A TEXT-BOOK OF CHEMISTRY. HILL. A TEXT-BOOK OF CHEMISTRY FOR STUDENTS OF MEDICINE, PHARMACY, AND DENTISTRY BY EDWARD CURTIS fJILL, M.S., M.D. MEDICAL ANALYST AND MICROSCOPIST ; PROFESSOR OF CHEMISTRY AND METALLURGY IN THE COLORADO COLLEGE OF DENTAL SURGERY; PROFESSOR OF CHEMISTRY AND TOXICOLOGY IN THE DENVER AND GROSS COLLEGE OF MEDICINE, UNIVERSITY OF DENVER. WITH SEVENTY-EIGHT ILLUSTRATIONS, INCLUDING NINE FULL-PAGE HALF-TONE AND COLORED PLATES PHILADELPHIA F. A. DAVIS COMPANY, PUBLISHERS 1903 COPYRIGHT, 1903, BY F. A. DAVIS COMPANY. [Registered at Stationers' Hall, London, Eng.] Philadelphia, Pa., U. S. A. : The Medical Bulletin Printing-house, 1914-16 Cherry Street. TO WILLIAM HARMON BUCHTEL, M.D., LLD, THIS VOLUME IS INSCRIBED AS A TRIBUTE OF GRATEFUL ESTEEM 4751 PREFACE. THE present volume has been built up from lectures for ten years in medical and dental schools. The author has tried to make facts clear and simple, and has utilized topic gen- eralizations as much as practicable. The free use of formulas in the text is intended to familiarize students with chemic nomenclature and notation. It is hoped that the book will be a help to students of medicine, pharmacy, and dentistry. For material, the writer is particularly indebted to the following authorities: Bartley, Sadtler and Trimble, Novy, Hall, Bunge, Muter, Scoville, Mitchell, Rockwood, Wolf, Long, Taylor, Tanner, Simon, Leffmann, Gage, Draper, Purdy, Rohe, Neubauer and Vogel, and the "American Text-book of Phys- iology." He would also express his obligations to the publishers for the care and liberality they have shown in the mechanic make-up of the book. (v) CONTENTS. PAGE MEDICAL PHYSICS 1-69 General Definitions and Distinctions 1 General Properties of Matter 2 Special Properties of Matter: Solids 8 Liquids 10 Gases 16 Heat 19 Electricity 42 Magnetism and Electromagnetism 53 Crystallography 58 Osmosis and Dialysis 61 Sound 63 Questions 66 CHEMIC PHILOSOPHY 70-88 Elements 70 Atoms and their Properties 72 Atomicity 73 Atomic Weights 73 Polarity 74 Valence 75 Molecules and Formulas 77 Acids, Bases, and Salts 80 Chemic Reactions and Equations 84 Stoechiometry 85 The Periodic Law 87 Questions 87 INORGANIC CHEMISTRY 89-188 Metals: Discovery and Derivation 89 Ordinary Sources in Nature 90 Combination 90 Extraction 91 Physic Properties 95 Chemic Properties 99 Physiologic Properties 103 Uses 104 Metallic Groups , 107 Alloys 107 Metalloids 113 Oxids 131 Inorganic Acids 144 Hydroxids 151 Salts 154 Questions 183 (vii) Viii CONTENTS. PAGE THE CARBON COMPOUNDS 189-255 Hydrocarbons 191 Hydrocarbon Derivatives 200 Alkyl Salts 203 Alcohols 204 Ethers 208 Aldehyds 210 Acetals and Ketones 212 Organic Acids 213 Fats and Fixed Oils 219 Soaps 222 Carbohydrates 224 Glucosids 230 Vegetable Coloring Matters 232 Unclassified Bitter Principles 234 Phenols 235 Nitro-derivatives and Thio-compounds 236 Amido-phenols 237 Compound Ammonias 238 Pyridins, Azo and Diazo Compounds, Hydrazins 240 Nitrils and Carbylamins 241 Alkaloids 241 Proteins 246 Ferments . 251 Questions 254 ANALYSIS 256-293 Qualitative Analysis: General Directions 256 Finding the Metal 259 Finding the Acid, or Radical 263 Pyrology 269 Quantitative Analysis 273 Special Methods and Apparatus 279 Microchemic Tests 281 Nitrometry 282 Pharmaceutic Assays 283 Ultimate Analysis 284 Finding the Molecular Weight 285 Analysis of Amalgam Alloys 286 Refining cf Gold 287 Identification of Principal Fixed Oils 288 Detection of Common Sugars 289 Color-reactions of Common Alkaloids 290 Questions 292 INCOMPATIBILITY 294-306 General Rules 294 Summary of Solubilities of Medicinal Salts 295 Compound Solvents in Aqueous Solution 297 Gas-formation : Effervescence, Explosion, Combustion 299 Poisonous Reactions 300 Special Incompatibilities 300 Liquefaction on Trituration 302 Chemic Decomposition on Trituration 302 CONTENTS. ix INCOMPATIBILITY (Concluded). PAGE Incompatibilities of Water 302 Prescriptions 303 Action of Air, Light, and Atmospheric Heat 303 Practical Exercises 305 SANITARY CHEMISTRY 307-335 The Air 307 Water 309 Purification 312 Sanitary Analysis 313 Poisonous Metals 318 Adulterants and Sophisticants : Food 319 Drug Impurities 325 Antiseptics and Disinfectants 326 Questions 334 TOXICOLOGY 336-365 Definition 336 Acute Poisoning 336 Antidotes in General 342 Corrosives 343 Irritants : Mineral 345 Vegetable 348 Animal 349 Gases 350 Neurotics : Narcotics 351 Depressants 354 Convulsants , 356 Chronic Poisoning 357 Poisonous Bites and Stings 363 Questions 364 PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY 366-417 Chemic Composition of the Human Body 366 Bones 371 Teeth 372 Muscle 373 Nerve-substance, Epidermal Structures, Connective Tissues . . . 374 Cartilage ; the Viscera 375 The Blood 375 Secretions 380 Excretions 391 Animal Functions 396 Digestion 396 Absorption 398 Metabolism 400 Respiration 403 Food and Diet 404 Animal Foods 407 Vegetable Foods 408 Cooking .- 409 Beverages 410 X CONTENTS. PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY (Concluded). PAGE Autotoxemia 411 Infection and Immunity 412 Questions . 416 CLINIC CHEMISTRY 418-485 Gastric Juice 418 Practical Quantitative Analysis . . . 420 Milk 421 The Urine 425 General Properties 426 Normal Constituents 434 Abnormal Conditions 446 Microchemistry 459 Crystals 460 Granules 464 Casts 465 Cells 470 Bacteria 475 Differentiation of Nephritides 477 Diagnosis of Non-urinary Diseases 478 Urinary Calculi 483 Questions 484 APPENDIX 487-510 Solubility of Common Drugs 489 Arithmetic Constants 495 Equations of Manufacturing Chemistry 496 Ores, Rocks, and Minerals 500 Popular and Alchemic Names 502 LIST OF ILLUSTRATIONS. FIG. PAGE 1. Analytic Balance 6 2. Capillary Attraction and Repulsion 11 3. Hydrostatic Balance 13 4. Picnometer 14 5. Hydrometer 14 6. Westphal Specific Gravity Balance 15 7. Mercurial Barometer 17 8. Comparison of Thermometer Scales 22 9. Apparatus for Distillation 27 10. Radiometer 32 11. Lenses 35 12. The Laurent Shadow Polarizing Saccharimeter 41 13. Electrostatic Machine 44 14. A Galvanic Cell 46 15. Faure's Modification of the Plante Storage Cell 47 16. Horizontal Mil-am-meter 48 17. Electrolysis 49 18. Telephone 56 19. Systems of Crystallization 59 20. Sectional View of Blast Furnace 94 21. Apparatus for Determining the Melting-point of a Solid 112 22. Preparation of Hydrogen 114 23. Preparation of Chlorin 116 24. Sublimation of Sulphur 122 25. Preparation of Nitrogen 124 26. Preparation of Sulphuric Acid 147 27. Revolving Black-Ash Furnace 166 28. Interior of Pottery Kiln 175 29. Manufacture of Coal-gas 195 30. Quick Vinegar Process 214 31. Lard, Crystallized from Chloroform 220 32. Human Fat, Crystallized from Chloroform 221 33. Soap Coppers 223 34. Vacuum Pan 228 35. Apparatus for Solution (Rockwood) 257 36. Apparatus for Evaporation (Rockwood) 257 37. Apparatus for Filtration (Rockwood) 258 38. Apparatus for Fusion (Rockwood) 258 39. Bunsen Flame 270 40. Oxidizing Blow-pipe Flame (Light Blue) 271 41. Reducing Blow-pipe" Flame (Yellow) 271 42. Apparatus for Detection of Minute Amount of Arsenic 280 43. Nitrometer 283 44. Victor Meyer Apparatus 286 45. Dental Furnace 292 46. Cylinder for Nesslerization 316 47. Hemin Crystals 379 48. Human Milk and Colostrum 386 49. Spermatozoa and Bottcher's Crystals 389 (xi) xii ILLUSTRATIONS. FIG. PAGE 50. Reichert's Water-calorimeter 402 51. Feser's Lactoscope 423 52. Purdy's Electric Centrifuge 426 53. Squibb's Urinometer 433 54. Doremus Ureometer 438 55. Kjeldahl Method ......'.!'!.. 440 56. Esbach's Albuminometer 449 57. Sodium Urate Crystals 460 58. Cystin Crystals 461 59. Calcium Oxalate Crystals 462 60. Hippuric Acid Crystals 463 61. Narrow Hyaline Casts 466 62. Epithelial Casts 467 63. Granular Casts 468 64. Waxy Casts 468 65. False Casts 469 66. Pus-corpuscles 470 67. Normal Blood-corpuscles 471 68. Urinary Epithelia 472 69. Micrococcus Ureae . 475 LIST OF PLATES. PLATE PAGE I. Starches (Bartley) 226 II. Inorganic Poisons 280 III. Organic Poisons 282 IV. Absorption-spectra (Rockwood) 380 V. Vogel's Scale of Urine Tints 426 VI. Crystals of Phenylglucosazone (after v. JakscJi) 452 VII. Urinary Crystals 460 VIII. Tubercle Bacilli in Urinary Sediment (after v. Jaksch) 476 IX. Characteristic Microscopic Sediments 478 MEDICAL PHYSICS. GENERAL DEFINITIONS AND DISTINCTIONS. EVERYTHING about us consists of matter. Matter is per- ceived by the senses, especially by sight; but there are also many invisible substances. Air, for instance, though trans- parent and invisible, is as material in its nature as is iron or salt. Any appreciable change in matter is termed a phenom- enon. Natural, or physic, science is classified knowledge con- cerning matter and its phenomena. Chemistry is that branch of natural science which treats of the intimate composition of matter, the changes in com- position, and the principles governing such changes. It is, therefore, the most rational of studies, since it seeks to find an ultimate reason for every natural phenomenon. As an art, chemistry has discovered and prepared the greater number of medicinal agents now in use. A practical knowledge of chem- istry is as essential to the pharmacist and physician as is me- chanics to the engineer or draughting to the architect. Physics differs from chemistry in that it treats of the forces and motions of matter in the mass rather than its final com- ponents. The two sciences are, however, closely related, and an elementary knowledge of physics, or natural philosophy, is essential to the understanding of chemistry. In consonance with the definitions given above, a chemic change is one in which the composition of a substance is per- manently altered; a physic change affects only the form, and that temporarily. The conversion of water into steam or ice is an example of a physic change. The union of water with lime, forming lime-water, a new substance, is an illustration of chemic change. Experiment. Heat 1 gm. of iron filings for ten minutes; then weigh again. Explain change in color and increase in weight. Would these changes have taken place had the metal been heated in a vacuum ? Experiment. Mix equal parts of sulphur and iron filings, moisten with water, and set aside. In a few minutes the mixture becomes hot and changes to a black mass of ferrous sulphid. (i) 2 MEDICAL PHYSICS. Experiment. Mix intimately, but cautiously, with a spatula a teaspoonful of powdered chlorate of potassium with twice as much cane-sugar. Place the powder in a convenient vessel and drop on a few minims of strong sulphuric acid. A bluish flame is evoked, the sugar is charred, and a suffocating gas is evolved. GENERAL PROPERTIES OF MATTER. The general or essential properties or qualities inherent to all matter are the following: Indestructibility, extension, attraction, weight, divisibility, impenetrability, porosity, com- pressibility, elasticity, inertia, and mobility. Indestructibility. No particle of matter was ever created or destroyed by human or natural agencies. Everything is apparently subject to complete destruction in its final decay, but in reality there is only chemic change and new combina- tions. The vegetation of by-gone ages becomes coal; this is consumed into ashes and gases in the fire which chemic change produces and maintains; living plants live and grow by ab- sorbing the ashes through their roots and the gases through their stems and leaves; and thus the round of transformation goes on. Water can be resolved by electricity into its com- ponent gases, hydrogen and oxygen, the sum of whose weights in any given case is always equal to that of the quantity of the liquid decomposed. The great fact of the indestructibility of matter is the foundation of modern natural science. Extension. Extension is that property of matter by virtue of which it occupies space. All forms of matter, even though invisible, possess this property. The amount of space occu- pied by any given portion of matter is termed its volume, which implies all three dimensions: length, breadth, and thickness. Extension in two directions is called area, or square measure; in one direction, length, or linear measure. Mass signifies the quantity of matter in a body, and is equivalent to the product of the relative density or compactness of the substance by its volume. The term mass, however, is not identic with weight; mass is not affected by gravity, but implies resistance to mo- tion. Platinum has a density of about 1400 pounds per cubic foot; hence a mass 6 inches cube weighs 1 / 8 of 1400, or 175 pounds. The system of measurements employed by scientists in all parts of the world is the metric system. It is a decimal method, the unit of which is the meter, equivalent to 39.37 inches. A cube of water Vioo meter on each side (Vioooooo cubic meter), weighed at 4 C., is the unit of weight, and is GENERAL PROPERTIES OF MATTER. 3 called a gram, being equal to 15.43 Troy grains. The unit of capacity is the liter, represented by a cube Vio meter in each direction (V 1000 cubic meter). It is equal to 1000 times the volume of water weighing a gram, or, in the English system, to a little more than a quart. The subdivisions of each of these three units (meter, gram, and liter) are indicated by the following Latin prefixes: milli, Yiooo; centi, Y 100 ; deci, Y 10 ; the higher denominations by the Greek prefixes: deka, 10; hekto, 100; kilo, 1000; myria, 10,000. It is thus seen that a gram is the weight of a cubic centimeter of water, and that 1000 cubic centimeters, or a liter, weigh a kilogram. Metric abbreviations are derived from the first letters of each name: e.g., c.c., for cubic centimeter; mg., milligram, etc. The metric terms used in medicine and pharmacy are the liter, cubic centimeter, gram, milligram, and micromillimeter, the latter being a microscopic denomination equal to 1 / 100 o millimeter, or Vioooooo rneter; it is expressed by the sign or letter /*. The student should learn the doses of drugs accord- ing to the metric system, bearing in mind that a teaspoonful or fluidrarn of liquid medicines is practically the same as 4 c.c. The following prescription illustrates the advantages of the metric system in prescription-writing. The numbers rep- resent either grams or cubic centimeters, according as the sub- stance is liquid or solid. The perpendicular line stands for the decimal point, separating whole numbers from fractions: Ii Quininae sulphatis 2)400 Cafieinee citratis 1|200 Aeetanilidi 1|800 Fiat pulvis; divide in capsulas nurnero xij. Signa : One every three hours. Impenetrability. No two bodies can occupy the same space at the same time. There are many apparent exceptions to this axiom. Sugar disappears without increase in volume of the water. The air seems to offer no hindrance to the presence of other material objects. Experiment. Place a piece of lighted candle on a wide cork float- ing on water in a wide vessel. Over the cork and candle press down a tall bell-jar. They will be seen below the outside surface of the liquid. Divisibility. The limits to which matter may be divided are almost beyond comprehension. Take any solid substance and crumble it in a mortar or dissolve it in a liquid; yet we know that the farthest possible division has not been reached. Under a high power of the microscope the fine grains of the 4 MEDICAL PHYSICS. powder appear large and rough and obviously capable of fur- ther division. Regarding matter in solution, a grain of strych- nin renders distinctly bitter a whole barrel of water. How infinitely minute must be the imponderable particles continu- ally given off from a grain of musk, which will scent for years a closed apartment! Yet it is believed, on good mathematic grounds, that divisibility has its bounds, and this leads us to the molecular theory of the constitution of matter. Scientists hold that every substance is composed of infinitely minute separate par- ticles, or molecules, separated by interspaces that are compara- tively much larger (according to Maxwell, about 1 / 2 millionth inch in ordinary air). The molecules are in constant motion (8,000,000,000 collisions per second in air), striking against each other and so producing the varied forms of molecular energy known as heat, light, magnetism, and electricity. According to the relative proximity of the molecules to each other, generally speaking, we have three principal states of matter: solid, liquid, and gaseous, to which, perhaps, a fourth, or extragaseous including the luminiferous ether and the so-called radiant matter of artificial vacua may be added. These states are interchangeable under varying conditions of temperature and external pressure. By the aid of heat ice is converted into water, and this into vapor. Air itself has been frozen under great pressure into a gray powder. The con- version of a gas into a liquid or a solid is brought about either by reduction of heat or by pressure or both. Regarding the actual size of a molecule, the human mind fails to grasp its nearly infinite minuteness. Lord Kelvin esti- mates that they range from Vioooooooo to V 100 ooooo cm - in diam- eter. There are millions of molecules in the head of a pin. A crude comparison is that the volume of a drop of water is to that of each molecule of which it is composed as the size of the earth is to that of an apple. Minute as are molecules, they are known to consist of even smaller solid bits of matter called atoms, which exist, as a rule, only in combination, forming molecules. When the constituent atoms are alike, the molecules, and of course the substance which they compose, are termed simple; a compound molecule or substance is composed of unlike atoms. Attraction. The grand law of gravitation,- discovered by Newton, is to the effect that every portion of matter in the universe attracts every other portion with a force which varies directly as the mass or quantity of matter in the bodies, and inversely as the square of the distance. The term gravity is GENERAL PROPERTIES OF MATTER. 5 applied to the attractive force which the earth has for bodies on or near its surface. In addition to this molar form of attraction active at sensible distances, the molecules of each substance are held together by molecular attraction, and the atoms by chemism, or chemic affinity, which is similar to, if not identic with, magnetism. Molecular attraction is of two general kinds: co- hesion, or that between like molecules; and adhesion, or that between unlike molecules. The continuity of a drop of water is an example of cohesion; water wetting the finger is an illustration of adhesion. When cohesion is stronger than ad- Fig. 1. Analytic Balance. hesion, a liquid substance in contact with a solid takes and retains the globular form. In order for a solution of a solid in a liquid to be made, the attraction of the fluid for the solid must be greater than that of the molecules of the latter for each other. When the solution is saturated (contains all it can of the dissolved sub- stance), cohesion is just equal to adhesion. Heat, the repellent force, is the great antagonist of cohesion, whereas it may aid adhesion, as in the case of most solutions. In solids cohesion prevails over the repellent force; in liquids the two forces are about equal, and the molecules move around each other freely; 6 MEDICAL PHYSICS. in gases the repellent force predominates, so that the tendency of a gas is always toward greater expansion. Weight is the measure of gravity. When we say an object weighs a pound we mean that the earth, as a whole, draws it to an extent balanced by this certain weight. The greater the mass of the object and the nearer it is to the surface of the earth, the greater the attraction and also the weight. At the center of the globe a body would weigh nothing at all, since the attraction of the encompassing world-matter is equal in all directions. A fluidounce of water weighs 457 grains. To find the weight of a given volume of water divide by 0.96 (avoirdupois) or by 1.05 (Troy ounces). Specific gravity is the relative weight of a substance as compared, under similar circumstances of temperature and pressure, with an equal volume of another substance taken as a standard. Water is the standard for both solids and liquids; air or hydrogen for gases. In the latter instance we speak of the comparative weight as density rather than specific gravity. Porosity. The existence of inconceivably minute, though relatively large, spaces between the molecules has already been noticed. It is into these pores that in case of a solution the particles of the dissolved substance enter. The extent of these interspaces is increased by molecular motion (heat); hence hot liquids, as a rule, can dissolve more of a given substance than cold ones. The hardest and densest metals can be made, under hydraulic pressure, to show the presence of pores. Experiment. Mix 50 c.c. each of water and alcohol. Take the reading again in ten minutes, and note how much it falls short of 100 c.c. Compressibility. This property obviously depends on the preceding one, and, as we might expect from the relative dis- tances between the component molecules, gases are more com- pressible than solids, and these usually more so than liquids. That most liquids are less capable of compression than most solids is due largely to the absence in fluids of sensible pores or interspaces. The compressibility of solids is illustrated by the stamping of coins with dies. Elasticity. By this term is meant the tendency of a body to return to its original shape after being compressed, stretched, bent, or twisted, from which we have the four kinds, namely: elasticity of compression, of tension or traction, of flexure, and of torsion. The first form is a general property of matter, though varying greatly in different substances. Gases are the most elastic form of matter; liquids come next in order; solids are very variable. GENERAL PROPERTIES OF MATTER. 7 Inertia. There is always a cause for every effect, and the property of inertia signifies that nothing material can of itself change its position or condition. Without the influence of external agents everything in the world would remain the same, inert and unvaried for all time. The active agents of natural, as opposed to artificial, changes are, first of all, the bacteria, those teeming micro-organisms which keep going the circle of life on the planet by breaking down dead animal and vegetable matter into more simple and available forms for living things. Most of these germs are innocuous, but some give rise to deadly chemic products, which are, in turn, responsible for infectious diseases.. Mobility. All matter is in a state of constant motion; rest is only a relative term. We may distinguish between mechanic (visible or sensible) change of place and invisible motion, molecular and atomic the former giving rise to the physic forces of heat, light, magnetism, and electricity; the latter to the manifold manifestations of chemic energy. Velocity is the rate of motion in any given time. Mo- mentum, or quantity of motion, is the product of velocity and the mass. Force is that which causes, alters, or arrests motion. Energy is the capacity for doing work; it depends on the union of motion and mass. Potential energy refers to position or condition, as of the water in a mill-dam above the wheel; or of water-vapor, which in condensing gives out the same amount of heat required for evaporation. The potential energy of a pound of coal (11,000,000 foot-pounds) is equivalent to a hard day's work by a strong man. Actual, or kinetic, energy is that of matter in motion. Plants generate potential energy, which animals render kinetic. Work is energy applied to overcome resistance. The unit of work, according to the English system, is the foot-pound: that is, the amount of force required to raise one pound one foot in height; the corresponding metric unit is the kilogram- meter. A horse-power is equivalent to 33,000 foot-pounds per minute. Machines gain in force, but lose in space. The grandest law in Nature is that of the conservation and correlation of forces: nothing is wasted, nothing lost. The ra}-s of the sun have produced coal, the coal serves as fuel to the steam-engine, the engine runs the electric dynamo, and the latter gives back the heat and light first furnished by the sun. MEDICAL PHYSICS. SPECIAL PROPERTIES OF MATTER. The special properties of particular substances are modi- fications of the general attributes of matter. The three states of matter solid, liquid, and gaseous are dependent upon the balance between cohesion and heat: in other words, on the distance between the molecules. Every gas and liquid can be converted into the liquid or solid state by two methods, namely: by cold and by application of pressure, singly or com- bined. Nearly all solids likewise can be melted into liquids and then vaporized. A few solids sulphur, for example pass directly into the gaseous form on heating sufficiently. SOLIDS. The peculiar properties of solids worthy of mention are hardness, brittleness, tenacity, malleability, ductility, elasticity, flexibility, viscosity, and crystallizability. All of these are simply modifications of the essential property of cohesion. By the term hardness is meant resistance to scratching or mechanic erosion. We say that iron is hard, lead soft. The degree of hardness bears no relation to density; lead is half again as heavy, or dense, as iron. We judge of the relative hardness of any substance by comparing it with others taken as standards. Mineralogists use a convenient table of ten minerals, each of which represents a certain degree of hard- ness corresponding with a certain number. The scale is as follows: 1. Talc. 6. Feldspar. 2. Rock-salt. 7. Quartz. 3. Calcite. 8. Topaz. 4. Fluor-spar. 9. Corundum. 5. Apatite. 10. Diamond. The diamond is the hardest-known substance. It is used in miners' drills and for cutting glass; the cheaper glass- cutters are made of steel. Hard bodies are much used as polishing-powders, among which may be mentioned emery, pumice, tripoli, and diamond-dust. Blacksmiths and workers in iron and steel harden tools and implements by dipping them while heated into cold water. This process, called tempering, usually renders the metal more brittle. The best quality of glass is allowed to cool slowly, thereby becoming tougher and stronger; the process is known as annealing. Brittleness is a lack of cohesive power, shown by the body breaking when subjected to moderate strain or to a fall or SPECIAL PROPERTIES OF MATTER. 9 blow. All brittle substances are hard; but the converse is not true. The well-known brittle quality of glass has become a proverb the world over. Experiment. With a three-cornered file make a slight cut in a glass tube. Place a thumb on either side of the cut, on the opposite surface of the glass. With the remaining fingers make pressure toward the thumbs. A neat fracture takes place readily. When a body is once broken, it is usually impossible to press the fragments close enough together for cohesion to act. Glass and china can be mended only by the use of a different adhesive material termed cement, which forms, as it were, a connecting link between the broken pieces. In the case of wrought iron, however, a break can be remedied by the opera- tion of welding, by which the molecules of the separate frag- ments are made to flow around each other in the molten state, aided by the use of the hammer. Freshly cut lead can be made to cohere again on strong pressure. Experiment. Take two glass slides and place between them a few drops of water, pressing out the latter, and with it the atmospheric air. Considerable force will be required to pull the pieces apart. What two things are concerned in the resistance to the pulling efforts? Tenacity is that property of matter by virtue of which it resists a pulling force. This property varies greatly in dif- ferent substances, and even in the same body. A piece of wood, for instance, is more tenacious in the direction of the grain than across it. Closely related to tenacity are the properties of elasticity, ductility, and malleability. Elasticity of compression is a general property of matter. Elasticity of flexure or bending, extension or stretching, and torsion or twisting is restricted to solids. It is evident that in an elastic body the molecules return nearly or quite to the relative positions they occupied before being acted upon by the outside force or stress. Malleable bodies are such as can be hammered or rolled into sheets. Gold and copper are the most noteworthy of the metals in this respect. A piece of the former metal can be beaten into a film Vsooooo f an i ncn in thickness, and to 650,000 times the original area. A ductile substance is one that can be drawn out into threads or wires. Platinum can be spun into a web finer than that of the spider. Gold, iron, and copper are also remarkably ductile. Certain substances as sugar, waxes, and glass are ductile when heated sufficiently, and dresses even have been woven out of glass. Owing to increase of density, the strength 10 MEDICAL PHYSICS. or tenacity of a body is increased when it has been drawn into wire or rolled or hammered. A flexible body is one which will bend without breaking. It is usually also more or less elastic. In the case of a flexed body the molecules on the inner side must be crowded closer together, while on the outer aspect they are drawn farther apart. Metallic rods and wires, particularly copper, are, as a rule, quite flexible. Certain brittle materials are readily bent on heating. Experiment. Hold a piece of soft glass tubing in the flame. In a few seconds the glass can be bent, heated portion inward, to any required angle. Viscosity is a property exhibited by some brittle substances, on account of which they yield and bend under continued stress. If we fasten a piece of sealing wax horizontally by one end, and to the other attach a weight, in course of time the wax will be seen to be bent downward. Ice is viscous, as shown by glaciers conforming to the shape of the valleys through which they slowly move. Crystalline bodies are such as have a more or less regular shape. Most natural inorganic substances are crystalline; for example, common salt, alum, and sulphate of copper. Those substances which are not crystalline are termed amorphous: that is, without form. LIQUIDS. A useful and remarkable property manifested by liquids is that of capillary attraction and repulsion. Experiment. Hold a fine glass tube in a beaker of water, and another in a beaker containing mercury. The water rises in the capil- lary tube, because the adhesion between the two is greater than the cohesive force of the water. The mercury is apparently repelled by the glass, since the cohesion of the metallic liquid is greater than its attrac- tion for the glass. The most marked examples of these phenomena are seen in the smallest tubes, as a greater relative surface is thus pro- vided for the exercise of attraction or apparent repulsion. Capillary action is of immense importance in Nature and in every-day life. In this way the sap rises in plants and the oil in the lamp, the blotting-paper takes up ink, the towel dries our hands, and the filter-paper separates liquids from undis- solved solids. By the diffusion of liquids is meant their natural unaided physic admixture when their surfaces are brought into contact. This process will take place, though more slowly, when the SPECIAL PROPERTIES OF MATTER. 11 lighter fluid is placed on top the heavier, as alcohol on water. Some liquids will not mix with each other directly at all. Experiment. Shake a little water in a test-tube with an equal quantity of oil of turpentine, and notice how quickly they separate. Which goes to the top? The diffusion, or passage, of two liquids into each other through parchment-paper or an animal membrane is called osmosis. Generally speaking, the lighter of two liquids trav- erses a porous septum more rapidly than the heavier one; its flow is termed endosmose; that of the heavier liquid, exosmose. Crystalline substances have usually smaller molecules than amorphous ones; hence they pass more quickly through a porous partition. Bodies capable of ready osmosis are there- fore termed crystalloids; those otherwise constituted are called Fig. 2. Capillary Attraction and Repulsion. colloids, which means, literally, glue-like. (See also under "Osmosis.") The operation of separating colloids from crystalloids has been termed dialysis. By this process any crystalline poison, such as arsenic or strychnin, can be easily separated from the colloid food-contents of the stomach, in a case of suspected poisoning. Dialysis is also of use in the preparation of dialyzed iron and some other drugs. (See also under "Osmosis.") Pressure of Liquids. The perfect fluidity of water and most other liquids accounts for the well-attested fact that at any given point in a liquid the pressure is the same in all directions: up, down, or horizontally. This pressure is due to gravity, that is, to the weight of the superincumbent liquid, and, hence, of course, increases with the depth. Experiment. To show that water presses upward as well as down- ward: Attach a string to the center of a metal disk large enough to cover the bottom of a glass cylinder; a small lamp-chimney will answer. Draw the string through the tube, holding it taut, and press the cylin- 12 MEDICAL PHYSICS. der down into a vessel of water. At the depth of a few inches one may let go the string, and the upward pressure of the liquid will keep the disk from sinking. Experiment. To prove that at the same point the pressure is equal horizontally and perpendicularly: Take two long glass tubes, and bend one end of each to form a U, the open end of this facing upward in one, outward in the other, both openings being at the same level. Pour a fluidram ot mercury into each tube and immerse the U-ends in a deep glass vessel of water. The quicksilver will rise in both tubes to the same height. The free molecular movements and equal transmission of pressure in liquids cause their surface to be always level when at rest, since in this condition only is equilibrium possible; or, as expressed in the old saying: "Water seeks the lowest level." Masons, carpenters, and surveyors make use of a spirit- level for determining horizontal lines and planes. This instru- ment consists of a slightly curved tubular glass receptacle set for convenience in a block of hard wood, and nearly filled with alcohol. A small space is thus left for an air-bubble, which rises to the center of the glass when the instrument is hori- zontal. On account of the equal distribution of pressure in all directions, a small quantity of liquid may apparently counter- balance a much larger amount, as in the familiar example of the tea in the nozzle and the body of the tea-pot. The same principle is illustrated in the hydraulic press, used for exerting great pressure or for lifting great weights. This apparatus consists essentially of a large cylinder perforated by a narrow conduit, each fitted with a piston. When the water is passed through the small tube into the larger space it exerts on the sides of the latter a distending force as many times greater as the difference between the cross-section of the pipe and the inner area of the cylinder. Yet, in reality, the total amount of energy has not been increased, since the smaller piston descends a correspondingly greater distance than the larger one rises. The same principle of hydrostatic equilibrium is exempli- fied by artesian wells. The fountain-character of these wells is due to the pressure of water at a higher level upon that inclosed in a hollow between impervious layers of clay, and which is tapped by boring. "Water cannot rise higher than its source," and, owing to friction of soil and air, the heights of these wonderful fountains are probably much below the level of their origin. Pressure on Immersed Bodies. The difference between the pressures on the upper and lower surfaces of a body immersed SPECIAL PROPERTIES OF MATTER. 13 in a liquid is evidently equal to the weight of the liquid dis- placed, since such pressure increases in exact proportion with the depth. This difference represents likewise the apparent loss of weight of a solid substance when immersed in a liquid, or the so-called buoyant force of liquids. Experiment. Weigh a piece of iron in air and then suspend in water. How much does it appear to lose in weight? Now weigh the water and vessel before and after immersion of iron. How much do they appear to gain in weight '( Since the apparent loss of weight of the solid equals the weight of liquid displaced, it is easy to find by simple com- parison their relative weights, which in the case of water is Fig. 3. Hydrostatic Balance. called specific gravity. To find the specific gravity of the iron in the above experiment, we need, therefore, only to divide its weight in air by its apparent loss of weight when weighed in water. If we use metric measures the solid need be weighed only in air. It is then placed in a carefully measured quantity of water in a metric graduate. The number of c.c. the water rises is equivalent to the mass of the solid, and a comparison of this rise with the weight in grams of the solid shows at once the specific gravity. This applies to fine powders as well as con- crete masses. Experiment. Find the sp. gr. of a silver dollar and of powdered sulphur. 14 MEDICAL PHYSICS. The volume of an irregular body is readily estimated by weighing it in air and then immersing it by a string in water and weighing again. The apparent loss of weight in grams equals the volume of the body in c.c. If a solid is soluble in water, we may ascertain its relative weight in some other liquid not a solvent, multiplying the result by the known sp. gr. of the liquid employed. Experiment. Find sp. gr. of cane-sugar, using turpentine as a medium. With solids lighter than water a lead sinker is attached. The calculation is made as for heavy substances, bearing in mind, however, that the light object weighed in water appears to lose its own weight and more. For example, a piece of lead Fig. 4. Picnometer. 5. Hydrometer. weighing 10 gm. in water has attached to it a piece of cork weighing 2 gm. in air. The two now weighed in water weigh 4 gm. The apparent loss of weight is 12 4 = 8 gm. Divid- ing 2 gm., the weight of the cork, by 8 gm., its apparent loss of weight in water, we find its sp. gr. to be 0.25. The picnometer, or specific-gravity flask, is a thin, round bottle with a perforated glass cork and a counterpoise. The flask is usually made to contain exactly 1000 grains of distilled water at 60 F. If when filled with chloroform the weight is 1500 grains, we know that the sp. gr. of the latter must be 1.5. Experiment. Find the sp. gr. of alcohol with the picnometer. The sp. gr. of liquids, 'however, is usually taken with the hydrometer, which is an instrument consisting of a graduated SPECIAL PROPERTIES OF MATTER. 1 .-> stem above, a hollow cylinder midway, and a bulb below con- taining quicksilver or shot. The instrument depends on the theorem of Archimedes, that a body immersed in a liquid dis- places its own volume and loses weight equal to the weight of the liquid displaced, and that the immersed body sinks until it has displaced a volume of the liquid equal to its own weight. The stem of the instrument is marked so that the surface reading is 1.000 for pure water (at 15 C. unless otherwise stated), and so on up or down with solutions of known sp. gr. The Baume scale instruments are of two kinds: for liquids lighter than, and for those heavier than, water. The reading Fig. 6. Westphal Specific Gravity Balance. is generally taken at the top of the meniscus, or little ring of liquid clinging upward around the' stem of the instrument. Modifications of the hydrometer for special fluids are the uri- nometer, the lactometer (for milk), salimeters, saccharimeters, vinometers, and alcoholimeters. The sp. gr. of liquids can also be determined by weighing a solid body of known weight in them. It is evident that the apparent loss of weight of the solid is greater in the heavier liquid than in the lighter one, and their relative densities are obtained by a simple ratio. For example, a piece of iron loses, let us say, 2 gm. by weight in water, 1.45 gm. in other: the sp. gr. of ether is the ratio of 1.45 to 2, or 0.725. This prin- 16 MEDICAL PHYSICS. ciple is utilized in the convenient Westphal balance, consisting of a notched beam attached at one end to a perpendicular sup- port, and having at the other end a hook supporting a rider, a thermometer, and a glass plummet. When these are immersed in distilled water at 15 C. the arm of the instrument is exactly horizontal. In liquids other than water the sp. gr. is read at a glance from the numbered notches on which riders of various sizes are placed in order to bring the arm to the horizontal. GASES. The constitution of gases is in many respects more simple than the structure of solids or liquids. The Italian physicist Avogadro and the French electrician Ampere discovered and ^ demonstrated about the same time the following law: Equal volumes of all bodies in the gaseous state and at the same tem- perature contain the same number of molecules. The neces- sary corollaries of this principle are, first, all gaseous molecules occupy the same space; second, the relative weights of any two gases are to each other as the weights of their molecules. The volume of a confined gas is inversely proportional to the pressure brought to bear upon it. This statement is called Mariotte's law. One atmosphere (760 mm. of mercury) is taken as the standard of pressure. Charles's law is to the effect that the volume of any sub- stance in the gaseous state varies directly as the absolute tem- perature. It has been found that a lowering of temperature from 1 to C. reduces the volume of a gas by 1 / 273 , or vice versa. Hence at a point 273 below zero all molecular motion must cease and the molecules be in contact with each other. This is called the absolute zero, from which absolute tempera- ture is reckoned. In calculating the volume of a gas zero centigrade is considered the standard. The tendency to expansion exhibited by all gases is due to the repulsion between the molecules. All gases expand at a uniform rate for equal increments of heat: 11 / 300 o increase in volume for every degree above 0. The constant tendency of an inclosed gas to escape from its container is called its ten- sion, or elastic force. The tension and the density of an inclosed gas vary inversely as its volume. The diffusion, or mixing, of one gas with another depends upon tension, and the rapidity of diffusion varies inversely as the square root of the density of each gas. Wet membranes allow the diffusion of soluble gases more readily than do dry ones, as exemplified by the diffusion of carbon dioxid from the SPECIAL PROPERTIES OF MATTER. 17 Mood into the lungs. Damp walls are unhealthful, because they prevent normal diffusion of air. We live at the bottom of an aerial ocean at least ten times as deep as the watery oceans which envelop the land. The air, like all gases, is a perfect fluid, and hence subject to all the laws of pressure and equilibrium of liquids. The pressure of the atmosphere at sea-level is about 15 pounds to the square inch, or the equivalent of the weight of a column of mercury 760 mm., or 30 inches, in height. As we ascend from the level of the ocean the atmospheric pressure gradually lessens, so that at Denver, for instance, it will sustain a column of mercury but 25 inches high, and at an altitude of 3 1 / 8 miles only 15 inches. The barometer is an instrument for measuring atmos- Fig. 7. Mercurial Barometer. pheric pressure. It was invented by Torricelli in 1643, and consisted of a simple glass tube closed at one end. The tube is filled with mercury and then inverted in a basin of the same, when the metal sinks until its own weight equals the pressure of the atmosphere on an area the same as that of a cross-section of the tube. This primitive arrangement, properly graduated, is still in use under the name of the cistern barometer. The ordinary mercurial barometer consists of a long arm joined to a short one, the former being closed above, the latter open. The space above the quicksilver in the long tube is termed a Torricellian vacuum. The difference in level of the height of the liquid in each arm represents the atmospheric pressure. This varies with altitude and with the temperature and humid- ity of the air. At sea-level in fair weather it is 760 mm., or a 18 MEDICAL PHYSICS. little more than 30 inches. Fair weather is manifested by a high barometer; a sudden fall foretells a storm. It is readily seen that the barometer can be used for as- certaining the heights of mountains or the distance above sea- level at any elevation. For this purpose the convenient aneroid barometer is usually employed. It consists of an hermetically- sealed,, flat, circular box of corrugated sheet-iron exhausted of air. The sides of it are pressed in more or less with each varia- tion of atmospheric pressure, indicated by a needle on the dial- face connected with the interior arrangement of levers. On atmospheric pressure depends the action of pumps, siphons, bulb-syringes, pipets, and medicine-droppers. The pressure of the air (at sea-level) will sustain a column of water 34 feet in height, and this is evidently the greatest distance that water can be raised by means of a suction-pump. The propelling force of a liquid in a siphon is equal to the difference between atmospheric pressure and the weight of the liquid in the short arm, minus the same difference in the case of the longer arm. Light, bulky bodies float in air or are borne up to a certain degree by the buoyant force, depending on inequality of press- ure at different depths. For this reason, a pound of feathers as weighed in air weighs more than a pound in a vacuum. A balloon may rise to a great height, because of its great volume of gas lighter than air. The highest ascent was that of Glaisher in 1861, who attained an elevation of over 36,000 feet. Gases are absorbed by liquids and solids, the absorption in the latter instance being termed occlusion. The amount absorbed varies greatly for different gases, increasing with in- crease of pressure and decreasing with a rise in temperature. In most instances the absorption is accompanied by feeble chemic action. Charcoal is a striking example of an absorbent solid, taking up 90 times its own volume of ammonia-gas. Water has great avidity also for ammonia, 1 volume at 15 C. dissolving 783 volumes of the gas. Experiment. Fill a cylinder with ammonia by driving this gas out of ammonia-water with the aid of heat and collecting by upward dis- placement. Place the cylinder, mouth downward, in a vessel of water, and agitate slightly. Why does the water rise in the cylinder? The sp. gr. of a gas can be ascertained by filling a thin glass globe with the gas and comparing its weight with the weight of the same volume of air, or, more frequently, hy- drogen (density). Allowance must be made mathematically for differences in temperature and atmospheric pressure. HEAT. 19 Three or more volumes of combining gases condense into two volumes. Cardiac failure on going to high altitudes is due to sudden decrease in extracardiac without any corresponding decrease in intracardiac pressure, which remains about 760 mm., as shown by manometer. This difference leads to acute cardiac dilation. In estimating the pressure on the heart 6 mm. should be de- ducted for the tension required to overcome the elastic force of the air-cells. HEAT. Heat is molecular motion. Cold is a relative term, sig- nifying merely a low degree of heat. The principal source of heat, both directly and indirectly, is the sun, although the earth receives only about a two-billionth part of the solar radiant energy. The sun clothes our planet with vegetable life, which is used largely for fuel, either in the primary condition of wood or transformed into coal, gas, and oil. A layer of ice thirty-five yards thick could be melted annually by the direct heat of the sun. The fixed stars furnish us with no small amount of heat. The interior of the earth is thought to be in a molten state (with a hard, central core), as evidenced by volcanoes, geysers, and hot springs. The temperature increases as we descend into the earth: about 1 F. for every 50 to 100 feet. There is no seasonal change below 30 feet. Atmospheric temperature diminishes about 1 C. for each rise of 160 meters. Mechanic friction, percussion, and pressure are common causes of heat. We rub our hands or a patient's body to make it warm. Some savage people still start their fires by revolving the sharpened end of a stick of wood in another dry piece. It is only about seventy-five years since the flint and tinder were supplanted by matches. A beautiful natural illustration of the development of heat by friction is seen in the "shooting stars," or meteorites, celestial bodies of low density, which become so intensely heated on passing through our atmosphere as to burst into consuming flame. Artificial heat is produced generally by chemic action, especially by the oxidation (oxygen-combination) of substances rich in the elements carbon and hydrogen, as are all ordinary fuels. Animal heat originates in chemic action, namely: the oxidation of carbon and hydrogen in the tissues. Experiment. Add some sulphuric acid to water, and note heat produced. Is this a physic or chemic change? 20 MEDICAL PHYSICS. Whatever may be the special source of heat in any par- ticular instance, we are convinced that there has been merely a transformation of some other kind of energy into this. Transmission of Heat. This occurs in three ways: by con- duction, by convection, and by radiation. Conduction is trans- mission by continuity from one portion of a body to another, as when an iron poker grows gradually hot from the end which is in the fire to the opposite extremity. Different substances vary greatly in the facility with which they carry heat. Metals, as a rule, are good conductors. Wood is a poor conductor; hence is used for the handles of iron culinary vessels. Air is also a poor conductor. Woolen clothing is warmer in winter and cooler in summer than other fabrics, because of its loose texture. The air it contains in the pores prevents the inward passage of heat to the body in summer and the outward passage of body-warmth in winter. Poor conductors are employed to a large extent for packing purposes to prevent freezing or thaw- ing. Examples of such uses are sawdust for ice, straw for cellars, and asbestos for water-pipes. Gutta-percha and zinc- oxid cements are poor conductors, and are commonly employed to protect the pulp before filling a cavity with a dental amalgam alloy. Experiment. To prove that water is a poor conductor of heat: Pack powdered ice or snow firmly at the bottom of a test-tube, and boil the upper portion of the water above. The ice or snow does not melt. In convection heat is diffused by currents of liquids or gases, the warmer portion of the fluid rising, while colder streams, being heavier, descend to fill the vacated space. Ven- tilation, the renewal of air in mines and buildings, is accom- plished by convection, a double current of warm and cool air being established by reason of the difference of temperature inside and outside the inclosed space. Experiment. To show convection in fluids: Boil some colored anilin in water in a beaker. The transmission of heat by spheric wave-motion through the ether or the air is called radiation. This is the manner in which the radiant energy emitted by the sun comes to us. Non-luminous bodies also radiate heat with varying rapidity, a stone faster than leaves or grass, and these more quickly than water. Radiant rays are either reflected, absorbed, or transmitted. Polished surfaces are good reflectors of heat as well as of light. Dark, rough surfaces greedily absorb radiant energy; hence become quickly heated. Well-blackened stoves HEAT. 21 radiate more heat. Transparent and diaphanous substances generally transmit heat with little loss, and are therefore hardly affected themselves as to temperature. They are diathermous to solar heat, but more or less athermous to the slower waves radiated back from the earth: the principle of green-houses. The top of a mountain,, though nearer the sun, is much colder than the base, because of the lesser amount of soil to absorb the heat, and because the air itself retains scarcely any of the radiant energy which passes through it. The difference in temperature between direct sunshine and shadow is accounted for by the presence or absence of solar radiant heat, just as pulling down the window-curtains cools a room. Effects of Heat. The manifold effects of heat are all manifestations simply of the enhanced motion of the mole- cules. It is this quickening of molecular movements which constitutes heat the repellent force, the antagonist of cohesion. Heat expands and cold contracts. The principal exception to this rule is water, which expands one-tenth on changing to ice with a force of 30 pounds to the square inch. Sulphur, cast- iron, and type-metal expand on cooling. Gases expand and contract equally and uniformly; liquids and solids unequally. The action of applied heat is a double one: raising the tem- perature and changing the state of the substance acted on. Temperature, or sensible heat, is the direct manifestation of heat to our senses. We say that a body is warm or cold, meaning that it gives off heat to our hands or takes it from them. If a cup of boiling water is let stand on the table, it radiates heat until it is of the same temperature as the sur- rounding air. For the exact measurement of temperature (intensity, not quantity, of heat) we use instruments called thermometers, first invented in 1609. These consist essentially of a closed glass tube containing mercury, with a reservoir-bulb at the bottom and a scale of degrees. Heat expands the mercury, causing it to rise in the tube; cold has the opposite effect. There are three kinds of thermometers in use, the Celsius, or centigrade; the Fahrenheit, and the Reaumur. The first named is the one employed by scientists the world over; the second is the ordinary household instrument; the last is now used only in Russia, Sweden, and Denmark. The centigrade scale is to be understood as being used in this book whenever it is not stated to the contrary. Each thermometer-tube is first filled with mercury, which is boiled, and then the glass is sealed. To mark the scale two standard points are furnished by Nature, that of boiling water, 22 MEDICAL PHYSICS. or steam (the boiling-point), and that of freezing water or melt- ing ice (the freezing-point), or equal weights of snow and ammonium chlorid. The bulb of the instrument is placed in melting snow and then in steam, and marks are made corre- sponding to the summit of the mercurial column in each case. All that is left to be done is to divide the intermediate space into degrees of equal width: 100 for the centigrade, 80 for the Reaumur, and 180 for the Fahrenheit instrument. The part of the tube above boiling-point and that below freezing- point are divided in the same way into degrees. In numbering or %; and to convert P. degrees into C. degrees we multiply by 5 / 9 . One other thing needs to be taken into con- sideration, namely: that the P. zero is 32 below f.p. There- fore, to convert a centigrade reading into the P. scale we should multiply by 9 / 5 an d add 32; whereas the reverse operation requires that we first subtract 32 and then multiply by f> / 9 . Since Hg freezes about 40 and boils at 357 V 4 , some other substances must be used for the extremes beyond these points. Alcohol (colored) thermometers are employed for very low temperatures (alcohol freezes at 130),, and bars of platinum measure by expansion very high temperatures; no two solids have the same rate of expansion. Pyrometers are instruments for measuring temperatures above the b.p. of mercury. They depend on electric changes induced by heat or on expansion of gases. The figures given above refer to the b.p. of pure water at sea-level. A rise in altitude, by decreasing the amount of atmospheric pressure, lowers the b.p. at the rate of 1 P. for every 533 feet of ascent above the sea-level. The altitude of any place may be easily ascertained by applying this fact. When water is heated under more than ordinary atmospheric pressure, the b.p. is raised and the digestant action of the fluid much increased. Experiment. The culinary paradox: Fill a glass flask one-third full with water and heat till boiling thoroughly, then cork tightly and invert the flask. Ebullition quickly ceases. Why? It begins again and continues if cold water is poured over the flask. Why? Experiment. By means of a flask and a thermometer take the b.p. of water and estimate altitude. The effect of pressure upon the f.p. (or melting-point) is obviously to lower it (make the change more difficult) in sub- stances water, for instance which expand on solidifying. Examples are a snowball and the track of ice made by a sled in the snow; the f.p. rises when the pressure is removed. On the other hand, pressure aids (raises the f.p.) the solidification of liquids which contract on passing into the solid state. The presence of solids in solution renders freezing and vaporization both more difficult, and hence raises the b.p. and lowers the f.p. Examples of this fact are the use of salt on icy car-tracks and the making of ice-cream. Water saturated with common salt has a b.p. of 109; with K 2 C0 3? 135; with CaCl,, 179. Raoult's law is to the effect that the lowering of the f.p. of an aqueous solution below the f.p. of pure water is propor- tionate to the number of molecules dissolved in the unit of 24 MEDICAL PHYSICS. volume of the liquid, whatever be the nature and weight of the molecules. The b.p. of other liquids is not the same as that of water. Pure anesthetic ether will boil in the hand in a test-tube. Mercury changes into a gas at 357. Ammonia volatilizes from its liquid form at about the same temperature at which mer- cury freezes, namely: 40. Experiment. Find b.p. of alcohol. The f.p., or solidifying-point, of most liquids is identic with their melting-points when in a solid state. Melting ice and freezing water, for example, have precisely the same tem- perature. The most infusible metal is iridium, which melts at 1950; and next to this comes platinum. Medical thermometers are made self-registering by a con- striction of the lower part of the tube, which permits the passage of the liquid upward in small drops under the greater force of heat, but causes a break when contraction begins, gravity not being sufficient to force the mercury downward. The same principle is utilized in the maximum meteorologic thermometers. The minimum meteorologic thermometers con- tain alcohol and an index of black glass, which is sucked down by capillary attraction between it and the alcohol, and remains at the lowest level reached by the column of fluid in the tube. These two varieties are also called recording thermometers. Thermometers that have been used for a long time are likely to give slightly higher readings, owing to the crushing in of the glass at the bulb by external atmospheric pressure, the space not occupied by mercury having been made a vacuum. Thermometers should be seasoned for at least a year before marking, in order to let the glass reach its ultimate stage of contraction after the heating it has undergone. Specific Heat. Not all substances become heated with equal rapidity. The water in the tea-kettle is cool after the iron is heated, and remains warm after the vessel and stove have cooled. Except the gas hydrogen, water has the greatest capacity for heat of any substance; that is, it requires more heat to warm it and gives out more heat in cooling than any- thing else except hydrogen. For this reason a coast climate is more equable than inland weather; in the night the heat of the slowly cooling ocean flows over to the land, while by day the water draws off warmth from the rapidly heated sand and soil. The ratio of the capacity for heat of any substance as compared with an equal weight of water is termed its specific heat. Mercury, for instance, becomes heated 30 while HEAT. 25 the same weight of water rises only 1 in temperature. The specific heat of mercury is therefore 0.0333. That of iron is 0.1138; of air, 0.2375; of ice, 0.5040. Every substance has its own specific heat, which increases with temperature: more in liquids, except water. Experiment. Put on each side of a double porcelain vessel equal weights of water and mercury, and heat as equally as possible. Com- pute the specific heat of the liquid metal. Atomic heat is a constant: about 6.4. The specific heat of any substance equals its atomic weight divided by this con- stant. The various effects of applied heat depend upon ex- pansion, and include such phenomena as liquefaction, evapora- tion, distillation, sublimation, and solution. Liquefaction. This signifies the change from a solid to a liquid state. It takes place for each substance at a particular melting-point, which remains the same until all the body has been liquefied, when the temperature again rises. As already stated, the melting-point is, for the same substance, ordinarily the same as its f.p. Animal and vegetable substances are gen- erally decomposed without liquefying on heating sufficiently. Certain alloys melt at a lower temperature than boiling water, and are used extensively in automatic fire-extinguishers. Evaporation. The slow and natural vaporization of water that takes place continuously from the surface of the globe is .termed evaporation. The rapidity of evaporation varies directly with temperature, atmospheric dryness, and extent of surfaces of water and air exposed to each other; it varies inversely with atmospheric pressure. Chemists employ wide and shallow vacuum vessels for evaporating purposes. We have all experi- enced the oppressive discomfort of damp, sultry days when the air contained already as much water-vapor as it could, and hence the cooling process of evaporation from the skin was greatly impeded. It is easy to see that the sensible tempera- ture need not correspond at all with that shown by the ther- mometer. A rise of 10 C. nearly doubles the capacity of the air for moisture (5.4 gm. to a cubic meter at 0), but evaporation goes on, though much more slowly, even below the f.p. In changing from the liquid to the gaseous state great expansion takes place; a cubic inch of water becomes a cubic foot of steam. The student should remember that water when evaporated is taken up, not as a liquid, but as a vapor, which mixes with the air just as other gases do. The only distinction between a vapor and other gases is that the former condenses readily into the 26 MEDICAL PHYSICS. liquid form, while the latter do not. By critic temperature is meant the degree above which a gas cannot be reduced by pressure to the liquid form. The critic temperature of air is 194; of water-vapor, 400. The capacity of air for heat depends chiefly upon the pro- portion of water-vapor it contains. This fact makes a differ- ence of about 30 F. between sun and shade in the dry Rocky Mountain regions. When air contains so much water-vapor that the least lowering of temperature would precipitate the latter in the liquid or solid form as dew, fog, mist, clouds, rain, hail, or snow, the air is said to be saturated, and the temperature at the time is called the dew-point. The air seems dry if its tem- perature is much above the dew-point; moist, if the tempera- ture and the dew-point are nearly or quite the same. The air of a furnace-heated room contains more total water-vapor than does the cold air outside; but relative to the dew-point and to our sensations the outer atmosphere is humid, the inner dry. The air of a room when excessively dry can be made more moist by keeping a pan of water on the stove or furnace. The rela- tion of the temperature to the dew-point at a given time is usually expressed in the meteorologic reports as percentage of relative humidity. The hygrometer is a simple apparatus for estimating the relative humidity of the atmosphere. It consists of a glass tube filled with water and fitted with a wick, which covers and keeps constantly wet the bulb of one of two thermometers placed side by side. Evaporation of moisture from the wick cools the mercury underneath and lowers the temperature of this thermometer. The dryer the atmosphere, the greater the difference in readings of the two thermometers. Sensible tem- perature is that of the wet-bulb thermometer, and is usually about 10 F. less than the dry bulb in Colorado; much less difference is found near the sea-coast. Distillation. Artificial vaporization is used principally for the purification or separation of water and other liquids. It is conducted at the b.p. of the liquid distilled in an apparatus called a still. This consists essentially of a retort, or flask, in which the substance is boiled, and a condenser. The latter is a long glass or spiral copper tube connected with the retort and surrounded by a vessel or a larger tube in which cold water is kept running. The cold water condenses the passing vapor into drops, which run out at the lower end of the condenser. Experiment. Distil colored water, using a flask connected with a Liebig condenser, and catch the colorless product in a beaker. HEAT. 27 Ebullition in a boiling liquid is due to the heat suddenly expanding the gases contained in a liquid. It may be prevented to some extent by placing in the retort some porous substance, like pumice-stone, to absorb the gases. By fractional distillation is meant the separation by vola- tilization of one liquid from another, or of several from each other. It depends on different liquids having different b.p/s. To distil alcohol, for example, from a mixture of alcohol and water, such as wine, the liquid is heated only to the b.p. of Fig. 9. Apparatus for Distillation. alcohol, which vaporizes, leaving most of the water behind. Destructive distillation is a term applied to the vaporization, with chemic decomposition, of solid substances, such as wood. Sublimation. The direct transformation of a substance from the solid into the gaseous state is called sublimation, lodin, sulphur, camphor, and corrosive sublimate are examples of sublime substances. The process of sublimation is used mainly for purifying purposes, and is sometimes repeated (re- sublimation). 28 MEDICAL PHYSICS. Experiment. Heat iodin, and catch vapor in paper cone. Experiment. Heat impure ammonium chlorid in the bottom of a large test-tube; watch it sublime and collect in pure, white, crystal- line masses in the upper part of the tube. Solution. Heat aids the solution of solids in liquids, but interferes with the absorption of gases. The process of solu- tion is not thoroughly understood, but probably consists in a change similar to fusion, followed by mechanic admixture. When a solid substance dissolves in a liquid without the ap- plication of heat, the necessary heat is taken from the liquid itself, cooling it accordingly. If, however, a chemic reaction takes place, the liquid becomes warmer. A physic solution, therefore, is marked by a lowering of temperature; a chemic, by a rise in temperature. The solution of a gas in a liquid raises its temperature. Experiment. Make a saturated aqueous solution of potassium iodid. Is it cold or hot? Experiment. Dissolve a little quicklime in water. Is it hot or cold t A liquid which dissolves solid substances is said to be a solvent for them. Water is the best solvent for a great pro- portion of drugs and medicines; alcohol comes next in dis- solving power; then ether, chloroform, turpentine, and fixed oils. Percentage solutions are usually by weight. A fluidounce of water weighs 457 grains; the same quantity of alcohol, 374 grains. The solubility of any substance in a solvent is always the same at the same temperature, which for convenience is stated at 15 C. in the tables of solubility. Different substances vary greatly in their solvents and their solubility. Some are so soluble in water that they absorb moisture from the air and become liquid. Such bodies are called deliquescent or hygro- scopic. The opposite property of becoming dry when exposed to the air is termed efflorescence. When a solvent can take up no more of a substance it is said to be saturated; if it can take up a little more, the solution is concentrated; if it can take up a good deal more, the solu- tion is dilute. A saturated solution of one substance does not prevent the taking up of any other solid and may even aid such an occurrence. The total amount of two or more substances capable of being dissolved is always greater than that of any one alone. Experiment. To a solution of mercuric chlorid add excess of potassium iodid. The red mercuric iodid is first precipitated, then re- HEAT. 29 dissolved. Potassium iodid is also employed to aid the solution of iodin in water. A little cane-sugar makes borax more soluble in water. A practical knowledge of the solubility of common drugs is necessary to physicians in prescribing liquid mixtures. Water is the solvent to be chosen for most mineral and alkaloidal salts, gums, sugars, albumins, gelatins, and solid acids. Alco- hol is the solvent for resins, gum-resins (dilute alcohol), bal- sams, volatile oils, and stearoptens. Ether dissolves fats and fixed oils. Glycerin is a ready solvent for earthy salts (alum, borax) and tannin. Fixed oils dissolve sulphur and phosphorus. Carbon disulphid is a good solvent for sulphur. Chloroform dissolves gutta-percha. Turpentine is a solvent for paints, fats, fixed oils, and sulphur. Mercury dissolves nearly all metals except iron. A solution of a non-volatile inorganic substance in water is called a liquor; of a volatile or gaseous, an aqua. If, instead of simple water, the solvent used is a concentrated aqueous solution of cane-sugar, we have a syrup. Infusions are prepara- tions made by treating vegetable substances with cold water; decoctions are similar, but hot water is used instead of cold. Tinctures are alcoholic solutions of non-volatile (iodin excepted) principles of drugs; spirits are solutions in alcohol of volatile medicinal agents; essences are stronger spirits. Soluble substances are, as a rule, more soluble in hot than in cold water or other liquid. In case of a chemic solution, however, such as that of quicklime in water, the reverse is true, as there are in cold water more molecules present to enter into chemic combination than in the same volume of warmer water. Common salt is about as soluble in cold as in hot water. So- dium sulphate is most soluble in water at 33. The process of solution is aided also by pulverizing the substance to be dis- solved, thus rendering it more easy of access to the molecular attraction of the menstruum. Other means of hastening solu- tion are shaking the vessel and trituration of the solid with the liquid. When fluids mingle together physically they do so in no definite proportions. Fluids immiscible with water are held in suspension by the aid of some viscid excipient, as acacia, soap, gums, and white of egg, or in the form of soap with an alkali. Turpentine emulsion, for example, is made by rubbing up 1 part, by weight, of oil of turpentine with 1 of gum arabic, slowly adding the same amount of water with continual tritura- lion. Milk is a natural emulsion, the tiny fat-globules of which are held up and apart by shells of casein. Emulsions separate spontaneously on standing for a longer or shorter time, in this 30 MEDICAL PHYSICS. way also differing from true solutions, which are broken up only by the formation of crystals. Divers Effects of Heat. Heat aids chemic changes by in- creasing the space between the molecules, which are often decomposed into smaller ones. Organic molecules, being larger than inorganic ones, dissociate (are broken up) at a lower tem- perature than the latter, which, as a rule, can sustain heating to more than 1000 F. Experiment. Heat sugar on platinum. Note charring character- istic of organic compounds. Another interesting effect of heat is change of color. Orange-red antimony sulphid turns black on drying thoroughly. Mercuric iodid changes from scarlet red to orange-yellow on heating, becoming red again on cooling. Mercuric oxid at a very low temperature ( 200) fades from scarlet to pale orange. Experiment. Heat a little zinc oxid in a test-tube over the flame. It becomes light yellow, turning white again on cooling. Heat generally improves the malleability and ductility of metals. Most metals and solid compounds become brittle with great cold. Latent Heat. We have already seen that a solid body when heated sufficiently rises in temperature until its melting- point is reached, when the temperature remains stationary (if crystalline; still rises more or less if amorphous, like sealing wax) until liquefaction is complete, and then rises to the b.p., at which temperature the liquid stays until it is entirely vapor- ized. The heat which is used up thus in overcoming cohesion and changing the state of a substance is called by the rather misleading name of latent (hidden) heat. When a gas becomes again a liquid or a liquid a solid, all this heat is given out again as temperature. Steam-heating depends on this principle, the vapor, being condensed in the pipes, gives off its latent heat. We are familiar with the usual warm and sultry feeling pre- ceding a storm, this feeling being due to the giving off of latent heat during condensation of water-vapor. Latent, or insensible, heat performs a very important part in the muta- tions of the seasons, moderating sudden changes both of thaw- ing and of freezing. Change of material form always implies the presence of heat, and this heat is abstracted from the nearest convenient source. We cool a room or a street by sprinkling water on the surface; to change the water into vapor heat is taken from the HEAT. 31 air. The sudden expansion of the confined gas when a bottle of light wine or beer is opened reduces the temperature in the neck of the flask so much that a fog appears in it. Artificial ice is made on the same principle by the expansion of liquefied ammonia into gas in vacuum apparatus arranged in tanks filled with water, the cooling action being aided by the use of brine. Freezing mixtures depend on the utilization of heat in one or more of three ways, namely: by evaporation, by solution, and by expansion of gases. Considerable cooling is also effected by radiation. Drinking-water in warm countries is kept cool by placing it in flat vessels on straw or in porous water jugs. Experiment. Spray ether on the hand, or dip a thermometer for a moment in this liquid, and note how many degrees the temperature is lowered by the time the instrument is dry. Experiment. Mix some ammonium nitrate with an equal volume of water, and note effect. Just as heat can be produced by mechanic energy, so again it can be transformed into the latter. Stationary and locomo- tive steam-engines, hot-air and gas- engines are illustrations. All of these depend on pressure due to the expansive force, or tension, of matter in the form of gas. Calorimetry, Calorimeters are instruments designed to measure the quantity of heat in substances. There are four methods of calorimetry: By fusion, volatilization, and warming water or cooling. For instance, the ice-calorimeter consists of a block of ice with a cavity closed by a cover. The body to be tested is placed at a certain temperature in the cavity and left there until it has cooled to 0. The quantity of water pro- duced by the melting of the ice in the cavity is then weighed, and the relation between cause and effect expressed in heat- units. Again, the quantity of heat in a body can be readily measured by plunging it into a certain quantity of water at a known temperature and noting the number of degrees the water rises. Thermal Units. The amount of heat required to raise the temperature of a kg. of water 1 C. is called a calorie; to raise 1 pound 1 C., a thermal unit. One calorie equals 2.2 thermal units. If we mix a kg. of water at 80 with the same weight of pounded ice at 0, the water will dissolve the ice, and the temperature of the resulting liquid will be C. Stated briefly, 80 calories are required to convert ice into water. In changing the water into vapor 537 calories are used up. In other words, it takes more than five times as long (temperature of flame stationary) to "boil away" a given quantity of water as to raise its temperature from f.p. to b.p. 32 MEDICAL PHYSICS. Carefully performed experiments by the English physicist Joule have established the fact that the amount of heat neces- sary to raise the temperature of a pound of water 1 F., when transformed into mechanic energy is equal to 772 foot-pounds, or for 1 kg. 424 kgm. This number, therefore, is termed the mechanic equivalent of heat, and is usually expressed by the abbreviation J. LIGHT. Light is that form of radiant energy which gives rise to visual sensations. It is believed to consist in vibrations of Fig. 10. Kadiometer. ether, a continuous, imponderable, transparent, structureless, infinitely tenuous, perfectly elastic, frictionless, rigid, and in- compressible body filling all space, whether apparently vacant or occupied. This hypothetic ether is the great medium of transfer of energy: of gravitation as well as of molecular and atomic forces. Indeed, there are not wanting eminent physi- cists who hold that ether is the only true matter, and that molecules and masses perceptible to our senses are but varying combinations of ethereal vortex rings: in other words, of ether in motion. Light-waves proper differ from the accompanying heat-waves in being shorter, and hence of greater velocity; the LIGHT. 33 chemic, or actinic, waves of radiant energy are shorter and more rapid than those of light. The radiometer consists of a hollow glass sphere on a stand; the sphere is nearly a vacuum, containing about a millionth of an atmosphere: the so-called radiant matter. Within the globe are four little vanes, of aluminum, bright on one side, dark on the other, and suspended on a platinum support so as to revolve easily when brought into the sunlight or near a flame. The revolutions are due to the difference in force with which the light-waves act upon the two sides of the vanes, being absorbed most by the blackened surfaces. Experiment. Show presence of heat in the solar rays by lighting a piece of oiled black paper with a burning-glass. A fire might be started in this way even with a lens of ice. Experiment. Show actinic effect of solar energy on a piece of white filter-paper dipped in a strong solution of silver nitrate, dried in a dark place, then covered with a wire gauze and exposed to sunlight. Light travels always in straight lines, and its oscillations are at right angles to the plane of projection, like a rope shaken at one end. A ray of light is simply a line; a beam is a col- lection of rays, whether parallel, convergent, or divergent; a pencil differs from a beam only in its greater area. A luminous body is one which emits light. An illuminated object is one on which light falls. Transparent or diaphanous substances, like glass, permit the free passage of light-rays. Translucent bodies allow some of the light to pass, but not enough to define distinctly objects on the farther side. Opaque substances intercept all the light. Metals are opaque except in very thin layers, when they are translucent. A shadow is the contour projection of an opaque or translucent object produced by the stoppage of light. The principal source of terrestrial light is the sun. Other sources of natural light are the so-called fixed stars, meteors, comets, volcanoes, and the lightning-flash. Artificial light is usually the result of combustion or of resistance to the passage of electricity. The emission of light from a heated substance (above 1000 F.) without chemic action is termed incandescence; hence incandescent lamps (electric and Welsbach burners). Calorescence signifies nearly the same as incandescence; the heat-waves are converted into light-rays by concentration upon platinum or other metal. By phosphorescence is meant the power of some substances to emit light, accompanied with little or no heat, under the influence of nervous, chemic, thermal, or mechanic stimuli. 34 MEDICAL PHYSICS. Spontaneous phosphorescence is exhibited by fireflies and jelly- fishes as the result of nervous energy; it is also seen in a solu- tion of phosphorus, being due, in this instance, to slow oxida- tion; decaying organic substances, especially fish and the willow tree, often shine in the dark. Two pieces of loaf sugar rubbed together in the dark produce a phosphorescent glow. The sulphid and the cyanid of calcium are phosphorescent for some hours after exposure to the rays of the sun. From astronomic calculations, it has been determined that the solar light travels at the rate of 186,337 miles per second, a speed almost inconceivable; yet it takes 10,000 years for a ray of light to cross the visible universe. In water light travels three-fourths as fast as in air. Light is reflected just as other forces are, the angle of incidence being equal at all times to the angle of reflection. The amount of light reflected is greatest when the illuminant is near the horizontal; least, when at the vertic meridian. A rough reflector diffuses or disperses the rays of light in all directions, and so reveals its own outline; a smooth surface reflects the rays without altering their relation to each other, and thus furnishes an image of the luminous object or of an opaque body placed between the latter and the reflector. A concave mirror converges parallel rays of light; a convex mirror has the opposite effect. The student should study the images observed on the two sides of a lamp-reflector, and illus- trate their differences by diagrams. Images formed by actual union of reflected rays are termed real; when this union is apparent only and back of the mirror, they are called virtual images (plane, convex, and concave with point of light between principal focus and mirror). The point in the axis of a mirror at which reflected rays meet is termed the focus. This is always half-way between the center of the mirror and the center of curvature: that is, the center of the circle which would be produced by prolonging the curve of the mirror. The kaleidoscope consists essentially of three plane mirrors with pieces of colored glass set in a pasteboard tube. Befraction. A ray of light in passing obliquely from a rarer into a denser medium (as from air to water) is bent toward the perpendicular; away from the perpendicular when traveling in the opposite direction. It is for this reason that an oar appears broken at the surface of the water, and that stars a little below the horizon are visible. The index of re- fraction is the ratio of the sine of the angle of incidence to that of the angle of refraction; for the same substances it is Ll( JUT. 33 a constant quantity. The index of refraction from water into air is three-fourths; from air into water, four-thirds. When the angle of refraction of an incident ray is more than a right angle (critic angle) with the perpendicular, the ray does not (merge, hut is reflected; this phenomenon is called total re- flection. Experiment. Look upward obliquely into a glass filled with water. Note that one cannot see beyond the mirror-like upper surface. The mirage of the desert furnishes a beautiful example of total reflection, the image of trees and water beyond the horizon being reflected from denser strata of air at some dis- tance above the surface of the earth. In the same way that is, by difference in refractive power of its layers air itself becomes visible, as when heated by a stove or the sun. The diamond is the most refractive of solids, and its brilliancy de- pends mainly on this property of internal reflection. Another Fig. 11. Lenses. example of total reflection is the camera lucida attached to the eye-piece of a microscope and used for sketching objects. A prism is any transparent refractive body the sides of which form acute angles with each other. Prisms used in chemistry and medicine are termed lenses. According to form there are six classes of lenses, namely: convex, concave, plano- convex, plano-concave, concavo-convex (converging meniscus), and convexo-concave (diverging meniscus). Lenses which are thicker in the center converge rays of light; those which are thinner centrally have a divergent action. Convex glasses are used in spectacles for far-sight; concave ones for near-sight. A simple microscope consists essentially of a single convex lens. A compound microscope has two convex lenses; one is the object-glass, and the other in the eye-piece "magnifies" the enlarged image formed by the first lens. A telescope differs from a compound microscope in having a very large object-glass in order to catch as many rays of light as possible. An opera-glass contains a convex and a concave 36 MEDICAL PHYSICS. lens. The camera obscura cf the photographer resembles the human eye in the presence of a convex lens in the front part of the instrument., and a screen sensitive to light at the rear. The image is reversed in both instances. The stereoscope has two lenses, each of which is plano-convex toward the center of the frame, and double convex in its outer part. The ophthal- moscope is a small, concave mirror with a central opening, behind which small lenses are passed until the examiner can see the retina distinctly. Color. In addition to their refractive effects, prisms dis- perse or break up white light into its component colors. The prism usually employed for this purpose is triangular and equi- angular. The hues thus produced are infinite in variety, but seven colors stand out distinctly in the following order: Violet, indigo, blue, green, yellow, orange, red, the red being least refracted, the violet most. This dispersion of sunlight into the seven bands of the rainbow forms the solar spectrum. The violet waves are shortest (Veoooo inch) and most frequent (739,000,000,000,000 per second); the red waves are longest r/MtM incn ) and slowest (428,000,000,000,000 per second). The sensation of various color depends, therefore, on the num- ber of wave-impacts of light upon the retina in a given second of time; difference in brilliancy depends on the relative force of the blows; direct sunlight is too dazzling for the human eye. The intensity of light, as measured by the photometer, varies inversely as the square of the distance from the luminous source, as also with the angle of incidence. The sun's light is only one-seventh as intense at 5 above the horizon as at the zenith. The earth is nearer the sun in winter than in summer, but the increased obliquity of the solar rays much more than offsets the decrease in distance. White light, then, is composed of seven colors. This fact may be proved by analysis with one prism and by synthesis with another. Two colors that when taken together produce white are said to be complementary to each other. Examples of such are purple and green, red and bluish green, orange and cyan- blue, yellow and ultramarine, yellowish green and violet. Com- plementary colors are the best for producing contrast-effects in dress or otherwise. Experiment. Make a weak solution of a nickel and of a cobalt salt. When mixed together carefully the pink and the green colors unite to produce a colorless fluid. When we gaze at a certain color for some minutes the eye becomes fatigued for this hue, and if now we look at something LIGHT. 37 white or into space we see, not the first color, but its comple- ment. The color of any object is not of itself, but of the light that it acts upon, absorbing, reflecting, or transmitting. In the dark everything is black. A red light gives a corresponding tinge to all objects in its path. Looking through green goggles, even the snow takes on the tint of grass. Black represents the absence of all colors: that is, total absorption. A blue object is one which reflects or transmits to the eye only the wave- lengths of this hue. Transparent substances may have one color by reflected light, another by transmitted light; one may be the complement of the other. Experiment. Add to a beaker of water a few drops each of a solution of eosin and of hematoxylin. The mixture is green by reflected light, purple-red by transmitted light. Water in large masses appears blue or green. The blue color of the sky is owing to the refrangibility of the violet rays being greater than those colors at the opposite end of the spectrum; hence when the sunlight floods the atmosphere, the bluish waves are bent down to us most of all. The red and yellow waves are longer and stronger than the blue, and to this are due the color-effects of sunrise and sunset, when the solar light must traverse a much greater layer of air than when the sun is nearer the zenith. Experiment. Dry some red mercuric iodid on a sheet of paper over a lamp. It changes to yellow, the red color being restored on shaking or rubbing. The variation is ascribed to changes in crystalline structure. Iridescence is the name applied to the beautiful play of colors seen in cracks in glass, in soap bubbles, and in the plumage of birds and the lining of many shells. The phe- nomenon is produced by interference of secondary waves set up by thin films of air or by lines. Newton's rings illustrate color- effects due to interference by pressure. This apparent bending of the light-rays about lines and angles is known as diffraction. Diffraction-gratings are made of glass, the surface of which is ruled with fine lines very close together. They give a well- marked spectrum. By fluorescence is meant the bluish opalescence seen in kerosene and other petroleum compounds and in fluor-spar. The appearance is due to the refraction of the actinic rays in such a manner as to render them visible. Actinism. Most chemic substances are acted upon to some degree by the actinic rays that accompany solar light. This is particularly true of silver salts, hydrogen peroxid, and of 38 MEDICAL PHYSICS. iodids of various metals. Actinic changes are prevented or retarded by keeping susceptible substances in blue or amber- colored bottles. Salts of silver are decomposed by light, with deposition of metallic silver, especially in the presence of organic matter; hence they stain the skin. Photographers employ sensitized plates and papers coated on one side with a film of collodion, albumin, or gelatin, containing an emulsion of silver chlorid, bromid, or iodid. The development of negatives is done in a dark room with some reducing substances, like hydroquinon, and then a fixing agent, commonly sodium thiosulphate, which dissolves the unreduced silver salt and fixes the metal. The photograph is obtained from the negative by exposing the latter over sensitized paper to direct sunlight. Experiment. Illustrate photography by means of a leaf pinned to a piece of white filter-paper, previously dipped in a solution of silver nitrate and dried in the dark. Spheric aberration is the term applied to the confusion of images arising from the difference in focus between the rays which penetrate the central portion of a lens and those that are refracted by its outer zone. This defect is best corrected by the use of a circular ring diaphragm, which shuts off light from passing through the edge of the lens. A good illustration of such a mechanism is the iris of the eye. Chromatic aberration results from the difference in re- frangibility of the various color-rays. The violet come to a focus sooner than the others, and so give to the outer part of the visual field a disagreeable coloration. In microscopes the defect is overcome by combining a convex lens of crown glass with a concave meniscus of flint glass, constituting the achro- matic lens, in which two of the three principal colors are brought to a focus. Apochromatic lenses contain also calcium fluorid, and bring all three colors to the same focus. Phototherapy. Light stimulates the nerve-ends, and thus enhances nutritive activity. If a man is brought from dark- ness into the light, the carbon dioxid exhaled rises 14 per cent.; or, if the light is allowed to act on the whole body, the increase amounts to 36 per cent. Sunlight is capable of penetrating the entire thickness of the body, as has been proved by devel- oping photographs through the chest. The violet and extra- violet, or actinic, rays of light have been utilized for their chemic effect in the treatment of lupus. Spectroscopy. The spectroscope is an instrument for ex- amining the various spectra of different substances. It consists LIGHT. 39 essentially of one or more prisms, several convex lenses, and brass tubing to provide a proper focal distance. Flint glass has twice the refractive power of crown glass. By dovetailing one prism of the flint glass between two of the crown glass, the refraction of the latter is neutralized and the light passes through in straight lines, although dispersed into its component colors. The direct-vision spectroscope is all in one straight tube. The single-prism spectroscope consists of the collimator tube through which the light passes to the prism, and from this is refracted into the observing telescope. A third tube is some- times attached so as to throw another beam of light on the prism, to be reflected through the telescope to the eye, for the purpose of comparison. Experiment. Let each student view the sky through the direct- vision spectroscope, and note the rainbow of colors crossed by dark lines (Fraunhofer's), which are designated by letters in the best instruments. There are three kinds of spectra as studied with the spec- troscope: continuous, bright line, and absorption. The first is produced by heating (without vaporization) a solid or liquid body, in the flame near the slit of the spectroscope. Experiment. Show continuous spectrum with platinum wire. The first color to appear is red. Monochromatic light, of course, yields only the image of the color present in the flame. When a solid or liquid is converted into vapor by increase of temperature, the series of colored bands is marked here and there by bright lines, the number and position of the lines indicating almost at a glance the element or elements present in any compound. As the chlorids of the metals volatilize more readily than do other metallic salts, it is customary to dip the wire into strong hydrochloric acid before taking up the sub- stance to be tested. Experiment. Examine first the spectrum of a sodium salt; note the two bright-yellow lines, often appearing as one line (D line). Then examine and compare the spectra of salts of lithium, potassium, and strontium. The spectroscopic method of analysis is not only very convenient in many cases, but is also exceedingly delicate, re- vealing, as it does, the presence of only V2oooooooo grain of sodium. When a substance in solution or in the gaseous state is interposed between the slit of the spectroscope and the source of light, we get absorption-spectra: that is to say, dark lines and bands where the same substances held in the flame would 40 MEDICAL PHYSICS. yield bright lines or bands. The interposed gas or liquid seems to absorb the corresponding rays of the same wave-length as the rays it emits. The formation of absorption-spectra is much employed in organic spectroscopy, particularly in testing for blood and its derivatives. Experiment. Study and describe the absorption-spectrum of a 0.1-per-cent. solution of potassium permanganate, in a narrow test-tube held between the slit and the flame, in which a platinum wire is hung. The dark lines of the solar spectrum are due to absorption by the luminous atmosphere of the sun of the corresponding elementary rays in the solid solar sphere. By comparison with the absorption-spectra of terrestrial elements, it has been found that nearly all of these exist in the sun, and in the same way the chemic composition of many stars has been deter- mined. By means of this delicate instrument a number of rare elements have been discovered: cesium, rubidium, indium, gallium, thallium, and scandium. A most practical use of spec- trum analysis is the detection of adulterants and impurities in chemic preparations. Double Refraction. Some substances, as Iceland spar, have the peculiar property of breaking up a ray of light into separate rays. This is called double refraction. Experiment. Make a pinhole in a card and place over it a piece of calcite. Note that two points of light are visible, and that when the spar is turned around one point revolves about the other. The ray which is most refracted is called the ordinary ray; the other, the extraordinary, is the one which performs the circle about the first. Polarization. Light is propagated, as a rule, in all direc- tions, perpendicularly to the line of radiation. When by the action of Iceland spar, selenite, or other substance the luminif- erous waves are made to vibrate in a single plane, the light is said to be polarized, and the change is termed polarization. The Nicol prism is a modified crystal of Iceland spar, the acute angles of which have been ground down to 68 and the crystal sawed diagonally in two from one obtuse angle to the other, and the two pieces rejoined with Canada balsam. The balsam is used to produce total reflection of the ordinary ray, which passes out at the side of the crystal. Polarized light is not to be distinguished by the unaided eye. For this purpose we make use of two Nicol prisms, called, respectively, the polarizer and the analyzer. When the polar- izer and analyzer are parallel as to their axes, light passes freely; but, when the analyzer is rotated so that its axis is LIGHT. 41 at right angles to that of the polarizer, the ray is quenched. The polariscope is simply a combination of polarizer and ana- lyzer; a polarimeter includes also a circular scale and a tube for holding solutions to be examined. Experiment. The difference between ordinary and polarized light can be illustrated by taking a string and two pieces of cardboard with a slit in each. The string by itself can be made to vibrate in all direc- tions. When the boards are fitted over each other so that the slits 42 MEDICAL PHYSICS. correspond, the string can only vibrate in the direction of the super- imposed slits. When the slit of one board is at right angles to that of the other, all vibration is stopped. Many transparent bodies are optically active, i.e., rotate a ray of polarized light to the right or the left, so that the analyzer must be moved a certain number of degrees farther either way in order to shut off the ray of light from the polar- izer. Substances that rotate polarized light to the right are designated as dextrorotatory, and are indicated by the sign -fs those which exercise the opposite action are termed levorota- tory, and are marked . For medical purposes the polarimeter (saccharimeter) is employed mainly in the quantitative estimation of sugars in solution. The specific rotatory power of any substance is the angle in degrees of rotation effected by a gram of the substance dissolved in 1 c.c. of water in a tube 1 dcm. long. The s.r.p. of cane-sugar is-)- 66.5; of levulose, 94.4. Since the effect of optically-active media varies with the length and strength of the different color-waves, it is neces- sary in quantitative testing to employ monochromatic light, usually yellow and obtained by burning sodium carbonate in the flame of a Bunsen burner. The letter D used in polari- metric formulas signifies the D line of the solar spectrum, which is the location of the sodium bright lines in the spectro- scope. ELECTRICITY. The word electricity is derived from the Greek name of amber, which was discovered by Thales, about 600 B.C., to possess electric properties: i.e., to attract light bodies when rubbed. Twenty-two centuries later Gilbert, Queen Elizabeth's physician, found that many other substances were electric. In 1670 Boyle obtained the first artificial electric spark. Some- thing over one hundred years ago Franklin, by means of a kite and string, demonstrated the identity of lightning and electric- ity. The past quarter of a century has seen such great advance- ment in the practical application of this agent that there can be no doubt we are entering an age of electricity with the passing of the age of steam. The exact nature of electricity is unknown. It is believed to be a form of molecular motion or ether stress dependent on atomic rotation, though for convenience it is often spoken of as a fluid. It is convertible into heat and light. According to the manner of production, electricity is desig- ELECTRICITY. 43 nated as frictional or mechanic, inductive,, chemic, thermal, and vital. Ideolectrics is a general name for substances which gen- erate electricity by friction; anelectrics include non-electrics. Frictional electricity is of two kinds: positive and negative (+ and ). That produced by rubbing glass with silk is termed vitreous, or positive; that by friction between flannel and resin is called negative, or resinous. Experiment. Hang two pith balls from a support by a string of silk. Rub sealing wax with flannel and a glass tube with silk, and charge each of the pith balls by holding the glass or the wax near them. Note that when charged alike the balls repel each other; when unlike, they attract. Induction is the production of electricity in another body by the mere proximity of an electrified object. The pith balls are charged with electricity in this way. The charge is always of an opposite character -to that of the inductor: thus the glass charges the pith ball negatively. When + and electricities meet they are mutually neutralized or discharged, and the body affected is in electric equilibrium, or at rest. The following rules of electric attraction and repulsion are important: 1. Unlike electricities attract, like electricities repel, each other. 2. The total electric attraction or repulsion between two substances equals the product of their electric power. 3. The strength of electric attraction or repulsion varies inversely as the square of the distance. The electric machine is an apparatus for storing up elec- tricity produced by friction between a circular glass plate and silk, leather, paper, or amalgam. Induction or influence ma- chines are generally employed nowadays in place of the former machine. In these the plates are provided with small pieces of tinfoil, and are made to revolve near each other in opposite directions. Plate machines are affected by weather changes, as moisture conducts away the stored electricity. Electricity is distributed only on the surface of bodies, equally on a sphere, but mostly at the ends of other objects: the + electricity at one end, the electricity at the other. Condensers, or accumulators, are designed to hold a large amount of electricity in a small space, and depend upon the principle that the capacity of an object to hold electricity is increased by the proximity of another insulated object oppo- sitely charged. The Leyden jar is a familiar example. When thus stored up in waiting for liberation, electricity is termed static; when in motion, dynamic. The passage of electricity from one point to another takes place by conduction and, to a less extent, by aerial convection. MEDICAL PHYSICS. Metals, as a class, are good conductors, silver standing first, with copper a close second. Very poor conductors are called insulators, or dielectrics. Such are glass, rubber, dry wood, Fig. 13. Electrostatic Machine. air, and silk. Water is a better conductor than air, the con- ducting-power of which decreases with increase of temperature. The human body, particularly the skin, is a poor conductor of electricity, the average resistance being about 1000 ohms. ELECTRICITY. 45 Electricity escapes more readily from points than from smooth surfaces; hence the use of the combs on the condensers of some electric machines, and also the principle of the lightning- rod, which is meant to bring together quietly and gradually the opposite electricities of earth and sky. Atmospheric electricity is generally static, and is due to vegetation, to evaporation, and to the friction of the wind on the ground. It is distributed mostly in open spaces, and is most abundant about noon. It is either positive or negative: the former always when the air is quite clear. Lightning is the electric discharge from the positively (usually) charged clouds to the earth, on which negative elec- tricity has been induced. The flash itself depends on atmos- pheric resistance. The forms of lightning in order of fre- quency are sheet, linear, heat (too far away to hear thunder: more than fifteen miles), and globe. The course of lightning is generally zigzag, on account of the varying resistance tor its passage through different atmospheric strata. The earth is the great common reservoir of electricity, and occasionally light- ning ascends from the ground to the clouds when the latter are negatively charged. The effects of lightning on human beings are those of artificial electricity, namely: burns, escape of blood from the vessels, shock, deafness, blindness, paralysis, and sudden death from hemorrhage into the medulla. Persons at some distance from the spot where a "lightning-stroke" occurs often suffer from what is styled the return-shock. That is, on the approach of the electric force from the clouds the body becomes charged by induction with the opposite kind of electricity, which is suddenly lost when the terrestrial and atmospheric charges neutralize each other. Fulguration is a term applied to the effects of lightning; sideration, to the effects of electric cur- rents. Static electricity is used to some degree for medical pur- poses. It has one advantage over other kinds of electricity, and that is its greater tension or penetrating power or capacity of overcoming resistance; it can be administered through the clothing. Experiment. Show electric spark by means of a file, and the copper wires attached to a battery. The duration of each spark is from 23 to 46 ten-millionths of a second. Galvanic, or voltaic, electricity is that form produced by chemic action. A galvanic cell consists of a chemic solution, usually an acid mixture, in which are placed two (or three) 46 MEDICAL PHYSICS. plates, the upper ends of which are connected by copper wires. The plates must differ in susceptibility to the chemic action of the fluid. The one that is more acted on is called the positive plate; the other, the negative. In medical electric apparatus zinc is usually employed for the + plates; gas carbon for the negative. The wire attached to the + plate is termed the - rheophore, and its end the pole (cathode) or electrode; that attached to the plate is the + pole (anode) or electrode. Experiment. Construct a simple galvanic cell with a piece each of zinc and carbon in a dilute acid. Connect the plates with copper wires, and note that chemic action is more marked when the ends of the wires are made to touch each other. Fig. 14. A Galvanic Cell. The electricity generated by chemic action at the -f- plate seems to flow in a circle or current from the zinc to the carbon and thence over the wires to the zinc plate again. When the two wires are joined, the circuit is said to be closed; when separated, the circuit is open. Making and breaking the cir- cuit is another way of expressing the same thing. A battery is simply a combination of galvanic cells. The arrangement of the cells in a galvanic battery varies with the particular use desired. For medical purposes the cells are con- nected in series, or tandem: i.e., the carbon of one cell to the zinc plate of the next. They are linked here for intensity to overcome high external resistance, namely: that of the skin. ELECTRICITY. 47 When the internal resistance that of the battery-fluid is comparatively great, the cells are linked for quantity, carbon to carbon and zinc to zinc; this arrangement is known also as parallel, abreast, or in multiple arc. The battery-fluid, or electropoion, most commonly used consists of 2 drams of bisulphate of mercury dissolved in a pint of water, to which is added 3 ounces of powdered dichro- mate of sodium and then slowly 3 fluidounces of commercial sulphuric acid. The office of the sodium salt is to unite with Fig. 15. Faure's Modification of the Plante Storage Cell. the hydrogen set free from the acid in the action of the latter on the zinc. When hydrogen is not taken up in this way bub- bles of the gas soon form a coating on the carbon plate, inter- fering with the passage of the current. Silver-chlorid and other dry-cell batteries are coming into increasing use, because of their convenience and portability. In the storage, or secondary, battery plates of sheet-lead are immersed in dilute sulphuric acid, the dichromate being omitted. A current of electricity is passed through from he ordinary, or primary, battery. Hydrogen collects on one plate 48 MEDICAL PHYSICS. and oxygen on the other. The charge, or polarity, thus pro- duced remains for several weeks. Connecting the plates yields a current of a strength about double that of a primary cell, and opposite in direction. Storage batteries are also made from red lead rolled up together with two perforated lead sheets, with flannel between, and immersed in dilute sulphuric acid. Metallic lead collects on the cathode and the peroxid of lead on the anode through chemic decomposition when the current is on. Flaws or impurities in the zinc plates of a galvanic battery lead to the formation of local currents that tend, of course, to Fig. 16. Horizontal Mil-am-meter. weaken the main flow. To obviate this defect it is customary to coat the zinc with quicksilver, which forms a smooth amal- gam, and thus prevents the local action mentioned. The bisul- phate of mercury in the formula given above will keep the zinc plates well amalgamated. A rusty surface impedes the passage of the current, and care should be taken not to let the acid fluid come into contact with the external parts of the battery. The electric current is the result of a difference in poten- tial (charge) of different bodies or parts of a body: much on the same principle as that "water seeks its level." The elec- tromotive force (E.M.F.), or tension, is the total electric energy arising from a difference in potential. The volt is the unit of ELECTRICITY. 49 K.M".F. It is about equal to the power of a Daniell cell, or one- half the power of a Grenet cell. The actual working strength of a current varies inversely as the length and directly as the square of the diameter of the conducting-wire. The unit of resistance is called the ohm, and is equal to the resistance, at f.p., of a column of mercury of uniform thickness 106.3 cm. in length and weighing 14.45 gm.; or to that of a copper wire 250 feet long and 1 / 20 inch in diameter. The resistance of the Atlantic cable is 700 ohms. The unit of actual current is called an ampere (weber), and is equal to a volt of E.M.F. passing through an ohm of resistance. For medical purposes the ampere is divided into thousandths, i.e., milliamperes, of which from 1 to 100 or more may be administered, according to the special indications. The milliamperemeter is an instrument for measuring current- strength in the medical application of electricity. It consists essentially of a magnetic needle, around which the conducting- wire is made to pass. The degree of deflection of the needle thus occasioned (by induction) indicates the exact strength of the current. The current is regulated, decreased, or increased by the introduction of more or less of a poor conducting mate- rial, as charcoal or water, or coils of German-silver wire, known technically as a rheostat. Other units used in electric measurements are as follows: The coulomb, or unit of quantity, the force of a dyne at 1 cm., is an ampere-second: i.e., a current of an ampere in one second of time. The farad of static electricity is equivalent to a coulomb. The watt, or unit of total electric energy, represents the product of the voltage and amperage, and is equivalent to V?46 horse-power. The effects of the galvanic current are physic, chemic, and physiologic. Heat, light, sound, and mechanic motion may be produced by a sufficiently strong current. One of the most in- teresting of chemic effects is that of electrolysis, or decompo- sition of a substance (usually in solution) into its elements. Water, for instance, is broken up into hydrogen and oxygen. When a salt is electrolyzed the metal, or alkaline part, or cation, collects on the negative platinum pole; and the nega- tive, or acid part, or anion, at the positive pole. This fact is made use of in gilding, electroplating, and electrotyping. In the two former processes the object to be coated is suspended from the pole of a battery, while a piece of the metal desired is attached to the + pole, both being immersed in the plating fluid, usually a solution of the cyanid of the metal in question. When the current is set in operation the 50 MEDICAL PHYSICS. dissolved substance is decomposed, with deposition of the gold, silver, or nickel on the object attached to the pole. Electrotypes are made much as follows: An impression is made with the lines of type in melted wax, which is then coated over with powdered graphite. The mold is then suspended from the pole in an acid bath of cupric sulphate, containing also a copper plate hanging from the + Pl e - The passage of the current acts in the same manner as for electroplating. The process of photogravure also depends on electrolysis and on the fact that potassium dichromate in a gelatin film is not soluble after being acted upon by light. Fig. 17. Electrolysis. Experiment. Decompose potassium iodid solution containing a little boiled starch by means of electrolysis. Note the blue color pro- duced by the action of free iodin on the starch. Experiment. Make a "tin tree" by electrolysis, using a solution of stannous chlorid acidulated with hydrochloric acid. On which pole do the tin crystals collect? The galvanic, or constant current, as it is often called, is much used in medicine, especially to stimulate and exercise by contractions paralyzed muscles, in this way preventing atrophy until Nature restores the nervous connections. Electrotonus is the name applied to the increase of the normal nerve-current induced by the passage of a galvanic current along the nerve. ELECTRICITY. 51 Both the normal nerve-current and the electrotonic condition are shown by the galvanoscope or galvanometer (milliampere- meter). In electrotonus the excitability of the nerve in the neighborhood of the positive pole is decreased (anelectrotonus), whereas at the negative pole it is augmented (catelectrotonus). Hence, if an excitant action is desired the cathode is placed over the part; if a sedative, the anode is applied. The electric reaction of the nerves (and the muscles they supply) originating at or below a spinal lesion is rapidly dimin- ished and soon lost from degeneration due to trophic changes. In central, or brain, paralysis, on the other hand, the response of the nerves and muscles on the paralyzed side is not less marked than on the sound side. Normally the greatest effect is elicited on cathodic closing and anodic opening of the cir- cuit, but in the degenerative condition just mentioned the op- posite phenomena obtain: i.e., the contractions are greatest on anodic closing and cathodic opening. Such an alteration is termed the reaction of degeneration. In employing the constant current for a stimulant effect on muscles and nerves it is customary to lessen resistance by using a rather large sponge electrode moistened with water or brine. The sponge is used dry when the stimulus is to be con- fined to the skin. This current has no effect, except elec- trolysis, in the period between the make and the break. It should be turned on gradually to the required dosage; the seance may last from one to ten minutes, and then the current should be turned off slowly, thus avoiding annoying shock to the patient. Four hundred volts may kill an animal by the muscular contractions generating a large amount of heat. Sev- eral thousand volts may produce fatal shock (electrocution). Another common medical use of galvanism is for its elec- trolytic effect in resolving tumors, strictures, etc. For this purpose a suitable metallic electrode attached to the pole is employed. If a drying action is desired, as in the case of an unhealthy ulcer, the electrode should connect with the -f- pole, around which the negative, or acid, substances congregate. Epilation, or the permanent removal of hair, by electricity is an example of electrolysis, the needle used to pierce the hair- follicle being attached to the cathode. Cataphoresis, or the forcing of medicaments into the tissues by means of the con- stant current, is but seldom employed, having little, if any, advantage over the ordinary methods of administering medi- "cines. Electrocauterization is of great service in the treatment of diseased mucous membranes. For cautery effects the storage or secondary battery is usually selected, on account of the 52 MEDICAL PHYSICS. greater intensity of its current; and the electrodes are of plati- num, because of its resistance and infusibility. Sinusoidal alternating currents produce no chemic effects, and each wave moves in the opposite direction to the pre- ceding one. By its frequency is meant the number of waves per second. Periods are double waves: two in opposite direc- tions. Sinusoidal currents of considerable potency and a frequency of 100 to 200 per second give rise to serious and even fatal accidents, and are used for electrocutions. If the potential is increased and the frequency reaches several hun- dred millions or several billions, whatever the voltage the cur- rent becomes harmless. This strange fact is comparable with the fact that sound affects the organ of hearing and light that of sight only within certain limits of vibrations. Frictional electricity travels at the rate of 288,000 miles per second. In practice the galvanic-current velocity depends largely on the length of the circuit and the character and area of the conductor. Nerve-currents move at the rate of only 35 to 100 meters per second. Thermo-electricity is generated by heat in conductors of relatively small caliber or in obstructed conductors. While this form of electricity may be produced in a single metal, it is customary to solder together one end of bars of two metals, heating the bars at their junction. The thermo-electric pile consists of 49 pairs of bismuth and antimony bars arranged in 7 rows. The thermo-electric current is feeble, though steady and convenient. Other piles are made of 70 or more pairs of iron and type-metal, or of iron and galena. A new and cheap method of producing electricity is that of Dr. Jacques, who kept carbon plates in fused sodium hy- drate at 300, with the result that 32 per cent, of the carbon was converted into the electric current. Vital electricity is possessed by plants as well as animals. The most striking example of animal electricity is the Gym- notus, or electric eel of South America, which is said to give shocks so strong as to stun horses and cattle. Its electric apparatus consists of a series of prismatic tubes filled with an albuminous liquid, arranged along the sides of the body and connected with a special lobe of the brain. The strength of a series of discharges of vital electricity gradually lessens from first to last. Animal electricity is mainly, if not wholly, of the static variety, usually positive. MAGNETISM. 53 MAGNETISM AND ELECTROMAGNETISM. Magnetism is the property of attraction or repulsion of masses of like elements, exhibited especially by iron, nickel, and cobalt. It is a molecular force related to electricity. The natural magnet, or lodestone, is an oxid of iron, which was first found in Magnesia, Asia Minor; hence the name of magnet. Artificial magnets are made by rubbing with the lode- stone or with other artificial magnets, or by induction from the electric current through a coil of wire. Temporary mag- nets, like that of the faradic battery, are composed of soft iron; permanent magnets retain the power of attraction for a long time, and are made of tempered steel. Artificial mag- nets are of two forms: the bar and the horseshoe. The latter is generally employed. When not in use its armature, or keeper, should always be applied to prevent the escape of mag- netism. Compound magnets are composed of thin sheets of steel screwed together; they are stronger than simple ones. The property of magnetism is lost at a red heat. Experiment. Show the action of a bar magnet on iron filings placed on the other side of a sheet of paper and of a piece of glass, proving that magnetism does not require the presence of air. Sift the filings on the paper and show how the lines of magnetic force radiate in all directions. The two ends of a magnet are called its poles. No matter how small the magnet or into how many pieces it may be broken, each fragment has still two poles. When a magnet is freely suspended, one end, or pole, always points toward the north; the other, to the south. A needle magnet balanced over a circular chart constitutes the mariner's compass. Experiment. With a bar magnet and a compass show how like poles repel and unlike attract. The earth itself is a great magnet, its magnetism being due probably to electric currents flowing from east to west and generated by the sun's rays (sun-spots, northern lights). The magnetic poles of the earth do not correspond with the geo- graphic poles. The north magnetic pole is in Boothia Land in 70 north latitude; the south pole in Victoria Land, 75 1 / 2 south latitude. The longitude of these poles shifts from east to west and back again, the oscillation requiring centuries for its completion. At present the north magnetic pole is moving westward at the rate of 1 in twelve years. From these facts it is evident that the north pole of the compass points directly 54 MEDICAL PHYSICS. north only in the meridian which passes through the north magnetic pole. This meridian is known as the line of no variation. The "dipping" of the needle from the horizontal increases as we approach the magnetic pole,, where it would stand vertical were it not counterpoised by a weight at the opposite pole. The dual nature of magnetism is designated by the term polarity. Substances, like iron, that are attracted by the mag- net and arrange themselves axially between its poles, are called paramagnetic. Those which are repelled and take an equatorial position between the poles are termed diamagnetic. Bismuth is the foremost example of this class. All substances in the form of heated gas are diamagnetic. Besides the compass, the chief applications of permanent magnets are in removing pieces of iron or steel from the eye, in separating magnetite from sand and crushed rock, and in freeing malt and grain from pieces of scrap-iron. Soft mag- nets are employed very extensively in faradic batteries and electric dynamos. Literally, animal magnetism does not exist. ELECTROMAGNETISM, OR ELECTRODYNAMICS. When a bar magnet is placed within a coil of wire it sets up a current of electricity in the coil, and when the magnet is removed there is a current in the opposite direction to the first. Conversely, when a piece of soft iron is placed within a coil through which a current of electricity is passing, the iron becomes magnetic. When one coil is placed within or without another through which a current is passing, a sec- ondary or induced current is produced in the former: in the opposite direction at the make of the primary or battery cur- rent, in the same direction at the break. In practice the pri- mary helix, or coil, is made short and thick, so as to offer as little resistance as possible to the electric flow. The secondary coil, on the other hand, should consist of a long, thin wire, since, the longer and thinner it is, the greater the induction. Both coils, of course, should be carefully insulated. Experiment. Show magnetic induction with iron tacks and mag- nets: how one tack attached to the magnet can be made to pick up another. The Euhmkorff induction-coil consists essentially of a gal- vanic battery with its connecting wires, a secondary helix, a soft magnet, a spring interrupter, and a condenser. The best coils give a spark, at the break, several feet in length. The ELECTROMAGNETISM. 55 faradic battery is the same as a Ruhmkorff coil minus the con- denser. The draw-tube in the battery is placed between the primary and the secondary coils, and when drawn out increases the current by removing obstruction to induction. The two faradic currents (primary and secondary) are also known as interrupted currents. The secondary, or induced, current, is stronger than the primary, or battery, current. Either current is much more intense at the break than at the make of the circuit, since at the break the extra current set up by induction between adjacent turns of the same coil runs in the same direction as the principal current, while at the make it goes against the main current and reduces its force. As a nerve-stimulant and muscle-tonic the interrupted cur- rent is preferred in most instances to the constant current. Galvanism, however, has a deeper effect than faradism, and hence is employed in the treatment of internal organs and the stimulation of paralyzed muscles that do not react to the faradic flow. The passage of electricity from a Ruhmkorff coil through vacuum apparatus, such as Crookes's tubes, gives rise to a brilliant display of violet-tinted light, which is accompanied by the invisible x- or Roentgen rays, both the latter and the former emanating from the cathode. The x-rays are peculiar in that they penetrate many objects opaque to ordinary light, such as wood, paper, and flesh. On the other hand, they do not pass through glass. It is easy to comprehend how they may be made to form a shadow, or silhouette, of bodies opaque to themselves on a sensitized plate, which may be developed as any other photographic negative. Sciagraphy, or shadow-pict- uring, has already proved of much service in the diagnosis of bony injuries and the localization of foreign bodies in the tissues. The fluoroscope does away with the necessity of pho- tographic methods in connection with the x-rays. It consists, in the main, of a sheet of pasteboard coated with some fluores- cent material (platino-barium cyanid or tungstate of calcium), which reveals directly to the observer's eyes the shadow of the skeleton or of foreign bodies imbedded in the flesh. The electric dynamo is the basis of nearly all the practical industrial applications of electricity. It consists of a revolv- ing electromagnet, or armature; and a fixed, or field, magnet. Traces of magnetism in the latter induce slight currents in the armature, and, by reaction between the two, currents of great strength are soon produced. The alternating currents may be turned in one direction by a simple contrivance called a. pole-changer, or commutator. The currents thus produced 56 MEDICAL PHYSICS. pass over conducting-wires to be transformed as desired into heat, light, sound, and mechanic motion. The electric motor is, practically speaking, the same as the dynamo. The move- ment of the armature is easily transmitted to the wheels of cars and machinery. "Fusible wires' 7 of alloys that melt at a low temperature are often introduced into buildings to prevent fires from excessive currents of electricity. Electric lighting depends on the resistance to the passage of electricity through a poor conductor or one of small caliber. The incandescent lamps are exhausted of air and contain a filament of carbon. The arc light is produced by the resistance of the air to the current passing between two adjacent elec- trodes. As most metals melt quickly in this terrific heat, the nearly infusible gas-carbon is employed for the electrodes, the sticks being kept at the proper distance as the -f- pole wastes away, by an automatic feeding arrangement. Electric light is Fig. 18. Telephone. most like sunlight of any artificial product, and is also the most hygienic. It is quite rich in violet and actinic rays. Electric heating, like electric lighting, depends on the re- sistance of poor conductors. Electric furnaces yield a very intense heat, which is used for fusing metals and for reduction purposes, as in the extraction of aluminum. Welding of the common metals is done now very extensively by electricity. A new suggestion in this connection is the electric pad, or permanent poultice, through which a constant current is made to pass. The electric current has many applications in apparatuses of speech and sound, as exemplified by the telephone, the mi- crophone, the telegraph, the telautograph, and electric bells, clocks, and fire-alarms. In each of these we have a combina- tion of electricity and magnetism. In the telephone, for in- stance, the vibrations of the thin diaphragm at the bottom of ELECTROMAGNETISM. 57 the speaking-tube set in motion by the speaker's voice reacts on the bar magnet behind,, and this, in turn, induces variable currents in the surrounding coil of wire. These currents trav- erse the wire to the connected instrument at a distance, where the series of changes is reversed: i.e., the magnet is affected by the current in the coil of wire, and the metallic disk of the receiver is magnetized and drawn nearer and let go accord- ingly. For practical use each instrument contains a Leclanche cell (ammonium chlorid), or a dry cell, furnishing a constant current which the action of the vibrating disk on the magnet merely modifies. For long-distance conversations, as between different cities, powerful induction-coils are employed to fur- nish the current. In the telegraph (Morse, 1837) pressing the key at one office closes the circuit. When the finger is removed a spring pulls the key up. In the receiving office when the circuit is closed the key here is magnetized and drawn down upon the sounder; when the circuit is broken it springs up again, and thus the succession of clicks, or dots and dashes as shown on paper, is repeated by the instrument receiving the message. The earth itself is the best conductor of electricity, so that one line of wire is made to suffice for telegraphic communica- tion, the wire being grounded at either terminus. In trans- mitting messages long distances the strength of the current is diminished so much that it is unable to move the sounder audibly. This difficulty is overcome by means of repeaters or relays, electromagnets wound with long, thin wire, used to close the circuit of the local battery. Wireless telegraphy de- pends on the Hertzian waves of ether, or high-potential elec- tricity. The apparatus consists of a vertical insulated wire; a transmitter, including a Euhmkorff coil and two sparking rods with a brass ball; and, last, a receiver composed of two silver plugs in a glass tube, along with a mixture of nickel and silver filings. Electric bells, clocks, and fire-alarms act by the induction of a closed circuit on a soft magnet, which, in turn, sets in motion wheels, hands, or striking-springs. The so-called electric belts, brushes, clothing, etc., are utterly useless and worthless. Obviously even theoretically they can return to the body only the electricity they have derived from it by simple friction or by a slight chemic action with the acid perspiration. Experiment. Put a coin below the tongue and a piece of zinc above. Note sharp twinge and metallic taste when the two touch. 58 MEDICAL PHYSICS. CRYSTALLOGRAPHY. Most inorganic and many organic substances when assum- ing the solid state from fusion, solution, or sublimation tend to take on a symmetric geometric, or crystalline, form. The liquid and gaseous states aid crystallization by allowing the molecules to arrange themselves in order around the axes or lines of growth: i.e., certain imaginary lines in which cohesive force is greatest. Crystals by fusion are said to be formed in the dry way; when from solution, in the moist way. The largest and most perfect crystals are those produced by Nature in the gradual evaporation of aqueous solutions of mineral salts. The process of crystallization can be hastened by im- mersing in the liquid strings, chips, and other foreign objects to serve as nuclei of growth. Kock-candy and milk-sugar are prepared in this manner. Experiment. Make a saturated solution of alum, and hang in it a piece of twine. When the liquid has cooled the excess of siibstance above its solvent power at the lower temperature will be found as crystals on the cord. The formation of the beautiful frost patterns on the windows in winter is another illustration of the same facts. The forms of crystalline matter are quite numerous, yet they can be classified in six simple systems, namely: the monometric, dimetric, trimetric, monoclinic, triclinic, and hexagonal. The monometric (regular, isometric) system has three axes which are equal in length and at right angles to each other. The primary type of this system is the cube, exem- plified by iron pyrites. The regular octahedron (magnetite, diamond) and regular pyramid, or tetrahedron (fluorspar, tetrahedrite), are derived from the cube by truncation of its solid angles. The dimetric, or tetragonal, system has also three axes at right angles to each other, but one of them is shorter than the other two. The two types of this system are the square pyramid, or acute octahedron (octahedrite), and the square prism or column (wernerite). In the trimetric, or orthorhombic, system the three axes are perpendicular to each other, but are all of unequal length. The varieties are the rhombic and rectangular prisms and pyramids. Examples of substances belonging to this system are sulphur (rhombic octahedron), topaz (right rhombic prism), and andalusite (right rectangular prism). The monoclinic, or oblique, system has three unequal axes, like the trimetric system, from which it differs by the CRYSTALLOGRAPHY. 