colorless, insipid, very poisonous, insoluble, com- bustible. Called also "carbonic oxide gas." Carbon dioxide, CO 2 , is a product of combustions and of fermentation. Made by pouring an acid on a carbonate, as sulphuric acid on marble or limestone. Molecular weight, 44; density, 22; sp.gr., 1.529. Colorless, odorless gas, present in air, water, breath, heavier than air. Nar- cotic. Slightly acid taste. Very soluble in water. Com pounds are carbonates. Carbonic Acid gas, known to chemists as carbonic dioxide, or carbon dioxide, is a constituent of the breath, is found in small quantities in the atmosphere, and is a product of fermentation. It is not a true acid, as defined in this book, but an anhydride, carbonic anhydride, CO 2 . The hydrated acid is not found, but its salts exist, as, for example, the various carbonates, like sodium carbonate, Na 2 CO 3 . 299. Carbon Bisulphide. Synonyms: carbon bisulphide, carbon bisulphuret or bisulphuret of carbon. Official name, Carbonei Bisul- phidum. Theoretical constitution: CS 2 , one atom of carbon and two of sulphur. Molecular weight, 76. Preparation: made by passing fumes of sulphur over red hot charcoal. Properties: mobile, colorless liquid of disgusting odor except when pure. Very volatile. Dissolves iodine, sul- phur, phosphorus, oils, fats, caoutchouc, etc. Sometimes used as local anaesthetic. 206 DENTAL CHEMISTRY. Use in dentistry: to dissolve caoutchouc. PENTADS AND HEXADS. 300. None of the pentads are used in dentistry except those classified as triads, when varying in equivalence. The following list shows hexads of importance: TABLE 24. IMPORTANT HEXADS. Manganese. Iron. Nickel. Cobalt. "j Hexads 1 positive f to J hydrogen. ] Hexad Chromium. >- negative to ) hydrogen. 301. Manganese. Symbol: Mn. Latin name: Manganesium. Equivalence: II, IV, VI; also a pseudo-triad. Specific gravity : 8.01 to 8.03. Atomic weight (approx.}: 53.9. Atomic weight (revised}: 53.9060. Electrical state.: + Properties: grayish white metal of but little lustre, hard, brittle, and nearly as re- fractory as platinum. 302. Compounds of manganese. The only important compound for dental uses is the dioxide, MnO 2 , which, in minute quantity, imparts a pur- ple color to the frit, probably due to formation of an oxy- silicate. A silicate is also used in enamels; it is a yellow amorphous powder turning brown on exposure to air and soluble in dilute acids. Manganese dioxide occurs in nature as the mineral pyrolusite. It is a heavy, black, crys- talline mineral insoluble in water. When heated to redness it liberates oxygen. INORGANIC CHEMISTRY. 207 303. Iron. Symbol: Fe. Latin name: Ferrum. Equivalence: II, IV,* VI. Specific gravity : 7.79107.84. Atomic weight v 56. Revised atomic weight : 55.9130. Electrical state : + Fusing point: 35OOF (wrought iron). Ordinary, 29 O 3 . 341. Mint: oil of peppermint, Oleum Menthas Piper- itae, is of greenish-yellow color, becoming reddish by a"ge. It has a strong aromatic odor, and a warm, camphorous, pungent taste, succeeded by a sensation of coolness, when air is drawn into the mouth. 342. Neroli: the oil obtained from orange flowers is termed oil of neroli, and is a volatile oil of delightful odor. 343. Pyrethrum: the oil dissolved in ether is used in odontalgia. Pyrethrum or pellitory is a powerful local irritant. 344. Rose: this substance, known also as attar or ottar of rose, is nearly colorless, concrete below 8oF., liquid between 84 and 86F. It has a powerful and diffusive ORGANIC CHEMISTRY. 231 odor, is slightly soluble in alcohol, and of a slightly acid reaction. The official name is Oleum Rosae. Probably all the oil of rose of the Turkish market is adulterated. It should, when slowly cooled to 5OF., deposit a crystal- line substance, called a stearopten, free from oxygen. 345. India-rubber: caoutchouc or India- rubber is the dried, milky juice obtained from several trees growing; in the tropics. When freshly obtained the juice is acid in reaction. It contains several hydrocarbons which are soluble in ether, benzole, carbon disulphide, chloroform, and turpentine, but insoluble in water and in alcohol. It is hard and tough in the cold, softens on heating, be- comes elastic, melts, and, on cooling, is soft and viscid. It combines directly with sulphur, hardening, and forming Vulcanized India-rub- ber; carbon disulphide is used to facilitate the union. Mixed with half its weight of sul- phur, Vulcanite or Ebonite is formed.* Dental rubber: India-rubber is prepared for vulcanizing by incorporating with it either sulphur alone, or some of its compounds; a coloring matter is also added, in many cases mercuric sulphide (vermilion) but white clay, oxide of zinc, and calcium carbonate are also used. Para rubber is the kind used, the ver- milion being added when a " red rubber" is desired, and the oxide of zinc or some form of . *Both India-rubber and gutta-percha resist the action of most chemical substances, and hence are dissolved with difficulty. 232 DENTAL CHEMISTRY. aluminium silicate, as white clay, when a "white rubber." "Black rubbers" are the result of vulcanizing; the rubber directly with sulphur, no pigment being- added. It is claimed that the various pigments, when in large percentage, produce soft, inflexible rub- bers. Difference in shade of red is supposed to be due to difference in percentage and kind of vermilion used. 346. Gutta-percha resembles caoutchouc in chemical characters, and is the hardened milky juice of an Indian tree. It is harder tJian rubber and less elastic, but becomes quite soft in hot water, and can then be moulded. When purified it is brown-red, of a density of 0.979, electrified by friction, and is a very slow conductor of electricity. It has, at ordinary temperatures, considerable tenacity, is as strong as leather but less flexible. At ii5F., it is pasty and still very tenacious. At 103 and i04F., it may be spread out into sheets, or drawn out into threads or tubes. Its sup- pleness and ductility diminish as the temper- ature is lowered, and it has not at any tem- perature the elastic extensibility of caout- chouc. Softened by heat, it may be worked by pressure into any shape. It is soluble in carbon disulphide, benzene, chloroform, in hot oil of turpentine. // is insoluble in water, in which it is best preserved, resists alkalies, hy- ORGANIC CHEMISTRY. 233 drochloric acid, and hydrofluoric acid. Giitta- percha alters, and this fact must not be for- gotten. If in thin sheets or threads, at a temperature of from 77 to 86F., it gradually becomes useless and gives off a pungent odor. The change is due to oxidation. Use in dentistry: gutta-percha is used as a plastic filling material. It is an ingredient of Hill's Stopping. Together with oxide of zinc, it is used as a filling material. According to Flagg it is easy to raise the gutta-percha to any reasonable degree of 'temperature at which it becomes plastic, by simply increasing the relative quantity of inorganic admixture, but this very increase is destructive to the value of the gutta-percha. As found it is often adulterated, but owing to advanced knowledge pure gutta-percha can be more readily ob- tained than formerly. We have to distinguish between two forms of adulteration, those used for the purpose of fraud in weight, that is, foreign substances such as small stones, sand, and pieces of bark; and, second, those that combine with it to injure its strength, pitch, tar, etc. But, strange to say, none of these latter interfere with its hardness when cold. This last adulteration the dentist has to guard against, and therefore to test its strength it should be slightly warmed. The two best grades are known to the trade as " G. P. A." and " G. P. F." The G. P. A. is of a light-brown color, and the G. P. F., when sheeted, is a beautiful marbled white. (Meriam). For dark-colored stopping Meriam uses G. P. A., and for light, G. P. F., and for medium, the two mixed. 234 DENTAL CHEMISTRV. For convenience they had best be bought sheeted, keeping in mind that the different forms in which it is offered do not indicate different varieties. The gutta percha should always be fresh, and feel soft and unctuous in handling. The splint gutta percha, often called pure, which is occasionally recommended, is adulterated with tar or resin, and it can readily be seen that such adulteration must injure its fibre. Pure gutta percha can be obtained by dissolving in chloroform, drawing off with a siphon, and then distill- ingoff the chloroform, or dissolving in disulphide of carbon and filtering through animal charcoal. These methods need not be used to-day, as G. P. F. sheeted will be found white enough for all purposes. (Meriam). Meriam uses oils for softening the surface. 347. Artificial gutta perchas are now made. Accord- ing to Zingler copal resin, sulphur, petroleum, casein, tannin, and ammonia are the substances used in manufac- ture. 348. Camphor. Theoretical constitution: Ci H 16 O. It is sometimes classified among the aldehydes, but for convenience will be considered among the hydrocarbons on account of its oils. Camphor is a concrete substance derived from camphor-laurel tree ; soft, tough cakes, easily powdered on addition of a little alcohol; translucent, strong frag- rant odor, aromatic bitter cooling taste, volatile, inflam- mable; lighter than water; slightly soluble in water, but soluble in alcohol, ether, chloroform; dissolved in alcohol forms spirit of camphor, from which it may be precipitated by water; dissolved in water, containing a little alcohol and a little magnesium carbonate, forms camphor-water: boiled with bromine, forms mono-brornated campJwr, Ci H 15 BrO. Gum-camphor has a rotatory movement on water ORGANIC CHEMISTRY. 235 which is stopped by the least trace of fat. Camphor is a local irritant, stimulant, and poison. It is a constituent of celluloid. Spirit of camphor is locally employed in dentistry to allay pain. With ether it is used as a local anaesthetic. Taken internally, it is poisonous, although recovery from its effects are usual. The treatment consists in use of emetics and castor oil. 349. The official Oleum Camphorce is made by heating camphor. It is a light reddish-brown fluid, of the taste and odor of camphor. 350. Resins, Balsams, Gum-resins, etc.: resins are oxidized terpenes, produced by the oxidation of the essen- tial oils of plants. They are brittle, solid, transparent bodies, of no well marked odor or taste, soluble in alco- hol, insoluble in water, combustible, yield a lather with alkalies. Resins are employed in the manufacture of varnishes: copal resin is prepared by simple exudation. 351. Guaiacum resin is prepared by destructive dis- tillation, and in other ways, from a tree growing in South America and the West Indies. It comes in large, irregu- lar, semi-transparent, brittle pieces, externally of an olive or deep green color, internally red. It has a slight bal- samic odor, and leaves a hot acrid sensation in the mouth and throat. It is wholly soluble in alcohol, partly soluble in water. 352. Gum-resins are resins mixed with gum, sugar, etc., inplants, and are insoluble in water, soluble in glycerine, turpentine, and strong alcohol. They are a mixture of several bodies, hence have not a definite chemical formula. 353. Myrrh is an exudation from an Arab- ian or African tree, and is a gum-resin. It is 236 DENTAL CHEMISTRY. of reddish-yellow or reddish-brown color, of fragrant, strong, peculiar odor, and bitter, aro- matic taste. It is translucent, pulverizable, and brittle. It should dissolve in fifteen times its weight of water, when rubbed up with an equal weight of sal-ammoniac. It has a resinous fracture, and makes a light yellowish powder. Inferior kinds are darker, less trans- lucent, and less odorous. The resin of myrrh is called myrrhic acid. Myrrh forms an emul- sion with water, and is soluble in alcohol and in ether. An old tincture of it has been shown to have an acid reaction.* It is used in dentistry as a local application. The powder is also used in dentifrices. . 354. Gums are non-volatile, colloid, almost tasteless bodies, occurring in the juices of plants. (See Carbohy- drates). 355. Sandarach : sandarach is a substance composed of three resins, which are of different solubility in alco- hol, ether, and turpentine. Sandarach comes in tears, which are small, and of a pale yellow or brown color, and more or less transparent: they are dry and brittle. San- darach is inflammable, and melts on being heated. It is soluble in alcohol, ether, and warm oil of turpentine. It is used in dentistry, dissolved in alcohol, as a varnish. The name sandarach is sometimes given to the disul- phide of arsenic, which, however, has nothing to do with the resin sandarach, and should not be confused with it. 356. Lac: lac consists of resin, soluble coloring matter, lacin, wax, and salts. The resin is about 90 per cent, of *Brackett. ORGANIC CHEMISTRY. 237 lac. Shell Lac is one of the commercial varieties of lac and is an exudate from several kinds of trees growing in the East Indies; it is caused by punctures of insects. It is prepared from the crude lac by melting, straining, and pouring on a flat, smooth surface. Shellac comes in thin, shining, hard, brittle fragments, odorless, insoluble in water, but freely soluble in alcohol, more so in warm alcohol. It is used in dentistry as a varnish. 357. Naphthalene: naphthalene or naphthalin, C 10 H 8 , or (Ci H 7 )H, is a coal tar product, distilling from this sub- stance between 356 F. and 428. It crystallizes in large, white, rhombic plates, of silvery lustre, and characteristic odor, and of a biting, somewhat aromatic taste. It melts at 174.5 F., and boils at 420 to 428. It volatilizes very sensibly, even at ordinary temperatures. It is inflamam- ble, burning with a luminous and very smoky flame. Its specific gravity is 1.15. When melted, it dissolves sul- phur, phosphorus, iodine, and indigo. It is insoluble in water, but soluble in hot alcohol, benzene, and ether, also in wood-spirit, chloroform, carbon disulphide, petroleum spirit, fixed and volatile oils. It is insoluble in alkaline or dilute acid solutions, slightly soluble in concentrated acetic acid. It is an antiseptic substance, and, when used as dressing, should be thoroughly purified by recrystalliza- tion from alcohol or by distillation with steam. It is not corrosive, and when entirely pure is odorless; it is, how- ever, almost impossible to obtain it free from the charac- teristic odor, but the latter may be entirely overcome by adding a few drops of oil of bergamot to 4 oz. of the naphthalin. In powdering naphthalin, addition of a lit- tle alcohol greatly facilitates the operation. As an anti- septic, the best results have been obtained from use of it in powdered form. Combinations of this substance with iodoform and with boric acid should make valuable anti- septics. The naphthalin made in this country can be 238 DENTAL CHEMISTRY. reduced to a moderately fine powder; the pure, imported naphthalin cannot be reduced to powder except when, very cold. Attention should be paid to the fact that it is inflammable. 358. Naphthols : Ci H 7 O. There are a number of these compounds. What is commercially known as " hydro- naphthol," is properly, beta-hydio-naphthol, has powerful antiseptic properties (1-7200 limit) and is non-poisonous. [That which is called in commerce "beta-naphthol," is properly, according to Wolff, betanahydro-naphthol, and according to Bouchardat, Kaposi, Miner, Piffard, and others, is poisonous. To distinguish them dissolve in alcohol. Hydronaphthol (non-poisonous) dissolves in 10 parts alcohol, with a deep-brown coloration, while beta-naphthol dissolves without coloration]. Naphthol used medicinally crystallizes in thin, shining plates, readily soluble in alcohol, ether, chloroform, and fatty oils. 359. Ethyl series of radicals, alcohols, and carbohy- drates. Before considering the alcohols, it is well for the student to become familiar with the ethyl series of radi- cals. TABLE 25. ETHYL SERIES OF RADICALS. ~ Hydrides of, or Marsh Compound Radicals. Gases Methyl, CH 3 Methane, CH 3 H or CH 4 T?-U i r u (marsh gas). fctnyi, UH 5 Ethane, C 2 H 5 H or C 2 H 6 Propyl, C 3 H Propane, etc. Butyl, C 4 H 9 Butane, etc. Amyl, C 5 Hn etc., etc. etc., etc. etc., etc. ORGANIC CHEMISTRY. 289 T A B L E 25 Continued. Oxides or Ethers. Hydrates, or Alcohols. (CH 3 ) 2 O, or C 2 H 6 O, CH 3 HO, or CH 4 O, wood methyl ether. spirit, methyl alcohol. (C 2 H 5 )A or QH 10 O, C 2 H 5 HO, or C 2 H 6 O, ordin- e'thyl ether. ary alcohol, etc etc. etc. etc. etc. C 5 H U HO, or C 5 H 12 O, amyl etc. alcohol, fusel oil. 360. Theoretical formation: the starting point in form- ing these compounds is with the hydrates or alcohols, and not with the compound radicals themselves. For exam- ple, when an alcohol, as C 2 H 6 O, is oxidized with oxygen limited in amount, there results what is called an aldehyde or dehydrated alcohol, as C 2 H 4 O. two atoms of hydrogen being withdrawn and no oxygen added. If, however, the alcohol is oxidized vf \\hplentiful oxygen, an atom of oxyen is added in place of the two atoms of hydrogen withdrawn, and an acid is formed; thus, from C 2 H 6 O comes C 2 H 4 O 2 , or acetic acid. 361. Tabular view of aldehydes and acids of ethyl series of radicals: Radicals. Alcohols. Aldehydes. Acids. Methyl. CHa CH 4 O CH 2 O CHsjO* (forming Ethyl, C 2 H 5 C 2 H 6 O C,,H 4 O acid). etc. C2H 4 O 2 (acetic etc. acid). Compounds of the hydrocarbon radicals with chlorine, bromine, etc., are called haloid ethers, while salts proper of the hydrocarbon radicals are called compound ethers. Ethers are, in general then, compounds of the hydrocarbon radicals other than the marsh gases, alcohols, aldehydes, and acids. (See section 407). 362. Alcohols:* alcohols may be regarded *It will be noticed that the chemist's conception of alcohols in- cludes many substances, such as glycerine, which resemble little our ordinary alcohol. 240 DENTAL CHEMISTRY. as substances derived from hydrocarbons by replacing one or more hydrogen atoms by the radical hydroxyl, HO. Thus ethyl hydride, (C 2 H 5 )H, becomes ethyl alcohol, (C 2 H 5 ) HO, by exchanging one atom of H for the radical HO. Alcohols are called monatomic, diato- mic, or triatomic, according as HO replaces one, two, or three atoms of H in a hydrocar- bon. Ordinary alcohol is a monatomic alcohol, diatomic alcohols are also called glycols, and of triatomic alcohols glycerine is a notable example. The alcohols are hydrates, resembling the inorganic hydrates, as, for example, potassium hydrate, KHO; common alcohol is ethyl hydrate, C 2 H 6 HO. 363. Alcohol. Synonyms: ethyl alcohol, common alcohol, ethyl hydrate, ethylic alcohol, Spirit of Wine. Theoretical constitution: C 2 H 5 HO, hydrate of the radical ethyl, two atoms of carbon, six of hydrogen, and one of oxygen; formula sometimes written C 2 H 6 O. Molecular weight, 46. 24 parts by weight of carbon, 6 of hydro- gen, and 16 of oxygen. . Preparation: alcohol is obtained by the fer- mentation of saccharine liquids, brought about by the growth of a microscopic plant called yeast. ORGANIC CHEMISTRY. 241 Grape sugar or glucose yields alcohol when fermented: C 6 H 12 6 2 C0 2 + 2C 2 H 5 HO, Glucose carbon alcohol .dioxide. The fermented liquid is distilled, and a dilute alcohol obtained; repeated distillations will finally give an alcohol containing about 14 per cent, of water. To obtain alcohol, free from from water, the former must be mixed with half its weight of lime, and the alcohol distill- ed off from the mixture. Properties: absolute alcohol containing no water is a transparent, mobile, volatile, color- less liquid of an agreeable, pungent odor, characteristic of itself, and a burning taste, boiling at 173 F., of a sp. gr. 0.794, an d has never been solidified. It is neutral in reaction, inflammable, burning with a non-luminous flame, dissolves resins, essential oils, alkaline hydroxides, alkaloids, calcium chloride, mer- curic chloride, and many other substances, but especially those rich in hydrogen. Mixed with water, a contraction of volume occurs, with production of heat. Its attraction for water is very great; it absorbs moisture from the air and abstracts it from membranes, tissues, etc. Shaken with pure, colorless sulphuric acid, it should not become colored. ( Presence of fusel oil). It is poisonous. . 364. Absolute alcohol: commercial usage accepts as 242 DENTAL CHEMISTRY. absolute, alcohol of not less than 99.5 to 99.7 per cent, of sp. gr. (at 60 F.) 0.7938, boiling at 172.4 F. Alcohol, U. S. P., is 91 per cent, by weight of real alco- hol, or 94 per cent, by volume, the rest being water. Alcohol dilutnm is 45.5 per cent, by weight, or 53 per cent, by volume. Spirit of wine (rectified spirit] is 84 per cent, by weight. Proof-spirit is 49 per cent. Spirits are substances distilled from fermented liquors; brandy, whisky, rum, and gin are examples. They con- tain from 35 to 45 per cent, of alcohol by volume, although some specimens run as high as 50 per cent, (brandy, rum) and some as high as 60 per cent., (whisky). Wines contain from 6 to 25 per cent., sherry and port being the strongest. Beers average 4 to 5 per cent., though some are very weak, containing only I per cent. Use in dentistry: alcohol is used in dentistry for vari- ous purposes, as styptic, antiseptic, obtunding agent, for drying cavities, in lotions, gargles, etc., etc., and as a sol- vent and preservative. Toxicology: the stomach pump should be used in cases of poisoning by alcohol, and, if the bladder is distended, use of the catheter is indicated. Cold affusion to the head, fresh air, ammonia, and strong coffee are valuable, especially if the stupor be intense. 365. Tinctures are alcoholic solutions of the medicinal agents in plants, prepared by maceration, digestion, or percolation. 366. Fluid Extracts: these preparations are concent- rated, and represent considerable drug-power in small bulk. Each Cubic centimetre represents a gram of the crude drug. 367. Wood Spirit: methyl alcohol, or wood spirit, is methyl hydrate, CH 3 HO, called pyroligneous ether,. ORGANIC CHEMISTRY. 243 pyroxylic spirit; wood naphtha is largely composed of it. It is made by distillation from wood. It is a liquid of spirituous odor, and is inflammable.* 368, Fusel Oil is amylic alcohol, C 5 H U HO, hydrate of the radical amyl, called also potato spirit. Fusel oil pro- per is a mixture of several alcohols, of which amylic alcohol is one. It is made from residues left in the still, after common alcohol is distilled off. It has a peculiar, irritating odor, and is very poisonous. Is produced in the fermentation of grain, hence often an impurity in whisky. 369. Glycerine. Theoretical constitution: this substance is a triatomic alcohol derived from propane (C 3 H 7 ) H, by substitution of sHO for three atoms of H. The formula for propane may be written C 3 H 8 ; take away three atoms of H and we have C 3 H 5 ; add 3HO and there results C 3 H 5 3HO, or C 3 H 8 O 3 . Glycerine is, then, the hydrate of a radical, C 3 H 5 , called glyceryl, tritenyl, or propenyl. Hence the modern term for glycerine, namely, tritenyl hydrate. Properties and uses: glycerine is obtained from fats by treatment with alkalies, soap be- ing formed and glycerine liberated. The pro- cess is called saponiiication. Pure glycerine is a colorless, or light straw, yellow, thick, syrupy liquid, unctuous, inodorous, of sharp, sweet taste; soluble in water, alcohol, and oils, but not in ether or chloroform. // is valuable *Methylated spirit is composed of 9 parts ordinary alcohol to i part wood alcohol. 244 DENTAL CHEMISTRY. as a solvent for many medicinal substances, official solutions of which in glycerine are call- ed glycerites. Glycerine is permanent and does not evaporate or dry at any tempera- ture. Official Olycerinum has a sp. gr. of i .25. It dissolves about fifty familiar substances used in medicine, among" which are boric acid, borax, carbolic acid, creasote, potassium iodide, arsenic, alum, zinc salts, morphine salts, tannate of quinine. Use in dentistry: its value in dentistry is as a solvent, and when combined with other sub- stances, as an emollient and solvent. Teeth lotions contain glycerine, as for example the following;: tincture of quillaia, eau-de-cologne, water, borax, glycerine, with coloring. Glycer- ine is found to be of service in the process of vulcanizing India rubber, giving the latter the property of resisting oils and fats. Glycerine may be used to detect carbolic acid adultera- tion in creasote. (See Creasote). 370. Glycerites: these are solutions of various sub- stances in glycerine. Those most commonly used in dentistry are the glycerites of carbolic acid, gallic acid, tan- nic acid* sodium borate, starch, thymol, and pepsin. The glycerite of borax (sodium borate) becomes acid and unfit for use after a time. 371. Boroglyceride : boroglyceride, C 3 H 5 BO 3 , is glyceryl borate, or tritenyl borate, made by heating boracic acid, H BO 3 , with glycerine, C 3 H 5 3HO, or C 3 H 8 O 3 : *The glycerite of tannin is used as an application to spongy gums. ORGANIC CHEMISTRY. 245 C 3 H 8 O 3 -f H 3 BO 3 + heat = ' C 3 H 5 BO 3 + 3 H 2 O. Glycerine. boracic acid. boroglyceride. water. 6 parts of boric acid in fine powder and 9 of glycerine are heated together in a porcelain dish at 302 F., stirring well until aqueous vapors cease to be given off, and a homogeneous, transparent mass is formed, which becomes hard and tough on cooling. Care is taken not to heat the mixture too strongly, as that would render the pro- duct dark colored. Boroglyceride is a colorless, tough, solid substance, soluble in water, and in alcohol, odorless, tasteless, not poisonous. // is used in dentistry as an anti- septic, and, in combination with sodium sulphite, for bleaching teeth. 372. Sodium glyceroborate : this substance is made by heating equal parts of sodium borate with glycerine. Soluble, deliquescent, odorless, antiseptic. 373. Calcium glycerobor ate: made by heating equal parts of calcium borate with glycerine. Soluble, deliques- cent, odorless, antiseptic. 374. Creasote: creasote, Creasotum, is a mixture of substances, but consists chiefly of creasol, C 8 Hi O 7 , and guaiacol, C 7 H 8 O 2 . // is a product of the distillation of wood- tar, occur- ring- in the lowest layer of the distilled liquid. It is colorless, or faintly yellow, when fresh and pure, of sp. gr. 1.046, U. S. P., but usually varying; from 1 .040 to 1 .090. It boils at 3Q2-4io F. // is of disagreeable, penetrating, smoky odor, and burning, ca^tstic taste. It is soluble in 80 parts of cold water, and 24 of hot, and in all pro- portions in alcohol, ether, acetic acid, and car- bon disulphide. Ignited, it burns with a white, 246 DENTAL CHEMISTRY. sooty flame. It forms a clear mixture with collodion; precipitates solutions of gum and of albumin. On growing- old, it gradually be- comes brownish in color. It may be distin- guished from carbolic acid by not solidifying when cooled, by not coloring ferric chloride permanently, by its lower boiling point, and by being insoluble in glycerine. A specimen of creasote, if pure, should leave no stain on paper, after being dropped on it and volatilized by heat. Mixed with equal volume of collodion, it should not cause the latter to gelatinize. Creasote water, Aqua Creasoti, consists of one fluidrachm of creasote to one pint of water. Solidified creasote is made from 10 parts of collodion to 15 of creasote. Use in dentistry: creasote is used as an obtunding agent, styptic, antiseptic, to coun- teract any acid in a tooth cavity, to harden the contents of dental tubuli and render them imperishable. Toxicology: creasote is poisonous, in over- doses causing giddiness, obscurity of vision, depressed heart action, etc., etc. The treatment consists in administration of white of egg, milk, wheat flour, and stimu- lants, as aromatic spirit of ammonia. An emetic should be first administered. ORGANIC CHEMISTRY. 247 375 Phenyl alcohol or carbolic acid.* Synonyms: phenol, phenylic alcohol, phenic acid. Official name, Acidum Carbolicum. Theoretical constitution; carbolic "acid" is really an alcohol, C 6 H 5 HO, or hydrate of the radical phenylf, C 6 H 5 , graphically CH CH / x HC C-O-H x / HC = CH It is by weight composed of 72 parts carbon, 6 of hydrogen, and 16 of oxygen. Molecular weight, 94. Preparation: crude carbolic acid is obtained by distilling coal-tar between the temperatures of 302F. and 374F. Official carbolic acid is a. pure phenol, ob- tained by distilling crude carbolic acid between 338F. and 365, separating from other pro- ducts, and purifying by repeated crystalliza- tion. Properties: carbolic acid, in the pure state, forms needle-shaped, colorless, interlacing crys- tals, neutral in reaction, having a characteristic, slightly aromatic odor, and pungent, caustic taste; the taste is sweetish when the acid is * Called " acid" because of its ready combination with bases form- ing carbolates or phenates, so-called. | This radical phenyl belongs to the aromatic series. 248 DENTAL CHEMISTRY. slightly diluted. // prod^tces a white eschar on animal tissues, having a benumbing (caustic) effect. When pure, carbolic acid is permanent in the air, and not affected by light, but the ordinary acid usually changes to pink or red. The color does not in the least impair the medicinal value of the phenol. Water dissolves 6 per cent, of phenol, according to Squibb. Five parts of phenol dissolve in I part of alco- hol; 4 in one of ether; 3 in I of chloroform; 7 in 2 of glycerine ; 4 in 7 of olive oil. It is also soluble in benzol, carbon disulphide, fixed and volatile oils. Variations in the melting and boiling points of phenol are due to the greater or less proportions of water in it. Phenol is liquid at ordinary temperatures, when it contains 8 to 10 per cent, of water. The best grades in the market con- tain at least 2 per cent, of water, and often over 4. One volume of liquefied carbolic acid, containing 5 per cent, of water, forms, with I volume of glycerine, a clear mixture, which is not rendered turbid by the addition of 3 volumes of water (absence of creasote and cresylic acid). Car- bolic acid should have no odor of creasote nor of volatile sulphur compounds. A clean, sweet, phenol odor is one of the best signs of good quality in carbolic acid. It should also be hard and dry. An anhydrous acid, fused with from 4 to 5 per cent, of water, should, on cooling, become a solid mass of crystals again. The crystals become liquid at a temperature of from 96.8F. to 197.6. When reddened and liquefied, carbolic acid resembles creasote, but gives, dissolved in water, a per- manent violet-blue with ferric chloride, while creasote gives a blue which changes to green then to brown. The crystals may be prepared, for antiseptic use, by warming the bottle till they liquefy, then adding a few drops of ORGANIC CHEMISTRY. 249 glycerine. Carbolic acid is a valuable antiseptic. It coagu- lates albumin and is poisonous. Death has followed ex- ternal application of the acid, in large quantity, to exten- sive surfaces. Use in dentistry: as an antiseptic, disinfect- ant, styptic, escharotic, obtunding- ag-ent, local anaesthetic, etc., etc. Toxicology: carbolic acid is a powerful poison, being" corrosive and also producing coma, the acid being rapidly diffused, and the odor of it, after death from poisoning, noticed everywhere throughout the body, even in the brain. The treatment is to give emetics, as, for example, apomorphine hydrochlorate sub- cutaneously, then raw eggs ad libitum, and magnesia suspended in a mixture of olive and castor oils; lime water with sugar is also recommended. The coma must be treated as in cases of opium poisoning, by artificial res- piration, galvanism, etc., etc. Chances of recovery from poisonous doses of the acid are not good. The urine should be watched, when carbolic acid is being used, and if it becomes dark-colored, it is a sign that too much of the agent is being used. 376. Various preparations containing carbolic acid. Robinson's remedy is composed of equal parts of caus- tic potash (potassium hydrate) and carbolic acid, mixed by trituration. Chloral hydrate and carbolic acid, when mixed in pro- portion of i part of chloral to 1.7 parts of the acid, 250 DENTAL CHEMISTRY. liquefy, and the liquid is soluble in water in all propor- tions. 377. Phenates: carbolic acid, with solutions of the alkalies, forms soluble compounds called phenates or phenylates, which are capable of dissolving large. quanti- ties of phenol. 378. Phenol sodique or sodium phenate: this sub- stance, C 6 H 5 NaO, is also called carbolate of sodium, sodium phenoxide, Sodse Phenas. It is made by the direct combination of carbolic acid with sodium oxide; caustic soda and a little water are used in the reaction, v/hich is as follows: C 6 H 5 HO + NaHO = C 6 H 5 NaO + H 2 O. Carbolic acid sodium sodium water hydrate phenoxide Sodium phenate occurs in form of acicular crystals of light pinkish color, liquefied by heat. It is used in dentistry as an astringent, styptic, disinfectant, etc., etc. It is freely soluble in water. 379. Phenol terchloride : this substance is of Russian introduction, and is extemporaneously prepared by mix- ing one part of a four per cent, solution of carbolic acid with five parts of a saturated solution of chlorinated lime; the filtrate is said to be 25 times more powerful than carbolic acid. According to some authorities it may be made by passing a stream of chlorine gas through pure melted carbolic acid, until a violet color is seen. Dental uses: Phenol terchloride is used as an anti- septic and disinfectant. It is combined with iodoform, and used as a capping and filling material, incorporated with decalcified dead bone. 380. Phenol-camphor* is best obtained by heating * Synonyms: Carbol-camphor, Camphor-carbol, Campho-Phe- nique. ORGANIC CHEMISTRY. pure crystallized carbolic acid (phenol) until it fuses, and then gradually adding gum camphor; a clear liquid is obtained which is characteristic on account of its permanence. In preparing this substance, use equal parts of camphor and carbolic acid: it remains liquid for an indefinite time, and does not solidify on being sub- jected to the low temperature of a frigorific mixture of snow and sodium chloride. Phenol-camphor [C 8 H U O( ?) ] is a limpid, colorless, volatile, refractive liquid, possessing the fragrant odor of camphor, entirely extinguishing the one of carbolic acid, and has a sweetish, camphoraceous, but biting taste, not as caustic as that of carbolic acid, somewhat benumbing the tongue. It is soluble in alco- hol, ether, chloroform, and ethereal oils, but insoluble in glycerine and in water, being heavier than the latter. When ignited it burns with a smoky flame. There is reason to believe that it is a chemical compound. Dr. . Schaefer has used phenol-camphor as a local anesthetic in tooth-ache, introducing it on cotton into the cavity of a carious. tooth. This substance can be likewise used as an antiseptic. It mixes well with paraffin, cosmoline, and a number of oils. In impregnating cotton gauze (antiseptic gauze) phenol-camphor may be used as a substitute for carbolic acid. Phenol-camphor is less irritating, less caustic than carbolic acid, and has also the advantage of possessing a pleasant odor. It is used in dentifrices. 381. Resorcin: this substance has for its formula C 6 H G O 8 , or better C 6 H 4 J H Q from which it will be seen that it differs from carbolic acid, in that the radical HO has been substituted for one atom of hydrogen, carbolic acid being C 6 H 5 HO, and resorcin, C 6 H 4 2HO. It is made from gum-resins, such as galbanum, extract of sapin wood, or Brazil wood, by fusing them with caus- tic potash. It occurs in the form of colorless crystals, of 252 DENTAL CHEMISTRY. somewhat sweetish, slightly pungent taste, very soluble in water, less so in alcohol, ether, glycerine, and vaseline, in- soluble in chloroform, and carbon disulphide. It is not so irritating as carbolic acid. It is said to be a disinfect- ant and local anaesthetic. It is used in dentistry as an antiseptic* Strong solutions are caustic, but dilute ones merely astringent. 382. Menthol: this substance is really menthyl alcolwl, QoHjjoO, and is found in peppermint oil. It is a white, crystalline solid of but slight peppermint-oil odor when pure, soluble in alcohol, and in the essential oils. It has been called peppermint camphor, Japanese camphor, peppermint stearescence, and stearoptene of peppermint, but, in constitution, is a monatomic alcohol. // is an anti- septic and local anesthetic. It is used in dentistry as an ob- tunding agent, local anaesthetic, and antiseptic. Care must be taken in applying it, as small doses, taken in- ternally, have been known to produce vomiting. 383. Eucalyptol: C^H^O, liquid, colorless, of aro- matic odor. It is derived from the leaves of Eucalyptus globulus, and is sometimes called eucalyptus oil. It is but slightly soluble in water, but is soluble in alcohol. It is an efficient antiseptic, and is used in dentistry on this ac- count, and as an astringent, styptic, and local anesthetic. It has solvent action on guttapcrcha. The purest eucalyp- tol is as clear as water, of specific gravity 0.910 to 0.920 at 6oF., and boils between 338F. and 343. There is in the market an eucalyptus oil which differs from the genuine eucalyptol; 90 per cent, alcohol makes a clear solution of eucalyptol, while the eucalyptus oil is but slightly soluble in it. Alantol: CsoHgX). A liquid stearopten found besides helenin in the root of elecampane. *Said to be a stronger antiseptic than carbolic acid, and not so 1 o'sonous. ORGANIC CHEMISTRY. 253 384. Myrtol: myrtol is obtained from the distillation of the leaves of the myrtle; it is a liquid possessing the characteristic perfume of the plant. It is of less density than water, evaporates at the ordinary temperature, stains paper, but the stains disappear entirely. It has a warm, slightly acrid taste, soon followed by a sensation of fresh- ness. It is said to be an excellent disinfectant and an energetic antiseptic. 385. Safrol: this substance is obtained by fractional distillation from crude oil of camphor. It has a strong sassafras odor and taste, and is used for disguising the taste of other substances. 386. Thymol: formula CioH u O. There are many thy- mols. The one found in essence of wild thyme is used in dentistry, and may be procured by treating the essence with potassium hydrate; insoluble in water, antiseptic. Freely soluble in alcohol. Used in dentistry, combined with glycerine, as an antiseptic. 387. Carbohydrates: these are substances containing six atoms of carbon, or a multiple of six, and twice as many atoms of hydrogen as of oxygen. They closely resemble the alcohols, and may be divided into three classes: saccharoses, glucoses, and amyloses* Of the saccharoses, cane sugar and milk sugar are important. 388. Cane Sugar: saccharose, cane sugar, beet sugar, CigHgzOu, does not occur in the body; white, inodorous, very sweet. Cold water dissolves three times its weight; insoluble in alcohol. Converted by ferments first into mixture of glucose and lasvulose, called invert sugar. ^Saccharin is not a carbohydrate, but the sulphinide of benzoic acid. (See Benzoic Acid). 254 DENTAL CHEMISTRY. Blackens with H 2 SO 4 . (Glucose unites with the acid and does not blacken). Cane sugar occurs in the juices of many plants, fruits, flowers, and in honey. It is found also in the juice of the sugar cane, in sorghum, beet-root, and sugar-maple. The most soluble sugar* as well as the sweetest and most crystallizable. 389. Milk-sugar: lactose, sugar of milk, Saccharum Lactis, CjvHjoOnH^O, one of the constituents of milk of mammals; rarely found in vegetables. To prepare it, coagulate skimmed milk with a little acetic acid, heat, o filter, concentrate filtrate by evaporation, let crystallize, dissolve in boiling water and re-crystallize. Odorless, white, hard, occurs in four-sided, rhombic prisms; taste faintly sweet, gritty between the teeth; soluble in seven parts cold water, one of boiling; insoluble in even 60 per cent, alcohol; not charred by H 2 SO 4 ; not directly fer- mented by yeast, but easily when cheese is added; does not form a syrup with water. Used in tooth powders and in triturating medicines. 390. Glucose: C 6 H 12 O 6 , is raisin sugar and grape sugar; it is also called dextrose and starch sugar. It is found in vegetables, fruits, and honey. Is white, inodorous, and soluble in its own weight of water. Only one third as sweet as cane sugar. Ferments directly with yeast, and when in contact with decaying animal matter. Made on a large scale from corn starch, by boiling with dilute sulphuric acid, neutralizing with lime, draining off clear syrup, evaporating, and allowing to crystallize. Fermented, it decomposes into alcohol and carbonic acid. Valuable re- ducing agent. 391. The amyloses are starch, dextrine, gum, etc. Starch is found in grains of cereals and in potatoes; is food of plants becoming sugar as they ripen. Insoluble *Dissolved in water forms Syrupus Simplex, or simple syrup. ORGANIC CHEMISTRY. 255 in cold water, alcohol, or ether; in boiling water it becomes gelatinous, but does not dissolve ; heated dry it becomes dextrine, which is converted into glucose by action of diastase (a ferment found in cross-spired barley). Dextrine: is an amorphous, yellowish-white, soluble substance; does not give blue coloration with iodine; basis of mucilage. Reduces alkaline copper solutions. The formula for dextrine is probably C 6 H 10 O 5 . That of starch some multiple of C 6 Hi O 5 . 392. Honey: honey is practically a strong solution of dextro-glucose and laevo-glucose in water. Analyses show that the laevulose and dextrose are nearly equal in amount. Fictitious honey is sometimes manufactured from glucose and flavoring materials; the presence of glucose, as an adulteration, is indicated by increased pro- portion of ash, and by the presence of a notable amount of calcium sulphate. Honeys are preparations of medici- nal substances in honey, the clarified article being used. Honey of sodium borate contains a drachm of borax to the ounce of clarified honey. 393. Gums: these bodies are probably carbohydrates. They are a peculiar class of bodies, occurring in the juices of plants. They are entirely non-volatile, of little or no taste, uncrystallizable, and colloidal. They are either soluble in water, or swell up in contact with it. They are not capable of being fermented by yeast and are insoluble in alcohol. 394. Gum Arabic is the dried exudation from the bark of various species of Acacice. Picked Turkey gum is the finest, and occurs in colorless lumps, full of minute cracks. It consists chiefly of calcium arabate, the calcium salt of arabic or gummic acid. It is inodorous, of feeble, slight- ly sweetish taste, and with water^forms a viscid mixture, called a mucilage. The mucilage is used in dentistry as an emollient. 256 DEN.TAL CHEMISTRY. 395. Gum Tragacanth : this is a white, or yellowish substance which is only very slightly soluble in water, and swells up in it. It contains usually about 60 per cent, of a substance which yields pectic acid, also 8 or 10 per cent. of soluble gum, probably arabin, the rest being starch, cellulose, water, etc., etc. 396. Cellulose: Cellulin, lignin, C 6 H 10 O 5 , is an isomer of starch, and constitutes the essential part of the solid framework or cellular tissue of plants. Swedish filter- paper, linen rags, and cotton wool are more or less pure cellulose. Soluble only in a solution of cupric oxide in ammonia. Absorbent cotton: consists essentially of cellulose. 397. Collodion is made by dissolving 4 parts of pyroxy- lin in a mixture of 26 parts alcohol and 70 of ether. Pyroxylin is prepared by steeping cotton in a mixture of nitric and sulphuric acids. Flexible collodion is collodion to which 5 per cent, of tur- pentine and 3 per cent, of castor oil have been added. Cantharidal collodion i-s made from powdered canthar- ides and flexible collodion, with sometimes addition of a little Venice turpentine, to prevent contraction on drying. Iodized collodion is a solution of iodine in collodion, 2O grains to the ounce. lodoform collodion contains I part iodoform to 15 of collodion. Styptic collodion contains 20 per cent, of tannic acid. Collodion is a colorless liquid, of ethereal odor, and very inflammable; exposed to the air it rapidly evaporates, leaving a thin, transparent, strongly contractile film of dinitro-cellulose, which is insoluble in water or in alcohol. It is precipitated by carbolic acid. Collodion is used in dentistry as a local application in alveolar abscesses, in combination with other agents in odontalgia, on cotton as temporary filling, as a styptic, etc., etc. A colored pre- paration of collodion is used to coat the surface of plas- ORGANIC CHEMISTRY. 