59 vcrtic axis being set obliquely to the other two, instead of perpendicularly. The oblique pyramid (feldspar) and prism (orthoclase, rectangular; titanite, rhombic) are the subdivis- ions. The triclinic, or doubly oblique, system has three axes no two of which are at right angles to each other. The doubly oblique pyramid (copper sulphate), doubly oblique prism (chal- canthite), and doubly oblique octahedron (axinite) illustrate this system. The hexagonal, or rhombohedral, system has four axes, three of which are in the same plane at angles of 60 with each other; the fourth is perpendicular to the other three. The Fig. 19. Systems of Crystallization. hexagonal prism (apatite) is the primary form. From it the hexagonal pyramid (quartz) is obtained by truncation of the angles of one end; the rhombohedron, or scalenohedron (cal- cite), by truncation of the alternate angles of either end. When two substances crystallize in the same form they are said to be isomorphous. Potassium iodid and sodium chlorid, for instance, both crystallize as cubes. Isomorphous compounds frequently contain the same number of atoms. A substance which crystallizes in two or more systems is termed dimorphous or polymorphous. Sulphur is dimorphous (rhombic octahedron and monoclinic prisms). Non-crystalline substances are called amorphous: that is, without definite form. An allotropic ele- 60 MEDICAL PHYSICS. ment is one that exists in two or more crystalline or amorphous states, each with different physic properties. Carbon, for ex- ample, is met with as charcoal, plumbago, and diamond. A characteristic of many crystalline rocks is that of cleav- age, which means the property of splitting readily in one direc- tion into natural layers. Mica furnishes a good example of this peculiarity. The greater number of crystalline substances are combined chemically with water, termed the water of crystallization; and to this the various colors of most crystals are due. The com- bination may be molecule for molecule, that is, one of water to one of the solid substance; oftener, however, the water- molecules much exceed in number those of the mineral matter. Alum, for example, has 24 molecules of water to 1 of the salt proper. A few compounds, as silver nitrate, crystallize with- out any water in their composition; hence are called anhydrous. Some substances take up more or fewer molecules of water of crystallization according as the process is conducted at a lower or higher temperature; the resulting crystals in such an event often differ from each other in size and shape. Sodium car- bonate crystallizes at ordinary temperatures with 10 molecules of water in oblique rhombic prisms; at higher temperatures with 8 or 5 of water; from boiling solutions as rectangular plates with 1 of water. The chemic union between the water of crystallization and the remainder of the crystal is a very weak one, and is broken up in most instances by heating the crystals to the b.p. of water. Experiment. Heat a crystal of copper sulphate carefully in a porcelain dish, and note disappearance of color along with the water of crystallization. Continue the heating until a dry white powder is left and allow to cool. Then place the powder in the palm and add a little cold water. The blue color is restored, and considerable heat is produced (chemic action). Some crystalline drugs (sodium compounds) lose their water of crystallization gradually on simple exposure to dry air. These bodies are designated as efflorescent. On the difference in solubility, and hence the temperature at which crystalline solidification takes place, depends the separation of substances by fractional crystallization, the least soluble substance crystallizing first out of the cooling or con- centrating solution. In this way common salt is prepared from sea-water, the more soluble salts remaining in solution in the mother-liquor, or bittern. Another use of crystallization is in purifying medicines, as foreign matters are dissociated to a large degree during the OSMOSIS AND DIALYSIS. 61 formation of crystals. Hence, ice is purer than the water from which it was formed. In chemic microscopy the ability to rec- ognize the crystalline forms characteristic of various compounds is of the greatest practical importance. OSMOSIS AND DIALYSIS. Osmosis signifies the stream of water-molecules passing through a membrane; dialysis, the passage of the molecules of a dissolved substance. When pure water and an aqueous solution of a salt are separated by a semipermeable membrane (one which allows water, but not the salt, to pass, such as finely-divided potassium ferrocyanid deposited in fine-grained porcelain), the osmotic pressure is greater toward the side of the salt solution, the dissolved molecules of the salt seeming in a manner to screen the membrane from contact with a cer- tain number of water-molecules. The osmotic pressure varies directly with the concentration of the solution (molecules or ions), and the highest hydrostatic pressure thus exerted has been proved equal to that caused by as many molecules of gas as in that of the crystalloid in solution, if confined in the same space at the same temperature. Solutions of substances con- taining the same number of molecules and ions in a given volume exert the same osmotic pressure, and are said to be isohydric. Most inorganic substances when in solution break up or dissociate into two or more parts known as ions, and, the greater the dilution, the more complete the dissociation (quite complete at about Viooo normal). Such substances are called electrolytes. Thus, sodium chlorid dissolved in water disso- ciates more or less into the positively charged cation sodium and the negatively charged anion chlorin. Sugar, on the other hand, though soluble and crystalloid, is a non-electrolyte. The liberated ions are charged with electricity, and it is they that carry the current from plate to plate. In osmotic pressure ions are of equal value to molecules; hence, the more the dis- sociation, the greater the pressure. The osmotic pressure of non-electrolytes in solution is readily calculated by comparing gram-molecular solutions (con- taining the molecular weight of the substance in grams per liter) with the pressure required to compress the gram-mole- cule of hydrogen (2) to a liter. Thus, a gram-molecular solu- tion of cane-sugar contains 342 gm. per liter, and it contains as many molecules as 2 gm. of hydrogen. Now, 1 gm. of hydrogen at the pressure of 1 atmosphere (760 mm. of mer- 62 MEDICAL PHYSICS. cury) occupies a volume of 11.16 liters; hence 2 gm. occupy twice this volume, or 22.32 liters. To compress the latter volume to a liter requires a pressure of 22.32 atmospheres. A gram-molecular solution of cane-sugar (or any other non- electrolyte) would therefore exert an osmotic pressure of 22.32 atmospheres; a 10-per-cent. solution, y io of 22.32, or 2.23 atmospheres (1694.8 mm. of mercury). In calculating the osmotic pressure of electrolytes by this method one would need to know what proportion of the substance in solution had dis- sociated into ions. In the case of electrolytes a very convenient method of determining osmotic pressure is by means of the f.p. As already stated, this is lowered by the presence of salts in solu- tion, and the lowering has been proved to be proportional to the number of molecules and ions in a given volume: a fact which holds good as well with osmotic pressure. The amount of depression in centigrade degrees and fractions below the f.p. of pure water is ascertained by means of a delicate dif- ferential thermometer, and is usually expressed by the symbol A. A gram-molecular solution of any non-electrolyte lowers the f.p. 1.87 C.; hence the osmotic pressure of a given solu- tion can be expressed directly by dividing the constant 1.87 into the A of latter. Thus, the A of blood-serum is 0.56; this divided by 1.87 gives 0.3; and 0.3 of 22.32 = 6.696 atmos- pheres, the equivalent of the osmotic pressure of blood-serum. From the physic standpoint an isotonic or isomotic solu- tion is one having an osmotic pressure equal to that of blood- serum 0.95-per-cent. common salt, for instance; a hypertonic solution exerts a higher, and a hypotonic solution a lower, pressure than does serum. The great difference in the rate of membranous diffusion of crystalloids and colloids makes the separation of one class from the other an easy matter. The dialyzer, an instrument for this purpose, consists of a round glass vessel open at the upper and narrower end, and closed at the bottom with a piece of parchment-paper. The mixed solution is placed in the dia- lyzer, and the whole immersed to a slight depth in distilled water for 12 or 24 hours. At the end of this time the crystal- loid substance will be found, for the most part, in the water exterior to the vessel, while the colloid material still remains within. A few amorphous substances (peptons) are crystalloid. The process of dialysis is of greatest service in toxicology, in the separation of crystalloid poisons from food and other stomach-contents. It is also used to some extent in the prepa- ration of drugs. SOUND. 63 Experiment. Place a copper sulphate solution and some white of egg into a dialyzer, and let stand until the next day. The blue color of the copper salt now shows without as well as within the vessel, but the albumin has not diffused: the liquid within the vessel coagulates on boiling, while that without does so hardly at all. SOUND. Sound consists in vibrations of the air or of sonorous (elastic) substances perceptible to the sense of hearing. The science of sounds is known as acoustics. Experiment. Fit a large test-tube with a tight cork fitted with a short-pointed glass tube. Place a few granules of zinc in the bottom of the test-tube, and cover them with an inch or two of dilute sulphuric acid. The gas hydrogen is evolved. After a few minutes, when all the contained air has escaped, light the gas, and hold the flame in the mouth of a glass cylinder about an inch wide. On adjusting the flame to the right point in the tube a loud tone is produced by the vibrations of heated air in the cylinder. Sounds can also be produced by an inter- mittent beam of sunlight playing on colored worsted or lamp-black in a glass tube. Experiment. Place a watch on cotton-wool under the air-pump, and create a vacuum. The ticking becomes fainter, and is finally im- perceptible. Sound is transmitted by spheric waves or undulations, at the rate in air of about 1 /. mile per second (1125 feet at 60 F.); in water 4 times as fast; in iron 16 times as fast. In gases the velocity of sound varies as the square root of elas- ticity and inversely as the square root of density. A wave- length is the distance between any point on a wave and a similar point on the wave before or behind it. The amplitude of vibration is the greatest distance traversed by a particle in either direction from a median position; that is, a wave-height. Musical notes are produced by repeated, rapid, regular vibra- tions; noise by a single short sound or a confused and irregular mixture of sounds. Loudness, or intensity, varies inversely as the square of the distance and directly with the square of the amplitude of the vibrations; also with the density of the medium and at- mospheric motion. It is increased by reflection from a neigh- boring sonorous body, such as a sounding-board, or from the walls of a room (resonance), and is maintained for long dis- tances in straight, cylindric tubes (speaking-tubes). Echoes are the result of reflection forming return-waves. In sound, as in other forces, the angle of reflection equals the angle of incidence. Sound is also refracted by passing through media of differing densities. 64 MEDICAL PHYSICS. Pitch depends upon the number of vibrations per second. The limit of perceptible sounds is from 16 per second for deep sounds, to 40,000 per second for high sounds. The human voice ranges from 100 to 1000 vibrations per second. Vibra- tion-frequency in pipes varies inversely as the length; open pipes are twice as long as closed pipes of the same pitch. The vibration-frequency of strings of the same material varies in- versely as the length and the square root of the weights, and directly as the square root of the tension. The siren is an in- strument for the determination of vibration-frequency. Middle C has 256 or 264 vibrations per second. Each octave contains double the number of vibrations of the one just below it, and one-half of that above. If the ratio of in- tervals of three notes is 4:5:6 they form a harmonic triad. If to these three a fourth note, the octave of the first one, is added, we have a major chord. In a minor chord the ratio is 10:12:15, with the octave of the first note. Quality, or timbre, varies with the nature of sound-producing bodies, and depends on the form of vibrations due to the combination with funda- mental tones of harmonics or overtones: i.e., the sounds pro- duced by the vibration of an instrument in parts. The musical scale is made up of gamuts or series of notes connecting octaves. These notes are represented by the letters C, D, E, F, G, A, and B. If the vibrations of C be represented by 1, those of D are 9 / 8 ; of E, 5 / 4 ; of F, */; G, V 2 ; A, 5 / 3 ; B, 15 / 8 ; and the octave C, 2. The larger intervals ( 9 / 8 and 10 /o) between these notes, obtained by dividing the larger frac- tions by the smaller, are termed tones; the smaller interval ( 16 / 15 ), semitones. Interference of sounds may intensify or nullify motion, according as the hollow of one wave fits in the hollow or the crest of another. The wavy sounds produced by interference are called beats; the number per second from two simple notes equals the difference of their vibration-numbers. Interference in .cords commonly results in vibrations in loops or segments: the points of least vibration are called nodes; the points of greatest motion, antinodes. Sympathetic vibrations are those produced in a body by the vibrations of another body near by. They are termed forced vibrations when the body acted on was already in vibration, but was made to assume the vibra- tion-period of the other. The ear, or organ of hearing, is designed to gather and convey sound-waves by vibrations of the tympanum and the chain of bones in the middle ear, to the vestibule and cochlea of the inner ear. The organ of Corti consists of about 3000 SOUND. 65 minute bristles of various lengths, suspended in the liquid here; they "take up and analyze the vibrations, much as when we sing into a piano with the damper down, only those strings respond which are in unison with the sound produced by the voice." These bristles are connected with nerve-filaments, which transmit the sensory impressions to the auditory center of the brain. The larynx, or voice-box, is "a reed-instrument situated at the top of the windpipe, or trachea." The elastic vocal chords are stretched across the orifice: laxly when breathing, more tightly during vocal action. Tension is regulated by muscular action, and, the tenser the cords, the higher the pitch. The mouth and nasal passages serve as resonators, and change shape in accordance with vocalization and articulation. "Chest-notes" are produced by vibration of vocal cords as a whole; falsetto notes by vibration of the free edges. Two octaves is the average extent of scale of the human voice. The wave-length of voice in women during ordinary conversation is 2 to 4 feet; in men, 8 to 12 feet. The tuning-fork is an instrument much used in the dif- ferential diagnosis of ear-troubles. In testing bone-conduction it is placed with the end of the handle resting at a right angle on the mastoid or vertex. Air-conduction is normally superior to bone-conduction, and the fork held before the meatus should be heard twice as long as on the mastoid; or if the vibration ceases to be audible on the bone it should still be heard at the orifice of the auditory canal. When the fork is heard longer by bone-conduction, the canal or the middle ear is affected. In labyrinthine disease the impairment of hearing is the same for air- and for bone- conduction. The phonograph consists essentially of a metal cylinder rotated by a crank and covered with wax or tin-foil and threaded like a screw; over the furrow is set a vibrator",' style at the bottom of the mouth-piece. Every movement of the style caused by the voice is thus recorded by impressions in the foil, and if the cylinder is brought back to its original position and turned as before, the style will play up and down over the depressions and ridges, and so repeat the spoken words. The audiphone is a fan-shaped sheet of ebonite or elastic card-board held between the teeth of persons partially deaf, to aid them in hearing. 66 MEDICAL PHYSICS. QUESTIONS ON MEDICAL PHYSICS. 1. Mention a form of matter perceived by smell, but not by sight; one recognized by feeling, and not by sight. 2. Distinguish between a physic and a chemic change, and men- tion an example of each. 3. Distinguish between volume, mass, and density. 4. Name the three chief metric units, and explain their mutual relations. 5. Read the following: 0.025 m.; 25.365 gm. 6. Write as one number 1 kg. and 1 mg. 7. How many grams in a dram? In an ounce? 8. What is the length in English measure of a meter? Of a millimeter? Of a micromillimeter? 9. What is the capacity in English measure of a liter? 10. How many milligrams in a kilogram? 11. Write a metric prescription for a 2-ounce mixture, teaspoonful doses, using the following drugs and doses: Potassium acetate, gr. x; salicylic acid, gr. xx; water, to fill the bottle. 12. What difference between a Troy, or apothecary's, ounce and an avoirdupois ounce? Same as to pound? 13. Does a pint of water weigh a pound? 14. What difference, if any, between a minim and a drop? 15. How many grains of corrosive sublimate to the pint of water in making a 1 to 1000 solution? 16. A 4-per-cent. solution of cocain contains how many grains to the ounce? 17. How do high altitudes mechanically help weak lungs? 18. What is the use of the neck of a pitcher? 19. If a body is of the same sp. gr. as water, where does it float? 20. Is the sp. gr. of water at ordinary temperature below or above 1? 21. What effect does the addition of water to alcohol have on the sp. gr. of the latter? 22. A piece of brass weighs 37.71 gm. in air, 32.21 in water. Find its sp. gr. 23. A piece of metal weighs 40 gm. in air, and displaces a trifle more than 2 c.c. of water. What is the approximate sp. gr. of the body, and of what metal is it composed? (See table.) 24. The sp. gr. of caustic potash is 2.1. About what is the sp. gr. of a 10-per-cent. solution in water? 25. W 7 hat is the approximate strength of a solution of dilute sul- phuric acid (sp. gr., 1.40) ? 26. Why are gases more compressible than liquids or solids? 27. What is the sp. gr. of a lump of sugar weighing 20 gm. in air and 9 gm. in oil of turpentine (sp. gr., 0.865) ? 28. Why is water stale after boiling? 29. Why is it difficult to push an inverted tumbler directly down- ward into a vessel of water? 30. Why does a string attached to and capable of holding up a weight break suddenly when jerked? (Fractures of the patella and other bones have been caused by muscular action.) 31. Why do bubbles appear on a glass plate immersed in water? 32. Why does quicksilver not wet the fingers? 33. Give an example of each of the four kinds of elasticity. 34. Why are cables stronger than chains of the same size? QUESTIONS. 67 35. What difference in weighing with scales at sea-level and at high altitudes? 36. What is the volume of a liter of hydrogen (at ordinary pressure) when subjected to a pressure of 100 atmospheres? 37. Twelve liters of oxygen at standard temperature and pressure undergo what change in volume at a temperature of 60 C. and a pressure one-fourth less? (12.000 X 333 / 2 7 3 X 700 / B 7 .) 38. Oxygen is 16 times as dense as hydrogen. What is their diffusion-ratio ? 39. Explain nose-bleed on ascending high mountains. 40. Explain the weather-changes of the barometer. 41. What is the siphonage-force in grams of a siphon 2 cm. in caliber, the long-arm sine being 40 cm. and the sine of the short arm 15 cm.? 42. How does charcoal act as a deodorizer? 43. Why is it easier to descend the stairs than to ascend them? 44. Define and give an illustration of the principle of the correla- tion and conservation of energy. 45. Explain the relationships of heat, light, and electricity. 46. Why do people in warm countries wear light-colored clothing? 47. Why do muddy roads dry more quickly in windy weather? 48. What time of day, as a rule, is the relative humidity of the atmosphere greatest? 49. Why does the wind often go down with the sun? 50. Why is it more often cloudy morning and evening than in the middle of the day? 51. Contrast the direction of the air-currents at the top and the bottom of an outside door in winter and in summer. 52. Why is frost more likely to be seen after a clear than a cloudy night? 53. Why is mercury preferred to water for thermometers and barometers? 54. State the normal temperature of the human body (mouth) in F. and in C. readings. 55. Change 40 F. to the centigrade scale. 56. Why are the rails on a railway not joined together more closely? The height of Eiffel's tower (989 feet) varies 8 inches during the year. 57. The altitude of Denver is exactly one mile. What is the b.p. (centigrade) of water here? 58. Which has the higher b.p., fresh water or sea-water? 59. Which warms more quickly, ice or water? 60. Why is damp cold more chilling than dry cold? 61. How distinguish between a physic and a chemic solution? 62. Name a solid substance which aids in the solution of another. 63. Why is sterilization of surgical supplies more effective with steam heat than with dry heat? 64. If we mix a pound of water at 80 with another pound at 0, what is the temperature of the mixture? Suppose, in the second case, we use a pound of snow or ice, what then? 65. How many pounds of water would a pound of steam (at 100) raise from the f.p. to the b.p.? 66. Which would be more affected by sudden thermal changes, a roughly-finished or a highly-polished dental filling? 67. What causes borax and many other salts to swell upon heat- ing? 68 MEDICAL PHYSICS. 68. What is the temperature of water at the bottom of a pond in winter? 69. Where is the warmest air in a room, and why? 70. Is the heat of the body mostly mechanic or chemic in origin? 71. Why are the nights comparatively cooler in dry, high climates? 72. Why do thick glass vessels break when suddenly heated or cooled? 73. Why not use alcohol for cleansing varnished surfaces? 74. Distinguish between deliquescence and efflorescence. 75. Explain steam-heating. 76. What liquid boils at about temperature of the body? 77. Why does early frost appear on some objects and not on others? 78. What causes "sweating" of ice-water pitchers? 79. Explain principle of glass hot-beds. 80. How does vinegar- or alcohol- sponging cool our bodies? 81. Why is our breath visible in winter? 82. Why is it nearly always cooler when the wind blows? 83. How is the straight rising of smoke a sign of fair weather? 84. Is more heat used up in melting ice or in boiling water? 85. Name the three forms of radiant energy. 86. Why cannot one see around a corner? 87. Explain, with diagrams, how a too great antero-posterior diameter of the eyes causes far-sight, and a too long diameter near- sight. (Rays of light are refracted by the crystalline lens, crossing each other a little behind the lens, so that the retinal image is an inverted one.) 88. How does polarized light differ from ordinary light? 89. What is the wavy motion seen around stoves in winter? 90. Why does a street appear to grow narrower farther away? 91. Why does the rising sun or moon look larger? 92. Name and explain the three kinds of spectra. 93. Why do electric cars run better in fair than in stormy weather? 94. Name and define the three chief units of current electricity. 95. Compare the electric resistance of the skin with that of the Atlantic cables. 96. Which electrode has a drying action, and which a softening effect, and why? 97. What causes the compass to point north and south? 98. Mention the chief differences between the galvanic and the faradic current. 99. Why does the faradic hand-cathode feel stronger than the anode ? 100. Why does acidulated water break up more easily by electrol- ysis than pure water does? 101. Distinguish between osmosis and dialysis. 102. Why do sodium chlorid solutions exert a greater osmotic pressure than an equivalent strength of a sugar solution? 103. What are isotonic, hypertonic, and hypotonic solutions? 104. Name the six systems of crystals, and mention an example under each. 105. To what is the color of most crystals due? 106. Why are sounds less intense on a mountain than in a valley? 107. How does a common cold change the voice? 108. If a flash of lightning is followed in five seconds by the thunder, what is the distance? QUESTIONS. 69 109. What are the three principal properties of sound, and on what e Ho 1 ^ ? does stoppage of the Eustachian tube cause partial temp Tn y H d o e w n d e is S tinguish between deafness due to external-, to mid- dle '' nlW 1 : dSSn?SSL heard better at night, and also often before a^ storm ?^ ear _ trmnpetSj stet hoscopes, and megaphones aid hear- ing! CHEMIC PHILOSOPHY. ELEMENTS. AN element is a substance composed of only one kind of matter. Iron, gold, hydrogen, and oxygen are elements. Chemic compounds are made up of more than one kind of matter. Water is a compound substance, since it can be de- composed by electrolysis into hydrogen and oxygen. There are about 80 elements known at the present time, 12 of which at ordinary temperatures are gases, 2 liquids, and the remainder solids. By far the greater number are metals; the non-metallic elements are often termed metalloids. The names of the ele- ments are generally Latin (end in urn], and indicate some peculiar or fancied property. Some of the well-known ele- ments have both an English and a Latin name; most of these were known to the ancients. The symbol, or sign, of an element is made up of the initial and sometimes another distinctive letter from the Latin name: e.g., C for carbon, Ca for calcium, Cl for chlorin, Cu for copper (Latin, cuprum), etc. TABLE OF ELEMENTS. NAME. SYMBOL. VALENCK. ATOMIC WEIGHT. USUAL POLARITY. Aluminum ... ... Al TV I A I _ VT \ 97 04 Antimony .... . . Sb m-y I 10 R Argentum (see "Silver "). Argon . - . A" -in 7 Arsenic . . . As mv 74 Q Aurum (see "Gold"). Barium Ba jj lQf{ q Be H Q AQ Bi mv OAQ q I Boron B III 10 Q T Br I III V VII 7q 7fj Cadmium ... Cd II ]11 5 _L Calcium Ca II 39 91 I , c IT IV nQ7 1 Cerium ... Ce II IV ( Ce vi ^ -|Qq q Cesium Cs I 132 7 1 Chlorin Cl I, III V VII 35 37 1 Chromium . . Cr IT iv (Cr vi ) ro n Cobalt Co II IV ( Co, VI ) 58 6 1 Columbium Cb v 93 7 r Cu ii (Cu ii ) fJQ 10 Cm (70) ELEMENTS. 71 TABLE OF ELEMENTS (Continued). NAME. SYMBOL. VALENCE. ATOMIC WEIGHT. USUAL POLARITY. Er II (Er, VI ) 166 _[- Ferrum (see "Iron"). F I 19.0 Gd 156.1 -f Ga III 69.9 4- Germanium Glucinum (see "Beryllium"), (jjold Ge Au II, IV I, III 72.3 196.7 + 4- Helium He Hydrargyrum (see "Mercury "). H I 1.0 4. In II (Il) 2 = VI ) 113.6 -f I I, III, V, VII 126.53 Ir II, IV, VI 192.5 4. Iron ... Kalium (see " Potassium "). Fe Kr ii, iv (Fe 2 vi ) 55.88 80.0 + La in 138.2 -h Lead Pb II, IV 206.4 Li i 7.01 -f Me ii 24.3 4- Mn i, iv(Mn 2 = vi) 54.8 + Ms 228.0 Mercury Hg (Hg, =ll), ii 199.8 -f 40.0 Molybdenum . Natrium (see "Sodium"). Neodymium Mo Nd II, IV, VI ii 95.9 140.5 4- Neon . . . Ne 22.0 Nickel . . Niobium (see "Columbium "). Nitrogen Ni N ii, iv (Ni 2 = vi) I III V 58.6 14.01 + Osmium Os II, IV, VI, VIII 190.3 4- Oxygen o II 15.96 Palladium Phosphorus . . ... Pd p II, IV III, V 106.35 30.96 + Platinum . . Pt II, IV 194.3 4- Plumbum (see "Lead"). K I 39.03 4- Praseodymium Pr II 143.5 4- Rhodium .... Rh II, IV 102.9 4- Rubidium Rb I 85.2 -j- Ruthenium Ru II, IV, VI, VIII 101.4 + Samarium . . . . Sm III V 149.6 4- So III 43.9 + Se II, IV, VI 78.9 Si II, IV 28.3 Silver Ag I 107.66 4- Sodium Stannum (see "Tin"). Na I 23.0 + CHEMIC PHILOSOPHY. TABLE OF ELEMENTS (Concluded). NAME. SYMBOL. VALENCE. ATOMIC WEIGHT. USUAL POLARITY. Stibium (see "Antimony"). Strontium Sr II IV 87 3 4. Sulphur . . S II IV VI 31 98 Tantalum Ta III V 182 Tellurium Te II, IV, VI 125 Terbium Tb III 159 1 4. Thallium Tl I III 203 7 4- Th IV 231 9 + Thulium Tu 170 7 -j- Tin Sn II, IV 118.8 4- Titanium , . Ti II IV 48 Tungsten W II IV VI 183 6 Uranium u ii, iv (Uo vi ) 238.8 4- Vanadium Wolfram ( see " Tungsten " ) . Ytterbium . V Yb III, V III 51.1 172 6 4. Yttrium .... Yt III 88 9 4. Zinc . . Zn II 65 1 4- Zirconium Xenon, Polonium, Radium, etc. Zr II, IV 90.4 + ATOMS AND THEIR PROPERTIES. An atom is the smallest indivisible particle of matter that can take part in a chemic change. Atoms do not usually exist separately, but are held together by chemism, or chemic affinity (polarity), so as to form molecules. A molecule may therefore be denned as the smallest portion of matter that can exist in a free state. When the constituent atoms of molecules are alike, we have a simple, or elemental, molecule; when the atoms are unlike, a compound molecule. Simple molecules make up elements; compound molecules, compound substances. An element in the free, nascent, unsaturated, or atomic state has a more powerful action on other substances than when in combination, since no force is spent in breaking up existing molecules. Free atoms have no polarity until they enter into combination. Labile chemic compounds are unstable bodies, and readily undergo chemic change: either a disruption of the molecule or a new intramolecular arrangement of atoms, which tend to migrate to a more stable position. The term stabile indicates the reverse of labile. Potential, or static, labile compounds include the explosives, such as nitroglycerin. Chemic changes ATOMS. 73 destroy static labile compounds, whereas dynamic, or kinetic, labile compounds pass into polymeric or isomeric compounds: i.e., the atoms take on a different arrangement within the molecule, or several like molecules are fused together into one. ATOMICITY. It has been determined by careful experiments that most elemental molecules are diatomic: i.e., they contain two atoms. Ilg, Cd, Zn, and Ba are monatomic; Se and (ozone), tri- atomic; As and P, tetratomic; S (below 550), hexatomic. Colloid molecules have more atoms than crystalloid; hence are larger. The physic properties of substances vary greatly ac- cording to the method of atomic linking, which in true chemic compounds is always an unbroken system. The different forms and properties which some elements assume according to the ways in which their constituent atoms face each other in the molecule, is termed allotropic. In chemic nomenclature the symbol of an element represents also one atom of the element. Experiment. If equal volumes of the two gases H and Cl are brought together in a glass vessel in the light, they quickly combine, forming hydrochloric acid gas, and the green color of the Cl is entirely lost. Now, according to Avogadro's law, each elemental gas contained the same number of elemental molecules; say, a billion. But the com- pound gas occupies the same space as both; hence it contains 2,000,000,- 000 molecules, each of which is made up of 1 atom of H and 1 atom of Cl. To furnish 1 atom to each compound molecule every simple mole- cule of H and of Cl must therefore consist of 2 atoms. In much the same way, by electric synthesis or analysis, it is readily proved that the molecule of water contains 2 atoms of H and 1 of O; and so on with other elements and compounds. ATOMIC WEIGHTS. The actual weight of the atom of any element is, of course, an imponderable quantity, but the relative weights of ele- mental atoms is easily determined by comparing the weights of equal volumes of these elemental substances in the gaseous state and at the same temperature and pressure, making due allowance for atomicity. The atomic weight of any element is the weight of an atom of the element as compared with the weight of an atom of H, taken as the unit, or 1. The atomic weight, for instance, of is approximately 16; of Br, 80; of Na, 23. The density, or relative mass, of an element is equiv- alent to the atomic weight, providing both elements compared have the same number of atoms to each molecule. For exam- 74 CHEMIC PHILOSOPHY. pie, and H both contain 2 atoms in the elemental molecule; hence the density of is 16. Hg, on the other hand, has an atomic weight of nearly 200, and contains only 1 atom to the molecule; its density is, therefore, one-half of 200, or 100. Briefly stated, the density is half the molecular weight, by which is meant the sum of the weights of all the atoms in a molecule. It is necessary to know the atomic weights of the different elements in making most chemic calculations. For most ordi- nary purposes fractions are disregarded and the nearest whole numbers employed. Atomic weights are inversely proportional to the specific heats of elements, or, in other words, the atoms of the various elements have equal capacities for heat. The product of the specific heat of any element by its atomic weight gives a nearly constant quantity: namely, 6.4. Elements of the same class vary in potency directly with their atomic weights; hence it is a law that "the properties of an element are a periodic function of its atomic weight/ 7 POLARITY. As already stated in the section on physics, when an elec- trolyte is decomposed by electrolysis, the metal or -f- element (cation) clings to the pole, while the element or part (anion) is set free at the + pole. Metals are, therefore, elec- tropositive in nature; metalloids, electronegative. Yet this classification is relative and a question of degree: some metals are more positive than others; some metalloids more negative than other non-metals. is the most of elements; Cs, the most -}-. The following short list, comprising the more common elements, represents this relationship, each element being + to the ones which precede and to those that follow: 0, S, 1ST, Cl, Br, I, P, As, B, C, Sb, Si, H, Au, Pt, Hg, Ag, Cu, Bi, Sn, Pb, Co, Ni, Fe, Mn, Ce, Al, Mg, Ca, Sr, Ba, Li, Na, K, Cs. In chemic compounds plus and minus elements are com- bined, and, the wider the difference in their polarity, the greater the attraction between them, and, generally speaking, the stronger the combination. Experiment. Cut a piece of the metal K, and note how quickly the cut surface whitens (oxidizes). When two elements of the same family are capable of combining directly with each other, the one having the highest atomic weight takes the positive role. H and B invariably VALENCE. 75 take the positive role in combining with other elements, as do most metals. and P are always negative in their compounds. Atoms of C, N", and P may have both + an d bonds con- currently. The polarity of the atoms in an elemental molecule must be the converse of each other: that is, + an( ^ (divided polarity). When such a molecule enters into a chemic change, both atoms become of like polarity: that is, -j- or . H has a reducing-power of 2 units, because in combining with other elements its negative atom rises in polarity from 1 to -|- 1: an algebraic difference of 2. In combinations of C, H, and the C bonds united to H are negative; those joined with are positive. VALENCE. This is a very important subject, without which chemic nomenclature can never be really understood. Valence (equiv- alence, quantivalence) signifies the combining or replacing power of an element as compared with H taken as the unit. Those elements which combine with or replace H atom for atom are called monads. Such as require 2 atoms of H to satisfy, or saturate, or neutralize the polarity of 1 atom of the given element are termed diads. The triad atom replaces or combines with 3 of H or any other monad; the tetrad, 4 (or 2 diads); the pentad, 5; the hexad, 6; the heptad, 7; the octad, 8. The Latin adjectives corresponding with these Greek substantives are univalent, bivalent, trivalent, quad- rivalent, quinquivalent, sexivalent, septivalent, and octivalent. Artiads are elements with an even valence; perissads, uneven. Monogenic is a term sometimes applied to monads; polygenic, to all other elements. The law of even numbers is that in all saturated molecules the sum of the perissad atoms is always even, and molecules composed of perissad elements contain an even number of atoms. A diad element, or radical, can be intro- duced into a compound without altering the valencies of other elements: e.g., K KandK K. It will be noticed that a good many elements have more than one valence, the series differing by 2, as a rule. The higher valence is shown only when the element is acting the + role in connection with 0, which, on account of ultra- negativity, seems to draw out the full polarity of the more positive element with which it is combined. The following table shows at a glance the usual valence of each of the more common elements: 76 CHEMIC PHILOSOPHY. MONADS. DlADS. TBIADS. TETRADS. PENTADS. HEXADS. HEPTADS. OCTADS. F Cl S Cl S N Os Cl s N c N Cr Cl Ru Br Hg (ic) P Si P Mn I Cu (ic) As Pt As H Pb B Su (ic) Ag Cd Sb Li Co Au Na Ni Bi K Fe (ous) Cr (mis) Mn (ous) Zn Mg Ca Sr TD^. r>a Sn (ous) The valence of an element can be indicated in one of three ways: 1. By Eoman numerals placed above the symbol and to the right; as, H 1 , O n , N m , C IV . 2. By single dashes representing double (positive and negative) bonds of union, or points of attraction, or poles of the atomic magnet; as, H , , N^^, = C =. 3. By accent-marks written to the right and above the symbol; as, Cl'. Exercise. Practice on combining the positive with the negative elements of the table above, according to their valence, writing the positive element's symbol first. For example: NaCl, PbI 2 , AuCl 3 , SO 2 , PA. The true combining value, or polarity value, of any atom in combination is the algebraic sum of its + and - - bonds. An atom having 3 negative bonds, and another having 3 posi- tive bonds, are of equal valence, but the difference in their respective polarity-value is 6. Thus, KMn0 4 has an oxidizing- power of 5 units, since the difference in polarity between Mn in this compound and Mn in the reduced (deoxidized) man- ganese compound is 7 2, or 5. The lowest possible polarity- value is 4; the highest polarity-value, -j- 8; but the differ- ence between the highest and the lowest polarity-value in the same atom never exceeds 8 units. The algebraic sum of the -j- and bonds holding any two or more atoms together is zero. Any increase or diminution in the polarity-value of any atom or group is always accompanied by an equal converse diminution or increase in the combining atom or group. In- MOLECULES. 77 crease of polarity-value is termed oxidation; decrease of polar- ity-value, reduction. Oxidizing agents are atoms or groups that will sustain a diminution of polarity-value; reducing agents are atoms or groups that can gain in polarity-value. Free, or nascent, is an oxidizing agent, because when it enters into combination with other elements it acquires 2 negative bonds. Free, atomic H is a reducing agent for the converse reason. MOLECULES AND FORMULAS. The molecule has already been defined as the smallest portion of matter that can exist in a free state, or independ- ently. Homogeneous masses are made up of like molecules. When the atoms composing a molecule are alike, the molecule is simple, or elemental; when the atoms are unlike, they form a compound molecule. A radical is an atom or a group of atoms common to a number of compounds. A single atom constitutes a simple radical; a group of unsaturated atoms, a compound radical. For example, the Na atom is a simple radical, characteristic of all sodium compounds; HO is a compound radical present in every hydrate. Compound radicals may be regarded as residues left on removing one or more atoms from a saturated mole- cule; thus, HO, hydrate, is derived from H 2 by dropping one atom of H. The valence of most compound radicals is easily determined by subtracting the sum of positive polarities from the sum of the negative polarities, or vice versa. Fe, Mn, Or, and Al in ic compounds, and Cu and Hg in ous compounds, unite, each element with itself by one bond of union, forming pairs with reduced total valence. A formula is a combination of symbols representing a molecule, as NaCl. which stands for a molecule of sodium chlorid, made up of an atom each of Na and Cl. H 2 is the formula of hydrogen oxid, or water, which is composed of 2 parts of H and 1 of 0. In writing formulas we place the -|- element, or radical, always first, the element, or radical, fol- lowing, taking care that the valence of each is satisfied. The multiplication of atoms is shown by small figures written to the right and below the symbol, as in H 2 or HgCl 2 . Compound radicals taken a number of times are inclosed in parentheses; thus: (NH 4 ) 2 S0 4 . The following table of compound radicals and their va- lences should be learned by heart: 78 CHEMIC PHILOSOPHY. PPPPPPPP22QQQQ ppbpp pP || || || || II (i || $ II I- || |j n . MM." " (f _ Ji, tr 1 II 1 1. 8 ^1^1 2-^^pS o' ? "l*ff fl }il E^ ^ IS g: r f o d o ^3 B II 11 f II II 1 & II s Q ._ M CO H * li i i si w " g ^ N g w !l i s i ; 3 i * M 1 " 8 CO M a 3 p 3 W II || 6? i) || II fe 5 O o ^ H S II g || fc II **" CO -* O I-* ^, >o Oi l-i ^ 3 Oi CO M O N H 3 li ff II f 11 SB II O i to H s: ii s ii & ii *o of 1 a 3 S 9 ^ W ?i M' ro ? t> || M ^ ii M 01 if II ui >- I- 1 CO || l-i 1 * w o^ " d 3 $ % Q II II li # f SMI II o g S i;.i.lM Oi " ^ g ii o S3 ii n li iT -l H 2J M i i CO o 3 p ? g 1 ;? || (9 II ^ "TJ 2 M HH QUESTIONS. 87 stated with formulas. Thus, let it be required to find how much zinc oxid can be obtained from 100 gm. of zinc: Zn : ZnO : : 100 : x 65 : 81 : : 100 :x Answer is 124 8 / 13 gm. Such calculations are of immense importance in manu- facturing chemistry. The branch of the science that they con- stitute is known as stoechiometry. The unit of weight for gases is the crith (0.0896 gm.), the weight of a liter of H in a vacuum at and 760 mm. pressure. THE PERIODIC LAW. The most satisfactory classification of the elements is that of Mendelejeff, which is based upon the atomic weights. He observed that the first seven elements after H were repre- sentative of as many groups of similar elements. Each of these is put at the head of a vertic column, inclosing the elements which it resembles. The lateral rows, or series, or small peri- ods, two of which make a large period, run in the orders of the atomic weights, with a few breaks here and there. It will be noted that alternate numbers of the same group resemble each other more than do adjacent numbers. With the aid of this table its author predicted the properties of Ga, Ge, and Sc while these elements were still undiscovered. Doubtless the other vacant places will be filled in time. Group VIII is made to include a number of intermediate elements which may later be arranged in a set of groups. QUESTIONS ON THEORETIC CHEMISTRY. 1. Name and give symbols of ten elements whose names begin with C. 2. Name five elements which have both an English and a Latin name. 3. Name a liquid element. 4. Peroxid of hydrogen gives off atomic O. Is this more or less active than the atmospheric O? 5. Why does NaCl dialyze more readily than Gaell^O.? 6. What is the density of As in the gaseous state? 7. Why is density always one-half the molecular weight? 8. Calculate from the table the molecular weight of H 2 S0 4 , avoid- ing fractions and using the nearest whole numbers. 9. What is the most important distinction between metals and metalloids ? 88 CHEMIC PHILOSOPHY. 10. Which is likely to be more stable: a compound of O and N or one of and As? 11. What element is the unit of valence, atomic and molecular weight, and density? 12. Why does enter into more chemic combinations than any other element? 13. Name a monad, a diad, a triad, a tetrad, a pentad, a hexad, a heptad, and an octad. 14. What element has the highest atomic weight, and how much is it? 15. Why should we expect P rather than Hg to show allotropic tendencies? 16. Why do elements combine in simple proportions? 17. Give reasons for the law of even numbers. 18. Write formulas of potassium iodid, calcium oxid, mercuric chlorid, carbon dioxid, and sulphur trioxid. 19. What is the valence of the radical Si0 4 , and why? 20. Write formula of ferric ferrocyanid ; of ferrous *f erricyanid. 21. Write graphic formulas of some acid, base, and salt. 22. Name: (Fe 2 ),(P 2 O 7 ) 3 ; (BiO)N0 3 ; Na 2 B 4 O 7 ; HC 7 H 5 O 3 . 23. Write graphic formulas of ferric chlorid, mercurous iodid, and manganic sulphate. 24. Translate "protiodid of mercury, sesquichlorid of iron, and ter- sulphate of iron" into modern chemic nomenclature. 25. Name and give basic formula of a monobasic, dibasic, tribasic, tetrabasic, and hexabasic acid. 26. Name a diacid base. 27. What two elements are present both in bases and in oxyacids, and in what way as regards composition do these two classes differ? 28. What substance is always formed when an acid and a base are brought together? 29. Mention and give formulas of five salts, each formed in a dif- ferent way. 30. Name an acid salt which is alkaline in reaction. 31. Write equation for reaction between CaS0 4 and Na 2 C0 3 . 32. Find percentage by weight of O in H 2 0. 33. Find percentage by weight of Ca in CaCO 3 . 34. What percentage by weight of CO 2 gas is given off on burning limestone (CaCO 3 )? 35. How much AgN0 3 can be made from 108 grams of silver? 36. How much NaCl is required to make 500 gm. of HC1? (2NaCl + H 2 S0 4 = 2HC1 + Na 2 S0 4 .) 37. What is the volume of a kg. of H at standard temperature and pressure ? 38. Calculate the percentage composition of potassium nitrate. 39. What is the weight of a liter of O? 40. What weight of NaHO is required to neutralize a mg. of HC1? INORGANIC CHEMISTRY. METALS. THESE are solid substances (except mercury and hydro- gen), electropositive, and good conductors of heat and elec- tricity. Their oxids form bases with H 2 0. DISCOVERY AND DERIVATION. Au, Ag, Hg, Sn, Cu, Zn, Pb, and Fe were known to the ancients. The corresponding Latin names from which the symbols were derived are aurum (color of fire), argentum (white), hydrargyrum (liquid silver), stannum (stone), cuprum (island of Cyprus), zincum (German, zinn or tin), plumbum (heavy), and ferrum. Antimony (from anti and moine, because some monks were poisoned with it; stibi is the Greek name for native sulphid) and bismuth (German wismuth, meaning variegated tints) were discovered in the latter part of the fifteenth century. Arsenic (male or strong) was discovered by Schroder in 1694; cobalt (mine-demon) by Brandt in 1733; platinum (little silver) by Wood in 1741; nickel (worthless) by Cronstadt in 1751; manganese (confounded with Mg) by Galm in 1774; molybdenum (Greek for lead) by Hjelm in 1782; and chromium (color) by Vanquelin in 1797. Humphry Davy in 1807 and 1808 first separated K, Na, Ca, Ba, Sr, and Mg from their oxids. The first element is so called from pot- ash, and its symbol is derived from kali, the Arabic word for ashes. Sodium refers to soda-ash; natrium to natron, the old name for natural deposits of Na 2 C0 3 . Calx is the Latin name for lime, or CaO. Barium is of Greek origin, and means heavy. Strontium is named after the Scottish village Strontian, where SrC0 3 was first found. Magnesium derives its name from Mag- nesia in Asia Minor. Cadmium (from calamine) was isolated by Stromeyer in 1817; lithium (stone) by Arfvedsen in 1817; and aluminum (from alum) by Wohler in 1828. Many metals have been named after persons, places, and deities: for example, cerium after the goddess Ceres; colum- bium or niobium after Columbia and Niobe; gadolinium after John Gadolin; gallium from Gaul; germanium from Germany; masrium from the Arabic name of Egypt; palladium after (89) 90 INORGANIC CHEMISTRY. Pallas; ruthenium from the Latin name of Kussia; scandium after Scandinavia; tantalum after Tantalus; terbium, ytter- bium, and yttrium after Ytterby in Sweden; thorium after Thor; thulium after Thule; titanium after the Titans; ura- nium after the planet Uranus; and vanadium after the Van goddess Vanadis. Some are named after the color-lines seen in the spectroscope, as cesium, bright blue; indium,, indigo; rubidium, red; thallium, green. Others take their names from some physic properties of the metal or its salts: e.g., glucinum, sweet; iridium, rainbow; rhodium, rosy; lanthanum, unseen; osmium, odor; samarium, samarskite; tellurium, earth; tung- sten, from the Swedish, meaning weighty stone; wolf ram, mean- ing wolf-cream; and zirconium, jargon. Ammonium was so called after Jupiter Ammon, near whose temple in Libya the Arabs of the desert long ago made NH 4 C1 by distilling camels' dung as a substitute for common salt. Praseodymium (garlic) and neodymium (new) are derived from didyniium (double) which was formerly believed to be an element, but is really a mixture of the two metals first mentioned. ORDINARY SOURCES OF METALS IN NATURE. Gold: river-beds and rock-veins; always free except as tellurid. Platinum and Pd, Rh, Ir, Ru, and Os: river-beds. Bismuth: also as oxid and sulphid. Free State \ Silver: also as sulphid, chlorid, and tellurid. Mercury: minute, disseminated globules. Copper: cubes and octahedra; usually oxids, sulphates, and carbonates ; also found in hulls of various grains. [ Arsenic: rarely free in lamellar, kidney-shaped masses. Chlorids are commonly known as horn; sulphids as glance. COMBINATION. Light Metals. Sp. gr. below 4. The Alkali Metals. On account of the ready solubility of their salts, they are not found to a great extent as ores, and never occur in a free state. K is obtained as carbonate from the ashes of land-plants (sugar-cane, beet-root, marc, etc.); also from the double chlorid of K and Mg (carnallite), which is extensively mined at Stassfurt, Germany. K compounds, especially the carbonate, constitute, by weight, about one-third of sheep's wool, and are essential ingredients of all the formed elements of the human body. Na is very abundant as the chlorid arid the sulphate in all soils and natural waters and in atmospheric dust. The silicate of Na is present in the tissues of plants; the chlorid, phosphate, and carbonate are very nee- EXTRACTION OF METALS. 91 essary ingredients of the blood and its secretions. Li salts arc comparatively rare. They are found in mineral springs mid are also obtained from the ashes of the beet and tobacco. NH 3 is present in decaying nitrogenous matter generally: e.g., in barn-yard manure. The chief commercial sources of NH 4 compounds are the guano-beds of South America and the am- moniacal liquors obtained as a by-product from coke-, iron-, and gas- works. Cs and Kb are both very rare metals and of no present practical importance. Alkaline Earths and Mg. These occur chiefly as sulphates, carbonates, and silicates. Next to Al, Ca is the most abundant terrestrial metal, being present in all soils and natural waters, and hence in the tissues and juices of plants and animals. Sr is found in small amounts in sea-water and sea-plants (Fucus vesiculosus) and in certain mineral springs, as well as in ores. Ba is found only in combination, and may be obtained in small quantities from the ashes of sea-plants and of some trees, par- ticularly the beech. The metal Mg is never found free. In combination it is widely distributed, usually with Ca. Mg salts are present in plants in considerable quantities. Aluminum. This metal, though never found free, is the most widely distributed in the earth's crust, making, as it does, in the form of silicates, oxids, hydrates, and fluorids, the great mass of common rocks, which in their natural decom- position turn into clay. Heavy Metals. Sp. gr. above 4. SulpJiids Chiefly. As, Sb, Co, Ni, Cd, Mo, Hg, Pb, and Cu. Oxids Chiefly. Sn, Mn, and Cr. Sulphid and Chlorid. Ag. Sulphids, Oxids, and Carbonates. Fe and Zn. Meteoric Rocks. Fe and Ni. Common Associations. Co and Ni; Fe and Mn; Cd and Zn; Ag and Pb; Ca and Mg. Co and Ni are obtained almost entirely from mines in Ontario and New Caledonia. The color of ordinary rocks is due to iron; also the color of blood and green plants. Uranium and the radio-active metal radium are obtained from pitchblende. EXTRACTION OF METALS. Electrolysis. From fused chlorids usually; Al (from bauxite); alkali metals and alkaline earths; Mg. Pure Cu, crystal Au, and other metals are obtained by electrolysis by suspending plates of the same metals in solutions of their salts. 92 INORGANIC CHEMISTRY. Decomposition with metallic Na or K; weaker metals driven from their combinations; Mg, Al, Ca, B, Sr, U. Roasting, usually with sulphids or oxids, and reduction with charcoal, lime, or iron slag. Lead. PbS + 2PbO = 3Pb + S0 2 . PbS + PbS0 4 = 2Pb + 2S0 2 . Another method is to roast the ore to form oxid, then combine with silica, and reduce this silicate in a blast furnace with reduced iron-ore. Mercury. HgS + 2 = Hg + S0 2 . Iron is sometimes added. Collect under H 2 0, strain through linen or chamois, and distill. Copper. 2Cu 2 + Cu 2 S = 3Cu 2 + S0 2 . Ore is fused with a siliceous flux, sometimes containing CaF 2 . The resulting "blister copper" contains some Cu 2 0, which is removed by fusing with coal and stirring, or by electrolysis. Zinc. Charcoal reduction. Antimony. Charcoal reduction. Arsenic. Charcoal reduction. Manganese. From carbonate or oxid. Chromium. From oxids with charcoal. Tin. From oxids. Nickel. Eesulting "speiss" is dissolved in HC1, pptd. with H 2 C 2 4 , and reduced with lime and carbon. Cobalt. Same as for Ni. Bismuth. Fused (after roasting) with slag, iron, and char- coal. Melted mass settles in two layers; the lower contains Bi. Alkali Metals. Old method = charcoal reduction of car- bonate, distilling metal and passing through naphtha. Fractional Distillation. Cadmium. Separated from zinc. Zinc. Oxid or carbonate reduced with charcoal in iron retorts, and liberated metal distilled over. Mercury. When cinnabar is heated with lime the metal Hg volatilizes. It can be refined by redistillation, and on a small scale by pouring the dirty metal through a filter-paper having a small pin-prick at the bottom. Sublimation. Arsenic from mispickel or white arsenic. Reduction of heated ore with H: Much employed in laboratory, but not on a large scale. Eeduced iron is obtained this way. Fe 2 3 + 3H 2 = 3H 2 + Fe 2 Special Methods. Silver. The mode of separating Ag from its ores varies with the particular combination. There are five main processes employed. 1. The electrolytic method EXTRACTION OF METALS. 93 is applied to ores alloyed with Cu or CuO. 2. In the amal- gamation process, as practiced in the United States (Washoe process), the silver ore is ground with Hg, common salt, and CuS0 4 (and sometimes 2 per cent. Na to prevent "flouring or sickening" of the Hg). After straining the Ag amalgam, the quicksilver is separated by distillation, leaving a residue of Ag. 3. Wet extraction is accomplished by roasting ores containing AgS, Cu, and Fe at such a temperature as to form the oxids of Cu and Fe and the sulphate of Ag. The latter salt is sepa- rated from the insoluble oxids by lixiviation with H 2 0, and is then pptd. with metallic Cu. Or common salt is added to the ore before roasting, forming AgCl, which is dissolved out from the other matters with Na 2 S 2 3 , pptd. with Na 2 S as a sulphid, and finally reduced by intense heat and a current of air. 4. The cupellation process is probably the most ancient. It is applied to argentiferous lead ores, which are roasted in a reverberatory or blast furnace. The lead is largely oxidized and skimmed off. When Pb is in great excess, as is generally the case, it must first be partly removed by melting (Pb fuses at 328, Ag at 1040) and fractional crystallization on cooling (Pattinson's process); or by alloying the melted ore with 18 parts Zn to 1 of Ag, then oxidizing the Zn and washing the oxid away with H 2 0. 5. The rather recent cyanid process de- pends on the solubility of Ag in the alkaline cyanids. Ag, obtained by any of these methods, is rendered chemically pure by dissolving in HN0 3 , ppt. with HC1, and reducing the result- ing chlorid with Na 2 C0 3 . Iron. This metal is extracted from oxids and carbonates by reducing with alternate layers of coal and limestone in a double, conic, fire-clay blast furnace. The limestone combines with the silica of the ore to form a fusible glass (cinder or slag). C0 2 is produced at the bottom of the furnace, while the CO formed in the body of the furnace acts as a reducing agent. The resulting molten Fe takes up some C as it sinks to the bottom, where it is run off into molds as cast- or pig- iron. It contains 3 to 6 per cent. C, a little Si, and traces of S, P, and Mn. Wrought Fe is nearly the pure metal, containing less than V 2 of 1 per cent. C. It is made from cast Fe by a process of thorough oxidation termed puddling, conducted in a blast furnace with constant stirring. Steel contains from 0.8 to 1.5 per cent. C. It is made nowadays chiefly by the Bessemer process, consisting essentially of the addition to molten wrought Fe of a certain proportion of spiegeleisen, or ferromanganese, which is a mixture of white cast Fe with about 7 per cent. Mn. The open-hearth process is similar, except that it is per- 94 INORGANIC CHEMISTRY. formed on the hearths of reverberatory furnaces. The requisite amount of C is obtained by adding ferromanganese or by filter- ing over carbon filters. Cement or crucible steel is made by carbonizing in furnaces wrought Fe packed in charcoal and siliceous material. The resulting "blister steel" is melted in crucibles and cast in small ingots. Gold. There are four main processes of extraction: 1. Placer mining (panning, cradling, hydraulic mining), in which the Au is separated from sand and earth by washing through Fig. 20. Sectional View of Blast Furnace. troughs which contain Hg in hollows or on Cu plates to catch the gold in its downward passage. The Au and Hg are parted by distilling in a retort. 2. Stamping quartz to a fine powder and then washing away the lighter earthy matter. 3. The Cl process for pyritic ores, which comprises the following steps: Roasting, mixing with H 2 0, and saturating with Cl for twelve hours to form AuCL, which is pptd. from solution by adding FeS0 4 or oxalic acid, as a fine brown powder (spongy or crystal- line gold). PHYSIC PROPERTIES OF METALS. 95 6FeS0 4 + 2AuCl 3 = 2Fe 2 (S0 4 ) 3 + Fe 2 Cl 6 + 2Au 3H 2 C,0 4 + 2AuCl 3 = 6C0 2 + 6HC1 + 2Au The ppt. is washed, placed in a crucible lined with borax, melted, and poured into an ingot. 4. The cyanid process de- pends on the solubility of the metal Au in solutions of the alkaline cyanids. Au is separated from Ag by electrolysis or by dissolving out the latter with HN0 3 or H 2 S0 4 . If neces- sary, before "parting," enough Ag must be added to make about 3 to 1 of Au: a procedure known as quartation. Cu is separated with H 2 S0 4 . Gold is purified by dissolving in nitro- hydrochloric acid and precipitating with FeCl 2 . 2AuCl 3 + 6FeCl 2 = Au 2 + 3Fe 2 Cl 6 The corrugated non-cohesive Au used by dentists is said to be prepared by tightly packing sheets of Au between leaves of unsized paper in Fe boxes, and then heating sufficiently high to carbonize the paper. Platinum. Deville's method of extraction consists in melting the ore with an equal weight of PbS and half as much Pb, which take away the Pt from the other metals. This alloy is then fused with access of air; the Pb is oxidized and flows off as a slag, leaving Pt as a spongy mass. This is now melted in a lime-furnace by means of the oxyhydrogeu-blast lamp, and poured into molds. Pt black is prepared by dissolving the metal in aqua regia, evaporating excess of acid, then boiling with a strong solution of KHO and adding grape-sugar. Ammonium. Free NH 4 can be prepared by heating Na in a sealed tube with NH 3 and then heating this product with XH 4 C1 in another sealed tube. NaCl is formed, and also a dark-blue lustrous liquid, which soon decomposes into H and NH,. Granulated Metals. Zinc and other granulated metals are prepared simply by melting and pouring into H 2 0. Zn becomes brittle when melted several times, owing to formation of ZnO and contamination with the Fe of the ladle. It can be purified by throwing on the molten metal some dry NH 4 C1. PHYSIC PROPERTIES OF METALS. All are solid at ordinary temperatures, except NH 4 and Hg, which solidifies at 39.4 and boils at 357 W*- H is sometimes considered a gaseous metal. Metals are electro- positive and opaque, except in very thin sheets. Nearly all 96 INORGANIC CHEMISTRY. f% "i 3 n ^ BBs*5.B&9*f* 3 g & 7; 5- g^ - s PH. S? = ..! 3 -3 2 5 ? sr 5 rn 5* " RELATIVE HARDNESS.I FUSING- POINT (C.). LINEAR EXPANSION.2 HEAT CONDUCTION .3 S - ELECTRIC CONDUCTION.* b bb SPECIFIC HEAT. PHYSIC PROPERTIES OF METALS. 97 are sectile: i.e., can be cut without crumbling. Metals occur- ring free in Nature are generally crystalline, and all probably can be made to crystallize, cubes and octahedra being the prevailing types. When unoxidized, they present a shining appearance, called metallic luster, and are capable of being polished. Nearly all metals are more or less white in color, often with a gray or blue tinge. Finely powdered metals often lack metallic luster. The alkaline earthy metals are yellowish. Gold is yellow (brown in powder); Cu red; powdered As, Sb, Ag, Pt, and Fe black. Bi and Co are white with a pink tinge. Thin leaves of Au appear green or purple by transmitted light, and molten Au is bluish green in color. Cast-iron is white or gray, according as the union of Fe with graphite is chemic or physic. Heated Cu and freshly-tempered steel exhibit a rain- bow of colors. As and Sb are characterized by a garlicky odor, brought out on heating. Fe, Cu, and Zn also yield an odor on heating. Cu has the most decided metallic taste. In sp. gr. metals vary from Li (0.59) to Os (22.47). The common alkali metals are lighter than H 2 0; Mg and Ca about 1 3 /4 times as heavy; Al and Sr, 2 1 / 2 times; and Ba, 3 3 / 4 . These are termed the light metals. The remainder have a sp. gr. above 6 (see table) and are called heavy metals. The sp. gr. of Fe is less the more C it contains: wrought iron, 7.8; steel, 7.6 to 8; cast-iron, 7.1. Cast metals are a little lighter than the same in wire or wrought. Experiment. Float a piece of Fe on Hg. In hardness metals vary greatly. The alkali metals are waxy and are easily cut with a knife. Of common every-day metals Pb is softest, and hence is often taken as the unit of hardness (see table). It cuts readily, and when rubbed on a piece of white paper leaves a gray streak. Sn can also be scratched with the finger-nail. Fe and Cu are 2.4 times as hard as Pb, and Ni 2.5 times as hard, being the hardest common metal. Ir is the hardest metal and scratches the best steel. Au and Ag are too soft alone for commercial use; hence they are alloyed, the former with Ag (pale or green gold) or Cu (red gold), the latter with Cu. Au is also toughened by fusing with a flux of 1 part each charcoal and ISTH 4 C1 added to the gold just before melting. Aside from Hg, the lowest f.p. is that of Ga (30), and next to this come Eb (38.5), K (62.5), and Na (95.6). Also fusible below a red heat are Li, Sn, Bi, Cd, Pb, Zn, Mg, Sb, and Al. Metals of the alkali earths melt at a red heat. Ag, 98 INORGANIC CHEMISTRY. Cu, and Au require a bright-red or white heat to melt them. The f.p. of Fe varies inversely with the percentage of C it con- tains. That of cast Fe is about 1200; steel, 1400; wrought Fe, 1600; Ni, Co, and Pd likewise require a high forge-heat to melt them, while Or, U, Mo, and W do not melt in the forge, but agglomerate. Pt, Ce, Ir, and Os are infusible in the ordi- nary blast furnace, but are melted by the oxyhydrogen blow- pipe. Fe and Pt become semiliquid or pasty on heating suffi- ciently, and hence can be welded. Alloying with other metals lowers the m.p. Mg, Zn, and metals of the alkalies and alkaline earths burn easily. As and Hg are quite volatile, and Cd, Zn, and Pb volatilize at a red heat or higher. Sb and Bi have the peculiar property of expanding on cooling. As shown by the table, each metal expands at a definite rate on heating a given number of degrees. Metals as a class are good conductors. Ag ranks first in conducting-power, both for heat and electricity, with Cu a close second. Bi stands at the bottom in these respects. The specific heat of common metals ranges from Bi (0.0308) to Na (0.2934). Al requires about twice as long to reach the same temperature as Fe. In tenacity the more fibrous metals (Co, Ni, Fe, Cu) lead. Pb ranks very low in this property. As, Sb, Bi, Mn, and Zn are noted for their brittle character. The last named is made malleable by heating to 120-150; it becomes brittle again at 205. Wrought Fe is the softest and toughest of the three forms of Fe. It is quite malleable when heated. When heated steel is cooled rapidly it becomes hard and brittle; if cooled slowly it retains its elasticity as well as hardness, and may be forged and welded. It is tempered by heating to 220 or 320 and cooling slowly. Fe and Au increase in tenacity at 100; less so above this. Au is first and Ag second in malleability and ductility. These properties of Au are much impaired by even minute traces of Pb, Bi, or Sb. Great cold renders all metals more brittle. Annealing, or heating and cooling, re- stores the normal malleability and ductility lost by working. Metals are generally deficient in elasticity, except steel. The addition of a small proportion of Pt to Au greatly increases the elasticity of the latter. The more elastic metals are generally sonorous. Sn and Cd crackle ("cry") when bent, owing prob- ably to the friction of their crystals. Metals and their alloys tend to become crystalline on percussion and other mechanic forces. Fe is paramagnetic; Mn, Ni, Cr, and Co slightly so. Bi is the most diamagnetic metal. Al and Mg are permeable to the x-rays. Many metals in the molten state absorb or occlude CHEMIC PROPERTIES OF METALS. 99 0, giving it off again on cooling, sometimes with "spitting" of the metal. Metals, like the metalloids, sometimes assume different ap- pearances and other properties or allotropic forms. As, for example, has a steel-gray crystalline and two amorphous (friable black and gray) forms. Ag may assume a white, black, blue, bluish-green, red, purple, or yellow color. CHEMIC PROPERTIES OF METALS. The lighter metals are, generally speaking, more active chemically than the heavy metals. Solubility. HN0 3 dissolves all metals except Al, Au, Pt, Sb (forms antimonic acid), and Sn (forms white metastannic acid). Pb, Ag, and Fe are soluble in dilute, but not in strong, HNO a . When Fe is immersed in the strong acid, it is rendered passive: i.e., incapable of being dissolved in the weaker acid unless heated or unless some other metal as Cu, Ag, or Pt is also present. If Pt is alloyed with Ag, HN0 3 dissolves it. A gold-silver or gold-copper alloy containing less than 25 per cent. Au is disintegrated by HN0 3 , which dissolves the other metal, leaving Au. If there is more than 25 per cent. Au, enough Ag or Cu must be fused with the alloy (quartation) before the acid will remove all the Cu or Ag. HC1 dissolves all metals except Sb, Hg, Ag, Pb, Au, Pt, and Bi. Dilute H 2 S0 4 dissolves all except Sb, Al (soluble on boil- ing), Pb (slightly), Au, Pt, Cu, and Hg (soluble in concen- trated). Strong II 2 S0 4 forms a coating of sulphate, which, not being dissolved away, soon stops chemic action. Aqua regia dissolves Au (quickly), Pt (slowly), and Sb (also soluble in hot HC1 and in hot H 2 S0 4 ). Insoluble in acids are Cr, Rh, Ir, and Ru. The metals replace and set free H in acids, forming salts. Caustic alkalies dissolve the weaker metals, Zn, Al, and Sn, forming zincates, aluminates, and metastannates. NaCl and organic acids dissolve Zn (often contains As). KCN dissolves Au, Ag, and Cu. Al is dissolved by certain vegetable acids, especially in the presence of N"aCl. Ammonia- water dissolves Cu slowly, the process being hastened by allow- ing access of air. Cu is also attacked by vegetable acids in the presence of air and moisture; hence culinary preparations containing vinegar or lemon-juice should not be placed in Cu vessels. 100 INORGANIC CHEMISTRY. Action of Air. Noble metals (An, Ag, Pt, Hg, Pd, Rh, Eu, Os, and Ir) do not oxidize on exposure to air; the rest are termed base. Cu, Zn, Al, and Sn do not oxidize in dry air. In moist air Zn and Mg become covered with a film of oxid (pre- vents further change); Cu with a green deposit of basic car- bonate; Pb with a blue-gray coating of carbonate and sulphid. Iron-rust, that forms in moist air or H 2 0, is a mixture of Fe 2 (HO) 6 and Fe 2 3 . Tarnishing of silverware is due to the formation of Ag 2 S by the H 2 S in the air of houses; Cd turns yellow from the same cause. Alkali metals oxidize very quickly, and must be kept in oily liquids (benzene) that contain no 0. Action on Water. Metals of the alkalies and alkaline earths decompose H 2 0, sometimes with a colored flame of H, and form hydroxids: K + H 2 = KHO + H Red-hot Fe dipped into H 2 decomposes the steam that is formed, setting H free and producing the "blacksmiths' scales" of Fe 3 4 . Powdered Mn also decomposes H 2 0. Pb is slightly soluble in H 2 0, and this solvent action is increased by the presence of chlorids, nitrates, and nitrites, and decreased by carbonates and sulphates, which form an insoluble coating on the inner surface of the pipes. Generally speaking, the softer the water, the greater the danger of Pb being dissolved by it. Sn, Zn, Fe, and Mg ppt. Pb from its solutions. Experiment. Make a "lead tree" by dipping a strip of Zn into a solution of lead acetate. Normal salts of Bi decompose on the addition of much H 2 0, with ppt. of oxysalts or subsalts. Oxids of metals com- bine with H 2 to form hydroxids (rarely acids, when there is a very large proportion of 0), and both oxids and hydroxids combine with acids to form salts. Direct Combination. All metals unite directly with Cl, F, and 0; most with Br, I, and S; many with C and P and As. Freshly prepared ferrum reductum burns readily with a red glow. A strip of Zn, Sn, or Fe ppts. Pb or Bi from solutions of their salts; a stick of P or other non-metal collects crystal- line Au from a heated solution of one of its salts; Zn, FeS0 4 , H 2 C 2 4 , and H 2 S0 3 also ppt. Au. Hg dissolves all other metals directly or indirectly (Na amalgam) except Fe, forming weak chemic compounds known as amalgams. Experiment. Drop a globule of Hg into a solution of AgNO 3 , and note formation of "arbor Dianae." Experiment. Make NH 4 amalgam by adding bits of Na to some Hg in a test-tube, and pouring on the solution a strong solution of CHEMIC PROPERTIES OF METALS. 101 NH 4 C1. NaCl and an amalgam result. The latter soon swells up and decomposes, with the evolution of NH 3 and H, only Hg remaining. Pt sponge may be amalgamated by triturating in a warm mortar with Hg and acetic acid. Experiment. Clean a copper cent with HN0 3 , and spread on a globule of Hg to "silver" it. Why does it turn green later? Molten cast-iron dissolves C, forming a carbid. The chief impurities of cast-iron are S, which renders it brittle when hot ("red-short"), and P, which renders it brittle when cold. Sb and As unite readily with most metalloids and with many metals, thus playing both the + and the role. Both form poisonous combustible gases (H 3 Sb and H s As) with H. Cu on heating becomes coated with black CuO. Mg burns readily with an intense-white light rich in actinic rays. Zn is also combustible at a bright-red heat. Cd burns under the blow- pipe, leaving the brown oxid. As and Sb burn with a bluish- white light and garlicky odor; Te with a blue flame tinged with green; In with a violet flame. The alkaline and alkaline earthy metals also yield characteristic flames (see "Pyrology"). Ozone and H 2 2 corrode most metals by breaking up and giving off nascent 0. Series of Salts. Apt to change spontaneously, one into the other. Ferrous and Ferric. In these two series the metal is a diad and a triad, respectively. In ferric compounds there are always 2 atoms (or some multiple of 2) of Fe to each molecule. Theoretically the valence of Fe is 4 in ferric compounds, but the two atoms combine with each other so as to lose one bond of union for other elements, as shown by the graphic formula of Fe 2 Cl 6 : Fe= Cl Cl Cl Fe= Cl Cl Cl Ferrous compounds are usually greenish in color; ferric salts, reddish. They undergo spontaneous change, one class into the otUer, on exposure to the air, as well as by artificial reduction or oxidation. Experiment. Convert FeSO 4 into Fe 2 (SO 4 ) 3 by heating a solution of the former with dilute HN0 3 , and note corresponding change in color. 102 INORGANIC CHEMISTRY. Ferrous salts can be made by dissolving Fe in the corre- sponding acid: ferric salts, by dissolving Fe 2 3 in the acid of the salt desired. Mercurous and Mercuric. In mercurous compounds Hg acts as a monad; in mercuric, as a diad. The ous salts are probably unsaturated as to valence, and are prone to decom- pose into metallic Hg and the corresponding ic compound. The relation of these two series is readily seen by comparing the graphic formulas of Hg 2 Cl 2 and HgCl 2 : Hg Cl Cuprous and Cupric. The ous and ic salts of Cu corre- spond in structure to those of Hg. Cuprous compounds are even more unstable than mercurous ones. Cobalt Salts. Hydrated Co salts give pink solutions; an- hydrous ones blue. Experiment. Make sympathetic ink by dissolving some Co(N0 3 ) 2 in water. Write with this 'solution and a glass rod on white paper and let dry. The writing is invisible. Now dehydrate by holding the paper near the flame, and the characters will appear plainly in blue. Ammonium Compounds. These on exposure to the air give off the gas NH 3 ; hence the term volatile alkali applied to this metal. Experiment. With moistened red litmus-paper, held above the open neck of the bottle, show volatility of NH 4 HO, and notice that the red color is restored on drying. Zinc salts are all white, as are nearly all the salts of the alkaline and alkaline earthy metals. Magnesium salts are soluble in the presence of ammonium compounds, with which they form double salts. Protein-silver compounds, such as protargol, are readily soluble in water, the solution having marked antiseptic prop- erties. Scale Compounds. These are chiefly ferric salts with or- ganic acids. They are prepared by evaporating to a syrupy consistence, pouring on plates, and peeling off when dry. Official are ferric citrate, ferri et ammon. cit., ferri pyrophos., ferri et quin. cit., ferri et strych. cit., ferri et ammon. tart., and ferri et potassii tart. Actinism. Ag salts are very susceptible to the action of light, being reduced to the black, finely divided metallic state, especially in the presence of organic matter. PHYSIOLOGIC PROPERTIES OF METALS. 103 Experiment. Show silvering of glass with solution of Rochelle salt, strong' AgNO 3 solution, and enough NH 4 HO to nearly dissolve precipitate, warming carefully. Chemic Corrosion. Au is corroded by fused alkalies and fused saltpeter, and slightly by selenic acid. Pt is corroded by P, fused alkalies, sulphids, hydroxids, nitrates, and cyanids, silica, and by easily reduced oxids, particularly those of Pb. PHYSIOLOGIC PROPERTIES OF METALS. None of the metals have any distinct action on or in the body until converted into compounds by the digestive juices or otherwise. Hg is most employed, either rubbed with chalk (gray powder), or with lard and suet (mercurial ointment), or with licorice-powder and rose honey ("blue pill"). The thera- peutic alterative activity of these preparations is due to Hg 2 formed by oxidation of the finely divided ("dead or extin- guished") metal. Hence the better rubbed and the older, the stronger they will be. Salts of the less positive metals, Zn, Al, Cu, Fe (vegetable acid salts not constipating), and Pb (also sedative) are gener- ally astringent, especially the sulphates. Bi salts are soft and insoluble; hence used as mucous-membrane sedatives. Mg salts are generally laxative and antacid. Fe is an essential element of blood-corpuscles, and is therefore much used as a hematmic. As is a valuable alterative and nerve-tonic. Liquid As official preparations are of 1-per-cent. strength; dose, 2 to 10 minims. Many metallic salts, particularly of Bi and Fe, when taken internally blacken the stools by uniting with H 2 S in the intestines. The salts of the alkali metals are white and solid and mostly fusible at a red heat. Practically speaking, all are sol- uble in H 2 0, but much less so or not at all in alcohol. The hydroxids and carbonates are peculiar in not being decomposed by heat. Most K salts are deliquescent; most Na salts efflo- rescent. K compounds are the strongest physiologically and the most irritating and depressant. The stimulating properties of NH 4 compounds depend largely, no doubt, on the contained N. The various salts of each metal are usually prepared by treat- ing the most abundant and accessible compound with the acid of the salt desired or with a solution of some reagent contain- ing the desired radical. The salts of the alkali metals are the most common and useful mineral medicines. They are used as cathartics and antacids, and even more as suitable vehicles for the administration of medicinal negative elements: e.g., 104 INORGANIC CHEMISTRY. NaBr for Br, KI for I, etc. The alkaline salts of the vegetable acids are oxidized into carbonates in the system. The common Ca compounds are essential to the life and growth of all living beings. Sr is preferred as a base for I, Br, and salicylic acid, since it is non-irritant to the stomach. Salts of the heavy metals generally are changed into albumin- ates before absorption into the blood; hence are often advan- tageously given in milk. Caustic alkalies act as corrosive poisons; large doses of heavy metals (except Fe) act as irri- tants mostly. Most of the heavy metals may give rise to chronic poisoning due to medication,, occupation, or environ- ments. Hg and As vapors are extremely poisonous. Metals of the same group vary in toxicity directly as their atomic weights. USES OF METALS. The most important of the industrial metals are Fe, Al, Cu, Zn, Sn, and Pb. Fe is the most useful metal, and is em- ployed in innumerable ways. So necessary has it been to the progress of the race that the historic period of the earth is often styled the iron age. Wrought or bar Fe is of special use for building purposes and Bessemer steel; white cast Fe for forging, puddling, and steel; cement steel for armor plates; carbon or crucible steel for springs, tools, and firearms; open- hearth or low-carbon steel for tires, tanks, fire-boxes, etc.; and Bessemer steel for rails and construction material. The metal Al is the best suited of all metals for culinary vessels, on account of its lightness and because it does not tarnish nor is acted on by vegetable acids so much as Zn, Sn, and Cu are; it is, moreover, not at all poisonous. Al is also employed for covering roofs and monuments, for ornamental purposes, and in dental plates, and is sometimes used with S in vulcanizing rubber. Zn is used in the manufacture of brass, desilvering Pb, in dental dies, electric batteries, and for coating or "galvanizing" sheet iron for roofing, pails, tubs, etc. The Fe is cleansed in dilute H 2 S0 4 and then dipped into molten Zn. Cu is utilized for money, electric wires, cartridges, various utensils, in sheathing ships, and to give a ruby color to glass. Its alloys are of extensive service. Tin plate consists of sheet Fe coated with Sn; if the coat- ing is thick, it is styled block tin. Pins are made of brass wire covered with tin amalgam. Tin-foil is made of Pb between thin strips of Sn. In much of the ordinary tinware the coating USES OF METALS. 105 of Sn is adulterated with Pb, and rusts more quickly than it should. Pure tin-foil is sometimes used as a dental filling. The insoluble Sn0 2 formed between the wall and the filling acts as a preservative. Powdered Sn has been administered to pro- mote the expulsion of worms. Pb is used very extensively in the manufacture of shot, bullets, water-pipes, chemic vessels, dental counter-dies, and various alloys, notably solder and type-metal. Cylinders of Pb have been used for filling the root-canals of teeth. Of secondary importance in manufacture are Mn, Cr, Ni, Co, As, Bi, and Sb. The chief use of Mn is in making ferro- manganese for the Bessemer steel process. Cr is used in the proportion of 0.5 to 0.75 per cent, to harden steel. Ni is utilized as an anti-rust plating for steel and Fe instruments and in armor-plate. The principal use of Co is in making the blue pigment smalt, by fusing some salt of this metal with finely-powdered glass. As ( 1 / 2 per cent.) gives the round shape to bullets. A mixture of Co ("glance") and As is used as fly- stone and black fly-paper. As is also used in fire-works. Bi is employed largely in fusible alloys (safety-plugs), in dies for wood-cut and stereotype impressions, and in dental dies and counter-dies. Sb is used in type-metal because it expands on cooling, and in various other alloys. U salts color glass and render it fluorescent. Mg is of service in photographing objects in dark places; also for flash-lights and signaling, in the Bengal fires and pyrotechnics. It is sometimes substituted for Zn in Marsh's test. K and ISTa, on account of their strong attraction for nega- tive elements, have been used in the separation from their ores of other metals, particularly Mg, Al, B, and Si. Na is a com- mon laboratory reducing agent. Na amalgam is often em- ployed in place of the single metal. On account of its density and wide range of fluidity, Hg is much used in making thermometers, barometers, and other scientific instruments. Its avidity for Au accounts for its use in placer mining. An amalgam of Sn and Hg is used for coat- ing the backs of mirrors. The value of the precious metals Au, Pt, and Ag depends partly on their comparative rarity and partly on the fact that they do not readily fuse or oxidize. Ag is made use of widely in the manufacture of surgical instruments and sutures, being itself slightly antiseptic. It is further used for certain chemic apparatus, for coins, electroplating, the silvering of glass for mirrors, and as the source of Ag salts. Ag coins are alloyed 106 INORGANIC CHEMISTRY. with 10 per cent, of Cu to give the needed hardness. The silver electroplating solution consists of 1 part of AgN0 3 in 50 ILO, combined with 5 KCN in 20 H 2 0; the AgCN thus formed, though insoluble in H 2 0, is soluble in the excess of alkaline cyanid. The Ag bar attached to the + Pl e i s gradually dis- solved by the CN" liberated at the same pole, keeping the pro- portion of AgCIST in the solution about constant. Ag is the most essential ingredient of a good amalgam alloy for filling teeth. Electrolysis of Ag in AgCN is practiced for making base plates for artificial teeth. Au is used as coin and for jewelry, on account of its soft- ness being alloyed with Ag and Cu. The fineness of Au is represented in carats, the pure metal being designated 24 c. fine. United States gold coins are 21.6 c. fine; jewelry usually 14 c. Gilding is performed by means of electrolysis of a solu- tion containing AuCl 3 and KCN. Glass and porcelain are decorated in the same manner or with the purple of Cassius (made by reaction between AuCl 3 and SnCl 2 ). Gold salts are used in photography for fixing and toning. The gold leaf used by dentists and sign-painters is prepared by passing Au between rollers till about V 300 inch thick, then hammering between calf-skin vellum till 1 / 16000 o to 1 / 200 poo of- an inch in thickness. The cohesive Au used for dental fillings is prepared by heating gold-foil to redness, thus restoring the cohesive properties lost by beating, and driving off moisture and gases from the sur- face. Dentists generally employ gold plate of 18 to 20 c. fine- ness, the remaining 4 or 6 c. being made up of from two to six times more Ag than Cu. If a higher carat is desired for greater tenacity (clasps and wires), a little Pt is added, and the Cu exceeds the Ag. Gold plates should be "pickled" in dilute HN~0 :{ after swaging, in order to remove every particle of die metal. On account of its high m.p., Pt is much employed for crucibles, evaporating dishes, stills (H 2 S0 4 ), flame-test wires, and in electric apparatus. An alloy with Ir is harder, less fusible, and less subject to chemic action than is the pure metal. Pt is used to some extent for ornamenting porcelain. It is also employed in dentistry for pins for artificial teeth, for continuous gum-plates, and when finely powdered for coloring artificial teeth. The rare metals are mainly of theoretic interest. Pd is used for mounting scientific instruments and plating silver goods. It is non-magnetic and its elasticity is not affected by changes in temperature, hence it is used in the hair-springs of watches. Va gives a gloss to satin, and is used to set black ALLOYS IN GENERAL. 107 in fabrics. Tungsten or wolfram is used in the manufacture of Welsbach mantles for gas-burners. METALLIC GROUPS. Alkali Metals. This includes K, Na, Li, NH 4 , Rb, and Cs. The group is so called because the oxids, hydrates, car- bonates, and some phosphates of the metals composing it are of an alkaline reaction. All are univalent, and the first three are lighter than H 2 0, which they deoxidize, forming hydrates and setting free H. They are soft, silver-white, easily fusible, and volatilize at high temperatures. They are strongly posi- tive; hence have a great affinity for negative elements. Their salts are all practically soluble, and increase in physiologic potency with the atomic weights of the metals. Metals of Alkaline Earths. These include Ca, Ba, and Sr, and (for present convenience) Mg. They are all diads. They burn readily and decompose H 2 at high temperatures. HC1 and dilute H 2 S0 4 dissolve them. Their halogen salts are freely their sulphates, oxids, and hydrates slightly (except MgSOJ soluble in H 2 0; carbonates, phosphates, and borates insoluble. Lead Group. This comprises Pb, Cu, Bi, Ag, Hg, and Cd. These metals are soft and heavy. Their sulphids are black and insoluble in H 2 0, dilute acids, and NH 4 HS; their halogen salts slightly, if at all, soluble. The carbonate and sulphate of Pb are also insoluble. Aluminum Group. Al, In, Ga. These are practically trivalent. Their double sulphates are called alums. Their oxids are insoluble. Iron Group. Fe, Mn, Co, Ni, Or, Zn. These are divalent or trivalent and more or less magnetic. Their sulphids are soluble in dilute acids. Arsenic Group. As, Sb, Sn, Au, Pt, Mo. Their sulphids are insoluble in dilute acids; soluble in NH 4 HS. ALLOYS IN GENERAL. A combination of metals fused together is termed an alloy; a solution of a single metal in Hg, an amalgam; a solu- tion of an alloy in Hg, an amalgam-alloy. Some of them are probably feeble chemic compounds, forming crystals, but most appear to be mechanic mixtures or solutions. In preparing alloys the least fusible metal should be melted first, and the 108 INORGANIC CHEMISTRY. next least fusible added little by little with constant stirring, preventing oxidation with borax or charcoal, and reducing the heat gradually according to the fusibility of the metal next added. Alloys generally have a lower fusing-point than the mean of their constituents; sometimes lower than any single con- stituent. Alloys of Pb, Sn, Hg, Cd, and Bi are noted for their fusibility. Wood's fusible metal melts at 68; Eose's metal at 94; stereotyping metal melts in boiling H 2 0. An alloy of K and Na is liquid at ordinary temperatures. Fusible alloys are useful in dovetailing teeth into old rubber and celluloid plates with the aid of a warm burnisher. Fluxes are substances added to ores to aid in reduction by lowering the m.p. in this way. Alloys are usually harder than the hardest metal com- posing them. Even the addition of such soft metals as Sn and Pb generally hardens other metals. Cu is added to Ag and Au for this reason. The alloy iridosmine, on account of its hard- ness, is used to tip ("diamond points") gold pens, the particles being pushed into the point of the pen while cold. Al bronze is employed for castings, and is added to steel, Zn, and Ag to improve these metals in hardness and tenacity. Phosphor- iridium, made by heating these two elements together, has great power of retaining lubricants. An alloy with 50 per cent, of Fe is not scratched by the best file. The tenacity of metals is sometimes diminished, but fre- quently increased, by alloying, as illustrated by Al bronze. Steel is 2 */ 2 times as tenacious as iron. The addition of 12 per cent, of Sn to Cu trebles the tenacity of the latter. Sb and As, however, render alloys brittle, and even a trace of Pb makes Au much less ductile and malleable. The color of .alloys is commonly gray, but is sometimes superior to that of their constituents. Thus, brass has a better hue than Cu, is less subject to atmospheric action, and is more easily worked in the lathe. Al bronze resembles Au. Equal parts of Sb and Cu fused together yield a violet alloy. Metallic luster is often modified or even destroyed by alloying. This is particularly true of Au. The sp. gr. of alloys nearly always varies from the average of their constituents. An alloy of Ag and Au is below one of Pb and Sn above the mean of its constituents. Liquation is the term applied to the gravity phenomena whereby the metals composing an alloy form separate layers when the molten mixture is allowed to cool slowly. Pb and Zn, or Pb and Ag, or Cu and Ag can be parted in this way. ALLOYS IN GENERAL. COMMON ALLOYS. 109 NAME. PARTS IN 100. d SILVER. COPPER. fc H g N G < d ALUMINUM. NICKEL. ANTIMONY. BISMUTH. MEKCURT. SPELTER. CADMIUM. 1 MANGANESE. i PHOSPHORUS. U. S. Gold Coins . . U. S. Silver Coins . Green Gold .... Red Gold Niirnberg Gold . . 90 75 75 2.5 90 25 10 10 25 90 84 5 15.5 20 33.3 6 5 1 7.5 10 20 20 25 1 German Silver . . 60 66.6 91 90 75 90 80 90 88 ' 9 1.84 85 2 Aluminum Bronze Manganese Bronze Phosphor-bronze . Bell-metal 9 20 10 73 81.9 15 80 12.5 75 2 10 2.5 18 16.25 Gun-metal .... Hercules Metnl . . Babbitt-metal . . . Britannia Pinchbeck 20 Pewter 16 5 67 16.5 50 50 4 20 31 80 12 5 19 25 Fusible Alloy Rose's Metal . . . Soft Solder .... Plumber's Solder . I>ental Solder 25 60 33.3 45 25 40 66.6 ! -H 50 10 40 401- - 20 Brass Solder . . . Silver Solder . . . 73 9 75" 9 4 4 25 18 Gold Solder .... Aluminum Solder . 83 90 r 6 Bronze. a Brass. 110 INORGANIC CHEMISTRY. When metals differ greatly in fusibility it is best to unite first those that combine most readily. The property of sonorousness, in which most single metals are deficient, is much enhanced by alloying. Examples are bell-metal and an alloy of Cu and Al. Elasticity may sometimes be increased by adding a small proportion of other metals. "Spring gold" contains a small percentage of Pt. Alloys of Zn or Hg and other metals are accompanied by heat. The specific heat of an alloy is the mean of the specific heat of the component metals. Conducting-power for heat and electricity is generally reduced in alloys. The coefficient of heat-expansion in alloys is usually about the average of their ingredients. An exception is copper-tin alloy, which expands less than pure Cu, although Sn alone expands more than Cu. The solubility of alloyed metals is often considerably altered. Thus, Ag becomes insoluble in HN0 3 when alloyed with more than 25 per cent, of Au, and Pt becomes quite sol- uble in HN0 3 when alloyed with Au or with ten times as much Ag. Alloys of Sn and Pb and the tin-silver amalgam-alloys used for filling teeth are readily tarnished or oxidized. Experiment. Dissolve a 10-cent piece in HNO 3 . What color is produced, and why? Dental amalgam-alloys, used for fillings, are usually com- posed of 65 (40) parts Ag and 35 (60) parts Sn. This type may be modified by the addition of a few per -cent, of spongy Pt, Cu, Au, Zn, Pd, Al, Sb Fe, or Cd. The advantages of an amalgam-alloy over a simple amalgam are that opposite prop- erties for instance, expansion and contraction may neutral- ize each other, and also help to set more quickly. An amalgam may be prepared (1) by bringing the metal or alloy in contact with Hg; (2) by adding Hg to the molten alloy; (3) by action of the metal on a salt of Hg; (4) by action of Hg on a salt of the metal. The third method is illustrated when metallic in- struments are immersed in HgCl 2 solution. The time of setting varies from hours to days, according to the ingredients and whether the excess of Hg has been squeezed out or not, using chamois or good muslin. Discoloration of amalgam fillings is due to H 2 S from de- composing food in the mouth. Ag, Cu, and Pd are blackened; Cd turned yellow. The Ag 2 S thus formed is antiseptic, serving to preserve the teeth. The discoloration of gold fillings is said to be due to oxidation of the steel worn from pluggers. Gal- vanic action between the ingredients of fillings may also have ALLOYS IN GENERAL. HI something to do with their discoloration and disintegration, especially when Cu is present. Cu amalgams waste, because the black oxid and sulphid on the surface change to the soluble sulphate. Al amalgam in the presence of moisture swells up and decomposes into A1 2 3 and Hg, with production of heat. The black "dirt" that is given off in mixing ordinary amalgam-alloy is a lower oxid of Sn, and is more abundant after annealing. Pressure on solid amalgams causes a yielding or flow, which varies with the amount of stress. "Electric amalgam" is commonly prepared with 1 part each of Sn and Zn and 3 parts Hg. Dental solders are special alloys for joining metallic sur- faces. They usually consist of the metal to be soldered, with another to lower the fusing-point. Hard solders fuse at or above red heat; soft solders below this point. By autogenous soldering is meant the fusing together of contiguous parts of the same metal, usually Pb or Pt. Soft solders are used in the stick form; hard solders in ingot filings; Au and Ag solders as clippings from rolled sheets. They are prepared in a crucible in the same manner as other alloys. The best tin solder for dental use contains 1 Pb and 2 Sn, and melts at 171. Bi solders are composed of Bi, Sn, and Pb, and melt at from 95 to 160. Eeally good Al solders are not to be had at present. As a dental solder Hall recommends a combination of 45 parts each of Al and Sn and 10 parts Hg, the solder being applied with a brazing blow-pipe and a piece of steel wire. Fused AgCl is used as a flux. Al bronze is readily soldered with alloys of Au, Ag, and Cu. Brass solder is hard, and varies from yellow to white ac- cording to the amount of Sn. Silver solders consist of Ag alloyed with Cu, Zn, and Sn, and are used in soldering Ag, German silver, brass, cast-iron, and steel. For general use an alloy of 8 Ag, 1 Cu, and 2 Zn is recommended. For soldering steel 3 parts Ag and 1 part Cu is mentioned by Brannt. Gold solders range from 12 to 20 c. in fineness, the re- mainder being made up of Ag and brass in nearly equal pro- portions. For crown and bridge work Essig commends a solder containing 20 Au, 2 Ag, and 1 each Cu and spelter (equal parts Cu and Zn). Soft solders are generally applied with a clean and tinned Cu bit. A brazing blow-pipe is used for hard solders. The surfaces to be united are commonly "pickled" in dilute HC1 or H 2 S0 4 . Rosins or soldering fluids., such as a saturated solu- tion of Zn in HC1, are employed with soft solders as protective fluxes. A thin paste of borax and H 2 is used, as a rule, with 112 INORGANIC CHEMISTRY. hard solders. The oxidizing flame should be avoided in solder- ing. Dental dies are made of Zn or babbitt-metal (1 Cu, 2 Sb, and 8 Sn), Spence's metal (FeS melted in S), or type-metal (1 Sb, 1 Sn, and 4 Pb). Alloys for counter-dies usually consist of 1 part Sn and 7 parts Pb. Fig. 21. Apparatus for Determining the Melting-point of a Solid. Experiment to Determine the Melting-point of a Fusible Alloy. Place alloy in a test-tube, to which is bound a thermometer, and im- merse both in a beaker of H,0. Heat the H 2 0, with constant agitation over a hot plate, till the alloy melts. Then let cool and note tempera- ture at which the alloy solidifies. If the alloy does not fuse at or below the b.p. of H 2 O, raise this point by saturating with NaCl or NH 4 C1 or by using some liquid (glycerin or H 2 S0 4 ) with a higher b.p. than H 2 0. HYDROGEN. 113 METALLOIDS. These elements differ from the metals by taking generally the electronegative role. Their oxids are acid in reaction. Some of them are gases, one (Br) a liquid, and a number solids. HYDROGEN. Though, strictly speaking, a gaseous metal, H will, for con- venience, be considered with the metalloids. The element is so called because, in connection with 0, it forms water. It was first observed by Paracelsus in the sixteenth century. It was carefully investigated by Cavendish in 1766, who termed it inflammable air, and later demonstrated that it formed H 2 with half its volume of 0. H occurs free in Nature in small quantities, occluded in meteorites, in carnallite, and in volcanic and other natural gases. It is one of the products of decomposition of organic substances, and hence is found in the lungs, stomach, and in- testines, and in sewer-gas. It is believed to be the chief con- stituent of the solar atmosphere. The compounds of II with other elements are very numerous and important, including water, ammonia, marsh-gas, all acids and acid salts, hydrates, and most fuels and substances used for lighting, as well as sugars, starches, and hydrocarbons. It may be prepared from H 2 by electrolysis or by the action of metals (Na, for example) that have a great affinity for 0. The usual method of production is by treating granules, of Zn with diluted (1 to 5) H 2 S0 4 or HC1: Zn + H 2 S0 4 + H 2 = ZnS0 4 + H 2 + H It is collected by displacement over water. The process of evolution is hastened if an inert, more electronegative sub- stance, such as Cu or PtCl 4 , is immersed in the fluid. H is also evolved on heating certain metals (Zn, Mg, and Al) with strong solutions of alkaline hydrates. H is a colorless, odorless, tasteless gas. It is the lightest substance known; hence is taken as the unit of atomic weight and density. Air is nearly 15 times as heavy. A liter of H at and 760 mm. pressure weighs a crith: equivalent to 0.0896 gm. H is the most difficult of gases to liquefy, having been condensed by Dewar in 1898 to a steel-blue liquid under a pressure of 600 atmospheres at 140. This liquid is the lightest known (sp. gr., 0.07) and boils at 238. H is the 114 INORGANIC CHEMISTRY. most diffusible of gases, has the greatest specific heat (3.4), is the most refractive of gases, and the best gaseous conductor of heat and electricity. One volume of the gas dissolves in 50 of water. It is readily absorbed or occluded by a number of metals, particularly Pt and Pd (forming an alloy), the latter metal taking up 400 volumes of the gas, and the former (in the finely divided or spongy state) has so great an avidity for this gas as to ignite it through the heat produced by its rapid absorption. Experiment. Make H and pass gas on to a disk of spongy Pt till ignition takes place. In its chemic relations H generally plays the positive role, especially in acids, and is displaced from its combinations by Fig. 22. Preparation of Hydrogen. metals which are more electropositive. H is not a supporter of combustion, and at ordinary temperatures has little affinity for 0, but is quite combustible at elevated temperatures, burn- ing with a pale-blue flame and forming H 2 0; when mixed with air or 0, it explodes with violence. On account of its avidity for and other non-metals, heated H is a powerful reducing agent. Nascent H unites with solutions of As and Sb to form inflammable gaseous compounds. H gas is neither noxious nor beneficial physiologically. It can be inhaled for a short time without injury, producing only a peculiar change in the voice: i.e., a higher pitch, due to more rapid vibration of vocal cords in rarer atmosphere. HALOGENS. 115 Experiment. Make H and show properties of combustibility, but not supporting combustion, levity, and diffusibility. Take care to expel all air from iiask before igniting. Test. O + H 2 = H 2 O, shown by holding cool glass vessel near burning jet. Combined with by means of the oxyhydrogen blow-pipe, it yields a very intense heat, sometimes used for fusion and reduction purposes. Reduced iron, or Fe by H, is prepared in this manner. H was formerly utilized for balloons, having a lifting power of a little more than one ounce to the cubic foot, but has proved too diffusible to be of much service in this con- nection. HELIUM. This gaseous element was first discovered in the solar atmosphere by means of the spectroscope, in which it shows a yellow line at D 3. Recently it has been shown to be oc- cluded in many minerals, often accompanied by H, and is also present in the gases of certain springs and to a very slight extent in the air. It is a very inert substance, and extremely difficult to liquefy. HALOGENS. This group is so called because most of its members can be derived from sea-water and plants. Its members form binary salts by combining directly with metals. It includes four elements, two of which, Cl and F, are gases; Br, a liquid; and I, a solid. All are strongly electronegative, neutral, and generally univalent. They have a sharp, acrid taste, and a characteristic irritating odor; they corrode metals, combine with H to form colorless acid gases, and act as bleaching and disinfecting agents. Their relative combining energy is in- versely to their atomic weights. They can all be prepared (except F) by removing H from their acids by means of derived from Mn0. 2 . Experiment. Drop a few grains of MnO, into three test-tubes. Then add to the first a little powdered NaCl, to the second NaBr, and to the third KI. Next pour into each a few drops of H 2 SO 4 and warm. Note formation of Cl in the first tube, Br in the second, and I in the third. Fluorin. F was first isolated with electricity by Moissan in 1886. Its name is derived from the principal natural com- pound, fluorspar, CaF 2 . This element occurs very sparingly in a free state, but as CaF 2 it is found nearly everywhere. Cryolite (N"aFAl 2 F 6 ) is 116 INORGANIC CHEMISTRY. a porous rock abundant in Greenland. F is also present in sea and mineral waters, bones, teeth, and milk. F is a colorless gas, so powerful in its affinities for other substances that it can be prepared only by electrolysis of HF in vessels of Pt or CaF 2 . It is the only element that does not combine with 0. Fig. 23. Preparation of Chlorin. Chlorin. This element was first prepared by Scheele in 1774, and was so named by Davy because of its greenish color. Cl never occurs free in Nature, but in combination with other elements it is of almost universal distribution. For laboratory or medical use it is usually prepared in one of the two ways indicated by the following equations: HALOGENS. 117 Mn0 2 + 4HC1 = 2H 2 + MnCl 2 + C1 2 (U. S. P. method) CaCl 2 + 2HC1 = C1 2 + CaCl 2 + H 2 It will be noted in both instances that the H of HC1 is oxidized and Cl set free. Experiment. Make and collect the gas dry (by downward dis- placement) and in tLO. Cl is a greenish-yellow gas of a peculiar, penetrating, suf- focating odor and acid, astringent taste. It is 2 1 / 2 times as heavy as air, and can be condensed to an oily liquid by 4 atmos- pheres at ordinary temperatures. One volume of water absorbs nearly 3 volumes of the gas. Aqua chlori, thus obtained, should contain not less than 0.4 per cent., by weight, of Cl. Cl water should be protected from air and light, as otherwise it changes to HC1. Cl is highly electronegative; hence has affinity for most other elements, especially H and other metals. The gas pre- pared in daylight is much more active than that made in the dark. Experiment. Mix equal volumes of H and Cl in a flask, and show that the color disappears with chemic combination and that the volume of the HC1 formed equals that of both gases. Experiment. Fill one test-tube with H and another with Cl. Place mouths of tubes together (Cl above) and hold in sunlight or near a flame. An explosion results. H burns freely in Cl and Cl in H. This fact may be shown by holding a candle in a jar of Cl; the C of the candle is un- burned and produces a dense cloud of smoke. Experiment. Throw a piece of paper wet with warm turpentine (C 10 H 1G ) into Cl. Explain spontaneous combustion and dense smoke. Experiment. Show affinity of Cl for Sb by dropping some finely powdered Sb into a jar of the gas. It burns and is converted into a white powder: SbCl 3 . On account of its affinity for H, Cl acts as a bleacher (for cotton, linen, paper, and discolored teeth), deodorizer, and dis- infectant: i.e., freshly generated Cl unites with the H of H 2 and sets free nascent 0, which is the really active agent in destroying colors, odors, or germs and their products. It is evident that these changes can take place only in the presence of moisture. Experiment. Show decolorizing action of Cl water on calico, and that the dry gas has little effect in this direction. Cl tarnishes and corrodes all metals, and is the solvent of Au and Pt in aqua regia. 118 INORGANIC CHEMISTRY. Experiment. Immerse a strip of Cu foil in Cl water, and note how quickly it blackens; also dip a knife-blade into solution of HgCl 2 . Bromin. This element was first discovered by Balard in 1826, and owes its name to its strong odor. It occurs naturally only in combination with Mg and the alkali metals, accompany- ing the chlorids. It is separated from the mother-liquor (bittern) of sea- water from which NaCl has been removed by evaporation and salt-wells and springs by treating the liquid with Cl. This element, being more negative than Br, has a greater affinity for metals, and drives Br from its metallic combinations, setting it free. Experiment. Shake KBr with Cl water and then chloroform, and note that the latter takes up free Br and is colored red. Br is a dark-reddish-brown liquid, very volatile (fuming), and corrosive. It is 3 times as heavy as H 2 0, in which it dis- solves to the extent of 3 per cent.; it is more freely soluble in alcohol, ether, or chloroform. Br is less energetic than Cl, but more so than I. Solu- tions of the element are decomposed by light, with formation of HBr. It stains organic matter yellow. Great care should be taken not to allow the fumes to corrode surgical instruments or the metallic parts of the microscope. If the hands get burned with the substance, NH 4 HO ought to be applied at once. Though strongly germicidal, Br is seldom used as a dis- infectant, because of its many disadvantages. Its chief use is in the manufacture of hypobromites. lodin. I was discovered in 1811 by Courtois, a Parisian soap-boiler, in "kelp," or the ashes of sea-weeds. The name signifies violet. I is found widely disseminated in the three kingdoms of Nature, though not abundant except in marine plants (espe- cially laminaria), which absorb it from the sea-water, as do also the salt-water fishes, which accounts for the appreciable amount of I in codliver-oil. I is prepared from sea-weed ashes (variously known ac- cording to locality as kelp, varec, and barilla) by lixiviation and evaporation to concentrate, followed by the addition of H 2 S0 4 to the mother-liquor (ppts. S), and finally distillation of the remaining clear liquid in the presence of Mn0 2 . 2KI + Mn0 2 + 2H 2 S0 4 == K 2 S0 4 >f MnS0 4 + 2H 2 + I 2 The product thus obtained is usuaHy purified by resub- limation. OXYGEN. 119 This element is met with in the form of brittle, neutral, volatile, crystalline, purple scales, with a distinct metallic luster and a peculiar odor and disagreeable taste. Its sp. gr. is nearly 5; m.p., 114; b.p., 180. It is very slightly soluble in H 2 0, requiring for 1 part over 5000 of the latter. Its solution in H 2 is greatly aided by the presence of tannin or KI. LugoPs solution (liquor iodi comp.) is composed of 5 I and 10 KI in H 2 to make 100 parts. I is freely soluble in alcohol (tincture, 7-per-cent. strength), glycerin, ether, chloroform, and CS 2 . The solution in alcohol is brown; in chloroform or CS 2 , violet. Experiment. Heat I and notice beautiful violet vapor. I is the least energetic of the halogens. It attacks some metals, however, to a marked degree; its solutions should not be handled in Ag spoons. It stains the skin brown. It is an irritant, an antiseptic, and a valuable alterative. Test. With hydrated starch I gives a blue color, showing as little as 1 part of I in 300,090. On heating the color disappears, returning on cooling if not all volatilized. I is used in medicine, in photography, and in the manu- facture of iodids and some of the coal-tar colors. Experiment. To CS 2 add S and an aqueous solution of I, and note violet beads of SI 6 . OXYGEN. This element was so named from a Greek word meaning sour or sharp, because it was formerly believed to be an essen- tial element of all acids. It is the most abundant element in Xature, making up nearly 1 / 2 of the earth's crust. It occurs free as the active agent in air, of which it forms about Y 5 . constitutes by weight 8 / 9 of H 2 0, x /2 of sand, and Vs of clay- It is a constituent of nearly all organic compounds, except hydrocarbons, and is found in combination in every part of plants and animals. It was discovered by Scheele in 1773. is usually prepared for experimental purposes by heating 4 parts KC10 3 at 200 with 1 part Mn0 2 . 2KC10 3 + Mn0 2 = 2KC1 + 30 2 + Mn0 2 Experiment. Manufacture O in a copper retort, and collect over H 2 0. ., As seen by the enuation, Mn0 2 remains apparently un- changed A reaction which is induced or aided by the mere presence of another substance is said to be catalytic in nature. 120 INORGANIC CHEMISTRY. When the Mn0 2 is not employed, a higher temperature (325) is necessary. The presence of the Mn compound also makes the evolution of the gas more steady and regular. A pound of KC10 3 will yield 60 or 70 quarts of the gas. On a large scale is manufactured by the Brin -process, which consists in heat- ing to 700 porous BaO in retorts into which pure air is forced. Ba0 2 is formed, which gives off on reduction of pressure. is a colorless, odorless, tasteless gas a little heavier than air: a liter weighs 1.43 gm. It is difficultly liquefied, requiring a pressure of 300 atmospheres and a reduction of temperature to 140, when it condenses into a transparent liquid, a little lighter than H 2 0. The critic temperature of is 120. It dissolves in H 2 to the extent of 3 per cent, by volume, and it is from this source that aquatic plants and animals obtain the necessary to their existence. is the most magnetic of all gases. Experiment. Occlude O with Pt black, pour on alcohol, and note ignition. unites with every element except F (not directly with Au, Pt, and Ag), forming oxids and oxysalts. This union is termed oxidation, or "slow combustion," unless light as well as heat results, when the process is known as combustion. Substances readily oxidized are said to be combustible and are composed mainly of C and H, the C being converted into C0 2 , and H into H 2 0. The C0 2 and H 2 given off by the lungs and urea by the kidneys are produced by oxidation in the tissues. Plants take up this C0 2 in sunlight, keep C, and set free 0. Artificial heat, light, and mechanic energy are produced mainly by oxidation. Experiment. With a glowing match show that is a supporter of combustion, but not combustible. Some substances burn in O that will not burn in air. Experiment. Burn a watch-spring in O, after attaching to one end a match by spiral turns. Combustible substances and supporters of combustion are relative terms, since the union of two such substances is mu- tual. Air or can be made to burn in illuminating-gas by a simple device consisting of a lamp-chimney with a bottom cork through which two glass tubes pass, one to admit air, the other illuminating-gas. When the gas is passed in freely, the flame leaves this tube and goes to the air-tube. is the chemic source of heat, energy, and life for both plants and animals. About two pounds daily are used up by an adult person in this way. Plants use less than animals, SULPHUR. 121 having less energy, and set free a great deal more than they consume. Animals require a large amount of 0, giving off C0 2 in return. The principal subjective effect when pure is in- haled is a sensation of warmth in the upper respiratory tract. is Nature's great antiseptic, purifying the air, water, and soil by destroying the germs of disease and their chemic products. is used largely in respiratory or circulatory affections with deficient oxygenation of the blood. It is also administered by inhalation for dangerous chloroform narcosis and poisoning by coal-gas and other noxious vapors. In chronic cases 1 to 5 gallons is a dose. is also of service in the oxyhydrogen blow-pipe, in purifying illuminating-gas (removes S), and in the preparation of paints and varnishes and the artificial "aging" of spirits. Ozone. This peculiar allotropic form of exists in the atmosphere in comparatively small quantities: about 1 part in a million. It is generated by heat, light, and electricity; slow oxidation, rapid combustion, or exposure of essential oils to sunlight and warmth. It is most abundant at high altitudes, in country places, after thunder-storms, in the spring-time, and in the neighborhood of plants. Ozone is triatomic. It may be condensed into a blue liquid. It is soluble in turpentine or ether, and breaks up into 2 and at 237. Like H 2 2 , it tarnishes metals and corrodes cork and rubber. It is used as a bleaching agent and for "aging" liquors. The word ozone is of Greek origin, and signifies "I smell." The characteristic irritating odor of the substance may be elicited by dipping a strongly-heated glass rod into vapor of ether, or by mixing H 2 S0 4 with K 2 Mn 2 8 solution, or around medical batteries or x-ray machines. Experiment. A simple test for ozone is hanging a piece of starch- paper impregnated with KI over a piece of P partly covered with ELO. Ozone, being more negative than I, displaces the latter, producing a blue color with the starch. SULPHUR. This element has been known from the earliest times. In a free state, mixed with earthy matters, it is found most abun- dantly in the vicinity of active and extinct volcanoes, having been formed by the following reaction: S0 2 + 2H 2 S = 2H 2 + S 2 In combination it is almost universal in the sulphids of the metals, and is also of common occurrence in the H 2 S of 122 INORGANIC CHEMISTRY. mineral waters, the sulphates of the alkalies and alkaline earths, and in animal and vegetable compounds. About a third of the S of commerce is derived from sul- phid ores. The remainder comes from volcanic regions, espe- cially Sicily and other Mediterranean countries, which furnish annually 100,000 tons. A great deal is obtained from Iceland, Mexico, Central America, the Sandwich Islands, and in this country Santa Barbara, Cal., and Cove Springs, Utah. It is also a considerable by-product in the manufacture of coal-gas, from the iron-pyrites in the coal. Fig. 24. Sublimation of Sulphur. S is separated from accompanying impurities (2 or 3 per cent.) by melting along with a little fuel in furnaces with in- clined grooved bottoms, where the S solidifies into rolls; hence the name roll sulphur for brimstone (burnstone). It is further purified by sublimation, the vapors condensing in a cooler chamber into sublimed S, or flowers of S. Ordinary S is a lemon-yellow, odorless, nearly tasteless, brittle, crystalline solid (rhombic octahedra or monoclinic). It is insoluble in all the ordinary solvents except benzin, turpen- tine, chloroform, fixed oils, and CS 2 ( 10 % 7 ). The sp. gr. of S TELLURIUM. 123 is about 2; its m.p., 114 Y 2 ; b.p., 448. Melted S allowed to cool slowly assumes a prismatic form. When melted it is a thin, yellow liquid, becoming thick and brown at 250, turning lighter again at 330. Melted S at about 400, poured into H 2 0, forms an amber-colored, elastic, tenacious mass termed plastic S. This variety is amorphous, and not soluble in CS 2 . Experiment. Make plastic & by melting S in covered vessel and pouring into H 2 0. S is generally electronegative, and in ternary compounds may take the place of as a linking agent. Its vapor density below 500 is 96; between 800 and 1000, 32. At ordinary tem- peratures S oxidizes slowly, forming H 2 S0 3 and H 2 S0 4 . It burns with a blue flame at 230, forming S0 2 . S combines with most metals and with many metalloids. Physiologically S is innocuous. Sublimed S is used largely as a vulcanizing material. For dental rubbers caoutchouc is heated till soft, then ground with 15 or 20 per cent. S and subjected to heat, pressure, and moist- ure. S is employed extensively in the manufacture of gun- powder and matches. Medicinally it is serviceable as a laxative (in compound licorice-powder) and in parasiticide ointments; the latter action is attributed to the S0 2 present in sublimed S. Plastic S is used for taking impressions. The official forms comprise: 1. S sublimatum (ordinary S). 2. S lotum, or washed S, from which the acid gases have been removed with NH 4 HO. 3. S precipitatum, or lac or milk S, a whitish, amorphous powder prepared by the successive action on S of lime and dilute HC1. 4. Unguentum sulphuris, which contains 30 per cent, of S sublimatum. SELENIUM. This element is widely distributed, though in small quan- tities, usually associated with S. It appears as an amorphous, brick-red powder, soluble in CS 2 ; and as a crystalline, dark- gray solid, insoluble in CS 2 . The element burns with a bright- blue flame and an odor like that of horse-radish. TELLURIUM. This rare element is found free or combined as tellurids with Au, Ag, and other metals. It resembles metals in being solid and silver-white. It burns in the air with a blue flame tinged with green. Tellurids are recognized by fusing with KoC0 3 . The resulting K 2 Te dissolves in H 2 with a red color, and on adding HC1 yields a stench of H 2 Te. 124: INORGANIC CHEMISTRY. NITROGEN, OR AZOTE. This element was first discovered by Rutherford in 1772. It was so named because it is an essential element of niter, or saltpeter. Free N" constitutes about four-fifths of the atmos- phere. In combination it is the characteristic element of nearly all animal substances and their decomposition products, am- monia, nitrates, nitrites, and cyanids. It is also present in a number of vegetable compounds. Experiment. Burn P on a cork on water under a bell-jar. The is removed, forming dense, white fumes of P 2 5 , which is absorbed by the water, and N is left. Pure N is prepared by heating N"H 4 N0 2 in a glass retort, or KN0 2 and NH 4 C1. Fig. 25. Preparation of Nitrogen. N is a colorless, odorless gas, a little lighter than air. It liquefies at 130 under a pressure of 280 atmospheres. One and a half volumes of the gas dissolve in 100 of water. N is neither combustible nor a supporter of combustion. Experiment. Raise lighted candle into jar of N. N is chemically inert and has little affinity for other ele- ments, except Mg, B, Y, and Ti. Its compounds are there- fore unstable, decomposition often taking place with explosive violence. The passive nature of N accounts for the active and dangerous character of its compounds, such as nitroglycerin and nitrates, as well, perhaps, for the physiologic potency of the cyanids, alkaloids, and other nitrogenous products. It is even possible that on this same property depends the difference THE AIR. 125 between the dispositions of carnivorous and herbivorous ani- mals. N gas, though non-poisonous, is not directly utilized by the system. Its presence in inhaled air is needed to prevent too rapid oxidation of the tissues. N is occasionally employed as a medium for chemic processes from which must be excluded. Experiment. Make NI 3 by treating tincture of iodin with excess of NH 4 HO. Collect ppt. on filter-paper and put a few grains on several separate bits of paper. On drying it explodes at the slightest touch. THE AIR. Until 1772 air was considered to be an element. Air is a mechanic mixture, and not a compound. This is proved by the facts that its constitution is not absolute, that when ab- sorbed by H 2 the N and are not in the same proportion as in the atmosphere, and that there are no chemic phenom- ena on mixing N and 0. The principal gases in air are and 1ST, in the proportion, by weight, of 23 per cent, of the former and 76 per cent, of the latter; by volume, 20.61 per cent, of and 77.95 per cent, of N. Argon constitutes about 1 per cent, of the atmosphere, and was discovered by Kayleigh and Eamsey in 1894 by removing from air both the (with red- hot Cu turnings) and the N (with red-hot Mg) as well as H 2 and C0 2 . Argon is the most inert element known, and its name signifies no energy. Helium is another gas lately discovered in our atmosphere (1 to 10,000), and already noticed in the solar spectrum; hence its name. Coronium is another atmospheric gas, found in volcanic vapors, and showing a characteristic green line in the solar spectrum. It appears to be lighter than H, and both this element and He may be compounds of H, which also exists in the atmosphere in traces: 2 parts in 10,000. Krypton is the latest discovered atmospheric element, found in the residue left from liquefying A. There are also traces of neon and metargon. All of these minor gases are monatomic and inert. Water-vapor is present in air to the extent of 0.75 to 1.5 per cent. (3 to 16 volumes per 1000). C0 2 in the atmosphere should not exceed 4 parts in 10,000. Liquid air is now made on a commercial scale by machin- ery. The air is subjected to a pressure of a ton to the square inch, and at the same time allowed to escape through a very fine orifice. Much heat is absorbed in expansion, and by re- peating the operation three times the temperature is lowered 12(3 INORGANIC CHEMISTRY. to or below 191, at which point liquefaction takes place. Liquid air is faintly blue. In open vessels it evaporates rap- idly; the N", being somewhat more volatile, is given off more rapidly than 0. Even at this temperature of about 200 the residue is an energetic supporter of combustion. Soft and elastic organic substances and metals become very brittle when immersed in this fluid. Liquid air has been used to some ex- tent in medicine as a caustic application: e.g., in lupus. In the future it is likely to find very extensive use as a cooling agent for rooms in hot weather. The density of liquid air is 0.9. According to Hinrichs, the real atmosphere, containing aqueous vapor and clouds, forms a stratum 12 miles in height. Its density decreases with increase of altitude, as shown by the barometer. At the ocean-level air is 14.44 times as heavy as H, and a liter weighs 1.29 gm. The atmosphere reaches to 30 miles, at which height is reduced to 10 per cent. The N" atmosphere (reduced from 86 per cent, to 4 per cent.) extends to 60 miles above the earth. The He, or auroral, atmosphere is the fourth stratum, and gradually gives way to H, which at a height of 100 miles constitutes 90 per cent., by volume, of the air. PHOSPHORUS. The word phosphorus means the light-bearer and indicates the combustible nature of this element. P was discovered in 1669 by the German alchemist Brandt, by distilling urine with sand. This element does not occur free in Nature. It was pri- marily combined with in the ancient rocks, which on dis- integration furnished P for plants, and these to animals. The principal natural compound is rock phosphate, Ca 3 (P0 4 ) 2 , which is made up largely of the bones of prehistoric animals. It is found in veins in the rocks of certain regions, especially near Charleston and Memphis, and is also present in small amounts everywhere. P is prepared by treating bone-ashes or the mineral som- brerite [impure Ca 3 (P0 4 ) 2 ] with an equal volume of 50 per cent. H 2 S0 4 , yielding CaS0 4 and CaH 4 (P0 4 ) 2 . The latter salt on heating to redness loses two molecules of H 2 0, and is thereby changed into the metaphosphate, Ca(P0 3 ) 2 , which is, in part, reduced to P by charcoal with the aid of a white heat or by distilling with sand. The crude P thus obtained is puri- fied by redistillation, and is allowed to solidify in molds of glass or Cu. PHOSPHORUS. 127 This element has four allotropic forms: two white, a red, and a black. The ordinary stick, or white, octahedral P is of a translucent, waxy appearance; sp. gr., 1.83; m.p., 44. It can be cut with a knife, and has a characteristic odor. It is in- soluble in H 2 0, slightly soluble in ether and in alcohol (1 to 350), and quite soluble in chloroform. The best practicable solvents for it are fixed oils (1 to 50), though CS 2 is most effi- cient, dissolving 20 times its own weight of P, the solution being spontaneously inflammable on exposure to the air. Eed, or "amorphous," P is prepared by heating the ordi- nary variety at 300 in a closed iron vessel filled with N or C0 2 . It is generally insoluble, not so inflammable as the white variety, and has a sp. gr. of 2.14. It is reconverted into ordi- nary P on heating to 280. The third variety called black, or metallic, P appears in the form of dark-red, rhombohedral crystals; sp. gr., 2.34. It is made by heating waxy P along with Pb at a little below red heat in sealed tubes for 10 or 12 hours, after which the Pb is dissolved out with dilute HN0 3 . A fourth variety, white and flaky, is prepared by distilling ordinary P in an atmosphere of H. Ordinary P is very oxidizable, igniting spontaneously in air at from 50 to 60. At lower temperatures it oxidizes more slowly, with phosphorescence. To prevent spontaneous com- bustion, it is kept under H 2 0. When partly exposed to the air it evolves white fumes of P 2 5 , and also ozone and H 2 2 . P combines directly with all the common elements except C, H, and N. Red P is much more inert than the white, not igniting below 260. The black variety is the least active. Experiment. Make fire under water by placing in a conic glass of H,O a few bits of P and some crystals of KC1O 3 , adding to these by means of a pipet some H 2 SO 4 . Experiment. Make H 3 P by boiling P with KHO, first expelling air in the flask by dropping in a few drops of ether. Keep the beak of the retort under water, and note how the bubbles ignite as they appear at the surface and the curious rings of P 2 O 5 that are formed. Phosphin, H 3 P, is a colorless gas with an odor like garlic, formed in Nature by the putrefaction of organic substances under water. When mixed with P 2 H 4 (a liquid) it is spon- taneously combustible. This is the ignis fatuus, or will-o'-the- wisp, of marshy places. P and its compounds are used extensively in medicine for building up the bony and nervous tissues. P matches are made by dipping the wooden slips tipped with paraffin or S in a mixture of glue and P, to which have been added other in- gredients such as Mn0 2 , KN0 3 , chalk, S, lamp-black and 128 INORGANIC CHEMISTRY. other oxidizers, combustibles, and hard substances to increase friction. Parlor-matches crackle because of the quick com- bustion, due largely to KC10 3 . Safety-matches contain no P, but Sb 2 S 3 , Pb 3 4 , and KC10 3 , or K 2 Cr 2 7 . In order to ignite them they must be rubbed on a surface composed of red P and Sb 2 S 5 . The gritty nature of the latter compound makes the friction greater. Eed P is slightly, if at all, toxic, and is used in Europe for making matches, in place of the white variety, which is still employed almost exclusively in this country. A simple test for P is to heat in a test-tube with acidulated water, and note the phosphorescence. Filter-paper dipped in AgN0 3 , held above the mouth of the tube, is colored dark by formation of silver phosphid. The official preparations of P are three in number. Oleum phosphori contains 1 per cent, of P dissolved in sweet almond- oil. Pilule phosphori contain Yioo grain of P, and are coated with balsam of Tolu. The spirit or tincture of P is made with absolute alcohol, and has 1.2 parts of P in a thousand. BORON. This element was first isolated by Davy in 1808. The name is derived from an Arabic word meaning to shine, and referring to the incrusted shores of borax lakes. It is found in the natural state only in combination, chiefly as borax and boric acid. B appears as a brown or yellow, amorphous powder or octahedral crystals. These crystals are infusible and next to the diamond in hardness, and have a sp. gr. of 2.68. At high temperatures B combines directly with N. SILICON, OR SILICITJM. This element was so called from the Latin word silex 9 meaning flint. It was first isolated by Berzelius in 1823. Next to 0, Si is the most abundant element in Nature. It is never found free. It is the chief constituent of nearly all rocks and soils, and is present in plant-ashes and to a much less extent in animal tissues. Si may be prepared by heating together K 2 SiF 6 and K 4 . When thus obtained it appears as dark, lustrous octahedra,. hard enough to scratch glass, and with a sp. gr. of 2.5. It may also be procured in amorphous and graphitic forms correspond- ing with those of C. CARBON. 129 CARBON. C in all its forms was known to the ancients. Its name is derived from carlo: Latin for charcoal. C is found in Nature in three allotropic forms: two crystal- line (diamond and graphite), one amorphous, including coal, charcoal, coke, lamp-hlack, and gas-retort carbon. The dia- mond is the hardest substance known. It is 3 1 / z times as heavy as H 2 0, and crystallizes in cubes or octahedra. Its brilliancy depends on internal reflection of light, owing to its great refractive power. The best diamonds are found in the gravel-beds of Brazil and South Africa. These are worn as gems; small and imperfect ones are used in glass-cutters, miners' drills, and rock-boring machines. Microscopic dia- monds are found in steel made by the Bessemer process. The carat, or special unit of weight for diamonds, is equal to 3.17 grains. Graphite (plumbago, black lead) crystallizes in unctuous hexagonal prisms; sp. gr., 2; is almost infusible, and is a good conductor of electricity. On account of its non-oxidizability, this substance is much used as a protective and lubricant: e.g., in stove-polish and for machinery and bicycle-chains. It is also used in painting metals, electrotyping, glazing, gunpowder, as a mold-wash, and mixed with clay and sand in crucibles. It owes the name graphite to the use which is made of it in pen- cils. The best quality is from a mine at Cumberland, Eng. All the amorphous varieties of C are derived by natural or artificial incomplete combustion of the vegetable growth of the past or the present. Coal, for example, is the product of the changes effected in the forests of long ago by great pressure and terrestrial heat (due to changes in the earth's crust) with- out access of air, driving out more or less the liquids and gases of the trees and other plants from which the coal was formed. According to the relative completeness of carbonization, there are several kinds of coal. Anthracite, or "hard," coal contains hardly any volatile products; hence on burning it glows, but does not yield a flame. Bituminous, or "soft," coal, on the other hand, has not undergone so much pressure. It is rich in petro- leum (from which coal-oil is made) and in gaseous compounds; hence it burns with flame, or, if heated in suitable retorts in the absence of 0, the gases may be separated from the solid coal and be utilized as illuminating gas or for heating purposes. The residue of solid coal left in the retorts is termed gas-carbon or plumbagin. It is hard, compact, and difficult to fuse, and is much used for electrodes and battery-plates. Cannel-coal 130 INORGANIC CHEMISTRY. is a compact subvariety of bituminous, and was so named be- cause on combustion it gives a steady light like that of a candle. Lignite, brown, and wood coal, as the names indicate, are soft coals nearer to the woody nature of the coal-forming plants than is ordinary bituminous coal. It is most abundant in the Eocky Mountain regions. Jet is a peculiar kind of coal, so called because it is capable of taking a fine polish. Peat is a carbonaceous fuel made up of partly-carbonized vegetation mixed with mud. It is obtained in great quantities from the boggy districts of Ireland. Wood-charcoal (carbo ligni) is made from piles of wood (U. S. P., soft willow-twigs) by burning the latter with little air: that is, covered with earth. The wood consumed yields about Y B its weight of charcoal. Carbo ligni is a light, porous powder, noted for absorbing gases 90 volumes of NH 3 at ordi- nary temperatures, or about twice as much at f.p. Because of this property, wood-charcoal is much employed as a deodorizer to occlude H 2 S and other foul gases. It is also used internally for the same reason, in fermentive digestive disorders and as an antidote for poisons. The antiseptic power of charcoal is very slight. Wood-charcoal is employed as a fuel in metallurgy and in the manufacture of crucible and cementation steel. Experiment. Introduce a piece of heated charcoal into a test-tube previously filled with NH 3 over Hg, and note rise of the metal, owing to absorption of the gas. Animal charcoal (bone-black, ivory-black, carbo animalis) is prepared by the destructive distillation of bones in much the same manner as the ligneous variety is obtained. The crude product is purified by treating with dilute HC1, which dissolves out any Ca 3 (P0 4 ) 2 . Bone-charcoal is employed largely for decolorizing sugar and purifying petroleum, and also in boot-blacking and along with sand in water-filters. Carbonized blood is similar to bone-black, and is used for the same pur- poses. Coke is obtained from coal much in the same way as char- coal is from wood. It burns, of course, without flame, but furnishes a steady, intense heat. Lamp-black is the collected smoke of burning tar, rosin, turpentine, or petroleum, with a limited supply of air. It is identic with the soot of chimneys and lamp-chimneys, and has wide use in black paints and printers' and India ink. Certain woods, as pinon, are much richer in carbonaceous resins than others, and hence soon fill up a chimney with soot. Experiment. Burn camphor or turpentine in a wide-mouth bottle, and notice lamp-black formed. OXIDS. 