257 ter models. Collodion, when thickened, may be rendered thinner by dilution with a solution of I part alcohol in 3 parts ether. Cantliaridal collodion is used as a counter-irritant in den- tal periostitis. A German preparation of cantharidal collodion has been proposed by Dieterich to contain in 1,900 parts of collodion 3 parts of cantharidin and 97 of oil of rape. The German blistering collodion is stronger than the U. S. 398. Celluloid: pyroxylin is reduced to a pulp, mixed with camphor, oxide of zinc, and vermilion, subjected to immense pressure, and seasoned. ETHERS, GLUCOSIDES, FATS, WAXES, ALDE- HYDES, KETONES, ETC. 399. Ethers are derived, theoretically, by replacing the hydrogen atoms in water by hy- drocarbon radicals; they are, therefore, oxides. Ethers are either simple or mixed, according as the hydrocarbon radicals are alike or differ- ent; thus common ether is a simple ether, (C 2 H 5 ) 2 O, that is, C 2 H 5 O C 2 H 5 , while methyl-ethylic ether is a mixed ether C 3 H 8 O, that is, CH 3 O C 2 H 5 . Haloid ethers are bromides, chlorides, etc., of the hydrocarbon radicals: thus, hydrobromic ether is C 2 H 5 Br, or ethyl bromide. Compound ethers are salts of the hydrocarbon radicals, as, for example: methyl acetate, CH 3 (C 2 H 3 O 2 .), or CH 3 O C 2 H 3 O. Fats are compound ethers, in which the hydrocarbon radical is glyceryl 258 DENTAL CHEMISTRY. in almost all cases; thus, stearin is stearate of glyceryl, Csf^CwHssOaV 400. Common Ether. Synonyms: ethyl ether, ethyl oxide, vinic ether, sulphuric ether, /Ether, ^Ether Sulphuri- cus. Theoretical constitution: (C 2 H 5 ) 2 O, or ethyl oxide, derived from H 2 O by substituting C 2 H 5 for each atom of hydrogen; contains 4 atoms of carbon, 10 of hydrogen, and I of oxygen in its formula; by weight, 48 parts carbon, 10 of hydrogen, and 16 of oxygen. Molecular weight, 74. Graphic formula, C 2 H 5 O C 2 H 5 . Preparation: sulphuric acid is used to ether- ize alcohol, hence the name sulphuric ether. There is not, however, any sulphuric acid in pure ether. I part of strong sulphuric acid and 6 or 7 of commercial alcohol are heated to 266 R, in a retort, and then alcohol is run in, slowly, by means of a funnel, while the temperature is kept between 266 F. and 284, and the mixture distilled. The liquid resulting from the distillation contains on its surface crude ether, which, purified by washing, dried, and redistilled, is ready for the market. The reactions are as follows: First stage, QH.HO + H 2 S0 4 = (C 2 H 5 )HS0 4 + H 2 O. Alcohol sulphuric ethyl sulphuric water, acid. acid. ORGANIC CHEMISTRY. 259 Second stage, C 2 H 5 HS0 4 + C 2 H 6 HO - (C 2 H 5 ) 2 + H 2 SO 4 Ethyl sulphuric alcohol ether sulphuric acid acid. The second equation shows that the acid is obtained again, hence a small quantity of sul- phuric acid can be used to convert considerable alcohol into ether. Ether for anaesthetic pur- poses is further purified by shaking- with water and contact with lime and chloride of lime. Properties: pure ether is a mobile, very vola- tile liquid, colorless, limpid, and inflammable, of sweetish, characteristic odor* and burning taste. It should be kept in bottles closed by ground-glass stoppers, as it readily evaporates. It is soluble in 10 volumes of water, and in alcohol in all proportions. When pure it dis- solves oils, resins, many organic bodies, iodine, bromine, sulphur, phosphorus, and mercuric chloride. Ether should not only be kept from the air, but also from the light. Its vapor is 2,^/2 times as heavy as air, therefore flows, and will inflame with explosion from contiguous flame. The sp. gr. of ether is variously given as 0.720, 0.736, and 0.713; that of stronger ether, Either Fortior, is 0.728. The latter contains about 94 per cent, of pure ether, and 6 percent, of alcohol. Ether used for anaesthetic purposes should not effect blue litmus, should leave no *Called ethereal odor. 260 DENTAL CHEMISTRY. residue when evaporated on a watch glass, and should not impart a blue color to ignited copper sulphate. Samples should be tested before being- used. 401. Use in dentistry: ether is used as an anaesthetic, both by inhalation and locally ; also as an anodyne, and in various conditions, as aphthae, etc. // is useful as a solvent. Toxicology: the treatment, in cases where dangerous symptoms appear, is to cease ad- ministering the ether at once, and, if the breath- ing begins to fail, to pull out the tongue, to ap- ply electricity, the poles being placed over the phrenic nerves (on a line with the 4th cervical vertebra) and to try artificial respiration. In administering ether, the breathing should be watched. 402. Ethyl bromide. Synonyms; bromide of ethyl, hydrobromic ether, Ethyl Bromidum, Theoretical constitution: C 2 H 5 Br, bromide of the radi- cal ethyl, one molecule of ethyl and one atom of bro- mine, or two atoms of carbon, five of hydrogen, and one of bromine in its molecule. It is one of the so-called haloid ethers (see Ethers). Preparation, properties, etc.: ethyl bromide is obtained by distilling potassium bromide with alcohol, water, and sulphuric acid. The resulting product is redistilled with calcium chloride, Ethyl bromide is a very volatile, colorless liquid, of ethereal odor, strong, sweetish, pungent taste. It is heavier than water, and but slightly soluble in it; soluble ORGANIC CHEMISTRY. 261 in ether and in alcohol. It often contains bromoform as an impurity, and, if it acquires a disagreeable odor, be- comes brown on standing, or is inflammable or explosive, it is not fit for use. Use in dentistry: ethyl bromide is an ancesthetic, producing complete anaesthesia in a few minutes, followed by re- covery of consciousness in from one to two minutes after it is withdrawn. Toxicology: several deaths from its use as an anaes- thetic were reported some time ago, and its use was dis- continued. But of late, according to Asch of Berlin, the discovery has been made that the toxic effects were due to sulphur and arsenic impurities consequent on the old method of preparation. It is said that C. P. ethyl bro- mide, made by the modern method described above, has been used repeatedly without deleterious results. 403. Compound ethers. Ethyl nitrite, C 2 H B NO 8 , diluted with alcohol forms "sweet spirits of nitre." Amyl nitrite: this substance is the nitrite of the radi- cal amyl; its formula is C 5 H U NO 2 .* Molecular weight, 117. It is made by heating equal volumes of purified amyl alcohol (fusel oil) and nitric acid, until the mixture boils. It is a yellowish, ethereal liquid, having the odor of over-ripe pears, and an aromatic taste. Its specific gravity is from 0.877 to 0.900. It is volatile and inflammable, soluble in alcohol; solution rapidly deteriorates. Several samp- les of amyl nitrite examined by Allen contained only 80 per cent, of real amyl nitrite. It is used in dentistry as an antidote for chloroform, being administered by inhala- tion, and for relief of neuralgia, epileptic attacks during extraction of teeth, etc., etc. Toxicology: in administering amyl nitrite by inhalation, *It may be obtained put up in glass bulbs holding a drop or two. The latter are to be crushed before inhalation. 262 DENTAL CHEMISTRY. care should be observed. The handkerchief should be withdrawn when the face becomes flushed and the heart excited. 404. Grlucosides: these bodies are regarded as ethers of glucose.* Those used in dentistry are tannin and gallic acid. Tannin, tannic acid, gallotannic acid, is Ci 4 HmO 9 . The tannic acid used in dentistry is obtained from powdered galls. It forms light-yellow, amorphous scales, of faint char- acteristic odor, and strongly astringent taste, easily soluble in water and in dilute acids. Tannin unites with albumin, gelatin, etc., form- ing insoluble compounds. In the blood, it absorbs oxygen and becomes gallic acid. It is an active astringent and styptic, and is a valuable agent in dentistry as a local appli- cation in many disorders, as mercurial stom- atitis, hemorrhage after extraction, etc. It is sometimes used dissolved in glycerine, Glycer- itum Acidi Tannici, and also in the prepara- tion known as styptic colloid, which is a satur- ated solution of tannin and gun cotton. 405. Gallic acid, HC 7 H 5 O 5 , or C 6 H 2 (HO) 3 CO 2 H, is ob- tained by exposing moistened galls to the air for six weeks. A peculiar kind of fermentation takes place, and * Because when treated by ferments or dilute acids they are de- composed and yield glucose among other products. They occur in plants, andare often accompanied by an albuminoid substance which may act as a ferment and turn them into glucose. ORGANIC CHEMISTRY. 2G3 the tannic acid of the galls is converted into gallic acid. Gallic acid is a white solid, occurring in long, silky needles. It has an astringent, slightly acid taste, and is acid in reaction. It is not readily soluble in cold water; it is soluble in three parts of boiling water, in alcohol, and in ether. It is used in dentistry in form of a gargle, as astringent, antiseptic, and styptic. 406. Fats and fixed oils: these substances, as has been stated before, are compound ethers of glyceryl. Some are liquid and others solid. Stearin is the constituent of the more solid fatst,palmitin of mutton, lard, and human fat; olein is the fluid constituent of fats and oils; fats treated with hot alkalies or with superheated steam, are saponified, as the term is, stearates, palmitates, and oleates of the alkalies being formed (soap) and gly- cerine. 407. Cacao butter is a concrete oil from the kernels of the fruit of Theobroma Cacao. 408. Waxes belong to the spermaceti group of oils. They do not yield glycerine when saponified. 409. Bees-wax is the material of which the honey- comb of bees is composed. It occurs as a compact, tough, solid substance of a yellow or brown color, almost tasteless, but of characteristic, aromatic odor. It is not greasy to the touch. On exposure to air in thin slices, it becomes decolorized. It may be bleached by nitric acid. It is insoluble in water, but soluble in the fixed oils, oil of turpentine, benzol, ether, and carbon disulphide. It is difficultly soluble in alcohol. Its specific gravity is from 0.959 to 0.969. 410. The yellow wax is Cera Flava; bleached, it is called Cera Alba, or white wax. The best method of bleaching is exposure to moisture and the rays of the sun. A new process is, first, to melt together 8 parts of 264 DENTAL CHEMISTRY. yellow wax and I to \% parts of rectified oil of turpen- tine, and then expose to air, etc. Grain wax may be bleached by dioxide of hydrogen. Other chemicals can not be used as they change its constitution. 411. Croton Oil: this oil belongs to the Castor Oil group of oils, distinguished for their very high specific gravity and viscosity. They are readily soluble in alco- hol, and are strongly purgative. Both castor oil and croton oil are miscible with glacial acetic acid in all pro- portions. In drying character, they resemble the oils of the Cotton Seed Oil group. It produces pustules, when applied to the skin, and is valuable as a counter-irritant. Toxicology: in overdoses it has frequently proved fatal. 412. Chloroform. Synonyms: trichlormethane, dichlor-methyl chloride, formyl terchloride. Theoretical constitution: CHC1 3 , or methane, CH 4 , in which three atoms of hydrogen have been replaced by three of chlorine. Chloroform has, in its molecule, one atom of carbon, one of hydrogen, and three of chlorine; by weight, 12 parts carbon, I of hydrogen, and 106.2 of chlorine. Molecular weight, 119.2. Preparation: commercial chloroform is usu- ally made by the action of bleaching powder on alcohol; in 24 parts of water 6 parts of bleaching powder are dissolved, the mixture strained into a retort, heated to I02F., and one part of strong alcohol added. The mix- ture is then distilled. Bleaching powder is ORGANIC CHEMISTRY. 265 chiefly calcium hypochlorite, which with alco- hol yields on distillation chloroform, calcium formate, calcium chloride, and water, through various intermediate stages. Chloroform for anaesthetic purposes, purified chloroform, U. S. P., is prepared from the commercial by mixing with sulphuric acid, agitating, drawing off the chloroform, treating with sodium carbonate, and distilling over calcium oxide. In a new process for making chloroform, alcohol is said to be dispensed with, and the chloroform made by distillation of wood and subsequent treatment of the distillate. Chlor- oform is also made from chloral hydrate, and by electrolysis, from chlorides of the alkalies in presence of alcohol, aldehyde, or acetone. Properties: chloroform is a mobile, colorless, 'volatile liquid of bland, peculiar, sweetish, ethereal odor, and hot, aromatic, saccharine taste. Specific gravity of the purified is 1.5022, and boils at I42F. The official chloroform of the U. S. Pharmacopoea contains a little alco- hol, and its sp. gr. is 1.488. It is heavier than water and not soluble in it, but is freely soluble in alcohol and ether. // dissolves a large number of substances, among them camphor, fixed and volatile oils, many resins, fats, caout- chouc, sulphur, phosphorus, iodine, bromine, and many alkaloids. 266 DENTAL CHEMISTRY. Purified chloroform should not affect litmus paper, nor color green a mixture of chromic and sulphuric acids. Sulphuric acid should not color it brown, nor should potassium hy- drate. Allowed to evaporate on the hand, no foreign odor should be noticed. It is said not to be inflammable, but is com- bustible burning with a dull, smoky flame on application of a naked flame to it. Spirit of chloroform contains an ounce of chloroform in two ounces of dilute alcohol. Uses in dentistry: as an anaesthetic, both gen- eral and local, though, for the latter purpose, usually combined with other agents; as an anodyne, and antispasmodic. It is also an antiseptic and styptic. Applied to the skin, it acts as an irritant and vesicant, if evaporation is retarded. Toxicology : deaths following administration of chloroform have been quite frequent. Pa- ralysis of the heart, and, in some cases, exclu- sion of air from the lungs are the causes of death. In administering it, some air should be admitted along with it. It should never be administered to persons suffering from diseases of the heart or kidneys. At the slightest symp- tom of heart failure during administration of chloroform, the patient should be placed in a recumbent position, cold affusions applied, and artificial respiration, together with induced ORGANIC CHEMISTRY. 267 electricity, be resorted to. Inhalations of from three to five drops of amyl nitrite have been recommended. 413. lodoform: this substance, CHI 3 , is similar in theoretical constitution to chloro- form, except that it contains iodine instead of chlorine. It may be made by acting" on alco- hol, aldehyde, and many other substances with iodine and potassium carbonate or hy- drate. // is usually prepared by heating to- gether an aqueoits solution of potassium car- bonate, iodine, and alcohol, until the brown color of the iodine has disappeared. It occurs in small, lemon-yellow, htstrous crystals of an odor* not so bad at first, but soon becoming unsuppor table. It melts at 248F., and vola- tilizes gradually at ordinary temperatures. // is nearly insoluble in water and in acids, but soluble in alcohol, ether, chloroform, disulph- ide of carbon, fixed and volatile oils. It is not, however, so easy to dissolve it, as many of the books would lead us to infer. It is neutral in reaction. lodoform is not an escharotic, and is an antiseptic, disinfectant, and anesthetic. It is now made by electrolysis from iodide of potassium dissolved in alcohol, through which a stream of carbonic acid is constantly passed, lodoform is decomposed by sunlight (turning * The odor is called "saffron-like" and is not perceptible in the preparation known as bituminized iodoform. 268 DENTAL CHEMISTRY. violet). It loses 0.016 per cent, an hour, ex- posed in a thin layer to the air. Use in dentistry: it is used as an antiseptic, and anodyne; dissolved in oil of turpentine, it is said to be a germicide. It acts chemically, by allowing" escape of free iodine, and also mechanically, favoring cicatrization. In dent- istry, iodoform is combined with numerous agents, among them eucalyptol, arsenic, crea- sote, carbolic acid, camphor, etc., etc. The odor of iodoform may be disguised by mixing i part of cumarin with 25 of iodoform.* The odor may be removed from the hands, by- washing them in an aqueous solution of tannic acid. A French antiseptic dressing containing iodoform is composed of equal parts of pow- dered iodoform, cinchona, benzoin, and mag nesium carbonate, the latter being saturated with eucalyptol. Acetate of potassium should be given in cases of poisoning. 414. lodol: tetra-iodo-pyrrhol, CJ 4 NH, made from pyrrole, a product of the destructive distillation of pro- teids. Light-yellowish-gray, micro-crystalline powder, odorless, almost tasteless, almost insoluble in water, soluble in three parts alcoholf (by weight), in 2 parts ether, and in 7 parts warm oil. Contains nearly 89 per cent, iodine, and * Oil of sassafras is also said to be useful in disguising the odor. t Alcohol must not be boiled when used as a solvent for fear of decomposing the iodol. ORGANIC CHEMISTRY. 269 used as a substitute for iodoform. Used in dentistry as an antiseptic. lodol wax has been used as a temporary stop- ping. Said not to be so toxic as iodoform. 415. Aldehydes: aldehydes lie midway be- tween alcohols and organic acids; they have two less atoms of Hydrogen than the corres- ponding- alcohol. Faraldehyde (C 2 H 3 HO) 3 or C 6 H 12 O 3 , is used as a sub- stitute for morphine, and is a liquid. 416. Chloral hydrate. Chloral is prepared by passing dry chlorine into abso- lute alcohol, until saturated, then adding sulphuric acid and distilling. The chloral thus obtained is a colorless liquid; if, now, this liquid be treated with a small quantity of water, it becomes a solid, C 2 C1 3 HO.H 2 O, which is the well-known chloral hydrate. The latter is a colorless, transparent, crystalline solid, of aromatic, pungent odor and taste, soluble in water, very soluble in alcohol, ether, glycerine, fixed and volatile oils, neutral in reaction, melt ing at I36.4F., and boiling at 203. It has a bitter, caustic taste; it liquefies when mixed ^with carbolic acid or camphor. It volatilizes slowly at ordinary temperatures. It is decomposed by weak alkalies into chloroform, and a formate of the alkali metal; this change was thought to take place in the blood when chloral was taken internally, but recent investigations fail to support the theory. In preparing chloral, 5 per cent, of ferric chloride is added by some to the alcohol, before the chlorine gas is introduced. Use in dentistry: chloral hydrate is used in dentistry locally, for relief of odontalgia, etc. It is an antiseptic, and local anaesthetic, especially when combined with other agents. Chloral hydrate is familiarly termed "chloral." 270 DENTAL CHEMISTRY. Toxicology: the treatment, in cases of poisoning, con- sists of use of the stomach pump, and maintenance of respiration. 417. Croton-cliloral hydrate is, chemically speaking, butyl-chloral hydrate. Its. formula is C t H 5 Cl 3 O.H 2 O. It is made by passing dry chlorine through aldehyde cooled to I4F. Butyl-chloral is obtained, and, on addition of water, butyl-chloral-hydrate. It occurs in the form of crystalline, micaceous scales, of pungent odor, sparingly soluble in water, readily in alcohol, and in hot water, nearly insoluble in chloroform. 418. Ketones: these substances are con- sequent on the first action of oxidizing; agents on secondary alcohols, just as primary alcohols yield aldehyde when oxidized. Secondary al- cohols contain the group' of atoms CHHO, in- stead of CH 2 HO, which is found in ordinary alcohol. 419. Organic acids and salts. Organic acids may be deemed to be built upon the water type, half the hydrogen, in one or more molecules of water, being replaced by a compound organic radical, always containing oxygen: for example, water is H 2 O or H O H; replace half the hydrogen, that is, one atom, by C 2 H 3 O, a compound organic radical containing oxygen, and we have H O C 2 H 3 O or HC 2 H 3 O 2 , acetic acid. It will be noticed that this formula is the same as that of ethyl aldehyde, phis one atom of oxygen. Alcohol, aldehyde, and acetic acid resemble one an- ORGANIC CHEMISTRY. 271 other in a certain way. Thus, the formula for ethyl alcohol is C 2 H 6 O, that of aldehyde, C 2 H 4 O or alcohol minus two atoms of hydrogen and that of acetic acid, C 2 H 4 O 2 , or aldehyde plus one atom of oxygen. 420. Acetic acid: its formula is C 2 H 4 O 2 , or C 2 H 3 O O H. It is a monobasic acid, like nitric, hence its formula is conveniently written, HC 2 H 3 O 2 , and the radical C 2 H 3 O 2 occurs in all acetates, the H (one atom) being replaced by some positive element, as K, Na, Pb, etc. Acetic acid is the result of the fermentation of saccharine fluids, after alcoholic fermentation is over. It is prepared, how- ever, from the residuary liquid obtained in the distillation of wood. Acidum Aceticum, U. S. P., HC,H 3 O 2 = 60, is a watery solution, composed of 36 per cent of hydrogen acetate, and 64 of water. It is a clear, colorless liquid, of a dis- tinctly vinegar-like odor, a purely acid taste, and a strongly acid reaction. Sp. gr. 1.048 at 59F. Miscible in all pro- portions with water and alcohol, and wholly volatilized by heat. Acidum Aceticum Dilutum has 6 per cent, of ab- solute acetic acid, and a sp. gr. of 1.0083. Acidum Aceti- cum Glaciate, glacial acetic acid, is nearly or quite abso- lute acetic acid: at or below 59F., it is a crystalline solid; at higher temperatures, a colorless liquid. It is very cor- rosive. Acetic acid dissolves resins, camphor, fibrin, and coagu- lated albumin; it precipitates mucin. It blisters the skin and is a corrosive poison: antidotes are alkalies, alkaline carbonates, soap, etc. Glacial acetic acid is used by dentists, externally, as a caustic. 421. Acetates: important acetates are those of ammo- nium, aluminium, and lead. Spirit of Mindererus : ammonium acetate, NH 4 (C 2 H 3 272 DENTAL CHEMISTRY. O 2 ). To make it, saturate dilute acetic acid with ammo- nium carbonate and filter. Colorless, pungent, odorless liquid; should be freshly made. Used in dentistry as a lotion, and internally as a refrig- erant. Its formula is usually written NH 4 C 2 H 3 O 2 . It is completely volatilized by heat. 422. Aluminium acetate: a solution of it, known as Liquor Aluminii Acetatis, occurs in pharmacy and is used by dentists as an antiseptic, disinfectant, and deodorizer. It contains from 7> to 8 per cent of basic aluminium acetate. (A1 2 (HO) 2 (C 2 H 3 O 2 ),, 324). 423. Lead acetate is known officially as Plumbi Acetas, Pb (C 2 H 3 O 2 ) 2 , 3H 2 O = 378.5. For pharmaceutical pur- poses it is made from oxide of lead, acetic acid, and water; PbO + 2HC 2 H 3 O 2 + 2H 2 O = Pb(C 2 H 3 O 2 ) 2 3H 2 O Colorless, glistening, transparent crystals, efflorescent, soluble, of sweetish, astringent taste. Aqueous solutions become turbid from presence of carbon dioxide of the air, causing formation of carbonate of lead which is insol- uble. 424. Sub-acetate of lead : the acetate and hydrate, basic acetate, Pb(C 2 H 3 O 2 ) 2 , Pb(HO) 2 . Colorless liquid, more poisonous than the acetate. Precipitated by solu- tions of gum. Used in Goulard's extract, Liquor Plumbi Subacetatis, a 25 per cent, solution of the sub-acetate. 425. Lead water, which is two fluidrachms of Liquor Plumbi Subacetatis in a pint of distilled water, is used in dental practice as a local application. It is known as Liquor Plumbi Subacetatis Dilutus. Compounds of lead are poisonous, but chronic poisoning is more common than acute; in the latter case, emetics should be administered or the stomach pump used, large draughts of milk containing white of egg given, and sul- phate of magnesium dissolved in dilute sulphuric acid. 426. Trichloracetic acid should really be considered ORGANIC CHEMISTRY. 273 under the head of chloral hydrate, for it is formed when the latter is oxidized by nitric acid. It is called also tri- chloroacetic acid. Its formula is HC 4 C1 3 O 2 ; it is a colorless, crystalline solid, soluble in water and in alcohol. It is a caustic and coagulates albumin. It is used in dentistry as a germicide and an antiseptic. According to Dr. Filip- powitch it is a powerful antiseptic even in 0.2 per cent, solutions, while in I per cent, or 2 per cent, solutions it destroys all forms of organic life; in 5 per cent, it does not arrest the growth of yeast, but does that of bacteria and micrococci. 427. Benzoic acid: formula, HC 7 H 6 O 2 . This acid may be obtained from benzoin, naphthalin, toluol, or from the urine of herbivorous animals. It is a solid substance oc- curring in lustrous blades, or needles, but slightly soluble in cold water, soluble in boiling water, more soluble in alcohol and ether. Borax added to it increases its solu- bility in water, as does sodium phosphate also. The acid is monobasic, like nitric acid. Most benzoates are solu- ble. Benzoic acid is an antiseptic, and is used in dentistry as such; also, as a local haemostatic, in combination with powdered alum. It is one of the ingredients of Harris's Gum Wash. A mmoniu m benzoate, NH 4 C 7 H 5 O2 = 139, is the benzoate most used. It occurs in the form of prismatic crystals, colorless, and transparent, or white and granular, soluble in 5 parts of water. It becomes yellow on long exposure to air. Benzoates, like benzoic acid, are antifermentative in action. Ammonium benzoate is administered in cases of phosphatic calculus, which, in time, it dissolves. Lith- ium benzoate has for its formula LiC 7 H 5 O^ = 128.* * A derivative of benzoic acid is the new sweet substance Sac- charin ; a white, crystalline powder, soluble in 250 parts water, easily soluble in alcohol and ether. Said to be 280 times as sweet as cane-sugar. Solubility increased by addition of alkaline solutions. 274 DENTAL CHEMISTRY. 428. Eugenic acid. Synonyms: eugenol, caryophyllic acid, oxidized es- sence of cloves. Theoretical constitution: C 10 H U O 2 . Occurrence: found along with a hydrocarbon in oil of cloves. Preparation: crude oil of cloves treated with potash is distilled, and the residue is subjected to the action of a mineral acid. The substance may also be obtained from cinnamon leaves. Properties: colorless oil of sp. gr., 1.07, of spicy, burning taste, soluble in water and in alcohol. Reddens litmus, and coagulates albumin. On contact with air, becomes darker and resinous. Use in dentistry: as a germicide, obtunding agent, etc., etc. 429. Hydrocyanic acid: Acidum Hydrocyanicum, HCN or HCy, cyanhydric acid. Exists ready formed in juice of the bitter cassava; may be obtained from bitter almonds, kernels of plums and peaches, apple seeds, cherry laurel, etc.; clear, colorless, volatile liquid, of peculiar, pungent odor. The official acid contains about 2 per cent, of the anhydrous acid. Its compounds are cyanides, or cyanurets, as formerly termed. 430. Mercuric cyanide, HgCy or HgCN, has already been considered. 431. Oleic acid: formula C I8 H 31 O 2> or HC 18 H33O 2 , or C^HsgCOOH, is of the fatty acid series, like acetic acid. It is found, in combination with glyceryl, in most animal fats and non-drying vegetable oils. Its salts are called olcatcs, and are definite chemical compounds. Metallic oleates seem to exert an antiseptic action, not only on the fats with which they may be combined, but also on discharges from suppurating surfaces, etc., etc. The pure oleic acid is free from unpleasant odor or ran- ORGANIC CHEMISTRY. 275 cidity. Oleates of the alkaloids are prepared by dis- solving the alkaloid in oleic acid. Important oleates are those of aluminium, arsenic, bismuth, cadmium, copper, iron, lead, mercury, silver, tin, zinc, and iron. 432. Mercuric oleate is of stable composition, as now prepared, and has all the therapeutic effects of mercury. It does not become rancid nor stain the linen. Its formula is Hg(C 18 H33O 2 ) 2 = 762. It is made from yellow mercuric oxide. The official U. S. P. oleate is a liquid. PERCENTAGE OF METAL IN THE METALLIC OLEATES. 100 parts of oleate cf correspond to Oxide % Aluminium A1 2 O 3 5.86 Arsenic As 2 O s 21.55 Bismuth Bi 2 O 3 22.22 Copper CuO 12.67 Iron (ferric) Fe 2 O 3 8.89 Lead PbO 28.95 Mercury (precip.) Hg 28.32 Silver Ag 2 O 29.77 Zinc ZnO 12.90 433. Oxalic acid: H 8 (C S O 4 ), 2H 2 O = 126. Occurs in combination in Oxalis and in Rhubarb. Made from sawdust by action of caustic alkali. Color- less, transparent crystals, readily soluble, odorless, of intensely acid taste. Dangerous poison. The treatment, in cases of poisoning, consists in giving lime, chalk, or magnesia in very small quantities of milk, and subsequently emetics if there is no vomiting. 434. The salts of oxalic acid are oxalates, and con- tain C 2 O 4 ; the acid is dibasic, hence calcium oxalate would have CaC 2 O 4 for its formula; potassium oxalate, K 2 C S O 4) etc., etc. 435. Cerium oxalate is Ce 2 (C 2 O 4 ) 3 .9H 2 O = 708. 436. Lactic acid: this acid is of importance 276 DENTAL CHEMISTRY. to the dental student in view of the experi- ments of Miller, Black, Magitot, and others in regard to caries. Theoretical constitution: C 3 H 6 O 3 CH 3 I graphically CH O H CO.O-H. Composed of 3 atoms of carbon, 6 of hydro- gen, and 3 of oxygen; by weight 36 parts of carbon, 6 of hydrogen, and 48 of oxygen. Molecular weight, 90. Formula usually writ- ten HC 3 H 5 O 3 , to denote the monobasic char- acter of the acid. Occurrence and preparation: lactic acid is the acid of sour cabbage and of sour milk. It is produced in these substances by the action of a special ferment called lactic ferment. It is found in several parts of the human body, namely, in the urine, intestinal juices, and in the gastric juice. It exists in many products after fermentation, as in beet juice, various vegetables, nux vomica. 437. It, or isomeric modifications of it, oc- curs in the fluids which permeate muscular tissues. A variety called sarco-lactic acid is found in the muscles and also in the hepatic cells. Abnormally, lactic acid is found in the blood, particularly in leukaemia, pyaemia, etc.; ORGANIC CHEMISTRY. 277 it may be found in purulent discharges, in the saliva in diabetes, and in the urine, especially after phosphorus poisoning-, in acute atrophy of the liver, leukaemia, trichinosis, and occal sionally in rickets and osteomalacia. 438. On a large scale lactic acid is prepared by the lactic fermentation, so called, of cane sugar and glucose. Flour is treated with dilute sulphuric acid and its starch thus converted into glucose; the free sulphuric acid is neutralized with milk of lime and sour milk is added, which gives rise to a fermentation in the sugars. This fermentation is checked before the so-called butyric fer- mentation sets in, by heating to the boiling point. Cal- cium lactate is formed, and the hot solution, after filtra- tion, is evaporated down and allowed to crystallize. From calciumlactate, lactic acid is obtained by saturation with sulphuric acid. In the human body, lactic acid is possibly a derivative of sugar: C 6 H 12 6 2(C 3 H 6 3 ) Glucose. Lactic acid. It is decomposed in the system into carbonic acid and water, perhaps splitting up first into butyric acid, carbonic acid, and hydrogen. The lactic acid found in sour milk is produced by the transformation of the sugar of milk into lactic acid, by the influence of decomposing casein: C I2 H 22 O U + H 2 O 4HC 3 H 5 O 3 . Milk-sugar. Water. Properties: the official U. S. P. lactic acid is a color- less, syrupy, odorless, strongly acid liquid containing 75 per cent, of lactic acid. Sp. gr., 1.212. It mixes readily with water, alcohol, and ether; is nearly insoluble in chloroform. 278 DENTAL CHEMISTRY. Lactic acid possesses the property of dis- solving" calcium phosphate. It has been shown, by Magitot and others, to be capable of decomposing the teeth; sections of dentine, placed by Miller in infected culture fluids, were decomposed by the lactic acid formed. Leber and Rottenstein found that solutions of lactic acid, i part in 100 of water, decalcified the teeth. Miller's experiments tend to show that, during- caries, lactic acid is formed in the teeth and in sufficient amount to destroy the dentine. 439. Lactic acid is a monobasic acid, H(CjH,Oj); its salts are lactates, and are all soluble. Phosphates dis- solved in lactic acid form lacto-phosphates. Calcium lacto- phosphate is made by the action of lactic acid on calcium phosphate. 440. Salicylic acid: formula C 7 H 6 O 3 , or HC 7 H 5 O 3 , or C 6 H 4 (OH)CO 2 H. It is also called oxybenzoic acid. It forms a large percentage of oil of wintergreen, but is pre- pared on a large scale by the action of carbon dioxide on sodium phenate (carbolate). Properties: odorless, white and lustrous masses of fine, small, colorless needles, soluble in boiling water and in alcohol; tasteless at first, but afterwards sweet and astringent, causing acridity of the fauces; soluble in cold water containing three parts of sodium phosphate. Antiseptic and disinfectant. Heated dry in a test tube, sublimes in beautiful needles before melting point is reached, and at higher temperature is dissipated. It is soluble in alcohol, ether, and glycerine. Its salts are salicylates; it is a monobasic acid, H(C 7 H 5 O 3 ), there- ORGANIC CHEMISTRY. 279 fore, sodium salicylate, for example, is NaC 7 H 5 O a . Sali- cylic acid is used in dentistry as an antiseptic, dissolved in water containing a little sodium phosphate or sodium sulphite, or in glycerine, or in ether. It, like many other acids, attacks the teeth slightly, hence is not suitable for mouth washes. It is acid in reaction. 441. Salol: this substance is the phenyl ether of sali- cylic acid, that is, phenyl salicylate, C 6 H 4 OH.COO.C 6 H 6 ; empirically, CgH^HiiO;,, one atom of hydrogen in salicy- lic acid being replaced by the univalent radical C 6 H 5 . It is a white crystalline powder, of mild aromatic odor, in- soluble in water but soluble in alcohol. Used in dentistry as an antiseptic. Betol is the salicylate of beta-naphthol, C 6 H 4 OH.COO. C 10 H 7 . Said to be freer from detrimental properties than alcohol, White, insoluble in water. 442. Sozolic Acid (formerly called Aseptol*): Formula, C 6 H 4 (HO)SO 2 (HO), orthoxy-phenyl-sulphur- ous acid, containing SO 2 in place of carbonyl (CO) of salicylic acid. It is a reddish syrupy liquid, of sp. gr., 1.40, with a feeble and not disagreeable odor. It dissolves in water in all proportions. With ferric chloride it gives the same violet coloration as salicylic acid. Though a decided acid, it has not the corrosive action of phenol. It is said to arrest absolutely every fermentation, diastatic or fungoid, to a much greater degree than phenol and other well-known antiseptics. The advantages of sozolic acid lie chiefly in its great solubility and freedom from odor qualities which, together with the absence of corrosive action, should make it suitable for toilet preparations in many cases. * Aseptol is a 33,^ per cent, solution of the acid. 280 DENTAL CHEMISTRY. It is a valuable antiseptic, according to D. F. Hueppe, and doubtless will partially replace carbolic acid as a dis- infectant and antiseptic. It would seem destined to be of value in dentistry in treatment of fetor of the breath. 443. Tartaric acid: H 2 (QH 4 O 6 ), Acidum Tartaricum. Occurs in grapes, pineapples, tamarinds, and other fruits, as a tartrate. Prepared from crude tartar. Colorless, transparent crystals, soluble in water. Solutions are strongly acid, and deposit fungous growth. In dentistry it is used, combined with "chloride of lime," to bleach discolored teeth. 444. Cream of tartar or potassium Mtartrate: po- tassium acid tartrate, KH(C 4 H 4 O 6 ), made from argols or crude tartar, a deposit on the sides of wine casks; odor- less, of gritty taste, white, almost insoluble in cold water, soluble in from 15 to 20 parts boiling. 445. Bochelle salt: potassium sodium tartrate, KNa (C*H 4 O 6 ) 4H 2 O. Large, transparent, colorless, slightly efflorescent crystals, of mildly saline and bitter taste, readily soluble. 446. Tartar emetic: tartrate of potassium and a radi- cal called stibyl; potassium antimonyl tartrate, 2(KSbO. C 4 H t O 6 ).H 2 O = 664, is prepared by boiling 4 parts of antimonous oxide with 5 parts of cream of tartar in 50 of water. It is soluble in 17 parts of water, but insoluble in alcohol. It is poisonous: treatment should consist in use of stomach pump or emetics, administration of tannin in form of tea, infusion of nut galls, oak bark, etc., and of stimulants. 447. Other organic acids: valeric or valerianic, HC 5 H 9 O 2 ; citric:H 3 C 6 H 5 O 7 .H 2 O. A new disinfectant is oxy- naphthoic acid, alpha: a white, odorless, micro-crystal- line powder, nearly insoluble in water, soluble in alcohol. ORGANIC CHEMISTRY. 281 ALKALOIDS. 448. Alkaloids are artificial, natural, or cadaveric. Artificial alkaloids are the various amines, as methylamine, ethylamine, etc. Methylamine is a gas, ethylamine a liquid, propylamine a volatile oil.* 449. The natural alkaloids: a class of sub- stances chiefly of vegetable origin, often active principles of plants, supposed to be like alka- lies, hence name. Those containing no oxy- gen are volatile; those having oxygen are non- volatile. As a rule, are soluble in alcohol, ether, chloroform; contain nitrogen, turn plane of polarized ray of light to left (with few exceptions), furnish with platinic chloride, double chlorides; have bitter taste, resemble alkalies in uniting with acids to form salts, of which the sulphates, nitrates, chlorides, and acetates are usually soluble, and the oxalates, tartrates, and tannates usually insoluble; in solution are precipitated by many re-agents, including iodine dissolved in iodide of potas- sium: very poisonous. The alkaloids used in dentistry are for the most part natural alkaloids, as morphine, cocaine, etc., etc. Cadaveric alkaloids, or ptomaines, are those found in putrefying animal or vegetable matter, and, in certain * Many therapeutic agents have been discovered among the amines and their derivatives, e. ?. antifebrin, a derivative of aniline which is itself, phenylamine. 282 DENTAL CHEMISTRY. pathological conditions, in the human body during life. Pysemic fluid yields an alkaloid, which has been named septicine. Most of the natural organic bases or alkaloids resemble the -amines or compound ammonias; an -ainine may be regarded as formed by the replacement of one or more atoms in the ammonia (NH 3 ) molecules by positive or hydrocarbon radicals, thus: N H H N H CH H H ammonia methylamine. Some of the alkaloids are more like ammonium com- pounds than like amines. The molecular structure of the vegetable alkaloids is, in most cases, but very imper- fectly understood. 450. Aconitine: C3oH 47 NO 7 , is the alkaloid of aconite, Aconitum Napellus, occurring as a glacial mass or white powder, crystallizing with difficulty in rhombic plates. It is soluble in 150 parts of water, slightly soluble in am- monia water, soluble in benzol, soluble in 2 parts ether, soluble in 2,y 2 parts chloroform. It has a sharp, pungent taste, and is one of the most powerful poisons known. It is fatal, probably, in doses of ^th grain. Samples of aconitine vary in strength, some being wholly inert, others powerfully poisonous. Morson's and Duquesnel's crystal- ized aconitine have about the same solubility, and are of about the same strength. Duquesnel's is in form of large crystals usually, some weighing i th of a grain. Oleate of aconitine contains usually 2 per cent, of the alka- loid. Aconitine, in dental practice, is administered internally, for neuralgia of "the fifth pair of nerves. The treatment, in cases of poisoning, should consist in administration of emetics, and of stimulants as ammonia, brandy, strong ORGANIC CHEMISTRY. 283 coffee, and tea. Liniments and friction to the limbs and spine should be used, mustard plasters applied to pit of stomach, and slight galvanic shocks through the heart administered. Tincture of aconite is a valuable local application in dentistry, especially when combined with various agents, as iodine, chloroform, etc. Poisoning by tincture of aco- nite is to be treated as above; the chief symptoms are numbness and tingling, great sense of fatigue, muscular weakness, etc., etc. 451. Napelline, an alkaloid obtained by Duquesnel from aconite, is less powerful than aconitine, and has" hypnotic properties. 452. Atropine: CnHasNOa. This alkaloid is from Atropa Belladonna. The sulphate of atropine is used in dentistry. Its formula is (CnH^NOs^HsSC^, and it is made by combining atropine with sulphuric acid and evaporating. [The hydrogen of acids is not replaced by alkaloids, when they combine with the acids; in this re- spect the compounds formed differ from compounds of the alkali metals and acids: thus, while atropine sulphate is (CnH^NOs)?, H 2 SO 4 , potassium sulphate is K 2 SO 4 ]. Atropine sulphate is a white, crystalline powder, or forms small, colorless, silky prisms. It is soluble in 3 parts cold water, and 10 parts, go per cent alcohol. The concentrated solution sJiould be neutral to test paper* It is insoluble in ether, inodorous, of disagreeable, bitter taste, and is an active poison. In dental practice, it is used locally as an obtunding agent, etc., and also intern- ally, for neuralgia, etc. The fatal dose is two grains; the treatment should consist in administration of emetics, and subcutaneous injection of pilocarpine or of morphine. * In order to test atropine sulphate, drop a little of the dry powder on litmus paper, both red and blue, previously moistened with water. It should not affect either paper. 284 DENTAL CHEMISTRY. Dryness of the throat, diplopia, vertigo, and in serious cases, delirium, are among the symptoms of poisoning by this substance. 453. Chinoline or quinoline: C 9 H 7 N. This substance is an artificial alkaloid,! and is not the active principle of any plant. It was first made from coal tar, then from cinchona, but now is made from nitroben- zole, aniline, and glycerine, to which sulphuric acid has been added, the mixture being heated and cooled altern- ately. It is a colorless, oily liquid, of sp. gr. 1.094, and boiling at 460 F. In chemical constitution it may be re- garded as naphthalin, Ci H 8 , in which one CH group is re- placed by N. Chinoline forms crystalline salts with acids. The one used in dentistry is the tartrate, (C 9 H 7 N) 2 H 2 CJI 4 O 6 , theoretically, but the real composition of German chino- line tartrate is said to be 3C 9 H 7 N.4QH 6 O 6 , requiring 60.8 per cent, of tartaric acid. Chinoline tartrate forms (microscopic) columnar crystals; it is soluble in 75 parts of water at 6o.8F., and in 150 parts of 90^ alcohol, and 350 of ether. Its taste is peculiar, somewhat burning, penetrating, and suggesting peppermint. It has a faint odor, slightly suggesting bitter almonds. It is used in dentistry as an antiseptic, usually in 5 per cent, solution. It is sometimes combined with carbolic acid. Its aromatic odor is less pleasant than that of pyridine, which it resembles. Chinoline enters into a definite combination with iodo- form. One part of iodoform, dissolved in ether, is mixed with three of chinoline also dissolved in ether. Salts of chinoline should be kept away from the light. "\ Antipyrine is a derivative of chinoline; and is an antipyretic and anodvne. ORGANIC CHEMISTRY. 285 454. Cannabis Indica products: the tincture of Canna- bis Indica, diluted 3 to 5 times, has been used by A. Aaronson and others, as a local anaesthetic in extracting teeth. 455. Caimabinnm Taimicum or cannabin tannate occurs as an amorphous, yellowish or brownish- gray powder, indifferent toward litmus, having a very faint odor of hemp, and a somewhat bitter, strongly astringent taste. When heated on platinum foil, it swells up and finally leaves minute traces of a white ash. It is almost insoluble in cold water, alcohol or ether, and dis- solves but little on warming; but it is easily soluble in water or alcohol acidulated with hydrochloric acid. 456. Cannabine:* this is the name of an alkaloid re- cently prepared from Cannabis Indica. It appears as a vis- cid, brown substance, transparent in , thin layers, of a strongly aromatic odor and a sharp, bitter, and somewhat scratching taste. It is insoluble in water, easily soluble in alcohol, ether, petroleum ether, chloroform, benzol, disul- phide of carbon, ethereal and fixed oils. The solutions are golden-yellow when highly diluted, brown when con- centrated. When heated on platinum foil it leaves no residue. 457. Cocaine: C 17 H 21 NO 4 . This now famous alkaloid is prepared from ErytJiroxylon Coca, a shrub indigenous to certain regions in South America. It is found chiefly in Peru and Chili, and the alkaloid is extracted from the leaves. The process of extracting cocaine from coca leaves is given in full in Squibb's Ephemeris, Vol. II., No. 7; it is too long for insertion here. Pure cocaine crystallizes in colorless, four or six sided monoclinic prisms, soluble in 704 parts of water at 53.6F., easily soluble in alcohol, and still more so in ether. * The pure alkaloid must be carefully distinguished from the resi- noid called "Cannabin.'' 286 DENTAL CHEMISTRY. Cocaine melts near I97F. Cocaine combines readily with dilute acids, forming easily crystallizable salts, which are more or less sparingly soluble in water, but soluble in alcohol. They are insoluble in ether, of bitter taste, and leave a transient sensation of insensibility upon the tongue. The hydrochlorate, or muriate, of cocaine is the salt which has been most used. The ^jsta///^ hydrochlorate has for its formula, C 17 H 21 NO 4 ,HC1. 