131 Free C in any form is soluble only in molten cast-iron, forming a binary compound, called carbid, with the metal. A part, however, usually crystallizes out as graphite on cooling. C is fused and volatilized only by the electric arc light. It is not oxidized at ordinary temperatures, but at high ones has a great affinity for 0. Hence in the form of fuel it is much used as a reducing agent in smelting and as charcoal supports in assaying. C unites directly with very few elements, indirectly with a great many. In combination C is present in all plants and animals, in most combustibles, and in fats, oils, and car- bonates. C and H are the fuel-elements of the food. C in combination is readily shown by the substance charring on heating. Though the elements As and Sb are more closely allied to metalloids than to metals, they will be considered, for prac- tical convenience, with the latter groups. OXIDS. This class of compounds may be divided into neutral (water), basic, and acid oxids. Water, H 2 0, is the most abundant compound in Nature. It constitutes 65 or 70 per cent., by weight, of the human body, and is present in large amounts in both plants and animals, and also in most minerals as water of crystallization. Like air, it was thought to be an element until decomposed with electricity by Lavoisier in 1783. It occurs in Nature in three forms, being solid below 0, gaseous above 100 (at sea-level), and liquid between these temperatures. Experiment. Prove that dry wood contains H 2 by heating a match-stick in a glass tube sealed at one end. Water is composed of H and 0, 2 volumes of the former to 1 of the latter, the 3 volumes becoming condensed to 2; or, by weight, 8 parts of to 1 of H. The molecular weight of H 2 is 18; density of water-vapor, 9. Experiment. Decompose H 2 by electrolysis, and prove identity of gases. A little acid hastens the process. Water is produced in four ways: 1. By direct union of H and through the agency of electricity in a eudiometer or by burning H in air. 2. By oxidation or combustion of substances containing H. One to two pounds of H 2 is formed daily in the human body in this way. 3. By the action of an acid on 132 INORGANIC CHEMISTRY. a base or metallic oxid. 4. In the reduction of a metallic oxid byH. Pure H 2 is a colorless, tasteless, odorless, transparent, mobile liquid. In large quantities it appears blue or green. It is 773 times as heavy as air. The greatest density of water is at 4 C., at which point it is taken as the standard of specific gravity. Below this temperature, as well as above, it becomes lighter, expanding one-eleventh in changing to ice. It is the most universal solvent, and hence is never found absolutely pure unless distilled. It is a poor conductor of heat and elec- tricity, though better than air. The f.p. of H 2 is raised by anything, as rise in altitude, which diminishes pressure; and the same circumstances have the effect of lowering the b.p. Conversely, the b.p. under a pressure of 25 atmospheres is 224. The presence of salts in solution lowers the f.p. and raises the b.p. When water freezes it forms hexagonal crystals, best seen in the form of snow- flakes; slight agitation favors the process of congelation. When water vaporizes it expands to 1700 times the former volume; hence the power of steam. The great superiority of steam-sterilization over hot-air depends on the great amount of latent heat in steam. Water is a very stable compound, dissociation not taking place under 1000. It is neutral in reaction, and is therefore used very largely as a solvent for medicines and chemic re- agents. It unites, however, with metallic oxids to form bases or hydroxids, and with negative oxids to form acids, and is decomposed by a few of the most positive metals with evolution of H. Experiment. Show that CO 2 and H 2 O make an acid. Experiment. Show that CaO and H 2 make a base. Deliquescent substances, those which are very soluble in H 2 and take it from the air to be dissolved in, are used in the drying of gases and precipitates. Examples of such drying agents are CaCl 2 , H 2 S0 4 , and P 2 5 . The water of crystalliza- tion of minerals is held in place by a feeble chemic union (hydration) with the salt proper of the substance, and is readily separated by heating at 100 to 120, or, in the case of efflores- cent substances especially, by simple exposure to the air. Many medicinal mineral salts contain a large proportion of water of crystallization. Water is of more immediate necessity to the system than is solid food. It serves in the body to assist in processes of solution, secretion, excretion, circulation, and the regulation METALLIC, OR BASIC, OXIDS. 133 of heat by evaporation. Five or 6 pints daily should be taken by adults in food and drink. The official forms of water are as follows: Aqua is the Latin name for natural water. Aqua destillata is prepared by distilling 80 parts of pure natural water, the first 2 and the last 14 parts being rejected in order to prevent contamination, in the first place with gases, and at the end of the process with solid matters. The preparations called aquae are solutions in distilled H 2 of a gaseous or volatile substance. Those made from the volatile oils (peppermint, anise, etc.) contain 1 minim of the oil to each ounce of the solvent, solution being accom- plished with the aid of cotton. Liquors are aqueous solutions of fixed and solid bodies: e.g., liquor potassse, liquor calcis. Decoctions are aqueous solutions of vegetable substances, pre- pared by placing the given substance in boiling water for ten or fifteen minutes. Infusions are vegetable solutions made with water at a temperature below the b.p. By maceration in chem- istry is understood the continued action on a substance of H 2 at ordinary temperatures; when such extraction of medicinal agents is made with boiling H 2 0, the process is termed diges- tion. The separation of an alkali salt from its insoluble im- purities is called lixiviation; leaching ashes is a common ex- ample. METALLIC, OR BASIC, OXIDS. These are solid substances obtained by burning the metal in air or heating its hydroxid or carbonate. They are all in- soluble as such in water, but dissolve in acids without efferves- cence, forming salts. Oxids of the alkalies and alkaline earths combine with H 2 to form hydroxids, which are more or less soluble. Peroxids are ready oxidizing agents. Identification of Oxids. Mainly by negative reactions. No change when heated alone, except HgO (volatilizes and separates into elements) and AgO (leaves metal). After dissolving in an acid and removing metal with ELS or Na 2 CO 3 , no acid radical is found except that of solvent. Boiling or fusion with alkalies is also negative. Peroxids give off O when strongly heated, and evolve Cl when heated with HC1. Potassium. This metal has three oxids, the monoxid, K 2 0; peroxid, K0 2 ; and suboxid, K 4 0. The first is a white powder obtained by heating the metal in dry air. It becomes red hot when moistened with H 2 0. The second is a yellow mass obtained by heating the metal in excess of 0. When the 134 INORGANIC CHEMISTRY. metal is burned in insufficient air an unstable blue compound, K 4 0, is formed. Sodium. The monoxid, Na 2 0, is a gray mass combining violently with H 2 0. The peroxid, Na 2 2 , is a very caustic, light-yellow powder, used as an oxidizing and bleaching agent. On mixing with H 2 it yields about 20 per cent, of 0. Na 2 2 + H 2 = 2NaHO + Lithium. Li 9 is a white crystalline mass uniting with H 2 to form LiHO. Calcium. CaO (lime, quicklime, calx) is obtained by burn- ing limestone with alternate layers of fuel in a kiln. CaC0 = CaO C0 It is a gray-white, infusible solid, with a sharp, caustic, alkaline taste. It is a good drying agent, and is used in many industries. In the oxyhydrogen flame a stick of lime produces the intensely white Drummond, or calcium, light. On exposure to the air lime slakes: that is, becomes converted into a mixture of hydrate and carbonate by absorption of H 2 and C0 2 . Strontium. SrO is a gray-white powder used in sugar manufacture. Sr0 2 appears as a light, white powder. Barium. BaO is a light-gray, porous mass used in the manufacture of C. Ba0 2 is a light-gray or yellowish, coarse powder used for the preparation of H 2 2 . Magnesium. Magnesia, MgO, is prepared on a large scale by calcining at a red heat the carbonate, the light (calcined) or heavy (ponderosa) variety being formed according as the light or heavy carbonate is used. Compact magnesia is made by heating the nitrate or chlorid just to bright redness. MgO is a loose, white powder of an earthy taste. The official light magnesia is 3 1 / 2 times as bulky as the same weight of heavy magnesia. MgO is used as a face-powder, an antacid laxative, and an antidote for arsenic and corrosive acids. It is nearly insoluble in H 2 0, with which it forms the hydrate, which is dissolved by NH 4 C1 (used to separate Mg from Ca). A mixture of compact MgO, H 2 0, and chalk or marble-dust is used as a filling for decayed teeth. Zinc. ZnO is a white, floury powder much used in astrin- gent ointments and also in paints; it does not darken with H 2 S. It turns yellow on heating. It is used as a source of other Zn compounds. The purest ZnO is made by igniting the carbonate. Dental cements are made with dehydrated ZnO as a basis METALLIC, OR BASIC, OXIDS. 135 and a liquid. The cement commonly employed is Oxyphosphate, a solution of ZnO in pure glacial phosphoric acid. Oxychlorid cement consists chiefly of ZnO and a solution of ZnCl 2 (sp. gr., 1.5); Oxysulphate, of ZnO and ZnS0 4 in powder and ZnCl 2 so- lution, or solution of gum arabic and a little CaS0 3 . The powder and liquid are mixed thoroughly on glass or porcelain with a stiff spatula until a putty-like, elastic, non-adhesive mass is produced. Silica, borax, and ground glass are often added to make "set" mass harder and less contractile. The various shades of color, from light cream to dark yellow, are secured by proper manipulation of the heat in calcining the ZnO: dark yellow requires a white heat for two hours. Dental cements are broken up by either alkalies or acids. Oxyphosphate is the most durable cement. The oxychlorid is irritant, but some- what antiseptic, and is used for lining cavities prior to filling. Oxysulphate is non-irritant, but deficient in hardness, and is used for protecting pulps. All cements are more or less porous. Experiment. Oxyphosphate Cement. To prepare powder weigh out 45 gm. of crude ZnO, moisten with HN0 3 , and apply gentle heat, constantly stirring with glass rod until brown fumes cease. Then trans- fer powder to clean clay crucible and apply white heat in furnace for an hour or two. Remove from furnace, pulverize in mortar, sift through fine cloth, and bottle in three equal parts. To prepare liquid add a few pieces of glacial phosphoric acid to 10 or 15 c.c. of distilled H 2 in test- tube; heat gently from time to time, adding more acid till liquid is like glycerin in consistence; then filter and bottle. To make the cement pour liquid and solid near each other on mixing plate, adding the powder little by little to the liquid and spatulating until a homogeneous mass is obtained. Experiment. Oxychlorid Cement. To 10 gm. of calcined ZnO add and mix thoroughly 0.1 gm. of borax and 0.2 gm. of silica. Calcine in clay crucible in furnace at bright-red heat for a half -hour or more; then remove, pulverize, sift, and bottle. For the liquid portion dissolve granular Zn piece by piece in 10 c.c. of HC1, and heat gently till acid is saturated ; then filter through glass wool and preserve in well-stoppered bottle. The mixing process is the same as for Oxyphosphate. Experiment. Oxysulphate Cement. Mix 10 gm. of calcined ZnO with 4 gm. of dry ZnSO 4 . Place mixture in clay crucible and calcine in furnace as for oxychlorid; then pulverize, sift, and bottle. The liquid portion is obtained by dissolving 2 gm. of ZnCl 2 in 10 c.c. of H 2 O. In mixing the two portions the powder is added only until a cream-like mass is obtained. Copper. The cuprous compound, Cu 2 0, is a red powder, soluble in NH 4 HO. It is used to give a red color to glass. Cupric oxid, CuO, is an amorphous, dark-brown or yellow pow- der, soluble in NH 4 HO. In the presence of organic substances it gives up readily, and is much employed in organic analysis. It is also the coloring matter in artificial emeralds. CuO forms 136 INORGANIC CHEMISTRY. with H 3 P0 4 a hard and tenacious black mass sometimes used as a filling for teeth. Experiment. Heat in a hard tube a pinch of sugar with about ten times as much CuO until a coppery residue shows reduction. Mercury. Hg 2 is a dark-brown powder used in medicine as "black wash," made by the reaction between calomel and lime-water, 4 grains to the ounce. Hg 2 Cl 2 + Ca(HO) 2 = Hg 2 + CaCl 2 + H 2 HgO appears in two colors: rubrum and flavum. The red crystalline variety is prepared by dissolving Hg in three times as much 25-per-cent. HN~0 3 and evaporating; the resulting basic mercuric nitrate is rubbed thoroughly with 10 parts Hg to convert to the corresponding ous salt, from which HgO is sublimed. The yellow, amorphous oxid is prepared by reaction between HgCl 2 and NaHO. It is the chief ingredient of "yellow wash/' made by reaction between 25 grains of HgCl 2 and a pint of lime-water. HgCl 2 + Ca(HO) 2 = HgO + CaCl 2 + H 2 Both oxids are used extensively in medicine. Experiment. Make lotio nigra and lotio flava as above described. Aluminum. A1 2 3 , or alumina, is found native in hard crystalline minerals, and is made commercially from bauxite by the action of H 2 S0 4 or of Na 2 C0 3 . It is a light, white, odor- less, and tasteless powder, little acted on by acids or alkalies. Native oxids are very hard. Tin. SnO is a brown or white powder. Sn0 2 is a fine, white or buff powder, used as a polishing agent under the name of putty powder. Lead. The suboxid, Pb 2 0, is a soft, black powder. The official monoxid is in two varieties: massicot, prepared by heat- ing the carbonate or hydrate to low redness, and litharge, a by-product in desilvering lead-ores. Both are yellowish, but litharge is more inclined to red. They saponify fixed oils and fats. Litharge has extensive use in the manufacture of flint glass, in drying paints, glazing earthenware, and sweetening liquors, in lead plasters, and as the chief source of other Pb salts. The sesquioxid, Pb 2 3 , is also a reddish-yellow powder. Red lead, or minium, Pb 3 4 , is obtained by carefully heating (at 300) litharge. It is used as a pigment and in flint glass and cements. The peroxid or puce oxid is a chocolate-brown powder used as an oxidizer and left as a residue from red lead METALLIC, OR BASIC, OXIDS. 137 when this is heated with HN0 3 . Oxids of Pb are sometimes used to color artificial teeth. Experiment. Prove double composition of red lead by adding to a little in a test-tube 6 times its volume of dilute HN0 3 . PbO is dis- solved, leaving a dark-brown residue of PbO 2 . Bismuth. The only oxid of interest is Bi 2 3 , a yellow fusible powder,, prepared by roasting other salts of Bi. It is employed in making opera-glasses, for which purpose it sur- passes Pb. Chromium. Cr0 3 ("chromic acid") appears in brown-red needles, blackening temporarily on heating. On account of its great avidity for H 2 0, it is escharotic, and is used in 1-per- cent, solution as a hardening agent. It is an energetic labora- tory oxidizer, and hence should never be prescribed with oxidiz- able substances. Experiment. Pour absolute alcohol on a few crystals of Cr0 3 , or lay a crystal of CrO 3 on a pledget of cotton moistened with absolute alcohol. Spontaneous ignition takes place more rapidly when warmed. Experiment. Mix equal parts H,S0 4 and saturated solution of K a Cr 2 7 , and note red prisms of Cr0 3 separate as liquid cools. K 2 Cr 2 7 + H 2 S0 4 = K 2 S0 4 + H 2 Cr0 4 + CrO 3 Cr 2 3 (chromic oxid) is a dark-green powder used for col- oring glass, porcelain, enamels, and artificial teeth (modifies yellow of Ti0 2 ). Manganese. Mn0 2 , the. black oxid, is used in the labora- tory in the preparation of and Cl. It imparts an amethyst or purple color to glass and dental frit, and is utilized to re- move by oxidation the green color (due to iron-sand) of com- mon glass. It is the usual source of other Mn compounds, and unites with stronger bases to form manganates. Iron. Ferric oxid, Fe 2 3 , is obtained as a residue in dis- tilling fuming sulphuric acid from green vitriol. It is a dark- red powder used in paints, and as a polishing agent under the names jewelers' rouge, colcothar, and caput mortuum. Ferroso- ferric oxid, Fe 3 4 , is the natural black magnetite or lodestone, and is the chief constituent of "blacksmiths 7 scales/' Silver. Argentous oxid, Ag 4 0, is a black lustrous mass obtained by heating Ag 3 C 6 H 5 7 to 100 and at same time sub- jecting to H. Argentic oxid, Ag 2 0, is produced by reaction of hydroxids on AgN0 3 . It is a heavy, blackish, amorphous, slightly soluble, oxidizing powder. Highly explosive crystals of Berthollet's fulminating silver are produced by dissolving Ag 2 in strong NH 4 HO and diluting with H 2 0. The peroxid, Ag 9 6 2 , is even stronger as an oxidizer than Ag 2 0. 138 INORGANIC CHEMISTRY. Gold. Au 2 0, aurous oxid, is a dark-violet powder; Au 2 3 , auric oxid, a dark-brown powder. Au 2 3 and Pt0 2 lose their at low red heat. Miscellaneous. CoO and MO are both green powders. Os0 4 ("osmic acid") is a delicate histologic stain. Oxids of Ce, Th, and Zr are used for the mantle of Welsbach burners. NON-METALLIC OXIDS. These are gases, liquids,, or solids composed of united to some electronegative element. Many of them are termed anhydrids, since they join with water to form acids. Some of them, as As 2 3 , are improperly termed acids. Halogens. Three oxids of Cl are known: namely, mon- oxid, C1 2 0; trioxid, C1 2 3 ; and tetroxid, or peroxid, C1 2 4 . They are all heavy, greenish-yellow gases, with strong, irri- tating odors, and easily condensed to reddish liquids. In com- bination with H 2 the first and second form, respectively, hypo- chlorous and chlorous acids. On account of the slight affinity of for Cl, they are very unstable, and ignite or explode easily. Experiment. To Illustrate One Form of Spontaneous Combustion. To a little KC1O 3 in a beaker add a few drops of H 2 S0 4 . When the beaker is about filled with the greenish gas, drop into it a small piece of tissue-paper saturated with turpentine. No oxids of Br or F are known. The only oxid of I is the pentoxid, I 2 5 . This is a white, crystalline powder, very sol- uble in water, with which it forms iodic acid, HI0 3 . Sulphur. Four oxids are known; sesquioxid, S 2 3 ; dioxid, S0 2 ; trioxid, S0 3 ; and heptoxid, S 2 7 . The first and last are of no practical interest. S0 2 is formed whenever S is burned in air. One kg. of S produces 100 liters of S0 2 . It may be made pure by heating together S and H 2 S0 4 . S + 2H 2 S0 4 = 3S0 2 + 2H 2 Another laboratory method is to heat H 2 S0 4 with C or Cu. S0 2 forms a large percentage of volcanic vapors, and is abundant in the air of large cities from combustion of coal in stoves and furnaces. It is a colorless gas with a suffocating sulphurous odor, and is very hygroscopic, 40 volumes dissolving in 1 part of H 2 at 20. Experiment. Invert a dry tube filled with SO 2 over a vessel of H 2 O, and note rise of liquid in tube. It is neither combustible nor a supporter of combustion., NON-METALLIC OXIDS. 139 but reduces compounds actively. It bleaches straw, wool, and silk in the presence of water, by combining with the of H 2 0, leaving H free to unite with the of the organic coloring matter; the color may be restored by neutralizing with an alkali. Experiment. Place some fresh flowers on a tripod, and ignite a little S beneath, covering the whole with a bell-jar. The flowers are bleached, but may have their color restored by washing with a dilute alkali (removes S0 2 ) or with very dilute HNO 3 (restores O removed by 80,). As an anhydrid S0 2 decomposes NH 3 , ptomains, sulphids, and H 2 S, and kills bacteria. It is extensively used for fumigation of sick-rooms and in preserving meats. Aside from its odor, S0 ? is detected with paper saturated in solution of KI0 3 and starch, which turns blue, but is bleached by excess of gas. 2KI0 3 + 5S0 2 + 4H 2 = 2KHS0 4 + I 2 + 3H 2 SO 4 S0 3 is prepared most readily from fuming Nordhausen acid by application of heat, as follows: S0 3 appears in long, silky, transparent prisms, and is used in the manufacture of alizarin and for dissolving indigo. With H 2 it combines energetically to form H 2 S0 4 . Nitrogen. There are 5 oxids of N: namely, N 9 0, N 2 2 (NO), N 2 3 , N 2 4 (N0 2 ), and N 2 5 - All are unstable and easily dissociated by heat. They are formed in Nature by the passage of electricity through the atmosphere. N 2 (nitrous oxid, or laughing-gas) was discovered by Priestley in 1772. It is prepared by cautiously heating (be- tween 210 and 250) NH 4 N0 3 , which breaks up as follows: NH 4 N0 3 = N 2 + 2H 2 For anesthetic use N 2 should be purified of the higher oxids by passing the gas through two wash-bottles, one con- taining NaHO, the other FeS0 4 . N 2 is a colorless, odorless gas of sweet taste, soluble in about 1 volume of H 2 0. It is a decided disinfectant and a supporter of combustion, parting readily with its 0. It has received the name laughing-gas be- cause of the exhilarating effects it first evokes when inhaled. N 2 is much used by dentists as a pleasant and safe anesthetic for short operations. It is kept for convenience in the liquid state (30 atmospheres at 0) in wrought-iron cylinders, vapor- izing as soon as the pressure is removed. Experiment. Make N 2 O and note properties. 140 INORGANIC CHEMISTRY. Nitric oxid, 1ST 2 2 , is prepared by the reduction of HN0 3 with metals: Experiment. Pour HNO 3 on Cu, forming N 2 O 2 , a colorless gas, which in contact with the O of air becomes N 2 O 4 : an oxidizing agent characterized by red fumes. This is also a test for HN0 3 . 3Cu + 8HNO 3 = 3Cu (N0 3 ) 2 + N 2 O 2 -f- 4H 2 N 2 3 is a dark-blue liquid, made by warming HN0 3 with starch. It combines directly with H 2 to form HN0 2 . N 2 5 is a white, crystalline solid, obtained by treating dry AgN0 3 with Cl. It has a strong affinity for H 0, with which it forms HNO, Phosphorus. The oxids of P, P 2 3 and P 2 5 , respectively, are formed by the slow oxidation and by the rapid combustion of P. The former, a white amorphous powder with garlicky odor, unites with H 2 to form phosphorous acid, H 2 PH0 3 , the salts of which, termed phosphites, are of no medical interest. The white fumes of P 2 5 have an eager affinity for H 2 0, form- ing with it metaphosphoric, pyrophosphoric, or orthophosphoric acid, according as 1 molecule of the gas unites with 1, 2, or 3 molecules of H 2 0. Boron. B 2 3 is generally prepared by heating boric acid to redness: 2H 3 B0 3 = B 2 3 + 3H 2 It is a colorless, vitreous solid, and is used in blow-pipe work to convert nitrates, carbonates, and other salts into borates. Silicon. A grain of sand is, chemically speaking, silica, silex, or oxid of silicon, Si0 2 , of which there are three varie- ties (two crystalline, one amorphous) mentioned under ores. It is very abundant in rocks and soils, and is found in traces in all natural waters. Silica gives stiffness to stalks of grain and grass, and is present in the blood, hair, and bones of mam- mals. In the "petrified wood" found in Colorado and Arizona the C of former submerged forest-trees has been replaced by Si0 2 . Quartz is soluble only in HF. The other varieties of Si0 2 are also soluble in boiling solutions of alkaline hydroxids or carbonates. All forms of silica find extensive industrial uses, partic- ularly in the manufacture of glass, pottery, and artificial teeth. Agate is used for the hardest mortars. Kieselguhr, or diatom- aceous earth, is an amorphous form of Si0 2 used as an ab- sorbent for nitroglycerin in the production of dynamite. A NON-METALLIC OXIDS. 141 little sand sprinkled on the hot iron aids the process of welding by forming with the surface oxid a fusible slag. Experiment. Heat before blow-pipe a bead of microcosmic salt touched with a minute grain of sand, and note "silica skeleton" formed in bead. Carbon. Carbon monoxid, CO, is a colorless, almost odor- less, gaseous, unsaturated compound produced by incomplete combustion of C or carbonaceous substances in a deficient sup- ply of 0. It is formed in base-burner stoves at night, when but little air is allowed to enter the stove; also when there is a defective draught. The gas burns with a bluish flame, form- ing C0 2 . It is an active reducing agent, and diffuses readily through red-hot cast-iron: stoves and furnaces, for instance. Experiment. Make CO by heating together equal parts of wood- charcoal and CuO in a side-necked test-tube with delivery-tube, collect- ing gas over H,0. Experiment. Make CO by warming 1 part K 4 FeCy 8 with 9 parts of H 2 SO 4 . K 4 Fe(CN) 6 + GH 2 S0 4 + 6H 2 O = 2K 2 S0 4 + 3(NH 4 ) 2 SO 4 + FeSO 4 + 6CO C0 2 was the first gas to be separated from air, this event taking place in the seventeenth century. Pure country air contains 4 parts of C0 2 , by volume, in 10,000. The amount in the atmosphere is greatest at night. More than 7 parts in 10,000 are oppressive and injurious. This gas is also present in all natural waters, being most abundant in certain mineral springs; also in beer- and wine- vats; and is the "choke-damp" of wells and mines. It is produced by burning C with a free supply of air; also by respiration (expired air contains 4 to 5 per cent.), ordinary fermentation, and the oxidation and decay of organic matter. An ordinary lamp sets free in burning as much C0 2 as an adult person; a gas-jet two to four times as much. Artificially C0 2 is prepared by action of any common acid (mineral ones usually employed) on a carbonate. Experiment. Make CO 2 by treating Na 2 CO 3 with HC1, and test gas by passing into lime-water. Notice that the lime-water becomes at first cloudy, and then again when surcharged clear, owing to the formation of the more soluble acid carbonate of Ca. C0 2 is a colorless gas with a sharp taste and acid smell. It turns blue litmus purple or wine-red, the blue color being re- stored by heat. Although it is half again as heavy as air at the same temperature, the foulest air in a living-room is next the ceiling, because of the warming by the blood of the exhaled gas, and also since ventilation is usually less perfect at the top 142 INORGANIC CHEMISTRY. of the room. In wells and mines the gas is most abundant at and near the bottom. Experiment. Float soap-bubbles on C0 2 in a wide vessel. C0 2 is soluble in 1 volume H 2 with chemic union, form- ing H 2 C0 3 . The popular beverage known as soda-water con- tains 5 volumes of this gas to 1 of water. The gas is forced in under pressure, which is relieved for each glass of the liquid drawn, with consequent effervescence. C0 2 for soda-water is now sold liquefied by a pressure of 40 atmospheres in steel cylinders. On evaporation this liquid produces intense cold ( 110). Many mineral waters are artificially carbonated. The gas has been frozen into a snow-white solid. CO,, being an acid gas, has marked affinity for alkaline solutions. Experiment. Show absorption of C0 2 by alkaline hydroxids oy adding to test-tube or jar of gas a solution of KHO and shaking well, then remove stopper under water, and the latter rushes in to take the place of absorbed gas. C0 2 is neither combustible nor a supporter of combustion, and is used to some extent as the "chemic fire-extinguisher/' Experiment. Invert candle into jar of C0 2 . Experiment. Light candle again and place under bell-jar filled with air. When C0 2 amounts to 12 per cent, the light goes out. Hydrogen. Hydrogen peroxid, H 2 2 , is a colorless, syrupy liquid (sp. gr., 1.45), with a sharp odor and tingling, metallic taste. It is very soluble in ether and water. It is usually prepared as per the following equation: 3Ba0 2 + 2H 3 P0 4 = Ba 3 (P0 4 ) 2 + 3II 2 22 or more easily by passing C0 2 into aqueous suspension of Ba0 2 . Other acids may be used. It is concentrated by evaporating at not above 60. It corrodes metals and decomposes readily into H 2 and nascent or atomic 0, on exposure to air and sun- light, and especially when heated; hence it is a strong oxidizer, and should be kept in a cool place well stoppered. Experiment. Prove oxidizing action of H 2 2 : To a little HA solution add a drop each of K,CrO 4 and H 2 S0 4 and a little ether, and' shake. A blue color, due to perchromic acid, results. On account of its unstable character, H 2 2 should not be prescribed with any other substance than H 2 0. The ordinary NON-METALLIC OXIDS. 143 solutions of this compound vary in strength from 1 to 10 vol- umes of available 0, or up to 3 per cent., by weight, of pure dioxid. Boric acid, glycerin, and traces of free acids are of value as preservatives for these preparations. The peroxid is much employed for bleaching wool, teeth, and hair (combined with weak alkalies) and for cleansing (brightens old books and pictures) and antiseptic purposes. It is particularly useful in treating abscess cavities; the chemic action that ensues drives out the pus with effervescence. It also effervesces with blood, saliva, and other organic substances. Special Test. H 2 O 2 gives a blue color with a solution containing starch, KI, and FeSO 4 . 2KI + H 2 2 = 2KHO + I 2 Arsenic. As 2 3 (arsenous oxid, white arsenic) was known as early as the eighth century. It is the "arsenic bloom" of miners, and is obtained as a side-product in roasting ores con- taining As. The powder has a sweetish, disagreeable, metallic taste. It volatilizes at 218. Its solubility varies with the physic condition, the amorphous, glassy variety requiring but 30 parts of cold water, whereas the opaque, crystalline form is dissolved by not less than 80 parts. As 2 3 , though heavier than H 2 0, floats partly on this fluid, owing to repulsion. The solubility of either variety is greatly increased by the addition of a little HC1 or alkali. It is also soluble in 5 parts of glyc- erin. It is much used in medicine and dentistry; in embalm- ing, taxidermy, manufacture of green colors and opaque white glass; in calico-printing, and as the source of all As compounds. As 2 3 is used largely in dentistry as a devitalizing agent, usu- ally mixed with morphin or cocain and creasote, oil of cloves or phenol, sealed in with gutta-percha or other protective. It "kills the nerve" by causing such an irritant congestion of the pulp as to lead to strangulation of the vessels at the apex of the tooth. It is used by "cancer specialists" as an escharotic to "eat out" these tumors. Liquor acidi arseniosi is a 1-per- cent, solution of As 2 3 in water containing 5 per cent, of dilute HC1. As 2 5 (arsenic oxid) is of little medical interest; it is usually prepared by warming As 2 3 with HN~0 3 . Both this oxid and arsenic acid are used as oxidizing agents in the preparation of anilin colors. Antimony. The trioxid is a heavy, light-gray powder, in- soluble in HN0 3 , but readily dissolved by HC1, warm H 2 C 4 H 4 6 , or KHC 4 H 4 6 . It is used in preparing tartar emetic and as a substitute for white lead. 144 INORGANIC CHEMISTRY. INORGANIC ACIDS. These are strongly acid,, as a rule, and attack most metals, forming salts, with evolution of H. HYDRO-ACIDS. These are solutions of colorless, acid gases in H 2 0. They have a sharp, irritating odor. Their vapors redden moistened blue litmus-paper. They are generally prepared by treating the appropriate salt with H 2 S0 4 or H 3 P0 4 . They should leave no residue on evaporating to dryness. Their tests are, in gen- eral, the same as for their salts, but a few special ones are given below. HC1 is the most important of the hydro-acids. In the pure state it is a non-combustible gas one-fourth heavier than air. It is found naturally in the atmosphere, especially near vol- canoes and chemic works, and also in the human gastric juice (0.1 or 0.2 per cent.). HC1 is usually manufactured from com- mon salt by the chemic action thereon of H 2 S0 4 , with the aid of heat. 2NaCl + H 2 S0 4 = Na 2 S0 4 + 2HC1 Experiment. In a suitable flask place Va inch dry NaCl, fill flask 1 / s full with dilute H 2 S0 4 , heat till boiling hard, then pass gas into H.,0 in beaker. It may be purified Dy redistillation. On a large scale HC1 is a leading by-product in the manu- facture of soda. HC1 causes a red stain on dark cloths, readily removed by NTI 4 HO. HC1 gas is extremely soluble in H 2 0, 1 volume of the latter at dissolving 503 volumes, or 82 per cent., by weight, of the former. This solution has bleaching and antiseptic properties, and is much used as a reagent. Experiment. Show intense avidity of HC1 gas for H 2 O by opening a test-tube of the gas under water, tinged with blue litmus. Explain color-change and why the water rises in the tube. The official HC1 contains 32 per cent., by weight, of the gas, and has a sp. gr. of 1.16. The dilute acid is of 10-per-cent. strength; sp. gr., 1.05. The yellow color of common HC1 is due chiefly to Fe compounds. HC1 is used extensively in medi- cine, particularly when there is a deficiency of the acid in the gastric juice. In manufacturing chemistry it is employed in the preparation of chlorates, chloroform, and bleaching powder. Nitrohydrochloric acid (aqua regia) is made by mixing 40 INORGANIC ACIDS. 145 c.c. HN"0 3 with 180 c.c. HC1, letting them stand for a week or two. The reactions between the two acids are as follows: HN0 3 + 3HC1 = NOC1 + 2H 2 + 201 HN0 3 + 3H01 = NOC1 2 + 2H 2 + Cl It will be seen that HN0 3 oxidizes the H of both acids. The solvent power of aqua regia on Au and Pt depends on its free Cl and the chloronitrous and chloronitric gases, which give up their Cl very easily. The official dilute acid is made by diluting the strong acid with H 2 up to a liter. Special Test for HC1. Dense, white fumes (NH 4 C1) appear when a glass rod dipped in NH 4 HO is held over mouth of container. HBr can be prepared from any bromid (usually KBr) by treating it with concentrated H 2 S0 4 . The dilute HBr of the United States Pharmacopeia contains 10 per cent., by weight, of the absolute acid gas dissolved in distilled H 2 0, and has a sp. gr. of 1.077. Quinin is sometimes administered in dilute HBr, the Br of the acid neutralizing the hyperemic effect of the alkaloid on the inner ear. Special Test for HBr. Reddish fumes when heated with strong H 2 S0 4 . The official syrup of HI is of 1-per-cent. strength; the sugar serves to prevent actinic decomposition. HI readily parts with its H and is therefore an active reducing agent, being used in photography. Special Test for HI. Gas gives brown color to paper moistened with Cl water. The only important artificial compound of F is HF, pre- pared by gently heating in a leaden dish CaF 2 , treated with an excess of H 2 S0 4 . The HF gas thus formed combines with the silica of the glass, owing to which fact it has been used more than two hundred years for etching glass. Experiment. Show action of fresh HF on glass covered with a paraffin coating in which a design has been traced down to the glass. An aqueous solution of HF is used for marking thermom- eters and glass measures. It is very volatile and caustic, pro- ducing painful and slow-healing ulcers if allowed to come in contact with the skin. The local effect of the acid can be neu- tralized to some extent by applying NH 4 HO or some other weak base. The dilute acid is stored in gutta-percha bottles. H 2 S is a sweet-tasting, foul-smelling gas derived from the 10 146 INORGANIC CHEMISTRY. putrefaction of organic bodies containing S (eggs, for instance), and also present in many mineral waters. It is the chief con- stituent of sewer-gas, and burns in air with a blue flame. H 2 S is prepared for laboratory use by treating FeS with H 2 S0 4 (1 to 6). It rapidly decomposes on exposure to air into H and S, which accounts for the S deposits on the edges of sulphureted springs. This gas tarnishes silverware, and also combines with many other metals, giving precipitates with characteristic colors. Experiment. Show reaction of H 2 S on solutions of Pb, Sb, As, Sn, and Zn salts. Aside from the odor, we may detect very small quantities of the gas by saturating a piece of white filter-paper with lead acetate solution, and exposing it for some hours where we have reason to suspect the gas is escaping. The sulphids, or salts of H 2 S, constitute the most common ores of the more common metals. The black stools often noticed after taking Fe, Bi, or Pb salts are due simply to the union of the medicine with the H 2 S formed by putrefaction in the alimentary tract. Patho- logically H 2 S is present in fetid abscesses, and the odor of the gas in the urine in some cases aids to determine the rupture of an internal abscess into the urinary tract or a fistulous com- munication between the bladder and the rectum. Hydrofluosilicic acid, H 2 SiF 6 , is known only in solution. It dissolves metals, forming silicofluorids, which are pptd. by K salts as gelatinous K 2 SiF 6 . Chloric, perchloric, hypochlorous, hypobromous, bromlc, iodic, periodic, cyanic, thiocyanic, ferrocyanic, ferricyanic, man- ganic, permanganic, chromic, stannic, antimonic, and silicic acids have no practical interest. THIO-ACIDS. The most important and most powerful of the mineral acids is H 2 S0 4 , or sulphuric acid. It occurs free in the atmos- phere near chemic works and in volcanic springs and rivers (Andes). The principal sources of this acid are S and FeS 2 . The process of manufacture of H 2 S0 4 commonly depends on the oxidation of S0 2 into S0 3 in the presence of H 2 as steam. The intermediate agent in oxidation is N 2 4 , formed by treat- ing NaN0 3 with H 2 S0 4 . This gas, N 2 4 . gives up two atoms of to S0 2 , and is reduced to N 2 2 , which again takes up the from the air at hand, and so the reaction goes on indefinitely as long as the fumes of burning S or FeS 2 are passed into the chamber along with steam and air. INORGANIC ACIDS. 147 2S0 2 + N 2 4 '+ 2H 2 = 2H 2 S0 4 + N 2 2 The acid thus formed is purified by distilling, and is col- lected in leaden pans, concentration being completed in glass or Pt vessels. Experiment. Make H 2 S0 4 by carefully heating a little S and KC1O 3 in a test-tube till they ignite. Add H 2 O and test for acid as under "Sulphates." Fig. 26. Preparation of Sulphuric Acid. H 2 S0 4 is a colorless, odorless, oily, corrosive liquid of 96- per-cent. strength; sp. gr., 1.84. The official acid is 92 1 / 2 per cent.; sp. gr., 1.835. The aromatic sulphuric acid contains also alcohol and aromatics, and is of 20-per-cent. strength. H 2 S0 4 is intensely avid of H 2 0, and to this is due, in part, the characteristic effects of the acid on organic substances. Experiment. Show charring action of strong H 2 SO 4 on white sugar. On account of its hygroscopic properties, H 2 SO 4 is much em- ployed in desiccators. It combines with 2H 2 O to form H P ,SO 6 (orthosul- phuric acid), the reaction being attended by considerable heat and by 8-per-cent. reduction in volume. When mixed with H._,O the acid should be added gradually to the water, and not the water to the acid, as in 148 INOEGANIC CHEMISTRY. the latter event the acid steam that is thrown off may scald a person. Dilute H 2 SO 4 attacks metals more rapidly than the strong acid, since in the latter case the chemic action is soon hindered by the coating of sulphate that forms on the metal. The reddish-brown stain produced by this acid on dark textiles disappears on adding NH 4 HO. H 2 S0 4 is more extensively employed industrially than any other chemic compound. A million tons of the acid are con- sumed annually in England in the Leblanc soda-process. Other uses of this acid are in the manufacture of HN0 3 , of ether, nitroglycerin, gun-cotton, parchment-paper, and fertilizers, the production of C0 2 from marble-dust, the conversion of starch into glucose, the refining of petroleum, the separation of Ag and Au, drying of gases and precipitates, and in the dental laboratory the dilute acid is employed as a "pickle" for clean- ing metallic plates before and after soldering. Sulphurous acid, H 2 S0 3 , is formed by passing S0 2 into H 2 0, or by the reducing action of S or charcoal on H 2 S0 4 . Experiment. Make H 2 S0 3 by placing 10 or 20 gm. charcoal in a flask, covering with H 2 S0 4 and applying heat, passing gas through wash- bottle and collecting in water. Sulphurous acid is a colorless liquid; sp. gr., 1.035; of not less than 6.4-per-cent. strength, by weight, with an acid, sul- phurous taste and smell. It first reddens, then decolorizes, litmus; and is used to some extent as a bleaching and disin- fecting agent. Decolorization of an I solution with this acid depends on the conversion of I into HI as follows: H 2 S0 3 + I 2 + H 2 = H 2 S0 4 + 2HI Experiment. Show bleaching effect of H 2 S0 3 on permanganate solution. Both the acid and its salts are detected by giving a light- colored ppt. with Ag, Pb, or Hg, which blackens on heating, owing to the change of sulphite into sulphid. The fuming Nordhausen acid, H 2 S 2 7 , is a thick, oily liquid obtained by roasting basic pyrites (Fe 2 S 2 9 ) or by pass- ing SO, (from heated FeSOJ into H 2 S0 4 . This acid is a solvent for indigo. Hyposulphuric acid, H 2 S0 2 , is prepared by the reducing action of Zn on H 2 S0 3 . It is a yellow, unstable liquid; a pow- erful bleaching agent; and it ppts. the metals from solutions of their salts, as in the following reaction: HgCl 2 + H 2 S0 2 + H 2 = Hg + 2HC1 + H 2 S0 8 Experiment. Show reaction represented by above equation. INORGANIC ACIDS. 149 Among other sulphur acids of little importance may be mentioned H 2 S 2 3 (thiosulphuric), H 2 S 2 6 (dithionic), H 2 S 3 6 (trithionic), H 2 S 4 6 (tetrathionic), H 2 S 5 6 (pentathionic), and H 2 S 2 8 (persulphuric). H 2 S (hydrosulphuric acid) has been discussed already under "Hydro-acids." CARBONIC ACID. H 2 C0 3 is not known in a free state, since it splits up into C0 2 and H 2 as soon as formed. BORIC, OR BORACIC, ACID. H 3 B0 3 is obtained by evaporation from the steam-jets or fumeroles in the volcanic regions of Tuscany. In the United States it is also prepared by treating borax with HC1. The pure acid is a white powder, unctuous, odorless, and nearly tasteless. It is soluble in 26 water, 15 alcohol, and 10 glycerin. Special Tests. The solution in alcohol burns with a green-tinged flame. Dissolve in hot water and dip turmeric paper in solution. Color of paper unchanged, but on drying becomes brown-red, turning green on moistening with KHO. Boric acid is a valuable non-toxic and non-irritating anti- septic, which can be used with safety in any part of the body. It is often added to alkaloidal substances e.g., cocain to pre- vent decomposition. Boroglycerid is a thick, syrupy liquid, made by heating together 1 part of the acid with 1 1 / 2 parts of glycerin. It is an antiseptic depletant. H 3 B0 3 and boroglycerid are each used in combination with Na 2 S0 3 for bleaching discolored teeth. When heated to 100, H 3 B0 3 loses H 2 and becomes metaboric acid, HB0 2 , which on further heating (140) is con- verted into tetraboric acid, H 2 B 4 7 , of which borax is the principal salt. NITRO-ACIDS. True nitrous acid, HN0 2 , is a very unstable blue liquid, made by passing N 2 3 into ice-water, or by warming HN0 3 with starch-water. Nitric acid, HN0 3 , is generally prepared commercially by the action of H 2 S0 4 on KN"0 3 . The pure acid is a colorless, fuming, suffocative, and very corrosive liquid; sp. gr., 1.52 (U. S. P., 1.42); of 68-per-cent. strength. The dilute acid is of 10-per-cent. strength; sp. gr., 1.057. 150 INORGANIC CHEMISTRY. Experiment. Show corrosive action and yellow color (xantho- proteic test) of HN0 3 on black, woolen cloth. The same color is noticed on the nails, skin, or any nitrogenous substance. It parts easily with some of its 0, and is, hence, a strong oxidizing agent, for which reason it should never be prescribed with sugar, alcohol, glycerin, oils, or other combustible sub- stances. Experiment. Pour HNO 3 on warmed turpentine in beaker, and note spontaneous combustion. Most metals dissolve in strong HN0 3 , forming nitrates. Au, Pt, and Ir do not so dissolve, and Sb and Sn oxidize, but are not dissolved. These are dissolved by aqua regia, made by mixing together 4 HC1 and 1 HN"0 3 . Fe, Pb, and Ag dissolve in dilute, but not in strong, HN0 3 . When immersed in the latter a piece of Fe is rendered passive, not dissolving now in the dilute acid until some other metal, as Pt, is added to break the spell. The fuming acid is brownish red on account of containing in solution. HN0 3 on exposure to light and air decom- poses into a yellowish liquid, nitroso-nitric acid, which contains NO and is commercially known as nitrous acid. HN0 3 is used internally (diluted) and as a caustic; also in refining metals and engraving Cu plates, and in the manu- facture of gun-cotton, nitroglycerin, and anilin dyes. Test for Strong Acid. Red fumes of N 2 4 evolved on heating with Cu foil or filings. Green cupric nitrate is formed, H is evolved, and partly deoxidizes some of HN0 3 (HN0 3 + 3H = 2H 2 O + NO), forming NO (N 2 O 2 ), which takes up 2 from air and becomes colored. Test for Dilute Acid. Add some FeSO 4 to suspected liquid, and slide under mixture strong H 2 SO 4 . A brownish or black ring at point of contact proves presence of HNO 3 . PHOSPHORUS ACIDS. Orthophosphoric acid, H 3 P0 4 , is prepared by boiling P with dilute HN0 3 or by treating any phosphate with H 2 S0 4 . That used in dental cements is prepared by dissolving HP0 3 in warm water and evaporating to a syrupy consistence. The United States Pharmacopeia preparation is a colorless, odor- less, syrupy liquid containing at least 85 per cent, of absolute acid; sp. gr., 1.7. The dilute formula contains 10 per cent, of absolute acid. H 3 P0 4 is a tribasic acid, forming normal, acid, and double salts. It is not volatilized by red heat. Evaporat- ing spontaneously, it yields prismatic crystals. When H 3 P0 4 is heated to about 200 it loses water and is converted into pyrophosphoric acid, H 4 P 2 7 . INORGANIC ACIDS. 151 2H 3 P0 4 H 2 = H 4 P 2 7 When H 4 P 2 7 is heated nearly to redness, it is also dehydrated into glacial phosphoric or metaphosphoric acid, HP0 3 : a colorless, glassy solid. Both this acid and H 4 P 2 7 are corrosive and paralyzant poisons, acting especially on the innervation of the heart. Hypophosphorous acid, HPH 2 2 , is a white, crystalline substance, obtained by decomposing Ca(PH 2 2 ) 2 with oxalic acid. It is a strong deoxidizer. The dilute acid is of 10-per- cent, strength. On exposure to air it takes up and becomes the colorless liquid phosphorous acid, H 3 P0 3 . This, in turn, is oxidized into H 3 P0 4 . Differential Tests. H 3 PO 4 gives a yellow ppt. of Ag 3 P0 4 with argent-ammonium hydrate: soluble both in HN0 3 and NH 4 HO. Ortho- phosphoric acid gives a yellow ppt. with AgN0 3 ; meta- and pyro- white. Pyrophosphoric acid gives white ppt. with MgSO 4 ; metaphosphoric acid none at all. ARSENOTTS AND ARSENIC ACIDS. H 3 As0 3 is not known in the free state, but exists in solu- tions of As 2 3 . H 3 As0 4 appears in white, deliquescent crys- tals, which are strongly corrosive and blister the skin. Its solutions give a brick-red ppt. of Ag 3 As0 4 on adding argent- ammonium hydrate. HYDROXIDS. These may be regarded as H 2 in which one-half of its H is replaced by a metal. They are mostly white, crystalline, deliquescent solids (except NH 4 HO) with strongly alkaline re- action and caustic, alkaline taste. They are commonly purified by dissolving in alcohol and decanting. Commercial prepara- tions contain from 10 to 25 per cent. H 2 0. Hydroxids of the alkaline metals and alkaline earths are more or less soluble in H 2 0; all others insoluble. Solution produces considerable heat on account of taking up water of crystallization. The soluble hydroxids are recognized by melting and volatilizing unchanged, by dissolving in HC1 without odor or effervescence, and by giving a dark-brown ppt. of Ag 2 with AgN0 3 . The insoluble ones give off steam when heated in a nearly hori- zontal, dry test-tube, leaving a residue of oxid. KHO is soluble in 0.5 H,0 or 2 alcohol; the alcoholic so- lution soon turns dark yellow to brown, forming, in presence of air, aldehyd and acetic acid. Official liquor potassse is 5 per cent, in strength, with sp. gr. of 1.036. Potassa cum calce 152 INORGANIC CHEMISTRY. is a caustic paste composed of equal parts of KHO and CaO. Kobinson's remedy contains equal parts of KHO and carbolic acid. NaHO is soluble in 1.7 H 2 and is very soluble in alco- hol. Liquor sodas contains about 5 per cent. NaHO, and has a sp. gr. of 1.059. Crude NaHO has extensive use in soap- making. Ammonia, NH 3 is a gaseous compound present in the atmosphere in minute amounts in combination with nitrous, nitric,, and carbonic acids. It is a product of organic decom- position and dry distillation; soft coal yields about 2 per cent. Its chief source at present is the ammoniacal liquors formed during the manufacture of illuminating gas. The gas is freed from its compounds in this liquid by distilling with lime and collecting in water. NH 3 is colorless, and has a sharp, suf- focating smell. When mixed with it ignites, forming N", H 2 0, and HN0 3 . It is liquefied by freezing mixtures at 40 or by a pressure of 6 or 7 atmospheres. The liquid boils at 38.5, absorbing much heat; hence it is employed in cooling- apparatuses and in making ice. Water dissolves 600 volumes of the gas at ordinary temperatures, forming NH 4 HO. This hydroxid readily parts with its NH 3 , especially on warming, and hence is known as the volatile alkali. Experiment. With red litmus-paper moistened with H 2 and held in neck of bottle, show volatility of NH 4 HO, and notice that red color is restored on drying. NH 4 HO is official in two strengths: aqua ammonias (sp. gr., 0.960), containing 10 per cent., by weight, of NH 3 ; and aqua ammonias fortior (sp. gr., 0.901), of 28-per-cent. strength. Spiritus ammonias aromaticus is an alcoholic solution contain- ing 10 per cent., by weight, of the gas, and has a sp. gr. of 0.810. Ca(HO) 2 is a white powder slightly soluble in H 2 0, form- ing liquor calcis, or lime-water (0.15 per cent.). It is less sol- uble in boiling than in cold water. Glycerin or sugar renders it much more soluble: 8 grains per ounce. Lime-water is used extensively in medicine as an antacid remedy, and is an effect- ive chemic antidote in mineral-acid poisoning. Milk of lime is an aqueous mixture with more Ca(HO) 2 than will dissolve in the water. When Ca(HO) 2 is exposed to the air it changes to the carbonate by absorption of C0 2 ; hence the setting of mor- tar into plaster also due partly to the formation of a silicate with the sand. Ba(HO) 2 is obtained by treating BaO with H 2 0. It is soluble in 20 parts of H 2 0, forming the strongly alkaline test- INORGANIC ACIDS. 153 fluid known as baryta-water, which is clouded by the least trace of C0 2 . Mg (H0) 2 is very slightly soluble in H 2 0, with which it forms a gelatinous mixture ("milk of magnesia" 1 to 15 of H 2 0), but is freely soluble in solutions of NH 4 salts. Zn(HO) 2 is a white ppt. formed by the addition of KHO or NaHO to a solution of a zinc salt. It dissolves readily in excess of re- agent, forming a zincate. Au(HO) 3 , auric acid, is a yellow-brown ppt. prepared by heating a solution of AuCl 3 with magnesia and washing ppt. with dilute HN0 3 . When treated with excess of NH 4 HO an explosive brown or green pow r der, known as fulminating gold, is produced. Potassium aurate, KAu0 2 .3H 2 0, appears in small, soluble, yellow needles of alkaline reaction, used in gilding Cu. Cu(HO) 2 is a light-blue, bulky ppt., partly reduced to black CuO on boiling. When NH 4 HO is added to solutions of cupric salts a deep-blue color results, owing to the formation of ammonio-copper compounds [CuS0 4 (KE 3 ) 4 and others]. A1 2 (HO) 6 is an insoluble white powder much used as a mor- dant. Experiment. Show lake formed by adding Na 2 CO 3 and alum solu- tions to a cochineal solution. The acetate is commonly employed, the acetic acid being driven off by heat, leaving the hydrate. In the presence of more positive oxids A1 2 (HO) 6 may act as a weak base, forming aluminates. Lead oxyhydroxid [Pb(HO) 2 ,PbO] is readily soluble in ex- cess of precipitating caustic alkali, forming plumbates (K 2 Pb0 2 , ]S[a 2 Pb0 2 ), which on boiling throw down red or yellow lead oxid. Mn 2 (HO) 6 is a dark-brown substance obtained by at- mospheric oxidation of white Mn(HO) 2 , and is used in var- nishes. Fe 2 (HO) 6 is a reddish-brown gelatinous mass or magma, pptd. from ferric chlorid or sulphate by the addition of an alkaline hydrate. When dissolved in ferric chlorid or ferric acetate solution and then separated from the crystalloid sub- stances by dialysis, it is known as dialyzed iron. Both this and the ordinary freshly prepared hydrate are effective chemic antidotes for As. Fe 2 (HO) 6 gradually changes to oxyhydrate, Fe 2 0(HO) 4 . Experiment. By means of NH 4 HO ppt. hydroxids of Bi, Cd, Cr, Co, and Ni, and note color of each. Which are soluble in excess of reagent? THE PROPERTY OP HaboaiileiicalCillfipiftifiM! 154 INORGANIC CHEMISTRY. SALTS. HALOID SALTS. General Characters. Mostly white; saline, sharp, or bitter taste; neutral reaction; cubic crystals mostly; less often octa- hedra or rhombohedra; freely soluble in water (except Ag, Pb, and Hg 1 ), much less so in alcohol (deliquescent soluble); chiefly binary compounds; ternary salts unstable. CHLORIDS. These are usually formed by dissolving a metal or its hydrate or carbonate in HC1. Next to water NaCI (common salt) is the most abundant compound in Nature, being present in all natural waters and soils and to a slight degree in the atmosphere. It is a necessary ingredient of the fluids of ani- mals and plants, and is obtained chiefly from the salt-wells of New York and Michigan. A saturated solution contains 2.8 parts in 100 of water. A normal saline solution is of the same percentage as the blood, namely: 0.6 per cent., and is used by injection into the rectum, under the skin, or into a vein as a restorative measure in cases of hemorrhage, shock, or col- lapse. The chief sources of potassium compounds are sylvite (KC1) and carnallite (KCl,MgCl 2 .6H 2 0), mined at Stassfurt, Germany. NH 4 C1 is prepared by saturating the ammoniacal liquor from gas-works with HC1, evaporating to dryness, and subliming the residue as feathery crystals. It is used exten- sively as an expectorant and in calico-printing, dyeing, and soldering, and as a flux in refining gold. Experiment. To 10 c.c. NH 4 OH add HC1 until solution is neutral to test-paper, and evaporate to dryness on water-bath. What is the taste? How many c.c. of the acid should be required to saturate? CaCl 2 is very hygroscopic (soluble in 1.5 H 2 0), and the fused or anhydrous product is much used in drying gases and in the quantitative estimation of H in organic bodies. The hydrous compound CaCl 2 .6H 2 when mixed with powdered ice or snow makes an effective freezing-mixture. Its ready sol- ubility renders it of service for raising the b.p. of H 2 in the water-bath: a 50-per-cent. aqueous solution boils at 112. BaCl 2 is important mainly as the reagent for H 2 S0 4 and soluble sulphates, with which it forms the very insoluble BaS0 4 . MgCl 2 is found in sea-water and mineral waters and carnallite HALOID SALTS. 155 beds, and is a frequent impurity in table-salt. It is used in the manufacture of artificial stone and for finishing cotton goods in dye-works. ZnCl 2 is soluble in three-tenths of its own weight of water. It is very corrosive, even attacking cellulose, and is used as a caustic and in weak solutions as an antiseptic, astrin- gent, and deodorant; also by tinsmiths (flux for solder) and embalmers and to preserve wood. The official liquor contains 50 per cent, of the salt. Hg 2 Cl 2 , the mild chlorid, or calomel, is prepared by treat- ing any mercurous salt with HC1. It is a white, odorless, tasteless, and impalpable powder, insoluble in all ordinary solvents. Calomel volatilizes without first melting, and is the salt used for mercurial fumigation. It turns black on the addition of any hydrate, being changed thus to the correspond- ing oxid. The mild chlorid of mercury, in the presence of the free HC1 of the gastric juice, is apt to be transformed into the poisonous corrosive chlorid. This change can be prevented more or less by combining with the calomel NaHC0 3 to neu- tralize the acid of the stomach. The spontaneous decomposi- tion of HgoCL into HgCl 2 , that sometimes takes place on ex- posure to light or air, can be detected by pouring water over the powder and immersing in the fluid a bright strip of copper or other metal. If any of the mercuric salt is present in solu- tion, the metal will soon become tarnished. HgCl 2 (corrosive sublimate) is obtained by treating any other mercuric salt with HC1 or a chlorid. It appears in white crystals, which are odorless, but have a sharp, metallic taste and an acid reaction. On being triturated it remains pure white, whereas calomel turns of a yellowish tinge. HgCl 2 is soluble in 16 parts of cold water, 2 of boiling water, 3 of alco- hol, 4 of ether, and 14 of glycerin. The aqueous solution slowly decomposes in the light, reacting with the water as fol- lows: 2HgCl 2 + H 2 = Hg 2 Cl 2 + 2HC1 + The addition of a weak acid or of NaCI or NH 4 C1 serves to hinder this chemic change; these other chlorids also aid the solubility of the mercurial salt and make it less irritating. The bichlorid of Hg coagulates albumin (NH 4 C1 prevents), and is a popular antiseptic in the strength of from 1-10,000 to 1-1000. It should never be used to sterilize instruments, as it rapidly corrodes them, the metal uniting with one atom of Cl, calomel being deposited on the surface. The "white precipitate" pro- duced by treating HgCl 2 solution with NH 4 HO is used in oint- ments (official strength, 10 per cent.). 156 INORGANIC CHEMISTRY. Fe 2 Clg.l2H 2 is a yellowish-red, deliquescent salt prepared by dissolving the oxid in HC1. The official liquor contains 37.8 per cent, of the salt. The tincture is one-third the strength of the liquor, being diluted with 3 volumes of alco- hol, which reduces ferric chlorid to the ferrous state. The corrosive action of tincture of iron on the teeth is due to the presence of free HC1 in this preparation, and patients should be cautioned to rinse out the mouth after taking it through a glass tube. Experiment. Dissolve with heat 1 gm. of tine iron wire in 4 c.c. of HC1 and 2 c.c. of H,O. Filter, mix with one-third as much HC1, add slowly and gradually 10 m. HN0 3 , and evaporate till red vapors all escape. Mix with 4 c.c. hot water and set aside to form a solid mass of Fe 2 Cl 6 .12H 2 O. How much of this salt and how much FeCl 2 can be made from the gram of iron? AuCl 3 .2H 2 is a ruby-red crystalline compound forming double salts with HC1 and Nadl. AuCl 3 .NaCl is prepared by rubbing together equal parts of the dry salts. It appears in orange-yellow, deliquescent prisms used in medicine and den- tistry, in gilding, and as a toning agent in photography. PtCl 4 appears in soluble, reddish-yellow needles, obtained by dissolving Pt in aqua regia and evaporating the HN0 3 . It is used as a reagent for the quantitative estimation of K, NH 4 , and alkaloids. A1 2 C1 6 is used somewhat in weak solutions as a disin- fectant. SnCl 2 .2H 2 occurs as white needles. It is employed as a mordant in dyeing and calico-printing, and is also a strong reducing agent, precipitating As, Hg, and Au as metals from solutions of their salts. SnCl 4 is a colorless liquid forming crystals with one-third as much -water, and much used as a mordant for madder-red colors. A solution of SbCL, is used extensively for giving a bronze surface to iron and steel: gun- barrels, for instance. Identification of Chlorids. AgN0 3 in presence of HN0 3 gives a curdy, white ppt., insoluble in boiling HN0 3 , but instantly soluble in dilute NH 4 HO (1 to 20). CHLOEATES. KC10 3 and NaC10 3 occur as colorless, shining, monoclinic prisms with a cooling, saline taste. On heating they give off with deflagration. Violent explosions may result when rubbed with S or dry organic substances. Owing to their oxid- izing action, they are largely employed in calico-printing and the manufacture of anilin black. The K salt, soluble in 16 1 / 2 parts of H 2 0, is used as a detergent healing wash in disorders HALOID SALTS. 157 of the mouth and throat and in the manufacture of parlor- matches. Identification of Chlorates. Same reaction as chlorids after heat- ing solid to redness and dissolving residue in water, or after adding Zn and dilute H 2 SO 4 to solution. HYPOCHLORITES. Ca(C10) 2 is met with chiefly in chlorinated lime: a bleach- ing and disinfecting powder which contains also CaCl 2 and is prepared by passing Cl gas over slaked lime. NaCIO occurs only in solution as liquor sodae chloratas, which should contain 2.6 per cent, of available CL Its disinfectant action depends both on the Cl and the nascent 0. Hypochlorites liberate free Cl rapidly on addition of acids, and slowly, but spontaneously, on exposure to air, heat, and light through a reaction with C0 2 . Ca(C10) 2 .CaCl 2 + 2C0 2 = 2CaC0 3 + 2C1 2 Identification of Hypochlorites. Odor of Cl. Blue color with KI, starch paste, and acetic acid. PERCHLORATES. When KC10 3 is heated to 352 it is decomposed into KC10 4 , KC1, and 0. Further heating to 400 breaks up the perchlorate into KC1 and 0. KC10 4 is of no practical impor- tance. Like chlorates, it must be reduced to the chlorid before striking a ppt. with AgN0 3 . BROMIDS. These salts are usually made from Br by combining it with Fe or other metal and then decomposing w r ith a carbonate or hydrate. They have a pungent, saline taste, are very soluble (except Ag, Pb, and Hg 1 ) in both water and alcohol, and exert generally a sedative action on the nervous system. On heating they fuse and volatilize, with liberation of Br. They are also decomposed by sulphuric and nitric acids. The official salts are KBr, NaBr, NH 4 Br, LiBr, CaBr 2 , ZnBr 2 , and SrBr 2 . AgBr is used largely in photography. Identification of Bromids. AgNO 3 gives a dirty-white ppt., in- soluble in HNO 3 , slowly soluble in NH 4 HO, but insoluble in dilute (1 to 20) NH 4 HO. An aqueous solution, well shaken in a long tube with Cl water and a few drops of chloroform, yields a yellow-brown color, soon settling to a red stratum. 158 INORGANIC CHEMISTRY. HYPOBROMITES. These are analogous to the corresponding chlorin com- pounds. They are very unstable, and hence should be used fresh. They are decomposed by heat, leaving a bromid. NaBrO is a useful reducing agent in the estimation of urea in urine. BROMATES. These insoluble salts are of analytic interest only. KBr0 3 accompanies KBr as an additional product of KHO and Br 2 . It is reduced to bromid by heating with charcoal. If present in a bromid, a yellow color (Br) is produced on addition to the salt of dilute H 2 S0 4 . IODIDS. These salts are made directly from the element,, and con- stitute our most valuable alteratives. Being deliquescent, they are soluble in alcohol. KI is dissolved by 3 / 4 its own weight of water, 18 of alcohol, or 2 1 / 2 glycerin. Given largely diluted in water, it is a standard remedy for tertiary syphilis and in the treatment of chronic metallic poisoning. It appears to combine with these poisons accumulated in the tissues so as to render them soluble, and thus hasten their elimination. Nal is very similar to the K salt, but milder in action. Because of its volatile alkali, NH 4 I is of special service in chronic lung troubles. It is also the principal constituent of tincture of iodin decolorized with ammonia. The salts men- tioned appear in cubic crystals, but SrI 2 .6H 2 0, also official, occurs in hexagonal plates, and ZnI 2 in octahedra. The pearly, micaceous crystals of CdI 2 are used by photographers in iodized collodion. Agl is a heavy, amorphous, yellowish powder, sol- uble in an aqueous solution of KCN" or KI, and has consider- able use in photography. Hg 2 I 2 is a bright-yellow, insoluble powder, darkening to green on exposure to light, owing to decomposition into metal- lic Hg and HgI 2 . HgI 2 is a scarlet, amorphous powder (some- times octahedral), soluble in 130 alcohol, and almost insoluble in water unless KI is also present. It is extensively prescribed in the mixed treatment of syphilis, being formed here by reac- tion between KI and HgCl 2 . PbI 2 is a very slightly soluble, heavy, lemon-yellow powder used in ointments and plasters. It is distinguished from PbCr0 4 by being soluble in NH 4 C1 solu- tion on boiling. There are three iodids of As, of which AsI 3 is official. It appears in brilliant, orange scales, soluble in 7 parts of water NITRO-SALTS. 159 or 30 of alcohol. Liquor arseni et hydrargyri iodidi contains 1 per cent, each of this salt and HgI 2 . BiOI has been utilized to some extent as a substitute for iodoform. FeI 2 oxidizes so readily on exposure to air (becoming insoluble) as to require protection with about four times as much sugar of milk (ferri iodidum saccharatum). Syrupus ferri iodidi contains 10 per cent, of FeI 2 . The tasteless syrup is about half this strength, with citric acid, forming Fe 2 I 6 . Each fluidram of syrupus ferri et mangani iodidi has 6 grains of FeI 2 and 3 grains of MnI 2 . Identification of lodids. AgNO- gives a light-yellow ppt., insol- uble in both HNO 8 and NH 4 HO. Starch solution and a few drops of Cl water give a blue color; destroyed by excess of Cl. IODATES. The iodates, like the chlorates, are unstable compounds and ready oxidizers. They are of no practical interest. KI0 3 is formed along with KI when I 2 is added to KHO, and is reduced to iodid by heating with wood charcoal. To detect KI0 3 present as an impurity in KI add tartaric acid and starch paste, getting a blue color. The periodate may be prepared by passing Cl into a mixture of KI and KHO. FLUORIDS. CaF 2 , or fluorspar, is a common rock, used extensively as a flux in metallurgic operations. Cryolite, a double fluorid of Al and Na, is of importance as a source of metal Al, as is also A1 2 F 6 , formed by passing HF over heated alumina. Finely powdered fluorids warmed gently with a little H 2 S0 4 liberate HF, which etches glass, as described under the latter acid. NITRO-SALTS. General Characters. Unstable; explosive; ready oxidizers; anhydrous; white; neutral or nearly so; cooling, saline, pun- gent taste; soluble in water (except basic), not in alcohol; deflagrate on heating; refrigerants, diuretics, diaphoretics, and vasodilators. They occur in Nature commonly as an efflores- cence on walls or soils wherever organic matter is undergoing decomposition with evolution of NH 3 , which oxidizes under the influence of nitrifying ferments into HN0 2 and HN0 3 , and these unite with earthy and alkaline mineral matters. Arti- ficially they are made by dissolving a metal in ETN"0 3 . On heat- ing they evolve and N0 2 , leaving an oxid of the metal. 160 INORGANIC CHEMISTRY. NITRATES. KN"0 3 is used in medicine, fireworks, the refining of gold, and as a meat-preservative along with boric acid, borax, and Na 2 C0 3 . Ordinary gunpowder is 3 / 4 KN0 3 and about 1 / 8 each S and charcoal. The products of its combustion are CO, C0 2 , S0 2 , N, K 2 S, etc. NaN0 3 occurs naturally 'as an abundant de- posit in the dry regions of South America. It is very deliques- cent, and is used chiefly as a fertilizer; also as a meat preserva- tive and as a source of HN0 3 and KN0 3 . NH 4 N0 3 is utilized largely in the production of the mill anesthetic N 2 0. Ca(N0 3 ) 2 is a very deliquescent salt, soluble in both water and alcohol. Ba(N0 3 ) 2 is an essential ingredient of formulas for pale-green fires. Sr(N0 3 ) 2 is used in pyrotechnics because of the brilliant- red color it imparts to a flame. AgN0 3 is the most important medicinal salt of silver. It appears in colorless, transparent, tabular, rhombic crystals, sol- uble in 0.6 water or 26 alcohol. It is used chiefly for its cau- terant, styptic, or astringent effect upon diseased mucous mem- branes. In contact with animal matter AgN0 3 breaks up into metallic Ag, which stains, and free HN0 3 , to which the caustic properties are due. It is used further in hair-dyes, indelible inks, and photography. The fused-nitrate stick, or lunar caus- tic, contains a little AgCl to toughen it. The mitigated stick is made by melting together 1 part of AgN0 3 and 2 parts of JxJN U 3 . The nitrates of Hg are prepared by dissolving this metal in HN0 3 , the product being mercurous or mercuric according as the metal or the acid is in excess. Hg 2 (N0 3 ) 2 .2H 2 is of interest as being the only soluble mercurous salt; but in the presence of much water an insoluble basic compound is formed. Hg(N0 3 ) 2 is official in the liquor and the ointment. Pb(N0 3 ) 2 appears in large octahedra, soluble in 2 parts of water. It is used in the manufacture of mordants for dyeing and calico-printing. Cu(N0 3 ) 2 .3H 2 occurs in deep-blue, deli- quescent crystals that are highly corrosive. Bismuth subnitrate (BiO)N0 3 .H 2 0, is a heavy, white, tasteless, insoluble powder (mineral acids dissolve it readily). Like the subcarbonate, it is used for its local sedative effect; also as a cosmetic and in staining glass and glazing porcelain. Ferrous and ferric ni- trates are used in dyeing. Liquor ferri nitratis is a 6-per-cent. solution of Fe 2 (N0 3 ) 6 . Identification of Nitrates. Mixed with a solution of FeS0 4 in presence of H 2 SO 4 , a black coloration is produced, due to NO absorbed by ferrous salt, which is changed to ferric sulphate on heating, with disappearance of color. THIO-SALTS. 161 One drop of phenyl-sulplmric acid (1 part of carbolic acid, 4 parts of H,SO 4 , 2 parts of H 2 O) added to salt or residue evaporated over water-bath yields a reddish color, due to nitrophenol. NITRITES. KN0 2 and NaN0 2 are prepared by reducing the corre- sponding nitrates by heating with Pb or Cu. They are light yellowish in color, very soluble in water, and mostly soluble in alcohol, which is used to separate nitrites from nitrates. The Na salt is the essential constituent of spirit of nitrous ether, and is also employed in the manufacture of colors. Pb, Ag, and 4 nitrites are also known. Identification of Nitrites. Red fumes when treated with strong H 2 S0 4 . Dark-brown color with FeSO 4 without previous addition of H 2 S0 4 . Instant blue color with KI and starch paste on adding a few drops of HaSO*, which liberates nitrous acid. 2HNO 2 + 2HI = I 2 + 2H 2 + 2NO THIO-SALTS. General Characters. Usually white, and acid in reaction (hydrosulphids alkaline); give off sulphurous or sulphureted odors when heated or treated with mineral acids; mostly in- soluble, except the alkaline salts and a few others. Any com- pound containing S responds to hepar test, which is to fuse substance on charcoal with Na 2 C0 3 and KCN by means of blow- pipe. The sulphid thus formed, when placed on a silver coin and moistened with dilute HC1, causes a black stain of Ag 2 S. SULPHIDS. These are of little medical interest, though of extremely abundant occurrence in Nature. They are recognized by evolv- ing H 2 S when heated with HC1, the former acid being readily detected by its odor and characteristic reactions. A delicate test for soluble sulphids is the transient purple color produced by sodium nitroprussid. Sulphids insoluble in HC1 form sul- phates on heating with strong HN0 3 or nitrohydrochloric acid. Polysulphids K 2 S 3 , for instance are known by the deep- yellow or orange color of their solutions, and by evolving H 2 S with deposition of S on treating with HC1 or dilute H 2 S0 4 . CS 2 is a colorless, volatile liquid (sp. gr., 1.268) with an ethereal or fetid odor. It is prepared by passing vapors of S over red-hot coals. It is soluble in alcohol, ether, chloroform, 162 INORGANIC CHEMISTRY. and oils. The vapor is very inflammable, and acts as a depress- ant poison when inhaled. CS 2 is a powerful solvent of rubber and oils (used to extract seeds and animal refuse), S, P, and I. and an efficient insecticide. On account of its great refractive properties, it is used to fill the hollow glass prisms of the spec- troscope. Potassa sulphurata is a mixture of polysulphids with K 2 S0 4 and K 2 S 2 3 . Calx sulphurata is a crude CaS, and is phosphor- escent in the dark. HgS occurs as a black variety and two red ones, used in paints, namely: cinnabar, formed by sublimation of black HgS, and vermilion, made by subliming 8 parts S with 42 parts Hg. Vermilion is used to redden the rubbers for artificial dentures. SnS 2 is a gold-colored scale compound used for bronzing wood and gypsum. PbS is a black powder used for glazing pottery. As 2 S 2 is employed as a red coloring agent in leather manufacture and in the preparation of white or Indian fire (2 parts with 7 S and 24 KN0 3 ). Amorphous Sb 2 S 3 is used occasionally as an emetic and more frequently in vulcanizing caoutchouc, giving to this a reddish-brown color. FeS, obtained artificially by fusing together Fe and S, serves in the laboratory as the source of H 2 S. FeS 2 , the native pyrites, is of immense importance as the chief source of H 2 S0 4 and FeS0 4 . CdS is a yellow pigment used by artists. Ag 2 S (argentite, or vitreous silver) is found in Nature in dark-gray, regular crystals, and the so-called oxidized silver is ordinarily prepared by coating with a thin layer of Ag 2 S, obtained by heating together Ag and K 2 S. NH 4 SH, the sulphydrate or hydrosulphid, is obtained by saturating water of ammonia with H 2 S till a portion of the liquid ceases to cause a white ppt. with MgS0 4 solution. It is a colorless liquid, becoming yellow on exposure to the air, owing to formation of higher ammonium polysulphids and free S. The neutral compound (NH 4 ) 2 S is formed by adding excess (two-thirds more) of NH 4 HO. Both compounds are valuable reagents in analytic group work of the heavy metals. Ca(SH) 2 is known only in solution and is used as a depilatory. SULPHATES. The sulphates are bitter salts found in sea and salt-lake waters and many minerals. They are generally soluble in water (except Pb and alkaline earths), but insoluble in alcohol. They are used in medicine as hydragog cathartics and astringents. Na 2 S0 4 .10H 2 is employed in glass manufacture. (NH 4 ) 2 - S0 4 , prepared by saturating ammoniacal-gas liquor with H 2 S0 4 , and evaporating, is the basis for the manufacture of other NH 4 THIO-SALTS. 163 salts, and is a constituent of artificial manure. In addition to extensive medical employment, MgS0 4 is utilized as a finisher in dyeing and calico-printing. CaS0 4 .2H 2 0, or gypsum, is an abundant rock, which, when burnt at 115 so as to lose about three-fourths of its water and then ground, is known as plaster of Paris. This is a fine, white powder much used by artists (for casts), surgeons (for splints), and dentists (for molds) by reason of its "setting" with water, which is taken up as water of crystallization, forming the stone- like gypsum again. Borax, common salt, K 2 S0 4 , and other compounds quicken this process by facilitating osmosis. The K salt or alum and gelatin give a polished surface to the dry plaster. Under various trade-names plaster of Paris is used for giving a hard finish to plastered walls. Both hydrated and dehydrated gypsum are soluble in dilute acids and in syrup. Gypsum is also used as a fertilizer and cement, and the artificial salt (pearl-hardening, or annaline) is employed as a filling for writing paper. Experiment. Prove presence of water of crystallization in gypsum by heating a lump of this and noticing moisture on sides of tube and loss of crystalline appearance. BaS0 4 is a heavy, very insoluble compound used to give weight to cards and paper and as a pigment in water-colors, under the name of permanent white, since it does not blacken with atmospheric H 2 S. The sulphates of the heavy metals are generally astrin- gent, owing to the S0 4 radical being combined with not very positive metals. ZnS0 4 is an effective irritant emetic, and is used in finishing cotton goods. CuS0 4 .5H 2 occurs in large deep-blue, triclinic crystals, soluble in 2.6 parts of water, used as an astringent, as a mordant, in electrotyping, and in gravity batteries. CuS0 4 ,4NH 3 .H 2 0, made by adding excess of NH 4 HO to solution of CuS0 4 , is used as a styptic and as a test for As. The yellow subsulphate of mercury, Hg(HO) 2 S0 4 , is a nearly insoluble powder sometimes employed as an emetic. The alums are double sulphates comprising an alkaline and a sesquisulphate (Fe, Mn, Cr, Al) and 24 molecules of water of crystallization. Common, or potash, alum [K 2 A1 2 (S0 4 ) 4 .24- H 2 0] forms large, colorless, efflorescent octahedra having .a sweetish and strongly astringent taste and soluble in 10 1 / 2 parts of water. It is much used as a mordant in dyeing, calico- printing, and in the form of "lakes" for pigments. Experiment. Show insoluble lake formed by adding Na 2 CO 3 and saturated-alum solution to a cochineal solution", and note how the 1G4 INORGANIC CHEMISTRY. supernatant liquid is decolorized. The acetate is usually employed, the acetic acid being driven off by heat, leaving the hydrate. Alum loses all its water of crystallization (45 per cent.) on heating to 200, leaving dried, or burnt, alum, which is much less soluble than the hydrous salt, and is mildly escharotic be- cause of its avidity for water. Ammonia alum [A1 2 (NH 4 ) 2 - (S0 4 ) 4 .24H 2 0] has the same appearance and properties as potash alum and is somewhat more soluble. Al may be replaced by other metals, forming ferric alum [Fe 2 (NH 4 ) 2 (S0 4 ) 4 .24H 2 0], manganese alum, or chrome alum. Soda alum is much used as the acid element in cheap baking-powders. This practice is reprehensible, since a part of the salt changes in the stomach into phosphate and hydrate of Al, both of which are soluble in the gastric juice, and the continued use of such baking-powders leads to chronic dyspepsia and nervous disorders. Hot alum solutions make a good "pickle" for dissolving borax glass from metals after soldering. MnS0 4 .4H 2 appears in rose-colored crystals, soluble in an equal weight of water. It produces a permanent brown dye. FeS0 4 .7H 2 occurs as large, light-green, efflorescent crystals, soluble in water, but not in alcohol. It is found in Nature in ferruginous mineral waters. It is used for making ink and as a disinfectant. It destroys organic matters by abstracting their 0. Fe 2 (S0 4 ) 3 is a white mass dissolving in H 2 to make a reddish-brown solution of liquor ferri tersulphatis. This is styptic and hemostatic, like the subsulphate: Fe 4 0(S0 4 ) 5 . Identification of Sulphates. BaCl 2 produces a white ppt. of BaS0 4 , insoluble in boiling water (if reagent crystallizes out, this dissolves) and also in boiling HNO 3 . Insoluble sulphates (Ba, Sr, Ca, and Pb) must first be boiled with KHO or NaHO, or be ignited with an alkaline car- bonate and the blow-pipe on a piece of clean charcoal. SULPHITES. These are usually prepared by passing gas from burning S into solution of a hydrate, forming acid or normal salts, accord- ing to the relative amount of the reagents. They are unstable salts, gradually changing to sulphates on exposure to the air; act as reducing agents; and are decomposed by heat (some into oxids and S0 2 , others into sulphids and sulphates). The alka- line sulphates are soluble; all others insoluble. They are of very little use in medicine, though the sulphite of K and the sulphite and bisulphite of Na are official. NaHS0 3 is used in solid form and in solution as a preservative and a bleaching agent. This, like all sulphites, evolves S0 2 without deposition CARBON SALTS. 165 of S on heating with acids. CaS0 3 is used as a preservative by cider-makers, and the same salt in excess of H 2 S0 3 is employed by brewers. Benzoinated Na 2 S0 3 has been utilized by dentists as a deodorant. Identification of Sulphites. BaCl 2 , added to a neutral solution, gives white ppt. of BaSO 3 , soluble in dilute HC1. AgijSOg darkens on boiling, owing to decomposition into H 2 S0 4 and metallic Ag. THIOSULPHATES. Na 2 S 2 3 .5H 2 0, the commercial "hyposulphite," is soluble in two-thirds of its own weight of water, but insoluble in alco- hol. It is used extensively in photography, under the name of "hypo," to dissolve the unaltered halogen compounds of Ag. It is also employed to remove the excess of Cl in bleaching and paper-manufacture and in lixiviating silver-ores. Identification of Thiosulphates. Dilute or strong HC1 or H.,SO 4 drives off SO, and produces a yellow deposit of S. HYPOSULPHITES. NaHS0 2 , the true hyposulphite, is used in dyeing and to reduce indigo and in the estimation of free in the laboratory. The hyposulphite of Ag and Na is very soluble, and does not coagulate albumins nor stain the skin. CARBON SALTS. General Characters, Carbonates and bicarbonates are usually white and generally alkaline, because of the weak acid radical. Carbonates are generally insoluble, except alkaline; bicarbonates of alkalies and alkaline earths are soluble. Bicar- bonates are formed by passing excess of C0 2 into carbonate solution. Carbonates are generally prepared by passing CO, into solution of hydrate or by double decomposition of a soluble carbonate and soluble salt of the base. Both give off C0 2 on treating with acids, which dissolve them; the bicarbonates also on simple heating above 50. Bicarbonates tend to break down spontaneously into C0 2 , H 2 0, and carbonates, which, being less soluble, form sediments and deposits. CARBONATES AND BICARBONATES. K 2 C0 3 is derived from wood-ashes, fermented beet-roots, molasses, sheep's wool, carnallite, and kainite. It is soluble in a little more than its own weight of water, but insoluble in 166 INORGANIC CHEMISTRY. alcohol. Na 2 C0 8 .10H 2 is found in the ashes of all plants, espe- cially those growing near salt- water and in the Caspian and other seas. It is commonly man- ufactured in Europe from NaCl and H 2 S0 4 by the Leblanc proc- ess, the resulting sulphate or salt cake being reduced to sulphid with C in a revolving furnace, and at the same time caused to react with limestone. This crude soda, or black ash, is used in bleaching, soap-making, and the g manufacture of green glass. Pu- 3 rification is effected by lixiviation, I evaporating the concentrated so- 3 lution, and crystallization. The ammonia-soda process is preferred s in the United States. It consists ^ in running common salt solu- tion through NH 3 gas and then | through a saturated solution of C0 2 . The resulting sparingly 1 soluble NaHC0 3 is converted into a normal carbonate by heat. Na 2 - 2 C0 3 is soluble in 16 H 2 or 1 part glycerin, but is insoluble in alcohol. It is of great impor- tance as the base from which many other sodium salts are pre- pared. NaHC0 3 is employed in textile industries for its alkaline effect in scouring wool and un- gumming silk. It is a compo- nent of most baking-powders, be- ing combined in these with starch and some compound with an acid reaction, preferably KHC 4 H 4 6 . In presence of heat and moisture the two opposing salts react to liberate C0 2 , which raises the dough and renders the baked loaf light and porous. NaHC0 3 + KHC 4 H 4 6 = KNaC 4 H 4 6 + C0 2 + H 2 i!i!i CARBON SALTS. 167 The official ammonium carbonate is a compound acid am- monium carbonate with ammonium carbamate, and has the formula NH 4 HC0 3 .NH 4 NH 2 C0 2 . It appears in hard, striated masses, with ammoniacal odor and sharp, saline taste. When exposed to air it loses both NH 3 and C0 2 . A solution of the normal salt for reagent purposes is obtained by adding NH 4 HO (prevents absorption of C0 2 and formation of bicarbonate). Aromatic spirit of ammonia is a solution of normal carbonate in diluted alcohol, flavored with essential oils. Li 2 C0 3 requires 80 parts of water to dissolve it. It is used medicinally as a uric acid solvent. CaC0 3 is prescribed as an antacid, chiefly in the form of native chalk prepared by elutria- tion. Precipitated chalk is formed by the reaction between Na 2 C0 3 and CaCl 2 . It is non-crystalline, and is used in tooth- powders. Whiting and Paris white are impure forms of chalk used for polishing agents. Common putty is a mixture of whit- ing and linseed-oil. BaC0 3 and SrC0 3 are used as bases for the preparation of other salts. Magnesia alba [(MgC0 3 ) 4 Mg(OH) 2 .5H 2 0] is an official compound prepared by boiling each in 80 parts of water, 10 parts MgS0 4 , and 12 Na 2 C0 3 ; the solutions, mixed in the cold, are then boiled for fifteen minutes and strained. It is a loose, white, bulky mass, odorless, and of an earthy taste; practically insoluble in H 2 0, but dissolved readily by dilute acids, with active effervescence, giving off 761 volumes of C0 2 . It is also quite soluble in NH 4 C1 solutions. It is used as an antacid, and is cathartic in the presence of acids. The heavy carbonate of the British Pharmacopeia is prepared by mixing the above reagents each in 20 times as much H 2 and evaporating to dryness. The official zinc carbonate is an amorphous, impalpable, pale pink-brown powder of inconstant composition, which is usually expressed as 2ZnC0 3 .3Zn(OH) 2 . Almost totally insol- uble in water and alcohol, it dissolves readily in dilute acids, carbonated waters, and ammonium hydrate and carbonate. Ag 2 C0 3 differs from other carbonates in being yellow and turning black on exposure to air and light. Malachite and azurite, the native basic carbonates of Cu, are green and blue, respectively, and are used for ornamental purposes. Hg 2 C0 3 and basic mercuric carbonates are unimportant light-yellow and brownish-red salts. White lead, or basic lead carbonate [(PbC0 3 ) 2 Pb(OH) 2 ], manufactured from lead by exposing it to the simultaneous action of air, C0 2 , and vapors of acetic acid, is of immense industrial importance as the basis of most paints, for which 168 INORGANIC CHEMISTRY. purpose it is ground with 7 per cent, linseed-oil or turpentine and often variously colored. The basic bismuth carbonate [(BiO) 2 C0 3 .H 2 0] is a white powder used in medicine for its antacid and local sedative effect, being quite insoluble in water. Official FeC0 3 is protected from atmospheric oxidation by ad- mixture with sugar. Identification of Carbonates and Bicarbonates. They effervesce with any acid, except H 2 S and HCN, giving off a colorless, odorless gas which turns lime-water milky. Soluble carbonates give a white ppt. with cold solutions of MgSO 4 ; bicarbonates not. HgCl 2 gives a reddish- brown ppt. with carbonates of K, Na, and Li; a white ppt. with their bicarbonates. CARBIDS. The only carbid of interest is CaC 2 , lustrous, dark-brown, hard, brittle masses, prepared by heating in an electric furnace a mixture 'of lime and coal or coal-tar. It is important as being the source of acetylene-gas. STTLPHOCARBONATES. These salts resemble carbonates in constitution, but con- tain S in place of 0. PHOSPHO-SALTS. General Characters. Usually white; efflorescent; cooling, saline taste. Alkaline phosphates, phosphites, and pyrophos- phates soluble in water, but not alcohol; others soluble in dilute acids. Hypo-salts all soluble, unstable when in solution usually protected by sugar. They act chiefly as laxatives and mild biliary stimulants, except hypo-salts, which are used as a medium for the administration of P. PHOSPHATES, OR ORTHOPHOSPHATES. These are prepared by neutralizing (or a little more) H 3 P0 4 with a hydrate or carbonate. Three classes of salts are formed according as 1, 2, or 3 H atoms of the tribasic acid are replaced by the metal; 2 atoms are always replaced when the acid is neutralized by a carbonate. Trisodic phosphate, Na 3 P0 4 .12H 2 0, is alkaline in reaction. On exposure to air it absorbs C0 2 , form- ing Na 2 C0 3 and disodic phosphate. This latter, Na 2 HP0 4 .- 12H 2 0, is the official and commercial phosphate of sodium, and is the salt on which the alkalinity of the blood depends largely. It appears in large, monoclinic prisms, soluble in 5.8 H 2 0, but PHOSPHO-SALTS. 169 insoluble in alcohol. At a red heat it changes to the pyro- phosphate: 2Na 2 HP0 4 = Na 4 P 2 7 + H 2 Monosodic phosphate, NaH 2 P0 4 .H 2 0, has an acid reaction, and is the chief source of urinary acidity. Microcosmic salt, NaNH 4 HP0 4 .4H 2 0, on heating gives off water and NH 3 and forms a clear glass (sodium hexametaphosphate) on cooling. Hence it is used in blow-pipe analysis. Li 3 P0 4 is noteworthy as being the only insoluble Li salt. Ca 3 (P0 4 ) 2 occurs for the most part in the southern United States and West Indies in the phosphate rock made up largely of the bones of prehistoric marine animals. It is extracted with HC1 and precipitated with NH 4 HO. It dissolves readily in solu- tions of ammonium salts, NaN0 3 , NaCl, etc. It is prescribed in the syrup of calcium lactophosphate and is also used very extensively as a fertilizer. Acid phosphate or "superphosphate of lime" is a mixture of CaS0 4 and CaH 4 (P0 4 ) 2 , prepared by treating bones or phosphate rock with two-thirds as much, by weight, of H 2 S0 4 . It is employed in cheap baking-powders and as a fertilizer, being a necessary ingredient of seeds. Normal magnesium phosphate, Mg 3 (P0 4 ) 2 , is also found in bones. Ag a P0 4 is a pale-yellow, amorphous compound. Mn 2 (P0 4 ) 2 .2H 2 is a greenish-gray powder. Ferri phosphas solubilis is an official scale preparation containing Fe 2 (P0 4 ) 2 . Fe 3 (P0 4 ) 2 is a slate-colored compound turning blue in the air. It has been found in phthisic sputa, in pus, and in disinterred bones. Identification of Phosphates. BaCL gives white ppt., soluble in acetic and all stronger acids. Solution of (NH 4 ),MoO 4 in HN0 3 yields a yellow ppt., insoluble in HN0 3 , but soluble in NH 4 HO. AgN0 3 gives lemon-yellow ppt., soluble both in HNO 3 and NH 4 HO. PYROPHOSPHATES. As the name indicates, these salts are prepared by heat- ing orthophosphates to 250. There are two series, according as 2 or 4 H atoms of the acid are replaced. Na 4 P 2 7 .10H 2 is official, and occurs in colorless, transparent, monoclinic prisms or a crystalline powder. Fe 4 (P 2 7 ) 3 is the salt present in the official scale preparation ferri pyrophosphas solubilis. Identification of Pyrophosphates. AgN0 3 gives white ppt. in neu- tral solutions, soluble both in HX0 3 and in NH 4 HO. 170 INORGANIC CHEMISTRY. METAPHOSPHATES. These salts are prepared by heating the ortho-salts to red- ness. By polymerization five series of salts are formed, viz.: RP0 3 , metaphosphate; R 2 P 2 6 , dimetaphosphate; R 3 P 3 9 , K 4 P 4 12 ; and K 6 P 6 18 , hexametaphosphate. They are of no practical interest. They give the same reaction as that above under pyrophosphates, and, in addition, coagulate albumin. PHOSPHITES. They are strong reducing agents, and burn on Pt foil. The general formula of these salts is R 2 HP0 3 . They are of no consequence. They are distinguished from hypophosphites by yielding ppts. with Ba 'and Ca hydrates and with Pb(C 2 H 3 2 ) 2 . HYPOPHOSPHITES. These salts are prepared from the Ca or Ba salt by double decomposition with a carbonate. The hypophosphites are active reducing agents, and should not be rubbed with oxidizing agents for fear of an explosion. When heated in a dry test-tube they give off H 3 P, which ignites spontaneously with a yellow, phos- phorescent flame. Experiment. Boil together in solution any hypophosphite and HgCl 2 , and note ppt., first, of white calomel and then black mercury. KH 2 PO 2 is soluble in 0.6 water and in 7.3 alcohol; NaPH 2 O 2 .H 2 O in 1 water or 30 alcohol; Ca(H 2 P0 2 ) 2 in 6.8 water, not in alcohol; Fe 2 (PH 2 2 ) 8 sparingly in water, not at all in alcohol. The official syrup contains the first three salts just mentioned. Identification of Hypophosphites. (NH 4 ) 2 MoO 4 gives a fine, blue ppt. PHOSPHIDS. The only phosphid of any importance is Zn 3 P 2 . It is made by direct union of P and melted Zn, and appears as a gritty, dark-gray powder or minutely-crystalline, friable fragments with metallic luster. It is insoluble in water or alcohol, but dissolves in HC1, with evolution of H 3 P. It is a convenient medium for administration of P. BORATES. Orthoborates, from H 3 B0 3 , are very unstable. The meta- borates, from HB0 2 , are more stable, but of no practical con- sequence. The pyroborates are very stable. The most impor- ARSENITES AND ARSENATES. 171 tant pyroborate is borax, Na 2 B 4 7 .10H 2 0, which is obtained as a sediment from the borax lakes of Persia, Thibet, California (Death Lake), and Nevada (Pyramid Lake). It is a white, pris- matic, crystalline, feebly alkaline substance, soluble in 16 parts of water and less than 2 of glycerin; it is insoluble in alcohol. On heating sufficiently borax swells up and loses its water of crystallization, fusing into a glass-like body. Borax beads pre- pared in this way have a great affinity for oxids, and with the blow-pipe give characteristic colors in the oxidizing and reduc- ing flames for certain metals. This avidity of borax for oxids explains its use as a cleansing agent in the processes of welding, brazing, and soldering, and as a flux in refining. It is also employed as a preservative and in the manufacture of certain kinds of glass, soap, and enamels. Glycerin or mineral acids liberate H 3 B0 3 from borax. Na 2 B 4 7 .10H 2 + 2C 3 H 5 (HO) 3 = 2C 3 H 5 B0 + 3H 2 + 10H 2 C 3 H 5 B0 3 + 3H 2 = H 3 B0 3 + C 3 H 5 (HO) 3 Identification of Borates. CaCl 2 , rendered slightly alkaline with H 3 , on heating gives white ppt., soluble in HC 2 H 3 O 2 . On rendering solution just acid with HC1, turmeric paper dipped in it turns brownish red on drying, changing to green on moistening with KHO. ARSENITES AND ARSENATES. These are very poisonous salts. All but the alkaline are insoluble. The most important is K 3 As0 3 , of which liquor potassii arsenitis is a 1-per-cent. alkaline solution flavored with compound tincture of lavender. Sodium arsenite and arsenate are used for cleansing in calico-printing. Scheele's green, CuHAs0 3 , is a common green pigment. Paris green, well known as a pigment and insecticide, has the formula Cu(C 2 H 3 2 ) 2 ,- 3Cu(As0 3 ) 2 . Of the arsenates, Na 2 HAs0 4 .7H 2 is used in medicine, liquor sodii arsenatis being a 1-per-cent. solution. It is soluble in 4 parts water and very sparingly in alcohol. On fusing ar- senic with alkaline carbonates pyro-arsenates, analogous to pyrophosphates, are formed. Identification of Arsenites. Yellow ppt. with AgN0 3 or with H 2 S in presence of HC1; green ppt. with CuSO 4 . Usual tests for As. Identification of Arsenates. React same as phosphates, except that arsenates give a brick-red ppt., instead of yellow, with AgNO 3 . Insoluble arsenates should be boiled with NaHO, filtered, and the nitrate exactly neutralized with dilute HN0 3 before testing with AgN0 8 . 172 INORGANIC CHEMISTRY. ANTIMONATES. The acid pyro-antimonate of Na (Na 2 H 2 Sb 2 7 .6H 2 0) is noteworthy as being the only insoluble compound of this metal. Potassium metantimonate (2KSb0 3 .5H 2 0) is a gummy or crystalline mass prepared by deflagrating Sb and KN0 3 , boil- ing with water, and allowing to evaporate. Identification of Antimonates. Strong HC1 throws down white ppt. of HSb0 3 . (See also tests for Sb.) CHROMATES. These salts are all characterized by being colored yellow, red, or orange. Chromates of the alkalies are soluble; other chromates generally insoluble. They are irritant poisons. K 2 Cr0 4 occurs in yellow, rhombic, weakly alkaline crystals, soluble in 2 parts water. On adding acids its solutions turn red, owing to the formation of the dichromate, K 2 Cr 2 7 . This salt is soluble in 10 water, the solution being acid. It is an oxidiz- ing agent (with H 2 S0 4 ) used extensively in dyeing and tanning and in photography. It is the source of the other Or com- pounds. !N"a 2 O0 4 and Na 2 O 2 7 are similar to the K salts, but are more soluble. PbCr0 4 is much used in paints under the name of chrome-yellow. Chrome-red is a basic lead chromate, PbCr0 4 ,Pb(HO) 2 . BaCr0 4 is also employed as a pigment under the name of yellow ultramarine. The soluble chromates pre- cipitate Ba, but not Ca, from solutions. Identification of Chromates. Pb(C 2 H 3 2 ) 2 or BaCl 2 give a yellow ppt., soluble in HNO 3 , but not in HC 2 H 3 O 2 ; KHO darkens (green) and dissolves the lead salt. Treated with excess of H 2 SO 4 and shaken up with ozonized ether, a brilliant-blue color appears. Acids turn chromate solutions orange; alkalies turn dichromates yellow. MANGANATES. These are unstable oxidizing compounds, only the alkali salts dissolving in H 2 0, forming green solutions. K 2 Mn0 4 so- lution on standing (quickly on boiling) changes to perman- ganate, its color at the same time passing from dark green through blue and violet to red. 3K 2 Mn0 4 + 2H 2 =K 2 Mn 2 8 + 4KHO + Mn0 2 Experiment. Heat strongly in a casserole equal parts of MnO 2 , KHO, and KC1O 3 . Let cool and then dissolve out green K 2 MnO 4 with water. Pour this solution into more water, and note that it becomes violet (K 2 Mn a 8 ), with ppt. of Mn,(HO) 6 . SILICATES. 173 K 2 Mn 2 8 appears in dark-purple, metallic, lustrous prisms, soluble in 16 H 2 0. It is a powerful oxidizing agent, deodorant, antiseptic, and disinfectant: in neutral solutions giving off 3 atoms of 0; in acid solutions 5 atoms. A common method of sterilizing the hands is to wash them first in K 2 Mn 2 8 solution and then remove this stain with oxalic acid, followed by alco- hol. The other permanganates are similar to the K compound. Asbestos-paper should be used in filtering solutions of man- ganates or permanganates. Experiment. Add a few drops of absolute alcohol to powdered K:,Mn.,0 8 . Ignition takes place. identification of Manganates. Dilute acids change to perman- ganates with the gamut of colors above mentioned. Identification of Permanganates. Purple-red solutions, entirely decolorized by H 2 C 2 O 4 . Evolves Cl on mixing with HC1. STANNATES. Stannic and metastannic acids dissolve in alkalies to form salts known as stannates and metastannates. The most impor- tant compound is sodium stannate, or "preparing salts," Na 2 - Sn0 3 .4H 2 0, used largely as a mordant in dyeing and calico- printing. The alkaline metastannates, K 2 H 8 Sn 5 15 , are also used in dyeing. Identification of Stannates. HC1 ppts. white gelatinous H 2 SN0 3 . (See tests for tin.) ZINCATES AND ALUMINATES. These soluble salts are formed when Zn or Al is dissolved in an alkaline hydrate. Their respective radicals are (Zn0 ) n and (Al 2 4 ) n . TTTNGSTATES. Sodium tungstate, ]STa 2 W0 4 , is used in making fire-proof fabrics. SILICATES. Although forming the great mass of the earth's crust, the silicates are not much employed in medicine. Felspars are fusible silicates of Al and K or Na. These rocks break down into clays, ordinarily colored with Fe (ocher), mixed with CaC0 3 (marl) or organic detritus (loam). Kaolin, or china clay, is the purest native Al silicate, and has the approximate composition Al 4 (Si0 4 ) 3 .4H 2 0. Topaz is fluoro-aluminum silicate; turquoise, A1 4 (P0 4 ) 2 (HO) 6 .2H 2 0. The precious green stone beryl is a silicate of Al and Be. 174 INORGANIC CHEMISTRY. The best-known artificial silicate is Na 2 Si0 3 , or soluble glass, liquor sodii silicatis, which is prepared by fusing sand with excess of Na 2 C0 3 and running the melted mass into water. It is used for surgical bandages. K 2 Si0 3 is also soluble. Fuller's earth is a smooth earth useful as a skin dressing for infants. Glass is a silicate of various metals. Bohemian, or hard, glass is made by heating together in proper proportions lime, sand, and K 2 C0 3 . It is difficult to fuse, and resists the cor- rosive action of chemicals; hence is used extensively for labora- tory utensils. Crown, or soft window-, glass is a Na and Ca silicate, with addition of a little Fe and Al. Bottle glass con- tains more Fe and Ca and less K. Flint, or crystal, glass is a silicate of K and Pb; it is readily fusible, lustrous, and highly refractive to light, on which account it is chosen for making lenses and other optic apparatus. The color of colored glass depends on a small quantity of some metallic oxid: Co gives blue; Mn, amethyst; ferrous, bottle-green; ferric, brownish yellow or black; Cr, greenish yellow; cuprous, ruby; cupric, bluish green. Oxids of Zn and Sn and Ca 2 (P0 4 ) 2 give a white opacity to glass. Porcelain is made from a paste of water and kaolin, to which some silica (silex) is added to prevent cracking on dry- ing, and also felspar to act as a flux and vitrifying cement. The unglazed fired or kiln-burnt product is then dipped into a thin cream of the glaze (same as body, with excess of felspar to render very fusible), dried, and burned again at a white heat. The porcelain is colored, if desired, with metallic oxids, cobalt- blue, chrome-green, etc. Dental porcelain for artificial teeth contains a relatively large percentage of felspar, so as to render them more trans- lucent and life-like. The different enamel shades are secured by the use of purple of Cassius, spongy Pt, oxid of Ti (rutile- yellow), or gold and CoO (blue points); for dental uses the silex and felspar are heated to white heat, plunged into cold water, and ground fine. Kaolin is purified by twice washing, letting settle, and decanting, then drying in the sun. The dry method of preparing enamel has three steps: 1. Preparing metallic oxid by fusing tin, silver, and gold with borax; removing borax glass; dissolving the silver in H]ST0 3 ; washing and drying residue. 2. Fritting, or uniting this powder by heat with a flux of quartz, borax glass, and Na 2 C0 3 . 3. Diluting frit with sufficient felspar to secure desired shade. Stoneware is a coarse porcelain made from clays contain- ing Fe 2 3 and a little CaO to render somewhat fusible. Glazing may be accomplished simply by throwing into the furnace NaCl, SILICATES. 175 which forms a fusible silicate of Na over the surface of the vessels. The finest earthenware is prepared from white clay mixed with considerable Si0 2 by drying, tiring, and dipping into a readily fusible glaze mixture, which often contains PbO; then drying and refiring. Colored designs are printed on paper with oil and enamel pigment and then transferred to the ware before glazing. The oxids of Pb and Sn yield a whitish, opaque glaze, which may be attacked by acids and lead to poisoning. Kaolin contains about 40 per cent. A1 2 3 and 46 per cent. Fig. 28. Interior of Pottery Kiln. Si0 2 ; the fusible clays used for common earthenware are two- thirds Si0 2 and one-fourth A1 2 3 ; fire clays contain a large proportion of Si0 2 ; brick-maker's clay is about one-half Si0 2 and one-third A1 2 3 . Clays are "acid" or "basic" according to the relative amount of Si0 2 and A1 2 3 . The change caused by heating, from plastic to hard and porous, is due to expulsion of the combined H 2 0. Cements, or hydraulic mortars, are basic silicates of lime and alumina made by burning calcareous clays or cement-rock or suitable artificial mixtures. They 176 INORGANIC CHEMISTRY. plaster of Paris: by taking up water into combination. Com- mon, or Koman, cements are derived from clay or rock burnt below the sintering-point. Portland cement is such a mixture of limestone and clay or rock as will yield, on burning till sintered, a product containing 55 to 60 per cent, of CaO, 22 to 25 per cent, of Si0 2 , and 7 per cent, of A1 2 3 . Ultramarine is a blue coloring matter consisting of sili- cates of Na and Al with Na 2 S. It is made by heating to red- ness in fire-clay crucibles a mixture of kaolin, charcoal, and sodium sulphate or carbonate. The resulting green mass is roasted with S till the required shade of blue is obtained. The color is destroyed by heating with HC1, H 2 S being evolved. When dry gaseous HC1 and air are passed over common ultra- marine at 100-150, its color is changed to red or violet. Asbestos, or amianth, is a fibrous silicate of Ca and Mg. It is infusible and a poor conductor of heat. It is used for household utensils, as a fireproof lining material in buildings, and as a non-conducting packing for steam-apparatus and boilers. Identification of Silicates. On adding HC1 or NH 4 C1 to a soluble silicate, nearly transparent gelatinous H 4 SiO 4 is precipitated. On drying and heating to 150 and dissolving away chlorids with dilute HC1, Si0 2 is left as a gritty, white powder. Insoluble silicates are first rendered soluble by fusing with 5 parts of mixed K and Na carbonates. A bead of microcosmic salt (NaNH 4 HPO 4 ) touched with the pow- dered silica or silicate becomes opaque and shows within a floating mass called the "silica skeleton." ORGANIC ACID SALTS. General Characters. Generally soluble, except oxalates; many have characteristic odors, especially on heating or treat- ing with mineral acids; char when heated on Pt (except for- mates; oxalates turn a little gray) and leave residue of carbonate or oxid; changed mostly to carbonates in blood, rendering this more alkaline and urine less acid. OXALATES. These salts have an intensely sour taste. The alkaline oxalates are the only soluble ones (BaC 2 4 slightly soluble), the NH 4 salt being used as a reagent for Ca solutions. Ce 2 - (C 4 ) 3 9H 2 is a white, granular, tasteless powder, insoluble except in mineral acids. At red heat it leaves a yellow or salmon mixture of oxids. CaC 2 4 is often found in urinary sedi- ments and may give rise to concretions. K 2 Fe(C 2 4 ) 2 is a ORGANIC ACID SALTS. 177 strong reducer, and is used as a developing solution in photog- raphy. KHC 2 4 , like the acid, is very poisonous. It is used somewhat to bleach straw and remove ink-stains. Identification of Oxalates. Cad, in neutral or alkaline solution gives white ppt. of CaC 2 O 4 , insoluble in acetic, but soluble in hydro- chloric, acid. Dry insoluble oxalates heated in a test-tube evolve inflammable CO and leave a carbonate (effervesces with acids). ACETATES. These are made by neutralizing carbonates or hydrates with HC 2 H 3 2 . Neutral acetates are all soluble freely in water and less so in alcohol; basic acetates are insoluble unless a little HC 2 H 3 2 is added to form a neutral acetate. Official are the acetates of K, Na, Zn, and Pb; also in the liquors of NH 4 , Fe and NH 4 (red), and lead subacetate, Pb(C 2 H 3 2 ) 2 .PbO. This last is an effective sedative astringent. The others have gen- erally a diuretic, refrigerant, and alkaline action. Lead-water, liquor plumbi subacetatis dil., is a soothing lotion made with 4 dr. liquor plumbi subac. in a pint of distilled water. Both these absorb C0 2 on exposure and become milky. A1 2 (C 2 H 3 2 ) 6 and Fe 2 (C 2 H 3 2 ) 4 are used as mordants in dyeing under the names "red liquor" and "iron liquor." The former is also employed by dentists as a disinfectant and deodorant. The basic acetate and aceto-arsenite of Cu are common green pigments. Identification of Acetates. Odor of HC 2 H 3 O 2 when heated with H,SO 4 ; apple-like odor of acetic ether on adding alcohol. Deep-red color [Fe,(C 2 H 3 O 2 ) 6 ] with neutral Fe 2 Cl 6 ; color discharged both by HC1 and HgCl 2 . VALERIANATES. These yield the characteristic odor of valerian when warmed or moistened. The official salts are those of NH 4 , Fe, and Zn. They are soluble in water and in alcohol. Identification of Valerianates. Odor of valerian on heating with H 2 SO 4 ; distillate with Cu(C 2 H 3 2 ) 2 solution forms, in time, oily ppt., which gradually solidifies into greenish-blue, crystalline solid. TARTRATES. These are important medicinal salts. Soluble tartrates prevent precipitation of ferric and other hydroxids by alkalies, forming soluble salts. KHC 4 H 4 6 appears in somewhat gritty, white, rhombic crystals, with acid reaction and pleasant taste. It is sparingly soluble in water and insoluble in alcohol. Be- 12 178 INORGANIC CHEMISTRY. cause of this fact, it is thrown out of solution as a creamy de- posit (cream of tartar) of argols during alcoholic fermentation in wine-casks. It is used largely as the acid ingredient of good baking-powders. K 2 C 4 H 4 6 is a very soluble, saline purgative. KNaC 4 H 4 6 .4H 2 forms large, colorless, slightly bitter, rhom- bic prisms, with a cooling, saline taste. It dissolves in 1.4 H 2 0, and is a useful mild hydragog. Tartar emetic, 2KSbOC 4 H 4 6 .H 2 0, is a white, crystalline substance, with sweetish, disagreeable taste, quite soluble in water, and slightly in alcohol. It is a depressing emetic, and is used as a mordant in dyeing. Compound syrup of squills contains 3 / 4 grain of this salt to the ounce, and a solution in alcohol and white wine forms official vinum antimonii. Tar- trate of Fe and NH 4 and of Fe and K are non-constipating,) soluble, garnet-red scale compounds, formed by dissolving Fe 2 (OH) 6 in the acid tartrate of NH 4 or K. Seidlitz, or com- pound effervescing, powder consists of 120 grains of Eochelle salt (KNaC 4 H 4 6 .4H 2 0) with 40 grains NaHC0 3 wrapped in the blue paper, and 35 grains H 2 C 4 H 4 6 wrapped in white paper. Identification of Tartrates. Neutral solutions (free from more than a trace of NH 4 salts) give with CaCL a white ppt., which after washing dissolves readily in cold KHO, and is again pptd. on boiling. Ca(HO) 2 in excess causes ppt. in the cold, soluble in NH 4 C1. AgNO 3 gives white ppt., turning black on boiling. Char rapidly on heating to dull redness, and give distinct odor of burnt sugar. CITRATES. These salts are prepared by dissolving hydroxids or car- bonates in H 3 C 6 H 5 7 . All have a cooling taste and are soluble except BiC 6 H 5 7 (soluble in NH 4 HO). White, crystalline salts include K 3 C 6 H 5 7 .H 2 0, Li 3 C 6 H 5 7 , and BiC 8 H B 7 . The cit- rates of Fe, Fe and NH 4 , Fe and quinin, Fe and strychnin, and of Bi and KE 4 are scale preparations. Mg 3 (C 6 H 5 7 ) 2 is official as an effervescent salt and in the liquor magnesii citratis. This last is made by dissolving Mg carbonate in a slight excess of citric-acid solution, adding syrup of lemon, placing the diluted liquid in a strong, round bottle; dropping in crystals of KHC0 3 ; then corking, wiring, and shaking till crystals are dissolved. It is a mild and pleasant laxative. Elixirs of Bi contain Bi and NH 4 citrate.. Identification of Citrates. No ppt. in the cold with CaCl, and slight excess of NH 4 OH, but on boiling white Ca :! (C fi H 5 O T ) 2 is thrown down. When ppt. filtered hot and washed with a little boiling water, ORGANIC ACID SALTS. 179 it is quite insoluble in cold KHO, but readily soluble in neutral solution of CuCl 2 or NH 4 C1 2 . Ca(HO) 2 in excess does not cause ppt. till mixture is boiled. AgNO 3 produces white ppt., but no metallic mirror on boiling. Dry citrates char slowly on heating, giving slight odor of burnt sugar. LACTATES. All are soluble to some extent in water and insoluble in ether. The official metallic lactatcs are Fe(C 3 H 5 3 ) 2 .3H 2 and Sr(C 3 H 5 3 ) 2 .3H 2 0. The former appears in sweetish, light- green needles or crusts, and is slowly soluble in H 2 0; the latter is a white, slightly bitter, granular or crystalline powder, sol- uble both in water and in alcohol. Identification of Lactates. AgNO 3 when boiled gives a dark ppt., which leaves a blue liquid on subsiding. Strong solutions of alkaline lactate boiled with HgN0 3 ppts. pink or crimson HgC 3 H 5 O 3 . TANNATES AND GALLATES. The salts of tannic acid are bitter, amorphous, and gen- erally insoluble. They are the essential ingredients in nearly all vegetable bitters and astringents (exceptions are columbo, gentian, quassia, and chiretta). Ferrous tannate is the basis of most black writing-ink. The basic gallate of Bi (dermatol) is a yellow, insoluble powder used in skin diseases. Identification. Fe 2 Cl 6 in neutral solutions gives a blue-black ppt. decolorized by H 2 C 2 O 4 . OLEATES. KC 18 H 33 2 and NaC 18 H 33 2 are the only oleates soluble in water. Acid oleates are all liquid, and soluble in oils, fats, ether, and cold absolute alcohol. The oleates of Hg 11 and other heavy metals (usual strength 2 per cent.) are used in ointments where penetrating power is desired. They are made by dissolv- ing the oxid in oleic acid. They do not stain linen or become rancid, and seem to exert considerable antiseptic action. Oleates of aconitin, veratrin, morphin (5 per cent.), quinin (25 per cent.), and other alkaloids are formed by simple solution in oleic acid. Pb(C 18 H 33 2 ) 2 , or lead or diachylon plaster, is made by boiling for several hours PbO with twice its weight of olive- oil and one-third as much water. It is a white, viscid mass, soluble in ether, and is the basis of the thirteen official plasters. Identification of Oleates. They do not separate from ether or alcohol when a hot solution is cooled. Pb (C^H^C^h is pptd. by Pb(C 2 H 3 2 ) 2 , and is almost entirely soluble in ether. 180 INORGANIC CHEMISTRY. STEARATES. Alkaline stearates are alone soluble in water. KC 18 H 35 2 is soft soap; NaC 18 H 35 2 , hard soap. Identification of Stearates. HC1 and heat separate free stearic acid, which floats as an oily liquid, and solidifies to a white mass on cooling. Pb(C 18 H 3B 2 ) 2 is insoluble in ether. FORMATES. These are all easily soluble in H 2 [except Pb(CH0 2 ) 2 and Hg(CHO) 2 ], and are strong reducing agents. They are of no medical interest. Identification of Formates. They decompose, without charring, at a red heat. Heated with H 2 SO 4 they evolve CO, which burns with a pale-blue flame. SUCCINATES. These unimportant salts are neutral (E 2 C 4 H 4 4 ) or acid (BHC 4 H 4 4 ). Alkaline succinates are soluble; others diffi- cultly or not at all. Succinates are distinguished by giving a bulky, brownish-red ppt. with neutral Fe 2 Cl 6 ; also with BaCl 2 no ppt. at first, but a white one on addition of ammonia and alcohol (distinction from benzoates). MALATES. K 2 C 4 H 4 5 occurs with the free acid in apples, currants, and other fruits. The malates are freely soluble. They are recognized by adding CaCl 2 , which gives no reaction until boil- ing or addition of alcohol, when a white ppt. is thrown down. BENZOATES. These are colorless, crystalline, soluble salts with a slight odor of benzoin. They are chiefly used as urinary antiseptics, being particularly indicated when this fluid is ammoniacal, since the benzoates are eliminated by this route as hippuric acid. Used in medicine are the benzoates of KE 4 , Li, Na, Bi, and Hg. They are prepared by neutralizing benzoic acid with the desired hydrate or carbonate. Identification of Benzoates. Fe 2 Cl 6 in solution, rendered slightly alkaline with NH 4 HO, gives flesh-colored or light-red ppt., soluble in benzoic and other acids. ORGANIC ACID SALTS. 181 SALICYLATES. These are important, white, mostly solid, deliquescent, medicinal compounds with sweetish, alkaline, nauseating taste, made by dissolving alkaline hydroxids in salicylic acid. Their specific curative effect in rheumatism is due in part to their alkaline constitution raising the alkalinity of the blood, and in part probably to a destructive action on the unknown rheumatic germs. The best-known salts are NaC 7 H 5 3 , soluble in 1.5 water and in 6 alcohol; and LiC 7 H 5 3 , also very soluble. The disagreeable taste can be disguised to some degree by giving the salt in some aromatic water: cinnamon or peppermint, for example. Bi(C 7 H 5 3 ) 3 is a white, odorless, tasteless, insoluble powder, used as an internal and intestinal antiseptic and astrin- gent. Identification of Salicylates. Fe 2 Cl 6 gives a reddish-violet color, even in very dilute solutions. Methyl-salicylate, formed by warming a salicylate with alcohol and one-fourth the volume of H 2 S0 4 , is recognized by the odor of winter- green. CARBOLATES, OR PHENATES. Carbolic acid unites with bases to form soluble antiseptic carbolates, which are capable of dissolving large quantities of phenol. NaC 6 H 5 appears in fusible, pinkish needles, and is used in dentistry as an astringent, styptic, and disinfectant. Phenol-mercury [Hg(C 6 H 5 0) 2 ] is a yellow, crystalline substance made by the reaction between an alcoholic solution of NaC 6 H 5 and of HgCl 2 . Identification of Carbolates. Fe 2 Cl 6 causes a reddish-violet color. Odor of carbolic acid is evolved on heating alone or with H 2 SO 4 . SULPHOCARBOLATES. When carbolic acid is dissolved in H 2 S0 4 , sulphocarbolic acid, C 6 H 4 OHS0 3 H, is formed, and this on dilution and mixture with oxids, hydrates, or carbonates yields colorless soluble sul- phocarbolates. NaC 6 H 5 S0 4 .2H 2 and Zn(C 6 H 5 S0 4 ) 2 .H 2 are both valuable intestinal antiseptics, the latter salt being also astringent. Identification of Sulphocarbolates. Similar reactions as carbo- lates, but also give reaction of sulphates with BaCl 2 after fusing with KN0 3 and redissolving residue in dilute HC1. MECONATES. The opium alkaloids occur, for the most part, as meconates (R 2 C 7 H 2 7 .3H 2 0). Normal alkaline salts are soluble in water; 182 INORGANIC CHEMISTRY. the acid salts very slightly. Meconates of the heavy metals are soluble in HC 2 H 3 2 . Meconates are readily recognized by striking with Fe 2 Cl 6 a red color, not cleared up by HgCl 2 or dilute HC1. CYANO-SALTS. General Characteristics. Generally poisonous, mostly col- orless, prismatic; odor of HCN or bitter almonds on wetting or heating with acids; sharp, slightly bitter, alkaline taste; alkaline and alkaline earthy salts and Hg(CN) 2 soluble in H 2 0, and sparingly or not at all in alcohol (except cyanates). The soluble cyanids dissolve insoluble ones, forming double salts. CYANIDS. KCN is a deliquescent compound, soluble in 2 H 2 0, used for reduction of metallic oxids, and especially as a solvent of Ag salts in photography and of Au and Ag in electroplating and in the extraction of Au from its ores. AgCN and Hg(CN) 2 are white powders, turning dark on exposure to light. The isocyanids, isonitrils, or carbylamins are non-toxic liquid hy- drocarbon derivatives with an extremely offensive odor. Identification of Cyanids. AgNO 3 in excess gives a curdy, white ppt., soluble in NH 4 HO and in strong boiling, but not dilute, HN0 3 ; ppt. turns brown on exposure to light. Insoluble cyanids yield (CN) 2 , smelling like peach-kernels, when heated in dry test-tube; draw out open end into jet and light gas, which shows a purple-red flame. CYANATES, OR ISOCYANATES. KCNO appears in white scales, and is employed in the preparation of organic compounds. NH 4 CNO is a white, crys- talline mass, which changes to its isomer urea on heating. Identification of Cyanates. On moistening they yield the corre- sponding bicarbonate. SULPHOCYANIDS, SULPHOCYANATES, OR THIOCYANATES. KCNS, NaCNS, and KH 4 CNS give a blood-red color with ferric compounds, and are used to distinguish ferric from fer- rous salts. Hg(CNS) 2 is a white, insoluble powder, which swells up greatly on decomposing by heating, and is used in the cone- shaped toys called "Pharaoh's serpents." Identification. On heating with H,S0 4 , HCN is evolved, with characteristic odor, and S is deposited. Also the ferric test mentioned above. QUESTIONS. . 183 FERROCYANIDS. K 4 Fe(CN) 6 .3H 2 is manufactured on a large scale by fusing horns, hoofs, leather, etc., with potash and adding iron. It appears in yellow crystals, used in dyeing and in making KCN, HCN, and the pigment Prussian blue, Fe 4 (FeCy 6 ) 3 . Identification of Ferrocyanids. Any ferrous salt gives a white ppt., quickly changing blue; any ferric salt a dark-blue ppt. of Prussian blue, insoluble in HC1, turned reddish brown by KHO, the blue color being restored by adding HC1. Pb, Zn, Ag, and Hg solutions give white ppts.; cupric salts a reddish-brown ppt., insoluble in acids, but soluble in NH 4 HO. FERRICYANIDS. These salts are produced by oxidation of solutions of the ferrocyanids with 01. The is given off in the presence of free alkali, red prussiate of potash [K 6 Fe 2 (ClSr) 12 ], changing back to yellow prussiate, or ferrocyanid. Identification of Ferricyanids. Any ferrous salt ppts. dark Turn- bull's blue [Fe : ,Fe 2 (CN)i 2 ], insoluble in acids, decomposing with boiling KHO into K 6 Fe 2 Cy 12 and dirty green Fe(HO) 2 . Any ferric salt gives a brownish coloration, and throws down Turnbull's or Prussian blue on adding reducing agents (H 2 S0 3 or SnCl 2 ). Lead and mercuric salts give no ppt.; stannous salts, white ppt.; mer- curous solutions, brownish red; AgNO 3 , orange. NITROPRTJSSIDS. These salts are formed by the action of HN0 3 on ferro- cyanids, NO replacing a CTN". The only one of practical in- terest is sodium nitroprussid [Na 2 Fe(CN) 5 NO.H 2 0], which appears in red prisms and is used as a reagent. QUESTIONS ON INORGANIC CHEMISTRY. Metals. 1. Name the alkali metals and the metals of the alkaline earths. 2. Which is more potent, KBr or NaBr, and why? 3. If a cubic inch of Fe and a cubic inch of Sn were both heated to the same temperature and placed on a cake of paraffin, which would melt the wax first? 4. What metals decompose H 2 0, and why? 5. Write equation for decomposition of H.,0 with red-hot Fe. 6. W 7 hat two metals rank first as conductors of heat and elec- tricity ? 7. W r hy do silver spoons tarnish? 8. How can one separate Hg from other metals? 9. At what temperature does Hg distil? 184 INORGANIC CHEMISTRY. 10. What objection to sterilizing Al instruments by boiling with a soda solution? 11. Why is the solution blue when a silver coin is dissolved in HN0 3 ? 12. Why should H 2 O 2 be measured in a glass graduate? 13. Reasoning from the dose of liquid preparations of As, what should be the dose of solid preparations? 14. When a child is given full doses of a Bi compound, what should one say to the mother about the stools? 15. What is the m.p. of Pb, of Sn, and of soft solder? 16. How does aqua regia dissolve Au and Pt? 17. How distinguish "mystery gold" from true gold? 18. What carat is United States gold coin? 19. What is iron-rust? 20. What is the theoretic m.p. of Wood's fusible metal? 21. Is an alloy of Au and Ag accompanied by expansion or con- traction? 22. What is the weight of a cubic foot of Au? 23. Name five natural compounds of Al. 24. Why did the bronze precede the iron age? 25. What are the chief uses of Pt? 26. Compare Al and Sn for domestic purposes. 27. What is the sp. gr. of Al, Cu, Fe, Ag, and Au? 28. Explain the chemic principle of "sympathetic inks." 29. How does Hg produce medicinal effects? 30. Why are Ag salts used in photography? 31. Why does Cu turn green in moist air? 32. How may taking S internally tarnish a silver dollar in the pocket ? 33. To what is the color of common rocks due? 34. What are "blacksmiths' scales"? 35. How do so many ores occur as sulphids? 36. Why are Fe salts often saccharated? 37. Why are alloys generally preferable to single metals? 38. Why are sand and lime used in the roasting and extraction of metals ? 39. What are the chemic differences between wrought Fe, cast Fe, and steel? 40. Why is Sb used in type-metal? 41. Why are Fe retorts used in separating Hg from other metals? 42. Why do dental fillings discolor in the mouth? 43. Why is Fe administered in blood diseases? 44. Why are the alkali metals kept in benzene? 45. Determine the carat of an alloy containing 8 parts Au, 2 parts Ag, and 2 parts Cu. 46. How much pure gold must be added to 10 gm. of 18-carat gold to raise it to 22-carat? 47. How could you reduce 10 gm. of pure gold to 14-carat ? Metalloids. 1. What is the most abundant element in Nature? 2. What is the valence, atomic weight, and density of H? 3. What are the chief uses of O in Nature? 4. Give the derivation of five elements named after some physic property. 5. How could you prove the presence of H in any compound? QUESTIONS. 185 6. What simple gas can be collected by upward displacement, and which by downward displacement? 7. How detect decomposition of Cl water into HC1? 8. What element is noted for its unstable compounds? 9. Describe the chief chemic interrelation between plants and animals. 10. To what is the luminosity of P in H 2 due? 11. What is the principal source of P and its compounds? 12. Sound travels four times as fast in H as in 0. Why? 13. How does Cl destroy the odor of sewer-gas? 14. State the density and molecular weight of ozone. 15. Name six chief components of the atmosphere. 16. How is air liquefied? 17. What difference between atmospheric air and that absorbed by HXD? 18. What danger of lead poisoning is there from chewing lead- pencils? 19. Describe three allotropic forms of C. 20. Why is it harder to light a fire of coke or hard coal than one of soft coal? 21. Write equation for formation of S in Nature. 22. For what two poisonous metals has H a great affinity? 23. Name the halogens. 24. What is the chief source of Br? 25. Why are C and Zn used in batteries? 26. How do leguminous plants restore the fertility of fields? 27. What is vulcanized rubber? 28. Why is a partly burned match black? 29. Why is a good draught needed for a good fire? 30. How does charcoal deodorize? 31. Why does a lamp-chimney smoke when the wick is turned low or too high? 32. How does Cl bleach? Oxids. 1. What fractional part of H 2 are O and H, by weight and by volume? 2. Why does boiled H 2 taste flat? 3. Why is rain-water purer than that from ponds or rivers? 4. What are anhydrids? 5. Distinguish between deliquescent and efflorescent substances. 6. How does boiling soften water? 7. How does washing-soda soften water? 8. To what is the color of most crystals due? 9. Why is natural water never pure? 10. How can one make fire from water? 11. How can one prove that water is a product of fire? 12. What are the chief uses of Ba0 2 ? 13. What advantage in using H 3 P0 4 or H 2 SO 4 rather than HC1 in preparing H 2 O 2 ? 14. Write equation representing some chemic reaction into which H 2 enters. 15. Why are halogen oxids very unstable? 16. What is the valence of I in its oxid? 17. Why is SCX always present in city-air? 186 INORGANIC CHEMISTRY. 18. How does S, thrown on the fire in a stove or grate, extinguish the fire in a burning flue? 19. Is CO heavier or lighter than air? 20. What percentage of weight is lost in converting magnesium carbonate into the oxid? 21. How may we render a Mg solution alkaline without precipita- tion? 22. How does calcining ZnO for dental cements get rid of con- taminating As? 23. What is the chemic composition of the black scales on heated Cu? 24. What color does red lead turn on heating, and why? 25. On what does the cauterant action of Cr0 3 depend? 26. What makes the stalks of grain stiff? 27. What is a grain of sand, chemically speaking? 28. What is "petrified wood"? 29. Write equation for preparation of laughing-gas. 30. How does lime slake? 31. Why does "soda-water" effervesce? 32. How does S0 2 decolorize objects? 33. What is the chemic fire-extinguisher? Acids. 1. Mention the general characteristics of hydro-acids. 2. What causes the white film on the inside of a bottle of HC1? 3. Write equation for reaction producing the white cloud when the open mouths of a bottle of HC1 and of NH 4 HO are brought near together. 4. In what part of the human body does free HC1 occur? 5. How make official dilute HC1 from the strong acid? 6. Show by equation how tree Cl is produced in aqua regia. 7. If a cold, dilute solution of starch and KI give a blue color with HC1, what impurity is indicated? 8. What kind of a stain is produced on black cloth by HC1, HN0 3 , and H,S0 4 ? 9. How does dilute H 2 SO 4 act as an astringent? 10. Write equation for reaction of HNO 3 on Cu. 11. Why is HI usually prescribed as a syrup? 12. Show by equations the relations of the acids of P. 13. What weak acid breaks up as soon as formed? 14. What acid is a strong bleaching and disinfectant agent? 15. What is silicic acid? 16. What acid imparts a green color to flame? 17. If a H 2 S generator were leaking at some point, how could one determine the point? 18. To what is the bad smell of rotten eggs due? 19. What acid liberates most other acids from their salts? 20. Write equation for a mixture of H 2 S0 4 and H 2 0. Bases. 1. What are the caustic alkalies? 2. W T hat is the density of NH 3 ? Is it heavier or lighter than air? 3. How could you prepare the hydroxid of any of the metals ex- cept of the alkalies and alkaline earths? QUESTIONS. 187 4. Calculate how many volumes of MH 3 are required to make a 10-per-cent. solution, by weight, in H,O. 5. Explain appearance of white scum on lime-water exposed to the air. 6. Why is Ca(HO) 2 nearly twice as soluble in cold as in boiling water? 7. What is "milk of magnesia," and for what is it used? 8. What hydrate is used extensively as a mordant? 9. How make "black wash" and "yellow wash"? 10. What is dialyzed iron? Salts. 1. How can one remove the purple stain of AuCl ? from the hands? 2. Reason out a method for removing AgN0 3 stains from the skin. 3. What are the products resulting from heating KC10 3 ? 4. Represent, by an equation, the action of vinegar on chlorinated lime. 5. Explain the color-change in identification of hypochlorites. 6. Which official bromid contains the greatest percentage of Br, and hence is most hypnotic? 7. Explain color-change and use of chloroform in Cl test for bro- mids. What would a violet color indicate? 8. What amount of KI is required to make a saturated aqueous solution? 9. Why is sugar used with the licorice-root in pil. ferri iodid? 10. Explain why the protiodid of Hg is sometimes yellow in color, sometimes green. 11. How detect the contaminating presence of red lead or Hg in vermilion? 12. How would you prepare a solution of Ca(SH) 2 ? 13. Explain setting of plaster of Paris. 14. How much ZnS0 4 will 10 gm. Zn yield? 15. What change in appearance of white lead and of Bi subsalts on heating (200 or more), and why? 16. How detect adulteration of white lead with BaSO 4 ? 17. Why is good baking-powder preferable to saleratus? 18. Write equation for raising of bread with baking-powder. 19. Why cannot NaN0 3 be used in gunpowder? 20. What should be the color of a mixture of bromid and iodid tested with starch and Cl water? 21. Mention the only insoluble Li salt. 22. What precautions should be observed in evaporating hypo- phosphite solutions? 23. What colored ppt. does (NH 4 ),Mo0 4 yield with a mixture of phosphates and hypophosphites? 24. What pigments would you mix to get chrome-orange? 25. Explain ppt. of argols during vinous fermentation. 26. Is FeC 2 O 4 soluble or insoluble? 27. What solvents are of aid in removing ordinary plasters from the skin? 28. How does AgNO 3 dye the hair? 29. Why is the caustic action of lunar caustic superficial? 30. Why do dental cements give way more rapidly near the gum- margin ? 31. Write equation for firing a gun. 188 INORGANIC CHEMISTRY. 32. What salt is formed in making H in the laboratory? 33. What makes some waters hard: temporary and permanent? 34. Why are ternary halogen salts unstable? " 35. Give the common name and formula of the chief salt of Sb. 36. What is the chemic nature of glass, and how is it colored? 37. What changes take place in the drying of wall-plaster? 38. What group of metals has the most soluble salts? 39. What is the chief medicinal compound of Mg? 40. What is the "bichlorid of gold"? 41. Write the graphic formula of ferric bromid. 42. What is the chief use of the salts of Sn? 43. From what two localities are Ni and Co -ores generally ob- tained ? 44. What is the only medicinal salt of Ce? 45. Explain the use of borax in welding. 46. Why should acids not be given with calomel? 47. How does cement harden under H,0? 