2H 2 O, when crystal- lized from aqueous solutions. Dried and rendered anhy- drous, its formula is C 17 H 21 NO 4 ,HCL; crystallized from alcohol (B.P. ), its formula is the same as the latter, for it is anhydrous. Hydrochlorate of cocaine occurs in the form of short, transparent, prismatic crystals, permanent in air. It is sparingly soluble in water, but readily solu- ble in alcohol, ether, and in vaseline. The hydrochlorate is termed hydrochloride by some authors; the hydrogen of the hydrochloric acid is not given off in the combination, as is seen from the formula. 458. Other compounds of cocaine are the hydrobromate, C 17 H 21 NO 4 ,HBr; the citrate, (C 17 H n NO 4 )sH s C,H6O T ; the oleate, (CnHUiNO/jHQgHssOa, containing 5 per cent, of the alkaloid; the salicylate, C 17 H 21 NO 4 , HC 7 H 5 O 3 , the phenate or carbolate*, and the phtalate. Salts of cocaine are used in dentistry as local anaesthetics and ano- dynes, especially in alveolar pyorrhoea, extirpation of pulps of teeth, and that of hypersensitive dentine. They have also been used by injection, for extraction of teeth. Combined with menthol, and dissolved in alcohol, chloro- form, or ethyl bromide, they are used as a lotion in neu- ralgia and odontalgia; for the same purpose, dissolved in oil of cloves. Toxic symptoms have followed injection * The carbolate is a colorless mass of faint odor, very readily solu- ble in alcohol. ORGANIC CHEMISTRY. 287 of 6 drops of a 20 per cent, solution into the gums; re- lieved by inhalation of amyl nitrite, 3 drops at a time, 3 inhalations. The purity of cocaine salts is of the greatest importance. The permanganate test should be used for possible or- ganic impurities.* 459. Morphine: morphine, morphia, C 17 H 19 NO 3 .H 2 O, exists as meconate of morphine in opium, which is the concrete, milky juice exuding on incising the unripe cap- sules of Papaver Somniferttm, or white poppy. On account of the comparative insolubility of morphine, its salts are preferred for use in dentistry. Of these the acetate, hydrochlorate, and sulphate are official. They are all freely soluble in water. 460. Morphine acetate, (C 17 H 19 NO3)HC 2 H 3 O 2 .3H 2 O, oc- curs in the form of a white or yellowish white, amorphous or crystalline powder of bitter taste. Soluble in both alcohol and water. It is known officially as Morphines Acetas. 461. Morphine hydrochlorate, (CnH 19 NO s )HC1.3H 2 O, also known as the hydrochloride or muriate, occurs in the form of snow-white, feathery, flexible, acicular crystals, of bitter taste and silky lustre, wholly soluble in both alco- hol and water. Morphinae Hydrochloras orMurias is the official term. 462. Morphine sulphate j\ (C 17 H 19 NO 3 ) 2 H 2 SO 4 .5H 2 O, oc- * To test the hydrochlorate (muriate) of cocaine, take Ingrains cocaine muriate and dissolve in 80 minims of distilled water; add 2 drops of dilute C. P. sulphuric .acid, then 1 drop of a 1 to 100 solution of potassium permanganate in distilled water. Instant discolora- tion, or in less than one minute, shows presence of organic impurities. The purest is said not to discolor in an hour. Comparative tests, that is of several samples at a time, are desirable. t For hypodermic use, the phtalate of morphine is recommended. It comes in transparent, glassy scales, and is said not to be so liable to decomposition as the sulphate. 288 DENTAL CHEMISTRY. curs in form of crystals like the hydrochlorate, neutral in reaction, odorless, with bitter taste, soluble in both water and alcohol. 463. In dentistry /the salts of morphine, especially the acetate and the hydrochlorate, are used in devitalizing mixtures and as obtunding agents, also for temporary re- lief of odontalgia, usually in combination with carbolic acid, oil of cloves, etc., etc. The acetate is used in nerve paste, rather than the sulphate, which latter is thought more irritating. Morphine is also given internally, in facial neuralgia, etc. The average fatal dose of the salts of morphine is 2. grains. Treatment of poisoning by these agents should consist in the use, by all means, of the stomach pump, washing out the stomach either with an infusion of coffee or green tea, or else with water in which finely powdered charcoal is suspended, using a fresh amount for each injection. If the pump is not used, vomiting should be encouraged, zinc sulphate in 5 grain doses, with fifteen minute intervals, being given, or apo- morphine hydrochlorate su\)CM\.d.neou$>\y , in doses of from 1-15 to 1-5 of a grain. Subsequently, 1 5 drops of tincture-of bel- ladonna, or 1-35 grain of atropine sulphate (subcutaneous- ly ), should be given. In the early stages of poisoning the above mentioned treatment is often all that is necessary. In later stages artificial respiration and use of the battery (Faradic current) are imperative. Enemata of strong coffee may be administered. 464. Quinine; C^H^N-A, + 3 H 2 O. This alkaloid oc- curs in cinchona bark, together with a number of others of which cinchona, quinidine, and cinchonidine are the most important. Quinine ( crystallized ), is a white powder, of bitter taste and alkaline reaction. It is nearly insolu- ble in water. Quinine itself is seldom used. Salts of it are sulphates, hydrochloride, salicylate, tannate, hydro- bromide, valerianate, citrate (of iron and quinine), hypo- ORGANIC CHEMISTRY. 289 phosphite. The sulphate, disulphate, hydrobromide, hy- drochlonde, and valerianate, are official. 465. Quinine Sulphates: there are three of these, of which the diquinic sulphate (C 20 H 24 N 2 O 2 ) 2 .H 2 SO 4 .7H.,O, is the official sulphate. It occurs as long, brilliant needles, efflorescing to a white powder. It is but spar- ingly soluble in water: I in 780 parts; in alcohol, i in 65. It is readily soluble in dilute acids, but nearly insoluble in ether or chloroform. The official bimlphate is obtained by dissolving the sul- phate in dilute sulphuric acid. Its formula is C^H^N-A. H 2 SO 4 .;H 2 0. There is another sulphate, obtained by dissolving qui- nine in excess of dilute sulphuric acid. Its formula is (C 20 H 24 N 2 O 2 )2H 2 SO 4 .7H 2 O. It is not official. There is also a hypophosphite. 466. The salts of quinine are used in dentistry in the treatment of various facial and neuralgic affections and as ingredients of dentifrices. 467. The alkaloids of Nux Vomica: Strychnine, Strychninum, strychnia, C^H^NaO^ Occurs in seed of Strychnos Nux Vomica, or poison-nuttree; also in Strychnos Ignatia, or St. Ignatius bean, found as strychnate or acetate. Brucine is the other alkaloid, and is more soluble than strychnine. The bitter taste of strychnine is perceptible in a solu- tion containing but one part in 1, 000,000. Strychnine sulphate (C 21 H 22 N 2 O 2 ) 2 .H 2 SO 4 .7H 2 O, is official, and readily soluble in water. Salts of strychnine are very poisonous, ^ of a grain having caused death. The treatment, in cases of poisoning, should consist in inhalation of chloro- form, use of emetics, and, if possible, the injection into the stomach and withdrawal therefrom of powdered char- coal. Chloral hydrate and paraldehyde are sometimes 290 DENTAL CHEMISTRY. administered as antidotes, and chloroform given intern- ally. 468. Teratrine: C^H^NOn, is an alkaloid found in l^cratrum sabadilla and in Cevadilla, the seeds of Asagrcea officinalis: also in Veratnim album or white hellebore, and Vcratnim viride, or American hellebore. It occurs as a white, or grayish- white amorphous powder, of acrid taste; it causes violent sneezing, if inhaled. The olcate of vera- trine is official, and is made to contain 2 per cent, of the alkaloid, and also ten per cent. In dental practice, veratrine in form of ointment is used for neuralgia, etc. 469, Other alkaloids: Antipyrine, dimethyloxyquinizine, useful as an adjunct to cocaine in dental anaesthetization. Synthetic alkaloid. Formula, C H H 12 N 2 O. White, crystalline, odorless, bitter tasting powder. Antifcbrin or acetanilide. !CH 5 crystalline, odorless, solid; H slightly soluble in warm water; C 2 H 3 O 2 very soluble in alcohol. Synthetic alkaloid. Alstoninc, the alkaloid of Alstonia constricta. White crystals. Apomorphine, emetic. Caffeine: a new compound is the boro-citrate of caffeine. Cytisine, alkaloid of Cytisus laburnum. Ditaine, C^RaoN-jO,, alkaloid of Dita-bark from Alstoni- ca scholaris. Erythrophleine from Erythrophleum. bark; said to be a local anaesthetic. Ethyl-oxy-Caffeine, C g H 9 (O.C 2 H 5 )N White. Lead chloride, ) Add ammonia abundantly to all three pre- cipitates and shake well: silver is dissolved, a mercurous compound blackened, lead not dis- solved nor blackened. II. If nothing with HC1, add hydric sul- phide: a precipitate maybe: Insoluble in ammonium sulphide. Soluble in ammonium sulphide. Mercuric sulphide. ) ^ Arsenous sulphide, yellow. Bismuth sulphide. > % Antimonous sulphide, orange. Cupric sulphide. ) 3 Stannous sulphide, brown. Cadmium sulphide, yellow. Stannic sulphide, yellow. Auric sulphide, brown. Platinic sulphide, brown. A. In order to ascertain whether the precipitate is soluble or.not in ammonium sulphide, throw on a filter, wash well, wash off precipitate from filter, by means of wash bottle, into a porcelain dish, let settle, pour off supernatant liquid, then add ammonium sulphide and stir well. If insoluble in ammonium sulphide, the original solution contained either lead, mercury(-ic), bismuth, cop- per, or cadmium. Cadmium is easily told by its yellow 358 DENTAL CHEMISTRY. color, a mercuric salt by the change of color, on addition of hydric sulphide (reddish-yellow to black, with a mot- tled appearance). If neither of these be found, take a fresh amount of the original solution, and add ammonium hydrate: if it is copper, a beautiful blue color is seen at once. If none of the above tests are successful, it is probably bismuth, or a dilute solution of lead. To a fresh amount of the original solution, add potassium chromate: a bright yellow precipitate indicates lead. {Dilute solutions of lead may not be precipitated by hydrochloric acid, but yet may yield a slight precipitate of a dark color with hydric sulphide, verified by potas- sium chromate). If no lead be found, take a fresh amount of the original solution, and add hydric sulphide. A black precipitate, insoluble in dilute hydrochloric acid, indicates bismuth. B. If the precipitate is soluble in ammonium sulphide, the color of the precipitate produced by addition of hydric sulphide will serve to distinguish antimony, which yields an orange precipitate in an acid solution. Arsenic and tin (stannic) yield yellow precipitates with hydric sulphide, but the arsenic in acid solutions is distinctly lemon-yellow. If there is any doubt, take some of the original solution and pour it into an apparatus from which hydrogen is being evolved and is burning at the mouth of the delivery tube. If arsenic is present, the flame will now deposit a stain on cold porcelain, soluble in sodium hypochlorite. Tin (stannous), gold, and platinum form brown precipitates, when hydric sulphide is added to solu- tions of their salts. To a fresh amount of the original solution, add stannous chloride: if gold is present, a pur- ple color will be seen; if platinum, a brown; if tin, no change. in. If there has been no precipitate with APPLICATION OF CHEMISTRY TO DENTISTRY. 359 hydrochloric acid and none with hydric sul- phide, take a fresh amount of the original so- lution, add ammonium hydrate, ammonium chloride, and ammonium sulphide: Ammonium hydrate and sulphide precipitate Iron group and earths: Ferrous sulphide, black. Cobaltous sulphide, black. Nickelous sulphide, black. Manganous sulphide, flesh colored. Zinc sulphide, white. Chromic hydrate, green. Aluminium hydrate, white. If the precipitate produced by the ammon- ium sulphide is black, to a fresh amount of the original solution add potassium ferrocyanide: a blue precipitate indicates presence of salt of iron. If the precipitate with ammonium sulphide is white or greenish-white, zinc or aluminium is the metal. Take a fresh amount of the original solution, and cautiously add a small quantity of ammonium hydrate, causing it to trickle down the side of the tube: if the precipitate formed is cleared, on addition of plenty of ammonium hydrate, it is zinc, if not, aluminium. iv. If no precipitate has occurred in i, n, or in, take a fresh sample of the original sol- 360 DENTAL CHEMISTRY. ution, and add ammonium hydrate, ammonium chloride, and ammonium carbonate: Ammonium carbonate precipitates Alkaline earths: Calcium carbonate, ) Barium carbonate, [ White. Strontium carbonate. ) If ammonium carbonate produce a white precipitate, add to the original solution potas- sium chromate: a precipitate of yellow color indicates barium, rather than calcium. If there is no precipitate with potassium chro- mate, but a white one with ammonium oxalate insoluble in acetic acid, but soluble in nitric, it \s calcium, rather than barium. Calcium, bar- ium, and strontium are readily identified by flame reactions. In solution are left: alkalies and magnes- ium : Magnesium. Potassium. Sodium. Lithium. Ammonium. Magnesium salts are recognized by yielding a white precipitate with sodium phosphate, after addition of ammonium chloride and hydrate: the precipitate is ammonio-magne- sium phosphate, readily soluble in acetic acid. Ammonium salts do not answer to any of APPLICATION OF CHEMISTRY TO DENTISTRY. 361 the preceding tests, but, if heated with potas- sium hydrate, the odor of ammonia is notice- able and fumes are seen, if a rod, moistened in hydrochloric acid, be held at the mouth of the tube. Sodium and potassium are recognized by flame reactions. (See Section 542, in). 362 DENTAL CHEMISTRY. CHAPTER VIII. LABORATORY WORK CONTINUED CHEMICAL WORK IN THE DENTAL LABORATORY : REFINING GOLD, TESTING AMALGAMS, MANIPULATION OF VULCANITE, COMPOUNDING RUBBER, ETC., ETC. 550. Refining Gold: the separation of for- eign metals from gold is a matter of great im- portance to the dentist, as can be inferred from page 169, on which the effects of the different metals on gold are discussed. Metals may be separated from gold in two ways, by the "dry way" and the "wet way." The object of the " dry method," or roasting, is to convert the metals into oxides, chlorides, or sulphides. 1. Plate-scrap or clippings, and plate-filings; these need usually only to be remelted, if of suitable fineness originally. 2. Mixed filings, and fragments containing solder and platinum; these should be either roasted, or reduced to gold by the " wet way." 3. Sweepings: these should be first well washed, then either mixed with class second, or separately refined. A good method is to fuse 8 parts of sweepings with 4 of APPLICATION OF CHEMISTRY TO DENTISTRY. 363 common salt, 4 of impure potassium carbonate, I of potas- sium bitartrate, and one-half of potassium nitrate, in a crucible. 551. Separation of foreign metals from gold: the most troublesome constituents of gold alloys are tin, lead, zinc, iron, antimony, bismuth, etc., etc. Most of these are oxidiza- ble, hence roasting- with nitre is usually suffi- cient, but tin alloys may better be roasted with mercuric chloride, and if the alloy contain a number of the different metals, sulphide of an- timony should be used. Richardson recommends the following meth- od : 1. Remove all traces of iron or steel by passing a magnet repeatedly through them.* 2. Place the fragments and filings in a clean crucible, lined on the inside with borax, and covered either with a piece of fire-clay slab, or broken crucible. 3. Place the crucible in a furnace, on a bed composed of mixed charcoal and coke. 4. Add small bits of borax and when the metallic mass is fluid, add the potassium nitrate (or whatever refining agent is used) in small quantities from time to time, and continue the roasting from half an hour to an hour, accord- ing to the coarseness of the alloy. Roasting with nitre is usually sufficient, but * Gold scrap sometimes contains traces of steel that should be re- moved by treatment in the " wet way." 364 DENTAL CHEMISTRY. sometimes effects partial separation only. In such a case proceed as follows : 1. Remove crucible from the fire, after roasting- with nitre, and let cool gradually. 2. Break the crucible, remove the button of gold, separate from slag by use of hammer, put into a new crucible, and melt again. 3. Add any particular agent capable of uniting with any particular base metal known to be present; or, try, first, one refining agent then another, until sufficient separation is effected. 4. Pour the melted metals into previously warmed and slightly oiled ingot moulds. 5. Hammer, anneal, and roll the ingot, and if still brittle, melt again with mercuric chlor- ide. Another method, of advantage in a greatly impoverished alloy, is the following: 1. Melt the alloy in a larg-e crucible, adding small quantities of native antimony sulphide, until three or four times the weight of the alloy has been reached. 2. A lead-colored alloy of gold and anti- mony is formed; place it in a clean crucible, melt, and blow a current of air, by means of a bellows, over its surface. 3. Blow gently at first; a current strong enough to produce visible fumes is all that is necessary. When the fumes cease, increase APPLICATION OF CHEMISTRY TO DENTISTRY. 365 the heat, and before pouring; out the gold throw a forcible current of air on the surface. In case the alloy be found now malleable, but stiff or elastic and of dull color, platinum is probably present and must be removed by the "wet method," which, in general, must be used when it is desired to reduce the alloy to pure gold, as is the case when the gold to be refined consists of very coarse filings, frag- ments of plates containing" large quantities of solder, linings with platinum pins attached, particles of base metals, etc., etc. Proceed as follows by the method of Watt:* 1. Dissolve the alloy in aqua regia, using four parts of hydrochloric to one of nitric, C. P. acids being used. The chloride of silver is found as a grayish-white powder at the bottom of the vessel. Let settle, and pour off super- natant liquid. 2. Add gradually to the liquid poured off a clear, filtered solution of ferrous sulphate in distilled water. Gold is precipitated as a brown powder. 3. Let settle, filter, wash off from the filter paper, digest in dilute sulphuric acid, filter again, wash well, and the result is pure gold. 552. .To determine the carat of an alloy. Multiply 24 by the weight of gold in the alloyed mass, and divide product by weight of the mass. Take, for ex- * Quoted by Richardson. 366 DENTAL CHEMISTRY. ample, a solder composed of 6 parts gold, and 3 of other ingredients: the weight of the gold is represented by 6, the total weight 9 /. 24 X 6 -j- 9 = 16. The alloy is, then, 16 carats fine. When now the gold is not pure, attention should be paid to the number of carats, and deduction made accordingly. Suppose a solder contain 48 parts of 22 carat gold, and 28 parts of other constituents; here the true weight of the gold is not 48, but 44. (22 carat gold is one-twelfth alloy; one-twelfth of 48 is 4 and 48 4 = 44)- 553. To reduce gold to a required carat: multiply 24 by the weight of pure gold used, and divide the product by the required carat. The quotient is the weight of the mass when reduced, from which subtract the weight of the gold used, and the remainder is the weight of the alloy to be added. For example, reduce 10 ounces of pure gold to 18 carats: 24 X 10 -^ 18 10 = 3.3 -f ounces of alloy to be added. If the gold is not pure, allowance must, of course, be made by subtracting as in the previous rule. 554. To raise gold from lower to higher carat: Multiply the weight of the alloyed gold used, by the num- ber representing the proportion of alloy in the given carat, and divide the product by that number representing the proportion of alloy in the required carat; the quotient is the weight of the mass, when reduced to the required carat by adding fine gold. For example, suppose it is required to raise 16 carat gold to 18 carats: in 16 carat gold there is 24 16, or 8, alloy; in 18 carat gold there is 24 18, or 6, alloy. The example, therefore, becomes i x 8 -h 6 = i#; that is, add ^ of a pennyweight of pure gold to the I penny- weight of 16 carat gold, in order to obtain 18 carat gold. If, now, instead of adding pure gold it be desired to add gold of some particular carat, it is merely necessary to subtract the numbers, as 16 and 18 above, from the carat instead of from 24. The example above would then APPLICATION OF CHEMISTRY TO DENTISTRY. 367 become, if 22 carat gold were to be added, i X 6 -=- 4 = \y 2 , that is to each pennyweight of 16 carat gold, add ^ pennyweight of 22 carat gold. 555. Methods of preparing dental amalgam alloys. Take a Hessian or sand crucible, fuse in it enough borax to fill the crucible at least one-third full, melt the tin in it over the usual dental or smelting forge-fire and, after it is melted, add the granulated silver, which, pre- ferably, should have been heated to a low redness. The silver soon fuses in the molten tin and after thoroughly stirring with an iron rod or clay pipe-stem of small size, the copper, in form of small pieces of wire, should be added. After it has melted, and the mixture has been stirred, the gold is added, melted, and all is thoroughly stirred. After fusion and mixing is complete, quickly pour the fused mass into a broad, open, flat, shallow receptacle of iron or soap stone, and let cool. (Flagg). According to Flagg, very slow cooling is to be avoided, as it gives rise to almost complete separation of the silver from the tin, or in other words, the cohesion of like mole- cules overcomes the adhesion of unlike ones. The end sought for is to fix the molecules, as much as possible, in the position into which they are. driven by the heat. Prompt cooling secures the greatest uniformity of distri- bution to components. (Flagg). Essig prefers to melt the platinum and silver together first, in case platinum is used, so that oxidation of the tin may not take place at the instant of union with the plati- num. After the platinum and silver have been melted, the tin and gold are to be added. Borax is to be fused in the crucible first and, lastly, a layer of broken charcoal should be placed over the mass before the heating. 556 Alloys and amalgams: tests: the tests by which good amalgam alloys are recognized are partly chemical, partly mechanical. The latter will not be considered in this work. The chemical tests include the quality of the 368 DENTAL CHEMISTRY. mercury. Pure mercury, practically free from metallic admixtures, should be used. 557. Mercury may be freed from mechanical impuri- ties by filtering it through a cone of paper, round the apex of which a few pinholes have been made. Lead may be removed from it by exposing the mercury in a thin layer to the action of nitric acid, diluted with two meas- ures of water, which should cover its surface and be allowed to remain in contact with it for a day or two, with occasional stirring. Wash well with water, dry first with blotting paper, then by gently heating. For effect of sulphuretted hydrogen on alloys, see Sec- tion 530, 31. Use a weak solution to note gradual discol- oration. 558. In testing an alloy for constituent metals, first make a preliminary examination as follows: into a test tube drop some of the metal or alloy in form of clippings, or coarse powder, then pour in some C. P. nitric acid; convenient proportions are a few grains of the metal to a drachm or two of the acid; warm over an alcohol flame, being- careful not to let the acid boil over out of the test-tube, as it is very corrosive and will burn hands, clothing, etc. Of the commoner metals, copper, silver, and zinc will be dissolved. If the copper is in any noticeable quantity, the solution may ac- quire a green or blue color. Tin, gold, anti- mony, and platinum are not dissolved, though traces of the last two may go into solution. 559. Short method of qualitative analysis of amal- gam alloys: according to Eckfeldt and Dubois,* an idea * Quoted by Flagg. APPLICATION OF CHEMISTRY TO DENTISTRY. 369 may be had of the presence of gold and platinum from the action of the tin, which is not dissolved; but, after the action of the acid is over, shows itself as a whitish pre- cipitate, colored from light to deep purple, if gold be present, or dirty-blackish color, \iplatinum be present with or without gold. After some idea is thus gained, take more of the metal or alloy, say 20 grains, and dissolve in half an ounce of acid, using a beaker. It is advisable to use what is sold as C. P. nitric acid, strong. The beaker should not be brought into contact with the naked flame in warming; it may be passed to and fro through the flame, or warmed by dipping into boiling water. After the action is over, evaporate to dryness in a porcelain dish over the water bath, a copper vessel filled with water under which is the alcohol flame. The whole should be under a "hood" for carrying off the vapors, or in a well-vent- ilated room. The fumes of the nitric acid are very irri- tating, and should not be breathed. ( i.)~ After the nitric acid mixture has well evaporated, which will take some little time over the water-bath, add distilled water, stir well, and filter. [ Previous work has revealed the presence or absence of gold, platinum, and tin; there remain silver, copper, cadmium, and zinc to be looked for]. (n.) After filtering, add some dilute hydrochloric acid a few drops of acid in a test-tube half full of water will be enough and, \tsilver\s plenty, a white, curdy pre- cipitate will be formed. (in.) Filter again, and to a little of the filtrate (liquid which goes through the paper) apart from the rest, add a few drops of ammonia water (made by mixing one vol- ume of stronger ammonia water with three volumes of dis- tilled water); a blue color indicates copper. (iv.) To the rest of the filtrate add sulphuretted hydrogen. After the sulphuretted hydrogen water has been added, a black precipitate of copper sulphide will 370 DENTAL CHEMISTRY. result, unless modified in color by a large percentage of cadmium. (v. ) Filter, saving the filtrate, wash the precipitate off the filter paper into a porcelain dish, using the wash bottle (a flask with a perforated cork having two bent glass tubes passing down into the flask; blowing into one tube will force water out through the other in a fine stream). Boil the precipitate in the porcelain dish with sulphuric acid diluted with water (one part of acid, added very slowly and with constant stirring, to four parts of water, well mixed, allowed to stand 24 hours, and decanted). (vi.) Filter, and add sulphuretted hydrogen water to the filtrate, and then a few drops of ammonia; a bright yellow precipitate will indicate cadmium. Suppose now that when testing for copper as above (in.), no blue color appeared with ammonia, then test directly for cadmium, as in (iv), which, if present, will appear as a yellowish precipitate, on addition of the sulphuretted hydrogen; (brownish-yellow indicates that silver has not been com- pletely removed by precipitation with HC1). (vn.) Go back now to the filtrate saved in (v) and boil it down until nearly dry to expel sulphuretted hydro- gen, then add a little pure water, and solution of sodium carbonate until neutral (shown by dipping a piece of red and a piece of blue litmus paper into the mixture which, when neutral, will not change the color of either paper). A white precipitate indicates presence of zinc. The above described process will enable the beginner to test the various dental amalgam alloys for the presence of those metals usually found in them. The detection of gold, platinum, copper, cadmium, and zinc is of importance, for all the alloys contain silver and tin. It is desirable to procure a sulphuretted hydrogen apparatus, such as a Kip generator, and some Woulfe bottles; pass the gas gene- rated through a Woulfe bottle, containing a little water, * APPLICATION OF CHEiMlSTRY TO DENTISTRY. 871 so as to wash it, then directly into the solution to be tested.* 560. Short method of quantitative analysis of the more common amalgam alloys. 1. Estimate the mercury of an old amalgam, for ex- ampleby weighing, heating to redness, weighing again. The loss in weight indicates the weight of mercury which was present. 2. Estimate the tin by weighing, heating to bright red- ness with borax, adding potassium nitrate in small quan- tity, cooling, collecting button and globules, weighing again. The loss in weight indicates the weight of the tin. 3. Estimate th'e silver by rolling out the button (ob- tained by procedure as in 2) into a thin ribbon, boil in a platinum or glass vessel with at least two or three times its weight of concentrated sulphuric acid. Continue boil- ing until the acid no longer attacks the metal, let settle, pour off supernatant liquid, save the residue. Precipi- tate silver from the poured-off liquid, by dipping plates of copper into it. Collect the silver, wash well, heat, weigh. 4. Go back to residue obtained in 3, wash well, dis- solve in aqua regia, drive off acid by evaporation, dissolve in a large quantity of distilled water, add oxalic acid, the gold is thrown down, let settle, pour off supernatant liquid and save it. Collect gold, wash, dry, heat to redness, weigh. 5. To the supernatant liquid obtained in 4, add ammo- nium chloride as long as there is any precipitate. Let * To detect mercury in form of vapor given off from amalgam alloys, Haines and Talbot have used ammonio-silver nitrate, a drop or two of which, on c hemically pure filter-paper, they find will detect, by discoloration, exceedingly small quantities of mercury. Whether fillings which respond to this test are hurtful to the patient or not, must be decided by clinical experience. 372 DENTAL CHEMISTRY. precipitate settle, filter, wash, dry, and weigh the precipi- tate. Every 100 parts contains 44.28 of platinum. (Essig). 6. Estimate the percentage of each metal present by dividing the \veight of the metal found by the weight of the amalgam in the beginning, before anything was done to it. 561. Tests for cements: tests should be made both of the liquid and of the powder. The oxyphosphate cements consist usually of glacial phosphoric acid and oxide of zinc. Take the reaction of the liquid with blue litmus to show that it is acid. Pour a little of the liquid into a test tube, and holding the latter inclined, let an aqueous solution of a little egg-albumin gradually trickle down the side of the tube into the acid. If a zone of whitish turbid- ity is noticed at the juncture of the two liquids, it is* glacial phosphoric acid, rather than the common acid. To prove that it is phosphoric acid rather than any other, as for example, lactic or hydrochloric, add to a little of it, solution of silver nitrate, and a white precipitate is pro- duced; this does not tell it from hydrochloric, but further add barium chloride solution, and if glacial phosphoric acid is the one, a white precipitate will be produced. The tests, then, for glacial phosphoric acid are as follows: 1. Coagulation of albumin. 2. White precipitate with silver nitrate. 3. White precipitate with barium chloride, [All these tests should be successful; hydrochloric acid gives two of them, ( I and 2 ) but not three if pure. Sulphuric acid is distinguished by the heat evolved on mixing it with water. Nitric acid coagulates albumin, but does not answer to tests 2 and 3. Common phosphoric acid, li'hcn pure, does not answer to test I, nor when diluted to test 3, but if it contains sulphates as an impurity, will answer to test 3, and it may, if not pure, answer also to test 2. The "vegetable" acids like acetic, lactic, etc., etc., do not res- APPLICATION OF CHEMISTRY TO DENTISTRY. 373 pond to test I ]. If the phosphoric acid is in form of crystals, dissolve in as little water as possible, or melt by gentle heat, and then apply the test as above. If the crys- tals are dry, drop one of them into a solution of egg albu- min, and if a cloudiness or turbidity surrounds the crystal as it dissolves, test No. I is successful. At red heat the crystals should volatilize. As to the purity of the glacial acid: commercial glacial acid is a hard, glassy mass, but the pure is softer and wax-like. The acid is deliquescent, and dissolves readily in water, and in alcohol. To test the liquid of the oxychloride of zinc cements, it is necessary to show that it contains zinc and is a chloride. Take the reaction of the liquid, which should be acid. Pour a little of the liquid into a test tube, and add hydrochloric acid ; no precipitate should be noticed. Next add sulphur- etted hydrogen, either in gaseous form or in solution, and no precipitate should be noticed. Take a fresh amount, to which nothing thus far has been added, and add ammonium hydrate (Aqua Ammoniae will do), ammonium chloride, and ammonium sulphide; a white precipitate should be noticed. N. B. The precipitate may be greenish white, if there is iron present as an impurity. Now take still another sam- ple of the liquid, and cautiously add ammonium Jiydrate, letting it trickle down the side of the tube, and a delicate white zone of turbidity will be noticed. Shake it or add plenty of ammonia, and it will disappear. All these tests, if successfully obtained, show presence of zinc; confirm with blow-pipe. Next, to prove that it is a chloride of zinc. Take a fresh amount of the liquid, and add silver nitrate to it; a curdy, white precipitate becoming violet on ex- posure to light, and soluble in (plenty of) ammonium hydrate, shows the presence of a chloride. In testing the powder used in both oxyphosphate and oxychloride cements, attention should be paid both to its ingredients and quality; first, prove that it contains 374 DENTAL CHEMISTRY. zinc by dissolving in nitric acid, as dilute as possible, and testing as for zinc in the liquid, or by means of the blow- pipe. Next as to quality: its specific gravity should be 5.6, *it should turn yellow when heated in a test-tube, and be- come white again on cooling. Try to dissolve a little in water, and notice that it is insoluble; add to a mixture of it with \vater, a little nitric acid, and notice that it is dis- solved completely. To the solution thus obtained in nitric acid, (i) add silver nitrate : no precipitate should appear; to a fresh amount of the nitric acid solution, (2) add barium chloride: no precipitate should appear. Now take a fresh amount of the powder, add water to it, and a few drops of hydrochloric acid: then add (3) sulphuretted hydrogen: there should be no discoloration; to a fresh amount of hydrochloric acid solution, add (4) potassium ferrocyanide. A precipitate appearing should 'not be col- ored green or blue. Test (i) is for chlorides, (2) for sulphates, (3) for lead, (4) for iron. 562. Manipulation of vulcanite, etc.: much in re gard to this subject belongs properly to mechanical dentistry. When the rubber is ready for hardening or vulcanizing, the latter may be accomplished by submit- ting it for a time to the action of hot air, steam, or hot water. A strong boiler called a Vulcanizer is usually used, the metal of which should preferably be wrought. 563. To improve the color of rubber, Wildman advises exposing to action of alcohol in sunlight from six to twelve hours. Bending hard rubber may be accomplished after heating to the proper temperature as 240 to 280 F. Small pieces, uniformly thick, may be softened by oiling and holding over the flame of a spirit lamp. Large pieces or those of irregular thickness may be softened by im- mersing in oil. in a vessel and raising to the required temperature. *Determine the specific gravity according to Chapter I. APPLICATION OF CHEMISTRY TO DENTISTRY. 375 564. Parting the plaster: an ounce of castile soap (cut into thin shavings) dissolved in a pint of water, by boiling, is used for parting the plaster. 565. Coloring plaster: to color plaster add a little vermilion or burnt umber to the dry plaster. 566. Hardening the plaster: the operation may be hastened by mixing thick, adding common salt,* or using hot water, or by combining the three methods. 567. Compounding rubber: caoutchouc may be mixed with sulphur and the coloring matter, either by passing repeatedly between steam-heated rollers or by reducing the caoutchouc in the first place to a pulpy or gelatinous state (by the action of some such substance as carbon di- sulphide) and then mixing the sulphur and coloring mat- ter with it. [Wildman prefers to soften caoutchouc in oil of turpentine or in equal parts of coal naphtha, or benzine, and oil of turpentine]. From 5 to 50 per cent, of alcohol should be added to the solvent, in order that the latter may be at least partially recovered after the caoutchouc has softened. Wildman levigates the coloring matter and sulphur in spirits of turpentine, first grinding the coloring matter to a fine powder, then adding the sulphur and grinding thoroughly. He next adds a little of the pulpy caoutchouc, mixes thoroughly, and so on. 568. Substances used to color rubbers: the natural color of hard rubber, composed of caoutchouc and sulphur only, is a dark brown. Red oxide of iron and also vermil- ion are used to make re/1 rubbers; cadmium sulphide to make a yellow, and with oxide of zinc to make a lighter yellow. Ivory black is used to produce a black rubber. Various modifications of the different colors may be made. by combining the coloring materials in different pro- portions. 569. Testing rubbers chemically : to ascertain whether *Addition of salt is said to weaken the plaster. 376 DENTAL CHEMISTRY. metallic mercury is set free in the body of the rubber by the decomposition of the sulphide (vermilion) during vulcanization, a simple method is to digest the rubber in nitric acid, then test the solution for mercury in the usual way.* Sulphuretted hydrogen may be proved to be given off during vulcanization by heating a sample of the rubber to 32OF., for one hour and a quarter in a suitable receptacle, and collecting the gas in a solution of a lead salt. A black precipitate indicates formation of sulphur- etted hydrogen. *Prof. Salisbury says that some of his students have used the cop- per test for mercury in rubbers: no response to the test has been ob- tained before vulcanizing, but after vulcanization evidence of abund- ance of mercury has been obtained, showing a change to have taken place to a more soluble compound or to metallic mercury. ANALYSIS OF SALIVA, TEETH, ETC. 377 CHAPTER IX. ANALYSIS OF SALIVA, TEETH, TARTAR, AND URINE. 570. A complete course in salivary analysis is as essential to the dental student as one in urinary analysis to the medical student. i. Become familiar with the physical char- acteristics of the saliva: i. Cause the pa- tient to wash his mouth out thoroughly with a warm, dilute solution of sodium bicarbonate, and afterwards with cold spring water, if it can be obtained, or with cold distilled water. Brush the inside of the mouth lightly with a glass rod, moistened with a little dilute acid, when the mouth will be filled with a consider- able amount of clear, viscid fluid. Cause the patient to expectorate into a cylindrical glass vessel, tapering at the bottom and provided with a lip, so that the sediment may be col- lected and examined with the microscope. ii. While it is settling, note the color, odor, reaction, transparency, consistence, appear- ance of sediment, specific gravity: color 378 DENTAL CHEMISTRY. should be absent, so also odor; take the reac- tion with litmus paper, dipping both red and blue slips into the fluid at once; if neither change color, the reaction is neutral; if the blue is turned red, the reaction is acid; if the red is turned blue, the reaction is alkaline. A variety of litmus paper may now be obtained, which turns red in an acid liquid, and blue in an alkaline one. The transparency should not be great, for normal saliva is turbid; the con- sistence should be glairy, viscid, and there should be froth. Notice whether the sediment after standing some hours is opaque and whit- ish, or whether stringy masses are present in it. [The latter is not likely to be the case in saliva obtained as directed in (i) but is sometimes noticed in cases of chronic gastric catarrh]. N. B. In order to note the physical charac- ters in detail, to collect and examine the sedi- ment, and to ascertain the specific gravity, several specimens of saliva collected in separate beakers or cylinders should be conveniently procured, in order to save time. The first speci- men may be set aside, in order that the sediment may settle in it; the second specimen may be used for observation of the color, odor, reaction, and also for the chemical tests ; the third, in case of a scanty supply, may be set aside for dilu- tion in order to ascertain the specific gravity by methods hereafter to be explained. in. Next ascertain the specific gravity, ANALYSIS OF SALIVA, TEETH, ETC. 379 which can be done by means of the urinome- ter: The urinometer consists of a glass float weighted below with a bulb of mercury, and with a stem graduated from o to 60 at intervals of one or two degrees; the instrument should sink to zero when floated in distilled water in the beaker, which usually accompanies it. If there is plenty of saliva, the specific gravity can be obtained at once by floating the urinometer in the saliva, and reading off the number on the scale at the level of the liquid. It should average from 1002 to 1006, or possibly, 1008 or 9. If the amount of saliva is scanty, the spe- cific gravity may be obtained by dilution: take one part of saliva by volume (bulk), and add one part of distilled water to it so as to make enough liquid to 'fill the cylinder, or beaker used, say two-thirds full; take the specific gravity as before and multiply the last figure of it by 2, and the result is the true specific gravity of the saliva. iv. Next proceed with chemical tests, first for the normal constituents, next for possible abnormal ones. 57 1 . A. Qualitative tests for normal con- stituents. i. Boil a little of the saliva in a slender, long test-tube, held between thumb and fore- finger by the closed end; heat the upper part 380 DENTAL CHEMISTRY. only of the fluid. A turbidity noticed indicates presence of albumin. 2. To a fresh supply of the saliva, add a drop or two of ferric chloride: a blood-red color in- dicates presence of sulphocyanide. This test is sometimes performed by means of prepared test-paper: immerse strips of paper in an am- ber-colored solution of ferric chloride, to which a few drops of hydrochloric acid have been added. Let dry. A drop of saliva will give a red spot on such paper. The red color is re- moved by addition of a drop of mercuric chlor- ide. [The test may fail altogether, in which case the saliva must be distilled with phosphoric acid and the first of the distillate tested]. 3. Collect a plentiful supply of the saliva by chewing rubber, or by inhaling ether vapor into the mouth: add four times its volume of water, stir well, let settle, pour off the super- natant liquid from the sediment. Prepare some starch mucilage by rubbing a little starch into a thin paste, with a little cold water, then pouring into about half a pint of boiling water. Boil for five or ten minutes and when cool, de- cant the clear liquid. Pour some of the starch mucilage into a small beaker, add a little of the diluted saliva, lay aside for ten minutes in a drying oven where the temperature is about 95 to 104; in default of a hot chamber, place ANALYSIS OF SALIVA, TEETH, ETC. 381 the beaker some time in water of temperature of 104, or warm the mixture very gently in a test-tube over a flame, taking care by cooling with the hand that the temperature does not rise much above 95. Apply the tests for starch and for sugar, and it will be found that the starch has disappeared wholly or in part, and that sugar has been formed, showing pres- ence of dia static ferment (ptyalin) in saliva. [The test for sugar should be made as follows: procure what is known as Fehling's test-liquid, essentially an alkaline solution of copper sulphate, boil a little of it diluted with four parts of water in a test-tube, and if it does not lose its blue color on cooling it is fit for use. Now add a drop or two of the starch mucilage on which the saliva has acted, and raise just to boiling point again; reddish-yellow precipitate indicates presence of grape-sugar. Compare now the action of a weak solution of iodine in alcohol on the original starch mucilage, and on that which has been acted on by the saliva; with the orig- inal it should form a deep indigo-blue compound]. 4. Fill a tall beaker with dilute acetic acid say one part of the ordinary acid to two or three of water and let the saliva drop slowly into it; stringy flakes indicate presence of mucin. 5. To show the inorganic acids, evaporate the saliva to dryness in a porcelain crucible; do not withdraw the heat till the residue is well blackened or darkened from charring of the organic matter; when it is so, remove, let 382 DENTAL CHEMISTRY. cool, and add a little distilled water, stirring well, and adding a drop of acetic acid. Filter and divide the filtrate into three parts; to two add a few drops of nitric acid, and to one a solution of silver nitrate; a turbidity indicates presence of chlorides. The precipitate thus formed should be soluble in ammonia. To the other add ammonium molybdate solution and heat; a yellowish color, becoming possibly a precipitate, indicates presence of phosphates. To the third add a drop or two of hydrochloric acid and some barium chloride solution; a white precipitate shows presence of sulphates. 