48. Why does a white-painted house turn dark in time? THE CARBON COMPOUNDS. THE term organic was formerly applied to compounds de- rived directly or indirectly from living organisms; all others were called inorganic or mineral. This distinction was first broken down by Henry Hennell, who in 1826 made alcohol from coal-gas; and again in 1828 by Wohler, who obtained urea by warming ammonium cyanate produced in the laboratory. Since then the synthetic manufacture of drugs formerly prepared only in Nature's laboratory by the supposed "vital force" has risen to immense proportions. As an example of such synthe- sis, acetylene-gas, C 2 H 2 , can be made by direct union of C and H in the electric arc, ethylene may be prepared from acetylene by the action of nascent H; and ethyl alcohol is obtainable from ethylene by treating the latter with H 2 S0 4 and H 2 0. Ordi- narily synthetic preparations are derived from natural products and by-products, particularly coal-tar, which is the source of a great number of dyes and medicines. It will be seen that the term organic chemistry has lost all its former significance, and is now simply a convenient name for the science of the carbon compounds. Test for Organic Substances (that is, for Carbon). Heat sugar or other C compound on Pt foil till it chars. Keep heating, and it all burns away unless some impurity or a metallic salt of an organic acid is present. Treat sugar with H 2 SO 4 and note the charring, owing to the acid taking H and O, or water, away and leaving the C. A better test is to mix the sugar with ten times its weight of CuO and heat to redness in a narrow tube sealed at one end, passing the gases (CO 2 , etc.) into lime-water. C has a wonderful capacity for uniting with itself and H to form a great variety of compounds. Along with 0, these two elements make up most vegetable substances. Animal sub- stances contain, in addition, N and sometimes S and P, Cl and I. Test for H. Heat sugar in a dry test-tube and note cloud of vapor in upper, cooler part of tube. Test for 0. Show that absolute alcohol oxidizes Na, whereas ben- zene, C 6 H 6 , does not. Test for N. Heat white-of-egg disks on Pt foil, and note odor of burning feathers; or heat in a hard-glass tube with soda-lime (equal parts NaHO and CaO) and mark odor of NH 3 . (189) 190 THE CARBON COMPOUNDS. A more delicate test is to heat a small disk gradually to a red heat in a narrow test-tube with a piece of Na the size of a pea. Allow to cool a little, and break off hot end by immersing in a little water in an evaporating-dish. Then filter off the C ; add a few drops of FeS0 4 , and warm; acidulate with HC1, and test with a drop of Fe 2 Cl 6 , forming blue Fe 4 (FeCy 6 ) 3 . GNaCN + Fe ( HO ) 2 = Na 4 Fe ( CN ) 6 + 2NaHO Test for S by boiling white of egg in an alkaline solution of Pb(HO) 2 , getting dark ppt. of PbS. Test for P by fusing yelk of egg on Pt foil with KNO 3 and K 2 C0 3 till the residue is colorless. Dissolve this in H 2 0, and, after pptg. sul- plates with BaCl 2 , filter and throw down phosphates with (NHJ 2 Mo0 4 in HN0 3 . We may also oxidize the substance by heating in a sealed tube with HN0 3 . H 3 PO 4 is formed, and is recognized by the usual tests. Test chloroform for Cl by mixing it with pure CuO and igniting on Pt wire. Cl (and Br) gives a blue color, changing to green; I a green color. The wire should first be held in the flame till colorless. The empiric molecular formulas of organic substances are obtained by dividing the percentage of each element by its atomic weight to get the ratio of the elements; then taking as many atoms of each element in these ratios as will make up the molecular weight, which is twice the vapor-density (see "Analytic Chemistry"). Example. Formaldehyd contains 40 per cent, of C, 6.66 per cent, of H, and 53.34 per cent, of 0. These numbers divided, respectively, by the atomic weight of each element give the proportion of 3.33 atoms of C, 6.66 of H, and 3.33 of O, or 2 of H to 1 each of C and 0; hence the percentage composition is CH 2 O. The vapor-density of formaldehyd is 15; hence the molecular weight is 30, which corresponds with the weight of the molecule CH 2 O (12 2 16). The correct formula is therefore CH 2 O. Acetic acid shows the same percentage composition as formaldehyd, but its vapor-density and molecular weight are twice as great; hence its formula should read C 2 H 4 2 . Again, lactic acid has the empiric formula C 3 H 6 3 ; since, while the elements are in the same proportion as in formaldehyd, the molecular weight is 90 in place of 30. Organic compounds are separated and purified in three ways: 1. By shaking or boiling with alcohol, ether, benzene, and chloroform, in all of which inorganic compounds are gen- erally insoluble. A mixture of tartaric acid, benzoic acid, and sugar can be separated, the first by alcohol, the second by ether, and the third with H 2 0. 2. By crystallization from the various solvents above mentioned. Two or more substances may some- times be separated by fractional crystallization. 3. By distilla- tion, especially fractional, as in the parting of alcohol and water. The process is sometimes conducted in a current of HYDROCAKBONS. 191 steam or under reduced pressure. The m.p. of pure substances is always definite; of impure substances indefinite and gradual. By eremacausis is understood the natural slow combustion or decay of organic substances. Proteins putrefy into bad- smelling,, alkaline products. Carbohydrates ferment into C0 2 and other acid products not usually of a bad odor. Chemic changes in plants are generally constructive, or synthetic; those in animals,, destructive, or analytic. Thus, plants build up C0 2 and H 2 into starches and sugars, which are broken down again in the animal organism into H 2 and C0 2 . HYDROCARBONS. Hydrocarbons are simply compounds of C with itself and H. Of these there re a great number, some of the most im- portant being arranged in the following table. They are, for the most part, vegetable products, directly or indirectly, ana- lytic or synthetic, being built up by plants from the C0 2 and H 2 of the air. NOMENCLATURE OF HOMOLOGOUS HYDROCARBONS. SERIES I. SERIES II. SERIES III. SERIES IV. SERIES V. PREFIXES. Parnffin.1 (CnH 2 n + 2). Olefin* (CnH 2 n). Acetylenes (CnH 2 u-2). Te.rjtf.nes (CnH 2 n-4). Benzenes (CnH 2 n 6). Meth- ane = CH 4 Eth- C 2 He ene or ylene = C2H 4 ine = C 2 H 2 Prop- = C 3 H 8 " " =C 3 H 6 " =C3H 4 one = C 3 H 2 But- = C 4 Hio " " = C 4 H 8 " =C 4 H 6 " =C 4 H 4 une = C 4 Hs Pent- = C 5 H 12 " " = CsHjo " = CsH 8 " =C 5 H 6 " =C 6 H 4 Hex- ^C^,, = CeH 12 = C 6 H 10 -C 6 H 8 " =C 6 H 6 The arbitrary arrangement given above is designed as a simple plan for designating hydrocarbons according to their exact composition. It will be noted that the prefix meth indi- cates 1 atom of C; eth, 2 atoms; prop, 3; but or quart, 4; pent or amyly 5; hex, 6; Tiept, 7, etc., with the use of Greek numerals. It is also seen at a glance that the suffixes indicating the series are in the order of the vowels of the alphabet, and that each member of a series is 2 H less than the corresponding member of the preceding series, as shown in a general way by the alge- braic formulas. Hence it is an easy matter to deduce the name from the formula, or vice versa. The sixth series is known as the cinnamene; the eighteenth as the anthracene. 192 THE CARBON COMPOUNDS. Homologous hydrocarbons differ by CH 2 , and hence belong to the same series. Isologues differ by H 2 , and are correspond- ing members of adjacent series. Isomers, or metamers, are compounds having the same composition, but different consti- tutions: i.e., the atoms of the molecules are not arranged in the same order; they have also different physic properties. These variations are accounted for by a difference in the rela- tive positions of the atoms: i.e., the way they face each other. Stereo-isomerism is the term applied to differences solely in physic properties of certain compounds having the same molec- ular and constitutional formulas. The usual formula is called normal or primary, and has 1 C linked to no more than 2 other C atoms. In iso, or secondary, compounds 1 C is linked to 3 others; in meso, or tertiary, to 4; in neo, 2 to 3. The number of possible graphic isomeric formulas for the fourth member of the first series is 2; for the fifth, 3, for the seventh, 7, for the eighth, 18, and so on by permutation to 802 for the thir- teenth member. Polymeric compounds are multiples, the one of the other: e.g., propene and hexene. The members of the first four series are comparatively easily broken up, and hence are arranged graphically in open chains, as ethane: H H H C C H I I H H The carbon nucleus of the fifth series is very permanent, hence is represented as a closed chain or ring. The unsaturated nature of the members of all the series except the first is rep- resented rationally by double or treble bonds or linkings be- tween C atoms; thus, ethene: H r r H H L L H By dropping an H from any of these formulas a monad radical is obtained. Such hydrocarbon, alcohol, or alkyl rad- icals are electropositive, and are named with the usual prefix, but with the ending changed to yl (occasionally enyl or ylene when 2 or 3 H are removed). Examples are: CH 3 , methyl; C 2 H 5 , ethyl; C 5 H 12 , pentyl or amyl; C 6 H 5 , hexyl or phenyl. PARAFFINS, OR FATTY SERIES. This series differs from the others in its members being saturated; hence, stable. All are neutral, combustible, and lighter than H 2 0. The name paraffin indicates "little affinity," HYDROCARBONS. 193 or chemic inertness. The first four members of the series are gases; the next twelve oily liquids at ordinary temperatures; the higher members are fatty and waxy solids. Atmospheric converts many of the liquids into solids. The members of this series are thought to have originated by destructive dis- tillation of the fatty remains of sea-animals in the lower layers of the earth's crust. Methane, or "marsh-gas," is a colorless, tasteless, odorless gas formed by decay of vegetable matter under H 2 0. It con- stitutes 90 to 95 per cent, of natural gas and 30 to 40 per cent, of ordinary coal-gas (6 to 12 per cent, of water-gas). It often collects in large quantities in ill-ventilated coal-mines ("fire- damp"), where it may take fire and give rise to terrible ex- plosions. Experiment. Prepare pure CH 4 by heating 1 part NaC 2 H 3 O 2 with 4 parts soda-lime, collecting over H 2 0. Note blue flame when burned. This is a sign of danger when seen within the Davy safety-lamp of miners. Ethane is also present at times in natural gas. Butane, or quartane, is a gas which when liquefied (cymogene) is used in ice-machines. Ehigolene is a hydrocarbon mixture used as a local anesthetic by evaporation. Petroleum is an extremely important natural mixture (up to C 16 H 34 ) obtained from wells and furnishing most of the members of this series. In the crude form it is a thick, brown or yellow liquid. Among the products of its fractional distilla- tion (with b.p.) are cymogene (0); rhigolene (21); benzin (50 to 60); gasolene (75); naphtha (82 to 149); ligroin, or light petroleum; cleaning oil (120 to 170); kerosene, or refined petroleum (150 to 250); mineial sperm-oil (218); lubricating oil (301); paraffin (melts at 45 to 65); vaselin (soft, melts at 40 to 45; hard, at 45 to 51); and coke, or petroleum pitch. All fractions are purified by treating with H 2 S0 4 , then washing, then rendering alkaline. Some of these compounds are derived from the dry distillation of soft coal, bitumen, shaly wood, ozokerite, and fish-oil. Petroleum com- pounds are characterized generally by more or less fluorescence. They are soluble in ether, chloroform, CS 2 , benzin, benzene, turpentine, and oils. Benzin, benzolin, or petroleum-ether (mixture of pentane and hexane) has a sp. gr. of 0.67 and is a good solvent for oils, fats, resins, and rubber. It remains semiliquid at 175. It is used to remove grease-spots and for varnishes and paints. Clothing saturated with benzin may take fire in direct sun- light. 13 194 THE CARBON COMPOUNDS. Naphtha appears in three forms (A, B, and C), with differ- ent b.p's. It is the so-called safety-oil, and is used as a solvent for oils, fats, resins, and rubber. Cleaning oil, as the name suggests, is used for cleaning purposes and also in place of tur- pentine in varnishes. Gasolene is highly inflammable, and is used in special stoves and for running automobiles. Kerosene, or coal-oil, should not "flash" (yield an inflam- mable-gas) below 120 F. or ignite itself under 300 F. Experiment to Test Flashing-point of Kerosene. Fit a large test- tube with a perforated cork provided with a bent glass tube and a thermometer. Pour about 15 c.c. of kerosene into the tube, and heat very gradually. Agitate surface of liquid at frequent intervals by blowing through glass tube; then apply a flame to mouth of test-tube, repeating the trial until the flame flashes down into the tube. Vaselin, cosmolin, or petrolatum, is a mixture of the upper half-series of fatty, yellowish hydrocarbons. It is purified and decolorized by passing through bone-black. Liquid petrolatum (sp. gr., 0.875 to 0.945) is a useful sedative application to mu- cous membranes. The solid (hard and soft) is used as an oint- ment-base. Paraffin (sp. gr., 0.877) is the waxy residue left after dis- tilling off the above-named products. Ozokerite, or mineral wax, consists largely of paraffin, and is used in the preparation of ceresin, a substitute for wax. Paraffin is acted on hardly at all by the strongest chemicals, for which reason it is used on the glass corks of reagent bottles. It is also utilized exten- sively for candles. Photogene and solar oil are distilled from the tar left after the destructive distillation of cannel-coal or shale in the pro- duction of paraffin. They are used as solvents and illuminants. Coal-gas is made by the destructive distillation at bright- red heat of bituminous coal in fire-clay or cast-iron retorts. The gaseous products are passed through the hydraulic main, a series of tubes partly filled with H 2 0, where the steam, tar, and NH 3 are condensed; then into the scrubbers (columns of coke over which water trickles); then through a number of large boxes with perpendicularly arranged shelves, where the gas is purified (of H 2 S, C0 2 , CS 2 , S0 2 , and volatile oils) with freshly slaked lime, a mixture of sawdust and oxid of Fe, etc.; and thence to the gasometer, a large, tub-shaped, iron storage- vessel, floated upside down on water. A ton of coal yields 10,000 to 12,000 cubic feet of gas. The specific gravity of coal- gas is from 0.65 to 0.75. Water-gas is made by the alternate action of air and steam on anthracite coal at a red or white heat. The gaseous product HYDROCARBONS. 195 is mixed with naphtha-vapor, strongly heated in tubular re- torts, and purified as above. Being cheaper, though much more poisonous (four or five times as much CO) it is very largely used for heating and illuminating purposes. The chief ingre- dients in both kinds of gas are CO (5 to 25 per cent.), H (30 to 50 per cent.), CH 4 (20 to 40 per cent.), C 2 H 2 , C 2 H 4 (4 to 10 per cent.), N, and C0 2 . The by-products in the manufacture of coal-gas are of vast importance, particularly NH 3 and coal-tar. About 150 more Fig. 29. Manufacture of Coal-gas. or less valuable chemic compounds are obtained in this way. They are separated by differences in solubility, b.p., sp. gr., or chemic reaction. Experiment. Heat sawdust in an ignition-tube, and notice in- flammable gas, tar, charcoal, and acetic acid. Natural gas is chiefly CH 4 , with some C 2 H 6 , C 3 H 8 , H, etc. It is probably a product of past decomposition of organic matter pptd. from water in stratified rocks and subjected to heat and pressure. The C0 2 of springs and soils may have originated in the same way. OLEFINS, OE ETHYLENE SERIES. This series is comparatively unimportant. Its members are prepared by destructive distillation of fats, waxes, coal, and 196 THE CARBON COMPOUNDS. lignite. The first three are gases, the following four volatile liquids, and the sixteenth and higher solids. They are mostly soluble in ether and alcohol, and are readily oxidized by Cr0 3 or K 2 Mn 2 8 . The principal member is ethylene (C 2 H 4 ), or olefiant gas, so called because it forms a colorless, oily liquid (C 2 H 4 C1 2 ) with Cl; this fact also accounts for the name of the series. About 6 per cent, of coal-gas consists of C 2 H 4 , to which the luminosity is largely due. It has a peculiar, sweet smell. Pentene, or amylene, has been used as an anesthetic under the name of pental. It is obtained by dehydrating amyl alcohol, and has an odor like mustard. ACETYLENES. This series is so named after ethine, or acetylene, a color- less gas with a sharp, garlicky odor, formed by incomplete com- bustion when a lamp or gas-jet is turned low. It is prepared commonly by decomposition of CaC 2 with H 2 0. Experiment. To some lumps of calcium carbid add water, and light evolved gas. It has ten times the illuminating power of ordinary gas, and is not so poisonous, but may explode when mixed with air. On heating it is converted into benzene (C 6 H 6 ) or styrene (C 8 H 8 ). Propine is commonly known as allylene and allene (isomeric gases), and butine as crotonylene. TERPENES, OK TRITONES. This series comprises most oleoptens or essential oils of plants, used for odor and flavor, and obtained generally by dis- tillation, sometimes by pressure, fermentation, or solution in fixed oils. They leave no permanent stain on paper, being volatile. They are mostly lighter than H 2 and quite soluble in alcohol, strong solutions being termed essences, weaker solu- tions (10 per cent.) spirits. They are fairly soluble in ether, but in H 2 only to the extent of 1 m. per fluidounce, forming aquae. Many of them are isomeric or polymeric with turpen- tine, C 10 H 16 , and they tend to polymerize to C 15 H 24 or C 20 H 32 when heated in a sealed tube or shaken with H 2 S0 4 . The crude oil of turpentine, the juice of the pine, when distilled leaves common rosin, which is used in some official plasters. The sp. gr. of turpentine is 0.86. It is a good solvent for resins, paints, S, and P. On exposure to air, like other vola- tile oils, it absorbs as ozone, and becomes resinous, which explains its drying action in paints. The acid, or French tur- HYDROCARBONS. 197 pentine, thus obtained is used as an antidote for P poisoning. Terebene, terpin, and terpinol are valuable medicinal deriva- tives of C 10 H 16 . They are stimulants because they are volatile. When C 10 H 16 is treated with H 2 S0 4 white crystals of terpin hydrate, C 10 H 16 .3H 2 0, are formed. Volatile oils may be classified as follows: 1. True terpenes (C 10 H 16 ): Bergamot, birch, chamomile, caraway, dill, hops, juniper, lemon, myrtle, nutmeg, orange, parsley, pepper, rue, savin, thyme, Tolu, turpentine, and vale- rian. 2. Cedrenes, or sesquiterpenes (C 15 H 24 ): Calamus, casca- rilla, cedar, cloves, cubebs, patchouly, and rosewood. 3. Aromatic aldehyds: Almond and cinnamon. 4. Compound ethers: Mustard and wintergreen. The third and fourth classes are a little heavier than H 2 0. Most essential oils contain also some oxidation products in the form of stearoptens. Caoutchouc is a hard, tough polyterpene, soluble in CS 2 , C 6 H 6 , chloroform, and ether. When heated with 7 to 10 per cent, of S at 130 to 150 it yields black, vulcanized rubber, which is more elastic and less affected by chemic agents. Hard rubber (vulcanite, ebonite) contains from 20 to 35 per cent, of S. Dental rubber is colored with vermilion, ZnO, CaC0 3 , and white clay. Eubber plasters have as a basis cleansed and rolled Para rubber with olibanum (true frankincense), purified pitch, etc. When they become brittle and non-cohesive, they can be temporarily restored by warming and wetting with alcohol. Gutta-percha is harder and more tenacious, and can be molded in hot water into splints. A solution in chloroform is known as traumaticin, and is used as a dressing for slight wounds. Gutta-percha is also employed by dentists as a plastic filling material. Stearoptens, or camphors, are solid, volatile, oxidized es- sential oils, therefore insoluble in H 2 0, but soluble in alcohol. They burn with a smoky flame, like all the rest of this series, and are medicinally stimulants. Camphor has the formula C 10 H 16 (that of Borneo, C 10 H 18 0). Monobromated camphor, C 10 H 15 BrO, is made by adding Br to a solution of camphor in chloroform. Menthol, from oil of peppermint; thymol, from oil of thyme and horsemint; and eucalyptol, from oil of euca- lyptus, are similar to camphor chemically and are characterized by a pleasant odor. Artificial camphor is a direct combination of HC1 vapor and C 10 H 16 . Experiment. Make artificial camphor by passing HC1 gas through 10 or 20 c.c. of oil of turpentine, and collect ppt. on filter. 198 THE CARBON COMPOUNDS. Eesins are solid,, brittle, amorphous, non-volatile, oxidized essential oils; acid in reaction; soluble in alcohol, ether, and oils; and pharmaceutically incompatible with H 2 0. Oleoresins contain also some unoxidized oil, and are soluble in ether and alcohol. Balsams are like oleoresins, with addition of benzoic or cinnamic acid, which gives an aromatic odor. Alcohol is their best solvent. Gum-resins are resins plus gum and sugar and up to 9 per cent, of volatile oil. They appear in milky tears, .and are best dissolved with dilute alcohol. Eubbed with H 2 in a mortar, they yield good emulsions (asafetida, white; scammony, green; gamboge, yellow). Many members of the above classes are natural vegetable exudations. Examples of Resins. Rosin, ergotin, guaiac, jalap, pyrethrum, podophyllum, lac (stick, seed, and shell), sumbul, mastic, sandarac, copal, amber, and asphalt. The last three are fossil resins. Examples of Oleoresins. Copaiba, capsicum, cubeb, lupulin, pepper, ginger, male fern, crude turpentine, Burgundy and Canada pitches, wood- oil or gurjun balsam, and various turpentines from pine-, fir-, and larch- trees. The medicinal ones are extracted, as a rule, with ether (100 to 150 parts). Wood-tar (pix liquida) is a complex mixture containing methyl alcohol, acetone, paraffin, pyroligneous and carbolic acids, etc., prepared by the destructive distillation of pines. Examples of Gum-resins. Ammoniac, asafetida, myrrh, scam- mony, galbanum, gamboge, euphorbium, and olibanum (frankincense). Examples of Balsams. Benzoin, Peru, copaiba, Tolu, and styrax. Benzoin is one-eighth to one-fourth benzoic acid. Eesinous compounds are much used in medicine as purga- tives and as mucous-membrane stimulants. The common resins are also employed in making varnishes, lacquers, and sealing- wax. Common rosin saponifies fat, and is used in making cheap soaps. The rosin oil, obtained by destructive distillation, is used with lamp-black and sealing wax in preparing printers' ink. Identification of Rosin, or Colophony. Boil a little of the powder with 4 times as much HN0 3 ; when cold, dilute with an equal amount of water and add NH 4 HO, getting a blood-red coloration. Experiment. Show how alcoholic solution of guaiac is colored blue by CrO 3 or other oxidizing agents. AROMATIC, OR BENZENE, SERIES. The chief member of this series is benzene, or benzol, C 6 H 6 , a colorless, very volatile liquid, with peculiar odor; sp. gr., 0.884; insoluble in H 2 0, and derived from coal-tar the light oil that floats on water. It is very inflammable, and a good solvent for I, P, S, fats, oils, and resins. From it are HYDROCARBONS. 199 derived most modern antiseptics, antipyretics, and dyes. Its molecule is a symmetric hexagon: . f C H C C H II I H C C H \/ C I TT Experiment. Make C 6 H 6 by heating a mixture of CaO and dry benzoic acid, passing vapors into a test-tube set in ice. Toluene, C 7 H 8 ; xylene, C 8 H 10 ; and cumene, C 9 H 12 , are also found in coal-tar. Cymene, C 10 H 14 , occurs in oil of thyme, and is closely related to the terpenes, and can readily be ob- tained from them by dehydrogenation with Br or I. Two or more benzene nuclei may be grouped together. Several uncondensed nuclei are present in the diphenyl, di- phenyl-methane, triphenyl-methane, and indigo groups. Naphthalene, C 10 H 8 , popularly known as "coal-tar cam- phor/' or "tar balls," is constituted of two molecules of benzene condensed into one, as shown by this graphic formula: II H 1 1 C C / \ / \ H C C C H II 1 1 H C \ C ^ \ C f H \ 4 C \ t C 1 1 II H Anthracene (the basis of alizarin, or artificial madder), and phenanthrene, C 14 H 10 , contain three condensed molecules of benzol: 200 THE CARBON COMPOUNDS. H H H I I I c c c H C C C C H I II I I H C C C C H \/-vx \/ c c c I I I H H H HYDROCARBON DERIVATIVES. These are of two main classes: 1. The fatty, or aliphatic, compounds of the first series, arranged in open chains. 2. The aromatic, or ring, compounds of the fifth series. In both of these groups the derivatives are produced "by substitution of other elements or radicals for one or more atoms of H in the hydrocarbon. Hence they are called substitution derivatives. Addition derivatives are formed by direct union of unsaturated (second, third, and fourth series) hydrocarbons with elements or radicals. When the C ring of benzene is broken by substitution of N for C, we have the pyridin group of compounds (quinolin by similar substitution in naphthalene; acridene from anthracene); by for C in furfuran group; by S for C in thiophen com- pounds. Pyrrol. Furfuran. Thiophen. Pyrazalon. H C C H H C C H H C C H H 2 C CH II II II II II II I II H C C H H C C H H C C H OC N \/ \/ \/ \/ N H O S NH The relations of hydrocarbon derivatives are shown most clearly by graphic formulas, substituting characteristic radicals for H in methane and in benzene. Hydrocarbons. Methane = CH 4 . Benzene = C 6 H 6 . H p H /H H L H C // \ H C C H H _i <5_ H v HYDROCARBONS. 201 Halogen Derivatives. Methyl chlorid = CH 3 C1. Phenyl chlorid = C 6 H 5 C1. H r Cl Cl H L H SulpJionic Compounds. Replace one H with HSO 3 . Alcohols, or Hydrates. Methyl hydrate = CH 3 HO. Benzyl alcohol = C 6 H 5 CH 2 HO. H p HO CHHO H L H Ethers, or Oxids. Methyl oxid = ( CH 3 ) 2 O. Benzoquinone = C 6 H 4 O 2 H r\ r\ r\ H EC-0--GI TJiio-etJiers and Alcohols. Contain S instead of O. Aldehyds (fundamental group = COH r ). Methyl aldehyd = CH 3 COH. Benzaldehyd = C 6 H 5 COH. H-o-^COH xC OH H L H Ketones (fundamental group = CO 11 ), Di-methyl ketone (acetone) Di-phenyl ketone ( benzophenone ) = (CH 3 ) 2 CO. =C H CO> F Organic Acids (fundamental group = COOHi ). Acetic acid = CH 3 COOH. Benzoic acid = C 6 H-COOH H-p-COOH H \j H 202 THE CARBON COMPOUNDS. Ammonia Derivatives: Amins (H replaced by basic radical) and amids (H replaced by acid radical). Metbylamin = CH 3 NH 2 . Phenylamin (anilin) = C 6 H 5 NH 2 . H r NH 2 H L H Carbohydrates. Sugar and starch groups of aldebyds and ketones. Phenols (HO replaces H in C 6 H 6 ). ,HO Phenyl bydrate (carbolic acid) =C 6 H 5 HO. Quinones (substitute benzene compounds 2O for 2 H). Benzoquinone = C 6 H 4 2 . Nitrogen Derivatives (fundamental groups : NO 2 , nitro; NO, nitroso ; and N OH, isonitroso derivatives). Methyl nitrite = CH 3 NO 2 (an ester). Nitrobenzene = C 6 H 5 NO 2 H-r-No 2 H v> H Carbonyl Derivatives (fundamental group = CO n ). Cyanogen Derivatives (fundamental group = CN I ). Azo and Diazo Compounds. The diad group N = N is linked on both sides to a hydrocarbon radical in azo, to an acid radical and a hydrocarbon radical in diazo. Hydrazins. Aromatic substitution derivatives of NH 2 NH 2 . Alkaloids and Ptomains. Chiefly derivatives of pyridin and quinolin. Proteins. Phosphines (alkyl substitution products of PH 3 . ) Arsinea (same of As 2 O 3 ). Stibines (same of Sb 2 O 3 ). ALKYL, OR ETHEREAL SALTS. 203 The arrangement of isomeric phenyl derivatives in ortho (1 and 2), meta (1 and 3), and para (1 and 4) compounds is shown below [C 6 H 4 (HO) 2 ], Dihydroxy-benzene: Pyrocatechin. Resorcin. Hydroquinone. HO HO HO HO HO ALKYL, OR ETHEREAL SALTS. Cl and Br can act directly on hydrocarbons, replacing H; I acts indirectly. The halogen derivatives comprise many gen- eral and local anesthetics. They have a sweet, ethereal odor and taste, and are more or less volatile and soluble in alcohol and ether, and generally insoluble in H 2 0. They are liable to decompose in the light, setting free the halogen. Methyl chlorid, CH 3 C1, is prepared by heating CH 3 HO with a mixture of NaCl and H 2 S0 4 . CH 4 and Cl unite in sun- light to form CH 3 C1. It is a colorless, combustible gas, liquefy- ing at 22 or with 5 atmospheres' pressure. In the liquid form it is used as a refrigerant local anesthetic. Ethyl chlorid, C 2 H 5 C1, is a colorless liquid used as a local anesthetic. Its solution in alcohol is known as chloric ether. Ethyl bromid is a heavy, colorless liquid, boiling at 39. It has been used as a general anesthetic. By far the most important halogen derivative is chloroform (trichlormethane), CHC1 3 . It is prepared by the action of chlo- rinated lime on ordinary alcohol or acetone or (the purest) from chloral. Experiment. Make CHC1 3 by mixing in a test-tube retort chlorin- ated lime with x /4 as much acetone and 3 times as much H 2 O, and then distilling on the water-bath into a beaker. The chloroform collects as a heavy, oily liquid at the bottom of the beaker, and is separated and washed with H 2 S0 4 , treated with Na 2 C0 3 , and redistilled over CaO. 2C 3 H O + 3Ca0 2 Cl 2 = 2CHC1 3 + 2Ca(HO) 2 + Ca(C 2 H 3 O 2 ) 2 Chloroform is a limpid, caustic liquid; sp. gr., 1.49; b.p., 60. It tends to decompose in light or heat, setting free Cl and HC1 and the poisonous compound carbonyl chlorid, COC1 2 . Pure CHC1 3 evaporates without residue, is neutral to litmus, and gives no ppt. with AgN0 3 nor darkens with KHO or H 2 S0 4 . One-half to 1 per cent, alcohol is allowable, and renders CHC1 3 more stable. 204 THE CARBON COMPOUNDS. Experiment. Test some of the prepared CHC1 3 by heating with a drop each of alcoholic solution KHO and anilin. The offensive odor of phenyl-carbylamin, C 6 H 5 NC, is produced. Test another portion by boiling with a few drops of KHO and a fragment of resorcin, getting an intense-red coloration of rosolic acid. Chloral shows both of these reactions, but has a different odor. Paper dipped in CHC1 3 burns with a green mantle, and HC1 is given off. CHC1 3 is a good solvent for I, P, resins, camphor, alka- loids, caoutchouc, and fats, but its chief use is as an anesthetic, for which purpose it should always be administered with plenty of air or 0. The spirit is 10 per cent, in strength. The water is a weak, but saturated, solution prepared by shaking. lodoform (triiodo-methane), CHI 3 , is prepared by the action of I on alcohol or acetone in the presence of alkalies. It appears in microscopic, light-yellow crystals with strong saf- frony odor. It sublimes readily, and melts at 119. It is sol- uble in oils, alcohol, ether, and CHC1 3 . Its antiseptic effect depends on the liberation of I (of which it contains 96 per cent.) in presence of moisture. Experiment. Make CHI 3 by dropping a few crystals of I into quite dilute alcohol and then adding KHO drop by drop, warming gently, till the red color just disappears. When sediment has settled, examine crys- tals under microscope. On a large scale K 2 CO 3 with heat is emploved in- stead of KHO. C 2 H 5 HO + 4L + 6KHO = CHI 3 + KCHO 2 + SKI + 5H 2 Aristol is an odorless substitute for CH 3 , and is a com- bination of iodin and thymol, containing 46 per cent, of the former. Europhen, isobutyl-orthocresol iodid, is another sub- stitute. Bromof orm, CHBr 3 , is a colorless liquid, prepared similarly to CHI 3 . It resembles CHC1 3 and is used as a sedative, par- ticularly in coughs. ALCOHOLS. These are hydrates of hydrocarbon radicals. According to the number of HO groups, they are termed monatomic (mono- hydric), diatomic (glycols), triatomic (glycerins), etc., up to nonatomic. They are also classified as primary, secondary (carbinols), and tertiary, each being characterized by the funda- mental group (CH^OH) 1 , (CH.OH) 11 , and (C.OH) 111 , respect- ively. The lower members are liquids, the higher solids. Alcohols are readily oxidized: primary to aldehyds and mono- basic acids, secondary to ketones, and tertiary to simple com- pounds: ALCOHOLS. 205 CH 2 .OH -f = H 2 -f- COH COH + = COOH CH.OH + = H 2 -f CO Experiment. Add a few crystals of CrO 3 to 5 c.c. of absolute alco- hol until the vinegar odor of acetic acid is noted. Alcohols are neutral, but it is possible to replace the H of HO with a metal, forming alcoholates, such as C 2 H 5 ONa. Pri- mary monatomic alcohols are the most important, and are derived from the saturated hydrocarbons of the first series. Methyl alcohol (carbinol, wood-spirit), CH 3 HO, is present in the oil of wintergreen, but is prepared chiefly by the de- structive distillation of wood and as a by-product in beet-sugar manufacture. Its sp. gr. is 0.8; b.p., 66. It mixes with H 2 in all proportions. Its vapor is explosive. CH 3 HO is a solvent for fats, oils, camphor, and resins, and is used in the manu- facture of varnishes and organic dyes, for heating purposes, and in the preparation of methylated spirit (90 per cent, raw spirit, 10 per cent, wood spirit). The disagreeable odor and taste of commercial CH 3 HO are due to tarry impurities. The official alcohol is ethyl hydrate, C 2 H 5 HO (methyl car- binol, CH 3 .CH 2 HO). It occurs in diabetic urine, and is formed by alcoholic fermentation of glucoses: C 6 H 12 6 = 2C 2 H 5 HO -(- 2C0 2 . The fermented product is purified by distillation over dehydrating agents, such as CaCl 2 , CaO, CuS0 4 , or wood- ashes. Absolute alcohol contains less than 0.5 per cent. H 2 0. It boils at 78.5 and freezes at 130. Its sp. gr. is 0.7937. Absolute alcohol is a transparent mobile liquid, very hygro- scopic; hence it dehydrates tissues and is used to harden his- tologic and pathologic specimens for the microtome. For the same reason it is antiseptic, preventing decay and coagulating albumin. Alcohol is a good solvent for resins, alkaloids, and volatile oils. It burns with a non-luminous flame. Ordinary alcohol (sp. gr., 0.82) is 94-per-cent. strength by volume; the dilute (sp. gr., 928), 48.6 by volume, 41 per cent, by weight (52 + 48 = 96.3). Experiment. Show that ordinary alcohol contains H 2 O Dy adding to it some white anhydrous CuSO 4 . Explain color-change. Alcohol is a stimulant in small doses, and depressant and narcotic in large. In the system it is burned partly (1 Y 2 or 2 oz. daily) into C0 2 and H 2 0, the remainder passing off un- changed. In spite of this fuel action, it is not strictly a food. It causes accumulation of fat through decrease of activity and is not stored in the body. 206 THE CARBON COMPOUNDS. Experiment. Make C 2 H 5 HO by adding a little brewer's yeast to a solution of 5 gm. commercial glucose in 200 c.c. H 2 0. Let the flask stand in a warm place for a day, then distil and collect a few c.c. of the liquid. Test distillate by adding half as much H 2 S0 4 and an equal volume of K 2 Cr 2 O 7 solution. Aldehyd is formed and is recognized by its peculiar odor; the liquid turns green by formation of Cr 2 (S0 4 ) 3 . The iodoform test, already described, may also be employed. Alcoholic liquors are classified as malt-products, wines, and spirits. Malt-liquors include beer, ale, stout, and porter. These are formed by diastatic and alcoholic fermentation of malted barley. The ferment diastase in the grain on warming develops dextrin and maltose; then yeast is added to set up alcoholic fermentation. These malt-liquors contain 2 to 8 per cent, of alcohol (beer weakest, ale strongest); also C0 2 and malt-sugar. Hops are added to beer as a preservative, and glycerin to cause foam. Hard cider contains about 5 per cent, of alcohol. Wines are prepared from grapes fermented by the action of a living ferment always present on grape-stalks and in the air. If only the must, or grape-juice, is used a white wine (official, 10 to 14 per cent.) results; if the marc, or skins and seeds, is included, a red wine (same strength as white). The "ripening" of wine in casks takes from two to eight years. Champagne and other effervescing wines are bottled before fermentation is quite complete, with addition of alcohol and cane-sugar. The alcoholic strength of wines varies from 5 per cent, for light Ehine to 18-25 per cent, in sherry and port. These strong wines are usually fortified by addition of spirit. Spirits are liquors distilled from grains, potatoes, beets, rice, etc., that have been mixed with malt and then yeast. Brandy, or cognac, is produced by distillation of wines; rum from fermented cane-molasses; whisky from corn, rye, barley, and potatoes; arrack from fermented rice; pulque from the cactus. Gin is common grain-spirit distilled with juniper ber- ries. Bay-rum is prepared by distilling rum with leaves of myrcia acris and other plants. Spirits contain from 40 to 45 per cent, of alcohol. Dis- tilled, or "raw, spirit" is rectified by charcoal filtration and redistillation to 84 per cent., by weight ("spirit of wine"). The most concentrated alcohol by simple distillation is 91 per cent, by weight, 94 per cent, by volume. Alcoholimetry, the testing of strength of alcohols, is based upon sp. gr. tables. The oily liquid, amyl alcohol (C-H^HO), is the chief in- gredient of fusel oil, a mixture of higher homologs present largely in raw spirit and separated by fractional distillation, C 2 H 5 HO distilling over at a lower temperature. The bad taste and intoxicating effects of poor quality ardent spirits are due, ALCOHOLS. 207 in great measure, to fusel oil. Alcohol containing fusel oil darkens on shaking with H 2 SO 4 . Pyronic aldehyd, or furfurol, is a convulsant poison present in vermouth and bitters. Ab- sinthe contains nine different essences, all toxic. The tertiary isomer of amyl alcohol, amylene hydrate [dimethyl-ethyl-carbinol, (CH 3 ) 2 .COH.C 2 H 5 ] is a colorless, oily liquid, soluble in water and in alcohol, and used as an hypnotic. The higher monatomic alcohols are fatty and waxy solids. Cetyl alcohol, C 16 H 33 HO, is the chief component of spermaceti. Melyssyl alcohol, C 30 H 61 HO, is present in bees-wax. Cholesteric alcohol, C 26 H 43 HO, is the only free alcohol normally present in the human body. It is the principal ingredient of gall- stones. The primary diatomic alcohols, or glycols, are derived from olefins, and are of no practical interest. They are sweet, syrupy liquids. The simplest one is glycol: CH 2 OH CH 2 OH The primary triatomic alcohols, or glycerins, are of great interest and importance. Ordinary glycerin, or propyl hydrate [C 3 H 5 (HO) 3 ] occurs very abundantly in Nature, making up, in conjunction with fatty acids, the bulk of vegetable and ani- mal fats and oils, from which it is liberated by treating with alkalies. It is a by-product in alcoholic fermentation and in the manufacture of soap and stearic acid. The sp. gr. of glyc- erin is 1.25; it boils at 290. It is very hygroscopic, absorbing twice its volume of H 2 0, and thus depleting congested tissues. Glycerin is insoluble except in alcohol and water. It is an ex- cellent solvent for I, Br, starch, carbolic acid, alum, borax, and tannin, such solutions being often termed glycerites. In some respects it is preferable to syrups as a sweetening agent, since it does not ferment. It is also an excellent ex- cipient for fluid extracts. Plasmas are non-fatty ointment sub- stitutes or paints consisting principally of glycerin and water thickened into a gelatinous mass with starch, gelatin, isinglass, and other agents. Most medicated gauzes and cottons contain a small quantity of glycerin or oil and resin to keep them soft and promote the action of the medicinal agents. The "soft gelatin" capsules for liquids contain glycerin. Boroglycerin, C 3 H 5 B0 3 , is made by heating H 3 B0 3 with one and one-half times as much glycerin. It is used as an antiseptic. 208 THE CARBON COMPOUNDS. Experiment. Test for glycerin with borax bead. The green flame is due to free boric acid: C 3 H 5 (HO) 3 + Na 2 B 4 7 H 3 B0 3 + 2NaBO 2 + C 3 H 5 BO 3 On heating glycerin with H 2 S0 4 the characteristic irri- tating odor of acrolein is evolved. Grlycerophosphoric acid is a yellow, syrupy liquid prepared by mixing 1 part of H 3 P0 4 with 1 1 / 2 parts of glycerin, and gradually heating to 190. Both the acid and its salts are used as nervine remedies and to aid nutrition. The hexatomic alcohols mannite, dulcite, and sorbite have the formula C 6 H 12 6 . The first is derived from manna- ash, the second from Madagascar manna, and the third from the berries of the mountain-ash. They resemble sugar in taste, but do not ferment or reduce metallic solutions. ETHERS. Simple ethers are oxids of hydrocarbon radicals; if the radicals are unlike, the ether is termed mixed. A compound ether, or ester, is an oxid of a hydrocarbon radical and an acid radical: in other words, a salt of an acid radical. Ethers are generally formed by the dehydrating action on alcohols of H 2 S0 4 or by combination of other acids with alcohols. The compound ethers have usually a pleasant and refreshing odor. They give the bouquet, or flavor, to alcoholic liquors, where they are generated by age, and they are the chief constituents of fruit-essences, fats and fixed oils, bees-wax (melyssyl palmitate), and spermaceti (cetyl palmitate). Bees-wax (cera flava) is bleached (cera alba) by exposure to light and air or by the use of H 2 2 . It is used in candles. All ethers are neutral. The lower members are volatile liquids; the higher, non-volatile solids. Esters are decomposed by alkalies, which combine with the acid radical, setting free the alcohol. Artificial fruit-flavors consist chiefly of butyrates, acetates, and salicylates of ethyl, methyl, and amyl in glycerin and water. Ordinary ether is ethyl oxid [(C 2 H 5 ) 2 0], sometimes called sulphuric ether because H 2 S0 4 is used in its manufacture. Experiment. Make ether by mixing in a flask 10 c.c. of alcohol, 5 c.c. of H 2 S0 4 , and, after cooling, distilling over the ether at about 140 into a stoppered bottle. Take great care not to bring the vapors into contact with the flame. C 2 H 5 HO + H 2 S0 4 = C 2 H 5 HSO 4 (sulphovinic acid) + H 2 O C 2 H 5 HSO 4 + C 2 H 5 HO= (C 2 H 5 ) 2 O + H 2 S0 4 On a large scale the process is made continuous by allowing alcohol to flow into the flask at the same rate as distillation. The product is puri- ETHERS. 209 fied by mixing with oxid and ehlorid of Ca, pouring off the clear liquid after settling, and distilling. The official ether contains 96 per cent, of (C 2 H 5 ) 2 and 4 per cent, of C 2 H 5 HO. It is a colorless, mobile, and very vola- tile liquid, with characteristic odor, burning taste, and neutral reaction; sp. gr., 0.726; b.p., 37. It is soluble in 10 volumes of H 2 and in alcohol, chloroform, petroleum liquids, and fixed and volatile oils, and is itself a good solvent for fats, fixed oils, and gun-cotton (collodion). It burns readily with a luminous flame, and gives off a combustible vapor. Experiment. Show inflammability of ether by applying a flame to a dram of it in a dish. Note the initial explosion and rapid combustion. Ether is used by inhalation as a general anesthetic, being less depressing, but more irritating, than CHC1 3 . Test for Purity of Ether. Water is detected by turbidity when shaken with an equal volume of CS 2 ; alcohol by shaking with anilin- violet, which colors ether adulterated with alcohol. The spirit and compound spirit of ether consist of about 1 part of ether and 2 parts of alcohol; the latter spirit contains 2 1 / 2 per cent, of ethereal oil, which is a mixture of equal vol- umes of ethyl sulphate (heavy oil of wine) and ether. Acetic ether, C 2 H 5 .C 2 H 3 2 , is a colorless, mobile liquid of a pleasant, acetous, and fruity odor and generally soluble. Experiment. Prepare ethyl acetate by warming alcohol with half as much again each of H 2 S0 4 and NaC 2 H 3 O 2 . Note odor and write equa- tion. Methyl salicylate, CH 3 .C 7 H 5 3 , is identic with oil of betula and the essential constituent of oil of wintergreen. It is pre- pared by distilling a mixture of methyl alcohol, salicylic acid, and H 2 S0 4 . Xitrous ether, C 2 H 5 .N0 2 , is made by distilling a mixture of C 2 H 5 HO, H 2 S0 4 , and NaN0 2 . Sweet spirit of niter contains 4 parts of this ether with 96 of alcohol. Nitroglycerin [C 3 H 5 (N0 3 ) 3 ] is prepared from glycerin and sulphuric and nitric acids. It is a yellow liquid, slightly sol- uble in alcohol; the 1-per-cent. solution is known as spirit of glonoin. Nitroglycerin is very explosive when struck or heated to 257. The products of such an explosion are shown by the following equation: 4C 3 H 5 (N0 3 ) 3 = 12C0 2 + 10H 2 + 6N 2 + 2 These four gases occupy a space about 18,000 times as great as that of the original explosive. When used for this purpose 210 THE CARBON COMPOUNDS. it is generally mixed with some dry, inert powder (charcoal, silica, and sawdust) and sold as dynamite, or giant powder. Amyl nitrite, CgH^NO,,, is prepared in the same way as ethyl nitrite, except that amyl alcohol is used in place of ethyl alcohol. It is a pale-yellow liquid, with the strong, peculiar odor of amyl compounds, and is used by inhalation as a quick stimulant. Amyl acetate, C 5 H 11 C 2 H 3 2 ("essence of pear"), is used by confectioners as a flavoring agent. Salol, or phenyl salicylate, C 6 H 5 .C 7 H 5 3 , is prepared by heating salicylic acid in an atmosphere of C0 2 , whereby it loses H 2 and C0 2 . It occurs in white, faintly aromatic crystals, generally soluble except in water. Taken internally, it is broken up in the duodenum into phenol and salicylate. The same change takes place when salol is combined with caustic hydroxids. Experiment. Dissolve a little salol by warming with liquor po- tassae. Add excess of HC1, and note odor of phenol and ppt. of salicylic acid in silky needles. Salacetol is a substitute for salol, from which it differs by having the radical acetol, C 3 H 5 0, in place of C 6 H 5 . Betol, or #-naphtol salicylate (C 6 H 4 OHCOOC 10 H 7 ), is a white, crystal- line powder used as an intestinal antiseptic. Salophen, or acetyl-para-amido-phenyl salicylate, is an- other derivative of salol in which an atom of H in phenyl is replaced by the univalent group NHCOCH 3 . It is split up by the fat-cleaving ferment of the pancreas into salicylic acid and para-amido-phenol, which is much less toxic than the simple phenol into which salol is partly converted. ALDEHYDS. These compounds are formed, as the name suggests, by dehydrogenation of alcohols, usually by oxidation; for exam- ple, C 2 H 5 HO H 2 = CH 3 COH (ethyl aldehyd). The group COH is characteristic of all aldehyds. They are intermediate between alcohols and acids, and are neutral in reaction. Formaldehyd (methyl aldehyd), HCOH, is obtained by passing air and vapors of CH 3 HO over a heated spiral of Pt or Cu: CH 3 HO + = H.COH + H 2 It is a colorless gas with a pungent odor. A 40-per-cent. solu- tion in H 2 is known as formalin, and is largely used for gen- eral antisepsis in 1 / 4 - to 2-per-cent. solution. Its affinity for ALDEHYDS. 211 H 2 causes it to act as an escharotic in strong solutions, and accounts for its value in sterilizing catgut and hardening ana- tomic specimens. Formaldehyd-vapor is coming into extensive use for disinfecting rooms, either by special apparatus or by hanging up sheets wet with formalin. HCOH does not injure cloth fabrics, but its action is more superficial than that of S0 2 . Paraformaldehyd, (HCOH) 3 , is the triple polymer of for- maldehyd, produced by slow evaporation of the latter in CH 3 - HO. It is a crystalline solid, insoluble in H 2 0. On heating it breaks up into 3 molecules of HCOH, and is very convenient for sterilizing instruments in this way. Acetic, or ethyl, aldehyd, CH 3 .COH, is ordinary aldehyd, obtained from C 2 H r HO by oxidation with K 2 Cr 2 7 in presence of H 2 S0 4 :- 4H 2 S0 4 + K 2 Cr 2 7 + C 2 H 5 HO = CH 3 .COH + Cr 2 (S0 4 ) 3 + K 2 S0 4 + 5H 2 + 2 Experiment. Place in a large flask 2 parts of K 2 Cr 2 O 7 and 6 parts of H 2 0, and then pour in carefully through stop-cock funnel a mixture of equal parts of C 2 H 5 HO and H 2 SO 4 , and warm gently. Note the peculiar fragrance of aldehyd evolved. Now adapt a cork and a long, bent, glass tube and distil slowly into another test-tube. Boil a portion of dis- tillate with KHO and get a brown-yellow, resinous mass. Let the other portion stand for a day or two, when it will be found acid, and, on neutralizing with Na 2 CO 3 , boiling, and adding H 2 SO 4 , the characteristic odor of acetic acid is noted: CH 3 .COH + O = CH 3 .COOH Paraldehyd is the triple polymer of aldehyd, obtained by the action of the ferment emulsin in presence of H 2 0. It is solid, soluble in 8.5 H 2 0, and used as an hypnotic in elixirs. Trichloraldehyd, or chloral, CC1 3 .COH, is a simple substi- tution derivative of aldehyd, prepared by saturating cold alco- hol with Cl (forming chloral alcoholate), then warming to the b.p., and, after cooling and shaking with H 2 S0 4 , distilling the lower liquid layer at 94 to 99. Chloral is a colorless, oily liquid with a sharp odor and acrid taste. Its hydrate, CC1 3 .- COH.H 2 is a valuable hypnotic, obtained by the simple addi- tion of H 2 0. Chloral hydrate appears in white crystals, soluble in all the common solvents. It liquefies when mixed with stearoptens or phenol, and is incompatible with alkalies. Experiment. Heat chloral hydrate with KHO, and note odor of chloroform. Benzaldehyd, C 6 H 5 .COH, is the oil of bitter almond, formed by decomposition of the glucosid amygdalin through 212 THE CARBON COMPOUNDS. the action of the ferment enmlsin in presence of H 2 0. It is a colorless, oily liquid with bitter, burning taste and character- istic aromatic odor. The crude oil contains HCN. Aqua amyg. amarse has 1 part of the oil in 1000 of water. Salicylic, cinnamic, cuminic, anisic, and vanillic aldehyds are derived from the corresponding oils (salicylic from salicin). ACETALS, These compounds are formed by union of alcohol and alde- hyds, with elimination of water. Methylal is a mobile, colorless liquid of aromatic odor, freely miscible with solvents, and used in medicine as an hypnotic. Acetal is similar in physic properties. KETONES, As already stated, these compounds are formed by oxida- tion of secondary alcohols, and are characterized by the group CO 11 . Like the aldehyds, they are neutral and tend to polym- erize, but do not reduce ammoniacal silver solutions as do the former. On oxidation they split into two acids. The only important ketone is acetone, or dimethyl-ketone, (CH 3 ) 2 CO. It is often present in distinct quantity in diabetic urine, and is a product of the distillation of carbohydrates. It is prepared technically by dry distillation of Ca(C 2 H 3 2 ) 2 , the carbonate remaining. It is a liquid of pleasant, minty odor and sharp taste, soluble in water, alcohol, and ether. It gives the iodoform test, the same as alcohol. Its principal uses are as a solvent for resins in varnishes and as a source of CHC1 3 , CHI 3 , sulphonal, and trional. It is also administered internally in 5- to 15-drop doses as an alterative and anthelmintic. Oil of rue is chiefly methyl-nonyl ketone, C 9 H 19 .CH 3 .CO. Hypnone, or acetophenone, is phenyl-methyl ketone, C 6 H 5 .- CH 3 .CO. Chloretone CH 3 I CC1 3 C OH I CH 3 ORGANIC ACIDS. 213 is an hypnotic and local anesthetic formed by adding KHO to equal weights of chloroform and acetone, and distilling with steam. ORGANIC ACIDS. Organic acids are characterized by the fundamental group carboxyl, COOH 1 , replacing H in hydrocarbons. They are monobasic, dibasic, or tribasic according to the number of car- boxyl groups. By replacing H of COOH with metals various salts are formed. The term acid radical signifies the residue of the acid left after subtracting HO. These differ from alkyl or alcohol radicals in containing 0. Acids may be considered hyclroxids of acid radicals, and their anhydrids oxids of acid radicals. The organic acids include both solids and liquids, generally colorless. The variously colored scale compounds are generally solutions of fresh metallic hydrates (Fe particularly) in organic acids or acid salts, said solutions being dried on glass plates. The fatty-acid series of saturated monobasic acids have the general empiric formula C n H 2n 2 . The higher members occur abundantly with glycerin in natural oils and fats and with monatomic alcohols in waxes. Formic acid, H.COOH, occurs in ants (formica rufa), bristles of stinging nettles, and fir-cones, as well as in perspira- tion, urine, and muscle-plasma. In the venom of bees and hornets it is united to C^H^. It may be obtained by heating oxalic acid in presence of glycerin, or by oxidation of methyl alcohol: CH 3 HO -f 2 = H.COOH + H 2 Formic acid is a colorless liquid with sharp odor and irritating action on skin. Experiment. Warm H.COOH gently with a few drops of H 2 SO 4 . The latter acid removes H 2 0, and CO is evolved, as proved by burning; no ppt. with lime-water. Acetic acid, CH 3 .COOH, is found in various plant-juices, partly free and partly combined with K and Ca. It is formed during the decay of many organic substances, and is commonly manufactured by "acetic fermentation" or slow oxidation of weak alcoholic liquors (trickling over wood-shavings in perfo- rated casks) or by the dry distillation of wood. The fermented product is ordinary vinegar, which contains 4 to 10 per cent, of acetic acid. The wood-product, known as pyroligneous acid, is neutralized with milk of lime, the tarry impurities are roasted 214: THE CARBON COMPOUNDS. away, and then, after treating with HC1, the liquid is dis- tilled. Acetic acid is strongly acid, with a distinct vinegar odor. It is a solvent for resins and camphor, and is used largely in manufacturing organic dyes. The glacial acid, so called be- cause it crystallizes below 17, is over 99 per cent, absolute, and is used as a caustic. The official acid contains 36 parts by weight of the acid and 64 of H 2 0; the dilute is of 6-per-cent. Fig. 30. Quick Vinegar Process. strength. It is a curious fact that the highest sp. gr. (1.074) of acetic acid is that of 78-per-cent. strength (acid combined with 1 molecule H 2 0). Dilute acetic acid neutralized with (NH 4 ) 2 C0 3 forms spirit of ammonium acetate: a valuable dia- phoretic. Acetates are neutral and soluble in water, except some basic salts. Experiment. Heat some NaC 2 H 3 O 2 with a drop or two of H 2 SO 4 and note vinegar odor. ORGANIC ACIDS. 215 Carefully neutralize HC 2 H 3 2 and add solution of Fe 2 Cl 6 . A deep-red color results, and on boiling a reddish-brown ppt. Trichloracetic acid, CC1 3 .COOH, is formed by oxidation of chloral with HN0 3 . It is a crystalline caustic and ppts. albu- min. Propionic acid, C 2 H 5 .COOH, is so called because it is the first acid (protos, pion) which can be separated in an oily layer by adding CaCl 2 , etc. It is a liquid with a peculiar odor, and is present in sweat and urine. Butyric acid, C 3 H 7 .COOH, is the characteristic acid of butter, where it exists free when rancid, as also in feces and sweat. It is a liquid, differing from higher, common, fat acids in being soluble in H 2 0. Of the two valeric, or valerianic, acids, C 4 H 9 .COOH, the 150 is the more important. It has the odor of valerian, and is found in this root and angelica. It is also a product of albu- minous decomposition; hence is present in old cheese and hu- man excrement. It is usually obtained by oxidation of amyl alcohol. It is an oily, colorless liquid, and is soluble in alcohol. Caproic acid, C 5 H 1:L .COOH, is present in goat-butter; myristic, C 14 H 28 2 , in nutmegs and cocoa-nuts; and caprylic in Limburger cheese and cocoa-nut oil. Enanthylic acid, C 7 H 14 2 , is present in oxidized castor-oil, and has an agreeable odor. Pelargonic acid, C 9 H 18 2 , is found in geranium-leaves; lauric, C 12 H 24 2 , in cocoa-nut oil; arachidic, C 20 H 40 2? in pea- nuts; bycenic, C 22 H 44 2 , in oil of ben; cerotic, C 27 H 54 2 , in small grains free in bees-wax; and melissic, C 30 H 60 2 , in bees- wax. True cerates always contain wax. The soap-like decom- position that dead bodies sometimes undergo is due to forma- tion of adipocere, the NH 4 and Ca salts of cerotic acid. Stearin candles are a mixture of palmitic (HC 16 H 31 2 ) and stearic (HC 1R H 35 2 ) acids, both white, smooth solids. Of the unsaturated, monobasic acids of the olefin series, oleic, C 17 H 33 .COOH, is most important. It is a constituent of fixed oils, and a by-product in the manufacture of candles. It is a colorless, oily liquid; tasteless, neutral (unless exposed to air); sp. gr., 0.9; insoluble in H 2 only (oleates of K and Na dissolve in H 2 0). HN0 2 changes oleic acid to crystalline elai- din, and it solidifies spontaneously below 15. It forms oleates with metallic oxids and alkaloids. Eicinoleic acid is an isomer of oleic. Angelic acid is in the root of the same name. Erucic acid is present in oil of mustard. Diatomic acids have the general composition C n H 2n 3 and may be considered diatomic alcohols in which one HO is re- placed by COOII. 216 THE CARBON COMPOUNDS. Glycolic acid, CH 2 .OH.COOH, is a white, crystalline solid found in unripe grapes and leaves of the wild grape. Lactic acid, C 2 H 4 OH.COOH, is present in opium, ensilage, sauer kraut, gastric juice, and the gray matter of brain. It is produced by lactic fermentation of sugar (sour milk, koumiss, kefir). The official acid is 75-per-cent. strength. It is a color- less, odorless, syrupy liquid; sp. gr., 1.2; generally soluble. Sarcolactic, or paralactic, acid is found in muscles (more after work), extract of beef, blood, and sometimes urine. It differs from ordinary lactic acid only in its action on polarized light. Identification of Lactic Acid. A few drops of acid added to very weak solution of Fe 2 Cl 6 gives a distinct yellow color. Oxalic acid [H 2 C 2 4 .2H 2 0(COOH.COOH)] is found in many plants, as dock and wood-sorrel (Oxalis acetosella) in the form of the K salt; in rhubarb, beets, etc., as the Ca salt. It is prepared artificially by oxidizing starch or sugar with HN0 3 , or by fusing cellulose (sawdust) with caustic K or Na. It is a white, very sour, crystalline, poisonous solid, freely soluble in water, less so in alcohol. It is used as a mordant in calico- printing, to clean Cu, as a solvent for Fe stains, and a precipi- tant for Au and Pt. The Ca salt is very insoluble, and often gives rise to urinary calculi. Experiment. Make ink by mixing clear, aqueous solutions of tannin and FeS0 4j and decolorize with clear solution of H 2 C 2 4 . Succinic acid, H 2 C 4 H 4 4 , occurs in amber (succinum), lig- nite, and unripe grapes. It appears in colorless prisms with acrid taste, more soluble in water than in alcohol. It is seda- tive and diuretic. Malic acid, H 2 C 4 H 4 5 (oxysuccinic), is widely distributed in the vegetable kingdom in unripe grapes, apples, quinces, currants, gooseberries, rhubarb, etc. It appears in hygroscopic needles. The laxative effect of fresh cider is due to malic acid. Tartaric acid, H 2 C 4 H 4 6 , occurs in four isomeric forms, namely: meso-, levo-, and dextro- tartaric and racemic (para- tartaric) acids. The common dextro-acid is obtained from grape-juice, where it is both free and in combination with K and Ca. The pure acid appears in colorless, monoclinic prisms of acid taste, soluble in H 2 and alcohol. On strongly heating, it chars quickly, giving off a distinct caramel odor. It is used in calico-printing and by confectioners to prevent crystallization of sugar. Identification of Tartaric Acid. Neutral solutions give a white ppt. with CaCl 2 , soluble (after quickly collecting on filter and washing) in KHO, but pptd. on boiling. ORGANIC ACIDS. 217 The basis of granular effervescent salts is a mixture of NaHC0 3 (83 to 85 parts) with a slight excess of citric (70) or tartaric (75 parts) acid and sugar. They are combined by heat- ing a little above b.p. or by moistening and stirring mixed pow- ders with alcohol, making the granules even by sifting after drying. Ninety grains of the finished salt equal a teaspoonful. The tribasic acid, citric, H 3 C 6 H 5 7 , occurs free in lemons (6 per cent.), currants, cranberries, raspberries, and gooseber- ries. The Ca salt is present in wood, potatoes, and beets. The acid appears in large, colorless crystals, readily soluble in H 2 0. Of the aromatic acids, benzoic and salicylic are most im- portant. They are both sublime substances, antiseptics, and preservatives, Benzoic acid, HC 7 H 5 2 (C 6 H 5 .COOH), occurs in gum benzoin and the urine of herbivora. It is manufactured from toluene by treating with Cl, then H 2 0. It appears in large needles, sparingly soluble in cold water, but freely soluble in alcohol. Identification of Benzoic Acid. After neutralizing, Fe 2 Cl c gives a flesh-colored or reddish ppt. Salicylic or oxybenzoic acid, HC 7 H 5 3 (C 6 H 4 .OH.COOH), is present in oil of wintergreen and coal-tar. Experiment. To some oil of wintergreen add five times as much liquor potassae, and heat until completely saponified. Now add HC1 and note ppt. of crystals of salicylic acid. It is usually prepared synthetically by treating phenol with NaHO, and then the resulting NaC 6 H 5 with C0 2 ; then heat- ing without air to convert isomeric NaC 6 H 5 C0 3 into NaC 7 H 5 3 ; and finally treating with HC1 to liberate the acid. Salicylic acid appears in fine needles of a sweet taste, sternutatory, and of acid reaction, soluble in 2.5 alcohol or 450 H 2 0. Identification. Salicylic acid, even in very dilute solutions, gives a violet color with ferric salts. Cinnamic acid, C 6 H 5 .CHCH.COOH, occurs in storax and balsams of Peru and Tolu, to which it imparts the fragrant odor. Official or gallotannic acid, HC 14 H 9 9 , obtained by extract- ing nut-galls with ether and alcohol and evaporating solution, is a light-yellow, scaly compound; bitter, slightly acid, and strongly astringent; readily soluble in water and dilute alcohol. There are quite a number of closely related tannins (oak-bark, nut-galls, coffee, tea, etc.). These all ppt. albumin and gelatin, tartar emetic, and most alkaloids, and form non-putrefying combinations with animal compounds, on which fact the process 218 THE CARBON COMPOUNDS. of tanning depends. They produce black or blue-black ink with Fe salts, and hence are incompatible with these. A few vege- table bitters namely: columbo, quassia, chiretta, and gentian contain no tannin and may be prescribed with Fe solutions. Experiment. Note color of ppt. formed by solutions of tannic acid and lime-water; tannin and Fe 2 Cl 6 ; tannin and KHO. Gallic acid, HC 7 H 5 5 [C 6 H 2 (OH) 3 .COOH], is made by fermenting nut-galls or tannin: It occurs in long needles, more soluble in alcohol than in water, and gives a blue-black ppt. with ferric salts, but does not coagulate albumin or ppt. gelatin or alkaloids. It is preferred to tannin for internal administration, since the latter must first be hydrolyzed into gallic acid before it can be absorbed. Experiment. Add a fragment of KCN to solution of gallic acid, and notice deep-rosy color. Phthalic acid [C 6 H 4 (COOH) 2 ] is a dibasic acid used as a source of the indicator phenol-phthalein. The relations of the various series of organic acids are shown by the following general formulas: Acetic: Hydroxacetic, or lactic: C n H 2n OHCOOH. Dihydroxacetic, or glyoxylic: C n H 2n _ 1 (OH) 2 COOH. Succinic: CJE^(OOOH),. Hydroxysuccinic, or malic: C n H 2n _ 1 OH(COOH) 2 . Dihydroxysuccinic, or tartaric: Citric acid is expressed: C 3 H 4 OH(COOH) 3 ; that is, hydroxy-pro- pane-tricarboxylic acid. Hydrocyanic, or prussic, acid, HCN, is a colorless liquid with an odor like that of peach-blossoms; it changes to a gas at 26.5. It is produced spontaneously by decomposition of amygdalin, a substance present in bitter cassava, cherry-laurel, wild cherry, bitter almonds, and the pits of stone-fruit. The United States Pharmacopeia preparation is a 2-per-cent. aque- ous solution of the acid; the dose of this preparation is from 1 to 5 m. It is slightly acid, but very poisonous. AgN0 3 gives a white ppt. of AgCN, not darkening in the light. When AgCN is heated, cyanogen, ON, is liberated. It burns with a flame the color of peach-blossoms. FATS AND FIXED OILS. 219 FATS AND FIXED OILS. These are esters of glyceryl and the higher fatty acids, and are often termed glycerids. They are, for the most part, mixt- ures of triolein [C 3 H 5 (C 18 H 33 2 ) 3 ], tripalmitin [C 3 H 5 (C 16 H 31 - 2 ) 3 ], and tristearin [C,H B (C 18 H 85 2 ) 8 ]. The first is a liquid and the chief constituent of oils; the second, semisolid; the third, a hard solid. In plants they are found chiefly in seeds and nuts; in animals under the skin and upon the viscera and muscles. Human fat is 67 to 80 per cent, olein. They are usually obtained by expression or melting. So-called margarin is a mixture of palmitin and stearin. Pure fats are colorless, odorless, and tasteless. They leave a permanent translucent stain on paper. They differ from mineral oils in containing 0, the proportion of which is low as compared with C. They are insoluble in water and nearly so in cold alcohol (except castor-oil and croton-oil), but are readily dissolved by ether, chloroform, gasolin, benzin, benzene, CS 2 , etc. Fats and oils are emulsified by soap, acacia, or albumins. Solid fats melt below 100 and can be distilled without chemic change at about 300, but are decomposed at higher tempera- tures into a number of products, of which the offensive smell- ing aldehyd acrolein, C 3 H 4 (from glycerin), is most distinctive. Ordinary fats, containing albuminous matter, tend to become yellow and rancid, after a time, by liberation of fatty acids. Drying or siccative oils (linseed, for example) are so called be- cause they contain unsaturated acids, and harden by taking up 0. Albuminous impurities, which prevent this oxidation, are removed by treating with 4 per cent, of H 2 S0 4 and decanting the refined oil. Fats and oils burn readily, giving off a large amount of heat. When fats or oils are treated with alkaline hydroxids, glycerin is set free and a soap is formed, the process being termed saponification. When treated with ferments or superheated steam or boiling acidulated water, hydration takes place with formation of glycerin and a fatty acid. Fats and oils are used as foods and medicines and in paints and varnishes. The purest olive-oil has a greenish tinge. On cooling to near f.p. it separates into crystalline palmitin and fluid olein. Cotton-seed oil is pale yellow, and is used largely as an adul- terant and substitute for olive-oil, butter, and lard, as are also pea-nut (earth-nut, arachis) and sesame (teel, benne) oils. Oil of almond is usually straw-colored and should have no odor of bitter almonds. Codliver-oil is quite complex. In addition to the fats, jecolein, palmitin, stearin, myristin, and therapin, it contains a little cholesterin and gaduic acid, gadium, the alka- 220 THE CARBON COMPOUNDS. loids asselin and morrhuin, traces of I and Br, and various amins. It saponifies very readily, and hence is easy of diges- tion. The inferior grades are dark in color. Linseed- or flaxseed- oil is about 80 per cent, linolein [C 3 H 5 (C 18 H 31 2 ) 3 ]. Being unsaturated, it absorbs and be- comes gummy. The same glycerid is present in walnut, hemp- seed, sunflower, poppy-seed, and niger-seed oils. The drying effect is much increased by boiling the raw oil in a current of air, sometimes adding oxid of Pb, Fe, or Mn, or borates. Lin- seed-oil is used in paints and printers' ink. The latter is a boiled linseed varnish containing lamp-black or some other color and a little soap. Drying oils may, by absorbing 0, cause sufficient heat to ignite rags or clothing soaked therewith. Fig. 31. Lard, Crystallized from Chloroform. Castor-beans are nearly one-half oleum ricini, which is noted for its viscosity and nauseous taste. Besides the three usual glycerids, it contains ricinolein [C 3 H 5 (C 18 H 33 2 ) 3 ] ; an alkaloid, ricinin; and an albumose, ricin. Five-per-cent. castor- oil in petrolatum increases its absorptive power for H 2 four- fold (10 parts). Croton-oil contains a peculiar principle, cro- tonol, which excites a pustular eruption when applied to the skin. Croton-oil is a very energetic drastic cathartic. Lard-oil is "cold pressed": that is, extracted from lard at a low temperature. It is used in cooking. Benzoinated lard contains 2 per cent, benzoin, which retards rancidity. Experiment. Dissolve some lard in warm alcohol. Examine with microscope the crystals that form on cooling. FATS AND FIXED OILS. 221 Butter contains, in addition to 92 per cent, of olein, pal- mitin, stearin, myristin, and arachidin, the glycerids of butyric (7 per cent.), capric, caprcic, and caprylic acids, which charac- teristic acids are volatile and soluble in water: a fact that is made use of in testing butter for adulteration. Butter contains, as a rule, 15 to 20 per cent, of water. The presence of butter- milk causes butter to decompose very rapidly. Test for Butter. Put a little in a test-tube and add two or three times as much alcoholic potash solution, and warm in the steam- or water- bath. Now add a few drops of H 2 SO 4 , and notice pine-apple odor of butyric ether. Oleomargarin is a butter substitute prepared from the fat of omentum and mesentery of beef-cattle. This fat is hashed Fig. 32. Human Fat, Crystallized from Chloroform. fine and then melted at about 50. The liquid fat thus pro- cured is kept in small vats at 27 for two or three days, to allow crystallization of the harder fats. From these yellow oleo-oil is obtained by pressure, and is churned with milk, col- ored, and rapidly chilled. Butterine has lard added to oleo- oil and milk before churning. Palm-oil is brown or reddish yellow and is between lard and tallow in consistence. Cacao-butter (oleum theobromatis) is a light-yellow, brittle solid with a pleasant odor, melting a few degrees below the temperature of the body. It is used extensively as a basis for suppositories. A drop of glycerin added to each suppository (cold process) renders it more cohe- sive. 222 THE CARBON COMPOUNDS. The elaidin test for oils consists in shaking with nitrous acid, when, if positive, white, solid elaidins are formed. Olive-, almond-, ben-, mustard-, rape-seed, earth-nut, bone-, lard-, neat's-foot, tallow-, sperm-, doegling-, and dolphin- oils all react to this test. Lanolin, or wool-fat, is an ester of the cholesterins, C 26 - H 43 HO. It is light yellow in color and has the odor of sheep's wool. It differs from ordinary fats in being miscible with twice its weight of H 2 0, and it is also quite a stable product. The official hydrous lanolin contains not more than 30 per cent, of H 2 0. Lanolin is very similar to human sebum. It is especially good for incorporating liquids in ointments. Any stickiness is overcome by adding a small proportion of liquid petrolatum. Lecithins, or phosphorized fats, are found in nearly all cells, being most abundant in the brain and nerves, white blood- corpuscles and yelk of eggs (25 per cent, of vitellin). The one most frequent in the animal body has the empiric formula C 44 H 90 NP0 9 . Lecithin is soft and waxy, forming with H 2 a pasty mass, which under the microscope exhibits the "myelin" oily drops and threads. On decomposition lecithin yields H 3 P0 4 , some fatty acid (oleic, palmitic, or stearic), and an organic base, cholin. SOAPS. Soaps are fatty-acid salts of various metals, generally ob- tained by boiling an hydroxid or oxid with a fat or oil: lard, tallow, olive, cotton-seed, palm, pea-nut, etc. Soft soap is a K compound; hard soap contains Na. The oil, the fatty acid, or the alkali may be in excess. Experiment. To 10 c.c. of olive-oil add one-fifth as much 10-per- cent. KHO. Boil and stir until mixture is homogeneous and no oil separates when a little is poured into water, keeping up original volume by adding H 2 O. The resulting soft soap is converted into hard soap by adding saturated solution of NaCl and allowing to cool. C 3 H 5 (C 18 H 33 2 ) 3 + 3KHO = 3KC 18 H 33 O 2 + CH B (HO) 8 KC 18 H 33 2 + NaCl = NaC 18 H 33 2 + KC1 K, Na, and NH 4 soaps are soluble in H 2 and alcohol, but are thrown down by saturating with a neutral salt, as shown by the curd formed on adding common salt; all others are in- soluble. Soaps are decomposed by mineral acids, which set free fatty acids, forming new salts. Transparent toilet soaps are made with castor-oil. Lard soaps are white and hard and often float on water. Glycerin is present in all soaps made by re- action between fats and alkalies; it is absent from soaps made FATS AND FIXED OILS. 223 with free fatty acids liberated by superheated steam. The com- mon yellow soap is prepared with tallow- or palm- oil and soda, and often also some rosin. Palm and cocoa-nut soaps dissolve in salt-water, and are much used at sea. Cocoa-nut oil is often added to a soap to make a good lather. Various coloring, odorous, medicinal, and polishing agents (sand, emery) are fre- quently added to soaps for special purposes. All soaps contain H 2 (from 20 to 80 per cent.), with which the smoothness varies. Soaps cleanse by union in excess of H 2 of their freed alkali with the greasy dirt on the surface of the skin, the in- soluble salt forming a slippery lather. When used in hard Fig. 33. Soap Coppers. waters insoluble Ca and Mg soaps are first pptd. before there is any detergent action on the skin. Soap-suds are due to reaction between the alkali and the acid salt formed by the soap decomposing on dissolving. The official soap is white Castile, a Na soap made from olive-oil. The mottled appearance of some Castile soaps is due to FeS0 4 . Ammonia liniment and lime liniment are fluid soaps prepared by mixing cotton-seed- oil with NH 4 HO (also 5-per- cent, alcohol) and linseed-oil with lime-water. Green soap (sapo viridis) is usually brown in color. It is a jelly-like potash soap made by adding indigo to ordinary soft soap. Lead plaster is chiefly lead oleate, and is prepared by boiling PbO with twice 224: THE CARBON COMPOUNDS. as much olive-oil and one-third as much H 2 for several hours. It is a pliable, tenacious mass, insoluble in water. It is the basis of a number of official plasters. Ungt. diachylon has 60 parts of lead plaster, 39 of olive-oil, and 1 part of oil of lav- ender. In fusing for ointments and plasters the body having the highest m.p. should be melted first, then the others in order, stirring in any insoluble powder, while cooling. CARBOHYDRATES. Carbohydrates are compounds of C, H, and 0, the two latter elements in the same proportion as in water, the C gen- erally in 6's or some multiple thereof. They are derived by oxidation of hexatomic alcohols, and are in composition mostly penta-oxyaldehyds [COH.(CHOH) 4 .CH 2 OH dextrose] and penta-oxyketones [CH 2 OH.(HCOH) 3 .CO.CH 2 OH = levulose], or anhydrids of these. Some unimportant carbohydrates con- tain from 3 to 9 atoms of C. Carbohydrates make up the greater bulk of plant-tissues; much less abundant in animals. With the aid of sunlight and chlorophyl plants build up formaldehyd, then sugar, then starch, cellulose, and proteins from the waste-products of ani- mals. The mineral salts are similar in both plants and animals. The following equations represent a few synthetic results, with- out representing the complex intermediate steps: A hydrocarbon: 10C0 2 + 8H 2 O C 10 H ]6 + 28O. A carbohydrate: 6CO 2 + 6H 2 O = C 6 H 12 O 6 + 120. An organic acid: 2C0 2 + H 2 = H 2 C 2 O 4 + 0. A nitrogenous compound : 10C0 2 + 4H 2 + 2NH 3 = C 10 H 14 N 2 + 24O. Carbohydrates are mostly white and solid. All have a neutral reaction. They are generally soluble in H 2 0, difficultly soluble in absolute alcohol, and insoluble in ether. Some are crystalline; others, more complex, are colloid. They sometimes form loose chemic combinations with bases. Unchanged or after treatment, they have a sweet taste, a reducing action on certain metals (Cu, Bi, etc.), and power to rotate polarized light and undergo alcoholic fermentation. They are readily oxidized in alkaline solutions, turning yellow or dark brown on heating. According to their structure, carbohydrates are divided into three classes, the members of any one of which may be converted into those of another class by hydrolysis or dehydra- tion : CARBOHYDRATES. 225 Polysaccharids (amy- loses or amyloids) Cellulose (cellulin). Lignin. Tunicin (animal cellulose ascidians and cyn- thians). Starch (amylum or glucosin-). (C 6 H 10 O 5 ) n (6 to 200). Mostly I Dextrins (British gum). colloid. Disaccharids ( bioses or saccharoses) : C 12 H 22 O 17 . Crystalline and dif- fusible. Inulin (levulin rotates ray to left). G lycogen ( liver-starch ) . Raffinose and lactosin (crystalloid). Gums. Sucrose (cane, beet, sorghum, maple, palm, sweet fruits). Lactose (milk-sugar, C 12 H 22 O n .H 2 O). Maltose (malt-sugar). Isomaltose (sweet extracts, amorphous). f Dextrose (grape-sugar, glucose). j Levulose (fructose, formose, diabetin). simple sugars): C 6 H 12 O 6 . Crystalloid. I n (teluscle . sn g ar . also derived from hex- amethylene, C 6 H I2 ). General Test. Molisch's Reaction. To a few c.c. of dilute syrup add a few drops of 15-per-cent. alcoholic solution of a-naphtol, and then add very slowly twice as much by volume of H 2 SO 4 as of the sugar solu- tion, sliding it down the side of the inclined tube. Note reddish-violet ring of furfurol. Cellulose, or plant-fiber, forms the cell-walls, or frame- work, of plants, and is the pulp, or indigestible part, of fruit. The trunks of trees contain also 6 or 7 per cent, of mineral matter. Pure cellulose is prepared by grating vegetable tissue (flax,, cotton, hemp, wood, pith) and washing away the starch. Absorbent cotton and filter-paper are nearly pure cellulose. It is soluble in ammoniated CuS0 4 (from which it is pptd. as a white mass by acids) and in strong mineral acids, which con- vert it into dextrin. The fine, flexible, elastic fibers of cellulose are pressed or woven into linen, muslin, thread, ropes, paper (wood-pulp heated with CaS0 3 under pressure), and papier- mache. When treated with H 2 S0 4 , cellulose is partly changed into a jelly-like glaze of hydrocellulose, or amyloid. Unsized paper dipped first into H 2 S0 4 (4 volumes to 1 of H 2 0), and then immediately washed and dried, is converted into smooth, tough parchment-paper. Experiment. Prepare parchment-paper in the manner mentioned, and show that it yields blue amyloid reaction with H 2 SO 4 and I. 226 THE CARBON COMPOUNDS. The nitrocelluloses are important explosive and combus- tible compounds prepared by treating cotton or paper with HN0 3 and H 2 S0 4 . Gun-cotton is the trinitrate [C 6 H 7 2 - (N0 3 ) 3 ]. Pyroxylin is the dinitrate [C 6 H 8 8 (N0 8 ) 2 ]. The styptic fluid collodion is a solution of trinitrate and tetranitrate in alcohol and ether. Wood-silk is a mixture of cellulose and nitrocellulose. Celluloid is a smooth material prepared by in- corporating pyroxylin with camphor and sometimes ZnO or vermilion. Xylonite is a similar pyroxylin compound. Smoke- less gunpowder is gun-cotton gelatinized with acetone or acetic ether and then dried and granulated; or gun-cotton mixed with nitrate of K and Ba; or gun-cotton combined with nitroglyc- erin; or picric acid; or nitronaphthalens. On destructive dis- tillation cellulose yields CH 3 HO, creasote, C 2 H 4 2 , etc. Lignin is very similar to cellulose, and forms the inner lining of woody cells and vessels. Starch is present in all parts of plants, especially the seeds, roots, and tubers, where it serves as a food-supply for the young plant. Rice contains 77 per cent, of starch; potatoes, 21; sago, 90; cereals, 50 to 70 per cent. It occurs in small grains in the cellulose cells, each kind having a different microscopic appear- ance according to its origin, 0.002 to 0.020 in diameter, and concentric arrangement around nucleus. The starch is sepa- rated by grating, washing, and decanting. It is white, taste- less, amorphous, and slippery to the touch. It is insoluble in cold water. Hot water, alkalies, or ferments loosen the outer insoluble husk (farinose) and set free soluble granulose. Acids, heat, and ferments break starch down into dextrins, then iso- maltose, maltose, and dextrose. The conversion of starch into sugar by the action of dilute H 2 S0 4 is an hydrolytic process, and is explained by the fact that H 2 S0 4 diluted with H 2 forms orthosulphuric acid (H 2 S0 4 .2H 2 0), which, with the aid of heat, gives up the H 2 to the starch in the nascent state, as it were. Starches are much used as food, in the manufacture of alcohol and glucose, and for stiffening paper and linen. Experiment. Change starch to sugar by boiling with a little H 2 O and a drop of H 2 SO 4 . Note change in taste. Test for Starch. I gives a purple color to wet starch; brown, to dry. This color, due to C 6 H 9 IO 5 I, disappears on heating, and is partly restored on cooling. The color is likewise destroyed by adding anything which will form a compound with I, as Ag salts, alkaline hydrates, and sodium thiosulphate. Dextrin is intermediate between starch and glucose or maltose. It is a light-yellow, amorphous powder, quite soluble in H 2 0, less so in alcohol. It rotates a ray of polarized light PLATE I. r*3 Y'.JA ***-- fcrjpJL C$tJ STARCHES. (From Bartley's "Medical and Pharmaceutical Chemistry.") i. Potato Starch. 2. Bermuda Arrowroot. 3. Tous les Mois. 4. St. Vincent Arrowroot. 5. Sago of Commerce. 6. Port Natal Arrowroot. 7. Rio Arrowroot. 8. Tapioca. 9. Maize. CARBOHYDRATES. 227 to the right. Amylodextrin (C 30 H 50 25 ) gives a blue color with I; erythrodextrin, a reddish-brown color; achrob'dextrin and maltodextrin give no color, but reduce Cu solutions slightly. Dextrin is manufactured on a large scale by heating starch for a short time at 160 to 250. Dextrins are used as toast, bread- crust, infant-foods, mucilage, and book-binders' paste, and in dyeing, calico-printing, postage stamps, finishing, and glazing of cards and wall-paper. Glycogen, or liver-dextrin, imparts a sweet taste to this organ, the carbohydrate reservoir, and is present largely in mus- cular tissues and oysters. It is a white, amorphous powder, pptd. by alcohol and given a port-wine color by I. It is non- dialyzable. Gums are amorphous, odorless, tasteless, viscid, translucent substances obtained as vegetable exudations, or extracted by alkalies and pptd. by HC1 and alcohol. Gum arabic, or acacia, is the chief Ca salt of arabic acid, C 12 H 22 11 ; it is acid in re- action, and is the leading emulsifier in pharmacy. Other com- mon gums are carrhageen (Irish moss), lichenin (Iceland moss), bassorin (tragacanth), cerasin (cherry-tree gum), marshmallow, flaxseed, and Senegal. They form sticky mucilages with H 2 0. Heating with HC1 changes them to dextrose in part. They yield mucic acid when oxidized by HN0 3 . Pectin, or vegetable jelly, constitutes the greater portion of Irish and Ceylon moss, and is the substance that causes vegetable juices to gelatinize. Gums are used in medicine as demulcents. Sucrose is obtained chiefly from cane and beets by crush- ing, then coagulating vegetable albumin by boiling with 1-per- cent, milk of lime, treating with C0 2 , skimming, boiling with animal charcoal, filtering, and crystallizing in vacuum appa- ratus, the crystals being separated by centrifugation. The sugar remaining in molasses can be extracted by adding Sr(HO) 2 and passing in C0 2 to ppt. SrC0 3 . Saccharose is sweet, and appears in large monoclinic crystals; sp. gr., 1.6; very soluble in H 2 (0.5 cold); insoluble in strong alcohol, ether, or chloroform. It is inverted i.e., converted into dextrose and levulose by boiling, acids, or ferment action; even strongly acid fruit-juices have power to invert sucrose. + 66.5 +52.5 -94.4 C 12 H 2 Ai + H 2 = C 6 H 12 6 + C 6 H 12 6 Cane-sugar melts at 160 and cools into clear, glassy barley-sugar. At higher temperatures it turns yellow, forming dextrose and a gummy substance called levulosan. On heating 228 THE CARBON COMPOUNDS. still further (200) it gives off gases and darkens into brown caramel from loss of H 2 0, being finally reduced to one-third its volume of coke. H 2 S0 4 also chars cane-, but not grape- or milk- sugar. Cane-sugar does not undergo alcoholic fermenta- Fig. 34. Vacuum Pan. tion, except indirectly through invertase, and does not respond to the copper tests. It forms insoluble sucrates or saccharosates with Ca, Ba, and Sr hydrates. It is used in food, syrups, pre- serves, and wines. Caramel is employed to color liquors, vine- gars, confectionery, etc. CARBOHYDRATES. 229 Experiment. Change cane-sugar to glucose by dissolving a few grains in H 2 O, adding a drop of H.,SO 4 , and boiling ten or fifteen minutes. Prove that this product reduces alkaline CuSO 4 solution, changing the color from blue to yellow, then red, whereas cane-sugar solution has no such reducing effect. Lactose constitutes 3 to 7 per cent, of milk, and is a by- product in the manufacture of cheese, the whey being evapo- rated and the sugar collected on strings and sticks. It is slightly sweet; sp. gr., 1.5; soluble in 6 parts of water. It undergoes lactic and alcoholic fermentation (with ordinary, not pure, yeast) and responds to the glucose reduction tests. Dilute acids convert it into galactose and dextrose. Owing to its hard- ness and grittiness, it is widely utilized in powders and tablet triturates. Maltose is obtained from starch by diastatic fermentation, or by boiling with dilute H 2 S0 4 . The same change takes place spontaneously during the germination of seeds. It appears in white needles soluble in both water and alcohol. On hydrol- ysis it breaks up into two molecules of dextrose. It ferments with yeast to alcohol and responds to the glucose reactions. Maltose and lactose are distinguished from glucose by not re- ducing Barfoed's reagent (solution of cupric acetate in acetic acid). Dextrose makes up 10 to 50 per cent, of grape-juice, and is widely distributed in vegetables (raisins, figs, and other sweet fruits) and honey, usually with an equal amount of levulose, the mixture being known as invert-sugar. It is the form in which carbohydrates are absorbed into the blood, and is present in diabetic urine. It is manufactured on a large scale by heat- ing starch or cellulose with dilute acids, excess of acid being removed with chalk. It is crystalline (small cubes or square plates) if anhydrous; it is only half as sweet as sucrose, and soluble in its own weight of water and in dilute alcohol. With yeast it ferments to alcohol and C0 2 , and also may undergo lactic-acid (in presence of milk or cheese) or butyric-acid fer- mentation. C 6 H 12 6 = 2C 3 H 6 3 2C 3 H 6 3 = C 4 H 8 2 + 2C0 2 + 2H 2 By oxidation it is changed to saccharic or oxalic acid. It is a strong reducing agent (1 molecule = 5CuO). It aids the solu- tion of lime in water. It is used in food as syrups and in pre- serves, confectionery, and artificial honey; also in printers' rollers and copying inks. Experiment. Show reducing action of dextrose on an alkaline aqueous mixture of some Bi salt. Note the change from white to gray or black. #30 THE CARBON COMPOUNDS. Levulose occurs with dextrose as invert- or fruit- sugar. The purest is obtained from inulin. It appears as needle-shaped crystals or a thick syrup, which prevents dextrose from crystal- lizing. It responds to the dextrose test with two-thirds as much reducing power. Both dextrose and levulose can be prepared synthetically (acrose) from HCOH by treating with milk of lime. It is used as a substitute for cane-sugar in diabetes. Galactose is obtained from lactose or gums by hydrolysis, and is present in koumiss and kefir. It does not ferment with yeast, but reduces Cu solutions. On oxidation it is changed into mucic acid. Many unimportant compounds are produced by the oxi- dation of hexatomic alcohols. Rhamnose has the formula C 6 H 12 5 ; glycerose, C 3 H 6 3 ; erythrose, C 4 H 8 4 ; mannose (from mannite), C 6 H 14 6 . Pentosanes are plant-products yielding pentoses by hydration. Inulin, from elecampane, is an ex- ample; arabinose, C 5 H 10 5 , is another. Scyllite is a sugar ob- tained from fishes. Bioses and trioses are composed of 2 or 3 molecules of glucose with H 2 0. On heating invert-sugar with dilute mineral acids it yields levulinic acid, C 5 H 8 3 , and humous substances. GLUCOSIDS, OR COMPOUND SUGARS. The glucosids are compound ethers which, under the in- fluence of ferments or dilute acids or alkalies, take up H 2 and split into glucose and other products. They are generally neu- tral, soluble (except in ether), and crystalline. Many are optic- ally active (levorotatory). Some contain N. They are usually of vegetable origin (often accompanied by a ferment) and are extracted with water or alcohol, decolorized with animal char- coal and crystallized. They can be made synthetically from glucoses dissolved in alcohol, into which HC1 gas is passed. They are incompatible with free acids, alkalies, or ferments. Their names nearly all end in in (Latin, inum), exceptionally in etin, egol, or idin. Below is a list of the most important glucosids: Absinthin. Bitter principle of wormwood. Absinthe is sweetened dilute alcohol flavored with oil of wormwood and colored with chlorophyl. Adonidin. Adonis vernalis; cardiac tonic. Amygdalin (C^H^NOn). White, crystalline powder; bitter almond, cherry-laurel, etc.; dilute acids convert into dextrose, benzoic aldehyd, and HCN; same change spontaneous in aqueous extracts, owing to action of ferment emulsin. GLUCOSIDS. 231 Arbutin. Uva ursi; bitter. Baptisin. Baptisia tinctoria; purgative. Bryonin. Bryonia-root; hydragog. Cathartic Acid. Senna. Cerebrin. Brain- and nerve- tissue; yields galactose or cerebrose. Chitin. Shells of crustacese. Colocynthin. Colocynth-f ruit ; purgative. Coloring Principles. See "Indican," "Carminic" and "Ru- berythric Acids," and "Xanthorhamnin." Coniferin. Woody tissue of sugar-cane and cambial juice of conifers; yields vanillin with O0 3 . Convallamarin. Convallaria ; heart-tonic. Convolvulin. Jalap; drastic purgative. Cotoin. Active principle of coto. Digitalin (C 5 H 8 2 ). White, amorphous, bitter substance from leaves of fox-glove; soluble in 1000 H 2 or 100 dilute alcohol; yellow solution with HC1. Other digitalis principles are digitonin (amorphous, yellow, soluble in alcohol), digitoxin (colorless, crystalline, very poisonous, not a glucosid), and digitalein (white, amorphous, very bitter). Boiling with dilute acids yields resinous substances. Identification of Digitalin. Solution in H 2 S0 4 is yellow, gradually turning blood-red, or changing to violet on adding a drop of HNO 3 or Fe 2 Cl c solution. Esculm. Bark of horse-chestnut. Fraxin. Ash-bark. Gentiopicrin. Gentian-root. Glycyrrhizin. Licorice-root; quinin and acids incom- patible form resinoid bitter and sugar, like glucose. Helleborin and Helleborein. Black and green hellebore. Jalapin. In jalap-resin; soluble in ether. Leptandrin. Leptandra, or Culver's root. Myronic Acid (C 10 H 19 NS 2 10 ). In black mustard as K salt (sinigrin); this salt decomposed by ferment myrosin as follows: KC 10 H 18 NS 2 10 = C 6 H 12 6 + C 3 H 5 NCS (allyl mustard oil) + KHS0 4 . Mustard plasters are rendered inert by hot water, which coagu- lates ferment myrosin and prevents formation of sulphocyanate, to which the mustard owes its virtue. Phloridzin. Root-bark of apple, pear, plum, and cherry; causes glycosuria. 232 THE CARBON COMPOUNDS. Populin. Bark and leaves of trembling-poplar; with ben- zoic acid. Quercitrin. Sumach, and grape-vine; coloring principle. Salicin (C 13 H 18 7 ). Willow- bark and leaves; combination of C 6 H 12 C e and oxybenzyl alcohol, C 6 H 4 OH.CH 2 OH; white, crystalline, soluble in 28 H 2 or 60 alcohol; H 2 S0 4 turns deep red. Santonin. Wormseed; shining, colorless prisms, turned yellow by light; sparingly soluble in H 2 0, but more so in alco- hol and ether. Identification of Santonin. Heat on porcelain and add H 2 S0 4 and an equal volume of very dilute Fe 2 Cl 6 . A red color is developed, turn- ing purple, then violet. Saponin. Quillaia, senega, horse-chestnut, etc.; white, friable powder; frothy foam, like soap. Scammonin. Scammony-resin; soluble in ether. Scillitin. Squill-bulbs. Solanin. Solanum species and potato-sprouts; poisonous. Sinalbin. White mustard. Strophanthin. Seed of African climbing plant used for arrow-poison; heart-tonic; colored dark green by H 2 S0 4 , turn- ing red-brown. Tannin (C 14 H 10 9 ). Wide distribution; acid reaction; soluble, astringent, bitter; incompatible with nearly every- thing; tea, leather, inks, dyeing. Styptic collodion, a saturated solution of tannin, is a valuable styptic, particularly for bleed- ing gums. Experiment. Boil 1 gm. of tannin for fifteen minutes in 10 c.c. of 5-per-cent. H 2 SO 4 ; then neutralize with excess of marble-dust and test filtrate for glucose. VEGETABLE COLOEING MATTERS. Litmus. A lichen; litmic acid, red; salts, blue. Curcumin. Resin of turmeric root; yellow color, turned red-brown by alkalies; soluble in CHC1 3 (saffron and mustard not); used to color mustard, chow-chow, and vermicelli. Chlorophyl. Eesinoid mixture of xantho- and cyano-; con- tains Fe; necessary to life and growth of plants; soluble in alco- hol and ether, but not in water. Hematoxylin. Logwood; yellow solid, red liquid; dye and section-stain. Carminic Acid. Coloring constituent of cochineal (dried female insects on cactuses); carmin prepared by extracting COLORING MATTERS. 233 cochineal with H 2 and pptg. with alum and lime reddish- purple magma soluble in water and alcohol and KH 4 HO. Face- rouge is carmin with starch or French chalk; lac-dye is a cheap form of cochineal. Indican. In woad and indigo plant; acids change to indigo-blue and indiglucin. Indigo-blue (C 16 H 10 N 2 2 ), insol- uble in alcohol, water, or ether; soluble in H 2 S0 4 or CHC1 3 ; reduced to indigo-white (C 16 H 12 N 2 2 ) by nascent H; has been prepared synthetically from toluene. Ruberythric, or Rubianic, Acid. A glucosid in madder- root; yields by fermentation alizarin (turkey-red) and purpurin. Xanthorhamnin. Coloring matter of buckthorn, or Rham- nus tinctoria. Bixin and Orellin. Red and yellow scales, fruit of B. orellana; colors yellow (annatto butter). Brasilin. Brazil wood; amber yellow; fused with KHO yields resorcin. Saffranin (Polychroit). Glucosid in saffron, or crocus; colors food yellow. Santalin. Crystalline resinoid in red saunders wood; also barwood and camwood. Alizarin ( orthodioxyanthraquinone) is obtained from madder-root (Rubia tinctoria); now usually formed by synthesis from anthracene. Fine red crystals, readily soluble in alcohol and ether. Turkey-red dye; violet or purple with alkalies; various colored lakes with metallic oxids: red with Al and Sn, violet-black with Fe, reddish blue with Ca. Naphthazarin, or alizarin black, is dioxynaphthoquinone [C 10 - H 4 (OH) 2 2 ]. Alizarin orange is obtained by the action of N 2 4 on alizarin; alizarin blue by heating alizarin orange with glycerin and H 2 S0 4 . Alizarin brown, or anthragallol, is an isomer of purpurin, or trioxyanthraquinone [C 14 H 5 (OH) 3 0,]. Triphenyl-methane Coal-tar Dye-colors. Malachite-Green Group of Diamido Derivatives. Malachite green (colorless base): fC 6 H 4 N(CH 3 ) 2 C 6 H 4 N(CH 3 ) 2 Commercial dyestuff: chlorhydrate or ZnCl 2 double salt. 234 THE CARBON COMPOUNDS. Rosanilin Group. Fuchsin, or magenta; chlorhydrate of rosanilin: fC 6 H 3 CH 3 NH 2 C^C 6 H 4 NH 2 [ C 6 H 4 NH HC1 Methyl violet, or pyoktanin also. Eosolic-Acid Group. These are acid dyes of no present importance, and are formed from anilin bv substitution of HO for NH 2 . Phthalein Group. Produced by reaction of a molecule of phthalic anhydrid [C 6 H 4 (CO) 2 0] on 2 molecules of phenol, with liberation of H 2 0. Phenol-phthalein is an indicator for alkalies; fluorescein, or resorcin-phthalein, is used as the Na salt (uranin) to dye wool yellow; eosin is the K salt of tetra- brom-fluorescein, and dyes silks and woolens reddish. Noso- phen (tetra-iodo-phenol-phthalein) contains 60 per cent, of iodin. It is yellow and insoluble, but forms soluble salts with alkalies. Eudoxin is a red-brown, insoluble Bi salt of nosophen. UNCLASSIFIED BITTEK PRINCIPLES. Aloins. Yellow, bitter, minute needles from Aloes Barba- densis or Socotrina; slightly soluble in water, but more so in alcohol; barb-, soc-, or nat- aloin. Identification of Aloin. Dissolve in strong H 2 SO 4 and a little HNO 3 , and dilute with H 2 0: A yellow color (blue, nataloin; no color, socaloin), turning deep claret with excess of NH 4 HO. Cantharidin. Spanish-fly blister. Cimicifuga. Black snakeroot. Cotoin. Bolivian coto. Cubebin. Cubeb-berries. Elaterin. Neutral principle deposited by juice of "squirt- ing cucumber"; most powerful hydragog known. Euonymin. Wahoo-bark. Phytolaccin. Crystalline substance from poke- root and fruit. Picrotoxin. Crystalline bitter convulsant from Cocculus Indicus. Serpentaria. Virginia snakeroot. Quassin. Quassia-bark; simple bitter. PHENOLS. 235 PHENOLS. These are substitution products of benzene, in which one or more atoms of H are replaced by OH. They stand between organic acids and true alcohols; they differ from alcohols in not oxidizing to aldehyds and acids, but they form ethers. Phenol (phenic, phenylic, or carbolic acid), C 6 H,.OH, is manufactured from coal-tar oil distilled at 150 to 190. It appears in crystals with characteristic aromatic odor and sweet, burning, and numbing taste. It fuses at 35 to 41; b.p., 178; and is liquefied by 5 parts and soluble in 20 of H 2 and in nearly every other solvent. It is neutral or faintly acid. It coagulates albumin and collodion. Phenol is a valuable sur- gical antiseptic, but very poisonous. The salts of phenic acid are termed phenates or carbolates, as NaC 6 H 5 0. Phenol crys- tals and solutions tend to turn red. Identification of Phenol. Fe 2 Cl 6 gives a permanent violet color. Br water gives white ppt. of tribromphenol. NH 3 , or Labarraque's solu- tion, colors blue. Cresol (cresylic acid), C 6 H 4 .CH 3 .OH, is impure carbolic acid obtained from coal-tar by fractional distillation. Among its derivatives are creolin, lysol, and solveol. Creasote is a mixture of phenols, especially guaiacol, C 6 H 4 .- OH.OCH 3 , and creosol, or wood-tar, C 6 H 3 .CH 3 .OH.OCH 3 , ob- tained from coal-tar. It is a yellow, oily liquid with smoky odor and burning taste, soluble in 150 H 2 and freely in other solvents, except glycerin; b.p., 205 to 215; miscible with an equal volume of collodion. It is used chiefly as an intestinal antiseptic. Identification of Creasote. Fe 2 Cl 6 gives a violet color, changing to green and brown. Resorcin, C 6 H 4 (OH) 2 , appears in colorless crystals which have a sweet taste and are very soluble. It is formed by fusing resins with caustic alkalies. It is only slightly poisonous, and is used as a gastro-intestinal antiseptic and in manufacturing dyes. Fe 2 Cl 6 gives a blue or violet color with weak solutions. Pyrocatechin (catechol) and hydroquinone are, respect- ively, ortho- and para- dihydroxy-benzene. Guaiacol is mono- methyl catechol; its carbonate is prepared by saturating with XaHO and treating with COC1 2 . Pyrogallin [C 6 H 3 (OH) 3 ] appears in glistening, white, gen- erally soluble needles, prepared by heating gallic acid to 200, by which C0 2 is driven off. It is a good reducing agent, and 236 THE CARBON COMPOUNDS. is used as a developer (deoxidizing agent) in photography. It turns red with ferric, blue with ferrous, salts. Experiment. Show rapid oxidation (darkening) of pyrogallin with alcoholic solution of KHO when exposed to the air. For the same reason it furnishes a delicate test for traces of HNO 3 . Phenol-phthalein, C 20 H 14 4 , is prepared by dehydrating phthalic acid by heating and then treating the anhydrid with phenol in presence of H 2 S0 4 , which removes another molecule of H 2 0. It is a valuable indicator in alkalimetry. The naphtols (a. and I.), C 10 H 7 OH, are similar to the phenols, being intestinal antiseptics derived from naphtalen. Betanaphtol is used medicinally, as alphanaphtol is poisonous. It appears in shining plates with carbolic odor and burning taste. It is readily soluble except in H 2 (1000 parts). Aque- ous solutions are colored green by Fe 2 Cl e . Sodium naphtol (microcidin), C 10 H 7 .0]Sra, is used in aqueous solutions as a dis- infectant for cleansing dental instruments. NITEO-DERIVATIVES. Nitrobenzene (mirbane essence), C 6 H 5 N0 2 , is a yellow, oily compound, formed by nitration of benzene. It has the odor of bitter almonds and is used to flavor confectionery and per- fumery. It is the source of anilin and coal-tar dyes. Picric or carbazotic acid (trinitrophenol), C 6 H 2 (N0 2 ) 3 OH, is prepared by acting on phenol, silk, or wool with HN0 3 . It ppts. alkaloids and albumin, and is used as a yellow dye and in explosives (lyddite). (See also "Ethers" and "Carbohydrates.") THIO-COMPOUNDS. Sulphocarbolic acid, HS0 3 .C 6 H 4 OH (phenol-sulphonic, or sozolic, acid), is formed by dissolving phenol in strong H 2 S0 4 . Na and Zn sulphocarbolates are w r hite soluble salts used as intestinal antiseptics. Ichthyol (Na or NH 4 , ichthyo-sulphonate) , C 26 H 36 S : ,Na 2 (5 , is a brown, tarry, strong-smelling liquid, obtained by dry dis- tillation of a bitumen found in Tyrol. Mercaptans (so called from their affinity for HgO), or hydrosulphids, are alcohols in which S has replaced 0. They are liquids, insoluble in H 2 0, inflammable, and with an un- pleasant odor like leeks. They may be formed by treating haloid ethers with KSH. THIO-COMPOUNDS. 237 C 2 H 5 C1 + KSH = KC1 + C 2 H 5 SH (ethyl mercaptan) Combined with oxids they yield mercaptids; with aldehyds, mercaptals; with ketones, mercaptols. The oxidation of mer- captans yields sulphonic acids; of mercaptols, sulphonals. The hypnotic, sulphonal CH 3 \ p / S0 2 C 2 H 5 CH 3 / ^ \ S0 2 C 2 H 5 (diethyl-sulphon-dimethyl-methane) is formed by the reaction between acetone, ethyl mercaptan, and K 2 Mn 2 8 . It is a color- less, tasteless, odorless, crystalline substance, soluble in hot water. Experiment. Heat a mixture of sulphonal and wood charcoal, and note characteristic odor of mercaptans. Trional, another hypnotic, is diethyl-sulphon-methyl-ethyl- methane: CH 3 \p/C 2 H 5 S0 2 C 2 H 5 / V\ C 2 H 5 S0 2 and tetronal is diethyl-sulphon-diethyl-methane: C 2 H 5 \ r /C 2 H 5 S0 2 C 2 H 5 / ^ \ C 2 H 5 S0 2 These are soluble in boiling water, alcohol, and ether. Allyl sulphid ("garlic oil"), (C 3 H 5 ) 2 S, is the most impor- tant thio-ether. It is obtained from garlic-leaves and the seeds of many cruciferse. AMIDO-PHENOLS. These are formed by reduction of the corresponding nitro- phenols. The ethyl ethers of para-amido-phenol, C 6 H 4 .OH.NH 2 , are termed phenetidins. From para-phenetidin, C 6 H 4 .OC 2 H 5 .- NH 2 , phenacetin (acetparaphenetidin), C 6 H 4 .OC 2 H 5 .NHC 2 H ? 0, is formed by treating with glacial acetic acid. It is a crystalline substance, soluble in alcohol, and. is one of the best and safest of the coal-tar remedies. Phenocoll, or glycocoll phenetidin, has the formula C 6 H 4 .OC 2 H v NH.COCH 2 NH a . Methacetin, or para-acetanisidin = C 6 H 4 .OCH 3 .NH.C 2 H 3 0. 238 THE CARBON COMPOUNDS. COMPOUND AMMONIAS. Amins are alkyl substitutes of NH 3 . They are primary, secondary, and tertiary, according as 1, 2, or 3 atoms of H are replaced. They are mon-, di-, or tri- when 1, 2, or 3 molecules of NH 3 are represented. They contain no 0. They are char- acterized by a strong, disagreeable odor, often like dead fish. With HN0 2 primary amins yield corresponding alcohols. Amins also combine with acids to form salts. The three methyl monamins [CH 3 NH 2 , (CH 3 ) 2 NH, and (CH 3 ) 3 N] are found in herring brine and many other decom- posing products. The first is a combustible gas; the others, liquids. Diethylen-diamin [(C 2 HJ 2 (NH) 2 ~\, or piperazin, appears in rhombic plates, readily soluble. It is used as a solvent for uric acid and gouty concretions. Urotropin, hexamethylen-tetramin, is a crystalline substance soluble in water, used as a genito-urinary antiseptic. Saccharin (anhydro-ortho-sulphamin-benzoic acid), C^H^- COS0 2 NH, is a coal-tar product, from toluol, 280 times as sweet as cane-sugar. It is soluble in alcohol and ether, and may be detected by this fact. Found in the cadaver are the diamins putrescin and cadav- erin. Isoamylamin is a very poisonous ptomain sometimes present in decomposing yeast and codliver-oil. Cacodyl, or diarsenic tetramethyl [As 2 (CH 3 ) 4 ] ) is a color- less, very poisonous liquid with an extremely offensive odor. It takes fire on exposure to air. Cacodyl oxid [As 2 (CH 3 ) 4 0] is formed by dry distillation of a mixture of As 2 3 and KC 2 - H 3 2 . It is a poisonous, oily liquid which, when oxidized with HgO, yields cacodylic acid [(CH 3 ) 2 AsO.OH], an odorless, crys- talline substance, non-poisonous, and recently used in medicine. Given hypodermically it sets up symptoms of As poisoning. Amids consist of an acid radical with the group amidogen, NH 2 . They result when NH 2 replaces OH in acids. They con- tain C, N, 0, and H. Imids have the group NH instead of KH 2 . Acetamid, C 2 H S O.NH 2 , is prepared simply by heating NH 4 C 2 H 3 2 , driving off H 2 0. It appears in soluble crystals with a mousy odor. Carbamid, or urea [(NH 2 ) 2 CO^, was about the first or- ganic compound prepared synthetically, by heating its isomer: NH 4 CNO. It is the chief solid constituent of urine. Formamid, NCHO.H 2 , is a colorless liquid which com- bines with chloral to form the soluble crystalline hypnotic chloralamid: COMPOUND AMMONIAS. 239 N.CHO.H 2 .C 2 HC1 3 Phenylamin, or anilin, NH 2 C Q H 5 , is a colorless, oily liquid, nearly insoluble in H 2 0. It is prepared by treating C H 6 with HN0 3 and nascent H (Fe and HC1). It is a narcotic poison, and is the basis of the anilin dyes (not poisonous), which are made by oxidation processes. Bleaching powder and anilin give a purple dye; K 2 Cr 2 7 , H 2 S0 4 , and anilin, blue: NH 2 C 6 H 5 + 2C 7 H 9 N" (toluidin) + 30 = C 20 H 19 N 3 (rosan- ilin) + 3H 2 0. Experiment. Make rosanilin hydrochlorate by warming 2 gm. of HgCl 2 and 3 or 4 drops of anilin until the color becomes green and then purple. Let cool and add a few drops of alcohol and a drop or two of HC1. Then stir into beaker of H 2 0. Anilids are derivatives of anilin obtained by replacing am- monia or amido H by alcohol radicals or acid radicals. Ace- tanilid, or phenyl acetamid, [H NJC 6 H 5 [C 2 H 3 is prepared by boiling anilin with glacial acetic acid. It appears in white, unctuous crystals, sparingly soluble in H 2 0, more freely in alcohol. On warming with HC1 it is decomposed into anilin and acetic acid. Experiment. Prove presence of anilin in acetanilid by heating to- gether a mixture of equal parts of acetanilid and powdered NaHO. After a few minutes invert test-tube and allow oily globules of anilin to run out, keeping up the warming process. Identification of Acetanilid. Boil 0.1 gm. with 1 c.c. of HC1 and then add 1 c.c. each of saturated phenol solution and saturated solution of bleaching powder. A cloudy, red mixture is formed, which turns dark blue on supersaturating with NH 4 HO. Exalgin, or methyl acetanilid, is another pain-reliever, sol- uble in alcohol. Amido-acids are acids in which 1 atom of H has been re- placed by KE 2 . They possess both acid and basic properties. Amido-acetic acid (glycin, glycocoll) has the formula CH 2 .NH 2 .- COOH. Amido-formic, or carbamic, acid, NH 2 .COOH, is pres- ent as a salt in ordinary ammonium carbonate. It is formed by direct union of C0 2 and NH 3 , C.NH 4 .NH 2 2 . Leucin is amido-caproic acid: C 3 H 10 .NH 2 .COOH. Like its congener, tyrosin, it is a product of albuminous decomposition in the in- testines. 240 THE CARBON COMPOUNDS. PYRIDINS. These tertiary monamins are colorless liquids, insoluble in water, but soluble in alcohol, ether, and fixed oils. Pyridin, C 5 H 5 N, is present in bone-oil, coal-tar naphtha, and tobacco- smoke. It has a sharp, characteristic odor. Pyrrol, C 4 H 5 N, is also in coal-tar and bone-oil. lodol, C 4 I 4 NH, is a light-brown, .odorless, tasteless powder containing 89 per cent. I. It is de- rived from pyrrol by treating with I in presence of oxidizing agents. It is used as a substitute for CHI 3 , and is not toxic. Quinolm, or chinolin, C 9 H 7 N, is prepared by distilling quinin or cinchonin with potash. It corresponds with naph- talin in which one CH group is replaced by N". Kairin, C 10 H 13 .NO.HC1, is the hydrochlorid of methyl-oxy- chinolin-hydrid. It appears in white crystals soluble in 6 H 2 or 20 alcohol. Thallin, C 10 H 1:L NO, or tetra-hydro-paramethyl-oxyquinolin, is a white, aromatic, crystalline substance, generally soluble. It is colored a bright green by Fe 2 Cl 6 and other oxidizing agents. AZO AND DIAZO COMPOUNDS. The group N" = N links an alkyl to an acid radical in diazo; two alkyl radicals in azo compounds. These com- pounds are colorless, crystalline substances, soluble in water, and are formed by treating aromatic amins with HN0 2 . From azo-benzne, C 6 H 5 N = N C 6 H 5 , the beautiful azo dyes are derived. HYDEAZINS. These are derivatives of hydrazin, or diamin, NH 2 NH 2 , a colorless, stable, alkaline gas, and are formed by replacing H with alkyl radicals. Phenyi-hydrazin, C 6 H 5 NH NH 2 , prepared by reduc- tion of diazo-benzene, is a colorless, oily liquid, soluble in alco- hol and ether, and a powerful reducing agent, forming char- acteristic crystalline compounds called osazones with various sugars, and hydrazones with aldehyds. Antipyrm, or phenazone (phenyl-dimethyl-pyrazolon), C 1 - H 12 N 2 0, is derived from phenyl-hydrazin by heating with di- acetic ether [(C 2 H 3 2 ) 2 C 2 H 5 0], forming phenyl-methyl-pyraz- olon, which is then made to take up another methyl group in place of H. Antipyrin appears in white crystals, very soluble in H 2 and other solvents. ALKALOIDS. 241 Identification of Antipyrin. Fe 2 Cl c gives deep red; HNO 3 yellow, then intense red on warming; KNO 2 and HC 2 H 3 O a (a few drops of each) give an intense-green color. NITRILS AND CARBYLAMINS. These are isomeric compounds of organic radicals with CN. Nitrils, or cyanids. have the general formula R CEEEN; carbylamins, or isocyanids, B NE=C. The nitrils are vola- tile liquids or solids, yielding organic acids when heated with H 2 in presence of mineral acids or alkalies: e.g., CH 3 CN + 2H 2 = CHg.COOH + NH 3 . Hence they correspond with acid oxids or anhydrids. They may be formed by heating alkyl iodids with KCN. Fulminic acid, C 2 N 2 H 2 2 , is very unstable. Mercuric ful- minate is made by adding alcohol to a solution of Hg in HN0 3 , and is used as an explosive in percussion-caps, developing a pressure of 43,000 atmospheres by detonating in its own vol- ume. The carbylamins are marked by a disgusting odor and are formed by heating hydrocarbon iodids with AgCN. When heated with H 2 and mineral acids they form amins and or- ganic acids: e.g., CH 3 NC + 2H 2 = CH 3 NH 2 + HCOOH The isosulphocyanates, or mustard-oils, RNCS, break down into an amin, H 2 S, and C0 2 on treating with H 2 and alkalies. The most important member of this group is allyl sulpho- cyanate, C 3 H 5 NCS, found in mustard-seed. ALKALOIDS. Alkaloids are physiologically active vegetable (or animal) nitrogenous principles, or natural organic bases, derived from pyridin (C 5 H 5 N), chinolin (C 9 H 7 N), and isochinolin. The liquid and volatile alkaloids are amins; the solid non-volatile, amids (these contain 0). The latter is much the larger class. Their names all end in in (or ine), English; ina, Latin. The vegetable alkaloids exist in combination with tannic, malic, *. meconie, H 3 C 7 H0 7 (opium), kinic (cinchona), and other acids. They are extracted from the comminuted plants by dissolving^ out in H 2 or alcohol, or by treating with dilute acids, then with CaO or MgO, and then dissolving in alcohol, ether, chlo- roform, or dilute acids. They are generally white, bitter, and insoluble in H 2 0, but soluble in other solvents. Their salts are 242 THE CARBON COMPOUNDS. formed by direct addition of the acid; they are more soluble in water and in alcohol; hence are employed in medicine rather than the simple alkaloid. Alkaloids and alkaloidal salts are in- compatible with their reagents and with bases, carbonates, and bicarbonates. Many of them are poisonous. The chemic anti- dote for all is tannin or well-diluted K 2 Mn 2 8 (grain for grain of poison). Test Precipitants. 1. Taimic acid: Resulting tannates are diffi- cultly soluble in cold water, but soluble in alcohol or excess of tannic or other acids. 2. Haloid salts of Hg: Double nearly insoluble salts. Mayer's solution [HgI 2 (KI) 2 ] consists of 13 V gm. of HgCl 2 and 50 gm. KI in 1000 c.c. of H 2 0. It ppts. all the alkaloids. 3. Picric acid: Cinchona bases especially. 4. Phosphomolybdic and phosphotungstic acids: Ppt. great ma- jority of alkaloids. 5. Potassium chromate and dichromate: Ppt. concentrated aqueous solutions as chromates. 6. Chlorids of Au and Pt: Crystalline double salts, with many alkaloids. Color-reactions. Dehydration : H 2 S0 4 , ZnCl 2 , P 2 O 5 . Oxidation: HNO 3 , Cl, Br, NaCIO; H 2 S0 4 and KC1O 3 or K 2 Mn 2 O 8 ; chromic, molybdic, iodic, and tungstic acids. Special reactions: Fe 2 Cl 6 , HC1, H 2 S0 4 , sugar. VOLATILE ALKALOIDS. These are colorless, oily liquids, and turn brown on ex- posure to the air. Coniin is marked by a repulsive odor, and is obtained from hemlock-fruit. It acts as a motor paralyzant poison. Nicotin, C 10 H 14 N 2 , is the poisonous principle of to- bacco, in which it is present to the extent of 1 to 7 per cent. of dry leaf, in combination with malic and citric acids. It has a peculiar strong odor. When tobacco is smoked the nicotin is converted largely into pyridin. Nicotin is a narcotic poison, and 1 m. has proved fatal. Identification of Nicotin. Violet with HC1; orange with HN0 3 . Lobelin, from lobelia, or Indian tobacco, has an odor like tobacco mixed with honey. Spartein, from the leaves and branches of broom, is an odorless, very bitter cardiac tonic. Spigelin, from spigelia, or pinkroot, is used as a vermifuge for round-worms. NON-VOLATILE ALKALOIDS. Solanaceae. These are closely allied mydriatics and deliri- ants, having the formula C 17 H 23 N"0 3 . They quicken the pulse and respiration, and may cause death by overstimulation, lead- ALKALOIDS. 243 ing to paralysis. The most potent and important is atropin, from Atropa belladonna. Its sulphate is commonly employed. Henbane has two important alkaloids, hyoscin and hyoscyamin, duboisin being another name for both; the hydrobromate is the common salt. Daturin is obtained from stramonium; sola- nin from bitter-sweet and potato-sprouts; and scopolamin (identic with hyoscin) from scopolia. Baryta-water decom- poses atropin into tropin, C 8 H 15 N0 3 , and this furnishes homat- ropin. Identification of Atropin. Boiling with dilute H a S0 4 gives an orange-flower odor, which is changed to bitter-almond odor and green color on adding K 2 Cr 2 O 7 . Cinchona Group. Peruvian bark contains at least 5 per cent, of alkaloids, of which one-half should be quinin. Of the thirty-two cinchona alkaloids, the chief four are quinin (C 20 - H 24 N 2 2 ), quinidin, cinchonin, and cinchonidin. These are all effective febrifuges and antiperiodics. The principal salts of quinin are the sulphate, bisulphate, hydrobromate, hydrochlo- rate, and valerianate. The neutral sulphate is soluble in 740 H 2 or 65 alcohol. The hydrochlorate is most soluble: in 34 of water. The cumulative effects of quinin are due to rapid absorption (fifteen minutes) and slow elimination (two or three days). Identification of Quinin. Solutions in excess of dilute H 2 SO 4 show a strong fluorescence. To 10 c.c. solution of quinin add 2 m. of Br water and excess of NH 4 HO, and get emerald green of thalleioquin. Herapathit Test. Dissolve Y 2 gm. of alkaloid in 15 c.c. of alcohol of 0.83 sp. gr., diluted with 5 c.c. of water, and acidulate fluid with 2 c.c. of 10-per-cent. H 2 SO 4 ; add to this solution of 0.2 gm. of I in 10 c.c. of alcohol (0.83 sp. gr.) ; warm mixture slightly and allow to cool. Note the quite insoluble microcrystalline ppt.: dark green quinin ; red = quinidin; yellow cinchonidin; no ppt. = cinchonin. Opium, or Thebaicum, Group. Of the seventeen alkaloids extracted from poppy, morphin, C 17 H 19 N0 3 (10 to 14 per cent.), is chief. Narcotin, an hypnotic, constitutes 4 per cent.; papav- erin, a narcotic, 1 / 2 to 1 per cent.; codein, an analgesic, 0.2 to 0.8 per cent.; and thebain, a tetanic convulsant, 0.2 to 0.5 per cent. Opium may be deodorized with ether, which dissolves out narcotin. The sulphate is the common salt of morphin. It dissolves in 24 H 2 0, 702 alcohol. The hydrochlorate of morphin on heating with HC1 is dehydrated into the emetic, apomorphin hydrochlorate. Solutions of this on exposure to air turn green. Other artificial derivatives are heroin (diacetyl- 244 THE CARBON COMPOUNDS. rnorphin), dionin (hydrochloric! of monoethyl-ester of morphin), and peronin (hydrochlorid of benzyl ether of morphin). Identification of Morphin. HN0 3 gives a red color, fading to yellow and discharged by reducing agents. Fe 2 Cl 6 colors blue, turning green. Identification of Codein. This shows a claret-red color with Br water on shaking and adding NH 4 HO. Strychnos Alkaloids. Strychnin and brucin are found in the seeds of S. nux vomica and 8. ignatia and in S. tiente^ the deadly upas-tree root-bark of Java, used as an arrow-poison. Strychnin is so bitter as to be perceptible in a dilution of 1 to 700,000. Its usual salt is the sulphate, It produces death by asphyxia from tetany of the respiratory muscles. (Smallest fatal dose, V 4 grain; time, 5 minutes to 6 hours.) Brucin is similar, but milder in action. Identification of Strychnin. H 2 S0 4 and a crystal of K 2 Cr 2 7 give blue, running through a rainbow of colors to red-yellow. Identification of Brucin. It turns blood-red with HNO 3 , yellow on heating, violet on adding Na 2 S 2 O 3 . Physostigmin, or Eserin. This myotic is extracted from Calabar bean. The chief salts are the salicylate and sulphate. It produces death in the same way as strychnin. Cocain. The hydrochlorate is readily and generally sol- uble. It is a local anesthetic. Less than a grain has produced death by respiratory paralysis or tetanic spasm of the heart. Eucain is a valuable and less toxic derivative; #-eucain is less irritant than a-eucain. Pilocarpin. This is a valuable sudorific extracted from jaborandi-leaves. The nitrate and hydrochlorate are the salts in use. Jaborin, from the same source, is less important. Aconitin. This alkaloid is present in monk's-hood or wolf's-bane. One-twelfth grain has caused death by paralysis of heart and respiration. Veratrin. Veratrum (poke-root, hellebore) contains jervin, cevadin, pseudojervin, protoveratrin, etc. Identification of Veratrin. H 2 S0 4 gives a yellow color, turning scarlet and violet-red. Hydrastis Group. Berberin is a yellow alkaloid found in barberry, golden-seal, etc. Hydrastin is the white alkaloid of hydrastis; it oxidizes to yellow needles of hydrastinin. These three alkaloids are astringent and antiseptic. Piperin appears in pale-yellow crystals, and is present in both black and white peppers. The ipecac alkaloids are emetin ALKALOIDS. 245 and cephalin. Theobromin is present in cacao-seeds (1 or 2 per cent.) and kola-nuts. Caffein, thein, or guaranin (methyl- theobromin) is the active principle of tea (2 to 4.5 per cent.), coffee (1.2 per cent.), mate (0.2 to 2 per cent.), guarana (5 per cent.), and kola-nut. Aspidospermin is found in quebracho. Gelsemium contains the alkaloids gelsemin and gelseminin. The Anhalonium Lewinii, a member of the cactus family, con- tains an hypnotic alkaloid, pellotin, and an intoxicating alkaloid called mezcalin. ANIMAL ALKALOIDS. Ptomains are products of putrefaction of albuminous sub- stances in dead or living bodies. Like vegetable alkaloids, they are solid or liquid, fixed or volatile, amorphous or crystalline, bitter or tasteless. Their odor may be wanting, or sweet and aromatic, or cadaveric. In chemic reactions they correspond closely to vegetable alkaloids, for which they may be mistaken. They differ from most vegetable alkaloids in being optically inactive. The methylamins and ethylamins are not poisonous. The following are all toxic: Putrescin and cadaverin, in corpses; tyrotoxicon, C 6 H 5 IS[ 2 , in putrid cheese, milk, and cream (ice- cream, cream-puffs); muscarin, in decomposed flesh and fungi; mytilotoxin, C 6 H 15 N0 2 , in oysters and other mussels; neurin, in decomposing meat; and cholin, in animal tissues, hops, and ergot. Leucomains are formed in the living body by retrograde metamorphosis with insufficient 0. They are much increased in anemia, chlorosis, and constipation. They are mostly non- toxic. Toxins are poisonous bases or albumins, the products of specific bacteria and the direct cause of most infectious dis- eases. Diphtheria poison is a white, amorphous toxalbumin. The typhoid bacillus produces typhotoxin, C 2 H 17 N"0 2 . The tetanus bacillus produces two toxins, tetanin and spasmotoxin, both of which excite tonic and clonic convulsions. Soluble antitoxins of unknown composition are set free from the white blood-cells and the fixed tissues. They antag- onize the toxins and account for artificial immunity. A normal serum neutralizes ten times as much toxin. An antitoxic unit neutralizes enough toxin (when injected at the same time) to kill one hundred guinea-pigs. Very concentrated antitoxic serums are now in use (3000 units per c.c.). 246 THE CARBON COMPOUNDS. PROTEINS. Kepresentatives of this group are essential parts of proto- plasm and of animal and vegetable fluids. They are very com- plex substances with hundreds or thousands of atoms in a mole- cule, chiefly C (50 to 55 per cent.), H (7 per cent.), (20 to 24 per cent.), N (15 to 18 per cent.), and S (in most, 1 / 3 to 2 1 / 2 per cent.); P and Fe in a few. The average composition is rep- resented by the formula C 144 H 224 N 36 44 S 2 . They yield NH 3 , H 2 S, fatty acids, amido-acids, etc., on decomposition. Experiment. Prove presence of S in white of egg by boiling with Pb(HO) 2 [made by adding NaHO to Pb(C 2 H 3 2 ) 2 solution till ppt. first formed has dissolved]. Proteins are elaborated by plants from NH 3 , nitrates, ni- trites, etc. They are stored up as minute granules (sometimes crystalline) in seeds, roots, and tubers. Animals derive all their proteins from vegetable sources, and eventually break them down into simpler compounds. Proteins are colorless, odorless, nearly tasteless substances, amorphous and non-dialyzable (except peptons) and levorota- tory. They easily putrefy, and are readily coagulated by heat, mineral acids, alcohol, and mineral salts. They are converted by digestive juices into acid or alkali albumins, then albumoses, and finally peptons. On heating dry they char and give forth the odor of burnt horn or wool. The classes of proteins and the chief members of each class are shown in the following table. It is a noteworthy fact that the same protein may exhibit different properties under varying conditions and in different parts of the body. Native Albumins. Sol- uble in distilled water ; coagulated by heat. Serum-albumin 4 to 5 % in human blood ; used in dyeing, calico-printing, and refining cane- sugar. Cell -albumin. Muscle-albumin (myoalbumin). Milk-albumin (lactalbumin) 0.75% in cows' milk ; 1.25 in woman's milk. Egg-albumin white of egg ; pptd. by ether (serum-a., not) or by HC1 (ppt. not soluble in excess as with serum-a. ) ; used as a glaze and a vehicle for colors in calico-printing, for soften- ing leather, and in book-binding and photog- raphy. Plant-albumin flocculi on heating plant-juices ; leucosin in wheat, rye, barley. Paralbumin ( pseudomucin ) found in fluid of ovarian cysts. PROTEINS. 247 Globulins. Insolubl e in pure H 2 O ; soluble in dilute solutions of neutral salts (pptd. by excess) ; coagu- lated by heat ; pptd. by current of CO 2 , by diluting freely with H 2 O, or by removing salt by dialysis. Serum -globulin (paraglobulin, fibrinoplastin ) 2.2 % of blood-plasma. Fibrinogen pptd. by saturating with NaCl ; changed to fibrin by f. -ferment. Myosinogen (muscle-plasma) yellowish fluid clot after death (rigor mortis) : extracted with 10$ NHci\ci Ul . ,,.., v .. viio.i >;au uo iiCJlwu. ^, A copper steam-bath with tubes supplying water and allowing the excess to escane thus maintaining a constant level. The funnel above excludes dust 3 A sulphuric l3!ff^ 1 ^L*?"r tedwl * air - r " Unp - Iu front are evaporating dishes of porcelain, platinum, and glass. 17 258 ANALYSIS. Fig. 37. Apparatus for Filtration. (Kockwood.) 1, A funnel fitted to a filtering flask which is connected with a pump for the pro- duction of a vacuum, and consequently an increase in the rapidity of the filtration. 2, A support holding funnels for filtration. 3, Washing bottles. In front are packages of filter-paper with two plaited filters. 2 3 Fig. 38. Apparatus for Fusion. (Rockwood.) 1, Porcelain crucible. 2, Hessian or clay crucibles, with a pipe-stem triangle lean- ing against middle one. 3. A graphite crucible. 4, A platinum crucible with cover. In front are forceps and crucible tongs. FINDING THE METAL. 259 Eeduction on charcoal is usually best accomplished by heating with the blow-pipe the finely-powdered substance, placed in a hollow in the charcoal after mixing with twice its weight of dry KCN and Na 2 C0 3 . Incrustations around the heated spot are due to oxids. Sublime and volatile substances, such as As, are easily recognized by heating in a bent dry glass tube open at both ends, and noting the mirror, or deposit of drops or crystals recondensed in the cooler part of the tube. To separate the metals from each other, we employ a small number of group reagents, each of which throws down a certain group of metals more quickly when heated. HC1 is the gen- eral reagent of the first analytic group (Ag, Pb, Hg 1 ), throw- ing down an insoluble chlorid of each or all of these metals. H 2 S (preferably the gas, added to solution previously acidu- lated with HC1) ppts. as sulphids the metals of the extensive second group, which is further subdivided according as the ppt. is soluble or insoluble in NH 4 HS (made by saturating NH 4 HO with H 2 S). This latter solution (after supersaturating with NH 4 HO) ppts. the members of the third group. (NH 4 ) 2 - C0 3 (1 part of commercial salt dissolved in a mixture of 4 parts of H 2 and 1 part of NH 4 HO) ppts. the alkaline earths, which constitute the fourth group. An aqueous 10-per-cent. solution of Na 2 HP0 4 is the reagent for Mg, or the fifth "group." The metals of the alkalies are left in the final filtrate. These re- agents must be used only in the order mentioned, and must generally be added in excess in order to ppt. the total quantity of metal or metals in each group, which is separated by filtra- tion before passing to the next group. FINDING THE METAL. GROUP I (Pb, Ag, Hgi). ( Group reagent = HC1 . ) {PbCl 2 soluble in boiling water. AgCl insoluble in H 2 O ; soluble in dilute NH 4 HO (1 to 10). Hg 2 Cl 2 insoluble in H 2 O and turned black by NH 4 HO. Separation. 1. Pb dissolved out with boiling H 2 O and repptd. from filtrate with dilute H 2 S0 4 . 2. Ag dissolved from first residue with dilute NH 4 HO and repptd. with HNO 3 . 3. Hg, if present, left as a black residue from filtration of Ag. 2GO ANALYSIS. Blackish ppt. GROUP II (Hg, Bi, Cu, Pb, Cd, Sb, As, Sn-iv, Pt, Au). (Group reagents = HC1 [a few drops] and H 2 S [excess].) Division I (ppt. insoluble in yellow NH 4 HS). Yellow ppt. = CdS. ( HgS brownish f Yellow = Hg. yellow, then I Blue = Cu ( decolorized by black. O (original) | KCN). Bi 2 S 3 . + KHO -{ Bi insoluble in CuS. excess of KHO PbS. Wn't (yellow oxid I J on boiling). Pb soluble in excess of KHO. Division II (ppt. soluble in yellow NH 4 HS on digesting in an evaporating dish). Orange ppt. = Sb 2 S 3 . Brown or blackish ppt. Yellow ppt. First Division SnS. O -j- HgCl 2 on boiling gives a gray ppt. PtS 2 . O + KC1 4 C 2 H 5 HO gives a yellow ppt. Au 2 S 3 . O -j- SnCl 2 gives a purple ppt. As 2 S 3 heated with KCN and Na 2 CO 3 in a bent glass tube gives a black metallic mirror above. SnS 2 O -f KHO gives a white ppt., soluble in excess, not t repptd. on boiling. Separation. 1. Boiling HNO 3 dissolves all ppts. except HgS (black residue). 2. Dilute H 2 SO 4 throws down Pb ( white ) from above solution. 3. Strong NH 4 HO throws down Bi (white) from nitrate of No. 2. Filtrate of No. 3 blue if Cu is present. Yellow = Cd. 4. H 2 S ppts. -j Black = Cu (decolorized and kept in solution \ by KCN while Cd is pptd. with H 2 S). r i. Second Division Boiling ppts. HC1 i 2. Filtrate may contain As yellow if alone, blackish if Au or Pt present ; soluble in (NH 4 ) 2 CO 3 , repptd. by HC1. f Au pptd. by Fe- Residue from As, j SO 4 . soluble in aqua \ Pt pptd. from fil- regia tratebyKCl + I. C 2 H 5 HO. Separated by electrolysis between a piece of Pt (Sb forms a black coat- ing) and a strip of Zn. j Sn, if present, is deposited as a loose, [ metallic sediment. Au Pt GKOUP III (Fe, Co, Ni, Cr, Al, Ce, Mn, Zn, Ca 3 [PO 4 ] 2 ). (Group reagents = NH 4 C1, NH 4 HO [till alkaline], and NH 4 HS.) Division I (ppt. formed by NH 4 HO turned black by NH 4 HS). Black color bleached by HC1 = Fe 2 ( HO ) 6 . O + K 6 Fe 2 Cy 12 (ferrous) or K 4 Fe- Cy 6 (ferric) gives a blue ppt. FINDING THE METAL. 261 f CoS. O 4- KHO gives bluish ppt., turning pink on Black residue from HC1 \ ^.^ } ^ lm ur ISib. O-T-KHO gives green ppt., unaltered on boiling. Dii-ision II (ppt. formed by NH 4 HO unchanged in color by NH 4 HS). Green ppt. = Cr 2 (HO) 6 C A1 2 (HO) B . O-f KHO gives a white, gelatinous ppt., soluble in excess, repptd. by boiling with excess of NH 4 C1. White ppt. \ f Ce leaves a red residue Ce(HO) f O + KHO gives a white on evaporating and /-. (po \ " PPt- insoluble in ex- -I heating. 3 4 I cess. Ca 3 (PO 4 ) 2 is soluble [ in HC 2 H 3 O 2 . Division III (ppt. with NH 4 HO instantly soluble, but NH 4 HS gives a light-colored ppt. ). Flesh-colored ppk = MnS fused on Pt foil with Na 2 CO 3 and KNO 3 forms a green mass of K 2 MnO 4 . White, gelatinous ppt. = ZnS moistened with a drop of Co(NO 3 ) 2 and heated on charcoal it turns green. Separation. 1. HC1 dissolves all the group ppts. except Co and Ni, which are separated by dissolving in aqua regia, then adding KHO in excess ; Ni is pptd., and Co is obtained from filtrate by evaporation. 2. Evaporate HC1 solution nearly to dryness, take up with water, boil with excess of KHO, and filter, saving precipitate. 3. NH 4 C1 ppts. Al (white) on boiling with filtrate of No. 2 and standing. 4. NH 4 HS ppts. Zn (white) from filtrate of No. 3 on standing. 5. Fuse ppt. from No. 2 on Pt with Na 2 CO 3 and KNO 3 ; a green mass indi- cates Mn. Treat mass with boiling water, filter, and save residue for Fe ; ppt. Mn (white) with K 4 FeCy 6 and filter again. 6. Acidulate second filtrate from No. 5 with HC 2 H 3 O 2 and ppt. Cr (yellow) withPb(C 2 H 3 O 2 ) 2 . 7. Dissolve residue from No. 5 in dilute HC1, and ppt. Fe (blue) with K 4 FeCy 6 . 8. When phosphates are present, boil filtrate from Group II till all H 2 S is expelled ; add a few drops of HNO 3 ; heat to boiling again ; add NH 4 C1, NH 4 HO, and NH 4 HS ; and filter, reserving this filtrate, containing phosphates, for the fourth arid fifth groups. GBOUP IV (Ba, Ca, Sr). (Group reagents = NH 4 C1, NH 4 HO, NH 4 HS, and [NH 4 ] 2 CO 3 .) f BaCO 3 . O -f K 2 CrO 4 gives a yellow ppt. White ppt. ^ CaCO 3 . O -f ( NH 4 ) 2 C 2 O 4 gives a white ppt. [ SrCO 3 crimson flame. Separation. 1. Dissolve group ppt. in HC 2 H 3 O 2 . 2. K 2 CrO 4 ppts. Ba (yellow); yellow color of filtrate removed by repptg., washing with water, and again dissolving. 3. Dilute K 2 SO 4 ppts. Sr (white) on standing, from filtrate of No. 2. 4. (NH 4 ) 2 C 2 O 4 ppts. Ca (white) after rendering filtrate of No. 3 alkaline with NH 4 HO. 262 ANALYSIS. GROUP V (Mg). ( Reagents = NH 4 C1, NH 4 HO, NH 4 HS, [NH 4 ] 2 CO 3 , andNa 2 HPO 4 .) White ppt. = NH 4 MgPO 4 feathery crystals under microscope. GKOUP VI. Flame Tests: Na, yellow (shut off by cobalt-blue glass) ; K (and NH 4 ), violet; Li, carmine red. Odor Test: Boiling O with KHO gives odor of NH 3 and vapors, turning moist red litmus-paper blue. [ Na 2 HPO 4 and NaHO ppt. Li (white). Precipitation \ Sodium cobaltic nitrite [Co 2 (NO 2 ) 6 .6NaNO 2 ] ppts. K (yellow) in presence of acetic acid. 1. Na 2 HPO 4 and NaHO, boiling till all NH 8 is expelled, ppts. Li 2 HPO 4 . 2. Sodium cobaltic nitrite ppts. K from nitrate of No. 1, after acidulating with HC 2 H 3 O 2 . Separation J 3 ' Test ori g ina i solution for NH 3 by boiling with KHO. The amount of gas can be estimated volumetrically by passing into a standardized HC1 solution. 