6. To show the presence of lime and mag- nesia, take a portion of the filtrate obtained in 5,, and divide it into two parts; to the first add ammonium oxalate solution: a white precipi- tate indicates presence of calcium (lime); to the second part add ammonia and sodium phosphate solution: a white precipitate indi- cates presence of magnesium. The calcium precipitate should be insoluble in acetic acid but soluble in nitric; the magnesium precipi- tate should dissolve completely in acetic acid on shaking. 572. B. Quantitatiye analysis. Ptyalin may be separated nearly pure by precipitating fresh saliva with dilute normal phosphoric acid and then adding lime-water; filter off precipitate and dissolve it in distilled water, from which it is to be precipitated by ANALYSIS OF SALIVA, TEETH, ETC. 383 alcohol, collected on a filter, washed repeatedly with a mixture of alcohol and water, dried, and weighed.* Mucin, obtained as in the qualitative method, can be col- lected on a filter, washed with alcohol, dried, and weighed. The weight of the saliva being known, the percentage of ptyalin, or of mucin, can be readily calculated by dividing each weight by the weight of the entire saliva used. Fatty matters can be estimated as follows: a definite quantity of saliva being evaporated to dryness over the water-bath, triturate the residue carefully, scraping off any that may adhere, and exhaust thoroughly with boil- ing ether. Evaporate in a weighed platinum capsule f and the increase in weight of the capsule represents the amount of fatty matter present. The operation should be repeated often enough to obtain a reasonably constant result. Potassium Sulphocyanide. Dissolve perfectly dry potassic sulphocyanide, 0.05 gram in water ( 100 C. c. ), and add to it ferric chloride till no more intensity of color is produced; then measure the volume of liquid. This is the test solution a. Now take a definite volume of the saliva, and place it in a small, graduated, cylindrical glass vessel; add to it a drop or two of hydrochloric acid and ferric chloride, with brisk stirring, until its maximum of intensity of color is obtained; call this b. Having carefully noted the intensity of the tint b, place three or four cylinders similar to that holding the saliva beside it on a piece of white paper in a good light; then add to one of these by means of a graduated pipette a few C. c. of the ferric sulphocyanide solution (a); make it up * In order to dry properly there is need of a drying oven ; filters are conveniently dried and weighed by placing them between two watch glasses held together by a clamp. For weighing there is need of a delicate chemical balance. | A nickel crucible may be used for this operation. 384 DENTAL CHEMISTRY. to the same volume as the saliva (b} using distilled water. After stirring well note the intensity of color by looking vertically downwards through the column of liquid, and compare it with that of the saliva. If not so deep a red tint, a fresh experiment must be made in the same way, but using more of the sulphocyanide test solution. We thus proceed till an equal intensity of color is obtained in the two columns of liquid. From the amount of the test solution a required, we can easily calculate the percentage of sulphocyanide in the saliva. (Charles). Each C. c. of the test solution (a) contains .0005 grams sulphocyanide. If, therefore, 10 C. c. of the test solution are required, the amount of sulphocyanide in the saliva is .0005 X 10 or .005, and so on. Divide the amount of sulphocyanide found by the weight of the saliva, and the quotient is the percentage of sulphocyanide. The chlorides may be estimated volumetric ally* that is by use of standard solutions, directly from the saliva after the removal of the organic constituents. Fifty cubic centimetres of saliva should be boiled and filtered. To the filtrate add an equal volume of saturated baryta solu- tion ( I volume barium nitrate, 2 volumes barium hydrate, each a saturated solution); this precipitates the organic constituents and phosphates. Filter, and to the filtrate add, drop by drop, a standard solution of mercuric nitrate, of which I C.c. precipitates .01 gram of sodium chloride. The number of C.c. used shows the number of iJoths of a gram of sodium chloride present. The filtrate from the baryta precipitate should be acidulated with a few drops of nitric acid, before the mercuric nitrate is added. *In volumetric analysis the determination is in general brought about by adding to a weighed quantity of the substance to be ex- amined a solution of some reagent of known strength, until the reac- tion is exactly completed. The operation is termed titration, and re- quires skill and practice. The student is referred to " Button's Vol- umetric Analysis." ANALYSIS OF SALIVA, TEETH, ETC. 385 573 Special tests for constituents of oral secretions : T. Storer How has arranged a series of litmus tests of oral fluids together with a system of nomenclature as fol- lows: first take with the foil-pliers a piece of blue litmus, wet it with parotid saliva and put the wet piece on a leaf from a foil book. In like manner treat the sub-max. saliva, placing the wet piece on the leaf below the other. Thus also test between the teeth, in carious cavities, pulp cavities, roots, sulci, pus-pockets, under cal- culi, plates, bridges, etc. Make the same tests in the same order with red litmus. Fill up the blank with the other statistics, and then note and record either the unchanged color of both the blue and the red by the symbol N, neu- tral, or the change of the blue to red by the symbol A acid; or the change of the red to blue by the symbol A* alkaline, as the case may be. As abbreviations for the different reactions, How sug- gests the following: 1L Alkaline. A Acid. N Neutral. I Slightly, alkaline or acid. L Obviously, alkaline or acid. U Decidedly, alkaline or acid. Excessively, alkaline or acid. [Dr. Oliver, of England, has prepared for use in urinary analysis, litmus paper charged with a definite quantity of alkali so as to distinguish several grades of acidity in re- action, such as sub-acid, add, hyper-acid, etc. It would seem as if these papers under certain circumstances might be of use in salivary analysis]. Detection of mercury in saliva: collect all the saliva possible in 24 hours, and acidulate it with dilute hydro- chloric acid (J part acid to 9 of water). The mixture is heated for two hours on a water bath, filtered, and filtrate marked (a), and concentrated to half its bulk over the 386 DENTAL CHEMISTRY. water bath. Go back to the precipitate on the filter, place it in a beaker filled three parts full with dilute hydro- chloric acid (i part acid to 6 parts water), and heat the whole over a water bath, adding from time to time small quantities of potassium chlorate, and constantly stirring to dissolve the organic residue. When this is completely dissolved, filter, and add filtrate to the previous filtrate marked a. Concentrate the mixed filtrates to one-fourth their bulk. The solution contains as dichloride, any mer- cury that may be present. To prove the presence of mercury, (i) place a drop of the solution on a gold or copper coin, and touch with blade of knife; a bright, sil- very stain will appear. (2) Place a few strips of pure copper-foil in a test-tube, and add a little of the solution, and boil; the mercury will be deposited on the surface of the copper-foil. Remove the strips and wash them with very dilute solution of ammonia, and dry them between blotting-paper. Then place them at the bottom of a nar- row glass tube (German glass), and apply heat; the mer- cury will be volatilized, and deposited as a ring of minute globules at the upper end of the tube. The character of these globules can generally be recognized by the eye. If, however, they are too small, remove the strips of cop- per from the tube, and dissolve the ring by the addition of a drop or so of dilute nitro-muriatic acid, and gently evaporate the solution. Dissolve the residue in a little water, and divide into two equal portions: (a) tested with a drop of dilute solution of potassium iodide, it gives a red precipitate of mercuric iodide, soluble in excess of potassium iodide solution; (b} a drop added to solution of caustic potash gives a yellow precipitate of hydrated mercuric oxide, insoluble in excess of liquor potassae. (Ralfe). Microscopic examination of the sediment: let the saliva settle in a conical vessel as directed, and examine the sediment with a power of 400 to 500 diameters; note ANALYSIS OF SALIVA, TEETH, ETC. 387 the salivary corpuscles, various kinds of epithelial cells. With higher powers bacteria, fungi, etc., may be studied. 574. Morphology of the human sputum : E. Cutter has made a partial list of the forms and substances found in the human sputum. 1. Mucous corpuscles. 2. Mucous cells swarming with the moving spores, probably of the leptothrix buccalis; not found in the mouths of healthy infants. 3. Mucous corpuscles distended with crystalline and other bodies. 4. Epithelia, ciliate and non-cili- ate. 5. Spirillum. 6. Vibriones. 7. Micrococcus spores. 8. Bacilli. 9. Spirulina splendens. 10. Gemiasmaverdansandrubra. 11. Alcoholic and lactic acid alco- holic yeast. 12. Vinegar yeast and lactic acid vinegar yeast. 13. Mycelial filaments of vinegar and lactic acid yeasts. 14. Leptothrix buccalis spores and filaments. 15. Papillae of tongue, usually infiltrated with spores of 14. 16. Mucor malignans. 17. Hairs of plants and animals. 18. Vegetations found in croupal membranes. 19. Pus corpuscles. 20. Blood corpuscles, white and red. 21. Clots of blood. 22. Granular tubercular masses. 23. Elastic lung-fibres. 24. Inelastic lung-fibres. 25. Lumen of veins and arteries. 26. Carbonized tissue from lungs. 27. Partially carbonized vegeta- ble tissues from smoke. 28. Oxalate of lime. 29. Uric acid crystals. 30. Cystine. 31. Phosphate of lime. 32. Triple phosphate. 33. Cholesterine. 34. Calculi, made up of one or more of 28, 29, 30, 31, 32, 33. These may all come under the appellation of "gravel of the lungs." 35. Other crystals whose names have not been made out. 36. Amorphous, organic, and in- organic matters, including dust and dirt inhaled from the atmosphere, 37. Portions of feathers of ani- mals and insects. 38. Potato starch. 39. Wheatstarch. 40. Elements of animal food eaten, cooked and uncooked. 41. Elements of vegetable food eaten, cooked and uncooked. 42. Cotton fibre. 43. Silk fibre. 44. Linen fibre. 46. Wool fibre. 46. Woody fibres.pitted ducts.etc. 47. Asthmatos ciliaris. 388 DENTAL CHEMISTRY. 575. Analysis of teeth and tartar: i. Qualitative analysis of the teeth. 1 . To show the presence of organic mat- ter, ossein, etc. Digest the teeth for a day or two in dilute hydrochloric acid (10 per cent). The earthy salts will be dissolved out, and what remains will be soft and elastic. 2. To show the earthy salts: place a few teeth in a clear fire and let them remain there until perfectly white. Powder, and dissolve in hydrochloric acid; dilute and add plenty of ammonia; a white, gelatinous precipitate oc- curs of phosphates of lime and magnesia. Filter, and to the filtrate add oxalate of am- monium: a precipitate of oxalate of calcium shows itself, indicating presence of lime not as phosphate; prove that there is carbonate by digesting powdered, uncalcined teeth in dilute hydrochloric acid, when an effervescence due to carbonic anhydride takes place. ii. Quantitative analysis of teeth: the teeth should be cleaned and reduced to powder in a mortar; weigh out 5 to 10 grams of powdered teeth, dry at 212 and then at 248, until it ceases to lose weight, i. The loss gives the water. 2. Take the mass thus obtained and calcine in a porcelain crucible at as low a temperature as possible; the loss in weight gives the organic matter, and the residue the ash. It is desirable to saturate the calcined residue with ammonium carbonate before weighing, and then to heat again to an elevated temperature. 3. Dissolve with the aid of gentle heat the ash obtained in 2, in as little ANALYSIS OF SALIVA, TEETH, ETC. 389 moderately dilute hydrochloric acid as possible; add ammonia in excess to the solution; a precipitate is thrown down, chiefly of calcium phosphate, with a little magne- sium phosphate and calcium fluoride. Filter, and wash the precipitate with water containing ammonia. 4. To the filtrate add ammonium oxalate to complete precipita- tion, boil, filter, dry the precipitated oxalate of calcium, ignite, and weigh; the result is the amount of calcium carbonate. 5. Go back to the precipitate obtained in 3, dissolve in strong acetic acid with the aid of heat (calcine any remaining undissolved, and estimate as pyrophos- phate), and to the solution add ammonium oxalate; boil and lay aside for 12 to 24 hours; collect the precipitated calcium oxalate on a filter, wash, dry, and ignite both pre- cipitate and filter. Care must be taken not to heat too strongly, and it is always advisable to moisten the precip- itate with ammonium carbonate before drying at a mod- erate heat and weighing. The result is calcium carbonate. Calculate the total amount of lime by adding the figures obtained in 4 and 5, and making the following proportion: IOO : 40 = weight obtained : x CaCOs Ca. 6. Evaporate the filtrate of 5 to small bulk, and also the washings of 5, mix with excess of ammonia, stir well, boil, lay aside for 12 hours; collect on a filter, wash with water containing ammonia, dry, ignite to redness, weigh. Calcufate .the magnesia by the following: 174 : 80 = weight obtained : x. Pyrophosphate Magnesia. of magnesium. (1 molecules). 7. To the washings and filtrate obtained in 6, add a mixture of magnesium sulphate, ammonium chloride, and ammonia, lay aside for 24 hours, filter, wash with water 390 DENTAL CHEMISTRY. containing ammonia, dry, ignite to redness, weigh. Cal- culate the phosphoric acid by the following: I : 0.216 = weight obtained : x. 576. in. Qualitative and quantitative analysis of tartar: A. I. Take a gram of tartar, calcine in air, dissolve residue in nitric acid; the part remaining undissolved is silica. 2. Boil the nitric acid solution for two hours with great excess of pure sodium carbonate, filter, and the bases, lime, magnesia, etc., remain on the filter as carbon- ate or oxide. 3. Wash the precipitate well, add ammo- nium chloride in excess, then ammonia. A precipitate shows presence of iron. Now precipitate the calcium by adding excess of ammonium carbonate. Filter. 4. To the filtrate add sodium phosphate, and a slight precipitate of ammonio-magnesium phosphate is obtained, which after 24 hours is complete. Calcination gives very slight residue, so that the magnesia may be reckoned as a trace. B. I. Now take a fresh supply of tartar, reduce to fine powder, weigh, treat with boiling water, which re- moves soluble alkaline salts and a part of the organic matter. Filter, evaporate filtrate to dryness, calcine, and the residue consists in the main of chlorides and sulphates and should be weighed. 2. Take the precipitate obtained in I, dry, weigh, cal- cine in an open porcelain crucible, weigh. Loss is animal matter. 3. Take residue obtained in 2, boil in concentrated sol- ution of ammonium chloride, which converts all the cal- cium carbonate into calcium chloride, filter, treat filtrate with calcium oxalate, wash trie precipitate, dry, calcine, weigh, and the result is the carbonate of calcium. 4. Take precipitate obtained in 3, wash it off from the filtei paper, dissolve in nitric acid; all is dissolved except a slight residue (silica): which should be washed, calcined, and weighed. The result is the amount of silica. ANALYSIS OF SALIVA, TEETH, ETC. 391 5. Add to the nitric acid solution obtained in 4, some ammonia enough to overcome the acidity. The phos- phates are precipitated. Now add acetic acid in excess; part of the precipitate is dissolved, part is not. Filter. Collect the precipitate on the filter, wash it off, calcine, and weigh. The result is phosphate of iron. 6. The filtrate contains the calcium phosphate: neu- tralize with ammonia, then add ammonium oxalate, filter, collect precipitate on filter, wash, calcine, weigh, and the result is calcium carbonate. Calculate the lime from this. 7. To the filtrate obtained in 6, add ammoniacal mag- nesium nitrate, and in 24 hours triple phosphate is com- pletely precipitated; collect on filter, calcine, weigh, and calculate the phosphoric acid from the weight as pyro- phosphate. ANALYSIS OF URINE. 577. A. Note the quantity of urine voided in 24 hours, the color, odor, specific gravity (using urinometer, section 563), reaction, (using litmus, section 563, n), transparency, and consistence. Normal urine is excreted in quantity about three pints in 24 hours, of straw-yellow color, aro- matic, characteristic odor, 1015 to 1025 in specific gravity, clear, with slight mucous " cloud " settling as the urine stands; normal urine is an easily dropping fluid like water. B. Get the urine perfectly clear by filtering, if neces- sary, through a number of filter-papers folded together, then test for albumin. Place clear, filtered urine to depth of an inch in a test-tube; hold latter inclined, and allow pure, colorless nitric acid to flow down side of test-tube into the urine. Use a nipple-pipette for delivering the acid. A clear-cut whitish band of coagulated albumin will be seen at the juncture of urine and acid, if the urine contains albumin. Confirm by taking fresh amount of clear, filtered urine and pouring into test-tube until two- 392 DENTAL CHEMISTRY. thirds full; add a drop or two of acetic acid and heat upper part of column of urine, holding test-tube at the bottom between thumb and fore-finger. A turbidity seen in the heated portion indicates albumin. C. Test for sugar, first removing albumin, if any is present, by boiling the urine to which a drop of acetic acid has been added, and filtering. Test the filtered urine for sugar as in section 569, A. 3. Or boil the filtered urine with an equal bulk of Liquor Potassae and a decided yel- low coloration becoming darker indicates sugar. Pay no attention to " flocks" seen in the liquid, as these are merely precipitated phosphates. D. Test for bile precisely as for albumin, test I, using, however, nitrous acid instead of nitric. [Nitrous acid may be made by boiling nitric acid with a bit of wood as end of tooth-pick]. A set of colors will be seen at the juncture, if bile is present. Of the colors, green is the most con- stant and the first in order from above downward. E. Let four fluidounces of the urine settle in a conical glass vessel covered over to keep out dust. After the sediment has well settled, pour off supernatant urine and test sediment chemically or examine with microscope. [Use of the latter is to be preferred, but will not be considered here]. Test for urates by warming a little of the sediment in a test-tube. If gentle heat dissolves the sediment, it is composed of urates. If not, add acetic acid, shake well and warm; if now it clears, phosphates are in the sediment. If no results thus far, take fresh amount of the sediment and add a drop or two of Liquor Potassae; if the sedi- ment become stringy, pus is present. Blood may be recognized by the color imparted to the sediment, which does not clear on being heated. Uric acid is often recognized by the naked eye, as it occurs in the form of reddish grains on the side or bottom of the glass. F. Estimate urea the chief normal constituent of urine, ANALYSIS OF SALIVA, TEETH, ETC. 393 (quantity 20 to 40 grammes daily). Use any of the con- venient instruments, as Marshall's, Greene's, Doremus's, Squibb's, some of which may be obtained with full direc- tions for use from the various dealers.* *For further information on this subject, the reader is referred to the author's work on " Diseases of the Kidneys." GLOSSARY. Acid Opposite of alkali. Section 129. Acidify To render acid. Actinic Name given to rays of sun-light having power to produce chemical changes. Aeriform Resembling air; term applied to gases and vapors. Alcohol Ethyl hydrate. Algaroth Compound of trichloride and trioxide of antimony. Allotropism Property of assuming different states and manifesting different chemical and physical properties. Alum Potassium aluminium sulphate. Ammonia Alum Double sulphate of aluminium and ammonium. Ammonia Ammonium hydrate. Ammonia Gas A compound of nitrogen and hydrogen. Ammoniated Snbmufiate Old term for mercur-ammonium chlor- ide, "white precipitate." Anaesthetic Substance which for a time diminishes sensibility, as ether. Anhydride Anhydrous acid, that is acid without water; oxide of negative element. Anhydrous Containing no water. Antiseptic Preventing putrefaction. Antozone Name given by Schcenbein to an electro-positive oxygen, which with electro-negative oxygen (ozone) forms ordinary oxygen. Aqua Ammonia; Ammonium hydrate solution. Aqua Fortis Nitric acid. Aqua Regia Nitrohydrochloric acid. Argillaceous Like, or containing clay. Argol Crud^e cream of tartar. Arsenic Arsenious anhydride. Artiads Atoms of even valence. Asbestos Incombustible substance occuring in nature and essen- tially a silicate of magnesium. GLOSSARY. 395 Aseptic Free from germs. Auriferous Gold containing. Baryta Old name for barium protoxide. Base Any substance which has one or the other of the two follow- ing characters: (a) of combining with acids, partially or wholly neutralizing them to form salts; (b) of playing the role of an electro-positive element in a combination. Basicity Property of playing the role of a base. Bi-carboiiate of Soda Hydrogen sodium carbonate. Bi-sulphuret of Carbon Carbon disulphide. Bleachine Powder Calcium hypochlorite and chloride. Blende Native zinc sulphide. Blue Vitriol Copper sulphate. British Alkali Sodium carbonate. British Gum Dextrine. Burnett's Disinfecting Fluid Contains zinc chloride. Butter of Antimony Antimony terchloride. Cadet's Fuming Liquor Arsenical alcohol. Calamine Native zinc carbonate. Calomel Mercurous chloride. See section 233. Caramel Burnt sugar. Carbolic Acid Phenyl hydrate. Carbonate of Soda Sodium carbonate. Carbonic Acid Gas Carbon dioxide. Carburetted Hydrogen Marsh-gas. Casein Proteid found in milk; essential constituent of cheese. Caustic Potash Potassium hydrate. Caustic Soda Sodium hydrate. Cellulose Substance forming walls of vegetable cells. Centigrade Thermometric scale on which the freezing point is zero, and the boiling, 100. Chili Saltpetre Sodium nitrate. Chlorate of Potash Potassium chlorate. Chloride of Lime See Bleaching Powder. Chloride of Potash Potassium chloride. Chloride of Soda See Labarraque's solution. Chlorous Having odor of chlorine. Chrome-alum Double sulphate of chromium and potassium. Chromic Acid Chromic anhydride. Cinnabar Native sulphide of mercury. Colloid-Substance non-crystallizable and passing with through animal membrane. 