4. Na is tested in O by flame test, and is estimated gravimet- rically by subtraction of all other ingredients from the total solids. NOTES. HC1 may ppt. oxychlorids (soluble in excess) of Sb or Bi from solutions of certain compounds of these metals. It also ppts. silica from soluble silicates, and oxids or hydroxids [Zn(HO) 2 , for instance] pre- viously dissolved in alkaline hydroxids. S is sometimes pptd. on addition of H 2 S, with or without a change in color (red-brown ferric compounds become green ferrous), owing to the deoxidizing action of H 2 S, the H becoming oxidized to water, while S is set free. Dilute H 2 SO 4 ppts. all the members of the second division of the second group from solution in NH 4 HS. Acids added to yellow ammonium sulphid (polysulphid) form a soluble NH 4 salt and ppt. S (white and milky), which should not be mistaken for the members of the arsenic division. The third group reagents ppt. also phosphates, borates, oxalates, and silicates of Mg and alkaline earths from their solutions in weak acids. When the first group reagent fails to yield a ppt. add H 2 S to the same tube. When reagents of third group show no ppt., add to same fluid (NH 4 ) 2 C0 3 for fourth group, and Na 2 HP0 4 for fifth group. FINDING THE ACID. 263 FINDING THE ACID, OR RADICAL. RESIDUES PROBABILITIES. (If a liquid, notice reaction to litmus and evaporate to dryness, then heat to redness.) No Residue: Neutral: water (no odor). Strongly acid: some volatile acid (acetic, hydrochloric, nitric, etc.). Residue: Strongly acid: Fusible by heat: non-volatile mineral acids (phosphoric). Residue chars on heating: free organic acid (tartaric, citric, etc.). Neutral or slightly acid: Residue volatile with fumes, but without blackening: salt of vola- tile metal (NH 4 , Hg, Sb, As). Residue blackens and volatilizes in fumes: organic salt of some volatile metal. Residue changes color on heating: Yellow hot, cooling white = Zn. Deep-yellow hot, cooling yellow = Pb. Yellowish brown hot, cooling pale yellow = Sniv. Orange-yellow hot, cooling lemon-yellow = Bi. Red hot, cooling reddish brown = Fe or Ce. Permanent brownish black = Mn. Residue white, darkens on heating, burns and leaves black or gray- ish mass: organic salts of fixed metals. Alkaline residue = K, Na, Li. Non-alkaline residue, effervescing with HC 2 H 3 O 2 Ba, Sr, Ca. Residue that takes fire and continues to burn after removal from flame w r ith dense, white fumes hypophosphite. Strongly alkaline: leaving fixed white alkaline residue. Acidulate some of original with HC1: Effervescence: Without smell = carbonates or bicarbonates of K, Na, or Li. O + HgCl 2 gives a red (carbonate) or white (bicarbonate) ppt. With smell: Of H 2 S = sulphid of alkali or alkaline earth. Of HCN = alkaline cyanid. No Effervescence. Add AgNO 3 to original: Brownish black = hydroxid of alkali or alkaline earth. Yellow phosphate "] White = borate [ of K or Na. J{ rick-red = arsenate J PRELIMINARY EXAMINATION OF SOLID ACIDS AND SALTS. Step I. Heat a portion of the powdered substance on Pt foil: Charring: organic acids or salts (except oxalates), sugar (reduces cupric solution), or alkaloids (odor like burning hair). Ignition: C, S, P, and all organic compounds. Decrepitation: NaCl and other salts containing H 2 O. Deflagration-: chlorates, nitrates, iodates, etc., on charcoal. Irritating vapors: benzoic acid. 264 ANALYSIS. Fusible: most salts of alkalies and some of alkaline earths. Infusible: salts of earths and most silicates and salts of alkaline earths and heavy metals. Step II. Put a portion in tube, cover with water, and render barely acid with dilute H 2 SO 4 : Red vapors: nitrites. Effervescence: Without odor: carbonate evolved gas renders lime-water milky. Effervescence also takes place cold. With odor: Sulphid: like sewer-gas. Sulphite: like burning sulphur (S0 2 ). Cyanid: odor of HCN. Hypochlorite: chlorin odor, greenish-yellow fumes. Step III. Add another drop of H 2 S0 4 , and warm again. These effects often occur in the second step: Characteristic odors: Vinegar = acetate: odor of acetic ether on adding alcohol. Sulphur dioxid = hyposulphite: with deposit of S. Carbolic acid = carbolate : a few drops of Fe 2 Cl 6 erives a violet color. Valerian = valerianate : Cu(C 2 H 3 O 2 ) 2 added to distillate forms a slow, oily ppt., gradually solidifying into greenish-blue crystals. Benzoic acid = benzoate: light-red ppt. with Fe 2 Cl 6 in presence of enough NH 4 OH to render slightly alkaline. HCN: With deposit of S sulphocyanid : blood-red color with Fe 2 Cl 6 . Crystalline deposit, often bluish: Ferrocyanid: ferric salts give a blue ppt. Ferricyanid: ferrous salts give a blue ppt. Step IV. Put a little (original solid) in a dry tube, cover with strong H 2 S0 4 drop by drop, and warm gently, keeping the acid below b.p.: White fumes: Chlorid: odor of HC1; AgN0 3 gives curdy white ppt., soluble in NH 4 OH. Nitrate: faintly-reddish vapors, turning more red on addition of FeS0 4 . Fluorid: fumes etch glass. Benzoate: very irritating vapors (see test above). Succinate: Fe 2 Cl 6 gives a brownish-red ppt. Sulphocarbolate : same tests as for carbolates; also after fusion with KN0 3 and redissolving in dilute HC1 it gives sulphate reaction with BaCl 2 . Ammonium compounds: dense, white fumes on holding near mouth of tube a glass rod dipped in HC1. Colored fumes: Violet vapors of I: lodid: blue with starch paste and Cl water. lodates: blue color with starch paste on adding KI and tartaric acid. Brown vapors of Br: Bromid: orange color when mixed with starch paste and a few drops of Cl water. Bromate: deflagrates on charcoal, leaving corresponding bromid. FINDING THE ACID. 265 Greenish-yellow gas = chlorates: explodes readily; spontaneous ignition of tissue-paper dipped in benzin when dropped into beaker containing chlorate and H 2 SO 4 . Simple cliaiif/e in color: Chromates: orange, then green. Dichromates : turn green at once. Oxids of heavy metals: darken by reduction to metallic state. Effervescence on wiinnuuj, with no odor or change in color: Formate: gives oft CO only, burns with bluish-lavender flame. Oxalate: gives off both CO and CO 2 , thus rendering lime-water milky. Effervescence on warming, with darkening in color: Tartrate: rapid charring and smell of burnt sugar. Lactate: not so dark; odor of sour milk; odor of aldehyd on boil- ing with KJMn.Os. Citrate: slow darkening, with slight odor of burnt sugar. Oleate: charring, with sharp, disagreeable odor of acrolein. Darkening in color without .any very marked effervescence: Tannate: solution forms black ink with FeS0 4 ; no ppt. with gelatin (unless gum is present). Gallate: solution forms a black ink with FeS0 4 ; immediate brown- ish ppt. with gelatin. Pyrogallate: solution turns blue with ferrous, red with ferric salts. Salicylate: very slow darkening; deep-violet coloration with Fe 2 Cl 6 . Meconate: red color with Fe 2 Cl 6 , not discharged by HgCl 2 or dilute HC1. No fumes: Silicate: gelatinous or flaky deposit. Borate: scaly crystals with pearly luster, best seen on cooling. No change whatever: Sulphate: hepar test: heat with a little Na.COg on charcoal in inner blow-pipe flame (reduction to sulphid) ; residue placed on a clean silver coin moistened with H 2 leaves a black stain. Phosphate: solution of (NH 4 ) 2 Mo0 4 in HNO 3 yields a yellow ppt. insoluble in HNO 3 , soluble in NH 4 OH. Phosphite: heated with AgN0 3 yields ppt. of metal Ag; same re- action as phosphate, after heating with HNO 3 . Arsenate: boil with NaHO, filter, exactly neutralize filtrate with dilute HNO.,, add AgN0 3 , and get brick-red ppt. , Arsenite: AgNO 3 gives canary-yellow ppt. of AgoAsO 3 , soluble in excess of NH 4 OH or HNO S . Alkaline oxids: soluble in HC1 or HNO 3 without effervescence: negative findings as to acid radicals except that of solvent. DETECTION OF ACIDS AND ACIDULOUS RADICALS IN SOLUTION. 1 AgN0 3 , Reagent: Neutral or acid (HNOJ reaction: White ppt.: HC1 or chlorids: curdy ppt. insoluble in boiling HN0 3 , but in- stantly soluble in dilute NH 4 HO (1 to 20); hypochlorites give same reaction, with odor of Cl. 1 Find metal or metals present before testing for acid radicals ; then test for the salts of the metal known to be soluble. If O (evaporated) does not char on heating with H y S0 4 , no organic acids or salts except H 2 C 2 O 4 can be present. 266 ANALYSIS. HBr or bromids: dirty-white ppt., insoluble in HNO 3 , slowly sol- uble in strong NH 4 HO (not in dilute). HCN or cyanids: curdy ppt. with bitter-almond odor, sparingly soluble in NH 4 OH, in strong boiling HNO 3 , but not in dilute HNO 3 ; does not blacken on exposure to light, as chlorid and bromid do. Ferrocyanids : gelatinous ppt., dissolved by NH 4 OH; ferric solu- tions give a dark-blue ppt., insoluble in HC1. Sulphocyanid: turns blood-red on adding a ferric solution. Light yellow = HI or alkaline iodids: ppt. does not dissolve in hot HN0 3 and is practically insoluble in NH 4 OH. Black ppt.: H 2 S or sulphids: sewer-gas odor often noticeable on treating with a mineral acid. HCHO 2 and formates: metallic Ag separates on boiling. HC 3 H 5 3 and lactates: dark ppt. on boiling, leaving a blue liquid on subsidence. Neutral reaction: White ppt.: H 2 SO 3 and sulphites: turns black on heating. H 2 C0 3 and carbonates: effervesce with cold acids generally, evolved gas turning lime-water milky. H 3 BO 3 and berates: ppt. soluble in HNO 3 or NH 4 OH; green flame on igniting with alcohol in case of solid acid. H 2 C 2 4 and oxalates: soluble in NH 4 OH and in hot concentrated HN0 3 ; acid decolorizes K 2 Mn 2 O s solution. H 2 C 4 H 4 O 6 and tartrates: turns black on boiling; silver mirror on warming mixture after adding just enough NH 4 OH to dissolve ppt. H 3 C 6 H 5 O T and citrates: no mirror of Ag on boiling; both this and that above char on heating in solid form. H 3 PO 3 and phosphites: turn black, from metallic Ag. Hypophosphites : soluble in excess: turns yellow, brown, and black (reduction). heated with HgCl 2 yields calomel, then black Hg. Meta- and pyro- phosphates: soluble in HN0 3 and in NH 4 OH. Thiosulphates : white ppt. on adding excess of reagent soon turns yellow, brown, and black (Ag 2 S), more quickly on heating. Yellow ppt.: H 3 P0 4 and phosphates: lemon-yellow ppt. soluble in HNO 3 and in NH 4 OH. O gives with solution of (NH 4 ) 2 Mo0 4 in HN0 3 a yellow ppt., which is insoluble in HNO 3 , but soluble in NH 4 OH. H 3 AsO 3 and arsenites: canary-yellow ppt. with argent-ammonium nitrate, soluble in excess of NH 4 OH or HNO 3 . Reddish ppt.: H 3 AsO 4 and arsenates: brick-red ppt. H 2 Cr0 4 and chromates: dark-red ppt., soluble in HN0 3 and in NH 4 OH. Ferricyanids : orange ppt. O + ferrous solutions gives a dark- blue ppt., insoluble in acids. BaCl 2 , Reagent: Neutral or alkaline reaction: White ppt.: H 2 SO 4 and sulphates: insoluble in boiling H 2 O and in boiling HNO 3 ; strong H a S0 4 chars organic substances. FINDING THE ACID. 267 H 2 SO 3 and sulphites: white ppt. produced on boiling with BaCl 2 and Cl water or HN0 3 (forms sulphate). H 2 CO 3 and carbonates: soluble in HC1 with effervescence. H 3 P0 4 and phosphates: soluble in acetic and all stronger acids. tUC 2 4 and oxalates: insoluble in HC 2 H 3 2 ; soluble in HC1, HNO 3 , or NH 4 C1. H 3 B0 3 and borates: soluble in excess of water, in HC1, or NH,C1. Turmeric paper turns brown-red on drying, after dipping in hot solution of acid (borates must first be rendered just acid with HC1). H 2 C 4 H 4 O 8 and tartrates: soluble in NH 4 salts or in HC1. H 3 AsO 4 and arsenates (see special tests for As). Thiosulphates: soluble in excess of water, and decomposed by HC1 with pptn. of S. Yellow ppt.: H 2 Cr0 4 and chromates : ppt. soluble in HNO 3 , insoluble in HC 2 H 3 2 . Reagent: Neutral or sliyhtly acid: Yellowish ppt.: H 3 PO 4 and phosphates: light-yellow, gelatinous ppt. in presence of NaC 2 H 3 O 2 . Avoid excess of Fe 2 Cl e . H 2 C 2 O 4 and oxalates: soluble in HC1 or HNO 3 . H 3 BO 3 and borates: turmeric test (see under BaCl 2 ). H ;j AsO 4 and arsenates (see special tests). H 2 CO 3 and carbonates: yellowish-brown Fe 2 (HO) 6 ; CO 2 escapes. Reddish ppt.: HC 7 H 5 O 2 and benzoates: flesh-colored or reddish-white ppt. (in slightly alkaline medium), soluble in acids, including benzoic. HC 2 H 3 2 and acetates : reddish-brown coloration, pptg. on boiling ; color discharged both by HC1 and HgCl 2 . Sulphocyanids : blood-red coloration, not destroyed by dilute HC1, but disappears on adding HgCl 2 . Pyrogallic acid (C 6 H 6 O 3 ) : red solution. H 2 C 7 H 2 O 7 and meconates: red color, not discharged by HgCl 2 nor by dilute HC1. Black ppt.: H 2 S and sulphids: disgusting characteristic odor evolved on treat- ing with HC1. HC 14 H 9 O 9 and tannates: bluish black or greenish black, dissolved in excess of tannin, decolorized by HC1 or H 2 C 2 O 4 . Blue or violet ppt.: Ferrocyanids : dark Prussian blue, decomposed by alkalies (red- dish brown), insoluble in acids (restore blue color after treat- ing with alkalies). Thiosulphates ("Hyposulphites") : reddish violet, gradually dis- appearing by spontaneous reduction. C a H B OH and carbolates: permanent reddish-violet color. O + excess of Br water gives white ppt. (tribromphenol). HC 7 H 5 O 3 and salicylates: deep-violet coloration. Brownish: ferricyanids : brownish coloration, changed to blue ppt. on adding reducing agents (H 2 SO 3 or SnCl 2 ). CaCl 2 , Reagent: Neutral or alkaline: White ppt.: H 2 SO 4 and sulphates: ppt. best secured by adding a half-volume 268 ANALYSIS. of alcohol and shaking; ppt. dissolves readily in dilute HN0 3 or HC1, as also in saturated solution of KN0 3 . Na,S 2 O 3 , or NH 4 salts. H 2 SO 3 and sulphites: O + strong acid yields odor of S0 2 . H 2 CO 3 and carbonates: soluble in NH 4 C1, and in acids with effer- vescence. H 3 PO 4 and phosphates: soluble in acetic and all stronger acids. H 3 BO 3 and berates: soluble in HC 2 H 3 O 2 and stronger acids, and in slightly alkaline solutions (NH 4 OH) or in NH 4 C1. H 3 AsO 4 and arsenates (see special tests for As). H 2 C 2 O 4 and oxalates: soluble in HC1 or HNO 3 , insoluble in HC 2 H 3 O 2 . H 2 C 4 H 4 O 6 and tartrates: soluble in KHO, redeposited on boiling; also dissolved by HC 2 H 3 O 2 . H 3 C B H 5 7 and citrates: white ppt. on boiling, soluble in NH 4 C1 (not in KHO) and redeposited on boiling. HgCL, Reagent: Neutral, alkaline, or acid: White ppt.: Bicarbonates of K, Na, and Li: effervesce with acids. Hypophosphites : slightly acidulated with HC1, give a white ppt. of calomel, turning dark on heating. Reddish-brown ppt. = carbonates of K, Na, and Li; effervesce with acids. FeS0 4 , Reagent: Neutral reaction: Dark-brown ppt.: HN0 2 and nitrites: best shown as a dark ring by contact method disappears on heating. HNO 3 and nitrates : in presence of H 2 S0 4 , dark coloration -as with nitrites. White ppt. = f errocyanids : changes quickly to blue. Blue ppt. f erricyanids : ppt. insoluble in acids; deposits dirty- green Fe(HO) 2 when boiled with KHO. DETECTION AND SEPARATION OF MIXED SALTS. If the student will bear in mind the reactions for the separate salts, he will have little difficulty in deducing methods for differentiating mixtures of salts. The following notes will serve as illustrations: 1. To Separate Chlorids, Bromids, and lodids. All three give a light-colored ppt. with AgN0 3 . This ppt., washed on a filter and per- colated with dilute NH 4 HO (1 to 20), will show in the percolate any chlorid by repptn. with HN0 3 . The remaining deposit on the filter-paper may be treated with strong NH 4 HO, which dissolves out any bromid (repptd. with HN0 3 ), leaving Agl as a light-yellow residue. A mere cloud on adding the acid should be disregarded. 2. To Detect Bromids in Presence of lodids. A blue color, pro- duced on adding very little starch solution and a drop or two of Cl water, shows an iodid. On adding more Cl water the blue color is dis- charged, when, if any bromid is present, it is revealed by a yellow color on snaking with chloroform. SEPARATION OF SALTS. 269 3. To Separate Chlorids from Chlorates. All the chlorid is pptd. with excess of AgNO 8 and filtered out. The filtrate is acidulated with H 2 SO 4 and a fragment or two of zinc dropped in, when if a chlorate is present it will be reduced to chlorid and give a second ppt. on adding AgNO,. 4. To Separate Sulphids, Sulphites, and Sulphates. Pour solution on excess of CdCO 3 , digest at a gentle heat, filter, and dissolve uncom- bined carbonate in HC 2 H 3 O 2 . A yellow residue on the paper indicates a sulphid. The filtrate may contain sulphite and sulphate, to separate which add BaCl 2 , filter out ppt., and boil with a little HC1, which dis- solves out BaSO :! with evolution of SO 2 and leaves the insoluble BaSO 4 . 5. To Separate Chlorids, lodids, and Bromids from Nitrates. Ag 2 SO 4 ppts. the halogens and leaves the nitrate in solution. 6. To Separate Chlorids from Cyanids. Both are pptd. by acidulat- ing slightly with HN0 3 and adding excess of AgNO 3 . The cyanid in the ppt., after washing thoroughly with boiling water by decantation, is dis- solved in boiling HNO 3 , leaving the insoluble chlorid. HC1 is added to the acid solution, throwing down a white ppt. cyanid changed to chlorid. 7. To Separate Ferrocyanids from Ferricyanids. The ferrocyanid is pptd. with excess of Fe 2 Cl c , after acidulating with HC1. The super- natant brownish liquid also gives a blue ppt. when heated with a little zinc amalgam (reduction) if ferricyanid is present. 8. To Detect Cyanids in Presence of Ferrocyanids and Ferri- cyanids. The latter two salts are pptd. by acidulating slightly with HNO 3 and warming gently with ferric and ferrous sulphates. When a blue color is produced in some of the supernatant liquid by adding excess of KHO and then acidulating with HC1, a cyanid is also present. 9. To Detect a Phosphate in Presence of Iron. Dissolve in as little HC1 as possible; add some H 3 C 6 H 5 O 7 and then excess of NH 4 HO. From this solution, when cold, magnesia mixture (1 part each of NH 4 C1, NH 4 OH, and MgSO 4 in 8 parts of water) ppts. white crystals of NH 4 - MgP0 4 . 10. To Detect a Phosphate in Presence of Alkaline Earths (Mg or Mn). Dissolve in water with the aid of as little HN0 3 as possible, then add excess of NH 4 C 2 H,0 2 to remove any excess of HNO 3 ; on adding a drop or two of Fe 2 Cl 6 and warming, a white ppt. of Fe 2 (P0 4 ) 2 is formed. 11. To Detect Carbolic in Presence of Salicylic Acid. Add 1 m. each of saturated solution of KHCO 3 , and anilin, and 5 m. of solution of chlorinated lime, when a deep blue is produced if carbolic acid is present. 12. To Separate Oxalates, Tartrates, and Citrates. Make slightly alkaline with NH 4 OH, add CaCl,, allow to stand for ten minutes, and filter. Filtrate may contain citrate; on boiling gives slow, white ppt. on sides of tube. The ppt. may contain oxalate and tartrate: acetic acid dissolves the latter, not the former. The tartrate filtrate gives a white ppt. on adding NH 4 OH to render slightly alkaline, and on further addition of AgNO 3 and boiling yields a silver mirror. PYROLOGY. An ordinary gas-, candle-, or spirit- flame consists of three parts, namely: an inner dark nucleus, a middle luminous cone or mantle, and an outer bluish sublumjnous mantle. The first 70 ANALYSIS. portion is composed of a mixture of unoxidized gases; the sec- ond of partially oxidized gases (especially C 2 H 4 and CH 4 ), the excess of C in solid particles reflecting the light from all points and thus making this stratum the most luminous; in the third, or outer part, which is most exposed to the of the atmos- phere, combustion is nearly complete, hence the flame is only feebly luminous. The Bunsen flame is hotter and less luminous than others, because air is mixed throughout the gases instead of combining merely on the surface, as in ordinary combustion. The hottest Fig. 39. Bunsen Flame. part of the Bunsen flame is the bright spot at the apex of the zone of fusion between its two mantles (4000 F.); hence sub- stances to be fused should be held at this point. H burning in furnishes 34,462 thermal units; C in 0, 8080 units. Experiment. Close the Bunsen jet at the bottom, and by means of a small glass tube prove that the nucleus of the flame consists of unburned and combustible gases. The blow-pipe is an instrument much used in metallurgy and analysis. It consists of a metal tube with a narrow nozzle, through which a continuous current of flame can be passed into PYROLOGY. 271 the Bunsen flame. The blow-pipe flame has two parts: an inner bluish reducing, and an outer yellowish oxidizing; the tip of the inner cone is best for reduction. Blowing across the flame with the blow-pipe lengthens and narrows the flame, thereby increasing the sphere of combustion and the degree of heat, and concentrating the latter within narrower limits. In pyrology, or analysis by fire, there are two general Fig. 40. Oxidizing Blow-pipe Flame (Light Blue). processes: oxidation and deoxidation (reduction). For oxidiz- ing purposes the flame is lowered and the blow-pipe pushed into it with a fair current, in order to secure free admixture with 0. The substance to be oxidized is held in the tip of the outer mantle a little beyond the apex of the luminous cone. For re- ducing powders to the metallic state, a stronger flame and a Fig. 41. Reducing Blow-pipe Flame (Yellow). weaker current are employed; the blow-pipe is held just on the border of the flame, the substance to be deoxidized just within the luminous apex: i.e., the part of the flame deficient in 0. For analytic purposes the powder is mixed with about twice as much Na 2 C0 3 , and the mixture is placed in a hollow on a piece of charcoal. Experiment. Oxidize powdered zinc. Experiment. Reduce BiONO 3 to metallic bismuth. 272 ANALYSIS. BLOW-PIPE ANALYSIS. I. Heat on asbestos or charcoal before blow-pipe. No residue ordinary alkaline salts: fuse and sink into charcoal. Residue: Shining white: Moisten, when cold, with a drop of Co(N0 3 ) 2 and use blow-pipe again. Blue = Al or borates, phosphates or silicates. Green = Zn. Pale-rose or flesh colored = Mg. Colored: Use borax bead. II. Mix with twice as much Na 2 C0 3 , and heat on charcoal in reducing flame. Metallic globules or powdered mass: With surrounding incrustation of oxid: Yellow : Bi: brittle bead, with pink tinge, easily fusible. Pb: soft, gray-white, malleable; marks paper; border of white carbonate. Sn: white bead, very oxidizable and fusible. White: Sb: gray, very brittle, readily oxidized and volatilized (white fumes) ; bead skips about when dropped, leaving a white trail. No surrounding incrustation: Ag: clear, white malleable bead; does not oxidize readily. Cu: red, tough, malleable; colors flame green. Fe: reddish magnetic powder (Fe 3 O 4 ). Co: light- or dark- blue mass, according to amount. Ni: violet when hot, cooling yellowish brown. Mn: green mass of manganates on fusing on Pt with Na 2 C0 3 and KNO 3 . Cr: yellow mass when treated like Mn. Au: bright-yellow bead. Pt: gray, infusible powder Only incrustation (metals volatilize): White = As: garlicky smell. Yellow, cooling white = Zn: may be greenish-white mass in center. Reddish-brown Cd. 2Vo globules or incrustation = Hg. VOLATILIZATION TESTS. Mix powdered substance with a little charcoal and Na.,CO 3 , place in a small dry test-tube, and heat, watching for shiny metallic mirror or sublimate on cooler part of tube. Mercury: minute gray globules. Arsenic: gray-black sublimate. Antimony: similar to As, but lighter-colored. Sulphur: yellow sublimate. Ammonium compounds: NH 3 given off recognized by odor and action on moist litmus-paper. Water and hydroxids: steam. QUANTITATIVE ANALYSIS. 273 BORAX-BEAD TESTS. On heating sufficiently borax loses its water of crystalliza- tion, fusing into a glassy substance called a bead. Borax beads have great avidity for oxids, and with the blow-pipe give char- acteristic colors in the oxidizing and reducing flames for cer- tain metals, as shown by the following short table: METAL. OXIDIZING FLAME. REDUCING FLAME. Co Blue. Blue. Cr Green. Green. Cu Green, cooling blue. Red (cold). Fe Red, cooling yellowish. Bottle-green. Mn Amethyst. Colorless. Ni Red-brown, cooling yellow. Red-brown, cooling yellow. FLAME TESTS. Dip loop of Pt wire in HC1 (to form more volatile chlorid), then catch up a little of powder or concentrated solution and hold in outer, colorless flame near base. The following metals each give a character- istic color to the flame: Violet = K: look through blue glass to shut out yellow colors; NH 4 compounds and organic matter also give a faint-violet color. Yellow = Na: color intercepted by blue glass. Reddish yellow = Ca. Greenish yellow Ba or Mo. Green Cu or boric or phosphoric acid. Blue = Pb, As, Sb, Bi, CuCl 2 . Crimson = Li (not pptd. from solutions by NH 4 compounds) or Sr (pptd. from solution by [NH 4 ] 2 CO 3 in presence of NH 4 OH and NH 4 C1). QUANTITATIVE ANALYSIS. Quantitative determinations are, in general, either gravi- metric or volumetric. Gravimetric methods consist simply in drying and weighing the various ppts. obtained separately as described heretofore. Precipitation should be complete, as shown by the reagent giving no further ppt. after subsidence. Knowing the chemic composition of the ppt., the amount of each element in it and the weight of the original substance in solution are readily calculated (see "Stoechiometry"). The amount of substance taken to be analyzed, if in the solid state, should rarely exceed a gram. All the ppt. (usually best obtained in a beaker, avoiding excess of reagent) is collected by filtration on a small circle of filter-paper (Swedish No. 2 is best), is well washed with dis- tilled water, and then dried by placing filter and contents in a drying oven at 100 C. The dry powder, if inorganic, is then transferred from the paper to a tared crucible, the folded paper 274 ANALYSIS. (containing particles of ppt.) is incinerated on the lid of the crucible over the flame, and the ash is removed to the crucible, which is now heated until all moisture is expelled. After cool- ing in a desiccator (a closed vessel containing a dish of H 2 S0 4 ), the crucible and its contents are weighed, and the weight of the crucible alone and of the filter-ash (previously determined by weighing others, or stated on each package) deducted. Or- ganic ppts. generally and some inorganic, like K 2 PtCl 6 , are col- lected on a previously dried and weighed filter, well washed, dried at 100, then weighed; the weighing each time is best done between two watch-crystals held together by clamps. It should be borne in mind that ignition often changes the character of a ppt.; thus, oxalates become carbonates; hydrox- ids, oxids; and phosphates, pyrophosphates. The water of crystallization is estimated by heating a gram or so of the salt in the air-bath at from 120 to 300 until no further loss in weight takes place. The carbonic acid of carbonates is gen- erally determined by treating with dilute HC1, and calculating the loss as C0 2 . In the wet methods of quantitative analysis it is particu- larly necessary to throw down all of a given compound by add- ing the reagent drop by drop to the solution, with shaking or stirring and sometimes warming, until no further ppt. is pro- duced. After this the mixture should stand for a few minutes to allow complete precipitation to take place. The ppt. on the filter should be well washed, as a rule, by means of a jet of distilled water from the wash-bottle, saving the washings with the remainder of the filtrate for the next reagent. Cloudy washings can usually be prevented by allowing the deposit on the filter to drain dry before washing. Filtration is aided by conducting the clear supernatant liquid down a glass rod from the lip of the beaker on to the filter before washing the ppt. out of the beaker. In the use of the analytic balance and weights care should be taken never to put any chemical directly on the pan, but in a clean tared crucible or watch-crystal; to use forceps, not fingers, for lifting weights; to keep the beam off the knife- edges when making any transfer; to weigh corrosive substances in stoppered tubes; and to keep dust out of the instrument as much as possible. Careful notes should be taken of each step and a systematic record kept for final calculations and future reference. Experiment. Weigh out 1 gm, of BaCl 2 .2H 2 O, dissolve in 100 c.c. of water, ppt. Ba with dilute H 2 SO 4 , dry and weigh ppt., and reckon from this weight that of the chlorid first taken. QUANTITATIVE ANALYSIS. 275 The volumetric method is very rapid and convenient, and consists essentially in adding to a substance in solution from a buret (titration) a standard solution of the reagent until the reaction is just completed, as shown by color-changes in the substance tested or in some other substance added as an indi- cator. Graduated flasks or beakers and pipets are also utilized in this method. Standard solutions are either normal or empiric: that is, arbitrary, as Fehling's solution, which is so constituted that 1 c.c. is completely reduced by 5 mg. of dextrose. All normal solutions are chemically equivalent to each other in equal volumes. They are prepared by dissolving in a liter of distilled water the weight in grams of a molecule (gram- molecule) of the substance (including water of crystallization) in the case of monovalent substances (monacid or monobasic); one-half the gram-molecule in the case of substances combin- ing in the divalent role [H 2 S0 4 , Na 2 C0 3 , Ca(HO) 2 ]; and one- third the gram-molecule of substances whose hydrogen equiv- alence of the positive and the negative ions is 3. By the stand- ard or titer of a volumetric test solution is meant its strength per liter or cubic centimeter. A normal solution is expressed briefly as N / x . More delicate results are obtained by diluting normal solutions 10 to 100 times, the resulting solutions being designated as N / 10 (decinormal) or N / 100 (centinormal). Volumetric methods are of three general types: direct, indirect, and residue. The neutralization of an acid with an alkali is an example of the first; the liberation of Cl from HC1 by boiling with Mn0 2 and the estimation of the Cl with KI as liberated I by means of Na 2 S 2 3 is an example of the second; the estimation of CaC0 3 by difference on treating with a normal acid solution, which is afterward titrated with alkali to determine the loss of acidity, is an example of the third class. The chief general processes included under volumetric titration are neutralization (acidimetry and alkalimetry), oxida- tion (dichromates, permanganates), reduction (ferrous salts, H 2 C 2 4 ), precipitation, and iodimetry (estimation of I with Na 2 S 2 3 ). The principal color-changes are in litmus (from red to blue for neutralization of acids, and vice versa), phenol-phthal- ein (1-per-cent. solution in dilute alcohol: pink with alkalies, colorless with acids), cochineal or rosolic acid (yellow with acids, violet with alkalies; used chiefly for NH 3 and JSTH 4 compounds), methyl orange (0. 1-per-cent. aqueous solution: yellow with hydrates, carbonates, and bicarbonates; orange-red with acids), 276 ANALYSIS. starch solution (blue with I), K 2 Cr0 4 (red color with Ag salts), and ferric alum (brown-red with KSCN"). A few drops of these solutions are added to the substance to be tested, also in solution in a beaker or flask. K 2 Mn 2 8 gives off 0, and is decolorized on heating with organic sub- stances in an acid solution. Cr0 3 , on- reduction, changes from orange to green. The basis for normal acid solutions is oxalic acid, which is chosen because it does not contain a variable quantity of non-crystalline water, as is the case with the common mineral acids. The full formula of crystallized oxalic acid is H 2 C 2 4 .- 2H 2 0; hence the molecular weight is 125.7. Being dibasic, one-half this weight, or 62.85 gm. of the acid, is dissolved in sufficient distilled water at 15 to make a liter. The basis for normal alkali solutions is Na 2 C0 3 , of which 52.92 gm., or half the gram-molecule, is dissolved in water and diluted to a liter. Other normal alkali solutions (KHO, NaHO) are obtained by dissolving approximately the H equivalence (one-half or the full molecular weight in grams) of the sub- stance in about 1000 c.c. of water, then titrating with normal acid and diluting with water until 10 c.c. of the acid solution is exactly neutralized by 10 c.c. of the alkali. Other normal acid solutions than oxalic are standardized by means of a nor- mal alkali solution. In titrating carbonates with normal acid, the alkaline solu- tion should be boiled toward the end of the reaction in order to drive off C0 2 , which has an acid reaction on litmus and phe- nol-phthalein, but not on methyl orange. Alkali salts of the organic acids are first converted into carbonates by ignition before titrating with acids. Acids neutralize bases (including oxids, carbonates, and organic salts after ignition), and bases neutralize acids or acid salts (such as KH 2 P0 4 ). For example: 39.96 36.37 58.37 17.96 NaHO + HC1 = NaCl + H 2 As shown by the molecular weights with the above equa- tion, 1 c.c. of any normal solution is equivalent to 1 c.c. of any other for which it is a test, and the exact weight of any acid or alkali in solution is readily found by neutralizing with a normal or decinormal alkali or acid, and multiplying the number of c.c. used of the latter by the weight in mg. of 1 c.c. of a normal solution of the substance tested. The following table of com- mon neutralization equivalents in grams is convenient for refer- ence: QUANTITATIVE ANALYSIS. 277 ONE C.C. OF NORMAL ACID is ONE C.C. OF NORMAL ALKALI is EQUIVALENT TO EQUIVALENT TO Ammonia 0.01701 Acetic acid 0.05986 Ammonium carb. (U.S. P.) 0.05226 Citric acid 0.06983 Lead subacetate 0.13662 Hydrobromic acid 0.08076 Lithium carbonate .... 0.03693 Hydrochloric acid 0.03637 Potassium bicarbonate . . .0.09988 Hydriodic acid 0.12753 Potassium carbonate .... 0.06895 Hypophosphorous acid . . . 0.06588 Potassium hydroxid .... 0.05599 Lactic acid 0.08989 Potassium permang 0.03153 Nitric acid 0.06289 Pot. sodium tartrate . . . .0.14075 Oxalic acid 0.06285 Sodium bicarbonate .... 0.08385 Phosphoric acid (K 2 HPO 4 ) . 0.04890 Sodium borate 0.19046 " (KH 2 PO 4 ) . 0.09780 Sodium carbonate 0.05292 Potassium dichromate . . .0.14689 Sodium hydroxid 0.03996 Sulphuric acid 0.04891 Strontium lactate 0.13244 Tar taric acid . ... .0.07482 The pharmaceutic practice of volumetric work is to weigh out such an amount of the substance for analysis that the num- ber of c.c. of the normal solution used will express the per- centage. Thus, 3.64 gm. of United States Pharmacopeia dilute HC1 containing 10 per cent, of the anhydrous acid is exactly neutralized by 10 c.c. of normal alkali. Alkaloids can be estimated volumetrically by dissolving in a measured amount of N / 20 HC1 and determining the excess of acid over that which combines with the alkaloid, by means of N /2o NaHO, using phenol-phthalein as an indicator. Each c.c. of the N / 20 acid is equivalent to the following gram factors of alkaloids: Aconitin 0.0323 Coniin 0.0062 Atropin 0.0144 Morphin 0.0142 Brucin 0.0197 Nicotin 0.0040 Cinchonin 0.0147 Quinin 0.0162 Cocain 0.0151 Spartein 0.0028 Codein 0.0149 Strychnin 0.0167 Mayer's solution, or the decinormal potassium mercuric iodid solution, contains 39.2 gm. of this salt per liter, and is made by dissolving 13.546 gm. of HgCl 2 in 600 c.c. water and 49.8 gm. KI in 100 c.c. water, mixing the two solutions and diluting up to 1000 c.c. This solution is used in estimating some of the alkaloids, which should be distinctly acidified (not with HCoH^O;,) before running in the reagent. The end of the reaction is shown when the reagent produces a ppt. with a few drops of clear filtrate; an excess should be avoided. The ppts. formed by Mayer's reagent are compounds of the base with one 278 ANALYSIS. or more molecules of HI and HgI 2 . The following equivalents have been determined experimentally for each c.c. of the deci- normal solution: Aconitin 0.0269 Morphin 0.0200 Atropin 0.0097 Narcotin 0.0213 Berberin 0.0425 Nicotin 0.0040 Brucin 0.0197 Physostigmin 0.0137 Cinchonin 0.0102 Quinidin 0.0120 Coniin 0.0125 Quinin 0.0108 Emetin 0.0189 Strychnin 0.0167 Hyoscyamin 0.0069 Veratrin 0.0296 Oxidimetry is accomplished by means of potassium per- manganate, K 2 Mn 2 8 (315.34), which gives off 5 atoms of in the presence of H 2 S0 4 and organic matter: K 2 Mn 2 8 + 3H 2 S0 4 == K 2 S0 4 + 2MnS0 4 + 50 + 3H 2 A normal oxidizing solution is one which will liberate as much per liter as is equivalent to 1 gram-atom of H, namely: 1 / 2 gram-atom, or 8 gm. of 0, since it takes 2 of H to combine with 1 of 0. A normal solution of K 2 Mn 2 8 therefore con- tains V 10 its molecular weight ( 1 / 2 -=- 5), or 31.534 gm. per liter. It is standardized by means of normal (or decinormal) oxalic-acid solution, equal volumes of which completely decol- orize the permanganate solution. The equivalence of normal K 2 Mn 2 8 for different substances is obtained by studying the equations representing their reactions. For example: KN0 2 -j- = KN0 3 . Nitrites take up 1 atom of 0, equivalent to 2 liters of N / K 2 Mn 2 8 . . the equivalent factor of: TT-vro 39.03+14.01+31.92 84.96 _ n fMo^o JS.1MJ 2 2x1000 - 2000 U-U4^40 The decinormal equivalent is 0.004248. In estimating Fe and its compounds with K 2 Mn 2 8 , ferric compounds must first be reduced to ferrous by heating in a flask with nascent H (Zn + H 2 S0 4 ). The following are the most important equivalences of 1 c.c. of decinormal K 2 Mn 2 8 : Barium dioxid 0.008441 Hydrogen dioxid 0.001696 Ethyl nitrite 0.003743 Hypophosphorous acid . . 0.001647 Ferrous carbonate 0.011573 Oxalic acid (cryst.) 0.006285 Ferrous oxid 0.007195 Oxygen 0.000798 Ferrous sulphate 0.015170 Potassium hypophosphite. 0.002598 Ferrous sulphate (cryst.) . 0.027742 Sodium hypophosphite . . 0.002646 lodimetry depends on the reaction between I and Na 2 - S,0,:- 21 + 2Na 2 S 2 3 = 2NaI + Na 2 S 4 6 SPECIAL METHODS. 279 Normal solutions of both these substances are used with starch solution (1 gm. of starch in 200 c.c. of boiling water) as an indicator of uncombined I. The thiosulphate is also em- ployed for the volumetric determination of Cl and of ferric salts through the agency of KI, free I being liberated. Deci- normal I solution is made by dissolving 12.653 gm. of I in a solution of 18 gm. of KI in 300 c.c. of H 2 and diluting to a liter. Sodium thiosulphate contains 5 molecules of water of crystallization; hence its normal solution is made to contain 247.64 gm. of the salt per liter. Decinormal AgN0 3 solution (16.955 gm. per liter) is used for the direct estimation of haloid salts and acids. Normal K 2 Cr0 4 is used as an indicator, forming permanent red chro- mate of silver as soon as all the chlorid, bromid, and iodid has been pptd. Copper is generally estimated volumetrically by a standard solution of KCN, made by dissolving 60 gm. of KCN in a liter of water, the solution to be kept in a dark place in a glass- stoppered bottle. Then weigh out 0.25 gm. of pure Cu foil or wire, place in a beaker, and add 10 c.c. each of HN0 3 and H 2 0, and boil till all the Cu is dissolved and brown fumes cease to appear. Transfer the solution and beaker washings to a 100 c.c. flask, dilute to the mark, and shake thoroughly. Take half of this in a beaker, add slight excess of NH 4 OH and run in the KCN solution until the blue color is changed to a faint pink. Eepeat the standardizing process with the other half of the Cu solution, and take the average of the two findings. Compute the equivalence factor by dividing 0.125 by the number of c.c. of KCN used to decolorize the Cu solution. Thus, if it takes 20 c.c. of KCN to remove the blue color, then the factor is: 0.125 -=-20 = 0.0062 SPECIAL METHODS AND APPARATUS. ARSENIC TESTS. If dissolved in stomach-contents, separate from colloids by dialysis, and destroy all organic matters by boiling for some hours with addition of HN0 3 , and filtering. The chemicals and dishes used must first be proved free of arsenic by blank tests. 1. Ignite on charcoal with blow-pipe and note garlicky odor. 2. Heat a small quantity in a reduction tube with Na 2 CO 3 and KCNj observe dark metallic mirror in upper part of tube, due to As. 280 ANALYSIS. On breaking off lower end of tube and heating again, we get a crystal- line mirror of As 2 O 3 . 3. Fleitmann's Test. Boil a small piece of Al with KHO: Al, + 2KHO + 2H 2 O = K 2 A1 2 4 + 3H 2 In presence of As H s As is formed, reducing AgNO 3 (white filter-paper dipped in strong solution and held over mouth of tube) to black, shining, metallic Ag. Sb does not react to this test at all. 4. Keinsch's Test. The arsenic solution acidulated with one- seventh as much HC1 deposits a blue-gray film of As (or Sb, Hg, or Bi) on Cu foil with the aid of heat. Wash foil in water, dry with filter-paper, and heat in wide, dry test-tube. Note crystalline deposit in upper part of tube. Break tube and examine crystals of As.Os under microscope. They are octahedral rhombic prisms if cooled rapidly. Blank test: the Cu and acid must show no stain on prolonged boiling with distilled water. Fig. 42. Apparatus for Detection of Minute Amount of Arsenic. 5. Marsh's Test. Prepare nascent H from pure Zn and dilute H 2 SO,; after a few minutes ignite and show that no stain is produced by the flame on a white porcelain surface. Then add suspected solution. If As is present, the color of the flame changes to a light blue (As 2 3 fumes) characteristic of H 3 As, and a dark metallic stain is left on a white porcelain surface by touching it to the flame. This stain may be either metallic As or Sb. To distinguish between the two (As is soluble in NaCIO solution) dissolve the spot in a drop of HN0 3 , evaporate gently (As is volatile), and apply a drop of a strong solution of AgN0 3 , which gives with As a brick-red mark due to Ag 3 AsO 4 ; the stain exposed to H 2 S turns lemon-yellow. The tube through which the H 3 As passes, when heated to a dull-red heat, shows a mirror, in the cooler part, of metallic As. Extinguish the flame and dip delivery tube into AgN0 3 ; on running NH 4 HO over the latter fluid a yellow ring appears at the junction of the two fluids. Marsh's is the most delicate test known for As and its com- pounds, showing, it is said, as small a proportion as 1 part in 200,000,000. Unfortunately it is inconclusive in the presence of organic matter, which can, however, be destroyed by oxidizing with HN0 3 or with KC10 3 and HC1. PLATE II. s ;/ r '-^ U '* Fig. 3 fin. "~s >< to B fi" 6^ 1 o o 2 || A | *> o ^ i* c ? a i TLo 5 ' 3'C 2 * 'C u 1 ^ j o pd fcr-s .C - *-"_S HoSO4 COLOR-TESTS : 1 OR TO 20 DROPS OF Oi co c ^ .-s g "s a> > V M s^ 1 u-s g 1-1 |i ^ Q pq Greenish yellow to mottled on stirri II 11 I 1 i! 1.1 2 W 3 d 0) 2 tJD Brown. * S a! 1?^ S 1 1 CO CC C^ u o^5 3 3 3 00 rH 3 CO 3 3 CO ill (N (N CO CO CO rH 8 -CJ o 1O ON ' S M fcg 55 CC CO oo S "* 33^ 3 3 O 3 1 3 ; O ^ CO 3 3 II r* C* O 1 CC CO o ^ , 1 _j_ t s 3 1 * | 1 H ' o o D ^ J^- CC !>. Tf Q "*^ C 5 Oi O5 O^ Ct s O5 o S d d c :> ^ d d d LO d d d O d 3 3 ffi , i 2 3 3 3 O5 3 3 3 3 3 DJ O S S s S O5 O5 ~T C i 3 S 8 ^ Gi Gi Oi d 1 1 O5 05 1 A d do5d BO d d d d d d d O5 00 d d M S : : s x -g : ^ ' i : . - S 1 | 1 S to ^ jS C 03 i _ ^ > c d ^ ' ^ rrt i is >>= *J (_, -w !_ 3 I Its,' 5 |. - II (H - C o 03 1-3 A II l & 5S 290 ANALYSIS. OTHER REACTIONS AND TESTS. ilute solution touched to tongue causes numbness and tingling. a. 2 CO 3 ppts. white alkaloid ; soon turns green and colors chloroform blue or violet. r eak solution dilates pupil ; Au- C1 3 gives a yellow ppt. ed color on dissolving in HCI and a little Cl water added, resh Cl water colors brucin solution red, then violet ; de- colorized by excess. C10 3 + HCI oxidize cafFein or thein ; products turn purple- red with NH 4 OH. egative to quinin tests ; salt solutions levorotatory ; herap- athit test. egative to quinin tests ; salt solutions dextrorotatory ; phe- nol renders turbid. acal anesthetic and mydriatic. Yellow ppt. with K 2 CrO 4 , Pt- C1 4 , or picric acid. || is A 1 111 1 "S "ft ft 03 =1 uCl 3 gives a light-yellow ppt. ; CuSO 4 gives a blue ppt. 2 S0 4 -+ MnO 2 color crimson, changing to green. 11 I s o>.2_- P y 5^3 "5 60 its Q fe ? fa M fc J << B w I ^O -u' a : i - ! Ih p^ ^ Ba ^!3 sa g Greenish brown # ; +S o 8> KB i a a M* ~ "5 a "^ > ^ ^ o tH =5 ^ O SH ^ 2 *H ^ ^ Oo * ^^ac O bo 3 O |s 6a ' p ' ' ' o" a 2 1 1 * l|l -2S 1 , 1 I S S =3 2 -2 5 |P H I 1 a 1 ' tl 1^ , 3 . . 1. | i 1 ? ? 2 il : . . . 3 "3 1'? S ^ P O 1 8 w2 ^g Pi . 1 ,2 M" 54 32 r& is-g ' . 3? 3 . . l s ^ ^.2 O 3 M ft P O 3 s . 4 g a ^ a & ^fl 1 ^ P &> ^H II ? . n * 5 U^ ' E| >") O 03 S H P^ S a ! ! ! ^ H r* T3 a Aconitin Apomorp Atropin a 'i .2 .9 1 O> *H C$ PQ W O Cinchoni Cinchoni 1 Codein . Colchicin Coniiu . Gelsemin Homatro ALKALOIDS. 291 A i flx O i o O e ii r~ S 1 o . c =2 C y g g ^3 g g J* *^sj 2 -s W ^=53 ^ . 3 e^ e "S ? o * -^ b S O o >H OTHER REACTIONS AND TESTS || il a "r - 5c ;S 5 w cS cS 111 Q HNO 3 residue turns violet adding alcoholic solution K Dilates pupils. AuCl 3 gives a yellow crysta ppt., soluble in boiling acidulated with HCI. Yellow ppts. with AuCl 3 , P chromates, or picric acid duces AgNO 8 , etc. Fine red residue from evapor dilute H 2 SO 4 solution. Characteristic odor. AuCi PtCl 4 gives light-yellow pj CaClo colors red ; turns gm- heating. A trace conti pupil. Myotic and sudorific ; tritur with calomel, turns black \v breathed on. Sharp, biting sensation on h ing on tongue ; HC 2 H 3 2 + Wo 2 -recf. Solution (fluorescent) slu with Cl or Br water t bright green on adding I nw Ceroso-ceric oxid added 1 trace dissolved in a dro H 2 SO 4 shows blue, violet, Br water colors violet. | f ct = 2 "* 6G | ' =^ I'M ij j . - 1 . s -= il 2 , *o ^ ^3 ^ T3 S 0> ^33 | . "35 5 ^X! M ^ s J ^ 1 5 o 3 aj 3 3 g te c |f ' ll I'S 60 5 jl tl : 0) 11 n 3 to a c >H E 5 Hi i! 60 . . 3 J3 a .2 1 w Ss M .2 * * * s2 S * ^ i m S al E &* 5 E o | |j : : ll ll 11 1 B + > 5^ f o-?i 2 || *g : ll : ^ 1 i 53 "" * k g* O h o Sb rh ^ i O Q Yellow-red, purple hot a S^ : : |t 1 of 3 i l u | 3 a* Yellow, warm ^"1 s > ibstauce to be tes a 99 e . a . H a a S 60 a a t^ a * .2 .2 a O g. e c .s M T3 >, 111 1 1 1 I ' i tr! W K S & K CH S OF i 1 292 ANALYSIS. Wet Method. Dissolve in aqua regia (which ppts. AgCl), let settle, and pour off supernatant liquid, and add gradually to this a clear, filtered solution of FeS0 4 (5 parts for 1 of gold). Au is thrown down as a brown powder. Let settle, filter, and wash; digest deposit in dilute H 2 S0 4 , filter again, wash well, and melt powder to a button in furnace. QUESTIONS ON ANALYTIC CHEMISTRY. 1. Which is the more delicate test reagent for Pb, HC1 or H 2 S? 2. What is the black ppt. formed when NH 4 OH is added to a mer- curous solution? 3. What is the gray ppt. obtained by boiling HgCl 2 with a stan- nous solution? 4. Why cannot H 2 S be employed in a solution containing free HNO a ? How separate the silver from the copper in a dime? Fig. 45. Dental Furnace. 5. What is the object of NH 4 C1 in the third group reagents? 6. How can one obtain Cu from a solution in KCN? 7. What is the formula of the ppt. obtained by adding KC1 to a Pt solution? 8. Why does Ag. 2 CO 3 turn black on heating? 9. Explain reddish-brown change of color on treating Prussian blue with alkalies. How do acids restore the blue color? 10. Why is charcoal used for reduction tests? 11. What weight of Ca(HO) 2 in 10 c.c. of a decinormal solution of this compound? 12. Calculate the neutralizing equivalent of potassium acetate. 13. What is the brownish ppt. obtained by heating cocain with dilute H 2 SO 4 , neutralizing with KHO and adding Fe 2 Cl 8 ? 14. Mention five analytic distinctions between As and Sb. 15. How much CuSO 4 does 48 gm. of pptd. CuO represent? 16. In preparing a normal acid solution, if 10 c.c. of normal alkali neutralize 6.8 c.c. of the dilute acid, what percentage of water must be added to the latter to complete the preparation? 17. How many c.c. approximately of concentrated H,S0 4 and HC1 are required to make a normal solution of each? SPECIAL EXAMPLES. 301 Antipyrin incompatible with phenol, alum, HgCl 2 , beta- naphtol, syrup of FeI 2 , and precipitants of alkaloids. Chloral or chloralamid decomposed by alkalies, forming CHC1 3 and a formate of the alkali. Tartar emetic incompatible with tannin and antipyrin. Carbolic acid coagulates collodion. Mercuric salts coagulate albumin (soluble in excess of albumin) and gelatin, and ppt. tannin. Borax forms a gelatinous mass with acacia liquefied by adding sugar. Glucosids decomposed into glucose, etc., by free acids or emulsin. Pepsin is pptd. by many metallic salts. Pepsin and pancreatin are coagulated by strong alcohol into a flocculent rubber-like mass. Acids decompose Bi solutions. Nitrous ether darkens with tannin or tannates, liberates I from iodids, and is broken up by acids and alkalies, liberating gases very freely. It gives a green color with antipyrin; a yellow or red with acetanilid. Compound ethers are incompatible with alkalies, forming alcohol and salts. lodin or Ag 2 forms a very explosive compound with am- monium hydrate or salts; NHI 2 explodes when dry. Tincture of I is decolorized by tannin or NH 4 HO (forms NHJ). Gallic acid gives a green or brown coloration with hydrates or carbonates, blue with lime-water, bluish black with Fe 2 Cl 6 . Strong acids decompose ammonio-citrate of bismuth. Bismuth subnitrate forms a red compound with I and with salicylic acid, and liberates C0 2 in a fluid mixture with bicar- bonates. Ferric chlorid produces a violet color with carbolic and salicylic acids and their salts, creasote (quickly fades brown), .phenol radicals (salol, anilin, resorcin, cresols, guaiacol), and oils of cloves, bay, and pimenta; red color with acetates, sulpho- cyanids, antipyrin, and acacia; flesh color with benzoic acid and benzoates; green with guaiac, aloin, thallin; blue-black with gallic acid; black with tannic acid, tannates, and gentian. All reducing agents (FeSOJ ppt. gold from its solutions as a brick-red powder. Alkaloidal salts form insoluble santalates with compound tincture of lavender. 302 INCOMPATIBILITY. LIQUEFACTION ON TRITURATION. (Substances generally insoluble in water.) Antipyrin with chloral, sodium salicylate, or euphorin. Sodium salicylate with acetanilid, exalgin, etc. Chloral with camphor, menthol, phenol, or thymol. Camphor with betanaphtol, butyl chloral, menthol, phenol, thymol, and resorcin. Butyl chloral w r ith camphor, menthol, phenol, or thymol. Thymol with chloral, menthol, or phenol. Exalgin with salicylic acid. CHEMIC DECOMPOSITION ON TRITURATION. Commercial KC10 3 may explode singly under sharp con- tusion. Hypophosphites triturated alone may d Compose, forming H 3 P with explosion. lodol rubbed with yellow HgO explodes. Potassium chlorate may explode when rubbed with S, tan- nin, or picric acid. Potassium nitrate is explosive when triturated with S and dry K 2 C0 3 ; K 2 Mn 2 8 with picric acid and tannin; K 2 Cr 2 7 with tannic and picric acids. Oxid of silver should not be rubbed with dry organic sub- stances. Mercurous salts are generally reduced to metallic Hg and HgCl 2 when rubbed with other salts. This poisonous change may be prevented by moistening with a little alcohol, water, or oil before rubbing: 2HgCl + 2KBr = HgBr 2 ,2KCl (very poisonous) + Hg INCOMPATIBILITIES OF WATER. Bismuth nitrate forms insoluble basic nitrate. Water ppts. SbCl 3 as SbOCl. Subacetate of lead carbonates and forms a cloudy mixture with water which has stood in contact with the air. Mercuric salts and HgN0 3 are decomposed (except HgCl 2 ), requiring KI or free acids to effect solution. Tincture of digitalis, when mixed with aqueous or syrupy solutions, may decompose, forming new and poisonous prin- ciples. Sodium peroxid breaks up with w r ater into NallO and 0. PRESCRIPTIONS. 303 INTENTIONAL INCOMPATIBILITY. This is illustrated by black and yellow wash and by silver nitrate and acetate of lead with opium. PRESCRIPTIONS. Prescribe salts and acids with the same radical whenever practicable as tinct. ferri chloridi, liq. arsen. chloridi, acidi hydrochlorici, and hydrarg. chloridi corros. The following-named substances are best given alone in simple solution: Chlorin-water, citrate of iron and quinin, di- lute hydrocyanic or nitrohydrochloric acid, iodin, and iodids; liquors calcis, ferri nitratis, potass, and potassii arsenitis; mor- phin acetate or hydrochlorate; potassium acetate, bromid, or permanganate; qrinin sulphate; syrup of iodid of iron; tannic and gallic acids; tartar emetic; tinct. ferri chloridi and guaiaci; zinc acetate. The following combinations have been known to explode: Potassium chlorate and hypophosphites in water; potassium chlorate, tannin, and glycerin; K 2 Mn 2 8 , tincture of iron, and glycerin; HX0 3 , HC1, and tinct. nucis vomicaB; borax, NaHC0 3 , glycerin, and H 2 (evolution of C0 2 ); K 2 Mn 2 8 , alcohol, and water; oil of amber and HN0 3 ; turpentine and H 2 S0 4 ; I and spirit of camphor; O0 3 and glycerin. Mixtures of NH 4 C1 and KC10 3 have exploded violently after standing awhile. Kaolin, talcum, fuller's earth, petroleum, and paraffin are the best excipients for pills and triturates of silver salts (coated with Tolu), potassium permanganate, and dichromate. ACTION OF AIR, LIGHT, AND ATMOSPHERIC HEAT. HYGROSCOPIC AND DELIQUESCENT. ., , . EFFLORESCENT COMPOUNDS. (Not to be prescribed in cachets.) Acids: Carbolic, chromic, citric. Citric (sometimes). Aluminum: CMorid, bromid, iodid, ace- Phosphate, valerate. tate. Ammonium: CMorid, bromid, iodid, ni- trate. Amylen : Hydrate. Antimony: Chlorid. Tartrate (SbOK). Barium : Acetate. Calcium: Clilorid, bromid. iodid, Otfid, Acetate, hypoclilorite. Chloral: Hydrate and butyl. Cinchonidin: Sulphate. 304 INCOMPATIBILITY. HYGROSCOPIC AND DELIQUESCENT. (Not to be prescribed in cachets.) Cobalt: Acetate, chlorid, nitrate. Copper: Chlorid, nitrate. Ferric: Chlorid and scale compounds. Ferrous: Chlorid, bromid, iodid, phos- phate. Gold: Chlorid. Hyoscyamin: Hydrochlorate, sulphate. Lead: Lithium: Chlorid, bromid, iodid, salic- ylate. Magnesium: Chlorid, bromid, iodid, cit- rate. Manganese: Chlorid, bromid, iodid, ni- trate. Physostigmin: Sulphate. Pilocarpin : Hydrochlorate. Platinum: Chlorid. Potassium: Salts generally. Quinin: Bisulphate, sulphate, hydrochlo- rate, hydrobromate. Sodium : Hupophosphite, hydrate, haloids, nitrate. Spartein : Sulphate. Strontium: Chlorid, bromid, iodid. Strychnin : Zinc: Chlorid, bromid, iodid, nitrate. EFFLORESCENT COMPOUNDS. Sulphate. Acetate, sulphate. Ferric alum. Sulphate. Acetate. Sulphate. Sulphate. Tart rate (KNa), ferrocyanid. Carbonate. Acetate, nitrate. Sulphate. Acetate, sulphate. Granular effervescing and exsiccated salts, pepsin, codein, acid phos- phates, glycerophosphates, piperazin, lysidin, and dry vegetable ex- tracts. Color-changes. Carbolic acid turns red (just as good); resorein, pinkish, yellow,, or deep brown (especially if exposed even to traces of alkalies); apomorphin hydrochlorate, green- ish (prevented by HC1); nitric acid, bromoform, aconitin, san- tonin, and sodium santoninate, yellowish; cinchonin and cin- chonidin salts and quinin salts, brownish; permanganate solu- tions, decolorized. All Ag salts, ferrous salts (from green to bluish or reddish brown), ferric scale compounds, iodoform, HgO, Hg(CN) 2 and HgI 2 , Hg 2 I 2 , pyrogallol, syrup of garlic, oleates, and chrysarobin darken from reduction or oxidation. HCN becomes brown, then black (paracyanogen) (prevented by a little HC1). Salicylates darken in the presence of the slightest trace of alkali. Acetanilid with spirit of nitrous ether develops slowly a yellow or red color. Osmic acid blackens in contact with organic matter. Sulphurated potash oxidizes from a liver color to green, then yellow (K 2 S0 3 + K 2 S 7 4 ), and finally dirty white (K 2 S0 4 -f- K 2 S 2 3 ). Syrup of HI is reduced by light, liberating free I, with brown or yellow color (specimen unfit to use if it turns starch-paper blue). PRACTICAL EXERCISES. 305 Reduction. Ammonium salts; synthetic iodin compounds (iodoform, aristol, europhen); chinolin, lead acetate, KCN; alkaline bi-salts; zinc acetate, iodid, phosphid, and valerianate. Ferric acetate, chlorid, and nitrate become basic and insoluble. Oxidation. Hypophosphites, nitrates, sulphids, sulphites, ferrous salts, pyrogallol, tannin solutions, P (spontaneous igni- tion), aldehyds (most alcoholics contain traces), all tend to darken, especially in the presence of alkalies. Amyl nitrite and aqueous solutions of chloral become acid. Terebene and terpenes become resinous and acid. FeS0 4 becomes coated with a brownish-yellow crust of basic ferric sulphate. Spirit of nitrous ether liberates free nitrous acid quickly in the light. Oleic acid becomes rancid. Mucilage of acacia turns sour and acid on standing, unless some preservative is used. Carbonation. Lead acetate, lime, bleaching powder, KCN,. and bicarbonates generally. Evaporation. Camphor, chloral, menthol, thymol, volatile oils, alcohols, and ethers. Spontaneous combustion usually occurs in compounds con- taining C, 0, and Cl: creasote and Ag 2 0; K 2 Mn 2 8 and glyc- erin or oxalic acid. PRACTICAL EXERCISES ON INCOMPATIBILITIES. (Criticise and correct, if possible, and illustrate in test-tube or cas- serole.) 1. IJ Acidi acet. dil., 3ij ; spt. ammon. arom., 3vj. 2. IJ Argenti nitratis, gr. x; aquae rosae, j$j. 3. IJ Sodii salic., gr. xv; ammonii carb., gr. v; spt. aetheris nitrosi, w?xv; spt. chloroformi, w/x; aquam, ad 3j- 4. IJ Tinct. ferri chloridi, 3ij; quin. sulph., 3j; tinct. cinchonas, 3rj- 5. IJ Hydrogen, diox., 3iv; potassii permang., 3j; glycerin, ad gj. 6. IJ Potassii chloratis, 3j; tinct. ferri chloridi, 3iv; glycerin,, ad 3ij. 7. IJ Potassii iodidi, 3ij; strych. sulph., gr. ss; aquae, 3ij. 8. IJ Liq. potassii arsenitis, 3ij; hydrarg. chloridi corros., gr. j; aquae, 5iv. 9. IJ Hydrarg. bichloridi, gr. xx; sodii boratis, 3ij; aquae, giv. 10. IJ Quin. sulph., 3j; acidi sulph. arom., 3j ; potassii acetat., Siv;. aquam, ad 3iv. 11. IJ Syrupi scillae, 3iv; spt. ammon. arom., 3iv; aquas, 5j. 12. IJ Zinci sulphatis, gr. ij; liquoris calcis, 3j. 13. IJ Liq. potassii arsenitis, 3j; hydrarg. bichloridi, gr. ss; strych. sulph., gr. Y.,; aquam, ad %ij. 14. IJ Plumbi acetatis, 3j; zinci sulphatis, gr. xx; alum, sulph., 3j; aquae, 3j- 15. IJ Acidi chromici, gr. xxx; glycerini, 3iv. 16. IJ Quin. sulph., 3iss; tinct. ferri chloridi, 3iij; ext. glycyrrhizse fl., 3j ; aquam, ad Siv. 20 306 INCOMPATIBILITY. 17. I Spt. camphorse, Sss; spt. chloroformi, 5ss; aquae menthae Pip-, 5j. 18. IJ Infusi gentianae comp., ij ; infusi digitalis, 5j ; infusi cin- chonas, 3j- 19. Ifc Tinct. guaiaci, 3iv; sodii salicylatis, 3ij; aquam menthae " iridis, ad %ij. 20. I Spt. menthae pip., 3ij; tinct. capsici, 3iv; aquam, ad 3j. 21. R Acidi nitrohydrochlorici, 3iv; tinct. cardam. comp., iss. 22. IJ Sodii salic., 3ij ; acidi hydrochlor., 3j ; aquam menthae viridis, ad Sij. 23. I Ammon. carb., 3j; ammon. chloridi, gr. xxx; syrupi scillae, 5j; syrupi ipecac., j; syrupi prun. Virg., Sij- 24. IJ Tinct. ferri chloridi, 3ij; acidi carbolici, 3ss; glycerin, ad j. 25. I Collodii flex., tinct. iodi, aquae ammonise, of each, 3iv. 26. How combine tincture or fluid extract of cannabis Indica with an aqueous solution? 27. Explain the effervescence of spirit of nitrous ether with buchu or uva ursi. 28. Explain effervescence in making Dobell's solution. 29. What objection to magnesia alba as a distributing agent for the preparation of aromatic waters? 30. Under what circumstances will spirit of nitrous ether give a brown color with iodin? 31. What causes the effervescence when glycerin, borax, and fluid extract of licorice are mixed together? 32. If a ppt. ensues on dissolving calcium hypophosphite in distilled water, what adulteration is present? SANITARY CHEMISTRY. THE AIR. AIR is contaminated by respiration, combustion, fermenta- tion, putrefaction, and various trade and manufacturing proc- esses. The C0 2 in the air should not exceed 6 parts in 10,000 when of respiratory origin; at this point vitiation is noticeable to the sense of smell. One pound of coal requires 240 cubic feet of air for complete combustion, and gives off 3 pounds of C0 2 . One cubic foot of coal-gas combines with 5 to 8 cubic feet of air. A common gas-burner consumes about 4 cubic feet of air hourly and furnishes about 2 cubic feet of C0 2 ; 1200 cubic feet of fresh air is sufficient for every cubic foot of gas consumed. The vitiation of air from decomposing organic matter increases pari passu with the amount of C0 2 ; hence the latter is a measure of the former. Experiment. Test the CO 2 of the atmosphere quantitatively with decinormal oxalic acid solution and lime-water: standardize 100 c.c. of latter with former, then take another 100 c.c. of the lime-water, shake in a bottle of known capacity, and titrate again with the decinormal solution. The difference in c.c. between the two titration readings = Ca(HO) 2 pptd. as CaCO 3 . This difference X 0.0037 = weight of the hydrate changed to carbonate; and this product X *Y 7 4 weight of C0 2 causing the change. By comparing the weight found of C0 2 with the weight of the same volume of air (1.29 gm. per liter) the actual propor- tion of the gas is determined. Simply stated, a liter of in-door air should not decolorize (from phenol-phthalein) more than 1.3 c.c. of saturated lime-water after standing several hours. Air containing an excess of C0 2 is detrimental to the health more from the coincident diminution of and the con- comitance of organic matter than on account of the C0 2 per se; as much as 10 per cent, has been borne when simply added to the respired air. A slight excess of C0 2 in sleeping-rooms leads to morning fatigue and drowsiness. Chronic C0 2 poisoning leads to anemia and debility and predisposes to infectious dis- eases, particularly phthisis. CO, is greatly increased in ground- air; is diminished. The proportion of water in in-door air varies greatly with local conditions, both within and without the house. Too little moisture causes a disagreeable dryness of the throat and fauces; too much predisposes to rheumatism and other diseases. One (307) 308 SANITARY CHEMISTRY. pound of fresh lime left in a room for twenty-four hours ought not to increase more than 1 per cent, in weight from absorption of water-vapor. The most important impurities of the atmosphere include NH 3 (from stables, vaults, and animal exhalations); H 2 S, NH 4 - HS, and CS 2 (from decomposition of substances containing S); S0 2 and mineral acids, especially nitrous and nitric (from combustion and electricity); amins, ptomains, and leucomains. H 2 S0 3 in the atmosphere may make the rain acid, with de- structive effect on mortar and soft building-stone. Sore throat and bronchitis are sometimes caused by leaking illuminating gas, soot, or H 2 S0 3 . The organic matter from the skin and lungs consists of epithelia, fatty debris, and volatile fatty acids. These putrefy very quickly, giving rise to the bad smell of close rooms, and are absorbed by water and hygroscopic substances. This or- ganic matter, reckoned as albuminoid ammonia (see "Water"), should not exceed 0.08 mg. per cubic meter. Experiment. Blow through a glass tube into Nessler's solution and show that NH 3 is present in exhaled air. Nessler's reagent is made by dissolving 35 gm. of KI in 100 c.c. of H 2 O, and 17 gm. of HgCl 2 in 300 c.c. of H 2 O; add first solution to second until ppt. at first formed nearly redissolves, and make up to a liter with 20 per cent. NaHO. The solution is improved by keeping; any deposit may be left in and the clear fluid above decanted as needed. It gives a yellow to brown color or ppt. with free ammonia. A known volume of air may be sucked by an aspirator through a specially arranged apparatus containing ammonia-free distilled water, and the liquid then analyzed for free and albuminoid NH 3 , like a water. There is always in poorly ventilated houses a considerable quantity of animal and vegetable debris floating in the air, along with many varieties of germs, some of which are pathogenic. Experiment. Prove organic matter in exhalations by blowing into a very weak solution of K 2 Mn 2 O 8 acidulated with H 2 SO 4 . The solution is decolorized. Aitken has found that condensation of aqueous vapor re- quires the presence of dust in the atmosphere. By means of an ingenious mirror apparatus he has counted the number of particles of dust in a given space at various places and times. He estimates that ordinary still out-door air contains from 1,000,000 to 5,000,000 particles per cubic inch; that of living- rooms, 20,000,000 to 100,000,000. The amount of matter sus- pended in the air is less after a rain or snow-storm and in higher altitudes. The more dust, the more microbes in the air. By the time the air reaches the pulmonary vesicles it is usually sterile. WATER. 309 Most infectious diseases are propagated by the passage of germs through the air; hence the necessity of isolating and confining patients with such disorders. By proper ventilation deleterious substances in the air of rooms are greatly diluted, and the health of the occupants conserved. An adult individual at rest should be supplied with 3000 cubic feet of fresh air per hour: i^ = 0.6 CO 2 per 1000, the limit of health. D ( d r \ E (amount of CO 2 exhaled) _ 0.6 r (respiratory impurity per cubic foot) 0.0002 cubic feet per hour ; BO that the respiratory impurity may not exceed 0.2 per 1000. The vegetable and mineral matters inhaled by persons following certain occupations as millers, bakers, textile work- ers, cutlers, lapidists, miners, quarrymen, stone-cutters, and potters tend to irritate and produce disease of the lungs, espe- cially emphysema, fibroid phthisis, and chronic interstitial pneu- monia and pneumonokoniosis. Poisoning from Pb, Hg, As, or brass may take place through the air. The so-called noxious or offensive trades are those of boil- ers of blood, bones, tripe, or soap; tallow-melters, fellmongers, tanners, gut-scrapers, and glue-makers. Acute mephitic poisoning from open foul drains and cess- pools is characterized by sudden severe vomiting and purging, headache, acute prostration, and sometimes partial asphyxia. The long-continued inhalation of sewer-gas and drain-air pro- duces gradual loss of health, with anemia, lassitude, headache, sore throat, diarrhea, vomiting, and often fever. WATER. Natural waters are more or less pure according to their source and course. For convenience they may be classified as potable (drinkable) and mineral, the latter being unfit for ordi- nary use, but presumably good for sick people. Potable water includes that from rain, snow, ice, lakes, ponds, rivers, springs, wells, and cisterns. The purest natural water is that from snow falling on mountains. The latter part of a rain-fall or snow-fall is purer than the first part, as many impurities are by this time washed out of the air. Among the most common of these contaminations are NaCl, H,S0 4 , HN"0 3 , H 2 S, S0 2 , NH 4 salts, soot, mineral dust, and organic matter. 310 SANITARY CHEMISTRY. Rain-water from roofs and that collected in large cisterns is notoriously unfit to drink, the contained organic matter under- going putrefaction in a few days; the water from cisterns may also contain Pb. The usual source of hydrant-water is from ponds, lakes, and rivers: that is, surface-water. It is very important that no sewage enters the stream above the site whence the supply is drawn. The relative purity of ice-water depends on its source. It is always purer than the water from which it was formed, but may still contain dangerous germs (typhoid, cholera) or their spores capable of originating deadly diseases. The flat taste of ice-water is due to the expulsion of dissolved gases in the process of freezing. Spring-water and well-water are, in reality, nothing else than filtered rain-water containing an excess of C0 2 frequently, and considerable mineral matter which the C0 2 aids to dissolve. The sanitary condition of su.ch waters depends on the depth of the excavation, the character of the soil and underlying strata, and the presence or absence of decaying organic matter in the area of drainage. Shallow wells are little more than cess- pools when placed in the neighborhood of a barn or privy-vault. They drain, it is said, a cone of earth, the base of which has a radius equal to four times the depth of the well. The grossly polluted waters of many shallow wells are, as a rule, clear, sparkling, and palatable; but they quickly become turbid and putrid when kept in a bottle in a warm place. Deep wells are one hundred feet or more in depth, or orig- inate beneath a stratum of rock or impervious clay. These wells are safer than the shallow ones, especially if cased with metal, since the deleterious organic matter at or near the sur- face is pretty well destroyed by the time it filters down to the source of the well. Artesian fountains are best of all wells, because the impervious stratum of clay that covers the water- bed prevents access of decaying matter from the surface. Mineral waters, so called, are characterized by containing an unusual ingredient or an excessive amount of some ordinary constituent. According to the chemic nature of such ingre- dients, these waters are designated as saline (neutral salts), bitter (MgS0 4 ), acid (HC1 and H 2 S0 4 ), alkaline (carbonates and bicarbonates), chalybeate (ferrous sulphate, chlorid, or carbon- ate, held in solution by C0 2 ), silicated (siliceous acid), carbon- ated or effervescent (excess of C0 2 with bicarbonates), alum, borax, and sulphureted (H 2 S or alkaline sulphids) or hepatic. Waters that have a laxative effect are termed aperient. Many WATER. 311 mineral waters belong to more than one class. When the tem- perature of a spring is above 20 C. it is called a thermal spring. Mineral waters are highly vaunted by persons who are in- terested financially. As a matter of fact, these waters have little, if any, more value than water per se. The strongest lithia-waters contain only a fraction of a dose in each gallon. In the case of the more common salts, their action is often neu- tralized and one danger substituted for another by the use of these waters, owing to the physiologic incompatibility of the various ingredients. Their ingestion ad libitum is particularly to be deprecated in organic heart disease. Whatever good effects may accrue from the administration of mineral waters must be ascribed to the influence of sugges- tion, rest, and recreation, change of scene, and the action of water as water. It is far more rational for physicians to pre- scribe distilled water with the exact amount of each ingredient desired. The benefits derived in kidney and systemic diseases from baths at hot springs depend, not on any particular com- ponents of the water, but simply on the diaphoretic action of moist heat. Sea-water contains an average of 3 Y 2 per cent, of min- erals, chiefly NaCl (2 2 / 3 per cent.), MgCl 2 , MgS0 4 , and CaS0 4 . It has a local tonic effect, which reacts on the internal organs; and the same is true of carbonated baths. Water for drinking purposes should conform to the follow- ing conditions: 1. It should be colorless, clear, and limpid. Turbidity may be due to either organic or inorganic impurities. A green col- oration (in small quantities) indicates a high degree of vege- table contamination, and is comparatively harmless. Algae and other micro-organisms may color red or greenish blue. A yel- low or brown color may depend on animal matter or sewage, or less often on vegetable debris or iron. Dark-brown, globular masses usually originate in sewage. 2. It should be odorless. Odors may be brought out more distinctly by heating the water in a flask to a little more than blood-heat. Foul odors usually accompany sewer-gas, algae, and putrefying organic matter. An odor like H 2 S may be caused by the penetration of tree-roots, and is sometimes produced by reduction of sulphates through the agency of putrefactive bac- teria (bacillus sulphydrogenus). 3. It should be of agreeable taste: neither flat, salty, nor sweetish. A decided taste is commonly due to a high charge of mineral matter, especially iron and alkaline carbonates. 4. The most wholesome and desirable temperature is be- 312 SANITARY CHEMISTRY. tween 45 and 60 F. Warm storage water is apt to set up summer diarrhea in infants. 5. The quantity by volume of dissolved gases should be from 25 to 50 c.c. per liter of water. These gases are made up chiefly of (1 per cent, volume), N" (2 per cent, volume), and C0 2 (1 per cent, or more volume). The quantity of dissolved is much diminished by excess of animal and vegetable matter, and this diminution (usually in still waters) is often accom- panied by a bad smell and taste. Boiling water drives off the contained gases, giving rise to an insipid taste. The natural taste can be restored by aerating; for instance, by pouring from one vessel to another. 6. In hardness that is, dissolved inorganic solids good drinking-water should not exceed 40 grains to the gallon, or 2 to 4 parts per thousand. Dyspepsia and diarrhea are caused by too much sulphates (above 7 or 8) or by sewage (some- times choleraic). It has long been held that hard waters are a causative factor in goiter. 7. Water fit for internal use obviously should contain no pathogenic germs, as of typhoid, dysentery, or cholera. This is the most dangerous contamination to which drinking-water is subject. Well-water is more likely to cause enteric fever than is river-water, where saprophytic organisms destroy typhoid germs. Various entozoal diseases may also originate in the drinking-water. PURIFICATION. Various methods have been devised for purifying drinking- water for public and private consumption. The water-supply for cities is best clarified by allowing it to settle for a week or so in storage reservoirs, when it is drawn off on to filter-beds several feet in thickness, and composed mainly of coarse sand and gravel with a layer an inch deep of fine sand at the top. This layer of fine sand is the real filtering agent. It purifies water chiefly by condensation of in its upper surface and the entanglement of bacteria in the superficial gelatinous deposit. It should be removed and washed frequently and thoroughly. Another method in use on a large scale is scouring, or agitation and precipitation of solids, both mineral and organic, by the addition of 1 or 2 grains of alum to the gallon of water, thus forming a flocculent magma which carries down the silt and other suspended impurities as with a net. Lime-water may be used to ppt. excess of carbonates. Magnetic-carbid-of-iron beds are also employed for purification on a large scale; these ANALYSIS OF WATER. 313 beds must be aerated occasionally to keep their oxidizing prop- erties. Still another method is to pass the water through a revolving cylinder containing scrap-iron, and then through a trough, where the ppt. of ferric oxid carries down organic matter with it. In London a living filter is employed for the water of the Thames. A layer of mud containing billions of innocuous saprophytes to the cubic foot is spread over the sand layer of the filter-bed, forming a jelly-like crust. These germs seize on all organic matter in the water, oxidizing and destroying it completely, thus affording the most efficient sanitary filter possible. is commonly spoken of as Nature's great antiseptic, yet in its ordinary molecular form it exerts this effect for the most part through the agency of microbes. The great majority of these are not only harmless, but of immense importance in the economy of Nature, requiring atmospheric not only for their work, but for their very existence. Minute animalcules (in- fusoria, water-fleas) and fish aid in purifying water by feeding on nitrogenous matter in sewage. All sorts of household filtering apparatus are in use. Among these may be mentioned brick partitions in cisterns, nests of asbestos, charcoal filters, and those of spongy iron, and silicated and manganous carbon blocks. The best filters prob- ably for domestic use are made of unglazed porcelain (bisque) or fossil clay (compressed kieselguhr). The pores of these are so minute as not to permit IMC passage of micro-organisms. Filters must be cleansed by immersing in boiling water every day or two, as otherwise the germs in them multiply so rapidly as greatly to increase the dangers of pollution that these utensils are designed to prevent. In case of the slightest doubt as to the purity of any given drinking-water, the only safety lies in boiling it. SANITARY ANALYSIS OF WATER. The examination of drinking-water for practical hygienic purposes is accomplished chiefly by chemic tests: that is, in- directly for bacterial contamination. Bacteriologic methods have not proved of much service, as the disease-germs are gen- erally in so relatively small numbers as often to evade search, while contamination from the air or other sources may invali- date the observations. The micro-organisms commonly found in stale water (algae, cyclops, amoebae, rotiferae) are harmless in themselves except as entozoa. Their presence in large num- 314 SANITARY CHEMISTRY. bers, however, points to an attendant pabulum of decomposing organic matter. Color. The color of water is best estimated by filling a 2-inch glass cylinder (closed at each end with a disk of color- less glass) with the water and holding it before an illuminated white surface, or looking down through the column on a piece of white paper beneath. Reaction. Water is normally faintly acid. The reaction is tested with litmus, phenol-phthalein (bleached by C0 2 ) or lacmoid (blue with alkalies, red with mineral acids or ferric salts, unaffected by C0 2 ). Total Solids. The total residue left on evaporation and drying should not be more than 600 parts per million, or 40 grains to the gallon, though the amount has less significance in artesian water than in river-water. This sediment is ignited at a red heat and weighed again. The loss in weight repre- sents organic and volatile matters; the remainder, mineral hardness. The said loss should never reach to 50 per cent. of the total residue. If on heating the first residue it blackens or fumes or smells like burning horn, we may be certain there is an excess of organic matter present. Hardness. This may also be determined by means of a standard soap solution, prepared by dissolving 10 gm. of Castile- soap shavings in a liter of alcohol (60 per cent.) and water (40 per cent.). Each c.c. of the solution represents 1 mg. of CaC0 3 . The solution is added little by little to 100 c.c. of the water to be tested in a flask, and shaken. The addition is continued until the resulting lather remains appreciable for five minutes, and the degree of hardness readily noted from the number of c.c. used. When water contains less than 50 parts of mineral water in 1,000,000, it is said to be soft; when more than 150, hard. The hardness of rain-water is generally less than 1 / 2 degree ( 1 / 2 grain per gallon). Chlorids. An excess of chlorids (more than 5 parts Cl in 100,000) is generally (except in deep water or rain-water) an indication of the presence of sewage, particularly in localities at some distance from the ocean or salt-water lakes or wells. The amount of these salts (NaCl principally) is estimated by means of a standard solution of AgN0 3 containing 4.8 gm. of the latter to a liter of distilled water: AgNO, _L_ Cl _ 4 8 170 ~ 35.4 4 Each c.c. of the solution is equivalent to 0.001 gm. of Cl, or, ANALYSIS OF WATER. 315 if 100 c.c. of water be utilized for the test, each c.c. of the standard solution stands for 1 part of Cl in 100,000 of water. Estimation of Chlorin. Titrate 100 c.c. of water with standard AgNO 3 solution, using K 2 CrO 4 as an indicator. AgNO 3 combines with the chlorids until they are used up, and then with the chromate, forming the orange-red chromate of silver. The reaction is at an end when the red- dish color becomes permanent. The number of c.c. used of the standard solution corresponds to the parts in 100,000 of Cl. Phosphates. Phosphates, if present, are determined by slightly acidulating 500 c.c. of water with HN0 3 , evaporating to 50 c.c., adding a few drops of dilute Fe 2 Cl 6 and then slight excess of NH 4 OH, filtering and dissolving residue in a little hot dilute HN0 3 ; the solution is evaporated, if need be, to 5 c.c., and to this 2 c.c. of (NH 4 ) 2 Mo0 4 is added, throwing down a yellow ppt. of phosphomolybdate of ammonium. More than 6 parts of phosphates [calculated as Ca 3 (P0 4 ) 2 ] in 10,000,000 of water should be regarded with suspicion. Phosphatic rock dissolved by water is pptd. or removed by micro-organisms. Organic Matter. Waters showing a high 0-consuming power are generally more unwholesome than others with a low affinity for 0. A simple test for the 0-consuming power of animal and vegetable impurities in drinking-water depends on the deoxidizing and decolorizing effect on K 2 Mn 2 8 of organic products. Experiment. To a test-tube nearly filled with water add 2 per cent. of strong H ? S0 4 and then 5 drops of K 2 Mn 2 8 solution, 0.300 mg. to the liter of distilled water. Boil for we minutes, when, if the purple color all disappears, organic matter is in excess of sanitary limits (more than 3 parts in 1,000,000). The odors sometimes produced by heating the water resi- due (burning glue, hair, rancid fats, urine, etc.) should give rise to grave suspicion. Ammonia. The total N should not exceed 0.13 to 0.15 part in 1,000,000. In the natural decomposition of organic substances by the and saprophytes of the ground air NH 3 is one of the first products. NH 4 compounds may also be pro- duced by reduction of nitrates and nitrites in presence of or- ganic matter, especially in deep wells. The reagent employed in testing for NH 3 is called Nessler's solution, and is an alkaline solution of HgI 2 prepared by the reaction between KI and HgCl 2 and NaHO (method of prepa- ration under "Air"). This reagent gives a yellow or brown color with free NH 3 , the depth of coloration varying with the amount of this gas present. 2HgI 2 + NH 3 = NHg 2 I + SHI 316 SANITARY CHEMISTRY. The test is a very delicate one, showing, it is said, 1 part of NH 3 in 100,000,000 of water. Albuminoid ammonia, or that present in combination in undecomposed organic matter, is separated from the other constituents by distilling with K 2 - Mn 2 8 and an alkali. To determine the N" of NH 4 compounds place in a glass retort, connected with a Liebig condenser and receiver, 200 c.c. of distilled water and 10 c.c. of a 25-per-cent. solution of Na 2 C0 3 , and distil until the distillate shows no reaction with Nessler's reagent. Then introduce 500 c.c. of the water under examination and continue distillation at the rate of about 50 c.c. every ten minutes. Add 2 c.c. of Nessler's reagent to each 50 c.c. of the distillate, collected separately, and compare color (fully developed in five minutes) with that of pure water con- taining some standard NH 4 C1 solution (0.382 gm. dissolved in 100 c.c. of ammonia-free water, each c.c. being diluted for use Fig. 46. Cylinder for Nesslerization. with 99 c.c. of pure water 1 c.c. = 0.00001 gm. N"), to which 2 c.c. of the Nessler fluid is added. According as the yellow-brown color of the standard mixt- ure is deeper or lighter than that obtained from the water tested, other comparison liquids are prepared containing less or more NH 4 C1 until the colors agree. Successive distillates of 50 c.c. are tested in the same way until no reaction occurs on nesslerizing. The sum of c.c. of diluted standard NH 4 C1 re- quired in making the color-balances represents the number of hundredths of milligrams of N" in the "free ammonia." A ppt. obtained by this method shows an excess of NH 3 beyond sani- tary safety. If the evolution of NH 4 OH continues and increases up to the fourth or fifth distillate, it is probably due to the decom- position of urea or other nitrogenous substance, in which event this part of the process should cease and the next step (for albuminoid ammonia) be taken. ANALYSIS OF WATER. 317 By "albuminoid ammonia" is understood the N of com- pounds convertible into NH 3 by alkaline potassium perman- ganate (8 gm. of K 2 Mn 2 8 and 200 gm. of KHO dissolved in a liter of distilled water, boiled until one-fourth is evaporated, and then made up to a liter with ammonia-free water). The contents of the retort left from the first step are thrown out, the retort rinsed thoroughly, 200 c.c. of distilled water and 50 c.c. of permanganate solution introduced, and the mixture dis- tilled down to about 100 c.c., nesslerizing the last portion of 50 c.c. to make sure that NH 3 is absent. Then add 500 c.c. of the water under examination and proceed with the distillation and nesslerizing just as for the free NH 3 in the first step. The difference between the free NH 3 of the first process and the total NH 3 of the second is the combined or albuminoid NH 3 present in the water. Ammonia-free water for making these tests is prepared from distilled water, which often reacts with the Nessler fluid, by boiling down to three-fourths with a grain of Na 2 C0 3 to the liter, or by distilling water slightly acidulated with H 2 S0 4 . Great care should be taken to prevent extraneous contamina- tion, by rinsing thoroughly all the apparatus used. Nitrites and Nitrates. The next step in the breaking down in the soil of organic matters into simpler substances is the conversion of NH 3 first into nitrites and then into nitrates. These changes can take place only by the aid of the nitrifying germs, which in the presence of mineral matters transform NH 3 into nitrites and nitrates of Na, K, and other metals at hand: salts which are the source of most of the N of plant- structure. It is evident that nitrites in drinking-water are of less serious import than free NH 3 , and that nitrates have a still less serious significance, showing less recent contamination. Un- objectionable subsoil-water from cretaceous strata may contain a proportion of nitrates inadmissible in the case of river-water. Nitrites are sometimes produced by reduction of nitrates by recent sewage, by metals, cement, or new brick-work. They are sometimes present in rain-water, and in deep well-water from lack of to complete oxidation. The total amount of N in nitrites and nitrates should not exceed 1 part in 1,000,000. Well-waters sometimes contain considerable mineral matter and suspended organic substance with but little or no nitrates, owing to a destructive fermentation. Test for Nitrites. Add 1 c.c. each of naphthylamin-hydrochlorate solution (10 gm. of b. naphthylamin and 10 c.c. concentrated HC1, with H 2 O to make 250 c.c.) and of a saturated aqueous solution of sulphanilic 318 SANITARY CHEMISTRY. acid to 100 c.c. of the water. A pink or red color shows that the water contains nitrites. This color, however, to be of sanitary significance, should appear within a very few minutes, as exposure to the air for a longer time causes a similar change, owing to absorption of nitrites from the atmosphere. Test for Nitrates. Evaporate in a suitable porcelain dish 50 c.c. of water to dryness, finishing the process over the water-bath. Next stir the residue thoroughly with 1 c.c. of phenol-disulphonic acid (made by mixing 3 gm. of phenol with 37 gm. of H 2 SO 4 and heating for six hours in the water-bath) and dilute with about 25 c.c. of water; add NH 4 OH in excess and make up the solution to 50 c.c. If nitrates are present, the yellow ammonium picrate is formed, varying in intensity with the amount present. C 6 H 4 OHS0 3 H + HN0 3 = C 6 H 4 OHN0 2 + H 2 S0 4 The proportion of nitrates can be estimated by comparing a standard KN"0 3 solution (0.722 gm. per liter; 1 c.c. = 0.0001 N), of which 1 c.c. is evaporated in a Pt basin, treated as above and made up to 50 c.c. To draw deductions in slight degrees of pollution the nor- mal standard of Cl, NH 3 , etc., in the natural waters of the dis- trict must be known. The proportion of Cl in uncontaminated waters is fairly constant; when due to sewage it (and nitrates) is likely to undergo marked variations. To distinguish between animal and vegetable water-con- tamination is a difficult matter. If the excess of organic matter is accompanied by excess of total solids, Cl, NH 3 , nitrites, and nitrates (unless these have entered the water directly), the source of pollution is generally animal filth or sewage; when these conditions do not co-exist, the pollution is probably vegetable in origin. Decomposing nitrogenous matter yields NH 3 more rapidly on distilling with alkaline potassium per- manganate than does non-decomposing matter. Water con- taining fermenting vegetable matter is colored yellow by boiling with Na 2 C0 3? and nesslerizing the distillate gives a greenish tinge. POISONOUS METALS. The poisonous metals rarely or occasionally found in drinking-water, include Ba, Cr (dye-works), Zn, As, Cu, Pb (dissolved by soft water or waters containing nitrites, nitrates, or excess of C0 2 ; also by humic, ulmic, and other peaty acids and by free H 2 S0 4 formed by oxidation of iron pyrites). One- tenth grain of Pb to the gallon may produce plumbism. Mn, Fe (more than 3 or 4 parts in 1,000,000), and Al are also objec- tionable in notable quantities. Ba is determined by slightly acidulating with HC1 and ADULTERANTS AND SOPHISTICANTS. 319 adding solution of CaS0 4 . Cr is found by evaporating a liter of the water to dryness with a little KN0 3 and KC10 3 and then fusing; any Cr is present in the residue as chromate, and on taking up with acid water gives a blue color with H 2 2 . Zn is best detected by adding sufficient NH 4 OH to render slightly alkaline, heating to boiling, filtering, and treating fil- trate with a few drops of K 4 FeCy 6 . Beinsch's test is best for As, evaporating a liter of the water (rendered slightly alkaline with Na 2 C0 3 ) nearly to dryness and acidulating with strong HC1. KSCN gives a blood-red color with ferric salts, or with ferrous after boiling with a few drops of HN0 3 . H 2 2 gives a brown ppt. with a concentrated water containing Mn. Pb is found easily by adding to the water in a tall glass cylinder a drop of NH 4 HS, giving a brownish-black ppt. of PbS, not cleared up by HC1 (distinction from Fe) nor by KCN (dis- tinction from Cu). The presence of the latter metal may be confirmed by adding K 4 FeCy 6 , getting a mahogany-red color. Water should not be drunk if it contains above 1 / 20 gr. Pb or Cu, V 4 gr. Zn, V 2 gr. Fe per gallon, or the faintest trace of As. ADULTERANTS AND SOPHISTICANTS. FOOD. The pernicious practice of food adulteration is carried on in this country to an extent not tolerated by any other civil- ized nation. While many of the additions are comparatively harmless (sophistication),, th^ T all constitute a fraud upon the purchaser and consumer. Milk. Antiseptic agents are commonly added to milk to make it keep longer. The ones most frequently employed are borax, boric acid, salicylates, and especially formalin (freezine). The main objection to the use of these compounds is the stale- ness of the food which they are used to preserve. Borax and sodium or calcium carbonate increase the total solids of the milk. Condensed milk is skimmed milk boiled down to about a third and fortified with cane-sugar. "Evaporated cream" is made from whole milk similarly condensed. Test for Formalin. Add a few drops of dilute phenol to the milk, and pour the mixture on strong H 2 SO 4 , getting a bright-red ring. Test for Salicylic Acid. Render 25 to 50 c.c. of sample feebly acid with H 2 S0 4 and shake thoroughly with an equal volume of a mixture of equal parts of ether and petroleum spirit. Allow to separate in a funnel and draw off the solvent, filter, and evaporate gently. The needle-like crystals of salicylic acid dissolved in a little water give a violet color with 320 SANITARY CHEMISTRY. Test for Borax and Boric Acid. A few drops of the sample mixed with a drop of HC1 and a drop of strong alcoholic solution of turmeric are evaporated to dryness and a drop of NH 4 OH added to the residue,, giving a dull-green stain. Boric acid is normally present in wine. Skimming milk increases the sp. gr. and diminishes the cream. Milk which has been both skimmed and watered may have a normal sp. gr., but is thin and blue. The bacteria (lactic acid bacillus and others) in badly kept milk may amount to 3,000,000 or 4,000,000 per c.c., and are the active cause of the summer complaint of infants. Milk is also very liable to bear the germs of enteric and scarlet fevers, diphtheria, tuber- culosis, and foot-and-mouth disease; also the mold of thrush (O'idium alhicans). The best preventives of milk-infection are cleanliness in milking and in the care of cows, and keeping the milk on ice from the time it is drawn until ready to be used. Bacteria may be filtered out to a considerable degree through cotton. Butter. The substitution of oleomargarin for butter is readily detected by the marked difference in volatile fatty acids: nearly 8 per cent, in the case of butter and only about 1 / 2 per cent, in oleomargarin. A mixture of butter, oleomar- garin, and cocoa-nut oil may have the same proportions of insoluble acids as butter, and is distinguished by the oleore- fractometer. The sp. gr. of butter is rarely below 0.91; of beef- fat, -never above 0.9045. The m.p. of butter is from 86 to 94 F.; of beef-fat, rarely above 82 P. Test for Butter (Leffmann). Wash a 300 c.c. flask thoroughly; rinse with alcohol, then ether; dry by heating in water-oven, cool, and weigh. Introduce 5.75 c.c. of the sample tested by means of a pipet heated to about 60, and after fifteen minutes weigh again. Then add 20 c.c. of glycerol-soda solution (1 part of 100-per-cent. NaHO solution with 9 parts of pure glycerin) and heat over the Bunsen flame until com- plete saponification takes place (in about fifteen minutes). Dissolve the soap in 135 c.c. of water, gradually added with shaking, and add 5 c.c. of 20-per-cent., by volume, H 2 S0 4 ; drop in a piece of pumice, and distil until 110 c.c. have been collected. If the distillate is not clear, it should be thoroughly mixed and filtered, and 100 c.c. of the filtrate taken. Standardize with decinormal alkali in the usual way; if only 100 c.c. of distillate are taken, the findings should be increased by 1 / 10 . A blank experiment should be made to determine the amount of standard alkali required for the materials (seldom above 0.5 c.c. for good glycerol)* Five gm. of butter yields a distillate requiring from 24 to 34 c.c. of deci- normal alkali to neutralize; commercial oleomargarin (usually churned with milk), 1 to 2 c.c. of the alkali. Butter-fat is readily and completely soluble in ether; beef-fat leaves a residue. Lard is much adulterated with cotton-seed oil or beef- stearin and excess of water. "Compound lard" may be made ADULTERANTS AND SOPHISTICANTS. 321 of maize-, sesame-, and pea-nut oils. "Butterine" has lard added to the milk and oleomargarin-oil before churning. Cheese. Cheese is "improved" in weight by lard, oleo- margarin, cotton-seed oil, and skim-milk. ZnS0 4 ("cheese- spice") is sometimes used to prevent heading and cracking. Cheese is colored with carrot-juice, saffron, yellow ochre, and ferruginous earths; it is flavored with sage and parsley. An- natto, turmeric, and yellow azo dyes are employed to give a rich-yellow color to milk, butter, and cheese. Test for Annatto. Coagulate 1 ounce of milk with a few drops of HC,H 3 O 2 , heat, strain, press out excess of liquid; triturate curd in a mortar with ether; decant ether and add to it 10 c.c. of a 1-per-cent. solution of NaHO, shake and allow to separate; pour off upper layer into a porcelain dish, put in a small strip of filter-paper, and evaporate gently. The strip is colored bulf or orange, turning pink with SnCl 2 . Meats. Sausage-meats are often colored with carmin, fuchsin, eosin, or benzopurpurin. Meats are preserved ("em- balmed") and improved in appearance by the addition of KN0 3 , NaCl, sulphites, salicylic or boric acid, and a little coloring matter. Beginning putrefaction may be detected by holding a rod dipped in a mixture of 1 c.c. each of ether and HC1 and 3 c.c. of alcohol, over the suspected matter, producing fumes of NH 4 C1. Canned Goods. Tinned meats are often preserved by the aid of NaCl, KN0 3 , and boric or salicylic acid. Tinned goods, especially if acid, are likely to become contaminated with the tin of the can or the lead of the solder. Decayed meats act as irritant poisons, giving rise y) vomiting, purging, depression, and frequently a scarlatiniform erythema. Fermented canned vegetables swell out the ends of the container, giving a hollow sound on striking. Bread and Cake. The loss of weight in flour on heating over the water-bath should not exceed 15 per cent.; nor the ashes 2 per cent. Sophistication with potatoes shows increase of water and an alkaline ash. The amount of water in bread should not generally exceed 40 per cent, (up to 50 per cent, when quite fresh). Alum is normally present in flour and bread to the extent of 6 to 10 grains in a 4-pound loaf. The addition of alum makes the loaf whiter and more hygroscopic. Its pres- ence in any quantity may be detected by pouring a fresh in- fusion of logwood (made with distilled water) over the flour or bread. The color of the logwood is changed to lavender or violet-gray. CuS0 4 is sometimes used to make a stale or damaged sam- ple of flour look white; a brown color is imparted to a thin 322 SANITARY CHEMISTRY. slice of such bread when dipped in a dilute solution of K 4 - FeCy 6 . Bread is also adulterated with chalk, gypsum, pipe-clay, ZnS0 4 , magnesia, bone-dust or bone-ash, ammonia, and plaster of Paris. These separate by sinking when flour is shaken with chloroform. The gravest contamination of flour is ergot. This may be detected by shaking 2 gm. of flour with 10 c.c. of 70- per-cent. alcohol containing 5 per cent, of HC1 and allowing to subside; if ergot is present, the supernatant liquid is colored blood-red. Liquor potassae gives a distinct herring-like odor (propylamin) if ergot is present. SnCl 2 and K 2 C0 3 are sometimes used surreptitiously to give to ginger-bread the color imparted by honey or molasses. PbCr0 4 is occasionally resorted to for coloring cakes yellow, but, as a rule, harmless vegetable colors are used for this pur- pose. Baking-powders are commonly adulterated with alum, ammonia, sulphuric acid, and ground rock. Sugar and Molasses. Glucose is used largely in cheap syrups, strained honey, and to dilute brown or maple sugar. It is best determined by the polarimeter, and often contains As from impure acids used in its manufacture. Much "mapleine" is made by adding extract of hickory-bark to sucrose or glucose syrup. Dark molasses is sometimes bleached by Zn dust and Na 2 S0 3 , Zn being subsequently removed by oxalic acid. SnCl 2 is sometimes used to give a bright-yellow appearance to syrups. Granulated and loaf sugars often contain ultramarine blue to improve the color; it is decomposed by HC1, showing the blue color. Jellies and jams are often nothing else but glucose and starch paste, flavored with essential oils. If honey gives a ppt. when treated with excess of alcohol, the dextrin of commercial glucose is present. Test for Saccharin (TJsed as a Preservative). Extract 50 c.c. of sample, acidulated with 25-per-cent. H 2 SO 4 , with a mixture of equal parts of ether and petroleum spirit, and evaporate solvent at a gentle heat. The sweet residue is heated with 2 c.c. of saturated NaHO solution until mass fuses for one-half hour, when saccharin is changed to salicylic acid. If the latter was originally present, it may be separated by dissolving the ether residue in 50 c.c. dilute HC1, adding Br water in excess, shaking well, and filtering off the brominated salicylic acid. Vinegar. Pure vinegar (wine, cider, spirit, malt) should contain between 5 and 6 per cent, of acetic acid and have a sp. gr. of 1.008 to 1.018. Mineral acids are detected by adding a solution of methyl violet, which turns blue with mineral, but not with organic, acids. H 2 S0 4 is also detected by evaporating some of the vinegar with a little cane-sugar nearly to dryness, getting a black color, due to charring. Fruit-stand "cider" ADULTERANTS AND SOPHISTICANTS. 323 usually consists of a weak solution of cider-vinegar flavored with rose-water and sparingly sweetened. Pickles are generally brightened in color with chlorophyl or other vegetable colors, but CuS0 4 is occasionally used. This may be easily detected by immersing a knife-blade or other strip of metal in the liquid, getting a red coating of Cu. Confectionery. Sweetmeats are colored by careful heat- ing (yellow and brown) or by saffron, turmeric, annatto, cochi- neal, logwood, and chlorophyl. A very weak solution of eosin is used to color red, fluorescein and auramin for yellow, and malachite for green. Other colors less often employed are fuchsin, Bismarck brown, and ferric hydroxid (for chocolates), verdigris, chrome-yellow, picric acid, and gamboge. Organic compounds are distinguished by being soluble in alcohol and bleached by NaClO. To detect mineral adulteration (chalk, plaster of Paris, sand, clay) incinerate and dissolve the ash in dilute HNO 3 and employ the ordinary group tests. Fuchsin may be found by shaking the neutral solution with a mixture of equal parts of ether and amylic alcohol, which are colored red or pink on separating. Potato-meal is sometimes added to candies. Coffee. Roasted coffee floats for some time on water, while roasted chicory quickly sinks. Chicory contains considerable sugar, and hence gives a darker infusion than pure coffee. Ground coffee is further sophisticated with cocoa-shells and roasted vegetables and cereals; also, it is said, with roasted horse-liver flavored with caramel. Imitation coffee-beans are made by special machineryirom roasted acorns, burnt sugar, chicory, and roast horse-liver. Chicory is revealed microscopic- ally by the long dotted ducts in its structure. It is itself adulterated with colored earths, oak-bark, and sawdust. Tea. This is greatly adulterated with the leaves of various trees faced with plumbago, Cu, Fe, and with catechu, added for its astringent effect. Tea-leaves are sometimes colored black with plumbago; green with CuS0 4 and Prussian blue. Used leaves are often dried, rolled, and resold. Lie tea is an imitation made of dust and tea-sweepings, along with minerals held together by means of starch or gum; it is broken down by boiling water. Cocoa. This is generally adulterated with sugar and the cheaper starches to cover the excess of fat and render more palatable. Chocolate is often adulterated with ground pea- nuts and almond-meal. Wines. Cheap wines are made largely from other fruits than the grape, especially raisins. Champagne has been made 324 SANITARY CHEMISTRY. entirely from gooseberries and water. Sulphurous acid is often present in wines., from sulphites used as preservatives or from the burning of S to disinfect the casks. Pb is sometimes found in white wines, where it has been placed to sweeten the product. Red wines are sometimes decolorized to white by means of charcoal. Sulphate of lime is sometimes used to improve the color of cheap wines ("plastering"), and logwood, alum, sugar, and added ethers are common adulterants. Beer. The bitter taste of beer, normally due to hops, is often produced by picric acid, strychnin, or picrotoxin. Test for Picric Acid. Evaporate Y 2 to 1 liter of beer to dryness on water-bath; treat with alcohol, filter, and evaporate filtrate; dissolve residue in boiling water and evaporate again; extract residue with ether, which dissolves the acid and on evaporation leaves it as yellow needles giving a blood-red color with KCN (isopurpuric acid). Basic lead acetate and a little ammonia ppt. all the bitter substance of hops, but not of strychnin or picrotoxin. Added glycerin is detected by the acrid vapors on incinerating a residue of beer after evaporation. Other common adulterants are alum, H 2 S0 4 , cream of tartar, potash, calamus, caraway, coriander, copperas, capsicum, ginger, quassia, wormwood, and ground oyster-shells. Spirits. Young raw whisky contains fusel-oil (later changed to ethers), the odor of which is best detected by evaporating slowly on the water-bath. Hanson says that fusel- oil with other adulterants will make a very fair whisky for 5 cents a gallon. Acids are often added to imitate the acid reaction of mellow age (due to acetic and a trace of valeric). Added ethers may be detected by Molnar's test, which consists in evaporating a little whisky with excess of KHO; on adding excess of H 2 S0 4 to the residue the volatile acids, with charac- teristic odors, are liberated. So-called gin is often made from a mixture of sugar, water, cinnamon, alum, cream of tartar, capsicum, and a little alcohol. Condiments. Ground spices are very commonly adulter- ated with cocoa-shells, bran, rolled oats, pease, cornmeal, buck- wheat, starch, sawdust, flour, etc. Tobacco. Among the adulterants of tobacco we find hay, apple-parings, corn-husks, paper, cabbage, potato-leaves, rhu- barb-leaves, endive, elm, beet-root, dock, sea-weed, sawdust, copperas, and coal-dust. ADULTERANTS AND SOPHISTICANTS. 325 DRUG IMPURITIES. Arsenic is frequently present in bismuth salts. Most mer- curous salts contain traces of the corresponding mercuric salts. FeS 2 is often found in reduced iron; H 2 S is evolved on treating with acids. Bromates in alkaline bromids liberate free Br on adding dilute H 2 S0 4 . lodates in iodids liberate free I in con- tact with mineral acids. Bi in Hg is readily detected by shak- ing Hg in a test-tube, when the Bi separates as a black powder. Common salt commonly contains some MgCl 2 . Hypophosphites often contain an excess of sulphates. Cream of tartar is often adulterated with starch, alum, and acid calcium phosphate; less often with calcium sulphate and potassium acid sulphate. The best baking-powders should yield about 12 per cent., by weight, of gas, but many yield much less. Compound spirit of ether contains a little free H 2 S0 3 . Gums are notoriously impure, often containing dirt, sticks, bark, and pebbles. Digitalis is often substituted by mullein- leaves and elecampane-leaves; saffron with calendula; senna with argels. Spanish saffron is increased in weight by coating the stigmas with colored CaC0 3 . "Venice turpentine" usually consists of a mixture of resins with oil of turpentine; "Bur- gundy pitch," of melted resin and fat, with sufficient water to render turbid. Balsam copaibas is commonly adulterated with East-India wood-oil and paraffin- or vaselin- oil. Essential oils are very commonly sophisticated: oil of rose with Indian grass-oil. Olive-oil is generally adulterated with oil of cotton- seed, walnut, sesame, poppy, rape, or pea-nut; codliver-oil with porpoise, shark-liver, and other cheap fish-oils. When shaken in a test-tube with an equal volume of nitric acid pure olive- oil should show a green coloration; cotton-seed, a red color. Cacao-butter is adulterated with tallow, lard, stearic acid, paraffin, bees-wax, and cocoa-nut and arachis oils. Imitation bees-wax is sometimes made from tallow hardened with sper- maceti and carefully colored. All crude drugs (especially cinchona and cannabis Indica) vary greatly in the content of active principles. A purple color is produced on heating powdered cinchona in a test-tube if sufficient alkaloids are present. In the United States Pharma- copeia will be found many practical tests for chemic impuri- ties, both qualitative and quantitative, the latter being chiefly volumetric for the permissible limit of impurities. 326 SANITARY CHEMISTRY. ANTISEPTICS AND DISINFECTANTS. A disinfectant or germicide is "an agent capable of de- stroying the infective power of infectious material": that is, specific germs. An antiseptic retards or arrests bacterial growth and toxin formation; it may or may not be germicidal. A deodorant is an agent that absorbs or oxidizes offensive odors; it is rarely germicidal. The removal of any and every kind of dirt and filth is essential to the proper office of these agents. Since perfect asepsis is impossible, antisepsis must often be added to cleanli- ness. Disinfection, in general, depends upon (1) heat, (2) oxidation, (3) sunlight or actinism, (4) reduction, (5) coagula- tion, and (6) direct toxic action upon bacteria. Of all disinfectants, the most efficient is moist heat, to which, at the temperature of boiling water, all pathogenic bac- teria and their spores succumb within five minutes. For ster- ilizing .instruments for an operation nothing is better than boiling them for at least five minutes in pure water, to which 1 per cent, of ]STa 2 C0 3 may be added to cleanse adherent grease and prevent rusting. Gauze and other dressings should be sterilized by steam heat just previous to being used. Dry heat is not nearly so effective as moist heat, and when necessary to resort to this method it should be applied at about 300 F. and fractionally, that is, for a short time on successive days, in order to destroy any spores that may have resisted the heat and developed into germs. Acetanilid. This remedy in powdered form is used by many physicians as a local antiseptic, particularly in the treat- ment of chancroids. Like other coal-tar preparations, it may give rise to depression and cyanosis. Acetylene. This gas, freshly generated by applying CaC 2 to moist surfaces, has been used as a deodorant in cancer of the womb and similar conditions. Alcohol. The antiseptic properties of alcohol depend on its dehydrating and coagulating effects, by which the germs are deprived of the moisture necessary to their growth and are also acted upon directly as to their waxy capsules. It is some- times used as an intra-uterine injection in cases of puerperal fever. Benzole Acid. This acid is not to be classed as a ger- micide, but has sufficient inhibitory activity (1 to 900) to pre- vent the rancid decomposition of animal fats, and hence is much used in ointments. Internally in doses of 10 to 30 grains ANTISEPTICS AND DISINFECTANTS. 37 benzole acid is a serviceable antiseptic remedy in chronic cys- titis. Boric Acid. It is inhibitory rather than germicidal. A 1 to 133 solution arrests the activity of most bacteria. It is free from irritating or toxic qualities and from disagreeable taste or odor. A saturated solution (4 per cent.) is commonly employed for the sterilization of mucous surfaces, and is a good deodorizer in cases of fetid perspiration. A 1-per-cent. lotion is used extensively for preventive purposes in cleansing the mouth, nose, and eyes of infants as well as the nipples of the mother. Boric acid is frequently added to alkaloidal solutions, to forestall decomposition. Insufflations of the dry powder into the auditory canal after cleansing the latter are generally rapidly curative in suppuration of the middle ear. Borax is also slightly antiseptic, and in saturated solution (12 per cent.) has yielded good results in the various forms of tinea. The glycerite of boroglycerin is made some use of as an antiseptic vehicle for alkaloids and glucosids in the local treatment of skin and eye diseases. Bromin. Like the other members of the halogen group, this element is a disinfectant and deodorizer of great power. Over 6000 pounds of Br were used at Johnstown, Pa., after the great flood in 1889. The highly corrosive nature of the liquid and the irritating character of the fumes which it evolves make its employment out of the question in the operating-room and in the sick-chamber. The bromids are also antiseptic, NaBr in 10-per-cent. solution being destructive to the germs of cholera and typhoid. Carbolic Acid. The disinfectant properties of phenol were first recognized by Chaumette in 1815, but it was not until 1867 that the new era of surgery was inaugurated by Lister in his memorable communication on the merits of this drug. The disinfectant potency of phenol is well established. Generally speaking, we may be certain of reliable antiseptic results with a 5-per-cent. solution of the acid. In this strength it is much employed to sterilize instruments, particularly those that would be injured by heat. According to Yersin, a 1-per-cent. solution will destroy tubercular bacilli in one minute. Carbolates and sulphocarbolates are much weaker. Carbolic acid coagulates albumin with facility. It can act in the presence of sebaceous and oily matters. It is an effective local anesthetic, and is sufficiently soluble in the common solv- ents. The chief objection to carbolic acid is liability to sys- temic poisoning, manifested by smoky urine, pain in the lumbar region, dyspnea, and possibly collapse. It also benumbs and 328 SANITARY CHEMISTRY. corrodes the hands and dulls the instruments of the operator. The former use of the carbolic spray during operations rested on the faulty supposition that infection took place through the atmosphere rather than by way of the hands, dressings, and instruments. The attempts at disinfection of a sick-room with vapors of carbolic acid or similar compounds are equally illog- ical and futile. Chloral Hydrate. A 5-per-cent. lotion has been used with satisfaction in the treatment of foul ulcers and parasitic skin affections. It is also employed as a deodorant in the urinals of paralytic patients. Chlorin. The disinfectant value of this element has been recognized since its discovery by Scheele in 1774. It has a great affinity for H, which it takes from H 2 0, setting free the powerful germicide nascent 0. Hence the necessity for moist- ure in the use of this agent. Cl also acts as a deodorizer by taking away the H of sewer-gas. Nissen determined that a solution of 1 / 2 - to 1-per-cent. strength destroys the germs of typhoid and of cholera within five minutes. Cl for disinfecting purposes is derived almost exclusively from calx chlorata, the so-called chlorid of lime, which evolves the gas gradually in the presence of moisture. It should con- tain at least 25 per cent, of available Cl. Chlorinated lime is altogether the most suitable substance for deodorizing drains, sinks, and water-closets, and for disinfecting alvine evacuations and other discharges. For the latter purpose the fresh powder should be used in the proportion of a half-pound to the gallon. It ought always to be placed in the vessel before depositing the excretions therein. Common salt and ZnCl 2 are inimical to all low forms of life. Of the former, a saturated solution, says Miquel, will kill cholera spirilla in a few minutes. The latter compound is anti- septic in the strength of 1 to 25. A 10-per-cent. lotion is a serviceable caustic application for foul ulcers. Chloroform. This well-known anesthetic prevents fer- mentation due to micro-organisms, while it does not impede the function of the unorganized digestive ferments. Water and spirit of chloroform are therefore efficacious remedies in digestive disorders attended with fermentation and flatulence. Chromic Trioxid. Koch asserts that Cr0 3 is markedly germicidal, and Miquel claims that it is antiseptic in a 1 to 5000 solution. The drug is, however, very irritating and caustic, and death has ensued from its too free application. Citric Acid. A solution 1 to 200 in strength will kill the spirilla of cholera on a half-hour's exposure; hence the benefits ANTISEPTICS AND DISINFECTANTS. 399 from drinking lemonade in times of cholera and other water- borne infections. Copper Sulphate. In 5-per-cent. solutions this salt is a powerful disinfectant (coagulates albumin) and an absorbent of H 2 S and ammonias. Creasote. Beech-wood creasote, in spite of its irritating properties, is still widely employed as an intestinal antifer- mentative and digestive stimulant, particularly in tuberculous cases. Creasote is related to phenol, and is apt, when used in excess, to produce analogous symptoms of systemic poisoning, such as headache, stupor, and smoky urine. Schill and Fisher found that a 1-per-cent. solution of creasote failed in twenty- four hours to kill the tubercle bacillus. Creolin. A 2- to 5-per-cent. emulsion with water is some- times used for vaginal injections, and stronger mixtures are employed for general disinfection. Lysol is a similar mixture of cresols, and is freely soluble in water. Cyanid of Zinc and Mercury. This insoluble compound has been used to some extent in the form of gauze for surgical dressings. It is feebly germicidal, strongly antiseptic, and non- irritating, but extremely poisonous, on which account its use should be condemned. Ether. Ethylic ether in full strength is an efficient ger- micide. Its chief use in surgery, however, aside from anesthe- sia, is to dissolve and remove the fatty matters of the skin before applying antiseptic solutions. It is employed for the same purpose in the preparation of surgeon's catgut. Eucalyptol. This is a camphor-like substance credited by Behring with an antiseptic potency one-fourth that of carbolic acid. The eucalyptus preparations are indicated in chronic urinary diseases associated with decomposition of urine within the body. Ferrous Sulphate. Copperas is not a germicide, but has weak antiseptic properties and in strong solutions is of service as a deodorizer for vaults and other damp places. Formaldehyd. The marked efficiency of this gas was dis- covered by Trillat and Aronson in 1892. A 1-per-cent. solution destroys nearly all germs in less than thirty minutes. The gas is an admirable surface disinfectant, but has not the penetrating power of S0 2 . Its germicidal power is probably due to the fact that it renders albuminoids insoluble in water. For disinfecting rooms the gas may be produced by heat- ing solid paraformaldehyd over an alcohol-lamp; or it can be developed directly by oxidation of methyl alcohol, the vapors of which are made to pass through heated metal tubes or coils. 330 SANITARY CHEMISTRY. Another method, recommended by Novy, is to heat formalin (40-per-cent. aqueous solution) containing 10 per cent, of glyc- erin or a little CaCl 2 (dehydrates gas); or by dipping sheets in a weak formalin solution and hanging them upon lines in the room. As HCOH is quite diffusible, all apertures of the room should be kept tightly closed for six or eight hours while the gas is operating. Its irritating odor is quickly dispelled by evaporating some NH 4 OH in the room. For thorough disin- fection it is well also to wash the furniture with antiseptic solutions, to rub the wall with bread-crumbs, to scrub the floor thoroughly, and to boil all the clothes and bedding that can be treated in this way. For surgical use formaldehyd is utilized in 1 / 4 - to 1 / 2 -per- cent. solutions; for general antisepsis, Y 2 - to 2-per-cent. solu- tions; and for sterilizing catgut, a 4-per-cent. solution. Like HgCl 2 , formalin roughens and hardens the hands. Paraform pastils are very convenient for sterilizing catheters by keeping them together in a closed box. Glycerin. Copeman discovered in 1891 that glycerin is able to sterilize vaccine pulp sufficiently for clinical purposes, without affecting the properties of the unknown vaccinia germ, and glycerinated lymph, preserved in sterile capillary tubes, is at present the most convenient and acceptable form of vaccine. lodoform. The clinic benefits accruing from the applica- tion of CHI 3 depend mainly on starving the germs by absorp- tion of local secretions and on chemic changes in the toxins. In the presence of much moisture free I is also evolved, and aids in the approximate sterilization of the tissues. Some micro-organisms grow in iodoform, and prudence dictates that the drug should be itself sterilized by heat before using it. A 10-per-cent. solution in olive-oil is especially valuable for in- jection in tubercular affections of the joints. The immoderate use of iodoform as an application to fresh wounds is a matter to be deprecated, since alarming toxic symp- toms may follow: such as erythema or eczema; headache; faint- ness; prostration; high fever; rapid, feeble pulse; amblyopia; and cerebral phases simulating meningitis. Elderly persons are especially susceptible to the deleterious influence of the drug. The invincible odor of CHI 3 is very offensive to sensitive patients. Of the many iodoform substitutes, iodol is probably best. Lactic Acid. Although the product of alimentary fer- mentation, this acid, in larger quantity, inhibits fermentative changes. Kitasato states that a 4 to 1000 solution is destruc- tive to typhoid bacilli. ANTISEPTICS AND DISINFECTANTS. 331 Lime. Fresh CaO is a strong germicide, 1 to 1000 being sufficient to destroy cholera and typhoid germs. It is used mainly for disinfecting manure-heaps and privy-ordure. Mercuric Chlorid. The reign of corrosive sublimate as an antiseptic began in 1881, when Koch affirmed its generally germicidal action in solutions as weak as 1 to 15,000. A 1 to 1000 solution is needed for non-spore-bearing bacteria; 1 to 500 for the spore-bearers. Abbott has ascertained that a 1 to 500 solution will not destroy pus-cocci even in the absence of spores. It has been demonstrated by a number of observers that the action of strong solutions of HgCl 2 is not germicidal, but inhibitory, and that when the chemical is pptd. from the germs they again resume their vital functions. The principal objections to the use of HgCl 2 as an anti- septic are as follows: It is irritating to the tissues, even causing necrosis. Strong solutions roughen the hands. If absorbed to the extent of a grain or more, it is apt to produce alarming toxic symptoms. It combines with albumin, forming an in- soluble and inert (while undissolved) compound; nor can it act in the presence of fat or soap. In aqueous solution it is quite unstable, tending to reduction into calomel. It is very corrosive to instruments. Despite the above disadvantages, HgCl 2 remains the favorite antiseptic of a large proportion of physicians and surgeons. That such should be the case shows merely that a dictum, once established, is difficult to overthrow. Methylene Blue. This is a valuable urinary antiseptic when given by the mouth. It colors the urine blue or green. The conjoint administration of spices prevents gastric irrita- tion. Mineral Acids. Hydrochloric, nitric, and sulphuric acids have each slight antiseptic energy. The first named has sup- planted lactic acid in the treatment of ordinary stomachic in- digestion. Mustard. A solution of the oil of black mustard only 1 to 33,000 is capable of preventing the development of an- thrax-spores. All the essential oils have more or less antiseptic power. Naphtalin. Naphthalene is utilized as a prophylactic against moths. Betanaphtol is sometimes administered^ as an intestinal antiseptic. It is liable to be contaminated with its poisonous isomer, alphanaphtol. The derivative hydronaphtol is also prescribed as an intestinal disinfectant. Oxygen. Despite the popular belief to the contrary, ordi- nary molecular is not directly germicidal except in the case of the relatively rare anaerobic bacteria. It is the freshly lib- 332 SANITARY CHEMISTRY. erated or nascent atomic form of the gas which is a true and powerful germicide. Whatever merits ozone may possess as a disinfectant are due to breaking up of the gas into nascent and the ordinary form. The good effects derived from the use of wood-charcoal in fermentative disorders depend largely, no doubt, on the occluded in its pores, as well as on absorption of the abnormal gaseous products. Peroxid of Hydrogen. This is likewise an oxidizant, lib- erating free (ordinarily about 10 volumes) in the presence of all kinds of organic matter. It seems to have a special affinity for pus, and may be used to detect the presence of a purulent secretion in a cavity, by the effervescence which en- sues on injecting the fluid. The principal objection to the remedy is its instability and the consequent uncertainty of each specimen. Other disadvantages are its corrosive action upon metals and the danger of explosion of the confined fluid when heated. Petroleum. Crude petroleum and kerosene have come into extensive use of late for destroying the larvae of yellow-fever- and malaria- bearing mosquitoes. The oil is spread on the sur- face of pools infested by these insects. Potassium Permanganate. This is an efficient oxidizing germicide. The tubercle bacillus is the only common pathog- enic germ which withstands the action of a 5-per-cent. solu- tion. The drug is not adapted to internal administration, since it is quite irritating to the stomach; in the presence of readily combustible substances it has sometimes exploded. According to Weir Mitchell, it is the most efficacious local antidote for snake-bite. K 2 Mn 2 O s has of late years risen to prominence as a dis- infectant for the surgeon's hands. The method, introduced by Kelly, consists of three steps: first, scrubbing the arms, hands, and nails thoroughly with soap and hot water; second, immer- sion of the parts in a saturated solution of permanganate; third, washing off the K salt with a saturated aqueous solution of oxalic acid until the purple color has all been removed. Oxalic acid itself is a strong antiseptic, and so reinforces the action of the permanganate. The resulting itching of the skin, if annoying, may be relieved by bathing with sterilized lime- water, also an antiseptic. Quinin. The salts of quinin have a special destructive predilection for the Plasmodium malarice, even in as weak solu- tion as 1 to 20,000. The sulphate is generally antiseptic in the strength of 1 to 800; the hydrochlorate, 1 to 900. ANTISEPTICS AND DISINFECTANTS. 333 Resorcin. This benzene derivative has come into promi- nence as a gastro-intestinal antiseptic and as an ingredient of soaps and ointments for parasitic and scaly skin diseases. Large doses, Y 2 dram or more, induce the symptoms of de- pression characteristic of phenol compounds. Salicylic Acid. According to Miquel, this product is anti- septic in the strength of 1 to 1000. Its unquestioned efficacy in rheumatism probably depends on its antiseptic properties. It is not a good dressing for wounds, since it irritates and macerates the tissues and does not stay in place. The internal administration of the acid made from phenol, particularly, may cause roaring in the ears, headache, delirium, and erythema; 48 grains taken within four hours have produced death in an adult. Salol. The salicylate of phenol is broken up by the pan- creatic juice into carbolic and salicylic acids. It has been used extensively for infectious intestinal diseases and even for chol- era, but Eeiche states that in the Hamburg epidemic of 1892 salol was an utter failure. Salophen and aspirin seem to possess all the advantages of salol and ealicylates without any of their objectionable features. Silver Nitrate. This well-known compound has been rated by Behring next to HgCl 2 in antiseptic potency. It can be utilized in nearly all inflammatory and ulcerative states of the mucous membrane. Perhaps its most noteworthy applica- tion is in ophthalmia neonatorum. The use of AgN0 3 as an antiseptic is limited by the discoloration of the tissues which it produces, its neutralization by NaCI in the secretions, and the possible dangers of argyria. There are many excellent sub- stitutes for AgN0 3 , protargol being probably the best. Soap. According to Parkes, ordinary soap possesses marked disinfectant properties. He adds that there is little or no advantage in using soaps impregnated with small quan- tities of disinfectants. . Sulphurous Acid. The gas, S0 2 , produced by the burning of S, unites with aqueous vapor to form the strongly germicidal H 2 S0 3 . The dry gas is but feebly destructive of germs; hence the necessity of placing the sulphur dish in a vessel of water. The H 2 S0 3 thus produced kills the bacillus of anthrax in 5- per-cent. solution or non-spore-bearers in 1-per-cent. solution within twenty-four hours. For fumigation three pounds of S are required for each thousand cubic feet of space. The fumigation should last at least twelve hours, with doors and windows closed and the cracks well stuffed with cotton. 334 SANITARY CHEMISTRY. Tannic Acid. In addition to its valuable astringent prop- erties, Abbott has found that this drug is antiseptic in solutions of 1 to 400. Thymol. This stearopten has one-fourth ' the antiseptic potency of carbolic acid. It is used for respiratory affections in the form of sprays or inhalations, and externally in oint- ments for scaly skin diseases. Thymol has a pleasant odor, attractive to flies, unfortunately. Turpentine. The oil of turpentine and its derivatives, terebene and terpin hydrate, are of some power as antiseptic agents, but are too irritating for surgical ends, as a rule. Tur- pentine, in conjunction with tincture of iodin, is a very valu- able application for ringworm. Urotropin. Hexamethylentetramin is a valuable urinary antiseptic, especially after typhoid fever. It liberates formal- dehyd in the urinary passages. Vinegar. Klein and McClintock agree that dilute acetic acid (7 per cent.) is as efficient in preventing the growth of micro-organisms as is a 1 to 1000 solution of HgCl 2 . Kitasato found that a 3-per-cent. solution of the acid kills typhoid ba- cilli in five hours. Acids generally are inimical to germ-life. v QUESTIONS ON SANITARY CHEMISTRY. 1. Explain darkening of permanganate solution in the presence of reducing agents. 2. How detect Na 2 CO 3 in residue from evaporated milk? 3. What is formed when NH 3 combines with HCOH after disin- fecting a sick-room? 4. Name five oxidizing disinfectants. 5. What are the final products of the oxidation of organic matter? *6. Name two reducing disinfectants. 7. Name three coagulating disinfectants. 8. Name an oxidizing and an absorbing deodorizer. 9. How remove acidity due to C0 2 from water? 10. How does pumping considerably from a farm-well increase the amount of impurities in the water? 11. How does agitation with iron filings purify drinking-water? 12. Why is deep well water harder than rain water? 13. Why is soft water better than hard for boiling meat and vege- tables? 14. Are plants in sleeping-rooms healthful or not? 15. To test the air of a certain room quantitatively for C0 2 , if the flask is brought from without the room, how can you empty the air already in it and fill it with the air of the apartment to be tested? 16. What is the yellowish color produced by nesslerizing? 17. Why should all cellars be cemented? 18. With a blotting-paper and suitable reagents how could you prove the presence in the air of NH 3 , H,S, ozone, SOj, or Cl? QUESTIONS. 335 19. Why is the presence of NH 4 compounds in deep water of less serious significance than in surface- or subsoil- waters? 20. How prove the presence of alum in a baking-powder? 21. Explain the corrosive effect of HgCl 2 on surgical instruments. 22. How much carbolic acid is needed to disinfect a pint of tuber- culous sputum? 23. How often should the air be changed in a sleeping-room 12x14x8, occupied by man, wife, and child? 24. Describe the changes which organic matter undergoes in the soil. 25. Write equation for the reaction between oxalic acid and potas- sium permanganate. 26. What objection to throwing much chlorinated lime down drains? 27. The pharmacopeial limit of K 2 C0 3 in KBr is 0.138 per cent. Directions are given to add to 1 gm. of the salt in 10 c.c. of water 0.02 c.c. of normal H 2 S0 4 , after which phenol-phthalein should give no color unless the carbonate is in excess. Give reasons. | TOXICOLOGY. DEFINITION. To DEFINE a poison is about as difficult as to explain the signification of a weed. All medicines of any strength what- ever may produce toxic effects; in fact, with the ancient Greeks the same word was used to express both a poison and a medi- cine. A pound of common salt, taken for tapeworm, has caused death by its paralyzing effect upon the nervous system. Per- haps the best definition of a poison, then, is any substance which acts injuriously within and upon the human body, and is capable of causing death in a way not merely mechanic. Thus an injury or boiling water or steam may prove fatal, but, being mechanic in nature, they should not be classed as poisons. ACUTE POISONING. Poisons may be introduced into the body by the mouth, lungs, rectum, vagina, skin, or by hypodermic or intravenous injection. Toxic agents that are most soluble and diffusible are most rapidly fatal, especially when inhaled or injected in- travenously. Insoluble substances have no action on the sys- tem until they have been more or less dissolved by the digestive secretions. A few poisons (curare, snake-venom, and the virus of syphilis, glanders, and small-pox) are comparatively harmless when swallowed, though most deadly when introduced directly into the blood, as through a bite or wound. A full stomach may delay the absorption of a poison, and consequently the toxic symptoms, for several hours. The circulating poison is gradually eliminated (As in fifteen to thirty days), a part hav- ing been stored up in the tissues for a variable period. It is believed that toxic effects are due entirely to that portion of the poison present in the capillaries. Gaseous poisons appear to be eliminated almost instantly by the lungs, no matter how introduced. A poison may gain entrance into the human sys- tem through the body of an animal without the latter being affected by it. Thus, cows and goats feed on stramonium with impunity, yet their milk becomes poisonous to human beings. How shall we determine that a person has been poisoned, (336) ACUTE POISONING. 