396 GLOSSARY. Concentrated With diminished proportion of liquid. Copperas Ferrous sulphate. Corrosive sublimate Mercuric chloride. Corundum Mineral containing oxide of aluminium. Cream of Tartar Potassium acid tartrate; potassium ditartrate. Condy's Fluid Contains potassium permanganate. Cumarin The crystallizable principle of Tonka bean. Cupellation A method of separating unoxidizable metals, as gold or silver, from oxidizable ones by use of cup-shaped vessels. Cyanogen A gas containing carbon and nitrogen. Decomposition Splitting up of molecules. Deflagration Phenomenon which takes place when two or more bodies reacting strongly on one another produce much noise and heat, melt together, etc. Dialysis Method of separating non-crystallizable (colloid) sub- stances from crystallizable by diffusion of the latter through ani- mal membrane. Dilute Not in full strength. Dippel's Oil Oily liquid from distillation of bones, etc. Distillation Process of separating the more volatile principles of a body from the less volatile, by means of heat. Dragon's Blood A resin. Dutch Liquid Ethylene chloride. Ebullition Boiling. Electrolysis Electro-chemical decomposition of a body. Epsom Salt Magnesium sulphate. Fahrenheit Name given to a thermometric scale on which the freezing point is 32, and the boiling 212. Ferment Body which, by mere contact with certain other bodies, sets up fermentation. Fermentation Splitting up of a body with evolution of gas, swelling up, and heat of the mass from no apparent cause. Fluorescence Appearance of emitted chlorine. Fluor Spar Calcium fluoride. Fowler's Solution A preparation containing arsenious oxide. Fuming Liquor of Libavius Stannic chloride. Fusible Metal Mixture of bismuth, lead, and tin. Galena Lead Sulphide. Gangue Miners' term for worthless matter containing useful metals. Glauber's Salt Sodium sulphate. Glucoaide Substance found generally in nature in the vegetable kingdom and derived chemically from glucose example, salicin. GLOSSARY. 397 Glycerole Substance in which glycerine is solvent or vehicle. Glycols Diatomic alcohols. Goulard Water Solution of subacetate of lead. Green Vitriol Ferrous sulphate. Green Salts of Magnus An ammoniacal platinum compound. Gypsum Native calcium sulphate. Horn-blende A native double salt of silicic acid, magnesium and calcium with ferrous oxide. Horn-silver Native silver chloride. Heavy-spar Barium sulphate (native). Hydrocarbons Substances formed by the direct union of carbon and hydrogen, as spirit of turpentine. "Hypo" or "Hyposulphite" Sodium thiosulphate. Isomerism Isomeric bodies are those having the same elements in the same proportions by weight. Kernies Mineral Mixture of antimonous oxide and potassium sul- phide. Ketone Substance formed by the action of oxidizing agents on secondary alcohols. Kupfernickel A mineral containing nickel and arsenic. Liebig's Condenser Apparatus for condensing steam. Labarraque's Solution Solution of chlorinated soda, sodium hypo- chlorite, and chloride. Lactose Sugar of Milk. Laughing Gas Nitrous oxide, nitrogen protoxide. Lime Unslaked, calcium oxide; slaked, calcium hydrate. Litre French unit of capacity. Lithate Old term for urate. Litharge An oxide of lead; lead protoxide. Lunar Caustic Silver nitrate. Lugol's Solution Contains iodine dissolved in solution of KI. Magendie's Solution Contains morphine sulphate. Magnetite Magnetic oxide, triferric tetroxide. Magnesia Magnesium oxide. Microcosmic salt Hydro-phosphate of sodium and ammonium. Metaphosphoric acid Term formerly used for glacial phosphoric acid. Miudererus, Spirit of Aqueous solution of ammonium acetate. M ousel's Solution Contains subsulphate of iron. Mosaic Gold Bisulphide of tin. Muriatic Acid Hydrochloric acid. Muriate of Morphia Morphine hydrochlorate. 398 GLOSSARY. Muriate of Ammonia Ammonium chloride. Nitre Saltpetre. Nordhauseu Acid Fuming sulphuric acid. \urnburg Gold An alloy of copper, gold, and aluminium. defiant Gas Ethylene. Oil of Vitriol Sulphuric acid. Oxide Binary compound, in which oxygen is the negative element. Oxj chloride Term given to a chloride of an oxide. Ozone A very active form of oxygen. Paris Green Essentially an arsenite of copper. Perissads Atoms of uneven valence. Peroxide of Hydrogen Hydrogen dioxide. Phosphor-iridium Metal prepared by heating iridium ore with phos- phorus (Holland). Combines with small quantities of silver forming the most flexible and resisting alloy of silver. Phenacetine An antipyretic, an acetyl compound of phenetidine. Platinum-black Finely divided platinum. Platinoid Kind of German Silver with i to 2 per cent tungsten. Platinum-sponge Platinum obtained by heating ammonio-platinic chloride. Platinor An alloy of platinum, silver, copper, zinc, and nickel. Potash Old name for potassium oxide. Polash Alum Double sulphate of aluminium and potassium. Prussic Acid Old name for hydrocyanic acid. Prussian Blue Ferrocyanide of iron. Pyrites, Copper Double sulphide of copper and iron. Pyrites, Iron Disulphide of iron. Realgar Native red sulphide of arsenic. Red Precipitate Mercuric oxide. Red Prussiate of Potash Potassium ferricyanide. Robertson's Alloy Gold i, silver 3, tin 2. Sal-alembroth Double chloride of ammonium and mercury. Sal-ammoniac Ammonium chloride. Sal-polychrest Potassium sulphate. Sal-prunelle Fused nitre. Saleratus Potassium dicarbonate. Sal-sodae Sodium carbonate. Sal-tartar Potassium carbonate. Sal-Tolatile Commercial carbonate of ammonium. Salt Cake Sodium sulphate. Saltpetre Nitre; potassium nitrate. Salts-EpsomMagnesium sulphate. GLOSSARY. 399 Salts-GlauberSodium sulphate,, Salts of Lemons / Salts of Sorrel \ p tassium dinoxalate. Salts of Tartar Potassium carbonate. Silica Silicon dioxide. Soda Old name for sodium oxide. Soda Ash Sodium carbonate. Sphalerite Zinc sulphide, (mineral). Speculum Metal An alloy of copper and tin. Sub-acetate of Lead Basic acetate of lead, acetate and hydrate of lead. Sub-muriate of Mercury Mercurous chloride. Sub-nitrate of Bismuth Bismuthyl nitrate. Sulphuret Old term for sulphide. Sulphuret of Iron Ferrous sulphide. Sulphuretted Hydrogen Hydric sulphide. Sulphide of Tin Stannous sulphide. Sulphonal Dimethyl-diethyl-sulphonyl-methane. Odorless, taste- less, crystalline solid. Hypnotic. Syntonin Parapeptone, acid-albumin. Talc Magnesium silicate. Tartar Emetic Potassio-stibyl tartrate. Turiibull's Blue Ferricyanide of iron. Valence Equivalence of atoms. Vienna Paste Contains calcium oxide and potassium hydrate. White Precipitate Mercur-ammonium chloride. White Vitriol Zinc sulphate. Yellow Prussiate of Potash Potassium f errocyanide. <\< Lh INDEX. Absorbents 303 Acetanilide 290 Acetates 271 Acetic Acid 63, 271 Acids 53 Ox-Acids 53, 54 Sulpho- Acids 53. 54 Acid, Acetic 271 Arsenous 175 Benzole 273 Boracic 175 Carbonic 118 Carbolic 247 Chromic 212 Citric 280 Eugenic 274 Hydrochloric 114 Hydrocyanic 61, 274 Hydrosulphuric. .. . 61, 55 Lactic 275 Nitric 186 Okie 274 Oxalic 275 Oxy benzole 278 Oxynaphthoic 280, 307 Phosphoric 180 Salicylic '. 278 Sozolic 279 Sulphuric 156 Tartaric 280 Trichloracetic 273 Valeric 280 Aconitine 282 Oleate 282 Tincture 283 Adhesion 3 Alantol 252, 307 Albuminoids 291 Albuminates 293 Alcohol 240 Absolute 241 Dilute... ...242 Alcohols 239 Alcohol 240 Aldehydes 269 Alkalamides GO Alkaloids 281 Cadaveric 281 Natural 281 Alloys 87,88,89 Alstonine 290 Aluminium 85, 189 Alloys 192 Compounds 193 Aluminium, tests 357 Alumina 194 Aluminium 189 Acetate 272 Chloride 194 Permanganate 194 Silicates 194 Alums 193 Alpha Xaphthol 307 Amalgam Alloys 147 Amalgam Fillings 148 Amalgams 138 Antimony 139 Cadmium 139 Copper 139 Gold 144 Palladium 144 Platinum 145 Silver 146 Tellurium 146 Tin 146 Zinc 146 American Weights 24 " Measures .... 24 Amidocaproic Acid 294 Amides 60 Amines 60 Ammonia Gas 101, 184 INDEX. 401 Ammonium Compounds 63, 100 Benzoate 273 Carbonate 101 Chloride 101 Hydrate 101 Amorphous 15 Ampere 22 Ampere's Law 11 Amyl Nitrite 261 Amylose 254 Amyloid substance 293 Analysis 32 Saliva 377 Tartar 390 Teeth 383 Urine 391 Volumetric 384 Anhydrous Acid 63 Anhydrous Phosphoric Acid 179 Anise Oil 228 Antifebrin 290 Antimony 172 Butter of 173 Tests for 348,357 Antimony Amalgam 139 Antimony Oxychloride 173 Antipyrin 284, 290 Antiseptics 303 Apomorphine 288, 290 Hydrochlorate 288 Arsenates 68 Arsenic 175 Arsenites 58 Arsenous Anhydride. . . 175 Tests for 357 Artiads 44 Artificial Teeth 195 Asbestos 130 Aseptol 279 Atmosphere 159 Atomic Weight 39 Atomic Weights 37 Atom 1,33,34 Atomicity 38 Atoms 38 Atropine 283 Attraction Atomic 1 Chemical 34, 73 Molecular . . 1 Of Mass 1 Auric Chloride 171 Auric Oxide 171 Avogadro's Law 11, 35 Babbitt metal 135 Bacilli 300 Bacteria 299 Bacteridia 300 Bacterium 302 Balsams...... -235 Barium 115 Chloride 115 Compounds 115 Nitrate 115 Tests for 350,360 Bases 55 Battery Galvanic IS Faradic 20 Storage 19 Bases 55 Beers 242 Bell metal 135 Bending Rubber 232 Benzoates 273 Benzoic Acid 273 Benzoin . 273 Benzoates 273 Benzine 217.221,222 BergamotOil 228 Betol 279,307 Bichromates 58, 212 Binaries ^6, 47 Bismuth 16 Alloys 163 Compounds 161 Oxyiodidc 307 Subnitrate 161 Tests for 348,357,358 402 INDEX. Blowpipe 344 Boiling Point 12 Bone 309 Boracic Acid 61, 174 Borates 58 Borax 99,196 Boric Acid 61, 174 Boroglyceride 244 Boron 174 Brass 135 Brittleness 4 Bromine Ill Bronze 135 Bronzes 136 Brucine 289 Buccal Mucus .* 324 Bunsen Burner 347 Cacao Butter 263 Cadmium 130 Cadmium Amalgam 139 Cadmium Sulphate 131 Caffeine Borocitrate 290 Cajuput Oil 228 Calcium 115 Compounds 116 Carbonate 117 Fluoride 119 Glyceroborate 245 Hydrate 118 Hypophosphite 121 Lactophosphate 278 Oxide US Phosphate 120 Sulphate 116 Sulphite 120 Camphene 225 Camphor 234 Mono-bromated 234 Oil 235 Spirit 234 Water 234 Cane Sugar 253 Cannabine 285 Tannate 285 Cannabis Indica.. . 285 Cannabinum Tannicum 285 Capillarity 7 Carat 167 Caraway Oil 229 Carbohydrates 253 Carbolic Acid 247 Carbon 203 Compounds ... .214 Carbonic Acid Gas 205 Carbon Compounds. . ..205, 214 Carbon Bisulphide 205 Carbonic Oxide Gas 205 Carbonates 58, 205 Caries 317 Carvacrol 229 Cells 19 Celluloid 257 Cellulose 256 Cement 119, 309 Cements Oxychloride 128 Oxy phosphate 127 Oxysulphate 129 Centigrade 31 Cerium 196 Oxalate... 275 Chains 216 Charles' Law 11 Chemical Arithmetic ... 71 Affinity 34, 73 Change 64,65,66, 72 Effects, Light 17 Equations <;9 Philosophy 32 Chemism 33 Chinoline 284 Chloric Acid 61 Chlorine Ill Compounds 113 Chloroform 264 Chloral 269 Chloral Hydrate 269 Chlorates 58 Chlorinated Lime.. . 120 INDEX. 403 Chromates 58 Chromium 212 Compounds 212 Tests for 359 Chromic Acid 61 Chromic Anhydride.. .. 212 Circuit 21 Citric Acid 280 Cinnamon Oil 229 Classification Elements 74,91 Organic Compounds. ..220 Closed Circuit '8 Cloves Oil 229 Coagulated Albumin .. . 293 Cobalt 211 Compounds 211 Tests for 359 Cocaine 285 Carbolate 286 Hydrobromate 286 Hydrochloride 286 Phenate 286 Phtalate 286 Cohesion 3 Cohesive Gold 167 Collagens 293 Collodion 256 Colloids 15 Coloring Rubber. ...... 231 Combustion .'. . . .158, 219 Compound 33, 34 Molecules ** Compounds Binary *6 Ternary 52 Compound Radicals (table of) Compounding Rubber.. 231 Compressibility 2 Conducting Power 83, 84 Condy's Fluid 96 Constants Of the elements 37 Copper 50,133 Alloys 135 Compounds 138 Corrugated Gold.. Coulomb Creasote Cream of Tartar.. 167 23 245 280 Creolin 305,307 Cresylic Acid 307 Croton Chloral Hydrate 270 Croton Oil 264 Crown Enamels 195 Crystal Gold 165 Crystallization 15 Water of 16 Crystalline Structure .. 80, 84 Crystalloids 15 Crystals 15 Systems 17 Cupric Sulphate 136 Current Electric 18 Induced 20 Cyanides 274 Cytisine 290 Decay 219 Decomposition 67, 69, 219 Definite Proportions 45 Deliquescence 14 Dental Amalgams 147 Dental Rubber 231 Dentine 309 Density H. **> Deodorizers 306 Derivatives 218 Derived Albumins 293 Destructive Agents 303 Dextrin 255 Dialyzer Dialysis Diastase Diluents Discoloration of Fillings 148 Disinfectants SO* Displacement 7 404 INDEX. Distillation 13 Ditaine 290 Divisibility 2 Ductility 4, 80, 83 Dutch Gold 170 Dyads 41, 115 Dynamo 21 Effect of metals on gold 169 Efflorescence 14 Elasticity 3 Elasticin 294 Elastin 294 Electricity 17, 21, 72 Dynamic 21 Galvanic 21 In the mouth 23 Static. 22 Voltaic 21 Electrodes 18 Electro-Motive Force.. 22 Electrolysis 21 Elements Classification 74, 78. 91 Negative 37. 40 Positive/ 37, 40 Table of 37 Empirical Formulas 215 Enamel 309 Energy 5 Equations 69 Equivalence 41 Erythrophleine 290 Eserine 290 Essential Oils 226 Ether 258 Sulphuric 258 Ethers 257 Ethyl Bromide 260 Nitrite 261 Oxy-Caffeine 290 Ethyl Series 238 Eucalyptus Oil 252 Eucalyptol 252 Eugenic Acid 274 Eugenol Evaporation Expansibility. . . Extension Fahrenheit Farad Faradic Battery. Fats Feldspar. 230 13 380 2 31 23 20 263 195 Fermentation 219, 294 Ferment Acetic Acid S97 Butyric " 297, 293 Lactic " . . 297, 298 Thrush 297, 298 Ferments 295, 299 Organized 296 Soluble 295 Unorganized 295 Dental 368* Ferric Compounds 209 Ferricyanides 58 Ferrocyanides 58 Ferrous Compounds.. .. 210 Fibrin 293 Fixed Oils 224,264 Flames Oxidizing 345 Reducing 345 Fluid 5 Fluid extracts 242 Fluorine 37,42, 114 Fool's Gold 170, 367 Force 5 Formulae 45 Binary 47,51, 61 Empirical 215 Graphic 215 Rational 215 Structural 215 Ternary 52, 61 Forms of Cells 19 Foot Pound 5 Formulae 45 Friction . . 7 INDEX. 405 Frits 196 Fungi 296 Fusion 367, 12 Fusibility 80 Fusible Alloys 162 Fusel Oil 243 Gallic Acid 262 Galvanic Battery 18 Gas 5 Illuminating 204 Gasoline 222 Galvanic Battery 18 Galvanic Electricity In the Mouth 23 Gay-Lussac's Law 65 German Silver 104 Germicides 303 Germ Theory 302 Glacial Phosphoric Acid 181 Globulins 292 Glucose 254 Glucosides 262 Glycerine 243 Glycerites 244 Glyceroborates 245 Gold 162 Alloys 169,170 Crystal 165 Cohesive 167 Corrugated 187 Compounds 171 Pure 164 Refined 16* Solders 171 Fools 170,367 Gold Aluminium Bronze 136 Gold Alloys 170 Gold Amalgam H4 Gold Base Plate 170 Green Gold 170 Guanin 294 Guaiacum 236 Gums 255 Gum Arabic 255 Gum Enamel 196 Gum Resins 235 Gum Tragacanth 256 Gutta Percha 232 Hardening Plaster 375 Hardness 4 Heat 12 Hexads 42,206 Hill's Stopping 233, 2.'9 Homologous Series 217, 238 Honey 255 Horse Power 5 How Substances Act. .. 73 Hydrates 55, 56 Hydriodic Acid 61 Hydrocarbons 220 Hydrobromic Acid 61 Hydrochloric Acid 61,113 Hydrocyanic Acid 62,274 Hydroferricyanic Acid. 62 Hydroferrocyanic Acid. 62 Hydrofluoric Acid 61 Hydrogen 105 Monoxide 106 Hydrogen Dioxide 109 Hydrogen Orthoborate. 174 Hydrogen Phosphate... 180 Hydronaphthol 238 Hydrosulphuric Acid... 61 Hyoscyamine 290 Hypochlorites 58,62 Hypophosphites 58,61,62 Illuminating Gas 204 Impenetrability Inclined Plane 7 Induced Current Insoluble Substances.. . 68 Iron 207 Cast 208 Dental uses 208 Pig a Wrought 208 Iron Compounds 209 406 India Rubber INE 231 110 267 268 202 50 291 218 291 195 222 270 100 236 278 275 278 291 293 37 184 230 65 131 301 294 6 , 72 64 119 >EX. Liquid 5 133 101 80 5 121 22 64 2 208 , 80, 83 206 206 170 11 1 1, 2, 33 24, 25 37 76 252 136 357 148 150 153 50, 136 293 Vulcanized .231 Litharge Iodine Trichloride .307 lodoform Machine lodol Magnesium Indium Iron Chloride 121 Is-atropyl Cocaine.. Hypochlorite 121 Oxide 121 Jerubebine Phosphate 121 Magneto-Electricity . . . Magnesia Kaolin Kerosene Magnitude Ketones Malleable Iron Labarraque's Solution . Lac Malleability 4 Shelllac 237 Compounds 206 Lactates Lactic Acid Manganese Dioxide . . . Mannheim Gold Lacto-Phosphates . . Lamine Lardacein M ass Latin names of elements Laughing Gas Matter Lavender Oil Measures .... Lavoisier's Law Melting Points Laws Avogadro's ..11 Mendeleef's Law Menthol Berthollet's 11 Mercury Of Fusion . . 12 Tests Of Machines . ..6 Mercury and Copper. . . Mariotte's ..11 Lead Mercuric Compounds . . Albuminate 307 Acetate 272 27 1 Chloride 148 Tests for 347, 348, 349, 353 272 ..300, Iodide 152 Oleate 275 Leptothrix Oxide 152 Leucin Sulphide 151 Lever Mercurous Chloride " Iodide .... Light . . . 17 Lime .. Mercurv Lime Water. . Metalbumin. . . INDEX. 407 Meta-elements 38 Metalloids 90 Metals 80 " Properties 80, 81, 85, 86, 87 Metric Equivalents 26 System 25 Meyer's Classification . . 78 Microbe of Caries 301 Of Pus 302 Microbes 301 Pathogenic 303 Protection Against 303 Micrococcus 300, 302 Milk Sugar 254 Miller's Experiments . . . 305 Mint Oil 230 Mineral Lubricating Oil 224 Mixture 34 Mobility 3 Molar Motion 1 Molecule 1, 33, 34, 35, 38, 39 Molecular Motion 2 Monad 41 Morphine 287 Acetate 287 Hydrochlorate 287 Phtalate 287 Sulphate 287 Mosaic Gold 170 Motion 1 Atomic 2 Molecular 2 Mouth Washes 306 Mucin 293 Muriatic Acid 64,113 Mycoderma 300 Myrrh 235 Myrtol 253 Naming Binaries 47 Napelline 283 Naphtha 222 Naphthalin 237 Naphthols 238 Beta-Hydro 238 Beta-Anhydro 238 Narceine Native Albumins. Neroli Oil Nickel " Tests Nitrates Nitrites. . 290 292 230 210 350 58 58 Nitric Acid 61, 186 Nitrogen 184 Monoxide 184 Nomenclature (old and new) 63 Non-Metals 90 Ohm 22 Ohm's Law 23 Oil 224 Anise 228 Bergamot 228 Cajuput .. 228 Caraway 229 Cinnamon 229 Carvacrol 229 Cloves 229 Eucalyptus 230 Eugenol 230 Lavender 230 Gaultheria 230 Mint 230 Neroli 230 Pyrethrum 230 Rose 230 Sanitas 225 Turpentine 224 Oils 224,226 Oleates 275 OleicAcid 274 Olein 263 Oreide 170 Organic Acids 270 Organic Compounds 214 Organic Chemistry 214 Organic Formulae 218 Organic Theory 214 Organized Ferments ... 295 Ox- Acids 64 Oxalates 63,275 408 INDEX. Oxalic Acid 63,275 Oxybenzoic Acid 278 Oxychloride Cement. .. 128 Oxygen 158 Oxynaphthoic Acid 307 Oxyphosphate Cement . 127 Oxypropylene-di-iso-amyi- amine 291 Palladium 199 Palladium Amalgam . . . 144 Palmitin 263 Paraffines 220 Paralbumin 293 Paraldehyde 269 Parotid Saliva 323 Parting Plaster 375 Peptones 293 Pepsin 296 Percentage Solutions. .. 27 Periods 75 Perissads 44 Petroleum 221 Pewter 132 Phenacetine 398 Phenates 250 Phenol 247 Phenol Camphor 250 Phenol Terchloride .... 250 Phenol Sodique 250 Phenyl Alcohol 247 Phosphates 58 Phosphorus 178 Phosphor-bronze 136 Phosphor-iridium 398 Phosphoric acids 61, 180 Pinchbeck 170 Platinum 199, 346 Tests for 355 Platinum Amalgam 145 Platinum Metals 201 Polymorphous 15 Potassa.. 64 Porosity 2 Positive and Negative elements 37, 40 Potassium 93 Bicarbonate 93 Bitartrate 280 Chlorate 93 Chloride 93 Hydrate 94 Iodide 94 Nitrate 95 Permanganate 96 Tartrate 280 Tests lor 350, 360, 361 Potential 22 Preparation of Dental Amalgam Alloys . . 139 to 147 Proof Spirit .. 242 Proteids 291 Prussic Acid 274 Ptomaines 281 Ptyalin 296 Pulley 6 Pulp Cavity 309 Pure Gold 164 Purple Of Cassius 172 Pus 302 Putrefaction 220, 295, 301 Pyrolusite 206 Pyrophosphates 58 Pyroxylin 257 Pyrethrum Oil 230 Quantity 22 Quantivalence 41 Variations 43, 49 Quicksilver 137 Quinine 288 Sulphates 289 Quinoline 284 Tartrate 284 Radicals 52, 215 Negative 58, 216 Positive 216 Reactions.. 66 INDEX. 409 Reading Binary Formulae 51 Reagent 66 Red Gold 170 Rees's Alloy 198 Refined Gold 164 Resins 235 Resistance 22 To air 84 Resorcin 251 Rhigolene 221 Robertson's Alloy 398 Robinson's Remedy. .. 249 Rochelle Salt 280 RoseOil 230 Rutile 203 Safrol 253 Salicylic Acid 63,278 Salivary Calculi 328 Saliva 319 Salivary Analysis 377 Salol 279 Salt 56, 57 Epsom 121 Sandarach 236 Sarkin 294 Saturated Solution 14 Screw Septicine 287 Series 217 Homologous 217 Sesqui 64 Shellac 237 Silex 203 Silica 203 Silicates 58 Silicon 202 Compounds 202 Silver 10! Alloys 10* Amalgam I* 5 Chloride 105 Nitrate 10* Oxide 105 Sulphide 106 Tests 3*7,349,353 Similor 170 Soda 64 Sodium 96 Sodium Compounds. .. 96 Bicarbonate 91 Borate 99 Bicarbonate 97 Glyceroborate 245 Hypochlorite 100 Hydro-Carbonate 97 Silico- Fluoride 308 Sulphite 308 Solders 90 Solid 5 Soluble Ferments 295 Solubility 14 Solution 13 Solvents 14 Sozolic Acid 279 Special Albumins. ... 293 Specific Gravity 8, 80 Of Elements 37 Heat K7 Volume 28 Speculum Metal 197, 136 Spiegel-Eisen 208 Spirilla 300 Spirit of Mindererus ... 271 Spirit of Wine Spirits Spirochcete Sputum Standard Pressure Standard Temperature Stannous Chloride Starch 254 States Of matter 5 Stearin 263 Steel Storage Battery Strontium, Tests 360, 350 Strychnine Sulphate 289 410 INDEX. Styptic Colloid 262 Sub-Acetate of Lead . . 272 Sublimation 13 Sublingual Saliva 324 Submaxillary " 323 Substitution 218 Sugar 253 Cane 263 Grape 254 Milk 264 Sulphates 58 Sulphites 58 Sulpho-acids 54, 62 Sulphocyanic acid 62 Sulphonal 399 Sulphur 154 Sulphurets . . 64 Sulphuretted Hydrogen 154 In the Mouth 298 Sulphuric acid 61, 156 Sulphurous acid 61, 154 Suppuration 302 Symbols 35, 7 Synthesis 32 Syntonin 291 Systems of crystals 16 Talmi Gold 170 Tannic Acid 262 Tannin 262 Tartar 327, 390 Emetic 280 Tartaric Acid 63 Tartar Emetic 280 Tartrates 63 Tellurium 153 Tellurium Amalgam . . 146 Tenacity 4, 83 Tensile Strength 82 Terebene 225 Terminations of Binary and Ternary Com- pounds 61 Ternary Compounds. .. 60 Terpenes 225 Terpin 225 Tests for metals 353 " blow-pipe 347, 348 Testing alloys 367, 368 Tests for cements 372 Testing rubbers 375 Tetrads 42, 189 Thermal unit 12 Thermo-electricity 22 Thermometry 30 Thymol 253 Tin 196 Alloys 198 Compounds 198 Tests . . 847, 348, 349, 356, 357 Tin Amalgam 146 Tinctures 242 Titanic Oxide 203 Titanium 203 Tooth structure 309 Torula 300 Triads 41, 160 Tribrom-phenol 308 Trichloracetic acid 272 Turpentine 224 Type metal 173 Types 218 Tyrosin 294 Ulexine 291 Units Electrical measurement. 22 Uranium oxide 133 Uric acid 294 Urates -.94 Valence 41 Valeric acid 280 Vapors 6 Variations In quantivalence . . . . 43, 49 Vaseline 223 Veratrine 290 Vibriones . . 300 INDEX. 411 Vienna paste 95 73 68 226 22 384 106 16 263 263 23 7 24 6 242 242 Writing acid formulae . " binary " " formulae of hydrates Writing formulae of salts 54 47 56 57 294 297 122 124 125 356,359 300 Vital force .... .... Volatile compounds . . . Volatile oils Volt Volume Specific 28 Yeast Volumetric analysis... Water Alloys 124 Water of crystallization Wax Solders 124 Zinc and tin alloy Zinc Chloride Bees 263 \Vaxes Oxide 127 Weber Oxychloride 128 Wedge Oxyphosphate 127 Weights Oxysulphate 127 Wheel and Axle Iodide 130 \Vines Tests 348,349,351, Wood soirit . Zooglcea UNIVERSITY OF CALIFORNIA LIBRARY Los Angeles This book is DUE on the last date stamped below. FEB3 Form L9-116m-8,'62(D1237s8)444