337 accidentally or feloniously? Usually by th*e sudden advent of suspicious symptoms shortly after taking food or drink, if acci- dental or homicidal; if suicidal, traces of the poison itself, and not infrequently the container, are to be found. In most cases the individual affected has been in previous good health. Symptoms of poisoning may be masked by alcoholism or sick- ness. The most common symptoms of acute poisoning are vio- lent pain, vomiting, purging, convulsions, delirium, and drowsi- ness: one or a few or all of these. It must not be forgotten, however, that toxic symptoms are simulated by many diseased conditions. Thus, cholera, cholera morbus, perforative peri- tonitis, ileus, and hernia resemble acute As poisoning as to the pain, vomiting, and purging; strychnin poisoning^closely simu- lates tetanus; and coma is the foremost symptom in apoplexy, alcoholism, and insolation, as well as in opium poisoning. Even the post-mortem appearances of disease may resemble those found after death from poisoning, and the poison may indeed have been introduced into the body after death, as by embalm- ing processes or by injection into the stomach or the rectum. In the latter event some of the poison will pass by osmosis into the liver and other adjacent viscera. Suffocation by in- halation of vomited matters is often the direct cause of death in alcoholism and CO poisoning. Circumstantial evidence, such as finding poison in the food or drink, is of great importance, but is not absolutely conclu- sive. The ordinary chemic tests are generally sufficient for revealing the presence of a poison in a body, but one must bear in mind how closely certain ptomains resemble in reaction the vegetable alkaloids. To separate inorganic substances for chemic analysis boil the finely minced stomach or other matters with HC1 and crystals of KC10 3 until a straw-colored liquid results; treat this with NaHS0 3 till a distinct odor of S0 2 is noted; then pass H 2 S through the concentrated liquid, throw- ing down most metals as sulphids, from which a bead is readily obtained by reduction. Such destructive methods cannot be used for isolating organic compounds. Dialysis is a ready means of separating crystalloid poisons from the colloids in the stomach or intestines. Microchemic methods are of special service in medico-legal cases. In case of doubt physiologic tests should be made upon living animals, with control tests with equivalent amounts of the substance suspected to be present. Distillation is indicated in the separation of HCN" and other volatile compounds. Alkaloids are isolated by acidulating the suspected material, heating carefully over the water-bath, filter- 338 TOXICOLOGY. ing, washing with -boiling distilled water, evaporating the fil- trate, rubbing up residue with distilled water, and again filter- ing until a fairly pure product is obtained; then neutralizing with NaHC0 3 , taking up freed alkaloid with ether or chloro- form and evaporating spontaneously, leaving the pure alkaloid ready for testing. Stas's method for separating morphin and strychnin from other substances is to render the vomit alkaline with Na 2 C0 3 and shake liquid with four volumes of ether or amylic alcohol (best for morphin); let fluids separate, remove ethereal or alco- holic solution, and allow to evaporate. The local effects of poisons include erosion of mucous membrane (mineral acids and caustic alkalies), irritation or inflammation (irritant poisons generally), and special sensa- tions, such as the tingling of the tongue produced by aconite, the dry throat of belladonna, and the local anesthesia of cocain. The mouth is bleached in poisoning by carbolic acid, HgCl 2 , AgN"0 3 , potash, or soda (mucosa swollen, translucent, brown, and soapy). The odor of the drug on the breath is perceptible in poisoning by HCN, laudanum, alcohol, phenol, creasote, chloroform, I, P, camphor, nitrobenzol, NH 3 , and acetic acid. Certain poisons have an elective affinity for various organs, as strychnin for the spinal cord, prussic acid for the heart, and opium for the brain. The remote effects of poisons are either common, as fever, or specific. Thus, the pupils are dilated by belladonna, atropin, hyoscyamus, stramonium, aconite, alcohol, chloroform, conium, and opium (last stage). They are contracted by opiates, eserin, phenol, or chloral (during sleep). Coma is noted with opiates, alcohol, chloral, chloroform, carbolic acid, and camphor. The chief deliriants are the nightshade family, cannabis Indica, alco- hol, and camphor. Convulsions are common symptoms with nearly every kind of poison, being probably due to reflex action, in the same way as teething or worms may excite them. Te- tanic spasms are observed with nux vomica or strychnin, and less often from brucin, Sb, As, or even intense pain. Paralysis may occur in poisoning by eserin, conium (from below upward), aconite, and in chronic metallic poisoning. The mouth and tongue are dry in belladonna, hyoscyamus, stramonium, and opium poisoning. Salivation may be due to Hg, As, NH 3 , pilo- carpin, muscarin, cantharis, and corrosives generally. The skin is dry in poisoning by any of the nightshade family. It is moist in poisoning by opium and depressants generally (aconite, alco- hol, tobacco, lobelia, Sb, etc.). A scarlet rash is noted in bella- donna or stramonium poisoning and in ptomain poisoning from ACUTE POISONING. 339 decayed meat or fish; urticaria in opium, chloral, cubebs, and salicylic acid; eczema from As; acne from tar or KBr; pustular eruptions from Sb or croton-oil; petechias from KI. The blood is turned carmin by CO and KCN; dark by HCN; brick-red (in contact) by carbolic acid; black in contact with HN0 3 ; chocolate-brown, with destruction of red cells, by KC10 3 and other reducing agents; dark and free from clots in alcohol and narcotic poisoning and all conditions causing death by asphyxia (nitrobenzol, strychnin, belladonna, most glucosids, KC10 3 , K 2 Cr 2 7 ) or syncope (aconite, digitalis). The medico-legal duties of the practitioner in cases of sup- posed poisoning are: first, to preserve the life of the patient if possible; and, second, to forward justice by writing down his observations on the case as quickly as practicable. He should also take charge of any suspected food, medicine, vomit, urine, or feces, and seal them in new, clean vessels duly labeled for examination. In the post-mortem examination (preferably within twenty- four hours) a double ligature should be passed around the esophagus in the chest, and another around the duodenum a few inches below the pylorus. The stomach is removed intact by cutting between each pair of ligatures, and is opened along the lesser curvature as soon as possible and its lining spread out and examined with a hand-lens for particles of poison. Another ligature should be tied low down in the rectum and the intestine removed to a separate clean vessel and scrutinized carefully. As much blood as possible should be secured for the chemist; also a part or the whole of the liver, brain, spinal cord, kidney, spleen, and thoracic viscera, and a large piece of muscle from the thigh or a portion of bone. In corrosive poisoning the mouth, esophagus, stomach, and duodenum should be removed together. Poisons are found in their greatest purity in the kidneys and urine. The normal vivid congestion of the stomach after meals and the common post-mortem suffusions and auto- digestion of the stomach ought not to be mistaken for toxic lesions. Perforation due to a corrosive differs from the small aperture of disease in being large and ragged, with soft, friable edges. The post-mortem examination should be as thorough as possible in order to discover if the sudden and fatal end were not due to some latent disease; for instance, to the perforation of an unrecognized gastric or typhoid ulcer. The mouth, lips, and tongue should be carefully examined for stains or erosions, and the skin for hypodermic punctures. Decomposition of organs is best prevented by freezing, but 340 TOXICOLOGY. pure alcohol may be utilized if necessary. The presence of As in appreciable quantities retards putrefaction for long periods. The jars should be sealed by attaching tape to both jar and cover by means of sealing-wax, the seal being retained, and a signed and dated label should be placed on each jar. For practical purposes acute poisons may be divided into three main classes: corrosives, irritants, and neurotics. The first two affect principally the alimentary tract; the last, the nervous system. Corrosive poisons differ from irritants mainly in the intensity and rapidity of the symptoms, and a drug may be either irritant or corrosive according to the amount ingested or the degree of dilution. The cause of death from irritants is gastro-enteritis, with or without specific remote effects. Cor- rosives cause death by acute laryngitis with edema, perforation of stomach, gastro-enteritis, shock, or slow starvation. Neurotic poisons have been subdivided into a number of varieties corresponding with the leading or selective action of the various drugs. Narcotics (opium, for example) act chiefly upon the brain, causing stupor and finally death from paralysis of the vital nerve-centers. Anesthetics produce fatal effects in the same manner, or indirectly by mechanic interference with respiration, as when a patient chokes to death from vom- iting of bronchial mucus. The third stage of alcoholic inebria- tion, like that of anesthesia, is simply a narcosis, and should be treated in the same manner as the latter. The solanaceous deliriants act chiefly on the brain, producing delirium. Some neurotics (strychnin, for example) cause death by tetanic fixa- tion of the muscles of respiration. The opposite condition of motor paralysis is noted with conium, curare, and Calabar bean. Others, like aconite and prussic acid, lead to death by syncope: that is, cardiac paralysis. A lethal result may follow over- stimulation of the heart, leading to exhaustion, as in the case of digitalis. Most irritant poisons belong to the mineral kingdom, whereas nearly all neurotics are of vegetable origin. Animal poisons taken by the mouth usually act as irritants; when re- ceived directly into the blood, as in dissection wounds, they play the part of depressing neurotics. Poisonous gases owe their injurious effects either to an irritant congesting action, as Cl and Br; to chemic decomposition of the blood, as CO and H 2 S; or to a depressing influence upon the respiratory center, as C0 2 . The treatment of ordinary irritant poisoning consists, in general, of the following steps: 1. The administration of the chemic antidote, which means any safe and proper substance that will form, with the poison, an insoluble or innocuous com- ACUTE POISONING. 341 pound. 2. The production or encouragement of emesis, or emptying the stomach with the siphon rubber tube or pump. If the tube is employed, the stomach may be washed out with a solution of the antidote or with diluted milk or some other soothing liquid. The best systemic emetic is apomorphin hydrochlorate, of which y i5 to 1 / 10 grain (for an adult) may be injected hypodermically, and be repeated, if necessary, within twenty or thirty minutes; this drug will evidently be of no avail in deep narcosis, in which condition we use preferably the tube or pump. In the absence of the above-mentioned means of emesis, we may employ tepid or greasy water in quantity, or a dessertspoonful of ground mustard or common salt in a glass of warm water, or ZnS0 4 , 20 to 30 grains (5 grains for children) in water, or for children a teaspoonful of syrup of ipecac; the simple operation of tickling the fauces is likewise not to be despised as a means to the end. 3. The administration of demulcent drinks to allay irritation and pre- vent., to some extent, the further injurious action of the poison. Mucilaginous (linseed, acacia, barley, starch paste, oatmeal- gruel) and albuminous (eggs and milk) preparations serve a useful purpose here. 4. Emptying the bowels of any poison that may be retained there, as well as of the antidotal com- pounds, which would gradually undergo solution and absorp- tion. Castor-oil (a tablespoonful) and Epsom salts (1 to 4 ounces) are most generally useful. Croton-oil, 1 to 5 minims on a bread pill, is quite efficient. Senna, gamboge, and other drastics are best in narcotic poisoning. 5. Allaying pain by hot external applications and morphin hypodermically. 6. Combating shock with the stimulants at hand and doing what- ever else judgment and common-sense would dictate. In the treatment of corrosive poisoning we use preferably, if anything, the soft-rubber tube for emptying the stomach, on account of the danger of rupture of the weakened walls. Neu- rotic poisons require, in addition to antidotes and evacuation, the administration of their respective physiologic antagonists, as chloral and chloroform against strychnin; atropin and caffein against morphin; brandy against aconite, etc. It is well to be careful in this connection so as not to substitute one kind of neurotic poisoning for another, and, generally speaking, not more than the physiologic dose of the opposing drug should be exhibited. In the treatment of acute poisoning time is a very impor- tant factor, and the measures employed should be as rapid and energetic as possible. It will frequently occur that some of the more eligible antidotes are not at hand, nor to be had in a 342 TOXICOLOGY. very short time. While waiting for their arrival it is well to use at once such other remedial methods as knowledge and judgment will dictate. Like other derangements of the bodily functions, every case of poisoning must be treated on its pecul- iar indications, and no amount of information can take the place of intelligent presence of mind. ANTIDOTES IN GENERAL. Magnesia, 1 part to 25 of warm water (1 1 / 2 to 2 ounces at short intervals), is the most efficient antidote against acids and acid salts, and is also valuable in poisoning by metallic salts, such as arsenic. Calcium hydrate and carbonate (lime- water, chalk, egg- or oyster- shells) are also good antidotes for acids, especially oxalic, and oxalates. The carbonates and bicar- bonates of Na and K may be used against most poisonous metallic salts, particularly those of zinc. They are also useful against K 2 Cr 2 7 , forming the neutral chromate. Ferric hy- droxid is the antidote par excellence (10 to 1) for arsenic. Soap- suds (1 to 4 of water) by the cupful is a most effective antidote against corrosive acids and salts. Copper carbonate, 3 to 6 grains with sugar and water, preceded and followed by an emetic, is recommended for P poisoning. Dilute H 2 S0 4 is used as an antidote for soluble salts of Pb and Ba. Diluted NH 3 by inhalation is useful against vapors of corrosive acids, nitro- benzol, Cl, Br, and HCN. Sodium hyposulphite, 15 grains in very dilute solution frequently repeated, is a good antidote for bleaching powder and other hypochlorites. Gum arabic in copious draughts is recommended against toxic symptoms from Bi salts. Starch paste (1 to 15) neutralizes I and Br. Oils and fats are efficient antidotes for caustic alka- lies and metallic oxids. They should be avoided in poisoning by P, carbolic acid, cantharis, or Cu salts. Weak vegetable acids are of service against corrosive alkalies. Albumin is an ideal antidote for most metallic salts, and is effective against acids, alkalies, I, Br, Cl, creasote, anilin, and alcoholic solutions of alkaloids. It should be given well diluted (whites of 4 eggs to a quart of tepid water) and be followed by emetics and cathar- tics: Milk is a good substitute for egg-albumin, but is contra- indicated if fats are. Tannic acid (15 to 45 grains in a 2-per-cent. solution every quarter-hour) is an efficient chemic antidote for all alkaloidal salts and for tartar emetic. Its effect is enhanced by the addi- tion of 10 per cent, of I. As a household remedy, it may be given in the form of a strong infusion or decoction of green tea. CORROSIVES. 343 K 2 Mn 2 8 , grain for grain of the poison and well diluted, is useful as an oxidizing agent against all organic compounds, when the poison is still in the stomach. Animal charcoal has also been used as an antidote for alkaloids, which it renders more or less inert by absorbing them. Iron filings are antidotal to Cu or Hg poisoning. If the nature of the poison is quite unknown, a harmless and useful antidote is made with equal parts of magnesia, wood- charcoal, and ferric hydrate, given freely in plenty of water. CORROSIVES. The general symptoms of corrosive poisoning are severe and immediate burning pain in the mouth, throat, stomach, and abdomen (increased by pressure); staining and erosion of the mucous membrane of the mouth and throat; vomiting of stomach-contents, mixed with mucus and blood, and often fol- lowed by bloody purging (constipation with mineral acids); dysphagia, dyspnea, aphonia; headache and marked prostration pulse small and weak, skin cool and sweating; convulsions common; painful cramps in calves; urine scanty or suppressed; mind usually clear; peculiar drawn, haggard facies. Common sequels in case of recovery are nephritis and esophageal stricture. MINERAL ACIDS. These include nitric, hydrochloric, sulphuric, phosphoric, and chromic. All produce acid vomit and dry eschars. The tissues are stained yellow by nitric; white or grayish, turning brownish, by hydrochloric; light yellow, becoming gray-brown, by chromic; dark gray-brown and deep eschars by sulphuric acid. The vomit is brown with nitric acid; dark yellow with hydrochloric; dark with sulphuric; and yellow-red or green with chromic. Black woolen cloth is stained yellow by nitric acid (quickly burns a hole); bright red or green by hydro- chloric; wet red by sulphuric. The smallest fatal dose of mineral acids ranges from 1 dram H 2 S0 4 to 4 drams HC1; less than 1 / 2 grain of Cr0 3 has proved fatal. The usual period of death is from eighteen to twenty-four hours, though much sooner if the acid acts directly on the respiratory apparatus. The best antidotes for the min- eral acids are mild alkaline drinks ad libitum, such as lime- water, soap-suds, and heavy magnesia suspended in milk. If these are not at hand, give lime from the walls, chalk, or 344 TOXICOLOGY. baking-soda. Dilute the acid with plenty of water. Small pieces of ice may be given for too severe retching. Coma may be opposed by subdermic injections of ]Sra 2 C0 3 . For external vitriol burns soda is a good antidote after wiping off the acid with a dry cloth. VEGETABLE ACIDS. These also produce acid vomit and dry, white eschars. Oxalic acid is characterized by a very sour taste; it may pro- duce coma or tetanic convulsions. It causes an orange stain on black cloth. A dram has produced death within an hour. Acetic acid is distinguished by the odor of vinegar. Tartaric acid yields a burnt-sugar odor on heating. Lime-water is a good antidote for all three vegetable acids, particularly for oxalic. Other antidotes are magnesia, soap-suds, chalk, baking- soda, wall-plaster, whiting, and tooth-powders. CAUSTIC ALKALIES. This class includes alkaline hydrates and oxids and car- bonates (lye, washing-soda, sal volatile). They produce brown- ish, ropy, alkaline, mucous, bloody, soapy, frothy vomit and wet, sloughing sores. They have a very acrid, burning taste. CEdema glottidis is very liable to be caused by ammonia. Strong hydrates leave a brown stain on black cloth. The small- est fatal dose on record is 40 grains of potassa. Death usually takes place within a few hours. Caustic alkalies are safely and readily neutralized by an abundance of any fixed oil (linseed, almond, olive, cotton-seed) or fat (butter, lard), forming thereby a soap. Weak vegetable acids, such as lemon-juice or orange-juice and vinegar, fulfill similar indica- tions, but less acceptably. Demulcent drinks should be given freely. Emetics and the stomach-pump are contra-indicated. CHLORIDS. Corrosive sublimate may produce toxic symptoms as bed- bug poison, antiseptic tablets, or vaginal douches. It has a styptic, metallic taste, and coats the lips and tongue white. The vomit is glairy or bloody. Cramps of the extremities are common. It corrodes and darkens metals. The smallest fatal dose on record is 3 grains; time, one-half to five days. White of egg is the best antidote, 1 for every 4 grains. The resulting albuminate should be removed quickly to prevent its solution in the digestive juices. Death is due to collapse, coma, or con- vulsions. IRRITANTS. 345 The butter of antimony causes grumous vomit, violent purging, and great depression. The chlorid of zinc, used in soldering and embalming fluids, has killed in the dose of 6 grains. Baking-soda in plenty of water, as well as eggs or milk, is indicated. NITRATES. Saltpeter causes frequent urination, tremors, convulsions, delirium, prostration, or collapse. An ounce of it has caused death in about two hours. Lunar caustic shows a glazed appearance of the mucous membrane, and the vomit darkens on exposure to light. Fifty grains has caused death. Common salt is the antidote. PHENOLS. Carbolic acid produces hard, white patches in the mouth, frothy vomit, contracted pupils, blackish-green urine, speedy coma, and collapse. The breathing is slow and deep at first; shallow and hurried toward the end. The breath has the pecul- iar odor of the acid, which gives a violet color with Fe 2 Cl 6 . A half-dram has proved fatal; the period of death ranges from one-half to twelve hours. Alcoholics serve as the choice of antidotes, and further as needed stimulants. Epsom or Glauber salts are also useful remedies. The stomach should be cleared out quickly with the tube or apomorphin. Oils and fats must be avoided. Other phenols which may produce poisonous effects are cresols, creasote, guaiacol, salol, and creolin. IRRITANTS. The symptoms of irritant poisoning are similar to those of corrosives, but are generally less intense, and do not come on for some minutes or hours. Great thirst, severe headache, giddiness, cramps in the legs, torpor, coma, and convulsions are common symptoms. Dilute mineral acids and other corrosives may act as irritant poisons. MINERAL. Arsenic is present in white arsenic, fly-paper, fly-powder, "Hough on Rats," Scheele's green (candy, wall-paper), Paris green, cancer cures, colored crayons, and artificial flowers. Special symptoms of arsenical poisoning are the suffused and reddened eyes, brown vomit often mixed with bloody mucus, 346 TOXICOLOGY. bloody or choleraic stools with tenesmus, subnormal tempera- ture, and prominent nervous symptoms. The skin is cold and clammy. The urine is often partly suppressed. Pain is gen- erally severe, but may be slight or 'absent; numbness and tingling are complained of. The symptoms usually begin in from fifteen to sixty minutes. The smallest fatal dose was 1 1 / 2 grains; fatal period, two to twenty-four hours; average, ten. A simple test for As is the garlicky odor noticed on heating the powder, or the lemon-yellow ppt. with H 2 S. After thoroughly emptying the stomach with the pump, tube, or emetic, one should neutralize the remaining poison that cannot be washed away. This is done by means of mag- nesia with freshly made magma of ferric hydrate (made by mixing equal parts of tincture of iron and ammonia-water, and straining and washing the precipitate), of which the dose is a tablespoonful every half-hour for four to six doses. This forms insoluble Fe 3 (As0 4 ) 2 . Demonstration of Antidote for Arsenical Poisoning. Render Fe 2 Cl 6 solution alkaline with NH 4 OH, throwing down ppt. of Fe 2 (HO) on a cloth; wash clear of NH 3 , and then stir the ppt. into a beaker con- taining an arsenic solution. After five minutes filter and prove absence of As in filtrate. Another good antidote for arsenic is dialyzed iron. Stimu- lants (brandy, aromatic spirit of ammonia, strychnin) should be given hypodermically for faintness, and, if the patient is cold, use hot blankets. After the sickness subsides an ounce or two of castor-oil should be given. Antimony poisoning is characterized especially by excessive vomiting and depression; also by a strong metallic taste, by early salivation, profuse sweats, and rice-water stools. The urine is usually increased, with painful micturition. Two grains of tartar emetic have caused death. Tannin is the best antidote; ferric hydrate is next best. Encourage vomiting with warm drinks, stimulate freely, and keep patient warm with hot blankets and bottles. Acute lead poisoning is manifested by intense abdominal pain, with hard, retracted abdomen and constipation; the stools are black. If the case is protracted, local paralyses and the blue line on the gums appear. Any lead salt or solution turns black with H 2 S; lead salts are also easily reduced to a bead. One ounce of sugar of lead has proved fatal. Any sulphate (preferably MgSOJ will ppt. Pb solutions and act as an anti- dote. A hypodermic of morphin will usually be required for the pain. IRRITANTS. 347 Copper poisoning (blue vitriol, verdigris) excites greenish vomit and a very marked metallic taste. In acid solution me- tallic copper is pptd. on a knife-blade. Milk and eggs are antidotes. The chlorid of tin used in dyeing has sometimes given rise to toxic effects. It is more depressant than irritating. A frag- ment of Zn ppts. the metal in arborescent form. Milk and eggs are in order; magnesia is also an antidote. Both copperas and tincture of iron have caused death when taken in very large doses (1 Y 2 ounces of tincture). Iron solutions turn black with tannin or tea, and cause a dark- greenish fur on the tongue. Baking-soda or magnesia and milk and mucilaginous drinks are indicated. Common alum in very large doses may produce toxic symptoms. It has a sweetish, styptic taste, and there is some- times frothing at the mouth. The chief antidotes are milk and baking-soda. Zinc sulphate in large doses causes excessive vomiting, dilated pupils, and coma. One-half ounce has proved fatal in about twelve hours. Vomiting should be encouraged by copious draughts of warm water. Antidotes are lime-water, albumin, soap-suds, and tannin. Potassium dichromate has caused death in a number of instances, 2 drams being the smallest fatal dose. The vomit is yellow, the pupils dilated, and there is violent purging. Am- monia-water gives a green ppt. Lime-water or magnesia and milk are good antidotes. Barium salts cause nervous symptoms, cardiac palpitation, disturbed vision, and great weakness. One dram has proved fatal. Epsom or Glauber salts are purgative antidotes, and should be followed by emetics and by fixed oils to soothe. The flame test is greenish. The chlorate, sulphate, and bitartrate of potassium are all capable of exciting toxic symptoms; 4 drams of chlorate have caused death, and 1 1 / 2 ounces of cream of tartar likewise. The chlorate is marked by rigid limbs, delirium, coma, and bloody urine. The bitartrate poisoning resembles that by niter. So- dium bicarbonate neutralizes the bitartrate. Opium, stimu- lants, and demulcents are called for. Bleaching powder taken internally acts as an irritant poison. It has a sharp, acid taste and a distinct odor of chlorin. It is best counteracted by lime-water and oils. lodin solutions in large doses are marked by an acrid taste, tightness about the throat, pain, vomiting, and purging; yellow stains are noted on the mucous membrane. Starch or flour in 348 TOXICOLOGY. warm water should be given till the blue color disappears from the vomit. White of eggs and milk should follow. Phosphorus .poisoning may occur from swallowing match- heads, ratsbane, or phosphorated oil, or by inhalation of phos- phine. Special symptoms are a garlicky odor and taste; grad- ually increasing pain, beginning over the region of the liver within an hour to several days; jaundice on second or third day; muscular twitchings; albuminuria, hematuria, or sup- pressed urine (contains leucin and tyrosin); paralysis, coma, and collapse. The vomit is greenish or coffee-ground in color, and both it and the stools are luminous in the dark, especially on heating with sulphuric acid. One-fiftieth grain has caused death in from one to four days. There is no direct antidote for phosphorus. Useful oxidizing agents are potassium per- manganate and ozonized turpentine ("French oil," 1 / 2 dram every half-hour for five or six doses). As an emetic, copper sulphate is commonly used: 3 grains well diluted every fifteen minutes till vomiting occurs. Albuminous and mucilaginous drinks and milk or magnesia should be given, but no oils or fats. Oxygen inhalations are recommended. Post-mortem ex- amination shows fatty degeneration of the liver, kidneys, heart, and other muscles. Demonstration of Antidote. Place a bit of P in CuSO 4 solution for a few minutes, and note, on removal, the coating of Cu on the piece of P. VEGETABLE. Many resins (aloes, jalap, gamboge, scammony, bryony, elaterium) in too large doses cause excessive mucous purging, with intense griping pain and considerable depression. The stomach should be emptied and castor-oil given. Morphin hypodermically, mucilaginous drinks, emollient enemata, and hot fomentations are also useful. It is important to counteract great exhaustion. Certain oils (savin, croton, castor, turpentine) may excite choleraic vomiting and purging, with contracted pupils, ster- torous breathing, strangury, and collapse. Fifteen minims of croton-oil have proved fatal. The white of eggs is the chief antidote. Epsom salts are useful against turpentine, for which hot fomentations to the loins are also serviceable. Brandy, aromatic ammonia, or other stimulant may be needed. Colchicum preparations sometimes produce violent purg- ing, with dilated pupils, cold skin, dyspnea, and rapid exhaus- tion. Tannin or strong tea or coffee ppts. the active principle, and stimulants are necessary. IRRITANTS. 349 Black, green, and white hellebore or veratrum has a very acrid and bitter taste, and causes, in poisonous doses, violent vomiting, purging, and abdominal pain, with marked depres- sion. It is treated like colchicum poisoning. Ergot, or the fungus of rye, often taken to produce abortion, causes dizziness, headache, mydriasis, dyspnea, delirium, coma, and heart-failure. It has a peculiar, nutty odor. Tannic acid is the antidote. Xitroglycerin is of service, and small doses of opium may be given after the stomach and bowels are emptied. The patient should be kept warm in the recumbent posture. The symptoms of digitalis poisoning are chiefly a feeble, slow, intermittent pulse; nausea, grass-green vomiting, and purging; abdominal pain, vertigo, pale .face, dilated pupils; severe headache, delirium, syncope; cold, clammy skin; chro- mopsia, cyanosis, convulsions, paralysis, coma. Death occurs from sudden heart-failure. Poisoning usually takes place from the cumulative effect of the drug given in repeated doses, rather than from a single large dose. The main point in treat- ment is to keep the patient in a horizontal posture. Brandy is useful, and aconite may be tried in very small doses and re- peated if beneficial. Tannin or strong tea should be given to antidote the glucosids. Lathyrus, or vetches, are marked by an initial chill, pain in the loins and legs, a girdle sensation, paresthesia, lameness, and gangrene. All parts of the yew- and laburnum- trees may cause toxic symptoms, such as vomiting, abdominal pain, narcosis, con- vulsive movements, and dilated pupils. They have a sweet taste. Cytisin warmed with nitric acid gives an orange-yellow color. ANIMAL. Cantharis, or Spanish fly, used either internally or exter- nally, may cause a dull pain in the loins, vesic tenesmus, stran- gury, priapism, salivation, and bloody vomit, stools, and urine. It blisters skin or mucous membrane. One should look for the shining gold-green wing-cases of the insects with a hand-lens. One ounce of the tincture has resulted fatally. Give plenty of water and a warm bath; empty the stomach and give castor-oil. Charcoal, linseed-tea, mucilage, milk, morphin, and stimulants (by the rectum) are all of service. Botulismus (sausage or meat poisoning) is characterized by dry mouth, vomiting, purging, constricted throat, vertigo, di- lated pupils, ptosis, suffocation, fever, erythema, thready pulse, and collapse. The putrid section of meat looks dirty grayish 350 TOXICOLOGY. green, soft, and smeary. The chief indication is to wash out the stomach and intestines as thoroughly as possible. Mor- phin, atropin, and strychnin may also be required. Galactotoxicons, or milk-poisons, are saprophytes causing the summer diarrheas of infants, with vomiting, prostration, and stupor. The chief indications are to stop the milk, give white of egg and water, and flush the stomach and bowels fre- quently with normal saline solution. Tyrotoxicon (diazobenzene) is a poison sometimes formed in cheese, ice-cream, custard, and cream-puffs. It produces dry- ness and constriction of the throat, purging, vomiting, weak pulse, nervous prostration, and delirium. Thorough washing of the stomach and intestines should be performed, and hypo- dermic injections of strychnin, brandy, or ammonia will prob- ably be needed. Ichthyotoxins, or fish-poisons, may be present in canned fish, mussels, or "kakke." The symptoms are vomiting, purg- ing, dyspnea, fever, scarlatinous or urticarial rash, often dilated pupils, painful cramps in the limbs, marked prostration, con- vulsions, delirium, and insensibility. The treatment is the same as above. GASES. The more common acid vapors are bromin, chlorin, hydro- chloric acid, and nitrous and sulphurous fumes. They excite coughing and suffocation, conjunctival and pharyngeal conges- tion, trembling and weakness. The concentrated gas may pro- duce an immediate fatal result by closure of the glottis and asphyxia. The peculiar odor and color of the fumes aid in the diagnosis. Weak ammonia by inhalation is the antidote. Fresh air and rest are most important. Congestion of the lungs should be relieved, if necessary, by counter-irritants. Alkaline vapors, such as strong ammonia, produce the same symptoms as acid vapors, with perhaps more burning in the throat and with vomiting and giddiness. Vinegar inhalations are antidotal. Otherwise the treatment is the same as for acid gases. NEUROTICS. The members of this class act principally on the nervous system, after absorption, the symptoms usually beginning in about a half-hour. The class is variously divided into several varieties, the simplest arrangement being into narcotics, de- pressants, and convulsants. NARCOTICS. 351 NARCOTICS. These are characterized chiefly by stupor, delirium, and insensibility, the latter supervening in from five minutes to many hours. Convulsions may occur. The treatment in gen- eral for narcotic poisoning is to give as an antidote for all the alkaloids tannic acid or strong green tea, or potassium perman- ganate grain for grain of the poison (the stomach may be washed with a solution of permanganate, 2 to 4 grains to the pint). Charcoal is also of some service as an antidote. The physiologic antagonists most indicated are caffein (or strong coffee by the rectum or mouth), atropin (Vi2o grain every fifteen minutes for three doses in morphin or opium poisoning), am- monia, strychnin, brandy, and amyl nitrite for heart-failure; morphin (till pupils begin to contract) and pilocarpin ( l / 2 grain) for belladonna, atropin, or other solanaceous poisons; and faradism of the phrenic nerve in the neck. The stomach should be emptied with tube, pump, or emetics (mustard is very good). Slap the chest with towels wrung from cold water; apply cold to the head and warmth to the extremities. Keep the bladder empty to prevent resorption of the poison. Artificial respira- tion may be needed for a time. In opium poisoning the patient should be kept awake by walking him about. For alarming symptoms during anesthesia invert the patient, hold up the base of the tongue, clear the fauces, inject stimulants, use nitrite of amyl by inhalation, and employ artificial respiration. Atropin and caffein are the most generally useful stimulants. Opium poisoning may take place by way of morphin, co- dein, laudanum, paregoric, soothing and cough syrups, poppy- tea, Dover's powder, black drop, Godfrey's cordial, McMunn's elixir, etc. One grain of morphin by the mouth, 4 grains of opium, and 2 drams of laudanum have each proved fatal. The usual fatal period is from three to twelve hours, the earliest having been forty-five minutes. The leading symptoms are staggering, excitement, then coma; pin-point pupils (may be dilated toward fatal end); slow, full pulse, becoming weak and irregular; slow, stertorous breathing, becoming feeble and of the Cheyne-Stokes type. The face is congested, becoming paler; the skin is cold and clammy and may show urticaria or itching. Convulsions are common in children, and may be tetanic in nature. Children are particularly susceptible to opiates. Belladonna or atropin poisoning exhibits symptoms which are almost entirely opposite, namely: dilated pupils and rapid pulse and respiration. There is active delirium; sometimes 352 TOXICOLOGY. high fever; hot, dry skin, throat, and fauces; and may be strangury and suppressed urine. A drop of the patient's urine instilled into the eye of a dog or cat will dilate the pupil in a few minutes. One-half grain of atropin has caused death. Poisoning by hyoscyamus, stramonium, or solanum (potato- sprouts) shows similar symptoms. Hyoscin is a muscular paralyzant. Stramonium excites cardiac irregularity and furi- ous delirium. Cannabis-Indica preparations have never caused death, but often produce alarming symptoms, particularly dilated pupils and exaltation of the senses. Minutes seem hours, and there may be joyous delirium or double consciousness. In addition to brandy and strychnin, lemon-juice freely is advocated. Muscarin is the active principle of poisonous mushrooms or toad-stools. These, when swallowed, produce gastro-en- teritis; vertigo; dim vision; marked myosis; intense dyspnea; feeble, rapid pulse; marked delirium; tremors, epileptiform attacks; lethargy, and coma. Pieces of the fungi may be found in the vomit. Death may occur in from two to one hundred hours. Emetics and warm water to aid vomiting, castor-oil and enemata, tannin, atropiri, and coffee will do the most good. Alcoholic coma is manifested by gradual stupor; snoring breathing; fixed, dilated pupils; and a ghastly, suffused, or bloated face, with livid lips. There is an alcoholic or ethereal odor of the breath. Two and one-half ounces have proved fatal in from six to ten hours. Ammonium carbonate, capsicum, and coffee are of special value. Chloral poisoning ("knock-out drops") is manifested by complete muscular relaxation; slow, feeble, irregular pulse and breathing (sometimes stertorous); subnormal temperature; pale or livid face; abolished reflexes; and an odor like bananas or pears. Chloral heated with caustic alkali yields the odor of chloroform. Death has been caused by 7 V 2 grains of the hy- drate in from a few minutes to a day. Aromatic ammonia, strychnin, coffee, brandy, and amyl nitrite are useful agents. Mustard plasters may be used over the heart and the calves of the legs. Artificial respiration should be kept up for hours, if necessary. Test for Chloral. Take */, test-tubeful of the urine"; add a drop of anilin oil and a finger-breadth of an alcoholic solution of NaHO. Heat, and, if chloral be present, the disagreeable odor of isocyanphenyl is noted. Death by chloroform inhalations is due apparently to vasomotor paralysis. Sudden marked dilation of the pupils, NARCOTICS. 353 not reacting to light, is a danger-signal of importance. The breathing becomes shallow and the pulse feeble and frequent. As little as 15 minims has caused sudden death in persons with weak heart. By the mouth a dram has caused death in a boy of four years. Atropin is of special service in stimulating the sympathetic. Sodium bicarbonate is the antidote for poisoning by the mouth. Death under ether is generally from asphyxia, indicated by shallow breathing, rapid pulse, and cyanosis. The pupils are usually dilated. An ounce has caused death. The most impor- tant indications are to clear the throat of mucus and employ artificial respiration. Large doses of camphor may excite toxic symptoms, such as burning pain in throat and stomach; foaming at the mouth; cold, clammy skin; retained urine; disturbed vision; tinnitus; paresis; delirium; convulsions, and coma. Three drams have caused death. Stimulants, warmth to the extremities, and hot and cold douches are specially indicated. A large proportion of C0 2 in the respired air causes giddi- ness, ringing in the ears, irritation of the throat, loss of mus- cular power, feeble pulse and breathing, and coma. The pure gas terminates life instantly by apnea (asphyxia) from spasm of the glottis. C0 2 is classified as a negative narcotic, suffoca- tive poison. The main point in the management of these cases is removal of the patient into the fresh air and the use of arti- ficial respiration if the symptoms demand. Carbon monoxid (coal-gas, water-gas) is a deadly narcotic poison, driving out oxygen and combining with the hemoglobin of the blood, which in extreme cases becomes of a markedly bright-red appearance. Small quantities or the gas produce headache, vertigo, muscular weakness, and nausea. A fatal termination is preceded by asphyxia, local paralyses, subnormal temperature, convulsions, and unconsciousness. The treatment is not often successful, and includes removal into the fresh air and slapping the chest with wet towels, or resort to artificial respiration. Transfusion of blood from another person should improve the chance of recovery. CO is the active agent in the so-called charcoal poisoning practiced by suicides in France. One per cent, in the atmosphere is dangerous. Sewer-gas is a narcotic poison, and more than 1 per cent, in the atmosphere may prove fatal. The symptoms are nausea, vomiting, pains in the abdomen and extremities, vertigo, paresis, convulsions, and insensibility. The best treatment is removal into fresh air and the use of stimulants as needed. Formaldehyd, when freely inhaled or swallowed, produces 354 TOXICOLOGY. mucous congestion, unsteady gait, and sometimes coma. For poisoning by inhalation, ammonia cautiously inhaled is recom- mended. When formalin has been swallowed, the treatment is the same as for acute alcoholic poisoning. DEPRESSANTS. Depressants, or hypostheniants, are marked especially by feeble pulse and breathing, and cause death by paralysis of the heart or respiratory center. Insensibility does not come on until C0 2 narcosis supervenes. All depressants except the cyanogen compounds have as antidotes tannic acid or strong green tea. Hypodermics of strychnin, brandy, aromatic am- monia, ether, digitalin, and atropin, and the administration of strong coffee arid amyl-nitrite inhalations are in order. The recumbent posture should be strictly maintained. Artificial respiration may be required. Mustard poultices to the pericar- dium do good. The patient should be kept warm. Faradization or galvanization of the respiratory muscles is recommended by some authorities. Hydrocyanic acid and substances containing it (cyanids, cherry-laurel, oil of bitter almonds, wild-cherry bark, cassava, pits of stone-fruit, etc.) produce almost immediate salivation; constricted throat; giddiness; falling; insensibility; convul- sions; glassy, protruded eyes; sobbing or stertorous breathing; frothing at the mouth; coldness, and collapse. The acid itself usually kills in fifteen to thirty minutes. Death has followed the ingestion of 30 minims of the official acid, 2 1 / 2 grains of KCN, and 20 minims of oil of bitter almond. The peach- blossom odor of HCN" and cyanids is very characteristic. A watch-glass with a drop of AgN0 3 solution adhering to it, when held before the mouth of the patient may show a white film of AgCN. Whatever is to be done must be done quickly. Empty the stomach immediately; slap the chest with a wet towel; use artificial respiration; inject atropin, strychnin, or ether; and use amyl nitrite or ammonia by inhalation. Chlorin- water and calcium chlorid are mentioned as antidotes. For the cyanids, which are somewhat slower in action, a mixture of ferric and ferrous sulphates with sodium carbonate might be of service. Nitrobenzene (oil, or essence, of mirbane) is like prussic acid in action, but much slower. It is marked by cyanosis, Cheyne-Stokes breathing, and apoplectiform coma. The drug smells like oil of bitter almonds, but does not turn crimson with sulphuric acid. Fifteen grains have been fatal in from four to DEPRESSANTS. 355 twenty-four hours. The treatment is the same as for H(M poisoning. The nicotin of tobacco produces nausea, vomiting, purging, pallor, giddiness, slow pulse, great depression, tremors, cold sweats, contracted pupils, and tetanic or clonic convulsions. There is a strong tobacco-odor about the patient; nicotin itself is colored blood-red or brown by chlorin. One minim of nicotin has proved fatal, the period of death being from five minutes to an hour or more. Lobelia and its preparations give rise to symptoms very similar to those produced by tobacco, but there is more nar- cotism. The peculiar heavy, unpleasant odor of the plant may be noted. One ounce of the leaves has led to a fatal result. The fresh leaves of conium (hemlock) have been mistaken for parsley. It causes gastric irritation; vertigo; diplopia; ptosis; slow, labored breathing; dilated pupils; drowsiness; staggering; motor paralysis; dysphagia; aphonia, and as- phyxia. It has a peculiar odor. The fatal dose of coniin is 1 minim; period, one to three hours. Cocain poisoning is accompanied by a small, rapid, inter- mittent pulse; slow, shallow breathing; a sense of tightness about the chest; dilated pupils; cold, clammy skin; hallucina- tions; delirium; convulsions, and coma. The patient may complain of feeling small foreign bodies under the skin. The drug makes the tongue tingle, then anesthetic. A solution dilates the pupil of a cat or dog when locally applied. Less than a grain of the hydrochlorate has caused death in a few minutes to several hours. Gelsemium preparations produce vertigo; diplopia; ptosis; dysarthria; dilated pupils; labored breathing; rapid, feeble heart; extreme weakness; wide anesthesia; and perhaps tetanic convulsions. A dram of the fluid extract has caused death in from one to eight hours. Morphin is specially indicated. Aconite preparations find frequent use in medicines as fever-cures and neuralgia liniments; the root has been mis- taken for horse-radish. Toxic symptoms are burning and tin- gling of tongue and throat; numbness of finger-tips; cardialgia; weak, slow pulse; nausea and vomiting; coldness; dilated pu- pils; difficult, feeble breathing; and very great prostration. Consciousness is retained to the last. Of the tincture, 25 minims have proved fatal; of the alkaloid, 1 / 12 grain. Death is sudden from collapse or asphyxia within three or four hours generally. Atropin, brandy, coffee, strychnin, and digitalis are most helpful. The back and limbs may be rubbed with hot towels. 356 TOXICOLOGY. Calabar bean, or physostigma, and its alkaloid are distin- guished by the marked myosis they produce. Other symptoms are vertigo; nausea, vomiting; slow, shallow respiration; abol- ished reflexes, and general paralysis. Eserin gives a marked red color with bromin-water. Of this alkaloid, 1 1 / 5 grains have proved fatal. Atropin is the physiologic antagonist. Chloral is of use at an early stage. The arrow-poison, curare or woorara, produces a chill; rapid, weak pulse; sighing, labored breathing; fever; protrud- ing eyeballs; inco-ordination, and motor paralysis. Injected beneath the skin of a frog, it causes paralysis of the voluntary and respiratory muscles. A few grains have caused death in one and one-half hours or more. Alkaline solution of potas- sium permanganate is of service locally. The coal-tar antipyretics frequently lead to cyanosis; slow breathing; feeble, irregular pulse; vomiting; profuse sweat- ing, and profound prostration. Five grains of acetanilid have caused death. Alcohol, ether, strychnin, and oxygen inhalations are the best stimulants in such cases. Warmth should be ap- plied to the feet and the body. The symptoms and treatment of anilin poisoning are similar. Santonin, used so extensively as a vermifuge, has caused death in the dose of 2 grains. The symptoms of poisoning are violet or green-yellow vision, trismus, dilated pupils, hallucina- tions, convulsions, and collapse. The urine is colored greenish yellow; red, if alkaline. CONVULSANTS. These are characterized chiefly by tonic and clonic spasms. The mind is usually clear till near the end. Nux vomica and ignatia contain the alkaloids strychnin and brucin. The former is sometimes used in vermin-killers. It has a very bitter taste, and produces restlessness, shivering, shuddering, epigastric pain, twitching muscles, sudden jerkings of the limbs and head, and especially tonic spasms of the neck, back, chest, and dia- phragm, followed by sweating. The resulting dyspnea is marked by a livid, congested face, which wears an unmeaning smile (risus sardonicus) ; the eyes are staring and the pulse becomes very rapid and feeble. The senses are extremely acute, and the slightest noise or excitement may precipitate a spasm. Although there is a strange feeling in the jaw, this is seldom involved in spasm, and then late (distinction from tetanus). The symp- toms of brucin poisoning are similar, but slower and less marked. One-half grain of strychnin, 30 grains of powdered nux, and 3 grains of brucin have resulted fatally. The period CHRONIC POISONING. 357 of death from strychnine is from five minutes to six hours; average,, two hours. Tannic acid or hot, strong coffee or green tea and charcoal are useful antidotes. Keep the patient quiet in a darkened room; use chloroform or ether inhalations during the paroxysms; also artificial respiration if needed. Chloral in milk by the rectum is a most efficient antagonist. Ice to the spine is of some service. Picrotoxin, or cocculus Indicus, sets up choreic spasms (mostly flexor), giddiness, lethargy, delirium, coma, and slow, labored breathing. It has an intensely bitter taste. Sulphuric acid gives with it an orange-yellow color. Three grains of picro- toxin have caused death in about a half -hour. The treatment is the same as for strychnin. CHRONIC POISONING. Chronic poisoning is generally the result of occupation or environment. The continued absorption of metallic substances leads first to neuritis and later paralysis. The treatment in general is to remove the cause if possible; to get rid of the accumulated poison by the administration of full doses of potas- sium iodid in plenty of water; and the symptomatic relief of paralysis and other symptoms by electricity and other suitable measures as indicated in the individual case. In the treatment of lead poisoning dilute sulphuric acid and magnesium sulphate are administered to ppt. the poison excreted by the intestine and eliminate it in this way. Injections of morphin and atro- pin may be occasionally required to relieve pain. LEAD. Chronic lead poisoning is seen most frequently in painters, printers, plumbers, smelters, and founders; less frequently in potters, file-cutters, leather-cutters, pewterers, lace-makers, artists, tinners, glazers, glass-grinders, and manufacturers of lead paints, glass enamel, hair-brushes, oil-cloths, rubber, shot, sheet-lead, etc. It may arise from drinking-water, especially when this is soft or carbonated; also from drinking acid liquors from pewter vessels or stop-cocks. Other occasional sources are tin-foil goods, chrome-yellow in cakes and candies; acid canned goods; vinegar and preserves kept in glazed earthen vessels; snuff colored with minium or chromate; contamina- tion of flour by plugs of lead in millstones; contamination dur- ing manufacture of acids and salts; leaden toys; colored paper; 358 TOXICOLOGY. false teeth; biting off thread weighted with white lead; use of PbS as a hair-dye, or of carbonate as a cosmetic; the use of shot in cleaning bottles; soda or potash kept in flint-glass bottles; hat-linings glazed with white lead; lead plates in den- tistry; collyria; vaginal injections; sleeping in freshly painted rooms. The leading symptoms of plumbism are motor paresis or paralysis, most marked in the extensor muscles of the forearm ("wrist-drop" or "thumb-drop"), preceded by slight numbness and tremors; neuralgic pains in the flexures of the joints; amaurosis; obstinate constipation, with paroxysms of twisting, grinding pain (lead colic) in the middle abdomen, which is usually depressed and board-like; slow, full, hard pulse; sallow, anemic pallor; and afebrile encephalopathy (mental depression and lassitude, headache, dizziness, disturbed sleep, delirium, hallucinations, saturnine lunacy, epileptiform convulsions, and partial coma). A blue line is sometimes noted at the intragingival margin of the gums and teeth, due to a deposition of PbS in the cap- illaries. If a small area of skin is painted with 6-per-cent. sodium sulphite, it will darken after a few days. The metal is nearly always to be found in the greatly concentrated urine (boil down with dilute nitric acid), especially after the admin- istration of KI for a day or so. ARSENIC. Chronic arsenical poisoning may result from continuous medication or homicidal administration. It also occurs among smelters, miners, furriers, taxidermists, naturalists, manufact- uring chemists, embalmers, and dress-makers (from green tarlatan). Occasional sources of poisoning are from green wall- paper (from less than a grain to a dram per square foot), toys, and candies; anilin-dyed lace and clothing; artificial flowers; carpets; porcelain lamp-shades; and the internal use of the drug for cosmetic effect. The symptoms of arsenism often simulate enterocolitis or even typhoid fever. There is gastro-intestinal irritation, nau- sea, vomiting, and diarrhea; conjunctivitis and edematous puff- ing of the lower lids; squamous or vesicular eruptions; grad- ually increasing diffuse multiple neuritis (numbness and tin- gling of fingers and toes, darting pains in limbs and continuous pain in joints), followed by local (rarely general) pareses and paralyses, chiefly of the leg-extensors and peroneal group, caus- ing "steppage gait." Albuminuria is common, and arsenic may CHRONIC POISONING. 359 be detected in the urine by Marsh's, test after oxidizing all or- ganic matter. Sudden death from heart weakness is observed in habitues. MERCUEY. Hydrargyrism is observed among quicksilver miners, smelters, gilders, hatters, furriers, bronzers, photographers, and manufacturers of barometers, thermometers, amalgams, artificial teeth, and vermilion pigment. It may also arise from fillings in teeth or from medication. The most characteristic symptom of chronic mercurial poisoning is the "intention tremors" (aggravated by motion), followed by paralysis ("shak- ing palsy"), extending gradually from the upper extremities to all the muscles of the body. Another important and early symptom is ptyalism, accompanied by sore and swollen gums and very offensive breath, and rarely followed by falling out of teeth and maxillary necrosis. The poison can be detected in the urine the next day after giving KI. Acidulate urine with HC1, add Cu filings, heat for five minutes at 50 to 60 C., and let stand till cool. Wash filings, transfer to a shallow dish, and invert over this a watch-glass having on its under-surface 1 drop of 1-per-cent. AuCl 3 solution. On heating over a low flame the Hg film on the Cu will volatilize and redden the Au- C1 3 . This test is said to react with 1 part of Hg in 10,000,000. COPPER. Chronic copper or brass poisoning has been noted among artisans who work in these metals. It may also occur from keeping food in dirty copper vessels or from color adulterations. The subjects of this condition complain of an acrid, styptic, coppery taste; of a dry, parched tongue; heat and con- striction of the throat; and continuous spitting. There is sometimes a greenish or purple line at the gum-margins; colicky pains and abdominal tenderness; and bloody, greenish diarrhea, with tenesmus. Greenish perspiration has been ob- served in the hairy parts. The metal can generally be isolated from the urine. ANTIMONY. Chronic antimonial poisoning may be caused by medication or homicidal administration. There is great depression; clammy sweats, distressing nausea, with occasional mucous and bilious 360 TOXICOLOGY. vomiting,, dyspnea, and a small, frequent pulse. The urine is increased in quantity and shows the poison with Marsh's test. SILVER, Argyria rarely occurs nowadays from the protracted ad- ministration of silver salts, and has also been noted in persons engaged in silvering glass. The characteristic sign is a per- manent olive, slaty, or gray-brown coloration, beginning in the conjunctiva, around the nails, and the inside of the lips. It is irremediable, and is due to decomposition of Ag salts in the tissues exposed to light, with deposition of the metal. Promi- nent nervous symptoms are inco-ordination, tetanic convulsions, and wide-spread paralysis, without loss of electromuscular irri- tability. PHOSPHORUS. Chronic phosphorus poisoning is seen among people en- gaged in the manufacture of matches with white phosphorus. The chief lesion is periostitis of the jaw, followed by caries of teeth and necrosis of the bone. Carious teeth predispose. Gastro-enteritis, joint pains, peripheral palsies, jaundice, hectic fever, chronic bronchial catarrh, and peptonuria may be present. Oil of turpentine and alkaline mouth-washes may help to pre- vent necrosis. ALCOHOL. Chronic alcoholism is marked by chronic gastric catarrh, with furred tongue and morning vomiting. Peripheral neuritis and fine tremors of the hands and tongue (worse mornings be- fore a drink) are also noted, as well as a marked moral change. The small veins of the nose and cheek are dilated, and the eyes are red and watery. Delirium tremens is sometimes precipi- tated by trauma or acute fevers, particularly pneumonia. He- patic cirrhosis, granular kidney, fatty heart and liver, and a special liability to phthisis and acute infections are among the effects of the long-continued use of alcohol. TOBACCO. Smoking is more likely to excite toxic symptoms than chewing. Among the most important symptoms of chronic tobacco poisoning are cardiac palpitation and false angina pec- CHRONIC POISONING. 361 toris, rapid or intermittent pulse, granular inflammation of the fauces and pharynx, tremors, giddiness, nervous depression, sclerosis of middle ear, and amaurosis or fluttering scotoma and color-blindness. The dryness of the throat, from the caustic action of the potash in the leaf, favors dyspepsia and alcoholism. MORPHIN OR OPIUM. The morphin or opium habit may be developed even in young infants from sucking an habitue or from the continued use of soothing syrups. The signs of addiction are chiefly progressive asthenia; disturbed sleep; mental depression; moral perversion; haggard countenance; dry, harsh skin (often needle-scarred); deranged appetite and digestion; precordial distress; occasional profuse sweats, preceded by chills and fever; and sexual perversions and impotence. An important point in diagnosis is the marked improvement in the subjective symptoms on giving another dose of the drug. CHLORAL. The chloral habit causes impairment of intellection, will, and memory; silly excitability and volubility; persistent drow- siness (very wakeful without drug); sensory disturbances; anemic, but flushed, face; erythema of skin of fingers, with ul- ceration around nails; feeble, irregular, irritable heart; and polyuria, often stained with bile. This drug may cause de- lirium tremens. COCAIN, A cocain "fiend" is often the result of patent "catarrh cures" or of the attempt to substitute this drug for morphin. Hyperesthesia of the special senses, especially of hearing, is a prominent symptom. There is absolute insomnia or hypnosis, and lewd hallucinations and delusions. The facies is pallid, yellow, and care-worn; the breath very fetid; the skin bathed with perspiration. Hydruria and sometimes incontinence obtain. ERGOT. Chronic ergotism occurs from eating bread containing the fungus of rye and darnel. The affection is sometimes epidemic in Spain and Russia. The prolonged use of the drug medic- inally may also act as a cause. The patient complains of dis- 362 TOXICOLOGY. turbances of special and general sensation; of pain in the back and painful muscular cramps; of chilly sensations and night- sweats. The skin is pale or earthy, and dry gangrene of fingers and toes appears in the gangrenous form. The temperature is subnormal. Epileptoid flexor spasms and sometimes gradual loss of tendon-reflexes may take place. DAMAGED MAIZE. Maidismus, or pellagra, is confined to southern Europe and is nearly always epidemic. It is due to the fungus, Reticularia ustilago. The most marked sign of the disease is a diffuse erythema in the first stage; turning to marked pallor or patches of capillary congestion in the second; and in the third stage the skin becomes dry, shriveled, and dark brown, with exfoliation and suppuration. TEA AND COFFEE. Men and women who drink much tea complain of flushings, insomnia, restlessness, headache, vertigo, tinnitus, flashes of light, mental dullness, and confusion. They are mentally exhausted and apprehensive of evil and disinclined to mental exertion. The heart's action is increased and irregular. Mus- cular tremor, hyperesthesia, and paresthesia are sometimes noted. Chronic coffee intoxication, such as is observed in Brazil, is marked by a state of constant wakefulness and excite- ment and digestive and cardiac disturbances. Coffee addiction is particularly injurious to children, because of its excessive stimulation of the nervous system. IODISM. The administration of iodids in excess leads to running at the nose, sore throat, bronchitis, salivation, gastric irritation, erythematous patches, heavy pain over the frontal sinus, neu- ralgia and tinnitus aurium, and even convulsive movements. Rapid emaciation may occur. BROMISM. Taking bromids for too long a period causes a general low- ering of cutaneous and pharyngeal sensibility, mental depres- sion, dulled intellection, and inability to work with the brain. POISONOUS BITES AND STINGS. 363 The tongue is coated and the digestion disordered. Quite often there is an eruption of red acneiform papules, mostly on the face and back. CYANOGEN. Chronic cyanogen poisoning is observed among photog- raphers and gilders. It is characterized by headache, vertigo, tinnitus, throat constriction, indigestion, constipation, dyspnea, and precordial pain. The face is pale, the pulse full, and the breath offensive. CARBON DISULPHID. Chronic poisoning by this substance is noted in the manu- facturers of rubber goods. There is a stage of excitement, fol- lowed by depression. The symptoms are chiefly nervous, and include headache; irritability; debility; tinnitus; formication; hyperesthesia, followed by anesthesia; insomnia; sometimes monospasm, monoplegia, or paraplegia; and especially pains in the limbs. CHROMIUM. Men who make potassium dichromate are often troubled with obstinate sores on their hands. These sores slough, form- ing a deep, foul ulcer, with hard edges. POISONOUS BITES AND STINGS. The venom that passes from the poison-gland of a dan- gerous reptile through the hollow fang into the wound made by a bite quickly causes the part bitten to become dark, swollen, and very painful. The chief general symptom is prostration; but dyspnea, jaundice, cold sweats, bilious vomiting, delirium, and convulsions may occur. The wound should be promptly drained by incision and cupping or sucking. There is no danger in sucking out snake-venom or even in swallowing it, providing there are no cracks in the mucous membrane about the lips and tongue. The local injection of liquor ammonia and of a strong solution of potassium permanganate or calcium chlorid is rec- ommended by various authorities. An intermittent ligature should be applied above the wound to prevent as much as possible the introduction of the poison into the general cir- culation. Alcoholics, strychnin, atropin, and other stimulants should be administered in full doses, but not ad libitum. Cal- 364 TOXICOLOGY. mette's antivenene, in frequently repeated injections of 10 to 20 c.c., has saved life when used promptly. The poison of venomous reptiles consists essentially of a pepton and a glob- ulin. The bite of a rabid dog is likely to lead in a few weeks to the development of hydrophobia. Thorough excision of the entire wound area is the safest procedure in these cases. Next best is to encourage free bleeding and then to cauterize the wound thoroughly with strong HN0 3 , neutralizing any excess with baking-soda or ammonia. The acid is more penetrating in its action than silver nitrate, commonly used for this pur- pose. The sting of bees and ants, and more especially wasps and hornets, may lead to erysipelatous swelling, suppuration, gan- grene, and even death. The treatment is to remove the poison as much as possible by wet-cupping, then neutralize the acid present in the poison with ammonia or baking-soda. The mere application of one or other of these is usually sufficient in mild cases. QUESTIONS ON TOXICOLOGY. 1. Explain the principle of the ligature in cases of snake-bite. 2. How may a small dose of arsenic prove fatal, while a larger one does not? 3. How distinguish between antemortem and post-mortem imbibi- tion of poisons by the viscera? 4. A body dead for some weeks shows yellow stains in the viscera from arsenic; red from antimony; black from mercury. Explain. 5. Bodies have been exhumed some years after burial and found in a good state of preservation. What poison should be suspected? 6. What is the antidote for concentrated lye? 7. Explain curdy vomit in poisoning by silver or lead salts. 8. In a certain case of poisoning a blue vomit was noticed. Explain. 9. Write equation for the antidotal reaction of ferric hydrate with arsenous oxid. 10. What common syrup may be the source of antimonial poison- ing? 11. Name six common household antidotes and their special uses. 12. What causes the yellow staining of the tissues in nitric-acid poisoning? 13. In a case of poisoning white fumes are produced by dipping a glass rod in HC1 and holding it near the mouth. Explain. 14. Explain antidotal effect of sodium hyposulphite with hypo- chlorites. 15. Why should fats and oils be avoided in poisoning by phenol or phosphorus? 16. What acid chars the tissues and stomach-contents? 17. What gaseous poison accumulates in and around beer- vats? 18. What dangerous poison is sometimes given out from red-hot base-burner stoves? QUESTIONS. 365 19. What possible danger is there from the use of carbonates and bicarbonates as antidotes for mineral acids? 20. How prove the presence of P in match-heads? 21. Name five poisons that may cause fever. 22. Compare the symptoms of opium and belladonna poisoning. 23. Compare the symptoms and treatment of poisoning by corrosive acids and by caustic alkalies. 24. Mention the chief points in the diagnosis of the poison taken gained by looking into the patient's mouth. 25. What effect would a hot-sulphur bath have on a person who has been "leaded"? PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY. CHEMIC COMPOSITION OP THE HUMAN BODY. OF the 21 elements found normally in the human body, 17 are constantly present. C (13 V 2 per cent.), H (9 per cent.), N (2 V2 per cent.), and (72 per cent.) constitute 97 per cent., by weight, of the body, chiefly in combination, though the last three also occur free in the blood, stomach, and intestines, N and being inhaled or swallowed and H arising from putre- factive processes. The following elements are likewise essential body ingre- dients in the percentages mentioned: Ca, 1.3; P, 1.15; S', 1 / 7 of 1 per cent.; Na, 0.1; Cl and F, each, l / ia of 1 per cent.; K, V 40 of 1 per cent.; Mg, 1 / 80 of 1 per cent.; Fe, 0.01 (3 gm. altogether); Si, Vsoo of 1 per cent.; Mn, 0.0005 per cent.; and I, a trace. Na is present chiefly in the fluids of the body, which it renders alkaline, while K occurs, for the most part, in the solid tissues, because membranes absorb it better. S occurs as taurin in the muscles and bile, as H 2 S in the feces, and as sulphates in the urine. Fe is the coloring matter of blood, bile, hair, and skin pigment. It has great affinity for 0, which it carries from the lungs to the tissues. It is present in the liver as the organic compounds ferratin and hepatin. A considerable trace of I is met with in the thyroid. It seems to exert an antitoxic action and to increase the metab- olism of proteins. A deficiency of thyroidin leads to the pecul- iar disease myxedema. Traces of Mn, As, Cu, Pb, Al, and Br are occasionally encountered in the liver, which acts as a buffer for the rest of the system, protecting it from poisoning from without and from within. Of the inorganic compounds that help to make up the body, H 2 is most abundant, constituting 67.6 per cent., by weight, of the whole, and ranging from 0.4 per cent, in the enamel of teeth to 99.5 per cent, in saliva. Water is the sys- tem solvent for absorption, secretion, and excretion. It makes the tissues soft, flexible, and elastic, and by evaporation aids in (366) CHEMIC COMPOSITION OF BODY. 367 regulating animal heat. About a pound of H 2 is formed daily in the body by the oxidation of H compounds. A loss of 5 or 6 per cent, of water, as in cholera, renders the blood viscid and slow of current, irritating to the nerves, and causing con- vulsions. The nascent H produced by cell-decomposition probably unites first with 0, forming H 2 2 ; and this has been found in the sweat and other fluids. The peroxid thus formed quickly breaks down into H 2 and nascent 0. Of compound gases, C0 2 , H 2 S, and CH 4 are most impor- tant. The first is formed in living cells by internal oxidation, and also during fermentation in the alimentary tract. It is present chiefly in the blood in combination with Na. H 2 S, formed by the putrefaction of S-containing proteins (eggs), occurs mostly in the bowels, but may also be found in old abscess-cavities. CH 4 is derived from acetates, the fermenta- tion of cellulose, or protein putrefaction, and is the principal gas giving rise to flatulence and colic. It is the only hydro- carbon found in the body. The chlorid of Na is present in all the body-fluids (0.65 per cent, in blood-serum), and is of great importance in pro- moting osmosis and diffusion. KC1 is most abundant in blood- corpuscles and muscles. CaCl 2 is also a necessary ingredient of the blood. The chlorids generally pass through the body unchanged, except the small proportion of NaCl used up in making HC1. CaF 2 is present chiefly in the bones and teeth, especially the enamel (2 per cent.). The phosphates of K, Na, Ca, and Mg are present in nearly every tissue and fluid of the body, in loose combination with proteid compounds. The alkalinity of the blood is due partly to the secondary sodium phosphate, Na 2 HP0 4 , which is partly changed by C0 2 to the primary phosphate, NaH 2 P0 4 , to which the acidity of the urine is largely due. Fe 2 (P0 4 ) 2 is present in the bile, the gastric and intestinal juices, and in the pigment of hair and epithelium. The carbonate of Ca is an essential component of bones and teeth. The otoliths of the internal ear are composed of crystalline CaC0 3 . The carbonates of K and N"a aid in ren- dering the blood alkaline. They take up C0 2 , forming bicar- bonates. Ammonium carbonate is found normally only in traces in the blood. The amount is greatly increased in cholera, with ammoniacal breath and stools. A small quantity of the sulphates of K, Na, and Ca is found in nearly every part of the organism. Very minute quan- tities of Si0 2 are obtained from the blood, urine, bones, and 368 PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY. hair. NH 3 is produced in the tissues "by the union of N and H. It combines with C0 2 to form ammonium carbamate, which is dehydrated in the liver into urea. The non-nitrogenous organic constituents of the body in- clude CH 4 , dextrose, lactose (breast-milk), inosit, glycogen, fats,, and fatty acids. Dextrose is the chief sugar of the blood and muscles. There is at least 0.1 in the blood, even during starvation. It is derived mainly from starch and cane-sugar, but is also in part a derivative of proteins, which may be made to yield arti- ficially as much as 60 per cent, of dextrose. Inosit [C 6 H 6 (HO) 6 ] is present in muscles and viscera. It can be oxidized and utilized by diabetics. Lactose is a leading ingredient of mothers' milk (and amniotic fluid), and is likely to be found in the blood and urine whenever the milk-flow is obstructed. The glucosid, jecorin, found in the liver and the blood, yields dextrose on decomposition. Indican is a brownish, bitter, syrupy glucosid derived from indol, a weak base produced by the pancreas and during intestinal putrefaction. The body-glycogen is about equally distributed in the mus- cles (0.4 to 0.8 per cent.) and the liver. This supply is drawn upon by hunger. Muscular work also causes a rapid conversion of glycogen into dextrose. The glycogen is probably derived in part from tissue-proteins. The body-fat is all in a fluid condition, owing to the con- siderable proportion (67 to 80 per cent.) of olein with the palmitin and stearin. Lecithin is a waxy, phosphorized fat present in every living cell, and most abundant in the brain and nerves. Boiling with acids or alkalies breaks it up into cholin, fatty acids, and glycerophosphoric acid. It swells in distilled water, giving rise to the "myelin forms" of nerve-tissue. Protagon is obtained from the brain. It is a crystalline body containing lecithin and cerebrin. The latter is a glucosid, breaking up into d. galactose. Organic acids are present chiefly in the excretions (often as under-oxidation products) and in fermentation and putre- faction compounds. HCOOH is found in sweat. The formates are much increased in the blood and urine in fever, diabetes,, leukemia, and wood-alcohol poisoning. CH 3 COOH is often found in feces. When absorbed from the intestine it is burned into C0 2 and H 2 0. It is present in the blood, sweat, and urine in leukemia and diabetes. Diacetic acid (CH 2 CH 3 COCOOH) and beta-oxybutyric acid (CH 3 .CHOH.CH 2 COOH) probably result from fat-metabolism. They are increased in starvation and diabetes, neutralizing the blood and causing coma and increase- CHEMIC COMPOSITION OF BODY. 369 of NH 3 in the urine. (CH 3 ) 2 CO is increased in the blood and urine whenever there is excessive decomposition of fat, as in diabetes. C 2 H 5 COOH, from protein putrefaction, is found in the sweat, bile, and sometimes in the stomach. C 3 H 7 COOH, from the putrefaction of proteins and carbohydrates, is found in the stomach-contents in hypochlorhydria, and in the intes- tinal evacuations. A bad taste in the mouth is frequently due to this acid. H 2 C 2 4 is a metabolic product derived chiefly from nucleins and gelatins. The foul-smelling isovaleric acid, C 4 H 9 COOH, from pro- teid decomposition, is noted in sweating feet and sometimes in the urine in certain grave diseases. Capric and caprylic acids are found in the perspiration and in milk-fat; palmitic, oleic, and stearic acids are present in milk-fat and adipose tissue. The very slight acid reaction of bile is due to these three acids. C 3 H 6 3 , from fermented milk, is of common occurrence in the stools of infants. Sarcolactic (paralactic, or right ethidene) is found in the muscles, blood, and blood-glands, and is derived from protein tissues. It causes the formation of KH 2 P0 4 , with the coagulation of myosinogen, during rigor mortis. The essential nitrogenous compounds of the human body are mostly globulins, serum-albumin being the main exception. Phenol, indol (C 8 H T ]S T ), and skatol (C 8 H 8 CH 8 NH) are formed by putrefaction of proteins in the intestines and, with H 2 S, give the ordinary fecal odor to the stools. Leucin (C 5 H 10 NH 2 - COOH) and tyrosin are normal products of tryptic digestion of hemipeptons. Like other amido-acids, they are oxidized in the liver into urea, with production of heat; when the liver is diseased (acute yellow atrophy, P poisoning) they appear in the urine. Urea [(NH 2 ) 2 CO] is the chief end-product of nitrogenous metabolism in mammals, and is formed, perhaps, in all tissues where proteid decomposition takes place. Its principal site of origin is the liver, where it is formed by dehydration of ammo- nium carbamate, which is produced in the tissues by the union of C0 2 and NH 3 . The amount of urea normally ranges from 0.008 to 0.016 per cent, in the blood, muscles, and viscera; 0.067 per cent, in the kidney. When the kidney fails to functionate (uremia) these relative proportions may be nearly reversed. Creatin, or methyl-guanidin acetic acid (HNCNH 2 NCH 3 - CH 2 COOH), is a product of proteid decomposition, especially of the muscles (0.3 per cent.). It is excreted in the urine as creatinin: creatin less water. The purin, or alloxuric, bodies contain both the radical (N 2 C) of urea and that (N 2 C 4 ) of alloxan: 370 PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY. /NH-CO\ '\NH-CO/ ]Jypoxanthin, or sarcin = C 5 H 4 N 4 0; xanthin = C 5 H 4 - N 4 2 ; uric acid = G 5 H 4 N 4 3 ; purin = C 5 H 4 N 4 ; adenin = C 5 H 5 N 5 ; guanin = C 5 H 5 N 5 0. Nucleins cleave into a protein and nucleic acid, and the latter into phosphoric acid and allox- uric bodies, uric acid being a higher oxidation product than xanthin or hypoxanthin. Through oxidation and hydrolysis uric acid can be decomposed into two molecules of urea and one molecule of oxalic acid, and when administered to a mammal it is changed by the liver into urea. Heteroxanthin is methyl- xanthin; theobromin of cocoa is dimethyl-xanthin and isomeric with paraxanthin; caffein is trimethyl-xanthin. The alloxur bodies are normally present in the fluids and tissues of the body and in urine. The normal daily amount of uric acid ex- creted in the urine is from 0.4 to 0.8 gm.; of purin bases, 0.1325 gm. (quadrupled in leukemia). The quantity of uric acid and other alloxur bodies is increased by the ingestion of tea, coffee, cocoa, and nuclein-containing foods, such as young flesh and meat extracts. Eeduced alkalinity of the blood, as in winter from eating meats freely, throws uric acid out of solution, to collect in the more acid tissues (spleen, liver, and joints). With the vernal tide of alkalinity (due to freer sweating, with excretion of fatty acids) these deposits are swept out in the blood-current, irritating the nerves and giving rise to "that tired feeling." Experiment. Prove futility of lithium compounds in uric-acid con- ditions by treating solution of Na 2 HP0 4 (same salt in blood) with a little Li 3 C 6 H 5 O 7 solution. Warm slightly and note white ppt. of Li 2 HP0 4 . Cholin and neurin are amins of olefins produced in the intestines from proteins by the action of bacteria. Glycocoll, CH 2 NH 2 COOH, is a normal decomposition product from pro- teins, and is easily manufactured from gelatin. It exists in the bile as glycocholic acid, and in the urine with benzoic acid as hippuric acid (formed in kidneys) after taking benzoic acid or its derivatives. Taurin (NH 2 C 2 H 4 S0 3 H) is found in the spleen, muscles, suprarenal capsule, and in bile as sodium taurocholate. Fellic acid (C 23 H 38 4 ), cholic acid (C 24 H 40 5 ), and choleic acid (C 24 - H 40 2 ) are probably derived from the non-nitrogenous moiety of proteids. By synthesis with taurin and glycocoll in the liver they form taurocholic and glycocholic (C 26 H 43 ]Sr0 6 ) acids, the salts of which are known as the bile-salts and have the function BONES. 371 of dissolving the more insoluble fatty acids and soaps produced by steapsin. The two bile-acids always occur as Na salts in bile and are probably oxidation products of proteins. These conjugated acids give rise on decomposition to cholalic or other allied acid and an amido-acid (amido-acetic = glycocoll, or amido-ethyl- sulphonic = taurin). Cholalic acid oxidizes into one ketone and two aldehyd groups, which have a reducing power on hemo- globin; hence the injurious effect upon the corpuscles of cho- lemia, Cholesterin (C 27 H 45 OH) is probably an accumulation prod- uct of the hydrolysis of carbohydrates. When more is made than can be utilized, it constitutes waste-material and forms gall-stones. Bilirubin (C 16 H 18 N 2 3 ) is the ordinary coloring matter of human bile. Various oxidation products are biliverdin (green), bilicyanin (blue), and bilixanthin (brown-yellow). The final products of body decomposition after death are such simple substances as C0 2 , H 2 0, NH 3 , H 2 S, and mineral chlorids, sulphates, and phosphates. There are a large number of intermediate products, the most important being the cadav- eric alkaloids or ptomains. The soap-like conversion into adi- pocere, which dead bodies sometimes undergo, is due to the formation of Ca salts of palmitic and stearic acids, through the agency of bacteria. The moving cells and the fixed tissues of the body are com- posed of protoplasm: that is, of proteids with such a molecular arrangement as admits of the phenomena of life. BONES. Adult bone contains 69 per cent, of earthy matter, of which Ca 3 (P0 4 ) 2 constitutes 59 per cent. (.3 molecules to 1 of carbonate); CaC0 3 , 7 per cent.; Mg 3 (P0 4 ) 2 , 1.3 per cent.; and CaF 2 and soluble salts, 1.5 per cent. The bones of infants and young children contain much less mineral matter; hence are less brittle. The compact portions of bone contain more min- eral matter than the cancellous. Undried bone is about half water. The animal matter of bones, termed ossein (12 per cent, of undried bone: a mixture of collagen and elastin) is closely combined with the inorganic salts, so that the shape and size of a bone are retained after these salts have been removed with acids. There is also 15 per cent, of fat, chiefly in the marrow. 372 PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY. Experiment. Place a rather long and narrow bone in 10-per-cent. HN0 3 . Remove the bone in a day or two and tie it in a knot. Experiment. Prove presence of phosphates in acid solution with (NH 4 ) 2 Mo0 4 . Experiment. Test another portion of same solution for Ca and Mg as follows : First treat with Fe 2 Cl 6 , added little by little, testing after each addition with NH 4 HO until this gives a ppt. which is no longer white, but yellowish; then add Na 2 C0 3 until nearly neutral; and finally ppt. the ferric phosphate with 1 or 2 gm. of BaCO 3 ; warm and filter, and ppt. Ba from hot filtrate with dilute H 2 S0 4 . Test the second filtrate for Ca by rendering alkaline with NH 4 OH and adding excess of (NH 4 ) 2 C 2 4 . Test the third filtrate for Mg with Na 2 HPO 4 . Experiment. Heat some fragments of bone in a dry test-tube; note that H 2 O and NH 3 are evolved, and then bone-oil and inflammable gases, leaving bone-black and bone-ash. Take up a little of the black mass on a Pt loop, burn away C, and test for carbonate with an acid. In old age the bones become more porous; hence more fragile. In most bone diseases (rickets, osteomalacia, and osteo- porosis) the lime-salts are diminished, while the organic con- stituents undergo qualitative changes. The phosphates are permanently reduced in the urine after castration of man or woman, thereby benefiting osteomalacia. TEETH. The composition of teeth is much like that of bone, dentine containing 28 parts of animal matter and 72 parts of mineral, with 5 or 6 per cent, of water. Cement, or crusta petrosa, is true bone. Enamel is the hardest tissue in the body, containing only 3 */2 P er cent, of organic matter, and composed chiefly (90 per cent.) of calcium phosphate and fluorid. The enamel of young infants contains from 77 to 84 per cent, of mineral matter. Experiment. Estimate the water in a freshly extracted tooth: Weigh out a gram of the crushed tooth in a tared porcelain crucible, and place in the air-bath at 95 for an hour. Remove, cool, and weigh, and return to the oven for another half-hour; then cool and weigh again. If the last two weights correspond, the tooth is dehydrated; otherwise it should be again heated until the weight is constant. Experiment to Estimate Organic and Inorganic Matter. Place the dehydrated product of the preceding experiment on a triangle, cover the crucible, and burn the organic matter; then remove, cover, and calcine at a red heat till the ash is nearly white. Cool and weigh. Experiment. Place a tooth in 10-per-cent. HNO 3 for two or three days. Then pour off the acid mineral solution and test it for phosphates with (NH 4 ) 2 MoO 4 ; and boil the organic residue with water, forming a gelatin-jelly on cooling. Acid substances, Hg, As, alum, and H 2 2 are especially injurious to the teeth. Liquid medicines containing acids, like MUSCLE. 373 tincture of iron, should be taken well diluted through a glass tube. Eating much candy injures the teeth by reason of the lactic acid produced by fermentation. The common brown variety of dental caries is said to be due to nascent HC1; the white or rapid variety to ETN~0 3 , formed by combination of NH 3 and nascent evolved during fermentation; the black variety may be caused by H 2 S0 4 , formed by the nascent and H 2 S of putrefaction. Acids act more readily on dentine than enamel; hence the tendency of a cavity to enlarge centrally. These acids are formed by the action on foods of various fungi and bacteria. Local inflam- mations, mental strain, pregnancy, and lactation predispose to caries. The tartar of teeth is a gray, brown, or yellow deposit from alkaline saliva, and consists chiefly of Ca 3 (P0 4 ) 2 , with a little CaC0 3 and more or less organic matter, molds and bacteria, silica, and alkaline salts. The salivary secretions hold lime- salts in solution by the aid of C0 2 . On passing into the mouth this is neutralized by NU 3 and other alkalies of putrefactive origin, and the lime salts are precipitated as tartar. MUSCLE. Muscular tissue is made up mostly of collagen and myo- sinogen. Muscle-plasma contains myoalbumin, myoglobulin, myoalbumose, hemoglobin, myohematin, pepsin, rnyosin fer- ment, and amylolytic ferments; sarcolactic, formic, and acetic acids; glycogen, maltose, glucose, and inosit; various salts, especially the phosphates of Mg, Ca, and K and KC1; and the extractives, as urea, creatin, guanin, xanthin, hypoxanthin, and uric acid. These occur free and in nucleins. The sarcolemma is composed of an albuminoid resembling elastin. C0 2 is the principal gas present in muscles. Half the proteid of the body and half the water are in the muscles. The reaction of resting muscle is alkaline; during con- tractions it becomes acid, from sarcolactic acid evolved by the breaking down of proteids. Muscle is three-fourths water, and its density is about 1.055: nearly that of the blood. Rigor mortis is due to coagulation of myosinogen and para- myosinogen by fibrin ferment, forming a clot of myosin. Sar- colactic acid and acid potassium phosphate are also generated in considerable quantity after death, and probably aid in the process of coagulation. Muscular fatigue has been ascribed to the irritating effects on the nerve-plates of an excess of sarco- lactic acid and extractives. 374 PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY. NERVE-SUBSTANCE. The composition of brain and nerves differs from that of other organs in containing a large proportion of phosphorized fatty compounds, such as cerebrin, protagon, lecithin, and choles- terin; the white substance is more fatty than the gray. It is claimed that the anesthetic effect of ether and chloroform is due to their solvent action upon the fat of the neurons. KC1 and the phosphates are the chief salts. The neurolemma con- sists mainly of neurokeratin. The amount of water normally in the brain is from 71 to 83 per cent.; in the nerves, 72 per cent. The chief decomposition products are neurin, cholin, fatty acids, glycerophosphoric acid, and the purin bodies. These products are found in excess in the blood in organic nervous dis- eases. EPIDERMAL STRUCTURES. Epithelia, nails, and hair are composed chiefly of keratins. Human hair contains 4 or 5 per cent, of S. Experiment. Boil some hairs or nail-parings with a little KHO. Then add HC1 and note odor of H 2 S. The nails contain considerable K 3 P0 4 . The granular pig- ment melanin is present in hair, the rete mucosum, and the pigment-layers of the retina, choroid, and iris. It is derived from blood-pigment. Melanotic tumors contain a considerable amount of this pigment. The loss of pigment makes hair gray, and its absence from the iris is noticed in albinos. The en- trance of air into the shafts of hair, as in grief or fright, turns the hair white, but the color may sometimes be restored by driving out the air with hot water. The dermatitis that follows contact with the poison-ivy and other plants of the rhus group is attributed to irritation by the volatile principle, toxicodendric acid; hence the efficacy of alkaline baths. CONNECTIVE TISSUES. White, fibrous tissue consists of collagen; elastic tissue, of elastin. The cement substance is a form of muciri. Fetal fibers yield mucin in place of gelatin after being boiled with water. THE BLOOD. 375 CARTILAGE. The matrix, capsules, and cancellous substance are com- posed of collagen or chondrin; the cells, of a globulin. Cor- neal tissue also yields a chondrin on boiling. Chondrigen itself, the organic basis of cartilage, is a mixture of collagen; an elastin-like substance; chondromucoid; and chondroitic acid, THE VISCERA. These consist, on the average, of about three-fourths water, and are alkaline in reaction, but become acid after death. Pig- ment accumulates in the liver in malaria, from the destruction of red corpuscles. The spleen-pulp contains considerable com- bined iron. The thyroid gland is distinguished for its thy- roidin and glairy, colloid secretion. Calcareous concretions have been found in all the viscera, and especially in pulmonary tubercles. Visceral degenerations include fatty, amyloid, mucoid, col- loid, calcareous, and pigmentary. The change to fat occurs when oxidation of proteids is deficient, as in P, As, and Sb poisoning; alcoholism; and yellow atrophy. Amyloid is a pale, waxy, pathologic protein formed in the course of chronic wast- ing diseases. Mucoid degeneration is manifested by excess of mucin. Vitreous colloid has the formula C 16 H 15 N0 6 ; it con- sists of ISTaCl and colloidin, which is colored red by Millon's reagent. The melanin of pigmentary degeneration (Addison's disease, melanotic cancer) is identic with normal melanin, and is probably derived from hemoglobin. In atheroma of the blood-vessels the yellow spots show fatty and calcareous degen- eration. THE BLOOD. This vital fluid constitutes about V 20 part, by weight, of the human body. It is 795 parts water per 1000, and has nor- mally a sp. gr. of 1.055 to 1.062; higher in men than in women, and reduced proportionately with hemoglobin reduction. Experiment. Determine sp. gr. of blood by making a mixture of benzol with chloroform in such proportions as to be somewhat lighter than blood. Let a drop of blood from the end of the finger fall into the liquid, and when it has sunk add chloroform drop by drop, with stirring, until the drop of blood floats midway in the liquid. Then filter out the blood and find sp. gr. of mixture with hydrometer. Blood is saline because of alkaline chlorids, which keep 376 PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY. the globulins in solution, prevent disintegration of the cor- puscles, and aid osmosis. The alkalinity necessary for proper oxidation is maintained by Na 2 HP0 4 and especially Na 2 C0 3 , which is associated with serum-albumin, the combination being dissociated by C0 2 with formation of NaHC0 3 . Experiment. Prove alkalinity of blood by placing a drop of red litmus solution on a porous porcelain plate. When dry leave a drop of blood on the spot for a minute, then wash off with water. The alkalinity of the blood can be estimated by mixing 5 c.c. of fresh blood with 45 or 50 c.c. of 0.25 per cent. (NH 4 ) 2 - C 2 4 solution (prevents coagulation), titrating the mixture with N / 25 H 2 C 4 H 4 6 solution, using as an indicator lacmoid paper soaked in concentrated MgS0 4 solution. The normal alkalinity is decreased by the production of sulphuric, phosphoric, and the volatile fatty acids in the rapid protein catabolism of fevers, cancer, and diabetes. The opacity of blood is due to the suspended blood-corpus- cles, the red variety of which gives color mainly to the blood, though serum also contains a coloring matter termed lutein. Experiment. Gently shake some fresh blood (diluted 1 to 5) in a test-tube with ether. The cells are dissolved, and the liquid becomes transparent or laky. The number of leucocytes is increased (leucocytosis) in leukemia and in most inflammations, particularly when ending in suppuration. The erythrocytes are diminished in anemias (with proportionate oligochromemia in simple secondary in excess of oligochromemia in pernicious). In chlorosis there is great hemoglobin reduction with but slight lessening of cor- puscles. Hydremia is particularly noticeable after hemorrhages, and is accompanied by absolute hypalbuminosis. Increase of fibrin (hyperinosis) has been noted in pneumonia, erysipelas, and acute rheumatism. The opposite condition, hypinosis, is said to occur in malaria, pyemia, and pernicious anemia. In general, the percentage of proteids varies inversely with the amount of water in the blood. The sugar in the blood is increased up to 9 per mille in diabetes, and is also considerably increased in carcinoma. It may be estimated in the usual way after removing the proteins by boiling with Na 2 S0 4 . Acetone is found in the blood in fevers and diabetes. The glycogen reaction is pronounced in diabetes and leukemia. To test for glycogen a drop of blood is spread between cover-slips and allowed to dry, then treated with a solution containing 1 gm. I and 3 gm. KI in 100 gm. THE BLOOD. 377 of concentrated mucilage. The glycogen appears as brown granules free or in the leucocytes. Cellulose has been found in the blood in tuberculosis. The composition of the blood may be represented some- what graphically by the following outline: Plasma (60 per cent. or less ) Blood Serum Gases 1 Corpuscles ( 40 per cent or more) Water (90 per cent.). Serum-albumin (4.5 per cent.). Serum-globulin (3.1 per cent.). Dextrose (0.1 to 0.15 per cent. ). Salts = NaCl (0.65 percent. ), CaCl 2 , KC1, phosphates, sulphates, carbonates. Fat (0.1 to 1.2 per cent.). Ferments : diastatic, glycolytic, steato- lytic. Extractives = urea (0.016 per cent. ), uric acid, creatin, sarcolactic acid, etc. O = 20 volumes per cent, in ar- terial, 12 per cent in venous. CO 2 = 39 volumes per cent, in arterial, 46 per cent, in ve- nous. N = 1 or 2 volumes per cent, in arterial and venous. Fibrinogen (0.5 per cent.). Stroma. Hemoglobin (about 90 per cent, of dry corpuscle). Lecithin. Cholesterin. Salts = KC1 and K 2 HPO 4 . Nucleo-histon. Lecithin. Cholesterin. Fatty granules. Albumose. K,HPO 4 . ^ Blood-plates = nuclein. White (1 to 350 of red) An increase of fat (lipemia) is noted after the ingestion of large amounts of fatty foods and in obesity, chronic alcoholism, hepatic disease, and after injury to the long bones. Lipacidemia has been observed in fevers, leukemia, and diabetes. Cholemia is met with in cases of obstinate jaundice, ex- cessive secretion of bile, and destruction of red blood-corpus- cles. Other pathologic extractives occasionally encountered are xanthin, hypoxanthin, paraxanthin, guanin, adenin, leucin, tyrosin, lactic acid, and beta-oxybutyric acid. The coagulation of blood is believed to be due first to the union of Ca salts (CaCl 2 especially) with the zymogen pro- 378 PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY. thrombin (from leucocytes of shed blood), forming fibrin-fer- ment. This, in turn, combines with fibrinogen to form a net- work of fibrin-threads, which enmesh and contract upon the corpuscles, making the clot and setting free the serum. The so-called buffy coat is made up of leucocytes. Freshly drawn blood is readily defibrinated by whipping quickly with a stick or a fork. The elastic strings of fibrin thus collected when thoroughly washed resemble boiled white of egg. For the tests given below defibrinated blood should be employed. To separate blood-serum from the clot the blood should be received in a rather wide vessel, and as soon as it clots be placed in an ice-chest for thirty-six to forty-eight hours or longer, until the serum is clear and straw-colored. The cor- puscles can be pptd. from defibrinated blood by adding a 1 / 10 saturated aqueous solution of NaCl to y io its volume of the blood, pouring the mixture into a shallow dish, and after set- tling decanting. The most important constituent of the blood is the color- ing matter hemoglobin, which constitutes over 90 per cent, of the organic matter of the red corpuscles, and in the dry state contains 0.42 per cent, of Fe. It carries (molecule for mole- cule) from the lungs to the tissues, in a loose combination known as oxyhemoglobin. Hemoglobin, or reduced hemo- globin, is the coloring matter of venous blood, and oxyhemo- globin that of arterial blood. Hemoglobin crystallizes with difficulty in purple crystals; oxyhemoglobin more readily in long, bright-reddish prisms. H 2 and some other reagents remove the coloring matter from the corpuscles and thus render blood darker, whereas salt solutions have the opposite effect. On long exposure to air oxyhemoglobin stains isomerize into the more stable brown acid methemoglobin, which is found also at times in cystic fluids and transudations. Oxidizing agents, such as H 2 2 , likewise convert oxyhemoglobin into methemoglobin. The latter crystallizes in red-brown needles or plates, and yields a brown, aqueous solution, turning red on rendering alkaline. On heating with acids or alkalies oxyhemoglobin decom- poses into globulin and the Fe pigment hematin; reduced hemo- globin into hemochrom and a globulin. Hematin is dark brown or blue-black, and amorphous. The dark color of "coffee- ground" vomit in gastric cancer is due to hematin, formed by the action of HC1 on blood. Hematin combines with nascent HC1 to form hematin hydrochlorate, or hemin: a crystalline substance of vital importance in the identification of blood- stains. THE BLOOD. 379 Experiment to Identify a Blood-stain on a Piece of Cloth or Wood. Add to a few of the fibers or scrapings on a glass slide a drop of 1-per-cent. NaCl solution, and warm very gently till nearly dry. Then add at once a drop or two of glacial acetic acid, put on a cover-glass, and warm again gently till nearly dry. Allow to cool and examine under microscope for small, dark-red, rhombic, hemin crystals. These Teich- mann crystals are insoluble in water, but dissolve in alkalies, with for- mation of hematin. Hematoporphyrin is an iron-free derivative of hematin, prepared by the action of strong acids, and isomeric with bili- rubin. It is wine-red in color, and may be noted in the gastro- intestinal contents after mineral-acid poisoning. Experiment. To 10 c.c. of H 2 S0 4 in a test-tube add 4 or 5 drops of blood, shaking thoroughly with each addition. Note the color of hema- toporphyrin. Fig. 47. Hemin Crystals. Hematoidin is a hemoglobin derivative similar to, if not identic with, bilirubin. It appears in orange- or ruby- colored, amorphous particles in old extravasations and in the sputum, urine, and feces after hemorrhages. CO hemoglobin is a compound similar to oxyhemoglobin, but is more stable; hence the grave character of CO poisoning, since cannot displace CO and be carried to the tissues. Experiment. Pass a current of illuminating gas for a few minutes through some diluted blood (1 to 50). Note change of color to cherry red. Prove that CO hemoglobin is a stronger combination than oxy- hemoglobin by treating dilute solutions of each with twice as much strong NaHO solution (pure blood becomes brownish, with a green tinge) ; with H 2 S (pure blood turns green) ; and with a drop each of dilute HC 2 H 3 O2 and K 4 FeCy 8 solution (brownish ppt. with pure blood), in all of which tests the CO hemoglobin solution remains unchanged in color. 380 PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY. The spectroscope furnishes the most delicate evidence of the presence of blood in solution, readily showing 1 part in 10,000. Spectroscopic Tests. Dilute defibrinated blood with 50 parts of water, and suspend some of the fluid in a narrow test-tube about an inch before the slit of the instrument, with a fish-tail burner two inches farther away. 1. Compare the position of the oxyhemoglobin with that of the Na lines. 2. Reduce the oxyhemoglobin by adding a drop or two of Stokes's solution (2 FeSO 4 and 3 H 2 C 4 H 4 O 6 dissolved in H 2 and ren- dered alkaline with NH 4 HO), and note position of single band. Shaking restores the two characteristic oxyhemoglobin bands. 3. To the reduced hemoglobin add a few drops of strong NaHO solution, forming hemo- chromogen, and compare two bands with those of oxyhemoglobin. 4. Tests can be made with less dilute blood (1 to 15 or 1 to 20) for the spectra of methemoglobin (warm dilute blood with a few crystals of KC10J, alkaline hematin (heat blood with NaHO till color becomes a greenish brown), CO hemoglobin (blood diluted 1 to 50), and hemato- porphyrin. It is possible that hemoglobin, like chlorophyl, acts as a dehydrating agent, forming glycogen from glucose. Blood leaving a resting gland is dark and venous; that from an active gland is brighter, owing to C0 2 being given off in the secretion. Plumage pigments consist of lipochromoids and melanoids closely related to the pigments of fishes and reptiles. The blood of most insects is green (from chlorophyl) and darkens on exposure to the air. SECRETIONS. These are the special products of particular glands. They are mostly liquid or semiliquid, and are composed of water, inorganic salts, and organic compounds. True secretions are formed from the blood, but do not pre-exist in the blood, and are of service to the organism. As the blood is alkaline, so all the secretions (except gastric juice and bile) are alkaline and of lower sp. gr. than the blood. Psychic emotions affect both the quantity and quality of secretions, and they are gen- erally diminished in fevers. The digestive fluids constitute the most important class of secretions. They all have a somewhat similar composition (phosphates, chlorids, carbonates, sulphates of Na, K, Ca, and Mg) except in regard to the ferments which they contain. These exist in the glands as zymogens, needing to combine with dilute acids or alkalies to form the full enzyme. The following table shows the chief points in the chemistry of these secre- tions: B C PLATE IV D Eb ABSORPTION-SPECTRA. (Rockwood.) Oxyhemoglobin. Hemoglobin. CO hemoglobin and CO hemochromogen. Methemoglobin, alkaline. Hematoporphyrin, acid. 6. Hematoporphyrin, alkaline. 7. Hemochromogen, alkaline. 8. Hematin, acid. Q. Hematin, alkaline. 10. Sulphur methemoglobin. 11. Methemoglobin, neutral or faintly acid. 12. Pettenkofer's test for biliary acids. SECRETIONS. 381 SECRETION. AVERAGE DAILY QUANTITY. SPECIFIC GRAVITY. FERMENTS. OTHER CONSTITUENTS. Saliva. 800 to 1500 c.c. 1.004 to 1.008 Ptyalin (0.1 per cent.), amylolytic (on boiled starch). Mucin (1.4 per cent.). Potassium sulphocyanate (0.1 per cent.). Epithelia and salivary cor- puscles. Inorganic salts (2 p. m.) = chjorids, carbonates, ni- trites, sulphates, phos- phates of Na, K, Ca, and Mg. Gastric juice. 5000 to 10,000 c.c. 1.002 to 1.003 Pepsin (1.75 per cent.), proteolytic. Hydrochloric acid (free, 0.2 per cent.). Rennin, milk-curd li n g ferment. Organic acids = lactic, ace- tic, butyric. A glycolytic ferment. Acid phosphates (0.02 per cent. ) of Mg, Ca, and Fe. Pseudopepsin. Alkaline chlorids (0.2 per cent.). Pancreatic juice. 200 c.c. 1.010 to 1.015 Trypsin, proteolytic. Sodium carbonate (0.3 per cent.). Amylopsin, amylolytic. Fats and soap. Steapsin, fat-cleaving. Albumin. Rennin, milk-curdling. Leucin and tyrosin. Bile. 500 to 800c.c. 1.020 Pialyn, fat-cleaving. Bile-salts (7.5 per cent.) and pigments. Fat (0.9 per cent. ) and soap. Cholesterin (0.25 per cent.), lecithin, and urea. Mucus and albumin. Sodium carbonate (0.25 to 0.5 per cent.). Salts of Ca, Mg, Fe, and Cu. Intestinal juice. Unknown 1.011 Invertase, glycolytic. Maltase, glycolytic. Salts. Erepsin, proteolytic. 382 PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY. SALIVA. Normal saliva is opalescent, odorless, frothy, slightly cloudy, and faintly alkaline. The quantity of saliva is dimin- ished by atropin, in fevers, diabetes, nephritis, and severe diar- rheas; increased (salivation, ptyalism) by Hg, KI, pilocarpin, acids, and by mastication, pregnancy, and local inflammatory conditions. It has a bad smell in scurvy, gingivitis, and mer- curial salivation. It is acid in the morning before breakfast and sometimes after much talking, and may be constantly acid from oral fermentation (lactic acid), Hg salivation, and in rheu- matism and diabetes. When it is strongly acid, considerable galvanic action may take place with dental fillings or metal plates. Albumin is present in ptyalism; urea, in nephritis. The secretion of the parotid gland is most fluid; that of the sublingual and submaxillary more slimy. There is only a trace of ptyalin in saliva for some months after birth. Experiment. Test for mucin by adding to clear saliva acetic acid drop by drop, and note ppt. of mucin in white strings or flakes. Experiment. Test for sulphocyanate in saliva by filtering a small quantity and adding a drop of very dilute Fe 2 Cl . The red color disap- pears on adding HgCl 2 . This test is sometimes negative. Salivary calculi depend on inflammatory conditions, and are sometimes deposited in the salivary ducts. They are com- posed of CaC0 3 and Ca 3 (P0 4 ) 2 (cemented with organic matter), which salts are normally held in solution by C0 2 . Test for Hg in Saliva. Collect 100 c.c. or more of saliva, acidulate with HC1, digest on water -bath for two hours, adding now and then a drop of HN0 3 . Filter and concentrate to 10 c.c. Take a little of this in a test-tube, add a small fragment of bright Cu, and boil. If Hg is present, it will form a gray coating on the Cu, driven off by heating. GASTRIC JUICE. This is a thin, pale-yellow liquid containing 0.5 per cent, of solids. It is often mixed, however, as usually obtained, with viscid mucus from the throat. The normally frankly-acid re- action of gastric juice is due chiefly to the free HC1, partly to the acid phosphates. The HC1 is derived from common salt by the mass action of C0 2 or by reaction with the sodium bicar- bonate of the blood: NaCl + NaHC0 3 = Na 2 C0 3 + HC1 Free HC1 averages about 0.2 per cent, in the gastric juice. The amount increases from the beginning of digestion. It com- bines loosely with protein molecules and probably with pepsin. SECRETIONS. 383 HC1 is deficient (hypochlorhydria) in most cases of ordinary functional dyspepsia, and in fevers and renal, hepatic, cardiac, and pulmonary diseases. It is greatly diminished or absent in cancer of the stomach and chronic atrophic gastritis. Hyper- chlorhydria is usually a neurosis (often with hypersecretion = gastrosuccorrhea), and is a significant sign of gastric ulcer. Free HC1 is an effective germicide, though not destructive to spores. Bacterial fermentation, of carbohydrates mostly, with production of organic acids (lactic, acetic, and butyric) and alcohol, is therefore to be expected with hypochlorhydria. Hyperacidity may be due either to excess of HC1 or of organic acids. Mineral acids given before meals decrease the secretion of HC1; given after, they prevent the formation of organic acids. Alkalies before meals favor the secretion of HC1; given after meals they relieve acid eructations from any cause, but only for the time being. The fatty acids and simple gases (H, C0 2 , and CH 4 ) are also found in the stomach-contents in some cases of hyper- chlorhydria with retention; these cases are, however, not ac- companied by putrefactive changes. Frequent feedings also interfere with gastric self-disinfection. Lactic acid is not found normally after digestion has progressed for more than a half- hour, owing to the inhibiting action of HC1, or until the entire food mass has been permeated by the mineral acid. The suc- cus pyloricus is said to be alkaline, as is the reaction of the slimy secretion of the stomach in a state of rest. Fermentation is best prevented by restriction of carbohydrates and by the administration of HC1 in sufficient doses after meals. The stomach-contents generally contain a little mucus, which is greatly increased in the acute and the mucous forms of sub- acute and chronic gastritis. Experiment. Make NaH,P0 4 by adding H 3 PO 4 gradually to Na 2 - HP0 4 solution till it does not ppt. BaCl 2 . Show with litmus-paper that the acid phosphate thus formed is not neutralized by CaCO 3 , whereas free dilute acids are. Experiment. Make a 0.2-per-cent. solution of HC1. Show that it turns methyl-violet solution blue, congo-red blue, and tropeolin 00 from yellow to red. Experiment. Test the HC1 solution in a casserole by adding a few drops of a 5-per-cent. solution each of cane-sugar and resorcin. On warm- ing gently a red line appears at the border. Experiment. Make a 0.1-per-cent. solution of lactic acid; also dis- solve 0.1 c.c. of a saturated alcoholic solution of gentian-violet in 250 c.c. of distilled water, and 5 c.c. of official solution of Fe 2 Cl 6 in 20 c.c. of water. Add a drop of the iron solution to a drop of the gentian-violet solution, producing a bluish-violet color, which is turned greenish yellow by a few drops of the lactic acid. (See further under "Clinic Chemistry.") 384 PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY. BILE. Bile is a mixture of hepatic cell-secretion and of mucus derived from the gall-bladder and ducts, and is both a secretion and an excretion. It is thick, viscid, and very bitter, and varies in color from light yellow to greenish blue. It contains from 7 to 18 per cent, of solids (1 to 4 per cent, from a fistula). The chief bile-salts proper are the glycocholate and tauro- cholate of sodium, the former occurring in four times the quan- tity of the latter. They are dextrorotatory, and are pptd. as fine needles from alcoholic solutions by addition of ether. The office of these salts in digestion is to ppt. peptons in the small intestine, thus aiding their absorption. They also keep the fatty acids and lecithin and cholesterin in solution. Normal bile contains two pigments: bilirubin, or bilifulvin (C le H 18 N 2 8 ) (reddish yellow); and biliverdin (C 16 H 18 N 2 4 ) (green). The former is derived from hematin, and yields the latter by oxidation; on putrefactive reduction hydrobilirubin (stercobilin, urobilin) results. Biliverdin is insoluble in CHC1 3 , which dissolves bilirubin. Bile-pigment contains no Fe, which has been split off in the liver. Altered bile and bile-stones contain other pigments, such as bilifuscin (brown), biliprasin (greenish black), bilicyanin (bluish), and choletelin (yellow to brown). Gall-stones are composed chiefly of cholesterin, with a nucleus of calcium- bilirubin. Cholesterin calculi are whitish and greasy and float on water, and are commonly faceted because of friction in the gall-bladder. Bile-salts are formed only in the liver. Bile-pigments are formed normally in the liver, but also abnormally from the breaking down of red corpuscles and extravasations in other parts of the body. Thus, there are two kinds of jaundice: hepatogenous (usually obstructive, with lymph absorption) and hematogenous. Cholemia leads to destruction of red corpus- cles and circulatory disturbances. A diminished biliary flow into the intestine favors constipation and putrefaction. The total amount of bile, as well as the proportion of solids, is gen- erally diminished in fevers. A little greenish bile is commonly present in vomit when this is frequent or severe. The presence of bile in the stomach-contents drawn with a tube is suspicious of stenosis of the small intestine. The bile of one day, injected into the veins, would be sufficiently toxic to kill three men. Experiment. To some fresh ox-bile in a test-tube add twice as much water. Filter, if not clear, and add acetic acid. Note slight ppt. of mucin (more in human bile). SECRETIONS. 385 Experiment. Test for Bile-acids. Add to a few c.c. of well-diluted bile two-thirds its own volume of strong H 2 SO 4 , letting the acid run slowly down the side of the tube so as not to mix, and keeping the tem- perature below 70 C. Then add 2 or 3 drops of a 10-per-cent. cane-sugar solution, and shake gently. A pink, red, or violet color develops, with a pink foam. The reaction depends on the formation of furfurol. Albu- min or morphin gives a similar color-reaction. Experiment. Pulverize a small gall-stone and dissolve in a mixture of warm alcohol and ether. Decant into an evaporating dish and allow to evaporate spontaneously. Note the crystals under the microscope: thin, transparent plates with a notched corner. Experiment. Dissolve in a dry test-tube a few of the crystals in CHC1 3 , add an equal volume of H 2 SO 4 , and shake. A blood-red color ap- pears, turning cherry and purple, with a green fluorescence. PANCREATIC JUICE. The pancreatic secretion is clear, thick, and strongly alka- line,, and contains about 10 per cent, of solid constituents: two- thirds organic, one-third inorganic. The alkalinity is due chiefly to Na 2 C0 3 . Pancreatic calculi are rare and consist mostly of phosphate and carbonate of calcium, with a nucleus of animal matter. INTESTINAL JUICE. The succus entericus is a clear, viscid, light-yellow, opales- cent, strongly alkaline secretion, containing a little over 2 per cent, of solids, of which about one-third is inorganic. MUCUS. The protective fluid of mucous membranes is a glossy, translucent, colorless or opaque, stringy, generally alkaline secretion, containing 4 or 5 per cent, of solids, chiefly mucin. Microscopically it shows mucous corpuscles, epithelia, fatty granules, and sometimes cholesterin crystals. Mucus varies somewhat according to its place of origin. Thus, vaginal mucus is thin and acid, while that from the neck of the uterus is alka- line and resembles the white of egg. Excess of mucus accompanies irritation or inflammation of the part affected, and favors fermentation. TEARS. The protective secretion of the lacrymal glands is a clear, slightly alkaline fluid, containing 2 per cent, of solids, mostly NaCl, albumin, and mucus. The so-called tear-stone is a calci- fied mass of fungus. 386 PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY. SEBUM. The lubricating secretion of the sebaceous glands is an oily semifluid, which becomes a white, greasy solid on cooling. It is composed of fat, soaps, cholesterin, nucleo-albumin, phos- phates, chlorids, and epithelial scales. Obstruction of the gland-ducts leads to the formation of "black-heads," "wens," etc. The smegma of the external genitals; ear-wax, or ceru- men; and the vernix caseosa of newborn infants are sebaceous in character. MILE. The nutrient secretion of the mammary gland is a natural emulsion of fat-globules held in suspension by casein and cal- cium phosphate. Fig. 48. Human Milk and Colostrum. The average daily quantity of milk from a woman is about a liter; from a cow, six to ten liters (four times the body-weight in a year). The color is normally white or light yellow, human milk having more of a bluish tinge than cows'. Milk is colored blue by the bacillus pyocyaneus; blue, slimy, and bitter by tyrotoxicon; purple-red by the micrococcus prodigiosus; and yellow by the bacillus synxanthus. It is reddish yellow in rinderpest, owing to the presence of blood. Eopy milk is caused by a special bacillus during moist, warm weather. Inflamma- tion of the udder imparts a salty taste to milk. The reaction of cows' milk is usually amphoteric, because of the presence of both acid and alkaline sodium phosphate. Fresh human milk is generally feebly alkaline. The sp. gr. of milk ranges from 1.018 to 1.045. Healthy human milk is SECRETIONS. 387 from 1.028 to 1.033, with an average of 1.031. Healthy bovine milk ranges from 1.029 to 1.035. Breast-milk is thinner the less frequently it is taken. The solids in milk amount to nearly 13 per cent, normally, varying from 8 to 16 per cent. These comprise chiefly casein (3 per cent, in bovine, 1 per cent, in human), lactalbumin (0.5 per cent, in cows', 1 per cent, in woman's), fat (4 per cent, in woman's, 3.7 per cent, in cows'), lactose (6 per cent, in human, 4.5 per cent, in bovine), and mineral salts (0.2 per cent, in woman's, 0.7 per cent, in cows'), mostly Ca 3 (P0 4 ) 2 . Milk con- tains more lime to the liter than liquor calcis. Other salts are the phosphates of Mg, K, and Na; the chlorids of K and Na; and a trace of iron. Other proteins in traces are lactoglobulin (probably identic with serum-globulin), nuclein, pepton, and albuminoids. Still other unimportant ingredients are lecithin, leucin, creatin, and about 8 per cent., by volume, of gases (0, N, and C0 2 ). Milk is deficient in iron, but infants contain in their tissues a store of this metal that is slowly used up during the period of suckling. The composition of milk varies con- siderably from day to day, and the strippings are seven times as rich as the first few drops. The casein of milk is not in solution, but is held in gran- ular suspension; it can be filtered out by a clay filter as a fine, white powder. It dissolves readily in alkalies or mineral acids, and reddens moist litmus-paper. It does not coagulate on boil- ing, but, along with Ca, forms the scum. It coagulates quickly with acids or lab-ferment (rennet) in the presence of Ca 3 (POJ 2 , with which the casein unites to form the curd (paracasein), a small quantity of whey albumose being formed at the same time. Human casein can be pptd. by saturating with MgS0 4 . It forms a finer, more flocculent, and more digestible coagulum than cows' milk. Phosphocarnic acid is split off from human casein in digestion, and is peculiarly rich in P. Experiment. Fill two test-tubes one-half with milk, and to one add a teaspoonful of a good liquid rennet. Let stand for fifteen minutes. Then boil the milk in both tubes. Note that the milk containing the rennin gives a flocculent ppt., the other a heavy, curdy ppt. Quite fresh milk (except colostrum) does not coagulate on heating. Lactose is nearly constant in quantity in the same person. It ferments spontaneously at ordinary temperatures into lactic acid, which removes the phosphates and ppts. coagulated casein, forming the curd; the whey is the thin liquid left after re- moving the curd. In the curdling of milk there is also a slight evolution of C0 2 . Butter-fat appears in small, refractive globules 0.0015 to 388 PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY. 0.01 mm. in diameter (average, 3.7 microns) and averaging from 1 to 5.7 millions per c.c. It contains traces of lecithin and cholesterin and a little yellow coloring matter (lipochrome). Experiment. Confirm existence of fat-drop membrane by mixing some milk with a little KHO before shaking with ether. Solution is greatly aided, as is readily shown by a blank test. The laxative colostrum of the first few days of lactation is nearly one-fourth solids (sp. gr., 1.046 to 1.080), containing an excess of fat and proteins (no caseinogen) and numerous colos- trum corpuscles (epithelial cells, including fat-globules). Mothers' milk diminishes in fat and proteins near the weaning period. A fatty diet diminishes the quantity of milk. A vegetable diet increases the sugar and decreases proteins and fat. Meats cause an increase in both fat and proteins. Exer- cise diminishes proteins, Hg, As, I, Pb, Br, laxative salts, turpentine, and volatile oils pass into the breast-milk when taken internally. Organic acids taken by the mother cause griping in the nursing child. Worry, emotions, and menstrua- tion increase the proteins and render the milk somewhat poi- sonous to the infant. An insufficient milk-supply is usually best remedied by the free ingestion of fluids, especially broths and gruels. (See also under "Clinic Chemistry.' 7 ) SEMINAL FLUID. The secretion of the testicle is a white, opaline, viscid fluid, containing, as its essential principle, the spermatozoa, which are mobile in the alkaline fluids of the body, but soon lose their power of motion outside the body. Nuclein is the chief con- stituent of these cells; they also contain fat, lecithin, and cholesterin. The glue-like odor is due to spermin (C 2 H 4 NH), which, on standing, forms characteristic dagger, or cuttle-bone, crystals. The recognition of spermatozoa in stains is best accom- plished, according to Simon, by soaking a fragment of the cloth or scrapings for an hour or more in a watch-crystal containing 27 to 30 per cent, alcohol, then teasing a bit of the matter in a 1 to 200 solution of eosin in glycerin, and examining under the microscope. The heads of the spermatozoa are stained deep red, the tails pale rose. Vegetable fibers do not take up this stain. In addition to the spermatozoa, semen contains seminal and other granules, epithelial cells, and oil-globules. The ma- jor portion of an ejaculation consists of the secretion of the seminal vesicles, which contains many mucoid globules and SECRETIONS. 389 some granular phosphates. The prostatic secretion is a thin, alkaline liquid, containing granular phosphates, often grouped in colored microscopic concretions or sympexia. During sexual excitement Littre's follicles, Cowper's glands, and Morgagm's crypts pour forth a clear mucus like white of egg. This secre- tion is alkaline in reaction, and neutralizes and lubricates the anterior urethra. LYMPH. This is a clear, colorless, or faintly yellow or red, alkaline, coagulable fluid, which constitutes the interstitial nutrient Fig. 49. Spermatozoa and Bottcher's Crystals. liquid of the body and carries into the blood the retrogressive products of metabolism. It makes up perhaps one-fourth the weight of the whole body. It varies considerably in composi- tion, the solids averaging about 4 per cent, (chiefly albumin, fats, and NaCl), and in sp. gr. from 1.022 to 1.045. CHYLE. This is nearly identic with lymph, except during absorp- tion, when it contains considerable fat (over 3 per cent.), which gives it a creamy appearance, and more fibrin (0.2 per cent.). 390 PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY. It is strongly alkaline, and has a sp. gr. of 1.007 to 1.022. It is the mother-liquid of the blood. As it passes from the intes- tine into the receptacuhim chyli it loses albumin and fat and takes up corpuscles and fibrin, thus becoming coagulable. CEREBRO-SPINAL FLUID. The meningeal fluid obtained by lumbar puncture is clear (unless purulent) and frankly alkaline; sp. gr., 1.006 to 1.007. It contains less than 2 per 'cent, of solids, chiefly K and Na salts and more or less albumin above 1 per cent, in severe inflammations. Sugar is present in cases of brain-tumor. SYNOVIA! FLUID. The synovia is a clear, light-yellow, mucoid, alkaline fluid, containing from 3 to 5 per cent, of solids: mucin, albumin, fat, and salts. The consistency of the liquid is increased by much use of the joint. INTERNAL SECRETIONS. By this term is meant the specific non-excretory substances formed within glandular organs and given off directly to the blood or lymph. Like the secretions having external commu- nication, these have a special function in the maintenance of health. The formation in the liver and muscles of glycogen from dextrose, and the reverse change, are among the most impor- tant examples under this heading. Experiments on animals and autopsies on the human body seem to prove that the pan- creas furnishes the blood or lymph with an internal secretion necessary either to the normal consumption of sugar in the body or to the control of the sugar output from the liver and muscles. The function of the thyroids appears to be connected with metabolism, and when the glands are extirpated or atrophied the subject becomes diseased (myxedema) and succumbs. The essential secretion of the thyroid is thyroidalbumin, from which thyroidin is obtained by boiling with acids. Dry thyroidin is an organic compound containing nearly 10 per cent, of I. Suprarenal extract is a true internal secretion, and is a most powerful vascular tonic. Hence it is used for preventing and controlling hemorrhages. The active principle of the ex- tract is a pyrrol derivative called epinephrin, or adrenalin. The pituitary body is claimed by some authors to furnish an internal secretion relating to body-growth. The testes, EXCRETIONS. 391 ovaries, and other glands are also thought to exert special effects on the organism through internal secretions. EXCRETIONS. Excreta differ from true secreta in consisting chiefly of waste-products which are no longer of any service to the or- ganism. They pre-exist in the blood and accumulate in this fluid if not properly eliminated, giving rise to symptoms of poisoning. The principal waste-products of the human econ- omy are urea, C0 2 , H 2 0, NH 3 , the purin bodies, creatin, the inorganic sulphates and phosphates, the conjugate sulphates, and various pigments. The amount of urea excreted Varies from 2 or 3 grains per pound daily in sedentary adults to 3 1 / 2 grains per pound in active workers, and 6 to 10 grains per pound in children. URINE. This is the most important excretion, containing, as it does, nearly all the urea. The water and inorganic salts of the urine appear to be eliminated by simple osmosis and dif- fusion from the capillary tufts of the glomeruli. The urea is secreted by a special selective action of the cells lining the convoluted tubules. When the nutrition of these cells is im- paired by inflammation, malnutrition, or other causes, the urea is not fully excreted, and accumulates in the blood (uremia), while albumin and globulin escape from the blood into the urine. (See also under "Clinic Chemistry.") FECES. The alvine evacuations consist chiefly of water (75 per cent.); insoluble and indigestible residues (7 per cent.) of cellulose, resins, and albuminoids; inorganic salts (1.2 per cent.); mucus (12 per cent.); epithelia, fat-drops and fatty- acid crystals, cholesterin, indol, skatol, phenol, cresol, extract- ives, and bacteria. The daily solids should amount to 30 to 60 gm. The gases (CH 4 , H, N, and C0 2 ) are most abundant on a vegetable diet. The reaction of feces is normally neutral or slightly alka- line (normally acid in infants); occasionally acid from fatty- acid fermentation; rarely quite alkaline, with triple phosphates, in typhoid and dysentery (with free bile and much chlorids and albumin). The peculiar feculent odor is due to the putrefactive prod- ucts (from tyrosin), indol (C 8 H 7 N), and skatol (C 9 H 8 N), along 392 PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY. with H 2 S, H 3 P, and butyric and valeric acids. A meat diet makes the stools smell stronger. The extremely foul odor of naphthylamin is sometimes noted after eating fish. Acholic stools are generally fetid in odor. In the green, acid diarrhea of infants from fermentation of carbohydrates the feces smell sour. In the more severe leaden-gray, pultaceous form a putrid odor, due to albuminous putrefaction, is noted. The charac- teristic odor of cadaverin is marked in dysenteric and choleraic evacuations. In the gangrenous variety of dysentery and in syphilitic and carcinomatous rectal ulceration there is a very offensive rotten stench. The color of the stools varies from light yellow (alkaline diet) to dark brown (meat diet), and depends normally on changed bile-pigment (stercobilin). The green color noted in summer diarrhea may be caused either by biliverdin or by the green bacillus of le Sage. Excess of unchanged bile makes the color green. When the bile is deficient the stools are pasty and clayey in color. White, fatty stools also accompany pan- creatic disease. Undigested casein often appears in white lumps in the discharges of infants. After taking calomel or ipecac the stools are spinach-green. Fe, Mn, Bi, and Pb salts darken the stools, owing to the formation of the sulphid or oxid of the metal. Santonin, rhubarb, and senna cause yellow stools. Starch tends to produce a yellowish tinge; .chlorophyl, a green; cocoa, a gray; red wine, blackish. The evacuations are serous in cholera infantum. The rice- water appearance of albuminous cholera feces is due to large numbers of epithelia. Catarrhal conditions are accompanied by excess of mucus, sometimes forming pseudocasts of the bowel. Mucus from the small intestine is well mixed with the feces. Blood in the stools is bright colored if from the large in- testine; dark and tarry (hematin), from the stomach or small intestine. Blood and pus appear in dysentery, ulcerative con- ditions generally, and perforations of extra-intestinal abscesses. Leucin and tyrosin are found in cholera feces. Urea is excreted in considerable quantities by the intestine in uremic conditions. It quickly changes to ammonium carbamate, which by its irritating action on the mucous membrane causes the so- called critic diarrhea and vomiting. In constipation and fecal impaction water is reabsorbed and the excrement forms hard scybala with mucus. The viscid meconium of the newborn owes its dark color to altered bile. Micro-organisms and their spores are absent till after suckling. Intestinal concretions, bezoar, or enteroliths, are rarely EXCRETIONS. 393 met with in human subjects. They may consist chiefly of earthy phosphates, of fatty matters, of hairs, of vegetable fibers (oatmeal), or of insoluble medicines (bismuth salts). SWEAT. The average daily amount of perspiration is from 700 to 900 c.c. It is a highly-aqueous liquid, containing only 1.2 per cent, of solids and having a sp. gr. of 1.004. The chief solids are the alkaline chlorids (especially NaCl), sulphates and phos- phates, cholesterin, urea, and epithelia. The fatty acids (acetic, formic, propionic, caproic), ethereal sulphates, and purin bodies are present when sweating is profuse. About 2 gm. of C0 2 is given off by the skin in twenty-four hours. The amount of urea excreted by this route is markedly increased in uremic conditions, and glistening crystals of the compound may some- times be seen on the skin; vapor-baths have the same effect. Freshly excreted sweat is usually slightly alkaline in reac- tion, but may be acid. It may be colored yellowish from bile, blue from indican, red from blood. It is very acid in acute rheumatism and in rickets. It is strongly alkaline (ammoniacal) in uremia. lodin, iodids, organic acids, and other drugs may appear in the sweat after their administration. The skin eruptions sometimes following the ingestion of berries and shell-fish may be caused by the local irritation of organic acids and intestinal decomposition products. The ill effects of coating the skin with varnish are due, not to checking of perspiration, but to resulting dilation of cutaneous vessels and consequent loss of heat. VOMIT. Vomiting of undigested food some hours after meals is noted in gastric atrophy or anadeny. Vomiting of well-digested food occurs in stomach neuroses, gastric ulcer, and acute or subacute gastritis and in central emesis. Morning vomiting of food taken the day before indicates some interference with gas- tric motility, usually accompanied by dilation and fermentation. Morning vomiting also occurs in alcoholic subjects and patients with chronic pharyngitis, from the swallowing of mucus and saliva. Bile and pancreatic juice are nearly always present in vomit when severe or protracted, and the former is readily dis- tinguished by its color. Bright blood is characteristic of gastric ulcer, in which considerable quantities are lost. Small amounts of blood are changed to hematin by the acid gastric juice, giving rise to the 394 PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY. black, or "coffee-ground," ejections of gastric cancer and he- patic cirrhosis. Pus in vomit is generally due to the perforation into the stomach of an adjoining abscess. Stercoraceous vomiting is easily recognized by the odor, and is indicative of intestinal obstruction. A feculent odor is also sometimes observed in cases of enterostenosis and in sub- jects with a fistula between the stomach and the intestine. The odor of vomit may be putrid in gastric carcinoma and in pyloric obstruction from any cause. An ammoniacal odor is observed in uremic vomiting; a garlicky odor in P poisoning; carbolic and hydrocyanic acids give characteristic scents to the vomit. The regurgitated material from an esophageal sac or strict- ure is easily distinguished from true vomit by the total absence of all gastric elements. SPUTUM. The chemistry of the sputum is of no great relative im- portance. The daily quantity may exceed a pint in cases with large cavities. The color and opacity depend chiefly on the contained leucocytes. The following crystals are occasionally met with: Hema- toidin (following extravasations of blood), cholesterin (stag- nant pus), fatty-acid needles (putrid conditions), calcium oxa- late, triple phosphates, leucin, tyrosin, and the Charcot-Leyden crystals. These last are long, sharp octahedra, having the for- mula C 2 H 5 N. They are most frequently observed in asthma, and are chemically identic with spermin. They represent a retrogressive cellular metamorphosis and are found in decom- posing viscera. Particles of silica or stone-dust are observed in chalicosis; of coal-dust in anthracosis; of iron in the siderosis of grinders; and of kaolin in the sputum of potters and brick-makers. CaC0 3 concretions may come from the tonsillar crypts or from old pulmonary cavities, and the same is true of fetid cheesy particles. Earely a blue tinge is noted in tuberculous sputum, due to ferrous phosphate. CYSTIC CONTENTS. Ovarian and parovarian cysts may contain either a clear, straw-colored fluid (red-brown if hemorrhagic) of low sp. gr. and with little albumin, or a dense, glairy, colloid material (1.018 to 1.024) with a large amount of serum-albumin, serum- globulin, and metalbumin. This last protein is very character- istic of ovarian cysts. It may be demonstrated, according to EXCRETIONS. 395 Simon, by mixing the fluid with three times its volume of alco- hol, setting aside for twenty-four hours, and filtering. The filtrate on boiling becomes cloudy, without a ppt., however. It gives no ppt. with acetic acid, but with this acid and potas- sium ferrocyanid thickens and turns yellowish. H 2 S0 4 gives a violet color, and boiling with Millon's reagent a bluish red. Cholesterin crystals are generally quite numerous. Hydatid fluid is clear, alkaline, and non-albuminous; sp. gr. 1.006 to 1.010. NaCl is abundant, and succinic acid is usually present. Seeing the characteristic booklets under the micro- scope is the final test. The fluid of pancreatic cysts is recognized by its power of digesting albumin in alkaline solutions. Milk may be employed as a test-medium, using the biuret reaction after pptg. the casein. A negative result does not exclude a pancreatic origin, since trypsin is not present in very old cysts. The finding of urea in notable quantities readily distin- guishes a hydronephrotic cyst from any other, even when the liquid has no urinous odor. Eenal epithelial cells are also quite characteristic. TRANSLATES AND EXTTDATES. The pathologic accumulation of fluids in the serous cavi- ties and areolar connective tissue (under skin and between muscles) is termed an exudate when inflammatory in origin; a transudate when non-inflammatory (heart, blood, or kidney diseases). The sp. gr. of exudates ranges from 1.018 to 1.030 (the older, the denser); of transudates from 1.005 to 1.015. The difference is attributed to the amount of albumin: 4 to 6 per cent, in exudates, 1 to 2 per cent, in transudates. Bxudates often coagulate spontaneously after standing twenty-four hours; transudates do not coagulate unless from the presence of blood. Considerable gas, chiefly C0 2 , is frequently developed in these fluids. Transudates are generally serous and of a light-straw color (tinged reddish if blood is present); rarely they are chylous. Hydrocele fluid contains nearly 5 per cent, of serum-albumin and serum-globulin. Plates of cholesterin are often found in old serous transudations. Anasarcal fluid is clear and watery (1.005 to 1.010), and contains about 0.5 per cent, serum-albu- min and 0.1 or 0.2 of urea. Ascitic fluid is yellowish, has a sp. gr. of 1.008 to 1.012, and contains from 0.7 to 0.9 per cent, of inorganic matter. It is chylous in tubercular peritonitis. Exudates may be serous, serofibrinous (serosanguinolent), seropurulent, purulent, putrid, hemorrhagic, or chylous. Serous 396 PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY. exudates resemble transudates, and have a sp. gr. usually above 1.008. Hemorrhagic exudates into the pleura are most fre- quent in cases of pulmonary tuberculosis and carcinoma, which are distinguished from each other by finding cancer-cells and fat-droplets in the latter instance; tubercular exudates are usually sterile. Putrid exudates are brown or greenish brown and alkaline (except from perforation of gastric ulcer), and are readily rec- ognized by the odor. Purulent exudates vary in color from gray-yellow to green-yellow, and in sp. gr. from 1.020 to 1.040. They are alkaline when fresh (pleural may be weakly acid), and have the same chemic composition as white blood-corpuscles, with addition of pepton. Empyema following pneumonia is likely to contain large clumps of fibrin. Leucin and tyrosin are often present in old abscesses. The fluid from uterine cysts differs from amniotic liquid in containing more albumin and but a trace of urea. This dis- tinction is of some importance as regards watery discharges from the uterus during pregnancy. ANIMAL FUNCTIONS. All the phenomena of the living body are caused directly or indirectly by chemic changes. Every pulse, every breath, action, and thought involves intricate reactions, which are more or less imperfectly understood. DIGESTION. The process of digestion consists essentially of hydrolysis: i.e., the taking up of water by food-products and their breaking down into simpler molecules capable of diffusion. The end- product of amylolytic digestion is dextrose; of proteolytic, pep- ton or amido-acids. Fats are simply saponified and emulsified. The mixed acid products of digestion in the stomach are termed chyme. The reaction becomes alkaline (latter part of digestion) by the middle of the small intestine and remains so to the ileo- cecal valve; it is often acid below this point, owing to fermenta- tion. Peptons stimulate gastric secretion. A piece of well-masticated bread is changed by the ptyalin of the saliva into amylo-, erythro-, achroo-, and malto- dextrin, and partly into maltose. The amylolytic action of the saliva continues in the stomach for about a half-hour after the food is swallowed, or until the acid gastric juice permeates the whole DIGESTION. 397 mass. The conversion of starches into maltose is completed by the amylopsin of the pancreatic juice, which is by far the most active digestive secretion in the body. The maltose and any cane-sugar or lactose which may have been present in the bread are inverted by the invertase (maltase or lactase) of the intestinal juice. The butter on the bread is not affected by saliva, but is liquefied by gastric juice, which seems to break down the mem- branes of the fat-drops, causing them to run together. In the duodenum it is acted on by both the bile and the pancreatic juice. The steapsin of the latter cleaves oils and fats into glyc- erin and fatty acids. These latter form a little soft soap with Na 2 C0 3 , and the soap emulsifies the remaining fats. The action of the bile is similar. C 3 H 5 (C 18 H 35 2 ) 3 + 3H 2 = 3C 3 H 5 (OH) 3 + 3HC 18 H 35 2 A piece of meat or an egg is first changed to syntonin by the gastric HC1, then to albumoses (proto-, hetero-, and deutero-, or secondary), and finally to amphopeptons (hemi- and anti-; half and half in vitro; anti- much exceed hemi- in intestine), the last change being effected chiefly by the trypsin of the pancreatic juice. Fibrin swells up, becomes transparent, and is corroded by the gastric juice; by trypsin it is first changed to globulin. Albumoses differ according to the proteins from which they were derived, and are often designated as globulinose, caseose, etc. Peptons are pptd. by the bile-salts, thus favoring absorption. Hemipeptons are converted by trypsin and erepsin into leucin, tyrosin, and tryptophan. This last, also known as proteino-chromogen, is related to bilirubin and melanin, and may be utilized in building up hemoglobin and other pigments. It gives a purple-red color with Br water. Antipepton, C 10 H 15 - N 3 5 , is isomeric with sarkinic acid, from the phosphosarkinic acid of muscles. It resists the change into leucin and tyrosin. Milk undergoes similar digestive changes to the three men- tioned above, with the addition of a curdling process due to chymosin. Connective tissue is digested by the gastric juice, but not by the pancreatic. Nucleo-proteids leave a residue of nuclein, called dyspepton in the case of fibrin. Keratin is alto- gether indigestible. Experiment. Digest in three porcelain dishes by means of (1) pepsin and (2 and 3) pancreatin, a small disk of egg-albumin, a dram of hydrated (boiled) starch, and a few c.c. of codliver-oil. Test con- tents of first dish frequently for the digestive products syntonin, albu- mose, and pepton; of the second for dextrins, maltose, and dextrose; PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY. and note rapid saponification and emulsification of oil. The pepsin dish is best kept in a thermostat at 38 to 40 for two hours or more. The amylolytic process can be finished at about the body-temperature in less than a half-hour. Take care not to heat much above this point. Intestinal bacteria aid somewhat in digestion, especially the liquefying ones, but their chief action consists in the pro- duction of skatol, indol, phenol, cresol, NH 3 , H 2 S, leucin, tyrosin, aspartic acid, and tryptophan from proteins; lactic and butyric acids from starches and sugars; fatty acids from fats; and CH 4 and C0 2 from cellulose. The chief fermentation prod- ucts in the stomach are alcohol and lactic, acetic, and butyric acids. ABSORPTION. The process of absorption depends on osmosis and diffusion and on a special action of the cells of the alimentary mucous membrane. Alcohol, sugar, and many medicines are absorbed to some extent from the mouth, stomach, and rectum, but the small intestine is the chief route of entrance for alimentary products. Water is not absorbed from the stomach. Proteins are absorbed into the blood and lymph as dif- fusible amphopeptons, albumoses, and amido-acids, which are dehydrated and regenerated (polymerized) by the gastric and the intestinal mucous membrane into the colloid serum-albumin and globulins of the blood. The direct injection into the blood of proteoses or peptons has a toxic effect, and large doses may produce coma or even death. Carbohydrates are taken up by the rootlets of the portal vein and carried to the liver chiefly as dextrose; but maltose, levulose, and lactose may also reach absorption in small quan- tities. The glucose is stored in the liver as glycogen, and is given off again gradually as dextrose to the muscles and other tissues. Senility, obesity, toxins, neurasthenia, and the gouty habit all interfere more or less with the glycogenic function of the liver or sugar consumption by the tissues, and may lead to glycosuria or diabetes mellitus. Experimental nervous le- sions (floor of fourth ventricle) and injuries to the head cause a sudden expulsion of glycogen from the liver, with glycosuria. The most constant organic lesion in true diabetes is pancreatic disease. The ingestion of a large amount of sugar may cause temporary alimentary glycosuria, whereas starch has no such effect. Cane-sugar injected directly into the blood cannot be ABSORPTION. 399 utilized by the tissues, and it passes out unchanged in the urine. Fats are absorbed by the lacteals almost entirely in the form of a fine emulsion or chyle. Free fatty acids and soaps appear to be regenerated into fats during their absorption under normal conditions. The bile greatly aids the absorption of fats by its lubricating action on the mucous membrane. Hence in liver disease there is much waste of fat in the stools. In disease of the pancreas fat absorption ceases, except in the case of milk, a natural emulsion. Highly crystalline substances (KI, LiCl) are absorbed within five to fifteen minutes after their administration by the mouth. Others salol and keratin-coated pills, for example are not acted on by the gastric juice and are not absorbed from the intestine and found present in the urine for two hours or longer. The gastric HC1 appears to hinder exosmosis. Strych- nin solutions are absorbed more quickly from the rectum than from the stomach. During the passage of the contents through the large intestine a period of twelve to twenty-four hours much water and some nutriment is absorbed from them. The rectum and colon are able to absorb undigested nutrient ene- mata, such as eggs, milk, and salt, though no enzyme is found here. The limit of absorption of egg-albumin from this loca- tion is about 50 grams daily. Any substance to be absorbed, generally speaking, must be in the liquid or gaseous state, but finely divided charcoal taken internally has been found in the mesenteric veins. The rate of absorption varies inversely with the density of solution. Concentrated saline solutions cause more effusion from the blood-vessels than absorption into these; hence such hydragog purgatives as Epsom salts should be given in a minimum of water to get the best effects. Absorption is aided by low blood-pressure, and the saline infusions injected into the rectum or subcutaneously in cases of shock or hemorrhage are drunk up greedily by the vessels. Obviously the more rapid the circulation, the more quickly ab- sorption proceeds. Absorption from the stomach is facilitated by the use of condiments. Medicines administered hypodermic- ally are taken into the circulation very quickly unless the tis- sues are water-logged. Absorption through the unabraded skin seldom takes place unless rubbing is employed, as in mercurial inunctions. The absorption of poisonous gases (HCN) through the lungs is the most rapid cause of death. 400 PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY. METABOLISM. The anabolic or constructive chemic processes of assimila- tion by which the end-products of digestion become bone and flesh and gland and nerve still possess more of mystery than of knowledge. From the transuded blood, or lymph, the parent fluid or soil, each differentiated protoplasmic portion of the organism takes those elements which are needed for its _ sus- tenance and structure, generally a loose and unstable combina- tion of specially modified proteins, with inorganic salts. It is a curious fact that each of the circulating proteins shows minor differences when the blood is taken from different parts of the body. Catabolism includes oxidation and hydrolysis; anabo- lism, dehydrolysis. Protein foods and salts are absolutely necessary for tissue- building. Carbohydrates are essentially producers of energy and heat. They can be formed -from fats or proteins. The body-fat is derived chiefly from carbohydrates; to a minor degree from other fats and proteins (lack of oxygen). The adipose tissues serve chemically as potential reservoirs of heat. Albuminoids, such as gelatin, save the tissues more than carbo- hydrates do. Food-products may be said to crowd out the waste-products from the cells, forming new molecules, which speedily undergo dissolution in a continually recurring cycle. The oxidation of these complex molecules, chiefly in the tissues (perhaps some fuel foods, such as alcohol and glucose, are partly burned in the capillaries), gives rise to animal heat and mechanic energy as results, and as products the simple and more stable compounds, such as C0 2 , H 2 0, NH 3 , and urea. In other words, potential energy becomes kinetic through the agency of protoplasm, with catabolic or destructive phenomena, Tissue or bioplasm proteid is supposed to break down at the rate of about 1 per cent, per diem. An acid reaction quickly destroys the irritability of bioplasm. Inorganic salts normally neutralize the acids formed by metabolism. These two opposite processes of anabolism and catabolism go on constantly and almost simultaneously, and the life of the cell depends on the intramolecular atomic movements. Accord- ing to Pfliiger, in the living molecule N exists in the form of an unstable CN compound, which has the power to convert dead to living labile proteid by a process similar to polymeriza- tion or condensation. Catabolism, or the breaking down of living labile proteids, has been likened to putrefaction, with the evolution of N", H, and C, which combine with and with each other to form the simple end-products NH 3 , H 2 0, and METABOLISM. 401 C0 2 . Living protoplasm is believed to consist of "larger, sec- ondary units'" (physic or physiologic molecules, somacules), "each of which is a definite aggregation of chemic molecules, and possesses certain properties or reactions that depend upon the mode of arrangement." These somacules are suspended in a saline, alkaline, electrolytic fluid, and the protoplasm can be changed through gellation from the state of a hydrosol to that of hydrogel by heat, acids, electricity, or the abstraction of water. The recent researches of Loeb and Mathews point to the proposition that what we know as life is in the main an electrochemic phenomenon due to the gellation of protoplasm and the liberation of free-moving ions of different valences, the cations being inhibitory, the anions stimulating in their phys- iologic effects. Experiment. Add a little indigo-blue to a cane-sugar solution. The indigo is reduced by the sugar and loses its color (indigo-white). On shaking with free access of air the color is restored. Muscular energy is accompanied by increased oxidation of fats and carbohydrates (glycogen), with no appreciable increase in proteid metabolism if the food-supply is sufficient. The amount of C0 2 eliminated during ordinary muscular work is nearly double that while resting. Glycogen and the circulating glucose diminish or disappear from the active muscle, lactic acid being found. Four-fifths of the energy liberated by chemic changes dur- ing muscular contractions appears as animal heat, and the remaining fifth of mechanic energy in the case of the cardiac and respiratory muscles is also converted into heat. The glands, particularly the liver, generate considerable heat, and the brain and nerves liberate no small amount when in action. Animal heat depends primarily on the oxidation of fats, carbo- hydrates, and proteins in the capillaries (slightly, especially the pulmonary) and the tissues, with formation of C0 2 , H 2 0, NH 3 , urea, etc., in a somewhat analogous manner to the production of smoke, steam, and ashes by the engine. About four times as much heat is radiated from the skin as passes off from the lungs and in the urine and feces. About one-seventh of the body-heat is rendered latent by evaporating the perspiration; 1 gm. water = 0.582 calorie. The total available potential energy of any foodstuff is readily estimated by burning a certain quantity in a calorimeter, which is a sort of furnace surrounded by a given weight of water. From the rise in temperature of the liquid the number of calories, or "combustion equivalent," is calculated. In the 402 PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY. case of proteins oxidation is not so complete within the body as without, urea, the chief product, not being completely burned. The combustion equivalent of urea is 2.523 calories. One gin. of proteid yields about 1 / 3 gm. urea; hence, to get the average available energy of protein food to the body 841 calories must be deducted from the theoretic equivalent: thus, 5.778 0.841 = 4.937. The equivalents of fats and carbohy- drates are, respectively, 9.312 and 4.116 calories. An acid reaction quickly destroys the irritability of bio- en \ENT Fig. 50. Reichert's Water-calorimeter. plasm. The inorganic salts of the body-fluids neutralize the acids formed in metabolism. During starvation the circulating proteins are first drawn upon, then the body-fat (perhaps reconverted into dextrose), and then the muscles, to nourish other tissues and maintain body-temperature. Hence the loss of protein is greatest during the first day or two of fasting. A well-nourished adult, drink- ing an abundance of water, can keep alive without food for six weeks or more, while a delicate child would succumb within a week. Death from starvation supervenes with coma and delir- RESPIRATION. 403 ium after the body-weight is reduced from one-third to one- half. The elective affinity of the ingredients of glandular cells for certain waste-products in the blood, as of the kidneys for urea, is a chemic problem still unsolved. The formation of true secretions by gland-cells, as HC1 and pepsin, must depend, in general, upon a specialized protoplasmic metabolism. These cells in giving forth their secretion products seem themselves to break down and dissolve. The possible uses of the waste- products of one tissue for the needs of another is exemplified by the burning of sarcolactic acid to form uric acid. The interstitial circulation of lymph, from which the fac- tors of metabolism are obtained and by which the waste-prod- ucts are taken up to be excreted, is maintained normally by a delicately adjusted osmotic and diffusion process. The dif- fusion of soluble constituents takes place continuously from the side of greater concentration to that of less (out of or into the capillaries), and is not dependent on the osmotic water- current; lymph may become more concentrated even than plasma. The blood-capillaries are more permeable to urea than to salt or sugar: a fact which favors the excretion of the former compound. The osmotic pressure of serum proteins is about 30 mm. in the capillaries (only 10 mm. in the lymph-vessels): a constant factor in promoting resorption from the tissues. Lymphagogs, such as sugar and neutral salts, increase the osmotic pressure of the circulating blood, thereby attracting water from the lymph and tissues, producing hydremic plethora, rise of capillary pressure, and great increase in transudation, and hence in the lymph-flow. Intracapillary blood-pressure is ordinarily 30-50 mm. Hg. When it falls below 20 mm., ab- sorption of water from the lymph-spaces results. When the balance is broken and transudation becomes excessive, we have the condition of dropsy, ascites, or anasarca. Dropsic states are relieved by a dry diet and by diuresis, both of which promote low blood-pressure with increased osmosis into the capillaries. RESPIRATION. The respiratory changes effected in the blood are briefly a gain of (8 per cent.) and a loss of C0 2 (7 per cent.). The latter is under high tension through the acid action of the red corpuscles and serum-albumin on NaHC0 3 ; about 5 per cent, of the gas is in simple solution. The is taken up at once by the hemoglobin (0.26 volume per cent, free) and carried 404 PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY. to the tissues, where tension is nil and C0 2 tension high, and hence internal respiration takes place with a loss of and a gain of C0 2 . The is probably united with the protoplasm in a somewhat firmer union than oxyhemoglobin. The minimal constant of dissociation of oxyhemoglobin is 1 / 30 to V 10 atmos- phere. The pressure is less by over 20 per cent, in the alveoli than in the nares. This tension of in alveolar air is about 22 mm.; the tension of in arterial blood is 29.64 mm.; in venous blood, 22 mm. The alveolar tension of C0 2 at sea-level is 38 mm.; in venous blood, 41 mm.; in arterial blood, 21.28 mm. The muscles have the greatest avidity for of any of the tissues. The volume of air respired at each respiratory act is about 500 c.c., equivalent to 450 liters per hour or 380 cubic feet per day. Inspired air contains nearly 21 per cent., by volume, of and 0.04 volume of C0 2 . Expired air contains 16 volumes per cent, of and 4.38 per cent., by volume, of C0 2 . The tem- perature of expired air is raised to 36.3, and the actual volume of air is diminished 2 to 2 */ 2 P er cent., when allowance is made for the expansion (10 or 12 per cent.) caused by the rise in temperature. Expired air is saturated with water (20 to 40 gm. per hour) and contains traces of NH 3 and other organic effluvia, which give rise to the bad odor of ill-ventilated sleeping-rooms. Cutaneous respiration in man is of minor importance, the ratio with pulmonary respiration of absorbed being about 1 to 100; and of C0 2 eliminated, 1 to 200-500. Dyspnea develops when inspired air contains less than 13 volumes per cent, of 0, and is also caused by excess of C0 2 in the blood. The cyanosis observed in asphyxia from deprivation of air is due to the nearly complete reduction of oxyhemoglobin. The hemorrhages and other symptoms of caisson disease are attributable largely to the sudden escape from the blood of air which has been forced in under high pressure. POOD AND DIET. The purpose of food is to sustain life; to produce mus- cular, nervous, and glandular energy and heat; to promote growth; and to prevent the too rapid destruction of the or- ganic constituents of the body. The three chief classes of food are proteins, or tissue-formers; and the fuel foods, fats and carbohydrates, both of which are chiefly producers of heat and FOOD AND DIET. 405 energy. Proteins are also the source of the digestive fluids, and regulate oxidation and energy. One gm. of protein burned outside the body yields 5.778 calories or 1812 kilogrammeters; 1 gm. of fat, 9.312 calories or 3841 kilogrammeters; 1 gm. of glucose, 4.116 calories or 1657 kilogrammeters. These figures are the same practically for combustion within the body, except in regard to proteins, as already explained. The human body utilizes as dynamic energy a little over half of the potential energy of the food ingested. A steam-engine can utilize only one-eighth of the potential energy of fuel. The daily quantity of calories (heat, energy, and tissue- repair) required to keep the healthy adult human machine in good working order has been reckoned at from 2400 to 6000 (average, 3500), much more being needed when at hard mus- cular labor than when at rest. Such calculations are based mainly on examination of the excreta. Thus, 1 gm. N = 6 */ 4 gm. albumin = 29.4 gm. muscle = 2.143 gm. urea. Again, a man weighing 150 pounds gives off about 15 cubic feet of C0 2 in 24 hours, equivalent to 2400 foot-tons of energy. Allowance must also be made for the heat or energy required to keep up the body-temperature. It is possible for a person to live entirely upon proteins, but not upon a non-nitrogenous diet for any length of time. Nearly all foods contain more or less proteins: wheat, 14.6 per cent.; barley, 12.8 per cent.; oats, 17 per cent. An excess of proteid food above the amount needed to repair tissue-waste is burnt up into urea and excreted without serving any useful end; indeed, on the contrary, it overtaxes the liver and the kidneys, causing functional (lithemia) or organic disease of these organs. Excess of carbohydrates is stored up as adipose tissue. Fatty foods, it will be noted, yield much more heat than do proteins or carbohydrates; hence in winter and in cold regions people desire and require more fats. The most healthful and economic diet is evidently one so balanced as to nitrogenous and non-nitrogenous foods that there is no excess or lack of either. The proper proportion of N to C has been estimated to be about 1 to 15. Parke states that a working man needs 2 / 3 oz. N" and 8 to 12 oz. C daily. Another daily diet table is for proteins 110. gm. at rest, 118 gm. at moderate labor, 145 gm. at severe work; fats, 50, 55, and 100 gm., respectively; and carbohydrates, 450, 460, and 500 gm., respectively. Vaughan states that such requirements are most cheaply fulfilled by a diet of bread, codfish, lard, pota- 406 PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY. toes, bacon, beans, milk, sugar, and tea. The total weight of food per diem for an average adult should be about 60 oz. A slightly alkaline reaction favors gastric secretion and digestion. The proportion of N to C in proteins is about 2 to 7; in albuminoids, 2 to 5 V 2 . In fats there is about 1 H to 7 C, with not enough to burn all of the H, forming water. Carbo- hydrates have just enough to oxidize the H, and the weight of H is V 6 or 1 / 7 that of C. Organic acids have more than enough to burn the H. If a person were to live upon lean beef alone 2 or 3 kgm. would be required daily to get enough non-nitrogenous ele- ments; and of potatoes alone (less than 2 per cent, proteins), 8 kgm. would be needed to furnish enough N. Fats and carbohydrates are more needed by the young, who seldom get fat on account of their greater activity. Fats and albuminoids save the tissues and are especially indicated in chronic febrile diseases, such as pulmonary tuberculosis. In addition to the three classes of nutriment above men- tioned, water" and salts are very necessary. Of the former, three pints or more daily should be drunk by the average adult in addition to that taken in solid food (50 to 60 per cent.). A lack of water to flush the sewers of the body leads to constipa- tion, malassimilation, melancholy, and many obscure aches and pains. Water is best taken mostly between meals, so as not to dilute unduly the digestive juices. A glass of ice-water taken at a meal drives the blood from the stomach and delays diges- tion at least an hour. Common salt is the essential source of the HC1 of the gastric juice, and since functional indigestion consists in hypo- chlorhydria in three-fourths of all cases, many dyspeptics find much relief from eating largely of salted meats, salted crackers, etc. The reason why man and the herbivora require salt added to their food is explained by Bunge as due to the K salts uniting with the NaCI of the blood to form KC1, of which the excess now passes out of the system, causing thereby a loss of NaCl as well. Eice contains no K salts, and rice-eating races require no salt. Of other food-salts the phosphates are most important, being bone-, brain-, and nerve- formers. Fish is richest in phosphates, particularly salmon (6 to 7 per cent.). Flake-barley contains 4.2 per cent.; oats, 3 per cent.; wheat, 1.6 per cent. The phosphates are just under the hard, siliceous coat and on the surface of the kernel. Butchers' meat contains about 2 per cent, of phosphates; ham, 4 Y 2 per cent.; and beans, 3 per cent. FOOD AND DIET. 407 ANIMAL FOODS. These are generally more rapidly and completely digested than vegetable foods. Human milk is the ideal food for in- fants. Cows' milk lacks C as a sole article of diet for adults. It is usually quite fattening, partly because of its ready ab- sorbability and partly because of the lactose in it. It predis- poses to constipation, because there is hardly any residue left from digestion. The "bilious" effect of milk is obviated by adding 30 grains of common salt to each pint, and by eating fruits. Whey and junket are delicate dishes for the sick and convalescent, and buttermilk is often tolerated when rich milk is ill borne. Condensed milk is preserved by the addition of sugar, and while it fattens infants it is not nearly so nourishing as properly diluted fresh dairy milk. The milk of goats and asses is said to more nearly resemble human milk than does the milk of the cow, but the difference is too slight to be of account. Kefir is three times as rich in albumin as koumiss, and half as rich in alcohol and lactic acid. Boiled milk requires two hours to digest. It is less digestible than unboiled milk, but curdles in small flocculi instead of large masses, and so is more thor- oughly exposed to the action of the gastric juice. Cheese contains up to 27 per cent, of proteins (chiefly casein) and up to 30 per cent, of milk-fat, with about 5 per cent, each of sugar and salt. It is highly nutritious, but some- what indigestible unless very thoroughly masticated. The practice of keeping cheese until it has been "cured" that is, putrid from butyric acid fermentation (Limburger, Roquefort) is in contravention to all hygienic principles. In digestibility the meat of fish ranks first (trout, 1 1 / 2 hours), that of birds second (turkey, 2 V 2 hours), mammals third (roasted beef, 3 hours; mutton, 3 */ 4 hours; veal, 4 hours; salt beef, 4 1 / 4 hours; roast pork, 5 1 / 4 hours), and reptiles fourth. The flesh of young animals is less digestible than that of older. Meats contain from 25 to 50 per cent, of fats and proteins. The amount of water varies from 15 per cent, in dried bacon to 72 per cent, in lean beef and mutton. The proteins of meat are more completely digested than those of milk. The rotting of game until it is "high" aids digestibility by the corrosive action of sarcolactic acid on the sarcolemma, but it is a dangerous practice. Uncooked meat is liable to give rise to trichiniasis or a tape-worm. The brown color of well-done roast beef is due to hematin. The peculiar odor and flavor of meats depend largely on creatin and osmazome (developed by 408 PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY. heating). Creatin is the chief ingredient of meat-extracts, which are stimulating, but not nourishing, and are excellent media for typhoid bacilli. They aid the system to digest and utilize gelatin. The so-called peptonized or predigested foods, such as somatose, consist almost entirely of albumoses, and serve a useful purpose in many instances of malnutrition. If artificial proteolysis is carried too far, the products become bitter from some unknown substance. Eggs contain egg-albumin and vitellin, a ferronuclein, the common fats and a yellow lutein (lipochrome), a little dextrose, lecithin, cholesterin, and chlorid and phosphate of K and Ca. Eggs are savory and digestible and very nutritious, but undergo putrefaction readily, often causing eructations of H 2 S and H 3 P. According to the observations of Beaumont on St. Martin, raw eggs are digested in 1 1 / 2 to 2 hours; hard boiled or fried in 3 1 / 2 hours. Keratin is altogether indigestible. Elastin changes to elastoses. Collagen is converted by the gastric juice into gelatin. Gelatin is easily oxidized, and hence is a tissue-saver, though not a tissue former. It is particularly useful for young children and invalids; 100 gm. gelatin 36 gm. albumin. Animal fats are more easily digested and absorbed than vegetable fats. Fats promote the flow of bile and pancreatic juice, but if in excess interfere with or inhibit the gastric se- cretion. VEGETABLE FOODS. Bread is made from cereal flour and water, usually leavened by means of yeast. Wheat flour contains about 15 per cent, of water, 8 to 12 per cent, of gluten, and 60 to 70 per cent, starch; also sugar, dextrin, fat, and salts. The protein pirin- ciples are in the bran or cortic portion. White bread is, how- ever, more digestible than that made from the whole wheat. Too fresh or poorly baked bread forms a putty-like, glutinous mass in the stomach, on which the gastric juice can have little effect. Oats are especially rich in fats (5.14 per cent.), maize ranking next and rice lowest. Potatoes contain about 20 per cent, of starch. The K salts are just beneath the skin. Eice contains 75 per cent, of starch. Carrots possess considerable iron. Beans, pease, and lentils contain about 25 per cent, of protein (legumin) and over 50 per cent, of starch. These legumes and garden vegetables are apt to ferment in the bowels, owing to the large proportion FOOD AND DIET. 409 of water and cellulose they contain. For the same reason green vegetables must be used quickly after gathering. Nuts are rich in fat (pea-nuts, 46 per cent.) and are hence very nutritious, but must be well masticated. The organic acids of ripe fruits exist therein chiefly as alkaline salts. Fruit-acids stimulate digestion, and the cellulose, sugar, and water of fruits help constipation, for which purpose they are best taken before breakfast. Apples contain considerable phosphates and are di- gested in 1 1 / 2 hours. The volatile oils and oleoresins of condiments increase the flavor of foods and stimulate absorption and the flow of secre- tions, but must be used moderately, lest they irritate the mu- cous membrane. Eice, barley, and tapioca remain in the stomach about 2 hours; legumes and potatoes, 2 1 / 2 hours; white bread, 3 hours; brown bread, 4 hours. The stomach should be empty of all food in 6 hours after a meal. COOKING. To boil or stew meat properly the water must be boiling when the meat is put in, then be reduced in a few minutes to 160 or 170 F. and kept so till the meat is tender: that is, the tendons and fibrous tissues gelatinized. In this way the albumin and globulin at the surface coagulate, preventing loss of juices. The reverse process should be followed in making broths; the addition of salt helps to extract myosin. Vege- tables are better steamed than boiled, in order to retain their special virtues. Digestion of carbohydrates is aided chiefly by hydration of starches. For frying purposes the oil or fat should be boiling when the dough is put in. Otherwise the paste becomes saturated with grease and very difficult of digestion. Boasting is best done in the open air, where the meat be- comes more savory, digestible, and nutritious. Broiling, or grilling, and baking are modes of roasting. In baking bread the glucose produced from the starch of the flour is fermented by yeast into alcohol and C0 2 , which causes the dough to rise, and on heating the loaf continues to expand until the gluten is coagulated and the bread sets in a vesiculated mass. The alcohol escapes into the air. The crust is most digestible, being composed mainly of dextrin. Bread becomes sour from lactic and butyric acids when fermentation is allowed to go too far (alum prevents). A loaf of bread is not sterilized throughout by baking. 410 PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY. BEVERAGES. Dilute alcoholic liquors increase the flow of gastric juice and are rapidly absorbed. They are not tissue-builders, but tissue-savers, as shown by decrease of urea, being burned in the capillaries into C0 2 and H 2 to the extent of 1 1 / 2 or 2 oz. daily; 1 gm. alcohol = 0.071 calorie. Hence they are of service in some fevers. Alcoholics do not, however, give real strength. When used continually they probably combine with the nervous tissue of the brain, interfering with proper metab- olism and predisposing to disease. The excessive use of malt TABLE OF CALOKIFIC VALUES. (AFTER FEANKLAND AND JURGENSEN. CALORIFIC VALUE OF 100 GRAMS IN CALORIES. Apples 66.00 Arrowroot 391.20 Asparagus 18.50 Bean-soup 193.00 Boiled beef 209.00 Broiled beef 213 60 Raw beef 118.95 Beef-fat 906.90 Lean beef 156.70 Bread-crumbs 223.10 Butter 814.00 Buttermilk 41.56 Cabbage 43.40 Cakes 374.00 Cane-sugar 334.80 Carp 93.00 Carrots 41.00 Chicken-breast 106.40 Cheshire cheese 464.70 Codliver-oil 910.70 Cream 214.70 Hard-boiled egg 238.30 Yelk of egg 342.30 White of egg 67.10 Flour 393.60 Flounder 100.60 Macaroni 352.60 Mackerel 178.90 Milk 66.20 Skim-milk 39.61 Oatmeal 400.40 Omelet 236.70 Pea-meal 393.60 Potatoes 101.30 Pigeon 99.70 Green pease 318.00 Salmon 133.30 Ground rice 318.30 Trout . . . 106.40 Veal cutlets (raw) . . " " (broiled) . Wheat bread . . " (toasted) Whiting . 142.45 . 230.50 . 281.00 . 258.80 . 90.40 Zwieback . 357.80 liquors leads to the putting on of fat, from imperfect oxidation and elimination chiefly. The alkaloidal beverages tea, coffee (a cup contains 0.1 gm. of caffein), cocoa, chocolate, kola, and mate are nerve- stimulants and are closely related to uric acid. Hence their continued use is likely to excite migraine and other uricacidemic conditions. Tea and coffee should always be prepared by a few minutes' infusion with nearly boiling water, as prolonged boiling drives off the aromatic flavoring oil and causes the water to take up a bitter astringent, tannin, a radical opponent of eupepsia. In addition to caffein (0.8 per cent.), caffeotannic AUTOTOXEMIA. 411 acid, and the aromatic oil, coffee-berries contain fat, legumin, sugar, dextrin, vegetable acids, and mineral salts. On roasting, the sugar is changed to caramel and the aroma develops. Tea contains about 3 per cent, of thein and 13 per cent, of tannin (more in green than black), as well as dextrin, glucose, and a volatile oil. Cocoa is the most nourishing of these drinks, since it contains 50 per cent, of fat and 12 per cent, of proteins. Lemon-juice contains about .30 grains of citric acid per fluidounce. It is of special use in scurvy, which appears to be a mineral-acid intoxication due to an exclusive diet of meats or cereals. AUTOTOXEMIA. Autointoxication, or poisoning from within the body, is of great practical importance in the causation of various dis- eased conditions. The agents giving rise to autointoxication may be either pathologic chemic compounds or physiologic products in excess of normal limits. The general rule is that the waste-products of any organism are deleterious to it and may cause death, sometimes suddenly, when reabsorbed in suffi- cient amount. The toxic endogenous substances giving rise to autotoxemia include the fatty acids (beta-oxybutyric causes diabetic coma), aromatic phenols (intestinal autointoxication), tyrosin (hepatic insufficiency), purin bases (uricacidemia, migraine, and gout; guanin from cancerous degeneration causes coma), diamins (putrescin and cadaverin in gangrene and carcinoma); mucin in myxedema; neurin in Addison's disease; the amins (especially trimethylamin), aceton, special alkaloids, and leucomains, and the toxins generated by the colon bacillus, which is a constant habitant of the bowel. The etiologic classification of Albu is as follows: Arrest of organic function (myxedema, pancreatic diabetes, Addison's disease, acute yellow atrophy); anomalies of general metab- olism (gout, oxaluria, diabetes); retention of physiologic meta- bolic products (uremia or potassemia, eclampsia, cholemia, as- phyxia, extensive burns); overproduction of physiologic and pathologic products (overwork, diacetemia, ammonemia, cysti- nuria, etc.); decomposition of food-substances arising from maldigestion. The last class is most common, and is usually accompanied by constipation, indicanuria, and neurasthenic symptoms. Lithemia, or biliousness, is, generally speaking, the mani- festation of an overworked and long-suffering liver. The thy- 412 PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY. roid gland is involved in myxedema, cretinism,, cachexia stru- mipriva, and possibly exophthalmic goiter; the pancreas in dia- betes mellitus; the liver in jaundice or cholemia, lithemia, acute yellow atrophy, and icterus gravis; the kidneys in uremia and eclampsia; the adrenals in Addison's disease; the lungs in C0 2 poisoning from, interference with respiration; the gastro- intestinal tract in the depressed nervous conditions accompany- ing constipation, indicanuria, and oxaluria; the skin in the phenomena following severe burns of large surfaces; and the pituitary gland perhaps in acromegaly. The manifestations of autotoxemia in any given case are usually manifold, and not confined to one organ. Nervous symptoms are the most frequent, and comprise headache, ver- tigo, syncope, irritability, insomnia, hypochondria, stupor, coma, delirium, spasms or convulsions, paralysis, melancholia, and mania; polymyositis has been noted in a few instances. Com- mon cardiac symptoms are tachycardia, bradycardia, and arhyth- mia. The breathing may be stertorous or of the Cheyne-Stokes type. The temperature may be pyretic or subnormal, usually the first. Digestive symptoms include anorexia, nausea, vomit- ing, eructations, diarrhea, constipation, and colic. Toxemic disturbances of the urinary tract are manifested by albuminuria, hematuria, hemoglobinuria, choluria, acetonuria, diaceturia, and oxaluria. The skin may be anemic, jaundiced, or bronzed, and not seldom shows an erythematous eruption. Cachexias are frequent, particularly those of cancer, diabetes, chlorosis, leukemia, pernicious anemia, and the uric-acid diathesis. In- fantile rickets, purpura, scurvy, and pernicious anemia are often of autotoxemic origin. Chlorosis is said to be a sequel of copremia. INFECTION AND IMMUNITY. Most infectious diseases are known to be caused by the presence in the body of specific bacteria, which generate soluble poisonous bases, or toxins, that act as the direct cause of all the morbid symptoms. The term intoxication is applied when infectious microbes remain localized and only their toxic products enter the system. A certain bacterium may produce one or more toxins. Thus, the tetanus bacillus is responsible for four distinct toxins: tetanin, tetanospasmin, tetanolysin, and one unnamed. The relative toxicity of toxins in general is enormous; the diphtheritic toxin can produce lethal results in a living being 20,000,000 times its own weight. Tetanus toxin is 300 times as toxic as strychnin. The incubation period of an infectious disease is the period during which sufficient INFECTION AND IMMUNITY. 413 toxins are being formed to produce an appreciable constitu- tional effect. When diphtheria toxin is injected into a susceptible ani- mal,, as the horse, in gradually increasing doses, the said animal acquires a marked tolerance to the poison, so that an amount can finally be injected which at first would have proved quickly fatal. The serum of the animal's blood also acquires the prop- erty of protecting other animals against diphtheria when in- jected subcutaneously in sufficient dose. Such serum when concentrated is known as antitoxin, and is standardized by physiologic tests against a given quantity of toxin: both being injected at the same time into guinea-pigs. A normal anti- toxic unit is equivalent to 1 c.c. of normal serum, and will counteract 100 doses of toxin fatal to the guinea-pig. According to the Ehrlich theory of immunity, the presence of toxins in the blood stimulates the protoplasm of the leuco- cytes and the fixed tissues to an intramolecular migration of atoms to a more stable position. In this change are thrown out certain side-chains, or receptors, which have a particular destructive affinity for the given toxin and combine with and neutralize it. The molecules are not broken apart if the stimu- lation is slight, but protoplasmic resistance to the toxins is in- creased, as exemplified by vaccination. Under increased stim- ulus by the toxins myriads of these side-chains are liberated into the serum, giving it antitoxic properties, and constituting the more or less perfect active artificial immunity observed after one attack of a contagious disease. It is claimed that the amount of antitoxin set free can be augmented by the admin- istration of agents (pilocarpin) which stimulate cell-activity. Antitoxins may also be formed by the stimulating action of non-bacterial proteins (ricin, abrin). If, on the other hand, as in malignant cases, the toxin is overwhelming in force and amount, reaction is paralyzed, no side-chains are evolved, and the patient quickly succumbs. Passive immunity is that conferred by the injection of anti- toxins (diphtheria, tetanus, antistreptococcic, etc.), and is of much snorter duration than active immunity, since it is not re-enforced by fresh supplies from the cells and is gradually eliminated. The natural immunity which some persons and animals exhibit toward certain infections is explained on the entire absence of receptor formation and hence of combination with the toxins; in other words, the toxins do no harm because the protoplasm is not affected by them. It is further possible for a subject to be susceptible to the toxins of a disease when 414 PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY. directly injected and yet not amenable to ordinary inoculation by the germs of the disease, since the latter may not thrive in their environment with sufficient vigor to produce toxins in any quantity. Snake-venoms belong to the class of toxalbumins, and the protective and curative action of antivenene is probably a bio- chemic reaction analogous to that of antitoxins. It is a curious fact that venom when taken by the stomach protects against snake-bites, and the same is true of antivenene, but antitoxins are ordinarily best given hypodermically. Vaughan believes that toxins and antitoxins are nucleins, neutralizing each other chemically. Chemically speaking, tubercle bacilli consist of protoplasm inclosed within a waxy capsule. The toxic products of the life- processes of tubercle bacilli include a systemic poison, a fever- producing agent, and a necrotic. Tuberculin (the old T. 0., not T. R.) is a 4- to 7-per-cent. glycerin extract prepared from old, concentrated culture-media of tubercle bacilli. It contains salts, pepton, albumose, and other undefined proteins, one of which is a fever-producing toxin, and is used for diagnostic pur- poses in the dose of 1 / 2 or 1 mg. HEMOLYSINS. It has been discovered that the serum of one animal in- jected with the blood of another becomes toxic for the animal whose blood was injected, agglutinating and dissolving the red corpuscles of the blood. Such toxic substances, when produced by the injection of heterologous blood, are termed heterolysins. When the injections are in the same species isolysins are formed. Autolysins have so far not been produced. The serum of many animals is naturally cytotoxic and hemolytic, and the same is true of snake-venoms. Repeated injections in increas- ing dosage lead to the development of an antitoxic resistance to the poisons. Certain toxins (tetanolysin) contain two sets of molecules, one binding the antitoxins (haptophorous) and one producing hemolysis (toxophorous). Leucocytolysins are similar in action to hemolysins, dissolving the white blood-cells, however, without previous agglutination. Various theories of cytolysis have been proposed. One is that in immune serums there are two distinct substances, namely: the specific immune or anti- body (globulolytic and bacteriolytic), which is not de- stroyed by heat; and the non-specific alexin or complement, which is destroyed at 50 to 60 and which exists preformed in all blood. In hemolysis it is claimed that the anti-body is INFECTION AND IMMUNITY. 415 bound by the stroma of the red corpuscles or perhaps links the alexin to the cells. Another explanation of hemolysis by im- mune serums is through a sudden disturbance of osmotic equi- librium. Anticytotoxins is the term applied to substances that neu- tralize hemolytic serums. They are produced, in a similar way to antitoxins, by injecting hemolytic serums in increasing doses into susceptible animals. They seem to include both anti- alexins and anti-immune bodies. Various other toxic and antitoxic substances such as epi- theliolysin, spermotoxin, and nephrolytic serum are developed by the natural resistance of the cells to outside influences. It is possible that in some cases sterility depends on the presence of spermotoxic substances in woman's blood. BACTERIOLYSINS. Bacteriolysins are complex substances composed of a pep- tonizing ferment and a bacterial derivative. They have a di- gestive and antibacterial action, but no effect on toxins, which they set free, sometimes aggravating the condition. Destruction of bacteria may be due to plasmolysis or plas- moptysis (spewing out of cell-contents), depending on osmotic disturbances. Thus the diplococcoid form of colon bacilli said to be found in cirrhotic livers and the accompanying ascitic fluid are perhaps degenerating forms due to plasmolysis. These dead bacilli and bacillary fragments tend to take up iron, form- ing pigment-granules. Bacteriolysins may further be produced by the digestion of bacteria with peptonizing ferments. These lysins are pptd. by acetic acid and dissolve again in alkaline water. AGGLUTINATION. This curious property, forming the basis of the Widal test for typhoid fever, appears to be due to the action of agglutinins of unknown origin, so changing the bacterial membrane as to render it sticky. The agglutinating property of serum is not destroyed by heating to 180. Its homologous nature is not characteristic, since typhoid bacilli are clumped by diphtheria antitoxin. The agglutination of blood-corpuscles in coagulation is most marked in pneumonia, rheumatism, erysipelas, and ty- phoid. Owing to the firmness of the clot in these cases, the buffy coat is unusually distinct. 416 PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY. QUESTIONS ON PHYSIOLOGIC AND PATHOLOGIC CHEMISTRY. 1. Why is saliva frothy and viscid? 2. What is the color of the stools in jaundice? 3. How detect starch in feces? Fat? Mucus? Casein? 4. Why does the sweat often smell sour in summer? 5. How does taking HC1 diminish the amount of NH 3 in the urine? 6. What effect does muscular exertion have on the alkalinity of the blood? 7. How does (NH 4 ) 2 C 2 O 4 , added to freshly drawn blood, prevent, its coagulation? 8. Why does a sip of vinegar cause pain in mumps? 9. What causes the film on the surface of saliva on standing? 10. How does deficient motility interfere with stomach-digestion?" 11. Why not feed a young baby crackers? 12. Why do we need to add salt to our food? 13. How detect with certainty the presence of saliva in the stomach- contents ? 14. Why is whole-wheat bread more nutritious and less digestible than white bread? 15. Why are sterilized milk and artificial infant-foods likely to- produce rickets and scurvy? 16. Why is it best to boil potatoes in their skins? 17. What kind of diet is best for hypochlorhydria? 18. Why is toast more digestible than untoasted bread? 19. Why must the blood be saline? Alkaline? 20. What chemic effects have fruits on blood and urine? 21. Explain the chemistry of infantile colic. 22. What chemic compounds are present in hair? 23. Why do the nursing mother's teeth often decay rapidly? 24. Write formulas for xanthin, theobromin, caffein (them), and uric acid. 25. Gall-stones are most frequent in fat, elderly women. Why? 26. To reduce obesity what kinds of food should be avoided? 27. Why is fracture in children often of the "green stick" type? 28. What chemic changes accompany muscular contractions? 29. What is the chemistry of atheroma? 30. What is the difference in composition between blood- serum and plasma ? 31. What element is indicated medicinally in anemic conditions? 32. What is the color of a person's lips poisoned by "blowing out the gas"? 33. Explain the symptoms of "heart-burn" and "water-brash." 34. Why do milk and other proteid foods give relief in hyperchlor- hydria ? 35. State the chemic distinctions between gastric ulcer and gastric cancer. 36. What hydrocarbon is found in the body? What alcohol? What ethers ? 37. Compare the composition of human and bovine milk. 38. What are the chemic differences between whey and butter-milk ? 39. How does chyle differ from lymph? 40. Give some chemic reasons for the symptoms of Addison's disease. 41. On what various factors does diabetes mellitus depend? QUESTIONS. 417 42. How distinguish with certainty blood in the stools from other coloring matter? 43. Why is yellow sputum usually more liquid than white? 44. What are the chief distinctions between exudates and transu- dates? 45. How do potatoes cure scurvy? 46. If 1 gm. urea = 3 gm. albumin, how much protein food does a laboring man weighing 140 pounds require daily? 47. What advantages have cheese and pulses over meats in uric- acid cases? 48. Name ten foods especially good for students, and give reasons. 49. Define internal respiration. 50. What substances act as fuel foods? 51. What is the office, chemically speaking, of digestion? 52. Why is it sometimes advisable to prescribe medicines with ginger, capsicum, nutmeg, and other spices? 53. Explain from the physic standpoint the removal of dropsies by diuretics. 54. How may an attack of uremia be pptd. by the free use of digi- talis after tapping an ascites? 55. Distinguish between active immunity, passive immunity, vac- cination, and natural immunity. 56. W 7 hy do fats generate more heat in the body than carbohy- drates or proteins? 57. Why is the lowest daily range of normal body-temperature in the early morning? 58. Make out a diet-table for 3500 calories, using roast beef, wheat bread, potatoes, milk, and butter. 59. Why should diphtheria antitoxin be given as early as possible? 60. How does the addition of borax or Na 2 CO 3 delay the souring of milk? 61. Why do infants become anemic when limited too long to a milk diet? 27 CLINIC CHEMISTRY. GASTRIC JUICE. FOE clinic purposes the stomach-contents are usually drawn with the soft stomach-tube an hour after taking Ewald's test-breakfast. This consists of a one-ounce dry roll or two pieces of toast without butter, and 2 / 3 P in t (500 c.c. better) of warm water or weak tea without milk or sugar. The double test-meal of Hemmeter consists of a full meal at 8 A.M.; Ewald's test-meal at 12 M.; withdrawal of stomach-contents and exami- nation at 1 P.M. Disappearance of the entire breakfast points to normal digestion; absence of all proteids, with presence of considerable carbohydrates = hyperchlorhydria; absence of all carbohydrates, with presence of some beef and egg = hypo- chlorhydria or anacidity; presence of entire meal, with the milk perhaps all uncurdled = achlorhydria and absence of ferments and glandular atrophy. The quantity of gastric juice obtained in this way is nor- mally about 40 c.c.; more than 60 c.c. or less than 20 c.c. is pathologic. The former condition points to dilation and motor insufficiency; the latter, to too rapid emptying of the viscus. The liquid should be filtered at once and examined as soon as possible. The reaction is tested with litmus-paper, and is normally frankly acid. The presence of free acids is shown by congo-red paper, which turns deep blue with 1 part in 50,000 of mineral acid; violet, with organic acids. Tropeolin 00 in aqueous solu- tion is a dark yellow-red or brown fluid, changed to pink by 1 to 4000 of free HC1, giving a bluish residue on drying; to a straw color by acid salts. Benzopurpurin (6 B) paper is turned an intense dark brown by mineral acids. A 1 to 2000 aqueous methyl-violet solution added to the specimen yields a copper- blue color with HC1; a violet-blue with organic acids. Free HC1 can also be shown by the addition of 3 or 4 drops of a 5-per-cent. alcoholic solution of dimethyl-amido- azobenzol, which gives a pink color if this acid is present in the free state, while a yellow color indicates its absence. Giinz- burg's reagent is prepared by dissolving 1 gm. vanillin and 2 gm. phloroglucin in 100 c.c. of alcohol. The solution to be tested is placed in an evaporating dish, 2 or 3 drops of the (418) GASTRIC JUICE. 419 reagent added, and the mixture evaporated to dryness just below the b.p. on the water-bath or over a small flame. A purple or pink-red color shows free HCL Boas's reagent is prepared by dissolving 3 gm. of cane-sugar, 10 gm. of resorcin, and 3 c.c. of alcohol in 100 c.c. of distilled water. To the specimen in a porcelain dish add 2 or 3 drops of the reagent and evaporate as above, getting with free HC1 a vermilion line at the edge of the dried fluid, fading to reddish brown on cooling. Experiment. Make a 0.25-per-cent., a 0.05-per-cent., and a 0.01- per-cent. solution of HC1. Perform each of the three tests described above with 1 c.c. of each of these three solutions, and determine which test is most delicate. Uffelmann's reagent for lactic acid is prepared by adding a drop of dilute neutral Fe 2 Cl 6 to 10 c.c. of 2.5-per-cent. car- bolic acid solution. The resulting amethyst color is discharged by mineral acids, but lactic acid changes it to a straw color (butyric brownish), best noted by comparing with another tube containing the same amount of iron in the same volume of water. The reaction is interfered with by much free HC1 and by the presence of cane-sugar or alcohol. To make the test positive the lactic acid must be isolated by extracting several times with ether, which is distilled off and the residue dissolved in water for testing. Test for Lactic Acid in the Gastric Juice (J. P. Arnold). Solu- tion 1 = 0.2 c.c. of saturated alcoholic solution of gentian violet in 500 c.c. distilled water. Solution 2 = 5 c.c. of solution of ferric chlorid (U. S. P.) in 20 c.c. of distilled water. In a small porcelain capsule mix 1 c.c. of first solution and 1 m. of second,, forming a bluish-violet liquid. To this liquid add drop by drop the filtered gastric contents, when if lactic acid is present the color changes to green or greenish yellow. The reaction is distinct with 1 drop of 1 to 5000 solution of the acid. Acetic and butyric acids are recognized by their distinctive odors. Acetic acid also gives a red ppt. with dilute Fe 2 Cl 6 ; butyric, a tawny red. Alcohol, rarely present from yeast-fermentation, is de- tected by its odor or by the iodoform test. Test for Pepsin. To 10 c.c. of the gastric juice add a flake of co- agulated white of egg: best prepared by gradually pouring a dilute solution of egg-albumin, with constant stirring, into boiling water. Set aside at 40 for 2 or 3 hours; if not dissolved *n this time, leave over night at same temperature. If free HC1 is absent add an equal volume of 0.5 per cent. HC1 before putting in the albumin. A failure to dissolve and to form albumoses (recognized by biuret test) indicates the absence of pepsin. A few shreds of washed fibrin should dissolve in Y 2 to 1 hour; the disk of egg-albumin in 10 or 12 hours at the latest. 420 CLINIC CHEMISTRY. Test for Rennin. Neutralize 5 c.c. of filtered gastric juice with decinormal alkali solution, and an equal volume of carefully neutralized milk, and keep at body-temperature. Coagulation should take place in 10 or 15 minutes if chymosin is present. As a matter of fact, the gastric ferments are practically always present when there is free HC1 in the gastric juice. The Oppler-Boas bacilli are unusually long, non-motile, club-shaped bacilli, present in large numbers in gastric cancer. To detect them dry and fix a drop of the stomach-contents on a cover-glass and place for 3 minutes in very dilute gentian- violet solution, washing out in water and mounting in Canada balsam. Yeast-cells and sarcinaB are usually found in fermenta- tive conditions. PRACTICAL QUANTITATIVE ANALYSIS OF GASTRIC JUICE. In Toepfer's method four reagents are required: 1. Deci- normal NaHO. 2. A 1-per-cent. alcoholic solution of phenol- phthalein, to indicate total acidity. 3. A 1-per-cent. aqueous solution of sodium-alizarin sulphonate, to indicate all acids except loosely combined HC1. 4. A 0.5-per-cent. alcoholic solu- tion of dimethyl-amido-azobenzol, to indicate free HC1 only. Put 10 c.c. of filtered gastric juice into each of three beak- ers. To the first add 1 or 2 drops of phenol-phthalein; then run in the decinormal solution till a deep-red color is produced which no longer increases in intensity. To the second add 3 or 4 drops of the alizarin solution, and titrate with the decinormal alkali till the first pure violet color is reached. To the third beaker add 3 or 4 drops of dimethyl-amido-azobenzol, and if a red color is produced run in the decinormal alkali till the red just disappears and the fluid becomes yellow. The number of c.c. required for the first beaker (a) repre- sents the total acidity; for the second beaker (1)), all acids except loosely combined HC1. Hence, deducting & from a leaves the combined HC1. The number of c.c. needed to change the color in the third beaker (c) represents free HC1. Hence, de- ducting c from & leaves the organic acids: chiefly or wholly lactic. The amount in grams of each of these five findings, reck- oned as HC1, is obtained by multiplying the number of c.c. required in each instance by the factor 0.003637 (no. of c.c. of lactic acid by 0.009); or the percentage (when 10 c.c. of juice are used) is found by multiplying by 0.03637. MILK. 421 Quantitative Test for Lactic Acid (Strauss). A separating funnel graduated to 5 c.e. below and 25 c.c. above is filled to the lower mark with gastric juice, and ether is added to the upper mark. The funnel is corked, well shaken, allowed to stand till the fluids separate, and the liquids allowed to run out to the lower mark. Distilled water is now added to the upper mark, and the mixture treated with 2 drops of a 1 to 10 solution of tincture of chlorid of iron. On shaking the mixture an intense-green color is produced if lactic acid is present to the extent of 1 to 1000 or more; pale green if between 0.5 and 1 per 1000. Test for Gastric Absorption. Let the patient take a capsule con- taining 5 grains of KI along with 100 c.c. of water. The salt should be found in the saliva within 15 minutes, as shown by means of starch-paper wet with saliva, then touched with a drop of HNO 2 . Free I is liberated, giving with the starch a blue color. Test for Gastric Motility. 1. The oldest and most reliable method is that of Leube, which consists in washing out the stomach 6 to 7 hours after a full meal of meat, soup, and bread, or 2 Y 2 hours after Ewald's test-breakfast. Any residue found at this time denotes a lack of motor power. 2. Let patient take 10 grains of salol in capsules. The salol is broken up in the intestines and should appear in 40 to 75 minutes in the urine as salicyluric acid, as proved by filter-paper dipped in 10-per- cent. Fe 2 Cl solution giving a blue spot with a drop of the urine. If the reaction comes later than the time mentioned or if it lasts 30 hours or longer, the motile power is deficient. 3. Another method (Klemperer's) of estimating the motor function of the stomach is to wash the viscus thoroughly and then pour through the tube 100 c.c. of olive-oil, removing what remains 2 hours later by aspiration, at which time the residue should not exceed 20 to 40 c.c. The presence of food in the fasting stomach before break- fast indicates a high degree of submotility, usually accompanied by gastric dilation. The form and location of the stomach is determined by palpation and percussion. For these maneuvers the organ should be distended with C0 2 , generated by administering, each in 250 c.c. of water, a teaspoonful of tartaric acid followed by the same quantity of sodium bicarbonate. This procedure is also useful in palpating tumors. MILK. Mothers' milk taken to be tested should be either a spec- imen from the whole breastful or a sample taken about mid- way in nursing. The milk, whether human or bovine, should be well mixed by shaking before the quantitative tests are applied. It should be as fresh as possible. The quantity for each test is best measured with a graduated pipet. The reaction of milk is ascertained by means of both red and blue litmus-paper. Its color and consistence should be 422 CLINIC CHEMISTRY. carefully noted. The whiter and more opaque, the richer the milk is, unless adulterated. The specific gravity may he determined hy means of a cylinder and a correct hydrometer or Quevenne's lactodensime- ter, or more accurately with the picnometer or the lactometer. This latter instrument is so graded that on its scale repre- sents a sp. gr. of 1, that of water, while 100 is equivalent to a sp. gr. of 1+029, the normal minimum of good milk, and 120 to 1.034. Genuine cows' milk usually ranges from 105 to 120. Skim-milk is heavier. Watered milk is of low specific gravity: "below 100 if sufficient water has heen added. Natural rich Jersey milk is -generally heavy. Any whole milk that stands above 1.033 is nearly certain to have been skimmed, while that below 1.029 is nearly always watered. In making corrections for temperature one hydrometer degree approxi- mately may be subtracted for each 10 F. below the standard of the hydrometer, or one degree added for each 10 F. above this standard. The percentage of cream by volume is ascertained by means of the creamometer, which is simply a small cylinder graded in hundredths and kept closed with a glass stopper. The per- centage of cream is quite variable as to the amount of fat, de- pending on dilution, agitation, temperature, and other factors. Specimens that contain the least fat may yield the most cream, and a milk that has been watered will in a few hours separate a thicker layer of cream than if it had not been watered. The amount of cream that separates in twenty-four hours is from 10 to 12 per cent, in ordinary, and 15 to 20 per cent, in good milk. Less than 10 per cent, of cream with a sp. gr. above 1.033 denotes skimming. Less than 20 per cent, with a sp. gr. below 1.029 shows that the milk has been watered. Determination of Total Solids. Weigh into a tared platinum dish or watch-glass 5 c.c. of milk, evaporate on the water-bath to dryness (about three hours), then transfer to the water- or air- oven at 100 C. until it ceases to lose in weight (about three hours), cool in desiccator, and weigh. Determination of Ash. The mineral residue is estimated by careful ignition of the total residue at a dull-red heat until the organic matter is burned off and the sediment becomes gray-white in color and ceases to lose in weight. Adulteration with chalk, borax, etc., increases both the total solids and the ash (above 1 per cent.). Phosphates, chlorids, and sulphates may be separated by the ordinary tests. Determination of Fat. In the Werner-Schmid method 10 c.c. of milk are mixed with 10 c.c. of strong HC1 in a long test-tube with a capacity of 50 c.c. The mixture is brought to a boil (till the liquid turns deep brown, but not black) ; then cooled, 30 c.c. of ether added, and the tube corked and shaken well. As soon as the ether separates, a wash-bottle cork-stopper (lower end of exit tube with a short curve MILK. 423 and opening just above the line of separation) is inserted and the ether blown oil' into a tared flask. Ten c.c. more of ether are added twice, and blown off as before. The ether is now distilled from the flask and the fat-residue dried in the water-oven and weighed. Another simple method of estimating the milk-fat is by treating the total solids with excess of benzin four times, boiling down on the water-bath each time to half, and decanting. The loss of weight in the residue equals the fat. Since the opacity of milk varies with the amount of contained fat, pioscopic methods are of service in estimating this constituent. Feser's lactoscope consists of a glass cylinder constricted at the lower closed end, in the axis of which projects a small plug of white glass marked with a few horizontal black lines. Four c.c. of milk are introduced into the instrument, concealing the black lines. Pure water is then added, with frequent shaking, until the lines become visible. The surface-level Fig. 51. Feser's Lactoscope. of the liquid indicates the percentage of fat in the specimen, as shown by the graduation on the vessel. With a little experience the readings can be made accurate within 0.25 per cent. Opacity due to suspended chalk or starch is differentiated with the microscope. The official method for detection of fat in milk is that of Adams. Ten c.c. of milk is absorbed by a coiled strip of fat-free bibulous paper, about 2 by 24 inches in size and tied with a thread or wire. This is dried on a watch-glass in the water-oven for an hour or more, and then placed in the middle chamber of a Soxhlet extractor. The tared flask (150 c.c.) at the bottom, containing 75 c.c. of ether, is heated cautiously on the water-bath. The ether-vapor, condensing in the upper part of the ap- paratus, flows back through the paper into the flask. After ten such siphon-washings, lasting one to one and one-half hours, the flask is de- tached and connected with a condenser and the ether distilled off. The fat-residue is dried in the air-oven at from 100 to 105, cooled, and weighed. 424: CLINIC CHEMISTRY. The centrifugal method of separating fat is very convenient, and gives results accurate to 1 / 5 of 1 per cent. To 5 c.c. of milk is added, with shaking, 1 c.c. of a mixture of 13 volumes of wood alcohol, 37 vol- umes of amyl alcohol, and 50 volumes of HCL, and then the tube or bottle is filled up with about 5 c.c. of strong H 2 S0 4 , well shaken, and revolved for three minutes, when the percentage of fat can be read off directly. Estimation of Sugar. This constituent is fairly constant in un- watered milk. Dilute 10 c.c. of milk to 200 c.c., add acetic acid gradually till coagulation takes place, pass CO 2 into the liquid for fifteen minutes, let stand, and settle. Filter, wash residue, and coagulate lactalbumin and globulin in filtrate by boiling. Filter again and estimate lactose in filtrate by means of Purdy's method (see "Urine") or by Fehling's solu- tion, 10 c.c. of which is decomposed by 0.0676 gm. lactose. Another method for estimating sugar of milk is to acidulate with HC1, boil, filter, wash, and then boil filtrate again for an hour or so to hydrolyze all the lactose to glucose, which may then be estimated with Purdy's solution. Estimation of Proteids. Casein can be pptd. by diluting 10 c.c. of milk with 50 c.c. of water, warming on the water-bath to 40, adding 2.5 c.c. of 10-per-cent. alum solution, and stirring thoroughly. After fifteen minutes the finely flocculent ppt. should be removed by filtration, washed, and determined by the Kjeldahl method for N (see "Urine"), the result being multiplied by 6.37 to obtain the weight of casein. To the filtrate from the alum ppt. add 10 c.c. of Almens's tannin solution (10 gm. of tannin, 10 c.c. of 25-per-cent. acetic acid, 90 c.c. of alcohol, and 100 c.c. of water). This ppts. albumin and globulin, which may be estimated in just the same way as casein. The total N can also be estimated by placing 10 c.c. of milk in a Kjeldahl flask, adding 15 c.c. of H 2 S0 4 , and testing as above. These proteins are usually determined by difference. They may also be pptd. with tannin. The ppt. is dried and washed with 1 part of alcohol and 3 parts of ether till the washings show no trace of tannin with iron solution, then dried and weighed. In the Woodward centrifugal method for proteins- 5 c.c. of milk is placed in each of two milk-burets and kept at 95 to 100 F. for 18 to 24 hours, then cooled in water. The milk-serum is now drawn off, mixed with 10 c.c. of Esbach's solution (see "Urine"), and centrifugated until the reading is constant. The volumetric percentage equals the per- centage by weight of total proteins. Short Methods. A number of formulas have been devised by ex- periment to save time and trouble in milk analysis. When any two of the three data, sp. gr. (G), fat (F), and total solids (T) are known, the third can be calculated by the following formulas: T F + 0.2186 G (last two figures) 0.859 F = 0.859 T 0.2186 G (last two figures) For poor skim-milk, when ^ exceeds 2.5, this modified formula should be employed: F = 0.859 T 0.2186 G 0.05 ( 2.5) The following is a formula to determine the amount of skimming: URINE. 425 S (solids not fat) F X */9 = x, or amount of fat removed. The degree of watering is estimated by this formula: Solids not fat X 100 mNature lyDrJ". Voyel VOGEL'S SCALE OF URINE TINTS. URINE. 427 Many drugs affect the color of the urine. It is colored green by saffron or salicylic acid; orange by chrysophanic acid or santonin (carmin, if alkaline); brown by chelidonium or senna (blood-red,, if alkaline); smoky brown or black from tar, salol, gallic acid, resorcin, uva ursi, or naphtalin; reddish from logwood (alkaline, violet) or fuchsin; bright yellow from picric acid; blue from methylene blue (often greenish) or methyl violet. Pathologically the urine is very pale in hysteria, dread, and anxiety; after convulsions, and in diabetes insipidus. In diabetes mellitus it is pale and opalescent, often with a green- ish tinge if there is much sugar. It is also pale in chronic in- terstitial nephritis, amyloid disease, hydronephrosis, anemia, chlorosis, and convalescence from acute affections. Milky urine is noted in pyuria (pyelitis, cystitis, gonorrhea), phosphaturia, and chyluria. The urine is generally high-colored in renal congestions, acute nephritis, and acute febrile and inflammatory diseases. It is rendered darker by concentration from any cause (diar- rhea, vomiting, sweating freely) and in melancholia. In hema- turia (cancer, sarcoma, or trauma) the blood is red or smoky; in hematinuria it is smoky brown or even black; in hemoglobi- nuria (malaria, scarlet fever, KC10 3 poisoning) it is pink or even porter-colored. Carbolic acid poisoning renders the urine dark brown to greenish black, especially on standing, from oxi- dation of pyrocatechin; the same color is noted in poisoning by creasote, cresol, guaiacol, cyanids, or arsin. In sulphonal poisoning the urine is colored brown red, from hematopor- phyrin. Choluria, or the presence of bile, is marked by a bright- yellow to green-brown or porter color, with a yellow foam on shaking. It is dark yellow, nearly black, in pathologic uro- bilinuria and indicanuria. The normal yellow hue gradually turns black in melanuria and alkaptonuria; the change takes place at once on adding oxidizing agents, such as HN~0 3 or Fe 2 Cl 6 . A mixture of urates and phosphates or pus and phos- phates exhibits a dark-gray appearance. The urine is purple or pinkish in color, from excess of urates, in acute gout, rheumatism, and liver disorders (lithe- mia). It is rosy in chyluria with hematuria, due to filariasis. It rarely shows a dirty-blue or green scum in cholera, typhus, cystitis, or nephritis, from decomposition of excess of indican. In trional poisoning it shows a cherry tinge. In bacteriuria the urine is grayish and opalescent. 428 CLINIC CHEMISTRY. ODOR. The slightly aromatic odor of fresh urine is due to minute amounts of phenylic, taurylic, damolic, and damoluric acids and volatile ethers. The strong urinous odor of decomposed sam- ples is due to ammonium carbonate and sulphid. The more concentrated the urine, the stronger is its odor. On standing for some days (sooner in warm weather) it becomes ammoniacal and putrescent. Characteristic odors are imparted by the ingestion of asparagus, asafetida, cabbage, carbolic acid, cauliflower, copaiba, cubebs, garlic, parsnips, saffron, santal-oil, spices, Tolu, valerian, etc. Turpentine and terebene give a scent like violets. Urine which is pungent and ammoniacal when first passed is characteristic of chronic cystitis or paralytic retention. It is peculiarly putrid in pyelitis. The aroma is sweet and fruity or hay-like in diabetes mellitus, becoming alcoholic; in ace- tonuria it is like apples or chloroform. The smell is offensive, like stale fish, in bacteriuria. It is almost absent in obstructive retention, forming cysts. A fecal odor is a sign of a recto- vesic fistula or-abscess. The urine is fragrant, like sweet-brier, in cystinuria; but when the cystin decomposes it smells like sewer-gas. TRANSPARENCY. Normal urine is quite clear when freshly passed. On stand- ing a slight cloud of mucus and epithelia forms near the bottom in a few minutes; on cooling to near f.p. a "brick-dust" sedi- ment of acid urates is frequently seen, especially if the urine is scanty; it becomes dull and opaque from fission-fungi in twenty-four to forty-eight hours; alkaline fermentation is ac- companied by cloudiness, due to earthy and triple phosphates, ammonium urate, and bacteria. Diminished pigmentation tends to ppt. uric acid crystals. A temporary cloudiness occurs from excess of vegetable food-salts or from mental strain (fixed alka- line reaction). Permanent cloudiness, or "phosphaturia," de- pends on low acidity, with consequent precipitation of earthy phosphates, and is due to nervous debility or indigestion with hyperchlorhydria. The urine is often turbid in fevers from precipitation of urates (white, yellow, brown, or pink). Crystal- line sodium urate is occasionally observed in acute febrile diseases of children. A deposit of uric acid and urates within three or four hours takes place in disorders of the digestive apparatus; this precipitation takes place at once or nearly so in calculus. Early deposition of the acid also occurs in con- valescence from febrile complaints, particularly articular rheu- URINE. 429 matism; the middle period of chronic interstitial nephritis; chorea, diabetes, and enlarged spleen. Infarcts of uric acid are common in infants, who strain and cry out when passing water; there is then found a pink or yellowish sandy deposit on the diapers. The presence of a sediment of a normal ingredient is no indication whatever of excess or of the amount in any way; but rather of some change in the reaction or concentration of the urine. The following short list will aid in differentiating the most common forms of sediment and cloudiness: 1. Turbidity cleared by heat (below b.p.) or an alkaline hydrate = urates (acid varieties, pink, yellow, or fawn-colored; ammonium urate, white). 2. Not cleared by heat, but with acetic acid = phosphates (whitish). 3. Insoluble in acetic, but soluble in hydrochloric, acid = calcium oxalate (whitish, resembling cloud of mucus, and mixed with it; "envelope" microscopic crystals). 4. Cleared up by ammonium hydrate, but not by heat = cystin (greenish). 5. Intensified more or less by heat and acids: Blood: red, smoky, or chocolate brown; microscopic cor- puscles. Mucus: white and stringy; liquefied by liquor potassse. Pus: white and creamy; made gelatinous by liquor po- tassae. Semen or epithelia: both diagnosed only with the micro- scope. 6. Unaffected by heat, chemic agents, or filtration bac- teria (colon bacilli, bacterium, and micrococcus ureas; mold or yeast-plants, and specific germs). 7. Granular precipitate resembling Cayenne pepper (some- times brown or yellow and rarely white) = uric acid. 8. Milky appearance, most marked near top of fluid = fat or chyle (both cleared up by shaking with ether). CONSISTENCE. Normal urine is limpid and nearly aqueous. It is thick, viscid, and ammoniacal in chronic cystitis. In fibrinuria it gelatinizes on standing, forming a grayish coagulum insoluble in water, but dissolved by pepsin and 1-per-cent. HC1. In chyluria with fibrinuria the pink urine may coagulate before voiding. The presence of albumin, sugar, or bile gives rise to a persistent foam on shaking. 430 CLINIC CHEMISTRY. CHEMIC REACTION. The reaction of the urine is normally slightly acid (alkaline as it leaves the capsule) and due to NaH 2 P0 4 , which is derived from the Na 2 HP0 4 of the blood by reaction with carbonic, uric, hippuric, and sulphuric acids. The degree of acidity is esti- mated in the usual way with decinormal alkali, using litmus as an indicator. The mixture of acid and neutral phosphates in- terferes with the end-reaction, making the findings a trifle high. The total acidity corresponds to 2 to 4 gm. of oxalic acid. The urine is sometimes alkaline after meals, especially if much vegetable food has been taken, said alkalinity being due to the carbonates and bicarbonates of the alkali metals. It is occasionally amphoteric, from the presence of both acid and neutral phosphates. On standing acid urine often becomes more acid, from enzyme action of mucus on coloring matters, causing lactic and acetic acid fermentation; in four or five days (sooner if warm weather, or if feebly acid and of low density) it always under- goes ammoniacal fermentation from the action of the fission- fungi on urea: N 2 H 4 CO + 2H 2 = 2(NH 4 ) 2 C0 3 Urinary acidity is increased by excess of meat, .prolonged muscular exercise, and ingestion of saccharin and mineral or benzoic acids. Alkalinity (fixed) is favored by a vegetable diet, hot or cold baths, free perspiration, and alkaline hydrates or carbonates and salts of vegetable acids. The normal acidity is decreased after meals, often becoming neutral in three to five hours, rising again as the food passes into the intestines. Pathologically the urine is sharply acid in lithemia, gout, acute rheumatism, diabetes, pleurisy, pneumonia, and other in- flammations; also in starvation, scurvy, leukemia, and chronic interstitial nephritis. Its hyperacidity in gastric achlorhydria is due to free fatty acids (lipaciduria). Fixed alkalinity is distinguished by the fact that the red color of the litmus-paper is not restoied by drying. It is noted, with deposit of earthy phosphates ("phosphaturia"), in chlorosis, anemia, general debility, nervous dyspepsia, organic nervous diseases, resorption of alkaline transudates, atrophic gastritis, and when there is loss of gastric juice by fistula or vomiting. Much blood or pus in the urine also causes fixed alkalinity. The volatile alkalinity of ammoniacal urine is shown by the red color of litmus being restored on drying. It is observed in freshly passed urine, with deposit of earthy and triple phos- URINE. 431 phates, in chronic cystitis and in retention of urine due to para- plegia, myelitis, enlarged prostate, or urethral stricture. The normal digestive curve is always increased in gastro- succorrhea; it is absent in atrophic gastritis, severe chronic gas- tritis, and cancer of the stomach. DAILY QUANTITY. This ordinarily ranges from 1000 to 1200 c.c. for men; 900 to 1000 c.c. for women; and for children relatively more than for adults in proportion to body-weight. More is passed in the afternoon, less in the forenoon, and least at night; the maxi- mum is a few hours after meals. High altitudes and the sum- mer season decrease the quantity of urine. The quantity of urine is increased by cold and a moist atmosphere, nervous excitement, moderate exercise, liberal po- tations, and the use of diuretics, including alcohol and sugar. The quantity is decreased by vicarious action of the skin, bow- els, or lungs; by rest; and by fluid or dietary abstinence. Permanent polyuria is observed in both forms of diabetes and in chronic interstitial nephritis; also in amyloid kidney, cystic renal degeneration, renal tuberculosis, pyelitis, constipa- tion, cardiac hypertrophy, and in organic nervous lesions, espe- cially of medulla (sugar also present in about half the cases of hemorrhage). Temporary or paroxysmal polyuria is noted in hydro- nephrosis, alternating with periods of diminution; in conva- lescence from acute affections, particularly with resorption of serous effusions; also in hysteria (hydruria), excitement, and some cases of nervous debility, convulsions, chorea, and mi- graine. Oliguria is seen especially in acute and chronic diffuse nephritis and in renal congestion (increased quantity in first stage of active variety) from cantharides, turpentine, etc. Other causes of diminished urine are the fastigium and defer- vescence of acute fevers, diarrhea, dysentery, cholera, persistent vomiting, gastric dilation, pyloric stenosis, cardiac dilation and insufficiency, chronic lead poisoning, hepatic cirrhosis with dropsy, melancholia, emphysema, and chronic bronchitis. In renal calculus the amount of urine is temporarily diminished, with pain and frequent micturition, becoming copious when the obstruction is removed. Partial or complete suppression (anuria) is sometimes noted in acute and chronic nephritis, and following ether anes- thesia, reflex shock from operation (particularly genito-urinary), catheterization (urinary fever), internal injuries, severe hemor- 432 CLINIC CHEMISTRY. rhages, or strangulated bowel. Obstructive suppression is en- countered when the ureter is plugged by a calculus and the other kidney is absent or non-functionating; obstruction of ureters by a colon growth or by a tumor at the vesic orifices; and by irritation reflected to the kidneys from a diseased blad- der, enlarged prostate, or old stricture (this form is transient and may follow a debauch). Suppression is also noted in some cases of hysteria, puerperal eclampsia, the algid stage of cholera, grave fevers and inflammations, and toward the fatal end of renal and other diseases. In thrombosis of the renal vein anuria is preceded by the passage of blood and blood-casts. In obstructive suppression the urine is pale and watery, with no albumin or casts, as a rule. In non-obstructive suppression the urine is concentrated and is likely to contain albumin, blood, and casts. Eetention of urine in the bladder may be due to urethral obstruction or a paralyzed bladder, and is readily diag- nosed by percussion and catheterization. Saline diuretics act by increasing osmotic pressure of plasma, causing hydremic plethora and consequent rise of blood-pressure. SPECIFIC GRAVITY. This is determined by means of a urinometer and jar, or more exactly by the Westphal balance. The best urinometer is that of Squibb, with a spindle-shaped bulb and a fluted cylinder. When the temperature of the urine is not the same as the standard of the instrument, about 7 may be allowed for each degree above or below this standard. The normal sp. gr. of urine ranges from 1.015 to 1.025. In young infants it is often below 1.005. The sp. gr. varies inversely with the quantity, as a rule; hence, is higher in sum- mer than in winter. It is raised by excess of proteid foods or salts, active muscular exercise, and copious diaphoresis. It is lowered by fasting, chilling, nervous excitement, milk and vege- table diet, and the imbibition of much fluid. Pathologically the urine is of high sp. gr. in acute fevers and inflammations, melancholia, most cases of functional albu- minuria, acute diffuse nephritis, cyanotic renal induration, and markedly with polyuria in diabetes mellitus. A low sp. gr. is the rule in all forms of Bright's disease (with oliguria or polyuria) and renal insufficiency except the two above mentioned. A fall of density may precede uremic convulsions for several days. The density is also reduced in diabetes insipidus (may be 1.000 to 1.005), hysteria, anemia, chlorosis, and most chronic diseases attended with inanition; URINE. 433 serous exudations (dropsy or edema); after copious sweating, vomiting, or diarrhea; in convalescence from acute diseases, and toward the fatal end of acute maladies. A low sp. gr. with a high color is specially significant of the approach of death in chronic diseases. Generally speaking, decrease of sp. gr. without a corresponding increase of water is a bad sign. TOTAL SOLIDS. The average daily quantity of total solids in the male adult is about 70 gm., of which nearly V 2 is urea, V 5 NaCl, and 1 / 25 phosphates. In each 1000 c.c. of urine there are about 967 Fig. 53. Squibb's Urinometer. parts of water and 33 parts of solids, 2 / 3 being organic and V 3 inorganic. The total solids in gm. per 1000 c.c. can be calculated ap- proximately by multiplying the last two figures of the sp. gr. by 2 Y 3 ; this is called Haeser's coefficient. Another method to find the amount of solids in grains is to multiply the last two figures of the sp. gr. by the number of ounces of urine daily, then add to the product y M of itself. Ten per cent, should be deducted from the total solids for persons between 40 and 50; 20 per cent, between 50 and 60; 30 per cent, between 60 and 70; and 50 per cent, above 70. Deduct 1 / 3 from total average of solids in persons who have fasted for two or more days; for total rest deduct Y 10 . 434 CLINIC CHEMISTRY. NORMAL CONSTITUENTS. CHLORIDS. These are derived entirely from the chlorids of the food, chiefly NaCI, and amount to 10 to 16 gm. daily. The amount excreted also varies directly with the volume of urine. It is decreased by rest, increased by exercise. The digestive curve of chlorids corresponds closely with the curve of acidity. Pathologically an absolute increase is noted in diabetes insipidus, Bright's disease, after epileptic attacks, in the de- clining stage of dropsy (resorption), and after the crisis of acute fevers and inflammations (resorption); also in prurigo and in- termittent fever. An absolute decrease is observed before and up to the febrile crisis, particularly in pneumonia, in which chlorids may be even temporarily absent. A decrease is also found in pleu- risy, the nephritides, anemia, cachectic conditions, and chronic dropsic complaints; chronic lead poisoning; chronic mental diseases; cholera, diarrhea, and vomiting; acute articular rheu- matism; gastrectasis with pyloric stenosis; hyperchlorhydria, or gastric carcinoma. In benign pyloric stenosis there is a small amount of chlorids and also of N"; little chlorids with relatively large amount of N" in malignant stenosis. Estimation of Chlorids. Mohr's Volumetric Method. Take 10 c.c. of urine, dilute with 50 c.c. or more of ELO, add 1 / 2 c.c. of 20-per-cent. K 2 Cr0 4 (indicator), then titrate with standard AgNO 3 solution (same as for sanitary analysis of water) until a permanent pink or orange color appears. Each c.c. of the standard solution used is equivalent to 0.01 gm. NaCl or 0.006065 gm. 01. One c.c. of the standard solution should be subtracted, so as to allow for small quantities of organic substances that react with the silver salt. Purdy's Centrifugal Method. To 10 c.c. of urine add 1 c.c. of strong HN0 3 and 4 c.c. of AgNO 3 (dram to ounce). Invert 3 times, let stand for 3 minutes, then revolve for 3 minutes at 1200 revolutions. The percentage by weight of Cl equals 1 / 12 of the bulk percentage (usually 10 to 12 per cent.). PHOSPHATES. The earthy phosphates (Ca and Mg) amount to 1 to 1.5 gm. daily and are derived chiefly from the food and partly from the breaking down of nuclein and lecithin. The alkaline phos- phates, from similar sources, amount to 2 to 4 gm. in twenty- four hours. The total phosphoric acid is increased by a meat diet, fast- ing, and cerebral excitants. It is decreased on a vegetable diet, by pregnancy, and by cerebral depressants. URINE. 435 The earthy phosphates 'are increased in rickets (children) or osteomalacia (adults), chronic rheumatoid arthritis, diffuse periostitis; neurasthenia, melancholia, general debility, mental overwork, and central nervous diseases (epilepsy, meningitis); and in tuberculosis, carcinoma, leukemia, and acute yellow atrophy. The alkaline phosphates are greatly augmented in "phos- phatic diabetes": an affection characterized by acid polyuria, thirst, rapid emaciation, great nervous irritability, dyspepsia, and distressing lumbar pains. Both kinds of phosphates are diminished in all forms of Bright's disease and renal insufficiency and in chronic lead poi- soning. Less important is the decrease noticed in gout, rheu- matism, intestinal indigestion, anemia, chlorosis, empyema, hepatic cirrhosis, acute yellow atrophy, and intermittent and most acute fevers except meningitis. Earthy phosphates are held in solution in the urine by the acid reaction and by C0 2 . Heat drives off this gas and so ppts. the earthy phosphates. Alkaline phosphates are never sponta- neously pptd. The ratio of N to P 2 5 in the urine (normally 100 to 17) is greatly increased, and may be doubled in malignant diseases generally. Volumetric Determination of Total Phosphoric Acid (Ogden). Three reagents are used: 1. A standard solution of pure uranium ni- trate, containing 35.5 gm. per liter of distilled water; each c.c. corre- sponds to 0.005 gm. P 2 5 . 2. A solution of 100 gm. of sodium acetate and 100 c.c. of 30-per-cent. acetic acid in sufficient distilled water to make a liter. 3. A cochineal tincture prepared by digesting a few gm. of cochineal with 250 c.c. of diluted alcohol (1 part to 3 of water) and filtering after several hours. Take 50 c.c. of the urine, add 5 c.c. of No. 2 and a few drops of No. 3, and warm mixture to 80 C. over the water- bath. Then titrate the hot mixture with solution No. 1 until a faint, but distinct, permanent green color appears to mark the reaction with U as soon as the phosphoric acid is entirely pptd. Purdy's Centrifugal Method. To 10 c.c. of the urine add 2 c.c. of 50-per-cent. acetic acid and 3 c.c. of 5-per-cent. solution of uranium nitrate. Invert 3 times, let stand 3 minutes, and revolve for 3 minutes at 1200 revolutions per minute. The percentage, by weight, of P^Os equals Vss of the bulk percentage of uranyl phosphate [H(UO 2 )PO 4 ], usually from 8 to 10 per cent. To separate the earthy from tjie alkaline phosphates, the first step in Cook's centrifugal test for uric acid may be fol- lowed, and then the above reagents added. It should not be forgotten that "phosphaturia" depends not on the amount of earthy phosphates, but on the neutral or alkaline reaction of the urine. 436 CLINIC CHEMISTRY. CAKBONATES. A liter of normal human urine contains 40 to 50 c.c. of C0 2 ; if neutral or alkaline, over 100 c.c. This forms both nor- mal and acid salts with the alkalies and alkaline earths. The amount of carbonates in normal urine is generally minute, ex- cept after the administration of the salts of the vegetable acids or the ingestion of these acids as foods or medicine, giving rise to fixed alkalinity. Ammonium carbonate in appreciable quan- tity in freshly passed urine indicates decomposition of the fluid within the bladder, nearly always from chronic cystitis. The amount of iron present in the residue from a liter of urine varies from 3 to 11 mg. SULPHATES. The mineral sulphates (mostly K and Na) amount from 1.5 to 3 gm. daily, and are derived chiefly from meat and mus- cle, the contained S being oxidized to H 2 S0 4 , and this uniting with the metals. The proportion of mineral sulphates is increased by meat diet, active exercise, inhalations of pure 0, and ingestion of S compounds. It is decreased by a vegetable diet or salicylates. Pathologically the mineral sulphates show an absolute in- crease in acute fevers and inflammations, especially rheumatism, pneumonia, cerebritis, meningitis, and myelitis; also in ob- structive jaundice and both kinds of diabetes. A subnormal quantity is noted in acute and chronic renal diseases, eczema, chlorosis, leukemia, and carbolic acid poisoning (combines with H 2 S0 4 to form phenol-potassium sulphate). Generally an in- crease or decrease of mineral sulphates runs parallel with that of urea. Centrifugal Estimation (Purdy). To 10 c.c. of urine add 5 c.c. standard BaCl 2 solution (4 parts of BaCl 2 , 1 part of strong HC1, and 16 parts of distilled water). Let stand 3 minutes after shaking, and re- volve 3 minutes. The percentage by weight of S0 3 equals 1 / 4 bulk per- centage of BaS0 4 . The conjugate or ethereal sulphates originate chiefly from intestinal putrefaction, being formed in the liver from phenol,, skatol, paracresol, and indol. The principal members of the group are indoxyl-potassiu^n sulphate, or "indican" (C 8 H 6 - NO.S0 2 .OK), phenol-potassium sulphate (C 6 H 5 OS0 3 K), and skatoxyl-potassium sulphate (C 9 H 8 NO.S0 2 K). The ratio of ethereal to mineral sulphates is normally about 1 to 10. Indican occurs in excess on a meat diet; also in hypo- and achlor- hydria, constipation, and sometimes in diarrhea > URINE. 437 peritonitis, perityphlitis, typhoid fever, dysentery, empyema, hepatic or gastric carcinoma, putrid bronchitis, pulmonary gangrene, pernicious anemia, Addison's disease, resorption of extravasations, and later stage of phthisis and all wasting diseases. An enormous excess is often noted in cholera and intestinal obstruction or tuberculosis. Clinic Test for Indican. To V, test-tube of urine add V as much HC1 and a few crystals of KNO 3 . Boil the mixture, let cool, and shake with 2 c.c. of chloroform. If indican is normal in amount, the layer of CHC1 3 will be colorless. If indican is in excess, the chloroform on settling will be colored light blue to a deep purple, depending on the amount. Clinic Test for Phenol-potassium Sulphate. Distil 25 c.c. of the urine with 5 per cent, of H 2 SO 4 and add Br water to the distillate, get- ting a yellowish ppt. of tribromphenol. Salkowski's Method for Total Sulphuric Acid (Preformed and Conjugate S0 3 ). Take 100 c.c. of urine in a beaker, acidulate with 5 c.c. HC1, boil, and add BaCJ 2 until no more ppt. ensues. Collect ppt. on a small filter of known ash, and wash with hot distilled water till BaCl 2 disappears from filtrate. Then wash with hot alcohol and again with ether. Incinerate filter-paper and contents in a Pt crucible, cool, add a few drops of H 2 SO 4 (to change any BaS to BaSOJ, heat again to red- ness, cool in a desiccator, weigh, and deduct weight of crucible and ash. 100 parts of BaS0 4 = 34.33 parts S0 3 . Salkowski's Method for Ethereal Sulphates. Take 100 c.c. of clear, filtered urine; mix with an equal volume of alkaline BaCl 2 solu- tion [1 part cold, saturated BaCl 2 ; 2 parts cold, saturated Ba(HO) 2 ]; and stir thoroughly. After a few minutes filter into a dry graduate up to the 100 c.c. mark (half the urine), acidulate this portion with 10 c.c. HC1, boil, keep at 100 C. for an hour on the water-bath, and allow to stand for twenty-four hours or until completely settled. Then wash, dry, and weigh as for total sulphates. The difference between the total and the combined or ethereal sulphates represents the preformed or mineral sulphates. UREA. This compound is formed principally in the liver from the synthesis of C0 2 and NH 3 , with elimination of water. It is in part the product of retrograde metamorphosis of the tissues, blood, and secretions, and to a minor extent it results from the splitting up of unassimilated nitrogenous food, its antecedent, in this event, being leucin principally. About 85 per cent, of the N taken into the body by way of nourishment is excreted as urea, and approximately VT of the total potential energy of foods consumed escapes unutilized in the form of this com- pound. Urea is a neutral, crystalline substance with a bitter, cool- ing taste like that of saltpeter. It is highly soluble in water, and is used as a diuretic in cardiac cases of dropsy. It is lethal in the proportion of V 200 of the body-weight. According to 438 CLINIC CHEMISTRY. Bouchard, the symptoms of so-called uremia may be ascribed to six other toxic substances in addition to urea. One of these is a my otic; another, a sialagogue; a third, narcotic; a fourth depresses temperature; and K and another substance are con- vulsants. Some of these poisons are probably pigments, as pass- ing through charcoal lessens the noxious power of the urine by Y 8 . Urinary toxicity, as measured by intravenous injections E_ * 1.01 Q Cf Fig. 54. Doremus Ureometer. into animals, is usually heightened in infectious diseases; it is diminished in kidney diseases and is quite absent during uremia. The normal daily quantity of urea excreted by way of the urine is from 17 to 40 gm. (usually 30 to 40 gm.), or 15 to 32 mg. per kg. of body-weight. One-tenth less is excreted by women than by men of the same weight. Children, after the first month, have an output relatively double. In old age the proportion is reduced by half. Large persons obviously pass out more urea than small ones. The average percentage of URINE. 439 urea for adult males is about 2 per cent. The maximum ratio is six hours after meals; the minimum in the early morning. The urea of the urine is increased by proteid diet espe- cially,, and to a less extent by muscular exertion, caffein, opiates, electricity, the copious ingestion of liquids, alkaline chlorids, mineral acids, and a close atmosphere. It is decreased by a milk and vegetable diet, and to a less degree by fasting, loose bowels, free sweating, menstruation, alcohol, iron, lead, mer- cury, or digitalis. Pathologically an excess of urea is noted in acute febrile and inflammatory diseases, diabetes mellitus and insipidus, dyspneic conditions, malaria and severe blood diseases, minor chorea, paralysis agitans, some gastro-intestinal disorders, and in belladonna or phosphorus poisoning. A deficient quantity of urea is a most important feature of all forms of Bright's disease, and is due chiefly here to im- paired nutrition of the renal cells. A decrease is also observed in cachexia and malnutrition (more in gastric cancer than in simple inanition); hepatic carcinoma, cirrhosis, and acute yel- low atrophy; acute gout and chronic rheumatism; osteoma- lacia; chronic lead poisoning; diarrhea, cholera, and excessive sudation; simple anemia and leukemia; melancholia, imbecil- ity, catalepsy, hysteria; Addison's and Weil's disease; leprosy, pemphigus, impetigo. Detection of Urea. Evaporate a few drops of urine nearly to dry- ness with a drop of HN0 3 . Large, colorless, rhombic or hexagonal plates of urea nitrate may be seen with the microscope. Estimation of Urea. The most practical methods for clinic pur- poses depend on decomposition of urea by freshly made sodium hypo- bromite in a strongly alkaline solution. N 2 H 4 CO + SNaBrO = 3NaBr + CO 2 + 2H 2 O + 2N The CO 2 is absorbed by the alkali, and the N collects at the closed top of the instrument. The ureometer of Doremus is very simple and convenient. It is half-filled with 40-per-cent. NaHO solution, 1 c.c. of Br introduced, and after this the instrument is filled by adding more water. One c.c. of the urine is now carefully introduced under the long arm by means of the pipet. The bubbles of N collect at the top, and when effervescence ceases the percentage of urea can be read off directly from the graduations on the cylinder (best immersed in water to the level of the column of fluid). One c.c. of N represents 0.0027 gm. urea. Kjeldahl's Method to Determine Total Nitrogen. The rationale of this method is as follows: On prolonged heating of any nitrogenous substance with H 2 S0 4 all the N is converted into (NH 4 ) 2 S0 4 , which is decomposed on distilling with an alkali, and the liberated NH 3 collected in a known quantity of an n/ ]0 acid. The amount of the acid neutralized by the NH 3 is estimated by titrating with n/ 10 alkali, and from this re- sult the amount of N calculated. 440 CLINIC CHEMISTRY. Place 5 c.c. of urine in a 250 c.c. Kjeldahl flask; add 15 c.c. H 2 S0 4 and Y 4 gm. powdered CuS0 4 ; heat on a wire gauze under the hood till foaming ceases; then add 10 gm. powdered K 2 S0 4 and continue boiling gently till the liquid is a light green. Then add a few grains of powdered K 2 Mn 2 O 8 and heat again till fluid is light green. Allow to cool; transfer to a liter Erlenmeyer flask, adding the washings from the digestion flask; dilute to about 500 c.c., and add a few grains of powdered talc. Insert a doubly-perforated rubber stopper with a Reitmaier bulb and a thistle-tube reaching nearly to the bottom of the flask. A long strip of red litmus-paper should be hung from the neck of the flask Fig, 55. Kjeldahl Method, down into the liquid. Connect the upper end of the bulb with a con- denser and a 500 c.c. receiving flask containing 50 c.c. of n/ 10 oxalic acid. Pour 50 to 60 c.c. of 50-per-cent. NaHO into the large flask and distil over about 200 c.c. Then replace the receiving flask by another containing 10 c.c. of n/ 10 oxalic acid and some water, and distil over 100 c.c. Now add a few drops of alcoholic rosolic-acid solution and titrate with n/ 10 NaHO to a deep-pink color; the second, or check, flask should be free or nearly free from NH 3 . A blank experiment with the reagents, but without the urine, should be done to ascertain the amount of N, if any present in the reagents, and the result subtracted from the total. The difference between the number of c.c. of decinormal alkali taken and that left after neutralization gives, when multiplied by 0.0014 (N equivalent factor ), the amount of N in 5 c.c. of urine. URINE. 441 URIC ACID. The alloxuric bodies are derived chiefly from the cleavage of nucleins of the body-cells and of ingested nucleo-proteids. All these nucleins or purin bodies are precipitated by ammo- niacal silver-nitrate solution. The nuclein bases predominate in simple decomposition, while oxidation processes lead to the formation of uric acid, which normally exceeds the bases ten times in the output of alloxuric N, and may generally be taken as the criterion of nuclein metabolism. In gout, however, the lower oxidation products, such as xanthin, may exceed uric acid. Although urea may be formed artificially by oxidation of uric acid and many other organic compounds, there is no proof that in the metabolism of the organism uric acid represents a sub- oxidation analog of urea, or that the quantity of these two substances bears any necessary relation to each other. The normal daily output of uric acid is 0.4 to 0.8 gm.; of xanthin, 0.03 to 0.05 gm. The pure uric acid is crystalline, and requires 16,000 parts of cold or 1600 parts of boiling water to dissolve it. It is also soluble in alkaline hydrate's, carbonates, and phosphates. It appears to be formed chiefly in the liver and spleen by the synthesis of ammonia and lactic acid. It exists in the urine normally as urates, which are either neutral or acid, the latter class being subdivided into monacid or biurates, and triacid or quadriurates or tetraurates. The normal salts are readily sol- uble; acid urates much less so, especially in cold water. A brick-dust deposit of acid urates is commonly observed in acid concentrated urine, especially when chilled. The daily excretion of uric acid is increased by excess of proteid foods, especially meat-broths, glands, and young flesh; also by tea, coffee, cocoa, fats, alcoholics, and the administra- tion of thymus gland or nucleins. Its elimination is aided by the administration of sodium salicylate, disodic phosphate, colchicum, corrosive sublimate, or euonymin. The uric acid of the urine is decreased by a milk and vegetable diet; also by KI, large doses of quinin, coal-tar anti- pyretics, NaCl, alkalies, and the habitual ingestion of large quantities of water. Lithium salts and mineral acids diminish the elimination of uric acid temporarily by rendering it less soluble in the blood; the relief they give is transient and they eventually do harm. The most marked increase of uric acid occurs in leukemia: up to even 8 gm. daily. An excess is also noted in acute fevers and inflammations, dyspneic disorders, splenic diseases, malaria, scurvy, pernicious anemia, diabetes, rachitis, abdominal tumors, 442 CLINIC CHEMISTRY. cancer and cirrhosis of the liver, migraine, petit mal, neuras- thenia, chorea, and frequently in dyspeptic disturbances. In gout uric acid is diminished before and during the paroxysms, and greatly increased just after. An absolute decrease of uric acid is met with in chronic arthritis, chronic lead poisoning, progressive muscular atrophy, chlorosis and simple anemias, usually in diabetes, and in most forms of advanced kidney disease and chronic disorders gener- ally. Murexid Test. Evaporate a small portion of the urate or uric acid sediment to dryness in a porcelain dish, add a drop or two of HNO 3 to dissolve the residue, stir with a glass rod, and evaporate slowly to dry- ness. Allow to cool and add 1 or 2 drops of NH 4 OH, getting a beautiful purplish coloration due to murexid or ammonium purpurate, C 8 H 4 .NH 4 .- N 5 O 6 . On adding now a drop of NaHO the color changes to reddish blue and disappears on heating. The test can be rendered more delicate by holding a dish of urine and acid over another dish in which a dry NH 4 salt is volatilized. Gravimetric Estimation (Heintz). This simple, but not very ac- curate, test is made by adding to 200 c.c. of filtered urine, free from albumin, 10 c.c. of HC1, letting stand in a cool place for twenty-four hours, collecting the precipitated uric acid crystals on a dried and tared filter-paper, washing once or twice with cold distilled water, drying at 100 C., and weighing. Volumetric Method (Hopkins). This depends on converting all the uric acid and urates into ammonium urate, which is decomposed by HC1, and the separated uric acid estimated by titration with n/^ K L ,Mn 2 8 (standardized each time against hot decinormal oxalic acid containing a little H 2 SOJ, each c.c. of which is equivalent to 0.00375 gm. of uric acid. Saturate 100 c.c. of urine with NH 4 C1 (about 35 gm. usually neces- sary), let stand for two hours or longer with occasional agitation, filter, and wash ppt. three or four times with saturated solution of NH 4 C1. Then wash off the pptd. urate with a jet of hot distilled water into a small beaker, and heat just to boiling with excess of HC1. Cool and let stand for at least two hours to allow uric acid to separate completely; filter and wash crystals with cold distilled water. Now wash the uric acid off the filter with hot distilled water, add Na 2 CO 3 , warm until the acid is dissolved, and make up solution to 100 c.c. Transfer to a flask, mix with 20 c.c. of concentrated H 2 S0 4 , and titrate at once with the n/^ K 2 Mn 2 8 , which should be added slowly toward the end of the reaction, as shown by a transient pink coloration. To the final result, calculated in mg., 1 mg. should be added for each 15 e.c. of fluid in the last filtrate (need never be more than 20 or 30 c.c.), not taking the washings into account. When there is an abundant deposit of phosphates, these should be filtered off after complete pptn. by heat. The presence of albumin makes it necessary to continue digestion with HC1 longer in order to form the soluble acid albumin. If the urine contains much pigment, this should be removed from the urate ppt. by treating thoroughly with alcohol, and after acidulating heating the filtrate gradually to boiling and digest for some time on a water-bath, and then washing the separated crystals thoroughly. URINE. 443 Centrifugal Estimation (Cook). To 10 c.c. of urine add 1 gm. of Na 2 C0 3 and 1 c.c. of NH 4 OH. Shake till the carbonate is dissolved, centrifugate earthy phosphates, and pour off clear liquid into another tube. Add 2 c.c. of NH 4 OH and 1 c.c. of ammoniated AgN0 3 (dram to ounce), and separate silver urate as gelatinous urate, centrifugating until the reading is constant. One-tenth c.c. of ppt. represents 0.00176 gm. of uric acid. This method is accurate and very convenient. In addition to uric acid it ppts. the other alloxuric bodies, particularly the xanthins. To separate the latter, after getting the centrifugal sediment as above, transfer it to a smooth filter and wash with water till free of silver. The filter is now punctured and the ppt. washed into a liter-flask with 600 to 800 c.c. of water. The contents of the flask are acidulated with a few drops of HC1 and then saturated with washed H 2 S, boiled and quickly filtered through a small filter, and the Ag 2 J3 ppt. washed with boiling water. The filtrate is evaporated over a naked flame and then to dryness on the water-bath. The residue of alloxuric bodies is now treated with 25 c.c. of 1 to 30 H 2 S0 4 , heated to boiling over a small flame, and let stand for twenty hours. The acid dissolves the purin bases, but not uric acid: these are now separated by filtration and washing with the diluted H 2 SO 4 . The filtrate, containing the xanthins, may be tested by the centrifugal method given above, or by pptg. with ammoniacal AgN0 3 , incinerating, dissolving in a little HNO 3 , and ti- trating with standard NH 4 CNS solution. One part Ag is equivalent to 0.7381 gm. of alloxuric bases calculated as xanthin. HIPPTJRIC ACID. Hippuric acid, C 9 H 9 N0 3 , is normally present in large amounts in the urine of herbivora; in the autophagic condition of inanition, however, uric acid appears. It is a crystalline sub- stance averaging in daily amount in the human urine from 0.5 to 1 gm., and is of no present practical interest. It is increased by vegetable foods containing benzoic acid, such as cranberries, bilberries, prunes, greengages, etc., and by the administration of benzoic or cinnamic acid or toluol. Pathologically an excess is noted in acute febrile diseases, chorea, diabetes mellitus, and hepatic disorders. It is said to be diminished in amyloid de- generation of the kidney and absent in acute and chronic paren- chymatous nephritis. Detection. Evaporate urine to dryness with HNO 3 , heat residue in a test-tube, and note odor of bitter almonds, due to formation of nitrobenzol. CREATININ. This is reatin (C 4 H 9 N 3 2 ) minus water. It occurs in about the same quantity as uric acid and is probably derived from meat food. In alkaline urine it is replaced by creatin. Detection. ZnCl ? gives a crystalline ppt. [(C 4 H 7 N 3 0) 2 .ZnCl 2 ] of fine needles grouped in rosettes or sheaves. This test may be used quantitatively. 444 CLINIC CHEMISTRY. ALLANTOIN. Allantoin, C 4 H 6 N 4 0, is found only in a trace except in the urine of the newborn. It is increased by a meat diet and the administration of tannic acid. AMMONIA. This amounts in the urine to 0.5 to 0.8 gm. daily. An absolute increase is noted after fermentation of the urine, in fevers generally, and in diseases of the liver. It is sometimes greatly increased in carcinoma. A marked increase (1 gm. or more per diem) in diabetes forebodes coma. ENZYMES. Variable traces of pepsin and rennin are found in the urine, the maximum being four to six hours after meals. The ferments are said to be diminished or absent in gastric car- cinoma. CALCIUM OXALATE. About a decigram of oxalic acid is excreted daily in normal urine, chiefly as CaC 2 4 . When in excess this is pptd. as octa- hedral or dumb-bell crystals. An excess usually signifies -defi- cient oxidation. On the urine standing the crystals may form from urates and uric acid. The daily output of CaC 2 4 is increased by tomatoes, beets, rhubarb, spinach, sorrel, cauliflower, celery, carrots, beans, asparagus, apples, pears, grapes, pease, cabbage, claret, and effervescent drinks.* An excess is also observed in defective digestion of fats and carbohydrates (flatulent and nervous dys- pepsia); in malassimilation, the gouty habit, cancer, tubercu- losis, diabetes mellitus, and catarrhal jaundice. Oxaluria, mani- fested by vesic tenesmus and pain across the back, sometimes extending down the thighs or into the testicles, often accom- panies spermatorrhea, sexual neurasthenia, and functional mel- ancholia or hypochondriasis. BILE-SALTS. The biliary acids are present normally in the urine to the extent of 0.12 gm. daily. They are increased by active mus- cular exercise and diminished after meals. Pathologically an increase is noted in most blood diseases and particularly in liver disorders, especially the decline of bilious attacks. A decided URINE. 445 and persistent decrease takes place in chronic interstitial ne- phritis. Estimation. Oliver's test solution consists of 1 / 2 dr. of powdered pepton, 4 gr. of salicylic acid, a / 2 dr. of acetic acid and 8 oz. distilled water, repeatedly filtered till quite transparent. It reacts to 1 part iii 10,000 or more. To make the test the urine must be made perfectly clear (by filtering or shaking with magnesium fluid), be rendered acid, and have its sp. gr. reduced to 1.008. Twenty m. of the urine are added to 60 m. of the test solution. If bile-acids are present in normal quantity no immediate reaction occurs, but in a few minutes the urine becomes faintly opalescent. An excess is indicated by the immediate appearance of a distinct milkiness. The test can be made approximately quanti- tative by mixing equal parts of the test solution and of normal urine as a standard. A urine, for instance, of which 10 m. with 60 of the test solution produces the same degree of opacity as the normal standard mentioned, contains six times as much bile-salts as normally. MUCIN. A small quantity of mucin is present in all urines, espe- cially that of women, from vaginal admixture. An excess shows irritation or inflammation of the genito-urinary tract below the kidneys, by abnormal products, concentrated urine or urinary crystals, or following anesthesia. Mucinuria often precedes albuminuria in fevers. Excessive amounts, with abundance of epithelium, are encountered in cystitis, making the urine slimy and viscid. Detection. Mucin is pptd. in light-colored threads by vegetable acids or quite dilute mineral acids. The test is made more delicate by treating with alcohol for several hours, and acidifying the filtrate with acetic acid. COLORING MATTERS. These are, in general, best distinguished by the spectro- scope. Normal urobilin, C 32 H 40 N 4 7 , and its impure derivative, urochrom, are the chief coloring matters of the urine, amount- ing to about 4 gm. daily. They may originate either from bile or blood-pigment, but whether by oxidation or reduction is un- settled. They are somewhat resinous and not very soluble; hence they are removed to some extent by simple nitration. They are increased whenever destruction of red corpuscles is augmented, as in fevers generally, internal hemorrhages, heart and liver diseases, typhoid and septic conditions, scurvy, hemo- philia, and progressive pernicious anemia. A decrease is noted in diabetes, chronic nephritis, anemia, chlorosis, nervous dis- orders, extra-uterine pregnancy, and convalescence. They may be absent in total obstruction of bile. Detection of Urobilin. Acidulate 10 c.c. of urine with a few drops of HC1, shake with half as much amyl alcohol, and add a few drops of 44G CLINIC CHEMISTRY. 1-per-cent. alcoholic solution of ZnCl 2 rendered strongly, alkaline with NH 4 OH. A beautiful green fluorescence appears. Detection of Urochrom. Ppt. from solution with ammonium sul- phate and decompose with an acid, yielding a brown or black substance. Uroerythrin (purpurin, rosacic acid) is an amorphous, brick-red, iron-free substance, usually in combination with uric acid. The pink or reddish color of urates in deposits is due to uroerythrin. Its solution is colored dark green by an alka- line hydrate. An increase of this substance is observed in ma- larial fever, pneumonia, erysipelas, and hepatic cirrhosis or cancer. Uroroseinogen is a chromogen which develops a rose-red color on addition of a mineral acid. It is increased by vegetable diet and in conditions of malnutrition generally. GLYCEROPHOSPHORIC ACID. C 3 H 9 P0 6 is derived from nervous tissue and amounts nor- mally to 20 mg. daily. It is increased in nervous and febrile disorders and after chloroform anesthesia. ABNORMAL CONDITIONS. ALBUMINURIA AND GLOBULINURIA. True or renal albuminuria is persistent and usually consid- erable in amount. It is nearly always accompanied by casts, anemia, dropsy, or uremia. The access of the circulating pro- teins to the urine is attributable chiefly to impaired nutrition of the renal cells, due, in the first place, usually to chemic irri- tants (lead, alcohol) or toxins. Under this division come acute and chronic parenchymatous nephritis (large amount), chronic interstitial nephritis (small amount; sometimes absent), active and passive renal congestion (small quantity), amyloid de- generation (globulin sometimes exceeds albumin), malignant growths (small or moderate amount), renal cysts (5 to 30 per cent, by volume), movable and floating kidney and hydrone- phrosis (small amount in all), and the passage of excess of uric acid or calcium oxalate crystals or urates. Functional, or "physiologic," albuminuria is small in amount, transitory, and intermittent, in apparently healthy, but often neurotic, persons. It is rarely accompanied by hyaline casts. Common causes of this form are cold baths; severe men- tal or muscular exertion (bicycling); violent emotions; eating eggs, cheese, or meat to excess; and following anesthesia. Con- centrated urine with or without a deposit of uric acid or calcium URINE. 447 oxalate is frequently accompanied by a little albumin and a few cylindroids. In the cyclic, periodic, or postural, variety of albu- minuria the albumin disappears from the urine at night or during rest, recurring after meals or exercise. It is most often observed in male adolescents, and is attributed to renal conges- tion due to the erect posture. A trace of albumin is present for the first few days after birth, and in persons dead for some hours any retained urine may contain albumin from the macer- ated bladder-walls. Albuminuria of nervous origin is usually slight, and may be temporary or permanent. It is observed from high blood- pressure after epileptic attacks; also in surgical shock, con- cussion of the brain, acute intestinal obstruction, mania, delir- ium tremens, tetanus, exophthalmic goiter, and even occasion- ally in migraine. The circulatory form of albuminuria is usually slight in amount, and is most commonly due to passive congestion of the kidneys, as in organic heart disease and great weakness, or hepatic cirrhosis or emphysema. The same type is exemplified in compression of the renal veins by tumors or the pregnant uterus. In renal embolism the albuminuria is sudden and pro- nounced, with hematuria, disappearing gradually in a few days. Obstructive albuminuria is accompanied by temporary or permanent oliguria. A common cause of this type is impacted calculus, which is manifested further by aching pain in the loin, crystals and concretions, and bloody urine. Another cause is twist of the ureter by a displaced kidney, in which there is also severe paroxysmal pain like renal colic. Other causes of this nature are peritonitic adhesions, pressure on a ureter by a tumor or the pregnant uterus, and the uric-acid infarcts of infants. The hemic type of albuminuria depends on abnormal blood- changes, and, in addition to all the blood diseases, includes obesity, diabetes mellitus (irritation of sugar), gout, syphilis, nutrient enemata and intestinal autointoxication (disappears rapidly under intestinal antiseptics), and severe stomach dis- eases. Toxic albuminuria represents the local irritant action of chemicals in the blood on the kidneys; it is often attended by bloody or discolored urine. The most common agents giving rise to this symptom are turpentine, cantharis, saltpeter, car- bolic and salicylic acids, tar, creasote, iodin, lead, arsenic, mer- cury, alcohol, phosphorus, ether, chloroform, morphin, mineral acids, ammonia, and carbon monoxid. In the febrile type of albuminuria the hemic, toxic (toxins), 448 CLINIC CHEMISTRY. and circulatory forms are combined. We find albuminuria in nearly all acute inflammations and infectious fevers, especially scarlatina, in which albuminuria is post-febrile and due to acute nephritis. In diphtheria there is a nephritis during the attack. False or adventitious albuminuria is due to the presence of pus or blood from any part of the urinary tract, or to semen or vaginal discharges. In pyelitis there is often considerable albu- min (more than is accounted for by the pus in the urine): a distinction from cystitis. Albumin from leucorrhea is readily excluded by catheterization. Qualitative Tests for Albumin and Globulin. Roberta's Contact Test. Fill a clean wineglass one-half with clear or filtered urine. Incline the glass and slide under the urine about half as much of the nitric magnesian fluid (1 part of strong HN0 3 , 5 parts of saturated MgSO 4 solution), and let stand, if need be, for fifteen minutes. If albumin is present (1 to 50,000 or less) a white band will appear exactly at the junction of acid and urine. This zone is sharply outlined above and below, and appears best against a dark background. The width of the band depends mostly upon the degree of admixture of the two fluids, and is not so much a criterion of quantity as is its density. When there is a relative excess of uric acid a light-colored ring is to be seen at a little distance above the line of junction. Excess of mucus is manifested by a diffuse irregular cloudiness in the upper part of the urine. Various colorings (blue or red from indican; red from uroroseinogen; red-brown from iodids) are often to be seen about the line of contact. The test is one of the best for routine examina- tions, though it also gives a white zone with alkaloids, resinous medi- cines, and albumoses (cleared by heat). Heat Test. To a half-filled, wide test-tube of urine add a drop of 10-per-cent. acetic acid; if alkaline, add 2 or 3 drops until faintly acid. HNO 3 should not be used, since it would form soluble acid albumin. The addition of one-fourth as much saturated NaCl solution aids con- siderably in pptg. globulin and keeping mucin in solution. Heat the upper half of the urine to boiling (albumin coagulates about 75), and note white ppt. if it appears. When due to earthy phosphates this opacity clears up on adding a few more drops of acetic acid, whereas the albumin opacity remains and may become denser. The cloudiness of the upper part as compared with the lower is best discerned against a dark background. This is the oldest test for albumin, and quite certain. Ferrocyanid Test. Mix 1 part 50-per-cent. acetic acid and 2 parts 10-per-cent. K 4 FeCy 6 solution in a wineglass, and carefully overlay with the clear acid urine. A sharply-defined white zone at point of contact shows the presence of albumin. This reagent does not ppt. peptons, alkaloids, or phosphates, but may ppt. acid urates (it may then be cleared by heat). Spiegler's Contact Test for Albumin. The reagent contains 40 parts of mercuric chlorid, 20 parts of tartaric acid, 100 parts of white sugar, and 1000 parts of distilled water. If the ring is due to mucin a drop of HC1 clears. The test is said to react with 1 part of albumin in 150,000. URINE. 449 Quantitative Tests for Albumin. Purdy's Centrifugal Method. To 10 c.c. of urine add 3 c.c. of 10-per-cent. solution of potassium ferrocyanid and 2 c.c. of 50-per-cent. acetic acid. Set aside for 10 minutes, then revolve for 3 minutes at a uniform rate of 1500 revolutions per minute. The weight percentage is almost exactly one-fiftieth of the bulk percentage. Esbach Method. A graduated al- buminometer and a standard solution are employed. The solution consists of 10 gm. of picric acid, 20 gm. of citric acid, and distilled water to a liter. The al- buminometer tube is filled with urine to the letter u, then the test solution is added to R, and the two fluids well mixed. The tube is let stand for twenty- four hours, when the depth of the sedi- ment will show the amount of albumin in gm. per liter. The test is simple, but only approximate in its results, and the solution reacts with most other proteins as well as albumin. Gravimetric Method. This consists simply in acidulating 100 c.c. of the urine with acetic acid, filtering, boiling for a half-minute, filtering, drying until the weight of the filter and contents is con- stant, and then weighing. The test is easy, but consumes considerable time. ALBUMOSURIA. Albumoses were till recently confounded with peptons in the urine; so that at present the clinic significance of albumosuria is very indefinite. The condition has been noted in sarcoma of the ribs, osteo- malacia, tertiary syphilis, hemiple- gia, carcinoma, diphtheria, double pneumonia, multiple myelomata, and muscular and renal atrophy. The reactions of the different pro- teoses are shown in the table on page 450. u J Fig. 56. Esbach's Albuminometer. PEPTONURIA. A slight amount of pepton frequently accompanies albu- minuria. A considerable quantity is generally of pyogenic origin (suppurative meningitis or appendicitis, empyema, pul- 450 CLINIC CHEMISTRY. W 1 * < ^ 2 8 si 1 g as g| a fl'o ca'g fl 00 ft "o * ill 1 pli ||| S5 t PI I t Pi 1 1 I oo * 5 3 3 3 5^* 2 3' 2 3 i a gS o< A E _^ co^o i o ,0 jf JTSIS r^^'j^ SiS pj >j ^ * r AND COLD ! E SOLUTIONS I CENT. NAC ie as albumi I c 1 .sit |B0 3 3 1 3 1 R SS pi 1 1 |ill ^1 d "".2 ' g K*S s ^ -*J Sj i? W || c Q} ^3 ^> o g 1 3 4| H^ OJ "S * ra'S 2 1 GQ a |i! 1 3 1 |lil i 8 ' A! | A| ^ 'a 2a 5 s 1 b S o "s 1 s l " 1 II * URINE. 451 monary tuberculosis, etc.). It is also noted during resorption of inflammatory effusions, as in pneumonia, and in puerperal conditions, intestinal ulceration, acute infections, toxic condi- tions, and cancer of the liver. Detection. To separate the other proteins, if present, the urine should be saturated while boiling with ammonium sulphate several times. Peptons, if present, may then be pptd. with Tanret's reagent (KI, 3.22 gm.; HgCl 2 , 1.35 gm.; H 2 O, to 100 c.c.). If other proteins are not present peptons may be pptd. with tannin from the decanted fluid after pptg. the phosphates in the centrifuge. FIBRINURIA. Without accompanying hematuria, this condition is seen only in chyluria and diphtheritic inflammation of the urinary passages. Macroscopic fibrinous plugs are sometimes found in the urine of pyelitis and ureteritis. They do not dissolve in hot water, but are acted on readily by pepsin and dilute HC1. GLYCOSTTRIA. The presence of dextrose (and levulose) in the urine may be classified etiologically as artificial, transitory, and diabetic. Artificial glycosuria is produced by excess of carbohydrate food, sweet wines, grapes, and confectionery; also by thyroid extract, and in chronic lead poisoning; in asphyxia; and in poisoning by phosphorus, coal-gas, ether (inhalations), curare, HCN", H 2 S0 4 , strychnin, Hg, alcohol, glycerin, amyl nitrite, or nitro- benzol. Phloridzin causes glycosuria through the action of this compound on the kidneys. Slight or transient glycosuria is noted especially in fat elderly men and women; it is quasinormal, and is due to a lowering of the sugar-consuming power of the tissues. In other forms of non-diabetic glycosuria there is some pathologic agency affecting the glycogen-storing function of the liver, either through the nervous system, the stomach, or the pan- creas or by directly attacking the liver. Gouty glycosuria is allied to the alimentary glycosuria of obesity. Senile glycosuria probably depends upon the greatly reduced capacity of the aged body to consume sugar. The form which follows falls and in- juries or nervous lesions, such as cerebral apoplexy, is analogous to the sudden discharge of accumulated liver-glycogen, caused by experimental lesions. In neurasthenia the glycogen-storing function of the liver is permanently depressed, and hyper- glycemia and diabetic symptoms may ensue. The influence of boils, ulcers, carbuncles, and many acute infections, particu- larly influenza, in causing glycosuria, seems to depend upon the 452 CLINIC CHEMISTRY. toxins produced in these conditions, and it usually disappears along with the fever. True diabetic glycosuria is persistent and usually marked (up to 10 per cent.), with polyuria, polydipsia, polyphagia, ema- ciation, and pruritus. It is often accompanied with acetonuria, lipuria, alkaptonuria, and oxybutyria. The most marked lesion known to be capable of producing diabetes mellitus is wasting of the pancreas. Haines's Test. The solution consists of V 2 dr. of pure CuS0 4 dis- solved in Y 2 oz. of distilled water; 1 / 2 oz. pure glycerin; and 5 oz. liquor potassse. The object of the glycerin is to prevent the precipitation of the copper hydrate that is formed. Take about 1 dr. of the solution in a test-tube, bring it to a boil, and add 6 to 8 drops of the urine while boiling. If glucose is present a yellow or red ppt. is at once thrown down. The yellow appears first and is due to reduction to cuprous hydrate; the red sediment is cuprous oxid. The boiling should not be continued longer than a minute., since uric acid and other substances will reduce copper solutions on prolonged heating or even on standing, giving a greenish opacity. The grayish cloud of earthy phosphates pptd. by the alkali of the solution should not be mistaken for an indication of sugar. This is the best qualitative test for appreciable amounts of sugar in the urine. It reacts with 0.02 per cent, of glucose. Fehling's Test. This older test is preferred by some, though it has a number of disadvantages. The solution contains 34.639 gm. of CuS0 4 , 500 c.c. of NaHO solution (sp. gr., 1.12), and 173 gm. of c. p. Rochelle salts in enough distilled water to make a liter. Each c.c. of the solution is exactly decolorized by 50 mg. of dextrose. The tartrate serves the same purpose as the glycerin in Haines's test, and reduction takes place in the same manner. The copper solution and the Rochelle- and-soda solution are best kept separate till used, mixing equal parts and adding the urine drop by drop till a quantity equal to the mixed reagent is added. Fehling's solution is reduced by sugar, uric acid, creatin, hippuric acid, carbolic acid, alkaloids, etc. Bottger's Test. Bismuth salts are likewise reduced to the metallic state by sugar in the presence of alkali. Add to the urine an equal volume of liquor potassae and then a little subnitrate of bismuth. On boiling the mixture turns gray or black according to the amount of sugar present. .Traces of S cause a similar reaction; hence the test is not applicable in albuminous urine. Fermentation Test. Fill the saccharimeter (an inverted test-tube will answer) with the urine after mixing well with a little lump of fresh yeast. Let stand in a warm place for twenty-four hours and notice whether any gas (CO..,) has collected in the upper part of the instrument. The test is very certain when there is considerable glucose present, but unfortunately does not show any result with less than 0.5 per cent, of sugar, owing to the fact that water absorbs its own volume of CO 2 . Some specimens of yeast evolve gas spontaneously; hence it is well to use two tubes, one as a control experiment with water. To utilize the fermentation method quantitatively Roberts directs to fill two 4-ounce bottles with the urine, put a lump of yeast in one, cork this bottle loosely and the other tightly, and keep both bottles in a warm place (80 to 90 F.) for twenty-four hours. Then filter both urines and take their sp. gr. The difference in density represents chiefly PLATE VI. CRYSTALS OF PHENYLGLUCOSAZONE. (After v. Jaksch.) URINE. 453 the CO 2 given off from fermentation of the sugar, and each degree of loss in weight is equivalent to 1 grain of glucose to the ounce. Williamson's Test. A delicate (0.05 per cent.) and accurate test for glycosuria, and one that does not react with the common reducing agents of normal urine, is the microchemic test with phenyl-hydrazin, forming beautiful needle-shaped crystals of phenyl-glucosazone, which are bright .sulphur-yellow in color and are arranged singly or in stellate groups and melt at 204 C. C 8 H 12 9 + 2C 6 H 5 .N 2 H 3 = CjgHaNA + 2H 2 + H 2 In an ordinary test-tube place 1 / 2 inch of powdered phenyl-hydrazin hydrochlorate, then solid sodium acetate for another half-inch. Half- fill the test-tube with urine and boil for two minutes, the powders pass- ing into solution. Let cool in the rack and examine sediment under rather a low power. Quantitative Estimation of Glucose. The best method for med- ical purposes is that of Purdy. His solution consists of 4.752 gin. of pure CuSO 4 , 23.5 gm. of KHO, 350 c.c. of strong NH 4 OH (sp. gr., 0.9), 38 c.c. of c. p. glycerin, and distilled water to make a liter. The copper salt and glycerin are dissolved separately from the KHO, then mixed, and after cooling the ammonia and the rest of the water added. Thirty- five c.c. of the solution are reduced on boiling by exactly 0.02 gm. of dextrose. Put 35 c.c. of the test solution in a flask, dilute with about twice as much distilled water, and bring to the full boil. Fill buret to the zero-mark with the urine to be tested, which is run down slowly into the boiling reagent drop by drop until the blue color begins to fade; then still more slowly, 3 to 5 seconds between successive drops, until the test solution is left quite colorless and transparent. The per- centage of sugar in the urine is readily calculated by dividing 0.02 by the number of c.c. of urine required to effect decolorization. The test solution is stable and the end-reaction is perfect. LACTOSTTRIA. Sugar of milk is occasionally present in the urine of women near the end of gestation and in nursing women, especially when there is obstruction to the flow of milk, as in mastitis. It is also observed in nursing infants with digestive derangements. Detection. If the urine reduces copper solutions feebly, does not ferment with yeast, and rotates polarized light strongly to the right, lactose is probably present. The phenyl-hydrazin test also yields clus- ters of yellow needles of phenyl-lactosazone. INOSITTJRIA. Inosite is often present in the urine in diabetic conditions, sometimes taking the place of glycosuria. It has also been noted in nephritis, typhus, phthisis, syphilis, and lesions of the medulla. Detection. Evaporate with concentrated HN0 3 nearly to dryness on a Pt dish; moisten residue with a few drops of NH 4 OH and CaCl 2 454 CLINIC CHEMISTRY. solution; then evaporate again to dryness. A vivid rose-red color ap- pears with even 1 mg. of inosite. ACETONTJRIA. This condition signifies, in general, albuminous decompo- sition, as in advanced diabetes mellitus, infectious fevers, ad- vanced tuberculosis, inanition, carcinoma, death of fetus in utero, excess of animal diet, certain psychoses, strangulated her- nia, and eclamptic seizures in infants. Legal's Test. Treat Y 4 test-tube of urine with a few drops of fresh concentrated solution of sodium nitroprussid, add a few drops of acetic acid (to prevent reaction with creatinin), and render mixture alkaline with NH 4 OH. An affirmative reaction is shown by the gradual develop- ment of a red color, deepening to purple-red. Lieben's Test. Distil 500 c.c. of the urine after adding 0.5 c.c. of H 3 P0 4 (to prevent evolution of gases), and use the first 10 c.c. of dis- tillate. To this add a few drops of a dilute solution of iodopotassic iodid and NaHO. In the presence of even a trace of acetone crystals of iodoform are pptd. and are easily recognized by the odor. DIACETURIA. Diacetic acid, C 6 H 10 3 , is a colorless liquid, turned red by ferric solutions. It is always of abnormal significance, particu- larly in diabetes mellitus, where its presence forewarns of coma. This compound is also observed at times in fevers, especially in children; appendicitis, pneumonia, pleurisy, pericarditis, scurvy, and diseases of the brain. Diaceturia also occurs as an idio- pathic and very fatal autointoxication, manifested clinically by vomiting, dyspnea, jactitation, and coma. Von Jaksch's Test. Add to the urine slowly a rather concentrated solution of Fe 2 Cl 6 , filter off the phosphatic ppt. and add more of the iron solution. If a claret-red color appears, boil a fresh portion of the urine and treat another portion with a little H,SO 4 and extract with ether. If the iron solution gives no reaction with the boiled urine, but gives a claret-red hue with the ethereal extract, diacetic acid is prob- ably present, especially if the urine is rich in acetone. The object in boiling and treating with ether is to exclude antipyrin, quinin, thallin, sulphocyanates, and salicylic, carbolic, acetic, formic, and beta-oxy- butyric acids. OXYBUTYRIA. Beta-oxybutyric acid, C 4 H 8 3 , is an odorless syrup readily miscible with water, alcohol, and ether. It is an optically active substance, and, if urine is dextrorotatory after fermentation with yeast, it is very probable that this compound is present. Oxybutyria is noted in severe cases of diabetes mellitus, often presaging coma; also occasionally in infectious fevers. URINE. 455 ALKAPTONTJRIA. Alkapton is a yellow, resinous, nitrogenous substance thought to be derived from the putrefaction of tyrosin. Alkap- tonuria is observed in obscure derangements of metabolism, especially in children and phthisic patients. Owing to the pres- ence of pyrocatechin, uroleucic acid, and other reducing sub- stances, the urine darkens on standing (more quickly on adding Fe 2 Cl 6 ), emits an aromatic odor, and reduces copper solutions. GLYCTJRONIC ACID. This compound, C 6 H 10 7 , appears normally in the urine in very small amounts combined with K 2 S0 4 . In appreciable quantity it is very likely to be mistaken for sugar. It is a syrupy liquid insoluble in ether; dextrorotatory itself, but in combination levorotatory. It gives a crystalline compound with phenyl-hydrazin. Glycuronic acid appears in the urine in a combined state after the administration of any of the following drugs: Chloral (with urochloralic acid, CC1 3 CH 2 OH), camphor (camphoglycu- ronic acid), naphthalene, turpentine, chloroform, morphin, curare and arsenic, copaiba, acetanilid, salol, salicylic acid, sulphonal, and nitrobenzol. If the urine is dextrorotatory and reduces copper solutions, but does not ferment with yeast, this acid is probably present. MELANURIA. In this condition the urine becomes dark or even black on standing or on heating with nitric acid or ferric chlorid. It is specially significant of melanotic sarcoma in any part of the body, but the pigment may not begin to appear in the urine till the growth is far advanced. Melanin is also sometimes found in the urine in cancer of the stomach, marasmus, inflammations, and severe chronic malaria (microscopic pigment-particles). Zeller's Test. Br water causes a yellow ppt. that gradually blackens. CHOLTTBJA. Unchanged bile-piginents in the urine cause it to have a dark greenish-yellow color, with a yellow foam on shaking. They are present in all diseases accompanied by jaundice (often before the appearance of the yellow hue in the skin), whether from obstruction of the bile-ducts; disease of the liver; or decomposition of the blood, as in pernicious anemia, malaria, or typhoid fever, or after internal hemorrhages. Poisoning by P or arsin is manifested by choluria. 456 CLINIC CHEMISTRY. Rasmussen's Test. Shake well together 1 c.c. each of urine and ordinary ether with 6 m. of tincture of iodin. On standing the ether and I separate as an upper layer, while the stratum of urine below is colored a brilliant green if biliverdin is present. Gmelin's Test. Place a drop of urine on a white porcelain plate, and allow a drop of nitrous or fuming nitric acid to touch and mingle with the other drop. In the presence of bile a play of colors will soon appear in the order of green, blue, violet, red, and yellowish. The green color is indispensable to prove the presence of bile-pigment. Stercobilinuria has been observed in hepatic cirrhosis, chronic malaria, scurvy, pernicious anemia, hemophilia, and after internal hemorrhages; also in febrile and infectious dis- eases, particularly pneumonia. CYSTINTJRIA. Cystein, NH 2 CH 3 SHCCOOH, is a product of proteid me- tabolism, never normally found directly in the urine or in the body. It is converted by atmospheric into cystin, 2CH 3 - CSKE 2 COOH: a rare urinary sediment. Cystinuria is a family disease, seen usually in children and young male adults. It has been noted in connection with he- patic disorders, renal degeneration, chlorosis, struma, intestinal putrefaction, and acute articular rheumatism. It is always accompanied by diaminuria originating in putrefactive processes due to specific bacteria in the intestines. CHYLTIRIA. Chyle in the urine is a tropic condition, for the most part, and due to the nightly migrations of the filaria sanguinis hominis. The urine in filariasis contains also albumin (coag- ulates spontaneously) and often blood, which gives a pink color; the parasite may be found in the night urine. Earely chyluria is brought about by great abdominal compression or by trauma or disease setting up fistulas between the lymph-canals and the urinary channels. The milky appearance is cleared by shaking with ether. LIPURIA. Fat-drops, sometimes forming an oily upper coating on the urine, are occasionally encountered in chronic parenchymatous nephritis, phosphorus poisoning, fatty degeneration of the kid- neys, diabetes mellitus, calculous pancreatic disease, acute yel- low atrophy, pregnancy (normally), after fractures of the long bones, opening of an abscess into the urinary tract and follow- ing the administration of large amounts of fixed oils (rarely form pseudocalculi); also rarely in heart disease, hydronephro- URINE. 457 sis, gangrene and pyemia of joints. The fat is readily detected by the microscope and by its solubility in ether. The fat in chyluria is better emulsified, appearing as mere specks. LIPACIDURIA. Lactic acid is occasionally present in the urine in cases of hepatic cirrhosis, acute yellow atrophy, diabetes, leukemia, osteomalacia, rachitis, phosphorus poisoning, and trichiniasis. HEMATURIA. One part of blood in 1500 makes the urine smoky; 1 to 500, bright red (chocolate-brown if much acted on by the urine). Blood in the urine is best determined by the use of the micro- scope. A good chemic test for blood coloring matter is to add to a few c.c. of tincture of guaiac in a test-tube a few drops of ozonized ether, then underlay the mixture with urine. If hemo- globin is present a blue ring will soon appear at the line of junction of the two fluids. This ring does not disappear on boiling, as does a similar zone due to pus. When the blood is from the kidney the urine appears smoky; the blood is usually slight in quantity, acid, and well mixed; and blood-casts are to be found. From the renal pelvis the blood is generally profuse and well mixed with the urine; this hemorrhage is generally unilateral, as shown by cystoscopy or ureteral catheterization, and tailed columnar epithelia pre- vail. Hemorrhage from a ureter is manifested by long clots, like earthworms in size and shape. There is renal colic in the passing, just as in some cases of tubal or pelvic hemorrhage, and hematuria may alternate with normal urine when the pas- sage is stopped. Blood from the bladder appears in large, irregular, bright-red clots (sometimes dark brown if urine is quite alkaline) at the end of micturition. If the bladder is washed out with borax solution until what comes away is clear, and the solution is again injected at once, it will come away bloody. Cystoscopy gives definite information as to the cause of the bleeding. Blood from the prostate appears toward or at the end of micturition, which is usually difficult. Bright blood from the anterior urethra is passed at the beginning of micturi- tion and during the intervals, or can be stripped out. From the posterior urethra it is usually slight in quantity and comes at the beginning or end of micturition or both, sometimes clotting. Pink semen indicates a hemorrhage from the seminal vesicles. Blood from the vulva, vagina, or uterus is readily distinguished by the fact of menstruation, by inspection, by washing, and if necessary by catheterization. 458 CLINIC CHEMISTRY. The following are the more common causes of hematuria: Trauma, acute nephritis, acute exacerbations of chronic nephri- tis, active congestion, filariasis, embolism, thrombosis, urinary tuberculosis, malignant growths (profuse and apparently cause- less), calculi (hemorrhage usually follows exertion; pain on micturition or renal colic), renal cysts, floating kidney, blood diseases, irritant drugs (turpentine, cantharis), neuropathic angioneurosis, acute infections, vicarious menstruation, strong mental emotions, uric acid infarcts, severe inflammations or ulceration, benign vesic growths (papilloma, myoma, fibroma, myxoma bleeding profuse), varicose veins at neck of bladder, sudden emptying of dilated bladder, and the distoma hasma- tobium. HEMOGLOBINTIRIA. The presence of blood coloring matter without the corpus- cles shows extensive destruction of red blood-corpuscles, as in acute infections, severe burns, transfusion of blood, absorption of hemorrhagic effusions, Winckel's disease, and poisoning by KC10 3 , quinin, I, coal-tar derivatives, glycerin, mushrooms; carbolic, hydrochloric, sulphuric, and pyrogallic acids; phos- phorus; and H 3 P, H 3 As, H 2 S, and CO. Hemoglobinuria is also seen in hepatic insufficiency and following exposure to cold or violent physic exertion. So-called idiopathic hemoglobinuria is met with at times in malaria, and is accompanied by chills, fever, lumbar pains, vomiting, and diarrhea. The urine is porter-colored and albuminous. The paroxysms occur at inter- vals of weeks or months and last a few hours. PYTJRIA. Purulent urine is cloudy and deposits a creamy layer. Pus from the kidney tubules is usually small in amount (unless from abscess) and is attended by casts and acid urine. A larger amount is met with when the renal pelvis is involved; the urine is usually acid and the pus settles quickly; micturition may be frequent, but not painful. In vesic pyuria the amount of pus is usually considerable; the urine quickly loses its acidity or is already fetid, ammoniacal, and viscid; and the pus settles slowly and partially; micturition is usually both frequent and painful. The sudden appearance of a large quantity of pus is indicative of an abscess rupturing into the urinary channels. In gonorrhea one can tell whether the inflammation has ex- tended to the posterior urethra by having the patient pass water into two glass vessels. If the first portion only of the urine contains pus-threads (tripper faden) infection is restricted URINE. 4.59 to the portion of the canal in front of the "cut-off" muscle, and vice versa. Epididymitis with suppuration is manifested by yellowish or greenish-yellow semen. Pus from the kidney may be due to tuberculosis, bacterial invasion, trauma, new growth, calculus, pyemic abscess, or ex- tension of gonorrhea; prostatic obstruction predisposes to up- ward extension of any infection. Pus from the ureter usually means the passage of a calculus or the resulting inflammation. Pus from the bladder may be due to prostatic obstruction, gon- orrheal stricture, tubercle, calculus, trauma, or new growth. Pus from the prostate depends upon prostatic hypertrophy, gon- orrhea, tubercle, trauma, stone, or tumor. Pus from the urethra may be due to simple or gonorrheal urethritis, trauma, tubercle, chancroid, syphilitic ulceration, or malignant disease. Pus milked from the seminal vesicles is usually of gonorrheal origin, but may depend on sexual excesses, tubercle, or new growth. Donne's reaction is the gelatinization that takes place on adding some solid KHO to a sediment of pus. PTOMAINS. Griffiths has isolated special alkaloids from the urine in the following diseases: Parotitis, scarlatina, diphtheria, mea- sles, pertussis, glanders, pneumonia, epilepsy, erysipelas, puer- peral fever, eczema, influenza^ carcinoma of the uterus, pleu- ritis, and angina pectoris. Albu has also found toxins in the urine of patients with hectic phthisis, exophthalmic goiter, tetanus, pernicious anemia, diabetic coma, and urticaria due to autointoxication. MICROCHEMISTRY OF THE URINE. The presence of an unorganized sediment in urine signifies, as a rule, merely a change in temperature or chemic reaction, owing to which the solvent power of the fluid for the substance pptd. is diminished or nullified. The presence of such a sedi- ment bears no relation whatever to the amount of ingredients in the urine. With the exception of the slight cloud of mucus seen normally in cooled urine, organized urinary deposits are always pathologic. On the whole, however, cloudy urine is a less serious indication than is a very clear renal excretion, such as we see in diabetes mellitus and chronic Bright's disease. For the accurate study of urinary sediments the micro- scope is absolutely essential. A centrifugal machine for the rapid settling of casts and other suspended matters must be considered a necessary adjunct to the microscope. With the 460 CLINIC CHEMISTRY. aid of the centrifuge one gains not only more delicate, but more correct, results, since the urine can thus be examined in a per- fectly fresh condition before any chemic decomposition takes place with precipitation of uric acid, calcium oxalate, earthy or triple phosphates, and other secondary sediments resulting from acid or alkaline fermentation. CRYSTALS. The only colored urinary crystals are uric acid, ammonium urate, and rarely cystin and acid urates, hematoidin, leucin, Fig. 57. Sodium Urate Crystals. and tyrosin. All these crystals owe their color to urochrom, and are darker or lighter, according to the amount of this pig- ment. Uric acid (Fig. 1, Plate VII) is pptd. from its normal occur- rence as urates by an increase of acidity, particularly when the urine is of low sp. gr. and deficient in pigment. To the naked eye uric acid appears as a crystalline sediment resembling grains of red sand or Cayenne pepper. Under the microscope it appears as large and beautiful crystals of various forms, the lozenge shape predominating, frequently arranged in a superimposed manner into rosettes and other composite combinations. Uric acid PLATE VII. >'///. / xf" V - v^> ,/. /.& ^f V- Fig. 3 /y^.x? URINARY CRYSTALS. URINE. 461 crystals are readily distinguished from any other (except urates and cystin) by their lemon-yellow or red-brown color. Uric acid deposits are frequently due to excess of meat in sedentary livers and in the excessive catabolism ("uric acid diathesis") of deficient oxidation. They are also observed in fevers, after gouty paroxysms, in the early stage of chronic in- terstitial nephritis, and during recovery from aeute exanthems or acute nephritis. Acid urates are usually amorphous, but rarely appear as fan-shaped and circular radiating crystals of a reddish-brown Fig. 58. Cptin Crystals. or yellowish tint. Uric acid and urates are readily soluble in alkaline hydrates. Ammonium urate (Fig. 3, Plate VII) appears in the urine after it has undergone alkaline fermentation; it usually takes the form of little brown balls with spicules the so-called "thorn- apple," "hedge-hog" crystals; sometimes a "sheaf of wheat" clump of fine needles with a central spherule. Cystin is rarely met with as a lemon-colored deposit in faintly acid urine. It contains 26 per cent, of S, and on stand- ing for some time is apt to turn of a greenish hue and develop the odor of H 2 S. The microscope reveals highly refractive 462 CLINIC CHEMISTRY. "mother-of-pearl" hexagonal crystals, which are distinguished from those of uric acid having a similar appearance by treating the specimen on the slide with a drop of KE 4 OH. The ammo- nia is allowed to evaporate, with the result that the cystin crystals remain unchanged, while uric acid crystals are changed to ammonium urate spherules. Cystin is soluble in HC1; uric acid is not. Leucin and tyrosin (Fig. 2, Plate VII) are nearly always associated in the urine, being observed chiefly in acute yellow atrophy and phosphorus poisoning. The former appears in the Fig. 59. Calcium Oxalate Crystals. shape of somewhat striated yellowish spheres resembling oil- drops, from which they are differentiated by their insolubility in ether. Tyrosin is observed in the form of tufts or sheaves of very fine needles, snow-white when viewed en masse. Hematoidin (bilirubin) crystals are often deposited in urine containing bile and following hemorrhages. They appear as yellow or ruby-red needle clusters or rhombic plates, which show a green rim on adding a drop of HN0 3 . The colorless crystals of the urine include triple phos- phates, calcium oxalate, calcium phosphate, calcium sulphate, cholesterin, calcium carbonate, and fatty acid crystals. URINE. 463 The so-called "triple" phosphate (Fig. 5, Plate VII) of am- monium and magnesium, NH 4 MgP0 4 , is seen normally in urine which has undergone ammoniacal fermentation after voiding. When present in freshly passed urine such a deposit is always pathologic, indicating ammoniacal decomposition within the bladder as both a cause and a result of cystitis. Triple phosphate crystals are relatively large and colorless, having the form ordi- narily of a triangular prism with beveled ends; hence the name "coffin-lid" crystals. Collections of these crystals often form a glistening film on the surface of stale urine and the sides of the Fig. 60. Hippuric Acid Crystals. container; this appearance, under the designation of "kiestein," was formerly believed to be a sign of pregnancy. CaH(P0 4 ) crystals are sometimes observed in feebly acid urine as wedge-shaped or conic scaly forms, usually grouped in a radiating manner point to point. They are distinguished, like phosphates generally, by their ready solubility in acetic acid. A deposit of this nature is rarely met with in health when the urine is rich in lime-salts, as after a full meal of certain vege- tables. Pathologically the deposit has been noted in phthisis, pyloric cancer, calculi, and obstinate chronic rheumatism. Calcium oxalate (Fig. 4, Plate VII) is rather a common sedi- 464 CLINIC CHEMISTRY. inent, often mistaken macroscopically for a cloud of mucus, with which, for obvious reasons, it is often co-existent. It is found both in acid and in alkaline urine. CaC 2 4 crystals are usually octahedral in shape, giving the appearance of a square crossed by two diagonal bright lines, like the back of a square envelope. They are much smaller than those of the triple phosphate, from which they are further distinguished by their insolubility in acetic acid. Much rarer forms of calcium oxalate crystals are those resembling a dumb-bell, and the oval and circular crystals with bright centers showing biconcavity. Hippuric acid is occasionally met with as a slight urinary sediment, in the form microscopically of fine needles or of four- sided rhombic prisms with beveled ends and edges. It is sol- uble in alcohol; insoluble in acetic acid. Cholesterin in large, thin, and nearly transparent plates with broken corners is occasionally encountered in the urine of cystitis, diabetes, chyluria, tabes, pregnancy, jaundice, ne- phritis, fatty degeneration of the kidneys, and after evacuation of an abscess into the urinary tract or the long-continued ad- ministration of bromids. Treated with dilute H^SC^ and then with I solution, these crystals turn violet, turquoise, then blue. Calcium sulphate is a very rare sediment, occurring only in acid urine of high sp. gr. The crystals are radiating, color- less needles. Calcium carbonate is also an exceedingly rare deposit in the human renal secretion. It is found only in alka- line urine as a whitish deposit that dissolves with effervescence in dilute acids, and which under the microscope is shown to be composed of concretions of little spheroids. Fatty acid crystals are sometimes seen with the microscope as fine, bright needles adhering to fat-drops and fatty cells. GRANULES. Acid urates of K and Na are, by far, the most common urinary deposits, forming sediments that are usually amorphous and vary in color from a light pink to a deep red rarely color- less. Under the microscope they appear as pink, granular, moss-like beds, which clear up on warming or on treating with a drop of NH 4 OH. Calcium urate is of rare occurrence as a urinary sediment, appearing as a light-gray, amorphous powder. Like the other urates, it is found only in urine of acid reaction; these mixed urates constitute the well-known "brick-dust" de- posit of cold and dense urines. The white urates of young infants consist chiefly of amorphous ammonium urate. Urine rich in urates after being in a bottle for some time leaves a very adherent film of these on the inside of the flask. URINE. 465 The earthy phosphates (Ca and Mg) constitute the most common sediment of alkaline urines. They are easily soluble in acetic acid, being in this way discriminated from other uri- nary deposits. The color of a phosphatic sediment is usually gray, but in the presence of hemoglobin has a reddish tinge, and" sympexia from the prostate are often colored blue or yel- lowish. Cloudy urine from these granular phosphates is very often seen after a full meal of vegetables, but the constant presence of phosphaturia indicates, as a rule, a low general metabolism. The black pigment melanin occurs in lumpy, microscopic granules, soluble only in boiling mineral acids or strong solu- tions of the caustic alkalies. Irregular masses, or rhomboidal crystals, of indigo are rarely noticed in the urine, especially when this has undergone putrefactive changes with oxidation of indican. The blue par- ticles may also be derived from the underwear. CASTS. Tube-casts, or cylinders, are molds of the renal tubules, formed by the transudation of coagulable material, and by exu- dation from and degeneration of the epithelial cells lining these tubes. The casts contract and entangle formed elements and crystals, and are finally washed out by the pressure of liquid from the glomeruli. They are nearly, if not quite, always ac- companied by albumin. Tube-casts are of prime importance in the diagnosis and prognosis of renal diseases. Small casts (from the narrow and convoluted tubules) characterize acute and superficial lesions, as a rule, while broad casts (from the straight collecting tu- bules) are more often observed in well-advanced degenerative cases. Casts are distinguished from foreign bodies by their cylindric, finger-shaped form, often rounded at one or both ends; and by their more regular contour and lesser opacity. The simplest type of tube-cast is the hyaline, which is so nearly transparent as to require a dim background for its ready detection. A few hyaline casts, with a trifling amount of albu- min, are often to be found in transient renal circulatory dis- turbances, such as may be caused by a long bicycle-ride, over- eating or overdrinking, mental or physic strain, fevers, lithemia, embolism, and ether or chloroform anesthesia. They are also seen in cases of cyanotic kidney, due to passive congestion, and occasionally in anemia, malnutrition and suboxidation, nephro- lithiasis, pyelitis, floating kidney, and even with tumors of the bladder. Jaundice may be accompanied by yellow, hyaline casts. 466 CLINIC CHEMISTRY. Chronic interstitial nephritis is manifested by the constant or intermittent occurrence of small numbers of hyaline casts, and still fewer, faintly granular ones, along with polyuria and slight albuminuria and distinctive cardiovascular changes. The band-like so-called cylindroids are similar in appear- ance and nearly equal in significance to hyaline casts, but are very much larger. Long, pale, branching, striated mucin bands are always present with excess of mucus, and hence are noted in any dense, acid, irritating urine. Mixed casts, composed of a hyaline matrix, beset with Fig. 61. Narrow Hyaline Casts. blood- or pus- cells, epithelia, nuclei, or granules, characterize acute parenchymatous or diffuse nephritis, being found here in large numbers; and also the exacerbations of chronic ne- phritis. The irregular blood-casts proper are likewise noted in renal hemorrhage from any cause, and in small numbers from infarction or marked congestion of the kidney. When retained long in the tubules the corpuscles break down into dark, rusty granules, forming, thus, rarely hemoglobin-casts. Fibrinous casts are simply blood-stained hyaline molds, and are of common occurrence in hemorrhagic nephritis. Irregular yellow-brown pseudocasts of wavy fibrin may be found in many URINE. 467 forms of hematuria, Cast-like conglomerations of pus-cells are significant of renal abscess or pyonephrosis, but one should not mistake for these groups the larger clumps due to pyelitis, pros- tatitis, or leucorrhea. Granular casts denote most often subacute or chronic parenchymatous nephritis, especially when accompanied by con- siderable albumin and dropsy. The coarser the granulations, the more acute is the disease; the finer, the more chronic. These finely granulo-hyaline casts are often observed in the same conditions as simple hyaline casts: for instance, in uric- Fig. 62. Epithelial Casts. acidemia. Coarsely granular casts have been observed in renal cysts. Brownish, blood-stained, granular casts are sometimes encountered in scurvy, hemophilia, and other blood dyscrasias and in hemorrhagic nephritis. Fatty casts are formed secondarily from granular and epi- thelial casts, and indicate always a chronic degenerative process. The fat-globules imbedded in these casts are very readily recog- nized by their glistening, highly refractive appearance. Fatty cylinders are most abundant in the large white kidney of very chronic nephritis. Irregular, cast-like conglomerations of fat- drops, accompanied at times by fatty acid needles, are some- 4C8 CLINIC CHEMISTRY. Fig, 63. Granular Casts. Fig. 64. Waxy Casts. URINE. 469 times met with in renal abscess, fracture of the long bones, and in poisoning by P, As, Sb, and iodoform. Waxy or amyloid casts appear as highly refractive, yellow- ish, often cloudy, wavy, and fluted cylinders. They are quite brittle; hence often much broken and irregular. They are at- tacked hardly at all by acetic acid, which is a further distinction from the hyaline cylinders. Some of them, when retained for a long time in the tubules, give the amyloid reaction: a ma- hogany color with a dilute solution of iodopotassic iodid, turn- ing to a dirty violet on addition of dilute H 2 S0 4 . Waxy frag- Fig. 65. False Casts. ments may be found in subacute and chronic parenchymatous nephritis and in renal amyloidosis, which last is usually accom- panied by amyloid liver and spleen. Bacterial casts in freshly passed urine are suggestive of interstitial suppurative nephritis or an ascending pyelonephri- tis. Similar groups of micrococci (zooglea) deposited on mucous threads are apt to occur in any urine that has stood for some hours, particularly in warm weather. Bacterial casts resemble somewhat pale, granular casts, and are very resistant even to strong chemic reagents. Deposits of urates on mucin bands and hyaline cylinders 470 CLINIC CHEMISTRY. give rise to yellowish, pink, or red-brown cast-like formations ("catarrhal casts"), which have at times been mistaken for granular casts. These conglomerations may consist either of amorphous urates or of calcium oxalate or the crystalline urates of sodium or ammonium. They are readily distinguished from granular casts by their solubility in warm water or in alkalies. Uratic pseudocasts are of frequent occurrence in the concen- trated urine of lithemic persons, especially infants and children. Similar concretions may be observed occasionally in any cold, dense, acid urine, with "brick-dust" deposit of acid urates. From the above brief resume it will be noted: (1) that tube-casts have general as well as local significance; (2) that no Fig. 66, Pus-corpuscles. one type is in itself pathognomonic of a single definite lesion; (3) that the various types are pathologically and clinically pro- gressive, changing with the stages of the underlying disease, according to its particular nature. CELLS. A few leucocytes are present in every urine. Any consid- erable number indicates irritation, inflammation, or ulceration of some part of the genito-urinary tract. Pus-cells are readily distinguished by their granular appearance and by their nuclei (rarely mononuclear), which if not apparent can be brought out by treating with a drop of dilute acetic acid. The nuclei are URINE. 471 often coalesced in horseshoe form, made evident by staining. Von Jaksch states that leucocytes are stained a deep mahogany- brown (glycogen reaction) by KI solution, while small round cells are stained light yellow. In the presence of alkalies pus- corpuscles are broken down into a glairy, mucus-like mass, in which only the nuclei may be visible. Albumin is always pres- ent in the supernatant liquid when there is a macroscopic de- posit of pus. In gonorrheal urethritis the pus-cells are held together in threads and bands by mucin, and are sometimes attended by spermatozoa. The purulent urine of chronic cys- titis is generally ammoniacal, except in tubercular and calculous cases. A sudden gush of greenish pus is likely to have come from a ruptured abscess or pyonephrosis. Mucus corpuscles vary in size from a pus-cell to several times larger. They are pale, rather irregular, finely granular, Fig. 67. Normal Blood-corpuscles. and non-nucleated. They are always accompanied by mucin bands. An excess of mucus is observed in irritative conditions below the kidneys. The nebecula in these cases is greatly in- creased, and the urine becomes viscid, slimy, and ropy. Red blood-corpuscles, if present, on centrifugation are thrown down in a dense, reddish layer, of a much deeper shade usually than the urates. The supernatant liquid shows a trace or more of albumin. Under the microscope the colored blood- cells are ordinarily easily recognized by their biconcave discoid form. The difference in focus between the central circle and the outer ring is shown by the separate focus of each, one ap- pearing dark when the other is light. Normal blood-corpuscles are yellow and are not arranged in rouleaux as in blood from other sources. In dense urine they become crenated. Abnor- mal blood-cells, such as have been in the urine for some time 472 CLINIC CHEMISTRY. (blood- rings or shadows, "washed-out" blood-corpuscles), are swollen, biconvex, and devoid of color and about two-thirds the size of normal cells; a few of these are commonly to be seen throughout the intervals of renal colic due to stone. Blood- casts are certain evidence of a renal origin. Epithelial cells from the genito-urinary tract differ in size and shape according to their anatomic source, the layer from which they were derived, and the reaction and density of the urine. A lining of stratified epithelium first layer flat, or squamous; middle layer cuboidal, or round; deep layer co- lumnar, or cylindric exists in the renal pelves, ureters, blad- der, urethra, vagina, and cervix of the uterus; a simple epithe- lial lining obtains in 'the uriniferous tubules, the prostate, ejaculatory ducts, Bartholinian gland, and uterine mucosa. The size of epithelia from the same site varies at different c ^^ g Fig. 68. Urinary Epithelia. times; thus, in light, slightly acid or alkaline urines the cells swell up, while in dense, acid urines they shrink. The leuco- cytes, which are practically always to be found, also shrink or swell in the same proportion, and are convenient as a standard for the measurement of epithelia with a view to determine the origin of the latter. Epithelia are distinguished from leuco- cytes by their larger size and the presence of a single nucleus usually distinct without the aid of reagents. The round or cuboidal renal cells are about a third larger than the leucocytes in the same specimen. They are highly granular, with a relatively large nucleus. The round cells from the prostate and the ureters are twice the size of pus-corpuscles. The small, brown, caudate cells from the renal pelvis are a little larger than those from the ureters, and are commonly arranged in groups like the shingles on a roof; their tails are URINE. 473 often curved and sometimes bifurcated. These cells are always accompanied by more or less blood and often by crystals. The small round cells from the deeper layer of the pelvis are often arranged in clumps and are always accompanied by pus. Epi- thelia from the calices are rarely found. They are somewhat larger than the tubule-cells and generally overlap one another, forming clumps. They have a large prominent nucleus and are seen in acute pyelitis. Epithelia from the neck of the bladder are three to five times the size of a leucocyte. They are usually round or oval, with a small, prominent nucleus. From the fundus the cells are still larger, and if from the superficial layer are flat, thin, and polygonal, and joined by their edges; thin and circular from near the ureteral orifices. Male urethral cells are one and one-half to two times as large as leucocytes, and are very irregular. They are commonly clumped with pus in threads of mucus. The round or pyriform prostatic cells may be accompanied by prostatic casts, which are simply long shreds of mucin entangling phosphates. Seminal cells are readily distinguished by the presence of spermatozoa both free and in the cell. These cells are of medium size, round in form, and highly granular, with an ill-defined nucleus. The largest cells encountered in urine are those from the vagina. They are squamous, warped, and arranged overlapping in sheets, only slightly granular, contain many bacteria, and are commonly accompanied by pus-cells. They are due to leu- corrhea, menstruation, or masturbation. Vulvar cells and cells from the glans penis are apt to take on the character of dried, jagged, epidermal scales without a nucleus and often studded with fat and dirt: the so-called smegma. Small, ciliated epithelia may come from the body of the uterus (prismatic, with ordinary vaginal cells during menstrua- tion) or the ejaculatory ducts. The cells from the female ure- thra are large and round or oval, quite similar to those from the neck of the bladder. Those from the Bartholinian glands are exactly the counterpart of the prostatic cells. Epithelia from the neck of the uterus are flat, cuboidal, and columnar, and quite irregular; they are somewhat smaller than those from the vagina. Decidual cells are large, round, polygonal, or spindle-shaped, with large nuclei and nucleoli. While a small number of epithelia (vesic, especially) may be said to represent the normal "wear and tear' 7 of the mucous membrane, large numbers indicate irritation or inflammation. Fatty degeneration of cells, except vaginal, is an indication of a chronic inflammatory condition of the part involved. If 474 CLINIC CHEMISTRY. the fat-drops have been washed out, vacuoles are left. Multiple nuclei are generally evidence of adjacent inflammation exert- ing pressure, as in the case of a perirenal or perivesic abscess. Fatty renal cells are noted, not only in subacute and chronic diffuse nephritis, but also in the fatty stage of acute nephritis and severe renal congestion. These fatty renal cells are not to be mistaken for the compound granule-cells, which are larger, round epithelia that have undergone complete fatty degenera- tion, and show no nucleus, but sometimes fatty needles. They have been observed in chronic pyelitis, cystitis, prostatitis, and urethritis; also in ulcerations and in the contents of a ruptured abscess or cysts, as well as in vaginal secretions. Chyle or fat in the urine is recognized microscopically as highly refracting globules with dark, broad borders, dissolving on the addition of ether. All urine containing any appreciable amount of blood al- ways contains wavy bands of fibrin with refractive margins. Connective-tissue shreds are made up of bundles of wavy, highly refractive fibers and fibrillae. They are found in ulceration, suppuration, hemorrhage, trauma, tumors, prostatic hyper- trophy and inflammation, renal cirrhosis, renal atrophy, and all intense inflammatory processes. Spermatozoa are found in the urine after sexual intercourse or emissions and almost constantly in the very rare condition of true spermatorrhea. Spermatozoa are about one six-hun- dredth of an inch long and consist of a flattened, oval head and a long, tapering tail. The motion of these bodies soon ceases in the urine. In spermatocystitis the head often becomes gran- ular, like a pus-corpuscle. Amyloid corpuscles from the prostate are pale, irregular, oval, or angular concentric bodies having a high refraction and often a central nucleus. They are colloid in structure, and are increased in numbers in prostatic hypertrophy. They may form the basis of prostatic concretions. Fragments of urinary tumors are occasionally found, par- ticularly papillomatous shreds and sarcoma-corpuscles. These are compact, granular bodies a trifle smaller than pus-cells, and are nearly always accompanied by large shreds of connective tissue. Cancer-cells and the pigmented cells of melanoma are rarely seen. The most common parasite found in the urine is the tri- chomonas vaginalis: a harmless habitant of the vagina in cases of leucorrhea. In the bladder it may give rise to dysuria and hematuria. It has an oval head, often nucleated, with a large tail or several flagella. It is much larger than spermatozoa. URINE. 475 BACTERIA. The flora of the urethra, according to Warren, includes the bacterium coli commune, coccobacillus liquefaciens urethras, bacillus urethras non-liquefaciens, leptothrix urethras, diplo- coccus candidus urethras, pseudogonococcus, gonococcus of Neisser, staphylococcus ureas liquefaciens, streptococcus py- ogenes, streptococcus liquefaciens urethras, sarcina urethras, smegma bacillus, tubercle bacillus, bacillus typhosus, staphylo- cocci pyogenes aureus and albus, and streptobacillus anthra- coides. Of the vesic flora, the bacterium coli commune is the most common cause of acid cystitis, gaining access to the urine in case of obstinate constipation or other bowel trouble. The urobacillus liquefaciens septicus (proteus Hauser) is pyogenic and decomposes urea, setting up ammoniacal cystitis and pye- lonephritis. The diplococcus and the staphylococcus ureas Fig. 69. Micrococcus Urese. liquefaciens (Melchior) also rapidly decompose urea; the strep- tobacillus anthracoides slowly. The staphylococci aureus and albus are common pus-producers and also decompose urea. The bacillus lactis aerogenes is responsible for most cases of pneu- maturia, in which bubbles of gas are passed with the urine. In urine that is undergoing putrefactive changes micro- cocci ureas are most constant. These appear under the micro- scope as trembling points, isolated or collected in strings. The bacterium termo, another common putrefactive micro-organism, appears as comparatively large, oblong cells, often joined in pairs or longer chains. In stale urine we often see zooglea groups of cocci: that is, masses of cocci enveloped in a color- less, gelatinous capsule. The bacillus subtilis, or hay bacillus, is a large bacillus frequently found in decomposed urine, and various actively motile vibriones are likely to gain access from the air or from unclean vessels. Leptothrix threads are some- 476 CLINIC CHEMISTRY. times seen and in large numbers may give rise to mycotic cys- titis; in such cases they may be seen in the urine as whitish pellicles with the naked eye. Yeast-cells, or saccharomyceta?, are found in acid urine, particularly in cases of diabetes mel- litus. They are distinguished from colorless blood-cells by their oval shape, irregular size, budding, and nuclei. Oidium lactis is a common mold-fungus of the acid urine, and consists of jointed stems (mycelia) and vacuolated spores (conidia). The penicillium glaucum and aspergilli are much less frequent in urine. The hypha of the latter fungi ends in a spheric or club- shaped vesicle; the hyphae of the former divide and subdivide into thread-like basidia and streigmata. Of pathogenic urinary bacteria the tubercle bacillus is most important. It is pyogenic and gives rise to acid cystitis and pyelitis. Tubercular lesions may be either primary or second- ary. The smegma bacillus resembles the tubercle bacillus in form and in reaction to the common stains; it is usually ex- cluded by treating with alcohol, which decolorizes the smegma, but not the tubercle bacillus. To detect tubercle bacilli in the urine centrifugate, wash sediment by decantation with dis- tilled water, and centrifugate again; fix sediment by heating gently over a copper or iron plate; stain with carbol-fuchsin, then decolorize in 20-per-cent. HN0 3 and again in 70-per-cent. alcohol (for at least ten minutes), and counterstain with aqueous solution of methylene blue. Tubercle bacilli are often difficult to find when present in urine, and in case of doubt some of the urine and sediment should be injected into guinea-pigs. The gonococcus is a frequent habitant of the genito- urinary tract, and is the commonest cause of suppuration in both sexes. Gonorrhea, is usually a mixed infection. Coplin's method of staining gonococci is as follows: Stain with saturated alcoholic solution of methylene blue for five to fifteen minutes, wash with water, and then stain with saturated alcoholic solu- tion of eosin for the same length of time. Wash in water, dry, and mount. The nucleus of the pus-corpuscle as well as the diplococci contained in the cells are stained blue; the proto- plasm of the cells, pink. The streptococcus pyogenes is the commonest germ of puerperal fever. The bacillus typhosus is present in at least 25 per cent, of cases of typhoid fever during convalescence. The diplobacillus of Friedlander is occasionally present in the urine, particularly during an attack of pneumonia. Other un- usual pathogenic urinary bacteria are the streptococcus ery- sipelatis, spirillum of relapsing fever, bacillus of glanders, anthrax bacillus, and bacillus of ulcerative endocarditis. PLATE VIII. TUBERCLE BACILLI IN URINARY SEDIMENT. . (After v. Jaksch.) URINE. 477 1 .2 | ;= "o j= - 1 1? | = C 5 -I - '5 2 I II Us wi* 2 * SalHI- i^| a Ji *i!llllli^i^l - - - X K =H b fan 1 1 osS-as; sisr g,g s =* gJB S ll-L 11118 Oil ll :o S WT- ^--^^ w i ojjs ^ OQ Jil 51 >H 3 c "o e 'S rt ^ S c8 % f ' "l^x'CS 5 K * I se c3 -gS^s-^Gi frSU - 1 * . . " ||||: 5 C "7 G . IH e .; ^. ~ G (BCteO^ .S .5 . rt ^ S ^ .S -3 w 3 C be a " __ 8- j|*j Iff PI *^d)Vi ^^^rt^C^ |l Iff lllll | ^llllllltll li^liLslll? g a dee napii 9 8 l&!llf -4'<3: 8 il||5>Ill 3G.ssg8 s=e Q S it !r^ ~ t. tJC*^ 111 . i-!il!fs-PJiM : . fc ^ i Isj-a H-ftB ^ "^^ s^ 60 -i s|a*S g a-fi.5 S full o 478 CLINIC CHEMISTRY. THE URINE IN THE DIAGNOSIS OF NON- URINARY DISEASES. We judge most certainly the condition of a living organ- ism by comparing its intake and its output. The urine is the chief index of metabolism in the human body, and its qualita- tive and quantitative examination furnishes evidence of the greatest practical value. SPECIFIC INFECTIONS. During the febrile stage of all fevers the urine is dimin- ished in quantity and highly acid. The sp. gr. shows a relative increase, owing to the absolute excess of urea depending on augmented tissue-waste. Uric acid is increased proportionately even more than urea, and uratic deposits are common. The excretion of chlorids and phosphates, except in spotted fever, is diminished until the beginning of convalescence. Pigmenta- tion is deepened because of hemolytic changes, and bile-pig- ment is not infrequently present, particularly in small-pox. Hemoglobinuria is indicative of decided destruction of red blood-corpuscles; it accompanies severe infections, and is a valuable premonitory sign of scarlatinal hematuria and nephri- tis. Albuminuria is observed at some time in the majority of cases of fevers generally, but is usually slight in quantity unless nephritis complicates. Peptonuria is occasionally noted, par- ticularly in pyemia and cerebro-spinal meningitis, and a trace of glucose is not uncommon. Hyaline casts are frequent, even without supervening nephritis in the event of which we find also epithelial, red blood-, leucocyte, and granular casts. Chronic pyelitis is a more frequent sequel of infectious diseases than is chronic nephritis. The special color test of typhoid fever known as Ehrlich's diazo reaction has been ranked by good authority as of equal value with Widal's agglutination test. It occurs a day or two earlier (fifth to ninth day usually) than does the serum-reaction, and serves quantitatively for prognosis, whereas the serum- reaction is said to have no prognostic significance; the diazo reaction may be absent throughout the course of very mild cases of enteric fever. This reaction is of special use in differen- tiating typhoid from simple enteritis and allied complaints. It is likewise met with in miliary tuberculosis (usually not till the third week), carcinoma, and in severe cases of measles, scarla- tina, erysipelas, and pyemia, as also in cases of ordinary phthisis PLATE IX. Fig 2 Fig. 3 CHARACTERISTIC MICROSCOPIC SEDIMENTS. Fig. i. Acute Nephritis. Fig. 3. Pyelitis. Fig. 2. Chronic Diffuse Nephritis. Fig. 4 . Cystitis. URINE. 479 which are rapidly progressing to a fatal termination. In all these instances its occurrence is chiefly an item of prognosis. The Ehrlich reaction depends upon the red color produced by the action of diazo-benzol-sulphonic acid, in the presence of excess of NH 4 OH, on an unknown chromogen in the urine of typhoid and other diseases. Two solutions are required and should be kept in a dark place. The first consists of 10 c.c. HC1 with 200 c.c. of a saturated aqueous solution of sulphanilic acid. The second is a 0.5-per-cent. aqueous solution of sodium nitrite, made as fresh as possible. The reaction between these two solutions may be represented as follows: W N + 2 ^ To apply the test mix 100 parts of the first solution with 1 part of the second, add an equal volume of urine, shake well, and allow an excess of NH 4 OH to run slowly down the side of the tube. If the reaction is positive, the foam will be colored pink and the urine crimson. The color of the foam is the most essential feature, since all febrile urines give an orange color with the test solution. If the mixture is poured into a porce- lain dish containing water, a salmon-red color is obtained when the reaction is positive, while a yellow or orange color is nega- tive. HEMIC AND CIRCULATORY DISORDERS. The relative value of the vis a tergo is the all-important factor in the causation of the urinary changes of circulatory origin. When cardiac hypertrophy exists, and compensation is maintained, there is absolute increase of both the water and the solids of the urine. Failing compensation is marked and measured by decrease of the solid ingredients and by the pres- ence of albumin and hyaline casts, both of which may be made to disappear for a time under the administration of digitalis and other cardiac tonics. Much the same picture as to the urine presents itself in the secondary cardiac dilation of valvu- lar disease, and in arteriosclerosis and the various myocardial degenerations. Concerning blood-changes proper, hematuria, apparently spontaneous, is of rather common occurrence in purpura hem- orrhagica, scurvy, and hemophilia. A pale, abundant urine, deficient in normal solids, is a feature of chlorosis and anemias. In progressive pernicious anemia indicanuria is a prominent sign. A small amount of albumin may be encountered in any of the blood dyscrasias as well as in degenerative lesions of the 480 CLINIC CHEMISTRY. ductless glands. Remembering the nucleinic origin of uric acid, a great excess of this ingredient in the urine of leukemia is not surprising. Ulcerative endocarditis and hidden pyemic foci may discover themselves first by renal infarcts, with sudden pro- nounced albuminuria and blood- and pus- casts. RESPIRATORY DISEASES. The chlorids show a reduction in all dyspneic conditions, particularly in pneumonia and capillary bronchitis. The ex- cessive excretion of chlorids following retention is a more def- inite sign of resolution than even the fall of temperature by crisis or lysis. Urea and sulphates are markedly increased ex- cept in grave cases, and the urates are enormously augmented. Albuminuria is present in nearly one-half of all cases of pneu- monia, and these yield a mortality three times as great as in non-albuminuric patients. Albumosuria or peptonuria is a distinctive feature of the absorption stage in pneumonia and pleurisy with exudation. The urine of phthisis is very variable. It is usually increased in quantity till near the fatal end. Albu- minuria is the rule, but the quantity is. slight except in amyloid renal lesions, which are comparatively rare. The urine of em- physema is also likely to contain albumin, owing to circulatory obstruction. GASTRO-INTESTINAL DISEASES. In organic disease of the stomach and intestines the urine, as a rule, is diminished in quantity, the diminution amounting to suppression at times in the various forms of cholera, in ap- pendicitis, and in acute obstruction. The reaction is frequently neutral or alkaline, with resulting precipitation of earthy phos- phates, or "phosphaturia." The normal digestive curve of acid- ity is always deepened in gastrosuccorrhea, but is absent in atrophic gastritis and cancer of the stomach. The chlorids are deficient in carcinoma ventriculi and in dilation with gastro- succorrhea. Intestinal indigestion is characterized by deposits of urates and oxalates. A trace of albumin, attributable to autointoxication, is not seldom to be found, and peptonuria is often present in ulcerative conditions. Next to pus, an excess of "indican" is the most familiar feature of pathologic urines. This indicanuria signifies, as a rule, albuminous putrefaction in the alimentary tract, and the indications for laxatives and intes- tinal antiseptics are plain. In acute or chronic intestinal ob- struction the excess of indican is apt to be enormous, and it is likewise marked in general peritonitis. Hydrothionuria nat- urally gives rise to a suspicion of fecal fistula, but the same URINE. 481 sewer-gas odor may be developed by certain micro-organisms introduced per vias naturales. * HEPATIC AND PANCREATIC LESIONS. In all liver lesions the urine is highly acid and deeply colored. Bile-pigment is commonly present in considerable amount. Urea is more or less diminished, being nearly absent and replaced by ammonia in acute yellow atrophy. Uric acid is increased, while the chlorids are diminished in direct propor- tion with ascites. Albumin is seldom noted except in cases secondary to cardiac lesions and in syphilitic, tubercular, and amyloid livers. A trace of sugar is not infrequent in liver dis- orders generally. In obstructive jaundice choluria is evident both before and after the appearance of icterus in the skin. The conjugate sulphates are much increased in obstructive jaun- dice; the total sulphates diminished in the non-obstructive form. The choluria of cholelithiasis is of distinct service in differentiating hepatic from renal colic and other abdominal pain. Leucin and tyrosin are occasionally noted in various hepatic affections as well as in defective intestinal digestion, but they are much more abundant in acute yellow atrophy. A striking character of the later stages of hepatic cirrhosis is the coincidence of a urine dark in color and light in weight: always a sign of grave import. Chronic pancreatitis is marked by polyuria, glycosuria, and lipuria. There may be albumin or glucose in the urine of pa- tients with pancreatic cysts. Lipuria is also observed in cancer of the pancreas, and diabetes mellitus may supervene. OSSEOUS, ARTICULAR, AND CONSTITUTIONAL DISEASES. The urine of acute articular rheumatism is typically py- rexial, with high color, density, and acidity; great excess of urea, sulphates, and urates; and diminished chlorids. Albu- minuria is slight and transient. The most marked feature of gouty urine is the nearly constant reduction, from retention, of uric acid and phosphates, with periodic storms of excessive excretion immediately following acute exacerbations. This condition is frequently associated with oxaluria and with chronic interstitial nephritis. In tubercular joint disease, with abscess-formation, the presence of peptonuria may aid in a correct diagnosis. In gonorrheal arthritis careful examination of the urethral secretions will usually reveal the gonococci. Rachitis and osteomalacia are both distinguished by great ex- cess of earthy phosphates; chronic articular rheumatism and 482 CLINIC CHEMISTRY. diffuse periostitis, by less marked increase. Fat in the urine is commonly observed after fracture of the long bones, and the return of the earthy phosphates to a normal daily amount, after previous excess, is a certain indication that bony union is com- plete. Glycosuria often obtains in acromegaly. The urine of lithemia is scanty, sharply acid, high colored, and uratic during the attacks. There is occasionally slight albuminuria, with cylindroids and hyaline casts. The lithemia of infants is mani- fested by a deposit of red sand on the diapers. Muscular rheu- matism is sometimes accompanied by oxaluria. In simple atrophy, or marasmus, the urine is often milky from white urates, fat, and mucus, and albumin or sugar may be present. Albumosuria has been noted particularly in sarcomatosis of the ribs, sternum, and other bones. NERVOUS DISEASES. Hysteria is noted for the large amount of watery urine which, as a rule, accompanies or follows the seizure; but, on the other hand, there may be suppression lasting for days. Tran- sient polyuria is also observed after epileptic fits, attended at times by a little albumin. In neurasthenia the urine is con- stantly deficient in normal solids. In melancholia the urine is often deficient in quantity, and of high sp. gr. Oxaluria is apt to show itself clinically by intestinal dyspepsia, lumbar aching, and nervous irritability and depression. Phosphaturia is a fre- quent accompaniment of nervous debility. In chorea we find an increase both of urea and of phosphates. Migraine is marked toward the close of the attack by an abundance of uric acid and allied products. Glycosuria is of common occurrence in medul- lary lesions. Surgical shock, particularly when due to rectal or genito-urinary operations, is likely to be joined with urinary suppression or- retention. Retention, usually with overflow, is usually present likewise in organic spinal lesions. In meningitis and other high-grade nerve-inflammations the earthy phos- phates are greatly in excess. The three forms of diabetes insipidus, mellitus, and phosphatic have already been men- tioned. SKIN AFFECTIONS. Obviously a study of the urine is not often needed in skin diseases proper, so far as concerns diagnosis, yet in seeking the primary cause we shall sometimes get valuable points concern- ing defective metabolism and autointoxication. Eczema, pso- riasis, and a number of other disorders seem, from the urine, to be forms of lithemia. Hematuria is frequent after severe burns and occurs occasionally in Raynaud's disease. URINE. 483 SURGICAL CONDITIONS. Abdominal tumors may and often do give rise by press- ure to albuminuria. The occurrence of melaninuria is nearly pathognomonic of melanotic growths. In perirenal and peri- vesic inflammation the nuclei of the cells from these sites are often multiple. Internal pus-formation in any part of the body is indicated by peptonuria, the later disappearance of which shows that the abscess has discharged externally or is encap- sulated. The resorption of hemorrhagic exudations is revealed by hemoglobinuria. A considerable relative increase of urinary nitrogen over phosphoric oxid is said to be a sign of malignancy. DIFFERENTIATION OF URINARY CALCULI. Heat a portion of the powdered concretion on platinum-foil. I. The powder burns: 1. Without a flame: Uric acid: inurexid test; no NH 3 odor on treating with KHO; over three-fourths of cases; reddish or yellow-brown and tuberculated. Ammonium urate: murexid test; strong odor of NH 3 on treating with KHO; light gray; infancy. Xanthin: yellow residue on evaporating with HN0 3 turns orange with KHO, red on warming; very rare. 2. With a flame: Cystin: transient, pale-blue flame; sharp odor; powder dissolved in ammonia yields six-sided plates on evaporation. Urostealith: steady yellow flame with odor of resin; fatty and sol- uble in alcohol or ether; soft, friable, brown or yellow. Fibrin: steady yellow flame with odor of burnt feathers; insoluble in alcohol or ether, soluble in hot KHO. II. The powder does not burn. Treat with HC1: 1. Effervesces = calcium carbonate: small, smooth, spheric, gray or bronze; very rare in humans. 2. Does not effervesce: Effervesces on heating gently with HC1 = calcium oxalate: very hard and brittle -- large, dark, rough, "mulberry" calculi, or small, smooth, rounded, dark-gray "hemp-seed" calculi; often in alternating layers with uric acid, and sometimes crusted with phosphates. Odor of NH 3 on treating with KHO = triple and earthy phosphates: soluble in acetic acid and fusible; alkaline urine; gray-white and friable. Faint or no odor of NH 3 on treating with KHO = earthy phos- phates: chalky, rounded, or irregular; alkaline urine of elderly persons. POISONS. Corrosive poisoning in general is attended by scantiness or suppression of the urine, and the same is true of arsenic and belladonna in tox"ic doses. In acute phosphorus poisoning the urine, if not suppressed, is bloody, fatty, and albuminous, and 484 CLINIC CHEMISTRY. contains crystals of leucin and tyrosin. Turpentine, cantharis, and other renal irritants; illuminating gas, arsenious vapors, coal-tar derivatives, and other corpuscle-destroying agents fre- quently give rise to hematuria or hemoglobinuria. The black- ish-green color of the urine and characteristic odor of carbolic acid are. highly suggestive of poisoning by this drug, which is not seldom the result of its free and careless topic use. Chronic mineral poisoning is characterized, as a rule, by scanty urine and deficient urinary solids. Albuminuria is fre- quent, and chronic interstitial nephritis is a not uncommon sequel. The detection of lead, mercury, arsenic, copper, etc., in the greatly concentrated and oxidized urine furnishes incon- trovertible evidence of the causa morbi. This test is most cer- tain when preceded by the administration of potassium iodid for several days. QUESTIONS ON CLINIC CHEMISTRY. 1. How may a milk have been skimmed and watered and yet show a normal sp. gr.? 2. Explain how the amount of free gas in the ureometer may be greater at first than after standing fifteen or twenty minutes. 3. Write equation for reaction between uric acid and disodic hydric phosphate. 4. Explain formation of bubbles sometimes noticed in the nitric- acid test for albumin. 5. How prove by the urine that a patient has been taking bromids or iodids? 6. Why is the appearance of leucin and tyrosin accompanied by a marked reduction of urea? 7. Why do K salts exceed Na salts, reversing the normal ratio, in urine during starvation? 8. What effect does drinking lemonade have on urinary acidity? 9. Is lithemic urine likely to be more irritating in summer or in winter? 10. What is the significance of freshly passed ammoniacal urine? 11. What object in adding HN0 3 before AgNO 3 in determining chlorids? 12. What information does the urine furnish concerning digestion? 13. A drop of urine containing globulin shows an opalescent trail when dropped into distilled water. Explain. 14. How determine the amount of acid salts in gastric juice? 15. Name five drugs which taken internally may give a color to the urine like that of blood. 16. Why does blood from the kidney render the urine smoky? 17. If one gets an albumin-like ring which disappears on heating, what is it? 18. Explain the color-changes in the copper reduction tests for sugar. 19. What are the most certain evidences of kidney disease? 20. How diagnose renal insufficiency? 21. Write equation for the alkaline fermentation of urine. QUESTIONS. 485 22. In what disease is the sp. gr. abnormally high with increased quantity of urine? Explain. 23. In what diseases are the sp. gr. and quantity of urine both at times abnormally low? Explain. 24. What is the clinic significance of indicanuria? 25. Mention five points of distinction between a sediment of urates and one of phosphates. 26. Explain the relation of the night excretion to the fact that the urine is especially acid mornings. APPENDIX. SOLUBILITY OF COMMON DEUGS AT 15 C. EXPLANATION. s. = soluble ; ins. = insoluble ; f. s., v. s., and sp. = freely, very, sparingly soluble ; aim. = almost ; mis. = miscible ; dec. = decomposed. WATEU. PAKTS. ALCOHOL. PARTS. 1 ins. 200 10 Acid, benzole 500 3 25 15 s. s. 20 V S v sp s. citric 0.75 1 100 4.5 ins g 450 2 5 tannic 6 0.6 0.7 2.5 f s f s Aloin ....... > . 60 25 Alum 10 5 ins. " burnt . . ... 20 ins. 5 28 bromid .... . , 1 5 150 carbonate ... . . 4 dec 3 1.5 iodid ... ... 1 9 valerianate . . . . v s v s 8 5 Antimony and potassium tartrate " oxid 17 ins ins. ins 1 1 Apiol . . . 6.8 50 Adstol ins. sp. Arsenic iodid .... ..... 35 10 Arsenous oxid ... 30 to 80 sp Asafetida .. ... eniuls 60$> sp. 0.3 600 v s 4 6 5 Balsam of copaiba ins. 10 " " Peru , aim. ins. 5 " Tolu aim. ins. ins v. s. g ins g g Bismuth and ammonium citrate u citrate . . ins. V 8 ins. SP ins F' ins ins. ins Bromoform . 300 v s (489) 490 APPENDIX. SOLUBILITY OF COMMON DRUGS AT 15 C. (Continued). EXPLANATION. s. = soluble; ins. = insoluble ; f. s., v. s., and sp. = freely, very, sparingly soluble; aim. = almost ; mis. = miscible ; dec. = decomposed. WATER. PARTS. ALCOHOL. PA KTS. Caffein . .... 80 0.7 ins. 1.5 s. 7 s. ins. aim. ins. 1300 aim. ins. ins. ins. v. s. 10 170 ~ 100 200 v. s. 33 1 ins. 8 aim. ins. ins. ins. ins. ins. f. s. V. S. ins. ins. v. s. 2.5 f . s. V. S. V. S. dec. sp. 70 6 3.5 v. s. s. 2 135 ins. s. V. S. s. s. ins. sp. f. s. s. 2 337 s. s. 3 14 s. s. s. s. carbonate phosphate Camphor ... " monobromated Chalk ...... Chloral hydrate Chloralamid ...... . Chloral ose Chloretone . . Chloroform Chromic oxid . . . sp. 100 70 0.5 80 s. 2 15 sp. 2.6 s. 150 ins. mis.(2i#) ins. s. ins. ins. 7 0.5 ins. s. ins. ins. 10 28 aim. ins. ins. sp. ins. Cocain hydrochlorate " sulphate . Cotarnin hydrochlorate (stypticin) Creasote . . . ........ Diabetin (levulose) . Ethyl bromid " iodid " beta- SOLUBILITY. 491 SOLUBILITY OF COMMON DKUGS AT 15 C. (Continued). EXPLANATION. s. = soluble; ins. = insoluble; f. s., v. s., and s'p. = freely, very, sparingly soluble ; aim. = almost ; mis. = miscible ; dec. = decomposed. WATER. PARTS. Ferric and ammonium citrate v. s. ins. " potassium tartrate v. s. ins. " quinin citrate s. ins. " strychnin citrate v. s. sp. chlorid v. s. v. s. citrate s. ins. hydrate ins. ins. hypophosphite sp. ins. lactate . 40 aim. ins. phosphate v. s. ins. pyrophosphate v. s. ins. sulphate 1.8 ins. tartrate v. s. ins. valerianate ins. f. s. Fluorescein s. Formaldehyd v. s. Fuchsin s. Glycerin ..... f. s. f. s. Gold and sodium chlorid . ! v. s. sp. Guaiacol , . . 85 f. s. " carbonate ins. sp. Heroin hydrochlorate s. Holocain hydrochlorate 50 6 Homatropin hydrobromate . . . ! 10 133 Hydrastin hydrochlorate f. s. f. s. Hydrastinin hydrochlorate 1 3 Hyoscin hydrobromate 4 15 Ichthyol I v. s. ins. lodin j 5000 10 lodoform ins. 80 lodol ins. 3 Kairin 6 20 Kryofin 600 f. s. Lactophenin 500 9 Lanolin mis. 2 80 Lime 750 ins. Lithium benzoate 4 12 " bromid v. s. v. s. " carbonate 80 ins. citrate 2 sp. " salicylate v. s. v. s. Losophan sp. s. Lycetol s. Lysol . f. mis. v. s. Magnesium carbonate aim. ins. ins. oxid aim. ins. ins. sulphate i 1.5 ins. Manganese dioxid ins. ins. sulphate 11 ins. ALCOHOL. PARTS. 492 APPENDIX. SOLUBILITY OF COMMON DEUGS AT 15 C. (Continued}. EXPLANATION. s. = soluble; ins. = insoluble; f. a., v. s., and sp. = freely, very, sparingly soluble ; aim. = almost ; mis. = miscible ; dec. = decomposed. WATER. PARTS. ALCOHOL. PARTS. Menthol . ... SP V S 16 3 " cy tin id . 13 15 " iodid(red) aim. ins. 130 " oxid .... ins ins ins ins Mercurol (10^ nuclein) .... s ins. ins. ins. aim. ins. ins. ins. ins. 530 s. 4 vol. 35 vol. sp. 50 Morphin acetate 12 68 24 63 " sulphate 24 702 Naphtalen . . ... ins. 15 Naphtol, beta- . 1000 75 Nosophen ins. ins. Oils, fixed ins. ins. " volatile ... . . v. sp. f. s. Orexin hydrochl orate v s V S Orthofonn ... sp ins. sp. ins. Paraldehyd ... 10 g Pelletierin tannate . 700 80 100 ins Petrolatum ....... ins ins Phenacetin 1700 20 Phenocoll hydrochlorate . 16 Phosphorus ins. 350 Physostigmin (eserin) salicylate . . . . . . 150 12 240 9 v s v. s Piperazin V. S. aim ins 30 2 3 21 " iodid 2000 v sp 2 v sp " oxid ins ins Potassium acetate ... 4 1 9 1 4 al m i ns 3 2 aim ins bitartrate 200 v sp bromid 1 6 200 1 ins chlorate 16 5 v sp 6 cyanid 2 sp SOLUBILITY. 493 SOLUBILITY OF COMMON DRUGS AT 15 C. (Continued). EXPLANATION. s. = soluble; ins. = insoluble; f. s., v. s., and sp. = freely, very, sparingly soluble ; aim. = almost ; mis. = miscible ; dec. = decomposed. WATER. PARTS. ALCOHOL. PARTS. 10 ins 4 ins. 0.5 2 6 7 5 8 18 4 aim ins 18 dec 4 SD f s op. SD tartrate ... 7 aim ins Protaro-ol (8 f /c A< r j s 75 12 niis I 100 s Quinin ... . . . . .... 1670 6 10 32 54 6 34 3 " sulphate ... . . 740 65 100 5 ins f s 2 400 30 ins 15 30 60 250 v s Salol aim ins. 10 ins V S SD 40 Scopolamin hydrobromate .... . 4 15 20 8 6 " oxid v sp ins 5 hot 2 3 30 4 v SD 1 8 v. c-p. 45 12 ins 4 72 ' borate (borax) . . 25 ins ' bromid 2 16 g 1 6 ins 1 1 100 ' chlorid 2 8 aim ins s. 1 7 v s 1 30 494 APPENDIX. SOLUBILITY OF COMMON DRUGS AT 15 C. (Concluded). EXPLANATION. s. = soluble ; ins. = insoluble ; f. s., v. s., and sp. = freely, very, sparingly soluble; aim. = almost ; mis.= miscible ; dec. = decomposed. WATER. PARTS. ALCOHOL. PARTS. Sodium hyposulphite 1.5 iodid 0.6 nitrate , 1.3 phosphate 6 pyrophosphate 12 salicylate . 1.5 sulphate 2.8 sulphite 4 sulphocarbolate 6 Strontium bromid v. s. iodid v. s. lactate 4 Strychnin sulphate 10 Sugar, cane- 0.5 " milk- 6 Sulphonal 450 Sulphur ins. Suprarenal extract f. s. Tannalbin ins. Tannigen ins. Terebene ins. Terpin hydrate 250 Thallin sulphate 7 Thiocol s. Thiol mis. Thymol 1200 Trional 320 Turpentine (rectified oil) ins. Uranium nitrate s. Urethan 1 Urotropin (formin) s. Veratrin sp. Xeroform (tribromphenol bismuth) ins. Zinc acetate 3 bromid v. s. carbonate ins. chlorid 0.5 iodid v. s. oxid ins. phosphid ins. sulphate 0.6 sulphocarbolate 5 valerianate 120 ins. 1.8 sp. ins. ins. 6 ins. sp. 150 v. s. V. S. s. 60 175 ins. 50 ins. ins. s. 1 10 100 sp. sp. s. 3 s. 0.6 sp. 3 ins. 36 v. s. ins. 1 V. S. ins. ins. ins. 5 40 ARITHMETIC CONSTANTS. 495 ARITHMETIC CONSTANTS. 1 Barrel (U. S.) =31 '/,. gallons = 119.2 liters. 1 Bushel (U. S.) = 2150.42 cubic inches = 32 quarts = 35.243 liters. 1 Calorie = 2.2 thermal units = 425.5 kilogrammeters = 425,500 gram- meters = 3077.6 foot-pounds. 1 Centimeter = V 100 meter = 0.3937 inch. 1 Cubic Centimeter = 1 / 1000 liter = 16.23 minims = 0.061 cubic inch weighs 1 gram at 4 C. 1 Cubic Foot =. 1728 cubic inches 28316.085 cubic centimeters weighs 62.32 Ibs. avoirdupois at 62 F. 1 Cubic Inch = 266 minims = 16.386 c.c. weighs 252.46 grains or 16.372 grams. 1 Cubic Meter (stere) = 1000 liters = 35.315 cubic feet. 1 Dram (Troy, or Apothecary) = 60 grains = 3.888 grams. 1 Fluidram = 60 minims = 3.696 cubic centimeters. 1 Fluidounce (imperial) = 28.4 c.c. = 1.7329 cubic inches weighs 437 V 2 grains at 62 F. 1 Fluidounce (U. S. wine measure) = 8 drams = 480 minims = 29.57 c.c. = 1.8047 cu. in. weighs 456 grains or 29.57 grams. 1 Foot = 12 inches = 144 line* = 0.30479 meter. 1 Foot-pound = 0.138 kilogrammeter. 1 Gallon (imperial) = 277.27 cubic inches = 4.543 liters weighs 10 pounds (70,000 grains). 1 Gallon (wine) = 8 pints = 231 cubic inches = 3.785 liters weighs 8.34 pounds (58,328 grains). 1 Gallon (solid) = 268.8 cubic inches. 1 Grain (Troy) = 0.0648 gram. 1 Gram = 15.4323 Troy grains = weight of 1 c.c. of water at 4 C. 1 Inch = 12 lines = 2.54 centimeters. 1 Kilogram = 1000 grams = 32.1 Troy ounces = 2.2046 avoirdupois pounds = weight of a liter of water. 1 Kilogrammeter = 7.233 foot-pounds. 1 Liter a cubic decimeter = 1000 c.c. = 33.8 fluidounces = 1.056 wine quarts = 61.027 cubic inches. 1 Meter = 3.28086 feet = 39.37043 inches = about one forty-millionth of earth's meridian. 1 Millimeter = 1000 micromillimeters = Viooo meter = 0.0393 inch (about V inch). 1 Minim = 0.0616 c.c. weighs 0.95 grain. 1 Ounce (Troy) = 480 grains = 31.1 grams. 1 Ounce (avoirdupois) = 437.5 grains = 28.35 grams. 1 Pint (imperial) = 20 fluidounces = 567.93 cubic centimeters. 1 Pint (U. S. wine) = 16 fluidounces = 473.179 cubic centimeters. 1 Pound (Troy) = 12 ounces = 5760 grains = 0.37324 kilogram. 1 Pound (avoirdupois) = 16 ounces = 7000 grains = 0.45359 kilogram. 1 Quart (imperial) = 40 fluidounces = 69.97 cubic inches = 1.1358 liters. 1 Quart (wine measure) = 32 fluidounces = 58.3 cubic inches = 0.9463 liter. 1 Square Foot = 144 square inches = 0.0929 square meter. 1 Square Meter = 10.7641 square feet. 1 Thermal Unit = 0.45 calorie = 1390 foot-pounds = 0.695 foot-ton. 1 Ton (avoirdupois) = 2000 pounds = 29167 Troy ounces = 907.2 kilo- grams. 496 APPENDIX. 1 Tonneau = 1,000,000 grams = 1000 kilos = 2204.6 avoirdupois pounds. 1 Yard = 3 feet 36 inches = 0.9144 meter. EQUATIONS OF MANUFACTURING CHEMISTRY. Aluminum. Chlorid 4A1 2 O 3 + 12C1 2 + 3C 2 (at red heat) =4A1,C1 8 + 6CO, Hydrate K,A1 2 (S0 4 ) 4 .24H 2 O + Na a C0 3 = A1 2 (HO) 6 + Na 2 SO~ 4 + K 2 SO 4 + CO., + 2H 2 S0 4 + 16H 2 O + 3H 2 Potash Alum H 2 Al 2 Si 2 O 8 (shale) + 3HJ3O 4 (hot) +K,S0 4 = Al a - K 2 (S0 4 ) 4 + 4H 2 + 2Si0 2 Sulphate AI 2 (HO) + 3H 2 S0 4 = A1 2 (SO 4 ) 3 + 6H 2 Ammonium. Ammonia (for me- dicinal purposes) .2NH 4 C1 + Ca(HO) 2 = CaCl, + 2NH 3 + 2H 2 Bromid NH 4 OH + HBr = NH 4 Br +~ H 2 O Carbonate 2(NH 4 ) 2 SO 4 + 2CaC0 3 (heated in iron retort) = NH 4 HC0 3 .NH 4 NH.,CO 2 (official carbonate) + NH 3 + H 2 + 2CaS0 4 Chlorid NH 4 OH (ammoniacal water from gas-works) + CaO = NH 3 -k Ca ( HO ) 2 . NH 3 + HC1 = NH 4 C1 lodid NH 4 OH + HI = NH 4 I + H 2 Nitrate HNO 8 + NH 4 HO = NH 4 N0 3 + H 2 O Sulphate 2NH 4 HO (ammoniacal gas liquor) + H 2 S0 4 = (NH 4 ) 2 S0 4 + 2H 2 Antimonium. Chlorid Sb 2 S 3 + 6HC1 = 2SbCl 3 (solution) + 3H 2 S Oxid 4SbCl 3 .5Sb 4 O 6 + 6Na.,C0 3 = 6Sb 4 O + 12NaCl + 6C0 2 Oxy chlorid 24SbCl, + 30H 2 O = 4SbCl 3 .5Sb 4 O 6 + 60HC1 Oxysulphid 2Sb 2 S 3 + 4NaHO = NaSb0 2 + 3NaSbS 2 + 2H..O Tartrate of Anti- mony and Potas- sium 4KHC 4 H 4 6 + Sb 4 8 = 4KSbOC 4 H 4 O 6 + 2H 2 O Arsenum. lodid As + I, (rubbed together and sublimated) = AsI 3 Oxid As 2 (ores containing As) + O 3 (roasted in air) = As 2 3 Barium. Chlorid BaS0 4 + 4C (fusing) = BaS + 4CO. BaS + 2HC1 = BaCl 2 + H 2 S Hydrate .BaC0 3 (heated in current of water) + H 2 = Ba- (H0) 2 + C0 2 Nitrate BaC0 3 + 2HNO 3 = Ba(NO 3 ) 2 + C0 2 + H 2 Oxids Ba(NO 3 ) 2 (heated in iron crucible till red fumes cease) = BaO + N 2 O 5 BaO + O (heating in a stream of dry air or at 450 C.) =BaO 2 Bismuth. Subcarbonate 2Bi(N0 3 ) 3 + Na 2 CO 3 + 3H.O = (BiO),C0 3 .H 2 O + 4HNO 3 + 2NaN0 3 Subnitrate Bi(N0 3 ) 3 + 2H 2 (4 parts cold, then 21 boiling) = BiON0 3 .H 2 + 2HNO 3 Boron. Trioxid 2H 3 BO 3 (heated to redness) = B 2 3 + 3H,0 EQUATIONS. 497 Calcium. Bromid 2HBr + CaC0 3 = CaBr 2 + CO 2 + H 2 O Cm-bid CaO + 30 (heated in electric furnace) = CaC 2 + CO ( arbonate Na 2 CO 3 + CaCl 2 = CaCO 3 + 2NaCl ( 'hlorid 2HC1 + CaCOs (marble) = CaCl 2 + CO 2 + H 2 Hypochlorite Ca(HO) 2 + CJ 2 = CaOCl 2 + H 2 O Hypophosphite . . . . 3Ca(HO)o + 2P 4 -f OH 2 (warmed to 40) =3Ca- (H 2 P0 2 ) 2 +2PH 3 Oxid CaC0 3 (burned) CaO + CO 2 Phosphate 3CaCl + 2NH 4 OH + 2Na 2 HPO 4 .12H.,0:=Ca 3 (PO 4 ) 2 + 2NH 4 C1 + 4NaCl + 26H 2 O Sulphid CaSO 4 + 2C (charcoal heated) = CaS -f 2CO 2 Carbon. Dioxid CaCO, (marble-dust) + 2HC1 = CaCl 2 -f H 2 + C0 2 Disulphid C (charcoal) + S 2 (heat to redness) = CS 2 Cerium. Oxalate Ce 2 Cl 6 + 3(NH 4 ) a CA = Ce,(C 2 O 4 ) 3 + 6NH 4 C1 Chromium. Sesquioxid K 2 Cr,O 7 + S (heat) = K,S0 4 + Cr 2 O 3 Trioxid K 2 Cr 2 7 + 2H 2 S0 4 = 2Cr0 3 + 2KHSO 4 + H 2 O Copper. Arsenite CuSO 4 + KH 2 As0 3 = CuHAsO 3 + KHSO 4 Nitrate 3Cu + 8HNO 3 = 3Cu(N0 3 ) 2 + N 2 O 2 + 4H 2 O Sulphate Cu + 2H 2 SO 4 = CuSO 4 + S0 2 + 2H 2 O Gold. Chlorid Au + C1 3 (nitrohydrochloric acid) = AuCl 3 Hydrogen. Arsenate As a O 8 + 2H 2 O + 2HNO 3 = 2H 3 As0 4 + N 2 O 3 Bromid 3KBr -f- H 3 PO 4 (heated together) = 3HBr + K 3 P0 4 Chlorid 2NaCl + H.,S0 4 = Na 2 SO 4 + 2HC1 Cyanid K 4 Fe(CN) 8 + 5H,SO 4 = 6HCN + FeSO 4 + 4KHSO 4 Dioxid Ba0 2 + 2HF = H 2 O 2 + BaF 2 Fluorid CaF 2 -f H 2 SO 4 = CaSO 4 + 2HF lodid 2I 2 + 2H,S + H,O 4HI + S 2 + H 2 O N it rate KNO 3 + H,SO 4 = HNO + KHSO 4 Orthoborate Na 2 B 4 7 + 2HC1 + 5H.,0 = 4H 3 BO 3 + 2NaCl Phosphate 3P + 5HN0 3 + 2H 2 = 3H 8 P0 4 -f 5NO Salicylate NaC 7 H O 3 + HC1 = HC 7 ILO, + NaCl Sulphate 2S0 2 + N 2 O 4 + 2H,O = 2H 2 SO 4 + N 2 O 2 Sulphid FeS + HS0 4 = FeSO 4 + H 2 S Sulphite SO 2 + H 2 O = H 2 SO 3 Iron. Carbonate Na 2 C0 3 + FeSO 4 = FeCO 3 + Na 2 SO 4 Chlorids Fe + 2HC1 = FeCl 2 + H 2 . Fe 2 O 3 + 6HC1 = Fe 2 CL + 3H 2 O Hydrate Fe 2 Cl 6 + ONH 4 OH = Fe 2 (OH) fl + 6NH 4 C1 lodid 2I 2 + Fe 2 (filings in warm water) = 2FeI 2 Nitrate Fe 2 (OH) + 6HNO, = 6H 2 O + Fe a (NO,) e Sulphates Fe + H 2 SO 4 (dilute) = FeS0 4 + H 2 . Fe.O, + 3H 2 - S0 4 = Fe 2 (S0 4 ) 3 + 3H 2 Sulphid Fe + S 2 (fused together) = FeS 2 Lead. Acetate PbO + 2HC 2 H.,O 2 = Pb(C 2 H 3 O 2 ) 2 + H a O 32 498 APPENDIX. Lead (Concluded). Basic Carbonate . . .Dutch method: 3Pb + 2 (air) + 2C(X (manure or tan-bark) + 2HC 2 H 3 2 (vapors) Pb 2 (OH) 2 .- 2C 2 H 3 2 + 2C0 2 + H 2 + O + Pb = (PbC0 3 ),.Pb(HO) 2 + 2HC 2 H 3 2 French method: 3PbO + 3Pb(C 2 H 8 O 8 ) a = Pb 3 0(C 2 - H 3 2 ) 4 H-Pb 3 O,(CoH 3 O 2 ) 2 . These and 2CO, + H 2 (PbC0 3 ) 2 Pb(HO) 2 + 3Pb(C 2 H 3 2 ) 2 lodid Pb(NO 3 ) 2 + 2KI = PbI 2 + 2KNO 3 Monoxid PbC0 3 (heated to low redness) = PbO -f C0 2 Nitrate PbO + 2HN0 3 = Pb(N0 3 ) 2 + H 2 Oleate 3PbO + 3H 2 O + 2C 3 H 5 (C 18 H 33 2 ) 3 (olive-oil) = 2C 3 - H 5 (HO) 3 + 3Pb(C ]8 H 33 2 ) 2 Subacetate PbO + Pb(C 2 H 3 2 ) 2 = Pb 2 O(C 2 H 3 O 2 ) 2 Lithium. Bromid LLC0 3 + 2HBr = 2LiBr + C0 2 + H 2 O Carbonate Li 4 SiO 4 (lepidolite) + H,S0 4 + H,0 + Ca(HO) 2 4LiOH, etc. 4LiOH + 2 (NH 4 ) 2 C0 3 = 2Li 2 C0 3 + 4NH 4 OH Chlorid Li 2 CO 3 + 2HC1 = 2LiCl + C0 2 + H,O Citrate 3Li 2 C0 3 + 2H 3 C v; H 5 O 7 = 2Li 3 C 6 H 5 O 7 + 3H 2 O + 3CO 2 Salicylate Li a CO, + 2HC 7 H 5 O 3 = 2LiC 7 H 5 3 + H 2 + CO, Magnesium. Carbonate 5MgSO 4 + 5Na 2 C0 3 + 6H 2 O = (MgCO,) 4 .Mg- (HO) 2 .5H 2 O (heavy or official carbonate) + 5Na 2 SO 4 + C0 2 Citrate 3(MgC0 3 ) 4 .Mg(HO) 2 .3H 2 O + 10H 3 C 6 H 5 O 7 + 49ILO = 5Mg 3 (C 6 H B 7 )2.14H 2 O + 12C0 2 (more CO 2 is produced by dropping in crystals of KHCO 3 just before corking and wiring). Hydrate MgSO 4 + 2NaHO = Mg (HO) 2 + Na 2 SO 4 Oxid (MgC0 3 ) 4 .Mg(HO)o.5H 2 O (ignited) =5MgO (heavy, or official) + 6H 2 + 4CO 2 Sulphate MgC0 3 + H 2 SO 4 = MgS0 4 + CO 2 + H 2 Manganese. Sulphate MnO 2 + H 2 S0 4 = MnSO 4 + H 2 + O Mercury. Ammoniated HgCl 2 + 2NH 4 HO = NH 2 HgCl + NH 4 C1 + 2H.,O Chlorids Hg.,SO 4 + 2NaCl = Hg 2 Cl 2 + Na 2 SO 4 HgSO 4 + 2NaCl (sublime) = HgCl 2 + Na 2 SO 4 Cyanid HgO -f 2HCN = Hg(CN) 2 + H 2 lodids Hg 2 (N0 3 ) 2 + 2KI = Hg 2 I 2 + 2KNO 3 HgCl 2 + 2KI = HgI 2 + 2KC1 Nitrate HgO (red) + 2HNO 3 + H 2 = Hg(N0 3 ) 2 + 2H..O Oxid HgCl 2 + 2NaHO = HgO (yellow) + 2NaCl + H 2 O Subsulphate 3Hg + H 2 SO 4 + HN0 3 + H 2 = Hg(HgO) 2 S0 4 , etc. Sulphate Hg + 2H 2 S0 4 = HgS0 4 + S0 2 + 2H,O Nitrogen. Ammonia (NH 4 ) 2 SO 4 + Ca(HO) 2 ==CaSO 4 + 2NH 3 + 2H.O Dioxid 3Cu + 8HNO 3 = 3Cu (NO S ) 2 + N 2 2 + 4H 2 O Monoxid NH 4 NO ;J (heated) = N 2 O + 2H 2 O Platinum. Chlorid Pt + 2C1 2 (aqua regia) = PtCl 4 Potassium. Acetate K 2 C0 3 + 2HC 2 H,O 2 = 2KC 2 H,O 2 + H.,0 + CO 2 Arsenite As 2 3 + 2KHCO 3 + H 2 = 2KH 2 As0 3 + 2CO 2 EQUATIONS. 499 Potassium (Concluded). Bicarbonate K 2 CO 3 + CO 2 + H 2 O = 2KHCO 3 Broinid FeBr 2 + K 2 CO 3 = 2KBr + FeCO 3 Chlorate OCa(HO) a + GCI, = 5CaCl 2 + Ca(C10 3 ), + 6H 2 O Ca(ClO,) 2 + 2KC1 = 2KC1O 3 + CaCl, Chlorid K 2 C0 3 + 2HC1 = 2KC1 + H 2 + C0 2 Chromate K,Cr,O 7 + K 2 CO 3 = 2K 2 CrO 4 + CO, Cyanid K 4 Fe(CN) 6 + K,C0 8 = 5KCN + KCNO + C0 2 Dichromate 2K 2 CrO 4 + H 2 S0 4 = K,Cr,0 T + K 2 SO 4 + H,0 Ferrocyanid 40 + 2N (animal scrap) + K 2 CO 3 = 2KCN + SCO 6KCN + FeS = K 4 Fe(CN) 6 + K 2 S Hydrate K.CO, + Ca (HO) , = 2KHO + CaCO 3 Hypophosphite . . . .Ca(H 2 P0 2 ) 2 + K,CO 3 = 2KH 2 PO, + CaCO, lodid Fe 2 I 6 + 3K,CO + 3H..O = 6KI + 3CO 2 + Fe 2 (HO) 8 6KOH + 31., = SKI + KIO, + 3H 2 O Nitrate NaNO 3 + KC1 = KN0 3 + NaCl Permanganate .... 3K 2 Mn0 4 + 2C0 2 = K 2 Mn 2 8 + Mn0 2 + 2K 2 CO 3 Sulphate 2KN0 3 + H 2 S0 4 = 2HN0 3 + K 2 SO 4 Tartrate of K and Na 2KHC 4 H 4 + Na 2 C0 3 = 2KNaC 4 H 4 O 6 + CO 2 + H 2 Silver. Broinid AgNO 3 + KBr = AgBr + KNO, lodid AgN0 3 + KI = Agl + KN0 3 Nitrate 3Ag + 4HNO 3 = 3AgN0 3 + 2H 2 O + NO Oxid 2AgNO, + 2NaHO = Ag 2 + 2NaNO 3 + H 2 Sodium. Acetate NaHCO 3 + HC,H 3 2 = NaC,H 3 0, + CO 2 + H 2 Benzoate HC 7 H 5 2 + NaHCO 3 = NaC 7 H 5 O 2 + CO 2 + H 2 O Bicarbonate Na 2 CO 3 + CO a + H-.O = 2NaHCO 3 Bisulphite Na 2 CO 3 + 2SO 2 + H,0 = 2NaHSO 3 + C0 2 Bromid FeBr, + Na 2 C0 3 = FeC0 3 + 2NaBr Carbonate Leblanc process : NaCl + H n S0 4 = NaHSO 4 + HC1 NaHS0 4 + NaCl = Na 2 S0 4 + HC1 Na 2 S0 4 + 4C = Na 2 S + 4CO Na 2 S + CaC0 3 = Na 2 CO 3 + CaS Solvay's ammonia-soda process : NaCl + NH 3 + CO 2 + H 2 = NaHCO 3 + NH 4 C1. 2NaHC0 3 (heated) = Na 2 CO 3 + CO 2 + H 2 O Hydrate Na 2 C0 3 + Ca(HO) 2 = 2NaHO + CaC0 3 Hypochlorite Ca(ClO)o + CaCl 2 + 2Na 2 CO 3 = 2NaC10 + 2NaCl + 2CaCO 3 Hypophosphite . . . .Na 2 C0 3 + Ca(PH 2 2 ) 2 =:2NaPH 2 O 2 + CaCO 3 lodid 6NaHO + 3I 2 = 5NaI + NalO 3 + 3H.O Nitrite NaN0 3 + Pb (heat in Fe vessel) = NaNO 2 + PbO Phosphate Na 2 CO 3 + H 3 PO 4 (till faintly alkaline) = Na 2 HP0 4 + C0 2 + H 2 Pyrophosphate . . . .2Na 2 HPO 4 (heated to 250) =Na,PA + H 2 O Salicylate NaHO + HC 7 H 5 3 = NaC 7 H 5 O 3 + H 2 Silicate 4Si0 2 + Na 2 CO 3 -f C (fused together) = Na 2 Si 4 O 9 + C0 2 + C Sulphite 2NaHS0 3 + Na 2 CQ, = 2Na 2 SO 3 + CO 2 + H 2 Sulphocarbolate . . . Na 2 CO 3 + 2C 6 H 3 HSO 3 = 2NaC c H 4 HS0 3 + H 2 O + CO 2 Thiosulphate ("Hy- posulphite") .... Na 2 SO 3 + S (boiled together) = Na,S 2 O 3 500 APPENDIX. Strontium. Bromid SrCO 3 + 2HBr = SrBr, -f CO, + H.O lodid SrC0 3 + 2HI = SrI 2 + CO, + H 2 O Lactate 2HC 3 H 5 O 3 + SrCO 3 = Sr(C 3 H B O 8 ) 2 + H 2 + C0 2 Nitrate SrCO 3 + 2HN0 3 (dilute) = Sr(NO 3 ) 2 + H 2 + CO, Sulphur. Dioxid S 2 + 20 2 (burn) = 2SO 2 Trioxid . 2SO 2 + 2 (with aid of red-hot Pt sponge) = 2SO 3 Tin. Chlorids Sn + 2HC1 (hot) = SnCl 2 + H 2 Sn + 2HgCl 2 (distilled together) = SnCl 4 -f Hg 2 Zinc. Acetate ZnO + 2HC 2 H 3 O 2 =rZn(C 2 H 3 O 2 ) 2 + H 2 Bromid Zn + Br 2 + H 2 O (warmed gently) = ZnBr a + H 2 O Carbonate 5(ZnSO 4 .7H 2 O) + 5(Na 2 CO 3 .10H.,O) = 2ZnCO 3 .- 3Zn(HO), (basic carbonate) + 5Na 2 S0 4 + 3C0 2 + 82H 2 Chlorid ZnO + 2HC1 = ZnCl, -f H 2 lodid Zn + I 2 (heated together) ZnI 2 Oxid 2ZnC0 3 .3Zn(HO) 2 (basic carbonate heated to low redness) = 5ZnO + 2C0 2 + 3H 2 Phosphid 3Zn 2 (powdered and heated) + P 4 (vapor) = 2Zn 3 P 2 Sulphate ZnO + H 2 S0 4 = ZnS0 4 + H 2 Valerianate ZnSO 4 + 2NaC B H 9 0, = Zn(C 8 H O,), _j_ Na 2 SO 4 ORES, ROCKS, AND MINERALS. Aluminum: Corundum or adamant spar, A1 2 O 3 (emery, granular; ruby, amethyst, and sapphire, crystalline) ; spinelle, MgO -f- A1 2 O 3 ; dia- spore, A1 2 2 (HO) 2 ; bauxite, A1 2 O 2 (HO) 4 + Fe 2 O 3 ; gibbsite, A1 2 (HO); cryolite, Al 2 F 6 .6NaF; alunite, H 8 KA1 3 S,0 14 ; turquoise, H 5 A1 2 P0 8 ; sili- cated rocks, such as kaolin or porcelain clay, H 4 Al 2 Si;,09; rotten-stone (with organic matter), slate, marl, basalt, granite or laminated talc, hornblende, emerald, aluminum garnet; topaz, Al 2 ALSiO 4 FHO; and feld- spar (silicates of Al and K, or Ca and Na) as orthoclase, KAlSi 3 O s ; and albite, NaAlSi 8 O 8 . Ammonium: Mascagnite, (NH 4 ).,S04. Antimony: Stibnite, Sb 2 S 3 ; senarmonite (octahedra) and valentin- ite (rhombic prisms) of Sb 2 O 3 . Arsenic: White arsenic, As 2 3 ; orpiment, As 2 S 3 ; realgar, As;,S 2 ; arsenical iron, FeAs 2 ; arsenical pyrites or mispickel, FeAs 2 FeS 2 . Barium: Heavy spar, BaSO^; witherite, BaCO 3 ; barytocelestite^ (BaSrCa)(S0 4 ) 3 ; barytocalcite, (BaCa) (CO B ),; psilomelane, MnBaO., + Mn0 2 . Beryllium: Beryl, 3BeSi0 3 , Al 2 (Si0 3 ) 3 (green = emerald; bluish green = aquam arine ); phenacite, Be 2 SiO 4 ; chrysoberyl, BeO, A1 2 O 3 . Bismuth: Bismuthite, Bi 2 S 3 ; bismuth-ocher, Bi 2 O 3 . Boron: Borax, Na 2 B 4 7 .10H 2 O; boric acid, H 3 B0 3 ; borocalcite, CaB 4 O 7 .4H 2 O; boronatrocajcite, Na 2 B 4 7 , 2CaB 4 O 7 .18H 2 O. Cadmium: Greenockite, CdS chiefly. Calcium: Carbonate, CaCO 3 (limestone, marble, chalk, calcite, ar- ragonite, coral, marl, shells); dolomite, MgCO 3 , CaCO 3 ; fluorspar, CaF 2 ; anhydrite, CaSO 4 ; selenite (crystalline) and alabaster or gypsum, CaSO 4 .- ORES. 501 2H 2 0; sombrerite, Ca 3 (PO 4 ) 2 ; apatite (phosphorite), Ca 3 (PO 4 ) 2 , CaCl 2 ; osteolite, Ca 3 (P0 4 ) 2 , CaF 2 ; nearly all silicated rocks. Cerium: Cerite, H 3 (Ce, La, Di) 3 (Ca, Fe)Si 3 O 12 . Cesium: Pollux or pollucite, H 2 Cs 4 Al 4 Si 9 O 27 . Chromium: Chromite or chrome-iron ore, FeO, Cr.,O 3 ; crocoisite, PbCrO 4 . Cobalt: Linneite, Co 3 S 4 ; tin-white cobalt, CoAs 2 ; cobaltite or cobalt-glance, CoAs 2 ,CoS 2 ; cobalt-bloom, Co 3 (As0 4 ) 2 ; smaltite or speiss- cobalt, (CoFeNi)As,; erythrite, Co 3 As 2 O 8 .8H 2 O. Copper: Red copper ore or cuprite, Cu 2 O; black oxid, CuO; copper glance or chalcocite, Cu 2 S; malachite, CuCO 3 ,Cu(HO) 2 ; azurite, (CuCO 3 ) 2 ,- Cu(HO) 2 ; copper pyrites (bornite, chalcopyrite), Cu 2 FeS 2 or Cu 2 S.Fe 2 S 3 ; chalcanthet, CuSO 4 ; libethenite, HCu 2 P0 5 . Gold: Electrum (gold mixed with more than 36 per cent, of silver). Iron: Iron pyrites ("fool's gold") or coal brasses, FeS 2 ; red hematite or specular iron ore, Fe 2 O 3 ; magnetite or lodestone, Fe :5 O 4 ; lintonite or brown hematite, Fe 2 (HO) 6 ; siderite or spathic ore, FeC0 3 ; wolframite, FeMnWO 4 ; vivianite, H 10 Fe 3 P 2 O 10 ; arsenopyrite (sulpharsen- ite) ; pyrrhotite, Fe s S u . Lead: Galena, PbS; cerussite, PbC0 3 ; anglesite, PbSO 4 ; wulfenite, PbMo0 4 ; pyromorphite, Pb 3 (PO 4 ) 2 ; crocoisite, PbCrO 4 ; cotunite, PbCl 2 . Lithium: Petalite, LiAlSi 4 O 10 ; spodumene, LiAlSi 2 O 6 ; lepidolite, HKLiAl 2 Si 3 10 F. Magnesium: Magnesite, MgCO 3 ; dolomite, MgCO 3 ,CaCO 3 ; carnallite, KCl.MgCl 2 .6H 2 O; kieserite, MgSO 4 .H 2 O; spinel, MgAl 2 O 4 ; silicates: talc (soapstone), H 2 Mg 3 Si 4 O 12 ; potstone, asbestos (earth-flax), meerschaum (seprolite), steatite, rensellaerite, serpentine, and enstatite. Manganese: Pyrolusite, Mn0 2 ; psilomelane, H 4 MnO 8 ; braunite, Mn 2 O 3 ; manganite, Mn 2 O 3 H-H 2 O; hausmannite, Mn 3 O 4 ; manganese spar or rhodochrosite, MnCO 3 ; manganese blende, MnS; haverite, MnS 2 ; wad or bog manganese (impure peroxid in clay). Mercury: Cinnabar, HgS; horn quicksilver, Hg 2 Cl 2 + HgJ 2 ; nat- ural amalgam, HgAg. Molybdenum: Molybdenite, MoS.>; wulfenite, PbMoO 4 ; trioxid, Mo0 3 . Nickel: Garnierite or genthite, H 2 (NiMg)SiO + Ag; magnetic py- rites or nickeliferous pyrrhotite (Fe, Ni, and S) ; millerite, NiS; nic- colite or copper nickel, NiAs; bunsenite, NiO. Potassium: Niter. KNO 3 ; carnallite, MgCl 2 ,KClj kainite, K 2 SO 4 ,- MgSO 4 ,MgC! 2 .5H 2 0; schoenite, K 1 SO 4 ,2MgSO i .6H 2 O; sylvite, KClj sili- cates (potash-feldspar, granite, syenite, gneiss, micaceous schist). Silicon: Silica, SiO 2 : rock crystal or quartz (crystalline tripoli, bath-brick, sandstone, amethyst, carnelian), tridimite (crystalline), chal- cedony (amorphous agate, jasper, flint), opal and geyserite (hydrated oxids), silicified wood and kicselguhr (diatomaceous earth); silicated rocks (clays, slates, feldspars, mica, meerschaum, serpentine, porphyry, basalt, asbestos, granite, gneiss, syenite, pumice, tourmaline, pyroxene, amphibole, etc.). Silver: Argentite or silver glance, Ag 2 S (nearly always with galena); horn silver, AgCl; iodid and bromid of silver; proustite, Ag 3 AsS 3 ; pyrargyrite (with Sb 2 S 3 ) ; tellurid (with Te). Sodium : Crude deposits of NaN0 3 in dry regions of South America. Rock-salt, NaCl; Chili saltpeter, NaNO 3 ; albite, NaAlSi 3 8 ; cryolite, Al 2 F B ,6NaF; thenardite, Na 2 SO 4 ; mirabilite, Na 2 SO 4 .10H 2 0. Strontium: Strontianite, SrCO 3 ; celestine or celestite, SrSO 4 . 502 APPENDIX. Tin: Cassitcrite or tin-stone, Sn0 2 (vein- or mine- tin and stream- tin) ; sulphid. Uranium: Uranite or pitch-blende, U 3 8 . Zinc: Zinc-blende or sphalerite, ZnS; calamine, H 2 Zn 2 Si0 5 ; smith- sonite, ZnC0 3 ; zincite or red oxid, ZnO; franklinite, (FeMnZn) (FeMn) 2 O 4 . POPULAR AND ALCHEMIC NAMES. A. C. E. Anesthetic mixture of 1 volume of absolute alcohol, 2 volumes of chloroform, and 3 volumes of pure ether. After-damp. Carbon dioxid in mines following fire-damp explosions. Aich's Metal. Alloy of Fe and Zn used for casting cannon. Algaroth Powder. Antimony oxychlorid, SbOCl. Alkermes Mineral. Sulphureted antimony, Sb 2 S 3 . Alleluia. Wood-sorrel, Oxalis acetosella. Alum Lake. Commercial sulphate, A1 2 (SO 4 ) 3 18H 2 0. Alum Silver. A strong, light alloy used in some parts of chemic apparatus. Amidon. Starch. Antichlor. Sodium thiosulphate, or "hyposulphite," used in re- moving excess of Cl in bleaching operations. Antifebrin. Trade name of acetanilid. Antifriction Metal. Any alloy having a low coefficient of friction; hence used for bearing surfaces; Babbitt's metal is an example. Apple-oil. Amyl valerianate. Aqua Fortis. Crude nitric acid. Aqua Regia. Nitromuriatic acid. Aqua Reginse. Nitrosulphuric acid; used to dissolve silver. Aqua Vitae. Brandy. Aquila Alba. Old name for calomel. Argentum Vivum. Mercury. Argols. Crude cream of tartar from wine-casks. Azote. Nitrogen. Azotic Acid. Nitric acid. Baldwin's Phosphorus. Calcium nitrate: heated and exposed to sunshine, is luminous in the dark. Balsam of Soap. Soap liniment. Barilla. Ashes of sea-plants. Bengal Fires. Red: Powdered shellac, 1; Sr(N0 3 ) 2 , 5; powdered Mg, 25 parts. Green: Powdered shellac, 1; Ba(NO 3 ) 2 , 5; powdered Mg, 25 parts. Berlin Red. Colcothar, or ferric oxid. Bitter Salts. Epsom or English salts, MgS0 4 . Bittern. Mother-liquor remaining after evaporation and crystalliza- tion of NaCl from sea-water. Black Antimony. Antimony trisulphid, Sb 2 S 3 . Black Ash. Impure Na 2 C0 3 mixed with carbon. Black Drop. Guttse nigrse; vinegar of opium. Black Flux. A mixture of C and K 2 C0 3 made by igniting cream of tartar with one-half its weight of niter. Black Lead. Plumbago, graphite; used for lead-pencils. Black Wash. A mixture of calomel and lime-water. Blaud's Pill. Ferrous carbonate with an alkaline sulphate. Bleaching Powder. A mixture of calcium chlorid and hypochlorite. GLOSSARY. 503 Blende. Various native sulphids. Blister Copper. Crude copper obtained by roasting a mixture of Cu 2 O and Cu 2 S. Blondine. Hydrogen peroxid for bleaching hair. Blue Mass. Mercurial pill. Blue Ointment. Mercurial ointment. Blue-stone, or Blue Vitriol. Cupric sulphate, Roman vitriol. Bole. Soft clay colored red by ferric oxid. Bone-ash, or Bone-black. Impure Ca 3 (P0 4 ) 2 , from charring of bones. Bone-phosphate. Calcium phosphate, Ca 3 (PO 4 ) 2 . Borax. Sodium tetraborate, Na 2 B 4 O 7 . Brimstone. Roll sulphur. British Gum. Dextrin. Brunswick Green. Oxychlorid of copper. Burnett's Disinfecting Fluid. Solution of zinc chlorid (205 to 230 gr. per oz.). Butter of Antimony, Bismuth, or Zinc. The chlorids of these metals. Butter of Paraffin. Petrolatum. Calcimine. A wash for walls and ceilings, made of whiting, glue, and water, and often tinted. Calcined Magnesia. MgO from burning of MgCO 3 . Calomel. Mercurous or mild chlorid of mercury. Camphene. Oil of turpentine. Camphoid. A mixture of 1 part of pyroxylon and 20 each of cam- phor and absolute alcohol. Canada Pitch. Hemlock-pitch from hemlock-spruce, Abies Cana- densis. Caput Mortuum. Impure Fe 2 O 3 left after igniting FeS 2 or FeS0 4 . Caramel. Burnt sugar. Carbolic Acid. Phenyl hydrate, or phenol, C 6 H 5 HO. Carborundum. An extremely hard polishing substance made by fusing together, in an electric furnace, sand, salt, sawdust, and carbon. Chameleon Mineral. Potassium permanganate or manganate. Chinosol. A soluble, crystalline, yellow powder of the quinolin group; disinfectant and deodorant. Chloralum. A disinfectant composed of a solution of impure A1 2 C1 . Chloric Ether. Alcoholic solution of CHC1 3 . Chloros. A disinfectant liquid containing 10 per cent, of available Cl. Choke-damp. CO, in mines. Chrome-green. A mixture of chrome-yellow and Prussian blue, or CrA- Chromeisen. A tough alloy of Fe and Cr. Chrome-vermilion. Lead dichromate, PbCr 2 O 7 Chrome-yellow. Lead chromate, PbCrO 4 . Citrine Ointment. Mercuric-nitrate ointment. Clemens's Solution. Solution of arsenate and bromid of K. Colcothar. Rouge, crocus, Fe 2 O 3 - Colophony. Rosin, common resin. Common Salt. Sodium chlorid, NaCl. Condy's Solution. Potassium permanganate, 32 gr. in 1 pint of water. Constant White. Barium tungstate. Copperas. Green vitriol, ferrous-sulphate crystals, FeS0 4 .7Aq. Copperas Blue. Cupric sulphate, CuSO 4 .5H 2 0. 504 APPENDIX. Corrosive Sublimate. Mercuric chlorid, bichlorid of mercury, HgCL. Court Plaster. Emplastrum ichthyocollae. Crab-Orchard Salts. MgS0 4 plus FeSO 4 , which obviates nauseous taste and prevents griping. Crab's Eyes or Stones. Prepared chalk. Cream of Tartar. Potassium bitartrate, KHCJ1 4 O . Small crystals float on surface of liquid on rapidly cooling a hot solution. Crocus of Antimony. Antimony vermilion or oxysulphid. Crystals of Venus. Cupric acetate, Cu(C 2 H 3 2 ) 3 .H 2 0. Cubic Niter. NaNO 3 , which crystallizes in rhombohedra closely resembling cubes. Dermatol. Bismuth subgallate; a sulphur-yellow, odorless, insol- uble powder. Dialyzed Iron. Ferric hydrate held in solution by Fe 2 Cl 6 , the ex- cess of which has been removed by dialysis. Diana. Alchemic name of silver. Dobell's Solution. A mixture of 1 1 / 2 dr. of carbolic acid, 4 dr. each of borax and baking-soda, 14 Y 2 dr. of glycerin, and enough water to make 8 oz. Donovan's Solution. An aqueous solution containing 1 per cent, each of AsI 3 and HgI 2 . Dover's Powder. Compound ipecac powder: 1 part each of ipecac and opium to 8 parts of sugar of milk. Dutch Liquid. Ethene dichlorid, C 2 H 4 C1 2 . Dutch White. Impure white lead, or a mixture of 3 parts BaS0 4 to 1 part of white lead. Earth-wax. Ozokerite, hard paraffin, fossil wax. Eau de Javelle. Solution of potassium hypochlorite, KC1O. Elixir of Vitriol. Aromatic sulphuric acid. Emerald Green. Schweinfurth green, acetoarsenite of copper, SCuAsA + Cu(C 2 H 3 O 2 ) 2 . Emery. Pulverized corundum. Epsom Salts. Magnesium sulphate, MgS0 4 .7H 2 0. Essence of Mirbane. Nitrobenzol. Ethiops Mineral. Black mercurous sulphid, Hg 2 S. Felwort. Gentian. Ferrier's Snuff. Compound bismuth powder. Fire-damp. Methane, marsh-gas, CH 4 . Flake White. Pure carbonate of lead. Flowers of Antimony. Antimonous oxid, Sb^. Flowers of Arsenic. Arsenous oxid, As 2 0.,. Flowers of Benzoin. Benzoic acid, HC 7 H 5 O;,. Flowers of Bismuth. Bismuth oxid, Bi 2 s . Flowers of Sulphur. Sublimed sulphur. Flowers of Zinc. Zinc oxid, ZnO. Fly Stone. Cobalt glance, a mixture of Co and As. Fool's Gold. Iron pyrites, FeS 2 . Fowler's Solution. A 1-per-cent. aqueous solution of potassium arsenite, K 3 AsO 3 , rendered alkaline with K 2 C0 3 . Freezine. Formaldehyd used as a preservative by milkmen. French Chalk. Talc, soapstone, steatite, magnesium silicate chiefly. Fusel Oil. Amyl alcohol, C B H n OH. GLOSSARY. 505 Glass of Antimony. Fused antimony trisulphid, Sb 2 S 3 . Glass of Borax. Borax-bead obtained by fusion. Glauber's Salts. Sodium sulphate, Na 2 SO 4 .10H 2 O. Golden Sulphur. Antimony pentasulphid, Sb 2 S 5 . Goulard's Extract and Cerate. Contain subacetate of lead, Pb- Green Precipitate. Subacetate of copper, true verdigris. Green Vitriol. Copperas, tutia, FeSO 4 .7H 2 0. Guignet's Green. Chromic hydrate obtained by heating a mixture of K 2 Cr a O 7 and boric acid, and extracting with water. Hamburg White. Mixture of 1 part of white lead and 2 parts of BaSO 4 . Hard Salt. Powdered alum. Hartshorn. Ammonia, NH 3 . Heavy Carbureted Hydrogen. Ethene or olefiant gas, C 2 H 4 . Heavy Earth. Baryta, BaO. Heberden's Ink. Mistura ferri aromatica. Hiera Picra. Aloes-and-canella powder, "hickery pickery." Hive-syrup. Compound syrup of squill. Hoffmann's Anodyne. Compound spirit of ether: 1 pint each of ether and alcohol, 6 fluidrams of ethereal oil. Holy-wood. Guaiacum, lignum vitse, pock-wood. Honey-dew. A viscid mixture of cane-sugar, dextrin, and invert- sugar, exuded from aphides on leaves. Huxham's Tincture. Compound tincture of cinchona. Ice-vinegar. Glacial acetic acid. Ignis Fatuus. Will-o'-the-wisp; spontaneous combustion of phos- phine, H 3 P, generated in marshy places. Indian Salt. White sugar. Iron Pyrites. Native sulphid of iron, "fool's gold,'* FeS 2 . Italian Juice. Licorice. Ivory Black. Animal charcoal or bone-black. James's Powder. Antimonial powder: 1 / 3 oxid of antimony, 2 / 3 calcium phosphate. Japan Black. A varnish of asphalt, umber, turpentine, and lin- seed-oil. Jesuit's Powder. Powdered cinchona-bark. Jewelers' Gold. Alloys of gold and silver. Kalk. Lime, CaO. Kelp. Sea-weed ashes used as a source of I and Na 2 CO 3 . Kermes Mineral. Oxysulphid of antimony. King's Yellow. Orpiment, As 2 S 3 . Labarraque's Solution. Solution of sodium hypochlorite, NaClO. Lady Webster Pill. Aloes pill. Lana Philosophica. Zinc oxid, ZnO. Lapis Infernalis. Lunar caustic. Lapis Lazuli. Natural ultramarine, a beautiful dark-blue pigment. Laughing-gas. Nitrous oxid, N 2 0. Lead-water. Diluted Goulard's extract, containing lead subacetate. Lemon-chrome. Chrome-yellow, PbCrO 4 . Lightning Powder. Lycopodium, "vegetable sulphur." 506 APPENDIX. Lime. Calcium oxid, CaO. Lime-water. Aqueous solution of Ca(HO) 2 about 0.15 per cent. Liquid Smoke. Pyroligneous acid. Litharge. Massicot, lead oxid, PbO. Liver of Sulphur. Hepar sulphuris; sulphureted potassium, K 2 S, a liver-brown solid. Lodestone. Native magnetic oxid of iron, Fe 3 4 . Lokas, or Chinese Green. A pigment obtained by evaporating to dryness a mixture of lime and the juice of buckthorn-berries. London Paste. Equal parts of quicklime and caustic soda, made into a paste with water; a depilatory. London Purple. Arsenical residues from anilin-dye manufactories. Lugol's Solution. lodin (5) held in solution by KI (10) in dis- tilled water (85). Luna. Alchemic name for silver/ Lunar Caustic. Stick silver nitrate, AgN0 3 , toughened with 5-per- cent. IiN0 3 . Magendie's Solution. Morphin sulphate, 16 gr. to the ounce of water. Magican. Galls. Magnesia Alba. Magnesium carbonate. Matte. Impure metal (especially Cu) containing S. Called also "regulus, or white metal." Microcosmic Salt. Sodium ammonium phosphate, NaNH 4 HP0 4 . Milk of Asafetida. The white, aqueous emulsion of this gum. Milk of Lime. Whitewash. Milk of Magnesia. Mg(HO) 2 suspended in water, 1 part to 15. Milk of Sulphur. Lac sulphuris, or precipitated sulphur, mixed with water. Mineral Blue. Prussian blue, Fe 4 (FeCy 6 ) 3 . Mineral Pitch. Asphalt. Mineral Yellow. Lead oxychlorid. Monsel's Solution. Liquor ferri subsulphatis, Fe 4 0(S0 4 ) 5 . Mosaic Gold. Brass or stannic sulphid, a golden-yellow powder used for bronzing. Mountain-blue. Azurite, native basic cupric carbonate. Mountain-green. Malachite, native basic cupric carbonate. Muriatic Acid. Hydrochloric acid, HC1. Music Metal. Alloy of Sn and Sb. Mystery Gold. Alloy of 1 part Pt and 2 parts Cu with a little silver. It resists action of strong nitric acid. Naples Yellow. A basic lead antimonate used in oil-painting. Natron. Native sodium carbonate, Na 2 CO 3 . Neutral Mixture. Solution of potassium citrate, K 3 C H 5 7 . Niter. Saltpeter, KN0 3 . Obsidian. Volcanic glass; trachyte or rhyolite. Ocher. Native mixture of clay and ferric oxid, used as a paint. Oil of Vitriol. Sulphuric acid, H 2 S0 4 . Oil of Wine. Ethyl sulphate, (C 2 H 5 ) 2 S0 4 . ' Olefiant Gas. Ethene, C 2 H 4 ; so called because it makes an oily liquid with Cl. Oleum Calcis. The thick, oily liquid resulting from deliquescence of CaCl 2 exposed to the air. GLOSSARY. 507 Oxidized Silver. Coating of thin layer of sulphid, obtained by heating together Ag and solution of K 2 S. Ozonized Ether. Solution of H^O 2 in ether. Ozonized Water. Aqueous solution of H 2 O 2 . Packfong. German silver, or brass whitened by nickel. Palsy Drops. Compound tincture of lavender. Paris Black. Finely ground animal charcoal. Paris Green. Impure Schweinfurth, or mitis, green, Cu(C 2 H 3 2 ) 2> - 3CuAs 2 O 4 . Paris Yellow. Lead chromate, PbCr0 4 . Pearl Ointment. Zinc-oxid ointment. Pearl Powder or White. Subnitrate or subchlorid of Bi, or ZnO. Pearl-ash. Crude potassium carbonate, K 2 CO 3 , calcined in a furnace till white. Pearson's Salt. Sodium arsenate, Na 3 As0 4 . Pectoral Powder. Pulvis glycyrrhizae compositus. Permanent White. Barium sulphate or carbonate not darkened by H 2 S. Phlogiston. Hydrogen. Phosgene-gas. Carbonyl chlorid, COC1 2 . Pink Salt. Stannic chlorid with ammonium chlorid. Pink Saucers. Carthamin, a red dye in safflower. Plaster of Paris. Calcined gypsum or calcium sulphate. Plate Pewter. An alloy of Sb and Sn used for faucets and domestic utensils. Platinum Black and Sponge. Finely divided Pt. Plumbago. Black lead, graphite, a form of native carbon. Plummer's Pill. Compound antimony pill, Sb 2 S 3 , Sb 2 3 , and calomel. Poison-nut. Nux vomica. Pompholix. Zinc oxid, ZnO. Potash. Impure potassium carbonate, K 2 CO 3 . Potassa. Potassium oxid or hydrate. Potato-oil. Crude amyl alcohol. Pot-metal. An alloy of Cu and Pb. Pounce. Powdered gum juniper. Preservaline or Rex Magnus. A mixture of borax and boric acid. Prince's Powder. Red oxid of mercury, HgO. Printers' Ink. Thoroughly boiled linseed-oil varnish, containing lamp-black or other color and a little soap. Proof-spirit. The old name applied to dilute alcohol 49 1 / 4 per cent., by weight (57 per cent., by volume) ; so called because this is the lowest alcoholic limit with which gunpowder will take fire. Prussian Blue. Ferric ferrocyanid, Fe 4 (FeCy 6 ) 3 . Prussic Acid. Hydrocyanic acid, HCN. Puce Oxid of Lead. Brown or peroxid of lead, Pb0 2 . Punk. Amidou, touch-wood; made by steeping a fungus in salt- peter solution, and then drying thoroughly. Purple of Cassius. Pigment made by mixing solutions of AuCl 3 and SnCL; probably Au 2 OSn 3 O 3 . Putty. Mixture of whiting and linseed-oil. Putty Powder. Stannic oxid, Sn0 2 . Queen's Metal. An alloy of Sb, Sn, etc., used in jewelry. Quevenne's Iron. Iron reduced by hydrogen. Quicklime. Caustic lime, CaO. Quicksilver. Metallic mercury. 508 APPENDIX. Ratsbane. Nux vomica, phosphorus, arsenic. Red Blister. Uuguentum hydrargyri iodidi rubri. Red Cerate. Calamine ointment. Red Fire. Sr(NO 3 ) 2 , 50 parts; KC1O 3 , 25 parts; powdered shellac or sugar, 25 parts; mixed without friction through a sieve. Red Lead. Minium, plumboso-plumbic oxid, (PbO) 2 Pb0 2 . Red Oil. Oleic acid as a by-product in the manufacture of stearic acid candles. Red Precipitate. Red mercuric oxid, HgO. Red Pmssiate of Potash. Potassium ferricyanid, K Fe 2 Cy 12 . Red Tartar. Argols, impure cream of tartar. Regulus of Antimony. Metallic antimony. Regulus of Arsenic. Metallic As obtained by reduction of As 2 3 with powdered C. Rex Metallorum. Gold. Rinman's Green. A pigment made by pptg. a mixture of zinc and cobalt sulphates with Na 2 CO 3 , and igniting ppt. after washing. Rochelle Salt. Potassium and sodium tartrate, KNaC 4 H 4 O . Rose Pink. Whiting colored w r ith a decoction of Brazil wood and alum. Rouge. Mineral: finely powdered ferric oxid. Animal: carmin and chalk. Vegetable: carthamin and chalk. Rust. Ferric oxid and hydrate. Safety Oil. Petroleum naphtha. Sal Alemboth. Salt of wisdom; double chlorid of mercury and ammonium, NH 2 HgCL Sal Ammoniac. Ammonium chlorid, NH 4 C1. Sal Diureticus. Potassium acetate, KC 2 H 3 2 . Sal Enixum. Potassium bisulphate, KHSO 4 . Sal Marinum or Fossile. Sodium chlorid. Sal Mirabile. Sodium sulphate, Na 2 SO 4 . Sal Perlatum. Sodium phosphate. Sal Polychrest. Sal de duobus, potassium sulphate, K 2 SO 4 . Sal Prunelle. Fused saltpeter, KNO 3 . Sal Soda. Impure Na 2 CO 3 , containing hydrate. Sal Vegetabile. Potassium tartrate. Sal Volatile. Ammonium carbonate or aromatic spirit of ammonia. Saleratus. Potassium bicarbonate, KHC0 3 . Salt of Lemon or Sorrel. Potassium binoxalate, KHC 2 O 4 . Sa.lt of Mars or Steel. Sulphate of iron. Salt of Saturn. Lead acetate, Pb(C 2 H 3 2 ) 2 . Salt of Tartar. Pure potassium carbonate, K 2 C0 3 ; so called be- cause sometimes made by burning cream of tartar and lixiviating residue. Saltpeter. Potassium nitrate, KNO 3 . Saprol. A dark-brown, oily cresol much used in Germany as a dis- infectant. Scheele's, or Swedish, Green. Cupric arsenite, CuHAsO 3 . Schlippe's Salt. Sodium sulphantimonate, Na s SbS 4 , used in pho- tography. Schweinfurth, or Vienna, Green. Same as Paris green. Sedative Salt. Boric acid, H 3 BO 3 . Seidlitz Powder. Compound effervescing powder: Tartaric acid (35 gr.) in white paper; Rochelle salt (120 gr.) and sodium bicarbonate (40 gr.) in blue paper. Seignette Salt. Same as Rochelle salt. GLOSSARY. 509 Sienna. Native oxid of iron used as a red pigment. Smalt. Powdered glass colored blue with oxid of cobalt. Smelling Salts. Sal volatile, chiefly ammonium carbonate. Soda Saltpeter. Sodium nitrate, NaNO 3 . Soda-water. Water charged artificially with C0 2 under pressure. Soldiers', or Troopers', Ointment. Unguentum hydrargyri mitis. Soluble, or Water, Glass. Sodium silicate, Na 2 Si 4 O B . Soluble Starch. Amylodextrin. Sory, or Shoe-makers', Black. Sulphate of iron. Speculum Metal. An alloy of Cu and Sn. Speiss. Impure fused nickel arsenid. Spelter. Commercial zinc or an alloy of equal parts Zn and Cu. Spiegeieisen. Ferromanganese. Spirit of Hartshorn. Solution of NH 3 in alcohol. Ammonia was formerly made from horns and hides. Spirit of Mindererns. Solution of ammonium acetate, made by neutralizing dilute acetic acid with ammonium carbonate. Spirit of Niter. Nitric acid, HNO 3 . Spirit of Salt. Hydrochloric or marine acid, HC1. Spirit of Vinegar. Dilute acetic acid, HC 2 H 3 O 2 . Spirit of Wine. Rectified ethyl alcohol, C 2 H 5 OH, of 84-per-cent. strength. Steel Drops. Tincture of chlorid of iron. Steinbuhl Yellow. Barium chromate, BaCr0 4 . Strike. Liquor ammonise. Stucco. Calcium sulphate, CaSO 4 . Sugar of Lead. Lead acetate, Pb(C 2 H 3 2 ) 2 . Sulphuric Ether. Ethylic ether, (Q,H 5 ) 2 O. Sweet Precipitate. Mercuric chlorid, HgCl 2 . Sweet Principle of Fats. Glycerin was formerly so called. Sweet Spirit of Niter. Spiritus setheris nitrosi, C 2 H 5 N0 2 . Talmi Gold. Alloy of Cu and Al. Tar Balls. Coal-tar camphor, naphthalene. Tar Spirit. Benzol, C 6 H G . Tartar Emetic. Potassium antimonyl tartrate, KSbOC 4 H 4 O 6 . Terra Alba. Argilla, kaolin or bolus alba, a white argillaceous earth. Thenard's Blue. A compound of the oxids of Al and Co. Thenard's Green. Phosphate of cobalt. Tin Salt. Tin- ash or crystals: stannous chlorid, SnCl 2 .2H 2 O. Tincal. Native borax, Na 2 B 4 O 7 .10H 2 0. Tombac. Copper alloyed with As and used for imitation jewelry. Tournesol. Litmus, laque blue. Tripoli. Diatomaceous earth, chiefly fine silica, used as a polishing powder. Trona. Native sodium carbonate, Na 2 C0 3 . Tully's Powder. Compound morphin powder: 1 part of morphin to 20 each of camphor, licorice, and calcium carbonate. TurnbulFs Blue. Ferrous ferricyanid, Fe 8 (Fe 2 Cy, 2 ). Turner's Cerate. Calamine ointment. Turner's Yellow. Lead oxychlorid. Turpeth Mineral. Queen's yellow, subsulphate of mercury, HgS0 4 .- 2HgO. Tutenag. Zinc. Tutty. Impure zinc oxid, ZnO. 510 APPENDIX. Ultramarine, or Washing, Blue. Lapis lazuli, a blue pigment com- posed of sodium sulphid and aluminum sodium silicate. Umber. Sienna or chestnut brown, native aluminum silicate with oxids of iron and manganese, used as brown paint; darkened in tint by burning. Valangin's Solution. Solution of As 2 3 with dilute HC1. Vallet's Mass. Ferrous carbonate in pill mass. Varec. Kelp, or ash of sea-weeds. Venetian Red. An ocher, the color of which is due to ferric oxid. Venus. Alchemic name for copper. Verditer Green. Basic copper carbonate. Vermilion. Artificial mercuric sulphid, HgS. Vinegar of Lead. Liquor plumbi subacetatis, a solution of PbO in Pb(C 2 H 3 O 2 ) 2 solution. White Acid. A mixture of HF and NH 4 F used for etching glass. White Arsenic. Arsenous oxid, As 2 O 3 . White Lead. Basic lead carbonate, (PbC0 3 ) 2 Pb(HO),. White Metals. Alloys of Ni with Cu and Zn: albata, British plate, electrum, packfong, tutenag, white copper, etc. White Precipitate. Ammoniated mercury, NH 2 HgCl. White Vitriol. Zinc sulphate, ZnS0 4 . Whiting. Prepared chalk, CaC0 3 , or white clay. Wood-spirit, or Naphtha. Methyl alcohol, CH 3 OH. Wood-vinegar. Pyroligneous, or impure acetic, acid. Yellow Ointment. tTnguentum hydrargyri nitratis. Yellow Prussiate of Potash. Potassium ferrocyanid, I^FeCy,.,. Yellow W^ash. Mercuric oxid, HgO, made by adding HgCl 2 to lime- water. Zaffre. Impure cobaltous oxid from roasting sand and ore. Zinc, or Chinese, White. Zinc oxid, used as paint. INDEX. Absinthin, 230 Absorption, 398 of gases, 18 Acetals, 212 Acetamid, 238 Acetanilid, 239, 326, 356 Acetates, 177 Acetic acid, 213, 368, 419 Aceton, 212, 369, 376, 454 Acetonuria, 454 Acetylene, 196, 326 Acid, finding, 263 Acidity, 82 Acids, 80, 81, 144 Aconite poisoning, 355 Aconitin, 244 Actinism, 37, 102 Action of air, light, and atmos- pheric heat, 303 of air on metais, 100 of metals on water, 100 Acute poisoning, 336 Adenin, 370 Adhesion, 5 Adipocere, 215, 371 Adonidin, 230 Adrenalin, 390 Adulterants and sophisticants, 319 Agglutination, 415 Air, 125, 307 Albuminates, 247, 250 Albuminoid ammonia, 317 Albuminoids, 249 Albuminometer, 449 Albumins, 246, 247 Albuminuria, 441 Albumoses, 247, 408 Albumosuria, 449 Alcohol, 326, 410, 419 poisoning, 352, 360 Alcohols, 204 Aldehyds, 210 Alizarin, 233 Alkaline phosphates, 434, 465 Alkaloids, 241, 245, 277, 278, 290, 291 Alkaptonuria, 455 Alkyl salts, 203 Allantoin, 444 Allotropic elements, 59, 73, 99 Alloxan, 369 Alloxuric bodies, 369, 441 Alloys, 107 Allyl sulphid, 237 Aloins, 234 Alum poisoning, 347 Aluminates, 173 Amalgam alloys, analysis, 286 Amalgamation, 48 Amido-acids, 239, 369 Amido-phenols, 237 Amids, 238 Amins, 238 Ammonia, 152, 315, 444 Ammoniacal fermentation of urine, 430 Ammonium, 95 compounds, 102 microchemic test, 281 Ampere, 49 Amygdalin, 230 Amyl nitrite, 210 Amyloid corpuscles, 474 substance, 248 Amylopsin, 252, 381 Anabolism, 400 Anhydrids, 138 Anilids, 239 Anilin, 239 Animal electricity, 52 foods, 407 functions, 396 heat, 400 irritants, 349 Anions, 61, 83 Annatto, test, 321 Anode, 46 Anthracene, 199 Anticytotoxins, 415 Antidotes, 342 Antimonates, 172 Antimony poisoning, 346, 359 Antipyrin, 240 Antiseptics, 326 (511) 512 INDEX. Antitoxins, 245, 413 Anuria, 431 Apomorphin, 243 Aqua, 29 Aqueous vapor, 308 Arbutin, 231 Aristol, 204 Aromatic series, 198 Arrow-poison, 356 Arsenates, 171 Arsenic and arsenous acids, 151 poisoning, 345, 358 tests, 279, 281 Arsenites, 171 Artesian wells, 12 Articular diseases, 481 Asbestos, 176 Ascitic fluid, 395 Ash of milk, 422 Aspidospermin, 245 Assays, pharmaceutic, 283 Atmosphere, 17 Atomic heat, 25 weights, 73 Atomicity, 73 Atoms, 4, 72 Atropin, 243, 282 Attraction, 4 Audiphone, 65 Autointoxication, 411 Autotoxemia, 411 Avogadro's law, 16 Azo compounds, 240 Bacteria in milk, 320 Bacteriolysins, 415 Bacteriuria, 475 Balloons, 18 Balsams, 198 Baptism, 231 Barium poisoning, 347 test, 282 Barometer, 17 Bases, 81 Basic oxids, 133 Basicity, 81 Battery, 46 -fluids, 47 Beer, 206, 324 Bee-stings, 364 Benzene, 198 Benzin, 193 Benzoates, 180 Benzoic acid, 217, 326 Berberin, 244 Beverages, 410 Bicarbonates, 165 Bile, 381, 384 -pigments, 384, 455 -salts, 444 Bilicyanin, 371 Biliousness, 411 Bilirubin, 371, 384 Biliverdin, 371, 384 Bilixanthin, 371 Bitter principles, 234 Bixin, 233 Bleaching powder poisoning, 347 Blood, 375 in urine, 457 Blow-pipe, 270 Body-fat, 368 Boiling-point, 22, 24 Bones, 371 Borates, 170 Borax bead tests, 273 in milk, 320 Boric acid, 149, 320, 327 Boroglycerin, 207 Boron, 128 Bottger's test for sugar, 452 Botulismus, 349 Brain, 374 Brasilin, 233 Bread, 321, 408, 409 Bright's disease, differentiation, 477 Bromates, 158 Bromelin, 252 Bromids, 157 Bromin, 118, 327 Bromism, 362 Bromoform, 204 Brucin, 244, 3.56 Bryonin, 231 Bunsen flame, 270 Butter, 221, 320, 387 Butyric acid, 215, 369, 419 Cachexias, 412 Cacodyl, 238 Caffein, 370 Cake, 321 Calabar bean, 356 Calcium carbonate crystals, 464 oxalate, 444, 463 phosphate crystals, 463 sulphate crystals, 464 test, 282 Calculi of urinary tract, 483 Calorie, 31, 405 Calorimeter, 31, 401 Camera lucida, 35 obscura, 36 INDEX. 513 Camphor, 197, 353 Cane-sugar, 227 Caimabis Indica poisoning, 352 Canned goods, 321 Cantharidin, 234 Cantharis. 349 Caoutchouc, 197 Capillary attraction, 10 Carbainic acid, 239 C'arbamid, 238 Carbazotic acid, 236 Carbids, 1G8 Carbohydrates, 224 Carbolates, 181 Carbolic acid, 235, 327, 345 Carbon, 129 compounds, 189 dioxid poisoning, 353 monoxid hemoglobin, 379 poisoning, 353 salts, 165 Carbonates, 165, 367 in urine, 436 Carbonation, 305 Carbonic acid, 149 Carbylamins, 241 Cardiac failure, 19 Carminic acid, 232 Cartilage, 375 Caseinogen, 248 Caseins, 247, 387 Casts, 465 Catabolism, 400 Cataphoresis, 51 Cathartic acid, 231 Cathode, 46 Cations, 61, 83 Caustic alkalies, 344 Celluloid, 226 Cellulose, 225 Cement of teetn, 372 Cements, 175 Centrifuge, 425, 459 Cephalin, 245 Cerebrin, 231, 368 Cerebro-spinal fluid, 390 Cerumen, 386 Charcoal, 130 Charles's law, 16 Cheese, 321, 407 Chemism, 5 Chemistry, 1 Chicory, 323 - Chinolin, 240 Chitins, 231, 249 Chloral, 211, 328, 352, 369 Chloralamid, 238 Chlorates, 156 Chlorids, 154, 314, 344, 367 Chlorin, 116, 328 Chloroform, 203, 328, 357 Chlorophyl, 232 Chocolate, 323 Cholalic acid, 371 Cholemia, 377 Cholesterin, 371, 464 Cholin, 370 Choluria, 427, 455 Chondrigen, 375 Chondrin, 249 Chromates, 172 Chromatic aberration, 38 Chromium poisoning, 363 Chromoproteids, 248 Chronic poisoning, 357 Chyle, 389 Cnyluria, 428, 429, 456, 474 Chymosin, 253 Cimicifuga, 234 Cinchona group, 243 Cinchonidin, 243 Cinchonin, 243 Cinnamic acid, 217 Citrates, 178 Citric acid, 217, 328 Clays, 175 Cleavage, 60 Clotting of blood, 377 Coal, 129 -gas, 194 poisoning, 353 -tar antipyretics, 356 dye-colors, 233 Cobalt salts, 102 Cocain, 244, 355, 361 Cocculus Indicus, 357 Cochineal, 232 Cocoa, 323, 411 Codein, 243 Coffee, 323, 362, 410 Cohesion, 5 Coke, 130 Colchicum poisoning, 348 Collagen, 249, 371, 374, 375, 408 Collodion, 226 Colloids, 11 Colocynthin, 231 Color, 36, 37 -changes, 304 of metals, 97 of urine, 426 of water, 314 Coloring matters of urine, 445 vegetable, 232 514 INDEX. Colostrum, 388 Combination of metals, 90 Combustion, 299 Compound ammonias, 238 solvents in aqueous solutions, 297 Compressibility, 6 Condensers, 43 Condiments, 324, 409 Conduction, 20, 44 Confectionery, 323 Coniferin, 231 Coniin, 242 Conium poisoning, 355 Conjugate sulphates, 436 Connective tissue, 374 in urine, 474 Consistence of urine, 429 Constitutional diseases, 481 Contamination of water, 318 Convallamarin, 231 Convection, 20 Convolvulin, 231 Convulsants, 356 Cooking, 409 Copper poisoning, 347, 359 sulphate, 329 test, 281 volumetric estimation, 279 Corrosion of metals, 103 Corrosive sublimate, 282, 344 Corrosives, 343 Cotoin, 231, 234 Coulomb, 50 Cream, 422 Creasote, 235, 329 Creatin, 369, 409, 443 Creolin, 329 Cresol, 235 Crystallin, 247 Crystallization, 10 Crystallography, 58 Crystalloids, 11 Crystals in urine, 460, 461 Cubebin, 234 Cupric and cuprous salts, 102 Curare, 356 Curcumin, 232 Cyanates, 182 Cyanid of zinc and mercury, 329 Cyanids, 182, 241, 354 Cyanogen poisoning, 363 Cyano-salts, 182 Cyanosis, 404 Cylindroids, 466 Cystic contents, 394 Cystin, 456 Cystinuria, 456 Daturin, 243 Decoctions, 29 Deliquescent compounds, 303 Density, 18, 73 Dental amalgam alloys, 110 caries, 373 dies, 112 enamel, 174 porcelain, 174 rubber, 197 solders, 111 Deodorants, 326 Depressants, 354 Derivation of metals, 89 Dew-point, 26 Dextrin, 226 Dextrose, 229, 368, 376 Diabetes mellitus, 452 Diacetic acid, 368, 454 Diaceturia, 454 Diagnosis of non-urinary diseases, 478 Dialysis, 11, 62 Diamm, 240 Diamond, 129 Diastase, 251 Diazo compounds, 240 reaction, 478 Diet, 405 Diffraction, 37 Diffusion, 16 Digestion, 396 Digestive fluids, 380 Digitalin, 231 Digitalis poisoning, 349 Dionin, 244 Direct combination of metals, 100 Disinfectants, 326 Distillation, 26 Divisibility, 3 Dog-bite, 364 Double refraction, 40 Drinking-water, 311 Dropsy, 403 Drug impurities, 325 Drugs and urine, 427, 428 Drying oils, 220 Ductility, 9 Dynamic electricity, 43 Dynamo, 55 Dyne, 50 Dyspnea, 404 Ear, 64 Earthy phosphates, 434, 465 INDEX. 515 Ebullition, 27 Edestin, 247 Effects of heat, 30 Effervescence, 299 Efflorescent compounds, 303 Eggs, 408 Ehrlich's test for typhoid, 478 Elaidin test, 222 Elasticity, 6, 9 Elastins, 249, 371, 374, 408 Elateriri, 234 Electric current, 48 eel, 52 heat, 56 light, 56 Electricity, 42 Electrocauterization, 51 Electrocution, 51 Electrolysis, 50, 91 Electrolytes, 61, 62, 83 Electromagnetism, 54 Electromotive force, 48 Electroplating, 50 Electrotonus, 50 Electrotyping, 50 Eleidin, 249 Elementary analysis, 284 Elements, 70 Emetin, 244 Emulsin, 251 Emulsions, 29 Enamel, 372 Energy, 7, 401 Enteroliths, 392 Enzymes, 249, 251, 444 Epilation, 51 Epinephrin, 390 Epithelia, 374, 472 Equations, 85 Eremacausis, 191 Erepsin, 252, 381 Ergot, 349, 361 Erythrocytes, 376 Esbach's method, 449 Esculin, 231 Eserin, 244 Essences, 29 Essential oils, 196, 348 Ether, 32 Ethereal sulphates, 436 Ethers, 208, 210, 329, 353 Ethyl chlorid, 203 nitrite, estimation, 283 Eucalyptol, 329 Euonymin, 234 Europhen, 204 Evaporation, 25, 305 Exalgin, 239 Excretions, 391 Expansion, 16, 21 Explosion, 299 Extension, 2 Extraction of metals, 91 Exudates, 295 Farad, 50 Faradic battery, 55 Fat in urine, 456, 474 Fats, 219, 408 Fatty acid crystals, 464 series, 192 Feces, 391 Fermentation test, 452 Ferments, 251 Ferric and ferrous compounds, 101 Ferricyanids, 183 Ferrocyanids, 183 Ferrous sulphate, 329 Fibrin-ferment, 253 Fibrinogen, 247 Fibrins, 247, 378 Fibrinuria, 429, 451 Fibroin, 249 Filariasis, 456 Filters, 312, 313 Fish, 407 poisons, 350 Fixed oils, 219, 288 Flame tests, 273 Fleitmann's test, 280 Flexibility, 10 Flour, 321 Fluorescence, 37 Fluorids, 159 Fluorin, 115 Fluoroscopc, 55 Food, 404 Foot-pound, 7 Force, 7 Formaldehyd, 210, 329, 353 Formalin in milk, 319 Formamid, 238 Formates, 180, 368 Formic acid, 213, 368 Formulas, 77 Fractional crystallization, 60 distillation, 27, 92 Fraxin, 231 Freezing mixtures, 31 -point, 22, 24 Frictional electricity, 43 Fuchsin, 234 Fulminates. 241 Fusel oil, 206 516 INDEX. Fusion-point of metals, 97 Galactose, 230 Galactotoxicons, 350 Gallates, 179 Gallic acid, 218 Gallotannic acid, 217 Galvanic cell, 45, 46 electricity, 45 Game, 407 Gaseous irritants, 350 Gases, 8 of body, 367 Gas-formation, 279 Gastric absorption, 421 juice, 381, 382, 418, 420 motility, 421 Gastro-intestinal diseases, 480 Gelatin, 249, 408 Gelatinoids, 249 General rules of incompatibility, 294 Gentiopicrin, 231 Glass, 174 Gliadin, 249 Globin, 247 Globulins, 247 Globulinuria, 446 Glucosids, 230 Glue, 249 Glycerin, 207, 330 Glycerophosphoric acid, 208, 446 Glycocholic acid, 370 Glycocoll, 239, 370 Glycogen, 227, 368, 376 Glycols, 207 Glycoproteids, 248 Glycosuria, 451 Glycuronic acid, 455 Glycyrrhizin, 231 Gmelin's test for bile-pigment, 456 Gold, 94 refining, 287, 292 Gonococcus, 476 Granular effervescing salts, 217 Granulated metals, 95 Granules in urine, 464 Graphite, 129 Gravimetric methods, 273 Gravitation, 4 Gravity, 4 Green soap, 223 Groups of metals, 107 Guanin, 370 Guaranin, 245 Gum-resins, 198 Gums, 227 Gun-cotton, 226 Gunpowder, smokeless, 226 Gutta-percha, 197 Haines's test for sugar, 452 Hair, 374 Halogens, 115 Haloid salts, 154 Hardness, 8 of metals, 97 of water, 314 Heat, 19 Helium, 115 Hellebore poisoning, 349 Helleborin, 231 Hematin, 278 Hematoidin, 379, 462 Hematoporphyrin, 379 Hematoxylin, 232 Hematuria, 457, 471 Hemic and circulatory disorders, 479 Hemin, 378 Hemlock poisoning, 355 Hemoglobins, 248, 378 Hemoglobinuria, 458 Hemolysins, 414 Hepatic lesions, 481 Heroin, 243 Heterolysins, 414 Heteroxanthin, 370 Hippuric acid, 443, 463 Histon, 247 Histozym, 253 Homatropin, 243, 282 Horse-power, 7 Human body, chemic composition, 366 Hydatid fluid, 395 Hydrant- water, 310 Hydrastin, 244 Hydraulic press, 12 Hydrazins, 240 Hydremia, 376 Hydro-acids, 144 Hydrocarbon derivatives, 200 Hydrocarbons, 191 Hydrochloric acid, 144, 382, 418 Hydrocyanic acid, 218, 281, 282, 354 Hydrogen, 113 Hydrometer, 14 Hydroquinone, 235 Hydroxids, 151 Hygrometer, 26 Hyoscin, 243, 282 Hyoscyamin, 243 INDEX. 517 Hyoscyamus poisoning, 352 Hyperinosis, 370 Hypinosis, 376 Hypobromites, 158 Hypochlorites, 157 Hypophosphites, 165 Hypostheniants, 354 Hyposulphites, 165 Hypoxanthin, 370 Ice-water, 310 Ichthyol, 236 Ichthyotoxins, 350 Ignatia, 356 Images, 34 Immunity, 412 Impenetrability, 3 Incandescence, 33 Incompatibility, 2l>4 Incubation period, 412 Indestructibility, 2 Indican, 233, 368 Indicanuria, 436, 465 Indicators, 275 Indigo in urine, 465 Indol, 369 Induction, 43 Inertia, 7 Infection, 412 Infusions, 29 inorganic acids, 144 Inosit, 368 Inosituria, 453 Intentional incompatibility, 303 Interference of sounds, 64 Internal secretions, 390 Intestinal bacteria, 398 juice, 381, 385 Intoxication, 412 Inulin, 230 Invertase, 252, 381 Invertin, 252 lodates, 159 lodids, 158 lodin, 118, 347 lodism, 362 lodoform, 204, 330 lodol, 240 Ions, 61 Iridescence, 37 Iron, 93 poisoning, 347 Irritants, 345 Isoamylamin, 238 Isocyanids, 241 Isosulphocyanates, 241 Jalapin, 231 Jecorin, 368 Kairin, 240 Kaleidoscope, 34 Keratins, 249, 408 Kerosene, 194 Ketones, 212 Kiestein, 463 Kjeldahl's method, 439 Lab-ferment, 253 Labile compounds, 72 Laburnum, 349 Lactates, 179 Lactic acid, 216, 330, 369, 419, 421, 457 Lactoscope, 423 Lactose, 229, 368, 387, 424. Lactosuria, 453 Lamp-black, 148 Lanolin, 222 Lard, 320 Lardacein, 248 Larynx, 65 Latent heat, 30 Lathyrus, 349 Laughing-gas, 139 Lead plaster, 224 poisoning, 346, 3o7 test, 282 Lecith-albumins, 248 Lecithins, 222, 368 Legal's test for aceton, 454 Legumin, 247 Lemon- juice, 411 Lenses, 35 Leptandrin, 231 Leucin, 239, 369, 462 Leucocytosis, 376 Leucomains, 245 Levulose, 229, 230 Lieben's test for aceton, 454 Liebig's test, 281 Life, 401 Light, 32 Lightning, 45 Lignin, 226 Lime, 331 Liniments. 223 Lipaciduria, 457 Lipase, 253 Lipemia, 377 Lipuria, 456 Liquefaction, 25 on trituration, 302 Liquid air, 125 518 INDEX. Liquids, 8 Liquor, 29 Liquors, 206 Lithernia, 411 Lithium, test, 282 Litmus, 232 Lobelia poisoning, 355 Lobelin, 242 Loudness of sound, 63 Lunar caustic, 345 Lymph, 389, 403 Magnesium, test, 281, 282 Magnetic poles, 53 Magnetism, 53, 54 Maize, damaged, 362 Malates, 180 Malic acid, 216 Malleability, 9 Maltase, 381 Maltin, 251 Maltose, 229 Manganates, 172 Mariotte's law, 16 Marsh's test, 280 Mayer's solution, 277 Meat-extracts, 408 Meats, 321, 407 Mechanic equivalent of heat, 32 Meconates, 181 Meconium, 392 Melanin, 374, 375, 455, 465 Melanuria, 455 Mendelejeff's table, 86 * Mephitic poisoning, 309 Mercaptans, 236 Mercuric and mercurous salts, 112 chlorid, 331 Mercury poisoning, 359 test, 281 Metabolism, 400 Metal, finding, 259 Metalbumin, 394 Metalloids, 113 Metals, 89 Metaphosphates, 170 Methane, 193 Methyl chlorid, 203 Methylene blue, 331 Metric system, 2 Mezcalin, 245 Microchemic tests, 281, 282 Microchemistry of urine, 459 Microscope, 35 Milk, 319, 386, 407, 421 -fat, 422 poisons, 350 Milk, proteins, 424 Milliamperemeter, 49 Mineral acids, 331, 343 irritants, 345 waters, 311 Mirage, 35 Mobility, 7 Molasses, 322 Molds in urine, 476 Molecular weight, 74, 285 Molecules, 4, 77 Momentum, 7 Morphin, 243, 282, 351, 361 Mucin, 248, 445 bands, 466 Mucoids, 248 Mucus, 385 cells in urine, 471 Murexid test, 442 Muscarin, 352 Muscle, 373 Musical scale, 64 Mustard, 331 -oils, 241 Mycoderma aceti, 253 Myosin-ferment, 253 Myosinogen, 247 Myronic acid, 231 Myrosin, 252 Nails, 374 Naphtha, 194 Naphthalene, 199, 331 Naphtols, 236 Narcotics, 350 Narcotin, 243 Natural gas, 195 waters, 309 Nephritides, differentiation, 477 Nerve-substance, 374 Nervous diseases, 482 Nesslerizing, 315 Neurin, 370 Neurokeratin, 249 Neurolemma, 374 Neurotics, 350 Nicol prism, 40 Nicotin, 242, 355 Nitrates, 160, 317, 345 Nitrifying ferments, 254 Nitrils, 241 Nitrites, 161, 317 Nitro-acids, 149 Nitrobenzene, 236, 354 Nitrocelluloses, 226 Nitrogen, 124 Nitroglycerin, 209 INDEX. 519 Nitrometry, 282 Nitroprussids, 183 Nitro-salts, 159 Nomenclature, 79 Normal constituents of urine, 434 serum, 413 solutions, 275, 276, 277 Noxious trades, 309 Nucleins, 248, 370 Nucleoproteids, 248 Nuts, 409 >,ux vomica, 356 Odor of urine, 428 Ohm, 49 O'idhtm albieans, 253 Oleates, 179 Olefins, 195 Oleic acid, 215 Oleomargarin, 221, 320 Oleoresins, 198 Oliguria, 431 Oliver's test for bile-salts, 445 Opera-glass, 35 Ophthalmoscope, 36 Opium group, 243 poisoning, 351, 361 Oppler-Boas bacilli, 420 Orellin, 233 Organic acids, 213, 368 acid salts, 176 matter in water, 315 Osmazome, 407 Osmosis, ll s 61, 403 Ossein, 249, 371 Osseous diseases, 481 Oxalates, 176 Oxalic acid, 216, 282, 344, 369 Oxaluria, 444 Oxidation, 77, 305 Oxidimetry, 278 Oxids, 131 Oxybutyria, 454 Oxybutyric acid, 368, 454 Oxydases, 252 Oxygen, 119, 331 Oxyhemoglobin, 378 Ozone, 121, 332 Pancreatic juice, 381, 385 lesions, 481 Papain, 251 I'apaverin, 243 Paracasein, 247 Paraffin, 194 Paraffins, 192 Paralbumin, 246 Paraldehyd, 211 Parasites in urine, 474 Paraxanthin, 370 Pectin, 227 Pellotin, 245 Pepsin, 252, 381, 419 Peptonized foods, 408 Peptons, 248 Peptonuria, 449 Perchlorates, 157 Periodic law, 87 Peronin, 244 Peroxid of hydrogen, 332 Petroleum, 193, 332 Pharmaceutic assays, 283 Phenacetin, 237 Phenazone, 240 Phenol-phthalein, 236 Phenols, 235, 345, 369 Phenyl-anilin, 230 Phenyl-hydrazin, 240 Phenylic acid, 235 Phloridzin, 231 Phonograph, 65 Phosphates, 168, 315, 367, 406 Phosphaturia, 428, 430, 434, 435, 465 Phosphids, 170 Phosphin, 127 Phosphites, 170 Phosphorescence, 33 Phosphoric acid, 150 Phosphoms, 126, 348, 360 test, 281 Phospho-salts, 1(58 Photography, 38 Photogravure, 50 Phototherapy, 38 Phthalein group, 234 Physic properties of metals, 95 Physics, 1 Physiologic and pathologic chem- istry, 366 properties of metals, 103 Physostigma poisoning, 356 Physostigmin, 244 Phytolaccin, 234 Pialyn, 253, 381 Picnometer, 14 Picric acid, 236, 324 Picrotoxin, 234, 357 Pilocarpin, 244 Piperazin, 238 Piperin, 244 Pitch, 64 Platinum, 95 520 INDEX. Plumage pigments, 380 Poisonous bites and stings, 363 metals, in water, 318 reactions, 300 Poisons and urine, 483 Polarimeter, 41 Polariscope, 41 Polariscopy, 42 Polarity, 74 Polarization, 40 Polyuria, 431 Populin, 232 Porcelain, 174 Porosity, 5 Post-mortem examinations, 339 Potable water, 309 Potassium permanganate, 332 salts poisoning, 347 test, 282 Practical physic and chemic in- compatibility as applied to medicine, 298 Precipitate, 84 Predigested foods, 408 Prescriptions, 303 Pressure of atmosphere. 17, 18 of liquids, 11 on immersed bodies, 12 Prism, 35 Propeptons, 247 Propionic acid, 215, 369 Protagon, 68 Proteids, 248 Proteins, 246 of urine, 450 Proteoses, 247 Prothrombin, 377 Protoplasm, 371, 401 Pmssic acid, 354 Pseudocasts, 470 Pseudopepsin, 381 Ptomains, 245, 459 Ptyalin, 252, 381 Purdy's test for sugar, 453 Purification of water, 312 Purin, 370 bodies, 369, 441 Putrefying ferments, 254 Putrescin, 238 Pyridins, 240 Pyrocatechin, 235 Pyrogallin, 235 Pyrology, 269 Pyrophosphates, 169 Pyroxylin, 226 Pyrrol, 240 Pyuria, 458, 470 Qualitative analysis, 256 Quality of sound, 64 Quantitative analysis, 273 Quantity of urine, 43 i Quassin, 234 Quercitrin, 232 Quinidin, 243 Quinin, 243, 282, 332 Quinolin, 240 Radiation, 20 Radical, finding, 263 Radicals, 77 Radiometer, 33 Raoult's law, 23 Rasmussen's test for bile-pigments, 456 Reaction, 83 of degeneration, 51 of urine, 430 Reactions of water, 314 Reagent, 84 Red blood-cells in urine, 471 Reduction, 77, 92, 305 Refining of gold, 287, 292 Reflection, 34 Refraction, 34 Reinsch's test, 280 Rennin, 253, 381, 420 Resins, 198, 348 Resorcin, 235, 333 Respiration, 403 Respiratory diseases, 480 Retention of urine, 432 Rigor mortis, 369, 373 Roasting, 92 Roberts's test for albumin, 448 Roentgen rays, 55 Rosanilin, 234 Rosin, 198 Rosolic acid, 234 Ruberythric acid, 233 Ruhmkorff induction-coil, 54 Saccharin, 238, 322 Saccharose, 227 Saffranin, 233 Salicin, 232 Salicylates, 181 Salicylic acid, 217, 319, 333 Saliva, 381, 382 Salivary calculi, 382 Salol, 210, 333 Salophen, 210 Salt, 406 Salts, 82, 154 separation, 268 INDEX. 521 Sanitary analysis of water, 313 chemistry, 307 Santalin, 233 Santonin, 232, 356 Saponin, 232 Sarcin, 370 Sarcolactic acid, 369 Sarcolemma, 373 Sausage, 321, 349 Scale compounds, 102 Scammonin, 232 Sciagraphy, 55 Scillitin, 232 Scopolamin, 243 Sea-water, 311 Sebum, 386 Secondary current, 55 Secretions, 380, 403 Sediments in urine, 429, 459 Selenium, 123 Seminal fluid, 388 Sericin, 249 Serpentaria, 234 Sewer-gas poisoning, 353 Silicates, 173 Silicon, 128 Silver, 92 nitrate, 333 poisoning, 360 Simon's test, 281 Sinalbin, 232 Sinusoidal currents, 52 Skatol, 369 Skin affections, 482 Smegma, 386 Snake-bite, 363, 414 Soaps, 222, 333 Sodium, test, 282 Solanaceae, 242 Solanin, 232, 243 Solanum, 3.') 2 Solids, 8 Solubility of medicinal salts, acids, and bases, 295 of metals, 99 Solution, 28, 29 Sound, 63 Sources of heat, 19 of light, 33, 34 of metals, 90 Spartein, 242 Special incompatibility, 300 methods and apparatus, 279 Specific gravity, 5, 13, 15 of metals, 97 of urine, 432 heat, 24, 74 Specific infection, 478 Spectra, 39, 40 Spectroscope, 38, 380 Spermatozoa, 388, 444 Spermin, 388 Spheric aberration, 38 Spiegler's test for albumin, 448 Spigelin, 242 Spirit-level, 12 Spirits, 206, 324 Spongin, 249 Sputum, 394 Stabile compounds, 72 Standard solutions, 275 Stannates, 173 Starch, 226, 408 Starvation, 402 Static electricity, 43 Steapsin, 2o3, 381 Stearates, 180 Stearoptens, 197 Stercobilinuria, 456 Stereoscope, 36 Stoechiometry, 85 Stoneware, 74 Stools, 391 Storage battery, 47 Stramonium, 352 Strontium, test, 282 Strophanthin, 232 Strychnin, 244, 282, 356 Sublimation, 27, 92 Succinates, 180 Succinic acid, 216 Sucrose, 227 Sugar, adulterations, 322 in urine, 451 Sugars, detection, 289 Sulphates, 162, 337 in urine, 436 Sulphids, 161 Sulphites, 164 Sulphocarbolates, 181 Sulphocarbolic acid, 236 Sulphocarbonates, 168 Sulphocyanids, 182 Sulphonal, 237 Sulphur, 121 Sulphuric acid, 147 Sulphurous acid, 148, 333 Suppression of urine, 431 Suprarenal extracts, 390 Surgical conditions, 483 Symbols, 70 Sympathetic ink, 102 Synaptase, 251 Synovial fluid, 390 522 INDEX. Synthesis, 189 Syrup, 29 Systems of crystals, 58 Tannates, 179 Tannic acid, 333 Tannins, 217, 232 Tartar of teeth, 373 Tartaric acid, 216 Tartrates, 177 Taurin, 370 Taurocholic acid, 370 Tea, 323, 362, 410 Tears, 385 Teeth, 372 Telegraph, 57 Telephone, 56 Telescope, 35 Tellurium, 123 Temperature, 21 Tenacity, 9 of metals, 98 Tension, 48 Terpenes, 196 Test-metals, 418 Thallin, 240 Thebaicum group, 243 Thebain, 243 Thein, 245 Theobromin, 245, 370 Thermal unit, 31 Thermo-electricity, 52 Thermometers, 21 Thio-acids, 146 Thio-salts, 161 Thiosulphates, 165 Thymol, 334 Thyroidin, 390 Tin chlorid poisoning, 347 Toad-stool poisoning, 352 Tobacco, 324, 355, 360 Total solids of water, 314 Toxicology, 336 Toxins, 245, 412 Transparency of urine, 433 Transudates, 395 Trichloracetic acid, 215 Trional, 237 Triple phosphate crystals, 463 Trituration, chemic decomposition, 302 Trypsin, 252, 381 Tube-casts, 465 Tubercle bacilli, 414, 425, 476 Tungstates, 173 Tuning-fork, 65 Turpentine, 196, 334 Tyrosin, 239, 369, 462 Tyrotoxicon, 350 Ultimate analysis, 284 Ultramarine, 176 Urates, 460, 461, 464, 469 Urea, 238, 369, 391, 437 Urease, 254 Ureometer, 439 Uric acid, 370, 441, 460, 461 Urinary calculi, 483 casts, 465 crystals, 460 parasites, 474 sediments, 429 tumors, 474 Urine, 391, 425 Urinometer, 432 Urobilin, 426, 445 Urochrom, 426, 445 Uroerythrin, 446 Uroroseinogen, 446 Urotropin, 238, 334 Uses of metals, 104 Valence, 75 Valerianates, 177 Valeric acid, 215, 369 Vapor, 25 Vaselin, 194 Vegetable acids, 344 foods, 408 irritants, 348 Velocity, 7 of electricity, 52 of light, 34 of sound, 63 Veratrin, 244 Vernix caseosa, 386 Victor Meyer apparatus, 285 Vinegar, 322, 334 Viscera, 375 Visceral degeneration, 375 Viscosity, 10 Vital electricity, 52 Vitellin, 248 Volatile oils, 196 Volatilization tests, 272 Volt, 48 Volumetric methods, 275 Vomit, 393 Water, 131, 309, 366, 406 -gas, 194, 353 incompatibilities of, 302 of crystallization, 60 sanitary analysis, 313 INDEX. 523 Watt, 50 Weber, 49 Weight, 5 Wells, 310 Williamson's test for sugar, 453 Wines, 206, 323 Wood-silk, 226 -spirit, 205 Woorara, 356 Work, 7 Xanthin, 370 Xanthorhamnin, 233 X-rays, 55 Xylonite, 226 Yeast, 253, 420, 476 Yew, 349 Zein, 247 Zinc sulphate poisoning, 347 Zincates, 173 Zymase, 252 Zymogens, 380 UNIVERSITY OP CALIFORNIA MEDICAL SCHOOL LIBRARY THIS BOOK IS DUE ON THE LAST DATE STAMPED BELOW 1919 NGV 1 4 1923 1931 DEC 1931 QD31 Hill, E.G. H55 (PQ-gp-book of Chemistry. 1903 4751 JAM 18 1919 * I.WIWPRQITY Of PAIIFORNIA MEDICAL SCHOOL LIBRARY